Shock absorber

Abstract

To provide a shock absorber capable of improving durability.SOLUTION: A shock absorber includes: a first damping force generation mechanism 146 which is provided in a first passage 145 and is valve-opened when working fluid L moves from a first chamber 23 to a second chamber 22; a second damping force generation mechanism 153 which is provided in a second passage 152 and is valve-opened when the working fluid L moves from the second chamber 22 to the first chamber 23; a first valve mechanism 148 which is provided in the first passage 145, is disposed closer to the first chamber 23 than the first damping force generation mechanism 146, and is valve-opened when the working fluid L moves from the first chamber 23 to the second chamber 22; a third passage 161 which is connected between the second chamber 22 and the second damping force generation mechanism 153 in the second passage 152 and between the first damping force generation mechanism 146 and the first valve mechanism 148 in the first passage 145; and a second valve mechanism 162 which is provided in the third passage 161 and is valve-opened when the working fluid L moves from the second passage 152 to the first passage 145.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] A shock absorber is provided with a damping force generating mechanism that generates a damping force during an extension stroke in which a rod extends from a cylinder, and a damping force generating mechanism that generates a damping force during a compression stroke in which the rod enters the cylinder (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a shock absorber, it is required to improve durability.

[0005] Therefore, an object of the present invention is to provide a shock absorber capable of improving durability.

Means for Solving the Problems

[0006] To achieve the above object, a first aspect of the present invention includes a cylinder, a working fluid provided in the cylinder, a piston provided in the cylinder and partitioning the inside of the cylinder into a first chamber and a second chamber, a piston rod having a first end connected to the piston and a second end extending from the cylinder, a first passage and a second passage provided in the piston and communicating the first chamber and the second chamber, a first damping force generating mechanism provided in the first passage and opening a valve when the working fluid moves from the first chamber to the second chamber, a second damping force generating mechanism provided in the second passage and opening a valve when the working fluid moves from the second chamber to the first chamber, a first valve mechanism provided in the first passage and disposed on the first chamber side of the first damping force generating mechanism and opening a valve when the working fluid moves from the first chamber to the second chamber, a third passage connected between the second chamber and the second damping force generating mechanism in the second passage and between the first damping force generating mechanism and the first valve mechanism in the first passage and communicating the second passage and the first passage, and a second valve mechanism provided in the third passage and opening a valve when the working fluid moves from the second passage to the first passage.

[0007] A second aspect of the present invention includes a cylinder, a working fluid provided in the cylinder, a piston provided in the cylinder and partitioning the inside of the cylinder into a first chamber and a second chamber, a piston rod having a first end connected to the piston and a second end extending from the cylinder, a first passage and a second passage provided in the piston and communicating the first chamber and the second chamber, a first damping force generating mechanism provided in the first passage and opening a valve when the working fluid moves from the first chamber to the second chamber, a second damping force generating mechanism provided in the second passage and opening a valve when the working fluid moves from the second chamber to the first chamber, a first valve mechanism provided in the first passage and disposed closer to the first chamber side than the first damping force generating mechanism and opening a valve when the working fluid moves from the first chamber to the second chamber, and a fourth passage provided in parallel with the first passage and communicating the second chamber with a portion between the first damping force generating mechanism and the first valve mechanism in the first passage, wherein at least a part of the fourth passage includes a first orifice portion that suppresses the flow rate of the working fluid more than the first passage.

Advantages of the Invention

[0008] According to the present invention, it is possible to improve durability.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Embodiments will be described with reference to the drawings. In the following description, for convenience of explanation, the upper side in FIGS. 1 and 2 is referred to as "upper", and the lower side in FIGS. 1 and 2 is referred to as "lower".

[0011] The shock absorber 1 of the embodiment shown in FIG. 1 is a shock absorber used for a suspension device of a railway vehicle, a two-wheeled or four-wheeled automobile, etc. Specifically, the shock absorber 1 is a shock absorber used for a suspension device of a four-wheeled automobile. As shown in FIG. 1, the shock absorber 1 is a double-tube type shock absorber including a cylinder 4 having an inner tube 2 and an outer tube 3. The inner tube 2 is cylindrical. The outer tube 3 is a bottomed cylindrical shape having a larger diameter than the inner tube 2. The outer tube 3 is provided coaxially with the inner tube 2 on the radially outer side of the inner tube 2. The space between the outer tube 3 and the inner tube 2 forms a reservoir chamber 5.

[0012] The outer tube 3 has a tube portion 8 and a bottom portion 9. The tube portion 8 is cylindrical. The bottom portion 9 closes one axial end portion of the tube portion 8. The side opposite to the bottom portion 9 of the tube portion 8 is an opening. A mounting eye 10 is fixed to the side opposite to the tube portion 8 in the axial direction of the bottom portion 9.

[0013] The shock absorber 1 includes a valve body 12 and a rod guide 13. The valve body 12 is annular and is provided on the bottom portion 9 side in the axial direction of the inner tube 2 and the outer tube 3. The rod guide 13 is annular and is provided on the side opposite to the bottom portion 9 in the axial direction of the inner tube 2 and the outer tube 3. The valve body 12 constitutes a base valve 15. The outer peripheral portion of the valve body 12 has a stepped shape, and is placed on the bottom portion 9 in a state of being positioned radially in the tube portion 8 at its large-diameter portion. The outer peripheral portion of the rod guide 13 also has a stepped shape, and its large-diameter portion is positioned radially in the tube portion 8 and fitted.

[0014] The inner cylinder 2 has one axial end fitted to the small-diameter portion of the outer peripheral portion of the valve body 12. One axial end of the inner cylinder 2 is engaged with the bottom portion 9 of the outer cylinder 3 via this valve body 12. Also, the other axial end of the inner cylinder 2 is fitted to the small-diameter portion of the outer peripheral portion of the rod guide 13. The other axial end of the inner cylinder 2 is engaged with the cylindrical portion 8 of the outer cylinder 3 via this rod guide 13. In this state, the inner cylinder 2 is positioned radially with respect to the outer cylinder 3. Here, between the valve body 12 and the bottom portion 9 communicates with the space between the inner cylinder 2 and the outer cylinder 3. Therefore, between the valve body 12 and the bottom portion 9, like the space between the inner cylinder 2 and the outer cylinder 3, constitutes the reservoir chamber 5.

[0015] The shock absorber 1 includes a seal member 18. The seal member 18 is provided on the side opposite to the bottom portion 9 of the rod guide 13. This seal member 18 is also fitted to the inner peripheral portion of the cylindrical portion 8 in the same manner as the rod guide 13. A locking portion 19 is formed at the end of the cylindrical portion 8 opposite to the bottom portion 9. The locking portion 19 is formed by plastically deforming the cylindrical portion 8 radially inward by caulking such as curling. The seal member 18 is sandwiched between this locking portion 19 and the rod guide 13. The seal member 18 closes the opening of the outer cylinder 3 and is specifically an oil seal.

