JP3155376B2 - Vehicle suspension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular suspension control device for controlling a dive at the time of sudden braking of a vehicle.

[0002]

2. Description of the Related Art Generally, in a vehicle suspension,
A system that changes the damping force of the shock absorber and the gas spring constant of the air spring chamber to control the ride comfort and steering stability under any load condition, road surface condition or running condition of the occupant etc. is there.

[0003]

However, since the air spring chamber is generally installed above the shock absorber,
If the air spring chamber is made large in order to improve the ride comfort of the vehicle, the suspension unit becomes large.

The present invention has been made in view of the above circumstances, and provides a vehicle suspension control that can improve the ride comfort without increasing the size of the suspension unit and can control the vehicle dive satisfactorily. It is intended to provide a device.

[0005]

SUMMARY OF THE INVENTION A suspension control device for a vehicle according to the present invention includes a suspension unit installed on each wheel of a vehicle for independently suspending the wheels, and a shock absorber for each suspension unit.
The installed damping force adjustment mechanism and each suspension unit
High pressure gas filled high pressure gas in the shock absorber
Communicated with the accumulator and filled with low-pressure gas
By controlling the low pressure accumulator to communicate / cut off
Spring constant adjustment that allows the spring constant of the
Of the suspension unit before and after the vehicle
The shock absorbers are communicated with each other by the communication control valve.
A communication pipe connected so as to be able to be shut off , a vehicle speed sensor for detecting a vehicle speed, a brake switch for detecting the presence or absence of an operation of a brake, a vehicle speed from the vehicle speed sensor and the presence or absence of a brake operation from a brake switch; Calculate the deceleration from the vehicle speed, and based on these vehicle speeds, the presence or absence of the brake operation and the deceleration, open and close the communication control valve to control the communication pipe to the communication or cutoff state,
Using the damping force adjustment mechanism and the spring constant adjustment mechanism
Te in which and a control means for changing the damping force and spring constant of the suspension unit.

Further, the control means of the vehicle suspension control apparatus according to the present invention sets the communication pipe in a closed state and sets the damping force and the spring constant of the suspension unit to a higher value during the dive control. It is determined whether or not the steering angle detected by the angle sensor is equal to or larger than a reference value, and the continuation of the dive control and the stop after the holding time are selected and executed.

[0007]

The control means according to the present invention controls the suspension when the vehicle speed is equal to or higher than a predetermined value and a brake operation is input by a brake switch, and when the deceleration calculated from the vehicle speed is equal to or higher than a predetermined value. The damping force and the spring constant of the unit are set higher, and the communication control valve is closed to set the communication pipe in a cutoff state so that the suspension units before and after the vehicle are made independent. For this reason, each suspension unit is switched to the hard side as a whole, and the dive of the vehicle at the time of sudden braking can be favorably controlled.

Further, since the suspension units at the front and rear of the vehicle are connected by the communication pipe, the spring constant can be reduced (softened) without increasing the size of each suspension unit in the communication state, and the riding comfort of the vehicle is improved. Can be good.

Further, the control means stops the dive control after the holding time, especially when the steering angle is equal to or larger than the reference value during the dive control. Therefore, when the vehicle is turning around the intersection after the sudden braking, the dive control is maintained until the turning is completed, and the rolling of the turning vehicle can be prevented well.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a pipeline diagram showing one embodiment of a vehicle suspension control device according to the present invention, and FIG. 2 is a longitudinal sectional view showing a shock absorber in the suspension unit of FIG.

The suspension unit 1A shown in FIG.
1B, 1C, and 1D are respectively installed on four wheels of a vehicle, for example, a four-wheeled vehicle, and each wheel is independently buffered and suspended. Suspension units 1A and 1B are installed on each of the left and right front wheels, and suspension units 1C and
1D is installed on each of the left and right rear wheels. Each of the suspension units 1A, 1B, 1C and 1D includes a coil spring 2, a shock absorber 3 disposed in the coil spring, a high-pressure accumulator 5 connected to the shock absorber 3 via a hydraulic pipe 4, and a low-pressure accumulator 5. It has an accumulator 6, an accumulator control valve 7 and a relief valve 8 arranged in parallel with each other in the hydraulic pipe 4 on the low-pressure accumulator 6 side, and a damping force adjusting actuator 9 installed on the upper part of the shock absorber 3. Things. In addition, the code | symbol 10 in FIG. 1 shows a filter.

As shown in FIG. 2, the shock absorber 3 has a piston 13 housed inside a tube 11, thereby defining a lower oil chamber A and an upper oil chamber B. Further, a rod oil chamber D is formed in the piston rod 14 that enters and exits the tube 11. The piston rod 14 is connected to the vehicle body side, and the tube 11 is connected to the axle side.

The piston rod 14 and the tube 1
1, the upper and lower ends of the coil spring 2 shown in FIG. 1 are fixed, and the impact force acting on the wheels is absorbed. The metal spring constant of the coil spring 2 is always set to a constant value.

