Shock absorber

Abstract

This shock absorber comprises: a cylinder in which a working fluid is sealed; a piston that is slidably fitted into the cylinder and partitions the inside of the cylinder into a chamber on one side and a chamber on the other side; a first passage and a second passage through which the working fluid flows, due to the movement of the piston, from the chamber on the upstream side to the chamber on the downstream side inside the cylinder; a first damping force generating mechanism that is provided in the first passage and generates a damping force; and a second damping force generating mechanism that is disposed inside the piston and is disposed inside a passage hole that constitutes the second passage parallel to the first passage.

Description

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

[0002] 2. Description of the Related Art Some shock absorbers have two valves arranged in parallel that open during the same stroke (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-5202

[0004] In shock absorbers, there is a demand for miniaturization of the structure around the piston that is slidably provided in the cylinder.

[0005] Therefore, an object of the present disclosure is to provide a shock absorber that enables the configuration around the piston to be miniaturized.

[0006] In order to achieve the above object, one aspect of the shock absorber of the present disclosure includes a cylinder filled with working fluid, a piston slidably fitted within the cylinder and dividing the interior of the cylinder into one side chamber and another side chamber, a first passage and a second passage through which working fluid flows from an upstream chamber within the cylinder to a downstream chamber as the piston moves, a first damping force generating mechanism provided in the first passage and generating a damping force, and a second damping force generating mechanism disposed inside the piston and disposed within a passage hole that constitutes the second passage that is parallel to the first passage.

[0007] According to the present disclosure, the configuration around the piston can be made smaller.

[0008] 1 is a partial view showing a shock absorber of a first embodiment according to the present disclosure. FIG. 1 is a partial cross-sectional view showing a main portion of the shock absorber. FIG. 2 is a partial cross-sectional view showing a main portion of the shock absorber. FIG. 3 is a partial enlarged cross-sectional view showing a main portion of the shock absorber. FIG. 2 is a partial enlarged ...3 is a partial enlarged cross-sectional view showing a main portion of the shock absorber. FIG. 4 is a hydraulic circuit diagram showing the shock absorber. FIG. 5 is a hydraulic circuit diagram showing a modified example of the shock absorber according to the present disclosure. FIG. 6 is a hydraulic circuit diagram showing a modified example of the shock absorber according to the present disclosure. FIG. 7 is a partial cross-sectional view showing a main portion of the shock absorber of a second embodiment according to the present disclosure. FIG. 11 is a partial enlarged cross-sectional view showing a main portion of the shock absorber. FIG. 12 is a partial enlarged cross-sectional view showing a main portion of the shock absorber. FIG. 11 is a partial enlarged cross-sectional view showing a main portion of the shock absorber.

[0009] [First embodiment] A shock absorber according to a first embodiment of the present disclosure will be described with reference to Figures 1 to 10. Note that, for ease of explanation, the upper side in Figures 1 to 3, 11, and 12 will be referred to as "upper," and the lower side in Figures 1 to 3, 11, and 12 will be referred to as "lower."

[0010] 1 is a shock absorber used in suspension devices for railway vehicles and automobiles such as two-wheeled and four-wheeled vehicles, and more specifically, a shock absorber used in suspension devices for four-wheeled automobiles. The shock absorber 1 has a cylinder 11. Here, the shock absorber 1 will be described as being applied to a mono-cylinder shock absorber configuration having one cylinder 11, but this configuration can also be applied to a twin-cylinder shock absorber in which a shell is provided around the cylinder 11 to form a reservoir chamber between the shell and the cylinder 11, and a base valve is provided between the reservoir chamber and a chamber inside the cylinder 11.

[0011] The cylinder 11 has a cylindrical body 12 and a bottom (not shown) that closes the lower part of one axial end of the body, and the upper part of the other axial end of the body is an opening (not shown).

[0012] The shock absorber 1 has a piston 15 slidably provided within the body 12 of the cylinder 11, and a free piston (not shown) slidably provided within the body 12 of the cylinder 11. The free piston (not shown) is provided closer to the bottom (not shown) in the axial direction of the cylinder 11 than the piston 15. The piston 15 divides the interior of the cylinder 11 into a first chamber 21 on the opposite side from the free piston (not shown), and a second chamber 22 between the piston 15 and the free piston (not shown). The free piston (not shown) forms a third chamber (not shown) between itself and the bottom (not shown) of the cylinder, dividing the interior of the cylinder into the second chamber and the third chamber (not shown).

[0013] The shock absorber 1 has a piston rod 31 connected to the piston 15. The piston 15 is fixed to one axial end of the piston rod 31, and the other axial end side extends to the outside of the cylinder 11 from an opening (not shown) at the top of the cylinder 11.

[0014] The shock absorber 1 has, at an opening (not shown) in the upper part of the cylinder 11, a rod guide (not shown) that restricts radial movement of the piston rod 31 relative to the cylinder 11 while allowing axial movement relative to the cylinder 11, and a sealing member (not shown) that seals the gap between the opening (not shown) of the cylinder 11 and the piston rod 31 while allowing axial movement of the piston rod 31 relative to the cylinder 11. The rod guide (not shown) is provided closer to the piston 15 in the axial direction than the sealing member (not shown), and forms the above-mentioned first chamber 21 between the rod guide and the piston 15.

[0015] In the cylinder 11, a first chamber 21 and a second chamber 22 are filled with oil L as a working fluid, and a third chamber (not shown) is filled with gas.

[0016] The piston rod 31 has a cylindrical main shaft portion 32 and a mounting shaft portion 33 provided on one axial end of the main shaft portion 32. The outer diameter of the main shaft portion 32 is larger than that of the mounting shaft portion 33. The axial end face of the main shaft portion 32 facing the mounting shaft portion 33 is flat and extends perpendicular to the central axis of the piston rod 31. The mounting shaft portion 33 of the piston rod 31 is inserted into the cylinder 11 and connected to the piston 15, and the main shaft portion 32 extends to the outside from an opening of the cylinder through a rod guide and a seal member (not shown). The piston rod 31 penetrates the first chamber 21 but does not penetrate the second chamber 22. A male thread portion 34 is formed on the outer periphery of the mounting shaft portion 33 at the end opposite the main shaft portion 32 in the axial direction. A nut 38 is threadedly engaged with the male thread portion 34 to secure the piston 15 to the piston rod 31.

[0017] The piston 15 and piston rod 31 move together. During the extension stroke of the shock absorber 1, in which the piston rod 31 protrudes more from the cylinder 11, the piston 15 moves toward the first chamber 21, and during the compression stroke of the shock absorber 1, in which the piston rod 31 protrudes less from the cylinder 11, the piston 15 moves toward the second chamber 22. When the amount of penetration of the piston rod 31 into the cylinder 11 decreases during the extension stroke, the free piston (not shown) moves toward the side opposite the bottom (not shown) of the cylinder 11 to increase the volume of the third chamber (not shown), and when the amount of penetration of the piston rod 31 into the cylinder 11 increases during the compression stroke, the free piston (not shown) moves toward the bottom (not shown) of the cylinder 11 to decrease the volume of the third chamber (not shown).

[0018] When the shock absorber 1 is attached to a vehicle, for example, the portion of the piston rod 31 protruding from the cylinder 11 is arranged at the top and connected to the vehicle body side, and the cylinder 11 is arranged at the bottom and connected to the wheel side. Conversely, the cylinder 11 side may be arranged at the top and connected to the vehicle body side, and the portion of the piston rod 31 protruding from the cylinder 11 may be arranged at the bottom and connected to the wheel side.

[0019] 2 and 3, the piston 15 is disk-shaped and has a through-hole 41 formed in its radial center that penetrates in the axial direction. The piston 15 is attached to the piston rod 31 with the mounting shaft portion 33 of the piston rod 31 fitted into the through-hole 41. The piston 15 has, in this order from the through-hole 41 side at the radial center toward the radial outside, a boss portion 42, an inner passage-forming portion 43, and an outer passage-forming portion 44.

[0020] The boss portion 42 is cylindrical and has a through hole 41 formed in the center in the radial direction. The boss portion 42 is mirror-symmetrical in the axial direction of the piston 15.

[0021] The inner passage forming portion 43 has an axial length shorter than that of the boss portion 42, is provided at the axial center of the boss portion 42, and is formed in a disk shape extending radially outward from the boss portion 42. The inner passage forming portion 43 is mirror-symmetrical in the axial direction of the piston 15. The inner passage forming portion 43 has a main body portion 51, inner seat portions 52, 53, outer seat portions 54, and outer seat portions 55.

[0022] The main body 51 is in the shape of a disk with a constant thickness.

[0023] The inner seat portion 52 is annular and coaxial with the main body portion 51, and is located at the boundary between the upper surface of the main body portion 51 and the boss portion 42 on the inner periphery thereof, and protrudes upward in the axial direction beyond the upper surface of the main body portion 51.

[0024] The inner seat portion 53 is annular and coaxial with the main body portion 51, and is provided at the boundary between the lower surface of the main body portion 51 and the boss portion 42 on the inner periphery thereof, and protrudes downward, i.e., the other axial direction side, beyond the lower surface of the main body portion 51. The inner seat portions 52, 53 protrude evenly from the main body portion 51 in the axial direction.

[0025] The outer seat portion 54 is annular and coaxial with the main body portion 51, and is located at the boundary between the outer passage forming portion 44 on the outer periphery of the upper surface of the main body portion 51 and the outer seat portion 54, and protrudes upward in the axial direction beyond the upper surface of the main body portion 51.

[0026] The outer seat portion 55 is annular and coaxial with the main body portion 51, and is provided at the boundary between the outer passage-forming portion 44 and the outer peripheral side of the underside of the main body portion 51, protruding downward, i.e., the other axial direction side, beyond the underside of the main body portion 51. The outer seat portions 54, 55 protrude evenly in the axial direction from the main body portion 51. The outer seat portion 54 protrudes axially to a height equal to or greater than that of the inner seat portion 52. The outer seat portion 55 protrudes axially to a height equal to or greater than that of the inner seat portion 53 from the main body portion 51.

[0027] An inner passage hole 57 is formed in the main body 51 between the radially inner seat portions 52, 53 and the radially outer seat portions 54, 55, penetrating the main body 51 in the axial direction. The main body 51 is formed with a plurality of inner passage holes 57 at equal intervals in the circumferential direction.

[0028] The outer passage forming portion 44 has an annular shape and protrudes from the inner passage forming portion 43 on both axial sides of the inner passage forming portion 43. The outer passage forming portion 44 is formed with a first passage hole 61 (shown in FIG. 2 ) that penetrates the outer passage forming portion 44 in the axial direction, and a first passage hole 62 (shown in FIG. 3 ) that penetrates the outer passage forming portion 44 in the axial direction. The outer passage forming portion 44 is formed with a plurality of first passage holes 61 (shown in FIG. 2 ) that are equally spaced apart in the circumferential direction. The outer passage forming portion 44 is formed with a plurality of first passage holes 62 (shown in FIG. 3 ) that are equally spaced apart in the circumferential direction. The first passage holes 61 (shown in FIG. 2 ) and the first passage holes 62 (shown in FIG. 3 ) are arranged alternately in the circumferential direction at equally spaced intervals.

[0029] In the piston 15, the upper part of the boss portion 42, the upper part of the outer passage-forming portion 44, and the upper part of the inner passage-forming portion 43 form a recessed portion 65 that is recessed from the top to the bottom of the boss portion 42 and the outer passage-forming portion 44 toward the inner passage-forming portion 43 in the axial direction. The recessed portion 65 is also annular. A plurality of inner passage holes 57 open in the bottom surface of this recessed portion 65.

[0030] In the piston 15, the lower part of the boss portion 42, the lower part of the outer passage-forming portion 44, and the lower part of the inner passage-forming portion 43 form a recessed portion 66 that is recessed from the bottom to the top from the boss portion 42 and the outer passage-forming portion 44 toward the inner passage-forming portion 43 in the axial direction. The recessed portion 66 is also annular. A plurality of inner passage holes 57 open in the bottom surface of this recessed portion 66.

[0031] In other words, the upper recessed portion 65 and the lower recessed portion 66 are connected to each other by the plurality of inner passage holes 57. The recessed portions 65, 66, and the plurality of inner passage holes 57 constitute a second passage hole 68 (passage hole) formed in the piston 15 so as to penetrate the piston 15 in the axial direction.

[0032] As shown in FIG. 2 , a passage groove 71 is formed in the upper part of the outer passage forming portion 44 at a portion where the first passage holes 61 and the outer passage forming portion 44 are aligned in the circumferential direction. The passage groove 71 is recessed downward from the upper end surface of the outer passage forming portion 44. The passage groove 71 is formed to correspond to each of the first passage holes 61. Thus, a plurality of passage grooves 71 are provided at equal intervals in the circumferential direction of the outer passage forming portion 44. The first passage holes 61 open at the bottom surfaces of all of the passage grooves 71. The passage groove 71 is constantly in communication with the first chamber 21, and communicates the first chamber 21 with the first passage holes 61 and the recessed portion 65.

[0033] As shown in FIG. 3 , a passage groove 72 is formed in the lower part of the outer passage forming portion 44, radially penetrating the outer passage forming portion 44, at a portion where the first passage holes 62 and the outer passage forming portion 44 are aligned in the circumferential direction. The passage groove 72 is recessed upward from the lower end surface of the outer passage forming portion 44. The passage groove 72 is formed to correspond to each of the first passage holes 62. Thus, a plurality of passage grooves 72 are provided at equal intervals in the circumferential direction of the outer passage forming portion 44. The first passage holes 62 open at the bottom surfaces of all of the passage grooves 72. The passage groove 72 is constantly in communication with the second chamber 22, and communicates the second chamber 22 with the first passage holes 62 and the recessed portion 66.

