Buffer

Abstract

To provide a buffer which enables downsizing.SOLUTION: A buffer has: a piston 71 which is provided so as to be slidable into a cylinder 17 and partitions the inside of the cylinder 17 into a first chamber 72 and a second chamber 73; a piston rod 81 which is connected to the piston 71 and extends to the outside of the cylinder 17; a blocking member 65 which is provided at the end of the cylinder 17 to block the cylinder 17; a washer 113 which is inserted into to the cylinder 17; and a stopper member 111 which is supported by a piston rod 81 and may contact with the washer 113. The cylinder 17 has: a slide part 21 in which the piston 71 may slide; and a diameter expansion part 22 having a diameter expanding relative to the slide part 21. The washer 113 is provided at the diameter expansion part 22 so as to be movable in an axial direction and provided with a washer passage 164 in which working fluid L may circulate to at least a radial inner periphery and an axial end.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Some shock absorbers have a stopper fixed to a piston rod, a foam cushion fitted to the underside of a rod guide with a gap between it and the piston rod, and a backup ring loosely fitted into a pressure cylinder with an oil passage between the piston rod and the backup ring that communicates with the gap between the piston rod and the foam cushion and communicates with an upper pressure chamber. As this shock absorber extends, the stopper fixed to the piston rod compresses the foam cushion via the backup ring (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Jpn. Jpn. Published No. 48-4465 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for miniaturization of shock absorbers in terms of installation space and the like.

[0005] Therefore, an object of the present invention is to provide a shock absorber that can be made compact. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, one aspect of the present invention is configured to include a cylinder in which a working fluid is sealed, a piston slidably arranged within the cylinder and dividing the interior of the cylinder into a first chamber and a second chamber, a piston rod connected to the piston and extending outside the cylinder, a closing member arranged at an end of the cylinder and closing the cylinder, a washer inserted into the cylinder, and a stopper member supported by the piston rod and capable of abutting against the washer, wherein the cylinder has a sliding portion against which the piston can slide and an enlarged diameter portion whose diameter is larger than that of the sliding portion, the washer is arranged on the enlarged diameter portion so as to be freely movable axially, and a washer flow path through which the working fluid can flow is formed at least at the radial inner circumference and the axial end. Effect of the Invention

[0007] According to the present invention, miniaturization is possible. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view of a main part of a shock absorber according to a first embodiment of the present invention, showing a state in which a piston is in a predetermined normal use range. [Diagram 3] 1 is a cross-sectional view of a main portion of a shock absorber according to a first embodiment of the present invention, showing a state in which a piston is in a predetermined full extension region. [Figure 4] FIG. 11 is a cross-sectional view of a main part of a shock absorber according to a second embodiment of the present invention, showing a state in which the piston is in a predetermined full extension region. [Diagram 5] FIG. 11 is a cross-sectional view of a main part of a shock absorber according to a second embodiment of the present invention, showing a state in which the piston is in a predetermined fully extended end region. [Figure 6] FIG. 11 is a cross-sectional view of a main part of a shock absorber according to a third embodiment of the present invention, showing a state in which the piston is in a predetermined normal use range. [Figure 7]FIG. 11 is a cross-sectional view of a main part of a shock absorber according to a third embodiment of the present invention, showing a state in which the piston is in a predetermined full extension region. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] The first embodiment will be described with reference to FIGS. FIG. 1 shows a shock absorber 11 according to a first embodiment. The shock absorber 11 is used in a suspension device for a vehicle such as an automobile or a railroad car. Specifically, the shock absorber 11 is used in a suspension device for an automobile. The shock absorber 11 is a double-cylinder shock absorber equipped with a cylinder 17 having an inner cylinder 15 and an outer cylinder 16.

[0010] The inner tube 15 has a cylindrical sliding portion 21, a cylindrical expanded diameter portion 22 whose inner diameter is larger than the inner diameter of the sliding portion 21 and whose outer diameter is larger than the outer diameter of the sliding portion 21, and a tapered connecting portion 23 provided between the sliding portion 21 and the expanded diameter portion 22 to connect them.

[0011] The expanded diameter portion 22 is provided at one axial end of the inner cylinder 15. The expanded diameter portion 22 has a cylindrical inner circumferential surface 25 and a cylindrical outer circumferential surface 26 coaxial with the inner circumferential surface 25.

[0012] The sliding portion 21 extends from the other axial end of the inner cylinder 15 to a middle position on the one end side. The sliding portion 21 has a cylindrical inner circumferential surface 27 and a cylindrical outer circumferential surface 28 coaxial with the inner circumferential surface 27. The sliding portion 21 has an inner circumferential surface 27 with a smaller diameter than an inner circumferential surface 25 of the enlarged diameter portion 22, and an outer circumferential surface 28 with a smaller diameter than an outer circumferential surface 26 of the enlarged diameter portion 22. The enlarged diameter portion 22 has a larger diameter than the sliding portion 21.

[0013] The connecting portion 23 is tapered, with a small diameter on the sliding portion 21 side and a large diameter on the enlarged diameter portion 22 side. The connecting portion 23 is provided on the enlarged diameter portion 22 side of the center of the inner cylinder 15 in the axial direction.

[0014] The inner cylinder 15 is arranged coaxially with the central axis of the sliding portion 21, the expanded diameter portion 22, and the connecting portion 23. The inner cylinder 15 is a stepped cylindrical shape with one end in the axial direction expanded in diameter.

[0015] The outer cylinder 16 is a bottomed cylinder having a larger diameter than the expanded diameter portion 22, which has the largest outer diameter of the inner cylinder 15. The outer cylinder 16 is provided radially outward of the inner cylinder 15 and coaxially with the inner cylinder 15. A reservoir chamber 18 is formed between the outer cylinder 16 and the inner cylinder 15.

[0016] The outer cylinder 16 has a body portion 31 and a bottom portion 32 . The body portion 31 has a cylindrical main body portion 33 and a cylindrical large inner diameter portion 34 whose outer diameter is the same as the outer diameter of the main body portion 33 and whose inner diameter is larger than the inner diameter of the main body portion 33.

[0017] The large inner diameter portion 34 is provided at one axial end of the body portion 31. The main body portion 33 extends from the other axial end of the body portion 31 to a middle position on the one end side. In the body portion 31, the main body portion 33 and the large inner diameter portion 34 are arranged coaxially with their central axes aligned.

[0018] The bottom 32 closes the end of the main body 33 of the body 31 opposite the large inner diameter portion 34 in the axial direction. The end of the large inner diameter portion 34 opposite the main body 33 in the axial direction forms an opening 35.

[0019] The inner cylinder 15 is disposed inside the body portion 31 with the expanded diameter portion 22 oriented so as to be disposed on the opposite side to the bottom portion 32 .

[0020] The shock absorber 11 includes a valve body 41 and a rod guide 42 . The valve body 41 is annular, and is provided at one axial end of the inner cylinder 15 and the outer cylinder 16. The valve body 41 constitutes the base valve 45, and has a stepped outer periphery. The valve body 41 is placed on the bottom 32 of the outer cylinder 16. At that time, the valve body 41 is positioned radially relative to the outer cylinder 16 at the large diameter portion of the outer periphery.

[0021] The rod guide 42 is annular, and is provided at the other axial end of the inner cylinder 15 and the outer cylinder 16. The rod guide 42 is provided on the opening 35 side at one axial end of the cylinder 17. The rod guide 42 has a rod guide body 47 and a collar 48.

[0022] The rod guide body 47 is made of metal and has a circular ring shape. The rod guide body 47 has a large outer diameter portion 51 and a small outer diameter portion 52 on its outer periphery. The outer diameter of the large outer diameter portion 51 is larger than the outer diameter of the small outer diameter portion 52. Therefore, the rod guide body 47 has a stepped outer periphery.

[0023] The collar 48 is cylindrical. The collar 48 is made of a metal cylinder whose inner circumferential surface is coated with a material having high slidability. The collar 48 is fitted and fixed to the inner circumferential portion of the rod guide body 47.

