buffer

Abstract

This invention provides a shock absorber that allows for a reduction in the number of parts. [Solution] The system has a fixing member 182 that fixes the first damping force generating mechanisms 85, 86 provided in the first passages 132, 152 and the second damping force generating mechanism 140 provided in the second passages 291, 315 to the piston rod 31. The second damping force generating mechanism 140 includes an annular valve seat member 166 arranged in one of the chambers 23 and a first sub-valve 301 provided on one side of the second passages 291, 315 formed in the valve seat member 166. The device also includes a second sub-valve 321 provided on the other side, and a cap member 178 with a communication hole 195 at its bottom. The fixing member 182 includes a stopper portion 501 facing the cap member 178 and having a contact surface that abuts against the cap member 178 and a flow path 512 that communicates with the communication hole 195, and a nut portion 502 fixed to the piston rod 31, with a loosening prevention portion 532 provided at the end of the nut portion 502.

Description

Technical Field

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

Background Art

[0002] There is known a structure of a shock absorber in which a cap member is fixed to a piston rod by an annular member and a nut (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Incidentally, in the field of shock absorbers, there is a demand for reducing the number of components.

[0005] An object of the present invention is to provide a shock absorber that enables reduction in the number of components.

Means for Solving the Problem

[0006] To achieve the above objective, one embodiment of the shock absorber according to the present invention includes a cylinder in which a working fluid is sealed, a piston slidably provided within the cylinder and dividing the inside of the cylinder into two chambers, a piston rod connected to the piston and extending to the outside of the cylinder, a first passage and a second passage through which the working fluid flows from the upstream chamber to the downstream chamber inside the cylinder as the piston moves, a first damping force generating mechanism provided in the first passage formed in the piston and generating damping force, a second damping force generating mechanism provided in the second passage parallel to the first passage and generating damping force, and the first damping force generating The invention provides a fixing member for fixing the damping mechanism and the second damping force generating mechanism to the piston rod, the second damping force generating mechanism comprising an annular valve seat member disposed in one of the chambers, a first sub-valve provided on one side of the second passage formed in the valve seat member and a second sub-valve provided on the other side, and a bottomed cylindrical cap member having an outer cylindrical portion and a bottom portion, with a communication hole provided in the bottom portion, the fixing member comprising a stopper portion facing the cap member and having a contact surface that abuts the cap member and a flow path that communicates with the communication hole, and a nut portion fixed to the piston rod, with a loosening prevention portion provided at the end of the nut portion. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the number of parts. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing a buffer according to a first embodiment of the present invention. [Figure 2] The main parts of the piston rod of the buffer according to the first embodiment of the present invention are shown, with (a) being a front view and (b) being a side view. [Figure 3] This is a partial cross-sectional view showing the first structural member and the second structural member of a buffer according to the first embodiment of the present invention. [Figure 4] This is a partial cross-sectional view showing the main part of the second structural member of the buffer according to the first embodiment of the present invention. [Figure 5] This is a plan view showing the valve seat member of a buffer according to a first embodiment of the present invention. [Figure 6] This is a bottom view showing the valve seat member of a buffer according to a first embodiment of the present invention. [Figure 7] This is a plan view showing a fixing member of a buffer according to a first embodiment of the present invention. [Figure 8] This is a cross-sectional view taken along line VIII-VIII in Figure 7, showing the fixing member of the buffer according to the first embodiment of the present invention. [Figure 9] This is a front view showing a fixing member of a buffer according to the first embodiment of the present invention. [Figure 10] This is a bottom view showing the fixing member of the buffer according to the first embodiment of the present invention. [Figure 11] This is a plan view showing a fixing member of a buffer according to a second embodiment of the present invention. [Figure 12] This is a cross-sectional view taken along line XII-XII in Figure 11, showing a fixing member of a buffer according to a second embodiment of the present invention. [Figure 13] This is a front view showing a fixing member of a buffer according to a second embodiment of the present invention. [Figure 14] This is a bottom view showing the fixing member of the buffer according to the second embodiment of the present invention. [Figure 15] This is a plan view showing a fixing member of a buffer according to a third embodiment of the present invention. [Figure 16] This is a cross-sectional view taken along line XVI-XVI in Figure 15, showing a fixing member of a buffer according to a third embodiment of the present invention. [Figure 17] This is a front view showing a fixing member of a buffer according to a third embodiment of the present invention. [Figure 18] This is a bottom view showing a fixing member of a buffer according to a third embodiment of the present invention. [Modes for carrying out the invention]

[0009] [First Embodiment] The buffer of the first embodiment will be described below with reference to Figures 1 to 10. The shock absorber 1 according to the first embodiment is a shock absorber used in suspension devices for automobiles such as railway vehicles, two-wheeled vehicles, and four-wheeled vehicles. Specifically, the shock absorber 1 is a shock absorber used in a suspension device for a four-wheeled motor vehicle. As shown in FIG. 1, the shock absorber 1 is a double-tube type shock absorber provided with a cylinder 4 having an inner tube 2 and an outer tube 3. The inner tube 2 is cylindrical. The outer tube 3 is a bottomed cylindrical tube having a larger diameter than the inner tube 2. The outer tube 3 is provided coaxially with the inner tube 2 on the radially outer side of the inner tube 2. A reservoir chamber 5 is formed between the outer tube 3 and the inner tube 2.

[0010] The outer tube 3 includes a cylindrical portion 8 and a bottom portion 9. The cylindrical portion 8 is cylindrical. The bottom portion 9 closes one axial end of the cylindrical portion 8. A side of the cylindrical portion 8 opposite to the bottom portion 9 is formed as an opening. A mounting eye 10 is fixed to a side of the bottom portion 9 opposite to the cylindrical portion 8 in the axial direction.

[0011] The shock absorber 1 includes a valve body 12 and a rod guide 13. The valve body 12 is annular and is provided on the bottom portion 9 side in the axial direction of the inner tube 2 and the outer tube 3. The rod guide 13 is annular and is provided on the side opposite to the bottom portion 9 in the axial direction of the inner tube 2 and the outer tube 3. The valve body 12 constitutes a base valve 15. The outer peripheral portion of the valve body 12 is formed in a stepped shape, and the valve body 12 is placed on the bottom portion 9 in a state where the large-diameter portion thereof is positioned radially with respect to the cylindrical portion 8. The outer peripheral portion of the rod guide 13 is also formed in a stepped shape, and the large-diameter portion thereof is positioned radially with respect to the cylindrical portion 8 and fitted thereto.

[0012] One axial end of the inner cylinder 2 is fitted to the small-diameter portion of the outer periphery of the valve body 12. One axial end of the inner cylinder 2 is engaged with the bottom portion 9 of the outer cylinder 3 via this valve body 12. Further, the other axial end of the inner cylinder 2 is fitted to the small-diameter portion of the outer periphery of the rod guide 13. The other axial end of the inner cylinder 2 is engaged with the cylindrical portion 8 of the outer cylinder 3 via this rod guide 13. In this state, the inner cylinder 2 is positioned in the radial direction relative to the outer cylinder 3. Here, the space between the valve body 12 and the bottom portion 9 communicates with the space between the inner cylinder 2 and the outer cylinder 3. Therefore, like the space between the inner cylinder 2 and the outer cylinder 3, the space between the valve body 12 and the bottom portion 9 constitutes the reservoir chamber 5.

[0013] The shock absorber 1 includes a seal member 18. The seal member 18 is provided on the opposite side of the rod guide 13 from the bottom portion 9. Similarly to the rod guide 13, this seal member 18 is also fitted to the inner peripheral portion of the cylindrical portion 8. A locking portion 19 is formed at the end of the cylindrical portion 8 opposite to the bottom portion 9. The locking portion 19 is formed by plastically deforming the cylindrical portion 8 radially inward by caulking such as curling. The seal member 18 is sandwiched between the locking portion 19 and the rod guide 13. The seal member 18 closes the opening of the outer cylinder 3, and is specifically an oil seal.

[0014] The shock absorber 1 includes a piston 21. The piston 21 is slidably provided in the cylinder 4. The piston 21 is slidably provided on the inner cylinder 2 of the cylinder 4. The piston 21 divides the interior of the inner cylinder 2 into two chambers: a first chamber 22 and a second chamber 23. The first chamber 22 is provided between the piston 21 and the rod guide 13 in the inner cylinder 2. The second chamber 23 is provided between the piston 21 and the valve body 12 in the inner cylinder 2. The second chamber 23 is defined from the reservoir chamber 5 by the valve body 12. In the cylinder 4, an oil liquid L that is a working fluid is sealed in the first chamber 22 and the second chamber 23. In the cylinder 4, the oil liquid L that is a working fluid and a gas G are sealed in the reservoir chamber 5. Therefore, the shock absorber 1 is a hydraulic shock absorber that uses the oil liquid L as a fluid.

[0015] The shock absorber 1 is equipped with a piston rod 31, which is a rod-shaped shaft member. One end of the piston rod 31 is positioned inside the cylinder 4 and connected to and fixed to the piston 21. The other end of the piston rod 31 extends outside the cylinder 4. The piston rod 31 is made of metal and passes through the first chamber 22. The piston rod 31 does not pass through the second chamber 23. Therefore, the first chamber 22 is a rod-side chamber through which the piston rod 31 passes. The second chamber 23 is a bottom-side chamber on the bottom 9 side of the cylinder 4.

[0016] The piston 21 and piston rod 31 move together. During the extension stroke of the shock absorber 1, when the piston rod 31 increases its protrusion from the cylinder 4, the piston 21 moves toward the first chamber 22. During the compression stroke of the shock absorber 1, when the piston rod 31 decreases its protrusion from the cylinder 4, the piston 21 moves toward the second chamber 23.

[0017] Both the rod guide 13 and the sealing member 18 are annular in shape. The piston rod 31 is slidably inserted inside the respective rod guides 13 and sealing member 18 and extends from the inside to the outside of the cylinder 4. One axial end of the piston rod 31 is fixed to the piston 21 inside the cylinder 4. The other axial end of the piston rod 31 extends outside the cylinder 4 via the rod guide 13 and sealing member 18.

[0018] The rod guide 13 supports the piston rod 31 relative to the cylinder 4, allowing it to move in its axial direction while restricting its radial movement. The rod guide 13 guides the axial movement of the piston rod 31. The outer circumference of the sealing member 18 is in close contact with the outer cylinder 3 of the cylinder 4. The inner circumference of the sealing member 18 slides against the outer circumference of the piston rod 31 as it moves in the axial direction. As a result, the sealing member 18 prevents oil L and gas G inside the cylinder 4 from leaking out.

[0019] The piston rod 31 has a main shaft portion 32 and a mounting shaft portion 33. The mounting shaft portion 33 has a smaller diameter than the main shaft portion 32. The main shaft portion 32 of the piston rod 31 is slidably fitted to the rod guide 13 and the seal member 18. The mounting shaft portion 33 of the piston rod 31 is located inside the cylinder 4 and connected to the piston 21, etc. The end of the main shaft portion 32 on the mounting shaft portion 33 side flares out in a direction perpendicular to the axis.

[0020] As shown in Figure 2, the mounting shaft portion 33 has a base end cylindrical portion 41, an intermediate shaft portion 42, a tip end cylindrical portion 43, and a screw shaft portion 44. The mounting shaft portion 33 is provided with the base end cylindrical portion 41, the intermediate shaft portion 42, the tip end cylindrical portion 43, and the screw shaft portion 44 in this order from the axial main shaft portion 32 side.

[0021] The base end cylindrical portion 41 is a cylindrical part and is located on the axial side of the mounting shaft portion 33, on the main shaft portion 32 side, i.e., on the base end side. The radially outer circumferential surface 41a of the base end cylindrical portion 41 is a continuous cylindrical surface that extends over the entire circumference of the base end cylindrical portion 41.

[0022] The tip-side cylindrical portion 43 is a cylindrical part and is located on the opposite side from the main shaft portion 32, i.e., on the tip side, compared to the base-side cylindrical portion 41 in the axial direction of the mounting shaft portion 33. The radially outer circumferential surface 43a of the tip-side cylindrical portion 43 is a continuous cylindrical surface over the entire circumference of the tip-side cylindrical portion 43. The circumferential surface 43a of the tip-side cylindrical portion 43 is coaxial and has the same diameter as the circumferential surface 41a of the base-side cylindrical portion 41.

[0023] The intermediate shaft portion 42 is provided at an intermediate position in the axial direction of the mounting shaft portion 33. The intermediate shaft portion 42 has a pair of outer end faces 42a, a base end circumferential groove 51, a pair of axial grooves 52, and a tip end circumferential groove 53 on its radially outward side.

[0024] The pair of outer end faces 42a each form a part of a cylindrical surface that is coaxial and of the same diameter as the outer circumferential surface 41a of the base end cylindrical portion 41 and the outer circumferential surface 43a of the tip end cylindrical portion 43. In other words, the pair of outer end faces 42a are located on the same cylindrical surface as the outer circumferential surface 41a of the base end cylindrical portion 41 and the outer circumferential surface 43a of the tip end cylindrical portion 43. The pair of outer end faces 42a are 180 degrees out of phase in the circumferential direction of the intermediate shaft portion 42.

[0025] The base end circumferential groove 51 is provided at the end of the intermediate shaft portion 42 on the base end cylindrical portion 41 side in the axial direction. The base end circumferential groove 51 is recessed inward in the radial direction of both the base end circumferential groove 51 and the intermediate shaft portion 42 from the outer circumferential surface 41a of the base end cylindrical portion 41 and the pair of outer end surfaces 42a of the intermediate shaft portion 42. The base end circumferential groove 51 is an annular shape that extends continuously around the entire circumference of the intermediate shaft portion 42.

[0026] The tip-side circumferential groove 53 is provided at the end of the intermediate shaft portion 42 on the tip-side cylindrical portion 43 side in the axial direction. The tip-side circumferential groove 53 is recessed radially inward from the outer circumferential surface 43a of the tip-side cylindrical portion 43 and the pair of outer end surfaces 42a of the intermediate shaft portion 42. The tip-side circumferential groove 53 is an annular shape that extends continuously around the entire circumference of the intermediate shaft portion 42.

[0027] The pair of axial grooves 52 are recessed inward in the radial direction of the intermediate shaft portion 42 from the pair of outer end faces 42a. The pair of axial grooves 52 are identical in shape, and the inner bottom surface of the intermediate shaft portion 42 in the radial direction is a plane that extends perpendicular to the radial direction of the intermediate shaft portion 42. The pair of axial grooves 52 extend in the axial direction of the piston rod 31. The pair of axial grooves 52 are provided with a 180-degree phase difference in the circumferential direction of the intermediate shaft portion 42 and extend parallel to each other. In the circumferential direction of the intermediate shaft portion 42, the outer end faces 42a and axial grooves 52 are arranged alternately. One end of the pair of axial grooves 52 in the axial direction of the intermediate shaft portion 42 opens into the base end circumferential groove 51, and the other end of the intermediate shaft portion 42 in the axial direction opens into the tip end circumferential groove 53.

[0028] As shown in Figure 3, the passage in the base end circumferential groove 51, the passages in the pair of axial grooves 52, and the passage in the tip end circumferential groove 53 constitute an axial flow path 54 that extends in the axial direction of the piston rod 31.

[0029] The screw shaft portion 44 is located at the end of the mounting shaft portion 33 opposite to the main shaft portion 32 in the axial direction, i.e., at the tip end. The screw shaft portion 44 is cylindrical and has a male thread 57 formed on its radially outward side.

