SHOCK ABSORBERS AND DAMPING FORCE GENERATION MECHANISM

Abstract

This shock absorber comprises a cylinder in which a working fluid is enclosed, a piston slidably inserted into the cylinder and dividing the interior of the cylinder into a first cylinder chamber and a second cylinder chamber, a first passage through which the working fluid flows from a chamber in the cylinder due to the movement of the piston, a second passage provided parallel to the first passage, a valve mechanism provided in the first passage and operating when the first cylinder chamber is under an upstream pressure to allow adjustment of the damping force by a pressure in a main backpressure chamber, a frequency-sensitive mechanism provided in the second passage and operating when the first cylinder chamber is under an upstream pressure to change a volume according to the movement of a movable member, a check valve,which is provided in the second passage and operates when the second cylinder chamber is under an upstream pressure, and a first throttle mechanism which is provided downstream or upstream of the check valve and operates when the second cylinder chamber is under an upstream pressure to control a flow of the working fluid to the main backpressure chamber.

Description

TECHNICAL FIELD

[0001] The present invention relates to a shock absorber and a damping force generating mechanism. STATE OF THE ART

[0002] Some shock absorbers have a damping force generating mechanism in which the damping force is varied depending on the frequency (see, for example, Patent Document 1). Citation listPatent document

[0003] Patent Document 1: Unexamined Japanese Patent Application, Publication No. JP 2021-55850 A SUMMARY OF THE INVENTIONTechnical Problem

[0004] In a shock absorber, a damping force generating mechanism must function smoothly.

[0005] Therefore, the present invention provides a shock absorber and a damping force generating mechanism that enable smooth operation of the damping force generating mechanism. Solution to the problem

[0006] A shock absorber according to a first aspect of the present invention includes a cylinder in which a working fluid is enclosed, a piston slidably fitted into the cylinder and dividing the interior of the cylinder into a first cylinder chamber and a second cylinder chamber, a first passage through which the working fluid flows from a chamber in the cylinder due to the movement of the piston, a second passage provided parallel to the first passage, a valve mechanism provided in the first passage and operating when the first cylinder chamber is under an upstream pressure to enable adjustment of a damping force by a pressure in a main back pressure chamber, a frequency-sensitive mechanism provided in the second passage and operating when the first cylinder chamber is under an upstream pressure,to change a volume according to the movement of a movable element, a check valve provided in the second passage and operating when the second cylinder chamber is under an upstream pressure, and a first throttle mechanism provided downstream or upstream of the check valve and operating when the second cylinder chamber is under an upstream pressure to control a flow of the working fluid to the main backpressure chamber.

[0007] A damping force generating mechanism according to a second aspect of the present invention includes a biasing force generating member having a bottomed cylindrical shape and forming a back pressure chamber that generates a biasing force in a valve closing direction to a damping force generating element disposed on an opening side, a valve provided at a lower portion of the biasing force generating member, defining a variable chamber on a side opposite to the back pressure chamber and blocking a flow of a working fluid from the back pressure chamber to the variable chamber, and a throttle member that comes into contact with an outer peripheral side of the valve to restrict the opening of the valve, the valve having a first throttle portion that restricts an inflow of the working fluid from the variable chamber to the back pressure chamber. Advantageous effects of the invention

[0008] According to the aspects described above, it is possible to operate the damping force generating mechanism smoothly. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] A cross-sectional view showing a shock absorber of a first embodiment according to the present invention. [ Fig. 2] A cross-sectional view showing a damping force generating mechanism of the shock absorber of the first embodiment according to the present invention. [ Fig. 3] A cross-sectional view showing a configuration of a main part of the shock absorber of the first embodiment according to the present invention. [ Fig. 4] A cross-sectional view showing a configuration of a main part of the shock absorber of the first embodiment according to the present invention. [ Fig. 5] A bottom view showing a pilot housing of the shock absorber of the first embodiment according to the present invention. [ Fig. 6] A hydraulic circuit diagram showing a configuration of a main part of the shock absorber of the first embodiment according to the present invention. [ Fig. 7] A cross-sectional view showing a configuration of a main part of a shock absorber of a second embodiment according to the present invention. [ Fig. 8] A cross-sectional view showing a configuration of a main part of a shock absorber of a third embodiment according to the present invention. [ Fig. 9] A bottom view showing a pilot housing of the shock absorber of the third embodiment according to the present invention. [ Fig. 10] A hydraulic circuit diagram showing a configuration of a main part of the shock absorber of the third embodiment according to the present invention. [ Fig. 11] A cross-sectional view showing another application example of the configuration of the shock absorber of the third embodiment according to the present invention. [ Fig. 12] A cross-sectional view showing a configuration of a main part of another application example of the configuration of the shock absorber of the third embodiment according to the present invention. DESCRIPTION OF THE EMBODIMENTS [First Embodiment]

[0009] A shock absorber of a first embodiment will be described below with reference to the Fig. 1 to 6. For the sake of simplicity, a top side is shown in the Fig. 1 to 4, 6 to 8 and 10 to 12 with “top” and a bottom in the Fig. 1 to 4, 6 to 8 and 10 to 12 are marked “below”.

[0010] As in Fig. 1, a shock absorber 1 is a hydraulic twin-tube shock absorber. The shock absorber 1 is used in suspension devices of vehicles. The shock absorber 1 includes a cylinder 2 in which an oil fluid L is sealed as a working fluid. The cylinder 2 has an inner cylinder 3 and an outer cylinder 4. The inner cylinder 3 has a cylindrical shape. The outer cylinder 4 has a cylindrical shape with a bottom. The outer cylinder 4 has a larger inner diameter than the outer diameter of the inner cylinder 3. The inner cylinder 3 is arranged inside the outer cylinder 4. A central axis of the inner cylinder 3 and a central axis of the outer cylinder 4 coincide. A reservoir chamber 6 is formed between the inner cylinder 3 and the outer cylinder 4.

[0011] The outer cylinder 4 includes a tubular element 11 and a base part 12. The tubular element 11 has a cylindrical shape. The base part 12 has a cylindrical shape with a base. The base part 12 is attached to a bottom side of the tubular element 11 and secured to the tubular element 11 by welding. The base part 12 closes off a lower part of the tubular element 11. A fastening eyelet 13 is secured to the base part 12 by welding on an outer side opposite the tubular element 11 in the axial direction thereof.

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

[0013] The shock absorber 1 includes a piston rod 21. One end of the piston rod 21 in an axial direction is disposed inside the inner cylinder 3 of the cylinder 2. This one end of the piston rod 21 is connected to the piston 18. The other end of the piston rod 21, on a side opposite to the one end in the axial direction, extends from the cylinder 2 to the outside of the cylinder 2. The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 and the piston rod 21 move together. In the shock absorber 1, a stroke in which the piston rod 21 moves in a direction in which a protrusion from the cylinder 2 increases is called an extension stroke in which the entire length increases. In the shock absorber 1, a stroke in which the piston rod 21 moves in a direction to decrease a protrusion from the cylinder 2 is called a compression stroke in which the entire length decreases.In shock absorber 1, the piston 18 moves toward the upper chamber 19 side during the extension stroke. In shock absorber 1, the piston 18 moves toward the lower chamber 20 side during the compression stroke.

[0014] A rod guide 22 is attached to an upper end opening side of the inner cylinder 3 and an upper end opening side of the outer cylinder 4. A sealing member 23 is attached to an upper side of the rod guide 22 in the outer cylinder 4. A disk 24 is attached to an upper side of the sealing member 23 in the outer cylinder 4. The rod guide 22 and the sealing member 23 are both annular. The disk 24 is in the shape of a drilled, circular, flat plate with a constant thickness. The disk 24 is in contact with a portion on an outer peripheral side of the sealing member 23. The piston rod 21 slides with respect to the rod guide 22 and the sealing member 23 in an axial direction. The piston rod 21 extends from the inside of the cylinder 2 to the outside of the cylinder 2 with respect to the sealing member 23.

[0015] The rod guide 22 limits the movement of the piston rod 21 in the radial direction with respect to the inner cylinder 3 and the outer cylinder 4 of the cylinder 2. The piston rod 21 is inserted into the rod guide 22, and the piston 18 is inserted into the inner cylinder 3. A central axis of the piston rod 21 and a central axis of the cylinder 2 coincide. The rod guide 22 supports the piston rod 21 so that it is movable in an axial direction of the piston rod 21. An outer peripheral portion of the sealing element 23 is in close contact with the outer cylinder 4. An inner peripheral portion of the sealing element 23 is in close contact with an outer peripheral portion of the piston rod 21. The piston rod 21 moves in an axial direction of the sealing element 23 with respect to the sealing element 23.The sealing element 23 dams the oil fluid L in the inner cylinder 3 and the high-pressure gas and the oil fluid L in the storage chamber 6, which leak out to the outside.

[0016] An outer peripheral portion of the rod guide 22 has a larger diameter at an upper part than at a lower part. The rod guide 22 is attached to an inner peripheral portion of an upper end of the inner cylinder 3 at the lower part with the smaller diameter. The rod guide 22 is attached to an upper inner peripheral portion of the outer cylinder 4 at the upper part with the larger diameter. A bottom valve 25 is attached to the bottom part 12 of the outer cylinder 4. The bottom valve 25 is arranged in the radial direction with respect to the outer cylinder 4. The bottom valve 25 separates the lower chamber 20 and the storage chamber 6. An inner peripheral portion of a lower end of the inner cylinder 3 is attached to the bottom valve 25. An upper end part of the outer cylinder 4 is deformed inward in the radial direction of the outer cylinder 4.The sealing element 23 is fixed to the cylinder 2 together with the disc 24 by being inserted between the deformed portion and the rod guide 22.

[0017] The piston rod 21 includes a main shaft portion 27 and a fixing shaft portion 28. The fixing shaft portion 28 has an outer diameter smaller than an outer diameter of the main shaft portion 27. The fixing shaft portion 28 is arranged inside the cylinder 2. The piston 18 of the piston rod 21 is fixed to the fixing shaft portion 28. The main shaft portion 27 of the piston rod 21 slides relative to the rod guide 22 and the sealing member 23. The main shaft portion 27 has a shaft step portion 29. The shaft step portion 29 is provided at an end part of the main shaft portion 27 on the fixing shaft portion 28 side. The shaft step portion 29 extends in a direction orthogonal to the central axis of the piston rod 21.

[0018] A through groove 30 is formed in the piston rod 21 at an outer peripheral portion of the fixing shaft portion 28. The through groove 30 is formed by notching the outer peripheral portion of the fixing shaft portion 28 into a planar shape parallel to a central axis of the fixing shaft portion 28. The through groove 30 extends in an axial direction of the fixing shaft portion 28. A plurality of, specifically, two, through grooves 30 are formed at regular intervals in a circumferential direction of the fixing shaft portion 28. An external screw 31 is formed on an outer peripheral portion of an end part of the fixing shaft portion 28 on a side opposite to the main shaft portion 27 with respect to the through grooves 30 in the axial direction of the fixing shaft portion 28.

[0019] For example, the shock absorber 1 is connected to a vehicle body, with a portion of the piston rod 21 protruding from the cylinder 2 located at an upper portion. At this time, the shock absorber 1 is connected to a wheel side of the vehicle, with the mounting eyelet 13 provided on the cylinder 2 side located at a lower portion. Conversely, if the shock absorber 1 is a monotube rather than a twin-cylinder shock absorber, the cylinder 2 side of the shock absorber 1 may be connected to the vehicle body. In this case, the piston rod 21 of the shock absorber 1 is connected to the wheel side.

[0020] In the vehicle, the wheel vibrates with respect to the vehicle body when the vehicle is traveling. Then, in the shock absorber 1, the relative positions of the cylinder 2 and the piston rod 21 change according to the vibration. This change is suppressed by the fluid resistance in a flow path provided in the shock absorber 1. As described below, the fluid resistance in the flow path provided in the shock absorber 1 is designed to vary depending on the speed or amplitude of the vibration described above. The ride comfort of the vehicle is improved by the vibration suppression by the shock absorber 1.

[0021] Furthermore, in the vehicle, an inertial force or a centrifugal force generated in the vehicle body during travel acts between the cylinder 2 and the piston rod 21, in addition to the vibration generated by the wheel with respect to the vehicle body. For example, a centrifugal force is generated in the vehicle body when the driving direction is changed by steering wheel operation. Then, a force based on the centrifugal force acts between the cylinder 2 and the piston rod 21. As described below, the shock absorber 1 has satisfactory properties against vibrations based on the force generated in the vehicle body when the vehicle is traveling. High driving stability of the vehicle can be achieved by the shock absorber 1.

[0022] The shock absorber 1 has a damping force generating mechanism 33. The damping force generating mechanism 33 includes the piston 18 and has the Fig. Configuration shown in Figure 2.