[0024] The rod guide 42 fits into the opening 35 of the large inner diameter portion 34 of the trunk 31 of the outer cylinder 16 at the large outer diameter portion 51 of the rod guide main body 47. The rod guide 42 has an end face 53 at the end opposite to the large outer diameter portion 51 in the axial direction, which is flat and extends perpendicular to the central axis of the rod guide 42. The end face 53 is formed on the rod guide main body 47 and the collar 48.

[0025] The inner cylinder 15 has an end portion opposite to the enlarged diameter portion 22 of the sliding portion 21 in the axial direction, which is fitted into the small diameter portion of the outer periphery of the valve body 41. The inner cylinder 15 has an end portion opposite to the enlarged diameter portion 22 of the sliding portion 21 in the axial direction, which is placed on the bottom portion 32 of the outer cylinder 16 via the valve body 41. The enlarged diameter portion 22 of the inner cylinder 15 is fitted into the small diameter outer diameter portion 52 of the rod guide main body 47. The other end of the inner cylinder 15 is fitted into the body portion 31 of the outer cylinder 16 via the rod guide 42. In this state, the inner cylinder 15 is positioned in the axial direction and the radial direction with respect to the outer cylinder 16. Here, the inner cylinder 15 and the outer cylinder 16 communicate with each other through a passage groove 56 formed in the valve body 41 between the valve body 41 and the bottom portion 32. The area between the valve body 41 and the bottom portion 32 constitutes a reservoir chamber 18, similar to the area between the inner cylinder 15 and the outer cylinder 16.

[0026] The shock absorber 11 is provided with an annular rod seal 61. The rod seal 61 is provided on the opposite side of the bottom 32 of the rod guide 42 in the axial direction of the cylinder 17. This rod seal 61 is also fitted to the large inner diameter portion 34 of the body 31 in the same manner as the rod guide 42. In the outer cylinder 16, a locking portion 63 is formed at the end of the large inner diameter portion 34 of the body 31 opposite the bottom 32 in the axial direction. The locking portion 63 is formed by plastically deforming the large inner diameter portion 34 of the body 31 inward in the radial direction by crimping processing such as curling. The rod seal 61 is sandwiched between the locking portion 63 and the rod guide 42. At that time, the rod seal 61 is pressed against the inner peripheral surface of the large inner diameter portion 34 of the body 31 by the rod guide 42. As a result, the rod seal 61 closes the opening 35 of the outer cylinder 16. Specifically, the rod seal 61 is an oil seal.

[0027] The rod guide 42 and the rod seal 61 are provided at the axial end of the cylinder 17 and constitute a blocking member 65 that blocks the cylinder 17.

[0028] The shock absorber 11 includes a piston 71. The piston 71 is slidably provided in the sliding portion 21 of the inner tube 15 of the cylinder 17. The piston 71 divides the inner tube 15 into a first chamber 72 and a second chamber 73. The first chamber 72 is provided between the piston 71 and the rod guide 42 in the inner tube 15. The second chamber 73 is provided between the piston 71 and the valve body 41 in the inner tube 15. The second chamber 73 is divided from the reservoir chamber 18 by the valve body 41. In the cylinder 17, the first chamber 72 and the second chamber 73 are filled with oil L as a working fluid. In the cylinder 17, the reservoir chamber 18 is filled with gas G and oil L as a working fluid.

[0029] The shock absorber 11 is equipped with a piston rod 81. One axial end portion of the piston rod 81 is inserted inside the cylinder 17. The one end portion of the piston rod 81 is connected to the piston 71. An axial intermediate portion of the piston rod 81 is inserted through a rod guide 42 and a rod seal 61. The other axial end portion of the piston rod 81 extends outside the cylinder 17.

[0030] The piston rod 81 is made of metal and passes through the first chamber 72. The piston rod 81 does not pass through the second chamber 73. Therefore, the first chamber 72 is a rod side chamber through which the piston rod 81 passes. The second chamber 73 is a bottom side chamber on the bottom 32 side of the cylinder 17.

[0031] In the shock absorber 11, the body 31 of the outer cylinder 16 is connected to the wheel side of the vehicle, and the part of the piston rod 81 that extends outward from the cylinder 17 is connected to the body side of the vehicle. If the shock absorber 11 is a single-cylinder type, it is also possible to connect the cylinder 17 to the wheel side of the vehicle, and connect the part of the piston rod 81 that extends outward from the cylinder 17 to the body side of the vehicle.

[0032] The piston rod 81 has a main shaft portion 82 and a mounting shaft portion 83 . The mounting shaft portion 83 has an outer diameter smaller than that of the main shaft portion 82. The mounting shaft portion 83 side of the piston rod 81 is inserted into the cylinder 17, and the piston 71 is attached to the mounting shaft portion 83 by a nut member 84.

[0033] The outer circumferential surface 86 of the main shaft portion 82 is cylindrical. The main shaft portion 82 of the piston rod 81 passes through the rod guide 42 and the rod seal 61. An engagement groove 85 is formed in the main shaft portion 82 of the piston rod 81. The engagement groove 85 is recessed radially inward from the outer circumferential surface 86 of the main shaft portion 82. The engagement groove 85 is annular and coaxial with the outer circumferential surface 86 of the main shaft portion 82. The engagement groove 85 is formed in a portion of the main shaft portion 82 that is disposed within the inner cylinder 15 and is disposed between the piston 71 and the rod guide 42.

[0034] The rod guide 42 and the rod seal 61 are provided on the portion of the cylinder 17 on the side from which the piston rod 81 extends. The rod guide 42 slidably supports the piston rod 81. The piston rod 81 is guided by the rod guide 42 at the outer circumferential surface 86 of the main shaft portion 82. The end surface 53 of the rod guide 42 extends perpendicular to the central axis of the piston rod 81. The piston rod 81 moves axially together with the piston 71 relative to the cylinder 17. During the extension stroke of the shock absorber 11, in which the piston rod 81 increases the amount of protrusion from the cylinder 17, the piston 71 moves toward the first chamber 72. During the compression stroke of the shock absorber 11, in which the piston rod 81 decreases the amount of protrusion from the cylinder 17, the piston 71 moves toward the second chamber 73.

[0035] The rod seal 61 is provided on the side where the piston rod 81 of the cylinder 17 extends, i.e., on the opening 35 side of the outer cylinder 16. The rod seal 61, together with the rod guide 42, seals between the body 31 of the outer cylinder 16 and the main shaft portion 82 of the piston rod 81, and prevents the oil liquid L in the inner cylinder 15 and the gas G and oil liquid L in the reservoir chamber 18 from leaking to the outside.

[0036] A passage 91 and a passage 92 are formed in the piston 71. Both the passage 91 and the passage 92 axially pass through the piston 71. The passages 91, 92 can communicate between the first chamber 72 and the second chamber 73. The shock absorber 11 includes a disc valve 95 and a disc valve 96.

[0037] The disk valve 95 is provided on the opposite side of the piston 71 from the bottom portion 32 in the axial direction. The disk valve 95 has an annular shape, and closes the passage 91 by abutting against the piston 71.

[0038] The disk valve 96 is provided on the bottom portion 32 side in the axial direction of the piston 71. The disk valve 96 has an annular shape, and closes the passage 92 by abutting against the piston 71.

[0039] The disc valves 95 and 96 are attached to the piston rod 81 together with the piston 71 by a nut member 84 .

[0040] When the piston rod 81 moves to the compression side increasing the amount of penetration into the inner cylinder 15 and the outer cylinder 16 and the piston 71 moves in a direction narrowing the second chamber 73, the pressure in the second chamber 73 becomes higher than the pressure in the first chamber 72. Then, the disc valve 95 opens the passage 91 to allow the oil L in the second chamber 73 to flow through the passage 91 to the first chamber 72. At that time, the disc valve 95 generates a damping force.