[0030] In the shock absorber 1, for example, the portion of the piston rod 31 protruding from the cylinder 4 as shown in Figure 1 is positioned vertically at the top and supported by the vehicle body. In this case, the shock absorber 1 has a mounting eye 10 fixed to the bottom 9 of the cylinder 4, positioned vertically at the bottom and connected to the wheel side. If the shock absorber 1 is a single-tube type, it is also possible to configure it in the opposite way, with the cylinder 4 side supported by the vehicle body and the piston rod 31 connected to the wheel side.

[0031] As shown in Figure 3, the piston 21 is composed of a metal piston body 61 supported by a piston rod 31 and an annular synthetic resin friction member 62 that is integrally mounted on the outer surface of the piston body 61 and slides inside the inner cylinder 2.

[0032] The piston body 61 has multiple passage holes 71 (only one is shown in Figure 3 due to the cross-sectional view) and an annular passage groove 72 that connects the ends of these passage holes 71 opposite to the first chamber 22. The piston body 61 also has multiple passage holes 75 (only one is shown in Figure 3 due to the cross-sectional view) and an annular passage groove 76 that connects the ends of these passage holes 75 on the first chamber 22 side. The multiple passage holes 71 are formed in the circumferential direction of the piston body 61, with one passage hole 75 in between each of them.

[0033] Multiple passages in the passage holes 71 and passages in the passage grooves 72 constitute a piston passage 81 that allows the piston 21 to pass through in the axial direction of the piston 21 and connect the first chamber 22 and the second chamber 23. Multiple passages in the passage holes 75 and passages in the passage grooves 76 constitute a piston passage 82 that allows the piston 21 to pass through in the axial direction of the piston 21 and connect the first chamber 22 and the second chamber 23.

[0034] The piston passage 81 is provided with a first damping force generating mechanism 85, which is a valve that opens and closes the piston passage 81 to generate damping force. The first damping force generating mechanism 85 is located on the second chamber 23 side, which is one axial end of the piston 21, and is attached to the piston rod 31. Because the first damping force generating mechanism 85 is located on the second chamber 23 side, during the piston passage 81's movement toward the first chamber 22 side, i.e., the extension stroke, the oil L that flows out from the first chamber 22 flows toward the second chamber 23. The first damping force generating mechanism 85 provided for the piston passage 81 is an extension-side valve mechanism that generates damping force by suppressing the flow of oil L from the extension-side piston passage 81 to the second chamber 23.

[0035] The piston passage 82 is provided with a first damping force generating mechanism 86, which is a valve that opens and closes the piston passage 82 to generate damping force. The first damping force generating mechanism 86 is located on the first chamber 22 side, which is the other axial end of the piston 21, and is attached to the piston rod 31. Because the first damping force generating mechanism 86 is located on the first chamber 22 side, during the movement of the piston 21 toward the second chamber 23 side, i.e., the compression stroke, the oil liquid L that flows out from the second chamber 23 flows toward the first chamber 22. The first damping force generating mechanism 86 provided for the piston passage 82 is a compression-side valve mechanism that generates damping force by suppressing the flow of oil liquid L from the compression-side piston passage 82 toward the first chamber 22.

[0036] As a result, the piston passage 81 and the piston passage 82 are connected so that the fluid, oil L, flows between the first chamber 22 and the second chamber 23 as the piston 21 moves. In this way, the oil L passes through the piston passage 81 when the piston rod 31 and the piston 21 move in the extension direction, and the oil L passes through the piston passage 82 when the piston rod 31 and the piston 21 move in the compression direction.

[0037] The piston passage 82 is provided as part of the first passage 132, which will be described later, and the first damping force generating mechanism 86 is provided in the first passage 132. The first damping force generating mechanism 86 is provided in the first passage 132 formed in the piston 21 and generates damping force. The piston passage 81 is also provided as part of the first passage 152, which will be described later, and the first damping force generating mechanism 85 is provided in the first passage 152. The first damping force generating mechanism 85 is provided in the first passage 152 formed in the piston 21 and generates damping force.

[0038] The piston body 61 consists of two components: a first piston body 91 and a second piston body 92. The first piston body 91 constitutes the portion of the piston body 61 on the second chamber 23 side in the axial direction, and the second piston body 92 constitutes the portion of the piston body 61 on the first chamber 22 side in the axial direction.

[0039] The first piston body 91 has a roughly disc shape. A circular fixing hole 101 is formed in the radial center of the first piston body 91, penetrating the first piston body 91 in the axial direction. The fixing hole 101 is a part of the first piston body 91 into which the mounting shaft portion 33 of the piston rod 31 is fitted.

[0040] A passage groove 102 extending radially from the first piston body 91 is formed on the end face of the first piston body 91 on the second piston body 92 side in the axial direction. The passage within the passage groove 102 is a piston internal flow path 103 that communicates with the piston passage 81.

[0041] The passage groove 72 described above is formed at the end of the first piston body 91 on the second chamber 23 side in the axial direction. At the end of the first piston body 91 on the second chamber 23 side in the axial direction, an annular valve seat portion 105, which constitutes part of the first damping force generating mechanism 85, is formed radially outward from the opening of the passage groove 72 on the second chamber 23 side. In addition, at the end of the piston body 61 on the second chamber 23 side in the axial direction, an inner seat portion 106 is formed radially inward from the opening of the passage groove 72 on the second chamber 23 side.

[0042] The first piston body 91 has an engaging projection 108 that protrudes outward along the axial direction of the first piston body 91 from the end face of the first piston body 91 on the second piston body 92 side in the axial direction of the first piston body 91. The engaging projection 108 is partially provided in the circumferential direction of the first piston body 91.

[0043] The second piston body 92 has a roughly disc shape. A circular fixing hole 111 is formed in the radial center of the second piston body 92, penetrating the second piston body 92 in the axial direction. The fixing hole 111 is a part of the second piston body 92 into which the mounting shaft portion 33 of the piston rod 31 is fitted.

[0044] The passage groove 76 described above is formed at the end of the second piston body 92 on the first chamber 22 side in the axial direction. At the end of the second piston body 92 on the first chamber 22 side in the axial direction, an annular valve seat portion 115, which constitutes part of the first damping force generating mechanism 86, is formed radially outward from the opening of the passage groove 76 on the first chamber 22 side. In addition, at the end of the piston body 61 on the first chamber 22 side in the axial direction, an inner seat portion 116 is formed radially inward from the opening of the passage groove 76 on the first chamber 22 side.

[0045] The second piston body 92 has an engagement recess 118 formed on its end face on the first piston body 91 side in the axial direction, which is recessed inward along the axial direction of the second piston body 92. The engagement recess 118 is partially provided in the circumferential direction of the second piston body 92.

[0046] The first piston body 91 and the second piston body 92 are connected by engaging the engaging projection 108 of the first piston body 91 with the engaging recess 118 of the second piston body 92. This connects the first piston body 91 and the second piston body 92 in a circumferentially positioned manner so as to form piston passages 81 and 82. In this state, the friction member 62 is placed over the radially outer sides of the first piston body 91 and the second piston body 92. As a result, the first piston body 91 and the second piston body 92 are integrated to form the piston body 61, and the first piston body 91, the second piston body 92, and the friction member 62 are integrated to form the piston 21.

[0047] In the first piston body 91, the opening on the second chamber 23 side of the compression piston passage 82 is located radially outward of the valve seat portion 105. In the second piston body 92, the opening on the first chamber 22 side of the extension piston passage 81 is located radially outward of the valve seat portion 115.

[0048] The piston 21 has a fixing hole 111 that fits into the outer circumferential surface 41a of the base end cylindrical portion 41 of the piston rod 31 as shown in Figure 2, and a fixing hole 101 as shown in Figure 3 that fits into the pair of outer end surfaces 42a of the intermediate shaft portion 42 of the piston rod 31 as shown in Figure 2. In the axial direction of the piston rod 31, the piston internal passage 103 is positioned to overlap with the base end circumferential groove 51 of the piston rod 31. This allows the piston internal passage 103 to communicate with the axial passage 54 of the piston rod 31 without having to align the circumferential phase of the piston 21 with the piston rod 31.

[0049] The compression-side first damping force generating mechanism 86 includes the valve seat portion 115 of the piston 21. The first damping force generating mechanism 86 has, in order from the axial piston 21 side, one disc 121 and multiple discs 122. On the axial side of the multiple discs 122 opposite to disc 121, in order from the multiple discs 122 side, one disc 123, one disc 124, and one annular member 125 are provided. Discs 121 to 124 and the annular member 125 are all perforated circular flat plates, and the outer circumferential surface 41a of the base end cylindrical portion 41 of the mounting shaft portion 33, as shown in Figure 2, is fitted inside each of them.

[0050] As shown in Figure 3, the disc 121 has an outer diameter that is larger than the outer diameter of the inner seat portion 116 of the piston 21 and smaller than the inner diameter of the valve seat portion 115. The disc 121 is in constant contact with the inner seat portion 116.

[0051] The disc 122 closest to disc 121 in the axial direction has an outer diameter equal to the outer diameter of the valve seat portion 115 of the piston 21. The disc 122 closest to disc 121 in the axial direction is capable of seating on the valve seat portion 115.

[0052] The outer diameter of disc 123 is smaller than the outer diameter of the multiple discs 122, and is slightly smaller than the outer diameter of the inner seat portion 116 of the piston 21. Disc 124 has a larger outer diameter than disc 123.

[0053] The annular member 125 has an outer diameter smaller than the outer diameter of the disc 124 and a larger outer diameter than the outer diameter of the end of the main shaft portion 32 of the piston rod 31 on the mounting shaft portion 33 side in the axial direction. The annular member 125 is thicker and more rigid than the discs 121 to 124 and abuts against the end of the main shaft portion 32 on the mounting shaft portion 33 side in the axial direction.

[0054] Multiple discs 122 constitute a compression-side valve member 131 that can seat on and off the valve seat portion 115. The valve member 131 is flexible and, by separating from the valve seat portion 115, connects the piston passage 82 to the first chamber 22. At that time, the valve member 131 suppresses the flow of oil L between itself and the valve seat portion 115, thereby generating a damping force. By seating on the valve seat portion 115, the valve member 131 blocks communication between the piston passage 82 and the first chamber 22. The annular member 125, together with the discs 124, contacts the valve member 131 to suppress deformation of the valve member 131 beyond a specified limit in the opening direction.

[0055] The piston passage 82 and the passage between the valve member 131 and the valve seat portion 115 that appear when the valve is opened constitute the first passage 132. The first passage 132 is provided in the piston 21. The first passage 132 is a compression-side passage through which oil liquid L flows from the second chamber 23, which becomes the upstream region of the cylinder 4, to the first chamber 22, which becomes the downstream region, as the piston 21 moves toward the second chamber 23. The compression-side first damping force generating mechanism 86, which generates damping force, includes the valve member 131 and the valve seat portion 115. The first damping force generating mechanism 86 is provided in the first passage 132. The first passage 132 is provided in the piston 21 including the valve seat portion 115, and oil liquid L passes through it when the piston rod 31 and the piston 21 move toward the compression side.

[0056] Here, the compression-side first damping force generating mechanism 86 is not provided with a fixed orifice in either the valve seat portion 115 or the valve member 131 that abuts it, which would connect the first chamber 22 and the second chamber 23 even when the valve seat portion 115 and the valve member 131 are in contact. Therefore, the first passage 132 is not a passage that constantly connects the first chamber 22 and the second chamber 23.

[0057] The extension-side first damping force generating mechanism 85 includes the valve seat portion 105 of the piston 21. The first damping force generating mechanism 85 has, in order from the axial piston 21 side, one disc 141 and multiple discs 142. On the axial side of the multiple discs 142 opposite to disc 141, one disc 143 and one disc 144 are provided, in order from the multiple discs 142 side. Discs 141 to 144 are all perforated circular flat plates, and each has a pair of outer end faces 42a of the intermediate shaft portion 42 of the mounting shaft portion 33, as shown in Figure 2, fitted to its inside.

[0058] The disc 141 has an outer diameter that is larger than the outer diameter of the inner seat portion 106 of the piston 21, but smaller than the inner diameter of the valve seat portion 105. The disc 141 is in constant contact with the inner seat portion 106.

[0059] The multiple discs 142 are arranged such that the disc 142 closest to disc 141 in the axial direction has an outer diameter equal to the outer diameter of the valve seat portion 105 of the piston 21. The multiple discs 142 are arranged such that the disc 142 closest to disc 141 in the axial direction can seat on the valve seat portion 105.

[0060] The disc 143 has a smaller outer diameter than any of the multiple discs 142 and has an outer diameter equivalent to the outer diameter of the inner seat portion 106 of the piston 21. Disc 144 has a larger outer diameter than disc 143.

[0061] Multiple discs 142 constitute an extendable valve member 151 that can seat on and off the valve seat portion 105. The valve member 151 is flexible and, by separating from the valve seat portion 105, connects the piston passage 81 to the second chamber 23. At that time, the valve member 151 suppresses the flow of oil L between itself and the valve seat portion 105, thereby generating a damping force. By seating on the valve seat portion 105, the valve member 151 blocks communication between the piston passage 81 and the second chamber 23.

[0062] The piston passage 81 and the passage between the valve member 151 and the valve seat portion 105 that appear when the valve is opened constitute the first passage 152. The first passage 152 is formed in the piston 21. The first passage 152 is an extension-side passage through which oil liquid L flows from the first chamber 22, which becomes the upstream region of the cylinder 4, to the second chamber 23, which becomes the downstream region, as the piston 21 moves toward the first chamber 22. The extension-side first damping force generating mechanism 85, which generates damping force, includes the valve member 151 and the valve seat portion 105. The first damping force generating mechanism 85 is provided in this first passage 152. The first passage 152 is provided in the piston 21 including the valve seat portion 105, and oil liquid L passes through it when the piston rod 31 and the piston 21 move toward the extension side.

[0063] In the extension-side first damping force generating mechanism 85, neither the valve seat portion 105 nor the valve member 151 that abuts against it has a fixed orifice that connects the first chamber 22 and the second chamber 23 even when the valve seat portion 105 and the valve member 151 are in contact. Therefore, the first passage 152 is not a flow path that constantly connects the first chamber 22 and the second chamber 23.

[0064] The internal piston passage 103 provided in the piston 21 communicates with the first chamber 22 via a portion of the piston passage 81 that is closer to the first chamber 22 than the internal piston passage 103. The portion of the piston passage 81 provided in the piston 21 that is closer to the first chamber 22 than the internal piston passage 103, and the internal piston passage 103, together constitute the first chamber side passage 156. At least a portion of the first chamber side passage 156, the internal piston passage 103, is provided parallel to a portion of the first passage 152 that is closer to the second chamber 23 than the internal piston passage 103.

[0065] The piston 21, disc 121, valve member 131, disc 141, and valve member 151 constitute a first structural member 155 that divides the inside of the inner cylinder 2 of the cylinder 4 into a first chamber 22 and a second chamber 23. The first structural member 155 divides the inside of the inner cylinder 2 of the cylinder 4 into a first chamber 22 which is the upstream region during the extension stroke and a second chamber 23 which is the downstream region during the extension stroke. The first structural member 155 has circular fixing holes 101, 111 that penetrate in the axial direction, a first passage 152 that can connect the first chamber 22 which is the upstream region during the extension stroke and the second chamber 23 which is the downstream region, a valve member 151 that is flexible and can close the first passage 152, and a first chamber side passage 156 which is provided parallel to the first passage 152, with at least a part of the piston internal passage 103 being.