[0023] The piston 18 includes a piston main body 35 and a sliding member 36. The piston main body 35 is made of metal and has an annular shape. The piston main body 35 of the piston 18 is mounted on the mounting shaft portion 28 of the piston rod 21. The sliding member 36 is made of synthetic resin and has an annular shape. The sliding member 36 is integrally fixed to an outer peripheral surface of the piston main body 35. The piston 18 slides with respect to the inner cylinder 3, with the sliding member 36 in contact with the inner cylinder 3.

[0024] A through hole 37, a through groove 38, a through hole 39, and a through groove 40 are provided in the piston main body 35. The through hole 37 penetrates the piston main body 35 in an axial direction of the piston main body 35. A plurality of through holes 37 are formed in the piston main body 35 at intervals in a circumferential direction of the piston main body 35. The through hole 39 penetrates the piston main body 35 in the axial direction of the piston main body 35. A plurality of through holes 39 are formed in the piston main body 35 at intervals in the circumferential direction of the piston main body 35. In the piston main body 35, the through holes 37 and the through holes 39 are formed alternately one after another at a regular interval in the circumferential direction of the piston main body 35.

[0025] The through groove 38 is formed in the piston main body 35 in an annular manner in the circumferential direction of the piston main body 35. The through groove 38 is formed at one end of the piston main body 35 on the lower chamber side 20 in the axial direction. All through holes 37 open into the through groove 38 on this end of the piston main body 35 in the axial direction. The through groove 40 is formed in the piston main body 35 in an annular manner in the circumferential direction of the piston main body 35. The through groove 40 is formed at one end of the piston main body 35 on the side of the upper chamber 19 opposite the through groove 38 in the axial direction. All through holes 39 open into the through groove 40 on the end of the piston main body 35 opposite the through groove 38 in the axial direction.End portions of the plurality of through holes 37 on a side opposite to the through groove 38 in the axial direction of the piston main body 35 open to an outer side of the through groove 40 in a radial direction of the piston main body 35. End portions of the plurality of through holes 39 on a side opposite to the through groove 40 in the axial direction of the piston main body 35 open to an outer side of the through groove 38 in the radial direction of the piston main body 35. In the piston 18, the inner side of the plurality of through holes 37 and the inner side of the through groove 38 form a piston-side passage 43. In the piston 18, the inner side of the plurality of through holes 39 and the inner side of the through groove 40 form a piston-side passage 44.

[0026] The damping force generating mechanism 33 has a first valve mechanism 41 (valve mechanism) provided in the piston-side passage 43. The first valve mechanism 41 opens and closes the piston-side passage 43 to generate a damping force. The first valve mechanism 41 is arranged on the lower chamber 20 side in the axial direction of the piston 18. Thereby, during the extension stroke, the piston-side passage 43 allows the oil fluid L to flow from the upper chamber 19 on one side to the lower chamber 20 on the other side via the opened first valve mechanism 41 due to the movement of the piston 18 to the upper chamber 19 side, which is one direction. The first valve mechanism 41 suppresses a flow of the oil fluid L from the piston-side passage 43 to the lower chamber 20 that occurs at this time, thereby generating a damping force.

[0027] The damping force generating mechanism 33 includes a first valve mechanism 42 provided in the piston-side passage 44. The first valve mechanism 42 opens and closes the piston-side passage 44 to generate 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, during the compression stroke, the piston-side passage 44 allows the oil fluid L to flow from the lower chamber 20 toward the upper chamber 19 via the opened first valve mechanism 42 due to the movement of the piston 18 to the lower chamber 20 side. The first valve mechanism 42 suppresses a flow of the oil fluid L from the piston-side passage 44 into the upper chamber 19 that occurs at this time, thereby generating a damping force.

[0028] The piston main body 35 has the shape of a pierced disc and has an inner peripheral portion to which the fixing shaft portion 28 of the piston rod 21 is attached.

[0029] The piston main body 35 includes a main body portion 50, an inner seat portion 51, a valve seat portion 53, an inner seat portion 55, and a valve seat portion 57. The main body portion 50 is provided at a central part of the piston main body 35 in the axial direction. The inner seat portion 51 and the valve seat portion 53 are provided at an end part of the piston main body 35 on the lower chamber 20 side in the axial direction. The inner seat portion 55 and the valve seat portion 57 are provided at an end part of the piston main body 35 on the upper chamber 19 side in the axial direction.

[0030] The inner seat portion 51 has an annular shape. The inner seat portion 51 is provided on an inner peripheral side of the main body portion 50 and protrudes from the main body portion 50 toward the lower chamber 20 side in the axial direction of the piston main body 35.

[0031] The valve seat portion 53 has an annular shape. The valve seat portion 53 is located on an outer side of the inner seat portion 51 in the radial direction of the piston main body 35. The valve seat portion 53 protrudes from the main body portion 50 toward the lower chamber 20 side in the axial direction of the piston main body 35. A distal end surface on a protruding side of the valve seat portion 53 is higher in a protruding direction in the axial direction of the piston main body 35 than a distal end surface on a protruding side of the inner seat portion 51. The valve seat portion 53 is located outside the opening of the through groove 38 on the lower chamber 20 side in the radial direction of the piston main body 35. The valve seat portion 53 forms part of the first valve mechanism 41.

[0032] The inner seat portion 55 has an annular shape. The inner seat portion 55 is provided on an inner peripheral side of the main body portion 50 and protrudes from the main body portion 50 toward the upper chamber 19 side in the axial direction of the piston main body 35.

[0033] The valve seat portion 57 has an annular shape. The valve seat portion 57 is located on an outer side of the inner seat portion 55 in the radial direction of the piston main body 35. The valve seat portion 57 protrudes from the main body portion 50 toward the upper chamber 19 side in the axial direction of the piston main body 35. A distal end surface on a protruding side of the valve seat portion 57 is higher in the protruding direction in the axial direction of the piston main body 35 than a distal end surface on a protruding side of the inner seat portion 55. The valve seat portion 57 is located outside the opening of the through groove 40 on the upper chamber 19 side in the radial direction of the piston main body 35. The valve seat portion 57 forms part of the first valve mechanism 42.

[0034] As in Fig. 3, the damping force generating mechanism 33 includes a disc 70, a disc 71, a first damping valve 72 (damping force generating element), a disc 73, a plurality of, in particular four, discs 74, a plurality of, in particular three, discs 75, a disc 76, a disc 77, a throttle disc 78 (limiting element), a disc 79, a disc 79, a pilot housing 81 (damping force generating element), a second damping valve 84 formed of a plurality of, in particular three, discs 83, a disc 85, a disc 86 and an annular member 87 on the inner seat portion 51 side in the axial direction of the piston 18 in this order from the inner seat portion 51 side in the axial direction of the piston 18.

[0035] The damping force generating mechanism 33 also includes a disk 91 and a disk 92 between the throttle disk 78 and the pilot housing 81. The disks 91 and 92 are arranged to surround the disk 79 from an outer side in the radial direction of the disk 79. Of the disks 91 and 92, the disk 91 is provided on the side of the throttle disk 78, and the disk 92 is provided on a side opposite the throttle disk 78.

[0036] The discs 70, 71, 73 to 77, 79, 83, 85, 86, 91, and 92, the throttle disc 78, the pilot housing 81, and the annular member 87 are all made of a single metal. The discs 70, 71, 73 to 77, 79, 83, 85, 86, 91, and 92 and the annular member 87 each have a drilled circular flat plate shape with a constant thickness. The discs 70, 71, 73 to 77, 79, 83, 85, 86, 91, and 92 are manufactured by press forming. The first damping valve 72, the throttle disc 78, and the pilot housing 81 are all annular. The fixing shaft portion 28 of the piston rod 21 is attached to an inner side of all of the discs 70, 71, 73 to 77, 79, 83, 85 and 86, the first damping valve 72, the throttle disc 78, the pilot housing 81 and the annular member 87.

[0037] The piston 18, the discs 70, 71, 73 to 77, 79 and 83, the first damping valve 72, the throttle disc 78 and the pilot housing 81 cover the through groove 30 of the piston rod 21 and form a pilot chamber 95 within the through groove 30.

[0038] The pilot housing 81 has a cylindrical shape with a bottom. The pilot housing 81 is seamlessly and integrally formed as a whole by sintering. The pilot housing 81 has a bottom portion 101 and a cylindrical portion 102.

[0039] The bottom portion 101 is in the shape of a drilled disc and has an inner peripheral portion to which the mounting shaft portion 28 of the piston rod 21 is attached. The cylindrical portion 102 has a cylindrical shape and extends from an outer peripheral portion of the bottom portion 101 to one side of the bottom portion 101 in the axial direction. The pilot housing 81 has an opening 103 on a side of the cylindrical portion 102 opposite the bottom portion 101 in the axial direction. In other words, the pilot housing 81 has a bottomed cylindrical shape, having the opening 103 at one end in the axial direction.

[0040] The bottom portion 101 has a lower main body portion 111, an inner seat portion 112, a valve seat portion 113, an outer seat portion 114, an inner seat portion 115, and an outer seat portion 116.

[0041] The lower main body portion 111 has the shape of a drilled disc, and the fixing shaft portion 28 of the piston rod 21 is attached to an inner peripheral side thereof. As shown in Fig. 4, a through hole 121 penetrating the lower main body portion 111 in an axial direction of the lower main body portion 111 is formed in the lower main body portion 111. As shown in Fig. 5, a plurality of, in particular four, through holes 121 are provided in the lower main body portion 111 at regular intervals in a circumferential direction of the lower main body portion 111.

[0042] As in Fig. 3 and Fig. As shown in Figure 4, the inner seat portion 112 is formed on an inner peripheral side of the lower main body portion 111. The inner seat portion 112 has an annular shape. The inner seat portion 112 protrudes from the lower main body portion 111 to the same side as the cylindrical portion 102 in the axial direction of the lower main body portion 111. A through groove 124 is formed in the inner seat portion 112, penetrating the inner seat portion 112 in the radial direction of the inner seat portion 112.

[0043] The valve seat portion 113 is formed to be continuous with the inner seat portion 112 on an outer side of the inner seat portion 112 in the radial direction of the lower main body portion 111. The valve seat portion 113 has an annular shape. The valve seat portion 113 protrudes from the lower main body portion 111 to the same side as the inner seat portion 112 in the axial direction of the lower main body portion 111. In an axial direction of the pilot housing 81, a height of a distal end surface on a protruding side of the valve seat portion 113 is lower than a height of a distal end surface on a protruding side of the inner seat portion 112 and is equal to a height of a groove bottom surface of the through groove 124.

[0044] The outer seat portion 114 is formed to be continuous with the cylindrical portion 102 on an inner side of the cylindrical portion 102 in the radial direction of the lower main body portion 111. The outer seat portion 114 is formed to be spaced apart from the valve seat portion 113 on an outer side of the valve seat portion 113 in the radial direction of the lower main body portion 111. The outer seat portion 114 has an annular shape. The outer seat portion 114 protrudes from the lower main body portion 111 on the same side as the inner seat portion 112 and the valve seat portion 113 in the axial direction of the lower main body portion 111. In the axial direction of the pilot housing 81, a height of a distal end surface on a protruding side of the outer seat portion 114 is slightly lower than a height of the distal end surface on a protruding side of the valve seat portion 113.

[0045] In the bottom portion 101, an annular recessed portion 125, which is recessed from the cylindrical portion 102 side to a side opposite the cylindrical portion 102 in the axial direction, is formed by the lower main body portion 111, the valve seat portion 113, and the outer seat portion 114. The annular recessed portion 125 has an annular shape extending in a circumferential direction of the bottom portion 101. The annular recessed portion 125 is recessed from the distal end surface on the projecting side of the valve seat portion 113 and the distal end surface on the projecting side of the outer seat portion 114 to a side opposite the cylindrical portion 102 in the axial direction of the pilot housing 81. A bottom surface of the annular recessed portion 125 is formed by the lower main body portion 111.The through hole 121 is formed between the valve seat portion 113 and the outer seat portion 114 in the radial direction of the lower main body portion 111 and opens to the bottom surface of the annular recessed portion 125.

[0046] The inner seat portion 115 is formed on an inner peripheral side of the lower main body portion 111. The inner seat portion 115 has a ring shape. The inner seat portion 115 protrudes from a portion of the lower main body portion 111 on an inner peripheral side to a side opposite the inner seat portion 112 in the axial direction of the lower main body portion 111. As shown in Fig. 3, a through groove 132 is formed in the inner seat portion 115, which penetrates the inner seat portion 115 in a radial direction of the inner seat portion 115. As shown in Fig. 5, a plurality of, in particular four, through grooves 132 are provided in the inner seat portion 115 at regular intervals in a circumferential direction of the inner seat portion 115.

[0047] The outer seat portion 116 is formed on an outer side of the inner seat portion 115 in the radial direction of the lower main body portion 111. As shown in Fig. 3, the outer seat portion 116 projects radially outwardly of the inner seat portion 115 from the lower main body portion 111 to the same side as the inner seat portion 115 in the axial direction of the lower main body portion 111. As shown in Fig. 5, the outer seat portion 116 is a petal-like, non-circular seat. The outer seat portion 116 has a plurality of, specifically four, seat components 133. These seat components 133 have the same shape and are arranged at regular intervals in a circumferential direction of the pilot housing 81. The plurality of seat components 133 extend radially from the inner seat portion 115. As shown in Fig. 3, in the axial direction of the pilot housing 81, the positions of the distal end surfaces of the plurality of seat components 133 on a side opposite to the lower main body part 111 are at the same position as a position of a distal end surface of the inner seat portion 115 on a side opposite to the lower main body part 111.