[0041] When the piston rod 81 moves to the extension side, increasing the amount of protrusion from the inner cylinder 15 and the outer cylinder 16, and the piston 71 moves in a direction narrowing the first chamber 72, the pressure in the first chamber 72 becomes higher than the pressure in the second chamber 73. Then, the disc valve 96 opens the passage 92, allowing the oil L in the first chamber 72 to flow through the passage 92 to the second chamber 73. At that time, the disc valve 96 generates a damping force.

[0042] A fixed orifice (not shown) is formed in at least one of the piston 71 and the disc valve 95. This fixed orifice allows communication between the first chamber 72 and the second chamber 73 via the passage 91 even when the disc valve 95 is in a state where the passage 91 is most blocked.

[0043] A fixed orifice (not shown) is formed in at least one of the piston 71 and the disc valve 96. This fixed orifice allows communication between the first chamber 72 and the second chamber 73 via the passage 92 even when the disc valve 96 is in a state where the passage 92 is most blocked.

[0044] A passage 101 and a passage 102 are formed in the valve body 41. Both the passage 101 and the passage 102 axially penetrate the valve body 41. Both the passages 101 and 102 can communicate between the second chamber 73 and the reservoir chamber 18.

[0045] The base valve 45 includes a disc valve 105 and a disc valve 106 . The disk valve 105 is provided on the bottom 32 side in the axial direction of the valve body 41. The disk valve 105 closes the passage 101 by abutting against the valve body 41.

[0046] The disk valve 106 is provided on the opposite side of the valve body 41 in the axial direction to the bottom portion 32. The disk valve 106 closes the passage 102 by abutting against the valve body 41.

[0047] The base valve 45 has a pin 68. The pin 68 attaches the disk valves 105, 66 to the valve body 41. The valve body 41, the disc valves 105 and 66, the pin 68, etc. constitute the base valve 45.

[0048] When the piston rod 81 moves toward the compression side and the piston 71 moves in a direction narrowing the second chamber 73, the pressure in the second chamber 73 becomes higher than the pressure in the reservoir chamber 18. Then, in the base valve 45, the disc valve 105 opens the passage 101, allowing the oil L in the second chamber 73 to flow into the reservoir chamber 18. At that time, the disc valve 105 generates a damping force.

[0049] When the piston rod 81 moves to the extension side and the piston 71 moves toward the first chamber 72, the pressure in the second chamber 73 drops below the pressure in the reservoir chamber 18. Then, in the base valve 45, the disc valve 106 opens the passage 102, allowing the oil L in the reservoir chamber 18 to flow into the second chamber 73. The disc valve 106 is a suction valve that allows the oil L to flow from the reservoir chamber 18 into the second chamber 73 without generating any substantial damping force.

[0050] 2, the shock absorber 11 includes a stopper member 111, a first cushion member 112, and a washer 113. The stopper member 111, the first cushion member 112, and the washer 113 are all provided in the first chamber 72.

[0051] The stopper member 111 has a fixed member 121 and a second cushion member 122 .

[0052] The fixing member 121 is made of metal and has a circular ring shape. The fixing member 121 has a support portion 125 and a fixing portion 126.

[0053] The support portion 125 is in the form of a circular plate with a hole. The support portion 125 has a support surface 127 on one side in the axial direction thereof, which is in the form of a plane extending perpendicular to the central axis of the support portion 125.

[0054] The fixing portion 126 protrudes from the inner peripheral edge of the support portion 125 on the opposite side to the support surface 127 in the axial direction of the support portion 125. The fixing portion 126 is cylindrical. The outer diameter of the fixing portion 126 is smaller than the outer diameter of the support portion 125.

[0055] Before the fixing member 121 is attached to the piston rod 81, the fixing portion 126 has a cylindrical shape. In this state, the fixing member 121 is fitted to the main shaft portion 82 of the piston rod 81 in a direction in which the fixing portion 126 protrudes from the support portion 125 toward the attachment shaft portion 83. Then, the fixing portion 126 is crimped radially inward with its position aligned with the engagement groove 85 of the piston rod 81. As a result, the fixing portion 126 is plastically deformed and enters the engagement groove 85, and the fixing member 121 is fixed to the piston rod 81. In this state, the support surface 127 of the support portion 125 has a planar shape extending perpendicularly to the central axis of the piston rod 81. The fixing member 121 is provided to the piston rod 81 with the main shaft portion 82 of the piston rod 81 inserted inside in this manner.

[0056] The rod guide 42 is disposed on the axial side of the fixed member 121 opposite to the piston 71. The outer diameter of the support portion 125 of the fixed member 121 attached to the piston rod 81 is smaller than the inner diameter of the sliding portion 21 of the inner cylinder 15. Thus, the support portion 125 of the fixed member 121 has a radial gap with the inner circumferential surface 27 of the sliding portion 21 of the inner cylinder 15.

[0057] The second cushion member 122 is an elastic body made of an elastic material such as rubber. The second cushion member 122 is cylindrical. The second cushion member 122 has a cylindrical inner circumferential surface 131, a cylindrical outer circumferential surface 132, a flat first end surface 133 on one axial side, and a flat second end surface 134 on the other axial side.

[0058] The inner peripheral surface 131 and the outer peripheral surface 132 are formed coaxially, and the first end surface 133 and the second end surface 134 extend perpendicular to the central axis of the inner peripheral surface 131 and the outer peripheral surface 132 .

[0059] The second cushion member 122 is fitted between the fixed member 121 and the rod guide 42 of the main shaft portion 82 of the piston rod 81. At this time, the inner peripheral surface 131 of the second cushion member 122 is fitted to the outer peripheral surface 86 of the main shaft portion 82 of the piston rod 81, and the first end surface 133 abuts against the support surface 127 of the support portion 125 of the fixed member 121. In this manner, the second cushion member 122 is supported by the main shaft portion 82 of the piston rod 81 via the fixed member 121. The second cushion member 122 is elastically deformable in the axial direction while maintaining the state in which the first end surface 133 abuts against the support surface 127 of the fixed member 121. The outer diameter of the second cushion member 122, i.e., the diameter of the outer peripheral surface 132, is smaller than the inner diameter of the sliding portion 21 of the inner cylinder 15 and smaller than the outer diameter of the support portion 125 of the fixed member 121.

[0060] The washer 113 is made of metal or synthetic resin, and has higher rigidity than the second cushion member 122. The washer 113 is annular. The washer 113 has a cylindrical inner circumferential surface 141, a cylindrical outer circumferential surface 142, a flat first end face 143 on one axial side, a flat second end face 144 on the other axial side, an axial groove 145, and a radial groove 146.

[0061] The inner peripheral surface 141 and the outer peripheral surface 142 are formed coaxially, and the first end surface 143 and the second end surface 144 are planar and extend perpendicular to the central axis of the inner peripheral surface 141 and the outer peripheral surface 142 .

[0062] The axial groove 145 is recessed from the inner circumferential surface 141 outward in the radial direction of the inner circumferential surface 141. The axial groove 145 penetrates the washer 113 in the axial direction of the washer 113. A plurality of the axial grooves 145 are provided in the washer 113. The multiple axial grooves 145 are arranged at equal intervals in the circumferential direction of the washer 113.

[0063] The radial groove 146 is recessed from the first end face 143 toward the second end face 144 in the axial direction of the washer 113. The radial groove 146 extends from the end of the axial groove 145 on the first end face 143 side to a predetermined intermediate position on the outer circumferential surface 142 side along the radial direction of the washer 113. The radial grooves 146 are formed in the washer 113 in one-to-one correspondence with the multiple axial grooves 145. Thus, multiple radial grooves 156 are formed in the washer 113 radially at equal intervals in the circumferential direction of the washer 113.

[0064] The washer 113 has an outer diameter, i.e., the diameter of an outer peripheral surface 142, which is larger than the inner diameter, i.e., the diameter of the inner peripheral surface 27, of the sliding portion 21 of the inner cylinder 15, and is slightly smaller than the inner diameter, i.e., the diameter of the inner peripheral surface 25, of the expanded diameter portion 22 of the inner cylinder 15. The washer 113 has an inner diameter, i.e., the diameter of the inner peripheral surface 141, which is slightly larger than the diameter of the outer peripheral surface 86 of the main shaft portion 82 of the piston rod 81.

