Shock absorber

Abstract

In the present invention, a shock absorber comprises: a stopper member that is provided to a piston rod; an elastic member that is provided between the stopper member and the rod guide, that is formed so that a working fluid can flow between the radially outward periphery and the cylinder, that moves together with the piston rod, and that is deformable; and a washer that is provided between the stopper member and the elastic member. In the shock absorber, a first passage through which the working fluid can flow is formed between the cylinder and a radially outward peripheral surface of the washer, a second passage through which the working fluid can flow is formed between the piston rod and a radially inward peripheral surface of the washer, and a third passage that communicates with the second passage is provided in the washer or the stopper member.

Description

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[0001] This application claims priority to Japanese Patent Application No. 2023-119001, filed on July 21, 2023, the contents of which are incorporated herein by reference.

[0002] Some shock absorbers have an elastic member that absorbs the impact when the shock absorber is fully extended (see, for example, Patent Documents 1 to 3).

[0003] Japanese Patent Application Publication No. 2014-92169 Japanese Patent Application Publication No. 48-4465 Japanese Patent Application Publication No. 2015-152094

[0004] A shock absorber is required to generate a stable damping force.

[0005] Therefore, an object of the present invention is to provide a shock absorber that can generate a stable damping force.

[0006] In order to achieve the above object, a shock absorber according to one aspect of the present invention has the following configuration: a cylinder in which a working fluid is sealed; a piston slidably fitted within the cylinder to divide the interior of the cylinder into two chambers; a rod guide that closes the cylinder; a piston rod that is inserted through the rod guide, with a first end connected to the piston and a second end extending to the outside of the cylinder; a stopper member that is provided on the piston rod; an elastic member that is provided between the stopper member and the rod guide, and is formed so that the working fluid can flow between its radial outer periphery and the cylinder, and that moves and deforms together with the piston rod; a washer that is provided between the stopper member and the elastic member; wherein a first passage through which the working fluid can flow is formed between the radial outer periphery of the washer and the cylinder; a second passage through which the working fluid can flow is formed between the radial inner periphery of the washer and the piston rod; and a third passage that communicates with the second passage is provided in the washer or the stopper member.

[0007] According to the shock absorber according to the above aspect of the present invention, it is possible to generate a stable damping force.

[0008] Fig. 1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view showing a main part of a shock absorber according to the first embodiment of the present invention. Fig. 3 is a cross-sectional view showing a main part of a shock absorber according to a second embodiment of the present invention. Fig. 4 is a cross-sectional view showing a main part of a shock absorber according to a third embodiment of the present invention. Fig. 5 is a cross-sectional view showing a main part of a shock absorber according to a fourth embodiment of the present invention. Fig. 6 is a cross-sectional view showing a main part of a shock absorber according to a fifth embodiment of the present invention.

[0009] [First Embodiment] The first embodiment will be described below with reference to Figures 1 and 2. Figure 1 shows a shock absorber 11 according to the first embodiment. The shock absorber 11 is used in a suspension system for a vehicle such as an automobile or a railway vehicle. Specifically, the shock absorber 11 is used in a suspension system for an automobile. The shock absorber 11 is a twin-tube shock absorber including a cylinder 17 having an inner tube 15 and an outer tube 16. The inner tube 15 is cylindrical. The outer tube 16 is cylindrical with a bottom and has a larger diameter than the inner tube 15. The outer tube 16 is disposed radially outward of the inner tube 15 and coaxially with the inner tube 15. A reservoir chamber 18 is defined between the outer tube 16 and the inner tube 15.

[0010] The outer cylinder 16 has a body member 20 and a bottom member 21. The body member 20 has a stepped cylindrical shape with an axially intermediate portion having a larger diameter than both axially opposite portions. The bottom member 21 is fitted and fixed to one axial end of the body member 20. The fitted portion of the bottom member 21 with the body member 20 and the body member 20 together form a cylindrical body portion 22 of the outer cylinder 16. The body portion 22 has a stepped cylindrical shape. A portion of the bottom member 21 radially inward from the fitted portion with the body member 20 forms a bottom portion 23 of the outer cylinder 16. The bottom portion 23 closes one axial end of the body portion 22. The side of the body portion 22 opposite the bottom portion 23 forms an opening 24. The opening 24 of the outer cylinder 16 is also provided at one axial end of the cylinder 17. The bottom portion 23 of the outer cylinder 16 is also provided at the other axial end of the cylinder 17. In other words, the cylinder 17 has an opening 24 at one axial end and a bottom 23 at the other axial end.

[0011] A mounting eye (not shown) is fixed to the side of the bottom 23 opposite the opening 24. The mounting eye is connected to the wheel side of the vehicle. A spring seat 25 is attached to the outer periphery of the body 22. The spring seat 25 receives the lower end of a spring (not shown) that supports the vehicle body. The inner cylinder 15 is a cylindrical, one-piece molded product made from a single piece of metal. The inner circumferential surface 15a of the inner cylinder 15 is cylindrical.

[0012] The shock absorber 11 includes a valve body 27 and a rod guide 28. The valve body 27 is annular and is provided at one axial end of the inner cylinder 15 and the outer cylinder 16. The rod guide 28 is annular and is provided at the other axial end of the inner cylinder 15 and the outer cylinder 16. The valve body 27 constitutes the base valve 30, and its outer periphery is stepped. The valve body 27 is placed on the bottom 23. At this time, the large-diameter portion of the outer periphery of the valve body 27 is positioned radially relative to the outer cylinder 16.

[0013] As shown in FIG. 2 , the rod guide 28 includes a rod guide main body 32 and a collar 33. The rod guide main body 32 is made of metal and has an annular shape. The rod guide main body 32 has a large-diameter portion 35 and a small-diameter portion 36 on its outer periphery. The outer diameter of the large-diameter portion 35 is larger than the outer diameter of the small-diameter portion 36. Thus, the rod guide main body 32 has a stepped outer periphery. The collar 33 is cylindrical. The collar 33 is formed by coating the inner periphery of a metal cylinder with a highly slidable material. The collar 33 is fitted and fixed to the inner periphery of the rod guide main body 32. The large-diameter portion 35 of the rod guide 28 fits into the inner periphery of the barrel portion 22 of the outer tube 16 on the opening 24 side. The rod guide 28 has an end surface 28 a at the end opposite the large-diameter portion 35 in the axial direction, which is flat and extends perpendicular to the central axis of the rod guide 28. The end surface 28 a is formed on the rod guide body 32 and the collar 33 .

[0014] As shown in FIG. 1 , one axial end of the inner cylinder 15 is fitted into the small-diameter portion of the outer periphery of the valve body 27 until it axially abuts against the large-diameter portion of the valve body 27. One axial end of the inner cylinder 15 engages with the bottom portion 23 of the outer cylinder 16 via the valve body 27. The other axial end of the inner cylinder 15 is fitted into the outer periphery of the small-diameter portion 36 of the rod guide main body 32 until it axially abuts against the large-diameter portion 35 of the rod guide main body 32. This other end of the inner cylinder 15 engages with the barrel portion 22 of the outer cylinder 16 via the rod guide 28. In this state, the inner cylinder 15 is positioned axially and radially relative to the outer cylinder 16. The valve body 27 and the bottom portion 23 communicate with each other via a passage groove 40 formed in the valve body 27. The space between the valve body 27 and the bottom 23 constitutes a reservoir chamber 18 , similar to the space between the inner cylinder 15 and the outer cylinder 16 .

[0015] The shock absorber 11 includes an annular rod seal 41. The rod seal 41 is provided on the side of the rod guide 28 opposite the bottom portion 23. Like the rod guide 28, the rod seal 41 is fitted to the inner periphery of the body portion 22. A locking portion 43 is formed on the end of the body portion 22 opposite the bottom portion 23. The locking portion 43 is formed by plastically deforming the body member 20 radially inward by a crimping process such as a curling process. The rod seal 41 is sandwiched between the locking portion 43 and the rod guide 28. At this time, the rod seal 41 is pressed against the inner periphery of the body portion 22 by the rod guide 28. As a result, the rod seal 41 closes the opening 24 of the outer cylinder 16. In other words, the rod guide 28 and the rod seal 41 together close the opening 24 at the end of the cylinder 17. The rod seal 41 is specifically an oil seal.

[0016] The shock absorber 11 includes a piston 45. The piston 45 is slidably disposed within the cylinder 17. The piston 45 is slidably fitted within the inner tube 15 of the cylinder 17. The piston 45 divides the inner tube 15 into two chambers: a first chamber 48 and a second chamber 49. The first chamber 48 is disposed between the piston 45 and the rod guide 28 within the inner tube 15. The second chamber 49 is disposed between the piston 45 and the valve body 27 within the inner tube 15. The second chamber 49 is separated from the reservoir chamber 18 by the valve body 27. Within the cylinder 17, oil L as a working fluid is sealed in the first chamber 48 and the second chamber 49. Within the cylinder 17, oil L and gas G as working fluids are sealed in the reservoir chamber 18.

[0017] The shock absorber 11 includes a piston rod 51. A first axial end of the piston rod 51 is disposed inside the cylinder 17. The first end of the piston rod 51 is connected to the piston 45. A second axial end of the piston rod 51, which is opposite the first axial end, extends to the outside of the cylinder 17 through the opening 24 of the outer cylinder 16. The piston rod 51 is made of metal and passes through the first chamber 48. The piston rod 51 does not pass through the second chamber 49. Therefore, the first chamber 48 is a rod-side chamber through which the piston rod 51 passes. The second chamber 49 is a bottom-side chamber on the bottom 23 side of the cylinder 17. The second end of the piston rod 51, which extends to the outside from the cylinder 17, is connected to the vehicle body.

[0018] The piston rod 51 has a main shaft portion 52 and a mounting shaft portion 53 on the first end side. The outer diameter of the mounting shaft portion 53 is smaller than the outer diameter of the main shaft portion 52. The outer peripheral surface 52a of the main shaft portion 52 is cylindrical. The mounting shaft portion 53 side of the piston rod 51 is inserted into the cylinder 17. A piston 45 is connected to the mounting shaft portion 53 of the piston rod 51 with a nut 54. The piston rod 51 extends from the cylinder 17 to the outside through a rod guide 28 and a rod seal 41 at the main shaft portion 52. The rod guide 28 and the rod seal 41 are provided on the side of the cylinder 17 from which the piston rod 51 extends. The rod guide 28 slidably supports the piston rod 51. The piston rod 51 is guided by the rod guide 28 at the outer peripheral surface 52a of the main shaft portion 52. The piston rod 51 moves axially together with the piston 45 relative to the cylinder 17. During the extension stroke of the shock absorber 11, the piston 45 moves toward the first chamber 48, while the piston rod 51 increases the amount of protrusion from the cylinder 17. During the compression stroke of the shock absorber 11, the piston 45 moves toward the second chamber 49, while the piston rod 51 decreases the amount of protrusion from the cylinder 17.

[0019] The rod seal 41 is provided on the side from which the piston rod 51 of the cylinder 17 extends, i.e., on the side of the opening 24 of the outer cylinder 16. The rod seal 41 seals the gap between the body 22 of the outer cylinder 16 and the main shaft portion 52 of the piston rod 51 via the rod guide 28, and prevents the oil L in the inner cylinder 15 and the gas G and oil L in the reservoir chamber 18 from leaking to the outside.

[0020] A passage 55 and a passage 56 are formed in the piston 45. Both the passage 55 and the passage 56 penetrate the piston 45 in the axial direction. The passages 55, 56 can communicate between the first chamber 48 and the second chamber 49. The shock absorber 11 includes a disc valve 57 and a disc valve 58. The disc valve 57 is provided on the side of the piston 45 opposite the bottom 23 in the axial direction. The disc valve 57 is annular and closes the passage 55 by abutting against the piston 45. The disc valve 57 opens the passage 55 by deforming its outer periphery away from the piston 45. The disc valve 58 is provided on the bottom 23 side of the piston 45 in the axial direction. The disc valve 58 is annular and closes the passage 56 by abutting against the piston 45. The disc valve 58 opens the passage 56 by deforming its outer periphery away from the piston 45. The disc valves 57 and 58 are attached to the mounting shaft portion 53 of the piston rod 51 together with the piston 45 .

