Damping force generating mechanism

Abstract

The damping force generating mechanism includes: a biasing force generating member having a bottomed cylindrical shape and forming a back pressure chamber that causes a first damping force generating member disposed on an opening side to generate a biasing force in a valve closing direction; a frequency response mechanism in which a movable mechanism is movably provided in a first passage that is provided at the bottom of the biasing force generating member and connects the back pressure chamber and a first chamber, the movable mechanism having a sealing section that seals the first passage by means of an elastic member, and varying the biasing force; a second passage which is parallel to or common to the first passage and has one side capable of communicating with the back pressure chamber; and a communication mechanism which is located on the one side of the second passage and can communicate with the other side of the second passage only when the first chamber is located on the upstream side.

Description

Technical Field

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

[0002] This application claims priority based on Japanese application No. 2022-110419, filed on July 8, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] The damping force generating mechanism provided in the shock absorber includes a type in which back pressure acts on a damping force generating member in a valve closing direction (see, for example, Patent Documents 1 and 2).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: WO2018 / 163868A

[0007] Patent document 2: US10001189B2 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] It is desirable to suppress the size increase of the damping force generating mechanism.

[0010] Therefore, an object of the present invention is to provide a damping force generating mechanism capable of suppressing enlargement.

[0011] Technical solutions for solving technical problems

[0012] One scheme of the present invention comprises: a force generating component, which is a bottomed cylindrical shape and forms a back pressure chamber that causes a first damping force generating component arranged on the opening side to generate a force in a valve closing direction; a frequency response mechanism, in which a movable mechanism is movably provided in a first passage arranged at the bottom of the force generating component and connecting the back pressure chamber with the first chamber, and the movable mechanism has a sealing portion that seals the first passage by an elastic component so that the force is variable; a second passage, which is parallel to or common with the first passage and can be connected to the back pressure chamber on one side; a connecting mechanism, which is located on one side of the second passage and can be connected to the other side of the second passage only when the first chamber is on the upstream side.

[0013] Effects of the Invention

[0014] According to the above aspect, it is possible to suppress an increase in size. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a cross-sectional view showing a shock absorber including a damping force generating mechanism according to a first embodiment of the present invention.

[0016] Figure 2 It is a cross-sectional view showing the structure of the main parts including the damping force generating mechanism according to the first embodiment.

[0017] Figure 3 It is a cross-sectional view showing the structure of a main part of the damping force generating mechanism according to the first embodiment.

[0018] Figure 4 It is a cross-sectional perspective view showing the structure of the main part of the damping force generating mechanism according to the first embodiment.

[0019] Figure 5 It is a cross-sectional view showing the structure of a main part of a damping force generating mechanism according to a second embodiment of the present invention.

[0020] Figure 6 It is a plan view showing a disk of the damping force generating mechanism according to the second embodiment.

[0021] Figure 7 It is a plan view showing a disk of the damping force generating mechanism according to the second embodiment.

[0022] Figure 8 It is a cross-sectional view showing the structure of a main part of a modification of the damping force generating mechanism of the second embodiment.

[0023] Fig. 9 It is a plan view of a disk showing a modified example of the damping force generating mechanism according to the second embodiment.

[0024] Fig.10 It is a cross-sectional view showing the structure of the main parts including the damping force generating mechanism according to the third embodiment of the present invention.

[0025] Fig.11 It is a cross-sectional view showing the structure of a main part of the damping force generating mechanism according to the third embodiment.

[0026] Fig.12 It is a cross-sectional view showing the structure of a main part of a modification of the damping force generating mechanism of the third embodiment.

[0027] Fig.13 It is a cross-sectional view showing the structure of a main part of a damping force generating mechanism according to a fourth embodiment of the present invention.

[0028] Fig.14 It is a plan view showing a pilot housing of the damping force generating mechanism according to the fourth embodiment.

[0029] Fig.15 It is a cross-sectional view showing the structure of a main part of a damping force generating mechanism according to a fifth embodiment of the present invention.

[0030] Fig.16 It is a cross-sectional view showing the structure of a main part of a damping force generating mechanism according to a sixth embodiment of the present invention.

[0031] Fig.17 It is a bottom view showing a pilot housing of the damping force generating mechanism according to the sixth embodiment.

[0032] Fig.18 It is a plan view showing a disk of the damping force generating mechanism according to the sixth embodiment.

[0033] Fig.19 It is a plan view showing a disk of the damping force generating mechanism according to the sixth embodiment.

[0034] Fig. 20 It is a cross-sectional view showing the structure of a main part of a damping force generating mechanism according to a seventh embodiment of the present invention. DETAILED DESCRIPTION

[0035] [First embodiment]

[0036] The following reference Figure 1 to Figure 4 A shock absorber including the damping force generating mechanism 10 of the first embodiment will be described. Figure 1 to Figure 3 , Figure 5 , Figure 8 , Figure 10 to Figure 13 , Fig.15 , Fig.16 , Fig. 20 Set the upper side of Figure 1 to Figure 3 , Figure 5 , Figure 8 , Figure 10 to Figure 13 , Fig.15 , Fig.16 , Fig. 20 In the description, the lower side is referred to as “lower”. In addition, in each drawing, the center axis of the shock absorber 1 may be indicated by a symbol CL.

[0037] 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 an 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 a bottomed cylindrical cylinder. The inner diameter of the outer cylinder 4 is larger than the outer diameter of the inner cylinder 3. The inner cylinder 3 is 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.

[0038] The outer tube 4 has a trunk member 11 and a bottom member 12. The trunk member 11 is cylindrical. The bottom member 12 is a bottomed cylindrical shape. The bottom member 12 is fitted into the lower side of the trunk member 11 and fixed by welding. The bottom member 12 blocks the lower part of the trunk member 11. In the bottom member 12, a mounting ring 13 is fixed to the outer side opposite to the trunk member 11 in the axial direction.

[0039] The buffer 1 includes a piston 18. The piston 18 is slidably embedded in the inner tube 3 of the cylinder 2. The piston 18 divides the inner tube 3 into two chambers, an upper chamber 19 and a lower chamber 20 (first chamber). In the axial direction of the cylinder 2, the upper chamber 19 is located on the opposite side of the bottom member 12 compared with the piston 18. In the axial direction of the cylinder 2, the lower chamber 20 is located 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.

[0040] 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 body 2. The piston rod 21 connects the one end to the piston 18. The other end side of the piston rod 21 on the side opposite to the one end in the axial direction extends from the cylinder body 2 to the outside of the cylinder body 2. The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 and the piston rod 21 move integrally. The stroke in which the piston rod 21 moves in the direction in which the protrusion amount from the cylinder body 2 increases is a stretching stroke in which the full length of the buffer 1 is extended. The stroke in which the piston rod 21 moves in the direction in which the protrusion amount from the cylinder body 2 decreases is a contraction stroke in which the full length of the buffer 1 is shortened. In the stretching stroke of the buffer 1, the piston 18 moves to the upper chamber 19 side. In the contraction stroke of the buffer 1, the piston 18 moves to the lower chamber 20 side.

[0041] 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 component 23 is fitted on the outer tube 4 at the upper side than the rod guide 22. A disc 24 is fitted on the outer tube 4 at the upper side than the sealing component 23. The rod guide 22 and the sealing component 23 are both annular. The disc 24 is a circular flat plate with a constant thickness and a hole. The disc 24 abuts against a portion of the outer peripheral side of the sealing component 23. The piston rod 21 slides relative to the rod guide 22 and the sealing component 23 along their axial directions. The piston rod 21 extends from the inside of the cylinder body 2 to the outside of the cylinder body 2 closer to the sealing component 23.

[0042] The rod guide 22 restricts the piston rod 21 from moving 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 so as to be movable in the axial direction of the piston rod 21. The outer peripheral portion of the sealing component 23 is in close contact with the outer tube 4. The inner peripheral portion of the sealing component 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 component 23 relative to the sealing component 23. The sealing component 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.

[0043] The upper portion of the outer periphery of the rod guide 22 has a larger diameter than the lower portion. 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 with the bottom valve 25. The upper end portion of the outer tube 4 is tightened radially inward of the outer tube 4. The sealing member 23 is sandwiched by the tightened portion and the rod guide 22 together with the disc 24, and is fixed to the cylinder 2.

[0044] 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 body 2. The piston 18 is mounted on the mounting shaft portion 28. 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.

[0045] On the piston rod 21, a passage groove 30 is formed on the outer periphery of the mounting shaft portion 28. The passage groove 30 is formed by grooving the outer periphery of the mounting shaft portion 28 on 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. A plurality of passage grooves 30 are formed at intervals in the circumferential direction of the mounting shaft portion 28, specifically, at two locations. On 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 side opposite to the main shaft portion 27 in the axial direction of the mounting shaft portion 28 relative to the passage groove 30.

[0046] The shock absorber 1, for example, has the portion of the piston rod 21 protruding from the cylinder 2 disposed at the upper portion and connected to the vehicle body. In that case, the shock absorber 1 has the mounting ring 13 disposed on the cylinder 2 side disposed at the lower portion and connected to the wheel side of the vehicle. The shock absorber 1 may also have the cylinder 2 side connected to the vehicle body in the opposite manner. In this case, the shock absorber 1 has the piston rod 21 connected to the wheel side.

[0047] In a vehicle, the wheels vibrate relative to the vehicle body as the vehicle travels. Then, the position between the cylinder 2 and the piston rod 21 of the shock absorber 1 changes 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 formed in a manner that varies depending on the speed and amplitude of the above-mentioned vibration. The shock absorber 1 suppresses the vibration and improves the ride feeling of the vehicle.

[0048] Furthermore, in the vehicle, in addition to the vibrations caused by the wheels relative to the vehicle body, the inertial force and centrifugal force generated on the vehicle body as the vehicle travels also act between the cylinder 2 and the piston rod 21. For example, the driving direction changes due to the steering wheel operation, thereby generating centrifugal force on 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 shock absorber 1 has good characteristics with respect to the vibrations based on the force generated on the vehicle body as the vehicle travels. The shock absorber 1 provides a high driving stability in the vehicle.

[0049] The damping force generating mechanism 10 includes a piston 18. Figure 2 The structure shown.

[0050] The piston 18 includes a piston body 35 and a sliding member 36. The piston body 35 is made of metal and is annular. The piston 18 fits the piston body 35 to the mounting shaft portion 28 of the piston rod 21. The sliding member 36 is made of synthetic resin and is annular. The sliding member 36 is integrally assembled 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.

[0051] 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 on 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 on the piston body 35 at intervals in the circumferential direction of the piston body 35. On the piston body 35, the passage holes 37 and the passage holes 39 are formed alternately and evenly spaced in each place in the circumferential direction of the piston body 35.

[0052] The passage groove 38 is formed in an annular shape on the piston body 35 along 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 open the end side of the piston body 35 in the axial direction to the passage groove 38. The passage groove 40 is formed in an annular shape on the piston body 35 along 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 side opposite to the passage groove 38 in the axial direction of the piston body 35. All the passage holes 39 open the end side of the piston body 35 on the side opposite to the passage groove 38 in the axial direction to the passage groove 40. The plurality of passage holes 37 open the end of the piston body 35 on the side opposite to the passage groove 38 in the axial direction to the outside of the passage groove 40 in the radial direction of the piston body 35. The plurality of passage holes 39 open the end portion of the piston body 35 on the side opposite to the passage groove 40 in the axial direction to the outside of the passage groove 38 in the radial direction of the piston body 35. The inner side of the plurality of passage holes 37 of the piston 18 and the inner side of the passage groove 38 form a piston side passage 43. The inner side of the plurality of passage holes 39 of the piston 18 and the inner side of the passage groove 40 form a piston side passage 44.

[0053] The damping force generating mechanism 10 has a first valve mechanism 41 provided in a piston side passage 43. The first valve mechanism 41 opens and closes the piston side passage 43 and generates a damping force. The first valve mechanism 41 is arranged on the lower chamber 20 side in the axial direction of the piston 18. Thus, the piston side passage 43 becomes a passage through which the oil L flows out from the upper chamber 19 on one side toward the lower chamber 20 on the other side by the movement of the piston 18 in one direction, i.e., the upper chamber 19 side. That is, the piston side passage 43 is a passage through which the oil L flows from the upper chamber 19 toward the lower chamber 20 during the stretching stroke. The first valve mechanism 41 suppresses the flow of the oil L from the piston side passage 43 to the lower chamber 20 generated during the stretching stroke and generates a damping force.

[0054] The damping force generating mechanism 10 has a first valve mechanism 42 provided in a piston side passage 44. The first valve mechanism 42 opens and closes the piston side passage 44 and generates a damping force. The first valve mechanism 42 is arranged on the upper chamber 19 side in the axial direction of the piston 18. Thus, the piston side passage 44 becomes a passage through which the oil L flows from the lower chamber 20 toward the upper chamber 19 by the movement of the piston 18 toward the lower chamber 20 side. That is, the piston side passage 44 is a passage through which the oil L flows from the lower chamber 20 toward the upper chamber 19 during the contraction stroke. The first valve mechanism 42 suppresses the flow of the oil L from the piston side passage 44 to the upper chamber 19 generated during the contraction stroke and generates a damping force.

[0055] 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.

[0056] An inner seat portion 46 and a valve seat portion 47 are formed at the end portion of the piston body 35 on the lower chamber 20 side in the axial direction. The inner seat portion 46 is annular. The inner seat portion 46 is arranged at the inner side of the piston body 35 in the radial direction compared to the opening of the passage groove 38 on the lower chamber 20 side. The valve seat portion 47 is annular. The valve seat portion 47 is arranged at the outer side of the piston body 35 in the radial direction compared to the opening of the passage groove 38 on the lower chamber 20 side. The valve seat portion 47 constitutes a part of the first valve mechanism 41.

[0057] An inner seat portion 48 and a valve seat portion 49 are formed at the end portion of the piston body 35 on the upper chamber 19 side in the axial direction. The inner seat portion 48 is annular. The inner seat portion 48 is arranged at the inner side of the piston body 35 in the radial direction compared to the opening of the passage groove 40 on the lower chamber 20 side. The valve seat portion 49 is annular. The valve seat portion 49 is arranged at the outer side of the piston body 35 in the radial direction compared to the opening of the passage groove 40 on the upper chamber 19 side. The valve seat portion 49 constitutes a part of the first valve mechanism 42.

[0058] The damping force generating mechanism 10 is on the side of the inner seat portion 46 in the axial direction of the piston 18, and has a disc 50, a first damping valve 52 (a first damping force generating component), a disc 53, a disc 54, multiple (specifically 6) discs 55, a disc 56, an opening and closing disc 57, a pilot housing 58 (a force generating component), a second damping valve 60 composed of multiple (specifically 6) discs 59, a disc 61, and an annular component 62 in order from the side of the inner seat portion 46 in the axial direction of the piston 18.

[0059] The disks 50, 53 to 56, 59, 61, the opening and closing disk 57, the pilot housing 58, and the annular member 62 are all made of metal. The disks 50, 53 to 56, 59, 61, the opening and closing disk 57, and the annular member 62 are all circular flat plates with holes of a constant thickness. The disks 50, 53 to 56, 59, 61, and the opening and closing disk 57 are formed by stamping. The first damping valve 52 and the pilot housing 58 are both annular. The disks 50, 53 to 56, 59, 61, the opening and closing disk 57, the first damping valve 52, the pilot housing 58, and the annular member 62 are all fitted with the mounting shaft portion 28 of the piston rod 21 on the inner side.

[0060] Also like Figure 3 As shown, the pilot housing 58 is in the shape of a bottomed cylinder. The pilot housing 58 is integrally formed without any seams by sintering. The pilot housing 58 has a bottom 65 and a cylindrical portion 66.

[0061] The bottom 65 is in the shape of a perforated circular plate, and the mounting shaft portion 28 of the piston rod 21 is fitted in its inner circumference. The cylindrical portion 66 is cylindrical, and extends from the outer circumference of the bottom 65 to one side along the axial direction of the bottom 65. The pilot housing 58 has an opening 67 on the axial side of the cylindrical portion 66 opposite to the bottom 65. In other words, the pilot housing 58 is a bottomed cylindrical shape having an opening 67 at one end in the axial direction.

[0062] The bottom portion 65 includes a bottom body portion 71 , an inner seat portion 74 , a valve seat portion 75 , an outer seat portion 76 , an inner seat portion 77 , and an outer seat portion 78 .

[0063] The bottom body 71 is a circular plate with a hole, and the mounting shaft 28 of the piston rod 21 is fitted on its inner circumference. A sealing groove 68 is formed on the bottom body 71 on the side of the cylindrical portion 66 in the axial direction. The sealing groove 68 is annular and is formed on the inner side of the cylindrical portion 66 in the radial direction of the bottom body 71. The sealing groove 68 is recessed from the cylindrical portion 66 side in the axial direction of the bottom body 71 to the direction opposite to the cylindrical portion 66 in the axial direction of the bottom 65.

[0064] The inner seat portion 74 is formed on the inner circumference of the bottom body portion 71. The inner seat portion 74 is annular and protrudes from the bottom body portion 71 to the same side as the cylindrical portion 66 in the axial direction of the bottom body portion 71.

[0065] The valve seat portion 75 is formed on the outer side of the bottom body portion 71 in the radial direction relative to the inner seat portion 74. The valve seat portion 72 is annular. The valve seat portion 75 protrudes from the bottom body portion 71 to the same side as the inner seat portion 74 in the axial direction of the bottom body portion 71. The height of the valve seat portion 75 in the axial direction of the pilot housing 58 is equal to that of the inner seat portion 74.

[0066] The outer seat portion 76 is formed on the outer side of the bottom body portion 71 in the radial direction of the valve seat portion 75 and on the inner side of the sealing groove 68. The outer seat portion 76 is annular. The outer seat portion 76 protrudes from the bottom body portion 71 to the same side as the inner seat portion 74 and the valve seat portion 75 in the axial direction of the bottom body portion 71. The height of the outer seat portion 76 from the bottom body portion 71 in the axial direction of the pilot housing 58 is higher than the valve seat portion 75.

[0067] A passage groove 79 is formed at the outer seat portion 76 at the front end in the axial direction thereof and penetrates the outer seat portion 76 in the radial direction. A plurality of passage grooves 79 are formed at equal intervals in the outer seat portion 76 in the circumferential direction of the outer seat portion 76 .

[0068] An inner passage hole 80 is formed in the bottom body portion 71. The inner passage hole 80 penetrates the bottom body portion 71 in the axial direction of the bottom body portion 71. Figure 4 As shown, a plurality of (specifically, six) inner passage holes 80 are provided at equal intervals along the circumferential direction of the pilot housing 58. Figure 3 As shown, a plurality of inner passage holes 80 open between the inner seat portion 74 and the valve seat portion 75 in the radial direction of the bottom body portion 71 .

[0069] On the pilot housing 58, as Figure 2 As shown in FIG. 1 , outer passage holes 83 and 84 are formed on the bottom surface of the sealing groove 68. The outer passage holes 83 and 84 are both located at the bottom surface of the sealing groove 68 and penetrate the bottom body portion 71 in the axial direction of the bottom body portion 71. The outer passage hole 83 is located on the inner side of the outer passage hole 84 in the radial direction of the pilot housing 58. The outer passage hole 83 is located at the inner end position of the bottom surface of the sealing groove 68 in the radial direction of the pilot housing 58. The outer passage hole 84 is located at the outer end position of the bottom surface of the sealing groove 68 in the radial direction of the pilot housing 58.

[0070] On the pilot housing 58, as Figure 4 As shown, a plurality of (specifically, three) outer passage holes 83 are provided at equal intervals along the circumferential direction of the pilot housing 58. A plurality of (specifically, three) outer passage holes 84 are provided at equal intervals along the circumferential direction of the pilot housing 58. In the pilot housing 58, the outer passage holes 83 and the outer passage holes 84 are arranged alternately and at equal intervals in the circumferential direction of the pilot housing 58. The inner passage hole 80 is arranged so that the position of the circumferential direction of the pilot housing 58 coincides with one of the outer passage holes 83 and the outer passage hole 84.

[0071] The inner seat portion 77 is formed on the inner circumference of the bottom body portion 71. The inner seat portion 77 is annular. Figure 3 As shown, the inner seat portion 74 protrudes from the inner peripheral portion of the bottom body portion 71 toward the side opposite to the inner seat portion 74 in the axial direction of the bottom body portion 71 .

[0072] The outer seat portion 78 is formed in the radially intermediate portion of the bottom body portion 71. Figure 4 As shown, the inner seat portion 77 protrudes from the bottom body portion 71 to the same side as the inner seat portion 77 in the radial direction outside the inner seat portion 77 and in the axial direction of the bottom body portion 71. The outer seat portion 78 is a non-circular petal-shaped special-shaped seat. The outer seat portion 78 has a plurality of (specifically, six) seat constituting portions 91. These seat constituting portions 91 are of the same shape and are arranged at equal intervals along the circumferential direction of the pilot housing 58. The inner seat portion 77 is in the shape of an annulus centered on the central axis of the pilot housing 58. The plurality of seat constituting portions 91 extend radially from the inner seat portion 77. The plurality of seat constituting portions 91 are located at the same position as the front end surface of the side opposite to the bottom body portion 71 in the axial direction of the pilot housing 58 and the front end surface of the inner seat portion 77 on the side opposite to the bottom body portion 71.

[0073] A passage recess 92 is formed inside each seat forming portion 91. The passage recess 92 is formed by surrounding a portion of the inner seat portion 77 and the seat forming portion 91. The passage recess 92 is recessed along the axial direction of the pilot housing 58 from the front end surface on the protruding side of the inner seat portion 77 and the front end surface on the protruding side of the seat forming portion 91. The bottom surface of the passage recess 92 is formed by the bottom body portion 71. The passage recess 92 is formed inside all the seat forming portions 91.

[0074] The inner passage hole 80 and the outer passage holes 83, 84 are provided between the seat forming parts 91 and the seat forming parts 91 adjacent to each other in the circumferential direction of the pilot housing 58. Therefore, the inner passage hole 80 and the outer passage holes 83, 84 are provided outside the outer seat part 78. The inner passage hole 80 and the outer passage holes 83, 84 do not open in the passage recess 92.

[0075] A passage groove 95 is formed on the inner seat portion 77 and passes through the inner seat portion 77 in the radial direction of the inner seat portion 77. The passage groove 95 is arranged at a position inside each of the plurality of seat forming parts 91 in the circumferential direction of the bottom body portion 71. The passage in the passage groove 95 opens into the passage recess 92. Figure 2 The passages in the passage groove 30 of the piston rod 21 are shown to be connected.

[0076] The damping force generating mechanism 10 has a partitioning member 111 (movable mechanism) in the sealing groove 68. The partitioning member 111 is annular in shape as a whole, and is an O-ring having a circular cross-section on a plane including the central axis of the ring. The partitioning member 111 is fitted into the sealing groove 68 of the pilot housing 58. The partitioning member 111 is made of an elastic material having sealing properties, specifically, rubber. Figure 3 As shown, the partition member 111 seals the gap between the partition member 111 and the radial inner wall of the sealing groove 68 by pressing the sealing portion 112 located on the inner periphery thereof against the radial inner wall of the sealing groove 68. The partition member 111 seals the gap between the partition member 111 and the radial outer wall of the sealing groove 68 by pressing the sealing portion 113 located on the outer periphery thereof against the radial outer wall of the sealing groove 68.

[0077] Figure 2 The illustrated disk 50 has an outer diameter that is larger than the outer diameter of the inner seat portion 46 of the piston 18 and smaller than the inner diameter of the valve seat portion 47. A notch 121 is formed on the disk 50. The notch 121 extends radially outward from the inner peripheral edge of the disk 50 that is engaged with the mounting shaft portion 28. The passage in the notch 121 is always connected to the piston-side passage 43 of the piston 18 and the passage in the passage groove 30 of the piston rod 21.

[0078] The first damping valve 52 is composed of a disk 131 and a sealing member 132 .

[0079] The disc 131 is made of metal and is a circular flat plate with a hole of a constant thickness. The disc 131 is formed by stamping. The outer diameter of the disc 131 is larger than the outer diameter of the valve seat portion 47 of the piston 18. The mounting shaft portion 28 of the piston rod 21 is fitted on the inner circumference of the disc 131. The first damping valve 52 abuts the disc 131 against the valve seat portion 47. The first damping valve 52 opens and closes the opening on the lower chamber 20 side of the piston side passage 43 formed on the piston 18 by the disc 131 leaving the valve seat portion 47 or abutting against the valve seat portion 47.

[0080] The sealing member 132 is made of an elastic material having sealing properties, specifically, rubber. The sealing member 132 is annular. The sealing member 132 is fixed to the outer peripheral side of the disc 131. The sealing member 132 is fitted with the inner peripheral surface of the opening 67 side of the cylindrical portion 66 of the pilot housing 58 in a manner that covers the entire circumference. The sealing member 132 can slide in the axial direction relative to the inner peripheral surface of the cylindrical portion 66. The sealing member 132 always seals the gap between the first damping valve 52 and the cylindrical portion 66. The pilot housing 58 is provided with the first damping valve 52 at its opening 67.

[0081] The outer diameter of the disk 53 is equal to the outer diameter of the inner seat portion 46 of the piston 18. The outer diameter of the disk 53 is smaller than the minimum inner diameter of the sealing member 132.

[0082] For example Figure 3 As shown, the outer diameter of the disk 54 is larger than the outer diameter of the disk 53 and smaller than the minimum inner diameter of the sealing member 132. A notch 141 is formed on the disk 54 from the inner peripheral edge to a position radially outward of the disk 53. The passage in the notch 141 is always connected to the passage in the passage groove 30 of the piston rod 21.

[0083] Among the plurality of (specifically, six) disks 55, the two disks 55 closest to the disk 54 in the axial direction have an outer diameter larger than the outer diameter of the disk 54. Among the six disks 55, the three disks 55 in the middle in the axial direction have an outer diameter larger than the outer diameter of the two disks 55 on the disk 54 side. Among the six disks 55, the disk 55 closest to the side opposite to the disk 54 in the axial direction has an outer diameter larger than the outer diameter of the three disks 55 in the middle. The outer diameter of the six disks 55 as a whole increases as they are farther away from the disk 54 in the axial direction.

[0084] The disk 56 has an outer diameter equal to that of the disk 53 .

[0085] The outer diameter of the opening and closing disc 57 is larger than the outer diameter of the valve seat portion 75 of the pilot housing 58 and smaller than the inner diameter of the outer seat portion 76. The opening and closing disc 57 can abut against the inner seat portion 74 and the valve seat portion 75 of the pilot housing 58. The opening and closing disc 57 blocks the passages in the plurality of inner passage holes 80 by seating on the valve seat portion 75. The opening and closing disc 57 opens the passages in the plurality of inner passage holes 80 by leaving the valve seat portion 75.

[0086] A notch 151 is formed on the opening and closing disk 57 from the inner peripheral edge portion fitted with the mounting shaft portion 28 to a position having a larger diameter than the outer diameter of the disk 56 and a smaller diameter than the outer diameter of the inner seat portion 74. The passage in the notch 151 is always connected to the passage in the passage groove 30 of the piston rod 21.

[0087] The sealing portions 112 and 113 of the partition member 111 are simultaneously pressed against the radially inner and radially outer wall surfaces of the sealing groove 68. As a result, the portion surrounded by the pilot housing 58, the first damping valve 52, the disks 53 to 56, the opening and closing disk 57, and the partition member 111 becomes the back pressure chamber 171. The back pressure chamber 171 is always connected to the passage in the passage groove 30 of the piston rod 21 via the passage in the notches 141 and 151.

[0088] Furthermore, the bottom surface of the sealing groove 68 and the partitioning member 111 form a variable chamber 172. Figure 2 As shown, the variable chamber 172 is always in communication with the lower chamber 20 via passages in the outer passage hole 83 and the outer passage hole 84 .

[0089] The bottomed cylindrical pilot housing 58 has a back pressure chamber 171 formed therein by the first damping valve 52, the disks 53 to 56, the opening and closing disk 57, and the partition member 111. The partition member 111 is provided in the pilot housing 58 to partition the pilot housing 58 into the back pressure chamber 171 and the variable chamber 172.