[0066] As shown in Figure 4, a second damping force generating mechanism 140 is provided on the side of disk 144 opposite to disk 143 in the axial direction.

[0067] The second damping force generating mechanism 140 has, on the side of the disc 144 opposite to the disc 143 in the axial direction, one disc 160, one spring member 161, multiple discs 162, one valve member 163, and one valve seat member 166 with one O-ring 165 on its outer circumference. The second damping force generating mechanism 140 also has, on the side of the valve seat member 166 opposite to the valve member 163 in the axial direction, one valve member 167, multiple discs 168, one spring member 169, and one disc 170, on the side of the valve seat member 166 in the axial direction, one valve member 167, multiple discs 168, one spring member 169, and one disc 170. The second damping force generating mechanism 140 also has, on the side of the disc 170 opposite to the spring member 169 in the axial direction, one disc 172, one disc 173, and one disc 174, on the side of the disc 170 in the axial direction, one disc 172, one disc 173, and one disc 174, on the side of the disc 170 in the axial direction. Furthermore, the second damping force generating mechanism 140 has, on the side of the disk 174 opposite to the disk 173 in the axial direction, a plurality of disks 176, a single disc spring 177, and a single cap member 178, in order from the disk 174 side. The second damping force generating mechanism 140, including the valve seat member 166, is located in the second chamber 23.

[0068] Discs 160, 162, 168, 170, 172, 173, 174, 176, spring members 161, 169, valve members 163, 167, valve seat member 166, disc spring 177, and cap member 178 are fitted to the inside of the mounting shaft portion 33 of the piston rod 31. At the same time, discs 160, spring member 161, disc 162, valve member 163, and valve seat member 166 are fitted to the inside of the pair of outer end faces 42a of the intermediate shaft portion 42 of the mounting shaft portion 33, as shown in Figure 2. Furthermore, as shown in Figure 4, the valve seat member 166, valve member 167, disc 168, spring member 169, disc 170, disc 172, disc 173, disc 174, disc 176, disc spring 177, and cap member 178 are fitted to the inside of the outer circumferential surface 43a of the tip side cylindrical portion 43 of the mounting shaft portion 33, as shown in Figure 2.

[0069] As shown in Figure 3, the mounting shaft portion 33 of the piston rod 31 has a threaded shaft portion 44 positioned on the portion that protrudes beyond the cap member 178. A fixing member 182 is screwed onto the male thread 57 on the outer circumference of this threaded shaft portion 44. The fixing member 182 is in contact with the cap member 178.

[0070] As shown in Figure 4, the discs 160, 162, 168, 170, 172, 173, 174, 176, spring members 161, 169, valve members 163, 167, valve seat member 166, disc spring 177, and cap member 178 are each clamped axially by the main shaft portion 32 and fixing member 182 of the piston rod 31, as shown in Figure 3, at least on their radially inner circumference.

[0071] As shown in Figure 4, the discs 160, 162, 168, 170, 172, 173, and 176, and the valve members 163 and 167 are all perforated circular flat plates.

[0072] The cap member 178 is made of metal and is a single-piece molded cylindrical part with a bottom. The cap member 178 has a bottom portion 191, an intermediate tapered portion 192, and an outer cylindrical portion 193. As shown in Figure 3, the outer diameter of the cap member 178 is smaller than the outer diameter of the piston 21.

[0073] As shown in Figure 4, the bottom portion 191 is a perforated disc-shaped plate. The intermediate tapered portion 192 extends from the outer peripheral edge of the bottom portion 191 in one axial direction of the bottom portion 191, while expanding in diameter. The intermediate tapered portion 192 is annular in shape.

[0074] The outer cylindrical portion 193 extends in the axial direction of the intermediate tapered portion 192 from the edge opposite to the bottom portion 191 of the intermediate tapered portion 192, and in the direction opposite to the bottom portion 191. The outer cylindrical portion 193 is cylindrical in shape.

[0075] The cap member 178 is fitted to the inner circumference of the bottom portion 191 by the tip side cylindrical portion 43 of the mounting shaft portion 33 of the piston rod 31 at the outer circumferential surface 43a shown in Figure 2. As shown in Figure 4, the bottom portion 191 has multiple (only one is shown in Figure 4 due to the cross-sectional view) communication holes 195. The multiple communication holes 195 penetrate the bottom portion 191 in the axial direction. The multiple communication holes 195 are arranged at equal intervals in the circumferential direction of the bottom portion 191 at positions equidistant from the center of the bottom portion 191. The communication holes 195 are in the shape of an arc extending in the circumferential direction of the bottom portion 191. The cap member 178 is oriented such that the bottom portion 191 is on the opposite side from the disk 144 to the outer cylindrical portion 193 in its axial direction. The multiple communication holes 195 are provided on the end face 191a of the bottom portion 191 that is opposite to the outer cylindrical portion 193 in the axial direction.

[0076] The valve seat member 166, valve member 167, discs 168, 170, 172, 173, 174, and 176, spring member 169, and disc spring 177 are arranged radially inside the cap member 178.

[0077] The disc spring 177 is flexible. The disc spring 177 has an inner annular portion 201 and an outer tapered portion 202.

[0078] The inner annular portion 201 is a perforated circular flat plate. The inner annular portion 201 has a passage hole 205 that penetrates the inner annular portion 201 in the axial direction. The passage hole 205 is arc-shaped and extends in the circumferential direction of the inner annular portion 201. The outer tapered portion 202 is a conical cylinder that extends radially outward and axially in one direction from the outer peripheral edge of the inner annular portion 201.

[0079] The disc spring 177 contacts the bottom 191 of the cap member 178 at its inner annular portion 201, and the outer tapered portion 202 moves further away from the bottom 191 in the axial direction of the bottom 191 as it moves radially outward. When the inner ring portion 201 of the disc spring 177 contacts the bottom portion 191 of the cap member 178, the passage hole 205 of the inner ring portion 201 communicates with the communication hole 195 of the cap member 178.

[0080] The outer diameter of the disc 176 is smaller than the outer diameter of the inner annular portion 201 of the disc spring 177, and the outer diameter does not obstruct the passage hole 205 of the disc spring 177. The disc 174 is flexible. The outer diameter of the disc 174 is larger than the outer diameter of the disc spring 177, i.e., the outer diameter of the outer tapered portion 202. The disc spring 177 has a circular outer peripheral edge that is radially outward of the outer tapered portion 202 and presses against the outer peripheral edge of the disc 174 over its entire circumference.

[0081] The disk 174 has a through hole 211 that penetrates the disk 174 in the axial direction. In the disk 174, the through hole 211 is formed in a position that is not blocked by the disk 176.

[0082] The disc 173 is flexible. The outer diameter of the disc 173 is smaller than the outer diameter of the disc 174. The outer diameter of the disc 173 is sized to close the through hole 211 of the disc 174. The disc 173 contacts the disc 174 all around. When this happens, the disc 173 closes the through hole 211 of the disc 174. The disc 173 opens the through hole 211 of the disc 174 when the disc 174 elastically deforms toward the bottom 191 side of the cap member 178, while elastically deforming the outer tapered portion 202 of the disc spring 177.

[0083] The outer diameter of disc 172 is smaller than the outer diameter of disc 173 and also smaller than the outer diameter of disc 176. The outer diameter of disc 170 is larger than that of disc 173, and slightly smaller than that of disc 174.

[0084] The spring member 169 is flexible. The spring member 169 has a base plate portion 221 and a plurality of spring plate portions 222.

[0085] The base plate portion 221 is a perforated circular flat plate. The mounting shaft portion 33 is fitted into the inner circumference of the base plate portion 221.

[0086] Multiple spring plate portions 222 extend radially from the outer peripheral edge of the substrate portion 221. The further outward the multiple spring plate portions 222 are from the substrate portion 221 in the axial direction, the further they are from the substrate portion 221 in the radial direction.

[0087] The spring member 169 contacts the disk 170 on the substrate portion 221. The multiple spring plate portions 222 are further away from the disk 170 in the axial direction of the substrate portion 221 as they are further outward in the radial direction of the substrate portion 221.

[0088] The outer diameter of disc 168 is smaller than the outer diameter of the base portion 221 of the spring member 169, but larger than the outer diameter of disc 172. Disc 168 contacts the base portion 221 of the spring member 169.

[0089] The valve member 167 is flexible. The outer diameter of the valve member 167 is larger than the maximum outer diameter of the spring member 169.

[0090] As shown in Figures 5 and 6, the valve seat member 166 is a perforated disc shape. The valve seat member 166 has a central hole 231 formed at its radial center, which penetrates through the valve seat member 166 in the axial direction. In other words, the central hole 231 extends in the axial direction of the valve seat member 166 and penetrates the valve seat member 166 in the axial direction. As shown in Figure 4, the mounting shaft portion 33 of the piston rod 31 is inserted through the central hole 231 of the valve seat member 166.

[0091] As shown in Figures 5 and 6, the central hole 231 has a first inner circumferential wall 232 and a second inner circumferential wall 233.

[0092] The first inner circumferential wall 232 has a cylindrical inner surface. As shown in Figure 4, the first inner circumferential wall 232 penetrates the valve seat member 166 in the axial direction.

[0093] As shown in Figures 5 and 6, the second inner circumferential wall 233 is recessed radially outward from the inner surface of the first inner circumferential wall 232. The inner surface of the second inner circumferential wall 233 is semi-cylindrical. As shown in Figure 4, the second inner circumferential wall 233 extends linearly along the axial direction of the valve seat member 166 and penetrates the valve seat member 166 in the axial direction. The central hole 231 has one or more second inner circumferential walls 233. Here, as shown in Figures 5 and 6, the central hole 231 has a plurality of second inner circumferential walls 233 that are equally spaced in the circumferential direction of the first inner circumferential wall 232.

[0094] The central hole 231 has an insertion hole 234 on the inside of the first inner circumferential wall 232 through which the mounting shaft portion 33 of the piston rod 31 is inserted, as shown in Figure 4, and an expanded portion 235 on the inside of the second inner circumferential wall 233 that extends radially outward from the insertion hole 234. The valve seat member 166 has an insertion hole 234 and one or more expanded portions 235 that extend radially from the insertion hole 234. Here, as shown in Figures 5 and 6, the valve seat member 166 has a plurality of expanded portions 235 that are equally spaced in the circumferential direction of the insertion hole 234. As shown in Figure 4, both the insertion hole 234 and the expanded portions 235 extend from one end face to the other end face in the axial direction of the valve seat member 166 and penetrate the valve seat member 166.

[0095] The mounting shaft portion 33 of the piston rod 31 fits into the central hole 231 at the first inner circumferential wall 232, at the pair of outer end faces 42a of the intermediate shaft portion 42 shown in Figure 2 and the outer circumferential surface 43a of the tip side cylindrical portion 43. Then, as shown in Figure 4, the second inner circumferential wall 233 is spaced radially apart from the mounting shaft portion 33 of the piston rod 31. The expansion portion 235 is formed from the side of the valve seat member 166 opposite to the side facing the first structural member 155 shown in Figure 3, to a position that communicates with the axial flow path 54. In the axial direction of the piston rod 31, the central hole 231 is aligned with the tip side circumferential groove 53 of the piston rod 31. Therefore, the central hole 231 communicates directly or indirectly with the tip side circumferential groove 53 of the piston rod 31; in this case, it communicates directly. An intermediate chamber 237 is formed by the second inner circumferential wall 233 of the valve seat member 166 and the mounting shaft portion 33 of the piston rod 31. The circumferential groove 53 on the tip side of the piston rod 31 allows the intermediate chamber 237 to communicate with the axial flow path 54 without having to align the circumferential phase of the valve seat member 166 with respect to the piston rod 31.

[0096] The valve seat member 166 has an inner seat portion 241 and a valve seat portion 242 at one end on the axial side. As shown in Figure 5, the inner seat portion 241 is annular in shape, surrounding the central hole 231. The valve seat portion 242 extends radially outward from the inner seat portion 241.

[0097] As shown in Figure 4, the valve seat member 166 has an inner seat portion 244 and a valve seat portion 245 at the other end on the axial side. As shown in Figure 6, the inner seat portion 244 is annular in shape, surrounding the central hole 231. The valve seat portion 245 extends radially outward from the inner seat portion 244.

[0098] As shown in Figure 4, the valve seat member 166 has a main body portion 247 between its axial inner seat portion 241 and valve seat portion 242 and the inner seat portion 244 and valve seat portion 245. The main body portion 247 is a perforated disc shape.

[0099] The inner seat portion 241 protrudes from the inner peripheral edge on one axial side of the main body portion 247, along the axial direction of the main body portion 247. The valve seat portion 242 protrudes radially outward from the inner seat portion 241, along the axial direction of the main body portion 247, on the same side as the inner seat portion 241.

[0100] The inner seat portion 241 has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 247. The valve seat portion 242 also has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 247. The protruding end faces of the inner seat portion 241 and the protruding end faces of the valve seat portion 242 are arranged on the same plane, extending in a direction perpendicular to the axis of the valve seat member 166.

[0101] The inner seat portion 244 protrudes from the inner peripheral edge of the main body portion 247 on the side opposite to the inner seat portion 241 in the axial direction, along the axial direction of the main body portion 247, and toward the side opposite to the inner seat portion 241. The valve seat portion 245 protrudes radially outward from the inner seat portion 244, along the axial direction of the main body portion 247, toward the same side as the inner seat portion 244.

[0102] The inner seat portion 244 has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 247. The valve seat portion 245 also has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 247. The protruding end faces of the inner seat portion 244 and the protruding end faces of the valve seat portion 245 are arranged on the same plane, extending in a direction perpendicular to the axis of the valve seat member 166.

[0103] As shown in Figure 5, the inner sheet portion 241 has an annular portion 251 and a plurality of protruding portions 252. The annular portion 251 is circular in shape and surrounds the central hole 231.

[0104] The protruding portions 252 extend outward from the outer peripheral edge of the annular portion 251 in the radial direction of the annular portion 251. Multiple protruding portions 252 are arranged at intervals in the circumferential direction of the annular portion 251.

[0105] The inner seat portion 241 has radial communication grooves 253 that penetrate the annular portion 251 in the radial direction of the annular portion 251. Multiple radial communication grooves 253 are formed at equal intervals in the circumferential direction of the annular portion 251. As shown in Figure 4, the radial communication grooves 253 are formed recessed in the axial direction of the valve seat member 166 from the end face of the inner seat portion 241 opposite to the main body portion 247.

[0106] As shown in Figure 5, each radial communication groove 253 is in phase with one of the multiple second inner circumferential walls 233 of the central hole 231 in the circumferential direction of the annular portion 251, and communicates with the corresponding second inner circumferential wall 233. Each of the multiple radial communication grooves 253 is provided between adjacent protrusions 252 in the circumferential direction of the annular portion 251.

[0107] The valve seat portion 242 is a non-circular, petal-shaped irregular seat. The valve seat portion 242 has multiple valve seat components 255. These valve seat components 255 are the same shape and are arranged at equal intervals in the circumferential direction of the valve seat member 166. Note that these valve seat components 255 do not need to be the same shape; they may be of two or more different shapes or have different shapes from each other. They may also be arranged at unequal intervals in the circumferential direction of the valve seat member 166. With this configuration, the valve opening pressure applied to the valve member 163, described later, can be made uneven in the circumferential direction, thereby allowing the valve opening timing to be varied and the damping force characteristics to be smoothly changed.

