JPH10103512A - Piston structure of hydraulic damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a piston to get rid of work on machining piston ring attaching grooves thereon and also to facilitate attachment of piston rings to the piston. SOLUTION: In this piston structure, a flow passage is formed by being guided to penetrate in the axial direction of a piston 11 making sliding motion in a cylinder 12 and a piston ring 13 is attached to the outer periphery of the piston. In such a case, the piston is constructed by axial connection of the first piston body 15 and the second piston body 16, respective recessed parts 29, 30 are formed on the outer peripheries facing to the connection surface 23 of the first piston body and the connection surface 24 of the second piston body, a projection part 33 is formed on the inner periphery of the piston ring and by axial sandwiching of the projecting part of the piston ring by means of the recessed parts of the mutually connected first and second piston bodies, the piston rings are attached to the outer periphery of the piston.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston structure of a hydraulic shock absorber, and more particularly to a piston structure of a hydraulic shock absorber in which a structure for attaching a piston ring to a piston is improved.

[0002]

2. Description of the Related Art In a hydraulic shock absorber, a piston ring which is slid in a cylinder is provided with a piston ring on the outer periphery of the piston in order to improve sealing, wear resistance and slidability.

[0003] In the piston structure described in Japanese Utility Model Laid-Open No. 59-32742, a belt-shaped piston ring is wound around the outer periphery of a piston (first prior art).

In the piston structure disclosed in Japanese Utility Model Application Laid-Open No. 60-118037, a ring-shaped piston ring is fitted around the outer periphery of the piston, and then a holding member is screwed onto the piston to hold the piston. Is disclosed (second prior art).

Further, in the piston structure described in Japanese Utility Model Publication No. 5-1709, a piston ring mounting groove is formed on the outer periphery of the piston, the ring-shaped piston ring is heated, and the piston ring is pressed against the outer periphery of the piston for mounting. (Third prior art).

[0006]

However, in the first prior art, a gap between both end faces of the piston ring is limited.
Since it is formed on the outer periphery of the piston so as to extend in the axial direction of the piston, the hydraulic oil leaks through the gap between the pressure chambers in the cylinder defined by the piston, and the damping force of the hydraulic shock absorber is impaired. It will be stable.

In the second prior art, since the piston ring has a ring shape, a gap is not formed in the piston ring as in the first prior art, but a holding member for holding the piston ring is attached to the piston. Therefore, the number of parts increases.

Further, in the third prior art, after forming the piston, a piston ring mounting groove for mounting the piston ring must be additionally formed on the outer periphery of the piston. Further, after heating the ring-shaped piston ring, the piston ring is mounted on the outer periphery of the piston, so that a taper jig or the like is required for mounting the piston ring, and mounting of the piston ring is complicated.

SUMMARY OF THE INVENTION The object of the present invention has been made in view of the above circumstances, and it is possible to eliminate the machining of the piston ring mounting groove on the piston and to facilitate the mounting of the piston ring on the piston. It is to provide a piston structure.

[0010]

According to a first aspect of the present invention, there is provided a hydraulic system in which a flow path is formed in the axial direction of a piston that slides in a cylinder, and a piston ring is mounted on an outer periphery of the piston. In the piston structure of the shock absorber, the piston is configured such that a first piston body and a second piston body are joined in the axial direction, and a recess is formed on an outer periphery facing a joining surface of the first and second piston bodies. A projection is formed on the inner periphery of the piston ring, and the projection is axially brought into contact with the projection of the piston ring and the recesses of the first and second piston bodies joined to each other. The piston ring is mounted on the outer periphery of the piston.

According to a second aspect of the present invention, in the first aspect of the present invention, the piston ring extends between joint surfaces of the first and second piston bodies and is held between these joint surfaces. The seat portion is integrally formed, and the seat portion is provided with an opening at a position corresponding to the flow path of the piston.

