JP2008138696A - Divided piston structure for hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply secure sealing performance of butting surfaces of a piston and a separator in a divided piston structure for a hydraulic shock absorber. <P>SOLUTION: In the divided piston structure for the hydraulic shock absorber 10, an endless circumferential projection 34 surrounding oil passages 22, 31 provided on the piston 20 and the separator 30 is provided for one of the butting surfaces of the piston 20 and the separator 30. The projection 34 is crushed by fastening force of a nut 45 fastening the piston and the separator 30 on a piston rod 12, and is butted on another of the butting surfaces of the piston 20 and the separator 30 without a gap. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a split piston structure of a hydraulic shock absorber.

  In general, in a vehicle, in order to buffer vibrations and shocks received by the vehicle body due to road surface unevenness, a piston is slid in an expansion side and a compression side in a cylinder filled with hydraulic oil, and an oil passage on the extension side or pressure side of the piston is provided. A hydraulic shock absorber is provided that controls the flow of hydraulic oil passing therethrough by opening and closing disk valves provided in the oil passages, and generates a damping force.

Some conventional hydraulic shock absorbers employ a split piston structure having a piston and a separator provided in accordance with the end face of the piston, as described in Patent Document 1, and communicate with the piston and the separator. And a disk valve that opens and closes the oil passage is seated on the valve seat of the separator. The separator valve seat can be expanded so that the outer diameter of the disc valve can be set as large as possible, the disc valve can be easily elastically deformed, and the damping force can be changed sharply in response to changes in the piston speed. It is something that can be done.
JP-A-8-261268

  In the prior art, the piston and the separator are formed of a sintered material, and the flatness of their mating surfaces is accompanied by variations in manufacturing accuracy. When a gap is generated between the mating surfaces of the piston and the separator due to variations in their flatness, the two oil chambers partitioned by the piston in the cylinder communicate directly with, for example, one oil chamber. The oil passage of the piston is directly connected to the other oil chamber through the gap without passing through the oil passage of the separator and the disk valve. When hydraulic oil leaks between the two oil chambers through the gap, the damping force due to the elastic deformation of the disk valve is reduced, and the damping force characteristic varies between each hydraulic shock absorber as a product. Will occur.

  Therefore, in Patent Document 1, in order to eliminate the gap between the mating surfaces of the piston and the separator, each of the mating surfaces is provided with an endless circular projection and a groove surrounding the oil passage provided in the piston and the separator. The protrusion and the groove are fitted with a sealant interposed between the protrusion and the groove.

  However, according to Patent Document 1, it is necessary to provide a sealing material as a separate member on the mating surface of the piston and the separator, and the shape of the mating surface becomes complicated because the sealing material is provided.

  An object of the present invention is to easily ensure the sealing performance of the mating surfaces of a piston and a separator in a divided piston structure of a hydraulic shock absorber.

  The invention according to claim 1 includes a piston and a separator provided in accordance with the end face of the piston, and includes an oil passage provided in communication with the piston and the separator, and a disc valve for opening and closing the oil passage is provided as a valve seat of the separator. In a split piston structure of a hydraulic shock absorber that is separated from and seated on one side, an endless circular protrusion surrounding an oil passage provided in the piston and separator is provided on one of the mating surfaces of the piston and separator, and the piston and separator are fastened to the piston rod. The protrusion is crushed by the tightening force of the nut and is brought into contact with the other of the mating surfaces of the piston and the separator without any gap.

  According to a second aspect of the present invention, in the first aspect of the present invention, the projection is an annular shape centering on a central axis of the piston and the separator.

(Claim 1)
(a) In a split piston structure of a hydraulic shock absorber, an endless circumferential projection surrounding an oil passage provided in the piston and separator is provided on one of the mating surfaces of the piston and separator, and the nut that fastens the piston and separator to the piston rod The above-mentioned protrusion was crushed by the tightening force, and was brought into contact with the other of the mating surfaces of the piston and the separator without any gap. That is, the piston and the separator are fastened to the piston rod, and at the same time, the protrusion is brought into contact with the mating surface and crushed, so that the sealing performance of the mating surface of the piston and the separator can be ensured. It is not necessary to provide a sealing material as a separate member, and the shape of the piston is simple and sufficient.

