Buffer

Abstract

To provide a buffer capable of realizing space saving and cost reduction.SOLUTION: A buffer comprises: a first attenuation force generation mechanism 41 that is provided in a first passage 92, and operates when a piston 21 moves to cause working fluid L to flow into the first passage 92, thereby generating an attenuation force; variable volume mechanisms 185, 186 that are provided in a second passage 172, and operate when the piston 21 moves to cause the working fluid to flow into the second passage 172 from an upstream chamber in a cylinder 4, comprise storage chambers 147, 149 that store the working fluid from the upstream chamber; and communication mechanisms 174, 184 that are provided in the variable volume mechanisms 185, 186, and communicate the storage chambers 147, 149 with a downstream chamber of the cylinder 4 when the variable volume mechanisms 185, 186 are displaced by a predetermined amount or more.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Some shock absorbers have two damping force generating mechanisms that open in the same stroke (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 024766 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, there is a demand for space saving and cost reduction in shock absorbers.

[0005] An object of the present invention is to provide a shock absorber that can save space and reduce costs. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention is configured to include a cylinder containing a working fluid, a piston slidably mounted in the cylinder and dividing the interior of the cylinder into two chambers, a piston rod connected to the piston at one end and extending outside the cylinder at the other end, a first passage through which the working fluid flows from an upstream chamber of the cylinder to a downstream chamber as the piston moves, a second passage arranged in parallel to the first passage, a first damping force generating mechanism arranged in the first passage and operating when the piston moves to cause the working fluid to flow into the first passage, thereby generating a damping force, a volume variable mechanism arranged in the second passage and operating when the piston moves to cause the working fluid to flow from the upstream chamber in the cylinder into the second passage, the volume variable mechanism having a storage chamber for storing the working fluid in the upstream chamber, and a communication mechanism arranged in the volume variable mechanism for communicating the storage chamber with a downstream chamber of the cylinder when the volume variable mechanism is displaced by a predetermined amount or more. [Effects of the Invention]

[0007] According to the present invention, it is possible to achieve space saving and cost reduction. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a shock absorber according to an embodiment of the present invention. [Figure 2] 1 is a partial cross-sectional view showing a main part of a shock absorber according to an embodiment of the present invention. [Figure 3] FIG. 2 is a partial cross-sectional view showing details of a main part of a shock absorber according to an embodiment of the present invention. [Figure 4] 1 is a hydraulic circuit diagram showing a main part of a shock absorber according to an embodiment of the present invention. [Figure 5] 1A and 1B are partial cross-sectional views showing the main parts of a shock absorber according to an embodiment of the present invention, in which arrows indicate the flow of oil during the extension stroke in FIG. 1A and the flow of oil during the compression stroke in FIG. [Figure 6]1 is a partial cross-sectional view showing details of a main part of a shock absorber according to an embodiment of the present invention, in which arrows indicate the flow of oil. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments will be described with reference to the drawings. For the sake of convenience, the upper side of the drawings will be referred to as "top" and the lower side of the drawings will be referred to as "bottom."

[0010] <Configuration> The shock absorber 1 of the embodiment is a shock absorber used in the suspension system of railway vehicles and automobiles such as two-wheeled and four-wheeled vehicles, and specifically, a shock absorber used in the suspension system of four-wheeled automobiles. As shown in Fig. 1, the shock absorber 1 is a double-tube shock absorber equipped with a cylinder 4 having a cylindrical inner tube 2 and a cylindrical outer tube 3 with a bottom that is larger in diameter than the inner tube 2 and is provided radially outward of the inner tube 2. A reservoir chamber 5 is formed between the outer tube 3 and the inner tube 2.

[0011] The outer tube 3 has a stepped cylindrical body member 8 whose axial ends have a smaller diameter than the axial middle portion, and a bottom member 9 that closes the lower end, which is one axial end of the body member 8, and the upper end of the body member 8 opposite the bottom member 9 is an opening.

[0012] The shock absorber 1 has an annular valve body 10 provided at the lower end, which is one axial end of the inner cylinder 2, and an annular rod guide 11 provided at the upper ends, which are the other axial ends of the inner cylinder 2 and the outer cylinder 3. The valve body 10 constitutes a base valve 12, and has a stepped outer periphery. The rod guide 11 also has a stepped outer periphery, and its large diameter part is fitted into the body member 8.

[0013] The inner cylinder 2 has an upper end, which is one axial end, fitted into a small-diameter portion on the outer periphery of a valve body 10, and engages with the bottom member 9 of the outer cylinder 3 via this valve body 10. The inner cylinder 2 has a lower end, which is the other axial end, fitted into a small-diameter portion on the outer periphery of a rod guide 11, and engages with the body member 8 of the outer cylinder 3 via this rod guide 11. In this state, the inner cylinder 2 is positioned radially relative to the outer cylinder 3. The space between the valve body 10 and the bottom member 9 is in communication with the inner cylinder 2 and the outer cylinder 3, and constitutes a reservoir chamber 5, just like the space between the inner cylinder 2 and the outer cylinder 3.

[0014] The shock absorber 1 has an annular seal member 13 on the side of the rod guide 11 opposite the bottom member 9. This seal member 13 is also fitted into the inner peripheral portion of the body member 8, similar to the rod guide 11. An engaging portion (not shown) is formed at the end of the body member 8 opposite the bottom member 9 by plastically deforming the body member 8 radially inward by crimping, such as curling. The radially outer portion of the seal member 13 is sandwiched between this engaging portion (not shown) and the rod guide 11. The seal member 13 closes the opening of the outer cylinder 3, and is specifically an oil seal.

