JP2001047839A - Vehicle suspension device - Google Patents

Abstract

(57) [Problem] To provide a vehicle in which the right and left hydraulic cylinders communicate with each other to ensure good grounding of wheels, when traveling straight ahead, when changing from turning to straight traveling, and when traveling straight and at high speed. The vehicle body is attenuated in a short period of time from side to side when the vehicle receives a side wind. SOLUTION: Hydraulic cylinders 11a, 11 at left wheel position
c and the right wheel positions 11b and 11d are connected via oil passages P1 and P2, respectively, and the oil passages P1 and P2 are provided with gate valves 17 and 18 that are normally in a communication state. The gate valves 17 and 18 are switched to a non-communication state when the vehicle is turning, and even when the vehicle is traveling straight, it is detected or estimated that the vehicle body BD having a low frequency has rolled to the left and right. Is switched to the non-communication state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pair of hydraulic cylinders at right and left wheel positions among a plurality of hydraulic cylinders provided between a wheel and a vehicle body for each wheel position to attenuate vertical vibration of the vehicle body. The present invention relates to a vehicle suspension device that communicates with a vehicle.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Patent Laid-Open Publication No. 6-206, valve means capable of changing the degree of communication between the same pair of hydraulic cylinders is provided in an oil passage connecting the pair of hydraulic cylinders at the left and right wheel positions. 2. Description of the Related Art There is known a suspension apparatus for a vehicle that maintains a high degree of communication of the means and controls the degree of communication to decrease as the vehicle speed and the steering angle increase when the vehicle is turning.

[0003]

SUMMARY OF THE INVENTION In a vehicle suspension apparatus for controlling the degree of communication between left and right hydraulic cylinders of this type, the greater the degree of communication, the better the grounding of the wheels, but when the vehicle body rolls, In addition, there is a problem that the roll cannot be accurately attenuated in a short time due to a response delay due to piping between the left and right hydraulic cylinders. In addition, the roll of the vehicle body from side to side is mainly
When the vehicle changes from straight running to turning, when the turning radius of the vehicle changes, when the vehicle changes from turning to straight running,
Occurs when a vehicle running at high speed receives a crosswind.

However, in the above-described conventional apparatus, the degree of communication between the left and right hydraulic cylinders is reduced during turning of the vehicle. Therefore, when the vehicle body changes from straight running to turning, the turning radius of the vehicle is reduced. Can be attenuated in a short period of time when the vehicle rolls from side to side when changing, but when the vehicle changes from turning to straight running, and when a vehicle running straight and running at high speed receives a side wind, When the vehicle body rolls left and right, the roll cannot be attenuated in a short time. This rolling gives the occupant a feeling of anxiety, and should be stopped promptly from the viewpoint of the riding comfort of the vehicle. In order to attenuate this rolling in a short period of time, it is conceivable to set the damping force of each hydraulic cylinder to a large value. However, this gives the occupant a periodic upward feeling (so-called lumpy feeling) due to unevenness of the road surface. This is also uncomfortable for the crew. Furthermore, if the communication between the left and right hydraulic cylinders is completely abolished, good grounding of the wheels due to the communication between the hydraulic cylinders cannot be enjoyed.

SUMMARY OF THE INVENTION The present invention has been made to address the above-mentioned problem, and an object of the present invention is to enjoy good grounding of wheels by connecting left and right hydraulic cylinders, and then proceed straight from turning of the vehicle. It is an object of the present invention to provide a suspension apparatus for a vehicle that can attenuate a lateral swing of a vehicle body, which is generated when the vehicle is traveling and when a vehicle traveling straight and running at a high speed receives a crosswind, in a short time.