The rod oil chamber D of the shock absorber 3 shown in FIG. 2 is connected to the hydraulic pipe 4 (FIG. 1), and is connected to the oil chambers 15a and 16a of the high-pressure accumulator 5 and the low-pressure accumulator 6 through the hydraulic pipe 4. Communicated. The high-pressure accumulator 5 and the low-pressure accumulator 6 are partitioned into the oil chambers 15a and 16a and the gas chambers 15b and 16b by a free piston 17 housed slidably. A high-pressure gas is stored in the gas chamber 15b.
Low-pressure gas is sealed in b. Therefore, the gas spring constants of the suspension units 1A, 1B, 1C and 1D are set by the high-pressure gas 3 and the low-pressure gas. Suspension units 1A, 1B, 1C and 1
The spring constant of D is the sum of the metal spring constant and the gas spring constant.

The accumulator control valve 7 is normally open,
A solenoid valve that is closed when energized. When the accumulator control valve 7 is closed, the communication between the rod oil chamber D of the shock absorber 3 and the oil chamber 16A of the low-pressure accumulator 6 is interrupted, and the rod oil chamber D is communicated only with the oil chamber 15a of the high-pressure accumulator 5 to form the suspension unit 1A. , 1B, 1
The gas spring constants of C and 1D are increased, and the spring constants of these suspension units are set to be high (hard). On the contrary, when the accumulator control valve 7 is opened, the gas spring constants of the suspension units 1A, 1B, 1C, and 1D decrease, and the suspension units 1A, 1B, 1C, and 1D decrease.
The spring constants of A, 1B, 1C, and 1D are set low (soft). The relief valve 8 communicates with the low-pressure accumulator to protect the pipe system when the operating oil pressure in the hydraulic pipe 4 becomes equal to or higher than a predetermined value.

The piston 13 of the shock absorber 3 shown in FIG. 2 is provided with a piston valve 18, which slides inside the tube 11. When the piston rod 14 enters the contraction side of the shock absorber 3, the hydraulic oil flows from the lower oil chamber A to the upper oil chamber B via the piston valve 18, and the flow path resistance at this time generates a contraction-side damping force. At the same time, excess oil corresponding to the volume of the piston rod 14 that has entered is released to the accumulators 5 and 6 via the rod oil chamber D. When the shock absorber 3 is operated on the extension side, hydraulic oil flows from the upper oil chamber B to the lower oil chamber A via the piston valve 18, and at this time, an extension-side damping force is generated.

A rotary valve 20 is provided at the lower end of the piston rod 14 for communicating and blocking between the lower oil chamber A and the upper oil chamber B. The rotary valve 20 is connected to the damping force adjusting actuator 9 via a control rod 20A that passes through the rod oil chamber D of the piston rod 14. By the operation of the damping force adjusting actuator 9, the rotary valve 20 is switched between three stages of full opening, half opening and full closing. When the rotary valve 20 is fully opened, the hydraulic oil flows smoothly between the lower oil chamber A and the upper oil chamber B as the shock absorber 3 expands and contracts.
The damping force of the shock absorber 3 is set low (soft). Further, when the rotary valve 20 is fully closed, no hydraulic oil flows between the lower oil chamber A and the upper oil chamber B via the rotary valve 20, so that the damping force of the shock absorber 3 is set high (hard). When the rotary valve 20 is half-open, the damping force of the shock absorber 3 is set to medium.

As shown in FIG. 1, the hydraulic piping 4 of the suspension units 1A and 1C is connected to a high-pressure accumulator 5
In addition, a communication pipe 21 is connected between the accumulator control valve 7 and the shock absorber 3, and communication control valves 23A and 23C are provided in the communication pipe 21. The hydraulic piping 4 of the suspension units 1B and 1D
Are similarly connected by a communication pipe 22, and communication control valves 23B and 23D are provided in the communication pipe 22. These communication control valves 23A and 23C and 23B and 23D are normally closed solenoid valves which are open when energized.
The suspension units 1A and 1C operate independently when the communication control valves 23A and 23C are closed, and when the communication control valves 23A and 23C are opened, the communication pipes 4 of both suspension units are in a communication state. The suspension units 1B and 1D operate independently when the communication control valves 23B and 23D are closed, and the hydraulic pipes 4 of both suspension units are in communication when the communication control valves 23B and 23D are opened.

The communication of the hydraulic piping 4 of the suspension units 1A and 1C allows the suspension units 1A and 1C to communicate with each other.
The high-pressure accumulator 5 and the low-pressure accumulator 6 and the high-pressure accumulator 5 and the low-pressure accumulator 6 of the suspension unit 1C are in communication with each other. Become. Similarly, the communication of the hydraulic piping 4 of the suspension units 1B and 1D also causes the suspension unit 1
The spring constants of B and 1D are low (soft).

On the other hand, when the communication control valves 23A and 23C are closed and the suspension units 1A and 1C become independent, the suspension units 1A and 1C
Since the high-pressure accumulator 5 and the low-pressure accumulator 6 are separated from each other, the spring constant is increased (hardened) by that amount, and pitching that occurs when the load difference between the front and rear of the vehicle is large is suppressed. Similarly, the communication control valves 23B and 23D close and the suspension units 1B and 1D
Are independent, the suspension units 1B and 1
The spring constant of D is increased (hardened) to suppress pitching.