[0015] The shock absorber 1 has a resistance force generating mechanism 20 between the rod guide 11 and the seal member 13. The resistance force generating mechanism 20 is annular.

[0016] The shock absorber 1 has a piston 21 provided in a cylinder 4. The piston 21 is slidably provided in an inner tube 2 of the cylinder 4. The piston 21 divides the inner tube 2 into two chambers: an upper chamber 22 and a lower chamber 23. The upper chamber 22 is provided between the piston 21 and a rod guide 11 in the inner tube 2, and the lower chamber 23 is provided between the piston 21 and a valve body 10 in the inner tube 2. The lower chamber 23 is defined as a reservoir chamber 5 by the valve body 10. Within the cylinder 4, the upper chamber 22 and the lower chamber 23 contain oil liquid L as a working fluid, and the reservoir chamber 5 contains gas G and oil liquid L as working fluids.

[0017] The shock absorber 1 is provided with a piston rod 25, one axial end of which is disposed inside the cylinder 4 and connected and fixed to the piston 21, and the other axial end of which extends to the outside of the cylinder 4. The piston rod 25 is made of metal, and passes through the upper chamber 22 but does not pass through the lower chamber 23. Therefore, the upper chamber 22 is a rod-side chamber through which the piston rod 25 passes, and the lower chamber 23 is a bottom-side chamber on the bottom member 9 side of the cylinder 4.

[0018] The piston 21 and the piston rod 25 move together. During the extension stroke of the shock absorber 1, in which the piston rod 25 increases the amount of protrusion from the cylinder 4, the piston 21 moves toward the upper chamber 22, and during the compression stroke of the shock absorber 1, in which the piston rod 25 decreases the amount of protrusion from the cylinder 4, the piston 21 moves toward the lower chamber 23.

[0019] The rod guide 11, resistance force generating mechanism 20, and seal member 13 are all annular, and the piston rod 25 is slidably inserted through the rod guide 11, resistance force generating mechanism 20, and seal member 13, respectively, and extends from the inside to the outside of the cylinder 4. One axial end of the piston rod 25 is fixed to the piston 21 inside the cylinder 4, and the other axial end protrudes to the outside of the cylinder 4 via the rod guide 11, resistance force generating mechanism 20, and seal member 13.

[0020] The rod guide 11 supports the piston rod 25 relative to the cylinder 4 so as to be movable in the axial direction while restricting the movement of the piston rod 25 in the radial direction, thereby guiding the movement of the piston rod 25.

[0021] The outer periphery of the seal member 13 is in close contact with the outer tube 3 of the cylinder 4, and the inner periphery is in sliding contact with the outer periphery of the piston rod 25 that moves in the axial direction. In this way, the seal member 13 prevents the oil L and gas G in the cylinder 4 from leaking to the outside.

[0022] The resistance force generating mechanism 20 is not intended to provide a seal between the piston rod 25 and the rod guide 11, but rather to apply a frictional resistance force to the piston rod 25.

[0023] Piston rod 25 has a cylindrical main shaft portion 30 and a cylindrical mounting shaft portion 31 whose outer diameter is smaller than that of main shaft portion 30. In piston rod 25, main shaft portion 30 is slidably fitted into rod guide 11, resistance force generating mechanism 20, and seal member 13, and mounting shaft portion 31 is disposed in cylinder 4 and connected to piston 21, etc. The end of main shaft portion 30 on the mounting shaft portion 31 side forms a shaft step portion 32 that widens in the direction perpendicular to the axis.

[0024] An axially extending passage cutout 33 is formed in the outer periphery of the mounting shaft portion 31 at an axially intermediate position, and a male thread 34 is formed at a tip position on the opposite side of the axial passage cutout 33 from the main shaft portion 30. As shown in Fig. 2, the passage cutout 33 is formed by cutting out a flat portion of the outer periphery of the mounting shaft portion 31 in a plane parallel to the central axis of the mounting shaft portion 31, and has an axial groove 33a extending in the axial direction of the mounting shaft portion 31, an annular groove 33b provided at the end of the axial groove 33a on the main shaft portion 30 side of the mounting shaft portion 31 in the axial direction, and an annular groove 33c provided at the end of the axial groove 33a on the opposite side of the main shaft portion 30 in the axial direction of the mounting shaft portion 31.

[0025] In shock absorber 1, for example, the portion of piston rod 25 protruding from cylinder 4 is positioned at the top and supported by the vehicle body, and the bottom member 9 of cylinder 4 is positioned at the bottom and connected to the wheel side. In the case of a mono-tube type, it is possible to reverse this and have cylinder 4 supported by the vehicle body and piston rod 25 connected to the wheel side.

[0026] The piston 21 is composed of a metal piston body 36 that is connected to the piston rod 25 and a ring-shaped sliding member 37 made of synthetic resin that is attached integrally to the outer surface of the piston body 36 and slides inside the inner tube 2 of the cylinder 4.

[0027] The piston body 36 is provided with a plurality of passage holes 38 (only one of which is shown in Figure 2 because it is a cross-section) that can connect the upper chamber 22 and the lower chamber 23, and a plurality of passage holes 39 (only one of which is shown in Figure 2 because it is a cross-section) that can connect the upper chamber 22 and the lower chamber 23.

[0028] The multiple passage holes 38 are formed at equal intervals in the circumferential direction of the piston body 36, with one passage hole 39 sandwiched between each adjacent hole, and constitute half of the total number of passage holes 38, 39. The multiple passage holes 38 are crank-shaped with two bending points, and the side facing the lower chamber 23 in the axial direction of the piston 21 opens more inward in the radial direction of the piston 21 than the side facing the upper chamber 22. An annular groove 55 that connects the multiple passage holes 38 is formed in the piston body 36 on the side facing the lower chamber 23 in the axial direction.

