JPH07224879A - Piston ring structure of hydraulic buffer - Google Patents

Abstract

PURPOSE:To improve sealing ability between a cylinder and a piston by a method wherein a resilient ring is arranged corresponding to the stepped part of the abutment of a piston ring. CONSTITUTION:Formation of a hydraulic buffer is such that a main piston 12 having oil flow passages 17 and 18 and a dumping valve is slidably arranged in a cylinder 11 filled with working oil and a piston ring 24A is disposed to the outer periphery of the main piston 12. A piston ring has an abutment formed in an arbitrary position in a peripheral direction, a plurality of O-rings 36 are located between the main piston and the piston ring, and the O-ring is arranged in a position corresponding to the stepped part of the abutment of the piston ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring structure for a hydraulic shock absorber.

[0002]

2. Description of the Related Art In a hydraulic shock absorber applied to an automobile or the like, a piston is slidably disposed in a cylinder filled with hydraulic oil, a flow path is formed in the piston, and the flow path is A damping valve that can be closed is installed on the piston, and a piston ring is arranged on the outer circumference of the piston. The inside of the cylinder is divided into two chambers by the piston and the piston ring. As the piston slides, a damping force is generated due to the flow resistance when the working oil flowing from one chamber to the other chamber via the flow path flexibly deforms the damping valve.

The seal between the piston and the cylinder is implemented by a piston ring as in the inventions disclosed in Japanese Utility Model Laid-Open No. 3-44239 and Japanese Utility Model Laid-Open No. 1-75638. Among them, in the latter device (first conventional example), the piston ring is divided into two in the axial direction, and the joints (abutments) of the respective divided rings are arranged so as not to coincide with each other. The hydraulic oil is prevented from leaking.

Another conventional example is one in which an O-ring is arranged between the outer circumference of the piston and the piston ring, and one step is formed at the joint (joint) of the piston ring. (Second conventional example). The O-ring is arranged corresponding to the step portion of the seam. The O-ring makes the piston and the piston ring liquid-tight, and blocks the flow of the hydraulic oil through the joint of the piston ring to improve the sealing performance.

[0005]

However, in the above-mentioned first conventional example, even if the seams of the two split rings are arranged so as to be inconsistent with each other, this alone is not sufficient for the sealing property at the seams. I can't say.

In the second conventional example, since the piston ring is supported on the outer circumference of the piston by a single O-ring, the stability of the piston ring is poor, especially when the axial length of the piston ring is long. The surface pressure between the piston ring and the cylinder varies, and the sealing property between the piston ring and the cylinder deteriorates.

The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a piston ring structure of a hydraulic shock absorber capable of improving the sealing performance between a cylinder and a piston. .

[0008]

According to the present invention, a piston provided with a flow path and a damping valve is slidably arranged in a cylinder filled with hydraulic oil, and a piston ring is provided on the outer circumference of the piston. In the hydraulic shock absorber provided, the piston ring has an abutment formed at an arbitrary position in the circumferential direction, the abutment includes a plurality of step portions in the axial direction of the piston ring, and the piston and the A plurality of elastic rings are interposed between the piston ring and the piston rings, and these elastic rings are arranged so as to correspond to the step portion at the joint of the piston ring.

[0009]

Therefore, according to the piston ring structure of the hydraulic shock absorber according to the present invention, a plurality of step portions are formed in the piston ring abutment in the axial direction of the piston ring. The flow of hydraulic oil that has entered can be stopped in stages. Further, since each of the plurality of elastic rings interposed between the piston outer circumference and the piston ring is arranged corresponding to the plurality of stepped portions of the abutment in the piston ring, by these elastic rings,
The piston and the piston ring can be configured to be liquid-tight, and the step of blocking the flow of hydraulic oil by the step can be promoted. For these reasons, both the sealability between the piston and the piston ring and the sealability of the piston ring can be improved.

Further, since the piston ring is supported by the piston by a plurality of elastic rings arranged in the axial direction, the piston ring can be stably supported with respect to the piston even if the axial length of the piston ring becomes long. . Therefore, it is possible to reduce the variation in the surface pressure between the piston ring and the cylinder, and improve the sealing performance between the piston ring and the cylinder.

As described above, since the sealability between the piston and the piston ring, the sealability of the piston ring, and the sealability between the piston ring and the cylinder can be improved, the sealability between the piston and the cylinder is improved. Can be suitably improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a hydraulic shock absorber showing an embodiment of the piston ring structure of the hydraulic shock absorber according to the present invention. FIG. 2 is a partially enlarged sectional view around the piston ring in FIG. FIG. 3 is a view on arrow III in FIG. Figure 4 (A)
FIG. 4 is a front view showing the piston ring of FIG.
4B is a cross-sectional view taken along the line IVB-IVB in FIG. 4A, and FIG. 4C is a view taken along the line IVC in FIG. 4A. FIG. 5 (A) is a front view showing the O-ring of FIG.
5B is a sectional view taken along the line VB-VB in FIG. 5A, and FIG. 5C is an enlarged view of a VC portion in FIG. 5B.
FIG. 6 is a graph showing the load-displacement characteristic of the disc spring in the hydraulic shock absorber of FIG.