[0012] The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described in (1), a positioning projection is formed on one of the concave portion of the first and second piston bodies and a convex portion of the piston ring, and a positioning recess portion is formed on the other, which can be engaged with the positioning projection. Things.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the first piston body and the second piston body are formed in a symmetrical shape with respect to a joint surface. It is.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the joint surfaces of the first and second piston bodies include an axial force receiving portion that abuts each other,
A seat accommodating portion for accommodating the seat portion of the piston ring;
It is configured with.

The first aspect of the invention has the following operation. Since the piston ring is mounted on the piston by the concave portions of the first and second piston bodies sandwiching the convex portion of the piston ring in the axial direction, a piston ring mounting groove for mounting the piston ring is added to the outer periphery of the piston. The piston ring can be easily mounted on the piston without the need for modification.

Further, since the piston ring is mounted on the outer periphery facing the joint surface between the first and second piston bodies, even if the piston is formed by joining the first and second piston bodies, the piston ring is operated from these joint surfaces. Oil can be prevented from leaking, and a stable damping force can be generated.

Further, a round surface is formed on the end faces of the first and second piston bodies to contact the valve for generating the damping force and to affect the damping force. The first and second round surfaces have different shapes. If several types of two-piston bodies are prepared, the damping force generated by the hydraulic shock absorber can be easily changed by selecting the first and second piston bodies from these to form the pistons.

Further, since the piston is composed of the first and second piston bodies, even if one of the piston bodies is damaged, such as a scratch, it is sufficient to replace only one of the piston bodies. Can be reduced.

The second aspect of the invention has the following operation. A seat portion is integrally formed with the piston ring, and the seat portion is sandwiched between joint surfaces of the pistons in the first and first piston bodies.
Even if it is constituted by the second piston body, it is possible to prevent the hydraulic oil from leaking between the flow paths of the piston.

The third aspect of the invention has the following operation. Since the positioning projection is formed on one of the concave portions of the first and second piston bodies and the convex portion of the piston ring, and the positioning recess is formed on the other, the positioning projection and the positioning recess are engaged with each other. Thereby, the piston ring can be easily aligned with the predetermined positions of the first and second piston bodies, and assembly of the piston and the piston ring can be facilitated.

The invention described in claim 4 has the following operation. Since the first piston body and the second piston body are configured in a symmetrical shape with respect to the joint surface, the first and second piston bodies can be molded with the same mold (for example, a mold), and the cost can be reduced.

The fifth aspect of the invention has the following operation. An axial force receiving portion that abuts on each other is formed on the joint surface of the first and second piston bodies, so that the first and second piston bodies are abutted on the joint surface so as to be assembled and fixed. The applied axial force can be supported by the axial force receiving portions of both piston bodies. As a result, the first and second piston bodies can be properly held for a long time in a state where the axial force receiving portions are in contact with each other.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. (1) First Embodiment FIG. 1 shows a first embodiment of a piston structure of a hydraulic shock absorber according to the present invention.
FIG. 3 is a cross-sectional view showing a piston, a piston ring, and the like to which the embodiment is applied. FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 3 is a view taken in the direction of the arrow III in FIG. FIG.
FIG. 2 is a perspective view showing a state in which the piston ring of FIG. 1 is divided into two along the axis. FIG. 5 is a perspective view showing the piston of FIG.

As shown in FIG. 1, a piston 11 of a hydraulic shock absorber 10 is disposed in a cylinder 12, and a piston ring 13 is mounted on an outer peripheral surface thereof. Be composed. The inside of the cylinder 12 filled with the hydraulic oil by the piston 11 is liquid-tightly divided into two pressure chambers 14A and 14B by the piston 11 and the piston ring 13.
The piston ring 13 is mounted on the outer periphery of the piston 11 in order to improve the sealing performance, the sliding performance, and the wear resistance.

The piston 11 is constructed by joining a first piston body 15 and a second piston body 16 in the axial direction. Rod through holes 17 and 18 extending in the axial direction are formed coaxially at the center positions of the first piston body 15 and the second piston body 16, respectively. A piston rod 26 is inserted into these rod through holes 17 and 18.

