JP2020016288A - Shock absorber - Google Patents

Abstract

To provide a shock absorber which enables smoothing of damping force characteristics.SOLUTION: A shock absorber includes: a first damping force generation mechanism 41 which generates damping force with a first passage 130; a housing 56 in which a second passage 140 is formed; and a partition disc 69 which forms a housing inner chamber 102 with a bottom part 71 of the housing 56. The first damping force generation mechanism 41 includes: a first main valve 121; and a first pilot chamber 401 in which pressure is exerted on the first main valve 121 in a valve closing direction. The shock absorber is provided with a second damping force generation mechanism 441 which inhibits flow of a working fluid from the first pilot chamber 401 to a downstream chamber 20 to generate the damping force. The second damping force generation mechanism 441 includes: a second main valve 52 which inhibits flow of the working fluid from the first pilot chamber 401 to the downstream chamber 20; and a second pilot chamber 101 in which pressure is exerted on the second main valve 52 in the valve closing direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a shock absorber.

  Some shock absorbers have a variable damping force in response to frequency (for example, see Patent Document 1).

WO 2017/047661

  In a shock absorber, it is required to make damping force characteristics smooth.

  Therefore, an object of the present invention is to provide a shock absorber that can make damping force characteristics smooth.

  In order to achieve the above object, one embodiment of the present invention provides a first passage through which a working fluid flows out of one chamber in a cylinder by movement of a piston, a second passage provided in parallel with the first passage, A first damping force generating mechanism provided in the first passage for generating a damping force, a bottomed cylindrical housing in which at least a part of the second passage is formed, and movable with respect to the housing And a disk forming a housing inner chamber between itself and the bottom of the housing, wherein the first damping force generating mechanism is configured to transfer the working fluid from the upstream chamber to the downstream chamber by sliding the piston. A first main valve configured to generate a damping force by suppressing a flow; and a first pilot chamber configured to apply pressure to the first main valve in a valve closing direction. Working fluid A second damping force generating mechanism that suppresses the flow to generate a damping force is provided, and the second damping force generating mechanism suppresses the flow of the working fluid from the first pilot chamber to the downstream chamber to reduce the damping force. And a second pilot chamber for applying pressure to the second main valve in a valve closing direction.

  According to another aspect of the present invention, a first passage through which a working fluid flows out of one chamber in a cylinder by movement of a piston, a second passage provided in parallel with the first passage, and a first passage provided in the first passage. A damping force generating mechanism for generating a damping force, a bottomed cylindrical housing in which at least a part of the second passage is formed, and a bottom portion of the housing movably provided with respect to the housing. A disk forming a housing inner chamber therebetween, wherein the damping force generating mechanism suppresses the flow of the working fluid from the upstream chamber to the downstream chamber by sliding the piston to generate a damping force. And a pilot chamber for applying pressure to the main valve in a valve closing direction, wherein the cylindrical portion of the housing has a tapered shape in which the inner diameter increases as the distance from the bottom toward the disk increases.

  According to the present invention, it is possible to make damping force characteristics smooth.

It is a sectional view showing the shock absorber of a 1st embodiment concerning the present invention. It is a fragmentary sectional view showing the circumference of the piston of the buffer of a 1st embodiment concerning the present invention. It is a one side sectional view showing an important section of a buffer of a 1st embodiment concerning the present invention. It is a hydraulic circuit diagram of a shock absorber of a first embodiment according to the present invention. FIG. 4 is a characteristic diagram illustrating damping force characteristics of the shock absorber according to the first embodiment of the present invention. It is a half sectional view showing an important section of a shock absorber of a 2nd embodiment concerning the present invention. It is a one side sectional view showing the circumference of a frequency response part of a buffer of a 2nd embodiment concerning the present invention. It is a characteristic diagram with respect to the pressure load of the tension force which the cylinder part of the case member of the shock absorber of 2nd Embodiment concerning this invention receives from the sealing part of a division disk. It is a half sectional view showing an important section of a shock absorber of a 3rd embodiment concerning the present invention.

[First Embodiment]
A first embodiment according to the present invention will be described with reference to FIGS. In the following, for convenience of description, the upper side in the drawings is described as “upper”, and the lower side in the drawings is described as “lower”.

  As shown in FIG. 1, the shock absorber 1 of the first embodiment is a so-called double-cylinder hydraulic shock absorber, and includes a cylinder 2 in which an oil liquid (not shown) as a working fluid is sealed. The cylinder 2 includes a cylindrical inner cylinder 3, a bottomed cylindrical outer cylinder 4 having a diameter larger than the inner cylinder 3 and provided concentrically to cover the inner cylinder 3, and an upper opening of the outer cylinder 4. A cover 5 is provided so as to cover the side, and a reservoir chamber 6 is formed between the inner cylinder 3 and the outer cylinder 4.

  The outer cylinder 4 includes a cylindrical body member 11 and a bottom member 12 which is fitted and fixed to a lower side of the body member 11 and closes a lower portion of the body member 11. A mounting eye 13 is fixed to the bottom member 12 on the outer side opposite to the body member 11.

  The cover 5 has a tubular portion 15 and an inner flange portion 16 extending radially inward from the upper end side of the tubular portion 15. The cover 5 is covered on the body member 11 such that the upper end opening of the body member 11 is covered with the inner flange portion 16 and the outer peripheral surface of the body member 11 is covered with the cylindrical portion 15. Are caulked inward in the radial direction and are fixed to the body member 11.

  The shock absorber 1 includes a piston 18 slidably provided inside the inner cylinder 3 of the cylinder 2. The piston 18 defines two chambers in the inner cylinder 3, an upper chamber 19 as one cylinder inner chamber and a lower chamber 20 as the other cylinder inner chamber. An oil liquid as a working fluid is sealed in the upper chamber 19 and the lower chamber 20 in the inner cylinder 3, and an oil liquid and a gas as a working fluid are filled in the reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4. And are enclosed.

  The shock absorber 1 includes a piston rod 21 whose one end portion is disposed inside the inner cylinder 3 of the cylinder 2 and is connected and fixed to the piston 18, and whose other end portion protrudes outside the cylinder 2. The piston rod 21 penetrates through the upper chamber 19 and does not penetrate the lower chamber 20. Therefore, the upper chamber 19 is a rod-side chamber through which the piston rod 21 passes, and the lower chamber 20 is a bottom-side chamber on the bottom side of the cylinder 2.

  The piston 18 and the piston rod 21 move integrally. In the extension stroke of the shock absorber 1 in which the piston rod 21 increases the protrusion amount from the cylinder 2, the piston 18 moves to the upper chamber 19 side, and the piston rod 21 reduces the protrusion amount of the shock absorber 1 from the cylinder 2. During the contraction stroke, the piston 18 moves to the lower chamber 20 side.

  A rod guide 22 is fitted to the upper end opening side of the inner cylinder 3 and the outer cylinder 4, and a seal member 23 is attached to the outer cylinder 4 above the rod guide 22 on the outer side of the cylinder 2. I have. A friction member 24 is provided between the rod guide 22 and the seal member 23. The rod guide 22, the seal member 23, and the friction member 24 are all annular, and the piston rod 21 is slidably inserted into each of the rod guide 22, the friction member 24, and the seal member 23. The cylinder 2 extends from the inside to the outside. One end of the piston rod 21 is fixed to the piston 18 inside the cylinder 2, and the other end protrudes outside the cylinder 2 via a rod guide 22, a friction member 24 and a seal member 23.

  The rod guide 22 guides the movement of the piston rod 21 by supporting the piston rod 21 so as to be movable in the axial direction while restricting the movement in the radial direction. The seal member 23 is in close contact with the outer cylinder 4 at its outer peripheral portion, and is slidably contacted at its inner peripheral portion with the outer peripheral portion of the piston rod 21 that moves in the axial direction. This prevents the high-pressure gas and oil liquid in the reservoir chamber 6 from leaking to the outside. The friction member 24 slidably contacts an outer peripheral portion of the piston rod 21 at an inner peripheral portion thereof to generate frictional resistance on the piston rod 21. The friction member 24 is not intended for sealing.

  The outer periphery of the rod guide 22 has a stepped shape in which the upper part has a larger diameter than the lower part. The rod guide 22 fits into the inner peripheral part of the upper end of the inner cylinder 3 at the lower part of the small diameter and the outer cylinder at the upper part of the large diameter. 4 is fitted to the upper inner peripheral portion. A base valve 25 that defines the lower chamber 20 and the reservoir chamber 6 is installed on the bottom member 12 of the outer cylinder 4, and the inner peripheral portion at the lower end of the inner cylinder 3 is fitted to the base valve 25. ing. A part (not shown) of the upper end of the outer cylinder 4 is swaged radially inward, and the swaged part and the rod guide 22 sandwich the seal member 23.

  The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28 having a smaller diameter. The main shaft 27 of the piston rod 21 is slidably fitted to the rod guide 22, the seal member 23, and the friction member 24, and the mounting shaft 28 is disposed in the cylinder 2 and connected to the piston 18 and the like. . An end portion of the main shaft portion 27 on the side of the mounting shaft portion 28 is a shaft step portion 29 which spreads in a direction perpendicular to the shaft. A passage groove 30 extending in the axial direction is formed in an outer peripheral portion of the mounting shaft portion 28 at an intermediate position in the axial direction, and a male screw 31 is formed at a distal end position opposite to the main shaft portion 27 in the axial direction. ing. A plurality of passage grooves 30 are formed at intervals in the circumferential direction of the mounting shaft portion 28, and have a rectangular, square, or D-shaped cross section in a plane orthogonal to the central axis of the piston rod 21. It is formed so as to form.

  The piston rod 21 is provided with a ring-shaped stopper member 32 and a cushioning member 33 in a portion between the piston 18 of the main shaft portion 27 and the rod guide 22. The stopper member 32 has the piston rod 21 inserted through the inner peripheral side, and is caulked and fixed in a fixing groove 34 that is recessed inward in the radial direction of the main shaft portion 27. The buffer body 33 also has the piston rod 21 inserted therein, and is disposed between the stopper member 32 and the rod guide 22.

  In the shock absorber 1, for example, a protruding portion of the piston rod 21 from the cylinder 2 is disposed at an upper portion and supported by a vehicle body, and a mounting eye 13 on the cylinder 2 side is disposed at a lower portion and connected to a wheel side. Conversely, the cylinder 2 side may be supported by the vehicle body, and the piston rod 21 may be connected to the wheel side. When the wheels vibrate as the vehicle travels, the positions of the cylinder 2 and the piston rod 21 relatively change with the vibration. The change is caused by the flow path formed in at least one of the piston 18 and the piston rod 21. Is suppressed by the fluid resistance. As described in detail below, the fluid resistance of the flow path formed in at least one of the piston 18 and the piston rod 21 is made different depending on the speed and amplitude of the vibration. Is improved. Between the cylinder 2 and the piston rod 21, in addition to the vibration generated by the wheels, an inertial force and a centrifugal force generated in the vehicle body as the vehicle travels also act. For example, a centrifugal force is generated in the vehicle body by changing the traveling direction by operating the steering wheel, and 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 good characteristics with respect to vibration based on a force generated in the vehicle body as the vehicle travels, and high stability in traveling the vehicle is obtained.

  As shown in FIG. 2, the piston 18 is composed of a metal piston body 35 supported by the piston rod 21 and an annular composite body that is integrally mounted on the outer peripheral surface of the piston body 35 and slides inside the inner cylinder 3. And a sliding member 36 made of resin.

  The piston body 35 has a plurality of passage holes 37 for communicating the upper chamber 19 and the lower chamber 20 (only one passage hole is shown in FIG. 2 because of the cross section), and a plurality of passage holes 37 for communicating the upper chamber 19 and the lower chamber 20. (Only one location is shown in FIG. 2 because of the cross-section). The plurality of passage holes 37 are formed at an equal pitch with one passage hole 39 interposed therebetween in the circumferential direction of the piston body 35, and constitute half of the passage holes 37, 39. The plurality of passage holes 37 are open radially outward on one axial side (upper side in FIG. 2) of the piston 18 and radially inward on the other axial side (lower side in FIG. 2).

  The passage portion 38 in the passage hole 37 is provided with a damping force generation mechanism 41 (first damping force generation mechanism) that opens and closes the passage portion 38 to generate a damping force. The damping force generating mechanism 41 is disposed on the lower chamber 20 side, which is one end side of the piston 18 in the axial direction, and is attached to the piston rod 21. Since the damping force generating mechanism 41 is disposed on the lower chamber 20 side, the plurality of passages 38 move to the upper chamber 19 side of the piston 18, that is, the upper chamber 19 (upstream chamber) which is on the upstream side in the extension stroke. This is a passage through which an oil liquid as a working fluid flows toward the lower chamber 20 (downstream chamber) on the downstream side. The damping force generation mechanism 41 provided for these passage portions 38 suppresses the flow of the oil liquid from the expansion side passage portion 38 to the lower chamber 20 and generates a damping force. It has become.

  The other half of the passage holes 39 shown in FIG. 2 are formed at a constant pitch in the circumferential direction with one passage hole 37 interposed therebetween, and the other side in the axial direction of the piston 18 (FIG. 2). (The lower side) opens radially outward and one side in the axial direction (the upper side in FIG. 2) opens radially inward.

