buffer

Abstract

The valve seat member (106) is provided in the cap member (101). The first sub valve (181) is provided in the other side chamber (20). The second sub valve (171) is provided in the cap chamber (146) between the bottom (122) of the cap member (101) and the valve seat member (106). In the second passage (182), a throttle portion (175) is arranged on the upstream side or the downstream side of the flow in which the first sub valve (181) is opened. In a region in which the piston speed is low, the second damping force generating mechanism (183) is opened in a state in which the first damping force generating mechanism (41) is closed. In a speed region in which the piston speed is higher than the low speed, both the first damping force generating mechanism (41) and the second damping force generating mechanism (183) are opened.

Description

Technical Field

[0001] This invention relates to buffers.

[0002] This application claims priority based on Japanese Patent Application No. 2018-241206, filed on December 25, 2018, the contents of which are incorporated herein by reference. Background Technology

[0003] The buffer has two valves arranged side by side that open during the same stroke (see, for example, Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2-41666 Summary of the Invention

[0007] The problem that the invention will solve

[0008] By arranging valves that open in parallel during the same stroke, it is possible to open only one valve in regions with low piston speeds, and open both valves in regions with higher piston speeds. In this configuration, it is particularly important to improve the durability of the valve on the low-speed side.

[0009] This invention provides a damper that can improve the durability of a valve.

[0010] Methods for solving problems

[0011] According to one aspect of the invention, the buffer includes: a piston slidably disposed in a cylinder dividing the cylinder into a side chamber and a side chamber; a first passage and a second passage for working fluid to flow from the upstream chamber to the downstream chamber within the cylinder by movement of the piston; a first damping force generating mechanism disposed in the first passage disposed on the piston, generating a damping force; and a second damping force generating mechanism disposed in an annular valve seat member disposed in the other side chamber, and in the second passage parallel to the first passage, generating a damping force. The second damping force generating mechanism includes: a first auxiliary valve disposed on one side of the second passage disposed on the valve seat member and a second auxiliary valve disposed on the other side; and a bottomed cylindrical cap member disposed between the piston and the valve seat member in the second passage. The valve seat member is disposed within the cap member. The first auxiliary valve is disposed in the other side chamber. The second auxiliary valve is disposed within the cap chamber between the bottom of the cap member and the valve seat member. In the second passage, a throttling section is provided upstream or downstream of the flow where the first auxiliary valve is open. In the region where the piston speed is low, the second damping force generating mechanism is open when the first damping force generating mechanism is closed. In the speed region where the piston speed is greater than the low speed, both the first and second damping force generating mechanisms are open.

[0012] Invention Effects

[0013] The aforementioned buffer can improve the durability of the valve. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view showing the buffer according to the first embodiment of the present invention.

[0015] Figure 2 This is a partial cross-sectional view showing the periphery of the piston of the buffer according to the first embodiment of the present invention.

[0016] Figure 3 This is a partial cross-sectional view showing the periphery of the throttling section of the buffer according to the first embodiment of the present invention.

[0017] Figure 4 This is a hydraulic circuit diagram of the buffer according to the first embodiment of the present invention.

[0018] Figure 5 This is a characteristic curve diagram showing the damping force characteristics during the extension stroke of the buffer according to the first embodiment of the present invention.

[0019] Figure 6 This is a cross-sectional view showing the main part of the buffer according to the second embodiment of the present invention.

[0020] Figure 7This is a cross-sectional view showing the main part of the buffer according to the third embodiment of the present invention.

[0021] Figure 8 This is a cross-sectional view showing the main part of the buffer according to the fourth embodiment of the present invention.

[0022] Figure 9 This is a cross-sectional view showing the main part of the buffer according to the fifth embodiment of the present invention.

[0023] Figure 10 This is a partial cross-sectional view showing the periphery of the throttling section of the buffer according to the fifth embodiment of the present invention.

[0024] Figure 11 This is a cross-sectional view showing the main part of the buffer according to the sixth embodiment of the present invention.

[0025] Figure 12 This is a partial cross-sectional view showing the periphery of the throttling section of the buffer according to the sixth embodiment of the present invention.

[0026] Figure 13 This is a cross-sectional view showing the main part of the buffer according to the seventh embodiment of the present invention.

[0027] Figure 14 This is a cross-sectional view showing the main part of the buffer according to the eighth embodiment of the present invention.

[0028] Figure 15 This is a cross-sectional view showing the main part of the buffer according to the ninth embodiment of the present invention. Detailed Implementation

[0029] [First Implementation Method]

[0030] based on Figures 1-5 The first embodiment of the present invention will be described. Furthermore, for ease of explanation, the upper side in the accompanying drawings will be referred to as "upper" and the lower side as "lower".

[0031] like Figure 1 As shown, the buffer 1 of the first embodiment is a so-called multi-cylinder type hydraulic buffer. The buffer 1 includes a cylinder 2 containing oil (not shown) as a working fluid. The cylinder 2 has a cylindrical inner cylinder 3 and a bottomed cylindrical outer cylinder 4 with a larger diameter than the inner cylinder 3 and arranged concentrically to cover the inner cylinder 3. A reservoir 6 is formed between the inner cylinder 3 and the outer cylinder 4.

[0032] The outer cylinder 4 includes a cylindrical main component 11 and a bottom component 12 that is fitted and fixed to the lower side of the main component 11 and seals the lower part of the main component 11. A mounting ring 13 is fixed to the bottom component 12 at an outer position opposite to that of the main component 11.

[0033] The buffer 1 includes a piston 18 slidably disposed inside the inner cylinder 3 of the cylinder body 2. This piston 18 divides the inner cylinder 3 into two chambers: an upper chamber 19 (one side chamber) and a lower chamber 20 (the other side chamber). In other words, the piston 18 slidably disposed within the cylinder body 2, dividing the cylinder body 2 into an upper chamber 19 and a lower chamber 20. Oil, serving as the working fluid, is sealed within the upper chamber 19 and lower chamber 20 inside the inner cylinder 3. A reservoir 6 between the inner cylinder 3 and the outer cylinder 4 contains both oil and gas, also serving as the working fluid.

[0034] The buffer 1 includes a piston rod 21, which is axially disposed at one end inside the inner cylinder 3 of the cylinder body 2 and connected to the piston 18, while the other end extends outward from the cylinder body 2. The piston rod 21 passes through the upper chamber 19 but not the lower chamber 20. Thus, the upper chamber 19 is the rod-side chamber through which the piston rod 21 passes, and the lower chamber 20 is the bottom-side chamber on the bottom side of the cylinder body 2.

[0035] The piston 18 and piston rod 21 move as a unit. During the extension stroke of the damper 1, when the piston rod 21 protrudes more from the cylinder 2, the piston 18 moves towards the upper chamber 19. During the compression stroke of the damper 1, when the piston rod 21 protrudes less from the cylinder 2, the piston 18 moves towards the lower chamber 20.

[0036] Rod guides 22 are fitted into the upper openings of the inner cylinder 3 and the outer cylinder 4. A sealing member 23 is fitted into the outer cylinder 4 on the outer side of the cylinder 2, near the rod guides 22. Both the rod guides 22 and the sealing member 23 are annular. The piston rod 21 is slidably inserted through the inner sides of the rod guides 22 and the sealing member 23, extending outward from the inside of the cylinder 2. One axial end of the piston rod 21 is fixed to the piston 18 inside the cylinder 2, while the other end protrudes outward from the cylinder 2 via the rod guides 22 and the sealing member 23.

[0037] The rod guide 22 supports the piston rod 21, restricting its radial movement while allowing it to move axially, and guides the movement of the piston rod 21. The sealing member 23 is in close contact with the outer cylinder 4 at its outer periphery and slides in contact with the outer periphery of the axially moving piston rod 21 at its inner periphery. Thus, the sealing member 23 prevents leakage of oil from the inner cylinder 3 and high-pressure gas and oil from the reservoir 6 in the outer cylinder 4 to the outside.

[0038] The outer periphery of the rod guide 22 is stepped, with the upper diameter larger than the lower diameter. The lower portion of the rod guide 22 is fitted into the inner periphery of the upper end of the inner cylinder 3, and the upper portion of the rod guide 22 is fitted into the inner periphery of the upper part of the outer cylinder 4. A base valve 25 dividing the lower chamber 20 and the liquid storage chamber 6 is provided on the bottom part 12 of the outer cylinder 4. The inner periphery of the lower end of the inner cylinder 3 is fitted into this base valve 25. The upper end of the outer cylinder 4 is riveted radially inward to form a locking part 26. This locking part 26 and the rod guide 22 clamp the sealing part 23.

[0039] The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28 with a smaller diameter. The main shaft portion 27 of the piston rod 21 is slidably fitted into the rod guide 22 and the sealing member 23, and the mounting shaft portion 28 is disposed within the cylinder body 2 and connected to the piston 18, etc. The end of the main shaft portion 27 on the mounting shaft portion 28 side becomes a shaft step portion 29 that extends in the direction orthogonal to the axis. On the outer periphery of the mounting shaft portion 28, a pair of axially extending passage notches 30 are formed at the middle position in the axial direction, and an external thread 31 is formed at the front end position on the side opposite to the main shaft portion 27 in the axial direction. The passage notches 30 are in the shape of two-sided width, formed by cutting the mounting shaft portion 28 circumferentially at two different positions of 180 degrees in a planar parallel cut.

[0040] Regarding the damper 1, for example, the piston rod 21 is positioned at the top of the cylinder body 2 and supported by the vehicle body, while the mounting ring 13 on the side of the cylinder body 2 is positioned at the bottom and connected to the wheel side. Alternatively, the cylinder body 2 can be supported by the vehicle body, and the piston rod 21 can be connected to the wheel side.

[0041] like Figure 2 As shown, the piston 18 includes a metal piston body 35 connected to the piston rod 21, and an annular synthetic resin sliding component 36 integrally mounted on the outer peripheral surface of the piston body 35 and sliding within the inner cylinder 3.

[0042] The piston body 35 is provided with a plurality of (in) ...xlear cavity 19 and lower chamber 20 that enable communication between the upper chamber 19 and the lower chamber 20. Figure 2 (Due to the cross-sectional shape, only one passage hole 37 is shown in the diagram, and multiple passage holes that allow the upper chamber 19 to connect with the lower chamber 20 are also shown.) Figure 2 (Due to the cross-sectional view, only one passage hole 39 is shown in the diagram.) The piston body 35 is a sintered product, and the passage holes 37 and 39 are formed during sintering. Alternatively, they can be formed by cutting with a drill bit.

[0043] In the circumferential direction of the piston body 35, a plurality of through holes 37 are formed at equal intervals, each separated by a through hole 39, constituting half of the through holes 37 and 39. The plurality of through holes 37 have a crank shape with two inflection points. The axial side of the piston 18 with the plurality of through holes 37 ( Figure 2The upper side) opens radially outward to the piston 18, and the axial side of the piston 18 (the other side) Figure 2 The lower side of the piston 18 opens radially inwards towards the inner side of the piston 18.

[0044] A first damping force generating mechanism 41 is provided on the lower chamber 20 side of these passage holes 37 to generate damping force by opening and closing the passages within the passage holes 37. The first damping force generating mechanism 41 is disposed on the lower chamber 20 side such that the passages within the plurality of passage holes 37 are extension-side passages such that when the piston 18 moves towards the upper chamber 19, in other words, during the extension stroke, oil flows from the upper chamber 19, which is the upstream side, towards the lower chamber 20, which is the downstream side. The first damping force generating mechanism 41 provided for the passages within these passage holes 37 is an extension-side damping force generating mechanism that generates damping force by suppressing the flow of oil from the passages within the extension-side passage holes 37 to the lower chamber 20.

[0045] The remaining half of the passage holes 37 and 39 are formed at equal intervals in the circumferential direction of the piston body 35, with a passage hole 37 spaced apart from each other.

[0046] The multiple through-holes 39 have a crank shape with two inflection points. The piston 18 with the multiple through-holes 39 is on the other side of the axial direction ( Figure 2 The lower side) has an opening on the outer side of the piston 18 in the radial direction, and the piston 18 has an opening on one side in the axial direction ( Figure 2 The upper side of the piston 18 has an inner opening in the radial direction compared to the other side.

[0047] A first damping force generating mechanism 42 is provided on the upper chamber 19 side of these passage holes 39 to generate damping force by opening and closing the passages within the passage holes 39. The first damping force generating mechanism 42 is disposed on the upper chamber 19 side such that the passages within the plurality of passage holes 39 become compression-side passages: when the piston 18 moves towards the lower chamber 20, in other words, during the compression stroke, oil flows from the lower chamber 20, which is the upstream side, towards the upper chamber 19, which is the downstream side. The first damping force generating mechanism 42 provided for the passages within these passage holes 39 becomes a compression-side damping force generating mechanism that generates damping force by suppressing the flow of oil from the passages within the compression-side passage holes 39 to the upper chamber 19.

