WO2018062151A1

WO2018062151A1 - Shock absorber

Info

Publication number: WO2018062151A1
Application number: PCT/JP2017/034690
Authority: WO
Inventors: 幹郎山下
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2016-09-27
Filing date: 2017-09-26
Publication date: 2018-04-05
Also published as: JP2019206971A

Abstract

This shock absorber has: first and second passages having working fluid flowing thereto from either a first chamber or a second chamber, as a result of movement of a piston; and a first valve that generates damping force and is provided in the first passage. The second passage has provided therein, in series: a second valve that opens at a smaller pressure than the first valve and generates damping force; and a frequency-sensitive section having a third valve that, when working fluid flows from the first chamber to the second chamber, can move inside a housing while defining the inside of the housing into an upstream side and a downstream side, and can open when working fluid flows from the second chamber to the first chamber.

Description

Shock absorber

The present invention relates to a shock absorber.
This application claims priority on September 27, 2016 based on Japanese Patent Application No. 2016-188038 filed in Japan, the contents of which are incorporated herein by reference.

Conventionally, there is a shock absorber provided with a damping force variable mechanism that varies the damping force according to the frequency (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-202800

There is a demand for a shock absorber to vary the damping force greatly according to the frequency from the region where the piston speed is slow.

Therefore, an object of the present invention is to provide a shock absorber capable of greatly changing the damping force according to the frequency from the region where the piston speed is low.

According to the first aspect of the present invention, the shock absorber is slidably fitted into the cylinder in which the working fluid is sealed, and the cylinder has two chambers, a first chamber and a second chamber. And a piston rod connected to the piston and extending to the outside of the cylinder, and a first passage and a second passage through which the working fluid flows from one of the first chamber and the second chamber by the movement of the piston And a first valve body that is provided in the first passage and generates a damping force, and the second passage is opened with a pressure smaller than that of the first valve body to generate the damping force. And when the working fluid flows from the first chamber to the second chamber, the second valve body is movable in the housing while defining the inside of the housing into an upstream side and a downstream side, and the second chamber Can be opened when working fluid flows from the to the first chamber A frequency response unit having a third valve element such, but are provided in series.

According to the second aspect of the present invention, in the shock absorber according to the first aspect, the first chamber is a rod-side chamber, the second chamber is a bottom-side chamber, and the first chamber is in the extension stroke. A three-valve body moves in the housing while defining the inside of the housing on the upstream side and the downstream side, thereby changing the damping force according to the frequency, and in the contraction stroke, the third valve body May be openable.

According to the third aspect of the present invention, in the shock absorber according to the second aspect, the second valve side of the third valve body is arranged in the housing at the upstream side during the contraction stroke. A frequency sensitive portion having a fourth valve body that is movable in the housing while being defined on the downstream side and that can be opened during the extension stroke may be provided.

According to the fourth aspect of the present invention, in the shock absorber according to any one of the first to third aspects, the frequency sensitive part includes a cylindrical case member and a shaft part disposed in the case member. And an annular elastic seal that is disposed in the case member so as to penetrate the shaft portion, the inner peripheral side or the outer peripheral side is supported, and the non-support side seals between the case member or the shaft portion The member may be provided with a ring-shaped third valve body that can be bent, and two chambers in the case member that are defined by the third valve body.

According to the present invention, in the shock absorber, the damping force can be greatly varied according to the frequency from the region where the piston speed is low.

It is sectional drawing which shows the shock absorber which concerns on 1st Embodiment of this invention. It is a fragmentary sectional view of the piston periphery which shows the buffer which concerns on 1st Embodiment of this invention. It is a fragmentary sectional view around the frequency sensitive part which shows the buffer concerning a 1st embodiment of the present invention. 1 is a hydraulic circuit diagram showing a shock absorber according to a first embodiment of the present invention. It is a characteristic line figure which shows notionally the relation of damping force with respect to piston speed of a buffer concerning a 1st embodiment of the present invention. It is a Lissajous waveform diagram which shows the relationship between the stroke and damping force when the piston speed of the shock absorber according to the first embodiment of the present invention is 0.03 m / s. It is a frequency characteristic diagram which shows the relationship of the damping force with respect to the frequency when the piston speed of the buffer which concerns on 1st Embodiment of this invention is 0.03 m / s. It is a Lissajous waveform diagram which shows the relationship between the stroke and damping force when the piston speed of the shock absorber according to the first embodiment of the present invention is 0.3 m / s. It is a frequency characteristic diagram which shows the relationship of the damping force with respect to the frequency when the piston speed of the buffer which concerns on 1st Embodiment of this invention is 0.3 m / s. It is a fragmentary sectional view around a frequency sensitive part showing a buffer concerning a 2nd embodiment of the present invention. It is a hydraulic circuit diagram which shows the buffer which concerns on 2nd Embodiment of this invention. It is a characteristic diagram which shows notionally the relationship of the damping force with respect to the piston speed of the buffer which concerns on 2nd Embodiment of this invention. It is a fragmentary sectional view around the frequency sensitive part which shows the buffer concerning a 3rd embodiment of the present invention.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. In the following description, for convenience of explanation, the upper side in the drawing is described as “upper”, and the lower side in the drawing is described as “lower”.

As shown in FIG. 1, the shock absorber 11 according to the first embodiment is a so-called single cylinder type hydraulic shock absorber, and has a cylinder 12 in which an oil liquid as a working fluid is enclosed. The cylinder 12 is a bottomed cylindrical integral molded product, and a cover 15 is attached so as to cover the upper opening side of the bottomed cylindrical shape. A plate-like body 16 is attached to the cover 15 on the side opposite to the cylinder 12. The cylinder 12 includes a cylindrical body portion 21 and a bottom portion 22 that closes a lower portion of the body portion 21, and the body portion 21 is open on the opposite side of the bottom portion 22 in the axial direction.

The cover 15 has a cylindrical portion 25 and an inner flange portion 26. The inner flange portion 26 extends radially inward from the upper end side of the tubular portion 25. The cover 15 is placed on the opening side of the body portion 21 so that the upper end opening of the body portion 21 is covered with the inner flange portion 26 and the outer peripheral surface of the body portion 21 is covered with the tubular portion 25. In this state, the cover 15 and a part of the cylindrical portion 25 are crimped inward in the radial direction, and the cover 15 is fixed to the trunk portion 21. The plate-like body 16 is fixed on the opposite side to the cylindrical portion 25 of the inner flange portion 26 in the axial direction.

The piston 30 is slidably fitted in the body portion 21 of the cylinder 12. The piston 30 divides the inside of the cylinder 12 into two chambers, an upper chamber 31 (first chamber, rod side chamber) and a lower chamber 32 (second chamber, bottom side chamber). A partition piston 35 is provided in the body portion 21 of the cylinder 12 on the bottom 22 side of the piston 30. The partition piston 35 is partitioned from the lower chamber 32 between the bottom portion 22 and a chamber 36 is formed. An oil liquid as a working fluid is sealed in the upper chamber 31 and the lower chamber 32 in the cylinder 12, and a high-pressure gas is sealed in the chamber 36 in the cylinder 12.

The other end side of the piston rod 41 whose one end extends to the outside of the cylinder 12 is inserted into the cylinder 12. The piston 30 is connected to the other end side of the piston rod 41 disposed in the cylinder 12. The piston 30 and the piston rod 41 move together. In the extension stroke in which the piston rod 41 increases the amount of protrusion from the cylinder 12, the piston 30 moves to the upper chamber 31 side. In the contraction stroke in which the piston rod 41 reduces the amount of protrusion from the cylinder 12, the piston 30 moves to the lower chamber 32 side.
The upper chamber 31 is a rod side chamber in which the piston rod 41 is disposed, and the lower chamber 32 is a bottom side chamber on the bottom 22 side of the cylinder 12.

The rod guide 42 is fitted to the upper end opening side of the cylinder 12. A seal member 43 is fitted on the upper side, which is the outside of the cylinder 12, with respect to the rod guide 42. A part of the upper end portion of the cylinder 12 is caulked inward in the radial direction to lock the seal member 43. A friction member 44 is provided between the rod guide 42 and the seal member 43. The rod guide 42, the seal member 43, and the friction member 44 all have an annular shape. The piston rod 41 is slidably inserted inside the rod guide 42, the friction member 44, and the seal member 43, and extends to the outside of the cylinder 12.

Here, the rod guide 42 supports the piston rod 41 so as to be movable in the axial direction while restricting the radial movement of the piston rod 41, and guides the movement of the piston rod 41. The outer peripheral portion of the seal member 43 is in close contact with the cylinder 12, and the inner peripheral portion of the seal member 23 is in sliding contact with the outer peripheral portion of the piston rod 41 moving in the axial direction, so that the oil in the cylinder 12 leaks to the outside. To prevent. The inner peripheral portion of the friction member 44 is in sliding contact with the outer peripheral portion of the piston rod 41, and the friction member 44 causes the piston rod 41 to generate a frictional resistance. The friction member 44 is not a member intended for sealing.

The piston rod 41 includes a rod body 51, a tip rod 55, an annular member 57, and a nut member 58. The rod body 51 is inserted through the rod guide 42, the seal member 43, and the friction member 44 and extends from the cylinder 12 to the outside. The tip rod 55 has a female screw 54 at the end inside the cylinder 12 in the rod main body 51, and the male screw 52 is screwed into the female screw 54 and extends from the rod main body 51 to the bottom 22 side. The annular member 57 is in contact with the tip rod 55 by inserting the rod body 51 inward. The nut member 58 is screwed to the male screw 52 so as to sandwich the annular member 57 with the tip rod 55.

