Buffer

Abstract

This shock absorber comprises a cylinder, a piston, a piston rod, a first passage, a second passage, a first damping force mechanism, and a second damping force mechanism. The second damping force mechanism has: a partition member that is provided in the second passage to define the second passage, is displaced by working fluid flowing in due to movement of the piston, and discharges at least part of the working fluid in the second passage into the cylinder; and a valve closing part that forms a closed pressure chamber between the inside of the second passage and the partition member, and restricts the movement of the working fluid in the pressure chamber, and varies damping force.

Description

Technical Field

[0001] The present invention relates to a shock absorber. This application claims priority based on Japanese Patent Application No. 2022-087331 filed in Japan on May 30, 2022, and incorporates its content herein by reference.

Background Art

[0002] There is a shock absorber having a partitioning member that partitions a passage and whose damping force characteristics are variable according to the vibration state (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, it is desired to improve the durability of the partitioning member in the shock absorber.

[0005] Therefore, an object of the present invention is to provide a shock absorber capable of improving the durability of the partitioning member.

Means for Solving the Problems

[0006] To achieve the above object, a shock absorber according to one aspect of the present invention includes a cylinder filled with a working fluid, a piston slidably fitted in the cylinder and partitioning the inside of the cylinder into two chambers, a piston rod connected to the piston and extending outside the cylinder, a first passage through which the working fluid can flow between the two chambers by the movement of the piston, a second passage formed in parallel with the first passage and provided so that at least one of the working fluids in the two chambers can flow in by the movement of the piston, a first damping force mechanism provided in the first passage for generating a damping force, a partitioning member provided in the second passage for partitioning the second passage and displaced by the working fluid flowing in by the movement of the piston to discharge at least a part of the working fluid in the second passage into the cylinder, a closing valve portion for forming a pressure chamber closed between the inside of the second passage and the partitioning member and restricting the movement of the working fluid in the pressure chamber, and a second damping force mechanism for making the damping force variable.

Advantages of the Invention

[0007] According to the shock absorber according to the above aspect of the present invention, the durability of the partitioning member can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

[0009] [First Embodiment] The shock absorber 1 according to the first embodiment will be described below with reference to FIGS. 1 to 4. In the following description, for convenience of explanation, the upper side in FIGS. 1 to 12 is referred to as "upper", and the lower side in FIGS. 1 to 12 is referred to as "lower".

[0010] As shown in FIG. 1, the shock absorber 1 according to the first embodiment is a double-tube type hydraulic shock absorber. The shock absorber 1 is used for a vehicle suspension device, specifically an automobile. The shock absorber 1 includes a cylinder 2. The cylinder 2 is filled with an oil liquid L 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 a bottomed cylinder. 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 coincides with the central axis of the outer cylinder 4. The space between the inner cylinder 3 and the outer cylinder 4 forms a reservoir chamber 6.

[0011] The outer cylinder 4 has a barrel portion 11 and a bottom portion 12. The barrel portion 11 and the bottom portion 12 are integrally formed. The barrel portion 11 is cylindrical. The bottom portion 12 closes the lower part of the barrel portion 11. An attachment eye (not shown in detail) is fixed to the bottom portion 12 on the outer side opposite to the barrel portion 11 in its axial direction.

[0012] The shock absorber 1 includes a piston 18. The piston 18 is inserted into the inner cylinder 3 of the cylinder 2. The piston 18 is slidably fitted into the inner cylinder 3 of the cylinder 2. The piston 18 divides the inside of the inner cylinder 3 of the cylinder 2 into two chambers, an upper chamber 19 on one side and a lower chamber 20 on the other side. In the axial direction of the cylinder 2, the upper chamber 19 is on the side opposite to the bottom portion 12 with respect to the piston 18. In the axial direction of the cylinder 2, the lower chamber 20 is on the side of the bottom portion 12 with respect to the piston 18. Oil L as a working fluid is enclosed in the upper chamber 19 and the lower chamber 20 inside the inner cylinder 3. Oil L as a working fluid and gas G are enclosed in the reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4.

[0013] The shock absorber 1 includes a piston rod 21. One end side, the first end portion, of the piston rod 21 in its axial direction is disposed inside the inner cylinder 3 of the cylinder 2. The piston rod 21 is connected to the piston 18 at this first end portion. The second end portion of the piston rod 21 in its axial direction, which is opposite to this first end portion, extends from the cylinder 2 to the outside of the cylinder 2. The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 and the piston rod 21 move integrally. The stroke in which the shock absorber 1 moves in the direction of increasing the protruding amount of the piston rod 21 from the cylinder 2 is the extension stroke in which the overall length extends. The stroke in which the shock absorber 1 moves in the direction of reducing the protruding amount of the piston rod 21 from the cylinder 2 is the compression stroke in which the overall length contracts. The piston 18 of the shock absorber 1 moves toward the upper chamber 19 side during the extension stroke. The piston 18 of the shock absorber 1 moves toward the lower chamber 20 side during the compression stroke.

[0014] 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 inside the radial direction of each of the rod guide 22 and the seal member 23 and slides along their axial directions. The piston rod 21 extends from inside the cylinder 2 to the outside of the cylinder 2 beyond the seal member 23.

[0015] The rod guide 22 restricts the piston rod 21 from moving radially with respect to the inner cylinder 3 and the outer cylinder 4 of the cylinder 2. The piston rod 21 is fitted to the rod guide 22 and the piston 18 is fitted inside the inner cylinder 3. Thereby, the central axis of the piston rod 21 coincides with the central axis of the cylinder 2. The rod guide 22 supports the piston rod 21 so as to be movable in the axial direction of the piston rod 21. The outer peripheral portion of the seal member 23 is in close contact with the body portion 11 of the outer cylinder 4. The inner peripheral portion of the seal member 23 is in close contact with the outer peripheral portion of the piston rod 21. The piston rod 21 moves in the axial direction of the seal member 23 with respect to the seal member 23. The seal member 23 suppresses the leakage of the oil liquid L inside the inner cylinder 3, the high-pressure gas G and the oil liquid L inside the reservoir chamber 6 to the outside.

[0016] The outer peripheral portion of the rod guide 22 has a larger diameter at the upper part than at the lower part. The rod guide 22 is fitted to the inner peripheral portion of the upper end of the inner cylinder 3 at the lower part with a smaller diameter. The rod guide 22 is fitted to the inner peripheral portion of the upper part of the body portion 11 of the outer cylinder 4 at the upper part with a larger diameter. A base valve 25 is installed on the bottom 12 of the outer cylinder 4. The base valve 25 is positioned radially with respect to the outer cylinder 4. The inner peripheral portion of the lower end of the inner cylinder 3 is fitted to the base valve 25.

[0017] The upper end portion of the outer cylinder 4 is caulked 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 caulked portion and the rod guide 22.

[0018] The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28. Both the main shaft portion 27 and the mounting shaft portion 28 are rod-shaped.

[0019] The outer diameter of the mounting shaft portion 28 is smaller than the outer diameter of the main shaft portion 27. The mounting shaft portion 28 is disposed within the cylinder 2. A 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 portion of the main shaft portion 27 on the mounting shaft portion 28 side in the axial direction of the main shaft portion 27. The shaft step portion 29 extends in a direction perpendicular to the central axis of the piston rod 21.

[0020] A groove portion 30 is formed on the outer peripheral portion of the mounting shaft portion 28 of the piston rod 21. The groove portion 30 extends in the axial direction of the mounting shaft portion 28. The groove portion 30 is formed by notching the outer peripheral portion of the mounting shaft portion 28 in a planar shape parallel to the central axis of the mounting shaft portion 28. Two groove portions 30 are formed at intervals in the circumferential direction of the mounting shaft portion 28. A threaded portion 31 is formed on the outer peripheral portion of the end portion of the mounting shaft portion 28 on the side opposite to the main shaft portion 27 with respect to the groove portion 30 in the axial direction of the mounting shaft portion 28.

[0021] For example, the portion of the piston rod 21 protruding from the cylinder 2 of the shock absorber 1 is disposed at the upper part and connected to the vehicle body. At this time, the shock absorber 1 has a mounting eye (not shown in detail) provided on the cylinder 2 side disposed at the lower part and connected to the vehicle wheel side. Conversely, the shock absorber 1 may be configured such that the cylinder 2 side is connected to the vehicle body. In this case, the piston rod 21 of the shock absorber 1 is connected to the vehicle wheel side.

[0022] As shown in FIG. 2, the piston 18 has a piston body 35 and a sliding member 36. The piston body 35 is configured by combining a divided body 33 and a divided body 34. Both the divided bodies 33 and 34 are made of metal and are both annular. The inner diameter of the divided body 33 is smaller than the inner diameter of the divided body 34. The sliding member 36 is made of synthetic resin and is in the shape of an annular band. The sliding member 36 is integrally attached to the outer peripheral surface of the piston body 35 in a state where the divided body 33 and the divided body 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 piston 18 is fitted to the mounting shaft portion 28 of the piston rod 21. The piston 18 slides axially with respect to the inner cylinder 3 with the sliding member 36 in contact with the inner cylinder 3.

[0023] The piston body 35 is provided with a passage hole 37, a passage groove 38, a passage hole 39, and a passage groove 40.

[0024] The passage hole 37 extends in the axial direction of the piston body 35. A plurality of passage holes 37 (only one is shown in FIG. 2 in terms of cross-section) are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35.

[0025] The passage hole 39 extends in the axial direction of the piston body 35. A plurality of passage holes 39 (only one is shown in FIG. 2 in terms of cross-section) are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35. In the piston body 35, the passage hole 37 and the passage hole 39 are formed alternately at equal pitches one by one in the circumferential direction of the piston body 35.

[0026] The passage groove 38 is formed in an annular shape in the circumferential direction of the divided body 34 of the piston body 35. The passage groove 38 is formed at the end portion of the divided body 34 on the side opposite to the divided body 33 in the axial direction. All the passage holes 37 open into the passage groove 38 on this end portion side in the axial direction of the piston body 35.

[0027] The passage groove 40 is formed in the split body 33 of the piston body 35 in an annular shape in the circumferential direction of the split body 33. The passage groove 40 is formed at an end portion of the split body 33 on the side opposite to the split body 34 in the axial direction of the split body 33. At the end portion of all the passage holes 39 on the side opposite to the passage groove 38 in the axial direction of the piston body 35, they open into the passage groove 40.

[0028] Inside the piston 18, the inside of the plurality of passage holes 37 and the inside of the passage groove 38 form the first passage 43. The first passage 43 penetrates the piston 18 in the axial direction of the piston 18. Therefore, the first passage 43 enables the hydraulic fluid L, which is the working fluid, to flow and communicate between the upper chamber 19 and the lower chamber 20 due to the movement of the piston 18.

[0029] Inside the piston 18, the inside of the plurality of passage holes 39 and the inside of the passage groove 40 form the first passage 44. The first passage 44 penetrates the piston 18 in the axial direction of the piston 18. Therefore, the first passage 44 enables the hydraulic fluid L, which is the working fluid, to flow and communicate between the upper chamber 19 and the lower chamber 20 due to the movement of the piston 18.

[0030] Both the first passage 43 and the first passage 44 are provided in the piston 18.

[0031] A damping force mechanism 41 (first damping force mechanism) is provided in the first passage 43. The damping force mechanism 41 opens and closes the first passage 43 to generate a damping force. The damping force mechanism 41 is arranged on the lower chamber 20 side, which is one end side in the axial direction of the piston 18, and is attached to the piston rod 21. Therefore, the first passage 43 serves as a passage for the hydraulic fluid L as the working fluid to move from the upper chamber 19 to the lower chamber 20 when the piston 18 moves toward the upper chamber 19 side. That is, the first passage 43 is a passage for the hydraulic fluid L to move from the upper chamber 19, which is the upstream side in the extension stroke, to the lower chamber 20, which is the downstream side. The damping force mechanism 41 is an extension-side damping force generation mechanism that suppresses the flow of the hydraulic fluid L from the first passage 43 to the lower chamber 20 during the extension stroke to generate a damping force.

[0032] The first passage 44 is provided with a damping force mechanism 42 (first damping force mechanism). The damping force mechanism 42 opens and closes the first passage 44 to generate a damping force. The damping force mechanism 42 is disposed on the upper 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. Therefore, the first passage 44 serves as a passage through which the hydraulic fluid L moves from the lower chamber 20 toward the upper chamber 19 when the piston 18 moves to the lower chamber 20 side. That is, the first passage 44 is a passage through which the hydraulic fluid L moves from the lower chamber 20, which becomes the upstream side during the compression stroke, toward the upper chamber 19, which becomes the downstream side. The damping force mechanism 42 serves as a compression-side damping force generation mechanism that suppresses the flow of the hydraulic fluid L from the first passage 44 to the upper chamber 19 during the compression stroke to generate a damping force.

[0033] The piston body 35 has an insertion hole 45 formed therethrough in the axial direction of the piston body 35 at the center in the radial direction thereof. The insertion hole 45 allows the mounting shaft portion 28 of the piston rod 21 to pass therethrough. The insertion hole 45 has a smaller diameter in the portion formed in the upper chamber 19-side partition 33 than in the portion formed in the lower chamber 20-side partition 34 in the axial direction thereof. The piston body 35 fits onto the mounting shaft portion 28 of the piston rod 21 in the partition 33 having such a smaller inner diameter.

[0034] A valve seat portion 48 is formed at the end of the piston body 35 on the lower chamber 20 side in the axial direction. The valve seat portion 48 is annular. The valve seat portion 48 is disposed outside the piston body 35 in the radial direction from the opening on the lower chamber 20 side of the passage groove 38. The valve seat portion 48 forms a part of the damping force mechanism 41.

[0035] A valve seat portion 49 is formed at the end of the piston body 35 on the upper chamber 19 side in the axial direction. The valve seat portion 49 is annular. The valve seat portion 49 is disposed outside the piston body 35 in the radial direction from the opening on the upper chamber 19 side of the passage groove 40. The valve seat portion 49 forms a part of the damping force mechanism 42.

[0036] On the piston body 35, on the side opposite to the passage groove 38 of the valve seat portion 48 in the radial direction of the piston body 35, the openings on the lower chamber 20 side of all the passage holes 39 are arranged. On the piston body 35, on the side opposite to the passage groove 40 of the valve seat portion 49 in the radial direction of the piston body 35, the openings on the upper chamber 19 side of all the passage holes 37 are arranged.

[0037] On the valve seat portion 48 side in the axial direction of the piston 18, in the axial direction of the piston 18, in order from the piston 18 side, a plurality of (specifically, 2) disks 50, a plurality of (specifically, 5) disks 51, one pilot disk 52, one disk 53, one pilot case 55, one disk 56, a plurality of (specifically, 6) disks 57, one disk 58, and one disk 59 are provided.

[0038] The disks 50, 51, 53, 56 to 59 and the pilot case 55 are all made of metal. The disks 50, 51, 53, 56 to 59 are all perforated circular flat plates with a certain thickness. The disks 50, 51, 53, 56 to 59 all have the mounting shaft portion 28 of the piston rod 21 fitted inside. The pilot disk 52 and the pilot case 55 are both annular. The pilot disk 52 and the pilot case 55 both have the mounting shaft portion 28 of the piston rod 21 fitted inside.

[0039] The pilot case 55 is a bottomed cylindrical shape. In the center of the pilot case 55 in the radial direction, a through hole 70 is formed. The through hole 70 penetrates the pilot case 55 in the axial direction. The through hole 70 has a smaller diameter on the piston 18 side in the axial direction than on the side opposite to the piston 18, and the mounting shaft portion 28 of the piston rod 21 is fitted into this smaller diameter portion.

[0040] The pilot case 55 has a bottom portion 71, an inner cylindrical portion 72, an outer cylindrical portion 73, an inner seat portion 74, and a valve seat portion 75.

[0041] The bottom 71 is a perforated disc shape. A passage hole 78 that penetrates the bottom 71 in the axial direction of the bottom 71 is formed on the bottom 71 radially outside the through hole 70.

[0042] The inner cylindrical portion 72 is cylindrical and protrudes from the inner peripheral edge portion of the bottom 71 along the axial direction of the bottom 71 toward the piston 18 side.

[0043] The outer cylindrical portion 73 is cylindrical and protrudes from the outer peripheral edge portion of the bottom 71 along the axial direction of the bottom 71 to the same side as the inner cylindrical portion 72.

[0044] The passage hole 78 is disposed between the inner cylindrical portion 72 and the outer cylindrical portion 73 in the radial direction of the bottom 71.

[0045] The inner sheet portion 74 is annular and slightly protrudes from the inner peripheral edge portion of the bottom 71 to the side opposite to the inner cylindrical portion 72 in the axial direction. A passage groove 79 that penetrates the inner sheet portion 74 in its radial direction is formed in the inner sheet portion 74.

[0046] The valve sheet portion 75 is annular with a larger diameter than the inner sheet portion 74. The valve sheet portion 75 protrudes from the bottom 71 along the axial direction of the bottom 71 to the same side as the inner sheet portion 74 on the outer side in the radial direction of the inner sheet portion 74.

[0047] The passage hole 78 is disposed between the inner sheet portion 74 and the valve sheet portion 75 in the radial direction of the bottom 71. The passage in the passage groove 79 of the inner sheet portion 74 is always in communication with the passage in the groove portion 30 of the piston rod 21 and the passage in the passage hole 78.

[0048] The plurality of discs 50 are such that the disc 50 on the piston 18 side in the axial direction abuts on a portion radially inside the passage groove 38 of the piston 18. A notch 81 is formed in this disc 50. The passage in the notch 81 is a throttle and is always in communication with the first passage 43 of the piston 18 and the passage in the groove portion 30 of the piston rod 21.

[0049] Of the plurality of disks 51, the disk 51 closest to the piston 18 in the axial direction is in contact with the valve seat portion 48 of the piston 18. The plurality of disks 51 open and close the opening of the first passage 43 formed in the piston 18 by moving away from and coming into contact with the valve seat portion 48.

[0050] The pilot disk 52 is composed of a disk 85 and a seal member 86. The disk 85 is made of metal and is a perforated circular flat plate. The mounting shaft portion 28 of the piston rod 21 is fitted inside the disk 85. Of the plurality of disks 51, the disk 51 farthest from the piston 18 in the axial direction is in contact with the disk 85 of the pilot disk 52.

[0051] The seal member 86 is made of rubber and is adhesively bonded by baking to the side of the disk 85 opposite to the piston 18 in the axial direction. The seal member 86 is fixed to the outer peripheral side of the disk 85 and has an annular shape. The seal member 86 is liquid-tightly fitted over the entire circumference to the inner peripheral portion of the outer cylindrical portion 73 of the pilot case 55. The seal member 86 is axially slidable with respect to the inner peripheral portion of the outer cylindrical portion 73. The seal member 86 always seals the gap between the pilot disk 52 and the outer cylindrical portion 73.

[0052] A plurality of disks 51 and a pilot disk 52 constitute a damping valve 91. The damping valve 91 can be seated on and disengaged from the valve seat portion 48 of the piston 18. The damping valve 91 can open the first passage 43 to the lower chamber 20 by disengaging from the valve seat portion 48. Between the damping valve 91 and the valve seat portion 48 of the piston 18, the first passage 43 is formed. When the damping valve 91 disengages from the valve seat portion 48 of the piston 18 and opens, the hydraulic fluid L from the first passage 43 flows through the space between the piston 18 and the outer cylindrical portion 73 of the pilot case 55 into the lower chamber 20. At that time, the damping valve 91 suppresses the flow of the hydraulic fluid L between it and the valve seat portion 48. The damping valve 91 constitutes an extension-side damping force mechanism 41. In the damping valve 91, a fixed orifice 92 that communicates the first passage 43 with the lower chamber 20 even when in contact with the valve seat portion 48 is formed in at least the disk 51 that contacts the valve seat portion 48 among the plurality of disks 51. This fixed orifice 92 forms the first passage 43 and constitutes the damping force mechanism 41.

[0053] The disk 53 is in contact with the disk 85 of the pilot disk 52. The disk 53 is in contact with the inner cylindrical portion 72 of the pilot case 55. The disk 56 is in contact with the inner seat portion 74 of the pilot case 55.

[0054] Among the plurality of disks 57, the disk 57 on the disk 56 side in the axial direction can be seated on the valve seat portion 75. The plurality of disks 57 constitute a disk valve 99. The disk valve 99 can be seated on and disengaged from the valve seat portion 75. The outer diameter of the disk 58 is smaller than the minimum outer diameter of the disk valve 99. The outer diameter of the disk 59 is larger than the outer diameter of the disk 58.

[0055] The bottom 71, the inner cylindrical portion 72, and the outer cylindrical portion 73 of the pilot case 55, between the pilot disk 52 and the disk 53, and between the bottom 71, the inner sheet portion 74, and the valve seat portion 75 of the pilot case 55, and the disk 56 and the disk valve 99, and the inside of the passage hole 78 of the pilot case 55 form the back pressure chamber 100. The back pressure chamber 100 applies pressure in the direction of the piston 18 to the plurality of disks 51 via the pilot disk 52. In other words, the back pressure chamber 100 applies internal pressure to the damping valve 91 in the closing valve direction of seating on the valve seat portion 48. These plurality of disks 51, the pilot disk 52, and the back pressure chamber 100 constitute a part of the damping force 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 the passage in the passage groove 79 of the pilot case 55.

[0056] The passage in the notch 81 of the disk 50, the passage in the groove portion 30 of the piston rod 21, and the passage in the passage groove 79 of the pilot case 55 constantly communicate the first passage 43 of the piston 18 and the back pressure chamber 100 to introduce the hydraulic fluid L from the first passage 43 to the back pressure chamber 100. The damping force mechanism 41 on the extension side controls the opening of the damping valve 91 by the pressure of the back pressure chamber 100.

[0057] The disk valve 99 communicates the back pressure chamber 100 and the lower chamber 20 by separating from the valve seat portion 75. At that time, the disk valve 99 suppresses the flow of the hydraulic fluid L between it and the valve seat portion 75.

[0058] The disk valve 99 and the valve seat portion 75 constitute a damping force mechanism 110. When the disk valve 99 separates from the valve seat portion 75, the damping force mechanism 110 communicates the back pressure chamber 100 with the lower chamber 20. At this time, the damping force mechanism 110 suppresses the flow of the hydraulic fluid L between the back pressure chamber 100 and the lower chamber 20 to generate a damping force. In the extension stroke, the damping force mechanism 110 allows the hydraulic fluid L to flow from the upper chamber 19 to the lower chamber 20 through 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 back pressure chamber 100. The damping force mechanism 110 serves as a damping force generation mechanism on the extension side that suppresses the flow of the hydraulic fluid L from the back pressure chamber 100 to the lower chamber 20 generated in the extension stroke to generate a damping force.