[0021] When the piston rod 51 moves toward the compression side, increasing the amount of penetration into the inner cylinder 15 and the outer cylinder 16, and the piston 45 moves in a direction narrowing the second chamber 49, and 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 57 opens the passage 55, allowing the oil L in the second chamber 49 to flow through the passage 55 into the first chamber 48. At this time, the disc valve 57 generates a damping force. The disc valve 57 and the passage 55 constitute a compression-side damping force generating mechanism 59 that is provided in the piston 45 and generates a damping force.

[0022] When the piston rod 51 moves toward the extension side, increasing the amount of protrusion from the inner cylinder 15 and the outer cylinder 16, and the piston 45 moves in a direction narrowing the first chamber 48, and 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 58 opens the passage 56, allowing the oil L in the first chamber 48 to flow through the passage 56 to the second chamber 49. At this time, the disc valve 58 generates a damping force. The disc valve 58 and the passage 56 constitute an extension-side damping force generating mechanism 60 that is provided in the piston 45 and generates a damping force.

[0023] A fixed orifice (not shown) is formed in at least one of the piston 45 and the disc valve 57. This fixed orifice allows communication between the first chamber 48 and the second chamber 49 via the passage 55 even when the disc valve 57 is in a state where the passage 55 is fully closed by the disc valve 57. In addition, a fixed orifice (not shown) is also formed in at least one of the piston 45 and the disc valve 58. This fixed orifice allows communication between the first chamber 48 and the second chamber 49 via the passage 56 even when the disc valve 58 is in a state where the passage 56 is fully closed by the disc valve 58. These fixed orifices also constitute damping force generating mechanisms 59, 60.

[0024] The valve body 27 is formed with a fluid passage 63 and a fluid passage 64. Both the fluid passage 63 and the fluid passage 64 axially penetrate the valve body 27. Both the fluid passages 63 and 64 can communicate between the second chamber 49 and the reservoir chamber 18. The base valve 30 includes a disc valve 65 and a disc valve 66. The disc valve 65 is provided on the bottom 23 side of the valve body 27 in the axial direction. The disc valve 65 closes the fluid passage 63 by abutting against the valve body 27. The disc valve 66 is provided on the opposite side of the valve body 27 from the bottom 23 in the axial direction. The disc valve 66 closes the fluid passage 64 by abutting against the valve body 27. The base valve 30 includes a pin 68. The pin 68 attaches the disc valves 65 and 66 to the valve body 27. The valve body 27, the disc valves 65 and 66, the pin 68, and the like constitute the base valve 30.

[0025] When the piston rod 51 moves toward the compression side and the piston 45 moves in a direction narrowing the second chamber 49, causing the pressure in the second chamber 49 to exceed the pressure in the reservoir chamber 18 by a predetermined value or more, the disc valve 65 of the base valve 30 opens the fluid passage 63, allowing the hydraulic fluid L in the second chamber 49 to flow into the reservoir chamber 18. At this time, the disc valve 65 generates a damping force. When the piston rod 51 moves toward the extension side and the piston 45 moves toward the first chamber 48, causing the pressure in the second chamber 49 to fall below the pressure in the reservoir chamber 18, the disc valve 66 of the base valve 30 opens the fluid passage 64, allowing the hydraulic fluid L in the reservoir chamber 18 to flow into the second chamber 49. The disc valve 66 is a suction valve that allows the hydraulic fluid L to flow from the reservoir chamber 18 into the second chamber 49 without generating any substantial damping force.

[0026] The shock absorber 11 includes a cover 71. The cover 71 is attached to the opening 24 side of the body 22 of the outer cylinder 16. The cover 71 covers the opening 24 side of the body 22 and the rod seal 41.

[0027] The shock absorber 11 includes a locking ring 80, a stopper member 81, a washer 82, and an elastic member 83. The locking ring 80, the stopper member 81, the washer 82, and the elastic member 83 are all provided on the piston rod 51.

[0028] An engagement groove 85 is formed in the main shaft portion 52 of the piston rod 51. The engagement groove 85 is recessed radially inward from the outer circumferential surface 52a of the main shaft portion 52. The engagement groove 85 is annular and coaxial with the outer circumferential surface 52a of the main shaft portion 52. The engagement groove 85 is located within the inner cylinder 15 of the main shaft portion 52, and is formed in a predetermined position located between the piston 45 and the rod guide 28.

[0029] The locking ring 80 is made of metal and has a C-shape with a portion of the ring broken off. The locking ring 80 is fitted into the engagement groove 85. This restricts the axial movement of the locking ring 80 relative to the piston rod 51.

[0030] The stopper member 81 is made of metal and has an annular shape. As shown in FIG. 2 , the stopper member 81 has a stopper main body 91 and a cylindrical engaging portion 92. The stopper main body 91 is annular. The cylindrical engaging portion 92 is cylindrical. The outer diameter of the cylindrical engaging portion 92 is smaller than the outer diameter of the stopper main body 91. The outer diameter of the stopper member 81, i.e., the outer diameter of the stopper main body 91, is smaller than the inner diameter of the inner cylinder 15.

[0031] The main shaft portion 52 of the piston rod 51 is inserted into the inner peripheral surface 81c of the stopper member 81. At this time, the main shaft portion 52 of the piston rod 51 is fitted into the stopper main body portion 91 of the stopper member 81 at the outer peripheral surface 52a. At this time, the stopper main body portion 91 of the stopper member 81 is positioned closer to the rod guide 28 than the cylindrical engaging portion 92 in the axial direction. Here, the cylindrical engaging portion 92 is cylindrical before being attached to the piston rod 51. The stopper member 81 has the locking ring 80 disposed radially inside the cylindrical engaging portion 92. In this state, the cylindrical engaging portion 92 is crimped radially inward and plastically deformed. This causes the cylindrical engaging portion 92 to restrict radial expansion of the locking ring 80. At the same time, the axial movement of stopper main body 91 and cylindrical engaging portion 92, i.e., stopper member 81, relative to piston rod 51 is restricted by locking ring 80. Stopper member 81 is fixed to piston rod 51 by pressure contact of cylindrical engaging portion 92 against outer peripheral surface 52a of main shaft portion 52.

[0032] 2 , when the stopper member 81 is attached to the piston rod 51, it is formed so as to extend from the piston rod 51 in the radial direction of the piston rod 51. In this attached state, an end face 81a of the stopper member 81 on the rod guide 28 side in the axial direction is flat and extends perpendicular to the central axis of the piston rod 51. In addition, in this attached state, an outer peripheral end face 81b of the stopper member 81 is substantially cylindrical and centered on the central axis of the piston rod 51. The end face 81a and the outer peripheral end face 81b are formed on a stopper main body 91.

[0033] The stopper member 81 is disposed in the inner cylinder 15 together with the piston rod 51. As shown in FIG. 1 , the stopper member 81 is disposed between the piston 45 and the rod guide 28 in the axial direction of the piston rod 51. In other words, the stopper member 81 is fixed at a position on the piston rod 51 between the rod guide 28 and the piston 45. The stopper member 81 moves integrally with the piston rod 51 in the inner cylinder 15. As shown in FIG. 2 , the stopper member 81 has a radial gap between itself and the inner circumferential surface 15a of the inner cylinder 15 located radially outward of it. That is, the stopper member 81 has a radial gap between its outer circumferential end surface 81b and the inner circumferential surface 15a of the inner cylinder 15 located radially outward of it. This gap is annular and follows the inner circumferential surface 15a of the inner cylinder 15. A passage 121 through which the oil L can flow is formed between the outer peripheral end surface 81b of the stopper member 81 and the inner peripheral surface 15a of the inner tube 15. In other words, the stopper member 81 is formed so that the oil L as a working fluid can flow between the outer periphery in the radial direction and the inner tube 15 of the cylinder 17.

[0034] The washer 82 is made of synthetic resin and has an annular shape. Specifically, the washer 82 is made of nylon, but other materials may be used. The washer 82 has an outer peripheral surface 82a on the radially outer side, an inner peripheral surface 82b on the radially inner side, an end face 82c on one axial side, and an end side surface 82d on the other axial side. The outer peripheral surface 82a has an outer peripheral end surface 82aa, an outer peripheral tapered surface 82ab, and an outer peripheral tapered surface 82ac. The inner peripheral surface 82b has an inner peripheral end surface 82ba and a longitudinal groove 101. The end side surface 82d has an end surface 82da (abutment surface) and a lateral groove 102.

[0035] The outer peripheral end surface 82aa has a cylindrical surface shape.

[0036] The outer peripheral tapered surface 82ab is continuous with the outer peripheral end surface 82aa and the end surface 82c. The outer peripheral tapered surface 82ab has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82aa in the axial direction of the outer peripheral surface 82a.

[0037] The outer peripheral tapered surface 82ac is provided on the end side surface 82d side of the outer peripheral end surface 82aa. The outer peripheral tapered surface 82ac is continuous with the outer peripheral end surface 82aa. The outer peripheral tapered surface 82ac has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82aa in the axial direction of the outer peripheral surface 82a.

[0038] The inner peripheral end surface 82ba has a cylindrical surface shape that is discontinuous in the circumferential direction of the washer 82. The inner peripheral end surface 82ba is arranged coaxially with the outer peripheral surface 82a. The washer 82 is formed with a vertical groove 101 that is recessed radially outward from the broken portion of the inner peripheral end surface 82ba. The vertical groove 101 extends linearly in the axial direction of the washer 82 and penetrates the washer 82 in the axial direction of the washer 82. For example, the vertical groove 101 has an arc-shaped cross section in a plane extending perpendicular to the extension direction. In other words, the width of the vertical groove 101 in the circumferential direction of the washer 82 becomes narrower the further radially outward the washer 82 is. A plurality of vertical grooves 101 of the same shape are formed in the washer 82 at equal intervals in the circumferential direction of the washer 82.

[0039] The end surface 82c is a flat surface extending perpendicular to the central axis of the outer peripheral surface 82a and the inner peripheral surface 82b. The end surface 82c is continuous with the inner peripheral end surface 82ba.

[0040] The end face 82da is a plane that extends intermittently in the circumferential direction of the washer 82. The end face 82da is a plane that extends perpendicular to the central axis of the outer peripheral surface 82a and the inner peripheral surface 82b. The end face 82da is parallel to the end face 82c and faces the opposite side from the end face 82c. The end face 82da is continuous with the outer peripheral tapered surface 82ac and the inner peripheral end face 82ba.

[0041] The washer 82 has a lateral groove 102 formed in the end face 82da, recessed inward in the axial direction of the washer 82 from the broken portion of the end face 82da. In other words, the washer 82 has the lateral groove 102 formed in the end face 82da. The lateral groove 102 extends linearly in the radial direction of the washer 82 and penetrates the washer 82 in the radial direction. The lateral groove 102 has, for example, an arc-shaped cross section in a plane extending perpendicular to the extension direction. In other words, the lateral groove 102 has a width in the circumferential direction of the washer 82 that narrows toward the inside in the axial direction of the washer 82. A plurality of lateral grooves 102 of the same shape are formed in the washer 82 at equal intervals in the circumferential direction of the washer 82. In other words, the washer 82 has the lateral grooves 102 formed radially from the central axis of the washer 82.

[0042] The washer 82 is formed with the same number of longitudinal grooves 101 and lateral grooves 102. The longitudinal grooves 101 and the lateral grooves 102 are aligned in phase in the circumferential direction of the washer 82. In other words, the longitudinal grooves 101 and the lateral grooves 102 communicate with each other in phase with one another in a one-to-one correspondence. One end of each longitudinal groove 101 in the axial direction of the washer 82 opens to the end face 82c, and the other end opens to the corresponding lateral groove 102. One end of each lateral groove 102 in the radial direction of the washer 82 opens to the outer peripheral tapered surface 82ac and the outer peripheral end face 82aa of the outer peripheral surface 82a, and the other end opens to the corresponding longitudinal groove 101.

[0043] The inner diameter of the washer 82 is slightly larger than the outer diameter of the main shaft portion 52 of the piston rod 51. That is, the diameter of the inner peripheral end surface 82ba of the washer 82 is slightly larger than the diameter of the outer peripheral surface 52a of the main shaft portion 52.

