Shock absorber

Abstract

This shock absorber is provided with: a tube; a piston rod with one end in the axial direction disposed inside the tube and the other end in the axial direction disposed outside the tube; a piston assembly which is connected to an intermediate position in the axial direction of the piston rod, divides the internal 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 thereof, 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. The damping force increasing mechanism is provided with a first cylinder connected to the piston rod on the side closer to the one end than the piston assembly, and a partition piston that enters the inside of the first cylinder when the piston assembly moves toward the second chamber, forming a partition chamber inside the first cylinder.

Description

shock absorber

[0001] This application claims priority to U.S. patent application Ser. No. 18 / 121,649, filed in the United States on March 15, 2023, the contents of which are incorporated herein by reference.

[0002] There is a shock absorber that increases the damping force when the piston rod reaches a predetermined range on the limit side during the compression stroke in which the piston rod is pushed into the tube (see, for example, Patent Document 1 below).

[0003] U.S. Patent No. 10,107,352

[0004] However, there is a demand for suppressing increases in cost of shock absorbers, and therefore, an object of the present invention is to provide a shock absorber that makes it possible to suppress increases in cost.

[0005] In order to achieve the above object, one aspect of a shock absorber of the present invention includes a tube having an inner chamber, a piston rod having one axial end disposed within the tube and the other axial end disposed outside the tube, a piston assembly connected to the piston rod at an intermediate position in the axial direction to divide 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 of the piston rod and to generate 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. The damping force increasing mechanism includes a first cylinder connected to the piston rod closer to the one end side than the piston assembly, and a partition piston that enters the first cylinder when the piston assembly moves toward the second chamber and forms a partition within the first cylinder.

[0006] According to the shock absorber of the above aspect of the present invention, it is possible to suppress an increase in costs.

[0007] 1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. FIG. 1 is a cross-sectional view of a main portion of the shock absorber according to the first embodiment of the present invention. FIG. 2 is a perspective view showing a base adapter of the shock absorber according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a main portion of the shock absorber according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view of a main portion of the shock absorber according to a second embodiment of the present invention. FIG. 5 is an exploded perspective view showing a compartment piston of the shock absorber according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view of a main portion of the shock absorber according to a third embodiment of the present invention. FIG. 7 is a perspective cross-sectional view showing a movable ring support of the shock absorber according to the third embodiment of the present invention. FIG. 8 is a cross-sectional view of a main portion of the shock absorber according to a fourth embodiment of the present invention. FIG. 9 is an exploded perspective view showing a part of the compartment piston of the shock absorber according to the fourth embodiment of the present invention. FIG. 10 is a cross-sectional view of a main portion of the shock absorber according to a fifth embodiment of the present invention. FIG. 11 is an exploded perspective cross-sectional view showing a body valve assembly of the shock absorber according to the fifth embodiment of the present invention. FIG. 12 is a cross-sectional view of a main portion of the shock absorber according to a sixth embodiment of the present invention.

[0008] [First embodiment] A shock absorber according to a first embodiment of the present invention will be described with reference to Figures 1 to 4. For ease of explanation, the upper side of the drawings will be referred to as "top" and the lower side of the drawings will be referred to as "bottom."

[0009] As shown in FIG. 1 , the shock absorber 1 of the first embodiment is a twin-tube hydraulic shock absorber. The shock absorber 1 is used in a suspension device for a vehicle, specifically an automobile. The shock absorber 1 includes a cylinder 2. The cylinder 2 has a tube 3 and a shell 5. The tube 3 is cylindrical. The shell 5 is cylindrical with a bottom. The inner diameter of the shell 5 is larger than the outer diameter of the tube 3. The tube 3 is disposed radially inside the shell 5. The central axis of the tube 3 and the central axis of the shell 5 coincide. The inside of the tube 3 forms an inner chamber 6. A reservoir chamber 7 is formed between the tube 3 and the shell 5.

[0010] The shell 5 has a body member 11 and a bottom member 12. The body member 11 is cylindrical. The bottom member 12 is circular and fitted inside the lower part of the body member 11. The entire circumference of the bottom member 12 is joined to the body member 11 by welding or the like. The bottom member 12 closes the lower part of the body member 11.

[0011] The shock absorber 1 includes a piston assembly 17. The piston assembly 17 is disposed within 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 fitted within the tube 3. The piston 18 divides the inner chamber 6 of 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 opposite side of the piston 18 from the bottom member 12. In the axial direction of the tube 3, the second chamber 20 is located on the bottom member 12 side of the piston 18. In the cylinder 2, oil L as a working fluid is sealed within the inner chamber 6 of the tube 3. In the cylinder 2, oil L and gas G as working fluids are sealed within a reservoir chamber 7 between the tube 3 and the shell 5.

[0012] The shock absorber 1 includes a piston rod 21. A first end 22, which is one axial end of the piston rod 21, is disposed within the tube 3 of the cylinder 2. A second end 23, which is the other axial end of the piston rod 21, is disposed outside the cylinder 2. A piston assembly 17 is connected to the piston rod 21 at an intermediate position between the first end 22 and the second end 23 in the axial direction, closer to the first end 22. The piston rod 21 is connected to the piston assembly 17 and extends through a first chamber 19 to the outside of the tube 3 and the shell 5, i.e., the cylinder 2. The piston assembly 17 divides the internal chamber 6 into a first chamber 19 on the second end 23 side of the piston rod 21 in the axial direction, and a second chamber 20 on the first end 22 side.

[0013] The shock absorber 1 is connected to the vehicle body with the portion of the piston rod 21 extending from the cylinder 2 disposed at the top, and the body member 11 of the shell 5 disposed at the bottom, and connected to the wheel side of the vehicle.

[0014] The piston 18 is fixed to the piston rod 21. Therefore, the piston 18 and the piston rod 21 move together. In the shock absorber 1, the stroke in which the piston rod 21 moves in a direction to increase the amount of extension from the cylinder 2 is the extension stroke, in which the overall length increases. In the shock absorber 1, the stroke in which the piston rod 21 moves in a direction to decrease the amount of extension from the cylinder 2 is the compression stroke, in which the overall length contracts. In the shock absorber 1, the piston 18 moves toward the first chamber 19 during the extension stroke. In the shock absorber 1, the piston 18 moves toward the second chamber 20 during the compression stroke.

[0015] A rod guide 25 is fitted to the upper opening of the tube 3 and the upper opening of the shell 5. A seal member 26 is fitted to the shell 5 above the rod guide 25. Both the rod guide 25 and the seal member 26 are annular. The piston rod 21 is inserted radially inside the rod guide 25 and the seal member 26. The piston rod 21 slides along the axial direction of each of the rod guide 25 and the seal member 26. The piston rod 21 extends from inside the cylinder 2 to the outside of the cylinder 2 beyond the seal member 26.

[0016] The rod guide 25 restricts radial movement of the piston rod 21 relative to the tube 3 and shell 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. This causes the central axis of the piston rod 21 to coincide with the central 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 seal member 26 is in close contact with the shell 5. The inner periphery of the seal member 26 is in close contact with the outer periphery of the piston rod 21. The piston rod 21 slides relative to the seal member 26 in the axial direction of the seal member 26. The seal member 26 prevents the oil L in the tube 3 and the high-pressure gas G and oil L in the reservoir chamber 7 from leaking to the outside.

[0017] The rod guide 25 has a large diameter portion 28, an intermediate diameter portion 29, and a small diameter portion 30 on its outer periphery. The large diameter portion 28 has an outer diameter larger than that of the intermediate diameter portion 29. The intermediate diameter portion 29 has an outer diameter larger than that of the small diameter portion 30. The intermediate diameter portion 29 of the rod guide 25 is located below the large diameter portion 28. The small diameter portion 30 of the rod guide 25 is located below the intermediate diameter portion 29. The rod guide 25 fits into the inner periphery of the upper end of the tube 3 at the intermediate diameter portion 29. At that time, 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 fits into the inner periphery of the upper part of the body member 11 of the shell 5.

[0018] A body valve assembly 31 is placed on the bottom member 12 of the shell 5. The body valve assembly 31 is provided on the opposite side of the second chamber 20 from the piston assembly 17. The body valve assembly 31 has a seat member 32. The seat member 32 is placed in contact with the upper surface of the bottom member 12 of the shell 5. The seat member 32 is positioned radially relative to the shell 5. The seat member 32 has a large diameter portion 33 and a small diameter portion 34 on its radially outer periphery. The outer diameter of the large diameter portion 33 is larger than the outer diameter of the small diameter portion 34. The large diameter portion 33 of the seat member 32 is located lower than 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 upper small diameter portion 34 of the seat member 32 fits into the inner periphery of the lower end of the tube 3. At this time, the lower end of the tube 3 abuts against the large diameter portion 33 in the axial direction of the tube 3. As a result, the body valve assembly 31 is connected to one axial end of the tube 3.

[0019] A cover 41 is attached to the upper end of the body member 11 of the shell 5. The cover 41 is fitted and fixed to the body member 11. A disk 42 is placed on the seal member 26, and the disk 42 and seal member 26 are fixed to the cylinder 2 by being sandwiched between the cover 41 and the rod guide 25. When attaching the cover 41, the bottom member 12 of the shell 5 is placed on a base, and the disk 42 is pressed against the seal member 26 along the axial direction of the shell 5. This brings the disk 42, seal member 26, rod guide 25, tube 3, seat member 32, and bottom member 12 into axial contact with no gaps between them. This generates an axial force among the disk 42, seal member 26, rod guide 25, tube 3, and seat member 32. In this state, the cover 41 is fixed to the body member 11. This generates an axial force among the disk 42, seal member 26, rod guide 25, tube 3, and seat member 32.

[0020] The piston rod 21 has a main shaft portion 51 and a mounting shaft portion 52. The main shaft portion 51 and the mounting shaft portion 52 are both rod-shaped. The outer diameter of the mounting shaft portion 52 is smaller than the outer diameter 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 relative to the rod guide 25 and the seal member 26 along the axial direction of these members.

[0021] 2, the piston rod 21 has a first end 22 at the end opposite the main shaft 51 in the axial direction of the mounting shaft 52. A male thread 54 is formed on the outer periphery of the first end 22. The portion of the mounting shaft 52 between the main shaft 51 and the first end 22 in the axial direction of the mounting shaft 52 is a fitting shaft 55. The outer periphery of the fitting shaft 55 is a cylindrical surface.

[0022] The piston rod 21 has a mounting shaft portion 52 to which the above-mentioned piston assembly 17, an intervening member 60, an intervening member 61, and a relief valve assembly 62 (valve assembly) are connected.

[0023] A through hole 70 is formed in the radial center of the piston 18 of the piston assembly 17. The through hole 70 passes through 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. A first passage 71 and a second passage 72 are formed in the piston 18 outside the through hole 70 in the radial direction of the piston 18. The first passage 71 and the second passage 72 pass through the piston 18 in the axial direction of the piston 18. A plurality of first passages 71 and a plurality of second passages 72 are formed in the piston 18. The first passages 71 and the second passages 72 are arranged alternately in the circumferential direction of the piston 18. Both the first passage 71 and the second passage 72 can communicate between the first chamber 19 and the second chamber 20.

[0024] The piston assembly 17 has a first damping valve 75 and a second damping valve 76 .

[0025] The first damping valve 75 is a disc valve formed by stacking multiple annular discs. The fitting shaft portion 55 of the piston rod 21 is fitted onto the radially inner side of the first damping valve 75. The first damping valve 75 is disposed on the opposite side of the piston rod 21 from the main shaft portion 51 of the piston 18 in the axial direction of the piston rod 21. During the extension stroke in which the piston rod 21 moves toward the extension side, the outer peripheral portion of the first damping valve 75 separates from the piston 18 to open the first passage 71. As a result, the first damping valve 75 allows hydraulic fluid L to flow from the first chamber 19 to the second chamber 20 through the first passage 71. At this time, the first damping valve 75 suppresses the flow of hydraulic fluid L to generate a damping force. The first damping valve 75 is disposed in the first passage 71 and suppresses the flow of hydraulic fluid L in the first passage 71 during the extension stroke to generate a damping force. The outer peripheral portion of the first damping valve 75 abuts against the piston 18 to close the first passage 71. A fixed orifice (not shown) is provided in a portion between the first damping valve 75 and the piston 18. This fixed orifice allows the oil L to flow from the first chamber 19 to the second chamber 20 via the first passage 71 even when the outer circumferential portion of the first damping valve 75 abuts against the piston 18.

[0026] The second damping valve 76 is a disc valve formed by stacking multiple annular discs. The fitting shaft portion 55 is fitted onto the radially inner side of the second damping valve 76. The second damping valve 76 is disposed between the main shaft portion 51 and the piston 18 in the axial direction of the piston rod 21. During the extension stroke in which the piston rod 21 moves toward the extension side, the outer peripheral portion of the second damping valve 76 separates from the piston 18 to open the second passage 72. This allows the second damping valve 76 to flow hydraulic fluid L from the second chamber 20 to the first chamber 19 through the second passage 72. At this time, the second damping valve 76 suppresses the flow of hydraulic fluid L to generate a damping force. The second damping valve 76 is disposed in the second passage 72 and suppresses the flow of hydraulic fluid L in the second passage 72 during the compression stroke to generate a damping force. The outer peripheral portion of the second damping valve 76 abuts against the piston 18 to close the second passage 72. A fixed orifice (not shown) is provided in a portion between the second damping valve 76 and the piston 18. This fixed orifice allows the oil L to flow from the second chamber 20 to the first chamber 19 via the second passage 72 even when the outer peripheral portion of the second damping valve 76 abuts against the piston 18.

[0027] The piston assembly 17, which includes 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.

[0028] The intervening member 60 has an annular shape. The fitting shaft portion 55 is fitted into the radially inner side of the intervening member 60. The intervening member 60 is arranged on the opposite side of the second damping valve 76 from the piston 18 in the axial direction of the piston rod 21. The intervening member 60 abuts against the second damping valve 76. The intervening member 60 has higher rigidity than the disc that constitutes the second damping valve 76. The intervening member 60 suppresses excessive deformation of the second damping valve 76.