A locking member 61 is fixed to the outer periphery of the rod body 51 on the tip rod 55 side. On the outer peripheral side of the rod body 51,

annular spring receivers

62 and 63 are provided between the locking member 61 and the rod guide 42. The

spring receivers

62 and 63 are configured to be slidable along the rod body 51 by inserting the rod body 51 inward. A rebound spring 64 made of a coil spring is interposed between the

spring receivers

62 and 63 so that the rod body 51 is inserted inside the rebound spring 64. A shock absorber 65 made of an annular elastic material is provided on the opposite side of the spring receiver 63 on the rod guide 42 side from the rebound spring 64. The buffer body 65 is also slidable along the rod body 51 by inserting the rod body 51 inward.

The tip rod 55 has a base shaft portion 71 in which a female screw 54 is formed, and an attachment shaft portion 72 having a smaller diameter. A piston 30 or the like is attached to the attachment shaft portion 72. An end portion of the base shaft portion 71 on the mounting shaft portion 72 side is formed with a shaft step portion 73 that extends from the mounting shaft portion 72 along the direction orthogonal to the axis. A passage groove 75 extending in the axial direction is formed at an intermediate position in the axial direction on the outer peripheral portion of the attachment shaft portion 72. In the mounting shaft portion 72, a male screw 76 is formed at the tip position on the opposite side of the axial base shaft portion 71. The passage groove 75 is formed so that the cross-sectional shape on the surface orthogonal to the central axis of the piston rod 41 is any one of a rectangle, a square, and a D-shape.

In the shock absorber 11, for example, a protruding portion of the piston rod 41 from the cylinder 12 is arranged at the top and supported by the vehicle body, and the bottom 22 side of the cylinder 12 is arranged at the bottom and connected to the wheel side. On the contrary, the cylinder 12 side may be supported by the vehicle body, and the piston rod 41 may be connected to the wheel side. When the wheels vibrate as the vehicle travels, the positions of the cylinder 12 and the piston rod 41 change relatively with the vibration. The change is a flow formed in at least one of the piston 30 and the piston rod 41. Suppressed by the fluid resistance of the path. As will be described in detail below, the flow path formed in at least one of the piston 30 and the piston rod 41 is formed so that the fluid resistance of the flow path varies depending on the vibration speed and amplitude, thereby suppressing vibration. By doing so, the ride comfort of the vehicle body is improved. Between the cylinder 12 and the piston rod 41, in addition to vibrations generated by the wheels, inertial force and centrifugal force generated in the vehicle body as the vehicle travels also act. For example, a centrifugal force is generated in the vehicle body when the traveling direction is changed by a steering operation, and a force based on the centrifugal force acts between the cylinder 12 and the piston rod 41. As will be described below, the shock absorber 11 has good characteristics against vibration based on the force generated in the vehicle body as the vehicle travels, and high stability in vehicle travel can be obtained.

As shown in FIG. 2, the piston 30 has a piston main body 83. The piston main body 83 has two

piston components

80 and 81 and a sliding member 82. The piston

structural bodies

80 and 81 are two metal members that are connected to each other and in which the mounting shaft portion 72 of the tip rod 55 is fitted to the inner peripheral portion. The sliding member 82 is an annular synthetic resin member that is integrally attached to the outer peripheral surfaces of the piston

structural bodies

80 and 81 and slides in the cylinder 12. In the piston 30, the piston body 83 divides the inside of the cylinder 12 into two chambers, an upper chamber 31 and a lower chamber 32.

The piston main body 83 includes a plurality of first passage holes 88 (only one place is shown because of the cross section in FIG. 2) and a plurality of second passage holes 89 (only one place is shown because of the cross section shown in FIG. 2). And are provided. The plurality of first passage holes 88 are formed so as to be able to communicate with the upper chamber 31 and the lower chamber 32 by penetrating in the axial direction. The plurality of second passage holes 89 are formed so as to communicate with the upper chamber 31 and the lower chamber 32 by penetrating in the axial direction. In other words, the passage of the plurality of first passage holes 88 and the passage of the plurality of second passage holes 89 cause the hydraulic fluid as the working fluid to flow between the upper chamber 31 and the lower chamber 32 by the movement of the piston 30. The upper chamber 31 and the lower chamber 32 communicate with each other. The plurality of first passage holes 88 are formed at an equal pitch in the circumferential direction with one second passage hole 89 interposed between the first passage holes 88. The first axial side (upper side in FIG. 2) of the piston body 83 opens radially outward, and the second axial side (lower side in FIG. 2) opens radially inward.

A damping force generation mechanism 90 that generates a damping force is provided for each first passage hole 88. The damping force generation mechanism 90 includes a valve body 91 (first valve body) that is disposed on the lower chamber 32 side, which is one end side in the axial direction of the piston body 83, and is attached to the attachment shaft portion 72 of the piston rod 41. ing. The passage inside the first passage hole 88 is an extension through which the oil liquid passes during the movement of the piston 30 toward the upper chamber 31, that is, the extension stroke in which the piston rod 41 and the piston 30 move to the extension side (upper side in FIG. 2). Side passage 108 (first passage) is formed. The damping force generation mechanism 90 provided for each first passage hole 88 constitutes an extension-side damping force generation mechanism that generates a damping force by suppressing the flow of oil in the extension-side passage 108. . The valve body 91 is provided in the passage 108 and generates a damping force.

Further, the second passage hole 89 constituting the remaining half of the plurality of passage holes 88 and 89 has one first passage hole 88 sandwiched between the second passage holes 89 in the circumferential direction, etc. The other side of the piston body 83 in the axial direction (lower side in FIG. 2) opens radially outward, and one side in the axial direction (upper side in FIG. 2) opens radially inward.

Each second passage hole 89 is provided with a damping force generating mechanism 92 that generates a damping force. The damping force generation mechanism 92 includes a valve body 93 that is disposed on the upper chamber 31 side that is the other end side in the axial direction of the piston main body 83 and is attached to the piston rod 41. The passage inside the second passage hole 89 moves in the contraction stroke in which the piston 30 moves toward the lower chamber 32, that is, the piston rod 41 and the piston 30 move toward the contraction side (the lower side in FIG. 2). A contraction-side passage 119 is formed. The damping force generation mechanism 92 provided in each second passage hole 89 constitutes a contraction-side damping force generation mechanism that generates a damping force by suppressing the flow of oil in the passage in the contraction-side passage 119. Yes.

The piston body 83 has an annular shape, and the mounting shaft portion 72 of the tip rod 55 is fitted to the inner peripheral portion of the piston body 83. An annular valve seat 97 is formed on the end of the piston body 83 on the lower chamber 32 side in the axial direction and radially outside the opening on the lower chamber 32 side of the first passage hole 88. The valve seat portion 97 and the valve body 91 constitute a damping force generation mechanism 90. An annular valve seat 99 is formed on the end of the piston body 83 on the upper chamber 31 side in the axial direction, on the radially outer side than the opening on the upper chamber 31 side of the second passage hole 89. The valve seat 99 and the valve body 93 constitute a damping force generation mechanism 92.

In the piston main body 83, the outer peripheral side of the valve seat portion 97 is formed in a step shape whose axial height is lower than that of the valve seat portion 97, and this step-shaped portion is below the second passage hole 89 on the contraction side. An opening on the chamber 32 side is arranged. Similarly, in the piston main body 83, the outer peripheral side of the valve seat part 99 is formed in a stepped shape having a lower height in the axial direction than the valve seat part 99, and the first side on the extending side is formed in this stepped part. An opening on the upper chamber 31 side of the passage hole 88 is disposed.

The valve body 91 is configured by stacking a plurality of perforated disk-shaped disks 101. In the valve body 91, the outer diameter of the disk 101 closest to the piston body 83 is the largest, and the outer diameter of the disk 101 on the opposite side to the piston body 83 is smaller than the disk 101. Further, the outer diameter of the disk 101 at the intermediate portion in the stacking direction is the intermediate diameter of each disk at both ends in the stacking direction. A mounting shaft 72 is fitted to the inner periphery of the disc 101. The valve body 91 is in contact with the valve seat portion 97 of the piston body 83 by the disk 101 closest to the piston body 83 to open and close the passage in the first passage hole 88.

Between the valve body 91 and the piston main body 83, a plurality of perforated disc-shaped disks 103 are provided. Each of the plurality of disks 103 has an outer diameter smaller than the inner diameter of the valve seat portion 97. The valve body 91 is provided with a perforated disk-shaped disc 104 on the opposite side to the piston body 83. The disc 104 has a smaller outer diameter than the disc 101 at the end of the valve body 91 on the side opposite to the piston main body 83. The disc 104 on the side opposite to the valve body 91 is provided with a perforated disc-like disc 105. The disk 105 has a larger outer diameter than the disk 104. A mounting shaft 72 is fitted to the inner periphery of the disks 103 to 105.

The valve body 91 can be detached from and seated on the valve seat portion 97. The valve body 91 can open the passage in the first passage hole 88 to the lower chamber 32 by being separated from the valve seat portion 97, and allows the flow of oil from the upper chamber 31 to the lower chamber 32. Suppress. The disc 101 in contact with the valve seat portion 97 in the valve body 91 has a notch 107 formed on the outer peripheral side. The cutout portion 107 and the valve seat portion 97 constitute a fixed orifice 106. The fixed orifice 106 allows the upper chamber 31 and the lower chamber 32 to communicate with each other even when the disk 101 is in contact with the valve seat portion 97. The disk 105 suppresses deformation beyond the regulation in the opening direction of the valve body 91.

The passage in the first passage hole 88 on the extension side provided in the piston main body 83, the fixed orifice 106, and the gap between the valve body 91 and the valve seat portion 97 at the time of the seating are separated by the piston 30 in the extension stroke. An extension-side passage 108 through which the oil liquid flows from the upper chamber 31 toward the lower chamber 32 by movement is formed. The expansion-side damping force generation mechanism 90 is provided in the contraction-side passage 108 and generates a damping force.