[0034] 2, the lower portion of the outer passage forming portion 44 excluding the passage grooves 72 serves as an outer passage seat portion 75. All of the first passage holes 61 open to the outer passage seat portion 75.

[0035] 3, the upper portion of the outer passage forming portion 44, excluding the passage grooves 71, constitutes an outer passage seat portion 76. All of the first passage holes 62 open to the outer passage seat portion 76.

[0036] As shown in Figures 2 and 3, the shock absorber 1 has, below the outer passage forming portion 44 and the boss portion 42, a main valve 82 consisting of a plurality of perforated, circular flat disks 81, a plurality of perforated, circular flat disks 83, and a single perforated, circular flat washer 84, in that order from the piston 15 side in the axial direction. The main valve 82 consisting of the plurality of disks 81, the plurality of disks 83, and the washer 84 are all made of metal, and the mounting shaft portion 33 of the piston rod 31 is fitted into their respective radially inner sides. As shown in Figure 1, the washer 84 abuts against the nut 38 that threads onto the male thread portion 34 of the piston rod 31. At least the inner peripheral sides of the plurality of disks 81, the plurality of disks 83, and the washer 84 shown in Figures 2 and 3 are clamped in the axial direction by the boss portion 42 of the piston 15 and the nut 38 shown in Figure 1.

[0037] 2 and 3, the outer diameters of the plurality of discs 81 constituting the main valve 82 generally increase as they approach the piston 15 in the axial direction. Of the plurality of discs 81 constituting the main valve 82, the disc 81 with the largest outer diameter that is axially closest to the piston 15 has an outer diameter that abuts against the outer passage seat portion 75 of the outer passage forming portion 44 of the piston 15 and closes all of the first passage holes 61.

[0038] The outer diameters of the plurality of discs 83 are smaller than the outer diameter of the smallest outer diameter disc 81 of the plurality of discs 81 constituting the main valve 82 that is located furthest away from the piston 15 in the axial direction.

[0039] The washer 84 has an outer diameter larger than that of the plurality of discs 83, and is thicker and more rigid than the plurality of discs 81 that constitute the main valve 82.

[0040] The main valve 82 closes the first passage hole 61 by being seated on the outer passage seat portion 75 of the piston 15. The main valve 82 opens the first passage hole 61 to the second chamber 22 by being lifted off the outer passage seat portion 75. The first passage hole 61 is constantly in communication with the first chamber 21 due to the formation of the passage grooves 71. The passages in the multiple passage grooves 71 and the multiple first passage holes 61 form a first passage 86 that can communicate between the first chamber 21 and the second chamber 22, and the main valve 82 opens and closes this first passage 86. The main valve 82 and the outer passage seat 75 are provided in the first passage 86 and open and close the first passage 86, constituting a first damping force generating mechanism 87 that, when open, causes oil liquid L to flow from the first chamber 21 to the second chamber 22 and generates a damping force. Since the first damping force generating mechanism 87 is provided on the second chamber 22 side, the first passage 86 serves as a passage through which oil L flows from the first chamber 21, which is on the upstream side, to the second chamber 22, which is on the downstream side, as the piston 15 moves during the extension stroke, and the first damping force generating mechanism 87, which opens and closes this first passage 86, serves as an extension-side damping force generating mechanism. The first damping force generating mechanism 87 restricts the flow of oil L from the second chamber 22 toward the first chamber 21 via the first passage 86. The first passage 86 and the first damping force generating mechanism 87 are provided in the piston 15.

[0041] The shock absorber 1 has, above the outer passage forming portion 44 and the boss portion 42, a main valve 92 consisting of a plurality of perforated, circular flat disks 91, a plurality of perforated, circular flat disks 93, and a single perforated, circular flat washer 94, in this order from the piston 15 side in the axial direction. The main valve 92 consisting of the plurality of disks 91, the plurality of disks 93, and the washer 94 are all made of metal, and the mounting shaft portion 33 of the piston rod 31 is fitted into their respective radially inner sides. As shown in FIG. 1, the washer 94 abuts on the end surface of the main shaft portion 32 of the piston rod 31 that faces the mounting shaft portion 33 in the axial direction. As shown in FIG. 3, at least the inner peripheral sides of the washer 94, the plurality of disks 93, and the plurality of disks 91 are clamped in the axial direction by the boss portion 42 of the piston 15 and the main shaft portion 32 of the piston rod 31 shown in FIG. 1.

[0042] The plurality of discs 91 constituting the main valve 92 generally have larger outer diameters as they move axially closer to the piston 15. Of the plurality of discs 91 constituting the main valve 92, the disc 91 with the largest outer diameter that is axially closest to the piston 15 has an outer diameter that abuts against the outer passage seat portion 76 of the outer passage forming portion 44 of the piston 15 and closes all of the first passage holes 62.

[0043] The plurality of discs 93 have an outer diameter smaller than that of the disc 91 that is the smallest in outer diameter and is located axially farthest from the piston 15 among the plurality of discs 91 that constitute the main valve 92 .

[0044] The washer 94 has an outer diameter larger than that of the plurality of discs 93, and is thicker and more rigid than the plurality of discs 91 that constitute the main valve 92.

[0045] The main valve 92 closes the first passage hole 62 by being seated on the outer passage seat 76. The main valve 92 opens the first passage hole 62 to the first chamber 21 by being lifted off the outer passage seat 76. The passage grooves 72 are formed so that the first passage hole 62 is constantly in communication with the second chamber 22. The passages in the passage grooves 72 and the first passage holes 62 form a first passage 96 that can communicate between the second chamber 22 and the first chamber 21, and the main valve 92 opens and closes this first passage 96. The main valve 92 and the outer passage seat 76 are provided in the first passage 96 and open and close the first passage 96, constituting a first damping force generating mechanism 97 that, when open, causes oil liquid L to flow from the second chamber 22 to the first chamber 21 and generates a damping force. Since the first damping force generating mechanism 97 is provided on the first chamber 21 side, the first passage 96 serves as a passage through which oil L flows from the second chamber 22, which is on the upstream side, to the first chamber 21, which is on the downstream side, as the piston 15 moves during the compression stroke, and the first damping force generating mechanism 97, which opens and closes this first passage 96, serves as a compression-side damping force generating mechanism. The first damping force generating mechanism 97 restricts the flow of oil L from the first chamber 21 toward the second chamber 22 via the first passage 96. The first passage 96 and the first damping force generating mechanism 97 are provided in the piston 15.

[0046] As shown in Figures 4 and 5, the shock absorber 1 is located between the upper part of the outer passage forming portion 44 and the upper part of the boss portion 42 in the radial direction of the piston 15, and between the piston 15 and the main valve 92 in the axial direction of the piston 15, and includes, in order from the main valve 92 side in the axial direction, a plurality of discs 101, one orifice disc 102 (first orifice member), one disc 103, one spring disc 104, one valve disc 105, one chamber forming disc 106, one spacer 107, one passage disc 108, one passage disc 109, one orifice disc 110, one seat disc 111, and one valve disc 112.

[0047] The disk 101, orifice disk 102, disk 103, spring disk 104, valve disk 105, chamber forming disk 106, spacer 107, passage disk 108, passage disk 109, orifice disk 110 and seat disk 111 are all annular, and a portion above the inner passage forming portion 43 of the boss portion 42 of the piston 15 is fitted into the radially inner side of each of them. The valve disk 112 is annular, and the inner seat portion 52 of the piston 15 is inserted into the radially inner side of each of them.

[0048] The disk 101 is a perforated corrugated metal disk, and has an outer diameter that is approximately equal to the outer diameter of the inner seat portion 52 of the piston 15 and the outer diameter of the disk 93 .

[0049] The orifice disk 102 is a metal, circular, flat plate with holes, and its outer diameter is larger than that of the disk 101 and slightly smaller than the inner diameter of the outer passage-forming portion 44 of the piston 15. The orifice disk 102 is formed with a first orifice 121 penetrating the orifice disk 102 in the axial direction, i.e., the thickness direction, at a radially intermediate position between the inner and outer peripheries. The orifice disk 102 is formed with a plurality of first orifices 121 at equal intervals around the periphery of the orifice disk 102. The disk 101 has an outer diameter that does not narrow or close these first orifices 121. The orifice disk 102 faces the first chamber 21, and the first orifice 121 communicates with the first chamber 21 via a plurality of passage grooves 71 in the piston 15.

[0050] The disk 103 is a metal, circular, flat plate with holes, and has an outer diameter equal to that of the disk 101. Therefore, the disk 103 also has an outer diameter that does not narrow or close the first orifice 121 of the orifice disk 102.

[0051] The spring disc 104 is made of metal and has a perforated circular flat base plate portion 125 and spring plate portions 126 extending radially outward from the base plate portion 125. A plurality of spring plate portions 126 are provided on the base plate portion 125 at equal intervals in the circumferential direction of the base plate portion 125. The spring disc 104 has a boss portion 42 of the piston 15 fitted into the radially inner side of the base plate portion 125. The outer diameter of the base plate portion 125 of the spring disc 104 is equal to or greater than the outer diameter of the disc 103. The plurality of spring plate portions 126 are bent so that intermediate positions in the radial direction of the base plate portion 125 protrude from the base plate portion 125 toward the orifice disc 102 in the axial direction of the base plate portion 125.

[0052] The valve disc 105 is a perforated, circular, flat metal plate with an outer diameter larger than the overall outer diameter of the spring disc 104. A through-hole 131 is formed in the valve disc 105 at a radially intermediate position between the inner and outer peripheries, penetrating the valve disc 105 in the axial direction, i.e., the thickness direction. A plurality of through-holes 131 are formed in the valve disc 105.

[0053] The chamber-forming disk 106 has a metal disk 135 and a seal portion 136 made of an elastic sealing material such as rubber.

[0054] The disk 135 is a circular, flat plate with holes, and its outer diameter is larger than that of the valve disk 105. The disk 135 has a through-hole 141 formed in the disk 135 at a radially intermediate position between its inner and outer peripheries, penetrating the disk 135 in the axial direction, i.e., in the thickness direction. A plurality of through-holes 141 are formed in the disk 135 at equal intervals around the circumference of the disk 135. When the valve disk 105 abuts against the disk 135 of the chamber-forming disk 106, it closes the plurality of through-holes 141 in the disk 135. The plurality of spring plate portions 126 of the spring disk 104 urge the valve disk 105 so that the entire surface of the valve disk 105 abuts against the disk 135 of the chamber-forming disk 106.

[0055] The seal portion 136 is fixed by baking using vulcanization adhesion to the surface of the disk 135 opposite the valve disk 105 in the axial direction. The seal portion 136 is formed so as to surround the multiple through holes 141 on the outer side in the radial direction of the disk 135. The seal portion 136 is cylindrical, and its overall shape narrows as it moves away from the disk 135 in the axial direction of the disk 135.

[0056] The spacer 107 is annular and made of metal, and has an outer diameter smaller than the overall inner diameter of the seal portion 136 of the chamber-forming disk 106. The spacer 107 has an outer diameter that does not narrow or close the through-hole 141 of the disk 135. The thickness, i.e., the axial length, of the spacer 107 is shorter than the axial length of the seal portion 136 in its natural state before the chamber-forming disk 106 is assembled.

[0057] The passage disk 108 is annular and made of metal, and its outer diameter is larger than the outer diameter of the end of the seal portion 136 of the chamber forming disk 106 on the axially opposite side of the disk 135. The seal portion 136 of the chamber forming disk 106 abuts against the passage disk 108 over the entire circumference while elastically deforming in the axial direction. A through hole 145 penetrating the passage disk 108 in the axial direction, i.e., in the thickness direction, is formed in the passage disk 108 at a radially intermediate position between the inner peripheral portion and the outer peripheral portion. A plurality of through holes 145 are formed in the passage disk 108 at equal intervals in the circumferential direction of the passage disk 108. The plurality of through holes 145 are formed radially inward of the abutting portion of the seal portion 136 of the passage disk 108.

[0058] The passage disk 109 is annular and made of metal, and its outer diameter is smaller than that of the passage disk 108. A through hole 148 is formed in the passage disk 109 at a radially intermediate position between the inner periphery and the outer periphery, penetrating the passage disk 109 in the axial direction, i.e., in the thickness direction. A plurality of through holes 148 are formed in the passage disk 109 at equal intervals in the circumferential direction of the passage disk 109. The through holes 148 in the passage disk 109 communicate with the through holes 145 in the passage disk 108.

[0059] The orifice disk 110 is annular and made of metal, and its outer diameter is larger than that of the passage disk 109 and larger than the inner diameter of the outer seat portion 54 of the piston 15. The orifice disk 110 is formed with second orifices 151 penetrating the orifice disk 110 in the axial direction, i.e., the thickness direction, at a radially intermediate position between the inner and outer peripheries. A plurality of second orifices 151 are formed in the orifice disk 110 at equal intervals around the circumference of the orifice disk 110. The orifice disk 110 is formed with through holes 152 penetrating the orifice disk 110 in the axial direction, i.e., the thickness direction, at a radially intermediate position between the inner and outer peripheries, radially inward of the second orifices 151. A plurality of through holes 152 are formed in the orifice disk 110 at equal intervals around the circumference of the orifice disk 110. The through holes 152 of the orifice disk 110 communicate with the through holes 148 of the passage disk 109 .