[0016] The shock absorber 1 includes a piston 21. The piston 21 is slidably provided in the cylinder 4. Specifically, the piston 21 is slidably provided in the inner cylinder 2 of the cylinder 4. The piston 21 divides the inside of the inner cylinder 2 into two chambers, an upper chamber 22 (second chamber) and a lower chamber 23 (first chamber). The upper chamber 22 is provided between the piston 21 and the rod guide 13 inside the inner cylinder 2. The lower chamber 23 is provided between the piston 21 and the valve body 12 inside the inner cylinder 2. The lower chamber 23 is defined by the valve body 12 and the reservoir chamber 5. In the cylinder 4, hydraulic fluid L, which is a working fluid, is enclosed in the upper chamber 22 and the lower chamber 23. In the cylinder 4, gas G, which is a working fluid, and hydraulic fluid L are enclosed in the reservoir chamber 5. Therefore, the shock absorber 1 is a hydraulic shock absorber in which hydraulic fluid L, which is a working fluid, is provided in the cylinder 4.

[0017] The shock absorber 1 includes a piston rod 31 which is a rod-shaped shaft member. One end side in the axial direction of the piston rod 31 is disposed inside the cylinder 4 and is connected and fixed to the piston 21. The other end side in the axial direction of the piston rod 31 extends outside from the cylinder 4. The piston rod 31 is made of metal and penetrates through the upper chamber 22. The piston rod 31 does not penetrate through the lower chamber 23. Therefore, the upper chamber 22 is a rod-side chamber through which the piston rod 31 penetrates. The lower chamber 23 is a bottom-side chamber on the bottom 9 side of the cylinder 4.

[0018] The piston 21 and the piston rod 31 move integrally. In the extension stroke of the shock absorber 1 where the protruding amount of the piston rod 31 from the cylinder 4 increases, in other words, the shock absorber 1 extends out from the cylinder 4, the piston 21 moves toward the upper chamber 22 side. In the compression stroke of the shock absorber 1 where the protruding amount of the piston rod 31 from the cylinder 4 decreases, in other words, the shock absorber 1 enters the cylinder 4, the piston 21 moves toward the lower chamber 23 side.

[0019] Both the rod guide 13 and the seal member 18 are annular. The piston rod 31 is slidably inserted inside each of these rod guide 13 and seal member 18 and extends from the inside of the cylinder 4 to the outside. One end side portion in the axial direction of the piston rod 31 is fixed to the piston 21 inside the cylinder 4. The other end side portion in the axial direction of the piston rod 31 extends outside the cylinder 4 via the rod guide 13 and the seal member 18.

[0020] The rod guide 13 supports the piston rod 31 with respect to the cylinder 4 so as to be movable in its axial direction while restricting its radial movement. The outer peripheral portion of the seal member 18 is in close contact with the outer cylinder 3 of the cylinder 4. The inner peripheral portion of the seal member 18 is in sliding contact with the outer peripheral portion of the piston rod 31 that moves in the axial direction. Thereby, the seal member 18 prevents the oil fluid L and the gas G inside the cylinder 4 from leaking to the outside.

[0021] The piston rod 31 has a main shaft portion 32, a mounting shaft portion 33, and a threaded shaft portion 34. The mounting shaft portion 33 and the threaded shaft portion 34 have smaller diameters than the main shaft portion 32. The mounting shaft portion 33 extends from the main shaft portion 32, and the threaded shaft portion 34 is provided on the side opposite to the main shaft portion 32 in the axial direction of the mounting shaft portion 33. In the piston rod 31, the main shaft portion 32 is slidably fitted to the rod guide 13 and the seal member 18. In the piston rod 31, the mounting shaft portion 33 and the threaded shaft portion 34 are disposed in the cylinder 4 and connected to the piston 21 or the like. The end portion of the main shaft portion 32 on the mounting shaft portion 33 side extends in the direction perpendicular to the axis. The main shaft portion 32 and the mounting shaft portion 33 are cylindrical. On the threaded shaft portion 34, a male thread 35 is formed on the outer side in the radial direction.

[0022] In the shock absorber 1, for example, the protruding portion of the main shaft portion 32 of the piston rod 31 from the cylinder 4 is disposed at the upper part in the vertical direction and supported by the vehicle body. At that time, in the shock absorber 1, the mounting eye 10 fixed to the bottom portion 9 of the cylinder 4 is disposed at the lower part in the vertical direction and connected to the wheel side. When the shock absorber 1 is of the single-tube type, conversely, it is also possible to configure such that the cylinder 4 side is supported by the vehicle body and the piston rod 31 is connected to the wheel side.

[0023] As shown in FIG. 2, the piston 21 is composed of a metal piston body 61 fitted and connected to the mounting shaft portion 33 of the piston rod 31, and an annular friction member 62 integrally mounted on the outer peripheral surface of the piston body 61 and sliding in the inner cylinder 2.

[0024] The piston body 61 is disc-shaped, and in the center in the radial direction, in order from the side opposite to the main shaft portion 32 in the axial direction, a rod fitting hole 71, a sleeve fitting hole 72, an intermediate hole 73, a guide hole 74, and an opening hole 75 are formed. The rod fitting hole 71, the sleeve fitting hole 72, the intermediate hole 73, the guide hole 74, and the opening hole 75 all have their central axes aligned, and thus are all formed coaxially.

[0025] The rod fitting hole 71 has a smaller inner diameter than any of the sleeve fitting hole 72, the intermediate hole 73, the guide hole 74, and the opening hole 75. The rod fitting hole 71 is a straight hole, and the mounting shaft portion 33 of the piston rod 31 fits inside thereof.

[0026] The sleeve fitting hole 72 is a straight hole and has a larger inner diameter than the inner diameter of the rod fitting hole 71.

[0027] The intermediate hole 73 is tapered and has a minimum inner diameter larger than the inner diameter of the sleeve fitting hole 72. The inner diameter of the intermediate hole 73 becomes smaller as it approaches the sleeve fitting hole 72 in the axial direction.

[0028] The guide hole 74 is a straight hole and has an inner diameter larger than the maximum inner diameter of the intermediate hole 73.

[0029] The opening hole 75 extends in a direction opposite to the intermediate hole 73 from the end portion on the side opposite to the intermediate hole 73 in the axial direction of the guide hole 74. The opening hole 75 is tapered, and its inner diameter becomes larger as it moves away from the guide hole 74 in the axial direction.

[0030] On the piston body 61, the portion outside the opening hole 75 side in the radial direction forms a first valve seat portion 81 that extends in a direction perpendicular to the axis of the piston body 61. The first valve seat portion 81 is provided at one end portion of the piston body 61 in the axial direction, is outside the opening hole 75 side in the radial direction of the piston body 61, and forms an annular shape coaxial with the opening hole 75.

[0031] On the piston body 61, a second valve seat portion 82 and an inner seat portion 83 are provided at the end portion on the side opposite to the first valve seat portion 81 in the axial direction.

[0032] The inner seat portion 83 is outside the rod fitting hole 71 side in the radial direction of the piston body 61, extends in a direction perpendicular to the axis of the piston body 61, and forms an annular shape coaxial with the rod fitting hole 71. The inner side in the radial direction of the inner seat portion 83 is a part of the rod fitting hole 71.

