JP2011225176A - Vehicular steering device - Google Patents

Abstract

The present invention provides a vehicle steering apparatus that can perform backup during a failure relatively easily with a configuration in which a steering mechanism and a steering mechanism are completely separated mechanically.
In a steer-by-wire vehicle steering apparatus 1 in which a steering mechanism 2 and a steering mechanism 4 are mechanically separated, a backup motor 24 is connected to a steering shaft 22 and a backup motor 45 is connected to a pinion shaft 43. To do. When an abnormality occurs in the steer-by-wire function, the backup motor 24 and the backup motor 45 are electrically connected via the connection circuit 5 and the connection cables 6A and 6B. As a result, the steering mechanism 2 and the steering mechanism 4 are electrically connected to ensure a minimum steering function when an abnormality occurs.
[Selection] Figure 1

Description

  The present invention relates to a so-called steer-by-wire vehicle steering apparatus that includes a steering mechanism that steers a vehicle and a steering mechanism that is mechanically separated from the steering mechanism and steers steered wheels.

As a conventional vehicle steering device, there is a steer-by-wire vehicle steering device in which a steering mechanism and a steering mechanism are mechanically separated. In this type of vehicle steering apparatus, since the steering mechanism and the steering mechanism are not mechanically connected, fail-safe is necessary when the steer-by-wire function is abnormal.
As a general backup method, when an abnormality occurs, the steering mechanism and the steering mechanism are mechanically connected by an electromagnetic clutch, power is transmitted from the steering mechanism to the steering mechanism using a wire pulley, or electrical In some cases, both wheels of the vehicle are controlled and the assist mechanism is doubled (see, for example, Patent Documents 1 to 4).

JP 2008-126752 A JP 2002-120636 A JP 2003-63373 A Japanese Patent Laid-Open No. 10-329743

However, the configuration in which the steering mechanism and the steering mechanism are mechanically connected by a shaft or the like at the time of a failure is an inexpensive backup method, but has the advantage of steer-by-wire that mechanically separates the steering mechanism and the steering mechanism. I can't do it. On the other hand, if the steering mechanism and the steering mechanism are mechanically completely separated from each other, an expensive and complicated mechanism is required, for example, it is necessary to double the backup at the time of failure.
SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle steering apparatus that can perform backup at the time of failure relatively easily with a configuration in which a steering mechanism and a steering mechanism are completely separated from each other.

  In order to solve the above problems, a vehicle steering apparatus according to a first aspect includes a steering mechanism having a steering wheel and a steering reaction force actuator that applies a steering reaction force to the steering wheel, a steered wheel, and a steered wheel. A steering apparatus for a vehicle, comprising: a steering actuator that steers and mechanically separated from the steering mechanism; and a control unit that drives and controls the steering reaction force actuator and the steering actuator. A first electric motor having a rotating shaft connected to a steering shaft coupled to the steering wheel; and a rotating shaft connected to a turning shaft for turning a wheel; A second electric motor connectable to the first electric motor and the second electric motor when the control means malfunctions, and a connecting means for electrically connecting the first electric motor and the second electric motor. It is characterized in that to obtain.

According to a second aspect of the present invention, there is provided the vehicle steering apparatus according to the first aspect, wherein each of the first electric motor and the second electric motor is a DC motor with a brush.
Furthermore, the vehicle steering apparatus according to claim 3 is characterized in that, in the invention according to claim 1, the first electric motor and the second electric motor are each a brushless DC motor.

According to a fourth aspect of the present invention, in the vehicle steering apparatus according to any one of the first to third aspects, the first electric motor is a steering reaction force motor that constitutes the steering reaction force actuator. It is characterized by.
Furthermore, the vehicle steering apparatus according to claim 5 is the invention according to any one of claims 1 to 4, wherein the second electric motor is a steering motor that constitutes the steering actuator. It is a feature.
According to a sixth aspect of the present invention, there is provided the vehicle steering apparatus according to any one of the first to fifth aspects, wherein the first electric motor and the second electric motor each have a high induced voltage characteristic. It is characterized by being.

