Shock absorber

Abstract

To provide a shock absorber which can control damping force precisely.SOLUTION: A shock absorber includes: a first damping force generation mechanism provided in a first passage; second passages 265, 275 provided separately from the first passage; an orifice part which is provided at the second passages 265, 275 and limits the flow rates of the second passages 265, 275; second damping force generation mechanism 268, 278 which are provided at the second passages 265, 275, have a first disc valve 167 and a second disc valve 161 in each of which one radial end is fixed and the other radial end is formed as a free end, and are operated prior to the first damping force generation mechanism by a moving speed of a piston relative to a cylinder to generate damping force; a first valve mechanism 254 which opens or closes a first communication hole 191 provided at the first disc valve 167 and allowing the upstream side and the downstream side to communicate with each other; and a second valve mechanism 244 which opens or closes a second communication hole 181 provided at the second disc valve 161 and allowing the upstream side and the downstream side to communicate with each other.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a shock absorber. [Background technology]

[0002] Some shock absorbers have a very low speed damping force generating valve that generates a damping force when the moving speed of the piston relative to the cylinder is very low and close to zero (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-173140 A Summary of the Invention [Problem to be solved by the invention]

[0004] In shock absorbers, there is a demand for precise control of damping force.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a shock absorber that allows for precise control of damping force. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention includes a cylinder in which a working fluid is sealed, a piston slidably provided within the cylinder and dividing the interior of the cylinder into two chambers, a piston rod connected to the piston and extending outside the cylinder, a first passage through which working fluid flows from the upstream chamber to the downstream chamber as the piston moves, a first damping force generating mechanism provided in the first passage and operated in response to a moving speed of the piston relative to the cylinder to generate a damping force, a second passage provided separately from the first passage, and a damping force generating mechanism provided in the second passage and configured to generate a damping force. The valve is configured to include an orifice portion which limits the flow rate of the second passage; a first disc valve and a second disc valve which are provided in the second passage, each having one radial end fixed and the other radial end formed as a free end, and which operates before the first damping force generating mechanism depending on the moving speed of the piston relative to the cylinder to generate a damping force; a first valve mechanism which opens and closes a first communication hole which is provided in the first disc valve and communicates between the upstream side and the downstream side, and a second valve mechanism which opens and closes a second communication hole which is provided in the second disc valve and communicates between the upstream side and the downstream side. Effect of the Invention

[0007] According to the present invention, it becomes possible to precisely control the damping force. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. [Diagram 2] 1 is a partial cross-sectional view showing a main portion of a shock absorber according to a first embodiment of the present invention. [Diagram 3] 2 is a partial cross-sectional view showing further details of the main part of the shock absorber according to the first embodiment of the present invention. FIG. [Figure 4] 1 is a hydraulic circuit diagram showing a main part of a shock absorber according to a first embodiment of the present invention. [Diagram 5] FIG. 5 is a partial cross-sectional view showing a main portion of a shock absorber according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] The first embodiment will be described with reference to FIGS.

[0010] The shock absorber 1 of the first embodiment shown in FIG. 1 is a shock absorber used in a suspension device of a railway vehicle or an automobile such as a two-wheeled vehicle or a four-wheeled vehicle. Specifically, the shock absorber 1 is a shock absorber used in a suspension device of a four-wheeled automobile. As shown in FIG. 1, the shock absorber 1 is a double-tube shock absorber equipped with a cylinder 4 having an inner tube 2 and an outer tube 3. The inner tube 2 is cylindrical. The outer tube 3 is a bottomed tube having a larger diameter than the inner tube 2. The outer tube 3 is provided radially outside the inner tube 2 and coaxially with the inner tube 2. A reservoir chamber 5 is formed between the outer tube 3 and the inner tube 2.

[0011] The outer cylinder 3 has a tubular portion 8 and a bottom portion 9. The tubular portion 8 is cylindrical. The bottom portion 9 closes one axial end of the tubular portion 8. The opposite side of the tubular portion 8 from the bottom portion 9 is an opening. A mounting eye 10 is fixed to the opposite side of the bottom portion 9 from the tubular portion 8 in the axial direction.

[0012] The shock absorber 1 includes a valve body 12 and a rod guide 13. The valve body 12 is annular, and is provided on the bottom 9 side of the inner cylinder 2 and the outer cylinder 3 in the axial direction. The rod guide 13 is annular, and is provided on the opposite side of the inner cylinder 2 and the outer cylinder 3 from the bottom 9 in the axial direction. The valve body 12 constitutes a base valve 15. The valve body 12 has a stepped outer periphery, and is placed on the bottom 9 with its large diameter portion positioned radially in the cylindrical portion 8. The rod guide 13 also has a stepped outer periphery, and its large diameter portion is positioned radially in the cylindrical portion 8 and fitted thereto.

[0013] One axial end of the inner cylinder 2 is fitted into the small diameter portion of the outer periphery of the valve body 12. One axial end of the inner cylinder 2 is engaged with the bottom 9 of the outer cylinder 3 via the valve body 12. The other axial end of the inner cylinder 2 is fitted into the small diameter portion of the outer periphery of the rod guide 13. The other axial end of the inner cylinder 2 is engaged with the tube portion 8 of the outer cylinder 3 via the rod guide 13. In this state, the inner cylinder 2 is positioned radially relative to the outer cylinder 3. Here, the space between the valve body 12 and the bottom 9 is in communication with the inner cylinder 2 and the outer cylinder 3. Therefore, the space between the valve body 12 and the bottom 9 constitutes a reservoir chamber 5, similar to the space between the inner cylinder 2 and the outer cylinder 3.

[0014] The shock absorber 1 is provided with a seal member 18. The seal member 18 is provided on the opposite side of the rod guide 13 from the bottom 9. This seal member 18 is also fitted to the inner periphery of the tubular portion 8, similar to the rod guide 13. An engagement portion 19 is formed on the end of the tubular portion 8 opposite the bottom 9. The engagement portion 19 is formed by plastically deforming the tubular portion 8 radially inward by crimping such as curling. The seal member 18 is sandwiched between the engagement portion 19 and the rod guide 13. The seal member 18 closes the opening of the outer cylinder 3, and is specifically an oil seal.

[0015] The shock absorber 1 includes a piston 21. The piston 21 is slidably provided in a cylinder 4. Specifically, the piston 21 is slidably provided in an inner tube 2 of the cylinder 4. The piston 21 divides the inner tube 2 into two chambers, a first chamber 22 and a second chamber 23. The first chamber 22 is provided between the piston 21 and the rod guide 13 in the inner tube 2. The second chamber 23 is provided between the piston 21 and the valve body 12 in the inner tube 2. The second chamber 23 is defined as a reservoir chamber 5 by the valve body 12. In the cylinder 4, an oil liquid L, which is a working fluid, is sealed in the first chamber 22 and the second chamber 23. In the cylinder 4, a gas G and an oil liquid L, which are working fluids, are sealed in the reservoir chamber 5. Thus, the shock absorber 1 is a hydraulic shock absorber that uses the oil liquid L, which is a working fluid.

[0016] The shock absorber 1 is provided with a piston rod 31 which is a rod-shaped shaft member. One axial end portion of the piston rod 31 is disposed inside the cylinder 4 and is connected and fixed to the piston 21. The other axial end portion of the piston rod 31 extends to the outside of the cylinder 4. The piston rod 31 is made of metal, and passes through the first chamber 22. The piston rod 31 does not pass through the second chamber 23. Therefore, the first chamber 22 is a rod side chamber through which the piston rod 31 passes. The second chamber 23 is a bottom side chamber on the bottom 9 side of the cylinder 4.

[0017] The piston 21 and the piston rod 31 move together. When the piston rod 31 increases its protrusion from the cylinder 4, in other words, during the extension stroke of the shock absorber 1 extending from the cylinder 4, the piston 21 moves toward the first chamber 22. When the piston rod 31 decreases its protrusion from the cylinder 4, in other words, during the compression stroke of the shock absorber 1 entering the cylinder 4, the piston 21 moves toward the second chamber 23.

[0018] Both the rod guide 13 and the seal member 18 are annular. The piston rod 31 is slidably inserted through the rod guide 13 and the seal member 18, and extends from the inside of the cylinder 4 to the outside. One axial end of the piston rod 31 is fixed to the piston 21 inside the cylinder 4. The other axial end of the piston rod 31 extends to the outside of the cylinder 4 via the rod guide 13 and the seal member 18.

[0019] The rod guide 13 supports the piston rod 31 relative to the cylinder 4 so as to be movable in the axial direction while restricting the piston rod 31 from moving in the radial direction. The outer periphery of the seal member 18 is in close contact with the outer tube 3 of the cylinder 4. The inner periphery of the seal member 18 is in sliding contact with the outer periphery of the piston rod 31 moving in the axial direction. In this way, the seal member 18 prevents the oil L and gas G in the cylinder 4 from leaking out to the outside.

[0020] The piston rod 31 has a main shaft portion 32, a mounting shaft portion 33, and a screw shaft portion 34. The mounting shaft portion 33 and the screw shaft portion 34 have a smaller diameter than the main shaft portion 32. The mounting shaft portion 33 extends from the main shaft portion 32, and the screw shaft portion 34 is provided on the opposite side of the mounting shaft portion 33 to the main shaft portion 32 in the axial direction. The main shaft portion 32 of the piston rod 31 is slidably fitted into the rod guide 13 and the seal member 18. The mounting shaft portion 33 and the screw shaft portion 34 of the piston rod 31 are disposed in the cylinder 4 and are connected to the piston 21, etc. The end of the main shaft portion 32 on the mounting shaft portion 33 side spreads in the direction perpendicular to the axis.

[0021] The mounting shaft portion 33 is cylindrical. As shown in FIG. 2, the mounting shaft portion 33 is formed with a base-side circumferential groove 41 having an annular shape recessed radially inward from its outer circumferential surface. The mounting shaft portion 33 is also formed with a tip-side circumferential groove 42 having an annular shape recessed radially inward from the outer circumferential surface of the mounting shaft portion 33, closer to the screw shaft portion 34 than the base-side circumferential groove 41 in the axial direction. The mounting shaft portion 33 is also formed with a pair of axial grooves 43 recessed radially inward from the outer circumferential surface of the mounting shaft portion 33 and extending in the axial direction of the mounting shaft portion 33, so as to communicate the base-side circumferential groove 41 and the tip-side circumferential groove 42.

[0022] The passage within the base end circumferential groove 41, the passages within the pair of axial grooves 43, and the passage within the tip end circumferential groove 42 constitute an axial passage 44 formed in the piston rod 31 extending in the axial direction of the piston rod 31.

[0023] The screw shaft portion 34 has a male thread 46 formed on the radially outer side.

[0024] The shock absorber 1 is supported by the vehicle body, for example, with the protruding portion of the piston rod 31 from the cylinder 4 as shown in Fig. 1 positioned at the top in the vertical direction. In this case, the shock absorber 1 is connected to the wheel side with the mounting eye 10 fixed to the bottom 9 of the cylinder 4 positioned at the bottom in the vertical direction. In the case where the shock absorber 1 is of a single-tube type, it is also possible to configure it in the opposite way, so that the cylinder 4 side is supported by the vehicle body and the piston rod 31 is connected to the wheel side.

[0025] As shown in FIG. 2, the piston 21 is composed of a metal piston body 61 supported by the piston rod 31, and an annular friction member 62 that is integrally attached to the outer circumferential surface of the piston body 61 and slides inside the inner cylinder 2.

[0026] The piston body 61 is formed with a plurality of passage holes 71 (only one is shown in FIG. 2 because it is a cross-section) and an annular passage groove 72 that connects the ends of these passage holes 71 opposite the first chamber 22. The piston body 61 is also formed with a plurality of passage holes 75 (only one is shown in FIG. 2 because it is a cross-section) and an annular passage groove 76 that connects the ends of these passage holes 75 on the first chamber 22 side. The plurality of passage holes 71 are formed in the circumferential direction of the piston body 61 with one passage hole 75 between each of them.

[0027] The passages in the multiple passage holes 71 and the passage in the passage groove 72 constitute a piston passage 81 that penetrates the piston 21 in the axial direction of the piston 21 and can communicate between the first chamber 22 and the second chamber 23. The passages in the multiple passage holes 75 and the passage in the passage groove 76 constitute a piston passage 82 that penetrates the piston 21 in the axial direction of the piston 21 and can communicate between the first chamber 22 and the second chamber 23.

[0028] The piston passage 81 is provided with a first damping force generating mechanism 85 which is a valve that opens and closes the piston passage 81 to generate a damping force. The first damping force generating mechanism 85 is disposed on the second chamber 23 side, which is one end side of the piston 21 in the axial direction, and is attached to the piston rod 31. By disposing the first damping force generating mechanism 85 on the second chamber 23 side, the oil L flowing out from the first chamber 22 flows toward the second chamber 23 in the piston passage 81 when the piston 21 moves toward the first chamber 22 side, that is, during the extension stroke. The first damping force generating mechanism 85 provided for the piston passage 81 serves as an extension-side damping force generating mechanism that generates a damping force by suppressing the flow of the oil L from the extension-side piston passage 81 to the second chamber 23.