[0090] The disc 131 of the first damping valve 52 can be seated on the valve seat portion 47 of the piston 18. The first damping valve 52 is provided in the piston side passage 43 formed on the piston 18, and suppresses the flow of the oil L generated by the sliding of the piston 18 to the extension side and generates a damping force. The first damping valve 52 and the valve seat portion 47 of the piston 18 constitute the first valve mechanism 41. The first damping valve 52 is opened by the disc 131 of the first damping valve 52 being separated from the valve seat portion 47. Then, the first damping valve 52 allows the oil L from the piston side passage 43 to flow to the lower chamber 20 through the valve seat portion 47. The piston side passage 43 is a passage on the extension side through which the oil L in the upper chamber 19 flows due to the movement of the piston 18 to the upper chamber 19 side. The piston side passage 43 is a passage on the extension side through which the oil L as the working fluid flows from the upper chamber 19 on one side to the lower chamber 20 on the other side during the extension stroke. The first valve mechanism 41 on the extension side, which is composed of the valve seat portion 47 and the first damping valve 52, is provided in the piston side passage 43. The first damping valve 52 is used to open and close the piston side passage 43 to suppress the flow of the oil L, thereby generating a damping force. The lower chamber 20 is located on the downstream side of the first damping valve 52 in the flow direction of the oil L during the extension stroke.

[0091] In the first valve mechanism 41 on the extension side, a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to communicate even when they are in abutment is not formed in the valve seat portion 47 and the first damping valve 52 that abuts against the valve seat portion 47. In other words, a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to always communicate is not formed in the first valve mechanism 41. The piston side passage 43 becomes a passage on the upstream side of the first damping valve 52 in the flow direction of the oil L in the extension stroke.

[0092] The passage in the cutout 121 of the disk 50, the passage in the passage groove 30 of the piston rod 21, the passage in the cutout 141 of the disk 54, and the passage in the cutout 151 of the opening and closing disk 57 constitute a back pressure chamber introduction passage 176 that branches and extends from the piston side passage 43. The back pressure chamber introduction passage 176 connects the upper chamber 19 and the back pressure chamber 171 via a portion of the piston side passage 43. The back pressure chamber introduction passage 176 introduces the oil L from the upper chamber 19 on the upstream side of the back pressure chamber 171 to the back pressure chamber 171 via a portion of the piston side passage 43 during the extension stroke.

[0093] The passages in the outer passage holes 83, 84 and the passage in the seal groove 68, both provided in the bottom 65 of the pilot housing 58, constitute a first passage 173 extending and connecting the back pressure chamber 171 and the lower chamber 20. A partition member 111 having sealing portions 112, 113 for sealing the first passage 173 by an elastic member is movably provided in the first passage 173.

[0094] The back pressure chamber 171 causes the internal pressure to act on the first damping valve 52 in the valve closing direction along the direction of the piston 18, that is, the disk 131 is seated on the valve seat portion 47. The pilot housing 58 is a bottomed cylindrical shape and forms the back pressure chamber 171 that generates a force in the valve closing direction for the first damping valve 52 arranged on the opening portion 67 side.

[0095] The inner passage hole 80 of the pilot housing 58 is a second passage 180. The opening and closing disc 57 is provided between the second passage 180 and the back pressure chamber 171 in an openable and closable manner. The second passage 180 in the inner passage hole 80 is provided in parallel with the first passage 173 in the outer passage holes 83, 84 and in the seal groove 68. The second passage 180 is arranged on the inner peripheral side of the first passage 173 in the pilot housing 58. The opening and closing disc 57 blocks the flow of the oil L between the back pressure chamber 171, the second passage 180 and the lower chamber 20 in a state of contact with the valve seat portion 75 of the pilot housing 58. In addition, the opening and closing disc 57 allows the flow of the oil L between the back pressure chamber 171, the second passage 180 and the lower chamber 20 in a state of separation from the valve seat portion 75.

[0096] Here, the opening and closing disc 57 allows the flow of the oil L from the lower chamber 20 and the second passage 180 to the back pressure chamber 171 via the second passage 180 when the pressure on the second passage 180 and the lower chamber 20 side becomes higher than the pressure on the back pressure chamber 171 side by a predetermined value or more. The opening and closing disc 57 restricts the flow of the oil L from the back pressure chamber 171 to the lower chamber 20 via the second passage 180 when the pressure on the back pressure chamber 171 side is higher than the pressure on the second passage 180 and the lower chamber 20 side.

[0097] The opening and closing disc 57 and the valve seat portion 75 of the pilot housing 58 constitute a communication mechanism 181. One side of the second passage 180 can communicate with the back pressure chamber 171. The communication mechanism 181 is located on the one side of the second passage 180, and can communicate with the other side of the second passage 180, that is, the lower chamber 20 side, only when the lower chamber 20 is on the upstream side. In other words, the communication mechanism 181 cannot communicate with the other side of the second passage 180, that is, the lower chamber 20 side, when the lower chamber 20 is on the downstream side. The communication mechanism 181 restricts the flow of the oil L in one direction from the back pressure chamber 171 side to the lower chamber 20 side between the back pressure chamber 171 and the lower chamber 20. On the other hand, the communication mechanism 181 allows the flow of the oil L in the other direction from the lower chamber 20 side to the back pressure chamber 171 side. The communication mechanism 181 is a one-way valve, and the opening and closing disc 57 is a valve member of the communication mechanism 181.

[0098] The communication mechanism 181 restricts the flow of the oil L from the upper chamber 19, a portion of the piston side passage 43, the back pressure chamber introduction passage 176, and the back pressure chamber 171 to the second passage 180 and the lower chamber 20. The communication mechanism 181 allows the flow of the oil L from the lower chamber 20 and the second passage 180 to the back pressure chamber 171, the back pressure chamber introduction passage 176, a portion of the piston side passage 43, and the upper chamber 19.

[0099] The second damping valve 60 composed of the plurality of disks 59 as a whole has an outer diameter that increases as it approaches the pilot housing 58 in the axial direction. The outer diameter of the disk 59 closest to the pilot housing 58 among the plurality of disks 59 is slightly larger than the maximum outer diameter of the front end surface of the outer seat portion 78. The second damping valve 60 composed of the plurality of disks 59 can be seated on the outer seat portion 78 and can be unseated from the outer seat portion 78.

[0100] The passage in the passage groove 30 of the piston rod 21 and the pilot housing 58 Figure 4 The passages in the passage groove 95 and the passage recess 92 shown are Figure 2 The rod side passage 191 is further branched from the back pressure chamber introduction passage 176 branched from the piston side passage 43 and can communicate with the upper chamber 19 and the lower chamber 20. The outer seat portion 78 and the second damping valve 60 constitute a second valve mechanism 201 provided in the rod side passage 191 and opening and closing the rod side passage 191.

[0101] The second damping valve 60 of the second valve mechanism 201 is seated on the outer seat portion 78. The second damping valve 60 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 a portion of the piston side passage 43, a portion of the back pressure chamber introduction passage 176, and the rod side passage 191. In other words, the second valve mechanism 201 suppresses the flow of the oil L from the upper chamber 19 to the lower chamber 20 and generates a damping force. The second valve mechanism 201 is a damping force generating mechanism that is provided on the extension side of the rod side passage 191 and generates a damping force by the flow of the oil L.

[0102] The second valve mechanism 201 on the extension side does not form a fixed damping hole that allows the rod side passage 191 to communicate with the lower chamber 20 side even when they are in abutment with each other, either in the outer seat portion 78 or in the second damping valve 60 that abuts against the outer seat portion 78. In other words, the rod side passage 191 does not form a fixed damping hole that is always in communication with the lower chamber 20.

[0103] The outer diameter of the disk 61 is smaller than the minimum outer diameter of the second damping valve 60 .

[0104] The outer diameter of the annular member 62 is larger than the outer diameter of the disk 61 . The rigidity of the annular member 62 is higher than the rigidity of the second damping valve 60 .

[0105] The first valve mechanism 42 on the contraction side is on the inner seat portion 48 side in the axial direction of the piston 18, and has a disk 221, multiple (specifically, 4) disks 222, a disk 223, a disk 224, and an annular member 225 in order from the inner seat portion 48 side in the axial direction of the piston 18. The disks 221 to 224 and the annular member 225 are made of metal and are circular flat plates with holes of a constant thickness. The disks 221 to 224 are formed by stamping. The disks 221 to 224 and the annular member 225 are both fitted with the mounting shaft portion 28 of the piston rod 21 on the inner side.

[0106] The disk 221 has an outer diameter that is larger than the outer diameter of the inner seat portion 48 of the piston 18 and smaller than the inner diameter of the valve seat portion 49 .

[0107] The plurality of disks 222 constitute the first damping valve 231. The first damping valve 231 as a whole has an outer diameter that increases toward the disk 221 in the axial direction. The outer diameter of the disk 222 closest to the disk 221 is slightly larger than the outer diameter of the valve seat portion 49 of the piston 18.

[0108] The disk 223 has an outer diameter smaller than the outer diameter of the disk 222 having the smallest outer diameter among the plurality of disks 222 .

[0109] The disk 224 has an outer diameter larger than the outer diameter of the disk 223 .

[0110] The annular member 225 has an outer diameter that is smaller than the outer diameter of the disk 224 and larger than the outer diameter of the disk 223. The annular member 225 is thicker than the disk 222 and has high rigidity. The annular member 225 abuts against the shaft step 29 of the piston rod 21.

[0111] The first damping valve 231 composed of a plurality of disks 222 constitutes the first valve mechanism 42 together with the valve seat portion 49 of the piston 18. The first damping valve 231 is opened by being released from the valve seat portion 49. 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 valve seat portion 49. The piston side passage 44 is a passage on the contraction side through which the oil L in the lower chamber 20 flows due to the movement of the piston 18 toward the lower chamber 20. The piston side passage 44 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 contraction stroke. The first valve mechanism 42 on the contraction side composed of the valve seat portion 49 and the first damping valve 231 is provided in the piston side passage 44. The first valve mechanism 42 opens and closes the piston side passage 44 by using the first damping valve 231 and suppresses the flow of the oil L, thereby generating a damping force.

[0112] In the first valve mechanism 42 on the contraction side, a fixed damping hole that allows the lower chamber 20 and the upper chamber 19 to communicate even when they are in abutment is not formed in the valve seat portion 49 and the first damping valve 231 that abuts against the valve seat portion 49. In other words, a fixed damping hole that allows the lower chamber 20 and the upper chamber 19 to always communicate is not formed in the first valve mechanism 42 on the contraction side. The disk 224 and the annular member 225 suppress deformation of the first damping valve 231 in the opening direction beyond a predetermined value.

[0113] The pilot housing 58 and the partitioning member 111 constitute a frequency response mechanism 211 that makes the damping force variable in response to the frequency of the reciprocating motion of the piston 18 (hereinafter referred to as the piston frequency). The partitioning member 111 of the frequency response mechanism 211 moves and deforms according to the frequency of the reciprocating motion of the piston 18, so that the capacity of the back pressure chamber 171 that is always connected to the upper chamber 19 and the capacity of the variable chamber 172 that is always connected to the lower chamber 20 are changed. The frequency response mechanism 211 has the partitioning member 111 that is movably provided in the first passage 173. The frequency response mechanism 211 makes the force acting on the first damping valve 52 based on the back pressure chamber 171 variable.

[0114] During the stretching stroke, the back pressure chamber 171 side is higher than the lower chamber 20 side. Then, the partition member 111 maintains the sealed state with the sealing groove 68 due to the pressure of the back pressure chamber 171, and moves toward the bottom surface of the sealing groove 68 and abuts against the bottom surface to be compressed and deformed. As a result, the volume of the back pressure chamber 171 is expanded.

[0115] In the contraction stroke, the lower chamber 20 side is at a higher pressure than the back pressure chamber 171 side. Therefore, if the pressure difference between the lower chamber 20 side and the back pressure chamber 171 side is lower than the specified value, the partition member 111 maintains the sealing state with the sealing groove 68 due to the pressure on the lower chamber 20 side, and moves toward the disc 55 side and abuts against the disc 55 to be compressed and deformed. As a result, the volume of the variable chamber 172 is expanded. In addition, in the contraction stroke, when the lower chamber 20 side becomes a higher pressure than the back pressure chamber 171 side by a specified value or more, the connecting mechanism 181 opens the valve to allow the oil L to flow from the lower chamber 20 to the back pressure chamber 171.

[0116] On the piston rod 21, the mounting shaft portion 28 is inserted through the inner side of each, and the annular member 225, the disk 224, the disk 223, the plurality of disks 222, the disk 221, the piston 18, the disk 50, the first damping valve 52, the disk 53, the disk 54, the plurality of disks 55, the disk 56, the opening and closing disk 57, the pilot housing 58, the plurality of disks 59, the disk 61, and the annular member 62 are stacked in order on the shaft step portion 29. At that time, the pilot housing 58 makes the sealing member 132 of the first damping valve 52 fit with the cylindrical portion 66. It should be noted that in the pilot housing 58, before such assembly to the piston rod 21, the partition member 111 is pressed into the sealing groove 68.

[0117] In this state where the parts from the annular member 225 to the annular member 62 are arranged on the piston rod 21, the nut 235 is screwed onto the external thread 31 of the mounting shaft portion 28 protruding from the annular member 62. Thus, the parts from the annular member 225 to the annular member 62 overlapped as described above are clamped in the axial direction by their respective inner peripheral sides or all of them are clamped by the shaft step portion 29 of the piston rod 21 and the nut 235.

[0118] 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 comprises a bottom valve member 241, a disc valve 242, a disc valve 243 and a mounting pin 244. The bottom valve 25 is placed on the bottom member 12 at the bottom valve member 241, and is engaged with the inner tube 3 at the bottom valve member 241. The bottom valve member 241 separates the lower chamber 20 from the storage chamber 6. The disc valve 242 is provided on the lower side of the bottom valve member 241, i.e., on the storage chamber 6 side. The disc valve 243 is provided on the upper side of the bottom valve member 241, i.e., on the lower chamber 20 side. The mounting pin 244 mounts the disc valve 242 and the disc valve 243 to the bottom valve member 241.

[0119] The bottom valve member 241 is annular, and a mounting pin 244 is inserted in the center in the radial direction. A plurality of passage holes 245 and a plurality of passage holes 246 are formed in the bottom valve member 241. The plurality of passage holes 245 allow the oil L to flow between the lower chamber 20 and the storage chamber 6. The plurality of passage holes 246 are arranged on the outer side of the plurality of passage holes 245 in the radial direction of the bottom valve member 241. The plurality of passage holes 246 allow the oil L to flow between the lower chamber 20 and the storage chamber 6. The disc valve 242 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 245. On the other hand, the disc valve 242 suppresses the flow of the oil L from the storage chamber 6 to the lower chamber 20 via the passage hole 245. The disc valve 243 allows the oil L to flow from the storage chamber 6 to the lower chamber 20 via the passage hole 246. On the other hand, the disk valve 243 suppresses the flow of the oil L from the lower chamber 20 to the reservoir chamber 6 via the passage hole 246 .

[0120] The disc valve 242 forms a damping valve mechanism 247 through the bottom valve member 241. The damping valve mechanism 247 opens during the contraction stroke of the shock absorber 1 to allow the oil L to flow from the lower chamber 20 to the storage chamber 6 and generate a damping force. The disc valve 243 forms a suction valve mechanism 248 through the bottom valve member 241. The suction valve mechanism 248 opens during the extension stroke of the shock absorber 1 to allow the oil L to flow from the storage chamber 6 to the lower chamber 20. It should be noted that the suction valve mechanism 248 mainly serves to compensate for the insufficient amount of liquid generated by the extension of the piston rod 21 from the cylinder body 2 and allows the liquid to flow from the storage chamber 6 to the lower chamber 20 in a manner that substantially does not generate a damping force.

[0121] Next, the operation of the shock absorber 1 including the damping force generating mechanism 10 will be described.

[0122] {During the stretching stroke, the piston frequency is low frequency, and the piston speed is in the low frequency ultra-low speed range x1 which is slower than the first specified value v1}

[0123] In the low-frequency and ultra-low-speed range x1, the first valve mechanism 41 and the second valve mechanism 201 do not open the valves. In addition, the oil L from the upper chamber 19 flows to the back pressure chamber 171 via a portion of the piston side passage 43 and the back pressure chamber introduction passage 176. As a result, the partition member 111 of the frequency response mechanism 211 moves toward the bottom surface side of the seal groove 68 and abuts against the bottom surface to be compressed and deformed. In the low-frequency and ultra-low-speed range x1, the piston frequency is low and the piston 18 has a large stroke, so that at the beginning of the stroke, a large amount of oil L is introduced from the upper chamber 19 to the back pressure chamber 171. Therefore, the partition member 111 of the frequency response mechanism 211 moves to the bottom surface side of the seal groove 68 until it reaches the limit and deforms, and then becomes difficult to deform (high elastic force area). In addition, there is no fixed damping hole that always connects the upper chamber 19 and the lower chamber 20 in the first valve mechanism 41, 42 and the second valve mechanism 201. As a result, in the low-frequency and ultra-low-speed range x1, the rate of increase of the damping force relative to the increase in the piston speed becomes high.

[0124] {During the stretching stroke, the piston frequency is low frequency, and the piston speed is in the low frequency and low speed range x2 which is greater than the first specified value v1 and slower than the second specified value v2}

[0125] In the low-frequency and low-speed range x2, the oil L from the upper chamber 19 causes the dividing member 111 of the frequency response mechanism 211 to move and deform greatly toward the bottom surface side of the seal groove 68, as in the low-frequency and ultra-low-speed range x1. Then, it becomes difficult for the oil L from the upper chamber 19 to be introduced into the back pressure chamber 171 via the piston side passage 43 and the back pressure chamber introduction passage 176. In the low-frequency and low-speed range x2, the pressure of the back pressure chamber 171 becomes a higher pressure than that in the low-frequency and ultra-low-speed range x1. Therefore, in the low-frequency and low-speed range x2, the oil L from the upper chamber 19 flows from the piston side passage 43, the back pressure chamber introduction passage 176, and the rod side passage 191 to the lower chamber 20 by opening the second damping valve 60 of the second valve mechanism 201. As a result, in the low-frequency and low-speed range x2, the rate of increase of the damping force relative to the increase of the piston speed becomes lower than that in the low-frequency and ultra-low-speed range x1. In the low frequency and low speed range x2, the partition member 111 of the frequency response mechanism 211 moves to the limit and deforms, so the pressure in the back pressure chamber 171 becomes high pressure. Therefore, the first damping valve 52 of the first valve mechanism 41 is restricted from opening due to the large force from the back pressure chamber 171.

[0126] {During the stretching stroke, the piston frequency is low frequency, and the piston speed is in the low frequency medium and high speed range x3 above the second specified value v2}

[0127] In the low-frequency, medium-speed range x3, the oil L from the upper chamber 19 flows from a part of the piston-side passage 43, a part of the back-pressure chamber introduction passage 176, and the rod-side passage 191 to the lower chamber 20 by opening the second damping valve 60 of the second valve mechanism 201, as in the low-frequency, low-speed range x2. In the low-frequency, medium-speed range x3, the oil L flows from the rod-side passage 191 to the lower chamber 20, thereby suppressing the pressure increase of the back-pressure chamber 171 caused by the oil L introduced into the back-pressure chamber 171 via a part of the piston-side passage 43 and the back-pressure chamber introduction passage 176. In contrast, the force in the valve opening direction applied from the piston-side passage 43 to the first valve mechanism 41 increases, so the oil L from the upper chamber 19 flows to the lower chamber 20 through the piston-side passage 43 and opens the first damping valve 52 of the first valve mechanism 41. As a result, in the low-frequency, medium-speed range x3, the increase rate of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency, low-speed range x2.

[0128] {During the stretching stroke, the piston frequency is high frequency compared to the above low frequency, and the piston speed is a high frequency ultra-low speed range x4 slower than the third specified value v3}

[0129] In the high-frequency ultra-low speed range x4, the first valve mechanism 41 and the second valve mechanism 201 do not open the valves. In addition, the oil L from the upper chamber 19 flows to the back pressure chamber 171 through a part of the piston side passage 43 and the back pressure chamber introduction passage 176 as in the low-frequency ultra-low speed range x1. As a result, the partitioning component 111 of the frequency response mechanism 211 moves toward the bottom surface side of the sealing groove 68 and deforms. In the high-frequency ultra-low speed range x4, the piston frequency is high frequency and the stroke of the piston 18 is small. Therefore, the oil L introduced from the upper chamber 19 to the back pressure chamber 171 becomes less than that in the low-frequency ultra-low speed range x1. Therefore, the partitioning component 111 of the frequency response mechanism 211 is not deformed to the limit and is easy to deform (low elastic force area). As a result, the oil L introduced from the upper chamber 19 to the back pressure chamber 171 can be absorbed by the movement and deformation of the partitioning component 111. Therefore, in the high-frequency ultra-low-speed range x4, although the increase rate of the damping force relative to the increase in piston speed becomes higher, the damping force at the same piston speed becomes lower than that in the low-frequency ultra-low-speed range x1, and a soft characteristic is obtained.

[0130] {During the stretching stroke, the piston frequency is high frequency compared to the above low frequency, and the piston speed is a high frequency low, medium and high speed range x5 above the third specified value v3}

[0131] In the high-frequency, low-medium, and high-speed range x5, the oil L from the upper chamber 19 causes the partition member 111 of the frequency response mechanism 211 to move toward the bottom surface side of the seal groove 68 and deform as in the high-frequency, ultra-low-speed range x4. In the high-frequency, low-medium, and high-speed range x5, the oil L introduced into the back pressure chamber 171 is small, so the pressure rise in the back pressure chamber 171 is suppressed by the deformation of the partition member 111. Therefore, the force from the back pressure chamber 171 to the first damping valve 52 of the first valve mechanism 41 becomes smaller, and the first damping valve 52 becomes easier to open. Therefore, the oil L from the upper chamber 19 flows toward the lower chamber 20 through the piston side passage 43 and opens the first damping valve 52 of the first valve mechanism 41. As a result, in the high-frequency, low-medium, and high-speed range x5, the increase rate of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency, ultra-low-speed range x4. Furthermore, in the high frequency low, medium and high speed range x5, the damping force at the same piston speed becomes lower than that in the low frequency low speed range x2 and the low frequency medium and high speed range x3, and becomes a soft characteristic. In this high frequency low, medium and high speed range x5, the pressure rise in the back pressure chamber 171 is suppressed, so the second valve mechanism 201 maintains the closed valve state.

[0132] {During the contraction stroke, the piston frequency is low frequency, and the piston speed is in the low frequency ultra-low speed range y1 which is slower than the fourth specified value v4}

[0133] In the low-frequency and ultra-low-speed range y1, the first valve mechanism 42 and the connecting mechanism 181 do not open the valves. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172 through the passages in the outer passage holes 83 and 84 in the first passage 173. As a result, the partition member 111 of the frequency response mechanism 211 moves toward the disk 55 side and deforms. In the low-frequency and ultra-low-speed range y1, the piston frequency is low and the piston 18 has a large stroke, so that a large amount of oil L is introduced from the lower chamber 20 to the variable chamber 172 at the beginning of the stroke. Therefore, the partition member 111 of the frequency response mechanism 211 moves toward the disk 55 side to the limit and deforms, and becomes difficult to deform (high elastic force area). In addition, there is no fixed damping hole that always connects the lower chamber 20 and the upper chamber 19 in the first valve mechanism 41, 42 and the second valve mechanism 201. As a result, in the low-frequency and ultra-low-speed range y1 , the rate of increase of the damping force relative to the increase in the piston speed becomes high, resulting in a hard characteristic.

[0134] {In the contraction stroke, the piston frequency is low frequency, and the piston speed is in the low frequency and low speed range y2 which is greater than the fourth prescribed value v4 and slower than the fifth prescribed value v5}

[0135] In the low-frequency and low-speed range y2, the oil L from the lower chamber 20 moves the dividing member 111 to the disk 55 side until it is close to the limit and deforms, as in the low-frequency and ultra-low-speed range y1, and then flows from the second passage 180 to the upper chamber 19 via the back pressure chamber 171, the back pressure chamber introduction passage 176, and a part of the piston side passage 43 by opening the valve of the communication mechanism 181. As a result, in the low-frequency and low-speed range y2, the increase rate of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency and ultra-low-speed range y1.

[0136] {During the contraction stroke, the piston frequency is low frequency, and the piston speed is in the low frequency medium and high speed range y3 above the fifth specified value v5}

[0137] In the low-frequency, medium-high speed range y3, as in the low-frequency, low-speed range y2, the oil L from the lower chamber 20 flows from the second passage 180 to the upper chamber 19 via the back pressure chamber 171, the back pressure chamber introduction passage 176, and a portion of the piston side passage 43 by opening the communication mechanism 181. In the low-frequency, low-medium-high speed range y2, in addition, the oil L from the lower chamber 20 flows to the upper chamber 19 by opening the first damping valve 231 of the first valve mechanism 42 through the piston side passage 44. As a result, in the low-frequency, medium-high speed range y3, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency, low-speed range y2.

[0138] {During the contraction stroke, the piston frequency is high frequency compared to the above low frequency, and the piston speed is in the high frequency ultra-low speed range y4 which is slower than the sixth prescribed value v6}

[0139] In the high-frequency ultra-low speed range y4, the first valve mechanism 42 and the communication mechanism 181 do not open the valves. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172 through the passages in the outer passage holes 83 and 84 in the first passage 173. As a result, the partition member 111 of the frequency response mechanism 211 moves toward the disk 55 side and deforms. In the high-frequency ultra-low speed range y4, the piston frequency is high frequency and the stroke of the piston 18 is small, so the oil L introduced from the lower chamber 20 to the variable chamber 172 becomes less than that in the low-frequency ultra-low speed range y1. Therefore, the partition member 111 of the frequency response mechanism 211 is not deformed to the limit and is easy to move and deform (low elastic force area). As a result, the oil L introduced from the lower chamber 20 to the variable chamber 172 can be absorbed by the movement and deformation of the partition member 111. Therefore, in the high-frequency ultra-low speed range y4, the damping force at the same piston speed is softer than that in the low-frequency ultra-low speed range y1.

[0140] {In the contraction stroke, the piston frequency is high frequency compared to the above low frequency, and the piston speed is in the high frequency low speed range y5 which is greater than the sixth prescribed value v6 and slower than the seventh prescribed value v7}

[0141] In the high-frequency and low-speed range y5, the oil L from the lower chamber 20 flows from the first passage 173 to the upper chamber 19 via the back pressure chamber 171, the back pressure chamber introduction passage 176, and a portion of the piston side passage 43 by opening the valve of the communication mechanism 181. In the high-frequency and low-speed range y5, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency and ultra-low-speed range y4. In addition, in the high-frequency and low-speed range y5, the damping force at the same piston speed becomes lower and softer than that in the low-frequency and low-speed range y2.

[0142] {During the contraction stroke, the piston frequency is high frequency compared to the above low frequency, and the piston speed is in the high frequency medium and high speed range y6 above the seventh specified value v7}

[0143] In the high-frequency, medium-high speed range y6, as in the high-frequency, low-speed range y5, the oil L from the lower chamber 20 flows from the first passage 173 to the upper chamber 19 via the back pressure chamber 171, the back pressure chamber introduction passage 176, and a portion of the piston side passage 43 by opening the connecting mechanism 181. In the high-frequency, medium-high speed range y6, in addition, the oil L from the lower chamber 20 flows to the upper chamber 19 through the piston side passage 44 and opens the first damping valve 231 of the first valve mechanism 42. As a result, in the high-frequency, medium-high speed range y6, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency, low-speed range y5. In addition, in the high-frequency, medium-high speed range y6, the damping force at the same piston speed becomes lower and softer than that in the low-frequency, medium-high speed range y3.

[0144] It should be noted that the shock absorber 1 has characteristics that match the damping force characteristics of the damping valve mechanism 247 during the contraction stroke.

