JP7109293B2 - buffer - Google Patents

Description

The present invention relates to shock absorbers.

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

WO2017/047661

Buffers are required to have smooth damping force characteristics.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shock absorber capable of smoothing damping force characteristics.

In order to achieve the above object, one aspect of the present invention is to provide a first passage through which working fluid flows from one chamber in a cylinder due to 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 to generate a damping force; a bottomed tubular housing in which at least part of the second passage is formed; and movable with respect to the housing. and a disc provided in the housing forming a housing inner chamber between itself and the bottom of the housing, wherein the first damping force generating mechanism moves the working fluid from the upstream chamber to the downstream chamber by sliding of the piston. A first main valve that suppresses a flow to generate a damping force, and a first pilot chamber that 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 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. and a second pilot chamber for applying pressure to the second main valve in a valve-closing direction. a passage formed to communicate between the second pilot chamber and the inside of the cylinder ; a third damping force generating mechanism that suppresses flow of working fluid from the passage into the cylinder to generate a damping force ; It has

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

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the shock absorber of 1st Embodiment which concerns on this invention. It is a partial cross-sectional view showing the vicinity of a piston of the shock absorber of the first embodiment according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a half sectional view which shows the principal part of the shock absorber of 1st Embodiment which concerns on this invention. 1 is a hydraulic circuit diagram of a shock absorber of a first embodiment according to the present invention; FIG. FIG. 4 is a characteristic diagram showing damping force characteristics of the shock absorber of the first embodiment according to the present invention; It is a half sectional view showing the principal part of the shock absorber of a 2nd embodiment concerning the present invention. FIG. 10 is a half sectional view showing the periphery of the frequency sensitive part of the shock absorber of the second embodiment according to the present invention; FIG. 10 is a characteristic diagram of the compression force with respect to the pressure load that the cylindrical portion of the case member of the shock absorber according to the second embodiment of the present invention receives from the seal portion of the partition disk; It is a half sectional view showing the principal part of the 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. 1 to 5. FIG. In the following description, for convenience of explanation, the upper side in the drawings will be referred to as "upper" and the lower side in the drawings will be referred to as "lower".

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

The outer cylinder 4 is composed of a cylindrical body member 11 and a bottom member 12 that is fitted and fixed to the lower side of the body member 11 to close the lower portion of the body member 11 . A mounting eye 13 is fixed to the bottom member 12 on the outside 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 put on the body member 11 so 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. is crimped radially inward and 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, an upper chamber 19 as one cylinder inner chamber and a lower chamber 20 as the other cylinder inner chamber, in the inner cylinder 3 . An upper chamber 19 and a lower chamber 20 in the inner cylinder 3 are filled with oil as a working fluid, and a reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4 is filled with oil and gas as working fluids. is enclosed.

The shock absorber 1 includes a piston rod 21 whose one end portion is arranged 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 passes through the upper chamber 19 and does not pass through 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 .

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

A rod guide 22 is fitted to the upper opening sides 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 , which is the outer side of the cylinder 2 . there is A friction member 24 is provided between the rod guide 22 and the seal member 23 . The rod guide 22, the sealing member 23, and the friction member 24 are all annular, and the piston rod 21 is slidably inserted through each of the rod guide 22, the friction member 24, and the sealing member 23. It extends from the inside of the cylinder 2 to the outside. The piston rod 21 has one end portion fixed to the piston 18 inside the cylinder 2 and the other end portion protruding outside the cylinder 2 via a rod guide 22 , a friction member 24 and a seal member 23 .

The rod guide 22 supports the piston rod 21 axially movably while restricting its radial movement, and guides the movement of the piston rod 21 . The seal member 23 is in close contact with the outer cylinder 4 at its outer peripheral portion, and slidably contacts the outer peripheral portion of the piston rod 21 moving in the axial direction at its inner peripheral portion. It prevents the high-pressure gas and oil in the internal reservoir chamber 6 from leaking to the outside. The friction member 24 slidably contacts the outer peripheral portion of the piston rod 21 at its inner peripheral portion to generate frictional resistance on the piston rod 21 . It should be noted that the friction member 24 is not intended for sealing.

The outer circumference of the rod guide 22 has a stepped shape in which the diameter of the upper portion is larger than that of the lower portion. It is fitted to the inner periphery of the upper part of 4 . A base valve 25 is installed on the bottom member 12 of the outer cylinder 4 to define the lower chamber 20 and the reservoir chamber 6, and the inner peripheral portion of the lower end of the inner cylinder 3 is fitted to the base valve 25. ing. A portion (not shown) of the upper end portion of the outer cylinder 4 is crimped radially inward, and this crimped portion and the rod guide 22 sandwich a sealing 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 portion 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 portion 28 is arranged in the cylinder 2 and connected to the piston 18 and the like. . An end portion of the main shaft portion 27 on the mounting shaft portion 28 side forms a shaft stepped portion 29 extending in the direction perpendicular to the axis. A passage groove 30 extending in the axial direction is formed in the outer peripheral portion of the mounting shaft portion 28 at an intermediate position in the axial direction, and a male thread 31 is formed at the tip position on the side 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 perpendicular to the central axis of the piston rod 21. It is formed like an eggplant.

The piston rod 21 is provided with a ring-shaped stopper member 32 and a shock absorbing member 33 at a portion of the main shaft portion 27 between the piston 18 and the rod guide 22 . The stopper member 32 has the piston rod 21 inserted through its inner peripheral side, and is fixed by caulking in a fixing groove 34 recessed radially inward of the main shaft portion 27 . The cushioning body 33 also has the piston rod 21 inserted therein, and is arranged between the stopper member 32 and the rod guide 22 .

For example, the shock absorber 1 is supported by the vehicle body with the portion of the piston rod 21 protruding from the cylinder 2 arranged on the upper part, and the mounting eye 13 on the cylinder 2 side is arranged on the lower part and connected to the 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 during running, the relative positions of the cylinder 2 and the piston rod 21 change with the vibration. is suppressed by the fluid resistance of As will be 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 vibration, and suppressing the vibration improves ride comfort. is improved. Between the cylinder 2 and the piston rod 21, not only the vibration generated by the wheels, but also the inertial force and the centrifugal force generated in the vehicle body as the vehicle runs. For example, when the running direction is changed by operating the steering wheel, a centrifugal force is generated in the vehicle body, and a force based on this centrifugal force acts between the cylinder 2 and the piston rod 21 . As will be described below, the shock absorber 1 has good characteristics against vibrations caused by forces generated in the vehicle body as the vehicle travels, and high stability can be obtained while the vehicle travels.

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 attached to the outer peripheral surface of the piston body 35 and slides inside the inner cylinder 3 . It is composed of a sliding member 36 made of resin.

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

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

The passage holes 39, which constitute the remaining half shown in FIG. ) is open radially outward and one axial side (upper side in FIG. 2) is open radially inward.

A damping force generating mechanism 42 that opens and closes the passage portion 40 to generate a damping force is provided in the passage portion 40 in the passage hole 39 . The damping force generating mechanism 42 is arranged on the upper chamber 19 side, which is the other end side of the piston 18 in the axial direction, and is attached to the piston rod 21 . By arranging the damping force generating mechanism 42 on the upper chamber 19 side, the plurality of passages 40 are arranged on the downstream side from the lower chamber 20 which is the upstream side in the movement of the piston 18 toward the lower chamber 20 side, that is, the compression stroke. It becomes a passage through which the oil flows out toward the upper chamber 19 . A damping force generating mechanism 42 provided for these passage portions 40 is a compression side damping force generating mechanism that suppresses the flow of oil from the compression side passage portion 40 to the upper chamber 19 to generate a damping force. It has become.

As described above, the passage portions 38 in the plurality of passage holes 37 and the passage portions 40 in the plurality of passage holes 39 are arranged such that the hydraulic fluid, which is the working fluid, flows between the upper chamber 19 and the lower chamber 20 due to the movement of the piston 18. Hydraulic fluid passes through the passage portion 38 when the piston rod 21 and the piston 18 move toward the extension side (upper side in FIG. 2), and the passage portion 40 passes the piston rod 21 and the piston. The oil passes through when 18 moves to the contraction side (lower side in FIG. 2).

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

At the end of the piston body 35 on the lower chamber 20 side in the axial direction, an annular valve seat portion forming part of the damping force generating mechanism 41 is arranged radially outward of the opening of the passage hole 37 on the lower chamber 20 side. 47 is formed. The insertion hole 44 has a large-diameter hole portion 46 located closer to the valve seat portion 47 in the axial direction than the small-diameter hole portion 45 . At the end of the piston body 35 on the upper chamber 19 side in the axial direction, an annular valve forming a part of the damping force generating mechanism 42 is provided radially outward of 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 whose height in the axial direction is lower than that of the valve seat portion 47, and the contraction side passage hole 39 is formed in this stepped portion. 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 forms a step whose height in the axial direction is lower than that of the valve seat portion 48. The upper chamber 19 side opening of the passage portion 38 is arranged in the side passage hole 37 .