Further, as shown in FIG. 1, between the communication control valves 23A and 23C of the communication pipe 21 and between the communication control valves 23B and 23D of the communication pipe 22, a supply / discharge pipe of the hydraulic oil supply / discharge unit 24 is provided. 25 are connected. The hydraulic oil supply / discharge unit 24 has an oil supply pump 26 and a drain valve 27,
The drain valve 27 is a normally closed solenoid valve which is open when energized. Oil pump 26 when drain valve 27 is closed
, The hydraulic oil from the tank 28 is removed from the filter 29.
Through the check valve 30 and the supply / discharge pipe 25 to the communication pipes 21 and 22. These communication pipes 21
And 22 are supplied to the communication control valve 23A,
When the opening operation of 23B, 23C and 23D is performed, the suspension unit reaches the rod oil chamber D (FIG. 2) of the shock absorber 3 in the suspension units 1A, 1B, 1C and 1D, and reaches the lower oil chamber A when the rotary valve is opened. 1A, 1B, 1C and 1D are extended, and the vehicle height is set high.

When the drain valve 27 shown in FIG. 1 is opened, the suspension units 1A, 1B, 1C and 1D
The hydraulic oil in the lower oil chamber A of FIG.
0, through the rod oil chamber D and the hydraulic pipe 4, and from the communication pipes 21 and 22 shown in FIG. As a result, the suspension units 1A, 1B, 1C and 1D shrink, and the vehicle height is set low.

The above suspension units 1A, 1
Accumulator control valve 7 and damping force adjustment actuator 9 in B, 1C and 1D, communication control valve 23
A, 23B, 23C and 23D, the oil supply pump 26 and the drain valve 27 of the hydraulic oil supply / discharge unit 24 are controlled by a control circuit 32 as control means shown in FIG. The control circuit 32 receives detection signals from a vehicle speed sensor 33, a vehicle height sensor 34, a steering angle sensor 35, a brake switch 36, a throttle sensor 37, an ignition switch 38, and a door switch 39 installed at various parts of the vehicle. The control valve 7 for accumulator, the actuator 9 for adjusting damping force, and the communication control valves 23A to 23A
3D controls the refueling pump 26 and the drain valve 27.

The vehicle speed sensor 33 detects the vehicle speed, and the control circuit 32 calculates the acceleration / deceleration by differentiating the vehicle speed detected by the vehicle speed sensor 33. The vehicle height sensor 34 is installed in each of the suspension units 1A to 1D, and detects the amount of expansion and contraction movement of the shock absorber 3 in each of the suspension units 1A to 1D, that is, a suspension stroke (hereinafter, abbreviated as a suspension stroke). . Further, the steering angle sensor 35 detects the rotation angle of the steering wheel of the vehicle as the steering angle. Further, the brake switch 36 is turned off when the brake is actuated (stepping on).
An N signal is output and an OFF signal is output when the brake is not operated.

The throttle sensor 37 detects the opening of the throttle. The control circuit 32 calculates the throttle opening speed based on the detection value from the throttle sensor 37. In addition, the ignition switch 38
An ON signal is output when the vehicle engine is operated by an ON operation, and an OFF signal is output when the vehicle is turned OFF. Further, the door switch 39 outputs an ON signal when the vehicle door is closed, and outputs an OFF signal when the vehicle door is opened.

The control circuit 32, as shown in FIG.
When it is determined that the engine is operated by the ignition switch 38 and the door is closed by the door switch 39, the front-rear relation of the vehicle is determined, and the front-rear relation processing described later is performed. Thereafter, during traveling of the vehicle, the control circuit 32 performs a later-described high-speed traveling process when it is determined that the vehicle is in a high-speed state, and performs a later-described rough road traveling process when it is determined that the vehicle is traveling on a rough road. I do. In addition, when the roll, dive, and squat are determined during running of the vehicle, the posture control process is performed in the order of roll, dive, and squat as described later. Further, when the control circuit 32 is not performing the above-described attitude control process or the above-described rough road running process while the vehicle is running,
A vehicle height adjustment process described below for optimally adjusting the vehicle height is performed.
If the attitude control process or the rough road running process is performed during the vehicle height adjusting process, the vehicle height adjusting process is stopped, and the attitude control process or the rough road running process is prioritized.

The control circuit 3 will now be described with reference to FIGS.
The above two processes will be described individually.

(1) First, the pre- and post-related processing will be described with reference to FIG. The control circuit 32 includes the ignition switch 3
At 8, it is determined that the engine is operating, and after the door switch 39 determines that the door has been opened to closed, the vehicle speed is determined based on a signal from the vehicle speed sensor 33. Control circuit 3
2, when the vehicle speed is zero, it is determined that the vehicle is in a state immediately before starting, and the suspension height from the vehicle height sensor 34 is used to determine the vehicle height difference before and after the vehicle. The determination of the vehicle height difference is performed by the left and right suspension units 1A and 1 on the front wheel side.
The determination is made based on whether or not the difference between the average value of the suspension stroke of B and the average value of the suspension strokes of the left and right suspension units 1C and 1D on the rear wheel side is equal to or larger than a threshold value (for example, 30 mm).

When the difference is equal to or larger than the threshold value, for example, when three or more persons are on the rear seats of the vehicle and a total of five or more persons are on the vehicle, the load distribution before and after the vehicle is poor. Pitching is likely to occur during running of the vehicle. Therefore, the control circuit 32 closes the communication control valves 23A and 23C and 23B and 23D when the difference between the front wheel side and the rear wheel side suspension stroke averages is equal to or greater than the threshold value, and the communication circuit Cut off the communication between 21 and 22;
The suspension units 1A, 1B, 1C and 1D are made independent. As a result, each suspension unit 1A,
The high-pressure accumulator 5 and the low-pressure accumulator 6 of 1B, 1C, and 1D become independent from each other, and the spring constants of these suspension units 1A to 1D are increased, so that pitching of the vehicle can be suppressed.

