JP7632777B1 - Suspension system and method for controlling suspension system - Google Patents

Abstract

[Problem] To realize a structure that allows smooth vehicle height adjustment. [Solution] When adjusting the vehicle height, if the direction of the rotational torque reversely input to the clutch output member 11 is the same as the direction in which the clutch input member 10 rotates, and the rotational speed of the clutch input member 10 is within a rotational speed range below a predetermined threshold where the jerking phenomenon is likely to occur, a controller 51 has a function of controlling the electric motor 3 so that the clutch input member 10 can quickly pass through that rotational speed range. [Selected Figure] Figure 1

Description

The present disclosure relates to a suspension device for supporting wheels on a vehicle body and a control method thereof.

In large vehicles such as buses, it is preferable to lower the vehicle height when the vehicle is stopped in order to make it easier for passengers to get on and off. In vehicles such as sports cars that are low in height and have a narrow gap between the bottom of the vehicle body and the road surface, it is preferable to raise the vehicle height in order to prevent the bottom of the vehicle body from contacting the step when going over a sidewalk step at very low speed, and to make it easier for passengers to get on and off. For this reason, the suspension systems of these vehicles may be equipped with a vehicle height adjustment device to raise or lower the vehicle height.

JP 2021-037868 A discloses a vehicle height adjustment device installed on a vehicle suspension system. This conventional vehicle height adjustment device includes a sleeve that is inserted into the shell of a shock absorber and has a male threaded portion, a housing that rotatably supports a top member that has a female threaded portion that screws into the male threaded portion, and a drive motor that rotates the top member. In the conventional vehicle height adjustment device, the drive motor rotates the top member to raise and lower the housing relative to the sleeve, and the spring bearing provided on the upper surface of the housing raises and lowers to adjust the vehicle height.

This vehicle height adjustment device further includes a reverse input cut-off clutch that is interposed between the drive motor and the frame member, transmits the forward and reverse rotation of the drive motor to the frame member, and prevents the reverse rotation input from the frame member from being transmitted to the drive motor. Therefore, with this vehicle height adjustment device, even if the drive motor is de-energized after the vehicle height is adjusted, the reverse input cut-off clutch prevents the frame member from rotating based on the weight of the vehicle body and occupants, and the vehicle height is maintained.

JP 2021-037868 A

The conventional vehicle height adjustment device described in JP 2021-037868 A may cause unstable behavior when adjusting the vehicle height.

In other words, before the vehicle height is adjusted, a force is applied from the wheel side to the output part of the reverse input cut-off clutch, tending to rotate the output part, based on the weight of the vehicle body and occupants, the elasticity of the spring, etc.

When the direction of the force applied to the output part of the clutch from the wheel side coincides with the direction in which the input part of the clutch is rotated by the drive motor to adjust the vehicle height to the desired height, if the rotation speed of the output part of the clutch is greater than the rotation speed of the input part of the clutch, the rotation of the case is locked and the rotation of the top member is also locked. However, even in this state, torque is being input to the input member, so the clutch is unlocked at the next moment and the top member rotates.

In other words, when the direction of the force applied to the output part of the clutch from the wheels based on the weight of the vehicle body and occupants, the elasticity of the spring, etc., coincides with the direction in which the input part of the clutch is rotated by the drive motor to adjust the vehicle height to the desired height, a jerking phenomenon may occur in which the input part and the output part intermittently rotate in a predetermined direction while the clutch alternates in a short period of time between an unlocked state in which torque can be transmitted between the input part and the output part, and a locked state in which torque cannot be transmitted between the input part and the output part. When the jerking phenomenon occurs, the behavior of the top member becomes unstable, making it impossible to adjust the vehicle height smoothly.

The present disclosure aims to realize a suspension system and a method for controlling the suspension system that enables smooth vehicle height adjustment.

The inventors of the present disclosure conducted extensive research into the conditions under which the jerking phenomenon occurs in a reverse input cut-off clutch that constitutes a suspension system, and discovered that the jerking phenomenon occurs when the rotation speed of the clutch input member rotating in a predetermined direction becomes smaller than a predetermined threshold value while torque in a predetermined direction is reversely input to the clutch output member. The suspension system of one embodiment of the present disclosure and the control method for the suspension system of one embodiment of the present disclosure have been completed based on this knowledge.

A suspension device according to one aspect of the present disclosure comprises a spring, a height adjustment mechanism, and a controller.

The spring is arranged to span between the vehicle body and the member that supports the wheel.

The vehicle height adjustment mechanism comprises an electric motor, a reverse input cut-off clutch, and a spring adjustment mechanism.

The electric motor has a motor output shaft.

The reverse input cut-off clutch has a clutch input member that is rotated based on the rotation of the motor output shaft, and a clutch output member. When rotational torque is input to the clutch input member, the rotational torque input to the clutch input member is transmitted to the clutch output member, whereas when rotational torque is input in reverse to the clutch output member, the rotational torque input in reverse to the clutch output member is not transmitted to the clutch input member.

The spring adjustment mechanism moves or rotates the spring vertically in response to rotation of the clutch output member.

The vehicle height adjustment mechanism adjusts the vehicle height, which is the height of the vehicle body from the wheel contact surface, by moving or rotating the spring vertically using the spring adjustment mechanism based on the rotational driving of the motor output shaft.

The controller controls the electric motor.

In particular, in the suspension system according to one aspect of the present disclosure, the controller
a first function of starting the motor output shaft at a first rotational acceleration when starting control to adjust the vehicle height in a direction in which the clutch input member is rotated in the same direction as the direction of the rotational torque reversely input to the clutch output member from a state in which the reverse input cut-off clutch is locked due to a rotational torque being reversely input to the clutch output member, and switching the rotational acceleration of the motor output shaft to a second rotational acceleration lower than the first rotational acceleration when the rotational speed of the clutch input member becomes greater than a predetermined first threshold value;
a second function of setting a target value of the rotational speed of the clutch input member to 0 when the direction of the rotational torque being reversely input to the clutch output member is the same as the rotational direction of the clutch input member, at a stage at which the control for adjusting the vehicle height is completed and the rotational speed of the clutch input member becomes equal to or lower than a predetermined second threshold value.

In one aspect of the suspension device of the present disclosure, the controller can have the first function and can be configured to control the output shaft of the motor by speed control or position control.

Alternatively, in a suspension device of one aspect of the present disclosure, the controller can have the first function and can be configured to control the motor output shaft by torque control when the rotational speed of the clutch input member is in a range from the start of the motor output shaft to the predetermined first threshold value or less, and to control the motor output shaft by speed control or position control after the rotational speed of the clutch input member becomes greater than the predetermined first threshold value.

In one aspect of the present disclosure, a suspension device includes:
The reverse input cutoff clutch is
A pressed member having a pressed surface on an inner circumferential surface thereof;
the clutch input member having an input side engaging portion arranged radially inside the pressed surface and arranged coaxially with the pressed surface;
the clutch output member having an output side engaging portion disposed radially inward of the input side engaging portion on the radial inner side of the pressed surface and disposed coaxially with the pressed surface;
an engaging element having a pressing surface opposing the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion, the engaging element being disposed so as to be movable in a radial direction;
It can be provided with:

When rotational torque is input to the clutch input member, the engaging element moves radially inward based on the engagement of the input side engaging portion with the input side engaged portion, and engages the output side engaged portion with the output side engaging portion, thereby transmitting the rotational torque input to the clutch input member to the clutch output member, whereas when rotational torque is input in reverse to the clutch output member, the output side engaging portion engages with the output side engaged portion, and the engaging element is configured to press the pressing surface against the pressed surface, frictionally engaging the pressing surface with the pressed surface.

In one aspect of the suspension device disclosed herein, the pressing surface can be constituted by two pressing surfaces.

In this case, the reverse input cutoff clutch is
When the two pressing surfaces are pressed against the pressed surface as the clutch output member rotates in a predetermined direction, and when the input side engaging portion and the input side engaged portion are engaged as the clutch input member rotates in a direction opposite to the predetermined direction, the distance between the contact portion between the input side engaging portion and the input side engaged portion and the center of rotation of the clutch input member in a second direction perpendicular to both a first direction which is the radial direction of the engager and the center of rotation of the clutch input member can be configured to be larger than the distance between the contact portion between the output side engaging portion and the output side engaged portion and the center of rotation of the clutch output member in the second direction,
When a rotational torque is input in reverse to the clutch output member and the two pressing surfaces are in contact with the pressed surface, the contact portion between the output side engaging portion and the output side engaged portion can be configured to be located closer to the center of rotation of the clutch output member in the first direction than a virtual straight line connecting the abutment portion between one of the two pressing surfaces and the pressed surface and the center of rotation of the clutch output member.

In one aspect of the suspension device disclosed herein, the reverse input cut-off clutch may include a biasing member that elastically biases the engaging element in a direction that brings the pressing surface closer to the pressed surface.

In one aspect of the suspension device of the present disclosure, the engaging element can be constituted by two engaging elements, and the input side engaging portion can be constituted by two input side engaging portions.

In one aspect of the suspension device of the present disclosure, the controller may have the first function, and the suspension device may have a speed sensor for measuring the rotation speed of the clutch input member, a stroke sensor for measuring the vehicle height, and/or an angle sensor for measuring the rotation angle of the clutch input member.

A suspension device according to one aspect of the present disclosure has a cylinder supported on the wheel and a piston supported on the vehicle body and fitted into the cylinder, and may be provided with a damper disposed in parallel with the spring between the vehicle body and the wheel.

The suspension device of one aspect of the present disclosure may include a spring seat that is supported to allow relative movement in the vertical direction with respect to the cylinder but not to allow relative rotation. In this case, the spring may be a coil spring that is elastically sandwiched between the vehicle body and the spring seat, and the spring adjustment mechanism may be configured to convert the rotational movement of the clutch output member into vertical movement of the spring seat with respect to the cylinder.

The spring adjustment mechanism may include a nut having an outer diameter side ball screw groove on its inner circumferential surface, which is rotationally driven based on the rotation of the clutch output member, and a plurality of balls arranged to be able to roll between the inner diameter side ball screw groove and the outer diameter side ball screw groove provided on the outer circumferential surface of the cylinder or the outer circumferential surface of a member supported and fixed to the cylinder. In this case, the nut may be supported so as to be able to move up and down and rotate relative to the cylinder, and to be able to move up and down integrally with the spring seat.

In the suspension device according to one aspect of the present disclosure, the spring may be a torsion bar. In this case, the spring adjustment mechanism may be configured to rotate the torsion bar in accordance with the rotation of the clutch output member.

A suspension system that is a target of the suspension system control method according to one aspect of the present disclosure includes:
A spring is provided so as to span between the vehicle body and a member supporting the wheel;
a reverse input cut-off clutch which has an electric motor having a motor output shaft, a clutch input member which is rotationally driven based on the rotation of the motor output shaft, and a clutch output member, and which transmits the rotational torque input to the clutch input member to the clutch output member when a rotational torque is input to the clutch input member, but does not transmit the rotational torque input inversely to the clutch output member to the clutch input member when a rotational torque is input inversely to the clutch output member; and a spring adjustment mechanism which moves or rotates the spring in a vertical direction in accordance with the rotation of the clutch output member, and which adjusts the height of the vehicle body from the ground surface of the wheels by moving or rotating the spring in a vertical direction using the spring adjustment mechanism based on the rotational driving of the motor output shaft;
Equipped with.

In one aspect of the present disclosure, a method for controlling a suspension system includes:
When control is started to adjust the vehicle height in a direction to rotate the clutch input member in the same direction as the direction of the rotational torque being reversely input to the clutch output member from a state in which the reverse input cut-off clutch is locked due to a rotational torque being reversely input to the clutch output member, the motor output shaft is started at a first rotational acceleration, and when the rotational speed of the clutch input member becomes greater than a predetermined first threshold value, the rotational acceleration of the motor output shaft is switched to a second rotational acceleration smaller than the first rotational acceleration.