[0029] The intervening member 61 has an annular shape. The fitting shaft portion 55 is fitted into the radially inner side of the intervening member 61. The intervening member 61 is arranged on the opposite side of the first damping valve 75 from the piston 18 in the axial direction of the piston rod 21. The intervening member 61 abuts against the first damping valve 75. The intervening member 61 has higher rigidity than the disc that constitutes the first damping valve 75. The intervening member 61 suppresses excessive deformation of the first damping valve 75.

[0030] The relief valve assembly 62 includes a support piston 81 and a relief valve 82 .

[0031] A through hole 84 is formed in the center of the support piston 81 in the radial direction. The through hole 84 passes through the support piston 81 in the axial direction of the support piston 81. The fitting 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 outside the through hole 84 in the radial direction of the support piston 81. The passage hole 85 passes through the support piston 81 in the axial direction of the support piston 81. A plurality of passage holes 85 are formed in the support piston 81. The plurality of passage holes 85 are arranged at intervals in the circumferential direction of the support piston 81.

[0032] The support piston 81 has, on its outer periphery, a large diameter portion 87 and a small diameter portion 88. The outer diameter of the large diameter portion 87 is larger than the outer diameter of the small diameter portion 88. The support piston 81 has the small diameter portion 88 located below the large diameter portion 87.

[0033] The relief valve 82 is a disk valve formed by stacking multiple annular disks. The fitting shaft portion 55 of the piston rod 21 is fitted into the radially inner side of the relief valve 82. The relief valve 82 is disposed between the intervening 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 to close the passages in the multiple passage holes 85. The outer peripheral portion of the relief valve 82 moves away from the support piston 81 to open the passages in the multiple passage holes 85. The intervening member 61 abuts against the relief valve 82. The intervening member 61 has higher rigidity than the disks that make up the relief valve 82. The intervening member 61 suppresses excessive deformation of the relief valve 82.

[0034] The first end 22 of the piston rod 21 protrudes from the support piston 81 on the opposite side to the relief valve 82 in the axial direction of the piston rod 21. A nut 91 is screwed onto the male threads 54 formed on the outer periphery of the first end 22. As a result, at least the inner peripheries 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 are clamped in the axial direction by the main shaft portion 51 and the nut 91.

[0035] A relief valve assembly 62 including a support piston 81 and a relief valve 82 is attached to the mounting shaft portion 52 of the piston rod 21 with a nut 91. Therefore, the relief valve assembly 62 is provided closer to the body valve assembly 31 than the piston assembly 17 of the piston rod 21. The support piston 81 is fixed to the piston rod 21.

[0036] The relief valve assembly 62 is connected to the piston rod 21 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 closer to the first end 22 than the piston assembly 17, and a relief valve 82 made of a plate-shaped disk provided in contact with the support piston 81.

[0037] A first cylinder 101 is connected to the support piston 81. The support piston 81 and the first cylinder 101 form a cylindrical cup 100 with a bottom. The cup 100 moves integrally with the piston rod 21.

[0038] 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 disposed radially inside the tube 3. The small-diameter portion 88 at the bottom of the support piston 81 is press-fitted into the inner periphery of the upper end of the first cylinder 101. This fixes the first cylinder 101 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. At this time, the central axis of the first cylinder 101 and the central axis of the tube 3 coincide. The first cylinder 101 is disposed 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.

[0039] The first cylinder 101 has a main body portion 111 and an expanded diameter portion 112. The main body portion 111 is cylindrical with a constant inner diameter and a constant outer diameter, and extends from one end to the middle in the axial direction of the first cylinder 101. One axial end of the main body portion 111 of the first cylinder 101 is fitted into the small diameter portion 88 of the support piston 81. The other end of the first cylinder 101 extends downward from the middle in the axial direction of the main body portion 111 away from the support piston 81.

[0040] The expanded diameter portion 112 is provided at the other end, i.e., the lower end, in the axial direction of the first cylinder 101. 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 diameter of the expanded diameter portion 112 increases in the direction away from the main body portion 111 in the axial direction of the first cylinder 101.

[0041] The cup 100 has a first cylinder 101 that opens downward. The first cylinder 101 has a groove 116 formed on the inner periphery of one axial end thereof, the groove 116 extending in the axial direction of the first cylinder 101. The groove 116 is formed on the inner periphery of the lower end of the first cylinder 101. The groove 116 is recessed outward in the radial direction of the first cylinder 101 from the inner periphery of the first cylinder 101. The groove 116 extends from the expanded diameter portion 112 to the lower part of the main body portion 111. The first cylinder 101 has a plurality of grooves 116 formed at equal intervals in the circumferential direction of the first cylinder 101. The grooves 116 each have a different length from the lower end of the first cylinder 101. In other words, the grooves 116 each have a different length in the axial direction of the first cylinder 101.

[0042] The first cylinder 101 is connected to the piston rod 21 on the first end 22 side of the piston assembly 17 via the support piston 81 of the relief valve assembly 62. The relief valve assembly 62 is disposed in the second chamber 20 and connected to the piston rod 21.

[0043] In addition to the seat member 32, the body valve assembly 31 includes a disk valve 122, a disk valve 123, a bolt 124, and a nut 125. The bolt 124 includes a shaft portion 126 and a head portion 127. The outer diameter of the shaft portion 126 is smaller than the outer diameter of the head portion 127. A male thread 128 is formed on the outer periphery of the shaft portion 126 on the side opposite to the head portion 127 in the axial direction.

[0044] The disc valve 122 is provided below the seat member 32. The disc valve 123 is provided above the seat member 32. The shaft 126 of the bolt 124 is inserted from below into the disc valve 122, the seat member 32, and the disc valve 123. In this state, the nut 125 is screwed onto the male thread 128 of the bolt 124. In this way, the bolt 124 and the nut 125 attach the disc valve 122 and the disc valve 123 to the seat member 32.

[0045] The seat member 32 has an annular shape. The seat member 32 has a base portion 131 and a protrusion portion 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 penetrates the base portion 131 in the axial direction of the seat member 32. In the seat member 32, the shank 126 of the bolt 124 is inserted into the through hole 133. In the seat member 32, a passage hole 134 and a passage hole 135 are formed outside the through hole 133 in the radial direction of the seat member 32. The passage hole 134 and the passage hole 135 penetrate the base portion 131 in the axial direction of the seat member 32. The passage hole 135 is located outside the passage hole 134 in the radial direction of the seat member 32. The seat member 32 has a plurality of passage holes 134 and a plurality of passage holes 135 formed therein at intervals in the circumferential direction.

[0046] The protrusion 132 protrudes downward from the outer periphery of the base portion 131. The protrusion 132 is disposed radially outward of the passage hole 135 of the base portion 131. The protrusion 132 of the seat member 32 abuts against the bottom member 12 of the shell 5. The protrusion 132 is formed with a passage groove 136 that penetrates the protrusion 132 in the radial direction of the seat member 32. The seat member 32 is provided with a plurality of passage grooves 136 at equal intervals in the circumferential direction of the seat member 32. This allows the space between the seat member 32 and the bottom member 12 of the shell 5 to communicate with the portion between the body member 11 of the shell 5 and the tube 3. Therefore, the space between the seat member 32 and the bottom member 12 of the shell 5 also constitutes the reservoir chamber 7. The seat member 32 separates the second chamber 20 from the reservoir chamber 7.

[0047] The shock absorber 1 includes a base adapter 141 , a second cylinder 142 (support member), and a partition piston 143 .

[0048] The base adapter 141 has an annular shape and includes a main plate portion 151, a press-fit portion 152, and legs 153.

[0049] The main plate portion 151 is disk-shaped. The press-fit portion 152 is provided at one axial end of the base adapter 141. The press-fit portion 152 protrudes upward from the upper surface of the main plate portion 151. The press-fit portion 152 is cylindrical. The outer diameter of the press-fit portion 152 is smaller than the outer diameter of the main plate portion 151. A through-hole 161 that passes through the main plate portion 151 and the press-fit portion 152 in the axial direction is formed in their radial center. Thus, the main plate portion 151 is disk-shaped with a hole, and the press-fit portion 152 is cylindrical.

[0050] The leg portion 153 is provided at the end 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 periphery of the main plate portion 151. The leg portion 153 is cylindrical. The leg portion 153 is disposed radially outward of the through hole 161 of the main plate portion 151. The radially inner inner periphery 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 periphery of the leg portion 153 increases in diameter as it moves away from the main plate portion 151 in the axial direction.

[0051] A communicating groove 162 is formed in the outer periphery of the main plate 151 and the leg portions 153, penetrating the main plate 151 and the leg portions 153 in the axial direction of the base adapter 141. As shown in FIG. 3 , the communicating groove 162 opens to the outside in the radial direction of the base adapter 141. The communicating groove 162 penetrates the leg portions 153 in the radial direction of the base adapter 141. Therefore, the communicating groove 162 opens to the upper surface of the main plate 151, the outer periphery of the main plate 151, the outer periphery of the leg portions 153, the lower surface of the leg portions 153, and the inner periphery of the leg portions 153. A plurality of communicating grooves 162 are provided in the base adapter 141 at equal intervals in the circumferential direction of the base adapter 141.

[0052] As shown in FIG. 2 , the base adapter 141 is fixed by press-fitting the leg portions 153 into the inner peripheral portion of the tube 3. At this time, the lower ends of the leg portions 153 of the base adapter 141 abut against the upper surface of the outer peripheral portion of the base portion 131 of the seat member 32. At this time, the through holes 161 prevent the base adapter 141 from abutting against the bolts 124 and nuts 125 of the body valve assembly 31. At this time, the leg portions 153 of the base adapter 141 surround the disc valve 123 of the body valve assembly 31 on the radially outer side. In other words, the leg portions 153 are disposed radially outwardly of the disc valve 123 and spaced apart from the disc valve 123. The base adapter 141 abutting against the body valve assembly 31 is provided between the first cylinder 101 and the body valve assembly 31. The base adapter 141 is supported in the axial direction by the body valve assembly 31 and in the radial direction by the tube 3 .

[0053] The second cylinder 142 is cylindrical. The outer diameter of the second cylinder 142 is smaller than the inner diameter of the main body portion 111 of the first cylinder 101. The press-fit portion 152 of the base adapter 141 is press-fitted into the inner periphery of the lower end of the second cylinder 142. At this time, the upper surface of the main plate portion 151 abuts against the lower end of the second cylinder 142. This fixes the second cylinder 142 to the base adapter 141. In this manner, the second cylinder 142 is press-fitted and fixed to the base adapter 141. The second cylinder 142 extends from the base adapter 141 on the side opposite the body valve assembly 31 in the axial direction of the base adapter 141. The base adapter 141 and the second cylinder 142 are provided in the second chamber 20. The second cylinder 142 is supported in the radial direction by the base adapter 141, and in the axial direction by the body valve assembly 31 via the base adapter 141. The communication groove 162 of the base adapter 141 is formed radially outward of the second cylinder 142 of the main plate portion 151.

[0054] As described above, one axial end of the base adapter 141 is provided with the press-fit portion 152 that is press-fit into the second cylinder 142. The other axial end of the base adapter 141 is provided with the leg portion 153 that is placed on the body valve assembly 31. The diameter of the inner periphery of the leg portion 153 increases in the axial direction of the base adapter 141 as it approaches the body valve assembly 31.

[0055] The partition piston 143 is attached to the end of the second cylinder 142 opposite to the base adapter 141 in the axial direction, i.e., the upper end of the second cylinder 142 .

[0056] The partition piston 143 has a base member 171, a locking member 172, and a movable ring 173 (movable member).

[0057] The base member 171 has a main body portion 181 , a flange portion 182 , and a cylindrical portion 183 .

[0058] The main body portion 181 is cylindrical. The flange portion 182 extends radially outward from one axial end of the main body portion 181. The flange portion 182 is annular and extends around the entire circumference of the main body portion 181. The outer diameter of the flange portion 182 is smaller than the inner diameter of the main body portion 111 of the first cylinder 101.

[0059] Axial grooves 191 extending in the axial direction of the main body 181 are formed on the outer periphery of the main body 181 except for the flange portion 182. A plurality of axial grooves 191 are formed in the main body 181 at intervals in the circumferential direction.

[0060] A radial groove 192 that penetrates the flange portion 182 in the radial direction of the flange portion 182 is formed on the axial groove 191 side of the flange portion 182 in the axial direction. A plurality of radial grooves 192 are formed in the flange portion 182 at intervals in the circumferential direction. The same number of radial grooves 192 are formed in the flange portion 182 as the axial grooves 191 in the main body portion 181. Each of the plurality of radial grooves 192 is aligned in phase with the corresponding axial groove 191 in the circumferential direction of the base member 171.

[0061] The tubular portion 183 is cylindrical and has an outer diameter smaller than the outer diameter of the flange portion 182. An axial groove 193 extending in the axial direction is formed on the outer periphery of the tubular portion 183. A plurality of axial grooves 193 are formed in the tubular portion 183 at intervals in the circumferential direction. In the axial direction of the tubular portion 183, the axial groove 193 is formed so as to extend from the end of the tubular portion 183 on the flange portion 182 side to the opposite side from the flange portion 182 in the axial direction.

[0062] The locking member 172 has a fitting portion 201 and a flange portion 202. The fitting portion 201 is cylindrical. The flange portion 202 extends from one axial end of the fitting portion 201 to the outside in the radial direction of the fitting portion 201. The flange portion 202 is annular and extends 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, penetrating the flange portion 202 in the axial direction of the flange portion 202. A plurality of passage holes 205 are formed in the flange portion 202 at intervals in the circumferential direction.

