Buffer

Abstract

To provide a buffer that can restrain a decrease in productivity.SOLUTION: A buffer comprises: a piston 9 partitioning the inside of a cylinder 4 into two chambers 11 and 12; a piston rod 8 of which one end side is fixed to the piston 9, and of which the other end side extends from the cylinder 4; a device 58 provided on one side of the piston 9; a piston passage 50 provided in the piston 9; a rod passage 57 provided in the piston rod 8, and for guiding working fluid to the device 58; and an orifice mechanism 112 for guiding the working fluid to the rod passage 57 from the chamber 11. The orifice mechanism 112 comprises: an introduction member 102 comprising a gap 110 communicating with the rod passage 57 on an inner peripheral side; a cutout member 103 comprising a cutout part 121 for guiding the working fluid to the gap 110 from the chamber 11; and a retainer 104 supporting the cutout member 103 with respect to the introduction member 102, and of which at least a portion has a smaller diameter than that of the cutout part 121.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Among shock absorbers, there are shock absorbers having a variable damping force mechanism that varies the damping force characteristics in accordance with the vibration state (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6942185 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for suppressing a decrease in productivity in shock absorbers.

[0005] The present invention provides a shock absorber that makes it possible to suppress a decrease in productivity. [Means for solving the problem]

[0006] The present invention comprises a cylinder in which a working fluid is sealed, a piston that divides the inside of the cylinder into two chambers, a piston rod having one end fixed to the piston and the other end extending from the cylinder, a device provided on one side of the piston, a piston passage provided in the piston, a rod passage provided in the piston rod for directing the working fluid to the device, and an orifice mechanism for directing the working fluid from the chamber to the rod passage, wherein the orifice mechanism includes an introduction member having a gap on its inner peripheral side that communicates with the rod passage, a notched member having a notch that directs the working fluid from the chamber to the gap, and a retainer that supports the notched member relative to the introduction member and has at least a portion smaller in diameter than the notch. Effect of the Invention

[0007] According to the present invention, it is possible to suppress a decrease in productivity. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view showing a main part of a shock absorber according to a first embodiment of the present invention. [Diagram 3] 1 is a half-side cross-sectional view showing a main part of a shock absorber according to a first embodiment of the present invention. [Figure 4] FIG. 2 is a plan view showing a cut-out disk of the shock absorber of the first embodiment according to the present invention. [Diagram 5] FIG. 6 is a half-side cross-sectional view showing a main part of a shock absorber according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a half-side cross-sectional view showing a main part of a shock absorber according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a plan view showing a backup disk of a shock absorber according to a third embodiment of the present invention. [Figure 8] FIG. 11 is a plan view showing a cut-out disk of a shock absorber according to a third embodiment of the present invention. [Figure 9] FIG. 11 is a plan view showing a retainer of a shock absorber according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] A shock absorber according to a first embodiment of the present invention will be described below with reference to Figs.

[0010] The shock absorber 1 of the first embodiment is a hydraulic shock absorber that uses oil liquid L as the working fluid. As shown in FIG. 1, the shock absorber 1 has a twin-cylinder cylinder 4 having an inner cylinder 2 and an outer cylinder 3. The outer cylinder 3 has a larger diameter than the inner cylinder 2 and is arranged coaxially with the inner cylinder 2 so as to cover the inner cylinder 2. A reservoir chamber 5 is formed between the inner cylinder 2 and the outer cylinder 3. Note that the embodiment is not limited to the twin-cylinder type and can also be used for a single-cylinder type shock absorber.

[0011] The shock absorber 1 has a piston rod 8 and a piston 9. The piston 9 is connected to a first end portion on one axial side of the piston rod 8. The piston 9 moves integrally with the piston rod 8. The piston rod 8 is disposed on the central axis of the inner cylinder 2 and the outer cylinder 3, and a first end portion on one axial end of the piston rod 8 is inserted into the inner cylinder 2 and the outer cylinder 3, and a second end portion on the other axial end of the piston rod 8 extends from the inner cylinder 2 and the outer cylinder 3 to the outside. In other words, the first end portion on one axial end of the piston rod 8 is inserted into the cylinder 4, and a second end portion on the other axial end of the piston rod 8 extends from the cylinder 4 to the outside.

[0012] The piston 9 is slidably fitted in the inner tube 2 of the cylinder 4, and divides the inner tube 2 of the cylinder 4 into two chambers: a first chamber 11 and a second chamber 12. In other words, the piston 9 is slidably provided in the cylinder 4, and is connected to one end of a piston rod 8 whose other end extends to the outside of the cylinder 4. The piston rod 8 is disposed so as to pass through the first chamber 11 of the first chamber 11 and the second chamber 12, and therefore the first chamber 11 is the rod side chamber in which the piston rod 8 is mainly disposed in the shock absorber 1.

[0013] Oil L as a working fluid is sealed in the inner tube 2 of the cylinder 4, and oil L as a working fluid and high-pressure (about 20 to 30 atmospheres) gas G are sealed in the reservoir chamber 5 between the inner tube 2 and the outer tube 3 in the cylinder 4. That is, the working fluid is sealed in the cylinder 4 having the inner tube 2 and the outer tube 3. Note that air at atmospheric pressure may be sealed in the reservoir chamber 5 instead of the high-pressure gas G.

[0014] The shock absorber 1 has a rod guide 15, a seal member 16, and a friction member 17. The shock absorber 1 also has a base valve 18. The rod guide 15 is disposed at an end position of the cylinder 4 on the side where the piston rod 8 protrudes outward, and has a stepped shape, with the large diameter side being fitted inside the outer cylinder 3 and the small diameter side being fitted inside the inner cylinder 2. The seal member 16 is disposed at an end of the cylinder 4, outside the rod guide 15 in the axial direction of the cylinder 4. The friction member 17 is disposed between the seal member 16 and the rod guide 15. The base valve 18 is disposed at an end of the cylinder 4 on the opposite side to the rod guide 15, the seal member 16, and the friction member 17 in the axial direction.

[0015] The rod guide 15, the seal member 16, and the friction member 17 are all annular. The piston rod 8 is slidably inserted through the rod guide 15, the seal member 16, and the friction member 17. The rod guide 15 supports the piston rod 8 so that it can move in the axial direction while restricting its radial movement, and guides the movement of the piston rod 8. The seal member 16 has an inner periphery that slides against the outer periphery of the piston rod 8 that moves in the axial direction, thereby preventing the oil liquid L in the inner cylinder 2 and the gas G and oil liquid L in the reservoir chamber 5 in the outer cylinder 3 from leaking to the outside. The friction member 17 has an inner periphery that slides against the outer periphery of the piston rod 8, thereby generating frictional resistance in the piston rod 8. The friction member 17 is not intended for sealing purposes.

[0016] The outer tube 3 of the cylinder 4 is composed of a cylindrical body member 21 and a bottom cover member 22, and the bottom cover member 22 is fitted to one end of the body member 21 in the axial direction. The bottom cover member 22 has a bottom cover portion 23 and a rod-shaped portion 24. The bottom cover portion 23 is fitted to the inner periphery of the body member 21 at its outer periphery. The rod-shaped portion 24 extends from the center of the bottom cover portion 23 in the radial direction to the opposite side of the body member 21. The bottom cover member 22 is fixed to the body member 21 by welding so as to be in a sealed state with the bottom cover portion 23 fitted to the body member 21. A mounting eye 25 is fixed to the opposite side of the bottom cover portion 23 of the rod-shaped portion 24 by welding. Of the first chamber 11 and the second chamber 12, the second chamber 12 on the bottom cover portion 23 side of the cylinder 4 is the bottom side chamber in the cylinder 4.

[0017] The body member 21 has an opening 27 on the side opposite the bottom cover member 22, and has an engagement portion 28 at this opening 27. The above-mentioned seal member 16 and rod guide 15 are fitted into the opening 27 side of the body member 21. The engagement portion 28 protrudes radially inward from the end position of the opening 27 in the body member 21, and holds the seal member 16 between itself and the rod guide 15.

[0018] A base body 30 of the base valve 18 is disposed inside the bottom cover portion 23. The base body 30 defines the second chamber 12 in the cylinder 4 and the above-mentioned reservoir chamber 5. The base body 30 has a stepped shape with one axial side having a smaller diameter than the other side. The larger diameter side of the base body 30 is placed on the bottom cover portion 23 and positioned in the radial direction.

[0019] The inner cylinder 2 of the cylinder 4 has a cylindrical shape. One axial end of the inner cylinder 2 is supported in a fitted state by the small diameter side of the base body 30 of the base valve 18, and the other axial end is supported in a fitted state by the small diameter side of the rod guide 15 located inside the opening 27 of the outer cylinder 3.

[0020] In the base body 30 of the base valve 18, an insertion hole 29 penetrating in the axial direction is formed in the center in the radial direction, and around this insertion hole 29, flow passages 31, 32 penetrating the base body 30 in the axial direction are formed. These flow passages 31, 32 can communicate with the second chamber 12 in the inner cylinder 2 and the reservoir chamber 5 between the outer cylinder 3 and the inner cylinder 2. In addition, in the base body 30, a disk valve 33 is disposed on the opposite side to the bottom cover part 23, and a disk valve 34 is disposed on the bottom cover part 23 side. The disk valve 33 is a check valve and can open and close the outer flow passage 31. The disk valve 34 is a damping valve and can open and close the inner flow passage 32. The disk valves 33, 34 are attached to the base body 30 by clamping their radially inner parts with rivets 35 inserted into the insertion hole 29.

[0021] The disc valve 34 allows the flow of oil L from the second chamber 12 to the reservoir chamber 5 through a passage hole (not shown) of the disc valve 33 and the flow passage 32 of the base body 30 to generate a damping force, while restricting the flow of oil L in the opposite direction. Conversely, the disc valve 33 allows the flow of oil L from the reservoir chamber 5 to the second chamber 12 without resistance through the flow passage 31 of the base body 30, while restricting the flow of oil L in the opposite direction. When the piston rod 8 moves to the compression side increasing the amount of entry into the cylinder 4 and the piston 9 moves to the second chamber 12 side to increase the pressure in the second chamber 12, the disc valve 34 opens the flow passage 32, and at that time serves as a compression side damping valve that generates a damping force. In addition, when the piston rod 8 moves to the extension side, which increases the amount of protrusion from the cylinder 4, and the piston 9 moves toward the first chamber 11, causing the pressure in the second chamber 12 to decrease, the disc valve 33 opens the flow passage 31. At that time, the disc valve 33 functions as a suction valve that allows the oil L to flow from the reservoir chamber 5 into the second chamber 12 without generating any substantial damping force.

[0022] When the piston rod 8 moves to the extension side and the amount of protrusion from the cylinder 4 increases, the oil L flows from the reservoir chamber 5 through the flow passage 31 to the second chamber 12 while opening the disc valve 33. Conversely, when the piston rod 8 moves to the contraction side and the amount of insertion into the cylinder 4 increases, the oil L flows from the second chamber 12 through the flow passage 32 to the reservoir chamber 5 while opening the disc valve 34.

[0023] Incidentally, the damping force on the extension side may be actively generated by the disk valve 33 as a check valve. Also, these disk valves 33 and 34 may be eliminated and replaced with orifices.

[0024] The piston rod 8 has a mounting shaft portion 40 and a main shaft portion 41. The mounting shaft portion 40 is a portion to which the piston 9 is fixed, and is formed on one end side of the piston rod 8 at the tip side of the insertion into the cylinder 4. The main shaft portion 41 is a portion of the piston rod 8 other than the mounting shaft portion 40, and has a larger outer diameter than the mounting shaft portion 40. The end surface 41a of the main shaft portion 41 on the mounting shaft portion 40 side is flat and extends perpendicularly to the central axis of the piston rod 8. The main shaft portion 41 of the piston rod 8 is slidably inserted into the rod guide 15, the seal member 16, and the friction member 17. A part of the main shaft portion 41 on the other axial side of the mounting shaft portion 40 on one axial side of the piston rod 8 extends from the cylinder 4 via the rod guide 15, the seal member 16, and the friction member 17.

[0025] As shown in FIG. 2, the piston 9 is provided with a piston passage 47 having a plurality of passage holes 45 (only one is shown in FIG. 2 because it is a cross section) and an annular groove 46 that connects the passage holes 45, and a piston passage 50 having a plurality of passage holes 48 (only one is shown in FIG. 2 because it is a cross section) and an annular groove 49 that connects the passage holes 48. Both the piston passage 47 and the piston passage 50 are provided in the piston 9, and both can connect the first chamber 11 and the second chamber 12. The piston 9 is provided with the same number of passage holes 45 and passage holes 48. The passage holes 45 are formed at equal pitches in the circumferential direction of the piston 9, with one passage hole 48 between adjacent ones.

[0026] The piston passage 47 opens radially outward at one axial side (first chamber 11 side) of the piston 9 and opens radially inward at the other axial side (second chamber 12 side). The shock absorber 1 has a damping force generating mechanism 52 that is provided in the piston passage 47 and opens and closes the piston passage 47 to generate a damping force. The damping force generating mechanism 52 is disposed on the second chamber 12 side of the piston 9 in the axial direction.

