Buffer device

Abstract

This shock-absorbing device is provided with: a first valve provided in a first flow path; a first decompression flow path into which the fluid flows from the first chamber and which decompresses the pressure of the fluid at a first intensity; a second pressure-reducing flow path provided in parallel with the first flow path and having a smaller cross-sectional area than the first pressure-reducing flow path; a third pressure-reducing flow path provided in parallel with the second pressure-reducing flow path, the third pressure-reducing flow path having a smaller cross-sectional area than the first pressure-reducing flow path and a larger cross-sectional area than the second pressure-reducing flow path; a pressure chamber which is located on the downstream side of the second pressure-reducing flow path and which can apply a pressure in the valve-closing direction, which is generated by the fluid, to the first valve; a volume change mechanism which is provided in the pressure chamber, deforms according to the internal pressure of the pressure chamber, and changes the volume of the pressure chamber by means of the internal pressure; and a second valve which is provided in parallel with the third pressure-reducing flow path and which enables the flowing-in fluid to flow to the downstream second chamber.

Description

Technical Field

[0001] This invention relates to a buffer device.

[0002] This application claims priority based on Japanese Patent Application No. 2023-165934 filed on September 27, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] As a buffer device, there is a buffer device that can change the damping force by sensing the frequency (for example, see Patent Document 1 below).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-55850 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] In a buffer device, it is required to mitigate changes in attenuation characteristics.

[0009] Therefore, the technical problem of the present invention is to provide a buffer device capable of mitigating changes in attenuation characteristics.

[0010] Technical solutions for solving technical problems

[0011] One aspect of the present invention provides a buffer device comprising: a cylindrical body; a dividing member that divides the interior of the cylindrical body into a first chamber and a second chamber; a first flow path that connects the first chamber to the second chamber; a first valve disposed in the first flow path; a first pressure-reducing flow path that allows fluid to flow into the first chamber and reduces the pressure of the fluid by a first intensity; a second pressure-reducing flow path disposed in parallel with the first flow path and having a smaller cross-sectional area than the first pressure-reducing flow path; a third pressure-reducing flow path disposed in parallel with the second pressure-reducing flow path, having a smaller and larger cross-sectional area than both the first and second pressure-reducing flow paths; a pressure chamber located downstream of the second pressure-reducing flow path, capable of applying a pressure in the closing direction generated by the fluid to the first valve; a volume change mechanism disposed in the pressure chamber that deforms according to the internal pressure of the pressure chamber, causing a volume change in the pressure chamber; and a second valve disposed in parallel with the third pressure-reducing flow path, capable of allowing the incoming fluid to flow into the second chamber, which is downstream.

[0012] Another aspect of the present invention provides a buffer device, comprising: a bottomed cylindrical body; a piston dividing the interior of the cylindrical body into a first chamber and a second chamber; a rod fixing the piston; and a valve structure having: a first flow path communicating upstream of the first chamber to the second chamber, which is downstream; a first valve disposed in the first flow path, having a first valve seat and a first valve core seated on or away from the first valve seat; a pressure chamber capable of applying pressure to the first valve core generated by fluid in the valve-closing direction; a second flow path, at least a portion of which is disposed parallel to the first flow path and communicating upstream of the first chamber to the second chamber, which is downstream; a second valve disposed in the second flow path, comprising a second valve seat and a second valve core seated on or away from the second valve seat; and a connecting passage communicating from the inside of the second valve seat, which is upstream, to the pressure chamber, which is downstream.

[0013] Invention Effects

[0014] Based on the methods described above, a buffer device capable of mitigating changes in attenuation characteristics can be provided. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating a buffer device according to a first embodiment of the present invention, and is a cross-sectional view viewed in a section including its central axis CL.

[0016] Figure 2 This is a diagram showing the valve structure of a buffer device. Figure 1 A partially enlarged sectional view of part A.

[0017] Figure 3 This is a bottom view showing the pilot housing of the same buffer device.

[0018] Figure 4 This diagram shows a modified example of the valve structure of the same buffer device, and is related to... Figure 2 A partially enlarged sectional view of the part corresponding to section B.

[0019] Figure 5 This is a hydraulic circuit diagram representing the valve structure of the buffer device.

[0020] Figure 6 This is a hydraulic circuit diagram representing the valve opening control mechanism of the buffer device.

[0021] Figure 7 It is a characteristic curve diagram showing the damping force of the valve structure of the same buffer device relative to the piston speed.

[0022] Figure 8 This is a diagram showing the valve structure of the buffer device according to the second embodiment of the present invention, which is equivalent to... Figure 1A partially enlarged sectional view of part A.

[0023] Figure 9 This is a diagram showing the low-speed damping force generation part of the same buffer device. Figure 8 A partially enlarged sectional view of part C.

[0024] Figure 10 This is a hydraulic circuit diagram representing the valve structure of the buffer device.

[0025] Figure 11 This is a diagram showing the valve structure of the buffer device according to the third embodiment of the present invention, which is equivalent to... Figure 1 A partially enlarged sectional view of part A.

[0026] Figure 12 This is a diagram showing the valve opening control mechanism of the same buffer device. Figure 11 A partially enlarged sectional view of part D.

[0027] Figure 13 This is a hydraulic circuit diagram representing the valve structure of the buffer device.

[0028] Figure 14 It is a characteristic curve diagram showing the damping force of the valve structure of the same buffer device relative to the piston speed. Detailed Implementation

[0029] [First Implementation]

[0030] based on Figures 1 to 7 The first embodiment of the present invention will be described below. It should be noted that, for ease of explanation, the following will be... Figure 1 , Figure 2 , Figure 4 , Figure 8 , Figure 9 , Figure 11 and Figure 12 The top of the paper is set to "top", and... Figure 1 , Figure 2 , Figure 4 , Figure 8 , Figure 9 , Figure 11 and Figure 12 The bottom of the paper in the diagram is marked "bottom" for explanation. Additionally, in some figures, the central axis CL of the buffer device 1 is sometimes shown.

[0031] like Figure 1As shown, the buffer device 1 of the first embodiment is a so-called multi-cylinder type hydraulic buffer, comprising a bottomed cylindrical body 2 sealed with oil L as a fluid. The cylindrical body 2 has: a cylindrical inner cylinder 3; a bottomed cylindrical outer cylinder 4, which is concentrically arranged with the inner cylinder 3 such that it covers the inner cylinder 3 with a diameter larger than that of the inner cylinder 3; and a cover 5, which is provided to cover the upper opening side of the outer cylinder 4. An oil storage chamber 6 is formed between the inner cylinder 3 and the outer cylinder 4. It should be noted that, as described above, the buffer device 1 of the first embodiment is multi-cylinder type, but the scope of the present invention can be applied to single-cylinder type or three-layer cylindrical type, etc., and is not limited thereto.

[0032] The outer cylinder 4 is composed of a cylindrical body component 11 and a bottom component 12 that closes the lower part of the body component 11. The bottom component 12 is welded to the body component 11 around its entire circumference while fitting into the lower side of the body component 11. Thus, the bottom component 12 is fixed to the lower side of the body component 11. A mounting ring 13 is fixed to the bottom component 12 on the outer side opposite to the body component 11.

[0033] The cover 5 has a cylindrical portion 15 and an inner flange portion 16 extending radially inward from the upper end of the cylindrical portion 15. The cover 5 covers the body component 11 in such a way that the inner flange portion 16 covers the upper opening of the body component 11 and the cylindrical portion 15 covers the outer peripheral surface of the body component 11. In this state, a portion of the cylindrical portion 15 is pressed inward in the radial direction and fixed to the body component 11.

[0034] The buffer device 1 includes a piston 18 (dividing component). The piston 18 is slidably fitted into the inner cylinder 3 of the cylinder body 2. The piston 18 divides the interior of the inner cylinder 3 of the cylinder body 2 into a first chamber 19 and a second chamber 20. Oil L, as a fluid, is sealed in the first chamber 19 and the second chamber 20 within the inner cylinder 3, and oil L and gas G, as fluids, are sealed in the oil storage chamber 6 between the inner cylinder 3 and the outer cylinder 4. It should be noted that the fluid used is not particularly limited.

[0035] The buffer device 1 includes a rod 21. One end of the rod 21 is disposed inside the inner cylinder 3 of the cylinder 2 and fixed to the piston 18, while the other end extends to the outside of the cylinder 2. The piston 18 and the rod 21 move as a unit. During the extension stroke of the rod 21, which increases its protrusion from the cylinder 2, the piston 18 moves toward the first chamber 19. During the retraction stroke of the rod 21, which decreases its protrusion from the cylinder 2, the piston 18 moves toward the second chamber 20.

[0036] A rod guide 22 is fitted into the upper opening side of the inner cylinder 3 and the outer cylinder 4. In the outer cylinder 4, a sealing member 23 is assembled on the upper side, closer to the outer side of the cylinder 2 than the rod guide 22. A friction member 24 is provided between the rod guide 22 and the sealing member 23. The rod guide 22, the sealing member 23, and the friction member 24 are all annular. The rod 21 can slide through the inner side of each of these rod guides 22, friction members 24, and sealing members 23, and extends from the inside of the cylinder 2 to the outside.

[0037] The rod guide 22 restricts the radial movement of the rod 21 while simultaneously supporting the rod 21 axially, guiding its movement. The sealing member 23 seals against the outer cylinder 4 at its outer periphery and slides against the outer periphery of the axially moving rod 21 at its inner periphery, preventing leakage of oil L from the inner cylinder 3 and gas G and oil L from the oil reservoir 6 in the outer cylinder 4 to the outside. The friction member 24 slides against the outer periphery of the rod 21 at its inner periphery, generating frictional resistance in the rod 21.

[0038] The outer periphery of the rod guide 22 is stepped, with the upper diameter larger than the lower diameter. The lower part of the smaller diameter fits into the inner periphery of the upper end of the inner cylinder 3, and the upper part of the larger diameter fits into the inner periphery of the upper part of the outer cylinder 4. A base valve 25 dividing the second chamber 20 and the oil reservoir 6 is provided on the bottom component 12 of the outer cylinder 4, and the inner periphery of the lower end of the inner cylinder 3 is fitted into this base valve 25. A portion (not shown) of the upper end of the outer cylinder 4 is pressed inward in the radial direction; this pressed portion and the rod guide 22 clamp the sealing component 23.

[0039] The rod 21 has a main shaft portion 27 and a mounting shaft portion 28 with an outer diameter smaller than that of the main shaft portion 27. The mounting shaft portion 28 is disposed inside the cylinder 2 to mount the piston 18, etc. The end face of the mounting shaft portion 28 side of the main shaft portion 27 in the axial direction of the rod 21 extends in the orthogonal direction of the axis.

[0040] like Figure 2 As shown, on the outer periphery of the mounting shaft portion 28, a passage groove 29, a passage groove 30, and a passage groove 31 are formed at the middle position in the axial direction.

[0041] The passageway 29 is formed around the entire circumference of the mounting shaft portion 28 and is in the shape of a ring.

[0042] The passage groove 30 is formed around the entire circumference of the mounting shaft portion 28 and is annular. The passage groove 30 is located on the opposite side of the main shaft portion 27 in the axial direction of the mounting shaft portion 28, which is closer to the main shaft portion 27 than the passage groove 29.

[0043] The passageway 31 extends axially along the mounting shaft portion 28, connecting the passageway 29 and the passageway 30. The passageway in the passageway 31 connects the passageway in the passageway 29 and the passageway in the passageway 30.

[0044] It should be noted that the passage slots 29 to 31 can also be achieved by making the interior of rod 21B hollow.

[0045] On the outer periphery of the mounting shaft portion 28, a male thread 32 is formed at the front end of the mounting shaft portion 28 on the opposite side of the main shaft portion 27 to the passage groove 30 in the axial direction.

[0046] In buffer device 1, for example, Figure 1 The rod 21 shown has its protruding portion from the cylinder 2 positioned at the top and supported by the vehicle body, while the mounting ring 13 on the side of the cylinder 2 is positioned at the bottom and connected to the wheel side. Alternatively, the cylinder 2 can be supported by the vehicle body, and the rod 21 can be connected to the wheel side. When the wheel vibrates during driving, the relative positions of the cylinder 2 and the rod 21 change with this vibration, and this change is suppressed by the fluid resistance of the flow path formed in at least one of the piston 18 and the rod 21. As described in detail below, the fluid resistance of the flow path formed in at least one of the piston 18 and the rod 21 varies depending on the speed or amplitude of the vibration, thereby improving ride comfort by suppressing vibration. Between the cylinder 2 and the rod 21, in addition to the vibration generated by the wheel, inertial forces and centrifugal forces generated by the vehicle body during driving also act. For example, when the steering wheel is operated, the driving direction changes, thereby generating centrifugal force in the vehicle body, and a force based on this centrifugal force acts between the cylinder 2 and the rod 21. As explained below, the buffer device 1 has excellent characteristics against vibrations caused by forces generated on the vehicle body as the vehicle moves, resulting in high stability during vehicle operation.

[0047] like Figure 2 As shown, the piston 18 consists of a metal piston body 33 supported on the rod 21 and an annular sliding component 34 integrally assembled on the outer circumferential surface of the piston body 33 and sliding within the inner cylinder 3.

[0048] Multiple (in) are formed on the piston body 33. Figure 2 (Due to the cross-sectional shape, only one is shown in the diagram) A passage hole 35 and an annular passage groove 36 connecting the ends of these passage holes 35 opposite to the first chamber 19. Additionally, multiple (in...) are formed on the piston body 33. Figure 2 (Due to the cross-sectional shape, only one passage hole is shown in the diagram) and an annular passage groove 38 that connects the ends of these passage holes 37 to the first chamber 19 side. Multiple passage holes 35 are formed in the circumferential direction of the piston body 33, with one passage hole 37 sandwiched in the middle.

[0049] The passages in the multiple passage holes 35 and the passage grooves 36 constitute a piston passage 39 that passes through the piston 18 axially and connects the first chamber 19 and the second chamber 20. The passages in the multiple passage holes 37 and the passage grooves 38 constitute a piston passage 40 that passes through the piston 18 axially and connects the first chamber 19 and the second chamber 20.

[0050] A valve mechanism 41 (first valve) is provided in the piston passage 39 to generate damping force by opening and closing the piston passage 39. The valve mechanism 41 is disposed on one end side of the piston 18 in the axial direction, i.e., the second chamber 20 side, and is mounted on the rod 21. By disposing of the valve mechanism 41 on the second chamber 20 side, during the movement of the piston 18 toward the first chamber 19 side, i.e., the extension stroke, the piston passage 39 allows the oil L flowing from the first chamber 19 to flow toward the second chamber 20. The valve mechanism 41 provided in the piston passage 39 becomes a valve mechanism on the extension side that generates damping force by inhibiting the flow of oil L from the extension side of the piston passage 39 to the second chamber 20.

[0051] A valve mechanism 42 is provided in the piston passage 40 to generate damping force by opening and closing the piston passage 40. The valve mechanism 42 is disposed on the other end side of the piston 18 axially, i.e., the first chamber 19 side, and is mounted on the rod 21. With the valve mechanism 42 disposed on the first chamber 19 side, during the movement of the piston 18 towards the second chamber 20 side, i.e., the contraction stroke, the oil L flowing out of the second chamber 20 flows towards the first chamber 19. The valve mechanism 42 provided in the piston passage 40 becomes a contraction-side valve mechanism that generates damping force by inhibiting the flow of oil L from the contraction side of the piston passage 40 to the first chamber 19.

[0052] Through the above, piston passage 39 and piston passage 40 are connected in such a way that oil L, as a fluid, flows between the first chamber 19 and the second chamber 20 through the movement of piston 18. When piston rod 21 and piston 18 move to the extension side, oil L passes through piston passage 39, and when piston rod 21 and piston 18 move to the contraction side, oil L passes through piston passage 40.

[0053] The piston body 33 is composed of two components: a first component 601 and a second component 602. The first component 601 forms the portion of the piston body 33 on the axial side of the second chamber 20, and the second component 602 forms the portion of the piston body 33 on the axial side of the first chamber 19.

[0054] The first component 601 is formed in a generally circular plate shape, and a through hole 604 is formed in the center of its radial direction. The through hole 604 extends through the first component 601 along the axial direction for inserting the mounting shaft portion 28 of the rod 21. The through hole 604 has a small-diameter hole portion 605 on one axial side for engaging the mounting shaft portion 28 of the rod 21, and a large-diameter hole portion 606 on the other axial side with an inner diameter larger than that of the small-diameter hole portion 605.

[0055] In the axial direction of the first component 601, a large-diameter bore 606 is provided on the side closer to the second component 602 than the small-diameter bore 605. A passage groove 607 extending radially along the first component 601 is formed on the end face of the second component 602 side in the axial direction of the first component 601. A passage within the passage groove 607 connects the piston passage 39 and the passage within the large-diameter bore 606. The passage within the passage groove 607 serves as a throttling orifice 608 (first pressure-reducing flow path) that narrows the flow path between the piston passage 39 and the passage within the large-diameter bore 606 to reduce pressure.

[0056] The aforementioned passage groove 36 is formed at the end of the first component 601 on the second chamber 20 side in the axial direction. At the end of the first component 601 on the second chamber 20 side in the axial direction, an annular valve seat portion 47 (first valve seat) forming part of the valve mechanism 41 is formed radially outward from the opening on the second chamber 20 side of the passage groove 36. Furthermore, at the end of the piston body 33 on the second chamber 20 side in the axial direction, an inner seat portion 48 is formed radially inward from the opening on the second chamber 20 side of the passage groove 36. The large-diameter hole portion 606 of the through hole 604 is provided on the side opposite to the valve seat portion 47 and the inner seat portion 48 in the axial direction of the first component 601, compared to the small-diameter hole portion 605.

[0057] The second component 602 is formed in a generally circular plate shape, and a fitting hole 611 is formed in the center of its radial direction. The fitting hole 611 is axially through and is used to fit the mounting shaft portion 28 of the rod 21.

[0058] The aforementioned passage groove 38 is formed at the end of the second component 602 on the side of the first chamber 19 in the axial direction. At the end of the second component 602 on the side of the first chamber 19 in the axial direction, an annular valve seat portion 49, which forms part of the valve mechanism 42, is formed on the outer side of the opening on the first chamber 19 side of the passage groove 38 in the radial direction. In addition, at the end of the piston body 33 on the side of the first chamber 19 in the axial direction, an inner seat portion 50 is formed on the inner side of the opening on the first chamber 19 side of the passage groove 38 in the radial direction.

[0059] The first component 601 and the second component 602 are connected in a circumferentially positioned manner to form piston passages 39 and 40. In this state, the sliding member 34 covers the radially outer side of the first component 601 and the second component 602. Thus, the first component 601 and the second component 602 are integrated to form the piston body 33, and the first component 601, the second component 602, and the sliding member 34 are integrated to form the piston 18.