[0029] A first damping force generating mechanism 41 is provided on the lower chamber 23 side of the annular groove 55, and generates a damping force by opening and closing the passages in the annular groove 55 and the plurality of passage holes 38. By disposing the first damping force generating mechanism 41 on the lower chamber 23 side, the passages in the plurality of passage holes 38 and the annular groove 55 serve as extension-side passages through which oil L flows from the upper chamber 22, which is on the upstream side, to the lower chamber 23, which is on the downstream side, when the piston 21 moves toward the upper chamber 22, i.e., during the extension stroke. The first damping force generating mechanism 41 provided for the passages in the plurality of passage holes 38 and the annular groove 55 serves as an extension-side damping force generating mechanism that generates a damping force by suppressing the flow of oil L from the passages in the plurality of extension-side passage holes 38 and the annular groove 55 to the lower chamber 23.

[0030] The passage holes 39, which make up the remaining half of the total number of passage holes 38, 39, are formed at equal intervals in the circumferential direction of the piston body 36, with one passage hole 38 sandwiched between each other. The multiple passage holes 39 are crank-shaped with two bending points, and the upper chamber 22 side in the axial direction of the piston 21 opens more inward in the radial direction of the piston 21 than the lower chamber 23 side. An annular groove 56 is formed in the piston body 36 on the upper chamber 22 side in the axial direction, connecting the multiple passage holes 39.

[0031] A first damping force generating mechanism 42 is provided on the upper chamber 22 side of the annular groove 56, and generates a damping force by opening and closing the passages in the plurality of passage holes 39 and the annular groove 56. By disposing the first damping force generating mechanism 42 on the upper chamber 22 side, the passages in the plurality of passage holes 39 and the annular groove 56 become compression-side passages through which oil L flows from the lower chamber 23, which is on the upstream side, to the upper chamber 22, which is on the downstream side, when the piston 21 moves toward the lower chamber 23, that is, during the compression stroke. The first damping force generating mechanism 42 provided for the passages in the plurality of passage holes 39 and the annular groove 56 serves as a compression-side damping force generating mechanism that generates a damping force by suppressing the flow of oil L from the passages in the plurality of compression-side passage holes 39 and the annular groove 56 to the upper chamber 22.

[0032] The piston body 36 is made up of two members: a first constituent body 57 and a second constituent body 58. The first constituent body 57 constitutes the portion of the piston body 36 on the lower chamber 23 side in the axial direction, and the second constituent body 58 constitutes the portion of the piston body 36 on the upper chamber 22 side in the axial direction.

[0033] The first component 57 has a substantially circular plate shape. A through hole 59 that constitutes a part of the insertion hole 44 is formed in the center of the first component 57 in the radial direction, penetrating the first component 57 in the axial direction of the first component 57. The through hole 59 has a large diameter hole portion 59a on the second component 58 side in the axial direction of the first component 57, and a small diameter hole portion 59b that is smaller in diameter than the large diameter hole portion 59a on the opposite side to the second component 58. The small diameter hole portion 59b is a portion of the first component 57 into which the mounting shaft portion 31 of the piston rod 25 is fitted.

[0034] A passage groove 60 extending in the radial direction of the first component 57 is formed on the end face of the first component 57 on the second component 58 side in the axial direction. The passage groove 60 communicates with the passage in the large diameter hole portion 59a. The passage in the passage groove 60 constitutes an orifice 62. The orifice 62 communicates with the passage in the large diameter hole portion 59a and the passage in the passage hole 38.

[0035] The above-mentioned annular groove 55 is formed at the end of the first component 57 on the lower chamber 23 side in the axial direction. An annular valve seat portion 48 that constitutes part of the first damping force generating mechanism 41 is formed at the end of the first component 57 on the lower chamber 23 side in the axial direction, radially outward from the opening of the annular groove 55 on the lower chamber 23 side. Furthermore, an inner seat portion 47 is formed at the end of the piston body 36 on the lower chamber 23 side in the axial direction, radially inward from the opening of the annular groove 55 on the lower chamber 23 side.

[0036] The first component 57 has an engaging protrusion (not shown) formed on the end face of the first component 57 on the second component 58 side in the axial direction of the first component 57. The engaging protrusion is provided partially in the circumferential direction of the first component 57.

[0037] The second component 58 has a substantially circular plate shape. A circular through-hole 61 is formed in the radial center of the second component 58, penetrating the second component 58 in the axial direction of the second component 58. The through-hole 61 is a portion of the second component 58 into which the mounting shaft portion 31 of the piston rod 25 is fitted.

[0038] The above-mentioned annular groove 56 is formed at the end of the second component 58 on the upper chamber 22 side in the axial direction. An annular valve seat portion 50 that constitutes a part of the first damping force generating mechanism 42 is formed at the end of the second component 58 on the upper chamber 22 side in the axial direction, radially outward from the opening of the annular groove 56 on the upper chamber 22 side. Furthermore, an inner seat portion 49 is formed at the end of the piston body 36 on the upper chamber 22 side in the axial direction, radially inward from the opening of the annular groove 56 on the upper chamber 22 side.

[0039] In the second component 58, an engagement recess (not shown) is formed that is recessed inward along the axial direction of the second component 58 from the end face of the second component 58 on the first component 57 side in the axial direction of the second component 58. The engagement recess is provided partially in the circumferential direction of the second component 58.

[0040] The first component 57 and the second component 58 are connected by engaging an engaging protrusion (not shown) of the first component 57 with an engaging recess (not shown) of the second component 58. As a result, the first component 57 and the second component 58 are connected in a state where they are positioned in the circumferential direction so as to form the passage holes 38 and 39. In this state, the sliding member 37 is placed over the radially outside of the first component 57 and the second component 58. As a result, the first component 57 and the second component 58 are integrated to form the piston main body 36, and the first component 57, the second component 58, and the sliding member 37 are integrated to form the piston 21.