The valve body 93 is configured by stacking a plurality of perforated disk-shaped disks 111. The valve body 93 has the largest outer diameter of the disk 111 on the piston body 83 side, and the outer diameter of the disk 111 on the opposite side to the piston body 83 is smaller than this. Further, the outer diameter of the disk 111 at the intermediate portion in the stacking direction is the intermediate diameter of the respective disks 111 at both ends in the stacking direction. A mounting shaft 72 is fitted to the inner periphery of these disks 111. The valve body 93 is in contact with the valve seat 99 of the piston body 83 by the disk 111 closest to the piston body 83 to open and close the passage in the second passage hole 89.

Between the valve body 93 and the piston main body 83, a plurality of perforated disc-shaped disks 113 are provided. The outer diameter of each disk 113 is the same diameter and is smaller than the inner diameter of the valve seat portion 99. The valve body 93 is provided with a perforated disk-shaped disk 114 on the side opposite to the piston body 83. The disk 114 has a smaller outer diameter than the disk 111 at the end of the valve body 93 opposite to the piston body 83. The disc 114 is provided with a plurality of perforated disc-shaped discs 115 on the side opposite to the valve body 93. The plurality of disks 115 have the same outer diameter, and the outer diameter is larger than that of the disk 114. On the opposite side of the disk 115 from the disk 114, a perforated disk-shaped disk 116 is provided. The outer diameter of the disk 116 is smaller than that of the disk 115. A mounting shaft 72 is fitted to the inner peripheral portions of the disks 113 to 116.

The valve body 93 can be detached from and seated on the valve seat portion 99. The valve body 93 can open the passage in the second passage hole 89 to the upper chamber 31 by separating from the valve seat portion 99, and allows the flow of oil from the lower chamber 32 to the upper chamber 31. Suppress. In the valve body 93, a notch 118 is formed on the outer peripheral side of the disk 111 in contact with the valve seat portion 99. The notch 118 and the valve seat 99 constitute a fixed orifice 117. The fixed orifice 117 allows the upper chamber 31 and the lower chamber 32 to communicate with each other even when the disk 111 is in contact with the valve seat portion 99. The disc 115 suppresses deformation beyond the regulation in the opening direction of the valve body 93.

The passage in the second passage hole 89 on the contraction side provided in the piston main body 83, the fixed orifice 117, and the clearance between the valve body 93 and the valve seat portion 99 at the time of the separation are the positions of the piston 30 in the contraction stroke. A contraction-side passage 119 from which the oil liquid flows from the lower chamber 32 toward the upper chamber 31 by the movement is formed. The contraction-side damping force generating mechanism 92 is provided in the contraction-side passage 119 and generates a damping force.

A valve mechanism 131 is provided on the mounting shaft 72 of the tip rod 55 adjacent to the disc 116 on the side opposite to the valve body 93. The valve mechanism 131 constitutes the piston 30 together with the piston main body 83. The valve mechanism 131 includes a case body 132, a passage forming member 133, a valve body 134 (second valve body), a seat member 135, an O-ring 136, and a valve body 137.

The case body 132 has a perforated disc-shaped bottom plate portion 141 and a cylindrical tubular portion 142 extending in the axial direction from the outer peripheral side of the bottom plate portion 141. A mounting shaft portion 72 is fitted to the inner peripheral portion of the bottom plate portion 141. In the case body 132, the bottom plate portion 141 is in contact with the disk 116, and the cylindrical portion 142 extends from the bottom plate portion 141 in the direction opposite to the disk 116.

The passage forming member 133 is disposed in the cylindrical portion 142 of the case body 132. The passage forming member 133 includes a cylindrical passage forming portion 145 and an annular inner flange portion 146 that protrudes radially inward from one axial end side of the passage forming portion 145. The attachment shaft portion 72 is fitted to the inner peripheral portion of the inner flange portion 146, and the passage forming portion 145 is in contact with the bottom plate portion 141 of the case body 132. A passage groove 147 penetrating in the radial direction is formed in the passage forming portion 145. The passage groove 75 of the attachment shaft portion 72 crosses the bottom plate portion 141 of the case body 132 and opens at a position between the inner flange portion 146 and the bottom plate portion 141.

The sheet member 135 has an annular shape, and the mounting shaft portion 72 is fitted to the inner peripheral portion. The sheet member 135 is disposed in the cylindrical portion 142 of the case body 132 and is disposed on the opposite side of the valve body 134 from the passage forming member 133. The sheet member 135 has an O-ring 136 attached to the outer peripheral portion thereof, and is fitted into the cylindrical portion 142 of the case body 132 at the outer peripheral portion. At that time, the O-ring 136 seals the gap between the sheet member 135 and the case body 132. The sheet member 135 is formed between the case body 132 and an intermediate chamber 150 that is partitioned from the upper chamber 31.

The sheet member 135 communicates a plurality of first passage holes 151 that allow the upper chamber 31 and the intermediate chamber 150 to communicate with each other (only one location is shown in the cross-sectional view in FIG. 2), and the upper chamber 31 and the intermediate chamber 150. A plurality of second passage holes 152 (only one place is shown in FIG. 2 because of the cross section) are provided.
The first passage holes 151 are formed at an equal pitch in the circumferential direction with one second passage hole 152 interposed between the first passage holes 151, and one axial direction side of the sheet member 135 (FIG. 2). 2) is opened radially outward, and the other axial side (lower side in FIG. 2) is opened radially inward.

A damping force generation mechanism 155 including a valve body 134 that generates a damping force is provided for each first passage hole 151. The valve body 134 of the damping force generation mechanism 155 is disposed on the intermediate chamber 150 side on one end side in the axial direction of the seat member 135 and is attached to the piston rod 41. The passage in the first passage hole 151 is an extension-side passage through which oil passes when the piston rod 41 and the piston 30 move to the extension side (the upper side in FIG. 2). The damping force generation mechanism 155 provided for each first passage hole 151 generates an extension-side damping force that suppresses the flow of oil in the passage in the extension-side first passage hole 151 and generates a damping force. It is a mechanism.

In addition, the second passage hole 152 constituting the remaining half of the plurality of passage holes 151, 152 has one first passage hole 151 sandwiched between the second passage holes 152 in the circumferential direction, etc. The other side of the sheet member 135 in the axial direction (the lower side in FIG. 2) opens radially outward, and one side in the axial direction (the upper side in FIG. 2) opens radially inward.

A damping force generation mechanism 156 including a valve body 137 that generates a damping force is provided for each second passage hole 152. The valve body 137 of the damping force generation mechanism 156 is disposed on the opposite side to the intermediate chamber 150, which is the other end side of the seat member 135 in the axial direction, and is attached to the piston rod 41. The passage in the second passage hole 152 is a passage on the contraction side through which the oil liquid passes when the piston rod 41 and the piston 30 move to the contraction side (the lower side in FIG. 2). A damping force generation mechanism 156 provided for each second passage hole 152 suppresses the flow of oil in the passage in the second passage hole 152 on the contraction side and generates a damping force on the compression side. The mechanism is configured.

At the end of the seat member 135 on the intermediate chamber 150 side in the axial direction, an annular valve seat 161 is formed on the outer side in the radial direction than the opening of the first passage hole 151 on the intermediate chamber 150 side. The valve seat portion 161 and the valve body 134 constitute a damping force generation mechanism 155. In addition, an annular valve seat 162 is formed at the end of the seat member 135 opposite to the axial intermediate chamber 150 on the outer side in the radial direction than the opening of the second passage hole 152 on the upper chamber 31 side. ing. The valve seat portion 162 and the valve body 137 constitute a damping force generation mechanism 156.

In the seat member 135, the outer side in the radial direction of the valve seat portion 161 is formed in a step shape whose axial direction height is lower than that of the valve seat portion 161, and in the second passage hole 152 on the contraction side in this step shape portion. An opening on the intermediate chamber 150 side is arranged. Similarly, in the seat member 135, the outer side in the radial direction of the valve seat portion 162 is formed in a stepped shape having a lower axial height than the valve seat portion 162, and the stepped portion is extended to the second portion on the extending side. An opening on the upper chamber 31 side in the one passage hole 151 is arranged.

The valve element 134 is configured by stacking a plurality of perforated disk-shaped disks 171. In the valve body 134, the outer diameter of the disk 171 closest to the sheet member 135 is the largest, and the outer diameter of the disk 171 opposite to the sheet member 135 is smaller than this. Further, the outer diameter of the disk 171 at the intermediate portion in the stacking direction is the intermediate diameter of each disk at both ends in the stacking direction. The mounting shaft portion 72 is fitted to the inner peripheral portions of the plurality of disks 171. The valve body 134 abuts on the valve seat portion 161 of the seat member 135 with the disc 171 closest to the seat member 135 to open and close the passage in the first passage hole 151.

A plurality of perforated disc-shaped discs 173 are provided between the valve body 134 and the seat member 135. The outer diameter of each disk 173 is the same, and is smaller than the inner diameter of the valve seat portion 161. A plurality of perforated disc-shaped disks 174 are provided on the opposite side of the valve body 134 from the sheet member 135. The outer diameter of each disk 174 is the same, and is smaller than the disk 171 at the end opposite to the seat member 135 of the valve body 134. On the opposite side of the disc 174 from the valve body 134, a plurality of perforated disc-shaped discs 175 are provided. The plurality of disks 175 have the same outer diameter, and the outer diameter is larger than that of the disk 174. A mounting shaft 72 is fitted to the inner peripheral portions of these disks 173 to 175.

The valve element 134 can be detached from and seated on the valve seat portion 161. The valve body 134 can open the passage in the first passage hole 151 to the intermediate chamber 150 by separating from the valve seat portion 161. The valve body 134 suppresses the flow of oil from the upper chamber 31 to the intermediate chamber 150 while allowing it. A notch 177 is formed on the outer peripheral side of the disc 171 in contact with the valve seat 161 in the valve body 134. The notch 177 and the valve seat 161 constitute a fixed orifice 176. The fixed orifice 176 allows the upper chamber 31 and the intermediate chamber 150 to communicate with each other even when the disk 171 is in contact with the valve seat portion 161. The disk 175 suppresses deformation beyond the regulation in the opening direction of the valve body 134.

