JP7206174B2 - buffer - Google Patents

Description

The present invention relates to shock absorbers.

Some shock absorbers have two valves that open in the same stroke (see Patent Document 1, for example).

Japanese Patent Publication No. 2-41666

By having two valves that open in the same stroke, one valve can be opened in a region where the piston speed is lower than the other valve, and both valves can be opened in a region where the piston speed is higher than this. It becomes possible. With such a shock absorber, a damping force of a valve characteristic (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained from a region where the piston speed is low. In such shock absorbers, there is a demand to make the damping force variable depending on the frequency.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a shock absorber capable of obtaining a damping force of valve characteristics from a region where the piston speed is low, and making it possible to vary the damping force depending on the frequency.

In order to achieve the above object, an aspect of the present invention provides a cylinder in which a working fluid is sealed, a piston movably provided in the cylinder and partitioning the inside of the cylinder into one side chamber and the other side chamber, and a piston rod connected to the piston and extending outside the cylinder; a first damping force generating mechanism provided in the first passage provided in the piston to generate a damping force; and a second passage provided in parallel with the first passage to generate a damping force. a second damping force generating mechanism, a housing provided in the second passage, the second passage provided in the housing defining the first side chamber side and the other side chamber side, and a pressure chamber in the housing. and a frequency sensitive mechanism comprising a partitioning member forming, in a region where the piston speed is low, the first damping force generating mechanism is closed and the second damping force generating mechanism is opened, and the piston In a speed range higher than a low speed, both the first damping force generating mechanism and the second damping force generating mechanism are configured to open, the second damping force generating mechanism is arranged in the one side chamber, and the The frequency sensitive mechanism is arranged in the other side chamber.

According to the present invention, it is possible to obtain a damping force of valve characteristics from a region where the piston speed is low, and to make the damping force variable depending on the frequency.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the shock absorber of 1st Embodiment which concerns on this invention. It is a partial cross-sectional view showing the vicinity of a piston of the shock absorber of the first embodiment according to the present invention. FIG. 2 is a half sectional view showing the vicinity of the frequency sensitive mechanism of the shock absorber of the first embodiment according to the present invention; FIG. 3 is a half sectional view showing the vicinity of the extremely low-speed valve mechanism of the shock absorber according to the first embodiment of the present invention; 1 is a plan view showing a disk valve of a shock absorber according to a first embodiment of the invention; FIG. 1 is a hydraulic circuit diagram of a shock absorber of a first embodiment according to the present invention; FIG. It is a Lissajous waveform of the damping force with respect to the stroke of the shock absorber of 1st Embodiment which concerns on this invention. FIG. 4 is a characteristic diagram showing damping force with respect to frequency of the shock absorber of the first embodiment according to the present invention; FIG. 4 is a characteristic diagram showing the damping force with respect to the stroke of the shock absorber of the first embodiment according to the present invention; FIG. 4 is a characteristic diagram showing damping force with respect to piston speed of the shock absorber of the first embodiment according to the present invention; It is a partial cross-sectional view showing the vicinity of the piston of the shock absorber of the second embodiment according to the present invention. FIG. 7 is a partial cross-sectional view showing the vicinity of the frequency sensitive mechanism of the shock absorber of the second embodiment according to the present invention;

[First embodiment]
A first embodiment according to the present invention will be described with reference to FIGS. 1 to 10. FIG. In the following description, for convenience of explanation, the upper side in the drawings will be referred to as "upper" and the lower side in the drawings will be referred to as "lower".

The shock absorber 1 of the first embodiment, as shown in FIG. 1, is a so-called double-cylinder hydraulic shock absorber, and includes a cylinder 2 in which hydraulic fluid (not shown) as working fluid is sealed. The cylinder 2 has a cylindrical inner cylinder 3 and a bottomed cylindrical outer cylinder 4 which has a larger diameter than the inner cylinder 3 and is concentrically provided so as to cover the inner cylinder 3. A reservoir chamber 6 is formed between the cylinder 3 and the outer cylinder 4 . The outer cylinder 4 is composed of a cylindrical body member 11 and a bottom member 12 that is fitted and fixed to the lower side of the body member 11 to close the lower portion of the body member 11 . A mounting eye 13 is fixed to the bottom member 12 on the outside opposite to the body member 11 .

The shock absorber 1 includes a piston 18 movably provided inside the inner cylinder 3 of the cylinder 2 . The piston 18 divides the interior of the inner cylinder 3 into two chambers, an upper chamber 19 (one side chamber) as one cylinder inner chamber and a lower chamber 20 (other side chamber) as the other cylinder inner chamber. there is An upper chamber 19 and a lower chamber 20 in the inner cylinder 3 are filled with oil as a working fluid, and a reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4 is filled with oil and gas as working fluids. is enclosed.

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

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

A rod guide 22 is fitted to the upper opening sides of the inner cylinder 3 and the outer cylinder 4 , and a seal member 23 is attached to the outer cylinder 4 above the rod guide 22 , which is the outer side of the cylinder 2 . there is Both the rod guide 22 and the sealing member 23 are annular, and the piston rod 21 is slidably inserted through the rod guide 22 and the sealing member 23 to extend from the inside of the cylinder 2 to the outside. is served. The piston rod 21 has one end portion fixed to the piston 18 inside the cylinder 2 and the other end portion protruding outside the cylinder 2 via a rod guide 22 and a seal member 23 .

The rod guide 22 supports the piston rod 21 axially movably while restricting its radial movement, and guides the movement of the piston rod 21 . The seal member 23 is in close contact with the outer cylinder 4 at its outer peripheral portion, and slidably contacts the outer peripheral portion of the piston rod 21 moving in the axial direction at its inner peripheral portion. It prevents the high-pressure gas and oil in the internal reservoir chamber 6 from leaking to the outside.

The outer circumference of the rod guide 22 has a stepped shape in which the diameter of the upper portion is larger than that of the lower portion. It is fitted to the inner periphery of the upper part of 4 . A base valve 25 is installed on the bottom member 12 of the outer cylinder 4 to define the lower chamber 20 and the reservoir chamber 6, and the inner peripheral portion of the lower end of the inner cylinder 3 is fitted to the base valve 25. ing. The upper end portion of the outer cylinder 4 is crimped radially inward to form a crimped portion 26 , and the crimped portion 26 and the rod guide 22 sandwich the sealing member 23 .

The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28 having a smaller diameter. A main shaft portion 27 of the piston rod 21 is slidably fitted to the rod guide 22 and the seal member 23, and a mounting shaft portion 28 is arranged in the cylinder 2 and connected to the piston 18 and the like. An end portion of the main shaft portion 27 on the mounting shaft portion 28 side forms a shaft stepped portion 29 extending in the direction perpendicular to the axis.

A passage cutout portion 30 is formed in the outer peripheral portion of the mounting shaft portion 28 at an intermediate position in the axial direction, and a male thread 31 is formed at the distal end position on the side opposite to the main shaft portion 27 in the axial direction. The passage cutout portion 30 is formed, for example, by notching the outer peripheral portion of the mounting shaft portion 28 in a plane parallel to the central axis of the mounting shaft portion 28 . The passage cutouts 30 can be formed in a so-called width across flat shape at two locations that are 180 degrees apart in the circumferential direction of the mounting shaft 28 .

The shock absorber 1 is supported by the vehicle body with, for example, the portion of the piston rod 21 protruding from the cylinder 2 arranged at the upper part, and the mounting eye 13 fixed to the cylinder 2 is arranged at the lower part and connected to the wheel side. Conversely, the cylinder 2 may be supported by the vehicle body and the piston rod 21 may be connected to the wheel side. When the wheels vibrate during running, the relative positions of the cylinder 2 and the piston rod 21 change with the vibration. is suppressed by the fluid resistance of As will be described in detail below, the fluid resistance of the flow path formed in at least one of the piston 18 and the piston rod 21 is made different depending on the speed and amplitude of vibration, and suppressing the vibration improves ride comfort. is improved. Between the cylinder 2 and the piston rod 21, not only the vibration generated by the wheels, but also the inertial force and centrifugal force generated in the vehicle body as the vehicle runs. For example, when the running direction is changed by operating the steering wheel, a centrifugal force is generated in the vehicle body, and a force based on this centrifugal force acts between the cylinder 2 and the piston rod 21 . As will be described below, the shock absorber 1 has good characteristics against vibrations caused by forces generated in the vehicle body as the vehicle travels, and high stability can be obtained while the vehicle travels.

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

The piston body 35 has a plurality of passage holes 37 (only one portion is shown in FIG. 2 because it is a cross section), and the passage holes 37 are formed at one axial end of the piston 18 (lower side in FIG. 2). A connecting annular groove 38, a plurality of passage holes 39 (only one location is shown in FIG. 2 because of the cross section), and these passage holes at the end on the other side in the axial direction of the piston 18 (upper side in FIG. 2). and an annular groove 40 connecting the grooves 39 . A plurality of passage holes 37 and an annular groove 38 can communicate the upper chamber 19 and the lower chamber 20 , and a plurality of passage holes 39 and an annular groove 40 can also communicate the upper chamber 19 and the lower chamber 20 .

A plurality of passage holes 37 are formed at an equal pitch in the circumferential direction of the piston body 35 with one passage hole 39 sandwiched therebetween, and constitute half of the passage holes 37 and 39 . In the plurality of passage holes 37, one axial side (upper side in FIG. 2) of the piston body 35 is arranged radially outward, and the other axial side (lower side in FIG. 2) is arranged radially inward. It opens into an annular groove 38 . Contrary to the passage holes 37, the plurality of passage holes 39 are arranged so that the other axial side (lower side in FIG. 2) of the piston body 35 is radially outward, and the one axial side (upper side in FIG. 2) is arranged. are arranged radially inwardly and open into the annular groove 40 .

A first damping force generating mechanism 41 that opens and closes the passages in the plurality of passage holes 37 and the annular groove 38 to generate a damping force is provided in the passages in the plurality of passage holes 37 and the annular groove 38 . The first damping force generating mechanism 41 is arranged on the lower chamber 20 side, which is one end side of the piston 18 in the axial direction, and attached to the piston rod 21 . By arranging the first damping force generating mechanism 41 on the side of the lower chamber 20 , the passages in the plurality of passage holes 37 and the annular groove 38 always communicate with the upper chamber 19 , leading to the upper chamber 19 side of the piston 18 . , that is, in the elongation stroke, the hydraulic fluid serving as the working fluid flows from the upper chamber 19 on the upstream side toward the lower chamber 20 on the downstream side. The first damping force generating mechanism 41 provided for the passages in the passage hole 37 and the annular groove 38 is designed to allow oil to flow from the passages in the passage hole 37 and the annular groove 38 on the extension side to the lower chamber 20. It is a first damping force generating mechanism on the elongation side that suppresses the flow and generates a damping force.

A first damping force generating mechanism 42 that opens and closes the passages in the passage holes 39 and the annular groove 40 to generate a damping force is provided in the passages in the plurality of passage holes 39 and the annular groove 40 . The first damping force generating mechanism 42 is arranged on the upper chamber 19 side, which is the other end side of the piston 18 in the axial direction, and attached to the piston rod 21 . By arranging the first damping force generating mechanism 42 on the upper chamber 19 side, the passages in the plurality of passage holes 39 and the annular groove 40 always communicate with the lower chamber 20, leading to the lower chamber 20 side of the piston 18. movement, that is, in the contraction stroke, oil flows from the lower chamber 20 on the upstream side to the upper chamber 19 on the downstream side. A first damping force generating mechanism 42 provided for the passages in the passage hole 39 and the annular groove 40 serves to transfer oil from the passages in the passage hole 39 and the annular groove 40 to the upper chamber 19 on the contraction side. It is a compression-side first damping force generating mechanism that suppresses flow and generates a damping force.

As described above, the passages in the plurality of passage holes 37 and the annular groove 38 and the passages in the plurality of passage holes 39 and the annular groove 40 are moved between the upper chamber 19 and the lower chamber 20 by the movement of the piston 18. It communicates so that the oil liquid which is a fluid flows. Further, when the piston rod 21 and the piston 18 move to the extension side (upper side in FIG. 2), the oil passes through the plurality of passage holes 37 and the annular groove 38, and the plurality of passage holes 39 and 38 pass through. Hydraulic fluid passes through the passage in the annular groove 40 when the piston rod 21 and the piston 18 move toward the compression side (lower side in FIG. 2).

The piston body 35 has a substantially disk shape, and an insertion hole 43 is formed in the center in the radial direction so as to pass through in the axial direction and through which the mounting shaft portion 28 of the piston rod 21 is inserted. . The insertion hole 43 has a small-diameter hole portion 44 on one axial side into which the mounting shaft portion 28 of the piston rod 21 is fitted, and a large-diameter hole portion 45 on the other axial side having a larger diameter than the small-diameter hole portion 44 . are doing. In the piston rod 21 , the inside of the passage cutout portion 30 constitutes a piston rod passage portion 46 formed by notching the piston rod 21 . The passage in the large-diameter hole portion 45 of the piston body 35 and the piston rod passage portion 46 of the mounting shaft portion 28 are always in communication.

An annular valve forming a part of the first damping force generating mechanism 41 is provided radially outward of the opening of the annular groove 38 on the lower chamber 20 side at the end of the piston body 35 on the lower chamber 20 side in the axial direction. A sheet 47 is formed. At the end of the piston body 35 on the side of the upper chamber 19 in the axial direction, an annular groove forming part of the first damping force generating mechanism 42 is provided radially outward of the opening of the annular groove 40 on the side of the upper chamber 19 . valve seat 48 is formed. Here, in the insertion hole 43 , the small-diameter hole portion 44 is provided closer to the valve seat 47 in the axial direction than the large-diameter hole portion 45 .

In the piston body 35, the radially outer side of the valve seat 47 has a stepped shape whose axial height is lower than that of the valve seat 47, and the stepped portion defines the passages in the plurality of passage holes 39 on the contraction side. An opening on the side of the lower chamber 20 is arranged. Similarly, in the piston body 35, the radially outer side of the valve seat 48 has a stepped shape whose axial height is lower than the valve seat 48, and a plurality of passage holes on the extension side are formed in this stepped portion. An opening on the upper chamber 19 side of the passage in 37 is arranged.

As shown in FIG. 3, the extension-side first damping force generating mechanism 41 is provided on the valve seat 47 side of the piston 18, and a plurality of (specifically, two) damping force generating mechanisms 41 are provided in order from the piston 18 side in the axial direction. ), a plurality of (specifically three) disks 51, one pilot disk 52, a plurality of (specifically two) disks 53, and one case member 55. , a single disc 56, a plurality of (specifically 5) discs 57, a plurality of (specifically 2) discs 58, and a plurality of (specifically 2) discs 59 , a plurality of (specifically two) discs 60 , one disc 61 and one disc 62 . These discs 50, 51, 53, 56-62, pilot disc 52, and case member 55 are provided by fitting the mounting shaft portion 28 of the piston rod 21 to the inside thereof. Disks 50, 51, 53, 56-62 and case member 55 are all made of metal. Each of the discs 50, 51, 53, 56 to 62 has a perforated circular flat plate shape with a constant thickness into which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The disc 50 has an outer diameter smaller than the inner diameter of the valve seat 47 of the piston 18 . The disk 51 has an outer diameter slightly larger than the outer diameter of the tip surface of the valve seat 47 of the piston 18 . The disk 51 can abut on the entire circumference of the valve seat 47 , and by separating and abutting against the valve seat 47 , the disk 51 can be displaced within the plurality of passage holes 37 and the annular groove 38 formed in the piston 18 shown in FIG. 2 . opens and closes the opening of the passage on the lower chamber 20 side.

