JPH078247Y2 - Vehicle height adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a vehicle height adjusting device used for vehicle attitude control and the like.

(Prior Art) Conventionally, as a vehicle height adjusting device, for example, Japanese Patent Laid-Open No. 62-9612
There is known one used in a vehicle height adjustment type roll control device described in Japanese Patent No.

This conventional device is connected to an accumulator that temporarily stores the hydraulic pressure supplied from an engine-driven pump, and is connected to the accumulator via a hydraulic pressure supply circuit. The output hydraulic pressure is adjusted by adjusting the drain amount to the drain circuit side. And a vehicle height adjustment actuator that is driven by the output hydraulic pressure of the pressure control valve and that can change the vehicle height. It was possible to control the posture of the vehicle by, for example, to keep the posture of the vehicle horizontal even when acceleration in the roll direction occurs.

(Problems to be solved by the invention) However, in such a conventional device, when the engine is stopped, the hydraulic pressure accumulated in the accumulator is gradually released to the downstream side, that is, the actuator side. Therefore, there was a problem that the vehicle height would rise after the engine was stopped.

Further, in the case where the check valve is not provided on the drain circuit side of the pressure control valve, there is a problem that the hydraulic pressure leaks from the pressure control valve and the vehicle height decreases after the engine is stopped.

(Means for Solving Problems) The present invention aims to provide a vehicle height adjusting device which does not change the vehicle height after the engine is stopped. In order to achieve this invention,
The following solutions were adopted.

That is, an accumulator that temporarily stores the hydraulic pressure supplied from an engine-driven pump and a pressure control that is connected to the accumulator via a hydraulic pressure supply circuit and is also connected to the drain circuit side to control the output hydraulic pressure. Valve, a vehicle height adjusting actuator driven by the output hydraulic pressure of the pressure control valve and capable of controlling the vehicle height and attitude, and a backflow to the accumulator side provided between the accumulator and the pressure control valve of the hydraulic pressure supply circuit. And a first check valve for preventing the above, and a pressure control valve side which is provided in the drain circuit and opens when a hydraulic pressure is generated in the hydraulic pressure supply circuit closer to the accumulator than the first check valve and is closed when a non-hydraulic pressure is generated. The second check valve for preventing backflow to the hydraulic circuit and a hydraulic pressure relief circuit connecting the hydraulic pressure supply circuit and the drain tank at a position closer to the accumulator than the first check valve, the hydraulic pressure relief circuit is opened and closed. And unloading valve provided in ability to drain the circuit of the position between the pressure control and the second check valve,
A cut valve that can open and close this drain circuit, and when the engine is driven, the unload valve is closed and the cut valve is opened, and when the engine is stopped, the unload valve is opened. An open / close control circuit for closing the cut valve for at least a predetermined time.

(Operation) The operation of the vehicle height adjusting device of the present invention will be described.

(A) When the engine is driven When the pump is driven by the engine, the generated hydraulic pressure is accumulated in the accumulator and is supplied to the pressure control valve through the hydraulic circuit including the first check valve.

At this time, the opening / closing control circuit closes the unload valve and the cut valve to prevent the hydraulic pressure of the hydraulic pressure supply circuit from escaping from the hydraulic pressure relief circuit to the rank. , Draining from the pressure control valve is allowed, and thus the pressure control valve can be operated.

The pressure control valve is operated to adjust the vehicle height to the target vehicle height, the output hydraulic pressure is controlled, and the vehicle height adjusting actuator is driven based on the output hydraulic pressure to adjust the vehicle height to the target vehicle height.

Also, the hydraulic fluid drained by the pressure control valve opens via the drain circuit in conjunction with the cut valve that was opened when the engine was driven by the opening / closing control circuit and the hydraulic pressure supply circuit that generated hydraulic pressure. After passing through the second check valve which has become, it is discharged to the drain tank.

By adjusting the vehicle height in accordance with the change in the attitude of the vehicle body, it is possible to control the attitude of the vehicle.

(B) When the engine is stopped When the engine is stopped, the open / close control circuit controls the unload valve to be open and the cut valve to be closed.

As a result, the hydraulic pressure relief circuit is opened, the hydraulic pressure supply circuit upstream of the first check valve (accumulator side) is connected to the drain tank, and the hydraulic pressure stored in the accumulator and the hydraulic pressure in the hydraulic pressure supply circuit are accumulated. The hydraulic pressure is drained.