[0059] On the valve seat portion 49 side in the axial direction of the piston 18, in the axial direction of the piston 18, in order from the piston 18 side, one disk 111, a plurality of (specifically, nine) disks 112, one disk 113, one disk 114, and one annular member 115 are provided. The disks 111 to 114 and the annular member 115 are all made of metal. The disks 111 to 114 and the annular member 115 are all perforated circular flat plates with a certain thickness. The disks 111 to 114 and the annular member 115 all have the mounting shaft portion 28 of the piston rod 21 fitted inside.

[0060] The disk 111 abuts on a portion radially inside the passage groove 40 of the piston 18. Among the plurality of disks 112, the disk 112 closest to the piston 18 in the axial direction abuts on the valve seat portion 49 of the piston 18. The plurality of disks 112 open and close the opening of the first passage 44 formed in the piston 18 by separating from and abutting on the valve seat portion 49.

[0061] A plurality of disks 112 constitute the disk valve 122. The disk valve 122 can be seated on and disengaged from the valve seat portion 49. The disk valve 122 can open the first passage 44 to the upper chamber 19 by disengaging from the valve seat portion 49. The space between the disk valve 122 and the valve seat portion 48 constitutes the first passage 44. When the disk valve 122 disengages from the valve seat portion 49 of the piston 18 and opens, the hydraulic fluid L from the first passage 44 flows into the upper chamber 19. At that time, the disk valve 122 suppresses the flow of the hydraulic fluid L between it and the valve seat portion 49. Therefore, the disk valve 122 suppresses the flow of the hydraulic fluid L from the lower chamber 20 to the upper chamber 19 via the first passage 44. The disk valve 122 and the valve seat portion 49 constitute the compression-side damping force mechanism 42. The disk valve 122 is formed with a fixed orifice 123 that communicates the first passage 44 with the upper chamber 19 even when it is in contact with the valve seat portion 49. The fixed orifice 123 also constitutes the damping force mechanism 42.

[0062] The disk 113 has an outer diameter smaller than the minimum outer diameter of the disk valve 122. The outer diameter of the disk 114 is larger than the outer diameter of the disk 113. The disk 114 and the annular member 115 contact the disk valve 122 when the disk valve 122 deforms in the opening direction, suppressing deformation of the disk valve 122 beyond a specified amount in the opening direction. The annular member 115 contacts the shaft step portion 29 of the piston rod 21.

[0063] A frequency-sensitive mechanism 130 (second damping force mechanism) is provided on the side of the disk 59 opposite to the disk 58 in the axial direction. 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).

[0064] As shown in FIG. 3, the frequency sensing mechanism 130 has a case member 131 on the side of the disk 59 in the axial direction. The frequency sensing mechanism 130 has, on the side opposite to the disk 59 in the axial direction of the case member 131, a plurality of (specifically, three) disks 132 having the same outer diameter and the same inner diameter, and a partition member 133. The frequency sensing mechanism 130 has, on the side opposite to the disk 59 in the axial direction of the disks 132 and the partition member 133, in order from the side of the disks 132 and the partition member 133, a plurality of (specifically, five) disks 135 having the same outer diameter and the same inner diameter, a plurality of (specifically, two) disks 136 having the same outer diameter and the same inner diameter, and a plurality of (specifically, two) disks 137 having the same outer diameter and the same inner diameter. An annular member 138 is provided on the side opposite to the disk 136 in the axial direction of the disk 137.

[0065] The plurality of disks 135 constitute a support member 141. The plurality of disks 136 constitute a valve seat member 142. The plurality of disks 137 constitute a lid member 143.

[0066] The case member 131, the disks 132, 135 to 137, and the annular member 138 are all made of metal. The disks 132, 135 to 137 and the annular member 138 are all perforated circular flat plates with a certain thickness. In other words, the disks 132, 135 to 137 and the annular member 138 are all formed from annular plate-like members. The disks 132, 135 to 137, the partitioning member 133, and the annular member 138 are all arranged on the radially inner side of the case member 131. The case member 131, the disks 132, 135 to 137, and the annular member 138 all fit the mounting shaft portion 28 of the piston rod 21 on the inside. Therefore, the case member 131, the disks 132, 135 to 137, and the annular member 138 all align with the piston rod 21 along the central axis. The partitioning member 133 allows the mounting shaft portion 28 of the piston rod 21 and a plurality of disks 132 to pass through on the inner peripheral side with a radial gap. The frequency sensing mechanism 130 is composed of the case member 131 and the disks 132, 135 to 137 to form the valve case 145. The frequency sensing mechanism 130 has the partitioning member 133 inside this valve case 145.

[0067] The case member 131 is a bottomed cylindrical shape. The case member 131 has a through hole 155 formed at the center in its radial direction, which penetrates the case member 131 in its axial direction. As shown in FIG. 2, in the axial direction of the through hole 155, the side closer to the piston 18 has a smaller diameter than the side opposite to the piston 18, and the mounting shaft portion 28 of the piston rod 21 is fitted into this smaller diameter portion.

[0068] As shown in FIG. 3, the case member 131 has a bottom portion 150, a protruding portion 151, a cylindrical portion 153, and a seat portion 154.

[0069] The bottom portion 150 is a perforated disk shape. The bottom portion 150 has a constant radial width over the entire circumference. The through hole 155 is formed in the bottom portion 150.

[0070] The protruding portion 151 is annular. The protruding portion 151 protrudes from the inner peripheral edge portion of the bottom portion 150 along the axial direction of the bottom portion 150 to the side opposite to the disk 59. A passage groove 158 that penetrates the protruding portion 151 in its radial direction is formed in the protruding portion 151. The passage in the passage groove 158 is a throttle and communicates with the passage in the groove portion 30 of the piston rod 21.

[0071] 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 portion of the bottom portion 150 along the axial direction of the bottom portion 150 to the same side as the protruding portion 151.

[0072] The sheet portion 154 is annular. The sheet portion 154 protrudes from the position between the protruding portion 151 and the cylindrical portion 153 in the radial direction of the bottom portion 150 along the axial direction of the bottom portion 150 to the same side as the protruding portion 151 and the cylindrical portion 153. A notch 159 that penetrates the tip portion on the protruding side in the radial direction of the sheet portion 154 is formed at the tip portion on the protruding side of the sheet portion 154. A plurality of notches 159 are formed in the sheet portion 154 at intervals in the circumferential direction of the sheet portion 154. Therefore, the tip portion on the protruding side of the sheet portion 154 is intermittently notched in the circumferential direction of the sheet portion 154. The height position of the tip of the sheet portion 154 in the axial direction of the bottom portion 150 is higher than the height position of the tip of the protruding portion 151.

[0073] The disk 132 has a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The outer diameter of the disk 132 is slightly smaller than the outer diameter of the end face on the side opposite to the bottom portion 150 in the axial direction of the protruding portion 151.

[0074] The disk 135 that constitutes the support member 141 has a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The outer diameter of the disk 135 is larger than the outer diameter of the disk 132.

[0075] The disk 136 that constitutes the valve seat member 142 has a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The outer diameter of the disk 136 is larger than the outer diameter of the disk 135.

[0076] The disk 137 that constitutes the lid member 143 has a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The outer diameter of the disk 137 is larger than the outer diameter of the disk 136.

[0077] The disks 132, 135 to 137, the partition member 133, and the annular member 138 are all arranged inside the cylindrical portion 153 in the radial direction. The disks 132, 135 to 137 and the partition member 133 are all arranged within the range of the cylindrical portion 153 in the axial direction of the cylindrical portion 153. A part of the annular member 138 is arranged within the range of the cylindrical portion 153 in the axial direction of the cylindrical portion 153, and the remaining part is arranged outside the range of the cylindrical portion 153 in the axial direction of the cylindrical portion 153.

[0078] The partition member 133 is composed of a valve disk 161 and an elastic seal member 162. The partition member 133 is arranged at a position radially between the cylindrical portion 153 of the case member 131 and the plurality of disks 132.

[0079] The valve disk 161 is made of metal. The valve disk 161 is a perforated circular flat plate with a certain thickness. The valve disk 161 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 plurality of disks 132 are inserted through the inner peripheral side of the valve disk 161. The valve disk 161 is elastically deformable, that is, bendable. The valve disk 161 has an inner diameter that allows the plurality of disks 132 to be arranged with a gap in the radial direction inside. The outer diameter of the valve disk 161 is smaller than the inner diameter of the cylindrical portion 153. The axial thickness of the valve disk 161 is thinner than the total thickness of all the disks 132.

[0080] The elastic sealing member 162 is made of rubber and is annular. The elastic sealing member 162 is adhered to the outer peripheral side of the valve disk 161. The elastic sealing member 162 is baked onto the valve disk 161 and provided integrally with the valve disk 161.

[0081] The elastic sealing member 162 has a sealing portion 165, a contact portion 166, and a valve closing portion 167. The sealing portion 165 is annular and is fixed to the entire circumference of the outer peripheral side of the valve disk 161. The sealing portion 165 protrudes from the valve disk 161 toward the bottom 150 side of the case member 131 in the axial direction of the partitioning member 133.

[0082] The contact portion 166 is annular and protrudes from the valve disk 161 to the side opposite to the bottom 150 in the axial direction of the partitioning member 133. The base end portion 170 of the contact portion 166 on the valve disk 161 side in the axial direction of the partitioning member 133 is fixed to the outer peripheral edge portion of the valve disk 161 by baking. The sealing portion 165 and the base end portion 170 of the contact portion 166 are connected and integrated on the outer peripheral side of the valve disk 161.

[0083] The outer diameter of the contact portion 166 becomes smaller as it moves away from the valve disk 161 in the axial direction of the partitioning member 133. The inner diameter of the inner peripheral portion of the tip end portion 171 of the contact portion 166 becomes larger as it moves away from the valve disk 161 in the axial direction of the partitioning member 133. Therefore, the tip end portion 171 of the contact portion 166 has a shape of a tapered single mountain shape that becomes thinner as it moves away from the valve disk 161 in the axial direction of the partitioning member 133 in the cross-section on the plane including the central axis of the partitioning member 133.

[0084] The contact portion 166 is formed with a notch portion 172 that penetrates the tip end portion 171 in the radial direction of the partitioning member 133 at the tip end portion 171. A plurality of notch portions 172 are formed in the contact portion 166 at intervals in the circumferential direction of the partitioning member 133. Therefore, the tip end portion 171 of the contact portion 166 is intermittently notched in the circumferential direction of the partitioning member 133.

[0085] The valve closing part 167 is annular and protrudes from the valve disk 161 to the side opposite to the bottom part 150 in the axial direction of the partitioning member 133. The valve closing part 167 is provided on the inner circumferential side of the contact part 166 in the radial direction of the partitioning member 133. The base end part 174 of the valve closing part 167 on the valve disk 161 side in the axial direction of the partitioning member 133 is fixed by baking inside the contact part 166 of the valve disk 161 in the radial direction of the partitioning member 133. The base end part 174 of the valve closing part 167 is connected to the base end part 170 of the contact part 166 and is integrated.

[0086] The inner circumferential part of the valve closing part 167 has a larger inner diameter as it is farther from the valve disk 161 in the axial direction of the partitioning member 133. The outer circumferential part of the tip end part 175 on the protruding side of the valve closing part 167 has a smaller outer diameter as it is farther from the valve disk 161 in the axial direction of the partitioning member 133. Therefore, the valve closing part 167 has a shape of a single tapered mountain shape where the cross-sectional shape in the plane including the central axis of the partitioning member 133 becomes thinner as it is farther from the valve disk 161 in the axial direction of the partitioning member 133. Therefore, the partitioning member 133 has a shape of two mountain shapes formed by the tip end part 171 of the contact part 166 and the tip end part 175 of the valve closing part 167. The cross-sectional shape of the tip end part 175 of the valve closing part 167 in the plane including the central axis of the partitioning member 133 is the same shape over the entire circumference. The protruding height of the valve closing part 167 from the valve disk 161 is lower than the protruding height of the contact part 166 from the valve disk 161.

[0087] Between the contact part 166 and the valve closing part 167 in the radial direction of the partitioning member 133, there is a concave part 176 for the elastic seal member 162. The concave part 176 is recessed toward the valve disk 161 side from the tip end part 171 of the contact part 166 and the tip end part 175 of the valve closing part 167 in the axial direction of the partitioning member 133. The concave part 176 is an annular shape continuous over the entire circumference of the partitioning member 133.

[0088] As described above, there is a radial gap between the partition member 133 and the plurality of disks 132. The partition member 133 is press-fitted into the cylindrical portion 153 of the case member 131 at its seal portion 165. By this press-fitting, the partition member 133 is centered so as to be coaxially arranged with respect to the case member 131, the plurality of disks 132, and the piston rod 21. At that time, the partition member 133 is in contact with the cylindrical portion 153 with a radial tightening margin over the entire circumference at the seal portion 165. In other words, the partition member 133 is in close contact with the cylindrical portion 153 of the case member 131 over the entire circumference at its seal portion 165. Therefore, the seal portion 165 is liquid-tightly fitted to the cylindrical portion 153 of the case member 131 over the entire circumference.

[0089] The seal portion 165 is slidable in the axial direction of the cylindrical portion 153 while remaining in close contact with the cylindrical portion 153 over the entire circumference. Therefore, the elastic seal member 162 always seals the gap between the partition member 133 and the cylindrical portion 153 with its seal portion 165. The seal portion 165 is radially outside the seat portion 154 of the case member 131. The partition member 133 has its valve disk 161 seated on the seat portion 154.

[0090] The disk 135 constituting the support member 141 has an outer diameter larger than the inner diameter of the valve disk 161, that is, the inner diameter of the partition member 133. The support member 141 is arranged on the side opposite to the bottom portion 150 in the axial direction of the valve disk 161 and is press-contacted with the first support portion 178 on the inner peripheral side of the valve disk 161 over the entire circumference. Thereby, the gap between the support member 141 and the valve disk 161, that is, the partition member 133, is closed.

[0091] As described above, the partition member 133 is centered with respect to the valve case 145 by the seal portion 165 contacting the cylindrical portion 153 over the entire circumference. In this state, for the partition member 133, the first support portion 178 on the inner peripheral side of its valve disk 161 is disposed between the protruding portion 151 and the support member 141 in the axial direction thereof. And one side surface of the first support portion 178 on the side opposite to the bottom portion 150 in the axial direction thereof abuts against the support member 141 and is supported by the support member 141. In other words, the partition member 133 has the first support portion 178 whose one side surface on the radially inner side is supported by the support member 141. The first support portion 178 is supported by the support member 141 only on one side surface without being clamped from both side surfaces. The partition member 133 is such that the first support portion 178 on the inner peripheral side of its valve disk 161 is movable within the range of the entire axial length of a plurality of (specifically, three) disks 132 between the protruding portion 151 and the support member 141.

[0092] For the partition member 133, the second support portion 179 disposed radially outside the first support portion 178 of its valve disk 161 abuts against the sheet portion 154 and is supported by the sheet portion 154 on one side surface on the bottom portion 150 side in the axial direction thereof. In other words, the partition member 133 has the second support portion 179 which is disposed radially outside the first support portion 178 and whose one side surface is supported by the sheet portion 154. The second support portion 179 is supported by the sheet portion 154 only on one side surface without being clamped from both side surfaces.

[0093] Therefore, the partition member 133 has a simple support structure in which one side surface of the first support portion 178 of its valve disk 161 is supported by the support member 141 and the other side surface of the second support portion 179 radially outside the first support portion 178 of the valve disk 161 is supported by the sheet portion 154. In other words, the valve disk 161 is not axially clamped.

[0094] The partition member 133 has the contact portion 166 disposed on the side opposite to the bottom portion 150 in the axial direction of the partition member 133. The contact portion 166 has the tip portion 171 disposed outside in the radial direction of the partition member 133 than the second support portion 179. The contact portion 166 is in contact with the lid member 143 composed of a plurality of disks 137 at the tip portion 171. The contact portion 166 biases the second support portion 179 side in the radial direction of the valve disk 161 toward the seat portion 154 side in the axial direction of the valve disk 161.

[0095] The partition member 133 has the valve closing portion 167 disposed on the side opposite to the bottom portion 150 in the axial direction of the partition member 133. The valve closing portion 167 has the tip portion 175 disposed slightly inside in the radial direction of the partition member 133 than the second support portion 179. The valve closing portion 167 has the tip portion 175 overlapping the valve seat member 142 composed of a plurality of disks 136 in the radial direction. In the axial direction of the partition member 133, when the valve disk 161 deforms, the valve closing portion 167 is displaced with respect to the valve seat member 142, and thereby, the tip portion 175 of the valve closing portion 167 comes into and out of contact with the valve seat member 142. Note that the partition member 133 is not limited to being displaced by deforming in its axial direction, and may be displaced by moving in its axial direction.

[0096] The partition member 133 is in the shape of an annular plate as a whole and is elastically deformable, that is, bendable, as a whole. The valve disk 161 of the partition member 133 is bendable in a tapered shape such that the second support portion 179 moves away from the seat portion 154 while maintaining the state where the first support portion 178 is in contact with the support member 141. When bending in this way, the valve disk 161 bends so as to move the second support portion 179 to the side opposite to the bottom portion 150 more than the first support portion 178 in the axial direction of the case member 131. At that time, the valve disk 161 elastically deforms the contact portion 166 that contacts the lid member 143. Then, when bending by a predetermined amount, the valve disk 161 brings the tip portion 175 of the valve closing portion 167 into contact with the valve seat member 142.

[0097] The plurality of disks 137 that constitute the lid member 143 have an outer diameter larger than the outer diameter of the disk 136 and smaller than the inner diameter of the cylindrical portion 153. The lid member 143 has its inner peripheral side in contact with the disk 136 and the annular member 138, and its outer peripheral side in contact with the contact portion 166 of the partitioning member 133. The lid member 143 suppresses movement in the direction opposite to the bottom portion 150 in the axial direction of the partitioning member 133.

[0098] The seat portion 154 of the case member 131 supports the second support portion 179 of the valve disk 161 of the partitioning member 133 from one axial side. The support member 141 supports the first support portion 178 on the inner peripheral side of the valve disk 161 relative to the seat portion 154 from the other axial side. The shortest axial distance between the seat portion 154 and the support member 141 is slightly smaller than the axial thickness of the valve disk 161. Therefore, the valve disk 161 is press - contacted with both the seat portion 154 and the support member 141 by its own elastic force in a slightly elastically deformed state.

[0099] The partitioning member 133 is provided in the valve case 145 and partitions the inside of the valve case 145 into a first chamber 181 and a second chamber 182. The first chamber 181 is between the bottom portion 150 and the partitioning member 133 in the axial direction of the valve case 145. In other words, the first chamber 181 is on the bottom - portion 150 side rather than the partitioning - member 133 side in the axial direction of the valve case 145. The second chamber 182 is between the partitioning member 133 and the valve seat member 142 and the lid member 143 in the axial direction of the valve case 145. In other words, the second chamber 182 is on the side opposite to the bottom portion 150, that is, the opening side of the case member 131, rather than the partitioning - member 133 side in the axial direction of the valve case 145.

[0100] Both the first chamber 181 and the second chamber 182 have variable volumes, and their volumes change with the displacement caused by the deformation of the partitioning member 133. The first chamber 181 is constantly in communication with the passage in the groove portion 30 of the piston rod 21 through the passage in the passage groove 158 of the case member 131. The first chamber 181 is constantly in communication with the upper 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, and the first passage 43. Also, the first chamber 181 is constantly in communication with the back pressure chamber 100 through the passage in the passage groove 158 shown in FIG. 3, the passage in the groove portion 30, and the passage in the passage groove 79 shown in FIG. 2.

[0101] As shown in FIG. 3, when the valve closing portion 167 of the partitioning member 133 is separated from the valve seat member 142, the entire second chamber 182 communicates with the lower chamber 20 through the passage portion 185 between the lid member 143 and the cylindrical portion 153 of the case member 131.

[0102] As shown in FIG. 4, when the partitioning member 133 is deformed so that the valve closing portion 167 is in contact with the valve seat member 142 over the entire circumference, the second chamber 182 is partitioned into a pressure chamber 187 radially inside the valve closing portion 167 and a communication chamber 188 radially outside the valve closing portion 167. The communication chamber 188 communicates with the lower chamber 20 through the passage portion 185. The pressure chamber 187 does not communicate with the communication chamber 188 and thus does not communicate with the lower chamber 20 either.

[0103] During the extension stroke, the hydraulic fluid L from the upper chamber 19 shown in FIG. 2 is introduced into the first chamber 181 through 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, and the passage in the passage groove 158 of the case member 131 shown in FIG. 3. Then, the valve disk 161 of the partitioning member 133 bends in a tapered shape so as to separate the second support portion 179 from the bottom portion 150 in the axial direction of the case member 131 with the contact point with the support member 141 that contacts at the first support portion 178 as a fulcrum. At that time, the valve disk 161 causes the contact portion 166 that contacts the lid member 143 to be compressed and deformed in the axial direction of the case member 131.

[0104] Due to the displacement of the partition member 133 including the valve disk 161 as described above, the partition member 133 will increase the volume of the first chamber 181. Here, when the partition member 133 is displaced, the volume of the second chamber 182 will decrease. At this time, the hydraulic fluid L in the second chamber 182 flows into the lower chamber 20 through the passage portion 185.

[0105] Here, in the extension stroke, when the displacement of the partition member 133 is smaller than a predetermined amount, the closing valve portion 167 is separated from the valve seat member 142. Therefore, the hydraulic fluid L flows from the entire second chamber 182 into the lower chamber 20 through the passage portion 185.

[0106] On the other hand, in the extension stroke, when the displacement of the partition member 133 is equal to or greater than a predetermined amount, as shown in FIG. 4, the closing valve portion 167 abuts against the valve seat member 142 over the entire circumference, partitioning the second chamber 182 into a pressure chamber 187 and a communication chamber 188. Therefore, although the communication chamber 188 communicates with the lower chamber 20 through the passage portion 185, the pressure chamber 187 is in a state of not communicating with the lower chamber 20.

[0107] That is, the frequency sensing mechanism 130 causes the valve disk 161 of the partition member 133 to be displaced by the hydraulic fluid L flowing into the first chamber 181 due to the movement of the piston 18 in the extension stroke, and discharges at least a part of the hydraulic fluid L in the second chamber 182 into the lower chamber 20 in the cylinder 2. Further, as shown in FIG. 4, the frequency sensing mechanism 130 forms a closed pressure chamber 187 between the valve seat member 142 in the second passage 191 and the partition member 133, and restricts the movement of the hydraulic fluid L in the pressure chamber 187.