When the difference between the average values of the front and rear suspension strokes is equal to or smaller than the threshold value, the control circuit 32 determines that pitching does not occur during running of the vehicle, and the communication solenoid valve is controlled. 23A and 23C and 23B and 23D are excited to open the suspension unit 1
The hydraulic pipes 4 of A and 1C are communicated by a communication pipe 21, and the hydraulic pipes 4 of the suspension units 1B and 1D are communicated by a communication pipe 22. Due to this communication, the suspension units 1A and 1C have a low spring constant and become soft due to the accumulators 5 and 6 of each other, and the suspension units 1B and 1D
Similarly, the spring constants are low and soft, and the accumulators 5 and 6 of each of the suspension units 1A to 1D are softened.
The ride comfort of the vehicle can be improved without increasing the size of the vehicle.

The front-rear related processing is not executed when the vehicle is running at a vehicle speed other than zero, and is not executed until the door is opened and then closed once executed. Further, when the engine is stopped, the control of the control circuit 32 is canceled, the communication solenoid valves 23A to 23D are closed, the suspension units 1A and 1C become unrelated, and the suspension units 1B and 1D become unrelated. .

It should be noted that the reason why the average value of the suspension stroke of the suspension units 1A and 1B was compared with the average value of the suspension stroke of the suspension units 1B and 1D in the front-rear related processing is that the vehicle was parked on the roadside.
Left and right suspension units 1A and 1B, 1C
This is because it is assumed that the suspension stroke may be biased in 1D and 1D.

(2) Next, the high-speed running process will be described with reference to FIG. The control circuit 32 controls the vehicle speed sensor 3 while the vehicle is running.
According to 3, when the vehicle speed exceeds a threshold value (for example, 100 km / h) for a time T ₁ (for example, 20 seconds) or more, it is determined that the vehicle is in a high-speed running state, and the suspension units 1A, 1B, and 1C are determined. And 1D accumulator control valve 7
Is operated to drive the damping force adjusting actuator 9 to switch the rotary valve 20 (FIG. 2) to the half-open state. By opening the control valve 7 for the accumulator, the suspension units 1A to 1D have their respective gas spring constants reduced, and their respective spring constants are reduced as a whole to be soft. Further, by the half-opening operation of the rotary valve 20 by the damping force adjusting actuator 9, the damping force of each of the shock absorbers 3 in the suspension units 1A to 1D is set to medium. As a result, it is possible to provide the vehicle with riding comfort and steering stability suitable for high-speed running.

Thereafter, when the vehicle speed detected by the vehicle speed sensor 33 is equal to or lower than a threshold value (for example, 80 km / h), the time T ₂
When more than (for example, 4 seconds) have elapsed, the control circuit 32
After the holding time, the high-speed running process is stopped. This suspension causes the damping force adjusting actuator 9 to rotate the rotary valve 2.
0 is switched to fully open, and the suspension units 1A-
The damping force of the 1D shock absorber 3 changes to soft, and the accumulator control valves 7 of the suspension units 1A to 1D are kept open to maintain the soft state. As a result, the vehicle is provided with a riding comfort and a steering stability suitable for medium-to-low speed traveling.

When the vehicle speed is equal to or lower than the threshold value in the above-described high-speed running process, the control circuit 32 determines that the vehicle is running at a low speed and outputs the suspension units 1A to 1A.
Keep the damping force and spring constant at D soft.
In the above-described high-speed running process and the later-described rough road running process and attitude control process, the control circuit 32 performs the switching of the damping force and the switching of the spring constant of the suspension units 1A to 1D for all the suspension units 1A to 1D. Are carried out simultaneously.

(3) Next, the rough road traveling processing will be described with reference to FIG. The control circuit 32, as shown in FIG.
If the vehicle speed detected by the vehicle speed sensor 33 is equal to or higher than a threshold value (for example, 40 km / h), the suspension stroke from the vehicle height sensor 34 installed in the front wheel side suspension units 1A and 1D is used as it is, Carry out the running process. This suspension stroke is indicated by a solid line in FIG. The control circuit 32 uses the suspension strokes detected by the vehicle height sensors 33 of the suspension units 1A and 1B as they are, and determines the difference between the fluctuation widths of the high and low peaks of the suspension stroke in a predetermined cycle (for example, one cycle). Within 3 cycles of 10 ms, the threshold value (for example, 30
mm), it is determined that the vehicle is traveling on a rough road, the accumulator control valves 7 of the suspension units 1A to 1D are opened, and the damping force adjusting accumulators 9 of the suspension units 1A to 1D are opened. To switch the rotary valve 20 (FIG. 2) to the half-open state. Each of the suspension units 1A to 1D has a low spring constant and softness due to the opening operation of the accumulator control valve 7, and has a medium damping force due to the half-opening operation of the rotary valve 20. Become.

If the difference between the fluctuation widths of the high and low suspension strokes does not exceed the threshold value for the predetermined period, the control circuit 32 determines that the vehicle is not traveling on a rough road. While the spring constant of the control valve 7 for the accumulator in each of the suspension units 1A to 1D is kept soft, the rotary valve 20 of each shock absorber 3 is switched to the fully open state to make the damping force of the shock absorber 3 low and soft. In this way, the suspension units 1A to 1D are set to characteristics suitable for traveling other than when traveling on a rough road.