[0048] A recessed passage portion 134 is formed on an inner side of each seat component 133. As shown in Fig. 5, the recessed passage portion 134 is formed by being surrounded by a part of the inner seat portion 115 and the seat component 133. As shown in Fig. 3, the recessed passage portion 134 is recessed in the axial direction of the pilot housing 81 from a distal end surface on a protruding side of the inner seat portion 115 and a distal end surface on a protruding side of the seat component 133. A bottom surface of the recessed passage portion 134 is formed by the lower main body portion 111. As shown in Fig. As shown in Figure 5, the recessed through portion 134 is formed within each of the seat components 133. In the circumferential direction of the pilot housing 81, the recessed through portions 134 and the through grooves 132 of the inner seat portion 115 are in phase with each other. The through grooves 132 are provided in the inner seat portion 115 to open toward the inside of the recessed through portions 134, respectively.

[0049] The through-hole 121 is located between adjacent seat components 133 in the circumferential direction of the pilot housing 81. Therefore, the through-hole 121 is located outside the outer seat part 116. The pilot housing 81 has four sections located between adjacent seat components 133 in the circumferential direction, and the through-hole 121 is provided at each of the four sections.

[0050] The Fig. 3 and Fig. The disc 70 shown in Figure 4 has a constant outer diameter over its entire circumference. The disc 70 has an outer diameter that is larger than the outer diameter of the inner seat portion 51 of the piston 18. A notch 141 is formed in the disc 70. The notch 141 extends radially outward from an inner peripheral edge portion of the disc 70, which is fitted onto the mounting shaft portion 28. The notch 141 penetrates the disc 70 in an axial direction of the disc 70. The notch 141 of the disc 70, together with the piston 18 and the disc 71, forms an inlet port 142.

[0051] The disc 71 has a constant outer diameter over the entire circumference and also a constant inner diameter over the entire circumference. The disc 71 has an outer diameter that is smaller than the outer diameter of the disc 70. The disc 71 is provided on an inner side of an outer end position of the notch 141 in a radial direction of the disc 70 and, together with the notch 141, forms the inlet opening 142.

[0052] The first damping valve 72 is formed from a disc 151 and a sealing element 152.

[0053] The disc 151 is made of metal and has a drilled circular flat plate shape with a constant thickness. The disc 151 is formed by press forming. The disc 151 has a constant outer diameter over the entire circumference and also a constant inner diameter over the entire circumference. The outer diameter of the disc 151 is larger than the outer diameter of the valve seat portion 53 of the piston 18. The fixing shaft portion 28 of the piston rod 21 is attached to an inner peripheral side of the disc 151. In the first damping valve 72, the disc 151 comes into contact with the valve seat portion 53.

[0054] A passage in the inlet opening 142 of the disc 70 is in constant communication with the piston-side passage 43 and the pilot chamber 95.

[0055] When the disc 151 separates from the valve seat part 53 and comes into contact with it, the first damping valve 72 opens and closes an opening of the piston-side passage 43 on the side of the lower chamber 20, which is formed in the piston 18 and in Fig. 3 is shown.

[0056] The sealing element 152 is made of an elastic material with sealing properties, particularly rubber. The sealing element 152 has a ring shape. The sealing element 152 is fixed to an outer peripheral side of the disc 151. The sealing element 152 is attached to an inner peripheral surface of the cylindrical portion 102 of the pilot housing 81 on the side of the opening 103 over the entire circumference. The sealing element 152 is axially displaceable with respect to the inner peripheral surface of the cylindrical portion 102. The sealing element 152 constantly seals a gap between the first damping valve 72 and the cylindrical portion 102. The pilot housing 81 has the opening 103 in which the first damping valve 72 is arranged.

[0057] Disc 73 has a constant outer diameter over its entire circumference and also a constant inner diameter over its entire circumference. Disc 73 has an outer diameter that is smaller than the minimum inner diameter of sealing element 152. Disc 73 has an outer diameter that corresponds to the outer diameter of disc 70.

[0058] Disc 74 has a constant outer diameter across its entire circumference and also a constant inner diameter across its entire circumference. Disc 74 has an outer diameter that is smaller than the outer diameter of disc 73. Disc 74 has an outer diameter that is equal to the outer diameter of disc 71.

[0059] Disc 75 has a constant outer diameter across its entire circumference and also a constant inner diameter across its entire circumference. Disc 75 has an outer diameter that is larger than the outer diameter of disc 73 and larger than the outer diameter of disc 74.

[0060] Disc 76 has a constant outer diameter across its entire circumference and also a constant inner diameter across its entire circumference. Disc 76 has an outer diameter that is larger than the outer diameter of disc 75.

[0061] The disc 77 has a constant inner diameter over the entire circumference. The disc 77 has an outer diameter corresponding to the outer diameter of the disc 76. A notch 155 is formed in the disc 77. The notch 155 extends radially inward from an outer peripheral edge portion of the disc 77. The notch 155 penetrates the disc 77 in the axial direction of the disc 77. The notch 155 has an inner portion in the radial direction of the disc 77 with an arc shape that extends long in the circumferential direction of the disc 77, and the inner portion in the radial direction of the disc 77 is longer in the circumferential direction of the disc 77 than an outer portion of the notch 155 in the radial direction of the disc 77. A plurality of notches 155 are provided in the disc 77 at regular intervals in the circumferential direction of the disc 77.

[0062] The throttle plate 78 includes a plate 161 on the side of the plate 77 and a plate 162 on a side opposite the plate 77 in the axial direction of the throttle plate 78. The plates 161 and 162 are both made of a metal and have a drilled, circular, flat plate shape with a constant thickness. Both the plate 161 and the plate 162 are formed by press forming.

[0063] The disc 161 has a constant outer diameter over its entire circumference and also has a constant inner diameter over its entire circumference. The disc 161 has an outer diameter that is larger than the outer diameters of the discs 76 and 77 and smaller than an inner diameter of the cylindrical portion 102 of the pilot housing 81. The fixing shaft portion 28 of the piston rod 21 is attached to an inner peripheral side of the disc 161. A through hole 165 is formed in the disc 161, penetrating the disc 161 in its axial direction. The through hole 165 has an arc shape that extends long in a circumferential direction of the disc 161. The through hole 165 is aligned in the radial direction of the disks 77 and 161 with an inner portion of the notch 155 of the disk 77 in the radial direction of the disk 77, which has an arc shape extending along the circumferential direction of the disk 77.A plurality of through holes 165 are provided in the disc 161 at regular intervals in the circumferential direction of the disc 161. A passage in the through hole 165 communicates with a passage in the notch 155 of the disc 77. The notch 155 of the disc 77 and the through hole 165 of the disc 161 form a communication opening 166 (second throttle mechanism).

[0064] The disc 162 has a constant outer diameter over the entire circumference and also has a constant inner diameter over the entire circumference. The disc 162 has an outer diameter that is slightly larger than the outer diameter of the disc 161 and smaller than the inner diameter of the cylindrical portion 102 of the pilot housing 81. The disc 162 has an inner diameter that is larger than the inner diameter of the disc 161 and larger than the outer diameter of the valve seat portion 113 of the pilot housing 81. The disc 162 is arranged coaxially with the disc 161 and is located on an outer side of the through hole 165 in the radial direction of the disc 161. The disc 162 is integrated with the disc 161 by being ring-welded to the disc 161.

[0065] The disc 79 has a constant outer diameter over its entire circumference and also has a constant inner diameter over its entire circumference. The disc 79 has an outer diameter that is smaller than the inner diameter of the disc 162 of the throttle disc 78. The disc 79 is arranged within the through hole 165 in the radial direction of the throttle disc 78. The disc 79 has an outer diameter that is equal to the outer diameter of the inner seat portion 112 of the pilot housing 81.

[0066] The disc 83 has a constant outer diameter over its entire circumference and also has a constant inner diameter over its entire circumference. The disc 83 has an outer diameter equal to the outer diameter of the outer seat portion 116 of the pilot housing 81.

[0067] Disc 85 has a constant outer diameter across its entire circumference and also a constant inner diameter across its entire circumference. Disc 85 has an outer diameter that is smaller than the outer diameter of disc 83.

[0068] Disc 86 has a constant outer diameter over its entire circumference and also has a constant inner diameter over its entire circumference. Disc 86 has an outer diameter that is smaller than the outer diameter of disc 85. Disc 86 has an outer diameter that is equal to the outer diameter of the inner seat portion 115 of pilot housing 81.

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

[0070] The disc 91 has a constant outer diameter over its entire circumference. The disc 91 has an outer diameter slightly larger than the outer diameter of the disc 162 of the throttle disc 78 and slightly smaller than the inner diameter of the cylindrical portion 102 of the pilot housing 81. The disc 91 has an inner diameter smaller than the outer diameter of the valve seat portion 113 of the pilot housing 81 and larger than the outer diameter of the inner seat portion 112 of the valve seat portion 113 and the disc 79. The disc 91 has a notch 171 formed on an inner peripheral side. The notch 171 extends radially outward from an inner peripheral edge portion of the disc 91. The notch 171 penetrates the disc 91 in an axial direction of the disc 91.

[0071] Disc 92 has a constant outer diameter over its entire circumference and also a constant inner diameter over its entire circumference. Disc 92 has an outer diameter equal to the outer diameter of disc 91 and an inner diameter equal to the inner diameter of disc 91. Disc 92 has an outer diameter larger than the inner diameter of the outer seat portion 114 of pilot housing 81.

[0072] The throttle disc 78 presses an outer peripheral side of the discs 91 and 92 against the outer seat portion 114 of the pilot housing 81. At this time, the disc 162 of the throttle disc 78 comes into contact with the outer peripheral side of the disc 91, and the outer peripheral side of the disc 92 comes into contact with the outer seat portion 114. The throttle disc 78, together with the discs 75 to 77, prevents the outer peripheral side of the discs 91 and 92 from being separated, ie, opened, from the outer seat portion 114 of the pilot housing 81.

[0073] As described above, in the axial direction of the pilot housing 81, the height of the outer seat portion 114 in a protruding direction is smaller than that of the valve seat portion 113. Therefore, the discs 91 and 92, in a state where they are pressed against the outer seat portion 114 by the throttle disc 78, are elastically deformed in the axial direction so that an inner peripheral side thereof is positioned closer to the disc 161 side of the throttle disc 78 than an outer peripheral side, resulting in the inner peripheral side being pressed against the valve seat portion 113. At this time, the disc 92 comes into contact with the valve seat portion 113 over the entire circumference.

[0074] An area surrounded by the first damping valve 72, the discs 73 to 77, the throttle disc 78, and the pilot housing 81 forms the main backpressure chamber 181. An area surrounded by the throttle disc 78 and the discs 91 and 92 forms a secondary backpressure chamber 182. The through-bore 165 opens into the secondary backpressure chamber 182. An area surrounded by the annular recess 125 of the pilot housing 81 and the disc 92 forms a variable chamber 183.

[0075] The communication port 166, formed by the notch 155 of the disc 77 and the through hole 165 of the disc 161, is provided between the main backpressure chamber 181 and the sub-backpressure chamber 182. In other words, the sub-backpressure chamber 182 is connected to the main backpressure chamber 181 through a passage in the communication port 166.

[0076] As in Fig. 4, the variable chamber 183 communicates with the lower chamber 20 via a passage in the through hole 121 of the pilot housing 81. The volume of the variable chamber 183 can be changed by deforming the discs 91 and 92. That is, when the discs 91 and 92 deform to approach a bottom surface of the annular recessed portion 125, the volume of the variable chamber 183 decreases, thereby increasing the volume of the rear pressure chamber 182. When the discs 91 and 92 are deformed from this state to be separated from the bottom surface of the annular recessed portion 125, the volume of the variable chamber 183 increases, thereby decreasing the volume of the sub-back pressure chamber 182.

[0077] The main backpressure chamber 181, the connecting port 166, and the secondary backpressure chamber 182 form a backpressure chamber 184. The bottomed cylindrical pilot housing 81, together with the first damping valve 72 arranged on the side of the port 103, forms the backpressure chamber 184.