[0060] The seat disk 111 is annular and made of metal, and its outer diameter is equal to that of the orifice disk 110 and larger than the inner diameter of the outer seat portion 54 of the piston 15. A through hole 156 is formed in the seat disk 111 at a radially intermediate position between the inner and outer peripheries, penetrating the seat disk 111 in the axial direction, i.e., in the thickness direction. A plurality of through holes 156 are formed in the seat disk 111 at equal intervals around the circumference of the seat disk 111. The through holes 156 communicate with the second orifice 151 of the orifice disk 110. A through hole 157 is formed in the seat disk 111 at a radially intermediate position between the inner and outer peripheries, radially inward of the through hole 156, penetrating the seat disk 111 in the axial direction, i.e., in the thickness direction. A plurality of through holes 157 are formed in the seat disk 111 at intervals around the circumference of the seat disk 111. The through hole 157 of the seat disk 111 communicates with the through hole 152 of the orifice disk 110. The outer periphery of the seat disk 111, which is radially outward of the through hole 156, abuts against the outer seat portion 54 of the piston 15 over the entire periphery.

[0061] The valve disc 112 is made of metal and has a valve plate portion 161 in the form of a circular flat plate with holes, and a spring plate portion 162 extending axially from the inner periphery of the valve plate portion 161. The spring plate portion 162 is formed by cutting and raising the inner periphery of the valve plate portion 161. A plurality of spring plate portions 162 are provided on the valve plate portion 161 at equal intervals in the circumferential direction of the valve plate portion 161. The portion of the valve plate portion 161 formed by cutting and raising the spring plate portion 162 forms a notch portion 163 that penetrates the valve plate portion 161 in the axial direction, i.e., in the plate thickness direction.

[0062] At least the inner peripheral sides of the disk 101, orifice disk 102, disk 103, spring disk 104, valve disk 105, chamber-forming disk 106, spacer 107, passage disk 108, passage disk 109, orifice disk 110, and seat disk 111, together with the main valve 92, are axially clamped to the disk 93 and the inner seat portion 52 of the piston 15. At this time, the seat disk 111 abuts against the inner seat portion 52 and the outer seat portion 54 of the piston 15 in the axial direction.

[0063] The valve plate portion 161 abuts against the seat disc 111 to close the through hole 156 of the seat disc 111. When the valve plate portion 161 moves away from the seat disc 111 in the axial direction of the seat disc 111, the valve plate portion 161 opens the through hole 156 of the seat disc 111.

[0064] The plurality of spring plate portions 162 abut against the bottom surface of the recessed portion 65 of the piston 15 and urge the valve plate portion 161 in a direction in which it abuts against the seat disc 111 and closes the through hole 156 of the seat disc 111 .

[0065] Within the recessed portion 65 of the piston 15, between the axial orifice disc 102 and the outer seat portion 54, and between the radial outer passage forming portion 44 and the disc 103, the spring disc 104, the valve disc 105, the chamber forming disc 106, the passage disc 108, the passage disc 109, the orifice disc 110 and the seat disc 111, there is formed an outer volume chamber 171 (volume chamber) which is connected to the first chamber 21 via the first orifice 121 of the orifice disc 102.

[0066] The area surrounded by the valve disc 105, the chamber-forming disc 106, the spacer 107, and the passage disc 108 forms an inner volume chamber 173 (volume chamber) which communicates with the side of the inner passage hole 57 of the recessed portion 65 of the piston 15 relative to the seat disc 111 and the valve plate portion 161 of the valve disc 112, and with a common passage 172 which includes the inner passage hole 57, via passages within the through hole 145 of the passage disc 108, the through hole 148 of the passage disc 109, the through hole 152 of the orifice disc 110, the through hole 157 of the seat disc 111, and the notch 163 of the valve disc 112.

[0067] When the outer periphery of the chamber-forming disc 106 deforms axially toward the passage disc 108 together with the outer periphery of the valve disc 105 so as to shorten the seal portion 136 in the axial direction, the volume of the outer volume chamber 171 increases and the volume of the inner volume chamber 173 decreases. The portion of the recess 65 of the piston 15 between the orifice disc 102 and the outer seat portion 54 in the axial direction, the orifice disc 102, the disc 103, the spring disc 104, the valve disc 105, the chamber-forming disc 106, the spacer 107, the passage disc 108, the passage disc 109, the orifice disc 110, and the seat disc 111 constitute a volume-changing mechanism 175 that changes the volumes of the outer volume chamber 171 and the inner volume chamber 173. Thus, the volume-changing mechanism 175 includes the disc 135 to which the rubber seal portion 136 is baked.

[0068] The valve disc 112 closes the through hole 156 of the seat disc 111 when the valve plate portion 161 is seated on the seat disc 111. The valve disc 112 opens the through hole 156 of the seat disc 111 when the valve plate portion 161 is lifted off from the seat disc 111. When the pressure of the oil L introduced from the first chamber 21 into the outer volume chamber 171 via the first orifice 121 of the orifice disc 102 becomes higher than the pressure of the common passage 172 by a predetermined value or more, the valve plate portion 161 of the valve disc 112 elastically deforms the spring plate portion 162 while moving away from the seat disc 111 in the axial direction, causing the oil L from the outer volume chamber 171 to flow into the common passage 172 via the second orifice 151 of the orifice disc 110 and the passage in the through hole 156 of the seat disc 111, generating a damping force. The valve disc 112 and the seat disc 111 constitute an extension-side damping force generating mechanism 181 that generates a damping force while causing oil liquid L to flow from the first chamber 21 to the common passage 172 via the second orifice 151 of the orifice disc 110 as the piston 15 moves during the extension stroke. The second orifice 151 of the orifice disc 110 is provided in series on the first chamber 21 side of the extension-side damping force generating mechanism 181. An orifice disc 102, in which a first orifice 121 is formed, is provided in a position facing the first chamber 21, closer to the first chamber 21 than the extension-side damping force generating mechanism 181 of the second passage hole 68.

[0069] The extension side damping force generating mechanism 181 is disposed inside the piston 15. That is, the extension side damping force generating mechanism 181 is disposed within the axial range of the piston 15 and within the radial range of the piston 15. In the flow path connecting the first chamber 21 and the common passage 172, the volume variable mechanism 175, which changes the volumes of the outer volume chamber 171 and the inner volume chamber 173, no longer functions as an accumulator when the extension side damping force generating mechanism 181 opens, bringing the outer volume chamber 171 and the inner volume chamber 173 into communication with each other. For this reason, in the flow path connecting the first chamber 21 and the common passage 172, the outer volume chamber 171, the inner volume chamber 173, and the volume variable mechanism 175, which changes the volumes of the outer volume chamber 171 and the inner volume chamber 173, are provided in parallel with the extension side damping force generating mechanism 181. An orifice disk 102 is provided in the outer volume chamber 171 at a position facing the first chamber 21.

[0070] The valve disc 105 is entirely seated on the disc 135 of the chamber-forming disc 106, thereby closing the through-hole 141 of the disc 135. The valve disc 105 opens the through-hole 141 of the disc 135 when the outer peripheral side thereof leaves the disc 135 of the chamber-forming disc 106. When the pressure of the oil liquid L in the inner volume chamber 173 becomes higher than the pressure in the outer volume chamber 171 by a predetermined value or more, the outer peripheral side of the valve disc 105 elastically deforms the spring plate portion 126 of the spring disc 104 and moves away from the disc 135 of the chamber-forming disc 106 in the axial direction, thereby connecting the inner volume chamber 173 and the outer volume chamber 171 via the passage in the through-hole 141 of the disc 135. When the pressure of the oil liquid L in the outer volume chamber 171 is equal to or higher than the pressure in the inner volume chamber 173, the valve disc 105 does not connect the outer volume chamber 171 and the inner volume chamber 173. The valve disc 105, the spring disc 104, and the disc 135 of the chamber forming disc 106 constitute a check valve 185 that restricts the flow of oil liquid L from the outer volume chamber 171 to the inner volume chamber 173, while allowing the flow of oil liquid L from the inner volume chamber 173 to the outer volume chamber 171.

[0071] When the check valve 185 opens, the inner volume chamber 173 and the outer volume chamber 171 are connected to each other and the variable volume mechanism 175 no longer functions as an accumulator, so the check valve 185 (upper) and variable volume mechanism 175 are provided in parallel on the flow path connecting the first chamber 21 and the common passage 172. The check valve 185 and variable volume mechanism 175 are provided in parallel with the second orifice 151 of the orifice disc 110 and the extension-side damping force generating mechanism 181 on the flow path connecting the first chamber 21 and the common passage 172.

[0072] As shown in FIGS. 6 and 7 , the shock absorber 1 is disposed between a lower portion of the outer passage forming portion 44 and a lower portion of the boss portion 42 in the radial direction of the piston 15, and between the piston 15 and the main valve 82 in the axial direction of the piston 15, and is provided with, in order from the main valve 82 side in the axial direction, a plurality of disks 201 similar to the disks 101, a single orifice disk 202 (first orifice member) similar to the orifice disk 102, a single disk 203 similar to the disk 103, and a single spring disk 204 similar to the spring disk 104. It has one valve disc 205 similar to the valve disc 105, one chamber forming disc 206 similar to the chamber forming disc 106, one spacer 207 similar to the spacer 107, one passage disc 208 similar to the passage disc 108, one passage disc 209 similar to the passage disc 109, one orifice disc 210 similar to the orifice disc 110, one seat disc 211 similar to the seat disc 111, and one valve disc 212 similar to the valve disc 112.

[0073] The plurality of disks 201, orifice disk 202, disk 203, spring disk 204, valve disk 205, chamber forming disk 206, spacer 207, passage disk 208, passage disk 209, orifice disk 210, seat disk 211 and valve disk 212 are arranged symmetrically with the plurality of disks 101, orifice disk 102, disk 103, spring disk 104, valve disk 105, chamber forming disk 106, spacer 107, passage disk 108, passage disk 109, orifice disk 110, seat disk 111 and valve disk 112 in the axial direction of piston 15.

[0074] The plurality of disks 201, orifice disk 202, disk 203, spring disk 204, valve disk 205, chamber forming disk 206, spacer 207, passage disk 208, passage disk 209, orifice disk 210 and seat disk 211 are all annular, and a portion below the inner passage forming portion 43 of the boss portion 42 of the piston 15 is fitted into the radially inner side of each of them. The valve disk 212 is annular, and the inner seat portion 53 of the piston 15 is inserted into the radially inner side of each of them.

[0075] The orifice disk 202 is formed with a plurality of first orifices 221 similar to the plurality of first orifices 121 of the orifice disk 102. The orifice disk 202 faces the second chamber 22, and the first orifices 221 communicate with the second chamber 22 via a plurality of passage grooves 72 of the piston 15.

[0076] The spring disc 204 has a base plate portion 225 similar to the base plate portion 125 of the spring disc 104, and a plurality of spring plate portions 126 similar to the plurality of spring plate portions 126 of the spring disc 104. The spring disc 204 has the boss portion 42 of the piston 15 fitted into the radially inner side of the base plate portion 225.

[0077] The valve disc 205 is formed with a plurality of through holes 231 similar to the plurality of through holes 131 in the valve disc 105 .

[0078] The chamber-forming disk 206 has a disk 235 similar to the disk 135 of the chamber-forming disk 106, and a seal portion 236 similar to the seal portion 136 of the chamber-forming disk 106. The disk 235 has a plurality of through holes 241 formed therein similar to the plurality of through holes 141 of the disk 135.

[0079] The passageway disc 208 has a plurality of through holes 245 formed therein, similar to the plurality of through holes 145 in the passageway disc 108 .

[0080] The passage disc 209 has a plurality of through holes 248 formed therein, similar to the plurality of through holes 148 in the passage disc 109 .

[0081] The orifice disk 210 is formed with a plurality of second orifices 251 similar to the plurality of second orifices 151 of the orifice disk 110 , and a plurality of through holes 252 similar to the plurality of through holes 152 of the orifice disk 110 .

[0082] The sheet disc 211 has a plurality of through holes 256 similar to the plurality of through holes 156 of the sheet disc 111 and a plurality of through holes 257 similar to the plurality of through holes 157 of the sheet disc 111 formed therein.

[0083] The valve disc 212 has a valve plate portion 261 similar to the valve plate portion 161 of the valve disc 112, and a plurality of spring plate portions 262 similar to the plurality of spring plate portions 162 of the valve disc 112. The valve plate portion 261 has a plurality of notches 263 formed therein similar to the plurality of notches 163 of the valve disc 112.

[0084] At least the inner circumferential sides of the plurality of discs 201, orifice disc 202, disc 203, spring disc 204, valve disc 205, chamber forming disc 206, spacer 207, passage disc 208, passage disc 209, orifice disc 210 and seat disc 211, together with the main valve 82, are clamped in the axial direction to the disc 83 and the inner seat portion 53 of the piston 15. At this time, the seat disc 211 abuts against the inner seat portion 53 and the outer seat portion 55 of the piston 15 in the axial direction.

[0085] The valve plate portion 261 abuts against the seat disc 211 to close the through hole 256 of the seat disc 211. When the valve plate portion 261 moves away from the seat disc 211 in the axial direction of the seat disc 211, the valve plate portion 261 opens the through hole 256 of the seat disc 211.

[0086] The plurality of spring plate portions 262 abut against the bottom surface of the recessed portion 66 of the piston 15 and urge the valve plate portion 261 in a direction in which it abuts against the seat disc 211 and closes the through hole 256 of the seat disc 211 .