The above-described change in the characteristics of the suspension units 1A to 1D during rough road running is performed using the suspension stroke detected by the vehicle height sensor 34 of the suspension units 1A and 1B on the front wheel side as it is.
Control is performed quickly.

In the rough road running process, when the vehicle speed is equal to or lower than the threshold value, it is not necessary to change the characteristics of the suspension units 1A to 1D even if the vehicle is actually running on a rough road. Keeps the spring constants and damping forces of these suspension units 1A to 1D soft.

(4) Next, with reference to FIG. 8 to FIG. 10, a description will be given of a vehicle attitude control process in a roll, dive, and squat. This attitude control process is performed both during the high-speed running and on the rough road, and improves the steering stability particularly during the high-speed running and on the rough road.

(4-1) Roll Control As shown in FIGS. 8B and 8C, the control circuit 32 has an ON map indicating the relationship between the vehicle speed and the steering angle and an OFF map.
A map is stored in advance. The ON map sets a steering angle at which a predetermined value of lateral acceleration is predicted to act on the vehicle for each vehicle speed, and is indicated by a solid line in FIG. 8C.
The area of the steering angle equal to or larger than the steering angle described in the ON map for each vehicle speed is the ON area. At the steering angle in the ON region, a lateral acceleration equal to or greater than the predetermined value acts on the vehicle, and the vehicle rolls.

The OFF map is a map in which a steering angle at which a constant lateral acceleration (a lateral acceleration smaller than the predetermined value) is expected to act on the vehicle is set for each vehicle. Shown by solid lines. This OFF map is ON
Set with map and hysteresis. For each vehicle speed, the region of the steering angle equal to or less than the steering angle described in the OFF map is the OFF region. At the steering angle within this OFF region, the lateral acceleration equal to or less than the above-mentioned constant value acts on the vehicle, and the rolling of the vehicle rolls. Low enough to not require control.

The control circuit 32 first determines whether or not the vehicle speed detected by the vehicle speed sensor 33 and the steering angle detected by the steering angle sensor 35 are in the above-described ON region.
When it is determined that the vehicle is in the N region, it is determined that rolling occurs in the vehicle, and the characteristics of the suspension units 1A to 1D are changed in the following three cases. The three cases are a case where the vehicle is not traveling at high speed and is not traveling on a rough road, a case where the vehicle is traveling at high speed, and a case where the vehicle is traveling on a rough road.

In any of these cases, the damping force adjusting actuators 9 of the suspension units 1A to 1D are driven to fully close the rotary valve 20, and the damping force of the shock absorber 3 of each of the suspension units 1A to 1D is switched to hardware. . Furthermore, the communication control valves 23A-
23D is closed to cut off the communication between the suspension units 1A and 1C and, at the same time, also cut off the communication between the suspension units 1B and 1D.
〜1D operate independently. Suspension unit 1
Regarding the spring constants of A to 1D, the accumulator control valve 7 is opened to drive the high-pressure accumulator 5 and the low-pressure accumulator 6 to communicate with the hydraulic pipe 4 when the vehicle is traveling on a rough road, and the spring constant is maintained soft. In the other two cases, the accumulator control valve 7 is closed, only the high-pressure accumulator 5 is communicated with the hydraulic pipe 4, and the spring constant is set to hard.

In any of the above cases, when the steering angle is in the ON range, the characteristics of the suspension units 1A to 1D are switched to the hard side as a whole, and the rolling control during the turning of the vehicle is favorably prevented. it can.

The control circuit 32 compares the detected steering angle with the OFF map for each vehicle speed after the start of the above control and the holding time has elapsed, and determines whether to continue or stop the control. That is, the control circuit 32 continues the roll control when the steering angle is out of the OFF region, and stops the roll control after the elapse of the holding time when the steering angle is in the OFF region.

With the suspension of the roll control, the damping force of the shock absorbers 3 of the suspension units 1A to 1D is returned to the medium when the vehicle is traveling at high speed and when traveling on a rough road. It is returned to soft when not running. Further, the spring constants of the suspension units 1A to 1D are returned to soft in any of the above three cases, and the communication control valves 23A to 23
4D is also returned to its original operating state of either open or closed.

(4-2) Dive control The control circuit 32 determines that the vehicle speed detected by the vehicle speed sensor 33 exceeds a predetermined threshold value (for example, 30 km / h), and that the brake is depressed. Brake switch 36
When the ON signal is output from the controller, the dive is predicted to occur in the vehicle, and the characteristics of the suspension units 1A to 1D are changed in three cases similar to the roll control in (4-1).

That is, the control circuit 32 controls the suspension unit when the vehicle is not traveling at high speed and on a rough road, when the vehicle is traveling at a high speed, and when the vehicle is traveling on a rough road. The damping force adjusting actuator 9 of 1A to 1D is driven to fully close the rotary valve 20, and the damping force of the shock absorber 3 is switched to hardware. Further, the communication control valves 23A to 23D are closed to interrupt the continuity of the suspension units 1A and 1C, and at the same time, the communication of the suspension units 1B and 1D is also interrupted to operate the suspension units 1A to 1D independently. Also, the suspension units 1A ~
Regarding the spring constant of 1D, the accumulator control valve 7 is opened and the high-pressure accumulator 5 and the low-pressure accumulator 6 are communicated with the hydraulic pipe 4 when the vehicle is traveling on a rough road to maintain the spring constant softly. In the two cases, the control valve 7 for the accumulator is closed so that only the high-pressure accumulator 5 communicates with the hydraulic pipe 4, and the spring constant is set to hard.