In order to achieve this object, a structural feature of the present invention is that a plurality of hydraulic cylinders provided between the wheel and the vehicle body at each wheel position to attenuate vertical vibration of the vehicle body are provided. A valve means provided in an oil passage connecting a pair of hydraulic cylinders at left and right wheel positions among a plurality of hydraulic cylinders and capable of changing a degree of communication between the same pair of hydraulic cylinders, and detecting a turning traveling state of the vehicle Control to reduce the degree of communication of the valve means during the detection.
(1) In a vehicle suspension device provided with a control means, the occurrence of lateral sway of a vehicle body having a low frequency when the vehicle travels straight ahead is detected or estimated, and the communication degree of the valve means is detected or estimated at the time of the detection or estimation. That is, the second control means for performing control is provided on the smaller side.

In this case, the second control means may control the low frequency of the vehicle when the vehicle is traveling straight ahead based on the difference between the motion state quantities representing the vertical motion of the vehicle body at the left and right wheel positions when the vehicle is traveling straight. It may be configured to detect the occurrence of lateral swaying of the vehicle body having the above, and to control the degree of communication of the valve means to be smaller at the time of the detection. Further, the second control means may control the occurrence of lateral sway of the vehicle body having a low frequency during the straight running of the vehicle, on condition that the vehicle speed in the straight running of the vehicle is higher than or equal to a predetermined speed. May be estimated, and at the time of the estimation, control may be performed to reduce the degree of communication of the valve means.

According to the present invention having the above-described structure, the second control means detects or estimates the occurrence of the lateral swing of the vehicle body having a low frequency when the vehicle is traveling straight ahead, Since the control is performed to reduce the degree of communication of the valve means at the time of estimation, the vehicle body rolls to the left and right when the vehicle changes from turning to straight running and when a vehicle running at high speed and straight travel receives a crosswind. , The roll can be attenuated in a short time, so that the occupant does not have anxiety and the ride comfort of the vehicle is improved. In addition, at least when the vehicle is traveling straight except for the above case,
Since the degree of communication between the left and right hydraulic cylinders can be kept large, good grounding of the wheels can also be enjoyed.

In the above description, the degree of communication between the left and right hydraulic cylinders indicates the size of the opening area of the oil passage between the two hydraulic cylinders including the non-communicating state. And
Controlling the degree of communication between the left and right hydraulic cylinders to a side that reduces the degree of communication means that, in valve means that can change the degree of communication (opening area) continuously or stepwise, the degree of communication is reduced including non-communication. This means that the valve means that can selectively change communication and non-communication means to switch to the non-communication side. When the communication degree is reduced, the communication degree may be continuously controlled to a smaller side or may be controlled intermittently to a smaller side.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a vehicle suspension device according to the present invention.

This suspension device is interposed between a not-shown wheel (unsprung member) and a vehicle body (sprung member) BD at each of the left and right front wheels and the left and right rear wheels (not shown). Sealed hydraulic cylinders 11a to 11d
It has. The lower ends of the hydraulic cylinders 11a to 11d are connected to lower arms belonging to unsprung members via bushes 12a to 12d, and piston rods 13a to 13d project from the upper surfaces of the cylinders 11a to 11d so as to be able to advance and retreat. Is connected to the vehicle body BD. Pistons 14a to 14d are provided at the lower ends of these piston rods 13a to 13d, respectively.
14d slides on the inner peripheral surface of the hydraulic cylinders 11a to 11d in a liquid-tight manner in the axial direction. Piston rods 13a to 13
d and the pistons 14a to 14d are provided with internal passages that penetrate in the axial direction and communicate with the respective oil chambers of the hydraulic cylinders 11a to 11d.

The internal passages of the piston rods 13a to 13d are provided with a variable throttle valve 15 whose passage area can be changed electrically.
Via a through d, the bladder communicates with each of the oil chambers of the accumulators 16a through 16d partitioned into an air chamber and an oil chamber. The oil chambers of the accumulators 16a and 16b communicate with each other via an oil passage P1, and a gate valve 17 is interposed in the oil passage P1. The oil chambers of the accumulators 16c and 16d also communicate with each other via an oil passage P2, and a gate valve 18 is interposed in the oil passage P2. Each of the gate valves 17 and 18 is constituted by an electromagnetic switching valve, and is set to a communication state (shown state) in a non-energized state, and is set to a non-communication state in an energized state.