The valve body 137 is configured by stacking a plurality of perforated disc-shaped disks 181. In the valve body 137, the outer diameter of the disk 181 closest to the seat member 135 is the largest, and the outer diameter of the disk 181 opposite to the seat member 135 is smaller than this. Further, the outer diameter of the disk 181 at the intermediate portion in the stacking direction is the intermediate diameter of the respective disks at both ends in the stacking direction. A mounting shaft 72 is fitted to the inner periphery of these disks 181. The valve body 137 contacts the valve seat portion 162 of the seat member 135 with the disk 181 closest to the seat member 135 to open and close the passage in the second passage hole 152.

Between the valve body 137 and the seat member 135, a plurality of perforated disc-shaped disks 183 are provided. The outer diameter of each disk 183 is the same diameter and is smaller than the inner diameter of the valve seat portion 162. A plurality of discs 184 are provided on the opposite side of the valve body 137 from the sheet member 135. The outer diameter of each disk 184 is the same diameter, and is smaller than the disk 181 at the end of the valve body 137 opposite to the seat member 135.
The disk 184 is provided with a perforated disk-shaped disk 185 on the side opposite to the valve body 134. The outer diameter of the disk 185 is larger than that of the disk 184. The disk 185 is provided with an annular ring member 186 on the side opposite to the disk 184. The outer diameter of the annular member 186 is smaller than that of the disk 185. A mounting shaft 72 is fitted to the inner peripheral portions of the disks 183 to 185 and the annular member 186. The annular member 186 is in contact with the shaft step portion 73 of the tip rod 55.

The valve body 137 can be detached from and seated on the valve seat portion 162. The valve body 137 can open the passage in the second passage hole 152 to the upper chamber 31 by separating from the valve seat portion 162. The valve body 137 suppresses the oil liquid from the intermediate chamber 150 to the upper chamber 31 while allowing it to flow. In the valve body 137, a notch 188 is formed on the outer peripheral side of the disk 181 that contacts the valve seat portion 162. The cutout portion 188 and the valve seat portion 162 constitute a fixed orifice 187. The fixed orifice 187 allows the upper chamber 31 and the intermediate chamber 150 to communicate with each other even when the disk 181 is in contact with the valve seat portion 162. The disk 185 suppresses deformation beyond the regulation in the opening direction of the valve body 137.

As shown in FIG. 3, the frequency sensitive portion 200 is provided on the mounting shaft portion 72 of the tip rod 55 adjacent to the opposite side of the disc 105 from the valve body 91. The frequency sensitive unit 200 is configured to make the damping force variable in response to the frequency of reciprocation of the piston 30 (hereinafter referred to as the piston frequency) during the extension stroke.

The frequency sensitive unit 200 includes, in order from the axial disk 105 side, a case member 201, a passage forming disk 202, a plurality of disks 203 and a valve body (third valve body) 204, a plurality of sheet disks 205, And a lid member 206. The case member 201 has a bottomed cylindrical shape, and the attachment shaft portion 72 of the tip rod 55 is fitted to the inner peripheral portion. The passage forming disc 202, the plurality of discs 203, the plurality of sheet discs 205, and the lid member 206 are all in the shape of a perforated disk with a constant thickness, and are attached as shaft portions of the tip rod 55 to the inner peripheral portion The shaft portion 72 is fitted. A portion of the attachment shaft portion 72 that is disposed in the case member 201 constitutes the frequency sensitive portion 200. The valve body 204 has an annular shape, and is disposed in the case member 201 with the attachment shaft portion 72 penetrating inside. The lid member 206 is fitted to the case member 201, and the lid member 206 and the case member 201 constitute a housing 210.

The case member 201 includes a perforated disk-shaped base 221 along the direction orthogonal to the axis, an annular projecting portion 220, a cylindrical inner cylindrical portion 222, a cylindrical sheet portion 223, and an annular cylindrical shape. The cylindrical part 224 is provided. The annular projecting portion 220 projects from the inner peripheral side of the base portion 221 to one side in the axial direction. The inner cylindrical portion 222 protrudes from the inner peripheral side of the base portion 221 to the other side in the axial direction. The seat portion 223 protrudes from the intermediate position in the radial direction of the base portion 221 to the same side as the inner cylindrical portion 222. The cylindrical portion 224 extends from the outer peripheral edge portion of the base portion 221 to the same side as the sheet portion 223.

A small-diameter hole 225 is formed in the inner peripheral portion of the case member 201, and a large-diameter hole 226 having a larger diameter than the small-diameter hole 225 is formed on the inner cylindrical portion 222 side in the axial direction. The small-diameter hole portion 225 is formed so that the attachment shaft portion 72 of the tip rod 55 is fitted on the annular projecting portion 220 side in the axial direction. The passage groove 75 of the attachment shaft 72 is opened in the large diameter hole 226 across the small diameter hole 225. The passage groove 75 includes a bottom plate portion 141, a disc 116, a plurality of discs 115, a disc 114, a valve body 93, a plurality of discs 113, a piston main body 83, a plurality of discs 103, a valve of the case body 132 shown in FIG. The body 91, the disk 104, the disk 105, and the small diameter hole 225 of the case member 201 shown in FIG.

In the case member 201, the annular protrusion 220 is in contact with the disk 105, and the inner cylindrical portion 222 is in contact with the inner peripheral side of the passage forming disk 202. The seat portion 223 of the case member 201 supports the valve body 204 at the end portion on the protruding front end side of the seat portion 223. A cutout portion 231 is formed in the sheet portion 223. The notch 231 is partially formed in the circumferential direction and penetrates in the radial direction. By the cutout portion 231, the radially inner side and the radially outer side of the sheet portion 223 in the case member 201 are always in communication.

The passage forming disc 202 is disposed in the cylindrical portion 224 of the case member 201. The outer diameter of the passage forming disk 202 is larger than the portion of the inner cylindrical portion 222 in contact with the inner cylindrical portion 222 and smaller than the inner diameter of the sheet portion 223. The passage forming disk 202 has a notch 232 formed on the inner peripheral side. The notch 232 crosses the contact portion of the inner cylindrical portion 222 with the passage forming disk 202 in the radial direction. The plurality of disks 203 are arranged in the cylindrical portion 224 of the case member 201. The outer diameters of the respective disks 203 are the same, and are smaller than the outer diameter of the passage forming disk 202.

The valve body 204 is disposed in the cylindrical portion 224 of the case member 201, and includes a metal base disk 235 and a rubber seal member 236 fixed to the outer peripheral side of the base disk 235. The valve body 204 is configured to be elastically deformable, that is, bendable. The base disk 235 has a perforated circular flat plate shape with a constant thickness, and the inner diameter is larger than the outer diameter of the disk 203. As a result, the base disk 235 is configured to be arranged with a gap in the radial direction with respect to the disk 203 inside the base disk 235. The base disk 235 is thinner than the combined thickness of the plurality of disks 203. The outer diameter of the base disk 235 is larger than the outer diameter of the sheet portion 223 of the case member 201.

The seal member 236 is fixed to the outer peripheral side of the base disk 235. The seal member 236 is an elastic body, and has a cylindrical seal body 238 and a plurality of protrusions 239. The seal body 238 protrudes from the base disk 235 to the side opposite to the axial lid member 206. The plurality of projecting portions 239 project from the base disk 235 toward the lid member 206 in the axial direction. The seal member 236 connects the seal body 238 and the plurality of protrusions 239 at the outer periphery of the base disk 235, and in this state, the seal body 238 and the plurality of protrusions 239 are both surfaces of the base disk 235. It is fixed to. The outer diameter of the base disk 235 is smaller than the inner diameter of the cylindrical portion 224 of the case member 201. Therefore, an annular gap is provided between the base disk 235 and the case member 201. The seal member 236 connects the seal body 238 and the protrusion 239 through this gap. With such a configuration, the sealing member 236 can be easily fixed to the base disk 235.

The seal body 238 has an inner diameter at the end on the base disk 235 side, that is, a minimum inner diameter, larger than the outer diameter of the seat portion 223. Accordingly, the valve body 204 is configured such that the base disk 235 can be seated on the seat portion 223 of the case member 201. The plurality of protrusions 239 are arranged at intervals in the circumferential direction of the base disk 235. A radial groove 241 penetrating in the radial direction is formed between adjacent protrusions 239. In addition, since the notch part 231 is provided in the seat part 223, the pressure receiving area on the side where the seal main body part 238 of the valve body 204 is provided and the side where the protruding part 239 is provided are approximately the same.

The plurality of sheet disks 205 are arranged in the cylindrical portion 224 of the case member 201. The outer diameter of the sheet disk 205 closest to the disk 203 is the smallest, and the outer diameter of the sheet disk 205 on the opposite side of the disk 203 is larger than this. Further, the outer diameter of the sheet disk 205 at the intermediate portion in the stacking direction is the intermediate diameter of the respective disks at both ends in the stacking direction. The outer diameter of the sheet disk 205 closest to the disk 203 is larger than the outer diameter of the disk 203 and the inner diameter of the base disk 235. The base disc 235 of the valve body 204 is disposed between the passage forming disc 202 and the seat disc 205, and the thickness of the base disc 235 is thicker than the axial distance between the seat disc 205 and the seat portion 223. As a result, the valve body 204 is supported with the radially intermediate portion in contact with the seat portion 223, and the inner peripheral side is in contact with and supported by the seat disk 205.

