Shock absorber and damping force generating mechanism

Abstract

The shock absorber is provided with: a cylinder in which a working fluid is sealed; a piston which is slidably fitted in the cylinder and divides the inside of the cylinder into a first cylinder chamber and a second cylinder chamber; a first passage through which a working fluid flows out from one chamber in the cylinder by the movement of the piston; a second passage provided in parallel with the first passage; a valve mechanism provided in the first passage and capable of adjusting a damping force using the pressure of the main back pressure chamber; a frequency sensing mechanism, which is provided in the second passage, and which changes the volume by the movement of a movable member; a one-way valve provided in the second passage; a first throttle mechanism which is provided downstream or upstream of the check valve and controls the flow of the working fluid to the main back pressure chamber; the valve mechanism and the frequency sensing mechanism play a role when the first cylinder chamber is under the upstream pressure, and the one-way valve and the first throttling mechanism play a role when the second cylinder chamber is under the upstream pressure.

Description

Technical Field

[0001] The invention relates to a buffer and a damping force generating mechanism.

[0002] This application claims priority based on Japanese patent application No. 2022-189298, filed on November 28, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Some shock absorbers have a damping force generating mechanism in which the damping force is variable in response to the frequency (for example, refer to Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-55850 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] In the shock absorber, it is required that the damping force generating mechanism operate smoothly.

[0009] Therefore, the present invention provides a shock absorber and a damping force generating mechanism capable of causing the damping force generating mechanism to operate smoothly.

[0010] Technical solutions for solving technical problems

[0011] A shock absorber according to a first aspect of the present invention comprises: a cylinder in which a working fluid is sealed;

[0012] A piston is slidably embedded in the cylinder to divide the cylinder into a first cylinder chamber and a second cylinder chamber; a first passage allows working fluid to flow out from a chamber in the cylinder through the movement of the piston; a second passage is arranged in parallel with the first passage; a valve mechanism is arranged in the first passage and can adjust the damping force using the pressure in the main back pressure chamber; a frequency sensing mechanism is arranged in the second passage and changes the volume through the movement of a movable part; a one-way valve is arranged in the second passage; a first throttling mechanism is arranged downstream or upstream of the one-way valve to control the flow of working fluid to the main back pressure chamber; the valve mechanism and the frequency sensing mechanism both function when the first cylinder chamber is at an upstream pressure, and the one-way valve and the first throttling mechanism both function when the second cylinder chamber is at an upstream pressure.

[0013] The damping force generating mechanism of the second scheme of the present invention comprises: a force generating component, which is a bottomed cylindrical shape, forming a back pressure chamber for generating a force in the valve closing direction in the damping force generating component arranged on the opening side; a valve, which is arranged at the bottom of the force generating component, divides the variable chamber on the side opposite to the back pressure chamber, and cuts off the flow of working fluid from the back pressure chamber to the variable chamber; a limiting component, which abuts against the outer peripheral side of the valve to limit the opening of the valve; and the valve has a first throttling portion for limiting the inflow of working fluid from the variable chamber to the back pressure chamber.

[0014] Effects of the Invention

[0015] According to the above aspect, the damping force generating mechanism can be operated smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional view showing the shock absorber according to the first embodiment of the present invention.

[0017] Figure 2 It is a cross-sectional view showing a damping force generating mechanism of the shock absorber according to the first embodiment of the present invention.

[0018] Figure 3 It is a cross-sectional view showing the structure of the main part of the shock absorber according to the first embodiment of the present invention.

[0019] Figure 4 It is a cross-sectional view showing the structure of the main part of the shock absorber according to the first embodiment of the present invention.

[0020] Figure 5 It is a bottom view showing the pilot housing of the shock absorber according to the first embodiment of the present invention.

[0021] Figure 6 This is a hydraulic circuit diagram showing the structure of the main part of the shock absorber according to the first embodiment of the present invention.

[0022] Figure 7 It is a cross-sectional view showing the structure of the main part of the shock absorber according to the second embodiment of the present invention.

[0023] Figure 8 It is a cross-sectional view showing the structure of a main part of a shock absorber according to a third embodiment of the present invention.

[0024] Fig. 9 It is a bottom view showing a pilot housing of a shock absorber according to a third embodiment of the present invention.

[0025] Fig.10 It is a hydraulic circuit diagram showing the structure of the main part of the shock absorber according to the third embodiment of the present invention.

[0026] Fig.11It is a cross-sectional view showing another application example of the structure of the shock absorber according to the third embodiment of the present invention.

[0027] Fig.12 It is a cross-sectional view showing the structure of the main part of another application example of the structure of the shock absorber according to the third embodiment of the present invention. DETAILED DESCRIPTION

[0028] [First embodiment]

[0029] Below, refer to Figure 1 to Figure 6 The shock absorber of the first embodiment is described. Figure 1 to Figure 4 , Figure 6 to Figure 8 , Figure 10 to Figure 12 Set the upper side of Figure 1 to Figure 4 , Figure 6 to Figure 8 , Figure 10 to Figure 12 The lower side in is set as “lower” for explanation.

[0030] like Figure 1 As shown, the buffer 1 is a multi-cylinder type hydraulic buffer. The buffer 1 is used in a suspension device of a vehicle. The buffer 1 has a cylinder 2 in which oil L as a working fluid is sealed. The cylinder 2 has an inner cylinder 3 and an outer cylinder 4. The inner cylinder 3 is cylindrical. The outer cylinder 4 is cylindrical with a bottom. The inner diameter of the outer cylinder 4 is larger than the outer diameter of the inner cylinder 3. The inner cylinder 3 is arranged on the inner side of the outer cylinder 4. The central axis of the inner cylinder 3 is consistent with the central axis of the outer cylinder 4. A storage chamber 6 is provided between the inner cylinder 3 and the outer cylinder 4.

[0031] The outer cylinder 4 has a main body part 11 and a bottom part 12. The main body part 11 is cylindrical. The bottom part 12 is a bottomed cylindrical shape. The bottom part 12 is fitted into the lower side of the main body part 11 and fixed to the main body part 11 by welding. The bottom part 12 blocks the lower part of the main body part 11. A mounting hole 13 is fixed by welding on the outer side of the bottom part 12 opposite to the main body part 11 in the axial direction thereof.

[0032] The buffer 1 includes a piston 18. The piston 18 is slidably fitted in the inner tube 3 of the cylinder 2. The piston 18 divides the inner tube 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 closer to the side opposite to the bottom member 12 than the piston 18. In the axial direction of the cylinder 2, the lower chamber 20 is closer to the bottom member 12 than the piston 18. Oil L as a working fluid is sealed in the upper chamber 19 and the lower chamber 20 in the inner tube 3. Oil L and gas G as a working fluid are sealed in the storage chamber 6 between the inner tube 3 and the outer tube 4.

[0033] The buffer 1 includes a piston rod 21. One end side of the piston rod 21 in the axial direction is arranged in the inner tube 3 of the cylinder 2. The one end of the piston rod 21 is connected to the piston 18. The other end side of the piston rod 21 in the axial direction opposite to the one end extends from the cylinder 2 to the outside of the cylinder 2. The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 and the piston rod 21 move integrally. In the buffer 1, the stroke in which the piston rod 21 moves in the direction of increasing the amount of protrusion from the cylinder 2 is an extension stroke in which the entire length is extended. In the buffer 1, the stroke in which the piston rod 21 moves in the direction of reducing the amount of protrusion from the cylinder 2 is a shortening stroke in which the entire length is shortened. In the buffer 1, in the extension stroke, the piston 18 moves to the upper chamber 19 side. In the shortening stroke, the piston 18 moves to the lower chamber 20 side in the shortening stroke.

[0034] A rod guide 22 is fitted on the upper opening side of the inner tube 3 and the upper opening side of the outer tube 4. A sealing member 23 is fitted on the upper side of the outer tube 4 than the rod guide 22. A disk 24 is fitted on the upper side of the outer tube 4 than the sealing member 23. The rod guide 22 and the sealing member 23 are both annular. The disk 24 is a circular flat plate with a constant thickness and a hole. The disk 24 abuts against the outer peripheral side of the sealing member 23. The piston rod 21 slides relative to the rod guide 22 and the sealing member 23 along their axial directions. The piston rod 21 extends from the inside of the cylinder 2 to the outside of the cylinder 2 than the sealing member 23.

[0035] The rod guide 22 restricts the movement of the piston rod 21 in the radial direction relative to the inner tube 3 and the outer tube 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 tube 3. As a result, 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 in such a manner that the piston rod 21 can move in the axial direction of the piston rod 21. The outer peripheral portion of the sealing member 23 is in close contact with the outer tube 4. The inner peripheral portion of the sealing member 23 is in close contact with the outer peripheral portion of the piston rod 21. The piston rod 21 moves in the axial direction of the sealing member 23 relative to the sealing member 23. The sealing member 23 suppresses the oil L in the inner tube 3 and the high-pressure gas and oil L in the storage chamber 6 from leaking to the outside.

[0036] The upper portion of the outer periphery of the rod guide 22 has a larger diameter than the lower portion of the outer periphery. The rod guide 22 is fitted into the inner periphery of the upper end of the inner tube 3 at the lower portion with a smaller diameter. The rod guide 22 is fitted into the inner periphery of the upper portion of the outer tube 4 at the upper portion with a larger diameter. A bottom valve 25 is provided on the bottom member 12 of the outer tube 4. The bottom valve 25 is positioned radially relative to the outer tube 4. The bottom valve 25 divides the lower chamber 20 and the storage chamber 6. The inner periphery of the lower end of the inner tube 3 is fitted into the bottom valve 25. The upper end portion of the outer tube 4 is tightened radially inwardly of the outer tube 4. The sealing member 23 is clamped together with the disc 24 by the tightened portion and the rod guide 22, and is thereby fixed to the cylinder 2.

[0037] The piston rod 21 includes 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 arranged in the cylinder 2. The piston rod 21 is mounted with the piston 18 on the mounting shaft portion 28. The main shaft portion 27 of the piston rod 21 slides relative to the rod guide 22 and the sealing member 23. The main shaft portion 27 includes a shaft step portion 29. The shaft step portion 29 is provided at the end of the main shaft portion 27 on the mounting shaft portion 28 side. The shaft step portion 29 expands in a direction orthogonal to the central axis of the piston rod 21.

[0038] A passage groove 30 is formed on the outer periphery of the mounting shaft portion 28 of the piston rod 21. The passage groove 30 is formed by cutting the outer periphery of the mounting shaft portion 28 in a plane parallel to the central axis of the mounting shaft portion 28. The passage groove 30 extends in the axial direction of the mounting shaft portion 28. The passage groove 30 is formed at a plurality of locations, specifically two locations, at equal intervals in the circumferential direction of the mounting shaft portion 28. An external thread 31 is formed on the outer periphery of the end portion of the mounting shaft portion 28 on the opposite side of the main shaft portion 27 in the axial direction of the mounting shaft portion 28 than the passage groove 30.

[0039] In the shock absorber 1, for example, the portion of the piston rod 21 protruding from the cylinder 2 is arranged at the upper part and connected to the vehicle body. At this time, in the shock absorber 1, the mounting hole 13 provided on the cylinder 2 side is arranged at the lower part and connected to the wheel side of the vehicle. In the case where the shock absorber 1 is a single-tube type rather than a multi-tube type, the cylinder 2 side may be connected to the vehicle body in reverse. In this case, the piston rod 21 of the shock absorber 1 is connected to the wheel side.

[0040] In a vehicle, as the vehicle travels, the wheels vibrate relative to the vehicle body. Then, in the shock absorber 1, the positions of the cylinder 2 and the piston rod 21 change relative to each other in accordance with the vibration. This change is suppressed by the fluid resistance of the flow path provided in the shock absorber 1. As described below, the fluid resistance of the flow path provided in the shock absorber 1 is configured to be different depending on the speed and amplitude of the above-mentioned vibration. By suppressing the vibration by the shock absorber 1, the ride feeling of the vehicle can be improved.

[0041] In addition, in the vehicle, in addition to the vibration generated by the wheels relative to the vehicle body, the inertial force and centrifugal force generated in the vehicle body as the vehicle travels also act between the cylinder 2 and the piston rod 21. For example, the driving direction changes by operating the steering wheel, thereby generating centrifugal force in the vehicle body. Then, the force based on the centrifugal force acts between the cylinder 2 and the piston rod 21. As described below, the buffer 1 has good characteristics with respect to the vibration based on the force generated in the vehicle body as the vehicle travels. The buffer 1 can obtain higher driving stability in the vehicle.

[0042] The buffer 1 has a damping force generating mechanism 33. The damping force generating mechanism 33 includes a piston 18, which is Figure 2 The structure shown.