[0044] The washer 82 is disposed radially outward of the main shaft portion 52 of the piston rod 51 with a gap therebetween, and an end face 82da of the washer 82 abuts against an end face 81a of the stopper member 81. The washer 82 is free relative to the piston rod 51. The washer 82 may also be fixed by fitting it to the main shaft portion 52 of the piston rod 51 with an interference fit.

[0045] 2 , in an attached state in which it is attached to the main shaft portion 52, the washer 82 is provided at a position on the piston rod 51 between the stopper member 81 and the rod guide 28. In other words, the washer 82 in the attached state is located on the rod guide 28 side of the stopper member 81 in an attached state in which it is attached to the main shaft portion 52. In further other words, in an attached state, the stopper member 81 is located entirely on the opposite side of the rod guide 28 in the axial direction of the piston rod 51 than the washer 82 in an attached state in which it is attached to the main shaft portion 52. The washer 82 moves together with the piston rod 51 by abutting against the stopper member 81.

[0046] The outer diameter of the washer 82 is smaller than the inner diameter of the inner cylinder 15. That is, the diameter of the outer peripheral end surface 82aa of the washer 82 is smaller than the diameter of the inner peripheral surface 15a of the inner cylinder 15. The outer diameter of the washer 82 is larger than the outer diameter of the stopper member 81. When attached to the main shaft portion 52 as shown in FIG. 2 , the washer 82 has a radial gap between its outer peripheral surface 82a and the inner peripheral surface 15a of the inner cylinder 15, which is located radially outward of the washer 82. This gap is annular and follows the inner peripheral surface 15a of the inner cylinder 15. A passage 122 (first passage) through which the oil L can flow is formed between the outer peripheral surface 82a of the washer 82 and the inner peripheral surface 15a of the inner cylinder 15. In other words, the washer 82 is formed to allow the oil L, as a working fluid, to flow between the radial outer periphery and the inner cylinder 15 of the cylinder 17.

[0047] A passage 123 (second passage) through which oil L can flow is formed between the vertical groove 101 provided on the inner peripheral surface 82b of the washer 82 and the outer peripheral surface 52a of the main shaft portion 52 of the piston rod 51. A passage 124 (third passage) through which oil L can flow is formed between the horizontal groove 102 provided on the end side surface 82d of the washer 82 and the end surface 81a of the stopper member 81.

[0048] The elastic member 83 is made of an elastic material that is elastically deformable. The elastic member 83 is softer than the washer 82, in other words, made of an elastic material with lower spring characteristics than the washer 82. Specifically, the elastic member 83 is made of a rubber material, but other materials may be used. The elastic member 83 is annular. The elastic member 83 has an outer peripheral surface 83a on the radially outer side, an inner peripheral surface 83b on the radially inner side, an end face 83c on one axial side, and an end face 83d on the other axial side. The outer peripheral surface 83a has an outer peripheral end surface 83aa, an outer peripheral tapered surface 83ab, and an outer peripheral tapered surface 83ac. The inner peripheral surface 83b has an inner peripheral end surface 83ba, an inner peripheral tapered surface 83bb, and an inner peripheral tapered surface 83bc. The outer peripheral surface 83a and the inner peripheral surface 83b are arranged coaxially.

[0049] The outer peripheral end surface 83aa has a cylindrical surface shape.

[0050] The outer peripheral tapered surface 83ab is continuous with the outer peripheral end surface 83aa and the end surface 83c. The outer peripheral tapered surface 83ab has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 83aa in the axial direction of the outer peripheral surface 83a.

[0051] The outer peripheral tapered surface 83ac is continuous with the outer peripheral end surface 83aa and the end surface 83d. The outer peripheral tapered surface 83ac has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 83aa in the axial direction of the outer peripheral surface 83a.

[0052] The end surface 83c and the end surface 83d are both flat surfaces extending perpendicular to the central axes of the outer peripheral surface 83a and the inner peripheral surface 83b. The end surface 83c and the end surface 83d face in opposite directions.

[0053] The inner peripheral end surface 84aa is cylindrical.

[0054] The inner peripheral tapered surface 83bb is continuous with the inner peripheral end surface 83ba and the end surface 83c. The inner peripheral tapered surface 83bb has a tapered surface shape that increases in diameter as it moves away from the inner peripheral end surface 83ba in the axial direction of the inner peripheral surface 83b.

[0055] The inner peripheral tapered surface 83bc is continuous with the inner peripheral end surface 83ba and the end surface 83d. The inner peripheral tapered surface 83bc has a tapered surface shape that increases in diameter as it moves away from the inner peripheral end surface 83ba in the axial direction of the inner peripheral surface 83b.

[0056] The diameter of the inner peripheral end surface 83ba of the elastic member 83 is slightly larger than the diameter of the outer peripheral surface 52a of the main shaft portion 52. The outer diameter of the elastic member 83 is slightly smaller than the outer diameter of the washer .

[0057] The elastic member 83 is disposed radially outward of the main shaft portion 52 of the piston rod 51 with a gap therebetween, and an end face 83d of the elastic member 83 abuts against an end face 82c of the washer 82. Thus, the elastic member 83 is free to move with respect to the piston rod 51. The washer 82 is provided between the stopper member 81 and the elastic member 83. The elastic member 83 is provided at a position on the piston rod 51 between the stopper member 81 and the rod guide 28. The elastic member 83 is provided at a position on the piston rod 51 between the washer 82 and the rod guide 28. The elastic member 83 abuts against the washer 82, which in turn abuts against the stopper member 81, and thereby moves together with the piston rod 51.

[0058] The outer diameter of the elastic member 83 is smaller than the diameter of the inner circumferential surface 15a of the inner cylinder 15. When attached to the main shaft portion 52 as shown in FIG. 2 , the elastic member 83 has a radial gap between its outer circumferential surface 83a and the inner circumferential surface 15a of the inner cylinder 15 located radially outward. This gap is annular and follows the inner circumferential surface 15a of the inner cylinder 15. A passage 125 through which oil L can flow is formed between the outer circumferential surface 83a of the elastic member 83 and the inner circumferential surface 15a of the inner cylinder 15. In other words, the elastic member 83 is formed so that oil L as a working fluid can flow between the radial outer periphery and the inner cylinder 15 of the cylinder 17. A passage 126 through which oil L can flow is formed between the inner circumferential surface 83b of the elastic member 83 and the outer circumferential surface 52a of the main shaft portion 52 of the piston rod 51.

[0059] The diameter of the outer peripheral end surface 83aa of the elastic member 83 is slightly smaller than the diameter of the outer peripheral end surface 82aa of the washer 82. When the elastic member 83 is attached to the main shaft portion 52, the inner peripheral tapered surface 83bc of the elastic member 83 is located radially inward of the outer end of the vertical groove 101 of the washer 82 in the radial direction of the elastic member 83 and the washer 82.

[0060] In an attached state in which washer 82 is attached to main shaft portion 52, the entire washer 82 is disposed on the opposite side of rod guide 28 in the axial direction of piston rod 51 from elastic member 83 in an attached state in which washer 82 is attached to main shaft portion 52. Elastic member 83 in an attached state is provided between washer 82 in an attached state and rod guide 28.

[0061] Here, the flow path area of ​​a passage 123 between the vertical groove 101 of the washer 82 and the main shaft portion 52 and a passage 124 between the lateral groove 102 of the washer 82 and the stopper member 81 are formed to be larger than the flow path area of ​​a passage 125 between the elastic member 83 and the inner tube 15 of the cylinder 17. In addition, the flow path area of ​​the passage 123 between the vertical groove 101 of the washer 82 and the main shaft portion 52 and the passage 124 between the lateral groove 102 of the washer 82 and the stopper member 81 are formed to be larger than the flow path area through the damping force generating mechanisms 59, 60 provided in the piston 45 shown in FIG. 1 , specifically, the flow path area of ​​the damping force generating mechanisms 59, 60 when the valves are fully opened.

[0062] The locking ring 80, stopper member 81, washer 82, and elastic member 83 described above constitute an impact absorbing mechanism 111. The impact absorbing mechanism 111 stops the piston rod 51 when it moves to a predetermined position toward the fully extended side relative to the cylinder 17, and absorbs the impact that occurs at that time. The stopper member 81 is a so-called rebound stopper that restricts the piston rod 51 from moving further toward the extended side than the fully extended position. The elastic member 83 is a so-called rubber rebound cushion that absorbs the impact when the stopper member 81 restricts the piston rod 51 from moving further toward the extended side than the fully extended position. The washer 82 is a passage-forming member that forms passages 123 and 124 between the piston rod 51 and the stopper member 81 and the elastic member 83.

[0063] An axial tensile load is applied to the shock absorber 11, and the piston rod 51 moves axially relative to the cylinder 17 in the extension direction, which increases the overall length of the shock absorber 11. Then, the impact absorbing mechanism 111 also moves together with the piston rod 51 and approaches the rod guide 28. At that time, the oil L present between the rod guide 28 and the elastic member 83 of the first chamber 48 flows between the stopper member 81 of the first chamber 48 and the piston 45 through a passage 125 between the outer peripheral surface 83 a of the elastic member 83 and the inner peripheral surface 15 a of the inner cylinder 15, a passage 122 between the outer peripheral surface 82 a of the washer 82 and the inner peripheral surface 15 a of the inner cylinder 15, and a passage 121 between the outer peripheral end surface 81 b of the stopper member 81 and the inner peripheral surface 15 a of the inner cylinder 15. At that time, the oil liquid L between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through a passage 126 between the inner surface 83b of the elastic member 83 and the outer surface 52a of the main shaft portion 52 of the piston rod 51, a passage 123 between the vertical groove 101 provided on the inner surface 82b of the washer 82 and the outer surface 52a of the main shaft portion 52 of the piston rod 51, and a passage 124 between the horizontal groove 102 provided on the end side 82d of the washer 82 and the end face 81a of the stopper member 81, and through a passage 121 between the outer end face 81b of the stopper member 81 and the inner surface 15a of the inner tube 15, and then flows between the stopper member 81 of the first chamber 48 and the piston 45.

[0064] In other words, a passage 122 through which oil L as a working fluid can flow is formed between the radial outer peripheral surface 82a of the washer 82 and the inner tube 15 of the cylinder 17. Furthermore, a passage 123 through which oil L can flow is formed between the radial inner peripheral surface 82b of the washer 82 and the piston rod 51. Furthermore, a passage 124 communicating with the passage 123 is provided in the washer 82. The passage 124 is provided between the washer 82 and the stopper member 81. The passage 124 is formed in the end face 82da of the end faces 82da and 81a, which are the abutting surfaces between the washer 82 and the stopper member 81. The passage 124 formed by the lateral groove 102 is formed in the washer 82 and is formed in the same phase as the passage 123 formed by the vertical groove 101 also formed in the washer 82.

[0065] During the extension stroke, as described above, the shock absorbing mechanism 111 moves together with the piston rod 51 in a direction approaching the rod guide 28. At that time, the oil L present between the rod guide 28 and the elastic member 83 of the first chamber 48 flows through the passage 125 between the elastic member 83 and the inner cylinder 15, the passage 122 between the washer 82 and the inner cylinder 15, and the passage 121 between the stopper member 81 and the inner cylinder 15, to a position closer to the piston 45 than the stopper member 81 of the first chamber 48. At the same time, the oil L present between the rod guide 28 and the elastic member 83 of the first chamber 48 flows through the passage 126 between the elastic member 83 and the piston rod 51, the passages 123 and 124 between the piston rod 51, the stopper member 81, and the washer 82, and through the passage 121 between the stopper member 81 and the inner cylinder 15, to a position closer to the piston 45 than the stopper member 81 of the first chamber 48.

[0066] During the extension stroke, when the piston rod 51 reaches its maximum extension position relative to the cylinder 17, the elastic member 83 of the impact absorbing mechanism 111 comes into contact with the end face 28a of the rod guide 28, mainly at the end face 83c. When the piston rod 51 moves further in the extension direction relative to the cylinder 17 at this maximum extension, the elastic member 83 elastically deforms to absorb the impact, and the stopper member 81, together with the washer 82, restricts the piston rod 51 from moving further in the extension direction.