[0041] In the first component 57, the opening of the compression-side passage hole 39 on the lower chamber 23 side is disposed radially outward of the valve seat portion 48. In the second component 58, the opening of the extension-side passage hole 38 on the upper chamber 22 side is disposed radially outward of the valve seat portion 50.

[0042] In the piston 21, the orifice 62 in the passage groove 60 of the first component 57 and the passage in the large diameter hole portion 59a are positioned to overlap with the annular groove 33b of the piston rod 25 in the axial direction of the piston rod 25. This allows the orifice 62 to communicate with the passages in the annular groove 33b, axial groove 33a, and annular groove 33c of the piston rod 25 via the passage in the large diameter hole portion 59a of the piston 21, even without circumferentially aligning the phase of the piston 21 with the piston rod 25.

[0043] The compression-side first damping force generating mechanism 42 includes the valve seat portion 50 of the piston 21 and has, in axial order from the piston 21 side, one disc 63, one disc 64, multiple discs 65, one disc 66, one disc 67, and one washer 69. The discs 63 to 67 and the washer 69 are made of metal and are each in the form of a perforated circular flat plate of a uniform thickness. The discs 63 to 67 and the washer 69 are all positioned radially relative to the piston rod 25 by fitting the mounting shaft portion 31 inside them.

[0044] The disk 63 has an outer diameter larger than the outer diameter of the inner seat portion 49 of the piston 21 and smaller than the inner diameter of the valve seat portion 50, and is in constant contact with the inner seat portion 49.

[0045] The disc 64 has an outer diameter equal to the outer diameter of the valve seat portion 50 of the piston 21, and is able to seat on the valve seat portion 50. The disc 64 has a notch 64a on its outer periphery. The passage within the notch 64a forms a fixed orifice 64b that connects the passage within the annular groove 56 of the piston 21 to the upper chamber 22, even when the disc 64 is in contact with the valve seat portion 50.

[0046] The outer diameters of the plurality of discs 65 on the disc 64 side are the same as the outer diameter of the disc 64, and the outer diameters of the plurality of discs 65 on the opposite side to the disc 64 are smaller than the outer diameter of the disc 64.

[0047] The disc 66 has an outer diameter smaller than the outer diameter of the smallest disc 65 among the plurality of discs 65 and smaller than the outer diameter of the inner seat portion 49 of the piston 21 .

[0048] The disk 67 has an outer diameter larger than the outer diameter of the disk 66 and smaller than the outer diameter of the largest of the plurality of disks 65 .

[0049] The washer 69 has an outer diameter smaller than that of the disc 67 and larger than that of the shaft step 32 of the piston rod 25. The washer 69 is thicker and more rigid than the discs 63 to 67, and is in contact with the shaft step 32.

[0050] The disc 64 and the multiple discs 65 constitute a compression-side main valve 71 that is releasable from the valve seat portion 50. When the main valve 71 is releasable from the valve seat portion 50, it connects the passages in the multiple passage holes 39 and the annular groove 56 with the upper chamber 22, and generates a damping force by suppressing the flow of oil L between the valve seat portion 50. The washer 69, together with the disc 67, abuts against the main valve 71 to restrict deformation of the main valve 71 in the opening direction beyond a specified limit.

[0051] The passages within the multiple passage holes 39 and the annular groove 56, and the passage between the main valve 71 and the valve seat 50 that appears when the valve is open, are formed in the piston 21, and constitute a first compression passage 72 that distributes oil L from the lower chamber 23, which is on the upstream side within the cylinder 4, to the upper chamber 22, which is on the downstream side, as the piston 21 moves toward the lower chamber 23. The first compression damping force generating mechanism 42 that generates a damping force includes the main valve 71 and the valve seat 50, and is therefore provided in this first passage 72. The first passage 72 is formed in the piston 21 including the valve seat 50, and oil L passes through the first passage 72 when the piston rod 25 and piston 21 move toward the compression side.

[0052] The first extension-side damping force generating mechanism 41 includes the valve seat portion 48 of the piston 21 and has, in axial order from the piston 21 side, one disc 83, one disc 84, multiple discs 85, and multiple discs 86. The discs 83 to 86 are made of metal and are each in the form of a perforated circular flat plate of a uniform thickness. The discs 83 to 86 are each positioned radially relative to the piston rod 25 by fitting the mounting shaft portion 31 inside thereof.

[0053] The disk 83 has an outer diameter larger than the outer diameter of the inner seat portion 47 of the piston 21 and smaller than the inner diameter of the valve seat portion 48, and is in constant contact with the inner seat portion 47.

[0054] The disc 84 has an outer diameter equal to the outer diameter of the valve seat portion 48 of the piston 21, and is able to seat on the valve seat portion 48. The disc 84 has a notch 84a on its outer periphery. The passage within the notch 84a forms a fixed orifice 84b that connects the passage within the annular groove 55 of the piston 21 to the lower chamber 23, even when the disc 84 is in contact with the valve seat portion 48.

[0055] The outer diameters of the plurality of disks 85 on the disk 84 side are the same as the outer diameter of the disk 84, and the outer diameters of the plurality of disks 85 on the opposite side to the disk 84 are smaller than the outer diameter of the disk 84.

[0056] The plurality of discs 86 have the same outer diameter, which is smaller than the outer diameter of the smallest disc 85 among the plurality of discs 85 and smaller than the outer diameter of the inner seat portion 47 of the piston 21.