As shown in FIG. 3, the pilot disk 52 is composed of a metal disk 71 and a rubber sealing member 72 fixed to the outer peripheral side of the disk 71 on one side in the axial direction (thickness direction). The disc 71 has a perforated circular flat plate shape with a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted, and has an outer diameter larger than the outer diameter of the disc 51 . The seal member 72 is fixed to the outer peripheral side of the disk 71 in the axial direction opposite to the piston 18 and has an annular shape. A plurality of discs 51 and a pilot disc 52 constitute an extension-side main valve 65 that is separated from and abuts against the valve seat 47 shown in FIG. are doing.

The passage formed between the main valve 65 and the valve seat 47 when the valve seat 47 is opened and the passages in the passage hole 37 and the annular groove 38 are stretched so that the upper chamber 19 and the lower chamber 20 communicate with each other when the main valve 65 is opened. It constitutes a first passage 75 on the side. The first passage 75 is provided in the piston 18 , and the oil moves from the upper chamber 19 on the upstream side in the cylinder 2 to the lower chamber 20 on the downstream side as the piston 18 moves. The first damping force generating mechanism 41 is provided in the first passage 75 and opens and closes the first passage 75 to generate damping force.

The first damping force generating mechanism 41 on the extension side has a fixed orifice that allows communication between the upper chamber 19 and the lower chamber 20 even when the valve seat 47 and the main valve 65 abutting thereon are in contact with each other. is not formed. That is, the extension-side first damping force generating mechanism 41 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other if the valve seat 47 and the main valve 65 are in contact over the entire circumference. In other words, the first passage 75 does not have a fixed orifice that always communicates the upper chamber 19 and the lower chamber 20, and thus the first passage 75 always communicates the upper chamber 19 and the lower chamber 20. not an aisle.

As shown in FIG. 3 , the disc 53 has an outer diameter smaller than the minimum inner diameter of the seal member 72 of the pilot disc 52 . The disc 53 has an outer diameter smaller than that of the disc 50 .

The case member 55 has a bottomed tubular shape and an annular shape. The case member 55 is formed with a through hole 80 penetrating in the thickness direction at the center in the radial direction. a cylindrical inner cylindrical portion 82 protruding to both sides of the bottom portion 81; a cylindrical outer cylindrical portion 83 protruding from the outer peripheral edge portion of the bottom portion 81 to one side along the axial direction of the bottom portion 81; and an annular valve seat 84 projecting axially from the bottom portion 81 toward the opposite side of the outer cylindrical portion 83 from an intermediate position in the direction of the bottom portion 81 . The mounting shaft portion 28 of the piston rod 21 passes through the through hole 80 of the case member 55 . The bottom portion 81, the inner cylindrical portion 82, the outer cylindrical portion 83 and the valve seat 84 are arranged coaxially.

A through hole 91 is formed through the bottom portion 81 along the axial direction between the outer cylindrical portion 83 and the valve seat 84 and the inner cylindrical portion 82 in the radial direction of the bottom portion 81 . A plurality of through holes 91 are formed in the bottom portion 81 at intervals in the circumferential direction of the bottom portion 81 (only one portion is shown in FIG. 3 because of the partial cross section). At least one through hole 91 may be provided in the bottom portion 81 .

The through hole 80 on the inner peripheral side of the inner cylindrical portion 82 has a small-diameter hole portion 92 on the opposite side of the valve seat 84 in the axial direction, into which the mounting shaft portion 28 of the piston rod 21 is fitted. A large-diameter hole portion 93 having a diameter larger than that of the small-diameter hole portion 92 is provided on the valve seat 84 side in the direction. A part of the mounting shaft portion 28 of the piston rod 21 inserted through the through hole 80 is arranged in the case member 55 in the axial direction. The passage in the large-diameter hole portion 93 of the case member 55 and the piston rod passage portion 46 of the mounting shaft portion 28 are always in communication.

The seal member 72 is slidably and liquid-tightly fitted over the entire circumference of the inner peripheral surface of the outer cylindrical portion 83 of the case member 55 , so that the gap between the pilot disk 52 and the outer cylindrical portion 83 is always maintained. to seal. In other words, the pilot disk 52 slidably and liquid-tightly engages the seal member 72 with the outer cylindrical portion 83 of the case member 55 .

The disk 56 has an outer diameter smaller than the inner diameter of the tip surface of the valve seat 84 of the case member 55 . The disc 56 is formed with a notch portion 101 extending radially outward from an inner peripheral edge portion that fits onto the mounting shaft portion 28 of the piston rod 21 . The disk 56 comes into contact with the inner cylindrical portion 82 of the case member 55, and the notch 101 traverses the inner cylindrical portion 82 in the radial direction.

The plurality of discs 57 have the same outer diameter, which is slightly larger than the outer diameter of the tip surface of the valve seat 84 of the case member 55 . The plurality of discs 58 have the same outer diameter and are smaller than the outer diameter of the disc 57 . The plurality of discs 59 have the same outer diameter and are smaller than the outer diameter of the disc 58 . The plurality of discs 60 have the same outer diameter and are smaller than the outer diameter of the disc 59 .

Disks 57 - 60 constitute hard valve 110 . A pilot chamber 111 that applies back pressure to the pilot disk 52 is formed between the pilot disk 52 , the case member 55 and the hard valve 110 . A valve seat 84 surrounds the opening of the pilot chamber 111 on the side opposite to the piston 18 .

The hard valve 110 can contact the valve seat 84 at the disk 57 , and opens and closes the pilot chamber 111 by separating from and contacting the valve seat 84 . When the hard valve 110 leaves the valve seat 84 , the pilot chamber 111 communicates with the lower chamber 20 . The passage in the notch portion 101 of the disc 56 is always communicated with the pilot chamber 111 on the one hand and with the piston rod passage portion 46 on the other hand. The passage in the notch portion 101 is provided between the pilot chamber 111 and the piston rod passage portion 46 and serves as a restriction, that is, an orifice 112 that narrows the flow passage cross-sectional area.

The disk 61 has an outer diameter smaller than the outer diameter of the disk 60 having the smallest diameter among the hard valves 110 . The disk 62 has an outer diameter equivalent to the outer diameter of the intermediate disk 59 of the hard valve 110 .

As shown in FIG. 2, on the mounting shaft portion 28 of the piston rod 21, on the side opposite to the first damping force generating mechanism 42 of the first damping force generating mechanism 41, there is provided a damping force variable in response to the piston frequency. A frequency-sensitive mechanism 121 is provided for.

As shown in FIG. 3, the frequency sensitive mechanism 121 includes, in order from the disk 62 side in the axial direction, one housing 122 that contacts the disk 62, a plurality of (specifically two) disks 123, and one housing. It has a partition disk 124 (partition member, disk), one disk 125 , one disk 126 and one stopper member 127 . Housing 122, discs 123, 125, 126 and stopper member 127 are made of metal. Each of the discs 123, 125 and 126 has a perforated circular flat plate shape with a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted. The housing 122 and the stopper member 127 have an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted. A part of the mounting shaft portion 28 of the piston rod 21 is arranged inside the housing 122 .

The housing 122 includes a perforated disc-shaped bottom portion 141 (first bottom portion) and a cylindrical tubular portion 142 (first tubular portion) that protrudes from the outer peripheral side of the bottom portion 141 to one side along the axial direction of the bottom portion 141 . It is a cylindrical shape with a bottom. A through hole 144 is formed in the center in the radial direction of the bottom portion 141 . The bottom portion 141 includes a perforated disc-shaped bottom portion body portion 145, an annular projecting portion 146 projecting from the inner peripheral side of the bottom portion body portion 145 toward the cylinder portion 142 side in the axial direction from the bottom portion body portion 145, and a bottom portion. An annular support portion 147 protrudes from between the projecting portion 146 and the cylindrical portion 142 of the main body portion 145 toward the cylindrical portion 142 in the axial direction from the bottom main body portion 145 . In other words, the bottom portion 141 has a protruding portion 146 protruding on the inner peripheral side of the bottom main body portion 145 on the same side as the cylindrical portion 142 than the bottom main body portion 145 at a radially intermediate position on the same side as the cylindrical portion 142 rather than the bottom main body portion 145 . A protruding support portion 147 is formed respectively.

A channel groove 151 is partially formed in the circumferential direction of the projecting portion 146 so as to traverse the projecting portion 146 in the radial direction. A channel groove 152 is partially formed in the support portion 147 in the circumferential direction so as to traverse the support portion 147 in the radial direction. The through-hole 144 has a small-diameter hole portion 155 on the side opposite to the axial protrusion 146, into which the mounting shaft portion 28 of the piston rod 21 is fitted, and a small-diameter hole portion on the axial protrusion 146 side. It has a large diameter hole portion 156 having a larger diameter than 155 . The channel groove 151 opens into the large-diameter hole portion 156 . The passage in the large diameter hole portion 156 of the housing 122 and the piston rod passage portion 46 of the mounting shaft portion 28 are always in communication. The side of the cylindrical portion 142 opposite to the bottom portion 141 is an opening. The cylindrical portion 142 has a tapered inner peripheral surface in which the inner diameter increases from the bottom portion 141 toward the opening. The stopper member 127 is provided on the opening side of the cylindrical portion 142 of the bottomed cylindrical housing 122 .

A mounting shaft portion 28 extends axially through the radial center of the housing 122 , and a plurality of discs 123 , partition discs 124 , discs 125 and discs 126 are arranged in the housing 122 with the mounting shaft portions 28 inside each of them. It is arranged so that it penetrates the

The bottom 141 of the housing 122 supports the inner peripheral side of the disc 62 at its outer end on the side of the small-diameter hole 155 in the axial direction, and the inner end on the side of the large-diameter hole 156 in the axial direction. The portion 146 supports the outer peripheral side of the disk 123 . The support portion 147 of the housing 122 supports the intermediate position in the radial direction of the annular partition disk 124 at the end on the projecting tip side. By forming the channel groove 152 in the support portion 147 , the radially inner side and the radially outer side of the support portion 147 in the housing 122 always communicate with each other.

The plurality of discs 123 have an outer diameter smaller than the outer diameter of the tip surface of the protrusion 146 of the housing 122 and larger than the inner diameter of the tip surface of the protrusion 146 .

The partition disk 124 is composed of a perforated circular plate-shaped flexible disk 161 made of a metal material and having a fixed thickness, and an elastic sealing member 162 made of a rubber material and fixed to the outer peripheral side of the disk 161 . Compartment disk 124 is generally circular and elastically deformable or bendable.

The annular disk 161 has an inner diameter larger than the outer diameter of the disk 123, and has an inner diameter that allows the disk 123 to be arranged inside with a gap in the radial direction. The disc 161 is thinner than the thickness of the discs 123 (two discs). The disk 161 has an inner diameter smaller than the outer diameter of the disk 125 and can abut on the disk 125 . The disk 161 has an outer diameter larger than the outer diameter of the tip surface of the support portion 147 of the housing 122 and smaller than the inner diameter of the cylindrical portion 142 . The disk 161 is arranged in the housing 122 with the mounting shaft portion 28 penetrating inside. The disc 161 is provided within the housing 122 in contact with the support portion 147 of the bottom portion 141 . The inner peripheral surface of the tubular portion 142 of the housing 122 has a tapered shape in which the inner diameter increases with increasing distance from the bottom portion 141 toward the partition disk 124 side.

The seal member 162 is fixed to the outer peripheral side of the disk 161 in an annular shape. The sealing member 162 has the entire surface facing the disk 161 fixed to the disk 161 . The seal member 162 has a seal portion 171 protruding from the disc 161 in the axial direction opposite to the stopper member 127 and a contact portion 172 protruding from the disc 161 in the axial direction toward the stopper member 127 . The seal portion 171 has a cylindrical shape and is fixed to the disk 161 over the entire circumference. The seal portion 171 is slidably and liquid-tightly fitted over the entire circumference of the inner peripheral surface of the tubular portion 142 of the housing 122 to always seal between the tubular portion 142 and the partition disk 124 .

The contact portions 172 are intermittently formed in the circumferential direction of the disc 161 . When the partition disk 124 deforms toward the stopper member 127, the contact portion 172 contacts the stopper member 127 and is elastically deformed. The seal portion 171 covers the outer peripheral surface of the disk 161 and is connected to the contact portion 172 .

The partition disk 124 is centered with respect to the housing 122 by contacting the cylindrical portion 142 of the housing 122 with the sealing portion 171 over the entire circumference, and as a result, is also centered with respect to the mounting shaft portion 28 . The partition disk 124 is supported with its disk 161 in contact with the support portion 147 of the housing 122 .

The protrusion 146 of the housing 122 and the disc 125 have an outer diameter larger than the inner diameter of the disc 161 of the partition disc 124 . Therefore, the inner peripheral side of the disc 161 is arranged between the protrusion 146 of the housing 122 and the disc 125, and the partition disc 124 is axially movable within the range between them. When there is no pressure difference between the front side and the back side of the partitioning disc 124, the disc 161 abuts on the supporting portion 147 on one side in the thickness direction and the disc 125 on the other side in the thickness direction. supported by The disk 125 is a seat portion on which the partition disk 124 is seated.

Compartment disc 124 is disposed within housing 122 in a deflectable manner. The inner peripheral side of the disc 161 of the partition disc 124 is movable between the projecting portion 146 of the housing 122 and the disc 125 within the axial length range of the plurality of discs 123 . Also, the partition disk 124 is provided with an annular seal portion 171 for sealing between the disk 161 and the housing 122 on the outer peripheral side, which is the non-supported side opposite to the support by the disk 125 of the disk 161 . The partition disk 124 has a simple support structure in which the inner peripheral side thereof is supported by the disk 125 only on one side without being clamped from both sides. The disk 126 has an outer diameter larger than that of the disk 125 .

The stopper member 127 has a cylindrical tubular portion 181 and a disk-shaped flange portion 182 extending radially outward from the axial center position of the outer peripheral portion of the tubular portion 181 . The cylindrical portion 181 is thicker than the flange portion 182 on both sides in the axial direction. The mounting shaft portion 28 of the piston rod 21 is fitted inside the cylindrical portion 181 of the stopper member 127 .

The flange portion 182 of the stopper member 127 is arranged axially outside the cylindrical portion 142 of the housing 122 , and a communicating passage 185 is formed between the stopper member 127 and the cylindrical portion 142 to constantly communicate the inside of the housing 122 with the lower chamber 20 . forming.

Here, the stopper member 127 has a mirror-symmetrical shape with reference to a plane that passes through the center position in the axial direction and is perpendicular to the axial direction. In other words, the stopper member 127 has a shape that does not discriminate between the front and back and does not cause erroneous assembly due to a mistake in the front and back. The stopper member 127 can be formed by sintering.

The seal portion 171 of the partition disk 124 is in contact with the inner peripheral surface of the tubular portion 142 of the housing 122 over the entire circumference to seal the gap between the partition disk 124 and the tubular portion 142 . Thus, the compartment disc 124 is a packing valve. The seal portion 171 always seals the gap between the partition disk 124 and the cylindrical portion 142 even if the partition disk 124 is displaced and deformed within the allowable range between the housing 122 and the stopper member 127 . The partition disk 124 is centered by being fitted into the housing 122, and in this state, the inner peripheral portion of the disk 161 is brought into contact with the disk 125 over the entire circumference, thereby sealing the gap with the disk 125. .

The partition disk 124 forms a variable volume pressure chamber 191 on the bottom 141 side in the housing 122 . The partition disk 124 forms a communication chamber 192 with the stopper member 127 . The communication chamber 192 always communicates with the lower chamber 20 via the communication passage 185 . A pressure chamber 191 is formed between the partition disk 124 and the bottom 141 of the housing 122 . A passage in the flow channel groove 151 of the protruding portion 146 is provided between the pressure chamber 191 and the piston rod passage portion 46 to reduce the cross-sectional area of the flow passage, that is, an orifice 193 . The partition disc 124 and the disc 125 as its seat portion restrict the flow of oil from the pressure chamber 191 to the communication chamber 192, while allowing the flow of oil from the communication chamber 192 to the pressure chamber 191. It constitutes a valve 195 .

