JP3383865B2 - Hydraulic shock absorber - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile. 2. Description of the Related Art A hydraulic shock absorber generally mounted on a vehicle suspension will be described with reference to FIGS. 11 and 12. FIG. As shown in FIGS. 11 and 12, a hydraulic shock absorber 1 has a piston 3 slidably fitted in a cylinder 2 in which an oil solution is sealed. Are defined in two chambers, an upper cylinder chamber 2a and a lower cylinder chamber 2b. One end of a piston rod 4 is connected to the piston 3 by a nut 5. The other end of the piston rod 4 is connected to a rod guide (not shown) provided at the end of the cylinder 2 and an oil seal (not shown). ) And extended to the outside. The cylinder 2 is connected to a reservoir (not shown) for compensating for a change in volume caused by expansion and contraction of the piston rod 4 by compressing and expanding the gas. [0004] The piston 3 is provided with a plurality of extension communication passages 6 and a contraction communication passage 7 for communicating the cylinder upper chamber 2a and the cylinder lower chamber 2b (four in the drawing). Has been established. The extension-side communication passage 6 has an opening on the outer peripheral portion of the end face of the piston 3 on the cylinder upper chamber 2a side, and has an opening on the inner peripheral portion on the end face of the piston 3 on the cylinder lower chamber 2b side. The contraction side communication passage 7 has an opening on the inner peripheral portion of the end face of the piston 3 on the cylinder upper chamber 2a side and an opening on the outer peripheral portion of the end face of the piston 3 on the cylinder lower chamber 3b side. An annular valve seat 8 protrudes from the end face of the piston 3 on the side of the cylinder lower chamber 2b on the inner and outer circumferences of the opening of the extension side communication passage 6. The disk valve 9 faces the valve seat 8 in opposition to the valve seat 8.
Is provided. On the end surface of the piston 3 on the side of the cylinder upper chamber 2a, an annular valve seat is provided on the inner and outer circumferences of the opening of the contraction side communication passage 7.
A disk valve 11 is provided so as to face the valve seat 10. The operation of the hydraulic shock absorber 1 configured as described above will be described below. During the extension stroke of the piston rod 4, the contraction side communication passage 7 is closed by the disc valve 11, and the oil liquid in the cylinder upper chamber 2a passes through the extension side communication passage 6 to open the disc valve 9 to open the cylinder lower chamber 2b. Side, and a damping force is generated according to the opening of the disc valve 9. Further, during the contraction stroke, the extension side communication passage 6 is closed by the disk valve 9, and the oil liquid in the cylinder lower chamber 2 b side opens the disk valve 11 through the contraction side communication path 7, flows to the cylinder upper chamber 2 a side, and A damping force is generated according to the opening of the valve 11. At this time, when the disc valves 9 and 11 are opened at the opening corresponding to the pressure of the oil liquid, damping force having valve characteristics in which the damping force linearly increases in proportion to the increase in the piston speed is generated. . The damping force characteristics on the extension side and the contraction side are respectively determined by the passage area of the extension side communication path 6 and the spring characteristic of the disc valve 9, and the passage area of the contraction side communication path 7 and the spring characteristic of the disc valve 11. Can be set. [0009] However, the conventional hydraulic shock absorber shown in FIGS. 11 and 12 has the following problems. That is, the expansion-side communication passage 6 and the contraction-side communication passage 7 are opened at the inner peripheral portion and the outer peripheral portion of the end face of the piston 3, and are opposed to the inner peripheral opening portion.
