JP7055076B2 - Shock absorber - Google Patents

Description

The present invention relates to a shock absorber.

The shock absorber has a main valve that controls the flow of oil and liquid from the upstream chamber to the downstream chamber caused by the sliding of the piston to generate a damping force, and back pressure is applied in the valve closing direction of the main valve. Some have a back pressure chamber (see, for example, Patent Document 1).

Japanese Patent No. 4318080

In the shock absorber, it is required to smooth the damping force characteristic.

Therefore, it is an object of the present invention to provide a shock absorber capable of smoothing the damping force characteristics.

In order to achieve the above object, in the present invention, the damping force generation mechanism is provided at one end with a main valve that provides resistance to the flow of the working fluid from the chamber on the upstream side to the chamber on the downstream side of the first passage. The outer cylinder portion having an opening, the inner cylinder portion through which the piston rod is inserted, and the bottom portion are formed, and the main valve arranged on the opening side is supported by the seat portion of the inner cylinder portion, and the main is inside. It has a bottomed tubular case member that forms a back pressure chamber that applies internal pressure in the valve closing direction of the valve, and a back pressure introduction passage that introduces a working fluid from the chamber on the upstream side into the back pressure chamber. The sheet portion is formed so that the radial width becomes non-uniform in the circumferential direction.

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

It is a front view which made a part of the shock absorber of 1st Embodiment which concerns on this invention as a cross section. It is a partial cross-sectional view which shows the periphery of the piston of the shock absorber of 1st Embodiment which concerns on this invention. It is a partial cross-sectional view which shows the periphery of the damping force generation mechanism on the extension side of the shock absorber of 1st Embodiment which concerns on this invention. It is a partial cross-sectional view which shows the periphery of the frequency sensitive part of the shock absorber of 1st Embodiment which concerns on this invention. It is a top view which shows the pilot case member of the shock absorber of 1st Embodiment which concerns on this invention. It is a characteristic diagram which shows the damping force characteristic of the shock absorber of 1st Embodiment which concerns on this invention. It is a top view which shows the pilot case member of the shock absorber of the 2nd Embodiment which concerns on this invention. It is a top view which shows the pilot case member of the shock absorber of the 3rd Embodiment which concerns on this invention. It is sectional drawing which shows the modification of the frequency sensitive part of the shock absorber of 1st to 3rd Embodiment which concerns on this invention.

[First Embodiment]
The first embodiment according to the present invention will be described with reference to FIGS. 1 to 6. In the following, for convenience of explanation, the upper side in the drawing will be referred to as “upper” and the lower side in the drawing will be referred to as “lower”.

As shown in FIG. 1, the shock absorber 1 of the first embodiment is a so-called double-cylinder type hydraulic shock absorber, and includes a cylinder 2 in which an oil liquid (not shown) as a working fluid is sealed. The cylinder 2 has a cylindrical inner cylinder 3 and a bottomed cylindrical outer cylinder 4 having a diameter larger than that of the inner cylinder 3 and concentrically provided so as to cover the inner cylinder 3. A reservoir chamber 6 is formed between the inner cylinder 3 and the outer cylinder 4. The shock absorber 1 has a cover 7 that covers the upper opening side of the outer cylinder 4, and a main bracket 8 and a spring seat 9 that are both fixed to the outer peripheral side of the outer cylinder 4.

The outer cylinder 4 includes a cylindrical body portion 11 and a cylinder bottom portion 12 that is integrally formed on the lower side of the body portion 11 and closes the lower portion of the body portion 11.

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

The shock absorber 1 includes a piston rod 21 having one end side arranged in the inner cylinder 3 of the cylinder 2 and connected to the piston 18 and the other end side extending to the outside of the cylinder 2. The piston 18 and the piston rod 21 move integrally. In the extension stroke in which the piston rod 21 increases the amount of protrusion from the cylinder 2, the piston 18 moves toward the upper chamber 19, and in the contraction stroke in which the piston rod 21 reduces the amount of protrusion from the cylinder 2, the piston 18 moves downward. It will move to the room 20 side.

A rod guide 22 is fitted on the upper end opening side of the inner cylinder 3 and the outer cylinder 4, and a seal member 23 is mounted on the outer cylinder 4 on the upper side which is the outer side of the cylinder 2 with respect to the rod guide 22. 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 all have an annular shape, and the piston rod 21 is slidably inserted inside 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 rod guide 22 supports the piston rod 21 so as to be movable in the axial direction 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 is in sliding contact with the outer peripheral portion of the piston rod 21 moving in the axial direction at its inner peripheral portion, so that the oil liquid in the inner cylinder 3 and the outer cylinder 4 are in close contact with each other. It prevents the high-pressure gas and the oil liquid in the reservoir chamber 6 from leaking to the outside. The friction member 24 is in sliding contact with the outer peripheral portion of the piston rod 21 at its inner peripheral portion to generate frictional resistance in the piston rod 21. The friction member 24 is not intended for sealing.

The outer peripheral portion of the rod guide 22 has a stepped shape in which the upper portion has a larger diameter than the lower portion, and the rod guide 22 fits into the inner peripheral portion of the upper end of the inner cylinder 3 at the lower portion of the small diameter and has an outer cylinder at the upper portion of the large diameter. It fits into the inner peripheral portion of the upper part of 4. A base valve 25 that defines the lower chamber 20 and the reservoir chamber 6 is installed on the cylinder bottom 12 of the outer cylinder 4, and the inner peripheral portion of the lower end of the inner cylinder 3 is fitted to the base valve 25. ing. The upper end portion of the outer cylinder 4 is crimped inward in the radial direction, and the crimped portion and the rod guide 22 sandwich the seal member 23.

The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28 having a smaller diameter than the main shaft portion 27. The outer peripheral surface of the main shaft portion 27 and the mounting shaft portion 28 is a cylindrical surface coaxial with each other, and the central axis thereof is the central axis of the piston rod 21. The mounting shaft portion 28 is arranged in the cylinder 2 to mount the piston 18 and the like. The end portion of the main shaft portion 27 on the mounting shaft portion 28 side is a shaft step portion 29 extending in the direction orthogonal to the axis of the piston rod 21. On the outer peripheral portion of the mounting shaft portion 28, a passage groove 30 that is recessed inward in the radial direction and extends in the axial direction is formed at an intermediate position in the axial direction, and is on the side opposite to the main shaft portion 27 in the axial direction. A male screw 31 is formed. The passage groove 30 is formed so that the shape of the cross section on the plane orthogonal to the central axis of the piston rod 21 is rectangular, square, or D-shaped.

The piston rod 21 is provided with an annular stopper member 32, a pair of shock absorbers 33, and a coil spring 34 at a portion between the piston 18 of the main shaft portion 27 and the rod guide 22. The stopper member 32 has a piston rod 21 inserted on the inner peripheral side, and is crimped to be fixed to the spindle portion 27. One shock absorber 33, the coil spring 34, and the other shock absorber 33 are arranged in order from the stopper member 32 side. The pair of shock absorbers 33 and the coil spring 34 have a piston rod 21 inserted therein and are arranged between the stopper member 32 and the rod guide 22.

In the shock absorber 1, for example, the protruding portion of the piston rod 21 from the cylinder 2 is arranged at the upper part and supported by the vehicle body, and the main bracket 8 on the cylinder 2 side is arranged at the lower part and connected to the wheel side. On the contrary, 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 wheel vibrates as it travels, the positions of the cylinder 2 and the piston rod 21 change relatively due to the vibration, and the above change is caused by the flow path formed in at least one of the piston 18 and the piston rod 21. It is suppressed by the fluid resistance of. As described in detail below, the fluid resistance of the flow path formed in at least one of the piston 18 and the piston rod 21 is made to differ depending on the speed and amplitude of the vibration, and by suppressing the vibration, the ride comfort is achieved. Is improved. In addition to the vibration generated by the wheels, the inertial force and centrifugal force generated in the vehicle body as the vehicle travels also act between the cylinder 2 and the piston rod 21. For example, a centrifugal force is generated in the vehicle body by changing the traveling direction by operating the steering wheel, and the 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 vibration based on the force generated in the vehicle body as the vehicle travels, and high stability in vehicle travel can be obtained.

As shown in FIG. 2, the piston 18 is integrally mounted on the outer peripheral surface of the metal piston body 35 supported by the mounting shaft portion 28 of the piston rod 21 and the outer peripheral surface of the piston body 35, and slides in the inner cylinder 3. It is composed of a sliding member 36 made of an annular synthetic resin. The central axis of the outer peripheral surface of the piston body 35 is defined as the central axis of the piston body 35, and the central axis of the outer peripheral surface formed by the sliding member 36 of the piston 18 is defined as the central axis of the piston 18. These central axes are aligned.

The piston body 35 has a plurality of passage holes 37 for communicating the upper chamber 19 and the lower chamber 20 (only one place is shown in FIG. 2 due to the cross section), and a plurality of passage holes 37 for communicating the upper chamber 19 and the lower chamber 20. (In FIG. 2, only one place is shown because of the cross section), and the passage hole 39 is provided. The plurality of passage holes 37 are formed at equal pitches with one passage hole 39 sandwiched between them in the circumferential direction, and constitutes half of the passage holes 37 and 39. In the plurality of passage holes 37, one side in the axial direction (upper side in FIG. 2) of the piston 18 is radially outwardly open, and the other side in the axial direction (lower side in FIG. 2) is radially inward.

The passage holes 37 are provided with a damping force generation mechanism 41 that opens and closes the passage portion in the passage holes 37 to generate a damping force. The damping force generation mechanism 41 is arranged on the lower chamber 20 side in the axial direction, which is one end side in the axial direction of the piston 18, and is attached to the piston rod 21. By arranging the damping force generation mechanism 41 on the lower chamber 20 side, the passage portion formed inside each of the plurality of passage holes 37 moves to the upper chamber 19 side of the piston 18, that is, in the extension stroke. It is a passage through which oil liquid as a working fluid flows out from the upper chamber 19 (upstream chamber) on the upstream side of the above chamber to the lower chamber 20 (downstream chamber) on the other downstream side. The damping force generation mechanism 41 provided for the passage portion in the passage hole 37 suppresses the flow of the oil liquid in the passage portion in the passage hole 37 on the extension side to generate the damping force. It is a generation mechanism.

The passage holes 39, which form the other half of the passage holes 37 and 39, are formed at equal pitches with one passage hole 37 sandwiched between them in the circumferential direction, and are formed in the axial direction of the piston 18 and the like. The side (lower side in FIG. 2) opens radially outward and the axial one side (upper side in FIG. 2) opens radially inward.

The passage holes 39 are provided with a damping force generation mechanism 42 that opens and closes the passage portion in the passage holes 39 to generate a damping force. The damping force generation mechanism 42 is arranged on the upper chamber 19 side in the axial direction, which is the other end side in the axial direction of the piston 18, and is attached to the piston rod 21. By arranging the damping force generation mechanism 42 on the upper chamber 19 side, the passage portion formed inside each of the plurality of passage holes 39 moves to the lower chamber 20 side of the piston 18, that is, upstream in the contraction stroke. It is a passage through which the oil liquid flows from the lower chamber 20 on the side to the upper chamber 19 on the downstream side. The damping force generation mechanism 42 provided for the passage portion in the passage hole 39 suppresses the flow of the oil liquid in the passage portion in the passage hole 39 on the contraction side to generate the damping force. It is a force generation mechanism.

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

The piston body 35 has a substantially disk shape, and a fitting hole 45 for fitting the mounting shaft portion 28 of the piston rod 21 is formed at the center in the radial direction thereof so as to penetrate in the axial direction. ing. The piston body 35 and the piston 18 including the piston body 35 are coaxial with the piston rod 21 in a state of being fitted to the mounting shaft portion 28.