  Therefore, the two oil chambers partitioned by the piston in the cylinder are connected, for example, from the oil passage of the piston directly communicating with one of the oil chambers without passing through the oil passage and the disk valve of the separator. There is no possibility of communicating directly with the other oil chamber through the gap between the mating surfaces. As a result, the hydraulic oil does not leak between the two oil chambers through the gap, so that the damping force due to the elastic deformation of the disk valve does not decrease, and each hydraulic shock absorber as a product There is no variation in damping force characteristics between the two.

(Claim 2)
(b) Since the projection in (a) is an annular shape centering on the central axis of the piston and separator and surrounding the oil passage provided in the piston and separator, the mounting angle position of the piston and separator around their central axes Can be combined simply by superimposing without positioning each other.

  1 is a sectional view showing a divided piston structure of a hydraulic shock absorber, FIG. 2 is a sectional view showing a piston, FIG. 3 is an end view showing a pressure side disk valve seating surface of FIG. 2, and FIG. 4 is a separator mating surface of FIG. FIG. 5 shows a separator, FIG. 5A is a cross-sectional view, FIG. 5B is an enlarged view of a main part, FIG. 6 is a cross-sectional view showing an extension side disk valve seating surface of FIG. FIG. 8 is an enlarged cross-sectional view of the main part of FIG.

  A hydraulic shock absorber 10 shown in FIG. 1 constitutes a split piston structure by fixing a piston 20 and a separator 30 to a piston rod 12 inserted into a cylinder 11.

  As shown in FIGS. 2 to 4, the piston 20 is formed of a sintered material and includes a piston ring 20 </ b> A made of a resin material fitted on the outer periphery. The piston 20 is in sliding contact with the cylinder 11 via a piston ring 20A, and the cylinder 11 partitions a rod side oil chamber 11A and a piston side oil chamber 11B.

  The piston 20 is provided with a plurality of pressure side oil passages 21 and a plurality of extension side oil passages 22 communicating with both the oil chambers 11A and 11B from one end surface to the other end surface. In the present embodiment, the pressure side oil passage 21 is arranged on the large diameter side from the central axis of the piston 20 (the central axis of the piston rod 12), and the expansion side oil passage 22 is arranged on the small diameter side from the central axis of the piston 20.

  As shown in FIGS. 2 and 3, the piston 20 is provided with a pressure side valve seat 23 as a non-circular pressure side round surface on which the pressure side disk valve 41 is detachably seated on an end face facing the rod side oil chamber 11A. A pressure side oil passage 21 is opened inside the valve seat 23 (on the piston rod 12 side), and an extension side oil passage 22 is opened outside the pressure side valve seat 23. The pressure side disc valve 41 opens and closes the pressure side oil passage 21. A valve support 23 </ b> A that supports the pressure-side disc valve 41 is provided in a portion sandwiched between the openings of the two pressure-side oil passages 21 adjacent to each other inside the pressure-side valve seat 23. The compression side disk valve 41 is formed by laminating a large number of thin metal plates having spring properties.

  As shown in FIGS. 2 and 4, the piston 20 is provided with a planar mating surface 24 on which the separator 30 is placed on the end surface facing the piston-side oil chamber 11B, and the radial direction of the mating surface 24 is directed outwardly with the pressure side oil. The extension side oil passage 22 is opened through the passage 21 radially inward. The piston 20 includes an annular recess 24 </ b> A that is continuous in the circumferential direction including the opening of the extension side oil passage 22 on the mating surface 24.

  As shown in FIGS. 5 to 7, the separator 30 is formed of a sintered material and has an annular gap between the separator 30 and the cylinder 11. The separator 30 includes a plurality of extended-side oil passages 31 formed from one end surface to the other end surface. The radial distance that the expansion side oil passage 31 forms with respect to the central axis of the separator 30 (the central axis of the piston rod 12) is made by the expansion side oil passage 22 with respect to the central axis of the piston 20 (the central axis of the piston rod 12). It is almost the same as the radial distance.

  As shown in FIGS. 5 and 6, the separator 30 is provided with a planar mating surface 32 on which the mating surface 24 of the piston 20 is superimposed and abutted on the end surface located on the piston 20 side. The oil passage 31 is opened. The separator 30 includes an annular recess 32 </ b> A that is continuous in the circumferential direction including the opening of the extended oil passage 31 on the mating surface 32. When the mating surface 32 of the separator 30 is superimposed on the mating surface 24 of the piston 20, the annular recess 24A of the piston 20 and the annular recess 32A of the separator 30 are aligned with each other.

