Shock absorbers and damping valve systems

Abstract

To provide a shock absorber which can inhibit occurrence of abnormal noise, and to provide a damping valve device.SOLUTION: A shock absorber includes: a cylinder in which a working fluid is enclosed; a piston which partitions the interior of the cylinder; a first passage in which flow of the working fluid is generated by the piston moving in one direction; a first damping valve which provides a resistive force to flow of the working fluid from an upstream side chamber to a downstream side chamber of the first passage; a second passage in which flow of the working fluid is generated by the piston moving in the other direction; and a second damping disc valve which provides a resistive force to flow of the working fluid from an upstream side chamber to a downstream side chamber of the second passage. The second damping disc valve has: a third passage which constantly allows communication between the upstream side chamber and the downstream side chamber; and a fourth passage which communicates with the upstream side chamber. A variable chamber which communicates with the fourth passage and is partitioned by a partition member which moves in response to pressure change of the upstream side or the downstream side chamber is disposed overlapping with the second damping disc valve.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to shock absorbers and damping valve arrangements. This application claims priority based on Japanese Patent Application No. 2022-086551, filed on May 27, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Some shock absorbers have a body valve (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2009-287752 [Patent Document 2] Japanese Patent No. 5443227 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, there is a demand for suppressing the generation of abnormal noise in shock absorbers.

[0005] Therefore, an object of the present invention is to provide a shock absorber and a damping valve device that can suppress the generation of abnormal noise. [Means for solving the problem]

[0006] One aspect of the shock absorber according to the present invention comprises a cylinder in which a working fluid is sealed, a piston fitted in the cylinder and partitioning the interior of the cylinder, a first passage in which a flow of the working fluid is generated by movement of the piston in one direction, a first damping valve that provides resistance to the flow of the working fluid from an upstream chamber of the first passage to a downstream chamber, a second passage in which a flow of the working fluid is generated by movement of the piston in the other direction, and a second damping disc valve that provides resistance to the flow of the working fluid from the upstream chamber to the downstream chamber of the second passage, wherein the second damping disc valve has a third passage that always connects the upstream chamber with the downstream chamber and a fourth passage that connects with the upstream chamber, and a variable chamber that connects with the fourth passage and is partitioned by a partition member that moves in response to pressure changes in the upstream or downstream chamber, and is arranged over the second damping disc valve.

[0007] One aspect of the damping valve device according to the present invention is a damping valve device that is connected to a cylinder in which a working fluid is sealed, and that includes: a first passage through which a flow of the working fluid is generated by movement of a piston in the cylinder in one direction; a first damping valve that provides resistance to the flow of the working fluid from a chamber upstream of the first passage to a chamber downstream of the first passage; a second passage through which a flow of the working fluid is generated by movement of the piston in the other direction; and a second damping disc valve that provides resistance to the flow of the working fluid from the chamber upstream of the second passage to a chamber downstream of the second passage, wherein the second damping disc valve has a communication passage that communicates with the upstream chamber, and an accumulator mechanism that communicates with the communication passage and has a variable chamber partitioned by a partition member that moves in response to a pressure change in the upstream or downstream chamber is arranged on top of the second damping disc valve. [Effects of the Invention]

[0008] According to the above aspects of the present invention, it is possible to suppress the generation of abnormal noise. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a partial cross-sectional view showing a body valve and its periphery of the shock absorber of the first embodiment. [Figure 3] 3 is a partial cross-sectional view showing a portion III in FIG. 2 of a body valve of the shock absorber according to the first embodiment. [Figure 4] FIG. 3 is a hydraulic circuit diagram of a body valve of the shock absorber of the first embodiment. [Figure 5] 4 is a characteristic diagram showing simulation results of rod acceleration when transitioning from a compression stroke to an extension stroke in the shock absorber of the first embodiment and a shock absorber of a comparative example. FIG. [Figure 6] 4 is a characteristic diagram showing the characteristics of the damping force relative to the piston speed when the piston speed is high at a low piston frequency in the shock absorber of the first embodiment and a shock absorber of a comparative example. FIG. [Figure 7] 4 is a characteristic diagram showing the characteristics of the damping force relative to the piston speed when the piston speed is slow at a low piston frequency in the shock absorber of the first embodiment and a shock absorber of a comparative example. FIG. [Figure 8] 4 is a characteristic diagram showing the characteristics of the damping force relative to the piston speed when the piston speed is high at a high frequency in the shock absorber of the first embodiment and a shock absorber of a comparative example. FIG. [Figure 9] 4 is a characteristic diagram showing the characteristics of the damping force relative to the piston speed when the piston speed is slow at a high frequency in the shock absorber of the first embodiment and a shock absorber of a comparative example. FIG. [Figure 10] 4 is a characteristic diagram showing the characteristics of damping force relative to piston frequency when the piston speed is high in the shock absorber of the first embodiment and a shock absorber of a comparative example. FIG. [Figure 11] FIG. 6 is a partial cross-sectional view showing a main portion of a body valve of a shock absorber according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a partial cross-sectional view showing a main portion of a body valve of a shock absorber according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a partial cross-sectional view showing a partition member of the shock absorber of the third embodiment. [Figure 14]FIG. 11 is a bottom view showing a partition member of the shock absorber of the third embodiment. [Figure 15] FIG. 10 is a partial cross-sectional view showing a main portion of a body valve of a shock absorber according to a fourth embodiment of the present invention. [Figure 16] FIG. 10 is a partial cross-sectional view showing a partition member of the shock absorber of the fourth embodiment. [Figure 17] FIG. 10 is a plan view showing a partition member of the shock absorber of the fourth embodiment. [Figure 18] FIG. 10 is a hydraulic circuit diagram of a body valve of the shock absorber of the fourth embodiment. [Figure 19] FIG. 10 is a partial cross-sectional view showing a partition member of a shock absorber according to a fifth embodiment of the present invention. [Figure 20] FIG. 11 is a plan view showing a partition member of the shock absorber of the fifth embodiment. [Figure 21] FIG. 10 is a partial cross-sectional view showing a main portion of a body valve of a shock absorber according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] [First embodiment] A first embodiment of the present invention will be described below with reference to FIGS.

[0011] FIG. 1 shows a shock absorber 11 of a first embodiment. This shock absorber 11 is used in a suspension system of a vehicle such as an automobile or a railway vehicle. Specifically, the shock absorber 11 is a hydraulic shock absorber used in a suspension system of an automobile. The shock absorber 11 is provided with a cylinder 17 having an inner cylinder 15 and an outer cylinder 16. The inner cylinder 15 is cylindrical. The outer cylinder 16 is cylindrical with a bottom. The inner diameter of the outer cylinder 16 is larger than the outer diameter of the inner cylinder 15. The outer cylinder 16 is disposed radially outside the inner cylinder 15 and coaxially with the inner cylinder 15. A reservoir chamber 18 is formed between the outer cylinder 16 and the inner cylinder 15. The shock absorber 11 is a double-cylinder shock absorber.

[0012] The outer cylinder 16 has a body 20 and a bottom 21. The body 20 is cylindrical. The bottom 21 closes one axial end of the body 20. The end of the body 20 opposite the bottom 21 forms an opening 22. The opening 22 of the outer cylinder 16 is also provided at one axial end of the cylinder 17. The bottom 21 of the outer cylinder 16 is also provided at the other axial end of the cylinder 17. In other words, one axial end of the cylinder 17 is open as the opening 22, and the other axial end is closed as the bottom 21.

[0013] The shock absorber 11 includes a valve base 25 and a rod guide 26.

[0014] The valve base 25 is annular, and is provided at one axial end of the inner cylinder 15 and the outer cylinder 16. The valve base 25 constitutes a body valve 30, which is a damping valve device. One axial side of the outer periphery of the valve base 25 is a large diameter portion 31, and the other axial side of the outer periphery is a small diameter portion 32. The outer diameter of the large diameter portion 31 is larger than the outer diameter of the small diameter portion 32. Therefore, the outer periphery of the valve base 25 is stepped.

[0015] The valve base 25 is placed on the bottom 21 with the large diameter portion 31 axially positioned closer to the bottom 21 than the small diameter portion 32. At this time, the valve base 25 is positioned radially with respect to the outer cylinder 16 at the large diameter portion 31. A passage groove 33 that penetrates the valve base 25 radially is formed in the valve base 25 at the position of the large diameter portion 31 axially. Here, the space between the valve base 25 and the bottom 21 is in communication with the inner cylinder 15 and the outer cylinder 16 via the passage groove 33 formed in the valve base 25. The space between the valve base 25 and the bottom 21, like the space between the inner cylinder 15 and the outer cylinder 16, defines a reservoir chamber 18.

[0016] The rod guide 26 is annular and is provided at the other axial end of the inner cylinder 15 and the outer cylinder 16. The rod guide 26 is provided on the opening 22 side of the cylinder 17. The rod guide 26 has a large diameter portion 35 on one axial side of its outer periphery, and a small diameter portion 36 on the other axial side of its outer periphery. The outer diameter of the large diameter portion 35 is larger than the outer diameter of the small diameter portion 36. Therefore, the outer periphery of the rod guide 26 has a stepped shape. The large diameter portion 35 of the rod guide 26 fits into the inner periphery of the opening 22 side of the body portion 20 of the outer cylinder 16, with the small diameter portion 36 positioned closer to the bottom 21 than the large diameter portion 35.

[0017] One axial end of the inner cylinder 15 is fitted into the small diameter portion 32 on the outer periphery of the valve base 25. One axial end of the inner cylinder 15 is placed on the bottom 21 of the outer cylinder 16 via this valve base 25. The other axial end of the inner cylinder 15 is fitted into the small diameter portion 36 of the rod guide 26. This other end of the inner cylinder 15 is fitted into the trunk portion 20 of the outer cylinder 16 via the rod guide 26. In this state, the inner cylinder 15 is positioned axially and radially with respect to the outer cylinder 16.

[0018] The shock absorber 11 is provided with an annular rod seal 41. The rod seal 41 is provided on the opposite side of the bottom portion 21 of the rod guide 26 in the axial direction of the cylinder 17. This rod seal 41, like the rod guide 26, is fitted to the inner periphery of the body portion 20. An engaging portion 43 is formed on the outer cylinder 16 at the end opposite the bottom portion 21 of the body portion 20. The engaging portion 43 is formed by plastically deforming the body portion 20 radially inward by crimping, such as curling. The rod seal 41 is sandwiched between this engaging portion 43 and the rod guide 26. At this time, the rod seal 41 is pressed against the inner periphery of the body portion 20 by the rod guide 26. As a result, the rod seal 41 closes the opening 22 of the outer cylinder 16. Specifically, the rod seal 41 is an oil seal.

[0019] The shock absorber 11 is equipped with a piston 45. The piston 45 is slidably fitted in the inner tube 15 of the cylinder 17. The piston 45 divides the inner tube 15 into two chambers: a first chamber 48 and a second chamber 49. The first chamber 48 is provided between the piston 45 and the rod guide 26 in the inner tube 15. The second chamber 49 is provided between the piston 45 and the valve base 25 in the inner tube 15. The second chamber 49 is separated from the reservoir chamber 18 by the valve base 25. In the cylinder 17, oil L as a working fluid is sealed in the first chamber 48 and the second chamber 49. In the cylinder 17, gas G and oil L as working fluids are sealed in the reservoir chamber 18.

[0020] The shock absorber 11 is equipped with a piston rod 50. One axial end portion of the piston rod 50 is inserted inside the cylinder 17. The one end portion of the piston rod 50 is connected to the piston 45. An intermediate portion of the piston rod 50 in the axial direction passes through the rod guide 26 and the rod seal 41. The other axial end portion of the piston rod 50 extends to the outside of the cylinder 17. The piston rod 50 is made of metal, and passes through the first chamber 48. The piston rod 50 does not pass through the second chamber 49. Therefore, the first chamber 48 is a rod-side chamber through which the piston rod 50 passes. The second chamber 49 is a bottom-side chamber on the bottom 21 side of the cylinder 17. The portion of the piston rod 50 extending to the outside from the cylinder 17 is connected to the vehicle body.

[0021] The piston rod 50 has a main shaft portion 51 and a mounting shaft portion 52 . The outer diameter of the mounting shaft portion 52 is smaller than the outer diameter of the main shaft portion 51. The mounting shaft portion 52 side of the piston rod 50 is inserted into the cylinder 17.

[0022] The main shaft portion 51 of the piston rod 50 passes through the rod guide 26 and the rod seal 41. The rod guide 26 and the rod seal 41 are provided on the portion of the cylinder 17 from which the piston rod 50 extends. The rod guide 26 slidably supports the piston rod 50. The piston rod 50 is guided by the rod guide 26 on the outer peripheral surface of the main shaft portion 51. The piston rod 50 moves axially together with the piston 45 relative to the cylinder 17. During the extension stroke of the shock absorber 11, in which the piston rod 50 increases its protrusion from the cylinder 17, the piston 45 moves toward the first chamber 48. During the compression stroke of the shock absorber 11, in which the piston rod 50 decreases its protrusion from the cylinder 17, the piston 45 moves toward the second chamber 49.

[0023] The rod seal 41 is provided on the side of the cylinder 17 from which the piston rod 50 extends, i.e., on the side of the opening 22 of the outer cylinder 16. The rod seal 41, together with the rod guide 26, seals the gap between the body 20 of the outer cylinder 16 and the main shaft portion 51 of the piston rod 50, thereby restricting the oil L in the inner cylinder 15 and the gas G and oil L in the reservoir chamber 18 from leaking to the outside.

[0024] A passage 55 and a passage 56 are formed in the piston 45. Both the passage 55 and the passage 56 pass through the piston 45 in the axial direction. The passages 55, 56 can communicate between the first chamber 48 and the second chamber 49. The shock absorber 11 is equipped with a disc valve 57 and a disc valve 58. The disc valve 57 is provided on the side of the piston 45 opposite the bottom 21 in the axial direction. The disc valve 57 is annular and closes the passage 55 by abutting against the piston 45. The disc valve 58 is provided on the bottom 21 side of the piston 45 in the axial direction. The disc valve 58 is annular and closes the passage 56 by abutting against the piston 45. The disc valves 57, 58 are attached to the piston rod 50 together with the piston 45.

[0025] When the piston rod 50 moves toward the compression side, increasing the amount of penetration into the inner cylinder 15 and the outer cylinder 16, and the piston 45 moves in the direction narrowing the second chamber 49, the pressure in the second chamber 49 becomes higher than the pressure in the first chamber 48. Then, the disc valve 57 opens the passage 55, allowing the oil L in the second chamber 49 to flow into the first chamber 48. At that time, the disc valve 57 generates a damping force.