[0078] In a state where a pressure in the sub-backpressure chamber 182 is equal to or higher than a pressure in the variable chamber 183, the disc 92 of the discs 91 and 92 comes into contact with the valve seat portion 113 over its entire circumference. As a result, the discs 91 and 92 and the valve seat portion 113 throttle the flow of the oil fluid L from the pilot chamber 95 and the sub-backpressure chamber 182 into the variable chamber 183. In a state where the pressure in the variable chamber 183 is higher than the pressure in the sub-backpressure chamber 182, the discs 91 and 92 are separated from the valve seat portion 113. As a result, the discs 91 and 92 and the valve seat portion 113 allow the oil fluid L to flow from the variable chamber 183 to the pilot chamber 95 and the sub-backpressure chamber 182.Therefore, the discs 91 and 92 and the valve seat portion 113 form a check valve 191 that restricts the flow of the oil fluid L from the pilot chamber 95 and the sub-back pressure chamber 182 to the variable chamber 183, while allowing the flow of the oil fluid L from the variable chamber 183 to the pilot chamber 95 and the sub-back pressure chamber 182.

[0079] The discs 91 and 92 deform and move in a substantially integrated manner while remaining overlapped. The discs 91 and 92 form a movable valve 192 (movable element) of the check valve 191. The valve 192 is provided in the bottom portion 101 of the pilot housing 81, confines the variable chamber 183 on a side opposite the backpressure chamber 184, and blocks the flow of oil fluid L from the backpressure chamber 184 to the variable chamber 183.

[0080] When the check valve 191 opens, a portion of the deformation valve 192 on the inner peripheral side of the disc 161 approaches the throttle disc 78, narrowing a flow path between the portion and the disc 161. The inner peripheral side portion of the valve 192 and the disc 161 of the throttle disc 78 form a variable orifice 193 (first throttle mechanism, first throttle portion). The variable orifice 193 has a flow path cross-sectional area smaller than the flow path cross-sectional area of ​​the connecting port 166. The variable orifice 193 is provided between the pilot chamber 95 and the sub-back pressure chamber 182 and changes a cross-sectional area of ​​a flow path between the pilot chamber 95 and the sub-back pressure chamber 182 according to the amount of deformation of the valve 192.That is, the variable orifice 193 reduces the flow path between the pilot chamber 95 and the sub-backpressure chamber 182 as the amount of deformation of the valve 192 increases. The variable orifice 193 has a passage in the notch 171 of the disc 91. The passage in the notch 171 of the disc 91 sets the cross-sectional area of ​​the flow path within the variable orifice 193 to a minimum non-zero value when the disc 91 of the valve 192 comes into contact with the disc 161 of the throttle disc 78. In this way, the valve 192 forms the variable orifice 193, which limits the inflow of oil fluid L from the variable chamber 183 into the sub-backpressure chamber 182. The valve 192 also serves as a check valve 191. The secondary backpressure chamber 182 is provided between the variable orifice 193 and the main backpressure chamber 181.

[0081] The disc 151 of the first damping valve 72 sits on the valve seat part 53 of the piston 18. When the first damping valve 72 is separated from the valve seat part 53 of the piston 18, the oil fluid L can flow from the upper chamber 19 to the lower chamber 20 through the piston-side passage 43, which is in Fig. 3 and a passage between the disc 151 and the valve seat part 53. The piston-side passage 43 and the passage between the disc 151 and the valve seat part 53 form a first passage 201, which provides a connection between the upper chamber 19 and the Fig. 2. The first damping valve 72 is provided in the first passage 201 and suppresses a flow of the oil fluid L caused by the sliding of the piston 18 toward the extension side, thereby generating a damping force. The first damping valve 72, together with the valve seat part 53 of the piston 18, forms the first valve mechanism 41. The first valve mechanism 41 opens when the upper chamber 19 is under an upstream pressure, thereby throttling the flow of the oil fluid L. The first passage 201 serves as an extension-side passage through which the oil fluid L flows as the working fluid from the upper chamber 19 on one side to the lower chamber 20 on the other side during the movement of the piston 18 toward the upper chamber 19 side, that is, during the extension stroke.The first valve mechanism 41 on the extension side, formed of the valve seat portion 53 and the first damping valve 72, is provided in the first passage 201 and opens and closes the first passage 201 with the first damping valve 72 to suppress a flow of the oil fluid L and thereby generate a damping force. The first valve mechanism 41 is capable of adjusting the damping force by a pressure in the main back pressure chamber 181 of the back pressure chamber 184. The lower chamber 20 is located on a downstream side of the first damping valve 72 in a direction in which the oil fluid L flows in the first passage 201 during the extension stroke.

[0082] As in Fig. 3, the second damping valve 84, which is formed from a plurality of discs 83, has an outer diameter slightly larger than the maximum outer diameter of a distal end surface of the outer seat portion 116. The second damping valve 84 can be separated from and fitted onto the outer seat portion 116.

[0083] The piston-side passage 43, the passage in the inlet opening 142 of the disc 70, the pilot chamber 95 on the side of the piston rod 21, the passage in the variable opening 193, the back pressure chamber 184 and the passage between the second damping valve 84 and the outer seat portion 116 during the opening of the valve form a second passage 202 which provides communication between the upper chamber 19 and the Fig. 2 shown lower chamber 20.

[0084] A part of the second passage 202, except for the piston-side passage 43, which is shared with the first passage 201, is provided parallel to the first passage 201, thereby enabling communication between the upper chamber 19 and the lower chamber 20. The inlet port 142, the pilot chamber 95, the variable port 193, the sub-backpressure chamber 182, the connecting port 166 and the main backpressure chamber 181, which are in Fig. 3 are provided in the second pass 202.

[0085] The outer seat portion 116 and the second damping valve 84 are provided in the second passage 202 and form a second valve mechanism 205 that opens and closes the second passage 202. The second damping valve 84 of the second valve mechanism 205 sits on the outer seat portion 116. The second damping valve 84 opens to resist the flow of oil fluid L from the upper chamber 19 to the lower chamber 20 through the second passage 202 during the extension stroke. In other words, the second valve mechanism 205 suppresses the flow of oil fluid L from the upper chamber 19 to the lower chamber 20, thereby generating a damping force. The second valve mechanism 205 is an extension-side damping force generating mechanism provided in the second passage 202 and generates a damping force due to the flow of oil fluid L.

[0086] The back pressure chamber 184 causes an internal pressure to act on the first damping valve 72 toward the piston 18, that is, in a valve-closing direction in which the disc 151 sits on the valve seat portion 53. The pilot housing 81 has a bottomed cylindrical shape and forms the back pressure chamber 184, which generates a biasing force in a valve-closing direction on the first damping valve 72 located on the orifice 103 side. In other words, the back pressure chamber 184 generates a biasing force in the valve-closing direction on the first damping valve 72, causing it to come into contact with the valve seat portion 53 of the piston 18.

[0087] As in Fig. As shown in Figure 4, the inside of the through-hole 121 provided in the bottom portion 101 of the pilot housing 81 forms a lower chamber communication passage 211, which enables communication between the variable chamber 183 and the lower chamber 20. When a volume of the variable chamber 183 is reduced by the valve 192, the lower chamber communication passage 211 discharges the oil fluid L of the variable chamber 183 to the lower chamber 20. The variable chamber 183 and the lower chamber communication passage 211 also form the second passage 202.

[0088] The valve 192 of the check valve 191 is provided so that it can be opened and closed between the lower chamber communication passage 211 and the variable chamber 183 as well as the back pressure chamber 184 and the pilot chamber 95. In a state where the valve 192 of the check valve 191 is in contact with the valve seat portion 113 of the pilot housing 81, the valve 192 blocks a flow of the oil fluid L between the back pressure chamber 184 and the pilot chamber 95, as well as the variable chamber 183, the lower chamber communication passage 211, and the lower chamber 20. Even in a state where the valve 192 of the check valve 191 is separated from the valve seat portion 113, the valve 192 allows a flow of the oil fluid L between the lower chamber 20, the lower chamber communication passage 211, and the variable chamber 183, as well as the back pressure chamber 184 and the pilot chamber 95.

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

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

[0091] The first compression-side valve mechanism 42 includes a disc 221, a disc 222, a plurality of, specifically, three discs 223, a disc 224, a disc 225, and an annular member 226 on the inner seat portion 55 side in the axial direction of the piston 18 in this order from the inner seat portion 55 side in the axial direction of the piston 18. The discs 221 to 225 and the annular member 226 are made of a metal and have a drilled circular flat plate shape with a constant thickness. The discs 221 to 225 are formed by press forming. The fixing shaft portion 28 of the piston rod 21 is attached to the inner side of all the discs 221 to 225 and the annular member 226.

[0092] The disc 221 has an outer diameter corresponding to the outer diameter of the inner seat part 55 of the piston 18.

[0093] The disc 222 has an outer diameter that is slightly larger than the outer diameter of the disc 221.

[0094] The plurality of discs 223 form a first damping valve 231. The first damping valve 231 has an outer diameter that is slightly larger than the outer diameter of the valve seat portion 57 of the piston 18.

[0095] The disc 224 has an outer diameter that is smaller than the outer diameter of the plurality of discs 223 and equal to the outer diameter of the disc 221.

[0096] The disc 225 has an outer diameter that is larger than the outer diameter of the disc 224.

[0097] The annular member 226 has an outer diameter that is larger than the outer diameter of the disc 225 and smaller than the outer diameter of the disc 223. The annular member 226 has a greater thickness and higher rigidity than disc 223. The annular member 226 is in contact with the shaft step portion 29 of the piston rod 21.

[0098] The disc 225 and the annular member 226 suppress the deformation of the first damping valve 231 in an opening direction beyond a certain limit.

[0099] The first damping valve 231, formed of a plurality of discs 223, forms the first valve mechanism 42 together with the valve seat portion 57 of the piston 18. The first damping valve 231 opens by being separated from the valve seat portion 57. Then, the first damping valve 231 allows the oil fluid L to flow from the piston-side passage 44 into the upper chamber 19 through a gap between itself and the valve seat portion 57. The piston-side passage 44 and the passage between the first damping valve 231 and the valve seat portion 57 form a compression-side first passage 232 through which the oil fluid L in the lower chamber 20 flows to the lower chamber 20 side due to the movement of the piston 18. During the compression stroke, the first passage 232 allows the oil fluid L as working fluid to flow from the lower chamber 20 on one side to the upper chamber 19 on the other side.The compression-side first valve mechanism 42, formed of the valve seat portion 57 and the first damping valve 231, is provided in the first passage 232. The first valve mechanism 42 opens and closes the first passage 232 with the first damping valve 231 to suppress the flow of the oil fluid L, thereby generating a damping force.

[0100] Continue as in Fig. 6, a fixed opening 235 is provided in the shock absorber 1. The fixed opening 235 enables a constant connection between the upper chamber 19 and the lower chamber 20 via the Fig. 2. The fixed opening 235 is formed, for example, by notching the valve seat portion 57 and / or the first damping valve 231 of the compression-side first valve mechanism 42. Furthermore, the fixed opening 235 may also be formed by notching the valve seat portion 53 of the extension-side first valve mechanism 41, or it is also possible to combine the fixed openings for both the extension side and the compression side.

[0101] The Fig. The pilot housing 81 shown in Figure 4 and the valve 192 constitute a frequency-sensitive mechanism 241 that makes a damping force variable depending on the frequency of the reciprocating movement of the piston 18 (hereinafter referred to as the piston frequency). The frequency-sensitive mechanism 241 consists of a part of the sub-back pressure chamber 182 that enlarges as the disc 92 deforms to approach the bottom surface of the annular recessed portion 125, the variable chamber 183, and the valve 192 separating them. The frequency-sensitive mechanism 241 is an accumulator. The frequency-sensitive mechanism 241 is provided in the second passage 202, which includes the lower chamber communication passage 211.In the frequency-sensitive mechanism 241, the valve 192 moves and deforms depending on the frequency of the reciprocating motion of the piston 18, thereby changing the volume of the backpressure chamber 184, which is in constant communication with the upper chamber 19, and the volume of the variable chamber 183, which is in constant communication with the lower chamber 20. The frequency-sensitive mechanism 241 includes the valve 192 movably provided in the second passage 202, which includes the lower chamber communication passage 211. The frequency-sensitive mechanism 241 varies the biasing force exerted on the first damping valve 72 by the backpressure chamber 184.

[0102] During the extension stroke, the sub-back pressure chamber 182 side of the back pressure chamber 184 has a higher pressure than one side of the variable chamber 183, the lower chamber communication passage 211, and the lower chamber 20. Then, the valve 192, which receives the pressure of the sub-back pressure chamber 182, deforms toward the bottom surface side of the annular recessed portion 125. As a result, the volume of the back pressure chamber 184 increases, and the volume of the variable chamber 183 decreases. In this way, the frequency-sensitive mechanism 241 operates when the upper chamber 19 is under an upstream pressure and acts to vary the damping force in response to the piston frequency.In other words, the frequency-sensitive mechanism 241 changes the volume of the variable chamber 183 due to the movement of the valve 192 caused by the deformation during the extension stroke, thereby changing the volume of the backpressure chamber 184 as a result.

[0103] During the compression stroke, one side of the lower chamber 20, the lower chamber communication passage 211, and the variable chamber 183 has a higher pressure than the side of the sub-back pressure chamber 182. Then, the valve 192 is separated from the valve seat part 113 of the pilot housing 81, whereby the oil fluid L flows from the lower chamber 20, the lower chamber communication passage 211, and the variable chamber 183 to the sub-back pressure chamber 182 and the pilot chamber 95. In other words, when the lower chamber 20 is under an upstream pressure, the check valve 191 provided in the second passage 202 including the lower chamber communication passage 211 opens and allows the oil fluid L to flow.