[0060] In the first component 601, the portion of the valve seat 47 on the radial side opposite to the insertion hole 604 forms a step shape with a lower axial height than the valve seat 47. An opening on the second chamber 20 side of the piston passage 40 on the contraction side is disposed in this stepped portion. Similarly, in the second component 602, the portion of the valve seat 49 on the radial side opposite to the fitting hole 611 forms a step shape with a lower axial height than the valve seat 49. An opening on the first chamber 19 side of the piston passage 39 on the extension side is disposed in this stepped portion.

[0061] In piston 18, mounting shaft portion 28 of rod 21 engages with small-diameter bore portion 605 of insertion hole 604 and fitting hole 611. In the axial direction of rod 21, the position of large-diameter bore portion 606 of piston 18 coincides with passage groove 29 of rod 21.

[0062] On the valve seat portion 47 and inner seat portion 48 side of piston 18, sequentially arranged from the axial piston 18 side are a disc 51, a valve disc 52, a pilot valve 53, a pilot housing 56 (partition wall component), multiple valve discs 57, a disc 58, a valve disc 59, multiple valve discs 60, a disc 61, a disc 62, and an annular component 63, which allow the mounting shaft portion 28 of rod 21 to engage with their respective inner sides. Discs 51, 58, 61, 62, valve discs 52, 57, 59, 60, and annular component 63 are formed in a perforated circular plate shape of a certain thickness, capable of engaging the mounting shaft portion 28 of rod 21 on their inner sides. Pilot valve 53 and pilot housing 56 are formed in annular shape, capable of engaging the mounting shaft portion 28 of rod 21 on their inner sides.

[0063] The pilot housing 56 is a bottomed cylindrical shape with a rod insertion through hole 70 formed at its radial center, which extends through the pilot housing 56 axially. The pilot housing 56 has a perforated circular plate-shaped bottom 71, a cylindrical outer cylindrical portion 72 (cylindrical portion) protruding to one side from the outer periphery of the bottom 71 along the axial direction of the bottom 71, and a cylindrical inner cylindrical portion 73 protruding to the same side as the outer cylindrical portion 72 from the inner periphery of the bottom 71 along the axial direction of the bottom 71.

[0064] Additionally, the pilot housing 56 has an inner seat portion 74 that protrudes from the inner periphery of the bottom 71 along the axial direction of the bottom 71 to the side opposite to the inner cylindrical portion 73, an intermediate valve seat portion 75 that protrudes from the radial direction of the bottom 71 to the same side as the inner seat portion 74 along the axial direction of the bottom 71, and an outer valve seat portion 76 (second valve seat) that protrudes from the radial direction of the bottom 71 to the same side as the inner seat portion 74, to the outer side of the intermediate valve seat portion 75 along the axial direction of the bottom 71.

[0065] In the pilot housing 56, the mounting shaft portion 28 of the rod 21 is engaged with the rod insertion through hole 70. At this time, the pilot housing 56 is positioned such that the outer cylindrical portion 72 and the inner cylindrical portion 73 extend from the bottom 71 toward the piston 18 side in the axial direction of the rod 21. In addition, at this time, the pilot housing 56 has an inner seat portion 74, an intermediate valve seat portion 75, and an outer valve seat portion 76 on the side of the second chamber 20 facing the bottom 71 in the axial direction of the rod 21.

[0066] At the bottom 71, a seat 80 and a recess 82 are formed on the outer cylindrical portion 72 and the inner cylindrical portion 73 in the axial direction of the bottom 71. The seat 80 and the recess 82 are formed at a position between the outer cylindrical portion 72 and the inner cylindrical portion 73 in the radial direction of the bottom 71.

[0067] The seat portion 80 is annular, and the outer cylindrical portion 72 and the inner cylindrical portion 73 of the bottom 71 on the axial direction form the seat surface. This seat surface is a planar shape that extends perpendicularly to the central axis of the bottom 71.

[0068] The recess 82 is annular and is located at the center of the radial direction of the seat 80. The recess 82 is axially recessed from the seat surface of the seat 80 towards the bottom 71. The recess 82 has a shape where the depth increases and the width of the bottom 71 decreases in the radial direction. The recess 82... Figure 2 The center can be set to a circular shape, but it does not have to be circular. That is, it is sufficient to set it on at least a portion of the seat 80.

[0069] An outer through hole 87 is formed at the bottom 71, extending axially along the bottom 71. The outer through hole 87 is inclined relative to the central axis of the bottom 71 such that the further away from the recess 82 in the axial direction of the bottom 71, the further outward it is in the radial direction. Figure 3 As shown, a plurality of outer through holes 87 are formed at equal intervals along the circumference of the bottom 71. It should be noted that at least one outer through hole 87 needs to be provided in the bottom 71.

[0070] like Figure 2 As shown, an inner through hole 88 is formed at the bottom 71, extending axially along the bottom 71. (As shown...) Figure 3As shown, a plurality of inner through holes 88 are formed at equal intervals along the circumference of the bottom 71. It should be noted that at least one inner through hole 88 needs to be provided in the bottom 71. The outer through holes 87 are provided on the outer side of the pilot housing 56 in the radial direction, i.e., the radial direction of the bottom 71, compared to the inner through holes 88.

[0071] The inner seat portion 74 is annular. A passage groove 90 is formed in the inner seat portion 74, and the passage groove 90 extends through the inner seat portion 74 in the radial direction. Multiple passage grooves 90 are formed at equal intervals along the circumference of the inner seat portion 74.

[0072] like Figure 2 As shown, the intermediate valve seat portion 75 protrudes from the bottom 71 along the axial direction of the bottom 71 towards the same side as the inner seat portion 74. The protrusion height of the intermediate valve seat portion 75 from the bottom 71 in the axial direction of the bottom 71 is slightly greater than the protrusion height of the inner seat portion 74 from the bottom 71.

[0073] like Figure 3 As shown, the intermediate valve seat portion 75 has a plurality of valve seat constituent portions 91 at equal intervals along the circumference of the pilot housing 56. The plurality of valve seat constituent portions 91 have the same shape and all extend outward in the radial direction from the inner seat portion 74. In this embodiment, the intermediate valve seat portion 75 is provided with a plurality of portions along the circumference of the bottom 71 and has a fan shape, but is not limited to this; for example, it may also be annular.

[0074] The valve seat assembly 91 has a passage groove 94 that extends through the outer portion of the bottom 71 in the radial direction of the bottom 71.

[0075] like Figure 2 As shown, the outer valve seat portion 76 protrudes axially from the bottom 71 towards the same side as the intermediate valve seat portion 75. The axial protrusion height of the outer valve seat portion 76 from the bottom 71 is greater than that of the intermediate valve seat portion 75. Figure 3 As shown, the outer valve seat portion 76 is annular.

[0076] Each of the plurality of valve seat components 91 in the intermediate valve seat portion 75 and the inner seat portion 74 forms an inner passage recess 95. In other words, the inner passage recess 95 is formed by being surrounded by each of the plurality of valve seat components 91 in the intermediate valve seat portion 75 and the inner seat portion 74. The plurality of inner passage recesses 95 are arranged at equal intervals along the circumference of the pilot housing 56. Figure 2 As shown, multiple inner passage recesses 95 are recessed along the axial direction of the pilot housing 56 from the front end face of the protruding side of the inner seat portion 74 and the front end face of the protruding side of the intermediate valve seat portion 75, respectively. The bottom surface of the inner passage recess 95 is formed by the bottom 71.

[0077] like Figure 3 As shown, the passage groove 94 formed in the valve seat component 91 opens into the inner passage recess 95. The inner through hole 88 is formed on the bottom surface of the inner passage recess 95 and opens into the inner passage recess 95.

[0078] The outer valve seat portion 76, the inner valve seat portion 74, and the intermediate valve seat portion 75 form an outer passage recess 96. The outer passage recess 96 is continuous throughout the entire circumference of the pilot housing 56. For example... Figure 2 As shown, the outer passage recess 96 is recessed along the axial direction of the pilot housing 56 from the front end face of the protruding side of the inner seat portion 74, the front end face of the protruding side of the intermediate valve seat portion 75, and the front end face of the protruding side of the outer valve seat portion 76. The bottom surface of the outer passage recess 96 is formed by the bottom 71.

[0079] The passage groove 90 formed in the inner seat portion 74 opens in the outer passage recess 96.

[0080] The outer through hole 87, at its bottom 71, opens outwards from the outer valve seat 76 side in the radial direction of the pilot housing 56. The outer through hole 87 opens within the second chamber 20. The outer through hole 87 does not open within the inner passage recess 95 or the outer passage recess 96. The inner through hole 88 opens within the inner passage recess 95 but not within the outer passage recess 96.

[0081] The rod insertion through hole 70 has a hole body portion 101 disposed on the central axis of the pilot housing 56, and an axial groove 102 recessed outward from the hole body portion 101 in the radial direction toward the pilot housing 56. For example... Figure 3 As shown, a plurality of axial grooves 102 are formed at equal intervals along the circumference of the main bore portion 101 on the pilot housing 56. The positions of the plurality of axial grooves 102 in the circumferential direction of the pilot housing 56 coincide with the corresponding passage grooves 90.

[0082] like Figure 2 As shown, in the rod insertion through hole 70, the mounting shaft portion 28 of the rod 21 is fitted with the hole body portion 101. In the axial direction of the rod 21, the position of the axial groove 102 coincides with the passage groove 30 of the rod 21.

[0083] In the pilot housing 56, the passage in the axial groove 102 communicates with the passages in the passage grooves 29-31 of the rod 21 and the passage in the passage groove 90 of the pilot housing 56. A portion of the mounting shaft portion 28 of the rod 21 is disposed within the pilot housing 56. The passage in the large-diameter bore portion 606 of the piston 18, the passage in the passage grooves 29-31 of the rod 21, and the passage in the axial groove 102 of the pilot housing 56 constitute a rod-side chamber 105 disposed on the side of the rod 21. The rod-side chamber 105 communicates with the piston passage 39 via the throttling orifice 608 in the passage groove 607 of the piston 18. The rod-side chamber 105 communicates with the passage in the outer passage recess 96 via the passage in the passage groove 90 of the pilot housing 56.

[0084] Within the pilot housing 56, a free valve 111 (diaphragm component) is disposed axially opposite to the bottom 71. The free valve 111 is a flexible plate-shaped component. The outer diameter of the free valve 111 is larger than the outer diameter of the radial recess 82 of the bottom 71. Furthermore, the inner diameter of the free valve 111 is smaller than the inner diameter of the radial recess 82 of the bottom 71. In the free valve 111, the inner cylindrical portion 73 of the pilot housing 56 and the mounting shaft portion 28 of the rod 21 extend radially inward.

[0085] As described above, the bottom 71 of the pilot housing 56 has a recess 82 covered by the free valve 111 and a seat 80 abutting against the free valve 111. An outer through hole 87 penetrating the bottom 71 is located at the position of the recess 82. The pilot housing 56 has an inner through hole 88 in the seat 80, which penetrates the bottom 71 and is located on the inner side of the pilot housing 56 in the radial direction, compared to the outer through hole 87.

[0086] The outer through hole 87 formed in the recess 82 at the bottom 71 is positioned radially relative to the free valve 111 at the end of the recess 82 and is axially opposite to it. The free valve 111 closes the outer through hole 87 by making surface contact with the seat 80, and opens the outer through hole 87 by moving away from the seat 80. In addition, the free valve 111 can elastically deform to enter the recess 82, and at this time it also abuts against the periphery of the boundary between the recess 82 and the seat 80 or the entire surface of the recess 82, maintaining the closed state of the outer through hole 87.

[0087] The diameter of the disc 51 is smaller than the inner diameter of the valve seat portion 47 of the piston 18, and its outer diameter is slightly larger than the outer diameter of the inner seat portion 48.

[0088] The outer diameter of the valve disc 52 is slightly larger than the outer diameter of the valve seat portion 47 of the piston 18. The valve disc 52 abuts against the valve seat portion 47, and the opening of the piston passage 39 is opened and closed by separating from and abutting against the valve seat portion 47.

[0089] The pilot valve 53 consists of a metal valve disc 141 and an elastic adhesive component 142 bonded to the valve disc 141. For example, the adhesive component 142 can be made of rubber and bonded to the valve disc 141 by vulcanization.

[0090] The valve disc 141 is formed into a perforated circular plate of a certain thickness that can fit into the mounting shaft portion 28 of the inner fitting rod 21. The outer diameter of the valve disc 141 is slightly larger than the outer diameter of the valve disc 52. The pilot valve 53 abuts against the inner cylindrical portion 73 of the valve disc 52 and the pilot housing 56 in the valve disc 141.

[0091] The adhesive component 142 is adhered to the outer peripheral side of the valve disc 141, axially opposite to the piston 18. The adhesive component 142 has a sealing portion 145 and a support portion 146. Both the sealing portion 145 and the support portion 146 are adhered to the outer peripheral side of the valve disc 141, axially opposite to the piston 18. Additionally, as... Figure 4 As shown, the valve disc 141 may only have a sealing portion 145A, or it may be configured to replace the support portion 146 with a structure consisting of a gasket 149A and a support spring 149B. The sealing portion 145A performs the same function as the sealing portion 145, and the support spring 149B performs the same function as the support portion 146. It should be noted that in this configuration, the pilot housing 56A fixes the support spring 149B, thus resulting in a structure that uses a pilot housing 56A having an inner cylindrical portion 73A that is set lower than the inner cylindrical portion 73, and uses multiple gaskets 149A.

[0092] The sealing part 145 is formed in an annular shape. The sealing part 145 is adhered to the end edge of the outer peripheral side of the valve disc 141. The sealing part 145 extends from the valve disc 141 along the axial direction of the valve disc 141 to the side opposite to the piston 18.

[0093] The support portion 146 is formed in an annular shape. The support portion 146 and the sealing portion 145 are continuously formed on the inner side of the sealing portion 145 in the radial direction of the valve disc 141. Similar to the sealing portion 145, the support portion 146 extends from the valve disc 141 along the axial direction of the valve disc 141 to the side opposite to the piston 18.

[0094] At least one passage groove 148 is formed in the support portion 146, and the passage groove 148 extends through the support portion 146 in the radial direction. The passage groove 148 can be a hole formed in the support portion 146, or a cut groove that extends from the front end of the support portion 146 (the contact portion with the free valve 111 described later) toward the sealing portion 145. The base end of the support portion 146, located on the valve disc 141 side closer to the passage groove 148 and connected to the valve disc 141, is connected to the base end of the sealing portion 145 connected to the valve disc 141. The sealing portion 145 and the support portion 146 of the adhesive member 142 are made of the same raw material and are integrally formed without joints.

[0095] As described above, the sealing portion 145 is integrally connected to the valve disc 141. Furthermore, the support portion 146 is made of the same material as the sealing portion 145 and, like the sealing portion 145, is integrally connected to the valve disc 141. The support portion 146 is connected to the inner portion of the sealing portion 145 in the radial direction of the valve disc 141. Additionally, the support portion 146 extends from the inner side of the sealing portion 145 in the radial direction of the valve disc 141.

[0096] The sealing portion 145 is slidably and liquid-tightly fitted onto the inner circumferential surface of the outer cylindrical portion 72 of the pilot housing 56, consistently sealing the gap between the pilot valve 53 and the outer cylindrical portion 72. In other words, the pilot valve 53 allows the sealing portion 145 to slidably and liquid-tightly fit onto the outer cylindrical portion 72 of the pilot housing 56. At this time, the valve disc 141 covers the opening on the axial side of the outer cylindrical portion 72 of the pilot housing 56 opposite to the bottom 71.

[0097] The front end of the support portion 146 abuts against the free valve 111. The support portion 146 presses the free valve 111 against the seat portion 80. One end of the support portion 146 is connected to the valve disc 141, and the other end abuts against the free valve 111, applying a separating elastic force directly to the valve disc 141 and the free valve 111.

[0098] The support portion 146 is opposite to and abuts against the portion of the free valve 111 that sits on the seat portion 80. In other words, the contact portion of the support portion 146 with the free valve 111 causes the radial position of the free valve 111 to coincide with the portion of the free valve 111 that sits on the seat portion 80. Specifically, the contact portion of the support portion 146 with the free valve 111 causes the radial position of the free valve 111 to coincide with the portion of the free valve 111 that sits on the bottom 71 in the radial direction, which is further inward than the recess 82.

[0099] With the free valve 111 blocking the outer through hole 87, a pressure chamber 151 is formed between the pilot valve 53, the pilot housing 56, and the free valve 111, and a variable chamber 152 is formed between the recess 82 of the pilot housing 56 and the free valve 111. Therefore, these two pressure chambers 151 and variable chamber 152 are separated within the pilot housing 56 by the free valve 111. The pressure chambers 151 and variable chamber 152 are formed by a bottomed cylindrical pilot housing 56 having a bottom 71 and an outer cylindrical portion 72.

[0100] When the free valve 111 is in a state where it abuts against the seat 80 on both its outer and inner circumferences, abuts against the edges of the recess 82 on both its outer and inner circumferences, and is in full contact with the recess 82, it blocks the flow of oil L between the pressure chamber 151 and the variable chamber 152. Conversely, when the free valve 111 is separated from the seat 80 at the bottom 71, it allows the flow of oil L between the pressure chamber 151 and the variable chamber 152. The variable chamber 152 communicates with the second chamber 20 via a passage in the outer through hole 87.

[0101] The support portion 146 of the adhesive member 142 of the pilot valve 53 applies force to bring the free valve 111 abutting against the seat portion 80. When the differential pressure between the pressure chamber 151 and the variable chamber 152 (with the variable chamber 152 being at high pressure) reaches a predetermined level or higher, the free valve 111 moves against the elastic force of the support portion 146 and separates from the seat portion 80. At this time, the free valve 111 is not subjected to force by the support portion 146 and separates from the seat surface on the radially outer side of the recess 82. Depending on the differential pressure, it may also not separate from the seat surface on the radially inner side of the recess 82. The support portion 146 of the pilot valve 53, the free valve 111, and the seat portion 80 and recess portion 82 of the bottom 71 of the pilot housing 56 constitute a check valve 155. The check valve 155 restricts the flow of oil L from the pressure chamber 151 side to the variable chamber 152 side, i.e. the second chamber 20 side, while allowing the flow of oil L from the variable chamber 152 side, i.e. the second chamber 20 side, to the pressure chamber 151 side.

[0102] The valve core of check valve 155, i.e., the entire free valve 111, is not axially fastened or fixed to any component. In other words, free valve 111 can abut against and separate from the support portion 146 of pilot valve 53 and the bottom 71 of pilot housing 56. Free valve 111 is a floating type free valve whose entire structure can move axially. Forces other than hydraulic pressure applied to free valve 111 are exerted solely by the support portion 146 of pilot valve 53, which approaches and separates from the seat portion 80.

[0103] It should be noted that the spring force of the support portion 146 of the pilot valve 53 can also be set in such a way that the free valve 111 always blocks the flow of oil L between the pressure chamber 151 and the variable chamber 152 regardless of the pressure state of the pressure chamber 151 and the variable chamber 152.

