buffer

Abstract

To provide a shock absorber that enables the damping force generation mechanism to operate smoothly. [Solution] This buffer comprises a cylinder in which a working fluid is sealed; a piston slidably fitted inside the cylinder and dividing the inside of the cylinder into a first cylinder chamber and a second cylinder chamber; a first passage through which the working fluid flows out from one of the chambers inside the cylinder as the piston moves; a second passage provided in parallel with the first passage; a valve mechanism provided in the first passage that operates when the first cylinder chamber is under upstream pressure and can adjust the damping force according to the pressure in the main back pressure chamber; a frequency-sensitive mechanism provided in the second passage that changes its volume as a movable member moves; a check valve provided in the second passage that operates when the second cylinder chamber is under upstream pressure; and a first throttling mechanism provided downstream or upstream of the check valve that controls the flow of working fluid to the main back pressure chamber.

Description

Technical Field

[0001] The present invention relates to a shock absorber. This application claims priority based on Japanese Patent Application No. 2022-189298 filed in Japan on November 28, 2022, and incorporates its content herein.

Background Art

[0002] Some shock absorbers have a damping force generation mechanism in which the damping force varies in response to frequency (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a shock absorber, it is required to smoothly operate the damping force generation mechanism.

[0005] Therefore, the present invention provides a shock absorber capable of smoothly operating the damping force generation mechanism.

Means for Solving the Problems

[0006] A shock absorber according to a first aspect of the present invention includes a cylinder in which a working fluid is sealed; a piston slidably fitted inside the cylinder and dividing the inside of the cylinder into a first cylinder chamber and a second cylinder chamber; a first passage through which the working fluid flows out from one of the chambers inside the cylinder as the piston moves; a second passage provided in parallel with the first passage; a valve mechanism provided in the first passage that acts when the first cylinder chamber is under upstream pressure and can adjust the damping force according to the pressure in the main back pressure chamber; a frequency-sensitive mechanism provided in the second passage that changes its volume as a movable member moves; a check valve provided in the second passage that acts when the second cylinder chamber is under upstream pressure; and a first throttling mechanism provided downstream or upstream of the check valve that controls the flow of the working fluid to the main back pressure chamber.

[0007] A damping force generating mechanism according to a second aspect of the present invention comprises a biasing force generating member that is bottomed cylindrical and has a back pressure chamber that generates a biasing force in the valve closing direction in a damping force generating member disposed on the opening side; a valve provided at the bottom of the biasing force generating member and defining a variable chamber on the opposite side from the back pressure chamber, thereby blocking the flow of working fluid from the back pressure chamber to the variable chamber; and a regulating member that abuts against the outer circumference of the valve and restricts the opening of the valve, wherein the valve has a first throttling portion that restricts the inflow of working fluid from the variable chamber to the back pressure chamber. [Effects of the Invention]

[0008] According to the above-described embodiment, it becomes possible to operate the damping force generation mechanism smoothly. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a buffer according to a first embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the damping force generation mechanism of a shock absorber according to the first embodiment of the present invention. [Figure 3] This is a cross-sectional view showing the configuration of the main part of a buffer according to the first embodiment of the present invention. [Figure 4]This is a cross-sectional view showing the configuration of the main part of a buffer according to the first embodiment of the present invention. [Figure 5] This is a bottom view showing a pilot case of a buffer according to the first embodiment of the present invention. [Figure 6] This is a hydraulic circuit diagram showing the configuration of the main part of a shock absorber according to the first embodiment of the present invention. [Figure 7] This is a cross-sectional view showing the configuration of the main part of a buffer according to a second embodiment of the present invention. [Figure 8] This is a cross-sectional view showing the configuration of the main part of a buffer according to the third embodiment of the present invention. [Figure 9] This is a bottom view showing a pilot case of a buffer according to a third embodiment of the present invention. [Figure 10] This is a hydraulic circuit diagram showing the configuration of the main part of a shock absorber according to a third embodiment of the present invention. [Figure 11] This is a cross-sectional view showing another application example of the buffer configuration of the third embodiment according to the present invention. [Figure 12] This is a cross-sectional view showing the configuration of the main parts of another application example of the buffer configuration of the third embodiment of the present invention. [Modes for carrying out the invention]

[0010] [First Embodiment] The shock absorber of the first embodiment will be described below with reference to Figures 1 to 6. For the sake of explanation, in the following description, the upper side in Figures 1 to 4, 6 to 8, and 10 to 12 will be referred to as "upper," and the lower side in Figures 1 to 4, 6 to 8, and 10 to 12 will be referred to as "lower."

[0011] As shown in Figure 1, the shock absorber 1 is a twin-cylinder type hydraulic shock absorber. The shock absorber 1 is used in the suspension system of a vehicle. The shock absorber 1 has a cylinder 2 in which an oil liquid L is sealed as the working fluid. The cylinder 2 has an inner cylinder 3 and an outer cylinder 4. The inner cylinder 3 is cylindrical. The outer cylinder 4 is a bottomed cylinder. The inner diameter of the outer cylinder 4 is larger than the outer diameter of the inner cylinder 3. The inner cylinder 3 is located inside the outer cylinder 4. The central axis of the inner cylinder 3 and the central axis of the outer cylinder 4 coincide. There is a reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4.

[0012] 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 a bottomed cylinder. The bottom member 12 is fitted to 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. An attachment eye 13 is fixed to the bottom member 12 by welding on the outside, opposite to the body member 11 in its axial direction.

[0013] The shock absorber 1 is equipped with a piston 18. The piston 18 is slidably fitted into the inner cylinder 3 of the cylinder 2. The piston 18 divides the inner cylinder 3 into two chambers: an upper chamber 19 (first cylinder chamber) and a lower chamber 20 (second cylinder chamber). In the axial direction of the cylinder 2, the upper chamber 19 is 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 on the bottom member 12 side of the piston 18. Oil liquid L is sealed in the upper chamber 19 and the lower chamber 20 of the inner cylinder 3 as working fluid. Oil liquid L and gas G are sealed in the reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4 as working fluid.

[0014] The shock absorber 1 includes a piston rod 21. One end side of the piston rod 21 in its axial direction is disposed inside the inner cylinder 3 of the cylinder 2. The piston rod 21 is connected to the piston 18 at this one end. The other end side of the piston rod 21 in its axial direction, which is opposite to this one end, extends outside the cylinder 2 from the cylinder 2. The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 and the piston rod 21 move integrally. The stroke in which the piston rod 21 of the shock absorber 1 moves in the direction of increasing the protruding amount from the cylinder 2 is the extension stroke in which the overall length extends. The stroke in which the piston rod 21 of the shock absorber 1 moves in the direction of decreasing the protruding amount from the cylinder 2 is the contraction stroke in which the overall length contracts. The piston 18 of the shock absorber 1 moves toward the upper chamber 19 side during the extension stroke. The piston 18 of the shock absorber 1 moves toward the lower chamber 20 side during the contraction stroke.

[0015] A rod guide 22 is fitted on the upper end opening side of the inner cylinder 3 and on the upper end opening side of the outer cylinder 4. A seal member 23 is fitted on the outer cylinder 4 above the rod guide 22. A disk 24 is fitted on the outer cylinder 4 above the seal member 23. Both the rod guide 22 and the seal member 23 are annular. The disk 24 is a perforated circular flat plate with a certain thickness. The disk 24 abuts on the outer peripheral side portion of the seal member 23. The piston rod 21 slides along their axial directions with respect to the rod guide 22 and the seal member 23 respectively. The piston rod 21 extends from the inside of the cylinder 2 to the outside of the cylinder 2 beyond the seal member 23.

[0016] The rod guide 22 restricts the piston rod 21 from moving radially with respect to the inner cylinder 3 and the outer cylinder 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. Thereby, the central axis of the piston rod 21 coincides with the central axis of the cylinder 2. The rod guide 22 supports the piston rod 21 so as to be movable in the axial direction of the piston rod 21. The seal member 23 has its outer peripheral portion in close contact with the outer cylinder 4. The seal member 23 has its inner peripheral portion in close contact with the outer peripheral portion of the piston rod 21. The piston rod 21 moves in the axial direction of the seal member 23 with respect to the seal member 23. The seal member 23 suppresses leakage of the oil fluid L in the inner cylinder 3, the high-pressure gas and the oil fluid L in the reservoir chamber 6 to the outside.

[0017] The rod guide 22 has a larger outer diameter at its upper part than at its lower part. The rod guide 22 is fitted into the inner peripheral portion of the upper end of the inner cylinder 3 at its lower part with a smaller diameter. The rod guide 22 is fitted into the inner peripheral portion of the upper part of the outer cylinder 4 at its upper part with a larger diameter. A base valve 25 is installed on the bottom member 12 of the outer cylinder 4. The base valve 25 is positioned radially with respect to the outer cylinder 4. The base valve 25 partitions the lower chamber 20 and the reservoir chamber 6. The inner peripheral portion of the lower end of the inner cylinder 3 is fitted into the base valve 25. The upper end portion of the outer cylinder 4 is caulked inward in the radial direction of the outer cylinder 4. The seal member 23 is fixed to the cylinder 2 by being sandwiched between this caulked portion and the rod guide 22 together with the disk 24.

[0018] 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 the outer diameter of the main shaft portion 27. The mounting shaft portion 28 is disposed inside the cylinder 2. The piston 18 is attached to the mounting shaft portion 28 of the piston rod 21. The piston rod 21 has the main shaft portion 27 sliding with respect to the rod guide 22 and the seal member 23. The main shaft portion 27 has a shaft step portion 29. The shaft step portion 29 is provided at the end of the main shaft portion 27 on the side of the mounting shaft portion 28. The shaft step portion 29 extends in a direction orthogonal to the central axis of the piston rod 21.

[0019] The piston rod 21 has passage grooves 30 formed on the outer circumference of the mounting shaft portion 28. The passage grooves 30 are formed by cutting out the outer circumference of the mounting shaft portion 28 with a plane parallel to the central axis of the mounting shaft portion 28. The passage grooves 30 extend in the axial direction of the mounting shaft portion 28. Multiple passage grooves 30 are formed at equal intervals in the circumferential direction of the mounting shaft portion 28, specifically in two locations. The mounting shaft portion 28 has male threads 31 formed on the outer circumference of the end opposite to the main shaft portion 27 in the axial direction of the mounting shaft portion 28, where the passage grooves 30 are located.

[0020] 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 has a mounting eye 13 on the cylinder 2 side positioned at the bottom and connected to the vehicle's wheel side. If the shock absorber 1 is a single-tube type instead of a twin-tube type, the opposite may be true, 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.

[0021] In a vehicle, the wheels vibrate relative to the vehicle body as it moves. As a result, the relative positions of the cylinder 2 and piston rod 21 in the shock absorber 1 change in response to this vibration. This change is suppressed by the fluid resistance of the flow path provided in the shock absorber 1. As explained below, the fluid resistance of the flow path in the shock absorber 1 is designed to vary depending on the speed and amplitude of the vibration. By suppressing vibrations, the shock absorber 1 improves the ride comfort of the vehicle.

[0022] Furthermore, in a vehicle, in addition to vibrations generated by the wheels relative to the vehicle body, inertial forces and centrifugal forces generated in the vehicle body as it moves also act between the cylinder 2 and the piston rod 21. For example, a change in the direction of travel due to steering wheel operation generates centrifugal force in the vehicle body. Then, a force based on this centrifugal force acts between the cylinder 2 and the piston rod 21. As will be explained below, the shock absorber 1 has good characteristics against vibrations caused by forces generated in the vehicle body as it moves. The shock absorber 1 provides the vehicle with high driving stability.

[0023] The shock absorber 1 has a damping force generating mechanism 33. The damping force generating mechanism 33 includes a piston 18 and has the configuration shown in Figure 2.

[0024] The piston 18 has a piston body 35 and a sliding member 36. The piston body 35 is made of metal and is annular in shape. The piston body 35 of the piston 18 is fitted onto the mounting shaft portion 28 of the piston rod 21. The sliding member 36 is made of synthetic resin and is annular in shape. The sliding member 36 is integrally mounted on the outer circumferential surface of the piston body 35. The piston 18 slides against the inner cylinder 3 with the sliding member 36 in contact with the inner cylinder 3.

[0025] The piston body 35 is provided with passage holes 37, passage grooves 38, passage holes 39, and passage grooves 40. The passage holes 37 penetrate the piston body 35 in the axial direction. Multiple passage holes 37 are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35. The passage holes 39 penetrate the piston body 35 in the axial direction of the piston body 35. Multiple passage holes 39 are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35. In the piston body 35, passage holes 37 and passage holes 39 are formed alternately at equal pitches, one at a time, in the circumferential direction of the piston body 35.