[0048] The piston body 35 is generally circular. An insertion hole 44 is formed axially through the center of the piston body 35 for inserting the mounting shaft portion 28 of the piston rod 21. The insertion hole 44 has a small-diameter bore portion 45 on one axial side for engaging the mounting shaft portion 28 of the piston rod 21, and a large-diameter bore portion 46 on the other axial side, which is larger than the small-diameter bore portion 45.

[0049] At the axial end of the piston body 35 on the lower chamber 20 side, an annular inner seat portion 47 is formed on the radially inner side of the opening on the lower chamber 20 side of the passage hole 37. At the axial end of the piston body 35 on the lower chamber 20 side, an annular valve seat portion 48, constituting part of the first damping force generating mechanism 41, is formed on the radially outer side of the opening on the lower chamber 20 side of the passage hole 37.

[0050] At the end of the piston body 35 on the axial side of the upper chamber 19, an annular inner seat portion 49 is formed on the radially inner side of the opening on the upper chamber 19 side of the passage hole 39. At the end of the piston body 35 on the axial side of the upper chamber 19, an annular valve seat portion 50, constituting part of the first damping force generating mechanism 42, is formed on the radially outer side of the opening on the upper chamber 19 side of the passage hole 39.

[0051] The large-diameter bore 46 of the piston body 35 is located on the inner side of the seat 47, which is axially closer than the small-diameter bore 45. The passage in the large-diameter bore 46 of the piston body 35 is always connected to the passage in the passage notch 30 of the piston rod 21.

[0052] In the piston body 35, there is a step-shaped section radially outward from the valve seat portion 48, with a lower axial height than the valve seat portion 48. An opening for the lower chamber 20 side of the compression-side passage hole 39 is provided in this stepped portion. Similarly, in the piston body 35, there is a step-shaped section radially outward from the valve seat portion 50, with a lower axial height than the valve seat portion 50. An opening for the upper chamber 19 side of the extension-side passage hole 37 is provided in this stepped portion.

[0053] The first damping force generating mechanism 42 on the compression side includes a valve seat portion 50 of the piston 18, and sequentially includes, from the axial piston 18 side, a disk 62, a plurality of disks 63 with the same inner diameter and the same outer diameter (specifically four), a plurality of disks 64 with the same inner diameter and the same outer diameter (specifically two), a disk 65, a disk 66, and an annular member 67. The disks 62-66 and the annular member 67 are made of metal. The disks 62-66 and the annular member 67 are all perforated circular flat plates of a certain thickness capable of fitting the mounting shaft portion 28 of the piston rod 21 internally.

[0054] The disc 62 has an outer diameter that is larger than the outer diameter of the inner seat portion 49 of the piston 18 and smaller than the inner diameter of the valve seat portion 50. The disc 62 always abuts against the inner seat portion 49. A plurality of discs 63 have an outer diameter that is approximately equal to the outer diameter of the valve seat portion 50 of the piston 18. The plurality of discs 63 can be seated on the valve seat portion 50.

[0055] Multiple discs 64 have an outer diameter smaller than that of disc 63. Disc 65 has an outer diameter smaller than that of disc 64 and smaller than that of the inner seat portion 49 of piston 18. Disc 66 has an outer diameter larger than that of disc 64 and smaller than that of disc 63. An annular member 67 has an outer diameter smaller than that of disc 66 and larger than that of the shaft step portion 29 of piston rod 21. The annular member 67 is thicker and more rigid than discs 62-66. The annular member 67 abuts against the shaft step portion 29.

[0056] Multiple discs 63 and multiple discs 64 constitute a main valve 71 on the compression side, which can be disengaged from and seated relative to the valve seat portion 50. The main valve 71, by disengaging from the valve seat portion 50, connects the passage in the passage hole 39 to the upper chamber 19 and generates a damping force by suppressing the flow of oil between itself and the valve seat portion 50. The annular member 67, together with the discs 66, restricts the deformation of the main valve 71 in the opening direction by a predetermined amount.

[0057] The passage between the main valve 71 and the valve seat portion 50, which appears when the valve is opened, and the passage within the passage hole 39, constitute a first passage 72 on the compression side, through which oil flows from the lower chamber 20 (upstream side) to the upper chamber 19 (downstream side) within the cylinder 2, caused by the movement of the piston 18. A first damping force generating mechanism 42 on the compression side, which generates damping force, includes the main valve 71 and the valve seat portion 50. Thus, the first damping force generating mechanism 42 is provided in this first passage 72. The first passage 72 is provided in the piston 18, which includes the valve seat portion 50, and supplies oil through it when the piston rod 21 and the piston 18 move towards the compression side.

[0058] In the first damping force generating mechanism 42 on the compression side, neither the valve seat portion 50 nor the main valve 71 abutting therewith has a fixed throttling section that connects the upper chamber 19 and the lower chamber 20 even when they are in contact. That is, if the valve seat portion 50 and the main valve 71 are in contact throughout their entire circumference, the first damping force generating mechanism 42 on the compression side will not connect the upper chamber 19 and the lower chamber 20. In other words, the first passage 72 does not have a fixed throttling section that always connects the upper chamber 19 and the lower chamber 20, and is not a passage that always connects the upper chamber 19 and the lower chamber 20.

[0059] The first damping force generating mechanism 41 on the elongated side includes a valve seat portion 48 of the piston 18, and sequentially includes a disc 82, multiple (specifically five) discs 83 with the same inner diameter and the same outer diameter, a disc 84, and a disc 85 from the axial piston 18 side. Discs 82 to 85 are made of metal. Discs 82 to 85 are all perforated circular flat plates of a certain thickness that can be fitted inside the mounting shaft portion 28 of the piston rod 21.

[0060] The disc 82 has an outer diameter that is larger than the outer diameter of the inner seat 47 of the piston 18 and smaller than the inner diameter of the valve seat 48. The disc 82 always abuts against the inner seat 47. Figure 3 As shown, on the disc 82, the passage in the passage hole 37 is always connected to the passage in the large diameter hole 46 of the piston 18 and the passage in the passage notch 30 of the piston rod 21. The notch 88 is formed from the middle position of the radial outer peripheral side to the inner peripheral side.

[0061] like Figure 2 As shown, multiple discs 83 have an outer diameter approximately equal to the outer diameter of the valve seat portion 48 of the piston 18, and can be seated on the valve seat portion 48. Disc 84 has an outer diameter smaller than the outer diameter of disc 83 and smaller than the outer diameter of the inner seat portion 47 of the piston 18. Disc 85 has an outer diameter larger than the outer diameter of disc 84 and smaller than the outer diameter of disc 83.

[0062] Multiple discs 83 constitute an extended side of the main valve 91 that can be disengaged from and seated relative to the valve seat portion 48. The main valve 91 disengages from the valve seat portion 48, thereby connecting the passage in the passage hole 37 to the lower chamber 20 and generating a damping force by inhibiting the flow of oil between itself and the valve seat portion 48.

[0063] The passage between the main valve 91 and the valve seat portion 48, which appears when the valve is opened, and the passage within the passage hole 37, constitute the first passage 92 on the extended side, through which oil flows from the upper chamber 19 (upstream side) to the lower chamber 20 (downstream side) within the cylinder 2, caused by the movement of the piston 18. The first damping force generating mechanism 41 on the extended side, which generates damping force, includes the main valve 91 and the valve seat portion 48. Thus, the first damping force generating mechanism 41 is provided in this first passage 92. The first passage 92 is provided in the piston 18, which includes the valve seat portion 48, and supplies oil through it when the piston rod 21 and the piston 18 move on the extended side.

[0064] In the first damping force generating mechanism 41 on the extension side, neither the valve seat portion 48 nor the main valve 91 abutting therewith has a fixed throttling section that connects the upper chamber 19 and the lower chamber 20 even when they are in contact. That is, if the valve seat portion 48 and the main valve 91 are in contact throughout their entire circumference, the first damping force generating mechanism 41 on the extension side will not connect the upper chamber 19 and the lower chamber 20. In other words, the first passage 92 does not have a fixed throttling section that always connects the upper chamber 19 and the lower chamber 20, and is not a passage that always connects the upper chamber 19 and the lower chamber 20.

[0065] On the side of the first damping force generating mechanism 41 opposite to the piston 18 on the extended side, starting from the side of the first damping force generating mechanism 41, there are sequentially arranged a cap component 101, a passage forming component 102, a disc 103, a disc 104, multiple (specifically two) discs 105 with the same inner and outer diameters, a valve seat component 106 with an O-ring 107 on its outer circumference, multiple (specifically three) discs 108 with the same inner and outer diameters, multiple (specifically two) discs 109 with the same inner and outer diameters, a disc 110, and an annular component 111. On the mounting shaft 28 of the piston rod 21, an external thread 31 is formed on a portion protruding from the annular component 111 towards the side opposite to the piston 18. A nut 112 is screwed into this external thread 31. The nut 112 abuts against the annular component 111.

[0066] The cap component 101, the passage forming component 102, the discs 103-105, the valve seat component 106, the discs 108-110, and the annular component 111 are all made of metal. The discs 103-105, 108-110, and the annular component 111 are all perforated circular flat plates of a certain thickness capable of fitting the mounting shaft portion 28 of the piston rod 21 internally. The cap component 101, the passage forming component 102, and the valve seat component 106 are all annular in shape capable of fitting the mounting shaft portion 28 of the piston rod 21 internally.

[0067] The cap component 101 is a one-piece molded cylindrical part with a bottom. The cap component 101 is formed by deep drawing of a sheet metal. The cap component 101 has a perforated circular plate-shaped bottom 122, a central conical portion 123 that expands in diameter and extends protruding from the outer periphery of the bottom 122 towards one axial side of the bottom 122, a cylindrical portion 124 that extends protruding from the end edge of the central conical portion 123 on the opposite side of the bottom 122 in the opposite direction to the bottom 122, and an opening-expanding portion 125 that expands in diameter and extends protruding from the end edge of the cylindrical portion 124 on the opposite side of the central conical portion 123 in the opposite direction to the central conical portion 123. The cap component 101 is arranged with the bottom 122 facing towards the piston 18. The cap component 101 is fitted into the mounting shaft portion 28 at the inner periphery of the bottom 122.

[0068] The cap component 101 has a generally certain thickness, and the outer diameter of its bottom 122 is the same as the outer diameter of the disc 83 constituting the main valve 91. The cap component 101 is thicker than the disc 83 and has a bottomed cylindrical shape, thus making it more rigid than the disc 83. Therefore, the cap component 101, by means of the disc 85 abutting against it, restricts the deformation of the main valve 91, which is composed of multiple discs 83, in the opening direction by a predetermined amount.

[0069] The valve seat component 106 has a perforated circular plate-shaped main body 132 with a through hole 131 formed in the radial center. The through hole 131 extends through the main body 132 in the thickness direction. A mounting shaft 28 is inserted into the through hole 131. On one axial side of the main body 132, the valve seat component 106 has an inner seat portion 134, an intermediate valve seat portion 135, and an outer valve seat portion 136 in sequence from the radially inner side of the main body 132. On the other axial side of the main body 132, an inner seat portion 138 and a valve seat portion 139 are provided in sequence from the radially inner side of the main body 132.

[0070] The inner seat portion 134 is annular and protrudes to one side from the inner periphery of the main body portion 132 along the axial direction of the main body portion 132. The intermediate valve seat portion 135 is also annular and protrudes from the radial center of the main body portion 132 along the axial direction of the main body portion 132 to the same side as the inner seat portion 134. The outer valve seat portion 136 is also annular and protrudes from the radial outer periphery of the main body portion 132 along the axial direction of the main body portion 132 to the same side as the inner seat portion 134.

[0071] The inner seat portion 138 is also annular, protruding from the inner periphery of the main body portion 132 along the axial direction of the main body portion 132 towards the side opposite to the inner seat portion 134. Both inner seat portions 134 and 138 form a through hole 131 radially inward and have the same outer diameter. The valve seat portion 139 is also annular, protruding from the radial center of the main body portion 132 along the axial direction of the main body portion 132 towards the same side as the inner seat portion 138. The intermediate valve seat portion 135 and the valve seat portion 139 have the same inner diameter and the same outer diameter.