[0104] Because a recess 82 is formed at the bottom 71, the free valve 111 can bend under the pressure of the oil L in the pilot housing 56. When the pressure in the pressure chamber 151 is higher than the pressure in the variable chamber 152, the free valve 111 continues to block the communication between the pressure chamber 151 and the variable chamber 152, and simultaneously, as described above, flexes into the recess 82, increasing the volume of the pressure chamber 151 and deforming the variable chamber 152 by decreasing its volume. Furthermore, from this state onward, when the pressure difference between the pressure in the pressure chamber 151 and the variable chamber 152 decreases, the free valve 111 continues to block the communication between the pressure chamber 151 and the variable chamber 152, while reducing the inflow into the recess 82, increasing the volume of the variable chamber 152 and deforming (restoring) the pressure chamber 151 by decreasing its volume.

[0105] The bottom 71 of the pilot housing 56 has an outer through hole 87 that communicates with the pressure chamber 151 on the side of the bottom 71 facing the second chamber 20, which is radially outward from the outer valve seat portion 76. A free valve 111 is provided in the pilot housing 56, which blocks the outer through hole 87 from the inside of the pressure chamber 151 and can change the volume of the pressure chamber 151 by the pressure inside the pressure chamber 151.

[0106] As described above, valve disc 52 can be seated on valve seat portion 47 of piston 18. Valve disc 141 of pilot valve 53 abuts against valve disc 52. Valve disc 141 and valve disc 52 of pilot valve 53 constitute valve component 161 (first valve) seated on or away from valve seat portion 47.

[0107] The valve component 161, which consists of valve disc 52 and valve disc 141, together with the valve seat portion 47 of piston 18, constitutes valve mechanism 41. There is no throttling orifice between valve component 161 and valve seat portion 47 of piston 18.

[0108] When valve component 161 opens by separating its valve disc 52 from valve seat portion 47, the oil L in the first chamber 19 flows to the second chamber 20 via piston passage 39 and the passage between valve component 161 and valve seat portion 47. Piston passage 39 and the passage between valve component 161 and valve seat portion 47 constitute flow path 162 (first flow path). In other words, piston passage 39 and the separated valve component 161 and valve seat portion 47 form flow path 162 through which the fluid oil L flows from one of the first chamber 19 and the second chamber 20, namely the first chamber 19. Flow path 162 is a flow path connecting the first chamber 19 to the second chamber 20, and a flow path from the first chamber 19 towards and through valve mechanism 41.

[0109] The flow path 162 serves as the extension-side flow path for the oil L, which flows from the first chamber 19 to the second chamber 20 during the extension stroke of the piston 18 towards the first chamber 19. The extension-side valve mechanism 41, consisting of the valve seat 47 and the valve component 161, is a valve provided in the flow path 162. The valve component 161 acts in the direction that reduces the cross-sectional area of ​​the flow path 162, thereby inhibiting the flow of oil L and generating a damping force.

[0110] Multiple valve discs 57 have the same outer diameter, which becomes the outer diameter of the intermediate valve seat portion 75 that can be seated in the pilot housing 56. The multiple valve discs 57 constitute a valve component 171 that can be seated in or separate from the intermediate valve seat portion 75. The valve component 171, by abutting against the intermediate valve seat portion 75, blocks the passage within the inner passage recess 95 between the inner seat portion 74 and the intermediate valve seat portion 75. The valve component 171, by separating from the intermediate valve seat portion 75, opens the passage within the inner passage recess 95, communicating with the passage within the outer passage recess 96 between the intermediate valve seat portion 75 and the outer valve seat portion 76.

[0111] The intermediate valve seat portion 75 of the pilot housing 56 and the valve component 171 constitute the valve mechanism 172 (third valve). The passageway 94 of the intermediate valve seat portion 75 becomes a throttling orifice 173 (second pressure-reducing flow path) that connects the passageway in the inner passageway recess 95 to the outer passageway recess 96 even when the valve component 171 is in contact with the intermediate valve seat portion 75. In other words, the throttling orifice 173 ensures that the passageway in the inner passageway recess 95 and the passageway in the outer passageway recess 96 are always connected. The throttling orifice 173 is provided in the valve mechanism 172, but it only functions as a throttling part to reduce pressure by narrowing the flow path between the passageway in the inner passageway recess 95 and the passageway in the outer passageway recess 96 when the valve mechanism 172 is closed; it does not function as a throttling part when the valve mechanism 172 is open. Therefore, in the hydraulic circuit, as... Figure 5 As shown, the throttling orifice 173 is connected in parallel with the valve mechanism 172. The flow path cross-sectional area S2 of the throttling orifice 173 is smaller than the flow path cross-sectional area S1 of the throttling orifice 608.

[0112] During the contraction stroke, the check valve 155 of the valve mechanism 172 opens, allowing the oil L from the second chamber 20 to flow into the pressure chamber 151. When the pressure in the pressure chamber 151 exceeds a specified value, the valve component 171 moves away from the intermediate valve seat 75. Thus, the valve mechanism 172 allows the oil L from the second chamber 20 to flow into the first chamber 19 via the passage in the outer through-hole 87, the pressure chamber 151, the passage in the inner through-hole 88, the passage in the inner passage recess 95, the passage in the outer passage recess 96, the passage in the passage groove 90, the rod-side chamber 105, the throttle orifice 608, and the piston passage 39.

[0113] The outer diameter of the disc 58 is smaller than that of the valve component 171, and is approximately equal to the outer diameter of the inner seat 74 of the pilot housing 56.

[0114] The outer diameter of the valve disc 59 is slightly larger than the outer diameter of the outer valve seat portion 76 of the pilot housing 56. The valve disc 59 abuts against the outer valve seat portion 76, opening and closing the passage in the outer passage recess 96 by separating from and abutting against the outer valve seat portion 76. When the valve disc 59 moves away from the outer valve seat portion 76, the passage in the outer passage recess 96 communicates with the second chamber 20. A cutout portion 175 is formed on the outer peripheral side of the valve disc 59, which traverses the outer valve seat portion 76 in the radial direction.

[0115] Multiple valve discs 60 have the same outer diameter, which is equal to the outer diameter of valve disc 59. Valve disc 59 and multiple valve discs 60 constitute a valve component 176 (second valve core) that can sit on or leave the outer valve seat portion 76. Valve component 176, by abutting against the outer valve seat portion 76, blocks the passage in the outer passage recess 96 between the inner seat portion 74 and the intermediate valve seat portion 75 and the outer valve seat portion 76. Valve component 171, by separating from the outer valve seat portion 76, allows the passage in the outer passage recess 96 to communicate with the second chamber 20.

[0116] The outer valve seat portion 76 of the pilot housing 56 and the valve component 176 constitute the valve mechanism 178 (second valve). The inner side of the cutout portion 175 of the valve component 176, on the valve disc 59, becomes a throttling orifice 177 (third pressure-reducing flow path) that connects the passage within the outer passage recess 96 to the second chamber 20 when the valve component 176 abuts against the outer valve seat portion 76. In other words, the throttling orifice 177 ensures that the passage within the outer passage recess 96 and the second chamber 20 are always connected. The throttling orifice 177 is provided in the valve mechanism 178, but it only functions as a throttling part to reduce pressure by narrowing the flow path between the passage within the outer passage recess 96 and the second chamber 20 when the valve mechanism 178 is closed; it does not function as a throttling part when the valve mechanism 178 is open. Therefore, in the hydraulic circuit, as... Figure 5 As shown, the throttling orifice 177 is connected in parallel with the valve mechanism 178. The flow path cross-sectional area S3 of the throttling orifice 177 is smaller than the flow path cross-sectional area S1 of the throttling orifice 608, but larger than the flow path cross-sectional area S2 of the throttling orifice 173. That is, the flow path cross-sectional area S1 of the throttling orifice 608 > the flow path cross-sectional area S3 of the throttling orifice 177 > the flow path cross-sectional area S2 of the throttling orifice 173.

[0117] Between the first chamber 19 and the second chamber 20, oil L is transported via... Figure 2 The piston passage 39, the throttle orifice 608, the rod side chamber 105, the passage in the passage groove 90, the passage in the outer passage recess 96, the passage between the throttle orifice 177 or the valve component 176 for opening the valve and the outer valve seat 76 are shown.

[0118] The piston passage 39, the throttle orifice 608, the rod-side chamber 105, the passage within the passage groove 90, the passage within the outer passage recess 96, the throttle orifice 177, or the passage between the valve component 176 and the outer valve seat 76, form part of a flow path 181 (second flow path) that is connected in parallel with the flow path 162 and through which oil L flows from the first chamber 19 to the second chamber 20. In other words, the flow path 181 is a flow path from the first chamber 19 toward the valve mechanism 178 via the throttle orifice 177 or the valve mechanism 178.

[0119] Here, the flow path 181 from the first chamber 19 toward the valve mechanism 178 can also be entirely connected in parallel with the flow path 162. That is, at least a portion of the flow path 181 only needs to be connected in parallel with the flow path 162. The flow path 181 has a rod-side chamber 105, which includes a passage in the passage grooves 29-31 provided on the surface of the rod 21. Therefore, a portion of the flow path 181 is provided on the surface of the rod 21.

[0120] In flow path 181, a throttling orifice 608 is provided on the upstream side as oil L flows from the first chamber 19 to the second chamber 20, and a throttling orifice 177 is provided on the downstream side. If flow path 181 did not have the throttling orifice 177, then the throttling orifice 608 would be the narrowest part with the smallest cross-sectional area. The cross-sectional area of ​​the flow path is smaller than that of the throttling orifice 608, while the throttling orifice 177 always allows the flow of oil L.

[0121] The flow path 162 is configured in parallel with the flow path 162. The flow path 608 is located in the throttling orifice 608 of the piston 18, through which oil L flows from the first chamber 19, and the pressure of the oil L passing through is reduced with a first intensity.

[0122] The throttle orifice 173, located in valve mechanism 172, allows oil L to flow into the first chamber 19, and reduces the pressure of the oil L by a second strength stronger than the first strength. The throttle orifice 173 is arranged in parallel with flow path 162. The throttle orifice 173 branches off from the passage in the outer passage recess 96 of flow path 181. The cross-sectional area S2 of the flow path of throttle orifice 173 is smaller than the cross-sectional area S1 of the flow path of throttle orifice 608. The throttle orifice 173 communicates with the pressure chamber 151 between pilot valve 53, pilot housing 56, and free valve 111 via the passage in the inner passage recess 95 and the passage in the inner through hole 88. Therefore, the first chamber 19 communicates with the pressure chamber 151 via piston passage 39, throttle orifice 608, rod side chamber 105, passage in passage groove 90, passage in outer passage recess 96, throttle orifice 173, passage in inner passage recess 95, and passage in inner through hole 88. The throttling orifice 173, the passage in the inner passage recess 95, and the passage in the inner through hole 88 constitute a connecting passage 182 that branches off from the flow path 181 and connects to the pressure chamber 151.

[0123] A free valve 111 is disposed in a pressure chamber 151 through which oil L is introduced from the first chamber 19 via a flow path 181 and a connecting path 182, and deforms according to the internal pressure of the pressure chamber 151. The free valve 111 and the recess 82 of the pilot housing 56 that allows its deformation constitute a frequency sensing mechanism 185 (an example of the volume change mechanism in the claims) that can change the damping force by sensing the frequency of the reciprocating movement of the piston 18 (hereinafter referred to as the piston frequency) by changing the volume of the pressure chamber 151. In other words, the free valve 111 of the frequency sensing mechanism 185 is disposed in the pressure chamber 151 and deforms according to the internal pressure of the pressure chamber 151, causing the volume of the pressure chamber 151 to change.

[0124] Pressure chamber 151 applies internal pressure to valve component 161 in the direction of piston 18, even when valve disc 52 of valve component 161 is seated on valve seat portion 47 in the valve-closing direction. Valve component 161 opens by adjusting the pressure of pressure chamber 151. That is, valve mechanism 41, including valve component 161, opens by adjusting the pressure of pressure chamber 151. Pressure chamber 151 is located downstream of throttling orifice 173 when oil L flows from first chamber 19 to second chamber 20, and can apply pressure to valve component 161 in the valve-closing direction generated by oil L.

[0125] In the throttling orifice 177, oil L flows in from the first chamber 19, and the pressure of the oil L passing through is reduced. The throttling orifice 177 is arranged in parallel with the flow path 162. The throttling orifice 177 is arranged in parallel with the throttling orifice 173. The flow path cross-sectional area S3 of the throttling orifice 177 is smaller than the flow path cross-sectional area S1 of the throttling orifice 608, but larger than the flow path cross-sectional area S2 of the throttling orifice 173.

[0126] The valve mechanism 178 is located downstream of the throttle orifice 608 when oil L flows from the first chamber 19 into the valve mechanism 178, such as... Figure 5 As shown, it is arranged in parallel with respect to the throttle orifice 177 in the hydraulic circuit. When oil L flows from the first chamber 19 into the valve mechanism 178, it can allow oil L to flow to the second chamber 20, which becomes the downstream side.

[0127] The valve mechanism 41 is arranged in parallel with the throttling orifice 608. The throttling orifice 173 is located downstream of the throttling orifice 608 and is arranged in series with the throttling orifice 608.

[0128] The pilot housing 56, the pilot valve 53, and the free valve 111 constitute the valve opening control mechanism 186. The valve opening control mechanism 186 has a pressure chamber 151, which applies back pressure to the valve component 161, including the valve disc 141 containing the pilot valve 53, to control its valve opening.

[0129] The outer diameter of the disc 61 is smaller than that of the valve component 176, and is approximately equal to the outer diameter of the inner seat 74 of the pilot housing 56.

[0130] The outer diameter of disk 62 is larger than that of disk 58.

[0131] The outer diameter of the annular component 63 is larger than that of the disk 62 but smaller than that of the valve component 176. The rigidity of the annular component 63 is higher than that of the valve component 176. When the valve component 176 deforms in the opening direction, the disk 62 and the annular component 63 abut against the valve component 176, suppressing the deformation of the valve component 176 in the opening direction by a predetermined amount.

[0132] A check valve 155, consisting of the support portion 146 of the pilot valve 53, the free valve 111, and the bottom 71 of the pilot housing 56, is provided between the pressure chamber 151, the variable chamber 152, and the passage within the outer through hole 87. This restricts the flow of oil L from the pressure chamber 151 through the variable chamber 152 and the passage within the outer through hole 87 to the second chamber 20. On the other hand, it allows the flow of oil L from the second chamber 20 through the passage within the outer through hole 87 and the variable chamber 152 to the pressure chamber 151.

[0133] When the pressure in pressure chamber 151 reaches a specified pressure, valve component 171 moves away from intermediate valve seat portion 75. As described above, valve component 171 and intermediate valve seat portion 75 together constitute valve mechanism 172, which opens the valve and generates damping force when the pressure in pressure chamber 151 reaches the specified pressure. Valve mechanism 172 is provided in the portion of flow path 181 that is connected in parallel with flow path 162. Valve mechanism 172 is provided outside pilot housing 56, and its valve component 171 is disposed opposite to bottom 71. At bottom 71 of pilot housing 56, an inner through hole 88 is provided opposite to valve component 171 of valve mechanism 172.

[0134] As described above, valve component 176 and outer valve seat portion 76 together constitute valve mechanism 178. Valve mechanism 178 is disposed in the portion of flow path 181 that is connected in parallel with flow path 162. Valve mechanism 178 is disposed outside pilot housing 56, with its valve component 176 disposed opposite to bottom 71. At bottom 71 of pilot housing 56, an outer through hole 87 is provided radially outward from valve mechanism 178. When valve component 176 opens by moving away from outer valve seat portion 76, oil L in first chamber 19 flows through flow path 181 to second chamber 20. When valve component 176 closes by sitting on outer valve seat portion 76, it cuts off communication between flow path 181 and second chamber 20. The pilot housing 56 has an intermediate valve seat portion 75 of the valve mechanism 172, which is disposed between the outer valve seat portion 76 and the valve component 176, and has a throttle orifice 173 that further restricts the communication of oil L compared to the throttle orifice 177.

[0135] The valve mechanism 42 on the contraction side, starting from the axial piston 18 side, sequentially includes a disc 201, a disc 202, multiple discs 203, multiple discs 204, a disc 205, a disc 206, and an annular component 207. Discs 201-206 and the annular component 207 are all made of metal and are formed into a perforated circular plate of a certain thickness that can be fitted into the mounting shaft portion 28 of the rod 21 on its inner side.

[0136] Disks 203 and 204 constitute a valve component 212 that can sit on or leave the valve seat portion 49. The valve component 212, by leaving the valve seat portion 49, connects the piston passage 40 to the first chamber 19 and inhibits the flow of oil L between them, generating a damping force. A flow path 210 is formed between the piston passage 40, the valve component 212, and the valve seat portion 49. The inner side of the cutout portion 211 of the disk 202 becomes a throttling orifice 213 that connects the first chamber 19 and the second chamber 20 via the flow path 210 even when the disk 202 is in contact with the valve seat portion 49. In other words, the piston passage 40, the throttling orifice 213, and the separated valve component 212 and valve seat portion 49 form a flow path 210 through which oil L, a fluid, flows from one of the first chamber 19 and the second chamber 20, namely the second chamber 20.

[0137] The flow path 210 serves as a constriction-side flow path for the oil L, which flows from the second chamber 20 to the first chamber 19 during the movement of the piston 18 toward the second chamber 20, i.e., the contraction stroke. A valve mechanism 42, consisting of a valve seat 49 and a valve component 212, is provided in the flow path 210. By opening and closing the flow path 210 using the valve component 212, the flow of oil L is suppressed, thereby generating a damping force. In other words, the valve component 212, provided in the flow path 210, suppresses the flow of oil L caused by the sliding of the piston 18 toward the contraction side, thereby generating a damping force.

[0138] The disc 206 and the annular component 207 suppress the deformation of the valve component 212 in the opening direction as specified.

[0139] The valve opening control mechanism 186, consisting of a pilot housing 56, a pilot valve 53, and a free valve 111, includes a check valve 155 and a frequency sensing mechanism 185. The free valve 111 of the valve opening control mechanism 186 deforms according to the frequency of the reciprocating movement of the piston 18, thereby changing the capacity of the pressure chamber 151, which is always in communication with the first chamber 19, and the capacity of the variable chamber 152, which is always in communication with the second chamber 20.

[0140] On rod 21, mounting shaft portion 28 is fitted with its respective inner side. At the end of main shaft portion 27 on the mounting shaft portion 28 side, annular component 207, disc 206, disc 205, multiple discs 204, multiple discs 203, disc 202, disc 201, piston 18, disc 51, valve disc 52, pilot valve 53, pilot housing 56, multiple valve discs 57, disc 58, valve disc 59, multiple valve discs 60, disc 61, disc 62, and annular component 63 are sequentially overlapped. At this time, pilot housing 56 fits the sealing portion 145 of pilot valve 53 with the outer cylindrical portion 72. Additionally, at this time, free valve 111 is arranged between the bottom 71 of pilot housing 56 and the support portion 146 of pilot valve 53.