As shown in FIG. 3, on the valve seat portion 47 side of the piston 18, one disk 50, one disk 51, one pilot valve 352, and one pilot valve 352 are arranged in order from the piston 18 side in the axial direction. One disc 353, one disc 355, one case member 356, one pilot valve 52 (second main valve), multiple discs 53, one spring disc 54, and one A disc 55, a case member 56 (housing), a plurality of discs 57, a disc 58, a disc 59, and an annular member 60 are attached to the piston rod 21. A shaft portion 28 is fitted inside each of them. Disks 50, 51, 53, 55, 57-59, 353, 355, spring disk 54, case members 56, 356 and 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 perforated circular flat plate shape with a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted. ing. The spring disk 54, the pilot valves 52, 352, and the case members 56, 356 all have an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The case member 356 has a bottomed tubular shape and an annular shape. A cylindrical inner cylindrical portion 372 protruding to both sides along the axial direction of the bottom portion 371, and a cylindrical outer cylindrical portion protruding to one side along the axial direction of the bottom portion 371 from the outer peripheral edge of the bottom portion 371. 373 , and an annular valve seat portion 374 protruding from a radially intermediate position of the bottom portion 371 toward the opposite side of the outer cylindrical portion 373 along the axial direction of the bottom portion 371 . The mounting shaft portion 28 of the piston rod 21 passes through the through hole 370 of the case member 356 . The bottom portion 371 , the inner cylindrical portion 372 , the outer cylindrical portion 373 , and the valve seat portion 374 are arranged coaxially, and the central axis of these is the central axis of the case member 356 .

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

The through hole 370 on the inner circumference of the inner cylindrical portion 372 is formed with a small diameter hole portion 375 on the side of the valve seat portion 374 in the axial direction, into which the mounting shaft portion 28 of the piston rod 21 is fitted. A large-diameter hole portion 376 having a diameter larger than that of the small-diameter hole portion 375 is formed on the side opposite to the seat portion 374 . A part of the mounting shaft portion 28 of the piston rod 21 inserted through the through hole 370 is arranged in the case member 356 in the axial direction. The interior of the large-diameter hole 46 of the piston body 35, the interior of the passage groove 30 of the mounting shaft 28, and the interior of the large-diameter hole 376 of the case member 356 are always in communication, and these constitute an intermediate chamber 85. there is

The disc 50 has an outer diameter smaller than the inner diameter of the valve seat portion 47 . The disk 50 is formed with a notch 81 that extends radially outward from the inner peripheral edge portion that fits onto the mounting shaft portion 28 of the piston rod 21 . A passage portion 82 in the notch 81 is in constant communication with the passage portion 38 of the piston 18 on the one hand and with the intermediate chamber 85 on the other hand. A passage portion 82 in the notch 81 serves as a restriction, 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 disc 51 has an outer diameter substantially equal to the outer diameter of the valve seat portion 47 of the piston 18 . The disk 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 crosses the valve seat portion 47 in the radial direction. Therefore, the inner side of the notch 91 serves as a fixed orifice 92 that always communicates the passage portion 38 with the lower chamber 20 .

The pilot valve 352 consists of a metal disk 395 and a rubber sealing member 396 fixed to the disk 395 . The disc 395 has a perforated circular flat plate shape with a constant thickness in 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 disc 51 . . The seal member 396 is fixed to the outer peripheral side of the disk 395 in the axial direction opposite to the piston 18 and has an annular shape. In other words, the pilot valve 352 has an annular seal member 396 on its outer periphery.

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

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

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

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

The case member 56 is cylindrical and annular with a bottom, and has a perforated disc-shaped bottom portion 71 in which a through hole 70 penetrating in the thickness direction is formed in the center in the radial direction. A cylindrical inner cylindrical portion 72 protruding to both sides along the axial direction of the bottom portion 71 , and a cylindrical outer cylindrical portion protruding to one side along the axial direction of the bottom portion 71 from the outer peripheral edge portion of the bottom portion 71 . 73 , and an annular valve seat portion 74 protruding from a radially intermediate position of the bottom portion 71 toward the opposite side of the outer cylindrical portion 73 along the axial direction of the bottom portion 71 . The mounting shaft portion 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 arranged coaxially, and the central axis of these is the central axis of the case member 56 .

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

The bottom portion 71 has a tapered surface 65 on the side of the axially outer cylindrical portion 73 and inside the disk contact portion 62 in the radial direction. A portion 66 is formed. The tapered portion 66 is provided at the radial end portion of the bottom portion 71 on the side of the inner cylindrical portion 72 . The disk contact portion 62 , the recessed portion 64 and the tapered portion 66 are arranged coaxially with the central axis of the case member 56 .

A through hole 67 is formed in the bottom portion 71 so as to extend through the bottom portion 71 along the axial direction at the deepest bottom position of the recess portion 64 , that is, at the center position of the width of the recess portion 64 in the radial direction. 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 portion is shown in FIG. 3 because of the partial cross section). At least one through hole 67 may be provided in the bottom portion 71 . The through hole 67 is arranged outside the valve seat portion 74 in the radial direction of the bottom portion 71 . A passage portion 103 in the through hole 67 always communicates with the lower chamber 20 .

An annular partition disk 69 (disk) is arranged in the case member 56 so as to face the bottom portion 71 . The partition disk 69 is a flat plate made of metal, and has an outer diameter slightly smaller than the maximum diameter of the seat surface 61 of the disk contact portion 62 , in other words, the inner diameter of the outer cylindrical portion 73 and the maximum diameter of the stopper surface 63 . Its inner diameter is slightly larger than the minimum diameter of the seat surface 61 of the disc 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 restrained from moving in the radial direction relative to the case member 56 and is movable in the axial direction. , and covers the entire stopper surface 63 . The mounting shaft portion 28 of the piston rod 21 also passes through the partition disc 69 .

A through hole 67 formed at the deepest position of the concave portion 64 of the bottom portion 71 is provided so as to face the division disk 69 in the radial direction and face the axial direction. The partition disc 69 closes the through hole 67 by making surface contact with the seat surface 61 and opens the through hole 67 by separating from the seat surface 61 . In addition, the partition disk 69 is elastically deformable so as to enter the recess 64 , and at that time, comes into contact with the boundary peripheral edge portions on both sides in the radial direction between the stopper surface 63 and the seat surface 61 or the entire surface of the stopper surface 63 . to maintain the closed state of the through hole 67 .

A through hole 68 is formed in the bottom portion 71 at an intermediate position in the radial direction of the tapered portion 66 so as to pass through the case member 56 along the axial direction. A plurality of through-holes 68 are formed at intervals in the circumferential direction of the bottom portion 71 (only one portion is shown in FIG. 3 due to the partial cross section). The through hole 68 is arranged between the valve seat portion 74 and the inner cylindrical portion 72 in the radial direction of the bottom portion 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 central through-hole 70 of the inner cylindrical portion 72 is formed with a small-diameter hole portion 75 on the side of the axial valve seat portion 74, into which the mounting shaft portion 28 of the piston rod 21 is fitted. A large-diameter hole portion 76 having a diameter larger than that of the small-diameter hole portion 75 is formed on the opposite side of the portion 74 . The inside of the large-diameter hole portion 76 always communicates with the inside of the passage groove 30 of the mounting shaft portion 28 . Therefore, the inside of the large-diameter hole portion 76 also forms an intermediate chamber 85 together with the large-diameter hole portion 46 of the piston body 35 , the passage groove 30 of the mounting shaft portion 28 , and the large-diameter hole portion 376 of the case member 356 . A part of the mounting shaft portion 28 of the piston rod 21 inserted through the through hole 70 is arranged in the case member 56 in the axial direction.

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

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

With the partition disk 69 closing the passage 103 in the through hole 67 , the space between the pilot valve 52 , the case member 56 and the partition disk 69 is a pilot chamber 101 (second pilot chamber) that serves as a back pressure chamber of the pilot valve 52 . room). In other words, the pilot chamber 101 is composed of the case member 56 , the partition disc 69 and the pilot valve 52 . In this state, the variable chamber 102 (housing inner chamber) communicating with the lower chamber 20 is formed between the recess 64 of the bottom portion 71 of the case member 56 and the partition disk 69 . In other words, the partition disc 69 forms the variable chamber 102 with the bottom portion 71 of the case member 56 . Therefore, these two pilot chambers 101 and variable chamber 102 are provided within the case member 56 so as to be defined by the partition disk 69 .