In the valve body 204, the inner peripheral side of the base disk 235 is configured to be movable in the axial direction between the passage forming disk 202 and the sheet disk 205. Further, the valve body 204 is provided with an annular seal member 236 that seals between the valve member 204 and the case member 201 on the outer peripheral side which is the non-support side. The seal member 236 contacts the housing 210 and is centered with respect to the housing 210. The inner peripheral side of the valve body 204 has a simple support structure in which the sheet disc 205 is supported only on one side without being clamped from both sides.

The lid member 206 has a perforated disk shape, and the attachment shaft portion 72 of the tip rod 55 is fitted inside. Further, the outside of the lid member 206 is fitted in the cylindrical portion 224 of the case member 201. The lid member 206 is formed with a plurality of through holes 247 penetrating in the axial direction outward in the radial direction from the sheet disk 205. The plurality of through holes 247 are formed radially outside the seat disk 205 in the lid member 206, and are radially inward from the seal member 236 that contacts the lid member 206 when the base disk 235 is bent. Is formed.

The seal body 238 of the valve body 204 is in contact with the inner peripheral surface of the tubular portion 224 of the case member 201 over the entire circumference, and seals the gap between the valve body 204 and the tubular portion 224. That is, the valve body 204 is a packing valve. The seal main body 238 always seals the gap between the valve body 204 and the cylindrical portion 224 even if the valve body 204 is deformed within a range allowed in the housing 210. The valve body 204 is centered with respect to the housing 210 as described above when the seal body 238 contacts the cylindrical portion 224 over the entire circumference.

The valve body 204 divides the inside of the housing 210 into a variable volume variable chamber 245 on the base 221 side of the case member 201 and a variable volume variable chamber 246 on the lid member 206 side. In other words, the frequency sensitive unit 200 has two

variable chambers

245 and 246 in the case member 201 defined by the valve body 204. The variable chamber 246 always communicates with the lower chamber 32 through a passage in the through hole 247 of the lid member 206.

When the pressure in the variable chamber 245 is higher than the pressure in the variable chamber 246, the base disc 235 abuts the seat disc 205 over the entire circumference and does not form a gap between the valve disc 204 and the seat disc 205. Therefore, the flow of oil from the variable chamber 245 to the variable chamber 246 is restricted. Further, when the pressure in the variable chamber 246 is higher than the pressure in the variable chamber 245, the valve disc 204 is separated from the seat disc 205 to form a gap between the base disc 235 and the variable disc 246. That is, the flow of the oil liquid from the lower chamber 32 to the variable chamber 245 is allowed. The valve body 204 and the seat disk 205 constitute a check valve 248.

2 includes a passage in the first passage hole 151 of the seat member 135, a fixed orifice 176, a gap between the valve body 134 and the valve seat portion 161 at the time of separation, and a passage in the passage groove 147 of the passage forming member 133. The passage in the passage groove 75 of the intermediate chamber 150, the tip rod 55, the passage in the large-diameter hole portion 226 of the case member 201 shown in FIG. 3, and the passage in the notch 232 of the passage formation disk 202 are extended passages. 251 (second passage) is formed. The extension-side passage 251 is a passage through which oil liquid flows from the upper chamber 31 toward the variable chamber 245 by the movement of the piston 30 in the extension stroke.

The passage in the through-hole 247 of the lid member 206, the variable chamber 246, the gap between the valve body 204 and the seat disc 205 at the time of separation, the passage in the notch 232 of the variable chamber 245 and the passage formation disc 202, the case member 201 The passage in the large-diameter hole portion 226, the passage in the passage groove 75 of the tip rod 55, the passage in the second passage hole 152 of the seat member 135 shown in FIG. 2, the fixed orifice 187, and the seating position A gap between the valve body 137 and the valve seat portion 162 forms a contraction-side passage 252. The contraction-side passage 252 is a passage through which oil liquid flows from the lower chamber 32 toward the upper chamber 31 by the movement of the piston 30 in the contraction stroke. The passages in the passage groove 75 of the intermediate chamber 150 and the tip rod 55 are common to the

passages

251 and 252.

In the passage 251, a damping force generation mechanism 155 including the valve body 134 and a frequency sensitive unit 200 including the valve body 204 shown in FIG. 3 are provided in series. The valve body 134 (see FIG. 2) of the damping force generation mechanism 155 provided in the passage 251 is similar to the passage 251 in the extension stroke, and the damping force generation mechanism 90 provided in the passage 108 from which the oil liquid flows out from the upper chamber 31 in the extension stroke. The valve is opened with a pressure smaller than that of the valve body 91 to generate a damping force. That is, the valve body 134 has lower rigidity than the valve body 91. Of the damping

force generation mechanisms

90 and 155, the damping force generation mechanism 155 is a soft valve, and the damping force generation mechanism 90 is a hard valve.

The valve body 137 of the damping force generation mechanism 156 provided in the passage 252 is a damping force generation mechanism 92 provided in the passage 119 through which the oil liquid flows from the lower chamber 32 toward the upper chamber 31 in the contraction stroke. The valve body 93 is opened with a pressure smaller than that of the valve body 93 to generate a damping force. That is, the valve body 137 has lower rigidity than the valve body 93. Of the damping

force generation mechanisms

92 and 156, the damping force generation mechanism 156 is a soft valve, and the damping force generation mechanism 92 is a hard valve.

The frequency sensitive unit 200 shown in FIG. 3 provided in the passage 251 moves when the piston 30 moves to the upper chamber 31 side shown in FIG. 2 and the oil liquid flows from the upper chamber 31 toward the lower chamber 32. The pressure in the variable chamber 245 shown in FIG. 2 becomes higher than the pressure in the variable chamber 246 on the downstream side. As a result, the valve body 204 of the check valve 248 is seated and closed on the seat disk 205, and the housing 210 is divided into an upstream variable chamber 245 and a downstream variable chamber 246, while the housing 210 is within the housing 210. The variable chamber 245 is expanded and moved so as to narrow the variable chamber 246. As a result, the frequency sensitive unit 200 can vary the damping force according to the frequency.

Further, the frequency sensitive unit 200 moves in the variable chamber 245 shown in FIG. 3 when the piston 30 moves to the lower chamber 32 side and the oil liquid flows from the lower chamber 32 toward the upper chamber 31 shown in FIG. The pressure in the variable chamber 246 is higher than the pressure in the first chamber. As a result, the valve body 204 of the check valve 248 opens and is separated from the seat disk 205. As a result, the check valve 248 opens the passage 252 and the oil liquid flows out from the lower chamber 32 toward the upper chamber 31.

The lid member 206 is provided with a plurality of perforated disk-shaped disks 255 on the opposite side to the sheet disk 205. The outer diameter of each disk 255 is the same, and is smaller than the inscribed circle of the plurality of through holes 247 in the radial direction of the lid member 206. Each disk 255 is provided with an annular member 256 on the side opposite to the lid member 206. The annular member 256 has an outer diameter larger than that of the disk 255. A mounting shaft portion 72 is fitted to the inner peripheral portions of the disk 255 and the annular member 256. The annular member 256 is provided with a nut 260 on the side opposite to the disk 255 and screwed to the male screw 76 of the mounting shaft portion 72.

The annular member 186, the disk 185, the plurality of disks 184, the valve body 137, the plurality of disks 183, the sheet member 135, the plurality of disks 173, the valve body 134, the plurality of disks 174, the plurality of sheets shown in FIG. Disc 175, passage forming member 133, bottom plate portion 141 of case body 132, disc 116, discs 115, disc 114, valve body 93, discs 113, piston body 83, discs 103, valve The body 91, the

disks

104 and 105, the case member 201, the passage forming disk 202, the plurality of disks 203, the plurality of sheet disks 205, the lid member 206, the plurality of disks 255, and the annular member 256 shown in FIG. Each of the inner peripheral side or all of the shaft step 73 of the tip rod 55 shown in FIG. It is sandwiched and bets 260 is clamped in the axial direction. On the other hand, neither the inner peripheral side nor the outer peripheral side of the valve body 204 is clamped in the axial direction. The nut 260 is a general-purpose hex nut.

FIG. 4 shows a hydraulic circuit diagram of the shock absorber 11 according to the first embodiment. That is, a damping force generation mechanism 90 that is a hard valve is provided in a passage 108 that connects the upper chamber 31 and the lower chamber 32, and a damping force generation mechanism 92 that is a hard valve is provided in a passage 119 that connects the upper chamber 31 and the lower chamber 32. The fixed

orifices

106 and 117 are provided in the

passages

108 and 119, respectively.
Further, a damping force generation mechanism 155 that is a soft valve is provided in the passage 251 between the upper chamber 31 and the intermediate chamber 150, and a damping force generation mechanism 156 that is a soft valve is provided in the passage 252 between the upper chamber 31 and the intermediate chamber 150. Are provided, and fixed

orifices

176 and 187 are provided in the

passages

251 and 252, respectively.

Further, a frequency sensitive unit 200 is provided between the intermediate chamber 150 and the lower chamber 32. When the oil solution flows from the upper chamber 31 toward the lower chamber 32, the frequency sensitive unit 200 closes the check valve 248 to define the

variable chambers

245 and 246, and supplies the oil solution from the intermediate chamber 150 to the variable chamber 245. accept. Thereby, the damping force is varied according to the frequency. Further, when the oil solution flows from the lower chamber 32 toward the upper chamber 31, the frequency sensitive unit 200 opens the check valve 248 and causes the oil solution to flow from the lower chamber 32 to the intermediate chamber 150.