[0141] With the parts configured in this way, the retainer 221 engages with the male thread 32 of the mounting shaft portion 28, which protrudes from the annular member 63. Thus, the inner circumference or all of the parts that overlap as described above from the annular member 207 to the annular member 63 are clamped axially by the end of the mounting shaft portion 28 of the main shaft portion 27 of the rod 21 and the retainer 221. At this time, the valve disc 141 of the pilot valve 53, opposite to the piston 18, abuts against the inner cylindrical portion 73 of the pilot housing 56. Furthermore, at this time, the free valve 111 is clamped by the support portion 146 of the pilot valve 53 and the pilot housing 56, and is not axially tightened.

[0142] The piston 18, discs 51, 58, 61, 62, 201, 202, 203, 204, 205, 206, valve discs 52, 57, 59, 60, pilot valve 53, pilot housing 56, annular components 63, 207, and free valve 111, and the rod 21, along with the parts on which they are mounted, constitute the valve structure 225. Therefore, the buffer device 1 has the valve structure 225.

[0143] Valve structure 225 has a flow path 162 that connects upstream of a first chamber 19 to a second chamber 20 that becomes the downstream side. Valve structure 225 has a valve mechanism 41 disposed in the flow path 162, having a valve seat portion 47 and a valve component 161 seated on or away from the valve seat portion 47. Valve structure 225 has a pressure chamber 151 capable of applying pressure generated by oil L in the valve closing direction to the valve component 161. Valve structure 225 has a flow path 181, at least a portion of which is disposed parallel to the flow path 162 and connects upstream of the first chamber 19 to the second chamber 20 that becomes the downstream side. Valve structure 225 has a valve mechanism 178 disposed in the flow path 181, consisting of an outer valve seat portion 76 and a valve component 176 seated on or away from the outer valve seat portion 76. The valve structure 225 has a communication passage 182 that connects the inner side of the outer valve seat portion 76, which is the upstream side, to the pressure chamber 151, which is the downstream side.

[0144] The hydraulic circuit diagram of valve structure 225 is as follows: Figure 5 As shown. Figure 5 As shown, in valve structure 225, a flow path 162 is provided connecting the first chamber 19 and the second chamber 20. A valve mechanism 41 is provided in flow path 162. Additionally, in valve structure 225, a flow path 181 is provided connecting the first chamber 19 and the second chamber 20. In flow path 181, starting from the first chamber 19 side, a throttling orifice 608, a valve mechanism 178, and a throttling orifice 177 are sequentially provided. The valve mechanism 178 and the throttling orifice 177 are arranged in parallel. Furthermore, in valve structure 225, a valve mechanism 172 and a throttling orifice 173 are branched off from the throttling orifice 608 and the valve mechanism 178 and the throttling orifice 177 of flow path 181 and arranged in parallel. The valve mechanism 172 and the throttling orifice 173 are connected to the valve opening control mechanism 186 via a connecting path 182. Figure 6 The pressure chamber 151 shown is connected. The pressure in the pressure chamber 151 acts on... Figure 5 The valve component 161 of the valve mechanism 41 shown. (As shown...) Figure 6 As shown, pressure chamber 151 is separated from variable chamber 152 by free valve 111, forming frequency sensing mechanism 185. Variable chamber 152 and... Figure 5 The second chamber 20 shown is connected. In the valve control mechanism 186, the second chamber 20 and... Figure 6 A check valve 155 is installed between the pressure chambers 151 shown. It should be noted that... Figure 6 In the diagram, for ease of illustration based on a hydraulic circuit, the valve core of the check valve 155 is provided separately from the free valve 111 of the frequency sensing mechanism 185, but the free valve 111 also serves as the valve core of the check valve 155. Of course, the free valve 111 of the frequency sensing mechanism 185 can also be configured as follows: Figure 6 The valve cores of the check valve 155 are arranged separately as shown. Figure 5 As shown, in valve structure 225, a flow path 210 is provided to connect the second chamber 20 and the first chamber 19. A valve mechanism 42 and a throttling orifice 213 are arranged in parallel in the flow path 210.

[0145] like Figure 5 As shown in the hydraulic circuit diagram, the buffer device 1 has a flow path 162 connecting the first chamber 19 to the second chamber 20, a valve (i.e., valve mechanism 41) disposed in the flow path 162, and a throttling orifice 608 that allows oil L to flow into the first chamber 19 and reduces the pressure of the oil L with a first intensity. Additionally, the buffer device 1 has a throttling orifice 173 and a throttling orifice 177. The throttling orifice 173 is disposed in parallel with the flow path 162 and has a smaller cross-sectional area than the throttling orifice 608. The throttling orifice 177 is disposed in parallel downstream of the throttling orifice 608, has a smaller cross-sectional area than the throttling orifice 608, and a larger cross-sectional area than the throttling orifice 173. Furthermore, the buffer device 1 has... Figure 6The pressure chamber 151 and frequency sensing mechanism 185 are shown. The pressure chamber 151 is located downstream of the throttle orifice 173 and can apply pressure in the valve mechanism 41 in the valve-closing direction generated by the oil L. The frequency sensing mechanism 185 is disposed in the pressure chamber 151 and deforms according to the internal pressure of the pressure chamber 151, causing the volume of the pressure chamber 151 to change. Additionally, as shown... Figure 5 As shown, the buffer device 1 has a valve mechanism 178, which is located downstream of the throttle orifice 608 and is arranged in parallel with the throttle orifice 177, enabling the incoming oil L to flow into the second chamber 20, which becomes the downstream chamber.

[0146] In addition, the valve mechanism 41 of the buffer device 1 is arranged in parallel with the throttle orifice 608, and the throttle orifice 173 is located downstream of the throttle orifice 608 and is arranged in series with the throttle orifice 608.

[0147] 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 component 231 that separates the second chamber 20 and the oil storage chamber 6, a disc valve 232 provided on the lower side of the base component 231, i.e., the side of the oil storage chamber 6, a disc valve 233 provided on the upper side of the base component 231, i.e., the side of the second chamber 20, and a mounting pin 234 for mounting the disc valve 232 and the disc valve 233 on the base component 231.

[0148] Disc valve 232 utilizes base component 231 to form a damping valve mechanism 237 on the contraction side. The damping valve mechanism 237 opens during the contraction stroke of the buffer device 1, allowing oil L to flow from the second chamber 20 to the oil storage chamber 6 and generating a damping force. Disc valve 233 utilizes base component 231 to form a suction valve mechanism 238. The suction valve mechanism 238 opens during the extension stroke of the buffer device 1, allowing oil L to flow from the oil storage chamber 6 to the second chamber 20. It should be noted that the suction valve mechanism 238 primarily functions to allow liquid that does not actually generate damping force to flow from the oil storage chamber 6 to the second chamber 20, supplementing the insufficient liquid due to the extension of rod 21 from the cylinder 2.

[0149] Next, refer to Figure 7 The characteristic curve of damping force versus piston speed shown illustrates the operation of valve structure 225. Figure 7 In the diagram, solid lines Y1, Y2, and Y3 represent the characteristic curves of valve structure 225.

[0150] During the extension stroke of rod 21 moving to the extension side, when the moving speed of piston 18 (hereinafter referred to as piston speed) is a slightly low speed range X1 that is slower than the first specified speed, and the piston frequency is a low frequency input that is lower than the specified frequency, the oil L from the first chamber 19 flows to the pressure chamber 151 through the flow path 181 having a piston passage 39, a throttle orifice 608, a rod side chamber 105, a passage in the passage groove 90, and a passage in the outer passage recess 96, and through the connecting passage 182 having a throttle orifice 173, a passage in the inner passage recess 95, and a passage in the inner through hole 88.

[0151] During the extension stroke of this low-frequency input in the micro-low speed range X1, the amplitude of piston 18 is large. Therefore, the amount of oil L flowing into pressure chamber 151 is large, and the deformation of free valve 111 is large. Thus, in the initial stage of the extension stroke, the deformed free valve 111 immediately abuts against the recess 82, limiting its further deformation, and oil L does not flow from the first chamber 19 to pressure chamber 151. It should be noted that at this time, variable chamber 152 discharges oil L to the second chamber 20 through the passage in the outer through hole 87. During the extension stroke of this low-frequency input in the micro-low speed range X1, as described above, when free valve 111 abuts against the recess 82, limiting its further deformation, the volume of pressure chamber 151 does not increase. Therefore, the pressure in pressure chamber 151 rises, limiting the opening of valve component 161 of valve mechanism 41. That is, valve component 161 of valve mechanism 41 is not open.

[0152] Therefore, during the extension stroke at low-frequency input in the micro-low speed range X1, the oil L from the first chamber 19 flows into the second chamber 20 through the flow path 181, which has a piston passage 39, a throttle orifice 608, a rod-side chamber 105, a passage in the passage groove 90, a passage in the outer passage recess 96, and a throttle orifice 177, from its end of the throttle orifice 177. At this time, the oil L from the first chamber 19 is throttled by the throttle orifice 608, and then further throttled by the throttle orifice 177, which has a flow path cross-sectional area smaller than the throttle orifice 608, and flows into the second chamber 20. In addition, the oil L from the first chamber 19 also flows into the second chamber 20 through the flow path 210, which includes the throttle orifice 213. Therefore, as Figure 7 As shown by the solid line Y1, at low-frequency input in the micro-low speed domain X1, a damping force with orifice characteristics (damping force approximately proportional to the square of the piston speed) is generated. Therefore, during the extension stroke at low-frequency input in the micro-low speed domain X1, the rate of increase of the damping force relative to the piston speed is higher than the rate of increase of the piston speed.

[0153] During the extension stroke, when the piston speed is in the low-speed range X1, which is slower than the first specified speed, and the piston frequency is a high-frequency input above the specified frequency, the oil L from the first chamber 19 flows into the pressure chamber 151 via the flow path 181 containing the throttle orifice 608 and the connecting path 182 containing the throttle orifice 173, which branches off from the middle of the flow path 181.

[0154] During the extension stroke at high-frequency input in this low-speed range X1, the amplitude of piston 18 is small. Therefore, the amount of oil L flowing into pressure chamber 151 is small, and the deformation of free valve 111 is small. Therefore, when oil L from first chamber 19 is introduced into pressure chamber 151 from flow path 181 via connecting path 182, according to this situation, free valve 111, which was previously formed into a flat plate and abutted against seat 80, elastically deforms into recess 82 in a state of blocking the communication between pressure chamber 151 and variable chamber 152, thereby increasing the volume of pressure chamber 151, while simultaneously discharging oil L from variable chamber 152 through passage in outer through hole 87 to second chamber 20.

[0155] While the free valve 111 is deformed, oil L is introduced from the first chamber 19 into the pressure chamber 151. However, the amount of oil L introduced from the first chamber 19 into the pressure chamber 151 is small. Therefore, the deformation of the free valve 111 is small, and it does not become abutted against the recess 82 and restrict deformation as it would during low-frequency input. In this way, by flexing the free valve 111, the pressure rise in the pressure chamber 151 is suppressed, and the valve component 161 can be opened easily.

[0156] Therefore, during the extension stroke at high-frequency input in the low-speed range X1, the oil L from the first chamber 19 flows not only through the flow path 181 containing the throttle orifice 608, through its end throttle orifice 177, to the second chamber 20, but also through the flow path 162 simultaneously with opening the valve mechanism 41, that is, simultaneously with causing the valve component 161 to leave the valve seat portion 47, to flow into the second chamber 20. Therefore, as... Figure 7 As shown by the solid line Y2, during the extension stroke at high-frequency input in the low-speed domain X1, a damping force with valve characteristics (damping force approximately proportional to piston speed) is generated. During the extension stroke at high-frequency input in the low-speed domain X1, the damping force is greater than... Figure 7 The solid line Y1 indicates a decrease in the extension stroke of X1 at low-frequency input in the micro-low-speed domain. That is, in the extension stroke of X1 at high-frequency input, the damping force characteristics become gentler than those in the low-frequency input extension stroke of X1 in the micro-low-speed domain. Furthermore, in the extension stroke of X1 at high-frequency input, the rate of increase of the damping force relative to piston speed is lower than that in the low-frequency input extension stroke of X1 in the micro-low-speed domain.

[0157] During the extension stroke, when the piston speed is above the first specified speed and below the second specified speed which is slower than the first specified speed in the low-speed range X2, and the piston frequency is below the specified frequency in the low-frequency input, the oil L from the first chamber 19 flows from the flow path 181 containing the throttle orifice 608 through the connecting path 182 containing the throttle orifice 173 to the pressure chamber 151, just as in the low-frequency input of the micro low-speed range X1.

[0158] During the extension stroke of this low-frequency input in the low-speed range X2, similar to the low-frequency input in the micro-low-speed range X1, the amplitude of piston 18 is large. Therefore, the amount of oil L flowing into pressure chamber 151 is large, and the deformation of free valve 111 is large. Thus, in the initial stage of the extension stroke, the deformed free valve 111 immediately abuts against the recess 82, limiting its further deformation, and the volume of pressure chamber 151 does not increase. During the extension stroke of this low-frequency input in the low-speed range X2, the volume of pressure chamber 151 does not increase; therefore, the pressure in pressure chamber 151 rises, inhibiting the opening of valve component 161 of valve mechanism 41. That is, during the extension stroke of the low-frequency input in the low-speed range X2, valve component 161 of valve mechanism 41 also does not open.

[0159] During the extension stroke at low-frequency input in the low-speed range X2, the flow rate of oil L flowing from the first chamber 19 to the flow path 181 is greater than that during the extension stroke at low-frequency input in the micro-low-speed range X1. Therefore, oil L flows from the first chamber 19 into the flow path 181, simultaneously opening the valve mechanism 178 and moving the valve component 176 away from the outer valve seat 76, towards the second chamber 20. This generates a damping force characteristic of the valve. Therefore, as... Figure 7 As shown by the solid line Y1, during the extension stroke at low frequency input in the low-speed domain X2, in terms of the characteristics of damping force relative to piston speed, the rate of increase of damping force relative to piston speed is lower than that during the extension stroke at low frequency input in the micro-low-speed domain X1.

[0160] During the extension stroke, in the low-speed range X2 where the piston speed is above the first specified speed and slower than the second specified speed, and at the high-frequency input where the piston frequency is above the specified frequency, the oil L from the first chamber 19 flows into the pressure chamber 151 via the flow path 181 containing the throttle orifice 608 and the connecting path 182 containing the throttle orifice 173, just as it does during the high-frequency input in the low-speed range X1.

[0161] During the extension stroke at high frequency input in this low-speed range X2, similar to the high-frequency input in the micro-low-speed range X1, the amplitude of piston 18 is small. Therefore, the amount of oil L flowing into pressure chamber 151 is small, and the deformation of free valve 111 is minimal. Thus, by flexing free valve 111, the pressure rise in pressure chamber 151 can be suppressed, and valve component 161 can be easily opened.

[0162] Therefore, during the extension stroke at high-frequency input in the low-speed domain X2, the oil L from the first chamber 19 flows into the second chamber 20 in flow path 181, simultaneously opening the valve mechanism 178 and causing the valve component 176 to leave the outer valve seat 76. At the same time, the oil L from the first chamber 19 flows into the second chamber 20 in flow path 162, simultaneously opening the valve mechanism 41 and causing the valve component 161 to leave the valve seat 47. Therefore, as... Figure 7 As shown by the solid line Y2, during the extension stroke at high-frequency input in the low-speed domain X2, the damping force decreases compared to the low-frequency input in the low-speed domain X2. Furthermore, during the extension stroke at high-frequency input in the low-speed domain X2, the rate of increase of the damping force relative to piston speed is lower than that during the low-frequency input in the low-speed domain X2. However, during the extension stroke at high-frequency input in the low-speed domain X2, the rate of increase of the damping force relative to piston speed is the same as that during the extension stroke at high-frequency input in the micro-low-speed domain X1.

[0163] During the extension stroke, when the piston speed is in the medium-high speed range X3 above the second specified speed and the piston frequency is below the specified frequency low-frequency input, the extension stroke is the same as that during the low-frequency input in the low speed range X2. The oil L from the first chamber 19 flows to the pressure chamber 151 through the flow path 181 containing the throttle orifice 608 and through the connecting path 182 containing the throttle orifice 173.

[0164] During the extension stroke of the low-frequency input in the medium-high speed domain X3, similar to the low-frequency input in the low-speed domain X2, the amplitude of piston 18 is large. Therefore, the amount of oil L flowing into pressure chamber 151 is large, and the deformation of free valve 111 is large. Thus, in the initial stage of the extension stroke, the deformed free valve 111 immediately abuts against the recess 82, limiting its further deformation, and the volume of pressure chamber 151 does not increase. During the extension stroke of the low-frequency input in the medium-high speed domain X3, the volume of pressure chamber 151 does not increase. Therefore, although the pressure in pressure chamber 151 rises, in terms of the force (hydraulic pressure) acting on valve component 161, the force applied in the opening direction from the piston passage 39, which is directly connected to the first chamber 19, is greater than the force applied in the closing direction from pressure chamber 151. Therefore, during the low-frequency input in the medium-high speed domain X3, valve mechanism 41 opens. That is, valve component 161 moves away from the valve seat portion 47 of piston 18 and opens. As a result, in addition to the flow through the flow path 181 that opens the valve mechanism 178 to the second chamber 20, more oil L flows into the second chamber 20 via the flow path 162, which includes the passage between the valve component 161 and the valve seat portion 47, thus further suppressing the rise in damping force. Therefore, as Figure 7As shown by the solid line Y1, in the extension stroke of the low-frequency input in the mid-to-high speed domain X3, in terms of the characteristics of the damping force relative to the piston speed, the rate of increase of the damping force relative to the piston speed is lower than that of the extension stroke at the low-frequency input in the low speed domain X2.

[0165] During the extension stroke, when the piston speed is in the medium-high speed range X3 above the second specified speed and the piston frequency is above the specified frequency, the oil L from the first chamber 19 flows in the flow path 181 containing the throttle orifice 608 in the same way as when the low speed range X2 is input at high frequency, and flows to the pressure chamber 151 via the connecting path 182 containing the throttle orifice 173.

[0166] During the extension stroke at high frequency input in the medium-high speed domain X3, the amplitude of piston 18 is small, similar to that at high frequency input in the low speed domain X2. Therefore, the amount of oil L flowing into pressure chamber 151 is small, and the deformation of free valve 111 is minimal. Thus, by flexing free valve 111, the pressure rise in pressure chamber 151 can be suppressed, and valve component 161 can be easily opened.

[0167] Therefore, during the extension stroke at high-frequency input in the medium-high speed domain X3, the oil L from the first chamber 19 flows into the second chamber 20 through flow path 181, simultaneously opening the valve mechanism 178 and separating the valve component 176 from the outer valve seat 76. At the same time, the oil L from the first chamber 19 flows into the second chamber 20 through flow path 162, simultaneously opening the valve mechanism 41 and separating the valve component 161 from the valve seat 47. Therefore, as... Figure 7 As shown by the solid line Y2, during the extension stroke at high-frequency input in the mid-to-high speed domain X3, the damping force decreases compared to the low-frequency input in the mid-to-high speed domain X3. Furthermore, during the extension stroke at high-frequency input in the mid-to-high speed domain X3, the rate of increase of the damping force relative to piston speed is the same as during the extension stroke at high-frequency input in the low-speed domain X2, in terms of the characteristics of the damping force relative to piston speed.