[0072] In the main body 132, an inner passage hole 141 is formed between the inner seat portions 134 and 138 and the intermediate valve seat portion 135 and valve seat portion 139, extending axially through the main body 132. Multiple inner passage holes 141 are formed at equal intervals along the circumference of the main body 132. In the main body 132, an outer passage hole 143 is formed between the intermediate valve seat portion 135 and the outer valve seat portion 136, and radially outward of the valve seat portion 139, extending axially through the main body 132. The outer passage hole 143 is radially positioned outward of the inner passage holes 141 in the main body 132. Multiple outer passage holes 143 are formed at equal intervals along the circumference of the main body 132.

[0073] An annular sealing groove 145, recessed radially inward, is formed at the axial midpoint of the outer periphery of the main body 132. An O-ring 107 is disposed within this sealing groove 145. With the inner seat portion 134, the intermediate valve seat portion 135, and the outer valve seat portion 136 facing the bottom 122, the valve seat component 106 is fitted into the cylindrical portion 124 of the cap component 101 within the main body 132. Thus, the valve seat component 106 is disposed within the cap component 101. In this state, the O-ring 107 seals the gap between the cylindrical portion 124 of the cap component 101 and the main body 132 of the valve seat component 106. The valve seat component 106 is fitted into the mounting shaft portion 28 within the through hole 131.

[0074] A cap component 101, a valve seat component 106, and an O-ring 107 constitute a housing 147 with a cap chamber 146 formed on the inside. The cap chamber 146 is located between the bottom 122 of the cap component 101 and the valve seat component 106 within the housing 147. A passage forming component 102, a disc 103, a disc 104, and a plurality of discs 105 are disposed within the cap chamber 146. The intermediate valve seat portion 135 and the outer valve seat portion 136 of the valve seat component 106 are disposed on the cap chamber 146 side, and the valve seat portion 139 is disposed on the lower chamber 20 side. The housing 147 includes the annular valve seat component 106 disposed within the lower chamber 20. The valve seat component 106 divides the cap chamber 146 and the lower chamber 20, and is disposed facing both the cap chamber 146 and the lower chamber 20.

[0075] The passage forming member 102 has an outer diameter smaller than the outer diameter of the bottom 122 of the cap member 101. A small-diameter fitting hole 151 is formed on one axial side at the radial center of the passage forming member 102, and a large-diameter hole 152 larger than the small-diameter fitting hole 151 is formed on the other axial side. A passage groove 153 is formed on the axial side of the large-diameter hole 152, extending radially from the large-diameter hole 152 to the outer peripheral surface. Multiple passage grooves 153 are arranged at equal intervals along the circumference of the passage forming member 102. The passage forming member 102 is formed into this shape from a single component, for example, by machining. The passage forming member 102 is arranged with the large-diameter hole 152 and the passage groove 153 facing towards the bottom 122 side. The passage forming member 102 fits into the mounting shaft portion 28 in the small-diameter fitting hole 151. The passage within the large-diameter hole 152 of the passage forming component 102 is always connected to the passage within the passage notch 30 of the piston rod 21.

[0076] The passage within the large-diameter bore 152 of the passage forming component 102 and the passage within the passage groove 153 are always connected to the cap chamber 146 and the passage within the passage notch 30 of the piston rod 21. Thus, the cap chamber 146 is always connected to the upper chamber 19 via the passage within the large-diameter bore 152 of the passage forming component 102 and the passage within the passage groove 153, the passage within the passage notch 30 of the piston rod 21, the passage within the large-diameter bore 46 of the piston 18, the passage within the notch 88 of the disc 82, and the passage within the passage bore 37 of the piston 18.

[0077] Multiple discs 105 have an outer diameter substantially the same as the outer diameter of the outer valve seat portion 136 of the valve seat component 106. The multiple discs 105 always abut against the inner seat portion 134 and can be seated on both the outer valve seat portion 136 and the intermediate valve seat portion 135. In each of the multiple discs 105, a through hole 161 is formed at a radially midpoint between the inner seat portion 134 and the intermediate valve seat portion 135, extending axially. The passage within the through hole 161 ensures that the passage within the inner passage hole 141 of the valve seat component 106 is always connected to the cap chamber 146.

[0078] Disc 104 has an outer diameter that is smaller than the outer diameter of disc 105 and the outer diameter of passage forming member 102, and is approximately the same as the outer diameter of inner seat portion 134 of valve seat member 106. Disc 103 has an outer diameter that is larger than the outer diameter of passage forming member 102 and smaller than the outer diameter of disc 105.

[0079] Multiple discs 105 constitute a secondary valve 171 (secondary valve) capable of separating from and repositioning relative to the outer valve seat portion 136 and the intermediate valve seat portion 135. The secondary valve 171 is located within the cap chamber 146. Within the cap chamber 146, the secondary valve 171 separates from the outer valve seat portion 136, thereby connecting the passage in the outer passage hole 143 to the cap chamber 146, and connecting the lower chamber 20 to the passage in the passage hole 37, i.e., the upper chamber 19. At this time, the secondary valve 171 generates a damping force by inhibiting the flow of oil between itself and the outer valve seat portion 136. The secondary valve 171 is an inflow valve that opens when oil flows from the lower chamber 20 into the cap chamber 146 through the passage in the outer passage hole 143. The secondary valve 171 is a one-way valve that restricts the inflow of oil from the cap chamber 146 into the lower chamber 20 through the passage in the outer passage hole 143.

[0080] The passage within the outer passage hole 143, the passage between the secondary valve 171 appearing during valve opening and the outer valve seat portion 136, the cap chamber 146, the passage within the passage groove 153 of the passage forming member 102 and the passage within the large-diameter hole 152, the passage within the passage notch 30 of the piston rod 21, the passage within the large-diameter hole portion 46 of the piston 18, the passage within the notch 88 of the disc 82, and the passage within the passage hole 37 constitute a second passage 172 through which the supplied oil flows from the lower chamber 20, which is upstream, to the upper chamber 19, which is downstream, within the cylinder body 2 as the piston 18 moves. The second passage 172 is a compression-side passage where, as the piston 18 moves towards the lower chamber 20, in other words, during the compression stroke, the supplied oil flows from the lower chamber 20, which is upstream, towards the upper chamber 19, which is downstream. The second passage 172 includes a passage within the passage notch 30 formed by cutting the piston rod 21. In other words, a portion of the second passage 172 is formed by cutting the piston rod 21.

[0081] The secondary valve 171, the outer valve seat portion 136, the intermediate valve seat portion 135, the discs 103 and 104, the passage forming component 102, and the cap component 101 constitute the second damping force generating mechanism 173 on the compression side. The second damping force generating mechanism 173 is located in the second passage 172 on the compression side. The second damping force generating mechanism 173 opens and closes the second passage 172, suppressing the flow of oil from the second passage 172 to the upper chamber 19, thereby generating a damping force. In other words, the outer valve seat portion 136 and the intermediate valve seat portion 135 of the second damping force generating mechanism 173 are located in the valve seat component 106. The secondary valve 171 constituting the second damping force generating mechanism 173 on the compression side is a secondary valve on the compression side.

[0082] In the second passage 172, when the second damping force generating mechanism 173 is in the open state, the passage within the notch 88 of the disc 82 becomes the narrowest among the portions with a fixed flow cross-sectional area, becoming the throttling section 175 in the second passage 172. The throttling section 175 supplies oil to flow in the second passage 172 and is located downstream of the secondary valve 171, which supplies oil flow when the secondary valve 171 is open.

[0083] The second damping force generating mechanism 173 on the compression side does not have a fixed throttling section that connects the upper chamber 19 and the lower chamber 20 even when they are in contact, in either the outer valve seat portion 136, the intermediate valve seat portion 135, or any of the abutting secondary valves 171. That is, if the outer valve seat portion 136 and the intermediate valve seat portion 135 are in contact with the disc 105 around its entire circumference, the second damping force generating mechanism 173 on the compression side will not connect the upper chamber 19 and the lower chamber 20. In other words, the second passage 172 does not have a fixed throttling section that always connects the upper chamber 19 and the lower chamber 20; it is not a passage that always connects the upper chamber 19 and the lower chamber 20. The passage forming member 102 is thicker and more rigid than the disc 105 constituting the secondary valve 171. The passage forming member 102, together with the disc 103, restricts the deformation of the secondary valve 171 in the opening direction by a predetermined amount.

[0084] A second passage 172 on the compression side, connecting the upper chamber 19 and the lower chamber 20, is arranged side-by-side with a first passage 72 on the compression side, which also connects the upper chamber 19 and the lower chamber 20. A first damping force generating mechanism 42 is provided in the first passage 72. A second damping force generating mechanism 173 is provided in the second passage 172. Thus, the first damping force generating mechanism 42 and the second damping force generating mechanism 173 on the compression side are arranged side-by-side.

[0085] Multiple discs 108 have an outer diameter that is approximately equal to the outer diameter of the valve seat portion 139 of the valve seat component 106, and are always in contact with the inner seat portion 138, and can be seated in the valve seat portion 139. The outer diameter of the disc 108 is smaller than that of the disc 105, and the disc 108 has higher rigidity than the disc 105.

[0086] Multiple discs 109 have an outer diameter that is smaller than the outer diameter of disc 108 and approximately the same as the outer diameter of the inner seat portion 138 of valve seat component 106. Disc 110 has an outer diameter that is larger than the outer diameter of disc 109 and smaller than the outer diameter of disc 108.

[0087] The annular component 111 has an outer diameter that is larger than that of the disk 110 and smaller than that of the disk 108, and is thicker and more rigid than the disk 108.

[0088] Multiple discs 108 constitute a secondary valve 181 (first secondary valve) that can separate from and seat relative to the valve seat portion 139. The secondary valve 181 is located within the lower chamber 20. By separating from the valve seat portion 139, the secondary valve 181 connects the cap chamber 146 and the lower chamber 20 via a passage in the through hole 161 of the disc 105 and a passage in the inner passage hole 141. Thus, the secondary valve 181 connects the upper chamber 19 to the lower chamber 20. At this time, the secondary valve 181 generates a damping force by suppressing the flow of oil between itself and the valve seat portion 139. The secondary valve 181 is a discharge valve that opens when oil is discharged from the cap chamber 146 into the lower chamber 20 via the passage in the through hole 161 of the disc 105 and the passage in the inner passage hole 141. The secondary valve 181 is a one-way valve that restricts the inflow of oil from the lower chamber 20 into the cap chamber 146 via the passage in the inner passage hole 141.

[0089] The passage within the passage hole 37 of piston 18, the passage within the notch 88 of disc 82, the passage within the large-diameter bore 46 of piston 18, the passage within the passage notch 30 of piston rod 21, the passage within the large-diameter bore 152 and the passage groove 153 of passage forming member 102, the passage within the cap chamber 146, the passage within the through hole 161 of disc 105, the passage within the inner passage hole 141, the passage between the auxiliary valve 181 that appears when the valve is opened, and the passage between the valve seat portion 139 constitutes a second passage 182 through which the oil supply flows from the upper chamber 19 (upstream side) to the lower chamber 20 (downstream side) within cylinder 2 by the movement of piston 18. The second passage 182 is a passage on the extension side such that when piston 18 moves towards the upper chamber 19, in other words, during the extension stroke, the oil supply flows from the upper chamber 19 (upstream side) towards the lower chamber 20 (downstream side). The second passage 182 includes a passage within the passage notch 30 formed by cutting piston rod 21. In other words, a portion of the second passage 182 is formed by cutting the piston rod 21.

[0090] The secondary valve 181, valve seat portion 139, multiple discs 109 and 110, and annular component 111 constitute the second damping force generating mechanism 183 on the extension side. The second damping force generating mechanism 183 is located in the second passage 182 on the extension side. The second damping force generating mechanism 183 opens and closes the second passage 182, suppressing the flow of oil from the second passage 182 into the lower chamber 20 to generate damping force. In other words, the valve seat portion 139 of the second damping force generating mechanism 183 is located in the valve seat component 106. The secondary valve 181 constituting the second damping force generating mechanism 183 on the extension side is a secondary valve on the extension side.

[0091] In the second passage 182, when the second damping force generating mechanism 183 is in the open state, the passage within the notch 88 of the disc 82 becomes the narrowest among the portions with a fixed flow cross-sectional area, thus becoming a throttling section 175 in the second passage 182. The throttling section 175 is shared in both the second passages 172 and 182. The throttling section 175 supplies oil flow in the second passage 182 and is positioned upstream of the auxiliary valve 181, which supplies oil flow when the auxiliary valve 181 is open. The throttling section 175 is formed by cutting the disc 82 in the first damping force generating mechanism 41 that abuts against the piston 18.

[0092] The disc 108 constituting the secondary valve 181 has higher rigidity than the disc 105 constituting the secondary valve 171, and the secondary valve 181 has higher rigidity than the secondary valve 171. Therefore, the secondary valve 171, acting as an inflow valve into the cap chamber 146, has a lower opening pressure than the secondary valve 181, acting as a discharge valve out of the cap chamber 146. The secondary valves 181 and 171 open and close independently.