  According to the present invention, when an abnormality occurs in the steer-by-wire function, the backup motor connected to the steering shaft and the backup motor connected to the steered shaft are electrically connected to each other. The generated back electromotive force can be transmitted to a backup motor connected to the steered shaft. Therefore, when an abnormality occurs, the steering force by the driver can be transmitted to the steering mechanism. In this way, by making it possible to electrically connect the steering mechanism and the steering mechanism that are completely separated from each other, it is possible to easily perform backup during a failure without using a complicated configuration.

It is a whole lineblock diagram showing one embodiment of the present invention. 4 is a flowchart showing a steer-by-wire control processing procedure executed by a controller 10. It is a figure which shows the OFF state of the connection circuit. It is a figure which shows the ON state of the connection circuit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
(Constitution)
FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.
In the figure, reference numeral 1 denotes a steer-by-wire vehicle steering device. The vehicle steering apparatus 1 includes a steering mechanism 2 that is steered by a driver, and a steering mechanism 4 that is mechanically separated from the steering mechanism 2 to steer left and right front wheels (steered wheels) 3R and 3L.

The steering mechanism 2 includes a steering wheel 21, a steering shaft (steering shaft) 22 that is connected to the steering wheel 21 and transmits a steering force applied by a driver, a reaction force motor 23, and a backup motor 24. The
The reaction force motor 23 is for applying a steering reaction force to the steering wheel 21 by applying a torque to the steering shaft 22, and is constituted by a brushless motor or the like. Further, the backup motor 24 is constituted by a brushed DC motor, and its rotating shaft is connected to the steering shaft 22.

The steered mechanism 4 includes a rack shaft 41 coupled to the steered wheels 3R and 3L, a pinion gear 42 meshing with the rack shaft 41, a pinion shaft (steered shaft) 43 coupled to the pinion gear 42, and a steered motor 44. And a backup motor 45.
The steered motor 44 is used to steer the steered wheels 3R and 3L via the rack shaft 41 and the pinion gear 42 by rotationally driving the pinion shaft 43. As with the reaction force motor 23, a brushless motor or the like is used. Consists of. Similarly to the backup motor 24, the backup motor 45 is configured by a brushed DC motor, and its rotation shaft is coupled to the pinion shaft 43.

  The steering shaft 22 is provided with a steering torque sensor 11 and a steering angle sensor 12. The steering torque sensor 11 detects a steering torque transmitted from the steering wheel 21 to the steering shaft 22. The steering angle sensor 12 detects the rotation angle of the steering shaft 22 as a steering angle. Furthermore, the vehicle steering apparatus 1 includes a turning angle sensor 13 and a vehicle speed sensor 14. The steered angle sensor 13 detects the steered angles of the steered wheels 3R and 3L, and the vehicle speed sensor 14 detects the vehicle speed of the host vehicle. Each of these detection signals is input to the controller 10.

Then, the controller 10 drives and controls the steered motor 44 so as to steer the steered wheels 3R and 3L according to the steering angle of the steering wheel 21 based on the input detection signals. The reaction force motor 23 is driven and controlled so that a steering reaction force corresponding to a road surface reaction force corresponding to the 3L steering is applied to the steering wheel 21.
In addition, the vehicle steering apparatus 1 includes a connection circuit 5 and connection cables 6A and 6B that can electrically connect the backup motor 24 and the backup motor 45. The connection circuit 5 includes, for example, a relay that connects / disconnects the connection cable 6 </ b> A, and is ON / OFF controlled according to a control signal from the controller 10.