[0168] During the contraction stroke of rod 21 moving towards the contraction side, in the micro-low speed range X4 where the piston speed is slower than the fourth predetermined speed, oil L from the second chamber 20 flows into the first chamber 19 via the piston passage 40 on the contraction side and the throttle orifice 213 of the valve component 212 of the valve mechanism 42. Simultaneously, oil L from the second chamber 20 flows into the flow path 181 from the throttle orifice 177, and then flows into the first chamber 19 via the flow path 181 containing the throttle orifice 608. At the same time, oil L from the second chamber 20 flows through the passage within the outer through-hole 87 and the variable chamber 152, simultaneously opening the check valve 155, from the pressure chamber 151 and the connecting passage 182 through the throttle orifice 173, and then through the flow path 181 containing the throttle orifice 608 into the first chamber 19. Therefore, during the contraction stroke in the micro-low speed range X4, a damping force characteristic of the throttle orifice is generated. Therefore, as... Figure 7 As shown by the solid line Y3, during the contraction stroke in the low-speed range X4, the rate of increase of the damping force is higher than that of the piston speed in terms of the characteristics of the damping force relative to the piston speed.

[0169] During the contraction stroke of the low-speed range X5, where the piston speed is above the fourth specified speed but slower than the fifth specified speed (which is higher than the fourth specified speed), the oil L flowing from the second chamber 20 through the passage in the outer through-hole 87 and the variable chamber 152, while opening the check valve 155, flows through the pressure chamber 151 and the connecting passage 182. Simultaneously, this opens the valve mechanism 172 at the end of the connecting passage 182, that is, while causing the valve component 171 to leave the intermediate valve seat 75, and flows through the flow path 181 containing the throttle orifice 608 to the first chamber 19. Therefore, during the contraction stroke of the low-speed range X5, a damping force characteristic of the valve is generated. Therefore, as... Figure 7 As shown by the solid line Y3, in the contraction stroke of the low-speed domain X5, in terms of the characteristics of the damping force relative to the piston speed, the rate of increase of the damping force relative to the piston speed is lower than that in the contraction stroke of the micro-low-speed domain X4.

[0170] During the contraction stroke of the piston in the medium-high speed range X6, where the piston speed is above the fifth specified speed, similar to the contraction stroke in the low-speed range X5, oil L flows from the second chamber 20 to the first chamber 19 via the flow path 181 containing the throttle orifice 608 while simultaneously opening the valve mechanism 172. During the contraction stroke of the medium-high speed range X6, simultaneously, oil L is introduced from the second chamber 20 into the piston passage 40 on the contraction side, and flows into the first chamber 19 while simultaneously opening the valve mechanism 42, that is, while causing the valve component 212 to leave the valve seat portion 49. Therefore, as... Figure 7 As shown by the solid line Y3, in the contraction stroke of the medium-high speed domain X6, in terms of the characteristics of the damping force relative to the piston speed, the rate of increase of the damping force relative to the piston speed is lower than that in the contraction stroke of the low speed domain X5.

[0171] Patent Document 1 disclosed above discloses a buffer device whose damping force can be changed by sensing frequency. In this buffer device, it is required to mitigate changes in attenuation characteristics.

[0172] The buffer device 1 of the first embodiment has a flow path 162 connecting a first chamber 19 inside the cylinder 2 to a second chamber 20, and a valve mechanism 41 disposed in the flow path 162. Furthermore, the buffer device 1 has a throttling orifice 608 from which oil L flows in from the first chamber 19 and reduces the pressure of the oil L with a first intensity; a throttling orifice 173 disposed in parallel with the flow path 162 and having a smaller cross-sectional area than the throttling orifice 608; and a throttling orifice 177 disposed in parallel with the throttling orifice 173 and having a smaller cross-sectional area than the throttling orifice 608 and a larger cross-sectional area than the throttling orifice 173. Additionally, the buffer device 1 has a pressure chamber 151 located downstream of the throttling orifice 173 and capable of applying a pressure generated by the oil L in the valve-closing direction to the valve mechanism 41; and a frequency sensing mechanism 185 disposed in the pressure chamber 151 that deforms according to the internal pressure of the pressure chamber 151 and causes a change in the volume of the pressure chamber 151. In addition, the buffer device 1 has a valve mechanism 178, which is arranged in parallel with the throttle orifice 177, so that the incoming oil L can flow into the second chamber 20 downstream.

[0173] The buffer device 1 includes a valve mechanism 41, a valve mechanism 178, and a throttling orifice 177, thus enabling it to mitigate changes in damping characteristics. The buffer device 1 also includes a throttling orifice 608 and a throttling orifice 173, allowing for detailed adjustment of the damping force characteristics and further mitigating changes in damping characteristics. That is, in the buffer device disclosed in Patent Document 1, as... Figure 7 As shown by the dashed lines Z1 and Z2, the damping force characteristics at low-frequency input, especially represented by dashed line Z1, exhibit a large variation. Figure 7 As shown by the solid line Y1, the buffer device 1 can smoothly change the damping force characteristics.

[0174] In the buffer device 1, the valve mechanism 41 is connected in parallel with the throttling orifice 608, and the throttling orifice 173 is located downstream of the throttling orifice 608 and connected in series with it. Therefore, the buffer device 1 can adjust the damping force characteristics in more detail and can further mitigate changes in the attenuation characteristics.

[0175] The valve structure 225 of the buffer device 1 has a flow path 162 that connects upstream of the first chamber 19 to a second chamber 20 that is downstream, and a valve member 161 disposed in the flow path 162 and having a valve seat 47 and a valve member 161 seated on or away from the valve seat 47. Furthermore, the valve structure 225 has a pressure chamber 151 capable of applying pressure generated by the oil L in the valve-closing direction to the valve member 161, and a flow path 181 at least partially disposed parallel to the flow path 162 and connected upstream of the first chamber 19 to the second chamber 20 that is downstream. Additionally, the valve structure 225 has a valve mechanism 178 disposed in the flow path 181 and consisting of an outer valve seat 76 and a valve member 176 seated on or away from the outer valve seat 76, and a communication path 182 connecting the inner side of the upstream outer valve seat 76 to the downstream pressure chamber 151. Therefore, the buffer device 1 can mitigate changes in damping characteristics.

[0176] A portion of the flow path 181 of the buffer device 1 is provided on the surface or inside of the rod 21. The pressure chamber 151 is formed by a bottomed cylindrical pilot housing 56 having a bottom 71 and an outer cylindrical portion 72. The outer valve seat portion 76 is provided on the side of the bottom 71 facing the second chamber 20. Therefore, the buffer device 1 can be compacted.

[0177] The valve mechanism 178 of the buffer device 1 also has a throttling orifice 177, the cross-sectional area of ​​which is smaller than that of the throttling orifice 608, which is the narrowest part of the flow path 181, allowing the oil L to remain connected at all times. Therefore, the buffer device 1 can further mitigate changes in the damping characteristics.

[0178] The pilot housing 56 of the buffer device 1 also has a valve mechanism 172, which is disposed between the outer valve seat portion 76 and the valve component 176, further restricting the flow of oil L compared to the throttle orifice 177. Therefore, the buffer device 1 can further mitigate changes in damping characteristics.

[0179] The bottom 71 of the pilot housing 56 of the buffer device 1 has an outer through hole 87 on the side of the bottom 71 facing the second chamber 20, which is radially outward from the outer valve seat portion 76. The buffer device 1 has a free valve 111 on the pilot housing 56. The free valve 111 blocks the outer through hole 87 from the inside of the pressure chamber 151, and the volume of the pressure chamber 151 can be changed by the pressure of the oil L in the pressure chamber 151. Therefore, the buffer device 1 can be compacted.

[0180] [Second Implementation]

[0181] Next, mainly based on Figures 8-10The second embodiment will be described focusing on the parts that differ from the first embodiment. It should be noted that the same parts as in the first embodiment are denoted by the same names and the same reference numerals.

[0182] like Figure 8 As shown, in the buffer device 1A of the second embodiment, a valve structure 225A that is partially different from the valve structure 225 of the first embodiment is used instead of the valve structure 225.

[0183] Valve structure 225A has a valve mechanism 178A that is partially different from valve mechanism 178, replacing valve mechanism 178. Valve mechanism 178A has a valve component 176A that is partially different from valve component 176, replacing valve component 176. Valve component 176A has a valve disc 59A that is partially different from valve disc 59, replacing valve disc 59. Valve disc 59A has a throttling orifice 177A with a flow path cross-sectional area smaller than that of the throttling orifice 177 of valve disc 59. It should be noted that valve mechanism 178A can also be configured as a structure without a throttling orifice 177A.

[0184] Valve structure 225A has a rod 21A that is partially different from rod 21 instead of rod 21. Rod 21A has a mounting shaft portion 28A that is partially different from mounting shaft portion 28 instead of mounting shaft portion 28. In addition to the passage grooves 29 to 31 of the first embodiment, the mounting shaft portion 28A also has passage grooves 251 and passage grooves 252 formed on its outer periphery.

[0185] The passage groove 251 is formed around the entire circumference of the mounting shaft portion 28A and is annular. The passage groove 251 is located on the opposite side of the main shaft portion 27 in the axial direction of the mounting shaft portion 28, which is closer to the main shaft portion 27 than the passage groove 30.

[0186] The passageway 252 extends axially along the mounting shaft portion 28A, connecting the passageway 30 and the passageway 251. The passageway in the passageway 252 connects the passageway in the passageway 30 and the passageway in the passageway 251.

[0187] It should be noted that the passageways 29-31, 251, and 252 can also be achieved by making the interior of rod 21B hollow.

[0188] Valve structure 225A has a low-speed damping force generating section 261. For example... Figure 9As shown, on the axial side of the valve component 176A of the valve mechanism 178A, opposite to the pilot housing 56, the disk 262 engages with the mounting shaft portion 28A of the rod 21A radially inward. On the axial side of the disk 262, opposite to the valve component 176A, the low-speed damping force generating part 261 engages with the mounting shaft portion 28A of the rod 21A radially inward. On the axial side of the low-speed damping force generating part 261, opposite to the disk 262, the same disks 61 and 62 and the annular component 63 as in the first embodiment are provided.

[0189] The low-speed damping force generating part 261, along the axial direction of the rod 21, includes, from the side of the disc 262, a disc 271, a spring component 272, a disc 273, a valve disc 274, a valve seat component 276 with an O-ring 275 on its outer periphery, a valve disc 277, a disc 278, a spring component 279, and a cap component 280.

[0190] The cap component 280 is a one-piece molded cylindrical part with a bottom. The cap component 280 has a bottom 301 and a cylindrical portion 302. The bottom 301 is a perforated circular plate. The cap component 280 allows the mounting shaft portion 28A of the rod 21A to fit radially inward from the bottom 301. The cylindrical portion 302 is cylindrical. The cylindrical portion 302 extends from the outer periphery of the bottom 301 towards one axial side of the bottom 301. The cylindrical portion 302 of the cap component 280 extends from the bottom 301 towards the pilot housing 56. The bottom 301 of the cap component 280 abuts against the disk 61.

[0191] The spring member 279 has a base plate portion 311 and a plurality of spring plate portions 312. The base plate portion 311 is a perforated circular plate. The mounting shaft portion 28A is fitted into the inner side of the base plate portion 311 in a radial direction. The plurality of spring plate portions 312 are disposed on the outer periphery of the base plate portion 311. The plurality of spring plate portions 312 are arranged at intervals along the circumference of the base plate portion 311. The plurality of spring plate portions 312 extend radially outward from the base plate portion 311. The spring plate portions 312 are inclined relative to the base plate portion 311, such that the closer to the protruding front end side, the further away from the base plate portion 311 in the axial direction. The base plate portion 311 of the spring member 279 abuts against the bottom 301 of the cap member 280. The spring member 279 is disposed at the bottom 301 such that the spring plate portions 312 are disposed at the bottom 301 in a manner that the spring plate portions 312 are further away from the bottom 301 in the axial direction of the base plate portion 311.

[0192] The disk 278 is a perforated circular plate. The disk 278 abuts against the base plate 311 of the spring component 279.

[0193] The valve disc 277 is a perforated circular disc. The valve disc 277 abuts against the disc 278 and the plurality of spring plate portions 312 of the spring component 279. The valve disc 277 abuts against the valve seat component 276.

[0194] The valve seat component 276 is a perforated circular plate. A through hole 321 extending axially is formed on the valve seat component 276. The through hole 321 is formed at the radial center of the valve seat component 276. The through hole 321 has a hole body portion 322 and an axial groove 323. The axial groove 323 is recessed from the hole body portion 322 towards the radially outer side of the valve seat component 276. The axial groove 323 extends axially along the valve seat component 276. The axial groove 323 is disposed on one side from the axial center of the valve seat component 276. A plurality of axial grooves 323 are formed at equal intervals along the circumference of the valve seat component 276. The valve seat component 276 engages the mounting shaft portion 28A of the rod 21A in its hole body portion 322. The passage in the axial groove 323 of the valve seat component 276 communicates with the passage in the passage groove 251 of the rod 21A.

[0195] The valve seat component 276 has an inner seat portion 331, a valve seat portion 332, an inner seat portion 333, a valve seat portion 334, and a main body portion 335. Both the inner seat portion 331 and the valve seat portion 332 are formed at the axial end of the valve seat component 276 on one side where an axial groove 323 is formed. The inner seat portion 331 is configured to surround the bore main body portion 322 and the axial groove 323. The inner seat portion 331 is annular. The valve seat portion 332 extends radially outward from the inner seat portion 331.

[0196] Both the inner seat portion 333 and the valve seat portion 334 are formed at the ends opposite to the side of the valve seat component 276 that has the axial groove 323 in the axial direction. The inner seat portion 333 is configured to surround the bore body portion 322. The inner seat portion 333 is annular. The valve seat portion 334 extends radially outward from the inner seat portion 333.

[0197] The main body 335 is the axial portion of the valve seat component 276 between the inner seat portion 331 and the valve seat portion 332, and between the inner seat portion 333 and the valve seat portion 334. The main body 335 is a perforated circular plate.

[0198] The inner seat portion 331 protrudes along the axial direction of the main body portion 335 from its inner peripheral edge on the side where the axial groove 323 is formed. The inner seat portion 331 is annular with the central axis of the main body portion 335 as its center. The valve seat portion 332 protrudes from the main body portion 335 to the same side as the inner seat portion 331 along the axial direction of the main body portion 335, on the radially outer side of the inner seat portion 331. The front end face of the inner seat portion 331 on the side opposite to the main body portion 335 is a flat surface. The front end face of the valve seat portion 332 on the side opposite to the main body portion 335 is also a flat surface. The front end faces of the inner seat portion 331 and the valve seat portion 332 extend in a direction orthogonal to the axis of the main body portion 335. The front end faces of the inner seat portion 331 and the valve seat portion 332 are disposed on the same plane.

[0199] The inner seat portion 333 protrudes from the inner peripheral edge of the main body portion 335 opposite to the side where the axial groove 323 is formed, along the axial direction of the main body portion 335 towards the side opposite to the inner seat portion 331. The inner seat portion 333 is annular with the central axis of the main body portion 335 as its center. The valve seat portion 334 protrudes from the main body portion 335 towards the same side as the inner seat portion 333, along the axial direction of the main body portion 335, on the radially outer side of the inner seat portion 333. The front end face of the inner seat portion 333 opposite to the main body portion 335 is a flat surface. The front end face of the valve seat portion 334 opposite to the main body portion 335 is also a flat surface. The front end faces of the inner seat portion 333 and the valve seat portion 334 extend in a direction orthogonal to the axis of the main body portion 335. The front end faces of the inner seat portion 333 and the valve seat portion 334 are disposed on the same plane.

[0200] The valve seat portion 332 has a plurality of valve seat constituent portions 341. These valve seat constituent portions 341 are of the same shape. These valve seat constituent portions 341 are arranged at equal intervals along the circumference of the main body portion 335. These valve seat constituent portions 341 extend radially outward from the inner seat portion 331.

[0201] A passage recess 342 is formed on the inner side of each valve seat component 341. The passage recess 342 is formed by surrounding a portion of the valve seat component 341 and an inner seat portion 331. The passage recess 342 is axially recessed from the front end of the protruding side of the valve seat component 341 toward the main body portion 335. The bottom surface of the passage recess 342 is formed in the main body portion 335. A passage recess 342 is formed on the inner side of all valve seat components 341. A passage hole 343 is formed on the inner side of the passage recess 342, extending axially through the main body portion 335. The passage hole 343 is parallel to the central axis of the main body portion 335. A passage hole 343 is formed on the bottom surface of all passage recesses 342.

[0202] The valve seat portion 334 has a plurality of valve seat constituent portions 351. These valve seat constituent portions 351 have the same shape. These valve seat constituent portions 351 are arranged at equal intervals along the circumference of the main body portion 335. These valve seat constituent portions 351 extend radially outward from the inner seat portion 333. The valve seat constituent portions 351 have the same shape as the valve seat constituent portion 341.

[0203] A passage recess 352 is formed on the inner side of each valve seat component 351. The passage recess 352 is formed by surrounding a portion of the valve seat component 351 and an inner seat portion 333. The passage recess 352 is axially recessed from the front end of the protruding side of the valve seat component 351 toward the main body portion 335. The bottom surface of the passage recess 352 is formed in the main body portion 335. A passage recess 352 is formed on the inner side of all valve seat components 351. A passage hole 353 is formed on the inner side of the passage recess 352, extending axially through the main body portion 335. The passage hole 353 is parallel to the central axis of the main body portion 335. A passage hole 353 is formed on the bottom surface of all passage recesses 352.

[0204] Here, the circumferential spacing of the main body portions 335 of the plurality of valve seat components 341 is the same as the circumferential spacing of the main body portions 335 of the plurality of valve seat components 351. The valve seat components 341 and 351 are arranged offset from each other by half a spacing along the circumferential direction of the main body portions 335. Furthermore, the passage hole 343 is disposed between adjacent valve seat components 351 in the circumferential direction of the main body portion 335. Therefore, the passage hole 343 is disposed outside the range of the valve seat portion 334. The passage hole 353 is disposed between adjacent valve seat components 341 in the circumferential direction of the main body portion 335. Therefore, the passage hole 353 is disposed outside the range of the valve seat portion 332.

[0205] On the valve seat component 276, a radially penetrating passage groove 355 is formed in the inner seat portion 331. The passage groove 355 opens between adjacent valve seat components 341 in the circumferential direction of the main body portion 335. The passage groove 355 also opens in the axial groove 323. Multiple passage grooves 355 are provided at equal intervals along the circumferential direction of the valve seat component 276. Figure 9 (Due to the cross-sectional shape, only one location is shown in the diagram).

[0206] The passage within the passage recess 352 and the passage within the passage hole 353 form a component passage 361. Multiple component passages 361 are provided at intervals along the circumference of the main body 335. The passage within the passage recess 342 and the passage within the passage hole 343 form a component passage 362. Multiple component passages 362 are provided at intervals along the circumference of the main body 335. The passage within the passage groove 355 forms a throttling orifice 356 (third pressure-reducing flow path) that narrows the flow path.