[0067] Incidentally, the above-mentioned Patent Documents 1 to 3 disclose shock absorbers having elastic members that absorb impacts at the time of maximum extension. In such shock absorbers, there is a possibility that the elastic members may deform in situations other than when absorbing impacts at the time of maximum extension, causing the damping force to become unstable. This type of instability in the damping force is particularly likely to occur when an elastic member made of a soft material is used to suppress the generation of abnormal noise when absorbing impacts at the time of maximum extension. Shock absorbers are required to generate a stable damping force.

[0068] The shock absorber 11 of the first embodiment includes a stopper member 81 provided on the piston rod 51, an elastic member 83 provided between the stopper member 81 and the rod guide 28, the elastic member 83 being formed so that oil liquid L, which is a working fluid, can flow between the radial outer periphery of the stopper member 81 and the inner tube 15 of the cylinder 17, and moving and deforming together with the piston rod 51, and a washer 82 provided between the stopper member 81 and the elastic member 83. The shock absorber 11 has a passage 122 formed between the radial outer periphery 82a of the washer 82 and the inner tube 15, through which the oil liquid L can flow. The shock absorber 11 also has a passage 123 formed between the radial inner periphery 82b of the washer 82 and the piston rod 51, through which the oil liquid L can flow. The shock absorber 11 also has a passage 124 provided in the washer 82, the passage 124 communicating with the passage 123. Therefore, the shock absorber 11 is capable of generating a stable damping force.

[0069] That is, in the shock absorber 11, when the moving speed of the piston rod 51 is faster than a predetermined value during the extension stroke, the flow rate of the oil liquid L between the rod guide 28 and the elastic member 83 in the first chamber 48, through the passage 125 between the elastic member 83 and the inner cylinder 15, the passage 122 between the washer 82 and the inner cylinder 15, and the passage 121 between the stopper member 81 and the inner cylinder 15, between the elastic member 83 in the first chamber 48 and the piston 45, is greater than when the moving speed of the piston rod 51 is equal to or lower than the predetermined value. As a result, when the moving speed of the piston rod 51 is faster than the predetermined value, the fluid force of the oil liquid L causes the elastic member 83 to deform radially outward so as to be sucked into the passage 122, more than when the moving speed of the piston rod 51 is equal to or lower than the predetermined value. This may narrow the passage 125 between the outer circumferential surface 83a and the inner circumferential surface 15a of the inner cylinder 15. Therefore, if passages 123 and 124 were not present, when the movement speed of the piston rod 51 is faster than a predetermined value, the flow resistance to the oil liquid L passing through passage 125 would be higher than when the movement speed of the piston rod 51 is below the predetermined value, which could result in a higher damping force.

[0070] In contrast, the shock absorber 11 of the first embodiment has passages 123 and 124 between the piston rod 51 and stopper member 81, and the washer 82. Therefore, even if the moving speed of the piston rod 51 becomes higher than a predetermined value and the elastic member 83 deforms radially outward so as to be sucked into the passage 122, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 passes through the passage 126 between the elastic member 83 deformed radially outward and the piston rod 51, the passage 123 between the piston rod 51 and the washer 82, the passage 124 between the stopper member 81 and the washer 82, and the passage 121 between the stopper member 81 and the inner cylinder 15, and then flows smoothly between the stopper member 81 of the first chamber 48 and the piston 45. This allows the shock absorber 11 to suppress the radially outward deformation of the elastic member 83 and suppress an unnecessary increase in damping force that occurs except at the time of maximum extension. Therefore, the shock absorber 11 can generate a stable damping force.

[0071] Even if the shock absorber 11 uses the elastic member 83 made of a soft material to suppress the generation of abnormal noise when absorbing the impact at full extension, the shock absorber 11 can suppress unnecessary damping force generated at times other than full extension by the shock absorber mechanism 111. Even if the shock absorber 11 uses the elastic member 83 made of a particularly soft material, it can avoid a state (a so-called hydraulic lock state) in which the elastic member 83 obstructs the flow of oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 to between the elastic member 83 of the first chamber 48 and the piston 45. Therefore, the shock absorber 11 can increase the degree of freedom in selecting the elastic member 83.

[0072] Furthermore, the shock absorber 11 is provided with a washer 82 in addition to the elastic member 83, and this washer 82 is provided with passages 123, 124. For this reason as well, the shock absorber 11 can suppress the influence on the degree of freedom in selecting the elastic member 83. For example, even if the same elastic material is selected so that there is no change in impact absorbing performance, it is possible to suppress the increase in damping force that occurred before the washer 82 was provided.

[0073] Furthermore, in the shock absorber 11, of the passages 123 and 124, the passage 124 is formed on the end face 82da of the washer 82, which is the contact surface between the washer 82 and the stopper member 81. Therefore, in the shock absorber 11, it is possible to eliminate the effect of the formation of the passage 124 on the durability of the elastic member 83, which is arranged on the opposite side of the washer 82 from the stopper member 81.

[0074] Furthermore, in the shock absorber 11, the passage 124 of the passages 123 and 124 is formed on the end surface 82da of the washer 82, which is the abutment surface between the washer 82 and the stopper member 81. Therefore, in the shock absorber 11, the passage 124 can be easily formed.

[0075] Furthermore, in the shock absorber 11, the passage 124 is formed in the washer 82 in the same phase as the passage 123. Therefore, the shock absorber 11 does not require the work of aligning the phases of the passage 123 and the passage 124 during assembly, making assembly easier.

[0076] Furthermore, the shock absorber 11 is formed so that the flow path area of ​​the passages 123 and 124 is larger than the flow path area of ​​the passage 125 between the elastic member 83 and the inner tube 15 of the cylinder 17. Therefore, the shock absorber 11 can further suppress the influence of the elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, the shock absorber 11 can generate a more stable damping force.

[0077] Furthermore, the shock absorber 11 is formed so that the flow path area of ​​the passages 123 and 124 is larger than the flow path area of ​​the damping force generating mechanisms 59 and 60 provided in the piston 45. Therefore, the shock absorber 11 can further suppress the influence on the damping force by the elastic member 83 that occurs at times other than the maximum extension. Therefore, the shock absorber 11 can generate a more stable damping force.

[0078] Second Embodiment Next, a second embodiment will be described, focusing on 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.

[0079] The shock absorber 11A of the second embodiment has an impact absorbing mechanism 111A that is partially different from the impact absorbing mechanism 111 instead of the impact absorbing mechanism 111. The impact absorbing mechanism 111A has a washer 82A that is partially different from the washer 82 instead of the washer 82.

[0080] The washer 82A is made of the same synthetic resin as the washer 82. The washer 82A has an outer peripheral surface 82Aa on the radially outer side, an inner peripheral surface 82Ab on the radially inner side, an end face 82c on one axial side similar to that of the washer 82, and an end face 82Ad on the other axial side. The outer peripheral surface 82Aa has an outer peripheral end face 82Aaa, and outer peripheral tapered surfaces 82ab and 82Aac similar to those of the washer 82. The inner peripheral surface 82Ab has an inner peripheral end face 82ba and a longitudinal groove 101A similar to those of the washer 82.

[0081] The outer peripheral end surface 82Aaa has a cylindrical surface shape.

[0082] The outer peripheral tapered surface 82ab is continuous with the outer peripheral end surface 82Aaa and the end surface 82c. The outer peripheral tapered surface 82ab has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82Aaa in the axial direction of the outer peripheral surface 82Aa.

[0083] The outer peripheral tapered surface 82Aac is continuous with the outer peripheral end surface 82Aaa and the end surface 82Ad. The outer peripheral tapered surface 82Aac has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82Aaa in the axial direction of the outer peripheral surface 82Aa.

[0084] The inner peripheral end surface 82ba has a cylindrical surface shape that is discontinuous in the circumferential direction of the washer 82A. The inner peripheral end surface 82ba is arranged coaxially with the outer peripheral surface 82Aa. The washer 82A has a vertical groove 101A that is recessed radially outward from the broken portion of the inner peripheral end surface 82ba. The vertical groove 101A extends linearly in the axial direction of the washer 82A and penetrates the washer 82A in the axial direction of the washer 82A. For example, the vertical groove 101A has an arc-shaped cross section in a plane extending perpendicular to its extension direction. In other words, the width of the vertical groove 101A in the circumferential direction of the washer 82A decreases toward the radially outer side of the washer 82A. A plurality of vertical grooves 101A of the same shape are formed in the washer 82A at equal intervals in the circumferential direction of the washer 82A.

[0085] The end surface 82c is a flat surface extending perpendicular to the central axis of the outer peripheral surface 82Aa and the inner peripheral surface 82Ab. The end surface 82c is continuous with the inner peripheral end surface 82ba.

[0086] The end surface 82Ad is a flat surface extending perpendicular to the central axis of the outer peripheral surface 82Aa and the inner peripheral surface 82Ab. The end surface 82Ad is parallel to the end surface 82c and faces away from the end surface 82c. The end surface 82Ad is continuous with the outer peripheral tapered surface 82Aac and the inner peripheral end surface 82ba.

[0087] A horizontal hole 102A is formed in the washer 82A along the radial direction of the washer 82A between the end face 82c and the end face 82Ad on both sides in the axial direction of the washer 82A. In other words, the horizontal hole 102A is formed between both axial ends of the washer 82A. The horizontal hole 102A is provided between the outer peripheral tapered surface 82ab and the outer peripheral tapered surface 82Aac in the axial direction of the washer 82A. The horizontal hole 102A extends linearly in the radial direction of the washer 82A and penetrates the washer 82A in the radial direction. The horizontal hole 102A has a circular cross section in a plane extending perpendicular to the extension direction. A plurality of horizontal holes 102A of the same shape are formed in the washer 82A at equal intervals around the circumference of the washer 82A. In other words, the washer 82A has horizontal holes 102A formed radially around the central axis of the washer 82A.

[0088] The washer 82A is formed with the same number of vertical grooves 101A and horizontal holes 102A. The vertical grooves 101A and the horizontal holes 102A are aligned in phase in the circumferential direction of the washer 82A. In other words, the vertical grooves 101A and the horizontal holes 102A are aligned in phase and communicate with each other so that one-to-one corresponding ones are aligned in phase. One end of the vertical groove 101A in the axial direction of the washer 82A opens to the end face 82c, and the other end opens to the end face 82Ad. One end of the horizontal hole 102A in the radial direction of the washer 82A opens to the outer peripheral end face 82Aaa, and the other end opens to the corresponding vertical groove 101A.

[0089] The main shaft portion 52 of the piston rod 51 is inserted into the radially inner side of the washer 82A, and the end face 82Ad abuts against the end face 81a of a stopper member 81 similar to that provided in the impact absorbing mechanism 111.

[0090] The outer diameter of the washer 82A is smaller than the inner diameter of the inner cylinder 15. That is, the diameter of the outer peripheral end surface 82Aaa of the washer 82A is smaller than the diameter of the inner peripheral surface 15a of the inner cylinder 15. The outer diameter of the washer 82A is larger than the outer diameter of the stopper member 81. When attached to the main shaft portion 52 as shown in FIG. 2 , the washer 82A has a radial gap between its outer peripheral surface 82Aa and the inner peripheral surface 15a of the inner cylinder 15, which is located radially outward of the washer 82A. This gap is annular and follows the inner peripheral surface 15a of the inner cylinder 15. A passage 122 through which the oil L can flow is formed between the outer peripheral surface 82Aa of the washer 82A and the inner peripheral surface 15a of the inner cylinder 15. In other words, the washer 82A is formed to allow the oil L, as a working fluid, to flow between the radial outer periphery and the inner cylinder 15 of the cylinder 17.

[0091] A passage 123A (second passage) through which oil L can flow is formed between the vertical groove 101A provided on the inner peripheral surface 82Ab of the washer 82A and the outer peripheral surface 52a of the main shaft portion 52 of the piston rod 51. A passage 124A (third passage) through which oil L can flow is formed inside the horizontal hole 102A provided in the washer 82A. The washer 82A is in a free state with respect to the piston rod 51. The washer 82A may be fixed by fitting it to the main shaft portion 52 of the piston rod 51 with an interference.