[0043] The piston 18 has a piston body 35 and a sliding member 36. The piston body 35 is made of metal and has a circular ring shape. The piston body 35 of the piston 18 is fitted into the mounting shaft portion 28 of the piston rod 21. The sliding member 36 is made of synthetic resin and has a circular ring shape. The sliding member 36 is integrally mounted on the outer peripheral surface of the piston body 35. The piston 18 slides relative to the inner tube 3 in a state where the sliding member 36 is in contact with the inner tube 3.

[0044] The piston body 35 is provided with a passage hole 37, a passage groove 38, a passage hole 39, and a passage groove 40. The passage hole 37 penetrates the piston body 35 in the axial direction of the piston body 35. A plurality of passage holes 37 are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35. The passage hole 39 penetrates the piston body 35 in the axial direction of the piston body 35. A plurality of passage holes 39 are formed in the piston body 35 at intervals in the circumferential direction of the piston body 35. In the piston body 35, the passage holes 37 and the passage holes 39 are formed alternately at equal intervals in the circumferential direction of the piston body 35, one passage hole 37 and one passage hole 39.

[0045] 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 the passage holes 37 are open to the passage groove 38 on the 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 on the opposite side to the passage groove 38 in the axial direction. All the passage holes 39 are open to the passage groove 40 on the end side opposite to the passage groove 38 in the axial direction of the piston body 35. The ends of the plurality of passage holes 37 on the opposite side to the passage groove 38 in the axial direction of the piston body 35 are open to the outside of the passage groove 40 in the radial direction of the piston body 35. The ends of the plurality of passage holes 39 on the opposite side to the passage groove 40 in the axial direction of the piston body 35 are open to the outside of the passage groove 38 in the radial direction of the piston body 35. In the piston 18, the inner sides of the plurality of passage holes 37 and the inner sides of the passage grooves 38 are piston-side passages 43. In the piston 18, the inner sides of the plurality of passage holes 39 and the inner sides of the passage grooves 40 are piston-side passages 44.

[0046] The damping force generating mechanism 33 includes 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 arranged on the lower chamber 20 side in the axial direction of the piston 18. Thus, during the extension stroke, the piston 18 moves in one direction, that is, to the upper chamber 19 side, and the piston side passage 43 causes the oil L to move from the upper chamber 19 on one side toward the lower chamber 20 on the other side via the opened first valve mechanism 41. The first valve mechanism 41 suppresses the flow of the oil L generated at this time from the piston side passage 43 to the lower chamber 20, thereby generating damping force.

[0047] The damping force generating mechanism 33 includes a first valve mechanism 42 provided in a piston side passage 44. The first valve mechanism 42 generates a damping force by opening and closing the piston side passage 44. The first valve mechanism 42 is arranged on the upper chamber 19 side in the axial direction of the piston 18. Thus, when the stroke is shortened, the piston side passage 44 allows the oil L to flow from the lower chamber 20 to the upper chamber 19 via the opened first valve mechanism 42 by the movement of the piston 18 toward the lower chamber 20. The first valve mechanism 42 suppresses the flow of the oil L generated at this time from the piston side passage 44 to the upper chamber 19, thereby generating a damping force.

[0048] The piston body 35 is in the shape of a disk having a hole, and the mounting shaft portion 28 of the piston rod 21 is fitted into the inner circumference thereof.

[0049] The piston body 35 includes a 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 body portion 50 is provided at an intermediate portion in the axial direction of the piston body 35. The inner seat portion 51 and the valve seat portion 53 are provided at an end portion on the lower chamber 20 side in the axial direction of the piston body 35. The inner seat portion 55 and the valve seat portion 57 are provided at an end portion on the upper chamber 19 side in the axial direction of the piston body 35.

[0050] The inner seat portion 51 is annular and is provided on the inner circumference 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 .

[0051] The valve seat portion 53 is annular. The valve seat portion 53 is arranged on the outside of the inner seat portion 51 in the radial direction of the piston body 35. The valve seat portion 53 protrudes from the main body 50 to the lower chamber 20 side in the axial direction of the piston body 35. The front end surface of the protruding side of the valve seat portion 53 is higher than the front end surface of the protruding side of the inner seat portion 51 in the axial direction of the piston body 35. The valve seat portion 53 is arranged on the outside of the piston body 35 in the radial direction than the opening of the passage groove 38 on the lower chamber 20 side. The valve seat portion 53 constitutes a part of the first valve mechanism 41.

[0052] The inner seat portion 55 is annular and is provided on the inner circumference of the main body portion 50 , and protrudes from the main body portion 50 toward the upper chamber 19 side in the axial direction of the piston body 35 .

[0053] The valve seat portion 57 is annular. The valve seat portion 57 is arranged on the outside of the inner seat portion 55 in the radial direction of the piston body 35. The valve seat portion 57 protrudes from the main body 50 to the upper chamber 19 side in the axial direction of the piston body 35. The front end surface of the protruding side of the valve seat portion 57 is higher in the protruding direction in the axial direction of the piston body 35 than the front end surface of the protruding side of the inner seat portion 55. The valve seat portion 57 is arranged on the outside of the piston body 35 in the radial direction than the opening of the passage groove 40 on the upper chamber 19 side. The valve seat portion 57 constitutes a part of the first valve mechanism 42.

[0054] like Figure 3 As shown, the damping force generating mechanism 33 is on the side of the inner seat portion 51 in the axial direction of the piston 18, and has a disk 70, a disk 71, a first damping valve 72 (damping force generating component), a disk 73, multiple (specifically four) disks 74, multiple (specifically three) disks 75, a disk 76, a disk 77, a limiting disk 78 (limiting component), a disk 79, a pilot housing 81 (force generating component), a second damping valve 84 composed of multiple (specifically three) disks 83, a disk 85, a disk 86 and an annular component 87 in sequence in the axial direction of the piston 18 from the inner seat portion 51 side.

[0055] The damping force generating mechanism 33 includes a disk 91 and a disk 92 between the limiting disk 78 and the pilot housing 81. The disks 91 and 92 are arranged to surround the disk 79 on the radially outer side of the disk 79. Of the disks 91 and 92, the disk 91 is provided on the limiting disk 78 side, and the disk 92 is provided on the opposite side to the limiting disk 78.

[0056] The disks 70, 71, 73 to 77, 79, 83, 85, 86, 91, 92, the limiting disk 78, the pilot housing 81, and the annular member 87 are all made of metal. The disks 70, 71, 73 to 77, 79, 83, 85, 86, 91, 92, and the annular member 87 are all circular flat plates with holes of a constant thickness. The disks 70, 71, 73 to 77, 79, 83, 85, 86, 91, 92 are formed by stamping. The first damping valve 72, the limiting disk 78, and the pilot housing 81 are all annular. The disks 70, 71, 73 to 77, 79, 83, 85, 86, the first damping valve 72, the limiting disk 78, the pilot housing 81, and the annular member 87 are all fitted with the mounting shaft portion 28 of the piston rod 21 inside.

[0057] The piston 18 , the disks 70 , 71 , 73 to 77 , 79 , 83 , the first damping valve 72 , the restricting disk 78 , and the pilot housing 81 cover the passage groove 30 of the piston rod 21 , and form a pilot chamber 95 in the passage groove 30 .

[0058] The pilot housing 81 is in the shape of a bottomed cylinder. The pilot housing 81 is integrally formed by sintering so as to be seamless as a whole. The pilot housing 81 includes a bottom 101 and a cylindrical portion 102 .

[0059] The bottom 101 is a perforated circular plate, 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 101 to one side along the axial direction of the bottom 101. The side of the pilot housing 81 opposite to the bottom 101 in the axial direction of the cylindrical portion 102 is an opening 103. In other words, the pilot housing 81 is a bottomed cylindrical shape having an opening 103 at one end in the axial direction.

[0060] 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 .

[0061] The bottom body portion 111 is a circular plate with a hole, so that the mounting shaft portion 28 of the piston rod 21 is fitted into the inner circumference thereof. Figure 4 As shown in FIG. 1 , a passage hole 121 is formed in the bottom body portion 111 and passes through the bottom body portion 111 in the axial direction of the bottom body portion 111. Figure 5 As shown, the bottom body portion 111 is provided with a plurality of (specifically, four) passage holes 121 at equal intervals in the circumferential direction of the bottom body portion 111 .

[0062] like Figure 3 and Figure 4 As shown, the inner seat portion 112 is formed on the inner circumferential side of the bottom body portion 111. The inner seat portion 112 is annular. The inner seat portion 112 protrudes from the bottom body portion 111 in the axial direction of the bottom body portion 111 to the same side as the cylindrical portion 102. The inner seat portion 112 is formed with a passage groove 124 that penetrates the inner seat portion 112 in the radial direction of the inner seat portion 112.

[0063] The valve seat portion 113 is formed continuously with the inner seat portion 112 at a position further outward than the inner seat portion 112 in the radial direction of the bottom body portion 111. The valve seat portion 113 is annular. The valve seat portion 113 protrudes from the bottom body portion 111 in the axial direction of the bottom body portion 111 to the same side as the inner seat portion 112. In the axial direction of the pilot housing 81, the height of the front end surface of the protruding side of the valve seat portion 113 is lower than the height of the front end surface of the protruding side of the inner seat portion 112, and is equal to the height of the groove bottom surface of the passage groove 124.

[0064] The outer seat portion 114 is formed continuously with the cylindrical portion 102 at the inner side of the cylindrical portion 102 in the radial direction of the bottom body portion 111. The outer seat portion 114 is formed separately from the valve seat portion 113 at the outer side of the valve seat portion 113 in the radial direction of the bottom body portion 111. 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 to the same side as the inner seat portion 112 and the valve seat portion 113. In the axial direction of the pilot housing 81, the height of the front end surface of the protruding side of the outer seat portion 114 is slightly lower than the height of the front end surface of the protruding side of the valve seat portion 113.

[0065] The bottom portion 101 is formed with an annular recess 125 which is recessed from the cylindrical portion 102 side in the axial direction to the side opposite to the cylindrical portion 102 by the bottom body portion 111, the valve seat portion 113 and the outer seat portion 114. The annular recess 125 is annular and extends in the circumferential direction of the bottom portion 101. The annular recess 125 is recessed from the front end surface of the protruding side of the valve seat portion 113 and the front end surface of the protruding side of the outer seat portion 114 to the side opposite to the cylindrical portion 102 along the axial direction of the pilot housing 81. 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 at the bottom surface of the annular recess 125.

[0066] The inner seat portion 115 is formed on the inner circumference of the bottom body portion 111. The inner seat portion 115 is annular. The inner seat portion 115 protrudes from the inner circumference of the bottom body portion 111 to the side opposite to the inner seat portion 112 in the axial direction of the bottom body portion 111. Figure 3 As shown in FIG. 1 , a passage groove 132 is formed on the inner seat portion 115 and passes through the inner seat portion 115 in the radial direction of the inner seat portion 115. Figure 5 As shown, the inner seat portion 115 is provided with a plurality of (specifically, four) passage grooves 132 at equal intervals in the circumferential direction of the inner seat portion 115 .

[0067] The outer seat portion 116 is formed at the outer side of the inner seat portion 115 in the radial direction of the bottom body portion 111. Figure 3 As shown, the outer seat portion 116 protrudes from the bottom body portion 111 to the same side as the inner seat portion 115 in the axial direction of the bottom body portion 111 on the radially outer side of the inner seat portion 115. Figure 5 As shown, the outer seat portion 116 is a petal-shaped seat that is not circular. The outer seat portion 116 has a plurality of (specifically, four) seat forming portions 133. These seat forming portions 133 are of the same shape and are arranged at equal intervals in the circumferential direction of the pilot housing 81. The plurality of seat forming portions 133 extend radially from the inner seat portion 115. Figure 3As shown, in the axial direction of the pilot housing 81 , the front end surfaces of the plurality of seat forming portions 133 opposite to the bottom body portion 111 are located at the same position as the front end surface of the inner seat portion 115 opposite to the bottom body portion 111 .

[0068] A passage recess 134 is formed inside each seat forming portion 133. Figure 5 As shown, the passage recess 134 is formed by being surrounded by a portion of the inner seat portion 115 and the seat forming portion 133. Figure 3 As shown, the passage recess 134 is recessed from the front end surface of the protruding side of the inner seat portion 115 and the front end surface of the protruding side of the seat forming portion 133 along the axial direction of the pilot housing 81. The bottom surface of the passage recess 134 is formed by the bottom body portion 111. Figure 5 As shown, a passage recess 134 is formed inside all the seat forming parts 133. In the circumferential direction of the pilot housing 81, each passage recess 134 and the passage groove 132 of the inner seat portion 115 are aligned in phase. The passage groove 132 is provided in the inner seat portion 115 so as to open to the inside of each passage recess 134.