In this case, the output shaft of the motor can be controlled by speed control or position control.

Alternatively, when the rotational speed of the clutch input member is in the range from the start of the motor output shaft to the predetermined first threshold value or less, the motor output shaft can be controlled by torque control, and after the rotational speed of the clutch input member becomes greater than the predetermined first threshold value, the motor output shaft can be controlled by speed control or position control.

Alternatively, in a control method for a suspension system according to an aspect of the present disclosure,
At the end stage of the control for adjusting the vehicle height, when the rotational speed of the clutch input member becomes equal to or lower than a predetermined second threshold value, if the direction of the rotational torque being reversely input to the clutch output member is the same as the rotational direction of the clutch input member, the target value of the rotational speed of the clutch input member is set to 0.

According to a suspension device of one embodiment of the present disclosure and a control method for a suspension device of one embodiment of the present disclosure, vehicle height adjustment can be performed smoothly.

FIG. 1 is a schematic cross-sectional view showing a suspension device according to a first embodiment of the present disclosure. 2(A) and 2(B) are schematic diagrams showing a suspension device of a first example, with FIG. 2(A) showing the device in a state where the vehicle height is raised, and FIG. 2(B) showing the device in a state where the vehicle height is lowered. FIG. 3 is a cross-sectional view showing the reverse input cutoff clutch taken out from the suspension system of the first example. FIG. 4 is a cross-sectional view taken along line XX of FIG. FIG. 5 is a view similar to FIG. 4, showing a state in which torque input to the clutch input member is transmitted to the clutch output member. FIG. 6 is a view similar to FIG. 4, but showing a state in which torque is reversely input to the clutch output member. 7A to 7C are schematic diagrams for explaining the effects of restricting the shapes of the input side engagement portion and the output side engagement portion. 8A to 8C are schematic diagrams for explaining the mechanism by which the jerking phenomenon occurs. FIG. 9 is a flow chart showing a control operation for adjusting the vehicle height by the suspension system of the first example. FIG. 10 is a diagram showing a schematic relationship between the rotation speed of the motor output shaft and time when adjusting the vehicle height. FIG. 11 is a diagram illustrating a suspension device according to a second example of the embodiment of the present disclosure. FIG. 12 is a flow chart showing a control operation for adjusting the vehicle height by the suspension system of the second example.

[First Example]
A first example of an embodiment of the present disclosure will be described with reference to FIGS. 1 to 10. FIG.

In the following description, the up-down direction, front-back direction, and width direction (left-right direction) refer to the up-down direction, front-back direction, and width direction (left-right direction) of the vehicle when the suspension device 1 is attached to the vehicle.

(Overall description of the suspension system)
The suspension device 1 is configured to press the outer circumferential surface (tread) of a tire constituting a wheel W against the road surface by the elasticity of the springs 2, while mitigating vibrations and shocks transmitted from the road surface to a vehicle body B via the wheel W. The suspension device 1 according to one aspect of the present disclosure has a function of adjusting the height (height of the lowest part) of the vehicle body B from the contact surface of the outer circumferential surface of the tire constituting the wheel W, i.e., the vehicle height (minimum ground clearance).

The suspension device 1 comprises a spring 2, a vehicle height adjustment mechanism 4, and a controller 51.

The spring 2 is arranged to span between the vehicle body B and the member supporting the wheel W, and generates elastic force to press the outer peripheral surface of the tire that constitutes the wheel W against the road surface, and has the function of absorbing the vibration or impact by elastically deforming when the wheel W is subjected to vibration or impact from the road surface.

The type of spring 2 is not particularly limited as long as it can perform its function. Specifically, spring 2 can be a coil spring that is made by winding a metal wire in a spiral shape and generates elasticity in the axial direction, or a torsion bar that is rod-shaped and generates elasticity in the torsional direction.

In this example, the spring 2 is a coil spring. The spring 2 is provided between the vehicle body B and a member supporting the wheel W, such as an axle, with its central axis facing approximately vertically. The spring 2 is elastically sandwiched between a top mount 20 supported and fixed to the vehicle body B and a spring seat 21 supported around the cylinder 13 of the damper 12. That is, the vehicle body side end 6, which is the upper end of the spring 2, is elastically abutted against the lower surface of the top mount 20 supported and fixed to the vehicle body B. In addition, the wheel side end 7, which is the lower end of the spring 2, is elastically abutted against the upper surface of the spring seat 21 supported by the wheel W via the cylinder 13, lower bracket 16, knuckle, etc.

In a vehicle equipped with the suspension device 1 of this example, the elastic restoring force of the spring 2 applies a downward elastic force to the spring seat 21, and this elastic force presses the outer peripheral surface of the tire that constitutes the wheel W against the road surface.

In addition, in a vehicle equipped with the suspension device 1 of this example, the up and down vibrations of the cylinder 13 due to vibrations from the wheels W, etc. are absorbed by the elastic deformation of the spring 2.

The vehicle height adjustment mechanism 4 comprises an electric motor 3, a reverse input cut-off clutch 5, and a spring adjustment mechanism 22.

The electric motor 3 has a motor output shaft 8.

The reverse input cutoff clutch 5 has a clutch input member 10 that is rotationally driven based on the rotation of the motor output shaft 8, and a clutch output member 11. When a rotational torque is input to the clutch input member 10, the reverse input cutoff clutch 5 transmits the rotational torque input to the clutch input member 10 to the clutch output member 11, whereas when a rotational torque is input in reverse to the clutch output member 11, the reverse input cutoff clutch 5 does not transmit the rotational torque input in reverse to the clutch output member 11 to the clutch input member 10.

The spring adjustment mechanism 22 moves or rotates the spring 2 in the vertical direction in response to the rotation of the clutch output member 11.

The vehicle height adjustment mechanism 4 adjusts the vehicle height by moving or rotating the spring 2 vertically using the spring adjustment mechanism 22 based on the rotational driving of the motor output shaft 8.

The spring adjustment mechanism 22 is configured to move or rotate the spring 2 in the vertical direction depending on the type, arrangement, etc. of the spring 2. Specifically, when the spring 2 is configured as a coil spring, the spring adjustment mechanism 22 is configured to move the spring 2 in the vertical direction. When the spring 2 is configured as a torsion bar, the spring adjustment mechanism 22 is configured to rotate the spring 2.

In this example, the spring 2 is a coil spring. The spring 2 is arranged around the damper 12, which is provided as an optional component. More specifically, the spring 2 and the damper 12 are arranged approximately coaxially.

The damper 12 is disposed in parallel with the spring 2 between the vehicle body B and the wheel W, and absorbs and reduces the vibration of the spring 2. The damper 12 includes a cylinder 13 supported on the wheel W, and a piston 14 supported on the vehicle body B and fitted in the cylinder 13.

The cylinder 13 has a cylindrical shape. The cylinder 13 has a cylinder space 15 therein. Oil is contained in the cylinder space 15. The lower end of the cylinder 13 is fixedly connected to a knuckle that supports the wheel W via a lower bracket 16.

The piston 14 has a head portion 17 and a rod portion 18.

The head portion 17 is fitted inside the cylinder space 15 so as to be capable of vertical displacement.

The rod portion 18 protrudes upward from the upper surface of the head portion 17 and passes through the upper plate portion 19 of the cylinder 13. The upper end of the rod portion 18 is connected and fixed to a top mount 20 that is supported and fixed to the vehicle body B.

When implementing a suspension device according to one embodiment of the present disclosure, the damper 12 may have either a single-tube or double-tube structure.

The suspension system 1 of this example includes a spring seat 21 that is supported so as to allow relative movement in the vertical direction but not allow relative rotation with respect to the cylinder 13. The spring seat 21 is disposed around the cylinder 13.

In this example, a protrusion 61 on the outer peripheral surface of the cylinder 13 is engaged with a groove 60 on the inner peripheral surface of the spring seat 21, thereby supporting the spring seat 21 so as to allow relative movement in the up and down direction relative to the cylinder 13 but prevent relative rotation. When implementing a suspension device according to one aspect of the present disclosure, the protrusion on the inner peripheral surface of the spring seat can also be engaged with a groove on the outer peripheral surface of the cylinder. In either case, the combination of the protrusion and the groove can be provided at only one location in the circumferential direction, or at multiple locations in the circumferential direction. The protrusion and the groove can also be omitted.

The spring adjustment mechanism 22 in this example is configured to move the spring 2 in the vertical direction by moving the spring seat 21 in the vertical direction. Specifically, the spring adjustment mechanism 22 is configured to convert the rotational motion of the clutch output member 11 into the vertical motion of the spring seat 21 relative to the cylinder 13.

The spring adjustment mechanism 22 can have any configuration as long as it can convert rotational motion into linear motion. For example, the spring adjustment mechanism 22 can be configured with a feed screw mechanism such as a sliding screw mechanism or a ball screw mechanism, or a cam mechanism that expands and contracts the axial dimension based on the rotation of a drive cam. In this example, the spring adjustment mechanism 22 is configured with a ball screw mechanism.

The spring adjustment mechanism 22 comprises a nut 23 and a plurality of balls 24.

The nut 23 has an outer diameter side ball screw groove 26 on its inner circumferential surface, and is driven to rotate based on the rotation of the clutch output member 11. The outer diameter side ball screw groove is formed in a spiral shape. In this example, the nut 23 is supported so as to be capable of vertical relative movement and relative rotation with respect to the cylinder 13, and to be capable of vertical movement integrally with the spring seat 21. More specifically, the nut 23 is supported around a portion of the cylinder 13 that is located below the spring seat 21, so as to be capable of vertical relative movement and relative rotation. The spring seat 21 is placed on the upper end face of the nut 23 via a bearing 27.

The bearing 27 has the function of supporting the thrust load between the spring seat 21 and the nut 23. As long as it has this function, its type is not particularly limited, and it can be composed of a rolling bearing such as a thrust needle bearing, a sliding bearing, etc.

A driven gear portion 28 is provided around the nut 23. The driven gear portion 28 is formed on the outer circumferential surface of the nut 23 directly or via a member separate from the nut 23.

The driven gear portion 28 meshes with a driving gear portion 30 provided around an intermediate shaft 29. The intermediate shaft 29 is connected to the motor output shaft 8 of the electric motor 3 via a reverse input cutoff clutch 5 so as to enable torque transmission.

Specifically, the motor output shaft 8 is connected and fixed to the clutch input member 10 of the reverse input cut-off clutch 5, or is configured integrally with the clutch input member 10. The intermediate shaft 29 is connected and fixed to the clutch output member 11 of the reverse input cut-off clutch 5, or is configured integrally with the clutch output member 11.

The balls 24 are arranged to be able to roll between an inner diameter side ball screw groove 25 provided on the outer peripheral surface of the cylinder 13 or the outer peripheral surface of a member supported and fixed to the cylinder 13, and an outer diameter side ball screw groove 26. In this example, the inner diameter side ball screw groove 25 is provided on the outer peripheral surface of the cylinder 13 in the vertical middle portion.

The start and end points of the load path are connected by a circulation path formed on the inner surface of the nut 23 or formed in a circulation part supported by the nut 23. The ball 24 that reaches the end point of the load path is returned to the start point of the load path through the circulation path. The start and end points of the load path are switched depending on the direction of movement of the nut 23 relative to the cylinder 13.

In this example, the rotation of the motor output shaft 8 is converted into vertical movement of the nut 23 by the spring adjustment mechanism 22, and the vertical position of the spring seat 21 can be adjusted by moving the spring seat 21 vertically together with the nut 23.

The controller 51 controls the electric motor 3.