[0026] 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 the end of the piston body 35 on the lower chamber 20 side in the axial direction. All passage holes 37 open into the passage groove 38 at this end side 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 end of the piston body 35 on the upper chamber 19 side, opposite to the passage groove 38 in the axial direction. All passage holes 39 open into the passage groove 40 at the end side of the piston body 35 opposite to the passage groove 38 in the axial direction. Multiple passage holes 37 open outward from the passage groove 40 in the radial direction of the piston body 35 at the end of the piston body 35 opposite to the passage groove 38 in the axial direction of the piston body 35. The multiple passage holes 39 have ends on the opposite side of the passage groove 40 in the axial direction of the piston body 35 that open outward from the passage groove 38 in the radial direction of the piston body 35. The piston 18 has a piston-side passage 43 between the inside of the multiple passage holes 37 and the inside of the passage groove 38. The piston 18 has a piston-side passage 44 between the inside of the multiple passage holes 39 and the inside of the passage groove 40.

[0027] The damping force generating mechanism 33 has a first valve mechanism 41 (valve mechanism) provided in the piston-side passage 43. The first valve mechanism 41 generates damping force by opening and closing the piston-side passage 43. The first valve mechanism 41 is located on the lower chamber 20 side in the axial direction of the piston 18. As a result, during the extension stroke, the piston-side passage 43 allows oil liquid L to flow from one upper chamber 19 to the other lower chamber 20 through the open first valve mechanism 41 as the piston 18 moves in one direction toward the upper chamber 19. The first valve mechanism 41 generates damping force by suppressing the flow of oil liquid L from the piston-side passage 43 to the lower chamber 20 that occurs at this time.

[0028] The damping force generating mechanism 33 has a first valve mechanism 42 provided in the piston-side passage 44. The first valve mechanism 42 generates damping force by opening and closing the piston-side passage 44. The first valve mechanism 42 is located on the upper chamber 19 side in the axial direction of the piston 18. As a result, during the compression stroke, the piston-side passage 44 allows oil liquid L to flow from the lower chamber 20 to the upper chamber 19 through the open first valve mechanism 42 as the piston 18 moves toward the lower chamber 20. The first valve mechanism 42 generates damping force by suppressing the flow of oil liquid L from the piston-side passage 44 to the upper chamber 19 that occurs at this time.

[0029] The piston body 35 is a perforated disc shape, and the mounting shaft portion 28 of the piston rod 21 is fitted into its inner circumference.

[0030] The piston body 35 has a main body portion 50, an inner seat portion 51, a valve seat portion 53, an inner seat portion 55, and a valve seat portion 57. The main body portion 50 is located in the middle of the piston body 35 in the axial direction. The inner seat portion 51 and the valve seat portion 53 are located at the axial end of the piston body 35 on the lower chamber 20 side. The inner seat portion 55 and the valve seat portion 57 are located at the axial end of the piston body 35 on the upper chamber 19 side.

[0031] The inner seat portion 51 is annular in shape. The inner seat portion 51 is provided on the inner circumference side of the main body portion 50 and protrudes from the main body portion 50 toward the lower chamber 20 in the axial direction of the piston body 35.

[0032] The valve seat portion 53 is annular in shape. The valve seat portion 53 is positioned radially outward from the inner seat portion 51 of the piston body 35. The valve seat portion 53 protrudes from the main body portion 50 toward the lower chamber 20 in the axial direction of the piston body 35. The tip surface of the protruding side of the valve seat portion 53 is higher in the axial direction of the protrusion of the piston body 35 than the tip surface of the protruding side of the inner seat portion 51. The valve seat portion 53 is positioned radially outward from the opening of the passage groove 38 toward the lower chamber 20 of the piston body 35. The valve seat portion 53 constitutes part of the first valve mechanism 41.

[0033] The inner seat portion 55 is annular in shape. The inner seat portion 55 is located on the inner circumference side of the main body portion 50 and protrudes from the main body portion 50 toward the upper chamber 19 in the axial direction of the piston body 35.

[0034] The valve seat portion 57 is annular in shape. The valve seat portion 57 is positioned radially outward from the inner seat portion 55 of the piston body 35. The valve seat portion 57 protrudes from the main body portion 50 toward the upper chamber 19 in the axial direction of the piston body 35. The tip surface of the protruding side of the valve seat portion 57 is higher in the axial direction of the protrusion of the piston body 35 than the tip surface of the protruding side of the inner seat portion 55. The valve seat portion 57 is positioned radially outward from the opening of the passage groove 40 toward the upper chamber 19 of the piston body 35. The valve seat portion 57 constitutes a part of the first valve mechanism 42.

[0035] As shown in Figure 3, the damping force generating mechanism 33 has, in order from the inner seat portion 51 side in the axial direction of the piston 18, one disc 70, one disc 71, one first damping valve 72 (damping force generating member), one disc 73, multiple discs, specifically four discs 74, multiple discs, specifically three discs 75, one disc 76, one disc 77, one regulating disc 78 (regulating member), one disc 79, one pilot case 81 (biasing force generating member), a second damping valve 84 consisting of multiple discs, specifically three discs 83, one disc 85, one disc 86, and one annular member 87.

[0036] Furthermore, the damping force generating mechanism 33 has a disc 91 and a disc 92 between the regulating disc 78 and the pilot case 81. The discs 91 and 92 are arranged to surround the disc 79 on its radially outer side. Of the discs 91 and 92, disc 91 is located on the side of the regulating disc 78, and disc 92 is located on the opposite side from the regulating disc 78.

[0037] Discs 70, 71, 73-77, 79, 83, 85, 86, 91, 92, regulating disc 78, pilot case 81, and annular member 87 are all made of metal. Discs 70, 71, 73-77, 79, 83, 85, 86, 91, 92, and annular member 87 are all perforated circular flat plates of a certain thickness. Discs 70, 71, 73-77, 79, 83, 85, 86, 91, 92 are formed by press molding. The first damping valve 72, regulating disc 78, and pilot case 81 are all annular. Discs 70, 71, 73-77, 79, 83, 85, 86, the first damping valve 72, regulating disc 78, pilot case 81, and annular member 87 all have the mounting shaft portion 28 of the piston rod 21 fitted inside.

[0038] The piston 18, discs 70, 71, 73-77, 79, 83, first damping valve 72, regulating disc 78, and pilot case 81 cover the passage groove 30 of the piston rod 21, forming a pilot chamber 95 within the passage groove 30.

[0039] The pilot case 81 is a bottomed cylindrical shape. The pilot case 81 is formed as a single, seamless piece by sintering. The pilot case 81 has a bottom portion 101 and a cylindrical portion 102.

[0040] The bottom portion 101 is perforated and disc-shaped, and the mounting shaft portion 28 of the piston rod 21 is fitted into its inner circumference. The cylindrical portion 102 is cylindrical and extends from the outer circumference of the bottom portion 101 to one side along the axial direction of the bottom portion 101. The pilot case 81 has an opening 103 on the side of the cylindrical portion 102 opposite to the bottom portion 101 in the axial direction. In other words, the pilot case 81 is a bottomed cylinder with an opening 103 at one end in the axial direction.

[0041] The bottom portion 101 includes a bottom body portion 111, an inner seat portion 112, a valve seat portion 113, an outer seat portion 114, an inner seat portion 115, and an outer seat portion 116.

[0042] The bottom body portion 111 is a perforated disc shape, and the mounting shaft portion 28 of the piston rod 21 is fitted to its inner circumference. As shown in Figure 4, the bottom body portion 111 has a passage hole 121 that penetrates the bottom body portion 111 in the axial direction. As shown in Figure 5, the bottom body portion 111 has multiple passage holes 121, specifically four, that are provided at equal intervals in the circumferential direction of the bottom body portion 111.

[0043] As shown in Figures 3 and 4, the inner sheet portion 112 is formed on the inner circumference side of the bottom body portion 111. The inner sheet portion 112 is annular. The inner sheet portion 112 protrudes from the bottom body portion 111 in the axial direction of the bottom body portion 111 on the same side as the cylindrical portion 102. The inner sheet portion 112 has a passage groove 124 that penetrates the inner sheet portion 112 in the radial direction.

[0044] The valve seat portion 113 is formed continuously with the inner seat portion 112, extending outward from the inner seat portion 112 in the radial direction of the bottom body portion 111. The valve seat portion 113 is annular in shape. The valve seat portion 113 protrudes from the bottom body portion 111 on the same side as the inner seat portion 112 in the axial direction of the bottom body portion 111. In the axial direction of the pilot case 81, the height of the protruding tip surface of the valve seat portion 113 is lower than the height of the protruding tip surface of the inner seat portion 112, and is equal to the height of the groove bottom surface of the passage groove 124.

[0045] The outer seat portion 114 is formed inward from the cylindrical portion 102 in the radial direction of the bottom body portion 111 and is continuous with the cylindrical portion 102. The outer seat portion 114 is formed outward from the valve seat portion 113 in the radial direction of the bottom body portion 111, but is separated from the valve seat portion 113. The outer seat portion 114 is annular. The outer seat portion 114 protrudes from the bottom body portion 111 in the axial direction of the bottom body portion 111 on the same side as the inner seat portion 112 and the valve seat portion 113. In the axial direction of the pilot case 81, the height of the tip surface on the protruding side of the outer seat portion 114 is slightly lower than the height of the tip surface on the protruding side of the valve seat portion 113.

[0046] The bottom portion 101 has an annular recess 125 formed by the bottom body portion 111, the valve seat portion 113, and the outer seat portion 114, which recesses from the axial direction of the cylindrical portion 102 toward the opposite side of the cylindrical portion 102. The annular recess 125 is an annular shape extending in the circumferential direction of the bottom portion 101. The annular recess 125 is recessed toward the opposite side of the cylindrical portion 102 along the axial direction of the pilot case 81, from the protruding end surface of the valve seat portion 113 and the protruding end surface of the outer seat portion 114. The bottom surface of the annular recess 125 is formed by the bottom body portion 111. The passage hole 121 is formed between the valve seat portion 113 and the outer seat portion 114 in the radial direction of the bottom body portion 111 and opens to the bottom surface of the annular recess 125.

[0047] The inner sheet portion 115 is formed on the inner circumference side of the bottom body portion 111. The inner sheet portion 115 is annular in shape. The inner sheet portion 115 protrudes from the inner circumference side of the bottom body portion 111 in the axial direction of the bottom body portion 111, on the opposite side from the inner sheet portion 112. As shown in Figure 3, the inner sheet portion 115 has passage grooves 132 that penetrate the inner sheet portion 115 in the radial direction. As shown in Figure 5, the inner sheet portion 115 has multiple passage grooves 132, specifically four, that are provided at equal intervals in the circumferential direction of the inner sheet portion 115.

[0048] The outer sheet portion 116 is formed radially outward from the inner sheet portion 115 in the bottom body portion 111. As shown in Figure 3, the outer sheet portion 116 protrudes radially outward from the inner sheet portion 115 and in the axial direction of the bottom body portion 111 on the same side as the inner sheet portion 115. As shown in Figure 5, the outer sheet portion 116 is a non-circular, petal-shaped irregular sheet. The outer sheet portion 116 has multiple, specifically four, sheet components 133. These sheet components 133 are identical in shape and are arranged at equal intervals in the circumferential direction of the pilot case 81. The multiple sheet components 133 extend radially from the inner sheet portion 115. As shown in Figure 3, in the axial direction of the pilot case 81, the position of the tip surface of the multiple sheet components 133 opposite to the bottom body portion 111 is equivalent to the position of the tip surface of the inner sheet portion 115 opposite to the bottom body portion 111.

[0049] A passage recess 134 is formed inside each sheet component 133. As shown in Figure 5, the passage recess 134 is formed by being surrounded by a part of the inner sheet portion 115 and the sheet component 133. As shown in Figure 3, the passage recess 134 is recessed along the axial direction of the pilot case 81 from the protruding end surface of the inner sheet portion 115 and the protruding end surface of the sheet component 133. The bottom surface of the passage recess 134 is formed by the bottom body portion 111. As shown in Figure 5, passage recesses 134 are formed inside all sheet components 133. In the circumferential direction of the pilot case 81, each of the passage recesses 134 and the passage groove 132 of the inner sheet portion 115 are in phase. The passage groove 132 is provided in the inner sheet portion 115 so as to open to the inside of each of the passage recesses 134.

[0050] The passage holes 121 are located between adjacent seat components 133 in the circumferential direction of the pilot case 81. Therefore, the passage holes 121 are located outside the outer seat portion 116. The pilot case 81 has four sections between adjacent seat components 133 in its circumferential direction, and each of these four sections is provided with a passage hole 121.