[0092] An end surface 83d of an elastic member 83 similar to that provided in the impact absorbing mechanism 111 abuts against an end surface 82c of the washer 82A. The elastic member 83 abuts against the washer 82A, which in turn abuts against the stopper member 81, and thus moves together with the piston rod 51.

[0093] Here, the flow path area of ​​passage 123A between vertical groove 101A of washer 82A and main shaft portion 52 and passage 124A in horizontal hole 102A of washer 82A are formed to be larger than the flow path area of ​​passage 125 between elastic member 83 and inner tube 15 of cylinder 17. In addition, the flow path area of ​​passage 123A between vertical groove 101A of washer 82A and main shaft portion 52 and passage 124A in horizontal hole 102A of washer 82A are formed to be larger than the flow path area through damping force generating mechanisms 59, 60 (see FIG. 1) provided in piston 45 (see FIG. 1), specifically, the flow path area when damping force generating mechanisms 59, 60 (see FIG. 1) are fully open.

[0094] An axial tensile load is applied to shock absorber 11A, and piston rod 51 moves axially relative to cylinder 17 in the extension direction, which increases the overall length of shock absorber 11A. Then, shock absorbing mechanism 111A also moves together with piston rod 51 and approaches rod guide 28. At that time, oil L present between rod guide 28 and elastic member 83 of first chamber 48 flows between stopper member 81 of first chamber 48 and piston 45 (see FIG. 1 ) through passage 125 between outer peripheral surface 83 a of elastic member 83 and inner peripheral surface 15 a of inner cylinder 15, passage 122 between outer peripheral surface 82Aa of washer 82A and inner peripheral surface 15 a of inner cylinder 15, and passage 121 between outer peripheral end surface 81 b of stopper member 81 and inner peripheral surface 15 a of inner cylinder 15. At that time, the oil liquid L between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through a passage 126 between the inner surface 83b of the elastic member 83 and the outer surface 52a of the main shaft portion 52 of the piston rod 51, a passage 123A between the vertical groove 101A provided in the inner surface 82Ab of the washer 82A and the outer surface 52a of the main shaft portion 52 of the piston rod 51, a passage 124A in the horizontal hole 102A provided at the axial middle position of the washer 82A, a passage 122 between the outer surface 82Aa of the washer 82A and the inner surface 15a of the inner tube 15, and a passage 121 between the outer end surface 81b of the stopper member 81 and the inner surface 15a of the inner tube 15, and between the stopper member 81 of the first chamber 48 and the piston 45 (see Figure 1).

[0095] In other words, a passage 122 through which oil L as a working fluid can flow is formed between the radial outer peripheral surface 82Aa of the washer 82A and the inner tube 15 of the cylinder 17. Furthermore, a passage 123A through which oil L can flow is formed between the radial inner peripheral surface 82Ab of the washer 82A and the piston rod 51. Furthermore, a passage 124A that communicates with the passage 123A is provided in the washer 82A. The passage 124A formed by the horizontal hole 102A is formed in the washer 82A and is in phase with the passage 123A formed by the vertical groove 101A of the washer 82A.

[0096] During the extension stroke, as described above, the impact absorption mechanism 111A moves together with the piston rod 51 in a direction approaching the rod guide 28. At that time, the oil L present between the rod guide 28 and the elastic member 83 of the first chamber 48 flows through the passage 125 between the elastic member 83 and the inner cylinder 15, the passage 122 between the washer 82A and the inner cylinder 15, and the passage 121 between the stopper member 81 and the inner cylinder 15 to the side of the piston 45 (see FIG. 1 ) of the first chamber 48 that is closer to the stopper member 81. At the same time, the oil liquid L between the rod guide 28 of the first chamber 48 and the elastic member 83 passes through the passage 126 between the elastic member 83 and the piston rod 51, the passage 123A between the piston rod 51 and the washer 82A, the passage 124A within the washer 82A, the passage 122 between the washer 82A and the inner tube 15, and the passage 121 between the stopper member 81 and the inner tube 15, and flows toward the piston 45 (see Figure 1) side of the stopper member 81 of the first chamber 48.

[0097] As described above, in the shock absorber 11A of the second embodiment, the passage 122 through which the oil liquid L can flow is formed between the radial outer peripheral surface 82Aa of the washer 82A and the inner cylinder 15. In addition, in the shock absorber 11A, the passage 123A through which the oil liquid L can flow is formed between the radial inner peripheral surface 82Ab of the washer 82A and the piston rod 51. In addition, in the shock absorber 11A, the passage 124A that communicates with the passage 123A is provided in the washer 82A. Therefore, even if the moving speed of the piston rod 51 exceeds a predetermined value and the elastic member 83 deforms radially outward so as to be sucked into the passage 122, the oil L present between the rod guide 28 and the elastic member 83 in the first chamber 48 passes through the passage 126 between the elastic member 83 deformed radially outward and the piston rod 51, the passage 123A between the piston rod 51 and the washer 82A, the passage 124A in the washer 82A, the passage 122 between the washer 82A and the inner cylinder 15, and the passage 121 between the stopper member 81 and the inner cylinder 15, and flows smoothly between the stopper member 81 in the first chamber 48 and the piston 45 (see FIG. 1 ). This allows the shock absorber 11A, like the shock absorber 11, to suppress unnecessary increases in damping force that occur except at the maximum extension time. Therefore, the shock absorber 11A is able to generate a stable damping force.

[0098] Furthermore, the shock absorber 11A is provided with a washer 82A in addition to the elastic member 83, and the washer 82A is provided with passages 123A and 124A. Therefore, the shock absorber 11A can suppress the influence on the flexibility of selection of the elastic member 83.

[0099] Furthermore, in the shock absorber 11A, of the passages 123A and 124A, the passage 124A is formed in the horizontal hole 102A between both axial ends of the washer 82A. Therefore, in the shock absorber 11A, it is possible to eliminate the effect on the durability of the elastic member 83 caused by forming the passage 124A in the washer 82A.

[0100] Furthermore, in the shock absorber 11A, the passage 124A is formed in the washer 82A in the same phase as the passage 123A. This eliminates the need to align the phases of the passages 123A and 124A during assembly, making the shock absorber 11A easier to assemble.

[0101] Furthermore, the shock absorber 11A is formed so that the flow path area of ​​the passages 123A and 124A is larger than the flow path area of ​​the passage 125 between the elastic member 83 and the inner tube 15 of the cylinder 17. Therefore, the shock absorber 11A can further suppress the influence of the elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, the shock absorber 11A can generate a more stable damping force.

[0102] Furthermore, the shock absorber 11A is formed so that the flow path areas of the passages 123A and 124A are larger than the flow path area through the damping force generating mechanisms 59, 60 (see FIG. 1) provided in the piston 45 (see FIG. 1). Therefore, the shock absorber 11A can further suppress the influence of the elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, the shock absorber 11A can generate a more stable damping force.

[0103] Third Embodiment Next, a third embodiment will be described, focusing on 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.

[0104] In the shock absorber 11B of the third embodiment, a piston rod 51B that is partially different from the piston rod 51 is provided instead of the piston rod 51. The piston rod 51B has a main shaft portion 52B that is partially different from the main shaft portion 52 instead of the main shaft portion 52.

[0105] The outer peripheral surface 52Ba of the main shaft portion 52B has an outer peripheral end surface 52Baa and a communicating groove 151. The outer peripheral end surface 52Baa is cylindrical. The communicating groove 151 is recessed radially inward from the outer peripheral end surface 52Baa of the piston rod 51B. The communicating groove 151 extends in the axial direction of the piston rod 51B. The main shaft portion 52B has an engaging groove 85B formed therein, which is partially different from the engaging groove 85. The engaging groove 85B differs from the engaging groove 85 in that the communicating groove 151 runs vertically, forming a circular ring shape that is partially broken in the circumferential direction. The outer peripheral surface 52Ba is similar to the outer peripheral surface 52a except for the communicating groove 151. The communicating groove 151 may be formed in one location or multiple locations on the piston rod 51B. When forming a plurality of communication grooves 151 in the piston rod 51B, it is preferable to form the communication grooves 151 at equal intervals in the circumferential direction of the piston rod 51B by aligning the axial positions of the piston rod 51B.

[0106] The shock absorber 11B has an impact absorbing mechanism 111B that is partially different from the impact absorbing mechanism 111, instead of the impact absorbing mechanism 111. The impact absorbing mechanism 111B has a washer 82B that is partially different from the washer 82, instead of the washer 82. The washer 82B differs from the washer 82 in that the longitudinal groove 101 and the lateral groove 102 are not formed.

[0107] The washer 82B is made of the same synthetic resin as the washer 82. The washer 82B has an outer peripheral surface 82Ba on the radially outer side, an inner peripheral surface 82Bb on the radially inner side, an end face 82Bc on one axial side, and an end face 82Bd on the other axial side. The outer peripheral surface 82Ba has an outer peripheral end face 82Baa and, similar to the washer 82, outer peripheral tapered surfaces 82ab and 82Bac.

[0108] The outer peripheral end surface 82Baa has a cylindrical surface shape.

[0109] The outer peripheral tapered surface 82ab is continuous with the outer peripheral end surface 82Baa and the end surface 82Bc. The outer peripheral tapered surface 82ab has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82Baa in the axial direction of the outer peripheral surface 82Ba.

[0110] The outer peripheral tapered surface 82Bac is continuous with the outer peripheral end surface 82Baa and the end surface 82Bd. The outer peripheral tapered surface 82Bac has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82Baa in the axial direction of the outer peripheral surface 82Ba.

[0111] The inner peripheral surface 82Bb is cylindrical and is disposed coaxially with the outer peripheral surface 82Ba.

[0112] The end surface 82Bc is a flat surface extending perpendicular to the central axes of the outer peripheral surface 82Ba and the inner peripheral surface 82Bb, and is continuous with the outer peripheral tapered surface 82ab and the inner peripheral surface 82Bb.

[0113] The end surface 82Bd is a flat surface extending perpendicular to the central axis of the outer peripheral surface 82Ba and the inner peripheral surface 82Bb. The end surface 82Bd is parallel to the end surface 82Bc and faces away from the end surface 82Bc. The end surface 82Bd is continuous with the outer peripheral tapered surface 82Bac and the inner peripheral surface 82Bb.

[0114] The impact cushioning mechanism 111B has a stopper member 81 similar to that provided in the impact cushioning mechanism 111, with the piston rod 51B inserted inside its inner circumferential surface 81c. The stopper member 81 is fitted onto the outer circumferential end surface 52Baa of the piston rod 51B in the stopper main body 91, and is fixed to the piston rod 51B via the locking ring 80 engaged with the engagement groove 85B, in the same manner as in the first embodiment.

[0115] The main shaft portion 52B of the piston rod 51B is inserted into the radially inner side of the washer 82B, and an end face 82Bd of the washer 82B abuts against the end face 81a of the stopper member 81. The washer 82B is also free relative to the piston rod 51. The washer 82B may be fixed by fitting it to the main shaft portion 52B of the piston rod 51 with an interference.

[0116] The outer diameter of the washer 82B is smaller than the inner diameter of the inner cylinder 15. That is, the diameter of the outer peripheral end surface 82Baa of the washer 82B is smaller than the diameter of the inner peripheral surface 15a of the inner cylinder 15. The outer diameter of the washer 82B is larger than the outer diameter of the stopper member 81. When the washer 82B is attached to the main shaft portion 52 as shown in FIG. 4 , a radial gap is formed between the outer peripheral surface 82Ba of the washer 82B and the inner peripheral surface 15a of the inner cylinder 15, which is disposed radially outward of the washer 82B. This gap is annular and follows the inner peripheral surface 15a of the inner cylinder 15. A passage 122 through which the oil L can flow is formed between the outer peripheral surface 82Ba of the washer 82B and the inner peripheral surface 15a of the inner cylinder 15. In other words, the washer 82B is formed to allow the oil L, as a working fluid, to flow between the radial outer periphery and the inner cylinder 15 of the cylinder 17.

[0117] An end surface 83d of an elastic member 83 similar to that provided in the impact absorbing mechanism 111 abuts against an end surface 82Bc of the washer 82B. The elastic member 83 abuts against the washer 82B, which in turn abuts against the stopper member 81, and thus moves together with the piston rod 51B.

