Shock absorber

Abstract

A shock absorber according to the present invention has: a first damping force generation mechanism provided in a first passage; a second damping force generation mechanism provided in a second passage that is parallel to the first passage; and a third damping force generation mechanism provided in a third passage that is parallel to the first passage and the second passage. The third damping force generation mechanism operates earlier than the first damping force generation mechanism and the second damping force generation mechanism when the moving speed of a piston is a first speed. The second damping force generation mechanism operates in a state in which the third damping force generation mechanism is operating when the moving speed of the piston is a second speed that is faster than the first speed. The first damping force generation mechanism operates in a state in which the second damping force generation mechanism is operating when the moving speed of the piston is a third speed that is faster than the second speed.

Description

Shock absorber

[0001] The present disclosure relates to a shock absorber. The present application claims priority based on Japanese Patent Application No. 2025-049327 filed in Japan on March 25, 2025, the content of which is incorporated herein by reference.

[0002] Some shock absorbers are provided with a variable volume chamber, so that the damping force becomes variable in response to the piston frequency, which is the frequency of axial movement of the piston (see, for example, Patent Document 1).

[0003] International Publication No. WO 2023 / 037722

[0004] There is a demand for shock absorbers to generate damping force more satisfactorily.

[0005] Accordingly, an object of the present disclosure is to provide a shock absorber that can generate damping force more satisfactorily.

[0006] To achieve the above objective, a shock absorber according to a first aspect of the present disclosure includes: a cylinder in which a working fluid is sealed; a piston movably provided within the cylinder and dividing the cylinder into a first chamber and a second chamber; a piston rod connected to the piston and extending outside the cylinder; a first damping force generating mechanism provided in a first passage through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the first passage; a second damping force generating mechanism provided in a second passage arranged in parallel with the first passage through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the second passage; and a third damping force generating mechanism provided in a third passage arranged in parallel with the first and second passages through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the third passage. The third damping force generating mechanism operates before the first damping force generating mechanism and the second damping force generating mechanism when the piston is moving at a first speed. The second damping force generating mechanism operates when the third damping force generating mechanism is operating at a second speed in which the piston's movement speed is faster than the first speed. The first damping force generating mechanism operates when the second damping force generating mechanism is operating at a third speed in which the piston's movement speed is faster than the second speed.

[0007] A second embodiment of the shock absorber according to the present disclosure includes a cylinder through which a working fluid is sealed; a piston movably provided within the cylinder and dividing the cylinder into a first chamber and a second chamber; a piston rod connected to the piston and extending outside the cylinder; a first damping force generating mechanism provided in a first passage through which the working fluid flows as a result of the movement of the piston, for adjusting the flow of the working fluid moving within the first passage; a second damping force generating mechanism provided in a second passage arranged in parallel with the first passage through which the working fluid flows as a result of the movement of the piston, for adjusting the flow of the working fluid moving within the second passage; and a third damping force generating mechanism provided in a third passage arranged in parallel with the first and second passages through which the working fluid flows as a result of the movement of the piston, for adjusting the flow of the working fluid moving within the third passage. The second damping force generating mechanism includes a case member fixed to the piston rod and in which a part of the second passage is formed; a first valve positioned in contact with one axial direction of the case member and adjusting the flow of the working fluid in the second passage; a second valve positioned in contact with the other axial direction of the case member and adjusting the flow of the working fluid in the second passage; and a variable valve provided between the case member and the second valve, which contacts the second valve to form a variable volume chamber between itself and the second valve, and opens and closes according to the flow of the working fluid. The third damping force generating mechanism includes a seat member fixed to the piston rod and in which a part of the third passage is formed; and a third valve that contacts the seat member and opens when separated from the seat member by the flow of the working fluid.

[0008] A third embodiment of the shock absorber according to the present disclosure includes a cylinder through which a working fluid is sealed; a piston movably provided within the cylinder and dividing the cylinder into a first chamber and a second chamber; a piston rod connected to the piston and extending outside the cylinder; a first damping force generating mechanism provided in a first passage through which the working fluid flows as a result of the movement of the piston, for adjusting the flow of the working fluid moving within the first passage; a second damping force generating mechanism provided in a second passage arranged in parallel with the first passage through which the working fluid flows as a result of the movement of the piston, for adjusting the flow of the working fluid moving within the second passage; and a third damping force generating mechanism provided in a third passage arranged in parallel with the first and second passages through which the working fluid flows as a result of the movement of the piston, for adjusting the flow of the working fluid moving within the third passage. The second damping force generating mechanism includes a case member fixed to the piston rod and in which a part of the second passage is formed; a first valve positioned in contact with one axial direction of the case member and adjusting the flow of the working fluid in the second passage; a second valve positioned in contact with the other axial direction of the case member and adjusting the flow of the working fluid in the second passage; and a variable valve provided between the case member and the second valve, which contacts the second valve to form a first variable volume chamber between itself and the second valve, and which opens and closes according to the flow of the working fluid. The first valve is formed by a plurality of valve members and includes a second variable volume chamber whose volume changes according to the pressure in the case member, and a valve mechanism that controls the working fluid in the second variable volume chamber.

[0009] According to this disclosure, it becomes possible to generate damping force more effectively.

[0010] This is a cross-sectional view showing a shock absorber according to the first embodiment of this disclosure. This is a partial cross-sectional view showing the area around the piston of the shock absorber according to the first embodiment of this disclosure. This is a partial cross-sectional view showing a part of plan view showing the seat member of the shock absorber according to the first embodiment of this disclosure. This is a bottom view showing the seat member of the shock absorber according to the first embodiment of this disclosure. This is a hydraulic circuit diagram of the main part of the shock absorber according to the first embodiment of this disclosure. This is a partial cross-sectional view showing a part of the area around the piston of the shock absorber according to the second embodiment of this disclosure. This is a hydraulic circuit diagram of the main part of the shock absorber according to the second embodiment of this disclosure.

[0011] [First Embodiment] The first embodiment of the present disclosure will be described with reference to Figures 1 to 7. For the sake of convenience in the following description, the upper side in Figures 1 to 3 and Figure 8 will be referred to as "upper," and the lower side in Figures 1 to 3 and Figure 8 will be referred to as "lower."

[0012] The shock absorber 1 of the first embodiment is a so-called twin-cylinder type hydraulic shock absorber, as shown in Figure 1. The shock absorber 1 includes a cylinder 2 in which an oil liquid L and a gas G are sealed as working fluids. The cylinder 2 has a cylindrical inner cylinder 3 and a bottomed cylindrical outer cylinder 4. The outer cylinder 4 has a larger diameter than the inner cylinder 3 and is provided concentrically with the inner cylinder 3 so as to cover the inner cylinder 3 on its radially outer side. The space between the inner cylinder 3 and the outer cylinder 4 is a reservoir chamber 6. The cylinder 2 has the oil liquid L sealed inside the inner cylinder 3, and the oil liquid L and gas G sealed in the reservoir chamber 6.

[0013] The outer cylinder 4 has a cylindrical body portion 11 and a cylinder bottom portion 12 that closes the lower part of the body portion 11. An attachment eye 13 is fixed to the cylinder bottom portion 12 on the side opposite to the body portion 11.

[0014] The shock absorber 1 includes a piston 18 that is movably fitted inside the inner cylinder 3 of the cylinder 2. This piston 18 divides the inside of the inner cylinder 3 into two chambers: an upper chamber 19 (first chamber) and a lower chamber 20 (second chamber).

[0015] The shock absorber 1 includes a piston rod 21, one end of which is positioned inside the inner cylinder 3 of the cylinder 2 and connected to the piston 18, and the other end of which extends outside the cylinder 2. The piston 18 and the piston rod 21 move together. In the extension stroke of the shock absorber 1, when the piston rod 21 increases the amount it protrudes from the cylinder 2, the piston 18 moves toward the upper chamber 19. In the contraction stroke of the shock absorber 1, when the piston rod 21 decreases the amount it protrudes from the cylinder 2, the piston 18 moves toward the lower chamber 20.

[0016] Rod guides 22 are fitted to the upper openings of the inner cylinder 3 and the outer cylinder 4. A sealing member 23 is fitted to the outer cylinder 4 above the rod guides 22, on the outer side of the cylinder 2. Both the rod guides 22 and the sealing member 23 are annular in shape. The piston rod 21 is slidably inserted inside the rod guides 22 and the sealing member 23, respectively, and extends from the inside to the outside of the cylinder 2.

[0017] The rod guide 22 supports the piston rod 21 so that it can move axially while restricting its radial movement, and guides the movement of the piston rod 21. The sealing member 23 is in close contact with the outer cylinder 4 at its outer circumference and slides against the outer circumference of the axially moving piston rod 21 at its inner circumference, preventing the oil liquid L in the inner cylinder 3 and the high-pressure gas G and oil liquid L in the reservoir chamber 6 from leaking to the outside.

[0018] The rod guide 22 has a stepped outer circumference, with the upper part being larger in diameter than the lower part. The rod guide 22 fits into the inner circumference of the upper end of the inner cylinder 3 at its smaller diameter lower section, and into the inner circumference of the upper part of the outer cylinder 4 at its larger diameter upper section. A base valve 25 is installed on the cylinder bottom 12 of the outer cylinder 4, defining the lower chamber 20 and the reservoir chamber 6. The inner circumference of the lower end of the inner cylinder 3 is fitted into this base valve 25. The upper end of the outer cylinder 4 is crimped radially inward, and this crimped portion and the rod guide 22 sandwich the sealing member 23.

[0019] The piston rod 21 has a main shaft portion 27 and a mounting shaft portion 28 with a smaller diameter. The mounting shaft portion 28 is positioned inside the cylinder 2 and the piston 18 and the like are attached to it. The end of the main shaft portion 27 on the mounting shaft portion 28 side is a shaft step portion 29 that widens in a direction perpendicular to the axis. A groove 26 extending in the axial direction is formed on the outer circumference of the mounting shaft portion 28 at an intermediate position in the axial direction. The groove 26 forms an intermediate chamber 30 in the piston rod 21. A male thread 31 is formed on the outer circumference of the mounting shaft portion 28 on the side opposite to the main shaft portion 27 from the axial groove 26.

[0020] In the shock absorber 1, for example, the portion of the piston rod 21 protruding from the cylinder 2 is positioned at the top and supported by the vehicle body, while the mounting eye 13 on the cylinder 2 side is positioned at the bottom and connected to the wheel side. If the shock absorber is of the single-tube type, the opposite may be true: the cylinder 2 side may be supported by the vehicle body and the piston rod 21 may be connected to the wheel side. When the wheel vibrates as it moves, the relative positions of the cylinder 2 and the piston rod 21 change with the vibration, but this change is suppressed by the fluid resistance of the flow path formed in at least one of the piston 18 and the piston rod 21. As will be described in detail below, the fluid resistance of the flow path formed in at least one of the piston 18 and the piston rod 21 is made to differ depending on the speed and amplitude of the vibration, and by suppressing the vibration, the ride comfort is improved. In addition to the vibration generated by the wheel, inertial force and centrifugal force generated in the vehicle body as the vehicle moves also act between the cylinder 2 and the piston rod 21. For example, when the direction of travel changes due to steering, centrifugal force is generated in the vehicle body, and a force based on this centrifugal force acts between the cylinder 2 and the piston rod 21. As will be explained below, the shock absorber 1 has good characteristics against vibrations caused by forces generated in the vehicle body as the vehicle moves, and high stability is obtained during vehicle operation.

[0021] As shown in Figure 2, the piston 18 is composed of a metal piston body 35 supported by the mounting shaft portion 28 of the piston rod 21, and an annular synthetic resin sliding member 36 integrally mounted on the outer circumferential surface of the piston body 35. The piston body 35 consists of two disc-shaped piston components 32 and piston components 33. The piston components 32 and 33 are connected by engaging portions 34 with interlocking grooves and protrusions formed on their mating surfaces, aligning their circumferential phases, and in this state the sliding member 36 is mounted on the outer circumferential side. As a result, the piston components 32, 33, and sliding member 36 are integrated to form the piston 18. The piston 18 slides inside the inner cylinder 3 while the sliding member 36 contacts the inner cylinder 3. In the piston 18, the piston component 32 is positioned on the upper chamber 19 side, and the piston component 33 is positioned on the lower chamber 20 side.

[0022] The piston body 35 is provided with a piston passage section 37 that connects the upper chamber 19 and the lower chamber 20, and a piston passage section 39 that connects the upper chamber 19 and the lower chamber 20 separately from the piston passage section 37. The piston passage section 37 is formed from a plurality of passage holes opening into the upper chamber 19 and an annular passage groove connecting the lower chamber 20 side of these passage holes. The piston passage section 39 is formed from a plurality of passage holes opening into the lower chamber 20 and an annular passage groove connecting the upper chamber 19 side of these passage holes. The passage holes of the piston passage section 37 and the passage holes of the piston passage section 39 are arranged alternately in the circumferential direction of the piston body 35. The piston passage section 37 opens radially outward on the upper chamber 19 side and radially inward on the lower chamber 20 side. The piston passage section 39 opens radially outward on the lower chamber 20 side and radially inward on the upper chamber 19 side.

[0023] A first damping force generating mechanism 40 is provided in the piston passage 37, which generates damping force by opening and closing the piston passage 37. The first damping force generating mechanism 40 is located on the lower chamber 20 side, which is one end of the piston 18 in the axial direction, and is attached to the piston rod 21. Because the first damping force generating mechanism 40 is located on the lower chamber 20 side, the piston passage 37 becomes a passage through which oil L flows from one upper chamber 19 to the other lower chamber 20 during the movement of the piston 18 toward the upper chamber 19 side, i.e., the extension stroke. The first damping force generating mechanism 40 provided in relation to the piston passage 37 is an extension-side damping force generating mechanism that generates damping force by suppressing the flow of oil L in the extension-side piston passage 37.

[0024] A first damping force generating mechanism 42 is provided in the piston passage 39, which generates damping force by opening and closing the piston passage 39. The first damping force generating mechanism 42 is located on the upper chamber 19 side, which is the other axial end of the piston 18, and is attached to the piston rod 21. Because the first damping force generating mechanism 42 is located on the upper chamber 19 side, the piston passage 39 becomes a passage through which oil liquid L flows from one lower chamber 20 to the other upper chamber 19 during the movement of the piston 18 toward the lower chamber 20 side, that is, during the compression stroke. The first damping force generating mechanism 42 provided in relation to the piston passage 39 is a compression-side damping force generating mechanism that generates damping force by suppressing the flow of oil liquid L in the compression-side piston passage 39.

[0025] In the shock absorber 1, the piston passage section 37 and the piston passage section 39 are connected so that the working fluid, oil L, flows between the upper chamber 19 and the lower chamber 20 as the piston 18 moves. The oil L passes through the piston passage section 37 when the piston rod 21 and piston 18 move in the extension direction (upper side in Figure 2). The oil L passes through the piston passage section 39 when the piston rod 21 and piston 18 move in the compression direction (lower side in Figure 2).

[0026] The piston body 35 has a roughly disc shape, and a fitting hole 44 is formed in the center of its radial direction, penetrating axially for fitting the mounting shaft portion 28 of the piston rod 21. The piston body 35 has a groove 45 formed on the end face of the piston component 33 on the piston component 32 side, which opens to the piston passage portion 37 and the fitting hole 44. The groove 45 is an orifice 46. The orifice 46 keeps the piston passage portion 37 in constant communication with the intermediate chamber 30 of the mounting shaft portion 28.

[0027] At the axial end of the piston body 35 on the lower chamber 20 side, an annular valve seat portion 47, which is part of the first damping force generating mechanism 40, is formed radially outward from the opening of the piston passage portion 37 on the lower chamber 20 side. Also, at the axial end of the piston body 35 on the upper chamber 19 side, an annular valve seat portion 49, which is part of the first damping force generating mechanism 42, is formed radially outward from the opening of the piston passage portion 39 on the upper chamber 19 side.

[0028] In the piston body 35, the opening on the lower chamber 20 side of the compression piston passage 39 is located on the opposite side of the fitting hole 44 of the valve seat portion 47. In the piston body 35, the opening on the upper chamber 19 side of the extension piston passage 37 is located on the opposite side of the fitting hole 44 of the valve seat portion 49.

[0029] On the upper chamber 19 side of the piston 18, in order from the axial piston 18 side, one retainer 51, multiple (specifically six) valve discs 52, one retainer 53, multiple (specifically two) retainers 54, and one washer 55 are stacked. The retainers 51, 53, 54, valve discs 52, and washers 55 are all made of metal and are perforated circular flat plates of a certain thickness that can accommodate the mounting shaft portion 28 of the piston rod 21 on the inside. The multiple valve discs 52 are provided to be flexible.

[0030] The retainer 51 has an outer diameter smaller than the inner diameter of the valve seat portion 49 of the piston 18.

[0031] The valve disc 52 closest to the piston 18 has a larger outer diameter than the valve seat portion 49 of the piston 18. This valve disc 52 closest to the piston 18 is in contact with the valve seat portion 49, and opens and closes the opening of the piston passage portion 39 formed in the piston 18 by separating from and contacting the valve seat portion 49. The outer diameter of each of the valve discs 52 is equal to or smaller than the outer diameter of the adjacent valve disc 52 on the piston 18 side.