  In a normal state where no abnormality has occurred in the steer-by-wire function, the connection circuit 5 is turned off as shown in FIG. In this state, the backup motor 24 and the backup motor 45 do not affect each other. On the other hand, when an abnormality occurs in the steer-by-wire function, the connection circuit 5 switches to an on state as shown in FIG. 4 according to a control signal from the controller 10. In this state, the backup motor 24 and the backup motor 45 are electrically connected, and the back electromotive force generated in the backup motor 24 when the backup motor 24 rotates is transmitted to the backup motor 45. Become.

  That is, the controller 10 inputs detection signals detected by various sensors, and in a normal state where no abnormality has occurred in the steer-by-wire function, the controller 10 converts the steering angle detected by the steering angle sensor 12 and the vehicle speed detected by the vehicle speed sensor 14. A target turning angle is calculated by multiplying the gear ratio set accordingly. Then, based on the deviation between the calculated target turning angle and the actual turning angle detected by the turning angle sensor 13, the steering motor 44 is driven and controlled so that the actual turning angle matches the target turning angle. . Further, in this normal state, the controller 10 calculates a target reaction force torque by referring to a reaction force map or the like based on the steering angle detected by the steering angle sensor 12 and the vehicle speed detected by the vehicle speed sensor 14. Then, the reaction force motor 23 is driven and controlled based on the deviation between the target reaction force torque and the steering torque detected by the steering torque sensor 11. In this way, normal steer-by-wire control is performed.

On the other hand, in the abnormality occurrence state in which an abnormality has occurred in the steer-by-wire function, the controller 10 outputs a control signal for connecting the backup motor 24 and the backup motor 45 to the connection circuit 5 and described above. The drive control of the reaction force motor 23 and the steering motor 44 in the normal state is not performed.
It should be noted that the state in which the steer-by-wire function has an abnormality means that an abnormality has occurred in any of the sensors 11 to 14, the driving circuit of the reaction force motor 23 and the steering motor 44, the microcomputer, the ECU, and the power supply system. This is a state where normal steer-by-wire control cannot be performed normally.

FIG. 2 is a flowchart showing a steer-by-wire control process procedure executed by the controller 10.
This steer-by-wire control process is repeatedly executed every predetermined time. First, in step S1, the controller 10 reads various data and proceeds to step S2. Here, the steering torque detected by the steering torque sensor 11, the steering angle detected by the steering angle sensor 12, the turning angle detected by the turning angle sensor 13, and the vehicle speed detected by the vehicle speed sensor are acquired.

In step S2, the controller 10 performs abnormality determination of the steer-by-wire function. Here, as described above, whether or not an abnormality has occurred in any of the various sensors 11 to 14, the drive circuit of the reaction force motor 23 and the steering motor 44, the microcomputer, the ECU, and the power supply system. Determine. If it is determined that no abnormality has occurred and the steer-by-wire control can be normally performed, the process proceeds to step S3. If it is determined that an abnormality has occurred, the process proceeds to step 4 described later. Transition.
In step S3, the controller 10 performs normal steer-by-wire control and ends the steer-by-wire control process. That is, the reaction force motor 23 and the turning motor 44 are driven and controlled based on the detection signals of the various sensors acquired in step S1.

Further, in step S4, the controller 10 outputs a control signal for electrically connecting the backup motor 24 and the backup motor 45 to the connection circuit 5, and at the same time, a reaction force motor in normal steer-by-wire control. 23 and the steering motor 44 are stopped, and the steer-by-wire control process is terminated.
In FIG. 1, the reaction force motor 23 corresponds to the steering reaction force actuator, the turning motor 44 corresponds to the turning actuator, the controller 10 corresponds to the control means, and the backup motor 24 corresponds to the first electric motor. Correspondingly, the backup motor 45 corresponds to the second electric motor, and the connection circuit 5 corresponds to the connection means.

(Operation)
Next, the operation of the present embodiment will be described.
Assume that no abnormality has occurred in any of the various sensors 11 to 14, the motor drive circuit, the microcomputer, the ECU, and the power supply system. In this case, the controller 10 determines that the steer-by-wire function is in a normal state (No in step S2 in FIG. 2), and performs normal steer-by-wire control (step S3).