[0051] The disc 70 shown in Figures 3 and 4 has a constant outer diameter around its entire circumference. The outer diameter of the disc 70 is larger than the outer diameter of the inner seat portion 51 of the piston 18. A notch 141 is formed in the disc 70. The notch 141 extends radially outward from the inner peripheral edge that fits onto the mounting shaft portion 28 of the disc 70. The notch 141 penetrates the disc 70 in the axial direction of the disc 70. The notch 141 of the disc 70, together with the piston 18 and the disc 71, constitutes an introduction orifice 142.

[0052] The disk 71 has a constant outer diameter around its entire circumference, and its inner diameter is also constant around its entire circumference. The outer diameter of disk 71 is smaller than that of disk 70. Disk 71 is located inside the outer end position of the notch 141 in the radial direction of disk 70, and the introduction orifice 142 is formed by disk 71 and the notch 141.

[0053] The first damping valve 72 consists of a disc 151 and a sealing member 152. The disc 151 is made of metal and is a perforated, circular flat plate of uniform thickness. The disc 151 is formed by press molding. The outer diameter of the disc 151 is constant around its entire circumference, and its inner diameter is also constant around its entire circumference. The outer diameter of the disc 151 is larger than the outer diameter of the valve seat portion 53 of the piston 18. The mounting shaft portion 28 of the piston rod 21 is fitted to the inner circumference side of the disc 151. In the first damping valve 72, the disc 151 is in contact with the valve seat portion 53.

[0054] The passage within the introduction orifice 142 of disk 70 is in constant communication with the piston-side passage 43 and the pilot chamber 95.

[0055] The first damping valve 72 opens and closes the opening on the lower chamber 20 side of the piston-side passage 43 shown in Figure 3, which is formed in the piston 18, by the disc 151 moving apart from and in contact with the valve seat portion 53.

[0056] The sealing member 152 is made of an elastic material with sealing properties, specifically rubber. The sealing member 152 is annular in shape. The sealing member 152 is fixed to the outer circumference of the disc 151. The sealing member 152 fits around the entire circumference of the inner surface of the cylindrical portion 102 of the pilot case 81 on the opening 103 side. The sealing member 152 is axially slidable relative to the inner surface of the cylindrical portion 102. The sealing member 152 constantly seals the gap between the first damping valve 72 and the cylindrical portion 102. The pilot case 81 has the first damping valve 72 positioned in its opening 103.

[0057] The outer diameter of disc 73 is constant throughout its entire circumference, and its inner diameter is also constant throughout its entire circumference. The outer diameter of disc 73 is smaller than the minimum inner diameter of the sealing member 152. The outer diameter of disc 73 is equal to the outer diameter of disc 70.

[0058] The outer diameter of disc 74 is constant throughout its entire circumference, and its inner diameter is also constant throughout its entire circumference. The outer diameter of disc 74 is smaller than the outer diameter of disc 73. The outer diameter of disc 74 is the same as the outer diameter of disc 71.

[0059] Disc 75 has a constant outer diameter and a constant inner diameter throughout its entire circumference. The outer diameter of Disc 75 is larger than that of Disc 73 and larger than that of Disc 74.

[0060] The outer diameter of disc 76 is constant throughout its entire circumference, and its inner diameter is also constant throughout its entire circumference. The outer diameter of disc 76 is larger than the outer diameter of disc 75.

[0061] The inner diameter of the disc 77 is constant around its entire circumference. The outer diameter of the disc 77 is the same as the outer diameter of the disc 76. A notch 155 is formed in the disc 77. The notch 155 extends radially inward from the outer edge of the disc 77. The notch 155 penetrates the disc 77 in the axial direction. The inner portion of the notch 155 in the radial direction of the disc 77 is arc-shaped and extends longer in the circumferential direction of the disc 77, with the inner portion being longer in the circumferential direction than the outer portion being longer in the radial direction of the disc 77. Multiple notches 155 are provided on the disc 77 at equal intervals in the circumferential direction of the disc 77.

[0062] The restrictor disc 78 has a disc 161 on the side of disc 77 and a disc 162 on the opposite side of disc 77 in the axial direction of the restrictor disc 78. Both disc 161 and disc 162 are made of metal and are perforated circular flat plates of a certain thickness. Both disc 161 and disc 162 are formed by press molding.

[0063] The disc 161 has a constant outer diameter and a constant inner diameter throughout its entire circumference. The outer diameter of the disc 161 is larger than the outer diameter of discs 76 and 77, and smaller than the inner diameter of the cylindrical portion 102 of the pilot case 81. The mounting shaft portion 28 of the piston rod 21 is fitted to the inner circumference of the disc 161. The disc 161 has a through hole 165 that penetrates the disc 161 in the axial direction. The through hole 165 is in the shape of a long arc extending in the circumferential direction of the disc 161. The through hole 165 aligns the radial position of the disc 77 and 161 with the radial inner portion of the notch 155 of the disc 77, which is in the shape of a long arc extending in the circumferential direction of the disc 77. Multiple through holes 165 are provided on the disc 161 at equal intervals in the circumferential direction of the disc 161. The passage within the through-hole 165 communicates with the passage within the notch 155 of the disc 77. The notch 155 of the disc 77 and the through-hole 165 of the disc 161 constitute a communicating orifice 166 (second throttling mechanism).

[0064] The disc 162 has a constant outer diameter and a constant inner diameter throughout its entire circumference. The outer diameter of the disc 162 is slightly larger than the outer diameter of the disc 161 and smaller than the inner diameter of the cylindrical portion 102 of the pilot case 81. The inner diameter of the disc 162 is larger than the inner diameter of the disc 161 and larger than the outer diameter of the valve seat portion 113 of the pilot case 81. The disc 162 is arranged coaxially with the disc 161 and is located outside the through hole 165 in the radial direction of the disc 161. The disc 162 is integrated with the disc 161 by ring welding to the disc 161.

[0065] The disc 79 has a constant outer diameter and a constant inner diameter throughout its entire circumference. The outer diameter of the disc 79 is smaller than the inner diameter of the disc 162 of the regulating disc 78. The disc 79 is positioned inside the radial through hole 165 of the regulating disc 78. The outer diameter of the disc 79 is equivalent to the outer diameter of the inner seat portion 112 of the pilot case 81.

[0066] The disc 83 has a constant outer diameter and a constant inner diameter throughout its entire circumference. The outer diameter of the disc 83 is equivalent to the outer diameter of the outer seat portion 116 of the pilot case 81.

[0067] The outer diameter of disc 85 is constant throughout its entire circumference, and its inner diameter is also constant throughout its entire circumference. The outer diameter of disc 85 is smaller than the outer diameter of disc 83.

[0068] The outer diameter of disc 86 is constant throughout its entire circumference, and its inner diameter is also constant throughout its entire circumference. The outer diameter of disc 86 is smaller than the outer diameter of disc 85. The outer diameter of disc 86 is equal to the outer diameter of the inner seat portion 115 of the pilot case 81.

[0069] The annular member 87 has a constant outer diameter and a constant inner diameter throughout its entire circumference. The annular member 87 has an outer diameter that is larger than the outer diameter of disc 85 and smaller than the outer diameter of disc 83. The annular member 87 is thicker than the thickness of discs 83 and 85 and has higher rigidity than disc 83.

[0070] The outer diameter of the disc 91 is constant around its entire circumference. The outer diameter of the disc 91 is slightly larger than the outer diameter of the disc 162 of the regulating disc 78, and slightly smaller than the inner diameter of the cylindrical portion 102 of the pilot case 81. The inner diameter of the disc 91 is smaller than the outer diameter of the valve seat portion 113 of the pilot case 81, and larger than the outer diameter of the inner seat portion 112 of the valve seat portion 113 and the disc 79. A notch 171 is formed on the inner circumference of the disc 91. The notch 171 extends radially outward from the inner peripheral edge of the disc 91. The notch 171 penetrates the disc 91 in the axial direction.

[0071] The outer diameter of disc 92 is constant around its entire circumference, and its inner diameter is also constant around its entire circumference. The outer diameter of disc 92 is the same as the outer diameter of disc 91, and its inner diameter is the same as the inner diameter of disc 91. The outer diameter of disc 92 is larger than the inner diameter of the outer seat portion 114 of the pilot case 81.

[0072] The restricting disc 78 presses the outer circumferences of discs 91 and 92 against the outer seat portion 114 of the pilot case 81. At this time, disc 162 of the restricting disc 78 comes into contact with the outer circumference of disc 91, and the outer circumference of disc 92 comes into contact with the outer seat portion 114. The restricting disc 78, together with discs 75 to 77, restricts the outer circumferences of discs 91 and 92 from moving axially away from the outer seat portion 114 of the pilot case 81, i.e., preventing the valve from opening.

[0073] As described above, in the axial direction of the pilot case 81, the outer seat portion 114 has a lower protruding height than the valve seat portion 113. Therefore, when discs 91 and 92 are pressed against the outer seat portion 114 by the regulating disc 78, they elastically deform in the axial direction so that their inner circumference is located closer to disc 161 of the regulating disc 78 than their outer circumference, and their inner circumference is pressed against the valve seat portion 113. At that time, disc 92 comes into contact with the valve seat portion 113 over its entire circumference.

[0074] The area enclosed by the first damping valve 72, discs 73-77, regulating disc 78, and pilot case 81 constitutes the main back pressure chamber 181. The area enclosed by the regulating disc 78 and discs 91 and 92 constitutes the sub-back pressure chamber 182. The through hole 165 opens into the sub-back pressure chamber 182. The area enclosed by the annular recess 125 of the pilot case 81 and disc 92 constitutes the variable chamber 183.

[0075] A communication orifice 166 is provided between the main back pressure chamber 181 and the sub back pressure chamber 182, consisting of the notch 155 in the disk 77 and the through hole 165 in the disk 161. In other words, the sub back pressure chamber 182 is connected to the main back pressure chamber 181 via a passage within the communication orifice 166.

[0076] As shown in Figure 4, the variable chamber 183 communicates with the lower chamber 20 via a passage in the passage hole 121 of the pilot case 81. The volume of the variable chamber 183 is variable depending on the deformation of the disks 91 and 92. Specifically, when the disks 91 and 92 deform so that they move closer to the bottom surface of the annular recess 125, the volume of the variable chamber 183 decreases, thereby increasing the volume of the sub-back pressure chamber 182. When the disks 91 and 92 deform from this state so that they move away from the bottom surface of the annular recess 125, the volume of the variable chamber 183 increases, thereby decreasing the volume of the sub-back pressure chamber 182.

[0077] The main back pressure chamber 181, the communicating orifice 166, and the sub-back pressure chamber 182 constitute the back pressure chamber 184. The bottomed cylindrical pilot case 81, together with the first damping valve 72 located on the opening 103 side, forms the back pressure chamber 184.

[0078] When the pressure in the sub-back pressure chamber 182 is greater than or equal to the pressure in the variable chamber 183, disc 92 of discs 91 and 92 contacts the valve seat portion 113 around its entire circumference. As a result, discs 91 and 92 and the valve seat portion 113 restrict the flow of oil L from the pilot chamber 95 and the sub-back pressure chamber 182 to the variable chamber 183. When the pressure in the variable chamber 183 is higher than the pressure in the sub-back pressure chamber 182, discs 91 and 92 separate from the valve seat portion 113. As a result, discs 91 and 92 and the valve seat portion 113 allow the flow of oil L from the variable chamber 183 to the pilot chamber 95 and the sub-back pressure chamber 182. Therefore, the discs 91 and 92 and the valve seat portion 113 constitute a check valve 191 that restricts the flow of oil L from the pilot chamber 95 and sub-back pressure chamber 182 to the variable chamber 183, while allowing the flow of oil L from the variable chamber 183 to the pilot chamber 95 and sub-back pressure chamber 182.

[0079] Discs 91 and 92 deform and move almost as a single unit while overlapping. Discs 91 and 92 constitute the movable valve 192 (movable member) of the check valve 191. The valve 192 is located at the bottom 101 of the pilot case 81 and defines a variable chamber 183 on the opposite side of the back pressure chamber 184, thereby blocking the flow of oil L from the back pressure chamber 184 to the variable chamber 183.

