Shock absorber

Abstract

A damper is provided with: a tube; a piston rod, one end of which in the axial direction is disposed inside the tube and the other end of which in the axial direction is disposed outside the tube; a piston assembly which is connected to the axial middle position of the piston rod, divides the inner chamber of the tube into a first chamber on the other end side of the piston rod and a second chamber on the one end side, and generates a damping force when the piston rod moves; and a damping force increasing mechanism that increases the damping force when the piston assembly moves toward the second chamber side. The damping force increasing mechanism is provided with: a first cylinder connected to the piston rod at a position closer to one end than the piston assembly; and a partition piston that forms a partition chamber in the first cylinder by entering the first cylinder when the piston assembly moves toward the second chamber side.

Description

Technical Field

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

[0002] This application claims priority based on U.S. patent application No. 18 / 121,649 filed in the United States on March 15, 2023, the contents of which are incorporated herein by reference. Background Art

[0003] There is a shock absorber that increases the damping force when the piston rod reaches a predetermined range on the limit side during a contraction stroke in which the piston rod is pushed into the tube (for example, see Patent Document 1 listed below).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: (U.S.) Patent No. 10107352 Summary of the Invention

[0007] Technical problem to be solved by the invention

[0008] However, in the shock absorber, it is desired to suppress an increase in cost.

[0009] Therefore, an object of the present invention is to provide a shock absorber capable of suppressing cost increase.

[0010] Technical solutions to technical problems

[0011] In order to achieve the above-mentioned purpose, one scheme of the shock absorber of the present invention comprises: a tube, the inner side of which becomes an inner chamber; a piston rod, one axial end of which is arranged in the tube, and the other axial end is arranged outside the tube; a piston assembly, which is connected to the middle position of the axial direction of the piston rod, divides the inner chamber into a first chamber on the other end side of the piston rod and a second chamber on the one end side, and generates a damping force when the piston rod moves; a damping force increasing mechanism, which increases the damping force when the piston assembly moves toward the second chamber side, and the damping force increasing mechanism comprises: a first cylinder, which is connected to a position of the piston rod closer to the one end side than the piston assembly; a dividing piston, which enters the inner side of the first cylinder when the piston assembly moves toward the second chamber side to form a divided chamber in the first cylinder.

[0012] Effects of the Invention

[0013] According to the shock absorber of the above-described aspect of the present invention, it is possible to suppress an increase in cost. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0015] Figure 2 It is a cross-sectional view showing the main parts of the shock absorber according to the first embodiment of the present invention.

[0016] Figure 3 It is a perspective view showing a base adapter of the shock absorber according to the first embodiment of the present invention.

[0017] Figure 4 It is a cross-sectional view showing the main parts of the shock absorber according to the first embodiment of the present invention.

[0018] Figure 5 It is a cross-sectional view showing a main part of a shock absorber according to a second embodiment of the present invention.

[0019] Figure 6 This is an exploded perspective view showing a divided piston of a shock absorber according to a second embodiment of the present invention.

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

[0021] Figure 8 It is a perspective sectional view showing a movable ring support body of a damper according to a third embodiment of the present invention.

[0022] Figure 9 It is a cross-sectional view showing a main part of a shock absorber according to a fourth embodiment of the present invention.

[0023] Figure 10 This is an exploded perspective view showing a portion of a divided piston of a shock absorber according to a fourth embodiment of the present invention.

[0024] Figure 11 It is a cross-sectional view showing a main part of a shock absorber according to a fifth embodiment of the present invention.

[0025] Figure 12 It is an exploded perspective sectional view showing a valve body assembly of a shock absorber according to a fifth embodiment of the present invention.

[0026] Figure 13 It is a cross-sectional view showing a main part of a shock absorber according to a sixth embodiment of the present invention. DETAILED DESCRIPTION

[0027] [First embodiment]

[0028] based on Figures 1 to 4 A shock absorber according to a first embodiment of the present invention will be described. In the following, for convenience of description, the upper side in the drawings will be referred to as "upper" and the lower side in the drawings will be referred to as "lower."

[0029] like Figure 1As shown, the shock absorber 1 of the first embodiment is a double-tube hydraulic shock absorber. The shock absorber 1 is used in a vehicle, specifically, in a suspension system for an automobile. The shock absorber 1 includes a cylinder 2. The cylinder 2 has a tube 3 and a housing 5. The tube 3 is cylindrical. The housing 5 is cylindrical with a bottom. The inner diameter of the housing 5 is larger than the outer diameter of the tube 3. The tube 3 is positioned radially inward of the housing 5. The central axis of the tube 3 coincides with the central axis of the housing 5. The inner side of the tube 3 forms an inner chamber 6. The space between the tube 3 and the housing 5 forms a storage chamber 7.

[0030] The housing 5 includes a main body 11 and a bottom 12. The main body 11 is cylindrical. The bottom 12 is circular and fits inside the lower portion of the main body 11. The entire circumference of the bottom 12 is joined to the main body 11 by welding or the like. The bottom 12 seals the lower portion of the main body 11.

[0031] The shock absorber 1 includes a piston assembly 17. The piston assembly 17 is arranged in the tube 3 of the cylinder 2. The piston assembly 17 includes a piston 18. The piston 18 of the piston assembly 17 is slidably embedded in the tube 3. The piston 18 divides the inner chamber 6 in the tube 3 into two chambers: a first chamber 19 on one side and a second chamber 20 on the other side. In the axial direction of the tube 3, the first chamber 19 is located on the side opposite to the bottom member 12 than the piston 18. In the axial direction of the tube 3, the second chamber 20 is located on the side closer to the bottom member 12 than the piston 18. In the cylinder 2, oil L as a working fluid is sealed in the inner chamber 6 in the tube 3. In the cylinder 2, oil L and gas G as a working fluid are sealed in the storage chamber 7 between the tube 3 and the housing 5.

[0032] The shock absorber 1 includes a piston rod 21. A first end 22, one axial end of the piston rod 21, is disposed within the tube 3 of the cylinder 2. A second end 23, the other axial end of the piston rod 21, is disposed outside the cylinder 2. The piston assembly 17 is connected to the piston rod 21 at a position intermediate between the first and second axial ends 22, 23, on the side closer to the first end 22. The piston rod 21 is connected to the piston assembly 17 and extends outward from the tube 3 and the housing 5, i.e., the cylinder 2, through the first chamber 19. The piston assembly 17 divides the inner chamber 6 into a first chamber 19 on the side of the second axial end 23 of the piston rod 21 and a second chamber 20 on the side of the first end 22.

[0033] The portion of the piston rod 21 of the shock absorber 1 extending from the cylinder 2 is arranged at the top and connected to the vehicle body. The main body 11 of the housing 5 of the shock absorber 1 is arranged at the bottom and connected to the vehicle wheel side.

[0034] The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 moves integrally with the piston rod 21. The stroke of the shock absorber 1's piston rod 21 moving in the direction of increasing the extension from the cylinder 2 is the extension stroke, which extends the full length. The stroke of the shock absorber 1's piston rod 21 moving in the direction of decreasing the extension from the cylinder 2 is the contraction stroke, which shortens the full length. During the extension stroke, the shock absorber 1 moves the piston 18 toward the first chamber 19. During the contraction stroke, the shock absorber 1 moves the piston 18 toward the second chamber 20.

[0035] A rod guide 25 is fitted between the upper openings of the tube 3 and the upper openings of the housing 5. A sealing member 26 is fitted to the housing 5 above the rod guide 25. Both the rod guide 25 and the sealing member 26 are annular. The piston rod 21 is inserted radially inward of the rod guide 25 and the sealing member 26. The piston rod 21 slides axially relative to the rod guide 25 and the sealing member 26. The piston rod 21 extends from the interior of the cylinder 2 to the exterior of the cylinder 2, beyond the sealing member 26.

[0036] The rod guide 25 restricts the radial movement of the piston rod 21 relative to the tube 3 and the housing 5 of the cylinder 2. The piston rod 21 is fitted into the rod guide 25, and the piston 18 is fitted into the tube 3. As a result, the center axis of the piston rod 21 is aligned with the center axis of the tube 3. The rod guide 25 supports the piston rod 21 so that it can move in the axial direction of the piston rod 21. The outer periphery of the sealing component 26 is in close contact with the housing 5. The inner periphery of the sealing component 26 is in close contact with the outer periphery of the piston rod 21. The piston rod 21 slides in the axial direction of the sealing component 26 relative to the sealing component 26. The sealing component 26 prevents the oil L in the tube 3 and the high-pressure gas G and oil L in the storage chamber 7 from leaking to the outside.

[0037] The rod guide 25 has a large diameter portion 28, an intermediate diameter portion 29, and a small diameter portion 30 on its outer circumference. The outer diameter of the large diameter portion 28 is larger than that of the intermediate diameter portion 29. The outer diameter of the intermediate diameter portion 29 is larger than that of the small diameter portion 30. The intermediate diameter portion 29 of the rod guide 25 is positioned below the large diameter portion 28. The small diameter portion 30 of the rod guide 25 is positioned below the intermediate diameter portion 29. The intermediate diameter portion 29 of the rod guide 25 engages with the inner circumference of the upper end of the tube 3. At this point, the upper end of the tube 3 abuts against the large diameter portion 28 in the axial direction of the tube 3. The upper large diameter portion 28 of the rod guide 25 engages with the inner circumference of the upper portion of the main body member 11 of the housing 5.

[0038] A valve body assembly 31 is placed on the bottom member 12 of the housing 5. The valve body assembly 31 is located on the side of the second chamber 20 opposite the piston assembly 17. The valve body assembly 31 includes a seat member 32. The seat member 32 is placed in contact with the upper surface of the bottom member 12 of the housing 5. The seat member 32 is radially positioned relative to the housing 5. The seat member 32 has a large diameter portion 33 and a small diameter portion 34 on its radial outer periphery. The outer diameter of the large diameter portion 33 is larger than that of the small diameter portion 34. The large diameter portion 33 of the seat member 32 is positioned below the small diameter portion 34. The large diameter portion 33 of the seat member 32 is placed on the upper surface of the bottom member 12. The small diameter portion 34 at the top of the seat member 32 engages with the inner periphery of the lower end of the tube 3. At this point, the lower end of the tube 3 abuts the large diameter portion 33 in the axial direction of the tube 3. Thus, the valve body assembly 31 is connected to one axial end of the tube 3.

[0039] A cover 41 is attached to the upper end of the main body 11 of the housing 5. The cover 41 is fitted and fixed to the main body 11. A disk 42 is placed on the sealing member 26. The disk 42 and the sealing member 26 are fixed to the cylinder 2 by being sandwiched between the cover 41 and the rod guide 25. When installing the cover 41, the bottom member 12 of the housing 5 is placed on a table, and the disk 42 is pressed against the sealing member 26 in the axial direction of the housing 5. This causes the disk 42, sealing member 26, rod guide 25, tube 3, seat member 32, and bottom member 12 to abut against each other in the axial direction without any gap. This generates an axial force on the disk 42, sealing member 26, rod guide 25, tube 3, and seat member 32. In this state, the cover 41 is fixed to the main body 11. This generates an axial force on the disk 42, sealing member 26, rod guide 25, tube 3, and seat member 32.

[0040] The piston rod 21 includes a main shaft portion 51 and a mounting shaft portion 52. Both the main shaft portion 51 and the mounting shaft portion 52 are rod-shaped. The outer diameter of the mounting shaft portion 52 is smaller than that of the main shaft portion 51. The mounting shaft portion 52 extends from one axial end of the main shaft portion 51. The central axis of the mounting shaft portion 52 coincides with the central axis of the main shaft portion 51. The entire mounting shaft portion 52 is disposed within the tube 3. The main shaft portion 51 of the piston rod 21 slides axially relative to the rod guide 25 and the sealing member 26, respectively.

[0041] like Figure 2 As shown, the end of the mounting shaft portion 52 of the piston rod 21 opposite the main shaft portion 51 in the axial direction is the first end portion 22. An external thread 54 is formed on the outer periphery of the first end portion 22. The portion of the mounting shaft portion 52 between the main shaft portion 51 and the first end portion 22 in the axial direction of the mounting shaft portion 52 is the fitting shaft portion 55. The outer periphery of the fitting shaft portion 55 is a cylindrical surface.

[0042] The piston assembly 17 , the intervening member 60 , the intervening member 61 , and the relief valve assembly 62 (valve assembly) described above are connected to the mounting shaft portion 52 of the piston rod 21 .

[0043] A through hole 70 is formed in the radial center of the piston 18 of the piston assembly 17. The through hole 70 penetrates the piston 18 in the axial direction of the piston 18. The fitting shaft portion 55 of the piston rod 21 is fitted into the through hole 70 of the piston 18. In the piston 18, a first passage 71 and a second passage 72 are formed at a position radially outside the through hole 70 of the piston 18. The first passage 71 and the second passage 72 penetrate the piston 18 in the axial direction of the piston 18. A plurality of the first passages 71 and the second passages 72 are respectively formed in the piston 18. The first passages 71 and the second passages 72 are alternately arranged in the circumferential direction of the piston 18. Both the first passage 71 and the second passage 72 can connect the first chamber 19 with the second chamber 20.

[0044] The piston assembly 17 has a first damping valve 75 and a second damping valve 76 .

[0045] The first damping valve 75 is a disk valve constructed by stacking multiple annular disks. The first damping valve 75 engages with the engaging shaft portion 55 of the piston rod 21 on its radially inner side. The first damping valve 75 is located axially on the opposite side of the piston rod 21 from the main shaft portion 51 of the piston 18. During the extension stroke of the piston rod 21, the outer peripheral portion of the first damping valve 75 moves away from the piston 18, opening the first passage 71. This allows the oil L to flow from the first chamber 19 to the second chamber 20 via the first passage 71. At this time, the first damping valve 75 suppresses the flow of the oil L, generating a damping force. The first damping valve 75 is located in the first passage 71, suppressing the flow of the oil L generated in the first passage 71 during the extension stroke, generating a damping force. The outer peripheral portion of the first damping valve 75 abuts against the piston 18, closing the first passage 71. A fixed orifice (not shown) is provided between the first damping valve 75 and the piston 18. Even when the outer peripheral portion of the first damping valve 75 contacts the piston 18 , the fixed orifice allows the oil L to flow from the first chamber 19 to the second chamber 20 via the first passage 71 .

[0046] The second damping valve 76 is a disk valve constructed by stacking multiple annular disks. The second damping valve 76 has the mating shaft 55 mated radially inward. The second damping valve 76 is positioned axially between the main shaft 51 and the piston 18. During the extension stroke of the piston rod 21, the outer peripheral portion of the second damping valve 76 moves away from the piston 18, opening the second passage 72. This allows the oil L to flow from the second chamber 20 to the first chamber 19 via the second passage 72. At this time, the second damping valve 76 suppresses the flow of the oil L, generating a damping force. The second damping valve 76 is located in the second passage 72, suppressing the flow of the oil L generated in the second passage 72 during the contraction stroke, generating a damping force. The outer peripheral portion of the second damping valve 76 abuts against the piston 18, closing the second passage 72. A fixed orifice (not shown) is provided between the second damping valve 76 and the piston 18. Even when the outer peripheral portion of the second damping valve 76 contacts the piston 18 , the fixed orifice allows the oil L to flow from the second chamber 20 to the first chamber 19 via the second passage 72 .