[0065] The washer 113 is disposed inside the enlarged diameter portion 22, and is disposed between the second cushion member 122 of the main shaft portion 82 of the piston rod 81 and the rod guide 42 with the radial groove 146 facing the connecting portion 23. At this time, the inner peripheral surface 141 of the washer 113 has a slight radial gap between the outer peripheral surface 86 of the main shaft portion 82 of the piston rod 81. Also, at this time, the outer peripheral surface 142 of the washer 113 has a slight radial gap between the inner peripheral surface 25 of the enlarged diameter portion 22 of the inner tube 15. Therefore, the washer 113 is axially slidable relative to the enlarged diameter portion 22 of the inner tube 15, and is also axially slidable relative to the main shaft portion 82 of the piston rod 81. That is, the washer 113 moves in the axial direction while being guided by the enlarged diameter portion 22 of the inner cylinder 15 and the main shaft portion 82 of the piston rod 81 in a state where the washer 113 is positioned in the radial direction by the enlarged diameter portion 22 of the inner cylinder 15 and the main shaft portion 82 of the piston rod 81. In other words, the washer 113 is provided so as to be freely movable in the axial direction relative to the enlarged diameter portion 22 of the inner cylinder 15 and the main shaft portion 82 of the piston rod 81.

[0066] Here, the radial outer end position of the radial groove 146 of the washer 113 when supported by the enlarged diameter portion 22 of the inner tube 15 and the main shaft portion 82 of the piston rod 81 is located outside the radial outer end position of the second end face 134 of the second cushion member 122 when supported by the piston rod 81.

[0067] The first cushion member 112 is an elastic body made of an elastic material such as rubber and has an annular shape. The first cushion member 112 has a cylindrical inner circumferential surface 151, a cylindrical outer circumferential surface 152, a flat first end face 153 on one axial side, a flat second end face 154 on the other axial side, an axial groove 155, and a radial groove 156.

[0068] The inner peripheral surface 151 and the outer peripheral surface 152 are formed coaxially, and the first end surface 153 and the second end surface 154 are planar and extend perpendicular to the central axis of the inner peripheral surface 151 and the outer peripheral surface 152 .

[0069] The axial groove 155 is recessed from the inner circumferential surface 151 outward in the radial direction of the inner circumferential surface 151. The axial groove 155 penetrates the first cushion member 112 in the axial direction of the first cushion member 112. A plurality of axial grooves 155 are provided in the first cushion member 112. The multiple axial grooves 155 are arranged at equal intervals in the circumferential direction of the first cushion member 112.

[0070] The radial grooves 156 are recessed from the first end face 153 toward the second end face 154 in the axial direction of the first cushion member 112. The radial grooves 156 extend from the end of the axial groove 155 on the first end face 153 side to the outer circumferential surface 152 along the radial direction of the first cushion member 112. The first cushion member 112 is formed with radial grooves 156 in one-to-one correspondence with each of the multiple axial grooves 155. Thus, the first cushion member 112 is formed with multiple radial grooves 156 at equal intervals in the circumferential direction of the first cushion member 112.

[0071] The outer diameter of the first cushion member 112, i.e., the diameter of the outer peripheral surface 152, is smaller than the outer diameter of the washer 113, i.e., the diameter of the outer peripheral surface 142. The inner diameter of the first cushion member 112, i.e., the diameter of the inner peripheral surface 151, is slightly larger than the diameter of the outer peripheral surface 86 of the main shaft portion 82 of the piston rod 81.

[0072] The first cushion member 112 is disposed inside the enlarged diameter portion 22 of the inner cylinder 15, and is fitted between the washer 113 of the main shaft portion 82 of the piston rod 81 and the rod guide 42 with the radial groove 156 facing the washer 113 side. At this time, the inner circumferential surface 151 of the first cushion member 112 has a slight radial gap between itself and the outer circumferential surface 86 of the main shaft portion 82 of the piston rod 81, and the outer circumferential surface 152 has a radial gap between itself and the inner circumferential surface 25 of the enlarged diameter portion 22 of the inner cylinder 15. Therefore, the first cushion member 112 is axially slidable relative to the main shaft portion 82 of the piston rod 81, and is axially movable relative to the enlarged diameter portion 22 of the inner cylinder 15. That is, the first cushion member 112 is positioned in the radial direction by the main shaft portion 82 of the piston rod 81, and moves in the axial direction while being guided by the main shaft portion 82 of the piston rod 81 in a state in which there is an annular gap with respect to the expanded diameter portion 22 of the inner cylinder 15. The first cushion member 112 is disposed between the washer 113 and the rod guide 42, and is freely movable in the axial direction.

[0073] The outer end position of the radial groove 146 in the radial direction of the first cushion member 112 in a state supported by the piston rod 81 is located inside the outer diameter position of the washer 113 in a state supported by the piston rod 81.

[0074] The first cushion member 112 can abut against the second end face 144 of the washer 113 at the first end face 153. In a state in which the first end face 153 of the first cushion member 112 and the second end face 144 of the washer 113 are in abutment with each other, a first flow path 161 is formed between the plurality of radial grooves 156 of the first cushion member 112 and the second end face 144 of the washer 113, the first flow path 161 extending in the radial direction of the first cushion member 112 from a portion between the inner circumferential surface 25 of the expanded diameter portion 22 of the inner cylinder 15 of the first chamber 72 and the outer circumferential surface 152 of the first cushion member 112 and crossing the first cushion member 112 in the radial direction. The first flow path 161 allows the oil liquid L to flow.

[0075] In this state, a second flow passage 162 is formed between the inner circumferential surface 151 and the multiple axial grooves 155 of the first cushion member 112 and the outer circumferential surface 86 of the main shaft portion 82 of the piston rod 81, the second flow passage 162 extending in the axial direction of the first cushion member 112 and cutting through the first cushion member 112 in the axial direction. In this state, the first flow passage 161 communicates with the second flow passage 162. The first flow passage 161 and the second flow passage 162 communicate with a portion of the first chamber 72 between the rod guide 42 and the washer 113. The second flow passage 162 allows the oil liquid L to flow.

[0076] Therefore, the first cushion member 112 is formed with a first flow passage 161 provided at the axial end on the washer 113 side, and a second flow passage 162 provided on the radially inner periphery.

[0077] In this state, a washer passage 164 extends in the axial direction of the washer 113 and cuts through the washer 113 in the axial direction between the inner circumferential surface 141 and the plurality of axial grooves 145 of the washer 113 and the outer circumferential surface 86 of the main shaft portion 82 of the piston rod 81. In this state, the washer passage 164 has an annular shape and cuts through the washer 113 in the axial direction. In this state, the first passage 161 and the second passage 162 communicate with the washer passage 164. In this state, the washer passage 164 communicates with a portion of the first chamber 72 between the washer 113 and the piston 71. The washer passage 164 allows the oil L to flow through it. In addition, in order to stabilize the communication between the first flow path 161 and the second flow path 162 and the washer flow path 164, a circular notch is provided in at least one of the corners of the boundary between the inner surface 141 and the second end face 144 of the washer 113 and the corners of the boundary between the inner surface 151 and the first end face 153 of the first cushion member 112.

[0078] The second cushion member 122 can abut against the first end face 143 of the washer 113 at its second end face 134. As shown in FIG. 3, when the second end face 134 of the second cushion member 122 and the first end face 143 of the washer 113 are in abutment with each other, the washer passage 164 is formed between the inner peripheral surface 141 of the washer 113 and the multiple axial grooves 145 and the outer peripheral surface 86 of the main shaft portion 82 of the piston rod 81, and between the multiple radial grooves 146 of the washer 113 and the second end face 134 of the second cushion member 122. Therefore, in this state, the washer passage 164 extends in the axial direction of the washer 113, crosses the washer 113 in the axial direction, and then extends radially outward of the washer 113. Even in this state, the first passage 161 and the second passage 162 communicate with the washer passage 164. In this state, the washer passage 164 communicates with the portion of the first chamber 72 between the washer 113 and the piston 71. Thus, the washer 113 is inserted into the cylinder 17, and the washer passage 164 through which the oil L, which is the working fluid, can flow is formed at least between the radial inner periphery and the axial end.