[0087] Between the axial orifice disc 202 and the outer seat portion 55 in the recessed portion 66 of the piston 15, and between the radial outer passage forming portion 44 and the disc 203, the spring disc 204, the valve disc 205, the chamber forming disc 206, the passage disc 208, the passage disc 209, the orifice disc 210 and the seat disc 211, there is formed an outer volume chamber 271 (volume chamber) which is connected to the second chamber 22 via the first orifice 221 of the orifice disc 202.

[0088] The area surrounded by the valve disc 205, the chamber-forming disc 206, the spacer 207, and the passage disc 208 forms an inner volume chamber 273 (volume chamber) which communicates with the side of the inner passage hole 57 of the recessed portion 66 of the piston 15 relative to the seat disc 211 and the valve plate portion 261 of the valve disc 212 and with the common passage 172 which includes the inner passage hole 57, via passages within the through hole 245 of the passage disc 208, the through hole 248 of the passage disc 209, the through hole 252 of the orifice disc 210, the through hole 257 of the seat disc 211, and the notch 263 of the valve disc 212.

[0089] When the outer periphery of the chamber-forming disc 206 deforms axially toward the passage disc 208 together with the outer periphery of the valve disc 205 so as to shorten the seal portion 236 in the axial direction, the volume of the outer volume chamber 271 increases and the volume of the inner volume chamber 273 decreases. The portion of the recess 66 of the piston 15 between the orifice disc 202 and the outer seat portion 55 in the axial direction, the orifice disc 202, the disc 203, the spring disc 204, the valve disc 205, the chamber-forming disc 206, the spacer 207, the passage disc 208, the passage disc 209, the orifice disc 210, and the seat disc 211 constitute a volume-changing mechanism 275 that changes the volumes of the outer volume chamber 271 and the inner volume chamber 273. Thus, the volume-changing mechanism 275 includes the disc 235 to which the rubber seal portion 236 is baked.

[0090] The valve disc 212 closes the through hole 256 of the seat disc 211 when the valve plate portion 261 is seated on the seat disc 211. The valve disc 212 opens the through hole 256 of the seat disc 211 when the valve plate portion 261 is lifted off the seat disc 211. When the pressure of the oil L introduced from the second chamber 22 into the outer volume chamber 271 via the first orifice 221 of the orifice disc 202 becomes higher than the pressure of the common passage 172 by a predetermined value or more, the valve plate portion 261 of the valve disc 212 elastically deforms the spring plate portion 262 while moving away from the seat disc 211 in the axial direction, causing the oil L from the outer volume chamber 271 to flow into the common passage 172 via the second orifice 251 of the orifice disc 210 and the through hole 256 of the seat disc 211, generating a damping force. The valve disc 212 and the seat disc 211 constitute a compression damping force generating mechanism 281 that generates a damping force while causing oil liquid L to flow from the second chamber 22 to the common passage 172 via the second orifice 251 of the orifice disc 210 as the piston 15 moves during the compression stroke. The second orifice 251 of the orifice disc 210 is provided in series on the second chamber 22 side of the compression damping force generating mechanism 281. An orifice disc 202, in which a first orifice 221 is formed, is provided in a position facing the second chamber 22, closer to the second chamber 22 than the compression damping force generating mechanism 281 of the second passage hole 68.

[0091] The compression side damping force generating mechanism 281 is disposed inside the piston 15. That is, the compression side damping force generating mechanism 281 is disposed within the axial range of the piston 15 and within the radial range of the piston 15. In the flow path connecting the second chamber 22 and the common passage 172, the volume variable mechanism 275, which changes the volumes of the outer volume chamber 271 and the inner volume chamber 273, no longer functions as an accumulator when the compression side damping force generating mechanism 281 opens, bringing the outer volume chamber 271 and the inner volume chamber 273 into communication with each other. For this reason, in the flow path connecting the second chamber 22 and the common passage 172, the outer volume chamber 271 and the inner volume chamber 273, and the volume variable mechanism 275, which changes the volumes of the outer volume chamber 271 and the inner volume chamber 273, are provided in parallel with the compression side damping force generating mechanism 281. An orifice disk 202 is provided in the outer volume chamber 271 at a position facing the second chamber 22.

[0092] The valve disc 205 is entirely seated on the disc 235 of the chamber-forming disc 206, thereby closing the through-hole 241 of the disc 235. The valve disc 205 opens the through-hole 241 of the disc 235 when the outer peripheral side thereof leaves the disc 235 of the chamber-forming disc 206. When the pressure of the oil liquid L in the inner volume chamber 273 becomes higher than the pressure in the outer volume chamber 271 by a predetermined value or more, the outer peripheral side of the valve disc 205 elastically deforms the spring plate portion 226 of the spring disc 204 and moves away from the disc 235 of the chamber-forming disc 206 in the axial direction, thereby connecting the inner volume chamber 273 and the outer volume chamber 271 via the passage in the through-hole 241 of the disc 235. When the pressure of the oil liquid L in the outer volume chamber 271 is equal to or higher than the pressure in the inner volume chamber 273, the valve disc 205 does not connect the outer volume chamber 271 and the inner volume chamber 273. The valve disc 205, the spring disc 204, and the disc 235 of the chamber forming disc 206 constitute a check valve 285 that restricts the flow of oil liquid L from the outer volume chamber 271 to the inner volume chamber 273, while allowing the flow of oil liquid L from the inner volume chamber 273 to the outer volume chamber 271.

[0093] When the check valve 285 opens, the inner volume chamber 273 and the outer volume chamber 271 are connected to each other and the volume variable mechanism 275 no longer functions as an accumulator, and therefore the check valve 285 and the volume variable mechanism 275 are provided in parallel on the flow path connecting the second chamber 22 and the common passage 172. The check valve 285 and the volume variable mechanism 275 are provided in parallel with the second orifice 251 of the orifice disc 210 and the compression-side damping force generating mechanism 281 on the flow path connecting the second chamber 22 and the common passage 172.

[0094] 4 , the pressure in the first chamber 21 becomes higher than the pressure in the common passage 172, which has substantially the same pressure as the second chamber 22. Then, the oil L in the first chamber 21 flows through the passages in the plurality of passage grooves 71 of the piston 15, through the first orifice 121 of the orifice disc 102, and into the outer volume chamber 171. Then, the pressure in the outer volume chamber 171 becomes higher than the pressure in the inner volume chamber 173, so that the volume variable mechanism 175 bends toward the passage disc 108 together with the outer circumference of the valve disc 105 while the outer circumferential side of the disc 135 of the chamber forming disc 106 contracts the seal portion 136 in the axial direction, thereby expanding the volume of the outer volume chamber 171 and reducing the volume of the inner volume chamber 173. Then, the oil L that was in the inner volume chamber 173 flows through the passage in the through hole 145 of the passage disk 108, the passage in the through hole 148 of the passage disk 109, the passage in the through hole 152 of the orifice disk 110, the passage in the through hole 157 of the seat disk 111, the passage in the notch 163 of the valve plate portion 161 of the valve disk 112, the common passage 172, the passage in the notch 263 of the valve plate portion 261 of the valve disk 212 shown in FIG. 6, the through hole 257 of the seat disk 211, and so on. 7 , the passage in the through hole 252 of the orifice disk 210, the passage in the through hole 248 of the passage disk 209, and the passage in the through hole 245 of the passage disk 208, then passes through the passage in the through hole 241 of the disk 235 of the chamber-forming disk 206, opens the check valve 285, and flows into the second chamber 22 through the outer volume chamber 271, the first orifice 221 of the orifice disk 202, and the passage in the passage groove 72 of the piston 15 shown in FIG.

[0095] Furthermore, during the extension stroke, the first chamber 21 shown in FIG. 4 becomes higher in pressure than the second chamber 22, i.e., the common passage 172, which has approximately the same pressure as the second chamber 22, and the oil L in the first chamber 21 flows through the first orifice 121 of the orifice disc 102 into the outer volume chamber 171. When the pressure in the outer volume chamber 171 becomes higher than the common passage 172 by a predetermined value or more, the extension side damping force generating mechanism 181 opens, and the oil L in the outer volume chamber 171 flows into the common passage 172 via the second orifice 151 of the orifice disc 110, the passage in the through-hole 156 of the seat disc 111, and the passage between the valve plate portion 161 of the valve disc 112 of the extension side damping force generating mechanism 181 that has opened and the seat disc 111. The oil liquid L that has flowed into the common passage 172 passes through the passage in the cutout portion 263 of the valve plate portion 261 of the valve disc 212 shown in FIG. 6 , the passage in the through hole 257 of the seat disc 211, the passage in the through hole 252 of the orifice disc 210, the passage in the through hole 248 of the passage disc 209, and the passage in the through hole 245 of the passage disc 208, enters the inner volume chamber 273, passes through the passage in the through hole 241 of the disc 235 of the chamber forming disc 206, opens the check valve 285, and flows into the second chamber 22 through the outer volume chamber 271, the first orifice 221 of the orifice disc 202, and the passage in the passage groove 72 of the piston 15 shown in FIG. 7.

[0096] As described above, the second passage 301 is formed by a passage including the second passage hole 68, which allows the oil L flowing out from the first chamber 21 of the piston 15 to flow toward the second chamber 22. The second passage 301 includes passages in the plurality of passage grooves 71 of the piston 15 shown in FIG. 4, the first orifice 121 of the orifice disc 102, and the outer volume chamber 171. The second passage 301 also includes the second orifice 151 of the orifice disc 110, a passage in the through-hole 156 of the seat disc 111, and a passage between the seat disc 111 and the valve plate portion 161 of the valve disc 112 of the extension-side damping force generating mechanism 181 in the open valve state. The second passage 301 includes the common passage 172, a passage within the cutout portion 263 of the valve plate portion 261 of the valve disc 212 shown in FIG. 6, a passage within the through hole 257 of the seat disc 211, a passage within the through hole 252 of the orifice disc 210, a passage within the through hole 248 of the passage disc 209, a passage within the through hole 245 of the passage disc 208, the inner volume chamber 273, a passage within the through hole 241 of the disc 235, a passage between the disc 235 and the valve disc 205 of the check valve 285 that is opened, the outer volume chamber 271, the first orifice 221 of the orifice disc 202, and passages within the plurality of passage grooves 72 of the piston 15 shown in FIG. 7.

[0097] The extension side damping force generating mechanism 181 shown in FIG. 4 opens and closes this second passage 301. The extension side damping force generating mechanism 181 is provided in the second passage 301 and opens and closes the second passage 301. When the valve is open, the extension side damping force generating mechanism 181 generates a damping force by allowing hydraulic fluid L to flow from the first chamber 21, which is the upstream side, to the second chamber 22, which is the downstream side. The second passage 301 is a passage through which hydraulic fluid L flows from the first chamber 21, which is the upstream side, to the second chamber 22, which is the downstream side, as the piston 15 moves during the extension stroke. The second passage 301 is provided in parallel with the first passage 86 through which hydraulic fluid L flows from the first chamber 21, which is the upstream side, to the second chamber 22, which is the downstream side, as the piston 15 moves during the extension stroke. Therefore, the extension side damping force generating mechanism 181, which operates during the extension stroke, is provided in parallel with the first damping force generating mechanism 87, shown in FIG. 6, which also operates during the extension stroke. The extension damping force generating mechanism 181 shown in FIG. 4 is disposed inside the piston 15 and in the second passage hole 68 that constitutes a second passage 301 that is parallel to the first passage 86 .

[0098] The main valve 82 of the first damping force generating mechanism 87 (shown in FIG. 6 ) provided in the first extension passage 86 has a higher valve opening pressure than the valve disc 112 of the extension damping force generating mechanism 181 (shown in FIG. 4 ) provided in the second extension passage 301. As a result, the extension damping force generating mechanism 181 operates to generate damping force before the first damping force generating mechanism 87 operates. The extension damping force generating mechanism 181 is provided in the second passage 301 and opens while the first damping force generating mechanism 87 is closed in the low piston speed range. However, when the piston speed is higher than the low piston speed, the extension damping force generating mechanism 181 opens together with the first damping force generating mechanism 87. The volume variable mechanism 175 provided in the second passage 301 operates before the extension damping force generating mechanism 181 and the first damping force generating mechanism 87 operate to change the volumes of the outer volume chamber 171 and the inner volume chamber 173. At this time, the check valve 285 (shown in FIGS. 6 and 7 ) opens.

[0099] 7, the pressure in the second chamber 22 becomes higher than that in the first chamber 21, i.e., the common passage 172, which has substantially the same pressure as that in the first chamber 21. Then, the oil L in the second chamber 22 flows through the passages in the plurality of passage grooves 72 of the piston 15, through the first orifice 221 of the orifice disc 202, and into the outer volume chamber 271. Then, the pressure in the outer volume chamber 271 becomes higher than the pressure in the inner volume chamber 273, so that the volume varying mechanism 275 bends toward the passage disc 208 together with the outer circumference of the valve disc 205 while the outer circumferential side of the disc 235 of the chamber forming disc 206 contracts the seal portion 236 in the axial direction, thereby expanding the volume of the outer volume chamber 271 and reducing the volume of the inner volume chamber 273. Then, the oil L that was in the inner volume chamber 273 flows through the passage in the through hole 245 of the passage disk 208, the passage in the through hole 248 of the passage disk 209, the passage in the through hole 252 of the orifice disk 210, the passage in the through hole 257 of the seat disk 211, the passage in the notch 263 of the valve plate portion 261 of the valve disk 212, the common passage 172, the passage in the notch 163 of the valve plate portion 161 of the valve disk 112 shown in FIG. 5, the through hole 157 of the seat disk 111, and so on. The oil enters the inner volume chamber 173 through the passage in the through hole 152 of the orifice disk 110, the passage in the through hole 148 of the passage disk 109, and the passage in the through hole 145 of the passage disk 108, passes through the passage in the through hole 141 of the disk 135 of the chamber-forming disk 106, opens the check valve 185, and flows into the first chamber 21 through the outer volume chamber 171, the first orifice 121 of the orifice disk 102, and the passage in the passage groove 71 of the piston 15 shown in FIG. 4.