[0047] The piston assembly 17 including the piston 18 , the first damping valve 75 , and the second damping valve 76 moves integrally with the piston rod 21 when the piston rod 21 moves in the axial direction of the tube 3 relative to the tube 3 , thereby generating a damping force.

[0048] The interposing member 60 is annular in shape. The interposing shaft portion 55 is interposed radially inwardly of the interposing member 60. The interposing member 60 is positioned on the side of the second damping valve 76 opposite the piston 18 in the axial direction of the piston rod 21. The interposing member 60 abuts against the second damping valve 76. The rigidity of the interposing member 60 is higher than that of the disk constituting the second damping valve 76. The interposing member 60 suppresses excessive deformation of the second damping valve 76.

[0049] The interposing member 61 is annular in shape. The interposing member 61 engages the engaging shaft portion 55 radially inward. The interposing member 61 is positioned on the side of the first damping valve 75 opposite the piston 18 in the axial direction of the piston rod 21. The interposing member 61 abuts against the first damping valve 75. The rigidity of the interposing member 61 is higher than that of the disk constituting the first damping valve 75. The interposing member 61 suppresses excessive deformation of the first damping valve 75.

[0050] The relief valve assembly 62 includes a support piston 81 and a relief valve 82 .

[0051] A through hole 84 is formed in the radial center of the support piston 81. The through hole 84 extends through the support piston 81 in the axial direction. The engaging shaft portion 55 of the piston rod 21 is fitted into the through hole 84 of the support piston 81. A passage hole 85 is formed in the support piston 81 at a position radially outward of the through hole 84. The passage hole 85 extends through the support piston 81 in the axial direction. A plurality of passage holes 85 are formed in the support piston 81. The plurality of passage holes 85 are spaced apart in the circumferential direction of the support piston 81.

[0052] The support piston 81 has a large diameter portion 87 and a small diameter portion 88 on its outer periphery. The outer diameter of the large diameter portion 87 is larger than that of the small diameter portion 88. The small diameter portion 88 of the support piston 81 is provided below the large diameter portion 87.

[0053] The relief valve 82 is a disk valve formed by stacking multiple annular disks. The relief valve 82 has the interlocking shaft portion 55 of the piston rod 21 interlocked with the radially inner side thereof. The relief valve 82 is arranged between the clamping member 61 and the support piston 81 in the axial direction of the piston rod 21. The outer peripheral portion of the relief valve 82 abuts against the support piston 81 and closes the passages in the multiple passage holes 85. The outer peripheral portion of the relief valve 82 leaves the support piston 81 and opens the passages in the multiple passage holes 85. The clamping member 61 abuts against the relief valve 82. The rigidity of the clamping member 61 is higher than the rigidity of the disk constituting the relief valve 82. The clamping member 61 suppresses excessive deformation of the relief valve 82.

[0054] The first end portion 22 of the piston rod 21 protrudes from the support piston 81 toward the side of the piston rod 21 opposite to the relief valve 82 in the axial direction. Furthermore, a nut 91 is screwed into the external thread 54 formed on the outer circumference of the first end portion 22. As a result, at least the inner circumference of each of the intervening member 60, the second damping valve 76, the piston 18, the first damping valve 75, the intervening member 61, the relief valve 82, and the support piston 81 is axially clamped by the main shaft portion 51 and the nut 91.

[0055] The relief valve assembly 62, which includes the support piston 81 and the relief valve 82, is mounted to the mounting shaft portion 52 of the piston rod 21 via a nut 91. Thus, the relief valve assembly 62 is positioned closer to the valve body assembly 31 than the piston assembly 17 of the piston rod 21. The support piston 81 is fixed to the piston rod 21.

[0056] The relief valve assembly 62 is connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17. The relief valve assembly 62 includes a support piston 81 connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17, and a relief valve 82 composed of a plate-like disk disposed in contact with the support piston 81.

[0057] The first cylinder 101 is connected to the support piston 81. The support piston 81 and the first cylinder 101 constitute a bottomed cylindrical cup 100. The cup 100 moves integrally with the piston rod 21.

[0058] The first cylinder 101 is cylindrical. The outer diameter of the first cylinder 101 is smaller than the inner diameter of the tube 3. The first cylinder 101 is arranged radially inward of the tube 3. The small-diameter portion 88 of the lower portion of the support piston 81 is pressed into the inner circumference of the upper end of the first cylinder 101. As a result, the first cylinder 101 is fixed to the support piston 81. At this time, the upper end of the first cylinder 101 abuts against the large-diameter portion 87 of the support piston 81 in the axial direction. In addition, at this time, the center axis of the first cylinder 101 is consistent with the center axis of the tube 3. The first cylinder 101 is arranged in the second chamber 20 with a radial gap between it and the tube 3. The first cylinder 101 is supported by the support piston 81.

[0059] The first cylinder 101 includes a main body portion 111 and an enlarged diameter portion 112 .

[0060] The main body 111 is cylindrical with a constant inner diameter and a constant outer diameter, and is provided from one axial end to the middle portion of the first cylinder 101. One axial end of the main body 111 of the first cylinder 101 is engaged with the small diameter portion 88 of the support piston 81. The other axial end of the main body 111 of the first cylinder 101 extends downward from the support piston 81 from the middle portion thereof.

[0061] The expanded diameter portion 112 is provided at the other axial end of the first cylinder 101, i.e., the lower end. The inner diameter of the expanded diameter portion 112 increases as it approaches the lower end. The outer diameter of the expanded diameter portion 112 increases as it approaches the lower end. The expanded diameter portion 112 expands in the direction away from the main body portion 111 in the axial direction of the first cylinder 101.

[0062] The first cylinder 101 of the cup-shaped member 100 is open downward. The first cylinder 101 is provided with a groove 116 extending in the axial direction of the first cylinder 101 on the inner circumference of one axial end side thereof. The groove 116 is provided on the inner circumference of the lower end side of the first cylinder 101. The groove 116 is recessed from the inner circumferential surface of the first cylinder 101 toward the radial outer side of the first cylinder 101. The groove 116 extends from the expanded diameter portion 112 to the lower portion of the main body 111. On the first cylinder 101, a plurality of grooves 116 are provided at equal intervals in the circumferential direction of the first cylinder 101. The lengths of the plurality of grooves 116 from the lower end of the first cylinder 101 are different. In other words, the lengths of the plurality of grooves 116 in the axial direction of the first cylinder 101 are different.

[0063] The first cylinder 101 is connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17 via the support piston 81 of the relief valve assembly 62. The relief valve assembly 62 is arranged in the second chamber 20 and connected to the piston rod 21.

[0064] In addition to the seat member 32, the valve body assembly 31 includes a disk valve 122, a disk valve 123, a bolt 124, and a nut 125. The bolt 124 includes a shaft 126 and a head 127. The outer diameter of the shaft 126 is smaller than that of the head 127. The shaft 126 has an external thread 128 formed on its outer circumference on the axial side opposite to the head 127.

[0065] Disk valve 122 is located below seat member 32. Disk valve 123 is located above seat member 32. The shaft 126 of bolt 124 is inserted from below into disk valve 122, seat member 32, and disk valve 123. In this state, nut 125 is screwed into the external thread 128 of bolt 124. Thus, bolt 124 and nut 125 secure disk valve 122 and disk valve 123 to seat member 32.

[0066] The seat member 32 is annular in shape. The seat member 32 includes a base portion 131 and a protrusion 132. The base portion 131 is disk-shaped. A through-hole 133 is formed in the radial center of the base portion 131. The through-hole 133 extends through the base portion 131 in the axial direction of the seat member 32. The shaft portion 126 of the bolt 124 is inserted through the through-hole 133 of the seat member 32. A passage hole 134 and a passage hole 135 are formed in the seat member 32 at positions radially outward of the through-hole 133. The passage holes 134 and 135 extend through the base portion 131 in the axial direction of the seat member 32. The passage hole 135 is located radially outward of the passage hole 134 in the seat member 32. A plurality of passage holes 134 and a plurality of passage holes 135 are formed in the seat member 32 at intervals in the circumferential direction.

[0067] The protrusion 132 protrudes downward from the outer periphery of the base portion 131. The protrusion 132 is positioned radially outward of the base portion 131, relative to the passage hole 135. The protrusion 132 of the seat member 32 abuts against the bottom member 12 of the housing 5. A passage groove 136 is formed in the protrusion 132, extending radially through the protrusion 132. The seat member 32 is provided with a plurality of passage grooves 136 at equal intervals along its circumference. This allows communication between the seat member 32 and the bottom member 12 of the housing 5, as well as between the main body member 11 of the housing 5 and the tube 3. Consequently, the space between the seat member 32 and the bottom member 12 of the housing 5 also defines the storage chamber 7. The seat member 32 divides the second chamber 20 and the storage chamber 7.

[0068] The shock absorber 1 includes a base adapter 141 , a second cylinder 142 (support member), and a divided piston 143 .

[0069] The base adapter 141 is annular and includes a main plate portion 151 , a press-fit portion 152 , and a leg portion 153 .

[0070] The main plate portion 151 is in the shape of a circular plate. The press-in portion 152 is provided at one axial end of the base adapter 141. The press-in portion 152 protrudes upward from the upper surface of the main plate portion 151. The press-in portion 152 is in the shape of a cylinder. The outer diameter of the press-in portion 152 is smaller than the outer diameter of the main plate portion 151. A through hole 161 is formed in the radial center portion of the main plate portion 151 and the press-in portion 152, which penetrates them in the axial direction. Therefore, the main plate portion 151 is in the shape of a circular plate with a hole, and the press-in portion 152 is in the shape of a cylinder.

[0071] The leg portion 153 is provided at the end portion of the base adapter 141 opposite the press-fit portion 152 in the axial direction. The leg portion 153 protrudes downward from the lower surface of the outer circumference of the main plate portion 151. The leg portion 153 is cylindrical in shape. It is positioned radially outward of the main plate portion 151 relative to the through-hole 161. The radially inner circumference of the leg portion 153 increases in diameter as it moves away from the main plate portion 151 in the axial direction of the base adapter 141. In other words, the inner circumference of the leg portion 153 increases in diameter as it moves away from the main plate portion 151 in the axial direction.

[0072] A connecting groove 162 is formed on the outer periphery of the main plate portion 151 and the leg portion 153, penetrating the main plate portion 151 and the leg portion 153 in the axial direction of the base adapter 141. Figure 3 As shown, the communication groove 162 opens radially outward from the base adapter 141. The communication groove 162 extends radially through the leg portion 153. Therefore, the communication groove 162 opens on the upper surface of the main plate portion 151, the outer circumference of the main plate portion 151, the outer circumference of the leg portion 153, the lower surface of the leg portion 153, and the inner circumference of the leg portion 153. The base adapter 141 is provided with a plurality of communication grooves 162 at equal intervals around the circumference of the base adapter 141.

[0073] like Figure 2 As shown, the legs 153 of the base adapter 141 are press-fitted and secured to the inner circumference of the pipe 3. At this point, the lower ends of the legs 153 of the base adapter 141 abut against the upper surface of the outer circumference of the base portion 131 of the seat member 32. Furthermore, the base adapter 141 is prevented from contacting the bolts 124 and nuts 125 of the valve body assembly 31 by the through-holes 161. Furthermore, the legs 153 of the base adapter 141 radially surround the disk valve 123 of the valve body assembly 31. In other words, the legs 153 are positioned radially outward from the disk valve 123. The base adapter 141, abutting the valve body assembly 31, is positioned between the first cylinder 101 and the valve body assembly 31. The base adapter 141 is supported axially by the valve body assembly 31 and radially by the pipe 3.

[0074] The second cylinder 142 is cylindrical. Its outer diameter is smaller than the inner diameter of the main body 111 of the first cylinder 101. The inner circumference of the lower end of the second cylinder 142 is press-fitted into the press-fit portion 152 of the base adapter 141. At this point, the upper surface of the main plate 151 abuts the lower end of the second cylinder 142. This secures the second cylinder 142 to the base adapter 141. Thus, the second cylinder 142 is press-fitted and secured to the base adapter 141. The second cylinder 142 extends from the base adapter 141 toward the side of the base adapter 141 axially opposite the valve body assembly 31. The base adapter 141 and the second cylinder 142 are disposed in the second chamber 20. The second cylinder 142 is supported radially by the base adapter 141 and axially by the valve body assembly 31 via the base adapter 141. The communicating groove 162 of the base adapter 141 is formed radially outward of the second cylinder 142 on the main plate 151.

[0075] As described above, the base adapter 141 has a press-fit portion 152 at one axial end thereof, which is press-fitted into the second cylinder 142. The base adapter 141 has a leg portion 153 at the other axial end thereof, which is mounted on the valve body assembly 31. The inner circumference of the leg portion 153 increases in diameter as it approaches the valve body assembly 31 in the axial direction of the base adapter 141.

[0076] The dividing piston 143 is attached to an end portion of the second cylinder 142 on the opposite side from the base adapter 141 in the axial direction, that is, an upper end portion of the second cylinder 142 .

[0077] The dividing piston 143 includes a base member 171 , a locking member 172 , and a movable ring 173 (movable member).

[0078] The base member 171 includes a main body portion 181 , a flange portion 182 , and a cylindrical portion 183 .

[0079] The main body 181 is cylindrical.

[0080] The flange 182 extends radially outward from one axial end of the main body 181. The flange 182 is annular and extends around the entire circumference of the main body 181. The outer diameter of the flange 182 is smaller than the inner diameter of the main body 111 of the first cylinder 101.

[0081] The main body 181 has an axial groove 191 extending in the axial direction of the main body 181 formed on the outer periphery of the portion excluding the flange 182. The main body 181 has a plurality of axial grooves 191 formed therein at intervals in the circumferential direction.

[0082] The flange portion 182 has radial grooves 192 formed on the axial side of the flange portion 182, extending radially through the flange portion 182. The flange portion 182 has multiple radial grooves 192 formed at intervals in the circumferential direction. The flange portion 182 has the same number of radial grooves 192 as the axial grooves 191 of the main body portion 181. Each of the multiple radial grooves 192 is aligned in phase with the corresponding axial groove 191 in the circumferential direction of the base member 171.

[0083] The cylindrical portion 183 is cylindrical in shape, with an outer diameter smaller than that of the flange portion 182. An axial groove 193 extending in the axial direction is formed on the outer periphery of the cylindrical portion 183. A plurality of axial grooves 193 are formed in the cylindrical portion 183 at intervals along its circumference. In the axial direction of the cylindrical portion 183, the axial grooves 193 are formed so as to diverge from the end of the cylindrical portion 183 on the axial side of the flange portion 182 toward the side opposite the flange portion 182.

[0084] The locking member 172 includes a fitting portion 201 and a flange portion 202 .

[0085] The fitting portion 201 is cylindrical.

[0086] The flange portion 202 extends from one axial end side of the fitting portion 201 toward the radially outer side of the fitting portion 201. The flange portion 202 has an annular shape extending around the entire circumference of the fitting portion 201. The outer diameter of the flange portion 202 is smaller than the inner diameter of the main body portion 111 of the first cylinder 101. A passage hole 205 is formed in the flange portion 202, extending through the flange portion 202 in the axial direction. A plurality of passage holes 205 are formed in the flange portion 202 at intervals in the circumferential direction.