[0032] The retainer 53 has an outer diameter smaller than the outer diameter of the valve disc 52 that is furthest away from the piston 18.

[0033] The multiple retainers 54 have the same outer diameter, and their outer diameter is larger than that of retainer 53.

[0034] The washer 55 has an outer diameter that is larger than the outer diameter of the retainer 53 and smaller than the outer diameter of the retainer 54. The washer 55 is thicker and more rigid than the multiple valve discs 52. The washer 55 has an outer diameter that is larger than the outer diameter of the shaft step portion 29 of the piston rod 21 and is in contact with the shaft step portion 29.

[0035] Multiple valve discs 52 constitute the piston main valve 58. The piston main valve 58 can seat in and out of the valve seat portion 49, and by seating away from the valve seat portion 49, it opens the piston passage portion 39 to the upper chamber 19. The piston main valve 58 generates a damping force by suppressing the flow of oil L from the lower chamber 20 to the upper chamber 19 caused by the sliding of the piston 18 toward the compression side, i.e., toward the lower chamber 20 side. The piston main valve 58 is provided on the upper chamber 19 side of the cylinder 2. The piston main valve 58 and the valve seat portion 49 constitute the compression side first damping force generating mechanism 42. The piston passage portion 39 and the passage between the piston main valve 58 and the valve seat portion 49 when the valve is open constitute the compression side first passage 60 through which the working fluid, oil L, flows from one lower chamber 20 to the other upper chamber 19 as the piston 18 moves toward the compression side. The first damping force generating mechanism 42 is provided in the first passage 60 and adjusts the flow of the oil liquid L moving within the first passage 60.

[0036] As shown in Figure 3, on the lower chamber 20 side of the piston 18, in order from the axial piston 18 side, one retainer 71, one valve disc 72, multiple (specifically two) valve discs 73, one pilot valve 74, one retainer 75, one retainer 76, multiple (specifically two) retainers 77, one communicating disc 78, one regulating member 79, multiple (specifically two) seat discs 81, one sub-valve 82 (valve member, first valve), one retainer 83, and one pilot case 84 (case member) are stacked.

[0037] Furthermore, on the side of the pilot case 84 opposite to the piston 18, in order from the axial pilot case 84 side, one retainer 91, one variable valve 92 (partition member), one retainer 93, one retainer 94, one retainer 95, one valve disc 96, one valve disc 97, multiple (specifically eight) valve discs 98, one retainer 99, and one retainer 100 are stacked on top of each other.

[0038] The retainers 71, 75-77, 83, 91, 93-95, 99, 100, valve discs 72, 73, 96, 97, 98, communication disc 78, regulating member 79, seat disc 81, sub-valve 82, pilot case 84, and variable valve 92 are all made of metal. The retainers 71, 75-77, 83, 91, 93-95, 99, 100, valve discs 72, 73, 96, 97, 98, and communication disc 78 are all perforated flat plates of a certain thickness that can accommodate the mounting shaft portion 28 of the piston rod 21 on the inside. The sub-valve 82 is a perforated flat plate of a certain thickness that can accommodate the mounting shaft portion 28 of the piston rod 21 on the inside. The valve discs 72, 73, 96, 97, 98, and sub-valve 82 are provided to be flexible. The pilot valve 74, regulating member 79, pilot case 84, and variable valve 92 all have annular shapes on their insides, allowing the mounting shaft portion 28 of the piston rod 21 to be fitted.

[0039] The retainer 71 has an outer diameter smaller than the inner diameter of the valve seat portion 47 of the piston 18. The valve disc 72 has an outer diameter equal to the outer diameter of the valve seat portion 47 of the piston 18. The valve disc 72 is in contact with the valve seat portion 47 and opens and closes the opening of the piston passage portion 37 formed in the piston 18 by separating from and contacting the valve seat portion 47. The valve disc 72 has a notch 131 formed on the outer peripheral edge of the radial outer circumference that penetrates axially, extends radially, and exits radially outward. Multiple notches 131 are formed on the valve disc 72 at equal intervals in the circumferential direction of the valve disc 72. The passages within these notches 131 serve as fixed orifices 132 that connect the piston passage portion 37 to the lower chamber 20 even when the valve disc 72 is in contact with the valve seat portion 47. Multiple valve discs 73 have the same outer diameter and are also equal in outer diameter to the valve disc 72.

[0040] The pilot valve 74 consists of a metal disc 135 and a rubber sealing member 136 fixed to the outer circumference of the disc 135. The disc 135 is a perforated circular flat plate of a certain thickness, into which the mounting shaft portion 28 of the piston rod 21 can be fitted, and is flexible. The outer diameter of the disc 135 is larger than the outer diameter of the valve disc 73. The sealing member 136 is fixed to the outer circumference of the side of the disc 135 opposite to the piston 18, and is an annular shape coaxial with the disc 135.

[0041] The valve discs 72, 73 and the pilot valve 74 constitute the piston main valve 138. The piston main valve 138 can seat and disseat from the valve seat portion 47, and by disseat from the valve seat portion 47, it opens the piston passage portion 37 to the lower chamber 20. The piston main valve 138 generates a damping force by suppressing the flow of oil L from the upper chamber 19 to the lower chamber 20 caused by the sliding of the piston 18 toward the extension side, i.e., toward the upper chamber 19 side. The piston main valve 138 is provided on the lower chamber 20 side of the cylinder 2. The piston main valve 138 and the valve seat portion 47 constitute the extension side first damping force generating mechanism 40. The piston passage portion 37 and the passage between the piston main valve 138 and the valve seat portion 47 when the valve is open constitute the extension side first passage 140 through which the working fluid, oil L, flows from one upper chamber 19 to the other lower chamber 20 as the piston 18 moves toward the extension side. The first damping force generating mechanism 40 is provided in the first passage 140 and adjusts the flow of the oil liquid L moving within the first passage 140.

[0042] The outer diameter of retainer 75 is smaller than the inner diameter of the sealing member 136 of the pilot valve 74. The outer diameter of retainer 76 is larger than the outer diameter of retainer 75, but smaller than the inner diameter of the sealing member 136 of the pilot valve 74. Retainer 76 is thicker and more rigid than the disc 135 of the pilot valve 74. Multiple retainers 77 have the same outer diameter, which is smaller than the outer diameter of retainer 76 and larger than the outer diameter of retainer 75.

[0043] The communication disk 78 has an outer diameter larger than that of the retainer 77. The communication disk 78 is formed with a notch 141 extending radially outward from an inner peripheral edge fitted to the mounting shaft portion 28 of the piston rod 21 to a position outside the retainer 77. A plurality of notches 141 are formed in the communication disk 78 at equal intervals in the circumferential direction of the communication disk 78. The passages within these notches 141 form communication orifices 142 that are always in communication with the intermediate chamber 30 of the piston rod 21.

[0044] The restricting member 79 includes a perforated disk-shaped main body portion 145 and a protruding portion 146 protruding from the inner peripheral side of the main body portion 145 to one side in the axial direction of the main body portion 145. The outer diameter of the protruding portion 146 is equal to the outer diameter of the retainer 77. The outer diameter of the main body portion 145 is larger than the outer diameter of the communication disk 78. The restricting member 79 abuts against the communication disk 78 at the protruding portion 146. The plurality of sheet disks 81 have the same outer diameter, which is smaller than the outer diameter of the main body portion 145 of the restricting member 79 and larger than the outer diameter of the protruding portion 146 of the restricting member 79. The outer diameter of the retainer 83 is smaller than the outer diameter of the sheet disk 81.

[0045] The pilot case 84 is integrally formed without seams. The pilot case 84 includes a bottom portion 151, a valve seat portion 152, and an outer cylindrical portion 153. The bottom portion 151 is in the shape of a perforated disk. The valve seat portion 152 is annular and protrudes from the outer peripheral side of the bottom portion 151 to one side along the axial direction of the bottom portion 151. The outer cylindrical portion 153 is cylindrical, and protrudes from the outer peripheral edge portion radially outside the valve seat portion 152 of the bottom portion 151 to the same side as the valve seat portion 152 along the axial direction of the bottom portion 151, and protrudes more than the valve seat portion 152. The outer cylindrical portion 153 is open at the side opposite to the bottom portion 151 in the axial direction.

[0046] The pilot case 84 has an inner seat portion 155 and a valve seat portion 156. The inner seat portion 155 is annular and protrudes from the inner circumference of the bottom portion 151 along the axial direction of the bottom portion 151 on the side opposite to the outer cylindrical portion 153. The valve seat portion 156 is annular and protrudes from the outer peripheral edge of the bottom portion 151 radially outward from the inner seat portion 155, along the axial direction of the bottom portion 151 on the same side as the inner seat portion 155 and more than the inner seat portion 155. The bottom portion 151, valve seat portion 152, outer cylindrical portion 153, inner seat portion 155 and valve seat portion 156 are formed coaxially.

[0047] The pilot case 84 has an outer cylindrical portion 153 that protrudes from the bottom portion 151 toward the piston 18, and the bottom portion 151 abuts against the retainer 83. The outer cylindrical portion 153 is fitted with the sealing member 136 of the pilot valve 74 inside. The sealing member 136 moves axially while maintaining close contact with the inner circumferential surface of the outer cylindrical portion 153 in accordance with the deflection of the disc 135 of the pilot valve 74. The outer cylindrical portion 153 of the pilot case 84 and the sealing member 136 of the pilot valve 74 cover the retainers 75-77, 83, the communicating disc 78, the regulating member 79, the seat disc 81, and the sub-valve 82 radially outward.

[0048] In the bottom portion 151 of the pilot case 84, an axially penetrating passage hole 161 is formed between the valve seat portions 152, 156, the outer cylindrical portion 153, and the inner seat portion 155. A plurality of said passage holes 161 are formed in the bottom portion 151 at equal intervals in the circumferential direction thereof. The pilot case 84 has, between two circumferentially adjacent passage holes 161 on the bottom portion 151, a protrusion 162 protruding from the bottom portion 151 toward the valve seat portion 152 along the axial direction of the bottom portion 151, the protrusion being lower than the valve seat portion 152. The pilot case 84 has a plurality of protrusions 162 arranged at intervals in the circumferential direction of the bottom portion 151. A plurality of said protrusions 162 are respectively arranged at all positions between two circumferentially adjacent passage holes 161 on the bottom portion 151. On the inner circumference of the pilot case 84, a fitting hole 163 for fitting the mounting shaft portion 28 of the piston rod 21 is formed axially penetrating through the bottom portion 151 and the inner seat portion 155.

[0049] In the pilot case 84, the side of the bottom portion 151 opposite to the inner seat portion 155 in the axial direction abuts against the retainer 83. At this time, for the bottom portion 151, the radially inner portion of the bottom portion 151 relative to the plurality of passage holes 161 and the plurality of protrusions 162 abuts against the retainer 83.

[0050] The outer diameter of the sub-valve 82 is smaller than the inner diameter of the outer cylindrical portion 153 of the pilot case 84 and larger than the outer diameter of the valve seat portion 152 of the pilot case 84. The inner diameter of the sub-valve 82 is smaller than the outer diameter of the seat disc 81 and larger than the outer diameter of the retainer 83. In the sub-valve 82, the annular outer peripheral valve portion 166 on the outer peripheral side abuts against the valve seat portion 152 of the pilot case 84, and the annular inner peripheral valve portion 167 on the inner peripheral side abuts against the seat disc 81. The sub-valve 82 is in a flat plate shape before being assembled; when assembled and abutted against the valve seat portion 152 and the seat disc 81, it is elastically deformed into a substantially tapered shape in the axial direction such that the outer peripheral valve portion 166 is located closer to the piston 18 than the inner peripheral valve portion 167. Thereby, the sub-valve 82 is pressed against the valve seat portion 152 and the seat disc 81. The main body portion 145 of the aforementioned restricting member 79 is thicker and has higher rigidity than the sub-valve 82.

[0051] The portion enclosed by the outer cylindrical portion 153 and valve seat portion 152 of the pilot case 84, the pilot valve 74, retainers 75-77, the communicating disc 78, the regulating member 79, the seat disc 81, and the sub-valve 82 forms the back pressure chamber 170. The back pressure chamber 170 communicates with the upper chamber 19 via the communicating orifice 142 of the communicating disc 78, the intermediate chamber 30 of the piston rod 21, and the orifice 46 and piston passage portion 37 of the piston 18 shown in Figure 2. The back pressure chamber 170 shown in Figure 3 applies the pressure from the upper chamber 19, introduced via the communicating orifice 142, to the pilot valve 74, i.e., the piston main valve 138, in the direction of the piston 18, i.e., in the valve closing direction.

[0052] The retainer 91 has an outer diameter smaller than the outer diameter of the inner seat portion 155 of the pilot case 84. The variable valve 92 has a disc spring shape and has a radially inner base portion 175 and a radially outer tapered plate portion 176. The base portion 175 is a perforated flat plate of a certain thickness that can accommodate the mounting shaft portion 28 of the piston rod 21 on its inner side. The tapered plate portion 176 widens radially outward from the outer peripheral edge of the base portion 175 and has a tapered cylindrical shape that moves further axially away from the base portion 175 the radially outward. The variable valve 92 has an outer diameter of the base portion 175 that is larger than the outer diameter of the retainer 91, and an outer diameter of the tapered plate portion 176 that is smaller than the inner diameter of the valve seat portion 156 of the pilot case 84. In the axial direction, the variable valve 92 is oriented such that the tapered plate portion 176 is positioned opposite to the bottom portion 151 of the pilot case 84 relative to the base portion 175.

[0053] The outer diameter of retainer 93 is smaller than the outer diameter of the base portion 175 of the variable valve 92 and is the same as the outer diameter of retainer 91. The outer diameter of retainer 94 is larger than the outer diameter of retainer 93 and smaller than the outer diameter of the base portion 175 of the variable valve 92.

[0054] The retainer 95 has an outer diameter that is larger than the outer diameter of the retainer 94, larger than the outer diameter of the base portion 175 of the variable valve 92, and smaller than the outer diameter of the tapered plate portion 176 of the variable valve 92. The retainer 95 has a notch 181 formed on the outer peripheral edge of its radial circumference, which penetrates in the thickness direction, extends radially, and exits radially outward. Multiple notches 181 are formed on the retainer 95 at equal intervals in the circumferential direction of the retainer 95. The inner end position of the notch 181 in the radial direction of the retainer 95 coincides with the outer end position in the radial direction of the retainer 94. The retainer 95 has at least three notches 181 formed therein. The variable valve 92 is provided spaced apart from the retainers 93 to 95 such that the tapered plate portion 176 on the outer circumference covers the outer circumference of the retainers 93 to 95, with the outer diameter increasing as it moves away from the base portion 175.

[0055] The valve disc 96 has an outer diameter equivalent to the outer diameter of the valve seat portion 156 of the pilot case 84. The valve disc 96 is able to be separated from and in contact with the valve seat portion 156. The valve disc 96 has a passage hole 185 that penetrates it in the axial direction. The passage hole 185 is in the shape of an arc extending in the circumferential direction of the valve disc 96. The passage hole 185 is located outside the outer peripheral edge of the retainer 95 and inside the outer peripheral edge of the tapered plate portion 176 of the variable valve 92. The portion of the valve disc 96 that is radially outside the passage hole 185 comes into contact with the outer peripheral edge of the tapered plate portion 176 of the variable valve 92 over its entire circumference. At that time, the variable valve 92 presses against the valve disc 96 over its entire circumference because the tapered plate portion 176 undergoes elastic deformation.

[0056] The portion enclosed by the sub-valve 82, the valve seat portion 152 and bottom portion 151 of the pilot case 84, the seat disc 81, and the retainer 83, the portion enclosed by the valve seat portion 156, bottom portion 151, and inner seat portion 155 of the pilot case 84, the retainer 91, the variable valve 92, and the valve disc 96, and the passages within the multiple passage holes 161 of the pilot case 84 constitute the variable volume chamber 191. Furthermore, the portion enclosed by the variable valve 92, the retainers 93 to 95, and the valve disc 96 constitutes the variable volume chamber 192 (first variable volume chamber).

[0057] When the pressure in the back pressure chamber 170 of the sub-valve 82 becomes higher than the pressure in the variable volume chamber 191, the inner circumferential valve portion 167 of the sub-valve 82 separates from the seat disc 81, allowing the oil L from the back pressure chamber 170 to flow into the variable volume chamber 191. The inner circumferential valve portion 167 of the sub-valve 82 and the seat disc 81 constitute a sub-valve mechanism 201 that controls the communication and blocking of the back pressure chamber 170 and the variable volume chamber 191 by opening and closing. The sub-valve mechanism 201 generates a damping force when it opens to allow the oil L from the back pressure chamber 170 to flow into the variable volume chamber 191. Multiple protrusions 162 of the pilot case 84 limit the amount of opening by contacting the portion of the sub-valve 82 on the inner circumferential valve portion 167 side when the sub-valve mechanism 201 is opened. Furthermore, the multiple protrusions 162 suppress contact between the inner circumferential valve portion 167 side of the sub-valve 82 and the bottom 151 when the sub-valve mechanism 201 is opened, thereby preventing the inner circumferential valve portion 167 side of the sub-valve 82 from sticking to the bottom 151.

