Buffer

Abstract

This shock absorber includes a cylinder, a piston, a piston rod, a first passage, a first damping force generation mechanism, a second passage, and a second damping force generation mechanism. The first damping force generation mechanism includes: a first valve which has a radially inward side fixed from both sides in an axial direction and which is disposed to close the first passage; and one or a plurality of second valves each of which has a fixed portion on the radially inward side fixed together with the first valve from both ends in the axial direction and each of which generates a biasing force toward a direction of closing the first passage. Each second valve is formed so as to have a diameter larger than an inner diameter of a seat portion provided on an outer circumference side of the first passage, and a deflection promoting part is formed in at least one of the second valves to promote more axial deflection on the radially outside than on the radially inside in a portion on radially outside the fixed part.

Description

[Technical field]

[0001] The present invention relates to a shock absorber. This application claims priority based on Patent Application No. 2022-067008, filed in Japan on April 14, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Some shock absorbers have a pressure-controlled valve that applies back pressure to the valve in the valve closing direction (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-2976 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to improve the durability of valves in shock absorbers.

[0005] Therefore, an object of the present invention is to provide a shock absorber capable of improving the durability of a valve. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention includes a cylinder in which a working fluid is sealed, a piston slidably fitted within the cylinder and dividing the interior of the cylinder into two cylinder chambers, a piston rod having a first end connected to the piston and a second end extending outside the cylinder, a first passage through which the working fluid flows out of at least one of the cylinder chambers as the piston moves, a first damping force generating mechanism provided in the first passage and generating a damping force, and a valve closing mechanism provided in parallel with the first passage, which causes the working fluid to flow out of at least one of the cylinder chambers as the piston moves and which accelerates the first damping force generating mechanism in a valve closing direction. the first damping force generating mechanism includes a first valve whose radially inner side is fixed from both axial sides and arranged to be able to close the first passage; and one or more second valves whose radially inner fixed parts are fixed together with the first valve from both axial ends and generate a biasing force in a direction to close the first passage, the second valves being formed with a diameter larger than the inner diameter of a seat part provided on the outer periphery of the first passage, and at least one of the second valves is formed with a deflection promoting part in a part radially outer than the fixed part that promotes axial deflection more radially outward than the radially inner side. Effect of the Invention

[0007] According to the above aspect of the present invention, the durability of the valve can be improved. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a piston, a first damping force generating mechanism, a second damping force generating mechanism, a frequency varying mechanism, etc. of the shock absorber of the first embodiment. [Diagram 3] FIG. 2 is a half-side cross-sectional view showing a first damping force generating mechanism and a second damping force generating mechanism of the shock absorber according to the first embodiment. [Figure 4]FIG. 2 is a half-side cross-sectional view showing a frequency sensitive mechanism and the like of the shock absorber of the first embodiment. [Diagram 5] FIG. 2 is a plan view showing a valve disc of the shock absorber according to the first embodiment. [Figure 6] FIG. 11 is a plan view showing a valve disc of a shock absorber according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a plan view showing a valve disc of a shock absorber according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] A shock absorber according to a first embodiment will be described below with reference to Figures 1 to 5. For ease of explanation, the upper side in Figures 1 to 5 will be referred to as "upper", and the lower side in Figures 1 to 5 will be referred to as "lower".

[0010] As shown in FIG. 1, the shock absorber 1 of the first embodiment is a twin-cylinder hydraulic shock absorber. The shock absorber 1 is used in a suspension device for a vehicle, specifically an automobile. The shock absorber 1 includes a cylinder 2 in which oil L is sealed as a working fluid. The cylinder 2 has an inner cylinder 3 and an outer cylinder 4. The inner cylinder 3 is cylindrical. The outer cylinder 4 is cylindrical with a bottom. The inner diameter of the outer cylinder 4 is larger than the outer diameter of the inner cylinder 3. The inner cylinder 3 is disposed radially inside the outer cylinder 4. The central axis of the inner cylinder 3 and the central axis of the outer cylinder 4 coincide with each other. A reservoir chamber 6 is formed between the inner cylinder 3 and the outer cylinder 4.

[0011] The outer cylinder 4 has a body 11 and a bottom 12. The body 11 and the bottom 12 are seamlessly formed as a single unit. The body 11 is cylindrical. The bottom 12 closes the lower part of the body 11. An attachment eye (not shown) is fixed to the outside of the bottom 12, opposite the body 11 in the axial direction.

[0012] The shock absorber 1 is provided with a piston 18. The piston 18 is inserted into the inner tube 3 of the cylinder 2. The piston 18 is fitted slidably in the inner tube 3 of the cylinder 2. The piston 18 divides the inner tube 3 into two chambers, a cylinder chamber 19 on one side and a cylinder chamber 20 on the other side. In the axial direction of the cylinder 2, the cylinder chamber 19 is located on the opposite side of the piston 18 from the bottom 12. In the axial direction of the cylinder 2, the cylinder chamber 20 is located on the bottom 12 side from the piston 18. An oil liquid L is sealed in the cylinder chamber 19 and the cylinder chamber 20 in the inner tube 3 as a working fluid. An oil liquid L and a gas G are sealed in a reservoir chamber 6 between the inner tube 3 and the outer tube 4 as a working fluid.

[0013] The shock absorber 1 includes a piston rod 21. A first end portion on one end side in the axial direction of the piston rod 21 is disposed within the inner tube 3 of the cylinder 2. The first end portion of the piston rod 21 is fastened to the piston 18. A second end portion of the piston rod 21 on the opposite side in the axial direction to the first end portion extends from the cylinder 2 to the outside of the cylinder 2.

[0014] Piston 18 is fixed to piston rod 21. Therefore, piston 18 and piston rod 21 move together. In shock absorber 1, the stroke in which piston rod 21 moves in a direction to increase the amount of protrusion from cylinder 2 is the extension stroke in which the overall length increases. In shock absorber 1, the stroke in which piston rod 21 moves in a direction to decrease the amount of protrusion from cylinder 2 is the compression stroke in which the overall length contracts. In shock absorber 1, piston 18 moves towards cylinder chamber 19 during the extension stroke. In shock absorber 1, piston 18 moves towards cylinder chamber 20 during the compression stroke.

[0015] A rod guide 22 is fitted to the upper end opening side of the inner cylinder 3 and the upper end opening side of the outer cylinder 4. A seal member 23 is fitted to the outer cylinder 4 above the rod guide 22. Both the rod guide 22 and the seal member 23 are annular. The piston rod 21 is inserted into the radial inside of each of the rod guide 22 and the seal member 23. The piston rod 21 slides along the axial direction of each of the rod guide 22 and the seal member 23. The piston rod 21 extends from the inside of the cylinder 2 to the outside of the cylinder 2 beyond the seal member 23.

[0016] The rod guide 22 restricts the piston rod 21 from moving radially relative to the inner tube 3 and the outer tube 4 of the cylinder 2. When the piston rod 21 is fitted into the rod guide 22, the piston 18 is fitted into the inner tube 3. This causes the central axis of the piston rod 21 to coincide with the central axis of the cylinder 2. The rod guide 22 supports the piston rod 21 so that it can move in the axial direction of the piston rod 21. The outer periphery of the seal member 23 is in close contact with the outer tube 4. The inner periphery of the seal member 23 is in close contact with the outer periphery of the piston rod 21. The piston rod 21 moves in the axial direction of the seal member 23 relative to the seal member 23. The seal member 23 prevents the oil L in the inner tube 3 and the high-pressure gas G and oil L in the reservoir chamber 6 from leaking out to the outside.

[0017] The outer periphery of the rod guide 22 is larger in diameter at the upper part than at the lower part. The smaller diameter lower part of the rod guide 22 fits into the inner periphery of the upper end of the inner cylinder 3. The larger diameter upper part of the rod guide 22 fits into the inner periphery of the upper part of the outer cylinder 4. A base valve 25 is installed on the bottom 12 of the outer cylinder 4. The base valve 25 is positioned radially relative to the outer cylinder 4. The inner periphery of the lower end of the inner cylinder 3 fits into the base valve 25. An upper end portion of the outer cylinder 4 is crimped toward the inside in the radial direction of the outer cylinder 4. The seal member 23 is fixed to the cylinder 2 by being sandwiched between this crimped portion and the rod guide 22.

[0018] The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28. The main shaft portion 27 and the mounting shaft portion 28 are both rod-shaped. The mounting shaft portion 28 has an outer diameter smaller than that of the main shaft portion 27. The mounting shaft portion 28 is disposed within the cylinder 2. The piston 18 is attached to the mounting shaft portion 28. The main shaft portion 27 has a shaft step portion 29. The shaft step portion 29 is provided at the end of the main shaft portion 27 on the mounting shaft portion 28 side in the axial direction. The shaft step portion 29 extends in a direction perpendicular to the central axis of the piston rod 21.

[0019] In the piston rod 21, a groove 30 is formed on the outer periphery of the mounting shaft portion 28. The groove 30 extends in the axial direction of the mounting shaft portion 28. The groove 30 is formed by cutting out the outer periphery of the mounting shaft portion 28 in a plane parallel to the central axis of the mounting shaft portion 28. The groove 30 is formed in two places spaced apart in the circumferential direction of the mounting shaft portion 28. A threaded portion 31 is formed on the outer periphery of the end portion of the mounting shaft portion 28 on the opposite side to the main shaft portion 27 from the groove 30 in the axial direction of the mounting shaft portion 28.

[0020] The shock absorber 1 is connected to the vehicle body with, for example, the portion of the piston rod 21 protruding from the cylinder 2 disposed at the top. In this case, the shock absorber 1 is connected to the vehicle wheel side with a mounting eye (not shown) provided on the cylinder 2 disposed at the bottom. Conversely, the shock absorber 1 may be connected to the vehicle body with the cylinder 2 side. In this case, the piston rod 21 of the shock absorber 1 is connected to the wheel side.

[0021] As shown in FIG. 2, the piston 18 has a piston body 35 and a sliding member 36. The piston body 35 is formed by combining a divided body 33 and a divided body 34. The divided bodies 33 and 34 are both made of metal and are both annular. The divided bodies 33 and 34 have an inner diameter smaller than that of the divided body 34. The sliding member 36 is made of synthetic resin and is annular and band-like. The sliding member 36 is integrally attached to the outer circumferential surface of the piston body 35 in a state in which the divided bodies 33 and 34 are combined. As a result, the divided bodies 33 and 34 and the sliding member 36 are integrated to form the piston 18. The divided body 33 of the piston 18 is fitted to the mounting shaft portion 28 of the piston rod 21. The piston 18 slides relative to the inner cylinder 3 with the sliding member 36 in contact with the inner cylinder 3.

[0022] The piston body 35 is provided with a passage hole 37, a passage groove 38, a passage hole 39, and a passage groove 40. The passage hole 37 extends in the axial direction of the piston body 35. A plurality of the passage holes 37 are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35 (only one is shown in FIG. 2 because the cross section is shown). The passage hole 39 extends in the axial direction of the piston body 35. A plurality of the passage holes 39 are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35 (only one is shown in FIG. 2 because the cross section is shown). The piston body 35 is formed with the passage holes 37 and the passage holes 39 alternately at equal pitches in the circumferential direction of the piston body 35.

[0023] The passage groove 38 is formed in the divided body 34 of the piston body 35 in a ring shape in the circumferential direction of the divided body 34. The passage groove 38 is formed at the end of the divided body 34 opposite the divided body 33 in the axial direction. All the passage holes 37 open to the passage groove 38 at the end side in the axial direction of the piston body 35. The passage groove 40 is formed in the divided body 33 of the piston body 35 in a ring shape in the circumferential direction of the divided body 33. The passage groove 40 is formed at the end of the divided body 33 opposite the divided body 34 in the axial direction. All the passage holes 39 open to the passage groove 40 at the end side opposite the passage groove 38 in the axial direction of the piston body 35. In the piston 18, the inside of the multiple passage holes 37 and the inside of the passage groove 38 form a first passage 43. The first passage 43 penetrates the piston 18 in the axial direction of the piston 18. In the piston 18, the insides of the plurality of passage holes 39 and the insides of the passage grooves 40 form first passages 44. The first passages 44 penetrate the piston 18 in the axial direction of the piston 18. The first passages 43 and the first passages 44 are both provided in the piston 18.

[0024] The first passage 43 is provided with a first damping force generating mechanism 41. The first damping force generating mechanism 41 opens and closes the first passage 43 to generate a damping force. The first damping force generating mechanism 41 is disposed on the cylinder chamber 20 side, which is one end side in the axial direction of the piston 18, and is attached to the piston rod 21. As a result, the first passage 43 becomes a passage through which the oil L as a working fluid moves from the cylinder chamber 19 to the cylinder chamber 20 by the movement of the piston 18 toward the cylinder chamber 19 side. In other words, the first passage 43 is a passage through which the oil L flows out from the cylinder chamber 19, which is the upstream side, to the cylinder chamber 20, which is the downstream side, by the movement of the piston 18 in the extension stroke. The first damping force generating mechanism 41 is an extension-side damping force generating mechanism that suppresses the flow of the oil L from the first passage 43 to the cylinder chamber 20, which occurs in the extension stroke, to generate a damping force.