[0027] The piston passage 50 opens radially outward at the other axial side (second chamber 12 side) of the piston 9 and opens radially inward at one axial side (first chamber 11 side). The shock absorber 1 is provided with a damping force generating mechanism 53 that is provided in the piston passage 50 and opens and closes the piston passage 50 to generate a damping force. The damping force generating mechanism 53 is disposed on the first chamber 11 side of the piston 9 in the axial direction.

[0028] When the piston 9 moves toward the first chamber 11, that is, during the extension stroke in which the piston rod 8 increases the extension amount from the cylinder 4, the damping force generating mechanism 53 provided for the piston passage 50 closes the piston passage 50. On the other hand, the movement of the piston 9 causes the oil L to pass through the piston passage 47, open the damping force generating mechanism 52 provided for the piston passage 47, and flow from the first chamber 11, which is one of the first chamber 11 and the second chamber 12, to the second chamber 12, which is the other. In other words, the piston passage 47 allows the working fluid to flow out from the first chamber 11, which is one of the first chamber 11 and the second chamber 12 in the cylinder 4, when the piston 9 moves in one direction. The piston passage 47 constitutes an extension-side flow passage through which the oil L flows out from the first chamber 11 during the extension stroke. The damping force generating mechanism 52 provided for the piston passage 47 is an extension-side damping force generating mechanism that suppresses the flow of the oil L in the extension-side piston passage 47 to generate a damping force.

[0029] When the piston 9 moves toward the second chamber 12, that is, during the compression stroke in which the piston rod 8 increases the amount of entry into the cylinder 4, the damping force generating mechanism 52 provided for the piston passage 47 closes the piston passage 47. On the other hand, the movement of the piston 9 causes the oil L to pass through the piston passage 50, open the damping force generating mechanism 53 provided for the piston passage 50, and flow from the second chamber 12, which is the other of the first chamber 11 and the second chamber 12, toward the first chamber 11, which is one of the first chamber 11 and the second chamber 12. In other words, the piston passage 50 allows the working fluid to flow out from the second chamber 12, which is the other of the first chamber 11 and the second chamber 12 in the cylinder 4, when the piston 9 moves in the other direction. The piston passage 50 constitutes a flow passage on the compression side through which the oil L flows out from the second chamber 12 during the compression stroke. The damping force generating mechanism 53 provided for the piston passage 50 is a damping force generating mechanism on the compression side that suppresses the flow of the oil L in the piston passage 50 on the compression side to generate a damping force.

[0030] A communication hole 55 is formed in the piston rod 8 at a position on the main shaft portion 41 side of the mounting shaft portion 40, penetrating the mounting shaft portion 40 in the radial direction. In addition, a communication hole 56 having a larger diameter than the communication hole 55 is formed in the piston rod 8 along the axial direction from the position of the communication hole 55 toward the opposite side to the main shaft portion 41. The communication hole 56 communicates with the communication hole 55 and opens at the tip of the mounting shaft portion 40 on the opposite side to the main shaft portion 41. These communication holes 55, 56 constitute a rod passage 57 provided in the piston rod 8. The rod passage 57 is a rod through passage penetrating inside the piston rod 8. The communication holes 55, 56 are formed in the piston rod 8 by a hole-making process using a drill.

[0031] The shock absorber 1 has a damping force variable mechanism 58 (device) attached to the piston 9 of the mounting shaft portion 40 of the piston rod 8 on the opposite side to the main shaft portion 41. The damping force variable mechanism 58 is attached so as to cover an opening located at the tip of the mounting shaft portion 40 of the communication hole 56 of the rod passage 57, and the inside of the damping force variable mechanism 58 communicates with the rod passage 57.

[0032] The shock absorber 1 described above is provided for each wheel of the vehicle. In this case, for example, one side of the shock absorber 1 is supported by the vehicle body, and the other side is fixed to the wheel side. Specifically, the shock absorber 1 is connected to the vehicle body side by the piston rod 8, and the mounting eye 25 shown in FIG. 1 on the opposite side to the protruding side of the piston rod 8 of the cylinder 4 is connected to the wheel side. Note that, in the case of a single-cylinder type, it is also possible to connect the cylinder 4 side to the vehicle body side and the piston rod 8 to the wheel side.

[0033] When the wheel vibrates as the vehicle travels, the relative positions of the cylinder 4 and the piston rod 8 change with the vibration, but the change is suppressed by the fluid resistance of the passage formed in the piston 9. As described below in detail, the fluid resistance of the passage formed in the piston 9 is designed to vary depending on the speed and amplitude of the vibration, and the ride comfort is improved by suppressing the vibration. In addition to the vibration generated by the wheel, inertial force and centrifugal force generated in the vehicle body as the vehicle travels also act between the cylinder 4 and the piston rod 8. For example, centrifugal force is generated in the vehicle body when the driving direction is changed by steering, and a force based on this centrifugal force acts between the cylinder 4 and the piston rod 8. As described below, the shock absorber 1 of this embodiment has good characteristics against vibration based on the force generated in the vehicle body as the vehicle travels, and high stability is obtained when the vehicle is traveling.

[0034] 2, the piston 9 has a substantially disk-shaped metal piston body 61 and a synthetic resin sliding member 62 attached to the outer circumferential surface of the piston body 61. The piston 9 comes into sliding contact with the inner circumferential surface of the inner tube 2 of the cylinder 4 at the sliding member 62. The piston body 61 is formed with an insertion hole 63 at the radial center so as to pass through in the axial direction, and the mounting shaft portion 40 of the piston rod 8 is fitted into this insertion hole 63. The piston passages 47, 50 described above are formed in the piston body 61 so as to surround the insertion hole 63.

[0035] An inner seat portion 71 and an outer seat portion 72 are formed at the axial end of the piston body 61 on the second chamber 12 side. The inner seat portion 71 has an annular shape and is provided between the annular groove 46 of the piston passage 47 and the insertion hole 63. The inner seat portion 71 has an end face on the second chamber 12 side in the axial direction of the piston body 61 that is flat and perpendicular to the insertion hole 63. The outer seat portion 72 has an annular shape and is provided so as to surround, from the radial outside, the annular groove 46 of the piston passage 47. The outer seat portion 72 constitutes the damping force generating mechanism 52. The piston passage 50 opens to the radial outside of the outer seat portion 72.

[0036] An inner seat portion 75 and an outer seat portion 76 are formed at the axial end of the piston body 61 on the first chamber 11 side. The inner seat portion 75 has a circular ring shape and is provided between the annular groove 49 of the piston passage 50 and the insertion hole 63. The inner seat portion 75 has an end face on the first chamber 11 side in the axial direction of the piston body 61 that is flat and perpendicular to the insertion hole 63. The outer seat portion 76 has an annular shape and is provided so as to surround the annular groove 49 of the piston passage 50 from the radial outside. The outer seat portion 76 constitutes the damping force generating mechanism 53. The piston passage 47 opens to the radial outside of the outer seat portion 76.

[0037] The damping force generating mechanism 52 is composed of the outer seat portion 72 and an annular damping valve 81 having an outer diameter larger than that of the outer seat portion 72 and capable of being seated on the outer seat portion 72. The damping valve 81 is composed of a plurality of annular single-plate disks stacked one on top of the other. A small-diameter disk 82 having a smaller diameter than the outer seat portion 72 is disposed between the damping valve 81 and the inner seat portion 71 of the piston body 61. The damping force generating mechanism 52 closes the piston passage 47 by the damping valve 81 abutting against the outer seat portion 72. Also, the damping force generating mechanism 52 opens the piston passage 47 by the damping valve 81 moving away from the outer seat portion 72. At that time, the damping valve 81 generates a damping force. In this manner, the damping force generating mechanism 52 opens and closes the piston passage 47 by the damping valve 81.

[0038] The damping force generating mechanism 52 has a fixed orifice (not shown) between the outer seat portion 72 and the damping valve 81, which communicates the piston passage 47 with the second chamber 12 even when these are in contact with each other. The fixed orifice (not shown) is formed by at least one of a groove formed in the outer seat portion 72 and an opening formed in the damping valve 81.

[0039] The damping force generating mechanism 52 is provided in the piston passage 47, and suppresses the flow of the oil L that occurs in the piston passage 47 when the piston 9 slides toward the first chamber 11, thereby generating a damping force.

[0040] The damping force generating mechanism 53 is composed of the outer seat portion 76 and an annular damping valve 91 having an outer diameter larger than that of the outer seat portion 76 and capable of being seated on the outer seat portion 76. The damping valve 91 is composed of a plurality of annular single-plate disks stacked one on top of the other. A small-diameter disk 92 having a diameter smaller than that of the outer seat portion 76 is disposed between the damping valve 91 and the inner seat portion 75 of the piston body 61. The damping force generating mechanism 53 closes the piston passage 50 by the damping valve 91 abutting against the outer seat portion 76. Also, the damping force generating mechanism 53 opens the piston passage 50 by the damping valve 91 moving away from the outer seat portion 76. At that time, the damping valve 91 generates a damping force. In this manner, the damping force generating mechanism 53 opens and closes the piston passage 50 by the damping valve 91.

[0041] The damping force generating mechanism 53 has a fixed orifice (not shown) between the outer seat portion 76 and the damping valve 91, which communicates the piston passage 50 with the first chamber 11 even when these are in contact with each other. The fixed orifice (not shown) is formed by at least one of a groove formed in the outer seat portion 76 and an opening formed in the damping valve 91.

[0042] The damping force generating mechanism 53 is provided in the piston passage 50, and generates a damping force by suppressing the flow of oil L that occurs in the piston passage 50 when the piston 9 slides toward the second chamber 12.

[0043] The mounting shaft portion 40 of the piston rod 8 has a threaded shaft portion 96 with a male thread 95 formed on its outer periphery on the axial side opposite to the main shaft portion 41. The mounting shaft portion 40 has a fitting shaft portion 97 with a cylindrical outer periphery 97a perpendicular to the end face 41a of the main shaft portion 41 between the main shaft portion 41 and the threaded shaft portion 96 in the axial direction. The communication hole 55 constituting the rod passage 57 opens to the outer periphery 97a of the fitting shaft portion 97 on the main shaft portion 41 side.

[0044] The shock absorber 1 has, arranged on the mounting shaft portion 40 of the piston rod 8 in the axial direction from the main shaft portion 41 side, a washer 101, an introduction member 102, a notched disk 103 (notched member), a retainer 104, a small diameter disk 105, the damping valve 91 consisting of the above-mentioned multiple single-plate disks, the above-mentioned small diameter disk 92, the above-mentioned piston 9, the above-mentioned small diameter disk 82, the damping valve 81 consisting of the above-mentioned multiple single-plate disks, a small diameter disk 106, a large diameter disk 107 and a washer 108.

[0045] The washers 101, 108, the introduction member 102, the notched disk 103, the retainer 104, the damping valves 81, 91, the small diameter disks 82, 92, 105, 106, the piston 9, and the large diameter disk 107 are all annular, and are provided with the mounting shaft portion 40 fitted inside. As a result, the washers 101, 108, the introduction member 102, the notched disk 103, the retainer 104, the damping valves 81, 91, the small diameter disks 82, 92, 105, 106, the piston 9, and the large diameter disk 107 are all coaxially disposed with respect to the piston rod 8, and positioned in the radial direction.

[0046] The washer 101 abuts against the end surface 41a of the main shaft portion 41 on the mounting shaft portion 40 side. The washers 101, 108, the introduction member 102, the notched disk 103, the retainer 104, the damping valves 81, 91, the small diameter disks 82, 92, 105, 106, the piston 9 and the large diameter disk 107 are all fitted into the fitting shaft portion 97. The washer 108 is fitted into the fitting shaft portion 97 on the large diameter disk 107 side in the axial direction, and the threaded shaft portion 96 is disposed on the inside on the side opposite the large diameter disk 107 in the axial direction.

[0047] The notched disc 103, the retainer 104, the single discs constituting the damping valves 81, 91, the small diameter discs 82, 92, 105, 106 and the large diameter disc 107 are all made of metal and are formed by press molding from a flat thin plate of a constant thickness.

[0048] The washers 101, 108 and the introduction member 102 are all made of metal. The washers 101, 108 and the introduction member 102 are thicker and more rigid than the notched disk 103, the retainer 104, the single-plate disks constituting the damping valves 81, 91, the small diameter disks 82, 92, 105, 106 and the large diameter disk 107.

[0049] The washer 101 is formed, for example, by machining. One axial end face of the washer 101 is flat, and the other axial end face is flat and extends parallel to the one axial end face. The inner peripheral surface of the washer 101 is cylindrical and perpendicular to both end faces, and the outer peripheral surface is cylindrical and coaxial with the inner peripheral surface.

[0050] The outer diameter of washer 101, that is, the outer diameter of the outer circumferential surface, is larger than the outer diameter of end surface 41a of main shaft portion 41. The fitting shaft portion 97 of the piston rod 8 is fitted at its outer peripheral surface 97a to the inner peripheral surface of the washer 101. One axial end face of the washer 101 is in surface contact with the end face 41a of the main shaft portion 41 of the piston rod 8.

[0051] The introduction member 102 is formed by, for example, sintering. As shown in Fig. 3, the introduction member 102 has an end face 102a on one axial side which is flat, and an end face 102b on the other axial side which is flat and extends parallel to the end face 102a.

