JPH0716484Y2 - Suspension device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is provided, for example, between an axle side and a vehicle body side of a vehicle, and supplies and discharges high-pressure oil liquid (pressure oil) from the outside to the vehicle. The present invention relates to a suspension device adapted to perform high adjustment and the like.

[Conventional technology]

FIG. 6 shows a hydraulic circuit of a suspension device according to the prior art.

In the figure, reference numeral 1 denotes a hydraulic pump driven by an engine or the like. The hydraulic pump 1 sucks oil liquid in a tank 2 through a filter 3, and a supply pipe 6 provided with a check valve 4 and a main accumulator 5 on the way. This oil liquid (pressure oil) is discharged into the inside. Then, the accumulator 5 temporarily stores the pressure oil from the hydraulic pump 1,
This pressure oil is supplied when adjusting the vehicle height.

Reference numeral 7 denotes a directional switching valve arranged between the supply pipe 6 and the supply / discharge pipe 8. The switching valve 7 is constituted by a 3-port 3-position electromagnetic directional switching valve or the like, and is normally in the neutral position (a). ), And is switched from the neutral position (a) to the switching positions (b) and (c) by energization from the outside. Then, when the switching valve 7 is switched to the switching position (b), the pressure oil from the hydraulic pump 1 is supplied from the supply pipe 6 to the suspension device A side described later through the supply / discharge pipe 8 to switch to the switching position (c). ), The pressure oil in the suspension device A is discharged from the supply / discharge pipe 8 to the tank 2 side through the return pipe 9.

Next, the suspension device A will be described in detail with reference to FIG. The suspension device A is provided on each of the front and rear wheels of the vehicle, but only one is shown in the drawing.

Each suspension device A includes a cylinder 10 and the cylinder.
It is slidably inserted into the inside of the cylinder 10 and the upper and lower 2
Pistons 11 defined by two oil chambers 10A, 10B, a piston rod 12 having a lower end fixed to the piston 11 and an upper end protruding above the cylinder 10, and a piston rod 12 provided at the upper end of the piston rod 12 A connecting member 14 for connecting the pipe 8 to a communication hole 13 formed at the center of the piston rod 12 is provided.

The pressure oil supplied from the supply / discharge pipe 8 is connected through the connection member 14 to the communication hole.
The oil is sent to the lower oil chamber 10B through 13 and is supplied to the oil chamber 10A through the small holes 15 formed in the piston 11. In addition, pressure oil is supplied from the communication hole 13 through the damping force generation mechanism.
The gas is supplied to the accumulator 17 for the gas spring, which is provided integrally with the piston rod 12 via 16. The accumulator 17 has an intermediate free piston 17A.
Thus, the upper oil storage chamber 17B and the lower gas chamber 17C are defined, and the accumulator 17 compensates the expansion and contraction of the piston rod 12.

Thus, the suspension device A is, for example, the cylinder 10
The lower end of the piston rod 12 is attached to the axle side of the vehicle, and the protruding end side of the piston rod 12 is attached to the vehicle body side. The damping force generating mechanism 16 damps the vibration applied to the vehicle.

That is, when the piston rod 12 expands and contracts from the cylinder 10 due to the vibration, the accumulator 17 causes the pressure oil in the oil storage chamber 17B to damp the pressure oil in the oil storage chamber 17B by the gas pressure in the gas chamber 17C.
When the pressure oil flows in and out of the oil chamber 10B via the, and the pressure oil flows through the damping force generating mechanism 16, a damping force for vibration damping is generated by its throttling action.

Further, when the vehicle height becomes low due to an increase in the load weight of the vehicle or the like, the pressure from the hydraulic pump 1 is changed by switching the switching valve 7 shown in FIG. 6 from the neutral position (a) to the switching position (b). Oil can be supplied to the oil chamber 10B and the oil storage chamber 17B of the accumulator 17 through the connecting member 14 and the communication hole 13 to extend the piston rod 12 and adjust the vehicle height to be high. On the other hand, by switching the switching valve 7 to the switching position (C), the pressure oil in the oil chamber 10B and the oil storage chamber 17B is communicated with the communication hole 1
3, the connecting member 14, the supply / discharge pipe 8 and the return pipe 9 are discharged into the tank 2, and the piston rod 12 is contracted so that the vehicle height can be adjusted to be low.