[0108] The valve seat component 255 has a pair of extensions 256 and a connecting portion 257. Both extensions 256 extend outward in the radial direction of the annular portion 251 from the outer peripheral edge of the annular portion 251 of the inner seat portion 241. The pair of extensions 256 are spaced apart in the circumferential direction of the annular portion 251.

[0109] The connecting portion 257 connects the radially outer ends of the annular portion 251 of the pair of extension portions 256. The connecting portion 257 extends in the circumferential direction of the annular portion 251. The connecting portion 257 has an arc shape centered on the central axis of the valve seat member 166.

[0110] Here, a pair of protruding portions 252 are arranged on the inner side of the valve seat member 166 of the valve seat component 255, adjacent to each other in the circumferential direction of the inner seat portion 241, and a radial communication groove 253 is arranged between these pairs of protruding portions 252. Therefore, a pair of protruding portions 252 and a radial communication groove 253 are arranged on the inner side of the valve seat member 166 of each of the multiple valve seat components 255 in the circumferential direction.

[0111] A passage recess 258 is formed inside each of the multiple valve seat components 255, between it and the inner seat portion 241. The passage recess 258 is formed by being surrounded by a part of the inner seat portion 241 and the valve seat component 255. As shown in Figure 4, the passage recess 258 is recessed in the axial direction of the valve seat member 166 from the protruding end surface of the inner seat portion 241 and the protruding end surface of the valve seat component 255. The bottom surface of the passage recess 258 is formed by the main body portion 247. As shown in Figure 5, a passage recess 258 is formed inside all of the valve seat components 255.

[0112] A passage hole 259 is formed at the center of the passage recess 258 in the circumferential direction of the valve seat member 166. The passage hole 259 is positioned between a pair of protruding portions 262 within the passage recess 258 in which it is formed, in the circumferential direction of the valve seat member 166. As shown in Figure 4, the passage hole 259 penetrates the valve seat member 166 axially by passing through the main body portion 247 in the axial direction. The passage hole 259 is a straight hole parallel to the central axis of the valve seat member 166. As shown in Figure 5, passage holes 259 are formed on the bottom surface of all passage recesses 258.

[0113] As shown in Figure 6, the inner sheet portion 244 has an annular portion 261 and a plurality of protruding portions 262. The annular portion 261 is circular in shape and surrounds the central hole 231.

[0114] The protruding portions 262 extend outward from the outer peripheral edge of the annular portion 261 in the radial direction of the annular portion 261. Multiple protruding portions 262 are arranged at intervals in the circumferential direction of the annular portion 261.

[0115] Multiple communication grooves 263 are formed in the inner seat portion 244 at equal intervals in the circumferential direction of the annular portion 261, traversing the annular portion 261 in the radial direction. As shown in Figure 4, the communication grooves 263 are formed as recesses in the axial direction of the valve seat member 166 from the end surface of the inner seat portion 244 opposite to the main body portion 247.

[0116] As shown in Figure 6, each of the multiple communication grooves 263 is in phase with one of the multiple second inner circumferential walls 233 of the central hole 231 in the circumferential direction of the annular portion 261, and communicates with the corresponding second inner circumferential wall 233. Each of the multiple communication grooves 263 is provided between adjacent protrusions 262 in the circumferential direction of the annular portion 251.

[0117] The valve seat portion 245 is a non-circular, petal-shaped irregular seat. The valve seat portion 245 has multiple valve seat components 265. These valve seat components 265 are the same shape and are arranged at equal intervals in the circumferential direction of the valve seat member 166. Note that these valve seat portions 245 do not need to be the same shape; they may be of two or more different shapes or have different shapes from each other. They may also be arranged at unequal intervals in the circumferential direction of the valve seat member 166. With this configuration, the valve opening pressure applied to the valve member 167, described later, can be made uneven in the circumferential direction, thereby allowing the valve opening timing to be varied and the damping force characteristics to be smoothly changed.

[0118] In the annular portion 261 of the inner seat portion 244, a communication groove 263 is positioned between two valve seat components 265 adjacent to each other in the circumferential direction of the valve seat member 166. Therefore, the communication groove 263 is formed in the portion of the inner seat portion 244 that is located outside the valve seat portion 245.

[0119] The valve seat component 265 has a pair of extensions 266 and a connecting portion 267. Both extensions 266 extend outward in the radial direction of the annular portion 261 from the outer peripheral edge of the annular portion 261 of the inner seat portion 244. The pair of extensions 266 are spaced apart in the circumferential direction of the annular portion 261.

[0120] The connecting portion 267 connects the radially outer ends of the annular portion 261 of the pair of extension portions 266. The connecting portion 267 extends in the circumferential direction of the annular portion 261. The connecting portion 267 has an arc shape centered on the central axis of the valve seat member 166.

[0121] Here, a pair of protruding portions 262 are arranged on the inner side in the circumferential direction of the valve seat member 166 of the valve seat component 265, and adjacent to each other in the circumferential direction of the inner seat portion 244. Therefore, a pair of protruding portions 262 are arranged on the inner side in the circumferential direction of each valve seat member 166 of the multiple valve seat components 265.

[0122] Inside each of the multiple valve seat components 265, a passage recess 268 is formed between it and the inner seat portion 244. The passage recess 268 is formed by being surrounded by a part of the inner seat portion 244 and the valve seat component 265.

[0123] As shown in Figure 4, the passage recess 268 is recessed in the axial direction of the valve seat member 166 from the protruding end surface of the inner seat portion 244 and the protruding end surface of the valve seat component 265. The bottom surface of the passage recess 268 is formed by the main body portion 247. As shown in Figure 6, the passage recess 268 is formed inside all valve seat components 265.

[0124] A passage hole 269 is formed at the center of the passage recess 268 in the circumferential direction of the valve seat member 166. The passage hole 269 is positioned between a pair of protruding portions 262 within the passage recess 268 in which it is formed, in the circumferential direction of the valve seat member 166. As shown in Figure 4, the passage hole 269 penetrates the valve seat member 166 axially by passing through the main body portion 247 in the axial direction. The passage hole 269 is a straight hole parallel to the central axis of the valve seat member 166. As shown in Figure 6, passage holes 269 are formed on the bottom surface of all passage recesses 268.

[0125] Here, the circumferential arrangement pitch of the valve seat members 166 of the multiple valve seat components 255 shown in Figure 5 is the same as the circumferential arrangement pitch of the valve seat members 166 of the multiple valve seat components 265 shown in Figure 6. Furthermore, the valve seat components 255 and 265 are offset from each other by half a phase in terms of their arrangement pitch in the circumferential direction of the valve seat member 166.

[0126] As shown in Figure 5, the passage hole 269 is located between adjacent valve seat components 255 in the circumferential direction of the valve seat member 166. Therefore, the passage hole 269 is located outside the range of the valve seat portion 242.

[0127] Furthermore, as shown in Figure 6, the passage hole 259 is located between adjacent valve seat components 265 in the circumferential direction of the valve seat member 166. Therefore, the passage hole 259 is located outside the range of the valve seat portion 245.

[0128] As shown in Figure 4, the passage within the passage hole 259 and the passage within the passage recess 258 through which the passage hole 259 opens constitute the passage portion 281 provided on the valve seat member 166. Multiple passage portions 281 are provided on the valve seat member 166 at equal intervals in the circumferential direction of the valve seat member 166. The passage portions 281 communicate with the passage within the radial communication groove 253 and the passage within the communication groove 263.

[0129] The passage hole 269 and the passage within the passage recess 268 through which the passage hole 269 opens constitute the passage portion 282 provided on the valve seat member 166. Multiple passage portions 282 are provided on the valve seat member 166 at equal intervals in the circumferential direction of the valve seat member 166.

[0130] The valve seat member 166 has a seal groove 271 formed at the axial center of the outer circumference of the main body portion 247. The seal groove 271 is annular and recessed radially inward from the outer surface of the main body portion 247. An O-ring 165 is placed within this seal groove 271.

[0131] The valve seat member 166 is fitted to the outer cylindrical portion 193 of the cap member 178 at its outer circumference, with its inner seat portion 241 and valve seat portion 242 facing away from the bottom portion 191 of the cap member 178. In this state, the O-ring 165 seals the gap between the outer cylindrical portion 193 of the cap member 178 and the valve seat member 166.

[0132] The cap member 178, O-ring 165, and valve seat member 166 form a cap chamber 285 inside the cap member 178. The cap chamber 285 is located between the bottom 191 of the cap member 178 and the valve seat member 166. The valve member 167, discs 168, 170, 172, 173, 174, 176, spring member 169, and disc spring 177 are located within this cap chamber 285. The valve seat member 166 has its valve seat portion 245 positioned on the cap chamber 285 side.

[0133] A first chamber communication chamber 286 for storing oil liquid L is formed within the cap chamber 285. The first chamber communication chamber 286 is formed by being surrounded by a cap member 178, a disc spring 177, a disc 174, a disc 173, a disc 172, a disc 170, a spring member 169, a disc 168, a valve member 167, and a valve seat member 166.

[0134] A second chamber communication chamber 287 for storing oil liquid L is formed within the cap chamber 285. The second chamber communication chamber 287 is formed by being surrounded by disc 173, disc 174, disc spring 177, and disc 176. The first chamber communication chamber 286 is the part of the cap chamber 285 excluding the second chamber communication chamber 287. The second chamber communication chamber 287 communicates with a passage in the passage hole 205 of the disc spring 177, and the passage in the passage hole 205 communicates with passages in a plurality of communication holes 195 in the bottom 191 of the cap member 178.

[0135] The communication between the first chamber 286 and the second chamber 287 is blocked by a disc spring 177, a disk 174 that abuts against the outer edge of the disc spring 177, and a disk 173 that abuts against the disk 174.

[0136] As shown in Figure 3, the annular valve seat member 166 and the bottomed cylindrical cap member 178 are positioned in the second chamber 23, which is one of the two chambers 23, the first chamber 22. In this case, the valve seat portion 242 of the valve seat member 166 is positioned on the second chamber 23 side.

[0137] The fixing member 182 is annular in shape and has the form shown in Figures 7 to 10. As shown in Figures 7 to 9, the fixing member 182 has a stopper portion 501 and a nut portion 502. As shown in Figures 8 and 9, the stopper portion 501 is on one side of the fixing member 182 in the axial direction, and the nut portion 502 is on the other side of the fixing member 182 in the axial direction. The fixing member 182 is a single metal part in which the stopper portion 501 and the nut portion 502 are formed seamlessly as one piece.

[0138] The stopper portion 501 has a cylindrical outer surface 501a. As shown in Figure 8, the stopper portion 501 has an insertion hole 511 in the radial center that is aligned with the axial direction. The stopper portion 501 has a contact surface 501b and a flow path 512 at the end opposite to the nut portion 502 in the axial direction.

[0139] The contact surface 501b is located on the opposite side of the nut portion 502 in the axial direction of the stopper portion 501 and is planar in shape, extending in a direction perpendicular to the axis of the stopper portion 501.

[0140] The flow path 512 is recessed from the contact surface 501b toward the nut portion 502 in the axial direction of the stopper portion 501. As shown in Figure 10, the flow path 512 has one circumferential flow path portion 515 and multiple radial flow path portions 516.

[0141] The circumferential flow channel 515 is formed in a coaxial, annular shape between the outer circumferential surface 501a of the stopper portion 501 and the insertion hole 511. The distance from the center of the stopper portion 501 in the radial direction to the center of the groove width of the circumferential flow channel 515 is approximately equal to the distance from the center of the cap member 178 in the radial direction to the center of the communication hole 195.

[0142] The radial flow channel section 516 extends radially outward from the circumferential flow channel section 515 to the stopper section 501. One end of the radial flow channel section 516, on the radial side of the stopper section 501, opens to the circumferential flow channel section 515, and the other end, on the radial side of the stopper section 501, opens to the outer circumferential surface 501a of the stopper section 501. Multiple radial flow channel sections 516 (specifically, eight locations) are formed in the stopper section 501. The multiple radial flow channel sections 516 are arranged at equal intervals in the circumferential direction of the stopper section 501. The number of radial flow channel sections 516 can be selected as any number. The flow channel 512 provided in the stopper section 501 has multiple radial flow channel sections 516 arranged radially toward the outside of the stopper section 501.

[0143] As shown in Figure 8, the portion between the circumferential flow channel 515 and the insertion hole 511 is an inner projection 521 that protrudes from the bottom surface of the circumferential flow channel 515 on the opposite side of the nut portion 502 in the axial direction of the stopper portion 501. The inner projection 521 is annular, as shown in Figure 10. Between adjacent radial flow channel sections 516 in the circumferential direction of the stopper portion 501, as shown in Figure 8, there is an outer projection 522 that protrudes from the bottom surface of the circumferential flow channel 515 and the bottom surface of the radial flow channel section 516 on the opposite side of the nut portion 502 in the axial direction of the stopper portion 501. As shown in Figure 10, the stopper portion 501 has the same number of outer projections 522 as the radial flow channel sections 516 (specifically, 8 locations). The multiple outer projections 522 are arranged at equal intervals in the circumferential direction of the stopper portion 501.

[0144] The aforementioned contact surface 501b is provided flush with the end of the inner projection 521 that is opposite to the nut portion 502 in the axial direction of the stopper portion 501, and with the end of the multiple outer projections 522 that is opposite to the nut portion 502 in the axial direction of the stopper portion 501.

[0145] As shown in Figure 9, the nut portion 502 has a tool engagement portion 531 and an anti-loosening portion 532. As shown in Figure 8, the nut portion 502 has a screw hole 533 with an internal thread 534 formed on its inner circumference. The screw hole 533 is located in the radial center of the nut portion 502 and is aligned with the axial direction of the nut portion 502. The screw hole 533 is slightly smaller in diameter than the insertion hole 511 and communicates with the insertion hole 511. The screw hole 533 and the insertion hole 511 constitute a through hole 535 that penetrates the fixing member 182 in the axial direction.

[0146] The tool engagement portion 531 is provided on the axial side of the nut portion 502 towards the stopper portion 501, and the anti-loosening portion 532 is provided on the axial side of the nut portion 502 away from the stopper portion 501. In other words, the fixing member 182 has the anti-loosening portion 532 positioned at the end of the nut portion 502.

[0147] As shown in Figure 7, the tool engagement portion 531 has a hexagonal outer surface 531a when viewed in the axial direction, and its maximum outer diameter is smaller than the outer diameter of the stopper portion 501. Before being assembled to the piston rod 31, the anti-loosening portion 532 is cylindrical, and its outer diameter is smaller than the minimum outer diameter of the tool engagement portion 531. As shown in Figure 8, the screw hole 533 is formed across both the tool engagement portion 531 and the anti-loosening portion 532.

[0148] In the stopper portion 501, the multiple radial flow channels 516 shown in Figure 10 are arranged such that two of the radial flow channels 516 are aligned in phase with a pair of diagonal positions on the outer circumferential surface 531a of the tool engagement portion 531 when the fixing member 182 is viewed in the axial direction. Furthermore, in the multiple radial flow channels 516, two of the radial flow channels 516 are arranged in phase with two sides parallel to the diagonal line connecting the aforementioned diagonal positions when the fixing member 182 is viewed in the axial direction.