[0029] The piston passage 82 is provided with a first damping force generating mechanism 86 which is a valve that opens and closes the piston passage 82 to generate a damping force. The first damping force generating mechanism 86 is disposed on the first chamber 22 side, which is the other end side of the piston 21 in the axial direction, and is attached to the piston rod 31. By disposing the first damping force generating mechanism 86 on the first chamber 22 side, the oil L flowing out from the second chamber 23 flows toward the first chamber 22 in the piston passage 82 when the piston 21 moves toward the second chamber 23 side, that is, during the compression stroke. The first damping force generating mechanism 86 provided for the piston passage 82 serves as a compression-side damping force generating mechanism that generates a damping force by suppressing the flow of the oil L from the compression-side piston passage 82 to the first chamber 22.

[0030] As a result of the above, the piston passage 81 and the piston passage 82 are connected so that the oil liquid L flows between the first chamber 22 and the second chamber 23 as the piston 21 moves. The oil liquid L passes through the piston passage 81 when the piston rod 31 and the piston 21 move toward the extension side, and the oil liquid L passes through the piston passage 82 when the piston rod 31 and the piston 21 move toward the contraction side.

[0031] The piston body 61 is composed of two members, a first piston body 91 and a second piston body 92. The first piston body 91 constitutes a portion of the piston body 61 on the second chamber 23 side in the axial direction, and the second piston body 92 constitutes a portion of the piston body 61 on the first chamber 22 side in the axial direction.

[0032] The first piston body 91 is in the shape of a disk with holes. A passage groove 102 is formed in an axial end face of the first piston body 91 on the second piston body 92 side, and extends inward from the piston passage 81 along the radial direction of the first piston body 91. The passage in the passage groove 102 communicates with the piston passage 81 and forms an orifice portion 103 that narrows the flow path more than the piston passage 81.

[0033] The above-mentioned passage groove 72 is formed at an end portion of the first piston body 91 on the second chamber 23 side in the axial direction. An annular valve seat portion 105 constituting a part of the first damping force generating mechanism 85 is formed at an end portion of the first piston body 91 on the second chamber 23 side in the axial direction radially outward from an opening of the passage groove 72 on the second chamber 23 side. In addition, an inner seat portion 106 is formed at an end portion of the piston main body 61 on the second chamber 23 side in the axial direction radially inward from an opening of the passage groove 72 on the second chamber 23 side.

[0034] The first piston body 91 is formed with an engagement protrusion 108 that protrudes outward along the axial direction of the first piston body 91 from an end face of the first piston body 91 on the second piston body 92 side in the axial direction. The engagement protrusion 108 is provided partially in the circumferential direction of the first piston body 91.

[0035] The second piston body 92 is in the shape of a perforated disk. The above-mentioned passage groove 76 is formed at the end of the second piston body 92 on the first chamber 22 side in the axial direction. An annular valve seat portion 115 constituting a part of the first damping force generating mechanism 86 is formed at the end of the second piston body 92 on the first chamber 22 side in the axial direction, radially outward from the opening of the passage groove 76 on the first chamber 22 side. In addition, an inner seat portion 116 is formed at the end of the piston main body 61 on the first chamber 22 side in the axial direction, radially inward from the opening of the passage groove 76 on the first chamber 22 side.

[0036] The second piston body 92 has an engagement recess 118 formed therein, which is recessed inward along the axial direction of the second piston body 92 from an end face of the second piston body 92 on the first piston body 91 side in the axial direction of the second piston body 92. The engagement recess 118 is provided partially in the circumferential direction of the second piston body 92.

[0037] The first piston body 91 and the second piston body 92 are connected by engaging the engagement protrusion 108 of the first piston body 91 with the engagement recess 118 of the second piston body 92. As a result, the first piston body 91 and the second piston body 92 are connected in a state in which they are positioned in the circumferential direction so as to form the piston passages 81 and 82. In this state, the friction member 62 is placed over the radially outer sides of the first piston body 91 and the second piston body 92. As a result, the first piston body 91 and the second piston body 92 are integrated to form the piston main body 61, and the first piston body 91, the second piston body 92, and the friction member 62 are integrated to form the piston 21.

[0038] In the first piston body 91, the opening of the compression-side piston passage 82 on the second chamber 23 side is disposed radially outward of the valve seat portion 105. In the second piston body 92, the opening of the extension-side piston passage 81 on the first chamber 22 side is disposed radially outward of the valve seat portion 115.

[0039] The piston 21 is disposed so that its orifice portion 103 overlaps with the base end side circumferential groove 41 of the mounting shaft portion 33 that is fitted inside, in the axial direction of the piston rod 31. This allows the orifice portion 103 to communicate with the axial passage 44 of the piston rod 31 without circumferential phase alignment of the piston 21 with respect to the piston rod 31.

[0040] The first damping force generating mechanism 86 on the compression side includes a valve seat portion 115 of the piston 21. The first damping force generating mechanism 86 is provided with, in this order from the piston 21 side in the axial direction, one disk 121, multiple disks 122, one disk 123, one disk 124, and one annular member 125. The disks 121 to 124 and the annular member 125 are all made of metal and have a circular flat plate shape with holes, and the mounting shaft portion 33 is fitted inside each of them.

[0041] The disk 121 has an outer diameter larger than the outer diameter of the inner seat portion 116 of the piston 21 and smaller than the inner diameter of the valve seat portion 115. The disk 121 is in contact with the inner seat portion 116 at all times.

[0042] Of the multiple discs 122, the disc 122 closest to the disc 121 in the axial direction has an outer diameter equal to the outer diameter of the valve seat portion 115 of the piston 21. Of the multiple discs 122, the disc 122 closest to the disc 121 in the axial direction is capable of being seated on the valve seat portion 115.

[0043] The disk 123 has an outer diameter smaller than the outer diameter of the plurality of disks 122 and slightly smaller than the outer diameter of the inner seat portion 116 of the piston 21 .

[0044] The disk 124 has an outer diameter larger than the outer diameter of the disk 123 .

[0045] The annular member 125 has an outer diameter smaller than that of the disks 124 and larger than that of the end of the main shaft portion 32 of the piston rod 31 on the mounting shaft portion 33 side in the axial direction. The annular member 125 is thicker and more rigid than the disks 121-124, and abuts against the end of the main shaft portion 32 on the mounting shaft portion 33 side in the axial direction.

[0046] A plurality of discs 122 constitute a compression-side valve member 131 that is capable of being seated on and removed from the valve seat portion 115. The valve member 131 is flexible, and when it deforms and leaves the valve seat portion 115, it puts the piston passage 82 in communication with the first chamber 22. At that time, the valve member 131 suppresses the flow of oil liquid L between it and the valve seat portion 115, generating a damping force. When the valve member 131 is seated on the valve seat portion 115, it blocks communication between the piston passage 82 and the first chamber 22. The annular member 125, together with the discs 124, abuts against the valve member 131 to suppress deformation of the valve member 131 in the opening direction beyond a specified level.

[0047] The piston passage 82 and a passage between the valve member 131 and the valve seat portion 115 that appears when the valve is opened constitute a first passage 132. The first passage 132 is provided in the piston 21. The first passage 132 is a compression-side passage through which the oil L flows from the second chamber 23, which is the upstream side in the cylinder 4, to the first chamber 22, which is the downstream side, as the piston 21 moves toward the second chamber 23. A compression-side first damping force generating mechanism 86 that generates a damping force includes the valve member 131 and the valve seat portion 115. The first damping force generating mechanism 86 is provided in the first passage 132. The first passage 132 is provided in the piston 21 including the valve seat portion 115, and the oil L passes through the first passage 132 when the piston rod 31 and the piston 21 move toward the compression side.

[0048] In the first passage 132, oil L flows from the second chamber 23 on the upstream side to the first chamber 22 on the downstream side due to the movement of the piston 21. The first damping force generating mechanism 86 is provided in the first passage 132, and is operated by the moving speed of the piston 21 relative to the cylinder 4, i.e., the valve member 131 is deflected, generating a damping force.

[0049] Here, in the compression-side first damping force generating mechanism 86, neither the valve seat portion 115 nor the valve member 131 abutting therewith is provided with a fixed orifice that connects the first chamber 22 and the second chamber 23 even when the valve seat portion 115 and the valve member 131 are in contact with each other. Therefore, the first passage 132 is not a passage that constantly connects the first chamber 22 and the second chamber 23.

[0050] The extension-side first damping force generating mechanism 85 includes a valve seat portion 105 of the piston 21. The first damping force generating mechanism 85 is provided with, in order from the piston 21 side in the axial direction, one disc 141, multiple discs 142, one disc 143, and multiple discs 144. All of the discs 141 to 144 are made of metal and have a circular flat plate shape with holes, and the mounting shaft portion 33 is fitted inside each of them.

[0051] The disk 141 has an outer diameter larger than the outer diameter of the inner seat portion 106 of the piston 21 and smaller than the inner diameter of the valve seat portion 105. The disk 141 is in contact with the inner seat portion 106 at all times.

[0052] Of the multiple discs 142, the disc 142 closest to disc 141 in the axial direction has an outer diameter equal to the outer diameter of valve seat portion 105 of piston 21. Of the multiple discs 142, the disc 142 closest to disc 141 in the axial direction is capable of being seated on valve seat portion 105.

[0053] The disk 143 has an outer diameter smaller than the outer diameter of any of the plurality of disks 142 and equal to the outer diameter of the inner seat portion 106 of the piston 21 .

[0054] The plurality of disks 144 have an outer diameter larger than the outer diameter of the disks 143 .

[0055] A plurality of discs 142 constitute an extension-side valve member 151 that is releasable from the valve seat portion 105. The valve member 151 is flexible, and when it is releasable from the valve seat portion 105, it connects the piston passage 81 to the second chamber 23. At that time, the valve member 151 suppresses the flow of oil liquid L between the valve seat portion 105 and generates a damping force. When the valve member 151 is seated on the valve seat portion 105, it blocks communication between the piston passage 81 and the second chamber 23.

[0056] The piston passage 81 and a passage between the valve member 151 and the valve seat portion 105 that appears when the valve is opened constitute a first passage 152. The first passage 152 is formed in the piston 21. The first passage 152 is an extension-side passage through which the oil L flows from the first chamber 22, which is the upstream side in the cylinder 4, to the second chamber 23, which is the downstream side, as the piston 21 moves toward the first chamber 22. The extension-side first damping force generating mechanism 85 that generates a damping force includes the valve member 151 and the valve seat portion 105. The first damping force generating mechanism 85 is provided in this first passage 152. The first passage 152 is provided in the piston 21 including the valve seat portion 105, and the oil L passes through the first passage 152 when the piston rod 31 and the piston 21 move toward the extension side.

[0057] In the first passage 152, the oil L flows from the first chamber 22 on the upstream side to the second chamber 23 on the downstream side due to the movement of the piston 21. The first damping force generating mechanism 85 is provided in the first passage 152, and is operated by the moving speed of the piston 21 relative to the cylinder 4, i.e., the valve member 151 is deflected, generating a damping force.

[0058] In the first damping force generating mechanism 85 on the extension side, a fixed orifice that communicates between the first chamber 22 and the second chamber 23 even when the valve seat portion 105 and the valve member 151 are in contact with each other is not formed in either the valve seat portion 105 or the valve member 151 that abuts thereon. Therefore, the first passage 152 is not a passage that constantly communicates between the first chamber 22 and the second chamber 23.

[0059] The orifice portion 103 provided in the piston 21 communicates with the first chamber 22 via a part of the piston passage 81 on the first chamber 22 side relative to the orifice portion 103. The orifice portion 103 is provided in parallel with the first passage 152.

[0060] On the axial side of disc 144 opposite disc 143, as shown in FIG. 3, the shock absorber 1 has, in order from the disc 144 side, one disc 160, one opening side disc valve 161 (second disc valve), one opening side opening / closing disc 162, one disc 163, one disc 164, one passage forming disc 165, one disc 166, one bottom side disc valve 167 (first disc valve), one bottom side opening / closing disc 168, one disc 169, one case member 170, one disc 171, and one annular member 172.

[0061] The disks 160, 163, 164, 166, 169, 171, the opening side disk valve 161, the opening side opening / closing disk 162, the passage forming disk 165, the bottom side disk valve 167, the bottom side opening / closing disk 168, the case member 170 and the annular member 172 each have the mounting shaft portion 33 of the piston rod 31 fitted into their respective insides.

[0062] 2 is disposed on the mounting shaft portion 33 of the piston rod 31 at a portion that protrudes beyond the annular member 172. A nut member 175 is screwed into the male thread 46 on the outer periphery of the threaded shaft portion 34. The nut member 175 abuts against the annular member 172.

[0063] The disks 160, 163, 164, 166, 169, 171, the opening side disk valve 161, the opening side opening / closing disk 162, the passage forming disk 165, the bottom side disk valve 167, the bottom side opening / closing disk 168, the case member 170, and the annular member 172, together with the piston 21, the disks 121 to 124, 141 to 144, and the annular member 125, are clamped to the main shaft portion 32 of the piston rod 31 and the nut member 175. As a result, at least the inner periphery side of each of the disks 160, 163, 164, 166, 169, 171, the opening side disk valve 161, the opening side opening / closing disk 162, the passage forming disk 165, the bottom side disk valve 167, the bottom side opening / closing disk 168, the case member 170, and the annular member 172 is fixed to the mounting shaft portion 33 of the piston rod 31.

[0064] The disks 160, 163, 164, 166, 169, 171, the opening side disk valve 161, the opening side opening / closing disk 162, the passage forming disk 165, the bottom side disk valve 167, the bottom side opening / closing disk 168, the case member 170 and the annular member 172 are all made of metal. The disks 160, 163, 164, 166, 169, 171, the opening side disk valve 161, the opening side opening / closing disk 162, the bottom side disk valve 167, the bottom side opening / closing disk 168 and the annular member 172 are all circular flat plates with holes and a constant thickness.

