JPH0712084Y2 - 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, JP-A-62-96123
There is known one used in a vehicle height adjusting type roll control device described in Japanese Patent Laid-Open Publication No.

This conventional device is connected to an accumulator for temporarily accumulating hydraulic pressure supplied from an engine-driven pump and a hydraulic pressure supply circuit connected to the accumulator, and selectively connected to the hydraulic pressure supply circuit and the drain circuit. A pressure control valve that controls the output hydraulic pressure and a vehicle height adjusting actuator that is driven by the output hydraulic pressure of the pressure control valve and that can change the vehicle height are provided. 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, since the drain circuit does not have a check valve for leak prevention, when the engine is stopped, the hydraulic pressure in the vehicle height adjusting actuator and the accumulator is reduced. Was drained and the vehicle height gradually decreased to the minimum vehicle height.

Further, as a means for preventing this, it is conceivable to provide the drain circuit with a check valve for pilot-type leakage prevention which is opened by the accumulator pressure. According to this means, it is possible to prevent a decrease in vehicle height after the check valve is closed.

However, even with this means, the check valve does not close while there is accumulator pressure after the engine is stopped, and during that time, leakage of the hydraulic pressure in the vehicle height adjustment actuator from the pressure control valve continues and the vehicle height does not drop. I couldn't escape.

(Means for Solving Problems) In view of the problems as described above, the present invention aims to provide a vehicle height adjusting device in which the vehicle height does not decrease after the engine is stopped. In order to achieve the purpose, the following solutions were adopted.

That is, in the present invention, an accumulator that temporarily stores the hydraulic pressure supplied from the engine-driven pump, and a first check valve provided between the accumulator and the pump,
It is connected to the accumulator via a hydraulic pressure supply circuit and also connected to the drain circuit side, and is driven by the pressure control valve for controlling the output hydraulic pressure, and the output hydraulic pressure of the pressure control valve, and the vehicle height and attitude A vehicle height adjusting actuator, a pilot type second check valve which is provided in the drain circuit and closes when the accumulator pressure becomes a predetermined value or less, and a valve closing sensor for detecting a closed state of the second check valve, , An engine sensor for detecting engine stop, and normal operation control of the pressure control valve based on a signal from a predetermined input sensor in the engine driven state, and after the engine stop is detected by the engine sensor, A key for continuing the control operation of the pressure control valve until the closed state of the second check valve is detected by the valve close sensor. And a means and a control circuit for performing off control.

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

(A) During normal operation (when the engine is driven) When the pump is driven by the engine, the generated hydraulic pressure is the first
It is sent to the accumulator through the check valve and stored therein, and is also supplied to the pressure control valve through the hydraulic pressure supply circuit.

Further, the second check valve is opened by the generation of the accumulator pressure, and the drain circuit is in a drainable state, whereby the pressure control valve can be operated.

The pressure control valve is operated to adjust the vehicle height to a target vehicle height based on an input signal from a predetermined input sensor such as a vehicle height sensor or a vehicle height setting operation switch, and the output hydraulic pressure is controlled to control the vehicle height. The adjusting actuator is driven by this output hydraulic pressure,
The target vehicle height is adjusted.

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) During key-off control (when the engine is stopped) When the engine is stopped, the hydraulic pressure supplied from the pump decreases, which prevents the first check valve from closing and the accumulator pressure from flowing out to the pump side.

Further, when the engine stop is detected by the signal from the engine sensor, the control circuit starts the key-off control, and the pressure control valve uses the hydraulic pressure stored in the accumulator even after the engine stop, and Continue the vehicle height adjustment control.

After that, when the hydraulic pressure stored in the accumulator leaks from the pressure control valve to the drain circuit during the key-off control, and the accumulator pressure drops below a predetermined level, the second check valve is closed. Therefore, the drain circuit is shut off, and the hydraulic pressure in the hydraulic pressure supply circuit and the actuator is confined between the first check valve and the second check valve.