[0093] The second damping force generating mechanism 183 on the extended side does not have a fixed throttling section on either the valve seat portion 139 or the disc 108 abutting thereto, which would connect the upper chamber 19 and the lower chamber 20 even when they are in contact. That is, if the valve seat portion 139 and the disc 108 are in contact around the entire circumference, the second damping force generating mechanism 183 on the extended side will not connect the upper chamber 19 and the lower chamber 20. In other words, the second passage 182 does not have a fixed throttling section that always connects the upper chamber 19 and the lower chamber 20, and is not a passage that always connects the upper chamber 19 and the lower chamber 20. The annular member 111 uses the disc 110 to limit the deformation of the secondary valve 181 in the opening direction by a predetermined amount.

[0094] Regarding the buffer 1, at least for the axial flow of oil through the piston 18, the upper chamber 19 and the lower chamber 20 can only be connected via the first damping force generating mechanisms 41 and 42 and the second damping force generating mechanisms 173 and 183. Thus, the buffer 1 does not have a fixed throttling section in the axial passage of oil through the piston 18 to keep the upper chamber 19 and the lower chamber 20 always connected.

[0095] The second passage 182, which connects the upper chamber 19 and the lower chamber 20 on the extended side, is parallel to the first passage 92, which also connects the upper chamber 19 and the lower chamber 20 on the extended side, except for the passage within the passage hole 37 on the upper chamber 19 side. In the parallel section of the second passage 182 and the first passage 92, the first passage 92 is provided with a first damping force generating mechanism 41, and the second passage 182 is provided with a second damping force generating mechanism 183. Thus, the first damping force generating mechanism 41 and the second damping force generating mechanism 183 on the extended side are arranged side by side.

[0096] The second damping force generating mechanisms 173 and 183 include a valve seat component 106, a secondary valve 181 disposed on one side (lower chamber 20 side) of the second passages 172 and 182 of the valve seat component 106 and a secondary valve 171 disposed on the other side (upper chamber 19 side), and a bottomed cylindrical cap component 101 disposed between the piston 18 in the second passages 172 and 182 and the valve seat component 106. The secondary valve 181 is disposed on the lower chamber 20 side of the valve seat component 106, and the secondary valve 171 is disposed in the cap chamber 146 between the bottom 122 of the cap component 101 and the valve seat component 106.

[0097] like Figure 1 As shown, the aforementioned base valve 25 is provided between the bottom component 12 of the outer cylinder 4 and the inner cylinder 3. The base valve 25 has a base valve component 191 that separates the lower chamber 20 and the liquid storage chamber 6, a disc 192 located on the lower side of the base valve component 191, in other words, on the side of the liquid storage chamber 6, a disc 193 located on the upper side of the base valve component 191, in other words, on the side of the lower chamber 20, and a mounting pin 194 for mounting the disc 192 and the disc 193 to the base valve component 191.

[0098] The base valve component 191 is annular. A mounting pin 194 is inserted into the radial center of the base valve component 191. The base valve component 191 has multiple passage holes 195 allowing oil to flow between the lower chamber 20 and the reservoir 6, and multiple passage holes 196 further radially outward of the base valve component 191 allowing oil to flow between the lower chamber 20 and the reservoir 6. A disc 192 on the reservoir 6 side allows oil to flow from the lower chamber 20 to the reservoir 6 via the passage holes 195, while inhibiting oil flow from the reservoir 6 to the lower chamber 20 via the passage holes 195. A disc 193 allows oil to flow from the reservoir 6 to the lower chamber 20 via the passage holes 196, while inhibiting oil flow from the lower chamber 20 to the reservoir 6 via the passage holes 196.

[0099] Disc 192, using base valve component 191, forms a damping valve mechanism 197 on the compression side, which opens during the compression stroke of the buffer 1 to allow oil to flow from the lower chamber 20 to the reservoir 6 and generates a damping force. Disc 193, together with base valve component 191, forms a suction valve mechanism 198, which opens during the extension stroke of the buffer 1 to allow oil to flow from the reservoir 6 to the lower chamber 20. Furthermore, the suction valve mechanism 198 primarily functions to allow oil to flow from the reservoir 6 to the lower chamber 20 without substantially generating a damping force, thus compensating for insufficient fluid due to the extension of the piston rod 21 from the cylinder 2.

[0100] like Figure 2As shown, when the piston 18 and the like are assembled onto the piston rod 21, while the mounting shaft portion 28 of the piston rod 21 is inserted, an annular member 67, a disc 66, a disc 65, multiple discs 64, multiple discs 63, a disc 62, and the piston 18 are sequentially overlapped on the shaft step portion 29. At this time, the piston 18 faces the side of the shaft step portion 29 with its small-diameter bore portion 45 facing it. Furthermore, while the mounting shaft portion 28 is inserted, a disc 82, multiple discs 83, discs 84, discs 85, and a cap member 101 are sequentially overlapped on the piston 18. At this time, the cap member 101 faces the side opposite to the piston 18 with its enlarged diameter opening portion 125 facing it, and abuts against the disc 85 at its bottom 122. Then, while the mounting shaft portion 28 is inserted, a passage forming member 102 is overlapped on the bottom 122 of the cap member 101. At this time, the passage forming member 102 faces the side of the bottom 122 with its large-diameter bore 152 and passage groove 153 facing it.

[0101] Based on this, while inserting the mounting shaft 28, a valve seat component 106 is formed in the passageway, consisting of overlapping discs 103, 104, multiple discs 105, and an O-ring 107. At this time, the valve seat component 106 is positioned with the inner seat 134, the middle seat 135, and the outer seat 136 facing the multiple discs 105, and the main body 132 and the O-ring 107 are fitted into the cylindrical portion 124 of the cap component 101. Furthermore, while inserting the mounting shaft 28, multiple discs 108, multiple discs 109, disc 110, and an annular component 111 are overlapped on the valve seat component 106. In this state, the nut 112 is screwed into the external thread 31 of the piston rod 21, which protrudes beyond the annular component 111, and the nut 112 and the shaft step portion 29 clamp their inner circumferences axially.

[0102] In this state, the main valve 71 is clamped to its inner circumference by the inner seat 49 and the disc 65 of the piston 18 via the disc 62, and abuts against the valve seat 50 of the piston 18 throughout its circumference. In this state, the main valve 91 is clamped to its inner circumference by the inner seat 47 and the disc 84 of the piston 18 via the disc 82, and abuts against the valve seat 48 of the piston 18 throughout its circumference. In this state, the secondary valve 171 is clamped to its inner circumference by the inner seat 134 and the disc 104 of the valve seat component 106, and abuts against the intermediate valve seat 135 and the outer valve seat 136 of the valve seat component 106 throughout its circumference. In this state, the secondary valve 181 is clamped to its inner circumference by the inner seat 138 and the disc 109 of the valve seat component 106, and abuts against the valve seat 139 of the valve seat component 106 throughout its circumference.

[0103] Figure 4 The diagram above shows the hydraulic circuit diagram of the buffer 1 according to the first embodiment. Figure 4As shown, a first damping force generating mechanism 41 on the extension side of the first passage 92 connecting the upper chamber 19 and the lower chamber 20 is provided. A second damping force generating mechanism 183 on the extension side of the second passage 182 connecting the upper chamber 19 and the lower chamber 20 is provided parallel to the first damping force generating mechanism 41. A first damping force generating mechanism 42 on the compression side of the first passage 72 connecting the lower chamber 20 and the upper chamber 19 is provided. A second damping force generating mechanism 173 on the compression side of the second passage 172 connecting the lower chamber 20 and the upper chamber 19 is provided parallel to the first damping force generating mechanism 42. Furthermore, a throttling section 175 is provided in the common portion of the second passages 172 and 182 on the side closer to the upper chamber 19 than the second damping force generating mechanisms 173 and 183. Additionally, as described above, the buffer 1 does not have a fixed throttling section that keeps the upper chamber 19 and the lower chamber 20 in constant communication.

[0104] like Figure 2 As shown, the main valve 91 of the first damping force generating mechanism 41 in the first damping force generating mechanism 41 and the second damping force generating mechanism 183 on the extension side has higher rigidity and higher opening pressure than the secondary valve 181 of the second damping force generating mechanism 183. Therefore, during the extension stroke, in the extremely low-speed region where the piston speed is lower than a specified value, the second damping force generating mechanism 183 opens while the first damping force generating mechanism 41 is closed. In the normal speed region where the piston speed is above the specified value, both the first damping force generating mechanism 41 and the second damping force generating mechanism 183 are open. The secondary valve 181 is an extremely low-speed valve that generates damping force by opening in the region where the piston speed is extremely low.

[0105] That is, during the extension stroke, the piston 18 moves towards the upper chamber 19, causing the pressure in the upper chamber 19 to increase and the pressure in the lower chamber 20 to decrease. However, since there is no fixed throttling section in either the first damping force generating mechanisms 41 and 42 or the second damping force generating mechanisms 173 and 183, no oil flows through until the second damping force generating mechanism 183 opens its valve. Therefore, as Figure 5 As shown, during the extension stroke when the piston speed (PS) is less than the first predetermined value v1, the damping force (DF) increases sharply. In the region where the piston speed (PS) is higher than the first predetermined value v1 at which the second damping force generating mechanism 183 opens, and in the extremely low-speed region where the speed is lower than the second predetermined value v2 at which the speed is higher than the first predetermined value v1 (above v1 and below v2), the second damping force generating mechanism 183 opens when the first damping force generating mechanism 41 is closed.

[0106] That is, the secondary valve 181 leaves the valve seat portion 139, and the upper chamber 19 is connected to the lower chamber 20 via the second passage 182 on the extended side. Thus, the oil in the upper chamber 19 flows to the lower chamber 20 via the passage in the passage hole 37 of the piston 18, the throttling portion 175, the passage in the large-diameter hole portion 46 of the piston 18, the passage in the passage notch portion 30 of the piston rod 21, the large-diameter hole 152 of the passage forming member 102, the passage in the passage groove 153, the cap chamber 146, the passage in the through hole 161 of the secondary valve 171, the passage in the inner passage hole 141, and the passage between the secondary valve 181 and the valve seat portion 139. Therefore, even in the extremely low-speed region (above v1 and below v2) where the piston speed (PS) is lower than the second predetermined value v2, the damping force of the valve characteristic (the characteristic that the damping force is approximately proportional to the piston speed) can be obtained.

[0107] During the extension stroke, in the normal speed range where the piston speed is above the second predetermined value v2, the first damping force generating mechanism 41 opens while the second damping force generating mechanism 183 remains open. That is, the auxiliary valve 181 moves away from the valve seat portion 139, allowing oil to flow from the upper chamber 19 to the lower chamber 20 via the second passage 182 on the extension side. At this time, the flow of oil is throttled by the throttling portion 175 located downstream of the main valve 91 in the second passage 182, causing the pressure applied to the main valve 91 to increase, the differential pressure to rise, and the main valve 91 moves away from the valve seat portion 48, allowing oil to flow from the upper chamber 19 to the lower chamber 20 via the first passage 92 on the extension side. Thus, the oil in the upper chamber 19 flows to the lower chamber 20 via the passage in the passage hole 37, the passage between the main valve 91 and the valve seat portion 48.

[0108] Here, during the extension stroke, in the normal speed range where the piston speed (PS) is above the second predetermined value v2, and in the low-speed range where the differential pressure between the upper chamber 19 and the lower chamber 20 is above the first predetermined value v1 but below the second predetermined value v2, since the first passage 92 is not throttled based on the throttling section, the oil can flow through the first passage 92 at a large flow rate by opening the main valve 91. Furthermore, by throttling the second passage 182 using the throttling section 175, deformation of the secondary valve 181 can be suppressed.

[0109] At this time, pressure in the opposite direction is applied from the lower chamber 20 and the cap chamber 146 to the closed auxiliary valve 171. Even if the pressure difference between the upper chamber 19 and the lower chamber 20 increases, because a throttling section 175 is formed in the second passage 182 upstream of the auxiliary valve 171, the pressure rise in the cap chamber 146 is slower relative to the pressure rise in the upper chamber 19, thus suppressing the increase in the pressure difference between the cap chamber 146 and the lower chamber 20. As a result, the pressure difference between the cap chamber 146 and the lower chamber 20 on the closed auxiliary valve 171 can be suppressed, and a large back pressure from the cap chamber 146 side toward the lower chamber 20 side can be suppressed from being applied to the auxiliary valve 171.