[0100] Furthermore, the second chamber 22 shown in FIG. 7 becomes higher in pressure than the first chamber 21, i.e., the common passage 172, which has approximately the same pressure as the first chamber 21, and the oil L in the second chamber 22 flows through the first orifice 221 of the orifice disc 202 into the outer volume chamber 271. When the pressure in the outer volume chamber 271 becomes higher than the common passage 172 by a predetermined value or more, the compression side damping force generating mechanism 281 opens and the oil L in the outer volume chamber 271 flows into the common passage 172 via the second orifice 251 of the orifice disc 210, the passage in the through hole 256 of the seat disc 211, and the passage between the valve plate portion 261 of the valve disc 212 of the compression side damping force generating mechanism 281 that has opened and the seat disc 211. The oil liquid L that has flowed into the common passage 172 passes through the passage in the cutout portion 163 of the valve plate portion 161 of the valve disc 112 shown in FIG. 5 , the passage in the through hole 157 of the seat disc 111, the passage in the through hole 152 of the orifice disc 110, the passage in the through hole 148 of the passage disc 109, and the passage in the through hole 145 of the passage disc 108, enters the inner volume chamber 173, passes through the passage in the through hole 141 of the disc 135 of the chamber forming disc 106, opens the check valve 185, and flows into the first chamber 21 through the outer volume chamber 171, the first orifice 121 of the orifice disc 102, and the passage in the passage groove 71 of the piston 15 shown in FIG. 4.

[0101] As described above, the second passage 302 is formed by a passage including the second passage hole 68 through which the oil L flowing out of the second chamber 22 shown in Figure 7 in the piston 15 flows toward the first chamber 21. The second passage 302 includes passages in the plurality of passage grooves 72 of the piston 15, the first orifice 221 of the orifice disc 202, and the outer volume chamber 271. The second passage 302 also includes the second orifice 251 of the orifice disc 210, a passage in the through-hole 256 of the seat disc 211, and a passage between the seat disc 211 and the valve plate portion 261 of the valve disc 212 of the compression-side damping force generating mechanism 281 in the open valve state. The second passage 302 includes the common passage 172, a passage within the cutout portion 163 of the valve plate portion 161 of the valve disc 112 shown in FIG. 5, a passage within the through hole 157 of the seat disc 111, a passage within the through hole 152 of the orifice disc 110, a passage within the through hole 148 of the passage disc 109, a passage within the through hole 145 of the passage disc 108, the inner volume chamber 173, a passage within the through hole 141 of the disc 135, a passage between the disc 135 and the valve disc 105 of the check valve 185 that is opened, the outer volume chamber 171, the first orifice 121 of the orifice disc 102, and passages within the plurality of passage grooves 71 of the piston 15 shown in FIG. 4.

[0102] The compression side damping force generating mechanism 281 shown in Figure 7 opens and closes this second passage 302. The compression side damping force generating mechanism 281 is provided in the second passage 302 and opens and closes the second passage 302. When the valve is open, the compression side damping force generating mechanism 281 generates a damping force by allowing hydraulic oil L to flow from the second chamber 22, which is located upstream, to the first chamber 21, which is located downstream. The second passage 302 is a passage through which hydraulic oil L flows from the second chamber 22, which is located upstream, to the first chamber 21, which is located downstream, as the piston 15 moves during the compression stroke. The second passage 302 is provided in parallel with the first passage 96 through which hydraulic oil L flows from the second chamber 22, which is located upstream, to the first chamber 21, which is located downstream, as the piston 15 moves during the compression stroke. Therefore, the compression side damping force generating mechanism 281, which operates during the compression stroke, is provided in parallel with the first damping force generating mechanism 97, shown in Figure 5, which also operates during the compression stroke. The compression-side damping force generating mechanism 281 shown in FIG. 7 is disposed inside the piston 15 and in the second passage hole 68 that constitutes a second passage 302 that is parallel to the first passage 96 .

[0103] The main valve 92 of the first damping force generating mechanism 97 (shown in FIG. 5 ) provided in the first compression passage 96 has a higher valve opening pressure than the valve disc 212 of the compression damping force generating mechanism 281 (shown in FIG. 7 ) provided in the second compression passage 302. As a result, the compression damping force generating mechanism 281 operates to generate damping force before the first damping force generating mechanism 97 operates. The compression damping force generating mechanism 281 is provided in the second passage 302 and opens while the first damping force generating mechanism 97 is closed in the low piston speed range. However, when the piston speed is higher than the low piston speed, the compression damping force generating mechanism 281 opens together with the first damping force generating mechanism 97. The volume variable mechanism 275 provided in the second passage 302 operates before the compression damping force generating mechanism 281 and the first damping force generating mechanism 97 operate to change the volumes of the outer volume chamber 271 and the inner volume chamber 273. At this time, the check valve 185 (shown in FIGS. 4 and 5 ) opens.

[0104] The extension side damping force generating mechanism 181 and the compression side damping force generating mechanism 281 constitute a second damping force generating mechanism 311. The second damping force generating mechanism 311 is disposed inside the piston 15, and is disposed in the second passage hole 68 which constitutes second passages 301, 302 which are parallel to the first passages 86, 96. The second damping force generating mechanism 311 has the extension side damping force generating mechanism 181 disposed on one side of the second passage hole 68, and the compression side damping force generating mechanism 281 disposed on the other side. A common passage 172 is disposed between the extension side damping force generating mechanism 181 and the compression side damping force generating mechanism 281, through which oil L, which is the working fluid for both extension and compression, flows.

[0105] An orifice disk 102 having a first orifice 121 formed therein is provided in a position facing the first chamber 21 on the side of the second damping force generating mechanism 311 in the second passage 301 of the piston 15 that is closer to the first chamber 21 as shown in Fig. 4 than the second damping force generating mechanism 311. Furthermore, an orifice disk 202 having a first orifice 221 formed therein is provided in a position facing the second chamber 22 on the side of the second damping force generating mechanism 311 in the second passage 302 of the piston 15 that is closer to the second chamber 22 as shown in Fig. 7 than the second damping force generating mechanism 311. The second damping force generating mechanism 311, the volume variable mechanism 175 that changes the volumes of the outer volume chamber 171 and the inner volume chamber 173, and the volume variable mechanism 275 that changes the volumes of the outer volume chamber 271 and the inner volume chamber 273 are all disposed radially away from the piston rod 31 of the piston 15.

[0106] A hydraulic circuit diagram of the shock absorber 1 is shown in Figure 8. As shown in Figure 8, the shock absorber 1 is provided with a first passage 86 and a first passage 96 connecting the first chamber 21 and the second chamber 22. A first damping force generating mechanism 87 is provided in the first passage 86. A first damping force generating mechanism 97 is provided in the first passage 96. The shock absorber 1 is provided with a second passage 301 and a second passage 302 connecting the first chamber 21 and the second chamber 22 and arranged in parallel with the first passages 86, 96. A first orifice 121 is provided in the second passage 301 on the first chamber 21 side, and a second orifice 151, an extension-side damping force generating mechanism 181, and a volume variable mechanism 175 are arranged in parallel on the second chamber 22 side of the first orifice 121. The second orifice 151 and the extension side damping force generating mechanism 181 are arranged such that the extension side damping force generating mechanism 181 is closer to the second chamber 22 than the second orifice 151. A common passage 172 is arranged in the second passage 301 closer to the second chamber 22 than the second orifice 151, the extension side damping force generating mechanism 181, and the volume variable mechanism 175, and a check valve 285 is arranged in the common passage 172 on the second chamber 22 side. The second passage 302 is arranged with a first orifice 221 on the second chamber 22 side, and the second orifice 251, the compression side damping force generating mechanism 281, and the volume variable mechanism 275 are arranged in parallel on the first chamber 21 side of the first orifice 221. The second orifice 251 and the compression side damping force generating mechanism 281 are arranged such that the compression side damping force generating mechanism 281 is closer to the first chamber 21 than the second orifice 251. A common passage 172 is provided in the second passage 302 on the first chamber 21 side of the second orifice 251, the compression damping force generating mechanism 281, and the volume variable mechanism 275, and a check valve 185 is provided on the first chamber 21 side of the common passage 172.

[0107] <Operation> {Extension Stroke} During the extension stroke, the piston 15 moves toward the first chamber 21, increasing the pressure in the first chamber 21 and decreasing the pressure in the second chamber 22. During the extension stroke, when the piston speed is in the extremely low speed range equal to or less than the first predetermined value X1, the first damping force generating mechanism 87 remains in a closed state, and the oil L in the first chamber 21 opens the extension damping force generating mechanism 181. Therefore, the oil L in the first chamber 21 flows through the second passage 301, i.e., the passages in the multiple passage grooves 71 of the piston 15, the first orifice 121 of the orifice disc 102, the outer volume chamber 171, the second orifice 151 of the orifice disc 110, the passages in the through-hole 156 of the seat disc 111, the passage between the valve plate portion 161 of the valve disc 112 of the extension side damping force generating mechanism 181 in the open state and the seat disc 111, the common passage 172, and the passages in the notch portion 263 of the valve plate portion 261 of the valve disc 212. The fluid flows to the second chamber 22 via the passage within the through hole 257 of the seat disc 211, the passage within the through hole 252 of the orifice disc 210, the passage within the through hole 248 of the passage disc 209, the passage within the through hole 245 of the passage disc 208, the inner volume chamber 273, the passage within the through hole 241 of the disc 235, the passage between the disc 235 of the opened check valve 285 and the valve disc 205, the outer volume chamber 271, the first orifice 221 of the orifice disc 202, and the passages within the plurality of passage grooves 72 of the piston 15. As a result, during the extension stroke in the extremely low speed range where the piston speed is equal to or less than the first predetermined value X1, the extension-side damping force generating mechanism 181 provides a damping force with a valve characteristic (a characteristic in which the damping force is approximately proportional to the piston speed).

[0108] At this time, the oil liquid L from the first chamber 21 that has entered the outer volume chamber 171 increases the pressure in the outer volume chamber 171. Therefore, in the volume variable mechanism 175, the outer peripheral side of the disk 135 of the chamber forming disk 106 flexes toward the passage disk 108 together with the outer peripheral side of the valve disk 105 while contracting the seal portion 136 in the axial direction, thereby expanding the volume of the outer volume chamber 171 and reducing the volume of the inner volume chamber 173. Then, the oil L in the inner volume chamber 173 flows through the passage in the through hole 145 of the passage disk 108, the passage in the through hole 148 of the passage disk 109, the passage in the through hole 152 of the orifice disk 110, the passage in the through hole 157 of the seat disk 111, the passage in the notch 163 of the valve plate portion 161 of the valve disk 112, the common passage 172, the passage in the notch 263 of the valve plate portion 261 of the valve disk 212, the passage in the through hole 257 of the seat disk 211, and the orifice The fluid flows to the second chamber 22 via the passage in the through-hole 252 of the orifice disk 210, the passage in the through-hole 248 of the passage disk 209, the passage in the through-hole 245 of the passage disk 208, the inner volume chamber 273, the passage in the through-hole 241 of the disk 235 of the chamber-forming disk 206, the passage between the disk 235 of the check valve 285 that is opened and the valve disk 205, the outer volume chamber 271, the first orifice 221 of the orifice disk 202, and the passage in the passage groove 72 of the piston 15. This allows the volume of the outer volume chamber 171 to expand smoothly.

[0109] Here, during the extension stroke in the extremely low speed region when a low frequency input (large amplitude vibration) is applied, which is the frequency of the axial movement of the piston 15, the amount of oil L flowing from the first chamber 21 into the outer volume chamber 171 increases, so that in the volume variable mechanism 175, the outer periphery of the disc 135 of the chamber forming disc 106 immediately flexes significantly toward the passage disc 108 together with the outer periphery of the valve disc 105, causing the seal portion 136 to contract in the axial direction, expanding the volume of the outer volume chamber 171 and reducing the volume of the inner volume chamber 173. Then, the volume variable mechanism 175 enters a state in which the volume expansion of the outer volume chamber 171 is suppressed, so the outer volume chamber 171 immediately rises in pressure, and the extension-side damping force generating mechanism 181 immediately opens to generate a damping force with valve characteristics.

[0110] During the extension stroke in the normal speed range where the piston speed is greater than the first predetermined value X1, the first damping force generating mechanism 87 opens while the extension side damping force generating mechanism 181 remains open. That is, as described above, the hydraulic oil L flows from the first chamber 21 to the second chamber 22 through the second passage 301, but at this time, the flow of the hydraulic oil L is throttled by the first orifice 121 provided in the second passage 301 upstream of the extension side damping force generating mechanism 181, so that the pressure applied to the main valve 82 in the first passage 86 increases, the pressure difference increases, and the main valve 82 lifts off the outer passage seat 75, causing the hydraulic oil L to flow from the first chamber 21 to the second chamber 22 through the extension side first passage 86. Therefore, the oil L in the first chamber 21 flows into the second chamber 22 through the first passage 86 when the first damping force generating mechanism 87 is open, i.e., through the passages in the multiple passage grooves 71 of the piston 15, the passages in the multiple first passage holes 61 of the piston 15, and the passage between the open main valve 82 and the outer passage seat portion 75.