  As shown in FIGS. 5 and 7, the separator 30 is provided with an expansion side valve seat 33 as an annular expansion side round surface on which an expansion side disk valve 42 is detachably seated on an end surface facing the piston side oil chamber 11B. The extension side oil passage 31 is opened inside the extension side valve seat 33 (on the piston rod 12 side). The extension side disk valve 42 opens and closes the extension side oil passages 22 and 31. The extension side disk valve 42 is formed by laminating a large number of thin metal plates having spring properties.

  In the hydraulic shock absorber 10, the pressure side oil passage 21 is disposed on the large diameter side from the central axis of the piston 20, the expansion side oil passage 22 is disposed on the small diameter side, and the rod side oil chamber 11 </ b> A side of the piston 20 is disposed. A pressure side valve seat 23 as a non-annular pressure side round surface on which the pressure side disk valve 41 is placed was formed on the facing end surface. In the hydraulic shock absorber 10 without the separator 30, when the expansion side valve seat 33, which is an annular expansion side round surface on which the expansion side disk valve 42 is mounted, is formed on the end surface of the piston 20 facing the piston side oil chamber 11B, the compression side Due to the arrangement of the oil passage 21 and the extension side oil passage 22, only the extension side valve seat 33 having a small diameter can be formed, and the outer diameter of the extension side disk valve 42 cannot be set as large as possible. Therefore, in this embodiment, the mating surface 32 of the separator 30 is superimposed on the mating surface 24 of the end surface facing the piston-side oil chamber 11B side of the piston 20, and the extension side of the separator 30 is placed in the extension-side oil passage 22 of the piston 20. An expansion side valve seat 33, which is a large-diameter annular expansion side round surface, is formed on the end surface facing the piston side oil chamber 11B of the separator 30 through the oil passage 31, and as a result, the expansion side valve seat 33 is expanded. The outer diameter of the extension side disk valve 42 can be set as large as possible.

  Therefore, as shown in FIG. 1, the hydraulic shock absorber 10 has a valve presser 43, a pressure side disc valve 41, a piston 20, a separator 30, an extension side disc valve 42, and a valve presser 44 on the small diameter portion on the tip end side of the piston rod 12. These are inserted in order, and these are fastened and fixed by a nut 45 screwed to the tip of the piston rod 12. The mating surface 32 of the separator 30 abuts on the mating surface 24 of the piston 20, and the annular recess 24 </ b> A of the piston 20 and the annular recess 32 </ b> A of the separator 30 are independent of each other regardless of the mounting angle position around the central axis of the piston 20 and separator 30. Match.

  When the hydraulic shock absorber 10 is used, when the piston rod 12 is displaced to the extension side, the high pressure hydraulic oil in the rod side oil chamber 11A is aligned with the extension side oil passage 22 of the piston 20, the annular recess 24A of the mating surface 24, and the separator 30. It acts on the extension-side disc valve 42 via the annular recess 32 </ b> A of the surface 32 and the extension-side oil passage 31. When the extension side disk valve 42 is separated from the extension side valve seat 33 of the separator 30, the hydraulic oil in the rod side oil chamber 11A flows into the piston side oil chamber 11B, and a damping force is generated by the flow of the hydraulic oil.

  On the other hand, when the piston rod 12 is displaced to the compression side, the high pressure hydraulic oil in the piston side oil chamber 11 </ b> B acts on the pressure side valve 41 via the pressure side oil passage 21 of the piston 20. When the pressure side valve 41 is separated from the pressure side valve seat 23 of the piston 20, the hydraulic oil in the piston side oil chamber 11B flows into the rod side oil chamber 11A, and a damping force is generated by the flow of the hydraulic oil.

  However, the hydraulic shock absorber 10 has the following configuration in order to ensure the sealing performance of the mating surfaces 24 and 32 of the piston 20 and the separator 30.

  One of the mating surface 24 of the piston 20 and the mating surface 32 of the separator 30, in this embodiment, on the mating surface 32 of the separator 30, the extension side oil passage 22 provided in the piston 20 and the separator 30 (annular recess 24 </ b> A of the mating surface 24). Further, an endless circular projection (projection) 34 surrounding the extension-side oil passage 31 (annular recess of the mating surface 32) is provided. The fine protrusions 34 are simultaneously formed by the mold when the separator 30 is sintered. Then, the fine protrusion 34 is crushed by the tightening force of the nut 45 that fastens the piston 20 and the separator 30 to the piston rod 12, and is brought into contact with the mating surface 24 of the piston 20 without any gap. The fine protrusions 34 of the present embodiment form an annular shape centering on the central axis of the piston 20 and the separator 30 (the central axis of the piston rod 12). In this embodiment, the fine protrusion 34 has an arcuate (triangular or trapezoidal) cross section as shown in FIG. 5B, and the arc radius r = 0.1 mm to 0.3 mm, preferably 0.2 mm. The height h of the arc is 0.03 mm to 0.10 mm, preferably 0.05 mm.