[0104] During the compression stroke, when the valve 192 of the check valve 191 is separated from the valve seat portion 113, the valve 192 reduces a flow path cross-sectional area of ​​the passage in the variable orifice 193 between itself and the disc 161 of the throttle disc 78. This acts to restrict the flow of oil fluid L from the lower chamber 20 to the sub-back pressure chamber 182 via the lower chamber communication passage 211, the variable chamber 183, and the check valve 191 in an open state. As a result, a pressure increase of the sub-back pressure chamber 182 is suppressed. At this time, since the communication port 166 is also provided between the sub-back pressure chamber 182 and the main back pressure chamber 181, the communication port 166 suppresses a flow of the oil fluid L from the sub-back pressure chamber 182 to the main back pressure chamber 181.As a result, a pressure increase in the main backpressure chamber 181 is further suppressed compared to the pressure increase in the sub-backpressure chamber 182. Thus, when the lower chamber 20 is at an upstream pressure, the variable orifice 193 provided downstream of the check valve 191 acts to suppress and control the flow of the oil fluid L serving as the working fluid to the sub-backpressure chamber 182 and the main backpressure chamber 181.

[0105] In the piston rod 21, the annular element 226, the disc 225, the disc 224, the plurality of discs 223, the disc 222, the disc 221 and the piston 18 are arranged as shown in Fig. 2, as well as the disc 70, the disc 71, the first damping valve 72, the disc 73, the plurality of discs 74, the plurality of discs 75, the disc 76, the disc 77, the throttle disc 78 and the disc 79, as shown in Fig. 3, are stacked in this order on the shaft step portion 29, with the fixing shaft portion 28 inserted through the interior thereof. Also, the disks 91 and 92 are stacked in this order on the throttle disk 78. In this state, the pilot housing 81, the plurality of disks 83, the disk 85, the disk 86, and the annular member 87 are stacked in this order on the disk 79, with the fixing shaft portion 28 inserted through the interior thereof.

[0106] When the parts from the annular element 226 to the annular element 87 are stacked as described above, as in Fig. 2, a nut 245 is screwed onto the outer screw 31 of the fastening shaft portion 28 of the piston rod 21, which protrudes from the annular element 87. As a result, the parts from the annular element 226 to the annular element 87, with the exception of the Fig. 3 and Fig. 4, are clamped in the axial direction by the discs 91 and 92 shown in Fig. 2 shown shaft step portion 29 of the piston rod 21 and the nut 245 are clamped on the inner peripheral side thereof or in their entirety.

[0107] In this state, the sealing member 152 of the first damping valve 72 is fitted into the cylindrical portion 102 of the pilot housing 81, and the discs 73 to 77 and 79, the throttle disc 78 and the discs 91 and 92 are arranged inside the pilot housing 81, as shown in the Fig. The throttle plate 78 presses parts on an outer peripheral side of the plates 91 and 92 against the outer seat portion 114 of the pilot housing 81 to prevent axial movement, and brings parts on an inner peripheral side of the plates 91 and 92 into contact with the valve seat portion 113 of the pilot housing 81. In this state, the plates 91 and 92 are slightly elastically deformed and come into pressure contact with the valve seat portion 113.

[0108] As in Fig. 1, the above-described bottom valve 25 is provided between the inner cylinder 3 and the bottom part 12 of the outer cylinder 4. The bottom valve 25 includes a bottom valve element 251, a poppet valve 252, a poppet valve 253, and a fixing pin 254. The bottom valve 25 is disposed on the bottom part 12 of the bottom valve element 251 and fitted into the inner cylinder 3. The bottom valve element 251 separates the lower chamber 20 and the reservoir chamber 6. The poppet valve 252 is disposed on a lower side of the bottom valve element 251, that is, on the reservoir chamber 6 side. The poppet valve 253 is disposed on an upper side of the bottom valve element 251, that is, on the lower chamber 20 side. The fixing pin 254 connects the poppet valve 252 and the poppet valve 253 to the base valve member 251.

[0109] The bottom valve element 251 has an annular shape, and the fixing pin 254 is inserted radially through its center. A plurality of through holes 255 and a plurality of through holes 256 are formed in the bottom valve element 251. The plurality of through holes 255 allow the oil fluid L to flow between the lower chamber 20 and the reservoir chamber 6. The plurality of through holes 256 are arranged on an outer side of the plurality of through holes 255 in a radial direction of the bottom valve element 251. The plurality of through holes 256 allow the oil fluid L to flow between the lower chamber 20 and the reservoir chamber 6. The poppet valve 252 on the reservoir chamber 6 side allows the oil fluid L to flow from the lower chamber 20 to the reservoir chamber 6 through the through holes 255.On the other hand, the poppet valve 252 suppresses a flow of the oil fluid L from the reservoir chamber 6 to the lower chamber 20 through the through holes 255. The poppet valve 253 allows a flow of the oil fluid L from the reservoir chamber 6 to the lower chamber 20 through the through holes 256. On the other hand, the poppet valve 253 suppresses a flow of the oil fluid L from the lower chamber 20 to the reservoir chamber 6 through the through holes 256.

[0110] The poppet valve 252, together with the bottom valve element 251, forms a damping valve mechanism 257. The damping valve mechanism 257 opens during the compression stroke of the shock absorber 1, allowing the oil fluid L to flow from the lower chamber 20 into the reservoir chamber 6 and generating a damping force. The poppet valve 253, together with the bottom valve element 251, forms a suction valve mechanism 258. The suction valve mechanism 258 opens during the extension stroke of the shock absorber 1, allowing the oil fluid L to flow from the reservoir chamber 6 into the lower chamber 20. Furthermore, the suction valve mechanism 258 performs the function of causing the fluid to flow from the reservoir chamber 6 into the lower chamber 20, essentially without generating a damping force, thus supplementing a fluid shortage caused primarily by the extension of the piston rod 21 from the cylinder 2.

[0111] A configuration of the damping force generating mechanism 33 described above is shown in a hydraulic circuit diagram in Fig. 6 shown.

[0112] The damping force generating mechanism 33 has the fixed orifice 235, which allows constant communication between the upper chamber 19 and the lower chamber 20. The damping force generating mechanism 33 has the first passage 201, which allows communication between the upper chamber 19 and the lower chamber 20, and the first valve mechanism 41 provided in the first passage 201. The damping force generating mechanism 33 has the second passage 202, which allows communication between the upper chamber 19 and the lower chamber 20 parallel to the first passage 201. The damping force generating mechanism 33 has the inlet port 142 on the lower chamber 20 side of the inlet port 142, and the check valve 191 on the lower chamber 20 side of the pilot chamber 95 in the second passage 202.The damping force generating mechanism 33 includes the second valve mechanism 205 provided in the second passage 202 between the pilot chamber 95 and the lower chamber 20. The damping force generating mechanism 33 includes, in the second passage 202, the variable orifice 193 communicating with the pilot chamber 95, the sub-back pressure chamber 182 communicating with the variable orifice 193, the communication port 166 communicating with the sub-back pressure chamber 182, and the main back pressure chamber 181 communicating with the communication port 166. The damping force generating mechanism 33 has the frequency sensitive mechanism 241 between the sub-back pressure chamber 182 of the second passage 202 and the lower chamber 20. In the damping force generating mechanism 33, the pressure in the main back pressure chamber 181 is applied to the first valve mechanism 41 as back pressure.In the damping force generating mechanism 33, the check valve 191 is locked to the variable orifice 193. The damping force generating mechanism 33 has the first passage 232 that allows communication between the lower chamber 20 and the upper chamber 19, and the first valve mechanism 42 provided in the first passage 232.

[0113] Next, the operation of the shock absorber 1 including the damping force generating mechanism 33 will be described.

[0114] {Low frequency minute low speed range x1 in which the piston frequency is low and the piston speed during the extension stroke is below the first specified value v1}

[0115] In this low-frequency minute low-speed range x1, the first valve mechanism 41 and the second valve mechanism 205 do not open. Then, the oil fluid L flows from the upper chamber 19 into the sub-back pressure chamber 182 of the back pressure chamber 184 via the piston-side passage 43, the passage in the inlet port 142 of the disc 70, and the pilot chamber 95. Then, the valve 192 of the frequency-sensitive mechanism 241 moves to the lower surface side of the annular recessed portion 125. In the low-frequency minute low-speed range x1, since the piston frequency is low and the piston 18 makes a large stroke, a large amount of the oil fluid L is introduced from the upper chamber 19 into the back pressure chamber 184 at the beginning of the stroke.Therefore, the valve 192 of the frequency-sensitive mechanism 241 moves and deforms toward the lower surface side of the annular recessed portion 125 close to the limit value, and after that, it no longer deforms easily (high spring region). On the other hand, in the low-frequency minute low-speed region x1, the oil fluid L flows from the upper chamber 19 into the lower chamber 20 via the fixed orifice 235. Therefore, in the low-frequency minute low-speed region x1, a damping force with an orifice characteristic (where the damping force is substantially proportional to the square of the piston speed) is generated. For this reason, in the low-frequency minute low-speed region x1, the rate of increase of the damping force with respect to an increase in the piston speed is relatively high.

[0116] {Low-frequency low-speed range x2 in which the piston frequency is low and the piston speed during the extension stroke is equal to or higher than the first specified value v1 and lower than the second specified value v2}

[0117] In this low-frequency low-speed range x2, the oil fluid L flows from the upper chamber 19 through the fixed orifice 235 into the upper chamber 19 as in the low-frequency minute low-speed range x1, and largely moves and deforms the valve 192 of the frequency-sensitive mechanism 241 to the lower surface side of the annular recessed portion 125. Thereafter, the oil fluid L from the upper chamber 19 is introduced into the back pressure chamber 184 via the piston-side passage 43, the passage in the inlet port 142 of the disc 70, and the pilot chamber 95 with less probability. In the low-frequency low-speed range x2, the pressure in the back pressure chamber 184 is higher than in the low-frequency minute low-speed range x1.Therefore, in the low-frequency low-speed range x2, the oil fluid L flows from the upper chamber 19 through the piston-side passage 43, the passage in the inlet port 142 of the disc 70, and the pilot chamber 95 into the lower chamber 20 by opening the second damping valve 84 of the second valve mechanism 205. That is, the oil fluid L flows from the upper chamber 19 through the second passage 202 into the lower chamber 20. As a result, a damping force with valve characteristics (where the damping force is substantially proportional to the piston speed) is generated in the low-frequency low-speed range x2. Therefore, in the low-frequency low-speed range x2, the rate of increase of the damping force with respect to the increase in piston speed is lower than in the low-frequency low-speed range x1.In the low-frequency, low-speed range x2, the pressure in the backpressure chamber 184 becomes high because the valve 192 of the frequency-sensitive mechanism 241 moves and deforms close to its limit. Therefore, the first damping valve 72 of the first valve mechanism 41 is subjected to a large biasing force from the backpressure chamber 184, restricting its opening.

[0118] {Low frequency-medium-high speed range x3 in which the piston frequency is low and the piston speed during the extension stroke is equal to or higher than the second predetermined value v2}

[0119] In this low-frequency medium-high speed range x3, the oil fluid L flows from the upper chamber 19 into the upper chamber 19 through the fixed orifice 235, as in the low-frequency minute low-speed range x1, and opens the second damping valve 84 of the second valve mechanism 205 to flow into the lower chamber 20 via the piston-side passage 43, the passage in the inlet port 142 of the disc 70, and the pilot chamber 95. In this way, in the low-frequency medium-high speed range x3, since the oil fluid L flows into the lower chamber 20 through the second passage 202, a pressure increase of the back pressure chamber 184 due to the oil fluid L introduced from the pilot chamber 95 into the back pressure chamber 184 is suppressed.On the other hand, as a force in a valve opening direction applied from the piston-side passage 43 to the first valve mechanism 41 increases, the oil fluid L flows from the upper chamber 19 through the piston-side passage 43 and flows into the lower chamber 20 by opening the first damping valve 72 of the first valve mechanism 41. That is, the oil fluid L flows from the upper chamber 19 through the first passage 201 into the lower chamber 20. Consequently, in the low-frequency medium-high speed range x3, an increase rate of the damping force with respect to the increase in piston speed is smaller than that in the low-frequency low-speed range x2.