[0111] During the extension stroke in the extremely low speed region when a high frequency input (small amplitude vibration) is applied to the shock absorber 1 at a piston frequency higher than that at the time of the low frequency input described above, the amount of oil liquid L flowing from the first chamber 21 through the passage in the passage groove 71 of the piston 15 and the first orifice 121 of the orifice disc 102 into the outer volume chamber 171 is small. For this reason, in the volume variable mechanism 175, the outer circumferential side of the disc 135 of the chamber forming disc 106 flexes toward the passage disc 108 together with the outer circumferential side of the valve disc 105 while causing the seal portion 136 to contract in the axial direction, and the amount of flexure of the chamber forming disc 106 and the valve disc 105 can absorb the volume of oil liquid L flowing into the outer volume chamber 171.

[0112] {Compression Stroke} During the compression stroke, the piston 15 moves toward the second chamber 22, increasing the pressure in the second chamber 22 and decreasing the pressure in the first chamber 21. During the compression stroke in the extremely low speed region where the piston speed is equal to or less than the second predetermined value X2, the first damping force generating mechanism 97 remains in a closed state, and the oil L in the second chamber 22 opens the compression-side damping force generating mechanism 281. Therefore, the oil L in the second chamber 22 flows through the second passage 302, i.e., the passages in the plurality of passage grooves 72 of the piston 15, the first orifice 221 of the orifice disc 202, the outer volume chamber 271, the second orifice 251 of the orifice disc 210, the passages in the through-hole 256 of the seat disc 211, the passages in the through-hole 256 of the seat disc 211, the passage between the valve plate portion 261 of the valve disc 212 of the compression-side damping force generating mechanism 281 in the open valve state and the seat disc 211, the common passage 172, and the valve plate portion 161 of the valve disc 112. The fluid flows to the first chamber 21 via the passage within the cutout 163, the passage within the through hole 157 of the seat disk 111, the passage within the through hole 152 of the orifice disk 110, the passage within the through hole 148 of the passage disk 109, the passage within the through hole 145 of the passage disk 108, the inner volume chamber 173, the passage within the through hole 141 of the disk 135, the passage between the disk 135 of the open check valve 185 and the valve disk 105, the outer volume chamber 171, the first orifice 121 of the orifice disk 102, and the passages within the plurality of passage grooves 71 of the piston 15. As a result, during the compression stroke in the extremely low speed range where the piston speed is equal to or less than the second predetermined value X2, the compression-side damping force generating mechanism 281 provides a damping force with valve characteristics.

[0113] At this time, the oil liquid L in the second chamber 22 that has entered the outer volume chamber 271 increases the pressure in the outer volume chamber 271. Therefore, in the volume variable mechanism 275, the outer peripheral side of the disk 235 of the chamber forming disk 206 flexes toward the passage disk 208 together with the outer peripheral side of the valve disk 205 while contracting the seal portion 236 in the axial direction, thereby expanding the volume of the outer volume chamber 271 and reducing the volume of the inner volume chamber 273. Then, the oil L in the inner volume chamber 273 flows through the passage in the through hole 245 of the passage disk 208, the passage in the through hole 248 of the passage disk 209, the passage in the through hole 252 of the orifice disk 210, the passage in the through hole 257 of the seat disk 211, the passage in the notch 263 of the valve plate portion 261 of the valve disk 212, the common passage 172, the passage in the notch 163 of the valve plate portion 161 of the valve disk 112, the passage in the through hole 157 of the seat disk 111, and the orifice The air flows to the first chamber 21 via the passage in the through-hole 152 of the orifice disk 110, the passage in the through-hole 148 of the passage disk 109, the passage in the through-hole 145 of the passage disk 108, the inner volume chamber 173, the passage in the through-hole 141 of the disk 135 of the chamber-forming disk 106, the passage between the disk 135 of the check valve 185 that is opened and the valve disk 105, the outer volume chamber 171, the first orifice 121 of the orifice disk 102, and the passage in the passage groove 71 of the piston 15. This allows the volume of the outer volume chamber 271 to expand smoothly.

[0114] Here, during the compression stroke in the extremely low speed range when a low frequency input (large amplitude vibration) is applied, which is the frequency of the axial movement of the piston 15, the amount of oil L flowing from the second chamber 22 into the outer volume chamber 271 increases, so that in the volume variable mechanism 275, the outer circumferential side of the disc 235 of the chamber forming disc 206 immediately flexes significantly toward the passage disc 208 together with the outer circumferential side of the valve disc 205 while causing the seal portion 236 to contract in the axial direction, thereby expanding the volume of the outer volume chamber 271 and reducing the volume of the inner volume chamber 273. Then, the volume variable mechanism 275 is subsequently placed in a state in which the volume expansion of the outer volume chamber 271 is suppressed, so that the outer volume chamber 271 is immediately pressurized, and the compression-side damping force generating mechanism 281 immediately opens to generate a damping force with valve characteristics.

[0115] During the compression stroke in the normal speed range where the piston speed is greater than the second predetermined value X2, the first damping force generating mechanism 97 opens while the compression side damping force generating mechanism 281 remains open. That is, as described above, the hydraulic oil L flows from the second chamber 22 to the first chamber 21 through the second passage 302, but at this time, the flow of the hydraulic oil L is throttled by the first orifice 221 provided in the second passage 302 upstream of the compression side damping force generating mechanism 281, so that the pressure applied to the main valve 92 in the first passage 96 increases, the pressure difference increases, and the main valve 92 lifts off the outer passage seat 76, causing the hydraulic oil L to flow from the second chamber 22 to the first chamber 21 through the compression side first passage 96. Therefore, the oil L in the second chamber 22 flows into the first chamber 21 through the first passage 96 when the first damping force generating mechanism 97 is open, i.e., through the passages in the multiple passage grooves 72 of the piston 15, the passages in the multiple first passage holes 62, and the passage between the open main valve 92 and the outer passage seat portion 76.

[0116] During the compression stroke in the extremely low speed region when a high frequency input (small amplitude vibration) is applied to the shock absorber 1 at a piston frequency higher than that at the time of the low frequency input described above, the amount of oil liquid L flowing from the second chamber 22 through the passage in the passage groove 72 of the piston 15 and the first orifice 221 of the orifice disc 202 into the outer volume chamber 271 is small. For this reason, in the volume variable mechanism 275, the outer circumferential side of the disc 235 of the chamber forming disc 206 flexes toward the passage disc 208 together with the outer circumferential side of the valve disc 205 while causing the seal portion 236 to contract in the axial direction, but the amount of flexure of the chamber forming disc 206 and the valve disc 205 is small, and the volume of oil liquid L flowing into the outer volume chamber 271 can be absorbed by the amount of flexure of the chamber forming disc 206 and the valve disc 205, thereby reducing the pressure rise in the outer volume chamber 271. Therefore, when the damping force rises in the extremely low speed region where the piston speed is below the second predetermined value X2, it is possible to achieve the same state as if the chamber forming disc 206 and valve disc 205 were not present and the outer volume chamber 271 were connected to the first chamber 21.

[0117] The reference example in the aforementioned Patent Document 1 discloses a shock absorber in which two valves that open during the same stroke are arranged in parallel. This shock absorber includes a piston slidably mounted within a cylinder and dividing the cylinder into one side chamber and another side chamber. The piston is provided with a first passageway connecting these chambers and a first damping force generating mechanism that is provided in the first passageway and generates a damping force. A separate member attached to the piston is provided with a second passageway connecting the one side chamber and the other side chamber, and a second damping force generating mechanism that is provided in the second passageway and generates a damping force. This results in an increase in the size of the structure around the piston.

[0118] In the shock absorber 1 of the first embodiment, the piston 15 is slidably fitted in the cylinder 11 and divides the interior of the cylinder 11 into a first chamber 21 and a second chamber 22. The piston 15 is provided with second passages 301, 302 through which hydraulic fluid L flows from the upstream chamber of the first chamber 21 and the second chamber 22 in the cylinder 11 to the downstream chamber of the first chamber 21 and the second chamber 22 as the piston 15 moves. The second damping force generating mechanism 311 is disposed in a second passage hole 68 that constitutes the second passages 301, 302 inside the piston 15. This allows the shock absorber 1 to have a configuration around the piston 15 that is slidably fitted in the cylinder 11 and divides the interior of the cylinder 11 into the first chamber 21 and the second chamber 22, which can be made smaller and lighter, particularly in the axial direction. This allows for a reduction in the size and weight of the piston rod 31 to which the piston 15 is attached, as well as the assembly including the piston 15. Furthermore, in the shock absorber 1, it is not necessary to provide a flow path in the piston rod 31 that connects the first chamber 21 and the second chamber 22, which facilitates the manufacture of the piston rod 31. Furthermore, in the shock absorber 1, the second damping force generating mechanism 311 can be incorporated into the piston 15 in advance, which facilitates the assembly of the second damping force generating mechanism 311. It is also possible to provide the piston 15 not in the piston rod 31 but in a tank as a cylinder separate from the cylinder 11, for example.

[0119] Furthermore, in the shock absorber 1, the second damping force generating mechanism 311 has the extension side damping force generating mechanism 181 disposed on one side of the second passage hole 68 and the compression side damping force generating mechanism 281 disposed on the other side, so that the damping force characteristics of the extension side damping force generating mechanism 181 and the compression side damping force generating mechanism 281 can be set independently, improving tunability. Therefore, for example, it is possible to set the damping force characteristics of the extension side and the compression side separately for each vehicle model. Note that it is also possible to provide only one of the extension side damping force generating mechanism 181 and the compression side damping force generating mechanism 281 in the second damping force generating mechanism 311.

[0120] In addition, the shock absorber 1 has a common passage 172 between the extension side damping force generating mechanism 181 and the compression side damping force generating mechanism 281, through which the working fluid flows during both the extension stroke and the compression stroke, thereby simplifying the configuration.

[0121] Furthermore, the shock absorber 1 is provided with the outer volume chamber 171 and the inner volume chamber 173, and a volume variable mechanism 175 that changes the volumes of the outer volume chamber 171 and the inner volume chamber 173, in parallel with the second damping force generating mechanism 311, and is also provided with the outer volume chamber 271 and the inner volume chamber 273, and a volume variable mechanism 275 that changes the volumes of the outer volume chamber 271 and the inner volume chamber 273, in parallel with the second damping force generating mechanism 311. Therefore, the damping force characteristics can be set independently for the volume variable mechanism 175 that changes the volumes of the outer volume chamber 171 and the inner volume chamber 173 and the volume variable mechanism 275 that changes the volumes of the outer volume chamber 271 and the inner volume chamber 273, which further improves the degree of freedom in setting the damping force characteristics and further improves tunability. In addition, in the shock absorber 1, it is possible to provide only one of the outer volume chamber 171, inner volume chamber 173 and volume variable mechanism 175, or the outer volume chamber 271, inner volume chamber 273 and volume variable mechanism 275, or it is also possible to provide neither.

[0122] In addition, the shock absorber 1 has the outer volume chamber 171 and the inner volume chamber 173, the volume variable mechanism 175 that changes the volume of the outer volume chamber 171 and the inner volume chamber 173, the outer volume chamber 271 and the inner volume chamber 273, and the volume variable mechanism 275 that changes the volume of the outer volume chamber 271 and the inner volume chamber 273 located inside the piston 15, so it can be made smaller and lighter, including these.

[0123] Furthermore, in the shock absorber 1, the volume variable mechanism 175 has the disk 135 with rubber baked on it, so the outer volume chamber 171 and the inner volume chamber 173 can be well separated, resulting in stable performance. Furthermore, the volume variable mechanism 275 has the disk 235 with rubber baked on it, so the outer volume chamber 271 and the inner volume chamber 273 can be well separated, resulting in stable performance.

[0124] Furthermore, in the shock absorber 1, the check valve 185 is provided in the volume variable mechanism 175, which allows the oil liquid L to flow from the second chamber 22 to the first chamber 21 while restricting the flow of the oil liquid L from the first chamber 21 to the second chamber 22. Therefore, when the compression-side damping force generating mechanism 281 is open, the oil liquid L can flow smoothly from the second chamber 22 to the first chamber 21 via the check valve 185. In the shock absorber 1, the check valve 285 is provided in the volume variable mechanism 275, which allows the oil liquid L to flow from the first chamber 21 to the second chamber 22 while restricting the flow of the oil liquid L from the second chamber 22 to the first chamber 21. Therefore, when the extension-side damping force generating mechanism 181 is open, the oil liquid L can flow smoothly from the first chamber 21 to the second chamber 22 via the check valve 285.

[0125] Furthermore, the shock absorber 1 is provided with an orifice disk 102 having a first orifice 121 formed therein at a position facing the first chamber 21 and closer to the first chamber 21 than the second damping force generating mechanism 311 in the second passage 301. This makes it possible to prevent an excessive flow of oil L from the first chamber 21 from flowing into the second damping force generating mechanism 311, thereby improving the durability of the second damping force generating mechanism 311. Furthermore, an orifice disk 202 having a first orifice 221 formed therein is provided with a position facing the second chamber 22 and closer to the second chamber 22 than the second damping force generating mechanism 311 in the second passage 302. This makes it possible to prevent an excessive flow of oil L from the second chamber 22 from flowing into the second damping force generating mechanism 311, thereby improving the durability of the second damping force generating mechanism 311. It is also possible to provide only one of the orifice disk 102 in which the first orifice 121 is formed and the orifice disk 202 in which the first orifice 221 is formed, and it is also possible not to provide both the first orifice 121 and the first orifice 221, as in the hydraulic circuit diagram shown in Figure 9.