Are provided, the outer diameters of the disc valves 9 and 11 are limited by the openings on the outer peripheral sides of the extension side communication path 6 and the contraction side communication path 7, and the outer diameters of the disc valves 9 and 11 cannot be increased. . For this reason, the pressure receiving areas of the disk valves 9 and 11 cannot be made sufficiently large, so that it is difficult to set the inclination of the valve characteristics to be small, and there is a problem that the degree of freedom in setting the damping force characteristics is reduced. In general, the piston 3 is molded by sintering. However, since the extension side communication passage 6 and the contraction side communication passage 7 are provided to be inclined with respect to the axial direction of the piston 3, the piston 3 After molding, it is necessary to form a hole in the extension-side communication passage 6 and the contraction-side communication passage 7, and there is a problem that the processing is troublesome. In particular, when a low damping force is set, it is necessary to provide a large number of extension-side communication passages 6 and contraction-side communication passages 7 in order to increase the passage area. In Japanese Utility Model Laid-Open No. 59-142538, a first piston having an extension side communication path and a contraction side communication path is slidably fitted in a cylinder, and one end of the first piston is provided. A second piston having a large-diameter disc valve opposed to the compression-side passage, and an oil-liquid passage having a slightly smaller diameter than the first piston and communicating with the extension-side communication passage at the other end. And a large-diameter disk valve is provided at the end of the second piston so as to face the oil-liquid passage, so that the expansion-side and contraction-side disk valves have a large diameter. . However, even in the hydraulic shock absorber described in the above publication, there is a problem similar to that shown in FIGS. 11 and 12, since it is necessary to form a hole in the extension side passage and the contraction side passage. The present invention has been made in view of the above point, and has a hydraulic shock absorber in which the diameter of a disc valve is increased and the passage area of an extension side and a contraction side communication passage can be sufficiently increased. The purpose is to provide. [0014] In order to solve the above-mentioned problems, a hydraulic shock absorber according to the present invention is provided with a cylinder filled with an oil solution, and a slidably fitted inside of the cylinder. A cylindrical piston that defines the interior of the cylinder as two chambers, a piston rod one end of which is fixedly penetrated through the piston, and the other end of which extends to the outside of the cylinder; A pair of extension-side communication passages drilled along the axial direction at opposing positions, and a pair of extension-side communication passages drilled along the axial direction at positions opposing the piston rod between the pair of extension-side communication passages of the piston. And a pair of compression-side communication passages provided, and one end of the cylindrical portion of the piston surrounding the piston rod and the pair of extension-side communication passages and not surrounding the pair of compression-side communication passages. Abut against the end face An extension-side valve seat member having the other end of the cylindrical portion serving as a valve seat; an extension-side disc valve provided on the other end side of the extension-side valve seat member so as to close the cylindrical portion; One end of the cylindrical portion surrounds the piston rod and the pair of contraction side communication passages and abuts against the other end surface of the piston so as not to surround the pair of extension side communication passages, and the other end of the cylinder portion has a valve seat. And a disc valve provided on the other end of the contraction-side valve seat member so as to close the cylindrical portion. According to the above configuration, according to the hydraulic shock absorber of the present invention, during the extension stroke of the piston rod, the oil in the cylinder flows through the extension side communication passage due to the sliding of the piston. A damping force is generated by the expansion-side disk valve, and during the contraction stroke, the oil in the cylinder flows through the compression-side communication passage due to sliding of the piston, and a damping force is generated by the compression-side disk valve. At this time, since the extension side and the contraction side valve seat members are provided, the diameters of the extension side and the contraction side disc valves can be increased, and the extension side and the contraction side communication passage, and the extension side and the contraction side valve are provided. Since the two chambers in the cylinder communicate with each other through the cylindrical portion of the seat member, it is possible to increase the passage area of the oil liquid in the extending stroke and the contracting stroke. Further, since the extension-side communication passage and the compression-side communication passage of the piston are provided along the axial direction, molding can be easily performed. Embodiments of the present invention will be described below in detail with reference to the drawings. A first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2,
The hydraulic shock absorber 12 has a double-cylinder structure in which an outer cylinder 14 is provided outside the cylinder 13, and a piston 15 is slidably fitted in the cylinder 13. It is defined as two chambers, a chamber 13a and a cylinder lower chamber 13b. One end of a piston rod 16 is connected to the piston 15 by a nut 17, and the other end of the piston rod 16 is inserted into a rod guide 18 and an oil seal 19 mounted on upper ends of a cylinder 13 and an outer cylinder 14. Extending to the outside of the cylinder 13. A reservoir 20 is formed between the cylinder 13 and the outer cylinder 14, and the reservoir 20 and the cylinder lower chamber 13
b are communicated by the base valve 21 with an appropriate flow resistance. The cylinder 13 is filled with an oil liquid, and the reservoir 20 is filled with an oil liquid and a gas.The change in the volume of the cylinder 13 caused by the expansion and contraction of the piston rod 16 causes the compression of the gas in the reservoir 20. , Expansion to compensate. As shown in FIG. 3, the piston 15 is provided with a pair of extension-side communication passages 22 and contraction-side communication passages 23 with the central axis interposed therebetween. The extension-side communication passage 22 and the contraction-side communication passage 23 are long holes that penetrate along the axial direction of the piston 15 and are open along the circumferential direction, and are arranged annularly along the circumferential direction. The extension-side communication passage 22 and the contraction-side communication passage 23 are arranged at positions different from each other by 90 °. Piston 15 has a mounting hole for inserting a piston rod in the center
24, and a seal ring 25 is mounted on the outer peripheral portion. 1 and 2 are longitudinal sectional views taken along lines (orthogonal lines) passing through the extension-side communication passage 22 and the contraction-side communication passage 23. At both ends of the piston 15, a substantially cylindrical bottom-side extending valve seat member 26 and a contracting-side valve seat member 27 are provided. The extension-side valve seat member 26 and the contraction-side valve seat member 27 have an opening abutting on both ends of the piston 15, and one end of the piston rod 16 is fitted into mounting holes 28, 29 provided at the center of the bottom. The nut 15 is screwed into the distal end of the piston, and is connected to the piston rod 16 integrally with the piston 15. The extension side chamber is provided inside the extension side valve seat member 26.