[0069] The passage hole 121 is arranged between the seat forming parts 133 and the seat forming parts 133 adjacent to each other in the circumferential direction of the pilot housing 81. Thus, the passage hole 121 is arranged outside the outer seat part 116. In the pilot housing 81, there are four portions between the seat forming parts 133 and the seat forming parts 133 adjacent to each other in the circumferential direction, and the passage hole 121 is provided in each of these four portions.

[0070] Figure 3 and Figure 4 The outer diameter of the disk 70 shown is constant throughout the entire circumference. The disk 70 has an outer diameter larger than the outer diameter of the inner seat portion 51 of the piston 18. A notch 141 is formed in the disk 70. The notch 141 extends radially outward from the inner peripheral edge portion of the disk 70 that is fitted in the mounting shaft portion 28. The notch 141 penetrates the disk 70 in the axial direction of the disk 70. The notch 141 of the disk 70, the piston 18, and the disk 71 together constitute an introduction port 142.

[0071] The outer diameter of the disk 71 is constant throughout the entire circumference, and the inner diameter of the disk 71 is also constant throughout the entire circumference. The outer diameter of the disk 71 is smaller than the outer diameter of the disk 70. The disk 71 is disposed radially inward of the outer end of the notch 141 of the disk 70, and together with the notch 141, forms the introduction port 142.

[0072] The first damping valve 72 is composed of a disk 151 and a sealing member 152 .

[0073] The disk 151 is made of metal and is a circular flat plate with a hole of a constant thickness. The disk 151 is formed by press forming. The outer diameter of the disk 151 is constant throughout the entire circumference, and the inner diameter of the disk 151 is also constant throughout the entire circumference. The outer diameter of the disk 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 on the inner circumference side of the disk 151. The disk 151 of the first damping valve 72 abuts against the valve seat portion 53.

[0074] The passage in the introduction port 142 of the disk 70 is always in communication with the piston-side passage 43 and the pilot chamber 95 .

[0075] The first damping valve 72 is opened and closed by the disc 151 being separated from and brought into contact with the valve seat portion 53. Figure 3 The piston-side passage 43 is shown with its opening on the lower chamber 20 side.

[0076] The sealing member 152 is made of an elastic material having sealing properties, specifically, rubber. The sealing member 152 is annular. The sealing member 152 is fixed to the outer peripheral side of the disk 151. The sealing member 152 is fitted to the inner peripheral surface of the opening 103 side of the cylindrical portion 102 of the pilot housing 81 over the entire circumference. The sealing member 152 can slide in the axial direction relative to the inner peripheral surface of the cylindrical portion 102. The sealing member 152 always seals the gap between the first damping valve 72 and the cylindrical portion 102. The first damping valve 72 is arranged at the opening 103 of the pilot housing 81.

[0077] The outer diameter of the disk 73 is constant throughout the entire circumference, and the inner diameter of the disk 73 is also constant throughout the entire circumference. The outer diameter of the disk 73 is smaller than the minimum inner diameter of the sealing member 152. The outer diameter of the disk 73 is equal to the outer diameter of the disk 70.

[0078] The outer diameter of the disk 74 is constant throughout the entire circumference, and the inner diameter of the disk 74 is also constant throughout the entire circumference. The outer diameter of the disk 74 is smaller than the outer diameter of the disk 73. The outer diameter of the disk 74 is equal to the outer diameter of the disk 71.

[0079] The outer diameter of the disk 75 is constant throughout the entire circumference, and the inner diameter of the disk 75 is also constant throughout the entire circumference. The outer diameter of the disk 75 is larger than the outer diameter of the disk 73 and larger than the outer diameter of the disk 74.

[0080] The outer diameter of the disk 76 is constant throughout the entire circumference, and the inner diameter of the disk 76 is also constant throughout the entire circumference. The outer diameter of the disk 76 is larger than the outer diameter of the disk 75.

[0081] The inner diameter of the disk 77 is constant throughout the entire circumference. The outer diameter of the disk 77 is equal to the outer diameter of the disk 76. The disk 77 is formed with a cutout 155. The cutout 155 extends radially inward from the outer peripheral edge of the disk 77. The cutout 155 penetrates the disk 77 in the axial direction of the disk 77. In the cutout 155, the radially inner portion of the disk 77 is an arc shape that extends longer in the circumferential direction of the disk 77, and the length of the radially inner portion of the disk 77 in the circumferential direction of the disk 77 is longer than the length of the radially outer portion of the disk 77 in the circumferential direction of the disk 77. In the disk 77, a plurality of cutouts 155 are provided at equal intervals in the circumferential direction of the disk 77.

[0082] The limiting disk 78 has a disk 161 on the disk 77 side and a disk 162 on the opposite side of the disk 77 in the axial direction of the limiting disk 78. Both the disk 161 and the disk 162 are made of metal and are circular flat plates with holes of a constant thickness. Both the disk 161 and the disk 162 are formed by stamping.

[0083] The outer diameter of the disk 161 is constant throughout the entire circumference, and the inner diameter of the disk 161 is also constant throughout the entire circumference. The outer diameter of the disk 161 is larger than the outer diameter of the disks 76 and 77, and smaller than the inner diameter of the cylindrical portion 102 of the pilot housing 81. The mounting shaft portion 28 of the piston rod 21 is fitted on the inner circumferential side of the disk 161. A through hole 165 is formed in the disk 161, which passes through the disk 161 in the axial direction of the disk 161. The through hole 165 is in the shape of an arc extending long in the circumferential direction of the disk 161. The position of the through hole 165 in the radial direction of the disks 77 and 161 is aligned with the radial inner portion of the disk 77 in the shape of an arc extending long in the circumferential direction of the disk 77 in the cutout 155 of the disk 77. In the disk 161, a plurality of through holes 165 are provided at equal intervals in the circumferential direction of the disk 161. The passage in the through hole 165 is connected to the passage in the cutout 155 of the disk 77. The cutout 155 of the disk 77 and the through hole 165 of the disk 161 constitute a communication orifice 166 (second throttle mechanism).

[0084] The outer diameter of the disk 162 is constant throughout the entire circumference, and the inner diameter of the disk 162 is also constant throughout the entire circumference. The outer diameter of the disk 162 is slightly larger than the outer diameter of the disk 161, and smaller than the inner diameter of the cylindrical portion 102 of the pilot housing 81. The inner diameter of the disk 162 is larger than the inner diameter of the disk 161, and larger than the outer diameter of the valve seat portion 113 of the pilot housing 81. The disk 162 is coaxially arranged with the disk 161, and is arranged at the outer side of the through hole 165 in the radial direction of the disk 161. The disk 162 is integrated with the disk 161 by annular welding to the disk 161.

[0085] The outer diameter of the disk 79 is constant throughout the entire circumference, and the inner diameter of the disk 79 is also constant throughout the entire circumference. The outer diameter of the disk 79 is smaller than the inner diameter of the disk 162 of the limiting disk 78. The disk 79 is arranged on the inner side of the through hole 165 in the radial direction of the limiting disk 78. The outer diameter of the disk 79 is equal to the outer diameter of the inner seat portion 112 of the pilot housing 81.

[0086] The outer diameter of the disk 83 is constant throughout the entire circumference, and the inner diameter of the disk 83 is also constant throughout the entire circumference. The outer diameter of the disk 83 is equal to the outer diameter of the outer seat portion 116 of the pilot housing 81 .

[0087] The outer diameter of the disk 85 is constant throughout the entire circumference, and the inner diameter of the disk 85 is also constant throughout the entire circumference. The outer diameter of the disk 85 is smaller than the outer diameter of the disk 83.

[0088] The outer diameter of the disk 86 is constant throughout the entire circumference, and the inner diameter of the disk 86 is also constant throughout the entire circumference. The outer diameter of the disk 86 is smaller than the outer diameter of the disk 85. The outer diameter of the disk 86 is equal to the outer diameter of the inner seat portion 115 of the pilot housing 81.

[0089] The outer diameter of the annular member 87 is constant throughout the entire circumference, and the inner diameter of the annular member 87 is also constant throughout the entire circumference. The outer diameter of the annular member 87 is larger than the outer diameter of the disk 85, and smaller than the outer diameter of the disk 83. The thickness of the annular member 87 is thicker than the thickness of the disks 83 and 85, and the rigidity of the annular member 87 is higher than the rigidity of the disk 83.

[0090] The outer diameter of the disk 91 is constant throughout the entire circumference. The outer diameter of the disk 91 is slightly larger than the outer diameter of the disk 162 of the limiting disk 78, and slightly smaller than the inner diameter of the cylindrical portion 102 of the pilot housing 81. The inner diameter of the disk 91 is smaller than the outer diameter of the valve seat portion 113 of the pilot housing 81, and larger than the outer diameters of the inner seat portion 112 of the valve seat portion 113 and the disk 79. A cutout 171 is formed on the inner circumferential side of the disk 91. The cutout 171 extends radially outward from the inner circumferential edge of the disk 91. The cutout 171 penetrates the disk 91 in the axial direction of the disk 91.

[0091] The outer diameter of the disk 92 is constant throughout the entire circumference, and the inner diameter of the disk 92 is also constant throughout the entire circumference. The outer diameter of the disk 92 is equal to the outer diameter of the disk 91, and the inner diameter of the disk 92 is equal to the inner diameter of the disk 91. The outer diameter of the disk 92 is larger than the inner diameter of the outer seat portion 114 of the pilot housing 81.

[0092] The limiting disk 78 presses the outer peripheral sides of the disks 91 and 92 against the outer seat portion 114 of the pilot housing 81. At this time, the disk 162 of the limiting disk 78 abuts against the outer peripheral side of the disk 91, so that the outer peripheral side of the disk 92 abuts against the outer seat portion 114. The limiting disk 78, together with the disks 75 to 77, limits the outer peripheral sides of the disks 91 and 92 from being separated axially from the outer seat portion 114 of the pilot housing 81, that is, the valve is opened.

[0093] As described above, in the axial direction of the pilot housing 81, the height of the outer seat portion 114 in the protruding direction is lower than the height of the valve seat portion 113 in the protruding direction. Therefore, the disks 91 and 92 in the state of being pressed against the outer seat portion 114 by the limiting disk 78 are elastically deformed so that the inner circumference side is located on the disk 161 side closer to the limiting disk 78 than the outer circumference side in the axial direction, and the inner circumference side is pressed against the valve seat portion 113. At this time, the disk 92 is in contact with the valve seat portion 113 over the entire circumference.

[0094] The portion surrounded by the first damping valve 72, the disks 73 to 77, the limiting disk 78, and the pilot housing 81 is the main back pressure chamber 181. The portion surrounded by the limiting disk 78 and the disks 91 and 92 is the secondary back pressure chamber 182. The through hole 165 opens to the secondary back pressure chamber 182. The portion surrounded by the annular recess 125 of the pilot housing 81 and the disk 92 is the variable chamber 183.

[0095] A communication port 166 formed by the cutout 155 of the disk 77 and the through hole 165 of the disk 161 is provided between the primary back pressure chamber 181 and the secondary back pressure chamber 182. In other words, the secondary back pressure chamber 182 communicates with the primary back pressure chamber 181 via a passage in the communication port 166.

[0096] like Figure 4 As shown, the variable chamber 183 is connected to the lower chamber 20 via the passage in the passage hole 121 of the pilot housing 81. The volume of the variable chamber 183 is variable by the deformation of the disks 91 and 92. That is, if the disks 91 and 92 are deformed in a manner close to the bottom surface of the annular recess 125, the volume of the variable chamber 183 becomes smaller, thereby expanding the volume of the auxiliary back pressure chamber 182. If the disks 91 and 92 are deformed in a manner away from the bottom surface of the annular recess 125 from this state, the volume of the variable chamber 183 becomes larger, thereby reducing the volume of the auxiliary back pressure chamber 182.

[0097] The primary back pressure chamber 181, the communication port 166, and the secondary back pressure chamber 182 constitute a back pressure chamber 184. The bottomed cylindrical pilot housing 81 forms the back pressure chamber 184 together with the first damping valve 72 disposed on the opening 103 side.

[0098] When the pressure of the secondary back-pressure chamber 182 is higher than the pressure of the variable chamber 183, the disk 92 of the disks 91 and 92 contacts the valve seat portion 113 over the entire circumference. Thus, the disks 91 and 92 and the valve seat portion 113 restrict the flow of the oil L from the pilot chamber 95 and the secondary back-pressure chamber 182 to the variable chamber 183. When the pressure of the variable chamber 183 is higher than the pressure of the secondary back-pressure chamber 182, the disks 91 and 92 separate from the valve seat portion 113. Thus, the disks 91 and 92 and the valve seat portion 113 allow the oil L to flow from the variable chamber 183 to the pilot chamber 95 and the secondary back-pressure chamber 182. Thus, the disks 91 and 92 and the valve seat portion 113 constitute the check valve 191 that restricts the flow of the oil L from the pilot chamber 95 and the secondary back-pressure chamber 182 to the variable chamber 183 but allows the flow of the oil L from the variable chamber 183 to the pilot chamber 95 and the secondary back-pressure chamber 182.

