Hydraulic shock absorber

Abstract

To provide a hydraulic shock absorber capable of suppressing damages generated in a seal member.SOLUTION: A hydraulic shock absorber is equipped with a cylindrical outer cylinder 16, a cylindrical inner cylinder 15 that is inserted in the outer cylinder 16 and forms a reservoir chamber 18 between the outer cylinder 16 and the inner cylinder 15, a rod 50 that is inserted in the inner cylinder 15, a seal member 41 that has a lip 102 extending to the axially inner side and seals a space between the rod 50 and the outer cylinder 16, and a rod guide 26 that is inserted in the axially inner side than the seal member 41 in the inner cylinder 15 and in which the rod 50 is inserted. The rod guide 26 has a recessed portion 143 opposing to the lip 102, and a communication path 151 that has components toward the axially inner side, and performs communication between a bottom surface 143a of the recessed portion 143 and the reservoir chamber 18.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hydraulic shock absorber. [Background technology]

[0002] A double-tube shock absorber having a recess for collecting foreign matter, so-called contamination (hereinafter referred to as "contamination") has been disclosed (see, for example, Patent Document 1). Also, a sealing device having a filter provided between a check lip and a reservoir chamber has been disclosed (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-32079 [Patent Document 2] Japanese Patent Application Publication No. 2019-27547 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a concern that contaminants accumulated around the seal member may infiltrate the sliding portion of the seal member, causing damage to the seal member.

[0005] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic shock absorber that can suppress damage to the sealing member. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, one aspect of the present invention comprises a cylindrical outer tube, a cylindrical inner tube inserted into the outer tube and forming a reservoir chamber between the outer tube and the inner tube, a rod inserted into the inner tube, a sealing member having a lip extending axially inward and sealing between the rod and the outer tube, and a rod guide inserted axially inward into the inner tube than the sealing member and into which the rod is inserted, wherein the rod guide has a recess facing the lip and a communication passage having a component directed axially inward and connecting the bottom surface of the recess to the reservoir chamber. [Effects of the Invention]

[0007] According to the present invention, damage to the sealing member can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a hydraulic shock absorber according to a first embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing a main part of a hydraulic shock absorber according to a first embodiment of the present invention. [Figure 3] FIG. 4 is a cross-sectional view showing a main part of a hydraulic shock absorber according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view showing a main part of a hydraulic shock absorber according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing a main part of a hydraulic shock absorber according to a fourth embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view showing a main part of a hydraulic shock absorber according to a fifth embodiment of the present invention. [Figure 7] FIG. 10 is a cross-sectional view showing a main part of a hydraulic shock absorber according to a sixth embodiment of the present invention. [Figure 8] FIG. 10 is a cross-sectional view showing a main part of a hydraulic shock absorber according to a seventh embodiment of the present invention. [Figure 9] FIG. 13 is a cross-sectional view showing a main part of a hydraulic shock absorber according to an eighth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0010] First, a hydraulic shock absorber 11 according to a first embodiment will be described with reference to FIGS. 1 is a shock absorber used in a suspension device of a vehicle such as an automobile or a railroad car. Specifically, the shock absorber 11 is a shock absorber used in a suspension device of an automobile. The hydraulic shock absorber 11 includes a cylinder 17 having an inner cylinder 15 and an outer cylinder 16 . The inner cylinder 15 is tubular, specifically cylindrical.

[0011] The outer cylinder 16 is cylindrical, specifically, cylindrical with a bottom. The inner cylinder 15 is inserted radially inside the outer cylinder 16. A reservoir chamber 18 is formed between the outer cylinder 16 and the inner cylinder 15. In other words, the reservoir chamber 18 is formed between the inner cylinder 15 and the outer cylinder 16. The outer cylinder 16 has a body 21 and a bottom 22. The body 21 is tubular, specifically cylindrical. The bottom 22 is disk-shaped, and closes one axial end of the body 21. The other end of the body 21 opposite the bottom 22 forms an opening 23. The inner cylinder 15 is a one-piece molded product made of a single piece of metal.

[0012] The hydraulic shock absorber 11 has a valve body 25 and a rod guide 26. The valve body 25 is annular and is provided at one axial end of the inner cylinder 15. The valve body 25 is placed on the bottom 22 of the outer cylinder 16. The rod guide 26 is annular and is provided at the other axial end of the inner cylinder 15 and the outer cylinder 16 on the opposite side from the valve body 25. The valve body 25 constitutes a base valve 30.

[0013] One axial end of the inner cylinder 15 is fitted into a valve body 25. The inner cylinder 15 is placed on the bottom 22 of the outer cylinder 16 via the valve body 25. The other axial end of the inner cylinder 15 is fitted into a rod guide 26. The inner cylinder 15 is fitted into the body 21 of the outer cylinder 16 via the rod guide 26. In this state, the inner cylinder 15 is positioned radially relative to the outer cylinder 16. A passage groove 35 is formed in the valve body 25. The valve body 25 and the bottom 22 communicate with each other via the passage groove 35. The space between the valve body 25 and the bottom 22, like the space between the inner cylinder 15 and the outer cylinder 16, forms a reservoir chamber 18.

[0014] The hydraulic shock absorber 11 has a seal member 41. The seal member 41 is annular and is located closer to the opening 23 of the outer cylinder 16 than the rod guide 26. Here, in the axial direction of the cylinder 17, the bottom 22 side near the opening 23 is defined as the inner side in the cylinder's internal / external direction, and the side opposite the bottom 22 is defined as the outer side in the cylinder's internal / external direction. The seal member 41 is located further outward than the rod guide 26 in the cylinder's internal / external direction. Like the rod guide 26, the seal member 41 is fitted to the inner periphery of the body portion 21. A locking portion 43 is formed at the end of the body portion 21 on the opening 23 side. The locking portion 43 is formed by plastically deforming the body portion 21 radially inward by crimping, such as curling. The seal member 41 is sandwiched between the locking portion 43 and the rod guide 26. The seal member 41 closes the opening 23 of the outer cylinder 16. Specifically, the seal member 41 is an oil seal. The rod guide 26 is inserted into the inner cylinder 15 further inward than the seal member 41 in the cylinder inward / outward direction, that is, further inward in the axial direction of the inner cylinder 15 .

[0015] The hydraulic shock absorber 11 has a piston 45. The piston 45 is slidably fitted within the inner cylinder 15. The piston 45 divides the inner cylinder 15 into two chambers: a first chamber 48 and a second chamber 49. The first chamber 48 is the portion between the piston 45 and the rod guide 26 within the inner cylinder 15. The second chamber 49 is the portion between the piston 45 and the valve body 25 within the inner cylinder 15. The second chamber 49 is separated from the reservoir chamber 18 by the valve body 25. The first chamber 48 and the second chamber 49 are filled with oil L as a working fluid. The reservoir chamber 18 is filled with gas G and oil L as working fluids.

[0016] The hydraulic shock absorber 11 has a rod 50. The rod 50 is inserted into the inner cylinder 15, and one axial end of the rod 50 is connected to the piston 45. The axial end of the rod 50 opposite the piston 45 extends from the inner cylinder 15 and outer cylinder 16 of the cylinder 17 to the outside via the opening 23. The piston 45 is connected to the rod 50 by a nut 51.

[0017] The rod 50 is made of metal and has a main shaft portion 55, a mounting shaft portion 56, and a threaded shaft portion 57. The main shaft portion 55 is cylindrical. The outer circumferential surface of the main shaft portion 55 is a cylindrical surface. The mounting shaft portion 56 is also cylindrical, and its outer diameter is smaller than that of the main shaft portion 55. A male thread 61 is formed on the outer circumferential portion of the mounting shaft portion 56 on the opposite side of the main shaft portion 55 in the axial direction. The piston 45 is fitted onto the mounting shaft portion 56. The nut 51 is threaded onto the male thread 61 of the mounting shaft portion 56.