[0118] The communicating groove 151 of the piston rod 51B is formed in a position in the axial direction of the piston rod 51B that crosses the impact absorption mechanism 111B of the main shaft portion 52B. In other words, one end of the communicating groove 151 in the axial direction of the piston rod 51B is closer to the rod guide 28 than the impact absorption mechanism 111B, and the other end of the communicating groove 151 in the axial direction of the piston rod 51B is closer to the rod guide 28 than the impact absorption mechanism 111B. As a result, the communicating groove 151 of the main shaft portion 52B forms a passage 126B through which the oil L can flow between the communicating groove 151 and the inner circumferential surface 83b of the elastic member 83. Furthermore, the communicating groove 151 of the main shaft portion 52B forms a passage 123B through which the oil L can flow between the communicating groove 151 and the inner circumferential surface 82Bb of the washer 82B. Furthermore, the communicating groove 151 of the main shaft portion 52B forms a passage 124B through which the oil L can flow between the communicating groove 151 and the inner circumferential surface 81c of the stopper member 81.

[0119] Here, the flow path area of ​​passage 123B between washer 82B and communicating groove 151 of main shaft portion 52B and passage 124B between stopper member 81 and communicating groove 151 of main shaft portion 52B are formed to be larger than the flow path area of ​​passage 125 between elastic member 83 and inner tube 15 of cylinder 17. In addition, the flow path area of ​​passage 123B between washer 82B and communicating groove 151 of main shaft portion 52B and passage 124B between stopper member 81 and communicating groove 151 of main shaft portion 52B are formed to be larger than the flow path area through damping force generation mechanisms 59, 60 (see FIG. 1) provided in piston 45 (see FIG. 1), specifically the flow path area when the damping force generation mechanisms 59, 60 (see FIG. 1) are fully open.

[0120] An axial tensile load is applied to shock absorber 11B, and piston rod 51B moves axially relative to cylinder 17 in the extension direction, which increases the overall length of shock absorber 11B. Then, shock absorbing mechanism 111B also moves together with piston rod 51B and approaches rod guide 28. At that time, oil L present between rod guide 28 of first chamber 48 and elastic member 83 flows between stopper member 81 of first chamber 48 and piston 45 (see FIG. 1 ) through passage 125 between outer peripheral surface 83 a of elastic member 83 and inner peripheral surface 15 a of inner cylinder 15, passage 122 between outer peripheral surface 82Ba of washer 82B and inner peripheral surface 15 a of inner cylinder 15, and passage 121 between outer peripheral end surface 81 b of stopper member 81 and inner peripheral surface 15 a of inner cylinder 15. At that time, the oil liquid L between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through passage 126B between the inner surface 83b of the elastic member 83 and the communicating groove 151 of the main shaft portion 52B of the piston rod 51B, passage 123B between the inner surface 82Bb of the washer 82B and the communicating groove 151 of the main shaft portion 52B, and passage 124B between the inner surface 81c of the stopper member 81 and the communicating groove 151 of the main shaft portion 52B, and flows between the stopper member 81 of the first chamber 48 and the piston 45 (see Figure 1).

[0121] In other words, a passage 122 through which oil L as a working fluid can flow is formed between the radial outer peripheral surface 82Ba of the washer 82B and the inner tube 15 of the cylinder 17. Furthermore, a passage 123B through which oil L can flow is formed between the radial inner peripheral surface 82Bb of the washer 82B and the piston rod 51B. Furthermore, a passage 124B that communicates with passage 123B is provided in the stopper member 81. Passages 123B, 124B, and 126B are defined by a communicating groove 151 formed in the piston rod 51B.

[0122] During the extension stroke, as described above, the shock absorbing mechanism 111B moves together with the piston rod 51B in a direction approaching the rod guide 28. At that time, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through the passage 125 between the elastic member 83 and the inner cylinder 15, the passage 122 between the washer 82B and the inner cylinder 15, and the passage 121 between the stopper member 81 and the inner cylinder 15, toward the piston 45 (see FIG. 1 ) side of the stopper member 81 of the first chamber 48. At the same time, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through the passage 126B between the elastic member 83 and the piston rod 51B, the passage 123B between the piston rod 51B and the washer 82B, and the passage 124B between the piston rod 51B and the stopper member 81, toward the piston 45 (see FIG. 1 ) side of the stopper member 81 of the first chamber 48.

[0123] As described above, in the shock absorber 11B of the third embodiment, the passage 122 through which the oil liquid L can flow is formed between the radial outer peripheral surface 82Ba of the washer 82B and the inner cylinder 15. In addition, in the shock absorber 11B, the passage 123B through which the oil liquid L can flow is formed between the radial inner peripheral surface 82Bb of the washer 82B and the piston rod 51B. In addition, in the shock absorber 11B, the passage 124B that communicates with the passage 123B is provided in the stopper member 81. Therefore, in the shock absorber 11B, even if the moving speed of the piston rod 51B exceeds a predetermined value and the elastic member 83 deforms radially outward so as to be sucked into the passage 122, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows smoothly between the stopper member 81 of the first chamber 48 and the piston 45 (see FIG. 1 ) through the passage 126B between the elastic member 83 deformed radially outward and the piston rod 51B, the passage 123B between the piston rod 51B and the washer 82B, and the passage 124B between the piston rod 51B and the stopper member 81. As a result, the shock absorber 11B, like the shock absorber 11, can suppress an unnecessary increase in damping force that occurs except at the time of maximum extension. Therefore, the shock absorber 11B can generate a stable damping force.

[0124] Furthermore, in the shock absorber 11B, the passages 123B, 124B, and 126B are formed in the piston rod 51B. This eliminates the need for phase alignment between the passages 123B, 124B, and 126B during assembly, making the shock absorber 11B easier to assemble.

[0125] Furthermore, the shock absorber 11B is formed so that the flow path area of ​​the passages 123B and 124B is larger than the flow path area of ​​the passage 125 between the elastic member 83 and the inner tube 15 of the cylinder 17. Therefore, the shock absorber 11B can further suppress the influence of the elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, the shock absorber 11B can generate a more stable damping force.

[0126] Furthermore, the shock absorber 11B is formed so that the flow path areas of the passages 123B and 124B are larger than the flow path area through the damping force generating mechanisms 59, 60 (see FIG. 1) provided in the piston 45 (see FIG. 1). Therefore, the shock absorber 11B can further suppress the influence on the damping force by the elastic member 83 that occurs at times other than the maximum extension. Therefore, the shock absorber 11B can generate a more stable damping force.

[0127] [Fourth Embodiment] Next, a fourth embodiment will be described, focusing on differences from the first embodiment, mainly with reference to Fig. 5. Note that parts common to the first embodiment will be designated by the same names and reference numerals.

[0128] A shock absorber 11C of the fourth embodiment has an impact absorbing mechanism 111C that is partially different from the impact absorbing mechanism 111, instead of the impact absorbing mechanism 111. The impact absorbing mechanism 111C has a stopper member 81C that is partially different from the stopper member 81, instead of the stopper member 81. The impact absorbing mechanism 111C has a washer 82C that is partially different from the washer 82, instead of the washer 82.

[0129] The stopper member 81C is made of metal and has a circular ring shape. The stopper member 81C has an inner peripheral surface 81Cc that has an inner peripheral end surface 81Cca and a vertical groove 161.

[0130] The inner peripheral end surface 81Cca has a cylindrical surface shape that is discontinuous in the circumferential direction of the stopper member 81C. The inner peripheral end surface 81Cca is arranged coaxially with the outer peripheral end surface 81b. The stopper member 81C is formed with a vertical groove 161 that is recessed radially outward from the fractured portion of the inner peripheral end surface 81Cca. The vertical groove 161 extends linearly in the axial direction of the stopper member 81C and penetrates the stopper member 81C in the axial direction of the stopper member 81C. The stopper member 81C has multiple vertical grooves 161 of the same shape formed at equal intervals in the circumferential direction of the stopper member 81C. The stopper member 81C differs from the stopper member 81 in that it has the vertical groove 161.

[0131] The stopper member 81C has a stopper main body 91C in place of the stopper main body 91, which differs from the stopper main body 91 in that it has a vertical groove 161 formed therein. The stopper member 81C has a cylindrical engaging portion 92C in place of the cylindrical engaging portion 92, which differs from the cylindrical engaging portion 92 in that it has a vertical groove 161 formed therein. The stopper member 81C has an end face 81Ca in place of the end face 81a, which differs from the end face 81a in that the vertical groove 161 opens thereto.

[0132] The main shaft portion 52 of the piston rod 51 is inserted through the outer peripheral surface 52a of the stopper member 81C, inside the radial inner peripheral end surface 81Cca. At this time, the stopper member 81C is fitted onto the main shaft portion 52 of the piston rod 51 at its stopper main body portion 91C. At this time, the stopper member 81C is positioned such that the stopper main body portion 91C is closer to the rod guide 28 than the cylindrical engaging portion 92C in the axial direction. The cylindrical engaging portion 92C of the stopper member 81C is cylindrical before attachment to the piston rod 51. The locking ring 80 is disposed radially inside the cylindrical engaging portion 92C. In this state, the cylindrical engaging portion 92C is crimped radially inward and plastically deformed. At this time, the cylindrical engaging portion 92C is plastically deformed in the circumferential direction except for the portion where the longitudinal groove 161 is formed. As a result, the cylindrical engaging portion 92C restricts the radial expansion of the locking ring 80. At the same time, the stopper main body 91C and the cylindrical engaging portion 92C, i.e., the stopper member 81C, are restricted from axial movement relative to the piston rod 51 by the locking ring 80. The stopper member 81C is fixed to the piston rod 51 by the cylindrical engaging portion 92C being pressed against the outer peripheral surface 52a of the main shaft portion 52.

[0133] 5 , when the stopper member 81C is attached to the piston rod 51, a radial gap is formed between its outer circumferential end surface 81b and the inner circumferential surface 15a of the inner cylinder 15 located radially outward of the stopper member 81C. This gap is annular and follows the inner circumferential surface 15a of the inner cylinder 15. A passage 121 through which oil L can flow is formed between the outer circumferential end surface 81b of the stopper member 81C and the inner circumferential surface 15a of the inner cylinder 15. In other words, the stopper member 81C is formed so that oil L, as a working fluid, can flow between the radial outer periphery and the inner cylinder 15 of the cylinder 17.

[0134] The washer 82C is made of the same synthetic resin as the washer 82. The washer 82C has an outer peripheral surface 82Ca on the radially outer side, an inner peripheral surface 82Cb on the radially inner side, an end face 82c on one axial side similar to that of the washer 82, and an end face 82Cd on the other axial side. The outer peripheral surface 82Ca has an outer peripheral end face 82Caa, and outer peripheral tapered surfaces 82ab and 82Cac similar to those of the washer 82. The inner peripheral surface 82Cb has an inner peripheral end face 82ba and a longitudinal groove 101C similar to those of the washer 82.

[0135] The outer peripheral end surface 82Caa has a cylindrical surface shape.

[0136] The outer peripheral tapered surface 82ab is continuous with the outer peripheral end surface 82Caa and the end surface 82c. The outer peripheral tapered surface 82ab has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82Caa in the axial direction of the outer peripheral surface 82Ca.

[0137] The outer peripheral tapered surface 82Cac is continuous with the outer peripheral end surface 82Caa and the end surface 82Cd. The outer peripheral tapered surface 82Cac has a tapered surface shape that decreases in diameter as it moves away from the outer peripheral end surface 82Caa in the axial direction of the outer peripheral surface 82Ca.

[0138] The inner peripheral end surface 82ba is disposed coaxially with the outer peripheral surface 82Ca. The washer 82C is formed with a longitudinal groove 101C that extends from the fractured portion of the inner peripheral end surface 82ba toward the radially outward direction of the washer 82C. The longitudinal groove 101C extends linearly in the axial direction of the washer 82C and penetrates the washer 82C in the axial direction of the washer 82C. For example, the longitudinal groove 101C has an arc-shaped cross section in a plane extending perpendicular to its extension direction. In other words, the width of the longitudinal groove 101C in the circumferential direction of the washer 82C narrows toward the radially outward direction of the washer 82C. The washer 82C is formed with the same number of longitudinal grooves 101C as the longitudinal grooves 161 of the stopper member 81C, spaced at equal intervals along the circumferential direction of the washer 82C.