Further, in the first piston body 15, a pressure side flow path 19 and a growth side flow path 20 are formed alternately in the axial direction around the rod through hole 17. Further, in the second piston body 16, a pressure-side flow path 21 and an extension-side flow path 22 are formed around the rod through-hole 18 alternately in the axial direction. The pressure side flow path 19 of the first piston body 15 and the pressure side flow path 21 of the second piston body 16 are provided coaxially, and the extension side flow path 20 of the first piston body 15 and the extension side of the second piston body 16 are extended. The side flow passages 22 are provided coaxially and constitute one through flow passage when the first piston body 15 and the second piston body 16 are joined.

A round surface 25 as shown in FIG. 3 is formed on the first piston body 15 and the second piston body 16 on the end surfaces facing the respective joint surfaces 23 and 24. Since the shape of the round surface 25 comes into contact with the compression side damping valve 27 and the expansion side attenuation valve 28 as described later, the shape of the round surface 25 affects the magnitude of the damping force generated by the compression side attenuation valve 27 and the expansion side attenuation valve 28. Exert.

Round surface 25 of first piston body 15
The pressure-side damping valve 27 shown in FIG. 1 is disposed in contact with the pressure-side damping valve 27, and the pressure-side damping valve 27 can close the unified pressure-side flow paths 19 and 21. These pressure side flow paths 19
The hydraulic oil flowing through the cylinder 21 causes the compression damping valve 27 to bend and deform, so that the piston rod 26 generates a damping force (compression side damping force) in the compression stroke of the hydraulic shock absorber 10 that enters the cylinder 12.

The round surface 25 of the second piston body 16
The expansion side damping valve 28 is disposed in contact with the expansion side damping valve 28, and the expansion side attenuation valve 28 is
Can be closed. The hydraulic oil flowing through these expansion-side flow paths 20 and 22 causes the expansion-side damping valve 28 to bend and deform.
During the extension stroke of the hydraulic shock absorber 10 in which the piston rod 26 withdraws from the cylinder 12, a damping force (extension damping force) is generated.

As shown in FIGS. 1 and 5, recesses 29 and 30 are formed on the outer periphery of the first piston body 15 and the second piston body 16 at positions facing the joint surfaces 23 and 24, respectively. These recesses 29 and 30 are formed over the entire circumference of the first piston body 15 and the second piston body 16 respectively, and positioning projections 31 are provided at predetermined locations in the circumferential direction.

Here, the first constructed as described above is used.
The piston body 15 and the second piston body 16 have symmetrical shapes with respect to the respective joint surfaces 23 and 24, and are formed by the same mold. 1st piston body 15, 2nd
One of the piston bodies 16 is inserted and arranged in the piston rod 26 with the other displaced by 180 °.

As shown in FIGS. 1, 2 and 4, the piston ring 13 has a convex portion 33 bulging over the entire inner periphery of a substantially cylindrical ring main body 32. And the sheet portion 34 is integrally formed to extend inward in the radial direction. This piston ring 13
For example, it is made of a synthetic resin. The projection 33 is formed by the recesses 29 and 30 of the first piston body 15 and the second piston body 16 in contact with each other.
The piston ring 13 is attached to the outer periphery of the piston 11 by being held in the axial direction of the piston 11.

The seat portion 34 of the piston ring 13
The compression-side flow path 19 and the extension-side flow path 20 of the first piston body 15 and the compression-side flow path 2 of the second piston body 16
An opening 35 is opened at a position corresponding to the first and extension side flow paths 22. First piston body 15 and second piston body 1
6, the seat portion 34 of the piston ring 13 is connected to the joint surface 23 of the first piston body 15 by the second
Since the first piston body 15 is sandwiched between the joint surfaces 24 of the piston bodies 16,
Pressure side flow path 19 and the pressure side flow path 2 of the second piston body 16
1, the hydraulic fluid is prevented from leaking, and the extension side flow path 20 of the first piston body 15 and the second piston body 16
Similarly, leakage of hydraulic oil is prevented between the flow path 22 and the extension side flow path 22.