The hydraulic shock absorber 10 shown in FIG.
A main piston 12 and a free piston 13 are slidably arranged in the cylinder 1, and an opening of a cylinder 11 is closed by a cylinder cap 14. Main piston 1
The inside of the cylinder 11 is divided into the A chamber 15A and the B chamber 15B by 2, and the C chamber 15C is divided into the B chamber 15B by the free piston 13. A chamber 15A and a B chamber 15B are filled with hydraulic oil, and a C chamber 15C is filled with a gas such as nitrogen gas.

A piston rod 16 is penetrated through the central portion of the main piston 12, and an expansion-side oil passage 17 and a contraction-side oil passage 18 are alternately penetrated and formed around the piston rod 16. Further, an expansion-side damping valve 19 capable of closing the expansion-side oil flow path 17 is installed on one side surface of the main piston 12, and a compression-side damping valve 20 capable of closing the compression-side oil flow path 18 is installed on the other side surface thereof. It

A ring 21 is fitted on the piston rod 16, and the valve retainer 22 is supported by the ring 21. In addition, the nut 23 is attached to the end of the piston rod 16.
Are screwed together. The nut 23 and the valve retainer 22
Thus, the main piston 12, the expansion side damping valve 19, and the compression side damping valve 20 are integrally fixed to the piston rod 16, and at the same time, the expansion side damping valve 19 and the compression side damping valve 2
Zero is flexibly attached to each side surface of the main piston 12.

In the contraction process of the hydraulic shock absorber 10, as shown by the broken line arrow M, the hydraulic oil in the B chamber 15B passes through the contraction side oil flow path 18 and flexibly deforms the contraction side damping valve 20. It flows into the chamber 15A. Further, in the extension process of the hydraulic shock absorber 10, as shown by the solid arrow N, the hydraulic oil in the A chamber 15A passes through the inside of the extension side passage 17, and the extension side damping valve 19 is flexibly deformed to the B chamber 15B. Inflow. A force by which the hydraulic oil flexibly deforms the expansion side damping valve 19 and the compression side damping valve 20 is generated as an expansion side damping force and a contraction side damping force. This damping force is proportional to the bending deformation force of the valves 19 and 20 due to the hydraulic oil.

Piston rings 24A (described later) and 24B are fitted on the outer peripheral portion of the main piston 12 and the outer peripheral portion of the free piston 13 to facilitate sliding of the pistons 12 and 13. Further, the cylinder cap 14 has
Guide bush 2 for guiding sliding of piston rod 16
5 is fitted.

On the cylinder cap 14, an oil seal 26 is fitted on the sliding portion with the piston rod 16, an O-ring 27 is fitted on the fitting portion with the cylinder 11, and the O-ring 27 is also fitted on the outer circumference of the free piston 13. It is installed. With the oil seal 26 and the O-ring 27, the chamber A 1
The 5A and B chambers 15B are liquid-tight.

The free piston 13 is a piston rod 16 which penetrates into the chamber A 15A when the hydraulic shock absorber 10 contracts.
It has the function of absorbing the hydraulic oil equivalent to the invading volume. Also,
Reference numeral 28 is an eye for mounting the hydraulic shock absorber 10 on the axle side of the vehicle.

The adjusting rod 2 is provided in the piston rod 16.
9 is provided so as to penetrate therethrough. The adjusting rod 29 is fitted to the piston rod 16 by an adjusting screw 30, and is provided so as to be movable relative to the piston rod 16 in the axial direction S of the piston rod 16. Also, the adjusting rod 2
A pin 31 is fitted to the tip of the spring 9, and the spring retainer 32 is supported by the pin 31. This spring retainer 32
One or a plurality of disc springs 34 (three in this embodiment) are provided between the cage 33 and the cage 33. The cage 33 has a cylindrical shape, one end of which is in contact with the rear surface of the extension damping valve 19 and the disc spring 34 is locked by the step 35 of the other end.

