JP2942890B2 - Height adjustment device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle height adjusting device that is interposed between a vehicle body and an axle of a vehicle such as an automobile and adjusts a vehicle height while suspending the vehicle body.

[Conventional technology]

For example, a system shown in FIG. 3 has been developed as this kind of vehicle height adjusting device.

In this configuration, a hydraulic source composed of a pump 3 and a tank 12 is connected to a vehicle height adjusting cylinder 10 of a left and right suspension device 15 via a main circuit 13, and the suspension device 15 includes a vehicle height adjusting cylinder 10 and a suspension spring 14. ing.

When adjusting the vehicle height, the controller 9 controls the motor 2
, The high-pressure oil is supplied to the oil chamber of the cylinder 10 via the check valve 5 and the main circuit 13,
The piston rod 16 extends to increase the vehicle height.

Similarly, when the pump 3 is reversed by the controller 9, the check valve 5 is opened by the pilot pressure, and the pump 3 sucks oil in the cylinder 10 from the main circuit 13 and discharges the oil to the tank 12 to lower the vehicle height.

The internal pressure when the vehicle height is increased is detected by the pressure switch 7, and the internal pressure when the vehicle height is decreased is detected by another pressure switch 8, and when the pressure reaches a predetermined pressure, the motor 2 and the pump 3 are stopped by respective signals, and are fixed. After the adjustment, the main circuit 13 is closed by the check valve 5 and the relief valve 6, and the vehicle height is maintained.

When the discharge pressure of the pump is excessive, the
The oil in the system is opened and discharged to the tank 12 when the internal pressure rises above a predetermined pressure due to a rise in temperature, or when an excessive external force is applied to the cylinder 10 due to vibration or the like.

[Problems to be solved by the invention]

According to the above-described vehicle height adjustment device, when the vehicle is running with the vehicle height raised, if excessive external force due to vibration from the road surface acts on one or both cylinders 10, the piston rod 16 is compressed. Then, the oil in the oil chamber in the cylinder 10 is discharged from the main circuit 13 through the relief valve 6, and the cylinder 10 is compressed by the amount of the discharged oil and the vehicle height falls below a desired position. Also, since the left and right cylinders 10, 10 are in communication, if the external force acting on each cylinder 10, 10 is unbalanced when the oil is discharged through the oil via the relief valve 6, a large One cylinder 10 which received external force
However, the car body tilts due to compression, which makes the maneuverability and riding comfort worse.

Therefore, in order to avoid such a problem, if the set pressure of the relief valve 6 is increased, it becomes difficult to relieve the high pressure, so that the pressure resistance of each device in the system must be increased. Similarly, it is sufficient to increase the diameter of the cylinder 10 to increase the volume of the oil chamber. To do so, use a large-capacity motor 2 and pump 3 to supply and discharge large-capacity oil for the same time. Inevitably, the whole system becomes large.

Accordingly, an object of the present invention is to provide an impact effect against a large input to the system when the vehicle height is increased, to prevent an increase in the cylinder internal pressure and the circuit internal pressure, and to prevent a decrease in the vehicle height by eliminating the supply oil. It is another object of the present invention to provide a vehicle height adjusting device that prevents the body from leaning even when an unbalanced external force acts on a plurality of vehicle height adjusting cylinders.

[Means for solving the problem]

Means of the present invention for solving the above object have a hydraulic source and a vehicle height adjusting cylinder, and a hollow piston rod is movably inserted into the vehicle height adjusting cylinder via a piston, In a vehicle height adjustment device in which an oil chamber is partitioned in a vehicle height adjustment cylinder and a hydraulic pressure source and an oil chamber are connected via a main circuit, an accumulator is provided in a piston rod, and the oil chamber is provided in a piston. First and second branch circuits connected to the accumulator are provided in parallel, a relief valve is provided in the first branch circuit so as to be openable and closable, and a check valve is provided in the second branch circuit so as to be openable and closable. It has a damper function of absorbing an excessive impact force.

(Operation)

When an excessive external force acts on the cylinder for adjusting the vehicle height, the cylinder is compressed, and the discharged oil is accumulated in the accumulator through a relief valve. When the excessive external force is released, the internal pressure of the cylinder is reduced to the vehicle height holding pressure. Returning, the oil is returned from the accumulator to the cylinder via the check valve, and the cylinder returns to the initial state and maintains the vehicle height in a stable state.
When the cylinder is compressed, a cushioning effect is exerted to reduce the rise in the cylinder and circuit internal pressure. When expanding and contracting, it also exhibits a buffering effect.

〔Example〕

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

FIG. 1 shows a hydraulic circuit of a system according to one embodiment of the present invention.

The system consists of a power unit 1 and left and right suspensions 15,15
And a controller 9.

The power unit 1 includes a motor 2 as a hydraulic pressure source and a pump 3
And check valves 4a and 4b, a pilot check valve 5, a relief valve 6, a pressure switch 7, 8, a throttle 11, and a tank 12.
Is driven, and the pump 3 is driven in the forward or reverse direction via the motor 2 by a signal from the controller 9.