[0126] 10, it is also possible to provide an intermediate chamber 272 instead of the common passage 172 without providing both the first orifice 121 and the first orifice 221. It is also possible to provide at least one of the first orifice 121 and the first orifice 221, and provide the intermediate chamber 272 instead of the common passage 172.

[0127] Furthermore, the shock absorber 1 can have a compact and simplified overall configuration because the first passage 86 and the first damping force generating mechanism 87, and the first passage 96 and the first damping force generating mechanism 97 are provided in the piston 15. Note that the first passage 86 and the first damping force generating mechanism 87, and the first passage 96 and the first damping force generating mechanism 97 can also be provided in separate positions rather than in the piston 15.

[0128] Furthermore, in the shock absorber 1, the second damping force generating mechanism 311, the volume variable mechanism 175 that changes the volumes of the outer volume chamber 171 and the inner volume chamber 173, and the volume variable mechanism 275 that changes the volumes of the outer volume chamber 271 and the inner volume chamber 273 are arranged at positions radially spaced apart from the piston rod 31 of the piston 15, so that the piston 15 can be assembled to the piston rod 31 with these mechanisms pre-assembled to the piston 15. This makes it easy to assemble the second damping force generating mechanism 311, the volume variable mechanism 175, and the volume variable mechanism 275 to the piston rod 31.

[0129] Second Embodiment A second embodiment will be described with reference to Figures 11 to 16, focusing on differences from the first embodiment. Note that parts similar to those in the first embodiment are designated by the same names and reference numerals.

[0130] In the shock absorber 1A of the second embodiment, as shown in Figures 11 and 12, instead of the chamber forming disk 106 of the shock absorber 1, a disk 135 of the chamber forming disk 106 and a plate valve 106A which is a separate disc spring are provided.

[0131] In the shock absorber 1A, a disk 135 is provided between the axial valve disk 105 and the spacer 107, and a plate valve 106A is provided between the axial spacer 107 and the passage disk 108.

[0132] The plate valve 106A has an annular shape, and a portion of the boss 42 of the piston 15 above the inner passage forming portion 43 is fitted into the radially inner portion of the plate valve 106A. The plate valve 106A is made of metal and formed by press molding. As shown in Figures 13 and 14, the plate valve 106A has a perforated circular flat plate-like base portion 351 and a tapered cylindrical spring plate portion 136A that widens in diameter from the outer peripheral edge of the base portion 351 and expands to one axial side.

[0133] The plate valve 106A has a base plate portion 351 fitted radially inward above the inner passage forming portion 43 of the boss portion 42 of the piston 15. The outer diameter of the base plate portion 351 is smaller than the outer diameter of the passage disk 108. A through hole 352 is formed in the base plate portion 351 at a radially intermediate position between the inner peripheral portion and the outer peripheral portion, penetrating the base plate portion 351 in the axial direction, i.e., the thickness direction. A plurality of through holes 352 are formed in the base plate portion 351 at equal intervals in the circumferential direction of the base plate portion 351.

[0134] The tapered cylindrical spring plate portion 136A has an outer diameter smaller than that of the disk 135. In the plate valve 106A, the height of the spring plate portion 136A protruding in the axial direction from the base plate portion 351 in the natural state before assembly is longer than the axial length of the spacer 107.

[0135] The plate valve 106A has a base plate portion 351 sandwiched between the spacer 107 and the passage disk 108. In this state, the through holes 352 of the base plate portion 351 communicate with the through holes 145 of the passage disk 108. The spring plate portion 136A of the plate valve 106A extends from the base plate portion 351 in the axial direction toward the disk 135 and abuts on the outer side of the through holes 141 in the radial direction of the disk 135 over the entire periphery while elastically deforming.

[0136] Within the recessed portion 65 of the piston 15, between the axial orifice disc 102 and the outer seat portion 54, and between the radial outer passage forming portion 44 and the disc 103, the spring disc 104, the valve disc 105, the disc 135, the plate valve 106A, the passage disc 108, the passage disc 109, the orifice disc 110 and the seat disc 111, is an outer volume chamber 171A (volume chamber) similar to the outer volume chamber 171.

[0137] The area surrounded by the valve disc 105, disc 135, plate valve 106A, and spacer 107 forms an inner volume chamber 173A (volume chamber) similar to the inner volume chamber 173, which communicates with the common passage 172 via passages within the through hole 352 of the plate valve 106A, the through hole 145 of the passage disc 108, the through hole 148 of the passage disc 109, the through hole 152 of the orifice disc 110, the through hole 157 of the seat disc 111, and the notch 163 of the valve disc 112.

[0138] When the disc 135 deforms axially toward the passage disc 108 together with the outer periphery of the valve disc 105 so as to shorten the spring plate portion 136A of the plate valve 106A in the axial direction, the volume of the outer volume chamber 171A increases and the volume of the inner volume chamber 173A decreases. The portion of the recessed portion 65 of the piston 15 between the orifice disc 102 and the outer seat portion 54 in the axial direction, the orifice disc 102, the disc 103, the spring disc 104, the valve disc 105, the disc 135, the plate valve 106A, the spacer 107, the passage disc 108, the passage disc 109, the orifice disc 110, and the seat disc 111 constitute a volume variable mechanism 175A similar to the volume variable mechanism 175, which changes the volumes of the outer volume chamber 171A and the inner volume chamber 173A. The volume variable mechanism 175A includes the plate valve 106A.

[0139] 11 and 12, the shock absorber 1A is provided with a disk 235 of the chamber-forming disk 206 and a plate valve 206A, which is a disc spring separate from the disk 235, instead of the chamber-forming disk 206 of the shock absorber 1. The plate valve 206A has the same configuration as the plate valve 106A, and the disk 235 has the same configuration as the disk 135.

[0140] In the shock absorber 1A, a disk 235 is disposed between the axial valve disk 205 and the spacer 207, and a plate valve 206A is disposed between the axial spacer 207 and the passage disk 208, both of which are fitted radially inward below the inner passage forming portion 43 of the boss portion 42 of the piston 15.

[0141] 15 and 16, the plate valve 206A has a base plate portion 361 similar to the base plate portion 351 of the plate valve 106A, and a spring plate portion 236A similar to the spring plate portion 136A of the plate valve 106A. The base plate portion 361 has a plurality of through holes 362 formed therein similar to the plurality of through holes 352 of the base plate portion 351.

[0142] The plate valve 206A is sandwiched between the spacer 207 and the passage disk 208, with the base plate portion 361 fitted radially inwardly at a portion lower than the inner passage forming portion 43 of the boss portion 42 of the piston 15. In this state, the through hole 362 of the base plate portion 361 communicates with the through hole 245 of the passage disk 208. The plate valve 206A has the spring plate portion 236A extending from the base plate portion 361 in the axial direction toward the disk 235 and abutting on the outer side of the through hole 241 in the radial direction of the disk 235 over its entire circumference while elastically deforming.

[0143] Within the recessed portion 66 of the piston 15, between the axial orifice disc 202 and the outer seat portion 55, and between the radial outer passage forming portion 44 and the disc 203, the spring disc 204, the valve disc 205, the disc 235, the plate valve 206A, the passage disc 208, the passage disc 209, the orifice disc 210 and the seat disc 211, forms an outer volume chamber 271A (volume chamber) similar to the outer volume chamber 271.

[0144] The portion surrounded by the valve disc 205, disc 235, plate valve 206A, and spacer 207 forms an inner volume chamber 273A (volume chamber) similar to the inner volume chamber 273, which communicates with the common passage 172 via passages within the through hole 362 of the plate valve 206A, the through hole 245 of the passage disc 208, the through hole 248 of the passage disc 209, the through hole 252 of the orifice disc 210, the through hole 257 of the seat disc 211, and the notch 263 of the valve disc 212.

[0145] When the disc 235 deforms axially toward the passage disc 208 together with the outer periphery of the valve disc 205 so as to shorten the spring plate portion 236A of the plate valve 206A in the axial direction, the volume of the outer volume chamber 271A increases and the volume of the inner volume chamber 273A decreases. The portion of the recessed portion 66 of the piston 15 between the orifice disc 202 and the outer seat portion 55 in the axial direction, the orifice disc 202, the disc 203, the spring disc 204, the valve disc 205, the disc 235, the plate valve 206A, the spacer 207, the passage disc 208, the passage disc 209, the orifice disc 210, and the seat disc 211 constitute a volume variable mechanism 275A similar to the volume variable mechanism 275, which changes the volumes of the outer volume chamber 271A and the inner volume chamber 273A. The volume variable mechanism 275A includes the plate valve 206A.

[0146] 13, the pressure in the first chamber 21 becomes higher than the pressure in the common passage 172, which has substantially the same pressure as the second chamber 22. Then, the oil L in the first chamber 21 flows through the passages in the plurality of passage grooves 71 of the piston 15, through the first orifice 121 of the orifice disc 102, and into the outer volume chamber 171A. Then, the pressure in the outer volume chamber 171A becomes higher than the pressure in the inner volume chamber 173A, so that the outer peripheral side of the disc 135 of the volume variable mechanism 175A bends toward the passage disc 108 together with the outer peripheral side of the valve disc 105 while axially contracting the spring plate portion 136A of the plate valve 106A, thereby expanding the volume of the outer volume chamber 171A and reducing the volume of the inner volume chamber 173A. Then, the oil liquid L that was in the inner volume chamber 173A flows through the passage in the through hole 352 of the plate valve 106A, the passage in the through hole 145 of the passage disk 108, the passage in the through hole 148 of the passage disk 109, the passage in the through hole 152 of the orifice disk 110, the passage in the through hole 157 of the seat disk 111, the passage in the notch 163 of the valve plate portion 161 of the valve disk 112, the common passage 172, the passage in the notch 263 of the valve plate portion 261 of the valve disk 212 shown in FIG. 15, the through hole 152 of the orifice disk 110, the passage in the through hole 157 of the seat disk 111, the common passage 172, the passage in the notch 263 of the valve plate portion 261 of the valve disk 212 shown in FIG. The fluid enters the inner volume chamber 273A through the passage in the hole 257, the passage in the through-hole 252 of the orifice disk 210, the passage in the through-hole 248 of the passage disk 209, the passage in the through-hole 245 of the passage disk 208, and the passage in the through-hole 362 of the plate valve 206A, passes through the passage in the through-hole 241 of the disk 235, opens the check valve 285, and flows into the second chamber 22 through the outer volume chamber 271A, the first orifice 221 of the orifice disk 202, and the passage in the passage groove 72 of the piston 15 shown in FIG. 16.

[0147] Furthermore, during the extension stroke, the first chamber 21 shown in FIG. 13 becomes higher in pressure than the second chamber 22, i.e., the common passage 172, which has approximately the same pressure as the second chamber 22, and the oil L in the first chamber 21 flows through the first orifice 121 of the orifice disc 102 into the outer volume chamber 171A. When the pressure in the outer volume chamber 171A becomes higher than the common passage 172 by a predetermined value or more, the extension side damping force generating mechanism 181 opens and the oil L in the outer volume chamber 171A flows into the common passage 172 via the second orifice 151 of the orifice disc 110, the passage in the through hole 156 of the seat disc 111, and the passage between the valve plate portion 161 of the valve disc 112 of the extension side damping force generating mechanism 181 that has opened and the seat disc 111. The oil liquid L that has flowed into the common passage 172 passes through the passage in the cutout portion 263 of the valve plate portion 261 of the valve disc 212 shown in FIG. 15 , the passage in the through hole 257 of the seat disc 211, the passage in the through hole 252 of the orifice disc 210, the passage in the through hole 248 of the passage disc 209, the passage in the through hole 245 of the passage disc 208, and the passage in the through hole 362 of the plate valve 206A, enters the inner volume chamber 273A, passes through the passage in the through hole 241 of the disc 235, opens the check valve 285, and flows into the second chamber 22 through the outer volume chamber 271A, the first orifice 221 of the orifice disc 202, and the passage in the passage groove 72 of the piston 15 shown in FIG. 16 .

[0148] As described above, the second passage 301A is constituted by a passage including the second passage hole 68, which allows the oil L flowing out from the first chamber 21 of the piston 15 to flow toward the second chamber 22. The second passage 301A includes passages in the plurality of passage grooves 71 of the piston 15 shown in FIG. 13 , the first orifice 121 of the orifice disc 102, and the outer volume chamber 171A. The second passage 301A also includes the second orifice 151 of the orifice disc 110, a passage in the through-hole 156 of the seat disc 111, and a passage between the seat disc 111 and the valve plate portion 161 of the valve disc 112 of the extension-side damping force generating mechanism 181 in the valve-open state. The second passage 301A includes the common passage 172, a passage in the cutout portion 263 of the valve plate portion 261 of the valve disc 212 shown in FIG. 15, a passage in the through hole 257 of the seat disc 211, a passage in the through hole 252 of the orifice disc 210, a passage in the through hole 248 of the passage disc 209, a passage in the through hole 245 of the passage disc 208, a passage in the through hole 362 of the plate valve 206A, the inner volume chamber 273A, a passage in the through hole 241 of the disc 235, a passage between the disc 235 and the valve disc 205 of the check valve 285 that is opened, the outer volume chamber 271A, the first orifice 221 of the orifice disc 202, and passages in the plurality of passage grooves 72 of the piston 15 shown in FIG. 16.