[0058] When the pressure on the volume variable chamber 191 side of the sub-valve 82 becomes higher than the pressure in the back pressure chamber 170, the outer peripheral valve portion 166 of the sub-valve 82 separates from the valve seat portion 152 of the pilot case 84, allowing the oil L from the volume variable chamber 191 to flow into the back pressure chamber 170. The outer peripheral valve portion 166 and the valve seat portion 152 of the sub-valve 82 open and close to form a sub-valve mechanism 202 that controls the communication and blocking of the volume variable chamber 191 and the back pressure chamber 170. The sub-valve mechanism 202 generates a damping force when it opens to allow the oil L from the volume variable chamber 191 side to flow into the back pressure chamber 170. The main body portion 145 of the regulating member 79 abuts against the portion of the sub-valve 82 on the outer peripheral valve portion 166 side when the sub-valve mechanism 202 opens, thereby suppressing further deformation of the sub-valve 82 and limiting the amount of opening. The sub-valve 82 is annular in shape and has an outer circumferential valve portion 166 that allows one flow of the oil liquid L and an inner circumferential valve portion 167 that allows the other flow of the oil liquid L.

[0059] The volume of the variable volume chambers 191 and 192 changes when the variable valve 92 deforms. When the pressure in the variable volume chamber 191 becomes higher than the pressure in the variable volume chamber 192, the variable valve 92 elastically deforms to move closer to the valve disc 96, increasing the volume of the variable volume chamber 191 while decreasing the volume of the variable volume chamber 192. When the pressure in the variable volume chamber 192 becomes higher than the pressure in the variable volume chamber 191, the variable valve 92 elastically deforms to move away from the valve disc 96, increasing the volume of the variable volume chamber 192 while decreasing the volume of the variable volume chamber 191. The pilot case 84, sub-valve 82, seat disc 81, retainer 83, retainer 91, variable valve 92, retainers 93-95 and valve disc 96, which form the variable volume chambers 191 and 192, together constitute a variable damping force mechanism 193 that varies the damping force according to the piston frequency, which is the frequency of the axial movement of the piston 18.

[0060] Here, when the pressure in the variable volume chamber 191 becomes higher than the pressure in the variable volume chamber 192 by a predetermined value or more, the variable valve 92 undergoes a large elastic deformation to approach the valve disc 96 and comes into contact with the outer peripheral edge of the retainer 95 at the tapered plate portion 176. As a result, the variable volume chamber 192 is divided into a first volume chamber 194 located radially inward from the portion of the variable valve 92 that contacts the retainer 95, and a second volume chamber 195 located radially outward from the portion of the variable valve 92 that contacts the retainer 95. In this state, the first volume chamber 194 and the second volume chamber 195 are in communication through a passage in the notch 181 formed on the outer peripheral edge of the retainer 95.

[0061] The valve disc 97 has an outer diameter equal to that of the valve disc 96. The valve disc 97 has a notch 197 formed on its radially outward side that penetrates axially and exits radially outward. The passage within the notch 197 is in constant communication with the passage within the passage hole 185 of the valve disc 96. The passage within the notch 197 and the passage within the passage hole 185 of the valve disc 96 connect the variable volume chamber 192 and the lower chamber 20.

[0062] When the pressure in the variable-volume chamber 192 becomes higher than the pressure in the variable-volume chamber 191 by a predetermined value or more, the variable valve 92 elastically deforms so as to move away from the valve disc 96, and the outer peripheral edge of the tapered plate portion 176 separates from the valve disc 96. Then, the variable-volume chamber 192 communicates with the variable-volume chamber 191, and the oil liquid L flows from the variable-volume chamber 192 to the variable-volume chamber 191. The outer peripheral edge of the tapered plate portion 176 of the variable valve 92 and the valve disc 96 open and close to form a valve mechanism 205 that controls the communication and blockage between the variable-volume chamber 192 and the variable-volume chamber 191. The valve mechanism 205 allows the flow of oil liquid L from the variable-volume chamber 192 to the variable-volume chamber 191 and generates a damping force when it opens to allow the oil liquid L to flow from the variable-volume chamber 192 to the variable-volume chamber 191.

[0063] The back pressure chamber 170 in the pilot case 84, due to the pressure from the upper chamber 19 introduced through the communicating orifice 142, opens the sub-valve mechanism 201, deforming the variable valve 92 in such a way that it increases the volume of the variable volume chamber 191 and decreases the volume of the variable volume chamber 192.

[0064] The valve disc 98 closest to the pilot case 84 has an outer diameter equivalent to that of valve disc 97. The outer diameter of each valve disc 98 is equivalent to or smaller than that of an adjacent valve disc 98 on the pilot case 84 side.

[0065] The outer diameter of the retainer 99 is smaller than that of the valve disc 98 that is furthest away from the pilot case 84. The outer diameter of the retainer 100 is larger than that of the retainer 99.

[0066] Multiple valve discs 96 to 98 constitute a hard valve 211 (partition member, second valve). The hard valve 211 is repositionable on and off the valve seat portion 156, and by repositioning from the valve seat portion 156, it connects the variable volume chamber 191 to the lower chamber 20. The hard valve 211 generates a damping force by allowing and suppressing the flow of oil liquid L from the upper chamber 19, which is created by the sliding of the piston 18 toward the extension side, i.e., toward the upper chamber 19, to the lower chamber 20 via the piston passage portion 37 and orifice 46 of the piston 18, the intermediate chamber 30 of the piston rod 21, the communication orifice 142 of the communication disc 78, the back pressure chamber 170, the passage between the inner circumferential valve portion 167 of the sub-valve 82 and the seat disc 81, which is created when the sub-valve mechanism 201 is opened, and the variable volume chamber 191 when the valve is opened. The hard valve 211 is provided on the lower chamber 20 side of the cylinder 2. The hard valve 211 and the valve seat portion 156 of the pilot case 84 constitute the extension-side hard valve mechanism 212. The hard valve 211 is positioned to be in contact with the valve seat portion 156 of the pilot case 84 and opens away from the valve seat portion 156. A sub-valve 82 is provided on one axial side of the pilot case 84, and the hard valve 211 is provided on the other axial side of the pilot case 84. A variable valve 92 and retainers 93-95 are provided between the pilot case 84 and the hard valve 211.

[0067] The piston passage 37 and orifice 46 of the piston 18, the intermediate chamber 30 of the piston rod 21, the communication orifice 142 of the communication disk 78, the back pressure chamber 170, the passage between the inner circumferential valve portion 167 of the sub-valve 82 and the seat disk 81 that is created when the sub-valve mechanism 201 opens, the variable volume chamber 191, and the passage between the hard valve 211 and the valve seat portion 156 that is created when the hard valve mechanism 212 opens, all constitute the extension-side second passage 215 through which the working fluid, oil liquid L, flows from one upper chamber 19 to the other lower chamber 20 as the piston 18 moves toward the extension side. The hard valve 211 operates to allow one-way flow of oil liquid L from the upper chamber 19 to the lower chamber 20 through the second passage 215. The variable volume chamber 192, the passage in the passage hole 185 of the valve disk 96, and the passage in the notch 197 of the valve disk 97 also constitute the second passage 215. The second passage 215 runs parallel to the first passage 140, which is also on the extension side, except for a portion on the upper chamber 19 side of the orifice 46 of the piston passage 37, and connects the upper chamber 19 and the lower chamber 20. The sub-valve mechanism 201 restricts the flow of oil L from the upper chamber 19 to the lower chamber 20 through the second passage 215 when the piston 18 starts to move in the extension stroke.

[0068] The second passage 215 is provided with an orifice 46, a communication orifice 142, a back pressure chamber 170, a sub-valve mechanism 201, a damping force variable mechanism 193, and a hard valve mechanism 212. The sub-valve mechanism 201, the damping force variable mechanism 193, and the hard valve mechanism 212 are positioned in the second passage 215 so that the flow of the oil liquid L is in series, and constitute a second damping force generating mechanism 216 that adjusts the flow of the oil liquid L moving within the second passage 215.

[0069] The passage in the notch 197 of the valve disc 97, the passage in the passage hole 185 of the valve disc 96, the variable volume chamber 192, the passage between the variable valve 92 and the valve disc 96 that is created when the valve mechanism 205 is opened, the variable volume chamber 191, the passage between the outer peripheral valve portion 166 and the valve seat portion 152 of the sub-valve 82 that is created when the sub-valve mechanism 202 is opened, the back pressure chamber 170, the communication orifice 142 of the communication disc 78, the intermediate chamber 30 of the piston rod 21, and the orifice 46 and piston passage portion 37 of the piston 18 constitute the second passage 220 on the compression side, through which the working fluid, oil liquid L, flows from one lower chamber 20 to the other upper chamber 19 as the piston 18 moves toward the compression side. The second passage 220 is parallel to the first passage 60 on the compression side and connects the lower chamber 20 and the upper chamber 19. The second passage 220 is provided with a damping force variable mechanism 193, a sub-valve mechanism 202, a back pressure chamber 170, a communication orifice 142, and an orifice 46. The second damping force generating mechanism 216 is configured such that the damping force variable mechanism 193 and the sub-valve mechanism 202 are positioned in the second passage 220 so that the flow of the oil liquid L is in series, thereby adjusting the flow of the oil liquid L in the second passage 220.

[0070] The second damping force generating mechanism 216 includes a main body portion 145 of a restricting member 79 that restricts the amount of opening when the outer peripheral valve portion 166 of the sub-valve 82 of the sub-valve mechanism 202 opens, and a protruding portion 162 of a pilot case 84 that restricts the amount of opening when the inner peripheral valve portion 167 opens. The sub-valve mechanism 202 restricts the flow of oil liquid L from the lower chamber 20 to the upper chamber 19 via the second passage 220 when the piston 18 starts moving in the compression stroke.

[0071] As shown in Figure 4, on the side of the retainer 100 opposite to the retainer 99 in the axial direction, a spring member 401, a retainer 402, a valve member 403 (third valve), and a seat member 406 with an O-ring 405 on its outer circumference are stacked in that order from the retainer 100 side. On the side of the seat member 406 opposite to the valve member 403 in the axial direction, a valve member 407 (third valve), multiple retainers 408 (specifically two), a spring member 409, a retainer 410, multiple retainers 412 (specifically three), a case member 418, a retainer 421, and a washer 422 are stacked in that order from the seat member 406 side.

[0072] The retainers 402, 408, 410, 412, and 421, the spring members 401 and 409, the valve members 403 and 407, the seat member 406, the case member 418, and the washer 422 are all made of metal. The retainers 402, 408, 410, 412, and 421, the valve members 403 and 407, and the washer 422 are all perforated circular flat plates of a certain thickness that can accommodate the mounting shaft portion 28 of the piston rod 21 on the inside. The spring members 401 and 409, the seat member 406, and the case member 418 are all annular in shape that can accommodate the mounting shaft portion 28 of the piston rod 21 on the inside. The spring members 401 and 409 and the valve members 403 and 407 are provided to be flexible.

[0073] The components from washer 55 to washer 422 shown in Figure 2, including the pilot case 84, are installed with the mounting shaft portion 28 of the piston rod 21 inserted through the inside. A nut 105 is screwed onto a male thread 31 provided on the portion of the mounting shaft portion 28 that protrudes from washer 422 and tightened. As a result, the components from washer 55 to washer 422, including the pilot case 84, are clamped to the piston rod 21 by the shaft step portion 29 and the nut 105, at least on their inner circumference, except for the sub-valve 82, and are fixed to the piston rod 21.

[0074] As shown in Figure 4, the case member 418 is a bottomed cylindrical integrally molded product. The case member 418 has a bottom portion 431, an intermediate tapered portion 432, and a cylindrical portion 433. The bottom portion 431 is a perforated disc-shaped plate. The intermediate tapered portion 432 extends from the outer peripheral edge of the bottom portion 431 in one axial direction of the bottom portion 431, expanding in diameter. The intermediate tapered portion 432 is annular.

[0075] The cylindrical portion 433 extends in the axial direction of the intermediate tapered portion 432 from the edge opposite to the bottom portion 431 of the intermediate tapered portion 432, and in the direction opposite to the bottom portion 431. The cylindrical portion 433 is cylindrical in shape.

[0076] The mounting shaft portion 28 of the piston rod 21 is fitted into the inner circumference of the bottom portion 431 of the case member 418. The case member 418 is oriented such that the bottom portion 431 is located on the opposite side from the retainer 99 than the cylindrical portion 433 in its axial direction. The bottom portion 431 of the case member 418 abuts against the retainer 421. The outer diameter of the retainer 421 is smaller than the outer diameter of the bottom portion 431. The outer diameter of the washer 422 is smaller than the outer diameter of the retainer 421.

[0077] A seat member 406, a valve member 407, retainers 408, 410, and 412, and a spring member 409 are arranged radially inside the case member 418. Multiple retainers 412 have the same outer diameter. The outer diameter of each retainer 412 is smaller than the outer diameter of the bottom 431 of the case member 418. The outer diameter of retainer 410 is larger than the outer diameter of retainer 412 and also larger than the outer diameter of the bottom 431 of the case member 418.

[0078] The spring member 409 is flexible. The spring member 409 has a base plate portion 441 and a plurality of spring plate portions 442. The base plate portion 441 is a perforated circular flat plate. The mounting shaft portion 28 is fitted into the inner circumference of the base plate portion 441.

[0079] Multiple spring plate portions 442 extend radially from the outer peripheral edge of the base plate portion 441. The further outward the multiple spring plate portions 442 are from the base plate portion 441 in the axial direction, the further they are from the base plate portion 441 in the radial direction. The spring member 409 contacts the retainer 410 on the base plate portion 441. The further outward the multiple spring plate portions 442 are from the retainer 410 in the axial direction, the further they are from the base plate portion 441 in the radial direction.

[0080] Multiple retainers 408 have the same outer diameter. The outer diameter of the retainer 408 is smaller than the outer diameter of the base portion 441 of the spring member 409. The retainer 408 abuts against the base portion 441 of the spring member 409.

[0081] The valve member 407 is flexible. The outer diameter of the valve member 407 is larger than the maximum outer diameter of the spring member 409. The outer circumference portion of the valve member 407 abuts against multiple spring plate portions 442 of the spring member 409.

[0082] As shown in Figures 5 and 6, the sheet member 406 is a perforated disc shape. The sheet member 406 has a central hole 451 that penetrates through its radial center in the axial direction. As shown in Figure 4, the mounting shaft portion 28 of the piston rod 21 is inserted through the central hole 451 of the sheet member 406.

[0083] As shown in Figures 5 and 6, the central hole 451 has a first inner circumferential wall 452 and a second inner circumferential wall 453. The inner surface of the first inner circumferential wall 452 is cylindrical. As shown in Figure 4, the first inner circumferential wall 452 penetrates the sheet member 406 in the axial direction.

[0084] As shown in Figures 5 and 6, the second inner circumferential wall 453 is recessed radially outward from the inner surface of the first inner circumferential wall 452. The inner surface of the second inner circumferential wall 453 is semi-cylindrical. As shown in Figure 4, the second inner circumferential wall 453 extends linearly along the axial direction of the sheet member 406 and penetrates the sheet member 406 in the axial direction. As shown in Figures 5 and 6, the central hole 451 has multiple (specifically three) second inner circumferential walls 453 at equal intervals in the circumferential direction of the first inner circumferential wall 452.

[0085] The central hole 451 has an insertion hole 454 on the inside of the first inner circumferential wall 452 through which the mounting shaft portion 28 of the piston rod 21 is inserted, as shown in Figure 4, and an expansion portion 455 on the inside of the second inner circumferential wall 453 that expands radially outward from the insertion hole 454. The sheet member 406 has multiple (specifically three) expansion portions 455 at equal intervals in the circumferential direction of the insertion hole 454. As shown in Figure 4, both the insertion hole 454 and the expansion portions 455 extend from one end face to the other end face in the axial direction of the sheet member 406 and penetrate the sheet member 406.

[0086] The mounting shaft portion 28 of the piston rod 21 fits into the first inner circumferential wall 452 of the central hole 451. As a result, the second inner circumferential wall 453 is spaced radially apart from the mounting shaft portion 28 of the piston rod 21. The central hole 451, together with the groove 26 of the piston rod 21, forms an intermediate chamber 30 within the second inner circumferential wall 453.

[0087] As shown in Figure 4, the seat member 406 has an inner seat portion 461 and a valve seat portion 462 at one end on the axial side. As shown in Figure 5, the inner seat portion 461 is annular in shape, surrounding the central hole 451. The valve seat portion 462 extends radially outward from the inner seat portion 461.

[0088] As shown in Figure 4, the seat member 406 has an inner seat portion 464 and a valve seat portion 465 at the other end on the axial side. As shown in Figure 6, the inner seat portion 464 is annular in shape, surrounding the central hole 451. The valve seat portion 465 extends radially outward from the inner seat portion 464.

[0089] As shown in Figure 4, the seat member 406 has a main body portion 467 between its axial inner seat portion 461 and valve seat portion 462 and its inner seat portion 464 and valve seat portion 465. The main body portion 467 is a perforated disc shape.

[0090] The inner seat portion 461 protrudes from the inner peripheral edge on one axial side of the main body portion 467, along the axial direction of the main body portion 467. The valve seat portion 462 protrudes radially outward from the inner seat portion 461, along the axial direction of the main body portion 467, on the same side as the inner seat portion 461.