[0145] In the above-mentioned patent documents 1 and 2, a damping force generating mechanism provided in the buffer is disclosed, which causes back pressure to act on the damping force generating component in the valve closing direction. In addition, a frequency response mechanism is provided in the damping force generating mechanism of patent document 1. However, it is required to suppress the enlargement of the damping force generating mechanism.

[0146] The damping force generating mechanism 10 of the first embodiment includes a pilot housing 58, a frequency response mechanism 211, a second passage 180, and a communication mechanism 181. The pilot housing 58 is a bottomed cylindrical shape and is formed with a back pressure chamber 171 that generates a force in the valve closing direction for the first damping valve 52 disposed on the opening 67 side. The frequency response mechanism 211 is provided with a partition member 111 having sealing portions 112 and 113 that seal the first passage 173 by an elastic member in a movably manner in a first passage 173 that is provided at the bottom 65 of the pilot housing 58 and connects the back pressure chamber 171 with the lower chamber 20, so that the force in the valve closing direction for the first damping valve 52 can be varied. The second passage 180 is provided in parallel with the first passage 173, and one side can communicate with the back pressure chamber 171. The communication mechanism 181 is provided on the one side of the second passage 180, and can communicate with the other side of the second passage 180 only when the lower chamber 20 is on the upstream side.

[0147] As described above, the damping force generating mechanism 10 is provided with the first passage 173 that connects and extends the back pressure chamber 171 and the lower chamber 20 at the bottom 65 of the pilot housing 58 that forms the back pressure chamber 171. In addition, the damping force generating mechanism 10 makes the force acting on the closing direction of the first damping valve 52 variable by movably providing the partition member 111 that seals the first passage 173 with the sealing parts 112 and 113 in the first passage 173 with the frequency response mechanism 211. Therefore, although the damping force generating mechanism 10 has the frequency response mechanism 211, it is possible to suppress the size increase.

[0148] Here, in the above-mentioned contraction stroke of the damping force generating mechanism 10, the dividing member 111 of the frequency response mechanism 211 moves in the direction of shrinking the back pressure chamber 171 and undergoes elastic deformation. Therefore, when the stroke is reversed from the contraction stroke to the extension stroke, the dividing member 111 needs to recover from the elastic deformation state and move in the direction of expanding the back pressure chamber 171. As a result, when it is assumed that the connecting mechanism 181 is not provided in the damping force generating mechanism 10, it takes a long time to introduce the oil L from the upper chamber 19 to the back pressure chamber 171 through a part of the piston side passage 43 and the back pressure chamber introduction passage 176, and it takes a long time to increase the pressure of the back pressure chamber 171. Therefore, the closed valve state of the first damping valve 52, which is forced in the valve closing direction under the pressure of the back pressure chamber 171, becomes unstable. As a result, the first damping valve 52 is easily opened and the oil L flows from the piston side passage 43 to the lower chamber 20, and the increase of the damping force is delayed when the stroke is reversed from the contraction stroke to the extension stroke.

[0149] In contrast, the damping force generating mechanism 10 is provided with a connecting mechanism 181, so when the stroke is reversed from the contraction stroke to the extension stroke, the connecting mechanism 181 opens the valve, and the oil L is introduced from the lower chamber 20, which is at a higher pressure than the upper chamber 19 in the contraction stroke, to the back pressure chamber 171 via the second passage 180, so that the pressure of the back pressure chamber 171 can be quickly increased. As a result, the closed valve state of the first damping valve 52, which is urged in the valve closing direction by the pressure of the back pressure chamber 171, is stabilized. As a result, the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke can be suppressed.

[0150] Furthermore, the damping force generating mechanism 10 can suppress an increase in radial size because the second passage 180 opened and closed by the communication mechanism 181 is disposed on the inner peripheral side of the bottom 65 relative to the first passage 173 .

[0151] Furthermore, since the damping force generating mechanism 10 uses an O-ring as the partitioning member 111 having the sealing portions 112 and 113 that seal the first passage 173 by means of an elastic member, the compression deformation is large. Thus, the effect of suppressing the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke by providing the connecting mechanism 181 is high.

[0152] [Second embodiment]

[0153] Then, mainly based on Figures 5 to 9 The second embodiment will be described with the focus on the parts that are different from the first embodiment. It should be noted that the parts that are common to the first embodiment are represented by the same names and the same symbols.

[0154] like Figure 5 As shown, the shock absorber 1A including the damping force generating mechanism 10A of the second embodiment has a piston rod 21A which is partially different from the piston rod 21 instead of the piston rod 21. The piston rod 21A has a main shaft portion 27A which is partially different from the main shaft portion 27 instead of the main shaft portion 27. The main shaft portion 27A has a shaft step portion 29A which is different from the shaft step portion 29 at a point where a radial groove 251 extending in the radial direction is formed instead of the shaft step portion 29.

[0155] The piston rod 21A has a mounting shaft portion 28A which is partially different from the mounting shaft portion 28 instead of the mounting shaft portion 28. The mounting shaft portion 28A is different from the mounting shaft portion 28 in that an axial groove 252 which is connected to the radial groove 251 and extends in the axial direction is formed instead of the passage groove 30. The radial groove 251 and the axial groove 252 form a passage groove 30A which is continuously formed from the shaft step portion 29A to the outer peripheral portion of the mounting shaft portion 28A. The mounting shaft portion 28A has an external thread 31 formed on the outer peripheral portion of the end portion of the mounting shaft portion 28A which is closer to the main shaft portion 27A than the passage groove 30A in the axial direction. The radial groove 251 of the passage groove 30A formed on the shaft step portion 29 opens to the upper chamber 19.

[0156] The damping force generating mechanism 10A is provided in the shock absorber 1A instead of the damping force generating mechanism 10. The damping force generating mechanism 10A has a piston 18A instead of the piston 18. The piston 18A is slidably embedded in the inner tube 3 of the cylinder 2 in the same manner as the piston 18, and the inner tube 3 is divided into two chambers, an upper chamber 19 and a lower chamber 20.

[0157] The piston 18A has a piston body 35A and a sliding member 36A. The piston body 35A is made of metal and is seamlessly formed integrally. The piston body 35A is annular and is formed by sintering. The piston body 35A of the piston 18A is fitted with the mounting shaft portion 28A of the piston rod 21A. The sliding member 36A is made of synthetic resin and is annular. The sliding member 36A is integrally assembled on the outer peripheral surface of the piston body 35A. The piston 18A slides relative to the inner tube 3 in a state where the sliding member 36A is in contact with the inner tube 3.

[0158] The piston body 35A has a body seat 256 and a body cylindrical portion 257. The body seat 256 is a perforated circular plate. The body cylindrical portion 257 is cylindrical and extends from the outer periphery of the body seat 256 to one side along the axial direction of the body seat 256. The piston body 35A makes the mounting shaft portion 28A of the piston rod 21A fit with the inner periphery of the body seat 256.

[0159] The piston body 35A is formed with a recess 258 by the main body cylindrical portion 257 side in the axial direction of the main body seat portion 256 and the inner peripheral side of the main body cylindrical portion 257. The recess 258 is recessed along the axial direction of the piston body 35A from one axial end of the piston body 35A. Therefore, the piston 18A has a recess 258 that makes the axial dimension smaller than other ranges within a specified range on the radial inner side. The main body cylindrical portion 257 of the piston body 35A extends from the main body seat portion 256 to the lower chamber 20 side of the upper chamber 19 and the lower chamber 20. The sliding component 36A is assembled in a manner that covers the outer peripheral portions of both the main body seat portion 256 and the main body cylindrical portion 257.

[0160] The body seat portion 256 of the piston body 35A is provided with a passage hole 37A, a passage groove 38A, a passage hole 39A, and a passage groove 40A.

[0161] The passage hole 37A penetrates the main body seat portion 256 in the axial direction of the main body seat portion 256. A plurality of passage holes 37A are formed in the main body seat portion 256 at intervals in the circumferential direction of the main body seat portion 256.

[0162] The passage hole 39A penetrates the main body seat portion 256 in the axial direction of the main body seat portion 256. A plurality of passage holes 39A are formed on the main body seat portion 256 at intervals in the circumferential direction of the main body seat portion 256. On the main body seat portion 256, the passage holes 37A and the passage holes 39A are alternately formed at equal intervals in the circumferential direction of the main body seat portion 256.

[0163] The passage groove 38A is formed in an annular shape on the main body seat portion 256 along the circumferential direction of the main body seat portion 256. The passage groove 38A is formed at one end portion on the main body cylindrical portion 257 side in the axial direction of the main body seat portion 256. All the passage holes 37A open the end portion on the main body cylindrical portion 257 side in the axial direction of the main body seat portion 256 to the passage groove 38A.

[0164] The passage groove 40A is formed in an annular shape on the main body seat portion 256 along the circumferential direction of the main body seat portion 256. The passage groove 40A is formed at the other end portion of the main body seat portion 256 on the axial direction opposite to the main body cylindrical portion 257. All the passage holes 39A open the end portion of the main body seat portion 256 on the axial direction opposite to the main body cylindrical portion 257 in the passage groove 40A.

[0165] The end of the main body seat 256 on the side opposite to the passage groove 38A in the axial direction is opened to the outside of the passage groove 40A in the radial direction of the main body seat 256. The end of the main body seat 256 on the side opposite to the passage groove 40A in the axial direction is opened to the outside of the passage groove 38A in the radial direction of the main body seat 256. The inner side of the plurality of passage holes 37A of the piston 18A and the inner side of the passage groove 38A constitute the piston side passage 43A. The inner side of the plurality of passage holes 39A of the piston 18A and the inner side of the passage groove 40A constitute the piston side passage 44A.

[0166] The damping force generating mechanism 10A has a piston valve mechanism 201A provided with respect to the piston side passage 43A of the piston 18A. The piston valve mechanism 201A opens and closes the piston side passage 43A and generates a damping force. The piston valve mechanism 201A is provided on the lower chamber 20 side of the piston 18A in the axial direction of the piston 18A. The piston side passage 43A is a passage for the oil to flow out from the upper chamber 19 toward the lower chamber 20 during the movement of the piston 18A toward the upper chamber 19 side. In other words, the piston side passage 43A is a passage on the extension side for the oil to flow out from the upper chamber 19 toward the lower chamber 20 during the extension stroke of the shock absorber 1A. The piston valve mechanism 201A is a damping force generating part on the extension side that suppresses the flow of the oil in the piston side passage 43A and generates a damping force.

[0167] The damping force generating mechanism 10A has a first valve mechanism 42A provided with respect to the piston side passage 44A of the piston 18A. The first valve mechanism 42A opens and closes the piston side passage 44A and generates a damping force. The first valve mechanism 42A is provided on the upper chamber 19 side of the piston 18A in the axial direction of the piston 18A. The piston side passage 44A becomes a passage for the oil to flow out from the lower chamber 20 toward the upper chamber 19 during the movement of the piston 18A toward the lower chamber 20 side. In other words, the piston side passage 44A becomes a passage on the contraction side for the oil to flow out from the lower chamber 20 toward the upper chamber 19 during the contraction stroke of the shock absorber 1A. The first valve mechanism 42A is a damping force generating portion on the contraction side that suppresses the flow of the oil in the piston side passage 44A and generates a damping force.

[0168] An inner seat portion 46A and a valve seat portion 47A are formed at the end portion of the main body seat portion 256 on the lower chamber 20 side in the axial direction, closer to the radial inner side than the main body cylindrical portion 257. The inner seat portion 46A is annular. The valve seat portion 47A is also annular. The inner seat portion 46A is arranged at the radial inner side of the main body seat portion 256 compared to the opening of the passage groove 38A on the lower chamber 20 side. The valve seat portion 47A is arranged at the radial outer side of the main body seat portion 256 compared to the opening of the passage groove 38A on the lower chamber 20 side. The valve seat portion 47A constitutes a part of the piston valve mechanism 201A.

[0169] An inner seat portion 48A and a valve seat portion 49A are formed at the end portion of the main body seat portion 256 on the upper chamber 19 side in the axial direction, that is, the end portion of the piston body 35A on the upper chamber 19 side in the axial direction. The inner seat portion 48A is annular. The valve seat portion 49A is also annular. The inner seat portion 48A is arranged at the inner side of the main body seat portion 256 in the radial direction compared to the opening of the passage groove 40A on the upper chamber 19 side. The valve seat portion 49A is arranged at the outer side of the main body seat portion 256 in the radial direction compared to the opening of the passage groove 40A on the upper chamber 19 side. The valve seat portion 49A constitutes a part of the first valve mechanism 42A.

[0170] In the main body seat portion 256, the openings on the lower chamber 20 side in all the passage holes 39A are arranged on the side of the valve seat portion 47A opposite to the passage groove 38A in the radial direction of the main body seat portion 256. In the main body seat portion 256, the openings on the upper chamber 19 side of all the passage holes 37A are arranged on the side of the valve seat portion 49A opposite to the passage groove 40A in the radial direction of the main body seat portion 256.

[0171] The damping force generating mechanism 10A has a damping valve 261 composed of a plurality of (specifically, four) discs 260 on the lower chamber 20 side in the axial direction of the main body seat portion 256. The damping force generating mechanism 10A has a disc 262, a disc 263, a disc 264, and a disc 265 in order from the damping valve 261 side on the axial side opposite to the main body seat portion 256. The discs 260, 262 to 265 are all made of metal and formed by stamping. The discs 260, 262 to 265 are all in the shape of a flat plate with holes of a constant thickness. The discs 260, 262 to 265 are all fitted with the mounting shaft portion 28A of the piston rod 21A on the inner circumference side.

[0172] The outer diameter of the damping valve 261 as a whole decreases as it moves away from the main body seat portion 256 in the axial direction. The inner seat portion 46A and the valve seat portion 47A of the piston 18A abut against the disc 260 of the damping valve 261 that is closest to the main body seat portion 256. The damping valve 261 opens and closes the piston side passage 43A provided in the piston 18A and generates a damping force by seating on the valve seat portion 47A or leaving the valve seat portion 47A. The damping valve 261 constitutes the piston valve mechanism 201A on the tension side. The piston valve mechanism 201A does not have a fixed damping hole between the damping valve 261 and the valve seat portion 47A to always connect the piston side passage 43A with the lower chamber 20.

[0173] The outer diameter of the disk 262 is smaller than the outer diameter of the disk 260 having the smallest outer diameter among the plurality of disks 260 constituting the damping valve 261 .

[0174] The outer diameter of the disk 263 is larger than the outer diameter of the disk 262 .

[0175] The outer diameter of the disk 264 is equal to the outer diameter of the disk 263. A notch 267 is formed on the outer circumference of the disk 264. Figure 6 As shown, a plurality of (specifically, eight) cutouts 267 are arranged at equal intervals along the circumference of the disk 264 .

[0176] like Figure 5 As shown in FIG. 1 , the outer diameter of the disk 265 is equal to the outer diameters of the disks 263 and 264. A passage hole 268 is formed at the radial middle position of the disk 265. The passage hole 268 is as shown in FIG. Figure 7As shown in FIG. 2 , the circular disk 265 is in an arc shape concentric with the circular disk 265. A plurality of (specifically, three) passage holes 268 are provided on the circular disk 265 at equal intervals along the circumference of the circular disk 265. Figure 5 As shown, the inner portion of the cutout 267 and the passage hole 268 are aligned in the radial direction of the disks 264 and 265. Therefore, the cutout 267 and the passage hole 268 are communicated.

[0177] The damping force generating mechanism 10A has a first damping valve 231A composed of a plurality of (specifically, three) disks 222A on the upper chamber 19 side in the axial direction of the piston 18A. The damping force generating mechanism 10A has a disk 223A on the side of the first damping valve 231A opposite to the piston 18A in the axial direction. The damping force generating mechanism 10A has an annular member 225A on the side of the disk 223A opposite to the first damping valve 231A in the axial direction.

[0178] The disks 222A, 223A and the annular member 225A are all made of metal. The disks 222A, 223A are both flat plates with a constant thickness and are both annular. The annular member 225A is annular. The disks 222A, 223A and the annular member 225A are all fitted with the mounting shaft 28A of the piston rod 21A on the inner circumference side.

[0179] The first damping valve 231A as a whole has an outer diameter that decreases as it becomes farther away from the body seat portion 256 in the axial direction.

[0180] The outer diameter of the disk 223A is smaller than the outer diameter of the disk 222A with the smallest outer diameter among the plurality of disks 222A. The outer diameter of the annular member 225A is larger than the outer diameter of the disk 223A, and smaller than the outer diameter of the disk 222A with the smallest outer diameter among the plurality of disks 222A. The annular member 225A is thicker and more rigid than the disks 222A constituting the first damping valve 231A. The annular member 225A contacts the shaft step portion 29A of the piston rod 21A.

[0181] The valve seat portion 49A of the piston 18A abuts against the outer peripheral side of the disc 222A which is closest to the main body seat portion 256 in the axial direction of the first damping valve 231A. The first damping valve 231A opens and closes the piston side passage 44A provided in the piston 18A and generates a damping force by seating on the valve seat portion 49A or leaving the valve seat portion 49A. The first damping valve 231A blocks the opening of one side of the piston side passage 44A, i.e., the upper chamber 19 side. The first damping valve 231A constitutes the first valve mechanism 42A on the contraction side. The first valve mechanism 42A does not have a fixed damping hole between the first damping valve 231A and the valve seat portion 49A to always connect the piston side passage 44A and the upper chamber 19. The annular member 225A contacts the first damping valve 231A when the first damping valve 231A deforms in the opening direction, thereby suppressing the deformation of the first damping valve 231A above a predetermined value.

[0182] The damping force generating mechanism 10A has a pilot housing 58A (force generating member) on the axial side of the disk 265 opposite to the disk 264. The pilot housing 58A is made of metal and is seamlessly integrally formed by sintering. The pilot housing 58A is a bottomed cylindrical shape and has a bottom 65A and a cylindrical portion 66A.

[0183] The bottom 65A is a perforated disc, and the mounting shaft 28A of the piston rod 21A is fitted in its inner circumference. The cylindrical portion 66A is cylindrical, extending from the outer circumference of the bottom 65A to one side along the axial direction of the bottom 65A. The pilot housing 58A has an opening 67A on the axial side of the cylindrical portion 66A opposite to the bottom 65A.

[0184] The bottom portion 65A includes a bottom body portion 71A, an inner seat portion 74A, an intermediate seat portion 304, and a valve seat portion 75A.

[0185] The bottom body portion 71A is in the shape of a disk having a hole, and the mounting shaft portion 28A of the piston rod 21A is fitted on the inner peripheral side thereof.

[0186] The inner seat portion 74A, the intermediate seat portion 304, and the valve seat portion 75A are provided on the cylindrical portion 66A side in the axial direction of the bottom body portion 71A and on the inner side of the cylindrical portion 66A in the radial direction of the bottom body portion 71A. The inner seat portion 74A, the intermediate seat portion 304, and the valve seat portion 75A protrude from the bottom body portion 71A to the cylindrical portion 66A side in the axial direction of the bottom body portion 71A.

[0187] The inner seat portion 74A is provided on the inner peripheral side of the bottom portion 65A. The inner seat portion 74A has an annular shape.

[0188] The middle seat portion 304 is disposed at the outer side of the bottom portion 65A in the radial direction than the inner seat portion 74A. The middle seat portion 304 is annular and surrounds the inner seat portion 74A. A passage groove 311 is formed on the middle seat portion 304 and penetrates the middle seat portion 304 in the radial direction of the middle seat portion 304. A plurality of passage grooves 311 are formed on the middle seat portion 304 at equal intervals in the circumferential direction of the middle seat portion 304.

[0189] The valve seat portion 75A is provided on the outer side of the bottom portion 65A in the radial direction relative to the intermediate seat portion 304. The valve seat portion 75A has an annular shape surrounding the intermediate seat portion 304.

[0190] The bottom body portion 71A is provided with a seal groove 68A on the side opposite to the cylindrical portion 66A in the axial direction. The seal groove 68A is annular and is formed on the outer peripheral side of the bottom body portion 71A. The bottom body portion 71A has an outer passage hole 83A that penetrates from the radially outer portion of the bottom surface of the seal groove 68A along the axial direction of the bottom body portion 71A. A plurality of outer passage holes 83A are formed in the bottom body portion 71A at equal intervals in the circumferential direction. The outer passage holes 83A open between the cylindrical portion 66A and the valve seat portion 75A in the radial direction of the bottom body portion 71A.

[0191] The bottom body portion 71A has an inner passage hole 80A extending in the axial direction of the bottom body portion 71A at a position radially inward of the seal groove 68A. The bottom body portion 71A is provided with a plurality of inner passage holes 80A at equal intervals in the circumferential direction of the bottom body portion 71A. The inner passage holes 80A open between the inner seat portion 74A and the intermediate seat portion 304 in the radial direction of the bottom body portion 71A. The inner passage holes 80A are located inward of the outer passage holes 83A in the radial direction of the pilot housing 58A.

[0192] A passage groove 320 is formed in the bottom body portion 71A on the side opposite to the cylindrical portion 66A in the axial direction thereof, which allows the inner passage hole 80A to communicate with the opening side of the seal groove 68A.

[0193] The pilot housing 58A contacts the disc 265 at the end of the bottom body portion 71A on the side opposite to the cylindrical portion 66A in the axial direction. At that time, the disc 265 covers the opening of the seal groove 68A except for the radially outer portion. And, at that time, the passage hole 268 of the disc 265 communicates with the radially inner portion of the opening of the seal groove 68A.

[0194] The damping force generating mechanism 10A has a partitioning component 111A (movable mechanism) in the sealing groove 68A. The partitioning component 111A is annular as a whole, and is an O-ring whose cross section on the plane including the central axis of the annular ring is circular. The partitioning component 111A is made of an elastic material with sealing properties, specifically, rubber. The partitioning component 111A is embedded in the sealing groove 68A. The partitioning component 111A seals the gap between the wall surface of the radial inner side of the sealing groove 68A by pressing the sealing portion 112A located on its inner periphery against the wall surface of the radial inner side of the sealing groove 68A. The partitioning component 111A seals the gap between the wall surface of the radial outer side of the sealing groove 68A by pressing the sealing portion 113A located on its outer periphery against the wall surface of the radial outer side of the sealing groove 68A. The partitioning component 111A moves in the axial direction of the partitioning component 111A in the sealing groove 68A. The partitioning component 111A elastically deforms in the axial direction of the partitioning component 111A in the sealing groove 68A.

[0195] The damping force generating mechanism 10A is on the inner seat portion 74A side in the axial direction of the pilot housing 58A, and has an opening and closing disc 57A, a disc 321, a disc 322, a disc 323, a plurality of (specifically 5) discs 324, a first damping valve 52A (first damping force generating component), and a seat forming component 325 in order from the inner seat portion 74A side in the axial direction of the pilot housing 58A.

[0196] The opening and closing disc 57A, the discs 321 to 324, and the seat forming member 325 are all made of metal. The opening and closing disc 57A and the discs 321 to 324 are all circular flat plates with holes of a constant thickness, and are formed by stamping. The first damping valve 52A and the seat forming member 325 are both annular. The first damping valve 52A, the opening and closing disc 57A, the discs 321 to 324, and the seat forming member 325 are all fitted with the mounting shaft portion 28 of the piston rod 21 on the inner side.

[0197] The outer diameter of the opening and closing disc 57A is larger than the outer diameter of the valve seat portion 75A of the pilot housing 58A. The opening and closing disc 57A can abut against the inner seat portion 74A, the intermediate seat portion 304 and the valve seat portion 75A of the pilot housing 58A. The opening and closing disc 57 blocks the passages in the plurality of inner passage holes 80A by seating on the valve seat portion 75A. The opening and closing disc 57A opens the passages in the plurality of inner passage holes 80A by leaving the seat from the valve seat portion 75A. The opening and closing disc 57A has a notch 151A extending in the radial direction of the opening and closing disc 57A formed in the range of the inner seat portion 74A, starting from the inner peripheral edge portion engaged with the mounting shaft portion 28A.

[0198] The outer diameter of the disk 321 is smaller than that of the opening and closing disk 57A and smaller than that of the inner seat portion 74A of the pilot housing 58A. The disk 321 has an outer diameter that does not cover the outer end of the radial cutout 151A of the opening and closing disk 57A.

[0199] The outer diameter of the disk 322 is larger than the outer diameter of the disk 321. The disk 322 has a notch 327 formed in the outer peripheral portion.

[0200] The outer diameter of the disk 323 is smaller than the outer diameter of the disk 322 .

[0201] The outer diameter of the disk 324 is smaller than the outer diameter of the disk 323 .

[0202] The first damping valve 52A is composed of a disk 131A and a sealing member 132A.

[0203] The disk 131A is made of metal and has a circular flat plate shape with a constant thickness and a hole. The disk 131A is formed by press forming. The mounting shaft portion 28A of the piston rod 21A is fitted on the inner circumference of the disk 131A.

[0204] The sealing member 132A is made of an elastic material having sealing properties, specifically, is made of rubber. The sealing member 132A is annular. The sealing member 132A is fixed to the outer peripheral side of the disc 131A. The sealing member 132A is fitted with the inner peripheral surface of the opening portion 67A side of the cylindrical portion 66A of the pilot housing 58A in a manner that covers the entire circumference. The sealing member 132A can slide axially relative to the inner peripheral surface of the cylindrical portion 66A. The sealing member 132A always seals the gap between the first damping valve 52A and the cylindrical portion 66A. The pilot housing 58A is provided with the first damping valve 52A at its opening portion 67A.

[0205] The seat forming member 325 is made of metal and has an annular shape. The seat forming member 325 is seamlessly integrally formed by sintering. The seat forming member 325 includes a member body portion 331 , an inner seat portion 332 , and a valve seat portion 333 .

[0206] The member body portion 331 is in the shape of a perforated circular plate, and the mounting shaft portion 28A of the piston rod 21A is fitted into the inner circumference thereof.

[0207] The inner seat portion 332 protrudes from the inner peripheral edge of the component body portion 331 to one axial side of the component body portion 331. The inner seat portion 332 is annular. A passage groove 335 is formed on the inner seat portion 332 and penetrates the inner seat portion 332 in its radial direction. The passage groove 335 is connected to the passage groove 30A of the piston rod 21A.

[0208] The valve seat portion 333 protrudes from the outer peripheral side of the component body portion 331 in the axial direction of the component body portion 331. The valve seat portion 333 is annular and surrounds the inner seat portion 332. The valve seat portion 333 protrudes from the component body portion 331 in the axial direction of the component body portion 331 to the same side as the inner seat portion 332.

[0209] The seat forming member 325 is oriented such that the inner seat portion 332 and the valve seat portion 333 are located on the first damping valve 52A side in the axial direction. The nut 235 abuts against the axial side of the seat forming member 325 opposite to the first damping valve 52A.

[0210] The outer diameter of the disk 131A of the first damping valve 52A is larger than the outer diameter of the valve seat portion 333. The disk 131A of the first damping valve 52A abuts against the valve seat portion 333.

[0211] The passage in the passage groove 30A of the piston rod 21A, the passage in the passage groove 335 of the seat forming member 325, and the passage between the inner seat portion 332 of the seat forming member 325 and the valve seat portion 333 constitute the rod side passage 341. The first damping valve 52A opens and closes the rod side passage 341 by separating the disc 131A from the valve seat portion 333 and contacting the disc 131A with the valve seat portion 333.

[0212] The first damping valve 52A is provided in the rod side passage 341, and suppresses the flow of the oil L generated by the sliding of the piston 18A toward the extension side and generates a damping force. The first damping valve 52A constitutes the first valve mechanism 41A together with the valve seat portion 333 of the seat forming component 325. The first damping valve 52A is opened by the disc 131A thereof being separated from the valve seat portion 333. Thus, the first damping valve 52A allows the oil L from the rod side passage 341 to flow toward the lower chamber 20 via the valve seat portion 333. The rod side passage 341 becomes a passage on the extension side through which the oil L in the upper chamber 19 flows due to the movement of the piston 18A toward the upper chamber 19 side. The rod side passage 341 allows the oil L as the working fluid to flow out from the upper chamber 19 on one side toward the lower chamber 20 on the other side during the extension stroke. The first valve mechanism 41A on the tension side composed of the valve seat portion 333 and the first damping valve 52A is provided in the rod side passage 341 , and the first damping valve 52A opens and closes the rod side passage 341 to suppress the flow of the oil L, thereby generating a damping force.