[0065] Disk 160 has an outer diameter that is smaller than the outer diameter of disk 144 .

[0066] The opening side disc valve 161 has an inner circumferential side, which is one radial end, fixed to the piston rod 31, and an outer circumferential side, which is the other radial end, formed as a free end. The opening side disc valve 161 is flexible. The opening side disc valve 161 has an outer diameter larger than the outer diameter of the disc 160. The opening side disc valve 161 has an opening side communication hole 181 (second communication hole) penetrating the opening side disc valve 161 in the axial direction, i.e., the thickness direction. The inner end of the opening side communication hole 181 in the radial direction of the opening side disc valve 161 is located outside the outer diameter part of the disc 160. Therefore, the disc 160 does not overlap with the opening side communication hole 181 of the opening side disc valve 161 in the radial direction.

[0067] The opening side opening / closing disk 162 has an inner circumferential side, which is one radial end, fixed to the piston rod 31, and an outer circumferential side, which is the other radial end, formed as a free end. The opening side opening / closing disk 162 is flexible. The opening side opening / closing disk 162 has an outer diameter smaller than the outer diameter of the opening side disk valve 161. The opening side opening / closing disk 162 has an outer diameter portion outside the outer end of the opening side communication hole 181 of the opening side disk valve 161 in the radial direction of the opening side disk valve 161. Also, the opening side opening / closing disk 162 has an inner diameter portion inside the inner end of the opening side communication hole 181 in the radial direction of the opening side disk valve 161. Therefore, the opening side opening / closing disk 162 overlaps with the entire opening side communication hole 181 of the opening side disk valve 161 in the radial direction. As a result, when the opening-side opening-closing disk 162 is in full contact with the opening-side disk valve 161 , it covers the entire opening-side communication hole 181 and closes it.

[0068] The disk 163 has an outer diameter smaller than that of the opening side opening / closing disk 162. The outer diameter portion of the disk 163 is located inside the inner end of the opening side communication hole 181 of the opening side disk valve 161 in the radial direction of the opening side disk valve 161. Therefore, the disk 163 does not overlap with the opening side communication hole 181 of the opening side disk valve 161 in the radial direction. The disk 163 and the disk 160 can be formed as a common component.

[0069] The outer diameter of the disk 164 is larger than the outer diameter of the disk 163 and smaller than the outer diameter of the opening side opening / closing disk 162. The outer diameter portion of the disk 164 is located between the outer end and inner end of the opening side communication hole 181 of the opening side disk valve 161 in the radial direction of the opening side disk valve 161.

[0070] The passage forming disk 165 has a base portion 185 and a pedestal portion 186 . The base plate portion 185 is in the shape of a circular flat plate having holes. The outer diameter of the base plate portion 185 is larger than the outer diameter of the disk 163 and smaller than the outer diameter of the disk 164. The outer diameter portion of the base plate portion 185 is located between the outer end and inner end of the opening side communication hole 181 of the opening side disk valve 161 in the radial direction of the opening side disk valve 161. The mounting shaft portion 33 of the piston rod 31 fits into the inner peripheral portion of the base plate portion 185.

[0071] The pedestal portion 186 is provided on one side of the base plate portion 185 in the axial direction, i.e., the thickness direction. The pedestal portion 186 is provided in the radial direction of the base plate portion 185 from the outer peripheral edge of the base plate portion 185 to a middle position slightly closer to the outer peripheral edge than the inner peripheral edge of the base plate portion 185. The pedestal portion 186 has a shape in which a central portion of a sector having an outer diameter equal to the outer diameter of the base plate portion 185 is cut out, and is provided on the base plate portion 185 with the central axis of the sector coinciding with the central axis of the base plate portion 185. The passage forming disk 165 is provided with a plurality of pedestal portions 186 of the same shape at equal intervals in the circumferential direction of the base plate portion 185. The plurality of pedestal portions 186 are radially spaced from the mounting shaft portion 33 of the piston rod 31.

[0072] In the passage forming disk 165, between adjacent pedestal portions 186 in the circumferential direction of the substrate portion 185, passage grooves 187 extend along the radial direction of the substrate portion 185 and penetrate between adjacent pedestal portions 186 in the radial direction of the substrate portion 185. In the passage forming disk 165, a plurality of passage grooves 187 of the same shape are provided at equal intervals in the circumferential direction of the substrate portion 185. The passage grooves 187 open on the opposite side to the substrate portion 185 in the axial direction of the substrate portion 185. The insides of the plurality of passage grooves 187 form passages 188.

[0073] A passage-forming disk 165 having such a configuration can be manufactured, for example, by forming the base portion 185 and the multiple pedestal portions 186 separately by press molding or the like, and then integrating them by bonding such as welding, or by machining them out of a single piece of material or forming them by forging or sintering.

[0074] The passage grooves 187 of the passage forming disc 165 are aligned with the tip side circumferential groove 42 of the piston rod 31 in the axial direction of the piston rod 31. Thus, the passages 188 in the passage grooves 187 of the passage forming disc 165 communicate with the axial passage 44.

[0075] The disk 166 has an outer diameter smaller than the outer diameter of the base portion 185 of the passage forming disk 165. The disk 166 and the disks 160, 163 can be formed as a common part.

[0076] The bottom side disc valve 167 has an inner circumferential side, which is one radial end, fixed to the piston rod 31, and an outer circumferential side, which is the other radial end, formed as a free end. The bottom side disc valve 167 is flexible. The bottom side disc valve 167 has an outer diameter larger than the outer diameter of the disc 166. The bottom side disc valve 167 has a bottom side communication hole 191 (first communication hole) penetrating the bottom side disc valve 167 in the axial direction, i.e., thickness direction. The inner end of the bottom side communication hole 191 in the radial direction of the bottom side disc valve 167 is located outside the outer diameter part of the disc 166. Therefore, the disc 166 does not overlap the bottom side communication hole 191 of the bottom side disc valve 167 in the radial direction. The outer diameter of the bottom side disc valve 167 is equal to the outer diameter of the opening side disc valve 161. The outside diameter of the bottom side disc valve 167 may be different from the outside diameter of the opening side disc valve 161 .

[0077] The bottom side opening / closing disc 168 has an inner circumferential side, which is one radial end, fixed to the piston rod 31, and an outer circumferential side, which is the other radial end, formed as a free end. The bottom side opening / closing disc 168 is flexible. The bottom side opening / closing disc 168 has an outer diameter smaller than the outer diameter of the bottom side disc valve 167. The outer diameter part of the bottom side opening / closing disc 168 is located outside the outer end of the bottom side communication hole 191 of the bottom side disc valve 167 in the radial direction of the bottom side disc valve 167. Also, the inner diameter part of the bottom side opening / closing disc 168 is located inside the inner end of the bottom side communication hole 191 in the radial direction of the bottom side disc valve 167. Therefore, the bottom side opening / closing disc 168 overlaps with the entire bottom side communication hole 191 of the bottom side disc valve 167 in the radial direction. As a result, when the bottom side opening / closing disk 168 is in full contact with the bottom side disk valve 167, it covers the entire bottom side communication hole 191 and closes the bottom side communication hole 191.

[0078] The disk 169 has an outer diameter smaller than that of the bottom-side opening-closing disk 168. The outer diameter portion of the disk 169 is located inside the inner end of the bottom-side communication hole 191 of the bottom-side disk valve 167 in the radial direction of the bottom-side disk valve 167. Therefore, the disk 169 does not overlap with the bottom-side communication hole 191 of the bottom-side disk valve 167 in the radial direction. The disk 169 can be a common part having the same outer diameter as the disks 160, 163, and 166.

[0079] The case member 170 is a one-piece molded product in the shape of a cylinder with a bottom. The case member 170 has a bottom 201 in the shape of a circular plate with a hole, and a cylindrical portion 202 extending from the outer periphery of the bottom 201 along the axial direction of the bottom 201 to the sides of the disks 160, 163, 164, 166, 169, the opening-side disk valve 161, the opening-side opening-closing disk 162, the passage-forming disk 165, the bottom-side disk valve 167, and the bottom-side opening-closing disk 168.

[0080] The outer diameter of the cylindrical portion 202, which is the outer diameter of the case member 170, is smaller than the inner diameter of the inner cylinder 2 shown in Fig. 2. The inner diameter of the cylindrical portion 202 is larger than the outer diameter of any of the disks 160, 163, 164, 166, 169, the opening side disk valve 161, the opening side opening and closing disk 162, the passage forming disk 165, the bottom side disk valve 167, and the bottom side opening and closing disk 168, as shown in Fig. 3. The disks 160, 163, 164, 166, 169, the opening side disk valve 161, the opening side opening and closing disk 162, the passage forming disk 165, the bottom side disk valve 167, and the bottom side opening and closing disk 168 are all disposed on the inner side of the case member 170 in the axial direction and the radial direction.

[0081] The bottom portion 201 of the case member 170 has an inner plate-shaped portion 211 , a middle plate-shaped portion 212 , and an outer plate-shaped portion 213 .

[0082] The inner plate-like portion 211 is a circular flat plate having a constant thickness. The mounting shaft portion 33 of the piston rod 31 fits into the inner periphery of the inner plate-like portion 211.

[0083] The intermediate plate-shaped portion 212 is tapered with a constant thickness, and expands from the outer peripheral edge of the inner plate-shaped portion 211 to the outside in the radial direction of the inner plate-shaped portion 211. The outer radial portion of the intermediate plate-shaped portion 212 is located on the opposite side to the disks 160, 163, 164, 166, 169, the opening-side disk valve 161, the opening-side opening-closing disk 162, the passage forming disk 165, the bottom-side disk valve 167, and the bottom-side opening-closing disk 168 in the axial direction from the inner plate-shaped portion 211 to the inner plate-shaped portion 211.

[0084] The outer plate-shaped portion 213 is an effectively circular flat plate of a constant thickness, and extends from the outer circumferential edge of the intermediate plate-shaped portion 212 outward in the radial direction of the intermediate plate-shaped portion 212. The outer plate-shaped portion 213 extends parallel to the inner plate-shaped portion 211.

[0085] The bottom 201 is formed with a passage hole 215 penetrating the bottom 201 in the axial direction, i.e., in the thickness direction. The passage hole 215 is formed across the intermediate plate-shaped portion 212 and the outer plate-shaped portion 213. The bottom 201 is formed with a plurality of passage holes 215 of the same shape at equal intervals in the circumferential direction of the bottom 201, with the positions of the passage holes 215 aligned in the radial direction of the bottom 201. The radius of the passage holes 215 to the outer end position in the radial direction of the bottom 201 is larger than the radius of the bottom open-close disk 168. The radius of the passage holes 215 to the inner end position in the radial direction of the bottom 201 is smaller than the radius of the bottom open-close disk 168.

[0086] The cylindrical portion 202 has a main body portion 221 , an opening side protrusion portion 222 , a bottom side protrusion portion 223 , and an expanded diameter portion 224 .

[0087] The main body portion 221 is cylindrical and extends from the outer peripheral edge portion of the bottom portion 201, i.e., the outer peripheral edge portion of the outer plate-shaped portion 213, along the axial direction of the bottom portion 201 toward the sides of the discs 160, 163, 164, 166, 169, the opening side disc valve 161, the opening side opening / closing disc 162, the passage forming disc 165, the bottom side disc valve 167 and the bottom side opening / closing disc 168.

[0088] The opening-side protrusion 222 is provided at a middle position in the axial direction of the main body portion 221, and protrudes inward from the main body portion 221 in the radial direction of the main body portion 221. The opening-side protrusion 222 is provided around the entire circumference of the main body portion 221, and is annular in shape.

[0089] The bottom-side protrusion 223 is provided at a position between the opening-side protrusion 222 and the outer plate-like portion 213 in the axial direction of the main body portion 221, and protrudes inward from the main body portion 221 in the radial direction of the main body portion 221. The bottom-side protrusion 223 is provided around the entire circumference of the main body portion 221 and is annular. The opening-side protrusion 222 and the bottom-side protrusion 223 have the same shape and therefore the same inner diameter. The opening-side protrusion 222 and the bottom-side protrusion 223 may have different shapes, and the inner diameter of the opening-side protrusion 222 may be different from the inner diameter of the bottom-side protrusion 223.

[0090] The expanded diameter portion 224 extends outward in the axial direction of the main body portion 221 from an end edge portion of the main body portion 221 opposite to the outer plate-shaped portion 213 in the axial direction. The expanded diameter portion 224 is tapered, and both its inner and outer diameters increase in the axial direction as it moves away from the main body portion 221.

[0091] The case member 170 is formed into the above-described shape by press working.

[0092] The opening-side disk valve 161, in an undeformed state (i.e., in an unoperated state), is aligned with the opening-side protrusion 222 of the case member 170 in the axial direction of the case member 170 and faces the opening-side protrusion 222 in the radial direction. When the opening-side disk valve 161 is in an undeformed state and aligned with the opening-side protrusion 222 of the case member 170 in the axial direction, the gap between the opening-side disk valve 161 and the opening-side protrusion 222 is narrowest.