On the other hand, since the first check valve is provided, the hydraulic pressure downstream of this (on the side of the pressure control valve and the vehicle height adjusting actuator) does not flow back to this hydraulic pressure relief circuit side. Also,
As described above, until the hydraulic pressure in the hydraulic pressure supply circuit and the accumulator is drained below a predetermined value, the second check valve is opened by the hydraulic pressure in this hydraulic pressure supply circuit, but the engine is stopped. At the same time, the cut valve is closed by the opening / closing control circuit and the drain circuit is closed, so that the hydraulic pressure in the pressure control valve and the vehicle height adjusting actuator is not drained from the drain circuit.

Since the second check valve is closed when the hydraulic pressure upstream of the first check valve is drained, the cut valve may be opened in this state.

Therefore, in the vehicle height adjusting device of the present invention, when the engine is stopped, the hydraulic pressure on the accumulator side does not flow into the vehicle height adjusting actuator side, and the hydraulic pressure on the vehicle height adjusting actuator side is drained from the drain circuit. Without incident,
The vehicle height adjusting actuator holds the hydraulic pressure when the engine is stopped. Therefore, the vehicle height adjusting actuator does not drive to the vehicle height increasing side or the vehicle height decreasing side when the engine is stopped, and the vehicle height (vehicle attitude) when the engine is stopped is maintained.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In describing this embodiment, a bydro pneumatic suspension system installed in an automobile will be taken as an example.

First, the configuration will be described.

FIG. 1 is an overall view showing a hydropneumatic suspension system including a vehicle height adjusting device according to an embodiment of the present invention, in which 1 is driven by an engine 2 and a tank 3 is used.
A pump that sucks and discharges the hydraulic fluid from the pump is shown. The hydraulic pressure generated by the pump 1 is temporarily stored in the sub accumulator 4a and the main accumulator 4b.

The accumulators 4a, 4b are connected to a pressure control valve 6 via a hydraulic pressure supply circuit 5.

In the middle of the hydraulic pressure supply circuit 5, the pressure control valve 6
To prevent back flow of hydraulic fluid from the side of the accumulator 4b
A check valve 7 is provided.

The pressure control valve 6 is connected to the drain circuit 8 and the output circuit 9, and adjusts the flow rate of the hydraulic fluid to the output circuit 9 and the drain amount to the drain circuit 8 by the accumulator pressure from the hydraulic pressure supply circuit 5. This is a well-known valve having a valve body (not shown), a solenoid, and a spool, which is a valve for setting the output hydraulic pressure to the output circuit 9 to a predetermined control hydraulic pressure according to the control command current value ic from the controller 10. Detailed description is omitted.

A vehicle height adjusting actuator 11 is provided at the tip of the output circuit 9. The vehicle height adjusting actuator 11 is an actuator that is interposed between the body side 101 on the spring and the wheel side 102 on the unsprung side, and is operated by the output hydraulic pressure from the pressure control valve 6, and is a strut-shaped coil spring. 111 is coaxially arranged, and a gas chamber 118 forming a gas spring is provided on the output circuit 9 side.

The coil spring 111 is an auxiliary suspension spring and can be omitted if the output hydraulic pressure can be increased.

Then, the vehicle height adjusting actuator 11 includes a cylinder 112,
A piston 113 and a piston rod 114 are provided, and inside the cylinder 112 by the piston 113, a piston upper chamber 115 having a small pressure receiving area and a piston lower chamber 116 having a large pressure receiving area are provided.
When the output hydraulic pressure is supplied via the rod passage 117, the relative distance H between the vehicle body side 101 and the wheel side 102 (the higher the pressure is, the larger the pressure is) is determined according to the pressure level.

A communication passage may be provided in the piston 113 as in the embodiment, and the pressure receiving portion for adjusting the vehicle height may be the piston rod cross-section portion.

That is, the vehicle height adjusting actuator 11 is provided at each position of the four wheels of the vehicle body (not shown), and the vehicle height is controlled by adjusting the vehicle heights (relative distances H) at these four locations to control the posture of the vehicle. It is a thing.

Further, the controller 10 as an input means detects G generated in each of the front-back, left-right, and up-down directions of the vehicle body.
The sensor group 12 is provided, and the output hydraulic pressure to each attitude control actuator 11 is calculated based on a signal from the G sensor group 12 in order to bring the vehicle body attitude to a target state such as a horizontal state,
A control command signal to the pressure control valve 6 based on the calculation result.
It outputs ic.