[0063] The movable ring 173 is annular. A portion of the movable ring 173 is broken in the circumferential direction to form a circumferential gap, which allows the movable ring 173 to expand and contract radially. 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 equal to or smaller than the maximum inner diameter of the expanded diameter portion 112 of the first cylinder 101 and larger than the inner diameter of the main body portion 111. The movable ring 173 can contract in diameter until its outer diameter becomes equal to the inner diameter of the main body portion 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 tubular portion 183 of the base member 171. Even in this state, the circumferential gap of the movable ring 173 does not become 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 .

[0064] The partition piston 143 is fixed to the second cylinder 142 by fitting the base member 171 at the main body portion 181 into the inner periphery of the upper end portion of the second cylinder 142. In other words, the base member 171 is fixed to the second cylinder 142 by fitting the main body portion 181 into the inner periphery of the second cylinder 142 on the opposite side of the base adapter 141 in the axial direction. At this time, the flange portion 182 of the base member 171 abuts against the second cylinder 142 in the axial direction of the base member 171. In the base member 171 fixed to the second cylinder 142 in this way, the axial groove 191 and the radial groove 192 form a communication passage 208 that connects the radially inner side of the second cylinder 142 to the radially outer side.

[0065] The partition piston 143 has the movable ring 173 placed on the upper side of the flange portion 182 of the base member 171, which is fixed to the second cylinder 142 in this manner. In other words, the movable ring 173 is disposed on the opposite side of the flange portion 182 from the second cylinder 142 in the axial direction. At this time, the cylindrical portion 183 of the base member 171 is inserted radially inward of the movable ring 173.

[0066] The partition piston 143 is fixed to the base member 171 by press-fitting the locking member 172 into the inner periphery of the cylindrical portion 183 of the base member 171 at the fitting portion 201. At this time, the flange portion 202 of the locking member 172 abuts against the end of the cylindrical portion 183 of the base member 171 on the side opposite the flange portion 182 in the axial direction. In this state, the flange portion 202 of the locking member 172 prevents the movable ring 173 from coming off the cylindrical portion 183. As a result, the movable ring 173 is sandwiched between the flange portion 182 of the base member 171 and the flange portion 202 of the locking member 172 in the axial direction.

[0067] The movable ring 173 is movable in the axial direction between these flange portions 182, 202. When the movable ring 173 moves away from the flange portion 182 in the axial direction, it opens a passage 210 made up of the passages in the multiple 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 in the multiple 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 against the flange portion 182 in the axial direction, it closes the passage 210.

[0068] The partition 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 body valve assembly 31. In other words, the second cylinder 142, which has a smaller diameter than the first cylinder 101, is provided in the body valve assembly 31 via the base adapter 141 and supports the partition piston 143. The second cylinder 142 and the base adapter 141 constitute a partition piston support member 211 that is placed on the body valve assembly 31 and supports the partition piston 143. The partition piston 143 and the partition piston support member 211 are provided in the second chamber 20.

[0069] The area surrounded by the body valve assembly 31, base adapter 141, second cylinder 142, and partition piston 143 forms a second cylinder internal chamber 213. The second cylinder internal 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 internal chamber 213 constitutes a part of the second chamber 20. In other words, the main plate portion 151 and the leg portion 153 of the base adapter 141 are provided with the communication groove 162 that forms the second cylinder internal chamber 213, which is part of the second chamber 20, within the second cylinder 142. The communication passage 208 between the partition piston 143 and the second cylinder 142 communicates the second cylinder internal chamber 213 in the second cylinder 142 with the outside of the second cylinder 142. When air is present in a second cylinder inner chamber 213 inside the second cylinder 142 , the communication passage 208 allows the air to flow to the outside of the second cylinder 142 .

[0070] In the body valve assembly 31, a plurality of passage holes 134 allow the oil L to circulate between the reservoir chamber 7 and the second chamber 20, which includes the second cylinder inner chamber 213. In the body valve assembly 31, a plurality of passage holes 135 allow the oil L to circulate between the reservoir chamber 7 and the second chamber 20, which includes the second cylinder inner chamber 213.

[0071] The disc valve 122 on the reservoir chamber 7 side allows the hydraulic fluid L to flow from the second chamber 20, which includes the second cylinder inner chamber 213, to the reservoir chamber 7 via the passage hole 134. On the other hand, the disc valve 122 restricts the flow of the hydraulic fluid L from the reservoir chamber 7 to the second chamber 20 via the passage hole 134. The disc valve 122 opens during the compression stroke of the shock absorber 1, allowing the hydraulic fluid L to flow mainly from the second chamber 20 to the reservoir chamber 7 and generating a damping force.

[0072] The disc valve 123 on the second cylinder inner chamber 213 side allows the flow of hydraulic fluid L from the reservoir chamber 7 to the second chamber 20 via the passage hole 135. On the other hand, the disc valve 123 restricts the flow of hydraulic fluid L from the second chamber 20 to the reservoir chamber 7 via the passage hole 135. The disc valve 123 constantly communicates between the second chamber 20 and the passage hole 134. The disc valve 123 opens during the extension stroke of the shock absorber 1, allowing the hydraulic fluid L to flow from the reservoir chamber 7 to the second chamber 20 and generating a damping force. Note that the disc valve 123 may also be a suction valve that allows the hydraulic fluid L to flow from the reservoir chamber 7 to the second chamber 20 without substantially generating a damping force.

[0073] The partition piston 143 enters the first cylinder 101 from below through an opening at the lower end of the first cylinder 101 and exits downward.

[0074] Here, when the piston rod 21 is in a first predetermined range in which the cup 100 including the first cylinder 101 is positioned above the partition piston 143 and the cup 100 is not fitted to the partition piston 143, the entire interior of the cup 100 becomes the second chamber 20.

[0075] From this state, during the compression stroke, the piston rod 21 moves into a second predetermined range that is closer to the base adapter 141 than the first predetermined range. The cup 100, which moves integrally with the piston rod 21, then moves the movable ring 173 of the partition piston 143 into the expanded diameter portion 112 of the first cylinder 101 so as to cover the partition piston 143, and then fits the movable ring 173 into the main body portion 111 of the first cylinder 101. At the beginning of this fitting, the movable ring 173 is pressed against the flange portion 182 of the base member 171 by the frictional force with the first cylinder 101 it comes into contact with, as shown in FIG. 2 , to block the passage 210. During the subsequent compression stroke, the movable ring 173 slides within the first cylinder 101 to approach the support piston 81, while remaining pressed against the flange portion 182 and blocking the passage 210.

[0076] When the first cylinder 101 is fitted onto the movable ring 173 of the partition piston 143, the second chamber 20 is divided into a first cylinder inner chamber 214 (partition chamber) inside the first cylinder 101 and an outer cylinder chamber 215 outside the first cylinder 101. The first cylinder inner chamber 214 is the portion inside the first cylinder 101 between the relief valve assembly 62 and the partition piston 143. The outer cylinder chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. The outer cylinder 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 partition piston 143 is a passage that can communicate between the cylinder outer chamber 215 and the first cylinder inner chamber 214, and the movable ring 173 can open and close this passage 210.

[0077] During the compression stroke within the second predetermined range, the movable ring 173 abuts against the flange portion 182 as described above, blocking the passage 210, and the cup 100 moves together with the piston rod 21 toward the base adapter 141. In the upper part of the second predetermined range, the movable ring 173 is located at the position of the plurality of grooves 116 provided in the first cylinder 101, and oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages in the plurality of grooves 116. At this time, as the cup 100 approaches the base adapter 141, the number of grooves 116 that allow oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 decreases, eventually reaching zero. As a result, the cup 100, including the first cylinder 101, and the partition piston 143 gradually increase the damping force. During the subsequent compression stroke, the movable ring 173 slides within the first cylinder 101 to approach the support piston 81, while remaining fitted into the main body portion 111 and blocking the passage 210 to the maximum extent. In other words, the movable ring 173 blocks the passage 210 when the piston assembly 17 moves toward the second chamber 20.

[0078] The relief valve assembly 62, the first cylinder 101 connected to the relief valve assembly 62, and the partition piston 143 constitute a damping force increasing mechanism 221 that increases a 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. In other words, the damping force increasing mechanism 221 includes the relief valve assembly 62 that is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17, and the first cylinder 101 is connected to the relief valve assembly 62. The damping force increasing mechanism 221 includes the first cylinder 101 that is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17, and the partition piston 143 that enters the inside of the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0079] Furthermore, during the compression stroke within the second predetermined range, the cup 100 moves toward the base adapter 141 while the partition piston 143 blocks the passage 210 as described above. At this time, the relief valve 82 opens depending on the piston speed, which is the speed at which the piston rod 21, piston 18, and support piston 81 move relative to the tube 3. This causes hydraulic fluid L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages in the multiple passage holes 85. As a result, the relief valve 82 suppresses an excessive increase in pressure in the first cylinder inner chamber 214. The relief valve 82 suppresses the flow of hydraulic fluid L through the passages in the multiple passage holes 85 that occurs during the compression stroke, thereby generating a damping force and allowing hydraulic fluid L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215. Here, the relief valve 82 has higher rigidity than the second damping valve 76 and is less likely to open. Therefore, the relief valve 82 opens later than the second damping valve 76 and generates a higher damping force than the second damping valve 76 .

[0080] 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. Then, due to friction with the first cylinder 101, the movable ring 173 of the partition piston 143 moves axially away from the flange portion 182 and abuts against the flange portion 202, as shown in FIG. 4 , thereby opening the passage 210. In other words, the movable ring 173 opens the passage 210 as the piston assembly 17 moves toward the first chamber 19. During the subsequent extension stroke, the cup 100 moves away from the base adapter 141 while the movable ring 173 maintains the state in which the passage 210 is open. As the cup 100 moves away from the base adapter 141, it allows oil L to flow from the portion of the cylinder outer chamber 215 between the first cylinder 101 and the second cylinder 142 to the first cylinder inner chamber 214 via the passage 210. This reduces the damping force acting on the extension movement of the piston rod 21.

[0081] During the extension stroke, when the movable ring 173 is located closer to the support piston 81 than all of the grooves 116 in the first cylinder 101, the cup 100 moves the support piston 81 a predetermined distance away from the movable ring 173. This causes the movable ring 173 to position at the groove 116 provided in the first cylinder 101, opening the groove 116 to the first cylinder inner chamber 214. Then, in addition to the flow through the passage 210, oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 through the passages in the groove 116, reducing the damping force acting on the extension movement of the piston rod 21. At this time, the farther the cup 100 is from the base adapter 141, the more of the multiple grooves 116 that allow oil L to flow from the cylinder outer chamber 215 to the first cylinder inner chamber 214. This gradually reduces the damping force acting on the extension movement of the piston rod 21.

[0082] As shown in FIG. 1 , a third cylinder 231 is connected to the small diameter portion 30 of the rod guide 25. The third cylinder 231 is cylindrical. The third cylinder 231 is disposed radially inside the tube 3. The third cylinder 231 is fixed to the rod guide 25 by fitting the inner circumferential portion of its upper end into the small diameter portion 30 of the rod guide 25. At this time, the upper end of the third cylinder 231 abuts against the intermediate diameter portion 29 of the rod guide 25 in the axial direction. At this time, the central axis of the third cylinder 231 and the central axis of the tube 3 coincide. The third cylinder 231 is disposed in the first chamber 19 with a radial gap between it and the tube 3.

[0083] The third cylinder 231 has a main body portion 241 and an expanded diameter portion 242. The main body portion 241 is cylindrical with a constant inner diameter and a constant outer diameter, and is provided from one end to the middle portion in the axial direction of the third cylinder 231. One axial end of the main body portion 241 of the third cylinder 231 is fitted into the small diameter portion 30 of the rod guide 25. The other end of the third cylinder 231 extends downward from the middle portion in the axial direction of the main body portion 241 from the rod guide 25.

[0084] The expanded diameter portion 242 is provided at the other axial end, i.e., the lower end, of the third cylinder 231. 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 diameter of the expanded diameter portion 242 increases in the axial direction of the third cylinder 231, in a direction away from the main body portion 241. The third cylinder 231 opens downward.

[0085] The third cylinder 231 has a groove 246 formed on its inner periphery at one axial end thereof, the groove 246 extending in the axial direction of the third cylinder 231. The groove 246 is formed on the inner periphery at the lower end of the third cylinder 231. The groove 246 is recessed outward in the radial direction of the third cylinder 231 from the inner periphery of the third cylinder 231. The groove 246 extends from the expanded diameter portion 242 to the lower part of the main body portion 241. The third cylinder 231 has a plurality of grooves 246 formed at equal intervals in the circumferential direction of the third cylinder 231. The grooves 246 each have a different length from the lower end of the third cylinder 231. In other words, the grooves 246 each have a different length in the axial direction of the third cylinder 231.

[0086] A buffer piston 250 is provided on the main shaft portion 51 of the piston rod 21. The buffer piston 250 has a first stopper member 251, a first locking ring 252, a second stopper member 253, a second locking ring 254, a ring member 255, and a buffer member 256.

[0087] The first stopper member 251, the first locking ring 252, the second stopper member 253, the second locking ring 254, the ring member 255, and the buffer member 256 are all annular in shape, and all have the main shaft portion 51 passing through them.

[0088] The first locking ring 252 is attached to the main shaft portion 51 while being positioned in the axial direction of the main shaft portion 51 .

[0089] The first stopper member 251 is disposed on the rod guide 25 side of the first locking ring 252 in the axial direction of the piston rod 21. The first stopper member 251 abuts against the first locking ring 252, thereby restricting movement of the piston rod 21 in the axial direction away from the rod guide 25.

[0090] The second stopper member 253 has a cylindrical portion 261 and a flange portion 262 .

[0091] The tubular portion 261 is cylindrical. The flange portion 262 extends radially outward from one axial end of the tubular portion 261. The flange portion 262 is annular and extends around the entire circumference of the tubular portion 261. The outer diameter of the flange portion 262 is smaller than the inner diameter of the main body portion 241 of the third cylinder 231. A radial groove 271 is formed in the flange portion 262 on the axial side of the tubular portion 261, penetrating the flange portion 262 in the radial direction. A plurality of radial grooves 271 are formed in the flange portion 262 at intervals in the circumferential direction.