[0108] As shown in FIG. 2, 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 the second passage 191. The second passage 191 is constantly in communication with the upper chamber 19 by 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. In the second passage 191, the passage portion 185 and the second chamber 182 are in communication with the lower chamber 20. The second passage 191 is a passage through which the hydraulic fluid L moves from the upper chamber 19, which is the upstream side in the extending stroke, toward the lower chamber 20, which is the downstream side. The second passage 191 is a passage through which the hydraulic fluid L moves from the lower chamber 20, which is the upstream side in the contracting stroke, toward the upper chamber 19, which is the downstream side. The frequency-sensitive mechanism 130 has a partitioning member 133 provided in this second passage 191. The partitioning member 133 partitions the second passage 191 between the first chamber 181 and the second chamber 182.

[0109] In the second passage 191, the passage holes 37 and the passages in the passage grooves 38 in the piston 18 are common to the first passage 43. The second passage 191 is provided in parallel with the passage between the damping valve 91 and the valve seat portion 48 in the first passage 43 between the upper chamber 19 and the lower chamber 20 by the passage in the notch 81, the passage in the groove portion 30, the passage in the passage groove 158, the first chamber 181, the second chamber 182, and the passage portion 185. The second passage 191 is provided in parallel with the first passage 44 between the lower chamber 20 and the upper chamber 19. Therefore, the second passage 191 is formed in parallel with the first passages 43 and 44 and is provided so that the hydraulic fluid L in both the upper chamber 19 and the lower chamber 20 can flow in due to the movement of the piston 18. Note that the second passage 191 may be provided so that the hydraulic fluid L in only one of the upper chamber 19 and the lower chamber 20 can flow in. That is, the second passage 191 may be provided so that the hydraulic fluid L in at least one of the upper chamber 19 and the lower chamber 20 can flow in.

[0110] The pressure chamber 187 shown in FIG. 4 is formed by the contact between the valve closing portion 167 and the valve seat member 142 in the second passage 191 due to the displacement of the partitioning member 133. The valve closing portion 167 is provided on the partitioning member 133 and is formed by an elastic member that contacts the valve seat member 142 of the second passage 191 after the displacement of the partitioning member 133 and deforms so that the partitioning member 133 can still be displaced after the contact.

[0111] The partitioning member 133 is displaceable in the axial direction toward the bottom portion 150 between the case member 131 and the support member 141 at the inner peripheral side of its valve disk 161. As shown in FIGS. 3 and 4, when the first support portion 178 of the valve disk 161 of the partitioning member 133 is in contact with the support member 141 over the entire circumference, the flow of the oil fluid L between the first chamber 181 and the second chamber 182 is blocked. Also, when the first support portion 178 of the valve disk 161 of the partitioning member 133 is axially separated from the support member 141, the partitioning member 133 allows the flow of the oil fluid L between the second chamber 182 and the first chamber 181. The first support portion 178 of the valve disk 161 and the support member 141 constitute a check valve 193. The check valve 193 is provided in the second passage 191.

[0112] The check valve 193 restricts the flow of the oil fluid L from the first chamber 181 to the second chamber 182 through the second passage 191 while allowing the flow of the oil fluid L from the second chamber 182 to the first chamber 181 through the second passage 191. The check valve 193 blocks the communication between the upper chamber 19 and the lower chamber 20 through the second passage 191 during the extension stroke when the pressure in the upper chamber 19 is higher than the pressure in the lower chamber 20. The check valve 193 connects the lower chamber 20 and the upper chamber 19 through the second passage 191 during the compression stroke when the pressure in the lower chamber 20 is higher than the pressure in the upper chamber 19. In this way, the second passage 191 connects the lower chamber 20 and the upper chamber 19 when the check valve 193 opens.

[0113] As shown in Fig. 2, on the piston rod 21, with the mounting shaft portions 28 inserted into the respective inner sides, an annular member 115, a disk 114, a disk 113, a plurality of disks 112, a disk 111, a piston 18, a plurality of disks 50, a plurality of disks 51, a pilot disk 52, a disk 53, a pilot case 55, a disk 56, a plurality of disks 57, a disk 58, and a disk 59 are stacked on the shaft step portion 29 in this order. At this time, the pilot case 55 fits the seal member 86 of the pilot disk 52 onto the outer cylindrical portion 73.

[0114] From this state, as shown in Fig. 3, with the mounting shaft portion 28 inserted into the inner side, a case member 131 is stacked on the disk 59. From this state, with the mounting shaft portions 28 inserted into the respective inner sides, a plurality of disks 132 are stacked on the disk 59. At the same time, a partition member 133 is stacked on the sheet portion 154 of the case member 131 at the valve disk 161 so as to insert the mounting shaft portion 28 and the plurality of disks 132 into the inner side. At this time, the elastic seal member 162 of the partition member 133 is fitted onto the cylindrical portion 153 of the case member 131.

[0115] Furthermore, with the mounting shaft portions 28 inserted into the respective inner sides, a plurality of disks 135, a plurality of disks 136, a plurality of disks 137, and an annular member 138 are stacked on the disk 132 and the valve disk 161 of the partition member 133 in this order.

[0116] As shown in Fig. 2, with the components from the annular member 115 to the annular member 138 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 from the annular member 138. Therefore, the components from the annular member 115 to the annular member 138 are each clamped axially with their inner peripheral sides or all being sandwiched between the shaft step portion 29 of the piston rod 21 and the nut 195. At that time, the partition member 133 is not axially clamped including its inner peripheral side. In this state, as shown in Fig. 3, for the partition member 133, the first support portion 178 of the valve disk 161 abuts against the support member 141, the second support portion 179 abuts against the seat portion 154 of the case member 131, and the contact portion 166 of the elastic seal member 162 abuts against the lid member 143.

[0117] As shown in Fig. 1, between the bottom portion 12 of the outer cylinder 4 and the inner cylinder 3, the above-described base valve 25 is provided. This base valve 25 has a base partition member 221, a disk valve 222, a disk valve 223, and a mounting pin 224. For the base valve 25, the base partition member 221 is placed on the bottom portion 12, and the base partition member 221 is fitted into the inner cylinder 3. The base partition member 221 partitions the lower chamber 20 and the reservoir chamber 6. The disk valve 222 is provided on the lower side of the base partition member 221, that is, on the reservoir chamber 6 side. The disk valve 223 is provided on the upper side of the base partition member 221, that is, on the lower chamber 20 side. The mounting pin 224 attaches the disk valve 222 and the disk valve 223 to the base partition member 221.

[0118] The base partition member 221 is annular, and a mounting pin 224 is inserted through the center in the radial direction. A plurality of passage holes 225 and a plurality of passage holes 226 are formed in the base partition member 221. The plurality of passage holes 225 allow the oil fluid L to flow between the lower 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 partition member 221. The plurality of passage holes 226 allow the oil fluid L to flow between the lower chamber 20 and the reservoir chamber 6. The disk valve 222 on the reservoir chamber 6 side allows the flow of the oil fluid L from the lower chamber 20 to the reservoir chamber 6 through the passage hole 225. On the other hand, the disk valve 222 suppresses the flow of the oil fluid L from the reservoir chamber 6 to the lower chamber 20 through the passage hole 225. The disk valve 223 allows the flow of the oil fluid L from the reservoir chamber 6 to the lower chamber 20 through the passage hole 226. On the other hand, the disk valve 223 suppresses the flow of the oil fluid L from the lower chamber 20 to the reservoir chamber 6 through the passage hole 226.

[0119] The disk valve 222 and the base partition member 221 constitute a damping valve mechanism 227. The damping valve mechanism 227 opens during the compression stroke of the shock absorber 1 to allow the oil fluid L to flow from the lower chamber 20 to the reservoir chamber 6 and generate a damping force. The disk valve 223 and the base partition member 221 constitute a suction valve mechanism 228. The suction valve mechanism 228 opens during the extension stroke of the shock absorber 1 to allow the oil fluid L to flow from the reservoir chamber 6 into the lower chamber 20. Note that the suction valve mechanism 228 mainly functions to supply the oil fluid L from the reservoir chamber 6 to the lower chamber 20 to compensate for the shortage of the fluid caused by the extension of the piston rod 21 from the cylinder 2, and flows the oil fluid L without substantially generating a damping force.

[0120] Next, the main operation of the shock absorber 1 will be described.

[0121] "When it is assumed that in the extension stroke, the frequency-sensitive mechanism 130 does not act and only the extension-side damping force mechanism 41 and the damping force mechanism 110 act"

[0122] In this case, when the moving speed of the piston 18 (hereinafter referred to as the piston speed) is slower than the first predetermined value, the oil L from the upper chamber 19 flows into the lower chamber 20 through the first passage 43 shown in FIG. 2 and the fixed orifice 92 of the damping force mechanism 41. Therefore, a damping force with orifice characteristics (the damping force is approximately proportional to the square of the piston speed) is generated. For this reason, the characteristic of the damping force with respect to the piston speed when the piston speed is slower than the first predetermined value is such that the rising rate of the damping force with respect to the increase in the piston speed becomes relatively high.

[0123] 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 upper chamber 19 passes through 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, and while opening the disk valve 99 of the damping force mechanism 110, flows into the lower chamber 20 through the space between the disk valve 99 and the valve seat portion 75. Therefore, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) is generated. For this reason, 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 such that the rising rate of the damping force with respect to the increase in the piston speed is lower than when the piston speed is less than the first predetermined value.

[0124] When the piston speed becomes faster than the second predetermined value, the relationship of the force (hydraulic pressure) acting on the damping valve 91 of the damping force mechanism 41 is such that the opening-direction force applied from the first passage 43 is greater than the closing-direction force applied from the back pressure chamber 100. Therefore, in this region, as the piston speed increases, the damping valve 91 moves away from the valve seat portion 48 of the piston 18 and opens. Therefore, in addition to the flow of the oil L from the upper chamber 19 into the lower chamber 20 through the space between the disk valve 99 and the valve seat portion 75 while opening the disk valve 99 described above, while opening the damping valve 91, the oil L flows from the first passage 43 through the space between the damping valve 91 and the valve seat portion 48 into the lower chamber 20. For this reason, the rising 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.

[0125] "When it is assumed that in the compression stroke, the frequency-sensitive mechanism 130 does not act and only the compression-side damping force mechanism 42 acts"

[0126] In this case, when the piston speed is slower than the third predetermined value, the hydraulic fluid L from the lower chamber 20 flows into the upper chamber 19 through the first passage 44 and the fixed orifice 123 of the damping force mechanism 42. Therefore, a damping force with orifice characteristics is generated. For this reason, 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 the increase in the piston speed is relatively high.

[0127] When the piston speed becomes faster than the third predetermined value, the hydraulic fluid L introduced from the lower chamber 20 into the first passage 44 flows into the upper chamber 19 through between the disk valve 122 and the valve seat portion 49 while opening the disk valve 122 of the damping force mechanism 42. Therefore, a damping force with valve characteristics is generated. For this reason, the characteristic of the damping force with respect to the piston speed when the piston speed is equal to or higher than the third predetermined value is that the rate of increase of the damping force with respect to the increase in the piston speed is lower than when the piston speed is less than the third predetermined value.

[0128] "When the frequency-sensitive mechanism 130 acts in the extension stroke"

[0129] In the first embodiment, the frequency-sensitive mechanism 130 makes the damping force variable according to the piston frequency even when the piston speed is the same. The frequency-sensitive mechanism 130 is a flow rate variable mechanism that makes the flow rate of the hydraulic fluid flowing into the damping force mechanisms 41 and 110 variable according to the piston frequency even when the piston speed is the same.

[0130] During the extension stroke, the hydraulic fluid L is introduced from the upper chamber 19 into the first chamber 181 of the frequency sensing mechanism 130 through 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 shown in FIG. 3. Therefore, the valve disk 161 of the partition member 133 that was in contact with the seat portion 154 and the support member 141 is tapered and deformed in a direction away from the seat portion 154 on the outer peripheral side with the contact point with the support member 141 as a fulcrum due to the pressure load. At this time, the valve disk 161 mainly compresses and deforms the tip portion 171 of the contact portion 166 that contacts the lid member 143.

[0131] Here, during the extension stroke when the piston frequency is high, the stroke of the piston 18 is small. For this reason, the amount of the hydraulic fluid L introduced from the upper chamber 19 shown in FIG. 2 into the first chamber 181 through 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 partition member 133 is deformed as described above due to the pressure load, the amount of deformation is small. Thus, during the extension stroke when the piston frequency is high, each time the extension stroke occurs, the partition member 133 of the frequency sensing mechanism 130 is deformed as described above, and the hydraulic fluid L is introduced from the upper chamber 19 into the first chamber 181. Then, the flow rate of the hydraulic fluid L flowing from the upper chamber 19 through 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 back pressure chamber 100 and opening the damping force mechanism 110 to the lower chamber 20 will decrease. In addition to this, the flow rate of the hydraulic fluid L flowing from the first passage 43 and opening the damping force mechanism 41 to the lower chamber 20 will also decrease. In addition, by introducing the hydraulic fluid L from the upper chamber 19 into the first chamber 181, the pressure rise in the back pressure chamber 100 is suppressed compared to the case where there is no first chamber 181, and the damping valve 91 of the damping force mechanism 41 is more likely to open. As a result, the damping force on the extension side becomes soft.

[0132] During the extension stroke when the piston frequency is high, as described above, the deformation amount of the partition member 133 is small. In other words, during the extension stroke when the piston frequency is high, the pressure difference between the first chamber 181 and the second chamber 182 with respect to the partition member 133 is small. That is, the displacement of the partition member 133 toward the lid member 143 side becomes the first displacement whose displacement amount is equal to or less than a predetermined value, and the closing valve portion 167 shown in FIG. 3 does not close the flow path between the valve seat member 142, or even if it closes, the pressure difference between the first chamber 181 and the second chamber 182 with respect to the partition member 133 does not become excessive. When the closing valve portion 167 does not close the flow path between the valve seat member 142, the partition member 133 easily displaces by discharging the entire oil fluid L in the second chamber 182 of the frequency sensitive mechanism 130 to the lower chamber 20 through the passage portion 185.

[0133] On the other hand, during the extension stroke when the piston frequency is low, the stroke of the piston 18 is large. For this reason, the amount of the oil fluid L introduced into the first chamber 181 from the upper chamber 19 shown in FIG. 2 through 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 large. Therefore, at the initial stage of the stroke of the piston 18, the oil fluid L flows from the upper chamber 19 to the first chamber 181, but thereafter, the partition member 133 deforms to near the limit and no longer deforms. As a result, the oil fluid L no longer flows from the upper chamber 19 to the first chamber 181. Therefore, the flow rate of the oil fluid L flowing from the upper chamber 19 through 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 back pressure chamber 100 and opening the damping force mechanism 110 to the lower chamber 20 does not decrease. In addition to this, the flow rate of the oil fluid L flowing from the first passage 43 and opening the damping force mechanism 41 to the lower chamber 20 also does not decrease. In addition, since the oil fluid L is not introduced from the upper chamber 19 into the first chamber 181, the pressure in the back pressure chamber 100 rises, and it becomes difficult for the damping valve 91 of the damping force mechanism 41 to open. As a result, the damping force on the extension side becomes harder than that at high frequencies.

[0134] Here, at the initial stage of the extension stroke when the piston frequency is low, and when the displacement of the partition member 133 toward the lid member 143 side is a first displacement with a displacement amount equal to or less than a predetermined value, the closing valve portion 167 shown in FIG. 3 does not contact the valve seat member 142, or even if it contacts the valve seat member 142, it does not close the flow path between the valve seat member 142. Therefore, the partition member 133 is easily displaced by discharging the entire hydraulic fluid L in the second chamber 182 of the frequency sensing mechanism 130 to the lower chamber 20 through the passage portion 185.

[0135] On the other hand, after the above initial stage of the extension stroke when the piston frequency is low, the pressure difference between the first chamber 181 and the second chamber 182 increases, the pressure load on the partition member 133 increases, and the displacement of the partition member 133 toward the lid member 143 side becomes a second displacement with a displacement amount exceeding the predetermined value. Then, as shown in FIG. 4, the closing valve portion 167 contacts the valve seat member 142 over the entire circumference and closes the flow path between the valve seat member 142. In this state, a pressure chamber 187 is formed in which the radially inner side of the closing valve portion 167 of the second chamber 182 is sealed, and the hydraulic fluid L in the pressure chamber 187 is not discharged to the communication chamber 188. In the state where the pressure chamber 187 is thus closed, the pressure in the pressure chamber 187 also increases as the pressure in the first chamber 181 increases. Therefore, the partition member 133 is suppressed from having an enlarged pressure difference between the first chamber 181 side and the second chamber 182 side of the radially inner side portion than the closing valve portion 167. Therefore, the partition member 133 is suppressed from having a large deformation on the first support portion 178 side that contacts the support member 141 of the valve disk 161 and an increase in stress on the first support portion 178 side.

[0136] During the compression stroke, the pressure in the lower chamber 20 increases, but the valve disk 161 of the partitioning 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. For this reason, the amount of the hydraulic fluid L introduced from the lower chamber 20 into the second chamber 182 through the passage portion 185 is suppressed. As a result, the flow rate of the hydraulic fluid L introduced from the lower chamber 20 into the first passage 44 shown in FIG. 2, passing through the damping force mechanism 42, and flowing into the upper chamber 19 does not decrease. During the compression stroke, when the piston speed increases and the pressure in the second chamber 182 becomes higher than a predetermined value or more than the pressure in the first chamber 181, the partitioning member 133 has the first support portion 178 of the valve disk 161 separated from the support member 141. In other words, the check valve 193 opens. Therefore, the hydraulic fluid L flows from the lower chamber 20 into the upper chamber 19 through 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, and the first passage 43. Thus, when the check valve 193 opens, the partitioning member 133 suppresses the differential pressure between the second chamber 182 side and the first chamber 181 side. Therefore, excessive deflection of the partitioning member 133 is suppressed.

[0137] Patent Document 1 described above discloses a shock absorber in which damping force characteristics vary according to a vibration state. By the way, in a shock absorber in which damping force characteristics vary according to a vibration state, a partitioning member that displaces while partitioning a passage may be used, and it is desired to improve the durability of this partitioning member.

[0138] In the shock absorber 1 of the first embodiment, a second passage 191 is provided in parallel to a first passage 43 provided with a first damping force mechanism 41 that generates a damping force, and at least one of the upper chamber 19 and the lower chamber 20 can be filled with the hydraulic fluid L by the movement of the piston 18. The shock absorber 1 is provided with a frequency-sensitive mechanism 130 that varies the damping force in the second passage 191. The frequency-sensitive mechanism 130 has a partitioning member 133 that partitions the second passage 191, is displaced by the hydraulic fluid L flowing in due to the movement of the piston 18, and discharges at least a part of the hydraulic fluid L in the second passage 191 into the cylinder 2. Further, the frequency-sensitive mechanism 130 forms a pressure chamber 187 closed between a valve seat member 142 in the second passage 191 and the partitioning member 133, and has a valve closing portion 167 that restricts the movement of the hydraulic fluid L in the pressure chamber 187. In other words, in the shock absorber 1, the valve closing portion 167 forms a pressure chamber 187 closed between the inside of the second passage 191 and the partitioning member 133.

[0139] Therefore, when the pressure in the first chamber 181 on the side opposite to the pressure chamber 187 of the partitioning member 133 in the second passage 191 increases in the shock absorber 1, the pressure in the pressure chamber 187 increases following this, and the displacement of the partitioning member 133 is suppressed. In this way, since the shock absorber 1 can suppress the displacement of the partitioning member 133, the durability of the partitioning member 133 can be improved. Further, since the shock absorber 1 suppresses the displacement of the partitioning member 133 by the pressure of the hydraulic fluid L, it can suppress the generation of abnormal noise that easily occurs when suppressing with metal parts. Further, when suppressing the displacement of the partitioning member 133, the shock absorber 1 can be gently suppressed by the pressure of the hydraulic fluid L, so that it can suppress a deterioration in the riding comfort caused by a sudden change in the damping force.

[0140] Further, in the shock absorber 1, the pressure chamber 187 is formed by the displacement of the partition member 133 causing the valve seat member 142 and the valve closing portion 167 in the second passage 191 to come into contact with each other. The shock absorber 1 can thus form the pressure chamber 187 by the displacement of the partition member 133. Therefore, the shock absorber 1 can easily displace the partition member 133 without forming the pressure chamber 187 by the displacement of the partition member 133 to vary the damping force, or can form the pressure chamber 187 to suppress the displacement of the partition member 133.

[0141] Further, in the shock absorber 1, the valve closing portion 167 is provided on the partition member 133 and is formed by an elastic member that comes into contact with the valve seat member 142 in the second passage 191 after the displacement of the partition member 133 and deforms so that the partition member 133 can still be displaced after the contact. Since the valve closing portion 167 is provided on the partition member 133 in the shock absorber 1, the pressure chamber 187 can be easily formed by the displacement of the partition member 133.

[0142] Further, since the valve closing portion 167 in the shock absorber 1 deforms so that the partition member 133 can still be displaced after coming into contact with the valve seat member 142, when suppressing the displacement of the partition member 133, it can be suppressed more gently. Therefore, the shock absorber 1 can further suppress the generation of abnormal noise and can further suppress the deterioration of the riding comfort caused by a sudden change in the damping force.

[0143] [Second Embodiment] Next, the second embodiment will be mainly described focusing on the differences from the first embodiment based on FIG. 5. For parts common to the first embodiment, the same names and the same reference numerals are used.

[0144] As shown in FIG. 5, the shock absorber 1A of the second embodiment has a frequency-sensitive mechanism 130A (second damping force mechanism) that is partially different from the frequency-sensitive mechanism 130 instead of the frequency-sensitive mechanism 130.

[0145] The frequency sensing mechanism 130A has a partition member 133A that is partially different from the partition member 133 in place of the partition member 133. The partition member 133A has an elastic seal member 162A that is partially different from the elastic seal member 162 in place of the elastic seal member 162. The elastic seal member 162A has a contact portion 166A that is partially different from the contact portion 166 in place of the contact portion 166. The elastic seal member 162A has a valve closing portion 167A that is partially different from the valve closing portion 167 in place of the valve closing portion 167.