To adjust the vehicle height in a vehicle equipped with the suspension system 1 of this example, electricity is applied to the electric motor 3 based on a command from the controller 51 to rotate the motor output shaft 8. The rotation of the motor output shaft 8 is transmitted to the intermediate shaft 29 via the reverse input cut-off clutch 5. The rotation of the intermediate shaft 29 is transmitted to the nut 23 via the meshing portion between the drive side gear portion 30 and the driven side gear portion 28. As the nut 23 rotates, multiple balls 24 circulate through the circulation path while rolling in the load path, causing the nut 23 to move vertically relative to the cylinder 13.

When the nut 23 moves up and down, the spring seat 21 mounted on the upper end face of the nut 23 via a bearing 27 also moves up and down. When the spring seat 21 moves up and down, the top mount 20 mounted on the upper surface of the spring seat 21 via a spring 2 also moves up and down together with the piston 14. As a result, the vehicle body B to which the top mount 20 is fixed moves up and down, and the vehicle height is adjusted.

After the vehicle height has been adjusted to the target value, power to the electric motor 3 is stopped.

When the outer circumferential surface of the tire that constitutes the wheel W is in contact with the road surface, a vertical force is applied to the spring seat 21 based on the weight of the vehicle body B and the occupant, the elasticity of the spring 2, etc. This force causes the nut 23 to move in the vertical direction, and a rotational torque is applied to the nut 23. The rotational torque applied to the nut 23 is transmitted to the intermediate shaft 29 via the meshing portion between the drive side gear portion 30 and the driven side gear portion 28.

The intermediate shaft 29 is connected and fixed to the clutch output member 11 or is configured integrally with the clutch output member 11, so that the rotational torque of the intermediate shaft 29 is supported by the reverse input cutoff clutch 5. This prevents the intermediate shaft 29 and the nut 23 from rotating, and also prevents the spring seat 21 and the nut 23 from moving up and down. As a result, the vehicle height is maintained constant even when the power supply to the electric motor 3 is stopped.

(Explanation of the structure of the reverse input cutoff clutch)
An example of the reverse input cutoff clutch 5 applicable to the suspension device 1 of this embodiment will be described in more detail below. However, when implementing the suspension device of one aspect of the present disclosure, the reverse input cutoff clutch 5 is not limited to the structure of this embodiment, and any structure can be adopted as long as it has the above-mentioned function. The reverse input cutoff clutch 5 of this embodiment includes a pressed member 31, a clutch input member 10, a clutch output member 11, and an engager 32.

The pressed member 31 has a pressed surface 33 on its inner circumferential surface. In this example, the pressed surface 33 is configured as a cylindrical surface whose inner diameter does not change in the axial direction.

The pressed member 31 is fixed to a fixed member such as a motor housing that accommodates the electric motor 3, or is integral with the fixed member so that its rotation is restricted.

The clutch input member 10 has an input side engagement portion 34 arranged radially inside the pressed surface 33 and is arranged coaxially with the pressed surface 33.

The input side engaging portion 34 is provided in a portion radially outward from the center of rotation O of the clutch input member 10, and is positioned so as to be able to engage with the input side engaged portion 45 of the engaging element 32. The input side engaging portion 34 is configured to engage with the input side engaged portion 45 as the clutch input member 10 or the engaging element 32 rotates.

In this example, the clutch input member 10 has, in addition to the input side engagement portion 34, a base portion 35 and an input shaft portion 36.

The substrate portion 35 has an approximately circular end face shape when viewed in the axial direction.

The input shaft portion 36 protrudes from the center of the side surface on one axial side (the right side in FIG. 3) of the base plate portion 35 toward one axial side. The input shaft portion 36 is fixedly coupled to the motor output shaft 8 or is integrally formed with the motor output shaft 8.

The number of input side engagement portions 34 is determined according to the number of engagement elements 32, and when the engagement elements 32 are composed of multiple engagement elements 32, the input side engagement portion 34 is also composed of multiple input side engagement portions 34.

In this example, the engaging element 32 is composed of two engaging elements 32. Therefore, the input side engaging portion 34 is composed of two input side engaging portions 34 to match the number of engaging elements 32.

The two input side engagement portions 34 are arranged at two radially opposite positions on the side surface on the other axial side (left side in Figure 3) of the base portion 35, and are spaced apart from each other in the radial direction of the clutch input member 10.

Each input side engaging portion 34 has a circumferentially symmetrical shape. In this example, each input side engaging portion 34 has an end face shape that is generally fan-shaped or generally trapezoidal, with the circumferential width increasing radially outward when viewed from the axial direction.

Specifically, the radial inner surfaces 37 of the two input side engagement portions 34 are formed of flat surfaces parallel to each other.

The radial outer surface 38 of the two input side engagement parts 34 is configured as a partial cylindrical surface. In this example, each radial outer surface 38 has a radius of curvature that is half the outer diameter of the base plate part 35. In other words, the outer peripheral surface of the base plate part 35 and the radial outer surface 38 of the two input side engagement parts 34 exist on the same imaginary cylindrical surface.

The two circumferential side surfaces 39 of each input side engagement portion 34 are configured as flat surfaces that incline away from each other as they extend radially outward.

The clutch output member 11 has an output side engagement portion 40 arranged radially inward of the pressed surface 33 relative to the input side engagement portion 34, and is arranged coaxially with the pressed surface 33. In other words, the clutch output member 11 is also arranged coaxially with the clutch input member 10.

The output side engaging portion 40 has a portion that is radially inward from the input side engaging portion 34 and radially outward from the rotation center O of the clutch output member 11, and is arranged in a position where the portion can engage with the output side engaged portion 46 of the engager 32. The output side engaging portion 40 is configured so that the portion engages with the output side engaged portion 46 as the clutch output member 11 or the engager 32 rotates.

In this example, the clutch output member 11 has an output shaft portion 41 in addition to the output side engagement portion 40. The output shaft portion 41 is fixedly connected to the intermediate shaft 29 or is integrally formed with the intermediate shaft 29.

The number of portions of the output side engaging portion 40 that engage with the output side engaged portions of the engaging elements 32 is determined according to the number of engaging elements 32, and when the engaging elements 32 are composed of multiple engaging elements 32, the output side engaging portion 40 is configured to have multiple engaging portions.

In this example, the output side engaging portion 40 is configured to have portions that engage with two output side engaged portions 46, corresponding to the number of engaging elements 32.

In this example, the output side engaging portion 40 has a generally rectangular or oval end face shape when viewed from the axial direction, and protrudes from the center of one axial end face of the output shaft portion 41 toward one axial side. In other words, the distance from the rotation center O of the clutch output member 11 to the outer circumferential surface of the output side engaging portion 40, which is the portion that engages with the output side engaged portion 46, is not constant in the circumferential direction. For this reason, the output side engaging portion 40 has a cam function.

More specifically, the outer peripheral surface of the output side engagement portion 40 is composed of two parallel flat surfaces 42 and two partially cylindrical convex surfaces 43. The two convex surfaces 43 are composed of partially cylindrical surfaces centered on the rotation center O of the clutch output member 11.

The output side engagement portion 40 is plane-symmetrical with respect to a first imaginary plane that includes the center of rotation O of the clutch output member 11 and is perpendicular to the flat surface 42, and is plane-symmetrical with respect to a second imaginary plane that includes the center of rotation O of the clutch output member 11 and is parallel to the flat surface 42.

The output side engagement portion 40 is positioned between the two input side engagement portions 34.

The engaging element 32 has a pressing surface 44 facing the pressed surface 33, an input side engaged portion 45 engageable with the input side engaging portion 34, and an output side engaged portion 46 engageable with the output side engaging portion 40, and is arranged so as to be capable of movement in a first direction, which is the direction toward or away from the pressed surface 33.

When a rotational torque is input to the clutch input member 10, the input side engaging portion 34 engages with the input side engaged portion 45, and the engaging element 32 moves in the first direction away from the pressed surface 33, engaging the output side engaged portion 46 with the output side engaging portion 40, thereby transmitting the rotational torque input to the clutch input member 10 to the clutch output member 11. When a rotational torque is input in reverse to the clutch output member 11, the output side engaging portion 40 engages with the output side engaged portion 46, and the pressing surface 44 is pressed against the pressed surface 33, causing frictional engagement of the pressing surface 44 with the pressed surface 33.

As long as the engaging element 32 has such a configuration, it can be composed of one engaging element 32 or two or more engaging elements 32.

In this example, the engaging element 32 is composed of two engaging elements 32. Each engaging element 32 functions as an engaging element 32. Each engaging element 32 has a substantially semicircular end face shape when viewed from the axial direction, and has a symmetrical shape with respect to the width direction (the direction shown by arrow B in FIG. 4). The configuration of each engaging element 32 will be described below.

In this example, the radial direction with respect to the engaging element 32 is the direction in which the pressing surface 44 approaches or approaches the pressed surface 33, and corresponds to the direction indicated by arrow A in Fig. 4. The width direction with respect to the engaging element 32 is the direction perpendicular to both the direction in which the pressing surface 44 approaches or approaches the pressed surface 33 and the axial direction of the clutch input member 10, and corresponds to the direction indicated by arrow B in Fig. 4. In this example, the radial direction with respect to the engaging element 32 corresponds to the first direction, and the width direction with respect to the engaging element 32 corresponds to the second direction.

The pressing surface 44 is provided on the radially outer surface of the engaging element 32 facing the pressed surface 33. In this example, the pressing surface 44 is composed of two pressing surfaces 44 provided at two positions on the radially outer surface of the engaging element 32 that are spaced apart from each other in the circumferential direction. Each pressing surface 44 is composed of a partially cylindrical convex curved surface having a radius of curvature smaller than the radius of curvature of the pressed surface 33.

When viewed from the axial direction, the portion of the radially outer surface of the engaging element 32 that is circumferentially offset from the two pressing surfaces 44 is located radially inward of an imaginary circle that is centered on the central axis O of the clutch input member 10 and is tangent to the two pressing surfaces 44. In other words, when the two pressing surfaces 44 are in contact with the pressed surface 33, the portion that is circumferentially offset from the two pressing surfaces 44 does not contact the pressed surface 33.

It is preferable that the pressing surface 44 has a surface property that has a larger coefficient of friction with the pressed surface 33 than the other parts of the engaging element 32. The pressing surface 44 can be formed integrally with the other parts of the engaging element 32, or can be formed by the surface of a friction material fixed to the other parts of the engaging element 32 by sticking, bonding, or the like.

In this example, the input side engaged portion 45 is provided at a radially intermediate portion of the widthwise center of the engaging element 32. More specifically, but not limited to, the input side engaged portion 45 has a generally arch-shaped opening shape when viewed from the axial direction, and is configured as a through hole that axially passes through a radially intermediate portion of the widthwise center of the engaging element 32.

The input side engaged portion 45 has a size that allows the input side engaging portion 34 to be loosely inserted. Therefore, with the input side engaging portion 34 inserted inside the input side engaged portion 45, there is a gap between the input side engaging portion 34 and the inner surface of the input side engaged portion 45 in the width direction and radial direction of the engaging element 32. Therefore, the input side engaging portion 34 can be displaced relative to the input side engaged portion 45 in the rotational direction of the clutch input member 10, and the input side engaged portion 45 can be displaced relative to the input side engaging portion 34 in the radial direction of the engaging element 32.

The shape of the input side engaged portion 45 is not limited as long as it is configured to be able to engage with the input side engaging portion 34. Although not limited thereto, in this example, the input side engaged portion 45 has a flat surface 47 on its radially outward surface that is parallel to the flat surface portion 49 provided on the radially inner surface of the engaging element 32, and a partially cylindrical concave curved surface 48 on its radially inward surface.

Alternatively, the input side engaged portion 45 can be configured as a bottomed hole that opens only to one axial side surface of the engaging element 32, or the input side engaged portion 45 can be configured as a notch that opens to the radially outer surface of the engaging element 32.

In this example, the output side engaged portion 46 is provided at the center of the width direction of the radially inner surface of the engaging element 32. The shape of the output side engaged portion 46 is not limited as long as it is configured to be able to engage with the output side engaging portion 40.