According to the present embodiment, the following operational effects can be obtained.
(a) In the divided piston structure of the hydraulic shock absorber 10, an endless circumferential fine protrusion 34 surrounding one of the mating surfaces 24, 32 of the piston 20 and the separator 30 and surrounding the oil passages 22, 31 provided in the piston 20 and the separator 30. The fine protrusions 34 are crushed by the tightening force of the nut 45 that fastens the piston 20 and the separator 30 to the piston rod 12 so as to contact the other of the mating surfaces 24 and 32 of the piston 20 and the separator 30 without any gap. . That is, the sealing performance of the mating surfaces 24 and 32 of the piston 20 and the separator 30 can be ensured by fastening the piston 20 and the separator 30 to the piston rod 12 and simultaneously crushing the fine protrusions 34 against the mating surface 24. It is not necessary to provide a sealing material as a separate member, and the shape of the piston 20 is simple and sufficient.

  Accordingly, the two oil chambers 11A and 11B defined by the piston 20 in the cylinder 11 are connected to the oil passage 31 of the separator 30 and the disc from the oil passage 22 of the piston 20 directly communicating with one of the oil chambers 11A, for example. There is no possibility of communicating directly with the other oil chamber 11 </ b> B through the gap between the mating surfaces 24 and 32 of the piston 20 and the separator 30 without using the valve 42. As a result, the hydraulic oil does not leak through the gap between the two oil chambers 11A and 11B, so that the damping force due to the elastic deformation of the disc valve 42 does not decrease, and each product as a product. There is no variation in damping force characteristics between the hydraulic shock absorbers 10.

  (b) Since the fine protrusion 34 of (a) has an annular shape around the central axis of the piston 20 and the separator 30 and surrounding the oil passages 22 and 31 provided in the piston 20 and the separator 30, the piston 20 and the separator 30. Can be combined by simply superimposing them without positioning their mounting angle positions around their central axes.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, the projection 34 provided on the mating surface 24 of the piston 20 or the mating surface 32 of the separator 30 is not an annular shape centered on the central axis thereof, but has a different shape, or surrounds one opening of each oil passage 22, 31. A protrusion may be used (the four oil passages 22 and 31 are protrusions surrounding each one of them). At this time, the piston 20 and the separator 30 are positioned relative to each other by their positioning projections, notches, and the like at their mounting angle positions around their central axes.

  Moreover, the damping force characteristics of the hydraulic shock absorber 10 can be variously changed by replacing the separators 30 with various sizes and shapes on the piston 20.

FIG. 1 is a sectional view showing a divided piston structure of a hydraulic shock absorber. FIG. 2 is a sectional view showing the piston. FIG. 3 is an end view showing the pressure side disk valve seating surface of FIG. FIG. 4 is an end view showing the separator mating surface of FIG. 5A and 5B show a separator, in which FIG. 5A is a cross-sectional view and FIG. FIG. 6 is a cross-sectional view showing the extending side disk valve seating surface of FIG. FIG. 7 is an end view showing the piston mating surface of FIG. FIG. 8 is an enlarged cross-sectional view of the main part of FIG.

Explanation of symbols

10 Hydraulic shock absorber 20 Piston 22 Oil passage 24 Matching surface 30 Separator 31 Oil passage 32 Matching surface 33 Valve seat 34 Projection 42 Disc valve 45 Nut

Claims (2)

Having a piston and a separator provided in accordance with the end face of the piston;
In a divided piston structure of a hydraulic shock absorber provided with an oil passage provided in communication with a piston and a separator, and a disk valve that opens and closes the oil passage is seated on and away from a valve seat of the separator.
On one of the mating surfaces of the piston and the separator, an endless circular projection surrounding the oil passage provided in the piston and the separator is provided. A split piston structure for a hydraulic shock absorber, which is in contact with the other of the mating surfaces without any gap.   2. The split piston structure for a hydraulic shock absorber according to claim 1, wherein the protrusion has an annular shape centering on a central axis of the piston and the separator.

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