[0087] The movable ring 173 is annular. A portion of the movable ring 173 is broken in the circumferential direction, creating a circumferential gap, allowing it to expand and contract in the radial direction. The inner diameter of the movable ring 173 in its natural state is smaller than the outer diameter of the flange portion 182 of the base member 171 and the outer diameter of the flange portion 202 of the locking member 172. The outer diameter of the movable ring 173 in its natural state is less than the maximum inner diameter of the expanded diameter portion 112 of the first cylinder 101 and greater than the inner diameter of the main body 111. The movable ring 173 is reduced in diameter, and its outer diameter becomes equal to the inner diameter of the main body 111 of the first cylinder 101. In this state, the inner diameter of the movable ring 173 is larger than the outer diameter of the cylindrical portion 183 of the base member 171. Furthermore, in this state, the circumferential gap of the movable ring 173 is not zero. The axial length of the movable ring 173 is shorter than the axial length of the cylindrical portion 183 of the base member 171.

[0088] The base member 171 that divides the piston 143 is fixed to the second cylinder 142 by fitting the inner circumference of the main body 181 with the upper end of the second cylinder 142. In other words, the base member 171 is fitted with the inner circumference on the opposite side of the main body 181 from the base adapter 141 in the axial direction of the second cylinder 142. At this time, the flange 182 of the base member 171 abuts the second cylinder 142 in the axial direction of the base member 171. The axial grooves 191 and radial grooves 192 of the base member 171 fixed to the second cylinder 142 thus form a communication path 208 that connects the radially inner and radially outer sides of the second cylinder 142.

[0089] The partitioning piston 143 is thus fixed to the second cylinder 142, and the movable ring 173 is placed on the upper side of the flange portion 182 of the base member 171. In other words, the movable ring 173 is arranged on the axially opposite side of the flange portion 182 from the second cylinder 142. At this time, the cylindrical portion 183 of the base member 171 is inserted radially inward of the movable ring 173.

[0090] The locking member 172 of the partition piston 143 is pressed into the inner circumference of the cylindrical portion 183 of the base member 171 at the fitting portion 201, thereby being fixed to the base member 171. At this point, the flange 202 of the locking member 172 abuts against the end of the cylindrical portion 183 of the base member 171 opposite the flange 182 in the axial direction. In this state, the flange 202 of the locking member 172 prevents the movable ring 173 from falling off the cylindrical portion 83. As a result, the movable ring 173 is axially clamped between the flange 182 of the base member 171 and the flange 202 of the locking member 172.

[0091] The movable ring 173 is movable in the axial direction between the flange portions 182 and 202. When the movable ring 173 moves axially away from the flange portion 182, it opens a passage 210. This passage 210 is composed of the passages within the plurality of passage holes 205 of the locking member 172, the passage between the movable ring 173 and the cylindrical portion 183 of the base member 171, the passages within the plurality of axial grooves 193 of the cylindrical portion 183, and the passage between the movable ring 173 and the flange portion 182. When the movable ring 173 abuts the flange portion 182 in the axial direction, it closes the passage 210.

[0092] The partitioning piston 143 is supported on the bottom member 12 of the tube 3 via the second cylinder 142, the base adapter 141, and the seat member 32 of the valve body assembly 31. In other words, the second cylinder 142, which has a smaller diameter than the first cylinder 101, is installed in the valve body assembly 31 via the base adapter 141 and supports the partitioning piston 143. The second cylinder 142 and the base adapter 141 constitute the partitioning piston support body 211, which is placed on the valve body assembly 31 and supports the partitioning piston 143. The partitioning piston 143 and the partitioning piston support body 211 are installed in the second chamber 20.

[0093] The area surrounded by the valve body assembly 31, the base adapter 141, the second cylinder 142, and the partitioning piston 143 forms the second cylinder chamber 213. The second cylinder chamber 213 communicates with the portion of the second chamber 20 between the tube 3 and the first cylinder 101, and the portion of the second chamber 20 between the tube 3 and the second cylinder 142, via a passage in the communication groove 162 of the base adapter 141. The second cylinder chamber 213 constitutes a portion of the second chamber 20. In other words, the communication groove 162 is provided in the main plate portion 151 and the leg portion 153 of the base adapter 141. This communication groove 162 forms the second cylinder chamber 213, which is part of the second chamber 20, in the second cylinder 142. The communication passage 208 between the partitioning piston 143 and the second cylinder 142 connects the second cylinder chamber 213 within the second cylinder 142 with the outside of the second cylinder 142. If air is present in the second cylinder chamber 213 within the second cylinder 142, the communication passage 208 allows the air to flow out of the second cylinder 142.

[0094] In the valve body assembly 31, the plurality of passage holes 134 allow the oil L to flow between the second chamber 20 including the second cylinder chamber 213 and the reservoir chamber 7. In the valve body assembly 31, the plurality of passage holes 135 allow the oil L to flow between the reservoir chamber 7 and the second chamber 20 including the second cylinder chamber 213.

[0095] The disk valve 122 on the reservoir chamber 7 side allows the oil L to flow from the second chamber 20 including the second cylinder chamber 213 to the reservoir chamber 7 via the passage hole 134. On the other hand, the disk valve 122 restricts the flow of the oil L from the reservoir chamber 7 to the second chamber 20 via the passage hole 134. The disk valve 122 opens during the contraction stroke of the shock absorber 1, primarily allowing the oil L to flow from the second chamber 20 to the reservoir chamber 7 and generate a damping force.

[0096] The disk valve 123 on the second cylinder chamber 213 side allows the flow of oil L from the reservoir chamber 7 to the second chamber 20 via the passage hole 135. On the other hand, the disk valve 123 restricts the flow of oil L from the second chamber 20 to the reservoir chamber 7 via the passage hole 135. The disk valve 123 maintains constant communication between the second chamber 20 and the passage hole 134. During the extension stroke of the shock absorber 1, the disk valve 123 opens, allowing the oil L to flow from the reservoir chamber 7 to the second chamber 20 and generate a damping force. Alternatively, the disk valve 123 can be configured as a suction valve that allows the oil L to flow from the reservoir chamber 7 to the second chamber 20 without generating substantial damping force.

[0097] The dividing piston 143 enters the first cylinder 101 from below through the opening at the lower end of the first cylinder 101 and retracts downward.

[0098] Here, when piston rod 21 is in a first predetermined range where cup 100 including first cylinder 101 is positioned above partition piston 143 and cup 100 and partition piston 143 are not fitted together, the entire interior of cup 100 becomes second chamber 20 .

[0099] From this state, during the retraction stroke, the piston rod 21 moves to a second predetermined range closer to the base adapter 141 than the first predetermined range. Then, the cup-shaped member 100, which moves integrally with the piston rod 21, causes the movable ring 173 of the partitioning piston 143 to enter the expanded diameter portion 112 of the first cylinder 101 in such a manner as to cover the partitioning piston 143, and then the movable ring 173 is fitted into the main body 111 of the first cylinder 101. In the initial stage of this fitting, the movable ring 173 is subjected to friction with the first cylinder 101 in contact, as shown in FIG. Figure 2 As shown, the movable ring 173 is pressed against the flange portion 182 of the base member 171 to block the passage 210. In the subsequent contraction stroke, the movable ring 173 slides in the first cylinder 101 so as to approach the support piston 81 while being pressed against the flange portion 182 to block the passage 210.

[0100] When the first cylinder 101 is engaged with the movable ring 173 of the partitioning piston 143, the second chamber 20 is divided into a first cylinder inner chamber 214 (partitioning chamber) within the first cylinder 101 and a cylinder outer chamber 215 outside the first cylinder 101. The first cylinder inner chamber 214 is the portion between the relief valve assembly 62 and the partitioning piston 143 in the first cylinder 101. The cylinder outer chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. The cylinder outer chamber 215 includes the portion between the cup 100 and the tube 3, the portion between the second cylinder 142 and the tube 3, the portion between the first cylinder 101 and the second cylinder 142, and the second cylinder inner chamber 213. The passage 210 of the partitioning piston 143 connects the cylinder outer chamber 215 with the first cylinder inner chamber 214, and the movable ring 173 can open and close this passage 210.

[0101] During the retraction stroke within the second predetermined range, as described above, the cup 100 and piston rod 21 move toward the base adapter 141, with the movable ring 173 abutting against the flange 182 and blocking the passage 210. At the upper portion of the second predetermined range, the movable ring 173 is positioned within the plurality of grooves 116 provided in the first cylinder 101, and the oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the passages within the plurality of grooves 116. At this point, as the cup 100 approaches the base adapter 141, the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 decreases, ultimately reaching zero. Consequently, the damping force of the cup 100 and the partitioned piston 143, including the first cylinder 101, gradually increases. In the subsequent contraction stroke, the movable ring 173 slides in the first cylinder 101 close to the support piston 81 while being fitted in the main body 111 and most closely blocking the passage 210. In other words, the movable ring 173 blocks the passage 210 when the piston assembly 17 moves toward the second chamber 20.

[0102] The relief valve assembly 62, the first cylinder 101 connected to the relief valve assembly 62, and the partitioning piston 143 constitute a damping force increasing mechanism 221 that adds damping force to the damping force generated by the piston assembly 17 when the piston assembly 17 moves toward the second chamber 20. In other words, the damping force increasing mechanism 221 includes the relief valve assembly 62 connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17, and the first cylinder 101 connected to the relief valve assembly 62. The damping force increasing mechanism 221 includes the first cylinder 101 connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17, and the partitioning piston 143 that enters the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20, forming a first cylinder inner chamber 214 within the first cylinder 101.

[0103] Furthermore, during the retraction stroke within the second predetermined range, as described above, with the partitioning piston 143 blocking the passage 210, the cup 100 moves toward the base adapter 141. At this time, the relief valve 82 opens based on the movement speed of the piston rod 21, piston 18, and support piston 81 relative to the tube 3, i.e., the piston velocity. Consequently, the oil L flows from the first cylinder chamber 214 to the cylinder outer chamber 215 via the passages within the plurality of passage holes 85. Consequently, the relief valve 82 suppresses an excessive increase in pressure within the first cylinder chamber 214. While suppressing the damping force generated by the flow of the oil L through the passages within the plurality of passage holes 85 during the retraction stroke, the relief valve 82 allows the oil L to flow from the first cylinder chamber 214 to the cylinder outer chamber 215. The relief valve 82 is more rigid than the second damping valve 76 and is less likely to open. Therefore, the relief valve 82 opens after the second damping valve 76, generating a higher damping force than the second damping valve 76.

[0104] During the extension stroke within the second predetermined range, the cup 100 and the piston rod 21 move together in a direction away from the base adapter 141. Figure 4 As shown, movable ring 173, which divides piston 143, separates axially from flange 182 due to friction with first cylinder 101 and abuts against flange 202, thereby opening passage 210. In other words, movable ring 173 opens passage 210 when piston assembly 17 moves toward first chamber 19. During the subsequent extension stroke, cup 100 moves away from base adapter 141 while maintaining movable ring 173 opening passage 210. As cup 100 moves away from base adapter 141, oil L flows from the portion between first cylinder 101 and second cylinder 142 in outer cylinder chamber 215 via passage 210 into first cylinder inner chamber 214. This reduces the damping force of piston rod 21 in the extension direction.

[0105] During the extension stroke, starting from the position where movable ring 173 is located closer to the support piston 81 than all grooves 116 in first cylinder 101, when cup 100 separates support piston 81 a predetermined distance from movable ring 173, movable ring 173 is positioned within groove 116 provided in first cylinder 101, opening groove 116 into first cylinder inner chamber 214. Consequently, in addition to flowing through passage 210, oil L also flows from outer cylinder chamber 215 into first cylinder inner chamber 214 via the passage within groove 116, reducing the damping force exerted on piston rod 21 in the extension direction. At this point, the further away from base adapter 141 cup 100 is, the greater the number of grooves 116 through which oil L flows from outer cylinder chamber 215 into first cylinder inner chamber 214. Consequently, the damping force exerted on piston rod 21 in the extension direction is gradually reduced.

[0106] like Figure 1 As shown, the third cylinder 231 is connected to the small-diameter portion 30 of the rod guide 25. The third cylinder 231 is cylindrical and is positioned radially inward of the tube 3. The inner circumference of the third cylinder 231's upper end engages with the small-diameter portion 30 of the rod guide 25, securing it to the rod guide 25. The upper end of the third cylinder 231 axially abuts the intermediate-diameter portion 29 of the rod guide 25. Furthermore, the central axis of the third cylinder 231 coincides with the central axis of the tube 3. The third cylinder 231 is positioned in the first chamber 19 with a radial gap between it and the tube 3.

[0107] The third cylinder 231 includes a main body portion 241 and an enlarged diameter portion 242 .

[0108] The main body 241 is cylindrical with a constant inner diameter and a constant outer diameter, and is provided from one axial end to the middle portion of the third cylinder 231. One axial end of the main body 241 of the third cylinder 231 is engaged with the small diameter portion 30 of the rod guide 25. The other end of the third cylinder 231 extends downward from the axial middle portion of the main body 241.

[0109] The expanded diameter portion 242 is provided at the other axial end of the third cylinder 231, i.e., the lower end. The inner diameter of the expanded diameter portion 242 increases as it approaches the lower end. The outer diameter of the expanded diameter portion 242 increases as it approaches the lower end. The expanded diameter portion 242 expands in the axial direction away from the main body portion 241 of the third cylinder 231. The third cylinder 231 opens downward.

[0110] The third cylinder 231 is provided with a groove 246 extending in the axial direction of the third cylinder 231 on the inner circumference of one axial end side thereof. The groove 246 is provided on the inner circumference of the lower end side of the third cylinder 231. The groove 246 is recessed from the inner circumferential surface of the third cylinder 231 toward the radially outer side of the third cylinder 231. The groove 246 extends from the expanded diameter portion 242 to the lower portion of the main body portion 241. On the third cylinder 231, a plurality of grooves 246 are provided at equal intervals in the circumferential direction of the third cylinder 231. The lengths of the plurality of grooves 246 from the lower end of the third cylinder 231 are different. In other words, the lengths of the plurality of grooves 246 in the axial direction of the third cylinder 231 are different.

[0111] The main shaft portion 51 of the piston rod 21 is provided with a damping piston 250 . The damping piston 250 includes a first stopper member 251 , a first retaining ring 252 , a second stopper member 253 , a second retaining ring 254 , a ring member 255 , and a damping member 256 .

[0112] The first stopper 251 , the first retaining ring 252 , the second stopper 253 , the second retaining ring 254 , the ring member 255 , and the buffer member 256 are all annular and penetrate the main shaft 51 on the inner side.

[0113] The first retaining ring 252 is positioned in the axial direction of the main shaft portion 51 and is attached to the main shaft portion 51 .

[0114] The first stopper 251 is arranged on the rod guide 25 side of the first retaining ring 252 in the axial direction of the piston rod 21. The first stopper 251 is restricted from moving away from the rod guide 25 in the axial direction of the piston rod 21 by contact with the first retaining ring 252.

[0115] The second stopper member 253 includes a cylindrical portion 261 and a flange portion 262 .

[0116] The cylindrical portion 261 has a cylindrical shape.

[0117] The flange portion 262 extends from one axial end side of the cylindrical portion 261 toward the radially outer side of the cylindrical portion 261. The flange portion 262 has an annular shape extending over the entire circumference of the cylindrical portion 261. The outer diameter of the flange portion 262 is smaller than the inner diameter of the main body 241 of the third cylinder 231. A radial groove 271 is formed on the axial side of the cylindrical portion 261 of the flange portion 262, extending radially through the flange portion 262. A plurality of radial grooves 271 are formed at intervals around the circumference of the flange portion 262.