[0018] The rod 50 extends at its main shaft portion 55 from the inner cylinder 15 and the outer cylinder 16 to the outside through the rod guide 26 and the seal member 41. In other words, the main shaft portion 55 of the rod 50 is inserted into the rod guide 26 and the seal member 41. One axial end of the rod 50 is disposed inside the outer cylinder 16 and the inner cylinder 15, and the other axial end is disposed outside the outer cylinder 16 and the inner cylinder 15. The main shaft portion 55 of the rod 50 is in sliding contact with the rod guide 26 at its outer peripheral surface. The rod 50 is guided by the rod guide 26 and moves axially relative to the inner cylinder 15 and the outer cylinder 16 together with the piston 45. The main shaft portion 55 of the rod 50 is in sliding contact with the seal member 41 at its outer peripheral surface. The seal member 41 seals between the outer cylinder 16 and the rod 50. The seal member 41 prevents the oil L in the inner cylinder 15 and the oil L and gas G in the reservoir chamber 18 from leaking out to the outside. The rod 50 has a threaded shaft portion 57 at a portion that protrudes outward from the cylinder 17 and the seal member 41.

[0019] A passage 65 and a passage 66 are formed in the piston 45. The passages 65, 66 pass through the piston 45 in the axial direction of the piston 45. The passages 65, 66 can communicate between the first chamber 48 and the second chamber 49. The hydraulic shock absorber 11 has a disc valve 67. The disc valve 67 is provided on the side of the piston 45 opposite the bottom 22 in the axial direction. The disc valve 67 is annular, and closes the passage 65 by abutting against the piston 45. The hydraulic shock absorber 11 has a disc valve 68. The disc valve 68 is provided on the bottom 22 side of the piston 45 in the axial direction. The disc valve 68 is annular, and closes the passage 66 by abutting against the piston 45.

[0020] The direction in which the rod 50 increases its amount of penetration into the inner cylinder 15 and the outer cylinder 16 is the compression side. When the rod 50 moves toward the compression side, the piston 45 moves in a direction that narrows the second chamber 49. As a result, when the pressure in the second chamber 49 becomes higher than the pressure in the first chamber 48 by a predetermined value or more, the disc valve 67 opens the passage 65, allowing the oil L in the second chamber 49 to flow into the first chamber 48. At that time, the disc valve 67 generates a damping force.

[0021] The direction in which the rod 50 increases the amount of protrusion from the inner cylinder 15 and the outer cylinder 16 is defined as the extension side. When the rod 50 moves in the extension side, the piston 45 moves in a direction that narrows the first chamber 48. As a result, when the pressure in the first chamber 48 becomes higher than the pressure in the second chamber 49 by a predetermined value or more, the disc valve 68 opens the passage 66, allowing the oil L in the first chamber 48 to flow into the second chamber 49. At that time, the disc valve 68 generates a damping force.

[0022] A fixed orifice (not shown) is formed in at least one of the piston 45 and the disc valve 67. This fixed orifice allows communication between the first chamber 48 and the second chamber 49 via the passage 65 even when the disc valve 67 is in a state where the passage 65 is most closed by the disc valve 67. In addition, a fixed orifice (not shown) is formed in at least one of the piston 45 and the disc valve 68. This fixed orifice allows communication between the first chamber 48 and the second chamber 49 via the passage 66 even when the disc valve 68 is in a state where the passage 66 is most closed by the disc valve 68.

[0023] The valve body 25 is formed with a fluid passage 71 and a fluid passage 72. The fluid passages 71, 72 pass through the valve body 25 in the axial direction of the valve body 25. The fluid passages 71, 72 can connect the second chamber 49 and the reservoir chamber 18 to each other. The base valve 30 includes a disc valve 75 , a disc valve 76 , and a pin member 78 . A pin member 78 attaches the disc valve 75 and the disc valve 76 to the valve body 25 .

[0024] The disc valve 75 is provided on the bottom 22 side in the axial direction of the valve body 25. The disc valve 75 is annular, and closes the liquid passage 71 by abutting against the valve body 25. The disc valve 76 is provided on the opposite side of the valve body 25 in the axial direction from the bottom portion 22. The disc valve 76 is annular, and closes the liquid passage 72 by abutting against the valve body 25. The base valve 30 divides the interior of the cylinder 17 into two chambers: a second chamber 49 and a reservoir chamber 18 .

[0025] As the rod 50 moves toward the compression side, the piston 45 moves in a direction that narrows the second chamber 49. As a result, when the pressure in the second chamber 49 becomes higher than the pressure in the reservoir chamber 18 by a predetermined value or more, the disc valve 75 of the base valve 30 opens the fluid passage 71, allowing the hydraulic fluid L in the second chamber 49 to flow into the reservoir chamber 18. At this time, the disc valve 75 generates a damping force. As the rod 50 moves toward the extension side, the piston 45 moves toward the first chamber 48. As a result, when the pressure in the second chamber 49 becomes lower than the pressure in the reservoir chamber 18, the disc valve 76 of the base valve 30 opens the fluid passage 72, allowing the hydraulic fluid L in the reservoir chamber 18 to flow into the second chamber 49. At this time, the disc valve 76 allows the hydraulic fluid L to flow from the reservoir chamber 18 into the second chamber 49 without generating any substantial damping force. The disc valve 76 is a suction valve.

[0026] The hydraulic shock absorber 11 has a rod 50 arranged at the top and connected to the vehicle body side, and a cylinder 17 arranged at the bottom and connected to the vehicle wheel side, generating a damping force against movement of the wheel relative to the vehicle body.

[0027] 2, the outer periphery of seal member 41 is fitted into the end of opening 23 side of barrel 21 of outer cylinder 16, and the inner periphery is pressed against the outer periphery of main shaft portion 55 of rod 50. Seal member 41 seals between main shaft portion 55 of rod 50 and outer cylinder 16. The seal member 41 has a seal body 91, a spring 92, and another spring 93. The seal body 91 is an integrally molded product consisting of an elastic seal portion 95 and an annular member 96. The elastic seal portion 95 is made of an elastic rubber material with good sliding properties, such as nitrile rubber or fluororubber. The annular member 96 is made of metal and has a circular ring shape, and is embedded within the elastic seal portion 95. The annular member 96 maintains the shape of the elastic seal portion 95 and provides the strength to secure the seal member 41 to the outer tube 16 and the rod guide 26.

[0028] The elastic seal portion 95 has a dust lip 101 , a main lip 102 (lip), an inner peripheral covering portion 103 , an outer peripheral seal portion 104 , and an inner seal portion 105 . The dust lip 101 is located radially inside the seal member 41 and extends outward in the cylinder inward / outward direction from the inner circumferential side of the annular member 96. The dust lip 101 is in the shape of a circular ring tube and is pressed against the outer circumferential surface of the main shaft portion 55 of the rod 50. The dust lip 101 is generally in the shape of a tapered tube whose inner diameter decreases as it moves away from the annular member 96 outward in the cylinder inward / outward direction.

[0029] The main lip 102 is located radially inside the seal member 41 and extends inward in the cylinder inward / outward direction from the inner circumferential side of the annular member 96. The main lip 102 has an annular cylindrical shape and is pressed against the outer circumferential surface of the main shaft portion 55 of the rod 50. The main lip 102 has an overall tapered cylindrical shape with an inner diameter that decreases as it moves away from the annular member 96 inward in the cylinder inward / outward direction.