The oil passages P1 and P2 are provided with a leveling valve 2
They are connected to a hydraulic oil supply / discharge device via oil passages P3 and P4 in which the first and the second 22 are interposed. Leveling valve 2
Numerals 1 and 22 are also constituted by electromagnetic switching valves, and are respectively set to a non-communicating state (illustrated state) in a non-energized state and to a communicating state in an energized state.

The hydraulic oil supply / discharge device includes a hydraulic pump 24 driven by an electric motor 23. The hydraulic pump 24 pumps up hydraulic oil from the reservoir tank 25 at the time of its operation, and discharges the hydraulic oil to the oil paths P3 and P4 via an oil path P5 to which an accumulator 26 is connected. Between the oil passage P5 and the reservoir tank 25, a discharge valve 27 for connecting the oil passage P5 to the reservoir tank 25 in a communication state is connected. The discharge valve 27 is also formed of an electromagnetic switching valve, and is set to a non-communication state (shown state) in a non-energized state and to a communication state in an energized state.

Further, the suspension device includes an electric control unit 31 composed of a microcomputer or the like.
It also has. The electric control unit 31 repeatedly executes a program corresponding to the flowchart shown in FIG. 2 every short time, and various valves 15a to 15d, 17, 18,
21, 22, 27 and the electric motor 23 are controlled. The electric control unit 31 includes a vehicle speed sensor 32,
Steering angle sensor 33, oil pressure sensor 34, vehicle height sensor 35a-
35d and the acceleration sensors 36a to 36d are also connected.

A vehicle speed sensor 32 detects a vehicle speed V, a steering angle sensor 33 detects a steering angle θ of a steering wheel (not shown), and a hydraulic pressure sensor 34 detects a hydraulic pressure P in an oil passage P5. The steering angle θ is represented by “0” when the vehicle is in a straight running state, and the steering amount to the left and right is represented by positive and negative signs and the magnitude of the absolute value. The vehicle height sensors 35a to 35d are each constituted by a stroke sensor or the like connected between the vehicle body BD and an unsprung member such as a lower arm at each wheel position.
The vertical displacements (so-called vehicle heights) Xa to Xd of D are detected, respectively. Note that the displacement amounts Xa to Xd each represent a reference displacement amount (reference vehicle height value) by “0”, and the upper and lower displacement amounts with respect to the reference displacement amount are represented by positive and negative signs and magnitudes of absolute values. The acceleration sensors 36a to 36d are respectively assembled to the vehicle body BD at the respective wheel positions, and detect the absolute vertical accelerations Ga to Gd of the vehicle body BD, respectively. The accelerations Ga to Gd represent the acceleration in the vertical direction by positive and negative signs and the magnitude of the absolute value. In addition, these displacement amounts Xa to Xd and accelerations Ga to Gd respectively represent the amount of vertical movement of the vehicle body BD.

Next, the operation of the embodiment configured as described above will be described with reference to the flowchart of FIG. When an ignition switch (not shown) is turned on, the electric control unit 31 causes steps 100 to 100 of the program in FIG.
The process consisting of 126 is repeatedly executed at predetermined short intervals.

In the execution of this program, after the start in step 100, in step 102, if the oil pressure P detected by the oil pressure sensor 34 is lower than a predetermined oil pressure, the electric motor 23 is operated to activate the hydraulic pump 24. By driving, the detected oil pressure P falls within a predetermined range.