The variable chamber 102 communicates with the passage portion 103 and constantly communicates with the lower chamber 20 via the passage portion 103 . The pilot chamber 101, the variable chamber 102, and the partition disc 69 that partitions them form a frequency sensitive portion 104 that responds to the frequency of the reciprocating motion of the piston 18 (hereinafter referred to as piston frequency) to vary the damping force. there is

The partition disc 69 has a state in which both the inner peripheral side and the outer peripheral side are in surface contact with the seat surface 61 of the disc contact portion 62 over the entire periphery, and both the inner peripheral side and the outer peripheral side are in contact with the seat surface 61 over the entire periphery. Circulation of the oil between the pilot chamber 101 and the variable chamber 102 is blocked in the state of contacting the boundary edges on both sides with the surface 63 and the state of contacting the stopper surface 63 over the entire circumference. Further, the partition disk 69 allows the oil to flow between the pilot chamber 101 and the variable chamber 102 when separated from the bottom portion 71 . The spring disk 54 urges the partition disk 69 to abut against the seat surface 61, so that the spring disk 54, the partition disk 69, the disk contact portion 62 and the recess 64 of the case member 56 are aligned. A check that restricts the flow of hydraulic fluid from the pilot chamber 101 side to the variable chamber 102 side, i.e., the lower chamber 20 side, while permitting the hydraulic fluid flow from the variable chamber 102 side, i.e., the lower chamber 20 side, to the pilot chamber 101 side. It constitutes the valve 105 .

The partition disc 69, which is the valve body of the check valve 105, is not axially clamped in its entirety and is not fixed to any part. The partition disc 69 contacts the spring disc 54 and contacts and separates from the bottom portion 71 of the case member 56 . The partition disk 69 is a floating type free valve whose entirety is axially movable. The partition disc 69 approaches and separates from the seat surface 61 with only the spring disc 54 acting as a non-hydraulic bias. Both the partition disk 69 and the spring disk 54 of the check valve 105 are made of metal only and do not use rubber seals. Both the partition disk 69 and the spring disk 54 are integrally formed by press working.

The biasing force of the spring disk 54 is set so that the partition disk 69 always blocks the flow of oil between the pilot chamber 101 and the variable chamber 102 regardless of the pressure states of the pilot chamber 101 and the variable chamber 102. can be In other words, the partition disk 69 should block at least one-way flow of the working fluid, including bi-directional flow between the pilot chamber 101 and the variable chamber 102 .

Since the recessed portion 64 is formed in the bottom portion 71 , the partition disc 69 can be deflected by the working fluid in the case member 56 . While blocking the communication with the variable chamber 102 , the pilot chamber 101 is deformed to expand the volume of the variable chamber 101 and decrease the volume of the variable chamber 102 by flexing so as to enter the concave portion 64 as described above. In addition, when the pressure difference between the pressure in the pilot chamber 101 and the pressure in the variable chamber 102 becomes smaller from this state, the partition disk 69 cuts off the communication between the pilot chamber 101 and the variable chamber 102 while allowing the pressure to flow into the recess 64 . The entrapment is reduced, the volume of the variable chamber 102 is increased, and the volume of the pilot chamber 101 is reduced. Further, when the pressure in the variable chamber 102 becomes higher than the pressure in the pilot chamber 101 by exceeding the biasing force of the spring disc 54 , the partitioning disc 69 is separated from the seat surface 61 against the biasing force of the spring disc 54 . The variable chamber 102 and the pilot chamber 101 are communicated with each other.

The plurality of discs 53 have the same outer diameter and have an outer diameter smaller than the minimum inner diameter of the seal member 96 of the pilot valve 52 . The plurality of discs 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 portion 76 .

The spring disk 54 includes 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 portion 112 . The substrate portion 111 has an annular shape, and the pressing plate portion 112 extends from the outer peripheral portion of the substrate portion 111 while being inclined to one side in the axial direction and radially outward. A plurality of pressure plate portions 112 are formed at intervals in the circumferential direction of the substrate portion 111 (only one portion is shown in FIG. 3 due to the cross section), and extend toward the partition disk 69 side. The plurality of pressing plate portions 112 of the spring disk 54 contact 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 against the seat surface 61 .

The disk 55 has an outer diameter smaller than the outer diameter of the base plate 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 that extends radially outward from the inner peripheral edge portion that fits onto the mounting shaft portion 28 of the piston rod 21 . A passage portion 116 in the notch 115 always communicates with the pilot chamber 101 on the one hand and the intermediate chamber 85 on the other hand. Therefore, the pilot chamber 101 always communicates with the intermediate chamber 85 through the passage portion 116 in the notch 115 . A passage portion 116 of the disk 55 is a restriction provided between the pilot chamber 101 and the intermediate chamber 85, that is, an orifice.

The disc 51 is seatable on the valve seat portion 47 of the piston 18 as described above. Disk 51 and pilot valve 352 constitute main valve 121 (first main valve). The main valve 121 is provided in the passage portion 38 in the passage hole 37 formed in the piston 18, and is generated by the sliding of the piston 18 toward the extension side (upper side in FIG. 3). (upstream chamber) to the other downstream lower chamber 20 (downstream chamber) to generate a damping force.

The main valve 121 constitutes a damping force generating mechanism 41 (first damping force generating mechanism) together with the valve seat portion 47 of the piston 18 . When the disk 51 of the main valve 121 is separated from the valve seat portion 47 and opened, the oil from the passage portion 38 is spread radially between the piston 18 and the outer cylindrical portion 373 of the case member 356 . It flows into the lower chamber 20 via the part 125 . A passage 130 (second 1 passage). Through this passage 130, when the piston 18 moves toward the upper chamber 19 side, that is, in the extension stroke, hydraulic fluid as a working fluid flows from the upper chamber 19, which is the upstream chamber, toward the lower chamber 20, which is the downstream chamber, in the cylinder 2. It becomes a passage on the extension side. The extension-side damping force generating mechanism 41, which includes the valve seat portion 47 and the main valve 121, is provided in the passage 130. generate a damping force. The damping force generating mechanism 41 is arranged on the lower chamber 20 side, which is one end side of the piston 18 in the axial direction, and attached to the piston rod 21 .

A pilot chamber 401 between the pilot valve 352 , the case member 356 and the pilot valve 52 applies internal pressure to the main valve 121 in the direction of the piston 18 , that is, in the valve closing direction in which the disk 51 is seated on the valve seat portion 47 . The opening of the main valve 121 is adjusted by the pressure in 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 whose valve opening is adjusted by the pressure in the pilot chamber 401 .

The passage portion 82 of the disk 50, the intermediate chamber 85, and the passage portion 416 of the disk 355 always communicate the passage portion 38 of the piston 18 and the pilot chamber 401, thereby introducing the oil liquid from the passage portion 38 to the pilot chamber 401. do.

Case member 356 , main valve 121 , disk 353 , disk 355 and pilot valve 52 have pilot chamber 401 communicating with upper chamber 19 via passage 38 , passage 82 , intermediate chamber 85 and passage 416 . This constitutes a valve opening control mechanism 427 that applies back pressure to the main valve 121 to control its opening.

The pilot valve 52 causes the disk 95 to be seated on the valve seat portion 374 of the 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 to generate a damping force by being seated and separated from the valve seat portion 374 . When the piston 18 moves toward the upper chamber 19 side, that is, in the extension stroke, the piston 18 moves from the upper chamber 19, which is the upstream chamber in the cylinder 2, to the pilot chamber 401 through the passage portion 38, the passage portion 82, the intermediate chamber 85, and the passage portion 416. When the disk 95 of the pilot valve 52 is separated from the valve seat portion 374 and opened, the oil flows from the pilot chamber 401 and flows between the case members 356 and 56 . The water flows into the lower chamber 20, which is the downstream chamber, through the passage portion 425 that spreads in the direction. At this time, the pilot valve 52 of the damping force generating mechanism 441 suppresses the flow of the oil to generate a damping force. The damping force generating mechanism 441 is arranged on the opposite side of the damping force generating mechanism 41 from the piston 18 and 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 formed through the passage portion 38 of the piston 18, the passage portion 82 of the disk 50, the intermediate chamber 85, and the passage portion 116 of the disk 55. , and communicates with the upper chamber 19 . The pilot chamber 101 applies 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 disk 95 is seated on the valve seat portion 374 . Damping force generating mechanism 441 includes pilot chamber 101 . The damping force generation mechanism 441 is a pressure control type damping force generation mechanism in which the opening of the pilot valve 52 is adjusted by the pressure in 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 in the pilot chamber 101 .

The case member 56 , the pilot valve 52 , the plurality of discs 53 , the spring discs 54 , the discs 55 and the partition discs 69 constitute the control mechanism section 128 . The control mechanism portion 128 has a pilot chamber 101 which is always in communication with the upper chamber 19 via the passage portion 38, the passage portion 82, the intermediate chamber 85, and the passage portion 116, and applies back pressure to the pilot valve 52, thereby It includes a valve opening control mechanism 127 that controls opening of the valve. Further, the control mechanism section 128 includes a frequency sensitive section 104 that responds to the piston frequency to vary the damping force. It includes a check valve 105 that regulates and permits oil to flow from the variable chamber 102 side, ie, the lower chamber 20 side, to the pilot chamber 101 side.