The drain circuit 8 is a circuit from the pressure control valve 6 to the tank 3, and a second check valve 13 and a cut valve 14 are provided on the way.
Is provided.

The second check valve 13 is opened and closed by receiving the pilot pressure from the hydraulic pressure supply circuit 5 located between the accumulator 4b and the first check valve 7, and is opened when the pilot pressure is high. When the pilot pressure becomes close to the drain pressure, it closes and shuts off the drain circuit.

The cut valve 14 is an operation signal from the opening / closing control circuit 15.
This is a normally open valve that closes the solenoid 141 by driving s1 to close the drain circuit 8.

Further, in the figure, the hydraulic pressure relief circuit 16 is shown. The hydraulic pressure relief circuit 16 has one end connected to the hydraulic pressure supply circuit 5 located between the accumulators 4a and 4b, and the other end connected to the tank 3. An unload valve 17 is provided in the hydraulic pressure relief circuit 16.

The unload valve 17 is a normally open valve that is actuated by the solenoid 171 to be closed by inputting the operation signal s2 from the opening / closing control circuit 15 to close the hydraulic pressure relief circuit 16.

The opening / closing control circuit 15 is connected to an ignition switch 18, and based on ON / OFF of the ignition switch 18, that is, based on a driving state of the engine 2, an operation signal s1 is sent to the cut valve 14 and the unload valve 17. , s2 is output, and the ignition switch 18 is turned on.
At the time of (engine driving), the operation signal s2 is output to the unload valve 17 to close the valve, and when the ignition switch 18 is switched from ON to OFF, that is, when the engine 2 is stopped. From the operation signal s1 to the cut valve 14 for a fixed time T (see FIG. 3).
Is output to close the valve. The time T during which the operation signal s1 is output is the time until the second check valve 13 is closed after the pilot pressure of the second check valve 13 is reduced after the driving of the engine 2 and the pump 1 is stopped. It is set longer.

Next, the operation of the embodiment will be described with reference to the time charts of FIGS. 2 and 3.

As shown in FIG. 2, when the ignition switch 18 is turned ON and the engine 2 is started (a), the pump 1 is driven by the engine 2 and the operation signal s2 for closing the unload valve 17 is output from the opening / closing control circuit 15. The hydraulic pressure relief circuit 16 is output to close (b), the hydraulic pressure in the hydraulic pressure supply circuit 5 rises (d), and this hydraulic pressure is stored in the accumulators 4a and 4b, and at this hydraulic pressure, 1 Check valve 7 is opened (c)
A hydraulic pressure is supplied to the pressure control valve 6 through the hydraulic pressure supply circuit 5.

The pressure control valve 6 is operated by the control command signal ic from the controller 10 to adjust the vehicle height (relative distance H) to the target vehicle height (g), and the output hydraulic pressure is controlled. The height adjustment actuator 11 is driven to adjust the vehicle height (relative distance H) to the target vehicle height.

In this state, in the drain circuit 8, the second check valve 13
Is opened by receiving the pilot pressure from the hydraulic pressure supply circuit 5 (e), and the cut valve 14 is kept in the normally open state, so the drain circuit 8 is opened (f) and the pressure control valve 6
The drain from is allowed.

Then, as shown in FIG. 3, the ignition switch
When the engine 2 is stopped by turning OFF 18 (a), the opening / closing control circuit 15 outputs the operation signals s1 and s2, and the unload valve 1
7 is opened (b), and the cut valve 14 is closed for a predetermined time T (f).

As a result, the hydraulic pressure relief circuit 16 opens, the hydraulic pressure supply circuit 5 upstream of the first check valve 7 communicates with the tank 3, and the hydraulic pressure and hydraulic pressure supply circuit accumulated in the accumulators 4a and 4b. The hydraulic pressure in 5 is drained.