  The passage portion 40 in the passage hole 39 is provided with a damping force generation mechanism 42 that opens and closes the passage portion 40 to generate a damping force. The damping force generating mechanism 42 is disposed on the upper chamber 19 side, which is the other end of the piston 18 in the axial direction, and is attached to the piston rod 21. Since the damping force generating mechanism 42 is disposed on the upper chamber 19 side, the plurality of passages 40 move to the lower chamber 20 side of the piston 18, that is, from the lower chamber 20 which is on the upstream side in the contraction stroke to the downstream side. A passage through which the oil liquid flows toward the upper chamber 19. The damping force generating mechanism 42 provided for these passage portions 40 suppresses the flow of the oil liquid from the contracting side passage portion 40 to the upper chamber 19 and generates a damping force. It has become.

  As described above, the passage portion 38 in the plurality of passage holes 37 and the passage portion 40 in the plurality of passage holes 39 cause the movement of the piston 18 so that the oil liquid as the working fluid flows between the upper chamber 19 and the lower chamber 20. When the piston rod 21 and the piston 18 move to the extension side (the upper side in FIG. 2), the oil liquid passes through the passage 38, and the passage 40 communicates with the piston rod 21 and the piston The oil liquid passes when 18 moves to the contraction side (the lower side in FIG. 2).

  The piston main body 35 has a substantially disk shape, and an insertion hole 44 is formed in the center in the radial direction so as to penetrate in the axial direction to allow the mounting shaft portion 28 of the piston rod 21 to pass therethrough. . The insertion hole 44 has a small-diameter hole 45 on one side in the axial direction in which the mounting shaft 28 of the piston rod 21 is fitted, and a large-diameter hole 46 on the other side in the axial direction having a diameter larger than the small-diameter hole 45. are doing.

  An annular valve seat portion that constitutes a part of the damping force generating mechanism 41 is provided at an end of the piston body 35 on the axial side of the lower chamber 20, radially outside the opening of the passage hole 37 on the lower chamber 20 side. 47 are formed. In the insertion hole 44, the large-diameter hole 46 is provided closer to the valve seat 47 in the axial direction than the small-diameter hole 45. An annular valve that constitutes a part of the damping force generating mechanism 42 is provided at an end of the piston body 35 on the upper chamber 19 side in the axial direction, radially outside the opening of the passage hole 39 on the upper chamber 19 side. A seat portion 48 is formed.

  In the piston body 35, the side opposite to the insertion hole 44 of the valve seat portion 47 has a stepped shape having a lower height in the axial direction than the valve seat portion 47, and the stepped portion has a passage hole 39 on the contracted side. An opening on the lower chamber 20 side of the inner passage portion 40 is arranged. Similarly, in the piston body 35, the side opposite to the insertion hole 44 of the valve seat portion 48 has a stepped shape whose height in the axial direction is lower than that of the valve seat portion 48, and extends to this stepped portion. An opening on the upper chamber 19 side of the passage portion 38 in the side passage hole 37 is disposed.

  As shown in FIG. 3, one disc 50, one disc 51, one pilot valve 352, and one disc 50 are arranged on the valve seat 47 side of the piston 18 in order from the piston 18 side in the axial direction. One disk 353, one disk 355, one case member 356, one pilot valve 52 (second main valve), a plurality of disks 53, one spring disk 54, one disk One disk 55, one case member 56 (housing), a plurality of disks 57, one disk 58, one disk 59, and one annular member 60 are attached to the piston rod 21. The shaft portions 28 are provided so as to be fitted inside the respective shaft portions. The disks 50, 51, 53, 55, 57 to 59, 353, 355, the spring disk 54, the case members 56, 356, and the annular member 60 are all made of metal. Each of the discs 50, 51, 53, 55, 57 to 59, 353, 355 and the annular member 60 has a circular flat plate with a fixed thickness to which the mounting shaft 28 of the piston rod 21 can be fitted. ing. Each of the spring disk 54, the pilot valves 52 and 352, and the case members 56 and 356 has an annular shape in which the mounting shaft 28 of the piston rod 21 can be fitted.

  The case member 356 has a bottomed cylindrical shape and is annular, and has a perforated disk-shaped bottom portion 371 in which a through hole 370 penetrating in the thickness direction is formed at the center in the radial direction, and an inner peripheral edge of the bottom portion 371. A cylindrical inner cylindrical portion 372 projecting to both sides along the axial direction of the bottom portion 371; and a cylindrical outer cylindrical portion projecting from the outer peripheral edge of the bottom portion 371 to one side along the axial direction of the bottom portion 371. 373, and an annular valve seat portion 374 that protrudes from an intermediate position in the radial direction of the bottom portion 371 along the axial direction of the bottom portion 371 to the side opposite to the outer cylindrical portion 373. The mounting shaft 28 of the piston rod 21 passes through the through hole 370 of the case member 356. The bottom part 371, the inner cylindrical part 372, the outer cylindrical part 373, and the valve seat part 374 are coaxially arranged, and their central axes are the central axes of the case member 356.

  In the bottom portion 371, a through hole 367 penetrating along the axial direction of the bottom portion 371 is formed between the outer cylindrical portion 373 and the valve seat portion 374 in the radial direction and the inner cylindrical portion 372. A plurality of through holes 367 are formed in the bottom 371 at intervals in the circumferential direction of the bottom 371 (only one portion is shown in FIG. 3 because of a partial cross section). Note that at least one through hole 367 may be provided in the bottom 371.

  In the through hole 370 on the inner periphery of the inner cylindrical portion 372, a small-diameter hole portion 375 for fitting the mounting shaft portion 28 of the piston rod 21 is formed on the valve seat portion 374 side in the axial direction. A large-diameter hole 376 having a diameter larger than that of the small-diameter hole 375 is formed on the side opposite to the sheet portion 374. A part of the mounting shaft 28 of the piston rod 21 inserted into the through hole 370 is disposed in the case member 356 in the axial direction. The inside of the large-diameter hole portion 46 of the piston main body 35, the inside of the passage groove 30 of the mounting shaft portion 28, and the inside of the large-diameter hole portion 376 of the case member 356 always communicate with each other. I have.

  The disk 50 has an outer diameter smaller than the inner diameter of the valve seat portion 47. A notch 81 is formed in the disc 50 and extends radially outward from an inner peripheral edge of the disc 50 that is fitted to the mounting shaft 28 of the piston rod 21. The passage 82 in the notch 81 is always in communication with the passage 38 of the piston 18 on the one hand, and is always in communication with the intermediate chamber 85 on the other hand. The passage portion 82 in the notch 81 is a throttle, that is, an orifice provided between the upper chamber 19 and the intermediate chamber 85 which are always in communication with the passage portion 38.

  The disk 51 has an outer diameter substantially equal to the outer diameter of the valve seat portion 47 of the piston 18. The disc 51 is in contact with the valve seat portion 47, and opens and closes the opening of the passage portion 38 formed in the piston 18 by separating and contacting the valve seat portion 47. A notch 91 is formed on the outer peripheral side of the disk 51, and the notch 91 traverses the valve seat portion 47 in the radial direction. Therefore, the inside of the notch 91 is a fixed orifice 92 that constantly connects the passage 38 to the lower chamber 20.

  The pilot valve 352 includes a metal disk 395 and a rubber seal member 396 fixed to the disk 395. The disk 395 has a circular flat plate shape with a certain thickness, into which the mounting shaft portion 28 of the piston rod 21 can be fitted, and has an outer diameter slightly larger than the outer diameter of the disk 51. . The seal member 396 is fixed to the outer peripheral side of the disk 395 opposite to the piston 18 in the axial direction, and has an annular shape. In other words, the pilot valve 352 has an annular seal member 396 on the outer periphery.

  The seal member 396 is slidably and liquid-tightly fitted to the inner peripheral surface of the outer cylindrical portion 373 of the case member 356 over the entire circumference, and always keeps the gap between the pilot valve 352 and the outer cylindrical portion 373 constant. Seal. In other words, pilot valve 352 has seal member 396 slidably and tightly fitted to outer cylindrical portion 373 of case member 356.

  A space between the pilot valve 352, the case member 356, and a pilot valve 52 to be described later is a pilot chamber 401 (first pilot chamber) serving as a back pressure chamber of the pilot valve 352. Pilot chamber 401 includes a passage 403 in through hole 367. The valve seat portion 374 surrounds an opening of the pilot chamber 401 on the side opposite to the piston 18.

  The disk 353 has an outer diameter smaller than the minimum inner diameter of the seal member 396 of the pilot valve 352. The outer diameter of the disk 353 is equal to the outer diameter of the distal end surface of the inner cylindrical portion 372 of the case member 356, and is larger than the inner diameter of the large-diameter hole 376.

  The disk 355 has an outer diameter smaller than the minimum inner diameter of the seal member 396 of the pilot valve 352. The outer diameter of the disk 355 is larger than the outer diameter of the distal end surface of the inner cylindrical portion 372 of the case member 356. The disc 355 has a notch 415 extending radially outward from an inner peripheral edge of the disc 355 fitted to the mounting shaft 28 of the piston rod 21. The passage 416 in the notch 415 is always in communication with the pilot chamber 401 on the one hand, and is always in communication with the intermediate chamber 85 on the other hand. Therefore, the pilot chamber 401 is always in communication with the intermediate chamber 85 via the passage 416 in the notch 415. The passage 416 in the notch 415 is a throttle provided between the pilot chamber 401 and the intermediate chamber 85, that is, an orifice. The pilot chamber 401 is always in communication with the upper chamber 19 via the passage 416 of the disc 355, the intermediate chamber 85, the passage 82 of the disc 50, and the passage 38 of the piston 18.

  The case member 56 has a bottomed cylindrical shape and is annular, and has a perforated disc-shaped bottom 71 in which a through hole 70 penetrating in the thickness direction is formed at the center in the radial direction, and an inner peripheral edge of the bottom 71, A cylindrical inner cylindrical portion 72 projecting to both sides along the axial direction of the bottom portion 71; and a cylindrical outer cylindrical portion projecting from the outer peripheral edge of the bottom portion 71 to one side along the axial direction of the bottom portion 71. 73, and an annular valve seat portion 74 protruding from an intermediate position in the radial direction of the bottom portion 71 along the axial direction of the bottom portion 71 to the side opposite to the outer cylindrical portion 73. The mounting shaft 28 of the piston rod 21 passes through the through hole 70 of the case member 56. The bottom portion 71, the inner cylindrical portion 72, the outer cylindrical portion 73, and the valve seat portion 74 are coaxially arranged, and their central axes are the central axes of the case member 56.

  The bottom portion 71 has a flat annular seat surface 61 perpendicular to the central axis of the bottom portion 71 on the outer cylindrical portion 73 side in the axial direction and on the outer cylindrical portion 73 side in the radial direction. A contact portion 62 is formed. An annular recess 64 having a stopper surface 63 that is recessed in the axial direction from the seat surface 61 is formed at a radially intermediate position of the disk contact portion 62. The concave portion 64 has such a shape that the radial width decreases as the depth increases. The cross section of the stopper surface 63 on the plane including the central axis of the bottom 71 has a constant arc shape regardless of the circumferential position.

  The bottom portion 71 has a taper surface 65 having a taper surface 65 on the side of the outer cylindrical portion 73 in the axial direction and inside the disk contact portion 62 in the radial direction, and the height from the seat surface 61 becomes higher toward the inner side in the radial direction. A part 66 is formed. The tapered portion 66 is provided at an end of the bottom portion 71 on the inner cylindrical portion 72 side in the radial direction. The disk contact portion 62, the concave portion 64, and the tapered portion 66 are arranged coaxially with the center axis of the case member 56.

  A through hole 67 is formed in the bottom 71 at the deepest position of the recess 64, that is, at the center of the radial width of the recess 64 along the axial direction of the bottom 71. A plurality of through holes 67 are formed in the bottom portion 71 at intervals in the circumferential direction of the bottom portion 71 (only one location is shown in FIG. 3 because of a partial cross section). It is sufficient that at least one through hole 67 is provided in the bottom 71. The through hole 67 is arranged outside the valve seat 74 in the radial direction of the bottom 71. The passage 103 in the through hole 67 is always in communication with the lower chamber 20.

  An annular partition disk 69 (disk) is arranged in the case member 56 so as to face the bottom 71. The partition disk 69 is a metal flat plate, and its outer diameter is slightly smaller than the maximum diameter of the sheet surface 61 of the disk contact portion 62, in other words, the maximum diameter of the stopper surface 63 is slightly smaller than the inner diameter of the outer cylindrical portion 73. The diameter is slightly larger than the minimum diameter of the sheet surface 61 of the disk contact portion 62 and smaller than the minimum diameter of the stopper surface 63. As a result, the partition disk 69 is guided by the outer cylindrical portion 73 so as to be restricted from moving in the radial direction with respect to the case member 56, and is movable in the axial direction. , And covers the entire stopper surface 63. The mounting shaft 28 of the piston rod 21 also penetrates the partition disk 69.

  The through hole 67 formed at the deepest position of the concave portion 64 of the bottom portion 71 is provided so as to be radially aligned with the partition disk 69 and opposed in the axial direction. The partition disk 69 closes the through hole 67 by making surface contact with the seat surface 61, and opens the through hole 67 by moving away from the seat surface 61. Further, the partition disk 69 is elastically deformable so as to enter the concave portion 64, and at this time, the partition disk 69 comes into contact with the boundary peripheral portions on both sides in the radial direction between the stopper surface 63 and the sheet surface 61 or the entire surface of the stopper surface 63. Thus, the closed state of the through hole 67 is maintained.

  A through hole 68 is formed in the bottom portion 71 at an intermediate position in the radial direction of the tapered portion 66 and penetrates along the axial direction of the case member 56. A plurality of through holes 68 are formed at intervals in the circumferential direction of the bottom 71 (only one location is shown in FIG. 3 because of a partial cross section). The through hole 68 is arranged between the valve seat part 74 and the inner cylindrical part 72 in the radial direction of the bottom part 71. The through hole 68 is provided inside the through hole 67 in the radial direction of the case member 56, that is, in the radial direction of the bottom portion 71.