[0025] The first passage 44 is provided with a first damping force generating mechanism 42. The first damping force generating mechanism 42 opens and closes the first passage 44 to generate a damping force. The first damping force generating mechanism 42 is disposed on the cylinder chamber 19 side, which is the other end side in the axial direction of the piston 18, and is attached to the piston rod 21. As a result, the first passage 44 becomes a passage through which the oil L moves from the cylinder chamber 20 to the cylinder chamber 19 as the piston 18 moves toward the cylinder chamber 20. In other words, the first passage 44 is a passage through which the oil L flows from the cylinder chamber 20, which is the upstream side, to the cylinder chamber 19, which is the downstream side, as the piston 18 moves during the compression stroke. The first damping force generating mechanism 42 is a compression-side damping force generating mechanism that suppresses the flow of the oil L from the first passage 44 to the cylinder chamber 19 during the compression stroke to generate a damping force.

[0026] The piston body 35 has an insertion hole 45 formed in its radial center, penetrating the piston body 35 in the axial direction. The mounting shaft portion 28 of the piston rod 21 is inserted through the insertion hole 45. The insertion hole 45 has a smaller diameter in the axial direction at a portion formed in the split body 33 on the cylinder chamber 19 side than at a portion formed in the split body 34 on the cylinder chamber 20 side. The piston body 35 fits onto the mounting shaft portion 28 of the piston rod 21 in the split body 33 having the smaller inner diameter.

[0027] An inner sheet 46 and a valve seat portion 48 (seat portion) are formed at the end of the piston body 35 on the cylinder chamber 20 side in the axial direction. The inner sheet 46 and the valve seat portion 48 are both annular. The inner sheet 46 is disposed radially inward of the opening of the passage groove 38 on the cylinder chamber 20 side of the piston body 35. The valve seat portion 48 is disposed radially outward of the opening of the passage groove 38 on the cylinder chamber 20 side of the piston body 35. The valve seat portion 48 is provided on the outer periphery of the first passage 43. The valve seat portion 48 constitutes a part of the first damping force generating mechanism 41.

[0028] An inner seat 47 and a valve seat portion 49 are formed at the end of the piston body 35 on the cylinder chamber 19 side in the axial direction. Both the inner seat 47 and the valve seat portion 49 are annular. The inner seat 47 is disposed radially inward of the opening of the passage groove 40 on the cylinder chamber 19 side of the piston body 35. The valve seat portion 49 is disposed radially outward of the opening of the passage groove 40 on the cylinder chamber 19 side of the piston body 35. The valve seat portion 49 is provided on the outer periphery of the first passage 44. The valve seat portion 49 constitutes a part of the first damping force generating mechanism 42.

[0029] In the piston body 35, openings of all the passage holes 39 on the cylinder chamber 20 side are arranged on the opposite side of the piston body 35 to the passage groove 38 of the valve seat portion 48 in the radial direction of the piston body 35. In the piston body 35, openings of all the passage holes 37 on the cylinder chamber 19 side are arranged on the opposite side of the piston body 35 to the passage groove 40 of the valve seat portion 49 in the radial direction of the piston body 35.

[0030] As shown in Fig. 3, on the inner seat 46 side in the axial direction of the piston 18, in order from the piston 18 side in the axial direction of the piston 18, one disk 50, one disk 51, one valve disk 52, a plurality of (specifically, four) valve disks 53 (second valves), one pilot valve 60 (first valve), one disk 61, one pilot case 62, one disk 63, a plurality of (specifically, six) disks 64, one disk 65, and one disk 66 are provided. The disks 50, 51, 61, 63 to 66, the valve disks 52, 53, and the pilot case 62 are all made of metal. The disks 50, 51, 61, 63 to 66, and the valve disks 52, 53 are all circular flat plates with holes of a certain thickness. The mounting shaft portion 28 of the piston rod 21 is fitted inside each of the disks 50, 51, 61, 63-66 and the valve disks 52, 53. The pilot valve 60 and the pilot case 62 are both annular. The mounting shaft portion 28 of the piston rod 21 is fitted inside each of the pilot valve 60 and the pilot case 62.

[0031] The pilot case 62 is cylindrical with a bottom. A through hole 70 is formed in the center of the pilot case 62 in the radial direction. The through hole 70 passes through the pilot case 62 in the axial direction. The pilot case 62 has a bottom 71, an inner cylindrical portion 72, an outer cylindrical portion 73, an inner seat portion 74, and a valve seat portion 75.

[0032] The through hole 70 has a smaller diameter on the piston 18 side in the axial direction than on the opposite side to the piston 18, and the mounting shaft portion 28 of the piston rod 21 is fitted into this smaller diameter portion. The bottom portion 71 is in the shape of a disk having a hole. A passage hole 78 is formed in the bottom portion 71 radially outward of the through hole 70, penetrating the bottom portion 71 in the axial direction of the bottom portion 71. The inner cylindrical portion 72 is cylindrical and protrudes from the inner peripheral edge of the bottom portion 71 along the axial direction of the bottom portion 71 toward the piston 18 . The outer cylindrical portion 73 is cylindrical and protrudes from the outer peripheral edge of the bottom portion 71 along the axial direction of the bottom portion 71 on the same side as the inner cylindrical portion 72 . The passage hole 78 is disposed radially of the bottom 71 between the inner cylindrical portion 72 and the outer cylindrical portion 73 .

[0033] The inner seat portion 74 is annular, and protrudes slightly from the inner peripheral edge of the bottom portion 71 toward the axially opposite side of the inner cylindrical portion 72. The inner seat portion 74 is formed with a passage groove 79 that penetrates the inner seat portion 74 in the radial direction. The valve seat portion 75 is annular and has a larger diameter than the inner seat portion 74. The valve seat portion 75 protrudes from the bottom portion 71 along the axial direction of the bottom portion 71 on the same side as the inner seat portion 74, radially outward of the inner seat portion 74. The passage hole 78 is disposed between the inner seat portion 74 and the valve seat portion 75 in the radial direction of the bottom portion 71. The passage in the passage groove 79 of the inner seat portion 74 is constantly in communication with the passage in the groove portion 30 of the piston rod 21 and the passage in the passage hole 78.

[0034] The disc 50 abuts against the inner seat 46 of the piston 18. The outer diameter of the disc 50 is constant over the entire circumference and is smaller than the inner diameter of the valve seat portion 48. A notch 81 extending from the inner periphery is formed in the disc 50. The passage in the notch 81 is constantly in communication with the passage in the passage groove 38 of the first passage 43 of the piston 18 and the passage in the groove portion 30 of the piston rod 21.

[0035] The disk 51 abuts against the disk 50 on the axial side opposite to the piston 18. The disk 51 has a constant outer diameter over its entire circumference, a constant inner diameter over its entire circumference, and a constant radial width. The outer diameter of the disk 51 is equal to the outer diameter of the disk 50.

[0036] Valve disc 52 abuts against the side of disc 51 opposite to disc 50 in the axial direction. A notched fixed orifice 92 is formed on the outer periphery of valve disc 52. The outer diameter of the portion of valve disc 52 excluding fixed orifice 92 is larger than the inner diameter of the tip face on the protruding tip side of valve seat portion 48 in the axial direction of piston 18, and is equal to the outer diameter of this tip face.

[0037] The outer circumferential side of the valve disc 52 abuts against the valve seat portion 48 of the piston 18. The valve disc 52 opens and closes the opening of the first passage 43 formed in the piston 18 by moving away from and abutting against the valve seat portion 48. The fixed orifice 92 of the valve disc 52 allows communication between the inside and outside of the valve seat portion 48 in the radial direction, even when the valve disc 52 is in contact with the valve seat portion 48. The valve disc 52 abuts against the valve seat portion 48 while slightly elastically deforming. As a result, the valve disc 52 generates a biasing force in the direction of abutting against the valve seat portion 48 by its own elasticity.

[0038] The multiple valve discs 53 are arranged on the opposite side of the valve disc 52 to the disc 51 in the axial direction. The multiple valve discs 53 are stacked along the axial direction of the valve disc 52. Of the multiple valve discs 53, the valve disc 53 closest to the valve disc 52 in the stacking direction abuts against the valve disc 52.

[0039] The multiple valve discs 53 all have a constant outer diameter over their entire circumference, and all have a constant inner diameter over their entire circumference. The multiple valve discs 53 all have a constant radial width. The multiple valve discs 53 have the same outer diameter and the same inner diameter. All of the valve discs 53 have the same shape when viewed in the axial direction. Furthermore, the thickness of each of the multiple valve discs 53 is appropriately set. At least one of the multiple valve discs 53 has a different thickness from the rest. Of course, it is possible for all of the multiple valve discs 53 to have the same thickness, or it is also possible for all of the multiple valve discs 53 to have different thicknesses.

[0040] The outer diameter of each of the multiple valve discs 53 is equal to the outer diameter of the valve disc 52 excluding the fixed orifice 92. Therefore, the outer diameter of each of the multiple valve discs 53 is larger than the inner diameter of the tip face on the protruding tip side of the valve seat portion 48. The outer diameter of each of the multiple valve discs 53 is equal to the outer diameter of the tip face on the protruding tip side of the valve seat portion 48.

[0041] The multiple valve discs 53 are slightly elastically deformed as they abut against the valve disc 52. As a result, the multiple valve discs 53 each generate a biasing force in a direction such that they abut against the valve seat portion 48 due to their respective elasticity. As a result, the multiple valve discs 53 apply a biasing force to the valve disc 52 in a direction such that they abut against the valve seat portion 48 due to their respective elasticity. There does not need to be multiple valve discs 53, and only one valve disc is sufficient.

[0042] The pilot valve 60 comprises a pilot disk 85 and a seal member 86 . The pilot disk 85 is made of metal and has a circular flat plate shape with holes. The pilot disk 85 has a constant outer diameter over the entire circumference and a constant inner diameter over the entire circumference. The pilot disk 85 has a constant width in the radial direction.

[0043] The mounting shaft portion 28 of the piston rod 21 is fitted inside the pilot disc 85. Of the multiple valve discs 53, the valve disc 53 closest to the piston 18 in the axial direction abuts against the pilot disc 85 of the pilot valve 60. The outer diameter of the pilot disc 85 is larger than the outer diameter of the valve disc 53. Thus, the pilot valve 60 is formed with an outer diameter larger than that of the valve disc 53.

[0044] The pilot disc 85 is slightly elastically deformed and abuts against the valve disc 53. As a result, the pilot disc 85 generates a biasing force due to its elasticity in a direction in which it abuts against the valve seat portion 48. As a result, the pilot disc 85 applies a biasing force to the valve discs 52, 53 in a direction in which it abuts against the valve seat portion 48 due to its elasticity.

[0045] The seal member 86 is made of rubber and is bonded to the pilot disc 85 on the axially opposite side to the valve disc 53. The seal member 86 is fixed to the outer periphery of the pilot disc 85 and has an annular shape. The seal member 86 is fitted liquid-tightly over the entire circumference of the inner periphery of the outer cylindrical portion 73 of the pilot case 62. The seal member 86 is axially slidable relative to the inner periphery of the outer cylindrical portion 73. The seal member 86 constantly seals the gap between the pilot valve 60 and the outer cylindrical portion 73.

[0046] One end of the pilot valve 60 in the axial direction is defined as a first axial end, and the other end opposite to the first axial end is defined as a second axial end. The pilot valve 60 has a seal member 86 at the first axial end. In addition, a valve disc 53 is provided at the second axial end of the pilot valve 60.

[0047] The valve disc 52, the multiple valve discs 53, and the pilot valve 60 constitute a damping valve 91. A first passage 43 is formed between the damping valve 91 and the valve seat portion 48 of the piston 18. When the damping valve 91 is lifted off the valve seat portion 48 of the piston 18 and opens, the first passage 43 is opened and the oil L flows from the first passage 43 to the cylinder chamber 20. At that time, the damping valve 91 suppresses the flow of the oil L between the valve seat portion 48. The damping valve 91 constitutes a first damping force generating mechanism 41 on the extension side. In the damping valve 91, a fixed orifice 92 is formed in the valve disc 52, which communicates the first passage 43 with the cylinder chamber 20 even when the damping valve 91 is in contact with the valve seat portion 48. The fixed orifice 92 constitutes the first passage 43 and constitutes the first damping force generating mechanism 41. Here, it is also possible to configure the first passage 43 without providing the fixed orifice 92. For this reason, the first passage 43 may be a passage through which the oil L flows out from at least one of the cylinder chambers 19 and 20 as the piston 18 moves.

[0048] As described above, in the first damping force generating mechanism 41, the pilot valve 60 is disposed so as to be able to close the first passage 43 via the valve discs 52, 53. The valve disc 52, the multiple valve discs 53 and the pilot disc 85, all of which constitute the first damping force generating mechanism 41, each generate a biasing force in a direction to close the first passage 43 by their own elasticity.

[0049] The disk 61 abuts against the pilot disk 85 of the pilot valve 60 on the side opposite to the valve disk 53. The disk 61 abuts against the inner cylindrical portion 72 of the pilot case 62. The disk 61 has an outer diameter equal to the outer diameter of the inner seat 46 of the piston 18. The disk 63 abuts against an inner seat portion 74 of the pilot case 62. The outer diameter of the disk 63 is smaller than the inner diameter of a valve seat portion 75 of the pilot case 62.