[0207] In the valve seat component 276, a sealing groove 365 is formed at the axial center of the outer periphery of the main body portion 335. The sealing groove 365 is recessed radially inward from the outer periphery of the main body portion 335. The sealing groove 365 is annular. An O-ring 275 is disposed within the sealing groove 365. With the inner seat portion 331 and the valve seat portion 332 facing the bottom 301 side of the cap component 280, the outer periphery of the valve seat component 276 is engaged with the cylindrical portion 302 of the cap component 280. In this state, the O-ring 275 seals the gap between the cylindrical portion 302 of the cap component 280 and the valve seat component 276.

[0208] The portion of the cap component 280 at the bottom 301 side, the O-ring 275, and the valve seat component 276 form a cap chamber 381. The cap chamber 381 is always in communication with the component passage 361 and the throttling orifice 356. A valve disc 277 is disposed within the cap chamber 381.

[0209] The valve disc 277 can be seated on or off the valve seat 332. The valve disc 277 opens and closes the component passage 362 by being seated on or off the valve seat 332. When the valve disc 277 is seated on the valve seat 332, the component passage 362 is closed. When the valve disc 277 is off the valve seat 332, the component passage 362 is opened. The spring member 279 presses the valve disc 277 against the valve seat 332 by its spring force. In the closed state, the valve disc 277 separates the component passage 362 from the cap chamber 381. In the open state, the valve disc 277 connects the component passage 362 and the cap chamber 381. Therefore, in the open state, the valve disc 277 connects the second chamber 20, the component passage 362, the cap chamber 381, the component passage 361, and the throttle orifice 256.

[0210] Valve disc 274 is a perforated circular disc. Valve disc 274 can sit on or leave valve seat portion 334. Valve disc 274 opens and closes component passage 361 by sitting on or leaving valve seat portion 334. When valve disc 274 is seated on valve seat portion 334, component passage 361 is closed. When valve disc 274 leaves valve seat portion 334, component passage 361 is opened. Valve disc 274 can be a common part with the same shape as valve disc 277.

[0211] The disc 273 is a perforated circular plate. The disc 273 abuts against the valve disc 274. The disc 273 can be a common part with the same shape as the disc 278.

[0212] The spring component 272 has a base plate portion 371 and a plurality of spring plate portions 372. The base plate portion 371 is a perforated circular plate. A mounting shaft portion 28A is fitted into the inner side of the base plate portion 371 in the radial direction. The plurality of spring plate portions 372 are disposed on the outer periphery of the base plate portion 371. The plurality of spring plate portions 372 are arranged at intervals along the circumference of the base plate portion 371. The plurality of spring plate portions 372 extend outward from the base plate portion 371 in the radial direction. The spring plate portions 372 are inclined relative to the base plate portion 371, such that the closer to the protruding front end side, the further away from the base plate portion 371 in the axial direction. The spring component 272 is mounted to the mounting shaft portion 28A such that the base plate portion 371 abuts against the disc 273, and the spring plate portions 372 extend from the base plate portion 371 towards the valve disc 274 in the axial direction of the base plate portion 371. Multiple spring plate portions 372 of spring component 272 abut against valve disc 274. Spring component 272 presses valve disc 274 against valve seat portion 334 of valve seat component 276 by its spring force. Spring component 272 can be configured as a common part with the same shape as spring component 279.

[0213] In the buffer device 1A, the passage in the large-diameter bore 606 of the piston 18, the passage in the passage grooves 29-31, 251, and 252 of the rod 21, the passage in the axial groove 102 of the pilot housing 56, and the passage in the axial groove 323 of the valve seat component 276 constitute a rod-side chamber 105A disposed on the side of the rod 21A. The rod-side chamber 105A communicates with the piston passage 39 via the throttle orifice 608 of the piston 18. The rod-side chamber 105A communicates with the passage in the outer passage recess 96 via the passage in the passage groove 90 of the pilot housing 56. The rod-side chamber 105A communicates with the throttle orifice 356 of the valve seat component 276.

[0214] In the low-speed damping force generating unit 261, the valve seat 332, valve disc 277, and spring component 279 constitute the valve mechanism 385. The component passage 362, the passage generated between the valve disc 277 and valve seat 332 when the valve is opened, and the cap chamber 381 constitute a flow path 386 communicating with the rod-side chamber 105A via the throttle orifice 356. The valve mechanism 385 is disposed in the flow path 386. When the piston 18 moves towards the second chamber 20, the valve mechanism 385 opens, and oil L flows into the second chamber 20, causing the flowing oil L to flow through the throttle orifice 356, the rod-side chamber 105A, the throttle orifice 608 of the piston 18, and the piston passage 39 to the first chamber 19. The valve mechanism 385 disposed in the flow path 386 generates damping force by controlling the flow of oil L in the flow path 386.

[0215] Flow path 386 and flow path 210 are arranged in parallel. The rigidity of the valve component 212 of the valve mechanism 42 located in flow path 210 is higher than the rigidity of the valve disc 277 of the valve mechanism 385 located in flow path 386. Therefore, the opening pressure of the valve component 212 of the valve mechanism 42 is higher than that of the valve disc 277. As a result, the valve mechanism 385 opens the valve before the valve component 212 of the valve mechanism 42 opens, thereby generating a damping force.

[0216] In the low-speed damping force generating section 261, the valve seat 334, valve disc 274, and spring component 272 constitute the valve mechanism 391. The cap chamber 381, component passage 361, and the passage generated between the valve disc 274 and valve seat 334 when the valve is opened constitute the flow path 401. The valve mechanism 391 is disposed in the flow path 401. When the piston 18 moves towards the first chamber 19, the valve mechanism 391 opens the valve, allowing the oil L flowing from the first chamber 19 through the piston passage 39, the throttle orifice 608 of the piston 18, the rod side chamber 105A, and the throttle orifice 356 to flow into the second chamber 20. The valve mechanism 391 disposed in the flow path 401 generates damping force by controlling the flow of oil in the flow path 401. The flow path cross-sectional area of ​​the throttle orifice 356 is smaller than that of the throttle orifice 608, but larger than that of the throttle orifice 173.

[0217] Flow path 401 is arranged in parallel with flow paths 162 and 181. The rigidity of valve component 161 of valve mechanism 41 in flow path 162 is higher than that of valve disc 274 of valve mechanism 391 in flow path 401. The rigidity of valve component 176A of valve mechanism 178A in flow path 181 is higher than that of valve disc 274 of valve mechanism 391 in flow path 401. Therefore, the opening pressure of valve component 161 and valve component 176A is higher than that of valve disc 274. As a result, valve mechanism 391 opens before valve component 161 of valve mechanism 41 and before valve component 176A of valve mechanism 178A, thereby generating a damping force.

[0218] Here, valve structure 225A can also be configured such that valve mechanism 42 is a structure without throttling orifice 213. That is, a structure in which no notch 211 is formed on disk 202 can also be used.

[0219] The hydraulic circuit diagram of valve structure 225A is as follows: Figure 10 As shown. Figure 10 As shown, in valve structure 225A, a throttling orifice 356 is provided branching from the flow path 181 between the throttling orifice 608 and the valve mechanism 178 and the throttling orifice 177. A low-speed damping force generating part 261 having valve mechanism 385 and valve mechanism 391 is provided between the throttling orifice 356 and the second chamber 20.

[0220] like Figure 10As shown in the hydraulic circuit diagram, the buffer device 1A has a flow path 162 connecting the first chamber 19 to the second chamber 20, a valve, i.e., valve mechanism 41, disposed in the flow path 162, and a throttling orifice 608 for which oil L flows in from the first chamber 19 and reduces the pressure of the oil L with a first intensity. Additionally, the buffer device 1A has a throttling orifice 173 disposed in parallel with the flow path 162 and having a smaller cross-sectional area than the throttling orifice 608, and a throttling orifice 356 disposed in parallel with the throttling orifice 173 downstream of the throttling orifice 608 and having a smaller cross-sectional area than the throttling orifice 608 and a larger cross-sectional area than the throttling orifice 173. Furthermore, the buffer device 1A has a pressure chamber 151 located downstream of the throttling orifice 173 and capable of applying a pressure in the valve-closing direction generated by the oil L to the valve mechanism 41 (see reference). Figure 6 The buffer device 1A includes a frequency sensing mechanism 185, which is installed in the pressure chamber 151 and deforms according to the internal pressure of the pressure chamber 151 to change the volume of the pressure chamber 151. In addition, the buffer device 1A has a valve mechanism 178A, which is located downstream of the throttle orifice 608 and is arranged in parallel with the throttle orifice 356, so that the incoming oil L can flow into the downstream second chamber 20.

[0221] In addition, the valve mechanism 41 of the buffer device 1A is arranged in parallel with the throttling orifice 608, and the throttling orifice 173 is arranged downstream of the throttling orifice 608 and connected in series with the throttling orifice 608.

[0222] In valve structure 225A, during the extension stroke of rod 21 moving towards the extension side, in the first micro-low speed region on the low-speed side of micro-low speed domain X1, the oil L from the first chamber 19 flows to the second chamber 20 via flow path 181 from the throttle orifice 177A at its end. Additionally, the oil L from the first chamber 19 also flows to the second chamber 20 via flow path 210 including throttle orifice 213. Therefore, valve structure 225A generates a damping force with throttle orifice characteristics in the first micro-low speed region on the low-speed side of micro-low speed domain X1.

[0223] In valve structure 225A, during the extension stroke of rod 21 moving towards the extension side, in the second micro-low speed region of micro-low speed domain X1, which is faster than the first micro-low speed region, oil L in the first chamber 19 flows from flow path 181 through throttle orifice 356 into the second chamber 20 while opening valve mechanism 391 in flow path 401. Therefore, valve structure 225A generates a damping force characteristic of the valve in the second micro-low speed region on the high-speed side of micro-low speed domain X1.

[0224] In this way, the valve structure 225A also generates a damping force characteristic of the valve within the low-speed range X1 of the extension stroke of the rod 21 moving towards the extension side.

[0225] In valve structure 225A, during the contraction stroke of rod 21 moving towards the contraction side, in the third micro-low speed region of micro-low speed range X4, the oil L in second chamber 20 flows to first chamber 19 via piston passage 40 including throttle orifice 213. Additionally, the oil L in second chamber 20 flows to first chamber 19 from throttle orifice 177A via flow path 181. Therefore, valve structure 225A generates a damping force with throttle orifice characteristics in the third micro-low speed region of micro-low speed range X4.

[0226] In valve structure 225A, during the contraction stroke of rod 21 moving towards the contraction side, in the fourth micro-low speed region of micro-low speed range X4, which is faster than the third micro-low speed region, the oil L in the second chamber 20 flows through the throttle orifice 356 and then through the flow path 181 to the first chamber 19 while opening valve mechanism 385 in flow path 386. Therefore, valve structure 225A generates a damping force characteristic of the valve in the fourth micro-low speed region on the high-speed side of micro-low speed range X4.

[0227] In this way, the valve structure 225A also generates a damping force characteristic of the valve within the low-speed range X4 of the contraction stroke of the rod 21 moving towards the contraction side.

[0228] The buffer device 1A of the second embodiment has a flow path 162 connecting a first chamber 19 inside the cylinder 2 to a second chamber 20, and a valve mechanism 41 provided in the flow path 162. Furthermore, the buffer device 1A has a throttling orifice 608 from which oil L flows in from the first chamber 19 and reduces the pressure of the oil L with a first intensity; a throttling orifice 173 provided in parallel with the flow path 162 and having a smaller cross-sectional area than the throttling orifice 608; and a throttling orifice 356 provided in parallel with the throttling orifice 173 and having a smaller cross-sectional area than the throttling orifice 608 and a larger cross-sectional area than the throttling orifice 173. Additionally, the buffer device 1A has a pressure chamber 151 located downstream of the throttling orifice 173 and capable of applying a pressure generated by the oil L in the valve-closing direction to the valve mechanism 41; and a frequency sensing mechanism 185 provided in the pressure chamber 151 and deforming according to the internal pressure of the pressure chamber 151 to change the volume of the pressure chamber 151. In addition, the buffer device 1A has a valve mechanism 178A, which is arranged in parallel with the throttle orifice 356, and can direct the incoming oil L to flow into the second chamber 20, which becomes the downstream.

[0229] The buffer device 1A has a valve mechanism 41, a valve mechanism 178A, and a throttling orifice 356, thus enabling it to mitigate changes in damping characteristics. The buffer device 1A also has a throttling orifice 608 and a throttling orifice 173, thus enabling detailed adjustment of the damping force characteristics and further mitigating changes in damping characteristics.

[0230] The buffer device 1A has a low-speed damping force generating unit 261, so it can generate a damping force with valve characteristics in the low-speed range X1 of the extension stroke and the low-speed range X4 of the contraction stroke.

[0231] Except for the micro-low speed damping force generating part 261, the structure of the buffer device 1A is the same as that of the buffer device 1 in the first embodiment. Therefore, it can achieve the same effect as the buffer device 1 in the first embodiment.

[0232] In the buffer device 1A, the throttle orifice 177A and throttle orifice 213 are eliminated. In other words, by setting the valve mechanism 178A and valve mechanism 42 to a structure without throttle orifices, the damping force of the valve characteristic can also be generated in the first micro-low speed region on the low speed side of the micro-low speed region X1 and the third micro-low speed region on the low speed side of the micro-low speed region X4.

[0233] [Third Implementation]

[0234] Next, mainly based on Figures 11-14 The third embodiment will be described focusing on the parts that differ from the first embodiment. It should be noted that the same parts as in the first embodiment are denoted by the same names and the same reference numerals.

[0235] like Figure 11 As shown, the buffer device 1B of the third embodiment has a valve structure 225B that is partially different from the valve structure 225 of the first embodiment instead of the valve structure 225. The valve structure 225B has a rod 21B that is partially different from the rod 21 of the first embodiment instead of the rod 21. A passage hole 451 is formed inside the rod 21B. The rod 21B has a main shaft portion 27B that is different from the main shaft portion 27 in that a portion of the passage hole 451 is formed inside, and a mounting shaft portion 28B that is different from the mounting shaft portion 28 in that the remaining portion of the passage hole 451 is formed inside.

[0236] The passage hole 451 has a radial hole portion 452, an axial hole portion 453, and a radial hole portion 454.

[0237] The radial hole 452 extends radially through the main shaft portion 27B. The radial hole 452 is formed on the axial side of the mounting shaft portion 28B of the main shaft portion 27B. The radial hole 452 opens in the first chamber 19.

[0238] An axial bore 453 extends axially from the center of a radial bore 452 in the radial direction of the main shaft 27B along the axial direction of the rod 21B. The axial bore 453 extends from the radial bore 452 to the end face of the mounting shaft 28B on the axial direction opposite to the main shaft 27B.

[0239] The radial hole 454 extends radially along the mounting shaft portion 28B. The radial hole 454 is formed in the portion between the main shaft portion 27B and the male thread 32 in the axial direction of the mounting shaft portion 28B. The radial hole 454 intersects with the axial hole 453.

[0240] An annular groove 455 is formed in the mounting shaft portion 28B, recessed radially inward from the outer periphery of the mounting shaft portion 28B. The groove 455 is formed in the portion between the main shaft portion 27B and the male thread 32 in the axial direction of the mounting shaft portion 28B. A radial hole 454 is opened on the bottom surface of the groove 455.

[0241] An axial groove 456 is formed in the mounting shaft portion 28B, recessed radially inward from the outer periphery of the mounting shaft portion 28B. The axial groove 456 extends axially along the mounting shaft portion 28B. The axial groove 456 extends from the passage groove 455 along the axial direction of the mounting shaft portion 28B towards the male thread 32, extending closer to it than the male thread 32. A plurality of axial grooves 456 are formed at intervals along the circumference of the mounting shaft portion 28B.

[0242] Valve structure 225B has a blocking member 461, which engages with the axial end of the axial bore 453 opposite to the radial bore 452. The blocking member 461 is fixed by engaging with the axial portion of the axial bore 453 opposite to the radial bore 452. The blocking member 461 blocks the axial portion of the axial bore 453 opposite to the radial bore 452.

[0243] Valve structure 225B has a piston 18B that is partially different from the piston 18 in the first embodiment, replacing the piston 18. Piston 18B has a piston body 33B that is partially different from the piston body 33, replacing the piston body 33. The piston body 33B is integrally formed. In the piston body 33B, an insertion hole 465 extending through the piston body 33B along its axial direction is formed at the radial center. The inner diameter of the insertion hole 465 is an inner diameter whose approximately total axial length throughout the piston body 33B is equal to the inner diameter of the fitting hole 611 of the piston body 33.

[0244] The structure between the piston 18B and the retainer 221 in valve structure 225B is different from the structure between the piston 18B and the retainer 221 in valve structure 225 of the first embodiment.

[0245] Valve structure 225B has, sequentially from the axial piston 18B side, a disc 51, a valve disc 52, multiple valve discs 473, multiple valve discs 474, and multiple discs 475 on the valve seat portion 47 and inner seat portion 48 side of piston 18B. Valve discs 473, 474, and discs 475 are all made of metal and are formed into a perforated circular plate of a certain thickness that can be fitted into the mounting shaft portion 28B of the inner rod 21B.

[0246] Valve disc 473 is a common part that is the same as valve disc 52.

[0247] The outer diameter of valve disc 474 is smaller than that of valve disc 473.

[0248] The outer diameter of disc 475 is smaller than that of valve disc 474.

[0249] Valve discs 52, 473, and 474 constitute a valve component 161B that can be seated on or away from the valve seat portion 47. The valve component 161B, together with the valve seat portion 47 of the piston 18B, constitutes the valve mechanism 41B (fourth valve) on the extension side.

[0250] Valve component 161B is the same as valve component 161 in the first embodiment. It abuts against valve disc 52 and valve seat 47, and opens and closes the opening of piston passage 39 by separating from and abutting against valve seat 47.

[0251] When valve component 161B opens away from valve seat 47, the oil L in the first chamber 19 flows into the second chamber 20 via piston passage 39 and the passage between valve component 161B and valve seat 47. In other words, valve component 161B is composed of valve discs 52, 473, and 474 that allow the oil L in the first chamber 19 to flow into the second chamber 20 via flow path 162 when it opens away from valve seat 47. When valve component 161B is seated on valve seat 47, it closes the opening on the second chamber 20 side of flow path 162.

[0252] On the side of the disc 475 opposite to the piston 18B in the axial direction, valve structure 225B is provided sequentially from the disc 475 side, including a valve component 176 consisting of multiple valve discs 60 and a valve disc 59, a disc 58, a valve component 171 consisting of multiple valve discs 57, a pilot housing 56, and a pilot valve 53, which are the same as those in the valve structure 225 of the first embodiment.