At the same time, when the valve closing sensor detects that the second check valve is in the closed state, the key-off control is stopped in the control circuit and the operation of the pressure control valve is stopped. As described above, in the present invention, since the pressure control valve continues to operate (key-off control is performed) even after the engine is stopped, the hydraulic pressure in the vehicle height adjusting actuator is not drained at the same time when the engine is stopped. Therefore, the vehicle height does not decrease immediately after the engine is stopped.

Furthermore, this key-off control is designed to stop after the accumulator pressure falls below a predetermined level and both check valves are closed, so the hydraulic pressure in the vehicle height adjustment actuator is drained even after the pressure control valve has stopped operating. The vehicle height does not decrease. In addition, even after this, even if the hydraulic pressure moves between the accumulator side and the vehicle height adjusting actuator side via the pressure control valve over time, the accumulator pressure when both check valves are closed becomes a predetermined pressure in this way. By setting it, it is possible to suppress the movement of the hydraulic pressure to the minimum, and it is possible to prevent the hydraulic pressure stored in the accumulator from moving to the vehicle height adjusting actuator in a large amount and increasing the vehicle height.

Therefore, it is possible to prevent the vehicle height from changing substantially even after a lapse of time after the engine is stopped.

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

First, the configuration will be described.

FIG. 1 is an overall view showing a vehicle height adjusting device according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a pump which is driven by an engine 2 and sucks and discharges hydraulic fluid from a tank 3. The hydraulic pressure generated in (1) is pulsatingly absorbed by the sub accumulator 4a, and is temporarily stored in 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, there is provided a first check valve 7 for preventing backflow of the working fluid from the accumulator 4b side to the pump 1 (accumulator 4a) side.

The pressure control valve 6 is connected to a drain circuit 8 and an output circuit 9, and the output circuit 9 is selectively connected to the hydraulic pressure supply circuit 5 and the drain circuit 8 to output the output hydraulic pressure to the output circuit 9. It is a well-known valve having a valve body, a solenoid, and a spool, which are not shown in the drawing, which is a valve for setting a predetermined control hydraulic pressure according to a control command current value ic from the control circuit 10, and a detailed description thereof will be 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 vehicle body side 101 on the spring and the axle side 102 on the unsprung side, and is operated by the hydraulic pressure output from the pressure control valve 6. The vehicle height is adjusted, and the higher the pressure, the higher the vehicle height.

The vehicle height adjusting actuators 11 are provided at the respective positions of the four wheels of the vehicle body (not shown), and the pressure control valves 6 are also provided independently corresponding to these actuators. It is possible to control the posture of the vehicle by adjusting. Further, in the middle of the output circuit 9, a sub accumulator 4c that functions as another suspension spring is provided.

The control circuit 10 is connected to an input sensor group 12 for attitude control, which is composed of a G sensor for detecting accelerations occurring in the front, rear, left, right, and up and down directions of the vehicle body, a vehicle speed sensor, a vehicle height sensor, and the like. Based on the signals from the sensor group 12, the output hydraulic pressure to each posture control actuator 11 is calculated so as to bring the vehicle body posture to a target state such as a horizontal state, and the pressure control valve 6 is calculated based on the calculation result. The control command signal ic is output.

Further, an ignition switch 15 is connected to the control circuit 10. The ignition switch 15 is used as an engine sensor for detecting the driving and stopping of the engine 2, and when the ignition switch 15 is ON, the engine drive is detected, and when it is OFF, the engine stop is detected.

The drain circuit 8 is connected from the pressure control valve 6 to the tank 3
A second check valve 13 is provided on the way to the circuit.

The second check valve 13 operates by using the hydraulic pressure of the hydraulic pressure supply circuit 5 at a position between the accumulator 4b and the first check valve 7 as a pilot pressure, and when the pilot hydraulic pressure becomes a predetermined value or less, the second check valve 13 closes the drain circuit 8. Cut off. Incidentally, this pilot hydraulic pressure is
For example, it is set to a hydraulic pressure height required to maintain a predetermined vehicle height such as the most average vehicle height.