[0099] The disk 91 and the disk 92 are deformed and moved in a substantially integral manner in an overlapping state. The disks 91 and 92 constitute a movable valve 192 (movable member) of the check valve 191. The valve 192 is provided at the bottom 101 of the pilot housing 81, and divides the variable chamber 183 on the side opposite to the back pressure chamber 184, thereby blocking the flow of the oil L from the back pressure chamber 184 to the variable chamber 183.

[0100] When the check valve 191 is opened, the inner peripheral portion of the deformed valve 192 approaches the disk 161 of the limiting disk 78, narrowing the flow path between it and the disk 161. The inner peripheral portion of the valve 192 and the disk 161 of the limiting disk 78 constitute a variable orifice 193 (first throttling mechanism, first throttling portion). The flow path cross-sectional area of ​​the variable orifice 193 is smaller than the flow path cross-sectional area of ​​the connecting orifice 166. The variable orifice 193 is provided between the pilot chamber 95 and the secondary back pressure chamber 182, and changes the cross-sectional area of ​​the flow path between the pilot chamber 95 and the secondary back pressure chamber 182 according to the deformation amount of the valve 192. That is, the greater the deformation amount of the valve 192, the narrower the flow path between the pilot chamber 95 and the secondary back pressure chamber 182 is made by the variable orifice 193. The variable orifice 193 includes a passage in the cutout 171 of the disk 91. When the disc 91 of the valve 192 abuts against the disc 161 of the limiting disc 78, the passage in the notch 171 of the disc 91 makes the flow path cross-sectional area in the variable orifice 193 a minimum value that is not 0. In this way, the valve 192 constitutes the variable orifice 193 that limits the inflow of the oil L from the variable chamber 183 to the auxiliary back pressure chamber 182. The valve 192 also serves as the check valve 191. The auxiliary back pressure chamber 182 is provided between the variable orifice 193 and the primary back pressure chamber 181.

[0101] The disk 151 of the first damping valve 72 is seated on the valve seat portion 53 of the piston 18. If the first damping valve 72 is unseated from the valve seat portion 53 of the piston 18, Figure 3 The piston side passage 43 shown in the figure allows the oil L to flow from the upper chamber 19 to the lower chamber 20 via the passage between the disk 151 and the valve seat portion 53. The piston side passage 43 and the passage between the disk 151 and the valve seat portion 53 constitute Figure 2 The first passage 201 that connects the upper chamber 19 and the lower chamber 20 is shown. The first damping valve 72 is provided in the first passage 201, and the flow of the oil L generated by the sliding of the piston 18 to the extension side is suppressed, thereby generating a damping force. The first damping valve 72 constitutes the first valve mechanism 41 together with the valve seat portion 53 of the piston 18. The first valve mechanism 41 performs a valve opening action when the upper chamber 19 is at the upstream pressure, and acts in a manner to suppress the flow of the oil L. The first passage 201 is a passage on the extension side for the oil L as the working fluid to flow from the upper chamber 19 on one side to the lower chamber 20 on the other side during the movement of the piston 18 to the upper chamber 19 side, that is, the extension stroke. The first valve mechanism 41 on the extension side, which is constituted by the valve seat portion 53 and the first damping valve 72, is provided in the first passage 201, and the flow of the oil L is suppressed by opening and closing the first passage 201 with the first damping valve 72, thereby generating a damping force. The first valve mechanism 41 can adjust the damping force by the pressure of the main back pressure chamber 181 of the back pressure chamber 184. The lower chamber 20 is located downstream of the first damping valve 72 in the flow direction of the oil L in the first passage 201 during the extension stroke.

[0102] like Figure 3 As shown, the outer diameter of the second damping valve 84 composed of a plurality of disks 83 is slightly larger than the maximum outer diameter of the front end surface of the outer seat portion 116. The second damping valve 84 can be seated / unseated relative to the outer seat portion 116.

[0103] The piston side passage 43, the passage in the introduction port 142 of the disk 70, the pilot chamber 95 on the piston rod 21 side, the passage in the variable port 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 Figure 2 A second passage 202 is shown which allows the upper chamber 19 and the lower chamber 20 to communicate with each other.

[0104] The second passage 202 is provided with a portion other than the piston side passage 43 shared with the first passage 201 in parallel with the first passage 201 so as to allow the upper chamber 19 and the lower chamber 20 to communicate with each other. Figure 3 The introduction orifice 142 , the pilot chamber 95 , the variable orifice 193 , the secondary back pressure chamber 182 , the communication orifice 166 , and the primary back pressure chamber 181 are shown.

[0105] The outer seat portion 116 and the second damping valve 84 constitute a second valve mechanism 205 that is provided in the second passage 202 and 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. The second damping valve 84 opens during the extension stroke and applies resistance to the flow of the oil L from the upper chamber 19 to the lower chamber 20 via the second passage 202. In other words, the second valve mechanism 205 suppresses the flow of the oil L from the upper chamber 19 to the lower chamber 20 to generate a damping force. The second valve mechanism 205 is a damping force generating mechanism on the extension side that is provided in the second passage 202 and generates a damping force by the flow of the oil L.

[0106] The back pressure chamber 184 causes the internal pressure to act on the first damping valve 72 in the direction of the piston 18, that is, in the valve closing direction in which the disk 151 is seated on the valve seat portion 53. The pilot housing 81 is a bottomed cylindrical shape, and forms the back pressure chamber 184 that generates the force in the valve closing direction in the first damping valve 72 disposed on the side of the opening portion 103. In other words, the back pressure chamber 184 generates the force in the valve closing direction in the first damping valve 72 that abuts against the valve seat portion 53 of the piston 18.

[0107] like Figure 4 As shown, a lower chamber communication passage 211 for communicating the variable chamber 183 with the lower chamber 20 is formed in the passage hole 121 provided at the bottom 101 of the pilot housing 81. The lower chamber communication passage 211 discharges the oil L in the variable chamber 183 to 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 communication passage 211 also form a second passage 202.

[0108] The valve 192 of the one-way valve 191 is provided between the lower chamber communication passage 211 and the variable chamber 183 and the back pressure chamber 184 and the pilot chamber 95 in an openable and closable manner. The valve 192 of the one-way valve 191 cuts off the flow of the 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, while the valve 192 of the one-way valve 191 is in contact with the valve seat portion 113 of the pilot housing 81. In addition, the valve 192 of the one-way valve 191 allows the flow of the 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, while the valve 192 of the one-way valve 191 is separated from the valve seat portion 113.

[0109] Here, if the pressure of the variable chamber 183, the lower chamber communication passage 211, and the lower chamber 20 side is higher than the pressure of the back pressure chamber 184 and the pilot chamber 95 side by a predetermined value or more, the valve 192 of the check valve 191 allows the oil L to flow from the lower chamber 20 to the back pressure chamber 184 and the pilot chamber 95 via the lower chamber communication passage 211 and the variable chamber 183. In a state where the pressure of the back pressure chamber 184 and the pilot chamber 95 side is higher than the pressure of the variable chamber 183, the lower chamber communication passage 211, and the lower chamber 20 side, the valve 192 of the check valve 191 restricts the flow of the oil L from the back pressure chamber 184 and the pilot chamber 95 to the lower chamber 20 via the variable chamber 183 and the lower chamber communication passage 211. In other words, the check valve 191 restricts the flow of the oil L in one direction from the back pressure chamber 184 and the pilot chamber 95 side to the lower chamber 20 side between the back pressure chamber 184 and the pilot chamber 95 and the lower chamber 20. On the other hand, the check valve 191 allows the flow of the oil L in the other direction from the lower chamber 20 side to the back pressure chamber 184 and the pilot chamber 95 side. The valve 192 of the check valve 191 is a valve member of the check valve 191 .

[0110] One-way valve 191 restricts the oil L from Figure 2 The upper chamber 19, the piston side passage 43, Figure 3 The passage in the inlet opening 142 of the disk 70, the pilot chamber 95 and the back pressure chamber 184 are shown to Figure 4 The one-way valve 191 allows the oil L to flow from the lower chamber 20, the lower chamber communication passage 211 and the variable chamber 183 through the back pressure chamber 184, the pilot chamber 95, the passage in the introduction port 142 of the disk 70 and the Figure 2 The piston side passage 43 is shown to flow to the upper chamber 19 .

[0111] The first valve mechanism 42 on the shortened side is on the inner seat portion 55 side in the axial direction of the piston 18, and has a disk 221, a disk 222, multiple (specifically, three) disks 223, a disk 224, a disk 225, and an annular member 226 in the axial direction of the piston 18. The disks 221 to 225 and the annular member 226 are made of metal and are circular flat plates with holes of a constant thickness. The disks 221 to 225 are formed by stamping. The disks 221 to 225 and the annular member 226 are all fitted with the mounting shaft portion 28 of the piston rod 21 on the inner side.

[0112] The disk 221 has an outer diameter that is equal to the outer diameter of the inner seat portion 55 of the piston 18 .

[0113] The disk 222 has an outer diameter slightly larger than that of the disk 221 .

[0114] The plurality of disks 223 constitute a 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.

[0115] The disk 224 has an outer diameter that is smaller than the outer diameter of the plurality of disks 223 and is equal to the outer diameter of the disk 221 .

[0116] The disk 225 has an outer diameter larger than that of the disk 224 .

[0117] The annular member 226 has an outer diameter larger than that of the disk 225 and smaller than that of the disk 223. The annular member 226 is thicker than the disk 223 and has higher rigidity than the disk 223. The annular member 226 abuts against the shaft step 29 of the piston rod 21.

[0118] The disk 225 and the annular member 226 suppress deformation of the first damping valve 231 in the opening direction by a predetermined amount or more.

[0119] The first damping valve 231 composed of a plurality of disks 223 constitutes the first valve mechanism 42 together with the valve seat portion 57 of the piston 18. The first damping valve 231 is unseated from the valve seat portion 57 and is opened. Then, the first damping valve 231 allows the oil L from the piston side passage 44 to flow to the upper chamber 19 through the space between the first damping valve 231 and the valve seat portion 57. The passage between the piston side passage 44 and the first damping valve 231 and the valve seat portion 57 becomes the first passage 232 on the shortening side through which the oil L in the lower chamber 20 flows as the piston 18 moves toward the lower chamber 20 side. The first passage 232 allows the oil L as the working fluid to flow out from the lower chamber 20 on one side toward the upper chamber 19 on the other side during the shortening stroke. The first valve mechanism 42 on the shortening side composed 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 suppressing the flow of the oil L by opening and closing the first passage 232 with the first damping valve 231 .

[0120] In addition, if Figure 6 As shown, the buffer 1 is provided with a fixing hole 235. The fixing hole 235 is connected via Figure 2 The piston 18 shown in the figure makes the upper chamber 19 and the lower chamber 20 always communicate. The fixed orifice 235 is formed by, for example, notching at least one of the valve seat portion 57 of the first valve mechanism 42 on the contraction side and the first damping valve 231. In addition, the fixed orifice 235 can also be formed by notching the valve seat portion 53 of the first valve mechanism 41 on the extension side, and both the extension side and the contraction side can also be combined.

[0121] Figure 4 The pilot housing 81 and the valve 192 shown in the figure constitute a frequency sensing mechanism 241 that senses the frequency of the reciprocating motion of the piston 18 (hereinafter referred to as the piston frequency) and makes the damping force variable. The frequency sensing mechanism 241 is composed of a portion that increases in the secondary back pressure chamber 182 when the disk 92 deforms in a manner close to the bottom surface of the annular recess 125, the variable chamber 183, and the valve 192 that divides them. The frequency sensing mechanism 241 is a pressure accumulator. The frequency sensing mechanism 241 is provided in the second passage 202 including the lower chamber communication passage 211. The valve 192 of the frequency sensing mechanism 241 moves and deforms according to the frequency of the reciprocating motion of the piston 18, and changes the capacity of the back pressure chamber 184 that is always connected to the upper chamber 19 and the capacity of the variable chamber 183 that is always connected to the lower chamber 20. The frequency sensing mechanism 241 has a valve 192 that is movably provided in the second passage 202 including the lower chamber communication passage 211. The frequency sensing mechanism 241 makes variable the force applied by the back pressure chamber 184 to the first damping valve 72 .