[0149] The extension side damping force generating mechanism 181 shown in Figure 13 opens and closes this second passage 301A. The extension side damping force generating mechanism 181 is provided in the second passage 301A and opens and closes the second passage 301A. When the second passage 301A is open, hydraulic oil L flows from the first chamber 21 (upstream) to the second chamber 22 (downstream), thereby generating a damping force. The second passage 301A is a passage through which hydraulic oil L flows from the first chamber 21 (upstream) to the second chamber 22 (downstream), as the piston 15 moves during the extension stroke. The second passage 301A is provided in parallel with the first passage 86 through which hydraulic oil L flows from the first chamber 21 (upstream) to the second chamber 22 (downstream), as the piston 15 moves during the extension stroke. Therefore, the extension side damping force generating mechanism 181, which operates during the extension stroke, is provided in parallel with the first damping force generating mechanism 87 shown in Figure 15, which also operates during the extension stroke. The extension damping force generating mechanism 181 shown in FIG. 13 is disposed inside the piston 15 and in the second passage hole 68 that constitutes a second passage 301A that is parallel to the first passage 86 .

[0150] The main valve 82 of the first damping force generating mechanism 87 (shown in FIG. 15 ) provided in the first extension passage 86 has a higher valve opening pressure than the valve disc 112 of the extension damping force generating mechanism 181 (shown in FIG. 13 ) provided in the second extension passage 301A. This allows the extension damping force generating mechanism 181 to operate and generate damping force before the first damping force generating mechanism 87 operates. The extension damping force generating mechanism 181 is provided in the second passage 301A. It opens when the piston speed is low, while the first damping force generating mechanism 87 is closed. When the piston speed is higher than low, it opens together with the first damping force generating mechanism 87. The volume variable mechanism 175A provided in the second passage 301A operates before the extension damping force generating mechanism 181 and the first damping force generating mechanism 87 operate, changing the volumes of the outer volume chamber 171A and the inner volume chamber 173A. At this time, the check valve 285 (shown in FIG. 16 ) opens.

[0151] 16 , the second chamber 22 becomes higher in pressure than the first chamber 21, i.e., the common passage 172, which has substantially the same pressure as the first chamber 21. Then, the oil L in the second chamber 22 flows through the passages in the plurality of passage grooves 72 of the piston 15 and the first orifice 221 of the orifice disc 202 into the outer volume chamber 271A. Then, the pressure in the outer volume chamber 271A becomes higher than the pressure in the inner volume chamber 273A, so that the volume variable mechanism 275A bends toward the passage disc 208 together with the outer circumference of the valve disc 205 while axially contracting the spring plate portion 236A of the plate valve 206A, thereby expanding the volume of the outer volume chamber 271A and reducing the volume of the inner volume chamber 273A. Then, the oil L in the inner volume chamber 273A flows through the passage in the through hole 362 of the plate valve 206A, the passage in the through hole 245 of the passage disk 208, the passage in the through hole 248 of the passage disk 209, the passage in the through hole 252 of the orifice disk 210, the passage in the through hole 257 of the seat disk 211, the passage in the notch 263 of the valve plate portion 261 of the valve disk 212, the common passage 172, the passage in the notch 163 of the valve plate portion 161 of the valve disk 112 shown in FIG. 14, the through hole 252 of the orifice disk 210, the common passage 172, the passage in the notch 163 of the valve plate portion 161 of the valve disk 112 shown in FIG. The fluid enters the inner volume chamber 173A through the passage in the hole 157, the passage in the through-hole 152 of the orifice disk 110, the passage in the through-hole 148 of the passage disk 109, the passage in the through-hole 145 of the passage disk 108, and the passage in the through-hole 352 of the plate valve 106A, passes through the passage in the through-hole 141 of the disk 135, opens the check valve 185, and flows into the first chamber 21 through the outer volume chamber 171A, the first orifice 121 of the orifice disk 102, and the passage in the passage groove 71 of the piston 15 shown in FIG. 13.

[0152] Furthermore, the second chamber 22 shown in FIG. 16 becomes higher in pressure than the first chamber 21, i.e., the common passage 172, which has approximately the same pressure as the first chamber 21, and the oil L in the second chamber 22 flows through the first orifice 221 of the orifice disc 202 into the outer volume chamber 271A. When the pressure in the outer volume chamber 271A becomes higher than the common passage 172 by a predetermined value or more, the compression side damping force generating mechanism 281 opens and the oil L in the outer volume chamber 271A flows into the common passage 172 via the second orifice 251 of the orifice disc 210, the passage in the through hole 256 of the seat disc 211, and the passage between the valve plate portion 261 of the valve disc 212 of the compression side damping force generating mechanism 281 that has opened and the seat disc 211. The oil liquid L that has flowed into the common passage 172 passes through the passage in the cutout portion 163 of the valve plate portion 161 of the valve disc 112 shown in FIG. 14 , the passage in the through hole 157 of the seat disc 111, the passage in the through hole 152 of the orifice disc 110, the passage in the through hole 148 of the passage disc 109, the passage in the through hole 145 of the passage disc 108, and the passage in the through hole 352 of the plate valve 106A, enters the inner volume chamber 173A, passes through the passage in the through hole 141 of the disc 135, opens the check valve 185, and flows into the first chamber 21 through the outer volume chamber 171A, the first orifice 121 of the orifice disc 102, and the passage in the passage groove 71 of the piston 15 shown in FIG. 13.

[0153] As described above, the second passage 302A is constituted by a passage including the second passage hole 68, which allows the oil L flowing out of the second chamber 22 shown in Fig. 16 in the piston 15 to flow toward the first chamber 21. The second passage 302A includes passages in the plurality of passage grooves 72 of the piston 15, the first orifice 221 of the orifice disc 202, and the outer volume chamber 271A. The second passage 302A also includes the second orifice 251 of the orifice disc 210, a passage in the through-hole 256 of the seat disc 211, and a passage between the seat disc 211 and the valve plate portion 261 of the valve disc 212 of the compression-side damping force generating mechanism 281 in the valve-open state. The second passage 302A includes the common passage 172, a passage within the notch 163 of the valve plate portion 161 of the valve disc 112 shown in FIG. 14, a passage within the through hole 157 of the seat disc 111, a passage within the through hole 152 of the orifice disc 110, a passage within the through hole 148 of the passage disc 109, a passage within the through hole 145 of the passage disc 108, a passage within the through hole 352 of the plate valve 106A, the inner volume chamber 173A, a passage within the through hole 141 of the disc 135, a passage between the disc 135 and the valve disc 105 of the check valve 185 that is opened, the outer volume chamber 171A, the first orifice 121 of the orifice disc 102, and passages within the plurality of passage grooves 71 of the piston 15 shown in FIG. 13.

[0154] The compression side damping force generating mechanism 281 shown in FIG. 16 opens and closes this second passage 302A. The compression side damping force generating mechanism 281 is provided in the second passage 302A and opens and closes the second passage 302A. When the second passage 302A is open, hydraulic oil L flows from the second chamber 22, which is located upstream, to the first chamber 21, which is located downstream. The second passage 302A is a passage through which hydraulic oil L flows from the second chamber 22, which is located upstream, to the first chamber 21, which is located downstream, as the piston 15 moves during the compression stroke. The second passage 302A is provided in parallel with the first passage 96, through which hydraulic oil L flows from the second chamber 22, which is located upstream, to the first chamber 21, which is located downstream, as the piston 15 moves during the compression stroke. Therefore, the compression side damping force generating mechanism 281, which operates during the compression stroke, is provided in parallel with the first damping force generating mechanism 97, shown in FIG. 14, which also operates during the compression stroke. The compression-side damping force generating mechanism 281 shown in FIG. 16 is disposed inside the piston 15 and in the second passage hole 68 that constitutes a second passage 302A that is parallel to the first passage 96 .

[0155] The main valve 92 of the first damping force generating mechanism 97 (shown in FIG. 14 ) provided in the first compression passage 96 has a higher valve opening pressure than the valve disc 212 of the compression damping force generating mechanism 281 (shown in FIG. 16 ) provided in the second compression passage 302A. As a result, the compression damping force generating mechanism 281 operates to generate damping force before the first damping force generating mechanism 97 operates. The compression damping force generating mechanism 281 is provided in the second passage 302A and opens while the first damping force generating mechanism 97 is closed in the low piston speed range, and opens together with the first damping force generating mechanism 97 in the speed range above low piston speed. The volume variable mechanism 275A provided in the second passage 302A operates before the compression damping force generating mechanism 281 and the first damping force generating mechanism 97 operate to change the volumes of the outer volume chamber 271A and the inner volume chamber 273A. At this time, the check valve 185 shown in FIG. 14 opens.

[0156] A second damping force generating mechanism 311 having an extension side damping force generating mechanism 181 and a compression side damping force generating mechanism 281 is disposed inside the piston 15 and is disposed within the second passage hole 68 which constitutes second passages 301A, 302A parallel to the first passages 86, 96.

[0157] An orifice disk 102 having a first orifice 121 formed therein is provided in a position facing the first chamber 21 on the side of the second damping force generating mechanism 311 in the second passage 301A of the piston 15 that is closer to the first chamber 21 shown in Fig. 13 than the second damping force generating mechanism 311. Furthermore, an orifice disk 202 having a first orifice 221 formed therein is provided in a position facing the second chamber 22 on the side of the second passage 302A of the piston 15 that is closer to the second chamber 22 shown in Fig. 16 than the second damping force generating mechanism 311. The second damping force generating mechanism 311, the volume variable mechanism 175A that changes the volumes of the outer volume chamber 171A and the inner volume chamber 173A, and the volume variable mechanism 275A that changes the volumes of the outer volume chamber 271A and the inner volume chamber 273A are all disposed radially away from the piston rod 31 of the piston 15.

[0158] <Operation> The operation of the shock absorber 1A differs from the operation of the shock absorber 1 in the following respects: The volume variable mechanism 175A bends the outer circumferential side of the disk 135 toward the passage disk 108 while causing the spring plate portion 136A of the plate valve 106A to contract in the axial direction, thereby expanding the volume of the outer volume chamber 171A and reducing the volume of the inner volume chamber 173A.

[0159] The volume variable mechanism 275A causes the outer circumferential side of the disk 235 to contract and elongate the spring plate portion 236A of the plate valve 206A in the axial direction, and bends together with the outer circumferential side of the valve disk 205 toward the passage disk 208, thereby expanding the volume of the outer volume chamber 271A and reducing the volume of the inner volume chamber 273A.

[0160] Instead of the flow of oil liquid L in the second passage 301, oil liquid L is made to flow in the second passage 301A, and instead of the flow of oil liquid L in the second passage 302, oil liquid L is made to flow in the second passage 302A.

[0161] The shock absorber 1A of the second embodiment can achieve substantially the same effects as the shock absorber 1 of the first embodiment.

[0162] Furthermore, in the shock absorber 1A of the second embodiment, the volume variable mechanism 175A uses a metal disk 135 and a metal plate valve 106A instead of the chamber forming disk 106 having the metal disk 135 and the rubber seal portion 136, and the volume variable mechanism 275A uses a metal disk 235 and a metal plate valve 206A instead of the chamber forming disk 206 having the metal disk 235 and the rubber seal portion 236. Therefore, the shock absorber 1A can improve the durability of the volume variable mechanisms 175A and 275A.

[0163] According to the shock absorber according to the above aspect of the present disclosure, the configuration around the piston can be made compact.

[0164] REFERENCE SIGNS LIST 1, 1A... shock absorber, 11... cylinder, 15... piston, 21... first chamber, 22... second chamber, 68... second passage hole (passage hole), 86, 96... first passage, 87, 97... first damping force generating mechanism, 102, 202... orifice disc (first orifice member), 106A, 206A... plate valve, 135, 235... disc, 171, 171A, 271, 271A... outer Side volume chamber (volume chamber), 172...common passage, 173, 173A, 273, 273A...inner volume chamber (volume chamber), 175, 175A...volume variable mechanism, 181...extension side damping force generating mechanism, 185, 285...check valve, 281...compression side damping force generating mechanism, 301, 301A, 302, 302A...second passage, 311...second damping force generating mechanism, L...oil (working fluid).

Claims

1. A shock absorber comprising: a cylinder filled with working fluid; a piston slidably fitted within said cylinder and dividing the interior of said cylinder into one side chamber and the other side chamber; a first passage and a second passage through which working fluid flows from an upstream chamber to a downstream chamber within said cylinder as said piston moves; a first damping force generating mechanism provided in said first passage and generating a damping force; and a second damping force generating mechanism disposed inside said piston and disposed within a passage hole that constitutes said second passage which is parallel to said first passage.

2. A shock absorber as set forth in claim 1, wherein the second damping force generating mechanism has an extension damping force generating mechanism disposed on one side of the passage hole and a compression damping force generating mechanism disposed on the other side.

3. A shock absorber as set forth in claim 2, wherein a common passage through which working fluid flows during both the extension stroke and the compression stroke is disposed between the extension-side damping force generating mechanism and the compression-side damping force generating mechanism.

4. A shock absorber as claimed in any one of claims 1 to 3, wherein a volume chamber and a volume variable mechanism for changing the volume of the volume chamber are provided in parallel with the second damping force generating mechanism.

5. The shock absorber according to claim 4, wherein said volume variable mechanism has a disk with rubber baked on it.

6. The shock absorber according to claim 4, wherein the volume variable mechanism has a plate valve.

7. A shock absorber as described in claim 4, wherein the volume variable mechanism is provided with a check valve that allows the flow of oil liquid L from one side chamber to the other side chamber, while restricting the flow of oil liquid L from the other side chamber to the one side chamber.

8. A shock absorber according to claim 1, wherein a first orifice member is provided in the second passage at a position facing the chamber on the chamber side of the second damping force generating mechanism.

9. The shock absorber according to claim 1, wherein the piston is provided with the first passage and the first damping force generating mechanism.

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