As shown in FIG. 4, the compression-side first damping force generating mechanism 42 is provided on the valve seat 48 side of the piston 18, and includes one disc 201 and a plurality of discs 201 in order from the piston 18 side in the axial direction. It has (specifically, four) disks 202 , a plurality of (specifically, two) disks 203 , and one disk 204 . These discs 201 to 204 are provided by fitting the mounting shaft portion 28 of the piston rod 21 to the inside thereof. All of the disks 201-204 are made of metal. Each of the discs 201 to 204 is in the form of a perforated circular flat plate having a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The disc 201 has an outer diameter smaller than the inner diameter of the tip surface of the valve seat 48 of the piston 18 . The disk 201 is formed with a cutout portion 211 extending radially outward from an inner peripheral edge portion that fits onto the mounting shaft portion 28 of the piston rod 21 . The passage in the notch 211 of the disk 201 always communicates with passages in the compression-side passage hole 39 and the annular groove 40 on the one hand, and always communicates with the piston rod passage portion 46 on the other. The passage in the notch portion 211 is a restriction that is provided between the passages in the compression-side passage hole 39 and the annular groove 40 and the piston rod passage portion 46 to reduce the cross-sectional area of the passage. It's becoming As shown in FIG. 2, the passages in the compression side passage hole 39 and the annular groove 40 are in constant communication with the lower chamber 20, so that between the lower chamber 20 and the piston rod passage portion 46, as shown in FIG. 4 is provided with an introduction orifice 212 .

The plurality of discs 202 have the same outer diameter, which is slightly larger than the outer diameter of the tip surface of the valve seat 48 . The disk 202 can abut on the valve seat 48 over its entire circumference, and by separating and abutting against the valve seat 48, opens and closes the openings of the passages in the passage hole 39 and the annular groove 40 formed in the piston 18. .

The plurality of discs 203 have the same outer diameter, which is smaller than the outer diameter of the disc 202 . The disk 204 has an outer diameter smaller than that of the disk 203 . A plurality of discs 202 and a plurality of discs 203 form a main valve 221 that is spaced apart from and abuts against the valve seat 48 to open and close passages in the contraction-side passage hole 39 and the annular groove 40 .

When the main valve 221 is open, the passage between the main valve 221 and the valve seat 48 and the passages in the passage hole 39 and the annular groove 40 contract to communicate the lower chamber 20 and the upper chamber 19 when the main valve 221 is open. It constitutes a first passage 222 on the side. The first passage 222 is provided in the piston 18 , and movement of the piston 18 moves the oil from the lower chamber 20 on the upstream side in the cylinder 2 to the upper chamber 19 on the downstream side. The first damping force generating mechanism 42 is provided in the first passage 222 and opens and closes the first passage 222 to generate damping force.

The first damping force generating mechanism 42 on the compression side has a fixed orifice that allows communication between the upper chamber 19 and the lower chamber 20 even when the valve seat 48 and the main valve 221 contacting the valve seat 48 are in contact with each other. is not formed. That is, the compression side first damping force generating mechanism 42 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other if the valve seat 48 and the main valve 221 are in contact with each other over the entire circumference. In other words, the first passage 222 does not have a fixed orifice that constantly communicates the upper chamber 19 and the lower chamber 20, and thus the first passage 222 always communicates the upper chamber 19 and the lower chamber 20. is not.

As shown in FIG. 2, on the mounting shaft portion 28 of the piston rod 21, a very low speed valve mechanism 231 is provided on the side opposite to the first damping force generating mechanism 42 on the contraction side and the first damping force generating mechanism 41 on the extension side. is provided. In other words, the extremely low-speed valve mechanism 231 is provided on the same side as the main valve 221 on the compression side with respect to the piston 18 , and is provided on the side opposite to the piston 18 with respect to the main valve 221 .

As shown in FIG. 4, the extremely low-speed valve mechanism 231 includes, in order from the axial step portion 29 side of the piston rod 21, an annular member 241, a disc 242, a plurality of (specifically, two) discs 243, It has one disc 244 , one disc 245 , one disc 246 , one disc valve 247 , and one case member 248 . The annular member 241, the discs 242 to 246, the disc valve 247 and the case member 248 are all made of metal, and are provided with the mounting shaft portion 28 of the piston rod 21 fitted therein.

The annular member 241, the discs 242 to 246 and the disc valve 247 are formed in the shape of a perforated circular flat plate having a constant thickness in which the mounting shaft portion 28 of the piston rod 21 can be fitted. The case member 248 has an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The case member 248 is a bottomed cylindrical integrally molded product, and includes a perforated disk-shaped bottom portion 261 (second bottom portion) and a circle projecting from the outer peripheral edge portion of the bottom portion 261 to one side in the axial direction of the bottom portion 261 . It has an annular outer tubular portion 262 (second tubular portion) and an annular inner tubular portion 263 protruding from the inner peripheral edge portion of the bottom portion 261 in the same direction as the outer tubular portion 262 . The outer tubular portion 262 and the inner tubular portion 263 are coaxially arranged, and the outer tubular portion 262 protrudes from the bottom portion 261 longer than the inner tubular portion 263 . The case member 248 is arranged in such a manner that the bottom portion 261 is located closer to the piston 18 than the outer tubular portion 262 and the inner tubular portion 263 , and the bottom portion 261 contacts the disk 204 .

The outer tubular portion 262 has an annular shape that is continuous over the entire circumference, and the inner peripheral surface is a tapered surface that increases in diameter with distance from the bottom portion 261 in the axial direction. The outer peripheral surface of the outer tubular portion 262 forms the same cylindrical surface as the outer peripheral surface of the bottom portion 261 . A tip surface of the outer cylindrical portion 262 on the side opposite to the bottom portion 261 in the axial direction is a plane perpendicular to the central axis of the case member 248 .

A corner edge on the boundary side between the tip end surface and the inner peripheral surface of the outer cylindrical portion 262 forms an annular shape, and serves as a first valve seat 271 on which the disk valve 247 is seated. Therefore, the first valve seat 271 is annularly formed on the outer cylindrical portion 262 of the case member 248 .

The inner cylindrical portion 263 has a tapered outer peripheral surface whose diameter decreases with distance from the bottom portion 261 in the axial direction. They are perpendicular planes. A plurality of passage grooves 272 are formed in the inner cylindrical portion 263 at intervals in the circumferential direction, the passage grooves 272 being open at the distal end surface and penetrating in the radial direction. Therefore, the inner cylindrical portion 263 is not continuous over the entire circumference, but intermittently formed in the circumferential direction.

The case member 248 has an insertion hole 275 formed in its radial center, which axially penetrates the bottom portion 261 and the inner cylindrical portion 263 and through which the mounting shaft portion 28 of the piston rod 21 is inserted. The insertion hole 275 has a small-diameter hole portion 276 on one axial side into which the mounting shaft portion 28 of the piston rod 21 is fitted, and a large-diameter hole portion 277 on the other axial side having a larger diameter than the small-diameter hole portion 276 . are doing. The large-diameter hole portion 277 is mainly formed in the inner cylindrical portion 263 , and the small-diameter hole portion 276 is mainly formed in the bottom portion 261 . All of the plurality of passage grooves 272 are open on the inner peripheral surface of the large-diameter hole portion 277 .

A passage in the large-diameter hole portion 277 always communicates with the piston rod passage portion 46 of the piston rod 21 . The passage in the passage groove 272 of the inner cylindrical portion 263 is also always communicated with the piston rod passage portion 46 via the passage in the large diameter hole portion 277 .

The annular member 241 has an outer diameter larger than the outer diameter of the shaft stepped portion 29, and is thicker than the discs 242 to 246 and the disc valve 247 and has high rigidity. This annular member 241 is in contact with the shaft stepped portion 29 of the piston rod 21 . The disk 242 has an outer diameter larger than that of the annular member 241 . The plurality of discs 243 have the same outer diameter, which is smaller than the outer diameter of the annular member 241 .

The disk 244 has an outer diameter larger than that of the disk 243 . The disk 245 has an outer diameter larger than that of the disk 244 . The disk 246 has an outer diameter larger than that of the disk 245 . Therefore, the outer diameters of the disks 243 to 246 increase as they are closer to the case member 248 in the axial direction.

The outer diameter of the disc 246 is smaller than the inner diameter of the tip surface of the outer cylindrical portion 262 of the case member 248 , in other words, the inner diameter of the first valve seat 271 . Further, the outer diameter of the disc 246 is larger than the outer diameter of the tip surface of the inner cylindrical portion 263 of the case member 248 . A position offset by the thickness of the disk valve 247 toward the bottom portion 261 from the end surface of the disk 246 on the bottom portion 261 side is the tip surface of the outer tubular portion 262 of the case member 248, in other words, the bottom portion 261 of the first valve seat 271. are arranged closer to the bottom portion 261 in the axial direction than the tip surface on the opposite side.

A disk valve 247 is seated and separated from the annular outer peripheral portion of the disk 246 on the bottom 261 side in the axial direction. The disc 246, together with the discs 244 and 245 laminated thereon, constitutes a second valve seat 281 on which the disc valve 247 is seated. In other words, the second valve seat 281 supports the disc valve 247 when seated. A second valve seat 281 consisting of discs 244 to 246 allows the piston rod 21 to pass therethrough in the radial direction.

The second valve seat 281 is spaced radially inward from the first valve seat 271 of the case member 248 . The position offset from the end surface of the second valve seat 281 on the bottom portion 261 side by the thickness of the disk valve 247 toward the bottom portion 261 side is axially greater than the tip surface of the first valve seat 271 opposite to the bottom portion 261 . It is located on the bottom 261 side. The outer diameters of the disks 244 to 246 become smaller the further they are from the bottom 261 in the axial direction. Since these discs 244 to 246 are made of thin metal plates, the second valve seat 281 made up of the discs 244 to 246 is configured to be flexible. On the other hand, the first valve seat 271 of the case member 248 has higher rigidity than the second valve seat 281 and basically does not bend. The second valve seat 281 can adjust the support rigidity of the disc valve 247 by changing the thickness, outer diameter, number of discs 244 to 246, and the like.

The outer diameter of the disk 243 is slightly larger than the outer diameter of the tip surface of the inner cylindrical portion 263 of the case member 248 .

The disc valve 247 is made of a single thin metal plate and is flexible. The disc valve 247 has a flat plate shape in its natural state before it is incorporated into the shock absorber 1 . As shown in FIG. 5, the disc valve 247 in its natural state has an outer annular portion 291 in the form of a perforated circular flat plate and an outer diameter smaller than the inner diameter of the outer annular portion 291. It has a perforated circular plate-shaped inner annular portion 292 arranged on the direction inner side, and a plurality of, specifically two support portions 293 connecting the outer annular portion 291 and the inner annular portion 292 . A space is formed between the outer annular portion 291 and the inner annular portion 292 except for the two support portions 293 . The disk valve 247 has a mirror-symmetrical shape with respect to a plane including the central axis.

The outer annular portion 291 has circular outer and inner peripheral surfaces that are concentrically arranged, in other words, it forms an annular shape with a constant radial width. The inner annular portion 292 also has circular outer and inner peripheral surfaces that are concentrically arranged, in other words, it forms an annular shape with a constant radial width. The two support portions 293 are arranged between the inner annular portion 292 and the outer annular portion 291 and concentrically support the outer annular portion 291 on the inner annular portion 292 .

As shown in FIG. 4, the inner annular portion 292 has the mounting shaft portion 28 of the piston rod 21 inserted therein. The inner annular portion 292 has an inner diameter capable of fitting the mounting shaft portion 28 of the piston rod 21 , and an outer diameter smaller than the outer diameter of the disc 246 , that is, the outer diameter of the second valve seat 281 . The outer diameter of the inner annular portion 292 is slightly larger than the outer diameter of the tip surface of the inner cylindrical portion 263 of the case member 248 . Thus, disc valve 247 is axially clamped between disc 243 and inner cylindrical portion 263 along with discs 244 - 246 at inner annular portion 292 . Note that the outer diameter of the inner annular portion 292 may be smaller than the outer diameter of the distal end surface of the inner cylindrical portion 263 of the case member 248 .

The outer annular portion 291 has an inner diameter smaller than the outer diameter of the disc 246, that is, the outer diameter of the second valve seat 281, and has an outer diameter that is smaller than the inner diameter of the tip surface of the outer cylindrical portion 262 of the case member 248, that is, the second valve seat 281. It has a larger diameter than the diameter of one valve seat 271 . The outer diameter of the outer annular portion 291 , that is, the outer diameter of the disc valve 247 is larger than the outer diameter of the main valve 221 .

The annular disk valve 247 has an outer annular portion 291 that can be separated from the first valve seat 271 of the case member 248 at an outer peripheral side contact portion 301 (separate contact portion). The outer annular portion 291 closes the gap with the first valve seat 271 when the outer peripheral side separation/contact portion 301 is seated on the first valve seat 271 over the entire circumference, and closes the first valve seat when it is separated from the first valve seat 271. 271 is opened.

In addition, the outer annular portion 291 is configured such that an inner peripheral side separating/contacting portion 302 on the inner peripheral side can be brought into and out of contact with the second valve seat 281 of the disk 246 . The outer annular portion 291 closes the gap with the second valve seat 281 when the inner peripheral side separation/contact portion 302 is seated on the second valve seat 281 over the entire circumference, and when the inner peripheral side separation/contact portion 302 is seated on the second valve seat 281, the second valve is closed. The gap with the sheet 281 is opened. When the outer annular portion 291 is seated on the second valve seat 281 , the disk 246 closes the gap between the outer annular portion 291 and the inner annular portion 292 of the disk valve 247 .

Therefore, the disk valve 247 is arranged so that the outer peripheral side separation/contact portion 301 on the outer peripheral side can be separated from the first valve seat 271 of the case member 248 . The second valve seat 281 is provided on the opposite side of the first valve seat 271 in the axial direction of the disc valve 247, and is located radially inward of the outer peripheral separation portion 301 of the disc valve 247. 302 is detachably supported. The disc valve 247 includes an outer annular portion 291 that is detachably arranged on the first valve seat 271 and the second valve seat 281, an inner annular portion 292 that is fitted to the piston rod 21 and fixed in the axial direction, It has a support portion 293 that connects the outer annular portion 291 and the inner annular portion 292 .

As shown in FIG. 5 , the two support portions 293 have two outer connection portions 311 , two inner connection portions 312 , and two connecting arm portions 313 .

The two outer connection portions 311 are arranged on the same side of the center in the radial direction of the disk valve 247 and are spaced apart in the circumferential direction of the disk valve 247 and connected to the outer annular portion 291 . . Both of the two outer connection portions 311 protrude radially inward of the outer annular portion 291 from the inner peripheral edge portion of the outer annular portion 291 .

The two inner connection portions 312 are spaced apart in the circumferential direction of the disc valve 247 on the same opposite side of the center of the disc valve 247 , that is, on the side opposite to the two outer connection portions 311 . and is connected to the inner annular portion 292 . The two inner connection portions 312 both protrude radially outward of the inner annular portion 292 from the outer peripheral edge portion of the inner annular portion 292 .

Here, the interval between the two inner connection portions 312 is wider than the interval between the two outer connection portions 311 . A straight line connecting the two inner connection portions 312 and a straight line connecting the two outer connection portions 311 are parallel to each other. Therefore, the straight line connecting the midpoint of the straight line connecting the two inner connecting portions 312 and the midpoint of the straight line connecting the two outer connecting portions 311 is the center of the inner annular portion 292 and the outer annular portion 291, That is, it passes through the center of the disc valve 247 . The distance between the outer connection portion 311 and the inner connection portion 312 that are closer to each other in the circumferential direction of the disk valve 247 is equal to the distance between the outer connection portion 311 and the inner connection portion 312 that are closer to each other in the circumferential direction of the disk valve 247. ing. This distance is longer than the distance connecting the two inner connection portions 312 and longer than the distance connecting the two outer connection portions 311 .