[0146] The contact portion 166A is annular, and the base end portion 170A on the valve disk 161 side in the axial direction of the partition member 133A is fixed to the outer peripheral side of the valve disk 161 by baking.

[0147] The inner peripheral portion of the contact portion 166A has an inner diameter that increases as it moves away from the valve disk 161 in the axial direction of the partition member 133A. The outer peripheral portion of the tip end portion 171A on the protruding side of the contact portion 166A has an outer diameter that decreases as it moves away from the valve disk 161 in the axial direction of the partition member 133A. Therefore, the contact portion 166A has a shape of a single tapered mountain shape in which the tip end portion 171A becomes thinner as it moves away from the valve disk 161 in the axial direction of the partition member 133A in the cross-sectional shape on the plane including the central axis of the partition member 133A.

[0148] The contact portion 166A has a notch portion 172A formed in the tip end portion 171A that penetrates the tip end portion 171A in the radial direction of the partition member 133A. A plurality of notch portions 172A are formed in the contact portion 166A at intervals in the circumferential direction of the partition member 133A. Therefore, the tip end portion 171A of the contact portion 166A is intermittently notched in the circumferential direction of the partition member 133A.

[0149] The valve closing part 167A is annular and is provided outside the contact part 166A in the radial direction of the partitioning member 133A. The base end part 174A of the valve closing part 167A on the valve disk 161 side in the axial direction of the partitioning member 133A is fixed to the outer peripheral edge part of the valve disk 161 in the radial direction by baking. On the outer peripheral side of the valve disk 161, the seal part 165 and the base end part 174A of the valve closing part 167A are connected and integrated. The valve closing part 167A is integrated with the base end part 174A being connected to the base end part 170A of the contact part 166A.

[0150] The outer peripheral part of the valve closing part 167A has a smaller outer diameter as it is farther from the valve disk 161 in the axial direction of the partitioning member 133A. The inner peripheral part of the tip end part 175A on the protruding side of the valve closing part 167A has a smaller outer diameter as it is farther from the valve disk 161 in the axial direction of the partitioning member 133A. Therefore, the valve closing part 167A has a shape of a single tapered mountain shape where the cross-sectional shape in the plane including the central axis line of the partitioning member 133A becomes thinner as it is farther from the valve disk 161 in the axial direction of the partitioning member 133A. Therefore, the partitioning member 133A has a shape of two mountain shapes formed by the tip end part 171A of the contact part 166A and the tip end part 175A of the valve closing part 167A. The cross-sectional shape of the tip end part 175A of the valve closing part 167A in the plane including the central axis line of the partitioning member 133A is the same shape over the entire circumference. The protruding height of the valve closing part 167A from the valve disk 161 is lower than the protruding height of the contact part 166A from the valve disk 161.

[0151] Between the contact part 166A and the valve closing part 167A in the radial direction of the partitioning member 133A, there is a recessed part 176A for the elastic seal member 162A. The recessed part 176A is recessed toward the valve disk 161 side from the tip end part 171A of the contact part 166A and the tip end part 175A of the valve closing part 167A in the axial direction of the partitioning member 133A. The recessed part 176A is an annular shape continuous over the entire circumference of the partitioning member 133A.

[0152] The frequency sensing mechanism 130A has a valve case 145A that is partially different from the valve case 145 in place of the valve case 145. The valve case 145A has a support member 141A that is partially different from the support member 141 in place of the support member 141. The number of discs 135 of the support member 141A is different from that of the support member 141. The support member 141A is composed of a plurality of (specifically, seven) discs 135 having the same outer diameter and the same inner diameter. The valve case 145A is not provided with a plurality of discs 136 that constitute the valve seat member 142. Instead of these discs 136, the number of discs 135 that constitute the support member 141A is increased with respect to the support member 141. The support member 141A is thicker in the axial direction than the support member 141.

[0153] A valve seat member 142A is provided at the outer peripheral edge portion on the support member 141A side in the axial direction of the lid member 143 of the valve case 145A. The valve seat member 142A is a perforated disc-shaped member having a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The valve seat member 142A is coaxially arranged and fixed by adhesion or the like to the outer peripheral edge portion of the disc 137 at the end portion on the support member 141A side in the axial direction among the discs 137 that constitute the lid member 143.

[0154] The partition member 133A has a contact portion 166A and a valve closing portion 167A disposed on the side opposite to the bottom portion 150 in the axial direction of the partition member 133A. The contact portion 166A contacts the lid member 143 composed of a plurality of discs 137 at the tip portion 171A. The contact portion 166A biases the second support portion 179 side in the radial direction of the valve disc 161 toward the seat portion 154 side in the axial direction of the valve disc 161.

[0155] The partition member 133A is arranged such that the valve closing portion 167A is on the side opposite to the bottom portion 150 in the axial direction of the partition member 133A. The valve closing portion 167A has its tip portion 175A overlapping the positions of the valve seat member 142A and the partition member 133A in the radial direction. In the axial direction of the partition member 133A, when the valve disk 161 of the partition member 133A deforms, the valve closing portion 167A is displaced with respect to the valve seat member 142A, whereby the tip portion 175A of the valve closing portion 167A comes into and out of contact with the valve seat member 142A. Note that the partition member 133A is not limited to being displaced in the axial direction by deforming, and may be displaced in the axial direction by moving.

[0156] The valve disk 161 of the partition member 133A can be bent in a tapered shape such that the second support portion 179 moves away from the seat portion 154 while maintaining the state where the first support portion 178 is in contact with the support member 141. When bending in this way, the valve disk 161 elastically deforms the contact portion 166A that contacts the lid member 143. Then, when bent by a predetermined amount, the valve disk 161 brings the tip portion 175A of the valve closing portion 167A into contact with the valve seat member 142A.

[0157] The partition member 133A is provided in the valve case 145A and divides the inside of the valve case 145A into a first chamber 181 and a second chamber 182. The first chamber 181 is between the bottom portion 150 in the axial direction of the valve case 145A and the partition member 133A. The second chamber 182 is between the partition member 133A and the lid member 143 in the axial direction of the valve case 145A.

[0158] As shown in FIG. 5, in a state where the valve closing portion 167A of the partition member 133A is separated from the valve seat member 142A, the entire second chamber 182 communicates with the lower chamber 20 through a passage portion 185 between the lid member 143 and the cylindrical portion 153 of the case member 131.

[0159] When the partition member 133A is deformed into a tapered shape and its valve closing portion 167A is in contact with the valve seat member 142A over the entire circumference, the second chamber 182 is partitioned into a pressure chamber radially inside the valve closing portion 167A and a communication chamber radially outside the valve closing portion 167A. This communication chamber communicates with the lower chamber 20 via the passage portion 185. This pressure chamber does not communicate with the communication chamber and thus does not communicate with the lower chamber 20 either.

[0160] In the extension stroke, the hydraulic fluid L from the upper chamber 19 (see FIG. 2) passes through the first passage 43 (see FIG. 2), the passage in the notch 81 (see FIG. 2) of the disk 50 (see FIG. 2), the passage in the groove portion 30 of the piston rod 21 shown in FIG. 5, and the passage in the passage groove 158 of the case member 131 and is introduced into the first chamber 181. Then, the valve disk 161 of the partition member 133A deflects in a tapered shape so as to separate the second support portion 179 from the bottom portion 150 in the axial direction of the case member 131 with respect to the first support portion 178 with the contact point with the support member 141 that abuts at the first support portion 178 as a fulcrum. At that time, the valve disk 161 compresses and deforms the contact portion 166A that abuts against the lid member 143 in the axial direction of the case member 131.

[0161] Due to the displacement as described above, the partition member 133A increases the volume of the first chamber 181. Here, when the partition member 133A is displaced, the volume of the second chamber 182 decreases. At that time, the hydraulic fluid L in the second chamber 182 flows into the lower chamber 20 via the passage portion 185.

[0162] Here, in the extension stroke, when the displacement of the partition member 133A is smaller than a predetermined amount, the valve closing portion 167A is separated from the valve seat member 142A, and thus the hydraulic fluid L flows from the entire second chamber 182 into the lower chamber 20 via the passage portion 185.

[0163] On the other hand, in the extending stroke, when the displacement of the partitioning member 133A is equal to or greater than a predetermined amount, the valve closing portion 167A abuts against the valve seat member 142A over the entire circumference, partitioning the second chamber 182 into a pressure chamber radially inside the valve closing portion 167A and a communication chamber radially outside the valve closing portion 167A. Although the communication chamber of the second chamber 182 communicates with the lower chamber 20 via the passage portion 185, the pressure chamber is in a state of not communicating with the lower chamber 20.

[0164] That is, the frequency-sensitive mechanism 130A displaces the partitioning member 133A by the hydraulic fluid L that has flowed into the first chamber 181 due to the movement of the piston 18 (see FIG. 2) in the extending stroke, and discharges at least a part of the hydraulic fluid L in the second chamber 182 that constitutes the second passage 191 to the lower chamber 20 in the cylinder 2 (see FIG. 2). Further, the frequency-sensitive mechanism 130A forms a pressure chamber in which the valve closing portion 167A is blocked between the lid member 143 and the valve seat member 142A in the second passage 191 and the partitioning member 133A, and restricts the movement of the hydraulic fluid L in the pressure chamber. The pressure chamber is formed when the partitioning member 133A is displaced and the valve closing portion 167A abuts against the valve seat member 142A in the second passage 191. The valve closing portion 167A is provided on the partitioning member 133A and is formed by an elastic member that abuts against the valve seat member 142A of the second passage 191 after the displacement of the partitioning member 133A and deforms so that the partitioning member 133A can still be displaced after the abutment. The frequency-sensitive mechanism 130A has the partitioning member 133A provided in the second passage 191. The partitioning member 133A partitions the second passage 191 between the first chamber 181 and the second chamber 182.

[0165] The shock absorber 1A varies the damping force in the same manner as the shock absorber 1 according to the piston frequency.

[0166] The shock absorber 1A of the second embodiment has a frequency-sensitive mechanism 130A provided in the second passage 191 for varying the damping force. The frequency-sensitive mechanism 130A forms a pressure chamber closed between a lid member 143 and a valve seat member 142A in the second passage 191 and a partition member 133A, and has a closing valve portion 167A for restricting the movement of the hydraulic fluid L in the pressure chamber. When the pressure in the first chamber 181 on the side opposite to the pressure chamber of the partition member 133A in the second passage 191 increases, the shock absorber 1A forms a pressure chamber closed between the inside of the second passage 191 and the partition member 133A, and accordingly, the pressure in the pressure chamber increases following this, suppressing the displacement of the partition member 133A. Thus, since the shock absorber 1A can suppress the displacement of the partition member 133A, the durability of the partition member 133A can be improved. Further, since the shock absorber 1A suppresses the displacement of the partition member 133A by the pressure of the hydraulic fluid L, generation of abnormal noise can be suppressed. Further, since the shock absorber 1A can gently suppress the displacement of the partition member 133A by the pressure of the hydraulic fluid L, a deterioration in the riding comfort caused by a rapid change in the damping force can be suppressed.

[0167] Further, in the shock absorber 1A, the pressure chamber is formed by contact between the valve seat member 142A and the closing valve portion 167A in the second passage 191 due to the displacement of the partition member 133A. The shock absorber 1A forms the pressure chamber in this way due to the displacement of the partition member 133A. Therefore, the shock absorber 1A can easily displace the partition member 133A without forming the pressure chamber due to the displacement of the partition member 133A to vary the damping force, or can form the pressure chamber to suppress the displacement of the partition member 133A.

[0168] Further, the closing valve portion 167A of the shock absorber 1A is provided on the partition member 133A, and is formed by an elastic member that contacts the valve seat member 142A of the second passage 191 after the displacement of the partition member 133A and deforms so that the partition member 133A can still be displaced after the contact. Therefore, the shock absorber 1A can easily form the pressure chamber due to the displacement of the partition member 133A, and can suppress the displacement of the partition member 133A more gently when suppressing the displacement of the partition member 133A.

[0169] [Third Embodiment] Next, the third embodiment will be mainly described focusing on the differences from the first embodiment with reference to FIG. 6. For the parts common to the first embodiment, the same names and the same reference numerals are used.

[0170] As shown in FIG. 6, the shock absorber 1B of the third embodiment has a frequency-sensitive mechanism 130B (second damping force mechanism) that is partially different from the frequency-sensitive mechanism 130 in place of the frequency-sensitive mechanism 130.

[0171] The frequency-sensitive mechanism 130B has a partition member 133B that is partially different from the partition member 133 in place of the partition member 133. The partition member 133B has an elastic seal member 162B that is partially different from the elastic seal member 162 in place of the elastic seal member 162. The elastic seal member 162B has a contact portion 166B that is partially different from the contact portion 166 in place of the contact portion 166, and the valve closing portion 167 is not provided.

[0172] The contact portion 166B has a base end portion 170B that is partially different from the base end portion 170 in place of the base end portion 170. The contact portion 166B is annular, and the base end portion 170B on the valve disk 161 side in the axial direction of the partition member 133B is fixed to the outer peripheral side of the valve disk 161 by baking.

[0173] The inner peripheral portion of the contact portion 166B has a larger inner diameter as it moves away from the valve disk 161 in the axial direction of the partition member 133B. The outer peripheral portion of the contact portion 166B has a smaller outer diameter as it moves away from the valve disk 161 in the axial direction of the partition member 133B. Therefore, the cross-sectional shape of the contact portion 166B in a plane including the central axis of the partition member 133B is a tapered mountain shape that becomes thinner as it moves away from the valve disk 161 in the axial direction of the partition member 133B.

[0174] The frequency sensing mechanism 130B has a valve case 145B that is partially different from the valve case 145, replacing the valve case 145. The valve case 145B has a valve seat member 142B that is partially different from the valve seat member 142, replacing the valve seat member 142. The valve seat member 142B has a valve closing portion 167B made of an elastic sealing material in addition to a plurality of (specifically, two) disks 136. The valve closing portion 167B is made of rubber and is annular. The valve closing portion 167B is coaxially arranged and adhered by baking to the outer peripheral edge of the disk 136 that is on the side of the support member 141 in the axial direction among the plurality of disks 136. The valve closing portion 167B protrudes from this disk 136 toward the support member 141 side in the axial direction of this disk 136.

[0175] The inner peripheral portion of the valve closing portion 167B has an inner diameter that increases as it moves away from the disk 136 in the axial direction of the valve seat member 142B. The outer peripheral portion of the valve closing portion 167B has an outer diameter that decreases as it moves away from the disk 136 in the axial direction of the valve seat member 142B. Therefore, the cross-sectional shape of the valve closing portion 167B in a plane including the central axis of the valve seat member 142B is a tapered, single mountain shape that becomes narrower as it moves away from the disk 136 in the axial direction of the valve seat member 142B. The cross-sectional shape of the valve closing portion 167B in a plane including the central axis of the valve seat member 142B is the same shape throughout the entire circumference.

[0176] The partitioning member 133B has a contact portion 166B that is arranged on the side opposite to the bottom portion 150 in the axial direction of the partitioning member 133B. The contact portion 166B contacts a lid member 143 composed of a plurality of disks 137 at the tip portion 171. The contact portion 166B biases the second support portion 179 side in the radial direction of the valve disk 161 toward the seat portion 154 side in the axial direction of the valve disk 161.

[0177] The valve closing portion 167B of the valve seat member 142B is located between the contact portion 166B and the support member 141 in the radial direction of the valve seat member 142B.

[0178] The partition member 133B is displaced relative to the valve seat member 142B due to the deformation of the valve disk 161 in the axial direction of the partition member 133B, whereby the valve disk 161 comes into and out of contact with the valve closing portion 167B. Note that the partition member 133B is not limited to being displaced in the axial direction by deformation, and may be displaced in the axial direction by movement.

[0179] The valve disk 161 of the partition member 133B can be bent in a tapered shape such that the second support portion 179 moves away from the seat portion 154 while maintaining the state where the first support portion 178 is in contact with the support member 141. When bending in this way, the valve disk 161 elastically deforms the contact portion 166B that contacts the lid member 143. Then, when bent by a predetermined amount, the valve disk 161 contacts the valve closing portion 167B of the valve seat member 142B.

[0180] The partition member 133B is provided in the valve case 145B and divides the inside of the valve case 145B into a first chamber 181 and a second chamber 182. The first chamber 181 is between the bottom portion 150 in the axial direction of the valve case 145B and the partition member 133B. The second chamber 182 is between the partition member 133B and the valve seat member 142B and the lid member 143 in the axial direction of the valve case 145B.

[0181] As shown in FIG. 6, in a state where the valve disk 161 of the partition member 133B is separated from the valve closing portion 167B of the valve seat member 142B, the entire second chamber 182 communicates with the lower chamber 20 through a passage portion 185 between the lid member 143 and the cylindrical portion 153 of the case member 131.

[0182] When the partition member 133B is deformed in a tapered shape and the valve disk 161 thereof is in contact with the valve closing portion 167B of the valve seat member 142B over the entire circumference, the second chamber 182 is partitioned into a pressure chamber radially inside the valve closing portion 167B and a communication chamber radially outside the valve closing portion 167B. This communication chamber communicates with the lower chamber 20 through the passage portion 185. This pressure chamber does not communicate with the communication chamber and thus does not communicate with the lower chamber 20 either.

[0183] In the extension stroke, the hydraulic fluid L from the upper chamber 19 (see FIG. 2) is introduced into the first chamber 181 through the first passage 43 (see FIG. 2), the passage in the notch 81 of the disk 50 (see FIG. 2), the passage in the groove portion 30 of the piston rod 21 shown in FIG. 6, and the passage in the passage groove 158 of the case member 131. Then, the valve disk 161 of the partition member 133B is tapered and bent so as to separate the second support portion 179 from the first support portion 178 in the axial direction of the case member 131 with the contact point with the support member 141 that abuts at the first support portion 178 as a fulcrum. At this time, the valve disk 161 compresses and deforms the contact portion 166B that abuts against the lid member 143 in the axial direction of the case member 131.

[0184] Due to the displacement of the partition member 133B as described above, the partition member 133B increases the volume of the first chamber 181. Here, when the partition member 133B is displaced, the volume of the second chamber 182 decreases. At this time, the hydraulic fluid L in the second chamber 182 flows into the lower chamber 20 through the passage portion 185.

[0185] Here, in the extension stroke, when the displacement of the partition member 133B is smaller than a predetermined amount, the valve disk 161 of the partition member 133B is separated from the valve closing portion 167B of the valve seat member 142B. Therefore, the hydraulic fluid L flows from the entire second chamber 182 into the lower chamber 20 through the passage portion 185.

[0186] On the other hand, in the extension stroke, when the displacement of the partition member 133B is equal to or greater than a predetermined amount, the valve disk 161 of the partition member 133B abuts against the valve closing portion 167B of the valve seat member 142B over the entire circumference, and the second chamber 182 is partitioned into a pressure chamber radially inside the valve closing portion 167B and a communication chamber radially outside the valve closing portion 167B. Although the communication chamber of the second chamber 182 communicates with the lower chamber 20 through the passage portion 185, the pressure chamber does not communicate with the lower chamber 20.

[0187] That is, in the frequency sensing mechanism 130B, the partitioning member 133B is displaced by the hydraulic fluid L that has flowed into the first chamber 181 due to the movement of the piston 18 (see FIG. 2) in the extending stroke, and at least a part of the hydraulic fluid L in the second chamber 182 that constitutes the second passage 191 is discharged into the lower chamber 20 in the cylinder 2 (see FIG. 2). Further, in the frequency sensing mechanism 130B, the valve closing portion 167B forms a pressure chamber blocked between the valve seat member 142B in the second passage 191 and the partitioning member 133B, and restricts the movement of the hydraulic fluid L in the pressure chamber. The pressure chamber is formed by the partitioning member 133B coming into contact with the valve closing portion 167B of the valve seat member 142B in the second passage 191 due to the displacement of the partitioning member 133B. The valve closing portion 167B is provided on the valve seat member 142B in the second passage 191, and is formed by an elastic member that comes into contact with the partitioning member 133B after the displacement of the partitioning member 133B and deforms so that the partitioning member 133B can still be displaced after the contact. The frequency sensing mechanism 130B has the partitioning member 133B provided in the second passage 191. The partitioning member 133B partitions the second passage 191 between the first chamber 181 and the second chamber 182.

[0188] The shock absorber 1B varies the damping force in the same manner as the shock absorber 1 according to the piston frequency.

[0189] The shock absorber 1B of the third embodiment is provided in the second passage 191, and a frequency-sensitive mechanism 130B that varies the damping force forms a pressure chamber blocked between a valve seat member 142B in the second passage 191 and a partition member 133B, and has a closing valve portion 167B that restricts the movement of the hydraulic fluid L in the pressure chamber. When the pressure in the first chamber 181 on the side opposite to the pressure chamber of the partition member 133B in the second passage 191 increases, the shock absorber 1B forms a pressure chamber blocked between the closing valve portion 167B in the second passage 191 and the partition member 133B, and accordingly, the pressure in the pressure chamber increases following this, suppressing the displacement of the partition member 133B. In this way, since the shock absorber 1B can suppress the displacement of the partition member 133B, the durability of the partition member 133B can be improved. Also, since the shock absorber 1B suppresses the displacement of the partition member 133B by the pressure of the hydraulic fluid L, the generation of abnormal noise can be suppressed. Further, since the shock absorber 1B can gently suppress the displacement of the partition member 133B by the pressure of the hydraulic fluid L, the deterioration of the riding comfort caused by a sudden change in the damping force can be suppressed.

[0190] Also, in the shock absorber 1B, the pressure chamber is formed by the partition member 133B coming into contact with the closing valve portion 167B in the second passage 191 due to the displacement of the partition member 133B. The shock absorber 1B forms the pressure chamber in this way due to the displacement of the partition member 133B. Therefore, the shock absorber 1B can easily displace the partition member 133B without forming the pressure chamber due to the displacement of the partition member 133B to vary the damping force, or can form the pressure chamber to suppress the displacement of the partition member 133B.

[0191] Also, in the shock absorber 1B, the closing valve portion 167B is provided on the valve seat member 142B which is a part of the second passage 191, comes into contact with the partition member 133B after the displacement of the partition member 133B, and is formed by an elastic member that deforms so that the partition member 133B can still be displaced after the contact. Therefore, when suppressing the displacement of the partition member 133B, the shock absorber 1B can suppress it more gently.

[0192] [Fourth Embodiment] Next, the fourth embodiment will be mainly described with reference to FIG. 7, focusing on the differences from the first embodiment. Regarding the parts common to the first embodiment, the same names and the same reference numerals are used.