[0030] The inner circumferential covering portion 103 covers the inner circumferential surface of the annular member 96 and connects the dust lip 101 and the main lip 102. There is a radial gap between the inner circumferential covering portion 103 and the outer circumferential surface of the main shaft portion 55 of the rod 50. The outer circumferential seal portion 104 covers the outer circumferential surface of the annular member 96 and is fitted to the inner circumferential surface of the body portion 21 of the outer cylinder 16 to seal the gap with the outer cylinder 16 . The inner seal portion 105 covers the inner end face of the annular member 96 in the cylinder inward and outward direction, and comes into close contact with the rod guide 26 to seal the gap between the rod guide 26 and itself.

[0031] The spring 92 is a metal annular garter spring, and is fitted onto the outer periphery of the dust lip 101 . The spring 93 is a metal annular garter spring, and is fitted onto the outer periphery of the main lip 102 .

[0032] The dust lip 101 of the seal member 41 is disposed on the outside, i.e., on the atmospheric side, in the cylinder inward / outward direction, and the main lip 102 is disposed on the inside, in the cylinder inward / outward direction. The seal member 41 has its annular member 96 positioned radially thereon sandwiched between the rod guide 26 and the crimped locking portion 43 of the outer cylinder 16. At this time, the outer peripheral seal portion 104 of the seal member 41 comes into sealing contact with the inner peripheral portion of the body portion 21 of the outer cylinder 16. Also, at this time, the inner seal portion 105 of the seal member 41 comes into sealing contact with the outer end of the rod guide 26 in the cylinder inward / outward direction. The seal member 41 is fixed to the cylinder 17 by being sandwiched between the rod guide 26 and the locking portion 43 of the cylinder 17.

[0033] When the seal member 41 is attached to the cylinder 17, the main shaft portion 55 of the rod 50 is inserted inside the dust lip 101 and the main lip 102. In this state, one end of the rod 50 protrudes from one end of the cylinder 17. In this state, the dust lip 101 is provided on the end side of the cylinder 17 from which the rod 50 protrudes, and the main lip 102 is provided inside the dust lip 101 in the cylinder interior / exterior direction.

[0034] The spring 92 fitted to the outer periphery of the dust lip 101 is used to maintain a constant tightening force in the direction in which the dust lip 101 contacts the rod 50. The spring 92 is also used to adjust the tightening force to satisfy the design specifications of the dust lip 101. The spring 93 fitted to the outer periphery of the main lip 102 adjusts the tightening force in the direction in which the main lip 102 contacts the rod 50.

[0035] The seal member 41 maintains its airtightness by the dust lip 101 tightly contacting the rod 50 due to its interference and the tension force of the spring 92. When the rod 50 is exposed further outward in the cylinder than the seal member 41, the dust lip 101 prevents foreign matter adhering to the rod 50 from entering inward in the cylinder. The main lip 102 also adheres to the rod 50 due to its interference and the tension of the spring 93, maintaining a tight seal. A chamber 108 is formed between the seal member 41 and the rod guide 26. The main lip 102 extends toward this chamber 108 from the inner peripheral covering portion 103 and the inner seal portion 105. The main lip 102 scrapes off oil L from the rod 50 that adheres to the rod 50 and passes from the first chamber 48 over the rod guide 26 into the chamber 108 when the rod 50 moves toward the extension side, thereby restricting leakage to the outside. The oil L scraped off from the rod 50 by the main lip 102 when the rod 50 moves toward the extension side remains in the chamber 108 without passing over the main lip 102.

[0036] The rod guide 26 has a rod guide body 111 and a collar 112 . The rod guide main body 111 is made of metal and has a stepped cylindrical shape. An end face 111a at one end in the axial direction of the rod guide main body 111 and an end face 111b at the other end in the axial direction are flat and perpendicular to the central axis of the rod guide main body 111. The end face 111a is located at the outer end of the rod guide main body 111 in the cylinder's inner and outer directions, and the end face 111b is located at the inner end of the rod guide main body 111 in the cylinder's inner and outer directions.

[0037] The rod guide body 111 has a large outer diameter portion 121, a small outer diameter portion 122, and a step portion 123 on its outer periphery. The large-diameter outer diameter portion 121 is provided on the outer periphery of the rod guide main body 111 on the side of the end face 111a in the axial direction. The small outer diameter portion 122 is provided on the end face 111b side in the axial direction of the outer periphery of the rod guide main body 111. The small outer diameter portion 122 has an outer diameter smaller than the outer diameter of the large outer diameter portion 121.

[0038] The step portion 123 connects the axial edge of the large-diameter outer diameter portion 121 on the side of the small-diameter outer diameter portion 122 to the axial edge of the small-diameter outer diameter portion 122 on the side of the large-diameter outer diameter portion 121. The step portion 123 extends approximately perpendicular to the central axis of the rod guide main body 111, and has an inner surface portion 123a and an outer surface portion 123b. The inner surface portion 123a is located more inward than the outer surface portion 123b in the radial direction of the rod guide main body 111. The inner surface portion 123a has a flat shape that extends perpendicular to the central axis of the rod guide main body 111. The outer surface portion 123b extends radially outward from the outer peripheral edge of the inner surface portion 123a. The outer surface portion 123b is tapered. The outer surface portion 123b approaches the end face 111a of the rod guide main body 111 in the axial direction as it moves away from the inner surface portion 123a in the radial direction.

[0039] The rod guide 26 has a rod guide main body 111 that fits into the inner periphery of the barrel 21 of the outer cylinder 16 at its large-diameter outer diameter portion 121 and fits into the inner periphery of the inner cylinder 15 at its small-diameter outer diameter portion 122. This fixes the rod guide main body 111 to the cylinder 17. At this time, the inner surface portion 123a of the rod guide main body 111 abuts against the outer end of the inner cylinder 15 in the cylinder interior / exterior direction. The end face 111a of the rod guide main body 111 abuts against the inner seal portion 105 of the seal member 41. The end face 111b of the rod guide main body 111 forms the first chamber 48. The inner surface portion 123a and the outer surface portion 123b of the rod guide main body 111 form the reservoir chamber 18.

[0040] A through hole 131 that passes through the rod guide body 111 in the axial direction is formed in the radial center of the rod guide body 111. The through hole 131 has a large diameter hole portion 132, a small diameter hole portion 133, and a medium diameter hole portion 134. The large diameter hole portion 132 is provided at the end of the through hole 131 on the end face 111 a side in the axial direction of the rod guide body 111 . The medium diameter hole portion 134 is provided on the opposite side of the end face 111a from the large diameter hole portion 132 of the through hole 131 in the axial direction of the rod guide main body 111. The medium diameter hole portion 134 is provided at the end of the through hole 131 on the end face 111b side in the axial direction of the rod guide main body 111. The medium diameter hole portion 134 has an inner diameter smaller than the inner diameter of the large diameter hole portion 132. The small diameter hole portion 133 is provided between the large diameter hole portion 132 and the medium diameter hole portion 134 of the through hole 131 in the axial direction of the rod guide main body 111. The small diameter hole portion 133 has an inner diameter slightly smaller than the inner diameter of the medium diameter hole portion 134.

[0041] The large diameter hole portion 132 of the rod guide body 111 has a hole inner peripheral portion 141 , a hole step portion 142 , and a recess 143 . The hole inner peripheral portion 141 has an inner peripheral surface 141a that extends from the inner peripheral edge of the end face 111a toward the end face 111b in the axial direction of the rod guide main body 111. The diameter of the inner peripheral surface 141a decreases as it approaches the end face 111b in the axial direction of the rod guide main body 111. The inner peripheral surface 141a has a curved cross section in a plane including the central axis of the rod guide main body 111. The inner peripheral surface 141a forms a chamber 108.