  The through-hole 70 at the center of the inner cylindrical portion 72 has a small-diameter hole portion 75 for fitting the mounting shaft portion 28 of the piston rod 21 on the valve seat portion 74 side in the axial direction. A large-diameter hole 76 having a larger diameter than the small-diameter hole 75 is formed on the side opposite to the portion 74. The inside of the large diameter hole 76 is always in communication with the inside of the passage groove 30 of the mounting shaft 28. Therefore, also in the large-diameter hole 76, the large-diameter hole 46 of the piston body 35, the passage groove 30 of the mounting shaft 28, and the large-diameter hole 376 of the case member 356 form an intermediate chamber 85. A part of the mounting shaft portion 28 of the piston rod 21 inserted into the through hole 70 is disposed in the case member 56 in the axial direction.

  The pilot valve 52 includes a metal disk 95 and a rubber seal member 96 fixed to the disk 95. The disc 95 has a circular flat plate shape with a certain thickness, into which the mounting shaft portion 28 of the piston rod 21 can be fitted, and has an outer diameter substantially equal to the outer diameter of the valve seat portion 374 of the case member 356. It has become. The seal member 96 is fixed to the outer peripheral side of the disk 95 opposite to the case member 356 in the axial direction, and has an annular shape. In other words, the pilot valve 52 has an annular seal member 96 on the outer periphery.

  The seal member 96 is slidably and liquid-tightly fitted to the inner peripheral surface of the outer cylindrical portion 73 of the case member 56 over the entire circumference, and always keeps the gap between the pilot valve 52 and the outer cylindrical portion 73 constant. Seal. In other words, the pilot valve 52 has the seal member 96 slidably and closely fitted to the outer cylindrical portion 73 of the case member 56.

  With the partition disc 69 closing the passage 103 in the through hole 67, the space between the pilot valve 52, the case member 56, and the partition disc 69 is a pilot chamber 101 (second pilot chamber) serving as a back pressure chamber of the pilot valve 52. Room). In other words, the pilot chamber 101 includes the case member 56, the partition disk 69, and the pilot valve 52. In this state, the space between the concave portion 64 of the bottom 71 of the case member 56 and the partition disk 69 becomes a variable chamber 102 (housing inner chamber) communicating with the lower chamber 20. In other words, the partition disk 69 forms the variable chamber 102 between the partition disk 69 and the bottom 71 of the case member 56. Therefore, the two pilot chambers 101 and the variable chamber 102 are provided in the case member 56 by being defined by the partition disk 69.

  The variable chamber 102 is in communication with the passage 103 and is always in communication with the lower chamber 20 via the passage 103. The pilot chamber 101, the variable chamber 102, and the partition disk 69 for partitioning the pilot chamber 101 and the variable chamber 102 constitute a frequency sensitive unit 104 that varies the damping force in response to the frequency of reciprocation of the piston 18 (hereinafter, referred to as a piston frequency). I have.

  The partitioned disk 69 has a state in which both the inner and outer peripheral sides abut the sheet surface 61 of the disk abutting portion 62 by surface contact over the entire circumference, and a state in which the inner and outer peripheral sides are both in contact with the sheet surface 61 over the entire circumference. The flow of the oil liquid between the pilot chamber 101 and the variable chamber 102 is interrupted in a state in which the oil is in contact with both side borders with the surface 63 and a state in which the oil is in contact with the stopper surface 63 over the entire circumference. When the partition disk 69 is separated from the bottom 71, the flow of the oil liquid between the pilot chamber 101 and the variable chamber 102 is allowed. The spring disk 54 urges the partition disk 69 so as to contact the seat surface 61. Therefore, the spring disk 54, the partition disk 69, the disk contact portion 62 of the case member 56, and the concave portion 64 Check that the flow of the oil liquid from the pilot chamber 101 side to the variable chamber 102 side, that is, the lower chamber 20 side is restricted, while the oil liquid flow from the variable chamber 102 side, that is, the lower chamber 20 side to the pilot chamber 101 side is permitted. The valve 105 is constituted.

  The partition disk 69, which is the valve body of the check valve 105, is not entirely clamped in the axial direction and is not fixed to any part. The partition disk 69 contacts the spring disk 54 and contacts and separates from the bottom 71 of the case member 56. The partition disk 69 is a floating-type free valve that is entirely movable in the axial direction. The partition disk 69 is moved toward and away from the seat surface 61 by the urging other than the hydraulic pressure applied only by the spring disk 54. Each of the partition disk 69 and the spring disk 54 of the check valve 105 is made of only metal and does not use a rubber seal. The partition disk 69 and the spring disk 54 are both integrally formed by press working.

  The biasing force of the spring disk 54 is set so that the partition disk 69 always shuts off the flow of the oil liquid between the pilot chamber 101 and the variable chamber 102 regardless of the pressure state of the pilot chamber 101 and the variable chamber 102. May be. That is, the partition disk 69 may block the flow of the working fluid in at least one direction, including the flow between the pilot chamber 101 and the variable chamber 102 in both directions.

  Since the concave portion 64 is formed in the bottom portion 71, the partition disk 69 can be bent by the working fluid in the case member 56, and when the pressure in the pilot chamber 101 becomes higher than the pressure in the variable chamber 102, While blocking the communication with the variable chamber 102, it deforms so as to be bent into the recess 64 as described above to expand the capacity of the pilot chamber 101 and decrease the capacity of the variable chamber 102. Also, from this state, when the pressure difference between the pressure in the pilot chamber 101 and the pressure in the variable chamber 102 becomes smaller, the partition disk 69 cuts off the communication between the pilot chamber 101 and the The deformation is made such that the volume of the variable chamber 102 is increased by reducing the entry and the volume of the pilot chamber 101 is reduced. When the pressure in the variable chamber 102 is higher than the pressure in the pilot chamber 101 by the amount of the urging force of the spring disk 54, the partition disk 69 moves away from the seat surface 61 against the urging force of the spring disk 54. The variable chamber 102 and the pilot chamber 101 communicate with each other.

  The plurality of disks 53 have the same outer diameter and an outer diameter smaller than the minimum inner diameter of the seal member 96 of the pilot valve 52. Further, the plurality of disks 53 have an outer diameter smaller than the outer diameter of the inner cylindrical portion 72 of the case member 56 and larger than the inner diameter of the large-diameter hole 76.

  The spring disk 54 has a flat plate-shaped substrate portion 111 having an outer diameter larger than the outer diameter of the disk 53 and smaller than the minimum inner diameter of the seal member 96 of the pilot valve 52, and a pressing plate extending from the substrate portion 111. And a part 112. The substrate portion 111 has an annular shape, and the pressing plate portion 112 extends from the outer peripheral edge of the substrate portion 111 while being inclined to one axial side and radially outward. A plurality of the pressing plate portions 112 are formed at intervals in the circumferential direction of the substrate portion 111 (only one portion is shown in FIG. 3 because of the cross section in FIG. 3), and extends toward the partition disk 69 side. In the spring disk 54, the plurality of pressing plate portions 112 abut against the surface of the partition disk 69 on the pilot valve 52 side to urge the partition disk 69 toward the seat surface 61 to abut on the seat surface 61.

  The disk 55 has an outer diameter smaller than the outer diameter of the substrate portion 111 of the spring disk 54 and larger than the outer diameter of the inner cylindrical portion 72 of the case member 56. The disk 55 is formed with a notch 115 extending radially outward from an inner peripheral edge portion fitted to the mounting shaft portion 28 of the piston rod 21. The passage 116 in the notch 115 is always in communication with the pilot chamber 101 on the one hand, and is always in communication with the intermediate chamber 85 on the other hand. Therefore, the pilot chamber 101 is always in communication with the intermediate chamber 85 via the passage 116 in the notch 115. The passage portion 116 of the disk 55 is a throttle provided between the pilot chamber 101 and the intermediate chamber 85, that is, an orifice.

  The disk 51 can be seated on the valve seat portion 47 of the piston 18 as described above. The disk 51 and the pilot valve 352 constitute the main valve 121 (first main valve). The main valve 121 is provided in a passage portion 38 in a passage hole 37 formed in the piston 18, and is caused by sliding of the piston 18 toward the extension side (upper side in FIG. 3). The damping force is generated by suppressing the flow of the oil liquid from the upstream chamber to the lower chamber 20 (downstream chamber) on the other downstream side.

  The main valve 121 constitutes the damping force generating mechanism 41 (first damping force generating mechanism) together with the valve seat portion 47 of the piston 18. When the disc 51 is separated from the valve seat portion 47 and opened, the main valve 121 allows the oil liquid from the passage portion 38 to radially spread between the piston 18 and the outer cylindrical portion 373 of the case member 356. It flows into the lower chamber 20 via the section 125. The passage portion 38 formed inside each of the plurality of passage holes 37, the passage portion 125 between the main valve 121 and the valve seat portion 47, and the passage portion 125 between the piston 18 and the case member 356 form the passage 130 (the 1 passage). The passage 130 moves the piston 18 to the upper chamber 19 side, that is, the oil liquid as the working fluid flows from the upper chamber 19 which is the upstream chamber in the cylinder 2 to the lower chamber 20 which is the downstream chamber in the extension stroke. It becomes a passage on the extension side. The extension-side damping force generating mechanism 41 composed of the valve seat portion 47 and the main valve 121 is provided in the passage 130, and the main valve 121 opens and closes the passage 130 to suppress the flow of the oil liquid. Generates damping force. The damping force generating mechanism 41 is disposed on the lower chamber 20 side, which is one end side of the piston 18 in the axial direction, and is attached to the piston rod 21.

  The pilot chamber 401 between the pilot valve 352, the case member 356, and the pilot valve 52 applies an internal pressure to the main valve 121 in the direction of the piston 18, that is, in the valve closing direction in which the disc 51 is seated on the valve seat portion 47. The opening of the main valve 121 is adjusted by the pressure of the pilot chamber 401. That is, the damping force generating mechanism 41 including the main valve 121 is a pressure control type damping force generating mechanism in which the opening is adjusted by the pressure in the pilot chamber 401.

  The passage 82 of the disc 50, the intermediate chamber 85, and the passage 416 of the disc 355 allow the passage 38 of the piston 18 and the pilot chamber 401 to always communicate with each other and introduce the oil liquid from the passage 38 into the pilot chamber 401. I do.

  The case member 356, the main valve 121, the disk 353, the disk 355, and the pilot valve 52 have a pilot chamber 401 that communicates with the upper chamber 19 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 416. Thus, a valve opening control mechanism 427 for applying a back pressure to the main valve 121 to control the valve opening is configured.

  Pilot valve 52 seats disc 95 on valve seat portion 374 of case member 356. The pilot valve 52 constitutes a damping force generating mechanism 441 (second damping force generating mechanism) together with the valve seat portion 374 of the case member 356. The pilot valve 52 opens and closes the pilot chamber 401 by generating a damping force by detaching from and seating on the valve seat portion 374. The piston 18 moves to the upper chamber 19 side, that is, from the upper chamber 19 which is the upstream chamber in the cylinder 2 during the extension stroke, to the pilot chamber 401 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 416. When the oil flows, the pilot valve 52 moves the disk 95 away from the valve seat portion 374 and opens the oil liquid from the pilot chamber 401 between the case member 356 and the case member 56. It flows into the lower chamber 20 which is the downstream chamber via the passage part 425 spreading in the direction. At this time, the damping force generating mechanism 441 generates a damping force by the pilot valve 52 suppressing the flow of the oil liquid. The damping force generating mechanism 441 is arranged on the side of the damping force generating mechanism 41 opposite to the piston 18 and is attached to the piston rod 21.

  The pilot chamber 101 between the pilot valve 52, the case member 56, and the partition disk 69 is provided via the passage 38 of the piston 18, the passage 82 of the disk 50, the intermediate chamber 85, and the passage 116 of the disk 55. And communicates with the upper chamber 19. The pilot chamber 101 applies an internal pressure to the pilot valve 52 in the direction of the case member 356, that is, in the valve closing direction in which the disc 95 is seated on the valve seat portion 374. The damping force generating mechanism 441 includes the pilot chamber 101. The damping force generation mechanism 441 is a pressure control type damping force generation mechanism in which the pilot valve 52 is controlled to open by the pressure of the pilot chamber 101. That is, the opening of the damping force generating mechanism 441 including the pilot valve 52 is adjusted by the pressure of the pilot chamber 101.

  The case member 56, the pilot valve 52, the plurality of disks 53, the spring disk 54, the disk 55, and the partition disk 69 constitute a control mechanism 128. The control mechanism 128 has a pilot chamber 101 which is always in communication with the upper chamber 19 via the passage 38, the passage 82, the intermediate chamber 85 and the passage 116, and applies a back pressure to the pilot valve 52. A valve opening control mechanism 127 for controlling valve opening is included. Further, the control mechanism 128 includes a frequency responsive unit 104 that varies the damping force in response to the piston frequency, and controls the flow of the oil liquid from the pilot chamber 101 to the variable chamber 102, that is, the lower chamber 20. A check valve 105 for restricting the flow of the oil liquid from the variable chamber 102 side, that is, the lower chamber 20 side to the pilot chamber 101 side is included.