In this example, the engaging element 32 has a flat surface portion 49 on its radially inner surface, and two protrusions 50 protruding radially inward at two widthwise positions on the flat surface portion 49. The output-side engaged portion 46 is formed by a portion of the flat surface portion 49 that is between the two protrusions 50 in the width direction. Although not limited to this, the widthwise dimension of the output-side engaged portion 46, i.e., the distance between the two protrusions 50, is larger than the widthwise dimension of the flat surface 42 of the output-side engaging portion 40.

In the reverse input cutoff clutch 5 of this example, the pressing surfaces 44 of the two engaging elements 32 are oriented in opposite directions in the radial direction, and the flat surface portions 49 are opposed to each other, and each engaging element 32 is arranged radially inside the pressed member 31 so as to be movable in a first direction, which is the radial direction of each engaging element 32 and corresponds to the approach direction of the pressing surface 44 relative to the pressed surface 33. In addition, the two input side engaging portions 34 of the clutch input member 10 arranged on one axial side are axially inserted into the input side engaged portions 45 of the two engaging elements 32, and the output side engaging portion 40 of the clutch output member 11 arranged on the other axial side is axially inserted between the output side engaged portions 46 of the two engaging elements 32. In other words, the two engaging elements 32 are arranged so that the output side engaging portions 46 sandwich the output side engaging portions 40 from the radial outside.

When the two engaging elements 32 are positioned radially inside the pressed member 31, the inner diameter dimension of the pressed member 31 and the radial dimension of the engaging elements 32 are regulated so that there is a gap between the pressed surface 33 and the two pressing surfaces 44, and at least one of the portions between the tip faces of the convex portions 50 constituting each pair of two pairs of convex portions 50 formed by the two opposing convex portions 50 of the two engaging elements.

The reverse input cutoff clutch 5 of this example may further include a biasing member 52 (shown only in FIG. 4) that elastically biases the engaging element 32 in a direction that brings the pressing surface 44 closer to the pressed surface 33. The biasing member 52 elastically biases the engaging element 32 in a direction that brings the pressing surface 44 closer to the pressed surface 33 so that the pressing surface 44 of the engaging element 32 contacts the pressed surface 33 in a neutral state in which no torque is applied to either the clutch input member 10 or the clutch output member 11.

The biasing member 52 can be, but is not limited to, two biasing members 52 arranged at two positions in the width direction between the flat surface portions 49 of the two engaging elements 32. More specifically, each of the two biasing members 52 is made of a compression coil spring, and can be held in an elastically compressed state between the flat surface portions 49 of the two engaging elements 32. Each of the two biasing members 52 is arranged in a state in which it is prevented from falling off by inserting a convex portion 50 on the inside of both ends in the length direction between the convex portions 50 constituting each of the two pairs of the convex portions 50.

Alternatively, the urging member can be disposed between the flat surface portion 49 of the engaging element 32 and the clutch output member 11. In this case, the urging member can be configured by two urging members disposed between the flat surface portions 49 of the two engaging elements 32 and the clutch output member 11. Specifically, each of the two urging members can be configured by a leaf spring and can be engaged with the two engaging elements 32.

(Operation of the reverse input cutoff clutch)
The operation of the reverse input cutoff clutch 5 will be described with reference to Figures 5 and 6. Note that Figures 5 and 6 show radial gaps between the clutch input member 10 and the two engagers 32, and between the clutch output member 11 and the two engagers 32 in an exaggerated manner.

When a rotational torque is input to the clutch input member 10, the two engaging elements 32 move in a direction away from the pressed surface 33, regardless of the rotational direction of the clutch input member 10. More specifically, as shown in FIG. 5, the input side engaging portion 34 rotates inside the input side engaged portion 45 in the rotational direction of the clutch input member 10 (counterclockwise in the example of FIG. 5). This reduces the gap between the radial inner surface 37 of the input side engaging portion 34 and the flat surface 47 of the input side engaged portion 45, and brings the radial inner surface 37 of the input side engaging portion 34 into contact with the flat surface 47 of the input side engaged portion 45.

When the clutch input member 10 rotates further from this state, the flat surface 47 is pressed radially inward by the radial inner surface 37, and the engaging elements 32 move in a direction away from the pressed surface 33. In other words, the two engaging elements 32 move radially inward, that is, toward each other, based on their engagement with the clutch input member 10, so that the radial inner surfaces 37 of the two engaging elements 32 approach each other, and the output side engaging portion 40 of the clutch output member 11 is clamped from both radial sides by the output side engaged portions 46 of the two engaging elements 32.

In this way, while rotating the clutch output member 11 so that the flat surface 42 of the output side engaging portion 40 is parallel to the flat surface portion 49 of the engaging element 32, the output side engaging portion 40 and the output side engaged portion 46 of the engaging element 32 are engaged without rattle. As a result, the rotational torque input to the clutch input member 10 is transmitted to the clutch output member 11 via the two engaging elements 32 and is output from the clutch output member 11.

When a rotational torque is input in reverse to the clutch output member 11, the two engaging elements 32 move in a direction approaching the pressed surface 33, regardless of the rotational direction of the clutch output member 11. More specifically, as shown in FIG. 6, the output side engaging portion 40 rotates in the rotational direction of the clutch output member 11 (clockwise in the example of FIG. 6) inside the output side engaged portions 46 of the two engaging elements 32. The output side engaged portion 46 is pressed radially outward by the corner portion, which is the connection portion between the flat surface 42 and the convex curved surface 43, of the outer peripheral surface of the output side engaging portion 40, and the two engaging elements 32 move in a direction approaching the pressed surface 33.

That is, the two engaging elements 32 move radially outward, that is, in a direction away from each other, based on their engagement with the clutch output member 11, and the pressing surfaces 44 of the two engaging elements 32 come into contact with the pressed surface 33 and frictionally engage with the pressed surface 33. As a result, the rotational torque input in reverse to the clutch output member 11 is completely cut off and is no longer transmitted to the clutch input member 10.

In the reverse input cutoff clutch 5 of this example, the size of the gap between each component is adjusted so that the above operation is possible. In particular, in a positional relationship in which the pressing surfaces 44 of the two engaging elements 32 are in contact with the pressed surface 33, a gap is provided between the radial inner surface 37 of the input side engaging portion 34 and the flat surface 47 of the input side engaged portion 45 that allows the pressing surface 44 to be further pressed toward the pressed surface 33 based on the corner of the output side engaging portion 40 pressing against the output side engaged portion 46.

As a result, when a rotational torque is input in reverse to the clutch output member 11, the input side engagement portion 34 is prevented from blocking the radially outward movement of the engagement element 32, and even after the pressing surface 44 comes into contact with the pressed surface 33, the surface pressure acting on the contact portion between the pressing surface 44 and the pressed surface 33 changes according to the magnitude of the rotational torque input in reverse to the clutch output member 11, thereby ensuring that the clutch output member 11 is properly locked.

In the reverse input cutoff clutch 5 of this example, the rotation of the clutch input member 10 and the clutch output member 11 are both converted into radial movement of the engaging element 32. The reverse input cutoff clutch 5 is configured so that, as the engaging element 32 moves radially, the engaging element 32 engages with the clutch output member 11 located radially inside the engaging element 32, or the engaging element 32 is pressed against the pressed member 31 located radially outside the engaging element 32. That is, in the reverse input cutoff clutch 5 of this example, based on the radial movement of the engaging element 32 controlled by the rotation of each of the clutch input member 10 and the clutch output member 11, the clutch output member 11 is switched between an unlocked state in which rotation torque can be transmitted from the clutch input member 10 to the clutch output member 11, and a locked state in which rotation of the clutch output member 11 is prevented. This allows the axial dimension of the entire device of the reverse input cutoff clutch 5 to be shortened.

(Explanation of the dimensional relationship of each part of the reverse input cutoff clutch)
In the reverse input cutoff clutch 5 of this example, the dimensions and shapes of the components constituting the clutch input member 10, the clutch output member 11, and the two engagers 32 are regulated so as to satisfy the following relationships.

First, as the clutch output member 11 rotates in a predetermined direction (for example, the clockwise direction in Figure 4), the two pressing surfaces 44 of the engaging member 32 are pressed against the pressed surface 33, and as the clutch input member 10 rotates in a direction opposite to the predetermined direction (for example, the counterclockwise direction in Figure 4), the input side engaging portion 34 and the input side engaged portion 45 are engaged, i.e., a part of the input side engaging portion 34 is in contact with the input side engaged portion 45, in a state where a first distance D1 which is the distance in the second direction between a contact portion P _in between the input side engaging portion 34 and the input side engaged portion ₄₅ and the center of rotation _O of the clutch input member 10 is greater than a second distance D2 in the second direction between a contact portion P _out between the output side engaging portion 40 and the output side engaged portion 46 and the center of rotation O of the clutch output member 11 ( _D1 > _D2 ).

Also, as shown in FIG. 6 , in a locked state in which a rotational torque is input in reverse to the clutch output member 11 and the two pressing surfaces 44 of the engaging element 32 are in contact with the pressed surface 33, the contact portion _C1 between the output side engaging portion 40 and the output side engaged portion 46 is located closer to the center of rotation O of the clutch output member 11 in the first direction (the lower side in FIG. 6 ) than the virtual straight line L connecting the center of rotation O of the clutch output member ₁₁ and the abutment portion C2 between one of the two pressing surfaces 44, specifically, the pressing surface ₄₄ and the pressed surface 33 which is closer to the contact portion C1 than the center of rotation O of the clutch output member 11 in the second direction, and the center of rotation O of the clutch output member 11.

In the reverse input cutoff clutch 5 of this example, when torque in a predetermined direction (clockwise in Fig. 7(A) and Fig. 7(B)) is reversely input to the clutch output member 11, the clutch input member 10 can be rotated in the same direction as the predetermined direction to smoothly switch from a locked state to an unlocked state. The reason for this will be explained with reference to Figs. 7(A) and 7(B).

When torque is input to the clutch input member 10 in the locked state of the reverse input cutoff clutch 5, the two engagement elements 32 each tend to rotate about the contact portion _C1 .

When the contact portion _C1 is located farther from the rotation center O of the clutch output member 11 in the first direction than the virtual line L, as shown in Fig. 7B, when a clockwise rotational torque is input to the clutch input member 10, the engaging element 32 tends to rotate clockwise around the contact portion _C1 . When the contact portion _C1 is located farther from the rotation center O of the clutch output member 11 in the first direction than the virtual line L, the distance between the contact portion _C1 and the abutment portion _C2 is relatively large, so that of the two pressing surfaces 44, one pressing surface 44 located closer to the contact portion _C1 (the left side of Fig. 7B) tends to be strongly pressed against and bite into the pressed surface 33, as shown by the locus r in Fig. 7B by a dashed line.

Therefore, in a structure in which the contact portion _C1 is located farther from the rotation center O of the clutch output member 11 in the first direction than the virtual line L, when a torque in a predetermined direction is reversely input to the clutch output member 11, the clutch input member 10 must be rotated in the same direction as the predetermined direction to switch the reverse input cut-off clutch 5 from a locked state to an unlocked state, thereby releasing the biting of one of the pressing surfaces 44 into the pressed surface 33. As a result, the instantaneous maximum torque (peak torque) of the electric motor 3 for rotationally driving the clutch input member 10 becomes excessively large.

Like the reverse input cut-off clutch 5 of this example, even when the contact portion _C1 is located closer to the rotation center O of the clutch output member 11 in the first direction than the virtual line L, when a clockwise rotational torque is input to the clutch input member 10, the engager 32 tends to rotate clockwise around the contact portion _C1 as shown in Fig. 7(A). When the contact portion _C1 is located closer to the rotation center O of the clutch output member 11 in the first direction than the virtual line L, the distance between the contact portion _C1 and the abutment portion _C2 is relatively small, so that neither of the two pressing surfaces 44 is pressed against the pressed surface 33, as shown by the loci _r1 and _r2 in Fig. 7(A) by the dashed lines.