At the end of the piston body 35 on the lower chamber 20 side in the axial direction, an annular valve seat portion constituting a part of the damping force generating mechanism 41 is radially outside the opening on the lower chamber 20 side of the passage hole 37. 47 is formed. Further, at the end of the piston body 35 on the lower chamber 20 side in the axial direction, an annular holding sheet portion 501 is formed radially inside the opening on the lower chamber 20 side of the passage hole 37.

As shown in FIG. 3, the sandwiching sheet portion 501 has a flat sandwiching sheet surface 502 in which the end surface of the piston body 35 on the lower chamber 20 side in the axial direction extends in the direction orthogonal to the axis of the piston body 35. The outer peripheral surface of the piston 18 and the fitting hole 45 constituting the inner peripheral surface coincide with the central axis, and the outer peripheral surface of the sandwiching sheet portion 501 also aligns with the central axis. As a result, the outer shape of the sandwiching sheet portion 501 has a circular shape centered on the central axis of the piston 18. The outer shape of the sandwiching sheet surface 502 of the sandwiching sheet portion 501, that is, the outer peripheral edge portion 503 also has a circular shape centered on the central axis of the piston 18. The sandwiching sheet surface 502 has a constant outer diameter over the entire circumference, in other words, the outer peripheral edge portion 503 has a circular shape with a constant diameter.

The inner shape of the sandwiching sheet portion 501 also has a circular shape centered on the central axis of the piston 18. The inner shape of the holding seat surface 502 of the holding seat portion 501, that is, the inner peripheral edge portion 504 also has a circular shape centered on the central axis of the piston 18. The width of the sandwiching seat surface 502 is constant over the entire circumference of the piston 18 in the circumferential direction.

As shown in FIG. 2, at the end of the piston body 35 on the upper chamber 19 side in the axial direction, a part of the damping force generating mechanism 42 is radially outside the opening on the upper chamber 19 side of the passage hole 39. An annular valve seat portion 49 is formed. The fitting hole 45 of the piston body 35 has a small diameter hole portion 201 for fitting the mounting shaft portion 28 of the piston rod 21, and a large diameter hole portion 202 formed to have a larger diameter than the small diameter hole portion 201. There is. The small diameter hole portion 201 is formed on the valve seat portion 49 side in the axial direction of the piston body 35, and the large diameter hole portion 202 is closer to the valve seat portion 47 side than the small diameter hole portion 201 in the axial direction of the piston body 35. It is formed. In the piston body 35, an opening on the lower chamber 20 side in the passage hole 39 on the contraction side is arranged on the side opposite to the fitting hole 45 of the valve seat portion 47, and the fitting hole 45 of the valve seat portion 49 On the opposite side, an opening on the upper chamber 19 side of the passage hole 37 on the extension side is arranged.

As shown in FIG. 3, on the lower chamber 20 side of the piston 18, one disk 51, one disk 210, one disk 211, and one disk are ordered from the piston 18 side in the axial direction. A disk 212, a plurality of (specifically, three) disks 213, one piston valve 52, and one piston case member 55 (case member) are stacked.

As shown in FIG. 4, the pilot case member 55 includes one disc 56, a plurality of (specifically five) discs 57, and a plurality of discs (specifically, five) in order from the pilot case member 55 side in the axial direction. Specifically, two discs 58, a plurality of (specifically two) discs 59, a plurality of (specifically two) discs 60, and one disc 61, one. The discs 62 are overlapped with each other.

The disks 51, 56 to 62, 210 to 213 and the pilot case member 55 shown in FIGS. 3 and 4 are made of metal. The disks 51, 56 to 62, 210 to 213 all have a perforated flat plate shape having a constant thickness to which the mounting shaft portion 28 of the piston rod 21 can be fitted inside. The disks 51, 56 to 60, 62, 211 to 213 are provided so as to be flexible. Both the pilot valve 52 and the pilot case member 55 have an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted. The disks 51, 56 to 62, 210 to 213 have a disk shape.

The disks 51, 210 to 213 and the pilot valve 52 shown in FIG. 3 are main valves 231 constituting the damping force generation mechanism 41 together with the valve seat portion 47 of the piston 18. The inner peripheral side of the main valve 231 is supported by the holding seat portion 501 at the end of the lower chamber 20 side in the axial direction of the piston body 35, and the main valve 231 is taken off and seated with respect to the valve seat portion 47. The disks 51, 210 to 213, the pilot valve 52, and the main valve 231 including these are coaxial with the piston rod 21 in a state of being fitted to the mounting shaft portion 28. The main valve 231 is provided in the passage portion in the passage hole 37 formed in the piston 18 and suppresses the flow of the oil liquid generated by sliding the piston 18 to the extension side (upper side in FIG. 3) to suppress the damping force. generate.

The pilot case member 55 includes a perforated disk-shaped bottom portion 71, a cylindrical inner cylinder portion 72 protruding unilaterally from the inner peripheral side of the bottom portion 71 along the axial direction of the bottom portion 71, and an outer peripheral side of the bottom portion 71. It is integrally molded into a bottomed cylinder having a cylindrical outer cylinder 73 protruding to the same side as the inner cylinder 72 along the axial direction of the bottom 71. The bottom portion 71 and the outer cylinder portion 73 have the same central axis, and this central axis is used as the central axis of the pilot case member 55. The bottom portion 71 is formed with a through hole 74 that penetrates the pilot case member 55 in the axial direction in the range between the inner cylinder portion 72 and the outer cylinder portion 73. As shown in FIG. 5, a plurality of through holes 74 are formed at equal intervals in the circumferential direction of the pilot case member 55, specifically, six locations.

As shown in FIG. 3, the inner peripheral side of the pilot case member 55, that is, the inner peripheral side of the inner cylinder portion 72 and the bottom portion 71, is inserted through the pilot case member 55 axially at the center in the radial direction of the pilot case member 55. It is a hole 69. The mounting shaft portion 28 of the piston rod 21 is fitted into the insertion hole 69. The pilot case member 55 is coaxial with the piston rod 21 in a state of being fitted to the mounting shaft portion 28.

The insertion hole 69 has a small diameter hole portion 75 on which the inner cylinder portion 72 side in the axial direction of the pilot case member 55 fits the mounting shaft portion 28 of the piston rod 21, and the inner cylinder portion in the axial direction of the pilot case member 55. The side opposite to the 72 side is the large diameter hole portion 76 having a larger diameter than the small diameter hole portion 75. The outer cylinder portion 73 has an opening 77 on the side opposite to the bottom portion 71. The pilot case member 55 includes an outer cylinder portion 73 having an opening 77 at one end, an inner cylinder portion 72 into which the piston rod 21 is inserted, and a bottom portion 71 connecting them.

The bottom 71 of the pilot case member 55 has a perforated disk-shaped bottom main body 70 and a tubular portion 72 inside the bottom main body 70 in the axial direction of the pilot case member 55 from the inner peripheral side of the bottom main body 70. An annular protrusion 78 projecting to the opposite side and an annular valve projecting from the outer peripheral side of the bottom body 70 to the side opposite to the outer cylinder 73 from the bottom body 70 in the axial direction of the pilot case member 55. It has a seat portion 79 and. In other words, the bottom 71 has a protrusion 78 that protrudes on the inner peripheral side from the bottom main body 70 to the side opposite to the inner cylinder 72, and the outer peripheral side is opposite to the outer cylinder 73 from the bottom main body 70. Valve seat portions 79 projecting to the side are formed respectively. The through hole 74 is formed in a portion between the protruding portion 78 of the bottom main body portion 70 and the valve seat portion 79. A flow path groove 81 that crosses the protrusion 78 in the radial direction is partially formed in the circumferential direction. The flow path groove 81 is open to the large-diameter hole portion 76, and crosses the contact portion of the protrusion 78 with the disk 56 in the radial direction.

The end of the inner cylinder portion 72 of the pilot case member 55 in the axial direction opposite to the protruding portion 78 is an annular holding seat portion 511 (seat portion) that supports the main valve 231. The holding sheet portion 511 has a flat holding sheet surface 512 whose end surface on the side opposite to the protruding portion 78 in the axial direction of the pilot case member 55 extends in the direction orthogonal to the axis of the pilot case member 55. In the pilot case member 55, the inner cylinder portion 72 includes the holding sheet portion 511 and is integrally molded with the bottom portion 71 and the outer cylinder portion 73.

As shown in FIG. 5, the sandwiching sheet surface 512 has a constant outer diameter over the entire circumference, in other words, the outer peripheral edge portion 513 thereof has a circular shape with a constant diameter. The sandwiching sheet surface 512 has a constant inner diameter over the entire circumference, in other words, the inner peripheral edge portion 514 has a circular shape with a constant diameter smaller than that of the outer peripheral edge portion 513.

In the pilot case member 55, the outer peripheral surface of the inner cylinder portion 72 is eccentric to one side in the radial direction with respect to the central axis of the pilot case member 55, which is the central axis of the insertion hole 69, the outer cylinder portion 73, and the bottom portion 71. As a result, the outer shape of the sandwiching sheet portion 511 of the inner cylinder portion 72 is circular and is eccentric to one side in the direction orthogonal to the central axis of the pilot case member 55. Therefore, the outer shape of the holding sheet surface 512 of the holding sheet portion 511, that is, the outer peripheral edge portion 513 is also circular and is eccentric to one side in the direction orthogonal to the central axis of the pilot case member 55. In other words, the holding sheet surface 512 has its outer peripheral edge portion 513 eccentric with respect to its inner peripheral edge portion 514. Therefore, the sandwiching sheet portion 511 is formed so that the radial width of the sandwiching sheet surface 512, which is the width in the radial direction of the pilot case member 55, is not constant over the entire circumference and is non-uniform in the circumferential direction. .. In other words, the radial width of the sandwiched sheet surface 512 differs depending on the circumferential position.

As a result, the outer peripheral edge portion 513 of the sandwiching sheet surface 512 has the shortest distance portion 515 that minimizes the distance from the central axis of the inner peripheral edge portion 514, that is, the central axis of the pilot case member 55, and the central axis of the pilot case member 55. It has a longest distance portion 516 having a maximum distance from the pilot case member 55, and the distance from the central axis of the pilot case member 55 increases from the shortest distance portion 515 toward the longest distance portion 516. In other words, the radial width of the sandwiched sheet surface 512 is narrowest at the position of the shortest separation portion 515, widens toward the longest separation portion 516, and widens at the position of the longest separation portion 516.

The straight line connecting the shortest distance portion 515 and the longest distance portion 516 of the outer peripheral edge portion 513 of the sandwiched sheet surface 512 passes through the central axis of the pilot case member 55. In other words, on the outer peripheral edge portion 513 of the sandwiching sheet surface 512, the shortest separation portion 515 and the longest separation portion 516 are arranged at positions different from each other by 180 degrees.

Here, the distance of the shortest separation portion 515 from the central axis of the pilot case member 55 is constant at the radius of the outer peripheral portion of the disk 210 shown in FIG. 3 and the constant outer peripheral edge portion 503 of the holding seat surface 502 of the piston 18. It is almost equivalent to a certain radius. Therefore, the distance of the longest separation portion 516 from the central axis of the pilot case member 55 is larger than the radius of the outer peripheral portion of the disk 210 and the radius of the outer peripheral edge portion 503 of the holding seat surface 502 of the piston 18.

The disk 51 shown in FIG. 3 has an outer diameter smaller than the inner diameter of the valve seat portion 47. The disk 51 is formed with a notch 87 extending radially outward from the inner peripheral edge portion fitted to the mounting shaft portion 28 of the piston rod 21. The passage portion in the notch 87 is always in communication with the passage portion in the passage hole 37 of the piston 18, and the passage portion in the passage hole 37 passes through the passage portion in the notch 87 and has a large diameter of the piston 18. It is always in communication with the passage portion in the hole portion 202 and the passage portion in the passage groove 30 of the piston rod 21. The inner peripheral side of the disk 51 is in contact with the holding sheet surface 502 of the holding sheet portion 501 of the piston body 35 by surface contact. The outer diameter of the sandwiched sheet surface 502, that is, the diameter of the outer peripheral edge portion 503 is smaller than the outer diameter of the disk 51.