[0052] The introduction member 102 has, on its radially inner side, a small-diameter inner circumferential surface 102c, a tapered inner circumferential surface 102d, and a large-diameter inner circumferential surface 102e. The small-diameter inner peripheral surface 102c has a cylindrical surface shape perpendicular to the end face 102a, and is formed on the end face 102a side of the introduction member 102 in the axial direction. The large-diameter inner peripheral surface 102e is a cylindrical surface having an inner diameter larger than that of the small-diameter inner peripheral surface 102c, and is formed on the end surface 102b side of the introduction member 102 in the axial direction. The tapered inner peripheral surface 102d is tapered and connects an axial end edge of the small diameter inner peripheral surface 102c on the side of the large diameter inner peripheral surface 102e to an axial end edge of the large diameter inner peripheral surface 102e on the side of the small diameter inner peripheral surface 102c. The tapered inner peripheral surface 102d is tapered such that the inner diameter becomes larger as it approaches the large diameter inner peripheral surface 102e. The small diameter inner peripheral surface 102c, the tapered inner peripheral surface 102d, and the large diameter inner peripheral surface 102e are coaxially arranged. The outer peripheral surface 102f of the introduction member 102 is a cylindrical surface that is coaxial with the small-diameter inner peripheral surface 102c, the tapered inner peripheral surface 102d, and the large-diameter inner peripheral surface 102e.

[0053] Therefore, the radially inner side of the introduction member 102 has a countersunk shape having a small diameter inner circumferential surface 102c and a large diameter inner circumferential surface 102e that have different inner diameters. The inner diameter of the introduction member 102, i.e., the inner diameter of the small diameter inner surface 102c, is the same as the inner diameter of the inner surface of the washer 101, and the outer diameter of the introduction member 102, i.e., the outer diameter of the outer surface 102f, is slightly smaller than the outer diameter of the outer surface of the washer 101.

[0054] The fitting shaft portion 97 of the piston rod 8 is fitted at its outer circumferential surface 97a into the small diameter inner circumferential surface 102c of the introduction member 102. The end face 102a of the introduction member 102 is in surface contact with the end face of the washer 101 opposite to the main shaft portion 41. The large diameter inner circumferential surface 102e and the tapered inner circumferential surface 102d of the introduction member 102 form a gap 110 between the outer circumferential surface 97a of the fitting shaft portion 97 and the large diameter inner circumferential surface 102e and the tapered inner circumferential surface 102d. The gap 110 is annular.

[0055] The large-diameter inner peripheral surface 102e and the tapered inner peripheral surface 102d of the introduction member 102 overlap with the communicating hole 55 of the piston rod 8 in the axial direction of the piston rod 8. Thus, a gap 110 between the large-diameter inner peripheral surface 102e and the tapered inner peripheral surface 102d of the introduction member 102 and the outer peripheral surface 97a of the fitting shaft portion 97 communicates with the rod passage 57. The small-diameter inner peripheral surface 102c of the introduction member 102 is disposed closer to the main shaft portion 41 than the communicating hole 55 of the piston rod 8 in the axial direction of the piston rod 8.

[0056] The notched disk 103 has a flat end face 103a on one axial side, and a flat end face 103b on the other axial side that extends parallel to the end face 103a. 4, the notched disk 103 has, on its radially inner side, an inner circumferential surface 103c that is a cylindrical surface that is interrupted in the circumferential direction perpendicular to the end surface 103a, and notches 121 that extend from the broken portion of the inner circumferential surface 103c radially outward to a radially intermediate position of the notched disk 103. The notched disk 103 has multiple, specifically six, notches 121 of the same shape formed at equal intervals in the circumferential direction.

[0057] The cutout portion 121 axially penetrates the cutout disk 103. The cutout portion 121 has a narrow portion 122 formed on the radially inner side of the cutout disk 103, and a wide portion 123 formed on the radially outer side of the cutout disk 103, the wide portion 123 being wider in the circumferential direction of the cutout disk 103 than the narrow portion 122.

[0058] 3, the diameter of the notched portion 121 in the radial direction of the notched disk 103 is larger than the diameter of the large-diameter inner circumferential surface 102e of the introduction member 102. In other words, the radius of the large-diameter inner circumferential surface 102e of the introduction member 102 is smaller than the distance from the center of the notched disk 103 to the outer end of the notched portion 121 in the radial direction of the notched disk 103. The outer peripheral surface 103d of the notched disk 103 is a cylindrical surface coaxial with the inner peripheral surface 103c.

[0059] The inner diameter of the notched disk 103, i.e., the inner diameter of the inner peripheral surface 103c, is the same as the inner diameter of the small-diameter inner peripheral surface 102c of the introduction member 102, and the outer diameter of the notched disk 103, i.e., the outer diameter of the outer peripheral surface 103d, is the same as the outer diameter of the outer peripheral surface 102f of the introduction member 102. The inner diameter of the notched disk 103, i.e., the inner diameter of the inner peripheral surface 103c, is smaller than the inner diameter of the large-diameter inner peripheral surface 102e of the introduction member 102.

[0060] The fitting shaft portion 97 of the piston rod 8 is fitted at its outer peripheral surface 97a into the inner peripheral surface 103c of the notched disk 103. The end surface 103a of the notched disk 103 is in surface contact with the end surface 102b of the introduction member 102. Then, the passages in the multiple notches 121 of the notched disk 103 communicate with the gap 110 between the introduction member 102 and the fitting shaft portion 97 at the radially inner portion of the notched disk 103.

[0061] The retainer 104 has a flat end face 104a on one axial side and a flat end face 104b on the other axial side that extends parallel to the end face 104a. The retainer 104 has an inner peripheral surface 104c that is cylindrical and perpendicular to the end faces 104a and 104b, and an outer peripheral surface 104d that is cylindrical and coaxial with the inner peripheral surface 104c.

[0062] The inner diameter of the retainer 104, i.e., the inner diameter of the inner peripheral surface 104c, is the same as the inner diameter of the inner peripheral surface 103c of the notched disk 103, and the outer diameter of the retainer 104, i.e., the outer diameter of the outer peripheral surface 104d, is smaller than the outer diameter of the outer peripheral surface 103d of the notched disk 103.

[0063] At least a portion of the retainer 104 has a smaller diameter than the diameter of the notched portion 121 in the radial direction of the notched disk 103. Specifically, the entire outer circumferential surface 104d of the retainer 104 has a smaller diameter than the diameter of the notched portion 121 in the radial direction of the notched disk 103. In other words, the distance from the center of the retainer 104 to the outer circumferential surface 104d, i.e., the radius, is smaller than the distance from the center of the notched disk 103 to the outer end of the notched portion 121 in the radial direction of the notched disk 103.

[0064] The fitting shaft portion 97 of the piston rod 8 is fitted at its outer peripheral surface 97a into the inner peripheral surface 104c of the retainer 104. The end face 104a of the retainer 104 is in surface contact with the end face 103b of the notched disk 103. Then, the passages in the multiple cutouts 121 of the notched disk 103 communicate with the first chamber 11 at a portion of the notched disk 103 that is radially outward of the retainer 104. A retainer 104 supports the notched disk 103 relative to the introduction member 102 .

[0065] A gap 110 between the introduction member 102 and the fitting shaft portion 97 and the passages in the multiple cutouts 121 form an orifice 111 that communicates between the rod passage 57 and the first chamber 11. Of the passages in the multiple cutouts 121, the orifice 111 has a flow path area that is narrowest at a portion sandwiched between an end face 102b of the introduction member 102 and an end face 104a of the retainer 104.

[0066] The introduction member 102, the notched disk 103, and the retainer 104 constitute an orifice mechanism 112 that forms an orifice 111 that communicates between the rod passage 57 and the first chamber 11. In other words, the orifice mechanism 112 includes the introduction member 102, through which the mounting shaft portion 40 of the piston rod 8 is inserted and which has a gap 110 on the inner circumferential side that communicates with the rod passage 57, the notched disk 103, through which the mounting shaft portion 40 of the piston rod 8 is inserted and which has a notched portion 121 that guides the oil liquid L as the working fluid from the first chamber 11 to the gap 110, and the retainer 104, through which the mounting shaft portion 40 of the piston rod 8 is inserted and which abuts against the notched disk 103, supports the notched disk 103 relative to the introduction member 102, and has at least a portion having a smaller diameter than the notched portion 121. As shown in FIG. 2, the orifice mechanism 112 has an orifice 111 that guides oil L as a working fluid from the first chamber 11 to the rod passage 57, i.e., the variable damping force mechanism 58, and also guides oil L from the rod passage 57, i.e., the variable damping force mechanism 58, to the first chamber 11.

[0067] 3, the small diameter disk 105 has a flat end face on one axial side and a flat end face on the other axial side extending parallel to the end face on the one axial side. The small diameter disk 105 has an inner peripheral surface that is cylindrical and perpendicular to the end faces on both axial sides, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0068] The small diameter disc 105 has an inner diameter equal to the inner diameter of the retainer 104, and an outer diameter slightly larger than the outer diameter of the retainer 104 and equal to the outer diameter of the inner seat portion 75 of the piston 9. The small diameter disc 105 has an outer peripheral surface smaller than the diameter of the notched portion 121 in the radial direction of the notched disc 103 all around. In other words, the radius of the small diameter disc 105 is smaller than the distance from the center of the notched disc 103 to the outer end of the notched portion 121 in the radial direction of the notched disc 103.

[0069] The fitting shaft portion 97 of the piston rod 8 is fitted at an outer peripheral surface 97a into the inner peripheral surface of the small diameter disc 105. The small diameter disc 105 has an end face on one axial side in surface contact with an end face 104b of the retainer 104.

[0070] The damping valve 91 has a flat end face on one axial side, i.e., on one side in the stacking direction of the single-plate discs, and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The damping valve 91 has an inner circumferential surface that is cylindrical and perpendicular to the end faces on both axial sides, and an outer circumferential surface that is cylindrical and arranged coaxially with the inner circumferential surface.

[0071] The damping valve 91 has an inner diameter equal to the inner diameter of the small diameter disk 105 and an outer diameter larger than the outer diameter of the washer 101 . An outer circumferential surface 97a of a fitting shaft portion 97 of the piston rod 8 fits into an inner circumferential surface of the damping valve 91. One axial end face of the damping valve 91 comes into surface contact with an end face of the small diameter disc 105 opposite the retainer 104.

[0072] The small diameter disk 92 has a flat end face on one axial side and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The small diameter disk 92 has an inner peripheral surface that is cylindrical and perpendicular to the end faces on both axial sides, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0073] The small diameter disk 92 has an inner diameter equal to the inner diameter of the damping valve 91 and an outer diameter smaller than the outer diameter of the damping valve 91 . The fitting shaft portion 97 of the piston rod 8 is fitted at an outer peripheral surface 97a onto the inner peripheral surface of the small diameter disc 92. The small diameter disc 92 has one end face on one axial side in surface contact with an end face of the damping valve 91 opposite to the small diameter disc 105.

[0074] The fitting shaft portion 97 of the piston rod 8 is fitted at an outer peripheral surface 97a into the insertion hole 63 of the piston 9. The other axial end face of the small diameter disc 92 is in surface contact with the end face of the inner seat portion 75 of the piston 9.

[0075] As described above, the damping valve 91 is provided between the introduction member 102 of the orifice mechanism 112 and the piston 9. In the orifice mechanism 112, the notched disk 103 is provided on the damping valve 91 side of the introduction member 102. In the orifice mechanism 112, the retainer 104 is provided on the damping valve 91 side of the introduction member 102. In the orifice mechanism 112, the retainer 104 is provided on the damping valve 91 side of the notched disk 103.

[0076] 2, the small diameter disk 82 has a flat end face on one axial side and a flat end face on the other axial side extending parallel to the end face on the one axial side. The small diameter disk 82 has an inner peripheral surface that is cylindrical and perpendicular to the end faces on both axial sides, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0077] The small diameter disk 82 has an inner diameter equal to the inner diameter of the damping valve 91 and an outer diameter smaller than the outer diameter of the damping valve 91 . The fitting shaft portion 97 of the piston rod 8 is fitted at an outer peripheral surface 97a onto the inner peripheral surface of the small diameter disc 82. One end face of the small diameter disc 82 in the axial direction is in surface contact with an end face of the inner seat portion 71 of the piston 9.

[0078] The damping valve 81 has a flat end face on one axial side, i.e., on one side in the stacking direction of the single-plate discs, and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The damping valve 81 has an inner circumferential surface that is cylindrical and perpendicular to the end faces on both axial sides, and an outer circumferential surface that is cylindrical and arranged coaxially with the inner circumferential surface.

[0079] The damping valve 81 has an inner diameter equal to the inner diameter of the small diameter disk 82 , and an outer diameter larger than the outer diameter of the small diameter disk 82 and equal to the outer diameter of the damping valve 91 . An outer peripheral surface 97a of a fitting shaft portion 97 of the piston rod 8 fits into an inner peripheral surface of the damping valve 81. One axial end face of the damping valve 81 comes into surface contact with an end face of the small diameter disc 82 opposite to the piston 9.

[0080] The small diameter disk 106 has a flat end face on one axial side and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The small diameter disk 106 has an inner peripheral surface that is cylindrical and perpendicular to the end faces on both axial sides, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0081] The small diameter disk 106 has an inner diameter equal to the inner diameter of the damping valve 81 and an outer diameter smaller than the outer diameter of the damping valve 81 . The fitting shaft portion 97 of the piston rod 8 is fitted at an outer peripheral surface 97a onto the inner peripheral surface of the small diameter disc 106. The small diameter disc 106 has one end face on one axial side in surface contact with an end face of the damping valve 81 opposite to the small diameter disc 82.