A pressure sensor 14 is provided in the drain circuit 8 between the second check valve 13 and the pressure control valve 6. The pressure sensor 14 is provided as a valve closing sensor for detecting the closed state of the second check valve 13, that is, when the drain circuit 8 which is the drain pressure in the normal state closes the second check valve 13, both the checks are performed. Paying attention to the fact that the hydraulic pressure rises due to the hydraulic pressure being accumulated between the valves 7 and 13, and when the drain circuit 8 has exceeded the predetermined hydraulic pressure, it is detected that the second check valve 13 is in the closed state. It is something that is done.

Next, the operation of the first embodiment will be described.

(B) Normal time (when engine is driven) When the ignition switch 15 is turned on and the engine 2 is started, the pump 1 is driven by the engine 2 and the hydraulic pressure in the hydraulic pressure supply circuit 5 rises, and the first check valve 7 Is opened, and the hydraulic pressure is stored in the accumulators 4a and 4b and is supplied to the pressure control valve 6.

Then, in the control circuit 10, the ignition switch 15 is turned on.
As a result, the drive of the engine 2 is detected, and the normal operation control for adjusting the vehicle height is started based on the signal from the input sensor group 12, and the control command signal ic is output to the pressure control valve 6.

As a result, the hydraulic pressure of the output circuit 9 is controlled, the vehicle height adjusting actuator 11 is driven, and the vehicle height is adjusted to the target vehicle height.

On the other hand, in this state, in the drain circuit 8, the second check valve 13 receives the pilot pressure from the hydraulic pressure supply circuit 5, and the drain from the pressure control valve 6 is allowed to open.

(B) Key-off operation (when engine drive is stopped) The operation when the engine 2 is stopped will be described with reference to the time chart of FIG.

When the ignition switch 15 is turned off (a) and the engine 2 is stopped (b), the first check valve 7 is closed (c) due to the decrease in the supply fluid pressure. Further, when the ignition switch 15 is turned off, the control circuit 10 detects that the engine is stopped and starts the key-off control. The key-off control is control for continuing the vehicle height control even after the engine is stopped.

Therefore, the control command signal ic continues to be output, and the pressure control valve 6
The vehicle height until then is maintained by the operation of.

That is, the hydraulic pressure is stored in the accumulator 4b,
The pressure control valve 6 controls the output hydraulic pressure by selectively connecting the output circuit 9 to the hydraulic pressure supply circuit 5 which is the stored hydraulic pressure and the drain circuit 8.

After that, the operation of this pressure control valve 6 and this pressure control valve 6
When the hydraulic pressure in the accumulator 4b is reduced (d) due to liquid leakage from the hydraulic pressure supply circuit 5 and the hydraulic pressure supply circuit 5 (pilot pressure) drops below a predetermined pressure, the second check valve 13 is closed (f) and the hydraulic pressure is supplied. Circuit 5 and vehicle height adjustment actuator 11
The hydraulic pressure inside is contained between both check valves 7 and 13.

The hydraulic pressure in the drain circuit 8 increases due to this hydraulic pressure containment, and (e) it is detected that the second check valve 13 is closed, and the control circuit 10 stops the key-off control after a fixed time t from this ( g).

Therefore, even if the operation of the pressure control valve 6 is stopped, the hydraulic pressure in the vehicle height adjusting actuator 11 is not drained, and the vehicle height becomes a predetermined height based on the hydraulic pressure in the vehicle height adjusting actuator 11. It has the characteristic of being maintained.

Further, since the inside of the accumulator 4b is also maintained at a predetermined pressure, the pressure control valve 6 leaks after this, and hydraulic pressure moves between the accumulator 4b, the vehicle height adjusting actuator 11, and the drain circuit 8. However, it is an extremely slight change that slightly approaches the vehicle height based on the hydraulic pressure of the accumulator 4b. Then, by setting the hydraulic pressure of the accumulator 4b to a hydraulic pressure that maintains an average vehicle height, this change can be minimized.

