JP7728221B2 - buffer - Google Patents

Description

The present invention relates to a shock absorber.

Some shock absorbers are equipped with a partition disc that has a valve member, a disc, to partition the passage (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-16288

In shock absorbers, there is a demand for improved durability of valve members.

Therefore, the present invention aims to provide a shock absorber that can improve the durability of the valve member.

In order to achieve the above object, one aspect of the present invention comprises a cylinder in which a working fluid is sealed, a piston slidably fitted within the cylinder and dividing the interior of the cylinder into two chambers, a piston rod connected to the piston and extending to the outside of the cylinder, a first passage that allows the working fluid to flow between the two chambers as the piston moves, a second passage that is provided in parallel with the first passage and allows the working fluid to flow into at least one of the two chambers as the piston moves, and a first damping mechanism that is provided in the first passage and generates a damping force. a valve member provided in the second passage that partitions the second passage and that, when a first displacement occurs due to the working fluid flowing in due to movement of the piston, allows at least a portion of the working fluid in the second passage to be discharged into the cylinder through a notch formed in an elastic body; and a restriction portion that, when the valve member undergoes a second displacement, closes the notch to form a closed pressure chamber between the second passage and the valve member, thereby restricting the movement of the working fluid in the pressure chamber, thereby generating a damping force.

This invention improves the durability of the valve member.

1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. 1 is a partial cross-sectional view showing the periphery of a piston of a shock absorber according to a first embodiment of the present invention. 1 is a half-side cross-sectional view showing a piston, a damping force mechanism, a frequency sensitive mechanism, etc. of a shock absorber according to a first embodiment of the present invention. FIG. 2 is a partially enlarged cross-sectional view showing a frequency sensitive mechanism of the shock absorber according to the first embodiment of the present invention. FIG. 2 is a plan view showing a partition member of the shock absorber according to the first embodiment of the present invention. 6 is a partially enlarged side view of the partition member of the shock absorber according to the first embodiment of the present invention, as viewed from the direction VI in FIG. 5. FIG. 2 is a partially enlarged cross-sectional view showing a frequency sensitive mechanism of the shock absorber according to the first embodiment of the present invention. FIG. 10 is a partially enlarged side view showing a partition member of a shock absorber according to a second embodiment of the present invention. FIG. 10 is a partially enlarged side view showing a partition member of a shock absorber according to a third embodiment of the present invention. FIG. 10 is a partially enlarged side view showing a partition member of a shock absorber according to a fourth embodiment of the present invention. FIG. 11 is a partially enlarged side view showing a partition member of a shock absorber according to a fifth embodiment of the present invention. FIG. 13 is a partially enlarged side view showing a partition member of a shock absorber according to a sixth embodiment of the present invention.

[First embodiment]
A shock absorber according to a first embodiment will be described below with reference to Figures 1 to 7. For ease of explanation, the upper side in Figures 1 to 3 will be referred to as "top" and the lower side in Figures 1 to 3 will be referred to as "bottom."

As shown in Figure 1, the shock absorber 1 of the first embodiment is a twin-cylinder hydraulic shock absorber. The shock absorber 1 is used in a vehicle suspension device. The shock absorber 1 has a cylinder 2 in which oil (not shown) is sealed as a working fluid. The cylinder 2 has an inner cylinder 3 and an outer cylinder 4. The inner cylinder 3 is cylindrical. The outer cylinder 4 is cylindrical with a bottom. The inner diameter of the outer cylinder 4 is larger than the outer diameter of the inner cylinder 3. The inner cylinder 3 is disposed radially inside the outer cylinder 4. The central axes of the inner cylinder 3 and the outer cylinder 4 coincide. A reservoir chamber 6 is formed between the inner cylinder 3 and the outer cylinder 4. The shock absorber 1 has a cover 5. The cover 5 covers the upper opening side of the outer cylinder 4.

The outer cylinder 4 has a body member 11 and a bottom member 12. The body member 11 is cylindrical. The bottom member 12 is cylindrical with a bottom. The bottom member 12 is fitted onto the lower side of the body member 11 and fixed to the body member 11 by welding. The bottom member 12 closes the lower part of the body member 11. A mounting eye 13 is fixed to the outside of the bottom member 12, opposite the body member 11 in the axial direction. The cover 5 is fitted onto the outer periphery of the body member 11, covering the opening at the top end of the body member 11.

The shock absorber 1 is equipped with a piston 18. The piston 18 is slidably fitted within the inner tube 3 of the cylinder 2. The piston 18 divides the inner tube 3 of the cylinder 2 into two chambers: an upper chamber 19 and a lower chamber 20. In the axial direction of the cylinder 2, the upper chamber 19 is located on the opposite side of the piston 18 from the bottom member 12. In the axial direction of the cylinder 2, the lower chamber 20 is located on the bottom member 12 side of the piston 18. Oil liquid is sealed within the upper chamber 19 and lower chamber 20 of the inner tube 3 as a working fluid. Oil liquid and gas are sealed within the reservoir chamber 6 between the inner tube 3 and the outer tube 4 as a working fluid.

The shock absorber 1 is equipped with a piston rod 21. One axial end of the piston rod 21 is disposed within the inner tube 3 of the cylinder 2. This end of the piston rod 21 is connected to the piston 18. The other axial end of the piston rod 21, opposite the one end, extends from the cylinder 2 to the outside. The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 and piston rod 21 move together. In the shock absorber 1, the stroke in which the piston rod 21 moves in a direction increasing the amount of protrusion from the cylinder 2 is the extension stroke, in which the overall length is extended. In the shock absorber 1, the stroke in which the piston rod 21 moves in a direction decreasing the amount of protrusion from the cylinder 2 is the compression stroke, in which the overall length is shortened. In the shock absorber 1, the piston 18 moves toward the upper chamber 19 during the extension stroke. In the shock absorber 1, the piston 18 moves toward the lower chamber 20 during the compression stroke.

Rod guides 22 are fitted to the upper openings of the inner cylinder 3 and the outer cylinder 4. A seal member 23 is fitted to the outer cylinder 4 above the rod guide 22. A friction member 24 is provided between the rod guide 22 and the seal member 23. The rod guide 22, seal member 23, and friction member 24 are all annular. The piston rod 21 is inserted through the rod guide 22, friction member 24, and seal member 23. The piston rod 21 slides axially relative to the rod guide 22, friction member 24, and seal member 23. The piston rod 21 extends from the inside of the cylinder 2 beyond the seal member 23 toward the outside of the cylinder 2.

The rod guide 22 restricts radial movement of the piston rod 21 relative to the inner and outer cylinders 3 and 4 of the cylinder 2. The piston rod 21 is fitted into the rod guide 22, and the piston 18 is fitted into the inner cylinder 3. This aligns the central axis of the piston rod 21 with the central axis of the cylinder 2. The rod guide 22 supports the piston rod 21 so that it can move in the axial direction of the piston rod 21. The outer periphery of the seal member 23 is in close contact with the inner periphery of the body member 11 of the outer cylinder 4. The inner periphery of the seal member 23 is in close contact with the outer periphery of the piston rod 21. The piston rod 21 moves in the axial direction of the seal member 23 while maintaining a close contact with the seal member 23. The seal member 23 prevents the oil in the inner cylinder 3 and the high-pressure gas and oil in the reservoir chamber 6 from leaking to the outside. The inner periphery of the friction member 24 contacts the outer periphery of the piston rod 21. The piston rod 21 moves relative to the friction member 24 in the axial direction of the friction member 24. The friction member 24 generates frictional resistance against the piston rod 21.

The rod guide 22 has a larger diameter at its outer periphery at the top than at the bottom. The smaller-diameter lower part of the rod guide 22 fits into the inner periphery of the upper end of the inner cylinder 3. The larger-diameter upper part of the rod guide 22 fits into the inner periphery of the upper part of the outer cylinder 4. A base valve 25 is installed on the bottom member 12 of the outer cylinder 4. The base valve 25 is positioned radially relative to the outer cylinder 4. The base valve 25 separates the lower chamber 20 and the reservoir chamber 6. The inner periphery of the lower end of the inner cylinder 3 fits into the base valve 25. Although not shown, a portion of the upper end of the outer cylinder 4 is crimped radially inward of the outer cylinder 4. The seal member 23 is fixed to the cylinder 2 by being sandwiched between this crimped portion and the rod guide 22.

The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28. The outer diameter of the mounting shaft portion 28 is smaller than that of the main shaft portion 27. The mounting shaft portion 28 is disposed within the cylinder 2. The piston 18 is attached to the mounting shaft portion 28. The main shaft portion 27 has a shaft step 29. The shaft step 29 is provided at the end of the main shaft portion 27 on the mounting shaft portion 28 side in the axial direction. The shaft step 29 widens in a direction perpendicular to the central axis of the piston rod 21. The piston rod 21 has a passage groove 30 formed on the outer periphery of the mounting shaft portion 28. The passage groove 30 extends in the axial direction of the mounting shaft portion 28. Multiple passage grooves 30 are formed at intervals around the circumferential direction of the mounting shaft portion 28. A male thread 31 is formed on the outer periphery of the mounting shaft portion 28 at the end opposite the main shaft portion 27 from the passage groove 30 in the axial direction of the mounting shaft portion 28.

The piston rod 21 is provided with an annular stopper member 32 and an annular buffer 33. Both the stopper member 32 and the buffer 33 are provided in the main shaft portion 27 between the piston 18 and the rod guide 22. The piston rod 21 is inserted into the inner periphery of the stopper member 32 and the buffer 33. The stopper member 32 is fixed to the main shaft portion 27 by crimping. The buffer 33 is located between the stopper member 32 and the rod guide 22.

The shock absorber 1 is connected to the vehicle body with the portion of the piston rod 21 that protrudes from the cylinder 2 positioned at the top. In this case, the shock absorber 1 is connected to the vehicle wheel side with the mounting eye 13 provided on the cylinder 2 side positioned at the bottom. The shock absorber 1 may also be connected to the vehicle body on the opposite side, with the cylinder 2 side connected to the vehicle body. In this case, the piston rod 21 of the shock absorber 1 is connected to the wheel side.

When a vehicle travels, the wheels vibrate relative to the vehicle body. This vibration causes the relative positions of the cylinder 2 and piston rod 21 in the shock absorber 1 to change. This change is suppressed by the fluid resistance of the flow paths provided in the shock absorber 1. As explained below, the fluid resistance of the flow paths provided in the shock absorber 1 is designed to vary depending on the speed and amplitude of the vibrations. The shock absorber 1 suppresses vibration, improving the ride comfort of the vehicle.

In addition to vibrations generated by the wheels relative to the vehicle body, in a vehicle, inertial and centrifugal forces generated in the vehicle body as the vehicle travels also act between the cylinder 2 and the piston rod 21. For example, centrifugal force is generated in the vehicle body when the direction of travel is changed by operating the steering wheel. A force based on this centrifugal force then acts between the cylinder 2 and the piston rod 21. As explained below, the shock absorber 1 has good characteristics against vibrations based on forces generated in the vehicle body as the vehicle travels. The shock absorber 1 provides the vehicle with high driving stability.

As shown in FIG. 2, the piston 18 has a piston body 35 and a sliding member 36. The piston body 35 is made of metal and has an annular shape. The piston 18 has the piston body 35 fitted onto the piston rod 21. The sliding member 36 is made of synthetic resin and has an annular shape. The sliding member 36 is integrally attached to the outer peripheral surface of the piston body 35. The piston 18 slides relative to the inner cylinder 3 with the sliding member 36 in contact with the inner cylinder 3.