That is, when the driver operates the steering wheel 21, a steering angle detection signal corresponding to the steering angle is output from the steering angle sensor 12 accordingly. The controller 10 calculates a target turning angle according to the steering angle and the vehicle speed detected by the vehicle speed sensor 14, and drives and controls the turning motor 44 so that the actual turning amount becomes the calculated target turning angle. To do. Thereby, the steered wheels 3R and 3L are steered.
At this time, a road surface reaction force corresponding to the turning of the steered wheels 3R and 3L is generated. Therefore, the controller 10 drives and controls the reaction force motor 23 so that the steering torque detected by the steering torque sensor 11 becomes the target reaction force torque for applying the steering reaction force corresponding to the road surface reaction force. Thereby, a steering reaction force is applied to the steering wheel 21.

In this way, normal steer-by-wire control is performed, and the driver can perform a steering operation that matches his / her sense.
When the steer-by-wire function is in a normal state, the connection circuit 5 is in an off state as shown in FIG. 3, so that the backup motor 24 and the backup motor 45 do not affect each other. .

  For example, it is assumed that an abnormality has occurred in the steering torque sensor 11 from this state. Then, the controller 10 is in a state where the steer-by-wire control cannot be normally performed, and determines that the steer-by-wire function is in an abnormal state (Yes in step S2). Therefore, the controller 10 outputs a control signal for setting the connection cable between the backup motor 24 and the backup motor 45 to the connection circuit 5 (step S4). Thereby, as shown in FIG. 4, the connection circuit 5 switches to an ON state. As described above, the backup motor 24 having the rotation shaft coupled to the steering shaft 22 and the backup motor 45 having the rotation shaft coupled to the pinion shaft 43 are electrically connected.

  At this time, when the driver operates the steering wheel 21, the steering force is transmitted to the steering shaft 22, and the backup motor 24 connected to the steering shaft 22 rotates in conjunction therewith. At this time, when the backup motor 24 rotates, a back electromotive force is generated in the backup motor 24. Since the backup motor 24 and the backup motor 45 are electrically connected, the back electromotive force generated by the backup motor 24 is transmitted to the backup motor 45 via the connection circuit 5 and the connection cables 6A and 6B. The backup motor 45 rotates. Thereby, the steered wheels 3R and 3L are steered.

  As described above, when an abnormality occurs in the steer-by-wire function, the backup motor 24 connected to the steering shaft 22 and the backup motor 45 connected to the pinion shaft 43 are electrically connected to each other to be mechanically separated. The steering mechanism and the steering mechanism are electrically connected. As a result, the minimum left-right steering function of the vehicle can be provided to the driver.

  By the way, in a steer-by-wire type vehicle steering device, in order to prevent the steering wheel from slipping when an abnormality occurs, a method of mechanically connecting the steering mechanism and the steering mechanism when an abnormality occurs is used. ing. However, in this case, the advantage of steer-by-wire that mechanically separates the steering mechanism and the steering mechanism cannot be fully utilized. On the other hand, when the steering mechanism and the steering mechanism are mechanically completely separated from each other, it is necessary to provide a complete duplex system for backup when an abnormality occurs, resulting in an expensive and complicated mechanism.

  On the other hand, in this embodiment, the steering mechanism and the steering mechanism are mechanically separated from each other, and when an abnormality occurs, a backup motor connected to the steering shaft and the pinion shaft is used. Electrical connection with the steering mechanism. Therefore, it is possible to perform backup at the time of failure with an inexpensive configuration while taking advantage of the steer-by-wire that mechanically separates the steering mechanism and the steering mechanism.