The plurality of discs 57 have the same outer diameter, which is slightly larger than the outer diameter of the valve seat portion 74 . A plurality of discs 57 constitute a disc valve 131 that can be seated on and removed from the valve seat portion 74 . By being separated from the valve seat portion 74, the disc valve 131 allows the pilot chamber 101 and the lower chamber 20 to communicate with each other through the passage portion 135 in the through hole 68, and suppresses the flow of oil therebetween. to generate the damping force. A through hole 68 is provided in the bottom portion 71 of the case member 56 so as to face the disc 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 disc 58 has a smaller outer diameter than the valve seat portion 74 , and the disc 59 has the same outer diameter as the valve seat portion 74 . The annular member 60 has an outer diameter larger than that of the disk valve 131 and a rigidity higher than that of the disk valve 131 . The disk 59 and the annular member 60 abut against the disk valve 131 when the disk valve 131 is deformed in the opening direction, thereby restricting deformation of the disk valve 131 in the opening direction beyond a prescribed limit.

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

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

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

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

As shown in FIG. 2, the compression-side damping force generating mechanism 42 includes one disc 161, one disc 162, a plurality of discs 163, and a plurality of discs in order from the piston 18 side in the axial direction. It has a disc 164 , one disc 165 , one disc 166 and one annular member 167 . The discs 161 to 166 and the annular member 167 are made of metal, and each of them has a perforated circular plate shape with a constant thickness in 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 disc 162 , and the notch 171 crosses the valve seat portion 48 in the radial direction.

The plurality of discs 163 have the same outer diameter and have the same outer diameter as the outer diameter of the disc 162 . The plurality of discs 164 have the same outer diameter, which is smaller than the outer diameter of the disc 163 . The disc 165 has an outer diameter smaller than that of the disc 164 . The disc 166 has an outer diameter larger than that of the disc 164 and smaller than that of the disc 163 . The annular member 167 has an outer diameter smaller than the outer diameter of the disk 166 and is thicker than the disks 161 to 166 and has high rigidity. This annular member 167 abuts on the shaft stepped portion 29 of the piston rod 21 .

The discs 162 to 164 constitute a disc valve 172 that can be seated on and removed from the valve seat portion 48 . By separating from the valve seat portion 48, the disc valve 172 allows the passage portion 40 in the passage hole 39 to communicate with the upper chamber 19, suppresses the flow of oil therebetween, and generates a damping force. The inner side of the notch 171 of the disc 162 forms a fixed orifice 173 that allows the upper chamber 19 and the lower chamber 20 to communicate with each other even when the disc 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 a specified limit.

In this embodiment, both the disk valve 131 on the expansion side and the disk valve 172 on the contraction side are shown as examples of disk valves of inner circumference clamping, but the present invention is not limited to this, and any mechanism that generates a damping force may be used. For example, the disk valve may be a lift type valve that is biased by a coil spring, or may be a poppet valve.

As described above, the control mechanism portion 128 including the case member 56, the pilot valve 52, the plurality of discs 53, the spring discs 54, the discs 55 and the partition discs 69 includes the valve opening control mechanism 127, the frequency sensitive portion 104 and the check valve. 105. As shown in FIG. 3 , the frequency sensitive section 104 has a partition disk 69 that is deformable within the recess 64 , and the deformation within the recess 64 changes the capacity of the pilot chamber 101 . The partition disc 69 deforms according to the frequency of reciprocating motion of the piston 18 to change the capacity of the pilot chamber 101 always communicating with the upper chamber 19 and the capacity of the variable chamber 102 always communicating with the lower chamber 20 .

As shown in FIG. 2, the mounting shaft portion 28 is inserted through the piston rod 21, and the shaft stepped portion 29 is provided with an annular member 167, a disc 166, a disc 165, a plurality of discs 164, a plurality of discs 164, and a plurality of discs 164. 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, A case member 56, a plurality of discs 57, a disc 58, a disc 59, and an annular member 60 are stacked in this order. At that time, as shown in FIG. 3, the partition disc 69 is arranged between the bottom portion 71 of the case member 56 and the spring disc 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 , a nut 185 is screwed onto the male thread 31 of the mounting shaft portion 28 projecting from the annular member 60 with the parts thus arranged. As a result, the parts from the annular member 167 to the annular member 60 stacked as described above are clamped in the axial direction by being sandwiched between the axial stepped portion 29 of the piston rod 21 and the nut 185 on the inner peripheral side or all of them. ing. At that time, the partition disk 69 is sandwiched between the spring disk 54 and the case member 56 without being axially clamped.

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 on the lower side of the base valve member 191 , that is, on the reservoir chamber 6 side, and an upper side of the base valve member 191 , that is, on the lower side. It has a disc 193 provided on the chamber 20 side and mounting pins 194 for mounting the discs 192 and 193 to 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 for circulating the oil between the lower chamber 20 and the reservoir chamber 6 , and a plurality of passage holes 195 , which are radially outside the base valve member 191 from the passage holes 195 . A plurality of passage holes 196 are formed between the reservoir 20 and the reservoir chamber 6 for circulating the oil. The disk 192 on the reservoir chamber 6 side allows the oil to flow from the lower chamber 20 to the reservoir chamber 6 through the passage hole 195, while allowing the oil to flow from the reservoir chamber 6 to the lower chamber 20 through the passage hole 195. suppress The disk 193 allows the oil to flow from the reservoir chamber 6 to the lower chamber 20 through the passage hole 196 , while inhibiting the oil from flowing 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 compression-side damping valve mechanism 197 that opens during the compression stroke of the shock absorber 1 to flow oil from the lower chamber 20 to the reservoir chamber 6 and generate damping force. ing. The disk 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 allow oil to flow from the reservoir chamber 6 into the lower chamber 20 . The suction valve mechanism 198 supplies oil 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 oil caused mainly by the extension of the piston rod 21 from the cylinder 2. fulfill the function of flushing.

FIG. 4 is a hydraulic circuit diagram of the shock absorber 1 of the first embodiment described above. Specifically, the upper chamber 19 and the intermediate chamber 85 communicate with each other through the passage portion 82, the pilot chamber 401 and the intermediate chamber 85 communicate with each other through the passage portion 416, and the pilot chamber 101 and the intermediate chamber 85 communicate with each other through the passage portion 116. communicated through The upper chamber 19 and the lower chamber 20 can communicate with each other via a damping force generating mechanism 41 and a damping force generating mechanism 42 . Pilot chamber 401 can communicate with lower chamber 20 via damping force generating mechanism 441 , and pilot chamber 101 can communicate with lower chamber 20 via damping force generating mechanism 145 . The pressure in the pilot chamber 401 controls opening of the damping force generating mechanism 41 , and the pressure in the pilot chamber 101 controls opening of the damping force generating mechanism 441 . Pilot chamber 101 can communicate with variable chamber 102 via check valve 105 , and variable chamber 102 communicates with lower chamber 20 . Here, passage portion 82, passage portion 416, and passage portion 116, which are all orifices communicating with intermediate chamber 85, have a passage area larger than that of passage portion 116. Also, the passage portion 416 is 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 flows toward the lower chamber 20 through the passage portion 38 of . The flow of oil from the upper chamber 19 through the passage portion 38 during the extension stroke is damped through the passage portion 38 shown in FIG. There is a flow path through the force generating mechanism 41 and through the passage 125 between the piston 18 and the case member 356 to the lower chamber 20 . This flow is through passageway 130 .

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

Furthermore, in the extension stroke, the hydraulic oil flows from the upper chamber 19 through the passage 38, flows from the passage 38 through the passage 82 in the disk 50, and passes through the intermediate chamber 85 in parallel with the above. , through the passage portion 116 of the disk 55 to the pilot chamber 101, which is the 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 disk valve. There is a flow path through the damping force generating mechanism 145 including 131 to the lower chamber 20 . This flow is through passageway 140 .

When a low frequency input (large amplitude input) is applied to the buffer 1, the amount of oil flowing from the upper chamber 19 to the pilot chamber 101 via the passage portion 38, the passage portion 82, the intermediate chamber 85 and the passage portion 116 is As a result, the partition disc 69 of the frequency sensitive portion 104 is deformed until it comes into surface contact with the stopper surface 63 of the recess 64 on the side of the case member 56 and the deflection is restricted. If the deflection of the partition disk 69 is restricted by the stopper surface 63 in this way, the volume of the pilot chamber 101 cannot be expanded. , the opening pressure of the pilot valve 52 increases. Since the pressure in the pilot chamber 401 also rises until the pilot valve 52 opens, the opening pressure of the main valve 121 of the damping force generating mechanism 41 also rises. Therefore, as indicated by the solid line X1 in FIG. 5, the damping force has a hard characteristic.