[0118] The second retaining ring 254 is positioned and attached to the main shaft portion 51 in the axial direction of the main shaft portion 51 at a position closer to the rod guide 25 than the first stopper member 251 .

[0119] The second stopper 253 is disposed between the second retaining ring 254 and the first stopper 251 in the axial direction of the piston rod 21. The second stopper 253 is provided on the main shaft 51 such that the flange 262 is further away from the first stopper 251 than the cylindrical portion 261 in the axial direction of the piston rod 21. The second stopper 253 abuts against both the second retaining ring 254 and the first stopper 251, thereby restricting axial bidirectional movement of the piston rod 21.

[0120] The ring member 255 is annular. The outer diameter of the ring member 255 is equal to the inner diameter of the main body 241 of the third cylinder 231. The inner diameter of the ring member 255 is larger than the outer diameter of the cylindrical portion 261 of the second stopper member 253, and smaller than the outer diameters of the flange portion 262 of the second stopper member 253 and the outer diameter of the first stopper member 251. The axial length of the ring member 255 is shorter than the length obtained by subtracting the axial length of the flange portion 262 from the axial length of the cylindrical portion 261 of the second stopper member 253. This allows the ring member 255 to move axially between the flange portion 262 of the second stopper member 253 and the first stopper member 251. When the annular member 255 moves away from the first stopper 251 in the axial direction, the passage 272 is opened. The passage 272 is composed of the passage in the radial groove 271 of the second stopper 253, the passage between the annular member 255 and the cylindrical portion 261 of the second stopper 253, and the passage between the movable ring 173 and the first stopper 251. When the annular member 255 abuts the first stopper 251 in the axial direction, the passage 272 is blocked.

[0121] The buffer member 256 is an elastic member and is arranged on the rod guide 25 side of the second stopper member 253 and the second retaining ring 254 in the axial direction of the piston rod 21 .

[0122] The buffer piston 250 enters the third cylinder 231 from below through the lower end opening of the third cylinder 231 and exits downward.

[0123] Here, when the piston rod 21 is in the first predetermined range where the ring member 255 of the cushion piston 250 is arranged below the third cylinder 231 and the ring member 255 is not fitted into the third cylinder 231 , the entire interior of the third cylinder 231 becomes the first chamber 19 .

[0124] From this position, during the extension stroke, the piston rod 21 moves to a third predetermined range, closer to the rod guide 25 than the first predetermined range. Consequently, the cushion piston 250, which moves integrally with the piston rod 21, engages within the main body 241 of the third cylinder 231 after the ring member 255 enters the expanded diameter portion 242 of the third cylinder 231. Initially, the ring member 255 is pressed against the first stopper 251 by friction with the contacting third cylinder 231. As a result, the ring member 255 axially abuts the first stopper 251, blocking the passage 272. During the subsequent extension stroke, the ring member 255 slides within the third cylinder 231, approaching the rod guide 25 while blocking the passage 272.

[0125] During the extension stroke within the third predetermined range, as described above, with the annular member 255 blocking the passage 272, the damping piston 250 moves toward the rod guide 25 along with the piston rod 21. At the lower portion of the third predetermined range, the annular member 255 is positioned within the plurality of grooves 246 provided in the third cylinder 231, allowing the oil L to flow through the grooves 246. As the damping piston 250 approaches the rod guide 25, the number of open grooves 246 decreases, ultimately reaching zero. Consequently, the damping force generated by the third cylinder 231 and the damping piston 250 increases in stages.

[0126] At the upper limit position of the third predetermined range, the damping piston 250 brings the damping member 256 into contact with the rod guide 25 , elastically deforming the damping member 256 , thereby alleviating the impact of the collision with the rod guide 25 .

[0127] During the retraction stroke within the third predetermined range, with the ring member 255 of the damping piston 250 engaged within the third cylinder 231, the damping piston 250 and the piston rod 21 move together in a direction away from the rod guide 25. This action causes the ring member 255 of the damping piston 250 to axially separate from the first stopper 251 due to friction with the third cylinder 231, thereby opening the passage 272. During the subsequent extension stroke, the damping piston 250 moves away from the rod guide 25, maintaining the ring member 255 opening the passage 272. As the damping piston 250 moves away from the rod guide 25, oil L flows through the passage 272. This reduces the damping force of the piston rod 21 in the retraction direction.

[0128] The damping piston 250, starting with the ring member 255 positioned closer to the rod guide 25 than all the grooves 246 in the third cylinder 231, opens the grooves 246 in the third cylinder 231 when the ring member 255 is moved a predetermined distance away from the rod guide 25 during the retraction stroke. This opens the grooves 246 in the third cylinder 231. This opens the grooves 246 in addition to the oil L flowing through the passage 272, reducing the damping force on the piston rod 21 in the retraction direction. At this point, the further the damping piston 250 moves away from the rod guide 25, the greater the number of grooves 246 through which the oil L flows. This gradually reduces the damping force on the piston rod 21 in the retraction direction.

[0129] Next, the main operation of the shock absorber 1 will be described.

[0130] "The piston rod 21 is in the middle of the first predetermined range of contraction stroke in the axial direction of the tube 3"

[0131] {First speed region where the piston speed is slower than the first predetermined value}

[0132] In the first speed range of the contraction stroke, the oil L from the second chamber 20 flows from the second passage 72 in the piston assembly 17 through a fixed orifice (not shown) between the second damping valve 76 and the piston 18 to the first chamber 19. Therefore, in the first speed range of the contraction stroke, a damping force having an orifice characteristic (damping force is substantially proportional to the square of the piston speed) is generated.

[0133] {Second speed region where the piston speed is greater than or equal to the first predetermined value}

[0134] In the second speed range of the contraction stroke, the oil L from the second chamber 20 opens the second damping valve 76 in the piston assembly 17 through the second passage 72 and flows into the first chamber 19. Therefore, in the second speed range of the contraction stroke, a damping force is generated based on the valve characteristics of the second damping valve 76 (the damping force is substantially proportional to the piston speed).

[0135] "The piston rod 21 is within the first predetermined range of extension stroke"

[0136] {Third speed region where the piston speed is slower than the second predetermined value}

[0137] In the third speed range of the extension stroke, the oil L from the first chamber 19 flows from the first passage 71 in the piston assembly 17 through a fixed orifice (not shown) between the first damping valve 75 and the piston 18 to the second chamber 20. Therefore, in the third speed range of the extension stroke, a damping force characteristic of the orifice is generated.

[0138] {Fourth speed region where the piston speed is greater than or equal to the second predetermined value}

[0139] In the fourth speed range of the extension stroke, the oil L from the first chamber 19 flows from the first passage 71 in the piston assembly 17 to open the first damping valve 75 and into the second chamber 20. Therefore, in the fourth speed range of the extension stroke, a damping force corresponding to the valve characteristic of the first damping valve 75 is generated.

[0140] "The piston rod 21 is located within a second predetermined range below the first predetermined range in the axial direction of the tube 3"

[0141] During this contraction stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Furthermore, the cup 100 of the damping force increasing mechanism 221 moves in the axial direction of the tube 3 toward the base adapter 141, causing the movable ring 173 of the partitioning piston 143 to fit into the first cylinder 101. Initially, the movable ring 173 is pressed against the flange 182, blocking the passage 210.

[0142] In this state, the cup 100 moves toward the base adapter 141. Consequently, the oil L in the first cylinder inner chamber 214 is throttled by the multiple grooves 116 provided in the first cylinder 101 and flows toward the outer cylinder chamber 215. As a result, the damping force generated by the damping force increasing mechanism 221 increases. At this point, as the cup 100 approaches the base adapter 141, the number of grooves 116 that allow the oil L to flow from the first cylinder inner chamber 214 to the outer cylinder chamber 215 decreases, ultimately reaching zero. As a result, the damping force generated by the damping force increasing mechanism 221 gradually increases, and the damping force relative to the retraction direction of the piston rod 21 gradually increases. Thus, the amount of damping force generated by the damping force increasing mechanism 221 increases in addition to the damping force generated by the piston assembly 17. Here, at the position where the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 is zero, the movable ring 173 engages with the main body 111 of the first cylinder 101, thereby fully blocking the passage 210. Therefore, during the contraction stroke after the movable ring 173 has reduced the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 to zero, the oil L flowing from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the space between the first cylinder 101 and the partition piston 143 is throttled to the maximum extent. Consequently, the damping force is further increased.

[0143] Here, when the cup 100 moves toward the base adapter 141, the relief valve 82 of the relief valve assembly 62 opens according to the piston speed. As a result, the oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages within the plurality of passage holes 85. This suppresses an excessive increase in the pressure in the first cylinder inner chamber 214.

[0144] "The piston rod 21 is within the second predetermined range of extension stroke"

[0145] In this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. On this basis, the cup 100 of the damping force increasing mechanism 221 moves in the axial direction of the tube 3 in a direction away from the base adapter 141. Figure 4 As shown, the movable ring 173 opens the passage 210 .

[0146] With passage 210 thus open, cup 100 moves away from base adapter 141. Consequently, oil L in outer cylinder chamber 215 flows from between first cylinder 101 and second cylinder 142 to first cylinder inner chamber 214 via passage 210. When movable ring 173 is positioned farther from base adapter 141 than all grooves 116 provided in first cylinder 101, oil L flows from outer cylinder chamber 215 to first cylinder inner chamber 214 via passages within grooves 116 in addition to flow through passage 210. At this point, the further cup 100 moves away from base adapter 141, the greater the number of grooves 116 that allow oil L to flow from outer cylinder chamber 215 to first cylinder inner chamber 214. This gradually reduces the damping force on the extensional movement of piston rod 21.

[0147] "The piston rod 21 is in the extension stroke of the third predetermined range above the first predetermined range in the axial direction of the tube 3"

[0148] In this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Figure 1 The illustrated damping piston 250 moves in the axial direction of the tube 3 toward the rod guide 25, and the ring member 255 is fitted into the third cylinder 231. Initially, the ring member 255 blocks the passage 272.

[0149] With passage 272 thus blocked, the damping piston 250 moves toward the rod guide 25. Consequently, the oil L within the third cylinder 231 is throttled by the multiple grooves 246 provided in the third cylinder 231, flowing out of the third cylinder 231. Consequently, the damping force generated by the third cylinder 231 and the damping piston 250 increases. As the damping piston 250 approaches the rod guide 25, the number of grooves 246 through which the oil L flows decreases, eventually reaching zero. As a result, the damping force generated gradually increases, and the damping force relative to the extension direction of the piston rod 21 gradually increases. The damping force generated by the damping piston 250 and the third cylinder 231 increases relative to the damping force generated by the piston assembly 17.

[0150] "The piston rod 21 is in the retraction stroke of the third predetermined range"

[0151] In this contraction stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. In addition, the cushioning piston 250 moves in a direction away from the rod guide 25. In this manner, the ring member 255 opens the passage 272 in the initial stage.

[0152] With passage 272 thus open, the damping piston 250 moves away from the rod guide 25. Consequently, the oil L flows from outside the third cylinder 231 into the third cylinder 231 via passage 272. When the ring member 255 of the damping piston 250 is positioned closer to the rod guide 25 than all the grooves 246 provided in the third cylinder 231, the oil L flows from outside the third cylinder 231 into the third cylinder 231 via the grooves 246 provided in the third cylinder 231, in addition to flowing through passage 272, the oil L also flows from outside the third cylinder 231 into the third cylinder 231 via the grooves 246. At this point, the farther the damping piston 250 moves from the rod guide 25, the greater the number of grooves 246 through which the oil L flows. This gradually reduces the damping force against the contraction movement of the piston rod 21.

[0153] The specification of the aforementioned U.S. Patent No. 10107352 discloses a shock absorber that increases the damping force when the piston rod reaches a specified range on the limit side during the contraction stroke when the piston rod is pressed into the tube. The shock absorber comprises a cup-shaped insert provided in the valve body assembly, a secondary rod mounted on the main piston rod, and a secondary piston assembly mounted on the secondary rod. Furthermore, by allowing the secondary piston assembly to enter the insert, a partition chamber is formed in the insert, which suppresses the oil discharged from the partition chamber, thereby increasing the damping force. The shock absorber has a complex structure in which a secondary rod is mounted on the main piston rod, and a secondary piston assembly is mounted on the secondary rod. Therefore, the cost of the shock absorber increases. For example, in the case of changing the stroke position of the main piston rod that increases the damping force, the secondary rod needs to be changed, which also leads to an increase in cost.

[0154] The shock absorber 1 of the first embodiment includes: a tube 3, the interior of which forms an inner chamber 6; a piston rod 21 having an axial first end 22 disposed within the tube 3 and an axial second end 23 disposed outside the tube 3; a piston assembly 17 coupled to an axially intermediate position of the piston rod 21, dividing the inner chamber 6 into a first chamber 19 on the second end 23 side of the piston rod 21 and a second chamber 20 on the first end 22 side, generating a damping force when the piston rod 21 moves; and a damping force increasing mechanism 221 that increases the damping force when the piston assembly 17 moves toward the second chamber 20. Furthermore, the damping force increasing mechanism 221 of the shock absorber 1 includes: a first cylinder 101 coupled to a position of the piston rod 21 closer to the first end 22 than the piston assembly 17; and a dividing piston 143 that, when the piston assembly 17 moves toward the second chamber 20, enters the first cylinder 101 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0155] Thus, in shock absorber 1, first cylinder 101, which forms first cylinder inner chamber 214 by allowing partitioning piston 143 to enter when piston assembly 17 moves toward second chamber 20, is connected to piston rod 21 at a position closer to first end 22 than piston assembly 17. Consequently, shock absorber 1 can simplify its structure, thereby minimizing cost increases. For example, to change the stroke position of piston rod 21 that increases damping force, simply changing the position of partitioning piston 143 is sufficient, thus minimizing cost increases.

[0156] The shock absorber 1 has the second cylinder 142 supporting the divided piston 143 provided in the valve body assembly 31 provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the divided piston 143 can be supported with a simple structure.

[0157] Shock absorber 1 supports divided piston 143 by second cylinder 142 having a smaller diameter than first cylinder 101, thereby stably supporting divided piston 143. Furthermore, shaft 126 of bolt 124 of valve body assembly 31 can be extended toward piston assembly 17 to support divided piston 143.

[0158] The shock absorber 1 is provided with a communication passage 208 between the partition piston 143 and the second cylinder 142, through which the air in the second cylinder 142 can flow. Therefore, when the oil L is filled into the tube 3, the shock absorber 1 can smoothly discharge the air in the second cylinder 142 to the outside.

[0159] The shock absorber 1 has the first cylinder 101 of the damping force increasing mechanism 221 connected to the relief valve assembly 62 connected to the piston rod 21 closer to the first end 22 than the piston assembly 17. Therefore, the shock absorber 1 can simplify its structure and suppress cost increases.

[0160] The relief valve assembly 62 of the shock absorber 1 includes a support piston 81 connected to a portion of the piston rod 21 closer to the first end 22 than the piston assembly 17, thereby supporting the first cylinder 101; and a plate-shaped relief valve 82 provided on the support piston 81. Therefore, even when the shock absorber 1 includes the relief valve 82 in the damping force increasing mechanism 221, the structure can be simplified, thereby suppressing cost increases.