[0092] The second locking ring 254 is attached to the main shaft 51 and positioned closer to the rod guide 25 than the first stopper member 251 in the axial direction of the main shaft 51. The second stopper member 253 is disposed between the second locking ring 254 and the first stopper member 251 in the axial direction of the piston rod 21. The second stopper member 253 is provided on the main shaft 51 such that the flange portion 262 is farther from the first stopper member 251 than the cylindrical portion 261 is in the axial direction of the piston rod 21. The second stopper member 253 abuts against both the second locking ring 254 and the first stopper member 251, thereby restricting movement of the piston rod 21 to both sides in the axial direction.

[0093] The ring member 255 is annular. The outer diameter of the ring member 255 is equal to the inner diameter of the main body portion 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 diameter 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 axial length of the cylindrical portion 261 of the second stopper member 253 minus the axial length of the flange portion 262. 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 ring member 255 moves away from the first stopper member 251 in the axial direction, it opens a passage 272 made up of the passage in the radial groove 271 of the second stopper member 253, the passage between the ring member 255 and the cylindrical portion 261 of the second stopper member 253, and the passage between the movable ring 173 and the first stopper member 251. When the ring member 255 comes into contact with the first stopper member 251 in the axial direction, it closes the passage 272.

[0094] The buffer member 256 is an elastic member and is disposed on the rod guide 25 side of the second stopper member 253 and the second locking ring 254 in the axial direction of the piston rod 21.

[0095] The buffer piston 250 enters the third cylinder 231 from below through an opening at the lower end of the third cylinder 231 and exits downward.

[0096] Here, when the piston rod 21 is in a first predetermined range in which the ring member 255 of the buffer piston 250 is positioned below the third cylinder 231 and the ring member 255 is not engaged with the third cylinder 231, the entire inside of the third cylinder 231 becomes the first chamber 19.

[0097] From this state, during the extension stroke, the piston rod 21 moves into a third predetermined range that is closer to the rod guide 25 than the first predetermined range. Then, the buffer piston 250, which moves integrally with the piston rod 21, fits into the main body portion 241 of the third cylinder 231 after the ring member 255 enters the enlarged diameter portion 242 of the third cylinder 231. At the beginning of this fitting, the ring member 255 is pressed against the first stopper member 251 by the frictional force with the third cylinder 231 that it comes into contact with. As a result, the ring member 255 abuts against the first stopper member 251 in the axial direction and blocks the passage 272. During the subsequent extension stroke, the ring member 255 slides within the third cylinder 231, moving closer to the rod guide 25 while blocking the passage 272.

[0098] During the extension stroke in the third predetermined range, with the ring member 255 blocking the passage 272 as described above, the buffer piston 250 moves together with the piston rod 21 toward the rod guide 25. In the lower part of the third predetermined range, the ring member 255 is located at the position of the plurality of grooves 246 provided in the third cylinder 231, and oil L flows through the plurality of grooves 246. At this time, as the buffer piston 250 approaches the rod guide 25, the number of open grooves 246 among the plurality of grooves 246 decreases, eventually reaching zero. As a result, the damping force generated by the third cylinder 231 and the buffer piston 250 increases in a stepwise manner.

[0099] At the upper limit position of the third predetermined range, the buffer piston 250 brings the buffer member 256 into contact with the rod guide 25 , elastically deforming the buffer member 256 and thereby mitigating the impact of a collision with the rod guide 25 .

[0100] During the compression stroke within the third predetermined range, the buffer piston 250 moves together with the piston rod 21 in a direction away from the rod guide 25, from a state in which the ring member 255 of the buffer piston 250 is fitted in the third cylinder 231. Then, due to frictional force with the third cylinder 231, the ring member 255 of the buffer piston 250 moves axially away from the first stopper member 251, opening the passage 272. During the subsequent extension stroke, the buffer piston 250 moves in a direction away from the rod guide 25, while maintaining the state in which the ring member 255 opens the passage 272. As the buffer piston 250 moves in a direction away from the rod guide 25, it allows oil L to flow through the passage 272. This reduces the damping force acting on the compression movement of the piston rod 21.

[0101] When the ring member 255 of the buffer piston 250 is moved a predetermined distance away from the rod guide 25 during the compression stroke from a state in which the ring member 255 is closer to the rod guide 25 than all of the grooves 246 in the third cylinder 231, the grooves 246 provided in the third cylinder 231 open. Then, in addition to the flow via the passage 272, oil L flows via the grooves 246, reducing the damping force acting on the compression movement of the piston rod 21. At this time, the farther the buffer piston 250 is from the rod guide 25, the more of the multiple grooves 246 through which oil L flows. This causes the damping force acting on the compression movement of the piston rod 21 to be reduced in stages.

[0102] Next, the main operation of the shock absorber 1 will be described.

[0103] "A compression stroke in which the piston rod 21 is in a first predetermined range in the middle in the axial direction of the tube 3"

[0104] {First Speed ​​Region Where Piston Speed ​​is Slower than First Predetermined Value} In this first speed region of the compression stroke, oil L from the second chamber 20 flows into the first chamber 19 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. Therefore, in the first speed region of the compression stroke, a damping force with orifice characteristics (wherein the damping force is approximately proportional to the square of the piston speed) is generated.

[0105] {Second Speed ​​Region Where Piston Speed ​​is Greater than or Equal to First Predetermined Value} In this second speed region of the compression stroke, oil L from the second chamber 20 flows from the second passage 72 to the first chamber 19 in the piston assembly 17, opening the second damping valve 76. Therefore, in the second speed region of the compression stroke, a damping force is generated by the second damping valve 76 with valve characteristics (the damping force is approximately proportional to the piston speed).

[0106] "Extension stroke in which the piston rod 21 is in the first predetermined range"

[0107] {Third Speed ​​Region Where the Piston Speed ​​is Slower than the Second Predetermined Value} In this third speed region of the extension stroke, the hydraulic oil L from the first chamber 19 flows into the second chamber 20 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. Therefore, in the third speed region of the extension stroke, a damping force with orifice characteristics is generated.

[0108] {Fourth Speed ​​Region Where Piston Speed ​​is Greater than or Equal to Second Predetermined Value} In this fourth speed region of the extension stroke, the hydraulic fluid L from the first chamber 19 flows from the first passage 71 to the second chamber 20 in the piston assembly 17, opening the first damping valve 75. Therefore, in the fourth speed region of the extension stroke, a damping force with valve characteristics is generated by the first damping valve 75.

[0109] "Compression stroke in which the piston rod 21 is in a second predetermined range below the first predetermined range in the axial direction of the tube 3" During this compression stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Then, the cup 100 of the damping force increasing mechanism 221 moves toward the base adapter 141 in the axial direction of the tube 3, fitting the movable ring 173 of the partition piston 143 into the first cylinder 101. Then, in the initial stage, the movable ring 173 is pressed against the flange portion 182 to close the passage 210.

[0110] In this state, the cup 100 moves toward the base adapter 141. Then, 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 into the cylinder outer chamber 215. This increases the damping force generated by the damping force increasing mechanism 221. 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 cylinder outer chamber 215 decreases, eventually reaching zero. This causes the damping force generated by the damping force increasing mechanism 221 to increase in stages, thereby increasing the damping force against the contraction movement of the piston rod 21 in stages. In this way, the damping force generated by the damping force increasing mechanism 221 is added to the damping force generated by the piston assembly 17. Here, at the position where the number of grooves 116 through which the oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 becomes zero, the movable ring 173 is fitted into the main body portion 111 of the first cylinder 101, and blocks the passage 210 most. Therefore, during the compression stroke after the movable ring 173 has set the number of grooves 116 through which the oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 to zero, the oil liquid L flowing from the first cylinder inner chamber 214 to the cylinder outer chamber 215 between the first cylinder 101 and the partition piston 143 is most restricted. This further increases the damping force.

[0111] When the cup 100 moves in a direction approaching the base adapter 141, the relief valve 82 of the relief valve assembly 62 opens depending on the piston speed. Then, oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages in the multiple passage holes 85. This prevents an excessive increase in pressure in the first cylinder inner chamber 214.

[0112] "Extension stroke when the piston rod 21 is in the second predetermined range"

[0113] During this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Then, the cup 100 of the damping force increasing mechanism 221 moves in the axial direction of the tube 3 away from the base adapter 141. Then, at the beginning of this movement, the movable ring 173 opens the passage 210, as shown in FIG. 4 .

[0114] With the passage 210 open in this manner, the cup 100 moves in a direction away from the base adapter 141. Then, oil L in the cylinder outer chamber 215 flows from between the first cylinder 101 and the second cylinder 142 to the first cylinder inner chamber 214 via the passage 210. When the movable ring 173 moves from a state in which it is located on the opposite side of the base adapter 141 from all of the grooves 116 provided in the first cylinder 101 to the position of the groove 116 provided in the first cylinder 101, oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 via the passages in the grooves 116 in addition to the flow via the passage 210. At this time, the farther the cup 100 is from the base adapter 141, the more of the multiple grooves 116 that allow oil L to flow from the cylinder outer chamber 215 to the first cylinder inner chamber 214. This gradually reduces the damping force against the movement of the piston rod 21 in the extension direction.

[0115] "Extension stroke in which the piston rod 21 is in a third predetermined range above the first predetermined range in the axial direction of the tube 3" During this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Then, the buffer piston 250 shown in FIG. 1 moves toward the rod guide 25 in the axial direction of the tube 3, fitting the ring member 255 into the third cylinder 231. Then, at the beginning of this movement, the ring member 255 closes the passage 272.

[0116] With the passage 272 blocked in this manner, the buffer piston 250 moves toward the rod guide 25. Then, the oil L in the third cylinder 231 is throttled by the multiple grooves 246 provided in the third cylinder 231 and flows out of the third cylinder 231. Therefore, the damping force generated by the third cylinder 231 and the buffer piston 250 increases. At this time, as the buffer piston 250 approaches the rod guide 25, the number of grooves 246 through which the oil L flows decreases, eventually reaching zero. This increases the generated damping force in stages, and the damping force against the extension movement of the piston rod 21 also increases in stages. The damping force generated by the buffer piston 250 and the third cylinder 231 increases relative to the damping force generated by the piston assembly 17.

[0117] "Compression stroke when the piston rod 21 is in the third predetermined range" During this compression stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Furthermore, the buffer piston 250 moves in a direction away from the rod guide 25. Then, at the beginning of this stroke, the ring member 255 opens the passage 272.

[0118] With the passage 272 open in this manner, the buffer piston 250 moves in a direction away from the rod guide 25. Then, oil L flows from outside the third cylinder 231 into the third cylinder 231 via the passage 272. When the ring member 255 of the buffer piston 250 passes the position of the groove 246 formed in the third cylinder 231 from a state in which it is closer to the rod guide 25 than all of the grooves 246 formed in the third cylinder 231, oil L flows from outside the third cylinder 231 into the third cylinder 231 via the groove 246 in addition to the flow via the passage 272. At this time, the farther the buffer piston 250 is from the rod guide 25, the more of the multiple grooves 246 through which oil L flows. This causes the damping force against the movement of the piston rod 21 in the retraction direction to decrease in stages.

[0119] The aforementioned U.S. Patent No. 10,107,352 discloses a shock absorber that increases damping force when the piston rod reaches a predetermined limit during the compression stroke of the piston rod being pushed into the tube. This shock absorber includes a cup-shaped insert provided in a base valve assembly, a secondary rod attached to a main piston rod, and a secondary piston assembly attached to the secondary rod. The secondary piston assembly enters the insert to form a compartment within the insert, suppressing hydraulic fluid discharge from the compartment, thereby increasing damping force. This shock absorber has a complex structure in which a secondary rod is attached to a main piston rod, and a secondary piston assembly is attached to the secondary rod. This increases costs. For example, changing the stroke position of the main piston rod at which the damping force is increased requires changing the secondary rod, which also increases costs.

[0120] The shock absorber 1 of the first embodiment comprises a tube 3 whose inside is an inner chamber 6, a piston rod 21 whose first axial end 22 is arranged inside the tube 3 and whose second axial end 23 is arranged outside the tube 3, a piston assembly 17 connected to the piston rod 21 at an intermediate position in the axial direction to divide 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, and which generates a damping force when the piston rod 21 moves, and a damping force increasing mechanism 221 which increases the damping force when the piston assembly 17 moves towards the second chamber 20 side. The shock absorber 1 includes a first cylinder 101 in which the damping force increasing mechanism 221 is connected closer to the first end 22 of the piston rod 21 than the piston assembly 17, and a partition piston 143 that enters the inside of the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0121] In this way, in the shock absorber 1, the first cylinder 101, which forms the first cylinder inner chamber 214 inside by entering the partition piston 143 when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17. This allows the structure of the shock absorber 1 to be simplified and costs to be reduced. For example, when changing the stroke position of the piston rod 21 at which the damping force is increased, it is only necessary to change the position of the partition piston 143, thereby reducing costs.

[0122] In the shock absorber 1, the second cylinder 142 that supports the partition piston 143 is provided in the body valve assembly 31 that is provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the partition piston 143 can be supported with a simple structure.

[0123] The shock absorber 1 supports the partition piston 143 with the second cylinder 142, which has a smaller diameter than the first cylinder 101, and can therefore stably support the partition piston 143. It is also possible to extend the shaft 126 of the bolt 124 of the body valve assembly 31 toward the piston assembly 17 and support the partition piston 143 with this shaft 126.

[0124] The shock absorber 1 is provided with a communication passage 208 between the partition piston 143 and the second cylinder 142, through which air inside the second cylinder 142 can flow. Therefore, the shock absorber 1 can smoothly discharge air inside the second cylinder 142 to the outside of the second cylinder 142 when the tube 3 is filled with oil L.