[0033] The second valve seat portion 82 is located outside the inner seat portion 83 in the radial direction of the piston body 61 and extends in the direction perpendicular to the axis of the piston body 61, forming an annular shape coaxial with the inner seat portion 83. Between the second valve seat portion 82 and the inner seat portion 83 of the piston body 61, there is a passage recess 84 that is recessed in the direction of the first valve seat portion 81 from the end face on the side opposite to the first valve seat portion 81 of the second valve seat portion 82 and the inner seat portion 83 in the axial direction of the piston body 61. The passage recess 84 has an annular shape coaxial with the second valve seat portion 82 and the inner seat portion 83.

[0034] Between the sleeve fitting hole 72 and the intermediate hole 73 of the piston body 61 in its radial and axial directions, there is a first intermediate valve seat portion 86. The first intermediate valve seat portion 86 extends in the direction perpendicular to the axis of the piston body 61 and has an annular shape coaxial with the sleeve fitting hole 72 and the intermediate hole 73. At the intermediate position in its radial direction, a passage groove 87 is formed in the first intermediate valve seat portion 86 in the axial direction of the piston body 61, which is recessed in the direction of the second valve seat portion 82 and the inner seat portion 83 from the end face on the side opposite to the second valve seat portion 82 and the inner seat portion 83 of the first intermediate valve seat portion 86. The passage groove 87 has an annular shape coaxial with the first intermediate valve seat portion 86.

[0035] Between the intermediate hole 73 and the guide hole 74 of the piston body 61 in its radial and axial directions, there is a second intermediate valve seat portion 88. The second intermediate valve seat portion 88 extends in the direction perpendicular to the axis of the piston body 61 and has an annular shape coaxial with the intermediate hole 73 and the guide hole 74. At the intermediate position in its radial direction, a passage groove 89 is formed in the second intermediate valve seat portion 88 in the axial direction of the piston body 61, which is recessed in the direction of the second valve seat portion 82 and the inner seat portion 83 from the end face on the side opposite to the second valve seat portion 82 and the inner seat portion 83 of the second intermediate valve seat portion 88. The passage groove 89 has an annular shape coaxial with the second intermediate valve seat portion 88.

[0036] In the piston body 61, a passage hole 91 is formed such that one end opens into the passage groove 87 of the first intermediate valve seat portion 86, and the other end opens outside the second valve seat portion 82 in the radial direction of the piston body 61. A plurality of passage holes 91 are formed in the piston body 61 at intervals in the circumferential direction of the piston body 61, and these passage holes 91 communicate with each other through the passage groove 87. The passage hole 91 is always in communication with the lower chamber 23.

[0037] In the piston body 61, a passage hole 94 is formed such that one end opens into the passage recess 84, and the other end opens outside the first valve seat portion 81 in the radial direction of the piston body 61. A plurality of passage holes 94 are formed in the piston body 61 at intervals in the circumferential direction of the piston body 61, and these passage holes 94 communicate with each other through the passage recess 84. The passage hole 94 is always in communication with the upper chamber 22.

[0038] In the piston body 61, a passage hole 97 is formed such that one end opens into the passage groove 89 of the second intermediate valve seat portion 88, and the other end opens at an intermediate position of the corresponding passage hole 94. A plurality of passage holes 97 are formed in the piston body 61 at intervals in the circumferential direction of the piston body 61, and these passage holes 97 communicate with each other through the passage groove 89. Each of these passage holes 97 communicates with a corresponding one of the plurality of passage holes 94. These passage holes 97 are always in communication with the upper chamber 22.

[0039] On the mounting shaft portion 33 of the piston rod 31, between the main shaft portion 32 and the first valve seat portion 81 of the piston 21, in order from the piston 21 side in the axial direction, one disk 101, a plurality of disks 102, one disk 103, one disk 104, and one annular member 105 are provided. The disks 101 to 104 and the annular member 105 are all made of metal and are perforated circular flat plates, and all have the mounting shaft portion 33 fitted inside.

[0040] The disk 101 has an outer diameter larger than the outer diameter of the first valve seat portion 81 of the piston 21. The disk 101 can be seated and separated from the first valve seat portion 81. The disk 101 is formed with a notch 107 on the outer peripheral side for communicating the inside and outside in the radial direction of the first valve seat portion 81 even when seated on the first valve seat portion 81.

[0041] The plurality of disks 102 have an outer diameter equivalent to the outer diameter of the disk 101.

[0042] The disk 103 has an outer diameter smaller than the outer diameter of the disk 102 and smaller than the outer diameter of the end face on the mounting shaft portion 33 side in the axial direction of the main shaft portion 32 of the piston rod 31.

[0043] The disk 104 has an outer diameter larger than the outer diameter of the disk 103.

[0044] The annular member 105 has an outer diameter smaller than the outer diameter of the disk 104 and larger than the outer diameter of the end portion on the mounting shaft portion 33 side in the axial direction of the main shaft portion 32 of the piston rod 31. The annular member 105 is thicker and has higher rigidity than the disks 101 and 102, and is in contact with the end portion on the mounting shaft portion 33 side in the axial direction of the main shaft portion 32.

[0045] On the mounting shaft portion 33 of the piston rod 31, on the side opposite to the main shaft portion 32 of the piston 21, in order from the piston 21 side in the axial direction, one disk 111, a plurality of disks 112, one disk 113, one disk 114, one disk 115, and one annular member 116 are provided. The disks 111 to 115 and the annular member 116 are all made of metal and are perforated circular flat plates, and all have the mounting shaft portion 33 fitted inside.

[0046] The disk 111 has an outer diameter larger than the outer diameter of the second valve seat portion 82 of the piston 21. The disk 111 can be seated on and detached from the second valve seat portion 82. The disk 111 is formed with a notch portion 117 on the outer peripheral side that communicates the inside and outside in the radial direction of the second valve seat portion 82 even when seated on the second valve seat portion 82.

[0047] The plurality of disks 112 have an outer diameter equal to the outer diameter of the disk 111.

[0048] The disk 113 has an outer diameter smaller than the outer diameter of the disk 112.

[0049] The disk 114 has an outer diameter smaller than the outer diameter of the disk 113.

[0050] The disk 115 has an outer diameter smaller than the outer diameter of the disk 113 and larger than the outer diameter of the disk 114.

[0051] The annular member 116 has an outer diameter smaller than the outer diameter of the disk 115 and larger than the outer diameter of the disk 114. The annular member 116 is thicker and has higher rigidity than the disks 111 to 113.

[0052] Inside the piston 21, a first sleeve 121, a first spring member 122, a second sleeve 123, a second spring member 124, a first intermediate valve disk 125, and a second intermediate valve disk 126 are provided. The first sleeve 121, the first spring member 122, the second sleeve 123, the second spring member 124, the first intermediate valve disk 125, and the second intermediate valve disk 126 are all made of metal.