After the processing of step 102, step 1
At 04, the vehicle height at each wheel position is changed according to the selection by the driver, adjusted according to changes in the occupant and the loaded luggage, or changed according to the vehicle speed V. When increasing the vehicle height, the electric control unit 31 controls the vehicle height sensors 35a to 35a.
The hydraulic pump 24 is driven by operating the electric motor 23 until the displacement amounts (vehicle heights) Xa to Xd detected by 35d increase to vehicle heights corresponding to the above conditions, respectively. By energizing, the valves 21 and 22 are switched to the communicating state. The gate valves 17 and 18 are normally in a communication state. This allows
Hydraulic oil discharged from the hydraulic pump 24 is supplied to the oil passages P5, P
3, P4, leveling valves 21, 22, oil passages P1, P
2. Gate valves 17, 18 and variable throttle valve 15c
To the oil chambers of the hydraulic cylinders 11a to 11d, respectively, and the vehicle body BD at each wheel position is lifted. When lowering the vehicle height, the electric control unit 31 controls the discharge valve until the displacement amounts (vehicle heights) Xa to Xd detected by the vehicle height sensors 35a to 35d decrease to the vehicle heights according to the above conditions. The valve 27 is switched to the communicating state by energizing the valve 27, and the valves 21 and 22 are switched to the communicating state by energizing the leveling valves 21 and 22. Thereby, the hydraulic cylinders 11a to 11d
The hydraulic oil in each oil chamber of the variable throttle valves 15c to 15c
d, discharged to the reservoir tank 25 via the gate valves 17 and 18, the oil passages P1 and P2, the leveling valves 21 and 22, the oil passages P3, P4 and P5, and the discharge valve 27, and the vehicle body BD at each wheel position is lowered. .

After the processing in step 104, step 1
At 06, the damping force at each wheel position is controlled. In controlling the damping force, the vehicle speed V detected by the vehicle speed sensor 32, the steering angle θ detected by the steering angle sensor 33, and the displacement (vehicle height) X detected by the vehicle height sensors 35a to 35d.
a to Xd and the accelerations Ga to Gd detected by the acceleration sensors 36a to 36d,
Control amounts corresponding to the opening degrees a to 15d are calculated. Then, the electric control unit 31 controls the variable throttle valves 15a to 15a.
15d is energized and controlled in accordance with the calculated control amount, and the opening of the valves 15a to 15d is set and controlled in accordance with the vehicle speed V, steering angle θ, displacement (vehicle height) Xa to Xd and Ga to Gd. .

As described above, the variable throttle valves 15a to 15d
With the opening of the vehicle set and controlled, the vehicle body BD is moved to the lower arm,
When vertically vibrating with respect to an unsprung member such as a wheel, the hydraulic oil in each oil chamber of the hydraulic cylinders 11a to 11d is compressed with the compression and expansion of the gas in each gas chamber of the accumulators 16a to 16d. Piston rods 13a to 13d and variable throttle valves 15a to 15d
And the hydraulic oil in each of the accumulators 16a to 16d flows into the respective oil chambers of the accumulators 16a to 16d, and the hydraulic oil in the respective oil chambers of the accumulators 16a to 16d respectively follows the reverse paths to the respective oil chambers of the hydraulic cylinders 11a to 11d. Or flowing in. At this time, since the variable throttle valves 15a to 15d impart resistance to the flow of the hydraulic oil, the vibration of the vehicle body BD is suppressed. As will be described in detail later, if the gate valves 17 and 18 are in communication, the hydraulic cylinders 11a and 11c and the hydraulic cylinders 11b and 11d
Hydraulic oil flows back and forth between Gate valve 1
If the hydraulic cylinders 7 and 18 are not in communication, each hydraulic cylinder 11a
11d and each of the accumulators 16a to 16d is allowed to flow only between them.

After the processing in step 106, the electric control unit 31 performs the processing in steps 108 to 124
The communication and non-communication of the gate valves 17 and 18 are controlled according to the running state of the vehicle.