  The plurality of disks 57 have the same outer diameter, and have an outer diameter slightly larger than the outer diameter of the valve seat portion 74. The plurality of disks 57 constitute a disk valve 131 that can be separated from and seated on the valve seat portion 74. When the disc valve 131 is separated from the valve seat portion 74, the pilot valve 101 and the lower chamber 20 communicate with each other through the passage 135 in the through hole 68, and the flow of the oil liquid therebetween is suppressed. To generate damping force. A through hole 68 is provided at the bottom 71 of the case member 56 so as to face the disk valve 131. The passage portion 135 is provided in parallel with the passage portion 103 in the through hole 67 so that the pilot chamber 101 and the lower chamber 20 can communicate with each other.

  The disk 58 has an outer diameter smaller than that of the valve seat portion 74, and the disk 59 has an outer diameter equal to that of the valve seat portion 74. The annular member 60 has an outer diameter larger than that of the disc valve 131 and has higher rigidity than that of the disc valve 131. The disk 59 and the annular member 60 are in contact with the disk valve 131 when the disk valve 131 is deformed in the opening direction, thereby restricting the deformation of the disk valve 131 in the opening direction beyond the specified value.

  The passage portion 38 of the piston 18, the passage portion 82 of the disc 50, the intermediate chamber 85, the passage portion 116 of the disc 55, the pilot chamber 101, the passage portion 135 of the case member 56, the disc valve 131 and the valve seat portion 74, the variable chamber 102, and the passage 103 of the case member 56 constitute a passage 140 (second passage). Therefore, at least a part of the passage 140 is formed inside the case member 56 which is a housing having the pilot chamber 101 inside. The passage 140 connects the upper chamber 19 and the lower chamber 20 with a route that is partially different from the passage 130.

  In the passage 140, the passage portion 38 on the upper chamber 19 side is common to the passage 130, and the lower chamber 20 side of the passage portion 38 is provided in parallel with the passage 130. That is, the parallel passage 141 including the passage portion 82, the intermediate chamber 85, the passage portion 116, the pilot chamber 101, the passage portion 103, and the passage portion 135 of the passage 140 and the passage portion 125 of the passage 130 are arranged in parallel. Further, the passage portion 82, the intermediate chamber 85, the passage portion 416, the pilot chamber 401 and the passage portion 425 are arranged in parallel with the passage portion 125 of the passage 130. The passage 82, the intermediate chamber 85, and the passage 116 allow the passage 130 to communicate with the pilot chamber 101. The passage 82, the intermediate chamber 85, and the passage 416 allow the passage 130 to communicate with the pilot chamber 401.

  The check valve 105 including the spring disk 54, the partition disk 69, and the bottom 71 of the case member 56 is provided in the parallel passage 141 of the passage 140, and is used to move oil from the pilot chamber 101 to the lower chamber 20 during the extension stroke. While restricting the flow of the oil liquid from the lower chamber 20 to the pilot chamber 101 in the contraction process. The oil liquid introduced into the pilot chamber 101 by opening the check valve 105 from the lower chamber 20 flows into the upper chamber 19 via the passage 140 including the pilot chamber 101.

  The disc valve 131 is separated from the valve seat 74 when the pressure in the pilot chamber 101 reaches a predetermined pressure. The disk valve 131, together with the valve seat portion 74, constitutes a damping force generation mechanism 145 that is a hard valve that opens when the pressure in the pilot chamber 101 reaches a predetermined pressure to generate a damping force. The damping force generation mechanism 145 is provided in the parallel passage 141 of the passage 140 that is parallel to the passage 130, and is provided in the passage 135 that connects the pilot chamber 101 and the lower chamber 20. The damping force generating mechanism 145 is provided outside the case member 56, and the disk valve 131 is arranged to face the bottom 71 of the case member 56. A through hole 68 is provided in the bottom 71 of the case member 56 so as to face the disk valve 131 of the damping force generating mechanism 145.

  As shown in FIG. 2, the contraction-side damping force generating mechanism 42 includes, in order from the piston 18 side in the axial direction, one disc 161, one disc 162, a plurality of discs 163, and a plurality of discs. It has a disk 164, one disk 165, one disk 166, and one annular member 167. Each of the disks 161 to 166 and the annular member 167 is made of metal, and has a circular plate shape with a certain thickness inside, into which the mounting shaft portion 28 of the piston rod 21 can be fitted.

  The disk 161 has an outer diameter smaller than the inner diameter of the valve seat portion 48 of the piston 18. The disk 162 has an outer diameter substantially equal to the outer diameter of the valve seat portion 48 of the piston 18 and can be seated on the valve seat portion 48. A notch 171 is formed on the outer peripheral side of the disk 162, and the notch 171 traverses the valve seat portion 48 in the radial direction.

  The plurality of disks 163 have the same outer diameter, and have the same outer diameter as the outer diameter of the disk 162. The plurality of disks 164 have the same outer diameter, and have an outer diameter smaller than the outer diameter of the disk 163. The disk 165 has an outer diameter smaller than the outer diameter of the disk 164. The disk 166 has an outer diameter larger than the outer diameter of the disk 164 and smaller than the outer diameter of the disk 163. The annular member 167 has an outer diameter smaller than the outer diameter of the disk 166, and is thicker and more rigid than the disks 161 to 166. This annular member 167 is in contact with the shaft step 29 of the piston rod 21.

  The disks 162 to 164 constitute a disk valve 172 that can be separated from and seated on the valve seat portion 48. When the disc valve 172 is separated from the valve seat portion 48, the passage portion 40 in the passage hole 39 communicates with the upper chamber 19 and the flow of the oil liquid therebetween is suppressed to generate a damping force. The inside of the notch 171 of the disk 162 is a fixed orifice 173 that allows the upper chamber 19 and the lower chamber 20 to communicate even when the disk 162 is in contact with the valve seat portion 48. The disk 166 and the annular member 167 restrict the deformation of the disk valve 172 in the opening direction beyond the specified value.

  In the present embodiment, both the expansion-side disk valve 131 and the contraction-side disk valve 172 have been described as examples of disk valves with inner clamps. However, the present invention is not limited to this, and any mechanism that generates a damping force may be used. For example, it may be a lift-type valve that urges the disc valve with a coil spring, or may be a poppet valve.

  As described above, the control mechanism unit 128 including the case member 56, the pilot valve 52, the plurality of disks 53, the spring disks 54, the disks 55, and the partition disks 69 includes the valve opening control mechanism 127, the frequency sensitive unit 104, and the check valve. 105. As shown in FIG. 3, the frequency sensitive unit 104 has its partition disk 69 deformable in the recess 64, and changes the capacity of the pilot chamber 101 by deforming in the recess 64. The partition disk 69 is deformed in accordance with the frequency of the reciprocating motion of the piston 18, and changes the capacity of the pilot chamber 101 constantly communicating with the upper chamber 19 and the capacity of the variable chamber 102 constantly communicating with the lower chamber 20.

  As shown in FIG. 2, an attachment shaft portion 28 is inserted through the piston rod 21, and an annular member 167, a disk 166, a disk 165, a plurality of disks 164, a plurality of Disk 163, disk 162, disk 161, piston 18, disk 50, disk 51, pilot valve 352, disk 353, disk 355, case member 356, pilot valve 52, a plurality of disks 53, spring disk 54, disk 55, The case member 56, the plurality of disks 57, the disks 58, the disks 59, and the annular member 60 are stacked in this order. At that time, as shown in FIG. 3, a partition disk 69 is arranged between the bottom 71 of the case member 56 and the spring disk 54. At this time, the case member 356 fits the seal member 396 of the pilot valve 352 to the outer cylindrical portion 373, and the case member 56 fits the seal member 96 of the pilot valve 52 to the outer cylindrical portion 73. .

  As shown in FIG. 2, in a state where the components are arranged as described above, the nut 185 is screwed into the male screw 31 of the mounting shaft 28 projecting from the annular member 60. As a result, the components from the annular member 167 to the annular member 60 stacked as described above are clamped in the axial direction while the inner peripheral side or the entirety is sandwiched between the axial step portion 29 of the piston rod 21 and the nut 185. ing. At this time, the partition disk 69 is not clamped in the axial direction, but is clamped between the spring disk 54 and the case member 56.

  As shown in FIG. 1, the above-described base valve 25 is provided between the bottom member 12 of the outer cylinder 4 and the inner cylinder 3. The base valve 25 includes a base valve member 191 that separates the lower chamber 20 and the reservoir chamber 6, a disk 192 provided below the base valve member 191, that is, on the reservoir chamber 6 side, and an upper side, that is, a lower side of the base valve member 191. It has a disk 193 provided on the chamber 20 side and a mounting pin 194 for mounting the disk 192 and the disk 193 on the base valve member 191.

  The base valve member 191 has an annular shape, and a mounting pin 194 is inserted through the center in the radial direction. The base valve member 191 has a plurality of passage holes 195 through which the oil liquid flows between the lower chamber 20 and the reservoir chamber 6, and the lower chamber is provided outside the passage holes 195 in the radial direction of the base valve member 191. A plurality of passage holes 196 for allowing the oil liquid to flow between the reservoir 20 and the reservoir chamber 6 are formed. The disc 192 on the reservoir chamber 6 side allows the flow of the oil liquid from the lower chamber 20 to the reservoir chamber 6 through the passage hole 195, while the flow of the oil liquid from the reservoir chamber 6 to the lower chamber 20 through the passage hole 195. Suppress. The disc 193 allows the flow of the oil liquid from the reservoir chamber 6 to the lower chamber 20 through the passage hole 196, while suppressing the flow of the oil liquid from the lower chamber 20 to the reservoir chamber 6 through the passage hole 196.

  The disk 192 and the base valve member 191 constitute a contraction-side damping valve mechanism 197 that opens during the contraction stroke of the shock absorber 1 to flow the oil liquid from the lower chamber 20 to the reservoir chamber 6 and generate a damping force. ing. The disc 193 and the base valve member 191 constitute a suction valve mechanism 198 that opens during the extension stroke of the shock absorber 1 to flow the oil liquid from the reservoir chamber 6 into the lower chamber 20. The suction valve mechanism 198 supplies the oil liquid from the reservoir chamber 6 to the lower chamber 20 without substantially generating a damping force so as to compensate for the shortage of the liquid mainly caused by the piston rod 21 extending from the cylinder 2. Performs the function of flowing.

  The hydraulic circuit diagram of the shock absorber 1 according to the first embodiment is as shown in FIG. That is, the upper chamber 19 communicates with the intermediate chamber 85 via the passage 82, the pilot chamber 401 communicates with the intermediate chamber 85 via the passage 416, and the pilot chamber 101 and the intermediate chamber 85 communicate with the passage 116. Is communicated through. The upper chamber 19 and the lower chamber 20 can communicate with each other via a damping force generation mechanism 41 and a damping force generation mechanism 42. Further, the pilot chamber 401 can communicate with the lower chamber 20 via the damping force generating mechanism 441, and the pilot chamber 101 can communicate with the lower chamber 20 via the damping force generating mechanism 145. The opening of the damping force generating mechanism 41 is controlled by the pressure of the pilot chamber 401, and the opening of the damping force generating mechanism 441 is controlled by the pressure of the pilot chamber 101. The pilot chamber 101 can communicate with the variable chamber 102 via a check valve 105, and the variable chamber 102 communicates with the lower chamber 20. Here, the passage portion 82, the passage portion 416, and the passage portion 116, which are all orifices communicating with the intermediate chamber 85, have a passage area larger than that of the passage portion 116 and larger than that of the passage portion. The passage portion 416 is also larger.

  In the shock absorber 1 of the first embodiment, during the extension stroke in which the piston rod 21 moves to the extension side, the pressure in the upper chamber 19 shown in FIG. The oil liquid flows toward the lower chamber 20 through the passage portion 38 of FIG. In the flow of the oil liquid from the upper chamber 19 through the passage 38 during the extension stroke, the damping including the valve seat portion 47, the main valve 121, and the fixed orifice 92 of the piston 18 from the passage 38 shown in FIG. There is a flow path passing through the force generating mechanism 41 and flowing to the lower chamber 20 through the passage portion 125 between the piston 18 and the case member 356. This flow is a flow passing through the passage 130.

  In addition, the flow of the oil liquid from the upper chamber 19 through the passage section 38 in the extension stroke flows in parallel with the above from the passage section 38 through the passage section 82 of the disk 50, passes through the intermediate chamber 85, The gas flows through the passage 416 of the disk 355 to the pilot chamber 401, which is the back pressure chamber of the main valve 121, and passes from the pilot chamber 401 through the valve seat 374 of the case member 356 and the damping force generating mechanism 441 including the pilot valve 52. There is a flow path that flows to the lower chamber 20 through a passage 425 between the case members 356 and 56. Here, the pressure in the intermediate chamber 85 and the pilot chamber 401 is the same because the passage 416 serving as a throttle between them is sufficiently wide.

  Further, the flow of the oil liquid from the upper chamber 19 through the passage 38 in the extension stroke flows in parallel with the above from the passage 38 through the passage 82 in the disk 50 and through the intermediate chamber 85. Flows through the passage portion 116 of the disc 55 to the pilot chamber 101 which is a back pressure chamber of the pilot valve 52, from the pilot chamber 101, from the passage portion 135 of the case member 56, to the valve seat portion 74 of the case member 56 and the disc valve There is a flow path that flows to the lower chamber 20 through the damping force generating mechanism 145 including 131. This flow is a flow through the passage 140.