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

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

When the piston speed is further increased, at a predetermined piston speed v2 indicated by the solid line X1 shown in FIG. In addition, the damping force generating mechanism 41 is opened to flow into the lower chamber 20 through the passage portion 125 between the piston 18 and the case member 356 . Therefore, the rate of increase in damping force is further reduced with respect to the increase in piston speed (see piston speed v2 and thereafter in FIG. 5).

When a high-frequency input (small-amplitude input) is applied to the buffer 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 amount of deflection of the partition disk 69 of the sensitive part 104 also decreases, and the partition disk 69 deforms within a range that does not contact the stopper surface 63 of the recess 64 on the case member 56 side. Therefore, since the amount of oil flowing into the pilot chamber 101 can be absorbed by the deflection of the partition disc 69, the pressure in the pilot chamber 101 does not rise and becomes low. is low. Further, by opening the pilot valve 52 from a low pressure in this way, the pressure in the pilot chamber 401 does not increase and becomes low, so the valve opening pressure of the main valve 121 of the damping force generating mechanism 41 is also low. Therefore, as indicated by the solid line X2 in FIG. 5, the damping force has softer characteristics than when the low-frequency input is indicated by the solid line X1.

At the time of this high-frequency input, as well as at the low-frequency input, in the very low speed range where the piston speed is very low, the hydraulic fluid that has entered the passage portion 38 from the upper chamber 19 is in the valve closing state of the damping force generating mechanism 41. It flows only through the fixed orifice 92 of the main valve 121 and into the lower chamber 20 only through the passage portion 125 between the piston 18 and the case member 356 . Therefore, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the increase rate of the damping force becomes relatively high with respect to the increase of the piston speed (see piston speed 0 to v3 in FIG. 5).

From this state, when the piston speed is increased to increase the flow rate through the passage portion 38 of the piston 18, at a predetermined piston speed v3 indicated by the 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 , opens the pilot valve 52 of the damping force generating mechanism 441 from the pilot chamber 401 , and flows between the case members 356 and 56 . flows into the lower chamber 20 through the passage portion 425 of . Therefore, the characteristic of the damping force with respect to the piston speed becomes the valve characteristic, and the increase rate of the damping force becomes relatively low with respect to the increase of the piston speed (see piston speed v3 to v4 in FIG. 5).

When the piston speed is further increased, at a predetermined piston speed v4 indicated by the solid line X2 shown in FIG. In addition, the main valve 121 of the damping force generating mechanism 41 is opened to flow into the lower chamber 20 through the passage portion 125 between the piston 18 and the case member 356 . Therefore, the rate of increase in damping force is further reduced with respect to the increase in piston speed (see piston speed v4 and thereafter in FIG. 5).

According to the shock absorber 1 described above, when a low frequency input with a hard damping force characteristic is input, the valve opening point increases as indicated by the solid line X1 in FIG. Compared to shock absorbers with a small number of valve points, it is possible to mitigate sudden changes in transient valve opening characteristics when the valve is opened. Even at the time of high-frequency input with soft damping force characteristics, the valve opening point increases as indicated by the solid line X2 in FIG. It is possible to mitigate sudden changes in transient valve opening characteristics when the valve is opened. Here, when the transient force change at the time of valve opening is transmitted to the vehicle body, it causes ride comfort and abnormal noise heard inside the vehicle. It is possible to prevent the generation of abnormal noise.

Even if the two damping force generating mechanisms 441, 41 perform two-stage pressure control, there is no qualitative change in the frequency characteristics. A hard damping force characteristic is obtained at low frequency input, and a soft damping force characteristic is switched at high frequency input. The cut-off frequency varies depending on the total pressure loss at two points in series, ie, passage 116 and passage 82, and thus depends on the flow area of passages 116 and 82. FIG. Therefore, the cutoff frequency can be easily tuned by adjusting the flow area of the passages 116 and 82 .

In the compression stroke in which the piston rod 21 moves toward the compression side, when the piston speed is slow, the oil from the lower chamber 20 flows through the passage portion 40 in the passage hole 39 on the compression side and the damping force generating mechanism 42 shown in FIG. A damping force having a flow orifice characteristic is generated in the upper chamber 19 via the fixed orifice 173 of the disk valve 172 of . Therefore, the characteristic of the damping force with respect to the piston speed is such that the rate of increase in the damping force is relatively high with respect to the increase in piston speed (see piston speed 0 to v5 in FIG. 5).

Further, when the piston speed increases, the oil introduced from the lower chamber 20 into the passage portion 40 in the passage hole 39 on the compression side basically opens the disc valve 172 of the damping force generating mechanism 42 and It flows into the upper chamber 19 through the gap between the valve seat portion 48 and a damping force of valve characteristics is generated. For this reason, the characteristic of the damping force with respect to the piston speed is such that the rate of increase in the damping force decreases as the piston speed increases (see piston speed v5 and thereafter in FIG. 5).

Here, in the frequency sensitive part 104 , the pressure in the lower chamber 20 becomes higher during the contraction stroke, 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 element 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 oil flows from the lower chamber 20 toward the upper chamber 19 through the passage 140 . At this time, the partition disk 69 is separated from the disk contact portion 62, so that the differential pressure disappears and further movement is suppressed.

The aforementioned Patent Document 1 describes a shock absorber whose damping force is variable in response to frequency. By the way, in the shock absorber, for example, if the damping force characteristic is changed significantly, there is a possibility that the ride comfort is deteriorated or abnormal noise is generated. Therefore, dampers are required to have smooth damping force characteristics.

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

Also, the pilot chamber 101 of the second damping force generating mechanism 441 is composed of 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 disc 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 sensitive section 104, the number of parts can be reduced. Therefore, the cost and weight can be reduced.

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

In the second embodiment, a passage groove 490 separate 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 thread 31, as shown in FIG. A passage portion 491 is formed inside the passage groove 490 .

Further, in the second embodiment, instead of the damping force generating mechanism 441 of the first embodiment, a damping force generating mechanism 41A (second damping force generating mechanism) substantially similar to the damping force generating mechanism 41 is provided. . Here, in order to distinguish each configuration of the damping force generation mechanism 41A from each configuration of the damping force generation mechanism 41, the corresponding configuration of the damping force generation mechanism 41 will be described with "A" attached.

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 which is the same part as the disk 355, a case member 356A (case) which is the same part as the case member 356, and the disk 500.

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

The disc 50A has an outer diameter smaller than the inner diameter of the valve seat portion 374 of the case member 356 . The notch 81 of the disc 50 is not formed in the disc 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. As shown in FIG. The disk 51A is in contact with the valve seat portion 374, and opens and closes the pilot chamber 401 of the case member 356 by separating and contacting the valve seat portion 374. As shown in FIG. The notch 91A of the disk 51A crosses the valve seat portion 374 in the radial direction. Therefore, the inner side of the notch 91A serves as a fixed orifice 92A that always communicates the pilot chamber 401 with the lower chamber 20 via the passage portion 425. As shown in FIG.

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

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

As shown in FIG. 6, the main valve 121A consisting of the disk 51A and the pilot valve 352A constitutes the damping force generating mechanism 41A together with the valve seat portion 374 of the case member 356. As shown in FIG. When the disk 51A of the main valve 121A is separated from the valve seat portion 374 and opened, the oil in the pilot chamber 401 flows downward through the radially expanding passage portion 425 between the case members 356 and 356A. Flow to chamber 20.

The pilot chamber 401A between the main valve 121A, the case member 356A, the disc valve 131 and the disc 500 is closed by allowing the main valve 121A to sit in the direction of the case member 356, that is, the disc 51A is seated on the valve seat portion 374. Apply internal pressure in the direction. The opening of the main valve 121A is adjusted by the pressure in 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 in the pilot chamber 401A.

The disc valve 131 leaves the valve seat portion 374A when the pressure in the pilot chamber 401A reaches a predetermined pressure. The disc valve 131, together with the valve seat portion 374A, constitutes a damping force generating mechanism 145, which is a hard valve that opens to generate a damping force when the pressure in the pilot chamber 401A reaches a predetermined pressure. A plurality of discs on the case member 356A side of the disc valve 131 can be seated on the valve seat portion 374A.

On the mounting shaft portion 28 of the piston rod 21, on the side opposite to the case member 356A of the disc valve 131, a disc 511 having a smaller diameter than the smallest disc of the disc valve 131 and a disc 512 having a larger diameter than the disc 511 are provided. A frequency sensitive portion 530 is provided adjacent to the disk 512 on the opposite side of the disk 512 to change the damping force in response to the piston frequency.

As shown in FIG. 7, the frequency sensitive part 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 . It also has one partition disk 534 (disk), one disk 535 , one disk 536 and one lid member 539 . Case member 531, discs 533, 535, 536 and lid member 539 are made of metal. Each of the discs 533, 535, 536 has a perforated circular flat plate shape with a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted. The case member 531 and the lid member 539 have an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted. The case member 531 and a cover member 539 constitute a box-shaped frequency sensitive unit case 540 . The mounting shaft portion 28 of the piston rod 21 is partially arranged inside the case member 531 .