[0122] During the extension stroke, the pressure on the auxiliary back-pressure chamber 182 side of the back-pressure chamber 184 is higher than that on the variable chamber 183, the lower chamber connecting passage 211, and the lower chamber 20 side. As a result, the valve 192 receives the pressure from the auxiliary back-pressure chamber 182 and deforms toward the bottom surface of the annular recess 125. As a result, the volume of the back-pressure chamber 184 is expanded and the volume of the variable chamber 183 is reduced. In this way, the frequency sensing mechanism 241 is actuated when the upper chamber 19 is the upstream pressure, and acts in a manner that senses the piston frequency and makes the damping force variable. In other words, the frequency sensing mechanism 241 changes the volume of the variable chamber 183 through the movement caused by the deformation of the valve 192 during the extension stroke, resulting in a change in the volume of the back-pressure chamber 184.

[0123] During the shortening stroke, the pressure on the lower chamber 20, the lower chamber communication passage 211, and the variable chamber 183 side is higher than that on the secondary back pressure chamber 182 side. Therefore, the valve 192 is released from the valve seat portion 113 of the pilot housing 81, and the oil L flows from the lower chamber 20, the lower chamber communication passage 211, and the variable chamber 183 to the secondary back pressure chamber 182 and the pilot chamber 95. In other words, when the lower chamber 20 is at the upstream pressure, the check valve 191 provided in the second passage 202 including the lower chamber communication passage 211 performs a valve opening action to function in a manner that allows the oil L to flow.

[0124] During the shortening stroke, if the valve 192 of the check valve 191 is unseated 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 restricting disc 78. As a result, the flow of the oil L from the lower chamber 20 to the secondary back pressure chamber 182 via the lower chamber communication passage 211, the variable chamber 183, and the check valve 191 in the valve open state is suppressed. As a result, the pressure rise in the secondary back pressure chamber 182 is suppressed. In addition, at this time, since the communication orifice 166 is also provided between the secondary back pressure chamber 182 and the primary back pressure chamber 181, the communication orifice 166 acts to suppress the flow of the oil L from the secondary back pressure chamber 182 to the primary back pressure chamber 181. As a result, the pressure rise in the primary back pressure chamber 181 is further suppressed than the pressure rise in the secondary back pressure chamber 182. Thus, when the lower chamber 20 is at the upstream pressure, the variable orifice 193 provided downstream of the check valve 191 operates to suppress and control the flow of the working fluid, ie, the oil L, into the secondary back pressure chamber 182 and the primary back pressure chamber 181 .

[0125] In the piston rod 21, the mounting shaft portions 28 are sequentially overlapped on the shaft step portions 29 so that the mounting shaft portions 28 are inserted into the inner sides of the respective shaft step portions 29. Figure 2 The annular member 226, the disk 225, the disk 224, the plurality of disks 223, the disk 222, the disk 221, the piston 18, Figure 3 The disk 70, disk 71, first damping valve 72, disk 73, multiple disks 74, multiple disks 75, disk 76, disk 77, limiting disk 78, and disk 79 are shown. In addition, disks 91 and 92 are sequentially overlapped on the limiting disk 78. In this state, the pilot housing 81, multiple disks 83, disk 85, disk 86, and annular member 87 are sequentially overlapped on the disk 79 in such a manner that the mounting shaft portion 28 is inserted into the inner side of each.

[0126] In this state where the parts from the annular part 226 to the annular part 87 are overlapped, as shown in FIG. Figure 2 As shown, the nut 245 is screwed into the external thread 31 of the mounting shaft portion 28 of the piston rod 21 that protrudes from the annular member 87. Figure 3 and Figure 4In addition to the plates 91, 92 shown, the inner circumference of each or the entire inner circumference of the piston rod 21 is Figure 2 The shaft step portion 29 and the nut 245 shown are clamped and tightened in the axial direction.

[0127] In this state, if Figure 3 and Figure 4 As shown, the sealing member 152 of the first damping valve 72 is fitted into the cylindrical portion 102 of the pilot housing 81, and the disks 73 to 77, 79, the limiting disk 78, and the disks 91, 92 are arranged in the pilot housing 81. The limiting disk 78 presses the outer peripheral side of the disks 91, 92 against the outer seat portion 114 of the pilot housing 81 in a manner that does not allow axial movement, and makes the inner peripheral side of the disks 91, 92 abut against the valve seat portion 113 of the pilot housing 81. In this state, the disks 91, 92 are slightly elastically deformed and pressed against the valve seat portion 113.

[0128] like Figure 1 As shown, the bottom valve 25 is provided between the bottom member 12 of the inner tube 3 and the outer tube 4. The bottom valve 25 includes a bottom valve member 251, a disk valve 252, a disk valve 253, and a mounting pin 254. The bottom valve 25 is placed on the bottom member 12 at the bottom valve member 251, and is fitted to the inner tube 3 at the bottom valve member 251. The bottom valve member 251 separates the lower chamber 20 and the storage chamber 6. The disk valve 252 is provided on the lower side of the bottom valve member 251, that is, on the storage chamber 6 side. The disk valve 253 is provided on the upper side of the bottom valve member 251, that is, on the lower chamber 20 side. The mounting pin 254 mounts the disk valve 252 and the disk valve 253 to the bottom valve member 251.

[0129] The bottom valve member 251 is annular, and the mounting pin 254 is inserted in the radial center of the bottom valve member 251. A plurality of passage holes 255 and a plurality of passage holes 256 are formed in the bottom valve member 251. The plurality of passage holes 255 allow the oil L to flow between the lower chamber 20 and the storage chamber 6. The plurality of passage holes 256 are arranged on the outer side of the plurality of passage holes 255 in the radial direction of the bottom valve member 251. The plurality of passage holes 256 allow the oil L to flow between the lower chamber 20 and the storage chamber 6. The disk valve 252 on the storage chamber 6 side allows the oil L to flow from the lower chamber 20 to the storage chamber 6 via the passage hole 255. On the other hand, the disk valve 252 inhibits the oil L from flowing from the storage chamber 6 to the lower chamber 20 via the passage hole 255. The disk valve 253 allows the oil L to flow from the storage chamber 6 to the lower chamber 20 via the passage hole 256. On the other hand, the disk valve 253 suppresses the flow of the oil L from the lower chamber 20 to the reservoir chamber 6 via the passage hole 256 .

[0130] The disk valve 252 and the bottom valve member 251 together constitute a damping valve mechanism 257. The damping valve mechanism 257 opens during the contraction stroke of the shock absorber 1 to allow the oil L to flow from the lower chamber 20 to the reservoir chamber 6 and generate a damping force. The disk valve 253 and the bottom valve member 251 together constitute a suction valve mechanism 258. The suction valve mechanism 258 opens during the extension stroke of the shock absorber 1 to allow the oil L to flow from the reservoir chamber 6 to the lower chamber 20. The suction valve mechanism 258 mainly functions to allow the liquid to flow from the reservoir chamber 6 to the lower chamber 20 without substantially generating a damping force in a manner that compensates for the insufficient amount of liquid generated by the extension of the piston rod 21 from the cylinder 2.

[0131] If the structure of the damping force generating mechanism 33 described above is represented as a hydraulic circuit diagram, it becomes Figure 6 As shown.

[0132] The damping force generating mechanism 33 has a fixed orifice 235 that always connects the upper chamber 19 and the lower chamber 20. 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 in the second passage 202, a pilot chamber 95 that is closer to the lower chamber 20 side than 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 secondary back pressure chamber 182 communicating with the variable orifice 193, a communicating orifice 166 communicating with the secondary back pressure chamber 182, and a main back pressure chamber 181 communicating with the communicating orifice 166 in the second passage 202. The damping force generating mechanism 33 has a frequency sensing mechanism 241 between the secondary back pressure chamber 182 and the lower chamber 20 in the second passage 202. In the damping force generating mechanism 33, the pressure of the main back pressure chamber 181 is applied to the first valve mechanism 41 as a back pressure. 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 communicating the lower chamber 20 and the upper chamber 19, and a first valve mechanism 42 provided in the first passage 232.

[0133] Next, the operation of the shock absorber 1 including the damping force generating mechanism 33 will be described.

[0134] {In the extension stroke, the piston frequency is low and the piston speed is slower than the first specified value v1 in the low-frequency slightly low-speed region x1}

[0135] In the low-frequency and slightly low-speed range x1, the first valve mechanism 41 and the second valve mechanism 205 do not open the valves. In addition, the oil L from the upper chamber 19 flows to the auxiliary back pressure chamber 182 of the back pressure chamber 184 via the piston side passage 43, the passage in the introduction port 142 of the disk 70, and the pilot chamber 95. As a result, the valve 192 of the frequency sensing mechanism 241 moves to the bottom surface side of the annular recess 125. In the low-frequency and slightly low-speed range x1, the piston frequency is low and the piston 18 has a large stroke. Therefore, at the beginning of the stroke, a large amount of oil L is introduced from the upper chamber 19 to the back pressure chamber 184. Therefore, the valve 192 of the frequency sensing mechanism 241 moves and deforms to the bottom surface side of the annular recess 125 to the vicinity of the limit, and then becomes less likely to deform (high spring region). On the other hand, in the low-frequency and slightly low-speed range x1, the oil L from the upper chamber 19 flows to the lower chamber 20 via the fixed port 235. Thus, in the low frequency and slightly low speed range x1, a damping force with an orifice characteristic (damping force is substantially proportional to the square of the piston speed) is generated. Therefore, in the low frequency and slightly low speed range x1, the increase rate of the damping force relative to the increase of the piston speed is relatively high.

[0136] {In the extension stroke, the piston frequency is low frequency and the piston speed is greater than the first predetermined value v1 and slower than the second predetermined value v2 in the low frequency and low speed region x2}

[0137] In the low-frequency and low-speed range x2, similarly to the low-frequency and slightly low-speed range x1, the oil L from the upper chamber 19 flows to the upper chamber 19 via the fixed orifice 235, and causes the valve 192 of the frequency sensing mechanism 241 to move and deform greatly toward the bottom surface side of the annular recess 125. After that, the oil L from the upper chamber 19 via the piston side passage 43, the passage in the introduction orifice 142 of the disk 70, and the pilot chamber 95 becomes less likely to be introduced into the back pressure chamber 184. In the low-frequency and low-speed range x2, the pressure of the back pressure chamber 184 is higher than that in the low-frequency and slightly low-speed range x1. Therefore, in the low-frequency and low-speed range x2, the oil L from the upper chamber 19 opens the second damping valve 84 of the second valve mechanism 205 via the piston side passage 43, the passage in the introduction orifice 142 of the disk 70, and the pilot chamber 95, and flows to the lower chamber 20. That is, 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 and low-speed region x2, a damping force of valve characteristics (damping force is approximately proportional to piston speed) is generated. Therefore, in the low-frequency and low-speed region x2, the rate of increase of the damping force relative to the increase of the piston speed is lower than that in the low-frequency and slightly low-speed region x1. In this low-frequency and low-speed region x2, since the valve 192 of the frequency sensing mechanism 241 moves and deforms to the vicinity of the limit, the pressure of the back pressure chamber 184 becomes high pressure. Therefore, for the first damping valve 72 of the first valve mechanism 41, the force from the back pressure chamber 184 is large, thereby limiting its valve opening.

[0138] {In the extension stroke, the piston frequency is low frequency and the piston speed is a low frequency medium-high speed region x3 that is greater than the second predetermined value v2}

[0139] In the low-frequency, medium-high speed range x3, similarly to the low-frequency, slightly low-speed range x1, the oil L from the upper chamber 19 flows to the upper chamber 19 via the fixed orifice 235, and opens the second damping valve 84 of the second valve mechanism 205, and flows to the lower chamber 20 via the piston-side passage 43, the passage in the introduction orifice 142 of the disk 70, and the pilot chamber 95. In the low-frequency, medium-high speed range x3, the oil L thus flows to the lower chamber 20 via the second passage 202, and thus the pressure rise in the back pressure chamber 184 caused by the oil L introduced from the pilot chamber 95 to the back pressure chamber 184 can be suppressed. In contrast, since the force in the valve opening direction applied from the piston-side passage 43 to the first valve mechanism 41 increases, the oil L from the upper chamber 19 flows to the lower chamber 20 via the piston-side passage 43, opens the first damping valve 72 of the first valve mechanism 41. That is, 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-speed range x3, the rate of increase of the damping force with respect to the increase in the piston speed is lower than that in the low-frequency, low-speed range x2.