[0053] The first sleeve 121 is cylindrical and has a mounting shaft portion 33 fitted to the inner side in the radial direction. The outer side in the radial direction of the first sleeve 121 is fitted to the sleeve fitting hole 72 of the piston 21.

[0054] The first intermediate valve disk 125 is in the shape of a perforated disk, and the first sleeve 121 is arranged on the inner side in the radial direction thereof. The first intermediate valve disk 125 is guided by the outer peripheral surface of the first sleeve 121 on the inner side in the radial direction and moves in the axial direction of the first sleeve 121. The first intermediate valve disk 125 seats on the first intermediate valve seat portion 86 and closes the passage groove 87. When the first intermediate valve disk 125 disengages from the first intermediate valve seat portion 86, the passage groove 87 is opened.

[0055] As shown in FIG. 3, the first spring member 122 has a perforated disk-shaped main body portion 131 and spring plate portions 132 extending radially outward from the outer peripheral edge portion of the main body portion 131. A plurality of spring plate portions 132 are formed at equal intervals in the circumferential direction of the main body portion 131 on the first spring member 122. As shown in FIG. 4, the spring plate portions 132 are inclined so as to be axially separated from the main body portion 131 as they are located more outside in the radial direction of the main body portion 131. As shown in FIG. 2, the first spring member 122 has the mounting shaft portion 33 of the piston rod 31 fitted to the inner side in the radial direction of the main body portion 131, and a plurality of spring plate portions 132 extend from the main body portion 131 in the axial direction of the mounting shaft portion 33 toward the first intermediate valve disk 125 and abut against the first intermediate valve disk 125. Thereby, the first spring member 122 presses the first intermediate valve disk 125 against the first intermediate valve seat portion 86 to seat it.

[0056] The second sleeve 123 is cylindrical and has the mounting shaft portion 33 fitted to the inner side in the radial direction. The second sleeve 123 clamps the main body portion 131 of the first spring member 122 together with the first sleeve 121.

[0057] The second intermediate valve disk 126 is in the shape of a perforated disk and is disposed inside the guide hole 74 of the piston 21. The outer side of the second intermediate valve disk 126 in the radial direction is guided by the inner peripheral surface of the guide hole 74 of the piston 21 and moves in the axial direction of the piston 21. The second intermediate valve disk 126 abuts against the second intermediate valve seat portion 88 to close the passage groove 89. When the second intermediate valve disk 126 separates from the second intermediate valve seat portion 88, the passage groove 89 is opened.

[0058] The second spring member 124 has the same shape as the first spring member 122 and has a larger outer diameter than the first spring member 122. The second spring member 124 has a perforated disk-shaped main body portion 135 and a spring plate portion 136 that extends radially outward from the outer peripheral edge portion of the main body portion 135. The spring plate portion 136 is inclined so as to be axially separated from the main body portion 135 as it is located more outside the main body portion 135 in the radial direction. A plurality of spring plate portions 136 are formed at equal intervals in the circumferential direction of the main body portion 135 of the second spring member 124. The second spring member 124 has a mounting shaft portion 33 fitted inside the main body portion 135 in the radial direction, and a plurality of spring plate portions 136 extend from the main body portion 135 in the direction of the second intermediate valve disk 126 in the axial direction of the mounting shaft portion 33 and abut against the second intermediate valve disk 126. Thereby, the second spring member 124 presses the second intermediate valve disk 126 against the second intermediate valve seat portion 88 to seat it. The main body portion 135 of the second spring member 124 is sandwiched between the second sleeve 123 and the disk 101.

[0059] The piston rod 31 has a threaded shaft portion 34 disposed at a portion protruding from the annular member 116. A nut member 138 is screwed onto the external thread 35 on the outer periphery of the threaded shaft portion 34. As a result, the annular member 105, the disk 104, the disk 103, the disk 102, the disk 101, the main body portion 135 of the second spring member 124, the second sleeve 123, the main body portion 131 of the first spring member 122, the first sleeve 121, the piston 21, the disk 111, the disk 112, the disk 113, the disk 114, the disk 115, and the annular member 116 are axially clamped on at least their inner peripheral sides by the main shaft portion 32 and the nut member 138, respectively.

[0060] The portion surrounded by the disk 102, the disk 101, the main body portion 135 of the second spring member 124, the second sleeve 123, the main body portion 131 of the first spring member 122, the first sleeve 121, the piston 21, the first intermediate valve disk 125, and the second intermediate valve disk 126 forms the piston inner chamber 140.

[0061] The disk 101 and the plurality of disks 102 constitute the first valve member 141. The first valve member 141 abuts against the first valve seat portion 81 of the piston 21 to close the piston inner chamber 140. When the first valve member 141 separates from the first valve seat portion 81 of the piston 21, the piston inner chamber 140 is opened to the upper chamber 22.

[0062] The passage grooves 87 in the piston 21 and the plurality of passage holes 91 constitute a passage portion 143. When the first intermediate valve disk 125 opens, the passage portion 143 communicates with the inner chamber 140 of the piston. The passage portion 143, the passage between the opened first intermediate valve disk 125 and the first intermediate valve seat portion 86, the inner chamber 140 of the piston, and the passage between the first valve member 141 in the open state and the first valve seat portion 81 constitute a first passage 145. The first passage 145 penetrates the piston body 61 in the axial direction. The passage portion 143 of the first passage 145 is always in communication with the lower chamber 23. The first passage 145 is provided in the piston 21 and communicates the lower chamber 23 and the upper chamber 22. The first passage 145 appears only when the first valve member 141 separates from the first valve seat portion 81 and opens.

[0063] The first valve member 141 and the first valve seat portion 81 form a first damping force generating mechanism 146 that opens the first passage 145 and allows the hydraulic fluid L to flow through the first passage 145. When opening the valve, the first damping force generating mechanism 146 allows the hydraulic fluid L to flow from the lower chamber 23 to the upper chamber 22 through the first passage 145. Therefore, the first damping force generating mechanism 146 directs the hydraulic fluid L flowing out of the lower chamber 23 toward the upper chamber 22 during the movement of the piston 21 toward the lower chamber 23 side, that is, during the compression stroke. At this time, the first damping force generating mechanism 146 suppresses the flow of the hydraulic fluid L from the lower chamber 23 to the upper chamber 22 through the first passage 145 to generate a damping force. That is, the first damping force generating mechanism 146 is provided in the first passage 145 and serves as a damping force generating mechanism on the compression side that opens when the hydraulic fluid L moves from the lower chamber 23 to the upper chamber 22.

[0064] The first intermediate valve disk 125, the first intermediate valve seat portion 86, and the first spring member 122 constitute the first valve mechanism 148. When the first intermediate valve disk 125 abuts against the first intermediate valve seat portion 86 of the piston 21 by the biasing force of the first spring member 122, the passage portion 143 is closed. When the first intermediate valve disk 125 separates from the first intermediate valve seat portion 86 of the piston 21 against the biasing force of the first spring member 122, the passage portion 143 is opened to the piston inner chamber 140. The first valve mechanism 148 is a check valve that allows the flow of the hydraulic fluid L from the passage portion 143 to the piston inner chamber 140 and restricts the flow of the hydraulic fluid L from the piston inner chamber 140 to the passage portion 143. The first valve mechanism 148 is provided in the first passage 145, is disposed on the lower chamber 23 side of the first damping force generating mechanism 146, and is opened by the movement of the hydraulic fluid L from the lower chamber 23 to the upper chamber 22.