(effect)
As described above, in the above-described embodiment, the backup motor is connected to the steering shaft (steering shaft) and the pinion shaft (steering shaft), and these backup motors are electrically connected when an abnormality occurs in the steer-by-wire function. Thus, the back electromotive force of the backup motor connected to the steering shaft can be transmitted to the backup motor connected to the steered shaft.
Therefore, when the driver performs a steering operation when an abnormality occurs, the steering force by the driver can be transmitted to the steering mechanism, and a minimum steering function can be provided. Therefore, it is possible to perform backup at the time of failure with an inexpensive and simple configuration while taking advantage of the steer-by-wire that mechanically separates the steering mechanism and the steering mechanism.

  Further, since the backup motor is constituted by a brushed DC motor, it is possible to effectively transmit the steering force from the steering mechanism to the steering mechanism at the time of backup. At this time, if a high induced voltage type with a relatively large induced voltage constant is used as the backup motor, the transmission efficiency is good, a stronger steering force can be obtained when an abnormality occurs, and the current flowing through the connected wiring is kept low. Therefore, it is possible to use a wiring that is thin, lightweight, inexpensive, and easy to install as the connection cable.

(Application examples)
In the above embodiment, the case where the backup motor is configured by a brushed DC motor has been described. However, the backup motor may be configured by a brushless DC motor. In this case, it is desirable that the induced voltage is set to be very large and the position vector of the motor follows the current vector generated by the rotation of the motor on the handle side even with a slight rotation.

  In the above embodiment, the case where the backup motor 24 is provided separately from the reaction force motor 23 that applies the steering reaction force to the steering wheel 21 has been described. However, the reaction force motor 23 may be used as a backup motor on the handle side. it can. Similarly, the steered motor 44 can be used as a backup motor on the steered wheel side. In this case, when an abnormality occurs, the reaction force motor 23 and the turning motor 44 are electrically connected. As a result, backup at the time of failure can be performed with a simpler configuration.

  DESCRIPTION OF SYMBOLS 1 ... Steering device for vehicles, 2 ... Steering mechanism, 3R, 3L ... Steering wheel, 4 ... Steering mechanism, 5 ... Connection circuit, 6A, 6B ... Connection cable, 10 ... Controller, 11 ... Steering torque sensor, 12 ... Steering Angle sensor, 13 ... Steering angle sensor, 14 ... Vehicle speed sensor, 21 ... Steering wheel, 22 ... Steering shaft, 23 ... Reaction force motor, 24 ... Backup motor, 41 ... Rack shaft, 42 ... Pinion gear, 43 ... Pinion shaft, 44 ... steering motor, 45 ... backup motor

Claims (6)

A steering mechanism having a steering wheel and a steering reaction force actuator for applying a steering reaction force to the steering wheel; a steered wheel and a steering actuator for turning the steered wheel; and mechanically separated from the steering mechanism. A vehicle steering apparatus comprising: a steering mechanism; and a control means for driving and controlling the steering reaction force actuator and the steering actuator,
A first electric motor having a rotating shaft connected to a steering shaft coupled to the steering wheel;
A second electric motor having a rotating shaft connected to a steered shaft that steers a wheel and electrically connectable to the first electric motor;
A vehicle steering apparatus comprising: connection means for electrically connecting the first electric motor and the second electric motor when the control means malfunctions.   2. The vehicle steering apparatus according to claim 1, wherein each of the first electric motor and the second electric motor is a DC motor with a brush.   The vehicle steering apparatus according to claim 1, wherein each of the first electric motor and the second electric motor is a brushless DC motor.   The vehicle steering apparatus according to any one of claims 1 to 3, wherein the first electric motor is a steering reaction force motor constituting the steering reaction force actuator.   The vehicle steering apparatus according to any one of claims 1 to 4, wherein the second electric motor is a steering motor that constitutes the steering actuator.   The vehicle steering apparatus according to any one of claims 1 to 5, wherein each of the first electric motor and the second electric motor is an electric motor having a high induced voltage characteristic.

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