The disk 210 has an outer diameter smaller than the outer diameter of the disk 51, and has a diameter substantially equal to that of the outer peripheral edge portion 503 of the sandwiching sheet surface 502 of the sandwiching sheet portion 501. The disk 211 has an outer diameter substantially equal to the outer diameter of the valve seat portion 47 of the piston 18. The disk 211 is in contact with the valve seat portion 47, and is separated from and in contact with the valve seat portion 47 to open and close the opening of the passage portion in the passage hole 37 formed in the piston 18. The disk 211 is formed with a passage hole 221 extending in the circumferential direction of the disk 211 so as to penetrate the disk 211 in the axial direction.

The disc 212 has the same outer diameter as the disc 211. The disk 212 is formed with a notch 224 on the outer peripheral side. When the discs 211 and the discs 212 are overlapped with their centers aligned, the passage holes 221 and the notches 224 overlap and communicate with each other by overlapping the radial positions of the discs 211 and 212.

The passage portion in the passage hole 221 of the disk 211 and the passage portion in the notch 224 of the disk 212 are fixed orifices 227 that always communicate the passage portion in the passage hole 37 with the lower chamber 20. That is, in this fixed orifice 227, the oil liquid introduced from the upper chamber 19 into the passage hole 37 flows from the passage portion in the passage hole 221 to the lower chamber 20 through the passage portion in the notch 224.

The disc 213 has the same outer diameter as the disc 212. By overlapping the disk 213 with the center aligned with the disk 212, the side of the notch 224 opposite to the disk 211 is completely closed.

The outer peripheral portion of the disc 211 is a continuous circle over the entire circumference, and in the main valve 231 the disc 211 abuts on the valve seat portion 47 of the piston 18 to close the opening of the passage portion in the passage hole 37, and the disc 211 is used. The opening of the passage portion in the passage hole 37 is opened apart from the valve seat portion 47.

The pilot valve 52 includes a metal disc 85 and a rubber sealing member 86 fixed to the disc 85. The disk 85 has a perforated circular flat plate shape having a constant thickness to which the mounting shaft portion 28 of the piston rod 21 can be fitted inside, and is flexible. The disc 85 has an outer diameter larger than the outer diameter of the discs 211 to 213. The seal member 86 is fixed to the outer peripheral side of the disk 85 opposite to the piston 18 in the axial direction, and forms an annular shape. In other words, the pilot valve 52 has an annular seal member 86 on the outer peripheral side thereof.

The pilot valve 52 is arranged on the opening 77 side of the outer cylinder portion 73 of the pilot case member 55. Between the pilot valve 52, the bottom portion 71 of the pilot case member 55, the inner cylinder portion 72, and the outer cylinder portion 73, there is a back pressure chamber 80 that applies pressure to the pilot valve 52, that is, the main valve 231 in the direction of the piston 18. There is. The back pressure chamber 80 also extends into the through hole 74 of the bottom 71 and between the protrusion 78 and the valve seat portion 79.

In the pilot valve 52, the minimum radius of the seal member 86 is longer than the distance from the central axis of the pilot case member 55 to the longest separation portion 516 shown in FIG. 5 of the sandwiching seat surface 512, as shown in FIG. The inner peripheral side of the disk 85 comes into contact with the holding sheet surface 512 of the inner cylinder portion 72 of the pilot case member 55 by surface contact. In other words, the pilot case member 55 directly supports the pilot valve 52 arranged on the opening 77 side of the outer cylinder portion 73 by the holding seat portion 511 of the inner cylinder portion 72.

The piston rod 21, the main valve 231 including the pilot valve 52, and the pilot case member 55 are arranged coaxially, and the holding seat surface 512 of the pilot case member 55 has a piston rod at its outer peripheral edge portion 513. It is eccentric in the radial direction with respect to the insertion hole 69 fitted to the 21. Therefore, the outer peripheral edge portion 513 of the sandwiching seat surface 512 is radially eccentric with respect to the disc 85 of the pilot valve 52.

As a result, the holding seat portion 511 has the shortest support length for supporting the pilot valve 52 in the radial direction of the pilot case member 55 at the position of the shortest separating portion 515 in the circumferential direction of the pilot case member 55, and the shortest separating portion. It becomes longer from 515 toward the longest separation portion 516, and becomes the longest at the position of the longest separation portion 516. In other words, the length of the portion of the pilot valve 52 that is not supported by the holding seat portion 511 in the radial direction is the longest at the position of the shortest separation portion 515 in the circumferential direction of the pilot case member 55, and is the longest from the shortest separation portion 515. It becomes shorter toward the separation portion 516 and becomes the shortest at the position of the longest separation portion 516.

The seal member 86 is slidably and liquid-tightly fitted to the inner peripheral surface of the outer cylinder portion 73 of the pilot case member 55 over the entire circumference, and constantly seals the gap between the pilot valve 52 and the outer cylinder portion 73. do. In other words, the pilot valve 52 slidably and tightly fits the seal member 86 to the outer cylinder portion 73 of the pilot case member 55. As a result, the pilot valve 52 and the pilot case member 55 form the above-mentioned back pressure chamber 80 between each other.

Therefore, the main valve 231 including the pilot valve 52 is arranged on the opening 77 side of the outer cylinder portion 73 of the pilot case member 55, and forms a back pressure chamber 80 inside the pilot case member 55. The back pressure chamber 80 between the pilot valve 52 and the pilot case member 55 applies internal pressure to the main valve 231 in the direction of the piston 18, that is, in the valve closing direction in which the disk 211 is seated on the valve seat portion 47. In other words, the pilot case member 55 supports the main valve 231 arranged on the opening 77 side of the outer cylinder portion 73 by the sandwiching seat portion 511 of the inner cylinder portion 72, and internally presses the main valve 231 in the valve closing direction. The back pressure chamber 80 is formed.

The main valve 231 is a pilot type damping valve having a back pressure chamber 80, and these main valves 231 and the back pressure chamber 80 form a part of the damping force generation mechanism 41. In other words, the damping force generation mechanism 41 includes a main valve 231 and a back pressure chamber 80, and is a pressure control type valve mechanism. The main valve 231 is formed with a fixed orifice 227 that constantly communicates between the passage portion in the passage hole 37 and the lower chamber 20, in other words, the two upper chambers 19 and the lower chamber 20 that constantly communicate with each other.

The outer tubular portion 73 of the pilot case member 55 abuts on the outer peripheral side of the seal member 86 of the disc 85 of the pilot valve 52, and suppresses deformation of the main valve 231 beyond the specified direction in the opening direction.

The passage portion in the flow path groove 81 formed in the bottom portion 71 of the pilot case member 55 is always in communication with the back pressure chamber 80. The back pressure chamber 80 is constantly communicated with the passage portion in the large-diameter hole portion 76 of the pilot case member 55 and the passage portion in the passage groove 30 of the piston rod 21 via the passage portion in the flow path groove 81. ing.

The passage portion in the notch 87 of the disk 51, the passage portion in the large diameter hole portion 202 of the piston 18, the passage portion in the passage groove 30 of the piston rod 21, and the passage portion in the large diameter hole portion 76 of the pilot case member 55. The passage portion and the passage portion in the passage groove 81 of the pilot case member 55 always communicate with the passage portion in the passage hole 37 of the piston 18 and the back pressure chamber 80, and from the upper chamber 19 to the inside of the passage hole 37. It is a back pressure introduction passage 235 that introduces an oil liquid into the back pressure chamber 80 through the passage portion of the above. The back pressure introduction passage 235 introduces the oil liquid from the upper chamber 19 on the upstream side into the back pressure chamber 80 in the extension stroke. Therefore, the back pressure introduction passage 235 includes a passage portion in the flow path groove 81 formed in the bottom portion 71 of the pilot case member 55. In other words, the back pressure introduction passage 235 is partially provided at the bottom 71 of the pilot case member 55.

When the disk 211 of the main valve 231 is opened apart from the valve seat portion 47 of the piston 18, oil liquid from the passage portion in the passage hole 37 is supplied to the piston 18 and the outer cylinder portion 73 of the pilot case member 55. It flows to the lower chamber 20 through the passage portion 88 extending in the radial direction between them. A passage portion formed inside each of the plurality of passage holes 37, a passage portion 88 between the main valve 231 and the valve seat portion 47, and a passage portion 88 between the piston 18 and the outer cylinder portion 73 of the pilot case member 55. Consists of the passage 101 (first passage).

In this passage 101, the oil liquid as a working fluid flows out from the upper chamber 19 which is one upstream side to the lower chamber 20 which is the other downstream side in the movement of the piston 18 to the upper chamber 19 side, that is, in the extension stroke. It becomes a passage on the extension side. The extension side damping force generation mechanism 41 including the valve seat portion 47 and the main valve 231 is provided in this passage 101, and the main valve 231 opens and closes this passage 101 to suppress the flow of oil and liquid. Generates damping force. In other words, the main valve 231 provides resistance to the flow of working fluid from the upper chamber 19 on the upstream side of the passage 101 to the lower chamber 20 on the downstream side. Then, the damping force generation mechanism 41 on the extension side introduces a part of the flow of the oil liquid in the passage 101 into the back pressure chamber 80 via the back pressure introduction passage 235, and the pressure of the back pressure chamber 80 causes the main valve 231 to move. Control valve opening.

The disk 56 has an outer diameter smaller than the inner diameter of the valve seat portion 79 of the pilot case member 55 and a larger diameter than the outer diameter of the protruding portion 78. No groove or the like for forming a flow path is formed in the disk 56. The plurality of discs 57 have an outer diameter substantially equal to the outer diameter of the valve seat portion 79, and can be seated on the valve seat portion 79.

As shown in FIG. 4, the disc 58 has an outer diameter smaller than the outer diameter of the disc 57. The disk 59 has an outer diameter smaller than the outer diameter of the disk 58. The disc 60 has an outer diameter smaller than the outer diameter of the disc 59. The disk 61 has an outer diameter smaller than the outer diameter of the disk 60. The disc 62 has an outer diameter equivalent to the outer diameter of the disc 59.

The disks 56 to 60 constitute a sub-valve 99 that can be taken off and seated on the valve seat portion 79. The sub-valve 99 sits on the valve seat portion 79 on the disc 57 and partitions the back pressure chamber 80 described above inside the valve seat portion 79. The sub-valve 99 communicates the back pressure chamber 80 and the lower chamber 20 by separating from the valve seat portion 79. The sub valve 99 suppresses the flow of oil liquid between the back pressure chamber 80 and the lower chamber 20. The back pressure chamber 80 applies pressure to the sub-valve 99 that abuts on the valve seat portion 79 in a direction away from the valve seat portion 79. The passage portion formed inside each of the plurality of passage holes 37 of the piston 18, the back pressure introduction passage 235, the back pressure chamber 80, and the space between the sub valve 99 and the valve seat portion 79 are one with the passage 101. A passage 103 is provided in parallel and connects the upper chamber 19 and the lower chamber 20.

The sub-valve 99 separates from the valve seat portion 79 and opens the passage 103 when the pressure in the back pressure chamber 80 reaches a predetermined pressure. The sub-valve 99, together with the valve seat portion 79, constitutes a damping force generation mechanism 105 that opens when the pressure in the back pressure chamber 80 reaches a predetermined pressure and opens a passage 103 to generate a damping force. The sub-valve 99 is opened by the pressure of the back pressure chamber 80 to allow an oil liquid to flow from the passage 103 to the lower chamber 20, and at that time, a resistance force is given to the flow of the oil liquid.

The disk 62 comes into contact with the sub-valve 99 when the sub-valve 99 is deformed in the opening direction, and the deformation of the sub-valve 99 beyond the specified value is suppressed by the case member 131 (housing member) described later.