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

The passage groove 38 is formed in the piston body 35 in an annular shape in the circumferential direction of the piston body 35. The passage groove 38 is formed at one end of the piston body 35 in the axial direction. All of the passage holes 37 open to the passage groove 38 at this one end in the axial direction of the piston body 35. The passage groove 40 is formed in the piston body 35 in an annular shape in the circumferential direction of the piston body 35. The passage groove 40 is formed at the other end of the piston body 35 opposite the passage groove 38 in the axial direction. All of the passage holes 39 open to the passage groove 40 at the end opposite the passage groove 38 in the axial direction of the piston body 35. The ends of the multiple passage holes 37 opposite the passage groove 38 in the axial direction of the piston body 35 open outward from the passage groove 40 in the radial direction of the piston body 35. The ends of the multiple passage holes 39 opposite the passage groove 40 in the axial direction of the piston body 35 open further outward than the passage groove 38 in the radial direction of the piston body 35. In the piston 18, the insides of the multiple passage holes 37 and the passage groove 38 form a passage 43 (first passage). In the piston 18, the insides of the multiple passage holes 39 and the passage groove 40 form a passage 44.

A damping force mechanism 41 (first damping force mechanism) is provided in the passage 43. The damping force mechanism 41 opens and closes the passage 43 to generate a damping force. The damping force mechanism 41 is located on the lower chamber 20 side, which is one end of the piston 18 in the axial direction, and is attached to the piston rod 21. As a result, the passage 43 serves as a passage through which oil flows from the upper chamber 19 to the lower chamber 20 as the piston 18 moves toward the upper chamber 19. In other words, the passage 43 allows oil to flow between the upper chamber 19 and the lower chamber 20 as the piston 18 moves. The passage 43 is an extension-side passage through which oil flows as a working fluid from the upper chamber 19 to the lower chamber 20 during the extension stroke. The damping force mechanism 41 is an extension-side damping force mechanism that generates a damping force by suppressing the flow of oil from the passage 43 to the lower chamber 20 during the extension stroke.

A damping force mechanism 42 is provided in the passage 44. The damping force mechanism 42 opens and closes the passage 44 to generate a damping force. The damping force mechanism 42 is located on the upper chamber 19 side, which is the other axial end of the piston 18, and is attached to the piston rod 21. As a result, the passage 44 becomes a passage through which oil flows from the lower chamber 20 to the upper chamber 19 as the piston 18 moves toward the lower chamber 20. In other words, the passage 44 allows oil as a working fluid to flow between the lower chamber 20 and the upper chamber 19 as the piston 18 moves. The passage 44 is a compression-side passage through which oil flows from the lower chamber 20 to the upper chamber 19 during the compression stroke. The damping force mechanism 42 is a compression-side damping force mechanism that generates a damping force by suppressing the flow of oil from the passage 44 to the upper chamber 19 during the compression stroke.

The piston body 35 has an insertion hole 45 formed in its radial center, penetrating the piston body 35 in the axial direction. The mounting shaft portion 28 of the piston rod 21 is inserted through the insertion hole 45. The insertion hole 45 has a small diameter hole portion 46 and a large diameter hole portion 47. The large diameter hole portion 47 has a larger diameter than the small diameter hole portion 46. The mounting shaft portion 28 of the piston rod 21 is fitted into the small diameter hole portion 46 of the piston body 35. In the axial direction of the insertion hole 45, the large diameter hole portion 47 is located closer to the lower chamber 20 than the small diameter hole portion 46.

A valve seat portion 48 is formed at the end of the piston body 35 on the axial side of the lower chamber 20. The valve seat portion 48 is annular. The valve seat portion 48 is located radially outward of the opening of the passage groove 38 on the lower chamber 20 side of the piston body 35. The valve seat portion 48 constitutes a part of the damping force mechanism 41.
A valve seat portion 49 is formed at the end of the piston body 35 on the axial side of the upper chamber 19. The valve seat portion 49 is annular. The valve seat portion 49 is located radially outward of the opening of the passage groove 40 on the upper chamber 19 side of the piston body 35. The valve seat portion 49 constitutes a part of the damping force mechanism 42.
In the piston body 35, openings of all the passage holes 39 on the side facing the lower chamber 20 are arranged on the radial side of the piston body 35 opposite the passage groove 38 of the valve seat portion 48. In the piston body 35, openings of all the passage holes 37 on the side facing the upper chamber 19 are arranged on the radial side of the piston body 35 opposite the passage groove 40 of the valve seat portion 49.

As shown in FIG. 3, on the valve seat portion 48 side of the piston 18 in the axial direction, there are provided, in order from the piston 18 side in the axial direction of the piston 18, one disk 51, one damping valve 52, one disk 53, one disk 54, one pilot case 55, one disk 56, one disk 57, multiple disks 58 (specifically, three), one disk 59, and one disk 60. The disks 51, 53, 54, 56-60, and the pilot case 55 are all made of metal. The disks 51, 53, 54, 56-60 are all circular, flat plates with holes of a fixed thickness. The mounting shaft portion 28 of the piston rod 21 is fitted inside each of the disks 51, 53, 54, 56-60. The damping valve 52 and the pilot case 55 are all annular. The mounting shaft portion 28 of the piston rod 21 fits inside both the damping valve 52 and the pilot case 55.

The pilot case 55 is cylindrical and has a bottom. A through-hole 70 is formed in the radial center of the pilot case 55. The through-hole 70 passes through the pilot case 55 in the axial direction. The pilot case 55 has a bottom 71, an inner cylindrical portion 72, an outer cylindrical portion 73, an inner seat portion 74, and a valve seat portion 75.

The through hole 70 has a large diameter hole portion 76 and a small diameter hole portion 77. The large diameter hole portion 76 has a larger diameter than the small diameter hole portion 77. The large diameter hole portion 76 is disposed on the piston 18 side of the through hole 70 in the axial direction. The small diameter hole portion 77 is disposed on the opposite side of the large diameter hole portion 76 from the piston 18 in the axial direction of the through hole 70.
The bottom portion 71 is a disk-shaped portion having holes. A passage hole 78 is formed in the bottom portion 71 radially outward of the through-hole 70, penetrating the bottom portion 71 in the axial direction of the bottom portion 71.
The inner cylindrical portion 72 is cylindrical and protrudes from the inner peripheral edge of the bottom portion 71 toward the piston 18 along the axial direction of the bottom portion 71. The inner cylindrical portion 72 is located radially inward of the passage hole 78 of the bottom portion 71.
The outer cylindrical portion 73 is cylindrical and protrudes from the outer peripheral edge of the bottom portion 71 along the axial direction of the bottom portion 71 on the same side as the inner cylindrical portion 72. The outer cylindrical portion 73 is provided outward of the passage hole 78 in the radial direction of the bottom portion 71. 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 portion 71.

The inner seat portion 74 is annular and protrudes from the inner peripheral edge of the bottom portion 71 in the axial direction opposite to the inner cylindrical portion 72 .
The valve seat portion 75 is annular and has a larger diameter than the inner seat portion 74. The valve seat portion 75 protrudes from the bottom portion 71 along the axial direction of the bottom portion 71 on the same side as the inner seat portion 74, radially outward of the inner seat portion 74. The passage hole 78 is disposed between the inner seat portion 74 and the valve seat portion 75 in the radial direction of the bottom portion 71.

The disc 51 has an outer diameter smaller than the inner diameter of the tip surface of the valve seat portion 48. A notch 81 is formed in the disc 51. The notch 81 extends radially outward from the inner peripheral edge of the disc 51 that fits onto the mounting shaft portion 28, and into the passage groove 38. A restrictor 82 is formed within the notch 81. The restrictor 82 is constantly connected to the passage 43 of the piston 18. The passage within the large diameter hole 47 of the piston 18 is constantly connected to the passage within the passage groove 30 of the piston rod 21. The passage within the large diameter hole 47 and the passage within the passage groove 30 form a rod chamber 83. The restrictor 82 within the notch 81 of the disc 51 is constantly connected to the rod chamber 83. The restrictor 82 constantly connects the passage 43 and the rod chamber 83.

The damping valve 52 comprises a disk 85 and a seal member 86 .
The disk 85 is made of metal and has a circular, flat plate shape with holes. The disk 85 has an outer diameter larger than the outer diameter of the tip end surface of the valve seat portion 48. The mounting shaft portion 28 of the piston rod 21 is fitted inside the disk 85. The disk 85 abuts against the valve seat portion 48 of the piston 18, and opens and closes the opening of the passage 43 formed in the piston 18 by moving away from and abutting against the valve seat portion 48. The passage between the spaced-apart disk 85 and the valve seat portion 48 also constitutes the passage 43.
The seal member 86 is made of rubber and is bonded to the disk 85. The seal member 86 is fixed to the outer periphery of the disk 85 and has an annular shape. The seal member 86 is fitted liquid-tightly around the entire inner periphery of the outer cylindrical portion 73 of the pilot case 55. The seal member 86 is axially slidable relative to the inner periphery of the outer cylindrical portion 73. The seal member 86 constantly seals the gap between the damping valve 52 and the outer cylindrical portion 73.

The outer diameter of disc 53 is smaller than the minimum inner diameter of seal member 86. The outer diameter of disc 54 is larger than the outer diameter of disc 53 and smaller than the minimum inner diameter of seal member 86. A notch 91 is formed in disc 54. The notch 91 extends radially outward from the inner peripheral edge of disc 54 that fits onto the mounting shaft portion 28, to a position outside disc 53. A restrictor 92 is formed within notch 91. The restrictor 92 is constantly in communication with the passage in passage groove 30 of piston rod 21 and the passage in large diameter hole portion 76 of pilot case 55.

Disc 56 has an outer diameter smaller than the inner diameter of the tip surface of valve seat portion 75 of pilot case 55. Disk 57 has an outer diameter larger than the outer diameter of the tip surface of valve seat portion 75. Disk 57 is able to seat on valve seat portion 75. Disk 57 has a notch 93 formed on its outer periphery. Notch 93 extends radially across valve seat portion 75. Disk 58 has an outer diameter equal to the outer diameter of disk 57. Disk 59 has an outer diameter smaller than the outer diameter of disk 58. Disk 60 has an outer diameter larger than the outer diameter of disk 59 but smaller than the outer diameter of disk 58. Disks 57 and 58 form a disk valve 99. Disk valve 99 is able to seat and remove from valve seat portion 75.

A backpressure chamber 100 is formed between the bottom 71, inner cylindrical portion 72, and outer cylindrical portion 73 of the pilot case 55 and the damping valve 52 and discs 53 and 54; between the bottom 71, inner seat portion 74, and valve seat portion 75 of the pilot case 55 and the disc 56 and disc valve 99; and within the passage hole 78 of the pilot case 55. The backpressure chamber 100 applies pressure to the damping valve 52 in the direction of the piston 18. In other words, the backpressure chamber 100 applies internal pressure to the damping valve 52 in the valve closing direction, in which the damping valve 52 seats on the valve seat portion 48. The damping valve 52 is a pilot-type damping valve having a backpressure chamber 100. The damping valve 52 and backpressure chamber 100 constitute part of the damping force mechanism 41. The backpressure chamber 100 is constantly in communication with the rod chamber 83 via a restrictor 92 in the notch 91 of the disc 54. The passage within the large diameter hole 76 of the pilot case 55 is constantly in communication with the passage within the passage groove 30 of the piston rod 21. The passage within the large diameter hole 76 of the pilot case 55 also constitutes the rod chamber 83.

The restriction 82 in the notch 81 of the disc 51, the rod chamber 83, and the restriction 92 in the notch 91 of the disc 54 form a passage 102 that constantly connects the passage 43 of the piston 18 to the back pressure chamber 100, introducing hydraulic fluid from the passage 43 to the back pressure chamber 100. When the disc 85 lifts off the valve seat 48 of the piston 18 and opens, the damping valve 52 allows hydraulic fluid from the passage 43 to flow into the lower chamber 20 through the gap between the piston 18 and the outer cylindrical portion 73 of the pilot case 55. At that time, the damping valve 52 suppresses the flow of hydraulic fluid between the valve seat 48. The extension damping force mechanism 41 introduces a portion of the hydraulic fluid flow into the back pressure chamber 100 via the passage 102, and controls the opening of the damping valve 52 using the pressure in the back pressure chamber 100.