[0091] The inner seat portion 461 has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 467. The valve seat portion 462 also has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 467. The protruding end face of the inner seat portion 461 and the protruding end face of the valve seat portion 462 are arranged on the same plane, extending in a direction perpendicular to the axis of the seat member 406.

[0092] The inner seat portion 464 protrudes from the inner peripheral edge of the main body portion 467 on the side opposite to the inner seat portion 461 in the axial direction, along the axial direction of the main body portion 467, and toward the side opposite to the inner seat portion 461. The valve seat portion 465 protrudes radially outward from the inner seat portion 464, along the axial direction of the main body portion 467, toward the same side as the inner seat portion 464.

[0093] The inner seat portion 464 has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 467. The valve seat portion 465 also has a flat surface on its protruding end face, that is, the end face opposite to the main body portion 467. The protruding end faces of the inner seat portion 464 and the protruding end faces of the valve seat portion 465 are arranged on the same plane, extending in a direction perpendicular to the axis of the seat member 406.

[0094] As shown in Figure 5, the inner sheet portion 461 has an annular portion 471 and a plurality of protruding portions 472. The annular portion 471 is circular and surrounds the central hole 451. The protruding portions 472 extend outward from the outer peripheral edge of the annular portion 471 in the radial direction. The plurality of protruding portions 472 are arranged at intervals in the circumferential direction of the annular portion 471.

[0095] The inner sheet portion 461 has radial communication grooves 473 that penetrate the annular portion 471 in the radial direction of the annular portion 471. Multiple radial communication grooves 473 are formed in the inner sheet portion 461 at equal intervals in the circumferential direction of the annular portion 471. As shown in Figure 4, the radial communication grooves 473 are formed recessed in the axial direction of the sheet member 406 from the end surface of the inner sheet portion 461 opposite to the main body portion 467.

[0096] As shown in Figure 5, each radial communication groove 473 is in phase with one of the multiple second inner circumferential walls 453 of the central hole 451 in the circumferential direction of the annular portion 471, and communicates with the corresponding second inner circumferential wall 453. Each of the multiple radial communication grooves 473 is provided between adjacent protrusions 472 in the circumferential direction of the annular portion 471.

[0097] The valve seat portion 462 is a non-circular, petal-shaped, irregularly shaped seat. The valve seat portion 462 has multiple (specifically three) valve seat components 475. These valve seat components 475 are identical in shape and are arranged at equal intervals in the circumferential direction of the seat member 406.

[0098] The valve seat component 475 has a pair of extensions 476 and a connecting portion 477. Both extensions 476 extend outward in the radial direction of the annular portion 471 from the outer peripheral edge of the annular portion 471 of the inner seat portion 461. The pair of extensions 476 are spaced apart in the circumferential direction of the annular portion 471.

[0099] The connecting portion 477 connects the radially outer ends of the annular portion 471 of the pair of extension portions 476. The connecting portion 477 extends in the circumferential direction of the annular portion 471. The connecting portion 477 has an arc shape centered on the central axis of the sheet member 406.

[0100] Here, a pair of protruding portions 472 are arranged on the inner side of the seat member 406 of the valve seat component 475, adjacent to each other in the circumferential direction of the inner seat portion 461, and a radial communication groove 473 is arranged between these pairs of protruding portions 472. Therefore, a pair of protruding portions 472 and a radial communication groove 473 are arranged on the inner side of the seat member 406 of each of the multiple valve seat components 475 in the circumferential direction.

[0101] A passage recess 478 is formed inside each of the multiple valve seat components 475, between it and the inner seat portion 461. The passage recess 478 is formed by being surrounded by a part of the inner seat portion 461 and the valve seat component 475. As shown in Figure 4, the passage recess 478 is recessed in the axial direction of the seat member 406 from the protruding end surface of the inner seat portion 461 and the protruding end surface of the valve seat component 475. The bottom surface of the passage recess 478 is formed by the main body portion 467. As shown in Figure 5, a passage recess 478 is formed inside all of the valve seat components 475.

[0102] A passage hole 479 is formed at the center of the passage recess 478 in the circumferential direction of the sheet member 406. The passage hole 479 is positioned between a pair of protruding portions 472 within the passage recess 478 in which it is formed. As shown in Figure 4, the passage hole 479 penetrates the sheet member 406 axially by passing through the main body portion 467 in the axial direction. The passage hole 479 is a straight hole parallel to the central axis of the sheet member 406. As shown in Figure 5, passage holes 479 are formed on the bottom surface of all passage recesses 478.

[0103] As shown in Figure 6, the inner sheet portion 464 has an annular portion 481 and a plurality of protruding portions 482. The annular portion 481 is circular and surrounds the central hole 451. The protruding portions 482 extend outward from the outer peripheral edge of the annular portion 481 in the radial direction. The plurality of protruding portions 482 are arranged at intervals in the circumferential direction of the annular portion 481.

[0104] Multiple communication grooves 483 are formed in the inner sheet portion 464 at equal intervals in the circumferential direction of the annular portion 481, traversing the annular portion 481 in the radial direction. As shown in Figure 4, the communication grooves 483 are formed recessed in the axial direction of the sheet member 406 from the end face of the inner sheet portion 464 opposite to the main body portion 467. The communication grooves 483 form an orifice 484 inside them.

[0105] As shown in Figure 6, each of the multiple communication grooves 483 is in phase with one of the multiple second inner circumferential walls 453 of the central hole 451 in the circumferential direction of the annular portion 481, and communicates with the corresponding second inner circumferential wall 453. Each of the multiple communication grooves 483 is provided between adjacent protruding portions 482 in the circumferential direction of the annular portion 471.

[0106] The valve seat portion 465 is a non-circular, petal-shaped, irregularly shaped seat. The valve seat portion 465 has multiple (specifically three) valve seat components 485. These valve seat components 485 are identical in shape and are arranged at equal intervals in the circumferential direction of the seat member 406.

[0107] In the annular portion 481 of the inner seat portion 464, a communication groove 483 is positioned between two valve seat components 485 adjacent to each other in the circumferential direction of the seat member 406. Therefore, the communication groove 483 is formed in the portion of the inner seat portion 464 that is located outside the valve seat portion 465.

[0108] The valve seat component 485 has a pair of extensions 486 and a connecting portion 487. Both extensions 486 extend radially outward from the outer peripheral edge of the annular portion 481 of the inner seat portion 464. The pair of extensions 486 are spaced apart in the circumferential direction of the annular portion 481. The connecting portion 487 connects the radially outer ends of the pair of extensions 486 of the annular portion 481. The connecting portion 487 extends in the circumferential direction of the annular portion 481. The connecting portion 487 is arc-shaped with respect to the central axis of the seat member 406.

[0109] Here, a pair of protruding portions 482 are arranged on the inner side in the circumferential direction of the seat member 406 of the valve seat component 485, adjacent to the inner seat portion 464 in the circumferential direction. Therefore, a pair of protruding portions 482 are arranged on the inner side in the circumferential direction of each seat member 406 of the multiple valve seat components 485.

[0110] Inside each of the multiple valve seat components 485, a passage recess 488 is formed between it and the inner seat portion 464. The passage recess 488 is formed by being surrounded by a part of the inner seat portion 464 and the valve seat component 485.

[0111] As shown in Figure 4, the passage recess 488 is recessed in the axial direction of the seat member 406 from the protruding end surface of the inner seat portion 464 and the protruding end surface of the valve seat component 485. The bottom surface of the passage recess 488 is formed by the main body portion 467. As shown in Figure 6, passage recesses 488 are formed inside all valve seat components 485.

[0112] A passage hole 489 is formed at the center of the passage recess 488 in the circumferential direction of the sheet member 406. The passage hole 489 is positioned between a pair of protruding portions 482 within the passage recess 488 in which it is formed, in the circumferential direction of the sheet member 406. As shown in Figure 4, the passage hole 489 penetrates the sheet member 406 axially by passing through the main body portion 467 in the axial direction. The passage hole 489 is a straight hole parallel to the central axis of the sheet member 406. As shown in Figure 6, passage holes 489 are formed on the bottom surface of all passage recesses 488.

[0113] Here, the circumferential arrangement pitch of the seat members 406 of the multiple valve seat components 475 shown in Figure 5 is the same as the circumferential arrangement pitch of the seat members 406 of the multiple valve seat components 485 shown in Figure 6. Furthermore, the valve seat components 475 and 485 are offset from each other by half a phase in terms of their arrangement pitch in the circumferential direction of the seat member 406.

[0114] As shown in Figure 5, the passage hole 489 is located between adjacent valve seat components 475 in the circumferential direction of the seat member 406. Therefore, the passage hole 489 is located outside the range of the valve seat portion 462.

[0115] Furthermore, as shown in Figure 6, the passage hole 479 is located between adjacent valve seat components 485 in the circumferential direction of the seat member 406. Therefore, the passage hole 479 is located outside the range of the valve seat portion 465.

[0116] As shown in Figure 4, the passage within the passage hole 479 and the passage within the passage recess 478 into which the passage hole 479 opens constitute the passage portion 491 provided in the sheet member 406. Multiple passage portions 491 (specifically three locations) are provided in the sheet member 406 at equal intervals in the circumferential direction of the sheet member 406. The passage portion 491 communicates with the passage within the radial communication groove 473 and with the orifice 484 within the communication groove 483.

[0117] The passage hole 489 and the passage within the passage recess 488 through which the passage hole 489 opens constitute the passage portion 492 provided in the sheet member 406. Multiple passage portions 492 (specifically three locations) are provided in the sheet member 406 at equal intervals in the circumferential direction of the sheet member 406.

[0118] A seal groove 501 is formed in the sheet member 406 at the axial center of the outer circumference of the main body portion 467. The seal groove 501 is annular and recessed radially inward from the outer surface of the main body portion 467. An O-ring 405 is placed within this seal groove 501.

[0119] The seat member 406 is fitted to the cylindrical portion 433 of the case member 418 at its outer circumference, with its inner seat portion 461 and valve seat portion 462 facing away from the bottom portion 431 of the case member 418. In this state, the O-ring 405 seals the gap between the cylindrical portion 433 of the case member 418 and the seat member 406.

[0120] The case member 418, O-ring 405, and seat member 406 form a case chamber 505 inside the case member 418. The case chamber 505 is located between the bottom 431 of the case member 418 and the seat member 406. The valve member 407, retainers 408, 410, 412, and spring member 409 are located within this case chamber 505. The valve seat portion 465 of the seat member 406 is positioned on the case chamber 505 side.

[0121] The annular seat member 406 and the bottomed cylindrical case member 418 are arranged in the lower chamber 20, which is one of the upper chamber 19 and the lower chamber 20. In this configuration, the valve seat portion 462 of the seat member 406 is positioned on the lower chamber 20 side.

[0122] The case chamber 505 is constantly in communication with the upper chamber 19 via the orifice 484 in the communication groove 483 of the sheet member 406, the intermediate chamber 30 in the second inner peripheral wall 453 of the sheet member 406 and in the groove 26 of the piston rod 21, and the orifice 46 and piston passage portion 37 provided on the piston 18 as shown in Figure 2. As shown in Figure 4, the multiple passage portions 492 of the sheet member 406 are provided facing the lower chamber 20 and are constantly in communication with the lower chamber 20.

[0123] The valve member 407 is flexible. The valve member 407 has an outer diameter equivalent to the outer diameter of the valve seat portion 465 of the seat member 406. The valve member 407 is always in contact with the inner seat portion 464 and can seat on and off the valve seat portion 465. By seating on the entire valve seat portion 465, the valve member 407 closes all passage portions 492. Also, by separating the valve member 407 from any of the valve seat components 485 of the valve seat portion 465, the valve member 407 opens the passage portion 492 inside the separated valve seat component 485.

[0124] The spring member 409 has multiple spring plate portions 442, the extended ends of which are pressed against the outer circumference of the valve member 407. The spring member 409 biases the valve member 407 so that it comes into contact with the valve seat portion 465 of the seat member 406. The valve member 407 seats on the valve seat portion 465 due to the biasing force of the spring member 409, closing the passage portion 492. The valve member 407 deforms against the biasing force of the spring member 409 and separates from the valve seat portion 465, thereby opening the passage portion 492.

[0125] When the valve member 407 moves away from the valve seat portion 465, it connects the multiple passage portions 492 with the case chamber 505. As a result, the lower chamber 20 communicates with the upper chamber 19 via the multiple passage portions 492, the case chamber 505, the orifice 484 in the communication groove 483 of the seat member 406, the intermediate chamber 30, and the orifice 46 and piston passage portion 37 provided on the piston 18 shown in Figure 2. At this time, the valve member 407 shown in Figure 4 suppresses the flow of oil L between itself and the valve seat portion 465, thereby generating a damping force.

[0126] The valve member 407 is a check valve that opens to allow oil liquid L to flow in from the lower chamber 20 to the case chamber 505 through multiple passages 492, while restricting the outflow of oil liquid L from the case chamber 505 to the lower chamber 20 through the passages 492. Here, the passage 491 opens outward from the range of the valve seat portion 465 in the seat member 406. For this reason, the passage 491 is always in communication with the case chamber 505, independently of the valve member 407 which is seated on the valve seat portion 465.

[0127] The third passage 510 consists of multiple passage sections 492, a passage between the valve member 407 and the valve seat section 465 that appear when the valve is opened, a case chamber 505, an orifice 484, an intermediate chamber 30, an orifice 46 shown in Figure 2, and a piston passage section 37. The third passage 510 is opened and closed by the valve member 407 shown in Figure 4. As the piston 18 moves toward the lower chamber 20, the oil liquid L flows out of the third passage 510 from the lower chamber 20, which is the upstream side of the cylinder 2, to the upper chamber 19, which is the downstream side. The third passage 510 is the compression-side passage through which the oil liquid L flows out from the lower chamber 20, which is the upstream side, toward the upper chamber 19, which is the downstream side, during the movement of the piston 18 toward the lower chamber 20, i.e., the compression stroke. At least a part of the compression-side third passage 510, in this case the entirety, is provided in parallel with the compression-side first passage 60 shown in Figure 2. The third passage 510 on the compression side is provided in parallel with the second passage 220 on the compression side, except for a part of the intermediate chamber 30, the orifice 46, and a part of the piston passage 37.

[0128] The valve member 407, the seat member 406 including the valve seat portion 465, the retainer 408, and the spring member 409 constitute the third damping force generating mechanism 511. The third damping force generating mechanism 511 is provided in the compression-side third passage 510. The third damping force generating mechanism 511 opens and closes this third passage 510, suppressing the flow of oil L from this third passage 510 to the upper chamber 19 and generating damping force. The third damping force generating mechanism 511 is a damping force generating mechanism on the compression side.

[0129] The third damping force generating mechanism 511 includes a valve seat portion 465 which is a valve seat and a valve member 407 which is a flexible valve body, and is a check valve mechanism that allows flow in the third passage 510 from the lower chamber 20 which is upstream to the upper chamber 19 which is downstream during the compression stroke, while restricting flow in the direction from the upper chamber 19 which is upstream to the lower chamber 20 which is downstream during the extension stroke. In other words, the third damping force generating mechanism 511 only allows flow in the third passage 510 from the lower chamber 20 which is upstream to the upper chamber 19 which is downstream during the compression stroke.

[0130] The third damping force generating mechanism 511 has its valve seat portion 465 provided on the seat member 406. The third damping force generating mechanism 511, which generates damping force during the compression stroke, is provided separately from the first damping force generating mechanism 40, which generates damping force during the compression stroke, and the valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216, which generate damping force during the compression stroke.

[0131] In the compression-side third damping force generating mechanism 511, neither the valve seat portion 465 nor the valve member 407 that abuts it has a fixed orifice that connects the upper chamber 19 and the lower chamber 20 even when the valve seat portion 465 and the valve member 407 are in contact. In other words, the third passage 510 does not have a fixed orifice that constantly connects the upper chamber 19 and the lower chamber 20. The third passage 510 is not a passage that constantly connects the upper chamber 19 and the lower chamber 20.

[0132] The compression-side third passage 510, which connects the upper chamber 19 and the lower chamber 20, is in parallel with the compression-side first passage 60, which also connects the upper chamber 19 and the lower chamber 20. The compression-side third passage 510, which connects the upper chamber 19 and the lower chamber 20, is in parallel with the compression-side second passage 220, which also connects the upper chamber 19 and the lower chamber 20. The first damping force generating mechanism 40 is provided in the first passage 60. The valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216 are provided in the second passage 215. The third damping force generating mechanism 511 is provided in the third passage 510. Therefore, the compression-side first damping force generating mechanism 40, the valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216, and the third damping force generating mechanism 511 are all arranged in parallel.

[0133] The valve member 403 is flexible. The outer diameter of the valve member 403 is the same as the outer diameter of the valve seat portion 462 of the seat member 406 and the same as the outer diameter of the retainer 100. The valve member 403 is always in contact with the inner seat portion 461 and can seat on and off the valve seat portion 462. When the valve member 403 is seated on the entire valve seat portion 462, it closes all the passage portions 491. Also, when the valve member 403 is separated from any of the valve seat components 475 of the valve seat portion 462, it opens the passage portion 491 inside the separated valve seat component 475.

[0134] The retainer 402 has an outer diameter smaller than the outer diameter of the valve member 403 and smaller than the outer diameter of the inner seat portion 461.