[0080] When the check valve 191 opens, the inner circumferential portion of the deformed valve 192 approaches the disc 161 of the regulating disc 78, narrowing the flow path between them. The inner circumferential portion of the valve 192 and the disc 161 of the regulating disc 78 constitute a variable orifice 193 (first throttling mechanism, first throttling section). The flow path cross-sectional area of ​​the variable orifice 193 is smaller than that of the communication orifice 166. The variable orifice 193 is provided between the pilot chamber 95 and the sub-back pressure chamber 182, and changes the cross-sectional area of ​​the flow path between the pilot chamber 95 and the sub-back pressure chamber 182 according to the amount of deformation of the valve 192. That is, the larger the amount of deformation of the valve 192, the narrower the flow path between the pilot chamber 95 and the sub-back pressure chamber 182 becomes. The variable orifice 193 includes a passage within the notch 171 of the disc 91. The passage within the notch 171 of the disc 91 makes the flow path cross-sectional area within the variable orifice 193 a non-zero minimum value when the disc 91 of the valve 192 contacts the disc 161 of the regulating disc 78. In this way, the valve 192 constitutes a variable orifice 193 that restricts the inflow of oil liquid L from the variable chamber 183 to the sub-back pressure chamber 182. The valve 192 also functions as a check valve 191. The sub-back pressure chamber 182 is provided between the variable orifice 193 and the main back pressure chamber 181.

[0081] The disc 151 of the first damping valve 72 seats on the valve seat portion 53 of the piston 18. When the first damping valve 72 dissipates from the valve seat portion 53 of the piston 18, it causes the oil liquid L to flow from the piston-side passage 43 shown in Figure 3 through the passage between the disc 151 and the valve seat portion 53 from the upper chamber 19 to the lower chamber 20. The piston-side passage 43 and the passage between the disc 151 and the valve seat portion 53 constitute a first passage 201 that connects the upper chamber 19 and the lower chamber 20 shown in Figure 2. The first damping valve 72 is provided in this first passage 201 and generates a damping force by suppressing the flow of oil liquid L caused by the sliding of the piston 18 toward the extension side. The first damping valve 72, together with the valve seat portion 53 of the piston 18, constitutes a first valve mechanism 41. The first valve mechanism 41 acts to open when the upper chamber 19 is under upstream pressure, thereby suppressing the flow of oil liquid L. The first passage 201 is the extension-side passage through which the working fluid, oil L, flows from one upper chamber 19 to the other lower chamber 20 during the extension stroke of the piston 18 toward the upper chamber 19. The extension-side first valve mechanism 41, consisting of a valve seat portion 53 and a first damping valve 72, is provided in the first passage 201, and generates a damping force by opening and closing this first passage 201 with the first damping valve 72 to suppress the flow of oil L. The damping force of the first valve mechanism 41 can be adjusted by the pressure in the main back pressure chamber 181 of the back pressure chamber 184. The lower chamber 20 is downstream of the first damping valve 72 in the direction of the flow of oil L in the first passage 201 during the extension stroke.

[0082] As shown in Figure 3, the second damping valve 84, which consists of multiple discs 83, has an outer diameter that is slightly larger than the maximum outer diameter of the tip surface of the outer seat portion 116. The second damping valve 84 can be seated on and off the outer seat portion 116.

[0083] The piston-side passage 43, the passage within the introduction orifice 142 of the disc 70, the pilot chamber 95 on the piston rod 21 side, the passage within the variable orifice 193, the back pressure chamber 184, and the passage between the second damping valve 84 and the outer seat portion 116 when the valve is open constitute the second passage 202 that connects the upper chamber 19 and the lower chamber 20 shown in Figure 2.

[0084] The second passage 202 is provided in parallel with the first passage 201, except for the piston-side passage 43 which is common with the first passage 201, and is capable of connecting the upper chamber 19 and the lower chamber 20. The second passage 202 is provided with an introduction orifice 142, a pilot chamber 95, a variable orifice 193, a sub-back pressure chamber 182, a communication orifice 166, and a main back pressure chamber 181, as shown in Figure 3.

[0085] The outer seat portion 116 and the second damping valve 84 constitute a second valve mechanism 205 provided in the second passage 202, which opens and closes the second passage 202. The second damping valve 84 of the second valve mechanism 205 is seated on the outer seat portion 116. During the extension stroke, the second damping valve 84 opens, providing resistance to the flow of oil L from the upper chamber 19 to the lower chamber 20 through the second passage 202. In other words, the second valve mechanism 205 generates a damping force by suppressing the flow of oil L from the upper chamber 19 to the lower chamber 20. The second valve mechanism 205 is an extension-side damping force generating mechanism provided in the second passage 202, which generates a damping force by the flow of oil L.

[0086] The back pressure chamber 184 applies internal pressure to the first damping valve 72 in the direction of the piston 18, that is, in the valve closing direction, causing the disc 151 to seat on the valve seat portion 53. The pilot case 81 is a bottomed cylindrical shape and forms a back pressure chamber 184 that generates a biasing force in the valve closing direction on the first damping valve 72, which is located on the opening 103 side. In other words, the back pressure chamber 184 generates a biasing force in the valve closing direction on the first damping valve 72 that causes it to contact the valve seat portion 53 of the piston 18.

[0087] As shown in Figure 4, the passage hole 121 provided in the bottom 101 of the pilot case 81 constitutes a lower chamber connecting passage 211 that connects the variable chamber 183 and the lower chamber 20. The lower chamber connecting passage 211 discharges the oil liquid L from the variable chamber 183 into the lower chamber 20 when the volume of the variable chamber 183 is reduced by the valve 192. The variable chamber 183 and the lower chamber connecting passage 211 also constitute a second passage 202.

[0088] The valve 192 of the check valve 191 is provided to open and close between the lower chamber communication passage 211 and the variable chamber 183 and the back pressure chamber 184 and the pilot chamber 95. When the valve 192 of the check valve 191 is in contact with the valve seat portion 113 of the pilot case 81, it blocks the flow of oil L between the back pressure chamber 184 and the pilot chamber 95 and the variable chamber 183, the lower chamber communication passage 211 and the lower chamber 20. When the valve 192 of the check valve 191 is separated from the valve seat portion 113, it allows the flow of oil L between the lower chamber 20, the lower chamber communication passage 211 and the variable chamber 183 and the back pressure chamber 184 and the pilot chamber 95.

[0089] Here, when the pressure on the variable chamber 183, lower chamber connecting passage 211, and lower chamber 20 side becomes higher than a predetermined value or more than the pressure on the back pressure chamber 184 and pilot chamber 95 side, the valve 192 of the check valve 191 allows the flow of oil L from the lower chamber 20 to the back pressure chamber 184 and pilot chamber 95 via the lower chamber connecting passage 211 and variable chamber 183. When the pressure on the back pressure chamber 184 and pilot chamber 95 side is equal to or higher than the pressure on the variable chamber 183, lower chamber connecting passage 211, and lower chamber 20 side, the valve 192 of the check valve 191 restricts the flow of oil L from the back pressure chamber 184 and pilot chamber 95 to the lower chamber 20 via the variable chamber 183 and lower chamber connecting passage 211. In other words, the check valve 191 restricts the flow of oil L in one direction from the back pressure chamber 184 and pilot chamber 95 to the lower chamber 20 between the back pressure chamber 184 and pilot chamber 95 and the lower chamber 20. On the other hand, the check valve 191 allows the flow of oil L in the other direction from the lower chamber 20 to the back pressure chamber 184 and pilot chamber 95. The valve 192 of the check valve 191 is the valve member of the check valve 191.

[0090] The check valve 191 restricts the flow of oil L from the upper chamber 19 shown in Figure 2, the piston-side passage 43, the passage in the introduction orifice 142 of the disc 70 shown in Figure 3, the pilot chamber 95, and the back pressure chamber 184 to the variable chamber 183 shown in Figure 4, the lower chamber connecting passage 211, and the lower chamber 20. The check valve 191 allows the flow of oil L from the lower chamber 20, the lower chamber connecting passage 211, and the variable chamber 183 to the upper chamber 19 via the back pressure chamber 184, the pilot chamber 95, the passage in the introduction orifice 142 of the disc 70, and the piston-side passage 43 shown in Figure 2.

[0091] The first valve mechanism 42 on the compression side has, in order from the inner seat portion 55 side in the axial direction of the piston 18, one disc 221, one disc 222, multiple discs, specifically three discs 223, one disc 224, one disc 225, and one annular member 226. The discs 221-225 and the annular member 226 are made of metal and are perforated circular flat plates of a certain thickness. The discs 221-225 are formed by press molding. The mounting shaft portion 28 of the piston rod 21 is fitted inside each of the discs 221-225 and the annular member 226.

[0092] The disc 221 has an outer diameter equivalent to the outer diameter of the inner seat portion 55 of the piston 18. Disc 222 has a slightly larger outer diameter than disc 221. Multiple discs 223 constitute the first damping valve 231. The outer diameter of the first damping valve 231 is slightly larger than the outer diameter of the valve seat portion 57 of the piston 18.

[0093] Disk 224 has an outer diameter smaller than the combined outer diameter of multiple disks 223, but the same as the outer diameter of disk 221. Disc 225 has a larger outer diameter than Disc 224. The annular member 226 has an outer diameter that is larger than the outer diameter of the disc 225 and smaller than the outer diameter of the disc 223. The annular member 226 is thicker and more rigid than the disc 223. The annular member 226 is in contact with the axial step portion 29 of the piston rod 21. The disc 225 and the annular member 226 suppress deformation of the first damping valve 231 in the opening direction that exceeds a specified limit.

[0094] The first damping valve 231, consisting of multiple discs 223, forms the first valve mechanism 42 together with the valve seat portion 57 of the piston 18. The first damping valve 231 opens by separating from the valve seat portion 57. When this occurs, the first damping valve 231 allows the oil L from the piston-side passage 44 to flow into the upper chamber 19 through the space between it and the valve seat portion 57. The piston-side passage 44 and the passage between the first damping valve 231 and the valve seat portion 57 become the first compression-side passage 232 through which the oil L in the lower chamber 20 flows as the piston 18 moves toward the lower chamber 20. In the compression stroke, the oil L, acting as the working fluid, flows out of the first passage 232 from one lower chamber 20 toward the other upper chamber 19. The first compression-side valve mechanism 42, consisting of the valve seat portion 57 and the first damping valve 231, is provided in the first passage 232. The first valve mechanism 42 generates a damping force by opening and closing the first passage 232 with the first damping valve 231 to suppress the flow of the oil liquid L.

[0095] As shown in Figure 6, the shock absorber 1 is provided with a fixed orifice 235. The fixed orifice 235 keeps the upper chamber 19 and the lower chamber 20 in constant communication via the piston 18 shown in Figure 2. The fixed orifice 235 is formed, for example, by cutting out at least one of the valve seat portion 57 of the compression-side first valve mechanism 42 and the first damping valve 231. The fixed orifice 235 can also be formed by cutting out the valve seat portion 53 of the extension-side first valve mechanism 41, and it is also possible to combine both the extension-side and compression-side orifices.

[0096] The pilot case 81 and valve 192 shown in Figure 4 constitute a frequency-sensitive mechanism 241 that varies the damping force in response to the reciprocating frequency of the piston 18 (hereinafter referred to as the piston frequency). The frequency-sensitive mechanism 241 consists of a portion that increases when the disk 92 deforms in the sub-back pressure chamber 182 so as to approach the bottom surface of the annular recess 125, a variable chamber 183, and a valve 192 that separates these. The frequency-sensitive mechanism 241 is an accumulator. The frequency-sensitive mechanism 241 is provided in the second passage 202, which includes the lower chamber communication passage 211. The valve 192 of the frequency-sensitive mechanism 241 moves and deforms in accordance with the reciprocating frequency of the piston 18, changing the volume of the back pressure chamber 184, which is always in communication with the upper chamber 19, and the volume of the variable chamber 183, which is always in communication with the lower chamber 20. The frequency-sensitive mechanism 241 has a valve 192 that is movably provided in the second passage 202, which includes the lower chamber connecting passage 211. The frequency-sensitive mechanism 241 varies the biasing force on the first damping valve 72 by the back pressure chamber 184.

[0097] During the extension stroke, the sub-back pressure chamber 182 side of the back pressure chamber 184 becomes more pressure than the variable chamber 183, the lower chamber connecting passage 211, and the lower chamber 20 side. As a result, the valve 192 deforms toward the bottom surface of the annular recess 125 in response to the pressure in the sub-back pressure chamber 182. This expands the volume of the back pressure chamber 184 and reduces the volume of the variable chamber 183. In this way, the frequency-sensitive mechanism 241 operates when the upper chamber 19 is under upstream pressure and acts to vary the damping force in response to the piston frequency. In other words, the frequency-sensitive mechanism 241 changes the volume of the variable chamber 183 due to the movement caused by the deformation of the valve 192 during the extension stroke, and as a result changes the volume of the back pressure chamber 184.