[0026] When the piston rod 50 moves toward the extension side, increasing the amount of protrusion from the inner cylinder 15 and the outer cylinder 16, and the piston 45 moves in a direction narrowing the first chamber 48, the pressure in the first chamber 48 becomes higher than the pressure in the second chamber 49. This causes the disc valve 58 to open the passage 56, allowing the oil L in the first chamber 48 to flow into the second chamber 49. At that time, the disc valve 58 generates a damping force.

[0027] A fixed orifice (not shown) is formed in at least one of the piston 45 and the disc valve 57. This fixed orifice allows communication between the first chamber 48 and the second chamber 49 via the passage 55 even when the disc valve 57 is in the most closed state of the passage 55.

[0028] A fixed orifice (not shown) is formed in at least one of the piston 45 and the disc valve 58. This fixed orifice allows communication between the first chamber 48 and the second chamber 49 via the passage 56 even when the disc valve 58 is in the most closed state of the passage 56.

[0029] As described above, the body valve 30 has a valve base 25 that separates the second chamber 49 from the reservoir chamber 18. The valve base 25 is a seamless, one-piece molded metal part. As shown in FIG. 2, the valve base 25 has a base portion 71 and legs 72.

[0030] The base portion 71 is in the shape of a perforated disk. The leg portion 72 is cylindrical and extends from the outer periphery of the base portion 71 to one side in the axial direction of the base portion 71. A part of the large diameter portion 31 is formed in the leg portion 72, and the remaining part of the large diameter portion 31 and the small diameter portion 32 are formed in the base portion 71. The above-mentioned passage groove 33 is formed in the leg portion 72, penetrating the leg portion 72 in the radial direction. The passage groove 33 opens at the end of the leg portion 72 opposite the base portion 71 in the axial direction. A plurality of passage grooves 33 are formed in the leg portion 72, spaced apart in the circumferential direction. The valve base 25 is placed on the bottom portion 21 of the outer cylinder 16 at the end of the leg portion 72 opposite the base portion 71 in the axial direction. At this time, the valve base 25 is positioned radially with respect to the outer cylinder 16.

[0031] A through hole 81 is formed in the radial center of the base portion 71 of the valve base 25. The base portion 71 has a base main body portion 82, an inner seat 83, and an inner seat 84.

[0032] The inner sheet 83 is annular and protrudes from the entire circumference of the edge of the base main body 82 on the through-hole 81 side in the radial direction to the opposite side from the leg 72 in the axial direction of the base main body 82.

[0033] The inner sheet 84 is annular, and protrudes from the entire circumference of the edge of the base main body 82 on the through-hole 81 side in the radial direction to the leg 72 side in the axial direction of the base main body 82.

[0034] The base portion 71 has an outer sheet 86 and an intermediate sheet 87 . The outer sheet 86 is annular, and protrudes from a portion of the base main body 82 radially outward of the inner sheet 83 toward the opposite side of the leg portion 72 in the axial direction of the base main body 82 .

[0035] The intermediate sheet 87 is annular, and protrudes from a position between the outer sheet 86 and the inner sheet 83 in the radial direction of the base main body 82 to the opposite side from the leg portion 72 in the axial direction of the base main body 82.

[0036] The base portion 71 also has an outer sheet 88. The outer sheet 88 is annular, and protrudes from a position between the leg portion 72 and the inner sheet 84 in the radial direction of the base main body portion 82 toward the leg portion 72 in the axial direction of the base main body portion 82.

[0037] The base portion 71 also has a protrusion 89. The protrusion 89 protrudes from the base main body portion 82 on the same side as the outer sheet 88 in the axial direction of the base main body portion 82. The protrusion 89 extends from the outer sheet 88 inward in the radial direction of the outer sheet 88. In the axial direction of the base main body portion 82, the protrusion 89 protrudes to a height that is lower from the base main body portion 82 than the protrusion height of the outer sheet 88 from the base main body portion 82. A plurality of protrusions 89 of the same shape are formed on the base portion 71 at equal intervals in the circumferential direction of the base portion 71.

[0038] An outer passage hole 91 penetrating the base main body 82 in the axial direction is formed in the base main body 82 between the outer sheet 86 and the intermediate sheet 87 in the radial direction. A plurality of outer passage holes 91 are provided in the base main body 82 at equal intervals in the circumferential direction of the base main body 82. The plurality of outer passage holes 91 are arranged between the outer sheet 88 and the leg portion 72 in the radial direction of the base main body 82. The plurality of outer passage holes 91 allow communication between the second chamber 49 and the reservoir chamber 18.

[0039] An inner passage hole 92 penetrating the base main body 82 in the axial direction is formed in the base main body 82 between the inner sheet 83 and the intermediate sheet 87 in the radial direction. A plurality of inner passage holes 92 are provided in the base main body 82 at equal intervals in the circumferential direction of the base main body 82. The plurality of inner passage holes 92 are arranged between the outer sheet 88 and the inner sheet 84 in the radial direction of the base main body 82. The plurality of inner passage holes 92 allow communication between the second chamber 49 and the reservoir chamber 18.

[0040] The body valve 30 has a pin member 101 that is inserted into the through-hole 81 of the valve base 25. The pin member 101 is a bolt that has a head 102 and a shaft 103 whose outer diameter is smaller than the outer diameter of the head 102.

[0041] The head 102 is engageable with a fastening tool. The shaft portion 103 is cylindrical and extends from the center of the radial direction of the head portion 102 to one side along the axial direction of the head portion 102. A male thread 104 is formed on the outer periphery of the shaft portion 103 on the side opposite to the head portion 102 in the axial direction.

[0042] The body valve 30 has, in axial order from the valve base 25 side opposite the bottom 21 of the valve base 25, one valve disc 110, one valve disc 111, one disc 112, one spring disc 113, and one regulating disc 114. The valve discs 110, 111, disc 112, spring disc 113, and regulating disc 114 are all made of metal. The valve discs 110, 111, and disc 112 are all perforated circular flat plates of a certain thickness, into which the shaft portion 103 of the pin member 101 can be fitted.

[0043] The valve disc 110 has an outer diameter slightly larger than the outer diameter of the outer seat 86 of the valve base 25. The valve disc 110 is flexible and abuts against the inner seat 83, outer seat 86, and intermediate seat 87 to close the outer passage hole 91. A passage hole 121 is formed in the valve disc 110 between the inner seat 83 and the intermediate seat 87 in the radial direction, penetrating the valve disc 110 in the axial direction. The passage hole 121 is an elongated hole extending in the circumferential direction of the valve disc 110. A notch 122 is formed on the outer peripheral side of the valve disc 110. The notch 122 extends radially across the portion of the outer seat 86 that contacts the valve disc 110. An orifice 123 is formed within the notch 122.

[0044] The valve disc 111 has an outer diameter equal to that of the valve disc 110. The valve disc 111 is flexible and abuts against the valve disc 110. A passage hole 125 is formed in the valve disc 111 between the radially inner seat 83 and the radially outer seat 86, penetrating the valve disc 111 in the axial direction. The valve disc 111 has a plurality of passage holes 125 formed at equal intervals around the circumferential direction of the valve disc 111. In the radial direction of the valve discs 110, 111, the passage holes 125 are offset from the notches 122 and partially overlap with the passage holes 121. The communication portion between the passage holes 121 and 125 forms an orifice 128.

[0045] The disc 112 has an outer diameter equal to the outer diameter of the inner seat 83 of the valve base 25, and is entirely disposed inside the passage hole 125 in the radial direction of the valve disc 111.

[0046] The spring disc 113 has a base portion 131 and a spring plate portion 132 . The base plate 131 is a circular flat plate with a hole and a constant thickness, and the shaft 103 of the pin member 101 can be fitted inside the base plate 131. The base plate 131 has an outer diameter slightly larger than the outer diameter of the disk 112.

[0047] The spring plate portions 132 extend radially outward from the outer peripheral edge of the base plate portion 131. The spring plate portions 132 are flexible. A plurality of spring plate portions 132 are formed on the spring disc 113 at equal intervals around the circumferential direction of the base plate portion 131. The spring plate portions 132 are inclined relative to the base plate portion 131 so that the spring plate portions 132 are further away from the base plate portion 131 in the axial direction of the base plate portion 131 as they move radially outward. All of the multiple spring plate portions 132 extend on the same side of the base plate portion 131 in the axial direction of the base plate portion 131. The spring disc 113 abuts against the disc 112 at the base plate portion 131, and the multiple spring plate portions 132 extend from the base plate portion 131 toward the valve disc 111 in the axial direction and abut against an annular portion of the valve disc 111 that is outer than the passage hole 125 in the radial direction.

[0048] The regulating disc 114 is thicker and more rigid than the valve discs 110 and 111 and the spring disc 113. The regulating disc 114 has a main plate portion 141 and an outer circumferential stepped portion 142. The main plate portion 141 is a circular flat plate with a hole and a constant thickness, and the shaft portion 103 of the pin member 101 can be fitted inside the main plate portion 141.

[0049] The outer peripheral step portion 142 is annular, and protrudes radially outward from the entire outer periphery of the main plate portion 141. The outer peripheral step portion 142 is formed slightly offset to one side in the axial direction relative to the main plate portion 141. The regulating disk 114 abuts against the base plate portion 131 of the spring disk 113 at the main plate portion 141, and the outer peripheral step portion 142 protrudes axially toward the valve disk 111 relative to the main plate portion 141. A passage hole 143 that passes through the main plate portion 141 in the axial direction is formed in the main plate portion 141 at a predetermined radially intermediate position. A plurality of passage holes 143 are formed in the main plate portion 141 at equal intervals in the circumferential direction of the main plate portion 141. The passage hole 143 constantly connects the second chamber 49 to the inner passage hole 92 of the valve base 25 via the gap between the spring plate portions 132 of the spring disc 113, the passage hole 125 of the valve disc 111, and the passage hole 121 of the valve disc 110.

[0050] As shown in FIG. 3, the body valve 30 has, on the axial leg portion 72 side of the base portion 71 of the valve base 25, in order from the axial base portion 71 side, one disc 151, one opening / closing disc 152, one coned disc spring 153, one valve disc 154, one valve disc 155, one valve disc 156, multiple discs, specifically three valve discs 157, one disc 158, and one disc 159.

[0051] The discs 151 and 158, the opening / closing disc 152, the conical spring 153, the valve discs 154 to 157, and the disc 159 are all made of metal. The discs 151 and 158, the valve discs 154 to 157, and the disc 159 are all circular flat plates with holes of a certain thickness, into which the shaft portion 103 of the pin member 101 can be fitted. The opening / closing disc 152 and the conical spring 153 are all annular, into which the shaft portion 103 of the pin member 101 can be fitted.

[0052] The disc 151 has an outer diameter slightly smaller than the outer diameter of the inner seat 84 of the valve base 25 .

[0053] The open-close disc 152 is in a natural state before being assembled into the body valve 30 and has a perforated circular flat plate shape with a constant thickness. The open-close disc 152 is flexible. The open-close disc 152 has an outer diameter larger than the outer diameter of the disc 151. The open-close disc 152 has an outer diameter that does not come into contact with the multiple protrusions 89 of the valve base 25.

[0054] The disc spring 153 is formed by press molding from a single flat plate material. The disc spring 153 has a base plate portion 161 and an outer peripheral tapered plate portion 162. The disc spring 153 is flexible.

[0055] When the disc spring 153 is in its natural state before being assembled into the body valve 30, the base plate portion 161 is in the shape of a perforated circular flat plate of a constant thickness. The base plate portion 161 is formed with a passage hole 163 that penetrates the base plate portion 161 in the axial direction of the base plate portion 161 at a position whose diameter is larger than the outer diameter of the disk 151 and smaller than the outer diameter of the open-close disk 152. The base plate portion 161 is formed with a plurality of passage holes 163 at equal intervals in the circumferential direction of the base plate portion 161.

[0056] The outer peripheral tapered plate portion 162 widens in a tapered shape from the outer peripheral edge of the base plate portion 161. The diameter of the outer peripheral tapered plate portion 162 increases as it moves away from the flat base plate portion 161 in the axial direction of the base plate portion 161. The outer peripheral tapered plate portion 162 is annular and is formed around the entire circumference of the base plate portion 161.

[0057] The boundary between the base plate portion 161 and the outer peripheral tapered plate portion 162 of the disc spring 153 is a corner portion 164. The corner portion 164 is provided around the entire periphery of the disc spring 153 and has a circular shape.

[0058] The valve disc 154 has an outer diameter slightly larger than the outer diameter of the outer seat 88 of the valve base 25. The valve disc 154 is flexible and abuts against the Belleville spring 153 and the outer seat 88. The valve disc 154 has notches 171 formed on its outer periphery. The notches 171 extend radially across the portion of the outer seat 88 that contacts the valve disc 154. The valve disc 154 has multiple notches 171 formed at equal intervals around the circumferential direction of the valve disc 154. The valve disc 154 has passage holes 172 that penetrate the valve disc 154 in the axial direction of the valve disc 154. The passage holes 172 are located radially inward of the inscribed circles of the multiple notches 171 of the valve disc 154. The passage holes 172 are arc-shaped elongated holes that extend circumferentially of the valve disc 154.

[0059] The valve disc 155 has an outer diameter equal to that of the valve disc 154. The valve disc 155 is flexible. A passage hole 181 is formed in the valve disc 155, penetrating the valve disc 155 in the axial direction of the valve disc 155. The passage hole 181 is located at a position overlapping with the passage hole 172 of the valve disc 154 in the radial direction of the valve discs 154, 155. The passage hole 181 is an arc-shaped elongated hole extending in the circumferential direction of the valve disc 155.

[0060] The valve disc 156 has an outer diameter equal to the outer diameters of the valve discs 154, 155. The valve disc 156 is flexible. A notch 191 is formed on the outer periphery of the valve disc 156. A passage hole 192 is formed in the valve disc 156, penetrating the valve disc 156 in the axial direction of the valve disc 156. The passage hole 192 is located at a position overlapping the passage hole 181 of the valve disc 155 in the radial direction of the valve discs 155, 156. The passage hole 192 is an arc-shaped elongated hole extending in the circumferential direction of the valve disc 154. The notch 191 is in communication with the passage hole 192.

[0061] In all cases, the elongated passage holes 172, 181, 192 that are long in the circumferential direction of the valve discs 154 to 156 overlap in position in the radial direction of the valve discs 154 to 156. This ensures that the passage holes 172, 181, 192 overlap over a sufficient area regardless of the phase of the valve discs 154 to 156.

[0062] The plurality of valve discs 157 have an outer diameter equal to the outer diameter of the valve discs 154 to 156. The valve discs 157 are flexible. The disc 158 has an outer diameter smaller than the outer diameters of the valve discs 154-157.

[0063] The disc 159 has an outer diameter that is larger than the outer diameter of the disc 158 and slightly smaller than the outer diameter of the valve discs 154-157.