[0135] The spring member 401 is flexible. The spring member 401 has a base plate portion 513 and a plurality of spring plate portions 514. The base plate portion 513 is a perforated circular flat plate. The mounting shaft portion 28 is fitted into the inner circumference of the base plate portion 513. The outer diameter of the base plate portion 513 is slightly larger than the outer diameter of the retainer 402. The base plate portion 513 abuts against the retainer 402.

[0136] Multiple spring plate portions 514 extend radially from the outer peripheral edge of the base plate portion 513. The further outward the multiple spring plate portions 514 are from the base plate portion 513 in the axial direction, the further they are from the base plate portion 513 in the radial direction.

[0137] The spring member 401 has a maximum outer diameter smaller than the outer diameter of the valve member 403. The spring member 401 has multiple spring plate portions 514 that extend from the base plate portion 513 toward the valve member 403 in the axial direction of the base plate portion 513. The extended ends of the multiple spring plate portions 514 of the spring member 401 are pressed against the outer circumference of the valve member 403. As a result, the multiple spring plate portions 514 of the spring member 401 bias the outer circumference of the valve member 403 to contact the valve seat portion 462 of the seat member 406. The valve member 403 seats on the valve seat portion 462 due to the biasing force of the spring member 401 and closes the passage portion 491. The valve member 403 deforms against the biasing force of the spring member 401 and separates from the valve seat portion 462, opening the passage portion 491.

[0138] The valve member 403 is located within the lower chamber 20. By moving away from the valve seat portion 462, the valve member 403 connects the case chamber 505 and the lower chamber 20 via a plurality of passage portions 491 in the seat member 406. At this time, the valve member 403 suppresses the flow of oil L between itself and the valve seat portion 462, thereby generating a damping force. The valve member 403 is a check valve that discharges the oil L from the case chamber 505 to the lower chamber 20 via the plurality of passage portions 491, while restricting the inflow of oil L from the lower chamber 20 into the case chamber 505 via the passage portions 491. Here, the passage portions 492 open outward from the range of the valve seat portion 462 in the seat member 406. For this reason, the passage portions 492 are always in communication with the lower chamber 20, independently of the valve member 403 seated on the valve seat portion 462.

[0139] The radial communication groove 473 formed in the inner sheet portion 461 of the sheet member 406 serves as a radial passage 517. The radial passage 517 communicates with the intermediate chamber 30.

[0140] The piston passage 37 shown in Figure 2, the orifice 46, the intermediate chamber 30, the orifice 484 shown in Figure 4, the case chamber 505, the passage 491, the radial passage 517, and the passage between the valve member 403 and the valve seat 462 that appear when the valve is opened constitute the third passage 520.

[0141] The third passage 520 is opened and closed by a valve member 403. The third passage 520 allows oil L to flow from the upper chamber 19, which is the upstream side of the cylinder 2, to the lower chamber 20, which is the downstream side, as the piston 18 moves toward the upper chamber 19. The third passage 520 is the extension-side passage through which oil L flows from the upper chamber 19, which is the upstream side, toward the lower chamber 20, which is the downstream side, as the piston 18 moves toward the upper chamber 19, that is, during the extension stroke. At least a portion of the extension-side third passage 520 is provided separately from the extension-side first passage 140 and the extension-side second passage 215. At least a portion of the third passage 520 is provided in parallel with the first passage 140, in this case a portion. The third passage 520 is in parallel with the first passage 140, except for a portion on the upper chamber 19 side of the orifice 46 of the piston passage section 37. The third passage 520 is parallel to the second passage 215, except for a portion of the piston passage 37 on the upper chamber 19 side of the orifice 46, the orifice 46, and a portion of the intermediate chamber 30 on the orifice 46 side.

[0142] The radial passage 517 connects the intermediate chamber 30 of the third passage 520 and the passage portion 491 without passing through the orifice 484 and the case chamber 505. The radial passage 517 communicates from the intermediate chamber 30 to the valve seat portion 462. In other words, the radial passage 517 communicates from the central hole 451 to the third damping force generating mechanism 521, which will be described later and includes the valve seat portion 462.

[0143] The valve member 403, the seat member 406 including the valve seat portion 462, the retainer 402, and the spring member 401 constitute the third damping force generating mechanism 521. The third damping force generating mechanism 521 is provided in the extension-side third passage 520 and opens and closes this third passage 520. The third damping force generating mechanism 521 generates damping force by suppressing the flow of oil L from the third passage 520 to the lower chamber 20. The third damping force generating mechanism 521 is an extension-side damping force generating mechanism. The third damping force generating mechanism 521, which generates damping force in the extension stroke, is provided separately from the first damping force generating mechanism 40, which generates damping force in the extension stroke. The third damping force generating mechanism 521, which generates damping force in the extension stroke, is provided separately from the sub-valve mechanism 201 and hard valve mechanism 212 of the second damping force generating mechanism 216, which generate damping force in the extension stroke. The third damping force generating mechanism 521 includes a radial passage 517. In the extension stroke, the oil L flows to the lower chamber 20 via the intermediate chamber 30 and the radial passage 517.

[0144] The third damping force generating mechanism 521 includes a valve seat portion 462 which is a valve seat and a valve member 403 which is a flexible valve body, and is a check valve mechanism that allows the flow of oil L in the direction from the upper chamber 19 which is upstream to the lower chamber 20 which is downstream during the extension stroke of the third passage 520 including the case chamber 505, while restricting the flow of oil L in the direction from the lower chamber 20 which is upstream to the upper chamber 19 which is downstream during the compression stroke. In other words, the third damping force generating mechanism 521 only allows the flow in the direction from the upper chamber 19 which is upstream to the lower chamber 20 which is downstream during the extension stroke of the third passage 520 including the case chamber 505.

[0145] The extension-side third damping force generating mechanism 521 does not have a fixed orifice formed in either the valve seat portion 462 or the valve member 403 that abuts it, which would connect the upper chamber 19 and the lower chamber 20 even when the valve seat portion 462 and the valve member 403 are in contact. In other words, the extension-side third damping force generating mechanism 521 does not connect the upper chamber 19 and the lower chamber 20 when the valve seat portion 462 and the valve member 403 are in contact. To put it another way, the third passage 520 is not provided with a fixed orifice that would keep the upper chamber 19 and the lower chamber 20 in constant contact. The third passage 520 is not a passage that keeps the upper chamber 19 and the lower chamber 20 in constant contact.

[0146] The extension-side first damping force generating mechanism 40, the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216, and the extension-side third damping force generating mechanism 521 operate before the extension-side first damping force generating mechanism 40 and the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 when the piston speed, which is the axial movement speed of the piston 18, is a first speed. Furthermore, the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 operates when the extension-side third damping force generating mechanism 521 is operating when the piston speed is faster than the first speed. Furthermore, the extension-side first damping force generating mechanism 40 operates when the extension-side third damping force generating mechanism 521 is operating and the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 is operating when the piston speed is faster than the second speed.

[0147] The compression-side first damping force generating mechanism 42, the compression-side valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216, and the compression-side third damping force generating mechanism 511 operate before the compression-side third damping force generating mechanism 511 at the 11th piston speed. Furthermore, the compression-side valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216 operate when the compression-side third damping force generating mechanism 511 is operating at the 12th piston speed, which is faster than the 11th speed. Furthermore, the compression-side first damping force generating mechanism 42 operates when the piston speed is faster than the 12th speed, the compression-side third damping force generating mechanism 511 is operating, and the compression-side valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216 are operating.

[0148] As described above, the shock absorber 1 includes: an extension-side first damping force generating mechanism 40 provided in the extension-side first passage 140 to adjust the flow of oil liquid L moving within the first passage 140; a compression-side first damping force generating mechanism 42 provided in the compression-side first passage 60 to adjust the flow of oil liquid L moving within the first passage 60; and a second damping force generating mechanism provided in the second passages 215 and 220 arranged in parallel with the first passages 140 and 60 to adjust the flow of oil liquid L moving within the second passages 215 and 220. The structure 216 includes an extension-side third damping force generating mechanism 521 provided in an extension-side third passage 520 arranged in parallel with the extension-side first passage 140 and the extension-side second passage 215, which adjusts the flow of oil liquid L moving within the third passage 520, and a compression-side third damping force generating mechanism 511 provided in a compression-side third passage 510 arranged in parallel with the compression-side first passage 60 and the compression-side second passage 220, which adjusts the flow of oil liquid L moving within the third passage 510.

[0149] Furthermore, the extension-side third damping force generating mechanism 521 operates before the extension-side first damping force generating mechanism 40 and the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 when the piston speed, which is the axial movement speed of the piston 18 during the extension stroke, is a first speed. Also, the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 operates when the extension-side third damping force generating mechanism 521 is operating when the piston speed during the extension stroke is a second speed that is faster than the first speed. Furthermore, the extension-side first damping force generating mechanism 40 operates when the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 is operating when the piston speed during the extension stroke is a third speed that is faster than the second speed.

[0150] Furthermore, the compression-side third damping force generating mechanism 511 operates before the compression-side first damping force generating mechanism 42 and the compression-side valve mechanism 205 and compression-side sub-valve mechanism 202 of the second damping force generating mechanism 216 when the piston speed in the compression stroke is at the 11th speed. Also, the valve mechanism 205 and sub-valve mechanism 202 of the compression-side second damping force generating mechanism 216 operate when the compression-side third damping force generating mechanism 511 operates when the piston speed in the compression stroke is at the 12th speed, which is faster than the 11th speed. Furthermore, the compression-side first damping force generating mechanism 42 operates when the valve mechanism 205 and sub-valve mechanism 202 of the compression-side second damping force generating mechanism 216 operate when the piston speed in the compression stroke is at the 13th speed, which is faster than the 12th speed.

[0151] The second damping force generating mechanism 216 includes a sub-valve 82 that adjusts the flow of oil liquid L in the second passages 215 and 220, and a hard valve 211 and a variable valve 92 that partition the second passages 215 and 220 to form variable volume chambers 191 and 192 capable of storing oil liquid L, and which are operated by the oil liquid L flowing due to the movement of the piston 18 to vary the volume of the variable volume chambers 191 and 192. The sub-valve 82 and the hard valve 211 and variable valve 92 are arranged in series within the second passages 215 and 220. The sub-valve 82 is annular and has an outer peripheral valve portion 166 that allows one flow of oil liquid L and an inner peripheral valve portion 167 that allows the other flow of oil liquid L. The second damping force generating mechanism 216 includes a pilot case 84 fixed to the piston rod 21 and forming part of the second passages 215 and 220, a hard valve 211 positioned to contact the pilot case 84 and operating to allow one flow of the oil liquid L, and a variable valve 92 positioned inside the pilot case 84 and operating to allow the other flow of the oil liquid L, and contacting the hard valve 211 to form a variable volume chamber 192 between itself and the hard valve 211.

[0152] The second damping force generating mechanism 216 includes a pilot case 84 fixed to the piston rod 21 and forming part of the second passages 215 and 220, a sub-valve 82 positioned in contact with one axial side of the pilot case 84 to adjust the flow of oil L in the second passages 215 and 220, a hard valve 211 positioned in contact with the other axial side of the pilot case 84 to adjust the flow of oil L in the second passage 215, and a variable valve 92 provided between the pilot case 84 and the hard valve 211, which contacts the hard valve 211 to form a variable volume chamber 192 between itself and the hard valve 211 and opens and closes with the flow of oil L. The third damping force generating mechanism 511 includes a seat member 406 fixed to the piston rod 21 and forming part of the third passage 510, and a valve member 407 that contacts the seat member 406 and opens when separated from the seat member 406 by the flow of oil L. The third damping force generating mechanism 521 is fixed to the piston rod 21 and includes a seat member 406 in which a part of the third passage 520 is formed, and a valve member 403 that contacts the seat member 406 and opens when separated from the seat member 406 by the flow of oil liquid L.

[0153] The configuration described above is shown in the hydraulic circuit diagram in Figure 7. As shown in Figure 7, a first passage 140 is provided connecting the upper chamber 19 and the lower chamber 20. A first damping force generating mechanism 40 is provided in the first passage 140, and a fixed orifice 132 is provided in parallel with the first damping force generating mechanism 40. Also, second passages 215 and 220 are provided in parallel with the first passage 140, connecting the upper chamber 19 and the lower chamber 20. Common to the second passages 215 and 220, in order from the upper chamber 19 side, are an orifice 46, an intermediate chamber 30, a communicating orifice 142, and a back pressure chamber 170. The back pressure chamber 170 controls the opening of the valve of the first damping force generating mechanism 40 with its pressure. On the side of the back pressure chamber 170 opposite the communication orifice 142, the second passage 215 and the second passage 220 are separated, with a sub-valve mechanism 201 provided in the second passage 215 and a sub-valve mechanism 202 provided in the second passage 220. On the lower chamber 20 side of the sub-valve mechanisms 201 and 202, a volume variable chamber 191 of the damping force variable mechanism 193 is provided, common to the second passages 215 and 220. The second passage 215 has a flow path that connects the volume variable chamber 192 of the damping force variable mechanism 193 to the lower chamber 20, and a flow path that connects the volume variable chamber 191 to the lower chamber 20 via a hard valve mechanism 212. The second passage 220 has a flow path that connects the volume variable chamber 192 to the lower chamber 20, which is common to the second passage 215, and has a flow path that allows oil liquid L to flow from the lower chamber 20 to the volume variable chamber 191 via a valve mechanism 205. Furthermore, a first passage 60 is provided connecting the lower chamber 20 and the upper chamber 19, and a first damping force generating mechanism 42 is provided in the first passage 60. In addition, third passages 510 and 520 are provided connecting the lower chamber 20 and the intermediate chamber 30, with a third damping force generating mechanism 511 provided in the third passage 510 and a third damping force generating mechanism 521 provided in the third passage 520. An orifice 484 is provided on the upper chamber 19 side of the third damping force generating mechanism 511 and the third damping force generating mechanism 521, and is common to the third passages 510 and 520.

[0154] As shown in Figure 1, the base valve 25 described above is provided between the cylinder bottom 12 of the outer cylinder 4 and the inner cylinder 3. This base valve 25 has a base valve member 301 that separates the lower chamber 20 and the reservoir chamber 6, a disc 302 provided on the lower side of the base valve member 301, i.e., the reservoir chamber 6 side, a disc 303 provided on the upper side of the base valve member 301, i.e., the lower chamber 20 side, and mounting pins 304 for attaching the discs 302 and 303 to the base valve member 301.

[0155] The base valve member 301 has an annular shape through which a mounting pin 304 is inserted in the radial center. The base valve member 301 has a plurality of passage holes 305 for circulating oil L between the lower chamber 20 and the reservoir chamber 6, and a plurality of passage holes 306 for circulating oil L between the lower chamber 20 and the reservoir chamber 6, located radially outside these passage holes 305. The disk 302 on the reservoir chamber 6 side allows the flow of oil L from the lower chamber 20 to the reservoir chamber 6 through the passage holes 305, while suppressing the flow of oil L from the reservoir chamber 6 to the lower chamber 20 through the passage holes 305. The disk 303 allows the flow of oil L from the reservoir chamber 6 to the lower chamber 20 through the passage holes 306, while suppressing the flow of oil L from the lower chamber 20 to the reservoir chamber 6 through the passage holes 306.

[0156] Disc 302, together with the base valve member 301, constitutes a compression-side damping valve 307 that opens during the compression stroke of the shock absorber 1 to allow oil L to flow from the lower chamber 20 to the reservoir chamber 6 and generate damping force. Disc 303, together with the base valve member 301, constitutes a suction valve 308 that opens during the extension stroke of the shock absorber 1 to allow oil L to flow from the reservoir chamber 6 into the lower chamber 20. The suction valve 308 primarily functions to compensate for the lack of fluid caused by the extension of the piston rod 21 from the cylinder 2 by allowing fluid to flow from the reservoir chamber 6 to the lower chamber 20 without substantially generating damping force.

[0157] Next, the operation of the piston 18 and other components attached to the piston rod 21 of the shock absorber 1 in the first embodiment will be described.

[0158] First, let's assume that there is no variable damping force mechanism 193. In the extension stroke, when the piston rod 21 moves in the extension direction, in the extremely low-speed range where the piston speed, which is the axial movement speed of the piston 18, is between 0 and less than the first speed v1 (greater than 0), the oil L from the upper chamber 19 flows from the piston passage 37 through the fixed orifice 132 to the lower chamber 20. Therefore, a damping force with orifice characteristics (where the damping force is approximately proportional to the square of the piston speed) is generated. As a result, the damping force characteristics with respect to piston speed in the extremely low-speed range of the extension stroke are relatively hard, with a high rate of increase in damping force as the piston speed increases.

[0159] When the piston speed increases to a very low speed range that is above the first speed v1 but below the second speed v2 (which is faster than the first speed v1), the oil L from the upper chamber 19 flows into the lower chamber 20 through the piston passage 37 and orifice 46 of the piston 18, the intermediate chamber 30 of the piston rod 21 and seat member 406, the orifice 484 of the seat member 406, the case chamber 505, and the passage 491 of the seat member 406, opening the third damping force generating mechanism 521. As a result, a damping force with valve characteristics (where the damping force is approximately proportional to the piston speed) is generated. Consequently, the damping force characteristics with respect to piston speed in the very low speed range of the extension stroke are softer, as the rate of increase in damping force with increasing piston speed is lower than in the extremely low speed range of the extension stroke.