The two connecting arm portions 313 are provided so as to connect the outer connecting portion 311 and the inner connecting portion 312 which are close to each other in the circumferential direction of the disc valve 247 . That is, one connecting arm portion 313 connects one outer connecting portion 311 and one inner connecting portion 312 which are close in the circumferential direction of the disk valve 247, and the outer connecting portion 311 and the inner connecting portion 312 are connected. and constitute one support portion 293 . On the other hand, the other connecting arm portion 313 connects the other outer connection portion 311 and the other inner connection portion 312 that are close to each other in the circumferential direction of the disk valve 247 . and constitute the other support portion 293 .

Here, the two connecting arm portions 313 extend in an arc shape along the inner peripheral surface of the outer annular portion 291 and the outer peripheral surface of the inner annular portion 292 and are concentric with the outer annular portion 291 and the inner annular portion 292 . are arranged on the same circle. The two connecting arms 313 have the same radial distance from the inner peripheral surface of the outer annular portion 291 and the same radial distance from the outer peripheral surface of the inner annular portion 292 .

As shown in FIG. 4, when the outer annular portion 291 of the disc valve 247 is seated on the second valve seat 281 at the inner peripheral side contact portion 302 on the inner peripheral side, the disc 246 constituting the second valve seat 281 is It isolates between the outer annular portion 291 and the inner annular portion 292 of the disk valve 247 . In other words, the second valve seat 281 is provided so as to block the space between the outer annular portion 291 and the inner annular portion 292 of the disc valve 247 . Disk valve 247 and case member 248 form a case interior chamber 321 therein.

The case inner chamber 321 always communicates with the piston rod passage portion 46 of the piston rod 21 via passages in the passage groove 272 and the large diameter hole portion 277 of the inner cylindrical portion 263 . As shown in FIG. 3, the pilot chamber 111 also always communicates with the piston rod passage portion 46 of the piston rod 21 through the orifice 112 in the notch portion 101 of the disk 56. As shown in FIG. Furthermore, the pressure chamber 191 of the frequency sensitive mechanism 121 also always communicates with the piston rod passage portion 46 of the piston rod 21 via the orifice 193 . As shown in FIG. 4, the piston rod passage portion 46 includes a passage in the large diameter hole portion 45 of the piston 18, an introduction orifice 212 in the notch portion 211 of the disk 201, an annular groove 40 in the piston 18 and It always communicates with the lower chamber 20 via passages in the plurality of passage holes 39 . Therefore, the case inner chamber 321 , the pilot chamber 111 and the pressure chamber 191 always communicate with the lower chamber 20 .

The inner peripheral side of the outer annular portion 291 of the disc valve 247 including the inner peripheral side contact/separation portion 302 constitutes a sub-valve 331 that can be seated on and removed from the second valve seat 281 . The sub-valve 331 is provided on the upper chamber 19 side of the upper chamber 19 and the lower chamber 20 .

When the sub-valve 331 is separated from the second valve seat 281 , the upper chamber 19 moves through the gap with the second valve seat 281 and the passage between the outer annular portion 291 and the inner annular portion 292 of the disk valve 247 . and the case inner chamber 321 , thereby connecting the upper chamber 19 to the lower chamber 20 . At this time, the sub-valve 331 suppresses the flow of fluid between itself and the second valve seat 281 to generate a damping force. The sub-valve 331 is an inflow valve that opens when oil is allowed to flow from the upper chamber 19 into the case inner chamber 321 through the gap between the second valve seat 281 and the second valve from the case inner chamber 321 to the upper chamber 19. Outflow of the oil through the gap with the sheet 281 is restricted.

The passage between the sub-valve 331 and the second valve seat 281 appearing when the valve is opened, the passage between the outer annular portion 291 and the inner annular portion 292 of the disk valve 247, the case inner chamber 321, and the passage groove of the case member 248. 272 and the large diameter hole 277, the piston rod passage 46 of the piston rod 21, the passage in the large diameter hole 45 of the piston 18, the introduction orifice 212 in the notch 211 of the disc 201, As the piston 18 moves toward the upper chamber 19 side, oil flows from the upper chamber 19 on the upstream side in the cylinder 2 to the lower chamber 20 on the downstream side. It constitutes a second passage 332 from which it flows.

As shown in FIG. 3 , the second passage 332 includes a passage in the large-diameter hole portion 93 of the case member 55 communicating with the piston rod passage portion 46 , an orifice 112 in the notch portion 101 of the disk 56 , and the pilot chamber 111 . , a passage in the large diameter hole portion 156 of the housing 122 communicating with the piston rod passage portion 46, an orifice 193 in the passage groove 151, and a pressure chamber 191 separated from the communication chamber 192 by the check valve 195. contains.

The second passage 332 serves as an elongation-side passage through which oil flows from the upper chamber 19 on the upstream side toward the lower chamber 20 on the downstream side during the movement of the piston 18 toward the upper chamber 19 side, that is, the extension stroke. When the hard valve 110 opens and leaves the valve seat 84 , the pilot chamber 111 of the second passage 332 communicates with the lower chamber 20 .

The second passage 332 includes the piston rod passage portion 46 in the passage cutout portion 30 formed by notching the piston rod 21, in other words, a part thereof is formed by notching the piston rod 21. . In addition to forming the piston rod 21 by notching, the passage in the large diameter hole portion 277 of the case member 248 shown in FIG. 4, the passage in the large diameter hole portion 45 of the piston 18, and the case member shown in FIG. A piston rod passage portion 46 is formed by passing through the inside of the piston rod 21 in a hole shape so as to open to the passage of the large diameter hole portion 93 of 55 and the passage in the large diameter hole portion 156 of the housing 122 . Also good. In other words, the second passage 332 may include the piston rod passage portion 46 formed by notching or penetrating the piston rod 21 .

A sub-valve 331 and a second valve seat 281, shown in FIG. It constitutes a second damping force generating mechanism 333 on the extension side that suppresses the flow and generates a damping force. The sub-valve 331 that constitutes the extension-side second damping force generating mechanism 333 is an extension-side sub-valve. As shown in FIG. 2, a second damping force generating mechanism 333 comprising a sub-valve 331 and a second valve seat 281 has the piston rod 21 inserted radially inward. 19 and one of the lower chambers 20 on the upper chamber 19 side.

In the second passage 332, when the second damping force generating mechanism 333 is in the open state, the introduction orifice 212 in the notch 211 of the disc 201 shown in FIG. It becomes a throttle in the second passage 332 . The introduction orifice 212 is arranged downstream of the sub-valve 331 when the sub-valve 331 is open and the oil flows through the second passage 332 . In other words, the introduction orifice 212 is arranged closer to the lower chamber 20 than the sub-valve 331 in the second passage 332 . The case inner chamber 321, the pilot chamber 111 and the pressure chamber 191 shown in FIG. 3 communicate with the piston rod passage portion 46, and are always communicated with the lower chamber 20 via the introduction orifice 212 shown in FIG. .

The extension-side second damping force generating mechanism 333 is fixed so that the upper chamber 19 and the lower chamber 20 are communicated with each other even when the second valve seat 281 and the sub-valve 331 contacting the second valve seat 281 are in contact with each other. No orifice is formed. That is, the extension-side second damping force generating mechanism 333 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other when the second valve seat 281 and the sub-valve 331 are in contact with each other over the entire circumference. In other words, the second passage 332 does not have a fixed orifice that always communicates the upper chamber 19 and the lower chamber 20, and thus the second passage 332 always communicates the upper chamber 19 and the lower chamber 20. is not.

As shown in FIG. 2, the extension-side second passage 332 that communicates between the upper chamber 19 and the lower chamber 20 is the extension-side first passage that similarly communicates between the upper chamber 19 and the lower chamber 20. 75, and the first damping force generating mechanism 41 is generated in one of the parallel first passage 75 and the second passage 332, and the second damping force is generated in the other second passage 332. A mechanism 333 is provided respectively. Therefore, both the first damping force generating mechanism 41 and the second damping force generating mechanism 333 on the rebound side are arranged in parallel.

As shown in FIG. 4 , the outer peripheral side of the outer annular portion 291 of the disc valve 247 including the outer peripheral contact/disconnection portion 301 constitutes a sub-valve 341 that can be seated on and removed from the first valve seat 271 . The sub-valve 341 is provided on the upper chamber 19 side of the upper chamber 19 and the lower chamber 20 .

By separating the sub-valve 341 from the first valve seat 271, the case inner chamber 321 and the upper chamber 19 are communicated with each other through the gap between the first valve seat 271 and the lower chamber 20. It communicates with the upper chamber 19 . At this time, the sub-valve 341 suppresses the flow of oil between itself and the first valve seat 271 to generate a damping force. The sub-valve 341 is a discharge valve that opens when the oil is discharged from the case inner chamber 321 to the upper chamber 19 through the gap between the first valve seat 271 and the oil from the upper chamber 19 to the case inner chamber 321. Inflow of the oil through the gap with the first valve seat 271 is restricted.

passages in the plurality of passage holes 39 of the piston 18 and in the annular groove 40, the introduction orifices 212 of the disc 201, the passages in the large diameter hole portion 45 of the piston 18, the piston rod passage portion 46 of the piston rod 21, The passage in the large-diameter hole 277 of the case member 248 and the passage groove 272, the case inner chamber 321, and the passage between the sub-valve 341 and the first valve seat 271 appearing when the valve is opened form the lower chamber of the piston 18. A second passage 342 is formed through which oil flows from the lower chamber 20 on the upstream side in the cylinder 2 to the upper chamber 19 on the downstream side by movement to the 20 side.

The second passage 342 serves as a contraction-side passage through which oil flows from the lower chamber 20 on the upstream side toward the upper chamber 19 on the downstream side during the movement of the piston 18 toward the lower chamber 20 side, that is, the compression stroke. The second passageway 342 includes a check valve 195 that opens during the compression stroke of the frequency sensitive mechanism 121 shown in FIG. The second passage 342 is a passage in the large-diameter hole portion 93 of the case member 55 communicating with the piston rod passage portion 46 , the orifice 112 of the disk 56 , the pilot chamber 111 , and the housing 122 communicating with the piston rod passage portion 46 . , an orifice 193 , a pressure chamber 191 , a passage of a check valve 195 appearing when the valve is opened, a communication chamber 192 , and a communication passage 185 . The partition disk 124 that constitutes the check valve 195 blocks the flow of oil from the pressure chamber 191 to the communication chamber 192 in the second passage 332 on the extension side, which is one of the second passages 332 and 342, and the contraction on the other side. It is configured to allow oil to flow from the communication chamber 192 to the pressure chamber 191 in the second passage 342 on the side. Therefore, the frequency sensitive mechanism 121 performs frequency sensitive operation only in the extension stroke, and the frequency sensitive function is canceled in the contraction stroke.

Note that the partition disk 124 may be set so as to always block the flow of oil between the pressure chamber 191 and the communication chamber 192 regardless of the pressure states of the pressure chamber 191 and the communication chamber 192 . In other words, the partition disc 124 may block flow in both directions between the pressure chamber 191 and the communication chamber 192 . In other words, the partition disk 124 should block the flow of working fluid in at least one direction between the pressure chamber 191 and the communication chamber 192 .

Like the second passage 332, the second passage 342 includes the piston rod passage portion 46 in the passage notch portion 30 formed by notching the piston rod 21. It is formed by notching. Instead of forming the piston rod 21 by notching it, the piston rod passage portion 46 may be formed by penetrating the inside of the piston rod 21 in the form of a hole, as described above. In other words, the second passage 342 may include the piston rod passage portion 46 formed by notching or penetrating the piston rod 21 .

As shown in FIG. 4, a sub-valve 341 and an annular first valve seat 271 formed on the outer tubular portion 262 of the case member 248 are provided in a second passage 342 on the compression side. A compression-side second damping force generating mechanism 343 is configured that opens and closes and suppresses the flow of oil from the second passage 342 to the upper chamber 19 to generate a damping force. In other words, the second damping force generating mechanism 343 has the first valve seat 271 provided on the case member 248 . The sub-valve 341 that constitutes the second damping force generating mechanism 343 on the compression side is a sub-valve on the compression side. A second damping force generating mechanism 343 consisting of a sub-valve 341 and a first valve seat 271 has the piston rod 21 inserted radially inward, and is one of the two upper and lower chambers 19 and 20 in the second passage 342. It is arranged on one upper chamber 19 side.

As shown in FIG. 2, the very low speed valve mechanism 231 having the second damping force generating mechanisms 333 and 343 and the frequency sensitive mechanism 121 are arranged in the upper chamber 19, and the frequency sensitive mechanism 121 is arranged in the upper chamber 19. It is arranged in the lower chamber 20 . In other words, the extremely low speed valve mechanism 231 is arranged on the upper chamber 19 side of the piston 18 and the frequency sensitive mechanism 121 is arranged on the lower chamber 20 side of the piston 18 .

In the second passage 342, when the second damping force generating mechanism 343 is in the open state, the introduction orifice 212 in the notch 211 of the disk 201 shown in FIG. The second passage 342 is also throttled. The introduction orifice 212 is common to the second passages 332,342. The introduction orifice 212 is arranged on the upstream side of the sub-valve 341 when the sub-valve 341 is opened and the oil flows through the second passage 342 . In other words, the introduction orifice 212 is arranged closer to the lower chamber 20 than the sub-valve 341 in the second passage 342 . The introduction orifice 212 is formed by cutting out a disk 201 that is one of the parts that make up the compression-side first damping force generating mechanism 42 and contacts the piston 18 .

The second damping force generating mechanism 343 on the compression side is fixed to allow communication between the upper chamber 19 and the lower chamber 20 even when the first valve seat 271 and the sub-valve 341 contacting the first valve seat 271 are in contact with each other. No orifice is formed. That is, the compression-side second damping force generating mechanism 343 does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other when the first valve seat 271 and the sub-valve 341 are in contact with each other over the entire circumference. In other words, the second passage 342 does not have a fixed orifice that always communicates the upper chamber 19 and the lower chamber 20, so the second passage 342 always communicates the upper chamber 19 and the lower chamber 20. is not.

As shown in FIG. 2, the frequency sensitive mechanism 121 includes a housing 122 provided at the common portion of the second passages 332 and 342, and a housing 122 provided in the housing 122 extending from the common portion of the second passages 332 and 342 to one side. A compartment disk 124 defining a chamber 19 side and a lower chamber 20 side on the other side and forming a pressure chamber 191 in the housing 122 is provided.

In the shock absorber 1, at least in the axial direction of the oil flow in the piston 18, the upper chamber 19 and the lower chamber 20 are composed of the first damping force generating mechanisms 41, 42 and the second damping force generating mechanism 333, 343 only. Therefore, the shock absorber 1 is not provided with a fixed orifice that constantly communicates between the upper chamber 19 and the lower chamber 20 at least on the passage of oil that passes through the piston 18 in the axial direction.

The second passage 342 on the contraction side, which communicates between the upper chamber 19 and the lower chamber 20, is composed of a first passage 222, which is a passage on the contraction side, which similarly communicates between the upper chamber 19 and the lower chamber 20, and the lower chamber 20 side. The first passage 222 and the second passage 342 are arranged in parallel except for the passages in the plurality of passage holes 39 and the annular groove 40 , and the first passage 222 has the first damping force generating mechanism 42 in the parallel portion of the first passage 222 and the second passage 342 . However, a second damping force generating mechanism 343 is provided in each of the second passages 342 . Therefore, both the first damping force generating mechanism 42 and the second damping force generating mechanism 343 on the compression side are arranged in parallel.