The above-described structure and operation are related to the main part of the conventional suspension device A. Next, the drain system of the oil liquid and the like will be described.

Here, the cylinder 10 is composed of an outer cylinder 18 and an inner cylinder 19 arranged coaxially with the outer cylinder 18, the lower ends of the outer cylinder 18 and the inner cylinder 19 are closed by a bottom cap 20, and the upper end is at the center. A piston rod 12 is slidably penetrated through the rod guide 21, and a drain chamber 22 is formed between the outer cylinder 18 and the inner cylinder 19.

As clearly shown in FIG. 8, the upper end portion of the inner cylinder 19 slightly plastic-deforms the metal seal 23 interposed between the lower surface of the large diameter portion 21A of the rod guide 21 and the rod guide 21.
The large diameter portion 21A of 21 is fitted and fixed to a small diameter portion 21B that is continuously provided in the center of the lower surface. A rod seal such as an O-ring 24 and a synthetic resin ring 25 such as a fluororesin (Teflon) is fitted into the insertion portion of the piston rod 12 of the rod guide 21, and the upper portion thereof is closed by a holding plate 26. Also,
An upper cap 27 is fitted inside the outer cylinder 18 above the pressing plate 26, and a dust seal 28 that is slidably contacted with the outer circumference of the piston rod 12 is provided inside the upper cap 27.

Here, the oil liquid leaking above the holding plate 26 through the gap between the piston rod 12 rod guide 21 and the synthetic resin ring 25 from the oil chamber 10A above the cylinder 10 is separated between the holding plate 26 and the upper cap 27. It is temporarily stored in the drain chamber 22 through the gap between them, and the drain grooves 29, 30 formed so as to be continuous with the outer periphery of the pressing plate 26 and the outer periphery of the rod guide 21,
From there, as shown in FIGS. 6 and 7, the drain chamber 22 and the return pipe 9 are returned to the tank 2 through the drain pipe 31 and the return pipe 9 each end of which is connected. . In addition, 32 is a connection point between the return pipe 9 and the drain pipe 31,
The reference numeral 33 indicates a bump rubber receiver provided on the upper end of the upper cap 27.

[Problems to be solved by the device]

By the way, in the above-mentioned conventional technique, when the switching valve 7 is switched to the switching position (C) and the pressure oil in the suspension device A is returned to the tank 2 side via the supply / discharge pipe 8, the supply / discharge pipe 8 is returned. The pressure in the pipe 9 may be quite high. Therefore, the pressure oil in the return pipe 9 flows back into the drain chamber 22 via the drain pipe 31, and the drain chamber 22 causes the drain grooves 30 and 29, the space between the holding plate 26 and the upper cap 27, and the holding plate 26. The pressure up to the gap between the dust seal 28 and the dust seal 28 may increase.

