JPH07164853A - Vehicle height adjustment device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a vehicle height adjusting device capable of suppressing the occurrence of zero down of a gas spring, optimizing a vehicle height adjusting time, and reducing the cost. [Structure] A supply / discharge oil switching valve 11 for switching supply / discharge of oil liquid to / from the hydraulic cylinder 1 according to pilot pressure is provided. One end of a cylinder side pilot passage 31 provided in the oil supply / exhaust oil switching valve 11 is connected to a communication portion 3 between the gas spring 2 and the hydraulic cylinder 1, the internal pressure of the communication portion 3 is used as a pilot pressure, and the pilot pressure is equal to or lower than a predetermined pressure. When, the discharge of the oil liquid from the hydraulic cylinder 1 through the supply / discharge oil switching valve 11 is stopped. Zero-down of the gas spring 2 can be prevented, and even when lowering the vehicle height to the cylinder stroke end, it is necessary to return the vehicle height from the cylinder stroke end state to the normal vehicle height without draining oil liquid more than necessary. It is possible to reduce the amount of oil liquid required, which in turn shortens the vehicle height adjustment time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle height adjusting device for adjusting the vehicle height of a vehicle such as an automobile.

[0002]

2. Description of the Related Art Conventionally, in order to improve steering stability, running performance, riding comfort and entry / exitability in response to changes in road surface conditions such as flat paved roads and unpaved roads with large unevenness, and changes in load, vehicle height is improved. There is known a vehicle height adjusting device for adjusting.

As an example of this type of vehicle height adjusting device, a hydraulic cylinder communicating with a gas spring is provided between a vehicle body side and a wheel side, and a hydraulic source is connected to the hydraulic cylinder via a main pipe line. An on-off valve that is opened and closed by a controller is provided in the middle of the main pipeline, and an oil liquid return pipeline to the reservoir tank is provided at a portion of the main pipeline between the on-off valve and the hydraulic pressure source. A device with an electromagnetic relief valve in the middle of the return line and a vehicle height sensor on the vehicle body side (Japanese Patent Application No. 4-9363).
(See No. 1).

In this vehicle height adjusting device, when the detected value of the vehicle height sensor is smaller than the preset reference value (lower than the reference vehicle height), the controller opens the on-off valve,
In addition, the electromagnetic relief valve is closed to supply the pressure oil from the hydraulic source to the hydraulic cylinder, thereby extending the hydraulic cylinder and increasing the vehicle height. If the detected value of the vehicle height sensor is higher than the reference value (higher than the reference vehicle height), the controller opens the on-off valve and the electromagnetic relief valve to return the oil liquid in the hydraulic cylinder to the tank. Reduce the vehicle height by shortening the cylinder. Then, when the detection value of the vehicle height sensor reaches the reference value, the on-off valve is closed.

Further, when the vehicle passes through a lying tree, for example, the vehicle liquid is discharged to the cylinder stroke end to make the vehicle height extremely low. In this case, the detected value of the vehicle height sensor is The hydraulic cylinder is shortened by discharging the oil liquid for a predetermined time after the lower limit value is reached.

[0006]

By the way, the internal pressure of the hydraulic cylinder and the cylinder descending speed change due to the load fluctuation of the vehicle. Therefore, in the above-described conventional vehicle height adjusting device, the internal pressure of the hydraulic cylinder becomes equal to or lower than the enclosed pressure of the gas spring by continuing to discharge the oil liquid for a predetermined time in an attempt to discharge the oil liquid to the cylinder stroke end, that is, Sometimes it went down to zero. Then, if zero reduction occurs, when returning to the normal vehicle height (near the center of the cylinder stroke), extra oil liquid must be supplied by the volume change of the gas spring, and it takes a long time to adjust the vehicle height. Or, there was a problem that the hydraulic power source had to have a large capacity. Further, since the control of oil supply / drainage is performed electrically, the cost of the device is high.

The present invention has been made in view of the above points, and can suppress the occurrence of zero down of the gas spring to optimize the vehicle height adjustment time and reduce the vehicle height. The purpose is to provide a device.