As described above, the second damping force generating mechanisms 333 and 343 of the extremely low-speed valve mechanism 231 are, as shown in FIG. an annular first valve seat 271 formed on the outer cylindrical portion 262 of the disk valve 247, an annular disk valve 247 having an outer peripheral side contact portion 301 disposed on the first valve seat 271 so as to be separable, and a disc The first valve seat 271 is provided on the opposite side of the first valve seat 271 in the axial direction of the valve 247 and detachably supports the inner peripheral side contact portion 302 radially inside the outer peripheral side contact portion 301 of the disc valve 247 . 2 valve seats 281 and . The second damping force generating mechanism 333 is provided at the end of the second passage 332 on the upper chamber 19 side, and the second damping force generating mechanism 343 is located at the end of the second passage 342 on the upper chamber 19 side. is provided in

As shown in FIG. 1, the above-described base valve 25 is provided between the bottom member 12 of the outer cylinder 4 and the inner cylinder 3 . The base valve 25 includes a base valve member 351 that separates the lower chamber 20 and the reservoir chamber 6 , a disk 352 provided on the lower side of the base valve member 351 , that is, on the reservoir chamber 6 side, and an upper side of the base valve member 351 , that is, on the lower side of the base valve member 351 . It has a disc 353 provided on the chamber 20 side and mounting pins 354 for mounting the discs 352 and 353 to the base valve member 351 .

The base valve member 351 has an annular shape, and a mounting pin 354 is inserted through the center in the radial direction. The base valve member 351 has a plurality of passage holes 355 through which oil can flow between the lower chamber 20 and the reservoir chamber 6. A plurality of passage holes 356 are formed between the chamber 20 and the reservoir chamber 6 to allow the oil to flow. The disk 352 on the reservoir chamber 6 side allows the oil to flow from the lower chamber 20 to the reservoir chamber 6 through the passage hole 355, while allowing the oil to flow from the reservoir chamber 6 to the lower chamber 20 through the passage hole 355. restrain the flow. The disk 353 allows oil to flow from the reservoir chamber 6 to the lower chamber 20 through the passage hole 356 , while suppressing oil from flowing from the lower chamber 20 to the reservoir chamber 6 through the passage hole 356 .

The disk 352, together with the base valve member 351, constitutes a compression-side damping valve mechanism 357 that opens during the compression stroke of the shock absorber 1 to flow oil from the lower chamber 20 to the reservoir chamber 6 and generate damping force. ing. The disk 353 and the base valve member 351 constitute a suction valve mechanism 358 that opens during the extension stroke of the shock absorber 1 to allow oil to flow from the reservoir chamber 6 into the lower chamber 20 . In addition, the suction valve mechanism 358 supplies oil from the reservoir chamber 6 to the lower chamber 20 without substantially generating a damping force so as to compensate for the shortage of the oil caused mainly by the extension of the piston rod 21 from the cylinder 2. perform the function of flushing.

As shown in FIG. 2, an extremely low speed valve mechanism 231, a main valve 221, a piston 18, a main valve 65, a case member 55, a hard valve 110, a frequency sensitive mechanism 121, etc. are assembled to the mounting shaft portion 28 of the piston rod 21. , a nut 361 is screwed onto the male thread 31 of the mounting shaft portion 28 . As a result, the nut 361 and the shaft stepped portion 29 of the piston rod 21 , except for the partition disc 124 of the frequency sensitive mechanism 121 , move the extremely low-speed valve mechanism 231 , the main valve 221 , the piston 18 , the main valve 65 , the case member 55 and the hardware. At least the inner peripheral sides of the valve 110, the frequency sensitive mechanism 121, etc. are axially clamped.

In such an attached state, the disc valve 247 and the discs 244 to 246 constituting the second valve seat 281 of the extremely low speed valve mechanism 231 are clamped on the disc 243 and the inner cylindrical portion 263 of the case member 248 at their inner peripheral sides. be done. At this time, the disk valve 247 is clamped at the inner annular portion 292 as shown in FIG. 4, and the support portion 293 and the outer annular portion 291 shown in FIG. 5 are not clamped. At the same time, as shown in FIG. 4 , the sub-valve 331 of the outer annular portion 291 of the disc valve 247 abuts against the second valve seat 281 over the entire circumference from the piston 18 side at the inner peripheral side contact portion 302 , and the outer annular portion The sub-valve 341 of 291 abuts on the first valve seat 271 at the outer peripheral contact/contact portion 301 from the side opposite to the piston 18 over the entire circumference.

Here, from the relationship between the axial positions of the first valve seat 271 and the second valve seat 281 and the thickness of the disk valve 247, the outer annular portion 291 that contacts the first valve seat 271 and the second valve seat 281 at the same time is , and deforms in a tapered shape so as to move away from the piston 18 in the axial direction as it goes radially outward. In other words, in the outer annular portion 291 , the outer circumferential separation portion 301 that contacts the first valve seat 271 is axially opposite to the piston 18 than the inner circumference separation portion 302 that contacts the second valve seat 281 . It is deformed into a tapered shape so that it is positioned on the side.

In this attached state, the inner peripheral side of the main valve 221 is clamped between the disk 204 and the portion radially inside the annular groove 40 of the piston 18 via the disk 201, and the inner peripheral side of the main valve 221 is clamped from the annular groove 40 of the piston 18. also contacts the radially outer valve seat 48 over the entire circumference.

In this attached state, as shown in FIG. 2, the inner peripheral side of the main valve 65 is clamped between the disk 53 and the portion radially inside the annular groove 38 of the piston 18 via the disk 50. The disk 51 abuts on the valve seat 47 radially outside the annular groove 38 of the piston 18 over the entire circumference.

In this attached state, the hard valve 110 is clamped on the inner peripheral side between the inner cylindrical portion 82 of the case member 55 and the disc 61 via the disc 56, and the disc 57 is attached to the valve seat 84 of the case member 55. It abuts all around.

In this attached state, as shown in FIG. 3, the partition disc 124 abuts against the support portion 147 of the housing 122 and the disc 125 along the entire circumference of the disc 161 .

A hydraulic circuit diagram of the shock absorber 1 described above is as shown in FIG. That is, the main valve 65 of the first damping force generating mechanism 41 is provided in the extension-side first passage 75 connecting the upper chamber 19 and the lower chamber 20 , and the compression-side first passage 75 connecting the lower chamber 20 and the upper chamber 19 is provided. A main valve 221 of the first damping force generating mechanism 42 is provided in the passage 222 . A sub-valve 331 of a second damping force generating mechanism 333 is provided in a second passage 332 on the expansion side connecting the upper chamber 19 and the lower chamber 20, and a second passage on the contraction side connecting the lower chamber 20 and the upper chamber 19 is provided. A sub-valve 341 of the second damping force generating mechanism 343 is provided at 342 . In addition, an introduction orifice 212 is provided in a passage that connects the piston rod passage portion 46, which is a common portion of the second passage 332 and the second passage 342, and the portion of the first passage 222 that always communicates with the lower chamber 20, and the piston rod passage. An orifice 193 is provided in a passage connecting the portion 46 and the pressure chamber 191 . A check valve 195 is provided in a passage connecting the pressure chamber 191 and the lower chamber 20, and connects the pilot chamber 111, which applies back pressure to the main valve 65 of the first damping force generating mechanism 41, and the piston rod passage portion 46. An orifice 112 is provided in the passageway. A hard valve 110 of the first damping force generating mechanism 41 is provided between the pilot chamber 111 and the lower chamber 20 .

The shock absorber 1 has the main valve 65 and the hard valve 110 of the first damping force generating mechanism 41, the main valve 221 of the first damping force generating mechanism 42, the second The hydraulic fluid does not flow from the upper chamber 19 side to the lower chamber 20 unless both the sub-valve 331 of the damping force generating mechanism 333 and the sub-valve 341 of the second damping force generating mechanism 343 are opened. The shock absorber 1 is designed to set the orifice characteristics in the normal low speed region by the introduction orifice 212 leading from the piston rod passage portion 46 to the lower chamber 20 . In other words, as shown in FIG. 4, the shock absorber 1 has a disk 201 having a notch 211 located closest to the piston body 35 on the upper chamber 19 side. set. The shock absorber 1 becomes an ordinary piston valve and becomes orificeless in the compression stroke. The shock absorber 1 also has a flow path from the lower chamber 20 to the upper chamber 19 through the introduction orifice 212 , the piston rod passage portion 46 and the extremely low speed valve mechanism 231 .

Of the first damping force generating mechanism 42 and the second damping force generating mechanism 343 on the compression side, the main valve 221 of the first damping force generating mechanism 42 is constructed by laminating a plurality of discs 202 and 203. Therefore, the rigidity and the valve opening pressure are higher than those of the sub-valve 341 of the second damping force generating mechanism 343 composed of one disc valve 247 . Therefore, in the compression stroke, when the piston speed is lower than the predetermined value, the second damping force generating mechanism 343 is opened while the first damping force generating mechanism 42 is closed, and the piston speed is reduced to this predetermined value. In the above normal speed range, both the first damping force generating mechanism 42 and the second damping force generating mechanism 343 are opened. The sub-valve 341 is an extremely low-speed valve that opens to generate a damping force when the piston speed is extremely low.

That is, in the compression stroke, as the piston 18 moves toward the lower chamber 20, the pressure in the lower chamber 20 increases and the pressure in the upper chamber 19 decreases. Since neither of the damping force generating mechanisms 333, 343 has a fixed orifice that communicates the lower chamber 20 with the upper chamber 19, oil does not flow until the second damping force generating mechanism 343 is opened. Therefore, the damping force rises sharply. In a region where the piston speed is higher than the first predetermined value at which the second damping force generating mechanism 343 opens, and is lower than the second predetermined value, which is higher than the first predetermined value and lower than the second predetermined value, the second While the first damping force generating mechanism 42 is closed, the second damping force generating mechanism 343 is opened, and oil flows from the lower chamber 20 to the upper chamber 19 through the second passage 342 .

That is, the sub-valve 341 is separated from the first valve seat 271, and the lower chamber 20 and the upper chamber 19 are communicated with each other through the second passage 342 on the contraction side. Therefore, the oil in the lower chamber 20 flows through the passages in the plurality of passage holes 39 and the annular groove 40 of the piston 18 and the introduction orifice 212 to the piston in the passage cutout 30 of the piston rod 21. On the other hand, from the communication passage 185 and the communication chamber 192 of the frequency sensitive mechanism 121 shown in FIG. flow to 4, the case inner chamber 321, the sub-valve 341 of the second damping force generating mechanism 343, and the second damping force generating mechanism 343. 1 into the upper chamber 19 via passages between the valve seats 271 . As a result, a damping force with valve characteristics (a characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in an extremely low speed range in which the piston speed is lower than the second predetermined value. At this time, the pressure loss caused by the introduction orifice 212 and the orifice 193 provided in series with the second damping force generating mechanism 343, which occurs when the piston speed increases, determines the slope of the damping force in the extremely low speed region.

In the compression stroke, the first damping force generating mechanism 42 opens while the second damping force generating mechanism 343 remains open in the normal speed region where the piston speed is equal to or higher than the second predetermined value. In other words, the sub-valve 341 is separated from the first valve seat 271 in the same manner as described above, and oil flows from the lower chamber 20 to the upper chamber 19 through the second passage 342 on the contraction side. Leaving the seat 48, oil flows from the lower chamber 20 to the upper chamber 19 also in the first passage 222 on the contraction side. Therefore, in addition to the second passage 342 , the oil in the lower chamber 20 passes through passages in the plurality of passage holes 39 and the annular groove 40 that constitute the first passage 222 and passages between the main valve 221 and the valve seat 48 . and flows through. As a result, even in the normal speed region where the piston speed is equal to or higher than the second predetermined value, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) can be obtained. The increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region is lower than the increase rate of the compression damping force with respect to the increase in piston speed in the extremely low speed region. In other words, the slope of the increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region can be flatter than in the extremely low speed region.

As described above, in the shock absorber 1, the passage for flowing oil from the lower chamber 20 to the upper chamber 19 in the compression stroke is provided in parallel with the first passage 222 and the second passage 342, and the main valve 221 and the sub valve 341 are arranged in parallel. is provided. Also, the introduction orifice 212 and the orifice 193 are connected in series with the sub-valve 341 in the second passage 342 .

In addition, in the compression stroke, the damping force characteristic of the damping valve mechanism 357 of the base valve 25 is also combined.

Of the first damping force generating mechanism 41 shown in FIG. 3 and the second damping force generating mechanism 333 shown in FIG. Since the pilot discs 52 are laminated, the rigidity is higher than that of the sub-valve 331 of the second damping force generating mechanism 333 composed of one disc valve 247, and the valve opening pressure is higher. Therefore, in the extension stroke, the second damping force generating mechanism 333 is opened while the first damping force generating mechanism 41 is closed in an extremely low speed region in which the piston speed is lower than a predetermined value. Also, in the normal speed range where the piston speed is equal to or higher than this predetermined value, both the first damping force generating mechanism 41 and the second damping force generating mechanism 333 are opened. The sub-valve 331 is an extremely low-speed valve that opens to generate a damping force when the piston speed is extremely low.

That is, in the extension stroke, as the piston 18 moves toward the upper chamber 19, the pressure in the upper chamber 19 increases and the pressure in the lower chamber 20 decreases. Since neither of the damping force generating mechanisms 333, 343 has a fixed orifice that communicates the upper chamber 19 with the lower chamber 20, oil does not flow until the second damping force generating mechanism 333 is opened. Therefore, the damping force rises sharply in the extension stroke when the piston speed is less than the third predetermined value. In addition, in a region where the piston speed is higher than the third predetermined value at which the second damping force generating mechanism 333 opens, and is lower than the fourth predetermined value, which is higher than the third predetermined value, it is extremely low speed region. , the first damping force generating mechanism 41 is closed, and the second damping force generating mechanism 333 is opened.

That is, the sub-valve 331 is separated from the second valve seat 281, and the upper chamber 19 and the lower chamber 20 are communicated with each other through the second passage 332 on the extension side. Therefore, the oil in the upper chamber 19 flows through the passage between the open sub-valve 331 and the second valve seat 281 , which constitutes the second passage 332 , the outer annular portion 291 and the inner annular portion 292 of the disc valve 247 . a passage between, a case inner chamber 321, passages in the passage groove 272 and the large diameter hole portion 277 of the case member 248, the piston rod passage portion 46 of the piston rod 21, and the large diameter hole portion 45 of the piston 18 It flows into the lower chamber 20 via passages therein, the introduction orifice 212 and passages in the annular groove 40 of the piston 18 and in the plurality of passage holes 39 . As a result, even in an extremely low speed region in which the piston speed is lower than the fourth predetermined value, a damping force with a valve characteristic (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained. At this time, the pressure loss caused by the introduction orifice 212 provided in series with the second damping force generating mechanism 333, which occurs when the piston speed increases, determines the slope of the damping force in the extremely low speed region.

Further, in the extension stroke, in the normal speed range where the piston speed is equal to or higher than the fourth predetermined value, the first damping force generating mechanism 41 opens while the second damping force generating mechanism 333 remains open. In other words, the sub-valve 331 is separated from the second valve seat 281 , and oil flows from the upper chamber 19 to the lower chamber 20 through the extension-side second passage 332 , and the main valve 65 is separated from the valve seat 47 . While sitting down, oil is allowed to flow from the upper chamber 19 to the lower chamber 20 through the first passage 75 on the extension side. Therefore, in addition to the second passage 332 , the oil in the upper chamber 19 passes through passages within the plurality of passage holes 37 of the first passage 75 and the annular groove 38 and passages between the main valve 65 and the valve seat 47 . flows into the lower chamber 20 via the .