The case member 531 has a bottomed tubular shape having a perforated disk-shaped bottom portion 541 and a cylindrical tubular portion 544 protruding 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 disc-shaped bottom portion main portion 547, an annular projecting portion 542 projecting from the inner peripheral side of the bottom portion main portion 547 toward the cylinder portion 544 side in the axial direction from the bottom portion main portion 547, and a bottom portion. An annular support portion 543 protrudes from between the projecting portion 542 and the cylindrical portion 544 of the main body portion 547 toward the cylindrical portion 544 side in the axial direction from the bottom main body portion 547 . In other words, the bottom portion 541 has a protruding portion 542 that protrudes on the inner peripheral side of the bottom main body portion 547 on the same side as the cylindrical portion 544 and is located on the same side as the cylindrical portion 544 on the same side as the bottom main body portion 547 on the intermediate position in the radial direction. A protruding support portion 543 is formed respectively.

A channel groove 548 is partially formed in the circumferential direction in the projecting portion 542 so as to traverse the projecting portion 542 in the radial direction. A channel groove 503 is partially formed in the support portion 543 in the circumferential direction so as to traverse the support portion 543 in the radial direction. A small-diameter hole 545 into which the mounting shaft portion 28 of the piston rod 21 is fitted is formed on the inner peripheral side of the bottom portion 541 on the side opposite to the axial protrusion 542 . A large-diameter hole portion 546 having a larger diameter than the small-diameter hole portion 545 is formed. The channel groove 548 opens into the large-diameter hole portion 546 . An opening 549 is formed on the opposite side of the cylindrical portion 544 from the bottom portion 541 . Accordingly, the case member 531 is composed of a cylindrical portion 544 having an opening 549 at one end, and a bottom portion 541 extending radially inward from the side of the cylindrical portion 544 opposite to the opening 549 . The cylindrical portion 544 has a tapered inner peripheral surface 550 whose inner diameter increases from the bottom portion 541 toward the opening portion 549 . The lid member 539 is provided on the opening 549 side of the cylindrical portion 544 of the cylindrical case member 531 and configures the frequency sensitive portion case 540 together with the case member 531 .

The mounting shaft portion 28 passes through the radial center of the case member 531 in the axial direction. It is arranged so that it penetrates inside the

The bottom 541 of the case member 531 supports the inner peripheral side of the disk 512 at its 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 protruding portion 542 supports the outer peripheral side of the disk 533 . The supporting portion 543 of the case member 531 supports the intermediate position in the radial direction of the annular partition disk 534 at the end on the projecting tip side. The support portion 543 always communicates between the radially inner side and the radially outer side of the support portion 543 of the case member 531 by means of the channel groove 503 .

The plurality of discs 533 have an outer diameter smaller than the outer diameter of the projecting portion 542 of the case member 531 . A channel groove 548 radially traverses the projection 542 .

The partition disk 534 is composed of a perforated circular plate-like flexible disk 555 made of a metal material of a certain thickness and an elastic seal member 556 made of a rubber material and fixed to the outer peripheral side of the disk 555 . Compartment disk 534 is generally circular and is elastically deformable or flexable. The annular disk 555 has an inner diameter larger than the outer diameter of the disk 533, and has an inner diameter that allows the disk 533 to be arranged inside with a gap in the radial direction. The disk 555 is thinner than the thickness of the disk 533 (two sheets). The disc 555 has an inner diameter smaller than the outer diameter of the disc 535 and can abut against the disc 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 tubular portion 544 . The disk 555 is arranged inside the case member 531 with the mounting shaft portion 28 penetrating therethrough. The disk 555 is provided on the bottom portion 541 within the case member 531 . The cylindrical portion 544 of the case member 531 has a tapered shape in which the inner diameter increases with increasing distance from the bottom portion 541 toward the partition disk 534 .

The sealing member 556 is fixed to the outer peripheral side of the disc 555 in an annular shape. The sealing member 556 is fixed to the disk 555 over the entire circumference of the surface facing the disk 555 . The seal member 556 has a seal portion 558 protruding from the disc 555 in the axial direction opposite to the lid member 539 , and a stopper portion 559 protruding from the disc 555 in the axial direction toward the lid member 539 . The seal portion 558 has a cylindrical shape and is slidably and liquid-tightly fitted over the entire circumference of the inner peripheral surface of the cylindrical portion 544 of the case member 531 . is always sealed.

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

The partition disk 534 is centered with respect to the case member 531 by the sealing portion 558 contacting the tubular portion 544 of the case member 531 over the entire circumference. The partition disk 534 is supported by the disk 555 contacting the support portion 543 of the case member 531 .

The projecting portion 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 inner peripheral side of the disc 555 of the partition disc 534 is arranged between the projecting portion 542 of the case member 531 and the disc 535, and is movable within the range between them. The partition disk 534 is supported by the disk 555 in contact with the support portion 543 and the disk 535 when there is no pressure difference between the front side and the rear side of the partition disk 534 . The disk 535 is a seat portion on which the partition disk 534 is seated.

The inner peripheral side of the disc 555 of the partition disc 534 is movable between the projecting portion 542 of the case member 531 and the disc 535 within the range of the axial length of the plurality of discs 533 . Also, the partition disk 534 is provided with an annular seal portion 558 for sealing between the disk 555 and the case member 531 on the outer peripheral side, which is the non-supported side opposite to the support by the disk 535 . The partition disk 534 has a simple support structure in which the inner peripheral side thereof is supported by the disk 535 only on one side without being clamped from both sides. The disk 536 has an outer diameter larger than that of the disk 535 .

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

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

Here, the lid member 539 has a mirror-symmetrical shape with reference to a plane that passes through the center position in the axial direction and is perpendicular to the axial direction. In other words, the lid member 539 has a shape that does not distinguish between the front and back and does not cause erroneous assembly due to a mistake in the front and back. Lid member 539 can be formed by sintering.

The seal portion 558 of the partition disk 534 is in contact with the inner peripheral surface 550 of the tubular portion 544 of the case member 531 over the entire circumference to seal the gap between the partition disk 534 and the tubular portion 544 . That is, the compartment disc 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 the frequency sensitive portion case 540 within the allowable range. The division disk 534 is centered by being fitted into the frequency sensitive part case 540, and in this state, the inner circumference of the disk 555 is brought into contact with the disk 535 over the entire circumference, thereby closing the gap between the disk 535 and the disk 535. to seal.

The partition disk 534 partitions the inside of the frequency sensitive part case 540 into two chambers, a case chamber 571 (housing inner chamber) with variable capacity on the bottom 541 side and a case chamber 572 with variable capacity 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 defined by the partition disc 534 . Case chamber 571 is formed between partition disk 534 and bottom portion 541 of case member 531 .

In the second embodiment, the passage portion 82 of the disc 50, the intermediate chamber 85, the passage portion 416A of the disc 355A, the pilot chamber 401A, the passage portion 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 channel groove 548 of the case member 531 , the case chambers 571 and 572 constitute the parallel passage 141 of the passage 140 . ing. Therefore, the case member 531, which is a housing having the case chambers 571 and 572 inside, is formed with at least a part of a passage 140 connecting the upper chamber 19 and the lower chamber 20 by a route different from that of the passage 130. there is

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

The frequency sensitive part 530 has its frequency sensitive part case 540 provided in the parallel passage 141 of the passage 140 . Accordingly, the frequency sensitive part case 540 is provided with two case chambers 571 and 572 which are part of the parallel passage 141 and are defined by the partition disc 534 therein. The 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 is tapered such that the inner diameter is larger on the opening 549 side than on the bottom portion 541. is. Therefore, the cylindrical portion 544 of the case member 531 has a tapered inner peripheral surface 550 in which the inner diameter increases with distance from the bottom portion 541 toward the partition disk 534 in the axial direction.

The partition disk 534 can be displaced and deformed within a range where the inner peripheral side moves between the projecting portion 542 of the case member 531 and the disk 535 and the outer peripheral side moves between the support portion 543 and the flange portion 562 of the lid member 539 . It's becoming Here, the axially shortest distance between the supporting portion 543 that supports the axially intermediate portion of the disc 555 of the partitioning disc 534 from one side in the axial direction and the disc 535 that supports the inner peripheral side of the disc 555 from the other side in the axial direction The distance is less than the axial thickness of disk 555 . Therefore, when the pressure in the case chambers 571 and 572 is the same, the disk 555 is slightly deformed and pressed against the supporting portion 543 and the disk 535 by its own elastic force.

Partition disk 534 blocks the flow of oil between case chambers 571 and 572 of parallel passage 141 when the inner peripheral side of disk 555 is in contact with disk 535 over the entire circumference. In addition, the partition disk 534 permits oil to flow between the case chambers 571 and 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 disc 534 and the disc 535 as its seat portion restrict the flow of oil 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 is configured to allow oil to flow from 572 to case chamber 571 .