After changing the characteristics of the suspension units 1A to 1D to the hardware side and starting the dive control, the control circuit 32 performs the vehicle speed sensor 33 for a predetermined time.
The deceleration of the vehicle calculated based on the vehicle speed is compared with a threshold value (for example, 0.3 G) as a constant value. In other words, as shown in FIG. 9B, the control circuit 32 continues the dive control when the threshold value is continuously exceeded N times (three times) in each cycle during the predetermined time, and the control circuit 32 continues the dive control. When there is no dive control, the dive control after the holding time (for example, 1 second) is stopped in order to prevent the vehicle from rolling back due to the dive control.

When the dive control is stopped, the damping force of the shock absorbers 3 of the suspension units 1A to 1D is returned to the medium when the vehicle is traveling at a high speed and when traveling on a rough road. When the vehicle is not running on the road, it is returned to the software. Further, the spring constants of the suspension units 1A to 1D are returned to soft in all three cases, and the communication control valves 23A to 23D are controlled.
D is also returned to the original operating state of either opening or closing.

When the dive control is continued and the steering angle detected by the steering angle sensor 35 exceeds a threshold value (eg, 200 degrees) as a reference value, the control circuit 3
2, the dive control is suspended after the dive control is continued for a holding time (for example, 3 seconds). By continuing the dive control during the holding time, when the vehicle is turning at the intersection after the sudden braking, the dive control is continued until the turning is completed, and rolling is prevented.

During the dive control, the control circuit 32
Calculates the deceleration again from the vehicle speed and compares the deceleration with a threshold value (for example, 0.1 G). The control circuit 32 continues the dive control when the deceleration is equal to or more than the threshold value, and stops the dive control after the elapse of the holding time when the deceleration is equal to or less than the threshold value.

By the above-described dive control, the characteristics of the suspension units 1A to 1D are changed when the vehicle is traveling at a high speed, when traveling on a rough road, and when the vehicle is not traveling at a high speed and traveling on a rough road. As a whole, the dive becomes hard, and the dive in which the front wheel side shrinks and the rear wheel side floats up during sudden braking can be favorably controlled.

The suspension units 1A to 1D
When the steering angle becomes large during dive control with the characteristics of the whole as hard, the dive control was continued only for the holding time, so when cornering after sudden braking, rolling of the vehicle was suppressed until cornering was completed. it can.

(4-3) Squat Control The control circuit 32 determines that the vehicle speed detected by the vehicle speed sensor 33 is equal to or higher than a threshold value (for example, 20 km / h), and the throttle opening detected by the throttle sensor 37 is When the throttle opening speed is equal to or more than the threshold value (for example, 4 / 8θth) and the throttle opening speed is also equal to or more than the threshold value (for example, 5 / 16θth in 30 ms), squat control is started by predicting that the vehicle will squat. I do. When the vehicle speed is equal to or lower than the threshold value, the squat control is not performed because the behavior of the vehicle due to the squat is small. Further, when the throttle opening and the throttle opening speed are equal to or less than the respective threshold values, the squat control is not necessary since the engine is in the idle state or at the time of low acceleration.

In the squat control, the characteristics of the suspension units 1A to 1D are changed in three cases similar to the roll control and the dive control. That is, the control circuit 32 controls the suspension units 1A to 1D regardless of whether the vehicle is traveling at high speed or on a rough road, the vehicle is traveling at a high speed, or the vehicle is traveling on a rough road. The damping force adjusting actuator 9 is driven to fully close the rotary valve 20, and the damping force of the shock absorber 3 is switched to hardware. Further, the communication control valves 23A to 23D are closed to cut off the communication between the suspension units 1A to 1D, and at the same time, the communication between the suspension units 1B and 1D is also cut off, so that the suspension units 1A to 1D are operated independently. Also,
Regarding the spring constants of the suspension units 1A to 1D, the control valve 7 for the accumulator is opened and the high-pressure accumulator 5 and the low-pressure accumulator 6 are communicated with the hydraulic pipe 4 when the vehicle is traveling on a rough road, and the spring constant is maintained soft. However, in the other two cases, the control valve 7 for the accumulator is closed so that only the high-pressure accumulator 5 communicates with the hydraulic pipe 4, and the spring constant is set to hard.

After the control circuit 32 starts the squat control by changing the characteristics of the suspension units 1A to 1D in this way, after a predetermined time has passed, the vehicle speed sensor 33
The squat control is determined to be continued or stopped using the vehicle speed and the throttle opening from the throttle sensor 37. That is, the control circuit 32 determines whether the vehicle speed after the lapse of the predetermined time is equal to or less than a threshold value (for example, 80 km / h) or the throttle opening after the lapse of the predetermined time is equal to the threshold value (3 / 8θth). In any of the following cases, the squat control is stopped after the elapse of the holding time.

The holding time is set in order to reduce the behavior of the vehicle due to the extreme opening and closing of the throttle. The vehicle speed threshold value is a vehicle speed at which acceleration is no longer required. Further, the threshold value of the throttle opening is
The opening is such that sudden acceleration does not occur in the vehicle.