[0008]

In order to achieve the above object, the present invention provides a hydraulic cylinder communicating with a gas spring between a vehicle body side and a wheel side, and a main pipeline is provided in the hydraulic cylinder. In the vehicle height adjusting device, in which a hydraulic pressure source and a reservoir tank are connected to each other, and an opening / closing valve that is opened / closed by a controller is provided in the middle of the main pipeline, the vehicle height adjusting device is provided in a portion of the main pipeline between the opening / closing valve and the hydraulic source. An oil supply / exhaust oil switching valve having an oil supply position for communicating the on-off valve with the hydraulic pressure source and an oil discharge position for communicating the on-off valve with a reservoir tank is provided in the hydraulic cylinder. Cylinder side pilot mechanism for urging the oil supply / exhaust oil changeover valve toward the oil supply position side, and hydraulic source side pilot mechanism for urging the oil supply / exhaust oil changeover valve toward the oil discharge position side The pressure of the mechanism and the hydraulic cylinder is set Biasing means for biasing so that the oil supply position against the cylinder side pilot mechanism is characterized in that provided when it becomes less.

[0009]

According to the structure of the present invention, since the supply / discharge switching of the oil liquid in the supply / discharge oil switching valve is performed by the pilot pressure, the switching from the discharge of the oil liquid to the supply can be adjusted according to the pilot pressure. Discharge of oil liquid from the hydraulic cylinder through the oil supply / exhaust oil changeover valve When the pressure of the hydraulic cylinder falls below a predetermined pressure, the discharge of oil liquid from the hydraulic cylinder through the oil supply / exhaust oil changeover valve is stopped. By doing so, it is possible to prevent the internal pressure of the hydraulic cylinder from becoming less than or equal to the predetermined pressure of the gas spring, that is, zero-down.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle height adjusting device according to an embodiment of the present invention will be described below with reference to FIGS. A hydraulic cylinder 1 is interposed between a vehicle body side and a wheel side of a vehicle (not shown) to expand and contract by supplying and discharging oil liquid to adjust the vehicle height. A gas spring 2 containing compressed gas is connected to the hydraulic cylinder 1 via a communication passage 3. A damping valve 4 is provided in the middle of the communication passage 3. The hydraulic cylinder 1, the communication passage 3, the damping valve 4, and the gas spring 2 are provided for each wheel, but only one wheel is shown in the drawing. One end of the main pipe 5 is connected to a portion of the communication passage 3 between the damping valve 4 and the hydraulic cylinder 1, and a pump (hydraulic power source) 6 is connected to the other end of the main pipe 5.
Are connected.

An oil supply / drain valve (open / close valve) 7 for opening / closing the main pipeline 5 is provided in the middle of the main pipeline 5. An oil liquid return pipe 9 to the reservoir tank 8 is connected to the main pipe 5 at a portion between the oil supply / exhaust valve 7 and the pump 6.
A throttle 10 is provided in the oil liquid return line 9. A pilot type supply / discharge oil switching valve 11 having a configuration described later is provided so as to be located in a portion between the oil liquid return pipe 9 and the supply / discharge oil valve 7 in the main pipe 5, and the pilot pressure Accordingly, the supply and discharge of the oil liquid to the hydraulic cylinder 1 can be switched. Oil-liquid return line 9 in the main line 5
A check valve 12 that allows only the flow of the oil liquid to the supply / exhaust oil switching valve 11 is provided between the branch portion and the supply / exhaust oil switching valve 11. In the figure, 13 is a vehicle height sensor.

A controller 15 is provided in connection with a vehicle height sensor 13, a motor 14 for driving the oil supply / drain valve 7 and the pump 6, and a comparison result between a detected value of the vehicle height sensor 13 and a preset reference value. Accordingly, the rotation of the motor 14 and the opening / closing of the oil supply / exhaust oil valve 7 are controlled so that the oil liquid is supplied to and discharged from the hydraulic cylinder 1 to adjust the vehicle height.

The oil supply / drain switching valve 11 includes a housing 18 having a bottomed cylindrical housing body 16 and a lid portion 17 for covering the housing body 16, and a spool 19 slidably housed in the housing body 16. , And a spring 20 as a biasing means for biasing the spool 19 which is interposed between one end side of the spool 19 and the lid portion 17.

A small diameter portion 21 is formed on the other end side of the spool 19, and an annular groove 22 having a predetermined width is formed in the central portion. Between the spool 19 and the lid 17 in the housing 18,
A first chamber 24 as a hydraulic source pilot mechanism is formed,
A second chamber 25 as a cylinder side pilot mechanism is formed between the other end of the spool 19 and the bottom portion 23 of the housing body 16, and a second chamber 25 is formed between the annular groove 22 of the spool 19 and the housing body 16. Three chambers 26 are formed.