[0082] The large diameter disk 107 has a flat end face on one axial side and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The large diameter disk 107 has an inner peripheral surface that is cylindrical and perpendicular to the end faces on both axial sides, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0083] The large diameter disc 107 has an inner diameter equal to that of the small diameter disc 106, and an outer diameter larger than that of the small diameter disc 106 and equal to that of the damping valve 81. The fitting shaft portion 97 of the piston rod 8 fits into the inner peripheral surface of the large diameter disc 107 at its outer peripheral surface 97a. One axial end face of the large diameter disc 107 comes into surface contact with the end face of the small diameter disc 106 opposite to the damping valve 81.

[0084] The washer 108 is formed, for example, by machining. One axial end face of the washer 108 is flat, and the other axial end face is flat and extends parallel to the end face. The inner peripheral surface of the washer 108 is cylindrical and perpendicular to both end faces, and the outer peripheral surface is cylindrical and coaxial with the inner peripheral surface.

[0085] The washer 108 has an inner diameter equal to that of the large diameter disc 107, and an outer diameter smaller than that of the large diameter disc 107 and larger than that of the small diameter disc 106. The fitting shaft portion 97 of the piston rod 8 fits into the inner peripheral surface of the washer 108 at its outer peripheral surface 97a. One axial end face of the washer 108 comes into surface contact with the end face of the large diameter disc 107 opposite to the small diameter disc 106.

[0086] The shock absorber 1 has a nut 131 provided on the mounting shaft portion 40 of the piston rod 8 on the axial side opposite to the large diameter disk 107 of the washer 108. The nut 131 is screwed onto the male thread 95 of the screw shaft portion 96 of the mounting shaft portion 40.

[0087] The nut 131 has a flat end face on one axial side and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The inner periphery of the nut 131 is a female screw 132 perpendicular to the end faces on both axial sides, and the outer periphery is hexagonal.

[0088] The nut 131 is screwed at the female thread 132 into the male thread 95 of the screw shaft portion 96. Then, one axial end face of the nut 131 comes into surface contact with an end face of the washer 108 opposite to the large diameter disk 107. When the nut 131 is tightened onto the screw shaft portion 96, it clamps the washer 101, the introduction member 102, the notched disk 103, the retainer 104, the small diameter disk 105, the damping valve 91, the small diameter disk 92, the piston 9, the small diameter disk 82, the damping valve 81, the small diameter disk 106, the large diameter disk 107, and the washer 108 between the nut 131 and the main shaft portion 41. As a result, the washers 101, 108, the introduction member 102, the notched disc 103, the retainer 104, the damping valves 81, 91, the small diameter discs 82, 92, 105, 106, the piston 9 and the large diameter disc 107 are fixed to the mounting shaft portion 40 of the piston rod 8.

[0089] The damping force variable mechanism 58 is composed of a housing 143 consisting of a cover member 141 and a housing main body 142, a free piston 145, an O-ring 147 which is a rubber member, and an O-ring 148 which is a rubber member.

[0090] The cover member 141 is formed with a female thread 151 that screws into the male thread 95 of the piston rod 8. The housing body 142 is substantially cylindrical, and one open end side of the housing body 142 is attached to the cover member 141. The free piston 145 is provided in the housing 143 so as to be movable in the axial direction. The O-ring 147 is provided between the free piston 145 and the cover member 141 of the housing 143, and serves as a contraction-side elastic body that is compressed and deformed when the free piston 145 moves axially toward the cover member 141 side relative to the housing 143. The O-ring 148 is provided between the free piston 145 and the housing body 142 of the housing 143, and serves as an extension-side elastic body that is compressed and deformed when the free piston 145 moves in the opposite direction relative to the housing 143. For convenience, the O-rings 147 and 148 are shown in their natural state in FIG. 2. In particular, the O-ring 148 also functions as a seal, so it is desirable to arrange it so that it is always deformed into a noncircular cross section when attached. The above-mentioned O-ring 147 is a resistance element that is compressed and deformed when the free piston 145 moves in one direction, generating a resistance force against the displacement of the free piston 145, and the O-ring 148 is a resistance element that is compressed and deformed when the free piston 145 moves in the other direction, generating a resistance force against the displacement of the free piston 145.

[0091] The lid member 141 is made of a metal such as iron and is formed mainly by cutting. The lid member 141 has a lid inner cylinder part 152, a lid base plate part 153, a lid outer cylinder part 154, and a fitting protrusion part 155. The lid inner cylinder part 152 is substantially cylindrical, and the above-mentioned female thread 151 is formed on its inner periphery. The lid base plate part 153 is a holed disk shape that spreads outward in the radial direction from one end part in the axial direction of the lid inner cylinder part 152. The lid outer cylinder part 154 extends from the outer periphery side of the lid base plate part 153 in the same direction as the lid inner cylinder part 152. The fitting protrusion part 155 is annular and protrudes outward in the radial direction from the same side of the lid outer cylinder part 154 as the lid base plate part 153 in the axial direction. The fitting protrusion 155 has a tapered surface portion 156 at its axial end on the lid outer cylinder portion 154 side, the tapered surface portion 156 gradually decreasing in diameter and connecting to the lid outer cylinder portion 154 .

[0092] The inner peripheral surface of the lid outer cylinder portion 154 has, in that order from the lid base plate portion 153 side, a cylindrical surface portion 158 and an inclined surface portion 159. The cylindrical surface portion 158 has a constant diameter. The inclined surface portion 159 is connected to the cylindrical surface portion 158 and has an annular shape whose diameter increases as it moves away from the cylindrical surface portion 158 in the axial direction. The cross section of the inclined surface portion 159 on a plane including the central axis of the lid member 141 has a substantially arc shape.

[0093] The housing body 142 is made of a metal such as iron and is formed mainly by cutting, and has a substantially cylindrical shape. An inner annular protrusion 161 is formed on one axial side of the housing body 142, protruding radially inward. On the inner peripheral surface of the housing body 142, a small diameter cylindrical surface portion 162, an inclined surface portion 163, a large diameter cylindrical surface portion 164, a tapered surface portion 165, and a fitting cylindrical surface portion 166 are formed in this order from the one axial side. The small diameter cylindrical surface portion 162 has a constant diameter. The inclined surface portion 163 is connected to the small diameter cylindrical surface portion 162, and is an annular shape whose diameter increases as it moves away from the small diameter cylindrical surface portion 162. The large diameter cylindrical surface portion 164 is connected to the inclined surface portion 163, and has a constant diameter larger than that of the small diameter cylindrical surface portion 162. The tapered surface portion 165 is connected to the large diameter cylindrical surface portion 164, and is tapered so that the diameter increases as it moves away from the large diameter cylindrical surface portion 164. The fitting cylindrical surface portion 166 is connected to the tapered surface portion 165, and has a constant diameter larger than the large diameter cylindrical surface portion 164. The inclined surface portion 163 has a cross section that is approximately arc-shaped on a plane that includes the central axis of the housing main body 142. The small diameter cylindrical surface portion 162 and the inclined surface portion 163 are formed on the inner annular protrusion 161. Although the housing main body 142 is described as being cylindrical, it is desirable for the inner peripheral surface to have a circular cross section, but the outer peripheral surface may have a non-circular cross section, such as a polygonal cross section.

[0094] In such a housing main body 142, the fitting convex portion 155 of the lid member 141 is inserted into the fitting cylindrical surface portion 166 with the fitting cylindrical surface portion 166 extending to an end portion opposite the inner annular protrusion 161 in the axial direction. Then, with the tapered surface portion 156 of the fitting convex portion 155 abutting against the tapered surface portion 165, the portion of the housing main body 142 opposite the inner annular protrusion 161 in the axial direction from the fitting convex portion 155 is bent radially inward, so that the housing main body 142 and the lid member 141 are integrated to form the housing 143. The lid outer cylinder portion 154 of the lid member 141 forms an annular small diameter portion that protrudes radially inward from the large diameter cylindrical surface portion 164 in the housing 143, and an inclined surface portion 159 is formed in this portion. Furthermore, the inner annular protrusion 161 of the housing body 142 constitutes an annular small diameter portion that protrudes radially inward from the large diameter cylindrical surface portion 164 in the housing 143, and an inclined surface portion 163 is formed in this portion. In the housing 143, the inclined surface portion 159 and the inclined surface portion 163 are disposed to face each other in the axial direction.

[0095] The free piston 145 is an integrally molded product made of a synthetic resin material such as polyacetal. The free piston 145 has a substantially cylindrical piston cylinder portion 171 and a curved plate-like piston bottom portion 172. The piston bottom portion 172 is formed so as to close one end side of the piston cylinder portion 171 in the axial direction. The piston cylinder portion 171 has an opening portion 173 on the opposite side of the piston bottom portion 172 in the axial direction. The free piston 145 has a bottomed cylindrical shape having the piston cylinder portion 171 and the piston bottom portion 172. The free piston 145 is made of only a resin material.

[0096] An outer annular protrusion 181 that protrudes radially outward from the outer periphery is formed at the middle position in the axial direction of the piston cylinder portion 171. The outer annular protrusion 181 has a larger diameter than the cylinder body portion 182 excluding the outer annular protrusion 181 of the piston cylinder portion 171 and forms a ring shape that protrudes radially outward. In other words, the free piston 145 has the outer annular protrusion 181 that protrudes from the outer periphery of the piston cylinder portion 171.

[0097] On the outer circumferential surface of the piston cylinder portion 171, in order from the side opposite to the axial opening 173, there are formed a tapered surface portion 191, a small diameter cylindrical surface portion 192, an inclined surface portion 193, a large diameter cylindrical surface portion 194, an inclined surface portion 195, a small diameter cylindrical surface portion 196, and a tapered surface portion 197. The tapered surface portion 191, the small diameter cylindrical surface portion 192, the small diameter cylindrical surface portion 196, and the tapered surface portion 197 are formed on the cylinder main body portion 182. The inclined surface portion 193, the large diameter cylindrical surface portion 194, and the inclined surface portion 195 are formed on the outer annular protruding portion 181.

[0098] The tapered surface portion 191 is tapered so that the diameter becomes smaller toward the opposite side of the small diameter cylindrical surface portion 192 in the axial direction. The small diameter cylindrical surface portion 192 is connected to the large diameter side of the tapered surface portion 191 and has a constant diameter. The inclined surface portion 193 is connected to the small diameter cylindrical surface portion 192 and has an annular shape whose diameter becomes larger as it moves away from the small diameter cylindrical surface portion 192 in the axial direction. The large diameter cylindrical surface portion 194 is connected to the large diameter side of the inclined surface portion 193 and has a constant diameter larger than that of the small diameter cylindrical surface portion 192. The cross section of the inclined surface portion 193 on a plane including the central axis of the free piston 145 is substantially arc-shaped.

[0099] The inclined surface portion 195 is connected to the large diameter cylindrical surface portion 194, and has a circular shape with a smaller diameter as it moves away from the large diameter cylindrical surface portion 194. The small diameter cylindrical surface portion 196 is connected to the small diameter side of the inclined surface portion 195. The small diameter cylindrical surface portion 196 has a constant diameter that is the same as the small diameter cylindrical surface portion 192. The tapered surface portion 197 is connected to the small diameter cylindrical surface portion 196, and has a tapered shape with a smaller diameter as it moves away from the small diameter cylindrical surface portion 196 in the axial direction. The cross section of the inclined surface portion 195 on a plane including the central axis of the free piston 145 is approximately arc-shaped. The outer annular protrusion portion 181 is symmetrical with respect to a plane passing through the center position in the axial direction.

[0100] The free piston 145 has a plurality of passage holes 201 formed at intervals in the circumferential direction of the free piston 145. The passage holes 201 are formed at the axial center of the outer annular protrusion 181, in other words, at the axial center of the large diameter cylindrical surface portion 194. The passage holes 201 radially penetrate the position of the outer annular protrusion 181 in the axial direction of the piston cylinder portion 171. The passage holes 201 are slightly narrowed so that the diameter becomes smaller toward the inside in the radial direction of the piston cylinder portion 171. Specifically, the passage holes 201 are formed at two positions 180 degrees apart in the circumferential direction of the free piston 145.

[0101] The piston bottom 172 is curved spherically so as to move away from the opening 173 in the axial direction toward the radial center. The piston bottom 172 has a bottom main body 211 that is connected to the cylinder main body 182 of the piston cylinder 171 and closes the inside of the cylinder main body 182, and a protrusion 212 that protrudes from the radial center of the bottom main body 211 to the side opposite the opening 173.

[0102] The piston bottom 172 has a bottom main body portion 211 that is curved spherically so that it is spaced apart from the opening 173 in the axial direction toward the center in the radial direction. That is, the bottom main body portion 211 has a bottom surface portion 231 that is on the opening 173 side and faces the opening 173 side and is recessed in a curved shape, and a bottom surface portion 232 that is on the opposite side to the opening 173 and faces the opposite side to the opening 173 and protrudes in a curved shape.