[0253] In valve structure 225B, the axial orientation and arrangement of valve component 176, disc 58, valve component 171, pilot housing 56, and pilot valve 53, and rod 21B, are opposite to the axial orientation and arrangement of valve component 176, disc 58, valve component 171, pilot housing 56, and pilot valve 53 of rod 21 in valve structure 225 of the first embodiment. For example... Figure 12 As shown, the axial groove 102 of the pilot housing 56 causes the axial position of the rod 21B to coincide with the passage groove 455 of the rod 21B. The passage in the axial groove 102 is connected to the passage in the passage groove 455 of the rod 21B.

[0254] Inside the pilot housing 56, a free valve 111, identical to the valve structure 225 of the first embodiment, is disposed opposite to the outer cylindrical portion 72 in the axial direction of the bottom 71.

[0255] Valve structure 225B, on the side of pilot valve 53 opposite to pilot housing 56 in the axial direction, includes a seat member 495, a disk 496, and an annular member 63, similar to that in the first embodiment, such that the mounting shaft portion 28B of rod 21B fits into its respective inner side. The seat member 495 can be made of metal, but the material is not limited. The seat member 495 is formed as a perforated circular plate that can fit into the mounting shaft portion 28B of rod 21B on its inner side. The disk 496 is also formed as a perforated circular plate that can fit into the mounting shaft portion 28B of rod 21B on its inner side.

[0256] The seat component 495 has a through hole 511 formed at its radial center, and the through hole 511 passes through the seat component 495 along the axial direction of the seat component 495. The seat component 495 has a bottom 512, an inner seat portion 513, and a valve seat portion 514 (first valve seat).

[0257] The bottom 512 is a perforated circular plate.

[0258] The inner seat 513 is a ring-shaped part that protrudes from the inner circumferential side of the bottom 512 toward the axial side of the bottom 512.

[0259] The valve seat portion 514 is formed in an annular shape on the outer side of the inner seat portion 513 in the radial direction. The valve seat portion 514 protrudes from the bottom 512 along the axial direction of the bottom 512 towards the same side as the inner seat portion 513.

[0260] A passage recess 515 is formed between the inner seat portion 513 and the valve seat portion 514. The passage recess 515 is formed by surrounding the inner seat portion 513 and the valve seat portion 514. The passage recess 515 is continuous throughout the entire circumference of the seat member 495. The passage recess 515 is recessed along the axial direction of the seat member 495 from the front end face of the protruding side of the inner seat portion 513 and the front end face of the protruding side of the valve seat portion 514. The bottom surface of the passage recess 515 is formed by the bottom 512.

[0261] A passage groove 516 is formed on the inner side of the inner seat 513 and the bottom 512 along the axial direction of the inner seat 513 side, extending through the inner seat 513 radially. The position of the passage groove 516 coincides with the passage recess 515 in the radial direction of the bottom 512, and it opens within the passage recess 515. A plurality of passage grooves 516 are formed at intervals along the circumference of the seat member 495. It should be noted that at least one passage groove 516 need to be provided on the seat member 495.

[0262] The through hole 511 has a large-diameter hole portion 521 and a small-diameter hole portion 522. The diameter of the large-diameter hole portion 521 is larger than that of the small-diameter hole portion 522. The small-diameter hole portion 522 is formed at the bottom 512. The large-diameter hole portion 521 is formed on the inner seat portion 513 and the portion of the bottom 512 on the axial side of the inner seat portion 513. In the seat member 495, the large-diameter hole portion 521 is formed to a depth greater than the bottom surface of the passage groove 516. In the through hole 511 of the seat member 495, the mounting shaft portion 28B of the rod 21B is fitted into the small-diameter hole portion 522. In the axial direction of the rod 21B, the position of the large-diameter hole portion 521 coincides with the axial groove 456 of the rod 21B. Thus, in the seat member 495, the passage in the large-diameter hole portion 521 communicates with the passage in the axial groove 456 of the rod 21B.

[0263] The passage in the passage hole 451 of the rod 21B, the passage in the passage groove 455 and the passage in the axial groove 456, the passage in the axial groove 102 of the pilot housing 56, and the passage in the large diameter hole 521 of the seat member 495 constitute the rod side chamber 105B.

[0264] The outer diameter of the valve disc 141 (first valve core) of the pilot valve 53 is slightly larger than the outer diameter of the valve seat portion 514 of the seat component 495. The valve disc 141 abuts against the valve seat portion 514, and opens and closes the passage in the passage recess 515 by separating from and abutting against the valve seat portion 514.

[0265] The valve disc 141 and the valve seat portion 514 of the seat component 495 together constitute the valve mechanism 532 (first valve). When the valve disc 141 opens away from the valve seat portion 514, it causes... Figure 11 The oil L in the first chamber 19 shown passes through the passage in the passage hole 451 of the rod 21B, the passage in the passage groove 455, the passage in the axial groove 456, and the seat component 495. Figure 12 The passage in the large-diameter bore 521, the passage in the passage groove 516 of the seat member 495, the passage in the passage recess 515 of the seat member 495, and the passage between the valve disc 141 and the valve seat 514 flow into the second chamber 20.

[0266] The passage in the passage hole 451 of the rod 21B, the passage in the passage groove 455 and the passage in the axial groove 456, the passage in the large diameter hole 521 of the seat member 495, the passage in the passage groove 516, the passage in the passage recess 515, and the passage between the valve disc 141 and the valve seat 514 constitute the passage. Figure 11The flow path 535 (first flow path) connecting the first chamber 19 and the second chamber 20 is shown. The flow path 535 is a flow path through which oil L, a fluid, flows out from one of the first chambers 19 and the second chamber 20, namely the first chamber 19. The rod-side chamber 105B is part of the flow path 535. The passage formed in the passage groove 516 of the inner seat portion 513 of the seat member 495 becomes a throttling orifice 536 (first pressure-reducing flow path) for reducing pressure in the narrowing flow path 535.

[0267] The flow path 535 serves as the extension-side flow path for the oil L, which is a fluid, to flow from the first chamber 19 to the second chamber 20 during the extension stroke of the piston 18B towards the first chamber 19. A valve mechanism 532, consisting of a valve seat 514 and a valve disc 141, is provided in the flow path 535. By opening and closing the flow path 535 using the valve disc 141, a damping force is generated to suppress the flow of oil L. In other words, the valve disc 141, provided in the flow path 535, suppresses the flow of oil L caused by the sliding of the piston 18B towards the extension side, thereby generating a damping force. Further, the valve disc 141 allows oil from one chamber (the first chamber 19) to flow into the second chamber 20.

[0268] The rod-side chamber 151B, which includes the passage in the passage hole 451 of the rod 21B, the passage in the passage groove 90 of the pilot housing 56 and the passage in the outer passage recess 96, as well as the throttle orifice 177, or the passage between the valve component 176 after valve opening and the outer valve seat portion 76, becomes part of the flow path 181B (second flow path) connected in parallel with the flow path 535, allowing oil L to flow from the first chamber 19 to the second chamber 20. In other words, the flow path 181B is the flow path from the first chamber 19 toward the valve mechanism 178 and through the throttle orifice 177 or the valve mechanism 178 after valve opening.

[0269] The valve structure 225B of the third embodiment has a flow path 535 that connects upstream of the first chamber 19 to a second chamber 20 that becomes the downstream side. The valve structure 225B is disposed in the flow path 535 and has a valve mechanism 532, which has a valve seat portion 514 and a valve disc 141 seated on or away from the valve seat portion 514. The valve structure 225B has a pressure chamber 151 capable of applying pressure to the valve disc 141 composed of oil L in the valve closing direction. The valve structure 225B has a flow path 181B, at least a portion of which is disposed parallel to the flow path 535 and connects upstream of the first chamber 19 to the second chamber 20 that becomes the downstream side. The valve structure 225B is disposed in the flow path 181B and has a valve mechanism 178, which is composed of an outer valve seat portion 76 and a valve component 176 seated on or away from the outer valve seat portion 76. Valve structure 225B has a communication passage 182 that connects the inner side of the outer valve seat portion 76, which is the upstream side, to the pressure chamber 151, which is the downstream side.

[0270] The hydraulic circuit diagram of valve structure 225B is as follows: Figure 13 As shown. Figure 13 As shown, in valve structure 225B, a flow path 535 is provided connecting the first chamber 19 and the second chamber 20. In flow path 535, a throttling orifice 536 is provided on the first chamber 19 side, and a valve mechanism 532 is provided on the second chamber 20 side. Additionally, in valve structure 225B, a flow path 181B is provided connecting the first chamber 19 and the second chamber 20. A valve mechanism 178 and a throttling orifice 177 are provided in flow path 181B. The valve mechanism 178 and the throttling orifice 177 are arranged in parallel. Furthermore, in valve structure 225B, a valve mechanism 172 and a throttling orifice 173 are branched from flow path 181B and arranged in parallel. The valve mechanism 172 and the throttling orifice 173 are connected to the pressure chamber 151 of valve opening control mechanism 186 (see reference 181B) via a connecting passage 182. Figure 6 The pressure in pressure chamber 151 acts on valve disc 141. Flow path 162B and flow path 210 are provided to connect the second chamber 20 and the first chamber 19. Valve mechanism 41B is provided in flow path 162B. Valve mechanism 42 and throttling orifice 213 are connected in parallel in flow path 210.

[0271] like Figure 13 As shown in the hydraulic circuit diagram, the valve structure 225B of the buffer device 1B has a flow path 535 connecting the first chamber 19 to the second chamber 20, a valve, i.e., valve mechanism 532, disposed in the flow path 535, and a throttle orifice 536 for which oil L flows in from the first chamber 19 and reduces the pressure of the oil L with a first intensity. Furthermore, the valve structure 225B has a throttle orifice 173 disposed in parallel with the flow path 535 and having a smaller cross-sectional area than the throttle orifice 536, and a throttle orifice 177 disposed in parallel with the throttle orifice 173 and having a smaller cross-sectional area than the throttle orifice 536 and a larger cross-sectional area than the throttle orifice 173. Additionally, the valve structure 225B has an opening valve control mechanism 186, which includes a pressure chamber 151 located downstream of the throttle orifice 173 and capable of applying a pressure generated by the oil L in the valve closing direction to the valve mechanism 532 (see reference). Figure 6 ), and a frequency sensing mechanism 185 (see reference) disposed in pressure chamber 151 and deforming and changing the volume of pressure chamber 151 according to the internal pressure of pressure chamber 151. Figure 6 In addition, valve structure 225B has valve mechanism 178, which is arranged in parallel with throttle orifice 177, enabling the incoming oil L to flow into the downstream second chamber 20.

[0272] In addition, the valve mechanism 532 of the valve structure 225B is located downstream of the throttle orifice 536 and is connected in series with the throttle orifice 536, while the throttle orifice 173 is connected in parallel with the throttle orifice 536.

[0273] In addition, the valve structure 225B is arranged in parallel with the throttling orifice 536, and has a flow path 162B that connects the first chamber 19 to the second chamber 20, and a valve, i.e., valve mechanism 41B, provided in the flow path 162B.

[0274] In addition, the piston 18B of the valve structure 225B has a valve mechanism 41B that restricts the flow of oil L from the first chamber 19 to the second chamber 20.

[0275] Next, refer to Figure 14 The characteristic curve of damping force versus piston speed shown illustrates the operation of valve structure 225B. Figure 14 In the diagram, solid lines Y11, Y12, and Y13 represent the characteristic curves of valve structure 225B.

[0276] During the extension stroke of rod 21 as it moves toward the extension side, when the piston speed is in a low-speed range X11 that is slower than the 11th specified speed and the piston frequency is lower than the specified frequency, the oil L from the first chamber 19 flows into the pressure chamber 151 through the passage in the passage hole 451 of rod 21B, the rod side chamber 151B, the passage in the passage groove 90 of the pilot housing 56, the passage in the outer passage recess 96, and the connecting passage 182 including the throttle orifice 173.

[0277] During the extension stroke of this low-frequency input in the micro-low speed range X11, the amplitude of piston 18 is large. Therefore, the amount of oil L flowing into pressure chamber 151 is large, and the deformation of free valve 111 is large. Thus, in the initial stage of the extension stroke, the deformed free valve 111 immediately abuts against the recess 82, limiting its further deformation, and oil L does not flow from the first chamber 19 into pressure chamber 151. It should be noted that at this time, variable chamber 152 discharges oil L into the second chamber 20 through the passage in the outer through hole 87. During the extension stroke of this low-frequency input in the micro-low speed range X11, as described above, when free valve 111 abuts against the recess 82, limiting its further deformation, the volume of pressure chamber 151 does not increase. Therefore, the pressure in pressure chamber 151 rises, limiting the opening of valve disc 141 of valve mechanism 532. That is, valve disc 141 of valve mechanism 532 is not open.

[0278] Therefore, during the extension stroke at low-frequency input in the micro-low speed range X11, the oil L from the first chamber 19 flows to the second chamber 20 via the passage in the rod-side chamber 151B containing the passage hole 451 of the rod 21B, the passage in the passage groove 90 of the pilot housing 56, the passage in the outer passage recess 96, and the throttle orifice 177, i.e., via the flow path 181B, from the throttle orifice 177 at the end of the flow path 181B. The oil L from the first chamber 19 also flows to the second chamber 20 via the flow path 210 containing the throttle orifice 213. Therefore, at low-frequency input in the micro-low speed range X11, such as Figure 14As shown by the solid line Y11, this represents the damping force that generates the orifice characteristic. Therefore, during the extension stroke at low-frequency input in the micro-low speed domain X11, the rate of increase of the damping force relative to the piston speed is higher than the rate of increase of the piston speed.

[0279] During the extension stroke, when the piston speed is in the low-speed range X11, which is slower than the 11th specified speed, and the piston frequency is a high-frequency input above the specified frequency, the oil L from the first chamber 19 flows to the pressure chamber 151 via the flow path 181B and the connecting path 182, which branches off from the middle of the flow path 181B and includes the throttle orifice 173.

[0280] During the extension stroke at high-frequency input in this low-speed range X11, the amplitude of piston 18 is small. Therefore, the amount of oil L flowing into pressure chamber 151 is small, and the deformation of free valve 111 is small. Therefore, when oil L from first chamber 19 is introduced into pressure chamber 151 from flow path 181B via connecting path 182, depending on the situation, free valve 111, which is previously formed into a flat plate and abuts against seat 80, elastically deforms into recess 82 in a state where the communication between pressure chamber 151 and variable chamber 152 is blocked, thereby increasing the volume of pressure chamber 151, while simultaneously discharging oil L from variable chamber 152 through passage in outer through hole 87 to second chamber 20.

[0281] Although oil L is introduced from the first chamber 19 to the pressure chamber 151 while the free valve 111 is deformed, the amount of oil L introduced from the first chamber 19 to the pressure chamber 151 is small. Therefore, the deformation of the free valve 111 is small, and it does not become abut against the recess 82 and restrict deformation as it would during low-frequency input. In this way, by flexing the free valve 111, the pressure rise in the pressure chamber 151 is suppressed, and the valve disc 141 can be opened more easily.

[0282] Therefore, during the extension stroke at high-frequency input in the low-speed range X11, the oil L from the first chamber 19, in addition to flowing through the flow path 181B and through the throttle orifice 177 at its end to the second chamber 20, also flows through the flow path 535, simultaneously with opening the valve mechanism 532, that is, simultaneously with causing the valve disc 141 to leave the valve seat portion 514, to the second chamber 20. Therefore, as... Figure 14 As shown by the solid line Y12, a damping force characteristic of the valve is generated during the extension stroke at high-frequency input in the micro-low speed domain X11. Therefore, the damping force decreases during the extension stroke at high-frequency input in the micro-low speed domain X11 compared to the extension stroke at low-frequency input. Furthermore, regarding the characteristics of the damping force relative to piston speed during the extension stroke at high-frequency input in the micro-low speed domain X11, the rate of increase of the damping force relative to piston speed is lower than during the extension stroke at low-frequency input.

[0283] During the extension stroke, when the piston speed is above the 11th specified speed and below the 12th specified speed which is faster than the 11th specified speed, and when the piston frequency is below the specified frequency, the oil L from the first chamber 19 flows from the flow path 181B through the connecting path 182 containing the throttle orifice 173 to the pressure chamber 151, just as in the low-frequency input of the micro low-speed domain X11.

[0284] During the extension stroke of this low-frequency input in the low-speed range X12, similar to the low-frequency input in the micro-low-speed range X11, the amplitude of piston 18 is large. Therefore, the amount of oil L flowing into pressure chamber 151 is large, and the deformation of free valve 111 is large. Thus, in the initial stage of the extension stroke, the deformed free valve 111 immediately abuts against the recess 82, limiting its further deformation, and the volume of pressure chamber 151 does not increase. During the extension stroke of this low-frequency input in the low-speed range X12, because the volume of pressure chamber 151 does not increase, the pressure in pressure chamber 151 rises, inhibiting the opening of valve disc 141 of valve mechanism 532. That is, during the extension stroke of the low-frequency input in the low-speed range X12, valve disc 141 of valve mechanism 532 also does not open.

[0285] During the extension stroke at low-frequency input in the low-speed range X12, the flow rate of oil L flowing from the first chamber 19 to the flow path 181B is greater than that during the extension stroke at low-frequency input in the micro-low-speed range X11. Therefore, oil L flows from the first chamber 19 into the flow path 181B, simultaneously opening the valve mechanism 178 and simultaneously causing the valve component 176 to move away from the outer valve seat 76, into the second chamber 20. Therefore, as... Figure 14 As shown by the solid line Y11, the damping force that generates the valve characteristics. Therefore, during the extension stroke at low-frequency input in the low-speed domain X12, the rate of increase of the damping force relative to the piston speed is lower than that during the extension stroke at low-frequency input in the micro-low-speed domain X11, in terms of the characteristics of the damping force relative to the piston speed.

[0286] During the extension stroke, when the piston speed is above the 11th specified speed and below the 12th specified speed which is faster than the 11th specified speed, and when the piston frequency is above the specified frequency, the oil L from the first chamber 19 flows to the pressure chamber 151 via the flow path 181B and the connecting path 182 containing the throttle orifice 173, just like when the high-frequency input is in the micro low-speed domain X11.

[0287] During the extension stroke at high frequency input in this low-speed range X12, similar to the high-frequency input in the micro-low-speed range X11, the amplitude of piston 18 is small. Therefore, the amount of oil L flowing into pressure chamber 151 is small, and the deformation of free valve 111 is minimal. Thus, by flexing free valve 111, the pressure rise in pressure chamber 151 can be suppressed, and valve disc 141 can be easily opened.

[0288] Therefore, during the extension stroke at high-frequency input in the low-speed range X12, the oil L from the first chamber 19 flows into the second chamber 20 in flow path 181B, simultaneously opening the valve mechanism 178, that is, simultaneously causing the valve component 176 to leave the outer valve seat 76. At the same time, the oil L from the first chamber 19 flows into the second chamber 20 in flow path 535, simultaneously opening the valve mechanism 532, that is, simultaneously causing the valve disc 141 to leave the valve seat 514. Therefore, during the extension stroke at high-frequency input in the low-speed range X12, as... Figure 14 As shown by the solid line Y12, the damping force decreases compared to the low-frequency input in the low-speed domain X12. Furthermore, during the extension stroke at the high-frequency input in the low-speed domain X12, the rate of increase of the damping force relative to piston speed is lower than that at the low-frequency input in the micro-low-speed domain X11. However, during the extension stroke at the high-frequency input in the low-speed domain X12, the rate of increase of the damping force relative to piston speed is the same as that during the extension stroke at the high-frequency input in the micro-low-speed domain X11.