On the other hand, the first check valve 7 is closed by the hydraulic pressure on the pressure control valve 6 and the vehicle height adjusting actuator 11 side (c), and the hydraulic pressure on the vehicle height adjusting actuator 11 side flows back to the hydraulic pressure relief circuit 16 side. There is no such thing. Further, as described above, the second check valve 13 is opened by the hydraulic pressure of the hydraulic pressure supply circuit 7 until the hydraulic pressures in the hydraulic pressure supply circuit 5 and the accumulators 4a, 4b decrease below a predetermined level. Although (d) and (e), the cut valve 14 is closed by the opening / closing control circuit 15 when the engine is stopped.
Since the drain circuit 8 is shut off, the hydraulic pressure in the pressure control valve 6 and the vehicle height adjusting actuator 11 is not drained from the drain circuit 8.

When the hydraulic pressure in the hydraulic pressure supply circuit 5 upstream of the first check valve 7 is drained, the second check valve 13 is closed (e), and then the operation signal from the opening / closing control circuit 15 is output. The output of s1 is stopped and the cut valve 14 is closed (f).

Therefore, in the hydropneumatic suspension of the embodiment, when the engine is stopped, the hydraulic pressure on the accumulator 4b side does not flow into the vehicle height adjusting actuator 11 side,
Further, the hydraulic pressure on the vehicle height adjusting actuator 11 side is not drained from the drain circuit 8, and the vehicle height adjusting actuator 11 holds the hydraulic pressure when the engine is stopped.

Therefore, when the engine is stopped, the vehicle height adjustment actuator 11
Does not drive neither the vehicle height rising side nor the vehicle height falling side,
It is possible to obtain the feature that the vehicle height when the engine is stopped, that is, the vehicle posture does not change.

Although the embodiment has been described above with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope of the invention, the invention is included.

For example, in the embodiment, the cut valve is closed for a predetermined time after the engine is stopped, but it may be closed during the engine is stopped.

Also, the cut valve and the unload valve used normally closed valves respectively, but by using normally closed valves and controlling,
It may be normally closed.

Furthermore, in the embodiment, the vehicle height adjusting actuators are provided at the respective positions of the four wheels so as to operate according to the change in the acceleration with respect to the vehicle body. However, the number and the content of the control are not limited to this, and for example, A device that simply adjusts the vehicle height according to the vehicle weight may be used.

(Effect of the Invention) As described above, in the vehicle height adjusting device of the present invention,
The vehicle height (vehicle attitude) is maintained as it is when the engine is stopped, and the effect that the vehicle height does not change is obtained.

[Brief description of drawings]

FIG. 1 is an overall view showing a hydropneumatic suspension system to which a vehicle height adjusting device of an embodiment of the present invention is applied, FIG. 2 is a timing chart showing the operation of each part of the embodiment device at the time of engine start, and FIG. 5 is a timing chart showing the operation of each part when the engine is stopped. 1 ... Pump 2 ... Engine 3 ... (Drain) Tank 4a, 4b ... Accumulator 5 ... Hydraulic pressure supply circuit 6 ... Pressure control valve 7 ... First check valve 8 ... Drain circuit 9 ... Output circuit 11 ... Vehicle height adjusting actuator 13 … Second check valve 14… Cut valve 15… Open / close control circuit 16… Liquid release circuit 17… Unload valve

Claims (1)

[Scope of utility model registration request] 1. An accumulator for temporarily accumulating hydraulic pressure supplied from an engine-driven pump, and an accumulator connected via a hydraulic pressure supply circuit and also connected to a drain circuit side so that the output hydraulic pressure is A pressure control valve for controlling, a vehicle height adjusting actuator that is driven by the output hydraulic pressure of the pressure control valve and is capable of controlling the vehicle height and posture, and an accumulator provided between the accumulator and the pressure control valve of the hydraulic pressure supply circuit. And a first check valve for preventing backflow to the side of the drain circuit, and is provided in the drain circuit and is opened in the hydraulic pressure supply circuit closer to the accumulator than the first check valve when hydraulic pressure is generated and closed when non-hydraulic pressure is generated. The second check valve for preventing backflow to the pressure control valve side, and the hydraulic pressure relief circuit for connecting the hydraulic pressure supply circuit located on the accumulator side of the first check valve and the drain tank to the hydraulic pressure relief circuit. An unload valve provided to open and close the passage, a cut valve provided to the drain circuit between the pressure control valve and the second check valve to open and close the drain circuit, and the unload valve when the engine is driven. An open / close control circuit that closes the load valve and the cut valve, and opens the unload valve and closes the cut valve for at least a predetermined time when the engine is stopped. A vehicle height adjusting device characterized in that