First, it is determined by the processing of steps 108 and 110 whether or not the vehicle is in a turning traveling state. In step 108, it is determined whether or not the vehicle speed V detected by the vehicle speed sensor 32 is equal to or higher than a predetermined vehicle speed V1 (for example, 10 km / h). In step 110, the absolute value | θ | of the steering angle θ detected by the steering angle sensor 33
Is greater than or equal to a predetermined steering angle θ0 (for example, a steering wheel steering angle of 5 degrees). If the vehicle is in a turning traveling state and the vehicle speed V is equal to or greater than the predetermined vehicle speed V1 and the absolute value | θ | of the steering angle θ is equal to or greater than the predetermined steering angle θ0, step 10 is executed.
At both steps 8 and 110, “YES” is determined, and the program proceeds to step 122.

In step 122, the electric control unit 31 switches the gate valves 17, 18 to a non-communicating state by energizing the gate valves 17, 18. In this state, the leveling valves 21 and 22 are kept in a non-communication state by the non-energization control. This allows
Between the oil chambers of the accumulators 16a and 16b via the oil passage P1, and the accumulators 16c and 16 via the oil passage P2.
The space between the oil chambers in d is controlled to be in a non-communication state. In this state, the hydraulic oil in each oil chamber of the hydraulic cylinders 11a to 11d and the accumulators 16a to 16d at each wheel position is:
Since it does not flow into the oil chambers of the hydraulic cylinders 11a to 11d and the accumulators 16a to 16d at other wheel positions, the inclination (roll) of the vehicle body BD can be reduced even when the vehicle is turning, and The vibration of the vehicle body BD due to the turning can also be attenuated in a short time by the damping action of the variable throttle valves 15a to 15d for each wheel position.

On the other hand, if the vehicle is not in a turning running state, "NO" is determined in step 108 or step 110, and the program proceeds to steps 112 to 116.
The processing of steps 112 to 116 is based on the difference in the amount of movement of the vehicle body BD in the vertical direction between the left and right wheel positions during the straight running of the vehicle. This is a process for detecting occurrence. In step 112, the vehicle speed sensor 32
It is determined whether or not the detected vehicle speed V is equal to or higher than a predetermined vehicle speed V2 (for example, 40 km / h) higher than the predetermined vehicle speed V1. If the vehicle speed V is lower than the predetermined vehicle speed V2,
At step 112, “NO” is determined, and the program proceeds to step 118. This is because when the vehicle speed is lower than the predetermined vehicle speed V2, it is difficult for the vehicle body BD having the low frequency to roll to the left and right, and even if the roll occurs, the occupant does not feel much anxiety and the communication control described later This is because the running stability of the vehicle should be emphasized by improving the contact property of each wheel.

If the vehicle speed V is equal to or higher than the predetermined vehicle speed V2, "YES" is determined in step 112, and in step 114, the difference between the displacement amounts Xa and Xb detected by the vehicle height sensors 35a and 35b is determined. Xab (= Xa-Xb) and the displacement Xc detected by the vehicle height sensors 35c and 35d,
The difference Xcd of Xd (= Xc-Xd) is calculated, and the average value (Xab + Xcd) / 2 of the differences Xab and Xcd is calculated.
In this step 114, in order to store a plurality of calculated average values (Xab + Xcd) / 2 retroactively in a memory built in the electric control unit 31,
The average value (Xab + Xcd) / 2 before a predetermined time or more is deleted from the memory, and the newly calculated average value (Xab + Xc) is deleted.
d) / 2 is stored in the memory.

In step 116, a plurality of average values (Xab + Xcd) / 2 from the past to the present are read from the memory, and the average value (Xab + Xcd) / 2 is 1-2 Hz.
It is determined whether the frequency fluctuates at a low frequency and a predetermined amplitude or more. The average value (Xab + Xcd) / 2 is 1 to 2H
If it fluctuates at a low frequency of about z and a predetermined amplitude or more,
In step 116, "YES", that is, it is determined that the vehicle body BD is swaying left and right at a low frequency,
At 2, the non-communication control is executed. Therefore, if the vehicle is running straight and the vehicle body BD is swaying, the accumulators 16c and 16c between the oil chambers of the accumulators 16a and 16b via the oil passage P1 and the accumulators 16c and
Both oil chambers of 16d are controlled to be in a non-communication state, and for the same reason as described above, the vertical vibration of the vehicle body BD is suppressed for each wheel position, and the lateral vibration of the vehicle body BD is attenuated in a short time. Can be done.

