JPH0437300B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle height adjustment device used, for example, in a suspension system of an automobile.

There are various types of hydraulic shock absorbers used as actuators for vehicle height adjustment devices. For example, in the conventional example shown in Fig. 1, a rod b is slidably inserted into a cylinder a containing oil, and this rod A piston part e having an orifice c is provided at the tip of the rod b, and oil f and high pressure gas g are accommodated inside the rod b, which communicates with the rod b through the orifice c. Further, a stopper h is provided on the outer periphery of the piston part e to prevent the rod b from coming off. Therefore, there is a wide space between the cylinder a and the rod b in which the stopper h can slide. A gap j is formed, and this gap j is also filled with oil.

The conventional product configured as above has cylinder a
When the rod b expands and contracts, the piston part e moves within the cylinder and oil flows through the orifice c, thereby exerting a damping force.
Further, the amount of oil f in rod b changes according to the amount of expansion and contraction of rod b, and the amount of compression of high pressure gas g changes.

Therefore, the pressure of the oil becomes quite high, and the oil filling the gap j between the rod and the cylinder also becomes high pressure, so in order to prevent oil leakage, a sealing member k with a large interference is installed between the cylinder a and the rod b. It is necessary to provide However, since this sealing member k is a part that can come into sliding contact with rod b, if the interference is made too large, the sliding resistance of rod b will increase, making it difficult for rod b to move, which may adversely affect the characteristics of the shock absorber. This also causes problems such as deterioration of the durability of the sealing member k. Furthermore, as seen in Japanese Patent Publication No. 52-45573, a device in which a plurality of seal members are arranged in the axial direction of the cylinder has been proposed, but this conventional device has an annular oil partition partitioned by each seal member. Since oil pressure is constantly applied to the chamber, the tightness of the seal member must be considerably strong to prevent the oil inside the cylinder from leaking to the outside.

The present invention has been made based on the above circumstances, and its purpose is to provide a vehicle height adjustment device that allows the use of a sealing member with low sliding resistance and allows smooth movement of the rod. It's about doing.

That is, the present invention provides a vehicle height adjustment device that includes a cylinder containing oil, a rod that is slidably inserted into the cylinder and includes a piston having an orifice, and a hydraulic unit that takes oil into and out of the cylinder. A first sealing member on the high-pressure side that allows oil leakage is arranged on the sliding part between the cylinder and the rod, and
A second seal member on the low pressure side is arranged on the leakage side of the seal member, a non-pressurized drain gap opened to the atmosphere is provided between the first and second seal members, and This vehicle height adjustment device is equipped with a leak oil outlet that communicates with a non-pressurized drain gap.

Since the present invention is constructed as described above, even if a seal member with low sliding resistance and small interference is used, oil leaking from this seal member can be discharged from the leak oil outlet. I can do it. Therefore, the pressure on the leak side of the seal member can be prevented from increasing, and even a seal with a small interference margin can exhibit a sufficient sealing effect. Even if oil is discharged from the leak oil outlet, oil can be replenished into the cylinder by the hydraulic unit, so a specified amount of oil can always be secured.

An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a cylinder, and this cylinder 1 is constructed by connecting a first member 1a on the upper side in the figure and a second member 1b on the lower side in the figure. Further, oil 2 is accommodated within the cylinder 1.

A hollow rod 3 is slidably inserted into the cylinder 1. This rod 3 includes a cylindrical rod main body 3a, a piston part 3b provided at the lower end side of the main body 3a in the drawing, and a rod main body 3a.
It is constituted by a rod end portion 3c provided at the upper end side in the figure of a. And the piston part 3b
An orifice 4 is formed in the
Plate valves 5 are installed at the positions where these orifices 4 are provided, so that a flow resistance can be applied to the oil passing through the orifices 4. Further, a free piston 6 is slidably provided within the rod 3, and a gas chamber 7 and an oil chamber 8 are separated by the free piston 6. The gas chamber 7 communicates with a gas inlet 9, while the oil chamber 8 communicates with an oil chamber 1c of the cylinder via the orifice 4, and an oil inlet/outlet 10 communicates with the oil chamber 1c.

A hydraulic unit 12 is connected to the oil inlet/outlet 10 via an oil feed pipe 11. This hydraulic unit 12 is composed of a hydraulic pressure generation source 13, a reservoir tank 14, a directional switching valve 15, etc., and is configured to allow oil to be taken in and out of the oil chamber 1c by switching the directional switching valve 15. .

Further, a stopper 20 is formed on the outer peripheral wall of the rod 3. This stopper 20 is designed to prevent the rod 3 from coming out by hitting the inner end surface 1e of the first member 1a when the rod 3 is expanded beyond a predetermined value. A gap 21 is formed between the rod 3 and the cylinder 1 so that the stopper 20 can move.