When the disc valve 99 lifts off the valve seat 75, it connects the back pressure chamber 100 to the lower chamber 20. At that time, the disc valve 99 restricts the flow of oil between it and the valve seat 75. The passage within the notch 93 of the disc valve 99 forms a fixed orifice 105 that connects the back pressure chamber 100 to the lower chamber 20 even when the disc valve 99 is in contact with the valve seat 75. The disc 60 abuts against the disc valve 99 when it deforms in the opening direction, restricting the disc valve 99 from deforming beyond the specified limit.

The disc valve 99 and valve seat 75 constitute the damping force mechanism 110. When the disc valve 99 leaves the valve seat 75, the damping force mechanism 110 connects the back pressure chamber 100 and the lower chamber 20. At this time, the damping force mechanism 110 generates a damping force by suppressing the flow of oil between the back pressure chamber 100 and the lower chamber 20. The damping force mechanism 110 is located between the back pressure chamber 100 and the lower chamber 20 and generates a damping force through the flow of oil. During the extension stroke, the damping force mechanism 110 flows oil from the upper chamber 19 to the lower chamber 20 via passage 43, passage 102, and the back pressure chamber 100. The damping force mechanism 110 is an extension-side damping force mechanism that generates a damping force by suppressing the flow of oil from the back pressure chamber 100 to the lower chamber 20 during the extension stroke.

As shown in FIG. 2, on the valve seat portion 49 side of the piston 18 in the axial direction, there are provided, in order from the piston 18 side in the axial direction of the piston 18, one disk 111, one disk 112, multiple (specifically, three) disks 113, multiple (specifically, two) disks 114, one disk 115, one disk 116, and one annular member 117. The disks 111-116 and the annular member 117 are all made of metal. The disks 111-116 and the annular member 117 are all perforated circular flat plates of a fixed thickness. The mounting shaft portion 28 of the piston rod 21 is fitted inside the disks 111-116 and the annular member 117.

The disk 111 has an outer diameter smaller than the inner diameter of the leading end surface of the valve seat portion 49 of the piston 18. The disk 112 has an outer diameter slightly larger than the outer diameter of the leading end surface of the valve seat portion 49 of the piston 18. The disk 112 is capable of being seated on the valve seat portion 49. A notch 121 is formed on the outer periphery of the disk 112. The notch 121 extends radially across the valve seat portion 49.

The multiple discs 113 have an outer diameter equal to that of disc 112. The multiple discs 114 have an outer diameter smaller than that of disc 113. Disc 115 has an outer diameter smaller than that of disc 114. Disc 116 has an outer diameter larger than that of disc 114 and smaller than that of disc 113. Annular member 117 has an outer diameter smaller than that of disc 116 and larger than that of disc 114. Annular member 117 is thicker and more rigid than discs 111 to 116. This annular member 117 abuts against the shaft step 29 of the piston rod 21.

The discs 112 to 114 constitute a disc valve 122. The disc valve 122 is capable of being seated on and removed from the valve seat portion 49. When the disc valve 122 is released from the valve seat portion 49, it can open the passage 44 to the upper chamber 19. At that time, the disc valve 122 suppresses the flow of oil from the lower chamber 20 to the upper chamber 19 via the passage 44. The disc valve 122 and the valve seat portion 49 constitute the compression-side damping force mechanism 42. The notch 121 of the disc 112 constitutes a fixed orifice 123. The fixed orifice 123 allows communication between the lower chamber 20 and the upper chamber 19 even when the disc 112 is in contact with the valve seat portion 49. The fixed orifice 123 also constitutes the damping force mechanism 42.
When the disc valve 122 deforms in the opening direction, the disc 116 abuts against the disc valve 122 to prevent the disc valve 122 from deforming in the opening direction beyond a specified limit.

3, a frequency sensitive mechanism 130 (second damping force mechanism) is provided on the axial side of the disk 60 opposite to the disk 59. The frequency sensitive mechanism 130 varies the damping force in accordance with the frequency of the axial movement of the piston 18 (hereinafter referred to as the piston frequency).
Frequency sensitive mechanism 130 has one housing main body 131 closest to disk 60 in the axial direction. Frequency sensitive mechanism 130 also has, in order from housing main body 131, one disk 132, one disk 133, and one disk 134 on the inner circumferential side of housing main body 131 opposite disk 60 in the axial direction. Frequency sensitive mechanism 130 also has one partition member 135 radially outward of disks 133 and 134, which are on the opposite side of disk 60 in the axial direction of housing main body 131. Frequency sensitive mechanism 130 also has, as shown in FIG. 4 , multiple, specifically three, disks 141 on the axial opposite side of disk 134 and partition member 135 from disk 132, in order from disk 134 and partition member 135. An annular member 144 is provided on the opposite side of the disk 141 from the disk 140 in the axial direction.

The housing main body 131, discs 132-134, 136-141, and annular member 144 are all made of metal. The discs 132-134, 136-141, and annular member 144 are all perforated circular flat plates of a uniform thickness. The discs 133, 134, 136-141, and annular member 144 have a uniform radial width around their entire circumference. The discs 132-134, 136-141 are all formed by punching out from a single thin plate. The mounting shaft 28 of the piston rod 21 is fitted to the inside of the discs 132-134, 136-141, housing main body 131, and annular member 144. The mounting shaft 28 of the piston rod 21 and discs 133 and 134 are inserted into the inner periphery of the partition member 135. Disks 132-134, 136-141 and housing main body 131 form housing 145 of frequency sensitive mechanism 130.

As shown in FIG. 3, the housing body 131 is cylindrical and has a bottom.
A through hole 155 is formed in the radial center of the housing body 131, penetrating the housing body 131 in the axial direction. The through hole 155 has a large diameter hole portion 156 and a small diameter hole portion 157. The large diameter hole portion 156 has a larger diameter than the small diameter hole portion 157. The large diameter hole portion 156 is located on the opposite side of the through hole 155 from the disc 60 in the axial direction. The small diameter hole portion 157 is located closer to the disc 60 than the large diameter hole portion 156 in the axial direction of the through hole 155. The passage within the large diameter hole portion 156 of the housing body 131 is constantly in communication with the passage within the passage groove 30 of the piston rod 21. The passage within the large diameter hole portion 156 of the housing body 131 also constitutes the rod chamber 83.

The housing body 131 has a bottom portion 150 , a protruding portion 151 on one side, a protruding portion 152 on the other side, a cylindrical portion 153 , and a seat portion 154 .
The bottom 150 is a perforated disk.
The one-side protrusion 151 is annular and protrudes from the inner peripheral edge of the bottom portion 150 in the axial direction of the bottom portion 150 toward the opposite side from the disk 60 .
The other-side protrusion 152 is annular and protrudes from the inner peripheral edge of the bottom portion 150 in the axial direction of the bottom portion 150 to the opposite side from the one-side protrusion 151.
The cylindrical portion 153 has a cylindrical shape and extends from the outer peripheral edge of the bottom portion 150 along the axial direction of the bottom portion 150 on the same side as the one-side protruding portion 151.
The seat portion 154 is annular in shape. The seat portion 154 protrudes from a position between the one-side protrusion 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 one-side protrusion 151 and the cylindrical portion 153. A notch 158 that penetrates the seat portion 154 in the radial direction is formed at the end of the seat portion 154 on the protruding tip side.

As shown in Figure 4, the disk 132 has an outer diameter that is larger than the outer diameter of the tip surface of the one-side protrusion 151 and smaller than the inner diameter of the tip surface of the seat portion 154. A notch 161 is formed in the disk 132. The notch 161 extends radially outward from the inner peripheral edge of the disk 132 that fits onto the mounting shaft portion 28, to a position outside the tip surface of the one-side protrusion 151. A throttle 162 is formed within the notch 161. The throttle 162 is constantly in communication with a passage within the large-diameter hole 156 of the housing main body 131. Therefore, the throttle 162 is constantly in communication with the rod chamber 83.
The disk 133 has an outer diameter smaller than the outer diameter of the disk 132. The notch 161 of the disk 132 extends radially outward of the disk 132 beyond the disk 133. The disk 133 has a greater axial thickness than the disk 132.
The disk 134 has an outer diameter smaller than that of the disk 133. The disk 134 has a smaller axial thickness than the disk 133.

The partition member 135 consists of a valve disc 171 (valve member) and an elastic body 172. The partition member 135 is disposed within the cylindrical portion 153 of the housing main body 131. The partition member 135 is disposed radially between the cylindrical portion 153 and the discs 133 and 134.

The valve disc 171 is made of metal. It is a circular, flat plate with holes of a constant thickness. It has a constant radial width and is annular. The mounting shaft portion 28 of the piston rod 21 is inserted into the inner periphery of the valve disc 171. The valve disc 171 is disposed within the cylindrical portion 153 of the housing main body 131. The valve disc 171 is elastically deformable, i.e., flexible. The inner diameter of the valve disc 171 is larger than the outer diameter of the disc 133. The valve disc 171 has an inner diameter that allows the discs 133 and 134 to be positioned inside with a radial gap. The axial thickness of the valve disc 171 is thinner than the axial thickness of two discs 133 and 134. The outer diameter of the valve disc 171 is larger than the outer diameter of the tip surface of the seat portion 154 of the housing main body 131.

The elastic body 172 is made of a rubber material and has an annular shape. The elastic body 172 is adhered to the outer periphery of the valve disc 171. The elastic body 172 is baked onto the valve disc 171 and is integral with the valve disc 171. The elastic body 172 has a sealing portion 175 and a contact portion 176.

The seal portion 175 is annular and is fixed around the entire outer periphery of the valve disc 171. The seal portion 175 protrudes from the valve disc 171 toward the bottom 150 of the housing main body 131 in the axial direction of the partition member 135. The seal portion 175 has an annular protrusion 177 that protrudes radially outward from the outer periphery at a midpoint in the axial direction.

The abutment portion 176 is provided on the opposite side of the partition member 135 from the seal portion 175 of the valve disc 171 in the axial direction. As shown in FIG. 5, the abutment portion 176 is annular and is fixed to the outer periphery of the valve disc 171 along its entire circumference. As shown in FIG. 4, the abutment portion 176 protrudes from the valve disc 171 on the opposite side of the bottom portion 150 in the axial direction of the partition member 135. The abutment portion 176 of the elastic body 172 is expandable and contractible in the axial direction of the partition member 135.

A notch 178 is formed at the tip of the abutment portion 176 on the side opposite the valve disc 171 in the axial direction of the partition member 135. The notch 178 is groove-shaped and recessed toward the valve disc 171 from the tip of the abutment portion 176 on the side opposite the valve disc 171 in the axial direction of the partition member 135. The notch 178 penetrates the abutment portion 176 in the radial direction of the abutment portion 176. As shown in Figure 5, multiple notches 178 of the same shape are provided in the abutment portion 176 at equal intervals around the circumferential direction of the abutment portion 176, specifically three notches 178.

As shown in Figure 6, the cutout portion 178 has a bottom surface portion 179 and a pair of wall surface portions 180. The bottom surface portion 179 is flat and extends perpendicular to the axial direction of the partition member 135. The pair of wall surface portions 180 are inclined at the same angle relative to the bottom surface portion 179. The further the pair of wall surface portions 180 are from the bottom surface portion 179 in the axial direction of the partition member 135, the wider the distance between them in the circumferential direction of the partition member 135.

As shown in Figure 4, the abutment portion 176 has a main body portion 181 that is adhered to the valve disc 171 by forming a notch portion 178, and a protrusion portion 182 that protrudes from the main body portion 181 on the opposite side of the valve disc 171 in the axial direction of the partition member 135.
The main body 181 is annular. A bottom surface 179 of the notch 178 is formed in the main body 181.