When an operating pin (not shown) is inserted into the pin hole 36 at the other end of the adjusting rod 29 and the adjusting rod 29 is rotated, the adjusting rod 29 moves in the axial direction S with respect to the piston rod 16. To do. As a result, the disc spring 34 is displaced in the axial direction (the same direction as the axial direction S of the piston rod 16), and the biasing force applied from the disc spring 34 to the rear surface of the extension side damping valve 19 via the cage 33 is changed. The flexural deformation amount of the expansion side damping valve 19 due to the hydraulic oil that has passed through the expansion side oil flow path 17 varies. If the biasing force of the disc spring 34 is increased, it becomes difficult for the expansion side damping valve 19 to be flexibly deformed by the hydraulic oil, and the expansion side damping force of the hydraulic shock absorber 10 increases. Further, if the biasing force of the disc spring 34 is reduced, the expansion side damping valve 19 is easily deformed flexibly by the hydraulic oil, and the expansion side damping force of the hydraulic shock absorber 10 is reduced.

As shown in FIG. 6, the disc spring 34 has a proportional load characteristic with respect to the displacement. Therefore, if the disc spring 34 is displaced by a constant amount α by the adjusting rod 29, the load of the disc spring 34 is increased. Increase or decrease a predetermined amount β. Thereby, the extension side damping force of the hydraulic shock absorber 10 by the extension side damping valve 19 can be increased / decreased in proportion to the movement amount of the adjusting rod 29, and the extension side damping force of the hydraulic shock absorber 10 can be easily and reliably obtained. It can be adjusted to the desired value.

Further, the urging force to the extension side damping valve 19 is
Since the disc spring 34 is provided with an axial length shorter than that of the coil spring, the hydraulic shock absorber 10 does not become large even if the disc spring 34 is arranged on the back side of the expansion side damping valve 19, and the compact hydraulic shock absorber is provided. 10 can be designed.

In the above embodiment, the case where the damping force by the expansion side damping valve 19 is changed by using the disc spring 34, the cage 33 and the pin 31 has been described.
The damping force of the compression-side damping valve 20 may be adjustable.

Now, as described above, the piston ring 24
A is fitted on the outer peripheral portion of the main piston 12, and an O-ring 36 as an elastic ring is interposed between the piston ring 24A and the main piston 12 as shown in FIG. That is, a piston ring mounting groove 37 is formed on the outer peripheral portion of the main piston 12 over the entire circumference thereof, and the piston ring 24A is fitted into the piston ring mounting groove 37. Also, the piston ring mounting groove 37
In the axial direction of the main piston 12 (piston ring 2
A plurality of, for example, two O-ring mounting grooves 38 are formed in parallel in the same direction as the axial direction of 4A), and the O-rings 36 are fitted into these O-ring mounting grooves 38.

As shown in FIG. 4, the piston ring 24A has a joint 39 (joint) formed at an arbitrary position in the circumferential direction so that the piston ring 24A can be expanded / contracted. As shown in FIG. 3, a plurality of the joints 39 are arranged in the axial direction of the piston ring 24A,
For example, two step portions 40 are provided. Due to this step portion 40, a plurality of abutments 39 are provided in the axial direction of the piston ring 24A,
For example, it is divided into three. Therefore, the flow of hydraulic oil that has entered the joint 39 is blocked by the step 40.

The O-ring 36 is made of an elastic material such as rubber or synthetic resin. As shown in FIGS. 2 and 5, the O-ring 36 has a D-shaped cross section, and has a flat surface portion 41 facing outward and a circular arc surface portion 42 facing inward. This O
The arcuate surface portion 42 of the ring 36 is the O of the main piston 12.
The piston ring 24 is fitted in the ring mounting groove 38, and the flat surface portion 41 abuts on the inner peripheral surface of the piston ring 24A.
A is supported by the main piston 12 via the O-ring 36. At this time, a clearance 44 is provided between the piston ring mounting groove 37 of the main piston 12 and the inner peripheral surface of the piston ring 24A.

Also, as shown in FIGS. 2 and 3, the O-ring 36 has the flat surface portion 41 corresponding to the step portion 40 in the abutment 39 of the piston ring 24A when the O-ring 36 is inserted into the O-ring mounting groove 38. Makes surface contact with the position. As a result, the O-ring 36 liquid-tightens the step 40 of the abutment 39, and the step 40
The function of damming the hydraulic oil in the joint 39 is promoted.

Further, a peripheral groove 43 is formed on the outer peripheral portion of the piston ring 24A at a substantially central position in the axial direction of the piston ring 24A over the entire circumference. Piston ring 2
The hydraulic oil that has entered between the 4A and the cylinder 11 flows into the circumferential groove 43, the flow velocity is reduced, and the hydraulic oil can be retained in the circumferential groove 43.

According to the above embodiment, the main piston 12
Since a plurality of O-rings 36 are provided between the piston ring mounting groove 37 and the piston ring 24A, the O-rings 36 can form a liquid-tight space between the main piston 12 and the piston ring 24A. Therefore, the sealing property between the main piston 12 and the piston ring 24A is improved.