As shown in FIG. 2, on the upper chamber 19 side of the piston 18, one disk 110, one disk 111, one disk 112, and a plurality of sheets (in order from the piston 18 side in the axial direction). Specifically, two discs 113, a plurality of discs 115 (specifically two discs), one disc 116, and a plurality of discs 117 (specifically two discs). A disk 118, a disk 119, and an annular member 120 are stacked. The disks 110 to 119 and the annular member 120 are all made of metal, and both have a perforated circular flat plate shape having a constant thickness to which the mounting shaft portion 28 of the piston rod 21 can be fitted. The disks 111 to 117 and 119 are provided so as to be flexible.

The disk 110 has an outer diameter smaller than the inner diameter of the valve seat portion 49 of the piston 18. The disk 111 has an outer diameter substantially equal to the outer diameter of the valve seat portion 49 of the piston 18. The disk 111 is in contact with the valve seat portion 49, and is separated from and in contact with the valve seat portion 49 to open and close the opening of the passage portion in the passage hole 39 formed in the piston 18. The disk 111 is a common component with the disk 211, and has a passage hole 121 similar to the passage hole 221 of the disk 211. The disk 112 has the same outer diameter as the disk 111. The disk 112 is a common component with the disk 212, and has a notch 124 similar to the notch 224 of the disk 212.

The passage portion in the passage hole 121 of the disk 111 and the passage portion in the notch 124 of the disk 112 are fixed orifices 127 similar to the fixed orifice 227. The fixed orifice 127 always communicates the passage portion in the passage hole 39 with the upper chamber 19.

The disk 113 has the same outer diameter as the disk 112. By overlapping the disk 112, the disk 113 closes the entire side of the plurality of notches 124 opposite to the disk 111.

The outer peripheral portion of the disc 111 is a continuous circle over the entire circumference, and the disc 111 abuts on the valve seat portion 49 of the piston 18 and is separated and abutted on the valve seat portion 49 to form a passage hole in the piston 18. The opening of the passage in 39 is opened and closed.

The plurality of discs 115 have an outer diameter smaller than the outer diameter of the disc 113. The disc 116 has an outer diameter smaller than the outer diameter of the disc 115. The plurality of discs 117 have an outer diameter smaller than the outer diameter of the disc 116. The disc 118 has an outer diameter smaller than the outer diameter of the disc 117. The disk 119 has an outer diameter equivalent to the outer diameter of the disk 116. The annular member 120 has an outer diameter smaller than the outer diameter of the disc 119, and is thicker and more rigid than the discs 110 to 119. The annular member 120 is in contact with the shaft step portion 29 of the piston rod 21.

The disks 110 to 117 can be taken off and seated on the valve seat portion 49, and the passage portion in the passage hole 39 can be opened to the upper chamber 19 by taking off from the valve seat portion 49, and the upper chamber 19 and the lower part can be opened. It constitutes a disc valve 129 that suppresses the flow of oil liquid to and from the chamber 20. The disc valve 129 and the valve seat portion 49 form a damping force generation mechanism 42 on the contraction side. The inner peripheral side of the disc valve 129 of the damping force generation mechanism 42 is supported by a portion between the fitting hole 45 and the passage hole 39 at the end of the piston body 35 on the upper chamber 19 side in the axial direction. The disc valve 129 is formed with a fixed orifice 127 that always communicates between the upper chamber 19 and the lower chamber 20 even when the disc valve 129 is in contact with the valve seat portion 49. The disc 119 and the annular member 120 contact the disc valve 129 to suppress deformation of the disc valve 129 in the opening direction or more.

In the present embodiment, the compression side disc valve 129 shown in FIG. 2 and the extension side sub valve 99 shown in FIG. 4 are both shown as examples of a disc valve having an inner peripheral clamp, but the damping force is not limited to this. Any mechanism may be used as long as it is generated, and for example, a lift type valve in which the disc valve is urged by a coil spring may be used, or a poppet valve may be used.

As shown in FIG. 4, the mounting shaft portion 28 of the piston rod 21 has a frequency of reciprocating movement of the piston 18 (hereinafter referred to as a piston frequency) on the side opposite to the pilot case member 55 of the damping force generating mechanism 105. A frequency-sensitive unit 43 that is sensitive and has a variable damping force is attached. The frequency-sensitive unit 43 includes a case member 131, which is one housing member that abuts on the disc 62, and a plurality of (specifically, two) discs 133 and one in order from the axial damping force generation mechanism 105 side. It has a partition disk 134 (definition member), one disk 135, one disk 136, and a lid member 139.

The case member 131, the disc 133, 135, 136 and the lid member 139 are made of metal. The disks 133, 135, and 136 each have a perforated circular flat plate shape having a constant thickness to which the mounting shaft portion 28 of the piston rod 21 can be fitted inside. The case member 131 and the lid member 139 have an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted. The case member 131 and the lid member 139 form a box-shaped frequency-sensitive portion case 140. A part of the mounting shaft portion 28 of the piston rod 21 is arranged inside the case member 131.

The case member 131 is integrated into a bottomed tubular shape having a perforated disk-shaped bottom portion 141 and a cylindrical outer tubular portion 144 protruding from the outer peripheral side of the bottom portion 141 to one side along the axial direction of the bottom portion 141. It is molded. The bottom portion 141 includes a perforated disk-shaped bottom main body portion 147, and an annular protrusion 142 that protrudes from the inner peripheral side of the bottom main body portion 147 toward the outer tubular portion 144 in the axial direction from the bottom main body portion 147. It has an annular support portion 143 that protrudes from between the protrusion 142 and the outer cylinder portion 144 of the bottom main body portion 147 toward the outer cylinder portion 144 in the axial direction from the bottom main body portion 147. In other words, the bottom portion 141 has a protruding portion 142 projecting to the same side as the outer cylinder portion 144 from the bottom main body portion 147 on the inner peripheral side, and the same as the outer cylinder portion 144 from the bottom main body portion 147 at the radial intermediate position. Support portions 143 projecting to the side are formed respectively.

A flow path groove 148 that crosses the protrusion 142 in the radial direction is partially formed in the circumferential direction. In the support portion 143, a flow path groove 203 that crosses the support portion 143 in the radial direction is partially formed in the circumferential direction. On the inner peripheral side of the bottom portion 141, a small diameter hole portion 145 for fitting the mounting shaft portion 28 of the piston rod 21 is formed on the side opposite to the axially protruding portion 142, and on the axially protruding portion 142 side. A large-diameter hole portion 146 having a larger diameter is formed than the small-diameter hole portion 145. The flow path groove 148 is open to the large diameter hole portion 146. The side of the outer cylinder portion 144 opposite to the bottom portion 141 is an opening portion 149. Therefore, the case member 131 is composed of an outer cylinder portion 144 having an opening portion 149 at one end and a bottom portion 141. The lid member 139 is provided in the opening 149 of the outer tubular portion 144 of the case member 131, and the box-shaped frequency-sensitive portion case 140 is composed of the tubular case member 131.

The mounting shaft portion 28 penetrates the radial center of the case member 131 in the axial direction, and a plurality of discs 133, partition discs 134, discs 135, and discs 136 each penetrate the mounting shaft portion 28 in the case member 131. It is placed so that it penetrates inside.

The bottom portion 141 of the case member 131 supports the inner peripheral side of the disc 62 at the outer end portion on the small diameter hole portion 145 side in the axial direction, and the disc is supported at the inner end portion on the large diameter hole portion 146 side in the axial direction. It supports the outer peripheral side of 133. The support portion 143 of the case member 131 supports the radial intermediate position of the annular partition disk 134 at the end portion on the protruding tip side thereof. The support portion 143 always communicates with the radial inner side and the radial outer side of the support portion 143 in the case member 131 by the flow path groove 203.

The plurality of discs 133 have an outer diameter smaller than the outer diameter of the protruding portion 142 of the case member 131. The flow path groove 148 crosses the contact portion of the protrusion 142 with the disk 133 in the radial direction.

The partition disk 134 is composed of a perforated circular flat plate-shaped flexible disk 155 made of a metal material and an elastic sealing member 156 made of a rubber material fixed to the outer peripheral side of the disk 155. The partition disk 134 is circular as a whole and is elastically deformable, that is, flexible. The inner diameter of the annular disc 155 is larger than the outer diameter of the disc 133, and the inner diameter of the annular disc 155 is such that the disc 133 can be arranged with a gap in the radial direction inside the disc 133. The disc 155 is thinner than the thickness of the number of discs 133 (two discs). The disk 155 has an outer diameter larger than the outer diameter of the support portion 143 of the case member 131 and a smaller diameter than the inner diameter of the outer cylinder portion 144. The disk 155 is arranged in the case member 131 so as to penetrate the mounting shaft portion 28 inward. The disk 155 is provided at the bottom 141 in the case member 131.

The elastic sealing member 156 is fixed to the outer peripheral side of the disc 155 in an annular shape. The entire surface of the elastic sealing member 156 facing the disc 155 is fixed to the disc 155. The elastic seal member 156 has a seal portion 158 projecting from the disc 155 to the side opposite to the lid member 139 in the axial direction, and a stopper portion 159 projecting from the disc 155 to the lid member 139 side in the axial direction. The seal portion 158 is formed in a continuous annular cylinder shape over the entire circumference of the disc 155, and is fixed to the disc 155 over the entire circumference. The seal portion 158 is slidably and liquid-tightly fitted to the inner peripheral surface of the outer cylinder portion 144 of the case member 131 over the entire circumference, and is constantly sealed between the seal portion 158 and the outer cylinder portion 144.

The stopper portion 159 is formed intermittently in the circumferential direction of the disc 155. The stopper portion 159 abuts on the lid member 139 and elastically deforms when the partition disk 134 is deformed toward the lid member 139 side, and as a result, the partition disk 134 is suppressed from further deformation. The seal portion 158 covers the outer peripheral surface of the disc 155 and is connected to the stopper portion 159.

The partition disk 134 is centered with respect to the case member 131 when the elastic sealing member 156 comes into contact with the outer tubular portion 144 of the case member 131. Further, the partition disk 134 is supported by the disk 155 in contact with the support portion 143 of the case member 131.

The protruding portion 142 and the disk 135 of the case member 131 have an outer diameter larger than the inner diameter of the disk 155 of the partition disk 134. As a result, in the partition disk 134, the inner peripheral side of the disk 155 is arranged between the protruding portion 142 of the case member 131 and the disk 135. The partition disk 134 is supported by the disk 155 in contact with the support portion 143 and the disk 135 in a state where there is no pressure difference between the front side and the back side. The disc 135 is a seat portion on which the compartment disc 134 is seated.

In the partition disk 134, the inner peripheral side of the disk 155 can be moved between the projecting portion 142 of the case member 131 and the disk 135 within the range of the axial length of the plurality of disks 133. Further, the partition disk 134 is provided with an annular elastic sealing member 156 that seals between the partition disk 134 and the case member 131 on the outer peripheral side which is the non-supporting side opposite to the support by the disk 135 of the disk 155. The partition disk 134 has a simple support structure in which the inner peripheral side thereof is supported by the disk 135 only on one side without being clamped from both sides. The disk 136 has an outer diameter larger than the outer diameter of the disk 135.

The lid member 139 is integrally molded into a disk shape having a cylindrical tubular portion 261 and a disk-shaped flange portion 262 extending radially outward from the axial center position of the outer peripheral portion of the tubular portion 261. Has been done. The tubular portion 261 is thicker in the axial direction than the flange portion 262. The lid member 139 fits the mounting shaft portion 28 of the piston rod 21 inside the tubular portion 261. The lid member 139 is fitted in the outer tubular portion 144 of the case member 131 at the outer peripheral portion of the flange portion 262 to form the frequency sensitive portion case 140.