The average value (Xab + Xcd) / 2 is 1 to 2H
If the frequency does not fluctuate at a low frequency of about z and the predetermined amplitude or more, "NO" is determined in step 116, that is, it is determined that the vehicle body BD does not roll left and right at the low frequency, and "NO" is determined in step 112. Then, the program proceeds to step 118 as in the case where it is determined that Step 118
Is a process of estimating the occurrence of lateral roll of the vehicle body BD having a low frequency during straight running, on condition that the vehicle speed in straight running is equal to or higher than a predetermined vehicle speed. Therefore, in step 118, the vehicle speed V detected by the vehicle speed sensor 32 is higher than the predetermined vehicle speed V2 by a predetermined vehicle speed V3 (for example, 60 km).
/ H) is determined. This is because, when the vehicle is traveling straight at a high speed equal to or higher than the predetermined vehicle speed V3, there is a high possibility that the vehicle body BD will cause lateral left and right sway due to disturbance such as slight cross wind.

If the vehicle speed V is equal to or higher than the predetermined vehicle speed V3, "YES" is determined in step 118, that is, the occurrence of the roll is estimated, and the program proceeds to step 120. In step 120, the acceleration sensors 36a to 36a to
36d, based on the accelerations Ga to Gd detected by
At each wheel position, it is determined whether or not vibration of about 3 or 4 Hz is generated in the vehicle body BD. This is because the vibration of the vehicle body BD of about 3 or 4 Hz or more is extremely uncomfortable for the occupant, and should be removed by the communication control described later in preference to the roll. It is. Therefore, only when the vehicle speed V is equal to or higher than the predetermined vehicle speed V3 and no vibration of about 3.4 Hz or more is generated in the vehicle body BD at any of the wheel positions, the determination in step 120 is “NO”. ,
The non-communication control processing of step 122 is executed.

As a result, when the vehicle is in a high-speed straight running state and the possibility that the vehicle body BD is swaying due to disturbance such as a cross wind is high, vibration of the vehicle body BD occurs at about 3.4 Hz or more. The oil path P1 between the oil chambers of the accumulators 16a and 16b and the oil path P
The two oil chambers of the accumulators 16c and 16d are controlled to be in a non-communication state through the second unit 2 for the same reason as described above.
Vertical movement of the vehicle body BD is suppressed at each wheel position, and the vehicle body BD
Can be attenuated in a short time.

On the other hand, "NO" in step 118, that is, the vehicle speed V is not higher than the predetermined vehicle speed V3, or step 12
If “YES” at 0, that is, if it is determined that the vibration of the vehicle body BD is about 3 or 4 Hz or more, the program proceeds to step 124. In step 124, the electric control unit 31 sets the gate valve 17,
By controlling the non-energization of the valve 18, the valves 17, 18
Is kept in communication. Thereby, between the oil chambers of the accumulators 16a and 16b via the oil passage P1 and the oil passage P2
Between the oil chambers of the accumulators 16c and 16d via
Each is controlled to be in a communication state. In this state, the hydraulic cylinders 11a and 11b at the front wheel position and the accumulator 1
The hydraulic oil in each of the oil chambers 6a and 16b flows into each other, and the hydraulic oil in each of the hydraulic chambers of the hydraulic cylinders 11c and 11d and the accumulators 16c and 16d at the rear wheel position also flows into each other. As a result, the grounding property of each wheel is maintained well, and the vibration of the vehicle body BD of about 3 or 4 Hz or more is absorbed and the occupant does not feel uncomfortable.