[0125] In the shock absorber 1, the first cylinder 101 of the damping force increasing mechanism 221 is connected to the relief valve assembly 62, which is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17. Therefore, the shock absorber 1 can have a simplified structure and can suppress an increase in costs.

[0126] The shock absorber 1 includes a support piston 81 in which the relief valve assembly 62 is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17 and supports the first cylinder 101, and a plate-shaped relief valve 82 provided on the support piston 81. Therefore, even if the relief valve 82 is provided in the damping force increasing mechanism 221, the shock absorber 1 can have a simplified structure and prevent costs from increasing.

[0127] In shock absorber 1, partition piston 143 is provided with a passage 210 that connects cylinder outer chamber 215 of second chamber 20 with first cylinder inner chamber 214, and a movable ring 173 that 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 if shock absorber 1 is configured to increase the damping force by damping force increasing mechanism 221 during the compression stroke, it can smoothly decrease the damping force of damping force increasing mechanism 221 during the extension stroke.

[0128] Second Embodiment Next, a shock absorber according to a second embodiment will be described, focusing on differences from the first embodiment, mainly with reference to Figures 5 and 6. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0129] The shock absorber 1A has a damping force increasing mechanism 221A that is partially different from the damping force increasing mechanism 221 in place of the damping force increasing mechanism 221. The damping force increasing mechanism 221A has a partition piston 143A that is partially different from the partition piston 143 in place of the partition piston 143. Like the partition piston 143 of the first embodiment, the partition piston 143A is attached to the end of the second cylinder 142 opposite the base adapter 141 in the axial direction, i.e., to the upper end of the second cylinder 142.

[0130] The partition piston 143A has a base member 171A that is partially different from the base member 171, instead of the base member 171. The base member 171A has a main body portion 181A, a connecting portion 182A, and a cylindrical portion 183A.

[0131] The main body 181A is cylindrical. A recess 301 is formed on one axial side of the main body 181A, recessed toward the other axial side. The recess 301 is provided at the radial center of the main body 181A.

[0132] The connecting portion 182A extends radially outward from one axial end of the main body portion 181A. The connecting portion 182A is annular and extends around the entire circumference of the main body portion 181A. The outer diameter of the connecting portion 182A is smaller than the inner diameter of the main body portion 111 of the first cylinder 101.

[0133] The main body 181A has an axial groove 191, similar to that of the first embodiment, formed on the outer periphery of the main body 181A except for the connecting portion 182A, extending in the axial direction of the main body 181A. The connecting portion 182A has a radial groove 192, similar to that of the first embodiment, formed on the axial groove 191 side in the axial direction, penetrating the connecting portion 182A in the radial direction of the connecting portion 182A.

[0134] The cylindrical portion 183A extends from the outer periphery of the connecting portion 182A to the opposite side of the main body portion 181A in the axial direction of the connecting portion 182A.

[0135] In the axial direction of the base member 171A, the recess 301 of the main body portion 181A is formed from the end face of the main body portion 181A on the cylindrical portion 183A side to the side opposite the cylindrical portion 183A beyond the connecting portion 182A.

[0136] The partition piston 143A has a locking member 172A that is partially different from the locking member 172 instead of the locking member 172.

[0137] The locking member 172A has a contact portion 305, a fitting portion 201A, and a flange portion 202A. The fitting portion 201A is cylindrical.

[0138] The flange portion 202A extends radially outward from one axial end 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.

[0139] The abutting portion 305 extends radially inward from the end of the fitting portion 201A opposite the flange portion 202A in the axial direction. The abutting portion 305 is annular. The inner diameter of the abutting portion 305 is equal to the inner diameter of the opening side of the recess 301.

[0140] As shown in Figure 6, the locking member 172A has a passage groove 205A formed continuous with the flange portion 202A and a 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 the axial direction of the flange portion 202A and in the radial direction of the flange portion 202A. The passage groove 205A penetrates the fitting portion 201A in the radial direction of the fitting portion 201A. The locking member 172A has a plurality of passage grooves 205A formed at intervals around its circumference.

[0141] A portion of the movable ring 173 is broken in the circumferential direction to define a circumferential gap 307, which allows the movable ring 173 to expand and contract in the circumferential and radial directions. 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 can be contracted to have an outer diameter equal to the inner diameter of the main body portion 111 of the first cylinder 101, as shown in FIG. 5 . 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. Even in this state, the circumferential gap 307 of the movable ring 173 does not become zero.

[0142] The partition piston 143A is fixed to the second cylinder 142 by fitting the base member 171A at the main body portion 181A into the inner periphery of the upper end portion of the second cylinder 142. At this time, the connecting portion 182A of the base member 171A abuts against the second cylinder 142 in the axial direction of the base member 171A. As in the first embodiment, the base member 171A fixed to the second cylinder 142 in this manner has the axial groove 191 and the radial groove 192 that form a communication passage 208 that connects the radially inner side of the second cylinder 142 to the radially outer side.

[0143] The partition piston 143A has a movable ring 173 placed on the upper side of the cylindrical portion 183A of the base member 171A in a state where it is fixed to the second cylinder 142 in this manner.

[0144] From this state, the partition piston 143A has the locking member 172A inserted radially inside the movable ring 173 at the fitting portion 201A, and then pressed into the inner periphery of the cylindrical portion 183A of the base member 171A, thereby being fixed to the base member 171A. At this time, the abutment portion 305 of the locking member 172A abuts against the end face of the main body portion 181A of the base member 171A that faces the cylindrical portion 183A in the axial direction. Then, the flange portion 202A of the locking member 172A covers the movable ring 173 on the side opposite the cylindrical portion 183A in the axial direction of the movable ring 173. As a result, the movable ring 173 is sandwiched between the cylindrical portion 183A of the base member 171A and the flange portion 202A of the locking member 172A in the axial direction.

[0145] In the axial direction of the partition piston 143A, the length of the movable ring 173 is shorter than the distance between the cylindrical portion 183A and the flange portion 202A. Therefore, the movable ring 173 is movable in the axial direction between the cylindrical portion 183A and the flange portion 202A.

[0146] When movable ring 173 moves away from cylindrical portion 183A in the axial direction, it opens passage 210A, which is made up of the passages in multiple passage grooves 205A of locking member 172A and the passage between movable ring 173 and cylindrical portion 183A of base member 171A. When movable ring 173 comes into axial contact with cylindrical portion 183A, it closes passage 210A.

[0147] Since the locking member 172A of the partition piston 143A is cylindrical, a recessed portion 308 is formed in the radial center of the end face of the partition piston 143A opposite to the second cylinder 142 in the axial direction of the partition piston 143A, recessed toward the second cylinder 142 along the axial direction of the partition piston 143A. The recessed portion 308 includes a recess 301.

[0148] The partition piston 143A 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 body valve assembly 31. In other words, the second cylinder 142, which has a smaller diameter than the first cylinder 101, is provided in the body valve assembly 31 via the base adapter 141 and supports the partition piston 143A. The partition piston 143A and the partition piston support member 211 are provided in the second chamber 20.

[0149] 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 body valve assembly 31, the base adapter 141, the second cylinder 142, and the partition piston 143A.

[0150] The partition piston 143A enters the first cylinder 101 from below through an opening at the lower end of the first cylinder 101 and exits downward.

[0151] Here, when the piston rod 21 is in a first predetermined range in which the cup 100 including the first cylinder 101 is positioned above the partition piston 143A and the cup 100 is not fitted to the partition piston 143A, the entire interior of the cup 100 becomes the second chamber 20.

[0152] From this state, during the compression stroke, the piston rod 21 moves into a second predetermined range that is closer to the base adapter 141 than the first predetermined range. The cup 100, which moves integrally with the piston rod 21, then moves the movable ring 173 of the partition piston 143A into the expanded diameter portion 112 of the first cylinder 101 so as to cover the partition piston 143A, and then fits the movable ring 173 into the main body portion 111 of the first cylinder 101. At the beginning of this fitting, the movable ring 173 is pressed against the cylindrical portion 183A of the base member 171A by the frictional force with the first cylinder 101 it comes into contact with, blocking the passage 210A. During the subsequent compression stroke, the movable ring 173 slides within the first cylinder 101 to approach the support piston 81, while still pressed against the cylindrical portion 183A and blocking the passage 210A.

[0153] When the first cylinder 101 is fitted into the movable ring 173 of the partition piston 143A, the second chamber 20 is divided into a first cylinder inner chamber 214 inside the first cylinder 101 and an outer cylinder chamber 215 outside the first cylinder 101. The first cylinder inner chamber 214 is the portion inside the first cylinder 101 between the relief valve assembly 62 and the partition piston 143A. The outer cylinder chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. A passage 210A of the partition piston 143A is a passage that can communicate between the outer cylinder chamber 215 and the first cylinder inner chamber 214, and the movable ring 173 can open and close this passage 210A.

[0154] During the compression stroke within the second predetermined range, the cup 100 moves toward the base adapter 141 together with the piston rod 21, with the movable ring 173 abutting against the cylindrical portion 183A and blocking the passage 210A as described above. At the upper part of the second predetermined range, similar to the upper part of the second predetermined range in the first embodiment, the movable ring 173 is positioned at the plurality of grooves 116 provided in the first cylinder 101, and oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages within the plurality of grooves 116. As the cup 100 approaches the base adapter 141, the number of grooves 116 through which oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 decreases, eventually reaching zero. This causes the damping force generated by the cup 100, including the first cylinder 101, and the partition piston 143B to increase stepwise. At a position where the number of grooves 116 through which oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 is set to zero, the movable ring 173 is fitted into the main body portion 111 of the first cylinder 101 and blocks the passage 210A to the maximum extent. During the subsequent compression stroke, the movable ring 173 slides within the first cylinder 101 to approach the support piston 81, while keeping the passage 210A blocked to the maximum extent. In other words, the movable ring 173 blocks the passage 210A when the piston assembly 17 moves toward the second chamber 20.

[0155] The relief valve assembly 62, the first cylinder 101 connected to the relief valve assembly 62, and the partition 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 has the partition piston 143A that enters the inside of the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0156] Furthermore, during the compression stroke within the second predetermined range, with the partition piston 143A blocking the passage 210A as described above, the cup 100 moves toward the base adapter 141. At that time, depending on the piston speed, which is the speed at which the piston rod 21, piston 18, and support piston 81 move relative to the tube 3, the relief valve 82 opens, as in the first embodiment.

[0157] During the extension stroke within the second predetermined range, the cup 100 moves together with the piston rod 21 in a direction away from the base adapter 141. Then, due to friction with the first cylinder 101, the movable ring 173 of the partition piston 143A moves axially away from the cylindrical portion 183A, opening the passage 210A. During the subsequent extension stroke, the cup 100 moves away from the base adapter 141 while the movable ring 173 maintains the state in which the passage 210A is open. As the cup 100 moves away from the base adapter 141, it allows oil L to flow from the portion of the cylinder outer chamber 215 between the first cylinder 101 and the second cylinder 142 to the first cylinder inner chamber 214 via the passage 210A. This reduces the damping force acting on the extension movement of the piston rod 21.

[0158] During the extension stroke from a state in which the movable ring 173 is closer to the support piston 81 than all of the grooves 116 in the first cylinder 101, when the cup 100 moves the support piston 81 a predetermined distance away from the movable ring 173, the movable ring 173 is positioned at the position of the groove 116 provided in the first cylinder 101, opening the groove 116 to the first cylinder inner chamber 214. Then, in addition to the flow via the passage 210A, oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 via the passage in the groove 116, reducing the damping force acting on the extension movement of the piston rod 21. At that time, the multiple grooves 116 gradually reduce the damping force acting on the extension movement of the piston rod 21.

[0159] Next, the main operations of the shock absorber 1A that differ from those of the shock absorber 1 will be described.

[0160] "Compression stroke when the piston rod 21 is in the second predetermined range" During this compression stroke, the piston assembly 17 operates in the same manner as during the first predetermined range. Then, the cup 100 of the damping force increasing mechanism 221A moves toward the base adapter 141 in the axial direction of the tube 3, fitting the movable ring 173 of the partition piston 143A into the first cylinder 101. Then, in the initial stage, the movable ring 173 is pressed against the cylindrical portion 183A of the base member 171A, blocking the passage 210A.

[0161] In this state, the cup 100 moves toward the base adapter 141. Then, the oil L in the first cylinder inner chamber 214 is constricted by the multiple grooves 116 provided in the first cylinder 101 and flows into the cylinder outer chamber 215. Therefore, the damping force generated by the damping force increasing mechanism 221A increases. 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 cylinder outer chamber 215 decreases, eventually reaching zero. This causes the damping force generated by the damping force increasing mechanism 221A to increase in stages, thereby increasing the damping force against the contraction movement of the piston rod 21 in stages. In this way, the damping force generated by the damping force increasing mechanism 221A is added to the damping force generated by the piston assembly 17. Here, at the position where the number of grooves 116 through which the oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 becomes zero, the movable ring 173 is fitted into the main body portion 111 of the first cylinder 101, and blocks the passage 210A most. Therefore, during the compression stroke after the movable ring 173 has set the number of grooves 116 through which the oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 to zero, the oil liquid L flowing from the first cylinder inner chamber 214 to the cylinder outer chamber 215 between the first cylinder 101 and the partition piston 143A is most restricted. This further increases the damping force.

[0162] When the cup 100 moves in a direction approaching the base adapter 141, the relief valve 82 of the relief valve assembly 62 opens depending on the piston speed. Then, oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages in the multiple passage holes 85. This prevents an excessive increase in pressure in the first cylinder inner chamber 214.

[0163] "Extension stroke when the piston rod 21 is in the second predetermined range"

[0164] During this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Then, 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. Then, at the initial stage of this movement, the movable ring 173 opens the passage 210A.