[0140] {In the extension stroke, the piston frequency is higher than the above low frequency and the piston speed is slower than the third specified value v3 in the high-frequency slightly low-speed region x4}

[0141] In the high-frequency and slightly low-speed region x4, the first valve mechanism 41 and the second valve mechanism 205 do not open the valves. Also, similar to the low-frequency and slightly low-speed region x1, the oil L from the upper chamber 19 flows to the upper chamber 19 via the fixed orifice 235, and flows to the auxiliary 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 sensing mechanism 241 moves and deforms toward the bottom surface side of the annular recess 125. In the high-frequency and slightly low-speed region x4, the piston frequency is high frequency and the stroke of the piston 18 is small. Therefore, compared with the low-frequency and slightly low-speed region x1, the oil L introduced from the upper chamber 19 to the back pressure chamber 184 is less. As a result, the valve 192 of the frequency sensing mechanism 241 will not deform to the vicinity of the limit and is easy to deform (low spring region). As a result, the oil L introduced from the upper chamber 19 to the back pressure chamber 184 can be absorbed by the movement and deformation of the valve 192. Therefore, in the high-frequency and slightly low-speed range x4, the rising rate of the damping force relative to the increase in the piston speed becomes higher, but the damping force at the same piston speed is lower than that in the low-frequency and slightly low-speed range x1, becoming a softer characteristic.

[0142] {In the extension stroke, the piston frequency is higher than the above low frequency and the piston speed is higher than the third predetermined value v3 in the high-frequency low-medium-high speed region x5}

[0143] In the high-frequency low-medium-high speed region x5, similar to the high-frequency micro-low speed region x4, the oil L from the upper chamber 19 flows to the upper chamber 19 via the fixed orifice 235, and the valve 192 of the frequency sensing mechanism 241 moves and deforms toward the bottom surface side of the annular recess 125. In the high-frequency low-medium-high speed region x5, the oil L introduced into the back pressure chamber 184 is small, and therefore, the pressure rise in the back pressure chamber 184 is suppressed by the deformation of the valve 192. Therefore, the force applied from the back pressure chamber 184 to the first damping valve 72 of the first valve mechanism 41 becomes smaller, and the first damping valve 72 is easy to open. As a result, 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 to the lower chamber 20. That is, the oil L from the upper chamber 19 flows to the lower chamber 20 via the first passage 201. As a result, in the high-frequency low-medium-high speed region x5, the rate of increase of the damping force relative to the increase of the piston speed is lower than that in the high-frequency slightly low-speed region x4. In addition, in the high-frequency low-medium-high speed region x5, the damping force at the same piston speed is lower than that in the low-frequency low-speed region x2 and the low-frequency medium-high speed region x3, and a softer characteristic is obtained. In the high-frequency low-medium-high speed region x5, since the pressure rise in the back pressure chamber 184 is suppressed, the second valve mechanism 205 maintains the closed valve state.

[0144] {In the shortened stroke, the piston speed is in a slightly low speed region y1 which is slower than the fourth predetermined value v4}

[0145] In the slightly low speed range y1, the first valve mechanism 42 and the check valve 191 are not opened. In addition, the oil L from the lower chamber 20 flows to the upper chamber via the fixed orifice 235. As a result, in the slightly low speed range y1, a damping force of an orifice characteristic (damping force is approximately proportional to the square of the piston speed) is generated. Therefore, in the slightly low speed range y1, the increase rate of the damping force relative to the increase of the piston speed is relatively high.

[0146] {In the low speed region y2 where the piston speed is greater than or equal to the fourth predetermined value v4 and slower than the fifth predetermined value v5 during the shortening stroke}

[0147] In the low speed range y2, as in the slightly low speed range y1, the oil L from the lower chamber 20 flows to the upper chamber 19 via the fixed orifice 235. In the low speed range y2, in addition to this, the oil L from the lower chamber 20 is introduced from the lower chamber communication passage 211 to the variable chamber 183, is introduced to the pilot chamber 95 by opening the check valve 191, and flows to the upper chamber 19 via the introduction orifice 142 of the disk 70 and the piston side passage 43. In the low speed range y2, the rate of increase of the damping force relative to the increase in the piston speed is lower than that in the slightly 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 secondary back pressure chamber 182, and the communicating orifice 166 suppresses the pressure rise in the primary back pressure chamber 181.

[0148] {In the middle and high speed region y3 where the piston speed is higher than the fifth prescribed value v5 during the shortening stroke}

[0149] In the middle and high speed range y3, similarly 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 opens the check valve 191 from the lower chamber communication passage 211 to flow to the upper chamber 19 via the pilot chamber 95, the introduction orifice 142, and the piston side passage 43. In the middle and high speed range y3, in addition to this, the oil L from the lower chamber 20 also flows to the upper chamber 19 via the piston side passage 44, opens the first damping valve 231 of the first valve mechanism 42. As a result, in the middle and high speed range y3, the rate of increase of the damping force relative to the increase of the piston speed is lower than that in the low speed range y2. At this time, the valve 192 of the opened check valve 191 also narrows the passage in the variable orifice 193, suppressing the pressure rise in the secondary back pressure chamber 182, and the communicating orifice 166 suppresses the pressure rise in the primary back pressure chamber 181.

[0150] 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, when the stroke is shortened, the first damping valve 72 on the extension side receives the pressure of the lower chamber 20.

[0151] When the pressure in the lower chamber 20 rises and reaches a predetermined pressure during the shortening stroke, the valve 192 of the check valve 191 provided in the pilot housing 81 opens to introduce pressure into the back pressure chamber 184. As a result, the valve closing force due to the back pressure acts on the first damping valve 72, and exceeds the valve opening force due to the pressure in the lower chamber 20 acting on the outer peripheral side of the first damping valve 72, thereby preventing the first damping valve 72 from opening during the shortening stroke.

[0152] Furthermore, during the shortening stroke, the shock absorber 1 has a characteristic that also combines the damping force characteristics of the damping valve mechanism 257 .

[0153] The above-mentioned patent document 1 discloses a buffer having a damping force generating mechanism with variable damping force at an induced frequency. In the buffer, it is required that the damping force generating mechanism works smoothly. For example, in the buffer described in patent document 1, a free valve is provided that functions as a one-way valve when the stroke is shortened and functions as a back pressure introduction valve when the stroke is extended. In this case, if the one-way valve is opened when the stroke is shortened so that the back pressure chamber becomes high pressure, there is the possibility that when the one-way valve is closed when the stroke is reversed from shortening the stroke to extending the stroke, the higher back pressure in the back pressure chamber will hinder the smooth opening of the damping force generating mechanism on the extension side, and the damping force will become higher. As a result, in a situation where a softer damping force is generated when the stroke is reversed from shortening the stroke to extending the stroke, it becomes difficult to generate a softer damping force.

[0154] The shock absorber 1 of the first embodiment includes a first passage 201 for allowing oil L as a working fluid to flow out from one upper chamber 19 in the cylinder 2 by the movement of the piston 18, and a second passage 202 provided in parallel with the first passage 201. In addition, the shock absorber 1 includes a first valve mechanism 41 provided in the first passage 201, which functions when the upper chamber 19 is in an extension stroke of the upstream pressure to adjust the damping force by the pressure of the primary back pressure chamber 181, and a frequency sensing mechanism 241 provided in the second passage 202, which functions when the upper chamber 19 is in the upstream pressure and changes the volume by the movement of the valve 192. In addition, the shock absorber 1 includes a check valve 191 provided in the second passage 202, which functions when the lower chamber 20 is in the upstream pressure to allow the oil L to flow. In addition, the shock absorber 1 includes a variable orifice 193 provided downstream of the check valve 191, and the variable orifice 193 functions when the lower chamber 20 is in the contraction stroke of the upstream pressure to control the flow of the oil L to the primary back pressure chamber 181. Thus, during the shortening stroke, even if the check valve 191 is opened, the flow of the oil L into the main back pressure chamber 181 can be suppressed by the variable orifice 193, and the main back pressure chamber 181 can be suppressed from becoming high pressure. Thus, it is possible to suppress the back pressure of the main back pressure chamber 181 from hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the shortening stroke to the extending stroke. Therefore, the damping force generating mechanism 33 including the first valve mechanism 41 can be operated smoothly. As a result, in a condition where a soft damping force is generated when the stroke is reversed from the shortening stroke to the extending stroke, a soft damping force can be generated well.

[0155] In the shock absorber 1, since the valve 192 also serves as the check valve 191, the number of components of the damping force generating mechanism 33 can be reduced and the shock absorber 1 can be made smaller.

[0156] In addition, in the shock absorber 1, a secondary back pressure chamber 182 is provided between the variable orifice 193 and the primary back pressure chamber 181. Therefore, in the shortening stroke, even if the check valve 191 is opened, the oil L flows from the variable orifice 193 to the secondary back pressure chamber 182, and the oil L flows from the secondary back pressure chamber 182 to the primary back pressure chamber 181. Thus, the flow of the oil L to the primary back pressure chamber 181 can be further suppressed, and the primary back pressure chamber 181 can be further suppressed from becoming a high pressure. As a result, it is possible to further suppress the back pressure of the primary back pressure chamber 181 from obstructing the smooth opening of the first valve mechanism 41 when the stroke is reversed from the shortening stroke to the extending stroke. Therefore, the damping force generating mechanism 33 including the first valve mechanism 41 can be made to operate more smoothly.

[0157] In addition, in the shock absorber 1, the secondary back pressure chamber 182 is connected to the main back pressure chamber 181 via the communication orifice 166. Therefore, in the shortening stroke, even if the check valve 191 is opened, the flow of the oil L to the secondary back pressure chamber 182 can be suppressed by the variable orifice 193, and the flow of the oil L from the secondary back pressure chamber 182 to the main back pressure chamber 181 can be suppressed by the communication orifice 166. Thus, the main back pressure chamber 181 can be further suppressed from becoming a high pressure. As a result, the back pressure of the main back pressure chamber 181 can be further suppressed from hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the shortening stroke to the extending stroke. Therefore, the damping force generating mechanism 33 including the first valve mechanism 41 can be made to operate more smoothly.

[0158] The damping force generating mechanism 33 of the first embodiment includes a pilot housing 81, a valve 192, and a limiting disk 78. The pilot housing 81 is a bottomed cylindrical shape, and forms a back pressure chamber 184 for generating a force in the valve closing direction in the first damping valve 72 disposed on the side of the opening 103. The valve 192 is provided at the bottom 101 of the pilot housing 81, and divides the variable chamber 183 on the side opposite to the back pressure chamber 184, and cuts off the flow of the oil L from the back pressure chamber 184 to the variable chamber 183. The limiting disk 78 abuts against the outer peripheral side of the valve 192, and limits the opening of the valve 192. In addition, the valve 192 includes a variable orifice 193 that limits the flow of the oil L from the variable chamber 183 to the back pressure chamber 184. Therefore, even if the valve 192 is opened, the flow of the oil L from the variable chamber 183 to the back pressure chamber 184 can be limited by the variable orifice 193, and the back pressure chamber 184 can be prevented from becoming a high pressure. This can prevent the back pressure of the back pressure chamber 184 from hindering smooth valve opening of the first valve mechanism 41 during stroke reversal. Therefore, the damping force generating mechanism 33 can operate smoothly.

[0159] The shock absorber 1 and the damping force generating mechanism 33 of the first embodiment can be modified as in the following Modifications 1 and 2.

[0160] <Variation 1>

[0161] In the shock absorber 1 and the damping force generating mechanism 33 of the first embodiment, the limiting disk 78 is a structure in which the disk 162 is welded to the disk 161 and integrated therewith, but the disk 162 may be integrated with the outer peripheral portion of the disk 91 of the valve 192 on the opposite side to the disk 92 by welding instead of welding the disk 162 to the disk 161. In this case, the disk 161 (limiting member) abuts against the disk 162 integrated with the disk 91, and the valve 192 including the disk 162 is pressed against the outer seat portion 114 of the pilot housing 81. That is, in this case, the disk 161 abuts against the outer peripheral side of the valve 192 including the disk 162, and the valve opening of the valve 192 is restricted.

[0162] <Variation 2>

[0163] The disk 162 is not welded to any of the disk 161 and the disk 91, but the disk 162 is positioned in the radial direction by the cylindrical portion 102 of the pilot housing 81. In this case, the disk 162 (the limiting member) abuts against the disk 91 by clamping the disk 162 in the axial direction, and the valve 192 is pressed against the outer seat portion 114 of the pilot housing 81. That is, in this case, the disk 162 abuts against the outer peripheral side of the valve 192 to limit the opening of the valve 192.

[0164] [Second embodiment]

[0165] Then, mainly based on Figure 7 The second embodiment will be described with the focus on the parts that are different from the first embodiment. In addition, the parts that are common to the first embodiment are represented by the same names and the same reference numerals.