As shown in FIG. 5, the protrusions 182 are formed between adjacent notches 178 in the circumferential direction of the partition member 135. The abutment portion 176 has the same shaped protrusions 182 provided at equal intervals in the circumferential direction of the partition member 135, and the same number as the notches 178. The protrusions 182 are arc-shaped when viewed in the axial direction of the partition member 135. The length of the protrusions 182 in the circumferential direction of the partition member 135 is longer than the length of the notches 178 in the circumferential direction of the partition member 135. As shown in FIG. 6, the wall surface portion 180 of the notch 178 is formed in the protrusions 182.

As shown in Figure 4, an annular gap is provided between the valve disc 171 and the cylindrical portion 153 of the housing main body 131. The elastic body 172 secures the seal portion 175 and the abutment portion 176 to both sides of the valve disc 171 through this gap.

The annular protrusion 177 of the seal portion 175 of the elastic body 172 is fitted liquid-tightly around the entire inner circumference of the cylindrical portion 153 of the housing main body 131. The seal portion 175 is able to slide relative to the cylindrical portion 153 in the axial direction of the cylindrical portion 153. The seal portion 175 of the elastic body 172 constantly seals the gap between the partition member 135 and the cylindrical portion 153. The minimum inner diameter of the seal portion 175 is larger than the outer diameter of the tip surface of the seat portion 154. The valve disc 171 of the partition member 135 is able to seat on the seat portion 154 of the housing main body 131.

Disc 136 has an outer diameter larger than the inner diameter of valve disc 171. Disk 136 has a thinner axial thickness than disc 134. Disk 136 has a thinner axial thickness than valve disc 171. Disk 136 abuts against the inner periphery of valve disc 171 over the entire circumference, thereby closing the gap between disc 136 and valve disc 171. The inner periphery of partition member 135 is positioned axially between disc 132 and disc 136 and is supported by abutting disc 136. The inner periphery of partition member 135 is movable between disc 132 and disc 136 within the axial length of the two discs 133 and 134. The partition member 135 is centered relative to the housing 145 by the seal portion 175 contacting the cylindrical portion 153 over the entire circumference. The inner circumferential side of the partition member 135, that is, the inner circumferential side of the valve disc 171, is not clamped from either side, but is supported on only one side by the disc 136. The radially outer side of the valve disc 171 of the partition member 135 is not clamped from either side, but is supported on only one side by the seat portion 154. Therefore, the partition member 135 is not clamped in the axial direction, and has a simply supported structure in which one side of the valve disc 171 is supported by the disc 136 and the other side of the valve disc 171 is supported by the seat portion 154. The partition member 135 is annular overall and is elastically deformable, i.e., flexible.

The disk 137 has an outer diameter that is larger than the outer diameter of the disk 136 and smaller than the minimum inner diameter of the abutting portion 176. The disk 137 has a smaller axial thickness than the disk 136.
The disk 138 has an outer diameter smaller than that of the disk 137. The disk 138 has a greater axial thickness than the disk 137.

The disk 139 has an outer diameter smaller than that of the disk 138. The disk 139 has an axial thickness greater than that of each of the disks 136 to 138. The disk 139 can be formed by punching out from a single thin plate, or by cutting out.
The outer diameter of disk 140 is larger than the outer diameter of disk 139 and is equal to the outer diameter of disk 137. Disk 140 has a greater axial thickness than disk 139. Disk 140 can be formed by punching out from a single thin plate, or by cutting.
The outer diameter of disk 141 is larger than the outer diameter of disk 140. Disk 141 has a greater axial thickness than each of disks 136 to 138. The outer diameter of disk 141 is smaller than the inner diameter of cylindrical portion 153. Of the multiple disks 141, the disk 141 closest to disk 140 always abuts against protruding portion 182 of abutting portion 176 of partition member 135.

Support member 185 is formed by stacking discs 136-138, which are all plate-shaped members. Of discs 136-138, discs 137 and 138 have a smaller outer diameter on the axial side opposite valve disc 171 than disc 137 on the axial side of valve disc 171. Of discs 137 and 138, disc 138 on the axial side opposite valve disc 171 has a greater thickness than disc 137 on the axial side of valve disc 171. Support member 185 supports the inner periphery of valve disc 171 of partition member 135. The inner periphery of valve disc 171 of partition member 135 is not clamped from both axial sides, and only one axial side is supported by disc 136 of support member 185.

Multiple discs 141 are stacked to form a stopper member 188 (limiting portion). The stopper member 188 limits movement of the partition member 135 in the axial direction of the housing main body 131 in the direction opposite to the seat portion 154.

When the valve disc 171 is displaced axially toward the stopper member 188, the partition member 135 elastically deforms the abutment portion 176 of the elastic body 172. Even when a pressure load is generated, in the first displacement where the valve disc 171 is displaced toward the stopper member 188 by a predetermined amount or less, the partition member 135 elastically deforms mainly at the protrusion 182 of the abutment portion 176, but the notch 178 is not blocked by the stopper member 188. On the other hand, in the second displacement where the pressure load increases and the valve disc 171 is displaced toward the stopper member 188 by an amount greater than the predetermined amount, the partition member 135 elastically deforms mainly at the protrusion 182 of the abutment portion 176, and the notch 178 is blocked by the stopper member 188, as shown in FIG. 7 . In other words, the stopper member 188 does not close the notch 178 when the valve disc 171 is displaced toward the stopper member 188 by a first displacement amount equal to or less than a predetermined value. On the other hand, the stopper member 188 closes the notch 178 of the abutment portion 176 when the valve disc 171 is displaced toward the stopper member 188 by a second displacement amount equal to or greater than a predetermined value. The abutment portion 176 of the elastic body 172 and the disc 141 of the stopper member 188 are always in contact with each other.

As shown in Figure 4, a communication passage 195 is formed radially between the stopper member 188 and the cylindrical portion 153 of the housing main body 131. The communication passage 195 is constantly in communication with the lower chamber 20. The communication passage 195 is located radially outward of the contact portion 176 of the elastic body 172 that contacts the stopper member 188.

The seal portion 175 of the partition member 135 has its annular protrusion 177 in contact with the inner surface of the cylindrical portion 153 of the housing main body 131 over the entire circumference. As a result, the seal portion 175 seals the gap between the partition member 135 and the cylindrical portion 153. In other words, the partition member 135 is a packing valve. The seal portion 175 constantly seals the gap between the partition member 135 and the cylindrical portion 153, even if the partition member 135 deforms within the allowable range within the housing 145. The partition member 135 is centered relative to the housing 145 as the seal portion 175 contacts the cylindrical portion 153 over the entire circumference. The partition member 135 closes the gap with the disk 136 as the valve disk 171 contacts the disk 136 over the entire circumference.

The seat portion 154 of the housing main body 131 supports the valve disc 171 of the partition member 135 from one axial side. The support member 185 supports the valve disc 171 from the other axial side, with its disc 136 supporting the valve disc 171 on the inner side of the seat portion 154. The shortest axial distance between the seat portion 154 and the disc 136 is smaller than the axial thickness of the valve disc 171. Therefore, the valve disc 171 is pressed against the seat portion 154 and disc 136 by its own elastic force over its entire circumference while being elastically deformed in a slightly tapered shape.

The partition member 135 divides the interior of the housing 145 into a variable chamber 191 and a variable chamber 192. The variable chamber 191 is located between the bottom 150 side of the housing main body 131 and the partition member 135. The variable chamber 192 is located between the partition member 135 and the stopper member 188. The volumes of the variable chambers 191 and 192 are both variable, and the volumes change as the partition member 135 deforms. The variable chambers 191 and 192 form a housing internal chamber 198 located within the housing 145. The partition member 135 is located in the housing internal chamber 198.

The variable chamber 191 is constantly connected to the rod chamber 83 via the orifice 162 in the notch 161 of the disk 132. Therefore, the variable chamber 191 is constantly connected to the upper chamber 19 via the orifice 162 in the disk 132, the rod chamber 83, the orifice 82 in the disk 51 shown in Figure 3, and the passage 43. The variable chamber 191 is also constantly connected to the back pressure chamber 100 via the orifice 162 in the disk 132, the rod chamber 83, and the orifice 92 in the disk 54.

A notch 158 is provided in the seat portion 154 of the housing main body 131. This ensures that the inside and outside of the variable chamber 191 are always in communication with each other in the radial direction relative to the seat portion 154.

The variable chamber 192 has an inner chamber 196 (pressure chamber) located radially inward of the contact portion 176, and an outer chamber 197 located radially outward of the contact portion 176. The outer chamber 197 is constantly connected to the lower chamber 20 via a communication passage 195.

As described above, the partition member 135 has multiple cutouts 178 arranged circumferentially at intervals in the abutment portion 176. This allows communication between the inner chamber 196 and outer chamber 197 of the variable chamber 192 via the passage within the cutouts 178. The inner chamber 196 and outer chamber 197 are able to communicate via the passage within the cutouts 178 when the displacement of the valve disc 171 of the partition member 135 is the first displacement described above. On the other hand, when the displacement of the valve disc 171 of the partition member 135 is the second displacement described above, which is greater than the first displacement, the passage within the cutouts 178 is blocked, and communication between the inner chamber 196 and outer chamber 197 is cut off. In other words, when the valve disc 171 is in the second displacement state, the inner chamber 196 on one side of the partition member 135 is blocked, and further displacement toward the inner chamber 196 is restricted, resulting in a hydraulically locked state.

During the extension stroke, oil from the upper chamber 19 (see Figure 3) is introduced into the variable chamber 191 via the passage 43, the orifice 82 in the disc 51, the rod chamber 83, and the orifice 162 in the disc 132. The valve disc 171 of the partition member 135 then deforms tapered, with the contact point between the support member 185 and the disc 136 (see Figure 4) as the fulcrum, moving its outer periphery away from the seat portion 154 in the axial direction of the seat portion 154. At this time, the valve disc 171 compresses and deforms, primarily the protruding portion 182, of the abutment portion 176 that abuts against the stopper member 188 of the partition member 135. This deformation of the valve disc 171 increases the volume of the variable chamber 191.

At this time, the support member 185 supporting the valve disc 171 applies resistance to this deformation of the valve disc 171. When the valve disc 171 deforms in this manner, the volume of the variable chamber 192 decreases. If the notch 178 is not blocked at this time, the oil in the variable chamber 192 flows into the lower chamber 20 via the communication passage 195.

In the initial stage of deformation toward the stopper member 188 , the valve disc 171 itself deforms, and compresses and deforms mainly the protruding portion 182 of the abutting portion 176 that abuts against the disc 141 of the stopper member 188 .
As the deformation of the valve disc 171 toward the stopper member 188 progresses further, the valve disc 171 itself deforms further and further compresses and deforms, mainly the protruding portion 182 of the abutment portion 176. At the same time, the valve disc 171 abuts against the outer periphery of the disc 137 of the support member 185, elastically deforming the outer periphery of the disc 137 in a tapered shape toward the stopper member 188.

As the deformation of the valve disc 171 toward the stopper member 188 progresses further, the valve disc 171 itself deforms further and further compresses and deforms, primarily the protruding portion 182 of the abutment portion 176. At the same time, the valve disc 171 further deforms the outer periphery of the disc 137 of the support member 185 in a tapered shape toward the stopper member 188. At the same time, the valve disc 171 elastically deforms the outer periphery of the disc 138, via the disc 137, in a tapered shape toward the stopper member 188.

The passage 43, the throttle 82, the rod chamber 83, the throttle 162, the housing inner chamber 198, and the communication passage 195 shown in FIG. 3 constitute a passage 201 (second passage). A portion of the passage 201 is arranged in parallel with the passage 43. The entire passage 201 is arranged in parallel with the passage 44. A flexible plate-shaped partition member 135 including the valve disc 171 is provided in the passage 201 to partition the passage 201. The passage 201 can communicate between the upper chamber 19 and the lower chamber 20. The passage 201 constantly connects the passage 43, the throttle 82, the rod chamber 83, the throttle 162, and the variable chamber 191 to the upper chamber 19. The passage 201 constantly connects the outer chamber 197 of the variable chamber 192 and the communication passage 195 to the lower chamber 20. The passage 201 allows the inner chamber 196 of the variable chamber 192 to communicate with the lower chamber 20.