[0193] As shown in FIG. 7, the shock absorber 1C of the fourth embodiment has a frequency-sensitive mechanism 130C (second damping force mechanism) that is partially different from the frequency-sensitive mechanism 130 in place of the frequency-sensitive mechanism 130.

[0194] The frequency-sensitive mechanism 130C has a partition member 133C that is partially different from the partition member 133 in place of the partition member 133. The partition member 133C has an elastic seal member 162C that is partially different from the elastic seal member 162 in place of the elastic seal member 162. The elastic seal member 162C is not provided with the contact portions 166 and 167.

[0195] The frequency-sensitive mechanism 130C has a valve case 145C that is partially different from the valve case 145 in place of the valve case 145. The valve case 145C has a support member 141C that is partially different from the support member 141 in place of the support member 141. The number of disks 135 of the support member 141C is different from that of the support member 141. The support member 141C is composed of a plurality of (specifically, seven) disks 135 having the same outer diameter and the same inner diameter. The valve case 145C is not provided with a plurality of disks 136 that constitute the valve seat member 142. Instead of these disks 136, the number of disks 135 that constitute the support member 141C is increased with respect to the support member 141. The support member 141C is thicker in the axial direction than the support member 141.

[0196] The valve case 145C has a lid member 143C that is partially different from the lid member 143 in place of the lid member 143. In addition to a plurality of (specifically, two) disks 137, the lid member 143C has a contact portion 166C and a valve closing portion 167C, both of which are made of an elastic sealing material. Both the contact portion 166C and the valve closing portion 167C are made of rubber and are both annular. The contact portion 166C and the valve closing portion 167C are both coaxially arranged on the outer peripheral side of the disk 137 at the end on the support member 141C side in the axial direction among the plurality of disks 137 and are adhered by baking. The contact portion 166C and the valve closing portion 167C both protrude from this disk 137 toward the support member 141C side in the axial direction of this disk 137.

[0197] The contact portion 166C is annular and protrudes from the disk 137 toward the bottom portion 150 side in the axial direction of the lid member 143C. The base end portion 170C of the contact portion 166C on the disk 137 side in the axial direction of the lid member 143C is fixed to the outer peripheral edge of the disk 137.

[0198] The outer peripheral portion of the contact portion 166C has a smaller outer diameter as it moves away from the disk 137 in the axial direction of the lid member 143C. The inner peripheral portion of the tip end portion 171C on the protruding side of the contact portion 166C has a larger inner diameter as it moves away from the disk 137 in the axial direction of the lid member 143C. Therefore, the tip end portion 171C of the contact portion 166C has a shape of a tapered single mountain shape that becomes thinner as it moves away from the disk 137 in the axial direction of the lid member 143C in the cross-sectional shape on the plane including the central axis of the lid member 143C.

[0199] The contact portion 166C is formed with a notch portion 172C at the tip end portion 171C that penetrates the tip end portion 171C in the radial direction of the lid member 143C. A plurality of notch portions 172C are formed in the contact portion 166C at intervals in the circumferential direction of the lid member 143C. Therefore, the tip end portion 171C of the contact portion 166C is intermittently notched in the circumferential direction of the lid member 143C.

[0200] The valve closing part 167C is annular and protrudes from the disk 137 toward the bottom part 150 in the axial direction of the lid member 143C. The valve closing part 167C is provided on the inner circumferential side of the contact part 166C in the radial direction of the lid member 143C. The base end part 174C of the valve closing part 167C on the disk 137 side in the axial direction of the lid member 143C is fixed by baking to the inner circumferential side of the contact part 166C of the disk 137. The valve closing part 167C has this base end part 174C connected to the base end part 170C of the contact part 166C and integrated therewith.

[0201] The inner circumferential part of the valve closing part 167C has an inner diameter that increases as it moves away from the disk 137 in the axial direction of the lid member 143C. The outer circumferential part of the tip end part 175C on the protruding side of the valve closing part 167C has an outer diameter that decreases as it moves away from the disk 137 in the axial direction of the lid member 143C. Therefore, the valve closing part 167C has a shape of a single tapered mountain shape where the cross-sectional shape in a plane including the central axis of the lid member 143C becomes thinner as it moves away from the disk 137 in the axial direction of the lid member 143C. Therefore, the lid member 143C has a shape of two mountain shapes formed by the tip end part 171C of the contact part 166C and the tip end part 175C of the valve closing part 167C. The cross-sectional shape of the tip end part 175C of the valve closing part 167C in a plane including the central axis of the lid member 143C is the same shape over the entire circumference. The protruding height of the valve closing part 167C from the disk 137 is lower than the protruding height of the contact part 166C from the disk 137.

[0202] Between the valve closing part 167C and the contact part 166C in the radial direction of the lid member 143C, there is a concave part 176C. The concave part 176C is recessed toward the disk 137 side from the tip end part 171C of the contact part 166C and the tip end part 175C of the valve closing part 167C in the axial direction of the lid member 143C. The concave part 176C is an annular shape that is continuous over the entire circumference of the lid member 143C.

[0203] The lid member 143C has an abutting portion 166C and a valve closing portion 167C disposed on the bottom 150 side in the axial direction of the lid member 143C. The abutting portion 166C abuts on the valve disk 161 of the partitioning member 133C at the tip portion 171C. The abutting portion 166C biases the second support portion 179 side in the radial direction of the valve disk 161 toward the seat portion 154 side in the axial direction of the valve disk 161.

[0204] The valve closing portion 167C of the lid member 143C is on the support member 141C side in the axial direction of the lid member 143C. The valve closing portion 167C of the lid member 143C is between the abutting portion 166C and the support member 141C in the radial direction of the lid member 143C.

[0205] In the axial direction of the partitioning member 133C, the valve disk 161 is displaced relative to the lid member 143C due to the deformation of the valve disk 161, whereby the valve disk 161 is disengaged from and seated on the valve closing portion 167C. Note that the partitioning member 133C is not limited to being displaced in the axial direction by deforming, and may be displaced in the axial direction by moving.

[0206] The valve disk 161 of the partitioning member 133C can be bent in a tapered shape such that the second support portion 179 moves away from the seat portion 154 while maintaining the state where the first support portion 178 abuts on the support member 141C. When bending in this way, the valve disk 161 elastically deforms the abutting portion 166C of the lid member 143C that abuts on the valve disk 161. Then, when bent by a predetermined amount, the valve disk 161 abuts on the valve closing portion 167C of the lid member 143C.

[0207] The partitioning member 133C is provided in the valve case 145C and partitions the inside of the valve case 145C into a first chamber 181 and a second chamber 182. The first chamber 181 is between the bottom 150 in the axial direction of the valve case 145C and the partitioning member 133C. The second chamber 182 is between the partitioning member 133C and the lid member 143C in the axial direction of the valve case 145C.

[0208] As shown in Fig. 7, when the valve disk 161 of the partition member 133C is separated from the valve closing portion 167C of the lid member 143C, the entire second chamber 182 communicates with the lower chamber 20 through a passage portion 185 between the lid member 143C and the cylindrical portion 153 of the case member 131.

[0209] When the partition member 133C is deformed into a tapered shape and its valve disk 161 is in contact with the valve closing portion 167C of the lid member 143C over the entire circumference, the second chamber 182 is partitioned into a pressure chamber radially inside the valve closing portion 167C and a communication chamber radially outside the valve closing portion 167C. This communication chamber communicates with the lower chamber 20 through the passage portion 185. This pressure chamber does not communicate with the communication chamber and thus does not communicate with the lower chamber 20 either.

[0210] In the extension stroke, the hydraulic fluid L from the upper chamber 19 (see Fig. 2) is introduced into the first chamber 181 through the first passage 43 (see Fig. 2), the passage in the notch 81 (see Fig. 2) of the disk 50 (see Fig. 2), the passage in the groove portion 30 of the piston rod 21 shown in Fig. 7, and the passage in the passage groove 158 of the case member 131. Then, the valve disk 161 of the partition member 133C bends in a tapered shape so as to separate the second support portion 179 from the bottom portion 150 in the axial direction of the case member 131 with respect to the first support portion 178 with the contact point with the support member 141C that abuts at the first support portion 178 as a fulcrum. At that time, the valve disk 161 compresses and deforms the contact portion 166C of the lid member 143C that abuts against the valve disk 161 in the axial direction of the case member 131.

[0211] Due to the displacement as described above, the partition member 133C increases the volume of the first chamber 181. Here, when the partition member 133C is displaced, the volume of the second chamber 182 decreases. At that time, the hydraulic fluid L in the second chamber 182 flows into the lower chamber 20 through the passage portion 185.

[0212] Here, in the extension stroke, when the displacement of the partitioning member 133C is smaller than a predetermined amount, the valve disk 161 is separated from the valve closing portion 167C of the lid member 143C. Therefore, the hydraulic fluid L flows from the entire second chamber 182 to the lower chamber 20 through the passage portion 185.

[0213] On the other hand, in the extension stroke, when the displacement of the partitioning member 133C is equal to or greater than a predetermined amount, the valve disk 161 abuts against the valve closing portion 167C of the lid member 143C over the entire circumference, and the second chamber 182 is partitioned into a pressure chamber radially inside the valve closing portion 167C and a communication chamber radially outside the valve closing portion 167C. Although the communication chamber of the second chamber 182 communicates with the lower chamber 20 through the passage portion 185, the pressure chamber is in a state of not communicating with the lower chamber 20.

[0214] That is, the frequency sensing mechanism 130C causes the partitioning member 133C to be displaced by the hydraulic fluid L that has flowed into the first chamber 181 due to the movement of the piston 18 (see FIG. 2) in the extension stroke, and discharges at least a part of the hydraulic fluid L in the second chamber 182 that constitutes the second passage 191 to the lower chamber 20 in the cylinder 2 (see FIG. 2). Further, the frequency sensing mechanism 130C forms a pressure chamber in which the valve closing portion 167C is blocked between the lid member 143C and the partitioning member 133C in the second passage 191, and restricts the movement of the hydraulic fluid L in the pressure chamber. The pressure chamber is formed by the partitioning member 133C coming into contact with the valve closing portion 167C of the lid member 143C in the second passage 191 due to the displacement of the partitioning member 133C. The valve closing portion 167C is provided in the second passage 191 and is formed by an elastic member that comes into contact with the partitioning member 133C after the displacement of the partitioning member 133C and deforms so that the partitioning member 133C can still be displaced after the contact. The frequency sensing mechanism 130C has the partitioning member 133C provided in the second passage 191. The partitioning member 133C partitions the second passage 191 between the first chamber 181 and the second chamber 182.

[0215] The shock absorber 1C varies the damping force in the same manner as the shock absorber 1 according to the piston frequency.

[0216] The shock absorber 1C of the fourth embodiment has a frequency-sensitive mechanism 130C provided in the second passage 191 for varying the damping force, which forms a pressure chamber blocked between a lid member 143C in the second passage 191 and a partitioning member 133C, and has a closing valve portion 167C for restricting the movement of the hydraulic fluid L in the pressure chamber. When the pressure in the first chamber 181 on the side opposite to the pressure chamber of the partitioning member 133C in the second passage 191 increases, the shock absorber 1C forms a pressure chamber blocked between the closing valve portion 167C in the second passage 191 and the partitioning member 133C, and accordingly, the pressure in the pressure chamber increases following this, suppressing the displacement of the partitioning member 133C. Thus, since the shock absorber 1C can suppress the displacement of the partitioning member 133C, the durability of the partitioning member 133C can be improved. Also, since the shock absorber 1C suppresses the displacement of the partitioning member 133C by the pressure of the hydraulic fluid L, the generation of abnormal noise can be suppressed. Further, since the shock absorber 1C can gently suppress the displacement of the partitioning member 133C by the pressure of the hydraulic fluid L, the deterioration of the riding comfort caused by a sudden change in the damping force can be suppressed.

[0217] Also, the pressure chamber of the shock absorber 1C is formed by the partitioning member 133C coming into contact with the closing valve portion 167C in the second passage 191 due to the displacement of the partitioning member 133C. The shock absorber 1C forms the pressure chamber in this way due to the displacement of the partitioning member 133C. Therefore, the shock absorber 1C can easily displace the partitioning member 133C without forming a pressure chamber due to the displacement of the partitioning member 133C to vary the damping force, or can form a pressure chamber to suppress the displacement of the partitioning member 133C.

[0218] Also, the closing valve portion 167C of the shock absorber 1C is provided on a lid member 143C which is a part of the second passage 191, comes into contact with the partitioning member 133C after the displacement of the partitioning member 133C, and is formed by an elastic member that deforms so that the partitioning member 133C can still be displaced after the contact. Therefore, the shock absorber 1C can suppress the displacement of the partitioning member 133C even more gently when suppressing the displacement of the partitioning member 133C.

[0219] [Fifth Embodiment] Next, the fifth embodiment will be mainly described with reference to FIG. 8, focusing on the differences from the first embodiment. For the parts common to the first embodiment, the same names and the same reference numerals are used.

[0220] As shown in FIG. 8, the shock absorber 1D of the fifth embodiment has a frequency-sensitive mechanism 130D (second damping force mechanism) that is partially different from the frequency-sensitive mechanism 130, instead of the frequency-sensitive mechanism 130.

[0221] The frequency-sensitive mechanism 130D has a partition member 133D that is partially different from the partition member 133, instead of the partition member 133. The partition member 133D has an elastic seal member 162D that is partially different from the elastic seal member 162, instead of the elastic seal member 162. The elastic seal member 162D has a contact portion 166D that is partially different from the contact portion 166, instead of the contact portion 166. The elastic seal member 162D has a valve closing portion 167D that is partially different from the valve closing portion 167, instead of the valve closing portion 167.

[0222] The contact portion 166D has a base end portion 170D that is partially different from the base end portion 170, instead of the base end portion 170. The contact portion 166D is annular, and the base end portion 170D on the valve disk 161 side in the axial direction of the partition member 133D is fixed to the outer peripheral side of the valve disk 161 by baking.

[0223] The inner peripheral portion of the contact portion 166D has a larger inner diameter as it moves away from the valve disk 161 in the axial direction of the partition member 133D. The outer peripheral portion of the contact portion 166D has a smaller outer diameter as it moves away from the valve disk 161 in the axial direction of the partition member 133D. Therefore, the cross-sectional shape of the contact portion 166D in a plane including the central axis of the partition member 133D is a tapered mountain shape that becomes thinner as it moves away from the valve disk 161 in the axial direction of the partition member 133D.

[0224] The valve closing portion 167D is provided at a distance from the contact portion 166D in the radial direction of the partitioning member 133D. The valve closing portion 167D is fixed to the valve disk 161 by baking. In the axial direction of the partitioning member 133D, the base end portion 174D of the valve closing portion 167D on the valve disk 161 side has an outer diameter that increases and an inner diameter that also increases as it moves away from the valve disk 161 in the axial direction of the partitioning member 133D. In the axial direction of the partitioning member 133D, the tip end portion 175D of the valve closing portion 167D on the side opposite to the valve disk 161 has an outer diameter that decreases and an inner diameter that also decreases as it moves away from the valve disk 161 in the axial direction of the partitioning member 133D. The cross-sectional shape of the valve closing portion 167D in a plane including the central axis of the partitioning member 133D is the same shape throughout the entire circumference.

[0225] The frequency sensing mechanism 130D has a valve case 145D that is partly different from the valve case 145 instead of the valve case 145. The valve case 145D has a support member 141D that is partly different from the support member 141 instead of the support member 141. The support member 141D is composed of a plurality of (specifically, five) disks 135 having the same outer diameter and the same inner diameter. The valve case 145D is not provided with a plurality of disks 136 that constitute the valve seat member 142. Instead of these disks 136, among the disks 135 that constitute the support member 141D, the thickness of the disk 135 on the side most opposite to the disk 132 in the axial direction of the support member 141D is increased. The support member 141D is thicker in the axial direction than the support member 141.

[0226] The valve case 145D is provided with a single lid member 143D instead of the lid member 143 and the annular member 138. The lid member 143D has a main body portion 231 and a protruding portion 232. The lid member 143D is made of metal, and the main body portion 231 and the protruding portion 232 are integrally formed seamlessly by sintering or the like.

[0227] The main body part 231 is a perforated disk shape, with a constant outer diameter over the entire circumference and a constant radial width over the entire circumference. The main body part 231 has an axial thickness equivalent to that of the annular member 138. The valve case 145D has the main body part 231 fitted to the mounting shaft part 28 of the piston rod 21.

[0228] The protruding part 232 has an outer peripheral part that is tapered coaxially with the main body part 231 and has a smaller diameter as it moves away from the main body part 231 in the axial direction. The protruding part 232 has an inner peripheral part that is tapered coaxially with the main body part 231 and has a larger diameter as it moves away from the main body part 231 in the axial direction. The protruding part 232 has a cross-sectional shape in a plane including the central axis of the lid member 143D that is the same over the entire circumference.

[0229] In the partition member 133D, the contact part 166D and the valve closing part 167D are arranged on the side opposite to the bottom part 150 in the axial direction of the partition member 133D. The contact part 166D contacts the main body part 231 of the lid member 143D at the tip part 171. The contact part 166D biases the second support part 179 side in the radial direction of the valve disk 161D toward the sheet part 154 side in the axial direction of the valve disk 161.

[0230] The protruding part 232 of the lid member 143D is on the support member 141D side in the axial direction of the lid member 143D. The protruding part 232 of the lid member 143D is between the contact part 166D and the valve closing part 167D in the radial direction of the lid member 143D. The maximum outer diameter of the valve closing part 167D is equivalent to the maximum inner diameter of the protruding part 232.

[0231] In the partition member 133D, when the valve disk 161 deforms in the axial direction of the partition member 133D, the valve closing part 167D is displaced relative to the lid member 143D, and as a result, the valve disk 161 separates from and seats on the protruding part 232 of the lid member 143D. Note that the partition member 133D is not limited to being displaced in the axial direction by deforming, and may be displaced in the axial direction by moving.

[0232] The valve disk 161 of the partition member 133D can be bent in a tapered shape so that the second support portion 179 moves away from the sheet portion 154 while maintaining the state where the first support portion 178 abuts against the support member 141. When bending in this way, the valve disk 161 elastically deforms the contact portion 166D that contacts the main body portion 231 of the lid member 143D. Then, when bent by a predetermined amount, the valve disk 161 has the closing valve portion 167D abut against and fit into the inner peripheral portion of the protruding portion 232 of the lid member 143.

[0233] The partition member 133D is provided in the valve case 145D and partitions the inside of the valve case 145D into a first chamber 181 and a second chamber 182. The first chamber 181 is located between the bottom portion 150 in the axial direction of the valve case 145D and the partition member 133D. The second chamber 182 is located between the partition member 133D and the lid member 143D in the axial direction of the valve case 145D.

[0234] As shown in FIG. 8, in a state where the closing valve portion 167D of the partition member 133D is separated from the protruding portion 232 of the lid member 143D, the entire second chamber 182 communicates with the lower chamber 20 through a passage portion 185 between the main body portion 231 of the lid member 143D and the cylindrical portion 153 of the case member 131.

[0235] In a state where the closing valve portion 167D of the partition member 133D abuts against and fits into the protruding portion 232 of the lid member 143D, the second chamber 182 is partitioned into a pressure chamber radially inside the closing valve portion 167D and a communication chamber radially outside the closing valve portion 167D. This communication chamber communicates with the lower chamber 20 through the passage portion 185. This pressure chamber does not communicate with the communication chamber and thus does not communicate with the lower chamber 20 either.

[0236] In the extending stroke, the hydraulic fluid L from the upper chamber 19 (see FIG. 2) is introduced into the first chamber 181 through the first passage 43 (see FIG. 2), the passage in the notch 81 (see FIG. 2) of the disk 50 (see FIG. 2), the passage in the groove portion 30 of the piston rod 21 shown in FIG. 8, and the passage in the passage groove 158 of the case member 131. Then, the valve disk 161 of the partition member 133D is bent in a tapered shape so as to separate the second support portion 179 from the bottom portion 150 in the axial direction of the case member 131 with respect to the first support portion 178 with the contact point with the support member 141 that abuts on the first support portion 178 as a fulcrum. At this time, the valve disk 161 compresses and deforms the contact portion 166D that abuts on the lid member 143D in the axial direction of the case member 131.

[0237] Due to the displacement as described above, the partition member 133D increases the volume of the first chamber 181. Here, when the partition member 133D is displaced, the volume of the second chamber 182 decreases. At this time, the hydraulic fluid L in the second chamber 182 flows into the lower chamber 20 through the passage portion 185.

[0238] Here, in the extending stroke, when the displacement of the partition member 133D is smaller than a predetermined amount, the closing valve portion 167D is separated from the protruding portion 232 of the lid member 143D. Therefore, the hydraulic fluid L flows from the entire second chamber 182 into the lower chamber 20 through the passage portion 185.

[0239] On the other hand, in the extending stroke, when the displacement of the partition member 133D is equal to or greater than a predetermined amount, the closing valve portion 167D abuts on and fits with the protruding portion 232 of the lid member 143D, and the second chamber 182 is partitioned into a pressure chamber radially inside the closing valve portion 167D and a communication chamber radially outside the closing valve portion 167D. Although the communication chamber of the second chamber 182 communicates with the lower chamber 20 through the passage portion 185, the pressure chamber does not communicate with the lower chamber 20.

[0240] That is, in the frequency-sensitive mechanism 130D, the partitioning member 133D is displaced by the hydraulic fluid L that has flowed into the first chamber 181 due to the movement of the piston 18 (see FIG. 2) during the extension stroke, and at least a part of the hydraulic fluid L in the second chamber 182 that constitutes the second passage 191 is discharged into the lower chamber 20 in the cylinder 2 (see FIG. 2). Further, in the frequency-sensitive mechanism 130D, the valve closing portion 167D forms a pressure chamber that is blocked between the lid member 143D in the second passage 191 and the partitioning member 133D, and restricts the movement of the hydraulic fluid L in the pressure chamber. The pressure chamber is formed when the partitioning member 133D is displaced and the valve closing portion 167D of the partitioning member 133D comes into contact with and fits with the protruding portion 232 of the lid member 143D in the second passage 191. The valve closing portion 167D is provided on the partitioning member 133D and is formed by an elastic member that deforms so as to come into contact with and fit with the protruding portion 232 after the displacement of the partitioning member 133D and allows the partitioning member 133D to be displaceable even after the contact. The frequency-sensitive mechanism 130D has the partitioning member 133D provided in the second passage 191. The partitioning member 133D partitions the second passage 191 between the first chamber 181 and the second chamber 182.