[0166] like Figure 7 As shown, the shock absorber 1A of the second embodiment has a damping force generating mechanism 33A that is partially different from the damping force generating mechanism 33, instead of the damping force generating mechanism 33. The damping force generating mechanism 33A has a limiting plate 78A that is partially different from the limiting plate 78, instead of the limiting plate 78. The limiting plate 78A has a plate 161A that is partially different from the plate 161, instead of the plate 161.

[0167] The disk 161A is provided with a slit 171A on the inner side of the through hole 165 in the radial direction of the disk 161A. The slit 171A penetrates the disk 161A in the axial direction of the disk 161A. The slit 171A is in a straight line extending in the radial direction of the disk 161A. The disk 161A is provided with a plurality of slits 171A at equal intervals in the circumferential direction of the disk 161. The slit 171A opens to the secondary back pressure chamber 182.

[0168] The damping force generating mechanism 33A includes a valve 192A (movable member) that is partially different from the valve 192 , instead of the valve 192 . The valve 192A includes a disk 91A that is partially different from the disk 91 , instead of the disk 91 .

[0169] The disc 91A does not have the cutout 171 formed on the disc 91. The outer diameter of the disc 91A is constant throughout the entire circumference, and the inner diameter of the disc 91A is also constant throughout the entire circumference. The disc 91A is a common component having the same shape as the disc 92.

[0170] The damping force generating mechanism 33A includes a one-way valve 191A that is partially different from the one-way valve 191, instead of the one-way valve 191. The one-way valve 191A is different from the one-way valve 191 in that it includes a valve 192A instead of the valve 192. The valve 192A of the one-way valve 191A operates in the same manner as the valve 192. Thus, the one-way valve 191A operates in the same manner as the one-way valve 191.

[0171] The damping force generating mechanism 33A includes a frequency sensing mechanism 241A that is partially different from the frequency sensing mechanism 241, instead of the frequency sensing mechanism 241. The frequency sensing mechanism 241A is different from the frequency sensing mechanism 241 in that it includes a valve 192A instead of the valve 192. The valve 192A of the frequency sensing mechanism 241A operates in the same manner as the valve 192. Thus, the frequency sensing mechanism 241A operates in the same manner as the frequency sensing mechanism 241.

[0172] The damping force generating mechanism 33A has a variable orifice 193A (first throttle mechanism, first throttle portion) which is partially different from the variable orifice 193, instead of the variable orifice 193. For the variable orifice 193A, when the check valve 191A is opened, the portion on the inner peripheral side of the valve 192A approaches the disk 161A of the limiting disk 78A and narrows the flow path between it and the disk 161A. The portion on the inner peripheral side of the valve 192A and the disk 161A of the limiting disk 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 communicating orifice 166. The variable orifice 193A is provided between the pilot chamber 95 and the auxiliary back pressure chamber 182, and the flow path between the pilot chamber 95 and the auxiliary back pressure chamber 182 is changed according to the deformation amount of the valve 192A. The variable orifice 193A includes the gap 171A of the disk 161A. When the disk 91A of the valve 192A contacts the disk 161A of the limiting disk 78A, the passage in the slit 171A makes the flow path cross-sectional area in the variable orifice 193A a minimum value that is not zero. That is, the slit 171A of the disk 161A performs the same function as the notch 171 of the disk 91. In this way, the valve 192A constitutes the variable orifice 193A that restricts the inflow of the oil L from the variable chamber 183 to the auxiliary back pressure chamber 182. The valve 192A also serves as the check valve 191A. The auxiliary back pressure chamber 182 is provided between the variable orifice 193A and the primary back pressure chamber 181.

[0173] The damping force generating mechanism 33A includes a second passage 202A that is partially different from the second passage 202 instead of the second passage 202. The second passage 202A is different from the second passage 202 in that it includes a variable orifice 193A instead of the variable orifice 193.

[0174] In the shock absorber 1A, when the valve 192A of the check valve 191A is unseated from the valve seat portion 113 during the shortening stroke, 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 restricting disc 78A. As a result, the flow of the oil L from the lower chamber 20 to the secondary back pressure chamber 182 via the lower chamber communication passage 211, the variable chamber 183, and the check valve 191A in the valve open state is suppressed. As a result, the pressure rise in the secondary back pressure chamber 182 is suppressed. In this way, when the lower chamber 20 is at the upstream pressure, the variable orifice 193A provided downstream of the check valve 191A functions to suppress the flow of the oil L as the working fluid to the secondary back pressure chamber 182 and the primary back pressure chamber 181.

[0175] The hydraulic circuit diagram of the structure of the damping force generating mechanism 33A described above is the same as that of the damping force generating mechanism 33 of the first embodiment. Figure 6 , the second passage 202 becomes the second passage 202A, the one-way valve 191 becomes the one-way valve 191A, the variable orifice 193 becomes the variable orifice 193A, and the frequency sensing mechanism 241 becomes the frequency sensing mechanism 241A.

[0176] The shock absorber 1A and the damping force generating mechanism 33A of the second embodiment also include the variable orifice 193A that functions in the same manner as the variable orifice 193 , and therefore exhibit the same effects as the shock absorber 1 and the damping force generating mechanism 33 of the first embodiment.

[0177] The shock absorber 1A and the damping force generating mechanism 33A of the second embodiment can be modified as in the modification examples 1 and 2 of the first embodiment. That is, the disc 162 may be integrated with the outer peripheral portion of the disc 91A of the valve 192A on the opposite side to the disc 92 by welding, instead of welding the disc 162 to the disc 161A. Alternatively, the disc 162 may be positioned in the radial direction by the cylindrical portion 102 of the pilot housing 81, and the disc 162 may be clamped in the axial direction by the disc 161 and the disc 91A, instead of welding the disc 162 to either the disc 161 or the disc 91A.

[0178] [Third embodiment]

[0179] Then, mainly based on Figure 8 to Figure 10 The third embodiment will be described with the focus on the parts that are different from the first embodiment. In addition, the parts that are common to the first embodiment are represented by the same names and the same reference numerals.

[0180] like Figure 8As shown, the shock absorber 1B of the third embodiment has a damping force generating mechanism 33B that is partially different from the damping force generating mechanism 33, instead of the damping force generating mechanism 33. The damping force generating mechanism 33B has a limiting plate 78B that is partially different from the limiting plate 78, instead of the limiting plate 78. The limiting plate 78B has a plate 161B that is partially different from the plate 161, instead of the plate 161.

[0181] The disk 161B has a through hole 165B which is partially different from the through hole 165, instead of 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 inwardly than the through hole 165. The through hole 165B opens to the secondary back pressure chamber 182. In the disk 161B, a plurality of through holes 165B are provided at equal intervals in the circumferential direction of the disk 161B. The through hole 165B, together with the cutout 155 of the disk 77, constitutes a communication port 166 similar to the first embodiment.

[0182] The damping force generating mechanism 33B includes a valve 192B (movable member) that is partially different from the valve 192 , instead of the valve 192 . The valve 192B includes a disk 91B that is partially different from the disk 91 , instead of the disk 91 .

[0183] The disc 91B does not have the cutout 171 formed on the disc 91. The outer diameter of the disc 91B is constant throughout the entire circumference, and the inner diameter of the disc 91B is also constant throughout the entire circumference. The disc 91B is a common component having the same shape as the disc 92.

[0184] The damping force generating mechanism 33B includes a one-way valve 191B that is partially different from the one-way valve 191, instead of the one-way valve 191. The one-way valve 191B is different from the one-way valve 191 in that it includes a valve 192B instead of the valve 192. The valve 192B of the one-way valve 191B operates in the same manner as the valve 192. Thus, the one-way valve 191B operates in the same manner as the one-way valve 191.

[0185] The damping force generating mechanism 33B includes a frequency sensing mechanism 241B that is partially different from the frequency sensing mechanism 241, instead of the frequency sensing mechanism 241. The frequency sensing mechanism 241B is different from the frequency sensing mechanism 241 in that it includes a valve 192B instead of the valve 192. The valve 192B of the frequency sensing mechanism 241B operates in the same manner as the valve 192. Thus, the frequency sensing mechanism 241B operates in the same manner as the frequency sensing mechanism 241.

[0186] The damping force generating mechanism 33B is not provided with the variable orifice 193. Even when the disk 91B of the valve 192B contacts the disk 161B of the restricting disk 78B, the passage in the through hole 165B of the disk 161B allows the variable chamber 183 to communicate with the pilot chamber 95 and the secondary back pressure chamber 182.

[0187] The damping force generating mechanism 33B has a pilot housing 81B which is partially different from the pilot housing 81 instead of the pilot housing 81. The pilot housing 81B has a bottom 101B which is partially different from the bottom 101 instead of the bottom 101. The bottom 101B has a bottom body 111B which is partially different from the bottom body 111 instead of the bottom body 111. Fig. 9 As shown, only one through hole 121 is provided in the bottom body portion 111B.

[0188] The bottom portion 101B has an outer seat portion 116B which is partially different from the outer seat portion 116. The outer seat portion 116B has a connecting seat portion 311B which connects the seat forming portion 133 and the seat forming portion 133, which are arranged at the middle position in the circumferential direction of the pilot housing 81B with the passage hole 121. The connecting seat portion 311B is arranged at the outer side of the passage hole 121 in the radial direction of the pilot housing 81B. Figure 8 As shown, in the axial direction of the pilot housing 81B, the front end surface of the connecting seat portion 311B on the opposite side of the bottom body portion 111B is aligned with the front end surface of the inner seat portion 115 on the opposite side of the bottom body portion 111B and the front end surface of the seat forming portion 133 on the opposite side of the bottom body portion 111B.

[0189] The connecting seat portion 311B is provided with a notch 312B penetrating the connecting seat portion 311B in the radial direction of the pilot housing 81B. The notch 312B is recessed from the front end surface of the connecting seat portion 311B on the opposite side of the bottom body portion 111B toward the bottom body portion 111B side. The notch 312B is formed in the pilot housing 81B by coining. The notch 312B and the disk 83 abutting against the outer seat portion 116B together form an orifice 313B.

[0190] like Fig. 9 As shown, the passage recess 315B is formed by the two seat components 133 arranged on both sides of the passage hole 121 in the circumferential direction of the pilot housing 81B, the portion of the inner seat 115 between these seat components 133, and the connecting seat 311B. Figure 8 As shown, the passage recess 315B is recessed from the front end surface of the protruding side of the inner seat portion 115, the front end surface of the protruding side of the seat forming portion 133, and the front end surface of the connecting seat portion 311B along the axial direction of the pilot housing 81. The bottom surface of the passage recess 315B is formed by the bottom body portion 111. The orifice 313B opens to the inside of the passage recess 315B and the lower chamber 20.

[0191] Damping force generating mechanism 33B includes lower chamber communication passage 211B which is partially different from lower chamber communication passage 211 instead of lower chamber communication passage 211. Lower chamber communication passage 211B is composed of a passage in passage recess 315B and a passage in passage hole 121. Lower chamber communication passage 211B communicates with lower chamber 20 via orifice 313B.

[0192] Damping force generating mechanism 33B has second passage 202B which is partially different from second passage 202 instead of second passage 202. Second passage 202B is different from second passage 202 in having lower chamber communication passage 211B instead of lower chamber communication passage 211, having orifice 313B, and not having variable orifice 193.

[0193] In the shock absorber 1B, during the shortening stroke, the orifice 313B of the pilot housing 81B functions to suppress the flow of the oil L from the lower chamber 20 to the lower chamber communication passage 211B and the variable chamber 183. As a result, the flow of the oil L from the lower chamber 20 to the secondary back pressure chamber 182 via the orifice 313B, the lower chamber communication passage 211B, and the check valve 191B in the open state is suppressed. As a result, the pressure rise in the secondary back pressure chamber 182 is suppressed. In this way, when the lower chamber 20 is at the upstream pressure, the orifice 313B provided upstream of the check valve 191B functions to suppress the flow of the oil L as the working fluid to the secondary back pressure chamber 182 and the primary back pressure chamber 181.

[0194] The hydraulic circuit diagram of the structure of the damping force generating mechanism 33B described above is as follows: Fig.10 That is, the one-way valve 191 is changed into the one-way valve 191B, the frequency sensing mechanism 241 is changed into the frequency sensing mechanism 241B, and the orifice 313B is provided between the lower chamber communication passage 211B and the lower chamber 20. In addition, in the damping force generating mechanism 33B, the second passage 202 is changed into the second passage 202B, and the variable orifice 193 is not provided in the second passage 202B.