[0103] The free piston 145 is disposed in the housing 143 such that the piston bottom 172 is disposed on the inner annular protrusion 161 side in the axial direction. When the free piston 145 is disposed in the housing 143, the large diameter cylindrical surface portion 194 slides in the axial direction on the position of the large diameter cylindrical surface portion 164 of the housing main body 142. When the free piston 145 is disposed in the housing 143, the tapered surface portion 191 and the small diameter cylindrical surface portion 192 on one side move in the axial direction on the position of the small diameter cylindrical surface portion 162 of the housing main body 142. When the free piston 145 is disposed in the housing 143, the small diameter cylindrical surface portion 196 and the tapered surface portion 197 on the other side move in the axial direction on the position of the cylindrical surface portion 158 of the lid outer cylinder portion 154 of the lid member 141.

[0104] With the free piston 145 disposed in the housing 143, the inclined surface portion 163 of the housing body 142 and the inclined surface portion 193 of the free piston 145 overlap with each other in the radial direction. Therefore, the inclined surface portion 163 of the housing body 142 and the inclined surface portion 193 of the free piston 145 face each other in the moving direction of the free piston 145. In addition, the inclined surface portion 159 of the lid outer cylinder portion 154 of the lid member 141 and the inclined surface portion 195 of the free piston 145 overlap with each other in the radial direction. Therefore, the inclined surface portion 159 of the lid member 141 and the inclined surface portion 195 of the free piston 145 face each other in the moving direction of the free piston 145.

[0105] An O-ring 148 (in its natural state shown in FIG. 2) is disposed between the small-diameter cylindrical surface portion 192 and the inclined surface portion 193 of the free piston 145 and the inclined surface portion 163 and the large-diameter cylindrical surface portion 164 of the housing main body 142. In other words, the O-ring 148 is disposed between the outer annular protrusion portion 181 of the free piston 145 and the inner annular protrusion 161 of the housing 143. In further words, the free piston 145 has an outer annular protrusion portion 181 in which the O-ring 148, which is an elastic body, is provided between the outer annular protrusion portion 181 and the housing 143. When in its natural state, the O-ring 148 has a circular cross section including the central axis. When in its natural state, the O-ring 148 has an inner diameter smaller than the small-diameter cylindrical surface portion 192 of the free piston 145 and an outer diameter larger than the large-diameter cylindrical surface portion 164 of the housing main body 142. That is, the O-ring 148 is fitted to both the free piston 145 and the housing 143 with an interference therebetween in the radial direction thereof.

[0106] In addition, an O-ring 147 (in its natural state shown in FIG. 2) is disposed between the large-diameter cylindrical surface portion 164 and the inclined surface portion 159 of the housing 143 and the inclined surface portion 195 and the small-diameter cylindrical surface portion 196 of the free piston 145. In other words, the O-ring 147 is disposed between the outer annular protrusion portion 181 of the free piston 145 and the lid outer cylinder portion 154 of the housing 143. In further words, the free piston 145 has an outer annular protrusion portion 181 in which the O-ring 147, which is an elastic body, is provided between the housing 143. When in its natural state, the cross section of the O-ring 147 including the central axis is circular. When in its natural state, the O-ring 147 has an inner diameter smaller than the small-diameter cylindrical surface portion 196 of the free piston 145 and an outer diameter larger than the large-diameter cylindrical surface portion 164 of the housing 143. That is, the O-ring 147 is also fitted to both the free piston 145 and the housing 143 with an interference therebetween in the radial direction thereof.

[0107] Both O-rings 147, 148 are common parts of the same size, and bias the free piston 145 so as to hold it in a predetermined neutral position in the axial direction relative to the housing 143 within the housing 143. At the same time, the O-rings 147, 148 allow the free piston 145 to move in both axial directions relative to the housing 143 by elastically deforming.

[0108] In the free piston 145, the O-ring 147 comes into contact with the small diameter cylindrical surface portion 196 and the inclined surface portion 195. Of the small diameter cylindrical surface portion 196 and the inclined surface portion 195, the inclined surface portion 195 is inclined with respect to the moving direction of the free piston 145. In the housing 143, the O-ring 147 comes into contact with the large diameter cylindrical surface portion 164 and the inclined surface portion 159. Of the large diameter cylindrical surface portion 164 and the inclined surface portion 159, the inclined surface portion 159 is inclined with respect to the moving direction of the free piston 145.

[0109] In the free piston 145, the O-ring 148 comes into contact with the small diameter cylindrical surface portion 192 and the inclined surface portion 193. Of the small diameter cylindrical surface portion 192 and the inclined surface portion 193, the inclined surface portion 193 is inclined with respect to the moving direction of the free piston 145. In the housing 143, the O-ring 148 comes into contact with the large diameter cylindrical surface portion 164 and the inclined surface portion 163. Of the large diameter cylindrical surface portion 164 and the inclined surface portion 163, the inclined surface portion 163 is inclined with respect to the moving direction of the free piston 145.

[0110] In other words, an outer annular protrusion 181 is provided on the outer periphery of the free piston 145, and both axial faces of the outer annular protrusion 181 form an inclined surface portion 193 and an inclined surface portion 195. An inner annular protrusion 161 having an inclined surface portion 163 and a lid outer cylinder portion 154 having an inclined surface portion 159 are provided on both sides of the outer annular protrusion 181 on the inner periphery of the housing 143. Also, O-rings 148 and 147 are provided between the outer annular protrusion 181 and the inner annular protrusion 161 and between the outer annular protrusion 181 and the lid outer cylinder portion 154, respectively.

[0111] When assembling the damping force variable mechanism 58, for example, the O-ring 148 is inserted into the housing body 142 up to the position of the inclined surface portion 163. Then, the free piston 145 is fitted inside the housing body 142 and the O-ring 148. At that time, the large diameter cylindrical surface portion 194 of the free piston 145 is guided to the large diameter cylindrical surface portion 164 of the housing body 142, and then the tapered surface portion 191 is inserted from the small diameter side into the O-ring 148 and the small diameter cylindrical surface portion 162 of the housing body 142. Next, the O-ring 147 is inserted between the housing body 142 and the free piston 145 up to the position of the inclined surface portion 195. Then, the cover member 141 is inserted into the housing body 142, and the housing body 142 is swaged. The damping force variable mechanism 58 thus preassembled is attached by screwing the female thread 151 into the male thread 95 of the mounting shaft portion 40 of the piston rod 8. At that time, the cover base plate portion 153 of the housing 143 abuts against the nut 131. As a result, the damping force variable mechanism 58 is fixed to one side of the piston 9 on the mounting shaft portion 40 of the piston rod 8. The outer diameter of the damping force variable mechanism 58, i.e., the outer diameter of the housing 143, is set smaller than the inner diameter of the inner cylinder 2 to a degree that does not cause flow resistance.

[0112] In the damping force variable mechanism 58, the space between the housing 143, the free piston 145, and the O-rings 147, 148 forms a housing internal passage 241. The housing internal passage 241 communicates with a rod passage 57 of the piston rod 8. The rod passage 57 provided in the piston rod 8 guides the oil L, which serves as a working fluid and is guided from the first chamber 11 via the orifice 111, to the housing internal passage 241 of the damping force variable mechanism 58.

[0113] The orifice 111 of the orifice mechanism 112, the rod passage 57, and the housing internal passage 241 constitute a rod side passage 242 that communicates with one of the first chambers 11 and the second chambers 12. The rod side passage 242 has the orifice 111. When the pressure of the first chamber 11 increases due to the movement of the piston 9 toward the first chamber 11, the oil L flows out of the first chamber 11 through the rod side passage 242. That is, the oil L flows out of the first chamber 11 to the rod side passage 242 due to the movement of the piston 9 toward the first chamber 11. The communication holes 55 and 56 formed in the piston rod 8 form at least a part of the flow path of the rod side passage 242 and communicate with at least one of the first chambers 11 and the second chambers 12. The housing internal passage 241 formed in the housing 143 has at least a part of the flow path of the rod side passage 242 inside.

[0114] The housing inner passage 241 is defined by the O-ring 148, the free piston 145, and the housing 143 into a first chamber side passage portion 243 that communicates with the first chamber 11 on the piston rod 8 side, and a second chamber side passage portion 244 that communicates with the second chamber 12 on the bottom side.

[0115] When the piston 9 moves toward the first chamber 11 during the extension stroke, the oil L in the first chamber 11, which is at a high pressure among the first chamber 11 and the second chamber 12, flows through the orifice 111 of the orifice mechanism 112 in the rod-side passage 242, the rod passage 57, and the first-chamber-side passage portion 243. Then, the free piston 145 moves toward the opposite side of the lid member 141 in the axial direction relative to the housing 143 while discharging the oil L in the second-chamber-side passage portion 244 into the second chamber 12. At that time, one O-ring 148 provided between the free piston 145 and the housing 143 abuts against the inclined surface portion 193 of the outer annular protrusion portion 181 located between the O-rings 147, 148 on the outer periphery of the free piston 145 and the inclined surface portion 163 of the inner annular protrusion 161 on the inner periphery of the housing 143, and is sandwiched between them and elastically deformed. That is, the one O-ring 148 generates an elastic force against the movement of the free piston 145 in one direction during the extension stroke.

[0116] When the piston 9 moves toward the second chamber 12 during the compression stroke, the oil L in the second chamber 12, which is the one having a high pressure among the first chamber 11 and the second chamber 12, presses the free piston 145. Then, the free piston 145 moves toward the lid member 141 in the axial direction relative to the housing 143 while injecting the oil L into the second chamber side passage portion 244. At that time, the free piston 145 discharges the oil L in the first chamber side passage portion 243 into the first chamber 11 through the rod passage 57 and the orifice 111 of the orifice mechanism 112. At that time, the other O-ring 147 provided between the free piston 145 and the housing 143 abuts against the inclined surface portion 195 of the outer annular protrusion portion 181 on the outer periphery of the free piston 145 and the inclined surface portion 159 of the lid outer cylinder portion 154 on the inner periphery of the housing 143, and is sandwiched between them and elastically deformed. That is, the other O-ring 147 generates an elastic force against the movement of the free piston 145 in the other direction during the compression stroke.

[0117] When the free piston 145 moves, the O-ring 148, the free piston 145, and the housing 143 define a first chamber side passage portion 243 and a second chamber side passage portion 244. Thus, the free piston 145 defines the rod side passage 242 into the orifice 111, the rod passage 57, and the first chamber side passage portion 243 on the upstream side of the flow of the oil liquid L when the piston 9 moves in one direction during the extension stroke, and the second chamber side passage portion 244 on the downstream side. The free piston 145 defines the rod side passage 242 into the second chamber side passage portion 244 on the upstream side of the flow of the oil liquid L when the piston 9 moves in the other direction during the compression stroke, and the first chamber side passage portion 243, the rod passage 57, and the orifice 111 on the downstream side.

[0118] Next, the operation of the shock absorber 1 described above will be described.

[0119] First, a case will be described in which it is assumed that the rod side passage 242 and the damping force variable mechanism 58 are not provided in the shock absorber 1. During the extension stroke in which the piston rod 8 moves to the extension side, the oil L flows from the first chamber 11 to the second chamber 12 through the piston passage 47. When the piston speed is in the very low speed range, the oil L introduced from the first chamber 11 to the piston passage 47 basically flows to the second chamber 12 through a fixed orifice (not shown) that is always open and is formed between the outer seat portion 72 and the damping valve 81 that abuts against the outer seat portion 72, and at that time, a damping force with orifice characteristics (the damping force is approximately proportional to the square of the piston speed) is generated. Also, when the piston speed increases and reaches the low speed range, the oil L introduced from the first chamber 11 to the piston passage 47 basically flows to the second chamber 12 through between the damping valve 81 and the outer seat portion 72 while opening the damping valve 81. As a result, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) is generated.

[0120] During the compression stroke in which the piston rod 8 moves toward the compression side, the oil L flows from the second chamber 12 to the first chamber 11 through the piston passage 50. When the piston speed is in the very low speed range, the oil L introduced from the second chamber 12 to the piston passage 50 basically flows to the first chamber 11 through a fixed orifice (not shown) that is always open and is formed between the outer seat portion 76 and the damping valve 91 that abuts against the outer seat portion 76, and at that time, a damping force with orifice characteristics (the damping force is approximately proportional to the square of the piston speed) is generated. Also, when the piston speed increases and reaches the low speed range, the oil L introduced from the second chamber 12 to the piston passage 50 basically flows to the first chamber 11 through between the damping valve 91 and the outer seat portion 76 while opening the damping valve 91. As a result, a damping force with valve characteristics (the damping force is approximately proportional to the piston speed) is generated.

[0121] Here, when the piston speed is slow, that is, in the very low speed range (e.g. 0.05 m / s) the frequency is relatively high (e.g. 7 Hz or higher), vibrations are caused by small unevenness of the road surface, for example, and in such a situation it is preferable to lower the damping force. On the other hand, even when the piston speed is slow, the frequency is relatively low (e.g. 2 Hz or lower), vibrations are caused by wobbling caused by the roll of the vehicle body, and in such a situation it is preferable to increase the damping force.