[0160] As the piston speed increases to a low speed range that is above the second speed v2 but below the third speed v3 (faster than the second speed v2), the oil L from the upper chamber 19 flows not only through the third passage 520, which includes the gap between the separated valve member 403 and valve seat portion 462 of the third damping force generating mechanism 521, but also from the piston passage portion 37, opening the piston main valve 138 of the first damping force generating mechanism 40, and flowing into the lower chamber 20 through the first passage 140, which includes the gap between the piston main valve 138 and the valve seat portion 47 of the piston 18. As a result, the damping force characteristics with respect to piston speed in the low speed range of the extension stroke become softer, as the rate of increase in damping force with respect to piston speed is lower than in the very low speed range of the extension stroke.

[0161] When the piston speed is in the medium speed range, which is greater than or equal to the third speed v3 and less than or equal to the fourth speed v4, the oil L from the upper chamber 19 flows to the lower chamber 20 through the third passage 520, which includes the gap between the separated valve member 403 and valve seat portion 462 of the third damping force generating mechanism 521, and flows to the lower chamber 20 through the first passage 140, which includes the gap between the separated piston main valve 138 and valve seat portion 47 of the first damping force generating mechanism 40, in addition to the flow to the lower chamber 20. The air flows into the back pressure chamber 170 via the piston passage 37 and orifice 46 of the piston rod 18, the intermediate chamber 30 of the piston rod 21, and the communication orifice 142 of the communication disc 78. This opens the sub-valve mechanism 201, allowing the air to pass through the passage between the seat disc 81 and the inner circumferential valve portion 167 of the sub-valve 82. This opens the hard valve mechanism 212, allowing the air to pass through the passage between the hard valve 211 and the valve seat portion 156 of the pilot case 84, and then into the lower chamber 20. As a result, the damping force characteristics with respect to piston speed in the mid-speed range of the extension stroke are softer, with the rate of increase in damping force with respect to piston speed being lower than in the low-speed range of the extension stroke.

[0162] When the piston speed reaches a high speed range of the fourth speed v4 or higher, the relationship between the force (hydraulic pressure) acting on the pilot valve 74 is such that the opening force applied from the piston passage 37 becomes greater than the closing force applied from the back pressure chamber 170. Therefore, in this high-speed range, as the piston speed increases, the piston main valve 138 of the first damping force generating mechanism 40 opens further away from the valve seat portion 47 of the piston 18 than in the low-speed and medium-speed ranges. Consequently, the oil liquid L in the upper chamber 19 flows to the lower chamber 20 via the third passage 520, which includes the gap between the separated valve member 403 and the valve seat portion 462 of the third damping force generating mechanism 521, and via the second passage 215, which includes the gap between the separated hard valve 211 and the valve seat portion 156 of the hard valve mechanism 212, as well as more oil L flows to the lower chamber 20 via the first passage 140, which includes the passage between the piston main valve 138 and the valve seat portion 47 of the piston 18. Therefore, the damping force characteristics with respect to piston speed in the high-speed range of the extension stroke are such that the rate of increase in damping force with respect to piston speed is lower than in the mid-speed range of the extension stroke, resulting in an even softer characteristic.

[0163] During the compression stroke, when the piston rod 21 moves in the compression direction, in the very low speed range where the axial movement speed of the piston 18 is between 0 and a fifth speed v5 greater than 0, the oil L from the lower chamber 20 flows from the fixed orifice 132 through the piston passage 37 to the upper chamber 19, generating a damping force with orifice characteristics. For this reason, the damping force characteristics with respect to piston speed in the extremely low speed range of the compression stroke are relatively hard, with a high rate of increase in damping force as the piston speed increases.

[0164] As the piston speed increases to a very low speed range, above the fifth speed v5 and below the sixth speed v6 (faster than the fifth speed v5), the oil L from the lower chamber 20 flows through the passage 492 of the seat member 406, opening the third damping force generating mechanism 511, and through the case chamber 505, the orifice 484 of the seat member 406, the intermediate chamber 30 of the piston rod 21 and seat member 406, the orifice 46 of the piston 18 and the piston passage 37, into the upper chamber 19. Thus, a damping force characteristic of the valve is generated. For this reason, the damping force characteristic with respect to piston speed in the very low speed range of the compression stroke becomes softer, as the rate of increase in damping force with increasing piston speed is lower than in the extremely low speed range of the compression stroke.

[0165] As the piston speed increases to the low-to-medium-high speed range of the sixth speed v6 or higher, the oil L from the lower chamber 20 flows to the upper chamber 19 through the third passage 510, which includes the gap between the separated valve member 407 and the valve seat portion 465 of the third damping force generating mechanism 511. In addition, it is introduced into the compression-side piston passage portion 39, opening the piston main valve 58 of the first damping force generating mechanism 42, and flowing to the upper chamber 19 through the gap between the piston main valve 58 and the valve seat portion 49. Therefore, the damping force characteristics with respect to piston speed in the low-to-medium-high speed range of the compression stroke are softer, as the rate of increase in damping force with increasing piston speed is lower than in the very low speed range of the compression stroke.

[0166] The above describes the operation assuming the variable damping force mechanism 193 is absent. However, in the first embodiment, the variable damping force mechanism 193 varies the damping force according to the piston frequency, even when the piston speed is the same.

[0167] During the extension stroke, when the piston speed reaches a third piston speed (third speed) that is faster than the first piston speed (first speed) at which the third damping force generating mechanism 521 opens and allows the oil L in the upper chamber 19 to flow to the lower chamber 20 via the third passage 520, the first damping force generating mechanism 40 opens and allows the oil L in the upper chamber 19 to flow to the lower chamber 20 via the first passage 140. When the piston speed reaches a second piston speed (second speed) between the first and third piston speeds, the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 opens while the third damping force generating mechanism 521 is open. In other words, when the piston speed reaches the second piston speed, the oil L in the upper chamber 19 flows into the lower chamber 20 through the third passage 520, which includes the opened third damping force generating mechanism 521, and also flows from the intermediate chamber 30 of the piston rod 21 through the communication orifice 142 of the communication disc 78 into the back pressure chamber 170, which opens the sub-valve mechanism 201, and flows through the passage between the inner circumferential valve portion 167 of the sub-valve 82 and the seat disc 81, and is introduced into the volume variable chamber 191 of the damping force variable mechanism 193. Then, the variable valve 92 of the damping force variable mechanism 193 elastically deforms in a direction toward the hard valve 211 due to the oil L introduced into the volume variable chamber 191, expanding the volume of the volume variable chamber 191 while decreasing the volume of the volume variable chamber 192. At that time, the oil L in the variable volume chamber 192 is discharged to the lower chamber 20 through the passage in the passage hole 185 of the valve disc 96 and the passage in the notch 197 of the valve disc 97. When the piston speed reaches the third piston speed (third speed), the oil L in the upper chamber 19 opens the third damping force generating mechanism 521 and flows to the lower chamber 20 through the third passage 520, and also opens the sub-valve mechanism 201 and is introduced into the variable volume chamber 191, and further opens the first damping force generating mechanism 40 and flows to the lower chamber 20 through the first passage 140.

[0168] Here, during the extension stroke when the piston frequency is high, the amplitude of the piston 18 is small, and the amount of oil L introduced from the upper chamber 19 to the variable volume chamber 191 is small. For this reason, each time the extension stroke occurs, the variable valve 92 deforms as described above, introducing oil L from the upper chamber 19 to the variable volume chamber 191. As a result, the flow rate of oil L flowing from the upper chamber 19 to the lower chamber 20 via the first passage 140 while opening the first damping force generating mechanism 40 is reduced. In addition, by introducing oil L from the upper chamber 19 to the variable volume chamber 191, the pressure rise in the back pressure chamber 170 is suppressed compared to when there is no variable volume chamber 191, making it easier for the first damping force generating mechanism 40 to open. As a result, the damping force on the extension side becomes softer. At this time, the hard valve mechanism 212 does not open.

[0169] On the other hand, when the piston frequency is low, the amplitude of the piston 18 is large, and the amount of oil L introduced from the upper chamber 19 to the variable volume chamber 191 is also large. For this reason, in the initial stage of the extension stroke, oil L flows from the upper chamber 19 to the variable volume chamber 191, as described above, but thereafter the variable valve 92 comes into contact with the retainers 94 and 95 and stops, and oil L stops flowing from the upper chamber 19 to the variable volume chamber 191. As oil L stops flowing from the upper chamber 19 to the variable volume chamber 191, the pressure in the variable volume chamber 191 rises, and the pressure in the back pressure chamber 170 between the variable volume chamber 191 and the upper chamber 19 also rises, creating a state that suppresses the opening of the piston main valve 138 of the first damping force generating mechanism 40. In other words, the first damping force generating mechanism 40 makes it difficult for the piston main valve 138 to open, and the oil liquid L flows mainly from the upper chamber 19 to the lower chamber 20 via the fixed orifice 132 and the third damping force generating mechanism 521, resulting in a harder damping force on the extension side.

[0170] Furthermore, as the pressure in the back pressure chamber 170 increases, the oil liquid L opens the hard valve mechanism 212 and flows into the lower chamber 20 through the second passage 215, which includes the gap between the hard valve 211 and the valve seat portion 156.

[0171] As a result, the rebound damping force at low piston frequencies is higher than the rebound damping force at high piston frequencies, resulting in a harder characteristic.

[0172] During the compression stroke, when the piston speed reaches a 13th piston speed (third speed), which is faster than the 11th piston speed (first speed) at which the third damping force generating mechanism 511 opens and allows the oil L from the lower chamber 20 to flow to the upper chamber 19 via the third passage 510, the first damping force generating mechanism 42 opens and allows the oil L from the lower chamber 20 to flow to the upper chamber 19 via the first passage 60. When the piston speed reaches a 12th piston speed (second speed), which is between the 11th and 13th piston speeds, the valve mechanism 205 and the compression-side sub-valve mechanism 202 of the second damping force generating mechanism 216 open, with the third damping force generating mechanism 511 already open. In other words, when the piston speed reaches the twelfth piston speed, the oil L in the lower chamber 20 flows into the upper chamber 19 through the third passage 510, which includes the opened third damping force generating mechanism 511, and is introduced into the variable volume chamber 192 through the passage in the notch 197 of the valve disc 97 and the passage in the passage hole 185 of the valve disc 96, and is introduced into the variable volume chamber 191 through the passage between the variable valve 92 and valve disc 96 of the valve mechanism 205, which opens, and flows into the upper chamber 19 through the passage between the outer peripheral valve portion 166 and valve seat portion 152 of the sub-valve mechanism 202, which opens, the back pressure chamber 170, the communicating orifice 142, the intermediate chamber 30, the orifice 46, and the piston passage portion 37.

[0173] Patent Document 1, mentioned above, discloses a shock absorber in which the damping force is variable in response to the piston frequency by having a variable-volume chamber. However, there is a need for a shock absorber that can generate damping force more effectively.

[0174] The shock absorber 1 of the first embodiment includes a first damping force generating mechanism 40 provided in the extension-side first passage 140 to adjust the flow of oil liquid L moving within the first passage 140, a first damping force generating mechanism 42 provided in the compression-side first passage 60 to adjust the flow of oil liquid L moving within the first passage 60, and a second damping force generating mechanism provided in the second passages 215 and 220 arranged in parallel with the first passages 140 and 60 to adjust the flow of oil liquid L moving within the second passages 215 and 220. The mechanism 216 includes a third damping force generating mechanism 521 provided in the extension-side third passage 520, which is arranged in parallel with the extension-side first passage 140 and the extension-side second passage 215, and which adjusts the flow of oil L moving within the third passage 520, and a third damping force generating mechanism 511 provided in the compression-side third passage 510, which is arranged in parallel with the compression-side first passage 60 and the compression-side second passage 220, and which adjusts the flow of oil L moving within the third passage 510. The third damping force generating mechanism 521 operates before the first damping force generating mechanism 40 and the sub-valve mechanism 201 of the second damping force generating mechanism 216 when the piston speed, which is the axial movement speed of the piston 18 in the extension stroke, is a first speed. The sub-valve mechanism 201 of the second damping force generating mechanism 216 operates when the extension-side third damping force generating mechanism 521 is operating when the piston speed in the extension stroke is faster than the first speed, which is a second speed. Furthermore, the first damping force generating mechanism 40 operates when the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 is operating at a third speed in which the piston speed during the extension stroke is faster than the second speed. The third damping force generating mechanism 511 operates when the piston speed during the compression stroke is an eleventh speed, before the first damping force generating mechanism 42 and the valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216. Furthermore, the valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216 operate when the third damping force generating mechanism 511 is operating at a twelfth speed in which the piston speed during the compression stroke is faster than the eleventh speed. Furthermore, the first damping force generating mechanism 42 operates when the valve mechanism 205 and sub-valve mechanism 202 of the second damping force generating mechanism 216 are operating at a thirteenth speed in which the piston speed during the compression stroke is faster than the twelfth speed. Therefore, the shock absorber 1 can generate damping force more effectively.

[0175] Furthermore, the shock absorber 1 includes a second damping force generating mechanism 216 which comprises a sub-valve 82 that adjusts the flow of oil L in the second passages 215 and 220, and a hard valve 211 and a variable valve 92 that partition the second passages 215 and 220 to form variable volume chambers 191 and 192 capable of storing oil L, and which are operated by the oil L flowing due to the movement of the piston 18 to change the volume of the variable volume chambers 191 and 192. If the variable valve 92 operates before the third damping force generating mechanisms 511 and 521 operate, the rise of the damping force generated by the third damping force generating mechanisms 511 and 521 will be worsened. However, by providing the sub-valve 82, the shock absorber 1 can suppress the variable valve 92 from operating before the third damping force generating mechanisms 511 and 521 operate, thereby suppressing the deterioration of the rise of the damping force generated by the third damping force generating mechanisms 511 and 521.

[0176] Furthermore, in the shock absorber 1, the sub-valve 82, the hard valve 211, and the variable valve 92 are arranged in series within the second passages 215 and 220. Because the shock absorber 1 arranges the sub-valve 82, the hard valve 211, and the variable valve 92 in series in this way, it can reliably prevent the variable valve 92 from operating before the third damping force generating mechanisms 511 and 521 operate, thereby reliably preventing deterioration of the damping force rise of the third damping force generating mechanisms 511 and 521.

[0177] Furthermore, the shock absorber 1 has a sub-valve 82 that is annular in shape and has an outer circumferential valve portion 166 that allows the flow of the oil liquid L in one direction and an inner circumferential valve portion 167 that allows the flow of the oil liquid L in the other direction. As a result, the shock absorber 1 has a sub-valve 82 that allows bidirectional flow, and a single sub-valve 82 can be used to configure check valves for both the extension and compression sides. Therefore, the shock absorber 1 can have a shorter axial length compared to a configuration in which the extension and compression sides are controlled by separate discs, and the second damping force generating mechanism 216 can be miniaturized.

[0178] Furthermore, the shock absorber 1 includes a pilot case 84 to which the second damping force generating mechanism 216 is fixed to the piston rod 21 and in which a part of the second passages 215 and 220 is formed, a hard valve 211 which is arranged to be in contact with the pilot case 84 and operates to allow one flow of the oil liquid L, and a variable valve 92 which is arranged inside the pilot case 84 and operates to allow the other flow of the oil liquid L, and forms a variable volume chamber 192 between itself and the hard valve 211 by contacting it. In this way, the shock absorber 1 has the variable valve 92 inside the pilot case 84 of the second damping force generating mechanism 216, making it possible to miniaturize the second damping force generating mechanism 216. Furthermore, the shock absorber 1 makes it possible to further miniaturize the second damping force generating mechanism 216 because the variable valve 92 forms a variable volume chamber 192 between itself and the hard valve 211 by contacting it.

[0179] Furthermore, the shock absorber 1 includes a second damping force generating mechanism 216, which is fixed to the piston rod 21 and has a pilot case 84 in which a part of the second passages 215 and 220 is formed; a sub-valve 82 positioned in contact with one axial side of the pilot case 84 and adjusting the flow of oil liquid L in the second passages 215 and 220; a hard valve 211 positioned in contact with the other axial side of the pilot case 84 and adjusting the flow of oil liquid L in the second passage 215; and a variable valve 92 provided between the pilot case 84 and the hard valve 211, which contacts the hard valve 211 to form a variable volume chamber 192 between itself and the hard valve 211 and opens and closes with the flow of oil liquid L. The third damping force generating mechanism 511 includes a seat member 406 fixed to the piston rod 21 and in which a part of the third passage 510 is formed; and a valve member 407 that contacts the seat member 406 and opens when separated from the seat member 406 by the flow of oil liquid L. The third damping force generating mechanism 521 is fixed to the piston rod 21 and includes a seat member 406 in which a part of the third passage 520 is formed, and a valve member 403 that contacts the seat member 406 and opens when separated from the seat member 406 by the flow of the oil liquid L. Therefore, the shock absorber 1 can generate damping force more effectively.