At this time, the opening pressure of the main valve 65 changes according to the pressure in the pilot chamber 111 forming part of the second passage 332 . That is, when the input to the piston rod 21 has a low frequency and a large stroke, oil flows into the pressure chamber 191 of the frequency sensitive mechanism 121 forming a part of the second passage 332, and the volume of the pressure chamber 191 increases. However, the deformation of the partition disk 124 is then restricted by the stopper member 127 . Therefore, when the hydraulic fluid tries to flow further into the pressure chamber 191, the pressure in the pressure chamber 191 increases, the pressure in the pilot chamber 111 forming part of the second passage 332 also increases, and the opening pressure of the main valve 65 also increases. It rises and becomes a hard damping force characteristic.

On the other hand, when the input to the piston rod 21 has a high frequency and a small stroke, oil flows into the pressure chamber 191 forming part of the second passage 332, and the volume of the pressure chamber 191 increases. Although the partition disk 124 is deformed, the amount of deformation is small. Therefore, the partition disk 124 is not restricted by the stopper member 127 and is deformed by the amount of the fluid flowing into the pressure chamber 191 . As a result, the pressure in the pressure chamber 191 does not rise, and therefore the pressure in the pilot chamber 111 does not rise either, so the valve opening pressure of the main valve 65 is low, resulting in soft damping force characteristics.

Patent Literature 1 described above describes a shock absorber having two valves that open in the same stroke. By having two valves that open in the same stroke, one valve can be opened in a region where the piston speed is lower than the other valve, and both valves can be opened in a region where the piston speed is higher than this. It becomes possible. With such a shock absorber, a damping force of a valve characteristic (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained from a region where the piston speed is low. In such shock absorbers, there is a demand to make the damping force variable depending on the frequency.

The shock absorber 1 of the first embodiment has a first passage 75 through which the working fluid moves from the upper chamber 19 on the upstream side in the cylinder 2 to the lower chamber 20 on the downstream side due to the movement of the piston 18 in the extension stroke, for example. The second passages 332 are provided in parallel, and the first damping force generating mechanism 41 is provided in the first passage 75 and the second damping force generating mechanism 333 is provided in the second passage 332 . In a region where the piston speed is low, the first damping force generation mechanism 41 is closed and the second damping force generation mechanism 333 is opened. Both the generating mechanism 41 and the second damping force generating mechanism 333 are configured to open. As a result, it is possible to obtain the damping force of the valve characteristic from the region where the piston speed is low.

In addition, the shock absorber 1 of the first embodiment includes a housing 122 and a second passage 332 provided inside the housing 122 that defines the upper chamber 19 side and the lower chamber 20 side to form a pressure chamber 191 in the housing 122 . A frequency sensitive mechanism 121 is provided with a dividing disc 124 forming. This makes it possible to make the damping force variable depending on the frequency.

That is, the shock absorber 1 can generate a very low speed damping force by providing the very low speed valve mechanism 231, and furthermore, by providing the frequency sensitive mechanism 121, it is possible to provide a frequency sensitive function. Since the introduction orifice 212 is provided, it is possible to suppress the flow of the oil to the frequency sensitive mechanism 121 in the extremely low piston speed region where the oil passes through the introduction orifice 212 relatively smoothly. The valve characteristics can be exhibited regardless of the In addition, in a high piston speed range where the oil cannot smoothly pass through the introduction orifice 212, the oil flows to the frequency sensitive mechanism 121, and frequency dependence can be exhibited.

By attaching the very low speed valve mechanism 231, the vehicle equipped with the shock absorber 1 has a smooth ride comfort and straight running stability when the steering is slightly steered and when the vehicle is traveling on a smooth road. improves. In addition, when the piston speed increases, it becomes a soft damping force characteristic against the input of high frequency and small stroke, that is, the input of high frequency vibration that deteriorates the ride comfort. For low-frequency, large-stroke input, the damping force characteristics become hard, suppressing sprung behavior and stabilizing it, and improving the sense of stability against sudden steering.

FIG. 7 shows a Lissajous waveform representing the relationship between the stroke and the damping force obtained when the shock absorber 1 of the first embodiment is vibrated. In FIG. 7, as indicated by A1, a soft damping force characteristic is provided for high-frequency vibration input, and a hard damping force characteristic is provided for low-frequency vibration input. It can be seen that the force is variable.

FIG. 8 is a characteristic diagram showing the relationship between frequency and damping force obtained when the shock absorber 1 of the first embodiment is vibrated. In FIG. 8 as well, as indicated by A2, the damping force characteristics are soft for high-frequency vibration input, and hard for low-frequency vibration input. It can be seen that the damping force is variable.

FIG. 9 is a Lissajous waveform showing the relationship between the stroke and the damping force obtained when the shock absorber 1 of the first embodiment is vibrated, showing the high frequency vibration X1 and the low frequency vibration X2 superimposed. is. As shown in FIG. 9, there is a soft damping force characteristic for the high frequency vibration X1, and a hard damping force characteristic for the low frequency vibration X2, and the damping force becomes variable depending on the frequency. I understand.

FIG. 10 shows the relationship between the piston speed and the damping force obtained when the shock absorber 1 of the first embodiment is vibrated, and shows the high frequency vibration X3 and the low frequency vibration X4 superimposed. is. From FIG. 10, as shown in A3, while suppressing the change due to the frequency of the damping force at extremely low speed by the high frequency vibration X3 and the low frequency vibration X4, as shown in A4, in the region where the piston speed is in the low speed range or higher, It can be seen that the damping force can be switched between soft and hard between the high frequency vibration X3 with a high piston speed and the low frequency vibration X4 with a low piston speed.

Also, in the shock absorber 1 of the first embodiment, the second damping force generating mechanism 333 is arranged in the upper chamber 19 on the upstream side in the extension stroke, and the frequency sensitive mechanism 121 is arranged in the lower chamber 20 on the downstream side in the extension stroke. Because of the arrangement, the communication chamber 192 can be configured to always communicate with the lower chamber 20 . Therefore, the frequency sensitive mechanism 121 can be configured compactly.

In addition, the shock absorber 1 of the first embodiment can be configured compactly because the second passages 332 and 342 have the piston rod passage portion 46 formed by notching or penetrating the piston rod 21. .

The shock absorber 1 of the first embodiment has two first damping force generating mechanisms 41 and a second damping force generating mechanism 333 that open during the extension stroke, and two first damping force generating mechanisms that open during the contraction stroke. It has the mechanism 42 and the second damping force generating mechanism 343 . Even with such a configuration, the second damping force generating mechanisms 333 and 343 are formed in the outer cylindrical portion 262 of the bottomed cylindrical case member 248 having the bottom portion 261 and the outer cylindrical portion 262 . 1 valve seat 271, an annular disc valve 247 in which the outer peripheral side separating/contacting portion 301 on the outer peripheral side is detachably arranged on the first valve seat 271 of the case member 248, and the first valve seat 271 of the disc valve 247. and a second valve seat 281 which is provided on the opposite side of the disk valve 247 and which detachably supports the inner peripheral side contact portion 302 radially inner than the outer peripheral side contact portion 301 of the disk valve 247 . there is Therefore, the structure can be simplified, and the number of parts can be reduced and the length in the axial direction can be suppressed.

The disc valve 247 constituting the second damping force generating mechanisms 333 and 343 has an outer annular portion 291 which is detachably arranged on the first valve seat 271 and the second valve seat 281, and the piston rod 21 is inserted therethrough. Since it has an inner annular portion 292 fixed to the piston rod 21 and a support portion 293 connecting them, the outer annular portion 291 opens and closes in contact with the first valve seat 271 and the second valve seat 281. While suppressing the radial displacement of the inner annular portion 292 and the support portion 293, the outer annular portion 291 can be operated in substantially the same manner as a free valve that is not connected to other portions.

[Second embodiment]
Next, the second embodiment will be described mainly with reference to FIGS. 11 and 12, focusing on differences from the first embodiment. Parts common to those of the first embodiment are denoted by the same designations and the same reference numerals.

As shown in FIG. 11, the shock absorber 1A of the second embodiment has a piston rod 21A that is partially different from the piston rod 21 of the first embodiment. The piston rod 21A has a mounting shaft portion 28A having a shorter axial length than the mounting shaft portion 28. As shown in FIG. A passage cutout portion 30A having a length in the axial direction of the piston rod 21A shorter than that of the passage cutout portion 30 is formed in the mounting shaft portion 28A. Therefore, the piston rod 21A has a piston rod passage portion 46A whose axial length is shorter than that of the piston rod passage portion 46. As shown in FIG.

Moreover, in the shock absorber 1A, the configuration between the piston 18 and the nut 361 is different from that of the first embodiment. That is, on the valve seat 47 side of the piston 18, one disc 400, one disc 401, one pilot disc 52A, and a plurality of discs (specifically, 5 discs 403, one spring disc 404, one disc 405, one housing 55A, a plurality of (specifically four) discs 407, and one disc 408. , one disk 409 and one annular member 410 are provided by fitting the mounting shaft portion 28A of the piston rod 21A to the inside thereof.

Disks 400, 401, 403, 405, 407-409, spring disk 404, housing 55A and annular member 410 are all made of metal. Each of the discs 400, 401, 403, 405, 407-409 and the annular member 410 is in the form of a perforated circular flat plate having a constant thickness into which the mounting shaft portion 28A of the piston rod 21A can be fitted. The spring disc 404, the pilot disc 52A and the housing 55A all have an annular shape in which the mounting shaft portion 28A of the piston rod 21A can be fitted.

The housing 55A has a bottomed tubular shape and an annular shape, and is formed with a through hole 80A penetrating in the thickness direction at the center in the radial direction. The housing 55A includes a perforated disc-shaped bottom portion 81A (first bottom portion), a cylindrical inner cylindrical portion 82A protruding from the inner peripheral edge portion of the bottom portion 81A to both sides along the axial direction of the bottom portion 81A, and a bottom portion. A cylindrical outer cylindrical portion 83A (first cylindrical portion) protruding to one side along the axial direction of the bottom portion 81A from the outer peripheral edge portion of the bottom portion 81A, and a radially intermediate position of the bottom portion 81A extending from the axial direction of the bottom portion 81A. and an annular valve seat 84A projecting in the direction opposite to the outer cylindrical portion 83A. The amount of protrusion of the outer cylindrical portion 83A from the bottom portion 81A is greater than the amount of protrusion of the inner cylindrical portion 82A on the side of the outer cylindrical portion 83A. The housing 55A allows the mounting shaft portion 28A of the piston rod 21A to pass through the through hole 80A on the inner peripheral side of the inner cylindrical portion 82A.

As shown in FIG. 12, the bottom portion 81A is formed with a disk contact portion 432 having a flat annular seat surface 431 perpendicular to the central axis on the axial and radial outer cylindrical portion 83A side. It is An annular recess 434 having a stopper surface 433 axially recessed from the seat surface 431 is formed at a radially intermediate position of the disc contact portion 432 . The concave portion 434 has a shape in which the width in the radial direction becomes narrower as the depth increases. The cross section of the stopper surface 433 on a plane including the central axis of the bottom portion 81A has a constant circular arc shape regardless of the position in the circumferential direction.

In the bottom portion 81A, a tapered portion 436 having a tapered surface 435 whose height from the seat surface 431 becomes higher toward the radially inner side than the radial disk contact portion 432 on the axially outer cylindrical portion 83A side. is formed. The tapered portion 436 is provided at the radial end portion of the bottom portion 81A on the inner cylindrical portion 82A side. The bottom portion 81A, the inner cylindrical portion 82A, the outer cylindrical portion 83A, the valve seat 84A, the disk contact portion 432, the concave portion 434, and the tapered portion 436 are arranged coaxially, and their central axes are aligned with the center of the housing 55A. axis line.

A through hole 437 is formed in the bottom portion 81A at the deepest bottom position of the recessed portion 434, that is, at the center position of the width of the recessed portion 434 in the radial direction. A plurality of through holes 437 are formed in the bottom portion 81A at intervals in the circumferential direction of the bottom portion 81A. At least one through hole 437 may be provided in the bottom portion 81A. The through hole 437 is arranged outside the valve seat 84A in the radial direction of the bottom portion 81A.

An annular partition disk 124A (partition member) is provided in the housing 55A so as to face the bottom portion 81A. The partition disk 124A is a flat plate made of metal, and has an outer diameter slightly smaller than the maximum diameter of the seat surface 431 of the disk contact portion 432, in other words, the inner diameter of the outer cylindrical portion 83A and the maximum diameter of the stopper surface 433. Its inner diameter is slightly larger than the minimum diameter of the seat surface 431 of the disc contact portion 432 and smaller than the minimum diameter of the stopper surface 433 . As a result, the partition disk 124A is guided by the outer cylindrical portion 83A so as to restrict movement in the radial direction and is movable in the axial direction. It's becoming A mounting shaft portion 28A of the piston rod 21A is passed through the partition disk 124A.

A through hole 437 formed at the deepest position of the recessed portion 434 of the bottom portion 81A is provided so as to face the division disk 124A in the radial direction and face the axial direction. The partition disk 124</b>A closes the through hole 437 by making surface contact with the seat surface 431 and opens the through hole 437 by separating from the seat surface 431 . In addition, the partition disk 124A is elastically deformable so as to enter the recess 434, and at that time, it comes into contact with the boundary peripheral edge portions on both sides in the radial direction between the stopper surface 433 and the seat surface 431, or the entire surface of the stopper surface 433. to maintain the closed state of the through hole 437 .

A through hole 438 is formed in the bottom portion 81A at an intermediate position in the radial direction of the tapered portion 436 so as to pass through the housing 55A along the axial direction. A plurality of through holes 438 are formed at intervals in the circumferential direction of the bottom portion 81A. At least one through hole 438 may be provided in the bottom portion 81A. The through hole 438 is arranged between the valve seat 84A and the inner cylindrical portion 82A in the radial direction of the bottom portion 81A. Thereby, the through hole 438 is provided inside the through hole 437 in the radial direction of the housing 55A, that is, in the radial direction of the bottom portion 81A.

The through-hole 80A on the inner circumference of the inner cylindrical portion 82A has a small-diameter hole portion 92A on the side of the axial valve seat 84A, into which the mounting shaft portion 28A of the piston rod 21A is fitted. A large-diameter hole portion 93A having a larger diameter than the small-diameter hole portion 92A is provided on the side opposite to 84A. A part of the mounting shaft portion 28A, which axially penetrates the inner cylindrical portion 82A and extends to both sides, is arranged in the housing 55A in the axial direction.

The disc 400 has an outer diameter smaller than the inner diameter of the tip surface of the valve seat 47 . The disk 401 has an outer diameter larger than the outer diameter of the tip surface of the valve seat 47 of the piston 18 . The disc 401 can contact the valve seat 47 , and opens and closes the opening of the passage in the annular groove 38 and the passage hole 37 formed in the piston 18 by separating and contacting the valve seat 47 .

The pilot disk 52A is composed of a metal disk 71A and a rubber seal member 72A fixed to the disk 71A. The disk 71A has a perforated circular flat plate shape with a constant thickness in which the mounting shaft portion 28A of the piston rod 21A can be fitted. . The seal member 72A is fixed to the outer peripheral side of the disk 71A opposite to the piston 18 and has an annular shape. In other words, the pilot disk 52A has an annular seal member 72A on its outer periphery.

The seal member 72A is slidably and liquid-tightly fitted over the entire circumference of the inner peripheral surface of the outer cylindrical portion 83A of the housing 55A, and constantly seals the gap between the pilot disk 52A and the outer cylindrical portion 83A. do. In other words, the pilot disc 52A slidably and tightly fits the seal member 72A into the outer cylindrical portion 83A of the housing 55A.