The check valve 591 communicates with the parallel passage 141 that allows communication between the upper chamber 19 and the lower chamber 20 via the passage portion 38 of the piston 18 during the extension stroke when the pressure on the upper chamber 19 side becomes higher than the pressure on the lower chamber 20 side. is cut off, while in the compression stroke in which the pressure on the upper chamber 19 side becomes lower than the pressure on the lower chamber 20 side, the parallel passage 141 is brought into communication. The check valve 591 is a free valve in which the entire partition disk 534, which is the valve element thereof, is movable in the axial direction. The partition disk 534 is provided movably with respect to the case member 531 and forms a case chamber 571 between itself and the bottom portion 541 of the case member 531 . The pilot chamber 401A is composed of a case member 356A separate from the case member 531 and the main valve 121A.

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

Further, in parallel with the flow of the oil from the upper chamber 19 through the passage portion 38 in the extension stroke, the oil flows from the passage portion 38 through the passage portion 82 in the disk 50, and flows through the intermediate chamber 85 and the disk. 355 to the pilot chamber 401, which is the back pressure chamber of the main valve 121, and through the pilot chamber 401, the valve seat portion 374 of the case member 356 and the damping force generating mechanism 41A including the main valve 121A. Thus, there is a flow path to the lower chamber 20 through the passage portion 425 between the case member 356 and the case member 356A. Here, too, the intermediate chamber 85 and the pilot chamber 401 have the same pressure because the passage portion 416 serving as a throttle therebetween is sufficiently wide.

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

At the time of low frequency input (large amplitude input) to the buffer 1, from the upper chamber 19, passage 38, passage 82, intermediate chamber 85, passage 416A, pilot chamber 401A, passage 502, passage 491, passage A large amount of oil flows through the portion 582 and the passage portion 581 into the case chamber 571 of the frequency sensitive portion 530 , and the deflection amount of the partition disc 534 also increases. It abuts against 562 and deforms until the deflection is restricted. If the deflection of the partition disk 534 is restricted by the cover member 539 in this way, the volume of the case chamber 571 cannot be expanded, and thereafter the pressure in the pilot chamber 401A rises to a high pressure and the damping force generating mechanism 41A. , the opening pressure of the main valve 121A increases. Since the pressure in the pilot chamber 401 also increases until the main valve 121A opens, the opening pressure of the main valve 121 of the damping force generating mechanism 41 also increases. Therefore, the damping force becomes a hard characteristic.

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

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

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

At the time of high frequency input (small amplitude input) to the buffer 1, from the upper chamber 19, the passage 38, the passage 82, the intermediate chamber 85, the passage 416A, the pilot chamber 401A, the passage 502, the passage 491, the passage The amount of oil flowing through 582 and passage portion 581 to case chamber 571 of frequency sensitive portion 530 is small, and the amount of deflection of partition disc 534 is also small. Transform in range. Therefore, since the amount of oil flowing into the case chamber 571 can be absorbed by the deflection of the partition disc 534, the pressure in the pilot chamber 401A, which is always in communication with the case chamber 571, does not rise and becomes low, so that the damping force generating mechanism 41A is mainly operated. 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 rise and becomes low, so 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, similarly to the low-frequency input, in the very low speed range where the piston speed is very low, the hydraulic fluid that has entered the passage portion 38 from the upper chamber 19 is in the closed state of the damping force generating mechanism 41. It flows through the fixed orifice 92 of the main valve 121 and into the lower chamber 20 via the passage portion 125 between the piston 18 and the case member 356 . Further, the oil liquid that has entered the passage portion 38 flows from the passage portion 82, the intermediate chamber 85, the passage portion 416, and the pilot chamber 401 through the fixed orifice 92A of the main valve 121A in the closed state of the damping force generating mechanism 41A. , flows into the lower chamber 20 through the passage portion 425 between the case member 356 and the case member 356A. Therefore, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the increase rate of the damping force becomes relatively high with respect to the increase of the piston speed.

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

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

Here, in the frequency sensitive part 530 , the pressure in the lower chamber 20 is increased during the contraction stroke, and the pressure in the case chamber 572 is higher than the pressure in the case chamber 571 . As a result, the partition disk 534 as the valve body of the check valve 591 is deformed with the supporting portion 543 of the case member 356 as a fulcrum and is separated from the disk 535 as the valve seat of the check valve 591 . As a result, the check valve 591 opens the passage 140 and oil flows from the lower chamber 20 to the upper chamber 19 through the passage 140 . At that time, the partition disk 534 is separated from the disk 535 so that the differential pressure disappears and further movement is suppressed.

The shock absorber 1 of the second embodiment includes a main valve 121 which is provided in the passage 130 and suppresses the flow of oil from the upper chamber 19 to the lower chamber 20 by sliding of the piston 18 to generate a damping force. 121 has a first damping force generating mechanism 41 having a pilot chamber 401 that applies pressure in the valve closing direction. A bottomed cylindrical case member 531 in which at least part of the passage 140 parallel to the passage 130 is formed, and a bottom portion 541 of the case member 531 which is provided movably with respect to the case member 531. and a compartment disc 534 forming a case chamber 571 therebetween. By forming the case chamber 571 with the case member 531 and the partition disk 534, the damping force can be varied in response to the frequency. In addition to the first damping force generating mechanism 41, the main valve 121A suppresses the flow of oil from the pilot chamber 401 to the lower chamber 20 to generate a damping force, and the main valve 121A is pressurized in the closing direction. and a second damping force generating mechanism 41A having a pilot chamber 401A to act on. As a result, the damping force can be switched in a plurality of stages in response to an increase in piston speed. Therefore, it is possible to smooth the damping force characteristics. As a result, it is possible to suppress deterioration in ride comfort and generation of abnormal noise.

Further, since the pilot chamber 401A is composed of the case member 356A separate from the case member 531 of the frequency sensitive portion 530 and the main valve 121A, the frequency sensitive portion 530 can be easily assembled to the piston rod 21. can be done.

In addition, 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 side increases, friction when the seal portion 558 of the partition disk 534 slides can be reduced. can.

That is, the seal portion 558 of the partition disk 534 is provided on the disk 555 so as to face the bottom portion 541 side opposite to the lift direction of the partition disk 534 when the pressure in the case chamber 571 is increased. Therefore, if the cylindrical portion 544 has a straight inner diameter, as the dividing disk 534 lifts away from the bottom portion 541 due to the pressure increase in the case chamber 571, the pressure in the case chamber 571 pushes the cylindrical portion of the sealing portion 558. The interference with respect to 544 increases, and the sliding friction of the seal portion 558 with respect to the cylindrical portion 544 increases. On the other hand, by tapering the cylindrical portion 544 so that the inner diameter of the cylindrical portion 544 expands in the lifting direction of the partition disk 534, it is possible to prevent the sealing portion 558 from becoming excessively tight against the cylindrical portion 544 during lifting. can be prevented and excessive friction can be prevented.

FIG. 8 shows the analysis results of the characteristics of the compression force applied to the cylindrical portion 544 of the second embodiment from the seal portion 558 with respect to the pressure load. As indicated by the dashed line Y1 in FIG. 8, when the pressure load on the partition disc 534 received from the case chamber 571 increases, the tension force (that is, friction) on the cylindrical portion 544 received from the seal portion 558 increases. Compared to the case where the inner diameter of the tubular portion 544 indicated by the solid line Y2 in FIG.

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

Further, by tapering the tubular portion 544 of the case member 531 so that the inner diameter of the tubular portion 544 expands in the direction of the partition disk 534, the ease of assembly can be improved. That is, by forming the cylindrical portion 544 of the case member 531 into a tapered shape with a larger diameter on the opening 549 side, it becomes easier to fit the dividing disk 534 into the cylindrical portion 544 from the opening 549 side. At this time, by setting the inner diameter of the opening 549 larger than the outer diameter of the partition disk 534, the sealing portion 558 is less likely to be caught in the opening 549 of the cylindrical portion 544 when the partition disk 534 is incorporated into the case member 531. It becomes easy to fit, and can improve assembleability.

[Third Embodiment]
Next, the third embodiment will be described mainly based on FIG. 9, focusing on the differences from the second embodiment. Parts common to those of the second embodiment are denoted by the same designations and the same reference numerals.

In the third embodiment, the main valve 121 of the damping force generating mechanism 41 has multiple discs 601 between the disc 51 and the pilot valve 352 . Also, the damping force generating mechanism 41 does not have the disk 355 of the second embodiment. Further, the disc 50A, the disc 51A, the pilot valve 352A, the disc 353A, the disc 355A and the case member 356A of the damping force generating mechanism 41A of the second embodiment are not provided. A large-diameter hole portion 376 of the case member 356 is formed on the opposite side of the disk 353 in the axial direction, and a small-diameter hole portion 375 is formed on the disk 353 side in the axial direction. Disk 500 abuts on case member 356 and disk valve 131 , and passage portion 502 in notch 501 is intermediate chamber 85 including large diameter hole portion 376 in case member 356 and pilot chamber 401 . and are in constant communication with each other. A passage portion 502 of the disc 500 serves as a restriction, or orifice, provided between the intermediate chamber 85 and the pilot chamber 401 .