[0180] Furthermore, the shock absorber 1 has a damping force variable mechanism 193 in parallel with the third damping force generating mechanisms 511 and 521. Since the function of the damping force variable mechanism 193 does not affect the function of the third damping force generating mechanisms 511 and 521, the waveform (in other words, performance) of the damping force characteristics of the third damping force generating mechanisms 511 and 521 alone can be maintained. Therefore, even when the third damping force generating mechanisms 511 and 521 and the damping force variable mechanism 193 are combined in parallel, the shock absorber 1 can reduce the transmission of unpleasant vibrations to the vehicle body by the damping force variable mechanism 193 while simultaneously achieving the improved vibration damping performance at low vehicle speeds that is the effect of the third damping force generating mechanisms 511 and 521, without mutual interference.

[0181] [Second Embodiment] Next, the buffer of the second embodiment will be described, mainly based on Figures 8 and 9, with reference to Figures 1 to 7, focusing on the differences from the first embodiment. Parts common to the first embodiment will be represented by the same designation and reference numerals.

[0182] As shown in Figure 8, the buffer 1A of the second embodiment is equipped with a pilot case 84A that is partially different from the pilot case 84, replacing the pilot case 84. The pilot case 84A has a seat portion 152A that is lower in axial height than the valve seat portion 152 of the pilot case 84, replacing the valve seat portion 152.

[0183] In the second embodiment of the shock absorber 1A, the configuration between the communicating disk 78 and the bottom 151 of the pilot case 84A differs from that of the first embodiment of the shock absorber 1. In the second embodiment of the shock absorber 1A, the regulating member 79, the multiple (specifically two) sheet disks 81, the one sub-valve 82, and the one retainer 83 that were provided in the first embodiment of the shock absorber 1 are not provided.

[0184] In the buffer 1A of the second embodiment, a retainer 600, a first valve member 601, a second valve member 602, a third valve member 603, a fourth valve member 604, a fifth valve member 605, and a retainer 606 are provided between the communicating disk 78 and the bottom 151 of the pilot case 84A, in order from the axial bottom 151 side.

[0185] The retainer 600, the first valve member 601, the second valve member 602, the third valve member 603, the fourth valve member 604, the fifth valve member 605, and the retainer 606 are all made of metal. The retainer 600, the first valve member 601, the third valve member 603, the fourth valve member 604, and the fifth valve member 605 are all perforated flat plates of a certain thickness that can accommodate the mounting shaft portion 28 of the piston rod 21 on their inner side. The retainer 606 is an annular shape that can accommodate the mounting shaft portion 28 of the piston rod 21 on its inner side.

[0186] The retainer 600 has the same outer diameter as the retainer 83 of the first embodiment, but is thinner in the axial direction than the retainer 83. The pilot case 84A has a portion of the bottom 151 that is radially inner to the bottom 151, rather than the portion of the bottom 151 that is radially inner to the bottom 151, which is radially inner to the portion of the bottom 151 that is radially inner to the bottom 151, which is radially inner to the portion of the bottom 151 that is radially inner to the bottom 151.

[0187] The first valve member 601 has an outer diameter smaller than the inner diameter of the outer cylindrical portion 153 of the pilot case 84A. The first valve member 601 abuts against the retainer 600 and the seat portion 152A of the pilot case 84A. The first valve member 601 is flexible, and a passage hole 611 is formed in the portion radially between the portion abutting the retainer 600 and the portion abutting the seat portion 152A, passing through in the axial direction. The passage hole 611 communicates with the passage hole 161.

[0188] The second valve member 602 has a disc spring shape and includes a radially inward base portion 621 and a radially outward tapered plate portion 622. The base portion 621 is a perforated flat plate of a certain thickness that can accommodate the mounting shaft portion 28 of the piston rod 21 on its inner side. The tapered plate portion 622 extends radially outward from the outer peripheral edge of the base portion 621 and has a tapered cylindrical shape that moves further axially away from the base portion 621 the radially outward. The radius of the base portion 621 of the second valve member 602 is larger than the maximum distance between the radial center of the first valve member 601 and the passage hole 611. The outer diameter of the tapered plate portion 622 of the second valve member 602 is smaller than the inner diameter of the outer cylindrical portion 153 of the pilot case 84A. The second valve member 602 is oriented such that, in the axial direction, the tapered plate portion 622 is positioned opposite to the bottom portion 151 of the pilot case 84A relative to the base portion 621. The base portion 621 of the second valve member 602 abuts against the first valve member 601. The second valve member 602 has a passage hole 623 formed in the base portion 621 that penetrates axially. The passage hole 623 is radially aligned with the passage hole 611 of the first valve member 601 and is in constant communication with the passage hole 611. The tapered plate portion 622 of the second valve member 602 is flexible.

[0189] The third valve member 603 has a radius smaller than the minimum distance from the radial center of the second valve member 602 to the passage hole 623. The third valve member 603 contacts the base portion 621 of the second valve member 602 without blocking the passage hole 623. The third valve member 603 has a thickness thinner than the axial height of the second valve member 602.

[0190] The fourth valve member 604 has an outer diameter that is larger than the outer diameter of the second valve member 602 and smaller than the inner diameter of the outer cylindrical portion 153 of the pilot case 84A. The fourth valve member 604 is flexible. The fourth valve member 604 abuts against the third valve member 603 and also abuts against the outer peripheral edge of the tapered plate portion 622 of the second valve member 602. At this time, the fourth valve member 604 and the tapered plate portion 622 of the second valve member 602 undergo elastic deformation, and thus the fourth valve member 604 and the tapered plate portion 622 of the second valve member 602 are pressed together over their entire circumference. Specifically, the tapered plate portion 622 of the second valve member 602 undergoes elastic deformation in the direction that increases the taper, and the fourth valve member 604 undergoes elastic deformation such that it moves further away from the bottom portion 151 of the pilot case 84A in the axial direction as it moves towards the outer circumference. The fourth valve member 604 has a flow path hole 631 that penetrates axially in the portion between the radially adjacent portion that abuts the outer peripheral edge of the tapered plate portion 622 and the portion that abuts the third valve member 603.

[0191] The fifth valve member 605 has a radius greater than the maximum length connecting the radial center of the fourth valve member 604 and the flow path hole 631. The fifth valve member 605 is flexible. The fifth valve member 605 closes the flow path hole 631 by contacting the fourth valve member 604 with its entire circumference, including the outer circumference. At that time, the outer circumference of the fifth valve member 605 elastically deforms, and thus presses against the fourth valve member 604 over its entire circumference. Specifically, the fifth valve member 605 elastically deforms so that the outer circumference moves further away from the bottom 151 of the pilot case 84A in the axial direction. The outer circumference of the fifth valve member 605 separates from the fourth valve member 604, thereby opening the flow path hole 631.

[0192] The retainer 606 has an outer diameter smaller than the outer diameter of the fifth valve member 605. The radius of the retainer 606 is smaller than the minimum length from the radial center of the fourth valve member 604 to the flow hole 631. The notch 141 of the communication disk 78, which the retainer 606 abuts against, extends radially outward from the retainer 606.

[0193] The first valve member 601, the second valve member 602, the third valve member 603, the fourth valve member 604, and the fifth valve member 605 constitute a sub-valve 82A (first valve) which is positioned in contact with one axial seat portion 152A of the pilot case 84A. Therefore, the sub-valve 82A is formed by the first valve member 601, the second valve member 602, the third valve member 603, the fourth valve member 604, and the fifth valve member 605. In other words, the sub-valve 82A is formed by a plurality of first to fifth valve members 601 to 605.

[0194] The portion enclosed by the second valve member 602, the third valve member 603, the fourth valve member 604 that abuts against the second valve member 602, and the fifth valve member 605 that abuts against the fourth valve member 604 including its outer circumference forms the variable volume chamber 641 (second variable volume chamber). Therefore, the sub-valve 82A has a variable volume chamber 641. The variable volume chamber 641 communicates with the variable volume chamber 191 (see Figure 3) via the passage hole 623 of the second valve member 602 and the passage hole 611 of the first valve member 601. When the fourth valve member 604 abuts against the second valve member 602 and the flow path hole 631 of the fourth valve member 604 is closed by the fifth valve member 605, the variable volume chamber 641 and the variable volume chamber 191 are separated from the back pressure chamber 170. The volume of the variable-volume chamber 641 changes depending on the pressure between the back pressure chamber 170 and the variable-volume chamber 191 within the pilot case 84A.

[0195] When the pressure in the variable-volume chambers 641 and 191 (see Figure 3) becomes higher than the pressure in the back pressure chamber 170, the sub-valve 82A elastically deforms so that the radially outer portion of the fourth valve member 604, together with the radially outer portion of the fifth valve member 605, separates from the bottom 151 of the pilot case 84A. When the pressure in the variable-volume chambers 641 and 191 becomes higher than the pressure in the back pressure chamber 170 by a predetermined value or more, the fourth valve member 604 separates from the tapered plate portion 622 of the second valve member 602, allowing the oil L from the variable-volume chamber 641 to flow into the back pressure chamber 170. The sub-valve 82A constitutes a sub-valve mechanism 202A that controls the communication and blocking of the variable-volume chamber 641 and the back pressure chamber 170 by the opening and closing of the fourth valve member 604 and the tapered plate portion 622 of the second valve member 602. The sub-valve mechanism 202A generates a damping force when it opens and allows the oil liquid L from the variable volume chamber 641 to flow into the back pressure chamber 170.

[0196] When the pressure in the back pressure chamber 170 of the sub-valve 82A becomes higher than the pressure in the variable volume chambers 641 and 191 (see Figure 3), the outer circumference of the fourth valve member 604 elastically deforms, causing the tapered plate portion 622 of the second valve member 602 to elastically deform, and moving closer to the bottom 151 of the pilot case 84A. When the pressure in the back pressure chamber 170 of the sub-valve 82A becomes higher than the pressure in the variable volume chambers 641 and 191 by a predetermined value or more, the outer circumference of the fourth valve member 604 elastically deforms away from the fifth valve member 605, and the oil liquid L in the back pressure chamber 170 flows through the flow path hole 631 to the variable volume chambers 641 and 191. The sub-valve 82A comprises a fourth valve member 604 and a fifth valve member 605, which open and close to form a sub-valve mechanism 201A that controls communication and blocking between the back pressure chamber 170 and the variable volume chamber 641 and variable volume chamber 191. The sub-valve mechanism 201A generates a damping force when it opens to allow the oil liquid L from the back pressure chamber 170 to flow into the variable volume chamber 641.

[0197] The volume of the variable-volume chamber 641 changes when the sub-valve 82A deforms. When the pressure in the variable-volume chamber 641 and the variable-volume chamber 191 (see Figure 3) becomes higher than the pressure in the back pressure chamber 170, the fourth valve member 604 elastically deforms away from the bottom 151 of the pilot case 84A while maintaining contact with the second valve member 602, in other words, keeping the sub-valve mechanism 202A in a closed state, thereby increasing the volume of the variable-volume chamber 641 and decreasing the volume of the back pressure chamber 170.

[0198] When the pressure in the back pressure chamber 170 becomes higher than the pressure in the variable volume chambers 641 and 191 (see Figure 3), the fourth valve member 604 elastically deforms toward the bottom 151 of the pilot case 84A while maintaining contact with the fifth valve member 605, in other words, keeping the sub-valve mechanism 201A in a closed state, thereby increasing the volume of the back pressure chamber 170 and decreasing the volume of the variable volume chamber 641. The pilot case 84A, the sub-valve 82A, and the variable volume chamber 641 constitute the variable volume mechanism 651.

[0199] The passage within the piston passage portion 37 of the piston 18, the orifice 46 shown in Figure 2, the intermediate chamber 30 of the piston rod 21, the communication orifice 142 of the communication disk 78 shown in Figure 8, the back pressure chamber 170, the passage between the fifth valve member 605 and the fourth valve member 604 that occurs when the sub-valve mechanism 201A is opened, the passage of the flow path hole 631 of the fourth valve member 604, the variable volume chamber 641, the passage of the passage hole 623 of the second valve member 602, the passage of the passage hole 611 of the first valve member 601, the passage of the passage hole 161 of the pilot case 84A, the variable volume chamber 191 shown in Figure 3, and the passage between the hard valve 211 and the valve seat portion 156 that occurs when the hard valve mechanism 212 is opened constitute the extension-side second passage 215A through which the working fluid, oil liquid L, flows from one upper chamber 19 to the other lower chamber 20 as the piston 18 moves toward the extension side. The hard valve 211 operates to allow one-way flow of the oil liquid L from the upper chamber 19 to the lower chamber 20 through the second passage 215A. The variable volume chamber 192, the passage in the passage hole 185 of the valve disc 96, and the passage in the notch 197 of the valve disc 97 also constitute the second passage 215A. The second passage 215A runs parallel to the first passage 140 on the extension side, except for a portion on the upper chamber 19 side of the orifice 46 of the piston passage section 37, and connects the upper chamber 19 and the lower chamber 20. The sub-valve mechanism 201A restricts the flow of the oil liquid L from the upper chamber 19 to the lower chamber 20 through the second passage 215A when the piston 18 starts to move in the extension stroke. The variable volume chamber 641 of the variable volume mechanism 651 decreases in volume during the extension stroke before the sub-valve mechanism 201A opens, increasing the volume on the upper chamber 19 side.

[0200] The second passage 215A is provided with an orifice 46, a communication orifice 142, a back pressure chamber 170, a sub-valve mechanism 201A, a volume variable mechanism 651, a damping force variable mechanism 193, and a hard valve mechanism 212. The sub-valve mechanism 201A, the volume variable mechanism 651, the damping force variable mechanism 193, and the hard valve mechanism 212 are positioned in the second passage 215A where the flow of the oil liquid L is in series, and constitute a second damping force generating mechanism 216A that adjusts the flow of the oil liquid L moving within the second passage 215A.

[0201] The passage in the notch 197 of the valve disc 97, the passage in the passage hole 185 of the valve disc 96, the variable volume chamber 192, the passage between the variable valve 92 and the valve disc 96 that occurs when the valve mechanism 205 is opened, the variable volume chamber 191, the passage in the passage hole 161 of the pilot case 84A, the passage in the passage hole 611 of the first valve member 601, the passage in the passage hole 623 of the second valve member 602, the variable volume chamber 641, and the sub-valve mechanism The passage between the second valve member 602 and the fourth valve member 604 that is created when the valve of the structure 202A is opened, the back pressure chamber 170, the communication orifice 142 of the communication disk 78, the intermediate chamber 30 of the piston rod 21, the orifice 46 of the piston 18, and the passage within the piston passage portion 37 constitute the second passage 220A on the compression side, through which the working fluid, oil liquid L, flows from one lower chamber 20 to the other upper chamber 19 as the piston 18 moves toward the compression side. The second passage 220A is parallel to the first passage 60 on the compression side and connects the lower chamber 20 and the upper chamber 19. The second passage 220A is provided with a damping force variable mechanism 193, a volume variable mechanism 651, a sub-valve mechanism 202A, the back pressure chamber 170, the communication orifice 142, and the orifice 46. The second damping force generating mechanism 216A includes a damping force variable mechanism 193, a volume variable mechanism 651, and a sub-valve mechanism 202A, which are positioned in the second passage 220A so that the flow of oil L is in series, and adjust the flow of oil L in the second passage 220A. The sub-valve mechanism 202A restricts the flow of oil L from the lower chamber 20 to the upper chamber 19 through the second passage 220A when the piston 18 starts to move in the compression stroke. The volume variable chamber 641 of the volume variable mechanism 651 expands in volume before the sub-valve mechanism 202A opens in the compression stroke, increasing the volume on the lower chamber 20 side.

[0202] The third damping force generating mechanism 521, which generates damping force during the extension stroke, is provided separately from the sub-valve mechanism 201A and the hard valve mechanism 212, which generate damping force during the extension stroke of the second damping force generating mechanism 216A.

[0203] The extension-side first damping force generating mechanism 40, the extension-side sub-valve mechanism 201A of the second damping force generating mechanism 216A, and the extension-side third damping force generating mechanism 521 operate before the extension-side first damping force generating mechanism 40 and the extension-side sub-valve mechanism 201A of the second damping force generating mechanism 216A at a first piston speed, which is the axial movement speed of the piston 18. The extension-side sub-valve mechanism 201A of the second damping force generating mechanism 216A operates when the extension-side third damping force generating mechanism 521 is operating at a second piston speed that is faster than the first speed. The extension-side first damping force generating mechanism 40 operates when the extension-side third damping force generating mechanism 521 is operating and the extension-side sub-valve mechanism 201A of the second damping force generating mechanism 216A is operating at a third piston speed that is faster than the second speed.

[0204] The third damping force generating mechanism 511, which generates damping force during the compression stroke, is provided separately from the first damping force generating mechanism 42, which generates damping force during the compression stroke, and the valve mechanism 205 and sub-valve mechanism 202A, which generate damping force during the compression stroke of the second damping force generating mechanism 216A.

[0205] The compression-side first damping force generating mechanism 42, the compression-side valve mechanism 205 and sub-valve mechanism 202A of the second damping force generating mechanism 216A, and the compression-side third damping force generating mechanism 511 operate before the compression-side third damping force generating mechanism 511 at the 11th piston speed. Furthermore, the compression-side valve mechanism 205 and sub-valve mechanism 202A of the second damping force generating mechanism 216A operate when the piston speed is faster than the 11th speed, specifically when the compression-side third damping force generating mechanism 511 is operating. Furthermore, the compression-side first damping force generating mechanism 42 operates when the piston speed is faster than the 12th speed, the compression-side third damping force generating mechanism 511 is operating, and the compression-side valve mechanism 205 and sub-valve mechanism 202A of the second damping force generating mechanism 216A are operating.