The plurality of discs 403 have the same outer diameter, which is smaller than the minimum inner diameter of the seal member 72A of the pilot disc 52A. The plurality of discs 403 have an outer diameter smaller than the outer diameter of the tip surface of the inner cylindrical portion 82A of the housing 55A on the side of the piston 18 and larger than the inner diameter of the large-diameter hole portion 93A.

The spring disk 404 includes a flat plate-like substrate portion 481 having an outer diameter larger than the outer diameter of the disk 403 and smaller than the minimum inner diameter of the seal member 72A of the pilot disk 52A, and a pressing plate extending from the substrate portion 481. and a portion 482 . The substrate portion 481 has an annular shape, and the pressing plate portion 482 extends from the outer peripheral edge portion of the substrate portion 481 while being inclined to one side in the axial direction and radially outward. A plurality of pressing plate portions 482 are intermittently formed at intervals in the circumferential direction of the substrate portion 481 and extend toward the partition disk 124A. The plurality of pressing plate portions 482 of the spring disk 404 contact the surface of the partition disk 124A on the pilot disk 52A side to urge the partition disk 124A toward the seat surface 431 to abut against the seat surface 431 .

The disc 405 has an outer diameter smaller than that of the base portion 481 of the spring disc 404 and larger than that of the tip surface of the inner cylindrical portion 82A of the housing 55A on the piston 18 side. The disk 405 is formed with a notch portion 485 extending radially outward from the inner peripheral edge portion that fits onto the mounting shaft portion 28A of the piston rod 21A. The passageway in cutout 485 is orifice 486 .

The orifice 486 is in constant communication with the pilot chamber 111A (pressure chamber) in the housing 55A that provides back pressure to the pilot disc 52A on the one hand, and the passage in the large diameter hole 93A of the housing 55A and the piston rod passage on the other hand. It always communicates with the part 46A. The orifice 486 is a throttle provided between the pilot chamber 111A and the piston rod passage portion 46A.

The pilot chamber 111A always communicates with the passage in the large diameter hole portion 93A of the housing 55A and the piston rod passage portion 46A of the piston rod 21A through the orifice 486. As shown in FIG. Through the portion 46A, it is in constant communication with the lower chamber 20 through the introduction orifice 212 of the disk 201 and the annular groove 40 and the passage hole 39 of the piston 18.

The plurality of discs 407 have the same outer diameter, which is slightly larger than the outer diameter of the tip surface of the valve seat 84A. A plurality of discs 407 constitute a hard valve 110A that can be seated on and removed from the valve seat 84A.

The disc 408 has an outer diameter smaller than the outer diameter of the disc 407 and the inner diameter of the tip end surface of the valve seat 84A, and is approximately the outer diameter of the tip end surface of the inner cylindrical portion 82A of the housing 55A opposite to the piston 18. have the same diameter. The disc 409 has an outer diameter larger than the outer diameter of the disc 408 and substantially the same diameter as the outer diameter of the tip surface of the valve seat 84A. The annular member 410 has a larger outer diameter than the hard valve 110A and a higher rigidity than the hard valve 110A. The disk 409 and the annular member 410 abut against the hard valve 110A when the hard valve 110A is deformed in the opening direction, thereby restricting the deformation of the hard valve 110A in the opening direction beyond a specified limit.

With the partition disk 124A blocking the passage in the through hole 437 and the hard valve 110A closing the passage in the through hole 438, the pilot chamber is defined between the pilot disk 52A, the housing 55A, the partition disk 124A and the hard valve 110A. A communication chamber 192A is formed between the bottom portion 81A of the housing 55A and the partition disk 124A and is always in communication with the lower chamber 20 via the passage in the through hole 437. As shown in FIG. Accordingly, these two pilot chambers 111A and communication chamber 192A are provided within the housing 55A and defined by the partition disc 124A.

The partition disc 124A has a state in which both the inner and outer peripheral sides thereof are in contact with the seat surface 431 of the disc contact portion 432 over the entire circumference, and both the inner and outer peripheral sides are in contact with the seat surface 431 and the stopper surface 433 over the entire circumference. and the state of surface contact with the stopper surface 433 over the entire circumference, block the flow of oil between the pilot chamber 111A and the communication chamber 192A. In addition, the partition disk 124A allows the oil to flow between the communication chamber 192A and the pilot chamber 111A when separated from the bottom portion 81A. The spring disk 404 will bias the partition disk 124A against the seat surface 431 .

Therefore, the spring disk 404, the partition disk 124A, the disk contact portion 432 and the recess 434 of the housing 55A restrict the flow of oil from the pilot chamber 111A side to the communication chamber 192A side, i.e., the lower chamber 20 side. , a check valve 195A that allows oil to flow from the communication chamber 192A side, ie, the lower chamber 20 side, to the pilot chamber 111A side.

The partition disk 124A, which is the valve body of the check valve 195A, is not axially clamped in its entirety and is not fixed to any part. Compartment disc 124A is spaced apart from abutting spring disc 404 and bottom 81A of housing 55A. The partition disk 124A is a floating type free valve whose entirety is axially movable. The partition disc 124A approaches and separates from the seat surface 431 with only the spring disc 404 urging the partition disc 124A except hydraulic pressure. Both the partition disk 124A and the spring disk 404 of the check valve 195A are made of metal only and do not use rubber seals. Both the partition disk 124A and the spring disk 404 are integrally molded from a single plate material by press working.

The biasing force of the spring disk 404 is set so that the partition disk 124A always blocks the flow of oil between the pilot chamber 111A and the communication chamber 192A regardless of the pressure states of the pilot chamber 111A and the communication chamber 192A. can be In other words, the partition disk 124A may block flow in both directions between the pilot chamber 111A and the communication chamber 192A. In other words, the partition disk 124A should block the flow of working fluid in at least one direction between the pilot chamber 111A and the communication chamber 192A.

Since the recess 434 is formed in the bottom 81A, the partition disk 124A can be deflected by the working fluid in the housing 55A, and communicates with the pilot chamber 111A when the pressure in the pilot chamber 111A becomes higher than the pressure in the communication chamber 192A. While blocking the communication with the chamber 192A, it bends so as to enter the concave portion 434 as described above, and deforms so as to increase the volume of the pilot chamber 111A and decrease the volume of the communication chamber 192A. In addition, when the pressure difference between the pressure in the pilot chamber 111A and the pressure in the communication chamber 192A becomes smaller from this state, the partition disk 124A cuts off the communication between the pilot chamber 111A and the communication chamber 192A, and allows the pressure to flow into the recess 434. The entrapment is reduced, the volume of the communication chamber 192A is increased, and the volume of the pilot chamber 111A is reduced. Further, when the pressure in the communication chamber 192A becomes higher than the pressure in the pilot chamber 111A by exceeding the biasing force of the spring disc 404, the partitioning disc 124A is separated from the seat surface 431 against the biasing force of the spring disc 404. The communication chamber 192A and the pilot chamber 111A are communicated with each other.

The disc 401 is seatable on the valve seat 47 of the piston 18 as described above. Disk 401 and pilot disk 52A constitute main valve 65A. The main valve 65A is provided in passages in the annular groove 38 and the passage hole 37 formed in the piston 18, and suppresses the flow of oil caused by the sliding of the piston 18 toward the extension side to generate a damping force. .

The main valve 65A and the valve seat 47 of the piston 18 constitute a first damping force generating mechanism 41A. When the disk 401 of the main valve 65</b>A is separated from the valve seat 47 and opened, the oil from the passages in the annular groove 38 and the passage hole 37 flows into the lower chamber 20 . The passage within the annular groove 38 and the passage hole 37 and between the main valve 65A and the valve seat 47 constitute a first extension passage 75 similar to that of the first embodiment. A first damping force generating mechanism 41A on the extension side, which includes a valve seat 47 and a main valve 65A, is provided in a first passage 75 provided in the piston 18, and the main valve 65A opens and closes the first passage 75. damping force is generated by suppressing the flow of the oil. The first passage 75 is also not formed with a fixed orifice that always communicates the upper chamber 19 and the lower chamber 20. Therefore, the first passage 75 is not a passage that constantly communicates the upper chamber 19 and the lower chamber 20. Absent.

The valve seat 84A surrounds the opening of the pilot chamber 111A on the side opposite to the piston 18 . The hard valve 110A is in contact with the valve seat 84A, and opens and closes the pilot chamber 111A by separating and contacting the valve seat 84A. By separating from the valve seat 84A, the hard valve 110A communicates the pilot chamber 111A with the lower chamber 20 and suppresses the flow of oil from the pilot chamber 111A to the lower chamber 20 to generate a damping force. A through hole 438 forming a pilot chamber 111A is provided in the bottom portion 81A of the housing 55A so as to face the hard valve 110A.

The pilot chamber 111</b>A applies internal pressure to the main valve 65</b>A in the direction of the piston 18 , that is, in the valve closing direction in which the disk 401 is seated on the valve seat 47 . The opening of the first damping force generating mechanism 41A including the main valve 65A is adjusted by the pressure in the pilot chamber 111A. In other words, the first damping force generating mechanism 41A includes a main valve 65A that opens and closes the first passage 75, a pilot chamber 111A that applies pressure to the main valve 65A in the valve closing direction, and the pilot chamber 111A and the main valve 65A. and a hard valve 110A that communicates the pilot chamber 111A with the lower chamber 20. As shown in FIG. In the first damping force generating mechanism 41A, the main valve 65A and the pilot chamber 111A are provided between the piston 18 and the outer cylindrical portion 83A of the housing 55A, and the partition disc 124A is provided on the bottom portion 81A of the housing 55A. there is

Also in the second embodiment, when the piston speed in the extension stroke is low, the first damping force generating mechanism 41A is closed and the second damping force generating mechanism 333 is opened, and the piston speed is higher than the low speed. In the speed region, both the first damping force generating mechanism 41A and the second damping force generating mechanism 333 are configured to open.

As in the first embodiment, the second damping force generating mechanism 333 shown in FIG. A passage between the outer annular portion 291 and the inner annular portion 292 of the valve 247, a case inner chamber 321, passages in the passage groove 272 and the large diameter hole portion 277 of the case member 248, and a piston rod passage of the piston rod 21A. The upper chamber 19 of the piston 18 includes the portion 46A, passages within the large diameter bore portion 45 of the piston 18, introduction orifices 212 of the disc 201, and passages within the annular groove 40 and the plurality of passage holes 39 of the piston 18. A second passage 332A is formed through which oil flows from the upper chamber 19 on the upstream side in the cylinder 2 to the lower chamber 20 on the downstream side by moving to the side.

As shown in FIG. 12, the second passage 332A is formed by a passage in the large diameter hole portion 93A of the housing 55A communicating with the piston rod passage portion 46A, an orifice 486 in the notch portion 485 of the disk 405, and the check valve 195A. It includes a communication chamber 192A and a partitioned pilot chamber 111A.

The second passage 332A serves as an elongation-side passage through which oil flows from the upper chamber 19 on the upstream side toward the lower chamber 20 on the downstream side during the movement of the piston 18 toward the upper chamber 19 side, that is, the extension stroke. When the hard valve 110A opens and leaves the valve seat 84A, the pilot chamber 111A of the second passage 332A communicates with the lower chamber 20. As shown in FIG.

The second passage 332A also includes a piston rod passage portion 46A within a passage cutout portion 30A formed by cutting out the piston rod 21A, in other words, a portion thereof is formed by cutting out the piston rod 21A. . In addition to forming the piston rod 21A by notching, the piston rod passage portion 46A may be formed by penetrating the inside of the piston rod 21A in the form of a hole.

As shown in FIG. 11, a second damping force generating mechanism 333 on the extension side including a sub-valve 331 and a second valve seat 281 is provided in the second passage 332A. The second damping force generating mechanism 333 has the piston rod 21A inserted radially inward, and is arranged on the upper chamber 19 side of one of the two upper and lower chambers 19 and 20 in the second passage 332A. there is The case inner chamber 321 and the pilot chamber 111A are always in communication with the piston rod passage portion 46A, and are always in communication with the lower chamber 20 via the introduction orifice 212, the annular groove 40 and the passage hole 39. The second passage 332A does not have a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to always communicate with each other. Absent.

The extension-side second passage 332A, which communicates between the upper chamber 19 and the lower chamber 20, is parallel to the extension-side first passage 75, which likewise communicates between the upper chamber 19 and the lower chamber 20. A first damping force generating mechanism 41A is provided in one of the first passage 75 and the second passage 332A, and a second damping force generating mechanism 333 is provided in the other second passage 332A. there is Therefore, both the first damping force generating mechanism 41A and the second damping force generating mechanism 333 on the extension side are arranged in parallel.

As in the first embodiment, the second damping force generating mechanism 343 is opened during the compression stroke, and the passages in the plurality of passage holes 39 of the piston 18 and the annular groove 40 and the introduction orifice 212 of the disk 201 are closed. , the passage in the large diameter hole portion 45 of the piston 18, the piston rod passage portion 46A of the piston rod 21A, the passages in the large diameter hole portion 277 and the passage groove 272 of the case member 248, and the case inner chamber 321. , the passage between the sub-valve 341 and the first valve seat 271 appearing when the valve is opened, and the movement of the piston 18 toward the lower chamber 20 side, that is, the upper chamber on the downstream side from the lower chamber 20 on the upstream side in the compression stroke. A second passage 342A on the contraction side through which the oil flows out toward 19 is formed.

As shown in FIG. 12, the second passage 342A includes a passage in the large-diameter hole portion 93A of the housing 55A communicating with the piston rod passage portion 46A, an orifice 486 in the notch portion 485 of the disk 405, and the pilot chamber 111A. , the passage of the check valve 195A appearing when the valve is open, the communication chamber 192A, and the passage in the through hole 437. The partition disk 124A that constitutes the check valve 195A is configured to block the flow of oil from the pilot chamber 111A of the second passage 332A, which is one of the second passages 332A and 342A, to the communication chamber 192A. It is configured to allow oil to flow from a communication chamber 192A of a certain second passage 342A to the pilot chamber 111A. The second passage 342A includes a piston rod passage portion 46A within the passage cutout 30A of the piston rod 21A.

A compression-side second damping force generating mechanism 343 including a sub-valve 341 and an annular first valve seat 271 formed on the outer cylindrical portion 262 of the case member 248 is provided in the second passage 342A. The second damping force generating mechanism 343 has the piston rod 21A inserted radially inward, and is arranged on one upper chamber 19 side of the two upper and lower chambers 19 and 20 in the second passage 342A. . The second passage 342A does not have a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to always communicate with each other.

The second damping force generating mechanism 333 is provided at the end of the second passage 332A on the upper chamber 19 side, and the second damping force generating mechanism 343 is located at the end of the second passage 342A on the upper chamber 19 side. is provided in

A housing 55A provided in a common portion of the second passages 332A and 342A, and a common portion of the second passages 332A and 342A provided in the housing 55A are arranged on the upper chamber 19 side on one side and the lower chamber 20 side on the other side. Compartment disc 124A, which defines pilot chamber 111A within housing 55A, constitutes frequency sensitive mechanism 121A. The frequency sensitive mechanism 121A is arranged in the lower chamber 20. As shown in FIG. The frequency sensitive mechanism 121A performs frequency sensitive operation only in the extension stroke, and the frequency sensitive function is canceled in the contraction stroke.

As shown in FIG. 11, the extremely low speed valve mechanism 231, the main valve 221, the piston 18, the main valve 65A, the frequency sensitive mechanism 121A, the hard valve 110A, etc. are assembled to the piston rod 21A, and are attached to the male screw 31 of the mounting shaft portion 28A. A nut 361 is screwed. As a result, the nut 361 and the shaft stepped portion 29 of the piston rod 21A, except for the partition disk 124A of the frequency sensitive mechanism 121A, are connected to the extremely low speed valve mechanism 231, the main valve 221, the piston 18, the main valve 65A, the frequency sensitive mechanism 121A and the frequency sensitive mechanism 121A. At least the inner peripheral side of the hard valve 110A or the like is axially clamped.