[0064] When assembling the body valve 30, the pin member 101 is stacked on the head 102 in this order with the disc 159, disc 158, multiple valve discs 157, valve disc 156, valve disc 155, valve disc 154, conical spring 153, open / close disc 152, disc 151, valve base 25, valve disc 110, valve disc 111, disc 112, spring disc 113, and regulating disc 114 shown in FIG. 2, with the shaft portion 103 of the pin member 101 fitted inside each disc.

[0065] At this time, the disc spring 153 shown in Figure 3 is oriented so that the corner portion 164 is positioned on the opposite side from the valve disc 154. At this time, the valve base 25 is oriented so that the inner seat 84 abuts against the disc 151. At this time, the spring disc 113 shown in Figure 2 is oriented so that the spring plate portion 132 abuts against the valve disc 111. At this time, the regulating disc 114 is oriented so that the outer peripheral step portion 142 protrudes from the main plate portion 141 toward the valve disc 111 in the axial direction.

[0066] In this state, the nut 201 is screwed onto the male thread 104 of the pin member 101 that protrudes beyond the main plate portion 141 of the regulating disk 114. As a result, at least the inner circumferential sides of the disk 159, disk 158, the multiple valve disks 157, valve disk 156, valve disk 155, valve disk 154, coned disc spring 153, open / close disk 152, disk 151, valve base 25 shown in FIG. 3, and the valve disk 110, valve disk 111, disk 112, spring disk 113, and regulating disk 114 shown in FIG. 2 are clamped to the head 102 of the pin member 101 and the nut 201.

[0067] When the disc spring 153 is installed in the body valve 30, as shown in FIG. 3 , the inner peripheral portion of the base plate portion 161 of the disc spring 153 becomes flat, and the outer peripheral portion of the base plate portion 161 deforms in a tapered shape, moving away from the valve disc 154 in the axial direction as it moves radially outward. In this state, the outer peripheral tapered plate portion 162 of the disc spring 153 tapers toward the valve disc 154 in the axial direction as it moves radially outward, and its tip abuts against the valve disc 154. At this time, the outer peripheral tapered plate portion 162 of the disc spring 153 abuts against the entire circumference of the annular portion of the valve disc 154 between the notch 171 and the passage hole 172 in the radial direction. Therefore, the disc spring 153 is disposed so as to cover the passage hole 172 of the valve disc 154. In this state, the entire passage hole 163 of the disc spring 153 is radially aligned with the passage hole 172 of the valve disc 154.

[0068] When the open-close disc 152 is assembled into the body valve 30, the inner peripheral portion thereof becomes flat. In this state, the outer peripheral portion of the open-close disc 152 is pressed by the outer peripheral portion of the base plate portion 161 of the disc spring 153, and the open-close disc 152 is deformed in a tapered shape so that the radially outer portion moves away from the valve disc 154 in the axial direction. As a result, the open-close disc 152 comes into surface contact with the base plate portion 161 of the disc spring 153 due to its elastic force. As a result, the open-close disc 152 entirely covers the multiple passage holes 163 of the disc spring 153, closing the multiple passage holes 163.

[0069] The body valve 30 assembled in this manner is placed on the bottom 21 of the outer cylinder 16 with the small diameter portion 32 fitted onto one axial end of the inner cylinder 15, as shown in Figure 2. As a result, the body valve 30 is placed in communication with the cylinder 17.

[0070] In the body valve 30, the space between the intermediate seat 87 and the outer seat 86 of the valve base 25 and the insides of the multiple outer passage holes 91 form a first passage 211 that can communicate between the reservoir chamber 18 and the second chamber 49. In the body valve 30, the valve discs 110, 111, the disc 112, and the spring disc 113 form a first damping valve 212 that opens and closes the first passage 211. A flow of hydraulic fluid L, which is a working fluid, is generated in the first passage 211 by the movement of the piston 45 shown in FIG. 1 in one direction, that is, the extension direction. The first damping valve 212 shown in FIG. 2 applies resistance to the flow of hydraulic fluid L from the reservoir chamber 18 on the upstream side of the first passage 211 to the second chamber 49 on the downstream side. The first damping valve 212 and the orifice 123 are provided in the first passage 211 and constitute a first extension-side damping force generating mechanism 215 that suppresses the flow of oil L flowing within the first passage 211 and generates a damping force.

[0071] In the body valve 30, a second passage 221 is formed between the orifice 128 provided in the first damping valve 212, the base main body portion 82, the inner seat 83, and the intermediate seat 87 of the valve base 25, and the inside of the multiple inner passage holes 92. The second passage 221 includes a variable chamber 220 surrounded by the base main body portion 82, the inner seat 84, the outer seat 88, and the multiple protrusions 89 of the valve base 25 shown in FIG. 3, the disc 151, the open / close disc 152, the conical spring 153, and the valve disc 154. The second passage 221 can communicate between the second chamber 49 shown in FIG. 2 and the reservoir chamber 18.

[0072] The body valve 30 serves as a second damping disc valve 222 that opens and closes a second passage 221 when valve discs 154 to 157 shown in Fig. 3 move away from and into contact with the outer seat 88. Therefore, the second damping disc valve 222 is provided in the body valve 30. In the second passage 221, a flow of hydraulic fluid L is generated by movement of the piston 45 shown in Fig. 1 in the other direction, that is, the contraction direction. The second damping disc valve 222 shown in Fig. 2 applies resistance to the flow of hydraulic fluid L from the second chamber 49 on the upstream side of the second passage 221 to the reservoir chamber 18 on the downstream side.

[0073] In the body valve 30, the inside of the notch 171 of the valve disc 154 of the second damping disc valve 222 shown in FIG. 3 serves as a third passage 231. The third passage 231 is an orifice that constantly connects the variable chamber 220 and the reservoir chamber 18. The third passage 231 is provided in the second passage 221. The third passage 231 allows the second passage 221 to constantly connect the reservoir chamber 18 and the second chamber 49 shown in FIG. 2. In other words, the third passage 231 constantly connects the upstream reservoir chamber 18 and the downstream second chamber 49 when the piston 45 shown in FIG. 1 moves in the extension direction, and constantly connects the upstream second chamber 49 and the downstream reservoir chamber 18 when the piston 45 moves in the contraction direction. The second damping disc valve 222 and the third passage 231, which is an orifice, shown in Figure 3 are provided in the second passage 221 and constitute a compression-side second damping force generating mechanism 225 that suppresses the flow of oil liquid L flowing through the second passage 221 and generates a damping force.

[0074] In the body valve 30, the inside of the notch 191 and the passage hole 192 of the valve disc 156 of the second damping disc valve 222, the inside of the passage hole 181 of the valve disc 155, and the inside of the passage hole 172 of the valve disc 154 form a fourth passage 241 (communication passage) that always communicates with the reservoir chamber 18 on the upstream side when the piston 45 moves in the extension direction shown in FIG. 1. In other words, the second damping disc valve 222 has the fourth passage 241. Note that a portion of the fourth passage 241 may be provided in the pin member 101.

[0075] In the fourth passage 241, the inside of the notch 191 of the valve disc 156 forms an orifice 242. In the fourth passage 241, the inside of the passage hole 192 of the valve disc 156, the inside of the passage hole 181 of the valve disc 155, and the inside of the passage hole 172 of the valve disc 154 form an intermediate chamber 243.

[0076] The third passage 231 and the fourth passage 241 are provided in the second damping disc valve 222. The third passage 231 and a part of the fourth passage 241 are formed in the valve disc 154 of the second damping disc valve 222, which is seated on the outer seat 88.

[0077] In the body valve 30, the base main body portion 82, inner seat 84, outer seat 88 and multiple protrusions 89 of the valve base 25, the disc 151, the opening / closing disc 152, the belleville spring 153 and the valve disc 154 constitute a pressure accumulation mechanism 251 including a variable chamber 220.

[0078] In the pressure accumulating mechanism 251, a portion surrounded by the opening-closing disc 152, the disc spring 153, and the valve disc 154 constitutes a variable chamber 252. In other words, the pressure accumulating mechanism 251 has the variable chamber 252. The variable chamber 252 is partitioned from the variable chamber 220 of the second passage 221 by the disc spring 153 and the opening-closing disc 152. The disc spring 153 and the opening-closing disc 152 constitute a partition member 255 that partitions the variable chamber 252 and the variable chamber 220. The variable chamber 252 communicates with the fourth passage 241.

[0079] The partitioning member 255 moves in response to pressure changes in the upstream reservoir chamber 18 or the downstream second chamber 49 when the piston 45 shown in FIG. 1 moves in the extension direction. The partitioning member 255 shown in FIG. 3 moves in response to pressure changes in the upstream second chamber 49 or the downstream reservoir chamber 18 when the piston 45 shown in FIG. 1 moves in the retraction direction. The partitioning member 255 shown in FIG. 3 is made up of a Belleville spring 153. During the extension stroke of the piston 45 shown in FIG. 1, the partitioning member 255 enlarges the variable chamber 252 formed between the partitioning member 255 and the valve disc 154 shown in FIG. 3 and reduces the variable chamber 220, while during the retraction stroke of the piston 45 shown in FIG. 1, the variable chamber 220 shown in FIG. 3 is enlarged and the variable chamber 252 is reduced.

[0080] When the disc spring 153 deforms in a direction to increase the size of the variable chamber 252, it abuts against the protruding portion 89 of the valve base 25 at the corner 164, preventing further deformation. When the disc spring 153 deforms in a direction to increase the size of the variable chamber 220 ... at the corner 164, preventing further deformation by the valve disc 154. The outer peripheral tapered plate portion 162 of the disc spring 153 always abuts against the valve disc 154 over the entire circumference, thereby sealing between the variable chamber 252 and the variable chamber 220. Here, because the protruding portions 89 are formed intermittently in the circumferential direction of the valve base 25, the second passage 221 is not blocked even when the disc spring 153 abuts against the protruding portion 89 at the corner 164.

[0081] When the pressure difference between the upstream variable chamber 252 shown in FIG. 3 and the downstream variable chamber 220 reaches a predetermined value during movement of the piston 45 shown in FIG. 1 in the extension direction, the opening-closing disc 152 moves away from the disc spring 153, opening the passage hole 163 of the disc spring 153 and connecting the variable chamber 252 to the variable chamber 220, i.e., the second chamber 49 shown in FIG. 2. The passage hole 163 of the disc spring 153 and the opening-closing disc 152 shown in FIG. 3 constitute a relief mechanism 258 that relieves pressure inside the variable chamber 252 after the pressure difference between the upstream variable chamber 252 shown in FIG. 3 and the downstream variable chamber 220 reaches a predetermined value during movement of the piston 45 shown in FIG. 1 in the extension direction. In other words, the partitioning member 255 is provided with the relief mechanism 258.

[0082] The pressure accumulation mechanism 251 has a variable chamber 252 that communicates with the fourth passage 241. The variable chamber 252 is separated from the variable chamber 220 of the second passage 221 by a partition member 255 shown in Figure 3 that moves in response to a pressure change in the reservoir chamber 18 on the upstream side or the second chamber 49 on the downstream side when the piston 45 shown in Figure 1 moves in the extension direction.

[0083] The variable chambers 220, 252 are formed by the second damping disc valve 222. The variable chambers 220, 252 are arranged so as to overlap the second damping disc valve 222 in the axial direction of the second damping disc valve 222. The pressure accumulator mechanism 251 including the variable chambers 220, 252 is arranged so as to overlap the second damping disc valve 222 in the axial direction of the second damping disc valve 222.

[0084] The hydraulic circuit diagram of the body valve 30 described above is as shown in FIG. The body valve 30 is provided with a first extension-side damping force generation mechanism 215 including a first damping valve 212 and an orifice 123 in a first extension-side passage 211 that connects the reservoir chamber 18 and the second chamber 49. The body valve 30 is also provided with a second compression-side damping force generation mechanism 225 including an orifice 128, a second damping disc valve 222, and a third passage 231 in a second passage 221 that connects the second chamber 49 and the reservoir chamber 18. The body valve 30 is also provided with a variable chamber 220 of a pressure accumulator mechanism 251 between the orifice 128 of the second passage 221 and the second damping force generation mechanism 225. The body valve 30 is also provided with a variable chamber 252 of the pressure accumulator mechanism 251 that connects to the reservoir chamber 18 via an intermediate chamber 243 of a fourth passage 241 and an orifice 242. In addition, the body valve 30 is provided with a relief mechanism 258 between the variable chamber 252 of the pressure accumulating mechanism 251 and the variable chamber 220, which regulates the flow of oil liquid L from the variable chamber 220 to the variable chamber 252 and allows the flow of oil liquid L from the variable chamber 252 to the variable chamber 220.

[0085] Next, the main operation of the body valve 30 will be described.

[0086] During the extension stroke in which the piston rod 50 moves toward the extension side, when only the extension-side first damping force generating mechanism 215 is operating, in the low-speed range in which the moving speed of the piston 45 (hereinafter referred to as the piston speed) is slower than a predetermined value, the oil L from the reservoir chamber 18 flows into the second chamber 49 mainly via the orifice 123 of the extension-side first passage 211. This generates a damping force with orifice characteristics (the damping force is approximately proportional to the square of the piston speed). The characteristic of the damping force relative to the piston speed in the low-speed range is that the rate of increase of the damping force becomes relatively high as the piston speed increases.

[0087] Furthermore, during the extension stroke, when the piston speed is in a high-speed range equal to or greater than a predetermined value, the oil L from the reservoir chamber 18 opens the first damping valve 212 in the first extension passage 211 and flows into the second chamber 49. This generates a damping force with valve characteristics (the damping force is approximately proportional to the piston speed). Therefore, the damping force characteristics relative to the piston speed in the high-speed piston speed range are such that the rate of increase in the damping force relative to an increase in piston speed is slightly lower than in the low-speed range described above.

[0088] During the compression stroke in which the piston rod 50 moves toward the compression side, if only the second damping force generating mechanism 225 on the compression side is operating, in the low-speed range where the piston speed is slower than a predetermined value, the oil L from the second chamber 49 flows into the reservoir chamber 18 mainly via the third passage 231, which is the orifice of the second passage 221. This generates a damping force with orifice characteristics (the damping force is approximately proportional to the square of the piston speed). Therefore, the characteristic of the damping force relative to the piston speed in the low-speed range is that the rate of increase of the damping force becomes relatively high as the piston speed increases.

[0089] Furthermore, during the compression stroke, when the piston speed is in a high speed range equal to or greater than a predetermined value, the oil L from the second chamber 49 opens the second damping disc valve 222 in the second passage 221 and flows into the reservoir chamber 18. This generates a damping force with valve characteristics (the damping force is approximately proportional to the piston speed). Therefore, the damping force characteristic relative to the piston speed in the high speed range is such that the rate of increase in the damping force relative to an increase in piston speed is slightly lower than in the low speed range described above.