[0050] Of the multiple discs 64, the disc 64 on the disc 63 side in the axial direction can be seated on the valve seat portion 75. The multiple discs 64 constitute a disc valve 99. The disc valve 99 can be seated and removed from the valve seat portion 75. The outer diameter of the disc valve 99 decreases as it moves away from the valve seat portion 75 in the axial direction. The disc 65 has an outer diameter smaller than the minimum outer diameter of the disc valve 99 . The disk 66 has an outer diameter larger than the outer diameter of the disk 65 .

[0051] A back pressure chamber 100 is formed between the bottom 71, inner cylindrical portion 72, and outer cylindrical portion 73 of the pilot case 62, the pilot valve 60, and the disk 61, between the bottom 71, inner seat portion 74, and valve seat portion 75 of the pilot case 62, the disk 63, and the disk valve 99, and inside the passage hole 78 of the pilot case 62. The back pressure chamber 100 applies pressure to the valve disks 53 and the valve disk 52 in the direction of the piston 18 via the pilot valve 60. In other words, the back pressure chamber 100 applies internal pressure to the damping valve 91 in the valve closing direction in which the damping valve 91 is seated on the valve seat portion 48. At that time, the pilot valve 60 is bent by the pressure applied from the back pressure chamber 100 so that the radial outer side of the valve seat portion 48 covers the valve disk 53. The damping valve 91 and the back pressure chamber 100 constitute a part of the first damping force generating mechanism 41. The back pressure chamber 100 is constantly in communication with the passage in the groove portion 30 of the piston rod 21 via a passage in the passage groove 79 of the pilot case 62 .

[0052] The disc valve 99 separates from the valve seat portion 75 to communicate between the back pressure chamber 100 and the cylinder chamber 20. At that time, the disc valve 99 restricts the flow of the oil L between the valve seat portion 75 and the disc valve 99. The disc valve 99 and the valve seat portion 75 constitute a second damping force generating mechanism 110. When the disc valve 99 is separated from the valve seat portion 75, the second damping force generating mechanism 110 connects the back pressure chamber 100 and the cylinder chamber 20. At that time, the second damping force generating mechanism 110 suppresses the flow of oil L between the back pressure chamber 100 and the cylinder chamber 20 to generate a damping force.

[0053] 2 to the cylinder chamber 20 via the passages in the multiple passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81 of the disc 50, the passage in the groove portion 30 of the piston rod 21, the passage in the passage groove 79 of the pilot case 62, the back pressure chamber 100, and the passage between the disc valve 99 and the valve seat portion 75. The second damping force generating mechanism 110 is an extension-side damping force generating mechanism that generates a damping force by suppressing the flow of the oil L from the back pressure chamber 100 to the cylinder chamber 20 during the extension stroke.

[0054] The passages in the passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81 of the disk 50, the passage in the groove portion 30 of the piston rod 21, the passage in the passage groove 79 of the pilot case 62, the back pressure chamber 100, and the passage between the disk valve 99 and the valve seat portion 75 constitute a second passage 102. The second damping force generating mechanism 110 is provided in the second passage 102. In the second passage 102, the passages in the passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81, the passage in the groove portion 30, the passage in the passage groove 79, and the back pressure chamber 100 are always in communication with the cylinder chamber 19. The second passage 102 is a passage through which the oil L flows from the cylinder chamber 19, which is the upstream side, to the cylinder chamber 20, which is the downstream side, by the movement of the piston 18 in the extension stroke among the cylinder chambers 19 and 20.

[0055] In the second passage 102, the passage hole 37 of the piston 18 and the passage groove 38 are common to the first passage 43. In the second passage 102, the passage in the notch 81 of the disk 50, the passage in the groove portion 30 of the piston rod 21, the passage in the passage groove 79 of the pilot case 62, the back pressure chamber 100, and the passage between the disk valve 99 and the valve seat portion 75 are provided in parallel with the passage between the damping valve 91 and the valve seat portion 48 in the first passage 43, so that the cylinder chamber 19 and the cylinder chamber 20 can be communicated with each other. The first damping force generating mechanism 41 on the extension side controls the opening of the damping valve 91 by the pressure of the oil L introduced into the back pressure chamber 100 of the second passage 102. The back pressure chamber 100 of the second passage 102 pressurizes the damping valve 91 of the first damping force generating mechanism 41 in the valve closing direction.

[0056] Here, it is also possible to provide a fixed orifice in the second passage 102 between the disc valve 99 and the valve seat portion 75, which constantly connects the second passage 102 to the cylinder chamber 20. For this reason, the second passage 102 only needs to be a passage through which the oil L flows out from at least one of the cylinder chambers 19, 20 due to the movement of the piston 18.

[0057] As shown in Fig. 2, on the valve seat portion 49 side of the piston 18 in the axial direction, there are provided, in order from the piston 18 side in the axial direction of the piston 18, one disk 111, a plurality of (specifically, nine) disks 112, one disk 113, one disk 114, and one circular ring member 115. The disks 111-114 and the circular ring member 115 are all made of metal. The disks 111-114 and the circular ring member 115 are all in the form of a circular flat plate with holes of a constant thickness. The mounting shaft portion 28 of the piston rod 21 is fitted inside each of the disks 111-114 and the circular ring member 115.

[0058] The disk 111 abuts against a portion of the piston 18 that is radially inward of the passage groove 40 . Of the multiple discs 112, the disc 112 closest to the piston 18 in the axial direction abuts against the valve seat portion 49 of the piston 18. The multiple discs 112 open and close the opening of the first passage 44 formed in the piston 18 by moving away from and abutting against the valve seat portion 49.

[0059] The multiple discs 112 constitute a disc valve 122. The disc valve 122 can be seated on and removed from the valve seat portion 49. A first passage 44 is formed between the disc valve 122 and the valve seat portion 49 of the piston 18. When the disc valve 122 is released from the valve seat portion 49, the first passage 44 is opened, and the first passage 44 is opened to the cylinder chamber 19. When the disc valve 122 is released from the valve seat portion 49 of the piston 18 and opened, the oil L from the first passage 44 flows into the cylinder chamber 19. At that time, the disc valve 122 suppresses the flow of the oil L between the disc valve 122 and the valve seat portion 49. Therefore, the disc valve 122 suppresses the flow of the oil L from the cylinder chamber 20 to the cylinder chamber 19 via the first passage 44.

[0060] The disc valve 122 and the valve seat portion 49 constitute the first damping force generating mechanism 42 on the compression side. The disc valve 122 is formed with a fixed orifice 123 that connects the first passage 44 to the cylinder chamber 19 even when the disc valve 122 is in contact with the valve seat portion 49. The fixed orifice 123 constitutes the first passage 44, and constitutes the first damping force generating mechanism 42. It is also possible to configure the first passage 44 without providing the fixed orifice 123. For this reason, the first passage 44 only needs to be a passage through which the oil L flows out of at least one of the cylinder chambers 19, 20 due to the movement of the piston 18.

[0061] The disk 113 has an outer diameter smaller than the minimum outer diameter of the disk valve 122 . The outer diameter of disc 114 is larger than the outer diameter of disc 113. Disc 114 and annular member 115 abut against disc valve 122 when disc valve 122 deforms in the opening direction, suppressing deformation of disc valve 122 in the opening direction beyond a specified limit. Annular member 115 abuts against shaft step portion 29 of piston rod 21.

[0062] A frequency sensitive mechanism 130 is provided on the axially opposite side of the disc 66 to the disc 65. The frequency sensitive mechanism 130 varies the damping force according to the frequency of the axial movement of the piston 18 (hereinafter referred to as the piston frequency).

[0063] As shown in Fig. 4, the frequency sensitive mechanism 130 has one case member 131 on the side of the disk 66 in the axial direction. The frequency sensitive mechanism 130 has a plurality of (specifically, three) disks 132 having the same outer diameter and inner diameter, and one valve member 133, on the opposite side of the disk 66 in the axial direction of the case member 131. The frequency sensitive mechanism 130 has, on the opposite side of the disk 66 in the axial direction of the disk 132 and the valve member 133, in order from the disk 132 and valve member 133 side to the disk 66, one flexible member 135, one disk 136, one stopper disk 137, a plurality of (specifically, two) stopper disks 138 having the same outer diameter and inner diameter, a plurality of (specifically, two) stopper disks 139 having the same outer diameter and inner diameter, and a plurality of (specifically, two) disks 140 having the same outer diameter and inner diameter. A circular ring member 141 is provided on the axially opposite side of disk 140 from stopper disk 139. Stopper disk 137, the plurality of stopper disks 138, and the plurality of stopper disks 139 form a stopper 142. The plurality of disks 140 form a support member 143.

[0064] The case member 131, the disks 132, 136, 140, the flexible member 135, the stopper disks 137-139, and the annular member 141 are all made of metal. The disks 132, 136, 140, the flexible member 135, the stopper disks 137-139, and the annular member 141 are all circular flat plates with holes of a certain thickness. In other words, the disks 132, 136, 140, the flexible member 135, the stopper disks 137-139, and the annular member 141 are all formed from annular plate-like members. The disks 132, 136, 140, the valve member 133, the flexible member 135, the stopper disks 137-139, and the annular member 141 are all disposed radially inward of the case member 131. The mounting shaft portion 28 of the piston rod 21 is fitted inside the case member 131, the disks 132, 136, 140, the flexible member 135, the stopper disks 137-139, and the annular member 141. As a result, the central axis of the case member 131, the disks 132, 136, 140, the flexible member 135, the stopper disks 137-139, and the annular member 141 coincides with that of the piston rod 21. The mounting shaft portion 28 of the piston rod 21 and the disks 132 are inserted into the inner periphery of the valve member 133 with radial gaps. In the frequency sensitive mechanism 130, the case member 131, the disks 132, 136, 140, the flexible member 135, and the stopper disks 137-139 form a valve case 145. The frequency sensitive mechanism 130 has a valve member 133 inside the valve case 145 .

[0065] The case member 131 is cylindrical and has a bottom. A through hole 155 is formed in the radial center of the case member 131, penetrating the case member 131 in the axial direction. As shown in Fig. 2, the through hole 155 has a smaller diameter on the piston 18 side in the axial direction than on the opposite side to the piston 18, and the mounting shaft portion 28 of the piston rod 21 is fitted into this smaller diameter portion.

[0066] As shown in FIG. 4, the case member 131 has a bottom portion 150, a protruding portion 151, a cylindrical portion 153, and a sheet portion 154. The bottom portion 150 is a circular plate having a hole. The width of the bottom portion 150 in the radial direction is constant over the entire circumference. A through hole 155 is formed in the bottom portion 150. The protruding portion 151 is annular. The protruding portion 151 protrudes from the inner peripheral edge of the bottom portion 150 in the axial direction of the bottom portion 150 toward the opposite side to the disk 66. A passage groove 158 is formed in the protruding portion 151, penetrating the protruding portion 151 in the radial direction. The passage in the passage groove 158 communicates with the passage in the groove portion 30 of the piston rod 21.

[0067] The cylindrical portion 153 is cylindrical with an inner diameter larger than the outer diameter of the protruding portion 151. The cylindrical portion 153 extends from the outer peripheral edge of the bottom portion 150 along the axial direction of the bottom portion 150 on the same side as the protruding portion 151. The cylindrical portion 153 has, on its inner peripheral side, a small diameter portion 161, a first inclined portion 162, a large diameter portion 163, a second inclined portion 164, and an open end portion 165, in that order from the bottom portion 150 side in the axial direction. The small diameter portion 161, the first inclined portion 162, the large diameter portion 163, the second inclined portion 164, and the open end portion 165 are aligned with each other along their central axes.

[0068] The small diameter portion 161 is located on the bottom portion 150 side in the axial direction of the cylindrical portion 153. The small diameter portion 161 has an inner peripheral surface that is cylindrical. The first inclined portion 162 extends in the opposite direction to the bottom portion 150 from an end portion of the small diameter portion 161 opposite to the bottom portion 150 in the axial direction. The inner diameter of the inner circumferential surface of the first inclined portion 162 becomes larger on the side opposite to the bottom portion 150 in the axial direction of the cylindrical portion 153. In other words, the first inclined portion 162 extends while expanding in diameter on the side opposite to the bottom portion 150 in the axial direction of the cylindrical portion 153. The first inclined portion 162 is tapered.

[0069] The large diameter portion 163 extends in the opposite direction to the bottom portion 150 from an end portion of the first inclined portion 162 opposite to the bottom portion 150 in the axial direction. The large diameter portion 163 has an inner peripheral surface that is cylindrical. The large diameter portion 163 is formed to have an inner diameter larger than that of the small diameter portion 161. The axial length of the large diameter portion 163 is shorter than the axial length of the small diameter portion 161. The first inclined portion 162 is provided between the small diameter portion 161 and the large diameter portion 163 in the axial direction of the tubular portion 153.