[0093] In an undeformed state (i.e., in an unoperated state), the bottom disc valve 167 is aligned with the bottom protrusion 223 of the case member 170 in the axial direction of the case member 170 and faces the bottom protrusion 223 in the radial direction. When the bottom disc valve 167 is in an undeformed state and aligned with the bottom protrusion 223 of the case member 170 in the axial direction, the gap between the bottom disc valve 167 and the bottom protrusion 223 is narrowest.

[0094] When the opening side disc valve 161 and the bottom side disc valve 167 are both in a non-deformed state, the area surrounded by the case member 170, the opening side disc valve 161, the opening side opening / closing disc 162, disc 163, disc 164, the passage forming disc 165, disc 166, the bottom side disc valve 167, and the bottom side opening / closing disc 168 forms the case chamber 227.

[0095] The case chamber 227 communicates with the axial passage 44 of the piston rod 31 via passages 188 in the multiple passage grooves 187 of the passage forming disc 165. The case chamber 227, the passages 188 of the passage forming disc 165, and the axial passage 44 of the piston rod 31 form an intermediate chamber 228. The intermediate chamber 228 communicates with the orifice portion 103 shown in FIG. 2.

[0096] 3, when in a non-deformed state, the gap between the opening side disc valve 161 and the opening side protrusion 222 of the case member 170 is narrowest. This gap serves as the opening side communication passage 240 (communication passage) that communicates between the case chamber 227 and the second chamber 23. The opening side communication passage 240 is annular. The opening side communication passage 240 is formed between the opening side disc valve 161 in a non-deformed state and the case member 170 provided on the radial outer periphery of the opening side disc valve 161.

[0097] When the opening-side disc valve 161 is deformed, that is, in an operating state, and its outer periphery moves away from the opening-side protrusion 222 of the case member 170 in the axial direction, the gap with the opening-side protrusion 222 increases.

[0098] When the pressure on the case chamber 227 side becomes higher than the pressure on the second chamber 23 side by a predetermined value or more, the opening-side disc valve 161 elastically deforms so that the outer circumferential side moves away from the opening-side protrusion 222 of the case member 170 in the direction opposite to the bottom 201, and oil L flows from the case chamber 227 to the second chamber 23 through the gap with the opening-side protrusion 222. The deforming opening-side disc valve 161 and the opening-side protrusion 222 of the case member 170 at this time constitute a damping mechanism 241 that generates a damping force.

[0099] When the pressure on the second chamber 23 side becomes higher than the pressure on the case chamber 227 side by a predetermined value or more, the opening-side disc valve 161 elastically deforms so that the outer circumferential side approaches the bottom 201 from the opening-side protrusion 222 of the case member 170, and oil liquid L flows from the second chamber 23 to the case chamber 227 through the gap with the opening-side protrusion 222. The deforming opening-side disc valve 161 and the opening-side protrusion 222 of the case member 170 at this time constitute a damping mechanism part 242 that generates a damping force.

[0100] Therefore, the opening side disk valve 161 constitutes a damping mechanism 241 when it deforms away from the bottom 201 , and constitutes a damping mechanism 242 when it deforms toward the bottom 201 .

[0101] The opening-side communication passage 240 is a passage that communicates between the case chamber 227 and the second chamber 23, and is provided to allow the flow of oil liquid L separately from the flow of oil liquid L that occurs when the damping mechanism part 241 is in operation, i.e., when the valve is open, and communicates between the case chamber 227 on the upstream side of the damping mechanism part 241 and the second chamber 23 on the downstream side. That is, even when the opening-side disc valve 161 that constitutes the damping mechanism part 241 is in a non-operating state, i.e., a closed state, in which the opening-side disc valve 161 is closest to the opening-side protrusion part 222 that also constitutes the damping mechanism part 241, the shock absorber 1 communicates between the case chamber 227 and the second chamber 23 via the opening-side communication passage 240.

[0102] The opening-side communication passage 240 is a passage that communicates between the second chamber 23 and the case chamber 227, and is provided to allow the flow of oil liquid L separately from the flow of oil liquid L that occurs when the damping mechanism part 242 is in operation, i.e., when the valve is open, and communicates between the second chamber 23 on the upstream side of the damping mechanism part 242 and the case chamber 227 on the downstream side. That is, even when the opening-side disc valve 161 that constitutes the damping mechanism part 242 is in a non-operating state, i.e., a closed state, in which the opening-side disc valve 161 is closest to the opening-side protrusion part 222 that also constitutes the damping mechanism part 242, the shock absorber 1 communicates between the second chamber 23 and the case chamber 227 via the opening-side communication passage 240.

[0103] The opening-side communication hole 181 of the opening-side disk valve 161 and its surrounding portion, and the opening-side opening-closing disk 162 constitute an opening-side valve mechanism 244 (second valve mechanism). When the opening-side opening-closing disk 162 is in full contact with the opening-side disk valve 161, the opening-side valve mechanism 244 closes the opening-side communication hole 181 provided in the opening-side disk valve 161, blocking communication between the upstream second chamber 23 and the downstream case chamber 227. When the opening-side opening-closing disk 162 deforms toward the bottom 201 so as to move away from the opening-side disk valve 161, the opening-side valve mechanism 244 opens the opening-side communication hole 181 provided in the opening-side disk valve 161, connecting the upstream second chamber 23 and the downstream case chamber 227. In other words, the opening side valve mechanism 244 opens and closes the opening side communication hole 181 provided in the opening side disc valve 161, which communicates between the upstream second chamber 23 and the downstream case chamber 227.

[0104] In a state where the pressure in the second chamber 23 does not become higher than the pressure in the case chamber 227 by a predetermined value or more, including when the opening side disc valve 161 is deformed, the opening side opening / closing disc 162 comes into full contact with the opening side disc valve 161 to close the opening side communication hole 181. In this state, the opening side valve mechanism 244 does not allow the oil liquid L to flow between the second chamber 23 and the case chamber 227 through the opening side communication hole 181.

[0105] When the pressure in the second chamber 23 becomes higher than the pressure in the case chamber 227 by a predetermined value or more, the opening side valve mechanism 244 deforms so that the opening side opening / closing disc 162 moves away from the opening side disc valve 161, thereby opening the opening side communication hole 181. In this state, the opening side valve mechanism 244 allows the oil liquid L to flow from the second chamber 23 to the case chamber 227 via the opening side communication hole 181.

[0106] To operate as described above, the opening-side valve mechanism 244 is formed so that the opening area of ​​the opening-side communication hole 181 is larger than the pressure-receiving area (area of ​​the portion of the opening-side disc valve 161 excluding the opening-side communication hole 181 located radially outward from the disc 160) where the opening-side disc valve 161 receives pressure from the oil liquid L from the upstream second chamber 23. This condition is met when the outer diameter of the opening-side opening-closing disc 162 is equal to or smaller than the outer diameter of the opening-side disc valve 161. It is also possible to make the outer diameter of the opening-side opening-closing disc 162 larger than the outer diameter of the opening-side disc valve 161, and in that case, it is also possible to reduce the opening area of ​​the opening-side communication hole 181 by the area of ​​the opening-side opening-closing disc 162 radially outward from the opening-side disc valve 161.

[0107] That is, the opening-side valve mechanism 244 is formed so that the pressure-receiving area where the opening-side disc valve 161 receives pressure from the oil liquid L from the upstream second chamber 23 is larger than the pressure-receiving area where the opening-side disc valve 161 receives pressure from the oil liquid L from the case chamber 227. In other words, the opening-side valve mechanism 244 is formed so that the pressure-receiving area where the opening-side opening-closing disc 162 receives pressure from the oil liquid L from the upstream second chamber 23 is larger than the pressure-receiving area where the opening-side disc valve 161 receives pressure from the oil liquid L from the second chamber 23.

[0108] Here, when the pressure in the case chamber 227 becomes higher than the pressure in the second chamber 23 and the opening-side disc valve 161 deforms in the direction opposite to the bottom 201, the opening-side valve mechanism 244 maintains a state in which the opening-side opening-closing disc 162 deforms together with the opening-side disc valve 161 and is in full contact with the opening-side disc valve 161. In this state, the opening-side valve mechanism 244 does not allow the oil liquid L to flow from the case chamber 227 to the second chamber 23 through the opening-side communication hole 181.

[0109] The opening-side valve mechanism 244 is provided in a passage communicating the second chamber 23 and the case chamber 227 so as to allow the oil liquid L to flow therethrough separately from the oil liquid L generated when the damping mechanism part 242 is open, and communicates the second chamber 23 on the upstream side of the damping mechanism part 242 with the case chamber 227 on the downstream side. That is, when the opening-side disc valve 161 constituting the damping mechanism part 242 is in an open state separated from the opening-side protrusion part 222 also constituting the damping mechanism part 242, the opening-side valve mechanism 244 allows the oil liquid L to flow between the second chamber 23 and the case chamber 227 via a passage in the opening-side communication hole 181 provided in the opening-side disc valve 161 separately from the flow of the oil liquid L generated between the opening-side disc valve 161 and the opening-side protrusion part 222.

[0110] As described above, when the bottom side disc valve 167 is in a non-deformed state, the gap between the bottom side disc valve 167 and the bottom side protrusion 223 of the case member 170 is narrowest. This gap serves as a bottom side communication passage 250 (communication passage) that communicates between the case chamber 227 and the second chamber 23. The bottom side communication passage 250 is annular. The bottom side communication passage 250 is formed between the bottom side disc valve 167 in a non-deformed state and the case member 170 provided on the radial outer periphery of the bottom side disc valve 167.

[0111] When the bottom disc valve 167 is deformed, i.e., in an operating state, and its outer periphery moves away from the bottom protrusion 223 of the case member 170 in the axial direction, the gap between the bottom protrusion 223 and the bottom disc valve 167 increases.

[0112] When the pressure on the case chamber 227 side becomes higher than the pressure on the second chamber 23 side by a predetermined value or more, the bottom disc valve 167 elastically deforms so that the outer circumferential side moves away from the bottom protrusion 223 of the case member 170 toward the bottom 201 side, and oil L flows from the case chamber 227 through the gap with the bottom protrusion 223 and through the passage in the passage hole 215 of the bottom 201 to the second chamber 23. The deforming bottom disc valve 167 and the bottom protrusion 223 of the case member 170 at this time constitute a damping mechanism part 251.

[0113] When the pressure on the second chamber 23 side becomes higher than the pressure on the case chamber 227 side by a predetermined value or more, the bottom disc valve 167 elastically deforms so that the outer circumferential side moves away from the bottom protrusion 223 of the case member 170 to the opposite side from the bottom 201, and causes the oil liquid L that has passed through the passage in the passage hole 215 of the bottom 201 from the second chamber 23 to flow into the case chamber 227 through the gap with the bottom protrusion 223. The deforming bottom disc valve 167 and the bottom protrusion 223 of the case member 170 constitute the damping mechanism 252.

[0114] Therefore, when the bottom disc valve 167 deforms toward the bottom 201 , it constitutes a damping mechanism 251 , and when it deforms away from the bottom 201 , it constitutes a damping mechanism 252 .

[0115] The bottom side communication passage 250 is a passage that communicates between the case chamber 227 and the second chamber 23, and is provided to allow the flow of oil liquid L separately from the flow of oil liquid L generated when the damping mechanism part 251 is in operation, i.e., when the valve is open, and communicates between the case chamber 227 on the upstream side of the damping mechanism part 251 and the second chamber 23 on the downstream side. That is, even when the bottom side disc valve 167 constituting the damping mechanism part 251 is in a non-operating state, i.e., a closed state, in which the bottom side disc valve 167 is closest to the bottom side protrusion part 223 also constituting the damping mechanism part 251, the shock absorber 1 communicates between the case chamber 227 and the second chamber 23 via the bottom side communication passage 250.

[0116] The bottom side communication passage 250 is a passage that communicates between the second chamber 23 and the case chamber 227, and is provided to allow the flow of oil liquid L separately from the flow of oil liquid L generated when the damping mechanism part 252 is in operation, i.e., when the valve is open, and communicates between the second chamber 23 on the upstream side of the damping mechanism part 252 and the case chamber 227 on the downstream side. That is, even when the bottom side disc valve 167 constituting the damping mechanism part 252 is in a non-operating state, i.e., a closed state, in which the bottom side disc valve 167 is closest to the bottom side protrusion part 223 also constituting the damping mechanism part 252, the shock absorber 1 communicates between the second chamber 23 and the case chamber 227 via the bottom side communication passage 250.

[0117] The bottom side communication hole 191 of the bottom side disc valve 167 and its surrounding portion, and the bottom side opening / closing disc 168 constitute a bottom side valve mechanism 254 (first valve mechanism). When the bottom side opening / closing disc 168 is in full contact with the bottom side disc valve 167, the bottom side valve mechanism 254 closes the bottom side communication hole 191 provided in the bottom side disc valve 167, blocking communication between the upstream case chamber 227 and the downstream second chamber 23. When the bottom side opening / closing disc 168 deforms so as to move away from the bottom side disc valve 167, the bottom side valve mechanism 254 opens the bottom side communication hole 191 provided in the bottom side disc valve 167, connecting the upstream case chamber 227 and the downstream second chamber 23. In other words, the bottom side valve mechanism 254 opens and closes the bottom side communication hole 191 provided in the bottom side disc valve 167, which communicates between the upstream case chamber 227 and the downstream second chamber 23.

[0118] In a state where the pressure in the case chamber 227 does not become higher than the pressure in the second chamber 23 by a predetermined value or more, including when the bottom side disc valve 167 is deformed, the bottom side opening / closing disc 168 comes into full contact with the bottom side disc valve 167 to close the bottom side communication hole 191. In this state, the bottom side valve mechanism 254 does not allow the oil liquid L to flow between the case chamber 227 and the second chamber 23 through the bottom side communication hole 191.