The lid member 139 has a plurality of grooves 264, which are concave inward in the radial direction from the outer peripheral surface which is a cylindrical surface, on the outer peripheral portion of the flange portion 262 so as to cross the flange portion 262 in the axial direction (one side cross section in FIG. 4). Due to the above relationship, only one place is shown). The lid member 139 in a state of being fitted to the outer cylinder portion 144 of the case member 131 at the flange portion 262 has a lower chamber 20 in the frequency sensitive portion case 140 while the passage portion in the groove 264 is between the outer cylinder portion 144 and the outer cylinder portion 144. Communicate with.

Here, the lid member 139 has a mirror-symmetrical shape with reference to a plane that passes through the central position in the axial direction and is orthogonal to the axial direction. In other words, the lid member 139 has a shape that does not distinguish between the front and back sides and does not cause erroneous assembly due to a mistake on the front and back sides. Further, by arranging the groove 264 for forming the passage portion on the outer peripheral portion of the lid member 139, the lid member 139 can be formed by sintering including the groove 264, and is sintered. ..

As described above, the seal portion 158 of the partition disk 134 contacts the inner peripheral surface of the outer cylinder portion 144 of the case member 131 over the entire circumference to seal the gap between the partition disk 134 and the outer cylinder portion 144. That is, the partition disk 134 is a packing valve. The seal portion 158 constantly seals the gap between the compartment disc 134 and the outer cylinder portion 144 even if the partition disk 134 is displaced and deformed within the allowable range in the frequency sensitive portion case 140. The partition disk 134 is centered on the frequency-sensitive portion case 140 as described above by the sealing portion 158 coming into contact with the outer cylinder portion 144 over the entire circumference. In the state of being centered in this way, the partition disk 134 seals the gap between the disk 155 and the disk 135 by bringing the inner peripheral portion into contact with the disk 135 over the entire circumference.

The partition disk 134 has a case chamber 171 (variable chamber) having a variable capacity on the bottom 141 side and a case chamber 172 (variable chamber) having a variable capacity on the lid member 139 side in the case member 131 of the frequency sensitive portion case 140. Two rooms are defined. In other words, the two case chambers 171, 172 are defined by the partition disk 134 composed of the disk 155 and the elastic sealing member 156, and are provided in the case member 131 of the frequency sensitive portion case 140. The case chamber 171 always communicates with the passage portion in the large diameter hole portion 146 of the case member 131 via the passage portion in the flow path groove 148 of the case member 131, and the case chamber 172 is in the groove 264 of the lid member 139. It always communicates with the lower chamber 20 via the passage portion.

The passage portion in the notch 87 of the disk 51 shown in FIG. 3, the passage portion in the large diameter hole portion 202 of the piston 18, the passage portion in the passage groove 30 of the piston rod 21, and the large diameter hole of the pilot case member 55. The passage portion in the portion 76, the passage portion in the flow path groove 81 of the pilot case member 55, the passage portion in the large-diameter hole portion 146 of the case member 131 shown in FIG. 4, and the passage portion 148 of the case member 131. The passage portion in the passage hole 37 of the piston 18, the back pressure chamber 80, and the case chamber 171 are always communicated with each other via the passage portion inside. The passage portion in the groove 264 formed between the lid member 139 and the outer tubular portion 144 of the case member 131 always communicates with the case chamber 172 and also communicates with the lower chamber 20 at all times.

The passage portion in the passage hole 37 of the piston 18 shown in FIG. 3, the passage portion in the notch 87 of the disk 51, the passage portion in the large diameter hole portion 202 of the piston 18, and the passage portion 30 in the passage groove 30 of the piston rod 21. The passage portion, the passage portion in the large-diameter hole portion 146 of the case member 131 shown in FIG. 4, the passage portion in the flow path groove 148 of the case member 131, the case chambers 171 and 172 in the case member 131, and the lid. The passage portion in the groove 264 of the member 139 constitutes a passage 107 (second passage) extending connecting the upper chamber 19 and the lower chamber 20. Therefore, in the cylindrical case member 131 having the case chambers 171 and 172 inside, the case chambers 171 and 172 which are at least a part of the passage 107 are formed inside. The passage 107 connects the upper chamber 19 and the lower chamber 20 by a route partially different from the passages 101 and 103.

In the passage 107, the passage portion in the passage hole 37 on the upper chamber 19 side shown in FIG. 2 is common to the passage 101, and the lower chamber 20 side of the passage portion in the passage hole 37 is provided in parallel with the passage 101. .. That is, in the passage 107, the passage portion in the notch 87 of the disk 51 shown in FIG. 3, the passage portion in the large-diameter hole portion 202 of the piston 18, the passage portion in the passage groove 30 of the piston rod 21, and FIG. In the passage portion in the large-diameter hole portion 146 of the case member 131, the passage portion in the flow path groove 148 of the case member 131, the case chambers 171 and 172 in the case member 131, and the groove 264 of the lid member 139. The passage portion is a parallel passage 109 parallel to the passage connecting the valve seat portion 47 and the main valve 231 of the passage 101 and the passage portion 88. The passage portion in the notch 87 of the disk 51 is an orifice which is a throttle in the passages 103 and 107.

The frequency-sensitive section 43 has a frequency-sensitive section case 140 provided in the parallel passage 109 of the passage 107. Therefore, in the frequency-sensitive portion case 140, two case chambers 171 and 172, which are a part of the parallel passage 109, are defined and provided by the partition disk 134 inside the case 140.

The partition disk 134 can be displaced and deformed within a range in which the inner peripheral side moves between the protruding portion 142 of the case member 131 and the disk 135 and the outer peripheral side moves between the support portion 143 and the flange portion 262 of the lid member 139. It has become. Here, the shortest axial direction between the support portion 143 that supports the axial intermediate portion of the disk 155 of the partition disk 134 from one side in the axial direction and the disk 135 that supports the inner peripheral side of the disk 155 from the other side in the axial direction. The distance is smaller than the axial thickness of the disc 155. Therefore, when the case chambers 171 and 172 have the same pressure, the disc 155 is pressed against the support portion 143 and the disc 135 with its own elastic force in a slightly deformed state.

The partition disk 134 blocks the flow of oil liquid between the case chambers 171 and 172 of the parallel passage 109 in a state where the inner peripheral side of the disk 155 is in contact with the disk 135 over the entire circumference. Further, the partition disk 134 allows oil liquid to flow between the case chamber 171 and the case chamber 172, that is, the lower chamber 20 in a state where the inner peripheral side of the disk 155 is separated from the disk 135. Therefore, the inner peripheral side of the disk 155 of the partition disk 134 and the disk 135 as the seat portion regulate the flow of the oil liquid from the case chamber 171 to the case chamber 172 and the lower chamber 20 in the parallel passage 109, while lowering. A check valve 245 that allows the flow of oil liquid from the chamber 20 and the case chamber 172 to the case chamber 171 is configured.

The check valve 245 is in parallel so that the upper chamber 19 and the lower chamber 20 can communicate with each other via the passage portion in the passage hole 37 of the piston 18 in the extension stroke in which the pressure on the upper chamber 19 side becomes higher than the pressure of the lower chamber 20. While the communication of the passage 109 is cut off, the parallel passage 109 is in the communication state in the contraction stroke in which the pressure on the upper chamber 19 side becomes lower than the pressure of the lower chamber 20.

The check valve 245 is a free valve in which the entire partition disk 134, which is a valve body thereof, can move in the axial direction. The partition disk 134 is set so that the entire inner circumference of the disk 155 is always in contact with the disk 135 regardless of the pressure state of the case chambers 171 and 172, and the case chamber 171 of the parallel passage 109 is set. , The distribution between 172 may be cut off at all times. That is, the disk 155 of the partition disk 134 may block the flow of the oil liquid in at least one direction, including the flow in both directions between the case chamber 171 and the case chamber 172 of the passage 107.

In the piston rod 21, the annular member 120, the disc 119, the disc 118, the plurality of discs 117, the disc 116, with the mounting shaft portion 28 inserted inside the shaft step portion 29 shown in FIG. A plurality of discs 115, a plurality of discs 113, a disc 112, a disc 111, a disc 110, a piston 18, a disc 51 shown in FIG. 3, a disc 210, a disc 211, a disc 212, a plurality of discs 213, a pilot valve 52, Piston case member 55, disc 56 shown in FIG. 4, a plurality of discs 57, a plurality of discs 58, a plurality of discs 59, a plurality of discs 60, a disc 61, a disc 62, a case member 131, and a plurality of discs. 133 are stacked in this order. At this time, in the pilot case member 55 shown in FIG. 3, the seal member 86 of the pilot valve 52 is fitted to the outer cylinder portion 73.

Further, the partition disk 134 is stacked on the support portion 143 of the case member 131 with the disk 133 shown in FIG. 4 inserted inside. At this time, the elastic sealing member 156 of the partition disk 134 is fitted to the outer cylinder portion 144 of the case member 131. Further, the disk 135 is superposed on the disk 133 and the disk 155 of the partition disk 134 with the mounting shaft portion 28 inserted inside each of them. Further, with the mounting shaft portion 28 inserted inward, the disc 136 is stacked on the disc 135, and the lid member 139 is stacked on the disc 136. At this time, the lid member 139 is inserted into the outer tubular portion 144 of the case member 131.

With the parts arranged in this way, the nut 176 is screwed into the male screw 31 of the mounting shaft portion 28 protruding from the lid member 139. As a result, the laminated members from the annular member 120 shown in FIG. 2 to the lid member 139 shown in FIG. 4 are clamped by the shaft step portion 29 of the piston rod 21 and the nut 176, respectively, on the inner peripheral side or the entire shaft. Clamped in the direction. At that time, the partition disk 134 is supported by the support portion 143 and the disk 135 without being clamped on the inner peripheral side in the axial direction. At that time, the clamp seat portion 501 of the piston body 35 shown in FIG. 3 and the clamp seat portion 511 of the inner cylinder portion 72 of the pilot case member 55 are main composed of disks 51, 210 to 213 and a pilot valve 52. The inner peripheral side of the valve 231 is clamped by sandwiching it in the axial direction. The nut 176 shown in FIG. 4 is a general-purpose hexagonal crimping nut, which is fastened to the piston rod 21 with a predetermined torque and then crimped to prevent rotation.

As a result, the compression side damping force generation mechanism 42 shown in FIG. 2, the piston 18, the extension side damping force generation mechanism 41 shown in FIG. 3, and the extension side damping force generation mechanism 105 shown in FIG. 4 are extended. The frequency sensitive portion 43 on the side is fastened to the piston rod 21 by a nut 176 with the piston rod 21 inserted on the inner peripheral side of each. Further, the frequency sensitive portion 43 has a case member 131, a plurality of discs 133, a disc 135, a disc 136, and a lid member 139, and the piston rod 21 is inserted in the inner peripheral side of the case member 131. Is fastened with a nut 176.

As shown in FIG. 1, the above-mentioned base valve 25 is provided between the cylinder bottom 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, that is, a lower side of the base valve member 191. It has a disc 193 provided on the chamber 20 side, and a mounting pin 194 for mounting the disc 192 and the disc 193 to the base valve member 191.

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

The disk 192 and the base valve member 191 form a compression valve 197 on the contraction side, which is opened in the contraction stroke of the shock absorber 1 to allow oil and liquid to flow from the lower chamber 20 to the reservoir chamber 6 and generate a damping force. There is. The disk 193, together with the base valve member 191, constitutes a suction valve 198 that opens in the extension stroke of the shock absorber 1 and allows oil liquid to flow from the reservoir chamber 6 into the lower chamber 20. The suction valve 198 has a function of flowing a liquid from the reservoir chamber 6 to the lower chamber 20 without substantially generating a damping force so as to make up for the shortage of the liquid mainly caused by the extension of the piston rod 21 from the cylinder 2. Fulfill.