Further, a positioning recess 36 is formed in the convex portion 33 of the piston ring 13 at a predetermined position in the circumferential direction of the piston ring 13. The positioning recessed portion 36 is provided so as to be engageable with the positioning protrusion 31 of the first piston body 15 and the second piston body 16, and in the engaged state, the piston ring 13 moves the first piston body 15 and the second piston body 16. , That is, the opening 35 of the piston ring 13 is
9 and the expansion side flow path 20 and the positions corresponding to the compression side flow path 21 and the expansion side flow path 22 of the second piston body 16.

The ring body 32 of the piston ring 13
Is configured to have an axial length that covers the entire outer peripheries of the joined first piston body 15 and second piston body 16, and includes a skirt portion 37. This piston ring 13
The skirt portion 37 contributes to further improving the sealing performance between the piston 11 and the cylinder 12.

In order to assemble the cylinder 12 and the piston ring 13 and the like to the piston rod 26, first, the valve stopper 38, the compression-side damping valve 27, and the first piston body 15 are sequentially inserted into the piston rod 26, and then, After inserting the piston ring 13 and then sequentially inserting the second piston body 16, the extension side damping valve 28 and the valve stopper 39, the nut 4 is attached to the tip of the piston rod 26.
0 is screwed and fixed. At this time, the first piston body 15 and the second piston body 16
An axial force for maintaining the joined state of the piston body 15 and the second piston body 16 is applied.

According to the above embodiment, the following effects are obtained. The concave portion 29 of the first piston body 15 and the concave portion 30 of the second piston body 16
Since the piston ring 13 is mounted on the piston 11 by sandwiching the piston ring 13 in the axial direction, there is no need to additionally perform a piston ring mounting groove for mounting the piston ring 13 on the outer periphery of the piston 11, and the piston ring 13 can be eliminated. The piston ring 13 can be easily mounted on the piston 11.

Further, since the piston ring 13 is mounted on the outer periphery facing the joint surface 22 of the first piston body 15 and the joint surface 24 of the second piston body 16, the piston 1
1 is a first piston body 15 and a second piston body 1
6 are joined together, these joining surfaces 2
The hydraulic oil can be prevented from leaking from 3, 24, and a stable damping force can be generated in the hydraulic shock absorber 10.

Further, the first piston body 15 and the second
On the end face of the piston body 16, there is formed a round surface 25 which abuts on the compression side damping valve 27 and the extension side damping valve 28 which generate a damping force and affects the damping force. If several types of the piston body 15 and the second piston body 16 are prepared, by selecting the first piston body 15 and the second piston body 16 from these to configure the piston 11,
The damping force generated by the hydraulic shock absorber 10 can be easily changed.

The piston is the first piston body 1
5 and the second piston body 16, even if one of the first piston body 15 and the second piston body 16 is damaged, such as a scratch, if only one of the piston bodies 15 or 16 is replaced, Since it is sufficient, the cost can be reduced.

The seat portion 34 is formed integrally with the piston ring 13, and the joint surface 23 of the first piston body 15 is formed.
Also, since the seat portion 34 is sandwiched between the joint surfaces 24 of the second piston body 16, even when the piston 11 is constituted by the first piston body 15 and the second piston body 16, Between the flow paths (the pressure side flow path 19 of the first piston body 15 and the second piston body 16
Between the pressure side flow path 21 and the expansion side flow path 20 of the first piston body 15 and the expansion side flow path 22 of the second piston body 16).
Leakage of hydraulic oil can be prevented.