[0098] During the compression stroke, the pressure on the lower chamber 20, the lower chamber connecting passage 211, and the variable chamber 183 side becomes higher than that on the sub-back pressure chamber 182 side. As a result, the valve 192 separates from the valve seat portion 113 of the pilot case 81, and the oil liquid L flows from the lower chamber 20, the lower chamber connecting passage 211, and the variable chamber 183 to the sub-back pressure chamber 182 and the pilot chamber 95. In other words, when the lower chamber 20 is at upstream pressure, the check valve 191 provided in the second passage 202, which includes the lower chamber connecting passage 211, opens and acts to allow the oil liquid L to flow.

[0099] During the compression stroke, when the valve 192 of the check valve 191 separates from the valve seat portion 113, the valve 192 narrows the flow path cross-sectional area of ​​the passage in the variable orifice 193 between the valve 192 and the disc 161 of the regulating disc 78. This acts to suppress the flow of oil L from the lower chamber 20 to the sub-back pressure chamber 182 via the lower chamber connecting passage 211, the variable chamber 183, and the open check valve 191. As a result, the pressure rise in the sub-back pressure chamber 182 is suppressed. Furthermore, since a communication orifice 166 is also provided between the sub-back pressure chamber 182 and the main back pressure chamber 181, the communication orifice 166 acts to suppress the flow of oil L from the sub-back pressure chamber 182 to the main back pressure chamber 181. As a result, the pressure rise in the main back pressure chamber 181 is suppressed even more than the pressure rise in the sub-back pressure chamber 182. In this way, when the lower chamber 20 is under upstream pressure, the variable orifice 193 located downstream of the check valve 191 operates to suppress and control the flow of the working fluid, oil liquid L, to the sub-back pressure chamber 182 and the main back pressure chamber 181.

[0100] The mounting shaft portion 28 is inserted through the inside of each piston rod 21, and the following are stacked on the shaft step portion 29 in this order: the annular member 226 shown in Figure 2, disc 225, disc 224, multiple discs 223, disc 222, disc 221, piston 18, disc 70, disc 71 shown in Figure 3, first damping valve 72, disc 73, multiple discs 74, multiple discs 75, disc 76, disc 77, regulating disc 78, and disc 79. Also, discs 91 and 92 are stacked on the regulating disc 78 in this order. In this state, the mounting shaft portion 28 is inserted through the inside of each, and the pilot case 81, multiple discs 83, disc 85, disc 86, and annular member 87 are stacked on disc 79 in this order.

[0101] With the components from the annular member 226 to the annular member 87 stacked in this manner, as shown in Figure 2, a nut 245 is screwed onto the male thread 31 of the mounting shaft portion 28 of the piston rod 21 that protrudes beyond the annular member 87. As a result, the components from the annular member 226 to the annular member 87, except for the discs 91 and 92 shown in Figures 3 and 4, are clamped axially by their inner circumferences or all of them between the axial step portion 29 of the piston rod 21 shown in Figure 2 and the nut 245.

[0102] In this state, as shown in Figures 3 and 4, the sealing member 152 of the first damping valve 72 is fitted into the cylindrical portion 102 of the pilot case 81, and the discs 73-77, 79, regulating disc 78, and discs 91, 92 are positioned inside the pilot case 81. The regulating disc 78 presses the outer circumference portion of discs 91, 92 against the outer seat portion 114 of the pilot case 81 so that axial movement is impossible, while the inner circumference portion of discs 91, 92 contacts the valve seat portion 113 of the pilot case 81. In this state, discs 91, 92 undergo slight elastic deformation and press against the valve seat portion 113.

[0103] As shown in Figure 1, the base valve 25 described above is provided between the inner cylinder 3 and the bottom member 12 of the outer cylinder 4. This base valve 25 has a base valve member 251, a disc valve 252, a disc valve 253, and a mounting pin 254. The base valve 25 is placed on the bottom member 12 by the base valve member 251 and is fitted into the inner cylinder 3 by the base valve member 251. The base valve member 251 separates the lower chamber 20 and the reservoir chamber 6. The disc valve 252 is provided on the lower side of the base valve member 251, i.e., the reservoir chamber 6 side. The disc valve 253 is provided on the upper side of the base valve member 251, i.e., the lower chamber 20 side. The mounting pin 254 attaches the disc valve 252 and the disc valve 253 to the base valve member 251.

[0104] The base valve member 251 is annular in shape, with a mounting pin 254 inserted through its radial center. The base valve member 251 has a plurality of passage holes 255 and a plurality of passage holes 256. The plurality of passage holes 255 allow oil liquid L to flow between the lower chamber 20 and the reservoir chamber 6. The plurality of passage holes 256 are located radially outward from the plurality of passage holes 255 of the base valve member 251. The plurality of passage holes 256 allow oil liquid L to flow between the lower chamber 20 and the reservoir chamber 6. The disc valve 252 on the reservoir chamber 6 side allows the flow of oil liquid L from the lower chamber 20 to the reservoir chamber 6 through the passage holes 255. On the other hand, the disc valve 252 suppresses the flow of oil liquid L from the reservoir chamber 6 to the lower chamber 20 through the passage holes 255. The disc valve 253 allows the flow of oil L from the reservoir chamber 6 to the lower chamber 20 through the passage hole 256. On the other hand, the disc valve 253 suppresses the flow of oil L from the lower chamber 20 to the reservoir chamber 6 through the passage hole 256.

[0105] The disc valve 252, together with the base valve member 251, constitutes a damping valve mechanism 257. The damping valve mechanism 257 opens during the compression stroke of the shock absorber 1, allowing oil L to flow from the lower chamber 20 to the reservoir chamber 6 and generating a damping force. The disc valve 253, together with the base valve member 251, constitutes a suction valve mechanism 258. The suction valve mechanism 258 opens during the extension stroke of the shock absorber 1, allowing oil L to flow from the reservoir chamber 6 into the lower chamber 20. The suction valve mechanism 258 primarily functions to compensate for the fluid shortage caused by the extension of the piston rod 21 from the cylinder 2 by allowing fluid to flow from the reservoir chamber 6 to the lower chamber 20 without substantially generating a damping force.

[0106] The configuration of the damping force generation mechanism 33 described above can be represented in a hydraulic circuit diagram as shown in Figure 6.

[0107] The damping force generating mechanism 33 has a fixed orifice 235 that keeps the upper chamber 19 and the lower chamber 20 in constant communication. The damping force generating mechanism 33 has a first passage 201 that connects the upper chamber 19 and the lower chamber 20, and a first valve mechanism 41 provided in the first passage 201. The damping force generating mechanism 33 has a second passage 202 that connects the upper chamber 19 and the lower chamber 20 in parallel with the first passage 201. The damping force generating mechanism 33 has an introduction orifice 142, a pilot chamber 95 on the lower chamber 20 side of the introduction orifice 142, and a check valve 191 on the lower chamber 20 side of the pilot chamber 95. The damping force generating mechanism 33 has a second valve mechanism 205 provided between the pilot chamber 95 and the lower chamber 20 in the second passage 202. The damping force generating mechanism 33 has a variable orifice 193 communicating with the pilot chamber 95, a sub-back pressure chamber 182 communicating with the variable orifice 193, a communication orifice 166 communicating with the sub-back pressure chamber 182, and a main back pressure chamber 181 communicating with the communication orifice 166 in the second passage 202. The damping force generating mechanism 33 has a frequency-sensitive mechanism 241 between the sub-back pressure chamber 182 and the lower chamber 20 in the second passage 202. In the damping force generating mechanism 33, the pressure in the main back pressure chamber 181 is applied as back pressure to the first valve mechanism 41. In the damping force generating mechanism 33, the check valve 191 is linked to the variable orifice 193. The damping force generating mechanism 33 has a first passage 232 connecting the lower chamber 20 and the upper chamber 19, and a first valve mechanism 42 provided in the first passage 232.

[0108] Next, the operation of the shock absorber 1, including the damping force generating mechanism 33, will be described.

[0109] {In the extension stroke, the piston frequency is low, and the piston speed is slower than a first predetermined value v1 in the low-frequency very low-speed region x1} In this low-frequency, very-low-speed region x1, the first valve mechanism 41 and the second valve mechanism 205 do not open. Then, the oil L from the upper chamber 19 flows into the sub-back pressure chamber 182 of the back pressure chamber 184 via the piston-side passage 43, the passage in the introduction orifice 142 of the disc 70, and the pilot chamber 95. As a result, the valve 192 of the frequency-sensitive mechanism 241 moves to the bottom side of the annular recess 125. In this low-frequency, very-low-speed region x1, because the piston frequency is low and the piston 18 has a large stroke, a large amount of oil L is introduced from the upper chamber 19 into the back pressure chamber 184 in the initial part of the stroke. Therefore, the valve 192 of the frequency-sensitive mechanism 241 moves and deforms to near its limit towards the bottom side of the annular recess 125, and thereafter it becomes difficult to deform (high spring region). On the other hand, in this low-frequency, very-low-speed region x1, the oil L from the upper chamber 19 flows into the lower chamber 20 via the fixed orifice 235. Therefore, in the low-frequency, very-low-speed range x1, a damping force with orifice characteristics (where the damping force is approximately proportional to the square of the piston speed) is generated. Consequently, in the low-frequency, very-low-speed range x1, the rate of increase in damping force with respect to increased piston speed is relatively high.

[0110] {During the extension stroke, the piston frequency is low, and the piston speed is greater than or equal to the first predetermined value v1 and slower than the second predetermined value v2, in a low-frequency, low-speed region x2} In this low-frequency, low-speed range x2, the oil L from the upper chamber 19 flows into the upper chamber 19 via the fixed orifice 235, similar to the low-frequency, very-low-speed range x1, and also causes the valve 192 of the frequency-sensitive mechanism 241 to move and deform significantly towards the bottom surface of the annular recess 125. Subsequently, the oil L from the upper chamber 19, via the piston-side passage 43, the passage in the introduction orifice 142 of the disc 70, and the pilot chamber 95, becomes less likely to be introduced into the back pressure chamber 184. In the low-frequency, low-speed range x2, the pressure in the back pressure chamber 184 is higher than in the low-frequency, very-low-speed range x1. Therefore, in the low-frequency, low-speed range x2, the oil L from the upper chamber 19 flows into the lower chamber 20 via the piston-side passage 43, the passage in the introduction orifice 142 of the disc 70, and the pilot chamber 95, opening the second damping valve 84 of the second valve mechanism 205. In other words, the oil L from the upper chamber 19 flows to the lower chamber 20 via the second passage 202. As a result, in the low-frequency, low-speed range x2, a damping force with valve characteristics (damping force is approximately proportional to piston speed) is generated. Therefore, in the low-frequency, low-speed range x2, the rate of increase in damping force with respect to increased piston speed is lower than in the low-frequency, very low-speed range x1. In this low-frequency, low-speed range x2, the valve 192 of the frequency-sensitive mechanism 241 moves and deforms to near its limit, so the pressure in the back pressure chamber 184 becomes high. Therefore, the first damping valve 72 of the first valve mechanism 41 is subjected to a large biasing force from the back pressure chamber 184, and thus its opening is restricted.

[0111] {During the extension stroke, the piston frequency is low, and the piston speed is in the low-frequency medium-high-speed range x3, where the piston speed is above a second predetermined value v2} In this low-frequency medium-high-speed range x3, the oil L from the upper chamber 19 flows into the upper chamber 19 via the fixed orifice 235, similar to the low-frequency very-low-speed range x1, and also opens the second damping valve 84 of the second valve mechanism 205, allowing the oil L to flow into the lower chamber 20 via the piston-side passage 43, the passage in the introduction orifice 142 of the disc 70, and the pilot chamber 95. In this low-frequency medium-high-speed range x3, since the oil L flows into the lower chamber 20 via the second passage 202, the pressure rise in the back pressure chamber 184 due to the oil L introduced into the back pressure chamber 184 from the pilot chamber 95 is suppressed. Conversely, the force applied to the first valve mechanism 41 from the piston-side passage 43 in the direction of valve opening increases, so the oil L from the upper chamber 19 passes through the piston-side passage 43, opens the first damping valve 72 of the first valve mechanism 41, and flows into the lower chamber 20. In other words, the oil L from the upper chamber 19 flows to the lower chamber 20 via the first passage 201. As a result, in the low-frequency medium-high-speed range x3, the rate of increase in damping force with respect to piston speed is lower than in the low-frequency low-speed range x2.