[0119] When the pressure in the case chamber 227 becomes higher than the pressure in the second chamber 23 by a predetermined value or more, the bottom side valve mechanism 254 deforms so that the bottom side opening / closing disc 168 moves away from the bottom side disc valve 167, thereby opening the bottom side communication hole 191. In this state, the bottom side valve mechanism 254 allows the oil liquid L to flow from the case chamber 227 to the second chamber 23 through the bottom side communication hole 191.

[0120] In order to operate as described above, the bottom side valve mechanism 254 is formed so that the opening area of ​​the bottom side communication hole 191 is larger than the pressure receiving area (area of ​​the part of the bottom side disc valve 167 that is radially outward from the disc 166, excluding the bottom side communication hole 191) where the bottom side disc valve 167 receives pressure from the oil liquid L from the upstream case chamber 227. This condition is met when the outer diameter of the bottom side opening / closing disc 168 is equal to or smaller than the outer diameter of the bottom side disc valve 167. It is also possible to make the outer diameter of the bottom side opening / closing disc 168 larger than the outer diameter of the bottom side disc valve 167, in which case it is also possible to reduce the opening area of ​​the bottom side communication hole 191 by the area of ​​the bottom side opening / closing disc 168 radially outward from the bottom side disc valve 167.

[0121] That is, the bottom-side valve mechanism 254 is formed so that the pressure-receiving area where the bottom-side disc valve 167 receives pressure from the oil liquid L from the upstream case chamber 227 is larger than the pressure-receiving area where the bottom-side disc 168 receives pressure from the oil liquid L from the upstream case chamber 227. In other words, the bottom-side valve mechanism 254 is formed so that the pressure-receiving area where the bottom-side opening-closing disc 168 receives pressure from the oil liquid L from the upstream case chamber 227 is larger than the pressure-receiving area where the bottom-side disc valve 167 receives pressure from the oil liquid L from the case chamber 227.

[0122] Here, when the pressure in the second chamber 23 becomes higher than the pressure in the case chamber 227 and the bottom-side disc valve 167 deforms in the direction opposite to the bottom 201, the bottom-side valve mechanism 254 maintains a state in which the bottom-side opening-closing disc 168 deforms together with the bottom-side disc valve 167 and is in full contact with the bottom-side disc valve 167. In this state, the bottom-side valve mechanism 254 does not allow the oil liquid L to flow from the second chamber 23 to the case chamber 227 through the bottom-side communication hole 191.

[0123] The bottom side valve mechanism 254 is provided in a passage communicating between the case chamber 227 and the second chamber 23 so as to allow the oil liquid L to flow therethrough separately from the oil liquid L generated when the damping mechanism part 251 is open, thereby communicating the case chamber 227 on the upstream side of the damping mechanism part 251 with the second chamber 23 on the downstream side. That is, when the bottom side disc valve 167 constituting the damping mechanism part 251 is in an open state separated from the bottom side protrusion part 223 also constituting the damping mechanism part 251, the bottom side valve mechanism 254 allows the oil liquid L to flow between the case chamber 227 and the second chamber 23 via a passage in the bottom side communication hole 191 provided in the bottom side disc valve 167 separately from the oil liquid L generated between the bottom side disc valve 167 and the bottom side protrusion part 223.

[0124] In the shock absorber 1, a passage between the opening-side disc valve 161 that appears when the damping mechanism 241 is opened and the opening-side protrusion 222 constitutes a passage portion 261 through which the oil L flows in the direction shown by the arrow in Fig. 3. The passage portion 261 communicates with the case chamber 227 and the second chamber 23.

[0125] The passage between the bottom disc valve 167 that appears when the damping mechanism 251 is open and the bottom protrusion 223 constitutes a passage 262 through which the oil L flows in the direction shown by the arrow in Figure 3. The passage 262 communicates with the case chamber 227 and the second chamber 23.

[0126] The passage in the bottom communication hole 191 of the bottom disc valve 167 and the passage between the bottom disc valve 167 and the bottom opening / closing disc 168 that appears when the bottom valve mechanism 254 is opened constitute a passage portion 263. The passage portion 263 communicates with the case chamber 227 and the second chamber 23.

[0127] The passage portions 261, 262, 263 are all connected to the case chamber 227, and therefore are all connected to the orifice portion 103 provided in the piston 21 shown in FIG. 2 via the intermediate chamber 228 which includes the case chamber 227, the passage 188 provided in the passage forming disc 165, and the axial passage 44 provided in the piston rod 31.

[0128] A part of the piston passage 81 on the first chamber 22 side, the orifice portion 103, the intermediate chamber 228, and the passage portions 261, 262, and 263 constitute a second passage 265. The second passage 265 serves as an extension-side passage through which oil L flows from the first chamber 22, which is the upstream side in the cylinder 4, to the second chamber 23, which is the downstream side, as the piston 21 moves toward the first chamber 22 during the extension stroke. A part of the second extension-side passage 265 on the second chamber 23 side is provided separately in parallel with the first extension-side passage 152.

[0129] When constituting the damping mechanism 241, the opening-side disc valve 161 has an outer circumferential edge that moves close to or away from the opening-side protrusion 222 of the case member 170 to open and close a passage portion 261 of the second passage 265. When constituting the damping mechanism 241, the opening-side disc valve 161 and the opening-side protrusion 222 are provided in the passage portion 261 of the extension-side second passage 265, and open and close this passage portion 261 to suppress the flow of oil L from this passage portion 261 to the second chamber 23 side, thereby generating a damping force. The damping mechanism 241 constitutes an extension-side second damping force generating mechanism 268.

[0130] When constituting the damping mechanism 251, the bottom side disc valve 167 has an outer peripheral edge that moves close to or away from the bottom side protrusion 223 of the case member 170 to open and close the passage portion 262 of the second passage 265. The bottom side disc valve 167 and the bottom side protrusion 223 when constituting the damping mechanism 251 are provided in the passage portion 262 of the second passage 265 on the extension side, and open and close this passage portion 262 to suppress the flow of oil liquid L from this passage portion 262 to the second chamber 23 side, thereby generating a damping force. The damping mechanism 251 constitutes an extension side second damping force generating mechanism 268.

[0131] The bottom side opening / closing disc 168 and the bottom side disc valve 167 of the bottom side valve mechanism 254 are provided in the passage portion 263 of the second passage 265 on the extension side, and open and close this passage portion 263 to suppress the flow of oil L from this passage portion 263 to the second chamber 23 side, thereby generating a damping force. Therefore, the bottom side valve mechanism 254 is an extension side damping force generating mechanism formed to be able to open during the extension stroke when the piston rod 31 extends relative to the cylinder 4.

[0132] When at least one of the damping mechanism parts 241, 251 constituting the second damping force generating mechanism 268 is in an open state, in a second passage 265 consisting of a part of the piston passage 81, the orifice part 103, the intermediate chamber 228, and the passage parts 261, 262, the orifice part 103 in the piston 21 has a passage cross-sectional area narrowed down more than that on the upstream side. The orifice part 103 is provided in the second passage 265 and limits the flow rate of the oil liquid L in the second passage 265. The orifice part 103 is disposed upstream of the damping mechanism parts 241, 251 of the flow of the oil liquid L when the opening side disc valve 161 and the bottom side disc valve 167 of the damping mechanism parts 241, 251 constituting the second damping force generating mechanism 268 are opened and the oil liquid L flows in the second passage 265. In other words, the orifice portion 103 is positioned on the first chamber 22 side of the damping mechanism portions 241, 251 in the second passage 265 when at least one of the damping mechanism portions 241, 251 constituting the second damping force generating mechanism 268 is in an open state.

[0133] When the damping mechanism parts 241, 251 constituting the second damping force generating mechanism 268 are in a closed state, in the flow of the oil liquid L from the first chamber 22 to the second chamber 23 via a part of the piston passage 81, the orifice part 103, the intermediate chamber 228, the opening side communicating passage 240, and the bottom side communicating passage 250, the passage cross-sectional areas of the opening side communicating passage 240 and the bottom side communicating passage 250 are narrowed more than those of the upstream side. The opening side communicating passage 240 and the bottom side communicating passage 250 are disposed downstream of the orifice part 103 in the flow of the oil liquid L from the first chamber 22 to the second chamber 23 via a part of the piston passage 81, the orifice part 103, the intermediate chamber 228, the opening side communicating passage 240, and the bottom side communicating passage 250 when the opening side disc valve 161 of the damping mechanism part 241 and the bottom side disc valve 167 of the damping mechanism part 251 are closed. In other words, the opening side communicating passage 240 and the bottom side communicating passage 250 are arranged on the second chamber 23 side of the orifice portion 103 in the flow of oil liquid L from the first chamber 22 to the second chamber 23 via a part of the piston passage 81, the orifice portion 103, the intermediate chamber 228, the opening side communicating passage 240 and the bottom side communicating passage 250 when the damping mechanism portions 241, 251 that constitute the second damping force generating mechanism 268 are in a closed state.

[0134] When the damping mechanism 241 is configured, the opening-side disc valve 161 has its outer circumferential side separated from the opening-side protrusion 222, thereby communicating the first chamber 22 with the second chamber 23 via a second passage 265 including a part of the piston passage 81, the orifice 103, the intermediate chamber 228, and the passage 261. At this time, the opening-side disc valve 161 of the damping mechanism 241 suppresses the flow of oil L between it and the opening-side protrusion 222 to generate a damping force.

[0135] When the damping mechanism 251 is configured, the bottom disc valve 167 has its outer circumferential side separated from the bottom protrusion 223, thereby communicating the first chamber 22 with the second chamber 23 via a second passage 265 including a part of the piston passage 81, the orifice 103, the intermediate chamber 228, and the passage 262. At this time, the bottom disc valve 167 of the damping mechanism 251 suppresses the flow of oil L between it and the bottom protrusion 223, thereby generating a damping force.

[0136] In the bottom side valve mechanism 254, the passage in the bottom side communication hole 191, which is generated when the bottom side opening / closing disc 168 is separated from the bottom side disc valve 167, and the passage between the bottom side opening / closing disc 168 and the bottom side disc valve 167 constitute the passage portion 263 of the second passage 265. Therefore, the bottom side valve mechanism 254 opens and closes the passage portion 263 of the second passage 265.

[0137] The passage between the opening-side disc valve 161 and the opening-side protrusion 222 that appears when the damping mechanism 242 is open constitutes a passage 271 through which the oil L flows in the direction shown by the arrow in Fig. 3. The passage 271 communicates with the case chamber 227 and the second chamber 23.

[0138] The passage between the bottom disc valve 167 and the bottom protrusion 223 that appears when the damping mechanism 252 is open constitutes a passage 272 through which the oil L flows in the direction shown by the arrow in Figure 3. The passage 272 communicates with the case chamber 227 and the second chamber 23.

[0139] The passage in the opening side communication hole 181 of the opening side disc valve 161 and the passage between the opening side disc valve 161 and the opening side opening / closing disc 162 that appears when the opening side valve mechanism 244 is opened constitute a passage portion 273. The passage portion 273 communicates with the case chamber 227 and the second chamber 23.

[0140] The passage portions 271, 272, and 273 are all connected to the case chamber 227, and therefore are all connected to the orifice portion 103 provided in the piston 21 via an intermediate chamber 228 that includes the case chamber 227, a passage 188 provided in the passage forming disc 165, and an axial passage 44 provided in the piston rod 31.

[0141] The passage portions 271, 272, 273, the intermediate chamber 228, the orifice portion 103, and a part of the piston passage 81 on the first chamber 22 side constitute a second passage 275. The second passage 275 serves as a compression-side passage through which oil L flows from the second chamber 23, which is the upstream side in the cylinder 4, to the first chamber 22, which is the downstream side, as the piston 21 moves toward the second chamber 23 during the compression stroke. The second compression-side passage 275 is provided in parallel with and separate from the first compression-side passage 132.

[0142] When constituting the damping mechanism 242, the opening-side disc valve 161 has an outer circumferential edge that moves close to or away from the opening-side protrusion 222 of the case member 170 to open and close a passage portion 271 of the second passage 275. When constituting the damping mechanism 242, the opening-side disc valve 161 and the opening-side protrusion 222 are provided in the passage portion 271 of the second passage 275 on the compression side, and open and close this passage portion 271 to suppress the flow of oil L from this passage portion 271 to the first chamber 22 side, thereby generating a damping force. The damping mechanism 242 constitutes a compression-side second damping force generating mechanism 278.

[0143] When constituting the damping mechanism 252, the bottom side disc valve 167 has an outer peripheral edge that moves close to or away from the bottom side protrusion 223 of the case member 170 to open and close a passage portion 272 of the second passage 275. When constituting the damping mechanism 252, the bottom side disc valve 167 and the bottom side protrusion 223 are provided in the passage portion 272 of the second passage 275 on the compression side, and open and close this passage portion 272 to suppress the flow of oil L from this passage portion 272 to the first chamber 22 side, thereby generating a damping force. The damping mechanism 252 constitutes a second damping force generating mechanism 278 on the compression side.