The passage 201 is arranged so that oil can flow from the upper chamber 19, which is one of the upper and lower chambers 19 and 20 in the cylinder 2, between the passage 43, the throttle 82, the rod chamber 83, the throttle 162, and the variable chamber 191, as the piston 18 moves during the extension stroke. The passage 201 is arranged so that oil can flow from the lower chamber 20, which is one of the upper and lower chambers 19 and 20 in the cylinder 2, between the communication passage 195 and the variable chamber 192, as the piston 18 moves during the compression stroke. Here, the passage 201 may be arranged so that oil can flow only from the upper chamber 19, which is one of the upper and lower chambers 19 and 20. In other words, the passage 201 only needs to be arranged so that oil can flow from at least one of the upper chamber 19 and the lower chamber 20.

The inner circumferential side of the valve disc 171 of the partition member 135 is movable between disc 132 and disc 136. When the inner circumferential side of the valve disc 171 is in contact with disc 136 over the entire circumference, the partition member 135 blocks the flow of oil between the variable chambers 191 and 192. When the inner circumferential side of the valve disc 171 is separated from disc 136, the partition member 135 allows the flow of oil between the variable chambers 192 and 191. The inner circumferential side of the valve disc 171 and disc 136 form a check valve 205. The check valve 205 is provided in the passage 201. The check valve 205 restricts the flow of oil from the variable chamber 191 to the variable chamber 192, while allowing the flow of oil from the variable chamber 192 to the variable chamber 191. The check valve 205 blocks communication with the passage 201 during the extension stroke, when the pressure in the upper chamber 19 becomes higher than the pressure in the lower chamber 20. The check valve 205 opens the passage 201 during the compression stroke, when the pressure in the lower chamber 20 becomes higher than the pressure in the upper chamber 19.

The check valve 205 is a free valve in which the entire partition member 135, which serves as its valve body, is movable axially without being clamped. The partition member 135 may be configured so that the entire inner circumference of its valve disc 171 is always in contact with the disc 136, regardless of the pressure state of the variable chambers 191 and 192. In other words, the valve disc 171 of the partition member 135 may always block communication between the variable chambers 191 and 192. In other words, it is sufficient for the valve disc 171 of the partition member 135 to block the flow of oil in at least one direction through the passage 201.

The frequency sensitive mechanism 130 is provided in the passage 201 and generates a damping force during the extension stroke. The frequency sensitive mechanism 130 has a partition member 135 that partitions the passage 201. When the valve disc 171 of the partition member 135 undergoes a first displacement due to oil flowing into the variable chamber 191 as the piston 18 moves toward the extension side, the valve disc 171 can discharge oil from the inner chamber 196, which is at least a portion of the passage 201, to the lower chamber 20 in the cylinder 2 via the notch 178 formed in the elastic body 172, the outer chamber 197, and the connecting passage 195. Furthermore, when the valve disc 171 undergoes this first displacement, the valve disc 171 can discharge oil from the outer chamber 197, which is at least a portion of the passage 201, to the lower chamber 20 in the cylinder 2 via the connecting passage 195.

The frequency sensitive mechanism 130 also has a stopper member 188. When the valve disc 171 undergoes a second displacement greater than the first displacement, the stopper member 188 closes the notch 178 in the elastic body 172, thereby forming a closed inner chamber 196 between the passage 201 and the valve disc 171, as shown in FIG. 7. In this state, the stopper member 188 restricts the outward movement of oil within the inner chamber 196. When the valve disc 171 undergoes the second displacement, the partition member 135 closes the inner chamber 196 on one side, resulting in a hydraulic lock state in which further displacement toward the stopper member 188 is suppressed.

With the mounting shaft portion 28 inserted into each, the annular member 117, disc 116, disc 115, multiple discs 114, multiple discs 113, disc 112, disc 111, piston 18, disc 51, damping valve 52, disc 53, disc 54, pilot case 55, disc 56, disc 57, multiple discs 58, disc 59, disc 60, housing main body 131, disc 132, disc 133, and disc 134 shown in Figure 3 are stacked on the shaft step portion 29 in this order on the piston rod 21. At this time, the pilot case 55 fits the seal member 86 of the damping valve 52 into the outer cylindrical portion 73.

As shown in FIG. 4, the partition member 135 is placed on the seat portion 154 of the housing main body 131 with the mounting shaft portion 28 and discs 133 and 134 inserted inside. At this time, the elastic body 172 of the partition member 135 is fitted into the cylindrical portion 153 of the housing main body 131. Furthermore, with the mounting shaft portion 28 inserted inside each, disc 136, disc 137, disc 138, disc 139, disc 140, multiple discs 141, and annular member 144 are placed on disc 134 and the valve disc 171 of the partition member 135, in that order.

With the components from annular member 117 to annular member 144 positioned on the piston rod 21 in this manner, a nut 211 is threaded onto the male threads 31 (shown in Figure 3) of the mounting shaft portion 28 that protrudes beyond the annular member 144. As a result, the inner periphery or entirety of the annular member 117, disc 116, disc 115, multiple discs 114, multiple discs 113, disc 112, disc 111, piston 18, disc 51, damping valve 52, disc 53, disc 54, pilot case 55, disc 56, disc 57, multiple discs 58, disc 59, disc 60, housing main body 131, disc 132, disc 133, disc 134, disc 136, disc 137, disc 138, disc 139, disc 140, multiple discs 141, and annular member 144 are clamped axially between the shaft step portion 29 of the piston rod 21 and the nut 211. At this time, the inner periphery of the partition member 135 is not clamped in the axial direction. In this state, the valve disc 171 of the partition member 135 abuts against the seat portion 154 of the housing main body 131 and the disc 136 of the support member 185. Also, in this state, the protrusion 182 of the abutment portion 176 of the partition member 135 abuts against the disc 141 of the stopper member 188 with an interference fit.

As shown in FIG. 1, the base valve 25 described above is provided between the inner tube 3 and the bottom member 12 of the outer tube 4. This base valve 25 includes a base valve member 221, a disc valve 222, a disc valve 223, and a mounting pin 224. The base valve 25 is mounted on the bottom member 12 at the base valve member 221 and is fitted to the inner tube 3 at the base valve member 221. The base valve member 221 separates the lower chamber 20 from the reservoir chamber 6. The disc valve 222 is provided below the base valve member 221, i.e., on the reservoir chamber 6 side. The disc valve 223 is provided above the base valve member 221, i.e., on the lower chamber 20 side. The mounting pin 224 attaches the disc valves 222 and 223 to the base valve member 221.

The base valve member 221 has an annular shape, and a mounting pin 224 is inserted through its radial center. The base valve member 221 is formed with multiple passage holes 225 and multiple passage holes 226. The multiple passage holes 225 allow oil to flow between the lower chamber 20 and the reservoir chamber 6. The multiple passage holes 226 are arranged radially outward of the multiple passage holes 225 of the base valve member 221. The multiple passage holes 226 allow oil to flow between the lower chamber 20 and the reservoir chamber 6. The disk valve 222 on the reservoir chamber 6 side allows oil to flow from the lower chamber 20 to the reservoir chamber 6 via the passage hole 225. Meanwhile, the disk valve 222 restricts oil from flowing from the reservoir chamber 6 to the lower chamber 20 via the passage hole 225. The disk valve 223 allows oil to flow from the reservoir chamber 6 to the lower chamber 20 via the passage hole 226. On the other hand, the disc valve 223 restricts the flow of oil from the lower chamber 20 to the reservoir chamber 6 through the passage hole 226.

The disc valve 222 and the base valve member 221 form a damping valve mechanism 227. The damping valve mechanism 227 opens during the compression stroke of the shock absorber 1, allowing hydraulic fluid to flow from the lower chamber 20 to the reservoir chamber 6 and generating a damping force. The disc valve 223 and the base valve member 221 form a suction valve mechanism 228. The suction valve mechanism 228 opens during the extension stroke of the shock absorber 1, allowing hydraulic fluid to flow from the reservoir chamber 6 into the lower chamber 20. The suction valve mechanism 228 primarily functions to allow hydraulic fluid to flow from the reservoir chamber 6 to the lower chamber 20 without generating any substantial damping force, thereby compensating for any hydraulic fluid shortage caused by the extension of the piston rod 21 from the cylinder 2.

Next, we will explain the main operation of shock absorber 1.

"When it is assumed that the frequency sensitive mechanism 130 does not act during the extension stroke, and only the extension side damping force mechanism 41 and the damping force mechanism 110 act."
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 from the upper chamber 19 flows into the lower chamber 20 via the passage 43, the throttle 82, the rod chamber 83, the throttle 92, the back pressure chamber 100, and the fixed orifice 105 shown in FIG. 3. This generates a damping force with an orifice characteristic (the damping force is approximately proportional to the square of the piston speed). Therefore, the characteristic of the damping force relative to the piston speed when the piston speed is slower than the first predetermined value is such that the rate of increase of the damping force relative to an increase in the piston speed is relatively high.

When the piston speed is equal to or greater than the first predetermined value and less than the second predetermined value, oil from the upper chamber 19 passes through the passage 43, the throttle 82, the rod chamber 83, the throttle 92, the back pressure chamber 100, and flows between the disc valve 99 and the valve seat 75 into the lower chamber 20 while opening the disc valve 99. This generates a damping force with valve characteristics (damping force is approximately proportional to piston speed). Therefore, when the piston speed is equal to or greater than the first predetermined value and less than the second predetermined value, the damping force characteristic with respect to piston speed is such that the rate of increase in damping force relative to an increase in piston speed is lower than when the piston speed is less than the first predetermined value.

When the piston speed exceeds the second predetermined value, the force (hydraulic pressure) acting on the damping valve 52 becomes greater when the opening force applied from the passage 43 exceeds the closing force applied from the back pressure chamber 100. Therefore, in this region, as the piston speed increases, the damping valve 52 opens by moving away from the valve seat 48 of the piston 18. Therefore, in addition to flowing from the upper chamber 19 through the passage 43, the throttle 82, the rod chamber 83, the throttle 92, the back pressure chamber 100, and between the disc valve 99 and the valve seat 75 to the lower chamber 20, the hydraulic fluid also flows from the passage 43 between the damping valve 52 and the valve seat 48 to the lower chamber 20. Therefore, when the piston speed is greater than the second predetermined value, the rate of increase in damping force relative to an increase in piston speed is lower than when the piston speed is greater than the first predetermined value but less than the second predetermined value.

"Assuming that the frequency sensitive mechanism 130 does not operate during the compression stroke and only the compression side damping force mechanism 42 operates"
In this case, when the piston speed is slower than the third predetermined value, the hydraulic fluid from the lower chamber 20 flows into the upper chamber 19 via the passage 44 shown in FIG. 2 and the fixed orifice 123 of the disc valve 122. This generates a damping force with orifice characteristics. Therefore, when the piston speed is slower than the third predetermined value, the damping force characteristic with respect to the piston speed is such that the rate of increase in the damping force relative to an increase in the piston speed is relatively high.

When the piston speed exceeds the third predetermined value, oil introduced from the lower chamber 20 into the passage 44 opens the disc valve 122 and flows between the disc valve 122 and the valve seat 49 into the upper chamber 19. This generates a damping force with valve characteristics. Therefore, when the piston speed is equal to or greater than the third predetermined value, the damping force characteristic with respect to piston speed is such that the rate of increase in damping force relative to an increase in piston speed is lower than when the piston speed is below the third predetermined value.

"When the frequency sensitive mechanism 130 acts during the extension stroke"
In this embodiment, the frequency sensitive mechanism 130 varies the damping force depending on the piston frequency even when the piston speed is the same.