[0139] The end surface 82c is a flat surface extending perpendicular to the central axis of the outer peripheral surface 82Ca and the inner peripheral surface 82Cb. The end surface 82c is continuous with the inner peripheral end surface 82ba.

[0140] The end surface 82Cd is a flat surface extending perpendicular to the central axis of the outer peripheral surface 82Ca and the inner peripheral surface 82Cb. The end surface 82Cd is parallel to the end surface 82c and faces away from the end surface 82c. The end surface 82Cd is continuous with the outer peripheral tapered surface 82Cac and the inner peripheral end surface 82ba.

[0141] The longitudinal groove 101C has one end in the axial direction of the washer 82C that opens to the end face 82c, and the other end that opens to the end face 82Cd.

[0142] The main shaft portion 52 of the piston rod 51 is fitted into the radially inner side of the washer 82C, and an end face 82Cd of the washer 82C abuts against an end face 81Ca of the stopper member 81C. The washer 82C is fitted and fixed to the main shaft portion 52 of the piston rod 51 with an interference. At this time, the washer 82C is attached to the main shaft portion 52 such that the phases of the multiple vertical grooves 101C of the washer 82C and the stopper member 81C in the circumferential direction are aligned with the multiple vertical grooves 161 of the stopper member 81C. In other words, the multiple vertical grooves 101C and the multiple vertical grooves 161 correspond one-to-one and are aligned in phase and communicate with each other.

[0143] Note that a recessed portion may be formed on the inner peripheral side of the end face 81Ca of the stopper member 81C, forming an annular shape in the circumferential direction of the stopper member 81C and connecting the plurality of vertical grooves 161, and this recessed portion may be connected to the plurality of vertical grooves 101C of the washer 82C, thereby eliminating the need to align the phases of the plurality of vertical grooves 101C with the plurality of vertical grooves 161. Alternatively, a recessed portion may be formed on the inner peripheral side of the end face 82Cd of the washer 82C, forming an annular shape in the circumferential direction of the washer 82C and connecting the plurality of vertical grooves 101C, and this recessed portion may be connected to the plurality of vertical grooves 161 of the stopper member 81C, thereby eliminating the need to align the phases of the plurality of vertical grooves 101C with the plurality of vertical grooves 161. In either of these cases, the washer 82C can be placed in a free state without being fitted to the main shaft portion 52 of the piston rod 51 with any interference.

[0144] The outer diameter of the washer 82C is smaller than the inner diameter of the inner cylinder 15. That is, the diameter of the outer peripheral end surface 82Caa of the washer 82C is smaller than the diameter of the inner peripheral surface 15a of the inner cylinder 15. The outer diameter of the washer 82C is larger than the outer diameter of the stopper member 81. When attached to the main shaft portion 52 as shown in FIG. 5 , the washer 82C has a radial gap between its outer peripheral surface 82Ca and the inner peripheral surface 15a of the inner cylinder 15, which is located radially outward of the washer 82C. This gap is annular and follows the inner peripheral surface 15a of the inner cylinder 15. A passage 122 through which the oil L can flow is formed between the outer peripheral surface 82Ca of the washer 82C and the inner peripheral surface 15a of the inner cylinder 15. In other words, the washer 82C is formed to allow the oil L, as a working fluid, to flow between the radial outer periphery and the inner cylinder 15 of the cylinder 17.

[0145] A passage 123C (second passage) through which oil L can flow is formed between the vertical groove 101C provided on the inner peripheral surface 82Cb of the washer 82C and the outer peripheral surface 52a of the main shaft portion 52 of the piston rod 51. A passage 124C (third passage) through which oil L can flow is formed between the vertical groove 161 provided on the inner peripheral surface 81Cc of the stopper member 81C and the outer peripheral surface 52a of the main shaft portion 52 of the piston rod 51.

[0146] An end surface 83d of an elastic member 83 similar to that provided in the impact absorption mechanism 111 abuts against the end surface 82c of the washer 82C. The elastic member 83 moves together with the piston rod 51 by abutting against the washer 82C.

[0147] Here, the flow path area of ​​passage 123C between vertical groove 101C of washer 82C and main shaft portion 52 and passage 124C between vertical groove 161 of stopper member 81C and main shaft portion 52 are formed to be larger than the flow path area of ​​passage 125 between elastic member 83 and inner tube 15 of cylinder 17. In addition, the flow path area of ​​passage 123C between vertical groove 101C of washer 82C and main shaft portion 52 and passage 124C between vertical groove 161 of stopper member 81C and main shaft portion 52 are formed to be larger than the flow path area through damping force generating mechanisms 59, 60 (see FIG. 1) provided in piston 45 (see FIG. 1), specifically, the flow path area when damping force generating mechanisms 59, 60 (see FIG. 1) are fully open.

[0148] An axial tensile load is applied to shock absorber 11C, and piston rod 51 moves axially relative to cylinder 17 in the extension direction, which increases the overall length of shock absorber 11C. Then, shock absorbing mechanism 111C also moves together with piston rod 51 and approaches rod guide 28. At that time, oil L present between rod guide 28 and elastic member 83 of first chamber 48 flows between stopper member 81C of first chamber 48 and piston 45 (see FIG. 1 ) through passage 125 between outer peripheral surface 83a of elastic member 83 and inner peripheral surface 15a of inner cylinder 15, passage 122 between outer peripheral surface 82Ca of washer 82C and inner peripheral surface 15a of inner cylinder 15, and passage 121 between outer peripheral end surface 81b of stopper member 81C and inner peripheral surface 15a of inner cylinder 15. At that time, the oil liquid L between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through a passage 126 between the inner surface 83b of the elastic member 83 and the outer surface 52a of the main shaft portion 52 of the piston rod 51, a passage 123C between the vertical groove 101C provided on the inner surface 82Cb of the washer 82C and the outer surface 52a of the main shaft portion 52 of the piston rod 51, and a passage 124C between the vertical groove 161 provided on the inner surface 81Cb of the stopper member 81C and the outer surface 52a of the main shaft portion 52 of the piston rod 51, and between the stopper member 81C of the first chamber 48 and the piston 45 (see Figure 1).

[0149] In other words, a passage 122 through which oil L as a working fluid can flow is formed between the radial outer peripheral surface 82Ca of the washer 82C and the inner tube 15 of the cylinder 17. Furthermore, a passage 123C through which oil L can flow is formed between the radial inner peripheral surface 82Cb of the washer 82C and the piston rod 51. Furthermore, a passage 124C that communicates with the passage 123C is provided in the stopper member 81C.

[0150] During the extension stroke, as described above, the impact absorption mechanism 111C moves together with the piston rod 51 in a direction approaching the rod guide 28. At that time, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through the passage 125 between the elastic member 83 and the inner cylinder 15, the passage 122 between the washer 82C and the inner cylinder 15, and the passage 121 between the stopper member 81C and the inner cylinder 15, toward the piston 45 (see FIG. 1 ) side of the stopper member 81C of the first chamber 48. At the same time, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through the passage 126 between the elastic member 83 and the piston rod 51, the passage 123C between the piston rod 51 and the washer 82C, and the passage 124C between the piston rod 51 and the stopper member 81C, toward the piston 45 (see FIG. 1 ) side of the stopper member 81C of the first chamber 48.

[0151] As described above, in the shock absorber 11C of the fourth embodiment, the passage 122 through which the oil liquid L can flow is formed between the radial outer peripheral surface 82Ca of the washer 82C and the inner cylinder 15. Furthermore, in the shock absorber 11C, the passage 123C through which the oil liquid L can flow is formed between the radial inner peripheral surface 82Cb of the washer 82C and the piston rod 51. Furthermore, in the shock absorber 11C, the passage 124C that communicates with the passage 123C is provided in the stopper member 81C. Therefore, in the shock absorber 11C, even if the moving speed of the piston rod 51 exceeds a predetermined value and the elastic member 83 deforms radially outward so as to be sucked into the passage 122, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows smoothly through the passage 126 between the elastic member 83 deformed radially outward and the piston rod 51, the passage 123C between the piston rod 51 and the washer 82C, and the passage 124C between the piston rod 51 and the stopper member 81C, between the stopper member 81C of the first chamber 48 and the piston 45 (see FIG. 1). As a result, the shock absorber 11C, like the shock absorber 11, can suppress an unnecessary increase in damping force that occurs except at the time of maximum extension. Therefore, the shock absorber 11C can generate a stable damping force.

[0152] Furthermore, the shock absorber 11C is provided with a washer 82C separate from the elastic member 83, with a passage 123C provided in the washer 82C, and with a passage 124C provided in a stopper member 81C separate from the elastic member 83. Therefore, the shock absorber 11C can suppress the influence on the flexibility of selection of the elastic member 83.

[0153] Furthermore, in the shock absorber 11C, of ​​the passages 123C and 124C, the passage 124C is formed in the stopper member 81C. Therefore, in the shock absorber 11C, it is possible to eliminate the effect of the formation of the passage 124C on the durability of the elastic member 83 that is arranged on the opposite side of the washer 82C from the stopper member 81C.

[0154] Furthermore, the shock absorber 11C is formed so that the flow path area of ​​the passages 123C and 124C is larger than the flow path area of ​​the passage 125 between the elastic member 83 and the inner tube 15 of the cylinder 17. Therefore, the shock absorber 11C can further suppress the influence of the elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, the shock absorber 11C can generate a more stable damping force.

[0155] Furthermore, the shock absorber 11C is formed so that the flow path areas of the passages 123C and 124C are larger than the flow path area of ​​the damping force generating mechanisms 59, 60 (see FIG. 1) provided in the piston 45 (see FIG. 1). Therefore, the shock absorber 11C can further suppress the influence of the elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, the shock absorber 11C can generate a more stable damping force.

[0156] Fifth Embodiment Next, a fifth embodiment will be described, focusing on differences from the first and fourth embodiments, mainly with reference to Fig. 6. Note that parts common to the first and fourth embodiments will be designated by the same names and symbols.

[0157] The shock absorber 11D of the fifth embodiment has an impact absorbing mechanism 111D that is partially different from the impact absorbing mechanism 111C instead of the impact absorbing mechanism 111C. The impact absorbing mechanism 111D has a stopper member 81D that is partially different from the stopper member 81C instead of the stopper member 81C. The impact absorbing mechanism 111D has a washer 82C similar to the impact absorbing mechanism 111C.

[0158] The stopper member 81D is made of metal and has a circular ring shape. The stopper member 81D has an end side surface 81Da on one axial side, which has an end surface 81Daa (abutment surface) and a lateral groove 171.

[0159] The end surface 82Daa extends perpendicular to the central axis of the stopper member 81D and has a planar shape that is discontinuous in the circumferential direction of the stopper member 81D. The stopper member 81D is formed with a lateral groove 171 that is recessed inward in the axial direction of the stopper member 81D from the broken portion of the end surface 82Daa. The lateral groove 171 extends linearly in the radial direction of the stopper member 81D and penetrates the stopper member 81D in the radial direction of the stopper member 81D. The stopper member 81D has the same shaped lateral grooves 171 formed at equal intervals in the circumferential direction of the stopper member 81D, and the same number as the multiple vertical grooves 101C of the washer 82C. The stopper member 81D differs from the stopper member 81 in that the lateral grooves 171 are formed.

[0160] The stopper member 81D has a stopper main body 91D instead of the stopper main body 91, which differs from the stopper main body 91 in that the lateral groove 171 is formed therein. The stopper member 81D has an inner circumferential surface 81Dc instead of the inner circumferential surface 81c, which differs from the inner circumferential surface 81c in that the lateral groove 171 opens therein. The stopper member 81D has an outer circumferential end surface 81Db instead of the outer circumferential end surface 81b, which differs from the outer circumferential end surface 81b in that the lateral groove 171 opens therein.