26a are formed, and the contraction side chamber 27 is provided inside the contraction side valve seat member 27.
a is formed. Here, as shown in FIGS. 4 to 9, by forming recesses 15a and 15b at both ends of the piston 15 into which the extension side valve seat member 26 and the contraction side valve seat member 27 fit. Positioning of the extension-side valve seat member 26 and the contraction-side valve seat member 27 with respect to rotation around the axis can be reliably performed, and the assembly workability can be improved. As shown in FIGS. 7 to 9, the extension-side valve seat member 26 has a large diameter in which a side wall (cylindrical portion) of the opening abuts on the outer peripheral side of the extension-side communication passage 22 at one end of the piston 15. Part 30a,
And a small-diameter portion 30b contacting the inner peripheral side of the contraction-side communication passage 23.
And the contraction side communication passage 23 is directly connected to the cylinder lower chamber 13b. The bottom of the extension side valve seat member 26 is
An extension-side passage 31 having a diameter slightly smaller than the inner diameter of the cylinder 13 and communicating the extension-side chamber 26a with the cylinder lower chamber 13b is provided in the axial direction. An annular valve seat 32 is provided on the outer end surface of the bottom portion of the extension side valve seat member 26 on the inner and outer circumferences of the extension side passage 31, and the extension side disc valve is opposed to the valve seat 32.
33 is installed. Similarly, the contraction-side valve seat member 27 includes a large-diameter portion 34a in which the side wall (cylindrical portion) of the opening abuts on the outer peripheral side of the compression-side communication passage 23 at the other end of the piston 15, and an extension side. Combined with the small-diameter portion 34b that contacts the inner peripheral side of the communication passage 22, the contraction-side communication passage 23 communicates with the contraction-side chamber 27a, and the extension-side communication passage 22 directly communicates with the cylinder upper chamber 13a. It has become. The bottom of the contraction-side valve seat member 27 has a diameter slightly smaller than the inner diameter of the cylinder 13, and is provided with a contraction-side passage 35 communicating the contraction-side chamber 27a and the cylinder upper chamber 13a in the axial direction. An annular valve seat 36 is provided on the outer end surface of the bottom of the contraction-side valve seat member 27 on the inner and outer circumferences of the contraction-side passage 35 so as to protrude.
A contraction-side disc valve 37 is mounted so as to be opposed to. The operation of the first embodiment configured as described above will now be described. During the extension stroke of the piston rod 16, the contraction-side passage 35 is closed by the contraction-side disc valve 37,
The oil liquid on the cylinder upper chamber 13a side extends to the extension side communication passage 22, the extension side chamber.
26a and the extension side passage 31, and then the extension side disc valve 3
3 is opened to flow to the cylinder lower chamber 13b side, and a damping force is generated according to the degree of opening of the extension side disk valve 33. Also, during the contraction stroke, the extension-side passage is provided by the extension-side disc valve 33.
31 is closed, the oil liquid in the cylinder lower chamber 13b flows through the contraction-side communication passage 23, the contraction-side chamber 27a, and the contraction-side passage 35, opens the contraction-side disc valve 37, and flows toward the cylinder upper chamber 13a.
A damping force is generated in accordance with the degree of opening of the compression-side disk valve 37. At this time, the extension-side disc valves 33, 37
The valve is deflected by the pressure of the oil liquid and separated from the valve seats 32 and 36 to open at an opening degree corresponding to the pressure of the oil liquid. As a result, a damping force having a valve characteristic in which the damping force linearly increases in proportion to the increase in the piston speed is generated. And, the extension side communication passage 22, the extension side passage 31, and the disc valve 33,
Compression side communication passage 23, compression side passage 35, and disc valve 37
The damping force characteristics on the extension side and the contraction side can be set according to the above characteristics. Further, by providing the extension side valve seat member 26 and the contraction side valve seat member 27, the diameters of the valve seats 32, 36 and the extension side disk valves 33, 37 are increased, and the disk valves 32, 37 are provided. Can have a large pressure receiving area. The cylinder upper chamber 13a and the cylinder lower chamber 13b extend from the side chamber.