[0165] With the passage 210A open in this manner, the cup 100 moves in a direction away from the base adapter 141. Then, oil L in the cylinder outer chamber 215 flows from between the first cylinder 101 and the second cylinder 142 to the first cylinder inner chamber 214 through the passage 210A. When the movable ring 173 moves from a state in which it is located on the opposite side of the base adapter 141 from all of the grooves 116 provided in the first cylinder 101 to the position of the groove 116 provided in the first cylinder 101, oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 through the passages in the grooves 116 in addition to the flow via the passage 210A. At this time, the farther the cup 100 is from the base adapter 141, the more of the multiple grooves 116 that allow oil L to flow from the cylinder outer chamber 215 to the first cylinder inner chamber 214. This gradually reduces the damping force against the movement of the piston rod 21 in the extension direction.

[0166] 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 shock absorber 1 includes a first cylinder 101 connected to the piston rod 21 closer to the first end 22 than the piston assembly 17, and a partition piston 143A that enters the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0167] In this way, in the shock absorber 1A, the first cylinder 101, which forms the first cylinder inner chamber 214 inside by entering the partition piston 143A when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17. This allows the shock absorber 1A to have a simplified structure and suppress costs. For example, when changing the stroke position of the piston rod 21 at which the damping force is increased, it is only necessary to change the position of the partition piston 143A, thereby suppressing costs.

[0168] In the shock absorber 1A, the second cylinder 142 that supports the partition piston 143A is provided in the body valve assembly 31 that is provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the partition piston 143A can be supported with a simple structure.

[0169] The shock absorber 1A can stably support the partition piston 143A because the second cylinder 142, which has a smaller diameter than the first cylinder 101, supports the partition piston 143A. Note that it is also possible to extend the shaft 126 of the bolt 124 of the body valve assembly 31 toward the piston assembly 17 and support the partition piston 143A with this shaft 126.

[0170] In shock absorber 1A, a communication passage 208 that allows air to flow through the second cylinder 142 is provided between the partition piston 143A and the second cylinder 142. Therefore, in shock absorber 1A, air in the second cylinder 142 can be smoothly discharged to the outside of the second cylinder 142 when the tube 3 is filled with oil L.

[0171] In shock absorber 1A, partition piston 143A is provided with a passage 210A that connects cylinder outer chamber 215 of second chamber 20 with first cylinder inner chamber 214, and a movable ring 173 that opens passage 210A when piston assembly 17 moves toward first chamber 19 and closes passage 210A when piston assembly 17 moves toward second chamber 20. Therefore, even if shock absorber 1A is configured to increase the damping force by damping force increasing mechanism 221A during the compression stroke, it can smoothly decrease the damping force of damping force increasing mechanism 221A during the extension stroke.

[0172] In the shock absorber 1A of the second embodiment, the partition piston 143A has a recessed portion 308 at the radial center that is recessed along the axial direction toward the second cylinder 142. Therefore, the shock absorber 1A can reduce the weight of the partition piston 143A.

[0173] [Third Embodiment] Next, a shock absorber according to a third embodiment will be described, focusing on differences from the first embodiment, mainly with reference to Figures 7 and 8. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0174] The shock absorber 1B of the third embodiment has a movable ring support 211B shown in Figures 7 and 8, which is an integrated unit of the compartment piston support 211 having the base adapter 141 and the second cylinder 142, the base member 171, and the locking member 172 of the first embodiment. The movable ring support 211B is integrally molded by injection molding of a synthetic resin material, for example.

[0175] As shown in FIG. 8, the movable ring support 211B has a support base portion 141B, a support cylindrical portion 142B, a ring support portion 310, and a reinforcing portion 311.

[0176] The support base portion 141B is annular in shape. A communication hole 162B is formed in the support base portion 141B, penetrating the support base portion 141B along the axial direction of the support base portion 141B. 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.

[0177] The support cylindrical portion 142B extends from the inner periphery 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 multiple communication holes 162B of the support base portion 141B are disposed radially outward of the support cylindrical portion 142B. As shown in FIG. 7 , 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 in the support cylindrical portion 142B at the end opposite the support base portion 141B in the axial direction. The communication passage 208B penetrates the support cylindrical portion 142B in the radial direction of the support cylindrical portion 142B.

[0178] The ring support portion 310 is provided at the end of the support cylindrical portion 142B opposite to the support base portion 141B in the axial direction. The ring support portion 310 has a base portion 171B and a locking portion 172B.

[0179] The base portion 171B is provided at the end of the support cylindrical portion 142B opposite the support base portion 141B in the axial direction. The base portion 171B is disk-shaped. 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 of the support cylindrical portion 142B opposite the support base portion 141B in the axial direction. A recess 313 is formed in the radial center of the base portion 171B, recessed toward the support cylindrical portion 142B from the end face opposite the support cylindrical portion 142B in the axial direction.

[0180] The movable ring support 211B has a recessed portion 315 formed by the support base portion 141B, the support cylindrical portion 142B, and the base portion 171B, which is recessed from the end face of the support base portion 141B on the axial side opposite the support cylindrical portion 142B to the base portion 171B. The communication passage 208B formed in the support cylindrical portion 142B opens near the bottom of the recessed portion 315.

[0181] A reinforcing portion 311 is formed in the recessed portion 315 of the movable ring support 211B. The reinforcing portion 311 is in the shape of a triangular plate. The reinforcing portion 311 connects the portion of the support cylindrical portion 142B on the base portion 171B side in the axial direction with the portion of the base portion 171B on the support cylindrical portion 142B side in the axial direction. A plurality of reinforcing portions 311 are formed in the movable ring support 211B at intervals in the circumferential direction. The communicating passages 208B are arranged out of phase with these reinforcing portions 311 in the circumferential direction of the movable ring support 211B.

[0182] The locking portion 172B is provided on the opposite side of the base portion 171B from the support cylindrical portion 142B in the axial direction. The locking portion 172B has a cylindrical portion 183B and a flange portion 202B.

[0183] The cylindrical portion 183B extends in the opposite direction from the support cylindrical portion 142B from the end face of the base portion 171B on the axial side opposite 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.

[0184] The flange portion 202B extends radially outward from the end of the cylindrical portion 183B opposite the base portion 171B in the axial direction of the cylindrical portion 183B. 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.

[0185] A passage groove 205B is formed in the locking portion 172B, continuing from 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. A plurality of passage grooves 205B are formed in the locking portion 172B at intervals around the circumferential direction. This allows the locking portion 172B to be elastically deformed such that the end opposite to the base portion 171B in the axial direction has a smaller diameter overall.

[0186] The movable ring support 211B is fixed by press-fitting the support base portion 141B into the inner periphery of the tube 3. At this time, the lower end of the support base portion 141B abuts against the upper surface of the outer periphery of the base portion 131 of the seat member 32. At this time, the recessed portion 315 prevents the movable ring support 211B from hitting the bolts 124 and nuts 125 of the body valve assembly 31. At this time, the support base portion 141B of the movable ring support 211B surrounds the disc valve 123 of the body valve assembly 31 on the radially outer side. In other words, the support base portion 141B is disposed radially outward of the disc valve 123 and spaced apart from the disc valve 123. The movable ring support 211B is supported by the body valve assembly 31 in the axial direction and by the tube 3 in the radial direction.

[0187] The movable ring support 211B has a support cylindrical portion 142B extending from the support base portion 141B on the opposite side of the support base portion 141B in the axial direction from the body valve assembly 31. The movable ring support 211B has a ring support portion 310 provided at an end of the support cylindrical portion 142B on the opposite side of the axial direction from the body valve assembly 31. The movable ring support 211B is provided in the second chamber 20.

[0188] As described above, one axial end of the movable ring support 211B is provided with the support base portion 141B, which is placed on the body valve assembly 31. The inner periphery of the support base portion 141B increases in diameter in the axial direction of the support base portion 141B as it approaches the body valve assembly 31.

[0189] 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 contracts in diameter until its outer diameter becomes equal to the inner diameter of the main body portion 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 tubular portion 183B of the locking portion 172B. Even in this state, the circumferential gap 307 of the movable ring 173 does not become zero.

[0190] The movable ring 173 is assembled to the locking portion 172B from the side opposite the base portion 171B in the axial direction of the locking portion 172B. 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 opposite the base portion 171B in the axial direction of the locking portion 172B has a smaller diameter. Once the movable ring 173 is assembled, the locking portion 172B returns to its original shape. In this state, the flange portion 202B of the locking portion 172B covers the movable ring 173 on the side opposite the base portion 171B in the axial direction of the movable ring 173. As a result, the movable ring 173 is sandwiched between the base portion 171B and the flange portion 202B of the locking portion 172B in the axial direction.

[0191] 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 is movable in the axial direction between the base portion 171B and the flange portion 202B.

[0192] As described above, the movable ring 173 is movable in the axial direction between the base portion 171B and the flange portion 202B. When the movable ring 173 moves away from the base portion 171B in the axial direction, it opens a passage 210B consisting of the passages in the multiple 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 comes into contact with the base portion 171B in the axial direction, it closes the passage 210B.

[0193] The partition piston 143B is supported on the bottom member 12 of the tube 3 via the support cylindrical portion 142B, the support base portion 141B, and the seat member 32 of the body valve assembly 31. In other words, the support cylindrical portion 142B, which has a smaller diameter than the first cylinder 101, is provided on the body valve assembly 31 via the support base portion 141B and supports the partition piston 143B.

[0194] The area surrounded by the body valve assembly 31, the support base 141B, the support cylindrical portion 142B, and the base 171B of the ring support portion 310 forms a second cylinder internal chamber 213. The second cylinder internal 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 in the communication hole 162B of the support base 141B. The second cylinder internal chamber 213 constitutes a part of the second chamber 20. In other words, the support base 141B is provided with a communication hole 162B that forms the second cylinder internal chamber 213, which is 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 inner chamber 213 inside the support cylindrical portion 142B to the outside of the support cylindrical portion 142B. When air is present in the second cylinder inner chamber 213 inside the movable ring support member 211B, the communication passage 208B allows the air to circulate outside the movable ring support member 211B.

[0195] The partition piston 143B enters the first cylinder 101 from below through an opening at the lower end of the first cylinder 101 and exits downward.

[0196] Here, when the piston rod 21 is in a first predetermined range in which the cup 100 including the first cylinder 101 is positioned above the partition piston 143B and the cup 100 is not fitted to the partition piston 143B, the entire interior of the cup 100 becomes the second chamber 20.

[0197] From this state, during the compression stroke, the piston rod 21 moves into a second predetermined range that is closer to the support base portion 141B than the first predetermined range. The cup 100, which moves integrally with the piston rod 21, then moves the movable ring 173 of the partition piston 143B into the enlarged diameter portion 112 of the first cylinder 101 so as to cover the partition piston 143B, and then fits the movable ring 173 into the main body portion 111 of the first cylinder 101. At the beginning of this fitting, the movable ring 173 is pressed against the base portion 171B of the movable ring support 211B by the frictional force with the first cylinder 101 it comes into contact with, blocking the passage 210B. During the subsequent compression stroke, the movable ring 173 slides within the first cylinder 101 to approach the support piston 81, while remaining pressed against the base portion 171B and blocking the passage 210B.

[0198] When the first cylinder 101 is fitted into the movable ring 173 of the partition piston 143B, the second chamber 20 is divided into a first cylinder inner chamber 214 inside the first cylinder 101 and an outer cylinder chamber 215 outside the first cylinder 101. The first cylinder inner chamber 214 is the portion inside the first cylinder 101 between the relief valve assembly 62 and the partition piston 143B. The outer cylinder chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. A passage 210B of the partition piston 143B is a passage that can communicate between the outer cylinder chamber 215 and the first cylinder inner chamber 214, and the movable ring 173 can open and close this passage 210B.

[0199] During the compression stroke within the second predetermined range, the cup 100 moves toward the support base portion 141B together with the piston rod 21, with the movable ring 173 abutting against the base portion 171B and blocking the passage 210B as described above. At 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 at the plurality of grooves 116 provided in the first cylinder 101, and oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages within the plurality of grooves 116. As the cup 100 approaches the support base portion 141B, the number of grooves 116 through which oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 decreases, eventually reaching zero. This allows the cup 100, including the first cylinder 101, and the partition piston 143B to generate a gradually increasing damping force. At a position where the number of grooves 116 through which oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 is set to zero, the movable ring 173 is fitted into the main body portion 111 of the first cylinder 101 and blocks the passage 210B to the maximum extent. During the subsequent compression stroke, the movable ring 173 slides within the first cylinder 101 to approach the support piston 81, while keeping the passage 210B blocked to the maximum extent. In other words, the movable ring 173 blocks the passage 210B when the piston assembly 17 moves toward the second chamber 20.

[0200] The relief valve assembly 62, the first cylinder 101 connected to the relief valve assembly 62, and the partition 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 has the partition piston 143B that enters the inside of the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0201] During the compression stroke within the second predetermined range, the cup 100 moves toward the support base portion 141B while the partition piston 143B closes the passage 210B as described above. At that time, the relief valve 82 opens depending on the piston speed, which is the speed at which the piston rod 21, the piston 18, and the support piston 81 move relative to the tube 3.

[0202] During the extension stroke within the second predetermined range, the cup 100 moves together with the piston rod 21 in a direction away from the support base portion 141B. Then, due to friction with the first cylinder 101, the movable ring 173 of the partition piston 143B moves axially away from the base portion 171B, opening the passage 210B. During the subsequent extension stroke, the cup 100 moves away from the support base portion 141B while the movable ring 173 maintains the state in which the passage 210B is open. As the cup 100 moves away from the support base portion 141B, it allows oil L to flow from the portion of the cylinder outer chamber 215 between the first cylinder 101 and the support cylindrical portion 142B to the first cylinder inner chamber 214 via the passage 210B. This reduces the damping force acting on the extension movement of the piston rod 21.