On the other hand, since the dust seal 28 is merely provided for the purpose of dust prevention, the drain chamber 22 as described above is provided.
There is no opposing force against the reverse flow of the oil liquid from the cylinder 10, the oil liquid leaks to the outside through the dust seal 28, leading to the loss of the oil liquid, or dust or the like adheres to the leaked oil liquid, and the cylinder 10
There is a problem such as soiling the upper part of. Also, the dust seal 28
The pressure of the drain oil liquid is applied to the dust seal 28, and the friction between the dust seal 28 and the piston rod 12 becomes large, which may deteriorate the riding comfort of the vehicle and may further damage or drop the dust seal 28.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to remove a return pipe from a return pipe when a switching valve is switched from a suspension device side to a direction in which pressure oil is returned to a tank side. It is an object of the present invention to provide a suspension device capable of preventing the drain oil liquid from leaking from the dust seal and preventing damage to the dust seal itself even when a backflow of pressure oil occurs to the drain chamber side.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention provides an outer cylinder, an inner cylinder arranged in the outer cylinder, and a slidable fit in the inner cylinder, and an oil chamber in the inner cylinder. A defined piston, a piston rod having one end fixed to the piston and the other end protruding to the outside of the outer cylinder via a rod guide, a rod seal provided on the rod guide, and a dust seal, and the piston rod. A switch valve for selectively connecting the oil chamber to a supply pipe connected to the hydraulic pump and a return pipe connected to the tank for supplying and discharging pressure oil to and from the oil chamber in the inner cylinder via the inner cylinder and the inner cylinder. A drain chamber that is formed between the oil chamber in the inner cylinder and collects the oil liquid that has leaked from the oil chamber through the rod seal, and the drain chamber is connected to the return pipe to remove the oil liquid in the drain chamber. The drain pipe that discharges to the tank side and expansion and contraction of the piston rod are supplemented. It applied to the suspension system consisting of accumulator.

The feature of the configuration adopted by the present invention is that pressure oil flows from the return pipe side toward the dust seal side at an appropriate position between the connection point of the drain pipe to the return pipe and the dust seal. A check valve for blocking is provided, and the check valve is configured to allow the oil liquid leaked from the oil chamber in the inner cylinder via the rod seal to flow toward the drain chamber and the drain pipe side. It is in.

[Action]

With the above configuration, when the oil liquid leaks from the oil chamber in the inner cylinder through the rod seal, the oil liquid can be released toward the drain chamber and the drain pipe side through the check valve. With this, it is possible to reliably prevent the pressure in the drain chamber from rising. Further, when the oil chamber in the inner cylinder is connected to the return pipe connected to the tank by the switching valve, and when the pressure oil in the oil chamber is discharged to the return pipe side, the pressure oil in the return pipe passes through the drain pipe. Even if backflow occurs to the drain chamber side, the backflow at this time can be blocked by the check valve.Therefore, pressure oil in the return pipe will not flow back toward the dust seal side, and it is possible to reliably prevent high pressure from acting on the dust seal. it can.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. In the following embodiments, the same components as those of the prior art shown in FIG. 6 to FIG. 8 described above are designated by the same reference numerals and the description thereof will be omitted.

Thus, FIG. 1 shows a first embodiment of the present invention.

In the figure, 41 indicates a check valve provided in the middle of the drain pipe 31, and the check valve 41 allows the oil liquid to flow in the direction of the return pipe 9 and prevents the oil liquid from flowing in the opposite direction. It is like this.

The present embodiment has the configuration as described above, and the basic operation thereof is not different from that of the prior art.

However, in this embodiment, the check valve is provided in the middle of the drain pipe 31.
Since 41 is provided, the switching valve 7 is switched to the switching position (C),
When the pressure oil in the oil chamber 10B of the cylinder 10 is discharged to the tank 2 side via the supply / discharge pipe 8 and the return pipe 9, the return pipe 9
Even if the pressure of the oil liquid inside becomes relatively large, the flow of the oil liquid toward the drain chamber 22 is blocked by the check valve 41, and the pressure oil inside the return pipe 9 passes through the drain pipe 31 to the drain chamber 22. There will be no backflow.

Therefore, as in the prior art, the oil liquid flows back from the drain pipe 31 toward the dust seal 28 through the drain chamber 22 and the drain grooves 30 and 29, and the pressure acts on the dust seal 28, so that the dust seal 28 and the piston rod 12 are The friction of
It is possible to prevent the ride comfort of the vehicle from being deteriorated, to prevent the dust seal 28 from being damaged or to fall off, and to solve the problem that the drain oil liquid leaks from the dust seal 28 to the outside.

Further, when the switching valve 7 is switched to the neutral position (a) or the switching position (b), the return pipe 9 is shut off from the supply / discharge pipe 8 and the supply pipe 6, so that the inside of the return pipe 9 is the tank 2 The same pressure as the inside is obtained, and the drain oil liquid accumulated in the drain chamber 22 can be automatically discharged to the tank 2 through the check valve 41, the drain pipe 31, and the return pipe 9, and so on.