[0090] The above is the case where only the first damping force generating mechanism 215 and the second damping force generating mechanism 225 are in operation, but in the first embodiment, the pressure accumulator mechanism 251 varies the damping force according to the piston frequency during the extension stroke and compression stroke, even if the piston speed is the same.

[0091] That is, during the extension stroke, the pressure in the second chamber 49 becomes lower than the pressure in the reservoir chamber 18, and the oil L in the reservoir chamber 18 is introduced into the first passage 211 and flows into the second chamber 49 via the first damping force generation mechanism 215. In addition, the oil L in the reservoir chamber 18 is introduced into the variable chamber 252 of the pressure accumulator mechanism 251 from the fourth passage 241, deforming the partition member 255 and expanding the variable chamber 252. At that time, the oil L in the variable chamber 220, which is being contracted, is discharged into the second chamber 49 via the second passage 221.

[0092] During the extension stroke when the piston speed is low and the piston frequency is low, the stroke of the piston 45 is large. Therefore, in the early stage of introduction of hydraulic fluid L from the reservoir chamber 18 into the variable chamber 252 via the fourth passage 241, the partition member 255 bends significantly, causing the corner portion 164 of the disc spring 153 to abut against the protruding portion 89 of the valve base 25, thereby suppressing further deformation. As a result, the variable chamber 252 is placed in a state where an increase in volume is suppressed, and the variable chamber 252 is unable to absorb the increase in the amount of hydraulic fluid L being introduced. This increases the force with which the hydraulic fluid L in the reservoir chamber 18 presses the first damping valve 212 in the opening direction. This causes the first damping valve 212 to open, allowing the hydraulic fluid L to flow into the second chamber 49 via the first passage 211. Therefore, during the extension stroke when the piston speed is low and the piston frequency is low, the damping force characteristics are the same as when the pressure accumulation mechanism 251 is not present.

[0093] On the other hand, even when the piston speed is low, i.e., below a predetermined value, the stroke of the piston 45 is small during the extension stroke when the piston frequency is high, i.e., above a predetermined value, and therefore the volume of hydraulic fluid L introduced from the reservoir chamber 18 into the variable chamber 252 via the fourth passage 241 is small. For this reason, the partitioning member 255 only bends slightly, and does not come into contact with the protruding portion 89 of the valve base 25, or is deformable even if it does come into contact with the protruding portion 89. For this reason, most of the increase in hydraulic fluid L introduced from the reservoir chamber 18 into the variable chamber 252 via the fourth passage 241 is absorbed by the bending of the partitioning member 255. As a result, the force with which the hydraulic fluid L in the reservoir chamber 18 pushes the first damping valve 212 in the opening direction is suppressed more than when the piston frequency is low, i.e., below a predetermined value, and the damping force is lower and softer than at low frequencies.

[0094] Therefore, during the extension stroke, when the piston speed is low and the piston frequency is high and equal to or greater than a predetermined value, the damping force characteristics are softer and lower than the damping force characteristics when the piston frequency is low and equal to or greater than a predetermined value. As a result, during the extension stroke when the piston speed is low and the piston frequency is high and equal to or greater than a predetermined value, where abnormal noise is likely to occur, a sudden change in oil pressure when the first damping valve 212 opens is suppressed, making it possible to reduce the acceleration of the piston rod 50 (hereinafter referred to as rod acceleration), and suppressing the generation of abnormal noise.

[0095] Furthermore, when the piston speed is high, equal to or greater than a predetermined value, the partition member 255 bends significantly, causing the disc spring 153 to abut against the protrusion 89 of the valve base 25 at the corner 164. Further deformation is suppressed, and the open-close disc 152 deforms and separates from the disc spring 153. In other words, the relief mechanism 258 opens. This allows the oil L in the variable chamber 252 to flow into the second chamber 49 via the second passage 221, which includes the variable chamber 220. This relief function reduces the pressure load on the disc spring 153, ensuring durability. At the same time, the amount of oil L moving into the second chamber 49 during the extension stroke can be increased, suppressing excessive pressure reduction in the second chamber 49 and suppressing cavitation.

[0096] During the compression stroke, the pressure in the second chamber 49 becomes higher than the pressure in the reservoir chamber 18, and the oil L in the second chamber 49 is introduced into the second passage 221 and flows into the reservoir chamber 18 via the second damping force generating mechanism 225. In addition, the oil L in the second chamber 49 is introduced into the variable chamber 220 of the pressure accumulating mechanism 251, deforming the partition member 255 and expanding the variable chamber 220. At that time, the oil L in the contracting variable chamber 252 is discharged into the reservoir chamber 18 via the fourth passage 241.

[0097] During a compression stroke when the piston frequency is lower than a predetermined value, the stroke of the piston 45 is large, and therefore, at the beginning of the introduction of hydraulic fluid L from the second chamber 49 into the variable chamber 220, the partition member 255 bends significantly, and deformation is suppressed by the valve disc 154. As a result, the volume of the variable chamber 220 remains unchanged, and the variable chamber 220 is unable to absorb the increase in the amount of hydraulic fluid L being introduced. This causes the pressure in the variable chamber 220 to rise to a high pressure, and the force pushing the second damping disc valve 222 in the opening direction increases. As a result, the second damping disc valve 222 opens, and hydraulic fluid L flows into the reservoir chamber 18 through the gap with the outer seat 88. Therefore, during a compression stroke when the piston frequency is low and lower than a predetermined value, the damping force characteristics are the same as when the pressure accumulation mechanism 251 is not present.

[0098] On the other hand, during the compression stroke when the piston frequency is equal to or higher than a predetermined value, the stroke of the piston 45 is small, and therefore the volume of the oil liquid L introduced from the second chamber 49 into the variable chamber 220 is small, and the partition member 255 is therefore easily deformed with a small amount of deflection. As a result, most of the increase in the oil liquid L introduced from the second chamber 49 into the variable chamber 220 is absorbed by the deflection of the partition member 255. As a result, the pressure in the variable chamber 220 is low, and the valve opening pressure of the second damping disc valve 222 does not increase. For this reason, when the piston frequency is high, the damping force is lower and softer than when the piston frequency is low.

[0099] Therefore, during the compression stroke, when the piston frequency is a high frequency equal to or greater than a predetermined value, the damping force characteristics are softer and the damping force is reduced compared to when the piston frequency is a low frequency lower than the predetermined value. As a result, during the compression stroke when the piston frequency is a high frequency equal to or greater than a predetermined value, which is prone to generating abnormal noise, a sudden change in oil pressure when the second damping disc valve 222 opens is suppressed, making it possible to reduce rod acceleration and suppress the generation of abnormal noise.

[0100] The dashed line in Fig. 5 shows the simulation results of the rod acceleration of the shock absorber 11 of the first embodiment equipped with the body valve 30 having the pressure accumulation mechanism 251. The solid line in Fig. 5 shows the simulation results of the rod acceleration of a shock absorber equipped with a body valve of a comparative example having a conventional structure that differs in that the body valve 30 does not have the pressure accumulation mechanism 251 and the fourth passage 241. The two-dot chain line in Fig. 5 shows the simulation results of the damping force. It can be seen from Fig. 5 that the peak value of the rod acceleration caused by the opening of the first damping valve 212 is lower in the shock absorber 11 of the first embodiment compared to the shock absorber of the comparative example.

[0101] The dashed lines in Figures 6 and 7 show the simulation results of the damping force when the piston speed of the shock absorber 11 of the first embodiment alone is 0.6 m / s and a low frequency input is applied. The solid lines in Figures 6 and 7 show the simulation results of the damping force when the piston speed of the shock absorber of the comparative example alone is 0.6 m / s and a low frequency input is applied.

[0102] 6 and 7, it can be seen that the shock absorber 11 of the first embodiment maintains the damping force waveform almost identical to that of the shock absorber of the comparative example when the piston frequency is low, and can maintain equivalent performance.

[0103] The dashed lines in Figures 8 and 9 show the simulation results of the damping force when the piston speed of the shock absorber 11 of the first embodiment alone is 0.6 m / s and a high frequency is input. The solid lines in Figures 8 and 9 show the simulation results of the damping force when the piston speed of the shock absorber of the comparative example alone is 0.6 m / s and a high frequency is input.

[0104] 8 and 9, it can be seen that in the shock absorber 11 of the first embodiment, when the piston frequency is high, the damping force on the extension side of the first damping valve 212 of the body valve 30 is almost unchanged compared to the shock absorber of the comparative example. This is because the first damping valve 212 of the body valve 30 has a lower differential pressure than the disc valve 58 on the extension side of the piston 45. Also, in the shock absorber 11 of the first embodiment, when the piston frequency is high, the second damping disc valve 222 of the body valve 30, which has a large contribution to the damping force on the compression side, has a slightly lower damping force after opening, as shown in the range surrounded by the dashed dotted line X1 in Fig. 8 and the range surrounded by the dashed dotted line X2 in Fig. 9, but the peak value remains the same as that of the shock absorber of the comparative example.

[0105] The dashed line in Figure 10 shows the frequency characteristics of the damping force when the piston speed of the shock absorber 11 of the first embodiment is 0.3 m / s. The solid line in Figure 10 shows the frequency characteristics of the damping force when the piston speed of the shock absorber of the comparative example is 0.3 m / s. From Figure 10, it can be seen that, in terms of frequency dependence, the shock absorber 11 of the first embodiment, which has the pressure accumulator mechanism 251, exhibits a slight decrease in the compression damping force at high piston frequencies, but maintains almost the same performance as the shock absorber of the comparative example, which does not have a pressure accumulator mechanism. The shock absorber 11 of the first embodiment can improve quietness (noise and vibration) and harshness while maintaining the basic performance of conventional shock absorbers without a pressure accumulator mechanism. The shock absorber 11 also has the effect of improving ride comfort by reducing high-frequency input at the piston frequency.

[0106] The above-mentioned Patent Documents 1 and 2 disclose shock absorbers having a body valve. However, there is a demand for suppressing the generation of abnormal noise in shock absorbers.

[0107] In the shock absorber 11 of the first embodiment, the body valve 30 has a first passage 211 through which a flow of oil L is generated by unidirectional movement of the piston 45, a first damping valve 212 that provides resistance to the flow of oil L from the reservoir chamber 18 on the upstream side of the first passage 211 to the second chamber 49 on the downstream side, a second passage 221 through which a flow of oil L is generated by movement of the piston 45 in the other direction, and a second damping disc valve 222 that provides resistance to the flow of oil L from the second chamber 49 on the upstream side of the second passage 221 to the reservoir chamber 18 on the downstream side. In the body valve 30, the second damping disc valve 222 has a third passage 231 that always connects the reservoir chamber 18 on the upstream side with the second chamber 49 on the downstream side, and a fourth passage 241 that connects with the reservoir chamber 18 on the upstream side. Therefore, in the shock absorber 11, when the first damping valve 212 is opened during the extension stroke where the piston frequency is high and abnormal noise is prominent, the body valve 30 can introduce the oil L from the reservoir chamber 18 to the variable chamber 252. Therefore, in the shock absorber 11, when the first damping valve 212 is opened during the extension stroke where the piston frequency is high and abnormal noise is prominent, the body valve 30 can suppress a sudden change in oil pressure and reduce rod acceleration, thereby suppressing the generation of abnormal noise. As a result, it is possible to suppress abnormal noise and ensure damping force even at extremely low piston speeds.

[0108] In the shock absorber 11 of the first embodiment, the body valve 30 communicates with the fourth passage 241, and a variable chamber 252 partitioned by a partition member 255 that moves in response to pressure changes in the upstream reservoir chamber 18 or the downstream second chamber 49 is disposed overlapping the second damping disc valve 222. In other words, the pressure accumulator mechanism 251 including the variable chamber 252 is disposed overlapping the second damping disc valve 222. This allows the shock absorber 11 to have a compact configuration.

[0109] In the shock absorber 11 of the first embodiment, the third passage 231 and the fourth passage 241 are formed in the valve disc 154 of the second damping disc valve 222, which is seated on the outer seat 88. Therefore, the shock absorber 11 can be further made compact in configuration.

[0110] In the shock absorber 11 of the first embodiment, the partition member 255 is composed of a disc spring 153 that enlarges the variable chamber 252 formed between the partition member 255 and the valve disc 154 during the extension stroke of the piston 45 and reduces the variable chamber 252 during the compression stroke, thereby making it possible to make the shock absorber 11 compact and suppressing costs.

[0111] In the shock absorber 11 of the first embodiment, the partitioning member 255 is provided with a relief mechanism 258 that relieves pressure inside the variable chamber 252 after the differential pressure between the upstream variable chamber 252 and the downstream variable chamber 220 during the extension stroke of the piston 45 reaches a predetermined value. This makes it possible to suppress excessive deformation of the disc spring 153 and improve the durability of the disc spring 153. Furthermore, the shock absorber 11 can increase the amount of oil L moving from the reservoir chamber 18 to the second chamber 49 using the relief mechanism 258 during the extension stroke, thereby compensating for a lack of flow rate caused by the first damping valve 212 in the high piston speed range. Therefore, the shock absorber 11 can suppress excessive pressure reduction in the second chamber 49 and suppress cavitation. Furthermore, since the partitioning member 255 is provided with the relief mechanism 258, the shock absorber 11 can achieve a more compact configuration.

[0112] In the shock absorber 11 of the first embodiment, the second damping disc valve 222 is provided in the body valve 30, and therefore, it is possible to effectively suppress abnormal noise caused by the operation of the body valve 30. Furthermore, even if the pressure accumulator mechanism 251 is provided in the body valve 30, it is possible to configure it compactly, and therefore the stroke length of the piston rod 50 is not sacrificed.

[0113] The shock absorber 11 of the first embodiment has a pressure accumulation mechanism 251 between the valve base 25 having the outer seat 88 of the body valve 30 and the second damping disc valve 222 that opens and closes the outer seat 88, thereby further suppressing an increase in the axial length of the body valve 30.

[0114] [Second embodiment] Next, the second embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 11. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0115] As shown in FIG. 11, a shock absorber 11A of the second embodiment has a body valve 30A that is partially different from the body valve 30 instead of the body valve 30.

[0116] The body valve 30A has a pressure accumulation mechanism 251A that is partially different from the pressure accumulation mechanism 251 in place of the pressure accumulation mechanism 251. The pressure accumulation mechanism 251A has a partition member 255A that is partially different from the partition member 255 in place of the partition member 255. The partition member 255A has a disc spring 153A that is partially different from the disc spring 153 in place of the disc spring 153.

[0117] The disc spring 153A is also formed by press molding from a single flat plate material. The disc spring 153A has a base plate portion 161 and an outer peripheral tapered plate portion 162 similar to the disc spring 153, as well as an outermost peripheral plate portion 271. The outermost peripheral plate portion 271 extends radially outward from the outer peripheral edge of the outer peripheral tapered plate portion 162. The outermost peripheral plate portion 271 is annular and is formed around the entire circumference of the outer peripheral tapered plate portion 162.