[0079] The flow path area of ​​the washer flow path 164 is narrower in a state where the first end surface 143 of the washer 113 and the second end surface 134 of the second cushion member 122 are in contact with each other (hereinafter referred to as a throttled state) than in a state where the first end surface 143 of the washer 113 and the second end surface 134 of the second cushion member 122 are not in contact with each other (hereinafter referred to as a non-throttled state). In other words, the flow path area of ​​the washer flow path 164 in the throttled state is smaller than the flow path area of ​​the washer flow path 164 in the non-throttled state. The flow path area of ​​the washer flow path 164 in the throttled state is smaller than the combined flow path area of ​​the first flow path 161 and the second flow path 162.

[0080] The first cushion member 112 and the second cushion member 122 are made of, for example, NBR (nitrile rubber).

[0081] In the shock absorber 11 configured as described above, the second cushion member 122 moves together with the fixed member 121 and the piston rod 81 with the first end face 133 in contact with the support surface 127 of the fixed member 121 as shown in Fig. 2. When the piston rod 81 moves to the extension side, i.e., in the direction extending from the cylinder 17, and is positioned at a first predetermined position on the fully extended side, the second end face 134 of the second cushion member 122 comes into contact with the first end face 143 of the washer 113, causing the washer flow passage 164 to be in a throttled state. Then, the flow passage area of ​​the washer flow passage 164 becomes smaller than the combined flow passage area of ​​the first flow passage 161 and the second flow passage 162, and the washer flow passage 164 becomes throttled.

[0082] 3, when the piston rod 81 moves further in the direction extending from the cylinder 17, the oil L in the portion between the rod guide 42 and the washer 113 in the first chamber 72 flows to the portion between the washer 113 and the piston 71 in the first chamber 72 via the first flow path 161, the second flow path 162, and the washer flow path 164 in a throttled state. At that time, the washer flow path 164 becomes a throttle and becomes a flow path resistance, suppressing the flow of the oil L, and as a result, a damping force is generated against the movement of the piston rod 81 in the extension side. In other words, the stopper member 111, the first cushion member 112, and the washer 113 function as a hydraulic stopper that generates a damping force against the movement of the piston rod 81 in the extension side.

[0083] From this state, when the piston rod 81 moves further in the direction extending from the cylinder 17, the first cushion member 112 comes into contact with the end face 53 of the rod guide 42 at the second end face 154. When the piston rod 81 moves further in the direction extending from the cylinder 17, both the first cushion member 112 and the second cushion member 122 elastically deform in the axial direction, generating an even greater damping force against the movement of the piston rod 81 in the extension side.

[0084] When the first cushion member 112 and the second cushion member 122 are elastically deformed to the limit state, the piston rod 81 is restricted from moving further toward the extension side and stops. In this way, the first cushion member 112 and the second cushion member 122 are elastically deformed when the piston rod 81 is fully extended, and the impact when the piston rod 81 is stopped against the cylinder 17 is mitigated.

[0085] When the piston rod 81 moves from this state toward the contraction side, that is, in the direction of entering the cylinder 17, the second cushion member 122 of the stopper member 111 moves together with the piston rod 81, and the second end surface 134 moves away from the first end surface 143 of the washer 113. As a result, the washer passage 164 changes from a throttled state to a non-throttled state. As a result, the oil L in the portion between the washer 113 and the piston 71 of the first chamber 72 flows smoothly through the washer passage 164 in the non-throttled state, the first passage 161, and the second passage 162 to the portion between the rod guide 42 and the washer 113 of the first chamber 72. Therefore, the first cushion member 112 and the washer 113 move smoothly toward the connecting portion 23 of the inner cylinder 15 by their own weights, and as shown in FIG. 2, the washer 113 comes into contact with the connecting portion 23 and stops, and the first cushion member 112 comes into contact with the washer 113 and stops.

[0086] The above-mentioned Patent Document 1 discloses a shock absorber having a stopper fixed to a piston rod, a foam cushion fitted to the underside of a rod guide with a gap between it and the piston rod, and a backup ring loosely fitted in a pressure cylinder with an oil passage between the piston rod and the backup ring that communicates with the gap between the piston rod and the foam cushion and communicates with an upper pressure chamber. As the shock absorber extends, the stopper fixed to the piston rod compresses the foam cushion via the backup ring, and the flow passage between the stopper and the backup ring is narrowed to suppress the flow of oil, thereby generating a damping force against the movement of the piston rod.

[0087] Meanwhile, there is a demand for miniaturization of shock absorbers in terms of installation space, etc. In order to miniaturize shock absorbers, for example, it is possible to reduce the radial gap between the cylinder and the piston rod. However, if the radial gap between the cylinder and the piston rod is reduced, there is a possibility that the moving speed of the piston rod cannot be sufficiently reduced even if the flow path is narrowed. In other words, if the radial gap between the inner cylinder and the piston rod is reduced, the moving speed of the piston rod becomes faster when the radial gap between the inner cylinder and the piston rod is large, assuming the same throttling flow rate.

[0088] In the shock absorber 11 of the first embodiment, the cylinder 17 has a sliding part 21 on which the piston 71 can slide and an enlarged diameter part 22 whose diameter is larger than that of the sliding part 21, and a washer 113 provided in the enlarged diameter part 22 so as to be movable in the axial direction has a washer passage 164 through which the oil L can flow at least between the radial inner circumference and the axial end. Then, the stopper member 111 supported by the piston rod 81 comes into contact with the washer 113 to narrow the passage of the washer passage 164, thereby generating a damping force against the movement of the piston rod 81. In this way, the shock absorber 11 provides the cylinder 17 with the enlarged diameter part 22 whose diameter is larger than that of the sliding part 21 on which the piston 71 can slide, and provides the washer 113 in the enlarged diameter part 22, so that a radial gap between the cylinder 17 and the piston rod 81 can be secured within the movement range of the washer 113. Therefore, even if the radial gap between the cylinder 17 and the piston rod 81 is made small, the movement speed of the piston rod 81 can be sufficiently reduced by the washer 113 and the stopper member 111.

[0089] In addition, since the shock absorber 11 has the first cushion member 112 provided between the washer 113 and the blocking member 65, the first cushion member 112 provides a bending characteristic and can soften the impact when the piston rod 81 stops, thereby suppressing the generation of hitting noises, etc. Moreover, since the first cushion member 112 is formed with the first flow passage 161 provided at the axial end on the washer 113 side and the second flow passage 162 provided on the radial inner circumference, the oil liquid L can flow satisfactorily in the washer flow passage 164 even when it abuts against the washer 113.

[0090] [Second embodiment] Next, the second embodiment will be described with a focus on differences from the first embodiment, mainly with reference to Figures 4 and 5. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0091] As shown in Fig. 4, in the shock absorber 11A of the second embodiment, a valve-closing portion 181 is provided inside the expanded diameter portion 22 of the inner cylinder 15. The valve-closing portion 181 is cylindrical. The valve-closing portion 181 is made of metal or synthetic resin, and has higher rigidity than the first cushion member 112. The valve-closing portion 181 has a cylindrical inner circumferential surface 191, a cylindrical outer circumferential surface 192, a flat first end face 193 on one axial side, and a flat second end face 194 on the other axial side.

[0092] The inner circumferential surface 191 and the outer circumferential surface 192 are formed coaxially, and the first end surface 193 and the second end surface 194 extend perpendicularly to the central axis of the inner circumferential surface 191 and the outer circumferential surface 192. The inner diameter of the valve-closing portion 181, i.e., the diameter of the inner circumferential surface 191, is slightly larger than the outer diameter of the first cushion member 112, i.e., the diameter of the outer circumferential surface 152. In other words, the valve-closing portion 181 is formed so that the inner circumference has a larger diameter than the outer circumference of the first cushion member 112. The axial length of the valve-closing portion 181 is longer than the axial length of the first cushion member 112.