The housing body 16 has a pump port 27 connected to the check valve 12 and a throttle in the oil liquid return line 9.
10 Tank port 28 connected to the downstream side and oil supply / drain valve 7
A cylinder port 29 connected to the cylinder pipe 29 and a portion (hereinafter, referred to as a cylinder side pipe line) 30 between the oil supply / exhaust valve 7 and the hydraulic cylinder 1 in the main pipe line 5 are connected via a cylinder side pilot passage 31. Cylinder side pilot passage port 32
A pump-side pilot passage port 34 connected to the first chamber 24 and a branch portion of the oil liquid return pipe 9 in the main pipe 5 via a pump-side pilot passage 33 is formed.

In the oil supply / drain switching valve 11, when the internal pressure of the second chamber 25 is smaller than the combined force of the spring force of the spring 20 and the internal pressure of the first chamber 24, the spool 19 is pushed to the bottom 23 side. The state (the state shown in FIG. 2) is established. In this state, the pump port 27 and the cylinder port are communicated with each other via the third chamber 26, and the force relationship is reversed, so that the spool 19 is located on the lid portion 17 side ( By moving in the right direction in FIG. 2) and moving by a predetermined amount, the communication between the pump port 27 and the cylinder port 29 is blocked, and the cylinder port 29 and the tank port 28 are connected.

In this case, the spring force of the spring 20 is such that the second chamber 25
2 when the internal pressure of the hydraulic cylinder 1, that is, the internal pressure of the hydraulic cylinder 1 drops below a predetermined pressure (here, the value is equivalent to the enclosed pressure of the gas spring 2), the spool 19 moves leftward in FIG. Is not connected to the tank port 28, and the discharge of the oil liquid from the hydraulic cylinder 1 through the supply / discharge oil switching valve 11 can be stopped.

The operation of the vehicle height adjusting device configured as described above will be described.

First, the vehicle height adjustment executed when a load change occurs due to an increase or decrease in the number of passengers will be described.

In the case of normal vehicle height, the second position of the oil supply / drain switching valve 11
Since the internal pressure of the hydraulic cylinder 1 acts on the chamber 25 through the cylinder side pilot passage port 32, the spool 19 moves to the right in FIG. 2 against the force of the spring 20.
Therefore, the cylinder port 29 communicates with the tank port 28,
It is not in communication with the pump port 27.

When the vehicle height becomes lower than the reference vehicle height due to an increase in occupants and the like, and the oil liquid is supplied to the hydraulic cylinder 1, the pump 6 is first activated. When pump 6 is started,
The internal pressure of a portion (hereinafter, referred to as a discharge side pipeline) 35 between the pump 6 and the check valve 12 in the main pipeline 5 rises, and communicates via the pump side pilot passage port 34.
The internal pressure of chamber 24 rises. Therefore, a force due to the pressure difference between the first chamber 24 and the second chamber 25 acts on the spool 19 in the left direction in FIG. 2, the spool 19 moves in the same direction, and the cylinder port 29 becomes the pump port 27. While communicating, tank port 28
Is not in communication with.

Here, when the oil supply / drain valve 7 is opened, the pressure oil from the pump 6 is supplied to the hydraulic cylinder 1, so that the hydraulic cylinder 1 extends and the vehicle height rises. When the vehicle height reaches the reference vehicle height due to the supply of pressure oil from the pump 6, the pump 6 is stopped and the oil supply / drain valve 7 is closed.

When the pump 6 is stopped, the oil liquid in the discharge side pipe line 35 is returned to the reservoir tank 8 via the throttle 10, so that the internal pressure of the discharge side pipe line 35 is reduced, and accordingly, the discharge side pipe line is reduced. The internal pressure of the first chamber 24 communicating with the passage 35 decreases, and the spool
Reference numeral 19 moves to the right in FIG. 2 and is set to a normal vehicle height state (a state in which the cylinder port 29 communicates with the tank port 28 and does not communicate with the pump port 27).

Next, the case where the vehicle height is lowered will be described.

In the normal state, the oil supply / exhaust oil switching valve 11 is
As described above, the cylinder port 29 communicates with the tank port 28 and does not communicate with the pump port 27. Therefore, when lowering the vehicle height, the oil supply / drain valve 7 is opened and the oil liquid in the hydraulic cylinder 1 is returned to the reservoir tank 8.