[0206] As described above, the shock absorber 1A of the second embodiment includes an extension-side first damping force generating mechanism 40 provided in the extension-side first passage 140 to adjust the flow of oil liquid L moving within the first passage 140, a compression-side first damping force generating mechanism 42 provided in the compression-side first passage 60 to adjust the flow of oil liquid L moving within the first passage 60, and a second damping force generating mechanism provided in the second passages 215A and 220A arranged in parallel with the first passages 140 and 60 to adjust the flow of oil liquid L moving within the second passages 215A and 220A. The device includes a damping force generating mechanism 216A, an extension-side third damping force generating mechanism 521 provided in an extension-side third passage 520 arranged in parallel with the extension-side first passage 140 and the extension-side second passage 215A, which adjusts the flow of oil liquid L moving within the third passage 520, and a compression-side third damping force generating mechanism 511 provided in a compression-side third passage 510 arranged in parallel with the compression-side first passage 60 and the compression-side second passage 220A, which adjusts the flow of oil liquid L moving within the third passage 510.

[0207] Furthermore, the extension-side third damping force generating mechanism 521 operates before the extension-side first damping force generating mechanism 40 and the extension-side sub-valve mechanism 201A of the second damping force generating mechanism 216A when the piston speed, which is the axial movement speed of the piston 18 during the extension stroke, is a first speed. Also, the extension-side sub-valve mechanism 201A of the second damping force generating mechanism 216A operates when the extension-side third damping force generating mechanism 521 is operating at a second speed, which is faster than the first speed during the extension stroke. Furthermore, the extension-side first damping force generating mechanism 40 operates when the extension-side sub-valve mechanism 201A of the second damping force generating mechanism 216A is operating at a third speed, which is faster than the second speed during the extension stroke.

[0208] Furthermore, the compression-side third damping force generating mechanism 511 operates before the compression-side first damping force generating mechanism 42 and the compression-side valve mechanism 205 and compression-side sub-valve mechanism 202A of the second damping force generating mechanism 216A when the piston speed during the compression stroke is the 11th speed. Also, the valve mechanism 205 and sub-valve mechanism 202A of the compression-side second damping force generating mechanism 216A operate when the compression-side third damping force generating mechanism 511 operates when the piston speed during the compression stroke is faster than the 11th speed. Furthermore, the compression-side first damping force generating mechanism 42 operates when the compression-side valve mechanism 205 and sub-valve mechanism 202A of the second damping force generating mechanism 216A operate when the piston speed during the compression stroke is faster than the 12th speed.

[0209] The second damping force generating mechanism 216A includes a sub-valve 82A that adjusts the flow of oil L in the second passages 215A and 220A, and a hard valve 211, a variable valve 92, and a sub-valve 82A that partition the second passages 215A and 220A to form variable volume chambers 191, 192, and 641 capable of storing oil L, and which are operated by the oil L flowing due to the movement of the piston 18 to vary the volume of the variable volume chambers 191, 192, and 641. The sub-valve 82A, the hard valve 211, and the variable valve 92 are arranged in series within the second passages 215A and 220A. The second damping force generating mechanism 216A includes a pilot case 84A fixed to the piston rod 21 and forming part of the second passages 215A and 220A, a hard valve 211 positioned to contact the pilot case 84A and operating to allow one flow of the oil liquid L, and a variable valve 92 positioned inside the pilot case 84A and operating to allow the other flow of the oil liquid L, and contacting the hard valve 211 to form a variable volume chamber 192 between itself and the hard valve 211.

[0210] The second damping force generating mechanism 216A includes a pilot case 84A fixed to the piston rod 21 and forming part of the second passages 215A and 220A, a sub-valve 82A positioned in contact with one axial side of the pilot case 84A and adjusting the flow of oil L in the second passages 215A and 220A, a hard valve 211 positioned in contact with the other axial side of the pilot case 84A and adjusting the flow of oil L in the second passage 215A, and a variable valve 92 provided between the pilot case 84A and the hard valve 211, forming a variable volume chamber 192 between itself and the hard valve 211 by contacting it, and opening and closing with the flow of oil L. The third damping force generating mechanism 511 includes a seat member 406 fixed to the piston rod 21 and forming part of the third passage 510, and a valve member 407 that contacts the seat member 406 and opens when separated from the seat member 406 by the flow of oil L. The third damping force generating mechanism 521 is fixed to the piston rod 21 and includes a seat member 406 in which a part of the third passage 520 is formed, and a valve member 403 that contacts the seat member 406 and opens when separated from the seat member 406 by the flow of oil liquid L.

[0211] The second damping force generating mechanism 216A includes a pilot case 84A fixed to the piston rod 21 and forming part of the second passages 215A and 220A; a sub-valve 82A (first valve) positioned in contact with one axial side of the pilot case 84A and adjusting the flow of oil L in the second passages 215A and 220A; a hard valve 211 positioned in contact with the other axial side of the pilot case 84A and adjusting the flow of oil L in the second passages 215A and 220A; and a variable valve 92 provided between the pilot case 84A and the hard valve 211, which contacts the hard valve 211 to form a variable volume chamber 192 (first variable volume chamber) between itself and the hard valve 211, and opens and closes according to the flow of oil L. The sub-valve 82A is formed by a plurality of valve members: a first valve member 601, a second valve member 602, a third valve member 603, a fourth valve member 604, and a fifth valve member 605. The sub-valve 82A includes a volume-variable chamber 641 (second volume-variable chamber) whose volume changes according to the pressure in the pilot case 84A, and sub-valve mechanisms 201A and 202A (valve mechanisms) that control the oil liquid L in the volume-variable chamber 641.

[0212] The sub-valve 82A (first valve) is formed by a first valve member 601 that contacts the pilot case 84A, a second valve member 602 that contacts the first valve member 601, a third valve member 603 that contacts the second valve member 602, a fourth valve member 604 that contacts the second valve member 602 and the third valve member 603, and a fifth valve member 605 that contacts the fourth valve member 604.

[0213] The fourth valve member 604 is provided with a flow path hole 631 located inside the outer circumference of the fifth valve member 605, which allows communication between the back pressure chamber 170 in the pilot case 84A and the variable volume chamber 641 (second variable volume chamber). The flow path hole 631 opens and closes as the fifth valve member 605 operates.

[0214] The configuration described above is shown in the hydraulic circuit diagram in Figure 9. As shown in Figure 9, a first passage 140 is provided connecting the upper chamber 19 and the lower chamber 20. A first damping force generating mechanism 40 is provided in the first passage 140, and a fixed orifice 132 is provided in parallel with the first damping force generating mechanism 40. Also, in parallel with the first passage 140, second passages 215A and 220A are provided connecting the upper chamber 19 and the lower chamber 20. Common to the second passages 215A and 220A, from the upper chamber 19 side in order, are an orifice 46, an intermediate chamber 30, a communication orifice 142, and a back pressure chamber 170. The back pressure chamber 170 controls the opening of the valve of the first damping force generating mechanism 40 with its pressure. On the side of the back pressure chamber 170 opposite the communication orifice 142, the second passage 215A and the second passage 220A are separated, with a sub-valve mechanism 201A provided in the second passage 215A and a sub-valve mechanism 202A provided in the second passage 220A. In parallel with the sub-valve mechanisms 201A and 202A, a volume variable mechanism 651 is provided in common to the second passages 215A and 220A, and the volume variable chamber 641 of the volume variable mechanism 651 on the side opposite the back pressure chamber 170 is in communication with the volume variable chamber 191 of the damping force variable mechanism 193. The second passage 215A has a flow path that connects the volume variable chamber 192 of the damping force variable mechanism 193 to the lower chamber 20, and a flow path that connects the volume variable chamber 191 to the lower chamber 20 via the hard valve mechanism 212. The second passage 220A shares a flow path with the second passage 215A that connects the variable volume chamber 192 to the lower chamber 20, and has a flow path that allows oil liquid L to flow from the lower chamber 20 to the variable volume chamber 191 via the valve mechanism 205. A first passage 60 is provided connecting the lower chamber 20 and the upper chamber 19, and a first damping force generating mechanism 42 is provided in the first passage 60. Third passages 510 and 520 are provided connecting the lower chamber 20 and the intermediate chamber 30, with a third damping force generating mechanism 511 provided in the third passage 510 and a third damping force generating mechanism 521 provided in the third passage 520. An orifice 484 is provided on the upper chamber 19 side of the third damping force generating mechanism 511 and the third damping force generating mechanism 521, and is common to the third passages 510 and 520.

[0215] In the shock absorber 1 of the first embodiment described above, the extension-side sub-valve mechanism 201 of the second damping force generating mechanism 216 has a higher opening pressure than the extension-side third damping force generating mechanism 521, and when closed, it completely closes to stop the flow of oil L in the second passage 215. Also, the compression-side sub-valve mechanism 202 of the second damping force generating mechanism 216 has a higher opening pressure than the compression-side third damping force generating mechanism 511, and when closed, it completely closes to stop the flow of oil L in the second passage 220. For this reason, when the third damping force generating mechanisms 511 and 521 open, the hydraulic pressure changes rapidly, causing a large rod acceleration in the piston rod 21, which may result in the generation of abnormal noise.

[0216] In contrast, according to the buffer 1A of the second embodiment, the second damping force generating mechanism 216A has a sub-valve 82A (first valve) that adjusts the flow of oil liquid L in the second passages 215A and 220A, which is formed by a plurality of valve members: a first valve member 601, a second valve member 602, a third valve member 603, a fourth valve member 604, and a fifth valve member 605. It also has a volume variable chamber 641 (second volume variable chamber) whose volume changes according to the pressure in the pilot case 84A, and sub-valve mechanisms 201A and 202A (valve mechanisms) that control the oil liquid L in the volume variable chamber 641. Therefore, when the third damping force generating mechanisms 511 and 521, which are opened when the sub-valve mechanisms 201A and 202A are closed, are opened, the volume variable chamber 641 changes the volume of the upper chamber 19 and the lower chamber 20 in accordance with the pressure change, thereby suppressing abrupt changes in hydraulic pressure. Therefore, it is possible to suppress the increase in rod acceleration of the piston rod 21 caused by a sudden change in hydraulic pressure, and as a result, the generation of abnormal noise can be suppressed.

[0217] Furthermore, according to the buffer 1A of the second embodiment, the sub-valve 82A (first valve) is formed by a first valve member 601 that abuts against the pilot case 84A, a second valve member 602 that abuts against the first valve member 601, a third valve member 603 that abuts against the second valve member 602, a fourth valve member 604 that abuts against the second valve member 602 and the third valve member 603, and a fifth valve member 605 that abuts against the fourth valve member 604. Therefore, a sub-valve 82A having a variable volume chamber 641 and sub-valve mechanisms 201A and 202A can be realized with a simple configuration.

[0218] Furthermore, according to the buffer 1A of the second embodiment, the fourth valve member 604 is provided with a flow path hole 631 located inside the outer circumference of the fifth valve member 605, which allows communication between the back pressure chamber 170 in the pilot case 84A and the variable volume chamber 641 (second variable volume chamber). The flow path hole 631 opens and closes with the operation of the fifth valve member 605. Therefore, communication and disconnection between the back pressure chamber 170 and the variable volume chamber 641 can be controlled with a simple configuration.

[0219] According to the above-described embodiment of the present disclosure, it is possible to provide a shock absorber that can generate damping force more effectively.

[0220] 1, 1A... Shock absorber, 2... Cylinder, 18... Piston, 19... Upper chamber (first chamber), 20... Lower chamber (second chamber), 21... Piston rod, 40, 42... First damping force generating mechanism, 60, 140... First passage, 82, 82A... Sub-valve (valve member, first valve), 84, 84A... Pilot case (case member), 92... Variable valve (partition member), 166... ​​Outer circumference valve section, 167... Inner circumference valve section, 191, 192, 641... Volume variable chamber, 211... Hard valve (partition member, second valve), 215, 215A, 220, 220A... Second passage, 216, 216A... Second damping force generating mechanism, 201A, 202A... Sub-valve mechanism (valve mechanism), 403, 407... Valve member (third valve), 406... Seat member, 510, 520... Third passage, 511, 521... Third damping force generating mechanism, 601... First valve member, 602... Second valve member, 603... Third valve member, 604... Fourth valve member, 605... Fifth valve member, 631... Flow hole, L... Oil (working fluid).

Claims

1. A cylinder in which a working fluid is sealed; a piston movably provided within the cylinder and dividing the inside of the cylinder into a first chamber and a second chamber; a piston rod connected to the piston and extending to the outside of the cylinder; a first damping force generating mechanism provided in a first passage through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the first passage; a second damping force generating mechanism provided in a second passage arranged in parallel with the first passage through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the second passage; a third damping force generating mechanism provided in a third passage arranged in parallel with the first and second passages through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the third passage. A shock absorber wherein the third damping force generating mechanism operates before the first damping force generating mechanism and the second damping force generating mechanism when the piston is moving at a first speed, the second damping force generating mechanism operates when the third damping force generating mechanism is operating when the piston is moving at a second speed faster than the first speed, and the first damping force generating mechanism operates when the second damping force generating mechanism is operating when the piston is moving at a third speed faster than the second speed.

2. A shock absorber according to claim 1, wherein the second damping force generating mechanism comprises a valve member that adjusts the flow of the working fluid in the second passage, and a partitioning member that partitions the second passage to form a variable-volume chamber capable of storing the working fluid, and is operated by the working fluid flowing by the movement of the piston to vary the volume of the variable-volume chamber.

3. A buffer according to claim 2, wherein the valve member and the partition member are arranged in series within the second passage.

4. A buffer according to claim 2 or 3, wherein the valve member is an annular first valve having an outer circumferential valve portion that allows one flow of the working fluid and an inner circumferential valve portion that allows the other flow of the working fluid.

5. A shock absorber according to claim 2 or 3, wherein the second damping force generating mechanism has a case member fixed to the piston rod and forming a part of the second passage, and the partition member comprises a second valve disposed to contact the case member and operating to allow one flow of the working fluid, and a variable valve disposed within the case member and operating to allow the other flow of the working fluid, and contacting the second valve to form the variable volume chamber between itself and the second valve.

6. The device comprises: a cylinder in which a working fluid is sealed; a piston movably provided within the cylinder and dividing the cylinder into a first chamber and a second chamber; a piston rod connected to the piston and extending to the outside of the cylinder; a first damping force generating mechanism provided in a first passage through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the first passage; a second damping force generating mechanism provided in a second passage arranged in parallel with the first passage through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the second passage; and a third damping force generating mechanism provided in a third passage arranged in parallel with the first and second passages through which the working fluid flows as a result of the movement of the piston, and for adjusting the flow of the working fluid moving within the third passage. The second damping force generating mechanism comprises a case member fixed to the piston rod and having a part of the second passage formed therein; a first valve positioned in contact with one axial direction of the case member and adjusting the flow of the working fluid in the second passage; a second valve positioned in contact with the other axial direction of the case member and adjusting the flow of the working fluid in the second passage; and a variable valve provided between the case member and the second valve, which contacts the second valve to form a variable volume chamber between itself and the second valve and opens and closes according to the flow of the working fluid. The third damping force generating mechanism comprises a seat member fixed to the piston rod and having a part of the third passage formed therein; and a third valve that contacts the seat member and opens when separated from the seat member by the flow of the working fluid.

7. A cylinder in which a working fluid is sealed; a piston movably provided within the cylinder and dividing the inside of the cylinder into a first chamber and a second chamber; a piston rod connected to the piston and extending to the outside of the cylinder; a first damping force generating mechanism provided in a first passage through which the working fluid flows as the piston moves, and which adjusts the flow of the working fluid moving within the first passage; a second damping force generating mechanism provided in a second passage arranged in parallel with the first passage through which the working fluid flows as the piston moves, and which adjusts the flow of the working fluid moving within the second passage; a third damping force generating mechanism provided in a third passage arranged in parallel with the first and second passages through which the working fluid flows as the piston moves, and which adjusts the flow of the working fluid moving within the third passage. The second damping force generating mechanism includes a case member fixed to the piston rod and forming a part of the second passage, a first valve positioned in contact with one axial direction of the case member and adjusting the flow of the working fluid in the second passage, a second valve positioned in contact with the other axial direction of the case member and adjusting the flow of the working fluid in the second passage, and a variable valve provided between the case member and the second valve, which contacts the second valve to form a first variable volume chamber between itself and the second valve and opens and closes according to the flow of the working fluid, wherein the first valve is formed by a plurality of valve members and includes a second variable volume chamber whose volume changes according to the pressure in the case member, and a valve mechanism for controlling the working fluid in the second variable volume chamber.

8. The shock absorber according to claim 7, wherein the first valve is formed by a first valve member in contact with the case member, a second valve member in contact with the first valve member, a third valve member in contact with the second valve member, a fourth valve member in contact with the second valve member and the third valve member, and a fifth valve member in contact with the fourth valve member.

9. A buffer according to claim 8, wherein the fourth valve member is provided with a flow path hole that allows communication between the inside of the case member and the second variable volume chamber, located inside the outer circumference of the fifth valve member, and the flow path hole opens and closes when the fifth valve member is operated.

Images