[0112] {In the extension stroke, the piston frequency is higher than the low frequency mentioned above, and the piston speed is slower than the third predetermined value v3 in the high-frequency very low-speed region x4} In this high-frequency, very low-speed range x4, the first valve mechanism 41 and the second valve mechanism 205 do not open. Then, the oil liquid L from the upper chamber 19 flows into the upper chamber 19 via the fixed orifice 235, as in the low-frequency, very low-speed range x1, and also flows into the sub-back pressure chamber 182 of the back pressure chamber 184 via the piston-side passage 43, the passage in the introduction orifice 142 of the disk 70, and the pilot chamber 95. As a result, the valve 192 of the frequency-sensitive mechanism 241 moves and deforms towards the bottom surface of the annular recess 125. In this high-frequency, very low-speed range x4, the piston frequency is high and the stroke of the piston 18 is small. Therefore, the amount of oil liquid L introduced from the upper chamber 19 into the back pressure chamber 184 is less than in the low-frequency, very low-speed range x1. Thus, the valve 192 of the frequency-sensitive mechanism 241 does not deform to near its limit and is easily deformed (low spring region). As a result, the oil liquid L introduced from the upper chamber 19 into the back pressure chamber 184 can be absorbed by the movement and deformation of the valve 192. Therefore, in the high-frequency very low-speed range x4, although the rate of increase in damping force with respect to the increase in piston speed is high, the damping force at the same piston speed is lower than in the low-frequency very low-speed range x1, resulting in a softer characteristic.

[0113] {During the extension stroke, the piston frequency is higher than the low frequency mentioned above, and the piston speed is in the high-frequency low-medium-high-speed range x5, which is greater than or equal to the third predetermined value v3} In the high-frequency low-medium-high-speed range x5, the oil L from the upper chamber 19 flows into the upper chamber 19 via the fixed orifice 235, similar to the high-frequency very-low-speed range x4, and also moves and deforms the valve 192 of the frequency-sensitive mechanism 241 towards the bottom of the annular recess 125. In the high-frequency low-medium-high-speed range x5, less oil L is introduced into the back pressure chamber 184, so the deformation of the valve 192 suppresses the pressure rise in the back pressure chamber 184. As a result, the biasing force from the back pressure chamber 184 to the first damping valve 72 of the first valve mechanism 41 becomes smaller, making it easier for the first damping valve 72 to open. Therefore, the oil L from the upper chamber 19 flows through the piston-side passage 43, opening the first damping valve 72 of the first valve mechanism 41 and flowing into the lower chamber 20. That is, the oil L from the upper chamber 19 flows into the lower chamber 20 via the first passage 201. As a result, in the high-frequency low-medium-high-speed range x5, the rate of increase in damping force with respect to piston speed is lower than in the high-frequency very-low-speed range x4. Also, in the high-frequency low-medium-high-speed range x5, the damping force at the same piston speed is lower than in the low-frequency low-speed range x2 and the low-frequency medium-high-speed range x3, resulting in a softer characteristic. In this high-frequency low-medium-high-speed range x5, the pressure rise in the back pressure chamber 184 is suppressed, so the second valve mechanism 205 remains in the closed state.

[0114] {In the compression stroke, the piston speed is in a very low-speed range y1 that is slower than the fourth predetermined value v4} In this very low speed range y1, the first valve mechanism 42 and the check valve 191 do not open. Then, the oil L from the lower chamber 20 flows to the upper chamber through the fixed orifice 235. Therefore, in the very low speed range y1, a damping force with orifice characteristics (damping force is approximately proportional to the square of the piston speed) is generated. For this reason, in the very low speed range y1, the rate of increase in damping force with respect to the increase in piston speed is relatively high.

[0115] {During the compression stroke, the piston speed is in the low-speed range y2, where the piston speed is greater than or equal to the fourth predetermined value v4 and slower than the fifth predetermined value v5} In this low-speed range y2, the oil L from the lower chamber 20 flows to the upper chamber 19 via the fixed orifice 235, similar to the very low-speed range y1. In addition, in the low-speed range y2, the oil L from the lower chamber 20 is introduced into the variable chamber 183 from the lower chamber communication passage 211, opens the check valve 191, is introduced into the pilot chamber 95, and flows to the upper chamber 19 via the introduction orifice 142 of the disc 70 and the piston-side passage 43. In the low-speed range y2, the rate of increase in damping force with respect to the increase in piston speed is lower than in the very low-speed range y1. At this time, the valve 192 of the opened check valve 191 narrows the passage in the variable orifice 193, suppressing the pressure rise in the sub-back pressure chamber 182, and further, the communication orifice 166 suppresses the pressure rise in the main back pressure chamber 181.

[0116] {In the compression stroke, the piston speed is in the medium to high speed range y3, where the piston speed is equal to or greater than the fifth predetermined value v5} In the medium-to-high speed range y3, similar to the low-speed range y2, the oil L from the lower chamber 20 flows to the upper chamber 19 via the fixed orifice 235, and also flows to the upper chamber 19 via the pilot chamber 95, the introduction orifice 142, and the piston-side passage 43, opening the check valve 191 from the lower chamber communication passage 211. In the medium-to-high speed range y3, in addition to these, the oil L from the lower chamber 20 also flows through the piston-side passage 44, opening the first damping valve 231 of the first valve mechanism 42, and flows to the upper chamber 19. As a result, in the medium-to-high speed range y3, the rate of increase in damping force with respect to piston speed is lower than in the low-speed range y2. At this time as well, the valve 192 of the opened check valve 191 narrows the passage in the variable orifice 193, suppressing the pressure rise in the sub-back pressure chamber 182, and furthermore, the communication orifice 166 suppresses the pressure rise in the main back pressure chamber 181.

[0117] Here, the diameter of the back pressure chamber 184 is larger than the diameter of the valve seat portion 53 of the piston 18. Therefore, during the compression stroke, the extension-side first damping valve 72 is subjected to the pressure of the lower chamber 20.

[0118] When the pressure in the lower chamber 20 rises during the compression stroke and reaches a predetermined pressure, the valve 192 of the check valve 191 provided in the pilot case 81 opens, introducing pressure into the back pressure chamber 184. As a result, a closing force due to the back pressure acts on the first damping valve 72, which exceeds the opening force due to the pressure in the lower chamber 20 acting on the outer circumference of the first damping valve 72, thereby preventing the first damping valve 72 from opening during the compression stroke.

[0119] Furthermore, during the compression stroke, the shock absorber 1 also exhibits damping force characteristics that combine with those of the damping valve mechanism 257.

[0120] Patent Document 1, mentioned above, discloses a shock absorber having a damping force generation mechanism in which the damping force is variable in response to frequency. In a shock absorber, it is required that the damping force generation mechanism operate smoothly. For example, the shock absorber described in Patent Document 1 is provided with a free valve that functions as a check valve during the compression stroke and as a back pressure introduction valve during the extension stroke. In this case, if the back pressure chamber becomes high pressure when the check valve is opened during the compression stroke, when the check valve closes during the stroke reversal from the compression stroke to the extension stroke, the high back pressure in the back pressure chamber may hinder the smooth opening of the damping force generation mechanism on the extension side, potentially increasing the damping force. As a result, it becomes difficult to generate a soft damping force when the stroke reversal from the compression stroke to the extension stroke is required.

[0121] The shock absorber 1 of the first embodiment has a first passage 201 through which the working fluid, oil liquid L, flows out from one upper chamber 19 in the cylinder 2 as the piston 18 moves, and a second passage 202 provided in parallel with the first passage 201. The shock absorber 1 also has a first valve mechanism 41 provided in the first passage 201 that acts when the upper chamber 19 is in the extension stroke of the upstream pressure and can adjust the damping force by the pressure in the main back pressure chamber 181, and a frequency-sensitive mechanism 241 provided in the second passage 202 that acts when the upper chamber 19 is in the upstream pressure and changes the volume by the movement of a valve 192. The shock absorber 1 also has a check valve 191 provided in the second passage 202 that acts when the lower chamber 20 is in the upstream pressure and allows the oil liquid L to flow. Downstream of the check valve 191, the shock absorber 1 is provided with a variable orifice 193 that acts when the lower chamber 20 is in the compression stroke of the upstream pressure and controls the flow of oil liquid L to the main back pressure chamber 181. As a result, even if the check valve 191 is opened during the compression stroke, the flow of oil L into the main back pressure chamber 181 can be suppressed by the variable orifice 193, thereby preventing the main back pressure chamber 181 from becoming high pressure. Therefore, it is possible to prevent the back pressure in the main back pressure chamber 181 from hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the compression stroke to the extension stroke. Consequently, it becomes possible to operate the damping force generating mechanism 33, including the first valve mechanism 41, smoothly. As a result, it becomes possible to generate a good soft damping force when generating a soft damping force when the stroke is reversed from the compression stroke to the extension stroke.

[0122] Furthermore, since the valve 192 of the shock absorber 1 also functions as the check valve 191, the number of parts in the damping force generating mechanism 33 can be reduced, allowing for miniaturization. Reducing the number of parts in the damping force generating mechanism 33 makes it possible to reduce the cost and weight of the shock absorber 1.

[0123] Furthermore, the shock absorber 1 has a sub-back pressure chamber 182 between the variable orifice 193 and the main back pressure chamber 181. Therefore, even if the check valve 191 is opened during the compression stroke, the oil liquid L flows from the variable orifice 193 to the sub-back pressure chamber 182, and from the sub-back pressure chamber 182 to the main back pressure chamber 181. Thus, the flow of oil liquid L to the main back pressure chamber 181 can be further suppressed, and the main back pressure chamber 181 can be further suppressed from becoming high pressure. As a result, the back pressure in the main back pressure chamber 181 hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the compression stroke to the extension stroke can be further suppressed. Therefore, the damping force generation mechanism 33, including the first valve mechanism 41, can be operated more smoothly.

[0124] Furthermore, in the shock absorber 1, the sub-back pressure chamber 182 is connected to the main back pressure chamber 181 via a communicating orifice 166. Therefore, even if the check valve 191 is opened during the compression stroke, the flow of oil L into the sub-back pressure chamber 182 can be suppressed by the variable orifice 193, and the flow of oil L from the sub-back pressure chamber 182 to the main back pressure chamber 181 can be suppressed by the communicating orifice 166. Thus, the main back pressure chamber 181 can be further suppressed from becoming high pressure. As a result, the back pressure in the main back pressure chamber 181 hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the compression stroke to the extension stroke can be further suppressed. Therefore, the damping force generation mechanism 33, including the first valve mechanism 41, can be operated more smoothly.

[0125] The damping force generating mechanism 33 of the first embodiment includes a pilot case 81, a valve 192, and a regulating disc 78. The pilot case 81 is bottomed cylindrical and forms a back pressure chamber 184 that generates a biasing force in the valve closing direction for the first damping valve 72 located on the opening 103 side. The valve 192 is provided at the bottom 101 of the pilot case 81 and defines a variable chamber 183 on the opposite side of the back pressure chamber 184, blocking the flow of oil L from the back pressure chamber 184 to the variable chamber 183. The regulating disc 78 abuts against the outer circumference of the valve 192 and restricts the opening of the valve 192. The valve 192 has a variable orifice 193 that restricts the inflow of oil L from the variable chamber 183 to the back pressure chamber 184. As a result, even when valve 192 is opened, the variable orifice 193 can restrict the inflow of oil L from the variable chamber 183 to the back pressure chamber 184, thereby suppressing the back pressure chamber 184 from becoming high pressure. Therefore, it is possible to prevent the back pressure in the back pressure chamber 184 from hindering the smooth opening of the first valve mechanism 41 during stroke reversal. Consequently, the damping force generating mechanism 33 can operate smoothly.

[0126] The shock absorber 1 and damping force generating mechanism 33 of the first embodiment can be modified as shown in the following modified examples 1 and 2.

[0127] <Example 1> In the shock absorber 1 and damping force generating mechanism 33 of the first embodiment, the regulating disc 78 is formed by welding disc 162 to disc 161 to form a single unit. However, disc 162 may be integrated with the outer circumference of disc 91 of the valve 192 on the opposite side of disc 92 by welding, rather than welding disc 162 to disc 161. In this case, disc 161 (regulating member) contacts disc 162 which is integrated with disc 91, pressing the valve 192 including disc 162 against the outer seat portion 114 of the pilot case 81. That is, in this case, disc 161 contacts the outer circumference of the valve 192 including disc 162, thereby restricting the opening of the valve 192.