[0149] While inserting the mounting shaft portion 33 of the piston rod 31 shown in Figure 3 inward, the annular member 125, disc 124, disc 123, multiple discs 122, disc 121, piston 21, disc 141, multiple discs 142, disc 143, disc 144, disc 160 shown in Figure 4, spring member 161, multiple discs 162, valve member 163, valve seat member 166 with O-ring 165 attached, valve member 167, multiple discs 168, spring member 169, disc 170, disc 172, disc 173, disc 174, disc 176, disc spring 177, and cap member 178 are stacked on the main shaft portion 32 of the piston rod 31 in this order. In this state, as shown in Figure 3, the fixing member 182 is screwed onto the male thread 57 of the screw shaft portion 44 that protrudes beyond the cap member 178 of the piston rod 31, with the stopper portion 501 facing the cap member 178. At this time, the fixing member 182 is screwed onto the screw shaft portion 44 using a tool engaged with the tool engagement portion 531 and tightened to a predetermined tightening torque. As a result, the nut portion 502 of the fixing member 182 is fixed to the piston rod 31, and the parts from the annular member 125 to the cap member 178 are clamped axially at least radially inward by the main shaft portion 32 and the fixing member 182. In this way, the first damping force generating mechanisms 85, 86 and the second damping force generating mechanism 140 including the cap member 178 are fixed to the piston rod 31 by the fixing member 182.

[0150] In this state, as shown in Figure 4, the fixing member 182 has a contact surface 501b of the stopper portion 501 that contacts the end surface 191a of the bottom portion 191 of the cap member 178 opposite to the axial outer cylindrical portion 193. Also in this state, as shown in Figure 3, the fixing member 182 has a portion of the tip cylindrical portion 43 of the piston rod 31 fitted into the insertion hole 511 and a portion of the screw shaft portion 44 inserted into it. The fixing member 182 is positioned radially relative to the piston rod 31 by fitting the tip cylindrical portion 43 of the piston rod 31 into the insertion hole 511. Furthermore, in this state, as shown in Figure 4, the circumferential flow path portion 515 of the stopper portion 501 of the fixing member 182 faces the communication hole 195 provided on the end face 191a of the bottom portion 191 of the cap member 178 opposite to the axial outer cylindrical portion 193, and thus the flow path 512 of the stopper portion 501 communicates with the communication hole 195. Since the fixing member 182 is positioned in the second chamber 23, the flow path 512 communicates with the second chamber 23 in multiple radial flow path portions 516, and as a result, the communication hole 195 communicates with the second chamber 23 via the flow path 512.

[0151] After the fixing member 182 is tightened to the piston rod 31, the anti-loosening portion 532 shown in Figure 3 is crimped radially inward and plastically deformed, causing deformation of the female thread 534 formed in the anti-loosening portion 532 and the male thread 57 of the piston rod 31. As a result, the fixing member 182 is prevented from loosening relative to the piston rod 31, i.e., its rotation is restricted.

[0152] As shown in Figure 4, the passage within the communication hole 195 of the cap member 178 is constantly in communication with the second chamber 23 via the flow path 512 of the fixing member 182. Therefore, the second chamber communication chamber 287 communicates with the second chamber 23 using the communication hole 195 as an orifice.

[0153] The first chamber communication chamber 286 is in constant communication with the first chamber 22 via the passage 288 in the communication groove 263 of the valve seat member 166, the intermediate chamber 237 in the second inner circumferential wall 233, the axial passage 54 of the piston rod 31, and the piston internal passage 103 and piston passage 81 provided in the piston 21 shown in Figure 3.

[0154] As the disk 174 shown in Figure 4 flexes in the axial direction, the volumes of the first chamber communication chamber 286 and the second chamber communication chamber 287 change. The second chamber communication chamber 287 decreases in volume to absorb the increase in volume of the first chamber communication chamber 286, and discharges the oil liquid L into the second chamber 23. The second chamber communication chamber 287 increases in volume to absorb the decrease in volume of the first chamber communication chamber 286, and allows the oil liquid L to flow in from the second chamber 23. Conversely, the first chamber communication chamber 286 decreases in volume to absorb the increase in volume of the second chamber communication chamber 287, and discharges the oil liquid L to the first chamber 22 side shown in Figure 3. The first chamber communication chamber 286 increases in volume to absorb the decrease in volume of the second chamber communication chamber 287, and allows the oil liquid L to flow in from the first chamber 22 side. As described above, the deformation of the disk 174 is suppressed from being inhibited by the oil liquid L in the first chamber communication chamber 286 and the second chamber communication chamber 287.

[0155] As shown in Figure 3, the multiple passages 282 of the valve seat member 166 are provided facing the second chamber 23 and are in constant communication with the second chamber 23.

[0156] The valve member 167 shown in Figure 4 is flexible. The valve member 167 has an outer diameter equivalent to the outer diameter of the valve seat portion 245 of the valve seat member 166. The valve member 167 is always in contact with the inner seat portion 244 and can seat on and off the valve seat portion 245. By seating on the entire valve seat portion 245, the valve member 167 closes all passage portions 282. Furthermore, by separating the valve member 167 from any of the valve seat components 265 of the valve seat portion 245, the valve member 167 opens the passage portion 282 inside the separated valve seat component 265.

[0157] The spring member 169 biases the valve member 167 to contact the valve seat portion 245 of the valve seat member 166. The valve member 167 seats on the valve seat portion 245 due to the biasing force of the spring member 169, closing the passage portion 282. The valve member 167 deforms against the biasing force of the spring member 169 and separates from the valve seat portion 245, thereby opening the passage portion 282.

[0158] When the valve member 167 moves away from the valve seat portion 245, it connects the multiple passage portions 282 with the first chamber communication chamber 286. As a result, the second chamber 23 communicates with the first chamber 22 via the multiple passage portions 282, the first chamber communication chamber 286, the passage 288 in the communication groove 263 of the valve seat member 166 and the intermediate chamber 237 in the second inner circumferential wall 233, the axial passage 54 of the piston rod 31, and the piston internal passage 103 and piston passage 81 provided in the piston 21 shown in Figure 3. At this time, the valve member 167 shown in Figure 4 suppresses the flow of oil L between itself and the valve seat portion 245, thereby generating a damping force.

[0159] The valve member 167 is an inlet valve that opens when oil liquid L flows in from the second chamber 23 to the first chamber communication chamber 286 side via a plurality of passage portions 282. The valve member 167 is a check valve that restricts the outflow of oil liquid L from the first chamber communication chamber 286 to the second chamber 23 via the passage portion 282. Here, the passage portion 281 opens outward from the range of the valve seat portion 245 of the valve seat member 166. For this reason, the passage portion 281 is always in communication with the first chamber communication chamber 286, independently of the valve member 167 which is seated on the valve seat portion 245.

[0160] The second passage 291 is comprised of multiple passage sections 282, the passage between the valve member 167 and the valve seat section 245 that appear when the valve is opened, the first chamber communication chamber 286, the passage 288 in the communication groove 263, the intermediate chamber 237, the axial passage 54, the piston internal passage 103 shown in Figure 3, and the piston passage 81. The second passage 291 is opened and closed by the valve member 167 shown in Figure 4. The second passage 291 allows oil liquid L to flow out from the second chamber 23, which is the upstream area in the cylinder 4, to the first chamber 22, which is the downstream area, as the piston 21 moves toward the second chamber 23. The second passage 291 is the compression-side passage through which oil liquid L flows from the second chamber 23, which is the upstream area, toward the first chamber 22, which is the downstream area, as the piston 21 moves toward the second chamber 23, that is, during the compression stroke. The second passage 291 on the contraction side is provided in parallel to the first passage 132 on the contraction side shown in Figure 3, at least in part, and in this case entirely. The second passage 291 includes the first chamber-side flow path 156.

[0161] As shown in Figure 4, the flow path 512, the passage in the communication hole 195, the passage in the passage hole 205, and the second chamber communication chamber 287 constitute the second chamber communication flow path 292. The second chamber communication flow path 292 is a contraction-side flow path that is always in communication with the second chamber 23. The contraction-side second chamber communication flow path 292 is provided separately from the second passage 291, which is also on the contraction side. The second chamber communication flow path 292 is provided in parallel with the second passage 291.

[0162] The valve member 167, the valve seat member 166 including the valve seat portion 245, the disc 168, and the spring member 169 constitute the sub-valve mechanism 301 (for example, the first sub-valve). The sub-valve mechanism 301 is provided in the compression-side second passage 291. The sub-valve mechanism 301 opens and closes this second passage 291, suppressing the flow of oil L from this second passage 291 to the first chamber 22 and generating a damping force. The sub-valve mechanism 301 is a valve mechanism on the compression side. The second damping force generating mechanism 140 is provided in the second passage 291 formed in the valve seat member 166 where the sub-valve mechanism 301 is located, and generates a damping force by opening and closing the second passage 291.

[0163] The sub-valve mechanism 301 includes a valve seat portion 245 which is a valve seat and a valve member 167 which is a flexible valve body, and is a check valve mechanism that allows flow in the second passage 291 from the second chamber 23 which is the upstream region during the compression stroke toward the first chamber 22 which is the downstream region, while restricting flow in the direction from the first chamber 22 which is the upstream region during the extension stroke toward the second chamber 23 which is the downstream region. In other words, the sub-valve mechanism 301 only allows flow in the second passage 291 from the second chamber 23 which is the upstream region during the compression stroke toward the first chamber 22 which is the downstream region.

[0164] The sub-valve mechanism 301 has its valve seat portion 245 provided on the valve seat member 166. The sub-valve mechanism 301 is arranged separately from the first damping force generating mechanism 86, which generates damping force in the same compression stroke. The valve member 167 that constitutes the compression-side sub-valve mechanism 301 is the compression-side sub-valve.

[0165] In the compression-side sub-valve mechanism 301, neither the valve seat portion 245 nor the valve member 167 that abuts it has a fixed orifice that connects the first chamber 22 and the second chamber 23 even when the valve seat portion 245 and the valve member 167 are in contact. In other words, the second passage 291 does not have a fixed orifice that constantly connects the first chamber 22 and the second chamber 23. The second passage 291 is not a passage that constantly connects the first chamber 22 and the second chamber 23.

[0166] The second compression-side passage 291, which connects the first chamber 22 and the second chamber 23, is in parallel with the first compression-side passage 132, which also connects the first chamber 22 and the second chamber 23. The first damping force generating mechanism 86 is provided in the first passage 132. The sub-valve mechanism 301 is provided in the second passage 291. Therefore, both the first damping force generating mechanism 86 and the sub-valve mechanism 301, which are on the compression side, are arranged in parallel.

[0167] The valve member 163 is flexible. The valve member 163 has an outer diameter equivalent to the outer diameter of the valve seat portion 242 of the valve seat member 166. The valve member 163 is always in contact with the inner seat portion 241 and can seat on and off the valve seat portion 242. When the valve member 163 seats on the entire valve seat portion 242, it closes all passage portions 281. Also, when the valve member 163 separates from any of the valve seat components 255 of the valve seat portion 242, it opens the passage portion 281 inside the separated valve seat component 255.

[0168] The outer diameter of the disc 162 is smaller than the outer diameter of the valve member 163 and smaller than the outer diameter of the inner seat portion 241. The spring member 161 is flexible. The spring member 161 has a base plate portion 311 and a plurality of spring plate portions 312.

[0169] The base plate 311 is a perforated circular flat plate. The mounting shaft 33 is fitted into the inner circumference of the base plate 311. The outer diameter of the base plate 311 is slightly larger than the outer diameter of the disk 162. The base plate 311 is in contact with the disk 162.

[0170] Multiple spring plate portions 312 extend radially from the outer peripheral edge of the substrate portion 311. The further outward the multiple spring plate portions 312 are from the substrate portion 311 in the axial direction, the further they are from the substrate portion 311 in the radial direction.

[0171] The spring member 161 has a maximum outer diameter smaller than the outer diameter of the valve member 163. The spring member 161 has multiple spring plate portions 312 that extend from the base portion 311 toward the valve member 163 in the axial direction of the base portion 311. The extended ends of the multiple spring plate portions 312 of the spring member 161 are pressed against the outer circumference of the valve member 163. As a result, the multiple spring plate portions 312 of the spring member 161 bias the outer circumference of the valve member 163 so that it abuts against the valve seat portion 242 of the valve seat member 166. The valve member 163 seats on the valve seat portion 242 due to the biasing force of the spring member 161 and closes the passage portion 281. The valve member 163 deforms against the biasing force of the spring member 161 and separates from the valve seat portion 242, opening the passage portion 281.

[0172] The valve member 163 is located within the second chamber 23. By moving away from the valve seat portion 242, the valve member 163 connects the first chamber communication chamber 286 and the second chamber 23 via multiple passage portions 281 of the valve seat member 166. At this time, the valve member 163 suppresses the flow of oil L between itself and the valve seat portion 242, thereby generating a damping force. The valve member 163 is a discharge valve that opens when oil L is discharged from the first chamber communication chamber 286 to the second chamber 23 via multiple passage portions 281. The valve member 163 is a check valve that restricts the inflow of oil L from the second chamber 23 into the first chamber communication chamber 286 via the passage portions 281. Here, the passage portions 282 open outward from the range of the valve seat portion 242 in the valve seat member 166. Therefore, the passage portion 282 is always in communication with the second chamber 23, independently of the valve member 163 that sits on the valve seat portion 242.

[0173] The radial communication groove 253 formed in the inner seat portion 241 of the valve seat member 166 serves as a radial flow path 317. The radial flow path 317 is located in the radial direction of the valve seat member 166 opposite the axial flow path 54 and communicates with the intermediate chamber 237.

[0174] As shown in Figure 3, the second passage 315 consists of a first chamber-side passage 156 comprising a piston passage 81 and a piston internal passage 103, an axial passage 54 of the piston rod 31, an intermediate chamber 237 and passage 288 within the second inner circumferential wall 233 of the valve seat member 166, a first chamber communication chamber 286, a passage portion 281, a radial passage 317 as shown in Figure 4, and a passage between the valve member 163 and the valve seat portion 242 that appears when the valve is opened.

[0175] The second passage 315 is opened and closed by the valve member 163. The second passage 315 allows oil L to flow from the first chamber 22, which is the upstream side of the cylinder 4, to the second chamber 23, which is the downstream side, as the piston 21 moves toward the first chamber 22 side as shown in Figure 3. The second passage 315 is the extension-side passage through which oil L flows from the first chamber 22, which is the upstream side, toward the second chamber 23, which is the downstream side, as the piston 21 moves toward the first chamber 22 side, that is, during the extension stroke. The extension-side second passage 315 is provided in parallel with the extension-side first passage 152, at least in part, in this case, in part. The second passage 315 is parallel to the first passage 152, except for a portion on the first chamber 22 side of the piston passage 81's internal piston flow path 103.

[0176] The radial flow path 317 shown in Figure 4 connects the intermediate chamber 237 and the passage section 281 of the second passage 315 without going through the passage 288 and the first chamber connecting chamber 286 in the connecting groove 263. The radial flow path 317 communicates from the intermediate chamber 237 to the valve seat section 242. In other words, the radial flow path 317 communicates from the central hole 231 to the sub-valve mechanism 321 including the valve seat section 242.

[0177] As shown in Figure 3, the piston rod 31 has an axial passage 54 which is a passage that communicates with the first chamber side passage 156 and is directed toward the second chamber 23 which is the downstream region during the extension stroke, a circumferential groove 53 which is a circumferential groove provided at the end of the axial passage 54 on the second chamber 23 side which is the downstream region during the extension stroke, and a cylindrical portion 43 which is a cylindrical part provided on the second chamber 23 side of the circumferential groove 53.