During the extension stroke, oil is introduced from the upper chamber 19 into the variable chamber 191 of the frequency sensitive mechanism 130 via the passage 43, the throttle 82, the rod chamber 83, and the throttle 162 shown in Figure 4. As a result, the valve disc 171 of the partition member 135, which is in contact with the seat portion 154 and the disc 136 of the support member 185, is deformed by pressure load in a tapered shape with its outer periphery tapering away from the seat portion 154, with the contact point with the disc 136 acting as a fulcrum. At this time, the partition member 135 compresses and deforms mainly the protruding portion 182 of the contact portion 176 that abuts the stopper member 188.

Here, when the piston frequency is high, the stroke of the piston 18 is small during the extension stroke. Therefore, the amount of oil introduced from the upper chamber 19 into the variable chamber 191 via the passage 43, the throttle 82, the rod chamber 83, and the throttle 162 is small. Therefore, although the valve disc 171 of the partition member 135 deforms as described above due to the pressure load, it does not deform to near its limit.

Therefore, during the extension stroke when the piston frequency is high, the valve disc 171 of the partition member 135 of the frequency sensitive mechanism 130 deforms as described above, introducing hydraulic fluid from the upper chamber 19 into the variable chamber 191. This reduces the flow rate of hydraulic fluid from the upper chamber 19 through the passage 43, the throttle 82, the rod chamber 83, the throttle 92, and the back pressure chamber 100 to the lower chamber 20, opening the damping force mechanism 110. In addition, the flow rate of hydraulic fluid from the passage 43 to the lower chamber 20, opening the damping force mechanism 41, also reduces. Furthermore, introducing hydraulic fluid from the upper chamber 19 into the variable chamber 191 suppresses pressure increases in the back pressure chamber 100 compared to when the variable chamber 191 is not present, making it easier for the damping valve 52 of the damping force mechanism 41 to open. These factors result in a softer damping force on the extension side. Here, the inner circumferential side of the partitioning member 135 is spaced apart from the disk 132 and is supported on only one side by the disk 136. For this reason, the partitioning member 135 is prone to deformation such that the inner circumferential side approaches the disk 132. As a result, the partitioning member 135 is easily compressed and deformed, mainly at the protruding portion 182 of the abutting portion 176 on the outer circumferential side.

During the extension stroke, as described above, the valve disc 171 of the partition member 135 deforms in a tapered shape toward the stopper member 188, with the point of contact with the disc 136 of the support member 185 as the fulcrum. In the initial stage of this deformation, the valve disc 171 itself deforms, and compresses and deforms mainly the protruding portion 182 of the abutment portion 176 that abuts against the disc 141 of the stopper member 188.

As the deformation of the valve disc 171 toward the stopper member 188 progresses, the valve disc 171 itself deforms further, and further compresses and deforms, primarily the protruding portion 182 of the abutment portion 176. At the same time, the valve disc 171 abuts against the outer periphery of the disc 137 of the support member 185, deforming the outer periphery of the disc 137 in a tapered shape toward the stopper member 188.

As the deformation of the valve disc 171 toward the stopper member 188 progresses, the valve disc 171 itself deforms further, and further compresses and deforms, primarily the protruding portion 182 of the abutment portion 176. At the same time, the valve disc 171 deforms the outer periphery of the disc 137 and the outer periphery of the disc 138 of the support member 185 in a tapered shape toward the stopper member 188.

However, during the extension stroke when the piston frequency is high, the pressure difference between the variable chamber 191 and variable chamber 192 of the valve disc 171 is small in the partition member 135. Therefore, the displacement of the valve disc 171 toward the stopper member 188 becomes a first displacement, where the displacement amount is below a predetermined value, and the notch 178 of the abutment portion 176 is not blocked by the stopper member 188. Therefore, the partition member 135 discharges oil from the inner chamber 196 of the variable chamber 192 of the frequency sensitive mechanism 130 to the outer chamber 197 through the passage in the notch 178, and discharges oil from the outer chamber 197 to the lower chamber 20 through the communication passage 195.

On the other hand, during the extension stroke when the piston frequency is low, the stroke of the piston 18 is large. Therefore, a large amount of oil is introduced from the upper chamber 19 to the variable chamber 191 via the passage 43, the throttle 82, the rod chamber 83, and the throttle 162. Therefore, although oil flows from the upper chamber 19 to the variable chamber 191 early in the stroke of the piston 18, the valve disc 171 of the partition member 135 subsequently deforms to near its limit and no longer deforms. As a result, oil no longer flows from the upper chamber 19 to the variable chamber 191. This prevents a decrease in the flow rate of oil from the upper chamber 19 through the passage 43, the throttle 82, the rod chamber 83, the throttle 92, and the back pressure chamber 100 to the lower chamber 20, while opening the damping force mechanism 110. Furthermore, the flow rate of oil from the passage 43 to the lower chamber 20, while opening the damping force mechanism 41, also does not decrease. In addition, because oil is not being introduced into the variable chamber 191 from the upper chamber 19, the pressure in the back pressure chamber 100 increases, making it difficult for the damping valve 52 of the damping force mechanism 41 to open. As a result, the damping force on the extension side becomes stronger than at high frequencies. Even during the extension stroke when the piston frequency is low, the valve disc 171 deforms, deforming the support member 185, just as it does when the piston frequency is high.

However, at the beginning of the extension stroke when the piston frequency is low and the displacement of the valve disc 171 toward the stopper member 188 is the first displacement, where the displacement amount is less than a predetermined value, the notch 178 of the abutment portion 176 is not blocked by the stopper member 188. In this state, the partition member 135 discharges oil from the inner chamber 196 of the variable chamber 192 to the outer chamber 197 through the passage in the notch 178, and discharges oil from the outer chamber 197 to the lower chamber 20 through the communication passage 195.

On the other hand, after the initial stage of the extension stroke when the piston frequency is low, the pressure difference between variable chamber 191 and variable chamber 192 increases, increasing the pressure load on the valve disc 171. This causes the valve disc 171 to displace toward the stopper member 188, a second displacement exceeding a predetermined value. As a result, the notch 178 in the abutment portion 176 is closed by the stopper member 188, as shown in FIG. 7 . In this state, the partition member 135 prevents oil from the inner chamber 196 of the variable chamber 192 from discharging to the outer chamber 197 through the passage in the notch 178. With the inner chamber 196 closed in this manner, the pressure in the inner chamber 196 increases as the pressure in the variable chamber 191 increases. This prevents the pressure difference between the variable chamber 191 and the variable chamber 192 from widening. This particularly prevents the inner side of the valve disc 171 from deforming too much and increasing stress on the inner side.

During the compression stroke, the pressure in the lower chamber 20 increases, but the valve disc 171 of the partition member 135 of the frequency sensitive mechanism 130 abuts against the seat portion 154 of the housing main body 131, suppressing the expansion of the variable chamber 192. This suppresses the amount of oil introduced from the lower chamber 20 into the variable chamber 192 via the communication passage 195. As a result, the flow rate of oil introduced from the lower chamber 20 into the passage 44, passing through the damping force mechanism 42 and flowing into the upper chamber 19 remains almost constant. This results in a hard damping force. During the compression stroke, if the piston speed increases and the pressure in the variable chamber 192 exceeds the pressure in the variable chamber 191 by more than a predetermined value, the inner periphery of the valve disc 171 of the partition member 135 moves away from the disc 136. In other words, the check valve 205 opens. As a result, oil flows from the lower chamber 20 to the upper chamber 19 via the communication passage 195, variable chamber 192, variable chamber 191, throttle 162, rod chamber 83, throttle 82, and passage 43. In this way, by opening the check valve 205, the pressure difference between the variable chamber 192 side and the variable chamber 191 side of the valve disc 171 of the partition member 135 is suppressed. This prevents the valve disc 171 from bending excessively.

The aforementioned Patent Document 1 discloses a shock absorber equipped with a partition disk that partitions a passageway. The partition disk of this shock absorber has a flexible, circular, flat, perforated disk made of a metal material with a uniform thickness, and an elastic member made of a rubber material fixed to the outer periphery of the disk. The partition disk has stopper portions of the elastic member formed intermittently around the circumferential direction of the disk, which serves as a valve member. In other words, the grooves between adjacent stopper portions around the circumferential direction of the partition disk have the disk, which serves as the valve member, at their bottom. With this structure, the pressure difference between both sides of the valve member increases, which may reduce the durability of the valve member.

In the shock absorber 1 of the first embodiment, the frequency sensitive mechanism 130, which is provided in the passage 201 and generates a damping force, has a valve disc 171, which is a valve member. When the valve disc 171 undergoes a first displacement due to oil flowing in as the piston 18 moves toward the extension side, the oil in the inner chamber 196 in the passage 201 can be discharged to the lower chamber 20 in the cylinder 2 via the notch 178 formed in the elastic body 172, the outer chamber 197, and the communication passage 195. The frequency sensitive mechanism 130 also has a stopper member 188. When the valve disc 171 undergoes a second displacement greater than the first displacement, the stopper member 188 closes the notch 178 in the elastic body 172, thereby forming a closed inner chamber 196 between the passage 201 and the valve disc 171. In this state, the stopper member 188 restricts the movement of oil in the inner chamber 196. In this way, by restricting the movement of oil within the inner chamber 196 when the valve disc 171 undergoes a second displacement greater than the first displacement, when the pressure in the variable chamber 191 on the opposite side of the valve disc 171 from the inner chamber 196 increases, the pressure within the inner chamber 196 can be increased accordingly. This prevents the pressure difference between the two sides of the valve disc 171 from becoming too large. As a result, the shock absorber 1 can improve the durability of the valve disc 171, which is the valve member.

In addition, since the elastic body 172 of the shock absorber 1 is integrally formed with the valve disc 171, which is the valve member, an increase in the number of parts can be suppressed.

Second Embodiment
Next, the second embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 8. Note that parts common to the first embodiment will be designated by the same names and symbols.

In the second embodiment, as shown in FIG. 8, partition member 135A, which is partially different from partition member 135, is used in place of partition member 135. Partition member 135A has elastic body 172A, which is partially different from elastic body 172, instead of elastic body 172. Elastic body 172A has abutting portion 176A, which is partially different from abutting portion 176, instead of abutting portion 176. Abutting portion 176A has a notch 178A, which is partially different from notch 178, instead of notch 178. Elastic body 172A has protrusion 182A, which is partially different from protrusion 182, instead of protrusion 182.

The notch 178A is a groove recessed from the tip of the abutting portion 176A opposite the seal portion 175 toward the seal portion 175 in the axial direction of the partitioning member 135A. The notch 178A penetrates the abutting portion 176A in the radial direction of the abutting portion 176A. The abutting portion 176A has multiple notches 178A of the same shape provided at equal intervals around the circumferential direction of the partitioning member 135A. The bottom of the notch 178A on the seal portion 175 side in the axial direction of the partitioning member 135A is curved in an arc shape when viewed radially of the partitioning member 135A.

Protrusion 182A protrudes from main body portion 181 on the opposite side of seal portion 175 in the axial direction of partition member 135A. Protrusion 182A is formed between adjacent notches 178A in the circumferential direction of partition member 135A. The abutment portion 176A has the same number of protrusions 182A of the same shape as notches 178A, equally spaced apart in the circumferential direction of partition member 135A. Protrusion 182A is convex, protruding from main body portion 181 on the opposite side of seal portion 175 in the axial direction of partition member 135A. The tip of protrusion 182A, on the opposite side of seal portion 175 in the axial direction of partition member 135A, is curved in an arc shape when viewed radially of partition member 135A. The length of the protrusion 182A in the circumferential direction of the partition member 135A is equal to the length of the cutout 178A in the circumferential direction of the partition member 135A. The abutment portion 176A has multiple cutouts 178A that are smoothly continuous in the circumferential direction.