As can be understood from the above description of operation, according to the above-described embodiment, even when the vehicle is traveling straight, the processing of steps 112 to 122 allows the vehicle to change from turning to straight traveling, and to travel at high speed. Even if the vehicle in the middle receives a side wind, if the body BD rolls to the left or right,
Since the roll can be attenuated in a short time, the ride comfort of the vehicle is improved without the occupant feeling uneasy.
In addition, when the vehicle is running straight, except for the above case, the degree of communication between the left and right hydraulic cylinders can be kept large, so that good grounding of the wheels can be enjoyed, and
The vibration of about 4 Hz or more is absorbed, and the occupant does not feel uncomfortable.

In the above-described embodiment, the difference Xab between the displacements Xa and Xb detected by the vehicle height sensors 35a and 35b and the difference Xcd between the displacements Xc and Xd detected by the vehicle height sensors 35c and 35d. Average value of (Xab + Xcd) /
On the condition that 2 fluctuates at a low frequency of about 1 to 2 Hz and a predetermined amplitude or more, the lateral swing of the vehicle body BD is detected. However, instead of this, the difference Xab,
On the condition that one of Xcd fluctuates at a low frequency of about 1 to 2 Hz and a predetermined amplitude or more, the left and right swing of the vehicle body BD may be detected. In addition, the average value (Xab +
Xcd) / 2 or one of the differences Xab and Xcd may repeat the positive / negative at a low frequency of about 1 to 2 Hz, and the lateral swing of the vehicle body BD may be detected.

Further, for each of the differences Xab and Xcd, the roll of the vehicle body BD is detected separately for the front wheel position and the rear wheel position by the method of the above embodiment and the modified example, and the vehicle body at the front wheel position is detected based on the difference Xab. When the roll of the BD is detected, the gate valve 17 may be controlled to be disconnected, and when the roll of the vehicle body BD at the front wheel position is detected based on the difference Xcd, the gate valve 18 may be controlled to be disconnected.

Further, in the above-described embodiment and the modified example, the roll of the vehicle body BD is detected based on the displacement amounts (vehicle height) Xa to Xd, but the accelerations Ga to Gd detected by the acceleration sensors 35a to 35d are different from each other. Rolling of the vehicle body BD may be detected based on this. In this case, instead of the displacement amounts (vehicle heights) Xa to Xd in the above-described embodiment and the modified example, the acceleration G
a to Gd may be used. Further, instead of the displacement amounts (vehicle height) Xa to Xd, the same displacement amounts (vehicle height) Xa to Xd are used.
, Or the vertical velocities Va to Vd of the vehicle body BD obtained by integrating the accelerations Ga to Gd.

In the above-described embodiment, the roll of the vehicle body BD due to the side wind or the like is estimated at step 118 on condition that the vehicle speed V is equal to or higher than the predetermined vehicle speed V3. However, a sensor for actually detecting the crosswind is assembled to the vehicle body BD, and the detection of the crosswind equal to or more than a predetermined value by the sensor and the condition of the vehicle speed V are combined so that the roll of the vehicle body BD during the straight running at high speed is adjusted. May be estimated.

In the above embodiment, the gate valves 17 and 18 are continuously energized to maintain the non-communication state in step 122. However, in order to avoid a temperature rise due to the continuous energization, the gate valves 17 and 18 are not energized. The valves 17 and 18 may be intermittently controlled to be in non-communication.

In the above-described embodiment, the gate valve 17 is controlled to be in communication with the oil passages P1 and P2 for communicating the hydraulic cylinders 11a and 11c at the left wheel position with the hydraulic cylinders 11b and 11d at the right wheel position. , 18 are provided, and the gate valves 17, 18 are controlled to be in a non-communicating state in step 122, and the gate valves 17, 18 are controlled to be in a communicating state in step 124. However, a variable throttle valve is used in place of these gate valves 17 and 18, and in step 122, even if the oil passages P1 and P2 are not completely disconnected from each other, the same variable as in step 124 is used. The opening degree of the throttle valve may be controlled to be small. In short, in step 122, the degree of communication between the oil passages P1 and P2 may be set to a smaller state including non-communication than in step 124.