[0213] The first valve mechanism 41A on the extension side does not form a fixed damping hole that allows the upper chamber 19 and the lower chamber 20 to communicate even if they are in abutment, either in the valve seat portion 333 or in the first damping valve 52A that abuts against the valve seat portion 333. That is, the first valve mechanism 41A on the extension side does not form a fixed damping hole that allows the upper chamber 19 and the lower chamber 20 to always communicate. The rod side passage 341 becomes a passage on the upstream side of the first damping valve 52A in the flow direction of the oil L in the extension stroke. The lower chamber 20 is on the downstream side of the first damping valve 52A in the flow direction of the oil L in the extension stroke.

[0214] The sealing portions 112A and 113A of the partition member 111A are simultaneously pressed against the radially inner and radially outer wall surfaces of the sealing groove 68A. As a result, the portion surrounded by the pilot housing 58A, the first damping valve 52A, the opening and closing disc 57A, the discs 321 to 324, and the partition member 111A becomes the back pressure chamber 171A. The back pressure chamber 171A is always connected to the passage in the passage groove 30A of the piston rod 21A via the passage in the cutout 151A of the opening and closing disc 57A.

[0215] Furthermore, the partition member 111A forms a variable chamber 172A between the partition member 111A of the sealing groove 68A and the disk 265. The variable chamber 172A is always connected to the lower chamber 20 via the passage between the outer circumference of the disk 265 and the sealing groove 68A. The variable chamber 172A is always connected to the lower chamber 20 via the passage hole 268 of the disk 265 and the passage in the cutout 267 of the disk 264.

[0216] The bottomed cylindrical pilot housing 58A has a back pressure chamber 171A formed therein by the first damping valve 52A, the opening and closing disk 57A, the disks 321 to 324, and the partition member 111A. The partition member 111A is provided in the pilot housing 58A to partition the pilot housing 58A into the back pressure chamber 171A and the variable chamber 172A.

[0217] The passage in the cutout 151A of the opening and closing disc 57A constitutes a back pressure chamber introduction passage 176A that branches from the rod side passage 341 and communicates with the back pressure chamber 171A. The back pressure chamber introduction passage 176A communicates the upper chamber 19 with the back pressure chamber 171A via the rod side passage 341. The back pressure chamber introduction passage 176A introduces the oil L from the upper chamber 19 on the upstream side of the back pressure chamber 171A to the back pressure chamber 171A via the rod side passage 341 during the extension stroke.

[0218] The passage in the outer passage hole 83A provided in the bottom 65A of the pilot housing 58A, the passage in the seal groove 68A, the passage in the passage hole 268 of the disk 265 and the notch 267 of the disk 264, and the passage between the outer peripheral portion of the disk 265 and the seal groove 68A constitute a first passage 173A extending and connecting the back pressure chamber 171A and the lower chamber 20. A partition member 111A having seal portions 112A and 113A for sealing the first passage 173A by an elastic member is movably provided in the first passage 173A.

[0219] The back pressure chamber 171A causes the internal pressure to act on the first damping valve 52A in the valve closing direction along the direction of the seat forming member 325, that is, the disk 131A is seated on the valve seat portion 333. The pilot housing 58A is a bottomed cylindrical shape and forms the back pressure chamber 171A that generates a force in the valve closing direction for the first damping valve 52A disposed on the opening portion 67A side.

[0220] The second passage 180A is formed in the plurality of inner passage holes 80A and the passage groove 320 of the pilot housing 58A. The second passage 180A is connected to the variable chamber 172A. The opening and closing disc 57A is provided between the second passage 180A and the back pressure chamber 171A in an openable and closable manner. The second passage 180A is provided in parallel with the first passage 173A. The second passage 180A is arranged on the inner peripheral side of the first passage 173A in the pilot housing 58A. The opening and closing disc 57A cuts off the flow of the oil L between the back pressure chamber 171A and the second passage 180A and the lower chamber 20 in a state of contact with the valve seat portion 75A of the pilot housing 58A. In addition, the opening and closing disc 57A allows the flow of the oil L between the back pressure chamber 171A and the second passage 180A and the lower chamber 20 in a state of separation from the valve seat portion 75A.

[0221] Here, the opening and closing disc 57A allows the flow of the oil L from the lower chamber 20 and the second passage 180A to the back pressure chamber 171A when the pressure on the second passage 180A and the lower chamber 20 side becomes higher than the pressure on the back pressure chamber 171A side by a predetermined value or more. The opening and closing disc 57A restricts the flow of the oil L from the back pressure chamber 171A to the lower chamber 20 via the second passage 180A when the pressure on the back pressure chamber 171A side is higher than the pressure on the second passage 180A and the lower chamber 20 side.

[0222] The opening and closing disc 57A and the valve seat portion 75A of the pilot housing 58A constitute a communication mechanism 181A. One side of the second passage 180A can communicate with the back pressure chamber 171A. The communication mechanism 181A is located on the one side of the second passage 180A, and can communicate with the other side of the second passage 180A, that is, the lower chamber 20 side, only when the lower chamber 20 is located on the upstream side. In other words, the communication mechanism 181A cannot communicate with the other side of the second passage 180A, that is, the lower chamber 20 side, when the lower chamber 20 is located on the downstream side. The communication mechanism 181A restricts the flow of the oil L in one direction from the back pressure chamber 171A side to the variable chamber 172A side through the second passage 180A between the back pressure chamber 171A and the variable chamber 172A. On the other hand, the communication mechanism 181A allows the flow of the oil L in the other direction from the variable chamber 172A side to the back pressure chamber 171A side through the second passage 180A. The communication mechanism 181A is a one-way valve, and the opening and closing disc 57A is a valve member of the communication mechanism 181A.

[0223] The communication mechanism 181A restricts the flow of the oil L from the upper chamber 19, a portion of the rod-side passage 341, the back-pressure chamber introduction passage 176A, and the back-pressure chamber 171A to the second passage 180A and the lower chamber 20. The communication mechanism 181A allows the flow of the oil L from the lower chamber 20 and the second passage 180A to the back-pressure chamber 171A, the back-pressure chamber introduction passage 176A, a portion of the rod-side passage 341, and the upper chamber 19.

[0224] The pilot housing 58A and the partitioning member 111A constitute a frequency response mechanism 211A that makes the damping force variable in response to the piston frequency. The partitioning member 111A of the frequency response mechanism 211A moves and deforms according to the frequency of the reciprocating motion of the piston 18A, so that the capacity of the back pressure chamber 171A that is always connected to the upper chamber 19 and the capacity of the variable chamber 172A that is always connected to the lower chamber 20 are changed. The frequency response mechanism 211A has the partitioning member 111A movably provided in the first passage 173A. The frequency response mechanism 211A makes the force acting on the first damping valve 52A based on the back pressure chamber 171A variable.

[0225] During the extension stroke, the back pressure chamber 171A side is higher than the lower chamber 20 side. Then, the partition member 111A maintains the sealing state with the seal groove 68A due to the pressure of the back pressure chamber 171A, and moves toward the disk 265 side and abuts against the disk 265 to be compressed and deformed. As a result, the volume of the back pressure chamber 171A is expanded.

[0226] During the contraction stroke, the lower chamber 20 side is at a higher pressure than the back pressure chamber 171A side. Therefore, if the pressure difference between the lower chamber 20 side and the back pressure chamber 171A side is lower than the specified value, the dividing member 111A is subjected to the pressure on the lower chamber 20 side, and maintains the sealing state between the sealing groove 68A, and moves toward the bottom surface of the sealing groove 68A and abuts against the bottom surface to be compressed and deformed. As a result, the volume of the variable chamber 172A is expanded. Furthermore, during the contraction stroke, when the lower chamber 20 side becomes a higher pressure than the back pressure chamber 171A side by a specified value, the connecting mechanism 181A opens the valve to allow the oil L to flow from the lower chamber 20 to the back pressure chamber 171A via the second passage 180A.

[0227] Next, the operation of the shock absorber 1A including the damping force generating mechanism 10A will be described.

[0228] {Low frequency and ultra-low speed range of stretching stroke x1}

[0229] In the low-frequency and ultra-low-speed range x1, the first valve mechanism 41A and the piston valve mechanism 201A do not open the valves. In addition, the oil L from the upper chamber 19 flows to the back pressure chamber 171A via a part of the rod-side passage 341 and the back pressure chamber introduction passage 176A. As a result, the partition member 111A of the frequency response mechanism 211A moves toward the disk 265 side and deforms. In this low-frequency and ultra-low-speed range x1, a large amount of oil L is introduced from the upper chamber 19 to the back pressure chamber 171A at the beginning of the stroke. Therefore, the partition member 111A of the frequency response mechanism 211A moves toward the disk 265 side until it is close to the limit and deforms, and then becomes difficult to deform. In addition, there is no fixed damping orifice that always connects the upper chamber 19 and the lower chamber 20 in the first valve mechanism 41A, 42A and the piston valve mechanism 201A. As a result, in the low-frequency and ultra-low-speed range x1, the increase rate of the damping force relative to the increase in the piston speed becomes high.

[0230] {Low frequency and low speed range of stretching stroke x2}

[0231] In the low-frequency and low-speed range x2, the oil L from the upper chamber 19 causes the dividing member 111A of the frequency response mechanism 211A to move and deform greatly toward the disk 265 side, as in the low-frequency and ultra-low-speed range x1. Then, it becomes difficult for the oil L from the upper chamber 19 to be introduced into the back-pressure chamber 171A via the rod-side passage 341 and the back-pressure chamber introduction passage 176A. In the low-frequency and low-speed range x2, the pressure of the back-pressure chamber 171A is higher than that in the low-frequency and ultra-low-speed range x1. Therefore, in the low-frequency and low-speed range x2, the oil L from the upper chamber 19 flows from the piston-side passage 43A to the lower chamber 20 by opening the damping valve 261 of the piston valve mechanism 201A. As a result, in the low-frequency and low-speed range x2, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency and ultra-low-speed range x1. In the low frequency and low speed range x2, the partition member 111A of the frequency response mechanism 211A moves to the limit and deforms, so the pressure in the back pressure chamber 171A becomes high pressure. Therefore, the first damping valve 52A of the first valve mechanism 41 is restricted from opening due to the large force from the back pressure chamber 171A.

[0232] {Low frequency, medium and high speed range of stretching stroke x3}

[0233] In the low-frequency, medium-speed range x3, the oil L from the upper chamber 19 opens the damping valve 261 of the piston valve mechanism 201A and flows from the piston side passage 43A to the lower chamber 20, as in the low-frequency, low-speed range x2. In the low-frequency, medium-speed range x3, the oil L flows from the piston side passage 43A to the lower chamber 20, thereby suppressing the pressure increase in the back pressure chamber 171A caused by the oil L introduced into the back pressure chamber 171A via a part of the rod side passage 341 and the back pressure chamber introduction passage 176A. In contrast, the force in the valve opening direction applied to the first valve mechanism 41A through the rod side passage 341 increases, so the oil L from the upper chamber 19 passes through the rod side passage 341 and opens the first damping valve 52A of the first valve mechanism 41A and flows to the lower chamber 20. As a result, in the low-frequency, medium-speed range x3, the increase rate of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency, low-speed range x2.

[0234] {High frequency ultra-low speed range of stretching stroke x4}

[0235] In the high-frequency ultra-low-speed range x4, the first valve mechanism 41A and the piston valve mechanism 201A do not open the valves. In addition, the oil L from the upper chamber 19 flows to the back pressure chamber 171A through a part of the rod side passage 341 and the back pressure chamber introduction passage 176A as in the low-frequency ultra-low-speed range x1. As a result, the dividing component 111A of the frequency response mechanism 211A moves toward the disc 265 and deforms. In this high-frequency ultra-low-speed range x4, the oil L introduced from the upper chamber 19 to the back pressure chamber 171A is less than that in the low-frequency ultra-low-speed range x1. Therefore, the dividing component 111A of the frequency response mechanism 211A is not deformed to the limit and is easy to deform. As a result, the oil L introduced from the upper chamber 19 to the back pressure chamber 171A can be absorbed by the movement and deformation of the dividing component 111A. Therefore, in the high-frequency ultra-low-speed range x4, although the increase rate of the damping force relative to the increase in piston speed becomes higher, the damping force at the same piston speed becomes lower than that in the low-frequency ultra-low-speed range x1, and a soft characteristic is obtained.

[0236] {High frequency, low, medium and high speed range of stretching stroke x5}

[0237] In the high-frequency, low-medium, and high-speed range x5, the oil L from the upper chamber 19 causes the partition member 111A of the frequency response mechanism 211A to move toward the disk 265 and deform as in the high-frequency, ultra-low-speed range x4. In the high-frequency, low-medium, and high-speed range x5, the oil L introduced into the back pressure chamber 171A is small, so the pressure rise in the back pressure chamber 171A is suppressed by the deformation of the partition member 111A. Therefore, the force from the back pressure chamber 171A on the first damping valve 52A of the first valve mechanism 41A becomes smaller, and the first damping valve 52A becomes easier to open. Therefore, the oil L from the upper chamber 19 flows toward the lower chamber 20 through the rod-side passage 341 and opens the first damping valve 52A of the first valve mechanism 41A. As a result, in the high-frequency, low-medium, and high-speed range x5, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency, ultra-low-speed range x4. Furthermore, in the high frequency low, medium and high speed range x5, the damping force at the same piston speed becomes lower than that in the low frequency low speed range x2 and the low frequency medium and high speed range x3, becoming a soft characteristic. In this high frequency low, medium and high speed range x5, the piston valve mechanism 201A maintains a closed valve state.

[0238] {Low frequency and ultra-low speed range of contraction stroke y1}

[0239] In the low-frequency and ultra-low-speed range y1, the first valve mechanism 42A and the communication mechanism 181A do not open the valves. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172A of the first passage 173A. As a result, the partition member 111A of the frequency response mechanism 211A moves toward the bottom surface side of the seal groove 68A and deforms. In this low-frequency and ultra-low-speed range y1, a large amount of oil L is introduced from the lower chamber 20 to the variable chamber 172A at the beginning of the stroke. Therefore, the partition member 111A of the frequency response mechanism 211A moves to the bottom surface side of the seal groove 68A until it reaches the limit and deforms, becoming difficult to deform. In addition, there is no fixed damping hole that always connects the lower chamber 20 and the upper chamber 19 in the first valve mechanism 41A, 42A and the piston valve mechanism 201A. As a result, in the low-frequency and ultra-low-speed range y1, the increase rate of the damping force relative to the increase in the piston speed becomes high, and it becomes a hard characteristic.

[0240] {Low frequency and low speed range of contraction stroke y2}

[0241] In the low-frequency and low-speed range y2, the oil L from the lower chamber 20 moves the dividing member 111A to the bottom side of the sealing groove 68A until it is close to the limit and deforms, as in the low-frequency and ultra-low-speed range y1, and then opens the connecting mechanism 181A to flow from the second passage 180A to the upper chamber 19 via the back pressure chamber 171A, the back pressure chamber introduction passage 176A, and a part of the rod side passage 341. As a result, in the low-frequency and low-speed range y2, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency and ultra-low-speed range y1.

[0242] {Low frequency, medium and high speed range of contraction stroke y3}

[0243] In the low-frequency, medium-high speed range y3, as in the low-frequency, low-speed range y2, the oil L from the lower chamber 20 flows from the second passage 180A to the upper chamber 19 via the back pressure chamber 171A, the back pressure chamber introduction passage 176A, and a portion of the rod side passage 341 by opening the communication mechanism 181A. In the low-frequency, low-medium-high speed range y2, in addition, the oil L from the lower chamber 20 flows to the upper chamber 19 by opening the first damping valve 231A of the first valve mechanism 42A through the piston side passage 44. As a result, in the low-frequency, medium-high speed range y3, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency, low-speed range y2.

[0244] {High frequency ultra-low speed range of contraction stroke y4}

[0245] In the high-frequency ultra-low speed range y4, the first valve mechanism 42A and the connecting mechanism 181A do not open the valves. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172A. As a result, the dividing component 111A of the frequency response mechanism 211A moves toward the bottom side of the sealing groove 68A and deforms. In this high-frequency ultra-low speed range y4, the piston frequency is high frequency and the stroke of the piston 18A is small, so the oil L introduced from the lower chamber 20 to the variable chamber 172A becomes less than that in the low-frequency ultra-low speed range y1. Therefore, the dividing component 111A of the frequency response mechanism 211A is not deformed to the limit and is easy to move and deform. As a result, the oil L introduced from the lower chamber 20 to the variable chamber 172A can be absorbed by the movement and deformation of the dividing component 111A. Therefore, in the high-frequency ultra-low speed range y4, the damping force at the same piston speed is softer than that in the low-frequency ultra-low speed range y1.

[0246] {High frequency and low speed range of contraction stroke y5}

[0247] In the high-frequency and low-speed range y5, the oil L from the lower chamber 20 flows from the first passage 173A to the upper chamber 19 via the back pressure chamber 171A, the back pressure chamber introduction passage 176A, and a portion of the rod side passage 341 by opening the valve of the communication mechanism 181A. In the high-frequency and low-speed range y5, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency and ultra-low-speed range y4. In addition, in the high-frequency and low-speed range y5, the damping force at the same piston speed becomes lower and softer than that in the low-frequency and low-speed range y2.

[0248] {High frequency, medium and high speed range of contraction stroke y6}

[0249] In the high-frequency, medium-high speed range y6, as in the high-frequency, low-speed range y5, the oil L from the lower chamber 20 flows from the first passage 173A to the upper chamber 19 via the back pressure chamber 171A, the back pressure chamber introduction passage 176A, and a portion of the rod side passage 341 by opening the connecting mechanism 181A. In the high-frequency, medium-high speed range y6, in addition, the oil L from the lower chamber 20 flows to the upper chamber 19 by opening the first damping valve 231A of the first valve mechanism 42A through the piston side passage 44A. As a result, in the high-frequency, medium-high speed range y6, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency, low-speed range y5. In addition, in the high-frequency, medium-high speed range y6, the damping force at the same piston speed becomes lower and softer than that in the low-frequency, medium-high speed range y3.

[0250] The damping force generating mechanism 10A of the second embodiment includes a pilot housing 58A, a frequency response mechanism 211A, a second passage 180A, and a communication mechanism 181A. The pilot housing 58A is a bottomed cylindrical shape and is formed with a back pressure chamber 171A that generates a force in the valve closing direction for the first damping valve 52A disposed on the opening 67A side. The frequency response mechanism 211A is provided with a partition member 111A having sealing portions 112A and 113A that seal the first passage 173A with an elastic member in a movably manner in the first passage 173A that is provided at the bottom 65A of the pilot housing 58A and connects the back pressure chamber 171A and the lower chamber 20, so that the force in the valve closing direction for the first damping valve 52A is variable. The second passage 180A is provided in parallel with the first passage 173A, and one side can be communicated with the back pressure chamber 171A. The communication mechanism 181A is located on the one side of the second passage 180A, and can communicate with the other side of the second passage 180A only when the lower chamber 20 is located on the upstream side.

[0251] As described above, the damping force generating mechanism 10A is provided with the first passage 173A which connects and extends the back pressure chamber 171A and the lower chamber 20 at the bottom 65A of the pilot housing 58A forming the back pressure chamber 171A. In addition, the damping force generating mechanism 10A is provided with the frequency response mechanism 211A in the first passage 173A in a manner that allows the partition member 111A which seals the first passage 173A with the sealing parts 112A and 113A to be movably provided, so that the force acting on the first damping valve 52A in the valve closing direction is variable. Therefore, although the damping force generating mechanism 10A has the frequency response mechanism 211A, it is possible to suppress the size increase.

[0252] Furthermore, the damping force generating mechanism 10A is provided with a connecting mechanism 181A, so when the stroke is reversed from the contraction stroke to the extension stroke, the connecting mechanism 181A opens the valve, and the oil L is introduced from the lower chamber 20, which is at a higher pressure than the upper chamber 19 in the contraction stroke, to the back pressure chamber 171A via the second passage 180A, so that the pressure of the back pressure chamber 171A can be quickly increased. As a result, the closed valve state of the first damping valve 52A, which is urged in the valve closing direction by the pressure in the back pressure chamber 171A, is stabilized. Thus, the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke can be suppressed.

[0253] Furthermore, the damping force generating mechanism 10A is configured such that the second passage 180A opened and closed by the communication mechanism 181A is disposed on the inner peripheral side of the bottom portion 65A relative to the first passage 173A, and thus an increase in radial size can be suppressed.

[0254] Furthermore, since the damping force generating mechanism 10A uses an O-ring as the partitioning member 111A having the sealing portions 112A and 113A that seal the first passage 173A by means of an elastic member, the compression deformation is large. Thus, the effect of suppressing the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke by providing the connecting mechanism 181A is high.

[0255] It should be noted that, in the damping force generating mechanism 10A, if Figure 8 As shown in FIG. 1 , a sintered disk 264A may be provided in place of the disks 264 and 265. The disk 264A has the same outer diameter as the disk 264. Fig. 9 As shown, a notch 267A is formed on the outer periphery. A plurality of notches 267A are provided on the disk 264A at equal intervals along the circumferential direction thereof. The passages in the plurality of notches 267A of the disk 264A communicate with the variable chamber 172A and the lower chamber 20. In this case, the disk 263 can also be provided with a plurality of sheets and rigidity can be ensured.

[0256] [Third Embodiment]

[0257] Then, mainly based on Figure 10 to Figure 12 The third embodiment will be described with the focus on the parts that are different from the second embodiment. It should be noted that the parts that are common to the second embodiment are represented by the same names and the same symbols.

[0258] like Fig.10 As shown, the structure of a part of the damping force generating mechanism 10B of the shock absorber 1B including the damping force generating mechanism 10B of the third embodiment is different from that of the damping force generating mechanism 10A. The structure between the disk 262 and the nut 235 in the axial direction of the piston rod 21A of the damping force generating mechanism 10B is different from that of the damping force generating mechanism 10A.

[0259] The damping force generating mechanism 10B includes a seat forming member 351 and a first damping valve 52B (first damping force generating member) in this order from the disk 262 side in the axial direction of the piston rod 21A.

[0260] The seat forming member 351 is made of metal and is integrally formed by sintering so as to be seamless as a whole. The seat forming member 351 includes a body portion 352 , a flange portion 353 , an inner seat portion 354 , an intermediate seat portion 355 , and a valve seat portion 356 .

[0261] The body portion 352 is cylindrical, and the mounting shaft portion 28A of the piston rod 21A is fitted on the inner peripheral side thereof.

[0262] The flange portion 353 extends from one end side in the axial direction of the body portion 352 toward the outer side in the radial direction of the body portion 352. The flange portion 353 is in the shape of a disk.

[0263] The inner seat portion 354 protrudes from the inner peripheral side of the end portion of the body portion 352 on the same side as the flange portion 353 in the axial direction along the axial direction of the body portion 352. The inner seat portion 354 is annular.

[0264] The intermediate seat portion 355 protrudes from the vicinity of the boundary between the body portion 352 and the flange portion 353 toward the same side as the inner seat portion 354 in the axial direction of the body portion 352 and the flange portion 353. The intermediate seat portion 355 is annular and surrounds the inner seat portion 354 radially outward.

[0265] The valve seat portion 356 protrudes from the outer peripheral portion of the flange portion 353 toward the same side as the intermediate seat portion 355 in the axial direction of the flange portion 353. The valve seat portion 356 is annular and surrounds the intermediate seat portion 355 on the radially outer side.

[0266] The seat forming member 351 has passage grooves 358 formed at the ends of the inner seat portion 354 and the middle seat portion 355 in the axial direction of the inner seat portion 354, the middle seat portion 355, the trunk portion 352, and the flange portion 353. The passage grooves 358 penetrate the inner seat portion 354 and the middle seat portion 355 in their radial direction. The passage grooves 358 are connected to the passage grooves 30A of the piston rod 21A.

[0267] The seat forming member 351 abuts against the disk 262 at an end portion of the body portion 352 on the opposite side from the flange portion 353 in the axial direction.

[0268] The first damping valve 52B is made of metal and is a circular flat plate with a hole of a constant thickness. The first damping valve 52B is formed by stamping. The first damping valve 52B is fitted with the mounting shaft portion 28A of the piston rod 21A on its inner side. The outer diameter of the first damping valve 52B is equal to the outer diameter of the valve seat portion 356. The first damping valve 52B opens and closes the passage between the valve seat portion 356 by seating on the valve seat portion 356 and leaving the valve seat portion 356.

[0269] The damping force generating mechanism 10B includes a housing member 360 and a pressing member 361 on the opposite side of the seat forming member 351 in the axial direction of the first damping valve 52B.

[0270] The case member 360 is made of metal and is integrally formed by sintering without any joints. The case member 360 is in the shape of a bottomed cylinder and has a bottom 365 and a cylindrical portion 366 .

[0271] The bottom portion 365 is in the shape of a disk having a hole, and the mounting shaft portion 28A of the piston rod 21A is fitted on the inner peripheral side thereof.

[0272] The cylindrical portion 366 is cylindrical and extends from the outer peripheral portion of the bottom portion 365 to one side along the axial direction of the bottom portion 365. The side of the case member 360 opposite to the bottom portion 365 in the axial direction of the cylindrical portion 366 is an opening 367.

[0273] The bottom portion 365 has a bottom body portion 371 , a side seat portion 372 , and another side seat portion 373 .

[0274] The bottom body part 371 is a circular plate with a hole, and the mounting shaft part 28A of the piston rod 21A is fitted on its inner circumference. On the bottom body part 371, a circular annular groove 375 is formed on the outer circumference. A passage hole 376 is formed on the bottom body part 371, which passes through the bottom body part 371 in the axial direction. The passage hole 376 is located on the inner side of the bottom body part 371 in the radial direction of the bottom body part 371 than the annular groove 375.

[0275] The one-side seat portion 372 protrudes from the inner peripheral side of the end portion of the bottom body portion 371 on the side opposite to the cylindrical portion 366 in the axial direction to the side opposite to the cylindrical portion 366 along the axial direction of the bottom body portion 371. The one-side seat portion 372 is annular. The housing member 360 abuts against the inner peripheral side of the first damping valve 52B at the one-side seat portion 372.

[0276] The one-side seat portion 372 includes a large diameter portion 381 and a small diameter portion 382. In the axial direction of the one-side seat portion 372, the large diameter portion 381 is located on the bottom body portion 371 side compared to the small diameter portion 382. The outer diameter of the large diameter portion 381 is larger than the outer diameter of the small diameter portion 382. A passage groove 383 is formed at the end of the small diameter portion 382 on the side opposite to the large diameter portion 381 in the axial direction of the small diameter portion 382 of the one-side seat portion 372. The passage groove 383 penetrates the small diameter portion 382 in the radial direction of the small diameter portion 382. The passage groove 383 is connected to the passage groove 30A of the piston rod 21A.

[0277] The other side seat portion 373 protrudes from the inner peripheral side of the end portion of the bottom body portion 371 on the cylindrical portion 366 side in the axial direction toward the same side as the cylindrical portion 366 along the axial direction of the bottom body portion 371. The other side seat portion 373 is annular.

[0278] The passage hole 376 of the bottom body portion 371 is provided radially outward of the one side seat portion 372 in the radial direction of the bottom body portion 371 , and is provided between the other side seat portion 373 and the cylindrical portion 366 .

[0279] The pressing member 361 has a cylindrical portion 391 and an inner protrusion 392. The cylindrical portion 391 is cylindrical. The inner protrusion 392 expands from one end of the cylindrical portion 391 in the axial direction toward the inner side in the radial direction of the cylindrical portion 391. The inner protrusion 392 is annular.