[0241] The shock absorber 1D varies the damping force in the same manner as the shock absorber 1 according to the piston frequency.

[0242] The shock absorber 1D of the fifth embodiment has a frequency-sensitive mechanism 130D provided in the second passage 191 for varying the damping force, which forms a pressure chamber blocked between a lid member 143D in the second passage 191 and a partition member 133D, and has a closed valve portion 167D for restricting the movement of the hydraulic fluid L in the pressure chamber. When the pressure in the first chamber 181 on the side opposite to the pressure chamber of the partition member 133D in the second passage 191 increases, the shock absorber 1D forms a pressure chamber blocked between the closed valve portion 167D and the partition member 133D in the second passage 191, and accordingly, the pressure in the pressure chamber increases following this, suppressing the displacement of the partition member 133D. Thus, since the shock absorber 1D can suppress the displacement of the partition member 133D, the durability of the partition member 133D can be improved. Also, since the shock absorber 1D suppresses the displacement of the partition member 133D by the pressure of the hydraulic fluid L, the generation of abnormal noise can be suppressed. Further, since the shock absorber 1D can gently suppress the displacement of the partition member 133D by the pressure of the hydraulic fluid L, the deterioration of the riding comfort caused by a sudden change in the damping force can be suppressed.

[0243] Also, in the shock absorber 1D, the pressure chamber is formed by the contact between the closed valve portion 167D provided on the partition member 133D and the lid member 143D in the second passage 191 due to the displacement of the partition member 133D. Thus, the shock absorber 1D forms the pressure chamber due to the displacement of the partition member 133D. Therefore, the shock absorber 1D can easily displace the partition member 133D without forming a pressure chamber due to the displacement of the partition member 133D to vary the damping force, or can form a pressure chamber to suppress the displacement of the partition member 133D.

[0244] Also, the closed valve portion 167D of the shock absorber 1D is formed by an elastic member provided on the partition member 133D, which contacts the lid member 142D of the second passage 191 after the displacement of the partition member 133D and deforms so that the partition member 133D can still be displaced after the contact. Therefore, the shock absorber 1D can easily form a pressure chamber due to the displacement of the partition member 133D, and can suppress the displacement of the partition member 133D more gently when suppressing the displacement of the partition member 133D.

[0245] [Sixth Embodiment] Next, the differences between the sixth embodiment and the first embodiment will be mainly described with reference to FIG. 9, centering on the parts that are different. For the parts common to the first embodiment, the same names and the same reference numerals are used.

[0246] As shown in FIG. 9, the shock absorber 1E of the sixth embodiment has a piston rod 21E that is partially different from the piston rod 21. The piston rod 21E has a spindle portion 313A and a mounting shaft portion 313B whose outer diameter is smaller than the outer diameter of the spindle portion 313A.

[0247] The insertion end of the piston rod 21E into the inner cylinder 3 of the cylinder 2 is the mounting shaft portion 313B. The boundary between the spindle portion 313A and the mounting shaft portion 313B of the piston rod 21E is a stepped shaft step portion 313C. The side of the piston rod 21E opposite to the mounting shaft portion 313B in the axial direction of the spindle portion 313A is inserted through the rod guide 22 (see FIG. 1) and the seal member 23 (see FIG. 1) and extends outside the cylinder 2.

[0248] The shock absorber 1E includes a piston valve device 320. The piston valve device 320 has stopper pieces 322, 323, a piston 18E, and a valve stopper 325 that are all fitted on the outer periphery of the mounting shaft portion 313B of the piston rod 21E. These stopper pieces 322, 323, the piston 18E, and the valve stopper 325 are clamped and fixed between the stepped shaft portion 313C of the piston rod 21E by a valve housing 361 screwed to the screw portion 321 at the tip of the mounting shaft portion 313B. These stopper pieces 322, 323, the piston 18E, and the valve stopper 325 are connected to the mounting shaft portion 313B of the piston rod 21E. The valve housing 361 is a component for the sub-extension side damping valve 360. Note that the stopper piece 322 is provided with a flow path 322A that communicates with a bypass passage 351 (described later) of the piston rod 21E and opens into the upper chamber 19 inside the inner cylinder 3.

[0249] Piston 18E is slidably fitted into the inner cylinder 3. The piston 18E is provided with a first passage 43E on the extending side and a first passage 44E on the contracting side. The first passage 43E and the first passage 44E communicate with each other such that the hydraulic fluid L can flow between the upper chamber 19 and the lower chamber 20 as the piston 18E moves. The piston 18E clamps the annular central portion of the disk valve-shaped main extending-side damping valve 333 between it and the valve stopper 325. The portion where the main extending-side damping valve 333 of the piston 18E separates from and seats on the piston 18E and the main extending-side damping valve 333 constitute a damping force mechanism 41E (first damping force mechanism) that opens and closes the first passage 43E.

[0250] The piston 18E clamps the annular central portion of the disk valve-shaped pressure-side damping valve 334 between it and the stopper piece 323. The portion where the pressure-side damping valve 334 of the piston 18E separates from and seats on the piston 18E and the pressure-side damping valve 334 constitute a damping force mechanism 42E (first damping force mechanism) that opens and closes the first passage 44E. The piston valve device 320 divides the inside of the inner cylinder 3 into an upper chamber 19 and a lower chamber 20 by the piston 18E. Further, the piston valve device 320 communicates the upper chamber 19 and the lower chamber 20 via the main extending-side damping valve 333 that opens and closes the first passage 43E and the first passage 43E provided in the piston 18E. Further, the piston valve device 320 communicates the lower chamber 20 and the upper chamber 19 via the pressure-side damping valve 334 that opens and closes the first passage 44E and the first passage 44E.

[0251] Therefore, in the extension stroke of the shock absorber 1E, the hydraulic fluid L in the upper chamber 19 passes through the first passage 43E of the piston 18E, deflects and deforms the main extending-side damping valve 333 provided in the first passage 43E to open it, and is led to the lower chamber 20. At that time, the main extending-side damping valve 333 generates an extending-side damping force. Also, in the contraction stroke, the hydraulic fluid L in the lower chamber 20 passes through the first passage 44E of the piston 18E, deflects and deforms the pressure-side damping valve 334 to open it, and is led to the upper chamber 19. At that time, the pressure-side damping valve 334 generates a pressure-side damping force.

[0252] The shock absorber 1E is provided with an extension damping force adjustment mechanism 350 (second damping force mechanism) for varying and adjusting the damping force of the piston valve device 320, specifically the extension damping force in this embodiment, as follows.

[0253] The extension damping force adjustment mechanism 350 is provided on the outer surface of the piston rod 21E with a bypass passage 351 that bypasses the main extension damping valve 333 and extends to communicate the upper chamber 19 and the lower chamber 20.

[0254] The extension damping force adjustment mechanism 350 is provided with a sub-extension damping valve 360 in this bypass passage 351. A valve stopper 325 is inserted into the mounting shaft portion 313B of the piston rod 21E. The main body 361A of the valve housing 361 is screwed onto the threaded portion 321 of the mounting shaft portion 313B of the piston rod 21E. The annular central portion of the disk valve-shaped sub-extension damping valve 360 is clamped between the lower end central annular protrusion of the valve stopper 325 and the upper end central annular protrusion of the main body 361A. One end of the bypass passage 351 of the extension damping force adjustment mechanism 350 opens into the upper chamber 19, and the other end of the bypass passage 351 opens into a sub-flow path 325A provided in the valve stopper 325. The extension damping force adjustment mechanism 350 opens and closes this sub-flow path 325A with respect to the lower chamber 20 by means of the sub-extension damping valve 360.

[0255] The extension-side damping force adjustment mechanism 350 attaches the sub-extension-side damping valve 360 to the valve stopper 325 and makes it contact and separate from the piston round 325B of the valve stopper 325. Then, the extension-side damping force adjustment mechanism 350 provides a back pressure chamber 363 on the back side of the sub-extension-side damping valve 360, which communicates with the upper chamber 19 through the orifice 362A of the slit valve 362. The extension-side damping force adjustment mechanism 350 closes the back pressure chamber 363 with a partitioning member 133E having one or more laminated leaf springs 371. The slit valve 362 is attached to the back of the sub-extension-side damping valve 360. The slit valve 362 has its annular central portion clamped between the central annular protrusion at the lower end of the valve stopper 325 and the central annular protrusion at the upper end of the main body 361A of the valve housing 361. The slit valve 362 has a slit formed on its inner circumference to constitute the orifice 362A.

[0256] The extension-side damping force adjustment mechanism 350 has a main body 361A of the valve housing 361 screwed onto the threaded portion 321 of the mounting shaft portion 313B of the piston rod 21E. The extension-side damping force adjustment mechanism 350 has the main body 361A having a disk portion a screwed onto the threaded portion 321 and an annular portion b protruding from the lower part on the outer peripheral side of the disk portion a. The extension-side damping force adjustment mechanism 350 has an end cap 365 screwed onto the inner circumference of the annular portion b of the main body 361A. The valve housing 361 is provided with a plurality of communication holes 361B at a plurality of circumferential positions of the disk portion a of the main body 361A. The plurality of communication holes 361B of the valve housing 361 enable communication with the back pressure chamber 363 on both axial sides of the valve housing 361 inside the valve housing 361.

[0257] The back pressure chamber 363 is partitioned from the lower chamber 20 by the valve housing 361, a backup collar 367, and a partitioning member 133E. The backup collar 367 is slidably provided on the outer circumference of the disk portion a of the main body 361A of the valve housing 361. The backup collar 367 is urged by a spring 366 to abut against the back of the sub-extension-side damping valve 360. The partitioning member 133E is supported so as to be able to contact and separate from a valve seat 368A, which is the upper end portion on the back pressure chamber 363 side of the end cap 365.

[0258] A sealing material 361C is attached to an annular groove on the outer periphery of the disk portion a of the main body 361A of the valve housing 361. The backup collar 367 slides up and down in a liquid-tight state with respect to the sealing material 361C. The upper end surface of the backup collar 367 abuts against the back surface of the sub-extension-side damping valve 360. The spring 366 has a cross-shaped overhanging portion 366A on the outer periphery of the annular central portion. The spring 366 is seated and supported on the upper surface around the upper-end central annular protrusion of the main body 361A of the valve housing 361. The spring 366 supports the backup collar 367 on the tip of the overhanging portion 366A.

[0259] The extension-side damping force adjustment mechanism 350 is provided, on the back side of the sub-extension-side damping valve 360, with a valve housing 361 attached to the piston rod 21E, a backup collar 367, and a back-pressure chamber 363. The backup collar 367 is slidably provided on the outer periphery of the valve housing 361 and pressed against the back surface of the sub-extension-side damping valve 360. The back-pressure chamber 363 is partitioned from the lower chamber 20 by a partitioning member 133E. Then, the extension-side damping force adjustment mechanism 350 biases and presses the upper end surface of the backup collar 367 against the back surface of the sub-extension-side damping valve 360 by a spring 366 seated and supported on the upper surface of the disk portion a of the main body 361A of the valve housing 361 inside the back-pressure chamber 363.

[0260] The partition member 133E has a disk-shaped leaf spring 371 without holes. The partition member 133E has a support spring 372, and the supported portion 371A on the outer periphery of the leaf spring 371 is seated and supported on the valve seat 368A of the end cap 365 by the support spring 372. The support spring 372 is a thin annular spring. The support spring 372 has a plurality of upward spring legs 372B and a plurality of downward spring legs 372C at regular intervals on the outer periphery of the plate-shaped annular portion 372A. The spring leg 372B extends obliquely upward from the outer peripheral portion of the annular portion 372A. The spring leg 372C extends obliquely downward from the outer peripheral portion of the annular portion 372A. The spring leg 372B and the spring leg 372C are alternately provided on the outer periphery of the annular portion 372A in the circumferential direction of the annular portion 372A. The support spring 372 has the upward spring leg 372B abutting against the spring contact surface 369A which is the lower end surface of the disk portion a of the main body 361A of the valve housing 361. The support spring 372 has the downward spring leg 372C abutting against the leaf spring 371. Thus, the support spring 372 presses the supported portion 371A of the leaf spring 371 against the valve seat 368A of the end cap 365 to seat it.

[0261] The outer periphery of the leaf spring 371 of the partition member 133E is not fixedly held on the valve seat 368A of the end cap 365. The outer periphery of the leaf spring 371 slides along the surface of the valve seat 368A and is free to move. The spring constant of the leaf spring 371 is set low. The support spring 372 of the partition member 133E also slides along the spring contact surface 369A of the valve housing 361 and is free to move.

[0262] A concave surface 368B that restricts the deflection of the leaf spring 371 of the partition member 133E is provided on the end cap 365. The concave surface 368B restricts the amount of elastic deflection of the elastic deflection portion 371B radially inside the supported portion 371A of the leaf spring 371 that is pushed in by the pressure in the back pressure chamber 363 and bends in a curved shape. The concave surface 368B is provided on the inner peripheral side surrounded by the valve seat 368A in the end cap 365 so as to form a certain step with respect to the valve seat 368A. The concave surface 368B is composed of a tapered downward slope surface 368C provided at the boundary portion with the valve seat 368A and a flat surface 368D continuous with the inner peripheral side of the downward slope surface 368C. The concave surface 368B forms a step corresponding to the depth of the flat surface 368D with respect to the valve seat 368A. The valve seat 368A and the concave surface 368B are circular. The downward slope surface 368C forms a conical tapered surface.

[0263] The partition member 133E has the leaf spring 371 partitioning the above-described back pressure chamber 363 and the chamber 402. The chamber 402 communicates with the lower chamber 20 through a communication hole 403 provided in the end cap 365. The communication hole 403 has a large-diameter hole 380 that opens into the lower chamber 20, an intermediate hole 381 smaller in diameter than the large-diameter hole 380, and a small-diameter hole 382 smaller in diameter than the intermediate hole 381 and opening at the radial center of the flat surface 368D of the concave surface 368B. The flow path 322A, the bypass passage 351, the orifice 362A, the back pressure chamber 363, the chamber 402, and the communication hole 403 constitute the second passage 191E. The second passage 191E is provided in parallel with the first passage 43E and the first passage 44E. The second passage 191E is provided such that the oil fluid L in the upper chamber 19 can flow in due to the movement of the piston 18E in the extension stroke. The second passage 191E is provided such that the oil fluid L in the lower chamber 20 can flow in due to the movement of the piston 18E in the compression stroke.

[0264] In the partition member 133E, a valve closing portion 167E made of an elastic sealing material is provided on the chamber 402 side of the leaf spring 371. The valve closing portion 167E is made of rubber and has a disc shape. The valve closing portion 167E is adhered to the central position in the radial direction of the leaf spring 371. The valve closing portion 167E is baked onto the metal leaf spring 371 and provided integrally with the leaf spring 371. The valve closing portion 167E has an annular closing portion 408 that protrudes axially from the inner side at the outer peripheral edge portion. The cross-sectional shape of the valve closing portion 167E in the plane including its central axis is the same shape throughout the entire circumference.

[0265] As shown in FIG. 9, when the valve closing portion 167E of the partition member 133E is separated from the end cap 365, the entire chamber 402 communicates with the lower chamber 20 through the communication hole 403 of the end cap 365.

[0266] When the leaf spring 371 of the partition member 133E deflects toward the flat surface 368D side of the end cap 365, the valve closing portion 167E abuts against the flat surface 368D over the entire circumference such that the closing portion 408 surrounds the small-diameter hole 382 of the communication hole 403. Then, the valve closing portion 167E closes the communication hole 403. In this state, the chamber 402 forms a pressure chamber closed on the outside in the radial direction from the valve closing portion 167E. This pressure chamber does not communicate with the lower chamber 20.

[0267] In the extension stroke, the leaf spring 371 of the partition member 133E receives the pressure of the back pressure chamber 363 to which the pressure of the pressurized upper chamber 19 is applied from the bypass passage 351 through the orifice 362A. In the extension stroke, the leaf spring 371 of the partition member 133E receives the pressure of the back pressure chamber 363 and seats the supported portion 371A on the valve seat 368A of the end cap 365. Along with this, the partition member 133E elastically deforms the elastic deflection portion 371B of the leaf spring 371 toward the concave surface 368B of the end cap 365, expanding the volume of the back pressure chamber 363 while reducing the volume of the chamber 402.

[0268] In the reverse compression stroke, the pressure of the pressurized lower chamber 20 acts on the leaf spring 371 through the chamber 402 from the communication hole 403 that opens into the lower chamber 20 of the end cap 365. Therefore, the partition member 133E causes the support spring 372 to deflect, separating the supported portion 371A of the leaf spring 371 from the valve seat 368A of the end cap 365, enabling the pressure of the lower chamber 20 to be introduced into the back pressure chamber 363.

[0269] The partition member 133E repeats the above-described extension stroke and compression stroke. In the extension stroke, it increases the volume of the back pressure chamber 363, causing a delay in the propagation of the pressure in the upper chamber 19. The partition member 133E can independently set the spring constants of the leaf spring 371 and the support spring 372. By reducing the number of stacked sheets of the leaf spring 371 and setting the extension side to be weak, a pressure propagation delay from the upper chamber 19 to the back pressure chamber 363 can be generated, and the response speed of the damping force of the piston valve device 320 and the extension side damping force adjustment mechanism 350 can be adjusted.

[0270] The partition member 133E is provided in the second passage 191E and partitions the second passage 191E between the back pressure chamber 363 and the chamber 402. At the same time, the partition member 133E is displaced by the oil fluid L flowing in due to the movement of the piston 18E, and discharges at least a part of the oil fluid L in the second passage 191E to the lower chamber 20 in the cylinder 2.

[0271] Therefore, the shock absorber 1E is provided with an extension side damping force adjustment mechanism 350 and operates as follows.

[0272] In the extension stroke, when the movement of the piston 18E of the shock absorber 1E is in the normal low-frequency large stroke range, the pressure of the pressurized upper chamber 19 is transmitted to the back pressure chamber 363 with almost no pressure propagation delay due to the orifice 362A, pushing and stroking the leaf spring 371 of the partition member 133E. Then, when the pressure in the back pressure chamber 363 rises, the sub-extension side damping valve 360 that receives the pressure of this back pressure chamber 363 does not open, and the main extension side damping valve 333 opens to generate a damping force. The main extension side damping valve 333 has a higher flexural rigidity than the sub-extension side damping valve 360 to ensure good handling stability during normal driving and generates the necessary damping force.

[0273] During the extension stroke, when the vehicle rides over the unevenness of the road surface and the movement of the piston 18E enters the high-frequency minute stroke region, the pressure in the pressurized upper chamber 19 is accompanied by a pressure propagation delay due to the orifice 362A and does not increase the pressure in the back pressure chamber 363, and the sub-extension side damping valve 360 becomes easy to open and reduces the damping force.

[0274] During the compression stroke, the compression side damping valve 334 opens to generate a damping force.

[0275] Here, during the extension stroke, when the displacement of the leaf spring 371 of the partition member 133E is smaller than a predetermined amount, the valve closing portion 167E is separated from the flat surface 368D of the end cap 365, and thus, the hydraulic fluid L flows from the entire chamber 402 to the lower chamber 20 through the communication hole 403.

[0276] On the other hand, during the extension stroke, when the displacement of the leaf spring 371 of the partition member 133E is equal to or greater than a predetermined amount, the valve closing portion 167E has the closing portion 408 in contact with the flat surface 368D of the end cap 365 over the entire circumference, and forms a closed pressure chamber radially outside the valve closing portion 167E of the chamber 402. This pressure chamber does not communicate with the lower chamber 20.

[0277] That is, in the extension-side damping force adjustment mechanism 350, the leaf spring 371 of the partition member 133E is displaced by the hydraulic fluid L flowing into the back pressure chamber 363 due to the movement of the piston 18E in the extension stroke, and at least a part of the hydraulic fluid L in the chamber 402 constituting the second passage 191E is discharged into the lower chamber 20 in the cylinder 2. Further, in the extension-side damping force adjustment mechanism 350, the closing valve portion 167E forms a pressure chamber blocked between the flat surface 368D in the second passage 191E of the end cap 365 and the partition member 133E, and restricts the movement of the hydraulic fluid L in the pressure chamber. The pressure chamber is formed by the contact between the closing valve portion 167E and the flat surface 368D in the second passage 191E of the end cap 365 due to the displacement of the leaf spring 371 of the partition member 133E. The closing valve portion 167E is provided on the leaf spring 371 of the partition member 133E, and is formed by an elastic member that contacts the flat surface 368D of the end cap 365 of the second passage 191E after the displacement of the leaf spring 371 and is deformed so that the leaf spring 371 can still be displaced after the contact. The extension-side damping force adjustment mechanism 350 is provided with the partition member 133E in the second passage 191E. The partition member 133E partitions the second passage 191E between the back pressure chamber 363 and the chamber 402.

[0278] The shock absorber 1E of the sixth embodiment is provided with an extension damping force adjustment mechanism 350 for varying the damping force in the second passage 191E, and forms a pressure chamber closed between the flat surface 368D in the second passage 191E of the end cap 365 and the leaf spring 371 of the partition member 133E, and has a closed valve portion 167E for restricting the movement of the hydraulic fluid L in the pressure chamber. When the pressure in the back pressure chamber 363 on the side opposite to the pressure chamber of the partition member 133E in the second passage 191E increases, the shock absorber 1E forms a pressure chamber closed between the inside of the second passage 191E and the leaf spring 371 of the partition member 133E, and accordingly, the pressure in the pressure chamber increases following this, suppressing the displacement of the leaf spring 371 of the partition member 133E. Thus, since the shock absorber 1E can suppress the displacement of the partition member 133E, the durability of the partition member 133E can be improved. Further, since the shock absorber 1E suppresses the displacement of the partition member 133E by the pressure of the hydraulic fluid L, generation of abnormal noise can be suppressed. Further, since the shock absorber 1E can gently suppress the displacement of the partition member 133E by the pressure of the hydraulic fluid L, a deterioration in riding comfort caused by a sudden change in the damping force can be suppressed.

[0279] Further, in the shock absorber 1E, the pressure chamber is formed by the flat surface 368D in the second passage 191E of the end cap 365 and the closed valve portion 167E coming into contact with each other due to the displacement of the leaf spring 371 of the partition member 133E. The shock absorber 1E forms the pressure chamber in this way due to the displacement of the leaf spring 371 of the partition member 133E. Therefore, the shock absorber 1E can easily displace the partition member 133E without forming a pressure chamber due to the displacement of the partition member 133E to vary the damping force, or can form a pressure chamber to suppress the displacement of the partition member 133E.