[0070] The second inclined portion 164 extends in the opposite direction to the bottom portion 150 from an end portion of the large diameter portion 163 opposite to the bottom portion 150 in the axial direction. The inner diameter of the inner circumferential surface of the second inclined portion 164 becomes larger toward the opposite side to the bottom portion 150 in the axial direction of the cylindrical portion 153. In other words, the second inclined portion 164 extends while expanding in diameter toward the opposite side to the bottom portion 150 in the axial direction of the cylindrical portion 153. In further words, the second inclined portion 164 is inclined so that the inner diameter becomes smaller toward the bottom portion 150 side in the axial direction of the cylindrical portion 153. The second inclined portion 164 is on the opposite side to the bottom portion 150 of the large diameter portion 163 in the axial direction of the cylindrical portion 153. The second inclined portion 164 has an R-chamfered shape.

[0071] The open end 165 extends in the opposite direction to the bottom 150 from the end of the second inclined portion 164 opposite to the bottom 150 in the axial direction. The open end 165 is at the end of the tubular portion 153 opposite to the bottom 150 in the axial direction. The open end 165 has an inner circumferential surface that is cylindrical. The open end 165 is formed with an inner diameter larger than that of the large diameter portion 163. The axial length of the open end 165 is shorter than the axial length of the large diameter portion 163.

[0072] As described above, the cylindrical portion 153 extends from the bottom 150 and includes a small diameter portion 161 located on the bottom 150 side and having a small inner diameter, and a large diameter portion 163 located on the opposite side of the bottom 150 from the small diameter portion 161 and having a larger inner diameter than the small diameter portion 161. The cylindrical portion 153 also includes a first inclined portion 162 between the small diameter portion 161 and the large diameter portion 163, which is inclined so as to connect the small diameter portion 161 and the large diameter portion 163. The cylindrical portion 153 also includes a second inclined portion 164 located on the opposite side of the bottom 150 from the large diameter portion 163, which is inclined so that the inner diameter becomes smaller toward the bottom 150 side.

[0073] The outer diameter of the disk 132 is constant over the entire circumference, and the radial width of the disk 132 is constant over the entire circumference. The outer diameter of the disk 132 is slightly smaller than the outer diameter of the end face of the protrusion 151 on the axial side opposite the bottom portion 150. The flexible member 135 has a constant outer diameter over its entire circumference, and a constant radial width over its entire circumference. The flexible member 135 has an outer diameter that is larger than the outer diameter of the disk 132. Disk 136 has a constant outer diameter and a constant radial width over its entire circumference. The outer diameter of disk 136 is smaller than the outer diameter of flexible member 135 and smaller than the outer diameter of disk 132.

[0074] The stopper disk 137 has a constant outer diameter over its entire circumference and a constant radial width over its entire circumference. The outer diameter of the stopper disk 137 is larger than the outer diameter of the disk 136 and is equal to the outer diameter of the flexible member 135. The stopper disc 138 has a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The outer diameter of the stopper disc 138 is larger than the outer diameter of the stopper disc 137. The stopper disc 139 has a constant outer diameter over its entire circumference and a constant radial width over its entire circumference. The outer diameter of the stopper disc 139 is larger than the outer diameter of the stopper disc 138.

[0075] The stopper 142 is composed of the stopper disks 137 to 139 as described above. In other words, the stopper 142 has a plurality of stopper disks 137 to 139 each formed of an annular plate-like member. The stopper disks 137 and 138 are formed such that the outer diameter of the stopper disk 138 provided on the opposite side to the flexible member 135 is larger than the outer diameter of the stopper disk 137 provided on the flexible member 135 side in the axial direction of the case member 131. The stopper disks 138 and 139 are formed such that the outer diameter of the stopper disk 139 provided on the opposite side to the flexible member 135 is larger than the outer diameter of the stopper disk 138 provided on the flexible member 135 side in the axial direction of the case member 131.

[0076] The outer diameter of the disk 140 constituting the support member 143 is constant over its entire circumference, and the radial width of the disk 140 is constant over its entire circumference. The outer diameter of the disk 140 is larger than the outer diameter of the stopper disk 139.

[0077] The disks 132, 136, 140, the valve member 133, the flexible member 135, the stopper disks 137-139, and the annular member 141 are all disposed radially inside the cylindrical portion 153. In other words, the outer diameters of the disks 132, 136, 140, the valve member 133, the flexible member 135, the stopper disks 137-139, and the annular member 141 are all smaller than the inner diameters of the portions where they overlap in the axial direction of the cylindrical portion 153. The disks 132, 136, 140, the valve member 133, the flexible member 135, and the stopper disks 137-139 are all disposed within the range of the cylindrical portion 153 in the axial direction of the cylindrical portion 153. A portion of the circular ring member 141 is positioned within the range of the cylindrical portion 153 in the axial direction of the cylindrical portion 153, and the remaining portion is positioned outside the range of the cylindrical portion 153 in the axial direction of the cylindrical portion 153.

[0078] The disks 132, 136, the stopper disks 137-139, and the flexible member 135 are disposed within the range of the small diameter portion 161 in the axial direction of the cylindrical portion 153. The disks 132, 136, the stopper disks 137-139, and the flexible member 135 all have an outer diameter smaller than the inner diameter of the small diameter portion 161.

[0079] Support member 143 consisting of multiple discs 140 is positioned to overlap small diameter portion 161, first inclined portion 162, and large diameter portion 163 in the axial direction of cylindrical portion 153. The outer diameter of discs 140, i.e., support member 143, is smaller than the inner diameter of small diameter portion 161. In the axial direction of cylindrical portion 153, first inclined portion 162 is provided within the range of support member 143 over its entire length.

[0080] The circular ring member 141 overlaps with the large diameter portion 163, the second inclined portion 164, and the open end 165 in the axial direction of the tubular portion 153. The outer diameter of the circular ring member 141 is smaller than the inner diameter of the large diameter portion 163. In the axial direction of the tubular portion 153, the second inclined portion 164 and the open end 165 are provided within the range of the circular ring member 141 over their entire length.

[0081] The seat portion 154 is annular. The seat portion 154 protrudes from a position between the protruding portion 151 and the cylindrical portion 153 in the radial direction of the bottom portion 150 to the same side as the protruding portion 151 and the cylindrical portion 153 along the axial direction of the bottom portion 150. A notch 168 is formed at the tip of the protruding side of the seat portion 154, penetrating the tip in the radial direction of the seat portion 154. A plurality of notches 168 are formed at intervals in the circumferential direction of the seat portion 154 in the seat portion 154. Thus, the tip of the protruding side of the seat portion 154 is intermittently cut out in the circumferential direction of the seat portion 154. The protruding height of the seat portion 154 from the bottom portion 150 in the axial direction of the bottom portion 150 is greater than the protruding height of the protruding portion 151 from the bottom portion 150.

[0082] The valve member 133 is made up of a valve disc 171 and an elastic seal member 172. The valve member 133 is disposed between the cylindrical portion 153 of the case member 131 and the multiple discs 132 in the radial direction. The valve disc 171 is made of metal. The valve disc 171 is a circular flat plate with holes of a constant thickness. The valve disc 171 has a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The mounting shaft portion 28 of the piston rod 21 and the multiple discs 132 are inserted into the inner circumference of the valve disc 171. The valve disc 171 is elastically deformable, that is, flexible. The valve disc 171 has an inner diameter that allows the multiple discs 132 to be arranged inside with radial gaps. In other words, the inner diameter of the valve disc 171 is larger than the outer diameters of the multiple discs 132. The outer diameter of the valve disc 171 is smaller than the inner diameter of the small diameter portion 161 of the cylindrical portion 153. The valve disc 171 is thinner than the total thickness of all the discs 132.

[0083] The elastic seal member 172 is made of rubber and has a circular shape. The elastic seal member 172 is bonded to the outer periphery of the valve disc 171. The elastic seal member 172 is baked onto the valve disc 171 and is provided integrally with the valve disc 171. The elastic seal member 172 has a seal portion 173 and a biasing portion 174 . The seal portion 173 is annular, and is fixed over the entire outer periphery of the outer periphery of the valve disc 171. The seal portion 173 protrudes from the valve disc 171 towards the bottom 150 of the case member 131 in the axial direction of the valve member 133.

[0084] The urging portion 174 is annular and protrudes from the valve disc 171 to the opposite side to the bottom portion 150 in the axial direction of the valve member 133. The urging portion 174 is fixed to the outer periphery of the valve disc 171. The seal portion 173 and the urging portion 174 are connected to each other on the outer periphery of the valve disc 171 to be integrated. The urging portion 174 has a smaller outer diameter and a larger inner diameter as it moves away from the valve disc 171 in the axial direction. As a result, the cross-sectional shape of the urging portion 174 on a plane including the central axis is a tapered mountain shape that becomes thinner as it moves away from the valve disc 171 in the axial direction. The urging portion 174 has a notch 175 formed at the tip of the protruding side, which penetrates the tip in the radial direction of the urging portion 174. The urging portion 174 has a plurality of notches 175 formed at intervals in the circumferential direction of the urging portion 174. Therefore, the tip end of the urging portion 174 on the protruding side is intermittently cut out in the circumferential direction of the urging portion 174.

[0085] As described above, there is a radial gap between the valve member 133 and the multiple disks 132. The valve member 133 is press-fitted at its seal portion 173 into the small diameter portion 161 of the cylindrical portion 153 of the case member 131. This press-fitting centers the valve member 133 so that it is coaxially disposed with respect to the case member 131, the multiple disks 132, and the piston rod 21. At that time, the seal portion 173 of the valve member 133 abuts against the small diameter portion 161 over the entire circumference with a radial interference.

[0086] The seal portion 173 has a cylindrical base portion 176 and an annular protrusion portion 177. The seal portion 173 is bonded to the valve disc 171 at the base portion 176 and is connected to the biasing portion 174. The protrusion portion 177 protrudes from an intermediate position in the axial direction of the base portion 176 to the outside in the radial direction of the base portion 176. When the elastic seal member 172, including the protrusion portion 177, is in a natural state without being deformed as a whole, the outer diameter of the base portion 176 is smaller than the inner diameter of the small diameter portion 161. Furthermore, when the elastic seal member 172 is in a natural state as a whole in this manner, the outer diameter of the protrusion portion 177 is larger than the inner diameter of the small diameter portion 161 and smaller than the inner diameter of the large diameter portion 163.

[0087] The valve member 133 is press-fitted at its seal portion 173 into the small diameter portion 161 of the cylindrical portion 153 of the case member 131. Then, the seal portion 173, mainly the protrusion portion 177, elastically deforms radially inward and comes into close contact with the small diameter portion 161 over the entire circumference. As a result, the seal portion 173 fits liquid-tightly into the small diameter portion 161 of the cylindrical portion 153 of the case member 131 over the entire circumference.

[0088] The seal portion 173 is slidable in the axial direction of the cylindrical portion 153 relative to the cylindrical portion 153. At that time, the seal portion 173 slides in the axial direction of the cylindrical portion 153 relative to the small diameter portion 161 while maintaining a state in which the protrusion portion 177 is in close contact with the small diameter portion 161 over the entire circumference. As a result, the protrusion portion 177 of the seal portion 173 of the elastic seal member 172 constantly seals the gap between the valve member 133 and the cylindrical portion 153. The cylindrical portion 153 is provided with a small diameter portion 161 in the sliding range of the protrusion portion 177 of the valve member 133. The cylindrical portion 153 is provided with a first inclined portion 162, a large diameter portion 163, a second inclined portion 164, and an opening end portion 165, which serve as a guide section for assembling the valve member 133, outside the small diameter portion 161, which is the sliding range of the protrusion portion 177. Of these, the large diameter portion 163, the second inclined portion 164 and the open end 165 all have inner diameters larger than the outer diameter of the protrusion portion 177 of the valve member 133 in its natural state. The seal portion 173 is located radially outward of the seat portion 154 of the case member 131. The valve member 133 has a valve disc 171 that seats on the seat portion 154.

[0089] The flexible member 135 has an outer diameter larger than the inner diameter of the valve member 133, i.e., the inner diameter of the valve disc 171. The flexible member 135 is disposed on the opposite side of the valve disc 171 from the bottom portion 150 in the axial direction, and is pressed against the first support portion 178 on the inner periphery of the valve disc 171 over its entire periphery. This closes the gap between the flexible member 135 and the valve disc 171, i.e., the valve member 133.

[0090] As described above, the valve member 133 is centered relative to the valve case 145 by the seal portion 173 coming into contact with the cylindrical portion 153 over the entire circumference. In this state, the first support portion 178 on the inner circumferential side of the valve disc 171 of the valve member 133 is disposed between the protruding portion 151 and the flexible member 135 in the axial direction. The first support portion 178 has one side opposite to the bottom portion 150 in the axial direction in contact with the flexible member 135 and is supported by the flexible member 135. In other words, the valve member 133 has the first support portion 178 whose one radially inner side side is supported by the flexible member 135. The first support portion 178 is not clamped from both sides and is supported by the flexible member 135 only on one side. The first support portion 178 on the inner circumferential side of the valve disc 171 of the valve member 133 is movable between the protruding portion 151 and the flexible member 135 within the range of the entire axial length of the multiple (specifically, three) discs 132.