[0161] The main shaft portion 52 of the piston rod 51 is inserted into the inner circumferential surface 81Dc of the stopper member 81D. At this time, the main shaft portion 52 of the piston rod 51 is fitted to the stopper main body portion 91D at the outer circumferential surface 52a of the stopper member 81D. At this time, the stopper main body portion 91D of the stopper member 81D is positioned closer to the rod guide 28 than the cylindrical engaging portion 92 in the axial direction. As in the first embodiment, the stopper member 81D is plastically deformed by crimping the cylindrical engaging portion 92 radially inward with the locking ring 80 disposed radially inside the cylindrical engaging portion 92. This causes the cylindrical engaging portion 92 to restrict radial expansion of the locking ring 80. At the same time, the axial movement of the stopper main body portion 91D and the cylindrical engaging portion 92, i.e., the stopper member 81D, relative to the piston rod 51 is restricted by the locking ring 80. The stopper member 81D is fixed to the piston rod 51 by the cylindrical engaging portion 92 being pressed against the outer circumferential surface 52a of the main shaft portion 52.

[0162] 6 , when the stopper member 81D is attached to the piston rod 51, a radial gap is formed between its outer circumferential end surface 81Db and the inner circumferential surface 15a of the inner cylinder 15 located radially outward of the stopper member 81D. This gap is annular and follows the inner circumferential surface 15a of the inner cylinder 15. A passage 121 through which oil L can flow is formed between the outer circumferential end surface 81Db of the stopper member 81D and the inner circumferential surface 15a of the inner cylinder 15. In other words, the stopper member 81D is formed so that oil L, as a working fluid, can flow between the radial outer periphery and the inner cylinder 15 of the cylinder 17.

[0163] The main shaft portion 52 of the piston rod 51 is fitted into the radially inner side of the washer 82C, and an end face 82Cd of the washer 82C abuts against an end face 81Daa of the stopper member 81D. The washer 82C is fitted and fixed to the main shaft portion 52 of the piston rod 51 with an interference. At this time, the washer 82C is attached to the main shaft portion 52 such that the phases of the multiple vertical grooves 101C of the washer 82C and the stopper member 81D in the circumferential direction are aligned with the multiple horizontal grooves 171 of the stopper member 81D. In other words, the multiple vertical grooves 101C and the multiple horizontal grooves 171 that correspond one-to-one are aligned in phase and communicate with each other.

[0164] Note that a recessed portion may be formed on the inner peripheral side of the end face 81Daa of the stopper member 81D, forming an annular portion in the circumferential direction of the stopper member 81D and connecting the multiple lateral grooves 171, and this recessed portion may be connected to the multiple vertical grooves 101C of the washer 82C, thereby eliminating the need to align the phases of the multiple vertical grooves 101C and the multiple lateral grooves 171. Alternatively, a recessed portion may be formed on the inner peripheral side of the end face 82Cd of the washer 82C, forming an annular portion in the circumferential direction of the washer 82C and connecting the multiple vertical grooves 101C, and this recessed portion may be connected to the multiple lateral grooves 171 of the stopper member 81D, thereby eliminating the need to align the phases of the multiple vertical grooves 101C and the multiple lateral grooves 171. In either of these cases, the washer 82C can be placed in a free state without being fitted to the main shaft portion 52 of the piston rod 51 with any interference.

[0165] A passage 124D (third passage) through which the oil L can flow is formed between the lateral groove 171 provided on the end surface Daa of the stopper member 81D and the end surface 82Cd of the washer 82C.

[0166] An end surface 83d of an elastic member 83 similar to that provided in the impact absorption mechanism 111 abuts against the end surface 82c of the washer 82C. The elastic member 83 moves together with the piston rod 51 by abutting against the washer 82C.

[0167] Here, the flow path area of ​​a passage 123C between the vertical groove 101C of washer 82C and the main shaft portion 52 and a passage 124D between the lateral groove 171 of stopper member 81D and the washer 82C are formed to be larger than the flow path area of ​​a passage 125 between the elastic member 83 and the inner tube 15 of the cylinder 17. In addition, the flow path area of ​​the passage 123C between the vertical groove 101C of washer 82C and the main shaft portion 52 and the flow path area of ​​the passage 124D between the lateral groove 171 of stopper member 81D and the washer 82C are formed to be larger than the flow path area through the damping force generating mechanisms 59, 60 (see FIG. 1) provided in the piston 45 (see FIG. 1), specifically, the flow path area when the damping force generating mechanisms 59, 60 (see FIG. 1) are fully open.

[0168] An axial tensile load is applied to shock absorber 11D, and piston rod 51 moves axially relative to cylinder 17 in the extension direction, which increases the overall length of shock absorber 11D. Then, shock absorber mechanism 111D also moves together with piston rod 51 and approaches rod guide 28. At that time, oil L present between rod guide 28 of first chamber 48 and elastic member 83 flows between stopper member 81D of first chamber 48 and piston 45 (see FIG. 1 ) through passage 125 between outer peripheral surface 83a of elastic member 83 and inner peripheral surface 15a of inner cylinder 15, passage 122 between outer peripheral surface 82Ca of washer 82C and inner peripheral surface 15a of inner cylinder 15, and passage 121 between outer peripheral end surface 81Db of stopper member 81D and inner peripheral surface 15a of inner cylinder 15. At that time, the oil liquid L between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through a passage 126 between the inner surface 83b of the elastic member 83 and the outer surface 52a of the main shaft portion 52 of the piston rod 51, a passage 123C between the vertical groove 101C provided on the inner surface 82Cb of the washer 82C and the outer surface 52a of the main shaft portion 52 of the piston rod 51, and a passage 124D between the horizontal groove 171 provided on the end side surface 81Da of the stopper member 81D and the end face 82Cd of the washer 82C, and between the stopper member 81D of the first chamber 48 and the piston 45 (see Figure 1).

[0169] In other words, a passage 122 through which oil L as a working fluid can flow is formed between the radial outer peripheral surface 82Ca of the washer 82C and the inner tube 15 of the cylinder 17. Furthermore, a passage 123C through which oil L can flow is formed between the radial inner peripheral surface 82Cb of the washer 82C and the piston rod 51. Furthermore, a passage 124D communicating with the passage 123C is provided in the stopper member 81D.

[0170] During the extension stroke, as described above, the impact absorption mechanism 111D moves together with the piston rod 51 in a direction approaching the rod guide 28. At that time, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through the passage 125 between the elastic member 83 and the inner cylinder 15, the passage 122 between the washer 82C and the inner cylinder 15, and the passage 121 between the stopper member 81D and the inner cylinder 15, toward the piston 45 (see FIG. 1 ) side of the stopper member 81D of the first chamber 48. At the same time, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows through the passage 126 between the elastic member 83 and the piston rod 51, the passage 123C between the piston rod 51 and the washer 82C, and the passage 124D between the stopper member 81D and the washer 82C, toward the piston 45 (see FIG. 1 ) side of the stopper member 81D of the first chamber 48.

[0171] As described above, in the shock absorber 11D of the fifth embodiment, the passage 122 through which the oil liquid L can flow is formed between the radial outer peripheral surface 82Ca of the washer 82C and the inner cylinder 15. In addition, in the shock absorber 11D, the passage 123C through which the oil liquid L can flow is formed between the radial inner peripheral surface 82Cb of the washer 82C and the piston rod 51. In addition, in the shock absorber 11D, the passage 124D that communicates with the passage 123C is provided in the stopper member 81D. Therefore, in the shock absorber 11D, even if the moving speed of the piston rod 51 exceeds a predetermined value and the elastic member 83 deforms radially outward so as to be sucked into the passage 122, the oil L present between the rod guide 28 of the first chamber 48 and the elastic member 83 flows smoothly through the passage 126 between the elastic member 83 deformed radially outward and the piston rod 51, the passage 123C between the piston rod 51 and the washer 82C, and the passage 124D between the washer 82C and the stopper member 81D, and between the stopper member 81D of the first chamber 48 and the piston 45 (see FIG. 1). As a result, the shock absorber 11D, like the shock absorber 11, can suppress an unnecessary increase in damping force that occurs except at the maximum extension time. Therefore, the shock absorber 11D can generate a stable damping force.

[0172] Furthermore, the shock absorber 11D is provided with a washer 82C separate from the elastic member 83, with a passage 123C provided in the washer 82C, and with a passage 124D provided in the stopper member 81D separate from the elastic member 83. Therefore, the shock absorber 11D can suppress the influence on the flexibility of selection of the elastic member 83.

[0173] Furthermore, in shock absorber 11D, of passages 123C and 124D, passage 124D is formed in stopper member 81D. Therefore, in shock absorber 11D, it is possible to eliminate the effect of forming passage 124D on the durability of elastic member 83, which is arranged on the opposite side of washer 82C from stopper member 81D.

[0174] In addition, in the shock absorber 11D, of the passages 123C and 124D, the passage 124D is formed in the end surface 81Daa of the stopper member 81D, which is the abutment surface between the washer 82C and the stopper member 81D. Therefore, in the shock absorber 11D, the passage 124D can be easily formed.

[0175] Furthermore, shock absorber 11D is formed so that the flow path area of ​​passage 123C and passage 124D is larger than the flow path area of ​​passage 125 between elastic member 83 and inner tube 15 of cylinder 17. Therefore, shock absorber 11D can further suppress the influence of elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, shock absorber 11D can generate a more stable damping force.

[0176] Furthermore, the shock absorber 11D is formed so that the flow path areas of the passages 123C and 124D are larger than the flow path area of ​​the damping force generating mechanisms 59, 60 (see FIG. 1) provided in the piston 45 (see FIG. 1). Therefore, the shock absorber 11D can further suppress the influence of the elastic member 83 on the damping force that occurs at times other than the maximum extension. Therefore, the shock absorber 11D can generate a more stable damping force.

[0177] According to the shock absorber of the above aspect of the present invention, it is possible to generate a stable damping force, and therefore the shock absorber has great industrial applicability.

[0178] 11, 11A to 11D... shock absorber, 17... cylinder, 28... rod guide (blocking member), 45... piston, 48... first chamber, 49... second chamber, 51, 51B... piston rod, 59, 60... damping force generating mechanism, 81, 81C, 81D... stopper member, 81Daa, 82da... end surface (abutment surface), 82, 82A, 82B, 82C... washers, 82a, 82Aa, 82Ba, 82Ca...outer peripheral surface, 82b, 82Ab, 82Bb, 82Cb...inner peripheral surface, 83...elastic member, 101, 101A, 101C...longitudinal groove, 102, 171...horizontal groove, 102A...horizontal hole, 122...passage (first passage), 123, 123A to 123C...passage (second passage), 124, 124A to 124D...passage (third passage), 151...communicating groove, 161...longitudinal groove, L...oil (working fluid).

Claims

1. A shock absorber comprising: a cylinder in which a working fluid is sealed; a piston slidably fitted within the cylinder to divide the inside of the cylinder into two chambers; a rod guide closing the cylinder; a piston rod inserted through the rod guide, with a first end connected to the piston and a second end extending to the outside of the cylinder; a stopper member provided on the piston rod; an elastic member provided between the stopper member and the rod guide, formed to allow the working fluid to flow between its radial outer periphery and the cylinder, the elastic member moving together with the piston rod and being deformable; a washer provided between the stopper member and the elastic member; a first passage through which the working fluid can flow is formed between the radial outer periphery of the washer and the cylinder; a second passage through which the working fluid can flow is formed between the radial inner periphery of the washer and the piston rod; and a third passage communicating with the second passage is provided in the washer or the stopper member.

2. A shock absorber as set forth in claim 1, wherein said third passage is formed in the contact surface between said washer and said stopper member.

3. A shock absorber as claimed in claim 2, wherein said third passage is formed in said washer and is formed in phase with said second passage.

4. A shock absorber as claimed in claim 1, wherein said third passage is formed by a horizontal hole between both axial ends of said washer.

5. A shock absorber as claimed in any one of claims 1 to 4, wherein the flow passage areas of the second passage and the third passage are formed to be larger than the flow passage area between the elastic member and the cylinder.

6. A shock absorber as claimed in any one of claims 1 to 4, wherein the flow area of ​​the second passage and the third passage is formed to be larger than the flow area of ​​a passage through a damping force generating mechanism provided in the piston.

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