Since the communication is performed through the compression chamber 26a and the compression-side chamber 26b, the passage areas of the expansion-side communication path 22, the compression-side communication path 23, and the expansion-side paths 31, 35 can be made sufficiently large. This allows
The inclination of the damping force characteristics on the extension side and the contraction side can be reduced, and it becomes easy to set a low damping force. Further, the extension-side communication passage 22 and the contraction-side communication passage 23 of the piston 15, the extension-side passage 31 of the extension-side valve seat member 26,
In addition, since the compression-side passage 35 of the compression-side valve seat member 27 is provided along the axial direction, the piston 15, the extension-side valve seat member 26, and the compression-side valve seat member 27 are formed by sintering or the like. Since they can be molded at the same time, there is no need to perform separate processing, so that productivity can be improved and manufacturing costs can be reduced. Further, since the extension-side valve seat member 26 and the contraction-side valve seat member 27 can have the same shape, there is no need to prepare two types of parts. In the above embodiment, the extension-side communication passage 22, the contraction-side communication passage 23 of the piston 15, the extension-side passage 31 of the extension-side valve seat member 26, and the contraction-side passage 35 of the contraction-side valve seat member 27 Although they are elongated holes, these may be a plurality of round holes. Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the present invention is applied to a damping force adjustable hydraulic shock absorber capable of selecting different types of damping force characteristics on the extension side and the contraction side. Regarding the valve seat member, the contraction side valve seat member, the extension side and the contraction side disc valve,
Since the structure is the same as that of the first embodiment, the same reference numerals as in the first embodiment are used for the description. FIG. 10 is a vertical cross-sectional view taken along an orthogonal line passing through the extension-side communication passage and the compression-side communication passage of the piston, similarly to FIGS. 1 and 2. As shown in FIG. 10, the damping force-adjustable hydraulic shock absorber 38 includes an extension-side sub-valve on the extension-side valve seat member 26 and the contraction-side valve seat portion 27 provided at both ends of the piston 15. Seat member 39
And a contraction-side auxiliary valve seat member 40 are provided in an overlapping manner, and these are inserted through one end of the piston rod 41, and a nut 42 is screwed onto the distal end thereof to thereby form the piston rod 41.
Are connected integrally. A cylindrical guide portion 41a is formed at one end of the piston rod 41, and a cylindrical shutter 43 is rotatably fitted to the guide portion 41a. Shutter
An operation rod 44 is connected to 43, and the operation rod 44
Is inserted through the piston rod 41 and extended to the outside along the axis thereof, so that the shutter 43 can be rotated from the outside. In the shutter 43, there is an extension-side shutter chamber.
43a and a contraction-side shutter chamber 43b are formed. The extension side valve seat member is provided on the side wall of the guide portion 41a.
An extension side port 45 communicating with the extension side chamber 26a in the inside 26 and a port 46 communicating with the contraction side chamber 27a in the contraction side valve seat member 27 are provided. Further, the cylinder lower chamber 13b is provided through a passage 47 and an orifice 48 provided in the extension side sub-valve seat member 39.
And a port 52 communicating with the cylinder upper chamber 13a via a passage 50 provided in the contraction side sub-valve seat member 40 and an orifice 51. An extension-side opening communicating with the extension-side shutter chamber 43a is provided on the side wall of the shutter 43 so as to face the extension port 45.
The contraction side shutter chamber is opposed to 53 and the contraction side port 46.
A contraction-side opening 54 communicating with 43b is provided. Further, an opening 55 for constantly communicating the extension side shutter chamber 43a with the port 49 and an opening 56 for constantly communicating the contraction side shutter chamber 43b with the port 52 are provided. The extension-side opening 53 and the contraction-side opening 54 are formed in a substantially wedge shape, and the communication passage area between the extension-side opening 53 and the extension-side port depends on the rotational position of the shutter 43. When the (expansion-side communication passage area) is the maximum, the communication passage area (the compression-side communication passage area) between the contraction-side opening 54 and the contraction-side port 46 is minimized, and by rotating the shutter 43 to one side from this state. , The area of the extension side communication passage gradually decreases, and the area of the contraction side communication passage gradually increases,
When the extension side communication passage area is minimum, the contraction side communication passage area is maximum. The extension side sub-valve seat member 39 has a disk valve 57 (a check valve) for generating a damping force by permitting only the flow of the oil liquid from the passage 47 to the cylinder lower chamber 13b side, and an orifice.