[0203] During the extension stroke from a state in which the movable ring 173 is closer to the support piston 81 than all of the grooves 116 in the first cylinder 101, when the cup 100 moves the support piston 81 a predetermined distance away from the movable ring 173, the movable ring 173 is positioned at the position of the groove 116 provided in the first cylinder 101, opening the groove 116 to the first cylinder inner chamber 214. Then, in addition to the flow via the passage 210B, oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 via the passage in the groove 116, reducing the damping force acting on the extension movement of the piston rod 21. At that time, the multiple grooves 116 gradually reduce the damping force acting on the extension movement of the piston rod 21.

[0204] Next, the main operations of the shock absorber 1B that differ from those of the shock absorber 1 will be described.

[0205] "Compression stroke when the piston rod 21 is in the second predetermined range" During this compression stroke, the piston assembly 17 operates in the same manner as during the first predetermined range. Then, the cup 100 of the damping force increasing mechanism 221B moves toward the support base portion 141B in the axial direction of the tube 3, fitting the movable ring 173 of the partition piston 143B into the first cylinder 101. Then, in the initial stage, the movable ring 173 is pressed against the base portion 171B to close the passage 210B.

[0206] In this state, the cup 100 moves toward the support base portion 141B. Then, the oil L in the first cylinder inner chamber 214 is constricted by the multiple grooves 116 provided in the first cylinder 101 and flows into the cylinder outer chamber 215. Therefore, the damping force generated by the damping force increasing mechanism 221B increases. As the cup 100 approaches the support base portion 141B, the number of grooves 116 that allow the oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 decreases, eventually reaching zero. This causes the damping force generated by the damping force increasing mechanism 221B to increase in stages, thereby increasing the damping force against the contraction movement of the piston rod 21 in stages. In this way, the damping force generated by the damping force increasing mechanism 221B is added to the damping force generated by the piston assembly 17. Here, at the position where the number of grooves 116 through which oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 becomes zero, the movable ring 173 is fitted into the main body portion 111 of the first cylinder 101, and blocks the passage 210B most. Therefore, during the compression stroke after the movable ring 173 has set the number of grooves 116 through which oil liquid L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 to zero, the oil liquid L flowing from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via the first cylinder 101 and the partition piston 143B is most restricted. This further increases the damping force.

[0207] When the cup 100 moves in a direction approaching the support base portion 141B, the relief valve 82 of the relief valve assembly 62 opens depending on the piston speed. Then, oil L flows from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages in the multiple passage holes 85. This prevents an excessive increase in pressure in the first cylinder inner chamber 214.

[0208] "Extension stroke when the piston rod 21 is in the second predetermined range"

[0209] During this extension stroke, the piston assembly 17 operates in the same manner as in the first predetermined range. Then, the cup 100 of the damping force increasing mechanism 221B moves in the axial direction of the tube 3 away from the support base portion 141B. Then, at the initial stage of this movement, the movable ring 173 opens the passage 210B.

[0210] With the passage 210B open, the cup 100 moves away from the support base 141B. Then, the oil L in the cylinder outer chamber 215 flows from between the first cylinder 101 and the support cylindrical portion 142B to the first cylinder inner chamber 214 through the passage 210B. When the movable ring 173 moves from a position on the opposite side of the support base 141B from all of the grooves 116 provided in the first cylinder 101 to the position of the groove 116 provided in the first cylinder 101, the oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 through the passages in the grooves 116 in addition to the flow through the passage 210B. At this time, the farther the cup 100 moves from the support base 141B, the more of the grooves 116 that allow the oil L to flow from the cylinder outer chamber 215 to the first cylinder inner chamber 214. This gradually reduces the damping force against the extension movement of the piston rod 21.

[0211] 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 shock absorber 1B also includes a first cylinder 101 connected to the piston rod 21 closer to the first end 22 than the piston assembly 17, and a partition piston 143B that enters the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0212] In this way, in shock absorber 1B, the first cylinder 101, which forms the first cylinder inner chamber 214 inside by entering the partition piston 143B when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17. This allows the structure of shock absorber 1B to be simplified and costs to be reduced. For example, when changing the stroke position of the piston rod 21 at which the damping force is increased, it is sufficient to change the position of the partition piston 143B, thereby reducing costs.

[0213] In the shock absorber 1B, the movable ring support 211B that supports the movable ring 173 is provided on the body valve assembly 31 that is provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the partition piston 143B can be supported with a simple structure.

[0214] The shock absorber 1B supports the partition piston 143B with the support cylindrical portion 142B, which has a smaller diameter than the first cylinder 101, and therefore can stably support the partition piston 143B.

[0215] The shock absorber 1B has a communication passage 208B in the support cylindrical portion 142B that allows air to circulate inside the support cylindrical portion 142B. Therefore, when the oil liquid L is filled into the tube 3, the shock absorber 1B can smoothly discharge air inside the support cylindrical portion 142B to the outside of the movable ring support member 211B.

[0216] Shock absorber 1B is provided with a passage 210B in partition piston 143B that connects cylinder outer chamber 215 of second chamber 20 with first cylinder inner chamber 214, and a movable ring 173 that 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. Therefore, even if shock absorber 1B is configured to increase the damping force by damping force increasing mechanism 221B during the compression stroke, it can smoothly decrease the damping force of damping force increasing mechanism 221B during the extension stroke.

[0217] In the shock absorber 1B, the movable ring support 211B that supports the movable ring 173 is integrally formed by injection molding of a synthetic resin material, thereby reducing the cost of the shock absorber 1B.

[0218] [Fourth embodiment] Next, a shock absorber according to a fourth embodiment will be described, focusing on differences from the second embodiment, mainly with reference to Figures 9 and 10. Note that parts common to the second embodiment will be designated by the same names and symbols.

[0219] The shock absorber 1C of the fourth embodiment has a damping force increasing mechanism 221C that is partially different from the damping force increasing mechanism 221A in place of the damping force increasing mechanism 221A. The damping force increasing mechanism 221C does not have a relief valve assembly 62 provided on the piston rod 21, and a support piston 81C that is partially different 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 does not have a passage hole 85. The damping force increasing mechanism 221C does not have a relief valve 82 provided between the support piston 81C and the intervening member 61.

[0220] The first end 22 of the piston rod 21 protrudes from the support piston 81C on the side opposite to the piston assembly 17 in the axial direction of the piston rod 21. A nut 91 is screwed onto a male thread 54 formed on the outer periphery of the first end 22. As a result, at least the inner peripheries 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 clamped in the axial direction by the main shaft portion 51 and the nut 91. The support piston 81C is fixed to the piston rod 21.

[0221] The first cylinder 101 is attached to the support piston 81C in the same manner as the attachment to the support piston 81. In the damping force increasing mechanism 221C, a cup 100C is provided in place of the cup 100, which differs from the cup 100 in that the support piston 81C is provided instead of the support piston 81.

[0222] The damping force increasing mechanism 221C has a partition piston 143C that is partially different from the partition piston 143A in place of the partition piston 143A. The partition piston 143C has a base member 171C that is partially different from the base member 171A in place of the base member 171. The base member 171C has a main body portion 181C that is partially different from the main body portion 181A in place of the main body portion 181A.

[0223] 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 radial center of a main body portion 181C in the base member 171C. The through hole 321 penetrates the main body portion 181C in the axial direction of the main body portion 181C. A passage hole 85C is formed in the base member 171C outside the through hole 321 in the radial direction of the main body portion 181C. The passage hole 85C penetrates the main body portion 181C in the axial direction of the main body portion 181C. A plurality of passage holes 85C are formed in the main body portion 181C. The plurality of passage holes 85C are arranged at intervals in the circumferential direction of the main body portion 181C. The plurality of passage holes 85C are arranged inside the connecting portion 182A in the radial direction of the base member 171C.

[0224] As also shown in FIG. 10, the compartment piston 143C includes a relief valve 82C, a mounting bolt 325, a mounting nut 326, and a washer 327.

[0225] The mounting bolt 325 has 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. A male thread 333 is formed on the outer periphery of the shaft portion 331 on the side opposite to the head portion 332 in the axial direction.

[0226] The relief valve 82C is a disk valve configured by stacking a plurality of annular disks. As shown in Figure 9, the relief valve 82C is disposed on the opposite side of the base member 171C from the locking member 172A in the axial direction.

[0227] As shown in FIG. 10 , the shaft 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 axially opposite side of the relief valve 82C to the base member 171C. Then, the mounting nut 326 is threaded onto the male thread 333 of the shaft 331 protruding from the locking member 172C. As a result, as shown in FIG. 9 , the radially inner portion of the relief valve 82C, the radially inner portion of the base member 171C, and the washer 327 are clamped to 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 to close the passages in the multiple passage holes 85C. The outer peripheral portion of the relief valve 82C separates from the base member 171C to open the passages in the multiple passage holes 85C. The head 332 of the mounting bolt 325 has higher rigidity than the disk that constitutes the relief valve 82C. The head 332 of the mounting bolt 325 suppresses excessive deformation of the relief valve 82C. The base member 171C, the relief valve 82C, the mounting bolt 325, the washer 327, and the mounting nut 326 constitute the relief valve assembly 62C.

[0228] The partition piston 143C is fixed to the second cylinder 142 at the main body portion 181C of the base member 171C in the same manner as the main body portion 181A of the base member 171A.

[0229] The partition piston 143C has the movable ring 173 and the locking member 172A attached to the base member 171C in the same manner as the movable ring 173 and the locking member 172A are attached to the base member 171A, while the base member 171C is fixed to the second cylinder 142. As a result, the movable ring 173 is sandwiched in the axial direction between the cylindrical portion 183A of the base member 171C and the flange portion 202A of the locking member 172A.

[0230] The relief valve assembly 62C is supported by the body valve assembly 31 via the second cylinder 142 together with the partition piston 143C.

[0231] The partition piston 143C 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 body valve assembly 31. In other words, the second cylinder 142, which has a smaller diameter than the first cylinder 101, is provided on the body valve assembly 31 via the base adapter 141 and supports the partition piston 143C. The partition piston 143C and the partition piston support member 211A are provided in the second chamber 20.

[0232] In the shock absorber 1C, a first cylinder inner chamber 214 is formed by fitting the first cylinder 101 to the movable ring 173 of the partition piston 143C, and is the portion between the support piston 81C and the partition piston 143C inside the first cylinder 101. A cylinder outer chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. In the shock absorber 1C, the portion surrounded by the body valve assembly 31, the base adapter 141, the second cylinder 142, and the partition piston 143C becomes the second cylinder inner chamber 213.

[0233] In the shock absorber 1C, the damping force increasing mechanism 221C operates in the same manner as the damping force increasing mechanism 221A of the second embodiment, except for the following point.

[0234] In the damping force increasing mechanism 221A of the second embodiment, during the compression stroke when the piston rod 21 is in the second predetermined range, depending on the piston speed, the relief valve 82 of the relief valve assembly 62 opens to allow oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages in the multiple passage holes 85. In this way, the damping force increasing mechanism 221A of the second embodiment suppresses an excessive increase in pressure in the first cylinder inner chamber 214.

[0235] In contrast, in the damping force increasing mechanism 221C of the fourth embodiment, depending on the piston speed, the relief valve 82C of the relief valve assembly 62C opens to allow hydraulic fluid L to flow from the first cylinder inner chamber 214 to the second cylinder inner chamber 213 of the cylinder outer chamber 215 through the passages in the multiple passage holes 85C, thereby suppressing an excessive increase in pressure in the first cylinder inner chamber 214. The relief valve 82C suppresses the flow of hydraulic fluid L through the passages in the multiple passage holes 85C that occurs during the compression stroke, thereby generating a damping force while allowing hydraulic fluid L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215. Here, the relief valve 82C has higher rigidity than the second damping valve 76 and is therefore less likely to open. Therefore, the relief valve 82C opens later than the second damping valve 76 and generates a higher damping force than the second damping valve 76.

[0236] 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 shock absorber 1C further includes a first cylinder 101 connected to the piston rod 21 closer to the first end 22 than the piston assembly 17, and a partition piston 143C that enters the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0237] In this way, in the shock absorber 1C, the first cylinder 101, which forms the first cylinder inner chamber 214 inside by entering the partition piston 143C when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17. This allows the shock absorber 1C to have a simplified structure and reduce costs. For example, when changing the stroke position of the piston rod 21 at which the damping force is increased, it is sufficient to change the position of the partition piston 143C, thereby reducing costs.

[0238] In the shock absorber 1C, the second cylinder 142 that supports the partition piston 143C is provided in the body valve assembly 31 that is provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the partition piston 143C can be supported with a simple structure.

[0239] The shock absorber 1C can stably support the partition piston 143C because the second cylinder 142, which has a smaller diameter than the first cylinder 101, supports the partition piston 143C. It is also possible to extend the shaft 126 of the bolt 124 of the body valve assembly 31 toward the piston assembly 17 and support the partition piston 143C with this shaft 126.

[0240] In shock absorber 1C, a communication passage 208 that allows air to flow through the second cylinder 142 is provided between the partition piston 143C and the second cylinder 142. Therefore, in shock absorber 1C, air in the second cylinder 142 can be smoothly discharged to the outside of the second cylinder 142 when the tube 3 is filled with oil L.

[0241] The shock absorber 1C is provided with a partition piston 143C having a passage 210A that connects the cylinder outer chamber 215 of the second chamber 20 with the first cylinder inner chamber 214, and a movable ring 173 that opens the passage 210A when the piston assembly 17 moves toward the first chamber 19 and closes the passage 210A when the piston assembly 17 moves toward the second chamber 20. Therefore, even if the shock absorber 1C is configured to increase the damping force by the damping force increasing mechanism 221C during the compression stroke, the damping force of the damping force increasing mechanism 221C can be smoothly reduced during the extension stroke.

[0242] In the shock absorber 1C of the fourth embodiment, the partition piston 143C has a recessed portion 308 at the radial center that is recessed along the axial direction toward the second cylinder 142. Therefore, in the shock absorber 1C, the partition piston 143C can be made lighter.