[0120] {High-frequency minute low-speed range x4, in which the piston frequency is higher than the low frequency described above and the piston speed during the extension stroke is lower than the third specified value v3}

[0121] In this high-frequency minute low-speed range x4, the first valve mechanism 41 and the second valve mechanism 205 do not open. Then, the oil fluid L flows from the upper chamber 19 into the upper chamber 19 through the fixed orifice 235, as in the low-frequency minute low-speed range x1, and flows into the sub-back pressure chamber 182 of the back pressure chamber 184 via the piston-side passage 43, the passage in the inlet port 142 of the disc 70, and the pilot chamber 95. Then, the valve 192 of the frequency-sensitive mechanism 241 moves and deforms toward the lower surface side of the annular recessed portion 125. In the high-frequency minute low-speed range x4, the piston frequency is high and the stroke of the piston 18 is small. Therefore, an amount of the oil fluid L introduced from the upper chamber 19 into the back pressure chamber 184 is less than that in the low frequency minute low speed range x1.Therefore, the valve 192 of the frequency-sensitive mechanism 241 is likely to deform without deforming close to the limit value (low spring range). As a result, the oil fluid L introduced from the upper chamber 19 into the back pressure chamber 184 can be absorbed by the movement and deformation of the valve 192. Therefore, despite a high damping force increase rate with respect to the piston speed increase, the damping force in the high-frequency, minute-low-speed range x4 is smaller than that in the low-frequency, minute-low-speed range x1, thereby achieving soft characteristics.

[0122] {High frequency range with low, medium and high speed x5 in which the piston frequency is higher than the low frequency described above and the piston speed is equal to or higher than the third predetermined value v3 during the extension stroke}

[0123] In this high-frequency, low-medium-high-speed range x5, the oil fluid L flows from the upper chamber 19 through the fixed orifice 235 into the upper chamber 19 as in the high-frequency, minute-low-speed range x4, and moves and deforms the valve 192 of the frequency-sensitive mechanism 241 to the bottom surface side of the annular recessed portion 125. In the high-frequency, low-medium-high-speed range x5, since the amount of oil L introduced into the back-pressure chamber 184 is small, a pressure increase in the back-pressure chamber 184 is suppressed by the deformation of the valve 192. Therefore, the biasing force from the back-pressure chamber 184 to the first damping valve 72 of the first valve mechanism 41 is reduced, thereby facilitating the opening of the first damping valve 72.As a result, the oil fluid L flows from the upper chamber 19 through the piston-side passage 43 and flows into the lower chamber 20 by opening the first damping valve 72 of the first valve mechanism 41. That is, the oil fluid L flows from the upper chamber 19 through the first passage 201 into 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 with respect to the increase of the piston speed is smaller than in the high-frequency minute-low speed range x4. In addition, in the high-frequency low-medium-high speed range x5, the damping force at the same piston speed is smaller than in the low-frequency low-speed range x2 and the low-frequency medium-high speed range x3, thereby achieving a softer characteristic.Since a pressure increase in the back pressure chamber 184 is suppressed in the high frequency low medium high speed range x5, the second valve mechanism 205 remains in a closed state.

[0124] {Minute low-speed range y1 in which the piston speed during the compression stroke is less than the fourth specified value v4}

[0125] In this minute low-speed range y1, the first valve mechanism 42 and the check valve 191 do not open. Then, the oil fluid L flows from the lower chamber 20 into the upper chamber through the fixed orifice 235. Therefore, in the very low-speed range y1, a damping force with opening characteristics (where the damping force is substantially proportional to the square of the piston speed) is generated. Therefore, in the minute low-speed range y1, the increase in the damping force with respect to an increase in the piston speed is relatively large.

[0126] {Low-speed range y2 in which the piston speed during the compression stroke is equal to or higher than the fourth specified value v4 and lower than the fifth specified value v5}

[0127] In this low-speed range y2, the oil fluid L flows from the lower chamber 20 through the fixed orifice 235 into the upper chamber 19 as in the low-speed range y1. Moreover, in the low-speed range y2, the oil fluid L is introduced from the lower chamber 20 into the variable chamber 183 through the lower chamber communication passage 211, opens the check valve 191, is introduced into the pilot chamber 95, and flows into the upper chamber 19 via the inlet port 142 of the disc 70 and the piston-side passage 43. In the low-speed range y2, the rate of increase of the damping force with respect to the increase of the piston speed is lower than in the minute low-speed range y1.At this time, the valve 192 of the opened check valve 191 reduces the passage in the variable orifice 193 to suppress a pressure increase in the sub-back pressure chamber 182, and the communication orifice 166 also suppresses a pressure increase in the main back pressure chamber 181.

[0128] {Medium-high speed range y3, in which the piston speed during the compression stroke is equal to or higher than the fifth specified value v5}

[0129] In this medium-high speed range y3, the oil fluid L flows from the lower chamber 20 through the fixed orifice 235 into the upper chamber 19 as in the low-speed range y2, and flows into the upper chamber 19 from the lower chamber communication passage 211 via the pilot chamber 95, the inlet port 142, and the piston-side passage 43 by opening the check valve 191. In addition, in the medium-high speed range y3, the oil fluid L flows from the lower chamber 20 through the piston-side passage 44 and flows into the upper chamber 19 by opening the first damping valve 231 of the first valve mechanism 42. As a result, in the medium-high speed range y3, the rate of increase of the damping force with respect to the increase of the piston speed is lower than in the low-speed range y2.Also at this time, the valve 192 of the opened check valve 191 reduces the passage in the variable orifice 193 to suppress a pressure increase in the sub-back pressure chamber 182, and the communication orifice 166 further suppresses a pressure increase in the main back pressure chamber 181.

[0130] Here, the diameter of the dynamic pressure chamber 184 is larger than the diameter of the valve seat portion 53 of the piston 18. The expansion-side first damping valve 72 therefore absorbs pressure from the lower chamber 20 during the compression stroke.

[0131] When the pressure in the lower chamber 20 rises and reaches a predetermined pressure during the compression stroke, the valve 192 of the check valve 191 provided in the pilot housing 81 opens to introduce the pressure into the backpressure chamber 184. This prevents the first damping valve 72 from opening during the compression stroke when a valve closing force due to the backpressure acting on the first damping valve 72 exceeds a valve opening force due to the pressure in the lower chamber 20 acting on an outer peripheral side of the first damping valve 72.

[0132] Furthermore, the shock absorber 1 has a characteristic during the compression stroke in which the damping force characteristic due to the damping valve mechanism 257 is also combined.

[0133] Patent Document 1 described above discloses a shock absorber having a damping force generating mechanism in which a damping force is variable in response to a frequency. In a shock absorber, a damping force generating mechanism is required to operate smoothly. For example, in the shock absorber described in Patent Document 1, a free valve is provided that functions as a check valve during the compression stroke and as a back pressure introduction valve during the extension stroke. In this case, if the back pressure chamber becomes high due to the opening of the check valve during the compression stroke, when the check valve is closed during a stroke reversal from the compression stroke to the extension stroke, the high back pressure in the back pressure chamber may hinder the smooth opening of the damping force generating mechanism, and thereby the damping force may increase.As a result, in a situation where a soft damping force is to be generated during the stroke reversal from the compression stroke to the extension stroke, it becomes difficult to generate a soft damping force.

[0134] The shock absorber 1 of the first embodiment has a first passage 201 through which the oil fluid L serving as the working fluid flows from the upper chamber 19 on one side in the cylinder 2 due to the movement of the piston 18, and a second passage 202 extending parallel to the first passage 201. Furthermore, the shock absorber 1 includes the first valve mechanism 41 provided in the first passage 201 and operating during the extension stroke when the upper chamber 19 is under upstream pressure to allow the damping force to be adjusted by the pressure of the main back pressure chamber 181, and the frequency-sensitive mechanism 241 provided in the second passage 202 and operating when the upper chamber 19 is under upstream pressure to change the volume according to the movement of the valve 192.In addition, the shock absorber 1 includes the check valve 191 provided in the second passage 202 and operating to allow the flow of the oil fluid L when the lower chamber 20 is under upstream pressure. Then, the shock absorber 1 includes the variable orifice 193 provided downstream of the check valve 191 and operating during the compression stroke when the lower chamber 20 is at upstream pressure to control the flow of the oil fluid L to the main back pressure chamber 181. Therefore, even if the check valve 191 is opened during the compression stroke, the flow of the oil fluid L into the main back pressure chamber 181 can be suppressed by the variable orifice 193, and the main back pressure chamber 181 can be prevented from becoming high pressure.Therefore, back pressure of the main back pressure chamber 181, which hinders smooth opening of the first valve mechanism 41, can be suppressed during stroke reversal from the compression stroke to the extension stroke. Therefore, the damping force generating mechanism 33 including the first valve mechanism 41 can operate smoothly. Therefore, in a situation where a soft damping force is to be generated during stroke reversal from the compression stroke to the extension stroke, it is possible to satisfactorily generate a soft damping force.

[0135] Since the valve 192 also functions as a check valve 191, the number of parts of the damping force generating mechanism 33 can be reduced, and the size of the shock absorber 1 can be reduced. Since the number of parts of the damping force generating mechanism 33 can be reduced, the cost and weight of the shock absorber 1 can be reduced.

[0136] In addition, the shock absorber 1 includes the sub-back pressure chamber 182 provided between the variable orifice 193 and the main back pressure chamber 181. Therefore, even when the check valve 191 is opened during the compression stroke, the oil fluid L flows from the variable orifice 193 to the sub-back pressure chamber 182, and the oil fluid L flows from the sub-back pressure chamber 182 to the main back pressure chamber 181. Therefore, the flow of the oil fluid L into the main back pressure chamber 181 can be further suppressed, and high pressure can be further suppressed from developing in the main back pressure chamber 181. As a result, the back pressure of the main back pressure chamber 181, which hinders the smooth opening of the first valve mechanism 41, can be further suppressed during the stroke reversal from the compression stroke to the extension stroke. Therefore, the damping force generating mechanism 33 including the first valve mechanism 41 can be operated even more smoothly.

[0137] Furthermore, in the shock absorber 1, the sub-back pressure chamber 182 communicates with the main back pressure chamber 181 via the communication port 166. Therefore, even if the check valve 191 is opened during the compression stroke, the flow of oil fluid L into the sub-back pressure chamber 182 can be suppressed through the variable orifice 193, and the flow of oil fluid L from the sub-back pressure chamber 182 to the main back pressure chamber 181 can be suppressed through the communication port 166. Therefore, the main back pressure chamber 181, which becomes high pressure, can be further suppressed. As a result, the back pressure of the main back pressure chamber 181, which hinders the smooth opening of the first valve mechanism 41, can be further suppressed during the stroke reversal from the compression stroke to the extension stroke. Therefore, the damping force generating mechanism 33 including the first valve mechanism 41 can operate even more smoothly.

[0138] The damping force generating mechanism 33 of the first embodiment includes the pilot housing 81, the valve 192, and the throttle plate 78. The pilot housing 81 has a bottomed cylindrical shape and forms the back pressure chamber 184, which generates a biasing force in a valve-closing direction on the first damping valve 72 located on the orifice 103 side. The valve 192 is provided in the bottom portion 101 of the pilot housing 81, defines the variable chamber 183 on a side opposite the back pressure chamber 184, and blocks the flow of the oil fluid L from the back pressure chamber 184 to the variable chamber 183. The throttle plate 78 comes into contact with an outer peripheral side of the valve 192 to restrict the opening of the valve 192. Then, the valve 192 has the variable orifice 193 which restricts an inflow of the oil fluid L from the variable chamber 183 to the back pressure chamber 184.As a result, even if the valve 192 is open, the flow of oil fluid L from the variable chamber 183 to the back pressure chamber 184 through the variable orifice 193 can be restricted, and high pressure can be prevented from building up in the back pressure chamber 184. Therefore, the back pressure in the back pressure chamber 184, which hinders the smooth opening of the first valve mechanism 41, can be suppressed during stroke reversal. Therefore, the damping force generating mechanism 33 can operate smoothly.

[0139] The shock absorber 1 and the damping force generating mechanism 33 of the first embodiment may be changed as in the following modified examples 1 and 2. <Modifiziertes Beispiel 1>

[0140] In the shock absorber 1 and the damping force generating mechanism 33 of the first embodiment, the throttle plate 78 is integrated with the plate 161 by welding the plate 162 to the plate 161, but the plate 162 may be integrated with an outer peripheral portion of the plate 91 of the valve 192 on a side opposite to the plate 92 by welding without being welded to the plate 161. In this case, the plate 161 (throttle element) is in contact with the plate 162 integrated with the plate 91 and presses the valve 192 including the plate 162 against the outer seat portion 114 of the pilot housing 81. That is, in this case, the plate 161 comes into contact with the outer peripheral side of the valve 192 including the plate 162 to limit the opening of the valve 192. <Modifiziertes Beispiel 2>

[0141] The disc 162 is positioned radially through the cylindrical portion 102 of the pilot housing 81 without being welded to the disc 161 or the disc 91. In this case, the disc 162 is interposed axially between the disc 161 and the disc 91, and the disc 162 (throttle element) is in contact with the disc 91 to press the valve 192 against the outer seat portion 114 of the pilot housing 81. That is, in this case, the disc 162 comes into contact with the outer peripheral side of the valve 192 to limit the opening of the valve 192. [Second embodiment]

[0142] In the following, a second embodiment will be described mainly with reference to Fig. 7, focusing on the differences from the first embodiment. Furthermore, parts that are the same as those in the first embodiment are denoted by the same terms and the same reference numerals.