[0093] The valve-closing portion 181 has its outer circumferential surface 192 fitted and fixed to the inner circumferential surface 25 of the enlarged diameter portion 22 of the inner cylinder 15. At that time, the valve-closing portion 181 abuts against the end face 53 of the rod guide 42 at a second end face 194. Therefore, the valve-closing portion 181 extends parallel to the end face 53 with the first end face 193 located at the end opposite to the end face 53 of the rod guide 42 in the axial direction.

[0094] In shock absorber 11A, washer 113A, which is partially different from washer 113, is provided in place of washer 113. Washer 113A has a shape on the outer circumferential side different from that of washer 113. Washer 113A has a step portion 201 formed on the outer circumferential side of the end portion opposite first end face 143 in the axial direction.

[0095] Washer 113A has a second end face 144A having an inner diameter equal to that of second end face 144 and an outer diameter smaller than that of second end face 144, on the inner circumferential surface 141 side of stepped portion 201 in the radial direction. In addition, washer 113A has an outer circumferential surface 142A having an axial length shorter than that of outer circumferential surface 142, on the first end face 143 side of stepped portion 201 in the axial direction.

[0096] The step portion 201 has a cylindrical axial surface portion 202 extending from the outer peripheral edge of the second end face 144A to the first end face 143 side along the axial direction of the washer 113A, and a flat radial surface portion 203 extending from the end edge of the outer peripheral surface 142A on the second end face 144A side in the axial direction of the washer 113A toward the axial surface portion 202. The axial surface portion 202 is coaxial with the inner peripheral surface 141 and the outer peripheral surface 142A, and the radial surface portion 203 extends in parallel with the first end face 143 and the second end face 144A. The diameter of the axial surface portion 202 is equal to the outer diameter of the first cushion member 112, i.e., the diameter of the outer peripheral surface 152, and is slightly smaller than the inner diameter of the valve-closing portion 181, i.e., the diameter of the inner peripheral surface 191.

[0097] The first cushion member 112 can abut against the second end face 144A of the washer 113A at the first end face 153. When the first end face 153 of the first cushion member 112 and the second end face 144A of the washer 113A are in abutment with each other as shown in Fig. 4, the first flow passage 161 similar to that of the first embodiment is formed between the multiple radial grooves 156 of the first cushion member 112 and the second end face 144A of the washer 113A. Thus, the first cushion member 112 is formed with the first flow passage 161 provided at the axial end on the washer 113A side and the second flow passage 162 provided on the radial inner circumference.

[0098] In this state, the washer passage 164 is formed between the inner circumferential surface 141 and the multiple axial grooves 145 of the washer 113A and the outer circumferential surface 86 of the main shaft portion 82 of the piston rod 81, similar to that of the first embodiment. As shown in FIG. 4, when the second cushion member 122 abuts against the first end surface 143 of the washer 113A at its second end surface 134, the washer passage 164 extends in the axial direction of the washer 113A, crosses the washer 113A in the axial direction, and then extends in the radial direction of the washer 113A. In this state, the washer passage 164 communicates with the portion of the first chamber 72 between the washer 113A and the piston 71. Thus, the washer 113A is inserted into the cylinder 17, and the washer passage 164 through which the oil L, which is the working fluid, can flow is formed at least between the radial inner periphery and the axial end.

[0099] The flow path area of ​​the washer flow path 164 is narrower in a throttled state in which the first end face 143 of the washer 113A and the second end face 134 of the second cushion member 122 are in contact than in a non-throttled state in which the first end face 143 of the washer 113A and the second end face 134 of the second cushion member 122 are not in contact.

[0100] Here, in the second embodiment, the flow path area of ​​the washer flow path 164 in the throttled state is equal to or smaller than the flow path area of ​​the first flow path 161. In other words, the first flow path 161 is formed to have a flow path area equal to or larger than the flow path area of ​​the washer flow path 164 in the throttled state. Also, the flow path area of ​​the second flow path 162 is smaller than the flow path area of ​​the first flow path 161 and smaller than the flow path area of ​​the washer flow path 164 in the throttled state.

[0101] In the shock absorber 11A configured as described above, when the piston rod 81 moves to the extension side, i.e., in the direction extending from the cylinder 17, and is located at a first predetermined position on the fully extended side, the second end face 134 of the second cushion member 122 comes into contact with the first end face 143 of the washer 113A, causing the washer flow passage 164 to be in a throttled state. Then, the flow passage area of ​​the washer flow passage 164 becomes smaller than the combined flow passage area of ​​the first flow passage 161 and the second flow passage 162, and the washer flow passage 164 becomes throttled.

[0102] 4, when the piston rod 81 moves further in the direction extending from the cylinder 17, the oil L in the portion between the rod guide 42 and the washer 113A in the first chamber 72 flows through the first flow path 161, the second flow path 162, and the washer flow path 164 in a throttled state to the portion between the washer 113A in the first chamber 72 and the piston 71. At that time, the washer flow path 164 becomes a throttle and acts as a flow path resistance, suppressing the flow of the oil L, and as a result, a damping force is generated against the movement of the piston rod 81 in the extension side.

[0103] 5, when the piston rod 81 further moves in the direction extending from the cylinder 17, the first cushion member 112 enters the radial inside of the valve-closing portion 181, and the step portion 201 of the washer 113A also enters the radial inside of the valve-closing portion 181. Then, the first flow path 161 is closed.

[0104] From this state, when the piston rod 81 moves further in the direction extending from the cylinder 17, the oil L that was in the portion between the rod guide 42 and the first cushion member 112 in the first chamber 72 flows through the second flow path 162 and the washer flow path 164 to the portion between the washer 113A and the piston 71 in the first chamber 72. At this time, since the flow path area of ​​the second flow path 162 is smaller than the flow path area of ​​the washer flow path 164, the second flow path 162 becomes a throttle with a smaller flow path area than the washer flow path 164 and has a larger flow path resistance than the washer flow path 164, which further restricts the flow of the oil L. As a result, an even greater damping force is generated against the movement of the piston rod 81 toward the extension side.

[0105] From this state, when the piston rod 81 moves further in the direction extending from the cylinder 17, the washer 113 comes into contact with the first end face 193 of the valve-closing portion 181 at the radial surface portion 203 and stops, and when the piston rod 81 moves further in the direction extending from the cylinder 17, the second cushion member 122 elastically deforms in the axial direction, generating an even greater damping force against the movement of the piston rod 81 in the extension side.

[0106] When the second cushion member 122 is elastically deformed to the limit state, the piston rod 81 is restricted from moving further toward the extension side and stops. In this way, the second cushion member 122 is elastically deformed when the piston rod 81 is fully extended, and absorbs the impact when the piston rod 81 is stopped relative to the cylinder 17.

[0107] When the piston rod 81 moves from this state toward the contraction side, i.e., in the direction of entering the cylinder 17, the second cushion member 122 of the stopper member 111 moves together with the piston rod 81, and the second end face 134 moves away from the first end face 143 of the washer 113. As a result, the washer passage 164 changes from a throttled state to an unthrottled state. As a result, the oil L in the portion between the washer 113A and the piston 71 in the first chamber 72 flows smoothly to the portion between the washer 113A and the first cushion member 112 in the first chamber 72 through the unthrottled washer passage 164, and the washer 113A moves smoothly toward the connecting portion 23 of the inner cylinder 15 by its own weight and comes into contact with the connecting portion 23 to stop. Furthermore, the oil liquid L in the portion between the first cushion member 112 and the washer 113 of the first chamber 72 flows through the second flow passage 162 to the portion between the rod guide 42 of the first chamber 72 and the first cushion member 112, and thus moves by its own weight toward the connecting portion 23 of the inner tube 15. Thereafter, when the first cushion member 112 moves toward the connecting portion 23 side from the valve closing portion 181, the oil liquid L in the portion between the first cushion member 112 and the washer 113 of the first chamber 72 flows to the portion between the rod guide 42 of the first chamber 72 and the first cushion member 112 through the radial gap between the expanded diameter portion 22 in addition to the second flow passage 162, and thus the first cushion member 112 moves smoothly by its own weight to the connecting portion 23 side of the inner tube 15 and comes into contact with the washer 113 to stop.