The characteristic of the damping force with respect to the piston speed when only the damping force generating mechanism 90 acts in the extension stroke in which the piston rod 41 moves to the extension side is shown by a broken line X1 in FIG. When only the damping force generating mechanism 90, which is the hard valve on the extension side shown in FIG. 2, acts in the extension stroke in which the piston rod 41 moves to the extension side, the moving speed of the piston 30 (hereinafter referred to as “piston speed”). When the oil pressure from the upper chamber 31 is low, the fluid from the upper chamber 31 flows into the lower chamber 32 through the passage in the first passage hole 88 and the fixed orifice 106 constituting the passage 108, and the orifice characteristic (damping force is changed to the piston). A damping force is generated that is approximately proportional to the square of the velocity. Therefore, the characteristic of the damping force with respect to the piston speed is such that the rate of increase of the damping force is higher with respect to the increase of the piston speed in the low speed region (orifice region) on the left end side in FIG. 5, as indicated by the broken line X1 in FIG. Become. Further, when the piston speed increases, the oil from the upper chamber 31 opens the valve body 91 of the damping force generating mechanism 90 on the extension side from the passage in the first passage hole 88 that constitutes the passage 108, while the valve body is opened. Flow between 91 and the valve seat portion 97 flows into the lower chamber 32, and a damping force having a valve characteristic (a damping force is substantially proportional to the piston speed) is generated. For this reason, in the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force is slightly lower than the low speed region (orifice region) with respect to the increase in piston speed.

The characteristic of the damping force with respect to the piston speed when only the contraction-side damping force generating mechanism 92 acts in the contraction stroke in which the piston rod 41 moves to the contraction side is shown by a broken line X2 in FIG. In the contraction stroke in which the piston rod 41 moves to the contraction side, when only the contraction-side damping force generation mechanism 92 acts, when the piston speed is low, the oil liquid from the lower chamber 32 passes through the contraction-side passageway 119. A damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated in the upper chamber 31 through the passage in the second passage hole 89 and the fixed orifice 117. For this reason, the characteristic of the damping force with respect to the piston speed is, as shown by a broken line X2 in FIG. 5, in the low speed region (orifice region) on the left end side in FIG. Becomes higher. Further, when the piston speed is increased, the oil introduced into the passage in the second passage hole 89 constituting the contraction-side passage 119 from the lower chamber 32 basically opens the valve body 93 while opening the valve body 93 and the valve. Flowing between the seat portion 99 and the upper chamber 31, a damping force having a valve characteristic (a damping force is approximately proportional to the piston speed) is generated. For this reason, in the characteristic of the damping force with respect to the piston speed, the rate of increase of the damping force with respect to the increase of the piston speed is slightly lower than the low speed region (orifice region).

The above is the case where only the damping

force generation mechanisms

90 and 92 shown in FIG. 2 act, but in the first embodiment, the frequency sensitive unit 200 shown in FIG. 3 responds to the piston frequency even when the piston speed is the same. The damping force is variable.

That is, in the extension stroke when the piston frequency is high, when only the damping force generation mechanism 90 acts as described above when the piston speed is low, the upper chamber 31 even in the orifice region flowing through the fixed orifice 106. Is introduced from the passage in the first passage hole 151 into the variable chamber 245 of the frequency sensitive unit 200 through the fixed orifice 176, the intermediate chamber 150, and the passage in the passage groove 75. Accordingly, while the valve body 204 that has been in contact with the seat portion 223 and the seat disk 205 is deformed so that the protruding portion 239 approaches the lid member 206 and oil is introduced into the variable chamber 245, Oil is discharged from the variable chamber 246 to the lower chamber 32 through a passage in the through hole 247 of the lid member 206.

In this manner, the valve body 204 is deformed and the oil liquid is introduced into the variable chamber 245 from the upper chamber 31, whereby the flow rate of the oil liquid flowing from the upper chamber 31 through the passage 108 to the lower chamber 32 is reduced.
For this reason, the characteristic of the damping force with respect to the piston speed is as shown by a solid line X3 in FIG. 5, and the damping force on the extension side becomes softer from the low speed region (orifice region) on the left end side in FIG. Here, since the inner peripheral side of the valve body 204 is separated from the passage forming disc 202 and is supported only on one side by the seat disc 205, the inner peripheral side easily deforms so as to approach the passage forming disc 202. The outer peripheral projection 239 is easily deformed so as to approach the lid member 206.

When the piston speed increases slightly, the fluid from the upper chamber 31 opens the valve body 134 of the damping force generation mechanism 155 that is a soft valve on the extension side from the passage in the first passage hole 151, and the valve body 134 and the valve It passes between the sheet portion 161 and is introduced into the variable chamber 245 of the frequency sensitive portion 200 through the intermediate chamber 150 and the passage in the passage groove 75. Also at this time, since the valve body 204 is deformed to introduce the oil into the variable chamber 245, the flow rate of the oil flowing from the upper chamber 31 through the passage 108 to the lower chamber 32 is reduced. For this reason, the damping force on the extension side continues to be soft in the low speed region on the left end side in FIG.

When the piston speed is further increased, the oil liquid from the upper chamber 31 is introduced into the variable chamber 245 of the frequency sensing unit 200 by opening the valve body 134 of the damping force generation mechanism 155 that is a soft valve as described above. In addition, while opening the valve body 91 of the damping force generation mechanism 90 on the extension side from the passage in the first passage hole 88 constituting the passage 108, it passes between the valve body 91 and the valve seat portion 97, It flows to 32. For this reason, the characteristic of the damping force with respect to the piston speed is such that the extension side damping force is soft even in the middle to high speed range from the middle in the left-right direction in FIG.

In the extension stroke when the piston frequency is high, the frequency of deformation of the valve body 204 also increases and the oil liquid from the upper chamber 31 is supplied to the variable chamber 245 of the frequency sensing unit 200 as described above each time the extension stroke is performed. Introduce.

On the other hand, in the extension stroke when the piston frequency is low, the deformation frequency of the valve body 204 also follows and becomes low. For this reason, although the oil liquid flows from the upper chamber 31 to the variable chamber 245 in the initial stage of the extension stroke, the valve body 204 stops after contacting the lid member 206, and then the variable chamber is passed from the upper chamber 31 through the passage 251. The oil liquid does not flow to 245. As a result, the flow rate of the oil liquid that is introduced from the upper chamber 31 into the passage 108 including the passage in the first passage hole 88 and flows through the damping force generation mechanism 90 to the lower chamber 32 is not reduced, and the piston speed is reduced. The characteristics of the damping force are the same as when only the damping force generating mechanism 90 acts, and the extension side damping force becomes hard as indicated by the broken line X1 in FIG.

In this way, during the extension stroke, the characteristic when the piston frequency is high is the same as the characteristic when the piston frequency is high as shown by the solid line X3 in FIG. Soft from the low speed range (orifice range) to the high speed range.

In the contraction stroke, when the piston speed is low, the oil from the lower chamber 32 flows from the passage 119 to the upper chamber 31 through the fixed orifice 117, and on the other hand, the oil from the lower chamber 32 has a frequency. The valve body 204 constituting the check valve 248 in the sensitive unit 200 is separated from the seat disk 205, passes through the passage 252, and flows from the fixed orifice 187 to the upper chamber 31. Thereby, the characteristic of the damping force with respect to the piston speed becomes as shown by a solid line X4 in FIG. 5, and the damping force on the contraction side becomes soft from the low speed region (orifice region) on the left end side in FIG.

When the piston speed increases slightly, the oil from the lower chamber 32 passing through the passage 252 passes between the valve body 137 and the valve seat portion 162 while opening the valve body 137 of the damping force generation mechanism 156 that is a soft valve. And introduced into the upper chamber 31. As a result, a damping force of the valve characteristic is generated. Therefore, the damping force characteristic with respect to the piston speed is slightly reduced in the middle speed range of FIG. .

When the piston speed is further increased, the fluid from the lower chamber 32, in addition to the above flow through the passage 252, the flow of the passage 119 opens the valve body 93 of the damping force generation mechanism 92, It is introduced into the upper chamber 31 through the space between the valve seat 99. Thereby, the characteristic of the damping force with respect to the piston speed further decreases in the rate of increase of the damping force with respect to the increase of the piston speed in the high speed region on the right side of FIG.

That is, in the contraction stroke, the frequency sensitive unit 200 is not provided, and the hard valve damping force generation mechanism 92 and the soft valve damping force generation mechanism 156 are in parallel. With the structure in which these are arranged in parallel, the characteristic of the damping force with respect to the piston speed is as shown by a solid line X4 in FIG. 5, compared with the case where only the damping force generating mechanism 92 shown by the broken line X2 in FIG. The piston speed is soft from low speed range (orifice range) to high speed range. Here, a two-dot chain line X5 shown in FIG. 5 is a damping force characteristic when only the damping force generation mechanism 156 that is a soft valve is provided without the damping force generation mechanism 92 that is a hard valve.

Patent Document 1 described above describes a shock absorber provided with a damping force variable mechanism that varies the damping force according to the frequency. In the shock absorber, there is a demand to make the damping force largely variable according to the frequency from the region where the piston speed is low.

The shock absorber 11 according to the first embodiment is provided with a valve body 91 that generates a damping force in the passage 108 through which the oil liquid flows out of the upper chamber 31 by the movement of the piston 30. In addition, a valve body 134 that opens with a pressure smaller than the valve body 91 to generate a damping force in another passage 251 from which the oil liquid flows out from the upper chamber 31 by the movement of the piston 30, and the upper chamber 31 to the lower chamber 32. A valve that is movable in the housing 210 while defining the inside of the housing 210 into an upstream side and a downstream side when the oil liquid flows in the housing 210 and that can be opened when the oil liquid flows from the lower chamber 32 to the upper chamber 31. A frequency sensitive unit 200 having a body 204 is provided in series. As a result, the damping force can be varied greatly according to the frequency from the region where the piston speed is low.

Further, the upper chamber 31 is a rod side chamber and the lower chamber 32 is a bottom side chamber, and during the extension stroke, the valve body 204 moves in the housing 210 while defining the inside of the housing 210 into the upstream side and the downstream side. Thus, the damping force can be varied according to the frequency, and the valve body 204 can be opened during the contraction stroke. Thereby, it becomes possible to greatly vary the damping force according to the frequency from the region where the piston speed is slow in the extension stroke.