[0280] When the inner protrusion 392 of the pressing member 361 is located closer to the first damping valve 52B than the cylindrical portion 391 in the axial direction, the cylindrical portion 391 is fitted with the outer peripheral portion of the bottom body portion 371 of the housing member 360. The pressing member 361 is axially slidable relative to the housing member 360. The pressing member 361 abuts against the outer peripheral side of the first damping valve 52B at the end portion of the inner protrusion 392 in the axial direction.

[0281] The damping force generating mechanism 10B includes a spring member 401 and a sealing member 402 .

[0282] The spring component 401 is made of a metal plate and is formed by stamping. The spring component 401 has a perforated circular plate-shaped base plate portion 405 and an elastic plate portion 406 extending from the base plate portion 405 to the outside in the radial direction of the base plate portion 405. A plurality of elastic plate portions 406 are provided on the spring component 401 at equal intervals along the circumferential direction of the base plate portion 405.

[0283] The base plate portion 405 of the spring member 401 is fitted with the small diameter portion 382 of the one side seat portion 372 of the housing member 360 on its inner circumferential side and is placed on the end surface of the large diameter portion 381 on the side of the small diameter portion 382 in the axial direction. The plurality of elastic plate portions 406 of the spring member 401 abut against the end surface of the inner protrusion 392 of the pressing member 361 on the side opposite to the first damping valve 52B in the axial direction. In this state, the plurality of elastic plate portions 406 of the spring member 401 are elastically deformed and the first damping valve 52B is pressed against the valve seat portion 356 by applying force to the first damping valve 52B via the pressing member 361.

[0284] The sealing member 402 is annular and fits into the annular groove 375 of the housing member 360. The sealing member 402 is made of an elastic material having sealing properties, specifically, rubber. The sealing member 402 is an O-ring and always seals the gap between the bottom body portion 371 and the cylindrical portion 391 of the pressing member 361.

[0285] The damping force generating mechanism 10B has an opening and closing disc 57B, a partitioning member 111B (movable mechanism), and a stopper member 411 in order from the other side seat portion 373 side, with the shaft portion 28A being fitted on the inner sides of each of the two, on the side opposite to the first damping valve 52B in the axial direction of the housing member 360. The nut 235 abuts against the end face of the stopper member 411 on the side opposite to the partitioning member 111B in the axial direction.

[0286] The dividing part 111B is as follows Fig.11 As shown, it is composed of a disk 421 and a gasket 422.

[0287] The disk 421 is made of metal and is a circular flat plate with a hole of a constant thickness. The disk 421 is formed by stamping. The mounting shaft portion 28A of the piston rod 21A is fitted on the inner circumference of the disk 421. A passage hole 425 is formed in the middle portion of the disk 421 in the radial direction. The passage hole 425 penetrates the disk 421 in the axial direction of the disk 421. A plurality of passage holes 425 are formed on the disk 421 at equal intervals along the circumferential direction of the disk 421.

[0288] The gasket 422 is made of an elastic material with sealing properties, specifically, rubber. The gasket 422 is annular. The gasket 422 is fixed to the outer peripheral side of the disk 421. The gasket 422 is fitted with the inner peripheral surface of the cylindrical portion 366 of the shell member 360 in a manner that covers the entire circumference. At that time, the gasket 422 contacts the inner peripheral surface of the cylindrical portion 366 at the sealing portion 112B of its outer peripheral portion. The gasket 422 can slide axially relative to the inner peripheral surface of the cylindrical portion 366. The gasket 422 always seals the gap between the dividing component 111B and the cylindrical portion 366. The passage hole 425 of the disk 421 is arranged on the inner side than the gasket 422 in the radial direction of the disk 421.

[0289] The opening and closing disc 57B is made of metal. The opening and closing disc 57B is a circular flat plate with a constant thickness and a hole, and is formed by stamping. The opening and closing disc 57B abuts against the disc 421 of the partitioning member 111B to block the passages in the plurality of passage holes 425. The opening and closing disc 57B opens the passages in the plurality of passage holes 425 by leaving the disc 421 of the partitioning member 111B.

[0290] The stop member 411 is made of metal and is in the shape of a circular plate with holes. The stop member 411 engages the mounting shaft portion 28A of the piston rod 21A on its inner circumference. On the stop member 411, a tapered portion 412 is provided at the radial middle position on the axial side of the dividing member 111B. The closer the tapered portion 412 is to the radial outer side of the stop member 411, the farther it is from the disk 421 of the dividing member 111B in the axial direction of the stop member 411. On the stop member 411, a passage hole 431 is formed at the radial middle position of the tapered portion 412. The passage hole 431 penetrates the stop member 411 along the axial direction of the stop member 411. When the dividing member 111B is deformed toward the stop member 411 side and the disk 421 abuts against the tapered portion 412, further deformation, i.e., movement, is restricted.

[0291] The stopper member 411 is provided to cover the opening 367 of the cylindrical portion 366 of the case member 360. The outer diameter of the stopper member 411 is smaller than the inner diameter of the cylindrical portion 366 of the case member 360. The nut 235 abuts against the axial side of the stopper member 411 opposite to the partition member 111B.

[0292] like Fig.10As shown, the housing member 360, the pressing member 361, the spring member 401, the sealing member 402 and the stop member 411 of the damping force generating mechanism 10B constitute the pilot housing 58B (force generating member). The bottom body portion 371 of the housing member 360 of the pilot housing 58B, the other side seat portion 373, the cylindrical portion 366 and the stop member 411 form the bottom portion 65B. The portion of the pilot housing 58B that extends in the axial direction of the pressing member 361 further to the side opposite to the stop member 411 than the bottom body portion 371 of the housing member 360 forms the cylindrical portion 66B. The side of the pilot housing 58B that is opposite to the bottom portion 65B in the axial direction of the cylindrical portion 66B is the opening portion 67B.

[0293] The pilot housing 58B has a tapered portion 412 inside its bottom 65B. The passage in the passage hole 431 of the pilot housing 58B is provided between the tapered portion 412 and the outer bottom side of the bottom 65B so as to always communicate with the lower chamber 20 .

[0294] The passage in the passage groove 30A of the piston rod 21A, the passage in the passage groove 358 of the seat forming component 351, the passage between the inner seat portion 354 and the middle seat portion 355 of the seat forming component 351, and the passage between the middle seat portion 355 of the seat forming component 351 and the valve seat portion 356 constitute the rod side passage 341B.

[0295] The first damping valve 52B opens and closes the rod-side passage 341B by coming into contact with and separating from the valve seat portion 356 .

[0296] The first damping valve 52B is provided in the rod side passage 341B, and suppresses the flow of the oil L generated by the sliding of the piston 18A toward the tension side and generates a damping force. The first damping valve 52B constitutes the first valve mechanism 41B together with the valve seat portion 356 of the seat forming component 351. The first damping valve 52B is opened by leaving the seat from the valve seat portion 356. Thus, the first damping valve 52B allows the oil L from the rod side passage 341B to flow toward the lower chamber 20 via the valve seat portion 356. The rod side passage 341B becomes a passage on the tension side through which the oil L in the upper chamber 19 flows due to the movement of the piston 18A toward the upper chamber 19 side. The rod side passage 341B becomes a passage on the tension side through which the oil L as the working fluid flows from the upper chamber 19 on one side toward the lower chamber 20 on the other side during the tension stroke. The first valve mechanism 41B on the tension side, which is composed of the valve seat portion 356 and the first damping valve 52B, is provided in the rod-side passage 341B. The first damping valve 52B opens and closes the rod-side passage 341B to suppress the flow of the oil L, thereby generating a damping force.

[0297] The first valve mechanism 41B on the extension side does not form a fixed damping hole that allows the upper chamber 19 and the lower chamber 20 to communicate even if they are in abutment, either in the valve seat portion 356 or in the first damping valve 52B that abuts against the valve seat portion 356. That is, the first valve mechanism 41B on the extension side does not form a fixed damping hole that allows the upper chamber 19 and the lower chamber 20 to always communicate. The rod side passage 341B becomes a passage on the upstream side of the first damping valve 52B in the flow direction of the oil L in the extension stroke. The lower chamber 20 is on the downstream side of the first damping valve 52B in the flow direction of the oil L in the extension stroke.

[0298] The sealing portion 112B of the partition member 111B is pressed against the inner peripheral surface of the cylindrical portion 366 of the housing member 360 in a manner covering the entire circumference. As a result, the portion surrounded by the first damping valve 52B, the housing member 360, the pressing member 361, the sealing member 402, the opening and closing disc 57B, and the partition member 111B becomes the back pressure chamber 171B. The back pressure chamber 171B is always connected to the passage in the passage groove 30A of the piston rod 21A via the passage in the passage groove 383 of the pilot housing 58B.

[0299] The portion surrounded by the partition member 111B and the stopper member 411 forms the variable chamber 172B. The variable chamber 172B is always in communication with the lower chamber 20 via the passage in the passage hole 431 of the stopper member 411.

[0300] The bottomed cylindrical pilot housing 58B has a back pressure chamber 171B formed therein by the first damping valve 52B, the opening and closing disk 57B and the partition member 111B. The partition member 111B is provided in the pilot housing 58B and partitions the pilot housing 58B into the back pressure chamber 171B and the variable chamber 172B.

[0301] The passage in the passage groove 30A of the piston rod 21A and the passage in the passage groove 383 of the pilot housing 58B constitute a back pressure chamber introduction passage 176B that branches from the rod side passage 341B and communicates with the back pressure chamber 171B. The back pressure chamber introduction passage 176B communicates the upper chamber 19 and the back pressure chamber 171B via the rod side passage 341B. The back pressure chamber introduction passage 176B introduces the oil L from the upper chamber 19 on the upstream side of the back pressure chamber 171B to the back pressure chamber 171B during the extension stroke.

[0302] The passage in the passage hole 431 of the stopper member 411, the variable chamber 172B, and the passage in the passage hole 425 of the partition member 111B constitute a first passage 173B extending and connecting the back pressure chamber 171B and the lower chamber 20. The partition member 111B having a sealing portion 112B for sealing the first passage 173B by an elastic member is movably provided in the first passage 173B.

[0303] The back pressure chamber 171B causes the internal pressure to act on the first damping valve 52B in the valve closing direction along the direction of the seat forming member 351, that is, to seat the first damping valve 52B on the valve seat portion 356. The pilot housing 58B is a bottomed cylindrical shape and is formed with the back pressure chamber 171B that generates a force in the valve closing direction for the first damping valve 52B disposed on the opening portion 67B side.

[0304] The opening and closing disc 57B is provided between the first passage 173B and the back pressure chamber 171B in an openable and closable manner. The opening and closing disc 57B cuts off the flow of the oil L between the back pressure chamber 171B, the first passage 173B, and the lower chamber 20 when the opening and closing disc 57B abuts against the disc 421 of the partition member 111B in a surface contact manner. In addition, the opening and closing disc 57B allows the flow of the oil L between the back pressure chamber 171B, the first passage 173B, and the lower chamber 20 when the opening and closing disc 57B is separated from the disc 421 of the partition member 111B.

[0305] Here, the opening and closing disc 57B allows the flow of the oil L from the lower chamber 20 to the back pressure chamber 171B via the first passage 173B when the pressure on the lower chamber 20 side is higher than the pressure on the back pressure chamber 171B side by a predetermined value or more. The opening and closing disc 57B restricts the flow of the oil L from the back pressure chamber 171B to the lower chamber 20 via the first passage 173B when the pressure on the back pressure chamber 171B side is higher than the pressure on the lower chamber 20 side.

[0306] The opening and closing disc 57B and the disc 421 including the passage hole 425 of the dividing member 111B constitute a communication mechanism 181B. One side of the first passage 173B can communicate with the back pressure chamber 171B. The communication mechanism 181B is located on the one side of the first passage 173B, and can communicate with the other side of the first passage 173B, that is, the lower chamber 20 side, only when the lower chamber 20 is on the upstream side. In other words, the communication mechanism 181B cannot communicate with the other side of the first passage 173B, that is, the lower chamber 20 side, when the lower chamber 20 is on the downstream side. The communication mechanism 181B restricts the flow of the oil L in one direction from the back pressure chamber 171B side to the variable chamber 172B side between the back pressure chamber 171B and the variable chamber 172B. On the other hand, the communication mechanism 181B allows the flow of the oil L in the other direction from the variable chamber 172B side to the back pressure chamber 171B side. The communication mechanism 181B is a one-way valve, and the opening and closing disc 57B is a valve member of the communication mechanism 181B.

[0307] The partitioning member 111B has a disc 421 including a passage hole 425 and a gasket 422. The opening and closing disc 57B can block the passage hole 425. The opening and closing disc 57B opens the valve when the first passage 173B allows the oil L to flow from the lower chamber 20 to the back pressure chamber 171B. The first passage 173B is provided to connect the back pressure chamber 171B and the lower chamber 20, and the partitioning member 111B is provided. The first passage 173B provided with the partitioning member 111B also serves as a passage in which one side can be communicated with the back pressure chamber 171B and a communication mechanism 181B is provided, and the communication mechanism 181B is located on the one side and can be communicated with the other side only when the lower chamber 20 side is located on the upstream side.

[0308] The communication mechanism 181B restricts the flow of the oil L from the upper chamber 19, the rod side passage 341B, the back pressure chamber introduction passage 176B, and the back pressure chamber 171B to the lower chamber 20 via the first passage 173B. The communication mechanism 181B allows the flow of the oil L from the lower chamber 20 to the back pressure chamber 171B, the back pressure chamber introduction passage 176B, the rod side passage 341B, and the upper chamber 19 via the first passage 173B.

[0309] The pilot housing 58B and the partitioning member 111B constitute a frequency response mechanism 211B that makes the damping force variable in response to the piston frequency. The partitioning member 111B of the frequency response mechanism 211B moves and deforms according to the frequency of the reciprocating motion of the piston 18A, so that the capacity of the back pressure chamber 171B that is always connected to the upper chamber 19 and the capacity of the variable chamber 172B that is always connected to the lower chamber 20 are changed. The frequency response mechanism 211B has the partitioning member 111B that is movably provided in the first passage 173B. The frequency response mechanism 211B makes the force acting on the first damping valve 52B based on the back pressure chamber 171B variable.

[0310] In the extension stroke, the pressure difference between the back pressure chamber 171B and the lower chamber 20 is higher on the back pressure chamber 171B side than on the lower chamber 20 side. Then, due to the pressure of the back pressure chamber 171B, the partition member 111B maintains the sealed state with the cylindrical portion 366 and deforms and moves toward the stop member 411 side together with the opening and closing disc 57B. As a result, the volume of the back pressure chamber 171B is expanded.

[0311] In the contraction stroke, the lower chamber 20 side is at a higher pressure than the back pressure chamber 171B side. Therefore, if the pressure difference between the lower chamber 20 side and the back pressure chamber 171B side is lower than the specified value, the dividing member 111B maintains the sealed state with the cylindrical portion 366 due to the pressure on the lower chamber 20 side, and deforms and moves to the side opposite to the stop member 411 together with the opening and closing disc 57B. As a result, the volume of the variable chamber 172B is expanded. In addition, in the contraction stroke, when the lower chamber 20 side becomes a higher pressure than the back pressure chamber 171B side by a specified value, the connecting mechanism 181B opens the valve to allow the oil L to flow from the lower chamber 20 to the back pressure chamber 171B.

[0312] Next, the operation of the shock absorber 1B including the damping force generating mechanism 10B will be described.

[0313] {Low frequency and ultra-low speed range of stretching stroke x1}

[0314] In the low-frequency and ultra-low-speed range x1, the first valve mechanism 41B and the piston valve mechanism 201A do not open the valves. In addition, the oil L from the upper chamber 19 flows to the back pressure chamber 171B via the rod side passage 341B and the back pressure chamber introduction passage 176B. As a result, the partition member 111B of the frequency response mechanism 211B deforms toward the stop member 411 together with the opening and closing disc 57B. In this low-frequency and ultra-low-speed range x1, a large amount of oil L is introduced from the upper chamber 19 to the back pressure chamber 171B at the beginning of the stroke. Therefore, the partition member 111B of the frequency response mechanism 211B deforms toward the stop member 411 together with the opening and closing disc 57B to the near limit, and then becomes difficult to deform. In addition, there is no fixed damping hole that always connects the upper chamber 19 and the lower chamber 20 in the first valve mechanism 41B, 42A and the piston valve mechanism 201A. As a result, in the low-frequency and ultra-low-speed range x1, the rate of increase of the damping force relative to the increase in the piston speed becomes high.

[0315] {Low frequency and low speed range of stretching stroke x2}

[0316] In the low-frequency and low-speed range x2, the oil L from the upper chamber 19 causes the partition member 111B of the frequency response mechanism 211B to be greatly deformed together with the opening and closing disc 57B toward the stop member 411 side, as in the low-frequency and ultra-low-speed range x1. Then, it becomes difficult for the oil L from the upper chamber 19 to be introduced into the back-pressure chamber 171B via the rod-side passage 341B and the back-pressure chamber introduction passage 176B. Therefore, in the low-frequency and low-speed range x2, the oil L from the upper chamber 19 flows from the piston-side passage 43A to the lower chamber 20 by opening the damping valve 261 of the piston valve mechanism 201A. As a result, in the low-frequency and low-speed range x2, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency and ultra-low-speed range x1. In this low-frequency and low-speed range x2, the partition member 111B of the frequency response mechanism 211B moves to the limit and deforms, so that the pressure in the back-pressure chamber 171B becomes high pressure. The first damping valve 52B of the first valve mechanism 41 is restricted from opening due to the large force from the back pressure chamber 171B.

[0317] {Low frequency, medium and high speed range of stretching stroke x3}

[0318] In the low-frequency, medium-speed range x3, the oil L from the upper chamber 19 flows from the piston side passage 43A to the lower chamber 20 by opening the damping valve 261 of the piston valve mechanism 201A as in the low-frequency, low-speed range x2. In the low-frequency, medium-speed range x3, the oil L flows from the piston side passage 43A to the lower chamber 20, thereby suppressing the pressure increase of the back pressure chamber 171B caused by the oil L introduced into the back pressure chamber 171B via a part of the rod side passage 341B and the back pressure chamber introduction passage 176B. In contrast, the force in the valve opening direction applied to the first valve mechanism 41B through the rod side passage 341B increases, so the oil L from the upper chamber 19 flows to the lower chamber 20 by opening the first damping valve 52B of the first valve mechanism 41B through the rod side passage 341B. As a result, in the low-frequency, medium-speed range x3, the increase rate of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency, low-speed range x2.

[0319] {High frequency ultra-low speed range of stretching stroke x4}

[0320] In the high-frequency ultra-low-speed range x4, the first valve mechanism 41B and the piston valve mechanism 201A do not open the valves. In addition, the oil L from the upper chamber 19 flows to the back pressure chamber 171B via the rod side passage 341B and the back pressure chamber introduction passage 176B as in the low-frequency ultra-low-speed range x1. As a result, the partition member 111B of the frequency response mechanism 211B deforms toward the stop member 411 together with the opening and closing disc 57B. In this high-frequency ultra-low-speed range x4, the oil L introduced from the upper chamber 19 to the back pressure chamber 171B is less than that in the low-frequency ultra-low-speed range x1. Therefore, the partition member 111B of the frequency response mechanism 211B is not deformed to the limit and is easy to deform. As a result, the oil L introduced from the upper chamber 19 to the back pressure chamber 171B can be absorbed by the deformation of the partition member 111B and the opening and closing disc 57B. Therefore, in the high-frequency ultra-low-speed range x4, although the increase rate of the damping force relative to the increase in piston speed becomes higher, the damping force at the same piston speed becomes lower than that in the low-frequency ultra-low-speed range x1, and a soft characteristic is obtained.

[0321] {High frequency, low, medium and high speed range of stretching stroke x5}

[0322] In the high-frequency, low-medium, and high-speed range x5, the oil L from the upper chamber 19 deforms the partition member 111B of the frequency response mechanism 211B together with the opening and closing disc 57B toward the stopper member 411 side, as in the high-frequency, ultra-low-speed range x4. In the high-frequency, low-medium, and high-speed range x5, the oil L introduced into the back pressure chamber 171B is small, so the pressure rise in the back pressure chamber 171B is suppressed by the deformation of the partition member 111B. Therefore, the force from the back pressure chamber 171B to the first damping valve 52B of the first valve mechanism 41B becomes smaller, and the first damping valve 52B becomes easier to open. Therefore, the oil L from the upper chamber 19 flows toward the lower chamber 20 through the rod-side passage 341B and opens the first damping valve 52B of the first valve mechanism 41B. As a result, in the high-frequency, low-medium, and high-speed range x5, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency, ultra-low-speed range x4. Furthermore, in the high frequency low, medium and high speed range x5, the damping force at the same piston speed becomes lower than that in the low frequency low speed range x2 and the low frequency medium and high speed range x3, and becomes a soft characteristic. In this high frequency low, medium and high speed range x5, the pressure rise in the back pressure chamber 171B is suppressed, so the piston valve mechanism 201A maintains the closed valve state.

[0323] {Low frequency and ultra-low speed range of contraction stroke y1}

[0324] In the low-frequency and ultra-low-speed range y1, the first valve mechanism 42A and the communication mechanism 181B do not open the valves. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172B of the first passage 173B. As a result, the partition member 111B of the frequency response mechanism 211B deforms to the side opposite to the stopper 411 together with the opening and closing disc 57B. In this low-frequency and ultra-low-speed range y1, a large amount of oil L is introduced from the lower chamber 20 to the variable chamber 172B at the beginning of the stroke. Therefore, the partition member 111B of the frequency response mechanism 211B deforms to the side opposite to the stopper 411 to the limit and becomes difficult to deform. In addition, there is no fixed damping hole that always connects the lower chamber 20 and the upper chamber 19 in the first valve mechanism 41B, 42A and the piston valve mechanism 201A. As a result, in the low-frequency and ultra-low-speed range y1, the increase rate of the damping force relative to the increase in the piston speed becomes high, and it becomes a hard characteristic.

[0325] {Low frequency and low speed range of contraction stroke y2}

[0326] In the low-frequency and low-speed range y2, the oil L from the lower chamber 20 moves the dividing member 111B to the side opposite to the stop member 411 until it is close to the limit and deforms, as in the low-frequency and ultra-low-speed range y1, and then opens the connecting mechanism 181B to flow from the first passage 173B through the back pressure chamber 171B, the back pressure chamber introduction passage 176B, and the rod side passage 341B to the upper chamber 19. As a result, in the low-frequency and low-speed range y2, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency and ultra-low-speed range y1.

[0327] {Low frequency, medium and high speed range of contraction stroke y3}

[0328] In the low-frequency, medium-high speed range y3, as in the low-frequency, low-speed range y2, the oil L from the lower chamber 20 flows from the first passage 173B to the upper chamber 19 via the back pressure chamber 171B, the back pressure chamber introduction passage 176B, and the rod side passage 341B by opening the communication mechanism 181B. In the low-frequency, medium-high speed range y2, in addition, the oil L from the lower chamber 20 flows through the piston side passage 44 to open the first damping valve 231A of the first valve mechanism 42A and flows to the upper chamber 19. As a result, in the low-frequency, medium-high speed range y3, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency, low-speed range y2.

[0329] {High frequency ultra-low speed range of contraction stroke y4}

[0330] In the high-frequency ultra-low speed range y4, the first valve mechanism 42A and the communication mechanism 181B do not open the valves. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172B. As a result, the partition member 111B of the frequency response mechanism 211B deforms to the side opposite to the stop member 411 together with the opening and closing disc 57B. In this high-frequency ultra-low speed range y4, the piston frequency is high frequency and the stroke of the piston 18A is small, so the oil L introduced from the lower chamber 20 to the variable chamber 172B becomes less than that in the low-frequency ultra-low speed range y1. Therefore, the partition member 111B of the frequency response mechanism 211B is not deformed to the limit and is easy to move and deform. As a result, the oil L introduced from the lower chamber 20 to the variable chamber 172B can be absorbed by the movement and deformation of the partition member 111B. Therefore, in the high-frequency ultra-low speed range y4, the damping force at the same piston speed is softer than that in the low-frequency ultra-low speed range y1.

[0331] {High frequency and low speed range of contraction stroke y5}

[0332] In the high-frequency and low-speed range y5, the oil L from the lower chamber 20 flows from the first passage 173B to the upper chamber 19 via the back pressure chamber 171B, the back pressure chamber introduction passage 176B, and the rod side passage 341B by opening the valve of the communication mechanism 181B. In the high-frequency and low-speed range y5, the rate of increase of the damping force relative to the increase of the piston speed becomes lower than that in the high-frequency and ultra-low-speed range y4. In addition, in the high-frequency and low-speed range y5, the damping force at the same piston speed becomes lower and softer than that in the low-frequency and low-speed range y2.

[0333] {High frequency, medium and high speed range of contraction stroke y6}

[0334] In the high-frequency, medium-high speed range y6, as in the high-frequency, low-speed range y5, the oil L from the lower chamber 20 flows from the first passage 173B to the upper chamber 19 via the back pressure chamber 171B, the back pressure chamber introduction passage 176B, and the rod side passage 341B by opening the connecting mechanism 181B. In the high-frequency, medium-high speed range y6, in addition, the oil L from the lower chamber 20 flows to the upper chamber 19 by opening the first damping valve 231A of the first valve mechanism 42A through the piston side passage 44A. As a result, in the high-frequency, medium-high speed range y6, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the high-frequency, low-speed range y5. In addition, in the high-frequency, medium-high speed range y6, the damping force at the same piston speed becomes lower and softer than that in the low-frequency, medium-high speed range y3.

[0335] The damping force generating mechanism 10B of the third embodiment includes a pilot housing 58B, a frequency response mechanism 211B, a first passage 173B, and a communication mechanism 181B. The pilot housing 58B is a bottomed cylindrical shape and is formed with a back pressure chamber 171B that generates a force in the valve closing direction for the first damping valve 52B disposed on the opening 67B side. The frequency response mechanism 211B is provided with a partition member 111B having a sealing portion 112B that seals the first passage 173B by an elastic member in a movably manner in the first passage 173B that is provided at the bottom 65B of the pilot housing 58B and that enables the back pressure chamber 171B to communicate with the lower chamber 20, so that the force in the valve closing direction for the first damping valve 52B is variable. One side of the first passage 173B can communicate with the back pressure chamber 171B. The communication mechanism 181B is located on the one side of the first passage 173B and can communicate with the other side of the first passage 173B only when the lower chamber 20 is on the upstream side.

[0336] As described above, the damping force generating mechanism 10B is provided with the first passage 173B that enables the back pressure chamber 171B and the lower chamber 20 to communicate with each other at the bottom 65B of the pilot housing 58B that forms the back pressure chamber 171B. In addition, the damping force generating mechanism 10B is provided with the frequency response mechanism 211B that is movably provided in the first passage 173B with the partition member 111B that seals the first passage 173B with the sealing portion 112B, so that the force acting on the first damping valve 52B in the valve closing direction is variable. Therefore, although the damping force generating mechanism 10B has the frequency response mechanism 211B, it is possible to suppress the size increase.

[0337] Furthermore, the damping force generating mechanism 10B is provided with a connecting mechanism 181B, so when the stroke is reversed from the contraction stroke to the extension stroke, the connecting mechanism 181B opens the valve, and the oil L is introduced from the lower chamber 20, which is at a higher pressure than the upper chamber 19 in the contraction stroke, to the back pressure chamber 171B via the first passage 173B, so that the pressure of the back pressure chamber 171B can be quickly increased. As a result, the closed valve state of the first damping valve 52B, which is urged in the valve closing direction by the pressure of the back pressure chamber 171B, is stabilized. Thus, the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke can be suppressed.

[0338] Furthermore, the first passage 173B provided with the partition member 111B of the damping force generating mechanism 10B also serves as a passage in which one side can communicate with the back pressure chamber 171B and a communicating mechanism 181B is provided, and the communicating mechanism 181B is located on the one side and can communicate with the other side only when the lower chamber 20 side is located on the upstream side. Thus, the size of the damping force generating mechanism 10B can be further suppressed.