Further, when a variable throttle valve is used instead of the gate valves 17 and 18, the opening of the variable throttle valve is changed or estimated in accordance with the magnitude of the roll of the vehicle body BD. The opening degree of the variable throttle valve may be changed according to the magnitude of the roll of the vehicle body BD. In this case, the magnitude of the roll of the vehicle body BD is determined in step 116, and the control in step 122 is performed so as to decrease the opening of the variable throttle valve as the determined roll increases. I just need. Further, in step 118, the magnitude of the vehicle speed V that is equal to or higher than the predetermined vehicle speed V3 is determined, and by the processing in step 122, control is performed such that the opening degree of the variable throttle valve decreases as the determined vehicle speed V increases. I just need.

In the above embodiment, the time is not added to the condition for judging the vehicle body BD in steps 112 to 116 and the condition for estimating the vehicle body BD in step 118. The determination and the estimation condition can be made more accurate by adding time to the estimation condition and the estimation condition. In this case, step 112
The program may proceed to step 122 when the determination conditions of to 116 and the estimation condition of step 118 are continuously detected for a predetermined time or more.

Further, in the above embodiment, the discharge valve 27 is constituted by a valve which is electrically switched and controlled, but the discharge valve 27 may be constituted by a valve which can be mechanically switched. In this case, when the hydraulic oil needs to be discharged from the oil passage P3, the valve may be mechanically switched to the communication state.

In the above embodiment, the vehicle body BD
Vehicle height sensor 3 for detecting the amount of vertical movement of the vehicle
5a to 35d and the acceleration sensors 36a to 36d are provided, but both sensors 35a to 35d and 36a to 36d are provided.
One of the sensors d may be replaced with a sensor for estimating the motion state amount such as an observer.

[Brief description of the drawings]

FIG. 1 is an overall schematic view of a vehicle suspension device according to an embodiment of the present invention.

FIG. 2 is a flowchart of a program executed by the electric control unit of FIG. 1;

[Explanation of symbols]

BD: vehicle body, P1 to P5: oil passage, 11a to 11d: hydraulic cylinder, 13a to 13d: piston rod, 14a to
14d: piston, 15a to 15d: variable throttle valve,
16a to 16d: accumulators, 17, 18: gate valves, 21, 22, leveling valves, 24: hydraulic pumps, 25: reservoir tanks, 26: accumulators,
27: exhaust valve, 31: electric control unit, 32: vehicle speed sensor, 33: steering angle sensor, 34: pressure sensor, 35
a to 35d: vehicle height sensor; 36a to 36d: acceleration sensor.

Claims (3)

[Claims] 1. A plurality of hydraulic cylinders provided between a wheel and a vehicle body for each wheel position to attenuate vertical vibration of the vehicle body, and a pair of left and right wheel positions among the plurality of hydraulic cylinders are provided. A valve means provided in an oil passage communicating the hydraulic cylinders and capable of changing the degree of communication between the same pair of hydraulic cylinders; and detecting the turning traveling state of the vehicle to reduce the degree of communication of the valve means upon the detection. A first control means for controlling the side of the vehicle, wherein the occurrence of lateral roll of the vehicle body having a low frequency when traveling straight ahead of the vehicle is detected or estimated and the detection or estimation is performed at the time of the detection or estimation. A suspension device for a vehicle, further comprising second control means for controlling the degree of communication of the valve means to be smaller. 2. The second control means according to claim 1,
Based on the difference between the motion state amounts representing the vertical movement of the vehicle body at the left and right wheel positions when the vehicle travels straight, the occurrence of lateral roll of the vehicle body having a low frequency when the vehicle travels straight is detected. And a control device for controlling the valve means to reduce the degree of communication at the time of the detection. 3. The second control means according to claim 1,
On the condition that the vehicle speed in straight running of the vehicle is higher than or equal to a predetermined vehicle speed, the occurrence of lateral roll of the vehicle body having a low frequency during straight running of the vehicle is estimated. A suspension device for a vehicle, which controls the degree of communication of a valve means to be smaller.