[0110] During its extension stroke, the buffer 1 allows oil to flow from the upper chamber 19 to the lower chamber 20 through a parallel arrangement of the first passage 92 and the second passage 182, and a main valve 91 and a secondary valve 181 are arranged in parallel. The throttling section 175 and the secondary valve 181 are connected in series.

[0111] As described above, during the extended stroke, in the normal speed range where the piston speed (PS) is above the second predetermined value v2, the main valve 91 opens, allowing oil to flow at a high flow rate through the first passage 92. Consequently, the flow rate through the passage between the secondary valve 181 and the valve seat 139 decreases. Therefore, the valve rigidity of the secondary valve 181 can be reduced.

[0112] Therefore, for example Figure 5 As shown, the rate of increase of the damping force (DF) relative to the increase of the piston speed (v2 and above) in the normal speed range (PS) can be made to decrease as shown by the solid line X2 instead of the dashed line X1. In other words, the slope of the rate of increase of the damping force (DF) on the extension side relative to the increase of the piston speed (PS) in the normal speed range (v2 and above) can be flattened compared to the extremely low speed range (less than v2). This increases the design freedom.

[0113] Both the first damping force generating mechanism 42 and the second damping force generating mechanism 173 exist on the compression side. The main valve 71 of the first damping force generating mechanism 42 has higher rigidity and a higher opening pressure than the auxiliary valve 171 of the second damping force generating mechanism 173. Therefore, during the compression stroke, in the extremely low-speed region where the piston speed is lower than a specified value, the second damping force generating mechanism 173 opens while the first damping force generating mechanism 42 is closed. In the normal speed region where the piston speed is above the specified value, both the first damping force generating mechanism 42 and the second damping force generating mechanism 173 are open. The auxiliary valve 171 is an extremely low-speed valve that generates damping force by opening in the region where the piston speed is extremely low.

[0114] That is, during the compression stroke, the piston 18 moves towards the lower chamber 20, causing the pressure in the lower chamber 20 to increase and the pressure in the upper chamber 19 to decrease. However, since there is no fixed throttling section in either of the first damping force generating mechanisms 41, 42 or the second damping force generating mechanisms 173, 183, no oil flows until the second damping force generating mechanism 173 opens. Therefore, the damping force increases sharply. In the region where the piston speed is higher than the third predetermined value for the second damping force generating mechanism 173 to open, and in the extremely low-speed region where the speed is lower than the fourth predetermined value for the second predetermined value, the second damping force generating mechanism 173 opens while the first damping force generating mechanism 42 is closed.

[0115] That is, the auxiliary valve 171 moves away from the outer valve seat portion 136 and connects the lower chamber 20 to the upper chamber 19 via the second passage 172 on the compression side. Thus, the oil in the lower chamber 20 flows to the upper chamber 19 via the passage in the outer passage hole 143, the passage between the auxiliary valve 171 and the outer valve seat portion 136, the cap chamber 146, the passage groove 153 and the passage in the large-diameter hole 152 of the passage forming member 102, the passage in the passage notch 30 of the piston rod 21, the passage in the large-diameter hole 46 of the piston 18, the throttling portion 175, and the passage in the passage hole 37 of the piston 18. Therefore, even in the extremely low-speed region where the piston speed is lower than the fourth specified value, the damping force of the valve characteristic (the characteristic that the damping force is approximately proportional to the piston speed) can be obtained.

[0116] During the compression stroke, in the normal speed range where the piston speed is above the fourth specified value, the first damping force generating mechanism 42 opens while the second damping force generating mechanism 173 remains open. That is, the auxiliary valve 171 moves away from the outer valve seat 136, allowing oil to flow from the lower chamber 20 to the upper chamber 19 via the second passage 172 on the compression side. At this time, the second passage 172 throttles the oil flow using the throttling section 175, thus increasing the differential pressure generated by the main valve 71. The main valve 71 moves away from the valve seat 50, allowing oil to flow from the lower chamber 20 to the upper chamber 19 via the first passage 72 on the compression side. Consequently, the oil in the lower chamber 20 flows through the passage in the passage hole 39 and the passage between the main valve 71 and the valve seat 50. Therefore, even in the normal speed range where the piston speed is above the fourth specified value, a damping force with valve characteristics (damping force approximately proportional to piston speed) can be obtained. The rate of increase of the damping force on the compression side relative to the increase of piston speed in the normal speed region is lower than that in the extremely low speed region. In other words, the slope that allows the rate of increase of the damping force on the compression side relative to the increase of piston speed in the normal speed region to be flatter is more pronounced than in the extremely low speed region.

[0117] During the compression stroke, in the normal speed range where the piston speed is above the fourth specified value, the differential pressure between the lower chamber 20 and the upper chamber 19 is larger than in the low-speed range. However, since the first passage 72 does not have throttling based on the throttling section, the oil can flow through the first passage 72 at a large flow rate by opening the main valve 71. As a result, the flow rate through the secondary valve 171 is reduced, thus reducing the valve stiffness of the secondary valve 171. This reduces damping forces in the normal speed range and increases design flexibility.

[0118] When the piston speed is high, the pressure difference between the lower chamber 20 and the upper chamber 19 increases. However, by throttling the second passage 172 through the throttling section 175, the pressure in the cap chamber 146 connected to the upper chamber 19 via the throttling section 175 becomes the pressure between the lower chamber 20 and the upper chamber 19. Therefore, it is possible to prevent the pressure difference between the lower chamber 20 and the upper chamber 19 from becoming too large. Furthermore, by opening the main valve 71, the oil can flow through the first passage 72 at a large flow rate, thereby suppressing the deformation of the secondary valve 171.

[0119] The closed secondary valve 181 is subjected to pressure in opposite directions from the lower chamber 20 and the cap chamber 146. At this time, although the pressure difference between the lower chamber 20 and the upper chamber 19 is large, the lower chamber 20 and the cap chamber 146 are connected by the open secondary valve 171, and a throttling section 175 is provided between the cap chamber 146 and the upper chamber 19, which is downstream of the secondary valve 181. Therefore, excessive pressure drop in the cap chamber 146 can be suppressed, and the pressure in the cap chamber 146 can rise in response to the pressure rise in the lower chamber 20. Consequently, the pressure difference generated between the upstream and downstream sides of the secondary valve 181 is small, and a large back pressure from the lower chamber 20 side towards the cap chamber 146 side can be suppressed from being applied to the secondary valve 181.

[0120] The buffer 1 described above, during the compression stroke, allows oil to flow from the lower chamber 20 to the upper chamber 19 through a parallel arrangement of the first passage 72 and the second passage 172, and a main valve 71 and a secondary valve 171 are arranged in parallel. The throttling section 175 is connected in series with the secondary valve 171 in the second passage 172.

[0121] In addition, during the compression stroke, the damping force characteristics of the damping valve mechanism 197 also become a matching characteristic.

[0122] During the extension stroke, in the normal speed region where the piston speed is above the second predetermined value, the differential pressure between the upper chamber 19 and the lower chamber 20 increases. However, since the pressure rise in the cap chamber 146 can be suppressed by utilizing the throttling section 175 formed upstream of the secondary valve 171, deformation caused by the back pressure of the secondary valve 171 can be suppressed. During the compression stroke, in the normal speed region where the piston speed is above the fourth predetermined value, the differential pressure between the lower chamber 20 and the upper chamber 19 is greater than in the low-speed region. However, by using the first passage 72 to allow the oil to flow at a large flow rate and by using the throttling section 175 to throttle the secondary valve 171 downstream of the second passage 172, deformation of the secondary valve 171 can be suppressed. As a result, the durability of the secondary valve 171 can be improved.

[0123] During the extension stroke, in the normal speed range where the piston speed is above the second predetermined value, the differential pressure between the upper chamber 19 and the lower chamber 20 is greater than in the low-speed range. However, by using the first passage 92 to allow the oil to flow at a high flow rate and by using the throttling section 175 to throttle the second passage 182, deformation of the secondary valve 181 can be suppressed. During the compression stroke, in the normal speed range where the piston speed is above the fourth predetermined value, the differential pressure between the lower chamber 20 and the upper chamber 19 increases. However, the lower chamber 20 and the cap chamber 146 are connected by the opening of the secondary valve 171, and the cap chamber 146 uses the throttling section 175 provided between it and the upper chamber 19 to throttle the flow of oil to the upper chamber 19. Therefore, the differential pressure between the lower chamber 20 and the cap chamber 146 is small, and deformation caused by the back pressure of the secondary valve 181 can be suppressed. As a result, the durability of the secondary valve 181 can be improved.

[0124] Because it has independent second damping force generating mechanisms 173 and 183 in both compression and extension strokes, the degree of freedom in setting the damping force characteristics is increased.

[0125] Patent Document 1 describes a method of connecting two oil chambers using parallel flow paths, with valves installed in each of these flow paths, thereby arranging valves side-by-side that open during the same stroke. By employing this configuration of valves opening during the same stroke in parallel arrangement, it is possible for one valve to open in a region where the piston speed is lower than the other, and for both valves to open in regions where the piston speed is higher. In this configuration, improving the durability of the valve on the low-speed side is particularly important.

[0126] In contrast, the buffer 1 of the first embodiment has a secondary valve 181 of the second damping force generating mechanisms 173 and 183 in the second passages 172 and 182, which are parallel to the first passages 72 and 92 of the pistons 18 of the first damping force generating mechanisms 41 and 42, located in a valve seat member 106 disposed in the lower chamber 20. Furthermore, a bottom-cylindrical cap member 101 is disposed between the piston 18 and the valve seat member 106 in the second passages 172 and 182, with the valve seat member 106 disposed inside it. In this case, the secondary valve 181 is located on the lower chamber 20 side, and the secondary valve 171 is located in the cap chamber 146 between the bottom 122 of the cap member 101 and the valve seat member 106. Moreover, a throttling section 175 is disposed upstream of the flow during the extended stroke of the secondary valve 181 in the second passage 172. Therefore, during the compression stroke, the flow of oil from the lower chamber 20 through the open auxiliary valve 171 into the cap chamber 146 and then into the upper chamber 19 is throttled by the throttling section 175. Consequently, the differential pressure between the cap chamber 146 and the lower chamber 20 decreases, and the auxiliary valve 181, which is in a closed state and experiences back pressure from the lower chamber 20, experiences the same pressure from the cap chamber 146 as from the lower chamber 20, thus suppressing the back pressure (differential pressure). This improves the durability of the auxiliary valve 181.

[0127] The second passages 172 and 182 are not always connected and do not have a fixed throttling section that is always connected. Therefore, they are more effective at suppressing the back pressure on the secondary valve 181.

[0128] Because the piston rod 21 is inserted into the piston 18, the cap part 101, and the valve seat part 106, the piston 18, the cap part 101, and the valve seat part 106 can be arranged compactly.

[0129] Since the throttling section 175 is formed by cutting the disc 82 that abuts against the piston 18 in the first damping force generating mechanism 41 on the extension side, the throttling section 175 can be easily formed.

[0130] Since the second passages 172 and 182 are formed by cutting a portion of the piston rod 21, the second passages 172 and 182 can be easily formed.

[0131] Since the secondary valve 171, which acts as an inflow valve into the cap chamber 146, opens at a lower pressure than the secondary valve 181, it is easier for oil to flow into the cap chamber 146 from the lower chamber 20 during the compression stroke. Therefore, even when the pressure in the lower chamber 20 is lower, the closed secondary valve 181 experiences the same pressure from the cap chamber 146 as the lower chamber 20, suppressing back pressure. This further improves the durability of the secondary valve 181.

[0132] Since the pressure difference between the cap chamber 146 and the lower chamber 20 does not increase during the two strokes of extension and retraction, a thin sheet metal stamped component can be used for the cap component 107. Therefore, it is advantageous in terms of manufacturability and weight reduction.

[0133] [Second Implementation]

[0134] Next, mainly based on Figure 6 The second embodiment will be described focusing on the parts that differ from the first embodiment. Furthermore, parts common to the first embodiment will be indicated using the same names and reference numerals.

[0135] In the buffer 1A of the second embodiment, as Figure 6 As shown, the housing 147, which is the same as that in the first embodiment, consists of a cap component 101, a valve seat component 106, and an O-ring 107, a passage forming component 102, a disc 103, a disc 104 disposed therein, a compression-side auxiliary valve 171, and an extension-side auxiliary valve 181 on the side of the valve seat component 106 opposite to the auxiliary valve 171, are arranged such that their axial orientation is opposite to that in the first embodiment.

[0136] On the side of the main valve 91, which is the same as in the first embodiment, opposite to the piston 18, there is no disc 85 as in the first embodiment, but instead a plurality of (specifically, three) discs 84 identical to those in the first embodiment. On the side of these discs 84 opposite to the main valve 91, a secondary valve 181 consisting of a plurality of (specifically, three) discs 108 overlaps. On the side of the secondary valve 181 opposite to the discs 84, an inner seat portion 138 and a valve seat portion 139 overlap on the valve seat component 106 facing the secondary valve 181.