Therefore, in a structure in which the contact portion _C1 is located closer to the rotation center O of the clutch output member 11 in the first direction than the virtual line L, when a torque in a predetermined direction is reversely input to the clutch output member 11, the clutch input member 10 is rotated in the same direction as the predetermined direction, so that an instantaneous increase in the rotation torque of the clutch input member 10 can be suppressed even when the reverse input cutoff clutch 5 is switched from a locked state to an unlocked state. Therefore, in the reverse input cutoff clutch 5 of this example, compared to the structure shown in Fig. 7(B), when a torque in a predetermined direction is reversely input to the clutch output member 11, the clutch input member 10 can be rotated in the same direction as the predetermined direction to smoothly switch from a locked state to an unlocked state.

In addition, the reverse input cutoff clutch 5 of this example can smoothly switch from the unlocked state to the locked state. The reason for this will be explained with reference to Figure 7 (C).

Figure 7 (C) shows a state in which torque in a predetermined direction (clockwise in Figure 7 (C)) is input to the clutch output member 11, and a torque in the opposite direction to the predetermined direction (counterclockwise in Figure 7 (C)) is applied to the clutch input member 10.

When a counterclockwise torque is input to the clutch input member 10, the engaging member 32 tends to rotate counterclockwise around the contact portion _C1 . Then, as shown by the dashed line r in Fig. 7C, of the two pressing surfaces 44, the other pressing surface 44 located on the opposite side to the contact portion _C1 (the right side in Fig. 7C) across the rotation center O of the clutch output member 11 in the second direction tends to be pressed against the pressed surface 33.

Therefore, in the reverse input cutoff clutch 5 of this example, when a torque in a predetermined direction is reversely input to the clutch output member 11, a torque in a direction opposite to the predetermined direction is applied to the clutch input member 10, so that when switching from an unlocked state in which torque is transmitted from the clutch input member 10 to the clutch output member 11 to a locked state, the amount of movement of the engaging element 32 in the second direction required to press the pressing surface 44 against the pressed surface 33 is kept relatively small. Therefore, in the reverse input cutoff clutch 5 of this example, switching from the unlocked state to the locked state can be quickly performed.

However, when implementing the suspension device of one aspect of the present disclosure, it is also possible to use, as the reverse input cutoff clutch 5, a reverse input cutoff clutch in which the first distance _D1 is greater than the second distance _D2 and the contact portion _C1 is located on a side farther from the rotation center O of the clutch output member 11 in the first direction than the virtual straight line L. Alternatively, it is also possible to use, as the reverse input cutoff clutch 5, a reverse input cutoff clutch in which the first distance _D1 is smaller than the second distance _D2 .

(Explanation of the function to prevent the occurrence of jerking phenomenon in the reverse input cutoff clutch)
In the suspension system 1 of this example, in order to smoothly adjust the vehicle height, the controller 51 has a function of preventing the occurrence of a jerking phenomenon in the reverse input cut-off clutch 5. In other words, when adjusting the vehicle height, if the direction of the rotational torque reversely input to the clutch output member 11 is the same as the direction in which the clutch input member 10 is rotated, and the rotational speed of the clutch input member 10 is within a rotational speed range equal to or lower than a predetermined threshold value in which the jerking phenomenon is likely to occur, the controller 51 has a function of controlling the electric motor 3 so as to enable the electric motor 3 to quickly pass through that rotational speed range.

First, let us explain the mechanism by which the jerking phenomenon occurs.

In the suspension device 1, a force (rotational torque) that tends to rotate the clutch output member 11 is applied to the clutch output member 11 based on the weight of the vehicle body B and the occupant and the elasticity of the spring 2.

In a suspension system that adjusts vehicle height by vertically moving spring 2, which is made of a coil spring, like the suspension system 1 of this example, in normal conditions except when the vehicle is jacked up, a downward force is constantly applied to the spring seat 21 based on the weight of the vehicle body B and occupant, the elasticity of the spring, etc., and a rotational torque in a predetermined direction (for example, clockwise in Figures 8(A) to 8(C)) is constantly applied to the clutch output member 11 based on this force. Therefore, in the suspension system of this example, the direction of the rotational torque reversely input to the clutch output member 11 based on the weight of the vehicle body B and occupant coincides with the direction of the torque applied to the clutch input member 10 when lowering the vehicle height.

In the suspension device 1 of this example, when the vehicle height is lowered, the motor output shaft 8 is rotationally driven to rotate the clutch input member 10 in the predetermined direction, as shown in the order of Figures 8(A) to 8(B). At this time, if the rotation speed of the clutch output member 11 is greater than the rotation speed of the clutch input member 10, the output side engaged portion 46 is pressed radially outward by the output side engaging portion 40, and the pressing surface 44 frictionally engages with the pressed surface 33, and the rotation of the clutch input member 10 and the clutch output member 11 is locked, as shown in the order of Figures 8(B) to 8(C).

Even in this state, torque is input to the clutch input member 10 from the motor output shaft 8, so that at the next moment, as shown in Figure 8 (B), the reverse input cut-off clutch 5 switches from the locked state to the unlocked state.

In this way, when torque is input to the clutch output member 11 in the reverse direction and torque is input to the clutch input member 10 in the same direction as the torque being input to the clutch output member 11 in the reverse direction, a jerking phenomenon may occur in which the clutch input member 10 and the clutch output member 11 rotate intermittently while alternately repeating in a short period of time an unlocked state in which torque can be transmitted between the clutch input member 10 and the clutch output member 11 and a locked state in which torque cannot be transmitted between the clutch input member 10 and the clutch output member 11.

When starting control to adjust the vehicle height in a direction to rotate the clutch input member 10 in the same direction as the direction of the rotational torque (reverse input torque) that is reversely input to the clutch output member 11 from a state in which the reverse input cut-off clutch 5 is locked due to the rotational torque in the predetermined direction being reversely input to the clutch output member 11, the controller 51 executes a first function of starting the motor output shaft 8 at a first rotational acceleration _a1 , and switching the rotational acceleration of the motor output shaft 8 to a second rotational acceleration _a2 that is smaller than the first rotational acceleration _a1 at a _stage when the rotational speed Rin of the _clutch input member 10 becomes greater than a predetermined first threshold value T1, thereby making it possible to prevent the occurrence of a jerking phenomenon in an initial stage of the control.

The initial stage of control is a stage from immediately after the start of the electric motor 3 until the rotation speed _Rin of the clutch input member 10 reaches a predetermined first threshold value _T1 . The predetermined first threshold value _T1 is the rotation speed Rin of the clutch input member 10 that is sufficient to prevent the occurrence of the jerking phenomenon in the reverse input cut-off clutch ₅ , and is determined in advance by experiment or calculation.

The first rotational acceleration _a1 and the second rotational acceleration _a2 may each be a predetermined value that is set in advance, or may be determined each time depending on the current vehicle height, the target vehicle height, and the like.

It is preferable that the first rotational acceleration _a1 is set as large as possible within an adjustable range of the rotational acceleration of the motor output shaft 8, in order to quickly pass through the rotational speed range in which the jerking phenomenon is likely to occur.

The second rotational acceleration _a2 is set to an appropriate value according to the reduction ratio between the driving gear portion 30 and the driven gear portion 28, in order to prevent the occupant from feeling uncomfortable.

The controller 51 can be configured to control the motor output shaft 8 by speed control that controls the rotation speed of the motor output shaft 8 to a target value or by position control that controls the rotation position of the motor output shaft 8 to a target position, during the period from the start of the motor output shaft 8 to the end of control for adjusting the vehicle height to a target value. That is, the controller 51 controls the motor output shaft 8 by speed control or position control with the rotation acceleration set to a first rotation acceleration _a1 in a range in which R _in of the clutch input member 10 is equal to or smaller than a predetermined first threshold value _T1 from the start of the motor output shaft 8, and controls the motor output shaft 8 by speed control or position control with the rotation acceleration set to a second rotation acceleration _a2 after R _in of the clutch input member 10 becomes larger than the predetermined first threshold value _T1 .

Alternatively, the controller 51 can be configured to control the motor output shaft 8 by torque control, _which controls the rotational torque of the motor output shaft 8 to a target value, while the rotational speed Rin of the clutch input member 10 is in a range equal to or less than a predetermined first threshold value _T1 from the start of the motor output shaft 8, and to control the motor output shaft 8 by speed control or position control after the rotational speed Rin of the clutch input _member 10 becomes greater than the predetermined first threshold value _T1 .

In an electric motor 3 constituted by a servo motor capable of controlling torque, position, speed, etc., when the motor output shaft 8 is controlled by torque control, the motor output shaft 8 is generally rotationally driven at a higher rotational acceleration than when it is controlled by speed control or position control in order to quickly bring the motor output shaft 8 to a target value. Therefore, when the motor output shaft 8 is controlled by torque control, the rotational acceleration a1 in the range from the start of the motor output shaft 8 until the rotational speed R _in of the clutch input member 10 is equal to or lower than a predetermined first threshold value _T1 is greater than the rotational acceleration _a2 after the rotational speed R _in of the clutch input member 10 becomes greater than the predetermined first threshold value _T1 when the motor output shaft ₈ is controlled by speed control or position control.

Additionally or alternatively, the controller 51 has a second function of setting the target value of the rotational speed Rin of the clutch input member 10 _{to 0} when the direction of the rotational torque (reverse input torque) reversely input to the clutch output member 11 is the same as the rotational direction of the clutch input member 10 at the end stage of control to adjust the vehicle height when the rotational speed Rout of the clutch input member 10 becomes equal to or less than a predetermined _second threshold value T2.

The end stage of the control is the stage from when the vehicle height approaches the target value to when the rotation speed of the clutch input member 10 is reduced to 0, i.e., when the clutch input member 10 stops.

The state where the vehicle height is approaching the target value is, for example, a state where the remaining movement amount of the spring seat 21 to reach the target vehicle height is equal to or less than a predetermined amount. This predetermined amount is the amount by which the spring seat 21 moves while the clutch input member 10 is decelerating.

The predetermined second threshold _T2 is the rotation speed _Rin of the clutch input member 10 sufficient to prevent the occurrence of the jerking phenomenon in the reverse input cutoff clutch 5, and is determined in advance by experiment or calculation. The predetermined second threshold _T2 may be the same as the predetermined first threshold _T1 , or may be different from the predetermined first threshold _T1 .

In the suspension system 1 of this example, the controller 51 has both the first function and the second function. In this example, the predetermined first threshold value _T1 and the predetermined second threshold value _T2 are the same threshold value T.

Specifically, in the suspension system 1 of this example, which adjusts the vehicle height by vertically moving the spring 2 formed of a coil spring, when controlling to lower the vehicle height, from the start of the motor output shaft 8, while the rotation speed _Rin of the clutch input member 10 is within a range equal to or less than a predetermined threshold value T, the motor output shaft 8 is controlled by torque control, and after the rotation speed _Rin of the clutch input member 10 becomes greater than the predetermined threshold value T, the motor output shaft 8 is controlled by speed control or position control.

However, in the present example, in a suspension system 1 in which the vehicle height is adjusted by vertically moving the spring 2 formed of a coil spring, when controlling to lower the vehicle height, it is also possible to control the motor output shaft 8 by speed control or position control with the rotational acceleration set to a first rotational acceleration _a1 while the rotational speed Rin of the clutch input member 10 is in a range from the start of the motor output shaft ₈ to a predetermined threshold value T or less, and to switch the rotational acceleration to a second rotational acceleration _a2 which is smaller than the first rotational acceleration _a1 and control it by speed control or position control after the rotational speed _Rin of the clutch input member 10 becomes greater than the first predetermined threshold value _T1 .