[0091] The valve member 133 has a second support portion 179, which is arranged radially outward from the first support portion 178 of the valve disc 171, in contact with and supported by the seat portion 154 at one side surface on the bottom portion 150 side in the axial direction. In other words, the valve member 133 has the second support portion 179, which is arranged radially outward from the first support portion 178 and has one side surface supported by the seat portion 154. The second support portion 179 is not clamped from both sides and is supported by the seat portion 154 on only one side. Therefore, the valve member 133 has a simply supported structure in which one surface side of a first support portion 178 of the valve disc 171 is supported by the flexible member 135, and the other surface side of a second support portion 179 radially outward of the first support portion 178 of the valve disc 171 is supported by the seat portion 154. In other words, the valve disc 171 is not clamped in the axial direction.

[0092] In the valve member 133, the biasing portion 174 is disposed on the opposite side of the bottom portion 150 in the axial direction of the valve member 133. A portion of the biasing portion 174 is disposed radially outward of the second support portion 179. The biasing portion 174 abuts against the support member 143 made of a plurality of disks 140 at a portion disposed radially outward of the second support portion 179. The biasing portion 174 biases the second support portion 179 side in the radial direction of the valve member 133 toward the seat portion 154 side in the axial direction of the valve member 133. The biasing portion 174 may be entirely disposed radially outward of the second support portion 179. That is, in the valve member 133, it is sufficient that at least a portion of the biasing portion 174 is disposed radially outward of the second support portion 179.

[0093] The valve member 133 is generally in the shape of a circular ring plate, and is generally elastically deformable, i.e., flexible. The valve member 133 is flexible such that the second support portion 179 moves away from the seat portion 154 while the first support portion 178 maintains a state of contact with the flexible member 135. When the valve member 133 is flexible in this manner, the valve member 133 is flexible such that the second support portion 179 moves toward the opposite side from the bottom portion 150 in the axial direction of the case member 131 relative to the first support portion 178. The outer diameter of the flexible member 135 is larger than the outer diameter of the disk 136 that abuts against the side surface opposite to the first support portion 178 in the axial direction. Therefore, the flexible member 135 is flexible in the axial direction of the case member 131 in a direction away from the bottom portion 150. The valve member 133 is flexible so that the second support portion 179 moves away from the seat portion 154 while the first support portion 178 remains in contact with the flexible member 135 .

[0094] The flexible member 135 is flexible together with the valve member 133. The flexible member 135 is thinner than the valve disc 171 of the valve member 133, and is less rigid than the valve disc 171, making it easier to bend. The flexible member 135 is flexible in the opposite direction to the bottom 150 due to movement and deformation in the axial direction of the valve member 133 toward the opposite side to the seat portion 154. The stopper 142 consisting of the stopper discs 137 to 139 suppresses the amount of bending of the flexible member 135 by the stopper disc 137 abutting against the bending flexible member 135. Here, the valve member 133 is flexible so as to move the second support portion 179 further toward the opposite side to the bottom 150 than the first support portion 178 in the axial direction of the case member 131, even if the bending of the flexible member 135 is suppressed by the stopper 142.

[0095] The multiple discs 140 have an outer diameter larger than the outer diameter of the stopper disc 139 and smaller than the inner diameter of the cylindrical portion 153. The inner circumferential side of the support member 143 made up of the multiple discs 140 abuts against the stopper disc 139 and the annular member 141, and the outer circumferential side abuts against the biasing portion 174 of the valve member 133. The support member 143 suppresses movement of the valve member 133 in the axial direction opposite to the bottom portion 150.

[0096] The seat portion 154 of the case member 131 supports the second support portion 179 of the valve disc 171 of the valve member 133 from one axial side. The flexible member 135 supports the first support portion 178, which is located more inward than the seat portion 154 of the valve disc 171, from the other axial side. The shortest axial distance between the seat portion 154 and the flexible member 135 is slightly smaller than the axial thickness of the valve disc 171. Therefore, the valve disc 171 is pressed against both the seat portion 154 and the flexible member 135 by its own elastic force in a slightly elastically deformed state.

[0097] The valve member 133 is provided in the case member 131 and divides the inside of the case member 131 into a first chamber 181 and a second chamber 182. The first chamber 181 is between the bottom 150 and the valve member 133 in the axial direction of the case member 131. In other words, the first chamber 181 is closer to the bottom 150 than the valve member 133 in the axial direction of the case member 131. The second chamber 182 is between the valve member 133 and the support member 143 in the axial direction of the case member 131. The support member 143 is provided in the second chamber 182 so as to form the second chamber 182. The second chamber 182 is on the opposite side to the bottom 150 than the valve member 133 in the axial direction of the case member 131, i.e., on the opening side of the case member 131.

[0098] The first chamber 181 and the second chamber 182 are both variable in volume, and the volume changes with the movement and deformation of the valve member 133. The first chamber 181 is always in communication with the passage in the groove portion 30 of the piston rod 21 through a passage in the passage groove 158 of the case member 131. The first chamber 181 is always in communication with the cylinder chamber 19 through the passage in the passage groove 158, the passage in the groove portion 30, the passage in the notch 81 shown in FIG. 2, the passage groove 38 of the first passage 43, and the passages in the multiple passage holes 37. The first chamber 181 is always in communication with the back pressure chamber 100 through the passage in the passage groove 158 shown in FIG. 4, the passage in the groove portion 30, and the passage in the passage groove 79 shown in FIG. 3. The second chamber 182 is always in communication with the cylinder chamber 20 through a passage portion 185 between the support member 143 and the cylindrical portion 153 of the case member 131.

[0099] During the extension stroke, the oil L from the cylinder chamber 19 shown in Fig. 2 is introduced into the first chamber 181 through the passages in the multiple passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81 of the disc 50, the passage in the groove portion 30 of the piston rod 21, and the passage in the passage groove 158 of the case member 131 shown in Fig. 4. Then, the valve disc 171 of the valve member 133 bends the flexible member 135 that abuts on the first support portion 178 in a direction away from the bottom portion 150 in the axial direction of the case member 131, that is, in the direction of the stopper disc 137. At the same time, the valve disc 171 compresses and deforms the biasing portion 174 that abuts on the support member 143 in the axial direction of the case member 131 between the support member 143. At the same time, the valve disc 171 bends in a tapered manner, with the contact point with the flexible member 135 as a fulcrum, so that the second support portion 179 is further away from the bottom portion 150 in the axial direction of the case member 131 than the first support portion 178. In this way, the valve disc 171 bends, with the contact point with the flexible member 135 as a fulcrum, so that the second support portion 179 is further away from the bottom portion 150 in the axial direction of the case member 131 than the first support portion 178.

[0100] As the introduction of oil liquid L into first chamber 181 progresses further, bending of flexible member 135 in contact with valve disc 171 is restricted by abutting stopper disc 137 of stopper 142. Then, valve disc 171 bends in a tapered shape with the contact point with flexible member 135 as a fulcrum so that second support portion 179 is further separated from bottom 150 in the axial direction of case member 131 than first support portion 178, while further compressively deforming biasing portion 174 between support member 143 and valve disc 171 in the axial direction of case member 131.

[0101] Due to the above-mentioned movement and deformation of the valve disc 171, the valve member 133 increases the volume of the first chamber 181. Here, when the valve disc 171 deforms in this manner, the volume of the second chamber 182 decreases. At that time, the oil L in the second chamber 182 flows into the cylinder chamber 20 via the passage portion 185.

[0102] As shown in FIG. 2, the passages in the passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81, the passage in the groove portion 30 of the piston rod 21, the passage in the passage groove 158, the first chamber 181, the second chamber 182, and the passage portion 185 constitute a third passage 191. In the third passage 191, the passages in the passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81, the passage in the groove portion 30, the passage in the passage groove 158, and the first chamber 181 are always in communication with the cylinder chamber 19. In the third passage 191, the passage portion 185 and the second chamber 182 are always in communication with the cylinder chamber 20. The third passage 191 is a passage through which the oil L moves from the cylinder chamber 19, which is the upstream side, to the cylinder chamber 20, which is the downstream side, during the extension stroke. The third passage 191 is a passage through which the oil L moves from the cylinder chamber 20 on the upstream side to the cylinder chamber 19 on the downstream side during the compression stroke. The frequency sensitive mechanism 130 has a valve member 133 provided in the third passage 191.

[0103] In the third passage 191, the passage hole 37 and the passage groove 38 of the piston 18 are common to the first passage 43. In the third passage 191, the passage in the notch 81 of the disk 50, the passage in the groove portion 30 of the piston rod 21, the passage in the passage groove 158, the first chamber 181, the second chamber 182, and the passage portion 185 are provided in parallel with the passage between the damping valve 91 and the valve seat portion 48 in the first passage 43, and the cylinder chamber 19 and the cylinder chamber 20 can be communicated with each other.

[0104] The valve member 133 is capable of moving a first support portion 178 (shown in FIG. 4) on the inner circumferential side of the valve disc 171 toward the bottom portion 150 in the axial direction between the case member 131 and the flexible member 135. The valve member 133 is capable of moving a first support portion 178 of the valve disc 171 toward the bottom portion 150 in the axial direction while bending the flexible member 135 until the bending of the flexible member 135 is suppressed by the stopper 142. When the first support portion 178 of the valve disc 171 is in contact with the flexible member 135 over the entire circumference, the valve member 133 blocks the flow of the oil L between the first chamber 181 and the second chamber 182. When the first support portion 178 of the valve disc 171 is separated from the flexible member 135 in the axial direction, the valve member 133 allows the flow of the oil L between the second chamber 182 and the first chamber 181. The first support portion 178 of the valve disc 171 and the flexible member 135 constitute a check valve 193. The check valve 193 is provided in the third passage 191.

[0105] The check valve 193 restricts the flow of hydraulic fluid L from the first chamber 181 to the second chamber 182 through the third passage 191, while allowing the flow of hydraulic fluid L from the second chamber 182 to the first chamber 181 through the third passage 191. The check valve 193 blocks communication between the cylinder chamber 19 and the cylinder chamber 20 through the third passage 191 during an extension stroke in which the pressure in the cylinder chamber 19 becomes higher than the pressure in the cylinder chamber 20. The check valve 193 connects the cylinder chamber 20 to the cylinder chamber 19 through the third passage 191 during a compression stroke in which the pressure in the cylinder chamber 20 becomes higher than the pressure in the cylinder chamber 19. In this way, the third passage 191 connects the cylinder chamber 20 to the cylinder chamber 19 by opening the check valve 193.

[0106] As shown in FIG. 2, the piston rod 21 has the circular ring member 115, the disk 114, the disk 113, the multiple disks 112, the disk 111 and the piston 18 stacked in this order on the shaft step portion 29 with the mounting shaft portion 28 inserted into the inside of each. 3, from this state, with the mounting shaft portion 28 inserted inside, the disc 50, disc 51, valve disc 52, the multiple valve discs 53, pilot valve 60, disc 61, pilot case 62, disc 63, the multiple discs 64, disc 65 and disc 66 are placed on the piston 18 in this order. At this time, the pilot case 62 fits the seal member 86 of the pilot valve 60 into the outer cylindrical portion 73.

[0107] 4, from this state, with the mounting shaft portion 28 and the plurality of discs 132 inserted inside, the case member 131 and the plurality of discs 132 are placed on the discs 66 in this order. Furthermore, from this state, with the mounting shaft portion 28 and the multiple disks 132 inserted inside, the valve member 133 is placed on the seat portion 154 of the case member 131. At this time, the elastic seal member 172 of the valve member 133 is fitted into the cylindrical portion 153 of the case member 131. Furthermore, with the mounting shaft portion 28 inserted into the inside of each, the flexible member 135, the disk 136, the stopper disk 137, the multiple stopper disks 138, the multiple stopper disks 139, the multiple disks 140 and the circular member 141 are stacked in this order on the disk 132 and the valve disk 171 of the valve member 133.

[0108] As shown in FIG. 2, in a state where the components from the circular member 115 to the circular member 141 are arranged on the piston rod 21 as described above, a nut 195 is screwed onto the threaded portion 31 of the mounting shaft portion 28 protruding beyond the circular member 141. As a result, the inner circumferential sides or the entirety of the components from the circular member 115 to the circular member 141 are sandwiched between the shaft step portion 29 of the piston rod 21 and the nut 195 and clamped in the axial direction. At that time, the valve member 133, including its inner circumferential side, is not clamped in the axial direction. In this state, as shown in FIG. 4, the first support portion 178 of the valve disc 171 abuts against the flexible member 135, the second support portion 179 abuts against the seat portion 154 of the case member 131, and the biasing portion 174 of the elastic seal member 172 abuts against the support member 143.

[0109] As described above, the inner circumferential sides or the entirety of each of the parts from the circular member 115 to the circular member 141 are sandwiched between the shaft step portion 29 of the piston rod 21 and the nut 195 and clamped in the axial direction. In this state, as shown in Fig. 3, the pilot valve 60 is fixed to the piston rod 21 by having the radially inner portion of the pilot disc 85, which is its radially inner side, sandwiched together with the discs 50, 51 and the valve discs 52, 53 from both axial sides by the inner seat 46 of the piston 18 and the disc 61. Specifically, the portion of the pilot disc 85 that overlaps both the inner seat 46 of the piston 18 and the disc 61 in the radial direction of the pilot valve 60 is fixed to the piston rod 21, the inner seat 46, and the disc 61.