In the shock absorber 1 of the first embodiment, in the extension stroke in which the piston rod 21 moves to the extension side, the oil liquid flows from the upper chamber 19 toward the lower chamber 20 through the passage portion in the passage hole 37 of the piston 18. .. The flow of oil liquid from the upper chamber 19 through the passage portion in the passage hole 37 in this extension stroke includes the valve seat portion 47 of the piston 18 and the fixed orifice 227 from the passage portion in the passage hole 37. There is a flow path that flows to the lower chamber 20 through the damping force generation mechanism 41 having the main valve 231 and the passage portion 88 between the piston 18 and the case member 55. This is a passage through the passage 101.

Further, in parallel with the above, the flow of the oil liquid from the upper chamber 19 through the passage portion in the passage hole 37 in the extension stroke is performed from the passage portion in the passage hole 37 to the inside of the notch 87 in the disk 51. In the passage portion of the case member 55, the passage portion in the large diameter hole portion 202, the passage portion in the passage groove 30, the passage portion in the large diameter hole portion 76, and the passage portion in the protrusion 78 of the case member 55. There is a flow path that flows from the passage portion to the back pressure chamber 80 for the main valve 231 and flows to the lower chamber 20 through the damping force generation mechanism 105 including the valve seat portion 79 of the case member 55 and the sub valve 99. This is a passage through the passage 103.

At the time of low frequency input (large amplitude input) to the shock absorber 1, from the upper chamber 19, the passage portion in the passage hole 37, the passage portion in the notch 87, the passage portion in the large diameter hole portion 202, and the passage groove 30. The amount of oil flowing to the case chamber 171 of the frequency sensitive portion 43 through the passage portion, the passage portion in the large-diameter hole portion 146, and the passage portion in the flow path groove 148 is large, and the amount of bending of the partition disk 134 is also large. The partition disk 134 abuts on the flange portion 262 of the lid member 139 at the stopper portion 159 and is deformed until the bending is restricted.

In the state where the bending of the partition disk 134 is regulated by the lid member 139, the oil liquid from the upper chamber 19 is supplied to the passage portion in the passage hole 37, the passage portion in the notch 87, and the large diameter hole portion 202. It flows into the back pressure chamber 80 through the passage portion, the passage portion in the passage groove 30, the passage portion in the large diameter hole portion 76, and the passage portion in the flow path groove 81. Then, the pressure in the back pressure chamber 80 rises to a high pressure, and the valve opening pressure of the main valve 231 of the damping force generation mechanism 41 rises. Therefore, as shown in FIGS. 6 to X3, the damping force has a hard characteristic.

At the time of this low frequency input, in the very low speed region where the piston speed is very low, the oil liquid that has entered the passage portion in the passage hole 37 from the upper chamber 19 is the main valve in the valve closed state of the damping force generation mechanism 41. It flows through the fixed orifice 227 of 231 and flows to the lower chamber 20 through the passage portion 88 between the piston 18 and the case member 55. Therefore, the characteristic of the damping force with respect to the piston speed becomes the orifice characteristic, and as shown by X1 in FIG. 6, the rate of increase of the damping force is relatively high with respect to the increase of the piston speed.

From this state, when the piston speed is increased and the flow rate flowing through the passage portion in the passage hole 37 of the piston 18 is increased, the oil liquid from the upper chamber 19 is the main of the damping force generation mechanism 41 at a predetermined piston speed. The valve 231 is separated from the valve seat portion 47, that is, the valve is opened, and flows to the lower chamber 20 through the passage portion 88 between the piston 18 and the case member 55. Therefore, the characteristic of the damping force with respect to the piston speed is a valve characteristic, and therefore, as shown by X3 in FIG. 6, the rate of increase of the damping force is relatively low with respect to the increase of the piston speed.

When the valve is opened at the time of this low frequency input, the main valve 231 has the shortest support length of the holding seat portion 511 of the pilot case member 55, in other words, the length of the portion not supported by the holding seat portion 511 is the longest and is rigid. The lower side first separates from the valve seat portion 47, gradually separates from the valve seat portion 47 toward the side where the support length of the holding seat portion 511 is the longest, and finally the support length of the holding seat portion 511. The side with the longest length, in other words, the side with the shortest length and the highest rigidity of the portion not supported by the holding seat portion 511, is separated from the valve seat portion 47.

That is, the main valve 231 is separated from the valve seat portion 47 on the shortest separation portion 515 side in the circumferential direction of the holding seat portion 511 of the pilot case member 55, and gradually from the valve seat portion 47 toward the longest separation portion 516 side. After leaving the seat, the longest distance portion 516 side finally separates from the valve seat portion 47, and the entire seat is separated. As a result, the damping force generating mechanism 41 opens the valve while gradually increasing the valve opening amount without opening the valve at once. As a result, the transient characteristic of the damping force when the characteristic is switched from the orifice characteristic shown by X1 in FIG. 6 to the valve characteristic shown by X3 can be smoothly changed as shown by X2 in FIG.

When the piston speed is further increased, the oil liquid flowing from the upper chamber 19 into the passage portion in the passage hole 37 generates a damping force which is a hard valve in addition to the flow of the damping force generation mechanism 41 which opens the valve as described above. The mechanism 105 is opened and flows to the lower chamber 20. Therefore, the rate of increase in damping force becomes lower with respect to the increase in piston speed.

At the time of high frequency input (small amplitude input) to the shock absorber 1, from the upper chamber 19, the passage portion in the passage hole 37, the passage portion in the notch 87, the passage portion in the large diameter hole portion 202, and the passage groove 30. The amount of oil flowing to the case chamber 171 via the passage portion, the passage portion in the large-diameter hole portion 146, and the passage portion in the flow path groove 148 is small, the amount of bending of the partition disk 134 is also small, and the stopper is attached to the lid member 139. Even if it comes into contact with the portion 159, it deforms within a range in which the bending is not regulated. Therefore, since the inflow of the oil liquid into the case chamber 171 can be absorbed by the bending of the partition disk 134, the pressure of the back pressure chamber 80 that always communicates with the case chamber 171 does not rise and becomes a low pressure, and the main valve of the damping force generation mechanism 41 The valve opening pressure of 231 is low. Therefore, as shown in FIGS. 6 to X6, the damping force has a soft characteristic.

At the time of this high frequency input, as in the low frequency input, in the very low speed region where the piston speed is very low, the oil liquid that has entered the passage portion in the passage hole 37 from the upper chamber 19 closes the damping force generation mechanism 41. It flows through the fixed orifice 227 of the main valve 231 in the valve state, and flows into the lower chamber 20 through the passage portion 88 between the piston 18 and the case member 55. Therefore, the characteristic of the damping force with respect to the piston speed is the orifice characteristic, and as shown by X4 in FIG. 6, the rate of increase of the damping force is relatively high with respect to the increase of the piston speed.

From this state, when the piston speed is increased and the flow rate flowing through the passage portion in the passage hole 37 of the piston 18 is increased, the oil liquid flowing from the upper chamber 19 into the passage portion in the passage hole 37 at a predetermined piston speed. Allows the main valve 231 of the damping force generation mechanism 41 to be separated from the valve seat portion 47, that is, opened, and flows into the lower chamber 20 via the passage portion 88 between the piston 18 and the case member 55. Therefore, the characteristic of the damping force with respect to the piston speed is a valve characteristic, and as shown by X6 in FIG. 6, the rate of increase of the damping force is relatively low with respect to the increase of the piston speed.

Even when the valve is opened at the time of this high frequency input, the main valve 231 first separates from the valve seat portion 47 on the side where the support length of the pinch seat portion 511 of the pilot case member 55 is the shortest, and the support length of the pinch seat portion 511. The side with the longest support length gradually separates from the valve seat portion 47, and finally, the side with the longest support length of the holding seat portion 511 leaves the valve seat portion 47. As a result, the damping force generating mechanism 41 opens the valve while gradually increasing the valve opening amount without opening the valve at once. As a result, the transient characteristic of the damping force when the characteristic is switched from the orifice characteristic indicated by X4 to the valve characteristic indicated by X6 can be smoothed as shown by X5.

When the piston speed is further increased, the oil liquid flowing from the upper chamber 19 into the passage portion in the passage hole 37 generates a damping force which is a hard valve in addition to the flow of the damping force generation mechanism 41 which opens the valve as described above. The mechanism 105 is opened and flows to the lower chamber 20. Therefore, the rate of increase in damping force becomes lower with respect to the increase in piston speed.

In the contraction stroke in which the piston rod 21 moves to the contraction side, when the piston speed is slow, the oil liquid from the lower chamber 20 flows into the passage portion in the passage hole 39 on the contraction side shown in FIG. 2 and the damping force generation mechanism 42. It flows to the upper chamber 19 through the fixed orifice 127 of the disc valve 129, and the damping force of the orifice characteristic is generated. Therefore, as for the characteristics of the damping force with respect to the piston speed, as shown by X7 in FIG. 6, the rate of increase in the damping force is relatively high with respect to the increase in the piston speed.

Further, when the piston speed becomes high, the oil liquid introduced from the lower chamber 20 into the passage portion in the passage hole 39 on the contraction side basically opens the disc valve 129 of the damping force generation mechanism 42 while opening the disc valve 129 and the valve. It will flow to the upper chamber 19 through the space between the seat portion 49 and the damping force of the valve characteristic. Therefore, as for the characteristics of the damping force with respect to the piston speed, as shown by X8 in FIG. 6, the rate of increase of the damping force decreases with respect to the increase of the piston speed.

Here, in the frequency sensitive portion 43, the pressure in the lower chamber 20 becomes higher during the contraction stroke, and the pressure in the case chamber 172 becomes higher than the pressure in the case chamber 171. As a result, the disk 155 of the partition disk 134 as the valve body of the check valve 245 is deformed with the support portion 143 of the case member 131 as a fulcrum, and is separated from the disk 135 as the valve seat of the check valve 245. As a result, the check valve 245 opens the passage 107 including the passage portion in the flow path groove 148, and the oil liquid flows from the lower chamber 20 toward the upper chamber 19. At that time, the partition disk 134 is separated from the disk 135 to eliminate the differential pressure, and further movement is suppressed.

The shock absorber of Patent Document 1 described above includes a main valve that controls the flow of oil liquid from the upstream chamber to the downstream chamber caused by sliding of the piston to generate a damping force, and a closed valve of the main valve. It has a back pressure chamber that acts back pressure in the direction. By the way, in the shock absorber, for example, if the characteristic change when the damping force characteristic is switched is large, there is a possibility that the riding comfort is lowered and an abnormal noise is generated. Therefore, in the shock absorber, it is required to smooth the damping force characteristic.

In the shock absorber 1 of the present embodiment, the damping force generation mechanism 41 on the extension side provides resistance to the flow of the working fluid from the upper chamber 19 on the upstream side of the passage 101 to the lower chamber 20 on the downstream side in the extension stroke. The main valve 231 to be provided, the outer cylinder portion 73 having an opening 77 at one end, the inner cylinder portion 72 into which the piston rod 21 is inserted, and the bottom portion 71, and the main valve 231 arranged on the opening 77 side is the inner cylinder. A bottomed tubular pilot case member 55 that is supported by the holding seat portion 511 of the portion 72 and forms an internal pressure chamber 80 in which an internal pressure is applied in the valve closing direction of the main valve 231 and an upstream side to the back pressure chamber 80. It has a back pressure introduction passage 235 for introducing the working fluid from the upper chamber 19.

In the damping force generation mechanism 41 having such a structure, the damping force generation mechanism 41 is formed because the radial width of the holding seat portion 511 of the inner cylinder portion 72 supporting the main valve 231 is formed non-uniformly in the circumferential direction. , The valve will be opened while gradually increasing the valve opening amount without opening the valve at once. Therefore, it is possible to smooth the transient characteristic of the damping force when the characteristic is switched from the orifice characteristic to the valve characteristic. As a result, it is possible to suppress deterioration of riding comfort and generation of abnormal noise.