The positioning projections 31 are formed in the concave portions 29 of the first piston body 15 and the concave portions 30 of the second piston body 16.
Are formed, and positioning recesses 36 are formed in the projections 33 of the piston ring 13.
1 is engaged with the positioning recess 36 to open the opening 35 of the piston ring 13 into the first piston body 15.
Pressure side flow path 19 and the pressure side flow path 2 of the second piston body 16
1. The extension side flow path 20 of the first piston body 15 and the extension side flow path 22 of the second piston body 16 can be made to correspond. For this reason, the piston ring 13 can be easily aligned with the predetermined positions of the first piston body 15 and the second piston body 16, and the assembly of the piston 11 and the piston ring 13 can be facilitated.

Since the first piston body 15 and the second piston body 16 are formed in symmetrical shapes with respect to the respective joint surfaces 23 and 24, the first piston body 15 and the second piston body 16 are formed by the same mold. It can be molded and cost can be reduced.

(2) Second Embodiment FIG. 6 shows a second embodiment of the piston structure of the hydraulic shock absorber according to the present invention.
It is sectional drawing which shows the piston and piston ring to which Embodiment of this invention was applied. FIG. 7 is a sectional view taken along the line VII-VII in FIG. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The piston 41 of this embodiment is configured by joining a first piston body 42 and a second piston body 43. On the joint surface of the first piston body 42,
An axial force receiving portion 44 is continuously formed on the rod through hole 17 side, and a sheet portion 46 is continuously formed on the compression side flow channel 19 and the extension side flow channel 20 side. Similarly, on the joint surface of the second piston body 43, an axial force receiving portion 45 is continuously formed on the rod insertion hole 18 side, and a sheet housing portion 47 is continuously formed on the compression side flow passage 21 and the expansion side flow passage 22 side. .

The axial force receiving portions 44 and 45 are formed on flat surfaces orthogonal to the axial direction of the first piston body 42 and the second piston body 43, respectively, and join the first piston body 42 and the second piston body 43. In this state, the first piston body 42 and the second piston body 43 are in contact with each other to support the axial force for maintaining the joined state between the first piston body 42 and the second piston body 43. Further, the sheet accommodating portions 46 and 47 are provided between the first piston body 42 and the second piston body 42.
There is a gap in the joint state with the piston body 43, and the first
Hydraulic oil flows between the compression side flow path 19 of the piston body 42 and the compression side flow path 21 of the second piston body 43 and between the expansion side flow path 20 of the first piston body 42 and the expansion side flow path 22 of the second piston body 43, respectively. The seat portion 34 of the piston ring 13 is accommodated so as to sandwich the seat portion 34 with an appropriate force capable of preventing leakage.

The axial force receiving portion 4 of the first piston body 42
The seat 4, the seat housing 46, and the axial force receiving portion 45 of the second piston body 43 and the seat housing 47 are formed at different positions along the axial direction of the piston 41 with steps. Further, the first piston body 42 having the axial force receiving portion 44 and the sheet accommodating portion 46 and the second piston body 43 having the axial force receiving portion 45 and the sheet accommodating portion 47 have symmetrical shapes with respect to their joint surfaces. It is formed and molded in the same mold.

The recess 29 of the first piston body 42 and the recess 30 of the second piston body 43 as described above
The projection 4 of the piston ring 13 is sandwiched and the piston 4
The present embodiment in which the piston ring 13 is mounted on the outer periphery of the first embodiment also has the effects (1) to (3) of the above embodiment.
Further, the present embodiment has the following effects.

As in the above embodiment, the first piston body 15 and the second piston body 16 are connected to the seat portion 34 of the piston ring 13 from the joint surface 23 of the first piston body 15 and the joint surface 24 of the second piston body 16. When all the axial force for assembling and fixing acts, if the piston ring 13 is made of resin, the seat portion 34 of the piston ring 13 is plastically deformed and thinned by the action of the long-term axial force, The first piston body 15 and the second
In some cases, it may not be possible to secure an appropriate axial force on the piston body 16.