When a pressure load is generated in the partition member 135A due to the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) and the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4), primarily the protruding portion 182A of the abutment portion 176A of the elastic body 172A that abuts against the stopper member 188 (see FIG. 4) is elastically deformed. In the first displacement, in which the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) is small and the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) is less than a predetermined value, primarily the protruding portion 182A of the abutment portion 176A is elastically deformed, but the notch 178A is not blocked by the stopper member 188 (see FIG. 4).

On the other hand, in the partition member 135A, the pressure difference between the variable chamber 191 (see Figure 4) and the variable chamber 192 (see Figure 4) increases, the pressure load increases, and the valve disc 171 (see Figure 4) is displaced toward the stopper member 188 (see Figure 4). In the second displacement, where the displacement amount exceeds a predetermined value, the abutment portion 176A, mainly the protrusion portion 182A, undergoes large elastic deformation, and the cutout portion 178A is blocked by the stopper member 188 (see Figure 4).

In other words, the stopper member 188 (see FIG. 4) does not block the notch 178A of the abutment portion 176A during a first displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by a predetermined amount or less. On the other hand, the stopper member 188 (see FIG. 4) does block the notch 178A of the abutment portion 176A during a second displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount greater than the predetermined amount.

During the extension stroke when the piston frequency is high, or at the beginning of the extension stroke when the piston frequency is low, when the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by a first displacement amount equal to or less than a predetermined value, the partition member 135A does not block the notch 178A of the abutment portion 176A with the stopper member 188 (see FIG. 4). In this state, the partition member 135A discharges oil from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) to the outer chamber 197 (see FIG. 4) through the passage in the notch 178A, and discharges oil from the outer chamber 197 (see FIG. 4) to the lower chamber 20 (see FIG. 4) through the communication passage 195 (see FIG. 4). This causes the valve disc 171 (see FIG. 4) to deform instantly, instantly expanding the variable chamber 191.

On the other hand, after the initial stage of the extension stroke when the piston frequency is low, the partition member 135A experiences a second displacement where the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) exceeds a predetermined value. This causes a large elastic deformation, primarily of the protruding portion 182A of the abutment portion 176A, and the cutout portion 178A is blocked by the stopper member 188. In this state, the partition member 135A prevents oil from being discharged from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) into the outer chamber 197 (see FIG. 4). With the inner chamber 196 (see FIG. 4) closed in this manner, the pressure in the inner chamber 196 (see FIG. 4) increases as the pressure in the variable chamber 191 (see FIG. 4) increases, thereby preventing the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) from increasing. Therefore, even in the second embodiment, the durability of the valve disc 171 (see FIG. 4) can be improved.

[Third embodiment]
Next, the third embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 9. Note that parts common to the first embodiment will be designated by the same names and symbols.

In the third embodiment, as shown in FIG. 9, partition member 135B, which is partially different from partition member 135, is used in place of partition member 135. Partition member 135B has elastic body 172B, which is partially different from elastic body 172, instead of elastic body 172. Elastic body 172B has abutting portion 176B, which is partially different from abutting portion 176, instead of abutting portion 176. Abutting portion 176B has a notch 178B, which is partially different from notch 178, instead of notch 178. Elastic body 172B has a protrusion 182B, which is partially different from protrusion 182, instead of protrusion 182.

The notch 178B is a groove recessed from the tip of the abutting portion 176B opposite the seal portion 175 toward the seal portion 175 in the axial direction of the partitioning member 135B. The notch 178B penetrates the abutting portion 176B in the radial direction of the abutting portion 176B. The abutting portion 176B has multiple notches 178B of the same shape provided at equal intervals around the circumference of the partitioning member 135B.

The cutout 178B has a bottom surface 179B and a pair of wall surface portions 180B. The bottom surface 179B is flat and extends perpendicular to the axial direction of the partition member 135B. The bottom surface 179B of the cutout 178B is formed on the main body 181. The pair of wall surface portions 180B are inclined at the same angle relative to the bottom surface 179B. The further away the pair of wall surface portions 180B are from the bottom surface 179B in the axial direction of the partition member 135B, the wider the distance between them in the circumferential direction of the partition member 135B.

The protruding portion 182B protrudes from the main body portion 181 on the opposite side to the seal portion 175 in the axial direction of the partition member 135B.
The protrusions 182B are formed between adjacent notches 178B in the circumferential direction of the partition member 135B. The abutting portion 176B is provided with the same number of protrusions 182B as the notches 178B, and are equally spaced apart in the circumferential direction of the partition member 135B.

The length of the notch 178B in the circumferential direction of the partition member 135B is longer than the length of the protrusion 182B in the circumferential direction of the partition member 135B. The notch 178B is arc-shaped when viewed in the axial direction of the partition member 135B. The wall surface 180B of the notch 178B is formed on the protrusion 182B. The wall surface 180B and wall surface 180B that are adjacent and continuous in the circumferential direction of the partition member 135B are formed on the protrusion 182B.

When a pressure load is generated in the partition member 135B due to the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) and the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4), primarily the protruding portion 182B of the abutment portion 176B that abuts against the stopper member 188 (see FIG. 4) of the elastic body 172B elastically deforms. In the first displacement, in which the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) is small and the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) is less than a predetermined value, primarily the protruding portion 182B of the abutment portion 176B elastically deforms, but the notch 178B is not blocked by the stopper member 188 (see FIG. 4).

On the other hand, in the partition member 135B, the pressure difference between the variable chamber 191 (see Figure 4) and the variable chamber 192 (see Figure 4) increases, the pressure load increases, and the valve disc 171 (see Figure 4) is displaced toward the stopper member 188 (see Figure 4) (second displacement) exceeds a predetermined value. In this case, the abutment portion 176B, mainly the protrusion 182B, undergoes large elastic deformation, and the cutout portion 178B is blocked by the stopper member 188 (see Figure 4).

In other words, the stopper member 188 (see FIG. 4) does not block the notch 178B of the abutment portion 176B during a first displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount equal to or less than a predetermined value. On the other hand, the stopper member 188 (see FIG. 4) does block the notch 178B of the abutment portion 176B during a second displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount greater than a predetermined value.

During the extension stroke when the piston frequency is high, or at the beginning of the extension stroke when the piston frequency is low, when the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by a first displacement amount equal to or less than a predetermined value, the partition member 135B does not block the notch 178B of the abutment portion 176B with the stopper member 188 (see FIG. 4). In this state, the partition member 135B discharges oil from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) to the outer chamber 197 (see FIG. 4) through the passage in the notch 178B, and discharges oil from the outer chamber 197 (see FIG. 4) to the lower chamber 20 (see FIG. 4) through the communication passage 195 (see FIG. 4). This causes the valve disc 171 (see FIG. 4) to deform instantly, instantly expanding the variable chamber 191.

On the other hand, after the above-mentioned initial stage of the extension stroke when the piston frequency is low, the partition member 135B experiences a second displacement in which the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) exceeds a predetermined value. This causes a large elastic deformation, mainly of the protruding portion 182B of the abutment portion 176B, and the cutout portion 178B is blocked by the stopper member 188. In this state, the partition member 135B prevents oil from being discharged from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) into the outer chamber 197 (see FIG. 4). With the inner chamber 196 (see FIG. 4) closed in this manner, the pressure in the inner chamber 196 (see FIG. 4) increases as the pressure in the variable chamber 191 (see FIG. 4) increases, thereby preventing the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) from increasing. Therefore, even in the third embodiment, the durability of the valve disc 171 (see FIG. 4) can be improved.

[Fourth embodiment]
Next, the fourth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 10. Note that parts common to the first embodiment will be designated by the same names and symbols.

In the fourth embodiment, as shown in FIG. 10, partition member 135C, which is partially different from partition member 135, is used in place of partition member 135. Partition member 135C has elastic body 172C, which is partially different from elastic body 172, instead of elastic body 172. Elastic body 172C has abutting portion 176C, which is partially different from abutting portion 176, instead of abutting portion 176. Abutting portion 176C has a notch 178C, which is partially different from notch 178, instead of notch 178. Elastic body 172C has protrusion 182C, which is partially different from protrusion 182, instead of protrusion 182.

The notch 178C is a groove recessed from the tip of the abutting portion 176C opposite the seal portion 175 toward the seal portion 175 in the axial direction of the partition member 135C. The notch 178C penetrates the abutting portion 176C in the radial direction of the abutting portion 176C. The abutting portion 176C has multiple notches 178C of the same shape provided at equal intervals around the circumferential direction of the partition member 135C. When viewed in the radial direction of the partition member 135C, the entire notch 178C is curved in an arc shape.

The protruding portion 182C protrudes from the main body portion 181 on the opposite side to the seal portion 175 in the axial direction of the partition member 135C.
The protrusions 182C are formed between adjacent notches 178C in the circumferential direction of the partition member 135C. The abutting portion 176C is provided with the same number of protrusions 182C of the same shape as the notches 178C, spaced equally apart in the circumferential direction of the partition member 135C. The length of the protrusions 182C in the circumferential direction of the partition member 135C is longer than the length of the notches 178C in the circumferential direction of the partition member 135C.

When a pressure load is generated in the partition member 135C due to the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) and the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4), the protrusion 182C, primarily of the abutment portion 176C of the elastic body 172C that abuts against the stopper member 188 (see FIG. 4), elastically deforms. In the first displacement, in which the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) is small and the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) is less than a predetermined value, the protrusion 182C, primarily of the abutment portion 176C, elastically deforms, but the notch 178C is not blocked by the stopper member 188 (see FIG. 4).

On the other hand, in the partition member 135C, the pressure difference between the variable chamber 191 (see Figure 4) and the variable chamber 192 (see Figure 4) increases, the pressure load increases, and the valve disc 171 (see Figure 4) is displaced toward the stopper member 188 (see Figure 4) (second displacement) exceeds a predetermined value. In this case, the abutment portion 176C, mainly the protrusion 182C, undergoes large elastic deformation, and the cutout portion 178C is blocked by the stopper member 188 (see Figure 4).

In other words, the stopper member 188 (see FIG. 4) does not close the notch 178C of the abutment portion 176C during a first displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount equal to or less than a predetermined value. On the other hand, the stopper member 188 (see FIG. 4) does close the notch 178C of the abutment portion 176C during a second displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount greater than a predetermined value.

During the extension stroke when the piston frequency is high, or at the beginning of the extension stroke when the piston frequency is low, when the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by a first displacement amount equal to or less than a predetermined value, the partition member 135C does not block the notch 178C of the abutment portion 176C with the stopper member 188 (see FIG. 4). In this state, the partition member 135C discharges oil from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) to the outer chamber 197 (see FIG. 4) through the passage in the notch 178C, and discharges oil from the outer chamber 197 (see FIG. 4) to the lower chamber 20 (see FIG. 4) through the communication passage 195 (see FIG. 4). This causes the valve disc 171 (see FIG. 4) to deform instantly, instantly expanding the variable chamber 191.

On the other hand, after the above-mentioned initial stage of the extension stroke when the piston frequency is low, the partition member 135C experiences a second displacement in which the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) exceeds a predetermined value. This causes a large elastic deformation, mainly of the protruding portion 182C of the abutment portion 176C, and the cutout portion 178C is blocked by the stopper member 188. In this state, the partition member 135C prevents oil from being discharged from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) into the outer chamber 197 (see FIG. 4). With the inner chamber 196 (see FIG. 4) closed in this manner, the pressure in the inner chamber 196 (see FIG. 4) increases as the pressure in the variable chamber 191 (see FIG. 4) increases, thereby preventing the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) from increasing. Therefore, even in the fourth embodiment, the durability of the valve disc 171 (see FIG. 4) can be improved.

Fifth Embodiment
Next, the fifth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 11. Note that parts common to the first embodiment will be designated by the same names and symbols.

In the fifth embodiment, as shown in FIG. 11, partition member 135D, which is partially different from partition member 135, is used in place of partition member 135. Partition member 135D has elastic body 172D, which is partially different from elastic body 172, instead of elastic body 172. Elastic body 172D has abutting portion 176D, which is partially different from abutting portion 176, instead of abutting portion 176. Abutting portion 176D has a notch 178D, which is partially different from notch 178, instead of notch 178. Elastic body 172D has protrusion 182D, which is partially different from protrusion 182, instead of protrusion 182.