  At the time of low frequency input (large amplitude input) to the shock absorber 1, the amount of oil flowing from the upper chamber 19 to the pilot chamber 101 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 116 is reduced. Accordingly, the amount of deflection of the partition disk 69 of the frequency sensitive section 104 also increases, and the partition disk 69 is brought into surface contact with the stopper surface 63 of the recess 64 on the side of the case member 56 and deformed until bending is restricted. When the deflection of the partition disk 69 is regulated by the stopper surface 63 in this manner, the volume of the pilot chamber 101 cannot be increased, and thereafter the pressure in the pilot chamber 101 increases to a high pressure, and the damping force generating mechanism 441 The valve opening pressure of the pilot valve 52 increases. Until the pilot valve 52 opens, the pressure in the pilot chamber 401 also increases, so the valve opening pressure of the main valve 121 of the damping force generating mechanism 41 also increases. Therefore, as shown by the solid line X1 in FIG. 5, the damping force has hard characteristics.

  At the time of this low-frequency input, in a very low speed range where the piston speed which is the speed of the piston 18 and the piston rod 21 is very low, the oil liquid entering the passage 38 from the upper chamber 19 closes the damping force generation mechanism 41. It flows through the fixed orifice 92 of the main valve 121 in the valve state, and flows into the lower chamber 20 only through the passage 125 between the piston 18 and the case member 356. Therefore, the characteristic of the damping force with respect to the piston speed becomes an orifice characteristic, and the rate of increase of the damping force becomes relatively high with the rise of the piston speed (see piston speeds 0 to v1 in FIG. 5).

  In this state, when the piston speed is increased to increase the flow rate of the piston 18 through the passage 38, the oil flowing from the upper chamber 19 into the passage 38 opens the damping force generating mechanism 145, which is a hard valve. Then, it flows into the lower chamber 20. Thereafter, at a predetermined piston speed v1 indicated by a solid line X1 shown in FIG. 5, the oil liquid from the upper chamber 19 flows to the pilot chamber 401 through the passage 38, the passage 82, the intermediate chamber 85, and the passage 416, and The pilot valve 52 of the damping force generating mechanism 441 is opened from the chamber 401, and flows into the lower chamber 20 via the passage 425 between the case members 356 and 56. Therefore, the characteristic of the damping force with respect to the piston speed becomes a valve characteristic, and the rate of increase of the damping force is relatively low with respect to the increase of the piston speed (see piston speeds v1 to v2 in FIG. 5).

  When the piston speed is further increased, at a predetermined piston speed v2 indicated by a solid line X1 shown in FIG. 5, the oil liquid flowing into the passage portion 38 from the upper chamber 19 flows into the flow of the damping force generating mechanism 441 that opens as described above. In addition, the damping force generation mechanism 41 is opened to flow into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. Therefore, the rate of increase of the damping force is further reduced with respect to the increase of the piston speed (see the piston speed v2 and thereafter in FIG. 5).

  At the time of high frequency input (small amplitude input) to the shock absorber 1, the amount of oil flowing from the upper chamber 19 to the pilot chamber 101 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 116 is small. The bending amount of the partition disk 69 of the sensitive portion 104 is also reduced, and the partition disk 69 is deformed within a range where the partition disk 69 does not contact the stopper surface 63 of the concave portion 64 on the case member 56 side. Therefore, since the inflow of the oil liquid into the pilot chamber 101 can be absorbed by the bending of the partition disk 69, the pressure in the pilot chamber 101 does not increase but becomes low, so that the valve opening pressure of the pilot valve 52 of the damping force generation mechanism 441 is reduced. Is low. In addition, since the pilot valve 52 is opened from a low pressure in this manner, the pressure in the pilot chamber 401 does not increase and becomes a low pressure, so that the valve opening pressure of the main valve 121 of the damping force generating mechanism 41 is also low. Therefore, as shown by the solid line X2 in FIG. 5, the damping force has a soft characteristic compared with the low frequency input shown by the solid line X1.

  Also at the time of this high-frequency input, as in the case of the low-frequency input, in a very low speed range in which the piston speed is very low, the oil liquid entering the passage portion 38 from the upper chamber 19 is in a closed state of the damping force generation mechanism 41. It flows only through the fixed orifice 92 of the main valve 121 and flows into the lower chamber 20 only through the passage 125 between the piston 18 and the case member 356. For this reason, the characteristic of the damping force with respect to the piston speed becomes an orifice characteristic, and the rate of increase of the damping force relatively increases with the rise of the piston speed (see piston speeds 0 to v3 in FIG. 5).

  In this state, when the piston speed is increased to increase the flow rate of the piston 18 through the passage 38, at a predetermined piston speed v3 indicated by a solid line X2 shown in FIG. , Through the passage portion 82, the intermediate chamber 85, and the passage portion 416, to the pilot chamber 401, and from the pilot chamber 401, the pilot valve 52 of the damping force generating mechanism 441 is opened. Flows into the lower chamber 20 through the passage portion 425. Therefore, the characteristic of the damping force with respect to the piston speed becomes a valve characteristic, and the rate of increase of the damping force is relatively low with respect to the increase of the piston speed (see piston speeds v3 to v4 in FIG. 5).

  When the piston speed is further increased, at a predetermined piston speed v4 indicated by a solid line X2 shown in FIG. 5, the oil liquid flowing from the upper chamber 19 into the passage portion 38 flows into the flow of the damping force generating mechanism 441 that opens as described above. In addition, the main valve 121 of the damping force generating mechanism 41 is opened to flow into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. Therefore, the rate of increase of the damping force is further reduced with respect to the increase of the piston speed (see the piston speed v4 and thereafter in FIG. 5).

  According to the above-described shock absorber 1, at the time of low-frequency input with hard damping force characteristics, the number of valve opening points increases as shown by the solid line X1 in FIG. 5, and the conventional valve opening shown by the broken line X3 in FIG. As compared with a shock absorber having a small number of valve points, it is possible to reduce a sudden change in the valve opening characteristic at the time of valve opening. Even at the time of high-frequency input with a soft damping force characteristic, the number of valve opening points increases as shown by a solid line X2 in FIG. 5, and compared with the conventional buffer having a small valve opening point shown by a broken line X4 in FIG. It is possible to alleviate the transient sudden change in the valve opening characteristic when the valve is opened. Here, since the transient change in force at the time of opening the valve is transmitted to the vehicle body, which causes the riding comfort and abnormal noise heard inside the vehicle, the shock absorber 1 according to the first embodiment improves the riding comfort. The occurrence of abnormal noise can be prevented.

  Even if the two-stage pressure control is performed by the two damping force generating mechanisms 441 and 41, there is no qualitative change in the frequency characteristics. At the time of low frequency input, a hard damping force characteristic is obtained, and at the time of high frequency input, two-stage switching of soft damping force characteristic is performed. The cutoff frequency depends on the total pressure loss at two locations in series of the passage portion 116 and the passage portion 82, and thus depends on the flow passage area of the passage portions 116 and 82. Therefore, the cutoff frequency can be easily tuned by adjusting the flow passage areas of the passage portions 116 and 82.

  In the contraction stroke in which the piston rod 21 moves to the contraction side, when the piston speed is low, the oil liquid from the lower chamber 20 passes through the passage portion 40 in the passage hole 39 on the contraction side shown in FIG. Flows through the fixed orifice 173 of the disk valve 172 to the upper chamber 19 to generate a damping force having orifice characteristics. Therefore, the characteristic of the damping force with respect to the piston speed is such that the rate of increase of the damping force is relatively high with respect to the increase of the piston speed (see piston speeds 0 to v5 in FIG. 5).

  When the piston speed increases, the oil liquid introduced from the lower chamber 20 into the passage portion 40 in the contraction-side passage hole 39 basically opens the disc valve 172 of the damping force generating mechanism 42 while the disc valve 172 is in contact with the oil valve. This flows into the upper chamber 19 through the space between the valve seat 48 and the damping force of the valve characteristics. For this reason, the characteristic of the damping force with respect to the piston speed is such that the rate of increase of the damping force decreases as the piston speed increases (see piston speed v5 and thereafter in FIG. 5).

  Here, in the frequency responsive section 104, during the contraction stroke, the pressure in the lower chamber 20 increases, and the pressure in the variable chamber 102 becomes higher than the pressure in the pilot chamber 101. As a result, the partition disk 69 as the valve body of the check valve 105 is separated from the seat surface 61 of the disk contact portion 62. As a result, the check valve 105 opens the passage 140 and allows the oil liquid to flow from the lower chamber 20 to the upper chamber 19 via the passage 140. At that time, the partitioned disk 69 is separated from the disk abutting portion 62 to eliminate the differential pressure, and further movement is suppressed.

  Patent Literature 1 described above describes a shock absorber in which a damping force is variable in response to a frequency. By the way, in the shock absorber, for example, if the characteristic change when the damping force characteristic is switched is large, there is a possibility that the ride comfort may be reduced and noise may be generated. For this reason, it is required that the damper has a smooth damping force characteristic.

  On the other hand, the shock absorber 1 of the first embodiment is a main valve that is provided in the passage 130 and suppresses the flow of the oil liquid from the upper chamber 19 to the lower chamber 20 by sliding the piston 18 to generate a damping force. A first damping force generation mechanism 41 having a pressure chamber 121 and a pilot chamber 401 for applying pressure to the main valve 121 in a valve closing direction is provided. In addition, at least a part of a passage 140 parallel to the passage 130 is formed in a bottomed cylindrical case member 56 formed therein, and the bottom member 71 of the case member 56 is provided movably with respect to the case member 56. And a partition disk 69 forming a variable chamber 102 therebetween. By forming the variable chamber 102 by the case member 56 and the partition disk 69, the damping force can be changed in response to the frequency. Then, in addition to the first damping force generation mechanism 41, a pilot valve 52 that generates a damping force by suppressing the flow of the oil liquid from the pilot chamber 401 to the lower chamber 20, and applies pressure to the pilot valve 52 in the valve closing direction. And a second damping force generating mechanism 441 having a pilot chamber 101 to be operated. Thereby, the damping force can be switched to a plurality of stages in response to an increase in the piston speed. Therefore, the damping force characteristics can be made smooth. That is, the characteristic change when the damping force characteristic is switched in the shock absorber can be made smooth. As a result, it is possible to suppress a decrease in ride comfort and generation of abnormal noise.

  The pilot chamber 101 of the second damping force generating mechanism 441 is constituted by the pilot valve 52 of the second damping force generating mechanism 441, the case member 56 for varying the damping force in response to the frequency, and the partition disk 69. Therefore, the number of parts can be reduced. That is, since the case member 56 and the pilot chamber 101 can be shared by the valve opening control mechanism 127 and the frequency sensing unit 104, the number of parts can be reduced. Therefore, cost reduction and weight reduction can be achieved.

[Second embodiment]
Next, the second embodiment will be described mainly with reference to FIGS. 6 to 8, focusing on differences from the first embodiment. Parts common to the first embodiment are denoted by the same names and the same reference numerals.

  In the second embodiment, as shown in FIG. 6, a passage groove 490 different from the passage groove 30 is formed between the passage groove 30 of the mounting shaft portion 28 of the piston rod 21 and the male screw 31. The inside of the passage groove 490 is a passage portion 491.

  Further, in the second embodiment, a damping force generating mechanism 41A (second damping force generating mechanism) substantially similar to the damping force generating mechanism 41 is provided instead of the damping force generating mechanism 441 of the first embodiment. . Here, in order to distinguish each component of the damping force generating mechanism 41A from each component of the damping force generating mechanism 41, the description will be given with “A” added to the reference numeral of the corresponding component of the damping force generating mechanism 41.

  The damping force generating mechanism 41A includes a disk 50A that is partially different from the disk 50, a disk 51A that is the same part as the disk 51, a pilot valve 352A that is the same part as the pilot valve 352, and a disk that is the same part as the disk 353. 353A, a disk 355A that is the same component as the disk 355, a case member 356A (case) that is the same component as the case member 356, and the disk 500.

  The disk 51A and the pilot valve 352A constitute a main valve 121A (second main valve). A space between the pilot valve 352A and the case member 356A is a pilot chamber 401A (second pilot chamber) for applying pressure to the main valve 121A in the valve closing direction. The inside of the large-diameter hole 376A of the through hole 370A of the case member 356A forms an intermediate chamber 85. The disc valve 131 is in contact with the valve seat portion 374A of the case member 356A.

  The outer diameter of the disk 50A is smaller than the inner diameter of the valve seat portion 374 of the case member 356. Notch 81 of disk 50 is not formed in disk 50A.

  The disk 51A has an outer diameter substantially equal to the outer diameter of the valve seat portion 374 of the case member 356. The disk 51 </ b> A is in contact with the valve seat 374, and opens and closes the pilot chamber 401 of the case member 356 by separating and contacting the valve seat 374. The notch 91A of the disk 51A crosses the valve seat portion 374 in the radial direction. Therefore, the inside of the notch 91A is a fixed orifice 92A that constantly connects the pilot chamber 401 to the lower chamber 20 via the passage 425.

  A space between the pilot valve 352A, the case member 356A, and the disk valve 131 is a pilot chamber 401A. The pilot chamber 401A is always in communication with the intermediate chamber 85 via a passage 416A in a notch 415A of the disk 355A. The passage 416A in the notch 415A is a throttle provided between the intermediate chamber 85 and the pilot chamber 401A, that is, an orifice.

  As shown in FIG. 7, the disc 500 has an outer diameter smaller than the inner diameter of the valve seat portion 374A, and extends radially outward from an inner peripheral edge fitted to the mounting shaft portion 28 of the piston rod 21. A notch 501 is formed. The passage portion 502 in the notch 501 is always in communication with the passage portion 491 in the passage groove 490 of the piston rod 21.