[0339] Furthermore, the damping force generating mechanism 10B is provided with a tapered portion 412 inside the bottom portion 65B of the pilot housing 58B. Furthermore, when the partition member 111B of the damping force generating mechanism 10B is deformed toward the stop member 411, the deformation, i.e., the movement, is restricted by the tapered portion 412. Therefore, the local deformation of the partition member 111B can be suppressed, and its durability is improved.

[0340] The damping force generating mechanism 10B has a passage formed in the passage hole 431 in the pilot housing 58B between the tapered portion 412 and the outer bottom side of the bottom portion 65B and capable of always communicating with the lower chamber 20. Therefore, the damping force generating mechanism 10B can suppress an increase in the size of the pilot housing 58B.

[0341] Furthermore, the partition member 111B of the damping force generating mechanism 10B includes a disk 421 having a passage hole 425 and a gasket 422. Furthermore, the opening and closing disk 57B can block the passage hole 425 and open the valve when the first passage 173B allows the oil L to flow from the lower chamber 20 to the back pressure chamber 171B. Therefore, the variable volume of the back pressure chamber 171B can be increased while suppressing the enlargement of the damping force generating mechanism 10B.

[0342] It should be noted that, in the damping force generating mechanism 10B, Fig.12 As shown in the figure, the outer diameter of the flat plate-shaped opening and closing disc 57B is increased, and the outer peripheral portion of the opening and closing disc 57B is brought into contact with the inner peripheral portion of the gasket 422 on the side opposite to the disc 421 in the axial direction of the opening and closing disc 57B. As a result, the opening and closing disc 57B can be bent in a tapered shape and a pre-pressure can be applied to the opening and closing disc 57B. As a result, especially in the extension stroke, it is possible to suppress the oil L from leaking from the back pressure chamber 171B to the lower chamber 20 side via the communication mechanism 181B.

[0343] [Fourth Embodiment]

[0344] Then, mainly based on Fig.13 and Fig.14 The fourth embodiment will be described mainly with respect to the parts different from the first embodiment. It should be noted that the parts common to the first embodiment are denoted by the same names and the same reference numerals.

[0345] like Fig.13 As shown, the structure of a part of the damping force generating mechanism 10C of the shock absorber 1C including the damping force generating mechanism 10C of the fourth embodiment is different from that of the damping force generating mechanism 10. The structure between the disk 53 and the second damping valve 60 in the axial direction of the piston rod 21 of the damping force generating mechanism 10C is different from that of the damping force generating mechanism 10.

[0346] The damping force generating mechanism 10C has, on the side of the disk 53 on the axial direction of the piston rod 21 opposite to the first damping valve 52, a disk 450, a disk 451, a disk 452, an elastic disk 453, an opening and closing disk 57C, and a pilot housing 58C (force generating component) in order from the side of the disk 53 on the axial direction of the piston rod 21.

[0347] The disks 450 to 452, the elastic disk 453, the opening and closing disk 57C, and the pilot housing 58C are all made of metal. The disks 450 to 452 and the opening and closing disk 57C are all circular flat plates with holes of a constant thickness. The disks 450 to 452, the elastic disk 453, and the opening and closing disk 57C are formed by stamping. The elastic disk 453 is in the shape of a circular plate. The pilot housing 58C is in the shape of a circular ring. The disks 450 to 452, the elastic disk 453, the opening and closing disk 57C, and the pilot housing 58C are all fitted with the mounting shaft portion 28 of the piston rod 21 on the inner side.

[0348] The pilot housing 58C is in the shape of a bottomed cylinder. The pilot housing 58C is integrally formed by sintering so as to be seamless as a whole. The pilot housing 58C has a bottom 65C and a cylindrical portion 66C.

[0349] The bottom portion 65C is in the shape of a disk having a hole, and the mounting shaft portion 28 of the piston rod 21 is fitted on the inner peripheral side thereof.

[0350] The cylindrical portion 66C extends from one axial end side of the outer peripheral portion of the bottom portion 65C along the axial direction of the bottom portion 65C. The cylindrical portion 66C has a cylindrical shape.

[0351] The pilot housing 58C has an opening portion 67 on the side opposite to the bottom portion 65C in the axial direction of the cylindrical portion 66C.

[0352] The bottom portion 65C includes a bottom body portion 71C and the inner seat portion 77 and the outer seat portion 78 similar to those described above.

[0353] The bottom body portion 71C is in the shape of a disk having a hole. The cylindrical portion 66C extends from the axial side of the bottom body portion 71C opposite to the inner seat portion 77 and the outer seat portion 78 along the axial direction of the bottom body portion 71C.

[0354] The bottom body portion 71C is provided with a seal groove 68C at a radially intermediate position of the bottom body portion 71C. The seal groove 68C is recessed from an end surface of the bottom body portion 71C on the opposite side of the inner seat portion 77 and the outer seat portion 78 in the axial direction toward the inner seat portion 77 and the outer seat portion 78 in the axial direction of the bottom body portion 71C.

[0355] The bottom body portion 71C has a bottom surface of the sealing groove 68C. Fig.14The inner passage holes 80C and 81C shown in the figure. The inner passage holes 80C and 81C penetrate the bottom body portion 71C at the position of the sealing groove 68C. The inner passage hole 80C is located on the inner side of the inner passage hole 81C in the radial direction of the pilot housing 58C. The inner passage hole 80C is located at the inner end position of the bottom surface of the sealing groove 68C in the radial direction of the pilot housing 58C. The inner passage hole 81C is located at the outer end position of the bottom surface of the sealing groove 68C in the radial direction of the pilot housing 58C. The pilot housing 58C is provided with a plurality of inner passage holes 80C and 81C (specifically, three each). The inner passage holes 80C and the inner passage holes 81C are alternately arranged at equal intervals in the circumferential direction of the pilot housing 58C.

[0356] The pilot housing 58C has an outer passage hole 83C formed on the outer side of the bottom body 71C in the radial direction of the bottom body 71C relative to the seal groove 68C. The outer passage hole 83C penetrates the bottom body 71C in the axial direction of the bottom body 71C. The pilot housing 58C has a plurality of (specifically, six) outer passage holes 83C arranged at equal intervals in the circumferential direction of the pilot housing 58C. The outer passage holes 83C are arranged so that the positions in the circumferential direction of the pilot housing 58C coincide with either the inner passage hole 80C or the inner passage hole 81C.

[0357] The seat forming portions 91 (see Figure 3 ) and the seat forming portion 91, the inner passage holes 80C, 81C and the outer passage hole 83C are provided. Therefore, the inner passage holes 80C, 81C and the outer passage hole 83C are provided outside the outer seat portion 78. The inner passage holes 80C, 81C and the outer passage hole 83C are not provided in the passage recess 92 (refer to Figure 3 )Inner opening.

[0358] A passage groove 468 is formed on the axially opposite side of the bottom body portion 71C from the inner seat portion 77, extending from the seal groove 68C to the radially inner side of the bottom body portion 71C. Fig.13 As shown, the seal groove 68C is communicated with the rod-side passage 191 of the piston rod 21.

[0359] The damping force generating mechanism 10C has a partitioning component 111C (movable mechanism) in the sealing groove 68C. The partitioning component 111C is annular as a whole, and is an O-ring whose cross-section on the plane including the central axis of the annular ring is circular. The partitioning component 111C is made of an elastic material with sealing properties, specifically, rubber. The partitioning component 111C is embedded in the sealing groove 68C. The partitioning component 111C seals the gap between the sealing portion 112C located on its inner periphery and the radially inner wall of the sealing groove 68C. The partitioning component 111C seals the gap between the sealing portion 113C located on its outer periphery and the radially outer wall of the sealing groove 68C.

[0360] The outer diameter of the disk 450 is larger than the outer diameter of the disk 53 and smaller than the minimum inner diameter of the sealing member 132 .

[0361] The disk 451 has an outer diameter equal to that of the disk 450. A notch 471 is formed on the outer periphery of the disk 451. A plurality of notches 471 are provided on the disk 451 at equal intervals in the circumferential direction thereof.

[0362] The disk 452 has an outer diameter smaller than that of the disk 451 .

[0363] The elastic disk 453 has an outer diameter larger than the outer diameter of the disk 452 .

[0364] The elastic disk 453 has a base portion 481 and a protruding portion 482 .

[0365] The substrate 481 is in the shape of a circular flat plate with a constant thickness and a hole before the elastic disc 453 is assembled to the damping force generating mechanism 10C. The protrusion 482 protrudes to one side along the axial direction of the substrate 481 from the middle position of the outer peripheral side in the radial direction of the substrate 481. The protrusion 482 is annular and extends along the circumferential direction of the substrate 481.

[0366] The base plate 481 is provided with a passage hole 485 at a position radially outward of the disk 452. The passage hole 485 penetrates the base plate 481 radially inward of the protrusion 482 in the axial direction of the base plate 481. A plurality of passage holes 485 are provided at equal intervals in the circumferential direction of the base plate 481.

[0367] The opening and closing disc 57C has an outer diameter larger than the outer diameter of the protrusion 482 of the elastic disc 453. The opening and closing disc 57C extends to a position on the outside of the outer passage hole 83C in the radial direction of the pilot housing 58C. The opening and closing disc 57C abuts against the bottom body 71C of the pilot housing 58C in a surface contact manner, thereby blocking the sealing groove 68C and the outer passage hole 83C. The opening and closing disc 57C covers the entirety of the sealing groove 68C and the outer passage hole 83C. The opening and closing disc 57C opens the passage in the outer passage hole 83C by leaving the seat from the bottom body 71C.

[0368] When assembled in the damping force generating mechanism 10C, the elastic disk 453 contacts the opening and closing disk 57C at the protrusion 482. Thus, the elastic disk 453 elastically deforms in a tapered shape such that the base plate portion 481 moves axially farther away from the closing disk 57C as it moves radially outward.

[0369] The passage hole 491 is formed in the opening and closing disc 57C so that the position in the radial direction coincides with the passage hole 485 of the elastic disc 453. The passage hole 491 penetrates the opening and closing disc 57C in the axial direction of the opening and closing disc 57C. The passage hole 491 extends in an arc shape in the circumferential direction of the opening and closing disc 57C. The passage hole 491 is always connected to the passage hole 485 of the elastic disc 453. The passage hole 491 is located on the inner side of the sealing groove 68C of the pilot housing 58C in the radial direction of the opening and closing disc 57C. The passage hole 491 is always connected to the passage groove 468 of the pilot housing 58C.

[0370] The sealing parts 112C and 113C of the partition member 111C are simultaneously pressed against the radially inner and radially outer wall surfaces of the sealing groove 68C. As a result, the portion surrounded by the pilot housing 58C, the first damping valve 52, the discs 53, 450 to 452, the elastic disc 453, the opening and closing disc 57C, and the partition member 111C becomes the back pressure chamber 171C. The back pressure chamber 171C is always connected to the passage in the passage groove 30 of the piston rod 21 via the passage holes 485 and 491 and the passage in the passage groove 468.

[0371] Furthermore, the partition member 111C forms a variable chamber 172C between the bottom surface side of the seal groove 68C and the partition member 111C. The variable chamber 172C is always in communication with the lower chamber 20 via the passages in the inner passage holes 80C and 81C.

[0372] The bottomed cylindrical pilot housing 58C forms a back pressure chamber 171C inside thereof by the first damping valve 52, the disks 53, 450 to 452, the opening and closing disk 57C and the partition member 111C. The partition member 111C is provided in the pilot housing 58C and partitions the pilot housing 58C into the back pressure chamber 171C and the variable chamber 172C.

[0373] Disk 50 (refer to Figure 2 ) of the incision 121 (refer to Figure 2 ) in the passage groove 30 of the piston rod 21, the passage in the passage groove 468, and the passages in the passage holes 485 and 491 constitute the passage 43 from the piston side (refer to Figure 2 ) is branched into a back pressure chamber introduction passage 176C. The back pressure chamber introduction passage 176C is connected to the piston side passage 43 (see Figure 2 ) part so that the upper chamber 19 (refer to Figure 2 ) is connected to the back pressure chamber 171C. The back pressure chamber introduction passage 176C is connected from the upper chamber 19 (refer to Figure 2 ) through the piston side passage 43 (refer to Figure 2 ) introduces a portion of the oil L into the back pressure chamber 171C.

[0374] The passages in the inner passage holes 80C and 81C provided in the bottom 65C of the pilot housing 58C and the passage in the seal groove 68C constitute a first passage 173C extending and connecting the back pressure chamber 171C and the lower chamber 20. A partition member 111C having seal portions 112C and 113C for sealing the first passage 173C by an elastic member is movably provided in the first passage 173C.

[0375] The back pressure chamber 171C causes the internal pressure to flow along the piston 18 (see Figure 2 ) direction even if the disk 131 is seated on the valve seat portion 47 (refer to Figure 2 ) acts on the first damping valve 52 in the valve closing direction. The pilot housing 58C is a bottomed cylindrical shape and forms a back pressure chamber 171C that causes the first damping valve 52 disposed on the opening 67 side to generate a force in the valve closing direction.

[0376] The second passage 180C is formed in the outer passage hole 83C of the pilot housing 58C. The opening and closing disc 57C is provided between the second passage 180C and the back pressure chamber 171C in an openable and closable manner. The second passage 180C in the outer passage hole 83C is provided in parallel with the first passage 173C. The second passage 180C is arranged on the outer peripheral side of the first passage 173C in the pilot housing 58C. The opening and closing disc 57C cuts off the flow of the oil L between the back pressure chamber 171C and the second passage 180C and the lower chamber 20 in a state where the opening and closing disc 57C is in contact with the bottom body 71C of the pilot housing 58C in a surface contact manner. In addition, the opening and closing disc 57C allows the flow of the oil L between the back pressure chamber 171C and the second passage 180C and the lower chamber 20 in a state where the opening and closing disc 57C is separated from the bottom body 71C of the pilot housing 58C.

[0377] Here, the opening and closing disc 57C and the elastic disc 453 allow the flow of the oil L from the lower chamber 20 and the second passage 180C to the back pressure chamber 171C when the pressure on the second passage 180C and the lower chamber 20 side is higher than the pressure on the back pressure chamber 171C side by a predetermined value or more. The opening and closing disc 57C and the elastic disc 453 restrict the flow of the oil L from the back pressure chamber 171C to the lower chamber 20 via the second passage 180C when the pressure on the back pressure chamber 171C side is higher than the pressure on the second passage 180C and the lower chamber 20 side.

[0378] The opening and closing disc 57C, the elastic disc 453, and the portion of the bottom body 71C of the pilot housing 58C on the side of the opening and closing disc 57C in the axial direction constitute a communication mechanism 181C. One side of the second passage 180C can communicate with the back pressure chamber 171C. The communication mechanism 181C is located on the one side of the second passage 180C, and can communicate with the other side of the second passage 180C, that is, the lower chamber 20 side, only when the lower chamber 20 is on the upstream side. In other words, the communication mechanism 181C cannot communicate with the other side of the second passage 180C, that is, the lower chamber 20 side, when the lower chamber 20 is on the downstream side. The communication mechanism 181C restricts the flow of the oil L in one direction from the back pressure chamber 171C side to the second passage 180C side between the back pressure chamber 171C and the second passage 180C. On the other hand, the communication mechanism 181C allows the flow of the oil L in the other direction from the second passage 180C side to the back pressure chamber 171C side. The communication mechanism 181C is a one-way valve, and the opening and closing disc 57C is a valve member of the communication mechanism 181C.

[0379] The communication mechanism 181C restricts the flow of electricity from the upper chamber 19 (see Figure 2 )、Piston side passage 43 (refer to Figure 2 ), the back pressure chamber introduction passage 176C, and the flow of the oil L from the back pressure chamber 171C to the second passage 180C and the lower chamber 20. The communication mechanism 181C allows the flow of the oil L from the lower chamber 20 and the second passage 180C to the back pressure chamber 171C, the back pressure chamber introduction passage 176C, the piston side passage 43 (see Figure 2 ) and the upper chamber 19 (refer to Figure 2 ) of the oil L.

[0380] The pilot housing 58C and the partition member 111C constitute the response piston 18 (see Figure 2 ) of the reciprocating motion frequency. The dividing member 111C of the frequency response mechanism 211C is configured to vary the damping force according to the frequency of the reciprocating motion of the piston 18 (see Figure 2 ) to move and deform at the frequency of the reciprocating motion, so that the upper chamber 19 (reference Figure 2) and the capacity of the variable chamber 172C that is always in communication with the lower chamber 20. The frequency response mechanism 211C has a partition member 111C that is movably provided in the first passage 173C. The frequency response mechanism 211C makes the force acting on the first damping valve 52 based on the back pressure chamber 171C variable.

[0381] In the stretching stroke, the pressure difference between the back pressure chamber 171C and the lower chamber 20 is higher on the back pressure chamber 171C side than on the lower chamber 20 side. Then, the partition member 111C maintains the sealed state with the sealing groove 68C due to the pressure of the back pressure chamber 171C, and moves toward the bottom surface side of the sealing groove 68C and abuts against the bottom surface to be compressed and deformed. As a result, the volume of the back pressure chamber 171C is expanded.

[0382] In the contraction stroke, the lower chamber 20 side is at a higher pressure than the back pressure chamber 171C side. Therefore, if the pressure difference between the lower chamber 20 side and the back pressure chamber 171C side is lower than the specified value, the dividing member 111C maintains the sealing state with the sealing groove 68C due to the pressure on the lower chamber 20 side, and moves toward the opening and closing disc 57C side and abuts against the opening and closing disc 57C to be compressed and deformed. As a result, the volume of the variable chamber 172C is expanded. In addition, in the contraction stroke, when the lower chamber 20 side becomes a higher pressure than the back pressure chamber 171C side by a specified value or more, the connecting mechanism 181C opens the valve to allow the oil L to flow from the lower chamber 20 to the back pressure chamber 171C.

[0383] Next, the operation of the shock absorber 1C including the damping force generating mechanism 10C will be described.

[0384] {Low frequency and ultra-low speed range of stretching stroke x1}

[0385] In the low frequency and ultra-low speed range x1, the first valve mechanism 41 and the second valve mechanism 201 do not open. Figure 2 ) through the piston side passage 43 (refer to Figure 2 ) and the back pressure chamber introduction passage 176C flow into the back pressure chamber 171C. Then, the partition member 111C of the frequency response mechanism 211C moves toward the bottom surface side of the sealing groove 68C and abuts against the bottom surface to be compressed and deformed. In this low-frequency and ultra-low-speed range x1, the partition member 111C of the frequency response mechanism 211C moves toward the bottom surface side of the sealing groove 68C to the limit and deforms, and then becomes difficult to deform. In addition, in the first valve mechanism 41, 42 (refer to Figure 2 ) and the second valve mechanism 201 do not have a fixed damping hole that always connects the upper chamber 19 and the lower chamber 20. As a result, in the low-frequency and ultra-low-speed range x1, the increase rate of the damping force relative to the increase in piston speed becomes high.

[0386] {Low frequency and low speed range of stretching stroke x2}

[0387] In the low frequency and low speed range x2, from the upper chamber 19 (refer to Figure 2 ) causes the dividing member 111C of the frequency response mechanism 211C to move and deform greatly toward the bottom surface side of the sealing groove 68C, as in the low-frequency ultra-low-speed range x1. Then, the oil L in the piston side passage 43 (refer to Figure 2 ) and the back pressure chamber introduction passage 176C from the upper chamber 19 (refer to Figure 2 ) becomes difficult to be introduced into the back pressure chamber 171C. In the low frequency and low speed range x2, the pressure of the back pressure chamber 171C is higher than that in the low frequency and ultra-low speed range x1. Therefore, in the low frequency and low speed range x2, the pressure from the upper chamber 19 (refer to Figure 2 ) is released from the piston side passage 43 (refer to Figure 2 ), the back pressure chamber introduction passage 176C and the rod side passage 191 flow to the lower chamber 20. As a result, in the low frequency and low speed range x2, the rate of increase of the damping force relative to the increase of the piston speed becomes lower than that in the low frequency and ultra-low speed range x1. In this low frequency and low speed range x2, the dividing member 111C of the frequency response mechanism 211C moves to the limit and deforms, so the pressure of the back pressure chamber 171C becomes high pressure. Therefore, the first damping valve 52 of the first valve mechanism 41 is restricted from opening due to the large force from the back pressure chamber 171C.

[0388] {Low frequency, medium and high speed range of stretching stroke x3}

[0389] In the low-frequency, medium-speed and high-speed range x3, from the upper chamber 19 (refer to Figure 2 ) is similar to the low-frequency and low-speed range x2, and the oil L is released from the piston side passage 43 (see Figure 2 ), a portion of the back pressure chamber introduction passage 176C, and the rod side passage 191 flow into the lower chamber 20. In the low frequency and high speed range x3, the oil L flows from the rod side passage 191 to the lower chamber 20, thereby suppressing the oil L from flowing into the lower chamber 20 through the piston side passage 43 (refer to Figure 2 ) and the oil L introduced into the back pressure chamber 171C by the back pressure chamber introduction passage 176C. Figure 2 ) increases the force in the valve opening direction applied to the first valve mechanism 41, so the force from the upper chamber 19 (refer to Figure 2 ) through the piston side passage 43 (refer to Figure 2) and opens the first damping valve 52 of the first valve mechanism 41 to flow into the lower chamber 20. As a result, in the low-frequency, medium-speed, and high-speed range x3, the rate of increase of the damping force relative to the increase in piston speed becomes lower than that in the low-frequency, low-speed range x2.

[0390] {High frequency ultra-low speed range of stretching stroke x4}

[0391] In the high frequency ultra-low speed range x4, the first valve mechanism 41 and the second valve mechanism 201 do not open the valve. Figure 2 ) is passed through the piston side passage 43 (refer to Figure 2 ) and the back pressure chamber introduction passage 176C flow into the back pressure chamber 171C. Then, the partition member 111C of the frequency response mechanism 211C moves toward the bottom surface side of the seal groove 68C and deforms. In this high frequency ultra-low speed range x4, the piston frequency is high frequency and the piston 18 (refer to Figure 2 ) has a smaller stroke. Therefore, the oil L introduced from the upper chamber 19 to the back pressure chamber 171C becomes less than the low frequency ultra-low speed range x1. Therefore, the dividing member 111C of the frequency response mechanism 211C is not deformed to the limit and is easily deformed. As a result, the movement and deformation of the dividing member 111C can absorb the oil L from the upper chamber 19 (refer to Figure 2 ) The oil L introduced into the back pressure chamber 171C. Therefore, in the high-frequency ultra-low speed range x4, although the increase rate of the damping force relative to the increase in piston speed becomes higher, the damping force at the same piston speed becomes lower than that in the low-frequency ultra-low speed range x1, becoming a soft characteristic.

[0392] {High frequency, low, medium and high speed range of stretching stroke x5}

[0393] In the high-frequency, low-medium and high-speed range x5, from the upper chamber 19 (refer to Figure 2 ) causes the dividing component 111C of the frequency response mechanism 211C to move toward the bottom side of the sealing groove 68C and deform as in the high-frequency ultra-low speed range x4. In the high-frequency low-medium-high speed range x5, less oil L is introduced into the back pressure chamber 171C, so the pressure rise in the back pressure chamber 171C is suppressed by the deformation of the dividing component 111C. Therefore, the force from the back pressure chamber 171C on the first damping valve 52 of the first valve mechanism 41 becomes smaller, and the first damping valve 52 becomes easier to open. Therefore, the pressure from the upper chamber 19 (refer to Figure 2 ) through the piston side passage 43 (refer to Figure 2) and opens the first damping valve 52 of the first valve mechanism 41 to flow to the lower chamber 20. As a result, in the high-frequency low-medium-high speed range x5, the rate of increase of the damping force relative to the increase of the piston speed becomes lower than that in the high-frequency ultra-low speed range x4. In addition, in the high-frequency low-medium-high speed range x5, the damping force at the same piston speed becomes lower than that in the low-frequency low-speed range x2 and the low-frequency medium-high speed range x3, and becomes a soft characteristic. In this high-frequency low-medium-high speed range x5, the pressure rise in the back pressure chamber 171C is suppressed, so the second valve mechanism 201 maintains the closed valve state.

[0394] {Low frequency and ultra-low speed range of contraction stroke y1}

[0395] In the low frequency and ultra-low speed range y1, the first valve mechanism 42 (refer to Figure 2 ) and the connecting mechanism 181C do not open the valve. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172C through the passages in the inner passage holes 80C and 81C in the first passage 173C. Then, the dividing member 111C of the frequency response mechanism 211C moves toward the opening and closing disk 57C and deforms. In this low-frequency and ultra-low-speed range y1, the piston frequency is low and the piston 18 (refer to Figure 2 ) is larger, so that at the beginning of the stroke, more oil L is introduced from the lower chamber 20 to the variable chamber 172C. Therefore, the partition member 111C of the frequency response mechanism 211C moves to the side of the opening and closing disc 57C until it is close to the limit and deforms, and becomes difficult to deform. Figure 2 ) and the second valve mechanism 201 do not have a fixed damping hole that always connects the lower chamber 20 and the upper chamber 19. As a result, in the low-frequency ultra-low-speed range y1, the increase rate of the damping force relative to the increase in piston speed becomes high, becoming a hard characteristic.

[0396] {Low frequency and low speed range of contraction stroke y2}

[0397] In the low-frequency and low-speed range y2, the oil L from the lower chamber 20 moves the dividing member 111C to the side of the opening and closing disc 57C until it is close to the limit and deforms, and then opens the connecting mechanism 181C to flow from the second passage 180C through the back pressure chamber 171C, the back pressure chamber introduction passage 176C and the piston side passage 43 (refer to Figure 2 ) to the upper chamber 19 (refer to Figure 2 As a result, in the low-frequency and low-speed range y2, the rate of increase of the damping force relative to the increase of the piston speed becomes lower than that in the low-frequency and ultra-low-speed range y1.

[0398] {Low frequency, medium and high speed range of contraction stroke y3}

[0399] In the low-frequency and medium-speed range y3, as in the low-frequency and low-speed range y2, the oil L from the lower chamber 20 is opened by opening the communication mechanism 181C from the second passage 180C through the back pressure chamber 171C, the back pressure chamber introduction passage 176C, and the piston side passage 43 (see Figure 2 ) to the upper chamber 19 (refer to Figure 2 ) flows. In the low-frequency, low-medium-high-speed range y2, in addition, the oil L from the lower chamber 20 flows through the piston side passage 44 (refer to Figure 2 ) and the first valve mechanism 42 (refer to Figure 2 ) of the first damping valve 231 (refer to Figure 2 ) is opened and upward chamber 19 (refer to Figure 2 As a result, in the low-frequency, medium-speed, and high-speed range y3, the rate of increase of the damping force relative to the increase in the piston speed becomes lower than that in the low-frequency, low-speed range y2.

[0400] {High frequency ultra-low speed range of contraction stroke y4}

[0401] In the high-frequency ultra-low-speed range y4, the first valve mechanism 42 and the connecting mechanism 181C do not open the valves. In addition, the oil L from the lower chamber 20 is introduced into the variable chamber 172C via the passages in the inner passage holes 80C and 81C in the first passage 173C. As a result, the dividing component 111C of the frequency response mechanism 211C is deformed toward the side of the opening and closing disc 57C. In this high-frequency ultra-low-speed range y4, the piston frequency is high frequency and the stroke of the piston 18 is small, so the oil L introduced from the lower chamber 20 to the variable chamber 172C becomes less than that in the low-frequency ultra-low-speed range y1. Therefore, the dividing component 111C of the frequency response mechanism 211C is not deformed to the limit and is easy to move and deform. As a result, the oil L introduced from the lower chamber 20 to the variable chamber 172C can be absorbed by the movement and deformation of the dividing component 111C. Therefore, in the high-frequency ultra-low-speed range y4, the damping force at the same piston speed has a softer characteristic than that in the low-frequency ultra-low-speed range y1.