On the other hand, in the present embodiment, the joint surface between the first piston body 42 and the second piston body 43
Since the axial force receiving portions 44 and 45 that are in contact with each other are formed,
The axial force applied to hold and fix the first piston body 42 and the second piston body 43 in contact with each other at the joint surface is applied to the axial force receiving portion 44 of the first piston body 42 and the second piston. It can be supported by the axial force receiving portion 45 of the body 43. As a result, the first piston body 42 and the second piston body 43 can be properly held for a long time in a state where the axial force receiving portions 44 and 45 are in contact with each other.

In the second embodiment, the axial force receiving portion 44 of the first piston body 42 and the seat accommodating portion 46 are not formed with a step, and the axial force receiving portion 45 of the second piston body 43 and the seat The housing portion 47 and the housing portion 47 may not be formed with a step, but may be formed at the same level in the axial direction of the piston 41. Also, the first piston body 15,
42 and recesses 30 of the second piston bodies 16 and 43 are formed with positioning recesses 36, so that the piston ring 1
The positioning protrusion 31 may be formed on the third protrusion 33.

[0052]

As described above, according to the piston structure of the hydraulic shock absorber according to the present invention, the machining of the piston ring mounting groove on the piston can be eliminated, and the attachment of the piston ring to the piston can be facilitated.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a piston, a piston ring, and the like to which a first embodiment of a piston structure of a hydraulic shock absorber according to the present invention is applied.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a view taken in the direction of arrow III in FIG. 1;

FIG. 4 is a perspective view showing the piston ring of FIG. 1 divided into two along the axis.

FIG. 5 is a perspective view showing the piston of FIG. 1;

FIG. 6 is a sectional view showing a piston and a piston ring to which a second embodiment of the piston structure of the hydraulic shock absorber according to the present invention is applied.

FIG. 7 is a sectional view taken along line VII-VII in FIG. 6;

[Explanation of symbols]

 Reference Signs List 10 hydraulic shock absorber 11 piston 12 cylinder 13 piston ring 15 first piston body 16 second piston body 23 joint surface of first piston body 24 joint surface of second piston body 25 round surface 29 concave portion of first piston body 30 second Recessed part of piston body 31 Positioning protrusion 33 Convex part of piston ring 34 Seat part of piston ring 35 Opening of seat part 36 Positioning depression part 41 Piston 42 First piston body 43 Second piston body 44 Axial force receiving part of first piston body 45 Axial force receiving portion of second piston body 46 Seat receiving portion of first piston body 47 Seat receiving portion of second piston body

Claims (5)

[Claims] 1. A piston structure of a hydraulic shock absorber in which a flow passage is formed in the axial direction of a piston that slides in a cylinder, and a piston ring is mounted on an outer periphery of the piston. The piston body and the second piston body are joined in the axial direction, and a concave portion is formed on the outer periphery facing the joint surface of the first and second piston bodies, and a convex portion is formed on the inner periphery of the piston ring. A portion is formed, and the piston ring is mounted on the outer periphery of the piston by axially contacting the convex portion of the piston ring and the concave portions of the first and second piston bodies joined to each other. A piston structure of a hydraulic shock absorber, characterized in that: 2. The first and second piston rings are provided on the piston ring.
2. A seat portion extending between joint surfaces of the piston body and sandwiched between the joint surfaces is integrally formed, and an opening is provided in the seat portion at a position corresponding to the flow path of the piston. The piston structure of the hydraulic shock absorber according to the above. 3. A positioning projection is formed on one of the recessed portions of the first and second piston bodies and a projection of the piston ring, and a positioning recessed portion is formed on the other, which is engageable with the positioning projection. Item 3. A piston structure of the hydraulic shock absorber according to item 1 or 2. 4. The piston structure of a hydraulic shock absorber according to claim 1, wherein said first piston body and said second piston body are formed in a symmetrical shape with respect to a joint surface. 5. The joint surface of the first and second piston bodies includes an axial force receiving portion abutting on each other, and a seat accommodating portion accommodating a seat portion of the piston ring. 3. The piston structure of the hydraulic shock absorber according to any one of 3.