[0042] The hole step portion 142 has a step surface 142a that extends radially outward from the edge of the small diameter hole portion 133 on the opposite side of the medium diameter hole portion 134 in the axial direction of the rod guide main body 111. The step surface 142a is a tapered surface. The step surface 142a is inclined so that the radially outward direction the step surface 142a approaches the end face 111b in the axial direction of the rod guide main body 111. The step surface 142a forms a chamber 108.

[0043] The recess 143 is located outside the step surface 142a and inside the inner circumferential surface 141a in the radial direction of the rod guide main body 111. The recess 143 is recessed from the step surface 142a toward the end face 111b in the axial direction of the rod guide main body 111. The recess 143 has an annular shape coaxial with the inner circumferential surface 141a. The bottom surface 143a of the recess 143 connects the inner circumferential edge of the step surface 142a to the axial edge of the inner circumferential surface 141a on the side of the end face 111b. The cross section of the bottom surface 143a in a plane including the central axis of the rod guide main body 111 is arc-shaped. The radial width of the recess 143 decreases as the depth increases. The bottom surface 143a is a curved surface that is continuous with the inner circumferential surface 141a. The cross section of the recess 143 in a plane including the central axis of the rod guide main body 111 may be angular. In the radial direction of the rod guide main body 111, the entire bottom surface 143a of the recess 143 is located more inward than the inner side surface 123a of the step portion 123. In the axial direction of the rod guide main body 111, the entire bottom surface 143a of the recess 143 is located closer to the end face 111a than the inner side surface 123a of the step portion 123. The bottom surface 143a forms a chamber 108.

[0044] The rod guide main body 111 has a communication passage 151 that connects the recess 143 and the step portion 123. One end of the communication passage 151 opens to the bottom surface 143a of the recess 143, including the deepest position of the bottom surface 143a. The other end of the communication passage 151 opens to a portion of the inner surface portion 123a of the step portion 123 that is radially outward of the inner cylinder 15. Therefore, the communication passage 151 connects the bottom surface 143a of the recess 143 to the reservoir chamber 18.

[0045] Here, in the axial direction of the rod guide main body 111, the inner surface portion 123a of the step portion 123 is closer to the end face 111b than the bottom surface 143a of the recess 143. Therefore, the communicating passage 151 has a component that is directed inward in the cylinder inward / outward direction of the rod guide 26, in other words, inward in the axial direction of the cylinder 17. The communicating passage 151 is linear, and the more outward in the radial direction of the rod guide main body 111, the more inward in the cylinder inward / outward direction of the rod guide main body 111. The communicating passage 151 extends in the direction of an extension of the step surface 142a. In other words, the angle of the communicating passage 151 with respect to the central axis of the rod guide main body 111 is equal to the angle of the step surface 142a with respect to the central axis of the rod guide main body 111. Note that the angle of the communicating passage 151 with respect to the central axis of the rod guide main body 111 may be different from the angle of the step surface 142a with respect to the central axis of the rod guide main body 111.

[0046] A plurality of such communication passages 151 are provided at equal intervals around the circumferential direction of the rod guide main body 111. All of the communication passages 151 provided in the rod guide main body 111 communicate between the bottom surface 143a of the recess 143 and the reservoir chamber 18. The plurality of communication passages 151 are arranged so that one of them opens at the vertically lowest position of the bottom surface 143a of the hydraulic shock absorber 11 when attached to the vehicle. Furthermore, when the hydraulic shock absorber 11 is attached to the vehicle, at least one of the plurality of communication passages 151 located at the lowermost position in the vertical direction is inclined so as to be positioned vertically downward as it approaches the reservoir chamber 18. Note that only one communication passage 151 may be provided for the rod guide main body 111. Even in this case, this communication passage 151 opens at the vertically lowest position of the bottom surface 143a of the hydraulic shock absorber 11 when attached to the vehicle, and is inclined so as to be positioned vertically downward as it approaches the reservoir chamber 18.

[0047] The main lip 102 of the seal member 41 fits into the large-diameter hole portion 132. The seal member 41 forms the chamber 108 between the large-diameter hole portion 132 and the small-diameter hole portion 133 of the rod guide 26. The main lip 102 of the seal member 41 is on the chamber 108 side. When the rod 50 moves in the extension direction, increasing the amount of extension of the rod 50 from the seal member 41, the main lip 102 scrapes off oil L adhering to the rod 50. This oil L then remains in the chamber 108. The chamber 108 is in communication with the reservoir chamber 18 via a communication passage 151. Therefore, the oil L remaining in the chamber 108 is discharged by gravity into the reservoir chamber 18 via the communication passage 151. The main lip 102 of the seal member 41 faces the step surface 142a of the hole step portion 142 and the bottom surface 143a of the recess 143 in the axial direction of the rod guide main body 111. In other words, the recess 143 faces the main lip 102 in the axial direction of the rod guide body 111.

[0048] The collar 112 is cylindrical and is fitted and fixed in the medium diameter hole 134 of the rod guide main body 111. The collar 112 is formed by coating the inner periphery of a metal cylinder made of SPCC, SPCE, or the like with fluororesin-impregnated bronze. In the rod guide 26, the rod 50 is inserted into the collar 112 so that it makes sliding contact with the outer circumferential surface of the main shaft portion 55.

[0049] The aforementioned Patent Document 1 discloses a twin-tube shock absorber having a recess for collecting contaminants. Contaminants collected in the recess around the seal member may infiltrate the sliding portion of the seal member. This raises concerns that the contaminants may cause damage to the seal member.

[0050] Contamination that occurs in the hydraulic shock absorber 11 of the first embodiment includes, for example, the rod 50 repeatedly sliding against the collar 112 of the rod guide 26, causing the rod 50 to become detached from the collar 112. Such contamination is discharged into the chamber 108 between the seal member 41 and the rod guide 26 together with the oil liquid L adhering to the rod 50, as shown by the dashed arrow in Fig. 2. The contaminants thus discharged into the chamber 108 together with the oil liquid L move by gravity along the step surface 142a of the hole step portion 142 together with the oil liquid L, or within the oil liquid L, and reach the bottom surface 143a of the recess 143.

[0051] In the hydraulic shock absorber 11 of the first embodiment, the rod guide 26 is provided with a communication passage 151 that has a component directed inward in the axial direction of the cylinder 17 and that communicates the bottom surface 143a of the recess 143 with the reservoir chamber 18. Therefore, in the hydraulic shock absorber 11, contaminants that have reached the bottom surface 143a of the recess 143 can be discharged from the bottom surface 143a through the communication passage 151 to the reservoir chamber 18 together with the oil L by gravity or the like. Therefore, the hydraulic shock absorber 11 can suppress damage to the seal member 41. If the main lip 102 of the seal member 41 is damaged, the ability of the main lip 102 to scrape off the oil L will be reduced, and the oil L, together with the rod 50, may leak outward in the cylinder inward and outward direction beyond the main lip 102. The hydraulic shock absorber 11 can suppress such a situation.

[0052] [Second embodiment] Next, the second embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 3. Note that parts common to the first embodiment will be designated by the same names and symbols. The hydraulic shock absorber 11A of the second embodiment has a rod guide 26A that is partially different from the rod guide 26 instead of the rod guide 26. The rod guide 26A has a rod guide main body 111A that is partially different from the rod guide main body 111 instead of the rod guide main body 111. The rod guide main body 111A has a through hole 131A that is partially different in shape from the through hole 131 formed in place of the through hole 131. The through hole 131A has a large diameter hole portion 132A that is partially different in shape from the large diameter hole portion 132 instead of the large diameter hole portion 132.