Next, the operation of further lowering the vehicle height to the cylinder stroke end in order to improve the entry / exitability or to pass through a tree will be described. By the above-described operation for lowering the vehicle height, the hydraulic cylinder 1
When the oil liquid inside is discharged to the reservoir tank 8 and the vehicle height is lowered to the cylinder stroke end, the internal pressure of the hydraulic cylinder 1 is reduced, and at the same time, it communicates with the hydraulic cylinder 1 via the cylinder side pilot passage port 32. The pressure in the second chamber 25 in which it is located also drops. Then, when the internal pressure of the hydraulic cylinder 1 becomes the same as the filling pressure of the gas spring 2, the force in the right direction in FIG. 2 acting on the spool 19 by the internal pressure in the second chamber 25 changes to the left direction in FIG. Since it is smaller than the spring force, the spool 19 moves to the left in FIG. 2, and the cylinder port 29 and tank port
The hydraulic fluid is not communicated with 28, and the discharge of the oil liquid from the hydraulic cylinder 1 is stopped.

Therefore, even when the vehicle height is lowered to the cylinder stroke end, the oil liquid is not discharged more than necessary, and the oil required for returning the vehicle height from the cylinder stroke end state to the normal vehicle height is used. A small amount of liquid is required, and thus the vehicle height adjustment time can be shortened, and the pump 6 can be made as small as necessary.

In the above operation, the example in which the drain oil is stopped when the internal pressure of the hydraulic cylinder 1 becomes equal to the filling pressure of the gas spring 2 has been shown, but the spring for urging the spool 19 is used. The spring force of 20 may be increased so that the oil discharge is stopped at a pressure slightly higher than the filling pressure of the gas spring 2.

[0029]

According to the vehicle height adjusting apparatus of the present invention, the supply / discharge switching of the oil liquid in the supply / discharge oil switching valve is performed by the pilot pressure, and the switching from the discharge of the oil liquid to the supply is adjusted according to the pilot pressure. This allows the oil liquid to be discharged from the hydraulic cylinder through the oil supply / exhaust oil switching valve when the hydraulic cylinder pressure drops below a predetermined pressure. By stopping the discharge, zero down of the gas spring can be prevented. Therefore, even when the vehicle height is lowered to the cylinder stroke end, the oil liquid is not discharged more than necessary, and the oil liquid required when returning the vehicle height from the cylinder stroke end state to the normal vehicle height is It is possible to reduce the amount of the vehicle, which in turn shortens the vehicle height adjustment time and makes the hydraulic power source as small as possible. Furthermore, the control of oil supply / drainage is performed mechanically as compared with the conventional device that electrically controls it using an electromagnetic relief valve, so the controller configuration is simpler. Therefore, the cost of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a piping system diagram showing a vehicle height adjusting device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the oil supply / exhaust oil switching valve of FIG.

[Explanation of symbols]

1 Hydraulic Cylinder 2 Gas Spring 5 Main Line 6 Pump (Hydraulic Source) 7 Supply / Discharge Oil Valve (Open / Close Valve) 11 Supply / Discharge Oil Changeover Valve 15 Controller 24 First Chamber (Hydraulic Source Pilot Mechanism) 25 Second Chamber ( Cylinder side pilot mechanism) 31 Cylinder side pilot passage (Cylinder side pilot mechanism) 33 Pump side pilot passage (Hydraulic pressure source side pilot mechanism)

Claims (1)

[Claims] 1. A hydraulic cylinder communicating with a gas spring is interposed between a vehicle body side and a wheel side, and a hydraulic source and a reservoir tank are connected to the hydraulic cylinder via a main pipe, and the main pipe of the main pipe is connected. In a vehicle height adjusting device provided with an on-off valve that opens and closes by a controller on the way, a refueling position that is provided in a portion between the on-off valve and the hydraulic pressure source of the main pipeline, and that connects the on-off valve and the hydraulic pressure source, A supply / exhaust oil switching valve having an opening / closing valve and an exhaust oil position communicating with the reservoir tank is provided, and the supply / exhaust oil switching valve guides the pressure of the hydraulic cylinder to move the supply / exhaust oil switching valve to the oil supply position side. The cylinder side pilot mechanism for urging, the hydraulic source side pilot mechanism for guiding the pressure of the hydraulic pressure source to urge the oil supply / exhaust oil switching valve to the oil discharge position side, and the pressure of the hydraulic cylinder have become below a predetermined pressure. When the cylinder side pilot mechanism is And a biasing means for biasing the fuel to a refueling position.