Further, since the sandwiching sheet portion 511 of the pilot case member 55, which is an integrally molded product, is formed so that the radial width is non-uniform in the circumferential direction, a separate disk having a non-uniform radial width in the circumferential direction is unnecessary. become. Therefore, the number of parts can be reduced and the cost can be reduced.

Further, since the main valve 231 is directly supported by the holding seat portion 511 of the pilot case member 55 which is an integrally molded product, the number of parts can be further reduced and the cost can be further reduced.

Further, since the outer shape of the holding sheet portion 511 is eccentric with respect to the central axis of the pilot case member 55, the radial width of the holding sheet portion 511 is made non-uniform in the circumferential direction, so that the damping force generation mechanism 41 is provided. The valve can be opened more smoothly. Therefore, the transient characteristic of the damping force when the characteristic is switched from the orifice characteristic to the valve characteristic can be further smoothed.

Further, since the outer shape of the holding seat portion 511 is eccentric with respect to the central axis of the pilot case member 55, it is possible to alleviate the stress concentration generated on the disk 85 of the pilot valve 52 that abuts on the holding seat portion 511. .. Therefore, the durability of the main valve 231 including the pilot valve 52 can be improved.

Here, when a separate disc having a non-uniform radial width is used, the disc having a non-uniform radial width is arranged at a position between the plurality of discs 213 constituting the main valve 231. Become. In such a case, the rigidity of the portion between the disc and the valve seat portion 47 of the main valve 231 becomes low. Then, when the frequency sensitive portion 43 is provided, the main valve 231 may vibrate or unnecessarily leave the valve seat portion 47 when the partition disk 134 expands the capacity of the case chamber 171. There is. If the main valve 231 vibrates or is unnecessarily separated from the valve seat portion 47, the damping force waveform is disturbed, which may reduce the riding comfort and generate abnormal noise.

On the other hand, in the present embodiment, since the holding sheet portion 511 of the pilot case member 55, which is an integrally molded product, is formed so that the radial width is non-uniform in the circumferential direction, the radial width is not uniform in the circumferential direction. Eliminates the need for a separate uniform disc. Therefore, since it is possible to suppress the decrease in the rigidity of the main valve 231, it is possible to suppress the vibration generated in the main valve 231 when the partition disk 134 expands the capacity of the case chamber 171, and the main valve 231 is unnecessarily a valve seat. It is possible to suppress leaving the seat 47. As a result, it is possible to suppress the disturbance of the damping force waveform, the deterioration of the riding comfort, and the generation of abnormal noise.

By applying the above configuration to the damping force generating mechanism 41 among the damping force generating mechanisms 41 and 105, which has a large influence on the deterioration of the riding comfort and the generation of abnormal noise, the riding comfort is effectively reduced and the abnormal noise is generated. Can be suppressed.

[Second Embodiment]
Next, the second embodiment will be described mainly based on FIG. 7, focusing on the differences from the first embodiment. The parts common to the first embodiment are represented by the same name and the same reference numerals.

In the second embodiment, the shape of the holding sheet portion 511A of the inner cylinder portion 72 of the pilot case member 55 is different from that of the holding sheet portion 511 of the first embodiment. The sandwiched seat portion 511A of the second embodiment has a plurality of, specifically three locations, in which the outer shape of the sandwiched seat surface 512A, that is, the outer peripheral edge portion 513A is arranged at equidistant positions from the center of the pilot case member 55. It is composed of a linear portion 531 and a plurality of, specifically, three arc-shaped portions 532 arranged at equidistant positions from the center of the pilot case member 55.

The plurality of linear portions 531 are straight lines having the same length, and all of them are orthogonal to the radial direction of the pilot case member 55. The plurality of linear portions 531 are arranged at equal intervals in the circumferential direction of the pilot case member 55, and are arranged at the same angle, specifically, with a deviation of 120 degrees.

The plurality of arc-shaped portions 532 are arcs having the same length and the same curvature, and all of them are curved so as to be centered on the central axis side of the pilot case member 55. The plurality of arcuate portions 532 are arranged at equal intervals in the circumferential direction of the pilot case member 55, and are arranged at the same angle, specifically, with a deviation of 120 degrees. The linear portion 531 and the arc-shaped portion 532 are alternately arranged in the circumferential direction of the pilot case member 55. The plurality of arcuate portions 532 continuously connect linear portions 531 adjacent to each other on both sides.

The sandwiching sheet surface 512A has a constant inner diameter over the entire circumference, in other words, the inner peripheral edge portion 514 thereof has a circular shape with a constant diameter. Therefore, also in the second embodiment, the radial width of the sandwiched seat portion 512A, which is the width of the pilot case member 55 in the radial direction, is not constant over the entire circumference and is non-uniform in the circumferential direction. It is formed to be.

The outer peripheral edge portion 513A of the sandwiching sheet surface 512A has a plurality of circles in which the center of each of the plurality of linear portions 531 in the length direction is the shortest separation portion 515A in which the distance from the central axis of the pilot case member 55 is the minimum. The center of each of the arcuate portions 532 in the circumferential direction is the longest separation portion 516A at which the distance from the central axis of the pilot case member 55 is maximum. In the outer peripheral edge portion 513A, the shortest separation portion 515A is provided at a plurality of, specifically, three locations, and the longest separation portion 516A is also provided at a plurality of, specifically, three locations.

The distance of the outer peripheral edge portion 513A from the central axis of the pilot case member 55 increases as the distance from the shortest separation portion 515A toward the longest separation portion 516A adjacent to each other in the circumferential direction of the pilot case member 55. In other words, the radial width of the sandwiched seat surface 512A is the narrowest at the position of the shortest separation portion 515A, and widens toward the adjacent longest separation portion 516A in the circumferential direction of the pilot case member 55, and the longest separation portion 516A. Widest in position.

Here, the distance of the shortest separation portion 515A from the central axis of the pilot case member 55 is substantially equal to the radius of the outer peripheral portion of the disk 210 and the radius of the outer peripheral edge portion 503 of the sandwiched seat surface 502 of the piston 18. Therefore, the distance from the central axis of the pilot case member 55 of the longest separation portion 516A is larger than the radius of the outer peripheral portion of the disk 210 and the radius of the outer peripheral edge portion 503 of the sandwiched seat surface 502 of the piston 18.

In the pilot valve 52, the minimum radius of the seal member 86 is longer than the distance from the central axis of the pilot case member 55 to the longest separation portion 516A of the sandwiched seat surface 512A, and the inner peripheral side of the disk 85 is a pilot. It comes into contact with the holding sheet surface 512A of the inner cylinder portion 72 of the case member 55 by surface contact. In other words, the pilot case member 55 directly supports the pilot valve 52 arranged on the opening 77 side of the outer cylinder portion 73 by the holding seat portion 511A of the inner cylinder portion 72.

The holding seat portion 511A has the shortest support length for supporting the pilot valve 52 in the radial direction of the pilot case member 55 at the position of the shortest separation portion 515A in the circumferential direction of the pilot case member 55, and the pilot from the shortest separation portion 515A. It becomes longer toward the adjacent longest separation portion 516A in the circumferential direction of the case member 55, and becomes the longest at the position of the longest separation portion 516A. In other words, the length of the portion of the pilot valve 52 that is not supported by the holding seat portion 511A in the radial direction becomes the longest at the position of the shortest separation portion 515A in the circumferential direction of the pilot case member 55, and the pilot is piloted from the shortest separation portion 515A. It becomes shorter toward the adjacent longest separation portion 516A in the circumferential direction of the case member 55, and becomes the shortest at the position of the longest separation portion 516A.

In the shock absorber 1 of the second embodiment, when the damping force generating mechanism 41 is opened in the extension stroke in which the piston rod 21 moves to the extension side, the main valve 231 has the support length of the holding seat portion 511A of the pilot case member 55. The side with the shortest length, in other words, the side with the longest length of the part not supported by the holding seat part 511A and the side with the lowest rigidity first separates from the valve seat part 47, and the side with the longest supporting length of the holding seat part 511A The valve is gradually separated from the valve seat portion 47 toward the valve, and finally, the side having the longest support length of the holding seat portion 511A, in other words, the side having the shortest length of the portion not supported by the holding seat portion 511A and having the highest rigidity is the valve. Leave the seat 47.

That is, the main valve 231 is separated from the valve seat portion 47 from the side of the shortest separation portion 515A at a plurality of locations in the circumferential direction of the holding seat portion 511A of the pilot case member 55, and is the longest adjacent to each other in the circumferential direction of the pilot case member 55. The seat is gradually separated from the valve seat portion 47 toward the separation portion 516A side, and finally the longest separation portion 516A side at a plurality of locations is separated from the valve seat portion 47. As a result, the damping force generating mechanism 41 opens the valve while gradually increasing the valve opening amount without opening the valve at once. As a result, as in the first embodiment, the transient characteristic of the damping force when the characteristic is switched from the orifice characteristic to the valve characteristic can be smoothly changed. Therefore, the same effect as that of the first embodiment can be obtained.

Further, since the outer shape of the holding sheet surface 512A of the holding sheet portion 511A, that is, the outer peripheral edge portion 513A has the same shape at equal intervals in the circumferential direction of the pilot case member 55, the linear portion 531 and the arc-shaped portion 532 are each three. If the outer peripheral edge portion 513A has a substantially regular polygonal shape, the main valve 231 can be similarly opened at equidistant positions in the circumferential direction of the pilot case member 55. Therefore, in the passage 101, the working fluid can be caused to flow out to the lower chamber 20 radially with reference to the center of the piston 18 during the valve opening of the damping force generation mechanism 41. If the linear portion 531 and the arc-shaped portion 532 are each provided at two locations and the outer peripheral edge portion 513A is formed into a substantially oval shape, the working fluid is symmetrically transferred to the lower chamber 20 during the valve opening of the damping force generation mechanism 41. It can be leaked.

[Third Embodiment]
Next, the third embodiment will be described mainly based on FIG. 8, focusing on the differences from the first embodiment. The parts common to the first embodiment are represented by the same name and the same reference numerals.

In the third embodiment, the shape of the holding sheet portion 511B of the inner cylinder portion 72 of the pilot case member 55 is different from that of the holding sheet portion 511 of the first embodiment. The sandwiched sheet portion 511B of the third embodiment has an elliptical shape in the outer shape of the sandwiched sheet surface 512B, that is, the outer peripheral edge portion 513B.

The sandwiching sheet surface 512B has a constant inner diameter over the entire circumference, in other words, the inner peripheral edge portion 514 thereof has a circular shape with a constant diameter. The elliptical outer peripheral edge portion 513B and the circular inner peripheral edge portion 514 are arranged concentrically with their centers aligned. Therefore, also in the third embodiment, the radial width of the sandwiched seat portion 512B, which is the width of the pilot case member 55 in the radial direction, is not constant over the entire circumference and is non-uniform in the circumferential direction. It is formed to be.

The elliptical outer peripheral edge portion 513B of the sandwiching sheet surface 512B has a position where the short axis intersects the shortest separation portion 515B where the distance from the central axis of the pilot case member 55 is the minimum, and the position where the long axis intersects. It is the longest separation portion 516B at which the distance from the central axis of the pilot case member 55 is maximum. In the outer peripheral edge portion 513B, the shortest separation portion 515B is provided at two locations, and the longest separation portion 516B is also provided at two locations.

The distance of the outer peripheral edge portion 513B from the central axis of the pilot case member 55 increases as the distance from the shortest separation portion 515B toward the longest separation portion 516B adjacent to each other in the circumferential direction of the pilot case member 55. In other words, the radial width of the sandwiched seat surface 512B is the narrowest at the position of the shortest separation portion 515B, and widens toward the adjacent longest separation portion 516B in the circumferential direction of the pilot case member 55, and the longest separation portion 516B. Widest in position.