[0053] The large diameter hole portion 132A has a hole inner peripheral portion 141A, a hole step portion 142A, and a recess 143A. The hole inner peripheral portion 141A has an inner peripheral surface 141Aa that extends from the inner peripheral edge of the end face 111a toward the end face 111b in the axial direction of the rod guide main body 111A. The inner peripheral surface 141Aa is a tapered surface, and its diameter decreases toward the end face 111b in the axial direction of the rod guide main body 111A. The inner peripheral surface 141Aa forms a chamber 108.

[0054] The hole step portion 142A has a step surface 142Aa that extends radially outward from the edge of the small diameter hole portion 133 opposite the medium diameter hole portion 134 in the axial direction of the rod guide main body 111A. The step surface 142Aa is tapered. The step surface 142Aa is inclined so that it approaches the end face 111b in the axial direction of the rod guide main body 111A as it moves radially outward. The step surface 142Aa is connected to the edge of the inner circumferential surface 141Aa on the side of the end face 111b in the axial direction. The step surface 142Aa forms a chamber 108.

[0055] The recess 143A is located at the middle of the step surface 142Aa in the radial direction of the rod guide main body 111A. The recess 143A is recessed from the step surface 142Aa toward the end surface 111b in the axial direction of the rod guide main body 111A. The recess 143A has an annular shape coaxial with the inner circumferential surface 141Aa. The bottom surface 143Aa of the recess 143A has an arc-shaped cross section in a plane including the central axis of the rod guide main body 111A. The width of the recess 143A decreases as the depth increases. Note that the cross section of the recess 143A in a plane including the central axis of the rod guide main body 111A may also have an angular shape. In the radial direction of the rod guide main body 111A, the bottom surface 143Aa of the recess 143A is entirely located inside the inner surface portion 123a of the step portion 123. In the axial direction of the rod guide main body 111A, the entire bottom surface 143Aa of the recess 143A is located closer to the end surface 111a than the inner side surface portion 123a of the step portion 123. The bottom surface 143Aa forms a chamber .

[0056] In the rod guide main body 111A, a communicating passage 151A having a shape partially different from that of the communicating passage 151 is formed instead of the communicating passage 151. The communicating passage 151A connects the recess 143A and the step portion 123. One end of the communicating passage 151A opens to a bottom surface 143Aa of the recess 143A, including the deepest position. The other end of the communicating passage 151A opens to a portion of the inner surface portion 123a of the step portion 123 that is radially outward from the inner cylinder 15. Therefore, the communicating passage 151A connects the bottom surface 143Aa of the recess 143A to the reservoir chamber 18.

[0057] Here, in the axial direction of the rod guide main body 111A, the inner surface portion 123a of the step portion 123 is located on the opposite side of the end face 111a from the bottom surface 143Aa of the recess 143A. As a result, the communicating passage 151A has a component that is directed inward in the cylinder inward / outward direction of the rod guide 26A, in other words, inward in the axial direction of the cylinder 17. The communicating passage 151A is linear, and the more outward in the radial direction of the rod guide main body 111A, the more inward in the cylinder inward / outward direction of the rod guide main body 111A is located. The angle of the communicating passage 151A with respect to the central axis of the rod guide main body 111A is different from the angle of the step surface 142Aa with respect to the central axis of the rod guide main body 111A.

[0058] A plurality of such communication passages 151A are provided at equal intervals around the circumferential direction of the rod guide main body 111A. All of the communication passages 151A provided in the rod guide main body 111A communicate between the bottom surface 143Aa of the recess 143A and the reservoir chamber 18. The plurality of communication passages 151A are arranged so that one of them opens at the vertically lowest position of the bottom surface 143Aa of the hydraulic shock absorber 11A when attached to the vehicle. Furthermore, when the hydraulic shock absorber 11A is attached to the vehicle, at least one of the plurality of communication passages 151A located on the lower side in the vertical direction is inclined so that it is positioned vertically downward as it approaches the reservoir chamber 18. Note that only one communication passage 151A may be provided for the rod guide main body 111A. In this case, too, this communication passage 151A opens at the lowest vertical position on the bottom surface 143Aa of the hydraulic shock absorber 11A when attached to the vehicle, and is inclined so that it is positioned vertically lower as it approaches the reservoir chamber 18.

[0059] The main lip 102 of the seal member 41 faces the step surface 142Aa of the hole step portion 142A and the bottom surface 143Aa of the recess 143A in the axial direction of the rod guide main body 111A. In other words, the recess 143A faces the main lip 102 in the axial direction of the rod guide main body 111A.

[0060] In the hydraulic shock absorber 11A of the second embodiment as well, contaminants may be discharged into the chamber 108 between the seal member 41 and the rod guide 26A together with the oil liquid L adhering to the rod 50. The contaminants thus discharged into the chamber 108 together with the oil liquid L move by gravity along the step surface 142Aa of the hole step portion 142A together with the oil liquid L or within the oil liquid L, and reach the bottom surface 143Aa of the recess 143A.

[0061] In the hydraulic shock absorber 11A of the second embodiment, the rod guide 26A has a component that faces inward in the axial direction of the cylinder 17, and a communication passage 151A that communicates between the bottom surface 143Aa of the recess 143A and the reservoir chamber 18. Therefore, in the hydraulic shock absorber 11A, contaminants that have reached the bottom surface 143Aa of the recess 143A can be discharged from the bottom surface 143Aa through the communication passage 151A together with the oil L into the reservoir chamber 18 by gravity or the like. Therefore, the hydraulic shock absorber 11A can suppress damage to the seal member 41.

[0062] [Third embodiment] Next, the third embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 4. Note that parts common to the first embodiment will be designated by the same names and symbols. The hydraulic shock absorber 11B of the third embodiment has a rod guide 26B that is partially different from the rod guide 26 instead of the rod guide 26. The rod guide 26B has a rod guide main body 111B that is partially different from the rod guide main body 111 instead of the rod guide main body 111. The rod guide main body 111B has a through hole 131B that is partially different in shape from the through hole 131 formed in place of the through hole 131. The through hole 131B has a large diameter hole portion 132B that is partially different in shape from the large diameter hole portion 132 instead of the large diameter hole portion 132.

[0063] The large diameter hole portion 132B has a hole inner peripheral portion 141B, a hole step portion 142B, and a recess 143B. The hole inner peripheral portion 141B has an inner peripheral surface 141Ba that extends from the inner peripheral edge of the end face 111a toward the end face 111b in the axial direction of the rod guide main body 111B. The inner peripheral surface 141Ba is a tapered surface, and its diameter decreases toward the end face 111b in the axial direction of the rod guide main body 111B. The inner peripheral surface 141Ba forms a chamber 108.

[0064] The hole step portion 142B has a step surface 142Ba that extends radially outward from the edge of the small diameter hole portion 133 on the opposite side of the medium diameter hole portion 134 in the axial direction of the rod guide main body 111B. The step surface 142Ba is flat and extends perpendicular to the central axis of the rod guide main body 111B. The step surface 142Ba forms a chamber 108.

[0065] The recess 143B is located outside the step surface 142Ba and inside the inner circumferential surface 141Ba in the radial direction of the rod guide main body 111B. The recess 143B is recessed from the step surface 142Ba toward the end face 111b in the axial direction of the rod guide main body 111B. The recess 143B has an annular shape coaxial with the inner circumferential surface 141Ba. The recess 143B has an inward wall surface 143Bb, an outward wall surface 143Bc, and a bottom surface 143Ba. The inward wall surface 143Bb faces inward in the radial direction of the rod guide main body 111B, and forms the same tapered surface as the inner peripheral surface 141Ba, continuing to the inner peripheral surface 141Ba. Therefore, the inward wall surface 143Bb is a tapered surface, and the diameter decreases toward the end face 111b in the axial direction of the rod guide main body 111B. The outward wall surface 143Bc faces radially outward of the rod guide main body 111B and has a smaller diameter than the inward wall surface 143Bb. The outward wall surface 143Bc is a tapered surface that is inclined like the inward wall surface 143Bb. Therefore, the diameter of the outward wall surface 143Bc decreases toward the end face 111b in the axial direction of the rod guide main body 111B.