The pump 3 and the tank 12, which are hydraulic pressure sources, are connected to the main circuits 13, 13
Are connected to oil chambers 10a, 10b of the vehicle height adjusting cylinders 10, 10, respectively.

The suspension device 15 includes a cylinder 10 for suspending the vehicle body and a suspension spring 14.A piston rod 16 is inserted into the cylinder 10 via a piston so as to be movable up and down, and the piston partitions oil chambers 10a and 10b. The oil chambers 10a and 10b communicate with each other via a throttle 17.

The check valve 5 is provided in the middle of the main circuit 13, and the relief valve 6 is provided in a circuit between the main circuit 13 and the tank 12.

 The above configuration is the same as the conventional one.

In the present invention, two first branch circuits are further added to the main circuit 13.
18 and a second branch circuit 19 are provided in parallel, these branch circuits 18 and 19 are connected to an accumulator 20, a relief valve 21 is provided in the first branch circuit 18, and a second branch circuit 19 is provided in the second branch circuit. Is provided with a check valve 22.

The relief set pressure P1 of the relief valve 21 corresponds to a general excessive input, that is, a large input when traveling on a rough road, and the relief set pressure P2 of the other relief valve 6 corresponds to a pressure for protecting the system. The relationship with holding force P3 is P2> P1
> P3.

When adjusting the vehicle height, the controller 9 controls the motor 2
, The high pressure oil is supplied to the oil chamber 10a of the cylinder 10 via the check valve 5 and the main circuit 13, and the piston rod 16 is extended to increase the vehicle height.

Similarly, when the pump 3 is reversed by the controller 9, the check valve 5 is opened by the pilot pressure, and the pump 3 sucks oil in the cylinder 10 from the main circuit 13 and discharges it to the tank 12 to lower the vehicle height.

The internal pressure when the vehicle height is increased is detected by the pressure switch 7, and the internal pressure when the vehicle height is decreased is detected by another pressure switch 8, and when the pressure reaches a predetermined pressure, the motor 2 and the pump 3 are stopped by respective signals, and are fixed. After the adjustment, the main circuit 13 is closed by the check valve 5 and the relief valve 6, and the vehicle height is maintained.

When the discharge pressure of the pump is excessive, the
The oil in the system is opened and discharged to the tank 12 when the internal pressure rises to a predetermined pressure or more due to a rise in temperature, or when an excessive external force is applied to the cylinder 10 due to vibration or the like.

When the vehicle is running with the vehicle height set to a certain height and an excessive external force acts on the cylinder 10 due to vibration from the road surface or the like, the piston rod 16 is compressed, and the internal pressure of the oil chamber 10a is reduced. As the pressure rises, the relief valve 21 is opened and discharged to the accumulator 21 to accumulate the pressure.

When the cylinder 10 is compressed when an external force acts, the cylinder 10 absorbs the external force and reduces the impact, thereby exhibiting a cushioning effect.

When the external force is released, the internal pressure of the cylinder 10 returns to a predetermined vehicle height holding force, the oil stored in the accumulator 20 is returned from the check valve 19 into the oil chamber 10a, and the cylinder 10 expands and returns to the original state. Return, the vehicle height is returned to a predetermined height and stably maintained.

Excessive external force acts due to unsprung vibration. When the body rises and the input to the cylinder is reduced, the internal pressure in the cylinder 10 drops to a greater extent than the vehicle height holding force, so the sealing pressure of the accumulator 20 is maintained at the vehicle height. Even if the pressure is lower than the pressure, the replenishment can be sufficiently performed. In other words, since the accumulator 20 and the oil chamber 10a are shut off by the relief valve 21 and the check valve 22,
Regardless of the holding force of the cylinder 10, the pressure of the accumulator 20 may be compensated so that the pressure in the cylinder 10 is restored after the relief valve 21 operates after the above operation.

The present invention, as shown in the embodiment of FIGS. 1 and 2, includes first and second branch circuits 18, 19, a relief valve 21, and a check valve 2.
2 is incorporated in the vehicle height adjusting cylinder 10, and the operation and effect are as described above.

In FIG. 1, parallel first and second branch circuits 18, 19 branched from an oil chamber 10a in a piston rod 16 inserted into a cylinder 10, and an accumulator connected to the branch circuits 18, 19 20, a relief valve 21 and a check valve 22 provided in the first and second branch circuits 18 and 19 are incorporated.

When the cylinder 10 is compressed by an excessive external force acting thereon, the oil in the main circuit 13 and the oil chamber 10a is accumulated in the accumulator 20 via the relief valve 21, and when the external force is released, the accumulated oil is accumulated in the check valve 22. To the oil chamber 10a, and the cylinder 10 returns to the normal position. In this embodiment, since each member such as the accumulator 20 is incorporated in the piston rod 16 in the cylinder 10, the number of pipes is small and the structure is compact.

FIG. 2 shows an embodiment of the cylinder 10 of FIG. 1 and an accumulator incorporated therein.