[0057] The disc 84 and the plurality of discs 85 constitute an extension-side main valve 91 that can be seated on and removed from the valve seat portion 48. When the main valve 91 is lifted from the valve seat portion 48, the main valve 91 connects the passages in the annular groove 55 and the plurality of passage holes 38 to the lower chamber 23, and suppresses the flow of oil L between the main valve 91 and the valve seat portion 48, thereby generating a damping force.

[0058] The passages within the multiple passage holes 38 and the annular groove 55, and the passage between the main valve 91 and the valve seat 48 that appears when the valve is open, are formed in the piston 21, and constitute a first extension-side passage 92 through which oil L flows from the upper chamber 22, which is the upstream side within the cylinder 4, to the lower chamber 23, which is the downstream side, as the piston 21 moves toward the upper chamber 22. The first extension-side damping force generating mechanism 41 that generates a damping force includes the main valve 91 and the valve seat 48, and is therefore provided in this first passage 92. The first passage 92 is formed in the piston 21 including the valve seat 48, and oil L passes through the first passage 92 when the piston rod 25 and piston 21 move toward the extension side.

[0059] On the opposite side of the disk 86 of the first damping force generating mechanism 41 on the extension side from the piston 21, there are provided, in order from the disk 86 side, one case member 95, one valve member 96, one disk 97, one flexible disk 100 (plate member), one disk 101, one disk 102, one disk 103, and one blocking member 109 with one O-ring 108 on the outer periphery, with the mounting shaft portion 31 of the piston rod 25 fitted inside each of them.

[0060] A male thread 34 is formed on the mounting shaft portion 31 of the piston rod 25 in a portion that protrudes beyond the closing member 109, and a nut 119 is screwed onto this male thread 34. The nut 119 abuts against the closing member 109.

[0061] At least the radially inner circumferential sides of the washer 69, discs 63 to 67, piston 21, discs 83 to 86, case member 95, valve member 96, disc 97, flexible disc 100, discs 101 to 103, and closing member 109 are clamped in the axial direction by the shaft step portion 32 of piston rod 25 and a nut 119, and are fixed to piston rod 25. In this state, the valve member 96, disc 97, flexible disc 100, discs 101 to 103, and closing member 109 are disposed inside the case member 95. The valve member 96 and flexible disc 100 are fixed to the piston rod 25 on the inner circumferential side, which is one radial end, and on the outer circumferential side, which is the other radial end, which is formed as a free end.

[0062] The case member 95, valve member 96, discs 97, 101 to 103, flexible disc 100, and closing member 109 are all made of metal. The discs 97, 101 to 103, and flexible disc 100 are all perforated circular flat plates of a uniform thickness. The valve member 96, case member 95, and closing member 109 are all annular.

[0063] The case member 95 is a cylindrical, one-piece molded product with a bottom, and is formed, for example, by plastic processing or cutting a metal plate. As shown in Fig. 3, the case member 95 has a perforated, disc-shaped bottom portion 122 of a constant thickness, a middle curved portion 123 that extends from the outer peripheral edge of the bottom portion 122 toward one axial direction of the bottom portion 122 while expanding in diameter, and a cylindrical portion 124 that extends in the opposite direction from the edge of the middle curved portion 123 opposite the bottom portion 122.

[0064] The bottom portion 122 has a constant radial width around its entire circumference and is a circular, flat plate with holes. The mounting shaft portion 31 of the piston rod 25 fits into the inner periphery of the bottom portion 122. By fitting the mounting shaft portion 31 into the inner periphery of the bottom portion 122, the case member 95 is positioned radially relative to the piston rod 25 and arranged coaxially. The bottom portion 122 has a plurality of passage holes 126 formed between the inner and outer peripheries, penetrating the bottom portion 122 in the axial direction of the bottom portion 122. The plurality of passage holes 126 are arranged at equal intervals around the periphery of the bottom portion 122, at positions equidistant from the center of the bottom portion 122. The case member 95 is oriented so that the bottom portion 122 is closer to the piston 21 than the cylindrical portion 124 in the axial direction and abuts against the disk 86. The outer diameter of the disk 86 is smaller than twice the shortest distance between the radial center of the case member 95 and the passage holes 126.

[0065] The intermediate curved portion 123 is annular and coaxial with the bottom portion 122, and a cross section of the plane including the central axis thereof has a curved shape that is convex radially outward and axially toward the bottom portion 122. The cylindrical portion 124 is coaxial with the bottom portion 122 and the intermediate curved portion 123.

[0066] The case member 95 is thicker than one of the discs 84, 85 and has a cylindrical shape with a bottom, making it more rigid than the discs 84, 85. Therefore, the case member 95 abuts against the main valve 91, which is made up of multiple discs 84, 85, and restricts deformation of the main valve 91 in the opening direction beyond a specified level.

[0067] The valve member 96 is a flexible, perforated, circular metal plate. The valve member 96 has an inner annular portion 127 on the radially inner side and an outer conical portion 128 on the radially outer side. The inner annular portion 127 is a perforated, circular, flat plate with a constant radial width around its entire circumference. The outer conical portion 128 has a constant radial width around its entire circumference and is a conical cylinder that extends radially outward and axially to one side from the outer peripheral edge of the inner annular portion 127. The valve member 96 is a disc spring. The valve member 96 is formed by stamping and bending a single sheet of plate material using a press molding method.

[0068] The outer diameter of the outer conical portion 128 of the valve member 96, i.e., the outer diameter of the valve member 96, is smaller than the inner diameter of the cylindrical portion 124 of the case member 95. The valve member 96 is in a state where the inner annular portion 127 abuts against the bottom portion 122 of the case member 95 and the outer conical portion 128 extends axially away from the bottom portion 122. In this state, the valve member 96 is positioned radially relative to the piston rod 25 by fitting the mounting shaft portion 31 into the inner peripheral side of the inner annular portion 127. The cylindrical portion 124 of the case member 95 is disposed radially outward of the valve member 96.