At the lower end of the rod 3, there is a first high-pressure side opening that partitions the gap 21 and the oil chamber 1c of the cylinder.
A sealing member 22 connects the end of the rod 3 and the cylinder 1.
It is provided at the sliding part with the inner surface of the Furthermore, a second seal member 23 on the low pressure side, located on the leakage side of the first seal member 22, is provided on the sliding surface between the rod 3 and the inner peripheral portion on the open end side of the first cylinder member 1a. There is. In other words, the first and second
A non-pressurized drain gap 21 is opened to the atmosphere between the seal members 22 and 23 via the oil pipe 25 described below.
is provided. These seal members 22, 23
For example, a material with low sliding resistance made of synthetic resin or the like is used.

A leak oil outlet 24 is provided on the leak side of the first seal member 22. This leak oil outlet 24 communicates with the gap 21, so that oil leaking into the gap 21 can be taken out. The leak oil outlet 24 is led to the reservoir tank 14 of the hydraulic unit 12 via an oil feed pipe 25.

Also, there is a limit switch 3 on the side of the rod 3.
0,31 are provided. These limit switches 30, 31 are attached to a base 32 fixed to the rod end portion 3c, so that the relative position of the cylinder 1 with respect to the rod 3 can be detected.

The present embodiment configured as described above is used, for example, in a suspension system for an automobile. That is, when the rod 3 expands and contracts with respect to the cylinder 1, the piston portion 3b moves within the cylinder, causing oil to flow through the orifice 4 and exert a damping force. Further, fluctuations in the amount of oil in the rod 3 are absorbed by the free piston 6 moving up and down.

Furthermore, when the load applied to the vehicle body is large, the rod 3 moves in the direction of being pushed into the cylinder 1, and the free piston 6 is pushed up, causing the gas chamber 7
The high-pressure gas inside is compressed, and the free piston 6 stops at a position where the gas and oil pressures are balanced.
When the rod 3 is compressed in this way, one of the limit switches 30 is activated by the first member 1a of the cylinder.
When it is desired to keep the vehicle height constant, the directional control valve 15 is operated in response to the signal from the limit switch 30, and oil is injected into the cylinder 1 from the oil inlet/outlet 10.
By doing this, the rod 3 can be pushed up to a predetermined height.

On the contrary, when the load applied to the vehicle body is small, the rod 3 is extended and the other limit switch 31 is activated. Therefore, if you want to keep the vehicle height constant, operate the directional control valve 15 in the opposite direction to the above using the signal from the limit switch 31, and drain the oil in the cylinder 1 through the oil inlet/outlet 10 to keep the rod 3 at a predetermined position. can be lowered to a height of

According to the embodiment with the above configuration, the leak oil outlet 24 is provided on the leak side of the first seal member 22.
By providing this, oil leaking into the gap 21 can be returned to the reservoir tank 14, so even if oil leaks from the first sealing member 22, the pressure in the gap 21 can be prevented from increasing. Therefore, the sealing force of the second sealing member 23 can also be small. That is, these seal members 22,
By using a material with low sliding resistance and relatively small interference for 23, leakage of oil to the outside can be prevented and the sealing effect can be sufficiently exhibited.
Since the oil discharged from the leaked oil outlet 24 is returned to the reservoir tank 14, there is no substantial oil loss and a specified amount of oil can always be secured.

Note that if the amount of oil discharged from the leak oil outlet 24 is small, the reservoir tank 1
Instead of returning to 4, the oil may be stored in a drain or the like as waste oil.

Furthermore, the present invention can of course be applied to a vehicle height adjustment device using an actuator of a type that does not have a free piston 6. Furthermore, in carrying out the present invention, cylinders, rods,
It goes without saying that the specific configurations of the piston section, hydraulic unit, seal member, leaked oil outlet, etc. can be modified in various ways.

As described above, the present invention makes it possible to use a sealing member with low sliding resistance on the sliding part between the cylinder and the rod, so that the rod moves smoothly and improves the performance of the vehicle height adjustment device. I can do it.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a conventional actuator, and FIG. 2 is a longitudinal sectional view showing an embodiment of the present invention. 1... Cylinder, 3... Rod, 3b... Piston part, 4... Orifice, 12... Hydraulic unit, 14
... Reservoir tank, 21 ... Gap, 22 ... Seal member, 24 ... Leak oil outlet, 25 ... Oil feed pipe.

Claims (1)

[Claims] 1. A cylinder containing oil, a rod slidably inserted into the cylinder and equipped with a piston having an orifice, and a hydraulic unit capable of putting oil in and out of the cylinder. In the vehicle height adjustment device, a first seal member on the high pressure side is disposed in the sliding portion between the end of the rod and the inner surface of the cylinder in the cylinder, and a first seal member on the high pressure side is arranged in the sliding portion between the rod and the cylinder at the open end of the cylinder. A second seal member on the low pressure side is arranged on the moving part, that is, on the leakage side of the first seal member, and a non-pressurized drain gap opened to the atmosphere is provided between the first and second seal members. The vehicle height adjustment device further comprises a leak oil outlet in the cylinder that communicates with the non-pressurized drain gap. 2. The vehicle height adjustment device according to claim 1, wherein the leak oil outlet is connected to a reservoir tank of the hydraulic unit via an oil feed pipe.