[0065] The disk 111, the plurality of disks 112, and the disk 113 constitute the second valve member 151. The second valve member 151 abuts against the second valve seat portion 82 of the piston 21 to close the passage in the passage recess 84. When the second valve member 151 separates from the second valve seat portion 82 of the piston 21, the passage in the passage recess 84 is opened to the lower chamber 23. The second valve member 151 has a larger number of stacked disks of the disk 111, the disk 112, and the disk 113 than the stacked number of the disks 101 and 102 of the first valve member 141, and thus has higher rigidity than the first valve member 141.

[0066] The passage in the plurality of passage holes 94 in the piston 21, the passage in the passage recess 84, and the passage between the second valve member 151 in the open valve state and the second valve seat portion 82 constitute the second passage 152. The second passage 152 axially penetrates the piston body 61. The second passage 152 is always in communication with the upper chamber 22. The second passage 152 is provided in the piston 21 and communicates the upper chamber 22 and the lower chamber 23. The second passage 152 appears only when the second valve member 151 separates from the second valve seat portion 82 and opens the valve.

[0067] The second valve member 151 and the second valve seat portion 82 form a second damping force generating mechanism 153 that opens the second passage 152 and allows the hydraulic fluid L to flow through the second passage 152. When the second damping force generating mechanism 153 is opened, the hydraulic fluid L flows from the upper chamber 22 to the lower chamber 23 through the second passage 152. Therefore, in the second damping force generating mechanism 153, when the piston 21 moves toward the upper chamber 22 side, that is, in the extension stroke, the hydraulic fluid L flowing out of the upper chamber 22 flows toward the lower chamber 23. At this time, the second damping force generating mechanism 153 suppresses the flow of the hydraulic fluid L from the upper chamber 22 to the lower chamber 23 through the second passage 152 to generate a damping force. That is, the second damping force generating mechanism 153 is provided in the second passage 152 and serves as a damping force generating mechanism on the extension side that opens when the hydraulic fluid L moves from the upper chamber 22 to the lower chamber 23.

[0068] The passages in the plurality of passage holes 97 of the piston 21 and the passages in the passage groove 89 form a third passage 161. The third passage 161 is always in communication with the upper chamber 22 through the passage in the passage hole 94. The third passage 161 is connected between the upper chamber 22 and the second damping force generating mechanism 153 in the second passage 152 and between the first damping force generating mechanism 146 and the first valve mechanism 148 in the first passage 145, and communicates the second passage 152 and the first passage 145.

[0069] The second intermediate valve disk 126, the second intermediate valve seat portion 88, and the second spring member 124 constitute the second valve mechanism 162. When the second intermediate valve disk 126 abuts against the second intermediate valve seat portion 88 of the piston 21 by the biasing force of the second spring member 124, the second valve mechanism 162 closes the third passage 161. When the second intermediate valve disk 126 separates from the second intermediate valve seat portion 88 of the piston 21 against the biasing force of the second spring member 124, the second valve mechanism 162 opens the third passage 161 to the piston inner chamber 140. The second valve mechanism 162 is a check valve that allows the flow of the hydraulic fluid L from the third passage 161 to the piston inner chamber 140 and restricts the flow of the hydraulic fluid L from the piston inner chamber 140 to the third passage 161. The second valve mechanism 162 is provided in the third passage 161 and opens when the hydraulic fluid L moves from the second passage 152 to the first passage 145 through the third passage 161. The second valve mechanism 162 introduces a part of the hydraulic fluid L into the piston inner chamber 140 when flowing the hydraulic fluid L from the upper chamber 22 to the lower chamber 23.

[0070] Here, when the first damping force generating mechanism 146 is in the closed state, the passage in the notch 107 of the disk 101 of the first valve member 141 constitutes the first orifice portion 171. The piston inner chamber 140 and the first orifice portion 171 between the first valve member 141 in the closed state and the first valve seat portion 81 constitute the fourth passage 172.

[0071] Thus, the fourth passage 172 includes the first orifice portion 171 between the first valve member 141 in the closed state and the first valve seat portion 81. Therefore, the fourth passage 172 is provided in parallel to the first passage 145 separately from the first passage 145 that includes the passage between the first valve member 141 in the open state and the first valve seat portion 81. The first orifice portion 171, which is at least a part of the fourth passage 172, suppresses the flow rate of the hydraulic fluid L more than the first passage 145 that includes the passage between the first valve member 141 in the open state of the first damping force generating mechanism 146 and the first valve seat portion 81.

[0072] Therefore, the shock absorber 1 is provided in parallel with the first passage 145 including the passage between the first valve member 141 in the open valve state and the first valve seat portion 81, and includes the first orifice portion 171 between the first valve member 141 in the closed valve state and the first valve seat portion 81, and has a fourth passage 172 that communicates the upper chamber 22 with the piston inner chamber 140 between the first damping force generating mechanism 146 and the first valve mechanism 148 in the first passage 145. At least a part of the fourth passage 172 is provided with a first orifice portion 171 that suppresses the flow rate of the hydraulic fluid L more than the first passage 145 including the passage between the first valve member 141 in the open valve state of the first damping force generating mechanism 146 and the first valve seat portion 81.

[0073] Note that the first orifice portion 171 can also be formed in the piston 21, for example, by providing a notch in the position where the first valve seat portion 81 abuts against the first valve member 141, or by providing a hole portion that communicates the piston inner chamber 140 and the upper chamber 22 at a position different from the first valve seat portion 81, in addition to being formed by the notch portion 107 of the disk 101 of the first valve member 141.

[0074] When the second damping force generating mechanism 153 is in the closed valve state, the passage in the notch portion 117 of the disk 111 of the second valve member 151 constitutes the second orifice portion 175. When the second damping force generating mechanism 153 is in the closed valve state, the passage in the plurality of passage holes 94 of the piston 21 and the passage in the passage recess 84 and the second orifice portion 175 between the second valve member 151 in the closed valve state and the second valve seat portion 82 constitute the fifth passage 176.

[0075] The fifth passage 176 includes a second orifice portion 175 between the second valve member 151 in the closed valve state and the second valve seat portion 82. Therefore, the fifth passage 176 is provided in parallel to the second passage 152, which includes a passage between the second valve member 151 in the open valve state of the second damping force generating mechanism 153 and the second valve seat portion 82, separately from the second passage 152. At least a part of the second orifice portion 175 of the fifth passage 176 suppresses the flow rate of the hydraulic fluid L more than the second passage 152, which includes a passage between the second valve member 151 in the open valve state of the second damping force generating mechanism 153 and the second valve seat portion 82.