[0161] Shock absorber 1 is provided with a passage 210 in partitioning piston 143, connecting the outer chamber 215 of second chamber 20 with the inner chamber 214 of first cylinder. A movable ring 173 opens passage 210 when piston assembly 17 moves toward first chamber 19 and closes passage 210 when piston assembly 17 moves toward second chamber 20. Therefore, even when damping force is increased by damping force increasing mechanism 221 during the contraction stroke, damping force by damping force increasing mechanism 221 can be smoothly reduced during the extension stroke.

[0162] [Second embodiment]

[0163] Next, mainly based on Figure 5 and Figure 6 The shock absorber of the second embodiment will be described focusing on the parts that are different from the first embodiment. It should be noted that the parts common to the first embodiment are denoted by the same names and reference numerals.

[0164] The shock absorber 1A includes a damping force increasing mechanism 221A that is partially different from the damping force increasing mechanism 221, instead of the damping force increasing mechanism 221. The damping force increasing mechanism 221A includes a divided piston 143A that is partially different from the divided piston 143, instead of the divided piston 143. The divided piston 143A is similar to the divided piston 143 of the first embodiment and is attached to the end of the second cylinder 142 on the opposite side from the base adapter 141 in the axial direction, that is, the upper end of the second cylinder 142.

[0165] The dividing piston 143A includes a base member 171A that is partially different from the base member 171, instead of the base member 171. The base member 171A includes a main body portion 181A, a connecting portion 182A, and a cylindrical portion 183A.

[0166] The main body 181A is cylindrical. A recess 301 is formed on one axial side of the main body 181A and is recessed toward the other axial side. The recess 301 is provided at the radial center of the main body 181A.

[0167] The connecting portion 182A extends radially outward from one axial end of the main body 181A. The connecting portion 182A is annular and extends around the entire circumference of the main body 181A. The outer diameter of the connecting portion 182A is smaller than the inner diameter of the main body 111 of the first cylinder 101.

[0168] The main body 181A has an axial groove 191 formed on its outer periphery, excluding the connecting portion 182A, extending in the axial direction of the main body 181A. A radial groove 192, similar to that of the first embodiment, is formed in the connecting portion 182A, extending through the connecting portion 182A in the radial direction thereof, on the axial side of the axial groove 191.

[0169] The cylindrical portion 183A extends from the outer peripheral side of the connecting portion 182A toward the opposite side of the connecting portion 182A from the main body portion 181A in the axial direction of the connecting portion 182A.

[0170] In the axial direction of the base member 171A, the recessed portion 301 of the main body portion 181A is formed from the end surface of the main body portion 181A on the cylindrical portion 183A side to a position on the opposite side of the connecting portion 182A from the cylindrical portion 183A.

[0171] The dividing piston 143A includes a locking member 172A that is partially different from the locking member 172 in place of the locking member 172 .

[0172] The locking member 172A includes a contact portion 305 , a fitting portion 201A, and a flange portion 202A.

[0173] The fitting portion 201A has a cylindrical shape.

[0174] The flange portion 202A extends from one axial end of the fitting portion 201A toward the radially outer side of the fitting portion 201A. The flange portion 202A is disk-shaped. The outer diameter of the flange portion 202A is smaller than the inner diameter of the main body portion 111 of the first cylinder 101.

[0175] The contact portion 305 extends radially inward from the end of the fitting portion 201A opposite the flange portion 202A in the axial direction. The contact portion 305 is annular and has an inner diameter equal to the inner diameter of the opening of the recess 301.

[0176] like Figure 6 As shown, a passage groove 205A is formed in the locking member 172A, continuously extending from the flange portion 202A and the portion of the fitting portion 201A on the flange portion 202A side in the axial direction. The passage groove 205A penetrates the flange portion 202A in both the axial direction and the radial direction of the flange portion 202A. The passage groove 205A also penetrates the fitting portion 201A in the radial direction. The locking member 172A is formed with a plurality of passage grooves 205A spaced apart in the circumferential direction.

[0177] The movable ring 173 is partially broken in the circumferential direction to have a circumferential gap 307, thereby being able to expand and contract in the circumferential direction and radial direction. The inner diameter of the movable ring 173 in its natural state is smaller than the outer diameter of the cylindrical portion 183A of the base member 171A and the outer diameter of the flange portion 202A of the locking member 172A. The movable ring 173 is reduced in diameter, as shown in FIG. Figure 5 As shown, the outer diameter is equal to the inner diameter of the main body 111 of the first cylinder 101. In this state, the inner diameter of the movable ring 173 is larger than the outer diameter of the fitting portion 201A of the locking member 172A. In addition, in this state, the circumferential gap 307 of the movable ring 173 is not zero.

[0178] The base member 171A of the partitioned piston 143A is fixed to the second cylinder 142 by fitting the main body portion 181A with the inner circumference of the upper end portion of the second cylinder 142. At this point, the connecting portion 182A of the base member 171A abuts the second cylinder 142 in the axial direction of the base member 171A. The base member 171A thus fixed to the second cylinder 142 is similar to the first embodiment, and the axial groove 191 and the radial groove 192 form a communication path 208 that connects the radially inner side and the radially outer side of the second cylinder 142.

[0179] The movable ring 173 is placed on the upper side of the cylindrical portion 183A of the base member 171A in a state where the partition piston 143A is fixed to the second cylinder 142 in this manner.

[0180] From this position, the dividing piston 143A is inserted into the fitting portion 201A radially inward of the movable ring 173. The locking member 172A is then pressed into the inner circumference of the cylindrical portion 183A of the base member 171A, securing it to the base member 171A. At this point, the abutment portion 305 of the locking member 172A abuts the end surface of the main body 181A of the base member 171A on the axial side of the cylindrical portion 183A. Consequently, the flange 202A of the locking member 172A covers the movable ring 173 on the side opposite the cylindrical portion 183A in the axial direction. As a result, the movable ring 173 is axially clamped between the cylindrical portion 183A of the base member 171A and the flange 202A of the locking member 172A.

[0181] The length of movable ring 173 in the axial direction of partition piston 143A is shorter than the distance between cylindrical portion 183A and flange portion 202A. Therefore, movable ring 173 is movable in the axial direction between cylindrical portion 183A and flange portion 202A.

[0182] When the movable ring 173 moves axially away from the cylindrical portion 183A, it opens a passage 210A formed by the passages within the plurality of passage grooves 205A of the locking member 172A and the passage between the movable ring 173 and the cylindrical portion 183A of the base member 171A. When the movable ring 173 abuts the cylindrical portion 183A in the axial direction, it closes the passage 210A.

[0183] Since the locking member 172A is cylindrical, the partition piston 143A has a recessed portion 308 formed at its radial center. The recessed portion 308 is recessed toward the second cylinder 142 along the axial direction of the partition piston 143A from the end surface of the partition piston 143A on the opposite side from the second cylinder 142. The recessed portion 308 includes a recessed portion 301.

[0184] Dividing piston 143A is supported by bottom member 12 of pipe 3 via second cylinder 142, base adapter 141, and seat member 32 of valve body assembly 31. In other words, second cylinder 142, which has a smaller diameter than first cylinder 101, is provided in valve body assembly 31 via base adapter 141 and supports dividing piston 143A. Dividing piston 143A and dividing piston support member 211 are provided in second chamber 20.

[0185] In the shock absorber 1A, the inside of the second cylinder 142 forms a second cylinder inner chamber 213. The second cylinder inner chamber 213 is surrounded by the valve body assembly 31, the base adapter 141, the second cylinder 142, and the partitioning piston 143A.

[0186] The dividing piston 143A enters the first cylinder 101 from below through the lower end opening of the first cylinder 101 and retracts downward.

[0187] Here, when piston rod 21 is in the first predetermined range where cup 100 including first cylinder 101 is positioned above partition piston 143A and cup 100 and partition piston 143A are not fitted together, the entire interior of cup 100 becomes second chamber 20 .

[0188] From this position, during the retraction stroke, the piston rod 21 moves to a second predetermined range, closer to the base adapter 141 than the first predetermined range. Consequently, the cup 100, which moves integrally with the piston rod 21, causes the movable ring 173 of the partitioning piston 143A to enter the expanded diameter portion 112 of the first cylinder 101, covering the partitioning piston 143A. The movable ring 173 then fits into the main body 111 of the first cylinder 101. Initially, the movable ring 173 is pressed against the cylindrical portion 183A of the base member 171A by friction with the contacting first cylinder 101, blocking the passage 210A. During the subsequent retraction stroke, while pressed against the cylindrical portion 183A and blocking the passage 210A, the movable ring 173 slides within the first cylinder 101, approaching the support piston 81.

[0189] When the first cylinder 101 is engaged with the movable ring 173 of the partitioning piston 143A, the second chamber 20 is divided into a first cylinder inner chamber 214 within the first cylinder 101 and a cylinder outer chamber 215 outside the first cylinder 101. The first cylinder inner chamber 214 is the portion between the relief valve assembly 62 and the partitioning piston 143A within the first cylinder 101. The cylinder outer chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. The passage 210A of the partitioning piston 143A connects the cylinder outer chamber 215 with the first cylinder inner chamber 214, and the movable ring 173 can open and close this passage 210A.

[0190] During the retraction stroke within the second predetermined range, as described above, the cup 100 and the piston rod 21 move toward the base adapter 141, with the movable ring 173 abutting the cylindrical portion 183A and blocking the passage 210A. In the upper portion of the second predetermined range, similar to the upper portion of the second predetermined range in the first embodiment, the movable ring 173 is positioned within the plurality of grooves 116 provided in the first cylinder 101, allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the passages within the grooves 116. At this point, as the cup 100 approaches the base adapter 141, the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 decreases, ultimately reaching zero. Consequently, the damping force generated by the cup 100 and the partitioning piston 143B, including the first cylinder 101, gradually increases. The movable ring 173 engages with the main body 111 of the first cylinder 101 at a position where the number of grooves 116, which allow the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215, reaches zero, thereby fully blocking the passage 210A. During the subsequent contraction stroke, the movable ring 173 slides within the first cylinder 101, approaching the support piston 81 while fully blocking the passage 210A. In other words, the movable ring 173 blocks the passage 210A when the piston assembly 17 moves toward the second chamber 20.

[0191] The relief valve assembly 62, the first cylinder 101 connected to the relief valve assembly 62, and the partitioning piston 143A constitute a damping force increasing mechanism 221A that increases the damping force in addition to the damping force generated by the piston assembly 17 when the piston assembly 17 moves toward the second chamber 20. The damping force increasing mechanism 221A includes the partitioning piston 143A, which, when the piston assembly 17 moves toward the second chamber 20, moves into the first cylinder 101 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0192] Furthermore, during the contraction stroke within the second predetermined range, as described above, with the partitioning piston 143A blocking the passage 210A, the cup 100 moves toward the base adapter 141. At this time, the relief valve 82 opens, similar to the first embodiment, based on the movement speed of the piston rod 21, piston 18, and support piston 81 relative to the tube 3, i.e., the piston speed.

[0193] During the extension stroke within the second predetermined range, the cup 100 moves together with the piston rod 21 away from the base adapter 141. Consequently, the movable ring 173, which divides the piston 143A, moves axially away from the cylindrical portion 183A due to friction with the first cylinder 101, opening the passage 210A. During the subsequent extension stroke, the cup 100 moves away from the base adapter 141 while maintaining the movable ring 173 opening the passage 210A. As the cup 100 moves away from the base adapter 141, oil L flows from the portion of the cylinder outer chamber 215 between the first cylinder 101 and the second cylinder 142 into the first cylinder inner chamber 214 via passage 210A. This reduces the damping force on the extension movement of the piston rod 21.

[0194] During the extension stroke, starting from the state where movable ring 173 is positioned closer to the support piston 81 than all grooves 116 in first cylinder 101, when cup 100 separates the support piston 81 from movable ring 173 by a predetermined distance, movable ring 173 is positioned within groove 116 provided in first cylinder 101, opening groove 116 into first cylinder inner chamber 214. Consequently, in addition to flowing through passage 210A, oil L also flows from cylinder outer chamber 215 into first cylinder inner chamber 214 through the passage within groove 116, reducing the damping force exerted on the extension direction of piston rod 21. At this time, multiple grooves 116 gradually reduce the damping force exerted on the extension direction of piston rod 21.

[0195] Next, main operations of the shock absorber 1A that differ from those of the shock absorber 1 will be described.

[0196] "The piston rod 21 is in the retraction stroke of the second predetermined range"

[0197] During this contraction stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Furthermore, the cup 100 of the damping force increasing mechanism 221A moves in the axial direction of the tube 3 toward the base adapter 141, causing the movable ring 173 of the partitioning piston 143A to fit within the first cylinder 101. Initially, the movable ring 173 is pressed against the cylindrical portion 183A of the base member 171A, thereby blocking the passage 210A.

[0198] In this state, the cup 100 moves toward the base adapter 141. Consequently, the oil L in the first cylinder inner chamber 214 is throttled by the multiple grooves 116 provided in the first cylinder 101 and flows toward the outer cylinder chamber 215. Consequently, the damping force generated by the damping force increasing mechanism 221A increases. At this point, as the cup 100 approaches the base adapter 141, the number of grooves 116 that allow the oil L to flow from the first cylinder inner chamber 214 to the outer cylinder chamber 215 decreases, ultimately reaching zero. Consequently, the damping force generated by the damping force increasing mechanism 221A gradually increases, and the damping force relative to the retraction direction of the piston rod 21 gradually increases. Thus, the amount of damping force generated by the damping force increasing mechanism 221A increases in addition to the damping force generated by the piston assembly 17. Here, at the position where the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 is zero, the movable ring 173 engages with the main body 111 of the first cylinder 101, fully blocking the passage 210A. Therefore, during the contraction stroke after the movable ring 173 has reduced the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 to zero, the oil L flowing from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the space between the first cylinder 101 and the partition piston 143A is throttled to the maximum extent. Consequently, the damping force is further increased.

[0199] Here, when the cup 100 moves toward the base adapter 141, the relief valve 82 of the relief valve assembly 62 opens according to the piston speed. As a result, the oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages within the plurality of passage holes 85. This suppresses an excessive increase in the pressure in the first cylinder inner chamber 214.

[0200] "The piston rod 21 is within the second predetermined range of extension stroke"

[0201] During this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Furthermore, the cup 100 of the damping force increasing mechanism 221A moves in the axial direction of the tube 3 away from the base adapter 141. Initially, the movable ring 173 opens the passage 210A.

[0202] With passage 210A thus open, cup 100 moves away from base adapter 141. Consequently, oil L in outer cylinder chamber 215 flows from between first cylinder 101 and second cylinder 142 to first cylinder inner chamber 214 via passage 210A. When movable ring 173 is positioned on the opposite side of base adapter 141 relative to all grooves 116 provided in first cylinder 101, oil L flows from outer cylinder chamber 215 to first cylinder inner chamber 214 via passages within grooves 116, in addition to flow through passage 210A. At this point, the further cup 100 moves away from base adapter 141, the greater the number of grooves 116 that allow oil L to flow from outer cylinder chamber 215 to first cylinder inner chamber 214. This gradually reduces the damping force against the extension movement of piston rod 21.