[0137] Furthermore, on the side opposite to the auxiliary valve 181, the inner seat portion 134, the middle seat portion 135, and the outer seat portion 136 of the valve seat component 106 are overlapped with a compression-side auxiliary valve 171 consisting of multiple (specifically two) discs 105. Discs 104 and 103, and a passage forming component 102 are sequentially overlapped on the auxiliary valve 171. The passage forming component 102 faces the side of the small-diameter fitting hole 151 towards the disc 103.

[0138] Furthermore, the cap component 101 covers the valve seat component 106, the auxiliary valve 171, the disc 104, the disc 103, and the passage forming component 102, with its bottom 122 abutting against the large-diameter hole 152 and the passage groove 153 side of the passage forming component 102, and the cylindrical portion 124 fitting into and covering the main body portion 132 and the O-ring 107 of the valve seat component 106.

[0139] On the bottom 122 of the cap component 101, opposite to the passage forming component 102, overlaps a disc 211, a disc 109 (similar to the first embodiment), a disc 110 (also identical to the first embodiment), and an annular component 111. Furthermore, a nut 112 is screwed into the annular component 111 on the side opposite to the disc 110, using an external thread 31. The disc 211 is made of metal. The disc 211 is a perforated circular plate of a certain thickness, capable of fitting the mounting shaft portion 28 of the piston rod 21 internally. The outer diameter of the disc 211 is the same as the outer diameter of the disc 110.

[0140] In the second embodiment, with the above configuration, the axial distance of the passage forming member 102 from the piston 18 is longer compared to the first embodiment. Correspondingly, the piston rod 21A of the second embodiment has a passage notch 30A that is axially longer than the passage notch 30 of the piston rod 21 of the first embodiment. The passage within this passage notch 30A communicates with the passage within the large-diameter bore 152 of the passage forming member 102.

[0141] In this second embodiment, during the compression stroke, oil flows from the lower chamber 20 to the upper chamber 19 via the passage in the outer passage hole 143, the passage between the open auxiliary valve 171 and the outer valve seat portion 136, the cap chamber 146, the passage in the passage groove 153 and the large diameter hole 152 of the passage forming member 102, the passage in the passage notch 30A of the piston rod 21A, the passage in the large diameter hole portion 46 of the piston 18, the passage in the notch 88 of the disc 82 forming the throttling portion 175, and the passage in the passage hole 37. These constitute the second passage 172A on the compression side.

[0142] During the extension stroke, oil flows from the upper chamber 19 to the lower chamber 20 via the passage in the passage hole 37 of the piston 18, the passage in the notch 88 of the disc 82 forming the throttling section 175, the passage in the large diameter hole 46 of the piston 18, the passage in the passage notch 30A of the piston rod 21A, the passage in the large diameter hole 152 and the passage groove 153 of the passage forming member 102, the passage in the cap chamber 146, the passage in the through hole 161 of the disc 105, the passage in the inner passage hole 141, and the passage between the valve-opening auxiliary valve 181 and the valve seat 139. These constitute the second passage 182A on the extension side.

[0143] The hydraulic circuit, operation, and damping force characteristics of this second embodiment of buffer 1A are the same as those of the first embodiment of buffer 1.

[0144] [Third Implementation Method]

[0145] Next, mainly based on Figure 7 The third embodiment will be described focusing on the parts that differ from the first embodiment. Furthermore, parts common to the first embodiment will be indicated using the same names and reference numerals.

[0146] In the buffer 1B of the third embodiment, as Figure 7 As shown, a piston rod 21B has a structure different from that of piston rod 21. A passage notch 30B extending to a shaft step 29 is formed in the piston rod 21B, replacing the passage notch 30. A groove 215 extending radially and communicating within the passage notch 30B is formed in the shaft step 29 of the main shaft portion 27 of the piston rod 21B. The passage within the passage notch 30B communicates with the passage within the large-diameter bore 152 of the passage forming member 102. Thus, the passages in the large-diameter bore 152 of the passage forming member 102 and the passages in the passage groove 153 are always connected to the upper chamber 19 via the passages in the passage notch 30B and the groove 215.

[0147] In the third embodiment, a piston 18B with a structure different from that of piston 18 is provided. This piston 18B has a piston body 35B with a structure different from that of piston body 35. An insertion hole 44B with the same diameter as the small-diameter hole 45 is formed in the piston body 35B instead of the insertion hole 44 with the small-diameter hole portion 45 and the large-diameter hole portion 46 of the first embodiment.

[0148] Furthermore, in the third embodiment, a first damping force generating mechanism 41B has an elongated side with a structure different from that of the first damping force generating mechanism 41 in the first embodiment. The first damping force generating mechanism 41B replaces the disc 82 with the notch 88 formed in the first embodiment, and has a disc 82B without the notch 88 formed.

[0149] In this third embodiment, during the compression stroke, oil flows from the lower chamber 20 to the upper chamber 19 via the passage in the outer passage hole 143, the passage between the open auxiliary valve 171 and the outer valve seat portion 136, the cap chamber 146, the passage groove 153 of the passage forming member 102 and the passage in the large diameter hole 152, the passage notch 30B of the piston rod 21B and the passage in the groove 215. These constitute the second passage 172B on the compression side.

[0150] In the second passage 172B, the passage within the passage groove 153 of the passage forming component 102 becomes the narrowest throttling section 175B among the fixed portions of the flow path cross-sectional area. The throttling section 175B allows oil to flow through the second passage 172B and is located downstream of the secondary valve 171, which is positioned for oil flow when the secondary valve 171 is open.

[0151] During the extension stroke, oil flows from the upper chamber 19 to the lower chamber 20 through the passages in the groove 215 of the piston rod 21B, the passage notch 30B, the large-diameter bore 152 and the passage groove 153 of the passage forming member 102, the cap chamber 146, the through hole 161 of the auxiliary valve 171, the passage in the inner passage hole 141, the passage between the opening auxiliary valve 181 and the valve seat 139. These constitute the second passage 182B on the extension side.

[0152] In the second passage 182B, the passage within the passage groove 153 of the passage forming component 102 becomes the narrowest throttling section 175B among the fixed portions of the flow path cross-sectional area. The throttling section 175B allows oil to flow through the second passage 182B and is positioned upstream of the auxiliary valve 181, which is used when the auxiliary valve 181 is open.

[0153] The hydraulic circuit, operation, and damping force characteristics of this third embodiment of buffer 1B are the same as those of the first embodiment of buffer 1.

[0154] [Fourth Implementation Method]

[0155] Next, mainly based on Figure 8 The fourth embodiment will be described focusing on the parts that differ from the first embodiment. Furthermore, parts common to the first embodiment will be indicated using the same names and reference numerals.

[0156] In the buffer 1C of the fourth embodiment, as Figure 8 As shown, the passage forming member 102 and the disc 103 of the first embodiment are not provided. Additionally, a housing 147C has a structure that differs from that of the housing 147. The housing 147C includes a valve seat member 106C with a structure that differs from that of the valve seat member 106 and a cap member 101C with a structure that differs from that of the cap member 101.

[0157] The valve seat component 106C has a through hole 131C at the radial center of the main body 132. The through hole 131C includes a large-diameter hole 221 on the axial side of the inner seat portion 134 and a small-diameter hole 222 on the axial side of the inner seat portion 138. The large-diameter hole 221 is larger than the small-diameter hole 222. The valve seat component 106C is fitted into the mounting shaft portion 28 in the small-diameter hole 222. A plurality of radially penetrating passage notches 223 are formed at equal intervals along the circumferential direction in the valve seat component 106C.

[0158] In order to connect the passage in the large-diameter bore 221 of the valve seat component 106C, the axial length of the piston rod 21C of the piston rod 21C in the fourth embodiment is longer than that of the piston rod 21 in the first embodiment.

[0159] The cap member 101C of the fourth embodiment has a bottom 122C with an outer diameter greater than that of the bottom 122 of the first embodiment, an intermediate cone 123C with a smaller axial length and radial width than the intermediate cone 123 of the first embodiment, and a cylindrical portion 124C with a longer axial length than the cylindrical portion 124. The cap member 101C restricts the deformation of its bottom 122C in the opening direction of the auxiliary valve 171 on the compression side by a predetermined amount.

[0160] In the fourth embodiment, a plurality of (specifically two) discs 104 are provided. The discs 104 abut against the bottom 122C of the cap component 101C.

[0161] In this fourth embodiment, during the compression stroke, oil flows from the lower chamber 20 to the upper chamber 19 via the passage in the outer passage hole 143, the passage between the open auxiliary valve 171 and the outer valve seat portion 136, the cap chamber 146, the passage in the through hole 161 of the auxiliary valve 171, the passage in the passage notch 223 and the passage in the large diameter hole portion 221 of the valve seat component 106C, the passage in the passage notch 30C of the piston rod 21C, the passage in the large diameter hole portion 46 of the piston 18, the passage in the notch 88 of the disc 82, and the passage in the passage hole 37. These constitute the second passage 172C on the compression side.

[0162] During the extension stroke, oil flows from the upper chamber 19 to the lower chamber 20 via the passage in the passage hole 37 of the piston 18, the passage in the notch 88 of the disc 82 forming the throttling section 175, the passage in the large-diameter bore 46 of the piston 18, the passage in the passage notch 30C of the piston rod 21C, the passage in the large-diameter bore 221 and the passage notch 223 of the valve seat component 106C, the passage in the inner passage hole 141, and the passage between the valve-opening auxiliary valve 181 and the valve seat 139. These constitute the second passage 182C on the extension side. The passage in the passage notch 223 is always in communication with the passage in the through hole 161 of the disc 105.

[0163] The hydraulic circuit, operation, and damping force characteristics of this fourth embodiment of the buffer 1C are the same as those of the buffer 1 in the first embodiment.

[0164] [Fifth Implementation]

[0165] Next, mainly based on Figure 9 as well as Figure 10 The fifth embodiment will be described focusing on the differences from the third and fourth embodiments. Furthermore, parts common to the third and fourth embodiments will be indicated using the same names and reference numerals.

[0166] In the buffer 1D of the fifth embodiment, as follows Figure 9 As shown, it includes a first damping force generating mechanism 41B containing a disc 82B, a piston 18B and a piston rod 21B, which are the same as in the third embodiment, a cap component 101C, which are the same as in the fourth embodiment, and a plurality of (specifically two) discs 104.

[0167] In the fifth embodiment, there is a housing 147D with a structure that is different from that of housing 147C. Housing 147D has a valve seat component 106D that is different from valve seat component 106C in that it does not have a passage notch 223 formed.

[0168] Additionally, a second damping force generating mechanism 173D has a structure different from that of the second damping force generating mechanism 173. The second damping force generating mechanism 173D includes a secondary valve 171D, whose structure differs from that of the disc 105 portion, which abuts against the valve seat member 106D relative to the secondary valve 171. For example... Figure 10 As shown, a notch 231 is formed in the disc 105D, extending from the radial through hole 161 to the inner peripheral edge. The passage in the notch 231 connects the passage in the passage notch 30B of the piston rod 21B and the passage in the large-diameter hole 221 of the valve seat component 106D to the passage in the inner passage hole 141.

[0169] In this fifth embodiment, during the compression stroke, via Figure 9 The passages shown in the outer passage hole 143, the passage between the open auxiliary valve 171D and the outer valve seat portion 136, the passage in the cap chamber 146, the passage in the through hole 161 of the auxiliary valve 171D, the passage in the notch portion 231 of the disc 105D, the passage in the large diameter hole portion 221 of the valve seat component 106D, and the passage notch portion 30B of the piston rod 21B allow oil to flow from the lower chamber 20 to the upper chamber 19. These constitute the second passage 172D on the compression side.

[0170] In the second passage 172D, the passage within the notch 231 of the disc 105D becomes the narrowest throttling section 175D in the fixed portion of the flow path cross-sectional area. The throttling section 175D allows oil to flow through the second passage 172D and is located downstream of the auxiliary valve 171D, which is positioned when the auxiliary valve 171D is open.

[0171] During the extension stroke, oil flows from the upper chamber 19 to the lower chamber 20 through the passage in the passage notch 30B of the piston rod 21B, the passage in the large-diameter bore 221 of the valve seat component 106C, the passage in the notch 231 of the disc 105D, the passage in the inner passage hole 141 of the valve seat component 106C, and the passage between the valve-opening auxiliary valve 181 and the valve seat 139. These constitute the second passage 182D on the extension side.