[0108] The shock absorber 11A of the second embodiment can achieve the same effects as the first embodiment.

[0109] In addition, shock absorber 11A is provided in enlarged diameter portion 22 of cylinder 17, has an inner circumference formed to have a larger diameter than the outer circumference of first cushion member 112, and has a valve closing portion 181 that closes first flow path 161 by inserting first cushion member 112. Therefore, washer flow path 164 is narrowed, and then, when shock absorber 11A approaches the maximum length, first cushion member 112 is inserted into the inner circumference of valve closing portion 181 to close first flow path 161 with valve closing portion 181, thereby reducing the flow path area in two stages and increasing the generated damping force in two stages, thereby providing damping force characteristics as a two-stage hydraulic stopper.

[0110] [Third embodiment] Next, the third embodiment will be described with a focus on the differences from the first embodiment, mainly with reference to Figures 6 and 7. Note that the same names and symbols are used for the parts common to the first embodiment.

[0111] 6, in the shock absorber 11B of the third embodiment, a stopper member 111B that is partially different from the stopper member 111 is provided instead of the stopper member 111. In the stopper member 111B, a second cushion member 122B that is partially different from the second cushion member 122 is provided instead of the second cushion member 122.

[0112] The second cushion member 122B has a base 211 having a shape similar to that of the second cushion member 122, having an outer circumferential surface 132 and a second end face 134, and a perforated circular plate-shaped platform 212 provided at the end of the base 211 opposite the second end face 134 in the axial direction.

[0113] The second cushion member 122B has an inner circumferential surface 131B that extends axially beyond the inner circumferential surface 131 due to the formation of the base portion 212, a planar first end face 133B that extends radially outward from the inner circumferential surface 131B from the edge portion of the inner circumferential surface 131B opposite the second end face 134 in the axial direction, a planar intermediate surface 215 that extends radially outward from the outer circumferential surface 132 from the edge portion of the outer circumferential surface 132 opposite the second end face 134 in the axial direction, and a cylindrical outer circumferential end face 216 that connects the outer circumferential edge portion of the first end face 133B and the outer circumferential edge portion of the intermediate surface 215.

[0114] The inner peripheral surface 131B, the outer peripheral surface 132 and the outer peripheral end surface 216 are formed coaxially, and the first end surface 133A, the second end surface 134 and the intermediate surface 215 extend perpendicular to the central axis of the inner peripheral surface 131B, the outer peripheral surface 132 and the outer peripheral end surface 216.

[0115] The second cushion member 122B is fitted between the fixed member 121 and the rod guide 42 of the main shaft portion 82 of the piston rod 81. At this time, the second cushion member 122 is fitted to the outer circumferential surface 86 of the main shaft portion 82 of the piston rod 81 at the inner circumferential surface 131B, and abuts against the support surface 127 of the support portion 125 of the fixed member 121 at the first end surface 133B. The second cushion member 122B is elastically deformable in the axial direction while maintaining the state in which the first end surface 133B abuts against the support surface 127 of the fixed member 121. The outer diameter of the second cushion member 122B, i.e., the diameter of the outer circumferential end surface 216, is smaller than the inner diameter of the sliding portion 21 of the inner cylinder 15 and smaller than the outer diameter of the support portion 125 of the fixed member 121.

[0116] The shock absorber 11B is provided with a washer 113B which is partially different from the washer 113, instead of the washer 113.

[0117] Washer 113B has a cylindrical inner surface 141B, an outer peripheral surface 142 similar to that of washer 113, a planar first end face 143B on one axial side, a planar second end face 144B on the other axial side, an axial groove 145B, and a radial groove 146B.

[0118] The inner peripheral surface 141B and the outer peripheral surface 142 are formed coaxially, and the first end surface 143B and the second end surface 144B are planar and extend perpendicular to the central axis of the inner peripheral surface 141B and the outer peripheral surface 142.

[0119] The axial groove 145B is recessed from the inner circumferential surface 141B outward in the radial direction of the inner circumferential surface 141B. The axial groove 145B penetrates the washer 113B in the axial direction of the washer 113B. A plurality of the axial grooves 145B are provided in the washer 113B. The plurality of axial grooves 145B are arranged at equal intervals in the circumferential direction of the washer 113B.

[0120] The radial groove 146B is recessed from the first end face 143B toward the second end face 144B in the axial direction of the washer 113B. The radial groove 146B extends from the end of the axial groove 145B on the first end face 143B side to a predetermined intermediate position on the outer circumferential surface 142 side along the radial direction of the washer 113B. The washer 113B is formed with radial grooves 146B in one-to-one correspondence with each of the multiple axial grooves 145B. Thus, the washer 113B is formed with multiple radial grooves 146B at equal intervals in the circumferential direction of the washer 113B.

[0121] The inside diameter of the washer 113B, ie, the diameter of the inner circumferential surface 141B, is slightly larger than the outside diameter of the base portion 211 of the second cushion member 122B, ie, the diameter of the outer circumferential surface 132.

[0122] The washer 113B is fitted to the inside of the enlarged diameter portion 22, and is disposed between the fixed member 121 of the main shaft portion 82 of the piston rod 81 and the rod guide 42 with the radial groove 146B facing the connecting portion 23 side. At this time, the inner peripheral surface 141B of the washer 113B has a radial gap between the outer peripheral surface 86 of the main shaft portion 82 of the piston rod 81. Also, at this time, the outer peripheral surface 142 of the washer 113B has a slight radial gap between the inner peripheral surface 25 of the enlarged diameter portion 22 of the inner tube 15. Therefore, the washer 113B is axially slidable relative to the enlarged diameter portion 22 of the inner tube 15, and is axially movable relative to the main shaft portion 82 of the piston rod 81. That is, the washer 113B is positioned in the radial direction by the expanded diameter portion 22 of the inner cylinder 15, and moves in the axial direction while being guided by the expanded diameter portion 22 of the inner cylinder 15 with an annular gap formed with respect to the main shaft portion 82 of the piston rod 81. In other words, the washer 113B is provided in the expanded diameter portion 22 of the inner cylinder 15 so as to be freely movable in the axial direction.

[0123] Here, the outer end position of the radial groove 146B in the radial direction of the washer 113B when supported by the expanded diameter portion 22 of the inner cylinder 15 is located outside the radial outer end of the intermediate surface 215 of the base portion 212 of the second cushion member 122B when supported by the piston rod 81. The axial length of the base portion 211 of the second cushion member 122B, i.e., the distance between the second end face 134 and the intermediate surface 215, is longer than the axial length of the washer 113B, i.e., the distance between the first end face 143B and the second end face 144B.

[0124] The shock absorber 11B is provided with a valve member 221 instead of the first cushion member 112. The valve member 221 is made of metal or synthetic resin, and has a circular plate shape with holes. The valve member 221 has a higher rigidity than the second cushion member 122B.

[0125] The valve member 221 has an inner diameter that is slightly larger than the outer diameter of the main shaft portion 82 of the piston rod 81, i.e., the diameter of the outer peripheral surface 86, and smaller than the inner diameter of the washer 113B, i.e., the diameter of the inner peripheral surface 141B. The valve member 221 has an outer diameter that is smaller than the outer diameter of the washer 113B, i.e., the diameter of the outer peripheral surface 142, and larger than the diameter of the circumscribing circle of the multiple axial grooves 145B of the washer 113B.