[0128] <Modification 2> The disc 162 is positioned radially within the cylindrical portion 102 of the pilot case 81 without being welded to either the disc 161 or the disc 91. In this case, the disc 162 is sandwiched axially between the disc 161 and the disc 91, and the disc 162 (regulating member) comes into contact with the disc 91, pressing the valve 192 against the outer seat portion 114 of the pilot case 81. In other words, in this case, the outer circumference of the valve 192 comes into contact with the disc 162, regulating the opening of the valve 192.

[0129] [Second Embodiment] Next, the second embodiment will be described, primarily based on Figure 7, focusing on the differences from the first embodiment. Parts common to both the first and second embodiments will be represented by the same designations and reference numerals.

[0130] As shown in Figure 7, the shock absorber 1A of the second embodiment has a damping force generating mechanism 33A which is partially different from the damping force generating mechanism 33, in place of the damping force generating mechanism 33. The damping force generating mechanism 33A has a regulating disc 78A which is partially different from the regulating disc 78, in place of the regulating disc 78. The regulating disc 78A has a disc 161A which is partially different from the disc 161, in place of the disc 161.

[0131] The disk 161A has slits 171A formed inside the through-hole 165 in the radial direction of the disk 161A. The slits 171A penetrate the disk 161A in the axial direction of the disk 161A. The slits 171A are in a straight line extending radially across the disk 161A. Multiple slits 171A are provided on the disk 161A at equal intervals in the circumferential direction of the disk 161. The slits 171A open into the sub-back pressure chamber 182.

[0132] The damping force generating mechanism 33A replaces valve 192 with valve 192A (movable member), which is partially different from valve 192. Valve 192A replaces disc 91 with disc 91A, which is partially different from disc 91.

[0133] The notch 171 that was formed on disc 91 is not formed on disc 91A. The outer diameter of disc 91A is constant around its entire circumference, and the inner diameter is also constant around its entire circumference. Disc 91A is a common part with the same shape as disc 92.

[0134] The damping force generating mechanism 33A replaces the check valve 191 with a check valve 191A, which is slightly different from the check valve 191. The check valve 191A differs from the check valve 191 in that it has a valve 192A instead of a valve 192. In the check valve 191A, the valve 192A operates in the same way as the valve 192. Therefore, the check valve 191A operates in the same way as the check valve 191.

[0135] The damping force generating mechanism 33A replaces the frequency-sensitive mechanism 241 with a frequency-sensitive mechanism 241A, which is partially different from the frequency-sensitive mechanism 241. The frequency-sensitive mechanism 241A differs from the frequency-sensitive mechanism 241 in that it has a valve 192A instead of valve 192. In the frequency-sensitive mechanism 241A, valve 192A operates in the same way as valve 192. Therefore, the frequency-sensitive mechanism 241A operates in the same way as the frequency-sensitive mechanism 241.

[0136] The damping force generating mechanism 33A replaces the variable orifice 193 with a variable orifice 193A (first throttling mechanism, first throttling section) which is partially different from the variable orifice 193. When the check valve 191A is opened, the inner circumferential portion of the valve 192A approaches the disc 161A of the regulating disc 78A, narrowing the flow path between the disc 161A and the variable orifice 193A. The inner circumferential portion of the valve 192A and the disc 161A of the regulating disc 78A constitute the variable orifice 193A. The flow path cross-sectional area of ​​the variable orifice 193A is smaller than the flow path cross-sectional area of ​​the communication orifice 166. The variable orifice 193A is provided between the pilot chamber 95 and the sub-back pressure chamber 182, and changes the flow path between the pilot chamber 95 and the sub-back pressure chamber 182 according to the amount of deformation of the valve 192A. The variable orifice 193A includes a slit 171A in the disk 161A. The passage within the slit 171A of disk 161A makes the flow path cross-sectional area within the variable orifice 193A a non-zero minimum value when the disk 91A of valve 192A contacts the disk 161A of regulating disk 78A. In other words, the slit 171A of disk 161A performs the same function as the notch 171 of disk 91. In this way, valve 192A constitutes a variable orifice 193A that restricts the inflow of oil liquid L from the variable chamber 183 to the sub-back pressure chamber 182. Valve 192A also functions as a check valve 191A. The sub-back pressure chamber 182 is provided between the variable orifice 193A and the main back pressure chamber 181.

[0137] The damping force generating mechanism 33A has a second passage 202A in place of the second passage 202, which is partially different from the second passage 202. The second passage 202A differs from the second passage 202 in that it has a variable orifice 193A in place of the variable orifice 193.

[0138] During the compression stroke, when the valve 192A of the check valve 191A separates from the valve seat portion 113, the valve 192A narrows the flow path cross-sectional area of ​​the passage in the variable orifice 193A between the valve 192A and the disc 161A of the regulating disc 78A. This suppresses the flow of oil liquid L from the lower chamber 20 to the sub-back pressure chamber 182 via the lower chamber connecting passage 211, the variable chamber 183, and the open check valve 191A. As a result, the pressure rise in the sub-back pressure chamber 182 is suppressed. In this way, when the lower chamber 20 is under upstream pressure, the variable orifice 193A located downstream of the check valve 191A acts to suppress and control the flow of oil liquid L, which is the working fluid, to the sub-back pressure chamber 182 and the main back pressure chamber 181.

[0139] The configuration of the damping force generating mechanism 33A described above is the same as that of the damping force generating mechanism 33 in the first embodiment, as shown in the hydraulic circuit diagram. That is, in Figure 6, the second passage 202 becomes the second passage 202A, the check valve 191 becomes the check valve 191A, the variable orifice 193 becomes the variable orifice 193A, and the frequency-sensitive mechanism 241 becomes the frequency-sensitive mechanism 241A.

[0140] The shock absorber 1A and damping force generating mechanism 33A of the second embodiment also have a variable orifice 193A that acts similarly to the variable orifice 193, and therefore achieve the same effects as the shock absorber 1 and damping force generating mechanism 33 of the first embodiment.

[0141] The shock absorber 1A and damping force generating mechanism 33A of the second embodiment can be modified as shown in Modification 1 and Modification 2 of the first embodiment. That is, instead of welding the disc 162 to the disc 161A, it may be integrated by welding to the outer circumference of the disc 91A of the valve 192A on the side opposite to the disc 92. Alternatively, the disc 162 may be positioned radially by the cylindrical portion 102 of the pilot case 81 and sandwiched axially between the disc 161 and the disc 91A, without welding it to either the disc 161 or the disc 91A.

[0142] [Third Embodiment] Next, the third embodiment will be described, primarily based on Figures 8 to 10, focusing on the differences from the first embodiment. Parts common to both the first and third embodiments will be represented by the same designations and reference numerals.

[0143] As shown in Figure 8, the shock absorber 1B of the third embodiment has a damping force generating mechanism 33B which is partially different from the damping force generating mechanism 33, in place of the damping force generating mechanism 33. The damping force generating mechanism 33B has a regulating disk 78B which is partially different from the regulating disk 78, in place of the regulating disk 78. The regulating disk 78B has a disk 161B which is partially different from the disk 161, in place of the disk 161.

[0144] Disk 161B has a through hole 165B that is partially different from the through hole 165, replacing the through hole 165. The through hole 165B penetrates the disk 161B in the axial direction of the disk 161B. In the radial direction of the disk 161B, the through hole 165B extends inward more than the through hole 165. The through hole 165B opens into the sub-back pressure chamber 182. Multiple through holes 165B are provided on the disk 161B at equal intervals in the circumferential direction of the disk 161B. The through holes 165B, together with the notch 155 of the disk 77, constitute a communication orifice 166 similar to that of the first embodiment.

[0145] The damping force generating mechanism 33B replaces valve 192 with valve 192B (movable member), which is partially different from valve 192. Valve 192B replaces disc 91 with disc 91B, which is partially different from disc 91.

[0146] Disk 91B does not have the notch 171 formed on disk 91. Disk 91B has a constant outer diameter and a constant inner diameter throughout its entire circumference. Disk 91B is a common part with the same shape as disk 92.

[0147] The damping force generating mechanism 33B replaces the check valve 191 with a check valve 191B, which is slightly different from the check valve 191. The check valve 191B differs from the check valve 191 in that it has a valve 192B instead of a valve 192. In the check valve 191B, the valve 192B operates in the same way as the valve 192. Therefore, the check valve 191B operates in the same way as the check valve 191.

[0148] The damping force generating mechanism 33B replaces the frequency-sensitive mechanism 241 with a frequency-sensitive mechanism 241B, which is partially different from the frequency-sensitive mechanism 241. The frequency-sensitive mechanism 241B differs from the frequency-sensitive mechanism 241 in that it has a valve 192B instead of a valve 192. In the frequency-sensitive mechanism 241B, the valve 192B operates in the same way as the valve 192. Therefore, the frequency-sensitive mechanism 241B operates in the same way as the frequency-sensitive mechanism 241.

[0149] The damping force generating mechanism 33B is not provided with a variable orifice 193. The passage in the through hole 165B of the disc 161B connects the variable chamber 183 and pilot chamber 95 with the sub-back pressure chamber 182, even when the disc 91B of the valve 192B comes into contact with the disc 161B of the regulating disc 78B.

[0150] The damping force generating mechanism 33B has a pilot case 81B which is partially different from the pilot case 81, replacing the pilot case 81. The pilot case 81B has a bottom 101B which is partially different from the bottom 101, replacing the bottom 101. The bottom 101B has a bottom body part 111B which is partially different from the bottom body part 111, replacing the bottom body part 111. As shown in Figure 9, the bottom body part 111B is provided with only one passage hole 121.

[0151] The bottom portion 101B has an outer sheet portion 116B that is partially different from the outer sheet portion 116. The outer sheet portion 116B has a connecting sheet portion 311B that connects the sheet component 133, which has a passage hole 121 positioned between it and the sheet component 133 in the circumferential direction of the pilot case 81B. The connecting sheet portion 311B is positioned outside the passage hole 121 in the radial direction of the pilot case 81B. As shown in Figure 8, in the axial direction of the pilot case 81B, the tip surface of the connecting sheet portion 311B opposite to the bottom body portion 111B is aligned with the tip surface of the inner sheet portion 115 opposite to the bottom body portion 111B and the tip surface of the sheet component 133 opposite to the bottom body portion 111B.

[0152] The connecting sheet portion 311B has a notch 312B that penetrates the connecting sheet portion 311B radially through the pilot case 81B. The notch 312B is recessed toward the bottom body portion 111B from the front end surface of the connecting sheet portion 311B opposite to the bottom body portion 111B. The notch 312B is formed in the pilot case 81B by coining. The notch 312B, together with the disk 83 that abuts the outer sheet portion 116B, constitutes an orifice 313B.

[0153] As shown in Figure 9, the passage recess 315B is formed by two sheet components 133 located on both sides of the passage hole 121 in the circumferential direction of the pilot case 81B, the portion of the inner sheet component 115 between these sheet components 133, and the connecting sheet component 311B. As shown in Figure 8, the passage recess 315B is recessed along the axial direction of the pilot case 81 from the protruding end surface of the inner sheet component 115, the protruding end surface of the sheet component 133, and the end surface of the connecting sheet component 311B. The bottom surface of the passage recess 315B is formed by the bottom body component 111. The orifice 313B opens to the inside of the passage recess 315B and to the lower chamber 20.

[0154] The damping force generating mechanism 33B replaces the lower chamber connecting passage 211 with a lower chamber connecting passage 211B, which is partially different from the lower chamber connecting passage 211. The lower chamber connecting passage 211B consists of a passage within the passage recess 315B and a passage within the passage hole 121. The lower chamber connecting passage 211B communicates with the lower chamber 20 via an orifice 313B.

[0155] The damping force generating mechanism 33B has a second passage 202B in place of the second passage 202, which is partially different from the second passage 202. The second passage 202B differs from the second passage 202 in that it has a lower chamber connecting passage 211B in place of the lower chamber connecting passage 211, it has an orifice 313B, and it does not have a variable orifice 193.

[0156] During the compression stroke, the orifice 313B of the pilot case 81B acts to suppress the flow of oil L from the lower chamber 20 to the lower chamber connecting passage 211B and the variable chamber 183. This suppresses the flow of oil L from the lower chamber 20 to the sub-back pressure chamber 182 via the orifice 313B, the lower chamber connecting passage 211B and the open check valve 191B. As a result, the pressure rise in the sub-back pressure chamber 182 is suppressed. In this way, when the lower chamber 20 is under upstream pressure, the orifice 313B located upstream of the check valve 191B acts to suppress and control the flow of oil L, which is the working fluid, to the sub-back pressure chamber 182 and the main back pressure chamber 181.