[0144] The opening side opening / closing disc 162 and the opening side disc valve 161 of the opening side valve mechanism 244 are provided in a passage portion 273 of a second passage 275 on the compression side, and open and close this passage portion 273 to suppress the flow of oil L from this passage portion 273 to the first chamber 22 side, thereby generating a damping force. Therefore, the opening side valve mechanism 244 is a compression side damping force generating mechanism formed to be able to open during the compression stroke when the piston rod 31 enters the cylinder 4.

[0145] When at least one of the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 is in an open state, in a second passage 275 consisting of the passage parts 271, 272, the intermediate chamber 228, the orifice part 103 and a part of the piston passage 81, the orifice part 103 in the piston 21 has a passage cross-sectional area narrowed down more than that on the upstream side. The orifice part 103 is provided in the second passage 275 and limits the flow rate of the oil liquid L in the second passage 275. The orifice part 103 is disposed downstream of the damping mechanism parts 242, 252 of the flow of the oil liquid L when the opening side disc valve 161 and the bottom side disc valve 167 of the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are opened and the oil liquid L flows in the second passage 275. In other words, the orifice portion 103 is positioned on the first chamber 22 side of the damping mechanism portions 242, 252 in the second passage 275 when at least one of the damping mechanism portions 242, 252 that constitute the second damping force generating mechanism 278 is in an open state.

[0146] When the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are in a closed state, in the flow of the oil liquid L from the second chamber 23 to the first chamber 22 via the opening side communicating passage 240, the bottom side communicating passage 250, the intermediate chamber 228, the orifice part 103 and a part of the piston passage 81, the opening side communicating passage 240 and the bottom side communicating passage 250 have a passage cross-sectional area narrower than that of the upstream side. The opening side communicating passage 240 and the bottom side communicating passage 250 are disposed upstream of the orifice part 103 of the flow of the oil liquid L when the oil liquid L from the second chamber 23 is caused to flow to the first chamber 22 via the opening side communicating passage 240, the bottom side communicating passage 250, the intermediate chamber 228, the orifice part 103 and a part of the piston passage 81 with the opening side disc valve 161 of the damping mechanism part 242 and the bottom side disc valve 167 of the damping mechanism part 252 in a closed state. In other words, the opening side communicating passage 240 and the bottom side communicating passage 250 are arranged on the second chamber 23 side of the orifice portion 103 in the flow of oil liquid L through the opening side communicating passage 240, the bottom side communicating passage 250, the intermediate chamber 228, the orifice portion 103 and a part of the piston passage 81 when the damping mechanism parts 242, 252 that constitute the second damping force generating mechanism 278 are in a closed state.

[0147] When the damping mechanism 242 is configured, the opening-side disc valve 161 has its outer circumferential side separated from the opening-side protrusion 222, thereby communicating the second chamber 23 with the first chamber 22 through a second passage 275 including the passage 271, the intermediate chamber 228, the orifice 103, and a part of the piston passage 81. At this time, the opening-side disc valve 161 of the damping mechanism 242 suppresses the flow of oil L between it and the opening-side protrusion 222 to generate a damping force.

[0148] When the damping mechanism 252 is configured, the bottom disc valve 167 has its outer circumferential side separated from the bottom protrusion 223, thereby communicating the second chamber 23 with the first chamber 22 through a second passage 275 including the passage 272, the intermediate chamber 228, the orifice 103, and a part of the piston passage 81. At this time, the bottom disc valve 167 of the damping mechanism 252 suppresses the flow of oil L between it and the bottom protrusion 223, thereby generating a damping force.

[0149] In the opening-side valve mechanism 244, a passage in the opening-side communication hole 181, which is generated when the opening-side opening-closing disc 162 separates from the opening-side disc valve 161, and a passage between the opening-side opening-closing disc 162 and the opening-side disc valve 161 constitute a passage portion 273 of the second passage 275. Therefore, the opening-side valve mechanism 244 opens and closes the passage portion 273 of the second passage 275.

[0150] The disk 171 has an outer diameter smaller than the outer diameter of the inner plate-shaped portion 211 of the bottom 201 of the case member 170, and is in contact with the inner plate-shaped portion 211. The disk 171 has an outer diameter smaller than the diameter of the inscribed circle of the multiple passage holes 215 of the bottom 201 of the case member 170. The disk 171 can be a common part having the same outer diameter as the disks 160, 163, 166, and 169.

[0151] The outer diameter of the annular member 172 is smaller than the outer diameter of the disk 171 .

[0152] The opening side valve mechanism 244 is provided in the second passage 275 so as to allow the oil L to flow separately from the second damping force generating mechanism 278 consisting of the damping mechanism parts 242, 252, and operates when the second damping force generating mechanism 278 generates a predetermined damping force. The second valve mechanism 244 operates to open at a predetermined pressure during the compression stroke of the piston 21 relative to the cylinder 4, and operates to close during the extension stroke of the piston 21 relative to the cylinder 4.

[0153] The bottom side valve mechanism 254 is provided in the second passage 265 so as to allow the oil L to flow separately from the second damping force generating mechanism 268 consisting of the damping mechanism parts 241, 251, and operates when the second damping force generating mechanism 268 generates a predetermined damping force. The bottom side valve mechanism 254 operates to open at a predetermined pressure during the extension stroke of the piston 21 relative to the cylinder 4, and operates to close during the compression stroke of the piston 21 relative to the cylinder 4.

[0154] In the shock absorber 1, the damping force characteristics change depending on the shape of the case member 170 when the damping mechanism parts 241, 251 constituting the second damping force generating mechanism 268 and the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 operate.

[0155] That is, for example, by lengthening or shortening the length of the opening-side protrusion 222 in the axial direction of the case member 170 in the direction away from the bottom 201 with respect to the opening-side disc valve 161 in a non-deformed state, the damping force characteristics change when the damping mechanism 241 operates. Also, for example, by lengthening or shortening the length of the opening-side protrusion 222 in the axial direction of the case member 170 in the direction toward the bottom 201 with respect to the opening-side disc valve 161 in a non-deformed state, the damping force characteristics change when the damping mechanism 242 operates.

[0156] Also, for example, by lengthening or shortening the length of the bottom-side protrusion 223 in the axial direction of the case member 170 toward the bottom 201 with respect to the bottom-side disc valve 167 in a non-deformed state, the damping force characteristics change when the damping mechanism 251 operates. Also, for example, by lengthening or shortening the length of the bottom-side protrusion 223 in the axial direction of the case member 170 in the direction opposite to the bottom 201 with respect to the bottom-side disc valve 167 in a non-deformed state, the damping force characteristics change when the damping mechanism 252 operates.

[0157] A hydraulic circuit diagram of a configuration in which oil L flows between the first chamber 22 and the second chamber 23 provided in the piston rod 31 is as shown in FIG.

[0158] As shown in Fig. 4, the first extension-side damping force generating mechanism 85 is provided in the first extension-side passage 152 that allows the oil L to flow from the first chamber 22 to the second chamber 23. In addition, an orifice portion 103 is provided between the first chamber 228 and the middle chamber 22 of the second extension-side passage 265 that allows the oil L to flow from the first chamber 22 to the second chamber 23, separate from the first passage 152. In addition, the damping mechanism portion 241 and the damping mechanism portion 251 that constitute the second extension-side damping force generating mechanism 268, the extension-side bottom-side valve mechanism 254, and the opening-side communicating passage 240 and the bottom-side communicating passage 250 as orifices are provided in parallel between the middle chamber 228 and the second chamber 23 of the second passage 265.

[0159] A first compression-side damping force generating mechanism 86 is provided in a first compression passage 132 that allows oil L to flow from the second chamber 23 to the first chamber 22. In addition, an orifice portion 103 is provided between the first chamber 22 and the intermediate chamber 228 of a second compression passage 275 that allows oil L to flow from the second chamber 23 to the first chamber 22, separate from the first passage 132. In addition, a damping mechanism portion 242 and a damping mechanism portion 252 that constitute a second compression-side damping force generating mechanism 278, a compression-side opening-side valve mechanism 244, and an opening-side communicating passage 240 and a bottom-side communicating passage 250 as orifices are provided in parallel between the intermediate chamber 228 and the second chamber 23 of the second passage 275.

[0160] 1, the above-mentioned base valve 15 is provided between the bottom 9 of the outer cylinder 3 and the inner cylinder 2. This base valve 15 has the above-mentioned valve body 12 which separates the second chamber 23 and the reservoir chamber 5, a disk 302 provided on the lower side of the valve body 12, i.e., on the reservoir chamber 5 side, a disk 303 provided on the upper side of the valve body 12, i.e., on the second chamber 23 side, and a mounting pin 304 for mounting the disk 302 and the disk 303 to the valve body 12.

[0161] The valve body 12 has an annular shape, and a mounting pin 304 is inserted through the center in the radial direction. The valve body 12 is formed with a plurality of passage holes 305 through which the oil L can flow between the second chamber 23 and the reservoir chamber 5, and a plurality of passage holes 306 through which the oil L can flow between the second chamber 23 and the reservoir chamber 5, which are located radially outward of the valve body 12 from the passage holes 305. The disk 302 on the reservoir chamber 5 side allows the oil L to flow from the second chamber 23 to the reservoir chamber 5 via the passage hole (not shown) of the disk 303 and the passage hole 305 of the valve body 12, while suppressing the flow of the oil L from the reservoir chamber 5 to the second chamber 23 via the passage hole 305 and the passage hole (not shown) of the disk 303. The disk 303 allows the flow of the oil L from the reservoir chamber 5 to the second chamber 23 via the passage hole 306, while restricting the flow of the oil L from the second chamber 23 to the reservoir chamber 5 via the passage hole 306.

[0162] The disk 302, together with the valve body 12, constitutes a compression-side damping valve mechanism 307 that opens during the compression stroke of the shock absorber 1 to allow hydraulic fluid L to flow from the second chamber 23 to the reservoir chamber 5 and generate a damping force. The disk 303, together with the valve body 12, constitutes a suction valve mechanism 308 that opens during the extension stroke of the shock absorber 1 to allow hydraulic fluid L to flow from the reservoir chamber 5 into the second chamber 23. The suction valve mechanism 308 mainly functions to allow hydraulic fluid L to flow from the reservoir chamber 5 to the second chamber 23 without generating any damping force, so as to make up for a shortage of hydraulic fluid caused by the extension of the piston rod 31 from the cylinder 4.

[0163] Of the first damping force generating mechanism 85 provided in the first passage 152 on the extension side shown in FIG. 2 and the damping mechanism parts 241 and 251 constituting the second damping force generating mechanism 268 provided in the second passage 265 on the extension side shown in FIG. 3, the valve member 151 of the first damping force generating mechanism 85 has higher rigidity and higher valve opening pressure than the opening side disc valve 161 of the damping mechanism part 241 and the bottom side disc valve 167 of the damping mechanism part 251. Therefore, in the extension stroke, in a region where the moving speed of the piston (hereinafter referred to as piston speed) is lower than a predetermined value, the first damping force generating mechanism 85 is in a closed state and the damping mechanism parts 241 and 251 constituting the second damping force generating mechanism 268 are opened. In addition, in a normal speed region where the piston speed is equal to or higher than this predetermined value, both the first damping force generating mechanism 85 and the damping mechanism parts 241 and 251 constituting the second damping force generating mechanism 268 are opened.

[0164] In other words, the first damping force generating mechanism 85 is provided in the first passage 152, closes in a region where the piston speed is low, and opens in a region where the piston speed is higher than low. The damping mechanism parts 241 and 251 constituting the second damping force generating mechanism 268 are provided in the second passage 265, and open from a region where the piston speed is low. The opening side disc valve 161 of the damping mechanism part 241 and the bottom side disc valve 167 of the damping mechanism part 251 are extremely low speed valves that open in a region where the piston speed is extremely low to generate a damping force. The damping mechanism parts 241 and 251 constituting the second damping force generating mechanism 268 are provided in the second passage 265, and operate before the first damping force generating mechanism 85 when the moving speed of the piston 21 relative to the cylinder 4 is low to generate a damping force.

[0165] During the extension stroke, the piston 21 moves toward the first chamber 22, so that the pressure in the first chamber 22 increases and the pressure in the second chamber 23 decreases. During the extension stroke when the piston speed is less than a first predetermined value, the first damping force generating mechanism 85 provided in the first passage 152 and the damping mechanism parts 241 and 251 constituting the second damping force generating mechanism 268 provided in the second passage 265 do not open. For this reason, the oil L from the first chamber 22 flows through a part of the piston passage 81 of the piston 21 and the orifice part 103, the axial passage 44 of the piston rod 31, the passage 188 of the passage forming disc 165, and the case chamber 227, and is throttled by the opening side communicating passage 240 and the bottom side communicating passage 250 before flowing into the second chamber 23. Therefore, during the extension stroke when the piston speed is less than the first predetermined value, a damping force with orifice characteristics (wherein the damping force is approximately proportional to the square of the piston speed) is obtained, and the damping force rises rapidly.

[0166] In a region where the piston speed is equal to or higher than a first predetermined value where the damping mechanism parts 241, 251 constituting the second damping force generating mechanism 268 open, and in a very low speed region where the piston speed is higher than a second predetermined value and lower than the first predetermined value, the first damping force generating mechanism 85 is closed, and the damping mechanism parts 241, 251 constituting the second damping force generating mechanism 268 open. That is, the opening side disc valve 161 of the damping mechanism part 241 deforms together with the opening side opening / closing disc 162 toward the opposite side to the bottom part 201 and moves away from the opening side protrusion part 222, and the bottom side disc valve 167 of the damping mechanism part 251 deforms together with the bottom side opening / closing disc 168 toward the bottom part 201 and moves away from the bottom side protrusion part 223, thereby communicating the first chamber 22 with the second chamber 23 through the second passage 265 including the passage part 261 and the passage part 262. Therefore, the oil liquid L in the first chamber 22 flows into the second chamber 23 through a part of the piston passage 81 of the piston 21, the orifice portion 103, the axial passage 44 of the piston rod 31, the passage 188 of the passage forming disc 165, the case chamber 227, the passage portion 261, and the passage portion 262. As a result, even in an extremely low speed region where the piston speed is slower than the second predetermined value, a damping force with valve characteristics (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained.