The protrusion 182D protrudes from the main body portion 181 on the opposite side of the seal portion 175 in the axial direction of the partition member 135D. The abutment portion 176D has multiple protrusions 182D of the same shape, spaced equally apart around the circumference of the partition member 135D. When viewed in the radial direction of the partition member 135D, the entire protrusion 182D is curved in an arc shape.

The notch 178D is a groove recessed from the tip of the abutting portion 176D opposite the seal portion 175 toward the seal portion 175 in the axial direction of the partition member 135D. The notch 178D penetrates the abutting portion 176D in the radial direction of the abutting portion 176D. The abutting portion 176D has the same shaped notches 178D in the same number as the protrusions 182D, spaced equally apart circumferentially around the partition member 135D.

The notch 178D has a bottom surface 179D and a pair of wall surface portions 180D. The bottom surface 179D is flat and extends perpendicular to the axial direction of the partition member 135D. The bottom surface 179D of the notch 178D is formed in the main body portion 181. Adjacent wall surface portions 180D in the circumferential direction of the partition member 135D are continuously formed into a single protrusion 182D. The length of the notch 178D in the circumferential direction of the partition member 135D is longer than the length of the protrusion 182D.

When a pressure load is generated in the partition member 135D due to the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) and the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4), primarily the protruding portion 182D of the abutment portion 176D that abuts against the stopper member 188 (see FIG. 4) of the elastic body 172D elastically deforms. In the first displacement, in which the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) is small and the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) is less than a predetermined value, primarily the protruding portion 182D of the abutment portion 176D elastically deforms, but the notch 178D is not blocked by the stopper member 188 (see FIG. 4).

On the other hand, in the partition member 135D, the pressure difference between the variable chamber 191 (see Figure 4) and the variable chamber 192 (see Figure 4) increases, the pressure load increases, and the valve disc 171 (see Figure 4) is displaced toward the stopper member 188 (see Figure 4) (second displacement) exceeds a predetermined value. In this case, the abutment portion 176D, mainly the protrusion 182D, undergoes large elastic deformation, and the cutout portion 178D is blocked by the stopper member 188 (see Figure 4).

In other words, the stopper member 188 (see FIG. 4) does not close the notch 178D of the abutment portion 176D during a first displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount equal to or less than a predetermined value. On the other hand, the stopper member 188 (see FIG. 4) does close the notch 178D of the abutment portion 176D during a second displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount greater than a predetermined value.

During the extension stroke when the piston frequency is high, or at the beginning of the extension stroke when the piston frequency is low, when the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by a first displacement amount equal to or less than a predetermined value, the partition member 135D does not block the notch 178D of the abutment portion 176D with the stopper member 188 (see FIG. 4). In this state, the partition member 135D discharges oil from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) to the outer chamber 197 (see FIG. 4) through the passage in the notch 178D, and discharges oil from the outer chamber 197 (see FIG. 4) to the lower chamber 20 (see FIG. 4) through the communication passage 195 (see FIG. 4). This causes the valve disc 171 (see FIG. 4) to deform instantly, instantly expanding the variable chamber 191.

On the other hand, after the initial stage of the extension stroke when the piston frequency is low, the partition member 135D experiences a second displacement in which the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) exceeds a predetermined value. This causes a large elastic deformation of the abutment portion 176D, primarily the protrusion 182D, and the cutout portion 178D is blocked by the stopper member 188. In this state, the partition member 135D prevents oil from being discharged from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) into the outer chamber 197 (see FIG. 4). With the inner chamber 196 (see FIG. 4) closed in this manner, the pressure in the inner chamber 196 (see FIG. 4) increases as the pressure in the variable chamber 191 (see FIG. 4) increases, thereby preventing the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) from increasing. Therefore, even in the fifth embodiment, the durability of the valve disc 171 (see FIG. 4) can be improved.

Sixth Embodiment
Next, the sixth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 12. Note that parts common to the first embodiment will be designated by the same names and symbols.

In the sixth embodiment, as shown in FIG. 12, partition member 135E, which is partially different from partition member 135, is used in place of partition member 135. Partition member 135E has elastic body 172E, which is partially different from elastic body 172, instead of elastic body 172. Elastic body 172E has abutment portion 176E, which is partially different from abutment portion 176, instead of abutment portion 176. Abutment portion 176E has a notch 178E, which is partially different from notch 178, instead of notch 178. Elastic body 172E has protrusion 182E, which is partially different from protrusion 182, instead of protrusion 182.

The notch 178E is a groove recessed from the tip of the abutting portion 176E opposite the seal portion 175 toward the seal portion 175 in the axial direction of the partition member 135E. The notch 178E penetrates the abutting portion 176E in the radial direction of the abutting portion 176E. The abutting portion 176E has multiple notches 178E of the same shape provided at equal intervals around the circumferential direction of the partition member 135E.

The cutout portion 178E has a bottom surface portion 179E and a pair of wall surface portions 180E. The bottom surface portion 179E is flat and extends perpendicular to the axial direction of the partition member 135E. The bottom surface portion 179E of the cutout portion 178E is formed on the main body portion 181. The pair of wall surface portions 180E are inclined at the same angle relative to the bottom surface portion 179E. The distance between the pair of wall surface portions 180E in the circumferential direction of the partition member 135E increases as they move away from the bottom surface portion 179E in the axial direction of the partition member 135E.

The protruding portion 182E protrudes from the main body portion 181 on the opposite side to the seal portion 175 in the axial direction of the partition member 135E.
The protrusions 182E are formed between adjacent notches 178E in the circumferential direction of the partition member 135E. The abutting portion 176E is provided with the same number of protrusions 182E of the same shape as the notches 178E, spaced equally apart in the circumferential direction of the partition member 135E. The protrusions 182E are provided with wall surfaces 180E on both sides in the circumferential direction of the partition member 135E, spaced apart in the circumferential direction of the partition member 135E.

The length of the notch 178E in the circumferential direction of the partition member 135E is longer than the length of the protrusion 182E in the circumferential direction of the partition member 135E. The notch 178E is arc-shaped when viewed in the axial direction of the partition member 135E.

When a pressure load is generated in the partition member 135E due to the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) and the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4), the abutment portion 176E of the elastic body 172E, which abuts against the stopper member 188 (see FIG. 4), primarily the protrusion 182E, elastically deforms. In the partition member 135E, when the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) is small and the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) is a first displacement below a predetermined value, the abutment portion 176E, primarily the protrusion 182E, elastically deforms, but the notch 178E is not blocked by the stopper member 188 (see FIG. 4).

On the other hand, in the partition member 135E, the pressure difference between the variable chamber 191 (see Figure 4) and the variable chamber 192 (see Figure 4) increases, the pressure load increases, and the valve disc 171 (see Figure 4) is displaced toward the stopper member 188 (see Figure 4) (second displacement) exceeds a predetermined value. This causes large elastic deformation of the abutment portion 176E, mainly the protrusion 182E, and the cutout portion 178E is blocked by the stopper member 188 (see Figure 4).

In other words, the stopper member 188 (see FIG. 4) does not block the notch 178E of the abutment portion 176E during a first displacement in which the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by an amount equal to or less than a predetermined value. On the other hand, the stopper member 188 (see FIG. 4) does block the notch 178E of the abutment portion 176E during a second displacement in which the valve disc 171 is displaced toward the stopper member 188 (see FIG. 4) by an amount greater than a predetermined value.

During the extension stroke when the piston frequency is high, or at the beginning of the extension stroke when the piston frequency is low, when the valve disc 171 (see FIG. 4) is displaced toward the stopper member 188 (see FIG. 4) by a first displacement amount equal to or less than a predetermined value, the partition member 135E does not block the notch 178E of the abutment portion 176E with the stopper member 188 (see FIG. 4). In this state, the partition member 135E discharges oil from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) to the outer chamber 197 (see FIG. 4) through the passage in the notch 178E, and discharges oil from the outer chamber 197 (see FIG. 4) to the lower chamber 20 (see FIG. 4) through the communication passage 195 (see FIG. 4). This causes the valve disc 171 (see FIG. 4) to deform instantly, instantly expanding the variable chamber 191.

On the other hand, after the initial stage of the extension stroke when the piston frequency is low, the partition member 135E experiences a second displacement in which the displacement of the valve disc 171 (see FIG. 4) toward the stopper member 188 (see FIG. 4) exceeds a predetermined value. This causes a large elastic deformation of the abutment portion 176E, primarily the protruding portion 182E, and the cutout portion 178E is blocked by the stopper member 188. In this state, the partition member 135E prevents oil from being discharged from the inner chamber 196 (see FIG. 4) of the variable chamber 192 (see FIG. 4) into the outer chamber 197 (see FIG. 4). With the inner chamber 196 (see FIG. 4) closed in this manner, the pressure in the inner chamber 196 (see FIG. 4) increases as the pressure in the variable chamber 191 (see FIG. 4) increases, thereby preventing the pressure difference between the variable chamber 191 (see FIG. 4) and the variable chamber 192 (see FIG. 4) from increasing. Therefore, even in the sixth embodiment, the durability of the valve disc 171 (see FIG. 4) can be improved.

In the first to sixth embodiments, the abutment portions 176, 176A-176E of the elastic bodies 172, 172A-172E are provided integrally with the valve disc 171. However, this is not limiting. For example, the abutment portions 176, 176A-176E may not be provided on the valve disc 171, but may be provided integrally with the disc 141 closest to the valve disc 171 and facing the valve disc 171 among the multiple discs 141 that make up the stopper member 188. In this case, the abutment portions 176, 176A-176E, which are elastic bodies, are provided on the valve disc 171 side of this disc 141, with the main body portion 181 on the disc 141 side and the cutout portions 178, 178A-178E and protrusions 182, 182A-182E on the side that abuts the valve disc 171.

In the above embodiment, a hydraulic shock absorber was used as an example, but water or air can also be used as the working fluid.

1... shock absorber, 2... cylinder, 18... piston, 19... upper chamber (chamber), 20... lower chamber (chamber), 21... piston rod, 41... damping force mechanism (first damping force mechanism), 43... passage (first passage), 130... frequency sensitive mechanism (second damping force mechanism), 171... valve disc (valve member), 172, 172A-172E... elastic body, 178, 178A-178E... notch, 188... stopper member (restriction portion), 196... inner chamber (pressure chamber), 201... passage (second passage).

Claims (3)

a cylinder in which a working fluid is sealed;
a piston slidably fitted in the cylinder and dividing the interior of the cylinder into two chambers;
a piston rod connected to the piston and extending to the outside of the cylinder;
a first passage that communicates the two chambers by movement of the piston so that the working fluid can flow between them;
a second passage provided 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 valve member that is provided in the second passage, partitioning the second passage, and that is capable of discharging at least a portion of the working fluid in the second passage into the cylinder through a notch formed in an elastic body when the working fluid flows in due to movement of the piston, and a limiting portion that forms a closed pressure chamber between the second passage and the valve member by closing the notch when the valve member undergoes a second displacement, thereby limiting the movement of the working fluid in the pressure chamber; and a second damping force mechanism that generates a damping force, the second damping force mechanism having: a valve member that is provided in the second passage, partitioning the second passage, and that is capable of discharging at least a portion of the working fluid in the second passage into the cylinder through a notch formed in an elastic body when the working fluid flows in due to movement of the piston, and a limiting portion that forms a closed pressure chamber between the second passage and the valve member by closing the notch when the valve member undergoes a second displacement, thereby limiting the movement of the working fluid in the pressure chamber;
A buffer comprising: The shock absorber according to claim 1, wherein the elastic body is integrally formed with the valve member. The shock absorber according to claim 1, wherein the elastic body is provided on a member facing the valve member.