A disk 511, a disk 512 and a frequency sensitive portion 530 similar to those in the second embodiment are provided on the opposite side of the disk valve 131 to the disk 500. FIG. In the third embodiment, the frequency sensitive portion 530 has the large diameter hole portion 546 of the case member 531 directly communicating with the passage groove 30 of the piston rod 21 , so that the case chamber 571 always communicates with the intermediate chamber 85 . ing.

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

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

When a low frequency input (large amplitude input) is applied to the buffer 1, the oil flows from the upper chamber 19 to the case chamber 571 through the passage portion 38, the passage portion 82, the intermediate chamber 85, and the passage portion 581 of the frequency sensitive portion 530. As the amount of liquid increases, the amount of deflection of the partition disk 534 also increases, and the partition disk 534 contacts the flange portion 562 of the lid member 539 with the stopper portion 559 and deforms until the deflection is restricted. In this state in which the deflection of the partition disk 534 is restricted by the lid member 539, the oil from the upper chamber 19 enters the pilot chamber 401 through the passage portion 38, the passage portion 82, the intermediate chamber 85 and the passage portion 502. flow in. Then, the pressure in the pilot chamber 401 rises to a high pressure, and the opening pressure of the main valve 121 of the damping force generating mechanism 41 rises. Therefore, the damping force becomes a hard characteristic.

At the time of this low-frequency input, in a very low speed region where the piston speed is very low, the oil that has entered the passage portion 38 from the upper chamber 19 flows through the fixed orifice of the main valve 121 in which the damping force generating mechanism 41 is closed. 92 and into the lower chamber 20 via the passage portion 125 between the piston 18 and the case member 356 . Therefore, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the increase rate of the damping force becomes relatively high with respect to the increase of the piston speed.

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

When a high frequency input (small amplitude input) is applied to the buffer 1, the amount of oil flowing from the upper chamber 19 to the case chamber 571 via the passage portion 38, the passage portion 82, the intermediate chamber 85 and the passage portion 581 is small. The amount of deflection of the disk 534 is also reduced, and the deformation is within a range in which the deflection is not restricted even when the stopper portion 559 abuts against the lid member 539 . Therefore, since the amount of oil flowing into the case chamber 571 can be absorbed by the deflection of the partition disc 534, the pressure in the pilot chamber 401, which is always in communication with the case chamber 571, does not rise and becomes low. The opening pressure of the valve 121 is low. Therefore, the damping force has a soft characteristic.

At the time of this high-frequency input, similarly to the low-frequency input, in the very low speed range where the piston speed is very low, the hydraulic fluid that has entered the passage portion 38 from the upper chamber 19 is in the closed state of the damping force generating mechanism 41. It flows through the fixed orifice 92 of the main valve 121 and into the lower chamber 20 via the passage portion 125 between the piston 18 and the case member 356 . Therefore, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and the increase rate of the damping force becomes relatively high with respect to the increase of the piston speed.

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

According to the shock absorber 1 of the third embodiment, similarly to 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 toward the partition disk 534 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 with respect to the cylindrical portion 544 without being caught, the damping force characteristic can be made smooth. As a result, it is possible to suppress deterioration 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 expands in the direction of the partition disk 534, it becomes easier to fit the partition disk 534 into the cylindrical portion 544, thereby improving the ease of assembly. can.

In the above embodiment, an example in which the present invention is applied to a double-tube hydraulic shock absorber is shown. However, the present invention is not limited to this. It may be used for a monotube hydraulic shock absorber that forms a gas chamber with a movable partition, and can be used for any shock absorber including a pressure control valve that uses a packing valve with a seal member provided on a disc. can. Of course, it is also possible to apply the present invention to the damping force generating mechanism 42 on the contraction side or to the base valve 25 described above. Further, the present invention can also be applied to the 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. Moreover, in the above embodiment, the hydraulic shock absorber is shown as an example, but water or air can also be used as the fluid.

A first aspect of the above-described embodiment includes a cylinder in which a working fluid is enclosed, a piston slidably provided inside the cylinder and defining two chambers in the cylinder, and a one end portion. a piston rod fixed to the piston inside the cylinder and having the other end protruding outside the cylinder via a rod guide; A passage, 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, and at least part of the second passage formed therein. and a disc that is movably provided with respect to the housing and forms a housing inner chamber between the housing bottom and the first damping force generating mechanism. a first main valve that suppresses the flow of the working fluid from the upstream chamber to the downstream chamber by sliding of the piston to generate a damping force; and a first pilot that applies pressure to the first main valve in a closing direction. and a second damping force generating mechanism for suppressing the flow of working fluid from the first pilot chamber to the downstream chamber to generate a damping force, wherein the second damping force generating mechanism comprises the a second main valve that suppresses the flow of 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. I have. This makes it possible to smooth the damping force characteristics.

According to a second aspect, in the first aspect, the second pilot chamber is composed of the housing, the disc, and the second main valve. Thereby, the number of parts can be reduced, and the cost can be reduced.

According to a third aspect, in the first aspect, the second pilot chamber is composed of a case separate from the housing and the second main valve. This makes it possible to facilitate assembly.

According to a fourth aspect, in any one of the first to third aspects, the tubular portion of the housing has a tapered shape in which the inner diameter increases with increasing distance from the bottom toward the disk. As a result, the disk moves smoothly with respect to the cylindrical portion of the housing, and damping force characteristics can be smoothed.

A fifth aspect comprises a cylinder in which a working fluid is sealed, a piston slidably provided inside the cylinder and defining two chambers in the cylinder, and a portion of one end side of the piston inside the cylinder. a piston rod having the other end portion projecting outside the cylinder via a rod guide; a first passage through which a working fluid flows out from one chamber in the cylinder due to the movement of the piston; a second passage provided in parallel with the second passage, a damping force generating mechanism provided in the first passage to generate a damping force, and a bottomed cylindrical housing in which at least part of the second passage is formed and a disk movably provided with respect to the housing and forming a housing inner chamber between itself and the bottom of the housing, wherein the damping force generating mechanism moves from the upstream chamber to the downstream chamber by sliding of the piston. A main valve that suppresses the flow of working fluid to the chamber to generate a damping force, and a pilot chamber that applies pressure to the main valve in a valve closing direction. It has a tapered shape in which the inner diameter increases toward the side. As a result, the disk moves smoothly with respect to the cylindrical portion of the housing, and damping force characteristics can be smoothed.

1 shock absorber 2 cylinder 18 piston 19 upper chamber (upstream chamber)
20 lower chamber (downstream chamber)
21 piston rod 22 rod guide 41 damping force generating mechanism (first damping force generating mechanism)
41A damping force generating mechanism (second damping force generating mechanism)
52 Pilot valve (second main valve)
56 case member (housing)
69 compartment disk (disk)
71 bottom 101 pilot chamber (second pilot chamber)
102 variable chamber (housing inner chamber)
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 (1st pilot room)
401A pilot room (second pilot room)
441 damping force generation mechanism (second damping force generation mechanism)
531 case member (housing)
534 Compartment Disk (Disk)
540 frequency sensitive part case 541 bottom part 544 cylindrical part 571 case chamber (housing inner chamber)

Claims (2)

a cylinder in which the working fluid is sealed;
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 having the other end portion protruding outside the cylinder via a rod guide;
a first passage through which the working fluid flows from one chamber in the cylinder due to the 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 part of the second passage is formed;
a disk movably mounted relative to the housing and forming a housing interior with the bottom of the housing;
has
The first damping force generating mechanism is
a first main valve that suppresses the flow of the working fluid from the upstream chamber to the downstream chamber by sliding of the piston to generate a damping force;
a first pilot chamber that applies pressure to the first main valve in a valve closing direction;
with
a second damping force generating mechanism that suppresses the flow of working fluid from the first pilot chamber to the downstream chamber to generate a damping force;
The second damping force generating mechanism is
a second main valve that suppresses the flow of working fluid from the first pilot chamber to the downstream chamber to generate a damping force;
a second pilot chamber that applies pressure to the second main valve in a valve closing direction;
with
a passage portion provided in the housing, forming at least a portion of the second passage, and communicating between the second pilot chamber and the inside of the cylinder;
a third damping force generating mechanism that suppresses the flow of the working fluid from the passage portion into the cylinder to generate a damping force;
A buffer characterized by comprising: 2. The shock absorber according to claim 1, wherein said second pilot chamber comprises said housing, said disk and said second main valve.

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