[0069] The valve member 96 has a hole 129 formed between the inner periphery and the outer periphery of the inner annular portion 127. The hole 129 penetrates the valve member 96 in the thickness direction (axial direction). The inner annular portion 127 has a plurality of holes 129 formed at intervals in the circumferential direction thereof. The hole 129 has an arc shape that is long in the circumferential direction of the inner annular portion 127. When the inner annular portion 127 of the valve member 96 abuts against the bottom portion 122 of the case member 95, the hole 129 aligns with the passage hole 126 of the bottom portion 122 in the radial direction of the case member 95 and the valve member 96. Therefore, the passages in the plurality of holes 129 communicate with the passages in the plurality of passage holes 126.

[0070] The disc 97 has a constant radial width around its entire circumference, and its outer diameter is smaller than twice the distance from the radial center of the valve member 96 to the inner end of the hole 129. Therefore, the disc 97 does not block or narrow the passages within the multiple hole 129. The disc 97 is thicker than the thickness of the inner annular portion 127 of the valve member 96, i.e., the plate thickness of the valve member 96.

[0071] The inner annular portion 127 of the valve member 96 is clamped in the axial direction by the bottom portion 122 of the case member 95 and the disc 97 , and is thereby fixed to the piston rod 25 .

[0072] The flexible disk 100 has a constant radial width around its entire circumference and is flexible. The outer diameter of the flexible disk 100 is larger than the outer diameter of the valve member 96 and smaller than the inner diameter of the cylindrical portion 124 of the case member 95. The flexible disk 100 has a thickness equal to the thickness of the valve member 96.

[0073] The flexible disk 100 is formed by punching out a single sheet of plate material using a press molding method. The flexible disk 100 has a flat plate shape in its natural state before being assembled to the piston rod 25. The flexible disk 100 has a passage hole 130 formed between its inner and outer peripheries, penetrating the flexible disk 100 in the thickness direction (axial direction) of the flexible disk 100. The flexible disk 100 has a plurality of passage holes 130 formed at equal intervals in the circumferential direction of the flexible disk 100. The diameter of the flexible disk 100 is twice the distance from the center to the inner end position of the passage hole 130 in the radial direction, which is larger than the outer diameter of the disk 97. Therefore, the passage hole 130 of the flexible disk 100 is not blocked or narrowed by the disk 97.

[0074] The valve member 96 has a circular outer peripheral edge of the outer conical portion 128, and this circular outer peripheral edge abuts over the entire circumference on the outer peripheral edge side of the flexible disk 100 outside the passage hole 130 in the radial direction.

[0075] The valve member 96 is disposed between the bottom 122 of the case member 95 and the flexible disk 100, with the disk 97 sandwiched between the valve member 96 and the flexible disk 100. Here, the axial length of the outer conical portion 128 of the valve member 96 in its natural state before being assembled to the piston rod 25 is longer than the thickness of the disk 97. Therefore, when the valve member 96 is assembled to the piston rod 25, the outer conical portion 128 abuts against the flexible disk 100 while bending to shorten its axial length. As a result, the valve member 96 is assembled so as to apply an axial load to the bottom 122 of the case member 95 and the flexible disk 100.

[0076] The disc 101 has a constant radial width over its entire circumference and is flexible. The disc 101 is flat in its natural state before being attached to the piston rod 25. The disc 101 has an outer diameter smaller than that of the flexible disc 100 and larger than twice the distance from the center of the flexible disc 100 in the radial direction to the outer ends of the passage holes 130. When the disc 101 comes into surface contact with the flexible disc 100 over its entire circumference, it closes all of the passage holes 130.

[0077] The outer diameter of the disk 102 is smaller than the outer diameter of the disk 101. The disk 102, together with the disk 97, clamps the inner peripheral sides of the flexible disk 100 and the disk 101 in the axial direction.

[0078] The disk 103 has a constant radial width around its entire circumference. The disk 103 has an outer diameter larger than that of the disk 101 and equal to that of the flexible disk 100. The disk 103 is thicker and more rigid than the flexible disk 100 and the disk 101. When the flexible disk 100 deforms, the disk 103 comes into contact with the flexible disk 100 to prevent further deformation of the flexible disk 100.

[0079] The closing member 109 is in the form of a perforated disk having a through hole 131 formed in the radial center thereof, which extends axially and penetrates through the thickness direction to insert the mounting shaft portion 31. The through hole 131 has a small diameter hole portion 132 on one axial side into which the mounting shaft portion 31 of the piston rod 25 is fitted, and a large diameter hole portion 133 on the other axial side which has a larger diameter than the small diameter hole portion 132.

[0080] Closing member 109 has an annular boss portion 134 at its axial end on the large diameter hole portion 133 side so as to surround large diameter hole portion 133. Closing member 109 also has an annular boss portion 138 at its axial end on the small diameter hole portion 132 side so as to surround small diameter hole portion 132. Closing member 109 has a perforated disk-shaped main body portion 135 between boss portion 134 and boss portion 138 in the axial direction.

[0081] The boss portion 134 protrudes to one side along the axial direction of the main body portion 135 from the inner peripheral edge portion on the large diameter hole portion 133 side of the axial direction of the main body portion 135. The boss portion 138 protrudes to the opposite side of the boss portion 134 along the axial direction of the main body portion 135 from the inner peripheral edge portion on the small diameter hole portion 132 side of the axial direction of the main body portion 135. The blocking member 109 abuts against the disk 103 at the boss portion 134, and abuts against the nut 119 at the boss portion 138.