[0157] The configuration of the damping force generating mechanism 33B described above is shown in the hydraulic circuit diagram in Figure 10. Specifically, the check valve 191 becomes the check valve 191B, the frequency-sensitive mechanism 241 becomes the frequency-sensitive mechanism 241B, and an orifice 313B is provided between the lower chamber connecting passage 211B and the lower chamber 20. In addition, the damping force generating mechanism 33B has the second passage 202 become the second passage 202B, and the variable orifice 193 is not provided in this second passage 202B.

[0158] In the third embodiment, the buffer 1B is provided with an orifice 313B upstream of the check valve 191B, which acts on the lower chamber 20 during the compression stroke of the upstream pressure to control the flow of oil liquid L into the main back pressure chamber 181. As a result, even if the check valve 191 is opened during the compression stroke, the flow of oil liquid L into the main back pressure chamber 181 can be suppressed by the orifice 313B, thereby preventing the main back pressure chamber 181 from becoming high pressure. Therefore, it is possible to prevent the back pressure in the main back pressure chamber 181 from hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the compression stroke to the extension stroke. Consequently, it becomes possible to smoothly operate the damping force generating mechanism 33B including the first valve mechanism 41. As a result, it becomes possible to generate a soft damping force well in situations where a soft damping force is generated when the stroke is reversed from the compression stroke to the extension stroke.

[0159] Furthermore, the shock absorber 1B has a sub-back pressure chamber 182 between the orifice 313B and the main back pressure chamber 181. Therefore, even if the check valve 191 is opened during the compression stroke, the oil liquid L flows from the orifice 313B to the sub-back pressure chamber 182, and from the sub-back pressure chamber 182 to the main back pressure chamber 181. Thus, the flow of oil liquid L to the main back pressure chamber 181 can be further suppressed, and the main back pressure chamber 181 can be further suppressed from becoming high pressure. As a result, the back pressure in the main back pressure chamber 181 hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the compression stroke to the extension stroke can be further suppressed. Therefore, the damping force generating mechanism 33B, including the first valve mechanism 41, can be operated more smoothly.

[0160] The shock absorber 1B and damping force generating mechanism 33B of the third embodiment can be modified as shown in Modifications 1 and 2 of the first embodiment. That is, instead of welding the disc 162 to the disc 161B, it may be integrated by welding to the outer circumference of the disc 91B of the valve 192B on the side opposite to the disc 92. Alternatively, the disc 162 may be positioned radially by the cylindrical portion 102 of the pilot case 81 and sandwiched axially between the disc 161 and the disc 91B, without welding it to either the disc 161 or the disc 91B.

[0161] [Other application examples of the 1st to 3rd embodiments] The configurations of the first to third embodiments can all be applied to a built-in control valve type damping force generation mechanism.

[0162] For example, Figures 11 and 12 show a shock absorber 1C having a built-in control valve type damping force generation mechanism 33C, illustrating an example in which the main components of the damping force generation mechanism 33B of the third embodiment are applied to the extension side of the damping force generation mechanism 33C. Here again, parts common to the third embodiment are represented by the same designation and reference numerals.

[0163] As shown in Figure 11, the damping force generating mechanism 33C separates the inner cylinder 3 of the cylinder 2 into an upper chamber 19 and a lower chamber 20 by a piston 18C. The damping force generating mechanism 33C has a case 401C, a solenoid 402C covered by the case 401C, and a piston bolt portion 403C which is a shaft member. The case 401C of the damping force generating mechanism 33C is connected to a connecting rod 404C. This connecting rod 404C extends out of the cylinder 2 through a rod guide 22 (see Figure 1) and a sealing member 23 (see Figure 1).

[0164] A damping force generating mechanism 411C for extension is provided on the lower chamber 20 side of the piston 18C, and a damping force generating mechanism 412C for compression is provided on the upper chamber 19 side of the piston 18C.

[0165] The extension damping force generation mechanism 411C will be explained with reference to Figure 12. The oil liquid L that has passed from the upper chamber 19 through the extension side piston passage 43C passes through the extension side introduction orifice 142 provided in the disc 70, passes through the extension side introduction port 416C provided in the piston bolt 415C, and enters the extension side pilot chamber 95C.

[0166] The extension-side pilot chamber 95C is connected to the back pressure chamber 184 for the extension-side first damping valve 72 via a pilot communication passage 418C provided on the piston bolt 415C and a passage in a passage groove 124 provided on the pilot case 81B.

[0167] The pilot valve 421C, installed within the piston bolt 415C, receives a closing force from the thrust of the solenoid 402C. The valve opens when the opening force, resulting from the biasing force of the spring 422C and the pressure in the pilot chamber 95C, exceeds the thrust of the solenoid 402C. When the pilot valve 421C opens, the oil L in the pilot chamber 95C passes through the compression-side introduction port 424C, opens the disc valve 426C which is equipped with a compression-side introduction orifice 425C, passes through the compression-side piston-side passage 44C, and flows into the lower chamber 20.

[0168] The oil L that has passed from the upper chamber 19 through the extension-side piston passage 43C passes through the extension-side introduction orifice 142 provided in the disc 70, passes through the extension-side introduction port 416C provided in the piston bolt 415C, and enters the extension-side pilot chamber 95C. Subsequently, the oil L that has passed through the passage in the passage groove 30C provided in the piston bolt 415C is introduced into the sub-back pressure chamber 182 of the back pressure chamber 184 via the passage in the passage groove 124 provided in the pilot case 81B, passes through the communication orifice 166 provided in the regulating disc 78B and disc 77, and enters the main back pressure chamber 181 of the back pressure chamber 184.

[0169] Valve 192B, located in the sub-back pressure chamber 182, separates the variable chamber 183, into which oil liquid L is introduced from the lower chamber 20 via the orifice 313B and lower chamber connecting passage 211B located in the pilot case 81B, from the sub-back pressure chamber 182. Valve 192B also constitutes a check valve 191B that allows only the flow of oil liquid L from the lower chamber 20 to the back pressure chamber 184 via the orifice 313B and lower chamber connecting passage 211B. During the extension stroke, the check valve 191B is normally closed to maintain the pilot pressure in the back pressure chamber 184. When the axial movement of the piston 18C is high frequency, the deflection of valve 192B is small, resulting in a low internal pressure in the back pressure chamber 184. Conversely, when the axial movement of the piston 18C is low frequency, the deflection of valve 192B is large, resulting in a high internal pressure in the back pressure chamber 184. Therefore, the opening pressure of the first damping valve 72 can be changed according to the frequency. This frequency can be adjusted by the introduction orifice 142 provided in the disk 70. Furthermore, the opening pressure of the first damping valve 72 can be adjusted by the disk stiffness of the first damping valve 72 at high frequencies, and by the disk stiffness of the second damping valve 84 at low frequencies. Volume compensation for the moving volume of valve 192B is performed by the lower chamber connecting passage 211B and orifice 313B provided in the pilot case 81B.

[0170] When the oil liquid L in the back pressure chamber 184 reaches a predetermined pressure, it passes through the passage in the passage groove 30C, opens the second damping valve 84, and flows into the lower chamber 20. When the first damping valve 72 opens during the extension stroke, the second damping valve 84 is open in this way, so the back pressure chamber 184 is in communication with the lower chamber 20. Therefore, it is possible to compensate for the volume of the oil liquid L equivalent to the movement volume of the first damping valve 72.

[0171] Here, the diameter of the back pressure chamber 184 is larger than the diameter of the valve seat portion 53 of the piston 18C. Therefore, during the compression stroke, the extension-side first damping valve 72 is subjected to the pressure of the lower chamber 20.

[0172] When the pressure in the lower chamber 20 rises during the compression stroke and reaches a predetermined pressure, valve 192B of the check valve 191B provided in the pilot case 81B opens, introducing pressure into the back pressure chamber 184 and applying a closing force due to the back pressure to the first damping valve 72. This closing force exceeds the opening force due to the pressure in the lower chamber 20 acting on the outer circumference of the first damping valve 72, thereby preventing the first damping valve 72 from opening during the compression stroke.

[0173] The damping force generation mechanism 412C on the compression side will now be explained. The oil liquid L that has passed from the lower chamber 20 through the compression-side piston passage 44C passes through the compression-side introduction orifice 425C provided in the disc valve 426C and enters the passage within the compression-side passage groove 431C.

[0174] The passage within the compression-side passage groove 431C is connected to the back pressure chamber 442C for the compression-side first damping valve 441C via the orifice 455C of the check valve 451C provided in the pilot case 432C.

[0175] The pilot valve 421C, installed within the piston bolt 415C, receives a closing force from the thrust of the solenoid 402C. It opens when the opening force due to the pressure between the spring 422C and the pilot chamber 95C exceeds the thrust of the solenoid 402C. When the pilot valve 421C opens, the oil liquid L that has entered the passage in the passage groove 431C flows from the compression side introduction port 424C, through the extension side pilot chamber 95C, opens the disk 70 equipped with the extension side introduction orifice 142, and flows through the extension side piston side passage 43C to the upper chamber 19.

[0176] Inside the pilot case 432C, there is a check valve 451C that allows only the flow of oil L from the upper chamber 19 to the back pressure chamber 442C, and an upper chamber connecting passage 452C. The check valve 451C is provided with an orifice 455C on its inner circumference. During the compression stroke, the check valve 451C is always closed to maintain the pilot pressure in the back pressure chamber 442C.

[0177] When the first damping valve 441C opens during the compression stroke, the back pressure chamber 442C is in communication with the upper chamber 19 via the orifice 455C and the passage in the passage groove 431C, making it possible to compensate for the volume of the oil liquid L corresponding to the movement volume of the first damping valve 441C.

[0178] At the bottom of the pilot case 432C, where the first damping valve 441C on the compression side is installed, there is a second damping valve 461C for relieving the pressure in the back pressure chamber 442C, which has reached a predetermined pressure, to the upper chamber 19, as well as an inner circumferential groove 462C and a relief passage 463C.

[0179] The seat of the second damping valve 461C is an irregularly shaped seat that separates the relief passage 463C and the upper chamber passage 452C. The amount of back pressure introduced can be adjusted by a notch 465C provided in the seat.

[0180] Here, since the diameter of the back pressure chamber 442C of the first damping valve 441C is larger than the diameter of the valve seat portion 57 of the piston 18C, during the extension stroke, the compression-side first damping valve 441C is subjected to the pressure of the upper chamber 19.

[0181] When the pressure in the upper chamber 19 rises during the extension stroke and reaches a predetermined pressure, the check valve 451C opens to introduce pressure into the back pressure chamber 442C, causing a closing force due to the back pressure to act on the first damping valve 441C. This closing force exceeds the opening force due to the pressure in the upper chamber 19 acting on the outer circumference of the first damping valve 441C, thereby preventing the first damping valve 441C from opening during the extension stroke. [Industrial applicability]

[0182] According to the above embodiment of the present invention, a shock absorber is provided that enables the damping force generation mechanism to operate smoothly. Therefore, it has great industrial applicability. [Explanation of symbols]

[0183] 1, 1A, 1B, 1C... Shock absorber, 2... Cylinder, 18... Piston, 19... Upper chamber (first cylinder chamber), 20... Lower chamber (second cylinder chamber), 41... First valve mechanism (valve mechanism), 72... First damping valve (damping force generating member), 78, 78A, 78B... Regulating disc (regulating member), 81... Pilot case (biasing force generating member), 101... Bottom, 166... ​​Communicating orifice (second throttling mechanism), 181 ...Main back pressure chamber, 182...Sub back pressure chamber, 183...Variable chamber, 184...Back pressure chamber, 191, 191A, 191B...Check valve, 192, 192A, 192B...Valve (movable member), 193, 193A...Variable orifice (first throttling mechanism, first throttling section), 201...First passage, 202...Second passage, 241, 241, 241B...Frequency-sensitive mechanism, 313B...Orifice (first throttling mechanism, first throttling section).

Claims

[Claim 1] A cylinder in which the working fluid is sealed, A piston is slidably fitted inside the cylinder, dividing the inside of the cylinder into a first cylinder chamber and a second cylinder chamber. A first passage through which working fluid flows out from one chamber within the cylinder due to the movement of the piston, A second passage is provided in parallel with the first passage, In both cases, the first cylinder chamber acts when there is an upstream pressure. A valve mechanism provided in the first passage, capable of adjusting the damping force by the pressure of the main back pressure chamber, A frequency-sensitive mechanism provided in the second passage that changes volume by the movement of a movable member, In both cases, the second cylinder chamber acts when there is an upstream pressure. A check valve provided in the second passage, When the check valve opens, it operates to narrow a portion of the flow path of the second passage, thereby controlling the flow of the working fluid to the main back pressure chamber, and a variable orifice A shock absorber having a shock absorber.

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