[0289] During the extension stroke, when the piston speed is above the 12th specified speed and below the 13th specified speed (which is faster than the 12th specified speed) and the piston frequency is below the specified frequency (low-frequency input), the extension stroke is the same as that during the low-frequency input in the low-speed range X12. The oil L from the first chamber 19 flows in the flow path 181B and flows to the pressure chamber 151 via the connecting path 182 containing the throttle orifice 173.

[0290] During the extension stroke of the low-frequency input in the mid-speed range X13, similar to the low-frequency input in the low-speed range X12, the amplitude of piston 18 is large. Therefore, the amount of oil L flowing into pressure chamber 151 is large, and the deformation of free valve 111 is large. Thus, in the initial stage of the extension stroke, the deformed free valve 111 immediately abuts against the recess 82, limiting its further deformation, and the volume of pressure chamber 151 does not increase. During the extension stroke of the low-frequency input in the mid-speed range X13, the volume of pressure chamber 151 does not increase. Therefore, although the pressure in pressure chamber 151 increases, in terms of the force (hydraulic pressure) acting on valve disc 141, the force applied in the opening direction from flow path 535 is greater than the force applied in the closing direction from pressure chamber 151. Therefore, during the low-frequency input in the mid-speed range X13, as the piston speed increases, valve disc 141 of valve mechanism 532 opens further away from valve seat portion 514 than described above. As a result, in addition to the flow into the second chamber 20 through the flow path 181B that opens the valve mechanism 178, more oil L flows into the second chamber 20 through the flow path 535, which includes the passage between the valve disc 141 and the valve seat portion 514, thus further suppressing the rise in damping force. Therefore, as Figure 14As shown by the solid line Y11, in terms of the characteristics of damping force relative to piston speed, the rate of increase of damping force relative to piston speed is lower than the extension stroke at low frequency input in the low speed domain X12.

[0291] During the extension stroke, in the medium speed range X13 where the piston speed is above the 12th specified speed and slower than the 13th specified speed, and at a high frequency input where the piston frequency is above the specified frequency, the oil L from the first chamber 19 flows in the flow path 181B, just like in the high frequency input of the low speed range X12, and flows to the pressure chamber 151 via the connecting path 182 containing the throttle orifice 173.

[0292] During the extension stroke at high-frequency input in the medium-speed range X13, the amplitude of piston 18 is small, similar to that at high-frequency input in the low-speed range X12. Therefore, the amount of oil L flowing into pressure chamber 151 is small, and the deformation of free valve 111 is minimal. Thus, by flexing free valve 111, the pressure rise in pressure chamber 151 can be suppressed, and valve disc 141 can be easily opened.

[0293] Therefore, during the extension stroke at high-frequency input in the mid-speed range X13, the oil L from the first chamber 19 flows into the second chamber 20 through flow path 181B, simultaneously opening the valve mechanism 178 and separating the valve component 176 from the outer valve seat 76. At the same time, the oil L from the first chamber 19 flows into the second chamber 20 through flow path 535, simultaneously opening the valve mechanism 532 and separating the valve disc 141 from the valve seat 514. Here, during the extension stroke at high-frequency input in the mid-speed range X13, because a throttling orifice 536 is provided upstream of the valve mechanism 532, the flow rate of the oil L flowing through the valve mechanism 532 is limited by the throttling orifice 536. Therefore, during the extension stroke at high-frequency input in the mid-speed range X13, as... Figure 14 As shown by the solid line Y12, in terms of the characteristics of damping force relative to piston speed, the rate of increase of damping force relative to piston speed is higher than the extension stroke at high frequency input in the low speed domain X12.

[0294] During the extension stroke, when the piston speed is in the high-speed range X14 (above the 13th specified speed) and the piston frequency is below the specified frequency (low-frequency input), the extension stroke is the same as that during the low-frequency input in the medium-speed range X13. The oil L from the first chamber 19 flows in the flow path 181B and flows to the pressure chamber 151 via the connecting path 182 containing the throttle orifice 173.

[0295] During the extension stroke of the low-frequency input in the high-speed domain X14, similar to the low-frequency input in the medium-speed domain X13, the amplitude of piston 18 is large. Therefore, the amount of oil L flowing into pressure chamber 151 is large, and the deformation of free valve 111 is large. Thus, in the initial stage of the extension stroke, the deformed free valve 111 immediately abuts against the recess 82, limiting its further deformation, and the volume of pressure chamber 151 does not increase. During the extension stroke of the low-frequency input in the high-speed domain X14, the volume of pressure chamber 151 does not increase. Therefore, although the pressure in pressure chamber 151 increases, in terms of the force (hydraulic pressure) acting on valve disc 141, the force applied in the opening direction from flow path 535 is greater than the force applied in the closing direction from pressure chamber 151. Therefore, during the low-frequency input in the high-speed domain X14, as the piston speed increases, the valve component 161 of valve mechanism 532 moves further away from valve seat 514 and opens further than described above. Furthermore, at low-frequency input in the high-speed domain X14, valve mechanism 41B opens; in other words, valve component 161B moves away from valve seat 47 and opens. As a result, in addition to flow into the second chamber 20 via flow path 181B (which opens valve mechanism 178) and flow into the second chamber 20 via flow path 535 (which includes the passage between valve component 161B and valve seat 514), oil L flows through flow path 162 between valve component 161B and valve seat 47. Therefore, regarding the characteristics of damping force relative to piston speed, as... Figure 14 As shown by the solid line Y11, the rate of increase of the damping force relative to the increase of the piston speed is the same as the extension stroke at the low-frequency input of the mid-speed domain X13.

[0296] During the extension stroke, when the piston speed is in the high-speed range X14 (above the 13th specified speed) and the piston frequency is above the specified frequency (high-frequency input), the oil L from the first chamber 19 flows in the flow path 181B, just like the high-frequency input in the medium-speed range X13, and flows to the pressure chamber 151 via the connecting path 182 containing the throttle orifice 173.

[0297] During the extension stroke at high-frequency input in the high-speed domain X14, the amplitude of piston 18 is small, similar to that in the medium-speed domain X13. Therefore, the amount of oil L flowing into pressure chamber 151 is small, and the deformation of free valve 111 is minimal. Thus, by flexing free valve 111, the pressure rise in pressure chamber 151 can be suppressed, and valve disc 141 can be easily opened.

[0298] Therefore, during the extension stroke at high-frequency input in the high-speed domain X14, the oil L from the first chamber 19 flows into the second chamber 20 through flow path 181B, simultaneously opening the valve mechanism 178 and separating the valve component 176 from the outer valve seat 76. At the same time, the oil L from the first chamber 19 flows into the second chamber 20 through flow path 535, simultaneously opening the valve mechanism 532 and separating the valve component 161B from the valve seat 514. Furthermore, during high-frequency input in the high-speed domain X14, the oil L from the first chamber 19 flows into the second chamber 20 through flow path 162, simultaneously opening the valve mechanism 41B and separating the valve component 161B from the valve seat 47. Therefore, as... Figure 14 As shown by the solid line Y12, during the extension stroke at high-frequency input in the high-speed domain X14, the rate of increase of the damping force relative to the piston speed is lower than that during the extension stroke at high-frequency input in the mid-speed domain X13, in terms of the characteristics of the damping force relative to the piston speed.

[0299] During the contraction stroke of rod 21 moving towards the contraction side, in the micro-low speed range X15 where the piston speed is slower than the 15th specified speed, oil L from the second chamber 20 flows into the first chamber 19 via the piston passage 40 on the contraction side and the throttle orifice 213 of the valve component 212 of the valve mechanism 42. Simultaneously, oil L from the second chamber 20 flows into the flow path 181B through the throttle orifice 177 and flows into the first chamber 19 via the flow path 181B. At the same time, oil L from the second chamber 20 flows through the passage in the outer through-hole 87 and the variable chamber 152, simultaneously opening the check valve 155, from the pressure chamber 151, the connecting passage 182, through the throttle orifice 173, and via the flow path 181B into the first chamber 19. Therefore, during the contraction stroke in the micro-low speed range X15, a damping force characteristic of the throttle orifice is generated. Therefore, in the contraction stroke of X15 in the low-speed range, the rate of increase of the damping force is higher than the rate of increase of the piston speed in terms of the characteristics of the damping force relative to the piston speed.

[0300] During the contraction stroke in the low-speed range X16, where the piston speed is above the 15th specified speed but below the 16th specified speed (which is faster than the 15th specified speed), the oil L flowing from the second chamber 20 through the passage in the outer through-hole 87 and the variable chamber 152, while opening the check valve 155, flows through the pressure chamber 151 and the connecting passage 182. Simultaneously, this opens the valve mechanism 172 at the end of the connecting passage 182, that is, while causing the valve component 171 to leave the intermediate valve seat 75, and then flows through the flow path 181B to the first chamber 19. Therefore, during the contraction stroke in the low-speed range X16, as... Figure 14 As shown by the solid line Y13, the damping force that generates the valve characteristics. Therefore, in the contraction stroke of the low-speed range X16, the rate of increase of the damping force relative to the piston speed is lower than that in the contraction stroke of the micro-low-speed range X15, in terms of the characteristics of the damping force relative to the piston speed.

[0301] During the contraction stroke of the medium-high speed range X17, where the piston speed is above the 16th specified speed, similar to the contraction stroke of the low-speed range X16, oil L flows from the second chamber 20 to the first chamber 19 via flow path 181B while simultaneously opening the valve mechanism 172. During the contraction stroke of the medium-high speed range X17, simultaneously, oil L is introduced from the second chamber 20 into the piston passage 40 on the contraction side, and flows into the first chamber 19 while simultaneously opening the valve mechanism 42, that is, while simultaneously causing the valve component 212 to leave the valve seat portion 49. Therefore, as... Figure 14 As shown by the solid line Y13, in the contraction stroke of the medium-high speed domain X17, in terms of the characteristics of the damping force relative to the piston speed, the rate of increase of the damping force relative to the piston speed is lower than that in the contraction stroke of the low speed domain X16.

[0302] The buffer device 1B of the third embodiment has a flow path 535 connecting a first chamber 19 inside the cylinder 2 to a second chamber 20, and a valve mechanism 532 disposed in the flow path 535. Furthermore, the buffer device 1B has a throttling orifice 536 from which oil L flows in from the first chamber 19 and reduces the pressure of the oil L with a first intensity; a throttling orifice 173 disposed in parallel with the flow path 535 and having a smaller cross-sectional area than the throttling orifice 536; and a throttling orifice 177 disposed in parallel with the throttling orifice 173 and having a smaller cross-sectional area than the throttling orifice 536 and a larger cross-sectional area than the throttling orifice 173. Additionally, the buffer device 1B has a pressure chamber 151 located downstream of the throttling orifice 173 and capable of applying a pressure generated by the oil L in the valve-closing direction to the valve mechanism 532; and a frequency sensing mechanism 185 disposed in the pressure chamber 151 and deforming according to the internal pressure of the pressure chamber 151 to change the volume of the pressure chamber 151. In addition, the buffer device 1B has a valve mechanism 178, which is arranged in parallel with the throttle orifice 177, and can direct the incoming oil L to the second chamber 20, which becomes the downstream.

[0303] The buffer device 1B has a valve mechanism 532, a valve mechanism 178, and a throttling orifice 177, thus enabling it to mitigate changes in damping characteristics. The buffer device 1B also has a throttling orifice 536 and a throttling orifice 173, thus enabling detailed adjustment of the damping force characteristics and further mitigating changes in damping characteristics.

[0304] The valve structure 225B of the buffer device 1B has a flow path 535 that connects upstream of the first chamber 19 to a second chamber 20 that is downstream, and a valve disc 141 disposed in the flow path 535 and having a valve seat portion 514 and a valve disc 141 seated on or away from the valve seat portion 514. Furthermore, the valve structure 225B has a pressure chamber 151 capable of applying pressure generated by the oil L in the valve closing direction to the valve disc 141, and a flow path 181B that is at least partially disposed parallel to the flow path 535 and connects upstream of the first chamber 19 to the second chamber 20 that is downstream. Additionally, the valve structure 225B has a valve mechanism 178 disposed in the flow path 181B and consisting of an outer valve seat portion 76 and a valve component 176 seated on or away from the outer valve seat portion 76, and a communication path 182 connecting the inner side of the upstream outer valve seat portion 76 to the downstream pressure chamber 151. Therefore, the buffer device 1B can mitigate changes in damping characteristics.

[0305] In the buffer device 1B, the valve mechanism 532 of the valve structure 225B is located downstream of the throttling orifice 536 and is connected in series with the throttling orifice 536, while the throttling orifice 173 is connected in parallel with the throttling orifice 536. Therefore, the buffer device 1B can adjust the damping force characteristics in more detail and can further mitigate changes in attenuation characteristics.

[0306] Furthermore, the valve structure 225B of the buffer device 1B has a flow path 162B arranged in parallel with the throttle orifice 536 and communicating from the first chamber 19 to the second chamber 20, and a valve, i.e., valve mechanism 41B, provided in the flow path 162B. Therefore, the buffer device 1B can adjust the damping force characteristics in more detail and can further mitigate changes in attenuation characteristics.

[0307] In addition, the valve structure 225B of the buffer device 1B is as follows: Figure 11 As shown, piston 18B has a valve mechanism 41B that restricts the flow of oil L from the first chamber 19 to the second chamber 20. Therefore, the damping device 1B can adjust the damping force characteristics in more detail, and can further mitigate changes in damping characteristics.

[0308] Alternatively, the extension and contraction sides can be reversed, and the structure of rods 21, 21A, and 21B, which are respectively set in buffer devices 1, 1A, and 1B, can be set as a whole on rods 21, 21A, and 21B.

[0309] Alternatively, the above structure can be installed inside the attenuation valve housing (cylinder) that is integral with or separate from the outside of the buffer device.

[0310] Industrial availability

[0311] According to the above-described method of the present invention, a buffer device that can mitigate changes in attenuation characteristics can be provided. Therefore, it has high industrial applicability.

[0312] Explanation of reference numerals in the attached figures

[0313] 1, 1A, 1B… Buffer device, 2… Cylinder, 18, 18B… Piston (segmentation component), 19… First chamber, 20… Second chamber, 21, 21A, 21B… Rod, 41, 532… Valve mechanism (first valve), 41B… Valve mechanism (fourth valve), 47… Valve seat (first valve seat), 56… Pilot housing (partition wall component), 71… Bottom, 72… Outer cylindrical part (cylinder), 76… Outer valve seat (second valve seat), 87… Through hole, 111… Free valve (diaphragm component), 141… Valve disc (first valve core), 151… Pressure chamber, 161… Valve component (First valve core), 162, 535… flow path (first flow path), 172… valve mechanism (third valve), 173… throttle orifice (second pressure reducing flow path), 177, 356… throttle orifice (third pressure reducing flow path), 176… valve component (second valve core), 178… valve mechanism (second valve), 181, 181B… flow path (second flow path), 182… connecting path, 185… frequency sensing mechanism (volume change mechanism), 225, 225A, 225B… valve structure, 608… throttle orifice (first pressure reducing flow path, narrowest part), 536… throttle orifice (first pressure reducing flow path).

Claims

1. A buffer device comprising: cylindrical body; A dividing component that divides the interior of the cylinder into a first chamber and a second chamber; A first flow path connects the first chamber to the second chamber; The first valve is a valve disposed in the first flow path; A first pressure-reducing flow path flows into the first chamber and reduces the pressure of the fluid with a first intensity; The second pressure-reducing flow path is arranged in parallel with the first flow path, and its cross-sectional area is smaller than that of the first pressure-reducing flow path; The third pressure-reducing flow path is arranged in parallel with the second pressure-reducing flow path, and its cross-sectional area is smaller than that of the first pressure-reducing flow path and larger than that of the second pressure-reducing flow path. The pressure chamber, located downstream of the second pressure-reducing flow path, is capable of applying a pressure generated by the fluid in the valve-closing direction to the first valve; A volume change mechanism is disposed in the pressure chamber and deforms according to the internal pressure of the pressure chamber, thereby changing the volume of the pressure chamber through the internal pressure. as well as The second valve, which is connected in parallel with the third pressure-reducing flow path, allows the incoming fluid to flow into the second chamber, which becomes the downstream.

2. The buffer device according to claim 1, wherein, The first valve is connected in parallel with the first pressure-reducing flow path. The second pressure-reducing flow path is located downstream of the first pressure-reducing flow path and is connected in series with the first pressure-reducing flow path.

3. The buffer device according to claim 1, wherein, The first valve is located downstream of the first pressure-reducing flow path and is connected in series with the first pressure-reducing flow path. The second pressure-reducing flow path is connected in parallel with the first pressure-reducing flow path.

4. The buffer device according to claim 3, wherein, The buffer device also has: A second flow path, which is connected in parallel with the first pressure-reducing flow path, connects from the first chamber to the second chamber; and The third valve is a valve located in the second flow path.

5. A buffer device comprising: A cylindrical body with a bottom; A piston that divides the interior of the cylinder into a first chamber and a second chamber; A rod that secures the piston; and Valve structure, The valve structure has the following characteristics: A first flow path, which connects upstream of the first chamber to the second chamber, which becomes the downstream side; A first valve is disposed in the first flow path and has a first valve seat and a first valve core that is seated in or away from the first valve seat; A pressure chamber that can apply pressure to the first valve core generated by the fluid in the valve closing direction; The second flow path, at least a portion of which is arranged in parallel with the first flow path, connects the first chamber upstream to the second chamber downstream; A second valve, disposed in the second flow path, comprises a second valve seat and a second valve core disposed on or separated from the second valve seat; and A connecting passage connects the inner side of the second valve seat on the upstream side to the pressure chamber on the downstream side.

6. The buffer device according to claim 5, wherein, The second flow path is disposed on the surface or inside the rod. The pressure chamber is formed by a bottomed cylindrical partition component having a bottom and a cylindrical section. The second valve seat is disposed on the bottom side facing the second chamber.

7. The buffer device according to claim 6, wherein, The second valve also has a throttling orifice, the cross-sectional area of ​​which is smaller than the narrowest part of the second flow path, so as to always allow the fluid to flow.

8. The buffer device according to claim 7, wherein, The partition component also has a third valve disposed between the second valve seat and the second valve core, which further restricts the flow of fluid compared to the throttling orifice.

9. The buffer device according to claim 6, wherein, The bottom of the partition component has a through hole on the side of the bottom facing the second chamber that is radially outer of the second valve seat, allowing it to communicate with the pressure chamber. A membrane component is provided on the partition wall component, which blocks the through hole from the inside of the pressure chamber and is capable of changing the volume of the pressure chamber by the pressure.

10. The buffer device according to claim 5 or 6, wherein, The piston has a fourth valve that restricts the flow of fluid from the first chamber to the second chamber.

Images