[0082] A passage groove 139 is formed in the boss portion 134, radially crossing the boss portion 134. The passage groove 139 is formed by being recessed in the axial direction of the blocking member 109 from the tip end face of the boss portion 134 on the side opposite to the main body portion 135. The passage in the passage groove 139 communicates with the passage in the large diameter hole portion 133.

[0083] The closing member 109 is disposed so that the passage groove 139 and the passage within the large diameter hole portion 133 are aligned with the annular groove 33c of the piston rod 25 in the axial direction of the piston rod 25. This allows the passage within the passage groove 139 of the closing member 109 to communicate with the passages within the axial groove 33a, the annular groove 33b, and the annular groove 33c of the piston rod 25 via the passage within the large diameter hole portion 133, even without circumferentially aligning the phase of the closing member 109 with the piston rod 25. The passages within the axial groove 33a, the annular groove 33b, and the annular groove 33c of the piston rod 25, i.e., the passage within the passage cutout 33, the passage within the large diameter hole portion 59a of the piston 21, and the passage within the large diameter hole portion 133 of the closing member 109, form an intermediate chamber 140.

[0084] The closing member 109 has an annular seal groove 141 recessed radially inward at the axially intermediate position of the outer periphery of the main body 135. An O-ring 108 is disposed in this seal groove 141. The closing member 109 is fitted into the cylindrical portion 124 at the outer periphery of the main body 135 with the boss portion 134 facing the bottom 122. By being provided in the case member 95 in this manner, the closing member 109 closes the opening side, which is part of the case member 95. In this state, the O-ring 108 seals the gap between the cylindrical portion 124 of the case member 95 and the closing member 109.

[0085] A lower-chamber-communicating reservoir chamber 149 (reservoir chamber) is formed surrounded by the valve member 96, the disk 97, the flexible disk 100, and the disk 101. This lower-chamber-communicating reservoir chamber 149 is constantly in communication with the passages in the multiple hole portions 129 of the valve member 96 and the passages in the multiple passage holes 126 in the bottom portion 122 of the case member 95.

[0086] An upper chamber communicating reservoir chamber 147 (reservoir chamber) is formed surrounded by the case member 95, the valve member 96, the flexible disk 100, the disks 101 to 103, and the closing member 109. The upper chamber communicating reservoir chamber 147 is constantly in communication with the intermediate chamber 140 via a passage in the passage groove 139 of the closing member 109.

[0087] The communication between the lower chamber communicating reservoir chamber 149 and the upper chamber communicating reservoir chamber 147 is blocked by the bottom 122 of the case member 95, the valve member 96, the flexible disk 100, and the disk 101.

[0088] As shown in Fig. 2, the annular closing member 109 and the bottomed cylindrical case member 95 are disposed in the lower chamber 23, which is one of the upper chamber 22 and the lower chamber 23. In this case, as shown in Fig. 3, the boss portion 138 of the closing member 109 is disposed on the lower chamber 23 side. The passage within the passage hole 126 in the bottom portion 122 of the case member 95 is constantly in communication with the lower chamber 23. Therefore, the lower-chamber-communicating storage chamber 149 is constantly in communication with the lower chamber 23 via the passage within the hole portion 129 of the valve member 96 and the passage within the passage hole 126 in the bottom portion 122 of the case member 95.

[0089] The upper chamber communicating reservoir chamber 147 is constantly connected to the upper chamber 22 shown in FIG. 2 via the passages in the passage groove 139 and the large diameter hole portion 133 of the blocking member 109, the passages in the annular groove 33c, the axial groove 33a and the annular groove 33b of the piston rod 25, the passages in the large diameter hole portion 59a of the piston 21, the orifice 62 of the piston 21 and the passages in the passage hole 38 of the piston 21.

[0090] 3 flexes in the axial direction, changing the volumes of the lower-chamber communicating reservoir 149 and the upper-chamber communicating reservoir 147. That is, flexing of the flexible disk 100 allows the lower-chamber communicating reservoir 149 and the upper-chamber communicating reservoir 147 to function as accumulators. The lower-chamber communicating reservoir 149 decreases in volume to absorb the increase in the volume of the upper-chamber communicating reservoir 147, thereby discharging the oil liquid L to the lower chamber 23, and increases in volume to absorb the decrease in the volume of the upper-chamber communicating reservoir 147, thereby allowing the oil liquid L to flow in from the lower chamber 23. Conversely, the upper-chamber communicating reservoir 147 decreases in volume to absorb the increase in the volume of the lower-chamber communicating reservoir 149, thereby discharging the oil liquid L to the upper chamber 22, and increases in volume to absorb the decrease in the volume of the lower-chamber communicating reservoir 149, thereby allowing the oil liquid L to flow in from the upper chamber 22. In this way, the deformation of the flexible disc 100 is prevented from being hindered by the oil liquid L in the upper chamber communicating reservoir chamber 147 and the lower chamber communicating reservoir chamber 149.

[0091] A second passage 172 that can communicate between the upper chamber 22 and the lower chamber 23 is formed by the passage within the passage hole 38 of the piston 21, the orifice 62 of the piston 21, the passage within the large-diameter hole 59a of the piston 21, the passage within the passage notch 33 of the piston rod 25, and the passage within the large-diameter hole 133 of the closing member 109, the passage within the passage groove 139 of the closing member 109, the upper-chamber communicating reservoir chamber 147, the lower-chamber communicating reservoir chamber 149, the passage within the hole 129 of the valve member 96, and the passage within the passage hole 126 of the case member 95. The second passage 172 is provided in parallel with the first passage 72 and the first passage 92 shown in FIG. 2 and can communicate between the upper chamber 22 and the lower chamber 23. As shown in Figure 3, when the outer circumferential side of the flexible disk 100 abuts against the outer circumferential edge of the valve member 96 and the outer circumferential side of the inner annular portion 127 of the valve member 96 abuts against the bottom 122 of the case member 95, the second passage 172 closes an intermediate position thereof.