[0402] {High frequency and low speed range of contraction stroke y5}

[0403] In the high-frequency and low-speed range y5, the oil L from the lower chamber 20 is discharged from the second passage 180C through the back pressure chamber 171C, the back pressure chamber introduction passage 176C, and the piston side passage 43 (see Figure 2 ) to the upper chamber 19 (refer to Figure 2 ) flow. In the high-frequency and low-speed range y5, the rate of increase of the damping force relative to the increase of the piston speed becomes lower than that in the high-frequency and ultra-low-speed range y4. In addition, in the high-frequency and low-speed range y5, the damping force at the same piston speed becomes lower and softer than that in the low-frequency and low-speed range y2.

[0404] {High frequency, medium and high speed range of contraction stroke y6}

[0405] In the high-frequency and medium-speed range y6, as in the high-frequency and low-speed range y5, the oil L from the lower chamber 20 is opened by opening the communication mechanism 181C from the second passage 180C through the back pressure chamber 171C, the back pressure chamber introduction passage 176C, and the piston side passage 43 (see Figure 2 ) to the upper chamber 19 (refer to Figure 2 In the high-frequency and high-speed range y6, in addition, the oil L from the lower chamber 20 flows through the piston side passage 44 (refer to Figure 2 ) and the first valve mechanism 42 (refer to Figure 2 ) of the first damping valve 231 (refer to Figure 2 ) is opened and upward chamber 19 (refer to Figure 2 ) flow. As a result, in the high-frequency, medium-high speed range y6, the rate of increase of the damping force relative to the increase of the piston speed becomes lower than that in the high-frequency, low-speed range y5. Moreover, in the high-frequency, medium-high speed range y6, the damping force at the same piston speed becomes lower and softer than that in the low-frequency, medium-high speed range y3.

[0406] The damping force generating mechanism 10C of the fourth embodiment includes a pilot housing 58C, a frequency response mechanism 211C, a second passage 180C, and a communication mechanism 181C. The pilot housing 58C is a bottomed cylindrical shape and is formed with a back pressure chamber 171C that generates a force in the valve closing direction for the first damping valve 52 disposed on the opening 67 side. The frequency response mechanism 211C is provided with a partition member 111C having sealing portions 112C and 113C that seal the first passage 173C with an elastic member in a movably manner in a first passage 173C that is provided at the bottom 65C of the pilot housing 58C and connects the back pressure chamber 171C with the lower chamber 20, so that the force in the valve closing direction for the first damping valve 52 is variable. The second passage 180C is provided in parallel with the first passage 173C, and one side can be communicated with the back pressure chamber 171C. The communication mechanism 181C is located on the one side of the second passage 180C, and can communicate with the other side of the second passage 180C only when the lower chamber 20 is located on the upstream side.

[0407] As described above, the damping force generating mechanism 10C is provided with the first passage 173C which connects and extends the back pressure chamber 171C and the lower chamber 20 at the bottom 65C of the pilot housing 58C forming the back pressure chamber 171C. In addition, the damping force generating mechanism 10C is provided with the frequency response mechanism 211C in the first passage 173C in a manner that allows the partition member 111C which seals the first passage 173C with the sealing parts 112C and 113C to be movably provided, so that the force acting on the closing direction of the first damping valve 52 is variable. Therefore, although the damping force generating mechanism 10C has the frequency response mechanism 211C, it is possible to suppress the size increase.

[0408] Furthermore, the damping force generating mechanism 10C is provided with a connecting mechanism 181C, so when the stroke is reversed from the contraction stroke to the extension stroke, the connecting mechanism 181C opens the valve, and the oil L is introduced from the lower chamber 20, which is at a higher pressure than the upper chamber 19 in the contraction stroke, to the back pressure chamber 171C via the second passage 180C, so that the pressure of the back pressure chamber 171C can be quickly increased. As a result, the closed valve state of the first damping valve 52, which is urged in the valve closing direction by the pressure of the back pressure chamber 171C, is stabilized. Thus, the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke can be suppressed.

[0409] Furthermore, the damping force generating mechanism 10C arranges the second passage 180C opened and closed by the communication mechanism 181C at the outer peripheral side of the bottom 65C relative to the first passage 173C. Therefore, the damping force generating mechanism 10C can cover the entire opening of the first passage 173C on the side of the opening and closing disc 57C by the communication mechanism 181C. Therefore, it is possible to suppress the partitioning member 111C provided in the first passage 173C from entering the gap between the opening and closing disc 57C and the opening of the first passage 173C. Therefore, it is possible to suppress the degradation of the durability of the partitioning member 111C.

[0410] Furthermore, since the damping force generating mechanism 10C uses an O-ring as the partitioning member 111C having the sealing portions 112C and 113C that seal the first passage 173C via an elastic member, the compression deformation is large. Thus, the effect of suppressing the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke by providing the connecting mechanism 181C is high.

[0411] [Fifth Embodiment]

[0412] Then, mainly based on Fig.15 The fifth embodiment will be described with the focus on the parts that are different from the third embodiment. It should be noted that the parts that are common to the third embodiment are represented by the same names and the same symbols.

[0413] like Fig.15 As shown, the shock absorber 1D including the damping force generating mechanism 10D of the fifth embodiment has a damping force generating mechanism 10D of which a part has a different structure from the damping force generating mechanism 10B.

[0414] The damping force generating mechanism 10D is not provided with the opening and closing disk 57B. In addition, the damping force generating mechanism 10D includes a pilot housing 58D which is partially different from the pilot housing 58B instead of the pilot housing 58B. In addition, the damping force generating mechanism 10D includes a partitioning member 111D which is partially different from the partitioning member 111B instead of the partitioning member 111B.

[0415] The pilot housing 58D includes a housing member 360D that is partially different from the housing member 360 instead of the housing member 360. The housing member 360D includes a bottom 365D that is partially different from the bottom 365 instead of the bottom 365. The bottom 365D includes a protrusion 501 that protrudes from the bottom body portion 371 to the same side as the other side seat portion 373 in the axial direction of the bottom body portion 371. The protrusion 501 is provided between the other side seat portion 373 and the cylindrical portion 366 in the radial direction of the bottom body portion 371. A plurality of protrusions 501 are provided at equal intervals in the circumferential direction of the bottom body portion 371. The pilot housing 58D includes a bottom 65D that is different from the bottom 65B in that it includes the protrusion 501.

[0416] The partition member 111D includes a disk 421D that is partially different from the disk 421 instead of the disk 421. Also, the partition member 111D includes a gasket 422D that is partially different from the gasket 422 instead of the gasket 422.

[0417] The disk 421D is different from the disk 421 in that the via hole 425 is not formed.

[0418] The gasket 422D is made of an elastic material with sealing properties, specifically, rubber. The gasket 422D is annular. The gasket 422D is fixed to the outer peripheral side of the disk 421D. The gasket 422D protrudes from the disk 421D to one side in the axial direction of the disk 421D. The sealing portion 112D of the outer peripheral portion of the gasket 422D expands in the radial direction of the disk 421D as it moves away from the disk 421D in the axial direction of the disk 421D. The inner peripheral portion of the gasket 422D expands in the radial direction of the disk 421D as it moves away from the disk 421D in the axial direction of the disk 421D.

[0419] The gasket 422D is fitted over the entire circumference of the inner circumferential surface of the cylindrical portion 366 of the housing member 360D. At that time, the gasket 422D contacts the inner circumferential surface of the cylindrical portion 366 at the sealing portion 112D of the outer circumferential portion thereof. The gasket 422D is axially slidable relative to the inner circumferential surface of the cylindrical portion 366. The gasket 422D seals the gap between the partition member 111D and the cylindrical portion 366. The protrusion 501 of the pilot housing 58D is arranged on the inner side of the gasket 422D in the radial direction of the disk 421D.

[0420] The sealing portion 112D of the gasket 422D of the partition member 111D is pressed against the inner peripheral surface of the cylindrical portion 366 of the housing member 360D over the entire circumference. Fig.10 )、Pressing member 361 (refer to Fig.10 )、Sealing member 402 (refer to Fig.10), the portion surrounded by the casing member 360D and the partition member 111D forms a back pressure chamber 171D. The back pressure chamber 171D is connected to the back pressure chamber introduction passage 176B (see Fig.10 ) and the rod side passage 341B (refer to Fig.10 ) connected.

[0421] The portion surrounded by the partition member 111D and the stopper member 411 becomes the variable chamber 172D. The variable chamber 172D is always connected to the lower chamber 20 via the passage in the passage hole 431 of the stopper member 411. The variable chamber 172D is always connected to the lower chamber 20 via the passage between the stopper member 411 and the cylindrical portion 366 of the housing member 360D.

[0422] The bottomed cylindrical pilot housing 58D has a back pressure chamber 171D formed therein by a partition member 111D. The partition member 111D is provided in the pilot housing 58D and partitions the interior of the pilot housing 58D into the back pressure chamber 171D and a variable chamber 172D.

[0423] The passage between the outer peripheral portion of the stopper member 411 and the cylindrical portion 366 of the housing member 360D, the passage in the passage hole 431 of the stopper member 411, the variable chamber 172D, the passage between the sealing portion 112D of the gasket 422D and the cylindrical portion 366 constitutes a first passage 173D extending and connecting the back pressure chamber 171D and the lower chamber 20. The partition member 111D having the sealing portion 112D for sealing the first passage 173D by an elastic member is movably provided in the first passage 173D.

[0424] The back pressure chamber 171D causes the internal pressure to flow along the seat forming member 351 (see Fig.10 ) direction even if the first damping valve 52B is seated on the valve seat portion 356 (refer to Fig.10 ) in the valve closing direction acts on the first damping valve 52B (refer to Fig.10 The pilot housing 58D is a bottomed cylindrical shape and is formed so that the opening 67B (see Fig.10 ) side, the first damping valve 52B configured to generate a back pressure chamber 171D with a force in the valve closing direction.

[0425] The sealing portion 112D of the gasket 422D of the partition member 111D is provided between the first passage 173D and the back pressure chamber 171D in an openable and closable manner. The sealing portion 112D of the gasket 422D cuts off the flow of the oil L between the back pressure chamber 171D, the first passage 173D, and the lower chamber 20 while being in contact with the inner peripheral surface of the cylindrical portion 366 of the housing member 360D over the entire circumference. Furthermore, the sealing portion 112D of the gasket 422D allows the flow of the oil L between the back pressure chamber 171D, the first passage 173D, and the lower chamber 20 while being separated from the inner peripheral surface of the cylindrical portion 366 of the housing member 360D.

[0426] Here, when the pressure on the lower chamber 20 side is higher than the pressure on the back pressure chamber 171D side by a predetermined value or more, the sealing portion 112D of the gasket 422D is separated from the cylindrical portion 366, and the oil L from the lower chamber 20 to the back pressure chamber 171D via the first passage 173D is allowed to flow. That is, when the pressure on the lower chamber 20 side is higher than the pressure on the back pressure chamber 171D side by a predetermined value or more, although the partition member 111D is trying to move toward the bottom body portion 371 side in the axial direction, the protrusion 501 of the housing member 360D abuts against the disk 421D, thereby suppressing the movement of the disk 421D toward the bottom body portion 371 side. As a result, the partition member 111D is well separated from the inner peripheral surface of the cylindrical portion 366 by the pressure difference between the variable chamber 172D and the back pressure chamber 171D, and the oil L flows from the lower chamber 20 to the back pressure chamber 171D via the first passage 173D. When the pressure on the back pressure chamber 171D side is higher than the pressure on the lower chamber 20 side, the seal portion 112D of the gasket 422D contacts the cylindrical portion 366 to restrict the flow of the oil L from the back pressure chamber 171D to the lower chamber 20 via the first passage 173D.

[0427] The gasket 422D and the cylindrical portion 366 of the housing member 360D constitute a communication mechanism 181D. One side of the first passage 173D can communicate with the back pressure chamber 171D. The communication mechanism 181D is located on the one side of the first passage 173D, and can communicate with the other side of the first passage 173D, that is, the lower chamber 20 side, only when the lower chamber 20 is on the upstream side. In other words, the communication mechanism 181D cannot communicate with the other side of the first passage 173D, that is, the lower chamber 20 side, when the lower chamber 20 is on the downstream side. The communication mechanism 181D restricts the flow of the oil L in one direction from the back pressure chamber 171D side to the variable chamber 172D side between the back pressure chamber 171D and the variable chamber 172D. On the other hand, the communication mechanism 181D allows the flow of the oil L in the other direction from the variable chamber 172D side to the back pressure chamber 171D side. The communication mechanism 181D is a one-way valve, and the partition member 111D is a valve member of the communication mechanism 181D.

[0428] The first passage 173D is provided to connect the back pressure chamber 171D and the lower chamber 20, and is provided with a partitioning member 111D. The first passage 173D provided with the partitioning member 111D also serves as a passage in which one side can communicate with the back pressure chamber 171D and a communication mechanism 181D is provided, and the communication mechanism 181D is located on the one side and can communicate with the other side only when the lower chamber 20 side is on the upstream side.

[0429] The communication mechanism 181D restricts the flow of electricity from the upper chamber 19 (see Fig.10 )、Rod side passage 341B (refer to Fig.10 ), back pressure chamber introduction passage 176B (refer to Fig.10 ) and the back pressure chamber 171D to the lower chamber 20 via the first passage 173D. The communication mechanism 181D allows the oil L to flow from the lower chamber 20 to the back pressure chamber 171D and the back pressure chamber introduction passage 176B (see Fig.10 )、Rod side passage 341B (refer to Fig.10 ) and upper chamber 19 (refer to Fig.10 ) of the oil L.

[0430] The pilot housing 58D and the partition member 111D constitute a frequency response mechanism 211D that varies the damping force in response to the piston frequency. The partition member 111D of the frequency response mechanism 211D varies according to the piston 18A (see Fig.10 ) to move and deform at the frequency of the reciprocating motion, so that the upper chamber 19 (reference Fig.10 ) and the capacity of the variable chamber 172D that is always in communication with the lower chamber 20. The frequency response mechanism 211D includes a partition member 111D that is movably provided in the first passage 173D. The frequency response mechanism 211D causes the first damping valve 52B (see Fig.10 ) can be varied.

[0431] In the extension stroke, the pressure difference between the back pressure chamber 171D and the lower chamber 20 is higher on the back pressure chamber 171D side than on the lower chamber 20 side. Then, the partition member 111D is subjected to the pressure of the back pressure chamber 171D, and maintains the sealed state between the partition member 111D and the cylindrical portion 366, and deforms and moves toward the stopper member 411. As a result, the volume of the back pressure chamber 171D is expanded.

[0432] In the contraction stroke, the lower chamber 20 side is at a higher pressure than the back pressure chamber 171D side. Therefore, if the pressure difference between the lower chamber 20 side and the back pressure chamber 171D side is lower than a specified value, the dividing member 111D is subjected to the pressure on the lower chamber 20 side, and maintains the sealed state with the cylindrical portion 366, and deforms and moves to the side opposite to the stop member 411. As a result, the volume of the variable chamber 172D is expanded. In addition, in the contraction stroke, when the lower chamber 20 side becomes a higher pressure than the back pressure chamber 171D side by a specified value, the connecting mechanism 181D opens the valve to allow the oil L to flow from the lower chamber 20 to the back pressure chamber 171D.

[0433] The operation of the buffer 1D including the damping force generating mechanism 10D is almost the same as that of the buffer 1B, except that the connecting mechanism 181D that replaces the connecting mechanism 181B has a different valve opening point within the low-frequency and low-speed range y2, the low-frequency and medium-high speed range y3, the high-frequency and low-speed range y5, and the high-frequency and medium-high speed range y6 of the contraction stroke.

[0434] The damping force generating mechanism 10D of the fifth embodiment includes a pilot housing 58D, a frequency response mechanism 211D, a first passage 173D, and a communication mechanism 181D. The pilot housing 58D is a bottomed cylindrical shape and is formed so that the opening 67 (see Fig.10 ) side is configured with a first damping valve 52B (see Fig.10 The frequency response mechanism 211D is provided with a partition member 111D having a sealing portion 112D that seals the first passage 173D with an elastic member in a manner that allows movement of the first damping valve 52B (see Fig.10 ) in the valve closing direction. One side of the first passage 173D can communicate with the back pressure chamber 171D. The communication mechanism 181D is located on the one side of the first passage 173D and can communicate with the other side of the first passage 173D only when the lower chamber 20 is located on the upstream side.

[0435] As described above, the damping force generating mechanism 10D is provided with the first passage 173D that enables the back pressure chamber 171D to communicate with the lower chamber 20 at the bottom 65D of the pilot housing 58D forming the back pressure chamber 171D. The damping force generating mechanism 10D is provided with the frequency response mechanism 211D in the first passage 173D so as to be movably provided with the partition member 111D that seals the first passage 173D with the sealing portion 112D, thereby enabling the first damping valve 52B (see Fig.10 ) is variable. Therefore, although the damping force generating mechanism 10D has the frequency response mechanism 211D, it is possible to suppress enlargement.

[0436] Furthermore, the damping force generating mechanism 10D is provided with a connecting mechanism 181D, so when the stroke is reversed from the contraction stroke to the extension stroke, the connecting mechanism 181D opens, and the oil L is introduced from the lower chamber 20, which is at a higher pressure than the upper chamber 19 in the contraction stroke, to the back pressure chamber 171D via the first passage 173D, so that the pressure of the back pressure chamber 171D can be quickly increased. As a result, the first damping valve 52B (see FIG. 173D) which is urged in the valve closing direction by the pressure in the back pressure chamber 171D is closed. Fig.10 ) is in a stable closed valve state. Thus, it is possible to suppress the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke.

[0437] Furthermore, the first passage 173D provided with the partition member 111D of the damping force generating mechanism 10D also serves as a passage in which one side can communicate with the back pressure chamber 171D and a communication mechanism 181D is provided, and the communication mechanism 181D is located on the one side and can communicate with the other side only when the lower chamber 20 side is on the upstream side. Thus, the size of the damping force generating mechanism 10D can be further suppressed.

[0438] Furthermore, the communication mechanism 181D of the damping force generating mechanism 10D opens the gasket 422D of the partition member 111D that cuts off the communication between the back pressure chamber 171D and the variable chamber 172D when the pressure in the variable chamber 172D is higher than that in the back pressure chamber 171D, and introduces the oil L from the variable chamber 172D to the back pressure chamber 171D. Therefore, the structure of the communication mechanism 181D can be simplified.

[0439] [Sixth Embodiment]

[0440] Then, mainly based on Figure 16 to Figure 19 The sixth embodiment will be described with the focus on the parts that are different from the first embodiment. It should be noted that the parts that are common to the first embodiment are represented by the same names and the same symbols.

[0441] like Fig.16 As shown, the structure of a part of the damping force generating mechanism 10E of the shock absorber 1E including the damping force generating mechanism 10E of the sixth embodiment is different from that of the damping force generating mechanism 10. The structure between the disk 50 and the disk 61 of the damping force generating mechanism 10E in the axial direction of the piston rod 21 is different from that of the damping force generating mechanism 10.

[0442] The damping force generating mechanism 10E has, in order from the disc 50 side in the axial direction of the piston rod 21, a first damping valve 52E (first damping force generating member), an opening and closing disc 57E, a disc 53, a disc 54E, a plurality of (specifically, 6) discs 55 similar to the first embodiment, a pilot housing 58E (force generating member), a disc 511, a disc 512, and a plurality of (specifically, 4) discs 59 similar to the first embodiment. The discs 511, 512, and 59 constitute a second damping valve 60E.

[0443] The disk 54E is different from the disk 54 in that the cutout 141 is not formed.

[0444] The disks 511, 512, the opening and closing disk 57E and the pilot housing 58E are all made of metal. The disks 511, 512 and the opening and closing disk 57E are all circular flat plates with holes of constant thickness. The disks 511, 512 and the opening and closing disk 57E are formed by stamping. The pilot housing 58E is annular. The mounting shaft 28 of the piston rod 21 is embedded inside the disks 511, 512, the opening and closing disk 57E and the pilot housing 58E.

[0445] The pilot housing 58E is in the shape of a bottomed cylinder. The pilot housing 58E is integrally formed by sintering so as to be seamless as a whole. The pilot housing 58E is in the shape of a bottomed cylinder and has a bottom 65E instead of the bottom 65.

[0446] The bottom portion 65E is in the shape of a disk having a hole, and the mounting shaft portion 28 of the piston rod 21 is fitted on the inner circumference thereof. The pilot housing 58E has an opening 67 on the side opposite to the bottom portion 65E in the axial direction of the cylindrical portion 66 .

[0447] The bottom portion 65E has a bottom body portion 71E, an inner seat portion 77E, and a valve seat portion 78E.

[0448] The bottom body 71E is a disk with a hole, and the mounting shaft 28 of the piston rod 21 is fitted on the inner circumference thereof. The cylindrical portion 66 extends from one axial end side of the outer circumference of the bottom body 71E in the axial direction of the bottom body 71E.

[0449] The bottom body portion 71E is provided with a seal groove 68E at a middle position in the radial direction of the bottom body portion 71E. The seal groove 68E is annular and is formed on the inner side of the bottom body portion 71E in the radial direction of the bottom body portion 71E than the cylindrical portion 66. The seal groove 68E is recessed from the cylindrical portion 66 side in the axial direction of the bottom body portion 71E to the direction opposite to the cylindrical portion 66 in the axial direction of the bottom body portion 71E.

[0450] A passage hole 84E is formed on the bottom body portion 71E at the bottom surface of the seal groove 68E. The passage hole 84E penetrates the bottom body portion 71E at the position of the seal groove 68E. The passage hole 84E is located at the outer end position of the bottom surface of the seal groove 68E in the radial direction of the pilot housing 58E. In the pilot housing 58E, a plurality of passage holes 84E are provided at equal intervals in the circumferential direction of the pilot housing 58E.

[0451] A passage groove 468E extending radially inward from the seal groove 68E is formed on the axially cylindrical portion 66 side of the bottom body portion 71E. The passage groove 468E connects the passage in the seal groove 68E with the passage groove 30 of the piston rod 21.

[0452] The inner seat portion 77E is formed on the inner circumference side of the bottom body portion 71E. The inner seat portion 77E is annular. The inner seat portion 77E protrudes from the inner circumference side of the bottom body portion 71E along the axial direction of the bottom body portion 71E to the side opposite to the cylindrical portion 66. A passage groove 95E is formed on the inner seat portion 77E and penetrates the inner seat portion 77E in the radial direction. The passage in the passage groove 95E communicates with the passage in the passage groove 30 of the piston rod 21.

[0453] The valve seat portion 78E protrudes in the axial direction of the bottom body portion 71E toward the side opposite to the cylindrical portion 66. Fig.17 The valve seat portion 78E is provided so as to surround the inner seat portion 77E at the outer side in the radial direction of the bottom body portion 71E.

[0454] The damping force generating mechanism 10E is as follows Fig.16 As shown, a dividing component 111E (movable mechanism) is provided in the sealing groove 68E. The dividing component 111E is annular as a whole, and is an O-ring having a circular cross-section on a plane including the central axis of the annular ring. The dividing component 111E is fitted into the sealing groove 68E of the pilot housing 58E. The dividing component 111E is made of an elastic material with sealing properties, specifically, rubber. The dividing component 111E seals the gap between the sealing portion 112E located on its inner periphery and the radially inner wall of the sealing groove 68E by pressing the sealing portion 112E located on its inner periphery against the radially inner wall of the sealing groove 68E. The dividing component 111E seals the gap between the sealing portion 113E located on its outer periphery and the radially outer wall of the sealing groove 68E by pressing the sealing portion 113E located on its outer periphery against the radially outer wall of the sealing groove 68E.

[0455] The first damping valve 52E is composed of a disk 131E and a sealing member 132 .

[0456] The disc 131E is different from the disc 131 in that a notch 521 is formed on the inner circumference. The notch 521 is formed radially inward of the first damping valve 52E relative to the seal member 132. The passage in the notch 521 communicates with the passage in the notch 121 of the disc 50.

[0457] The opening and closing disc 57E extends to the radially outer side of the first damping valve 52E relative to the cutout 521 of the first damping valve 52E. The opening and closing disc 57E blocks the passage in the cutout 521 by abutting against the disc 131E of the first damping valve 52E in a surface contact manner. The opening and closing disc 57E opens the passage in the passage in the cutout 521 by separating from the disc 131E.

[0458] The disk 511 has an outer diameter larger than the outer diameter of the valve seat portion 78E. Fig.18 As shown in the figure, a cutout 531 is formed on the outer circumference of the disk 511. The cutout 531 includes an outer cutout portion 532 extending radially inward from the outer circumferential edge of the disk 511 and an arc-shaped inner cutout portion 533 extending from the inner end position of the outer cutout portion 532 in the radial direction of the disk 511 to both sides along the circumferential direction of the disk 511. A plurality of (specifically, four) cutouts 531 are formed on the disk 511 at equal intervals along the circumferential direction thereof.

[0459] like Fig.16 As shown, the disk 512 has an outer diameter equal to the outer diameter of the disk 511. On the disk 512, as shown in FIG. Fig.19 As shown in FIG. 1 , a plurality of (specifically, three) passage holes 535 are formed on the outer circumference of the disk 512. The passage holes 535 are arc-shaped and extend along the circumference of the disk 512. In the radial direction of the disks 511 and 512, the passage holes 535 are positioned to coincide with the inner cutouts 533. That is, the passage holes 535 and the cutouts 531 are connected.

[0460] The disk 511 contacts the valve seat 78E of the pilot housing 58E. At that time, the outer cutout 532 of the disk 511 radially crosses the valve seat 78E. Also, at that time, the inner cutout 533 of the disk 511 is located radially inside the valve seat 78E.

[0461] like Fig.16 As shown, the sealing parts 112E and 113E of the partitioning member 111E are simultaneously pressed against the radial inner and radial outer wall surfaces of the sealing groove 68E. As a result, the portion surrounded by the pilot housing 58E, the first damping valve 52E, the disks 53, 54E, 55, the opening and closing disk 57E, and the partitioning member 111E becomes the back pressure chamber 171E. The back pressure chamber 171E is always connected to the passage in the passage groove 30 of the piston rod 21 via the passage in the passage groove 468E.

[0462] Furthermore, the partition member 111E forms a variable chamber 172E between the bottom surface side of the seal groove 68E and the partition member 111E. The variable chamber 172E is always in communication with the lower chamber 20 via the passage in the passage hole 84E.

[0463] The bottomed cylindrical pilot housing 58E forms a back pressure chamber 171E inside thereof by the first damping valve 52E, the disks 53, 54E, 55, the opening and closing disk 57E and the partition member 111E. The partition member 111E is provided in the pilot housing 58E and partitions the interior of the pilot housing 58E into the back pressure chamber 171E and the variable chamber 172E.

[0464] The first damping valve 52E constitutes the first valve mechanism 41E together with the valve seat portion 47 of the piston 18. The first damping valve 52E is opened by the disc 131E being separated from the valve seat portion 47 during the extension stroke. Then, the first damping valve 52E allows the oil L from the piston side passage 43 to flow to the lower chamber 20 through the valve seat portion 47. The first valve mechanism 41E on the extension side constituted by the valve seat portion 47 and the first damping valve 52E is provided in the piston side passage 43, and the first damping valve 52E is used to open and close the piston side passage 43 and suppress the flow of the oil L, thereby generating a damping force.

[0465] The passage in the cutout 121 of the disk 50, the passage in the passage groove 30 of the piston rod 21, and the passage in the passage groove 468E of the pilot housing 58E constitute a back pressure chamber introduction passage 176E branching from the piston side passage 43. The back pressure chamber introduction passage 176E passes through the piston side passage 43 (see Figure 2 ) part so that the upper chamber 19 (refer to Figure 2 ) is connected to the back pressure chamber 171E. The back pressure chamber introduction passage 176E allows the oil L to flow from the upper chamber 19 (see Figure 2 ) is introduced into the back pressure chamber 171E through a portion of the piston side passage 43.

[0466] The passage in the passage hole 84E and the passage in the seal groove 68E, both provided in the bottom 65E of the pilot housing 58E, constitute a first passage 173E extending and connecting the back pressure chamber 171E and the lower chamber 20. A partition member 111E having seal portions 112E and 113E for sealing the first passage 173E by an elastic member is movably provided in the first passage 173E. The lower chamber 20 is located on the downstream side of the first damping valve 52E in the flow direction of the oil L in the extension stroke.