[0122] Correspondingly, the damping force variable mechanism 58 varies the damping force according to the frequency even when the piston speed is similarly slow. That is, when the piston speed is slow and the frequency of the reciprocating motion of the piston 9 becomes high, the pressure in the first chamber 11 increases during the extension stroke, and the free piston 145 moves toward the second chamber 12 in the axial direction relative to the housing 143 against the biasing force of the O-ring 148 on the second chamber 12 side in the axial direction while introducing the oil L from the first chamber 11 into the first chamber side passage portion 243 of the housing inner passage 241 of the damping force variable mechanism 58 through the orifice 111 and the rod passage 57 of the rod side passage 242. In this way, the free piston 145 moves toward the second chamber 12 in the axial direction, introducing the oil L from the first chamber 11 into the housing inner passage 241, and the flow rate of the oil L introduced from the first chamber 11 into the piston passage 47 and flowing into the second chamber 12 through the damping force generating mechanism 52 is reduced. This reduces the damping force. At that time, the amount of oil L flowing into the damping force variable mechanism 58 is controlled by the throttling effect of the orifice 111.

[0123] In the subsequent compression stroke, the pressure in the second chamber 12 increases, and the free piston 145, which had been moving toward the second chamber 12 in the axial direction, moves toward the first chamber 11 in the axial direction relative to the housing 143 against the biasing force of the O-ring 147 on the first chamber 11 side while discharging the oil L from the first chamber side passage portion 243 of the in-housing passage 241 of the damping force variable mechanism 58 to the first chamber 11 through the rod passage 57 of the piston rod 8 and the orifice 111 of the rod side passage 242. In this way, the free piston 145 moves toward the first chamber 11 in the axial direction, thereby expanding the volume of the second chamber 12 and reducing the flow rate of the oil L introduced from the second chamber 12 into the piston passage 50, passing through the damping force generating mechanism 53, and flowing into the first chamber 11. As a result, the damping force decreases. At this time, the amount of oil L discharged from the damping force variable mechanism 58 is controlled by the throttling effect of the orifice 111.

[0124] In a region where the frequency of the piston 9 is high, the frequency of the movement of the free piston 145 also increases accordingly. As a result, during each of the above-mentioned expansion strokes, the oil L flows from the first chamber 11 to the first-chamber side passage portion 243 of the housing inner passage 241, and during each of the compression strokes, the volume of the second chamber 12 expands by an amount corresponding to the movement of the free piston 145, so that the damping force is maintained in a reduced state.

[0125] On the other hand, when the piston speed is slow and the frequency of the piston 9 is low, the frequency of the movement of the free piston 145 is accordingly low. For this reason, although the oil L flows from the first chamber 11 to the first-chamber-side passage portion 243 of the housing inner passage 241 at the beginning of the extension stroke, the free piston 145 thereafter compresses the O-ring 148 and stops on the second chamber 12 side in the axial direction with respect to the housing 143, and the oil L stops flowing from the first chamber 11 to the first-chamber-side passage portion 243 of the housing inner passage 241. Therefore, the flow rate of the oil L introduced from the first chamber 11 into the piston passage 47, passing through the damping force generating mechanism 52 and flowing into the second chamber 12 does not decrease, and the damping force increases.

[0126] Even in the subsequent compression stroke, the volume of the second chamber 12 will expand at the beginning due to the movement of the free piston 145 relative to the housing 143, but thereafter the free piston 145 compresses the O-ring 147 and stops on the axial side of the first chamber 11 relative to the housing 143, and no longer affects the volume of the second chamber 12. As a result, the flow rate of the oil L that is introduced from the second chamber 12 into the piston passage 50, passes through the damping force generating mechanism 53 and flows into the first chamber 11 does not decrease, and the damping force increases.

[0127] The shock absorber described in Patent Document 1 has a variable damping force mechanism that varies the damping force characteristics according to the vibration state. However, there is a demand for suppressing a decrease in productivity of shock absorbers.

[0128] In the shock absorber described in Patent Document 1, the working fluid is introduced from a chamber in the cylinder to the damping force variable mechanism through a piston passage provided in the piston, an internal disc passage as an orifice provided in the disc that contacts the piston, and a rod passage provided in the piston rod. When the internal disc passage is formed in the disc, a notch is formed in the disc. If a notch is formed in the disc that contacts the piston, it is necessary to design and manufacture it according to the size and shape of the piston, which reduces productivity. In addition, since the shock absorber described in Patent Document 1 has a disc having a notch between the piston and the damping valve, it also affects the specifications of the damping valve. For this reason, for example, there is a restriction on the setting of the plate thickness of each single plate disc of the damping valve, and there is also a problem that the degree of freedom in setting is small. In addition, since a disc having a notch is installed between the piston and the damping valve, it becomes unstable as a retainer that serves as a fulcrum for the deflection of the damping valve, and there is a possibility that the damping force cannot be stably output due to variations during manufacturing and changes over time. These problems are not limited to the variable damping force mechanism, but can occur in any structure in which the working fluid is introduced from a chamber in a cylinder to a device via a rod passage and an orifice provided in the piston rod. Here, examples of devices other than the variable damping force mechanism include an extremely low speed valve mechanism that generates a damping force with valve characteristics from an extremely low piston speed, and a damping valve mechanism that is provided in parallel with the damping valve provided in the piston and opens in the same stroke.

[0129] The shock absorber 1 of the first embodiment includes a rod passage 57 that introduces oil L as a working fluid to a damping force variable mechanism 58 that is a device provided in a piston rod 8, and an orifice mechanism 112 that introduces the oil L as a working fluid from the first chamber 11 to the rod passage 57. The orifice mechanism 112 of the shock absorber 1 includes an introduction member 102 having a gap 110 that communicates with the rod passage 57 on its inner circumferential side, a notched disk 103 having a notched portion 121 that introduces the oil L as a working fluid from the first chamber 11 to the gap 110, and a retainer 104 that supports the notched disk 103 relative to the introduction member 102 and has at least a portion having a smaller diameter than the notched portion 121.

[0130] In this manner, in the shock absorber 1, the notched disk 103 is provided between the introduction member 102 and the retainer 104. In other words, the notched disk 103 that forms the orifice 111 is provided at a position independent of the piston 9. Therefore, in the shock absorber 1, it is not necessary to design and manufacture the notched disk 103 in accordance with the size and shape of the piston 9. In other words, the shock absorber 1 is not dependent on the size and shape of the piston 9. Therefore, the shock absorber 1 can suppress a decrease in productivity.

[0131] Furthermore, in the shock absorber 1, the notched disk 103 is provided between the introduction member 102 and the retainer 104 and does not play the role of a valve opening fulcrum for the damping valve 91, so that there is less impact on the specifications of the damping valve 91. Therefore, the shock absorber 1 reduces restrictions on the plate thickness setting of each single plate disk of the damping valve 91, making it possible to increase the degree of freedom in setting.

[0132] Furthermore, since the shock absorber 1 has the notched disk 103 provided between the introduction member 102 and the retainer 104, a disk without a notched portion can be used for the small diameter disk 92 serving as a retainer which serves as a fulcrum on the piston 9 side of the deflection of the damping valve 91. Therefore, the shock absorber 1 can suppress the axial force of the small diameter disk 92 serving as a retainer which serves as a fulcrum on the piston 9 side of the deflection of the damping valve 91 from becoming unstable, and can suppress the damping force from becoming unstable due to manufacturing variations or changes over time.

[0133] The shock absorber 1 has a damping valve 91 that is provided between the introduction member 102 and the piston 9 and opens and closes the piston passage 50, and the retainer 104 is provided on the damping valve 91 side of the introduction member 102. Therefore, the notched disk 103 is provided on the damping valve 91 side of the introduction member 102, and the gap 110 of the introduction member 102 can be disposed on the piston 9 side in the axial direction of the piston rod 8. This makes it possible to shorten the length of the communication hole 56 that constitutes the rod passage 57 communicating with the gap 110 and extends in the axial direction of the piston rod 8. Therefore, the number of steps for machining the communication hole 56 can be reduced, and the tool life can be improved.

[0134] [Second embodiment] Next, the second embodiment will be described focusing on the differences from the first embodiment with reference to Fig. 5. The same parts as the first embodiment will be designated by the same names and symbols.

[0135] In the shock absorber 1A of the second embodiment, an orifice mechanism 112A which is partially different from the orifice mechanism 112 is provided instead of the orifice mechanism 112. The orifice mechanism 112A has a notched disk 103 similar to that of the first embodiment, a retainer 104 similar to that of the first embodiment, and an introduction member 102A that is partially different from the introduction member 102 of the first embodiment. The shock absorber 1A has a backup disk 251, an intermediate disk 252, and a small diameter disk 253.

[0136] The backup disk 251, the retainer 104, the notched disk 103, the introduction member 102A, the intermediate disk 252, and the small diameter disk 253 are fitted to the mounting shaft portion 40 of the piston rod 8 in this order from the washer 101 side. The backup disk 251, the introduction member 102A, the intermediate disk 252, and the small diameter disk 253 are all annular, and by fitting the mounting shaft portion 40 to their insides, they are arranged coaxially with the piston rod 8 and positioned in the radial direction.

[0137] The backup disk 251 is made of metal and is formed by press molding from a flat thin plate of a constant thickness. The backup disk 251 has a flat end face on one axial side and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The backup disk 251 has an inner peripheral surface that is cylindrical and perpendicular to both end faces, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0138] The backup disk 251 has an inner diameter equal to the inner diameter of the washer 101 and an outer diameter larger than the outer diameter of the washer 101 and the outer diameter of the notched disk 103.

[0139] The fitting shaft portion 97 of the piston rod 8 is fitted at its outer peripheral surface 97a into the inner peripheral surface of the backup disk 251. One axial end face of the backup disk 251 is in surface contact with an end face of the washer 101 opposite the axial main shaft portion 41. The other axial end face of the backup disk 251 is in surface contact with an end face 104a of one axial side of the retainer 104. The other axial end face of the retainer 104 is in surface contact with an end face 103a of one axial side of the notched disk 103.

[0140] The introduction member 102A is made of metal and is formed by, for example, sintering. The introduction member 102A has a main body portion 261 and a protruding portion 262. The main body portion 261 is annular. The protruding portion 262 is annular, and protrudes from the inner periphery of the main body portion 261 toward one axial direction of the main body portion 261 .

[0141] The introduction member 102A has an end surface 102Aa on one axial side which is flat and formed on a protruding portion 262. The introduction member 102A has an end face 102Ab on the other axial side, which is flat and extends in parallel to the end face 102Aa, and is formed on a main body portion 261.

[0142] The introduction member 102A has, on the radially inner side, a small-diameter inner circumferential surface 102Ac, a tapered inner circumferential surface 102Ad, and a large-diameter inner circumferential surface 102Ae.

[0143] The small-diameter inner peripheral surface 102Ac has a cylindrical surface shape perpendicular to the end face 102Ab, and is formed on the end face 102Ab side in the axial direction of the introduction member 102A. The large-diameter inner peripheral surface 102Ae is a cylindrical surface having an inner diameter larger than that of the small-diameter inner peripheral surface 102Ac, and is formed on the end surface 102Aa side of the introduction member 102A in the axial direction. The tapered inner circumferential surface 102Ad is tapered and connects an axial end edge of the small diameter inner circumferential surface 102Ac on the side of the large diameter inner circumferential surface 102Ae to an axial end edge of the large diameter inner circumferential surface 102Ae on the side of the small diameter inner circumferential surface 102Ac. The tapered inner circumferential surface 102Ad is tapered such that the inner diameter becomes larger as it approaches the large diameter inner circumferential surface 102Ae. The small diameter inner peripheral surface 102Ac, the tapered inner peripheral surface 102Ad, and the large diameter inner peripheral surface 102Ae are coaxially arranged.

[0144] The introduction member 102A has, on the radially outer side, a large diameter outer circumferential surface 102Af, an intermediate surface 102Ag, and a small diameter outer circumferential surface 102Ah.

[0145] The large diameter outer circumferential surface 102Af is a cylindrical surface perpendicular to the end face 102Ab, and is formed on the end face 102Ab side in the axial direction of the introduction member 102A. The small diameter outer circumferential surface 102Ah is a cylindrical surface having an outer diameter smaller than that of the large diameter outer circumferential surface 102Af, and is formed on the end face 102Aa side in the axial direction of the introduction member 102A. The intermediate surface 102Ag is a plane parallel to the end faces 102Aa, 102Ab, and connects the axial edge of the large diameter outer circumferential surface 102Af on the end face 102Aa side to the axial edge of the small diameter outer circumferential surface 102Ah on the end face 102Ab side. The large diameter outer peripheral surface 102Af and the small diameter outer peripheral surface 102Ah are disposed coaxially with the small diameter inner peripheral surface 102Ac, the tapered inner peripheral surface 102Ad, and the large diameter inner peripheral surface 102Ae.

[0146] Therefore, the radially inner side of the introduction member 102A has a countersunk shape having a small diameter inner circumferential surface 102Ac and a large diameter inner circumferential surface 102Ae that have different inner diameters. The inner diameter of the introduction member 102A, i.e., the inner diameter of the small diameter inner surface 102Ac, is the same as the inner diameter of the inner surface 103c of the notched disk 103, and the outer diameter of the introduction member 102A, i.e., the outer diameter of the large diameter outer surface 102Af of the main body portion 261, is slightly smaller than the outer diameter of the notched disk 103.

[0147] The introduction member 102A has an outer diameter of the protrusion 262, i.e., an outer diameter of the small diameter outer peripheral surface 102Ah, which is equal to the outer diameter of the retainer 104. Therefore, at least a part of the introduction member 102A has a smaller diameter than the diameter of the notch 121 in the radial direction of the notched disk 103. Specifically, the introduction member 102A has a small diameter of the small diameter outer peripheral surface 102Ah over the entire circumference thereof, which is smaller than the diameter of the notch 121 in the radial direction of the notched disk 103. In other words, the distance from the center of the introduction member 102A to the small diameter outer peripheral surface 102Ah, i.e., the radius, is smaller than the distance from the center of the notched disk 103 to the outer end of the notch 121 in the radial direction of the notched disk 103.