Here, the distance of the shortest separation portion 515B from the central axis of the pilot case member 55 is substantially equal to the radius of the outer peripheral portion of the disk 210 and the radius of the outer peripheral edge portion 503 of the sandwiched seat surface 502 of the piston 18. Therefore, the distance of the longest separation portion 516B from the central axis of the pilot case member 55 is larger than the radius of the outer peripheral portion of the disk 210 and the radius of the outer peripheral edge portion 503 of the sandwiched seat surface 502 of the piston 18.

In the pilot valve 52, the minimum radius of the seal member 86 is longer than the distance from the central axis of the pilot case member 55 to the longest separation portion 516B of the sandwiched seat surface 512B, and the inner peripheral side of the disk 85 is the pilot case. The inner cylinder portion 72 of the member 55 abuts on the holding sheet surface 512B by surface contact. In other words, the pilot case member 55 directly supports the pilot valve 52 arranged on the opening 77 side of the outer cylinder portion 73 by the holding seat portion 511B of the inner cylinder portion 72.

The holding seat portion 511B has the shortest support length for supporting the pilot valve 52 in the radial direction of the pilot case member 55 at the position of the shortest separation portion 515B in the circumferential direction of the pilot case member 55, and is piloted from the shortest separation portion 515B. It becomes longer toward the adjacent longest separation portion 516B in the circumferential direction of the case member 55, and becomes the longest at the position of the longest separation portion 516B. In other words, the length of the portion of the pilot valve 52 that is not supported by the holding seat portion 511B in the radial direction becomes the longest at the position of the shortest separation portion 515B in the circumferential direction of the pilot case member 55, and the pilot is piloted from the shortest separation portion 515B. It becomes shorter toward the adjacent longest separation portion 516B in the circumferential direction of the case member 55, and becomes the shortest at the position of the longest separation portion 516B.

In the shock absorber 1 of the third embodiment, when the damping force generating mechanism 41 is opened in the extension stroke in which the piston rod 21 moves to the extension side, the main valve 231 is the support length of the holding seat portion 511B of the pilot case member 55. The side with the shortest length, in other words, the side with the longest length of the part not supported by the holding seat part 511B and the side with the lowest rigidity first separates from the valve seat part 47, and the side with the longest supporting length of the holding seat part 511B The valve is gradually separated from the valve seat portion 47 toward the valve, and finally, the side having the longest support length of the holding seat portion 511B, in other words, the side having the shortest length of the portion not supported by the holding seat portion 511B and having the highest rigidity is the valve. Leave the seat 47.

That is, the main valve 231 is separated from the valve seat portion 47 from the two shortest separation portions 515B side in the circumferential direction of the holding seat portion 511B of the pilot case member 55, and is the longest adjacent to each other in the circumferential direction of the pilot case member 55. The seat is gradually separated from the valve seat portion 47 toward the separation portion 516B side, and finally the two longest separation portions 516B side are separated from the valve seat portion 47. As a result, the damping force generating mechanism 41 opens the valve while gradually increasing the valve opening amount without opening the valve at once. Thereby, as in the first embodiment, the transient characteristic of the damping force when the characteristic is switched from the orifice characteristic to the valve characteristic can be smoothly changed. Therefore, the same effect as that of the first embodiment can be obtained.

Further, since the outer shape of the holding seat surface 512B of the holding seat portion 511B is elliptical, the main valve 231 can be opened symmetrically from different positions by 180 degrees. Therefore, in the passage 101, the working fluid can flow out to the lower chamber 20 symmetrically with respect to the center of the piston 18 during the valve opening of the damping force generation mechanism 41.

In the first to third embodiments, the frequency sensitive unit 43C shown in FIG. 9 may be used instead of the frequency sensitive unit 43. The frequency-sensitive portion 43C has a lid member 131C having a shape in which the outer tubular portion 144 and the protruding portion 142 of the case member 131 are eliminated. The lid member 131C has a support portion 143, a small diameter hole portion 145, a large diameter hole portion 146, and a flow path groove 203. Further, the frequency sensitive portion 43C has a cylindrical case member 139C (housing member). The case member 139C has a bottomed tubular shape having a flat plate-shaped bottom portion 401 having a through hole 400 and a cylindrical cylindrical portion 402 extending in the axial direction from the outer peripheral edge portion of the bottom portion 401. The passage portion in the through hole 400 constitutes a part of the passage 107 described above. The lid member 131C is fitted to the cylindrical portion 402 of the case member 139C, thereby forming the frequency sensitive portion case 140C. The mounting shaft portion 28 of the piston rod 21 is inserted into the frequency sensitive portion case 140C. As a result, the mounting shaft portion 28 is arranged in the case member 139C.

A large-diameter portion 405 is provided on the inner peripheral side of the cylindrical portion 402 of the case member 139C on the side opposite to the bottom portion 401, and a small-diameter portion 406 having an inner diameter smaller than that of the large-diameter portion 405 is provided on the bottom portion 401 side. A step portion 407 extending in the direction orthogonal to the axis is formed between the large diameter portion 405 and the small diameter portion 406.

In the frequency-sensitive unit 43C, the partition disk 134C (definition member) is also partially different from the frequency-sensitive unit 43. The partition disk 134C is arranged in the case member 139C. The partition disk 134C has an annular elastic sealing member 156C fixed to the inner peripheral side of the perforated disk-shaped flexible disk 155C. The outer peripheral side of the partition disk 134C is supported by the step portion 407 as the seat portion of the case member 139C, and the radial intermediate position of the disk 155C is supported by the support portion 143 of the lid member 131C. The axial dimension between the step portion 407 and the support portion 143 is smaller than the thickness of the disk 155C. As a result, a set load is applied to the partition disk 134C.

Inside the case member 139C, two case chambers 171C (variable chambers) and a case chamber 172C (variable chambers) are provided, which are defined by a compartmentalized disc 134C composed of a disc 155C and an elastic sealing member 156C. In other words, the compartment disk 134C defines two variable capacity case chambers 171C and case chambers 172C in the case member 139C. The case chambers 171C and 172C also form a part of the passage 107. In the partition disk 134C, the outer peripheral side of the disk 155C of the partition disk 134C and the step portion 407 of the frequency sensitive portion case 140C form an oil solution from the case chamber 171C to the case chamber 172C and the lower chamber 20 in the parallel passage 109 of the passage 107. A check valve 245C is configured to allow the flow of oil liquid from the lower chamber 20 and the case chamber 172C to the case chamber 171C while regulating the flow of the oil liquid.

The frequency-sensitive unit 43C having such a configuration also operates in the same manner as the frequency-sensitive unit 43, and makes the damping force variable in response to the piston frequency. That is, when the piston frequency is high, the partition disk 134C is deformed each time the extension stroke is performed, and the oil liquid is introduced into the case chamber 171C from the upper chamber 19. Further, when the piston frequency is low, the oil liquid flows from the upper chamber 19 to the case chamber 171C at the initial stage of the extension stroke, but after that, the partition disk 134C abuts on the case member 139C and stops, and the case from the upper chamber 19. The oil liquid does not flow into the chamber 171C.

The above embodiment shows an example in which the present invention is used for a double-cylinder hydraulic shock absorber, but the present invention is not limited to this, and the outer cylinder is eliminated and the lower chamber 20 in the cylinder 2 is on the opposite side to the upper chamber 19. It may be used for a monotube type hydraulic shock absorber that forms a gas chamber with a slidable compartment, and may be used for any shock absorber including a pressure control valve using a packing valve having a structure in which a sealing member is provided on a disk. Can be done. Of course, it is also possible to apply the present invention to the above-mentioned damping force generation mechanism 42 on the contraction side, or to apply the present invention to the above-mentioned base valve 25. It is also applicable when 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 the oil passage. Further, in the above embodiment, the hydraulic shock absorber is shown as an example, but water or air can also be used as the fluid.

In the first aspect of the embodiment described above, a cylinder in which a working fluid is enclosed, a piston that is slidably fitted in the cylinder and divides the inside of the cylinder into two chambers, and one end side thereof are described. A piston rod that is connected to a piston and whose other end extends to the outside of the cylinder, a first passage through which working fluid flows out from one chamber in the cylinder due to the movement of the piston, and the first passage. The damping force generating mechanism is provided with a damping force generating mechanism for generating a damping force, and the damping force generating mechanism provides a resistance force to the flow of the working fluid from the chamber on the upstream side to the chamber on the downstream side of the first passage. It consists of a valve, an outer cylinder having an opening at one end, an inner cylinder through which the piston rod is inserted, and a bottom, and the main valve arranged on the opening side is supported by the seat of the inner cylinder. A bottomed tubular case member that forms a back pressure chamber that applies internal pressure in the closing direction of the main valve, and a back pressure introduction passage that introduces working fluid into the back pressure chamber from the chamber on the upstream side. The sheet portion is formed so that the radial width becomes non-uniform in the circumferential direction. This makes it possible to smooth the damping force characteristics.

Further, in the second aspect, in the first aspect, the outer shape of the seat portion is eccentric with respect to the central axis of the case member.

Further, in the third aspect, in the first aspect, the outer shape of the sheet portion is elliptical.

Further, in the fourth aspect, in any one of the first to third aspects, a second passage provided in parallel with the first passage is provided, and at least a part of the second passage is formed inside. The frequency-sensitive portion includes a tubular housing member and a drawing member that defines two variable chambers in the housing member.

1 Shock absorber 2 Cylinder 18 Piston 19 Upper chamber (upstream chamber)
20 Lower room (downstream room)
21 Piston rod 41 Damping force generation mechanism 43,43C Frequency sensitive part 55 Pilot case member (case member)
71 Bottom 72 Inner cylinder 73 Outer cylinder 77 Opening 80 Back pressure chamber 101 Passage (1st passage)
107 passage (second passage)
131,139C Case member (housing member)
134, 134C compartment disk (drawing member)
171,172 Case room (variable room)
231 Main valve 235 Back pressure introduction passage 511, 511A, 511B Holding seat part (seat part)
512,512A, 512B Holding sheet surface 513,513A, 513B Outer peripheral edge

Claims (4)

A cylinder in which the working fluid is sealed, and
A piston that is slidably fitted in the cylinder and divides the cylinder into two chambers.
A piston rod whose one end side is connected to the piston and whose other end side extends to the outside of the cylinder.
The first passage through which the working fluid flows out from one chamber in the cylinder due to the movement of the piston, and
A damping force generation mechanism provided in the first passage to generate a damping force,
Equipped with
The damping force generation mechanism is
A main valve that provides resistance to the flow of working fluid from the chamber on the upstream side to the chamber on the downstream side of the first passage,
The main valve is composed of an outer cylinder portion having an opening at one end, an inner cylinder portion through which the piston rod is inserted and protrudes toward the opening side from the outer cylinder portion, and a bottom portion, and is arranged on the opening side. Is supported by a seat portion provided on the opening side end surface of the inner cylinder portion, and a bottomed tubular case member forming a back pressure chamber inside which an internal pressure is applied in the valve closing direction of the main valve.
A back pressure introduction passage for introducing a working fluid into the back pressure chamber from the chamber on the upstream side, and a back pressure introduction passage.
Have,
The sheet portion is formed so that the radial width becomes non-uniform in the circumferential direction .
The main valve is a shock absorber characterized in that the radial outer end portion is formed to have a larger diameter than the radial inner peripheral end portion of the outer cylinder portion . The shock absorber according to claim 1, wherein the outer shape of the seat portion is eccentric with respect to the central axis of the case member. The shock absorber according to claim 1, wherein the outer shape of the sheet portion has an elliptical shape. A second passage provided in parallel with the first passage is provided, and the passage is provided.
A cylindrical housing member in which at least a part of the second passage is formed, and
A drawing member that defines two variable chambers in the housing member,
The shock absorber according to any one of claims 1 to 3, further comprising a frequency sensitive portion having the above.

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