[0110] In this state, the discs 50, 51 and the valve discs 52, 53, together with the pilot disc 85 of the pilot valve 60, have their radially inner portions sandwiched between the inner seat 46 of the piston 18 and the disc 61 from both axial sides and fixed to the piston rod 21. Specifically, the discs 50, 51 and the valve discs 52, 53 have their radially overlapping portions that overlap both the inner seat 46 of the piston 18 and the disc 61, and fixed to the piston rod 21, the inner seat 46, and the disc 61.

[0111] In this state, the radially inner portions of all the valve discs 53, which are fixed to the piston rod 21, the inner seat 46, and the disc 61, form the fixed portions 201. The radially inner fixed portions 201 of the multiple valve discs 53 are fixed to the pilot disc 85 of the pilot valve 60 from both axial ends.

[0112] All the valve discs 53 have the same shape when viewed in the axial direction, and all of them have the shape shown in FIG.

[0113] The valve disc 53 has an inner peripheral end face 202 on the radial inside and an outer peripheral end face 203 (radially outer end face) on the radial outside. The inner peripheral end face 202 forms a cylindrical surface shape with a constant diameter over the entire circumference. The outer peripheral end face 203 forms a cylindrical surface shape with a constant diameter over the entire circumference. In other words, the outer peripheral end face 203 on the radial outside of the valve disc 53 is formed of an annular, specifically, an annular plate-like member. The inner peripheral end face 202 on the radial inside of the valve disc 53 is also formed of an annular, specifically, an annular plate-like member. The valve disc 53 has a predetermined range on the inner peripheral end face 202 side in the radial direction, including the inner peripheral end face 202, as the fixed portion 201 described above. The fixed portion 201 is an endless annular shape. The valve disc 53 has a predetermined range on the outer peripheral end face 203 side in the radial direction, including the outer peripheral end face 203, as the outer peripheral edge portion 204. The outer peripheral edge portion 204 is an endless circular ring shape. In other words, the outer peripheral edge portion 204 is also formed of a circular plate-shaped member.

[0114] The valve disc 53 has a plurality of, specifically six, first holes 205 (flexure promoting portions) and a plurality of, specifically twelve, second holes 206 (flexure promoting portions). All of the first holes 205 and all of the second holes 206 penetrate the valve disc 53 in the axial direction, i.e., the thickness direction. All of the first holes 205 are circular holes of the same diameter. All of the second holes 206 are circular holes of the same diameter. The inner diameter of the second holes 206 is larger than the inner diameter of the first holes 205. In other words, the second holes 206 are formed to have a larger diameter than the first holes 205.

[0115] All of the first holes 205 are disposed at equal intervals in the circumferential direction of the inner circumferential end face 202, i.e., in the circumferential direction of the valve disc 53. The centers of all of the first holes 205 are disposed at positions equidistant from the center of the inner circumferential end face 202, i.e., the center of the valve disc 53.

[0116] All of the second holes 206 are disposed at equal intervals in the circumferential direction of the outer circumferential end face 203, i.e., in the circumferential direction of the valve disc 53. The centers of all of the second holes 206 are disposed at positions equidistant from the center of the inner circumferential end face 202, i.e., the center of the valve disc 53. The distance between the center of the second holes 206 and the center of the valve disc 53 is longer than the distance between the center of the first hole 205 and the center of the valve disc 53. In other words, the second holes 206 are disposed outward of the first holes 205 in the radial direction of the valve disc 53.

[0117] The first hole 205 is disposed at a central position between adjacent second holes 206 in the circumferential direction of the valve disc 53. The valve disc 53 has twelve central positions between adjacent second holes 206 in the circumferential direction, the same as the second holes 206. In contrast, the first holes 205 have only half as many, six positions. Therefore, the valve disc 53 has the first holes 205 disposed at alternate central positions in the circumferential direction of the valve disc 53 among the central positions between adjacent second holes 206 in the circumferential direction of the valve disc 53.

[0118] All of the first holes 205 and all of the second holes 206 are arranged in a range outer than the fixed portion 201 in the radial direction of the valve disc 53, specifically, in a range in the radial direction between the fixed portion 201 and the outer circumferential edge portion 204. In other words, the valve disc 53 has a plurality of first holes 205 and a plurality of second holes 206 formed in a part radially outer than the fixed portion 201 and a part radially inner than the outer circumferential edge portion 204.

[0119] The valve disc 53 has an annular region in the vicinity of the fixed portion 201 where neither the first hole 205 nor the second hole 206 is formed. This region is the inner region 207. The inner region 207 is located outside the fixed portion 201 in the radial direction of the valve disc 53. In addition, the valve disc 53 has an annular region in which the plurality of first holes 205 are formed as an intermediate region 208. The intermediate region 208 is located outside the inner region 207 in the radial direction of the valve disc 53. In addition, the valve disc 53 has an annular region in which the plurality of second holes 206 are formed as an outer region 209. The outer region 209 is located outside the intermediate region 208 and inside the outer circumferential edge portion 204 in the radial direction of the valve disc 53.

[0120] The valve disc 53 has a lower axial rigidity in the intermediate region 208 in which the multiple first holes 205 are formed than in the inner region 207 in which neither the first hole 205 nor the second hole 206 is formed. Also, the valve disc 53 has a lower axial rigidity in the outer region 209 in which the multiple second holes 206, which are larger in diameter and more in number than the first holes 205, are formed than in the intermediate region 208 in which the multiple first holes 205 are formed. The valve disc 53 has a plurality of first holes 205 provided on the radially inner side to promote axial bending in the intermediate region 208, which is radially outer, than the inner region 207, which is radially inner. The valve disc 53 has a plurality of second holes 206 provided radially outer than the first holes 205 to promote axial bending in the outer region 209, which is radially outer, than the intermediate region 208, which is radially inner. The valve disc 53 is provided with a first hole 205 and a second hole 206 in a part radially outer than the fixed portion 201 and in a part radially inner than the outer circumferential edge portion 204 .

[0121] As shown in FIG. 1, the above-mentioned base valve 25 is provided between the bottom 12 of the outer cylinder 4 and the inner cylinder 3. The base valve 25 has a base valve member 221, a disk valve 222, a disk valve 223, and a mounting pin 224. The base valve 25 has the base valve member 221 placed on the bottom 12, and the base valve member 221 fitted into the inner cylinder 3. The base valve member 221 separates the cylinder chamber 20 and the reservoir chamber 6. The disk valve 222 is provided on the lower side of the base valve member 221, i.e., on the reservoir chamber 6 side. The disk valve 223 is provided on the upper side of the base valve member 221, i.e., on the cylinder chamber 20 side. The mounting pin 224 attaches the disk valve 222 and the disk valve 223 to the base valve member 221.

[0122] The base valve member 221 has an annular shape, and a mounting pin 224 is inserted through the center in the radial direction. The base valve member 221 is formed with a plurality of passage holes 225 and a plurality of passage holes 226. The plurality of passage holes 225 allow the oil L to flow between the cylinder chamber 20 and the reservoir chamber 6. The plurality of passage holes 226 are arranged outside the plurality of passage holes 225 in the radial direction of the base valve member 221. The plurality of passage holes 226 allow the oil L to flow between the cylinder chamber 20 and the reservoir chamber 6. The disk valve 222 on the reservoir chamber 6 side allows the oil L to flow from the cylinder chamber 20 to the reservoir chamber 6 via the passage hole 225. On the other hand, the disk valve 222 suppresses the flow of the oil L from the reservoir chamber 6 to the cylinder chamber 20 via the passage hole 225. The disc valve 223 allows the flow of the oil L from the reservoir chamber 6 to the cylinder chamber 20 via the passage hole 226. On the other hand, the disc valve 223 restricts the flow of the oil L from the cylinder chamber 20 to the reservoir chamber 6 via the passage hole 226.

[0123] The disc valve 222 and the base valve member 221 form a damping valve mechanism 227. The damping valve mechanism 227 opens during the compression stroke of the shock absorber 1 to allow oil L to flow from the cylinder chamber 20 to the reservoir chamber 6 and generate a damping force. The disc valve 223 and the base valve member 221 form a suction valve mechanism 228. The suction valve mechanism 228 opens during the extension stroke of the shock absorber 1 to allow oil L to flow from the reservoir chamber 6 into the cylinder chamber 20. The suction valve mechanism 228 mainly functions to allow oil L to flow from the reservoir chamber 6 to the cylinder chamber 20 without generating any damping force, so as to compensate for a shortage of oil caused by the extension of the piston rod 21 from the cylinder 2.

[0124] Next, the main operation of the shock absorber 1 will be described. "When it is assumed that the frequency sensitive mechanism 130 does not operate during the extension stroke, and only the first damping force generating mechanism 41 and the second damping force generating mechanism 110 on the extension side operate" In this case, when the moving speed of the piston 18 (hereinafter referred to as the piston speed) is slower than a first predetermined value, the oil L from the cylinder chamber 19 flows into the cylinder chamber 20 via the fixed orifice 92 of the first damping force generating mechanism 41 provided in the first passage 43 shown in Fig. 2. Therefore, a damping force with an orifice characteristic (the damping force is approximately proportional to the square of the piston speed) is generated. Therefore, the characteristic of the damping force with respect to the piston speed when the piston speed is slower than the first predetermined value is that the rate of increase of the damping force with respect to an increase in the piston speed is relatively high.

[0125] When the piston speed is equal to or greater than the first predetermined value and less than the second predetermined value, the oil L from the cylinder chamber 19 passes through the passages in the passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81, the passage in the groove portion 30, the passage in the passage groove 79, the back pressure chamber 100, and flows between the disc valve 99 and the valve seat portion 75 while opening the disc valve 99 of the second damping force generating mechanism 110, and into the cylinder chamber 20. Thus, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) is generated. Therefore, the characteristic of the damping force with respect to the piston speed when the piston speed is equal to or greater than the first predetermined value and less than the second predetermined value is that the rate of increase of the damping force with respect to the increase of the piston speed is lower than when the piston speed is less than the first predetermined value.

[0126] When the piston speed becomes faster than the second predetermined value, the relationship of the forces (hydraulic pressure) acting on the damping valve 91 of the first damping force generating mechanism 41 is such that the force in the opening direction applied from the passages in the passage holes 37 and the passage groove 38 of the first passage 43 becomes larger than the force in the closing direction applied from the back pressure chamber 100. Therefore, in this region, as the piston speed increases, the damping valve 91 opens away from the valve seat portion 48 of the piston 18. Therefore, the oil L from the cylinder chamber 19 flows from the first passage 43 through between the damping valve 91 and the valve seat portion 48 while opening the damping valve 91, in addition to the flow to the cylinder chamber 20 passing between the disc valve 99 and the valve seat portion 75 while opening the disc valve 99 as described above. Therefore, the increase rate of the damping force with respect to the increase in the piston speed when the piston speed is equal to or greater than the second predetermined value is lower than when the piston speed is equal to or greater than the first predetermined value and less than the second predetermined value.

[0127] "When it is assumed that the frequency sensitive mechanism 130 does not operate during the compression stroke and only the first damping force generating mechanism 42 on the compression side operates" In this case, when the piston speed is slower than the third predetermined value, the oil L from the cylinder chamber 20 flows into the cylinder chamber 19 via the first passage 44 and the fixed orifice 123 of the first damping force generating mechanism 42. This generates a damping force with orifice characteristics. Therefore, the characteristic of the damping force with respect to the piston speed when the piston speed is slower than the third predetermined value is that the rate of increase of the damping force with respect to an increase in the piston speed is relatively high.

[0128] When the piston speed becomes faster than the third predetermined value, the oil L introduced from the cylinder chamber 20 into the first passage 44 opens the disc valve 122 of the first damping force generating mechanism 42 and flows between the disc valve 122 and the valve seat portion 49 into the cylinder chamber 19. This generates a damping force with valve characteristics. For this reason, the characteristic of the damping force relative to the piston speed when the piston speed is equal to or greater than the third predetermined value is that the rate of increase of the damping force relative to an increase in the piston speed is lower than when the piston speed is less than the third predetermined value.

[0129] "When the frequency sensitive mechanism 130 acts during the extension stroke" In the first embodiment, the frequency sensitive mechanism 130 varies the damping force according to the piston frequency even when the piston speed is the same.

[0130] During the extension stroke, the oil L is introduced from the cylinder chamber 19 into the first chamber 181 of the frequency sensitive mechanism 130 through the passage holes 37 of the first passage 43, the passages in the passage groove 38, the passages in the notch 81, the passages in the groove portion 30, and the passage groove 158. Then, the valve member 133 abutting against the flexible member 135, the seat portion 154, and the support member 143 has its valve disc 171 bend the flexible member 135 abutting at the first support portion 178 in a direction away from the bottom portion 150 in the axial direction of the case member 131. At the same time, the valve disc 171 compresses and deforms the biasing portion 174 abutting against the support member 143 in the axial direction of the case member 131 between the support member 143. At the same time, the valve disc 171 bends in a tapered shape with the contact point with the flexible member 135 as a fulcrum so that the second support portion 179 is farther away from the bottom portion 150 in the axial direction of the case member 131 than the first support portion 178 .