[0148] The fitting shaft portion 97 of the piston rod 8 is fitted at its outer circumferential surface 97a into the small diameter inner circumferential surface 102Ac of the introduction member 102A. The end face 102Aa of the introduction member 102A is in surface contact with the end face 103b of the notched disk 103. The large diameter inner circumferential surface 102Ae and the tapered inner circumferential surface 102Ad of the introduction member 102A form a gap 110A between the outer circumferential surface 97a of the fitting shaft portion 97 and the end face 102Aa of the introduction member 102A.

[0149] The large-diameter inner peripheral surface 102Ae and the tapered inner peripheral surface 102Ad of the introduction member 102A are positioned in the axial direction of the piston rod 8 so as to overlap with the communicating hole 55 of the piston rod 8. Thus, a gap 110A between the large-diameter inner peripheral surface 102Ae and the tapered inner peripheral surface 102Ad of the introduction member 102A and the outer peripheral surface 97a of the fitting shaft portion 97 communicates with the rod passage 57. The small-diameter inner peripheral surface 102Ac of the introduction member 102A is disposed on the opposite side of the communicating hole 55 of the piston rod 8 to the main shaft portion 41 in the axial direction of the piston rod 8.

[0150] Here, the end face 103b of the notched disk 103 is in surface contact with the end face 102Aa of the introduction member 102A. The passages in the multiple notches 121 of the notched disk 103 communicate with the gap 110A between the introduction member 102A and the fitting shaft portion 97 at a radially inner portion of the notched disk 103. Also, the passages in the multiple notches 121 of the notched disk 103 communicate with the first chamber 11 at a radially outer portion of the notched disk 103 that is outward of the protruding portion 262 of the introduction member 102A.

[0151] The end face 104b of the retainer 104 is in surface contact with the end face 103a of the notched disk 103. As described in the first embodiment, at least a part of the retainer 104 has a smaller diameter than the diameter of the notched portion 121 in the radial direction of the notched disk 103. Specifically, the outer peripheral surface 104d of the retainer 104 has a smaller diameter than the diameter of the notched portion 121 in the radial direction of the notched disk 103 over the entire circumference. In other words, the distance from the center of the retainer 104 to the outer peripheral surface 104d, i.e., the radius, is smaller than the distance from the center of the notched disk 103 to the outer end of the notched portion 121 in the radial direction of the notched disk 103. The passages in the multiple notched portions 121 of the notched disk 103 communicate with the first chamber 11 in the portion of the notched disk 103 that is outside the retainer 104 in the radial direction. A retainer 104 supports the notched disk 103 relative to the lead-in member 102A.

[0152] A gap 110A between the introduction member 102A and the fitting shaft portion 97 and the passages in the multiple cutouts 121 form an orifice 111A that communicates between the rod passage 57 and the first chamber 11. Of the passages in the multiple cutouts 121, the orifice 111A has a flow path area that is narrowest at a portion sandwiched between an end face 102Aa of the introduction member 102A and an end face 104b of the retainer 104.

[0153] The introduction member 102A, the notched disk 103, and the retainer 104 constitute an orifice mechanism 112A that forms an orifice 111A that communicates between the rod passage 57 and the first chamber 11. In other words, the orifice mechanism 112A includes the introduction member 102A through which the mounting shaft portion 40 of the piston rod 8 is inserted and which has a gap 110A on the inner circumferential side that communicates with the rod passage 57, the notched disk 103 through which the mounting shaft portion 40 of the piston rod 8 is inserted and which has a notched portion 121 that guides the oil liquid L as the working fluid from the first chamber 11 to the gap 110A, and the retainer 104 through which the mounting shaft portion 40 of the piston rod 8 is inserted and which abuts against the notched disk 103, which supports the notched disk 103 relative to the introduction member 102A, and which has at least a portion having a smaller diameter than the notched portion 121. The orifice mechanism 112A has an orifice 111A that guides oil L as a working fluid from the first chamber 11 to the rod passage 57, i.e., the variable damping force mechanism 58 (see Figure 2), and also guides oil L from the rod passage 57, i.e., the variable damping force mechanism 58 (see Figure 2), to the first chamber 11.

[0154] The intermediate disk 252 is made of metal and is formed by press molding from a flat thin plate of a constant thickness. The intermediate disk 252 has a flat end face on one axial side and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The intermediate disk 252 has an inner peripheral surface that is cylindrical and perpendicular to both end faces, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0155] The inner diameter of the intermediate disk 252 is the same as the inner diameter of the small-diameter inner circumferential surface 102Ac of the introduction member 102A, and the outer diameter of the intermediate disk 252 is larger than the outer diameter of the introduction member 102A. The fitting shaft portion 97 of the piston rod 8 is fitted at an outer peripheral surface 97a into the inner peripheral surface of the intermediate disc 252. One axial end face of the intermediate disc 252 is in surface contact with an end face 102Ab of the introduction member 102A.

[0156] The small diameter disk 253 is made of metal and is formed by press molding from a flat thin plate of a constant thickness. The small diameter disk 253 has a flat end face on one axial side and a flat end face on the other axial side that extends parallel to the end face on the one axial side. The small diameter disk 253 has an inner peripheral surface that is cylindrical and perpendicular to both end faces, and an outer peripheral surface that is cylindrical and coaxial with the inner peripheral surface.

[0157] The small diameter disk 253 has an inner diameter equal to that of the intermediate disk 252 , and an outer diameter, i.e., the outer diameter of the outer peripheral surface, which is smaller than that of the intermediate disk 252 and equal to the outer diameter of the small diameter disk 105 . The fitting shaft portion 97 of the piston rod 8 is fitted at its outer peripheral surface 97a into the inner peripheral surface of the small diameter disk 253. One axial end face of the small diameter disk 253 is in surface contact with the end face of the intermediate disk 252 opposite the introduction member 102A. The other axial end face of the small diameter disk 253 is in surface contact with the end face of one axial end face of the small diameter disk 105.

[0158] The damping valve 91 is provided between the introduction member 102A of the orifice mechanism 112A and the piston 9. In the orifice mechanism 112A, a notched disk 103 is provided on the side of the introduction member 102A opposite to the damping valve 91. In the orifice mechanism 112A, a retainer 104 is provided on the side of the introduction member 102A opposite to the damping valve 91. In the orifice mechanism 112A, the retainer 104 is provided on the side of the notched disk 103 opposite to the damping valve 91.

[0159] The shock absorber 1A of the second embodiment operates in the same manner as the shock absorber 1 of the first embodiment, except that the oil L flows between the first chamber 11 and the rod passage 57 via an orifice 111A provided in place of the orifice 111.

[0160] The shock absorber 1A of the second embodiment includes a rod passage 57 that introduces oil L as a working fluid to a damping force variable mechanism 58 (see FIG. 2) that is a device provided in the piston rod 8, and an orifice mechanism 112A that introduces the oil L as a working fluid from the first chamber 11 to the rod passage 57. The orifice mechanism 112A of the shock absorber 1A includes an introduction member 102A having a gap 110A that communicates with the rod passage 57 on its inner circumferential side, a notched disk 103 having a notched portion 121 that introduces the oil L as a working fluid from the first chamber 11 to the gap 110A, and a retainer 104 that supports the notched disk 103 relative to the introduction member 102A and has at least a portion having a smaller diameter than the notched portion 121.

[0161] Therefore, since the shock absorber 1A has the notched disk 103 provided between the introduction member 102A and the retainer 104, it has the same effects as the shock absorber 1 of the first embodiment.

[0162] Furthermore, the shock absorber 1A has a damping valve 91 that is provided between the introduction member 102A and the piston 9 and opens and closes the piston passage 50, and the retainer 104 is provided on the opposite side of the introduction member 102A to the damping valve 91. As a result, in the shock absorber 1A, the notched disk 103 is provided on the opposite side of the introduction member 102A to the damping valve 91, and therefore the notched disk 103 can be separated from the damping valve 91. Therefore, the shock absorber 1A can be made less susceptible to the influence of the opening and closing of the damping valve 91 of the orifice 111A.

[0163] In addition, in the shock absorber 1A, the introduction member 102A has its large-diameter inner surface 102Ae facing away from the damping valve 91, and by using a backup disk 251 with a sufficiently large outer diameter, the stability of the fastening axial force and surface pressure of the damping valve 91 can be increased, thereby improving performance quality.

[0164] In addition, in the shock absorber 1A, the outer diameter of the retainer 104 that abuts against the notched disk 103 is made equal to or greater than the outer diameter of the small diameter disk 253 that is the retainer of the damping valve 91, thereby ensuring a fastening surface, and by placing a backup disk 251 with a sufficiently large outer diameter between the retainer 104 and the washer 101, stable fastening axial force and surface pressure can be ensured.

[0165] In addition, since the radial width, i.e., seat width, of the end face 102Aa of the shock absorber 1A that abuts against the notched disk 103 of the introduction member 102A is narrow, the degree of variation in the flow path area of ​​the notched portion 121 of the notched disk 103 due to the surface roughness of the end face 102A can be reduced.

[0166] [Third embodiment] Next, the third embodiment will be described with a focus on differences from the first embodiment, mainly with reference to Figures 6 to 9. Note that parts common to the first embodiment will be designated by the same names and reference numerals.

[0167] In the shock absorber 1B of the third embodiment, an orifice mechanism 112B which is partially different from the orifice mechanism 112 is provided instead of the orifice mechanism 112. The orifice mechanism 112B has an introduction member 102 similar to that of the first embodiment, a retainer 104 similar to that of the first embodiment, a notched disk 103B (notched member) partially different from the notched disk 103 of the first embodiment, and a backup disk 271.

[0168] In the orifice mechanism 112B, in order from the washer 101 side, the introduction member 102, the backup disk 271, the notched disk 103B, and the retainer 104 are fitted to the mounting shaft portion 40 of the piston rod 8. The backup disk 271 and the notched disk 103B are both annular, and by fitting the mounting shaft portion 40 to their insides, they are arranged coaxially with the piston rod 8 and positioned in the radial direction.

[0169] The backup disk 271 is made of metal and is formed by press molding from a flat thin plate of a certain thickness. The backup disk 271 has a flat end face 271a on one axial side and a flat end face 271b on the other axial side that extends parallel to the end face 271a. As shown in FIG. 7, the backup disk 271 has an inner peripheral surface 271c on the radial inside that is a cylindrical surface that is perpendicular to the end face 271a and is interrupted in the circumferential direction, and a concave portion 272 that is concave radially outward from the break in the inner peripheral surface 271c. The backup disk 271 has a plurality of concave portions 272 of the same shape formed at equal intervals in the circumferential direction, specifically three concave portions 272. Thus, the concave portions 272 are partially provided in the circumferential direction of the backup disk 271.

[0170] The recessed portion 272 penetrates the backup disk 271 in the axial direction. The recessed portion 272 has a recessed bottom surface 272a that is coaxial with the inner peripheral surface 271c and has a cylindrical surface shape with a larger diameter than the inner peripheral surface 271c, and a pair of recessed wall surfaces 272b that extend from both ends of the recessed bottom surface 272a in the circumferential direction of the backup disk 271 to the radially outer side of the backup disk 271 and connect to the inner peripheral surface 271c. The length of the recessed portion 272 in the circumferential direction of the backup disk 271 is longer than the length of one continuous portion of the inner peripheral surface 271c in the circumferential direction of the backup disk 271. The radius of the recessed bottom surface 272a of the recessed portion 272 is larger than the radius of the large-diameter inner peripheral surface 102e of the introduction member 102 shown in FIG. 6. The outer peripheral surface 271d of the backup disk 271 is a cylindrical surface coaxial with the inner peripheral surface 271c.

[0171] The inner diameter of the backup disk 271, i.e., the inner diameter of the inner peripheral surface 271c, is the same as the inner diameter of the small-diameter inner peripheral surface 102c of the introduction member 102, and the outer diameter of the backup disk 271, i.e., the outer diameter of the outer peripheral surface 271d, is larger than the outer diameter of the outer peripheral surface 102f of the introduction member 102. The inner diameter of the inner peripheral surface 271c of the backup disk 271 is smaller than the inner diameter of the large-diameter inner peripheral surface 102e of the introduction member 102.

[0172] The fitting shaft portion 97 of the piston rod 8 is fitted at its outer peripheral surface 97a into the inner peripheral surface 271c of the backup disk 271. The end surface 271a of the backup disk 271 is in surface contact with the end surface 102b of the introduction member 102. Then, the communication gaps 273 in the multiple recessed portions 272 of the backup disk 271, i.e., the communication gaps 273 between the multiple recessed portions 272 of the backup disk 271 and the fitting shaft portion 97 of the piston rod 8, communicate with the gap 110 between the introduction member 102 and the fitting shaft portion 97. In other words, the backup disk 271 has a communication gap 273 on the inner peripheral side that communicates with the gap 110.