[0172] In the second passage 182D, the passage within the notch 231 of the disc 105D becomes the narrowest throttling section 175D among the fixed sections in terms of flow cross-sectional area. The throttling section 175D allows oil to flow through the second passage 182D and is positioned upstream of the auxiliary valve 181, which is used for oil flow when the auxiliary valve 181 is open.

[0173] The hydraulic circuit, operation, and damping force characteristics of this fifth embodiment of the buffer 1D are the same as those of the buffer 1 in the first embodiment.

[0174] [Sixth Implementation Method]

[0175] Next, mainly based on Figure 11 as well as Figure 12 The sixth embodiment will be described focusing on the differences from the fourth embodiment. Furthermore, parts common to the fourth embodiment will be indicated using the same names and reference numerals.

[0176] In the buffer 1E of the sixth embodiment, as Figure 11 As shown, a cap part 101E has a structure that differs from that of cap part 101C. Instead of the intermediate conical portion 123C of the fourth embodiment, cap part 101E has a bottom 122E with an increased outer diameter of the bottom 122C and a cylindrical portion 124E with an increased axial length of the cylindrical portion 124C.

[0177] The buffer 1E has a valve seat component 106E with a structure different from that of the valve seat component 106C in the fourth embodiment. The valve seat component 106E does not have a passage notch 223. The valve seat component 106E has a through hole 131E at its radial center. In the through hole 131E, a large-diameter hole 221E is formed on the axial inner seat portion 138 and valve seat portion 139 side, and a small-diameter hole 222E with a smaller diameter than the large-diameter hole 221E and fitted into the mounting shaft portion 28 is formed on the axial inner seat portion 134, intermediate valve seat portion 135 and outer valve seat portion 136 side.

[0178] Inside the housing 147E, which is composed of the cap component 101E, the valve seat component 106E, and the O-ring 107, similar to the fourth embodiment, a plurality of (specifically two) discs 104 and a compression-side auxiliary valve 171 are provided. The auxiliary valve 171 abuts against the inner seat portion 134, the intermediate valve seat portion 135, and the outer valve seat portion 136 of the valve seat component 106E. The plurality of discs 104 are disposed between the auxiliary valve 171 and the bottom 122E of the cap component 101E.

[0179] The housing 147E, the compression-side auxiliary valve 171, and the plurality of discs 104 are configured to have an axial orientation opposite to that of the fourth embodiment.

[0180] The buffer 1E has a second damping force generating mechanism 183E on an extended side, the structure of which differs from that of the second damping force generating mechanism 183. The second damping force generating mechanism 183E includes a secondary valve 181E. The structure of the disc 108E, which abuts against the inner seat portion 138 and the valve seat portion 139 of the valve seat member 106E, differs from that of the disc 108 portion, relative to the secondary valve 181 of the fourth embodiment. For example... Figure 12 As shown, a notch 241 is formed in the disc 108E, extending from the middle position of the valve seat portion 139 on the inner side to the inner peripheral edge.

[0181] like Figure 11As shown, the secondary valve 181E is also configured in the same way as the valve seat component 106E, with its axial orientation opposite to that of the fourth embodiment. That is, multiple (specifically three) discs 84 and the secondary valve 181E are sequentially overlapped on the extended side of the main valve 91. At this time, multiple (specifically two) discs 108 are arranged on the axial side of the disc 84 of the secondary valve 181E, and one disc 108E is arranged on the axial side opposite to the disc 84. Moreover, on the axial side of the secondary valve 181E opposite to the disc 84, the valve seat component 106E, the secondary valve 171, and the multiple discs 104 with the O-ring 107 installed are sequentially overlapped, and the cap component 101E is covered in such a way that it covers the valve seat component 106E, the secondary valve 171, and the multiple discs 104.

[0182] The notch 241 of the disc 108E of the secondary valve 181E is formed radially inward from the valve seat portion 139. The passage within the notch 241 connects the passage within the passage notch 30C of the piston rod 21C and the passage within the large-diameter bore 221E of the valve seat component 106E to the passage between the secondary valve 181E and the valve seat portion 139. This passage within the notch 241 connects to the cap chamber 146 via the passage within the inner passage hole 141 and the through hole 161 of the secondary valve 171.

[0183] On the bottom 122E of the cap component 101E, opposite to the side of the disk 104, overlaps a disk 242, a disk 109, a disk 110, and an annular component 111. The disk 242 is made of metal. The disk 242 is a perforated circular plate of a certain thickness, capable of fitting the mounting shaft portion 28 of the piston rod 21 internally. The outer diameter of the disk 242 is the same as the outer diameter of the disk 110.

[0184] In this sixth embodiment, during the compression stroke, if the secondary valve 171 leaves the outer valve seat portion 136, oil flows from the lower chamber 20 to the upper chamber 19 via the passage in the outer passage hole 143, the passage between the open secondary valve 171 and the outer valve seat portion 136, the cap chamber 146, the passage in the through hole 161 of the secondary valve 171, the passage in the inner passage hole 141 of the valve seat component 106E, the passage in the notch 241 of the disc 108E, the passage in the large diameter hole 221E of the valve seat component 106E, the passage in the passage notch 30C of the piston rod 21C, the passage in the notch 88 of the disc 82, and the passage hole 37 of the piston 18. These constitute the second passage 172E on the compression side.

[0185] At this time, in addition to the passage within the notch 88 of disc 82 becoming the throttling section 175, the passage within the notch 241 of disc 108E also becomes the throttling section 245. The throttling section 175 and the throttling section 245 allow oil to flow through the second passage 172E, and are arranged in series downstream of the secondary valve 171, which is the flow of oil when the secondary valve 171 is open.

[0186] During the extension stroke, oil flows from the upper chamber 19 to the lower chamber 20 via the passage in the passage hole 37 of the piston 18, the passage in the notch 88 of the disc 82, the passage in the large-diameter bore 46 of the piston 18, the passage in the passage notch 30C of the piston rod 21C, the passage in the large-diameter bore 221E of the valve seat component 106E, the passage in the notch 241 of the disc 108E, and the passage between the auxiliary valve 181E and the valve seat 139. These constitute the second passage 182E on the extension side.

[0187] At this time, in addition to the passage within the notch 88 of disc 82 becoming the throttling section 175, the passage within the notch 241 of disc 108E also becomes the throttling section 245. The throttling sections 175 and 245 allow oil to flow through the second passage 182E, and are arranged in series upstream of the auxiliary valve 181E, which is used for oil flow when the auxiliary valve 181E is open.

[0188] The buffer 1E of the sixth embodiment increases the degree of freedom in setting the throttling section by using two series throttling sections, throttling section 175 and throttling section 245.

[0189] [Seventh Implementation Method]

[0190] Next, mainly based on Figure 13 The seventh embodiment will be described focusing on the differences from the third embodiment. Furthermore, parts common to the third embodiment will be indicated using the same names and reference numerals.

[0191] In the buffer 1F of the seventh embodiment, as Figure 13 As shown, piston 18F has a structure that differs from piston 18B in the third embodiment. The piston body 35F of piston 18F is different from piston body 35B.

[0192] An insertion hole 44F is formed axially through the radial center of the piston body 35F. The insertion hole 44F allows the mounting shaft portion 28 of the piston rod 21 to engage. The piston body 35F is provided with a plurality of (in) connections that allow communication between the upper chamber 19 and the lower chamber 20. Figure 13 (Due to the cross-sectional shape, only one point is shown in the diagram) passageway 37F, and multiple (in) passageways that connect the upper chamber 19 and the lower chamber 20. Figure 13 (Due to the cross-sectional view, only one passage hole 39F is shown.) The piston body 35F is a sintered product. On the piston body 35F, passage holes 37F and 39F are formed during sintering or by cutting with a drill bit.

[0193] Multiple passage holes 37F are parallel to the axis of the piston body 35F. Multiple passage holes 39F are also parallel to the axis of the piston body 35F.

[0194] At the axial end of the piston body 35F on the lower chamber 20 side, an annular inner seat portion 47F is formed on the radially inner side of the opening on the lower chamber 20 side of the passage hole 37F. A valve seat portion 48F is formed at the axial end of the piston body 35F on the lower chamber 20 side, and the valve seat portion 48F and the inner seat portion 47F annularly surround the respective lower chamber 20 side opening of the passage hole 37F.

[0195] At the axial end of the piston body 35F on the upper chamber 19 side, an annular inner seat portion 49F is formed on the radially inner side of the opening on the upper chamber 19 side of the passage hole 39F. A valve seat portion 50F is formed at the axial end of the piston body 35F on the upper chamber 19 side, and the valve seat portion 50F and the inner seat portion 49F annularly surround the respective upper chamber 19 side opening of the passage hole 39F.

[0196] At the axial end of the piston body 35F on the lower chamber 20 side, a stepped portion 251 is formed at the opening position of each of the circumferential passage holes 39F, positioned axially inward compared to the inner seat portion 47F. The stepped portion 251 ensures that the corresponding passage holes 39F are always connected to the lower chamber 20. At the axial end of the piston body 35F on the upper chamber 19 side, a stepped portion 252 is formed at the opening position of each of the circumferential passage holes 37F, positioned axially inward compared to the inner seat portion 49F. The stepped portion 252 ensures that the corresponding passage holes 37F are always connected to the upper chamber 19.

[0197] In the seventh embodiment, a main valve 71F with a structure different from that of the main valve 71 is provided on a compression side. The main valve 71F has a disc 63F positioned at a predetermined midpoint in the stacking direction of the plurality of discs 63. A protrusion 255 is formed on the radially outer side of the disc 63F, protruding axially. The protrusion 255 protrudes toward the valve seat portion 50F. The protrusion 255 presses the outer periphery of one of the discs 63 located closer to the valve seat portion 50F than the disc 63F against the valve seat portion 50F. The main valve 71F always abuts against the inner seat portion 49F, moving away from and settling relative to the valve seat portion 50F. The main valve 71F and the valve seat portion 50F constitute the first damping force generating mechanism 42F on the compression side.

[0198] In the seventh embodiment, a main valve 91F is provided with an extension side having a structure different from that of the main valve 91. The main valve 91F has a disc 83F positioned at a predetermined midpoint in the stacking direction of the plurality of discs 83. A protrusion 256 protruding axially is formed on the radially outer side of the disc 83F. The protrusion 256 protrudes toward the valve seat portion 48F. The protrusion 256 presses the outer periphery of one of the discs 83 located closer to the valve seat portion 48F than the disc 83F against the valve seat portion 48F. The main valve 91F always abuts against the inner seat portion 47F, moving away from and settling relative to the valve seat portion 48F. The main valve 91F and the valve seat portion 48F constitute the first damping force generating mechanism 41F.

[0199] In the seventh embodiment, the passage between the main valve 71F and the valve seat portion 50F that appears during the valve opening in the compression stroke, the passage within the passage hole 39F, and the passage within the step portion 251 constitute the first passage 72F on the compression side. The passage between the main valve 91F and the valve seat portion 48F that appears during the valve opening in the extension stroke, the passage within the passage hole 37F, and the passage within the step portion 252 constitute the first passage 92F on the extension side.

[0200] [Eighth Implementation Method]

[0201] Next, mainly based on Figure 14 The eighth embodiment will be described focusing on the parts that differ from the third embodiment. Furthermore, parts common to the third embodiment will be indicated using the same names and reference numerals.

[0202] In the buffer 1G of the eighth embodiment, such as Figure 14 As shown, piston 18G has a structure and part that differ from piston 18B in the third embodiment. The structure of piston body 35G of piston 18G is different from that of piston body 35B.

[0203] An insertion hole 44G is formed axially through the radial center of the piston body 35G. The insertion hole 44G engages the mounting shaft portion 28 of the piston rod 21B. The piston body 35G is provided with multiple passage holes 37G and multiple passage holes 39G that connect the upper chamber 19 and the lower chamber 20. The piston body 35G is a sintered product. The passage holes 37G and 39G on the piston body 35G are formed during sintering or by cutting using a drill bit.

[0204] Multiple through holes 37G extend axially parallel to the piston body 35G. Multiple through holes 39G also extend axially parallel to the piston body 35G. Multiple through holes 37G are formed radially inside the piston body 35G compared to multiple through holes 39G.

[0205] A recess 261 is formed radially at the center of the end of the piston body 35G on the axial side of the lower chamber 20. The recess 261 is recessed toward the axial side of the upper chamber 19. At the bottom of the recess 261, an annular inner seat 47G is formed radially inside the opening of the piston body 35G on the lower chamber 20 side of the passage hole 37G. At the bottom of the recess 261, an annular valve seat 48G is formed radially outside the opening of the piston body 35G on the lower chamber 20 side of the passage hole 37G and radially inside the opening of the piston body 35G on the lower chamber 20 side of the passage hole 39G.