  As shown in FIG. 6, the main valve 121A including the disk 51A and the pilot valve 352A forms a damping force generating mechanism 41A together with the valve seat portion 374 of the case member 356. When the disk 51A is separated from the valve seat portion 374 and opened, the main valve 121A lowers the oil liquid in the pilot chamber 401 via a passage portion 425 that radially spreads between the case member 356 and the case member 356A. Flow into room 20.

  The pilot chamber 401A between the main valve 121A, the case member 356A, the disk valve 131, and the disk 500 is closed by closing the main valve 121A in the direction of the case member 356, that is, by seating the disk 51A on the valve seat portion 374. Apply internal pressure in the direction. The opening of the main valve 121A is adjusted by the pressure of the pilot chamber 401A. That is, the damping force generation mechanism 41A including the main valve 121A is a pressure control type damping force generation mechanism whose valve opening is adjusted by the pressure of the pilot chamber 401A.

  The disc valve 131 is separated from the valve seat 374A when the pressure in the pilot chamber 401A reaches a predetermined pressure. The disk valve 131, together with the valve seat portion 374A, constitutes a damping force generation mechanism 145 which is a hard valve that opens when the pressure in the pilot chamber 401A reaches a predetermined pressure to generate a damping force. In the disk valve 131, a plurality of disks on the side of the case member 356A can be seated on the valve seat portion 374A, and the diameter of the disk decreases as the distance from the case member 356A increases.

  The mounting shaft 28 of the piston rod 21 has a disk 511 having a diameter smaller than the minimum diameter of the disk valve 131 and a disk 512 having a diameter larger than the disk 511 on the side opposite to the case member 356A of the disk valve 131. A frequency sensing unit 530 that varies the damping force in response to the piston frequency is provided adjacent to the opposite side of the disk 512 from the disk 511.

  As shown in FIG. 7, the frequency sensitive section 530 includes, in order from the disk 512 side in the axial direction, one case member 531 (housing) that contacts the disk 512, and a plurality of (specifically, two) disks 533. And one partition disk 534 (disk), one disk 535, one disk 536, and one lid member 539. The case member 531, the disks 533, 535, 536, and the lid member 539 are made of metal. Each of the disks 533, 535, and 536 has a circular flat plate shape with a constant thickness, into which the mounting shaft portion 28 of the piston rod 21 can be fitted. The case member 531 and the lid member 539 are formed in an annular shape in which the mounting shaft 28 of the piston rod 21 can be fitted inside. The case member 531 and the lid member 539 constitute a box-shaped frequency-sensitive part case 540. The mounting shaft 28 of the piston rod 21 is partially disposed inside the case member 531.

  The case member 531 has a bottomed cylindrical shape having a perforated disk-shaped bottom portion 541 and a cylindrical tube portion 544 projecting from the outer peripheral side of the bottom portion 541 to one side along the axial direction of the bottom portion 541. The bottom portion 541 includes a perforated disk-shaped bottom main portion 547, an annular protruding portion 542 protruding from the inner peripheral side of the bottom main portion 547 toward the cylindrical portion 544 in the axial direction with respect to the bottom main portion 547, An annular support portion 543 is provided between the protrusion 542 of the main body portion 547 and the cylindrical portion 544 to protrude toward the cylindrical portion 544 in the axial direction from the bottom main body portion 547. In other words, the bottom 541 has a protruding portion 542 protruding on the same side as the cylindrical portion 544 than the bottom main portion 547 on the inner peripheral side, and at the radially intermediate position on the same side as the cylindrical portion 544 than the bottom main portion 547. Protruding support portions 543 are respectively formed.

  The projecting portion 542 is partially formed in the circumferential direction with a flow channel 548 crossing the projecting portion 542 in the radial direction. The support portion 543 is partially formed in the circumferential direction with a flow channel groove 503 crossing the support portion 543 in the radial direction. On the inner peripheral side of the bottom portion 541, a small-diameter hole portion 545 for fitting the mounting shaft portion 28 of the piston rod 21 is formed on the side opposite to the axially protruding portion 542, and on the axially protruding portion 542 side. A large-diameter hole 546 having a larger diameter than the small-diameter hole 545 is formed. The flow channel 548 is open to the large-diameter hole 546. An opening 549 is provided on the side of the cylindrical portion 544 opposite to the bottom 541. Therefore, the case member 531 includes a cylindrical portion 544 having an opening 549 at one end, and a bottom portion 541 that expands radially inward from a side opposite to the opening 549 of the cylindrical portion 544. The cylindrical portion 544 has a tapered shape in which the inner diameter increases as the inner peripheral surface 550 approaches the opening 549 from the bottom 541. The lid member 539 is provided on the opening 549 side of the cylindrical portion 544 of the cylindrical case member 531, and forms the frequency sensitive part case 540 with the case member 531.

  The mounting shaft 28 penetrates through the center of the case member 531 in the radial direction in the axial direction, and a plurality of disks 533, partition disks 534, disks 535, and disks 536 form the mounting shaft 28 in the case member 531. It is arranged so as to penetrate inside.

  The bottom 541 of the case member 531 supports the inner peripheral side of the disk 512 at the outer end on the side of the small-diameter hole 545 in the axial direction, and is the inner end on the side of the large-diameter hole 546 in the axial direction. The outer peripheral side of the disk 533 is supported by the protrusion 542. The support portion 543 of the case member 531 supports a radially intermediate position of the annular partition disk 534 at an end on the protruding tip side. The support portion 543 always communicates the radial inside and the radial outside of the support portion 543 in the case member 531 by the flow channel groove 503.

  The plurality of disks 533 have an outer diameter smaller than the outer diameter of the protruding portion 542 of the case member 531. The flow channel 548 traverses the protrusion 542 in the radial direction.

  The partition disk 534 includes a perforated circular flat plate-shaped flexible disk 555 made of a metal material and an elastic seal member 556 made of a rubber material fixed to the outer peripheral side of the disk 555. The partition disk 534 has a circular shape as a whole, and can be elastically deformed, that is, bendable. The annular disk 555 has an inner diameter larger than the outer diameter of the disk 533, and has an inner diameter in which the disk 533 can be arranged with a gap in the radial direction inside. The thickness of the disc 555 is smaller than the thickness of the disc 533 (two discs). The disk 555 has an inner diameter smaller than the outer diameter of the disk 535, and can abut on the disk 535. The disk 555 has an outer diameter larger than the outer diameter of the support portion 543 of the case member 531 and smaller than the inner diameter of the cylindrical portion 544. The disk 555 is disposed in the case member 531 with the mounting shaft 28 penetrating inward. The disk 555 is provided on the bottom 541 in the case member 531. The cylindrical portion 544 of the case member 531 has a tapered shape in which the inner diameter increases as the distance from the bottom portion 541 toward the partition disk 534 increases.

  The seal member 556 is fixed to the outer peripheral side of the disk 555 in an annular shape. The entire surface of the seal member 556 facing the disk 555 is fixed to the disk 555 all around. The seal member 556 includes a seal portion 558 that protrudes from the disk 555 on the side opposite to the axial lid member 539, and a stopper portion 559 that protrudes from the disk 555 toward the axial lid member 539. The seal portion 558 has a cylindrical shape and is slidably and liquid-tightly fitted over the entire inner surface of the cylindrical portion 544 of the case member 531 in a liquid-tight manner. Is always sealed.

  The stopper 559 is formed intermittently in the circumferential direction of the disk 555. The stopper portion 559 abuts against the lid member 539 when the partition disk 534 is deformed toward the lid member 539 and elastically deforms. When the stopper portion 559 is deformed to the maximum, further deformation of the partition disk 534 is suppressed. The seal 558 covers the outer peripheral surface of the disk 555 and is connected to the stopper 559.

  The partition disk 534 is centered with respect to the case member 531 when the seal portion 558 contacts the cylindrical portion 544 of the case member 531 over the entire circumference. In addition, the partition disk 534 is supported by the disk 555 abutting on the support portion 543 of the case member 531.

  The protrusion 542 of the case member 531 and the disk 535 have an outer diameter larger than the inner diameter of the disk 555 of the partition disk 534. Therefore, the partition disk 534 has the inner peripheral side of the disk 555 disposed between the projecting portion 542 of the case member 531 and the disk 535, and is movable within a range therebetween. In a state where there is no pressure difference between the front side and the back side of the partition disk 534, the disk 555 is supported in contact with the support portion 543 and the disk 535. The disk 535 is a seat portion on which the partition disk 534 is seated.

  The partition disk 534 is configured such that the inner peripheral side of the disk 555 can move between the protrusion 542 of the case member 531 and the disk 535 within the axial length of the plurality of disks 533. Further, the partition disk 534 is provided with an annular seal portion 558 for sealing the space between the disk 555 and the case member 531 on the outer peripheral side which is the non-support side opposite to the support by the disk 535. The partition disk 534 has a simple support structure in which the inner peripheral side is not clamped from both sides and only one side is supported by the disk 535. The disk 536 has an outer diameter larger than the outer diameter of the disk 535.

  The lid member 539 has a cylindrical tubular portion 561 and a disk-shaped flange portion 562 that extends radially outward from an axial center position of the outer peripheral portion of the tubular portion 561. The cylindrical portion 561 is thicker on both sides in the axial direction than the flange portion 562. The attachment shaft 28 of the piston rod 21 is fitted to the inside of the cylindrical portion 561 of the lid member 539.

  In the lid member 539, the flange portion 562 is disposed axially outside the cylindrical portion 544 of the case member 531, and the inside of the frequency-sensitive portion case 540 is always communicated with the lower chamber 20 between the flange portion 562 and the cylindrical portion 544. A communication path 565 is formed.

  Here, the lid member 539 has a mirror-symmetric shape with respect to a plane passing through the central position in the axial direction and orthogonal to the axial direction. In other words, the lid member 539 has no distinction between the front and back sides, and has a shape that does not cause erroneous assembly due to wrong front and back sides. The lid member 539 can be formed by sintering.

  In the partition disk 534, the seal portion 558 contacts the inner peripheral surface 550 of the cylindrical portion 544 of the case member 531 over the entire circumference, and seals the gap between the partition disk 534 and the cylindrical portion 544. That is, the partition disk 534 is a packing valve. The seal portion 558 always seals the gap between the partition disk 534 and the cylindrical portion 544 even if the partition disk 534 is displaced and deformed within a range permitted in the frequency sensitive case 540. The partition disk 534 is centered by being fitted into the frequency sensitive part case 540, and in this state, the disk 555 makes the inner peripheral portion contact the disk 535 over the entire circumference, thereby forming a gap with the disk 535. Seal.

  The partition disk 534 partitions the inside of the frequency-sensitive part case 540 into two chambers: a variable-capacity case chamber 571 (inside housing) on the bottom 541 side and a variable-capacity case chamber 572 on the lid member 539 side. In other words, the two case chambers 571 and 572 are provided in the case member 531 of the frequency-sensitive part case 540, being defined by the partition disk 534. The case chamber 571 is formed between the partition disk 534 and the bottom 541 of the case member 531.

  In the second embodiment, the passage 82 of the disc 50, the intermediate chamber 85, the passage 416A of the disc 355A, the pilot chamber 401A, the passage 502 of the disc 500, and the passage in the passage groove 490 of the piston rod 21 shown in FIG. The portion 491, the passage portion 582 in the large-diameter hole portion 546 of the case member 531, the passage portion 581 in the flow groove 548 of the case member 531, the case chamber 571, and the case chamber 572 constitute the parallel passage 141 of the passage 140. ing. Therefore, at least a part of the passage 140 connecting the upper chamber 19 and the lower chamber 20 is formed inside the case member 531 which is a housing having the case chambers 571 and 572 therein, with a different route from the passage 130. I have.

  The intermediate chamber 85 is always in communication with the pilot chamber 401A via the passage 416A of the disk 355A, and the passage 416A is a throttle provided between the intermediate chamber 85 and the pilot chamber 401A, that is, an orifice. . The pilot chamber 401A is always in communication with the case chamber 571 via the passage 502 of the disk 500, the passage 491 of the piston rod 21, the passage 582 of the case member 531 and the passage 581. The passage portion 502 of the disk 500 is a throttle provided between the pilot chamber 401A and the case chamber 571, that is, an orifice. The case chamber 572 is always in communication with the lower chamber 20 via a communication path 565 between the case member 531 and the lid member 539.

  The frequency-sensitive part 530 has the frequency-sensitive part case 540 provided in the parallel passage 141 of the passage 140. Therefore, two case chambers 571 and 572 which are a part of the parallel passage 141 are defined inside the frequency sensitive part case 540 by the partition disk 534. A partition disk 534 is arranged inside the cylindrical portion 544 of the case member 531, and the inner peripheral surface 550 of the cylindrical portion 544 of the case member 531 has a tapered shape in which the inner diameter is larger on the opening 549 side than on the bottom 541. It is. For this reason, the cylindrical portion 544 of the case member 531 has a tapered shape in which the inner diameter increases as the inner peripheral surface 550 moves away from the bottom portion 541 toward the partition disk 534 in the axial direction.

  The partitioning disk 534 can be displaced and deformed within a range in which the inner peripheral side moves between the protrusion 542 of the case member 531 and the disk 535 and the outer peripheral side moves between the support 543 and the flange 562 of the lid member 539. Has become. Here, the shortest in the axial direction between the support portion 543 supporting the axially intermediate portion of the disk 555 of the partition disk 534 from one axial side and the disk 535 supporting the inner peripheral side of the disk 555 from the other axial side. The distance is smaller than the axial thickness of the disk 555. Therefore, when the case chambers 571 and 572 have the same pressure, the disk 555 presses against the support portion 543 and the disk 535 with its own elastic force in a slightly deformed state.