[0173] The notched disk 103B is made of metal and is formed by pressing a flat thin plate of a certain thickness. The notched disk 103B has a flat end face 103Ba on one axial side and a flat end face 103Bb on the other axial side that extends parallel to the end face 103Ba. 8, the notched disk 103B has, on the radially inner side, an inner circumferential surface 103Bc that is a cylindrical surface that is interrupted in the circumferential direction perpendicular to the end surface 103Ba, and a recessed portion 281 that is recessed radially outward from the broken portion of the inner circumferential surface 103Bc. The notched disk 103B has a plurality of recessed portions 281 of the same shape formed at equal intervals partially in the circumferential direction, specifically three recessed portions 281.

[0174] The recessed portion 281 penetrates the cutout disk 103B in the axial direction. The recessed portion 281 has a recessed bottom surface 281a that is coaxial with the inner peripheral surface 103Bc and has a cylindrical surface shape that is discontinuous in the circumferential direction and has a larger diameter than the inner peripheral surface 103Bc, and a pair of recessed wall surfaces 281b that extend from both ends of the recessed bottom surface 281a in the circumferential direction of the cutout disk 103B to the radially outer side of the cutout disk 103B and connect to the inner peripheral surface 103Bc. The length of the recessed portion 281 in the circumferential direction of the cutout disk 103B is longer than the length of one continuous part of the inner peripheral surface 103Bc in the circumferential direction of the cutout disk 103B. The recessed bottom surface 281a of each recessed portion 281 is broken at the center position in the circumferential direction of the cutout disk 103B. The diameter of the concave bottom surface 281 a of the concave portion 281 is the same as the diameter of the concave bottom surface 272 a of the concave portion 272 of the backup disk 271 .

[0175] The notched disk 103B has a notch 121B on the radially inner side that extends radially outward from the broken portion of each concave bottom surface 281a to a radially intermediate position. The notched disk 103B has a plurality of notches 121B of the same shape formed at equal intervals in the circumferential direction, specifically three notches 121B. The notched portions 121B penetrate the notched disk 103B in the axial direction.

[0176] The diameter of the notched portion 121B in the radial direction of the notched disk 103B is larger than the diameter of the large-diameter inner circumferential surface 102e of the introduction member 102 shown in Fig. 6. In other words, the radius of the large-diameter inner circumferential surface 102e of the introduction member 102 is smaller than the distance from the center of the notched disk 103B to the outer end of the notched portion 121B in the radial direction of the notched disk 103B. The outer peripheral surface 103Bd of the notched disk 103B is a cylindrical surface coaxial with the inner peripheral surface 103Bc.

[0177] The inner diameter of the notched disk 103B, i.e., the inner diameter of the inner peripheral surface 103Bc, is the same as the inner diameter of the inner peripheral surface 271c of the backup disk 271, and the outer diameter of the notched disk 103B, i.e., the outer diameter of the outer peripheral surface 103Bd, is the same as the outer diameter of the outer peripheral surface 271d of the backup disk 271. The inner diameter of the inner peripheral surface 103Bc of the notched disk 103B is smaller than the inner diameter of the large-diameter inner peripheral surface 102e of the introduction member 102.

[0178] The fitting shaft portion 97 of the piston rod 8 is fitted at its outer peripheral surface 97a into the inner peripheral surface 103Bc of the notched disk 103B. An end surface 103Ba of the notched disk 103B comes into surface contact with an end surface 271b of the backup disk 271. Then, the passages in the plurality of notches 121B and the passages in the plurality of recesses 281 of the notched disk 103B shown in FIG. 8 communicate with the gap 110 between the introduction member 102 and the fitting shaft portion 97 via the communication gaps 273 shown in FIG. 6 in the plurality of recesses 281 of the backup disk 271 shown in FIG. 7.

[0179] The end face 104a of the retainer 104 is in surface contact with the end face 103Bb of the notched disk 103B. The retainer 104 is the same as in the first and second embodiments, and is annular as shown in Fig. 9. The inner diameter of the retainer 104, i.e., the inner diameter of the inner peripheral surface 104c, is the same as the inner diameter of the inner peripheral surface 103Bc of the notched disk 103B shown in Fig. 8. The outer diameter of the retainer 104, i.e., the outer diameter of the outer peripheral surface 104d, is smaller than the outer diameter of the outer peripheral surface 103Bd of the notched disk 103B.

[0180] At least a part of the retainer 104 has a smaller diameter than the diameter of the notched portion 121B in the radial direction of the notched disk 103B. Specifically, the outer peripheral surface 104d of the retainer 104 has a smaller diameter than the diameter of the notched portion 121B in the radial direction of the notched disk 103B over the entire circumference. In other words, the distance from the center of the retainer 104 to the outer peripheral surface 104d, i.e., the radius, is smaller than the distance from the center of the notched disk 103B to the outer end of the notched portion 121B in the radial direction of the notched disk 103B. Therefore, the passages in the multiple notched portions 121B of the notched disk 103B communicate with the first chamber 11 in the part of the notched disk 103B that is outside the retainer 104 in the radial direction, as shown in FIG. 6. The retainer 104 supports the notched disk 103B relative to the backup disk 271 and the introducing member 102.

[0181] As shown in Fig. 6, the gap 110 between the introduction member 102 and the fitting shaft portion 97, the communicating gap 273 in the multiple recesses 272 of the backup disk 271, the passages in the multiple recesses 281 of the cut-out disk 103B shown in Fig. 8, and the passages in the multiple cut-outs 121B of the cut-out disk 103B constitute an orifice 111B that communicates between the rod passage 57 and the first chamber 11. Of the passages in the multiple cut-outs 121B of the orifice 111B, the flow path area of ​​the portion sandwiched between the end face 271b of the backup disk 271 and the end face 104a of the retainer 104 is the narrowest.

[0182] The introduction member 102, the backup disk 271, the notched disk 103B, and the retainer 104 constitute an orifice mechanism 112B that defines an orifice 111B that connects the rod passage 57 and the first chamber 11. In other words, the orifice mechanism 112B includes an introduction member 102 through which the mounting shaft portion 40 of the piston rod 8 is inserted and which has a gap 110 on its inner peripheral side that communicates with the rod passage 57, a notched disk 103B through which the mounting shaft portion 40 of the piston rod 8 is inserted and which has a notched portion 121B that guides oil liquid L as a working fluid from the first chamber 11 to the gap 110, a retainer 104 through which the mounting shaft portion 40 of the piston rod 8 is inserted and which abuts against the notched disk 103B and supports the notched disk 103B against the introduction member 102, and at least a portion of which has a smaller diameter than the notched portion 121B, and a backup disk 271 which is provided between the introduction member 102 and the notched disk 103B and which has a communicating gap 273 on its inner peripheral side that communicates with the gap 110. The orifice mechanism 112B has an orifice 111B that guides oil L as a working fluid from the first chamber 11 to the rod passage 57, i.e., the variable damping force mechanism 58 (see Figure 2), and also guides oil L from the rod passage 57, i.e., the variable damping force mechanism 58 (see Figure 2), to the first chamber 11.

[0183] The damping valve 91 is provided between the introduction member 102B of the orifice mechanism 112B and the piston 9. In the orifice mechanism 112B, a notched disk 103B is provided on the damping valve 91 side of the introduction member 102B. In the orifice mechanism 112B, a retainer 104 is provided on the damping valve 91 side of the introduction member 102B. In the orifice mechanism 112B, the retainer 104 is provided on the damping valve 91 side of the notched disk 103B.

[0184] The shock absorber 1B of the third embodiment operates in the same manner as the shock absorber 1 of the first embodiment, except that the oil L flows between the first chamber 11 and the rod passage 57 via an orifice 111B provided in place of the orifice 111.

[0185] The shock absorber 1B of the third embodiment includes a rod passage 57 that introduces oil L as a working fluid to a damping force variable mechanism 58 (see FIG. 2) that is a device provided in the piston rod 8, and an orifice mechanism 112B that introduces the oil L as a working fluid from the first chamber 11 to the rod passage 57. The orifice mechanism 112B of the shock absorber 1B includes an introduction member 102B having a gap 110B that communicates with the rod passage 57 on its inner periphery, a notched disk 103B having a notched portion 121B that introduces the oil L as a working fluid from the first chamber 11 to the gap 110B, and a retainer 104 that supports the notched disk 103B relative to the introduction member 102B and has at least a portion having a smaller diameter than the notched portion 121B.

[0186] Therefore, since the shock absorber 1B has the notched disk 103B provided between the introduction member 102B and the retainer 104, it has the same effects as the shock absorber 1 of the first embodiment.

[0187] In addition, the shock absorber 1B is provided with a backup disk 271 between the introduction member 102 and the notched disk 103B, which has a communication gap 273 on the inner periphery side that communicates with the gap 110. Therefore, the notched portion 121B of the notched disk 103B does not directly contact the end face 102b on the side of the large-diameter inner periphery surface 102e of the introduction member 102B, whose inner diameter is enlarged. This makes it possible to suppress the fastening surface from being deformed along the notched portion 121B due to the axial fastening force, resulting in a deterioration in performance quality. That is, in the first and second embodiments, the plate thickness of the notched disk 103 is changed to sufficiently reduce the width of the notched portion 121B to ensure the area, but in the third embodiment, a structure is adopted in which a backup disk 271 without a notch is sandwiched between the notched disk 103B and the introduction member 102B, thereby making it possible to suppress the deterioration in performance quality due to the deformation of the fastening surface.

[0188] Here, in order to ensure a flow path from notch 121B to gap 110 in introduction member 102, shock absorber 1B has an expanded inner diameter partially, leaving only three places on the inner periphery, such as central notched disk 103B and backup disk 271 without a notch, and the circumferential lengths of the three places are set by adjusting the plate thickness so as to ensure a flow path even if notched disk 103 and backup disk 271 are out of phase. The structure of shock absorber 1B is particularly effective when the pressure loss in the flow path is small, i.e., when the area of ​​notch 121B is set to a relatively small size.

[0189] It is also possible to provide a similar backup disk 271 between the introduction member 102 and the notched disk 103 of the shock absorber 1 of the first embodiment. It is also possible to provide a similar backup disk 271 between the introduction member 102A and the notched disk 103 of the shock absorber 1A of the second embodiment.

[0190] In the above first to third embodiments of the shock absorbers 1, 1A, and 1B, the introduction members 102, 102A are described as being annular in shape, but the introduction members 102, 102A do not have to be annular in shape, and may have, for example, an angular outer circumferential surface.

[0191] Further, in the shock absorbers 1, 1A, 1B of the first to third embodiments, the gaps 110, 110A are annular in shape. However, the gaps 110, 110A may be provided partially in the circumferential direction of the introduction members 102, 102A.

[0192] In addition, in the shock absorbers 1, 1A, 1B of the first to third embodiments, the rod passage 57 connecting the gaps 110, 110A and the housing interior passage 241 of the damping force variable mechanism 58 has been described as passing through the mounting shaft portion 40 of the piston rod 8 as an example, but it is also possible to form such a rod passage by cutting out the outer periphery of the mounting shaft portion 40 of the piston rod 8 in a flat shape, or by providing a groove on the outer periphery of the mounting shaft portion 40.

[0193] In addition, in the shock absorbers 1, 1A, and 1B of the first to third embodiments, the notched disk 103 or the notched disk 103B is used, but other notched members may be used instead of the notched disk 103 as long as a groove corresponding to the notched portion 121 is formed, and other notched members may be used instead of the notched disk 103B as long as a groove corresponding to the notched portion 121B is formed. These notched members are, for example, annular members having a thickness greater than that of the notched disks 103 and 103B. Note that it is preferable to use the notched disk 103 or the notched disk 103B as in the shock absorbers 1, 1A, and 1B of the first to third embodiments, because this shortens the axial length of the shock absorbers 1, 1A, and 1B and reduces costs. [Explanation of symbols]

[0194] 1,1A,1B...shock absorber, 4...cylinder, 8...piston rod, 9...piston, 11...first chamber (chamber), 12...second chamber (chamber), 50...piston passage, 57...rod passage, 58...variable damping force mechanism (device), 91...damping valve, 102...introduction member, 103,103B...notched disc (notched member), 104...retainer, 110...gap, 112...orifice mechanism, 121,121B...notched portion, 271...backup disc, 273...communicating gap.

Claims

1. A cylinder in which a working fluid is sealed; A piston that divides the inside of the cylinder into two chambers; a piston rod having one end fixed to the piston and the other end extending from the cylinder; A device provided on one side of the piston; a piston passage provided in the piston; a rod passage provided in the piston rod for directing a working fluid to the device; an orifice mechanism for directing hydraulic fluid from the chamber to the rod passage; Equipped with The orifice mechanism includes: an introduction member having a gap on an inner circumferential side thereof communicating with the rod passage; a notch member having a notch portion for guiding the working fluid from the chamber to the gap; a retainer that supports the notched member relative to the introduction member and has at least a portion having a smaller diameter than the notched portion; A shock absorber having a shock absorber.

2. a damping valve provided between the introduction member and the piston for opening and closing the piston passage, The retainer is provided on the damping valve side of the introduction member. The shock absorber according to claim 1.

3. a damping valve provided between the introduction member and the piston for opening and closing the piston passage, The retainer is provided on the opposite side of the introduction member to the damping valve. The shock absorber according to claim 1.

4. A backup disk having a communication gap on its inner periphery that communicates with the gap is provided between the introduction member and the notch member. A shock absorber according to any one of claims 1 to 3.

5. The notched member is a notched disk. A shock absorber according to any one of claims 1 to 3.

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