Further, since a plurality of step portions 40 are formed in the joint port 39 of the piston ring 24A in the axial direction of the piston ring 24A, the step portion 40 blocks the flow of the hydraulic oil entering the joint port 39. be able to. Furthermore, since each of the plurality of elastic rings 36 is arranged corresponding to the plurality of step portions 40 of the joint 39 in the piston ring 24A, these O-rings 36
The step of blocking the flow of hydraulic oil by the step can be promoted, and the sealability of the piston ring 24A can be improved.

Further, since the piston ring 24A is supported by the main piston 12 by a plurality of O-rings 36 arranged in the axial direction, even if the axial length of the piston ring 24A becomes long, the piston ring 24A becomes a piston. On the other hand, it can be stably supported. Therefore, it is possible to reduce the variation in the surface pressure between the piston ring 24A and the cylinder 11,
The sealability between the piston ring 24A and the cylinder 11 can be improved.

As described above, the sealing property between the main piston 12 and the piston ring 24A, the piston ring 24A
Sealability of the piston ring 24A and the cylinder 11
Since the sealing performance between the main piston 12 and the cylinder 11 can be improved, the sealing performance between the main piston 12 and the cylinder 11 can be improved.

Further, since the O-ring 36 is formed in a D-shape in cross section and the flat portion 41 is brought into contact with the piston ring 24A, the O-ring 36 and the piston ring 24A are in surface contact with each other. Therefore, the O-ring 36 can further improve the hydraulic oil damming function of the step 40 of the abutment 39 in the piston ring 24A.

Further, the circumferential groove 4 is formed on the outer circumference of the piston ring 36.
3 is formed, the hydraulic fluid that has entered between the piston ring 24A and the cylinder 11 in the sliding contact state between the piston ring 24A and the cylinder 11 flows into the circumferential groove 43, and the flow velocity is reduced. Collect. As a result, the sealing property between the cylinder 11 and the piston ring 24A can be further improved.

Further, since the O-ring 36 is interposed between the main piston 12 and the piston ring 24A, a force perpendicular to the axial direction acts on the piston rod 16 and the main piston 12 and the cylinder 11 are displaced from each other. Even if
The O-ring 36 can be expanded and contracted to absorb the above deviation. Therefore, the sealing property between the cylinder 11 and the main piston 12 can be favorably maintained.

In the above embodiment, the step portion 40 of the joint 39 is provided.
The number of O-rings 36 is two and the number of O-rings 36 is two.
There may be a plurality of rings 36 such as four.

[0038]

As described above, according to the piston ring structure of the hydraulic shock absorber according to the present invention, the sealing property between the cylinder and the piston can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic shock absorber showing an embodiment of a piston ring structure of the hydraulic shock absorber according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view around the piston ring of FIG.

FIG. 3 is a view on arrow III in FIG.

4B is a cross-sectional view taken along line IVB-IVB of FIG. 4A, and FIG. 4C is a IVC arrow view of FIG. 4A.

5 (A) is a front view showing the O-ring of FIG. 2, and FIG. 5 (B) is a sectional view taken along line VB-VB of FIG. 5 (A). FIG. 5C is an enlarged view of the VC portion of FIG.

6 is a graph showing a load-displacement characteristic of a disc spring in the hydraulic shock absorber of FIG.

[Explanation of symbols]

 10 Hydraulic Shock Absorber 11 Cylinder 12 Main Piston 15A A Chamber 15B B Chamber 17 Extension Side Oil Flow Path 19 Extension Side Damping Valve 24A Piston Ring 36 O Ring 39 Piston Ring Abutment 40 Abutment Step 41 O-Ring Flat 43 Piston Ring groove

Claims (3)

[Claims] 1. A hydraulic shock absorber in which a piston provided with a flow path and a damping valve is slidably arranged in a cylinder filled with hydraulic oil, and a piston ring is arranged on the outer circumference of the piston. So, the piston ring is
An abutment is formed at an arbitrary position in the circumferential direction, the abutment includes a plurality of stepped portions in the axial direction of the piston ring, and a plurality of elastic rings are interposed between the piston and the piston ring. The elastic ring is arranged corresponding to the stepped portion in the joint of the piston ring. 2. The piston ring structure for a hydraulic shock absorber according to claim 1, wherein the elastic ring is formed in a D-shape in cross section, and the flat portion thereof is disposed in contact with the piston ring. 3. The piston ring structure for a hydraulic shock absorber according to claim 1, wherein the piston ring has a circumferential groove formed on an outer circumference thereof that is in sliding contact with the cylinder.