[0118] The disc spring 153A has a curved portion 272 between the outer peripheral tapered plate portion 162 and the outermost peripheral plate portion 271. The curved portion 272 is provided over the entire circumference of the disc spring 153A and has a circular shape.

[0119] When incorporated into the body valve 30A, the inner peripheral portion of the base plate portion 161 of the disc spring 153A becomes flat, and the outer peripheral portion of the base plate portion 161 deforms in a tapered shape so that it moves away from the valve disc 154 in the axial direction as it moves radially outward. In this state, the disc spring 153A extends toward the valve disc 154 in a tapered shape so that the outer peripheral tapered plate portion 162 moves closer to the valve disc 154 in the axial direction as it moves radially outward. In this state, the curved portion 272 of the disc spring 153A abuts over the entire circumference against the annular portion of the valve disc 154 between the notch 171 and the passage hole 172 in the radial direction. In this state, the disc spring 153A extends in a tapered shape so that the outermost peripheral plate portion 271 moves away from the valve disc 154 in the axial direction as it moves radially outward.

[0120] The body valve 30A has a second passage 221A that is partially different from the second passage 221 in place of the second passage 221. The second passage 221A has a variable chamber 220A that is partially different from the variable chamber 220 in place of the variable chamber 220. The variable chamber 220A is surrounded by the base main body portion 82, inner seat 84, outer seat 88, and multiple protrusions 89 of the valve base 25, the disc 151, the partition member 255A, and the valve disc 154.

[0121] The hydraulic circuit diagram of the body valve 30A is the same as that of the body valve 30.

[0122] In the shock absorber 11A of the second embodiment, the body valve 30A operates in the same manner as the body valve 30.

[0123] The shock absorber 11A and its body valve 30A of the second embodiment achieve the same effects as those of the first embodiment. In addition, in the shock absorber 11A, the disc spring 153A of the body valve 30A thereof always abuts over the entire circumference of the annular portion between the notch 171 and the passage hole 172 in the radial direction of the valve disc 154, at the curved surface formed by bending the curved portion 272. In this way, because the disc spring 153A abuts against the valve disc 154 at the curved surface of the curved portion 272, it is possible to improve the sealing performance of the abutting portion with the valve disc 154 compared to the disc spring 153 that abuts against the valve disc 154 at the edge portion at the tip of the outer peripheral tapered plate portion 162.

[0124] [Third embodiment] Next, the third embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Figures 12 to 14. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0125] 12, the shock absorber 11B of the third embodiment has a body valve 30B that is partially different from the body valve 30 instead of the body valve 30. The body valve 30B has a pressure accumulation mechanism 251B that is partially different from the pressure accumulation mechanism 251 instead of the pressure accumulation mechanism 251. The pressure accumulation mechanism 251B has a partition member 255B that is different from the partition member 255 instead of the partition member 255. The pressure accumulation mechanism 251B has a disk 280 that is similar to the disk 151.

[0126] The partitioning member 255B is capable of fitting the shaft portion 103 of the pin member 101 inside. The partitioning member 255B has a substrate disk 281 and an outer peripheral disk 282. The substrate disk 281 and the outer peripheral disk 282 are both made of metal. 13 and 14, in the natural state before being assembled into the body valve 30B, the partitioning member 255B has a substrate disk 281 in the form of a perforated circular flat plate with a constant thickness. In addition, in the natural state before being assembled into the body valve 30B, the partitioning member 255B has an outer peripheral disk 282 in the form of a perforated circular flat plate with a constant thickness. In the natural state before being assembled into the body valve 30B, the partitioning member 255B has an outer diameter of the outer peripheral disk 282 that is the same as the outer diameter of the substrate disk 281, and an inner diameter of the outer peripheral disk 282 that is larger than the inner diameter of the substrate disk 281. The outer peripheral disk 282 is coaxial with the substrate disk 281 and is fixed to one axial side of the substrate disk 281 by welding.

[0127] When assembling the body valve 30B, the pin member 101 shown in Figure 12 is stacked on the head 102 in this order with the disk 159, disk 158, multiple valve disks 157, valve disk 156, valve disk 155, valve disk 154, disk 280, partition member 255B, disk 151, and valve base 25 fitted into the shaft portion 103 of the pin member 101. At this time, the partition member 255B is oriented so that the outer peripheral disk 282 is located on the valve disk 154 side. Here, the thickness of the outer peripheral disk 282 is greater than the thickness of the disk 280.

[0128] The partitioning member 255B is clamped between the discs 151 and 280 by fastening the head 102 of the pin member 101 and the nut 201 at the inner circumferential side of the substrate disc 281. When assembled into the body valve 30B in this manner, the partitioning member 255B has a flat plate-like portion on the inner circumferential side of the substrate disc 281, and the outer circumferential side of the substrate disc 281 is tapered so that it moves away from the valve disc 154 in the axial direction toward the radially outward direction. In this state, the partitioning member 255B has a tapered outer circumferential disc 282 that abuts against the valve disc 154 and moves away from the valve disc 154 in the axial direction toward the radially outward direction. At this time, the outer circumferential disc 282 abuts against the annular portion of the valve disc 154 between the notch 171 and the passage hole 172 in the radial direction over the entire circumference. Therefore, the partitioning member 255B is provided so as to cover the passage hole 172 of the valve disc 154.

[0129] The body valve 30B has a second passage 221B that is partially different from the second passage 221 in place of the second passage 221. The second passage 221B has a variable chamber 220B that is partially different from the variable chamber 220 in place of the variable chamber 220. The variable chamber 220B is surrounded by the base main body portion 82, inner seat 84, outer seat 88, and multiple protrusions 89 of the valve base 25, the disc 151, the partition member 255B, and the valve disc 154.

[0130] In the body valve 30B, the base main body portion 82, inner seat 84, outer seat 88, and multiple protrusions 89 of the valve base 25, the partitioning member 255B, the valve disc 154, and the discs 151 and 280 constitute a pressure accumulating mechanism 251B including a variable chamber 220B. In the pressure accumulating mechanism 251B, the portion surrounded by the partitioning member 255B, the disc 280, and the valve disc 154 constitutes a variable chamber 252B. The variable chamber 252B is partitioned from the variable chamber 220B of the second passage 221B by the partitioning member 255B. The variable chamber 252B communicates with the fourth passage 241. When the outer peripheral disc 282 abuts against the valve disc 154 along the entire circumference, the partitioning member 255B seals the variable chamber 252B from the variable chamber 220B.

[0131] The partitioning member 255B moves in response to pressure changes in the upstream reservoir chamber 18 or the downstream second chamber 49 (see FIG. 2) when the piston 45 (see FIG. 1) moves in the extension direction. The partitioning member 255B moves in response to pressure changes in the upstream second chamber 49 (see FIG. 2) or the downstream reservoir chamber 18 when the piston 45 (see FIG. 1) moves in the contraction direction. The partitioning member 255B increases the size of the variable chamber 252B and decreases the size of the variable chamber 220B during the extension stroke of the piston 45 (see FIG. 1), while it increases the size of the variable chamber 220B and decreases the size of the variable chamber 252B during the contraction stroke of the piston 45 (see FIG. 1).

[0132] The variable chambers 220B, 252B are formed by the second damping disc valve 222B. The variable chambers 220B, 252B are arranged to overlap the second damping disc valve 222B in the axial direction of the second damping disc valve 222B. The pressure accumulation mechanism 251B including the variable chambers 220B, 252B is arranged to overlap the second damping disc valve 222B in the axial direction of the second damping disc valve 222B.

[0133] During the extension stroke when the piston speed is in the low speed range, the partitioning member 255B enlarges variable chamber 252B, with the outer peripheral disc 282 remaining in contact with the valve disc 154 over the entire circumference. Furthermore, during the compression stroke, the partitioning member 255B enlarges variable chamber 220B. Here, during the extension stroke when the piston speed is in the high speed range, the outer peripheral disc 282 of the partitioning member 255B separates from the valve disc 154, connecting variable chamber 252B to variable chamber 220B. At that time, the base disc 281 of the partitioning member 255B abuts against the protrusion 89 of the valve base 25, suppressing further deformation.

[0134] The shock absorber 11B and its body valve 30B of the third embodiment have substantially the same effects as those of the first embodiment.

[0135] [Fourth embodiment] Next, the fourth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Figures 15 to 18. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0136] 15, a shock absorber 11C of the fourth embodiment has a body valve 30C that is partially different from the body valve 30 instead of the body valve 30. The body valve 30C has a valve base 25C that is partially different from the valve base 25 instead of the valve base 25.

[0137] The valve base 25C has a base portion 71C that is partially different from the base portion 71 in place of the base portion 71. The base portion 71C differs from the base portion 71 in that the protrusion 89 is not provided.

[0138] The body valve 30C is provided with, on the axial leg portion 72 side of the base portion 71C, in order from the axial base portion 71C side, one disc 151 similar to the above, one valve disc 154 similar to the above, one valve disc 155 similar to the above, one disc 291, one partition member 255C, one disc 292, one valve disc 156C, multiple valve discs, specifically three valve discs 157 similar to the above, one disc 158 similar to the above, and one disc 159 similar to the above.

[0139] Valve disc 156C and discs 291, 292 are all made of metal. Valve disc 156C and discs 291, 292 are all circular flat plates with holes of a constant thickness, inside which shaft portion 103 of pin member 101 can be fitted. Partition member 255C is annular, inside which shaft portion 103 of pin member 101 can be fitted.

[0140] The disks 291 and 292 are common parts having the same shape. The disks 291 and 292 have an outer diameter smaller than the passage hole 181 of the valve disk 155.

[0141] As shown in FIGS. 16 and 17, the partition member 255C has a substrate disk 301 and a pair of outer peripheral disks 302 and 303 of the same shape. The substrate disk 301 and the pair of outer disks 302 and 303 are both made of metal.

[0142] In the partitioning member 255C, the substrate disk 301 is a circular flat plate with a fixed thickness and holes, inside which the shaft portion 103 of the pin member 101 can be fitted, as shown in FIG. 15 . The substrate disk 301 is flexible. In addition, in the partitioning member 255C, a pair of outer peripheral disks 302, 303 are also circular flat plates with a fixed thickness and holes. The pair of outer peripheral disks 302, 303 of the partitioning member 255C have the same outer diameter as the substrate disk 301, and have inner diameters larger than the inner diameter of the substrate disk 301.

[0143] As shown in Fig. 17, the outer peripheral disc 302 is coaxial with the substrate disc 301 and is fixed by welding to one axial side of the substrate disc 301. The outer peripheral disc 303 shown in Fig. 16 is coaxial with the substrate disc 301 and is fixed by welding to the other axial side of the substrate disc 301 opposite the outer peripheral disc 302. As shown in Fig. 15, the outer diameter of the partition member 255C, i.e., the outer diameters of the substrate disc 301 and the pair of outer peripheral discs 302 and 303, are equal to the outer diameters of the valve discs 154, 155, and 157. The thickness of the outer peripheral disc 302 is equal to the thickness of the disc 291, and the thickness of the outer peripheral disc 303 is equal to the thickness of the disc 292.

[0144] The valve disc 156C has an outer diameter equal to the outer diameters of the valve discs 154, 155, and 157. The valve disc 156C is flexible. A notch 191C is formed on the outer periphery of the valve disc 156C.

[0145] When assembling the body valve 30C, the pin member 101 is stacked on the head 102 in this order with the disk 159, disk 158, multiple valve disks 157, valve disk 156C, disk 292, partition member 255C, disk 291, valve disk 155, valve disk 154, disk 151, and valve base 25C, with the shaft portion 103 of the pin member 101 fitted inside each of them.

[0146] At least the inner circumferential side of each of disc 159, disc 158, multiple valve discs 157, valve disc 156C, disc 292, partition member 255C, disc 291, valve disc 155, valve disc 154, and disc 151 is clamped to head 102 of pin member 101 and inner seat 84 of valve base 25C. The inner circumferential side of substrate disc 301 of partition member 255C is clamped to discs 291 and 292.

[0147] The body valve 30C has a second passage 221C that is partially different from the second passage 221 in place of the second passage 221. The second passage 221C has a variable chamber 220C that is partially different from the variable chamber 220 in place of the variable chamber 220. The variable chamber 220C is formed by a portion surrounded by the base main body portion 82, inner seat 84, and outer seat 88 of the valve base 25C, the disc 151, and the valve disc 154, the passage holes 172 and 181 of the valve discs 154 and 155, and a portion surrounded by the partition member 255C, the valve disc 155, and the disc 291.

[0148] The body valve 30C is a second damping disc valve 222C that opens and closes a second passage 221C by the valve discs 154, 155, 156C, 157 and the partition member 255C moving away from and contacting the outer seat 88. A flow of hydraulic fluid L, which is a working fluid, is generated in the second passage 221C by the movement of the piston 45 (see FIG. 1) in the compression direction. The second damping disc valve 222C applies resistance to the flow of hydraulic fluid L from the second chamber 49 (see FIG. 2) on the upstream side of the second passage 221C to the reservoir chamber 18 on the downstream side. The second damping disc valve 222C and a third passage 231, which is an orifice, are provided in the second passage 221C, and constitute a compression-side second damping force generation mechanism 225C that generates a damping force by suppressing the flow of hydraulic fluid L flowing in the second passage 221C.

[0149] In the body valve 30C, the inside of the notch 191C of the valve disc 156C serves as a fourth passage 241C (communication passage) that is always in communication with the upstream reservoir chamber 18 when the piston 45 (see FIG. 1) moves in the extension direction. In other words, the second damping disc valve 222C has a fourth passage 241C. The fourth passage 241C is an orifice.

[0150] A part of the variable chamber 220C of the second passage 221C and the third passage 231 are formed in the valve disc 154 seated on the outer seat 88 of the second damping disc valve 222C.

[0151] In the body valve 30C, the base main body portion 82, inner seat 84, outer seat 88 of the valve base 25C, valve discs 154, 155, 156C, partition member 255C, and discs 151, 291, 292 constitute a pressure accumulating mechanism 251C including a variable chamber 220C.

[0152] In pressure accumulation mechanism 251C, the portion surrounded by valve disc 156C, partition member 255C, and disc 292 constitutes variable chamber 252C. Variable chamber 252C is partitioned from variable chamber 220C of second passage 221C by partition member 255C. Variable chamber 252C communicates with fourth passage 241C.