[0143] As in Fig. 7, a shock absorber 1A of the second embodiment includes a damping force generating mechanism 33A partially different from the damping force generating mechanism 33, instead of the damping force generating mechanism 33. The damping force generating mechanism 33A includes a throttle plate 78A partially different from the throttle plate 78, instead of the throttle plate 78. The throttle plate 78A includes a plate 161A partially different from the plate 161, instead of the plate 161.

[0144] A notch 171A is formed in the disc 161A on an inner side of a through hole 165 in a radial direction of the disc 161A. The notch 171A penetrates the disc 161A in an axial direction of the disc 161A. The notch 171A has a linear shape extending in a radial direction of the disc 161A. A plurality of notches 171A are formed in the disc 161A at regular intervals in the circumferential direction of the disc 161A. The notch 171A opens into a sub-back pressure chamber 182.

[0145] The damping force generating mechanism 33A includes a valve 192A (movable member) partially different from the valve 192, instead of the valve 192. The valve 192A includes a disc 91A partially different from the disc 91, instead of the disc 91.

[0146] Disc 91A does not have a notch 171 formed in disc 91. Disc 91A has a constant outer diameter over its entire circumference and also a constant inner diameter over its entire circumference. Disc 91A is a common part that has the same shape as disc 92.

[0147] The damping force generating mechanism 33A includes a check valve 191A, which is partially different from the check valve 191, instead of the check valve 191. The check valve 191A differs from the check valve 191 in that it includes the valve 192A instead of the valve 192. In the check valve 191A, the valve 192A operates in the same manner as the valve 192. Therefore, the check valve 191A operates in the same manner as the check valve 191.

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

[0149] The damping force generating mechanism 33A has a variable orifice 193A (first throttle mechanism, first throttle portion) that is partially different from the variable orifice 193. When the check valve 191A opens, the variable orifice 193A reduces a flow path between itself and the disc 161A due to a portion of the valve 192A on a peripheral side approaching the disc 161A of the throttle disc 78A. A portion of the valve 192A on an inner peripheral side and the disc 161A of the throttle disc 78A form the variable orifice 193A. The variable orifice 193A has a smaller flow path cross-sectional area than the flow path cross-sectional area of ​​a connecting orifice 166. The variable orifice 193A is provided between the pilot chamber 95 and the sub-back pressure chamber 182 and changes the flow path between the pilot chamber 95 and the sub-back pressure chamber 182 according to the amount of deformation of the valve 192A.The variable orifice 193A includes the slot 171A of the disc 161A. A passage in the slot 171A of the disc 161A sets the flow path cross-sectional area in the variable orifice 193A to a non-zero minimum value when the disc 91A of the valve 192A comes into contact with the disc 161A of the throttle disc 78A. That is, the slot 171A of the disc 161A performs the same function as the notch 171 of the disc 91. In this way, the valve 192A forms the variable orifice 193A, which limits the flow of oil fluid L from a variable chamber 183 into the secondary backpressure chamber 182. The valve 192A also serves as a check valve 191A. A sub-back pressure chamber 182 is provided between the variable orifice 193A and a main back pressure chamber 181.

[0150] The damping force generating mechanism 33A has a second passage 202A instead of the second passage 202, which is partially different from the second passage 202. The second passage 202A differs from the second passage 202 in that it has the variable opening 193A instead of the variable opening 193.

[0151] In the shock absorber 1A, when the valve 192A of the check valve 191A is separated from the valve seat portion 113 during the compression stroke, the valve 192A reduces a flow path cross-sectional area of ​​a passage in the variable orifice 193A between itself and the disc 161A of the throttle disc 78A. Thereby, a flow of the oil fluid L from the lower chamber 20 to the sub-back pressure chamber 182 via a lower chamber communication passage 211, the variable chamber 183, and the opened check valve 191A is suppressed. As a result, a pressure increase in the sub-back pressure chamber 182 is suppressed. In this way, the variable orifice 193A provided downstream of the check valve 191A suppresses and controls the flow of the oil fluid L serving as the working medium into the sub-back pressure chamber 182 and the main back pressure chamber 181 when the lower chamber 20 is under an upstream pressure.

[0152] A hydraulic circuit diagram of the configuration of the damping force generating mechanism 33A described above is similar to that of the damping force generating mechanism 33 of the first embodiment. That is, in Fig. 6, the second passage 202 corresponds to the second passage 202A, the check valve 191 corresponds to the check valve 191A, the variable orifice 193 corresponds to the variable orifice 193A, and the frequency-sensitive mechanism 241 corresponds to the frequency-sensitive mechanism 241A.

[0153] The shock absorber 1A and the damping force generating mechanism 33A of the second embodiment also include the variable orifice 193A, which functions in the same manner as the variable orifice 193, and therefore achieve the same effects as the shock absorber 1 and the damping force generating mechanism 33 of the first embodiment.

[0154] The shock absorber 1A and the damping force generating mechanism 33A of the second embodiment can be modified as in Modified Example 1 and Modified Example 2 of the first embodiment. That is, a disc 162 can be integrated with an outer peripheral portion of the disc 91A of the valve 192A on a side opposite to the disc 92 by welding, without being welded to the disc 161A. Alternatively, the disc 162 can be positioned in the radial direction by a cylindrical portion 102 of a pilot housing 81 and inserted in the axial direction between the disc 161 and the disc 91A without being welded to the disc 161 or the disc 91A. [Third Embodiment]

[0155] In the following, a third embodiment will be described mainly with reference to the Fig. 8 to 10, focusing on the differences from the first embodiment. Furthermore, parts identical to those of the first embodiment are designated by the same terms and the same reference numerals.

[0156] As in Fig. 8, a shock absorber 1B of the third embodiment includes a damping force generating mechanism 33B partially different from the damping force generating mechanism 33, instead of the damping force generating mechanism 33. The damping force generating mechanism 33B includes a throttle plate 78B partially different from the throttle plate 78, instead of the throttle plate 78. The throttle plate 78B includes a plate 161B partially different from the plate 161, instead of the plate 161.

[0157] The disc 161B has a through-hole 165B partially different from the through-hole 165, instead of the through-hole 165. The through-hole 165B penetrates the disc 161B in an axial direction of the disc 161B. In a radial direction of the disc 161B, the through-hole 165B extends further inward than the through-hole 165. The through-hole 165B opens into a sub-back pressure chamber 182. A plurality of through-holes 165B are provided in the disc 161B at regular intervals in a circumferential direction of the disc 161B. The through-hole 165B, together with a notch 155 of a disc 77, forms a communication hole 166 similar to that of the first embodiment.

[0158] The damping force generating mechanism 33B includes a valve 192B (movable member) partially different from the valve 192, instead of the valve 192. The valve 192B includes a disc 91B partially different from the disc 91, instead of the disc 91.

[0159] Disc 91B does not include the notch 171 formed in disc 91. Disc 91B has a constant outer diameter over its entire circumference and also a constant inner diameter over its entire circumference. Disc 91B is a conventional part having the same shape as disc 92.

[0160] The damping force generating mechanism 33B includes a check valve 191B, which is partially different from the check valve 191, instead of the check valve 191. The check valve 191B differs from the check valve 191 in that it includes the valve 192B instead of the valve 192. In the check valve 191B, the valve 192B operates in the same manner as the valve 192. Therefore, the check valve 191B operates in the same manner as the check valve 191.

[0161] The damping force generating mechanism 33B includes a frequency-sensitive mechanism 241B, which is partially different from the frequency-sensitive mechanism 241, instead of the frequency-sensitive mechanism 241. The frequency-sensitive mechanism 241B differs from the frequency-sensitive mechanism 241 in that it includes the valve 192B instead of the valve 192. In the frequency-sensitive mechanism 241B, the valve 192B operates in the same manner as the valve 192. Therefore, the frequency-sensitive mechanism 241B operates in the same manner as the frequency-sensitive mechanism 241.

[0162] The variable orifice 193 is not provided in the damping force generating mechanism 33B. A passage in the through hole 165B of the disc 161B allows a variable chamber 183 and a pilot chamber 95 to communicate with the sub-back pressure chamber 182 even when the disc 91B of the valve 192B comes into contact with the disc 161B of the throttle disc 78B.

[0163] The damping force generating mechanism 33B includes a pilot housing 81B partially different from the pilot housing 81, instead of the pilot housing 81. The pilot housing 81B has a bottom portion 101B partially different from the bottom portion 101, instead of the bottom portion 101. The bottom portion 101B has a lower main body portion 111B partially different from the lower main body portion 111, instead of the lower main body portion 111. As shown in Fig. 9, only one through hole 121 is provided in the lower main body portion 111B.

[0164] The bottom portion 101B has an outer seat portion 116B, which is partially different from the outer seat portion 116. The outer seat portion 116B includes a connecting seat portion 311B configured to connect the seat component portions 133 to the through hole 121 located at an intermediate position between them in a circumferential direction of the pilot housing 81B. The connecting seat portion 311B is located outside the through hole 121 in a radial direction of the pilot housing 81B. As shown in Fig. 8, in an axial direction of the pilot housing 81B, a distal end surface of the connecting seat portion 311B on a side opposite to the lower main body portion 111B is aligned in position with a distal end surface of an inner seat portion 115 on a side opposite to the lower main body portion 111B and a distal end surface of the seat constituent portion 133 on a side opposite to the lower main body portion 111B.

[0165] A notch 312B is formed in the connecting seat portion 311B, penetrating the connecting seat portion 311B in the radial direction of the pilot housing 81B. The notch 312B is recessed on the lower main body portion 111B side from the distal end surface of the connecting seat portion 311B on a side opposite the lower main body portion 111B. The notch 312B is formed in the pilot housing 81B by embossing. The notch 312B, together with a disk 83 in contact with the outer seat portion 116B, forms an opening 313B.

[0166] As in Fig. 9, a recessed through portion 315B is formed by surrounding two seat components 133 arranged on both sides of the through hole 121 in the circumferential direction of the pilot housing 81B, a portion of the inner seat portion 115 between the seat components 133, and the connecting seat portion 311B. As shown in Fig. As shown in Fig. 8, the recessed passage portion 315B is recessed in an axial direction of the pilot housing 81 from the distal end surface on a protruding side of the inner seat portion 115, the distal end surface on a protruding side of the seat component 133, and the distal end surface of the connecting seat portion 311B. A bottom surface of the recessed passage portion 315B is formed by the lower main body portion 111. The opening 313B opens to the interior of the recessed passage portion 315B and to a lower chamber 20.

[0167] The damping force generating mechanism 33B has a lower chamber communication passage 211B, which is partially different from the lower chamber communication passage 211, instead of the lower chamber communication passage 211. The lower chamber communication passage 211B consists of a passage in the depressed portion 315B and a passage in the through hole 121. The lower chamber communication passage 211B communicates with the lower chamber 20 via the opening 313B.

[0168] The damping force generating mechanism 33B has a second passage 202B instead of the second passage 202, which is partially different from the second passage 202. The second passage 202B differs from the second passage 202 in that it has the lower chamber communication passage 211B instead of the lower chamber communication passage 211, that it has the orifice 313B, and that the variable orifice 193 is not provided therein.

[0169] In the shock absorber 1B, the orifice 313B of the pilot housing 81B suppresses a flow of oil fluid L from the lower chamber 20 to the lower chamber communication passage 211B and the variable chamber 183 during the compression stroke. This suppresses a flow of oil fluid L from the lower chamber 20 to the sub-back pressure chamber 182 via the orifice 313B, the lower chamber communication passage 211B, and the opened check valve 191B. As a result, a pressure increase in the sub-back pressure chamber 182 is suppressed. In this way, when the lower chamber 20 is at an upstream pressure, the orifice 313B provided upstream of the check valve 191B suppresses and controls a flow of the oil fluid L serving as a working fluid to the sub-back pressure chamber 182 and a main back pressure chamber 181.

[0170] A hydraulic circuit diagram of the configuration of the damping force generating mechanism 33B described above is shown in Fig. 10. That is, the check valve 191 corresponds to the check valve 191B, the frequency-sensitive mechanism 241 corresponds to the frequency-sensitive mechanism 241B, and the orifice 313B is provided between the lower chamber communication passage 211B and the lower chamber 20. Furthermore, in the damping force generating mechanism 33B, the second passage 202 corresponds to the second passage 202B, and the variable orifice 193 is not provided in the second passage 202B.

[0171] The shock absorber 1B of the third embodiment includes the orifice 313B, which is provided upstream of the check valve 191B and operates during the compression stroke when the lower chamber 20 is under an upstream pressure to control a flow of the oil fluid L to the main back pressure chamber 181. Therefore, even if the check valve 191 is opened during the compression stroke, the flow of the oil fluid L into the main back pressure chamber 181 through the orifice 313B can be suppressed, and high pressure can be prevented from developing in the main back pressure chamber 181. Therefore, back pressure of the main back pressure chamber 181, which hinders smooth opening of a first valve mechanism 41, can be suppressed during a stroke reversal from the compression stroke to the extension stroke. Therefore, the damping force generating mechanism 33B including the first valve mechanism 41 can operate smoothly.Consequently, in a situation where a soft damping force is to be generated during stroke reversal from the compression stroke to the extension stroke, it is possible to generate a satisfactorily soft damping force.