Next, FIG. 2 and FIG. 3 show a second embodiment of the present invention. The feature of this embodiment is that a lip seal 51 as a check valve is provided at the upper end of the drain chamber 22. It is in. Here, as shown in FIG. 3, the lip seal 51 includes a core metal 52 in which an annular collar portion 52B is continuously provided on an upper end of a cylindrical base portion 52A,
An elastic body made of rubber or soft synthetic resin or the like integrally formed to cover the flange portion 52B of the cored bar 52 and having bifurcated lip portions 53A and 53B inclined outwardly and inwardly on the outer peripheral side lower portion. It is composed of 53 and. And the core metal 52
The base portion 52A is fitted to an intermediate step portion 21C provided between the large diameter portion 21A and the small diameter portion 21B of the rod guide 21, and is fixed to the rod guide 21 together with the metal seal 23. Further, the lip portion 53A of the elastic body 53 elastically contacts the inner peripheral surface of the outer cylinder 18 to allow the oil liquid to flow from the drain groove 30 toward the drain chamber 22, but from the drain chamber 22 toward the drain groove 30. It is designed to block the flow of oil liquid. In this embodiment, the metal seal 23 is sandwiched between the lower surface of the intermediate step portion 21C and the upper end of the inner cylinder 19 so as to also prevent the lip seal 51, which is a check valve, from coming off.

Thus, also in the present embodiment configured as described above, the lip seal 51 acts in the same manner as the check valve 41 in the first embodiment and exhibits the same effect. That is, when the pressure in the drain chamber 22 rises due to the reverse flow of the oil liquid from the return pipe 9 to the drain pipe 31, the lip portion 53A of the elastic body 53 causes the inner circumference of the outer cylinder 18 by the pressure in the drain chamber 22. It is strongly pressed against the surface and prevents the oil liquid in the drain chamber 22 from flowing back to the dust seal 28 side through the drain grooves 30 and 29.

Further, when the pressure in the return pipe 9 becomes the tank pressure state, the pressure does not act on the lip portion 53A of the elastic body 53 from the drain chamber 22 side, and the drain oil liquid leaked to the drain groove 30 is It can easily pass between the lip portion 53A and the inner peripheral surface of the outer cylinder 18 and flow down into the drain chamber 22.

Next, FIGS. 4 and 5 show a third embodiment of the present invention, which is characterized by a lip seal 61 similar to the lip seal 51 used in the second embodiment as a check valve. Used,
This lip seal 61 has the same function as the metal seal 23 in the second embodiment, so that the metal seal 23 can be omitted. Where the lip seal 61
Is a cylindrical cored bar 62 formed of the same material as the metal seal 23 and having a substantially T-shaped cross section, a cylindrical base part 62A of the cored bar 62, and an outward flange part 62B continuous with the upper end thereof. And an elastic body 63 having a lip portion 63A which is integrally molded so as to cover the outer periphery thereof and which is inclined and protrudes outward. Then, the inward flange portion 62C continuously provided at the upper end of the base portion 62A in the core metal 62 is sandwiched between the lower surface of the large diameter portion 21A of the rod guide 21 and the upper end of the inner cylinder 19, thereby The upper surfaces of the outward flange portion 62B and the inward flange portion 62C and the upper end surface of the elastic body 63 are pressed against the lower surface of the large diameter portion 21A of the rod guide 21, and the tip end of the lip portion 63A of the elastic body 63 is the outer cylinder. Make sure that the lip seal 61
Is provided at the upper end of the drain chamber 22.

Thus, in this embodiment configured as described above, the same effect as that of the second embodiment can be obtained, but in this embodiment, the metal seal 23 used in the prior art is omitted. There is an advantage that you can.

The present invention is not limited to the above three embodiments, and various modifications can be made without changing the gist of the invention.