[0153] The partitioning member 255C moves in response to pressure changes in the upstream reservoir chamber 18 or the downstream second chamber 49 (see FIG. 2) when the piston 45 (see FIG. 1) moves in the extension direction. The partitioning member 255C moves in response to pressure changes in the upstream second chamber 49 (see FIG. 2) or the downstream reservoir chamber 18 when the piston 45 (see FIG. 1) moves in the contraction direction. The partitioning member 255C increases the size of the variable chamber 252C and decreases the size of the variable chamber 220C during the extension stroke of the piston 45 (see FIG. 1), while increasing the size of the variable chamber 220C and decreasing the size of the variable chamber 252C during the contraction stroke of the piston 45 (see FIG. 1).

[0154] When partitioning member 255C deforms in a direction to increase variable chamber 252C, once it has deformed a predetermined amount, substrate disk 301 abuts against valve disk 155, suppressing further deformation. When partitioning member 255C deforms in a direction to increase variable chamber 220C, once it has deformed a predetermined amount, substrate disk 301 abuts against valve disk 156C, suppressing further deformation. The outer peripheral disk 302 of partitioning member 255C is always in abutment against valve disk 155 over the entire circumference.

[0155] The pressure accumulation mechanism 251C has a variable chamber 252C that communicates with the fourth passage 241C. The variable chamber 252C is separated from the second passage 221C by a partition member 255C that moves in response to a pressure change in the upstream reservoir chamber 18 or the downstream second chamber 49 (see FIG. 2) when the piston 45 (see FIG. 1) moves in the extension direction.

[0156] The variable chambers 220C, 252C are formed by the second damping disc valve 222C. The variable chamber 252C is disposed inside the second damping disc valve 222C. The variable chambers 220C, 252C are disposed on the second damping disc valve 222C so as to overlap with the second damping disc valve 222C in the axial direction of the second damping disc valve 222C. The pressure accumulation mechanism 251C including the variable chambers 220C, 252C is disposed on the second damping disc valve 222C so as to overlap with the second damping disc valve 222C in the axial direction of the second damping disc valve 222C.

[0157] The hydraulic circuit diagram of the body valve 30C described above is as shown in FIG. The body valve 30C is provided with an orifice 128 and a compression-side second damping force generation mechanism 225C including a second damping disc valve 222C and a third passage 231 in a second passage 221C that connects the second chamber 49 and the reservoir chamber 18. The body valve 30C also has a variable chamber 220C between the orifice 128 of the second passage 221C and the second damping force generation mechanism 225C. The body valve 30C also has a variable chamber 252C of a pressure accumulator mechanism 251C that connects to the reservoir chamber 18 via a fourth passage 241C that is an orifice. The body valve 30C is not provided with a relief mechanism.

[0158] Next, the main operation of the body valve 30C will be described.

[0159] During the extension stroke, the pressure in the second chamber 49 (see FIG. 2) becomes lower than the pressure in the reservoir chamber 18 shown in FIG. 15, and the oil L in the reservoir chamber 18 is introduced into the first passage 211 and flows to the second chamber 49 (see FIG. 2) via the first damping force generating mechanism 215 (see FIG. 2). In addition, the oil L in the reservoir chamber 18 is introduced from the fourth passage 241C into the variable chamber 252C of the pressure accumulating mechanism 251C, deforming the partition member 255C and expanding the variable chamber 252C. At that time, the oil L in the contracted variable chamber 220C is discharged into the second chamber 49 (see FIG. 2) via the second passage 221C.

[0160] During the extension stroke when the piston frequency is low and the piston is at a frequency lower than a predetermined frequency, the stroke of the piston 45 (see FIG. 1) is large. Therefore, in the early stage of introduction of hydraulic fluid L from the reservoir chamber 18 into the variable chamber 252C via the fourth passage 241C, the partition member 255C bends significantly, causing the substrate disk 301 to abut against the valve disk 155, suppressing further deformation. As a result, the variable chamber 252C is placed in a state where an increase in volume is suppressed, and the variable chamber 252C is unable to absorb the increased amount of hydraulic fluid L being introduced. This increases the force with which the hydraulic fluid L in the reservoir chamber 18 pushes the first damping valve 212 (see FIG. 2) in the opening direction. This causes the first damping valve 212 (see FIG. 2) to open, causing the hydraulic fluid L to flow into the second chamber 49 (see FIG. 2) via the first passage 211. Therefore, during the extension stroke when the piston frequency is low and the piston is at a frequency lower than a predetermined frequency, the damping force characteristics are the same as when the pressure accumulation mechanism 251C is not present.

[0161] On the other hand, during the extension stroke when the piston frequency is a high frequency equal to or higher than a predetermined value, the stroke of the piston 45 (see FIG. 1) is small, and therefore the volume of the oil L introduced from the reservoir chamber 18 into the variable chamber 252C via the fourth passage 241C is small. For this reason, the partitioning member 255C also has a small amount of deflection, and does not come into contact with the valve disc 155, or is able to deform even if it does come into contact with the valve disc 155. For this reason, most of the increase in the oil L introduced from the reservoir chamber 18 into the variable chamber 252C via the fourth passage 241C is absorbed by the deflection of the partitioning member 255C. As a result, the force with which the oil L in the reservoir chamber 18 pushes the first damping valve 212 (see FIG. 2) in the opening direction is suppressed more than when the piston frequency is low frequency below a predetermined value, and the damping force is lower and softer than at low frequencies.

[0162] During the compression stroke, the pressure in the second chamber 49 (see FIG. 2) becomes higher than the pressure in the reservoir chamber 18, and the oil L in the second chamber 49 (see FIG. 2) is introduced into the second passage 221C and flows into the reservoir chamber 18 via the second damping force generating mechanism 225C. In addition, the oil L in the second chamber 49 (see FIG. 2) is introduced into the variable chamber 220C of the pressure accumulating mechanism 251C, deforming the partition member 255C and expanding the variable chamber 220C. At that time, the oil L in the contracting variable chamber 252C is discharged into the reservoir chamber 18 via the fourth passage 241C.

[0163] During a compression stroke when the piston frequency is lower than a predetermined value, the stroke of the piston 45 (see FIG. 1) is large. Therefore, in the early stage of introduction of hydraulic fluid L from the second chamber 49 (see FIG. 2) into the variable chamber 220C, the partition member 255C bends significantly and abuts against the valve disc 156C, suppressing further deformation. As a result, the volume of the variable chamber 220C remains unchanged, and the variable chamber 220C is no longer able to absorb the increased amount of hydraulic fluid L being introduced. This causes the pressure in the variable chamber 220C to rise to a high pressure, increasing the force pushing the second damping disc valve 222C in the opening direction. This causes the second damping disc valve 222C to open, allowing hydraulic fluid L to flow into the reservoir chamber 18 through the gap with the outer seat 88. Therefore, during a compression stroke when the piston frequency is low and lower than a predetermined value, the damping force characteristics are the same as when the pressure accumulation mechanism 251C is not present.

[0164] On the other hand, during the compression stroke when the piston frequency is equal to or greater than a predetermined value, the stroke of the piston 45 (see FIG. 1) is small, and therefore the volume of the oil L introduced from the second chamber 49 (see FIG. 2) into the variable chamber 220C is small, and the partition member 255C is easily deformed with a small amount of deflection. As a result, most of the increase in the oil L introduced from the second chamber 49 (see FIG. 2) into the variable chamber 220C is absorbed by the deflection of the partition member 255C. As a result, the variable chamber 220C is at a low pressure, and the opening pressure of the second damping disc valve 222C does not increase. Therefore, during the compression stroke, when the piston frequency is high, the damping force is lower and softer than when the piston frequency is low.

[0165] The shock absorber 11C and its body valve 30C of the fourth embodiment have substantially the same effects as those of the first embodiment.

[0166] Although shock absorber 11C of the fourth embodiment does not have a relief mechanism, partition member 255C, which deforms due to the differential pressure between variable chambers 220C and 252C, is sandwiched between valve disc 155 and valve disc 156C, and deformation is limited by valve disc 155 or valve disc 156, even at high speeds, thereby suppressing excessive stress buildup.

[0167] [Fifth embodiment] Next, the fifth embodiment will be described, focusing on the differences from the fourth embodiment, mainly with reference to Figures 19 and 20. Note that parts common to the fourth embodiment will be designated by the same names and symbols.

[0168] 19, a shock absorber 11D of the fifth embodiment has a body valve 30D that is partially different from the body valve 30C instead of the body valve 30C. The body valve 30D has a partition member 255D instead of the partition member 255C.

[0169] The partition member 255D has a partition member main body 153D and an opening / closing disc 152D. The partition member main body 153D and the opening / closing disc 152D can both have the shaft portion 103 of the pin member 101 fitted inside.

[0170] The partition member main body 153D has a substrate disk 301D and a pair of outer peripheral disks 302D and 303D of the same shape. The substrate disk 301D and the pair of outer peripheral disks 302D and 303D are both made of metal. In the natural state before being assembled into the body valve 30D, the partition member main body 153D has a substrate disk 301D in the shape of a perforated circular flat plate of a uniform thickness. The substrate disk 301D is flexible. A passage hole 163D penetrating the substrate disk 301D in the axial direction is formed at a radially intermediate position in the substrate disk 301D. As shown in FIG. 20 , the substrate disk 301D has a plurality of passage holes 163D, specifically thirteen, formed at equal intervals around its circumferential direction.

[0171] 19, the partitioning member main body 153D is a pair of peripheral disks 302D, 303D in the form of a circular flat plate with a fixed thickness and having holes. The outer diameters of the pair of peripheral disks 302D, 303D of the partitioning member main body 153D are the same as the outer diameter of the substrate disk 301D. The inner diameters of the pair of peripheral disks 302D, 303D are larger than the inner diameter of the substrate disk 301D.

[0172] As shown in Fig. 20, the outer peripheral disk 302D is coaxial with the substrate disk 301D and fixed by welding to one side of the substrate disk 301D in the axial direction. The outer peripheral disk 303D shown in Fig. 19 is coaxial with the substrate disk 301D and fixed by welding to the other side of the substrate disk 301D, opposite the axial side from the outer peripheral disk 302D. The outer diameter of the partition member main body 153D, i.e., the outer diameter of the substrate disk 301D and the pair of identically shaped outer peripheral disks 302D and 303D, is equal to the outer diameter of the valve disks 154, 155, 156C, and 157. The substrate disk 301D has a plurality of passage holes 163D formed radially inward of the pair of outer peripheral disks 302D and 303D.

[0173] The open-close disc 152D is a circular flat plate with holes of a certain thickness in its natural state before being incorporated into the body valve 30D. The open-close disc 152D is flexible. The open-close disc 152D is capable of closing the multiple passage holes 163D by coming into surface contact with the substrate disc 301D of the partition member main body 153D.

[0174] Body valve 30D has disk 291D, which has a thickness different from disk 291, and disk 292D, which has a thickness different from disk 292. Disks 291D and 292D have the same outer diameter. The thickness of outer disk 302D is thinner than that of disk 291D. The thickness of outer disk 303D is thicker than that of disk 292D.

[0175] When assembling the body valve 30D, the pin member 101 is stacked on the head 102 in this order with the disk 159, disk 158, multiple (specifically, two) valve disks 157, valve disk 156C, disk 292D, partition member main body 153D, opening / closing disk 152D, disk 291D, valve disk 155, valve disk 154, disk 151 and valve base 25C, with the shaft portion 103 of the pin member 101 fitted inside each of them.

[0176] At least the inner circumferential side of each of disc 159, disc 158, multiple valve discs 157, valve disc 156C, disc 292C, partitioning member main body 153D, open-close disc 152D, disc 291D, valve disc 155, valve disc 154 and disc 151 is clamped to head 102 of pin member 101 and inner seat 84 of valve base 25D. For partitioning member main body 153D, the inner circumferential side of substrate disc 301D is clamped to discs 291D and 292D.

[0177] When incorporated into the body valve 30D, the substrate disk 301D of the partition member main body 153D has both its inner and outer peripheral portions flat, and the intermediate portion between them is deformed in a tapered shape so that it approaches the valve disk 155 in the axial direction as it moves radially outward.

[0178] When incorporated into the body valve 30D, the opening-closing disc 152D has an inner peripheral portion that is flat, and an outer peripheral portion that is tapered in accordance with the substrate disc 301D so that the radially outward portion approaches the valve disc 155 in the axial direction. Therefore, the opening-closing disc 152D comes into surface contact with the substrate disc 301D by its elastic force, and closes the multiple passage holes 163D.

[0179] The body valve 30D has a second passage 221D that is partially different from the second passage 221C in place of the second passage 221C. The second passage 221D has a variable chamber 220D that is partially different from the variable chamber 220C in place of the variable chamber 220C. The variable chamber 220D is formed by a portion surrounded by the base main body portion 82, inner seat 84, outer seat 88, disc 151, and valve disc 154 of the valve base 25C, the passage holes 172 and 181 of the valve discs 154 and 155, and a portion surrounded by the partition member 255D, the valve disc 155, and disc 291D.

[0180] The body valve 30D serves as a second damping disc valve 222D that opens and closes a second passage 221D by the valve discs 154, 155, 156C, 157 and the partition member 255D moving away from and contacting the outer seat 88. A flow of hydraulic fluid L, which is a working fluid, is generated in the second passage 221D by the movement of the piston 45 (see FIG. 1) in the compression direction. The second damping disc valve 222D applies resistance to the flow of hydraulic fluid L from the second chamber 49 (see FIG. 1) on the upstream side of the second passage 221D to the reservoir chamber 18 on the downstream side. The second damping disc valve 222D and a third passage 231, which is an orifice, are provided in the second passage 221D, and constitute a compression-side second damping force generation mechanism 225D that generates a damping force by suppressing the flow of hydraulic fluid L flowing in the second passage 221D.

[0181] A part of the variable chamber 220D of the second passage 221D and the third passage 231 are formed in the valve disc 154 seated on the outer seat 88 of the second damping disc valve 222D.

[0182] In the body valve 30D, the base main body portion 82, inner seat 84, outer seat 88 of the valve base 25C, valve discs 154, 155, 156C, partition member 255D, and discs 151, 291D, 292D constitute a pressure accumulating mechanism 251D including a variable chamber 220D.

[0183] In pressure accumulation mechanism 251D, the portion surrounded by valve disc 156C, partition member 255D, and disc 292D constitutes variable chamber 252D. Variable chamber 252D is partitioned from variable chamber 220D of second passage 221D by partition member 255D. Variable chamber 252D communicates with fourth passage 241C.

[0184] The partitioning member 255D moves in response to pressure changes in the upstream reservoir chamber 18 or the downstream second chamber 49 (see FIG. 2) when the piston 45 (see FIG. 1) moves in the extension direction. The partitioning member 255D moves in response to pressure changes in the upstream second chamber 49 (see FIG. 2) or the downstream reservoir chamber 18 when the piston 45 (see FIG. 1) moves in the contraction direction. The partitioning member 255D increases the size of the variable chamber 252D and decreases the size of the variable chamber 220D during the extension stroke of the piston 45 (see FIG. 1), while increasing the size of the variable chamber 220D and decreasing the size of the variable chamber 252D during the contraction stroke of the piston 45 (see FIG. 1).