[0280] Further, in the shock absorber 1E, the valve closing portion 167E is provided on the leaf spring 371 of the partitioning member 133E, and after the displacement of the leaf spring 371, it abuts against the flat surface 368D of the end cap 365 of the second passage 191E, and is formed by an elastic member that deforms so that the leaf spring 371 can still be displaced after the abutment. Therefore, the shock absorber 1E can easily form a pressure chamber by the displacement of the partitioning member 133E, and can suppress the displacement of the partitioning member 133E more gently when suppressing the displacement.

[0281] [Seventh Embodiment] Next, the seventh embodiment will be mainly described with reference to FIG. 10, focusing on the differences from the sixth embodiment. For the parts common to the sixth embodiment, the same names and the same reference numerals are used.

[0282] As shown in FIG. 10, the shock absorber 1F of the seventh embodiment has a piston valve device 320F that is partially different from this instead of the piston valve device 320. The piston valve device 320F has an extension-side damping force adjustment mechanism 350F (second damping force mechanism) that is partially different from this instead of the extension-side damping force adjustment mechanism 350. The extension-side damping force adjustment mechanism 350F has a partitioning member 133F that is partially different from this instead of the partitioning member 133E. The partitioning member 133F is different from the partitioning member 133E in that the valve closing portion 167E is not provided.

[0283] The extension-side damping force adjustment mechanism 350F is provided with an annular valve closing portion 167F surrounding a small-diameter hole 382 on a flat surface 368D of a concave surface 368B of an end cap 365. The valve closing portion 167F is made of an elastic sealing material. The valve closing portion 167F is made of rubber and is annular. The inner peripheral portion of the valve closing portion 167B has an inner diameter that increases as it moves away from the flat surface 368D in the axial direction of the end cap 365. The outer peripheral portion of the valve closing portion 167F has an outer diameter that decreases as it moves away from the flat surface 368D in the axial direction of the valve seat member 142B. Therefore, the cross-sectional shape of the valve closing portion 167F in a plane including the central axis of the end cap 365 is a tapered mountain shape that becomes thinner as it moves away from the flat surface 368D in the axial direction of the end cap 365. The cross-sectional shape of the valve closing portion 167F in a plane including its central axis is the same shape throughout the entire circumference.

[0284] As shown in FIG. 10, when the leaf spring 371 of the partition member 133F is separated from the valve closing portion 167F, the entire chamber 402 communicates with the lower chamber 20 through the communication hole 403 of the end cap 365.

[0285] When the leaf spring 371 of the partition member 133F deflects toward the flat surface 368D side of the end cap 365, the leaf spring 371 abuts against the entire circumference of the valve closing portion 167F. Then, the leaf spring 371 closes the communication hole 403. In this state, the chamber 402 forms a pressure chamber closed on the radially outer side of the valve closing portion 167F. This pressure chamber does not communicate with the lower chamber 20.

[0286] In the extension stroke, the pressure of the pressurized upper chamber 19 is applied to the leaf spring 371 of the partition member 133F through the orifice 362A from the bypass passage 351. In the extension stroke, the partition member 133F has the leaf spring 371 receive the pressure of the back pressure chamber 363 and seats the supported portion 371A on the valve seat 368A of the end cap 365. The partition member 133E, together with that, elastically deforms the elastic deflection portion 371B of the leaf spring 371 toward the concave surface 368B of the end cap 365, expanding the volume of the back pressure chamber 363 while reducing the volume of the chamber 402.

[0287] The partition member 133F is provided in the second passage 191E and partitions the second passage 191E between the back pressure chamber 363 and the chamber 402. At the same time, the partition member 133F is displaced by the oil fluid L flowing in due to the movement of the piston 18E, and discharges at least a part of the oil fluid L in the second passage 191E to the lower chamber 20 in the cylinder 2.

[0288] In the extension stroke, when the displacement of the leaf spring 371 of the partition member 133F is smaller than a predetermined amount, the leaf spring 371 is separated from the closing valve portion 167F provided on the end cap 365. Therefore, the oil fluid L flows from the entire chamber 402 to the lower chamber 20 through the communication hole 403.

[0289] On the other hand, in the extension stroke, when the displacement of the leaf spring 371 of the partition member 133F is equal to or greater than a predetermined amount, the leaf spring 371 abuts on the entire circumference of the closing valve portion 167F of the end cap 365, and a closed pressure chamber is formed radially outside the closing valve portion 167F of the chamber 402. This pressure chamber does not communicate with the lower chamber 20.

[0290] That is, in the extension-side damping force adjustment mechanism 350F, the leaf spring 371 of the partition member 133F is displaced by the hydraulic fluid L flowing into the back pressure chamber 363 due to the movement of the piston 18E in the extension stroke, and at least a part of the hydraulic fluid L in the chamber 402 constituting the second passage 191E is discharged into the lower chamber 20 in the cylinder 2. Further, in the extension-side damping force adjustment mechanism 350F, the valve closing portion 167F forms a pressure chamber blocked between the flat surface 368D in the second passage 191E of the end cap 365 and the leaf spring 371 of the partition member 133F, and restricts the movement of the hydraulic fluid L in the pressure chamber. The pressure chamber is formed by the displacement of the leaf spring 371 of the partition member 133F when the leaf spring 371 and the valve closing portion 167F in the second passage 191E of the end cap 365 come into contact with each other. The valve closing portion 167F is provided on the flat surface 368D in the second passage 191E of the end cap 365, and after the displacement of the leaf spring 371 of the partition member 133F, it comes into contact with the leaf spring 371 and is formed by an elastic member that deforms so that the leaf spring 371 can still be displaced after the contact. The extension-side damping force adjustment mechanism 350F has the partition member 133F provided in the second passage 191E. The partition member 133F partitions the second passage 191E between the back pressure chamber 363 and the chamber 402.

[0291] The shock absorber 1F of the seventh embodiment is provided in the second passage 191E, and an extension damping force adjustment mechanism 350F for varying the damping force forms a pressure chamber closed between a flat surface 368D in the second passage 191E of the end cap 365 and a leaf spring 371 of the partition member 133F, and has a closing valve portion 167F that restricts the movement of the oil L in the pressure chamber. When the pressure in the back pressure chamber 363 on the side opposite to the pressure chamber of the leaf spring 371 in the second passage 191E increases, the shock absorber 1F forms a pressure chamber closed between the second passage 191E and the leaf spring 371 of the partition member 133F, and accordingly, the pressure in the pressure chamber increases following this, suppressing the displacement of the leaf spring 371. Thus, since the shock absorber 1F can suppress the displacement of the partition member 133F, the durability of the partition member 133F can be improved. Further, since the shock absorber 1F suppresses the displacement of the partition member 133F by the pressure of the oil L, the generation of abnormal noise can be suppressed. Further, since the shock absorber 1F can gently suppress the displacement of the partition member 133F by the pressure of the oil L, the deterioration of the riding comfort caused by a sudden change in the damping force can be suppressed.

[0292] Further, in the shock absorber 1F, the pressure chamber is formed by the displacement of the leaf spring 371 of the partition member 133F such that the leaf spring 371 and the closing valve portion 167F provided on the end cap 365 come into contact with each other. The shock absorber 1F forms the pressure chamber in this way by the displacement of the leaf spring 371 of the partition member 133F. Therefore, the shock absorber 1F can easily displace the partition member 133F without forming a pressure chamber by the displacement of the partition member 133F to vary the damping force, or can form a pressure chamber to suppress the displacement of the partition member 133F.

[0293] Further, the closing valve portion 167F of the shock absorber 1F is provided on the flat surface 368D in the second passage 191E of the end cap 365, and after the displacement of the leaf spring 371 of the partition member 133F, it comes into contact with the leaf spring 371 and is formed by an elastic member that deforms so that the leaf spring 371 can still be displaced after the contact. Therefore, when suppressing the displacement of the partition member 133F, the shock absorber 1F can suppress it more gently.

[0294] [Eighth Embodiment] Next, the differences between the eighth embodiment and the first embodiment will be mainly described with reference to FIG. 11, focusing on the parts that are different. For the parts common to the first embodiment, the same names and the same reference numerals are used.

[0295] As shown in FIG. 11, the shock absorber 1G of the eighth embodiment has a frequency-sensitive mechanism 130G (second damping force mechanism) that is partially different from the frequency-sensitive mechanism 130 in place of the frequency-sensitive mechanism 130.

[0296] The frequency-sensitive mechanism 130G has a valve case 145G that is partially different from the valve case 145 in place of the valve case 145. The valve case 145G has a case member 131G that is partially different from the case member 131 in place of the case member 131. The case member 131G has a cylindrical portion 153G in place of the cylindrical portion 153. The axial length of the cylindrical portion 153G is shorter than that of the cylindrical portion 153.

[0297] The valve case 145G has a lid member 143G in place of the disks 132, 135 to 137. The lid member 143G is a perforated disc-shaped made of metal. The lid member 143G fits onto the mounting shaft portion 28 of the piston rod 21.

[0298] The lid member 143G has a substrate portion 422, an inner sheet portion 423, and an outer sheet portion 424.

[0299] The substrate portion 422 is a perforated disc shape. The outer diameter of the substrate portion 422 is constant over the entire circumference, and the radial width is constant over the entire circumference. The lid member 143G has the substrate portion 422 fitting onto the mounting shaft portion 28 of the piston rod 21. A passage hole 431 that penetrates the substrate portion 422 in the axial direction is formed at an intermediate position in the radial direction of the substrate portion 422. A plurality of passage holes 431 are formed at equal intervals in the circumferential direction of the substrate portion 422. The plurality of passage holes 431 are aligned in terms of their positions from the central axis of the substrate portion 422.

[0300] The inner sheet portion 423 is annular. The inner sheet portion 423 protrudes from the inner peripheral edge portion of the substrate portion 422 in one side along the axial direction of the substrate portion 422.

[0301] The outer sheet portion 424 is annular with a diameter larger than that of the inner sheet portion 423. The outer sheet portion 424 protrudes from the intermediate position in the radial direction of the substrate portion 422 in the same side as the inner sheet portion 423 along the axial direction of the substrate portion 422.

[0302] The height position of the tip of the outer sheet portion 424 in the axial direction of the substrate portion 422 is the same as the height position of the tip of the inner sheet portion 423. A plurality of passage holes 431 are formed in the substrate portion 422 between the inner sheet portion 423 and the outer sheet portion 424 in the radial direction thereof.

[0303] The valve case 145G is configured by abutting the case member 131G and the lid member 143G. At that time, the case member 131G and the lid member 143G are oriented such that the protruding portion 151, the inner sheet portion 423, and the outer sheet portion 424 face each other. And the portion outside the outer sheet portion 424 in the radial direction of the substrate portion 422 of the lid member 143G abuts against the cylindrical portion 153G of the case member 131G.

[0304] The frequency sensitive mechanism 130G has a partition member 133G different from the partition member 133 in place of the partition member 133. The partition member 133G has a valve disk 161G, an inner valve closing portion 435 (valve closing portion), and an outer valve closing portion 436 (valve closing portion).

[0305] The valve disk 161G is made of metal. The valve disk 161G is a perforated circular flat plate with a certain thickness. The valve disk 161G 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 is inserted through the inner peripheral side of the valve disk 161G. The valve disk 161G is elastically deformable, that is, bendable. The outer diameter of the valve disk 161G is slightly smaller than the inner diameter of the cylindrical portion 153G. The valve disk 161G is positioned radially with respect to the case member 131G at the inner peripheral portion of the cylindrical portion 153G. The valve disk 161G is guided by the inner peripheral portion of the cylindrical portion 153G and moves in the axial direction of the case member 131G.

[0306] The inner closing valve portion 435 is made of an elastic sealing material. The inner closing valve portion 435 is made of rubber and is annular. The inner closing valve portion 435 is coaxial with the valve disk 161G and is adhered to one side surface in the axial direction of the valve disk 161G by baking. The inner diameter of the inner peripheral portion of the inner closing valve portion 435 becomes larger as it moves away from the valve disk 161G in the axial direction of the valve disk 161G. The outer diameter of the outer peripheral portion of the inner closing valve portion 435 becomes smaller as it moves away from the valve disk 161G in the axial direction of the valve disk 161G. Therefore, the cross-sectional shape of the inner closing valve portion 435 in the plane including the central axis of the valve disk 161G is a tapered single mountain shape that becomes thinner as it moves away from the valve disk 161G in the axial direction of the valve disk 161G. The cross-sectional shape of the inner closing valve portion 435 in the plane including its central axis is the same over the entire circumference.

[0307] The outer closing part 436G is made of an elastic sealing material. The outer closing part 436 is made of rubber and is an annular shape with a larger diameter than the inner closing part 435. The outer closing part 436 is coaxial with the valve disk 161G and is adhesively bonded by baking to the surface on the same side as the inner closing part 435 in the axial direction of the valve disk 161G. The inner peripheral part of the outer closing part 436 has an inner diameter that increases as it moves away from the valve disk 161G in the axial direction of the valve disk 161G. The outer peripheral part of the outer closing part 436 has an outer diameter that decreases as it moves away from the valve disk 161G in the axial direction of the valve disk 161G. Therefore, the cross-sectional shape of the outer closing part 436 in the plane containing the central axis of the valve disk 161G is a tapered mountain shape that becomes thinner as it moves away from the valve disk 161G in the axial direction of the valve disk 161G. The cross-sectional shape of the outer closing part 436 in the plane containing its central axis is the same throughout the entire circumference. The inner closing part 435 and the outer closing part 436 have the same protruding height from the valve disk 161G.

[0308] The partitioning member 133G is arranged inside the valve case 145G in a direction in which the inner closing part 435 and the outer closing part 436 protrude toward the lid member 143G side in the axial direction of the valve case 145G. Then, the inner closing part 435 is arranged outside the inner sheet part 423 in the radial direction of the lid member 143G and inside the passage hole 431. Also, the outer closing part 436 is arranged inside the outer sheet part 424 in the radial direction of the lid member 143G and outside the passage hole 431. The frequency sensing mechanism 130G has a spring member 437. The spring member 437 is made of metal and has a substrate portion 438 and a spring plate portion 439. The substrate portion 438 is in the shape of a perforated disc flat plate. A plurality of, specifically five, spring plate portions 439 are provided at equal intervals in the circumferential direction of the substrate portion 438. The spring plate portion 439 extends radially outward from the substrate portion 438. The spring plate portion 439 is inclined with respect to the substrate portion 438 such that the farther it is located outward in the radial direction of the substrate portion 438, the farther it is away from the substrate portion 438 in the axial direction of the substrate portion 438. For the spring member 437, the substrate portion 438 fits onto the mounting shaft portion 28 of the piston rod 21. The spring member 437 is provided between the protruding portion 151 and the partitioning member 133G. For the spring member 437, the substrate portion 438 abuts against the protruding portion 151, and the spring plate portion 439 abuts against the valve disc 161G of the partitioning member 133G. Thereby, the spring member 437 presses the valve disc 161G against the inner seat portion 423 and the outer seat portion 424.

[0309] For the partitioning member 133G, the portion inside the inner valve closing portion 435 in the radial direction of the valve disc 161G abuts against the inner seat portion 423, and the portion outside the outer valve closing portion 436 in the radial direction of the valve disc 161G abuts against the outer seat portion 424. In this state, the partitioning member 133G closes the passage hole 431. Further, when the valve disc 161G moves away from the inner seat portion 423 and the outer seat portion 424 against the biasing force of the spring member 437, the partitioning member 133G opens the passage hole 431. The valve disc 161G, the inner seat portion 423, the outer seat portion 424, and the spring member 437 constitute a check valve 193G.

[0310] The shock absorber 1G has an annular member 138G with an outer diameter smaller than that of the annular member 138 instead.

[0311] The partition member 133G is provided in the valve case 145G and partitions the inside of the valve case 145G into a first chamber 181 and a second chamber 182. The first chamber 181 is between the bottom portion 150 in the axial direction of the valve case 145G and the partition member 133G. The second chamber 182 is between the partition member 133G and the lid member 143G in the axial direction of the valve case 145G.

[0312] As shown in FIG. 11, when the inner valve closing portion 435 and the outer valve closing portion 436 of the partition member 133G are separated from the substrate portion 422 of the lid member 143G, the entire second chamber 182 communicates with the lower chamber 20 through the passage hole 431 in the substrate portion 422 of the lid member 143G.

[0313] When the partition member 133G is deformed into a tapered shape and the inner valve closing portion 435 and the outer valve closing portion 436 are in contact with the substrate portion 422 of the lid member 143G over the entire circumference, the second chamber 182 is partitioned into an inner pressure chamber radially inside the inner valve closing portion 435, an outer pressure chamber radially outside the outer valve closing portion 436, and a communication chamber at a position between the inner valve closing portion 435 and the outer valve closing portion 436 in the radial direction. This communication chamber communicates with the lower chamber 20 through the passage hole 431. These inner pressure chamber and outer pressure chamber do not communicate with the communication chamber, and thus do not communicate with the lower chamber 20 either.

[0314] In the extension stroke, the hydraulic fluid L from the upper chamber 19 (see FIG. 2) is introduced into the first chamber 181 through the first passage 43 (see FIG. 2), the passage in the notch 81 (see FIG. 2) of the disk 50 (see FIG. 2), the passage in the groove portion 30 of the piston rod 21 shown in FIG. 11, and the passage between the protruding portion 151 of the case member 131G and the partition member 133G. Then, the valve disk 161 of the partition member 133G bends with the contact points with the inner seat portion 423 and the outer seat portion 424 of the lid member 143G as fulcrums, so that the portion between them becomes concave toward the substrate portion 422 side.

[0315] Due to such displacement, the partition member 133G will increase the volume of the first chamber 181. Here, when the partition member 133G is displaced, the volume of the second chamber 182 will decrease. At that time, the hydraulic fluid L in the second chamber 182 flows into the lower chamber 20 through the passage hole 431.

[0316] Here, in the extension stroke, when the displacement of the partition member 133G is smaller than a predetermined amount, the inner closing valve portion 435 and the outer closing valve portion 436 are separated from the substrate portion 422 of the lid member 143G. Therefore, the hydraulic fluid L flows from the entire second chamber 182 into the lower chamber 20 through the passage hole 431.

[0317] On the other hand, in the extension stroke, when the displacement of the partition member 133G is equal to or greater than a predetermined amount, both the inner closing valve portion 435 and the outer closing valve portion 436 abut against the substrate portion 422 of the lid member 143G over the entire circumference, and the second chamber 182 is partitioned into an inner pressure chamber radially inside the inner closing valve portion 435, an outer pressure chamber radially outside the outer closing valve portion 436, and a communication chamber at a position between the inner closing valve portion 435 and the outer closing valve portion 436 in the radial direction. Therefore, although the communication chamber of the second chamber 182 communicates with the lower chamber 20 through the passage hole 431, neither the inner pressure chamber nor the outer pressure chamber communicates with the lower chamber 20.

[0318] That is, in the frequency sensing mechanism 130G, the partitioning member 133G is displaced by the hydraulic fluid L that has flowed into the first chamber 181 due to the movement of the piston 18 (see FIG. 2) during the extension stroke, and at least a part of the hydraulic fluid L in the second chamber 182 that constitutes a part of the second passage 191 is discharged into the lower chamber 20 in the cylinder 2 (see FIG. 2). Further, in the frequency sensing mechanism 130G, the inner closing valve portion 435 and the outer closing valve portion 436 form an inner pressure chamber and an outer pressure chamber that are blocked between the lid member 143G in the second passage 191 and the partitioning member 133G, and restrict the movement of the hydraulic fluid L in the inner pressure chamber and the outer pressure chamber. The inner pressure chamber and the outer pressure chamber are formed when the inner closing valve portion 435 and the outer closing valve portion 436 come into contact with the lid member 143G in the second passage 191 due to the displacement of the partitioning member 133G. The inner closing valve portion 435 and the outer closing valve portion 436 are provided on the partitioning member 133G, and are formed by elastic members that come into contact with the lid member 143G of the second passage 191 after the displacement of the partitioning member 133G and are deformed so that the partitioning member 133G can still be displaced after the contact. In the frequency sensing mechanism 130G, the partitioning member 133G is provided in the second passage 191. The partitioning member 133G partitions the second passage 191 between the first chamber 181 and the second chamber 182.

[0319] The shock absorber 1G varies the damping force in the same manner as the shock absorber 1 according to the piston frequency.

[0320] The shock absorber 1G of the eighth embodiment is provided in the second passage 191, and a frequency-sensitive mechanism 130G for varying the damping force forms an inner pressure chamber and an outer pressure chamber closed between a lid member 143G in the second passage 191 and a partitioning member 133G, and has an inner closing valve portion 435 and an outer closing valve portion 436 that restrict the movement of the hydraulic fluid L in the inner pressure chamber and the outer pressure chamber. When the pressure in the first chamber 181 on the side opposite to the inner pressure chamber and the outer pressure chamber of the partitioning member 133G in the second passage 191 becomes high, the shock absorber 1G forms the inner pressure chamber and the outer pressure chamber closed between the partitioning member 133G and the second passage 191, and accordingly, the pressure in the inner pressure chamber and the outer pressure chamber increases following this, suppressing the displacement of the partitioning member 133G. Thus, since the shock absorber 1G can suppress the displacement of the partitioning member 133G, the durability of the partitioning member 133G can be improved. Further, since the shock absorber 1G suppresses the displacement of the partitioning member 133G by the pressure of the hydraulic fluid L, generation of abnormal noise can be suppressed. Further, since the shock absorber 1G can gently suppress the displacement of the partitioning member 133G by the pressure of the hydraulic fluid L, a deterioration in the riding comfort caused by a rapid change in the damping force can be suppressed.

[0321] Further, in the shock absorber 1G, the inner pressure chamber and the outer pressure chamber are formed by contact between the lid member 143G in the second passage 191 and the inner closing valve portion 435 and the outer closing valve portion 436 due to the displacement of the partitioning member 133G. Thus, the shock absorber 1G forms the inner pressure chamber and the outer pressure chamber by the displacement of the partitioning member 133G. Therefore, the shock absorber 1G can easily displace the partitioning member 133G without forming a pressure chamber to vary the damping force, or can form a pressure chamber to suppress the displacement of the partitioning member 133G, depending on the displacement of the partitioning member 133G.

[0322] Further, the buffer 1G is formed by an elastic member in which the inner closing valve portion 435 and the outer closing valve portion 436 are provided on the partition member 133G, contact the lid member 143G of the second passage 191 after the displacement of the partition member 133G, and are deformed so that the partition member 133G can still be displaced after the contact. Therefore, the buffer 1G can easily form a pressure chamber by the displacement of the partition member 133G, and can suppress the displacement of the partition member 133G more gently when suppressing the displacement of the partition member 133G.