For example, the check valve for backflow prevention used in the first embodiment
41 between the drain pipe 31 and the outer cylinder 18 of the cylinder 10.
It may be provided on the side.

[Effect of device]

As described above in detail, according to the present invention, it is possible to prevent pressure oil from flowing from the return pipe side toward the dust seal side at a proper position between the connection point of the drain pipe to the return pipe and the dust seal. A check valve for
Since the oil liquid leaked from the oil chamber in the inner cylinder through the rod seal was allowed to flow toward the drain chamber and the drain pipe side, the oil chamber in the inner cylinder was returned to the return pipe by the switching valve. When connecting and discharging the pressure oil to the return pipe side, it is possible to prevent the pressure oil in the return pipe from flowing back to the drain chamber and the dust seal side through the drain pipe. The reverse flow of the oil liquid from the piping exerts pressure on the dust seal, which increases the friction between the dust seal and the piston rod, resulting in poor riding comfort, damage or drop of the dust seal, and drain oil liquid leaking from the dust seal to the outside. As a result, various effects such as loss of oil liquid and pollution of the outside of the device can be achieved.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a suspension device showing a first embodiment of the present invention, FIGS. 2 and 3 show a second embodiment, and FIG. 2 is a longitudinal sectional view of a main part of the suspension device. FIG. 3 is a partially enlarged view of FIG. 2, FIGS. 4 and 5 show a third embodiment, FIG. 4 is a longitudinal sectional view of an essential part similar to FIG. 2, and FIG. 6 is a partially enlarged view in FIG. 4, FIGS. 6 to 8 show a prior art, FIG. 6 is a hydraulic circuit diagram of a suspension device, FIG. 7 is a longitudinal sectional view of a main part of the suspension device,
FIG. 8 is a partially enlarged view of FIG. 1 ... hydraulic pump, 2 ... tank, 6 ... supply piping, 7
...... Switching valve, 8 ...... Supply and discharge pipe, 9 ...... Return pipe, 10 ...... Cylinder, 10A, 10B ...... Oil chamber, 11 ...... Piston, 12 ...... Piston rod, 13 ...... Communication hole, 16 ... ... Damping force generation mechanism,
17 …… Accumulator, 18 …… Outer cylinder, 19 …… Inner cylinder, 21…
… Rod guide, 22 …… Drain chamber, 23 …… Metal seal,
24 …… O ring (rod seal), 25 …… Synthetic resin ring (rod seal), 28 …… Dust seal, 29,30 ……
Drain groove, 31 …… Drain piping, 41 …… Check valve, 51,6
1 …… Lip seal (check valve), 52,62 …… Core bar, 5
3,63 ... Elastic body.

Claims (1)

[Scope of utility model registration request] 1. An outer cylinder, an inner cylinder arranged in the outer cylinder, a piston slidably fitted in the inner cylinder and defining an oil chamber in the inner cylinder, and one end thereof. One side is fixed to the piston, the other end side is a rod guide, a rod seal provided on the rod guide, and a piston rod protruding outside the outer cylinder via a dust seal; and a piston rod inside the inner cylinder via the piston rod. A switching valve that selectively connects the oil chamber to a supply pipe connected to the hydraulic pump and a return pipe connected to the tank for supplying and discharging the pressure oil to the oil chamber, and is formed between the outer cylinder and the inner cylinder. A drain chamber for storing the oil liquid leaked from the oil chamber in the inner cylinder through the rod seal, and a drain pipe for connecting the drain chamber to the return pipe and discharging the oil liquid in the drain chamber to the tank side And an accumulator that compensates the expansion and contraction of the piston rod. In that the suspension device,
At a suitable place between the connection point to the return pipe of the drain pipe and the dust seal, a check valve for preventing pressure oil from flowing from the return pipe side toward the dust seal side is provided, and the check valve is A suspension device configured to allow an oil liquid leaking from an oil chamber in the inner cylinder via the rod seal to flow toward the drain chamber and the drain pipe side.