[0167] In addition, during the extension stroke, in the region where the piston speed is equal to or greater than a second predetermined value and in the normal speed region which is faster than the second predetermined value and slower than a third predetermined value, the first damping force generating mechanism 85 opens while the damping mechanism sections 241, 251 that constitute the second damping force generating mechanism 268 remain open. In other words, the opening side disc valve 161 of the damping mechanism part 241 moves away from the opening side protrusion 222, and the bottom side disc valve 167 of the damping mechanism part 251 moves away from the bottom side protrusion 223, causing the oil liquid L to flow from the first chamber 22 to the second chamber 23 through the second passage 265. At this time, the flow of the oil liquid L is narrowed by the orifice part 103, which is located upstream of the damping mechanism parts 241, 251 in the second passage 265, so that the pressure applied to the valve member 151 of the first damping force generating mechanism 85 increases and the pressure difference increases, causing the valve member 151 to move away from the valve seat part 105, causing the oil liquid L to flow from the first chamber 22 to the second chamber 23 through the first passage 152. Therefore, the oil L in the first chamber 22 flows into the second chamber 23 via the first passage 152 consisting of the piston passage 81 of the piston 21 and the passage between the valve member 151 in the open state and the valve seat portion 105, in addition to flowing through the second passage 265 when the damping mechanism portions 241, 251 are in an open state. As a result, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) can be obtained even in a normal speed region where the piston speed is equal to or higher than the second predetermined value and is slower than the third predetermined value.

[0168] The rate of increase in the extension damping force with respect to an increase in the piston speed in the normal speed region is lower than the rate of increase in the extension damping force with respect to an increase in the piston speed in the extremely low speed region. In other words, the slope of the rate of increase in the extension damping force with respect to an increase in the piston speed in the normal speed region can be made gentler than in the extremely low speed region.

[0169] Here, during the extension stroke, when the piston speed becomes equal to or greater than a third predetermined value and the damping mechanism sections 241, 251 that constitute the second damping force generating mechanism 268 generate a predetermined damping force, the bottom valve mechanism 254 provided in the second passage 265 opens while the damping mechanism sections 241, 251 and the first damping force generating mechanism 85 remain in an open state. In other words, the opening side disc valve 161 of the damping mechanism part 241 moves away from the opening side protrusion 222, the bottom side disc valve 167 of the damping mechanism part 251 moves away from the bottom side protrusion 223 to allow oil liquid L to flow from the first chamber 22 to the second chamber 23 through the second passage 265, and the valve member 151 of the first damping force generating mechanism 85 moves away from the valve seat portion 105 to allow oil liquid L to flow from the first chamber 22 to the second chamber 23 through the first passage 152, and the bottom side valve mechanism 254 provided in the second passage 265 opens to allow oil liquid L to flow from the first chamber 22 to the second chamber 23 through the passage within the bottom side communicating hole 191 of the bottom side disc valve 167. That is, the bottom side opening / closing disc 168 moves away from the bottom side disc valve 167 to open the bottom side communication hole 191 of the bottom side disc valve 167, and a passage portion 263 is provided in the second passage 265 via the bottom side communication hole 191. As a result, the oil L flowing from the first chamber 22 through the second passage 265 to the second chamber 23 flows into the second chamber 23 through the second passage 265 in a state including the passage portion 263 passing through the inside of the bottom side communication hole 191 of the bottom side disc valve 167.

[0170] When the bottom side communication hole 191 opens, the pressure difference between the case chamber 227 side and the second chamber 23 side of the bottom side disc valve 167 decreases, and the outer peripheral edge returns from the elastically deformed state to align with the bottom side protrusion 223 of the case member 170 in the axial direction. In this way, by suppressing the pressure difference between the case chamber 227 side and the second chamber 23 side of the bottom side disc valve 167, excessive deformation of the bottom side disc valve 167 is suppressed.

[0171] Of the first damping force generating mechanism 86 provided in the first compression passage 132 shown in Fig. 2 and the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 provided in the second compression passage 275 shown in Fig. 3, the valve member 131 of the first damping force generating mechanism 86 has higher rigidity and higher valve opening pressure than the opening side disc valve 161 of the damping mechanism part 242 and the bottom side disc valve 167 of the damping mechanism part 252. Therefore, during the compression stroke, in a region where the piston speed is lower than a predetermined value, the first damping force generating mechanism 86 is in a closed state and the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are open, and in a normal speed region where the piston speed is equal to or higher than this predetermined value, both the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 and the first damping force generating mechanism 86 are open.

[0172] In other words, the first damping force generating mechanism 86 is provided in the first passage 132, closes in a region where the piston speed is low, and opens in a region where the piston speed is higher than low. The damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are provided in the second passage 275, and open from a region where the piston speed is low. The opening side disc valve 161 and the bottom side disc valve 167 of the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are extremely low speed valves that open in a region where the piston speed is extremely low to generate a damping force. The damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are provided in the second passage 275, and operate before the first damping force generating mechanism 86 when the moving speed of the piston 21 relative to the cylinder 4 is low to generate a damping force.

[0173] During the compression stroke, the piston 21 moves toward the second chamber 23, so that the pressure in the second chamber 23 increases and the pressure in the first chamber 22 decreases. During the compression stroke when the piston speed is less than the fourth predetermined value, the first damping force generating mechanism 86 provided in the first passage 132 and the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 provided in the second passage 275 do not open. For this reason, the oil L from the second chamber 23 flows into the first chamber 22 through the opening side communicating passage 240, the bottom side communicating passage 250, the case chamber 227, the passage 188 of the passage forming disc 165, the axial passage 44 of the piston rod 31, the orifice part 103 of the piston 21 and a part of the piston passage 81, and is throttled by the opening side communicating passage 240 and the bottom side communicating passage 250. Therefore, during the compression stroke when the piston speed is less than the fourth predetermined value, a damping force with orifice characteristics (wherein the damping force is approximately proportional to the square of the piston speed) is obtained, and the damping force rises rapidly.

[0174] In a region where the piston speed is equal to or higher than a fourth predetermined value at which the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are opened, and in a region where the piston speed is lower than a fifth predetermined value that is higher than the fourth predetermined value, the first damping force generating mechanism 86 is closed, and the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 are opened. That is, the opening side disc valve 161 deforms toward the bottom 201 side together with the opening side opening and closing disc 162, and moves away from the opening side protrusion part 222, and the bottom side disc valve 167 deforms toward the opposite side to the bottom 201 together with the bottom side opening and closing disc 168, and moves away from the bottom side protrusion part 223, thereby communicating the second chamber 23 and the first chamber 22 through the second passage 275 including the passage parts 271, 272. Thus, the oil L in the second chamber 23 flows into the first chamber 22 through the second passage 275. As a result, even in an extremely low speed region where the piston speed is slower than the fifth predetermined value, a damping force with a valve characteristic (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained.

[0175] In addition, during the compression stroke, in a region where the piston speed is equal to or higher than the fifth predetermined value and is lower than a sixth predetermined value, the first damping force generating mechanism 86 opens while the damping mechanism parts 242, 252 constituting the second damping force generating mechanism 278 remain open. That is, the opening side disc valve 161 moves away from the opening side protrusion 222, and the bottom side disc valve 167 moves away from the bottom side protrusion 223, and the oil L flows from the second chamber 23 to the first chamber 22 through the second passage 275 including the passage parts 271, 272. At this time, since the flow rate of the oil L is restricted by the orifice part 103 in the second passage 275, the differential pressure generated in the valve member 131 of the first damping force generating mechanism 86 becomes large, and the valve member 131 moves away from the valve seat part 115, and the oil L flows from the second chamber 23 to the first chamber 22 through the first passage 132. Therefore, the oil L in the second chamber 23 flows into the first chamber 22 via the first passage 132 consisting of the piston passage 82 of the piston 21 and the passage between the open valve member 131 and the valve seat portion 115, in addition to flowing through the second passage 275 when the damping mechanism portions 242, 252 constituting the second damping force generating mechanism 278 are in an open state. As a result, even in a normal speed region where the piston speed is equal to or greater than a fifth predetermined value and less than a sixth predetermined value, a damping force with valve characteristics (wherein the damping force is approximately proportional to the piston speed) can be obtained.

[0176] The rate of increase in the compression damping force with respect to an increase in the piston speed in the normal speed region is lower than the rate of increase in the compression damping force with respect to an increase in the piston speed in the extremely low speed region. In other words, the slope of the rate of increase in the compression damping force with respect to an increase in the piston speed in the normal speed region can be made gentler than in the extremely low speed region.

[0177] Here, during the compression stroke, when the piston speed reaches or exceeds a sixth predetermined value and the damping mechanism parts 242, 252 that constitute the second damping force generating mechanism 278 generate a predetermined damping force, the opening side valve mechanism 244 provided in the second passage 275 opens while the damping mechanism parts 242, 252 that constitute the second damping force generating mechanism 278 and the first damping force generating mechanism 86 remain in an open state. In other words, the opening side disc valve 161 of the damping mechanism part 242 moves away from the opening side protrusion 222, the bottom side disc valve 167 of the damping mechanism part 252 moves away from the bottom side protrusion 223 to allow the oil liquid L to flow from the first chamber 22 to the second chamber 23 through the second passage 275, and the valve member 131 of the first damping force generating mechanism 86 moves away from the valve seat portion 115 to allow the oil liquid L to flow from the second chamber 23 to the first chamber 22 through the first passage 132, and the opening side valve mechanism 244 provided in the second passage 275 opens to allow the oil liquid L to flow from the second chamber 23 to the first chamber 22 through the passage within the opening side communicating hole 181 of the opening side disc valve 161. That is, the opening side opening / closing disc 162 moves away from the opening side disc valve 161 to open the opening side communication hole 181 of the opening side disc valve 161, and a passage portion 273 that passes through the opening side communication hole 181 is provided in the second passage 275. As a result, the oil L that flows from the second chamber 23 through the second passage 275 to the first chamber 22 flows into the first chamber 22 through the second passage 275 in a state including the passage portion 273 that passes through the opening side communication hole 181 of the opening side disc valve 161.

[0178] When the opening-side communication hole 181 opens, the pressure difference between the second chamber 23 side and the case chamber 227 side of the opening-side disc valve 161 decreases, and the outer circumferential edge returns from the elastically deformed state to align with the opening-side protrusion 222 of the case member 170 in the axial direction. In this way, by reducing the pressure difference between the second chamber 23 side and the case chamber 227 side of the opening-side disc valve 161, excessive deformation of the opening-side disc valve 161 can be suppressed.

[0179] The above-mentioned Patent Document 1 discloses a shock absorber having a very low speed damping force generating valve that generates a damping force when the moving speed of the piston relative to the cylinder is very low speed close to 0. However, in the shock absorber, there is a demand for precise control of the damping force.

[0180] The shock absorber 1 of the first embodiment has a first damping force generating mechanism 85 that operates according to the moving speed of the piston 21 relative to the cylinder 4 to generate a damping force in a first passage 152 through which the oil L flows from the first chamber 22 on the upstream side to the second chamber 23 on the downstream side due to the movement of the piston 21. The shock absorber 1 also has damping mechanism parts 241, 251 in a second passage 265 provided separately from the first passage 152, the damping mechanism parts 241, 251 having an orifice part 103 that limits the flow rate of the second passage 265, an opening side disc valve 161 and a bottom side disc valve 167, both of which have one radial end fixed and the other radial end formed as a free end, and which operate before the first damping force generating mechanism 85 according to the moving speed of the piston 21 relative to the cylinder 4 to generate a damping force.

[0181] The shock absorber 1 also has a first damping force generating mechanism 86 which operates in accordance with the moving speed of the piston 21 relative to the cylinder 4 and generates a damping force in a first passage 132 through which the oil L flows from the second chamber 23 on the upstream side to the first chamber 22 on the downstream side due to the movement of the piston 21. The shock absorber 1 also has a second damping force generating mechanism 278 which operates in accordance with the moving speed of the piston 21 relative to the cylinder 4 and which has an orifice portion 103 which limits the flow rate of the second passage 275 in a second passage 275 provided separately from the first passage 132, an opening side disc valve 161 and a bottom side disc valve 167, both of which have one radial end fixed and the other radial end formed as a free end, and which operates before the first damping force generating mechanism 86 in accordance with the moving speed of the piston 21 relative to the cylinder 4 and which generates a damping force.

[0182] Furthermore, the shock absorber 1 includes a bottom valve mechanism 254 that opens and closes a bottom communication hole 191 that is provided in the bottom disc valve 167 and communicates between the upstream side and the downstream side.

[0183] Furthermore, the shock absorber 1 includes an opening-side valve mechanism 244 that opens and closes an opening-side communication hole 181 that is provided in the opening-side disc valve 161 and communicates between the upstream side and the downstream side.