[0185] When partitioning member 255D deforms in the direction of enlarging variable chamber 220D, once it has deformed a predetermined amount, substrate disk 301D of partitioning member main body 153D abuts against valve disk 156C, suppressing further deformation. Outer peripheral disk 302D of partitioning member 255D always abuts against valve disk 156C over the entire periphery.

[0186] The pressure accumulation mechanism 251D has a variable chamber 252D that communicates with the fourth passage 241C. The variable chamber 252D is separated from the variable chamber 220D of the second passage 221D by a partition member 255D that moves in response to a pressure change in the upstream reservoir chamber 18 or the downstream second chamber 49 (see FIG. 2) when the piston 45 (see FIG. 1) moves in the extension direction.

[0187] The variable chambers 220D, 252D are formed by the second damping disc valve 222D. The variable chamber 252D is disposed inside the second damping disc valve 222D. The variable chambers 220D, 252D are disposed on the second damping disc valve 222D so as to overlap with the second damping disc valve 222D in the axial direction. The pressure accumulation mechanism 251D including the variable chambers 220D, 252D is disposed on the second damping disc valve 222D so as to overlap with the second damping disc valve 222D in the axial direction.

[0188] The passage hole 163D of the partition member main body 153D and the opening / closing disc 152D constitute a relief mechanism 258D that relieves pressure within the variable chamber 252D after the differential pressure between the upstream variable chamber 252D and the downstream variable chamber 220D reaches a predetermined value when the piston 45 (see Figure 1) moves in the extension direction.

[0189] The hydraulic circuit diagram of the body valve 30D is similar to that of the body valve 30.

[0190] Next, the main operation of the body valve 30D will be described.

[0191] During the extension stroke, the pressure in the second chamber 49 (see FIG. 2) becomes lower than the pressure in the reservoir chamber 18, and the oil L in the reservoir chamber 18 is introduced into the first passage 211 and flows to the second chamber 49 (see FIG. 2) via the first damping force generating mechanism 215 (see FIG. 2). In addition, the oil L in the reservoir chamber 18 is introduced from the fourth passage 241C into the variable chamber 252D of the pressure accumulating mechanism 251D, deforming the partition member 255D and expanding the variable chamber 252D. At that time, the oil L in the contracted variable chamber 220D is discharged into the second chamber 49 (see FIG. 2) via the second passage 221D.

[0192] During the extension stroke when the piston speed is low and the piston frequency is low, the stroke of the piston 45 (see FIG. 1) is large. Therefore, in the early stage of introduction of hydraulic fluid L from the reservoir chamber 18 into the variable chamber 252D via the fourth passage 241C, the partition member 255D is significantly deflected, and further deformation is suppressed. As a result, the variable chamber 252D is placed in a state where an increase in volume is suppressed, and the variable chamber 252D is unable to absorb the increased amount of hydraulic fluid L being introduced. This increases the force with which the hydraulic fluid L in the reservoir chamber 18 pushes the first damping valve 212 (see FIG. 2) in the opening direction. This causes the first damping valve 212 (see FIG. 2) to open, allowing hydraulic fluid L to flow into the second chamber 49 (see FIG. 2) via the first passage 211. Therefore, during the extension stroke when the piston speed is low and the piston frequency is low, the damping force characteristics are the same as when there is no pressure accumulation mechanism 251D.

[0193] On the other hand, even when the piston speed is low and the piston frequency is high and equal to or greater than a predetermined value, the stroke of the piston 45 (see FIG. 1) is small during the extension stroke, and therefore the volume of hydraulic fluid L introduced from the reservoir chamber 18 into the variable chamber 252D via the fourth passage 241C is small. As a result, the partitioning member 255D also deflects only a small amount. As a result, most of the increase in hydraulic fluid L introduced from the reservoir chamber 18 into the variable chamber 252D via the fourth passage 241C is absorbed by the deflection of the partitioning member 255D. As a result, the force with which the hydraulic fluid L in the reservoir chamber 18 pushes the first damping valve 212 (see FIG. 2) in the opening direction is suppressed more than when the piston frequency is low and less than a predetermined value, and the damping force is lower and softer than at low frequencies.

[0194] Furthermore, during the extension stroke when the piston speed is high and equal to or greater than a predetermined value, the open-close disc 152D deforms and separates from the partition member main body 153D. In other words, the relief mechanism 258D opens. This allows the oil L in the variable chamber 252D to flow into the second chamber 49 (see FIG. 2) through the second passage 221D including the variable chamber 220D.

[0195] During the compression stroke, the pressure in the second chamber 49 (see FIG. 2) becomes higher than the pressure in the reservoir chamber 18, and the oil L in the second chamber 49 (see FIG. 2) is introduced into the second passage 221D and flows into the reservoir chamber 18 via the second damping force generating mechanism 225D. In addition, the oil L in the second chamber 49 (see FIG. 2) is introduced into the variable chamber 220D of the pressure accumulating mechanism 251D, deforming the partition member 255D and expanding the variable chamber 220D. At that time, the oil L in the contracting variable chamber 252D is discharged into the reservoir chamber 18 via the fourth passage 241C.

[0196] During a compression stroke when the piston frequency is lower than a predetermined value, the stroke of the piston 45 (see FIG. 1) is large. Therefore, in the early stage of introduction of hydraulic fluid L from the second chamber 49 (see FIG. 2) into the variable chamber 220D, the partition member 255D bends significantly and abuts against the valve disc 156C, suppressing further deformation. As a result, the volume of the variable chamber 220D remains unchanged, and the variable chamber 220D is no longer able to absorb the increased amount of hydraulic fluid L being introduced. This causes the pressure in the variable chamber 220D to rise to a high pressure, increasing the force pushing the second damping disc valve 222D in the opening direction. This causes the second damping disc valve 222D to open, allowing hydraulic fluid L to flow into the reservoir chamber 18 through the gap with the outer seat 88. Therefore, during a compression stroke when the piston frequency is low and lower than a predetermined value, the damping force characteristics are the same as when the pressure accumulation mechanism 251D is not present.

[0197] On the other hand, during the compression stroke when the piston frequency is equal to or greater than a predetermined value, the stroke of the piston 45 (see FIG. 1) is small, and therefore the volume of the oil L introduced from the second chamber 49 (see FIG. 2) into the variable chamber 220D is small, and the partition member 255D therefore deflects only a small amount and is easily deformed. As a result, most of the increase in the amount of oil L introduced from the second chamber 49 (see FIG. 2) into the variable chamber 220D is absorbed by the deflection of the partition member 255D. As a result, the pressure in the variable chamber 220D is low, and the valve opening pressure of the second damping disc valve 222D does not increase. Therefore, during the compression stroke, when the piston frequency is high, the damping force is lower and softer than when the piston frequency is low.

[0198] The shock absorber 11D and its body valve 30D of the fifth embodiment have the same effects as those of the first embodiment.

[0199] [Sixth embodiment] Next, the sixth embodiment will be described, focusing on the differences from the first embodiment, mainly with reference to Fig. 21. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0200] As shown in FIG. 21, a shock absorber 11E of the sixth embodiment has a body valve 30E which is partially different from the body valve 30 instead of the body valve 30.

[0201] The body valve 30E is provided with, on the axial leg portion 72 side of the base portion 71, in the following order from the axial base portion 71 side: one disc 311, one disc 312, one opening / closing disc 152E, one partition disc 314, one disc 315, one belleville spring 153E, one valve disc 154E, one valve disc 155 similar to the above, one valve disc 156 similar to the above, multiple valve discs, specifically three valve discs 157 similar to the above, one disc 158 similar to the above, and one disc 159 similar to the above.

[0202] The valve disc 154E differs from the valve disc 154 in that it has a passage hole 172E that is positioned differently from the passage hole 172 and is smaller than the passage hole 172.

[0203] The disks 311, 312, 315, the opening / closing disk 152E, the partition disk 314, and the Belleville spring 153E are all made of metal. The disks 311, 312, and 315 are all circular flat plates with holes of a certain thickness, into which the shaft portion 103 of the pin member 101 can be fitted. The opening / closing disk 152E, the Belleville spring 153E, and the partition disk 314 are all annular, into which the shaft portion 103 of the pin member 101 can be fitted.

[0204] The disk 311 has an outer diameter larger than the outer diameter of the inner seat 84 of the valve base 25 so as not to come into contact with the plurality of protrusions 89 . The disc 312 has an outer diameter equal to the outer diameter of the inner seat 84 of the valve base 25 and smaller than the outer diameter of the disc 311 .

[0205] In its natural state before being assembled into the body valve 30E, the open-close disc 152E is a perforated, flat circular plate of a certain thickness. The open-close disc 152E is flexible. The open-close disc 152E has an outer diameter larger than that of the disc 311, and is designed so as not to come into contact with the multiple protrusions 89 of the valve base 25.

[0206] The partition disc 314 is a perforated circular flat plate of a certain thickness in its natural state before being assembled into the body valve 30E. The partition disc 314 has an outer diameter larger than the outer diameter of the opening-closing disc 152E so that it can abut against the multiple protrusions 89. The partition disc 314 is flexible. The partition disc 314 has multiple passage holes 321 formed at equal intervals around the circumferential direction of the partition disc 314 at positions that are opened and closed by the opening-closing disc 152E. Disk 315 has an outer diameter equal to that of disk 312 .

[0207] The disc spring 153E is formed by press molding from a single flat plate material. The disc spring 153E has a base plate portion 161E and an outer peripheral tapered plate portion 162E. The disc spring 153E is flexible.

[0208] The substrate portion 161E is a circular flat plate with a certain thickness and has a hole. The substrate portion 161E has a passage hole 163E formed therein, which passes through the substrate portion 161E in the axial direction of the substrate portion 161E. The substrate portion 161E has a plurality of passage holes 163E formed therein at equal intervals in the circumferential direction of the substrate portion 161E.

[0209] The outer peripheral tapered plate portion 162E widens in a tapered shape from the outer peripheral edge of the substrate portion 161E. The outer peripheral tapered plate portion 162E increases in diameter as it moves away from the substrate portion 161E in the axial direction of the substrate portion 161E. The outer peripheral tapered plate portion 162E is annular and is formed around the entire circumference of the substrate portion 161E.

[0210] When assembling the body valve 30E, the pin member 101 is stacked on the head 102 in this order with the disc 159, disc 158, multiple valve discs 157, valve disc 156, valve disc 155, valve disc 154E, conical spring 153E, disc 315, partition disc 314, opening / closing disc 152E, disc 312, disc 311, and valve base 25, with the shaft portion 103 of the pin member 101 fitted inside each of them.

[0211] At this time, the conical spring 153E is oriented so that the outer peripheral tapered plate portion 162E extends axially away from the valve disc 154E. Also, at this time, the valve base 25 is oriented so that the inner seat 84 abuts against the disc 311.

[0212] When assembled into the body valve 30E, the disc 159, disc 158, the multiple valve discs 157, valve disc 156, valve disc 155, valve disc 154E, disc spring 153E, disc 315, partition disc 314, open / close disc 152E, disc 312, and disc 311 are clamped at least on their inner circumferential sides to the head 102 of the pin member 101 and the inner seat 84 of the valve base 25. At this time, the disc spring 153E has the inner circumferential side of the base plate portion 161E clamped to the disc 315 and the valve disc 154E.

[0213] When assembled into the body valve 30E, the base plate portion 161E of the conical spring 153E is in surface contact with the valve disc 154E, and the passage hole 163E communicates with the passage hole 172E.

[0214] When assembled into the body valve 30E, the partition disc 314 has a flat inner portion and an outer portion that abuts against the outer peripheral edge of the outer tapered plate portion 162E of the conical spring 153E, and is deformed in a tapered shape so that the radially outward portion moves away from the valve disc 154E in the axial direction.

[0215] When the open-close disc 152E is assembled into the body valve 30E, the inner peripheral portion thereof becomes flat, and the outer peripheral portion thereof deforms to conform to the partition disc 314 and comes into surface contact with the partition disc 314 by its elastic force. At this time, the open-close disc 152E entirely covers the plurality of passage holes 321 of the partition disc 314, thereby closing the plurality of passage holes 321.

[0216] The body valve 30E has a second passage 221E that is partially different from the second passage 221 instead of the second passage 221. The second passage 221E includes a variable chamber 220E that is surrounded by the base main body portion 82, inner seat 84, outer seat 88, and multiple protrusions 89 of the valve base 25, the discs 311 and 312, the open-close disc 152E, the partition disc 314, the conical spring 153E, and the valve disc 154E. The second passage 221E includes a third passage 231 that is an orifice in the notch 171 of the valve disc 154E. The third passage 231 constantly connects the variable chamber 220E and the reservoir chamber 18.

[0217] The body valve 30E is a second damping disc valve 222E that opens and closes a second passage 221E by the valve discs 154E, 155-157 moving away from and contacting the outer seat 88. In the second passage 221E, a flow of hydraulic fluid L, which is a working fluid, is generated by the movement of the piston 45 (see FIG. 1) in the contraction direction. The second damping disc valve 222E applies resistance to the flow of hydraulic fluid L from the second chamber 49 (see FIG. 2) on the upstream side of the second passage 221E to the reservoir chamber 18 on the downstream side.

[0218] A second damping disc valve 222E and a third passage 231, which is an orifice, are provided in the second passage 221E, and constitute a second damping force generating mechanism 225E on the compression side that generates a damping force by suppressing the flow of oil liquid L flowing through the second passage 221E.

[0219] In the body valve 30E, the notch 191 and the passage hole 192 of the valve disc 156 of the second damping disc valve 222E, the passage hole 181 of the valve disc 155, and the passage hole 172E of the valve disc 154E form a fourth passage 241E (communicating passage) that is always in communication with the upstream reservoir chamber 18 when the piston 45 (see Figure 1) moves in the extension direction.

[0220] In the fourth passage 241E, the inside of the notch 191 of the valve disc 156 forms an orifice 242. In the fourth passage 241E, the inside of the passage hole 192 of the valve disc 156, the inside of the passage hole 181 of the valve disc 155, and the inside of the passage hole 172E of the valve disc 154E form an intermediate chamber 243E.

[0221] The third passage 231 and a portion of the fourth passage 241E are formed in a valve disc 154E that is seated on the outer seat 88 of the second damping disc valve 222E.

[0222] The body valve 30E includes a base main body portion 82 of the valve base 25, an inner seat 84, an outer seat 88 and a plurality of protrusions 89, discs 311, 312, 315, an opening / closing disc 152E, a partition disc 314, a conical spring 153E and a valve disc 154E, which together form a pressure accumulation mechanism 251E including a variable chamber 220E.