[0467] The back pressure chamber 171E causes the internal pressure to act on the first damping valve 52E in the valve closing direction along the direction of the piston 18, that is, to seat the disk 131E on the valve seat portion 47. The pilot housing 58E is a bottomed cylindrical shape and is formed with the back pressure chamber 171E that generates a force in the valve closing direction for the first damping valve 52E disposed on the opening portion 67 side.

[0468] The passages in the cutout 531 and the passage hole 535 of the second damping valve 60E, the passage between the valve seat portion 78E and the inner seat portion 77E of the pilot housing 58E, the passage in the passage groove 95E of the pilot housing 58E, the passage in the passage groove 30 of the piston rod 21, and the passage in the cutout 521 of the first damping valve 52E form the second passage 180E. The opening and closing disc 57E is provided between the second passage 180E and the back pressure chamber 171E in an openable and closable manner. The second passage 180E is provided in parallel with the first passage 173E in the passage hole 84E. The second passage 180E is arranged on the inner peripheral side of the first passage 173E in the pilot housing 58E. The opening and closing disc 57E cuts off the flow of the oil L between the back pressure chamber 171E and the second passage 180E and the lower chamber 20 in a state where it abuts against the disc 131E of the first damping valve 52E in a surface contact manner. Furthermore, the opening and closing disk 57E allows the oil L to flow between the back pressure chamber 171E, the second passage 180E, and the lower chamber 20 in a state where the opening and closing disk 57E is separated from the disk 131E.

[0469] Here, the opening and closing disc 57E allows the flow of the oil L from the lower chamber 20 and the second passage 180E to the back pressure chamber 171E via the second passage 180E when the pressure on the second passage 180E and the lower chamber 20 side becomes higher than the pressure on the back pressure chamber 171E side by a predetermined value or more. The opening and closing disc 57E restricts the flow of the oil L from the back pressure chamber 171E to the lower chamber 20 via the second passage 180E when the pressure on the back pressure chamber 171E side is higher than the pressure on the second passage 180E and the lower chamber 20 side.

[0470] The opening and closing disc 57E and the disc 131E of the first damping valve 52E constitute a communication mechanism 181E. One side of the second passage 180E can communicate with the back pressure chamber 171E. The communication mechanism 181E is located on the one side of the second passage 180E, and can communicate with the other side of the second passage 180E, that is, the lower chamber 20 side, only when the lower chamber 20 is on the upstream side. The communication mechanism 181E is a one-way valve, and the opening and closing disc 57E is a valve member of the communication mechanism 181E.

[0471] The second damping valve 60E constituted by the disks 59 , 511 , and 512 can be seated on and released from the valve seat portion 78E.

[0472] The passage in the passage groove 30 of the piston rod 21, the passage in the passage groove 95E of the pilot housing 58E, and the passage between the inner seat portion 77E and the valve seat portion 78E form a rod side passage 191E branched from the piston side passage 43. The rod side passage 191E can communicate with the upper chamber 19 and the lower chamber 20. The valve seat portion 78E and the second damping valve 60E constitute a second valve mechanism 201E that is provided in the rod side passage 191E and opens and closes the rod side passage 191E.

[0473] The second damping valve 60E of the second valve mechanism 201E is seated on the valve seat portion 78E. The second damping valve 60E 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 a portion of the piston side passage 43, a portion of the back pressure chamber introduction passage 176E, and the rod side passage 191E. In other words, the second valve mechanism 201E suppresses the flow of the oil L from the upper chamber 19 to the lower chamber 20 and generates a damping force. The second valve mechanism 201E is a damping force generating mechanism that is provided on the extension side of the rod side passage 191E and generates a damping force by the flow of the oil L.

[0474] The pilot housing 58E and the partition member 111E constitute a frequency response mechanism 211E that makes the damping force variable in response to the frequency of the reciprocating motion of the piston 18. The partition member 111E of the frequency response mechanism 211E moves and deforms according to the frequency of the reciprocating motion of the piston 18, and changes the capacity of the back pressure chamber 171E that is always connected to the upper chamber 19 and the capacity of the variable chamber 172E that is always connected to the lower chamber 20. The frequency response mechanism 211E has the partition member 111E movably provided in the first passage 173E. The frequency response mechanism 211E makes the force acting on the first damping valve 52E based on the back pressure chamber 171E variable.

[0475] During the stretching stroke, the oil L is introduced from the back pressure chamber introduction passage 176E to the back pressure chamber 171E. As a result, the back pressure chamber 171E side is higher than the lower chamber 20 side. Then, the partition member 111E maintains the sealed state with the sealing groove 68E due to the pressure of the back pressure chamber 171E, and moves toward the bottom surface side of the sealing groove 68E and abuts against the bottom surface to be compressed and deformed. As a result, the volume of the back pressure chamber 171E is expanded.

[0476] In the contraction stroke, when the lower chamber 20 side is higher than the back pressure chamber 171E side, the partition member 111E receives the pressure on the lower chamber 20 side introduced from the first passage 173E, maintains the sealing state between the partition member 111E and the sealing groove 68E, and moves toward the disk 55 side and abuts against the disk 55 to be compressed and deformed. As a result, the volume of the variable chamber 172E is expanded.

[0477] The damping force generating mechanism 10E of the sixth embodiment includes a pilot housing 58E, a frequency response mechanism 211E, a second passage 180E, and a communication mechanism 181E. The pilot housing 58E is a bottomed cylindrical shape and is formed with a back pressure chamber 171E that generates a force in the valve closing direction for the first damping valve 52E disposed on the opening 67 side. The frequency response mechanism 211E is provided with a partition member 111E having sealing portions 112E and 113E that seal the first passage 173E with an elastic member in a movably manner in the first passage 173E that is provided at the bottom 65E of the pilot housing 58E and connects the back pressure chamber 171E with the lower chamber 20, so that the force in the valve closing direction for the first damping valve 52E is variable. The second passage 180E is provided in parallel with the first passage 173E, and one side can be communicated with the back pressure chamber 171E. The communication mechanism 181E is located on the one side of the second passage 180E, and can communicate with the other side of the second passage 180E only when the lower chamber 20 is located on the upstream side.

[0478] As described above, the damping force generating mechanism 10E is provided with the first passage 173E which connects and extends the back pressure chamber 171E and the lower chamber 20 at the bottom 65E of the pilot housing 58E forming the back pressure chamber 171E. In addition, the damping force generating mechanism 10E is provided with the frequency response mechanism 211E in the first passage 173E in a movably manner by providing the partition member 111E which seals the first passage 173E with the sealing parts 112E and 113E, so that the force acting on the first damping valve 52E in the valve closing direction is variable. Therefore, although the damping force generating mechanism 10E has the frequency response mechanism 211E, it is possible to suppress the size increase.

[0479] Furthermore, the damping force generating mechanism 10E is provided with a communication mechanism 181E, so when the stroke is reversed from the contraction stroke to the extension stroke, the communication mechanism 181E opens the valve, and the oil L is introduced from the lower chamber 20, which is at a higher pressure than the upper chamber 19 in the contraction stroke, to the back pressure chamber 171E via the second passage 180E. At that time, the damping force generating mechanism 10E introduces the oil L from the lower chamber 20 to the back pressure chamber 171E via the passages in the cutout 531 and the passage hole 535 of the second damping valve 60E, the passage between the valve seat portion 78E and the inner seat portion 77E of the pilot housing 58E, the passage in the passage groove 95E of the pilot housing 58E, the passage in the passage groove 30 of the piston rod 21, and the passage in the passage groove 468E of the pilot housing 58E. As a result, the pressure in the back pressure chamber 171E can be quickly increased. As a result, the closed valve state of the first damping valve 52E, which is urged in the valve closing direction by the pressure in the back pressure chamber 171E, is stabilized. This can suppress the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke.

[0480] Furthermore, the damping force generating mechanism 10E is configured such that the second passage 180E opened and closed by the communication mechanism 181E is disposed on the inner peripheral side of the bottom portion 65E relative to the first passage 173E, and thus it is possible to suppress an increase in radial size.

[0481] Furthermore, since the damping force generating mechanism 10E uses an O-ring as the partitioning member 111E having the sealing portions 112E and 113E that seal the first passage 173E through the elastic member, the compression deformation is large. Thus, the effect of suppressing the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke by providing the connecting mechanism 181E is high.

[0482] [Seventh Embodiment]

[0483] Then, mainly based on Fig. 20 The seventh embodiment will be described with the focus on the parts that are different from the first embodiment. It should be noted that the parts that are common to the first embodiment are represented by the same names and the same symbols.

[0484] like Fig. 20 As shown, the damping force generating mechanism 10F of the shock absorber 1F including the damping force generating mechanism 10F of the seventh embodiment is different in structure from the damping force generating mechanism 10. The damping force generating mechanism 10F is provided with a disk 54F which is partially different from the disk 54 instead of the disk 54. The damping force generating mechanism 10F is provided with a pilot housing 58F which is partially different from the pilot housing 58 instead of the pilot housing 58. The opening and closing disk 57 is not provided in the damping force generating mechanism 10F.

[0485] The disk 54F is different from the disk 54 in that the notch 141 is not formed.

[0486] The pilot housing 58F is a bottomed cylindrical shape. The pilot housing 58F is integrally formed by sintering without any seams. The pilot housing 58F has a bottom 65F. The bottom 65F is a circular plate with a hole, and the mounting shaft portion 28 of the piston rod 21 is fitted on its inner circumference. The pilot housing 58F has an opening 67 on the side opposite to the bottom 65F in the axial direction of the cylindrical portion 66.

[0487] The bottom portion 65F has a bottom body portion 71F and the same inner seat portion 77 and outer seat portion 78 as described above.

[0488] The bottom body portion 71F is in the shape of a disk having a hole. The cylindrical portion 66 extends from the axial side of the bottom body portion 71F opposite to the inner seat portion 77 and the outer seat portion 78 along the axial direction of the bottom body portion 71F.

[0489] The bottom body portion 71F has a seal groove 68F formed in the middle of the bottom body portion 71F in the radial direction. The seal groove 68F is annular and is formed on the inner side of the bottom body portion 71F in the radial direction of the tubular portion 66. The seal groove 68F is recessed from the tubular portion 66 side in the axial direction of the bottom body portion 71F to the direction opposite to the tubular portion 66 in the axial direction of the bottom body portion 71F.

[0490] A passage hole 83F and a passage hole 84F are formed on the bottom body portion 71F at the bottom surface of the seal groove 68F. The passage hole 83F penetrates the bottom body portion 71F at the position of the seal groove 68F. The passage hole 83F is located at the inner end position of the bottom surface of the seal groove 68F in the radial direction of the pilot housing 58F. The passage hole 84F is located at the outer end position of the bottom surface of the seal groove 68F in the radial direction of the pilot housing 58F. A plurality of passage holes 83F and passage holes 84F are provided on the pilot housing 58F. The passage holes 83F and passage holes 84F are alternately provided on the pilot housing 58F in the circumferential direction of the pilot housing 58F.

[0491] A passage groove 468F extending radially inward from the seal groove 68F is formed on the axially opposite side of the bottom body 71F from the inner seat portion 77. The passage groove 468F connects the seal groove 68F with the passage in the passage groove 30 of the piston rod 21.

[0492] The damping force generating mechanism 10F has a partitioning component 111F (movable mechanism) in the sealing groove 68F. The partitioning component 111F is annular as a whole, and is a V-shaped V-pad having a V-shaped cross-section on a plane including the central axis of the annulus. The partitioning component 111F is embedded in the sealing groove 68F of the pilot housing 58F. At that time, the opening side of the V-letter of the partitioning component 111F faces the side opposite to the bottom surface of the sealing groove 68F. The partitioning component 111F is made of an elastic material with sealing properties, specifically, rubber. The partitioning component 111F seals the gap between the sealing portion 112F located on its inner periphery and the radially inner wall surface of the sealing groove 68F. The partitioning component 111F seals the gap between the sealing portion 113F located on its outer periphery and the radially outer wall surface of the sealing groove 68F.

[0493] The disk 55 of the damping force generating mechanism 10F abuts against the bottom body portion 71F of the pilot housing 58F.

[0494] The sealing portions 112F and 113F of the partition member 111F are simultaneously pressed against the radially inner and radially outer wall surfaces of the sealing groove 68F. As a result, the portion surrounded by the pilot housing 58F, the first damping valve 52, the disks 53, 54F, 55, and the partition member 111F becomes a back pressure chamber 171F. The back pressure chamber 171F is always connected to the passage in the passage groove 30 of the piston rod 21 via the passage in the passage groove 468F.

[0495] Furthermore, the partition member 111F forms a variable chamber 172F between the bottom surface side of the seal groove 68F and the partition member 111F. The variable chamber 172F is always in communication with the lower chamber 20 via the passages in the passage holes 83F and 84F.

[0496] The bottomed cylindrical pilot housing 58F forms a back pressure chamber 171F inside thereof by the first damping valve 52, the disks 53, 54F, 55 and the partition member 111F. The partition member 111F is provided in the pilot housing 58F and partitions the pilot housing 58F into the back pressure chamber 171F and a variable chamber 172F.

[0497] The passage in the cutout 121 of the disk 50, the passage in the passage groove 30 of the piston rod 21, and the passage in the passage groove 468F of the pilot housing 58F constitute a back pressure chamber introduction passage 176F branched from the piston side passage 43. The back pressure chamber introduction passage 176F allows the upper chamber 19 to communicate with the back pressure chamber 171F via a portion of the piston side passage 43. The back pressure chamber introduction passage 176F allows the oil L to be introduced from the upper chamber 19 on the upstream side of the back pressure chamber 171F to the back pressure chamber 171F via a portion of the piston side passage 43 during the extension stroke.

[0498] The passages in the passage holes 83F and 84F provided in the bottom 65F of the pilot housing 58F and the passage in the seal groove 68F constitute a first passage 173F extending and connecting the back pressure chamber 171F and the lower chamber 20. A partition member 111F having seal portions 112F and 113F for sealing the first passage 173F by an elastic member is movably provided in the first passage 173F.

[0499] The back pressure chamber 171F causes the internal pressure to act on the first damping valve 52 in the valve closing direction along the direction of the piston 18, that is, the disk 131 is seated on the valve seat portion 47. The pilot housing 58F is a bottomed cylindrical shape and forms the back pressure chamber 171F that generates a force in the valve closing direction for the first damping valve 52 arranged on the opening portion 67 side.

[0500] The partition member 111F is provided in the first passage 173F in an openable and closable manner. The partition member 111F cuts off the flow of the oil L between the back pressure chamber 171F and the lower chamber 20 via the first passage 173F in a state where the sealing portions 112F and 113F are simultaneously in contact with the radially inner and radially outer wall surfaces of the seal groove 68F. Furthermore, the partition member 111F allows the flow of the oil L between the back pressure chamber 171F and the lower chamber 20 via the first passage 173F in a state where the sealing portions 112F and 113F are separated from the radially inner and radially outer wall surfaces of the seal groove 68F.

[0501] Here, the partition member 111F allows the oil L from the lower chamber 20 to flow into the back pressure chamber 171F via the first passage 173F when the pressure on the lower chamber 20 side is higher than the pressure on the back pressure chamber 171B side by a predetermined value or more. The partition member 111F restricts the oil L from the back pressure chamber 171F to flow into the lower chamber 20 via the first passage 173F when the pressure on the back pressure chamber 171F side is higher than the pressure on the lower chamber 20 side.

[0502] The radially inner and radially outer wall surfaces of the dividing member 111F and the sealing groove 68F constitute a connecting mechanism 181F. One side of the first passage 173F can be connected to the back pressure chamber 171F. The connecting mechanism 181F is located on the one side of the first passage 173F, and can be connected to the other side of the first passage 173F, i.e., the lower chamber 20 side, only when the lower chamber 20 is on the upstream side. In other words, the connecting mechanism 181F cannot be connected to the other side of the first passage 173F, i.e., the lower chamber 20 side, when the lower chamber 20 is on the downstream side. The connecting mechanism 181F is between the back pressure chamber 171F and the variable chamber 172F, and restricts the flow of the oil L in one direction from the back pressure chamber 171F side to the variable chamber 172F side. On the other hand, the connecting mechanism 181F allows the flow of the oil L in the other direction from the variable chamber 172F side to the back pressure chamber 171F side. The communication mechanism 181F is a one-way valve, and the partition member 111F is a valve member of the communication mechanism 181F.

[0503] The partition member 111F opens the valve when the first passage 173F allows the oil L to flow from the lower chamber 20 to the back pressure chamber 171F. The first passage 173F is provided to connect the back pressure chamber 171F and the lower chamber 20, and is provided with the partition member 111F. The first passage 173F provided with the partition member 111F also serves as a passage in which one side can communicate with the back pressure chamber 171F and a communication mechanism 181F is provided, and the communication mechanism 181F is located on the one side and can communicate with the other side only when the lower chamber 20 side is the upstream side.

[0504] The communication mechanism 181F restricts the flow of the oil L from the upper chamber 19, the piston side passage 43, the back pressure chamber introduction passage 176F, and the back pressure chamber 171F to the lower chamber 20 via the first passage 173F. The communication mechanism 181F allows the flow of the oil L from the lower chamber 20 to the back pressure chamber 171F, the back pressure chamber introduction passage 176F, the piston side passage 43, and the upper chamber 19 via the first passage 173F.

[0505] The pilot housing 58F and the partition member 111F constitute a frequency response mechanism 211F that makes the damping force variable in response to the frequency of the reciprocating motion of the piston 18. The partition member 111F of the frequency response mechanism 211F moves and deforms according to the frequency of the reciprocating motion of the piston 18, and changes the capacity of the back pressure chamber 171F that is always connected to the upper chamber 19 and the capacity of the variable chamber 172F that is always connected to the lower chamber 20. The frequency response mechanism 211F has the partition member 111F movably provided in the first passage 173F. The frequency response mechanism 211F makes the force acting on the first damping valve 52 based on the back pressure chamber 171F variable.

[0506] The damping force generating mechanism 10F operates substantially the same as the damping force generating mechanism 10 except for the following points.

[0507] During the stretching stroke, the oil L is introduced into the back pressure chamber 171F through the back pressure chamber introduction passage 176F. And, with respect to the pressure difference between the back pressure chamber 171F and the lower chamber 20 at that time, the back pressure chamber 171F side is higher than the lower chamber 20 side. Then, under the pressure of the back pressure chamber 171F, the partition member 111F maintains the sealing state with the sealing groove 68F, and moves toward the bottom surface side of the sealing groove 68F and abuts against the bottom surface to be deformed. As a result, the volume of the back pressure chamber 171F is expanded.

[0508] In the contraction stroke, the lower chamber 20 side is at a higher pressure than the back pressure chamber 171F side. Therefore, if the pressure difference between the lower chamber 20 side and the back pressure chamber 171F side is lower than a predetermined value, the oil flows from the lower chamber 20 to the variable chamber 172F through the passages in the passage holes 83F and 84F of the first passage 173F, and the partition member 111F maintains the sealed state with the seal groove 68F under the pressure, and moves to the disk 55 side and abuts against the disk 55 to be deformed. As a result, the volume of the variable chamber 172F is expanded. In addition, in the contraction stroke, when the lower chamber 20 side becomes a pressure higher than the back pressure chamber 171F side by a predetermined value or more, the partition member 111F is deformed in such a way that the outer diameter becomes smaller and the inner diameter becomes larger, and the communication mechanism 181F opens the valve, so that the oil L flows from the lower chamber 20 to the back pressure chamber 171F through the passages in the passage holes 83F and 84F of the first passage 173F and the passages in the seal groove 68F.

[0509] The damping force generating mechanism 10F of the seventh embodiment includes a pilot housing 58F, a frequency response mechanism 211F, a first passage 173F, and a communication mechanism 181F. The pilot housing 58F is a bottomed cylindrical shape and is formed with a back pressure chamber 171F that generates a force in the valve closing direction for the first damping valve 52 disposed on the opening 67 side. The frequency response mechanism 211F is provided with a partition member 111F having sealing portions 112F and 113F that seal the first passage 173F by an elastic member in a movably manner in the first passage 173F that is provided at the bottom 65F of the pilot housing 58F and connects the back pressure chamber 171F with the lower chamber 20, so that the force in the valve closing direction for the first damping valve 52 can be varied. One side of the first passage 173F can communicate with the back pressure chamber 171F. The communication mechanism 181F is located on the one side of the first passage 173F and can communicate with the other side of the first passage 173F only when the lower chamber 20 is on the upstream side.

[0510] As described above, the damping force generating mechanism 10F is provided with the first passage 173F which connects and extends the back pressure chamber 171F and the lower chamber 20 at the bottom 65F of the pilot housing 58F forming the back pressure chamber 171F. In addition, the damping force generating mechanism 10F is provided with the frequency response mechanism 211F in the first passage 173F in a movably manner, which is provided with the partition member 111F which seals the first passage 173F with the sealing parts 112F and 113F, so that the force acting on the closing direction of the first damping valve 52 can be varied. Therefore, although the damping force generating mechanism 10F has the frequency response mechanism 211F, it is possible to suppress the size increase.

[0511] Furthermore, the damping force generating mechanism 10F is provided with a connecting mechanism 181F, so when the stroke is reversed from the contraction stroke to the extension stroke, the connecting mechanism 181F opens the valve, and the oil L is introduced from the lower chamber 20, which is at a higher pressure than the upper chamber 19 in the contraction stroke, to the back pressure chamber 171F via the first passage 173F, so that the pressure of the back pressure chamber 171F can be quickly increased. As a result, the closed valve state of the first damping valve 52, which is urged in the valve closing direction by the pressure of the back pressure chamber 171F, is stabilized. Thus, the delay in the increase of the damping force generated when the stroke is reversed from the contraction stroke to the extension stroke can be suppressed.

[0512] Furthermore, the first passage 173F provided with the partition member 111F of the damping force generating mechanism 10F also serves as a passage in which one side can communicate with the back pressure chamber 171F and a communication mechanism 181F is provided, and the communication mechanism 181F is located on the one side and can communicate with the other side only when the lower chamber 20 side is the upstream side. Thus, the size of the damping force generating mechanism 10F can be further suppressed.

[0513] Furthermore, when the partition member 111F of the damping force generating mechanism 10F is a V-gasket and the first passage 173F is on the upstream side at the lower chamber 20 side, the outer peripheral side or the inner peripheral side of the partition member 111F as the V-gasket becomes a passage for the oil L to flow from the lower chamber 20 to the back pressure chamber 171F. Therefore, the structure can be simplified, and the cost increase can be suppressed.

[0514] (Note 1)

[0515] The damping force generating mechanism of Supplementary Note 1 has:

[0516] A force generating member having a bottomed cylindrical shape and forming a back pressure chamber for causing a first damping force generating member disposed on the opening side to generate a force in a valve closing direction;

[0517] a frequency response mechanism, wherein a movable mechanism is movably provided in a first passage provided at the bottom of the force generating member and connecting the back pressure chamber and the first chamber, the movable mechanism having a sealing portion for sealing the first passage by an elastic member, so that the force is variable;

[0518] A second passage, which is parallel to or in common with the first passage, and one side of which can communicate with the back pressure chamber;

[0519] The communication mechanism is located on the one side of the second passage and is capable of communicating with the other side of the second passage only when the first chamber is located on the upstream side.

[0520] (Note 2)

[0521] The damping force generating mechanism of Appendix 2 is based on the damping force generating mechanism of Appendix 1.

[0522] The second passage is arranged on the inner peripheral side of the first passage.

[0523] (Note 3)

[0524] The damping force generating mechanism of Supplement 3 is based on the damping force generating mechanism of Supplement 1.

[0525] The second passage is arranged on the outer peripheral side of the first passage.

[0526] (Note 4)

[0527] The damping force generating mechanism of Supplement 4 is based on any damping force generating mechanism in Supplement 1 to Supplement 3.

[0528] The movable mechanism is an O-ring.

[0529] (Note 5)

[0530] The damping force generating mechanism of Supplement 5 is based on the damping force generating mechanism of Supplement 1.

[0531] The first passage also serves as the second passage.

[0532] (Note 6)

[0533] The damping force generating mechanism of Supplement 6 is based on any damping force generating mechanism in Supplement 1, Supplement 2 or Supplement 5.

[0534] The force generating member is provided with a tapered portion, and the movable mechanism is restricted in movement by the tapered portion.

[0535] (Note 7)

[0536] The damping force generating mechanism of Supplement 7 is based on the damping force generating mechanism of Supplement 6.

[0537] A passage that is always in communication is formed between the tapered portion and the outer bottom side of the force generating member.

[0538] (Note 8)

[0539] The damping force generating mechanism of Supplement 8 is based on any damping force generating mechanism in Supplement 5 to Supplement 7.

[0540] The movable mechanism includes a disk having a hole and a gasket, and is provided with a valve member capable of closing the hole, and the valve member opens when the first passage functions as the second passage.

[0541] (Note 9)

[0542] The damping force generating mechanism of Supplement 9 is based on any damping force generating mechanism in Supplement 5 to Supplement 7.

[0543] The movable mechanism is a V-pad, and when the first passage functions as the second passage, the outer peripheral side or the inner peripheral side of the V-pad serves as the second passage.

[0544] Industrial Applicability

[0545] According to the above-mentioned aspects of the present invention, a damping force generating mechanism capable of suppressing enlargement can be provided. Therefore, the present invention has high industrial applicability.

[0546] Description of Reference Numerals

[0547] 1, 1A to 1F…buffer; 2…cylinder; 10, 10A to 10F…damping force generating mechanism; 20…lower chamber (first chamber); 52, 52A, 52B, 52E…first damping valve (first damping force generating member); 57B…opening and closing disc (valve member); 58, 58A to 58F…pilot housing (force generating member); 65, 65A to 65F…bottom; 67, 67A, 67B…opening; 111, 111A to 111F…dividing member ( Movable mechanism); 112, 112A~112F, 113, 113A~113F...sealing portion; 171, 171A~171F...back pressure chamber; 173, 173A~173F...first passage; 180, 180A~180F...second passage; 181, 181A~181F...connecting mechanism; 211, 211A~211F...frequency response mechanism; 412...conical portion; 421...disc; 422...gasket; 425...passage hole (hole).

Claims

1. A damping force generating mechanism, characterized in that: have: A force generating member having a bottomed cylindrical shape and forming a back pressure chamber for causing a first damping force generating member disposed on the opening side to generate a force in a valve closing direction; a frequency response mechanism, wherein a movable mechanism is movably provided in a first passage provided at the bottom of the force generating member and connecting the back pressure chamber and the first chamber, the movable mechanism having a sealing portion for sealing the first passage by an elastic member, so that the force is variable; A second passage, which is parallel to or in common with the first passage, and one side of which can communicate with the back pressure chamber; The communication mechanism is located on the one side of the second passage and is capable of communicating with the other side of the second passage only when the first chamber is located on the upstream side.

2. The damping force generating mechanism according to claim 1, The second passage is arranged on the inner peripheral side of the first passage.

3. The damping force generating mechanism according to claim 1, The second passage is arranged on the outer peripheral side of the first passage.

4. The damping force generating mechanism according to any one of claims 1 to 3, The movable mechanism is an O-ring.

5. The damping force generating mechanism according to claim 1, The first passage also serves as the second passage.

6. The damping force generating mechanism according to claim 5, The urging force generating member is provided with a tapered portion, and the movable mechanism is restricted in movement by the tapered portion.

7. The damping force generating mechanism according to claim 6, A passage that is always in communication is formed between the tapered portion and the outer bottom side of the force generating member.

8. The damping force generating mechanism according to any one of claims 5 to 7, The movable mechanism includes a disk having a hole and a gasket, and is provided with a valve member capable of closing the hole, and the valve member opens when the first passage functions as the second passage.

9. The damping force generating mechanism according to any one of claims 5 to 7, The movable mechanism is a V-pad, and when the first passage functions as the second passage, the outer peripheral side or the inner peripheral side of the V-pad serves as the second passage.

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