  The partition disk 534 blocks the flow of the oil liquid between the case chambers 571 and 572 in the parallel passage 141 when the inner peripheral side of the disk 555 contacts the disk 535 over the entire circumference. In addition, the partition disk 534 allows the oil liquid to flow between the case chamber 571 and the case chamber 572, that is, the lower chamber 20, when the inner peripheral side of the disk 555 is separated from the disk 535. Therefore, the partition disk 534 and the disk 535 as a sheet portion thereof restrict the flow of the oil liquid from the case chamber 571 to the case chamber 572 and the lower chamber 20 in the parallel passage 141, while the lower chamber 20 and the case chamber A check valve 591 that allows the flow of the oil liquid from the 572 to the case chamber 571 is configured.

  In the extension stroke in which the pressure on the upper chamber 19 side is higher than the pressure on the lower chamber 20, the check valve 591 communicates with the parallel passage 141 through which the upper chamber 19 and the lower chamber 20 can communicate via the passage portion 38 of the piston 18. On the other hand, during the contraction stroke in which the pressure in the upper chamber 19 becomes lower than the pressure in the lower chamber 20, the parallel passage 141 is in a communicating state. The check valve 591 is a free valve in which the entire partition disk 534 as a valve body can move in the axial direction. The partition disk 534 is provided so as to be movable with respect to the case member 531, and forms a case chamber 571 between itself and the bottom 541 of the case member 531. The pilot chamber 401A includes a case member 356A different from the case member 531 and a main valve 121A.

  In the second embodiment, in the extension stroke in which the piston rod 21 moves to the extension side, the oil liquid flows from the upper chamber 19 to the lower chamber 20 via the passage 38 of the piston 18 shown in FIG. In the flow of the oil liquid from the upper chamber 19 through the passage portion 38 during the extension stroke, the damping force generating mechanism 41 including the valve seat portion 47 of the piston 18, the main valve 121, and the fixed orifice 92 is supplied from the passage portion 38. , There is a flow path that flows to the lower chamber 20 through the passage 125 between the piston 18 and the case member 356.

  In addition, the flow of the oil liquid from the upper chamber 19 through the passage 38 in the extension stroke flows in parallel with the above from the passage 38 through the passage 82 in the disk 50, and the intermediate chamber 85 and the disk. The damping force generation mechanism 41A including the valve seat portion 374 of the case member 356 and the main valve 121A flows through the pilot chamber 401 through the passage 416 to the back chamber 401, which is the back pressure chamber of the main valve 121. As described above, there is a flow path that flows to the lower chamber 20 via the passage 425 between the case member 356 and the case member 356A. Also in this case, the intermediate chamber 85 and the pilot chamber 401 have the same pressure because the passage 416 serving as a throttle between them is sufficiently wide.

  Further, the flow of the oil liquid from the upper chamber 19 through the passage portion 38 during the extension stroke flows in parallel with the above from the passage portion 38 through the passage portion 82 in the disk 50, and the intermediate chamber 85 and the disk portion. It flows to the pilot chamber 401A, which is the back pressure chamber of the main valve 121A, through the passage 416A of the main valve 355A, and to the lower chamber 20 through the damping force generating mechanism 145 including the valve seat portion 374A of the case member 356A and the disk valve 131. There is a channel.

  At the time of low-frequency input (large-amplitude input) to the shock absorber 1, the passage section 38, the passage section 82, the intermediate chamber 85, the passage section 416 A, the pilot chamber 401 A, the passage section 502, the passage section 491, the passage from the upper chamber 19. The amount of oil flowing into the case chamber 571 of the frequency sensitive section 530 via the section 582 and the passage section 581 is large, and the amount of flexure of the partition disk 534 is also large. It deforms until it abuts on 562 and the deflection is regulated. When the deflection of the partition disk 534 is regulated by the lid member 539 in this manner, the volume of the case chamber 571 cannot be increased, and thereafter the pressure in the pilot chamber 401A increases to a high pressure, and the damping force generating mechanism 41A The valve opening pressure of the main valve 121A increases. Until the main valve 121A opens, the pressure in the pilot chamber 401 also increases, so the valve opening pressure of the main valve 121 of the damping force generating mechanism 41 also increases. Therefore, the damping force has hard characteristics.

  At the time of this low frequency input, in a very low speed range where the piston speed is very low, the oil liquid entering the passage portion 38 from the upper chamber 19 is discharged from the fixed orifice of the main valve 121 in the closed state of the damping force generation mechanism 41. 92, and flows into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. The oil liquid entering the passage 38 flows from the passage 82, the intermediate chamber 85, the passage 416, and the pilot chamber 401 through the fixed orifice 92A of the main valve 121A in the closed state of the damping force generation mechanism 41A. , Flows into the lower chamber 20 via the passage 425 between the case member 356 and the case member 356A. For this reason, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the rate of increase of the damping force with respect to the increase of the piston speed becomes relatively high.

  In this state, when the piston speed is increased to increase the flow rate of the piston 18 through the passage 38, the oil flowing from the upper chamber 19 into the passage 38 opens the damping force generating mechanism 145, which is a hard valve. Then, it flows into the lower chamber 20. Then, at a predetermined first piston speed, the oil liquid from the upper chamber 19 flows to the pilot chamber 401 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 416, and the main body of the damping force generation mechanism 41A. The valve 121A is opened, and flows into the lower chamber 20 via the passage 425 between the case members 356 and 356A. Therefore, the characteristic of the damping force with respect to the piston speed becomes a valve characteristic, and the rate of increase of the damping force with respect to the increase of the piston speed is relatively low.

  When the piston speed is further increased, at a predetermined second piston speed, the oil liquid flowing from the upper chamber 19 into the passage portion 38 generates the damping force in addition to the flow of the damping force generating mechanism 41A that opens as described above. The main valve 121 of the mechanism 41 is opened, and flows into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. Thus, the rate of increase of the damping force with respect to the increase of the piston speed is further reduced.

  At the time of high-frequency input (small amplitude input) to the shock absorber 1, the passage section 38, the passage section 82, the intermediate chamber 85, the passage section 416 A, the pilot chamber 401 A, the passage section 502, the passage section 491, the passage section from the upper chamber 19. The amount of the oil liquid flowing into the case chamber 571 of the frequency sensitive section 530 via the path 582 and the passage section 581 is small, the amount of bending of the partition disk 534 is small, and the bending is not restricted even if the partitioning disk 534 comes into contact with the stopper section 559. Deform in the area. Therefore, the inflow of the oil liquid into the case chamber 571 can be absorbed by the bending of the partition disk 534, so that the pressure in the pilot chamber 401A that is always in communication with the case chamber 571 does not increase but becomes low, so that the main force of the damping force generating mechanism 41A is reduced. The valve opening pressure of the valve 121A is low. Further, by opening the main valve 121A from a low pressure in this way, the pressure in the pilot chamber 401 does not increase and becomes low, so that the valve opening pressure of the main valve 121 of the damping force generating mechanism 41 is also low. Therefore, the damping force has a soft characteristic.

  At the time of this high-frequency input, as in the case of the low-frequency input, in a very low speed range in which the piston speed is very low, the oil liquid entering the passage portion 38 from the upper chamber 19 is in a closed state of the damping force generation mechanism 41. It flows through the fixed orifice 92 of the main valve 121 and flows into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. The oil liquid entering the passage 38 flows from the passage 82, the intermediate chamber 85, the passage 416, and the pilot chamber 401 through the fixed orifice 92A of the main valve 121A in the closed state of the damping force generation mechanism 41A. , Flows into the lower chamber 20 via the passage 425 between the case member 356 and the case member 356A. For this reason, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the rate of increase of the damping force with respect to the increase of the piston speed becomes relatively high.

  From this state, when the piston speed is increased and the flow rate of the piston 18 in the passage 38 is increased, at a predetermined third piston speed, the oil liquid from the upper chamber 19 flows through the passage 38, the passage 82, The air flows into the pilot chamber 401 through the chamber 85 and the passage 416, opens the main valve 121 A of the damping force generating mechanism 41 A, and passes through the lower chamber 20 through the passage 425 between the case member 356 and the case member 356 A. Flows to Therefore, the characteristic of the damping force with respect to the piston speed becomes a valve characteristic, and the rate of increase of the damping force with respect to the increase of the piston speed is relatively low.

  When the piston speed is further increased, at a predetermined fourth piston speed, the oil liquid flowing from the upper chamber 19 into the passage portion 38 generates the damping force in addition to the flow of the damping force generating mechanism 41A that opens as described above. The main valve 121 of the mechanism 41 is opened, and flows into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. Thus, the rate of increase of the damping force with respect to the increase of the piston speed is further reduced.

  Here, in the frequency responsive unit 530, during the contraction stroke, the pressure in the lower chamber 20 increases, and the pressure in the case chamber 572 becomes higher than the pressure in the case chamber 571. As a result, the partition disk 534 as a valve body of the check valve 591 is deformed around the support portion 543 of the case member 356 as a fulcrum, and is separated from the disk 535 as a valve seat of the check valve 591. As a result, the check valve 591 opens the passage 140 and allows the oil liquid to flow from the lower chamber 20 to the upper chamber 19 via the passage 140. At this time, the partition disk 534 is separated from the disk 535 so that the differential pressure is eliminated, and further movement is suppressed.

  The shock absorber 1 according to the second embodiment includes a main valve 121 that is provided in the passage 130 and suppresses the flow of the oil liquid from the upper chamber 19 to the lower chamber 20 by sliding the piston 18 to generate a damping force; A first damping force generating mechanism 41 having a pilot chamber 401 for applying pressure to the valve 121 in a valve closing direction is provided. In addition, at least a part of the passage 140 parallel to the passage 130 is formed with a bottomed cylindrical case member 531 formed therein, and the bottom member 541 of the case member 531 is provided movably with respect to the case member 531. And a partition disk 534 forming a case chamber 571 therebetween. By forming the case chamber 571 by the case member 531 and the partition disk 534, the damping force can be changed in response to the frequency. Then, in addition to the first damping force generation mechanism 41, a main valve 121A that generates a damping force by suppressing the flow of the oil liquid from the pilot chamber 401 to the lower chamber 20, and a pressure is applied to the main valve 121A in the valve closing direction. A second damping force generating mechanism 41A having a pilot chamber 401A to be operated. Thereby, the damping force can be switched to a plurality of stages in response to an increase in the piston speed. Therefore, the damping force characteristics can be made smooth. As a result, it is possible to suppress a decrease in ride comfort and generation of abnormal noise.

  Further, since pilot chamber 401A is formed of case member 356A different from case member 531 of frequency sensitive portion 530 and main valve 121A, frequency sensitive portion 530 is easily assembled to piston rod 21. Can be.

  Further, since the cylindrical portion 544 of the case member 531 has a tapered shape in which the inner diameter increases as the distance from the bottom portion 541 toward the partition disk 534 increases, friction when the seal portion 558 of the partition disk 534 slides can be reduced. it can.

  That is, the seal portion 558 of the partition disk 534 is provided on the disk 555 facing the bottom 541 side opposite to the lift direction of the partition disk 534 when the pressure in the case chamber 571 increases. Therefore, when the inner diameter of the cylindrical portion 544 is straight, as the partition disk 534 is lifted away from the bottom portion 541 by the pressure increase of the case chamber 571, the partition disk 534 is pressed by the pressure of the case chamber 571, and The interference with 544 increases, and the friction of sliding of the seal portion 558 with respect to the cylindrical portion 544 increases. On the other hand, by making the cylindrical portion 544 tapered so that the inner diameter of the cylindrical portion 544 increases in the direction of the lift of the partition disk 534, the interference of the seal portion 558 to the cylindrical portion 544 during the lift can be excessive. It is possible to prevent excessive friction.

  FIG. 8 shows an analysis result of a characteristic of the cylindrical portion 544 according to the second embodiment with respect to the pressure load of the tightening force received from the seal portion 558. As shown by the broken line Y1 in FIG. 8, when the pressure load on the partition disk 534 received from the case chamber 571 increases, the tightening force (that is, friction) of the cylindrical portion 544 received from the seal portion 558 increases. As compared with the case where the inner diameter of the cylindrical portion 544 shown by the solid line Y2 is a constant straight shape, the tension applied to the cylindrical portion 544 can be reduced.

  As described above, since the partition disk 534 can smoothly move without being caught by the cylindrical portion 544, the damping force characteristics can be made smooth. As a result, it is possible to suppress a decrease in ride comfort and generation of abnormal noise.

  Further, by making the cylindrical portion 544 of the case member 531 into a tapered shape so that the inner diameter of the cylindrical portion 544 increases in the direction of the partition disk 534, assemblability can be improved. That is, by forming the cylindrical portion 544 of the case member 531 into a tapered shape having a large diameter on the opening 549 side, the partition disk 534 can be easily fitted into the cylindrical portion 544 from the opening 549 side. At this time, by setting the inner diameter of the opening 549 to be larger than the outer diameter of the partition disk 534, the seal portion 558 is less likely to be caught by the opening 549 of the cylindrical portion 544 when the partition disk 534 is incorporated into the case member 531. The fitting becomes easy, and the assembling property can be improved.

[Third embodiment]
Next, the third embodiment will be described mainly with reference to FIG. 9 focusing on the differences from the second embodiment. Note that parts common to the second embodiment are denoted by the same names and the same reference numerals.