[0223] In the pressure accumulation mechanism 251E, the portion surrounded by the open-close disc 152E, the partition disc 314, the disc spring 153E, and the disc 315 constitutes a variable chamber 252E. The variable chamber 252E is partitioned from the variable chamber 220E of the second passage 221E by the disc spring 153E, the partition disc 314, and the open-close disc 152E. The disc spring 153E, the partition disc 314, and the open-close disc 152E constitute a partition member 255E that partitions the variable chamber 252E and the variable chamber 220E. The variable chamber 252E communicates with the fourth passage 241E.

[0224] The partitioning member 255E moves in response to pressure changes in the upstream reservoir chamber 18 or the downstream second chamber 49 (see FIG. 2) when the piston 45 (see FIG. 1) moves in the extension direction. The partitioning member 255E moves in response to pressure changes in the upstream second chamber 49 (see FIG. 2) or the downstream reservoir chamber 18 when the piston 45 (see FIG. 1) moves in the contraction direction. The partitioning member 255E is made up of a Belleville spring 153E. During the extension stroke of the piston 45 (see FIG. 1), the partitioning member 255E increases the size of the variable chamber 252E and decreases the size of the variable chamber 220E, while during the contraction stroke of the piston 45 (see FIG. 1), the partitioning member 255E increases the size of the variable chamber 220E and decreases the size of the variable chamber 252E.

[0225] When the partitioning member 255E deforms in a direction to increase the size of the variable chamber 252E, once it has deformed a predetermined amount, the partitioning disc 314 comes into contact with the protrusion 89 of the valve base 25, thereby suppressing further deformation. At this time, the outer peripheral tapered plate portion 162E of the disc spring 153E comes into contact with the partitioning disc 314 over the entire circumference, thereby sealing between the variable chamber 252E and the variable chamber 220E. When the partitioning member 255E deforms in a direction to increase the size of the variable chamber 220E, once it has deformed a predetermined amount, the valve disc 154E suppresses further deformation. At this time, the outer peripheral tapered plate portion 162E of the disc spring 153E also comes into contact with the valve disc 154E over the entire circumference, thereby sealing between the variable chamber 252E and the variable chamber 220E.

[0226] When the differential pressure between the upstream variable chamber 252E and the downstream variable chamber 220E reaches a predetermined value during movement of the piston 45 (see FIG. 1) in the extension direction, the opening-closing disc 152E separates from the partition disc 314, opening the passage hole 321 of the partition disc 314 and connecting the variable chamber 252E to the variable chamber 220E. The passage hole 321 of the partition disc 314 and the opening-closing disc 152E constitute a relief mechanism 258E that relieves the inside of the variable chamber 252E after the differential pressure between the upstream variable chamber 252E and the downstream variable chamber 220E during movement of the piston 45 (see FIG. 1) in the extension direction reaches a predetermined value.

[0227] When the differential pressure between the upstream variable chamber 252E and the downstream variable chamber 220E reaches a predetermined value during movement of the piston 45 (see FIG. 1) in the extension direction, the outer peripheral tapered plate portion 162E of the disc spring 153E separates from the open-close disc 152E, thereby connecting the variable chamber 252E to the variable chamber 220E. The outer peripheral tapered plate portion 162E of the disc spring 153E and the partition disc 314 constitute a relief mechanism 331 that relieves the inside of the variable chamber 252E after the differential pressure between the upstream variable chamber 252E and the downstream variable chamber 220E during movement of the piston 45 (see FIG. 1) in the extension direction reaches a predetermined value. In other words, the partition member 255E is provided with the relief mechanisms 258E, 331.

[0228] The pressure accumulation mechanism 251E has a variable chamber 252E that communicates with the fourth passage 241E. The variable chamber 252E is separated from the variable chamber 220E of the second passage 221E by a partition member 255E that moves in response to a pressure change in the upstream reservoir chamber 18 or the downstream second chamber 49 (see FIG. 2) when the piston 45 (see FIG. 1) moves in the extension direction.

[0229] The variable chambers 220E, 252E are arranged to overlap the second damping disc valve 222E in the axial direction of the second damping disc valve 222E. The pressure accumulation mechanism 251E including the variable chambers 220E, 252E is arranged to overlap the second damping disc valve 222E in the axial direction of the second damping disc valve 222E.

[0230] The hydraulic circuit diagram of the body valve 30E described above is the same as that of the body valve 30.

[0231] Next, the main operation of the body valve 30E will be described.

[0232] During the extension stroke, the pressure in the second chamber 49 (see FIG. 2) becomes lower than the pressure in the reservoir chamber 18, and the oil L in the reservoir chamber 18 is introduced into the first passage 211 and flows to the second chamber 49 (see FIG. 2) via the first damping force generating mechanism 215 (see FIG. 2). In addition, the oil L in the reservoir chamber 18 is introduced from the fourth passage 241E into the variable chamber 252E of the pressure accumulating mechanism 251E, deforming the partition member 255E and expanding the variable chamber 252E. At that time, the oil L in the contracted variable chamber 220E is discharged into the second chamber 49 (see FIG. 2) via the second passage 221E.

[0233] During the extension stroke when the piston speed is low and the piston frequency is low, the stroke of the piston 45 (see FIG. 1) is large. Therefore, in the early stage of introduction of hydraulic fluid L from the reservoir chamber 18 into the variable chamber 252E through the fourth passage 241E, the partition member 255E is significantly deflected, causing the partition disc 314 to abut against the protrusion 89 of the valve base 25, suppressing further deformation. At this time, the conical spring 153E maintains contact with the outer peripheral tapered plate portion 162E. As a result, the variable chamber 252E is suppressed from increasing in volume, and is unable to absorb the increased amount of hydraulic fluid L being introduced. This increases the force of the hydraulic fluid L in the reservoir chamber 18 pushing the first damping valve 212 in the opening direction. This causes the first damping valve 212 to open, allowing hydraulic fluid L to flow through the first passage 211 into the second chamber 49 (see FIG. 2). Therefore, during the extension stroke when the piston speed is low and the piston frequency is low, the damping force characteristics are the same as when there is no pressure accumulation mechanism 251E.

[0234] On the other hand, even when the piston speed is low (below a predetermined value), the stroke of the piston 45 (see FIG. 1) is small during the extension stroke when the piston frequency is high (above a predetermined value), and therefore the volume of hydraulic fluid L introduced from the reservoir chamber 18 into the variable chamber 252E via the fourth passage 241E is small. Therefore, the deflection of the partition disc 314 is small, and the partition disc 314 does not contact the protrusion 89 of the valve base 25, or is deformable even if it does contact the protrusion 89. Even in this case, the conical spring 153E maintains contact with the outer peripheral tapered plate portion 162E. Therefore, the deflection of the partition disc 314 absorbs most of the increase in hydraulic fluid L introduced from the reservoir chamber 18 into the variable chamber 252E via the fourth passage 241E. This reduces the force with which the hydraulic fluid L in the reservoir chamber 18 pushes the first damping valve 212 in the opening direction compared to when the piston frequency is low (below a predetermined value), resulting in a softer damping force than at low frequencies.

[0235] Furthermore, when the piston speed is high, equal to or greater than a predetermined value, the partition disc 314 bends significantly and abuts against the protrusion 89 of the valve base 25, suppressing further deformation, and the open-close disc 152E deforms and moves away from the partition disc 314. In other words, the relief mechanism 258E opens. At the same time, the outer peripheral tapered plate portion 162E of the disc spring 153E deforms and moves away from the partition disc 314. In other words, the relief mechanism 331 opens. As a result, the oil L in the variable chamber 252E flows into the second chamber 49 (see FIG. 2) through the second passage 221E including the variable chamber 220E. Note that, during the above-mentioned deformation, the open-close disc 152E abuts against the disc 311, suppressing further deformation.

[0236] During the compression stroke, the pressure in the second chamber 49 (see FIG. 2) becomes higher than the pressure in the reservoir chamber 18, and the oil L in the second chamber 49 (see FIG. 2) is introduced into the second passage 221E and flows into the reservoir chamber 18 via the second damping force generating mechanism 225. In addition, the oil L in the second chamber 49 (see FIG. 2) is introduced into the variable chamber 220E of the pressure accumulating mechanism 251E, deforming the partition member 255E and expanding the variable chamber 220E. At that time, the oil L in the contracting variable chamber 252E is discharged into the reservoir chamber 18 via the fourth passage 241E.

[0237] During the compression stroke when the piston frequency is lower than a predetermined value, the stroke of the piston 45 (see FIG. 1) is large. Therefore, at the beginning of the introduction of hydraulic fluid L from the second chamber 49 (see FIG. 2) into the variable chamber 220E, the partition member 255E is significantly deflected, causing the outer peripheral tapered plate portion 162E of the coned disc spring 153E to abut against the valve disc 154E, suppressing further deformation. As a result, the volume of the variable chamber 220E remains unchanged, and the variable chamber 220E is no longer able to absorb the increased amount of hydraulic fluid L being introduced. This causes the pressure in the variable chamber 220E to rise to a high pressure, increasing the force pushing the second damping disc valve 222E in the opening direction. As a result, the second damping disc valve 222E opens, allowing hydraulic fluid L to flow into the reservoir chamber 18 through the gap with the outer seat 88. Therefore, during the compression stroke when the piston frequency is low and lower than a predetermined value, the damping force characteristics are the same as when the pressure accumulation mechanism 251E is not present.

[0238] On the other hand, during the compression stroke when the piston frequency is equal to or greater than a predetermined value, the stroke of the piston 45 (see FIG. 1) is small, and therefore the volume of the oil L introduced from the second chamber 49 (see FIG. 2) into the variable chamber 220E is small, and the partition disc 314 is easily deformed with a small amount of deflection. As a result, most of the increase in the amount of oil L introduced from the second chamber 49 (see FIG. 2) into the variable chamber 220E is absorbed by the deflection of the partition member 255E. As a result, the variable chamber 220E is at low pressure, and the opening pressure of the second damping disc valve 222E does not increase. Therefore, when the piston frequency is high, the damping force is lower and softer than when the piston frequency is low.

[0239] The shock absorber 11E and its body valve 30E of the sixth embodiment have the same effects as those of the first embodiment.

[0240] The structures of the first to sixth embodiments can be applied to various structures as long as they include a first passage through which the flow of working fluid occurs when the piston moves in one direction, a second passage through which the flow of working fluid occurs when the piston moves in the other direction, a first damping valve that opens and closes the first passage, and a second damping disc valve that opens and closes the second passage. That is, the first to sixth embodiments have been described using an example in which the second damping disc valves 222, 222A-222E and the pressure accumulator mechanisms 251, 251A-251E are arranged in a stacked manner on the reservoir chamber 18 side of the body valves 30, 30A-30E. However, for example, the second damping disc valves 222, 222A-222E and the pressure accumulator mechanisms 251, 251A-251E may be arranged in a stacked manner on the second chamber 49 side of the body valve. The structures of the first to sixth embodiments can also be applied to the piston 45 (see FIG. 1). In this case, the second damping disc valves 222, 222A to 222E and the pressure accumulation mechanisms 251, 251A to 251E may be arranged in a stacked manner on the first chamber 48 side of the piston 45, or the second damping disc valves 222, 222A to 222E and the pressure accumulation mechanisms 251, 251A to 251E may be arranged in a stacked manner on the second chamber 49 side of the piston 45. [Industrial Applicability]

[0241] According to the above aspects of the present invention, it is possible to provide a shock absorber and a damping valve device that can suppress the generation of abnormal noise, and thus the industrial applicability is great. [Explanation of symbols]

[0242] 11, 11A to 11E... shock absorber, 17... cylinder, 18... reservoir chamber, 30, 30A to 30E... body valve (damping valve device), 45... piston, 49... second chamber, 88... outer seat (seat), 153, 153E... conical spring, 154, 154E... valve disc, 211... first passage, 212... first damping valve, 220, 220A to 220E... variable chamber, 22 1, 221A to 221E...second passage, 222, 222C to 222E...second damping disc valve, 231...third passage, 241, 241C, 241E...fourth passage (communicating passage), 251, 251A to 251E...pressure accumulation mechanism, 252, 252A to 252E...variable chamber, 255, 55A to 255E...partition member, 258, 258B, 258D, 258E, 331...relief mechanism.

Claims

1. a cylinder in which a working fluid is sealed; a piston fitted in the cylinder to partition the interior of the cylinder; a first passage and a second passage through which the flow of the working fluid occurs due to the movement of the piston; a first damping valve that applies resistance to the flow of the hydraulic fluid from the upstream chamber to the downstream chamber of the first passage by unidirectional movement of the piston; a second damping disc valve that resists the flow of the hydraulic fluid from the upstream chamber to the downstream chamber of the second passage in response to the movement of the piston in the other direction; an orifice that restricts the flow of the working fluid in the second passage; a partition member in which a radially inner side and a radially outer side of the second damping disc valve abut against each other, forming a variable chamber between the second damping disc valve and the partition member, and which operates to change the volume of the variable chamber by moving in response to a pressure difference between an upstream chamber and a downstream chamber of the variable chamber; have buffer.

2. 2. The shock absorber according to claim 1, wherein the orifice is formed in the second damping disc valve.

3. The partition member is formed of a disc spring, 3. The shock absorber according to claim 2, wherein the volume of the variable chamber formed between the piston and the second damping disc valve is increased during an extension stroke, which is the movement of the piston in the other direction, and the volume of the variable chamber is reduced during a compression stroke, which is the movement of the piston in one direction.

4. 4. The shock absorber according to claim 1, further comprising a relief mechanism that operates to allow the working fluid to flow in the variable chamber after the pressure in the variable chamber reaches a predetermined value.

5. 2. The shock absorber according to claim 1, wherein the second damping disc valve is provided in a body valve.

6. 3. The shock absorber according to claim 2, wherein the second damping disc valve is provided in a body valve.

7. 4. The shock absorber according to claim 3, wherein the second damping disc valve is provided in a body valve.

8. 5. The shock absorber according to claim 4, wherein the second damping disc valve is provided in a body valve.

9. A damping valve device that is connected to a cylinder in which a working fluid is sealed, a first passage and a second passage through which the flow of the working fluid occurs due to the movement of the piston in the cylinder; a first damping valve that applies resistance to the flow of the hydraulic fluid from the upstream chamber to the downstream chamber of the first passage by unidirectional movement of the piston; a second damping disc valve that resists the flow of the hydraulic fluid from the upstream chamber to the downstream chamber of the second passage in response to the movement of the piston in the other direction; an orifice that restricts the flow of the working fluid in the second passage; a partition member in which a radially inner side and a radially outer side of the second damping disc valve abut against each other, forming a variable chamber between the second damping disc valve and the partition member, and which operates to change the volume of the variable chamber by moving in response to a pressure difference between an upstream chamber and a downstream chamber of the variable chamber; have Damping valve device.

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