FIG. 6 is a Lissajous waveform that simulates the operation of the shock absorber 11 when the speed of the piston 30 is 0.03 m / s and shows the relationship between the piston stroke and the damping force. In FIG. 6, the operating frequency of the piston 30 increases from the outside toward the inside, and in the vicinity of the origin where the stroke of the piston 30 is small, the damping force at the high frequency is compared to the damping force at the low frequency. It can be seen that can be lowered as shown by the arrow Y1. FIG. 7 is a diagram showing the relationship between the frequency and the damping force at the time of simulating the operation when the speed of the piston 30 is 0.03 m / s. This result also shows that the damping force at the high frequency on the right side can be lowered as shown by the arrow Y2 with respect to the damping force at the low frequency on the left side in FIG.

FIG. 8 is a Lissajous waveform that simulates the operation of the shock absorber 11 when the speed of the piston 30 is 0.3 m / s and shows the relationship between the piston stroke and the damping force. Also in FIG. 8, the operating frequency of the piston 30 increases from the outside toward the inside, and in the vicinity of the origin where the stroke of the piston 30 is small, the damping force at the high frequency is compared with the damping force at the low frequency. It can be seen that can be lowered as shown by arrow Y3. FIG. 9 is a diagram showing the relationship between the frequency and the damping force at the time of simulating the operation when the speed of the piston 30 is 0.3 m / s. From this result, it can be seen that the damping force at the high frequency on the right side can be lowered as shown by the arrow Y4 with respect to the damping force at the low frequency on the left side in FIG.

The frequency sensitive unit 200 is configured to define

variable chambers

245 and 246 in the case member 201 with an annular elastically deformable valve body 204 provided with an annular seal member 236 for sealing between the case member 201 and the case. It is configured. With this configuration, the axial length can be shortened, and the overall basic length of the shock absorber 11 can be shortened and downsized.

Moreover, since the frequency sensitive part 200 has a skewer structure, the inner periphery of each of the piston 30 and the case member 201 of the frequency sensitive part 200 is fastened to the piston rod 41 with a general-purpose nut 260 in a state where the piston rod 41 is inserted. can do. Therefore, the piston 30 and the frequency sensitive part 200 can be easily fastened to the piston rod 41, and the assemblability is greatly improved. Further, the axial length can be shortened.

Further, since the inner peripheral side of the valve body 204 is supported only on one side without being clamped from both sides, the deformation becomes easy and the volumes of the

variable chambers

245 and 246 can be easily changed. Therefore, the damping force variable adjustment range of the frequency sensitive unit 200 can be widened.

Further, the frequency sensitive unit 200 that functions in the expansion stroke is provided, and the frequency sensitive unit that functions in the contraction stroke is not provided. For this reason, while suppressing the increase in cost, for example, by making the damping force variable in response to the piston frequency in the extension stroke, it is possible to improve the riding comfort for an effective road surface condition or the like. In addition, it is difficult to control the posture with a shock absorber having a frequency sensitive portion that makes the damping force variable in response to the piston frequency in the contraction stroke, and the frequency sensitive portion 200 that makes the damping force variable in response to the piston frequency in the extension stroke. The present invention is suitable for use in a vehicle capable of effectively controlling the attitude with a shock absorber.

(Second Embodiment)
Next, a second embodiment of the shock absorber according to the present invention will be described mainly based on FIGS. 10 to 12 with a focus on differences from the first embodiment. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

As shown in FIG. 10, in the second embodiment, a case member 201A is used instead of the case member 201 of the first embodiment. The case member 201A is different from the case member 201 of the first embodiment in that a cylindrical portion 224A having a longer axial length than the cylindrical portion 224 is provided. In addition, the lid member 206 is provided with a plurality of sheet disks 205 A similar to the sheet disk 205 in the opposite direction to the sheet disk 205 on the opposite side to the sheet disk 205. The seat disc 205A is provided with a plurality of discs 203A similar to the disc 203 and a valve disc 204A (fourth valve disc) similar to the valve disc 204 on the side opposite to the lid member 206. . The valve body 204 A is provided in series with the valve body 204 in the opposite direction to the valve body 204.

The lid member 281A is provided on the disc 203A and the valve body 204A on the opposite side to the seat disc 205A. The lid member 281 A is a member having an annular projecting portion 220, a base portion 221, an inner cylindrical portion 222, a sheet portion 223, and a notch portion 231 of the case member 201, and the cylindrical portion 224 is not provided. A plurality of through holes 282A are formed in the base 221 of the lid member 281A. The lid member 281A is fitted into the tubular portion 224A of the case member 201A with the seat portion 223 facing the valve body 204A, and the lid member 281A and the case member 201A constitute a tubular housing 210A.

The passage forming disk 202, the plurality of disks 203, the valve body 204, the plurality of sheet disks 205, the lid member 206, the plurality of sheet disks 205A, the plurality of disks 203A, and the valve body 204A are cylindrical shapes of the case member 201A. It is arranged in the part 224A. The lid member 281A is fitted in the cylindrical portion 224A of the case member 201A.

In 2nd Embodiment, it becomes the frequency sensitive part 200A similar to the frequency sensitive part 200 of 1st Embodiment, The base 221 of the case member 201A, the inner side cylindrical part 222, the sheet | seat part 223, and cylindrical shape 224 A and notch portion 231, passage forming disk 202, a plurality of disks 203, a valve body 204, a plurality of sheet disks 205, and a lid member 206.
Further, the lid member 206, the cylindrical portion 224A of the case member 201A, the plurality of sheet discs 205A, the plurality of discs 203A, the valve body 204A, and the lid member 281A provide another frequency sensitive portion 284A. It is composed. The portion of the mounting shaft 72 that is disposed in the case member 201A constitutes the frequency

sensitive portions

200A and 284A. The valve body 204A has an annular shape, and is disposed in the case member 201A with the attachment shaft portion 72 penetrating inward.

The valve body 204A is supported by the seat disk 205A on the inner peripheral side. The valve body 204A is configured such that the inner peripheral side of the base disk 235 is movable in the axial direction between the seat disk 205A and the lid member 281A. In addition, the valve body 204A is provided with an annular seal member 236 that seals between the case member 201A and the outer peripheral side which is the non-support side. The valve body 204A is centered with respect to the housing 210A when the seal member 236 contacts the housing 210A.
The inner peripheral side of the valve body 204A is a simple support structure that is supported by the sheet disk 205A only on one side without being clamped from both sides.

The seal body 238 of the valve body 204A contacts the inner peripheral surface of the cylindrical portion 224A of the case member 201A over the entire circumference, and seals the gap between the valve body 204A and the cylindrical portion 224A. The seal body 238 of the valve body 204A also always seals the gap between the valve body 204A and the cylindrical portion 224A even if the valve body 204A is deformed within the allowable range within the housing 210A. The valve body 204A is centered with respect to the housing 210A as described above when the seal main body portion 238 contacts the cylindrical portion 224A over the entire circumference.

The valve body 204A partitions the inside of the housing 210A into a variable volume variable chamber 245 on the base 221 side of the case member 201A and a variable volume variable chamber 246A between the

valve bodies

204 and 204A. The valve body 204A divides the inside of the housing 210A into a variable chamber 246A and a variable chamber 285A having a variable capacity on the lid member 281A side of the valve body 204A. In other words, the frequency sensitive part 284A has two

variable chambers

246A and 285A in the case member 201A defined by the valve body 204A. The variable chamber 285A is in continuous communication with the lower chamber 32 through a passage in the through hole 282A of the lid member 281A. The frequency sensitive part 284A is provided on the lower chamber 32 side of the valve body 204 of the frequency sensitive part 200A.

When the pressure in the variable chamber 285A is higher than the pressure in the variable chamber 246A, the valve disc 204A does not form a gap between the base disc 235 and the seat disc 205A due to contact with the seat disc 205A. Therefore, the flow of the oil liquid from the variable chamber 285A to the variable chamber 246A is restricted. Further, when the pressure in the variable chamber 246A is higher than the pressure in the variable chamber 285A, the valve disc 204A forms a gap between the base disk 235 and the seat disk 205A by separating from the seat disk 205A. To the variable chamber 285A, that is, the flow of the oil liquid to the lower chamber 32 is allowed. The valve body 204A and the seat disk 205A constitute a check valve 248A.

When the piston 30 moves to the upper chamber 31 side and the oil liquid flows from the upper chamber 31 toward the lower chamber 32, the frequency sensitive portion 200A causes the pressure of the variable chamber 245 to be lower than that of the variable chamber 246A on the downstream side. Higher than pressure. As a result, the valve body 204 of the check valve 248 is seated and closed on the seat disk 205, defining the inside of the housing 210A into the upstream variable chamber 245 and the downstream variable chamber 246A. The variable chamber 245A is expanded and moved so as to narrow the variable chamber 246A. At that time, even if the pressure in the variable chamber 246A increases, the frequency sensing unit 284A causes the valve body 204A of the check valve 248A to separate from the seat disk 205A and open the valve, thereby increasing the pressure in the variable chamber 246A. It suppresses and becomes that it becomes resistance of movement of valve element 204. As a result, the frequency sensitive unit 200A can vary the damping force according to the frequency, like the frequency sensitive unit 200 of the first embodiment.

When the piston 30 moves to the lower chamber 32 side and the oil liquid flows from the lower chamber 32 toward the upper chamber 31, the frequency sensitive portion 284A causes the pressure in the variable chamber 285A to be in the downstream variable chamber 246A. Higher than pressure. As a result, the valve body 204A of the check valve 248A is seated and closed on the seat disk 205A, and the housing 210A is defined as an upstream variable chamber 285A and a downstream variable chamber 246A. The variable chamber 285A can be expanded and the variable chamber 246A can be narrowed. At that time, even if the pressure in the variable chamber 246A increases, the frequency sensing unit 200A causes the valve body 204 of the check valve 248 to move away from the seat disk 205 and open, thereby increasing the pressure in the variable chamber 246A. It suppresses and becomes that it becomes resistance of movement of valve body 204A. As a result, the frequency sensitive unit 284A varies the damping force according to the frequency in the contraction stroke.