[0076] Therefore, the shock absorber 1 is provided in parallel to the second passage 152, which includes a passage between the second valve member 151 in the open valve state of the second damping force generating mechanism 153 and the second valve seat portion 82, and includes a fifth passage 176 that communicates the lower chamber 23 and the upper chamber 22. At least a part of the fifth passage 176 includes a second orifice portion 175 that suppresses the flow rate of the hydraulic fluid L more than the second passage 152, which includes a passage between the second valve member 151 in the open valve state of the second damping force generating mechanism 153 and the second valve seat portion 82.

[0077] In addition to being formed by the notch portion 117 of the disk 111 of the second valve member 151, the second orifice portion 175 can also be formed in the piston 21, for example, by providing a notch portion at a position where the second valve seat portion 82 abuts against the first valve member 141, or by providing a hole portion that communicates the passage in the passage hole 94 and the lower chamber 23 at a position different from the second valve seat portion 82.

[0078] In the shock absorber 1, when the configuration provided on the piston rod 31 to allow the hydraulic fluid L to flow between the upper chamber 22 and the lower chamber 23 is shown as a hydraulic circuit, it becomes as shown in FIG. 5.

[0079] As shown in FIG. 5, the shock absorber 1 includes a first passage 145 that communicates the lower chamber 23 and the upper chamber 22, and a second passage 152 that communicates the upper chamber 22 and the lower chamber 23.

[0080] Further, the shock absorber 1 includes a first damping force generating mechanism 146 provided in the first passage 145 that opens when the hydraulic fluid L moves from the lower chamber 23 to the upper chamber 22, and a second damping force generating mechanism 153 provided in the second passage 152 that opens when the hydraulic fluid L moves from the upper chamber 22 to the lower chamber 23.

[0081] Further, the shock absorber 1 includes a first valve mechanism 148 provided in the first passage 145, disposed on the lower chamber 23 side of the first damping force generating mechanism 146, and opening when the hydraulic fluid L moves from the lower chamber 23 to the upper chamber 22.

[0082] Further, the shock absorber 1 is connected between the upper chamber 22 and the second damping force generating mechanism 153 in the second passage 152 and between the first damping force generating mechanism 146 and the first valve mechanism 148 in the first passage 145, and includes a third passage 161 that communicates the second passage 152 and the first passage 145, and a second valve mechanism 162 provided in the third passage 161 that opens when the hydraulic fluid L moves from the second passage 152 to the first passage 145.

[0083] Further, the shock absorber 1 includes a fourth passage 172 provided in parallel with the first passage 145, communicating the upper chamber 22 and the space between the first damping force generating mechanism 146 and the first valve mechanism 148 in the first passage 145, and the fourth passage 172 includes a first orifice portion 171.

[0084] Further, the shock absorber 1 includes a fifth passage 176 provided in parallel with the second passage 152, communicating the lower chamber 23 and the upper chamber 22, and the fifth passage 176 includes a second orifice portion 175.

[0085] As shown in FIG. 1, the above-described base valve 15 is provided between the bottom portion 9 of the outer cylinder 3 and the inner cylinder 2. This base valve 15 includes the above-described valve body 12 that partitions the lower chamber 23 and the reservoir chamber 5, a disk 202 provided on the lower side of this valve body 12, that is, on the reservoir chamber 5 side, a disk 203 provided on the upper side of the valve body 12, that is, on the lower chamber 23 side, and a mounting pin 204 that attaches the disk 202 and the disk 203 to the valve body 12.

[0086] The valve body 12 is annular, and the mounting pin 204 is inserted through the center in the radial direction. The valve body 12 is formed with a plurality of passage holes 205 through which the hydraulic fluid L can flow between the lower chamber 23 and the reservoir chamber 5, and a plurality of passage holes 206 through which the hydraulic fluid L can flow between the lower chamber 23 and the reservoir chamber 5 on the outer side in the radial direction of the valve body 12 with respect to these passage holes 205. The disk 202 on the reservoir chamber 5 side allows the flow of the hydraulic fluid L from the lower chamber 23 to the reservoir chamber 5 through the passage holes (not shown in the figure) of the disk 203 and the passage holes 205 of the valve body 12, while suppressing the flow of the hydraulic fluid L from the reservoir chamber 5 to the lower chamber 23 through the passage holes 205 and the passage holes (not shown in the figure) of the disk 203. The disk 203 allows the flow of the hydraulic fluid L from the reservoir chamber 5 to the lower chamber 23 through the passage holes 206, while suppressing the flow of the hydraulic fluid L from the lower chamber 23 to the reservoir chamber 5 through the passage holes 206.

[0087] The disk 202 and the valve body 12 constitute a compression-side damping valve mechanism 207 that opens the valve during the compression stroke of the shock absorber 1 to allow the hydraulic fluid L to flow from the lower chamber 23 to the reservoir chamber 5 and generate a damping force. The disk 203 and the valve body 12 constitute a suction valve mechanism 208 that opens the valve during the extension stroke of the shock absorber 1 to allow the hydraulic fluid L to flow from the reservoir chamber 5 into the lower chamber 23. The suction valve mechanism 208 mainly functions to allow the hydraulic fluid L to flow from the reservoir chamber 5 to the lower chamber 23 without substantially generating a damping force to compensate for the shortage of the fluid caused by the extension of the piston rod 31 from the cylinder 4.

[0088] Next, the operation of the configuration provided on the piston rod 31 of the shock absorber 1 will be described.

[0089] In the extending stroke, as the piston 21 moves toward the upper chamber 22 side, the pressure in the upper chamber 22 increases and the pressure in the lower chamber 23 decreases. When the piston speed is less than the first predetermined value during the extending stroke, the second damping force generating mechanism 153 does not open its valve. Therefore, the hydraulic fluid L from the upper chamber 22 flows into the lower chamber 23 through the fifth passage 176 including the passages in the plurality of passage holes 94 of the piston 21 and the passages in the passage recess 84, and the second orifice portion 175 between the second valve member 151 in the valve-closed state and the second valve seat portion 82.

[0090] In the region where the piston speed is equal to or greater than the first predetermined value, the flow path is constricted at the second orifice portion 175 of the fifth passage 176, so that the pressure applied to the second valve member 151 from the passages in the plurality of passage holes 94 of the piston 21 and the passages in the passage recess 84 increases, and the second valve member 151 separates from the second valve seat portion 82 to open the second damping force generating mechanism 153. As a result, the hydraulic fluid L from the upper chamber 22 flows into the lower chamber 23 through the second passage 152 including the passage between the second valve member 151 and the second valve seat portion 82 of the opened second damping force generating mechanism 153.

[0091] Here, in the extending stroke with a slow piston speed, as the piston 21 moves toward the upper chamber 22 side, the pressure in the upper chamber 22 increases and the pressure in the lower chamber 23 decreases. Then, the hydraulic fluid L in the upper chamber 22 is introduced into the piston inner chamber 140 through the first orifice portion 171 of the fourth passage 172, and the pressure in the piston inner chamber 140 also increases, suppressing the expansion of the pressure difference between the upper chamber 22 and the piston inner chamber 140. At this time, the first valve mechanism 148 in the valve-closed state suppresses the pressure from escaping to the lower chamber 23 through the first passage 145.