[0195] In the shock absorber 1B of the third embodiment, an orifice 313B is provided upstream of the check valve 191B, which functions to control the flow of the oil L to the main back pressure chamber 181 when the lower chamber 20 is at the upstream pressure during the shortening stroke. Thus, even if the check valve 191 is opened during the shortening stroke, the flow of the oil L to the main back pressure chamber 181 can be suppressed by the orifice 313B, and the main back pressure chamber 181 can be suppressed from becoming a high pressure. Thus, it is possible to suppress the back pressure of the main back pressure chamber 181 from hindering the smooth opening of the first valve mechanism 41 when the stroke is reversed from the shortening stroke to the extension stroke. Therefore, the damping force generating mechanism 33B including the first valve mechanism 41 can be operated smoothly. As a result, in a condition where a soft damping force is generated when the stroke is reversed from the shortening stroke to the extension stroke, a soft damping force can be generated well.

[0196] In addition, in the shock absorber 1B, a secondary back pressure chamber 182 is provided between the orifice 313B and the primary back pressure chamber 181. Therefore, in the shortening stroke, even if the check valve 191 is opened, the oil L flows from the orifice 313B to the secondary back pressure chamber 182, and the oil L flows from the secondary back pressure chamber 182 to the primary back pressure chamber 181. Thus, the flow of the oil L to the primary back pressure chamber 181 can be further suppressed, and the primary back pressure chamber 181 can be further suppressed from becoming a high pressure. As a result, it is possible to further suppress the back pressure of the primary back pressure chamber 181 from obstructing the smooth opening of the first valve mechanism 41 when the stroke is reversed from the shortening stroke to the extending stroke. Therefore, the damping force generating mechanism 33B including the first valve mechanism 41 can be made to operate more smoothly.

[0197] The shock absorber 1B and the damping force generating mechanism 33B of the third embodiment can be modified as in the modification examples 1 and 2 of the first embodiment. That is, the disc 162 may be integrated with the outer peripheral portion of the disc 91B of the valve 192B on the opposite side to the disc 92 by welding instead of welding the disc 162 to the disc 161B. Alternatively, the disc 162 may be positioned in the radial direction by the cylindrical portion 102 of the pilot housing 81 instead of welding the disc 162 to any of the disc 161 and the disc 91B, and the disc 162 may be clamped in the axial direction by the disc 161 and the disc 91B.

[0198] [Other application examples of the first to third embodiments]

[0199] The structures of the first to third embodiments are all applicable to a damping force generating mechanism of a built-in control valve type.

[0200] For example, Fig.11 and Fig.12 The shock absorber 1C has a damping force generating mechanism 33C with a built-in control valve, and shows an example in which the main structure of the damping force generating mechanism 33B of the third embodiment is applied to the extension side of the damping force generating mechanism 33C. In addition, here, the same names and the same reference numerals are used for the parts common to the third embodiment.

[0201] like Fig.11 As shown, the damping force generating mechanism 33C uses the piston 18C to separate the inner tube 3 of the cylinder 2 into an upper chamber 19 and a lower chamber 20. The damping force generating mechanism 33C includes a housing 401C, a solenoid 402C covered by the housing 401C, and a piston bolt portion 403C as a shaft member. The housing 401C of the damping force generating mechanism 33C is connected to a connecting rod 404C. The connecting rod 404C passes through the rod guide 22 (see Figure 1 ) and the sealing member 23 (refer to Figure 1 ) and extends outward from cylinder 2.

[0202] A damping force generating mechanism 411C on the extension side is provided on the lower chamber 20 side of the piston 18C, and a damping force generating mechanism 412C on the contraction side is provided on the upper chamber 19 side of the piston 18C.

[0203] Reference Fig.12 The damping force generating mechanism 411C on the extension side will be described.

[0204] The oil L having passed through the piston-side passage 43C on the extension side from the upper chamber 19 passes through the introduction port 142 on the extension side of the disk 70, passes through the introduction port 416C on the extension side of the piston bolt 415C, and enters the pilot chamber 95C on the extension side.

[0205] The expansion-side pilot chamber 95C communicates with the back pressure chamber 184 for the first damping valve 72 on the expansion side via a pilot communication passage 418C provided in the piston bolt 415C and a passage provided in the passage groove 124 of the pilot housing 81B.

[0206] The pilot valve 421C provided in the piston bolt 415C receives a closing force due to the thrust of the solenoid 402C. When the opening force based on the force of the spring 422C and the pressure of the pilot chamber 95C exceeds the thrust of the solenoid 402C, the pilot valve 421C opens. When the pilot valve 421C opens, the oil L in the pilot chamber 95C passes through the introduction port 424C on the shortened side, opens the disk valve 426C provided with the introduction port 425C on the shortened side, and flows to the lower chamber 20 through the piston side passage 44C on the shortened side.

[0207] The oil L passing through the piston side passage 43C on the extension side from the upper chamber 19 passes through the introduction port 142 provided on the extension side of the disk 70, passes through the introduction port 416C provided on the extension side of the piston bolt 415C, and enters the pilot chamber 95C on the extension side. Thereafter, the oil L passing through the passage provided in the passage groove 30C of the piston bolt 415C is introduced into the auxiliary back pressure chamber 182 of the back pressure chamber 184 via the passage provided in the passage groove 124 of the pilot housing 81B, passes through the communication port 166 provided in the restriction disk 78B and the disk 77, and enters the main back pressure chamber 181 of the back pressure chamber 184.

[0208] The valve 192B provided in the secondary back pressure chamber 182 divides the variable chamber 183 and the secondary back pressure chamber 182 into which the oil L is introduced from the lower chamber 20 via the orifice 313B provided in the pilot housing 81B and the lower chamber communication passage 211B. In addition, the valve 192B constitutes a one-way valve 191B that allows only the oil L to flow from the lower chamber 20 to the back pressure chamber 184 via the orifice 313B and the lower chamber communication passage 211B. During the extension stroke, the one-way valve 191B is always 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 amount of the valve 192B becomes small, so that the internal pressure of the back pressure chamber 184 becomes low pressure. In addition, when the axial movement of the piston 18C is low frequency, the deflection amount of the valve 192B becomes large, so that the internal pressure of the back pressure chamber 184 becomes high pressure. Therefore, the valve opening pressure of the first damping valve 72 can be changed according to the frequency. The frequency can be adjusted by the introduction port 142 provided in the disk 70. In addition, the valve opening pressure of the first damping valve 72 can be adjusted by the disk rigidity of the first damping valve 72 at high frequencies, and can be adjusted by the disk rigidity of the second damping valve 84 at low frequencies. The volume compensation of the displacement volume of the valve 192B is performed by the lower chamber communication passage 211B and the port 313B provided in the pilot housing 81B.

[0209] When the oil L in the back pressure chamber 184 reaches a predetermined pressure, the oil L 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 is opened during the extension stroke, the second damping valve 84 is opened in this way, so that the back pressure chamber 184 is communicated with the lower chamber 20. Therefore, the volume compensation of the oil L by the displacement volume of the first damping valve 72 can be performed.

[0210] 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, when the stroke is shortened, the first damping valve 72 on the extension side receives the pressure of the lower chamber 20 .

[0211] When the pressure in the lower chamber 20 rises and reaches a predetermined pressure during the shortening of the stroke, the valve 192B of the check valve 191B provided in the pilot housing 81B opens to introduce pressure into the back pressure chamber 184, so that a valve closing force based on the back pressure acts on the first damping valve 72. The valve closing force exceeds the valve opening force based on the pressure in the lower chamber 20 acting on the outer peripheral side of the first damping valve 72, thereby preventing the first damping valve 72 from opening during the shortening of the stroke.

[0212] The damping force generating mechanism 412C on the shortening side will be described.

[0213] The oil L having passed through the piston-side passage 44C on the shortened side from the lower chamber 20 passes through the introduction port 425C provided on the shortened side of the disk valve 426C, and enters the passage in the passage groove 431C on the shortened side.

[0214] The passage in the passage groove 431C on the shortening side communicates with the back pressure chamber 442C for the first damping valve 441C on the shortening side via an orifice 455C of a check valve 451C provided in the pilot housing 432C.

[0215] The pilot valve 421C provided in the piston bolt 415C receives the closing force due to the thrust of the solenoid 402C. When the opening force based on the spring 422C and the pressure of the pilot chamber 95C exceeds the thrust of the solenoid 402C, the pilot valve 421C opens. When the pilot valve 421C opens, the oil L entering the passage in the passage groove 431C passes through the pilot chamber 95C on the extension side from the introduction port 424C on the contraction side, opens the disc 70 provided with the introduction port 142 on the extension side, and flows to the upper chamber 19 through the piston side passage 43C on the extension side.

[0216] A check valve 451C and an upper chamber communication passage 452C are provided inside the pilot housing 432C, which allow only the flow of oil L from the upper chamber 19 to the back pressure chamber 442C, and an orifice 455C is provided on the inner peripheral side of the check valve 451C. When the stroke is shortened, the check valve 451C is always closed to maintain the pilot pressure in the back pressure chamber 442C.

[0217] When the first damping valve 441C is opened during stroke reduction, the back pressure chamber 442C communicates with the upper chamber 19 via the orifice 455C and the passage in the passage groove 431C, so that the volume of the oil L corresponding to the displacement volume of the first damping valve 441C can be compensated.

[0218] A second damping valve 461C, an inner circumferential groove 462C, and a release communication path 463C for releasing the pressure of the back pressure chamber 442C reaching a predetermined pressure to the upper chamber 19 are provided at the bottom of the pilot housing 432C provided with the first damping valve 441C on the shortened side.

[0219] The seat of the second damping valve 461C is a special-shaped seat, which divides the release communication passage 463C and the upper chamber communication passage 452C. The amount of back pressure introduction can be adjusted by a notch 465C provided in the seat.

[0220] 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, the first damping valve 441C on the contraction side receives the pressure of the upper chamber 19 during the extension stroke.

[0221] When the pressure in the upper chamber 19 rises and reaches a predetermined pressure during the extension stroke, the check valve 451C opens to introduce pressure into the back pressure chamber 442C, so that a valve closing force based on the back pressure acts on the first damping valve 441C. This valve closing force exceeds a valve opening force based on the pressure in the upper chamber 19 acting on the outer peripheral side of the first damping valve 441C, thereby preventing the first damping valve 441C from opening during the extension stroke.

[0222] Industrial Applicability

[0223] According to the above-described embodiment of the present invention, a shock absorber and a damping force generating mechanism capable of smoothly operating the damping force generating mechanism can be provided, which has great industrial applicability.

[0224] Description of Reference Numerals

[0225] 1, 1A, 1B, 1C…buffer, 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 component), 78, 78A, 78B…restriction plate (restriction component), 81…pilot housing (force generating component), 101…bottom, 166…communication orifice (second throttling mechanism), 181…primary back pressure chamber, 182…secondary back pressure chamber, 183…variable chamber, 184…back pressure chamber, 191, 191A, 191B…check valve, 192, 192A, 192B…valve (movable component), 193, 193A…variable orifice (first throttling mechanism, first throttling part), 201…first passage, 202…second passage, 241, 241, 241B…frequency sensing mechanism, 313B…orifice (first throttling mechanism, first throttling part).

Claims

1. A buffer having: a cylinder in which a working fluid is sealed; A piston is slidably embedded in the cylinder to divide the cylinder into a first cylinder chamber and a second cylinder chamber; a first passage for allowing the working fluid to flow out of a chamber in the cylinder through the movement of the piston; a second passage, which is arranged in parallel with the first passage; a valve mechanism, which is disposed in the first passage and can adjust the damping force by using the pressure of the main back pressure chamber; a frequency sensing mechanism, which is disposed in the second passage and causes the volume to change by the movement of the movable member; a one-way valve disposed in the second passage; a first throttling mechanism, which is arranged downstream or upstream of the one-way valve and controls the flow of the working fluid into the main back-pressure chamber; The valve mechanism and the frequency sensing mechanism both function when the first cylinder chamber is at upstream pressure. The one-way valve and the first throttle mechanism both function when the second cylinder chamber is at an upstream pressure.

2. The buffer according to claim 1, wherein: The movable member also serves as the one-way valve.

3. The buffer according to claim 1 or 2, wherein: A secondary back-pressure chamber is provided between the first throttle mechanism and the primary back-pressure chamber.

4. The buffer according to claim 3, wherein: The sub-back-pressure chamber communicates with the main back-pressure chamber via a second throttle mechanism.

5. A damping force generating mechanism, comprising: The force generating member is in the shape of a bottomed cylinder and forms a back pressure chamber for generating a force in the valve closing direction in the damping force generating member arranged on the opening side; a valve disposed at the bottom of the force generating member, dividing a variable chamber on the side opposite to the back pressure chamber, and cutting off the flow of the working fluid from the back pressure chamber to the variable chamber; a limiting member abutting against an outer peripheral side of the valve to limit the opening of the valve; The valve includes a first throttle portion that restricts inflow of the working fluid from the variable chamber into the back pressure chamber.

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