Furthermore, at the end of the control for lowering the vehicle height, when the rotation speed _Rin of the clutch input member 10 becomes equal to or lower than the predetermined threshold value T, the target value of the rotation speed _Rin of the clutch input member 10 is set to zero.

The procedure for controlling the suspension system 1 in this example to lower the vehicle height will be explained with reference to the flowchart in Figure 9.

First, in S1, it is determined whether or not the control is to lower the vehicle height. This determination can be made based on the driver's operation of a switch, etc.

If it is determined in S1 that the vehicle height adjustment control is not a control to lower the vehicle height, but rather a control to raise the vehicle height, the process proceeds to S1-1, where the vehicle height is adjusted to the target value using speed control or position control, and then the process ends.

If in S1 it is determined that the vehicle height adjustment control is a control to lower the vehicle height, the process proceeds to S2 and the motor output shaft 8 and the clutch input member 10 are started by torque control.

For example, if the suspension device 1 has a stroke sensor, the target value for torque control can be determined by calculating the value of the torque being reverse-input to the clutch output member 11 based on the output value of the stroke sensor, and then determining the target value based on that value.

Alternatively, when the electric motor 3 is configured as a motor capable of detecting the rotational position of the motor output shaft 8, such as a stepping motor, the value of the torque being reversely input to the clutch output member 11 can be calculated based on the rotational position of the motor output shaft 8, and the target value can be obtained based on this value.

Alternatively, if the suspension device 1 has a torque sensor for measuring the rotational torque of the clutch output member 11, the target value for torque control can be determined based on the value of the torque being reversely input to the clutch output member 11 determined by the torque sensor.

In any case, the relationship between the value of the torque input inversely to the clutch output member 11 and the target value is determined in advance by experiment or calculation, and is stored in the memory of the controller 51 as a map, formula, or the like. Alternatively, the target value can be the product of the value of the torque input inversely to the clutch output member 11 and a predetermined value. The predetermined value is not limited to this, but can be, for example, 0.3 or more and 0.5 or less.

If the suspension system 1 does not include either a stroke sensor or a torque sensor, and the electric motor 3 is not configured as a motor capable of detecting the rotational position of the motor output shaft 8, the target value for torque control is first set to the minimum torque required according to the vehicle specifications. Then, the torque applied to the clutch input member 10 is gradually increased until the reverse input cut-off clutch 5 switches to the unlocked state. When the reverse input cut-off clutch 5 switches to the unlocked state, the value of the torque applied to the clutch input member 10 is held.

Whether the reverse input cutoff clutch 5 has switched to the unlocked state can be determined by the current value of the electric motor 3. That is, when the reverse input cutoff clutch 5 switches from the locked state to the unlocked state, the current value of the electric motor 3 decreases.

Next, in S3, it is determined whether the rotation speed _Rin of the clutch input member 10 is greater than a predetermined threshold value T. The rotation speed _Rin of the clutch input member 10 can be determined, for example, by a speed sensor provided around the clutch input member 10, the clutch output member 11, or the motor output shaft 8. Alternatively, the rotation speed _Rin can be determined based on the differential value of the output value of a stroke sensor for measuring the vehicle height, or the differential value of an angle sensor for measuring the rotation angle of the clutch input member 10, the clutch output member 11, or the motor output shaft 8.

If it is determined in S3 that the rotation speed _Rin of the clutch input member 10 is equal to or lower than the predetermined threshold value T ( _Rin ≦ T), torque control is continued to further increase the rotation speed _Rin of the clutch input member 10, and then the process returns to S3.

If it is determined in S3 that the rotation speed R _in of the clutch input member 10 is greater than a predetermined threshold value T (R _in >T), the process proceeds to S4, where the control mode of the motor output shaft 8 is switched from torque control to speed control or position control.

Next, in S5, it is determined whether the vehicle height is at the target value. This determination can be made based on the output signal of the stroke sensor, the rotational position of the motor output shaft 8, etc.

If in S5 it is determined that the vehicle height is not at the target value, control to lower the vehicle height continues, and after a predetermined time has elapsed, the process returns to S5.

If it is determined in S5 that the vehicle height is the target value, the process proceeds to S6, in which the rotation speed of the motor output shaft 8 is reduced while maintaining the control mode of the motor output shaft 8 at speed control or position control, thereby reducing the rotation speed _Rin of the clutch input member 10.

Next, in S7, it is determined whether the rotation speed _Rin of the clutch input member 10 is equal to or lower than a predetermined threshold value T.

If it is determined in S7 that the rotation speed _Rin of the clutch input member 10 is greater than the predetermined threshold value T, the rotation speed _Rin of the clutch input member 10 is further reduced, and after a predetermined time has elapsed, the process returns to S7.

When it is determined in S7 that the rotation speed _Rin of the clutch input member 10 is equal to or lower than the predetermined threshold value T, the process proceeds to S8, in which the target value of the rotation speed _Rin of the clutch input member 10 is set to 0. Specifically, the controller 51 issues an instruction to stop the electric motor 3.

In the suspension system 1 of this example, the first function causes the motor output shaft 8 to be rotationally driven by torque control in the initial stage of control to lower the vehicle height, so that the rotation speed _Rin of the clutch input member 10 can be quickly increased to a rotation speed range higher than a predetermined threshold value T in which jerking is unlikely to occur in the reverse input cutoff clutch 5, as shown by the range I in Fig. 10. Therefore, the occurrence of the jerking phenomenon in the initial stage of control to lower the vehicle height can be prevented, and smooth vehicle height adjustment can be performed.

In the initial stage of control for lowering the vehicle height, when the motor output shaft 8 is rotationally driven by speed control or position control, the increase in the rotation speed _Rin of the clutch input member 10 becomes slower than when the motor output shaft 8 is rotationally driven by torque control, as indicated by the two-dot chain line α in Fig. 10. For this reason, the time during which the rotation speed _Rin of the clutch input member 10 remains in the rotation speed range below the threshold value T where the jerking phenomenon is likely to occur becomes longer, making the jerking phenomenon more likely to occur.

Furthermore, according to the suspension device 1 of this example, the second function allows the rotation speed Rin of the clutch input member 10 to quickly pass through a rotation speed range below the threshold value _T where the jerking phenomenon is likely to occur in the reverse input cutoff clutch 5 and to reach 0 while the rotation speed _Rin of the clutch input member 10 is decreasing at the end stage of control to lower the vehicle height, as shown by the range E in Figure 10. This makes it possible to prevent the occurrence of the jerking phenomenon during the stage of lowering the vehicle height, and to perform smooth vehicle height adjustment.

At the end of the control for lowering the vehicle height, when the rotation speed _Rin of the clutch input member 10 becomes equal to or lower than the threshold value T, if the rotation speed _Rin of the clutch input member 10 is reduced without setting the target value of the rotation speed _Rin of the clutch input member 10 to 0, the reduction in the rotation speed _Rin of the clutch input member 10 becomes gradual, as shown by the two-dot chain line β in Fig. 10. Therefore, the time during which the rotation speed _Rin of the clutch input member 10 remains in the rotation speed range equal to or lower than the predetermined threshold value T where the jerking phenomenon is likely to occur becomes longer, and the jerking phenomenon becomes more likely to occur.

In particular, in the suspension system 1 of this embodiment, a reverse input cutoff clutch 5 is used that has a configuration that allows for rapid switching from an unlocked state to a locked state, and the jerking phenomenon is likely to occur when the rotational speed of the clutch input member 10 is in a range of rotational speeds below a predetermined threshold value T. For this reason, the effect of providing the first function and/or the second function is remarkable.

When the rotation speed of the motor output shaft 8 becomes zero and there is no torque input to the clutch input member 10, the reverse input cut-off clutch 5 switches to a locked state and the vehicle height is maintained.

When performing vehicle height adjustment control to raise the vehicle height in a vehicle equipped with the suspension system 1 of this example, the direction of the torque applied to the clutch input member 10 is opposite to the direction of the rotational torque input inversely to the clutch output member 11 based on the weight of the vehicle body B and the occupants, the elasticity of the spring 2, etc. Therefore, when performing vehicle height adjustment control to raise the vehicle height, the jerking phenomenon does not occur.

(Explanation of the function for suppressing the peak torque of the electric motor)
The controller 51 has a function for suppressing the peak torque of the electric motor 3 .

Specifically, when rotating the clutch input member 10 to adjust the vehicle height to the desired height from a state in which the reverse input cut-off clutch 5 is locked due to a rotational torque (reverse input torque) being reversely input to the clutch output member 11, if the direction in which the clutch input member 10 should be rotated is opposite to the direction of the torque (direction of the reverse input torque) that is reversely input to the clutch output member 11, the controller 51 has the function of rotating the clutch input member 10 in the direction of the reverse input torque for an extremely short, predetermined time, and then rotating the clutch input member 10 in the direction opposite to the direction of the reverse input torque.

The extremely short predetermined time is a time that allows the reverse input cutoff clutch 5 to be switched from a locked state to an unlocked state based on the rotational driving of the clutch input member 10 in the direction of the reverse input torque. Specifically, it is preferable that the extremely short predetermined time is as short as possible within a range in which the reverse input cutoff clutch 5 can be switched from a locked state to an unlocked state based on the rotational driving of the clutch input member 10 in the direction of the reverse input torque. More specifically, the extremely short predetermined time is not limited to this, but can be 0.001 seconds or more and 0.02 seconds or less, and preferably 0.001 seconds or more and 0.01 seconds or less.

In this example, the extremely short predetermined time is a time sufficient to separate the pressing surface 44 from the pressed surface 33 by rotating the clutch input member 10 in the direction of the reverse input torque.

In the reverse input cutoff clutch 5 of this example, in the locked state, the pressing surface 44 tends to be strongly pressed against and bite into the pressed surface 33. For this reason, when switching from the locked state to the unlocked state, it is necessary to release the pressing surface 44 from biting into the pressed surface 33.

In particular, when a rotational torque is input in reverse to the clutch output member 11, and the clutch input member 10 is rotated in a direction opposite to the direction of the torque input in reverse to the clutch output member 11 to switch from the locked state to the unlocked state, it is necessary to release the pressing surface 44 from the pressed surface 33 while resisting the force applied to the engaging member 32 based on the rotational torque input in reverse to the clutch output member 11 to move the pressing surface 44 closer to the pressed surface 33. Therefore, the magnitude of the output torque required of the electric motor 3 is greatest when a rotational torque is input in reverse to the clutch output member 11, and the clutch input member 10 is rotated in a direction opposite to the direction of the torque input in reverse to the clutch output member 11 to switch from the locked state to the unlocked state.

Specifically, but not limited to, in the state after the reverse input cutoff clutch 5 of this example has been switched to the unlocked state, the torque τ _R required to rotate the clutch input member 10 in the direction opposite to the direction of the torque reversely input to the clutch output member 11 is 20% or more and 80% or less of the torque τ _UN required to switch the reverse input cutoff clutch 5 to the unlocked state by rotating the clutch input member 10 in the direction opposite to the direction of the torque reversely input to the clutch output member 11.

In this example of the suspension system 1, which adjusts the vehicle height by vertically moving the spring 2, which is made of a coil spring, when controlling to raise the vehicle height, the direction in which the clutch input member 10 should be rotated is opposite to the direction of the torque being input inversely to the clutch output member 11.

Therefore, in the suspension system 1 of this example, when raising the vehicle height, the controller 51 rotates and drives the clutch input member 10 in the same direction as the direction of the torque reversely input to the clutch output member 11 based on the weight of the vehicle body and occupants to move the pressing surface 44 away from the pressed surface 33, and then reverses the rotational direction of the clutch input member 10. Therefore, even when current is applied to the electric motor 3 to switch the reverse input cut-off clutch 5 from a locked state to an unlocked state in order to raise the vehicle height, it is possible to prevent the output torque required of the electric motor 3 from becoming excessive, and the electric motor 3 can be made smaller.