[0131] When the introduction of oil liquid L into first chamber 181 progresses further and flexible member 135 abuts against stopper 142 to restrict bending, valve disc 171 bends in a tapered manner, with the contact point with flexible member 135 as a fulcrum, so that second support portion 179 is further away from bottom 150 in the axial direction of case member 131 than first support portion 178, while further compressing and deforming biasing portion 174 in the axial direction of case member 131 between support member 143. The valve member 133 expands the volume of the first chamber 181 in the above manner, and introduces the oil L into the first chamber 181. At that time, the valve member 133 discharges the oil L from the second chamber 182 to the cylinder chamber 20 through the passage portion 185.

[0132] Here, in the extension stroke when the piston frequency is high, the stroke of the piston 18 is small. Therefore, the amount of oil L introduced from the cylinder chamber 19 to the first chamber 181 through the passages in the multiple passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81, the passage in the groove portion 30, and the passage in the passage groove 158 is small. Therefore, although the valve member 133 deforms as described above, it does not deform to near its limit.

[0133] Therefore, during the extension stroke when the piston frequency is high, the valve member 133 of the frequency sensitive mechanism 130 moves and bends as described above while bending the bending member 135 at each extension stroke, thereby introducing the oil L from the cylinder chamber 19 into the first chamber 181. Then, the flow rate of the oil L flowing from the cylinder chamber 19 through the passages in the multiple passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81, the passage in the groove portion 30, the passage in the passage groove 79, and the back pressure chamber 100 to the cylinder chamber 20 while opening the disc valve 99 of the second damping force generating mechanism 110 is reduced. In addition to this, the flow rate of the oil L flowing from the first passage 43 to the cylinder chamber 20 is also reduced while opening the damping valve 91 of the first damping force generating mechanism 41. In addition, by introducing oil L from the cylinder chamber 19 into the first chamber 181, the pressure rise in the back pressure chamber 100 is suppressed compared to when the first chamber 181 is not present, and the damping valve 91 of the first damping force generating mechanism 41 is more likely to open. As a result, the damping force on the extension side becomes softer.

[0134] On the other hand, in the extension stroke when the piston frequency is low, the stroke of the piston 18 is large. Therefore, a large amount of oil L is introduced from the cylinder chamber 19 to the first chamber 181 through the passage holes 37 of the first passage 43, the passages in the passage groove 38, the passages in the notch 81, the passages in the groove portion 30, and the passage groove 158. Therefore, although the oil L flows from the cylinder chamber 19 to the first chamber 181 at the beginning of the stroke of the piston 18, the flexible member 135 and the valve member 133 are deformed to near their limits and do not deform any further thereafter. As a result, the oil L does not flow from the cylinder chamber 19 to the first chamber 181. As a result, the flow rate of the oil L flowing from the cylinder chamber 19 through the passages in the passage holes 37 and the passage groove 38 of the first passage 43, the passage in the notch 81, the passage in the groove portion 30, the passage in the passage groove 79, and the back pressure chamber 100 to the cylinder chamber 20 while opening the second damping force generating mechanism 110 is not reduced. In addition to this, the flow rate of the oil L flowing from the first passage 43 to the cylinder chamber 20 while opening the damping valve 91 of the first damping force generating mechanism 41 is also not reduced. In addition, since the oil L is not introduced from the cylinder chamber 19 to the first chamber 181, the pressure in the back pressure chamber 100 increases, and the damping valve 91 of the first damping force generating mechanism 41 is less likely to open. As a result, the damping force becomes harder during the extension stroke when the piston frequency is low than when the piston frequency is high.

[0135] During the compression stroke, the pressure in the cylinder chamber 20 increases, but the valve disc 171 of the valve member 133 of the frequency sensitive mechanism 130 abuts against the seat portion 154 of the case member 131 at the second support portion 179 to suppress the expansion of the second chamber 182. Therefore, the amount of oil L introduced from the cylinder chamber 20 to the second chamber 182 through the passage portion 185 is suppressed. As a result, the flow rate of the oil L introduced from the cylinder chamber 20 to the first passage 44, passing through the first damping force generating mechanism 42 and flowing into the cylinder chamber 19 does not decrease. Therefore, the damping force becomes hard. During the compression stroke, when the piston speed increases and the pressure in the second chamber 182 becomes higher than the pressure in the first chamber 181 by a predetermined value or more, the first support portion 178 on the inner periphery side of the valve member 133 moves away from the flexible member 135. In other words, the check valve 193 opens. As a result, the oil L flows from the cylinder chamber 20 to the cylinder chamber 19 via the passage portion 185, the second chamber 182, the check valve 193, the first chamber 181, the passage in the passage groove 158, the passage in the groove portion 30, the passage in the notch 81, the passage groove 38 of the first passage 43, and the passages in the multiple passage holes 37. In this way, the check valve 193 opens, and the valve member 133 suppresses the pressure difference between the second chamber 182 side and the first chamber 181 side. Therefore, the valve member 133 is prevented from bending excessively.

[0136] The above-mentioned Patent Document 1 describes a shock absorber having a pressure-controlled valve that applies back pressure to the valve in the closing direction. Some shock absorbers of this type use a damping valve to soften the damping force when high-frequency vibration is input and the piston speed is fast, and harden the damping force when low-frequency vibration is input and the piston speed is slow. In this case, the damping valve is often set to a low rigidity because the closing pressure is low when the damping force is softened and the valve opening amount is determined by the rigidity (ease of bending). In addition, when the damping force is hardened, back pressure is applied to the damping valve so that the closing pressure is high, and the valve opening amount is suppressed. In this case, the valve is deformed due to the pressure difference between the opening pressure and the closing pressure, and the stress near the fulcrum at that time increases, which may affect durability. Increasing the rigidity of the valve improves durability, but increases the lower limit of the damping force when the damping force is softened.

[0137] The shock absorber 1 of the first embodiment includes a first damping force generating mechanism 41, a pilot valve 60 fixed at the radially inner side from both axial sides and arranged to be able to close the first passage 43, and one or more valve discs 53 fixed at the radially inner fixed part 201 from both axial ends together with the pilot valve 60, generating a biasing force in a direction to close the first passage 43. The valve disc 53 has a first hole 205 and a second hole 206 formed in a part radially outer than the fixed part 201, which promote axial bending at the radially outer side more than the radially inner side. The valve disc 53 ensures the rigidity of the inner region part 207 near the fixed part 201, while the first hole 205 and the second hole 206 gradually reduce the rigidity from the inner diameter side to the outer diameter side. Therefore, the valve disc 53 ensures the rigidity near the fixed part 201, so that the amount of bending near the fixed part 201 is reduced and the stress near the fixed part 201 is reduced. Therefore, the durability of the valve disc 53 can be improved. In addition, the rigidity of the valve disc 53 is gradually reduced from the radially inner portion to the radially outer portion by the first hole 205 and the second hole 206, making the radially outer portion more flexible. Therefore, the influence on the lower limit value of the damping force when the characteristic is soft can be suppressed.

[0138] Furthermore, in the shock absorber 1 of the first embodiment, the pilot valve 60 is formed with a larger diameter than the valve disc 53, and is deflected by the pressure applied from the second passage 102 so that the radially outer side of the valve seat portion 48 covers the valve disc 53. As a result, the pressure applied from the second passage 102 acts on the valve disc 53 in the valve closing direction via the pilot valve 60. In this way, improved durability and ease of deflection can be obtained even in the valve disc 53 in the valve closing direction when the pressure of the second passage 102 is applied.

[0139] Furthermore, in the shock absorber 1 of the first embodiment, the valve disc 53 has the first hole 205 provided radially inward and the second hole 206 provided radially outward from the first hole 205, which promotes axial deflection more on the radially outer side than on the radially inner side. Therefore, the portion of the valve disc 53 that promotes axial deflection more on the radially outer side than on the radially inner side can be easily formed by press molding or the like.

[0140] Furthermore, in the shock absorber 1 of the first embodiment, the second hole 206 is formed to have a larger diameter than the first hole 205, so that it is easier to promote axial bending on the radial outer side more than on the radial inner side.

[0141] Furthermore, in the shock absorber 1 of the first embodiment, the outer peripheral end surface 203 on the radially outer side of the valve disc 53 is formed of an annular plate-shaped member, so that distortion and the like is unlikely to occur during processing.

[0142] Furthermore, in the shock absorber 1 of the first embodiment, the valve disc 53 is provided at a second axial end of the pilot valve 60 having a seal member 86 at a first axial end. Therefore, the opposite side of the pilot valve 60 from the valve disc 53 can be used as a back pressure chamber 100. The pressure of this back pressure chamber 100 can be applied to the valve disc 53 via the pilot valve 60.

[0143] In the shock absorber 1 of the first embodiment, all the valve discs 53 have the first hole 205 and the second hole 206 that promote axial bending on the radial outer side more than on the radial inner side. However, any one of the valve discs 53 may not have the first hole 205 and the second hole 206. That is, it is sufficient that at least one of the valve discs 53 has the first hole 205 and the second hole 206. In that case, the other valve discs 53 may have a shape that does not have a portion that penetrates in the axial direction between the outer peripheral end face 203 and the inner peripheral end face 202. In that case, any valve disc 53 that is located at any position in the stacking direction among all the valve discs 53 may have the first hole 205 and the second hole 206.

[0144] [Second embodiment] Next, the second embodiment will be described with a focus on the differences from the first embodiment, mainly based on Fig. 6. Note that the same names and symbols are used for the parts common to the first embodiment. In the second embodiment, a valve disc 53A shown in Fig. 6, which is partially different from the valve disc 53 in the shock absorber 1 of the first embodiment, is provided instead of the valve disc 53. In the second embodiment, all of the valve discs 53 are replaced with the same number of valve discs 53A.

[0145] Each valve disc 53A has an inner peripheral end surface 202 and an outer peripheral end surface 203 similar to those of the valve disc 53. The valve disc 53A has a plurality of, specifically five, irregularly shaped holes 241A (flexure promoting portions) instead of the first hole 205 and the second hole 206. All of the irregularly shaped holes 241A penetrate the valve disc 53A in the axial direction, i.e., in the thickness direction. These irregularly shaped holes 241A all have the same shape when the valve disc 53A is viewed in the axial direction.

[0146] All of the irregular holes 241A are disposed at equal intervals in the circumferential direction of the inner circumferential end face 202 and the outer circumferential end face 203, i.e., in the circumferential direction of the valve disc 53A. All of the irregular holes 241A are disposed at positions equidistant from the center of the inner circumferential end face 202, i.e., the center of the valve disc 53A.

[0147] The irregular hole 241A has an arc-shaped portion 242A and a pair of linear portions 243A. The arc-shaped portion 242A is coaxial with the outer peripheral end face 203 and has an arc shape with a smaller diameter than the outer peripheral end face 203. The pair of linear portions 243A are both linear and have the same length. The pair of linear portions 243A extend from both ends of the arc-shaped portion 242A toward the inner peripheral end face 202 and merge with each other. Thus, the irregular hole 241A is fan-shaped. The irregular hole 241A is formed so as to expand in diameter toward the outside in the radial direction of the valve disc 53A. The pair of linear portions 243A form an obtuse angle.

[0148] All of the irregular holes 241A are disposed in a range outside the fixed portion 201 in the radial direction of the valve disc 53A, in other words, in a range between the fixed portion 201 and the outer circumferential edge portion 204 in the radial direction. In other words, the valve disc 53A has a plurality of irregular holes 241A formed in a part that is radially outside the fixed portion 201 and radially inside the outer circumferential edge portion 204.

[0149] The circumferential length of the irregular holes 241A increases toward the outside in the radial direction of the valve disc 53A. In the valve disc 53A, an annular region around the fixed part 201 where the irregular holes 241A are not formed is the inner region 207A. The inner region 207A is located outside the fixed part 201 in the radial direction of the valve disc 53. In the valve disc 53A, an annular region where the multiple irregular holes 241A are formed is the rigidity change part 245A. The rigidity of the rigidity change part 245A decreases toward the outside in the radial direction of the valve disc 53A. The rigidity change part 245A is located outside the inner region 207A and inside the outer circumferential edge part 204 in the radial direction of the valve disc 53.

[0150] The valve disc 53A has a plurality of irregular holes 241A which promote axial bending at the radially outer side more than at the radially inner side. The valve disc 53A has the irregular holes 241A at a part radially outer side than the fixed portion 201 and at a part radially inner side than the outer circumferential edge portion 204.

[0151] The valve disc 53A has a constant outer diameter over its entire circumference, and a constant inner diameter over its entire circumference. The valve disc 53A has a constant radial width. The valve disc 53A has an outer diameter equal to the outer diameter of the valve disc 53, and an inner diameter equal to the inner diameter of the valve disc 53.