[0203] The shock absorber 1A of the second embodiment includes a damping force increasing mechanism 221A that increases the damping force when the piston assembly 17 moves toward the second chamber 20. The damping force increasing mechanism 221A of the shock absorber 1 includes a first cylinder 101 coupled to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17; and a split piston 143A that, when the piston assembly 17 moves toward the second chamber 20, enters the first cylinder 101 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0204] Thus, in the shock absorber 1A, the first cylinder 101, which forms the first cylinder inner chamber 214 by causing the partitioning piston 143A to enter when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17. Consequently, the shock absorber 1A can simplify its structure and suppress cost increases. For example, to change the stroke position of the piston rod 21 that increases the damping force, it is sufficient to simply change the position of the partitioning piston 143A, thus suppressing cost increases.

[0205] In the shock absorber 1A, the second cylinder 142 supporting the divided piston 143A is provided in the valve body assembly 31 provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the divided piston 143A can be supported with a simple structure.

[0206] Shock absorber 1A supports divided piston 143A by second cylinder 142 having a smaller diameter than first cylinder 101, thereby stably supporting divided piston 143A. Furthermore, shaft 126 of bolt 124 of valve body assembly 31 can be extended toward piston assembly 17 to support divided piston 143A.

[0207] The shock absorber 1A has a communication passage 208 between the partition piston 143A and the second cylinder 142, through which air in the second cylinder 142 can flow. Therefore, when the oil L is filled into the tube 3, the shock absorber 1A can smoothly discharge the air in the second cylinder 142 to the outside.

[0208] Shock absorber 1A is provided with a passage 210A in partitioned piston 143A, connecting the outer chamber 215 of second chamber 20 with the inner chamber 214 of first cylinder. A movable ring 173 opens passage 210A when piston assembly 17 moves toward first chamber 19 and blocks passage 210A when piston assembly 17 moves toward second chamber 20. Therefore, even when damping force is increased by damping force increasing mechanism 221A during the contraction stroke, damping force by damping force increasing mechanism 221A can be smoothly reduced during the extension stroke.

[0209] In the shock absorber 1A of the second embodiment, the divided piston 143A has a recessed portion 308 at its radial center that is recessed along its axial direction toward the second cylinder 142. Therefore, the shock absorber 1A can reduce the weight of the divided piston 143A.

[0210] [Third embodiment]

[0211] Next, mainly based on Figure 7 and Figure 8 The shock absorber of the third embodiment will be described focusing on the parts that are different from the first embodiment. It should be noted that the parts common to the first embodiment are denoted by the same names and reference numerals.

[0212] In the shock absorber 1B of the third embodiment, instead of the divided piston support body 211, the base member 171, and the locking member 172 of the base adapter 141 and the second cylinder 142 of the first embodiment, these are integrated. Figure 7 and Figure 8 The movable ring support body 211B shown is formed integrally by, for example, injection molding of a synthetic resin material.

[0213] like Figure 8 As shown, the movable ring support body 211B includes a support base portion 141B, a support cylindrical portion 142B, a ring support portion 310 , and a reinforcement portion 311 .

[0214] The support base portion 141B is annular. A communication hole 162B is formed in the support base portion 141B, penetrating the support base portion 141B in the axial direction. A plurality of communication holes 162B are provided in the support base portion 141B at equal intervals in the circumferential direction of the support base portion 141B.

[0215] The support cylindrical portion 142B extends from the inner peripheral side of the support base portion 141B to one side along the axial direction of the support base portion 141B. The support cylindrical portion 142B is cylindrical. The plurality of communication holes 162B of the support base portion 141B are arranged at a position radially outside the support cylindrical portion 142B. Figure 7 As shown, the outer diameter of the support cylindrical portion 142B is smaller than the inner diameter of the main body portion 111 of the first cylinder 101. A communication passage 208B is formed at the end of the support cylindrical portion 142B on the axial side opposite to the support base portion 141B. The communication passage 208B penetrates the support cylindrical portion 142B in the radial direction of the support cylindrical portion 142B.

[0216] The ring support portion 310 is provided at the end portion of the support cylindrical portion 142B on the opposite side from the support base portion 141B in the axial direction. The ring support portion 310 includes a base portion 171B and a locking portion 172B.

[0217] The base portion 171B is provided at the end portion of the support cylindrical portion 142B on the axial side opposite to the support base portion 141B. The base portion 171B is in the shape of a circular plate. The outer diameter of the base portion 171B is equal to the outer diameter of the support cylindrical portion 142B. The base portion 171B closes the end portion of the support cylindrical portion 142B on the axial side opposite to the support base portion 141B. A recess 313 is formed in the radial center of the base portion 171B, which is recessed from the end surface on the axial side opposite to the support cylindrical portion 142B toward the support cylindrical portion 142B.

[0218] Movable ring support body 211B is formed with support base 141B, support cylindrical portion 142B, and base portion 171B to form a recessed portion 315 that extends from the end surface of support base 141B on the axial side opposite support cylindrical portion 142B to base portion 171B. Communication path 208B formed in support cylindrical portion 142B opens near the bottom of recessed portion 315.

[0219] A reinforcement portion 311 is formed in the recessed portion 315 of the movable ring support body 211B. The reinforcement portion 311 is in the shape of a triangular plate. The reinforcement portion 311 connects a portion of the support cylindrical portion 142B on the side of the base portion 171B in the axial direction to a portion of the support cylindrical portion 142B on the side of the base portion 171B in the axial direction. A plurality of reinforcement portions 311 are formed on the movable ring support body 211B at intervals in the circumferential direction thereof. The connecting path 208B is arranged in a phase different from that of these reinforcement portions 311 in the circumferential direction of the movable ring support body 211B.

[0220] The locking portion 172B is provided at a position on the opposite side of the base portion 171B from the supporting cylindrical portion 142B in the axial direction. The locking portion 172B includes a cylindrical portion 183B and a flange portion 202B.

[0221] The cylindrical portion 183B extends from the end surface of the base portion 171B on the opposite side from the support cylindrical portion 142B in the axial direction in the direction opposite to the support cylindrical portion 142B. The cylindrical portion 183B is cylindrical and coaxial with the base portion 171B. The outer diameter of the cylindrical portion 183B is smaller than the outer diameter of the base portion 171B.

[0222] The flange portion 202B extends radially outward from the end of the cylindrical portion 183B on the opposite side from the base portion 171B in the axial direction. The outer diameter of the flange portion 202B is smaller than the inner diameter of the main body portion 111 of the first cylinder 101 .

[0223] A passage groove 205B is formed in the retaining portion 172B, continuously with the flange portion 202B and the cylindrical portion 183B. The passage groove 205B penetrates the flange portion 202B in the axial direction and radial direction of the flange portion 202B. The passage groove 205B penetrates the fitting portion 201B in the radial direction of the fitting portion 201B. The retaining portion 172B is provided with a plurality of passage grooves 205B spaced apart in the circumferential direction. This allows the retaining portion 172B to be elastically deformed so that the base portion 171B side in the axial direction serves as the base end, with the side opposite the base portion 171B becoming smaller in diameter overall.

[0224] The support base portion 141B of the movable ring support 211B is press-fitted and fixed to the inner circumference of the pipe 3. At this point, the lower end of the support base portion 141B abuts the upper surface of the outer circumference of the base portion 131 of the seat member 32. Furthermore, the recessed portion 315 of the movable ring support 211B prevents contact with the bolts 124 and nuts 125 of the valve body assembly 31. Furthermore, the support base portion 141B of the movable ring support 211B radially surrounds the disk valve 123 of the valve body assembly 31. In other words, the support base portion 141B is positioned radially outward from the disk valve 123. The movable ring support 211B is supported by the valve body assembly 31 in the axial direction and by the pipe 3 in the radial direction.

[0225] The supporting cylindrical portion 142B of the movable ring support 211B extends from the supporting base portion 141B to the side of the supporting base portion 141B axially opposite to the valve body assembly 31. The ring supporting portion 310 of the movable ring support 211B is provided at the end portion of the supporting cylindrical portion 142B axially opposite to the valve body assembly 31. The movable ring support 211B is provided in the second chamber 20.

[0226] As described above, the support base portion 141B is provided at one axial end of the movable ring support body 211B and is placed on the valve body assembly 31. The inner peripheral portion of the support base portion 141B increases in diameter toward the valve body assembly 31 in the axial direction of the support base portion 141B.

[0227] The inner diameter of the movable ring 173 in its natural state is smaller than the outer diameter of the base portion 171B and the outer diameter of the flange portion 202B of the locking portion 172B. The movable ring 173 is reduced in diameter, and its outer diameter is equal to the inner diameter of the main body 111 of the first cylinder 101. In this state, the inner diameter of the movable ring 173 is larger than the outer diameter of the cylindrical portion 183B of the locking portion 172B. Furthermore, in this state, the circumferential gap 307 of the movable ring 173 is not zero.

[0228] The movable ring 173 is assembled to the locking portion 172B from the side of the locking portion 172B opposite the base portion 171B in the axial direction. At this time, the movable ring 173 is assembled to the locking portion 172B while elastically deforming the locking portion 172B so that the side of the locking portion 172B opposite the base portion 171B in the axial direction has a smaller diameter. Once the movable ring 173 is assembled, the locking portion 172B recovers from the elastic deformation. In this state, the flange 202B of the locking portion 172B covers the movable ring 173 on the side of the movable ring 173 opposite the base portion 171B in the axial direction. Thus, the movable ring 173 is clamped in the axial direction by the base portion 171B and the flange 202B of the locking portion 172B.

[0229] The ring support portion 310 of the movable ring support body 211B and the movable ring 173 attached to the ring support portion 310 constitute the partition piston 143B. In the axial direction of the partition piston 143B, the length of the movable ring 173 is shorter than the distance between the base portion 171B and the flange portion 202B. Therefore, the movable ring 173 can move axially between the base portion 171B and the flange portion 202B.

[0230] As described above, the movable ring 173 is axially movable between the base portion 171B and the flange portion 202B. When the movable ring 173 moves axially away from the base portion 171B, it opens the passage 210B formed by the passages within the plurality of passage grooves 205B of the locking portion 172B, the passage between the movable ring 173 and the cylindrical portion 183B of the locking portion 172B, and the passage between the movable ring 173 and the base portion 171B. When the movable ring 173 abuts the base portion 171B in the axial direction, it closes the passage 210B.

[0231] The partitioning piston 143B is supported by the bottom member 12 of the pipe 3 via the support cylindrical portion 142B, the support base portion 141B, and the seat member 32 of the valve body assembly 31. In other words, the support cylindrical portion 142B, which has a smaller diameter than the first cylinder 101, is provided in the valve body assembly 31 via the support base portion 141B to support the partitioning piston 143B.

[0232] The area surrounded by the valve body assembly 31, the support base 141B, the support cylindrical portion 142B, and the base portion 171B of the ring support 310 forms the second cylinder chamber 213. The second cylinder chamber 213 communicates with the portion of the second chamber 20 between the tube 3 and the first cylinder 101, and the portion of the second chamber 20 between the tube 3 and the support cylindrical portion 142B, via a passage within the communication hole 162B of the support base 141B. The second cylinder chamber 213 constitutes a portion of the second chamber 20. In other words, the support base 141B is provided with a communication hole 162B that forms the second cylinder chamber 213, which forms part of the second chamber 20, within the support cylindrical portion 142B. The communication passage 208B of the support cylindrical portion 142B connects the second cylinder chamber 213 within the support cylindrical portion 142B with the outside of the support cylindrical portion 142B. When air exists in the second cylinder chamber 213 in the movable ring support 211B, the communication path 208B can allow the air to flow out of the movable ring support 211B.

[0233] The dividing piston 143B enters the first cylinder 101 from below through the lower end opening of the first cylinder 101 and retracts downward.

[0234] Here, when piston rod 21 is in the first predetermined range where cup 100 including first cylinder 101 is positioned above partition piston 143B and cup 100 and partition piston 143B are not fitted together, the entire interior of cup 100 becomes second chamber 20 .

[0235] From this position, during the retraction stroke, the piston rod 21 moves to a second predetermined range, closer to the support base 141B than the first predetermined range. Consequently, the cup 100, which moves integrally with the piston rod 21, causes the movable ring 173 of the partitioning piston 143B to enter the expanded diameter portion 112 of the first cylinder 101, covering the partitioning piston 143B. The movable ring 173 then fits into the main body 111 of the first cylinder 101. Initially, the movable ring 173 is pressed against the base 171B of the movable ring support 211B by friction with the first cylinder 101, thereby blocking the passage 210B. During the subsequent retraction stroke, while pressed against the base 171B and blocking the passage 210B, the movable ring 173 slides within the first cylinder 101, approaching the support piston 81.

[0236] When the first cylinder 101 is engaged with the movable ring 173 of the partitioning piston 143B, the second chamber 20 is divided into a first cylinder inner chamber 214 within the first cylinder 101 and a cylinder outer chamber 215 outside the first cylinder 101. The first cylinder inner chamber 214 is the portion between the relief valve assembly 62 and the partitioning piston 143B within the first cylinder 101. The cylinder outer chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. The passage 210B of the partitioning piston 143B connects the cylinder outer chamber 215 with the first cylinder inner chamber 214, and the movable ring 173 can open and close this passage 210B.

[0237] During the retraction stroke within the second predetermined range, as described above, the cup 100 and piston rod 21 move toward the support base 141B, with the movable ring 173 in contact with the base 171B, blocking the passage 210B. In the upper portion of the second predetermined range, similar to the upper portion of the second predetermined range in the first embodiment, the movable ring 173 is positioned within the plurality of grooves 116 provided in the first cylinder 101, allowing the oil L to flow from the first cylinder inner chamber 214 to the outer cylinder chamber 215 via the passages within the plurality of grooves 116. At this point, as the cup 100 approaches the support base 141B, the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the outer cylinder chamber 215 decreases, ultimately reaching zero. Consequently, the damping force generated by the cup 100 and the partitioned piston 143B, including the first cylinder 101, gradually increases. The movable ring 173 engages with the main body 111 of the first cylinder 101 at a position where the number of grooves 116, which allow the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215, reaches zero, thereby fully blocking the passage 210B. During the subsequent contraction stroke, the movable ring 173 slides within the first cylinder 101, approaching the support piston 81 while fully blocking the passage 210B. In other words, the movable ring 173 blocks the passage 210B when the piston assembly 17 moves toward the second chamber 20.

[0238] The relief valve assembly 62, the first cylinder 101 connected to the relief valve assembly 62, and the partitioning piston 143B constitute a damping force increasing mechanism 221B that increases the damping force in addition to the damping force generated by the piston assembly 17 when the piston assembly 17 moves toward the second chamber 20. The damping force increasing mechanism 221B includes the partitioning piston 143B, which, when the piston assembly 17 moves toward the second chamber 20, enters the interior of the first cylinder 101 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0239] Furthermore, during the contraction stroke within the second predetermined range, as described above, with partition piston 143B blocking passage 210B, cup 100 moves toward support base 141B. At this time, relief valve 82 opens based on the movement speed of piston rod 21, piston 18, and support piston 81 relative to tube 3, i.e., the piston velocity.