FIG. 11 shows a hydraulic circuit diagram of the second embodiment. That is, when the oil is flowing from the upper chamber 31 toward the lower chamber 32 in the extension stroke, the frequency sensing unit 200A closes the check valve 248 to define the

variable chambers

245 and 246A, and the damping force according to the frequency. Make it variable. Further, when the oil is flowing from the lower chamber 32 toward the upper chamber 31 in the contraction stroke, the frequency sensing unit 284A closes the check valve 248A to define the

variable chambers

285A and 246A, and the damping force according to the frequency. Make it variable.

In the second embodiment, in the contraction stroke when the piston frequency is high, the oil liquid from the lower chamber 32 is introduced into the variable chamber 285A of the frequency sensitive portion 284A even in a region where the piston speed is low. For this reason, the characteristic of the damping force with respect to the piston speed is as shown by a solid line X6 in FIG. 12, and the damping force becomes soft from the low speed region (orifice region) on the left end side in FIG.

In the second embodiment, the frequency having the valve body 204A that can move in the housing 210A while defining the inside of the housing 210A on the upstream side and the downstream side in the contraction stroke, and can open in the expansion stroke. A sensitive portion 284 A is provided on the lower chamber 32 side of the valve body 204. As a result, even in the contraction stroke, the damping force can be greatly varied according to the frequency from the region where the piston speed is low.

(Third embodiment)
Next, a third embodiment of the shock absorber according to the present invention will be described mainly on the difference from the first embodiment based on FIG. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

As shown in FIG. 13, in the third embodiment, a frequency sensitive unit 300 different from the stretched frequency sensitive unit 200 of the first embodiment is provided. Each of the frequency sensitive parts 300 includes a housing 303 including a perforated disk-like lid member 301 into which the attachment shaft part 72 is fitted and a bottomed cylindrical case member 302. The mounting shaft portion 72 disposed in the case member 302 also constitutes the frequency sensitive portion 300.

The lid member 301 is provided with a cylindrical sheet portion 305, and the sheet portion 305 is formed with a notch portion 306 that always communicates the inner peripheral side and the outer peripheral side of the sheet portion 305. On the inner peripheral side of the lid member 301, a small-diameter hole 307 that fits into the mounting shaft 72 and a large-diameter hole 308 that is larger in diameter than the small-diameter hole 307 are formed.

A valve body 311 (third valve body) is provided in the case member 302. The valve body 311 has a metal perforated disk-shaped disk 312 and a rubber elastic seal member 313 provided on the inner peripheral side of the disk 312 and has an annular shape. The valve body 311 can be bent, and is disposed in the case member 302 with the attachment shaft portion 72 penetrating inside.

The case member 302 has a perforated disk-shaped bottom portion 315 and a tubular portion 316 extending in the axial direction from the outer peripheral edge portion of the bottom portion 315, and the lid member 301 is fitted to the tubular portion 316. Yes. A through hole 317 that opens to the lower chamber is formed in the bottom 315 of the case member 302.

The step part 322 is formed in the inner peripheral side of the cylindrical part 316 of the case member 302 by providing the large diameter part 320 and the small diameter part 321. The step portion 322 supports the outer peripheral side of the valve body 311. The axial dimension between the step portion 322 and the sheet portion 143 is smaller than the thickness of the disk 312. Thereby, a set load can be applied to the valve body 311. The seal member 313 provided on the non-supporting side of the valve body 311 is provided on the attachment shaft portion 72 side of the tip rod 55 constituting the piston rod 41. A space between the valve body 311 and the tip rod 55 is sealed by an annular seal member 313.

In a state where the piston rod 41 is attached to the tip rod 55, the passage in the passage groove 75 of the tip rod 55 and the passage in the large-diameter hole 308 of the lid member 301 of the frequency sensing unit 300 communicate with each other. In the case member 302, two variable chambers 331 and a variable chamber 332 are defined by a valve body 311. A variable chamber 331 that communicates with the passage in the passage groove 75 and a variable chamber 332 that communicates with the lower chamber 32 through a passage in the through hole 317 are defined. The valve body 311 restricts the flow of oil from the variable chamber 331 to the variable chamber 332 by sitting on the stepped portion 322. Further, the valve body 311 is a check valve 333 that opens when the valve body 311 is separated from the stepped portion 322 and allows the flow of oil from the variable chamber 332 to the variable chamber 331.

In the frequency sensitive unit 300 of the third embodiment, the supporting side and the non-supporting side of the valve body 311 are reversed inside and outside the valve body 204 of the frequency sensitive unit 200 of the first embodiment. Are the same.

Note that the frequency sensitive portion 284A of the second embodiment also supports the valve body 204A on the outer peripheral side and seals between the mounting shaft portion 72 on the inner peripheral side, which is the non-support side, as in the third embodiment. You may make it the structure to do.

The embodiment described above can be considered as follows.

A first aspect includes a cylinder in which a working fluid is enclosed, a piston that is slidably fitted in the cylinder, and divides the cylinder into two chambers, a first chamber and a second chamber, and the piston. A piston rod that is connected and extends to the outside of the cylinder; a first passage and a second passage through which working fluid flows from one of the first chamber and the second chamber by the movement of the piston; and the first passage A second valve body that generates a damping force by opening the second passage with a pressure smaller than that of the first valve body. When the working fluid flows from the first chamber to the second chamber, it is movable in the housing while defining the inside of the housing on the upstream side and the downstream side, and from the second chamber to the first chamber 3rd valve body which can be opened when working fluid flows A frequency response unit having, but are provided in series. As a result, the damping force can be varied greatly according to the frequency from the region where the piston speed is low.

According to a second aspect, in the first aspect, the first chamber is a rod-side chamber, the second chamber is a bottom-side chamber, and the third valve body is upstream in the housing during an extension stroke. The damping force is varied according to the frequency by moving within the housing while defining the side and the downstream side, and the third valve body can be opened during the contraction stroke. As a result, in the extension stroke, the damping force can be varied greatly according to the frequency from the region where the piston speed is low.

A third aspect is the second aspect, in which the third valve body is defined on the second chamber side in the housing while the housing is defined as an upstream side and a downstream side during the contraction stroke. A frequency sensitive part having a fourth valve body that is movable and can be opened during the extension stroke is provided. As a result, in the contraction stroke, the damping force can be greatly varied according to the frequency from the region where the piston speed is low.

According to a fourth aspect, in any one of the first to third aspects, the frequency sensitive portion includes a cylindrical case member, a shaft portion disposed in the case member, and the shaft portion. An annular elastic seal member that is disposed in the case member, is supported on the inner or outer peripheral side, and seals between the case member or the shaft portion on the non-supporting side, so that it can be bent. The third valve body and two chambers in the case member defined and provided by the third valve body. Thereby, the axial length can be shortened, and the overall basic length can be shortened and miniaturized.

The embodiments of the present invention have been described above. However, the technical scope of the present invention is not limited to only the above-described embodiments, and combinations of components in the embodiments are changed without departing from the spirit of the present invention. It is possible to make various changes to each component or delete them. The present invention is not limited by the above description, but only by the scope of the appended claims.

According to the above shock absorber, it is possible to provide a shock absorber capable of greatly changing the damping force according to the frequency from the region where the piston speed is low.

11 Shock absorber 12 Cylinder 30 Piston 31 Upper chamber (first chamber, rod side chamber)
32 Lower chamber (second chamber, bottom chamber)
41 Piston rod 72 Mounting shaft (shaft)
91 Valve body (first valve body)
108 passage (first passage)
134 Valve body (second valve body)
200, 200A, 284A, 300 Frequency

sensitive part

201, 201A, 302

Case member

204, 311 Valve body (third valve body)
204A Valve body (4th valve body)
210, 210A, 303 Housing 236

Seal member

245, 246, 246A, 285A, 331, 332 Variable chamber (chamber)
251 passage (second passage)

Claims

A cylinder filled with a working fluid;
A piston that is slidably fitted in the cylinder and divides the cylinder into two chambers, a first chamber and a second chamber;
A piston rod connected to the piston and extending outside the cylinder;
A first passage and a second passage through which working fluid flows from one of the first chamber and the second chamber by the movement of the piston;
A first valve body provided in the first passage for generating a damping force,
In the second passage,
A second valve body that opens with a smaller pressure than the first valve body to generate a damping force;
When the working fluid flows from the first chamber to the second chamber, it is movable in the housing while defining the inside of the housing on the upstream side and the downstream side, and operates from the second chamber to the first chamber. A frequency sensitive portion having a third valve element that can be opened when fluid flows;
Is provided in series.
The first chamber is a rod side chamber, the second chamber is a bottom side chamber,
During the extension stroke, the third valve body moves within the housing while defining the upstream side and the downstream side to vary the damping force according to the frequency,
2. The shock absorber according to claim 1, wherein the third valve body is openable during a contraction stroke. 3.
In the second chamber side of the third valve body,
A frequency having a fourth valve body that is movable in the housing while defining the inside of the housing at the upstream side and the downstream side during the contraction stroke, and that can be opened during the extension stroke. The shock absorber according to claim 2, further comprising a sensitive portion.
The frequency sensitive part is
A cylindrical case member;
A shaft portion disposed in the case member;
An annular elastic seal member that is disposed in the case member through the shaft portion, is supported on the inner or outer peripheral side, and seals between the case member or the shaft portion on the non-support side. An annular third valve body provided and deflectable;
The shock absorber according to any one of claims 1 to 3, further comprising two chambers in the case member defined by the third valve body.