[0066] The bottom surface 143Ba connects the edge of the inward wall surface 143Bb on the end surface 111b side to the edge of the outward wall surface 143Bc on the end surface 111b side in the axial direction of the rod guide main body 111B. The bottom surface 143Ba is a tapered surface. The bottom surface 143Ba is inclined so as to approach the end surface 111b in the axial direction of the rod guide main body 111B as it moves radially outward. The cross section of the recess 143B on a plane including the central axis of the rod guide main body 111 is angular. In the radial direction of the rod guide main body 111B, the bottom surface 143Ba of the recess 143B is entirely located inside the inner surface portion 123a of the step portion 123. In the axial direction of the rod guide main body 111B, the bottom surface 143Ba of the recess 143B is entirely located closer to the end surface 111a than the inner surface portion 123a of the step portion 123. The bottom surface 143Ba, the inward wall surface 143Bb, and the outward wall surface 143Bc form the chamber 108.

[0067] In the rod guide main body 111B, a communicating passage 151B having a shape partially different from that of the communicating passage 151 is formed instead of the communicating passage 151. The communicating passage 151B connects the recess 143B and the step portion 123. One end of the communicating passage 151B opens to the end of the inward wall surface 143Bb of the recess 143B closest to the bottom surface 143Ba. One end of the communicating passage 151B opens to the bottom surface 143Ba of the recess 143B, including its deepest position. The other end of the communicating passage 151B opens to a portion of the inner surface portion 123a of the step portion 123 that is radially outward from the inner cylinder 15. Therefore, the communicating passage 151B communicates between the bottom surface 143Ba of the recess 143B and the reservoir chamber 18.

[0068] Here, in the axial direction of the rod guide main body 111B, the inner surface portion 123a of the step portion 123 is located on the opposite side of the end face 111a from the bottom surface 143Ba of the recess 143B. As a result, the communicating passage 151B has a component that is directed inward in the cylinder inward / outward direction of the rod guide 26B, in other words, inward in the axial direction of the cylinder 17. The communicating passage 151B is linear, and the more outward in the radial direction of the rod guide main body 111B, the more inward in the cylinder inward / outward direction of the rod guide main body 111B is located. The communicating passage 151B extends in the direction of an extension of the bottom surface 143Ba. In other words, the angle of the communicating passage 151B with respect to the central axis of the rod guide main body 111B is equal to the angle of the bottom surface 143Ba with respect to the central axis of the rod guide main body 111B. The angle of the communication passage 151B relative to the central axis of the rod guide main body 111B may be different from the angle of the bottom surface 143Ba relative to the central axis of the rod guide main body 111B.

[0069] A plurality of such communication passages 151B are provided at equal intervals around the circumferential direction of the rod guide main body 111B. All of the communication passages 151B provided in the rod guide main body 111B communicate between the bottom surface 143Ba of the recess 143B and the reservoir chamber 18. The plurality of communication passages 151B are arranged so that one of them opens at the vertically lowest position of the bottom surface 143Ba of the hydraulic shock absorber 11B when attached to the vehicle. Furthermore, when the hydraulic shock absorber 11B is attached to the vehicle, at least one of the plurality of communication passages 151B located vertically lower is inclined so that it is positioned vertically lower as it approaches the reservoir chamber 18. Note that only one communication passage 151B may be provided for the rod guide main body 111B. In this case, too, this communication passage 151B opens at the lowest vertical position on the bottom surface 143Ba of the hydraulic shock absorber 11B when attached to the vehicle, and is inclined so that it is positioned vertically lower as it approaches the reservoir chamber 18.

[0070] The main lip 102 of the seal member 41 faces the step surface 142Ba of the hole step portion 142B and the bottom surface 143Ba of the recessed portion 143B in the axial direction of the rod guide main body 111B. In other words, the recessed portion 143B faces the main lip 102 in the axial direction of the rod guide main body 111B.

[0071] In the hydraulic shock absorber 11B of the third embodiment, contaminants may also be discharged into the chamber 108 between the seal member 41 and the rod guide 26B together with the oil liquid L adhering to the rod 50. The contaminants thus discharged into the chamber 108 together with the oil liquid L move by gravity along the step surface 142Ba of the hole step portion 142B together with the oil liquid L or within the oil liquid L, and reach the bottom surface 143Ba of the recess 143B.

[0072] In the hydraulic shock absorber 11B of the third embodiment, the rod guide 26B has a component that faces inward in the axial direction of the cylinder 17, and a communication passage 151B is provided that communicates between the bottom surface 143Ba of the recess 143B and the reservoir chamber 18. Therefore, in the hydraulic shock absorber 11B, contaminants that have reached the bottom surface 143Ba of the recess 143B can be discharged from the bottom surface 143Ba via the communication passage 151B to the reservoir chamber 18 together with the oil L by gravity or the like. Therefore, the hydraulic shock absorber 11B can suppress damage to the seal member 41.

[0073] [Fourth embodiment] Next, the fourth embodiment will be described, focusing on the differences from the third embodiment, mainly with reference to Fig. 5. Note that parts common to the third embodiment will be designated by the same names and symbols. A hydraulic shock absorber 11C of the fourth embodiment has a seal member 41C that is partially different from the seal member 41 in place of the seal member 41. The seal member 41C has a seal main body 91C that is partially different from the seal main body 91 in place of the seal main body 91. The seal main body 91C has an elastic seal portion 95C that is partially different from the elastic seal portion 95 in place of the elastic seal portion 95.

[0074] The elastic seal portion 95C further has a check lip portion 171C extending from the inner seal portion 105 to the same side as the main lip 102 in the axial direction of the seal member 41C. The check lip portion 171C is a tapered cylinder with both the inner and outer diameters decreasing toward the extended tip. The outer periphery of the tip of the check lip portion 171C on the extended side is cut out. As a result, the radial thickness of the tip of the check lip portion 171C becomes thinner toward the tip.

[0075] The tip of the extending side of the check lip portion 171C is inserted into the recessed portion 143B. The length of the check lip portion 171C is such that it does not extend outside the recessed portion 143B. When the pressure in the chamber 108 and the pressure in the reservoir chamber 18 are the same, the tip of the extending side of the check lip portion 171C abuts against the bottom surface 143Ba over the entire periphery. Then, the check lip portion 171C blocks communication between the communication passage 151B and the chamber 108.

[0076] When the pressure in the chamber 108 becomes lower than the pressure in the reservoir chamber 18, the check lip portion 171C elastically deforms, and its tip moves toward the outward wall surface 143Bc. The tip then abuts against the outward wall surface 143Bc. At this time, the tip of the check lip portion 171C on the extending side abuts against the bottom surface 143Ba over the entire periphery, blocking communication between the communication passage 151B and the chamber 108.

[0077] When the pressure in the chamber 108 becomes higher than the pressure in the reservoir chamber 18, the check lip portion 171C elastically deforms, and its tip moves toward the inward wall surface 143Bb. Then, the check lip portion 171C abuts against the inner circumferential surface 141Ba, and its tapered tip elastically deforms toward the communicating passage 151B. Then, the tip moves away from the bottom surface 143Ba, connecting the chamber 108 and the communicating passage 151B. That is, the check lip portion 171C opens and closes the communication passage 151B depending on the relationship between the pressure in the chamber 108 and the pressure in the reservoir chamber 18. The check lip portion 171C functions as a check valve that allows the movement of the oil L from the chamber 108 to the communication passage 151B and restricts the movement of the oil L from the communication passage 151B to the chamber 108.