[0178] As shown in Figure 4, the outer diameter of the disc 160 is the same as the outer diameter of the valve member 163. The disc 160 is flexible.

[0179] The valve member 163, the valve seat member 166 including the valve seat portion 242, the disc 162, and the spring member 161 constitute the sub-valve mechanism 321 (for example, the second sub-valve). The sub-valve mechanism 321 is provided in the extension-side second passage 315 and opens and closes this second passage 315. The sub-valve mechanism 321 generates a damping force by suppressing the flow of oil L from the second passage 315 to the second chamber 23. The sub-valve mechanism 321 is an extension-side valve mechanism. The second damping force generating mechanism 140 is provided in the second passage 315 formed in the valve seat member 166 where the sub-valve mechanism 321 is located, and generates a damping force by opening and closing the second passage 315. The sub-valve mechanism 321 is arranged separately from the first damping force generating mechanism 85 which generates a damping force in the same extension stroke. The valve member 163 that constitutes the extension-side sub-valve mechanism 321 is an extension-side sub-valve. The sub-valve mechanism 321 includes a radial flow path 317. During the extension stroke, the oil L flows from the first chamber-side flow path 156 shown in Figure 3 to the second chamber 23, which is the downstream region, via the axial flow path 54 including the tip-side circumferential groove 53, the intermediate chamber 237, and the radial flow path 317 shown in Figure 4. In other words, during the extension stroke, the oil L flows from the first chamber-side flow path 156 to the second chamber 23, which is the downstream region, via the axial flow path 54 including the tip-side circumferential groove 53, the central hole 231, and the radial flow path 317.

[0180] The extension-side second passage 315, which connects the second chamber 23 and the first chamber 22, is in parallel with the extension-side first passage 152, which also connects the second chamber 23 and the first chamber 22. The first damping force generating mechanism 85 is provided in the first passage 152. The sub-valve mechanism 321 is provided in the second passage 315. Therefore, both the compression-side first damping force generating mechanism 85 and the sub-valve mechanism 321 are arranged in parallel.

[0181] Sub-valve mechanism 301 is provided on one side of the portion of the valve seat member 166 of the second passage 291, and sub-valve mechanism 321 is provided on the other side of the portion of the valve seat member 166 of the second passage 291. Sub-valve mechanism 321 is provided on one side of the portion of the valve seat member 166 of the second passage 315, and sub-valve mechanism 301 is provided on the other side of the portion of the valve seat member 166 of the second passage 315.

[0182] The sub-valve mechanism 321 includes a valve seat portion 242 which is a valve seat and a valve member 163 which is a flexible valve body. It is a check valve mechanism that allows flow from the first chamber 22, which is the upstream region, to the second chamber 23, which is the downstream region, during the extension stroke of the second passage 315, which includes the first chamber-side flow path 156, while restricting flow from the second chamber 23, which is the upstream region, to the first chamber 22, which is the downstream region, during the contraction stroke. In other words, the sub-valve mechanism 321 only allows flow from the first chamber 22, which is the upstream region, to the second chamber 23, which is the downstream region, during the extension stroke of the second passage 315, which includes the first chamber-side flow path 156.

[0183] The second chamber communication chamber 287 and the discs 174, 173, disc spring 177, and 176 that form it constitute a second chamber volume variable mechanism 325 that can change the volume of the second chamber communication chamber 287.

[0184] The second chamber volume variable mechanism 325 causes disks 174 and 173 to deform and move together so that they move away from the bottom 191. Then, the second chamber volume variable mechanism 325 changes its configuration to increase the volume of the second chamber communication chamber 287. At this time, if disk 174 maintains contact with the disc spring 177 around its entire circumference, the space between it and the outer tapered portion 202 of the disc spring 177 is closed. In other words, as disk 174 deforms to move away from the bottom 191, if it maintains contact with the disc spring 177 around its entire circumference, the separation between the second chamber communication chamber 287 and the first chamber communication chamber 286 is maintained.

[0185] Furthermore, the second chamber volume variable mechanism 325 deforms and moves the discs 174 and 173 together so that they move closer to the bottom 191. As a result, the second chamber volume variable mechanism 325 changes its configuration to reduce the volume of the second chamber communication chamber 287. At this time, the disc 174 maintains a state in which it is in contact with the disc spring 177 as a whole, and the space between it and the outer tapered portion 202 of the disc spring 177 is closed.

[0186] The first chamber communication chamber 286, which communicates with the first chamber 22, constitutes a part of the extension-side second passage 315. The first chamber communication chamber 286, along with the valve seat member 166, valve member 167, disc 168, spring member 169, disc 170, disc 172, disc 173, disc 174, disc 176, disc spring 177, and cap member 178 that form it, constitute the first chamber volume variable mechanism 326, which can change the volume of the first chamber communication chamber 286.

[0187] The first chamber volume variable mechanism 326 deforms and moves disks 174 and 173 together so that they move away from disk 170. Then, the first chamber volume variable mechanism 326 changes to increase the volume of the first chamber communication chamber 286. At that time, if disk 173 is maintained in contact with disk 174 as a whole, it closes the passage in the through hole 211 of disk 174. That is, it maintains the blocked state between the second chamber communication chamber 287 and the first chamber communication chamber 286.

[0188] Furthermore, the first chamber volume variable mechanism 326 deforms and moves disks 174 and 173 so that they move closer to disk 170. As a result, the first chamber volume variable mechanism 326 changes its configuration to reduce the volume of the first chamber communication chamber 286. At this time, disk 173 maintains a state in which it is in contact with disk 174 as a whole, thereby blocking the passage in the through hole 211 of disk 174.

[0189] In the extension-side sub-valve mechanism 321, neither the valve seat portion 242 nor the valve member 163 that abuts it has a fixed orifice that connects the first chamber 22 and the second chamber 23 even when the valve seat portion 242 and the valve member 163 are in contact. In other words, the extension-side sub-valve mechanism 321 does not connect the first chamber 22 and the second chamber 23 when the valve seat portion 242 and the valve member 163 are in contact. To put it another way, the second passage 315 is not provided with a fixed orifice that constantly connects the first chamber 22 and the second chamber 23. The second passage 315 is not a passage that constantly connects the first chamber 22 and the second chamber 23.

[0190] The spring member 161, disc 162, valve member 163, O-ring 165, valve seat member 166, valve member 167, disc 168, spring member 169, disc 170, disc 172, disc 173, disc 174, disc 176, disc spring 177, and cap member 178 constitute the second structural member 331.

[0191] Therefore, the second structural member 331 has a first inner circumferential wall 232 that penetrates the center axially and through which the piston rod 31 is inserted, and a second inner circumferential wall 233 that is radially spaced further away from the piston rod 31 than the first inner circumferential wall 232, and has a central hole 231 that communicates directly or indirectly with the circumferential groove 53 on the tip side of the piston rod 31. The second structural member 331 also includes a valve seat portion 242 which is a valve seat, and a valve member 163 which is a flexible valve body, and has a sub-valve mechanism 321 that allows the flow in the first chamber side passage 156 to be only in the direction from the first chamber 22 to the second chamber 23. The second structural member 331 also has a sub-valve mechanism 301 and a sub-valve mechanism 321. Furthermore, the second structural member 331 has a cap member 178 that communicates with an intermediate chamber 237 formed by the second inner circumferential wall 233 and the piston rod 31, and forms a first chamber communicating chamber 286 for storing the oil liquid L. The second structural member 331 also has a sub-valve mechanism 321 that includes a central hole 231 through which the piston rod 31 is inserted, a valve seat portion 242 which is a valve seat, and a valve member 163 which is a flexible valve body disposed in the axial flow path 54, and allows flow of the oil liquid L only in the direction from the first chamber 22 to the second chamber 23. The second structural member 331 also has a radial flow path 317 that is provided at a position opposite to the axial flow path 54 and communicates with the sub-valve mechanism 321. Furthermore, the second structural member 331 has one or more expansion portions 235 that extend radially from the insertion hole 234 and are formed from the surface opposite to the surface facing the first structural member 155 to a position that communicates with the axial flow path 54, a cap member 178 that communicates with the expansion portion 235 and forms a first chamber communication chamber 286 for storing the oil liquid L, and a passage portion 281 that connects the first chamber communication chamber 286 and the sub-valve mechanism 321.

[0192] As shown in Figure 3, the second structural member 331 has an outer diameter smaller than the outer diameter of the first structural member 155. The second structural member 331 has a radial gap between it and the inner cylinder 2. The second structural member 331 extends over the circumferential groove 53 and the cylindrical portion 43 at the tip of the piston rod 31.

[0193] As described above, the first chamber volume variable mechanism 326 shown in Figure 4 changes the volume of the first chamber communication chamber 286 by deforming and moving the disk 174 so that it moves away from the disk 170. At that time, with the sub-valve mechanism 321 open, the pressure difference between the first chamber communication chamber 286 and the second chamber communication chamber 287 may exceed a predetermined value. In that case, the first chamber volume variable mechanism 326 causes the disk 174 to deform towards the bottom 191 side, while the outer tapered portion 202 of the disc spring 177 elastically deforms towards the bottom 191 side. As a result, the disk 174 moves axially away from the disk 173. Then, the disk 174 connects the first chamber communication chamber 286 and the second chamber communication chamber 287 through the passage in the through hole 211.

[0194] Disks 174 and 173 constitute the relief mechanism 335. When the valve is open, the relief mechanism 335 allows oil liquid L to flow from the first chamber communication chamber 286 to the second chamber communication chamber 287. In other words, the relief mechanism 335 allows oil liquid L to flow from the first chamber 22 to the second chamber 23. The relief mechanism 335 is an extension-side relief mechanism. The relief mechanism 335 is set to open after the extension-side sub-valve mechanism 321 has opened.

[0195] The second chamber volume variable mechanism 325 changes the configuration so that the disk 174 deforms and moves closer to the disk 170, thereby increasing the volume of the second chamber communication chamber 287. At this time, with the sub-valve mechanism 301 open, the pressure difference between the first chamber communication chamber 286 and the second chamber communication chamber 287 may exceed a predetermined value. In this case, the second chamber volume variable mechanism 325 increases the amount of deformation on the outer circumference of the disk 174. As a result, the disk 174 moves axially away from the outer circumference of the disc spring 177. Then, the disk 174 connects the second chamber communication chamber 287 and the first chamber communication chamber 286 through the disc spring 177.

[0196] The disc 174 and the disc spring 177 constitute the relief mechanism 336. When the valve is open, the relief mechanism 336 allows oil liquid L to flow from the second chamber communication chamber 287 to the first chamber communication chamber 286. In other words, the relief mechanism 336 allows oil liquid L to flow from the second chamber 23 to the first chamber 22. The relief mechanism 336 is a relief mechanism for the compression side. The relief mechanism 336 is set to open after the compression side sub-valve mechanism 301 has opened.

[0197] As shown in Figure 1, the base valve 15 has a valve mechanism 351 on the axial bottom 9 side of the valve body 12. The base valve 15 also has a valve mechanism 352 on the side opposite to the axial bottom 9 of the valve body 12.

[0198] When the piston rod 31 moves in the compression direction and the piston 21 moves in a direction that narrows the second chamber 23, and the pressure in the second chamber 23 becomes higher than the pressure in the reservoir chamber 5 by a predetermined value or more, the base valve 15 opens its valve mechanism 351, allowing the oil L from the second chamber 23 to flow into the reservoir chamber 5. The valve mechanism 351 generates a damping force at this time.

[0199] When the piston rod 31 moves in the extension direction and the piston 21 moves toward the first chamber 22, and the pressure in the second chamber 23 falls below the pressure in the reservoir chamber 5, the base valve 15 opens, and the valve mechanism 352 opens, allowing the oil L from the reservoir chamber 5 to flow into the second chamber 23. At this time, the valve mechanism 352 generates a damping force. The valve mechanism 352 may also be a suction valve that flows the oil L from the reservoir chamber 5 into the second chamber 23 without substantially generating a damping force.

[0200] "Regarding the operation of the shock absorber" Next, we will explain the operation of buffer 1. As shown in Figure 3, of the first damping force generating mechanism 85 and the sub-valve mechanism 321, both on the extension side, the valve member 151 of the first damping force generating mechanism 85 has higher rigidity and a higher opening pressure than the valve member 163 of the sub-valve mechanism 321 shown in Figure 4. Therefore, in the extension stroke, in the extremely low-speed region where the piston speed is lower than a predetermined value, the first damping force generating mechanism 85 shown in Figure 3 remains closed while the sub-valve mechanism 321 opens. In other words, the sub-valve mechanism 321 opens and generates damping force when the piston speed is lower than that of the first damping force generating mechanism 85. Furthermore, in the normal speed region where the piston speed is above this predetermined value, both the first damping force generating mechanism 85 and the sub-valve mechanism 321 open. The valve member 163 shown in Figure 4 is an extremely low-speed valve that deforms against the biasing force of the spring member 161 in the extremely low-speed region of the piston speed, opens, and generates damping force.

[0201] In other words, during the extension stroke, the piston 21 shown in Figure 3 moves toward the first chamber 22, increasing the pressure in the first chamber 22 and decreasing the pressure in the second chamber 23. Here, neither the first damping force generating mechanisms 85, 86 nor the sub-valve mechanisms 301, 321 have a fixed orifice that keeps the first chamber 22 and the second chamber 23 in constant communication. Therefore, the oil L in the first chamber 22 flows into the first chamber communication chamber 286 via the first chamber side passage 156 of the piston 21, the axial passage 54 of the piston rod 31, and the intermediate chamber 237 and passage 288 of the valve seat member 166. As a result, the pressure in the first chamber communication chamber 286 increases. Consequently, before the sub-valve mechanism 321 opens, the portion of the first chamber volume variable mechanism 326 radially inward from the contact position of the disc spring 177 with the outer tapered portion 202 of the disc 174 flexes toward the bottom 191. As a result, disk 174 increases the volume of the first chamber communication chamber 286. This allows the first chamber volume variable mechanism 326 to suppress the pressure rise in the first chamber communication chamber 286. At this time, disk 173 deforms in accordance with disk 174, maintaining the closed state of the passage in the through hole 211. Also, at this time, as disk 174 bends and moves toward the bottom 191, the second chamber volume variable mechanism 325 reduces the volume of the second chamber communication chamber 287.

[0202] Here, during the extension stroke when the shock absorber 1 is subjected to low-frequency input (large-amplitude excitation), the amount of oil L flowing from the first chamber 22 to the first chamber communication chamber 286 becomes large. As a result, the disk 174 deforms significantly. When the amount of deformation of the disk 174 becomes large, the reaction force due to the support rigidity of the clamped inner circumference side becomes large, limiting the amount of deformation. This causes the first chamber communication chamber 286 to become pressurized. As a result, the second passage 315 becomes pressurized to the point where the sub-valve mechanism 321 opens.

[0203] In this case, neither the first damping force generating mechanisms 85, 86 nor the sub-valve mechanisms 301, 321 have a fixed orifice that keeps the first chamber 22 and the second chamber 23 in constant communication. As a result, in the extension stroke when the piston speed is below the first predetermined value at which the sub-valve mechanism 321 opens, the damping force rises sharply. Furthermore, in the region where the piston speed is faster than the first predetermined value but slower than the second predetermined value, the first damping force generating mechanism 85 remains closed while the sub-valve mechanism 321 opens.