[0184] As described above, the shock absorber 1 has the opening side disc valve 161, the bottom side disc valve 167, the bottom side valve mechanism 254 provided in the bottom side disc valve 167, and the opening side valve mechanism 244 provided in the opening side disc valve 161, making it possible to control the damping force in detail.

[0185] In the shock absorber 1 of the first embodiment, the bottom side valve mechanism 254 is formed so as to be able to open during the extension stroke in which the piston rod 31 extends relative to the cylinder 4, and the opening side valve mechanism 244 is formed so as to be able to open during the compression stroke in which the piston rod 31 advances relative to the cylinder 4. Therefore, in the shock absorber 1, the damping force can be set respectively in the extension stroke and the compression stroke, and therefore the degree of freedom in tuning the damping force characteristics in the extension stroke and the compression stroke can be improved.

[0186] In the shock absorber 1 of the first embodiment, the bottom side communication hole 191 is formed to have an area larger than the pressure receiving area where the bottom side disc valve 167 receives pressure from the upstream side by the oil liquid L as the working fluid, and the opening side communication hole 181 is formed to have an area larger than the pressure receiving area where the opening side disc valve 161 receives pressure from the upstream side by the oil liquid L. Therefore, in the shock absorber 1, the member that opens and closes the bottom side communication hole 191 can be easily opened and closed, and the member that opens and closes the opening side communication hole 181 can be easily opened and closed. In addition, in the shock absorber 1, when the bottom side communication hole 191 is opened, the differential pressure of the bottom side disc valve 167 is reduced, and excessive deformation of the bottom side disc valve 167 can be suppressed, and when the opening side communication hole 181 is opened, the differential pressure of the opening side disc valve 161 is reduced, and excessive deformation of the opening side disc valve 161 can be suppressed.

[0187] In the shock absorber 1 of the first embodiment, the bottom-side valve mechanism 254 is formed so that the pressure-receiving area that receives pressure from the oil liquid L, which is the working fluid from the upstream side, is larger than the pressure-receiving area of ​​the bottom-side disc valve 167 that receives pressure from the oil liquid L from the upstream side, and the opening-side valve mechanism 244 is formed so that the pressure-receiving area that receives pressure from the oil liquid L from the upstream side is larger than the pressure-receiving area of ​​the opening-side disc valve 161 that receives pressure from the oil liquid L from the upstream side. Therefore, the shock absorber 1 can easily open and close the bottom-side valve mechanism 254 and can easily open and close the opening-side valve mechanism 244. In addition, in the shock absorber 1, when the bottom-side communication hole 191 is opened, the differential pressure of the bottom-side disc valve 167 is reduced, and excessive deformation of the bottom-side disc valve 167 can be suppressed, and when the opening-side communication hole 181 is opened, the differential pressure of the opening-side disc valve 161 is reduced, and excessive deformation of the opening-side disc valve 161 can be suppressed.

[0188] The shock absorber 1 of the first embodiment has an opening-side communication passage 240 that is provided separately from the damping mechanism parts 241 and 242 to allow the oil liquid L, which is a working fluid, to flow therethrough, and that communicates the upstream side and downstream side of the damping mechanism parts 241 and 242, and the opening-side communication passage 240 is formed between the opening-side communication passage 240 and a case member 170 that is provided on the radial outer periphery of the opening-side disc valve 161. The shock absorber 1 also has a bottom-side communication passage 250 that is provided separately from the damping mechanism parts 251 and 252 to allow the oil liquid L, which is a working fluid, to flow therethrough, and that communicates the upstream side and downstream side of the damping mechanism parts 251 and 252, and the bottom-side communication passage 250 is formed between the bottom-side disc valve 167 and a case member 170 that is provided on the radial outer periphery of the bottom-side disc valve 167. Thus, the shock absorber 1 can easily adjust the valve opening amount for each of the damping mechanism parts 241, 242, 251, and 252, and can increase the degree of freedom in tuning.

[0189] In the shock absorber 1 of the first embodiment, the case member 170 is formed by press working, so that the manufacturing cost can be suppressed.

[0190] [Second embodiment] Next, the second embodiment will be described with a focus on the differences from the first embodiment, mainly based on Fig. 5. Note that the same names and symbols are used for the parts common to the first embodiment.

[0191] The shock absorber 1A of the second embodiment has a case member 170A which is partially different from the case member 170 of the first embodiment instead of the case member 170.

[0192] The case member 170A is a one-piece molded product in the shape of a cylinder with a bottom. The case member 170A has a bottom 201A in the shape of a perforated disk, and a cylindrical portion 202A extending from the outer peripheral edge of the bottom 201A along the axial direction of the bottom 201A toward the disks 160, 163, 164, 166, 169, the opening-side disk valve 161, the opening-side opening-closing disk 162, the passage-forming disk 165, the bottom-side disk valve 167, and the bottom-side opening-closing disk 168.

[0193] The outer diameter of the cylindrical portion 202, which is the outer diameter of the case member 170A, is smaller than the inner diameter of the inner cylinder 2 shown in Fig. 2. The inner diameter of the cylindrical portion 202A is larger than the outer diameter of the opening side disk valve 161 and the bottom side disk valve 167, which are the largest among the disks 160, 163, 164, 166, 169, the opening side disk valve 161, the opening side opening and closing disk 162, the passage forming disk 165, the bottom side disk valve 167, and the bottom side opening and closing disk 168, as shown in Fig. 5. The disks 160, 163, 164, 166, 169, the opening side disk valve 161, the opening side opening and closing disk 162, the passage forming disk 165, the bottom side disk valve 167, and the bottom side opening and closing disk 168 are all arranged on the inner side in the axial direction and the radial direction of the case member 170A.

[0194] The bottom portion 201A of the case member 170A has an inner plate-shaped portion 211A, a middle plate-shaped portion 212A, and an outer plate-shaped portion 213A.

[0195] The inner plate-shaped portion 211A is a substantially circular flat plate having a constant thickness. The mounting shaft portion 33 of the piston rod 31 fits into the inner periphery of the inner plate-shaped portion 211A.

[0196] The intermediate plate-shaped portion 212A extends from the outer peripheral edge of the inner plate-shaped portion 211A outward in the radial direction of the inner plate-shaped portion 211A. The surface of the intermediate plate-shaped portion 212A facing the disk 169 in the axial direction is located on the opposite side of the disk 169 from the inner plate-shaped portion 211A in the axial direction of the inner plate-shaped portion 211A to the outer side in the radial direction of the inner plate-shaped portion 211A. The thickness of the intermediate plate-shaped portion 212A becomes thinner as it approaches the outer side in the radial direction of the inner plate-shaped portion 211A.

[0197] The outer plate portion 213A is an effectively circular flat plate of a constant thickness, and extends from the outer peripheral edge of the intermediate plate portion 212A outward in the radial direction of the intermediate plate portion 212A. The outer plate portion 213A extends parallel to the inner plate portion 211A.

[0198] The bottom 201A is formed with a passage hole 215A penetrating the bottom 201A in the axial direction, i.e., the thickness direction. The passage hole 215A is formed across the intermediate plate-shaped portion 212A and the outer plate-shaped portion 213A. The bottom 201A is formed with a plurality of passage holes 215A of the same shape at equal intervals in the circumferential direction of the bottom 201A, with the radial positions of the bottom 201A aligned. The radius of the plurality of passage holes 215A to the outer end position in the radial direction of the bottom 201A is larger than the radius of the bottom side open-close disk 168. The radius of the plurality of passage holes 215A to the inner end position in the radial direction of the bottom 201A is smaller than the radius of the bottom side open-close disk 168.

[0199] The cylindrical portion 202A has a main body portion 221A, an opening side protrusion 222A, and a bottom side protrusion 223A.

[0200] The main body portion 221A is cylindrical and extends from the outer peripheral edge portion of the bottom portion 201A, i.e., the outer peripheral edge portion of the outer plate-shaped portion 213A, along the axial direction of the bottom portion 201A toward the discs 160, 163, 164, 166, 169, the opening side disc valve 161, the opening side opening / closing disc 162, the passage forming disc 165, the bottom side disc valve 167 and the bottom side opening / closing disc 168.

[0201] The opening-side protrusion 222A is provided at a middle position in the axial direction of the main body portion 221A, and protrudes inward from the main body portion 221A in the radial direction of the main body portion 221A. The opening-side protrusion 222A is provided around the entire circumference of the main body portion 221A, and is annular in shape.

[0202] The bottom side protrusion 223A is provided between the opening side protrusion 222A and the outer plate-shaped portion 213A in the axial direction of the main body portion 221A, and protrudes inward in the radial direction of the main body portion 221A from the main body portion 221A. The bottom side protrusion 223A is provided around the entire circumference of the main body portion 221A and is annular. The opening side protrusion 222A and the bottom side protrusion 223A have the same shape and therefore the same inner diameter. The opening side protrusion 222A and the bottom side protrusion 223A may have different shapes, and the inner diameter of the opening side protrusion 222A may be different from the inner diameter of the bottom side protrusion 223A.

[0203] The case member 170A is formed into the above-described shape by forging.

[0204] Similar to the opening side protrusion 222 of the case member 170, the opening side protrusion 222A of the case member 170A forms an opening side communicating passage 240 between itself and the opening side disc valve 161, and together with the opening side disc valve 161, forms a damping mechanism section 241A similar to the damping mechanism section 241, and a damping mechanism section 242A similar to the damping mechanism section 242.

[0205] Similar to bottom side protrusion 223 of case member 170, bottom side protrusion 223A of case member 170 forms a bottom side connecting passage 250 between it and bottom side disc valve 167, and together with bottom side disc valve 167 forms damping mechanism section 251A similar to damping mechanism section 251, and damping mechanism section 252A similar to damping mechanism section 252.

[0206] The damping mechanism section 241A and the damping mechanism section 251A constitute a second damping force generating mechanism 268A similar to the second damping force generating mechanism 268, and the damping mechanism section 242A and the damping mechanism section 252A constitute a second damping force generating mechanism 278A similar to the second damping force generating mechanism 278.

[0207] In the shock absorber 1A of the second embodiment described above, the case member 170A is formed by forging, so that the manufacturing cost can be suppressed.

[0208] It should be noted that a case member having a shape similar to that of the case member 170A can also be formed by sintering, and in this case, the manufacturing cost can be reduced. [Explanation of symbols]

[0209] 1,1A...shock absorber, 4...cylinder, 21...piston, 22...first chamber (chamber), 23...second chamber (chamber), 31...piston rod, 85,86...first damping force generating mechanism, 103...orifice portion, 132,152...first passage, 161...opening side disc valve 161 (second disc valve), 167...bottom side disc valve 167 (first disc valve), 170,170A...case member, 181...opening side communication hole (second communication hole), 191...bottom side communication hole (first communication hole), 240...opening side communication passage (communication passage), 244...opening side valve mechanism (second valve mechanism), 250...bottom side communication passage (communication passage) , 254...bottom valve mechanism (first valve mechanism), 265, 275...second passage, 268, 278...second damping force generating mechanism, L...oil (working fluid).

Claims

1. A cylinder in which a working fluid is sealed; a piston slidably disposed within the cylinder and dividing the interior of the cylinder into two chambers; a piston rod connected to the piston and extending to the outside of the cylinder; a first passage through which the working fluid flows from the upstream chamber to the downstream chamber as the piston moves; a first damping force generating mechanism that is provided in the first passage and operates in response to a moving speed of the piston relative to the cylinder to generate a damping force; a second passage provided separately from the first passage; an orifice portion provided in the second passage and configured to limit a flow rate of the second passage; a second damping force generating mechanism that is provided in the second passage, the second damping force generating mechanism having a first disk valve and a second disk valve, each of which has a fixed radial end and a free radial end, and that operates prior to the first damping force generating mechanism depending on the moving speed of the piston relative to the cylinder to generate a damping force; having a first valve mechanism that opens and closes a first communication hole that is provided in the first disk valve and communicates between an upstream side and a downstream side; a second valve mechanism that opens and closes a second communication hole that is provided in the second disk valve and communicates between an upstream side and a downstream side; A shock absorber comprising:

2. 2. The shock absorber according to claim 1, The first valve mechanism is formed to be able to open during an extension stroke in which the piston rod extends relative to the cylinder, The second valve mechanism is a shock absorber formed to be able to open during a compression stroke when the piston rod advances into the cylinder.

3. 2. The shock absorber according to claim 1, the first communication hole is formed to have an area larger than a pressure-receiving area of ​​the first disc valve that receives pressure from the upstream side of the working fluid, The second communication hole is formed to have an area larger than a pressure-receiving area where the second disc valve receives pressure from the upstream side of the working fluid.

4. 3. The shock absorber according to claim 2, the first valve mechanism is formed so that a pressure receiving area thereof that receives pressure from the working fluid from the upstream side is larger than a pressure receiving area of ​​the first disk valve that receives pressure from the working fluid from the upstream side, a shock absorber formed so that a pressure-receiving area of ​​the second valve mechanism that receives pressure from the working fluid from the upstream side is larger than a pressure-receiving area of ​​the second disc valve that receives pressure from the working fluid from the upstream side.

5. 3. The shock absorber according to claim 2, a communication passage provided separately from the second damping force generating mechanism so as to allow the working fluid to flow therethrough, the communication passage connecting an upstream side and a downstream side of the second damping force generating mechanism, The communication passage is formed between the first disc valve and a case member provided on a radial outer periphery of the second disc valve.

6. 6. The shock absorber according to claim 5, The case member is formed by pressing, sintering or forging.

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