[0240] During the extension stroke within the second predetermined range, the cup 100 moves together with the piston rod 21 away from the support base 141B. Consequently, the movable ring 173, which divides the piston 143B, separates axially from the base 171B due to friction with the first cylinder 101, opening the passage 210B. During the subsequent extension stroke, the cup 100 moves away from the support base 141B, maintaining the movable ring 173's position to open the passage 210B. As the cup 100 moves away from the support base 141B, oil L flows from the portion of the outer chamber 215 between the first cylinder 101 and the support tubular portion 142B via passage 210B into the first cylinder inner chamber 214. This reduces the force attenuating the piston rod 21's movement in the extension direction.

[0241] During the extension stroke, starting from the state where movable ring 173 is positioned closer to the support piston 81 than all grooves 116 in first cylinder 101, when cup 100 separates the support piston 81 from movable ring 173 by a predetermined distance, movable ring 173 is positioned within groove 116 provided in first cylinder 101, opening groove 116 into first cylinder inner chamber 214. Consequently, in addition to flowing through passage 210B, oil L also flows from cylinder outer chamber 215 into first cylinder inner chamber 214 through the passage within groove 116, reducing the damping force exerted on the extension direction of piston rod 21. At this time, multiple grooves 116 gradually reduce the damping force exerted on the extension direction of piston rod 21.

[0242] Next, main operations of the shock absorber 1B that differ from those of the shock absorber 1 will be described.

[0243] "The piston rod 21 is in the retraction stroke of the second predetermined range"

[0244] During this contraction stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Furthermore, the cup 100 of the damping force increasing mechanism 221B moves in the axial direction of the tube 3 toward the support base 141B, causing the movable ring 173 of the partitioning piston 143B to fit within the first cylinder 101. Initially, the movable ring 173 is pressed against the base 171B, blocking the passage 210B.

[0245] In this state, the cup-shaped member 100 moves in a direction approaching the support base portion 141B. As a result, the oil L in the first cylinder inner chamber 214 is throttled by the multiple grooves 116 provided in the first cylinder 101 and flows toward the cylinder outer chamber 215. Therefore, the damping force generated by the damping force increasing mechanism 221B increases. At this time, the closer the cup-shaped member 100 is to the support base portion 141B, the smaller the number of grooves 116 among the multiple grooves 116 that allow the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215, and eventually reaches zero. As a result, the damping force generated by the damping force increasing mechanism 221B gradually increases, and the damping force relative to the movement in the contraction direction of the piston rod 21 gradually increases. In this way, the amount of damping force generated by the damping force increasing mechanism 221B increases in addition to the damping force generated by the piston assembly 17. Here, at the position where the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 is zero, the movable ring 173 engages with the main body 111 of the first cylinder 101, fully blocking the passage 210B. Therefore, during the contraction stroke after the movable ring 173 has reduced the number of grooves 116 allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 to zero, the oil L flowing from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the space between the first cylinder 101 and the partition piston 143B is throttled to the maximum extent. Consequently, the damping force is further increased.

[0246] Here, when cup 100 moves toward support base 141B, relief valve 82 of relief valve assembly 62 opens according to piston speed. Oil L then flows from first cylinder inner chamber 214 to outer chamber 215 via the passages within multiple passage holes 85. This prevents excessive pressure increases in first cylinder inner chamber 214.

[0247] "The piston rod 21 is within the second predetermined range of extension stroke"

[0248] During this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Furthermore, the cup 100 of the damping force increasing mechanism 221B moves away from the support base 141B in the axial direction of the tube 3. Initially, the movable ring 173 opens the passage 210B.

[0249] With passage 210B thus open, cup 100 moves away from support base 141B. Consequently, oil L in outer chamber 215 flows from between first cylinder 101 and support cylindrical portion 142B into first cylinder inner chamber 214 via passage 210B. When movable ring 173 is positioned on the opposite side of support base 141B relative to all grooves 116 provided in first cylinder 101, the position of grooves 116 in first cylinder 101 allows oil L to flow from outer chamber 215 into first cylinder inner chamber 214 via passages within grooves 116, in addition to flow through passage 210B. At this point, the further cup 100 moves away from support base 141B, the greater the number of grooves 116 that allow oil L to flow from outer chamber 215 into first cylinder inner chamber 214. This gradually reduces the damping force on the extension movement of piston rod 21.

[0250] The shock absorber 1B of the third embodiment includes a damping force increasing mechanism 221B that increases the damping force when the piston assembly 17 moves toward the second chamber 20. The damping force increasing mechanism 221B of the shock absorber 1B includes a first cylinder 101 coupled to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17; and a partitioning piston 143B that, when the piston assembly 17 moves toward the second chamber 20, enters the first cylinder 101 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0251] Thus, in shock absorber 1B, first cylinder 101, which forms first cylinder inner chamber 214 by allowing partitioning piston 143B to enter when piston assembly 17 moves toward second chamber 20, is connected to piston rod 21 at a position closer to first end 22 than piston assembly 17. Consequently, shock absorber 1B can simplify its structure and minimize cost increases. For example, to change the stroke position of piston rod 21 that increases damping force, simply change the position of partitioning piston 143B, thus minimizing cost increases.

[0252] The shock absorber 1B has a movable ring support body 211B that supports the movable ring 173 provided in the valve body assembly 31 provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the divided piston 143B can be supported with a simple structure.

[0253] The shock absorber 1B supports the divided piston 143B by the support cylindrical portion 142B having a smaller diameter than that of the first cylinder 101 , and thus can stably support the divided piston 143B.

[0254] The shock absorber 1B has a communication passage 208B in the support cylindrical portion 142B that allows air to flow through the support cylindrical portion 142B. Therefore, when the oil L is filled into the tube 3 , the shock absorber 1B can smoothly discharge the air in the support cylindrical portion 142B to the outside of the movable ring support body 211B.

[0255] Shock absorber 1B is provided with a passage 210B in partitioning piston 143B, connecting the outer chamber 215 of second chamber 20 with the inner chamber 214 of first cylinder. A movable ring 173 opens passage 210B when piston assembly 17 moves toward first chamber 19 and closes passage 210B when piston assembly 17 moves toward second chamber 20. This allows shock absorber 1B to smoothly reduce the damping force of damping force increasing mechanism 221B during the extension stroke, even when damping force is increased by damping force increasing mechanism 221B during the contraction stroke.

[0256] In the damper 1B, the movable ring support body 211B supporting the movable ring 173 is integrally formed by injection molding of a synthetic resin material. Therefore, the damper 1B can achieve cost reduction.

[0257] [Fourth embodiment]

[0258] Next, mainly based on Figure 9 and Figure 10 The shock absorber of the fourth embodiment will be described focusing on the parts that are different from the second embodiment. Note that the parts common to the second embodiment are denoted by the same names and reference numerals.

[0259] The shock absorber 1C of the fourth embodiment includes a damping force increasing mechanism 221C, which partially differs from the damping force increasing mechanism 221A, in place of the damping force increasing mechanism 221A. The damping force increasing mechanism 221C does not include the relief valve assembly 62 on the piston rod 21. Instead, a support piston 81C, which partially differs from the support piston 81, is provided in place of the support piston 81. The support piston 81C differs from the support piston 81 in that it lacks a passage hole 85. The damping force increasing mechanism 221C does not include the relief valve 82 between the support piston 81C and the intervening member 61.

[0260] The first end portion 22 of the piston rod 21 protrudes from the support piston 81C toward the side of the piston rod 21 axially opposite the piston assembly 17. Furthermore, a nut 91 is screwed into the external thread 54 formed on the outer circumference of the first end portion 22. Consequently, at least the inner circumferences of the intervening member 60, the second damping valve 76, the piston 18, the first damping valve 75, the intervening member 61, and the support piston 81C are axially clamped by the main shaft portion 51 and the nut 91. The support piston 81C is fixed to the piston rod 21.

[0261] The first cylinder 101 is mounted on the support piston 81C in the same manner as the support piston 81. The damping force increasing mechanism 221C includes a cup 100C instead of the cup 100. The cup 100C differs from the cup 100 in that the support piston 81C is provided instead of the support piston 81.

[0262] The damping force increasing mechanism 221C includes a divided piston 143C that is partially different from divided piston 143A, instead of divided piston 143A. The divided piston 143C includes a base member 171C that is partially different from base member 171A, instead of base member 171. The base member 171C includes a main body 181C that is partially different from main body 181A, instead of main body 181A.

[0263] The base member 171C has a connecting portion 182A and a cylindrical portion 183A similar to those of the base member 171. A through-hole 321 is formed in the base member 171C at the radial center of the main body 181C. The through-hole 321 extends axially through the main body 181C. A passage hole 85C is formed in the base member 171C radially outward of the through-hole 321. The passage hole 85C extends axially through the main body 181C. A plurality of passage holes 85C are formed in the main body 181C. The plurality of passage holes 85C are spaced apart in the circumferential direction of the main body 181C. The plurality of passage holes 85C are radially inward of the connecting portion 182A in the base member 171C.

[0264] Also like Figure 10 As shown, the dividing piston 143C includes a relief valve 82C, a mounting bolt 325 , a mounting nut 326 , and a washer 327 .

[0265] The mounting bolt 325 includes a shaft portion 331 and a head portion 332. The outer diameter of the shaft portion 331 is smaller than the outer diameter of the head portion 332. The shaft portion 331 has an external thread 333 formed on its outer peripheral portion on the opposite side from the head portion 332 in the axial direction.

[0266] The relief valve 82C is a disk valve composed of a plurality of stacked annular disks. Figure 9 As shown, the relief valve 82C is arranged at a position on the opposite side of the base member 171C from the locking member 172A in the axial direction.

[0267] Also like Figure 10 As shown, the shaft portion 331 of the mounting bolt 325 is inserted into the radially inner side of the relief valve 82C, the through hole 321 of the base member 171C, and the washer 327 from the axial side of the relief valve 82C opposite to the base member 171C. Furthermore, the mounting nut 326 is screwed into the external thread 333 of the shaft portion 331 protruding from the locking member 172C. Figure 9As shown, the radially inner portion of the relief valve 82C, the radially inner portion of the base member 171C, and the washer 327 are clamped together by the head 332 of the mounting bolt 325 and the mounting nut 326. The outer peripheral portion of the relief valve 82C abuts against the base member 171C, closing the passages within the plurality of passage holes 85C. The outer peripheral portion of the relief valve 82C moves away from the base member 171C, opening the passages within the plurality of passage holes 85C. The head 332 of the mounting bolt 325 has a higher rigidity than the disk that constitutes the relief valve 82C. The head 332 of the mounting bolt 325 prevents excessive deformation of the relief valve 82C. The base member 171C, relief valve 82C, the mounting bolt 325, the washer 327, and the mounting nut 326 constitute the relief valve assembly 62C.

[0268] The base member 171C of the partition piston 143C is fixed to the second cylinder 142 at the body portion 181C, similarly to the body portion 181A of the base member 171A.

[0269] The partitioning piston 143C is fixed to the base member 171C in this manner, and the movable ring 173 and the locking member 172A are attached to the base member 171A in the same manner as the movable ring 173 and the locking member 172A are attached to the base member 171A. As a result, the movable ring 173 is clamped in its axial direction by the cylindrical portion 183A of the base member 171C and the flange portion 202A of the locking member 172A.

[0270] The relief valve assembly 62C is supported by the valve body assembly 31 together with the dividing piston 143C via the second cylinder 142 .

[0271] The dividing piston 143C is supported by the bottom member 12 of the tube 3 via the second cylinder 142, the base adapter 141, and the seat member 32 of the valve body assembly 31. In other words, the second cylinder 142, which has a smaller diameter than the first cylinder 101, is provided in the valve body assembly 31 via the base adapter 141 and supports the dividing piston 143C. The dividing piston 143C and the dividing piston support body 211A are provided in the second chamber 20.

[0272] In the shock absorber 1C, the first cylinder chamber 214, formed by the engagement of the first cylinder 101 with the movable ring 173 of the partitioning piston 143C, is the portion of the first cylinder 101 between the support piston 81C and the partitioning piston 143C. The cylinder outer chamber 215 is the portion of the second chamber 20 excluding the first cylinder chamber 214. In the shock absorber 1C, the portion surrounded by the valve body assembly 31, the base adapter 141, the second cylinder 142, and the partitioning piston 143C constitutes the second cylinder chamber 213.

[0273] In the shock absorber 1C, the damping force increasing mechanism 221C operates similarly to the damping force increasing mechanism 221A of the second embodiment except for the following points with respect to the shock absorber 1A.

[0274] In the damping force increasing mechanism 221A of the second embodiment, when the piston rod 21 is within the retraction stroke within the second predetermined range, the relief valve 82 of the relief valve assembly 62 opens in accordance with the piston speed, allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the passages within the plurality of passage holes 85. Thus, the damping force increasing mechanism 221A of the second embodiment suppresses an excessive increase in the pressure in the first cylinder inner chamber 214.

[0275] In contrast, the damping force increasing mechanism 221C of the fourth embodiment opens the relief valve 82C of the relief valve assembly 62C based on piston speed, allowing the oil L to flow from the first cylinder chamber 214 to the second cylinder chamber 213 of the cylinder outer chamber 215 via the passages within the plurality of passage holes 85C, thereby suppressing excessive pressure increases in the first cylinder chamber 214. The relief valve 82C allows the oil L to flow from the first cylinder chamber 214 to the cylinder outer chamber 215 while suppressing the damping force generated by the flow of the oil L through the passages within the plurality of passage holes 85C during the contraction stroke. The relief valve 82C has a higher rigidity than the second damping valve 76 and is less likely to open. Therefore, the relief valve 82 opens after the second damping valve 76, generating a higher damping force than the second damping valve 76.

[0276] The shock absorber 1C of the fourth embodiment includes a damping force increasing mechanism 221C that increases the damping force when the piston assembly 17 moves toward the second chamber 20. The damping force increasing mechanism 221C of the shock absorber 1C includes a first cylinder 101 coupled to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17; and a partitioning piston 143C that, when the piston assembly 17 moves toward the second chamber 20, enters the first cylinder 101 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0277] Thus, in the shock absorber 1C, the first cylinder 101, which forms the first cylinder inner chamber 214 by causing the partitioning piston 143C to enter when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17. Consequently, the shock absorber 1C can simplify its structure and minimize cost increases. For example, to change the stroke position of the piston rod 21 that increases the damping force, simply change the position of the partitioning piston 143C, thus minimizing cost increases.

[0278] In the shock absorber 1C, the second cylinder 142 supporting the divided piston 143C is provided in the valve body assembly 31 provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the divided piston 143C can be supported with a simple structure.

[0279] Shock absorber 1C supports divided piston 143C by using second cylinder 142, which has a smaller diameter than first cylinder 101. This allows for stable support of divided piston 143C. Furthermore, shaft 126 of bolt 124 of valve body assembly 31 can be extended toward piston assembly 17 to support divided piston 143C.

[0280] The shock absorber 1C has a communication passage 208 between the partition piston 143C and the second cylinder 142, through which air in the second cylinder 142 can flow. Therefore, when the oil L is filled into the tube 3, the shock absorber 1C can smoothly discharge the air in the second cylinder 142 to the outside.

[0281] Shock absorber 1C is provided with a passage 210A in partitioned piston 143C, which connects the outer chamber 215 of second chamber 20 with the inner chamber 214 of first cylinder. A movable ring 173 opens passage 210A when piston assembly 17 moves toward first chamber 19 and blocks passage 210A when piston assembly 17 moves toward second chamber 20. This allows shock absorber 1C to smoothly reduce the damping force of damping force increasing mechanism 221C during the extension stroke, even when damping force is increased by damping force increasing mechanism 221C during the contraction stroke.