Therefore, even if the engine 2 is stopped and a long time elapses, there is almost no change in the vehicle height, and at the same time, there is almost no change in the vehicle attitude.

Further, since the pressure sensor (valve closing sensor) 14 is provided so that the second check valve 13 can be accurately grasped when it is closed, the operation time of the pressure control valve 6 is minimized and the engine 2 is stopped. It has a feature that power consumption afterwards can be suppressed.

Next, a second embodiment shown in FIG. 3 will be described. This embodiment is an example in which a pressure sensor 214 as a valve closing sensor is provided in the accumulator 4b.

That is, it is detected that the second check valve 13 is closed when the accumulator 4b, which normally has a high hydraulic pressure (above a predetermined pressure), drops to the pilot pressure (predetermined pressure) at which the second check valve 13 closes. It is something that is done.

The rest of the configuration and operation are the same as in the first embodiment, so a description is omitted.

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 pressure sensor is provided as the valve closing sensor, but a switch-shaped element including a contact or the like may be directly attached to the second check valve.

Further, although the ignition switch is used as the engine sensor in the embodiment, any engine tachometer, oil pump, alternator, or the like may be used as long as the engine sensor detects the stop of the engine.

(Effect of the Invention) As described above, in the vehicle height adjusting device of the present invention,
The vehicle height does not drop immediately after the engine is stopped,
Even after that, it is possible to obtain an effect that the vehicle height can be hardly changed.

[Brief description of drawings]

FIG. 1 is an overall view showing a vehicle height adjusting device of a first embodiment of the present invention, FIG. 2 is a timing chart showing the operation of each part of the embodiment device when the engine is stopped, and FIG. 3 is a second embodiment device. FIG. 1 …… Pump 2 …… Engine 4b …… (Main) accumulator 5 …… Hydraulic pressure supply circuit 6 …… Pressure control valve 7 …… First check valve 8 …… Drain circuit 9 …… Output circuit 10… … Control circuit 11 …… Vehicle height adjustment actuator 13 …… Second check valve 14,214 …… Pressure sensor (valve closing sensor) 15 …… Ignition switch (engine sensor)

Claims (3)

[Scope of utility model registration request] 1. An accumulator for temporarily storing hydraulic pressure supplied from an engine-driven pump, a first check valve provided between the accumulator and the pump, and a hydraulic pressure supply circuit connected to the accumulator. In addition, the pressure control valve connected to the drain circuit side to control the output hydraulic pressure, the vehicle height adjusting actuator driven by the output hydraulic pressure of the pressure control valve, and capable of controlling the vehicle height and the posture, A pilot type second check valve provided in a circuit and closed when the accumulator pressure becomes lower than a predetermined level; a valve closing sensor for detecting a closed state of the second check valve; and an engine sensor for detecting an engine stop, While the engine is running, the normal operation control of the pressure control valve is performed based on the signal from the predetermined input sensor, and A control circuit for performing a key-off control for continuing the control operation of the pressure control valve from when the stop of the driving of the engine is detected by the valve close sensor to when the closed state of the second check valve is detected by the control circuit. A vehicle height adjusting device characterized in that 2. The valve closing sensor is a pressure sensor provided in a hydraulic pressure supply circuit between the accumulator and the pressure control valve, and a second check is performed when the hydraulic pressure supply circuit pressure becomes equal to or lower than a pilot pressure. The vehicle height adjusting device according to claim 1, wherein the utility model registration is a sensor for detecting the closed state of the valve. 3. The valve closing sensor is a pressure sensor provided in a drain circuit between the pressure control valve and a second check valve, and the second check is performed when the drain circuit pressure exceeds a set pressure. The vehicle height adjusting device according to claim 1, wherein the utility model registration is a sensor for detecting the closed state of the valve.