[0206] At the axial end of the piston body 35G on the upper chamber 19 side, an annular inner seat portion 49G is formed radially inner to the opening of the piston body 35G on the upper chamber 19 side of the passage hole 37G. At the axial end of the piston body 35G on the upper chamber 19 side, an annular intermediate valve seat portion 265 is formed radially outer to the opening of the piston body 35G on the upper chamber 19 side of the passage hole 37G and radially inner to the opening of the piston body 35G on the upper chamber 19 side of the passage hole 39G. At the axial end of the piston body 35G on the upper chamber 19 side, an annular outer valve seat portion 50G is formed radially outer to the opening of the piston body 35G on the upper chamber 19 side of the passage hole 39G.

[0207] In the eighth embodiment, a compression-side main valve 71G is provided instead of the main valve 71. The main valve 71G is composed of multiple (specifically two) discs 63G. The main valve 71G is always in contact with the inner seat 49G and can be disengaged from and seated against the intermediate valve seat 265 and the outer valve seat 50G. The main valve 71G opens and closes the passage in the passage hole 39G on the compression side. The intermediate valve seat 265 and the outer valve seat 50G, together with the main valve 71G, constitute the second damping force generating mechanism 42G on the compression side.

[0208] On the axial side of the main valve 71G opposite to the piston 18G, there are multiple (specifically two) discs 65G with an outer diameter smaller than the outer diameter of the main valve 71G. On the axial side of the discs 65G opposite to the main valve 71G, there is an annular member 67G. The outer diameter of the annular member 67G is the same as the outer diameter of the main valve 71G, and it abuts against the shaft step portion 29. The annular member 67G restricts the deformation of the main valve 71G in the opening direction by a predetermined amount. In the disc 63G, a through hole 267 is formed between the intermediate valve seat portion 265 and the inner seat portion 49G. On the disc 65G, through holes 268 are also formed radially, aligned with the through hole 267. These through holes 267 and 268 ensure that the passage in the passage hole 37G is always connected to the upper chamber 19.

[0209] In the eighth embodiment, a main valve 91G with an extended side is provided instead of the main valve 91. The main valve 91G is composed of a plurality of (specifically five) discs 83G. The main valve 91G is always in contact with the inner seat 47G and can be disengaged and seated against the valve seat 48G. The main valve 91G opens and closes the passage in the passage hole 37G on the extended side. The side of the main valve 91G opposite to the piston 18G abuts against the disc 84.

[0210] In the eighth embodiment, the passage between the main valve 71G and the outer valve seat portion 50G that appears during the valve opening in the compression stroke, and the passage within the passage hole 39G, constitute the first passage 72G on the compression side. Furthermore, the passage between the main valve 91G and the valve seat portion 48G that appears during the valve opening in the extension stroke, the passage within the passage hole 37G, and the passage within the through holes 267 and 268 constitute the first passage 92G on the extension side.

[0211] The bottom 122 and intermediate cone 123, which are configured with the main valve 91G, disc 84, disc 85, cap component 101, are inserted into the recess 261 of the piston body 35G of the piston 18G. As a result, the overall axial length of the component mounted on the mounting shaft 28 of the piston rod 21B is shortened.

[0212] [Ninth Implementation Method]

[0213] Next, mainly based on Figure 15 The ninth embodiment will be described focusing on the differences from the third embodiment. Furthermore, parts common to the third embodiment will be indicated using the same names and reference numerals.

[0214] In the buffer 1H of the ninth embodiment, as Figure 15 As shown, piston 18H has a structure different from piston 18B in the third embodiment. The structure of piston body 35H of piston 18H is different from piston body 35.

[0215] An insertion hole 44H is formed axially through the radial center of the piston body 35H. The insertion hole 44H allows the mounting shaft portion 28 of the piston rod 21 to engage. The piston body 35H is provided with a plurality of (in) connections that allow communication between the upper chamber 19 and the lower chamber 20. Figure 15 (Due to the cross-sectional shape, only one passage hole 37H is shown in the diagram, which connects the upper chamber 19 and the lower chamber 20.) Figure 15 (Due to the cross-sectional shape, only one passage hole 39H is shown in the diagram.) The piston body 35H has passage holes 37H and 39H formed by machining.

[0216] The multiple passage holes 37H are generally straight. The multiple passage holes 37H are axially inclined relative to the piston body 35H. The multiple passage holes 39H are also generally straight. The multiple passage holes 39H are also axially inclined relative to the piston body 35H. The upper chamber 19 side of the multiple passage holes 37H is located radially outward of the piston body 35H compared to the lower chamber 20 side. The lower chamber 20 side of the multiple passage holes 39H is located radially outward of the piston body 35H compared to the upper chamber 19 side. The piston body 35H has a shape without a distinct front and back surface, and its shape is the same regardless of its axial orientation when mounted on the piston rod 21.

[0217] At the axial end of the piston body 35H on the lower chamber 20 side, an annular inner seat portion 47H is formed radially inward to the inner side of the opening on the lower chamber 20 side of the passage hole 37H. At the axial end of the piston body 35H on the lower chamber 20 side, an annular valve seat portion 48H is formed radially outward to the outer side of the opening on the lower chamber 20 side of the passage hole 37H. The inner seat portion 47H is recessed axially inward to the inner side of the piston body 35H compared to the valve seat portion 48H.

[0218] At the axial end of the piston body 35H on the upper chamber 19 side, an annular inner seat portion 49H is formed on the radially inner side of the opening on the upper chamber 19 side of the passage hole 39H. At the axial end of the piston body 35H on the upper chamber 19 side, an annular valve seat portion 50H is formed on the radially outer side of the opening on the upper chamber 19 side of the passage hole 39H.

[0219] In the ninth embodiment, a second damping force generating mechanism 42H is provided, which has a structure that differs from the second damping force generating mechanism 42. The second damping force generating mechanism 42H has a main valve 71H, which differs from the main valve 71 in that it has multiple (specifically three) discs 62.

[0220] In the ninth embodiment, a first damping force generating mechanism 41H is provided, with a structure different from that of the first damping force generating mechanism 41B. The first damping force generating mechanism 41H has a main valve 91H. The main valve 91H differs from the main valve 91 in that it has multiple (specifically two) discs 82H on the side of disc 82B opposite to disc 83. The side of disc 82H opposite to disc 82B abuts against the inner seat portion 47H. The outer diameter of disc 82H is smaller than the outer diameter of disc 82B.

[0221] In the ninth embodiment, the passage between the main valve 71H and the valve seat portion 50H that appears during the valve opening in the compression stroke, and the passage within the passage hole 39H, constitute the first passage 72H on the compression side. Furthermore, the passage between the main valve 91H and the valve seat portion 48H that appears during the valve opening in the extension stroke, and the passage within the passage hole 37H, constitute the first passage 92H on the extension side.

[0222] Furthermore, in the seventh to ninth embodiments, the changes relative to the third embodiment were described as examples, but any of the constructions in the seventh to ninth embodiments can be applied to the first, second, fourth to sixth embodiments.

[0223] Furthermore, the above embodiments show an example of applying the present invention to a multi-cylinder hydraulic buffer, but it is not limited thereto. It can also be used to a single-cylinder hydraulic buffer in which a gas chamber is formed on the side opposite to the upper chamber 19 of the lower chamber 20 in the cylinder 2 without an outer cylinder, and can also be used to various buffers including pressure control valves that use a packing valve with a structure in which a sealing element is provided on the disc.

[0224] According to a first embodiment described above, the buffer includes: a cylinder containing a working fluid; a piston slidably disposed within the cylinder, dividing the cylinder into a side chamber and a side chamber; a piston rod connected to the piston and extending outward from the cylinder; a first passage and a second passage for the working fluid to flow from the upstream chamber to the downstream chamber within the cylinder by movement of the piston; a first damping force generating mechanism disposed in the first passage on the piston to generate a damping force; and a second damping force generating mechanism disposed in an annular valve seat member disposed in the other side chamber and in the second passage parallel to the first passage to generate a damping force. The second damping force generating mechanism includes: a first auxiliary valve disposed on one side of the second passage on the valve seat member and a second auxiliary valve disposed on the other side; and a bottomed cylindrical cap member disposed between the piston and the valve seat member in the second passage. The valve seat component is disposed within the cap component, the first auxiliary valve is disposed in the other side chamber, and the second auxiliary valve is disposed in the cap chamber between the bottom of the cap component and the valve seat component. In the second passage, a throttling section is disposed upstream or downstream of the flow where the first auxiliary valve is open. In the region where the piston speed is low, the second damping force generating mechanism is open when the first damping force generating mechanism is closed; in the region where the piston speed is greater than low speed, both the first and second damping force generating mechanisms are open. This improves the valve's durability.

[0225] The second approach is that, in the first approach, the second path is not a path that is always connected.

[0226] The third method is that, in the first or second method, the piston rod is inserted into the piston, the cap component, and the valve seat component.

[0227] The fourth method is, in any of the first to third methods, where the throttling section is formed by cutting the disc in the first damping force generating mechanism that abuts against the piston.

[0228] The fifth method is that, in any of the first to fourth methods, the second passage is formed by cutting the piston rod.

[0229] The sixth method is that, in any of the first to fifth methods, the second auxiliary valve, which serves as the inflow valve into the cap chamber, has a lower opening pressure than the first auxiliary valve.

[0230] The seventh method is to make the cap component a stamped component in any of the first to sixth methods.

[0231] Industrial availability

[0232] The aforementioned buffer can improve the durability of the valve.

[0233] Explanation of reference numerals in the attached figures

[0234] 1. 1A~1H buffer

[0235] 2 cylinders

[0236] Pistons 18, 18B, 18F~18H

[0237] 19. Upper Room (Side Room)

[0238] 20. Lower chamber (other side chamber)

[0239] 21, 21B Piston Rod

[0240] 41, 41B, 41F~41H First damping force generating mechanism

[0241] 42, 42B, 42F~42H First damping force generating mechanism

[0242] 72, 72F~72H First Pathway

[0243] 92, 92F~92H First Pathway

[0244] 101, 101C, 101E Cap Components

[0245] Valve seat components 106, 106C~106E

[0246] Bottom of 122, 122C, 122E

[0247] 146 Hat Room

[0248] 171, 171D Secondary Valve

[0249] 172, 172A~172E Second Pathway

[0250] 173, 173D Second Damping Force Generating Mechanism

[0251] 175, 175B, 175D, 245 Throttling section

[0252] 181, 181E Secondary Valve (First Secondary Valve)

[0253] Second pathways 182, 182A~182E

[0254] 183, 183E Second Damping Force Generating Mechanism

Claims

1. A buffer, characterized in that, have: The cylinder block, which contains the working fluid; A piston that is slidably disposed within the cylinder, dividing the cylinder into a side chamber and a side chamber; A piston rod, which is connected to the piston and extends outward from the cylinder; The first passage and the second passage allow the working fluid to flow from the upstream chamber to the downstream chamber within the cylinder body through the movement of the piston. A first damping force generating mechanism is provided in the first passage provided on the piston to generate a damping force; as well as The second damping force generating mechanism, which is located in the annular valve seat component disposed in the other side chamber, and is located in the second passage parallel to the first passage, generates a damping force. The second damping force generating mechanism includes: A first auxiliary valve disposed on one side of the second passage provided in the valve seat component and a second auxiliary valve disposed on the other side; and A bottomed cylindrical cap component is disposed between the piston and the valve seat component in the second passage; The valve seat component is disposed within the cap component, the first auxiliary valve is disposed in the other side chamber, and the second auxiliary valve is disposed in the cap chamber between the bottom of the cap component and the valve seat component. In the second passage, a throttling section is provided on the upstream or downstream side of the flow when the first auxiliary valve is opened. In the region where the piston speed is low, with the first damping force generating mechanism in a closed state, the second damping force generating mechanism opens its valve. In the speed range where the piston speed is greater than the low speed, both the first damping force generating mechanism and the second damping force generating mechanism open their valves.

2. The buffer according to claim 1, characterized in that, The second path is not always connected.

3. The buffer according to claim 1 or 2, characterized in that, The piston rod is inserted into the piston, the cap component, and the valve seat component.

4. The buffer according to claim 1 or 2, characterized in that, The throttling section is formed by cutting the disc that abuts against the piston in the first damping force generating mechanism.

5. The buffer according to claim 1 or 2, characterized in that, The second passage is formed by cutting the piston rod.

6. The buffer according to claim 1 or 2, characterized in that, The second auxiliary valve, which acts as an inflow valve into the cap chamber, has a lower opening pressure compared to the first auxiliary valve.

7. The buffer according to claim 1 or 2, characterized in that, The cap component is made into a stamped component.

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