[0126] The valve member 221 is disposed inside the enlarged diameter portion 22 of the inner cylinder 15, and is fitted between the washer 113B of the main shaft portion 82 of the piston rod 81 and the rod guide 42. At this time, the inner peripheral surface of the valve member 221 has a slight radial gap between the outer peripheral surface 86 of the main shaft portion 82 of the piston rod 81, and the outer peripheral surface has a radial gap between the inner peripheral surface 25 of the enlarged diameter portion 22 of the inner cylinder 15. Therefore, the valve member 221 is axially slidable relative to the main shaft portion 82 of the piston rod 81, and is axially movable relative to the enlarged diameter portion 22 of the inner cylinder 15. That is, the valve member 221 is positioned radially by the main shaft portion 82 of the piston rod 81, and moves axially while being guided by the main shaft portion 82 of the piston rod 81 with an annular gap between the valve member 22 of the inner cylinder 15. The valve member 221 is disposed between the washer 113B and the rod guide 42 and is movable in the axial direction.

[0127] 6, the valve member 221 can come into contact with the second end face 144B of the washer 113B. When the valve member 221 is axially separated from the second end face 144B of the washer 113B, the valve member 221 opens the washer flow passage 164B between the washer 113B and the main shaft portion 82 of the piston rod 81. When the valve member 221 is in contact with the second end face 144B of the washer 113B, the valve member 221 closes the washer flow passage 164B between the washer 113B and the main shaft portion 82 of the piston rod 81. The washer flow passage 164B is formed in the washer 113B so as to penetrate the washer 113B in the axial direction, and allows the oil L to flow therethrough.

[0128] 7, the base 211 of the second cushion member 122B can enter the washer 113B, and when the base 211 enters the washer 113B, the base 212 can abut against the first end face 143B of the washer 113B at the intermediate surface 215. When the base 211 of the second cushion member 122B enters the washer 113B and the intermediate surface 215 abuts against the first end face 143B of the washer 113B, the washer flow path 164B is formed between the inner circumferential surface 141B and the multiple axial grooves 145B of the washer 113B and the outer circumferential surface 132 of the base 211 of the second cushion member 122B, and between the multiple radial grooves 146B of the washer 113B and the intermediate surface 215 of the base 212 of the second cushion member 122B. Therefore, in this state, the washer passage 164B extends in the axial direction of the washer 113B, crosses the washer 113B in the axial direction, and then extends in the radial direction of the washer 113B. In this state, the washer passage 164B communicates with the portion of the first chamber 72 between the washer 113B and the piston 71. Therefore, the washer 113B is inserted into the cylinder 17, and the washer passage 164B through which the oil L, which is the working fluid, can flow is formed at least between the radial inner periphery and the axial end.

[0129] The washer flow passage 164B is in a throttled state when the first end surface 143B of the washer 113B and the middle surface 215 of the base portion 212 of the second cushion member 122B come into contact with each other.

[0130] In the shock absorber 11B configured as described above, the second cushion member 122B moves together with the fixed member 121 and the piston rod 81 with the first end surface 133B in contact with the support surface 127 of the fixed member 121 as shown in Fig. 6. Then, when the piston rod 81 moves to the extension side, i.e., in the direction extending from the cylinder 17, and is positioned at a first predetermined position on the fully extended side, the base 211 of the second cushion member 122B enters the washer 113B, and then the valve member 221, which had been in contact with the second end surface 144B of the washer 113B and blocking the washer flow passage 164B, is pushed up as shown in Fig. 7 and separated from the second end surface 144B of the washer 113B, and then the intermediate surface 215 of the base portion 212 comes into contact with the first end surface 143B of the washer 113B to narrow the washer flow passage 164B.

[0131] When the piston rod 81 moves further from this state in the direction extending from the cylinder 17, the oil L that was in the portion between the rod guide 42 and the washer 113B in the first chamber 72 flows through the washer flow passage 164B in the throttled state to the portion between the washer 113B and the piston 71 in the first chamber 72. At that time, the washer flow passage 164B becomes a throttle and acts as a flow passage resistance, suppressing the flow of the oil L, and as a result, a damping force is generated against the movement of the piston rod 81 in the extension side. In other words, the stopper member 111, the first cushion member 112B, and the washer 113B function as a hydraulic stopper that generates a damping force against the movement of the piston rod 81 in the extension side.

[0132] From this state, when the piston rod 81 moves further in the direction extending from the cylinder 17, the valve member 221 comes into contact with the end face 53 of the rod guide 42, and when the piston rod 81 moves further in the direction extending from the cylinder 17, the base 211 and the platform 212 of the second cushion member 122B both elastically deform in the axial direction, generating an even greater damping force against the movement of the piston rod 81 in the extension side.

[0133] When the base 211 and the base 212 of the second cushion member 122B are elastically deformed to the limit, the piston rod 81 is restricted from moving further toward the extension side and stops. In this way, the second cushion member 122B elastically deforms when the piston rod 81 is fully extended, and absorbs the impact when the piston rod 81 is stopped against the cylinder 17.

[0134] When the piston rod 81 moves from this state toward the contraction side, i.e., in the direction of entering the cylinder 17, the fixed member 121 and the second cushion member 122B move together with the piston rod 81. At that time, the washer 113B and the valve member 221 are also initially pressed by the base 211, so that the valve member 221 opens and the oil L flows through the washer flow passage 164B, and then, when the pressure from the base 211 is removed, the valve member 221 opens due to the flow of the oil L, so that the valve member 221 moves toward the connecting portion 23 by its own weight, while the oil L flows through the washer flow passage 164B. When the washer 113B abuts against the connecting portion 23 of the inner cylinder 15, the washer 113B stops, and the valve member 221 also abuts against the washer 113B. As a result, the valve member 221 closes the washer flow passage 164B.

[0135] The shock absorber 11B of the third embodiment can achieve the same effects as the first embodiment.

[0136] In addition, since shock absorber 11B is disposed between washer 113B and rod guide 42, is movable in the axial direction, and has valve member 221 capable of closing washer passage 164B by contacting washer 113B, it is possible to suppress movement of washer 113B toward rod guide 42 due to vibration of shock absorber 11B by closing washer passage 164B with valve member 221. That is, by suppressing movement of oil L in the portion between rod guide 42 and washer 113B in first chamber 72 to the portion between washer 113B and piston 71 in first chamber 72, it is possible to suppress movement of washer 113B toward rod guide 42. [Explanation of symbols]

[0137] 11, 11A, 11B... shock absorber, 17... cylinder, 21... sliding portion, 22... expansion portion, 65... blocking member, 71... piston, 72... first chamber, 73... second chamber, 81... piston rod, 111, 111B... stopper member, 112... first cushion member, 113, 113A, 113B... washer, 161... first flow path, 162... second flow path, 164, 164B... washer flow path, 181... valve closing portion, 221... valve member, L... oil (working fluid).

Claims

1. A cylinder in which a working fluid is sealed; a piston slidably disposed within the cylinder and dividing the interior of the cylinder into a first chamber and a second chamber; a piston rod connected to the piston and extending to the outside of the cylinder; a closing member provided at an end of the cylinder and closing the cylinder; a washer inserted into the cylinder; a stopper member supported by the piston rod and capable of contacting the washer; having The cylinder has a sliding portion on which the piston can slide and an enlarged diameter portion that is enlarged in diameter more than the sliding portion, The washer is provided on the expanded diameter portion so as to be freely movable in the axial direction, and a washer flow passage through which the working fluid can flow is formed at least between the radial inner circumference and the axial end of the shock absorber.

2. The shock absorber according to claim 1, a first cushion member disposed between the washer and the blocking member, movable in the axial direction, and having a first flow passage provided at an axial end on the washer side and a second flow passage provided on a radially inner periphery; A shock absorber having a shock absorber.

3. The shock absorber according to claim 2, a valve closing portion that is provided in the expanded diameter portion of the cylinder, the valve closing portion having an inner circumference larger in diameter than an outer circumference of the first cushion member, and that closes the first flow path by inserting the first cushion member; A shock absorber having a shock absorber.

4. The shock absorber according to claim 3, The first flow path is formed to have a flow path area equal to or larger than the washer flow path, The second flow passage has a flow passage area smaller than that of the washer flow passage.

5. The shock absorber according to claim 1, a valve member disposed between the washer and the blocking member, the valve member being movable in an axial direction and capable of closing the washer flow path by contacting the washer; A shock absorber having a shock absorber.

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