A check valve 58 is provided which allows only the flow of the oil liquid from the cylinder chamber 48 to the cylinder lower chamber 13b side. Further, the contraction-side sub-valve seat member 40 has a disk valve 59 for generating a damping force by allowing only the flow of the oil liquid from the passage 50 to the cylinder upper chamber 13a side.
(A check valve) and a check valve 60 that allows only the flow of the oil liquid from the orifice 51 to the cylinder upper chamber 13a side. The disc valves 57 and 59 are connected to the extension-side valve seat member 26.
And extension-side disc valves 33, 37 of the compression-side valve seat member 27.
It is set to generate a smaller damping force. The extension side port 45 and the extension side opening 5
3, extension side shutter chamber 43a, opening 55, port 49, passage 4
7 and the orifice 48 constitute an extension side bypass passage, and the contraction side port 46, the contraction side opening 54, the contraction side shutter chamber 43b, the opening 56, the port 52, the passage 50 and the orifice 51 constitute a contraction side bypass passage. And
Further, the guide portion 41a and the shutter 43 constitute a damping force adjusting mechanism. In FIG. 7, reference numeral 61 denotes a thrust bearing for supporting the shutter 43, and reference numerals 62 and 63 denote an orifice and a reverse orifice for preventing the vertical movement of the shutter 43 by applying the positive pressure of the cylinder lower chamber 13b to the shutter 43. It is a stop valve. The operation of the second embodiment configured as described above will now be described. The arrow on the right side of the drawing in FIG. 7 indicates the flow of the oil liquid during the extension stroke of the piston rod 41, and the left arrow indicates the flow of the oil liquid during the contraction stroke. During the extension stroke of the piston rod 41, the contraction-side disk valves 37 and 59 and the check valve 60 are closed, and the oil liquid in the cylinder upper chamber 13a is discharged as shown by the right arrow in FIG. Open the extension side disc valve 33 through the passage 22 extension side chamber 26a and the extension side passage 31 to open the cylinder lower chamber 13b.
The disk valve 57 flows from the expansion side chamber 26a to the expansion side port 45, the expansion side opening 53, the expansion side shutter chamber 43a, the opening 55, the port 49, the passage 47, and the orifice 48 which are expansion side bypass passages. And the check valve 58 is opened to flow to the cylinder lower chamber 13b side. At this time, a damping force is generated in accordance with the opening degree of the orifice 48 and the extension side disk valves 33 and 57, and the damping force is generated by changing the communication passage area between the extension side opening 53 and the port 45 by the rotation of the shutter 43. Can be adjusted. During the compression stroke of the piston rod 41, the extension-side disc valves 33, 57 and the check valve 58 are closed, and the oil liquid in the cylinder lower chamber 13b is supplied as shown by the left arrow in FIG.
The compression-side disc valve 37 is opened through the compression-side communication passage 23, the compression-side chamber 27a, and the compression-side passage 35 to open the cylinder upper chamber 13a, and flows from the compression-side chamber 27a to the compression-side bypass passage port 46, the compression-side opening. Part 54, contraction side shutter chamber 43
b, through the opening 56, the port 52, the passage 50 and the orifice 51, the disc valve 59 and the check valve 60 are opened to flow toward the cylinder upper chamber 13a. At this time, a damping force is generated according to the opening degree of the orifice 51 and the contraction-side disk valves 37 and 59, and the rotation of the shutter 43 causes the contraction-side opening 54 and the port 46 to rotate.
The damping force can be adjusted by changing the area of the communication path with the damper. Then, the shutter 43 is rotated by operating the operation rod 44 from the outside, and the extension opening 53 and the extension port
By maximizing the area of the communication path with the extension 45 (area of the expansion side communication path) and minimizing the area of the communication path between the compression side opening 54 and the compression side port 46 (area of the compression side communication path), damping on the extension side is achieved. The force becomes the minimum (soft characteristic) and the damping force on the compression side becomes the maximum (hard characteristic). When the shutter 43 is rotated to one side from this state to gradually reduce the extension-side communication passage area and gradually increase the compression-side communication passage area, the expansion-side damping force gradually increases and the contraction-side damping force increases. Gradually become smaller. Then, by minimizing the area of the expansion side communication path and maximizing the area of the compression side communication path, the expansion side damping force becomes maximum (hard characteristic) and the contraction side damping force becomes minimum (soft characteristic). In this way, the damping force characteristics on the extension side and the contraction side can be selected to be different in size and can be continuously adjusted. As in the first embodiment, the inclination of the damping force characteristic can be set small, and the number of processing steps can be reduced to improve the productivity and reduce the manufacturing cost.