[0078] In the hydraulic shock absorber 11C of the fourth embodiment, contaminants may also be discharged into the chamber 108 between the seal member 41C and the rod guide 26B together with the oil liquid L adhering to the rod 50. The contaminants thus discharged into the chamber 108 together with the oil liquid L move by gravity along the step surface 142Ba of the hole step portion 142B together with the oil liquid L or within the oil liquid L, and reach the bottom surface 143Ba of the recess 143B.

[0079] In the hydraulic shock absorber 11C of the fourth embodiment, the rod guide 26B has a component directed inward in the axial direction of the cylinder 17, and a communication passage 151B is provided that connects the bottom surface 143Ba of the recess 143B to the reservoir chamber 18. When the pressure in the chamber 108 becomes higher than the pressure in the reservoir chamber 18, the check lip portion 171C of the seal member 41C connects the chamber 108 to the communication passage 151B. Therefore, in the hydraulic shock absorber 11C, contaminants that have reached the bottom surface 143Ba of the recess 143B can be discharged from the bottom surface 143Ba through the communication passage 151B to the reservoir chamber 18 together with the oil L by gravity or the like. Therefore, the hydraulic shock absorber 11C can suppress damage to the seal member 41C.

[0080] Furthermore, in the hydraulic shock absorber 11C of the fourth embodiment, the check lip portion 171C blocks communication between the communication passage 151B and the chamber 108 when the pressure in the chamber 108 is lower than the pressure in the reservoir chamber 18. Therefore, the hydraulic shock absorber 11C can suppress, by the check lip portion 171C, backflow of oil L containing contaminants in the vicinity of the communication passage 151B from the reservoir chamber 18 side to the chamber 108 side, which occurs when the pressure in the chamber 108 is lower than the pressure in the reservoir chamber 18. Therefore, the hydraulic shock absorber 11C can further suppress damage to the seal member 41C.

[0081] [Fifth embodiment] Next, the fifth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 6. Note that parts common to the first embodiment will be designated by the same names and symbols. The hydraulic shock absorber 11D of the fifth embodiment has a rod guide 26D that is partially different from the rod guide 26 instead of the rod guide 26. The rod guide 26D further has a plate portion 181D.

[0082] The plate portion 181D is provided at an opening on the reservoir chamber 18 side of the communication passage 151. The plate portion 181D covers the opening on the reservoir chamber 18 side, which is a part of the communication passage 151. The plate portion 181D has a support shaft 182D, a first extending portion 183D, and a second extending portion 184D. The support shaft 182D is provided at the opening of the communication passage 151 on the reservoir chamber 18 side, and is provided at the inner end of this opening in the radial direction of the rod guide 26D. The first extending portion 183D extends from the support shaft 182D outward in the radial direction of the support shaft 182D. The second extending portion 184D extends outward in the radial direction of the support shaft 182D from a different angular position of the support shaft 182D from the first extending portion 183D. The second extending portion 184D is perpendicular to the first extending portion 183D. In other words, the first extending portion 183D and the second extending portion 184D form an L-shaped cross section in a plane perpendicular to the support shaft 182D. The extension length of the second extending portion 184D from the support shaft 182D is longer than the extension length of the first extending portion 183D from the support shaft 182D. The second extending portion 184D can close the opening of the communicating passage 151 on the reservoir chamber 18 side. The first extending portion 183D is located on the inner side of the communication passage 151 relative to the second extending portion 184D in a state in which the second extending portion 184D closes the opening of the communication passage 151 on the reservoir chamber 18 side.

[0083] When the pressure in chamber 108 becomes lower than the pressure in reservoir chamber 18, the plate portion 181D rotates around support shaft 182D due to the differential pressure generated in first extension portion 183D, and the second extension portion 184D blocks the opening of communicating passage 151 on the reservoir chamber 18 side, thereby cutting off communication between reservoir chamber 18 and communicating passage 151. When the pressure in chamber 108 becomes higher than the pressure in reservoir chamber 18, the plate portion 181D rotates around support shaft 182D due to the differential pressure generated in first extension portion 183D, and second extension portion 184D opens the opening of communicating passage 151 on the reservoir chamber 18 side, connecting communicating passage 151 and reservoir chamber 18. That is, the plate portion 181D opens and closes the communication passage 151 in accordance with the relationship between the pressure in the chamber 108 and the pressure in the reservoir chamber 18.

[0084] In the hydraulic shock absorber 11D of the fifth embodiment, contaminants may also be discharged into the chamber 108 between the seal member 41 and the rod guide 26D together with the oil liquid L adhering to the rod 50. The contaminants thus discharged into the chamber 108 together with the oil liquid L reach the bottom surface 143a of the recess 143 together with the oil liquid L or within the oil liquid L due to gravity.

[0085] In the hydraulic shock absorber 11D of the fifth embodiment, a communication passage 151 is provided in the rod guide 26D, the communication passage 151 having a component directed inward in the axial direction of the cylinder 17 and connecting the bottom surface 143a of the recess 143 to the reservoir chamber 18. Therefore, in the hydraulic shock absorber 11D, contaminants that reach the bottom surface 143a of the recess 143 can be discharged from the bottom surface 143a to the communication passage 151 by gravity. A plate portion 181D that covers a part of the communication passage 151 connects the communication passage 151 to the reservoir chamber 18 when the pressure in the chamber 108 becomes higher than the pressure in the reservoir chamber 18. This allows the contaminants in the communication passage 151 to be discharged to the reservoir chamber 18 together with the hydraulic fluid L. Therefore, the hydraulic shock absorber 11D can suppress damage to the seal member 41.

[0086] Furthermore, in the hydraulic shock absorber 11D of the fifth embodiment, the plate portion 181D blocks communication between the reservoir chamber 18 and the communication passage 151 when the pressure in the chamber 108 is lower than the pressure in the reservoir chamber 18. Therefore, the hydraulic shock absorber 11D can suppress, by the plate portion 181D, backflow of contaminated oil L near the communication passage 151 from the reservoir chamber 18 side to the chamber 108 side, which occurs when the pressure in the chamber 108 is lower than the pressure in the reservoir chamber 18. Therefore, the hydraulic shock absorber 11D can further suppress damage to the seal member 41.

[0087] The plate portion 181D may be provided on the rod guide 26A of the hydraulic shock absorber 11A of the second embodiment so as to be able to open and close the communication passage 151A. Also, the plate portion 181D may be provided on the rod guide 26B of the hydraulic shock absorber 11B of the third embodiment so as to be able to open and close the communication passage 151B.

[0088] [Sixth embodiment] Next, the sixth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 7. Note that parts common to the first embodiment will be designated by the same names and symbols. The hydraulic shock absorber 11E of the sixth embodiment has a rod guide 26E that is partially different from the rod guide 26 instead of the rod guide 26. The rod guide 26E further has a plate portion 181E.

[0089] The plate portion 181E is provided at an opening of the communicating passage 151 on the reservoir chamber 18 side. The plate portion 181E covers the opening of the communicating passage 151 on the reservoir chamber 18 side, which is a part of the communicating passage 151. The plate portion 181E has a support shaft 182E and an extending portion 184E. The support shaft 182E is provided at the opening of the communication passage 151 on the reservoir chamber 18 side, and is provided at the inner end of this opening in the radial direction of the rod guide 26E. The extension portion 184E extends from the support shaft 182E outward in the radial direction of the support shaft 182E. The extending portion 184E can close the opening of the communication passage 151 on the reservoir chamber 18 side. The extending portion 184E abuts against the inner side surface portion 123a to close the opening of the communication passage 151 on the reservoir chamber 18 side.