When the squat control is stopped, the damping force of the shock absorbers 3 of the suspension units 1A to 1D is returned to the medium when the vehicle is traveling at high speed and when traveling on a rough road. If not, it is returned to the software. Furthermore, the spring constants of the suspension units 1A to 1D are returned to soft in any of the above three cases, and the communication control valve 23A
To 23D are returned to the original operating state of either open or closed.

(5) Finally, the vehicle height adjustment processing will be described with reference to FIGS. As shown in FIG. 11, the control circuit 32 first inputs a suspension stroke as vehicle height data from a vehicle height sensor 34 installed in each of the suspension units 1A to 1D, and calculates the value of the suspension stroke for each continuous minute time. For example, seven pieces are taken out and averaged, and further adjacent five pieces of average data are taken out and averaged to calculate moving average vehicle height data. Height sensor 34
If the suspension stroke detected from is used as the vehicle height adjustment data as it is, the frequency of the data is too high to determine the vehicle height, so that the moving average processing is performed as described above. This moving average vehicle height data is shown by the solid line in FIG. If the moving average vehicle height data exceeds the upper and lower threshold values only within the monitoring time T ₁ second (for example, 100 msec), the control circuit 32 determines that the moving average vehicle height exceeds the threshold value. Delete the data as indicating vibration due to sudden impact.

Next, the control circuit 32, while the moving average vehicle height data is not less than the T ₁ second (e.g., 100m seconds), determines whether it exceeds the upper threshold or below the threshold, exceeds If not, the vehicle height is determined to be optimal and vehicle height adjustment is not performed. Further, when the upper or lower threshold is exceeded the above T _1, the monitoring time on the threshold or the lower threshold moving average vehicle height data from beyond the T ₁ seconds T
_If the vehicle continues to exceed the upper threshold value or the lower threshold value for more than ₂ seconds (for example, 10 seconds), it is determined that vehicle adjustment is necessary, and the vehicle height is increased (UP) or the vehicle height is decreased (DOW).
N).

That is, when the moving average vehicle height data is equal to or higher than the upper threshold value, the control circuit 32 opens the drain valve 27 shown in FIG. 1 and also opens the communication control valves 23A to 23D. The hydraulic oil from the lower oil chamber A (FIG. 2) in the shock absorbers 3 of the suspension units 1A to 1D is discharged to the tank 28 (FIG. 1) to contract the shock absorbers 3 and lower the vehicle height (DOWN). Let it. When the moving average vehicle height data is equal to or lower than the lower threshold value, the control circuit 32 activates the oil supply pump 26 of FIG. 1 to open the communication control valves 23A to 23D, thereby causing the hydraulic oil in the tank 28 to open. The suspension units 1A-1
Lower oil chamber A in D shock absorber 3 (FIG. 2)
The shock absorber 3 is extended by inward, and the vehicle height is increased (UP).

Next, as shown in FIG.
Means that the moving average vehicle height data during vehicle height processing is T ₁ second (100m
When the vehicle is within the upper and lower thresholds for more than (seconds), the vehicle height processing is stopped. The control circuit 32, the monitoring time T ₂ extend two seconds each time performing the vehicle height adjustment once, reducing the frequency of the vehicle height adjustment. Monitoring time T ₂ are, does not exceed the maximum 60 seconds. During this extended monitoring time T ₂ , the door is opened and the OFF signal is output from the door switch 39 to the control circuit 32.
Or when the engine is stopped and an OFF signal is input from the ignition switch 38, the operation is reset to the original value (10 seconds).

As shown in FIG. 12, when the engine is stopped and the OFF signal is input from the ignition switch 38, the control circuit 32 turns on the built-in timer.
N operation is performed. When the door is closed and the ON signal is input from the door switch 39 within the time T ₃ (for example, 60 seconds; a maximum of 3 minutes) counted by the timer, the control circuit 32 performs the vehicle height adjustment processing as described above. It is performed to stop the vehicle height adjustment processing when not close is T ₃ hours or more doors.
The vehicle height adjustment processing, for example, is carried out after an entry and exit of people into T ₃ hours after stopping the engine.

Incidentally, the control of the vehicle height adjustment processing described in the item (5) differs depending on whether or not there is the front-rear related processing. That is, when the communication control valves 23A to 23D are opened to communicate the front and rear left suspension units 1A and 1C with the front and rear right suspension units 1B and 1D, the control circuit 32 controls the front wheel suspension. The suspension strokes of the units 1A and 1B are used as the vehicle height data, and the vehicle height adjustment is performed by giving priority to the decrease in the vehicle height (DOWN).

When the communication control valves 23A to 23D are closed, the front and rear left and right suspension units 1A and 1D are closed.
C, the front and rear right suspension units 1B and 1D are both in non-communication state,
When A to 1D are independent, the suspension strokes of the suspension units 1A, 1B, 1C and 1D are used as vehicle height data, and the vehicle height adjustment process gives priority to the front wheel side suspension units 1A and 1B, and Priority is given to a decrease in vehicle height (DOWN).

As described above, in this vehicle height adjustment processing, the moving average vehicle height data obtained by performing the moving average processing is used without using the suspension strokes of the suspension units 1A to 1D. Height data is T
Having adjusted the height only when continuously for _one second and T ₂ seconds exceeds the threshold value, the vehicle height does not change by sudden impact. Therefore, it is possible to realize the vehicle height adjustment suitable for the driver's feeling.