In addition, while control is being executed to suppress the peak torque of the electric motor 3, the motor output shaft 8 can be controlled by speed control or position control, or by torque control.

[Second Example]
A second example of the embodiment of the present disclosure will be described with reference to FIGS. 11 and 12. FIG.

In the suspension device 1a of this example, the spring 2a is a rod-shaped torsion bar that generates elasticity in the torsional direction. The vehicle height adjustment mechanism 4a also includes a spring adjustment mechanism 22a that rotates the spring 2a in response to the rotation of the clutch output member 11.

The spring 2a is supported by the vehicle body B so that its central axis is approximately parallel to the bottom surface of the vehicle body B and so that it can rotate around the central axis. More specifically, the spring 2a is supported by the lower part of the vehicle body B so that its central axis is oriented approximately in the width direction and so that it can rotate around the central axis.

The spring adjustment mechanism 22a is constructed by connecting and fixing the clutch output member 11 to the spring 2a directly or via a reducer 53.

In this example, the spring adjustment mechanism 22a is configured by connecting and fixing the clutch output member 11 to the spring 2a via a reduction gear 53. Specifically, the output shaft 56 of the reduction gear 53 is connected and fixed to the vehicle body side end 6a, which is the end on the inner side in the width direction of the spring 2a (the right side in FIG. 11), and the input shaft 57 of the reduction gear 53 is connected and fixed to the clutch output member 11 of the reverse input cutoff clutch 5, or is configured integrally with the clutch output member 11. In addition, the motor output shaft 8a of the electric motor 3a is connected and fixed to the clutch input member 10 of the reverse input cutoff clutch 5, or is configured integrally with the clutch input member 10.

The type of the reducer 53 is not particularly limited. For example, the reducer 53 can be configured as a parallel shaft gear reducer, a worm reducer, a planetary gear reducer, a belt reducer, or the like.

The vehicle height adjustment mechanism 4a further includes a lever 54 that is fixedly connected to the spring 2a and configured to move the knuckle 55 supporting the wheel W in the vertical direction as the spring 2a rotates.

The base end of the lever 54 (the end on the right side in FIG. 11) is fixed to the wheel side end 7a, which is the end on the outer side in the width direction (the left side in FIG. 11) of the spring 2a. The tip end of the lever 54 (the end on the left side in FIG. 11) is supported by the knuckle 55 so as to be able to swing about a pivot point that faces approximately in the width direction.

The tip of the lever 54 is positioned at a position offset from the base end in the front-rear direction. Therefore, when the tip of the lever 54 is swung around the base end of the lever 54 by rotating the spring 2a, the knuckle 55 moves up and down. In this example, the base end portion of the lever 54 extends approximately in the front-rear direction, and the tip end portion extends outward in the width direction as it moves toward the front.

The knuckle 55 is supported by two arms 58a, 58b to be movable up and down with respect to the vehicle body B. The upper arm 58a supports its base end on the vehicle body B to be able to swing about a pivot axis facing approximately in the fore-aft direction, and its tip end on the upper part of the knuckle 55 to be able to swing about a pivot axis facing approximately in the fore-aft direction. The lower arm 58b supports its base end on the vehicle body B via the damper 12a to be able to swing about a pivot axis facing approximately in the fore-aft direction, and its tip end on the lower part of the knuckle 55 to be able to swing about a pivot axis facing approximately in the fore-aft direction.

When implementing the suspension device of one embodiment of the present disclosure and the control method for the suspension device of one embodiment of the present disclosure, the spring formed by the torsion bar can be supported on the vehicle body with its central axis oriented in the approximately fore-aft direction and capable of rotation about the central axis. In this case, the arm supporting the knuckle can be swung about its base end as the spring rotates, thereby making it possible to adjust the vehicle height.

In addition to the spring 2a, the suspension device 1a can also include a spring 59 arranged in parallel with the damper 12a between the base end of the lower arm 58b and the vehicle body B. The suspension device 1a in this example includes a spring 59 made of a coil spring.

In order to adjust the vehicle height in a vehicle equipped with the suspension system 1a of this example, electricity is applied to the electric motor 3 to rotate the motor output shaft 8, which rotates the spring 2a via the reduction gear 53. This causes the tip of the lever 54 to swing around the base end of the lever 54, moving the knuckle 55 up and down, thereby moving the wheel W supported by the knuckle 55 up and down relative to the vehicle body B.

In the suspension device 1a of this example, due to an imbalance between the weight of the vehicle body B and the occupant and the elastic force of the spring 2, a force (rotational torque) that tends to rotate the clutch output member 11 is applied to the clutch output member 11.

Specifically, when the vehicle height is higher than the neutral position where the weight of the vehicle body B and the occupant is balanced with the elastic force of the spring 2, the direction of the rotational torque reversely input from the wheel W side to the clutch output member 11 is the same as the direction in which the clutch input member 10 should be rotated to lower the vehicle height. On the other hand, when the vehicle height is lower than the neutral position, the direction of the rotational torque applied to the clutch output member 11 from the wheel W side is the same as the direction in which the clutch input member 10 should be rotated to raise the vehicle height.
(Explanation of the function to prevent the occurrence of jerking phenomenon in the reverse input cutoff clutch)

In the present example of the suspension device 1a, the controller 51 also has a first function and a second function of preventing jerking from occurring in the reverse input cut-off clutch 5.

Specifically, in the suspension device 1a of this example, when the vehicle height is adjusted in a direction that rotates the clutch input member 10 in the same direction as the direction of the rotational torque being reversely input to the clutch output member 11, from the start of the motor output shaft 8, in a range in which _Rin of the clutch input member 10 is equal to or less than a predetermined first threshold value _T1 , the motor output shaft 8 is controlled by speed control or position control with the rotational acceleration set to a first rotational acceleration _a1 , and after _Rin of the clutch input member 10 becomes greater than the predetermined first threshold value _T1 , the rotational acceleration is controlled by speed control or position control _with the _second rotational acceleration a2 smaller than the first rotational acceleration a1.

However, in the present example, in a suspension device 1a in which the vehicle height is adjusted by rotating a spring 2a formed of a torsion bar, when the vehicle height is adjusted in a direction that rotates the clutch input member 10 in the same direction as the direction of the rotational torque that is reversely input to the clutch output member 11, the motor output shaft 8 can be controlled by torque control in a range from the start of the motor output shaft 8 where the rotational speed _Rin of the clutch input member 10 is less than a predetermined threshold value T, and the motor output shaft 8 can also be controlled by speed control _or position control from the stage where the rotational speed Rin of the clutch input member 10 becomes equal to or greater than the predetermined threshold value T until the end of the control for adjusting the vehicle height to a target value.

In addition, at the end stage of the control for adjusting the vehicle height, when the rotation speed _Rin of the clutch input member 10 becomes equal to or lower than the predetermined threshold value T, if the direction of the reverse input torque and the rotation direction of the clutch input member 10 are the same, the target value of the rotation speed _Rin of the clutch input member 10 is set to 0.

The procedure for performing control to adjust the vehicle height using the suspension device 1a in this example will be explained with reference to the flowchart in Figure 12.

First, in S1, in order to adjust the vehicle height to the desired height, it is determined whether the direction in which the clutch input member 10 should be rotated is the same as the direction of the rotational torque (reverse input torque) that is being reversely input to the clutch output member 11 due to an imbalance between the weight of the vehicle body B or occupant and the spring 2.

This determination can be made based on the vehicle height at that time obtained based on the output signal of the stroke sensor, the weight of the occupants and cargo obtained by a weight sensor, the operation of a switch by the driver, etc.

If it is determined in S1 that the direction in which the clutch input member 10 should be rotated is different from the direction of the reverse input torque, the process proceeds to S1-1, the motor output shaft 8 is started at the second rotational acceleration _a2 , and adjustment of the vehicle height is started by speed control or position control, and then the process proceeds to S7.

If it is determined in S1 that the direction in which the clutch input member 10 should be rotationally driven is the same as the direction of the reverse input torque, the process proceeds to S2, in which the motor output shaft 8 is started at a first rotational acceleration _a1 .

Next, in S3, it is determined whether the rotation speed _Rin of the clutch input member 10 is greater than a predetermined threshold value T.

If it is determined in S3 that the rotation speed _Rin of the clutch input member 10 is equal to or lower than a predetermined threshold value T ( _Rin ≦ T), the rotation speed _Rin of the clutch input member 10 is further increased while maintaining the rotational acceleration of the motor output shaft 8 at _a1 , and then the process returns to S3.

If it is determined in S3 that the rotation speed _Rin of the clutch input member 10 is greater than a predetermined threshold value T ( _Rin >T), the process proceeds to S4, in which the rotation acceleration of the motor output shaft 8 is switched to _a2 which is smaller than _a1 .

Next, in S5, it is determined whether the vehicle height is at the target value. This determination can be made based on the output signal of the stroke sensor, the rotational position of the motor output shaft 8, etc.

If in S5 it is determined that the vehicle height is not at the target value, control to adjust the vehicle height continues, and after a predetermined time has elapsed, the process returns to S5.

If it is determined in S5 that the vehicle height is equal to the target value, the process proceeds to S6, in which the rotation speed of the motor output shaft 8 is reduced, and the rotation speed _Rin of the clutch input member 10 is reduced.

Next, in S7, it is determined whether the rotation speed _Rin of the clutch input member 10 is equal to or lower than a predetermined threshold value T.

If it is determined in S7 that the rotation speed _Rin of the clutch input member 10 is greater than the predetermined threshold value T, the rotation speed _Rin of the clutch input member 10 is further reduced, and after a predetermined time has elapsed, the process returns to S7.

If it is determined in S7 that the rotation speed _Rin of the clutch input member 10 is equal to or lower than the predetermined threshold value T, the process proceeds to S8, where it is determined whether the rotation direction of the clutch input member 10 is the same as the direction of the rotational torque (reverse input torque) that is reversely input to the clutch output member 11 due to an imbalance between the weight of the vehicle body B or occupant and the elastic force of the spring 2. The direction of the reverse input torque can be obtained based on the vehicle height at that time, which is obtained based on the output signal of the stroke sensor, etc., and the weight of the occupant, cargo, etc., obtained by a weight sensor, etc.

If it is determined in S8 that the rotation direction of the clutch input member 10 is different from the direction of the reverse input torque, the rotation speed _Rin of the clutch input member 10 is reduced at the same deceleration rate, and the rotation speed _Rin of the clutch input member 10 is set to 0, and then the process ends.

If it is determined in S8 that the rotation direction of the clutch input member 10 is the direction of the reverse input torque, the process proceeds to S9, where the target value of the rotation speed _Rin of the clutch input member 10 is set to 0. Specifically, the controller 51 issues an instruction to stop the electric motor 3.

In the suspension device 1a of this embodiment as well, the first function activates the motor output shaft 8 at the first rotational acceleration _a1 in the initial stage of control for adjusting the vehicle height in a direction that rotates the clutch input member 10 in the same direction as the direction of the rotational torque being reversely input to the clutch output member 11. This makes it possible to quickly increase the rotation speed _Rin of the clutch input member 10 to a rotation speed range that is higher than a predetermined threshold value T in which the jerking phenomenon is unlikely to occur in the reverse input cut-off clutch 5. This makes it possible to prevent the occurrence of the jerking phenomenon in the initial stage of control for adjusting the vehicle height, and to perform smooth vehicle height adjustment.

Furthermore, according to the suspension device 1a of this example, the second function allows the rotational speed Rin of the clutch input member 10 to quickly pass through a rotational speed range below the threshold T where jerking is likely to occur in the reverse input cut-off clutch 5 and become 0 when the control for adjusting the vehicle height is at its final stage and the direction of the rotational torque _reversely input to the clutch output member 11 is the same as the rotational direction of the clutch input member 10. This makes it possible to prevent the occurrence of the jerking phenomenon in the stage of lowering the vehicle height, and to perform smooth vehicle height adjustment.