Further, the piston 15, the extension-side valve seat member 26, and the compression-side valve seat member 27 can be shared with the type in which the damping force is not adjusted as shown in the first embodiment, and is provided on the side wall of the guide portion 41a of the piston rod 41. Since the extension side and the contraction side bypass passages can be easily formed only by providing the ports 45 and 46, the number of parts can be reduced and the manufacturing cost can be reduced. As described above in detail, according to the hydraulic shock absorber of the present invention, during the extension stroke of the piston rod, the oil in the cylinder flows through the extension side communication passage due to the sliding of the piston. The damping force is generated by the extension side disc valve,
During the contraction stroke, the oil in the cylinder flows through the contraction side communication passage due to the sliding of the piston, and a damping force is generated by the contraction side disk valve. At this time, since the extension-side and compression-side valve seat members are provided, the diameters of the extension-side and compression-side disc valves can be increased. Since the two chambers in the cylinder communicate with each other through the cylindrical portion of the seat member, it is possible to increase the passage area of the oil liquid in the extending stroke and the contracting stroke. As a result, the inclination of the damping force characteristics on the extension side and the contraction side can be reduced, and it becomes easy to set a low damping force. Further, since the extension side communication path and the contraction side communication path of the piston are provided along the axial direction, it is possible to easily mold, improve productivity and reduce manufacturing cost. To play.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view taken along an orthogonal line passing through an extension communication path and a compression communication path of a main part of a first embodiment of the present invention. FIG. 2 is a vertical cross-sectional view taken along an orthogonal line passing through an extension communication path and a compression communication path of the hydraulic shock absorber in FIG. FIG. 3 is an exploded perspective view showing a part of a piston, an extension side valve seat member, and a contraction side valve seat member of the apparatus of FIG. FIG. 4 is a side longitudinal sectional view of another embodiment of the piston of the apparatus of FIG. 1; FIG. 5 is a plan view of the piston of FIG. 4; FIG. 6 is a bottom view of the piston of FIG. 4; 7 is a longitudinal sectional view of the extension side valve seat member of the apparatus of FIG. 1 taken along the line AA of FIG. 8; FIG. 8 is a plan view of the extension side valve seat member of FIG. 7; FIG. 9 is a bottom view of the extension side valve seat member of FIG. 7; FIG. 10 is a vertical sectional view of a side surface of a main part of the second embodiment of the present invention, taken along the same orthogonal line as in FIG. 1; FIG. 11 is a side view of a piston portion of a conventional hydraulic shock absorber.
It is a longitudinal cross-sectional view by CC line. FIG. 12 is a transverse sectional view taken along line BB of FIG. 11; [Explanation of Signs] 12 Hydraulic shock absorber 13 Cylinder 15 Piston 16 Piston rod 22 Extension side communication path 23 Retraction side communication path 26 Extension side valve seat member 27 Retraction side valve seat member 33 Extension side disc valve 37 Retraction side disc valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16F 9/348 B60G 17/08

Claims (1)

(57) [Claim 1] A cylinder filled with an oil liquid, a cylindrical piston slidably fitted in the cylinder and defining two chambers in the cylinder, A piston rod having one end penetrating the piston and the other end extending to the outside of the cylinder; An extension-side communication passage, a pair of contraction-side communication passages drilled along the axial direction at positions opposed to each other with the piston rod interposed between the pair of extension-side communication passages of the piston; One end of the cylindrical portion surrounds the piston rod and the pair of extension side communication passages and abuts on one end surface of the piston so as not to surround the pair of contraction side communication passages, and the other end of the cylinder portion serves as a valve seat. Extension side valve seat member, and extension side valve seat portion An extension-side disc valve provided at the other end of the cylinder so as to close the cylinder, and a cylinder, one end of the cylinder surrounding the piston rod and the pair of compression-side communication passages. A contraction-side valve seat member that abuts against the other end surface of the piston so as not to surround the extension-side communication passage, and the other end of the cylinder portion serves as a valve seat, and the cylinder provided on the other end side of the compression-side valve seat member. A hydraulic shock absorber comprising: a disc valve provided so as to close a portion.