[0282] In the shock absorber 1C of the fourth embodiment, the divided piston 143C has a recessed portion 308 at its radial center that is recessed along its axial direction toward the second cylinder 142. Therefore, the shock absorber 1C can reduce the weight of the divided piston 143C.

[0283] The shock absorber 1C of the fourth embodiment is provided with the relief valve 82C in the divided piston 143C, and thus the axial length of the piston rod 21 can be shortened.

[0284] [Fifth embodiment]

[0285] Next, mainly based on Figure 11 and Figure 12 The shock absorber of the fifth embodiment will be described focusing on the parts that are different from the second and fourth embodiments. Parts common to the second and fourth embodiments are denoted by the same names and reference numerals.

[0286] The shock absorber 1D of the fifth embodiment includes a damping force increasing mechanism 221D, which partially differs from the damping force increasing mechanisms 221A and 221C, in place of the damping force increasing mechanisms 221A and 221C. The damping force increasing mechanism 221D includes a support piston 81C, similar to that of the damping force increasing mechanism 221C, on the piston rod 21. The damping force increasing mechanism 221D has a first cylinder 101 mounted on the support piston 81C. Therefore, the damping force increasing mechanism 221D includes a cup 100C.

[0287] The damping force increasing mechanism 221D includes a divided piston 143D that is partially different from divided piston 143A, instead of divided piston 143A. The divided piston 143D includes a base member 171D that is partially different from base member 171A, instead of base member 171. The base member 171D includes a main body 181D that is partially different from main body 181A, instead of main body 181A.

[0288] The base member 171D has a connecting portion 182A and a cylindrical portion 183A similar to those of the base member 171A. A through-hole 321D is formed in the base member 171D at the radial center of the main body 181D. The through-hole 321D extends axially through the main body 181D. The through-hole 321D is located radially inward of the base member 171D relative to the connecting portion 182A.

[0289] The shock absorber 1D includes a valve body assembly 31D that is partially different from the valve body assembly 31, replacing the valve body assembly 31. The damping force increasing mechanism 221D is provided with a relief valve 82D in the valve body assembly 31D. The relief valve 82D is a disk valve formed by stacking multiple annular disks. The relief valve 82D is arranged on the opposite side of the disk valve 123 from the seat member 32 in the axial direction of the seat member 32. Figure 12 As shown, shaft portion 126 of bolt 124 is inserted from below through disk valve 122, seat member 32, disk valve 123, and relief valve 82D. In this state, nut 125 is screwed onto external thread 128 of bolt 124. Thus, bolt 124 and nut 125 attach disk valve 122, disk valve 123, and relief valve 82D to valve seat member 32.

[0290] like Figure 11 As shown, the shock absorber 1D includes a divided piston support body 211D that is partially different from the divided piston support body 211A, replacing the divided piston support body 211A. The divided piston support body 211D includes a base adapter 141D that is partially different from the base adapter 141, replacing the base adapter 141. The base adapter 141D includes a main plate portion 151D that is partially different from the main plate portion 151, replacing the main plate portion 151. A through hole 161D is formed in the radial center of the main plate portion 151D, axially extending through the main plate portion 151D and the press-fit portion 152.

[0291] The outer peripheral portion of the relief valve 82D abuts against the axially opposite side of the press-fit portion 152 of the main plate portion 151D of the base adapter 141D, closing the passage within the through-hole 161D of the main plate portion 151D. The outer peripheral portion of the relief valve 82D separates from the main plate portion 151D, opening the passage within the through-hole 161D. The base adapter 141D and the relief valve 82D constitute the relief valve assembly 62D. The relief valve 82D is assembled to the valve body assembly 31D.

[0292] Dividing piston 143D is supported by bottom member 12 of pipe 3 via second cylinder 142, base adapter 141D, and seat member 32 of valve body assembly 31D. In other words, second cylinder 142, which has a smaller diameter than first cylinder 101, is installed in valve body assembly 31D via base adapter 141D and supports dividing piston 143D. Dividing piston 143D and dividing piston support member 211D are installed in second chamber 20.

[0293] In the shock absorber 1D, the first cylinder chamber 214, formed by the mating of the first cylinder 101 and the movable ring 173 of the partitioning piston 143D, is comprised of the portion of the first cylinder 101 between the support piston 81D and the partitioning piston 143D, the portion within the through-hole 321D of the partitioning piston 143D, the portion within the second cylinder 142, and the portion within the through-hole 161D of the base adapter 141D. The cylinder outer chamber 215 is the portion of the second chamber 20 excluding the first cylinder chamber 214. The passage 210A of the partitioning piston 143 connects the cylinder outer chamber 215 with the first cylinder chamber 214, and the movable ring 173 can open and close this passage 210A.

[0294] In the shock absorber 1D, the damping force increasing mechanism 221D operates similarly to the damping force increasing mechanism 221A of the second embodiment except for the following points.

[0295] In the damping force increasing mechanism 221A of the second embodiment, when the piston rod 21 is within the retraction stroke within the second predetermined range, the relief valve 82 of the relief valve assembly 62 opens in accordance with the piston speed, allowing the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the passages within the plurality of passage holes 85. Thus, the damping force increasing mechanism 221A of the second embodiment suppresses an excessive increase in the pressure in the first cylinder inner chamber 214.

[0296] In contrast, the damping force increasing mechanism 221D opens the relief valve 82D of the valve body assembly 31D according to piston speed, allowing the oil L to flow from the first cylinder inner chamber 214 to the outer cylinder chamber 215 via the passageway in the through-hole 161D of the base adapter 141D, thereby suppressing an excessive increase in the pressure in the first cylinder inner chamber 214. The relief valve 82D allows the oil L to flow from the first cylinder inner chamber 214 to the outer cylinder chamber 215 while suppressing the damping force generated by the flow of oil L through the passageway in the through-hole 161D during the contraction stroke. The relief valve 82D has a higher rigidity than the second damping valve 76 and is difficult to open. Therefore, the relief valve 82D opens after the second damping valve 76, generating a higher damping force than the second damping valve 76.

[0297] The shock absorber 1D of the fifth embodiment includes a damping force increasing mechanism 221D that increases the damping force when the piston assembly 17 moves toward the second chamber 20. The damping force increasing mechanism 221D of the shock absorber 1D includes a first cylinder 101 coupled to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17; and a split piston 143D that, when the piston assembly 17 moves toward the second chamber 20, enters the first cylinder 101 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0298] Thus, in the shock absorber 1D, the first cylinder 101, which forms the first cylinder inner chamber 214 by allowing the partitioning piston 143D to enter when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 at a position closer to the first end 22 than the piston assembly 17. Consequently, the shock absorber 1D can simplify its structure and minimize cost increases. For example, to change the stroke position of the piston rod 21 that increases the damping force, simply change the position of the partitioning piston 143D, thus minimizing cost increases.

[0299] In the shock absorber 1D, the second cylinder 142 supporting the divided piston 143D is provided in the valve body assembly 31D provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the divided piston 143D can be supported with a simple structure.

[0300] Shock absorber 1D supports divided piston 143D by second cylinder 142, which has a smaller diameter than first cylinder 101. This allows for stable support of divided piston 143D. Furthermore, shaft 126 of bolt 124 of valve body assembly 31D can be extended toward piston assembly 17 to support divided piston 143D.

[0301] The shock absorber 1D has a communication path 208 between the partition piston 143D and the second cylinder 142, through which air in the second cylinder 142 can flow. Therefore, when the oil L is filled into the tube 3, the shock absorber 1D can smoothly discharge the air in the second cylinder 142 to the outside.

[0302] The shock absorber 1D is provided with a passage 210A in the partitioned piston 143D, which connects the outer chamber 215 of the second chamber 20 with the first inner chamber 214. A movable ring 173 opens the passage 210A when the piston assembly 17 moves toward the first chamber 19 and blocks the passage 210A when the piston assembly 17 moves toward the second chamber 20. Therefore, even when the damping force increasing mechanism 221D increases the damping force during the contraction stroke, the damping force of the damping force increasing mechanism 221D can be smoothly reduced during the extension stroke.

[0303] In the shock absorber 1D of the fifth embodiment, the divided piston 143D has a concave portion 308 at its radial center that is recessed in its axial direction toward the second cylinder 142. Therefore, the shock absorber 1D can reduce the weight of the divided piston 143D.

[0304] In the shock absorber 1D according to the fifth embodiment, the relief valve 82D is provided in the valve body assembly 31D, and thus the axial length of the piston rod 21 can be shortened.

[0305] [Sixth embodiment]

[0306] Next, mainly based on Figure 13 The shock absorber of the sixth embodiment will be described focusing on the parts that are different from the first embodiment. It should be noted that the parts common to the first embodiment are denoted by the same names and reference numerals.

[0307] The shock absorber 1E of the sixth embodiment includes a damping force increasing mechanism 221E that is partially different from the damping force increasing mechanism 221, instead of the damping force increasing mechanism 221. The damping force increasing mechanism 221E includes a cup-shaped member 100E that is partially different from the cup-shaped member 100, instead of the cup-shaped member 100. The cup-shaped member 100E includes a first cylinder 101E that is partially different from the first cylinder 101, instead of the first cylinder 101. The first cylinder 101E includes a main body portion 111E that is partially different from the main body portion 111, instead of the main body portion 111.

[0308] Similar to the first cylinder 101, the first cylinder 101E has a plurality of grooves 116 extending axially along the inner circumference of one axial end thereof. Also provided on the inner circumference of the other axial end of the first cylinder 101E are grooves 116E extending axially along the inner circumference of the first cylinder 101E. Grooves 116E are provided on the inner circumference of the upper end of the first cylinder 101E. Grooves 116E are recessed from the inner circumference of the first cylinder 101E toward the radially outer side of the first cylinder 101E. The first cylinder 101E has a plurality of grooves 116E arranged at equal intervals along the circumference of the first cylinder 101E. The plurality of grooves 116E have equal lengths from the upper end of the first cylinder 101E. In other words, the plurality of grooves 116E have equal lengths in the axial direction of the first cylinder 101E. The plurality of grooves 116E are formed in the main body 111E.

[0309] The upper end of the first cylinder 101E is pressed into the small-diameter portion 88 of the support piston 81. At this point, the upper end of the support piston 81 abuts against the large-diameter portion 87. This forms the cup 100E. The plurality of grooves 116E extend below the small-diameter portion 88.

[0310] During the contraction stroke of the damping force increasing mechanism 221E within the second predetermined range, when the partitioning piston 143 approaches the support piston 81 within the cup 100E to a point near its limit, the movable ring 173 of the partitioning piston 143 is positioned within the plurality of grooves 116E provided in the first cylinder 101E. Consequently, the oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the plurality of grooves 116E provided in the first cylinder 101E. Consequently, the plurality of grooves 116E suppress an excessive increase in the pressure in the first cylinder inner chamber 214.

[0311] From this position, cup 100E moves toward the extension direction along with piston rod 21. Consequently, movable ring 173 opens passage 210. In this position, as cup 100E moves toward the extension direction along with piston rod 21, oil L flows from outer cylinder chamber 215 to first cylinder chamber 214 via passage 210. Simultaneously, oil L flows from outer cylinder chamber 215 to first cylinder chamber 214 via grooves 116E. This reduces resistance to the extension movement of piston rod 21.

[0312] In the subsequent extension stroke, when the movable ring 173 that divides the piston 143 is located on the opposite side of the support piston 81 from the groove 116E in the first cylinder 101E, the oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 only through the flow path via the passage 210 .

[0313] The shock absorber 1E of the sixth embodiment has a groove 116 extending in the axial direction of the first cylinder 101E on the inner circumference of one axial end of the first cylinder 101E, and a groove 116E extending in the axial direction of the first cylinder 101E on the inner circumference of the other axial end of the first cylinder 101E. As a result, at the beginning of the contraction stroke within the second predetermined range, the rate of change of the damping force becomes gentler due to the groove 116 on the lower end. Since there is no groove in the middle of the axial direction of the first cylinder 101E, the damping force increases in the middle of the contraction stroke within the second predetermined range. At the lower end of the second predetermined range, the increase in damping force is suppressed by the groove 116E. The groove 116E acts as an overflow.

[0314] Furthermore, in the embodiment, hydraulic shock absorbers are described as examples of the shock absorbers 1 and 1A to 1D. However, the above-described structure can also be employed in shock absorbers using water or air as a working fluid.

[0315] Industrial applicability

[0316] According to the shock absorber of the above-described aspect of the present invention, it is possible to suppress an increase in cost.

[0317] Description of Reference Numerals

[0318] 1. 1A~1D: shock absorber

[0319] 3: Tube

[0320] 6: Inner Room

[0321] 17: Piston assembly

[0322] 19: Room 1

[0323] 20: Second Room

[0324] 21: Piston rod

[0325] 22: First end (one end)

[0326] 23: Second end (the other end)

[0327] 31, 31D: Valve body assembly

[0328] 62: Overflow valve assembly (valve assembly)

[0329] 81: Support piston

[0330] 82: Relief valve

[0331] 101: First Cylinder

[0332] 142: Second cylinder (support component)

[0333] 143, 143A ~ 143D: Dividing piston

[0334] 173: Movable ring (movable part)

[0335] 208: Connecting Road

[0336] 210, 210A: Passage

[0337] 214: First cylinder chamber (dividing chamber)

[0338] 221, 221A~221D: Damping force increasing mechanism

Claims

1. A shock absorber, characterized in that: have: The tube, the inside of which becomes the inner chamber; a piston rod, one axial end of which is disposed inside the tube and the other axial end of which is disposed outside the tube; a piston assembly connected to the middle position of the piston rod in the axial direction, dividing the inner chamber into a first chamber on the other end side of the piston rod and a second chamber on the one end side, and generating a damping force when the piston rod moves; a damping force increasing mechanism that increases the damping force when the piston assembly moves toward the second chamber side, The damping force increasing mechanism comprises: a first cylinder connected to a portion of the piston rod closer to the one end than the piston assembly; A partitioning piston is configured to move toward the inside of the first cylinder when the piston assembly moves toward the second chamber, thereby forming a partitioning chamber in the first cylinder.

2. The shock absorber according to claim 1, characterized in that The invention further comprises: a valve body assembly provided on the opposite side of the second chamber from the piston assembly; and a support member provided on the valve body assembly and supporting the partitioning piston.

3. The shock absorber according to claim 2, characterized in that The support member is a second cylinder having a diameter smaller than that of the first cylinder.

4. The shock absorber according to claim 3, characterized in that A communication path through which air in the second cylinder can flow is provided between the partitioning piston and the second cylinder.

5. The shock absorber according to claim 1, characterized in that The damping force increasing mechanism includes a valve assembly connected to a position of the piston rod closer to the one end side than the piston assembly. The first cylinder is connected to the valve assembly.

6. The shock absorber according to claim 5, characterized in that The valve assembly includes: a support piston connected to a position of the piston rod closer to the one end than the piston assembly to support the first cylinder; and a plate-shaped relief valve provided on the support piston.

7. The shock absorber according to claim 1, characterized in that The partitioning piston is provided with a passage connecting the second chamber and the partitioning chamber; and a movable member that opens the passage when the piston assembly moves toward the first chamber and blocks the passage when the piston assembly moves toward the second chamber.

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