The cylinder 10 is sealed by a cylinder head 23, and the cylinder head 23 has a port 2 for communicating the main circuit 13 with the oil chamber 10a.
4 is formed, and the cylinder 10 is connected to the vehicle body via the cylinder head 23 and the bolt 39.

A hollow piston rod 16 is movably inserted into the cylinder 10 via a piston 25, a seal 26, and a bearing 27, and the piston 25 is provided in the cylinder 10 with two oil chambers 10a, 10b.
The two oil chambers 10a and 10b communicate with each other through an orifice 17 (not shown) formed in the piston 25.

Free piston 28 slidable inside piston rod 16
And a fixed bottom 29 is inserted, an oil chamber 30 is defined between the free piston 28 and the piston 25, and the free piston
A gas chamber serving as the accumulator 20 is defined between the bottom 28 and the bottom 29.

A spring seat 32 and a bump rubber 33 are attached to the bottom 29 via a bottle 31. The upper part of the spring seat 32 carries the upper part of the suspension spring 14.

A relief bolt 34 is inserted and fixed in the center of the piston 25. Ports 35 and 36, which are first branch circuits, are formed in the relief bolt 34, and the ports 35 and 36 communicate the oil chambers 10a and 30.

At the outlet end of the port 35, a ball-shaped valve element serving as the relief valve 21 urged by a spring 37 is disposed so as to be openable and closable.

The piston 25 has a port 38 as a second branch circuit communicating the oil chambers 30 and 10a, and a leaf valve as a check valve 22 biased by a spring is provided at the outlet end of the port 38 so as to be openable and closable. I have.

When oil in the oil chamber 10a is supplied through the main circuit 13, the piston rod 16 extends through the piston 25 to increase the vehicle height, and when a certain amount of oil in the oil chamber 10a is removed, the suspension spring 1
The piston rod 16 is compressed by the spring force of 4, and the vehicle height is reduced. The height of the vehicle is determined by the balance between the internal pressure due to the amount of oil in the oil chamber 10a and the spring force of the suspension spring 14.

When an external force acts on the cylinder 10, the piston rod 16 is compressed, and the compressed volume of oil is introduced into the oil chamber 30 by opening the relief valve 21, and the free piston 28 is further lowered by the internal pressure of the oil chamber 30, and the gas in the accumulator 20 The chamber is compressed and accumulated,
When the external force is released, the free piston
28 is pushed up, the oil in the oil chamber 30 pushes open the check valve 22 from the port 38 and returns to the oil chamber 10a, and the gas pressure in the gas chamber acts on the oil chamber 10a, thereby returning the cylinder 10 to the original position. It is.

〔The invention's effect〕

According to the present invention, the following effects are obtained when the vehicle height is increased.

When an excessive external force acts on the vehicle height adjustment cylinder, the oil in the cylinder is accumulated in the accumulator and the oil is returned to the cylinder when the external force is released.Therefore, the oil in the system does not decrease. The quantity can be held.

When an external force acts on the cylinder, the cylinder compresses or expands, so that a cushioning effect can be exhibited.

Even if an external force acts on the cylinder and the cylinder expands or contracts, the change in oil amount is compensated by the accumulator, so the cylinder returns to the original position after the release of the external force, and the vehicle height can always be maintained at a predetermined height. .

Increase the set pressure of the protection relief valve in the system, increase the pressure resistance of each device in the system,
Since it is possible to cope with excessive external force without increasing the cylinder diameter, the entire apparatus can be designed to be small and compact, and is excellent in economy and workability.

When there is a vehicle adjusting cylinder on the left and right sides of the vehicle, even if an excessive external force acts on only one of the cylinders, this cylinder can immediately return to the vehicle height-up state, so that the leaning of the vehicle body can be prevented.

Since the relief valve, the check valve, the accumulator, and the like are incorporated in the piston and the piston rod, the number of pipes is small and the structure is compact. In addition, there are few pipes, the oil path is short, stable characteristics are obtained without being affected by the oil path resistance, and the response is excellent.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit according to an embodiment of the present invention, FIG. 2 is a vertical sectional front view of a cylinder used in the hydraulic circuit of FIG.
The figure shows a conventional hydraulic circuit. [Description of Signs] 2 ... Motor 3 ... Pump 10 ... Vehicle height adjustment cylinder 13 ... Main circuit 16 ... Piston rod 18 ... First branch circuit 19 ... Second branch circuit 20 ... Accumulator 21 Relief valve 22 Check valve 25 Piston

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60K 17/056 F16F 9/00

Claims (1)

(57) [Claims] A hollow piston rod is movably inserted through a piston into a vehicle height adjustment cylinder, and the piston has an oil chamber in the vehicle height adjustment cylinder. In a vehicle height adjustment device in which a hydraulic pressure source and an oil chamber are connected via a main circuit, an accumulator is provided in a piston rod, and a first and a second pistons connect the oil chamber to the accumulator in the piston. A branch circuit is provided in parallel, a relief valve is provided in the first branch circuit so as to be openable and closable, a check valve is provided in the second branch circuit so as to be openable and closable,
A vehicle height adjustment device with a damper function that absorbs excessive impact force when the vehicle height is increased.