[0172] Furthermore, the shock absorber 1B includes the sub-back pressure chamber 182 provided between the orifice 313B and the main back pressure chamber 181. Therefore, even when the check valve 191 is opened during the compression stroke, the oil fluid L flows from the orifice 313B to the sub-back pressure chamber 182, and the oil fluid L flows from the sub-back pressure chamber 182 to the main back pressure chamber 181. Therefore, the flow of the oil fluid L into the main back pressure chamber 181 can be further suppressed, and thereby the generation of high pressure in the main back pressure chamber 181 can be further suppressed. As a result, the back pressure of the main back pressure chamber 181, which hinders smooth opening of the first valve mechanism 41, can be further suppressed during a stroke reversal from the compression stroke to the extension stroke. Therefore, the damping force generating mechanism 33B including the first valve mechanism 41 can be operated even more smoothly.

[0173] The shock absorber 1B and the damping force generating mechanism 33B of the third embodiment can be modified as in the first and second modified examples of the first embodiment. That is, a disc 162 can be integrated with an outer peripheral portion of the disc 91B of the valve 192B on a side opposite to the disc 92 by welding, without being welded to the disc 161B. Alternatively, the disc 162 can be positioned in the radial direction by the cylindrical part 102 of the pilot housing 81 and inserted in the axial direction between the disc 161 and the disc 91B without being welded to the disc 161 or the disc 91B. [Further application examples of the first to third embodiments]

[0174] The configurations of the first to third embodiments can all be applied to a damping force generating mechanism with a built-in control valve.

[0175] For example, Fig. 11 and Fig. 12 shows a shock absorber 1C with a built-in control valve type damping mechanism 33C, and an example in which a main configuration of the damping mechanism 33B of the third embodiment is applied to an extension side of a damping mechanism 33C. In addition, parts common to those of the third embodiment are denoted by the same terms and the same reference numerals.

[0176] As in Fig. As shown in Figure 11, the interior of the inner cylinder 3 of the cylinder 2 in the damping mechanism 33C is divided into the upper chamber 19 and the lower chamber 20 by a piston 18C. The damping mechanism 33C includes a housing 401C, a solenoid 402C covered by the housing 401C, and a piston pin portion 403C serving as a shaft member. In the damping force generating mechanism 33C, the housing 401C is connected to a connecting rod 404C. The connecting rod 404C passes through the rod guide 22 (see Fig. 1) and the sealing element 23 (see Fig. 1) and extends outwards from cylinder 2.

[0177] An extension-side damping force generating mechanism 411C is provided on the lower chamber 20 side of the piston 18C, and a compression-side damping force generating mechanism 412C is provided on the upper chamber 19 side of the piston 18C.

[0178] The mechanism 411C for generating the damping force on the extension side is described with reference to Fig. 12 described.

[0179] The oil fluid L, which has passed through an extension-side piston-side passage 43C from the upper chamber 19, enters through the extension-side inlet opening 142 in the disc 70, through an extension-side inlet opening 416C in the piston pin 415C and into an extension-side pilot chamber 95C.

[0180] The extension-side pilot chamber 95C communicates with the backpressure chamber 184 for the extension-side first damping valve 72 via a pilot communication passage 418C in the piston pin 415C and a passage in the through groove 124 in the pilot housing 81B.

[0181] A pilot valve 421C installed in the piston pin 415C receives a valve closing force from a pressure of the solenoid 402C and opens when a valve opening force caused by a biasing force of a spring 422C and a pressure in the pilot chamber 95C exceeds the pressure of the solenoid 402C. When the pilot valve 421C opens, the oil fluid L in the pilot chamber 95C flows through a compression-side inlet port 424C, opens a poppet valve 426C in which a compression-side inlet port 425C is provided, flows through a compression-side piston-side passage 44C, and flows into the lower chamber 20.

[0182] The oil fluid L, which has passed from the upper chamber 19 through the extension-side piston-side passage 43C, passes through the extension-side inlet port 142 provided in the disc 70, passes through the extension-side inlet port 416C provided in the piston pin 415C, and enters the extension-side pilot chamber 95C. Thereafter, the oil fluid L, which has passed through a passage in a through groove 30C provided in the piston pin 415C, is introduced into the sub-back pressure chamber 182 of the back pressure chamber 184 through the passage in the through groove 124 provided in the pilot housing 81B, passes through the throttle plate 78B and the communication port 166 provided in the disc 77, and enters the main back pressure chamber 181 of the back pressure chamber 184.

[0183] The valve 192B provided in the sub-back pressure chamber 182 separates the variable chamber 183 and the sub-back pressure chamber 182, into which the oil fluid L from the lower chamber 20 is introduced via the orifice 313B and the lower chamber communication passage 211B provided in the pilot housing 81B. Furthermore, the valve 192B forms the check valve 191B, which only allows the flow of the oil fluid L from the lower chamber 20 into the back pressure chamber 184 via the orifice 313B and the lower chamber communication passage 211B. During the extension stroke, the check valve 191B is constantly closed to maintain a control pressure in the back pressure chamber 184. When the axial movement of the piston 18C occurs at a high frequency, a displacement amount of the valve 192B becomes small, resulting in low internal pressure in the back pressure chamber 184.Also, when the axial movement of the piston 18C occurs at a low frequency, the displacement amount of the valve 192B becomes large, resulting in high internal pressure in the backpressure chamber 184. Therefore, a valve opening pressure of the first damping valve 72 can be changed according to the frequency. This frequency can be adjusted through the inlet port 142 provided in the disc 70. Furthermore, the valve opening pressure of the first damping valve 72 can be adjusted by a disc stiffness of the first damping valve 72 at high frequencies and by a disc stiffness of the second damping valve 84 at low frequencies. Volume compensation for a movement volume of the valve 192B is performed through the lower chamber communication passage 211B and the orifice 313B in the pilot housing 81B.

[0184] When the oil fluid L in the backpressure chamber 184 reaches a predetermined pressure, it passes through the passage in the through groove 30C, opens the second damping valve 84, and flows into the lower chamber 20. When the first damping valve 72 opens during the extension stroke, the second damping valve 84 opens as described above, allowing the backpressure chamber 184 to communicate with the lower chamber 20. This enables the volumetric balance of the oil fluid L according to the movement volume of the first damping valve 72.

[0185] The diameter of the backpressure chamber 184 is larger than the diameter of the valve seat portion 53 of the piston 18C. The extension-side first damping valve 72 therefore absorbs pressure from the lower chamber 20 during the compression stroke.

[0186] When the pressure in the lower chamber 20 rises and reaches a predetermined pressure during the compression stroke, the valve 192B of the check valve 191B provided in the pilot housing 81B opens to introduce the pressure into the backpressure chamber 184, and a valve closing force caused by the backpressure is applied to the first damping valve 72. When this valve closing force exceeds the valve opening force due to the pressure in the lower chamber 20 acting on the outer peripheral side of the first damping valve 72, the first damping valve 72 can be prevented from opening during the compression stroke.

[0187] The damping force generating mechanism on the compression side 412C is described.

[0188] The oil fluid L, which has passed from the lower chamber 20 through the compression-side piston-side passage 44C, enters through the compression-side inlet port 425C provided in the poppet valve 426C and into a passage in a compression-side through groove 431C.

[0189] The passage in the compression-side through groove 431C communicates with a back pressure chamber 442C for a compression-side first damping valve 441C via an opening 455C of a check valve 451C in a pilot housing 432C.

[0190] The pilot valve 421C installed in the piston pin 415C receives a valve closing force from the pressure of the solenoid 402C and opens when the valve opening force caused by the spring 422C and the pressure in the pilot chamber 95C exceeds the pressure of the solenoid 402C. When the pilot valve 421C opens, the oil fluid L that has entered the passage in the through groove 431C flows from the compression-side inlet port 424C through the extension-side pilot chamber 95C, opens the disc 70 in which the extension-side inlet port 142 is provided, and flows through the extension-side piston-side passage 43C to flow into the upper chamber 19.

[0191] The check valve 451C, which only allows the flow of oil fluid L from the upper chamber 19 to the back pressure chamber 442C, and a connecting passage 452C to the upper chamber are provided inside the pilot housing 432C, and the orifice 455C is provided on an inner peripheral side of the check valve 451C. During the compression stroke, the check valve 451C is constantly closed to maintain a control pressure in the back pressure chamber 442C.

[0192] When the first damping valve 441C opens during the compression stroke, the back pressure chamber 442C communicates with the upper chamber 19 via the opening 455C and the passage in the through groove 431C, thereby enabling the volume equalization of the oil fluid L corresponding to a movement volume of the first damping valve 441C.

[0193] A second damping valve 461C, an inner circumferential groove 462C, and a relief communication passage 463C for relieving the pressure in the back pressure chamber 442C, which has reached a predetermined pressure, to the upper chamber 19 are provided at a lower portion of the pilot housing 432C in which the compression-side first damping valve 441C is installed.

[0194] The seat of the second damping valve 461C is a non-standard seat that separates the relief connection passage 463C and the upper chamber passage 452C. The amount of back pressure introduced can be adjusted by a notch 465C provided in the seat.

[0195] Here, since a diameter of the back pressure chamber 442C of the first damping valve 441C is larger than a diameter of the valve seat portion 57 of the piston 18C, the compression-side first damping valve 441C receives the pressure of the upper chamber 19 during the extension stroke.

[0196] When the pressure in the upper chamber 19 increases and reaches a predetermined pressure during the extension stroke, the check valve 451C opens to introduce the pressure into the back pressure chamber 442C, thereby exerting a valve closing force due to the back pressure on the first damping valve 441C. When the valve closing force exceeds a valve opening force due to the pressure in the upper chamber 19 acting on an outer peripheral side of the first damping valve 441C, the first damping valve 441C can be prevented from opening during the extension stroke. INDUSTRIAL APPLICABILITY

[0197] According to the above-described embodiments of the present invention, it is possible to provide a shock absorber and a damping force generating mechanism that enable smooth operation of the damping force generating mechanism. Therefore, industrial applicability is high. REFERENCE SYMBOL LIST 1, 1A, 1B, 1C shock absorbers 2 cylinders 18 pistons 19 Upper chamber (first cylinder chamber) 20 Lower chamber (second cylinder chamber) 41 First valve mechanism (valve mechanism) 72 First damping valve (damping force generating element) 78, 78A, 78B throttle disc (throttle element) 81 Pilot housing (element for generating the preload force) 101 floor section 166 Communication opening (second throttle mechanism) 181 Main backpressure chamber 182 Secondary backpressure chamber 183 Variable Chamber 184 Backpressure chamber 191, 191A, 191B check valve 192, 192A, 192B Valve (movable element) 193, 193A Variable opening (first throttle mechanism, first throttle section) 201 First Round 202 Second Round 241, 241, 241B Frequency-dependent mechanism 313B Opening (first throttle mechanism, first throttle section) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-55850 A

[0003]

Claims

[1] Shock absorber, comprising: a cylinder in which a working fluid is enclosed; a piston slidably fitted into the cylinder and dividing the interior of the cylinder into first and second cylinder spaces; a first passage through which the working fluid flows from a chamber into the cylinder due to the movement of the piston; a second passage running parallel to the first passage; a valve mechanism provided in the first passage and operating when the first cylinder chamber is under an upstream pressure to allow adjustment of the damping force by a pressure in a main back pressure chamber; a frequency-sensitive mechanism provided in the second passage and operating when the first cylinder chamber is under an upstream pressure to change a volume according to the movement of a movable member; a check valve provided in the second passage and operating when the second cylinder chamber is under an upstream pressure; and a first throttle mechanism provided downstream or upstream of the check valve and operating when the second cylinder chamber is under an upstream pressure to control a flow of the working fluid to the main back pressure chamber. [2] Shock absorber according to claim 1, wherein the movable member also serves as a check valve. [3] A shock absorber according to claim 1 or 2, wherein a sub-back pressure chamber is provided between the first throttle mechanism and the main back pressure chamber. [4] Shock absorber according to claim 3, characterized by that the secondary backpressure chamber is connected to the main backpressure chamber via a second throttle mechanism. [5] Damping force generating mechanism comprising: a biasing force generating member having a bottomed cylindrical shape and forming a back pressure chamber that generates a biasing force in a valve closing direction to a damping force generating member disposed on an opening side; a valve provided at a bottom portion of the biasing force generating member, defining a variable chamber on a side opposite to the back pressure chamber, and blocking a flow of a working fluid from the back pressure chamber to the variable chamber; and a throttle element that comes into contact with an outer peripheral side of the valve to limit the opening of the valve, wherein the valve has a first throttle section which limits the flow of the working fluid from the variable chamber to the backpressure chamber.