[0204] In other words, the valve member 163 deforms against the biasing force of the spring member 161 and separates from the valve seat portion 242. This causes the extension-side second passage 315 to connect the first chamber 22 and the second chamber 23. As a result, the oil L in the first chamber 22 flows into the second chamber 23 via the first chamber-side passage 156 of the piston 21, the axial passage 54 of the piston rod 31, the intermediate chamber 237, passage 288 and passage portion 281 of the valve seat member 166, and the passage between the valve member 163 and the valve seat portion 242. At the same time, the oil L in the first chamber 22 flows into the second chamber 23 via the first chamber-side passage 156, the axial passage 54, the intermediate chamber 237 and radial passage 317 of the valve seat member 166, and the passage between the valve member 163 and the valve seat portion 242. As a result, even in the extremely low-speed region where the piston speed is lower than the second predetermined value, a damping force conforming to valve characteristics (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained.

[0205] Furthermore, a relief mechanism 335 is provided that opens after the sub-valve mechanism 321 opens during the extension stroke. Therefore, in the normal speed range where the piston speed is above a second predetermined value, if the pressure in the first chamber communication chamber 286 increases, the relief mechanism 335 opens while the sub-valve mechanism 321 remains open, allowing the oil L from the first chamber communication chamber 286 to flow to the second chamber 23 via the second chamber communication chamber 287 and the second chamber communication passage 292. Subsequently, with the sub-valve mechanism 321 and the relief mechanism 335 remaining open, the first damping force generating mechanism 85 opens. That is, as described above, when the valve member 163 deforms against the biasing force of the spring member 161 and separates from the valve seat portion 242, the oil L flows from the first chamber 22 to the second chamber 23 in the extension-side second passage 315. Subsequently, with the sub-valve mechanism 321 still open, the relief mechanism 335 opens, allowing the oil liquid L to flow from the first chamber 22 to the second chamber 23 through the second chamber communication chamber 287 and the second chamber communication passage 292. At this time, the flow of the oil liquid L is restricted in the first chamber side passage 156 provided in the second passage 315. As a result, the pressure applied to the valve member 151 increases, the differential pressure increases, the valve member 151 separates from the valve seat portion 105, and the oil liquid L flows from the first chamber 22 to the second chamber 23 through the extension side first passage 152. Thus, the oil liquid L in the first chamber 22 flows to the second chamber 23 via the first passage 152, which consists of the piston passage 81 and the passage between the valve member 151 and the valve seat portion 105.

[0206] As a result, even in the normal speed range where the piston speed is above the second predetermined value, a damping force with valve characteristics (damping force is approximately proportional to piston speed) can be obtained. The rate of increase in the extension damping force with respect to an increase in piston speed in the normal speed range is lower than the rate of increase in the extension damping force with respect to an increase in piston speed in the extremely low speed range.

[0207] As described above, in the extension stroke, in the normal speed range where the piston speed is above the second predetermined value, the valve member 151 opens, allowing the oil liquid L to flow at a large flow rate through the first passage 152. As a result, the flow rate through the passage between the valve member 163 and the valve seat portion 242 is reduced. Therefore, for example, it is possible to reduce the rate of increase of damping force with respect to the increase in piston speed in the normal speed range (above the second predetermined value). This expands the design flexibility.

[0208] During the extension stroke when a higher frequency is input to the buffer 1 than during the low-frequency input described above (during small-amplitude excitation), the amount of oil L flowing from the first chamber 22 to the first chamber communication chamber 286 is small. As a result, the deformation of the disk 174 is small, and the variable first chamber volume mechanism 326 can absorb the volume of oil L flowing into the first chamber communication chamber 286 with the amount of deflection of the disk 174. Therefore, the pressure increase in the first chamber communication chamber 286 is small. As a result, during the rise of the extremely low-speed damping force, the situation is as if the disk 174 were not present. In other words, during the rise of the extremely low-speed damping force, it is possible to create a state in which the first chamber communication chamber 286 is constantly in communication with the second chamber 23 through the second chamber communication passage 292, that is, a state similar to a structure without the sub-valve mechanism 321.

[0209] Therefore, during the extension stroke at high-frequency input, the rise of the extremely low-speed damping force becomes gentler compared to low-frequency input or conventional damping force characteristics. In other words, during the extension stroke, when the frequency of the piston 21 exceeds a predetermined frequency, the first chamber volume variable mechanism 326, which includes the disc 174, limits the flow rate of the oil liquid L to the valve member 163 of the sub-valve mechanism 321. Furthermore, by adjusting the rigidity (plate thickness, etc.) of the disc 174, the change in damping force until the sub-valve mechanism 321 opens (the slope of the damping force with respect to piston speed) can be adjusted.

[0210] In both cases, the valve member 131 of the first damping force generating mechanism 86 and the sub-valve mechanism 301 on the compression side have higher rigidity and higher opening pressure than the valve member 167 of the sub-valve mechanism 301. Therefore, in the compression stroke, in the extremely low-speed region where the piston speed is lower than a predetermined value, the first damping force generating mechanism 86 remains closed while the sub-valve mechanism 301 opens. In other words, the sub-valve mechanism 301 opens and generates damping force when the piston speed is lower than that of the first damping force generating mechanism 86. In the normal speed region where the piston speed is above this predetermined value, both the first damping force generating mechanism 86 and the sub-valve mechanism 301 open. The valve member 167 is an extremely low-speed valve that opens and generates damping force in the extremely low-speed region of the piston speed.

[0211] In other words, during the compression stroke, the piston 21 moves toward the second chamber 23, increasing the pressure in the second chamber 23 and decreasing the pressure in the first chamber 22. Here, neither the first damping force generating mechanisms 85, 86 nor the sub-valve mechanisms 301, 321 have a fixed orifice that keeps the second chamber 23 and the first chamber 22 in constant communication. As a result, the oil L in the second chamber 23 flows into the second chamber communication chamber 287 via the second chamber communication passage 292. This causes the pressure in the second chamber communication chamber 287 to increase. Therefore, the disc 174 of the second chamber volume variable mechanism 325 bends toward the disc 170 before the sub-valve mechanism 301 opens. This causes the disc 174 to increase the volume of the second chamber communication chamber 287. As a result, the second chamber volume variable mechanism 325 suppresses the rise in pressure in the second chamber communication chamber 287. At this time, disk 173 deforms in accordance with disk 174, maintaining the closed state of the passage within the through hole 211. Also, as disk 174 bends and moves toward disk 170, the first chamber volume variable mechanism 326 reduces the volume of the first chamber communication chamber 286.

[0212] Here, during the compression stroke when the shock absorber 1 is subjected to low-frequency input (large-amplitude excitation), the amount of oil L flowing from the second chamber 23 to the second chamber connecting chamber 287 becomes large. As a result, the disk 174 deforms significantly. When the amount of deformation of the disk 174 becomes large, the reaction force due to the support rigidity on the clamped inner circumference side becomes large, limiting the amount of deformation. This causes the second chamber connecting chamber 287 to become pressurized. As a result, the second passage 291 becomes pressurized to the point where the sub-valve mechanism 301 opens.

[0213] In this case, neither the first damping force generating mechanisms 85, 86 nor the sub-valve mechanisms 301, 321 have a fixed orifice that keeps the second chamber 23 and the first chamber 22 in constant communication. As a result, during the compression stroke when the piston speed is below the third predetermined value at which the sub-valve mechanism 301 opens, the damping force rises rapidly. Furthermore, in the region where the piston speed is faster than the third predetermined value but slower than the fourth predetermined value, the first damping force generating mechanism 86 remains closed while the sub-valve mechanism 301 opens.

[0214] In other words, when the valve member 167 deforms against the biasing force of the spring member 169 and separates from the valve seat portion 245, the compression-side second passage 291 connects the second chamber 23 and the first chamber 22. As a result, the oil L in the second chamber 23 flows into the first chamber 22 via the passage portion 282 in the valve seat member 166, the passage between the valve member 167 and the valve seat portion 245, the first chamber connecting chamber 286, the passage 288 and intermediate chamber 237 of the valve seat member 166, the axial passage 54 of the piston rod 31, the first chamber side passage 156 of the piston 21, and the piston passage 81 of the piston 21. This allows the damping force of the valve characteristics (a characteristic in which the damping force is approximately proportional to the piston speed) to be obtained even in the extremely low-speed region where the piston speed is lower than the fourth predetermined value.

[0215] Furthermore, a relief mechanism 336 is provided that opens after the sub-valve mechanism 301 opens during the compression stroke. Therefore, in the normal speed range where the piston speed is above the fourth predetermined value, when the pressure in the second chamber communication chamber 287 increases, the relief mechanism 336 opens while the sub-valve mechanism 301 remains open, allowing the oil L from the second chamber 23 and the second chamber communication chamber 287 to flow to the first chamber 22 via the first chamber communication chamber 286. Subsequently, the first damping force generating mechanism 86 opens while the sub-valve mechanism 301 and the relief mechanism 336 remain open. In other words, as described above, when the valve member 167 separates from the valve seat portion 245, the oil L flows from the second chamber 23 to the first chamber 22 in the compression-side second passage 291. Subsequently, with the sub-valve mechanism 301 still open, the relief mechanism 336 opens, allowing the oil liquid L to flow from the second chamber 23 to the first chamber 22. At this time, the flow of the oil liquid L is restricted in the piston internal passage 103 located downstream of the valve member 167 and the relief mechanism 336 in the second passage 291. This increases the pressure applied to the valve member 131, increasing the differential pressure. As a result, the valve member 131 separates from the valve seat portion 115, allowing the oil liquid L to flow from the second chamber 23 to the first chamber 22 in the compression-side first passage 132. Therefore, the oil liquid L in the second chamber 23 flows into the first chamber 22 via the piston passage 82 and the passage between the valve member 131 and the valve seat portion 115.

[0216] As a result, even in the normal speed range where the piston speed is above the fourth predetermined value, a damping force with valve characteristics (damping force is approximately proportional to piston speed) can be obtained. The rate of increase in compression damping force with respect to an increase in piston speed in the normal speed range is lower than the rate of increase in compression damping force with respect to an increase in piston speed in the extremely low speed range.

[0217] As described above, in the compression stroke, in the normal speed range where the piston speed is above the fourth predetermined value, the valve member 131 opens, allowing the oil liquid L to flow at a large flow rate through the first passage 132. This reduces the flow rate through the passage between the valve member 167 and the valve seat portion 245. Therefore, for example, it is possible to reduce the rate of increase in damping force with respect to the increase in piston speed in the normal speed range (above the fourth predetermined value). This expands the design flexibility.

[0218] During the compression stroke when a higher frequency is input to the buffer 1 than during the low-frequency input described above (during small-amplitude excitation), the amount of oil L flowing from the second chamber 23 to the second chamber communication chamber 287 is small. Therefore, the deformation of the disk 174 is small. As a result, the variable volume second chamber mechanism 325 can absorb the volume of oil L flowing into the second chamber communication chamber 287 with the amount of deflection of the disk 174. Therefore, the pressure increase in the second chamber communication chamber 287 is small. For this reason, when the extremely low-speed damping force is rising, it is as if the disk 174 were not present. In other words, when the extremely low-speed damping force is rising, it is possible to create a state in which the second chamber communication chamber 287 is constantly in communication with the first chamber communication chamber 286, that is, a state as if the sub-valve mechanism 301 were not present.

[0219] Therefore, during the compression stroke at high frequency input, the rise of the extremely low-speed damping force becomes gentler compared to low-frequency input or conventional damping force characteristics. In other words, when the frequency of the piston 21 exceeds a predetermined frequency, the second chamber volume variable mechanism 325, which includes the disc 174, limits the flow rate of the oil liquid L to the valve member 167 of the sub-valve mechanism 301. Furthermore, the change in damping force until the sub-valve mechanism 301 opens (the slope of the damping force with respect to piston speed) can be adjusted by changing the rigidity (plate thickness, etc.) of the disc 174.

[0220] Patent Document 1, mentioned above, discloses a structure in which a cap member is fixed to a piston rod with an annular member and a nut in a shock absorber. However, there is a demand to reduce the number of parts in a shock absorber.

[0221] The shock absorber 1 of the first embodiment includes a first damping force generating mechanism 86 provided in a first passage 132 formed in the piston 21 and generating damping force, a first damping force generating mechanism 85 provided in a first passage 152 formed in the piston 21 and generating damping force, and a second damping force generating mechanism 140 provided in a second passage 291 parallel to the first passage 132 and a second passage 315 parallel to the first passage 152 and generating damping force. The second damping force generating mechanism 140 includes an annular valve seat member 166 arranged in the second chamber 23 of the first chamber 22 and the second chamber 23, a sub-valve mechanism 301 provided on one side of the second passages 291, 315 formed in the valve seat member 166 and a sub-valve mechanism 321 provided on the other side, and a bottomed cylindrical cap member 178 having an outer cylindrical portion 193 and a bottom portion 191, with a communication hole 195 provided in the bottom portion 191. Furthermore, the shock absorber 1 has a fixing member 182 that fixes the first damping force generating mechanisms 85, 86 and the second damping force generating mechanism 140 to the piston rod 31. This fixing member 182 has a stopper portion 501 that faces the cap member 178 and has a contact surface 501b that abuts against the cap member 178 and a flow path 512 that communicates with the communication hole 195, and a nut portion 502 that is fixed to the piston rod 31, with a loosening prevention portion 532 positioned at the end of the nut portion 502. In this way, the shock absorber 1 has a fixing member 182 that has a stopper portion 501 that abuts against the cap member 178 and a nut portion 502 that is fixed to the piston rod 31 and has a loosening prevention portion 532, so the number of parts can be reduced and the assembly man-hours can be reduced. Compared to the case where the first damping force generating mechanisms 85, 86 and the second damping force generating mechanism 140 are fixed to the piston rod 31 using a nut and an annular member, the fixing member 182 can be made more compact in the axial direction, and its length can be shortened compared to the combined axial length of the nut and the annular member. Therefore, the axial length of the shock absorber 1 can be shortened.

[0222] Furthermore, since the buffer 1 has a stopper portion 501 of the fixing member 182 that has a flow path 512 that communicates with the communication hole 195 of the cap member 178, a dedicated part for providing a flow path to connect the communication hole 195 of the cap member 178 to the second chamber 23 is not required. Therefore, the number of parts can be reduced and the assembly man-hours can be reduced. Here, if a flow path communicating with the communication hole 195 of the cap member 178 is formed on an annular member separate from the nut, it is necessary to form the flow path on both the front and back sides to prevent incorrect assembly during the assembly process. However, due to the shape of the fixing member 182, such incorrect assembly does not occur, so it is sufficient to form the flow path 512 communicating with the communication hole 195 only on the contact surface 501b side of the stopper portion 501.

[0223] Furthermore, since the flow path 512 provided in the stopper portion 501 of the fixing member 182 of the buffer 1 is arranged radially toward the outside of the stopper portion 501, the communication hole 195 of the cap member 178 can be well connected to the second chamber 23.

[0224] Furthermore, the shock absorber 1 can be reliably prevented from loosening because the anti-loosening portion 532 provided on the nut portion 502 of the fixing member 182 is prevented from loosening by crimping.

[0225] [Second Embodiment] Next, the second embodiment will be described, focusing mainly on the differences from the first embodiment, based on Figures 11 to 14. Parts common to the configuration of the first embodiment will be represented by the same designation and reference numerals.