  In the third embodiment, the main valve 121 of the damping force generating mechanism 41 has a plurality of disks 601 between the disk 51 and the pilot valve 352. Further, the damping force generating mechanism 41 does not have the disk 355 of the second embodiment. Further, the disk 50A, the disk 51A, the pilot valve 352A, the disk 353A, the disk 355A, and the case member 356A of the damping force generating mechanism 41A of the second embodiment are not provided. The large-diameter hole 376 of the case member 356 is formed on the side opposite to the disk 353 in the axial direction, and the small-diameter hole 375 is formed on the disk 353 side in the axial direction. Then, the disk 500 is in contact with the case member 356 and the disk valve 131, and the passage portion 502 in the notch 501 defines the intermediate chamber 85 including the inside of the large-diameter hole 376 of the case member 356, and the pilot chamber 401. Is always communicated with. A passage portion 502 of the disk 500 is a throttle provided between the intermediate chamber 85 and the pilot chamber 401, that is, an orifice.

  On the opposite side of the disk valve 131 from the disk 500, there are provided a disk 511, a disk 512 and a frequency sensitive part 530 similar to the second embodiment. In the third embodiment, the large-diameter hole 546 of the case member 531 communicates directly with the passage groove 30 of the piston rod 21, whereby the case chamber 571 always communicates with the intermediate chamber 85. ing.

  In the third embodiment, in the extension stroke in which the piston rod 21 moves to the extension side, the oil liquid flows from the upper chamber 19 to the lower chamber 20 via the passage 38 of the piston 18. In the flow of the oil liquid from the upper chamber 19 through the passage portion 38 during the extension stroke, the damping force generating mechanism 41 including the valve seat portion 47 of the piston 18, the main valve 121, and the fixed orifice 92 is supplied from the passage portion 38. , There is a flow path that flows to the lower chamber 20 through the passage 125 between the piston 18 and the case member 356.

  In addition, the flow of the oil liquid from the upper chamber 19 through the passage 38 during the extension stroke flows in parallel with the above from the passage 38 through the passage 82 in the disk 50 and through the intermediate chamber 85. Flows through the passage portion 502 of the disc 500 to the pilot chamber 401 which is a back pressure chamber of the main valve 121, passes through the valve seat portion 374 of the case member 356 and the damping force generating mechanism 145 including the disc valve 131, and then flows into the lower chamber 20. There is a channel that flows to

  At the time of low-frequency input (large-amplitude input) to the shock absorber 1, oil flowing from the upper chamber 19 to the case chamber 571 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 581 of the frequency sensitive section 530. The liquid volume is large and the amount of deflection of the partition disk 534 is also large, and the partition disk 534 is deformed until the stopper portion 559 contacts the flange portion 562 of the lid member 539 and the bending is regulated. With the deflection of the partition disk 534 thus regulated by the lid member 539, the oil liquid from the upper chamber 19 flows to the pilot chamber 401 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 502. Flow in. Then, the pressure in the pilot chamber 401 increases to a high pressure, and the valve opening pressure of the main valve 121 of the damping force generating mechanism 41 increases. Therefore, the damping force has hard characteristics.

  At the time of this low frequency input, in a very low speed range where the piston speed is very low, the oil liquid entering the passage portion 38 from the upper chamber 19 is discharged from the fixed orifice of the main valve 121 in the closed state of the damping force generation mechanism 41. 92, and flows into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. For this reason, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the rate of increase of the damping force with respect to the increase of the piston speed becomes relatively high.

  When the piston speed is increased from this state, the oil liquid flowing into the passage portion 38 from the upper chamber 19 flows into the lower chamber 20 by opening the damping force generating mechanism 145 which is a hard valve. Thereafter, when the flow rate flowing through the passage portion 38 of the piston 18 is increased, at a predetermined piston speed, the oil liquid from the upper chamber 19 opens the main valve 121 of the damping force generating mechanism 41, and It flows into the lower chamber 20 through the passage 125 between the case member 356. Therefore, the rate of increase of the damping force is relatively low with respect to the increase of the piston speed.

  At the time of high frequency input (small amplitude input) to the shock absorber 1, the amount of oil flowing from the upper chamber 19 to the case chamber 571 via the passage 38, the passage 82, the intermediate chamber 85, and the passage 581 is small. The amount of bending of the disk 534 is also reduced, and the disk 534 is deformed within a range where the bending is not restricted even when the disk 534 comes into contact with the stopper portion 559. Therefore, the inflow of the oil liquid into the case chamber 571 can be absorbed by the bending of the partition disk 534, so that the pressure in the pilot chamber 401 which is always in communication with the case chamber 571 does not increase but becomes low pressure. The valve opening pressure of the valve 121 is low. Therefore, the damping force has a soft characteristic.

  At the time of this high-frequency input, as in the case of the low-frequency input, in a very low speed range in which the piston speed is very low, the oil liquid entering the passage portion 38 from the upper chamber 19 is in a closed state of the damping force generation mechanism 41. It flows through the fixed orifice 92 of the main valve 121 and flows into the lower chamber 20 via the passage 125 between the piston 18 and the case member 356. For this reason, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the rate of increase of the damping force with respect to the increase of the piston speed becomes relatively high.

  From this state, when the piston speed is increased to increase the flow rate flowing through the passage portion 38 of the piston 18, the oil flowing from the upper chamber 19 into the passage portion 38 at a predetermined piston speed is reduced by the damping force generation mechanism 41. The main valve 121 is opened, and flows into the lower chamber 20 through the passage 125 between the piston 18 and the case member 356. Therefore, the characteristic of the damping force with respect to the piston speed becomes a valve characteristic, and the rate of increase of the damping force with respect to the increase of the piston speed is relatively low.

  According to the shock absorber 1 of the third embodiment, as in the second embodiment, the cylindrical portion 544 of the case member 531 has a tapered shape in which the inner diameter increases as the distance from the bottom portion 541 to the partition disk 534 side in the axial direction increases. Therefore, friction when the seal portion 558 of the partition disk 534 slides can be reduced. Therefore, since the partition disk 534 can move smoothly without being caught on the cylindrical portion 544, the damping force characteristics can be made smooth. As a result, it is possible to suppress a decrease in ride comfort and generation of abnormal noise.

  Further, since the cylindrical portion 544 of the case member 531 is tapered so that the inner diameter increases in the direction of the partition disk 534, the partition disk 534 can be easily fitted into the cylindrical portion 544, and the assembling property can be improved. it can.

  The above-described embodiment shows an example in which the present invention is applied to a double-cylinder hydraulic shock absorber. However, the present invention is not limited to this, and the outer cylinder is eliminated and the lower chamber 20 in the cylinder 2 slides in the opposite side to the upper chamber 19. It may be used for a monotube type hydraulic shock absorber that forms a gas chamber with a movable partition, and may be used for any shock absorber including a pressure control valve using a packing valve having a structure in which a seal member is provided on a disk. it can. Of course, it is also possible to apply the present invention to the above-described contraction-side damping force generating mechanism 42 or to apply the present invention to the above-described base valve 25. Further, the present invention is also applicable to a case where an oil passage communicating with the inside of the cylinder 2 is provided outside the cylinder 2 and a damping force generating mechanism is provided in this oil passage. Further, in the above embodiment, the hydraulic shock absorber is described as an example, but water or air can be used as the fluid.

  In the first aspect of the embodiment described above, a cylinder in which a working fluid is sealed, a piston slidably provided inside the cylinder and defining two chambers in the cylinder, and one end side portion are provided. A piston rod fixed to the piston inside the cylinder and the other end of which protrudes to the outside of the cylinder via a rod guide, and a first fluid from which a working fluid flows out of one chamber in the cylinder by movement of the piston. A passage, a second passage provided in parallel with the first passage, a first damping force generating mechanism provided in the first passage to generate a damping force, and at least a portion of the second passage is formed inside the passage. A first cylindrical housing having a bottom and a disk movably provided with respect to the housing and forming a housing inner chamber between the bottom of the housing and the first damping force. The raw mechanism suppresses the flow of the working fluid from the upstream chamber to the downstream chamber by sliding the piston to generate a damping force, and applies pressure to the first main valve in a valve closing direction. A second damping force generating mechanism that suppresses the flow of the working fluid from the first pilot chamber to the downstream chamber to generate a damping force, wherein the second damping force generating mechanism is provided. A second main valve that suppresses the flow of the working fluid from the first pilot chamber to the downstream chamber to generate a damping force; and a second pilot chamber that applies pressure to the second main valve in a valve closing direction. And This makes it possible to smooth the damping force characteristics.

  In a second aspect based on the first aspect, the second pilot chamber includes the housing, the disk, and the second main valve. Thereby, the number of parts can be reduced, and the cost can be reduced.

  In a third aspect based on the first aspect, the second pilot chamber includes a case separate from the housing and the second main valve. This makes it easy to assemble.

  According to a fourth aspect, in any one of the first to third aspects, the cylindrical portion of the housing has a tapered shape in which the inner diameter increases as the distance from the bottom toward the disk increases. Thereby, the movement of the disk with respect to the cylindrical portion of the housing becomes smooth, and the damping force characteristics can be made smooth.

  In a fifth aspect, a cylinder in which a working fluid is sealed, a piston slidably provided inside the cylinder and defining two chambers in the cylinder, and one end portion of the piston inside the cylinder A piston rod whose other end is projected to the outside of the cylinder via a rod guide, a first passage through which a working fluid flows out of one chamber in the cylinder by movement of the piston, and a first passage. A second passage provided in parallel with the first passage, a damping force generating mechanism provided in the first passage for generating a damping force, and a bottomed cylindrical housing in which at least a part of the second passage is formed. A disk movably provided with respect to the housing and forming a housing inner chamber between the housing and the bottom of the housing, wherein the damping force generating mechanism slides the piston. Accordingly, a main valve that suppresses the flow of the working fluid from the upstream chamber to the downstream chamber to generate a damping force, and a pilot chamber that applies pressure to the main valve in a valve closing direction, is provided. , The inner diameter increases as the distance from the bottom to the disk side increases. Thereby, the movement of the disk with respect to the cylindrical portion of the housing becomes smooth, and the damping force characteristics can be made smooth.

DESCRIPTION OF SYMBOLS 1 Cushion 2 Cylinder 18 Piston 19 Upper chamber (upstream chamber)
20 lower room (downstream room)
21 piston rod 22 rod guide 41 damping force generating mechanism (first damping force generating mechanism)
41A damping force generation mechanism (second damping force generation mechanism)
52 Pilot valve (second main valve)
56 Case member (housing)
69 Partition disk (disk)
71 Bottom 101 Pilot room (second pilot room)
102 Variable room (inside the housing)
121 Main valve (first main valve)
121A main valve (second main valve)
130 passage (first passage)
140 passage (second passage)
356A Case member (case)
401 Pilot room (first pilot room)
401A pilot room (second pilot room)
441 Damping Force Generating Mechanism (Second Damping Force Generating Mechanism)
531 Case member (housing)
534 Partition disk (disk)
540 Frequency sensitive part case 541 Bottom part 544 Cylindrical part 571 Case room (Housing inner room)

Claims (5)

A cylinder filled with a working fluid,
A piston slidably provided inside the cylinder and defining two chambers in the cylinder;
A piston rod having one end portion fixed to the piston inside the cylinder and the other end portion protruding outside the cylinder via a rod guide;
A first passage through which a working fluid flows out of one chamber in the cylinder by movement of the piston;
A second passage provided in parallel with the first passage;
A first damping force generating mechanism provided in the first passage to generate a damping force;
A bottomed cylindrical housing in which at least a part of the second passage is formed;
A disk movably provided with respect to the housing and forming a housing inner chamber between the disk and the bottom of the housing;
Has,
The first damping force generating mechanism includes:
A first main valve that generates a damping force by suppressing the flow of the working fluid from the upstream chamber to the downstream chamber by sliding the piston;
A first pilot chamber for applying pressure to the first main valve in a valve closing direction;
With
A second damping force generating mechanism that suppresses the flow of the working fluid from the first pilot chamber to the downstream chamber to generate a damping force is provided;
The second damping force generating mechanism includes:
A second main valve that suppresses the flow of the working fluid from the first pilot chamber to the downstream chamber to generate a damping force;
A second pilot chamber for applying pressure to the second main valve in a valve closing direction;
A shock absorber characterized by comprising:   The shock absorber according to claim 1, wherein the second pilot chamber includes the housing, the disk, and the second main valve.   The shock absorber according to claim 1, wherein the second pilot chamber includes a case different from the housing and the second main valve.   The shock absorber according to any one of claims 1 to 3, wherein the cylindrical portion of the housing has a tapered shape in which the inner diameter increases as the distance from the bottom to the disk side increases. A cylinder filled with a working fluid,
A piston slidably provided inside the cylinder and defining two chambers in the cylinder;
A piston rod having one end portion fixed to the piston inside the cylinder and the other end portion protruding outside the cylinder via a rod guide;
A first passage through which a working fluid flows out of one chamber in the cylinder by movement of the piston;
A second passage provided in parallel with the first passage;
A damping force generating mechanism that is provided in the first passage and generates a damping force;
A bottomed cylindrical housing in which at least a part of the second passage is formed;
A disk movably provided with respect to the housing and forming a housing inner chamber between the disk and the bottom of the housing;
Has,
The damping force generation mechanism,
A main valve that generates a damping force by suppressing the flow of the working fluid from the upstream chamber to the downstream chamber by sliding the piston,
A pilot chamber for applying pressure to the main valve in a valve closing direction,
With
The shock absorber according to claim 1, wherein the cylindrical portion of the housing has a tapered shape in which the inner diameter increases as the distance from the bottom to the disk side increases.

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