[0090] When the pressure in chamber 108 is lower than the pressure in reservoir chamber 18, the differential pressure generated in extension portion 184E causes plate portion 181E to block the opening of communicating passage 151 on the reservoir chamber 18 side, thereby blocking communication between reservoir chamber 18 and communicating passage 151. When the pressure in chamber 108 becomes higher than the pressure in reservoir chamber 18, the differential pressure generated in extension portion 184E causes extension portion 184E to rotate around support shaft 182E, opening the opening of communicating passage 151 on the reservoir chamber 18 side and connecting communicating passage 151 to reservoir chamber 18. That is, the plate portion 181E opens and closes the communication passage 151 in accordance with the relationship between the pressure in the chamber 108 and the pressure in the reservoir chamber 18.

[0091] In the hydraulic shock absorber 11E of the sixth embodiment, contaminants may also be discharged into the chamber 108 between the seal member 41 and the rod guide 26E together with the oil liquid L adhering to the rod 50. The contaminants thus discharged into the chamber 108 together with the oil liquid L reach the bottom surface 143a of the recess 143 together with the oil liquid L or within the oil liquid L due to gravity.

[0092] In the hydraulic shock absorber 11E of the sixth embodiment, a communication passage 151 is provided in the rod guide 26E, the communication passage 151 having a component directed inward in the axial direction of the cylinder 17 and connecting the bottom surface 143a of the recess 143 to the reservoir chamber 18. Therefore, in the hydraulic shock absorber 11E, contaminants that reach the bottom surface 143a of the recess 143 can be discharged from the bottom surface 143a to the communication passage 151 by gravity. A plate portion 181E that covers a part of the communication passage 151 connects the communication passage 151 to the reservoir chamber 18 when the pressure in the chamber 108 becomes higher than the pressure in the reservoir chamber 18. This allows the contaminants in the communication passage 151 to be discharged to the reservoir chamber 18 together with the hydraulic fluid L. Therefore, the hydraulic shock absorber 11E can suppress damage to the seal member 41.

[0093] Furthermore, in the hydraulic shock absorber 11E of the sixth embodiment, the plate portion 181E blocks communication between the reservoir chamber 18 and the communication passage 151 when the pressure in the chamber 108 is lower than the pressure in the reservoir chamber 18. Therefore, the hydraulic shock absorber 11E can suppress, by the plate portion 181E, backflow of contaminated oil L near the communication passage 151 from the reservoir chamber 18 side to the chamber 108 side, which occurs when the pressure in the chamber 108 is lower than the pressure in the reservoir chamber 18. Therefore, the hydraulic shock absorber 11E can further suppress damage to the seal member 41.

[0094] The plate portion 181E may be provided on the rod guide 26A of the hydraulic shock absorber 11A of the second embodiment so as to be able to open and close the communication passage 151A. Also, the plate portion 181E may be provided on the rod guide 26B of the hydraulic shock absorber 11B of the third embodiment so as to be able to open and close the communication passage 151B.

[0095] [Seventh embodiment] Next, the seventh embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 8. Note that parts common to the first embodiment will be designated by the same names and symbols. The hydraulic shock absorber 11F of the seventh embodiment further includes a filter unit 19F having a filter material such as a foam. The filter unit 19F is provided between the body 21 of the outer cylinder 16 and the inner cylinder 15. In other words, the filter unit 19F is provided in the reservoir chamber 18. The filter unit 19F is provided closer to the bottom 22 than the axial center of the body 21 of the outer cylinder 16 and the inner cylinder 15. The filter unit 19F is annular and is in close contact with the body 21 of the outer cylinder 16 and the inner cylinder 15 around its entire circumference. The filter unit 19F is fixed to the cylinder 17 by being in close contact with the body 21 and the inner cylinder 15. The filter unit 19F filters the oil liquid L with the filter material to capture contaminants as the oil liquid L passes through the filter material in the axial direction.

[0096] In the hydraulic shock absorber 11F of the seventh embodiment, contaminants discharged together with the oil L from the chamber 108 through the communicating passage 151 into the reservoir chamber 18 fall by gravity toward the bottom 22 within the oil L in the reservoir chamber 18. The hydraulic shock absorber 11F includes a filter unit 19F having a filter medium in the reservoir chamber 18, so that the filter unit 19F can capture such contaminants. This prevents the contaminants from migrating within the reservoir chamber 18 toward the base valve 30 beyond the filter unit 19F. This prevents the contaminants from affecting the opening and closing of the disc valves 75 and 76 of the base valve 30 and the opening and closing of the disc valves 67 and 68 of the piston 45. Furthermore, damage caused by the contaminants to the piston 45 sliding within the inner cylinder 15 can be prevented.

[0097] The filter section 19F may be provided between the trunk section 21 and the inner cylinder 15 of the outer cylinder 16 of the hydraulic shock absorbers 11A to 11E of the second to sixth embodiments.

[0098] [Eighth embodiment] Next, the eighth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 9. Note that parts common to the first embodiment will be designated by the same names and symbols. The hydraulic shock absorber 11G of the eighth embodiment further includes a filter unit 19G having a filter material such as a foam. The filter unit 19G is sandwiched between the bottom 22 of the outer cylinder 16 and a pin member 78 and fixed thereto. In other words, the filter unit 19G is provided in the reservoir chamber 18. The filter unit 19G is disk-shaped. When the oil liquid L passes through the filter material of the filter unit 19G, the filter unit 19G filters the oil liquid L with the filter material to capture contaminants.

[0099] In the hydraulic shock absorber 11G of the eighth embodiment, contaminants discharged together with the oil L from the chamber 108 through the communicating passage 151 into the reservoir chamber 18 fall by gravity toward the bottom 22 within the oil L. In the hydraulic shock absorber 11G, a filter unit 19G having a filter medium is provided in the reservoir chamber 18, so that such contaminants can be captured by the filter unit 19G. This prevents the contaminants from migrating toward the base valve 30 within the reservoir chamber 18. This prevents the contaminants from affecting the opening and closing of the disc valves 75, 76 of the base valve 30 and the opening and closing of the disc valves 67, 68 of the piston 45. This also prevents damage caused by the contaminants to the piston 45 sliding within the inner cylinder 15.

[0100] The filter portion 19G may be provided on the bottom portion 22 of the outer cylinder 16 of the hydraulic shock absorbers 11A to 11E of the second to sixth embodiments. [Explanation of symbols]

[0101] 11, 11A to 11G...hydraulic shock absorber, 15...inner cylinder, 16...outer cylinder, 18...reservoir chamber, 19F, 19G...filter portion, 26, 26A, 26B, 26D, 26E...rod guide, 41, 41C...sealing member, 50...rod, 102...main lip (lip), 143, 143A, 143B...recess, 143a, 143Aa, 143Ba...bottom surface, 151, 151A, 151B...communicating passage, 181D, 181E...plate portion.

Claims

1. A cylindrical outer tube; a cylindrical inner cylinder inserted into the outer cylinder to form a reservoir chamber between the inner cylinder and the outer cylinder; a rod inserted into the inner cylinder; a seal member having a lip extending inward in the axial direction and sealing between the rod and the outer cylinder; a rod guide inserted into the inner cylinder axially inward of the seal member and into which the rod is inserted, The rod guide is a recess facing the lip; a communication passage having an axially inward component, the communication passage connecting the bottom surface of the recess and the reservoir chamber; a plate portion covering a part of the communication passage; and The plate portion rotates around a support shaft provided at the opening of the communication passage on the reservoir chamber side to open and close the opening. Hydraulic shock absorber.

2. The hydraulic shock absorber is Further provided is a filter unit having a filter material in the reservoir chamber. The hydraulic shock absorber according to claim 1.

Images