[0226] In the second embodiment, as shown in Figures 11 to 14, a fixing member 182A, which is partially different from the fixing member 182 of the first embodiment, is used instead. The fixing member 182A has a stopper portion 501A, which is partially different from the stopper portion 501. The fixing member 182A is a metal part in which the stopper portion 501A and the nut portion 502 are formed integrally without seams.

[0227] As shown in Figure 12, the stopper portion 501A has an insertion hole 511 similar to that of the first embodiment. The stopper portion 501A has a circumferential flow path portion 515A at the end opposite to the nut portion 502 in the axial direction, which is substantially similar to the circumferential flow path portion 515 of the first embodiment and has a wider radial width. The stopper portion 501A has a flow path hole 551 (hole) provided on the bottom surface of the circumferential flow path portion 515A that penetrates the stopper portion 501A in the axial direction. As shown in Figures 11 and 14, the stopper portion 501A has multiple flow path holes 551 (specifically, 8 locations). The multiple flow path holes 551 are arranged at equal intervals in the circumferential direction of the stopper portion 501A. The number of flow path holes 551 can be selected as any number. The circumferential flow path portion 515A and the multiple flow path holes 551 constitute the flow path 512A. The stopper portion 501A does not have the multiple radial flow channels 516 of the first embodiment. As shown in Figure 14, of the multiple flow channel holes 551, two of the flow channel holes 551 are arranged in phase with a pair of diagonal positions on the outer peripheral surface 531a of the tool engagement portion 531 when the fixing member 182A is viewed in the axial direction. In addition, of the multiple flow channel holes 551, two of the flow channel holes 551 are arranged in phase with two sides parallel to the diagonal line connecting the aforementioned diagonal positions when the fixing member 182A is viewed in the axial direction.

[0228] As shown in Figure 12, the radially outer portion of the stopper portion 501A is an outer projection 522A that protrudes from the bottom surface of the circumferential flow channel portion 515A on the opposite side of the nut portion 502 in the axial direction. As shown in Figure 14, the outer projection 522A is an annular shape concentric with the inner projection 521. As shown in Figure 12, the stopper portion 501A has a contact surface 501Ab at the end opposite to the nut portion 502 in the axial direction.

[0229] The contact surface 501Ab is a flat surface that extends in a direction perpendicular to the axis of the stopper portion 501A, and is provided flush with the end of the inner projection 521 opposite to the nut portion 502 in the axial direction of the stopper portion 501A, and the end of the outer projection 522A opposite to the nut portion 502 in the axial direction of the stopper portion 501A.

[0230] Similar to the first embodiment, the components from the annular member 125 to the cap member 178 are stacked sequentially on the main shaft portion 32 of the piston rod 31, with the mounting shaft portion 33 of the piston rod 31 shown in Figure 3 inserted inward. In this state, the fixing member 182A is screwed into the screw hole 533 of the nut portion 502, with the stopper portion 501A facing the cap member 178, onto the male thread 57 of the screw shaft portion 44 that protrudes beyond the cap member 178 of the piston rod 31. At this time, the fixing member 182A is screwed into the screw shaft portion 44 using a tool engaged with the tool engagement portion 531 and tightened to a predetermined tightening torque. As a result, the nut portion 502 of the fixing member 182A is fixed to the piston rod 31, and the components from the annular member 125 to the cap member 178 are clamped axially at least radially inward by the main shaft portion 32 and the fixing member 182A. As a result, the first damping force generating mechanisms 85 and 86 and the second damping force generating mechanism 140, which includes the cap member 178, are fixed to the piston rod 31 by the fixing member 182A.

[0231] In this state, the fixing member 182A has a contact surface 501Ab of the stopper portion 501A that contacts the end face 191a of the bottom portion 191 of the cap member 178. Also in this state, a portion of the tip cylindrical portion 43 of the piston rod 31 is fitted into the insertion hole 511 of the fixing member 182A, and a portion of the screw shaft portion 44 is inserted into it. The fixing member 182A is positioned radially relative to the piston rod 31 by fitting the tip cylindrical portion 43 of the piston rod 31 into the insertion hole 511. Also in this state, the fixing member 182A has a circumferential flow path portion 515A of the stopper portion 501A that faces a communication hole 195 provided in the end face 191a of the bottom portion 191 of the cap member 178, and therefore the flow path 512A of the stopper portion 501A communicates with the communication hole 195. Since the fixing member 182A is positioned in the second chamber 23, the flow path 512A communicates with the second chamber 23 through multiple flow path holes 551, and as a result, the communication hole 195 communicates with the second chamber 23 via the flow path 512A.

[0232] After the fixing member 182A is tightened to the piston rod 31, the anti-loosening portion 532 is crimped radially inward and plastically deformed, causing deformation of the female thread 534 formed in the anti-loosening portion 532 and the male thread 57 of the piston rod 31. As a result, the fixing member 182A is prevented from loosening relative to the piston rod 31, i.e., its rotation is restricted.

[0233] Even when using the fixing member 182A with the above configuration, the same effects as in the first embodiment can be achieved.

[0234] Furthermore, the fixing member 182A allows the contact surface 501Ab of the stopper portion 501A to be a double annular shape, and the area of ​​the contact surface 501Ab can be increased, because the flow path 512A provided in the stopper portion 501A includes the flow path hole 551.

[0235] [Third Embodiment] Next, the third embodiment will be described, focusing mainly on the differences from the first embodiment, based on Figures 15 to 18. Parts common to the configuration of the first embodiment will be represented by the same designation and reference numerals.

[0236] In the third embodiment, as shown in Figures 15 to 18, a fixing member 182B, which is slightly different from the fixing member 182 of the first embodiment, is used instead. The fixing member 182B has the shape shown in Figures 15 to 18. The fixing member 182 has a stopper portion 501B and a nut portion 502B shown in Figures 15 to 17. The stopper portion 501B is on one side of the fixing member 182B in the axial direction, and the nut portion 502B is on the other side of the fixing member 182B in the axial direction. The fixing member 182B is a metal part in which the stopper portion 501B and the nut portion 502B are formed integrally without seams.

[0237] The stopper portion 501B has a tool engagement portion 531B on its radially outward side. As shown in Figures 15 and 18, the outer circumferential surface 531Ba of the tool engagement portion 531B is hexagonal when viewed in the axial direction. As shown in Figure 16, the stopper portion 501B has an insertion hole 511 in the radial center that is aligned in the axial direction, similar to that of the first embodiment. The stopper portion 501B has a contact surface 501Bb and a flow path 512B at the end opposite to the nut portion 502B in the axial direction.

[0238] The contact surface 501Bb is located on the opposite side of the nut portion 502B in the axial direction of the stopper portion 501B, and is planar in shape, extending in a direction perpendicular to the axis of the stopper portion 501B.

[0239] The flow path 512B is recessed from the contact surface 501Bb toward the nut portion 502B in the axial direction of the stopper portion 501B. As shown in Figure 18, the flow path 512B has one circumferential flow path portion 515B and multiple radial flow path portions 516B.

[0240] The circumferential flow channel section 515B is formed between the outer circumferential surface 531Ba of the stopper section 501B and the insertion hole 511, forming a roughly annular shape coaxial with them. The distance from the center of the stopper section 501B in the radial direction to the center of the groove width of the circumferential flow channel section 515B is approximately equal to the distance from the center of the cap member 178 in the radial direction to the center of the communication hole 195.

[0241] The radial flow channel section 516B extends radially outward from the circumferential flow channel section 515B to the stopper section 501B. One end of the radial flow channel section 516B opens into the circumferential flow channel section 515B, and the other end of the radial flow channel section 501B opens to the outer circumferential surface 531Ba of the stopper section 501B. Multiple radial flow channel sections 516B (specifically, six locations) are formed in the stopper section 501B. The multiple radial flow channel sections 516B are arranged at equal intervals in the circumferential direction of the stopper section 501B. Each of the multiple radial flow channel sections 516B is positioned at one of the multiple vertex positions on the outer circumferential surface 531Ba when the stopper section 501B is viewed in the axial direction. The flow path 512B provided in the stopper portion 501B has multiple radial flow path sections 516B arranged radially outward from the stopper portion 501B.

[0242] As shown in Figure 16, the portion between the circumferential flow channel 515B and the insertion hole 511 is an inner projection 521B that protrudes from the bottom surface of the circumferential flow channel 515B on the opposite side of the nut portion 502B in the axial direction of the stopper portion 501B. The inner projection 521B is annular, as shown in Figure 18. Between adjacent radial flow channel sections 516B in the circumferential direction of the stopper portion 501B, as shown in Figure 16, there is an outer projection 522B that protrudes from the bottom surface of the circumferential flow channel 515B and the bottom surface of the radial flow channel section 516B on the opposite side of the nut portion 502B in the axial direction of the stopper portion 501B. As shown in Figure 18, the stopper portion 501B has the same number of outer projections 522B as the radial flow channel sections 516B (specifically, 6 locations). The multiple outer projections 522B are arranged at equal intervals in the circumferential direction of the stopper portion 501B. Each of the multiple external protrusions 522B is positioned at the location of one of the multiple sides of the outer peripheral surface 531Ba when the stopper portion 501B is viewed in the axial direction.

[0243] The aforementioned contact surface 501Bb is provided flush with the end of the inner projection 521B that is opposite to the nut portion 502B in the axial direction of the stopper portion 501B, and with the end of the multiple outer projections 522B that is opposite to the nut portion 502B in the axial direction of the stopper portion 501B.

[0244] As shown in Figures 15 to 17, the nut portion 502B has a loosening prevention portion 532B. As shown in Figure 16, the nut portion 502B has a screw hole 533B with an internal thread 534B formed on its inner circumference. The screw hole 533B is located in the radial center of the nut portion 502B and is positioned along the axial direction of the nut portion 502B. The screw hole 533B is slightly smaller in diameter than the insertion hole 511 and communicates with the insertion hole 511. The screw hole 533B and the insertion hole 511 constitute a through hole 535B that penetrates the fixing member 182B in the axial direction.

[0245] The anti-loosening portion 532B is located on the axial side of the nut portion 502B, opposite to the stopper portion 501B. In other words, the fixing member 182B has the anti-loosening portion 532B positioned at the end of the nut portion 502B. The anti-loosening portion 532B is cylindrical before it is assembled to the piston rod 31.

[0246] As shown in Figure 3, the mounting shaft portion 33 of the piston rod 31 is inserted inward, and the parts from the annular member 125 to the cap member 178 are stacked sequentially on the main shaft portion 32 of the piston rod 31, similar to the first embodiment. In this state, the fixing member 182B is screwed into the screw hole 533B of the nut portion 502B, with the stopper portion 501B facing the cap member 178, onto the male thread 57 of the screw shaft portion 44 that protrudes beyond the cap member 178 of the piston rod 31. At this time, the fixing member 182B is screwed into the screw shaft portion 44 using a tool engaged with the tool engagement portion 531B and tightened to a predetermined tightening torque. As a result, the nut portion 502B of the fixing member 182B is fixed to the piston rod 31, and the parts from the annular member 125 to the cap member 178 are clamped axially at least radially inward by the main shaft portion 32 and the fixing member 182B. As a result, the first damping force generating mechanisms 85 and 86 and the second damping force generating mechanism 140, which includes the cap member 178, are fixed to the piston rod 31 by the fixing member 182B.

[0247] In this state, the fixing member 182B has a contact surface 501Bb of the stopper portion 501B that contacts the end face 191a of the bottom portion 191 of the cap member 178. Also in this state, a portion of the tip cylindrical portion 43 of the piston rod 31 is fitted into the insertion hole 511 of the fixing member 182B, and a portion of the screw shaft portion 44 is inserted into it. The fixing member 182B is positioned radially relative to the piston rod 31 by fitting the tip cylindrical portion 43 of the piston rod 31 into the insertion hole 511. Also in this state, the fixing member 182B has a circumferential flow path portion 515B of the stopper portion 501B that faces a communication hole 195 provided in the end face 191a of the bottom portion 191 of the cap member 178, and therefore the flow path 512B of the stopper portion 501B communicates with the communication hole 195. Since the fixing member 182B is positioned in the second chamber 23, the flow path 512B communicates with the second chamber 23 in multiple radial flow path sections 516B, and as a result, the communication hole 195 communicates with the second chamber 23 via the flow path 512B.

[0248] After the fixing member 182B is tightened to the piston rod 31, the anti-loosening portion 532B is crimped radially inward and plastically deformed, causing deformation of the female thread 534B formed in the anti-loosening portion 532B and the male thread 57 of the piston rod 31. As a result, the fixing member 182B is prevented from loosening relative to the piston rod 31, i.e., its rotation is restricted.

[0249] Even when using the fixing member 182B with the above configuration, the same effects as in the first embodiment can be achieved.

[0250] Furthermore, since the fixing member 182B is provided with a tool engagement portion 531B on the stopper portion 501, the axial length can be further shortened. [Explanation of Symbols]

[0251] 1... Shock absorber, 4... Cylinder, 22... First chamber, 23... Second chamber, 21... Piston, 31... Piston rod, 85, 86... First damping force generating mechanism, 132, 152... First passage, 140... Second damping force generating mechanism, 166... ​​Valve seat member, 178... Cap member, 182, 182A, 182B... Fixing member, 191... Bottom, 191a... End face, 193... Outer cylindrical part, 195... Communication hole, 291, 315... Second passage, 301...sub-valve mechanism (e.g., first sub-valve), 321...sub-valve mechanism (e.g., second sub-valve), 501, 501A, 501B...stopper part, 501b, 501Ab, 501Bb...contact surface, 502, 502B...nut part, 512, 512A, 512B...flow path, 531B...tool engagement part, 532, 532B...loosening prevention part, 551...flow path hole (hole), L...oil (working fluid).

Claims

1. A cylinder in which the working fluid is sealed, A piston is slidably mounted within the cylinder and divides the cylinder into two chambers, A piston rod connected to the piston and extending to the outside of the cylinder, The movement of the piston causes the working fluid to flow from the upstream chamber to the downstream chamber within the cylinder through a first passage and a second passage, A first damping force generating mechanism is provided in the first passage formed in the piston and generates a damping force, A second damping force generating mechanism is provided in the second passage, which is parallel to the first passage, and generates a damping force. A fixing member for fixing the first damping force generating mechanism and the second damping force generating mechanism to the piston rod, It has, The second damping force generation mechanism is, An annular valve seat member is arranged in one of the aforementioned chambers, A first sub-valve is provided on one side of the second passage formed in the valve seat member, and a second sub-valve is provided on the other side. A bottomed cylindrical cap member having an outer cylindrical portion and a bottom portion, with a communication hole provided in the bottom portion, Equipped with, The aforementioned fixing member is A stopper portion having a contact surface that faces the cap member and contacts the cap member, and a flow path that communicates with the communication hole, It comprises a nut portion that is fixed to the piston rod, A shock absorber characterized by having a loosening prevention part positioned at the end of the nut portion.

2. The buffer according to claim 1, wherein the stopper portion abuts against the end face of the cap member, and the flow path communicates with the communication hole provided on the end face.

3. The buffer according to claim 2, wherein the flow path provided in the stopper portion is arranged radially toward the outside of the stopper portion.

4. The buffer according to claim 2, wherein the flow path provided in the stopper portion includes a hole.

5. The shock absorber according to claim 2, wherein the stopper portion is provided with a tool engagement portion.

6. The shock absorber according to any one of claims 1 to 5, wherein the anti-loosening portion provided on the nut portion is prevented from loosening by crimping.

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