Then, the very low speed valve mechanism 231, the main valve 221 and the piston 18 are in the same mounting state as in the first embodiment. In this mounted state, the inner peripheral side of the main valve 65A is clamped between the disk 403 and the portion radially inside the annular groove 38 of the piston 18 via the disk 400, and the disk 401 is engaged with the valve of the piston 18. It abuts on the seat 47 over the entire circumference.

Also, in this attached state, the inner peripheral sides of the substrate portion 481 of the spring disc 404 and the disc 405 are clamped between the disc 403 and the inner cylindrical portion 82A of the housing 55A. Also, in this attached state, the pressing plate portion 482 of the spring disk 404 abuts against the partition disk 124A, thereby bringing the partition disk 124A into contact with the seat surface 431 of the housing 55A over the entire circumference. In this mounted state, the hard valve 110A is clamped at its inner periphery by the inner cylindrical portion 82A of the housing 55A and the disc 408, and is in contact with the valve seat 84A of the housing 55A over its entire periphery.

In the shock absorber 1A as well, the upper chamber 19 and the lower chamber 20 are connected to the first damping force generating mechanisms 41A and 42 and the second damping force generating mechanisms 333, 333, 333, 333, 333, 333, 333, 333, 333, 333. 343 only. Therefore, the shock absorber 1A is not provided with a fixed orifice that constantly communicates between the upper chamber 19 and the lower chamber 20 at least on the oil passage that passes through the piston 18 in the axial direction.

The second passage 342A on the contraction side that can communicate between the upper chamber 19 and the lower chamber 20 includes a first passage 222 that is a passage on the contraction side that similarly communicates between the upper chamber 19 and the lower chamber 20, and the lower chamber 20 side. The first passage 222 and the second passage 342A are arranged in parallel except passages in the plurality of passage holes 39 and the annular groove 40, and the first passage 222 and the first damping force generating mechanism 42 However, a second damping force generating mechanism 343 is provided in each of the second passages 342A. Therefore, both the first damping force generating mechanism 42 and the second damping force generating mechanism 343 on the compression side are arranged in parallel.

In the compression stroke, the pressure in the lower chamber 20 increases and the pressure in the upper chamber 19 decreases as the piston 18 moves to the lower chamber 20 side. Since neither of the generating mechanisms 333, 343 has a fixed orifice that communicates the lower chamber 20 with the upper chamber 19, oil does not flow until the second damping force generating mechanism 343 is opened. Therefore, the damping force rises sharply. In a region where the piston speed is higher than the first predetermined value at which the second damping force generating mechanism 343 opens, and is lower than the second predetermined value, which is higher than the first predetermined value and lower than the second predetermined value, the second While the first damping force generating mechanism 42 is closed, the second damping force generating mechanism 343 is opened and oil flows from the lower chamber 20 to the upper chamber 19 through the second passage 342A.

That is, the sub-valve 341 is separated from the first valve seat 271, and the lower chamber 20 and the upper chamber 19 are communicated with each other through the second passage 342A on the contraction side. Therefore, the oil in the lower chamber 20 flows through the passages in the plurality of passage holes 39 and the annular groove 40 of the piston 18 and the introduction orifice 212 to the piston in the passage cutout 30A of the piston rod 21A. On the other hand, from the passage in the through-hole 437 of the frequency sensitive mechanism 121A and the communication chamber 192A, the check valve 195A is opened, the air flows to the pilot chamber 111A, and through the orifice 486 to the piston rod passage 46A. flow. From the piston rod passage portion 46A, passages in the large diameter hole portion 277 of the case member 248 and in the passage groove 272, the case inner chamber 321, the sub-valve 341 of the second damping force generating mechanism 343 and the first valve seat 271. and into the upper chamber 19 via the passageway between . As a result, a damping force with valve characteristics (a characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in an extremely low speed range in which the piston speed is lower than the second predetermined value. At this time, the pressure loss caused by the introduction orifice 212 and the orifice 486 provided in series with the second damping force generating mechanism 343, which occurs when the piston speed increases, determines the slope of the damping force in the extremely low speed region.

In the compression stroke, the first damping force generating mechanism 42 opens while the second damping force generating mechanism 343 remains open in the normal speed region where the piston speed is equal to or higher than the second predetermined value. In other words, the sub-valve 341 is separated from the first valve seat 271 in the same manner as described above, and oil flows from the lower chamber 20 to the upper chamber 19 through the second passage 342A on the contraction side. Leaving the seat 48, oil flows from the lower chamber 20 to the upper chamber 19 also in the first passage 222 on the contraction side. Therefore, in addition to the second passage 342A, the oil in the lower chamber 20 passes through passages in the plurality of passage holes 39 and the annular groove 40 that constitute the first passage 222, and passages between the main valve 221 and the valve seat 48. and flows through. As a result, even in the normal speed region where the piston speed is equal to or higher than the second predetermined value, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) can be obtained. The increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region is lower than the increase rate of the compression damping force with respect to the increase in piston speed in the extremely low speed region. In other words, the slope of the increase rate of the compression damping force with respect to the increase in piston speed in the normal speed region can be flatter than in the extremely low speed region.

In the extension stroke, the pressure in the upper chamber 19 increases and the pressure in the lower chamber 20 decreases as the piston 18 moves toward the upper chamber 19. Since neither of the generating mechanisms 333, 343 has a fixed orifice that communicates the upper chamber 19 with the lower chamber 20, oil does not flow until the second damping force generating mechanism 333 is opened. Therefore, the damping force rises sharply in the extension stroke when the piston speed is less than the third predetermined value. In addition, in a region where the piston speed is higher than the third predetermined value at which the second damping force generating mechanism 333 opens, and is lower than the fourth predetermined value, which is higher than the third predetermined value, it is extremely low speed region. , the second damping force generating mechanism 333 opens while the first damping force generating mechanism 41A is closed.

In other words, the sub-valve 331 is separated from the second valve seat 281, and the upper chamber 19 and the lower chamber 20 are communicated with each other through the extension-side second passage 332A. Therefore, the oil in the upper chamber 19 flows between the passage between the open sub-valve 331 and the second valve seat 281, which constitutes the second passage 332A, and between the outer annular portion 291 and the inner annular portion 292 of the disk valve 247. , the case inner chamber 321, the passages in the passage groove 272 and the large diameter hole portion 277 of the case member 248, the piston rod passage portion 46A of the piston rod 21A, and the large diameter hole portion 45 of the piston 18 It flows into the lower chamber 20 via the passageway, the introduction orifice 212 and the passageway within the annular groove 40 of the piston 18 and within the plurality of passage holes 39 . As a result, even in an extremely low speed region in which the piston speed is lower than the fourth predetermined value, a damping force with a valve characteristic (a characteristic in which the damping force is substantially proportional to the piston speed) can be obtained. At this time, the pressure loss caused by the introduction orifice 212 provided in series with the second damping force generating mechanism 333, which occurs when the piston speed increases, determines the slope of the damping force in the extremely low speed region.

Further, in the extension stroke, in the normal speed range where the piston speed is equal to or higher than the fourth predetermined value, the first damping force generating mechanism 41A opens while the second damping force generating mechanism 333 remains open. In other words, the sub-valve 331 is separated from the second valve seat 281, and oil flows from the upper chamber 19 to the lower chamber 20 through the extension-side second passage 332A, and the main valve 65A is separated from the valve seat 47. While sitting down, oil is allowed to flow from the upper chamber 19 to the lower chamber 20 through the first passage 75 on the extension side. Therefore, in addition to the second passage 332A, the oil in the upper chamber 19 passes through passages within the plurality of passage holes 37 of the first passage 75 and the annular groove 38, and passages between the main valve 65A and the valve seat 47. flows into the lower chamber 20 via the .

At this time, the valve opening pressure of the main valve 65A changes according to the pressure of the pilot chamber 111A forming part of the second passage 332A. That is, when the input to the piston rod 21A has a low frequency and a large stroke, oil flows into the pilot chamber 111A forming part of the second passage 332A, and the volume of the pilot chamber 111A increases. , the partition disk 124A is largely deformed, but the partition disk 124A is then brought into contact with the stopper surface 433 of the concave portion 434 to restrict the deformation. Therefore, when the hydraulic fluid further flows into the pilot chamber 111A, the pressure in the pilot chamber 111A increases and the opening pressure of the main valve 65A also increases, resulting in a hard damping force characteristic.

On the other hand, when the input to the piston rod 21A has a high frequency and a small stroke, oil flows into the pilot chamber 111A forming part of the second passage 332A, and the volume of the pilot chamber 111A increases. Although the partition disk 124A is deformed, the amount of deformation is small. Therefore, the partition disk 124A is not deformed to the point where the deformation is restricted by coming into contact with the stopper surface 433 of the concave portion 434, and is deformed by the amount of oil flowing into the pilot chamber 111A. Therefore, since the pressure in the pilot chamber 111A does not rise, the opening pressure of the main valve 65A is low, resulting in a soft damping force characteristic.

The shock absorber 1A of the second embodiment described above can achieve the same effects as the shock absorber 1 of the first embodiment. In addition, the main valve 65A of the extension-side first damping force generating mechanism 41A is provided between the piston 18 and the outer cylindrical portion 83A of the housing 55A, and the partition disc 124A of the frequency sensitive mechanism 121A Since it is provided on the bottom portion 81A of the housing 55A, it is possible to reduce the number of parts and shorten the shaft length.

In other words, since the pilot chamber 111A for applying pressure in the valve closing direction to the main valve 65A of the first damping force generating mechanism 41A on the extension side is formed by the housing 55A and the partition disc 124A of the frequency sensitive mechanism 121A, the number of parts is reduced. reduction and shortening of the axial length can be achieved.

A first aspect of the above-described embodiments includes a cylinder in which a working fluid is enclosed, a piston movably provided in the cylinder and partitioning the inside of the cylinder into one side chamber and the other side chamber, and the piston a piston rod connected to the cylinder and extending to the outside of the cylinder; a first damping force generating mechanism provided in the first passage provided in the piston to generate a damping force; and a second damping force generating mechanism provided in the second passage parallel to the first passage to generate a damping force. 2. A damping force generating mechanism, a housing provided in the second passage, and the second passage provided in the housing defining the first chamber side and the second chamber side, and forming a pressure chamber in the housing. and a frequency sensitive mechanism comprising a dividing member, wherein in a region where the piston speed is low, the first damping force generating mechanism is closed and the second damping force generating mechanism is opened, and the piston speed is is higher than low speed, both the first damping force generating mechanism and the second damping force generating mechanism are configured to open, the second damping force generating mechanism is arranged in the one side chamber, and the frequency A sensitive mechanism is disposed in the other side chamber. As a result, the damping force of the valve characteristic can be obtained from the region where the piston speed is low, and the damping force can be made variable depending on the frequency.

According to a second aspect, in the first aspect, the second passage has a piston rod passage portion formed by notching or penetrating the piston rod.

A third aspect is the first or second aspect, wherein the housing comprises a first tubular portion and a first bottom portion, and the second damping force generating mechanism comprises a second tubular portion and a second bottom portion. An annular first valve seat formed in the second cylindrical portion of a cylindrical case member with a bottom, and a detachable contact portion on the outer peripheral side of the first valve seat of the case member is detachably disposed. an annular disc valve; and a second valve seat provided on the opposite side of the disc valve in the axial direction from the first valve seat, and supporting the disc valve radially inward from the contact/separation portion of the disc valve so as to be separable and contactable. and wherein the partition member is a deflectably disposed disc, the disc configured to block the flow of working fluid to at least one of the second passages.

In a fourth aspect based on the third aspect, the disc valve comprises an outer annular portion that is detachably arranged on the first valve seat and the second valve seat, and an inner annular portion that is fitted to the piston rod. and a support portion connecting the outer annular portion and the inner annular portion.

A fifth aspect is the third or fourth aspect, wherein the first damping force generating mechanism is provided between the piston and the first cylindrical portion of the housing, and the disc is located on the first bottom portion. provided in

In a sixth aspect, in any one of the first to fifth aspects, the first damping force generating mechanism includes a valve member that opens and closes the first passage, and applies pressure to the valve member in a valve closing direction. and a pilot chamber, wherein the housing and the partition member define the pilot chamber.

1, 1A shock absorber 2 cylinder 18 piston 19 upper chamber (one side chamber)
20 lower chamber (other side chamber)
21, 21A Piston rod 41, 41A, 42 First damping force generating mechanism 46, 46A Piston rod passage 55A, 122 Housing 65A Main valve (valve member)
75, 222 first passage 81A bottom (first bottom)
83A outer cylindrical portion (first cylindrical portion)
111A Pilot chamber (pressure chamber)
121, 121A frequency sensitive mechanism 124, 124A partition disk (partition member, disk)
141 bottom (first bottom)
142 cylinder part (first cylinder part)
191 pressure chamber 247 disc valve 248 case member 261 bottom (second bottom)
262 outer cylindrical portion (second cylindrical portion)
271 First valve seat 281 Second valve seat 291 Outer annular portion 292 Inner annular portion 293 Supporting portion 301 Outer peripheral side separation portion (separation contact portion)
332, 332A, 342, 342A Second passage 333, 343 Second damping force generating mechanism

Claims (5)

a cylinder in which the working fluid is sealed;
a piston movably provided in the cylinder and partitioning the inside of the cylinder into one side chamber and the other side chamber;
a piston rod connected to the piston and extending outside the cylinder;
a first passage and a second passage through which the working fluid moves from an upstream chamber to a downstream chamber in the cylinder by movement of the piston;
a first damping force generating mechanism provided in the first passage provided in the piston to generate a damping force;
a second damping force generating mechanism provided in the second passage parallel to the first passage to generate a damping force;
A frequency comprising a housing provided in the second passage and a dividing member provided in the housing to define the second passage on the one side chamber side and the other side chamber side and form a pressure chamber in the housing. a sensitive mechanism;
has
In a region where the piston speed is low, the first damping force generation mechanism is closed and the second damping force generation mechanism is opened, and in a speed region where the piston speed is higher than the low speed, the first damping force is generated. The mechanism and the second damping force generating mechanism are both configured to open,
The second damping force generating mechanism is arranged in the one side chamber, the frequency sensitive mechanism is arranged in the other side chamber ,
The first damping force generating mechanism includes a valve member that opens and closes the first passage, and a pilot chamber that applies pressure to the valve member in a valve closing direction. A buffer characterized by: 2. The shock absorber according to claim 1, wherein the second passage has a piston rod passage portion formed by notching or penetrating the piston rod. the housing comprises a first cylindrical portion and a first bottom portion;
The second damping force generating mechanism includes an annular first valve seat formed in the second tubular portion of a bottomed tubular case member having a second tubular portion and a second bottom; An annular disk valve having a first valve seat on which an outer peripheral side separation/contact portion can be separated and contacted, and the first valve seat of the disk valve are provided on the opposite side in the axial direction of the disk valve. a second valve seat that detachably supports the radial inner side of the contact portion,
3. The dividing member is a disc arranged in a deflectable state, the disc being configured to block the flow of working fluid to at least one of the second passages. 2. The buffer according to 2. The disk valve includes an outer annular portion that is detachably arranged between the first valve seat and the second valve seat, an inner annular portion that fits into the piston rod, and the outer annular portion and the inner annular portion. 4. The shock absorber according to claim 3, further comprising a support portion connecting the . 5. The first damping force generating mechanism according to claim 3, wherein the first damping force generating mechanism is provided between the piston and the first cylindrical portion of the housing, and the disc is provided on the first bottom portion. buffer.

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