[0323] [Embodiment 9] Next, the differences between the ninth embodiment and the first embodiment will be mainly described with reference to FIG. 12. For parts common to the first embodiment, the same names and the same reference numerals are used.

[0324] As shown in FIG. 12, the buffer 1H has a piston rod 21H that is partially different from the piston rod 21 in place of the piston rod 21. The piston rod 21H has no groove portion 30 formed therein, and has a rod inner passage 30H that penetrates therethrough and extends from the outer peripheral surface of the main shaft portion 27H to the end portion on the side opposite to the main shaft portion 27H in the axial direction of the mounting shaft portion 28H. The main shaft portion 27H is different from the main shaft portion 27 in that a part of the rod inner passage 30H is formed therein and one end of the rod inner passage 30H opens to the outer peripheral surface. The mounting shaft portion 28H has no groove portion 30 formed therein, and is different from the mounting shaft portion 28 in that a part of the rod inner passage 30H is formed therein and the other end of the rod inner passage 30H opens to the end surface on the side opposite to the main shaft portion 27 in the axial direction. The rod inner passage 30H communicates with the upper chamber 19. The piston rod 21H also has the side opposite to the mounting shaft portion 28H in the axial direction of the main shaft portion 27H inserted through the rod guide 22 (see FIG. 1) and the seal member 23 (see FIG. 1) and extending outside the cylinder 2.

[0325] The shock absorber 1H has a piston 18H that is partially different from the piston 18, replacing the piston 18. The piston 18H has a piston body 35H that is partially different from the piston body 35, replacing the piston body 35. The piston body 35H is integrally formed, and is different from the piston body 35 in that an insertion hole 45H with a constant inner diameter is formed. The mounting shaft portion 28H of the piston rod 21H fits into the insertion hole 45H of the piston body 35H.

[0326] The shock absorber 1H is not provided with the disks 50, 53, 56, the pilot disk 52, the pilot case 55, and the disk valve 99. In the shock absorber 1H, a plurality of disks 51 constitute the disk valve 91H. And on the side of the disk valve 91H opposite to the piston 18H, the disks 58, 59, and the annular member 138 are provided in this order. The disk valve 91H constitutes the extension-side damping force mechanism 41H (first damping force mechanism). The damping force mechanism 41H is different from the damping force mechanism 41 in that it has a disk valve 91H to which no back pressure is applied instead of the damping valve 91, and is not provided with a configuration for applying back pressure.

[0327] Also, the shock absorber 1H has a frequency-sensitive mechanism 130H (second damping force mechanism) that is different from the frequency-sensitive mechanism 130, replacing the frequency-sensitive mechanism 130 and the nut 195.

[0328] The frequency-sensitive mechanism 130H has a lid member 451, a housing body 452, a partitioning member 133H, a first spring 454, and a second spring 455.

[0329] The lid member 451 is made of metal and has a lid cylinder portion 461 and a lid substrate portion 462. The lid cylinder part 461 is cylindrical. The lid substrate part 462 is disc-shaped and extends radially outward from one axial end of the lid cylinder part 461. A thread 465 is formed on the inner peripheral part of the lid cylinder part 461. The lid member 451 is screwed onto the threaded part 31 of the piston rod 21H at the thread 465. The lid member 451 serves as a nut and clamps at least the inner peripheral side of the components from the annular member 115 to the annular member 138. That is, the lid member 451 also serves as a nut.

[0330] The housing body 452 is made of metal and is generally a bottomed cylindrical shape. The lid member 451 is attached to the housing body 452 so as to close one end opening side of the housing body 452. The housing body 452 has a main body cylinder part 471 and a main body bottom part 472.

[0331] The main body cylinder part 471 is cylindrical. One end of the main body cylinder part 471 opposite to the main body bottom part 472 is a thin-walled part 475, and the part excluding the thin-walled part 475 is a thick-walled part 476 thicker than the thin-walled part 475. Before the lid member 451 is assembled, the thin-walled part 475 extends on the axial extension of the thick-walled part 476. In this state, the thick-walled part 476 has substantially the same outer diameter and a smaller inner diameter than the thin-walled part 475.

[0332] The main body bottom part 472 is disc-shaped and closes one axial end of the main body cylinder part 471. A passage hole 478 penetrating in the axial direction is formed at the center in the radial direction on the main body bottom part 472.

[0333] The lid member 451 is fitted into the housing body 452 with the lid cylinder part 461 at the front inside the thin-walled part 475 extending on the axial extension of the thick-walled part 476. Then, the housing body 452 is caulked and bent radially inward as shown in FIG. 12. Thereby, the housing body 452 and the lid member 451 are integrated to form the housing 481.

[0334] The partition member 133H is a free piston slidably inserted into the housing 481. The partition member 133H has a partition member main body 491, a seal member 492, a first valve closing portion 493 (valve closing portion), and a second valve closing portion 494 (valve closing portion).

[0335] The partition member main body 491 is made of metal and has a piston cylinder portion 501, a piston closing plate portion 502, and a piston extending portion 503.

[0336] The piston cylinder portion 501 is cylindrical. An annular seal holding groove 505 that is recessed radially inward is formed in the outer peripheral portion on one end side in the axial direction of the piston cylinder portion 501.

[0337] The piston closing plate portion 502 is disk-shaped and closes the central position in the axial direction of the piston cylinder portion 501.

[0338] The piston extending portion 503 is columnar and extends from the central position in the radial direction of the piston closing plate portion 502 to one side in the axial direction of the piston closing plate portion 502. The piston extending portion 503 extends from the piston closing plate portion 502 to the side opposite to the seal holding groove 505 in the axial direction of the piston closing plate portion 502. The piston extending portion 503 is provided coaxially with the piston cylinder portion 501 inside the radial direction of the piston cylinder portion 501.

[0339] The partition member main body 491 is slidably fitted to the main body cylinder portion 471 of the housing main body 452 in the piston cylinder portion 501. At that time, the partition member main body 491 is oriented such that the piston extending portion 503 extends from the piston closing plate portion 502 toward the main body bottom portion 472 side in the axial direction of the piston closing plate portion 502.

[0340] The seal member 492 is annular and is fitted and held in the seal holding groove 505 of the partition member main body 491. The seal member 492 seals the gap between the piston cylinder portion 501 of the partition member main body 491 and the main body cylinder portion 471 of the housing 481. The seal member 492 is a square ring whose cross section in a plane including the central axis is square-shaped.

[0341] The first valve closing part 493 is provided on the surface of the piston closing plate part 502 on the side opposite to the piston extending part 503 in the axial direction. The first valve closing part 493 is provided at the central position in the radial direction of the piston closing plate part 502. The first valve closing part 493 is made of rubber and is disc-shaped. The first valve closing part 493 is baked and adhered to the piston closing plate part 502. The first valve closing part 493 has an annular closing part 495 that protrudes axially from the inner side at the outer peripheral edge part. The cross-sectional shape of the first valve closing part 493 in the plane including its central axis is the same shape throughout the entire circumference.

[0342] The second valve closing part 494 is provided on the end face of the piston extending part 503 on the side opposite to the piston closing plate part 502 in the axial direction. The second valve closing part 494 is made of rubber and is disc-shaped. The second valve closing part 494 is baked and adhered to the piston extending part 503. The second valve closing part 494 has an annular closing part 496 that protrudes axially from the inner side at the outer peripheral edge part. The cross-sectional shape of the second valve closing part 494 in the plane including its central axis is the same shape throughout the entire circumference.

[0343] The first spring 454 is coiled and is interposed between the piston closing plate part 502 of the partition member 133H and the lid substrate part 462 of the housing 481. The first spring 454 is compressed and deformed when the partition member 133H moves toward the lid substrate part 462 side within the housing 481. That is, the first spring 454 is a resistance element that is compressed and deformed when the partition member 133H moves toward the lid substrate part 462 side and generates a resistance force against the displacement of the partition member 133H.

[0344] The second spring 455 is coiled and is interposed between the piston closing plate portion 502 of the partitioning member 133H and the main body bottom portion 472 of the housing 481. The second spring 455 is compressed and deformed when the partitioning member 133H moves toward the main body bottom portion 472 side within the housing 481. That is, the second spring 455 is a resistance element that is compressed and deformed when the partitioning member 133H moves toward the main body bottom portion 472 side and generates a resistance force against the displacement of the partitioning member 133H.

[0345] These first spring 454 and second spring 455 bias the partitioning member 133H to hold it at the neutral position within the housing 481.

[0346] The partitioning member 133H is provided within the housing 481 and partitions the interior of the housing 481 into a first chamber 181H and a second chamber 182H.

[0347] The first chamber 181H is located between the lid member 451 and the partitioning member 133H in the axial direction of the housing 481. The first chamber 181H can communicate with the upper chamber 19 via the rod inner passage 30H. The first chamber 181H has a variable volume, and the volume changes with the displacement caused by the movement of the partitioning member 133H.

[0348] The second chamber 182H is located between the main body bottom portion 472 of the housing main body 452 and the partitioning member 133H in the axial direction of the housing 481. The second chamber 182H can communicate with the lower chamber 20 via the passage within the passage hole 478 of the main body bottom portion 472. The second chamber 182H has a variable volume, and the volume changes with the displacement caused by the movement of the partitioning member 133H.

[0349] The rod inner passage 30H, the first chamber 181H, the second chamber 182H, and the passage in the passage hole 478 constitute the second passage 191H. The second passage 191H is formed in parallel with the first passages 43, 44. The second passage 191H is provided so that the oil fluid L can flow in from the upper chamber 19 and the lower chamber 20 by the movement of the piston 18H. The passage hole 478 also has the function of an introduction orifice. By using this as the introduction orifice and changing the size of the passage hole 478, the variable range of the frequency sensitivity of the frequency sensitivity mechanism 130H can be adjusted.

[0350] As shown in FIG. 12, when the second valve closing portion 494 of the partition member 133H is separated from the main body bottom portion 472 of the housing main body 452, the entire second chamber 182H communicates with the lower chamber 20 through the passage in the passage hole 478.

[0351] As shown in FIG. 12, when the first valve closing portion 493 of the partition member 133H is separated from the piston rod 21H, the entire first chamber 181H communicates with the upper chamber 19 through the rod inner passage 30H.

[0352] When the second valve closing portion 494 of the partition member 133H is in contact with the main body bottom portion 472 of the housing main body 452 over the entire circumference at the closing portion 496, the second valve closing portion 494 closes the end portion on the second chamber 182H side of the passage in the passage hole 478 of the main body bottom portion 472. In this state, the second chamber 182H forms a closed second pressure chamber radially outside the second valve closing portion 494. The second pressure chamber does not communicate with the lower chamber 20.

[0353] When the first valve closing portion 493 of the partition member 133H is in contact with the piston rod 21H over the entire circumference at the closing portion 495, the first valve closing portion 493 closes the end portion on the first chamber 181H side of the rod inner passage 30H. In this state, the first chamber 181H forms a closed first pressure chamber radially outside the first valve closing portion 493. The first pressure chamber does not communicate with the upper chamber 19.

[0354] In the extension stroke, the hydraulic fluid L from the upper chamber 19 is introduced into the first chamber 181H through the rod internal passage 30H of the piston rod 21H. Then, the partitioning member 133H moves so as to approach the main body bottom portion 472 within the housing 481. At that time, the partitioning member 133H axially compresses and deforms the second spring 455 interposed between it and the main body bottom portion 472 within the housing 481.

[0355] Due to the displacement as described above, the partitioning member 133H will increase the volume of the first chamber 181H. Here, when the partitioning member 133H is displaced, the volume of the second chamber 182H will decrease. At that time, the hydraulic fluid L in the second chamber 182H flows into the lower chamber 20 through the passage in the passage hole 478.

[0356] Here, in the extension stroke, when the displacement of the partitioning member 133H is smaller than a predetermined amount, the second closing valve portion 494 is separated from the main body bottom portion 472 of the housing 481. Therefore, the hydraulic fluid L flows from the entire second chamber 182H into the lower chamber 20 through the passage in the passage hole 478.

[0357] On the other hand, in the extension stroke, when the displacement of the partitioning member 133H is equal to or greater than a predetermined amount, the second closing valve portion 494 abuts against the main body bottom portion 472 of the housing 481 over the entire circumference at the closing portion 496, and a second pressure chamber closed radially outside the second closing valve portion 494 is formed in the second chamber 182H. This second pressure chamber does not communicate with the lower chamber 20.

[0358] That is, in the frequency sensing mechanism 130H, the partitioning member 133H is displaced by the hydraulic fluid L that has flowed into the first chamber 181H due to the movement of the piston 18H during the extension stroke, and discharges at least a part of the hydraulic fluid L in the second chamber 182H that constitutes the second passage 191H into the lower chamber 20 in the cylinder 2. Further, in the frequency sensing mechanism 130H, the second closing valve portion 494 forms a closed second pressure chamber between the main body bottom portion 472 in the second passage 191H of the housing 481 and the partitioning member 133H, and restricts the movement of the hydraulic fluid L in the second pressure chamber. The second pressure chamber is formed when the partitioning member 133H is displaced and the second closing valve portion 494 comes into contact with the main body bottom portion 472 in the second passage 191H. The second closing valve portion 494 is provided on the partitioning member 133H and is formed by an elastic member that comes into contact with the main body bottom portion 472 of the second passage 191H after the displacement of the partitioning member 133H and is deformed so that the partitioning member 133H can still be displaced after contact. In the frequency sensing mechanism 130H, the partitioning member 133H is provided in the second passage 191H. The partitioning member 133H partitions the second passage 191H between the first chamber 181H and the second chamber 182H.

[0359] During the extension stroke, the shock absorber 1H varies the damping force according to the piston frequency, similar to the shock absorber 1.

[0360] During the compression stroke, the hydraulic fluid L from the lower chamber 20 is introduced into the second chamber 182H through the passage in the passage hole 478 of the housing 481. Then, the partitioning member 133H moves so as to approach the lid substrate portion 462 of the lid member 451 within the housing 481. At that time, the partitioning member 133H compresses and deforms the first spring 454 interposed between it and the lid substrate portion 462 in the axial direction of the housing 481.

[0361] Due to the displacement as described above, the partitioning member 133H increases the volume of the second chamber 182H. Here, when the partitioning member 133H is displaced, the volume of the first chamber 181H decreases. At that time, the hydraulic fluid L in the first chamber 181H flows into the upper chamber 19 through the rod inner passage 30H.

[0362] Here, in the compression stroke, when the displacement of the partition member 133H is smaller than a predetermined amount, the first valve closing portion 493 is separated from the piston rod 21H. Therefore, the hydraulic fluid L flows from the entire first chamber 181H through the rod inner passage 30H into the upper chamber 19.

[0363] On the other hand, in the compression stroke, when the displacement of the partition member 133H is equal to or greater than a predetermined amount, the first valve closing portion 493 abuts against the piston rod 21H over the entire circumference at the closing portion 495, and a first pressure chamber closed radially outside the first valve closing portion 493 is formed in the first chamber 181H. This first pressure chamber does not communicate with the upper chamber 19.

[0364] That is, the frequency sensing mechanism 130H causes the partition member 133H to be displaced by the hydraulic fluid L that has flowed into the second chamber 182H due to the movement of the piston 18H in the compression stroke, and discharges at least a part of the hydraulic fluid L in the first chamber 181H into the upper chamber 19 in the cylinder 2. Further, the frequency sensing mechanism 130H forms a closed first pressure chamber between the lid substrate portion 462 in the second passage 191H of the housing 481 and the partition member 133H, and restricts the movement of the hydraulic fluid L in the first pressure chamber. The first pressure chamber is formed by the partition member 133H being displaced so that the first valve closing portion 493 abuts against the piston rod 21H in the second passage 191H. The first valve closing portion 493 is provided on the partition member 133H, and is formed by an elastic member that abuts against the piston rod 21H in the second passage 191H after the displacement of the partition member 133H and is deformed so that the partition member 133H can still be displaced after the abutment.

[0365] The shock absorber 1H also varies the damping force according to the piston frequency in the compression stroke, becoming soft at high frequencies and hard at low frequencies.

[0366] In the shock absorber 1H of the ninth embodiment, a frequency-sensitive mechanism 130H provided in the second passage 191H for varying the damping force forms a second pressure chamber closed between the main body bottom 472 in the second passage 191H and the partitioning member 133H, and has a second check valve portion 494 for restricting the movement of the hydraulic fluid L in the second pressure chamber. When the pressure in the first chamber 181H on the side opposite to the second pressure chamber of the partitioning member 133H in the second passage 191H increases, the shock absorber 1H causes the pressure in the second pressure chamber to increase accordingly by the second check valve portion 494 forming the second pressure chamber closed between the inside of the second passage 191H and the partitioning member 133H, thereby suppressing the displacement of the partitioning member 133H.

[0367] Further, in the shock absorber 1H, the frequency-sensitive mechanism 130H forms a first pressure chamber closed between the lid substrate portion 462 in the second passage 191H and the partitioning member 133H, and has a first check valve portion 493 for restricting the movement of the hydraulic fluid L in the first pressure chamber. When the pressure in the second chamber 182H on the side opposite to the first pressure chamber of the partitioning member 133H in the second passage 191H increases, the shock absorber 1H causes the pressure in the first pressure chamber to increase accordingly by the first check valve portion 493 forming the first pressure chamber closed between the inside of the second passage 191H and the partitioning member 133H, thereby suppressing the displacement of the partitioning member 133H.

[0368] Since the shock absorber 1H can suppress the displacement of the partitioning member 133H in both the extension stroke and the compression stroke, the durability of the partitioning member 133H can be improved. Further, since the shock absorber 1H suppresses the displacement of the partitioning member 133H by the pressure of the hydraulic fluid L, the generation of abnormal noise can be suppressed. Further, since the shock absorber 1H can gently suppress the displacement of the partitioning member 133H by the pressure of the hydraulic fluid L, the deterioration of the riding comfort caused by a sudden change in the damping force can be suppressed.

[0369] Further, in the shock absorber 1H, the second pressure chamber is formed by the main body bottom 472 in the second passage 191H and the second check valve portion 494 coming into contact with each other due to the displacement of the partitioning member 133H. The shock absorber 1H forms the second pressure chamber in this way due to the displacement of the partitioning member 133H. Further, in the shock absorber 1H, the first pressure chamber is formed by the displacement of the partitioning member 133H causing the piston rod 21H in the second passage 191H to contact the first closing valve portion 493. The shock absorber 1H forms the first pressure chamber by the displacement of the partitioning member 133H in this manner. Therefore, in both the extending stroke and the contracting stroke, the shock absorber 1H can easily displace the partitioning member 133H without forming the first pressure chamber and the second pressure chamber by the displacement of the partitioning member 133H to vary the damping force, or can form the first pressure chamber or the second pressure chamber to suppress the displacement of the partitioning member 133H.

[0370] Also, in the shock absorber 1H, the second closing valve portion 494 is provided on the partitioning member 133H, contacts the main body bottom portion 472 of the second passage 191H after the displacement of the partitioning member 133H, and is formed by an elastic member that deforms so that the partitioning member 133H can still be displaced after the contact. Also, in the shock absorber 1H, the first closing valve portion 493 is provided on the partitioning member 133H, contacts the piston rod 21H of the second passage 191H after the displacement of the partitioning member 133H, and is formed by an elastic member that deforms so that the partitioning member 133H can still be displaced after the contact. Therefore, the shock absorber 1H can easily form the first pressure chamber and the second pressure chamber by the displacement of the partitioning member 133H, and can suppress the displacement of the partitioning member 133H more gently when suppressing the displacement of the partitioning member 133H in both the extending stroke and the contracting stroke.

[0371] In the first to ninth embodiments, a hydraulic shock absorber is shown as an example, but the above structure can also be adopted for shock absorbers using water or air as the working fluid.

Industrial Applicability

[0372] According to the shock absorber according to each of the above aspects of the present invention, the durability of the partitioning member can be improved. Therefore, the industrial applicability is great.

Explanation of Reference Numerals

[0373] 1, 1C to 1H... buffer, 2... cylinder, 18, 18H, 18E... piston, 19... upper chamber, 20... lower chamber, 21, 21E, 21H... piston rod, 41, 41E, 41H, 42, 42E... damping force mechanism (first damping force mechanism), 43, 43E, 44, 44E... first passage, 130, 130A to 130D, 130G, 130H... frequency sensitive mechanism (second damping force mechanism), 133, 133A to 133H... partitioning member, 167, 167A to 167F... closing valve portion, 187... pressure chamber, 191, 191E, 191H... second passage, 350, 350F... extension side damping force adjustment mechanism (second damping force mechanism), 435... inner closing valve portion (closing valve portion), 436... outer closing valve portion (closing valve portion), 493... first closing valve portion (closing valve portion), 494... second closing valve portion (closing valve portion).

Claims

1. A cylinder in which a working fluid is sealed; a piston slidably fitted in the cylinder and dividing the cylinder into two chambers; a piston rod connected to the piston and extending outside the cylinder; a first passage that communicates the two chambers by movement of the piston so that the working fluid can flow between the two chambers; a second passage formed in parallel with the first passage and configured to allow the working fluid of at least one of the two chambers to flow therein by movement of the piston; a first damping force mechanism provided in the first passage and configured to generate a damping force; a partition member that is provided in the second passage and comprises a plate-shaped disk and an elastic member provided on the outer periphery of the disk, the inner periphery of the disk being supported by a support member on only one side without being clamped from both sides, partitioning the second passage and being displaced by the working fluid that has flowed in due to the movement of the piston, and discharging at least a part of the working fluid in the second passage into the cylinder, a closed pressure chamber formed in the second passage by the position of the partition member, and a valve closing portion that limits the movement of the working fluid in the pressure chamber, and a second damping force mechanism that varies a damping force; A shock absorber comprising:

2. The shock absorber according to claim 1 , wherein the pressure chamber is formed by abutting the partition member or a member that defines the second passage against the valve closing portion due to displacement of the partition member.

3. 2. The shock absorber according to claim 1, wherein the valve closing portion is formed by an elastic member that is provided on the partition member, abuts against a member that forms the second passage after the partition member is displaced, and deforms so that the partition member can be displaced even after the abutment.

4. 2. The shock absorber according to claim 1, wherein the valve closing portion is formed by an elastic member that is provided in a part of a member that forms the second passage, abuts against the partition member after the partition member is displaced, and deforms so that the partition member can be displaced even after the abutment.

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