(Explanation of the function for suppressing the peak torque of the electric motor)
Also in the suspension device 1 a of this embodiment, the controller 51 has a function for suppressing the peak torque of the electric motor 3 .

In this example, when the clutch input member 10 is rotated to adjust the vehicle height to the desired height from a state in which the reverse input cut-off clutch 5 is locked due to a rotational torque (reverse input torque) being reverse input to the clutch output member 11, if the direction in which the clutch input member 10 should be rotated is opposite to the direction of the torque (direction of the reverse input torque) reversely input to the clutch output member 11, the controller 51 has the function of rotating the clutch input member 10 in the direction of the reverse input torque for a very short predetermined time, in this example, a time sufficient to separate the pressing surface 44 from the pressed surface 33, and then rotating the clutch input member 10 in the direction opposite to the direction of the reverse input torque.

More specifically, when the vehicle height is higher than the neutral position and control is performed to raise the vehicle height, the controller 51 rotates the clutch input member 10 for an extremely short time in the direction in which the vehicle height is lowered, and then rotates the clutch input member 10 in the direction in which the vehicle height is raised, thereby adjusting the vehicle height to the desired height. Also, when the vehicle height is lower than the neutral position and control is performed to lower the vehicle height, the controller 51 rotates the clutch input member 10 for an extremely short time in the direction in which the vehicle height is raised, and then rotates the clutch input member 10 in the direction in which the vehicle height is lowered, thereby adjusting the vehicle height to the desired height.

In the suspension device 1a of this example, when current is applied to the electric motor 3 to switch the reverse input cut-off clutch 5 from a locked state to an unlocked state, the output torque required of the electric motor 3 can be prevented from becoming excessive, and the electric motor 3 can be made smaller.

The configuration and effects of other parts of the second example are the same as those of the first example.

LIST OF SYMBOLS 1, 1a Suspension device 2, 2a Spring 3, 3a Electric motor 4, 4a Height adjustment mechanism 5 Reverse input cutoff clutch 6, 6a Vehicle body side end 7, 7a Wheel side end 8, 8a Motor output shaft 10 Clutch input member 11 Clutch output member 12, 12a Damper 13 Cylinder 14 Piston 15 Cylinder space 16 Lower bracket 17 Head portion 18 Rod portion 19 Upper plate portion 20 Top mount 21 Spring seat 22, 22a Spring adjustment mechanism 23 Nut 24 Ball 25 Inner diameter side ball screw groove 26 Outer diameter side ball screw groove 27 Bearing 28 Driven side gear portion 29 Intermediate shaft 30 Driving side gear portion 31 Pressed member 32 Engagement piece 33 Pressed surface 34 Input side engagement portion Reference Signs List 35 Base plate portion 36 Input shaft portion 37 Radial inner surface 38 Radial outer surface 39 Circumferential side surface 40 Output side engaging portion 41 Output shaft portion 42 Flat surface 43 Convex surface 44 Pressing surface 45 Input side engaged portion 46 Output side engaged portion 47 Flat surface 48 Concave surface 49 Flat surface portion 50 Convex portion 51 Controller 52 Urging member 53 Speed reducer 54 Lever 55 Knuckle 56 Output shaft 57 Input shaft 58a, 58b Arm 59 Spring 60 Concave groove 61 Convex portion

Claims (15)

A spring is provided so as to span between the vehicle body and a member supporting the wheel;
a reverse input cut-off clutch that has an electric motor having a motor output shaft, a clutch input member that is rotationally driven based on the rotation of the motor output shaft, and a clutch output member, and that transmits the rotational torque input to the clutch input member to the clutch output member when a rotational torque is input to the clutch input member, but does not transmit the rotational torque reversely input to the clutch output member to the clutch input member when a rotational torque is reversely input to the clutch output member; and a spring adjustment mechanism that moves or rotates the spring in a vertical direction in accordance with the rotation of the clutch output member, and adjusts the vehicle height, which is the height of the vehicle body from the ground contact surface of the wheel, by moving or rotating the spring in a vertical direction by the spring adjustment mechanism based on the rotational driving of the motor output shaft;
A controller for controlling the electric motor;
Equipped with
The controller includes:
a first function of starting the motor output shaft at a first rotational acceleration when starting control to adjust the vehicle height in a direction to rotate the clutch input member in the same direction as the direction of the rotational torque reversely input to the clutch output member from a state in which the reverse input cut-off clutch is locked due to a rotational torque being reversely input to the clutch output member, and switching the rotational acceleration of the motor output shaft to a second rotational acceleration lower than the first rotational acceleration when the rotational speed of the clutch input member becomes greater than a predetermined first threshold value;
a second function of setting a target value of the rotational speed of the clutch input member to 0 when the direction of the rotational torque reversely input to the clutch output member is the same as the rotational direction of the clutch input member at a stage where the control for adjusting the vehicle height is completed and the rotational speed of the clutch input member becomes equal to or less than a predetermined second threshold value;
Suspension system. The suspension system of claim 1, wherein the controller has the first function and is configured to control the motor output shaft by speed control or position control. The suspension device according to claim 1, wherein the controller has the first function, and is configured to control the motor output shaft by torque control when the rotation speed of the clutch input member is within the range from the start of the motor output shaft to the predetermined first threshold, and to control the motor output shaft by speed control or position control after the rotation speed of the clutch input member becomes greater than the predetermined first threshold. The reverse input cutoff clutch is
A pressed member having a pressed surface on an inner circumferential surface thereof;
the clutch input member having an input side engaging portion arranged radially inside the pressed surface and arranged coaxially with the pressed surface;
the clutch output member having an output side engaging portion disposed radially inward of the input side engaging portion on the radial inner side of the pressed surface and disposed coaxially with the pressed surface;
an engaging element having a pressing surface opposing the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion, the engaging element being disposed so as to be movable in a radial direction;
Equipped with
When a rotational torque is input to the clutch input member, the engaging element moves radially inward based on the engagement of the input side engaging portion with the input side engaged portion, and transmits the rotational torque input to the clutch input member to the clutch output member by engaging the output side engaged portion with the output side engaging portion, whereas when a rotational torque is input in reverse to the clutch output member, the output side engaging portion engages with the output side engaged portion, and the engaging element presses the pressing surface against the pressed surface, frictionally engaging the pressing surface with the pressed surface.
A suspension system according to any one of claims 1 to 3. The pressing surface is composed of two pressing surfaces,
The reverse input cutoff clutch is
When the two pressing surfaces are pressed against the pressed surface as the clutch output member rotates in a predetermined direction, and when the input side engaging portion and the input side engaged portion are engaged as the clutch input member rotates in a direction opposite to the predetermined direction, a distance between a contact portion between the input side engaging portion and the input side engaged portion and the center of rotation of the clutch input member in a second direction perpendicular to both a first direction which is a radial direction of the engager and the center of rotation of the clutch input member is greater than a distance between a contact portion between the output side engaging portion and the output side engaged portion and the center of rotation of the clutch output member in the second direction,
a contact portion between the output side engaging portion and the output side engaged portion is configured to be located closer to the center of rotation of the clutch output member in the first direction than a virtual straight line connecting a contact portion between one of the two pressing surfaces and the pressed surface and the center of rotation of the clutch output member when a rotational torque is input in reverse to the clutch output member and the two pressing surfaces are in contact with the pressed surface;
5. The suspension system of claim 4. 5. The suspension system according to claim 4 , wherein the reverse input cutoff clutch includes a biasing member that elastically biases the engagement element in a direction that brings the pressing surface closer to the pressed surface. the controller has the first function;
2. The suspension system according to claim 1 , further comprising a speed sensor for measuring a rotation speed of the clutch input member, a stroke sensor for measuring the vehicle height, and/or an angle sensor for measuring a rotation angle of the clutch input member. 2. The suspension system according to claim 1, further comprising a damper having a cylinder supported against the wheel and a piston supported against the vehicle body and fitted in the cylinder , the damper being disposed in parallel with the spring between the vehicle body and the wheel. A spring seat is provided that is supported so as to be movable vertically relative to the cylinder but not to be rotated relative to the cylinder,
The spring is configured by a coil spring elastically sandwiched between the vehicle body and the spring seat,
9. The suspension of claim 8, wherein the spring adjustment mechanism is configured to convert rotational movement of the clutch output member into upward and downward movement of the spring seat relative to the cylinder. the spring adjustment mechanism includes a nut having an outer diameter side ball screw groove on an inner circumferential surface thereof and being rotationally driven based on the rotation of the clutch output member, and a plurality of balls rollably disposed between the inner diameter side ball screw groove and the outer diameter side ball screw groove provided on an outer circumferential surface of the cylinder or an outer circumferential surface of a member supported and fixed to the cylinder,
10. The suspension device according to claim 9, wherein the nut is supported so as to be movable up and down and rotatable relative to the cylinder, and so as to be movable up and down integrally with the spring seat. The spring is constituted by a torsion bar,
2. The suspension system of claim 1 , wherein the spring adjustment mechanism is configured to rotate the torsion bar with rotation of the clutch output member. A spring provided so as to span between the vehicle body and the wheels;
a reverse input cut-off clutch that has an electric motor having a motor output shaft, a clutch input member that is rotationally driven based on the rotation of the motor output shaft, and a clutch output member, and that transmits the rotational torque input to the clutch input member to the clutch output member when a rotational torque is input to the clutch input member, but does not transmit the rotational torque reversely input to the clutch output member to the clutch input member when a rotational torque is reversely input to the clutch output member; and a spring adjustment mechanism that moves or rotates the spring in a vertical direction in accordance with the rotation of the clutch output member, and adjusts the vehicle height, which is the height of the vehicle body from the ground surface of the wheels, by moving or rotating the spring in a vertical direction by the spring adjustment mechanism based on the rotational driving of the motor output shaft;
A method for controlling a suspension system comprising:
A method for controlling a suspension system, when starting control to adjust the vehicle height in a direction to rotate the clutch input member in the same direction as the direction of the rotational torque being reversely input to the clutch output member from a state in which the reverse input cut-off clutch is locked due to a rotational torque being reversely input to the clutch output member, the method includes starting the motor output shaft at a first rotational acceleration, and switching the rotational acceleration of the motor output shaft to a second rotational acceleration smaller than the first rotational acceleration when the rotational speed of the clutch input member becomes greater than a predetermined first threshold value. The method for controlling a suspension system according to claim 12, wherein the motor output shaft is controlled by speed control or position control. The method for controlling a suspension system according to claim 12, wherein the motor output shaft is controlled by torque control when the rotational speed of the clutch input member is within the range from the start of the motor output shaft to the predetermined first threshold, and the motor output shaft is controlled by speed control or position control after the rotational speed of the clutch input member becomes greater than the predetermined first threshold. A spring is provided so as to span between the vehicle body and a member supporting the wheel;
a reverse input cut-off clutch that has an electric motor having a motor output shaft, a clutch input member that is rotationally driven based on the rotation of the motor output shaft, and a clutch output member, and that transmits the rotational torque input to the clutch input member to the clutch output member when a rotational torque is input to the clutch input member, but does not transmit the rotational torque reversely input to the clutch output member to the clutch input member when a rotational torque is reversely input to the clutch output member; and a spring adjustment mechanism that moves or rotates the spring in a vertical direction in accordance with the rotation of the clutch output member, and adjusts the vehicle height, which is the height of the vehicle body from the ground surface of the wheels, by moving or rotating the spring in a vertical direction by the spring adjustment mechanism based on the rotational driving of the motor output shaft;
A method for controlling a suspension system comprising:
A control method for a suspension system, comprising: setting a target value of the rotational speed of the clutch input member to 0 when the direction of the rotational torque being reversely input to the clutch output member is the same as the rotational direction of the clutch input member at a stage at which control to adjust the vehicle height is completed and the rotational speed of the clutch input member becomes equal to or lower than a predetermined second threshold value.

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