[0152] The valve discs 53A, with multiple valve discs of the same shape stacked, undergo slight elastic deformation to come into contact with the valve disc 52 (see FIG. 3). As a result, each of the multiple valve discs 53A generates a biasing force in a direction to come into contact with the valve seat portion 48 (see FIG. 3) due to its own elasticity. As a result, the multiple valve discs 53A apply a biasing force to the valve disc 52 (see FIG. 3) in a direction to come into contact with the valve seat portion 48 (see FIG. 3) due to its own elasticity. There does not have to be multiple valve discs 53A, and only one valve disc 53A may be used.

[0153] In the second embodiment, the valve disc 53A has an irregular hole 241A formed in a part radially outward of the fixed part 201, which promotes axial bending of the stiffness change part 245A radially outward of the inner region 207A on the radially inner side. The irregular hole 241A promotes axial bending of the stiffness change part 245A radially outward more than the radially inward. The irregular hole 241A of the valve disc 53A ensures the stiffness of the inner region 207A near the fixed part 201, while gradually reducing the stiffness from the inner diameter side to the outer diameter side in the part outer diameter side of the inner region 207A. Therefore, like the valve disc 53, the durability of the valve disc 53A can be improved, and the effect on the lower limit value of the damping force when the characteristic is soft can be suppressed.

[0154] In addition, the valve disc 53A has a special shaped hole 241A that promotes axial bending on the radial outside more than on the radial inside, and is formed so as to have a larger diameter toward the radial outside. This makes it easier to promote axial bending on the radial outside more than on the radial inside.

[0155] Furthermore, since the outer peripheral end surface 203 of the valve disc 53A on the radially outer side is formed from an annular plate-like member, distortion and the like is unlikely to occur during processing.

[0156] Here, it is not necessary that any one of all the valve discs 53A has the irregular hole 241A. In other words, it is sufficient that at least one of the valve discs 53A has the irregular hole 241A. In that case, the other valve discs 53A may have a shape that does not have a portion that penetrates in the axial direction between the outer circumferential end face 203 and the inner circumferential end face 202. Furthermore, in that case, among all the valve discs 53A, any valve disc 53A located at any position in the stacking direction may have the irregular hole 241A.

[0157] [Third embodiment] Next, the third embodiment will be described with a focus on the differences from the first embodiment, mainly with reference to Fig. 7. The same parts as those in the first embodiment will be designated by the same names and reference numerals. In the third embodiment, a valve disc 53B shown in Fig. 7 which is partially different from the valve disc 53 in the shock absorber 1 of the first embodiment is provided instead of the valve disc 53. In the third embodiment, all of the valve discs 53 are replaced with the same number of valve discs 53B.

[0158] The valve disc 53B has an inner peripheral end surface 202 similar to that of the valve disc 53, and an outer peripheral end surface 203B different from that of the valve disc 53. The valve disc 53B has a plurality of, specifically eight, first grooves 205B (flexure promoting portions) and a plurality of, specifically eight, second grooves 206B (flexure promoting portions) instead of the first holes 205 and the second holes 206. All of the first grooves 205B and all of the second grooves 206B penetrate the valve disc 53B in the axial direction, i.e., the thickness direction. All of the first grooves 205B and all of the second grooves 206B extend in the radial direction of the valve disc 53B.

[0159] All the first grooves 205B are linear grooves of the same shape extending from the outer peripheral end face 203B in the radial direction of the valve disc 53B. All the second grooves 206B are linear grooves of the same shape extending from the outer peripheral end face 203B in the radial direction of the valve disc 53B. The outer peripheral end face 203B has a cylindrical surface shape that is interrupted in the circumferential direction by forming a plurality of first grooves 205B and a plurality of second grooves 206B. The outer diameter of the portion of the outer peripheral end face 203B excluding the first grooves 205B and the second grooves 206B is equal to the outer diameter of the outer peripheral end face 203 of the valve disc 53. The length of the second grooves 206B in the radial direction of the valve disc 53B is shorter than the length of the first grooves 205B in the same direction. In other words, the first grooves 205B extend further inward in the radial direction of the valve disc 53B than the second grooves 206B.

[0160] All of the first grooves 205B are disposed at equal intervals in the circumferential direction of the inner circumferential end face 202, i.e., in the circumferential direction of the valve disc 53B. All of the first grooves 205B are disposed such that their inner ends in the radial direction of the inner circumferential end face 202, i.e., in the radial direction of the valve disc 53B, are equidistant from the center of the inner circumferential end face 202, i.e., the center of the valve disc 53B. All of the second grooves 206B are disposed at equal intervals in the circumferential direction of the valve disc 53. All of the second grooves 206B are disposed such that the inner ends in the radial direction of the valve disc 53B are equidistant from the center of the valve disc 53B.

[0161] In the valve disc 53B, one second groove 206B is disposed in the center between adjacent first grooves 205B in the circumferential direction of the valve disc 53B. In other words, in the valve disc 53B, the first grooves 205B and the second grooves 206B are alternately disposed at equal intervals in the circumferential direction.

[0162] All of the first grooves 205B and all of the second grooves 206B are arranged in a range radially outward of the fixed portion 201 of the valve disc 53B. In other words, the valve disc 53B has a plurality of first grooves 205B and a plurality of second grooves 206B formed in a portion radially outward of the fixed portion 201.

[0163] In the valve disc 53, an annular region near the fixed part 201 where neither the first groove 205B nor the second groove 206B is formed is the inner region 207B. The inner region 207B is located outside the fixed part 201 in the radial direction of the valve disc 53B. In addition, in the valve disc 53, an annular region where only the multiple first grooves 205B are formed is the intermediate region 208B. The intermediate region 208B is located outside the inner region 207B in the radial direction of the valve disc 53B. In addition, in the valve disc 53B, an annular region where both the multiple first grooves 205B and the multiple second grooves 206B are formed is the outer region 209B. The outer region 209B is located outside the intermediate region 208B in the radial direction of the valve disc 53.

[0164] In the valve disc 53B, the intermediate region 208B in which the multiple first grooves 205B are formed has a lower axial rigidity than the inner region 207B in which neither the first groove 205B nor the second groove 206B is formed. In addition, in the valve disc 53B, the outer region 209B in which the multiple second grooves 206B are formed in addition to the multiple first grooves 205B has a lower axial rigidity than the intermediate region 208B in which only the multiple first grooves 205B are formed. In the valve disc 53B, the multiple first grooves 205B and the multiple second grooves 206B promote axial bending in the intermediate region 208B more than the inner region 207B on the radial inside, and promote axial bending in the outer region 209B on the radial outside more than the intermediate region 208B on the radial inside. In the valve disc 53B, the first groove 205B and the second groove 206B are provided in a part radially outside of the fixed part 201.

[0165] The valve discs 53B, with multiple valve discs of the same shape stacked, undergo slight elastic deformation to come into contact with the valve disc 52 (see FIG. 3). As a result, each of the multiple valve discs 53B generates a biasing force in a direction to abut against the valve seat portion 48 (see FIG. 3) due to its own elasticity. As a result, the multiple valve discs 53B apply a biasing force to the valve disc 52 (see FIG. 3) in a direction to abut against the valve seat portion 48 (see FIG. 3) due to its own elasticity. There does not need to be multiple valve discs 53B, and only one valve disc 53B may be used.

[0166] In the third embodiment, the valve disc 53B is formed with a first groove 205B and a second groove 206B that promote axial bending at the radially outer side more than the radially inner side in a part radially outer than the fixed part 201. The valve disc 53B ensures the rigidity of the inner region 207B near the fixed part 201, while the first groove 205B reduces the rigidity of the intermediate region 208B on the outer diameter side more than the inner region 207B on the inner diameter side. Also, the valve disc 53B has the first groove 205B and the second groove 206B that reduce the rigidity of the outer region 209B on the outer diameter side more than the rigidity of the intermediate region 208B on the inner diameter side. Therefore, similar to the valve disc 53, the durability of the valve disc 53B can be improved, and the influence on the lower limit value of the damping force when the characteristics are soft can be suppressed.

[0167] Furthermore, since the first groove 205B and the second groove 206B both extend radially inward from the outer peripheral end face 203B of the valve disc 53B, it is easier to promote axial deflection on the radially outer side than on the radially inner side.

[0168] Here, any one of all the valve discs 53B may not have the first groove 205B and the second groove 206B. That is, it is sufficient that at least one of the valve discs 53B has the first groove 205B and the second groove 206B. In this case, the other valve discs 53B may be shaped so that there is no portion that penetrates in the axial direction between the outer peripheral end face 203B and the inner peripheral end face 202. In this case, any valve disc 53B located at any position in the stacking direction among all the valve discs 53B may have the first groove 205B and the second groove 206B.

[0169] It is also possible to selectively combine the valve discs 53, 53A, and 53B as appropriate. That is, it is possible to combine all of the valve discs 53, 53A, and 53B with the damping valve 91. Also, it is possible to combine only the valve discs 53 and 53A of the valve discs 53, 53A, and 53B with the damping valve 91. Also, it is possible to combine only the valve discs 53 and 53B of the valve discs 53, 53A, and 53B with the damping valve 91. Also, it is possible to combine only the valve discs 53A ...

[0170] Although the hydraulic shock absorber has been described as an example in the first to third embodiments, the above structure can also be applied to a shock absorber that uses water or air as the working fluid. [Industrial Applicability]

[0171] According to the above aspects of the present invention, the durability of the valve can be improved, and thus the industrial applicability is great. [Explanation of symbols]

[0172] 1...shock absorber, 2...cylinder, 18...piston, 19...cylinder chamber, 20...cylinder chamber, 21...piston rod, 41...first damping force generating mechanism, 43...first passage, 48...valve seat portion (seat portion), 53, 53A, 53B...valve disc (second valve), 60...pilot valve (first valve), 86...sealing member, 102...second passage, 110...second damping force generating mechanism, 201...fixed portion, 203...outer peripheral end surface (radially outer end surface), 205...first hole (deflection promoting portion), 206...second hole (deflection promoting portion), 241A...irregularly shaped hole (deflection promoting portion), 205B...first groove (deflection promoting portion), 206B...second groove (deflection promoting portion).

Claims

1. A cylinder in which a working fluid is sealed; a piston slidably fitted in the cylinder and dividing the interior of the cylinder into two cylinder chambers; a piston rod having a first end connected to the piston and a second end extending outside the cylinder; a first passage through which the working fluid flows out from at least one of the cylinder chambers as the piston moves; a first damping force generating mechanism provided in the first passage and configured to generate a damping force; a second passage provided in parallel with the first passage, through which the working fluid flows out of at least one of the cylinder chambers as the piston moves and which pressurizes the first damping force generating mechanism in a valve closing direction; a second damping force generating mechanism provided in the second passage; having the first damping force generating mechanism comprises: a valve disc whose radially inner side is fixed from both axial sides and which is arranged to be able to close the first passage; a first valve whose radially inner fixed part is fixed together with the valve disc from both axial ends; and one or more second valves whose radially inner fixed parts are fixed together with the valve disc from both axial ends and which generate a biasing force against the valve disc in a direction to close the first passage, the second valve is formed to have a diameter larger than an inner diameter of a seat portion provided on an outer circumferential side of the first passage, and at least one of the second valves is formed with a deflection promoting portion that promotes axial deflection at a radially outer side relative to the radially inner side in a part of the second valve that is radially outer than the fixed portion, The deflection promotion portion includes a first hole provided radially inward and a second hole provided radially outward from the first hole, The second hole is formed to have a larger diameter than the first hole.

2. A cylinder in which a working fluid is sealed; a piston slidably fitted in the cylinder and dividing the interior of the cylinder into two cylinder chambers; a piston rod having a first end connected to the piston and a second end extending outside the cylinder; a first passage through which the working fluid flows out from at least one of the cylinder chambers as the piston moves; a first damping force generating mechanism provided in the first passage and configured to generate a damping force; a second passage provided in parallel with the first passage, through which the working fluid flows out of at least one of the cylinder chambers as the piston moves and which pressurizes the first damping force generating mechanism in a valve closing direction; a second damping force generating mechanism provided in the second passage; having the first damping force generating mechanism comprises: a valve disc whose radially inner side is fixed from both axial sides and which is arranged to be able to close the first passage; a first valve whose radially inner fixed part is fixed together with the valve disc from both axial ends; and one or more second valves whose radially inner fixed parts are fixed together with the valve disc from both axial ends and which generate a biasing force against the valve disc in a direction to close the first passage, the second valve is formed to have a diameter larger than an inner diameter of a seat portion provided on an outer circumferential side of the first passage, and at least one of the second valves is formed with a deflection promoting portion that promotes axial deflection at a radially outer side relative to the radially inner side in a part of the second valve that is radially outer than the fixed portion, The deflection promoting portion is formed so as to expand in diameter radially outward.

3. 3. The shock absorber according to claim 1, wherein the second valve is formed of a plate-like member having an annular radial outer end surface.

4. the first valve having a seal member at a first axial end; The shock absorber according to claim 1 or 2, wherein the second valve is provided at a second axial end of the first valve.

5. 3. The shock absorber according to claim 1, wherein the first valve is formed to have a larger diameter than the second valve, and the first valve is deflected radially outwardly of the seat portion so as to cover the second valve due to pressure applied from the second passage.

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