[0069]

As described above, in the vehicle suspension control device according to the present invention, the suspension units installed on the front and rear wheels of the vehicle are communicably connected by the communication pipes. The ride comfort can be improved without inducing. In addition, since the control means controls the communication pipe to open or close by opening and closing the vehicle control valve based on the vehicle speed, the presence or absence of the brake operation, and the deceleration, and changes the damping force and the spring constant of the suspension unit. Thus, the dive can be satisfactorily controlled when the vehicle is suddenly braked. Further, the control means determines whether or not the steering angle detected by the vehicle speed sensor during the dive control is equal to or larger than the reference value, and selects and executes the continuation of the dive control and the stop after the holding time, so that While turning at the intersection after braking, the dive control is maintained until the turning is completed, and the rolling at the time of turning can be controlled.

[Brief description of the drawings]

FIG. 1 is a pipeline diagram showing one embodiment of a vehicle suspension control device according to the present invention.

FIG. 2 is a longitudinal sectional view showing a shock absorber in the suspension unit of FIG. 1;

FIG. 3 is a block diagram showing a control system of each device in FIG. 1;

FIG. 4 is a flowchart showing the entire control performed by the control circuit of FIG. 3;

FIG. 5 is a flowchart of pre- and post-related processing performed by the control circuit of FIG. 3;

FIG. 6 is a flowchart of a high-speed running process performed by the control circuit of FIG. 3;

7A is a flowchart of a rough road traveling process performed by the control circuit of FIG. 3, and FIG. 7B is a graph showing a relationship between a front suspension stroke and a threshold.

8A is a flowchart of a roll control process performed by the control circuit of FIG. 3, FIG. 8B is a chart showing an ON map and an OFF map, and FIG. 8C is a chart showing an ON area and an OFF area; It is a graph.

9A is a flowchart showing a dive control process performed by the control circuit of FIG. 3, and FIG. 9B is a graph showing deceleration.

FIG. 10 is a flowchart showing squat control processing performed by the control circuit of FIG. 3;

FIG. 11 is a flowchart showing the first half of a vehicle height adjustment process performed by the control circuit of FIG. 3;

FIG. 12 is a flowchart showing the latter half of the vehicle height adjustment processing performed by the control circuit of FIG. 3;

FIG. 13 is a graph showing a relationship between moving average vehicle height data and a threshold value.

[Explanation of symbols]

 1A, 1B, 1C, 1D Suspension unit 3 Shock absorber 5 High-pressure accumulator 6 Low-pressure accumulator 7 Control valve for accumulator 9 Actuator for adjusting damping force 20 Rotary valve 21, 22 Communication pipe 23A, 23B, 23C, 23D Communication control valve 24 Operation Oil supply / discharge unit 26 Oil supply pump 27 Drain valve 32 Control circuit 33 Vehicle speed sensor 34 Vehicle height sensor 35 Steering angle sensor 36 Brake switch 37 Throttle sensor 38 Ignition switch 39 Door switch

Continued on the front page (72) Inventor Toshiyuki Takagusagi 1-14-1, Fujiwara-cho, Gyoda-shi, Saitama Prefecture Showa Manufacturing Co., Ltd. Saitama headquarters plant (72) Inventor Nobuo Mori 1-14-1 Fujiwara-cho, Gyoda-shi, Saitama No. 1 Showa Manufacturing Co., Ltd. Saitama Head Office Factory (72) Inventor Tetsuya Shiroya 1-14-1 Fujiwara-cho, Gyoda City, Saitama Prefecture Showa Manufacturing Co., Ltd. Saitama Head Office Factory (56) References JP 63-49508 ( JP, A) Japanese Utility Model Showa 64-45508 (JP, U) Japanese Utility Model Showa 64-42910 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60G 17/015 B60G 21/10

Claims (2)

(57) [Claims] 1. A installed in each wheel of the vehicle and a suspension unit for buffering suspended independently each wheel, each suspension
Installed in the shock absorber of the pension unit
The damping force adjustment mechanism and the suspension unit
High-pressure accumulator with high-pressure gas sealed in the shock absorber
And a low-pressure accumulator filled with low-pressure gas.
The suspension unit is controlled by controlling the
Spring constant adjustment mechanism that can change the spring constant of the unit
And the shock of the above suspension unit before and after the vehicle
The absorber can be connected / disconnected with each other by the control valve for communication
A communication pipe connected to the vehicle, a vehicle speed sensor for detecting a vehicle speed,
A brake switch for detecting the presence or absence of a brake operation;
The vehicle speed from the vehicle speed sensor and the presence / absence of a brake operation from a brake switch are determined, and the deceleration is calculated from the vehicle speed. Based on the vehicle speed, the presence / absence of the brake operation and the deceleration, the control valve for communication is opened / closed. and controls the communication or blocked state the communication piping, the damping
A suspension control device for a vehicle, comprising: a force adjusting mechanism; and control means for changing a damping force and a spring constant of the suspension unit using the spring constant adjusting mechanism . 2. The vehicle suspension control device according to claim 1, further comprising a steering angle sensor for detecting a steering angle, wherein the control unit sets the communication pipe to a cutoff state, and sets a high damping force and a high spring constant of the suspension unit. And determining whether the steering angle detected by the steering angle sensor is equal to or larger than a reference value during execution of the dive control, and selecting and executing continuation of the dive control and suspension after a holding time. A suspension control device for a vehicle according to claim 1.