[0092] In the fast extending stroke of the piston speed, the flow path is narrowed at the second orifice portion 175, so that the pressure in the passages in the plurality of passage holes 94 of the piston 21 and from the third passage 161 to the second valve mechanism 162 increases. The second intermediate valve disk 126 of the second valve mechanism 162 separates from the second intermediate valve seat portion 88 against the biasing force of the second spring member 124 and opens the valve. As a result, the upper chamber 22 and the piston inner chamber 140 communicate with each other through the passage in the passage hole 94, the third passage 161, and the passage between the opened second intermediate valve disk 126 and the second intermediate valve seat portion 88 of the second valve mechanism 162. As a result, when the pressure in the upper chamber 22 rises, the pressure in the piston inner chamber 140 also rises accordingly, suppressing the expansion of the pressure difference between the upper chamber 22 and the piston inner chamber 140. At that time, the first valve mechanism 148 in the closed valve state suppresses the pressure from escaping to the lower chamber 23 through the passage portion 143 of the first passage 145.

[0093] In the contracting stroke, when the piston 21 moves toward the lower chamber 23 side, the pressure in the lower chamber 23 increases and the pressure in the upper chamber 22 decreases. In the contracting stroke where the piston speed is less than the second predetermined value, the oil fluid L from the lower chamber 23 flows to the upper chamber 22 through the second orifice portion 175 between the second valve member 151 and the second valve seat portion 82, the passage in the passage recess 84 of the piston 21, and the passages in the plurality of passage holes 94. Further, the oil fluid L from the lower chamber 23 passes through the passages in the plurality of passage holes 91 in the piston 21 and the passage portion 143 in the passage groove 87, and opens the first intermediate valve disk 125 of the first valve mechanism 148 to separate from the first intermediate valve seat portion 86 against the biasing force of the first spring member 122, and flows to the upper chamber 22 through the fourth passage 172 including the first orifice portion 171 between the first valve member 141 and the first valve seat portion 81. At that time, the second valve mechanism 162 in the closed valve state suppresses the pressure from escaping to the upper chamber 22 through the third passage 161 and the passages in the passage holes 94.

[0094] In the compression stroke, in a region where the piston speed is equal to or higher than a second predetermined value, the first valve member 141 separates from the first valve seat portion 81 and the first damping force generating mechanism 146 opens the valve. As a result, the hydraulic fluid L from the lower chamber 23 flows into the upper chamber 22 through a first passage 145 including a passage portion 143, a passage between the first intermediate valve disk 125 of the opened first valve mechanism 148 and the first intermediate valve seat portion 86, a piston inner chamber 140, and a passage between the first valve member 141 of the opened first damping force generating mechanism 146 and the first valve seat portion 81. Also at this time, the second valve mechanism 162 in the closed valve state suppresses the pressure from escaping into the upper chamber 22 through the third passage 161 and the passage in the passage hole 94.

[0095] Patent Document 1 described above discloses a shock absorber provided with a damping force generating mechanism that generates a damping force during an extension stroke in which a rod extends from a cylinder, and a damping force generating mechanism that generates a damping force during a compression stroke in which the rod enters the cylinder. By the way, in a shock absorber, it is required to improve durability. For example, in a damping force generating mechanism that generates a damping force during one of the extension stroke and the compression stroke, back pressure is applied during the other stroke, and this back pressure may affect the durability of the damping force generating mechanism. In particular, in vehicles that need to generate a high damping force, such as large vehicles with a heavy vehicle weight or electric vehicles, the possibility is high.

[0096] The shock absorber 1 is provided on the piston 21 and has a first passage 145 and a second passage 152 that communicate the lower chamber 23 and the upper chamber 22, a first damping force generating mechanism 146 provided in the first passage 145 that opens when the oil fluid L as the working fluid moves from the lower chamber 23 to the upper chamber 22, and a second damping force generating mechanism 153 provided in the second passage 152 that opens when the oil fluid L moves from the upper chamber 22 to the lower chamber 23. And, in the shock absorber 1, a first valve mechanism 148 is provided in the first passage 145 on the lower chamber 23 side of the first damping force generating mechanism 146 and opens when the oil fluid L moves from the lower chamber 23 to the upper chamber 22. Further, the shock absorber 1 is connected between the upper chamber 22 and the second damping force generating mechanism 153 in the second passage 152 and between the first damping force generating mechanism 146 and the first valve mechanism 148 in the first passage 145, and a third passage 161 that communicates the second passage 152 and the first passage 145 is provided. In addition, the shock absorber 1 is provided with a second valve mechanism 162 in the third passage 161 that opens when the oil fluid L moves from the second passage 152 to the first passage 145. As a result, in the extension stroke where the pressure in the upper chamber 22 increases and the pressure in the lower chamber 23 decreases, the second valve mechanism 162 provided in the third passage 161 opens and the pressure in the upper chamber 22 can be introduced into the first passage 145 via the second passage 152 and the third passage 161. At that time, the first valve mechanism 148 suppresses the pressure in the lower chamber 23 from escaping. Therefore, it becomes possible to apply pressure to the first damping force generating mechanism 146 following the pressure in the upper chamber 22 from the side opposite to the upper chamber 22. Therefore, the differential pressure between the upper chamber 22 side and the side between the first damping force generating mechanism 146 and the first valve mechanism 148 on the side opposite to the upper chamber 22 in the first damping force generating mechanism 146 can be suppressed. Therefore, the durability of the shock absorber 1 can be improved. As a result, it becomes possible to generate a high damping force. Also, the tunable range can be expanded.

[0097] Here, generally in a shock absorber, the damping force on the compression side is set to be lower than the damping force on the extension side. Also in the shock absorber 1 of the embodiment, the rigidity of the first valve member 141 that constitutes the first damping force generation mechanism 146 is lower than the rigidity of the second valve member 151 that constitutes the second damping force generation mechanism 153, so that the damping force on the compression side is lower than the damping force on the extension side. For this reason, it is desirable to improve the durability of the first valve member 141 that constitutes the first damping force generation mechanism 146, which has particularly low rigidity. That is, when a high pressure is applied from the upper chamber 22 side, the first valve member 141 is likely to deform so as to enter the concave portion on the radially inner side of the first valve seat portion 81, and thus the durability is likely to be affected. In the shock absorber 1 of the embodiment, since the pressure can be applied to the first damping force generation mechanism 146 that generates the damping force on the compression side from the side opposite to the upper chamber 22 following the pressure in the upper chamber 22, the durability can be effectively improved.