[0243] In the shock absorber 1C of the fourth embodiment, the relief valve 82C is provided in the partition piston 143C, so that the axial length of the piston rod 21 can be shortened.

[0244] [Fifth Embodiment] Next, a shock absorber according to a fifth embodiment will be described, focusing on differences from the second and fourth embodiments, mainly with reference to Figures 11 and 12. Note that parts common to the second and fourth embodiments will be designated by the same names and symbols.

[0245] The shock absorber 1D of the fifth embodiment has a damping force increasing mechanism 221D that is partially different from the damping force increasing mechanisms 221A, 221C in place of the damping force increasing mechanisms 221A, 221C. The damping force increasing mechanism 221D has a support piston 81C similar to the damping force increasing mechanism 221C attached to the piston rod 21. In the damping force increasing mechanism 221D, a first cylinder 101 is attached to the support piston 81C. Therefore, the damping force increasing mechanism 221D is provided with a cup 100C.

[0246] The damping force increasing mechanism 221D has a partition piston 143D that is partially different from the partition piston 143A in place of the partition piston 143A. The partition piston 143D has a base member 171D that is partially different from the base member 171A in place of the base member 171. The base member 171D has a main body portion 181D that is partially different from the main body portion 181A in place of the main body portion 181A.

[0247] 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 radial center of the main body portion 181D of the base member 171D. The through hole 321D penetrates the main body portion 181D in the axial direction of the main body portion 181D. The through hole 321D is located more inward than the connecting portion 182A in the radial direction of the base member 171D.

[0248] The shock absorber 1D has a body valve assembly 31D that is partially different from the body valve assembly 31, instead of the body valve assembly 31. The damping force increase mechanism 221D includes a relief valve 82D provided in the body valve assembly 31D. The relief valve 82D is a disc valve configured by stacking multiple annular discs. The relief valve 82D is located on the opposite side of the disc valve 123 from the seat member 32 in the axial direction of the seat member 32. As shown in FIG. 12 , the shaft 126 of the bolt 124 is inserted from below into the disc valve 122, seat member 32, disc valve 123, and relief valve 82D. In this state, a nut 125 is threaded onto the male thread 128 of the bolt 124. The bolt 124 and the nut 125 thereby attach the disc valve 122, disc valve 123, and relief valve 82D to the seat member 32.

[0249] 11 , shock absorber 1D has a partition piston support 211D that is partially different from partition piston support 211A in place of partition piston support 211A. Partition piston support 211D has a base adapter 141D that is partially different from base adapter 141 in place of base adapter 141. Base adapter 141D has a main plate portion 151D that is partially different from main plate portion 151 in place of main plate portion 151. A through hole 161D that axially penetrates main plate portion 151D and press-fit portion 152 is formed in the radial center of main plate portion 151D.

[0250] The relief valve 82D has an outer peripheral portion that abuts against the axial side of the main plate portion 151D of the base adapter 141D opposite the press-fit portion 152, thereby closing the passage within the through-hole 161D of the main plate portion 151D. The relief valve 82D has an outer peripheral portion that moves away from the main plate portion 151D, thereby opening the passage within the through-hole 161D. The base adapter 141D and the relief valve 82D constitute a relief valve assembly 62D. The relief valve 82D is incorporated into the body valve assembly 31D.

[0251] The partition piston 143D is supported on the bottom member 12 of the tube 3 via the second cylinder 142, the base adapter 141D, and the seat member 32 of the body valve assembly 31D. In other words, the second cylinder 142, which has a smaller diameter than the first cylinder 101, is provided on the body valve assembly 31D via the base adapter 141D and supports the partition piston 143D. The partition piston 143D and the partition piston support member 211D are provided in the second chamber 20.

[0252] In shock absorber 1D, a first cylinder inner chamber 214 is formed by fitting the first cylinder 101 into the movable ring 173 of the partition piston 143D. This first cylinder inner chamber 214 is made up of the portion of the first cylinder 101 between the support piston 81D and the partition piston 143D, the portion inside the through hole 321D of the partition piston 143D, the portion inside the second cylinder 142, and the portion inside the through hole 161D of the base adapter 141D. A cylinder outer chamber 215 is the portion of the second chamber 20 excluding the first cylinder inner chamber 214. A passage 210A of the partition piston 143 is a passage that can communicate between the cylinder outer chamber 215 and the first cylinder inner chamber 214, and the movable ring 173 can open and close this passage 210A.

[0253] In the shock absorber 1D, a damping force increasing mechanism 221D operates in the same manner as the damping force increasing mechanism 221A of the second embodiment, except for the following point.

[0254] In the damping force increasing mechanism 221A of the second embodiment, during the compression stroke when the piston rod 21 is in the second predetermined range, depending on the piston speed, the relief valve 82 of the relief valve assembly 62 opens to allow oil L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 through the passages in the multiple passage holes 85. In this way, the damping force increasing mechanism 221A of the second embodiment is configured to suppress an excessive increase in pressure in the first cylinder inner chamber 214.

[0255] In response to this, the damping force increasing mechanism 221D opens the relief valve 82D of the body valve assembly 31D depending on the piston speed, allowing hydraulic fluid L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 via a passage in the through-hole 161D of the base adapter 141D, thereby suppressing an excessive increase in pressure in the first cylinder inner chamber 214. The relief valve 82D suppresses the flow of hydraulic fluid L via the passage in the through-hole 161D that occurs during the compression stroke, allowing hydraulic fluid L to flow from the first cylinder inner chamber 214 to the cylinder outer chamber 215 while generating a damping force. Here, the relief valve 82D has higher rigidity than the second damping valve 76 and is therefore less likely to open. Therefore, the relief valve 82D opens later than the second damping valve 76, generating a higher damping force than the second damping valve 76.

[0256] 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 shock absorber 1D also includes a first cylinder 101 connected to the piston rod 21 closer to the first end 22 than the piston assembly 17, and a partition piston 143D that enters the first cylinder 101 when the piston assembly 17 moves toward the second chamber 20 to form a first cylinder inner chamber 214 within the first cylinder 101.

[0257] In this way, in shock absorber 1D, the first cylinder 101, into which the partition piston 143D enters to form the first cylinder inner chamber 214 when the piston assembly 17 moves toward the second chamber 20, is connected to the piston rod 21 closer to the first end 22 than the piston assembly 17. Therefore, shock absorber 1D can simplify its structure and reduce costs. For example, when changing the stroke position of the piston rod 21 at which the damping force is increased, it is sufficient to change the position of the partition piston 143D, thereby reducing costs.

[0258] In the shock absorber 1D, the second cylinder 142 that supports the partition piston 143D is provided in the body valve assembly 31D that is provided on the opposite side of the second chamber 20 from the piston assembly 17. Therefore, the partition piston 143D can be supported with a simple structure.

[0259] The shock absorber 1D can stably support the partition piston 143D because the second cylinder 142, which has a smaller diameter than the first cylinder 101, supports the partition piston 143D. Note that it is also possible to extend the shaft 126 of the bolt 124 of the body valve assembly 31D toward the piston assembly 17 and support the partition piston 143D with this shaft 126.

[0260] In shock absorber 1D, a communication passage 208 that allows air to flow through the second cylinder 142 is provided between the partition piston 143D and the second cylinder 142. Therefore, in shock absorber 1D, air in the second cylinder 142 can be smoothly discharged to the outside of the second cylinder 142 when the tube 3 is filled with oil L.

[0261] In shock absorber 1D, a partition piston 143D is provided with a passage 210A that connects the cylinder outer chamber 215 of the second chamber 20 with the first cylinder inner chamber 214, and a movable ring 173 that opens the passage 210A when the piston assembly 17 moves toward the first chamber 19 and closes the passage 210A when the piston assembly 17 moves toward the second chamber 20. Therefore, even if shock absorber 1D is configured to increase the damping force by the damping force increasing mechanism 221D during the compression stroke, it can smoothly reduce the damping force of the damping force increasing mechanism 221D during the extension stroke.

[0262] In the shock absorber 1D of the fifth embodiment, the partition piston 143D has a recessed portion 308 at the radial center that is recessed along the axial direction toward the second cylinder 142. Therefore, the shock absorber 1D can reduce the weight of the partition piston 143D.

[0263] In the shock absorber 1D of the fifth embodiment, the relief valve 82D is provided in the body valve assembly 31D, so that the axial length of the piston rod 21 can be shortened.

[0264] [Sixth Embodiment] Next, a shock absorber according to a sixth embodiment will be described, focusing on differences from the first embodiment, mainly with reference to Fig. 13. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0265] The shock absorber 1E of the sixth embodiment has 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 has a cup 100E that is partially different from the cup 100, instead of the cup 100. The cup 100E has a first cylinder 101E that is partially different from the first cylinder 101, instead of the first cylinder 101. The first cylinder 101E has a main body portion 111E that is partially different from the main body portion 111, instead of the main body portion 111.

[0266] Similar to the first cylinder 101, the first cylinder 101E has a plurality of grooves 116 extending in the axial direction of the first cylinder 101E on its inner periphery at one axial end. The first cylinder 101E also has a groove 116E extending in the axial direction of the first cylinder 101E on its inner periphery at the other axial end. The groove 116E is provided on the inner periphery at the upper end of the first cylinder 101E. The groove 116E is recessed radially outward from the inner periphery of the first cylinder 101E. The first cylinder 101E has a plurality of grooves 116E formed at equal intervals around the circumference of the first cylinder 101E. The grooves 116E have the same length from the upper end of the first cylinder 101E. In other words, the grooves 116E have the same length in the axial direction of the first cylinder 101E. A plurality of grooves 116E are formed in the main body portion 111E.

[0267] The upper end of the first cylinder 101E is press-fitted into the small diameter portion 88 of the support piston 81. At this time, the upper end of the support piston 81 abuts against the large diameter portion 87. This forms the cup 100E. The multiple grooves 116E extend below the small diameter portion 88.

[0268] In the damping force increasing mechanism 221E, when the partition piston 143 approaches the support piston 81 within the cup 100E to its limit during the compression stroke within the second predetermined range, the movable ring 173 of the partition piston 143 is positioned at the position of the plurality of grooves 116E provided in the first cylinder 101E. Then, 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. As a result, the plurality of grooves 116E suppress an excessive increase in pressure in the first cylinder inner chamber 214.

[0269] From this state, the cup 100E moves in the extension direction together with the piston rod 21. As a result, the movable ring 173 opens the passage 210. When the cup 100E moves in the extension direction together with the piston rod 21 in this state, the oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 via the passage 210. At the same time, the oil L flows from the cylinder outer chamber 215 to the first cylinder inner chamber 214 via the multiple grooves 116E. This reduces the resistance force to the movement of the piston rod 21 in the extension direction.

[0270] During the subsequent extension stroke, when the movable ring 173 of the partition piston 143 is positioned on the opposite side of the support piston 81 from the groove 116E in the first cylinder 101E, 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.

[0271] In the shock absorber 1E of the sixth embodiment, a groove 116 extending in the axial direction of the first cylinder 101E is provided on the inner periphery of one axial end of the first cylinder 101E, and a groove 116E extending in the axial direction of the first cylinder 101E is provided on the inner periphery of the other axial end of the first cylinder 101E. As a result, the rate of change in the damping force is gentler at the start of the compression stroke in the second predetermined range due to the groove 116 on the lower end side. Because there is no groove in the axial middle of the first cylinder 101E, the damping force increases at the middle position of the compression stroke in the second predetermined range. At the lower end of the second predetermined range, the groove 116E suppresses the increase in damping force. The groove 116E serves as a relief.

[0272] In the embodiment, hydraulic shock absorbers are shown as examples of shock absorbers 1, 1A to 1D, but the above structure can also be applied to shock absorbers that use water or air as the working fluid.

[0273] According to the shock absorber according to the above aspect of the present invention, it is possible to suppress an increase in costs.

[0274] 1, 1A to 1D... shock absorber, 3... tube, 6... inner chamber, 17... piston assembly, 19... first chamber, 20... second chamber, 21... piston rod, 22... first end (one end), 23... second end (other end), 31, 31D... body valve assembly, 62... relief valve assembly (valve assembly), 81... support piston, 82... relief valve, 101... first cylinder, 142... second cylinder (support member), 143, 143A to 143D... partition piston, movable ring... 173 (movable member), 208... communicating passage, 210, 210A... passage, 214... first cylinder inner chamber (partition chamber), 221, 221A to 221D... damping force increasing mechanism.

Claims

1. a tube whose inner side is an inner chamber; a piston rod having one axial end disposed within the tube and the other axial end disposed outside the tube; a piston assembly connected to the piston rod at an intermediate position 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, The damping force increasing mechanism is a first cylinder connected to the piston rod closer to the one end than the piston assembly; a partition piston that advances into the first cylinder when the piston assembly moves toward the second chamber to form a partition chamber within the first cylinder; a body valve assembly provided on an opposite side of the second chamber from the piston assembly; a support member provided on the body valve assembly and supporting the compartment piston; Equipped with Shock absorber.

2. The support member is a second cylinder having a smaller diameter than the first cylinder. The shock absorber according to claim 1.

3. a communication passage through which air in the second cylinder can flow is provided between the partition piston and the second cylinder; 3. The shock absorber according to claim 2.

4. the damping force increasing mechanism includes a valve assembly connected to the piston rod closer to the one end than the piston assembly and connected to the first cylinder, The valve assembly includes: a support piston connected to the piston rod closer to the one end than the piston assembly and supporting the first cylinder; a plate-shaped relief valve provided on the support piston; Equipped with the relief valve opens during the retraction stroke of the piston rod to suppress an excessive increase in pressure in the first cylinder. The shock absorber according to claim 1.

5. The compartment piston has a passageway communicating the second chamber with the partitioned chamber; a movable member that opens the passage when the piston assembly moves toward the first chamber and closes the passage when the piston assembly moves toward the second chamber; are provided, The shock absorber according to claim 1.