[0098] Further, in parallel with the first passage 145 that appears when the first damping force generation mechanism 146 of the shock absorber 1 opens, a fourth passage 172 is provided that communicates the upper chamber 22 with the space between the first damping force generation mechanism 146 and the first valve mechanism 148 in the first passage 145 when the first damping force generation mechanism 146 closes. At least a part of this fourth passage 172 is provided with a first orifice portion 171 that suppresses the flow rate of the hydraulic fluid L more than the first passage 145. As a result, in the extension stroke where the pressure in the upper chamber 22 increases and the pressure in the lower chamber 23 decreases, the shock absorber 1 can introduce the pressure in the upper chamber 22 between the first damping force generation mechanism 146 and the first valve mechanism 148 even through the fourth passage 172 having the first orifice portion 171. At that time, the first valve mechanism 148 suppresses the pressure from escaping to the lower chamber 23. Therefore, it becomes possible to apply a pressure to the first damping force generation mechanism 146 from the side opposite to the upper chamber 22 following the pressure in the upper chamber 22. Therefore, the differential pressure between the upper chamber 22 side and the space between the first damping force generation mechanism 146 and the first valve mechanism 148, which is the side opposite to the upper chamber 22 in the first damping force generation mechanism 146, can be suppressed. Therefore, the durability of the shock absorber 1 can be improved.

[0099] Further, the shock absorber 1 is provided in parallel with the second passage 152 that appears when the second damping force generation mechanism 153 opens, and includes a fifth passage 176 that communicates the lower chamber 23 and the upper chamber 22 when the second damping force generation mechanism 153 closes. At least a part of this fifth passage 176 is provided with a second orifice portion 175 that suppresses the flow rate of the hydraulic fluid L more than the second passage 152. Therefore, in the extension stroke in which the hydraulic fluid L flows from the upper chamber 22 to the lower chamber 23, it becomes possible to generate a damping force with orifice characteristics at the second orifice portion 175.

[0100] The shock absorber 1 is provided on the piston 21 and includes a first passage 145 and a second passage 152 that communicate the lower chamber 23 and the upper chamber 22, a first damping force generation mechanism 146 provided in the first passage 145 that opens when the hydraulic fluid L as the working fluid moves from the lower chamber 23 to the upper chamber 22, and a second damping force generation mechanism 153 provided in the second passage 152 that opens when the hydraulic fluid L moves from the upper chamber 22 to the lower chamber 23. The shock absorber 1 is provided with a first valve mechanism 148 that is disposed on the lower chamber 23 side of the first damping force generation mechanism 146 in the first passage 145 and opens when the hydraulic fluid L moves from the lower chamber 23 to the upper chamber 22. Further, in parallel with the first passage 145 that appears when the first damping force generation mechanism 146 opens, the shock absorber 1 is provided with a fourth passage 172 that communicates the upper chamber 22 and between the first damping force generation mechanism 146 and the first valve mechanism 148 in the first passage 145 when the first damping force generation mechanism 146 closes. At least a part of this fourth passage 172 is provided with a first orifice portion 171 that suppresses the flow rate of the hydraulic fluid L more than the first passage 145. As a result, in the extension stroke in which the pressure in the upper chamber 22 increases and the pressure in the lower chamber 23 decreases, the shock absorber 1 can introduce the pressure in the upper chamber 22 between the first damping force generation mechanism 146 and the first valve mechanism 148 through the fourth passage 172 having the first orifice portion 171. At that time, the first valve mechanism 148 suppresses the pressure from escaping to the lower chamber 23. Therefore, it becomes possible to apply pressure to the first damping force generation mechanism 146 following the pressure in the upper chamber 22 from the side opposite to the upper chamber 22. Therefore, the differential pressure between the upper chamber 22 side and between the first damping force generation mechanism 146 and the first valve mechanism 148 in the first damping force generation mechanism 146 can be suppressed. Therefore, it becomes possible to improve the durability of the shock absorber 1.

[0101] In the embodiment, the case where leaf springs are used as the first spring member 122 and the second spring member 124 has been described as an example. However, it is also possible to use a first spring member 122A which is a coil spring as shown in FIG. 6 in place of the first spring member 122, or to use a similar coil spring in place of the second spring member 124.

Explanation of Reference Numerals

[0102] 1... shock absorber, 4... cylinder, 21... piston, 22... upper chamber (second chamber), 23... lower chamber (first chamber), 31... piston rod, 145... first passage, 146... first damping force generating mechanism, 148... first valve mechanism, 152... second passage, 153... second damping force generating mechanism, 161... third passage, 162... second valve mechanism, 171... first orifice portion, 172... fourth passage, 175... second orifice portion, 176... fifth passage, L... hydraulic fluid (working fluid).

Claims

1. A cylinder, A working fluid provided in the cylinder, A piston provided in the cylinder and partitioning the inside of the cylinder into a first chamber and a second chamber, A piston rod having a first end connected to the piston and a second end extending from the cylinder, A first passage and a second passage provided in the piston and communicating the first chamber and the second chamber, A first damping force generating mechanism provided in the first passage and opening a valve when the working fluid moves from the first chamber to the second chamber, A second damping force generating mechanism provided in the second passage and opening a valve when the working fluid moves from the second chamber to the first chamber, A first valve mechanism provided in the first passage, disposed on the first chamber side of the first damping force generating mechanism, and opening a valve when the working fluid moves from the first chamber to the second chamber, A third passage connected between the second chamber and the second damping force generating mechanism in the second passage and between the first damping force generating mechanism and the first valve mechanism in the first passage and communicating the second passage and the first passage, A second valve mechanism provided in the third passage and opening a valve when the working fluid moves from the second passage to the first passage, A shock absorber comprising the above.

2. The shock absorber according to claim 1, comprising a fourth passage provided in parallel with the first passage and communicating the second chamber and between the first damping force generating mechanism and the first valve mechanism in the first passage, The shock absorber, wherein at least a part of the fourth passage comprises a first orifice portion that suppresses the flow rate of the working fluid more than the first passage.

3. The shock absorber according to any one of claims 1 or 2, comprising a fifth passage provided in parallel with the second passage and communicating the first chamber and the second chamber, The fifth passage is a shock absorber including at least a part thereof having a second orifice portion that suppresses the flow rate of the working fluid more than the second passage.

4. A cylinder, a working fluid provided in the cylinder, a piston provided in the cylinder and partitioning the inside of the cylinder into a first chamber and a second chamber, a piston rod having a first end connected to the piston and a second end extending from the cylinder, a first passage and a second passage provided in the piston and communicating the first chamber and the second chamber, a first damping force generating mechanism provided in the first passage and opening a valve when the working fluid moves from the first chamber to the second chamber, a second damping force generating mechanism provided in the second passage and opening a valve when the working fluid moves from the second chamber to the first chamber, a first valve mechanism provided in the first passage, disposed on the first chamber side rather than the first damping force generating mechanism, and opening a valve when the working fluid moves from the first chamber to the second chamber, a fourth passage provided in parallel with the first passage and communicating the second chamber and a position between the first damping force generating mechanism and the first valve mechanism in the first passage, The fourth passage is a shock absorber including at least a part thereof having a first orifice portion that suppresses the flow rate of the working fluid more than the first passage.

5. The shock absorber according to claim 4, including a fifth passage provided in parallel with the second passage and communicating the first chamber and the second chamber, wherein at least a part of the fifth passage has a second orifice portion that suppresses the flow rate of the working fluid more than the second passage.

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