[0092] During the compression stroke, when the pressure in lower chamber communicating reservoir chamber 149 communicating with lower chamber 23 becomes higher by a predetermined value or more than the pressure in upper chamber communicating reservoir chamber 147 communicating with upper chamber 22, the outer circumferential side of flexible disc 100 deforms so as to move axially away from the outer circumferential edge of valve member 96, thereby connecting lower chamber communicating reservoir chamber 149 and upper chamber communicating reservoir chamber 147 and connecting lower chamber 23 and upper chamber 22 via second passage 172. When second passage 172 becomes compression-side second passage 172(A) in this way, it includes a passage between the outer circumferential side of flexible disc 100 and the outer circumferential edge of valve member 96.

[0093] The valve member 96, flexible disc 100, and disc 101 are provided in a second passage 172(A) and form a compression-side second damping force generating mechanism 173 that opens and closes the second passage 172(A) to suppress the flow of oil L from the lower chamber 23 to the upper chamber 22 through the second passage 172(A) and generates a damping force. In the second damping force generating mechanism 173, the outer periphery of the opening and closing flexible disc 100 and the outer periphery of the valve member 96 form a communication mechanism 174 that controls communication between the lower-chamber communication reservoir chamber 149 and the upper-chamber communication reservoir chamber 147. The second damping force generating mechanism 173 is disposed separately from the first damping force generating mechanism 42 shown in FIG. 2, which generates a damping force during the same compression stroke. The damping force of the second damping force generating mechanism 173 can be adjusted by changing and adjusting the thickness of the disc 97.

[0094] During the extension stroke, when the pressure in upper chamber communicating reservoir 147, which is in communication with upper chamber 22, becomes higher by a predetermined value or more than the pressure in lower chamber communicating reservoir 149, which is in communication with lower chamber 23, the outer circumferential side of inner annular portion 127 of valve member 96 deforms so as to move axially away from bottom 122 of case member 95, thereby connecting upper chamber communicating reservoir 147 and lower chamber communicating reservoir 149 and connecting upper chamber 22 and lower chamber 23 via second passage 172. When second passage 172 becomes extension-side second passage 172(B) in this way, it includes a passage between the outer circumferential side of inner annular portion 127 of valve member 96 and bottom 122 of case member 95.

[0095] The valve member 96 and the bottom 122 of the case member 95 are provided in the second passage 172(B) and open and close the second passage 172(B). This constitutes an extension-side second damping force generation mechanism 183 that generates a damping force by suppressing the flow of oil L from the upper chamber 22 to the lower chamber 23 through the second passage 172(B). In the second damping force generation mechanism 183, the outer periphery of the inner annular portion 127 of the valve member 96 that opens and closes and the bottom 122 of the case member 95 form a communication mechanism 184 that controls communication between the upper-chamber communication reservoir chamber 147 and the lower-chamber communication reservoir chamber 149. The second damping force generation mechanism 183 is disposed separately from the first damping force generation mechanism 41, which generates a damping force during the same extension stroke. The damping force of the second damping force generation mechanism 183 can be adjusted by changing and adjusting the thickness of the disc 97.

[0096] In the compression-side second passage 172(A), when the communication mechanism 174 of the second damping force generation mechanism 173 is in an open state, the orifice 62 of the piston 21 has the narrowest flow path cross-sectional area among the portions with fixed flow path cross-sectional areas, and the flow path cross-sectional area is narrower than that on its upstream and downstream sides. The orifice 62 is disposed downstream of the second damping force generation mechanism 173 in the flow of the oil liquid L when the communication mechanism 174 of the second damping force generation mechanism 173 is open and the oil liquid L flows from the lower chamber 23 to the upper chamber 22 in the second passage 172(A). Note that the orifice 62 may also be disposed upstream of the second damping force generation mechanism 173 in the flow of the oil liquid L when the communication mechanism 174 of the second damping force generation mechanism 173 is open and the oil liquid L flows from the lower chamber 23 to the upper chamber 22 in the second passage 172(A).

[0097] In the extension-side second passage 172(B), when the communication mechanism 184 of the second damping force generation mechanism 183 is in an open state, the orifice 62 of the piston 21 has the narrowest flow path cross-sectional area among the portions with fixed flow path cross-sectional areas, and the flow path cross-sectional area is narrower than that on its upstream and downstream sides. The orifice 62 is disposed upstream of the second damping force generation mechanism 183 in the flow of the oil liquid L when the communication mechanism 184 of the second damping force generation mechanism 183 is open and the oil liquid L flows from the upper chamber 22 to the lower chamber 23 in the second passage 172(B). Note that the orifice 62 may also be disposed downstream of the second damping force generation mechanism 183 in the flow of the oil liquid L when the communication mechanism 184 of the second damping force generation mechanism 183 is open and the oil liquid L flows from the upper chamber 22 to the lower chamber 23 in the second passage 172(B).

[0098] In the second passage 172, when the outer periphery of the flexible disc 100 abuts against the outer periphery of the valve member 96 and the outer periphery of the inner annular portion 127 of the valve member 96 abuts against the bottom 122 of the case member 95, i.e., when the communicating mechanisms 174, 184 are closed, no fixed orifice is formed that communicates between the upper chamber 22 and the lower chamber 23. In other words, when the outer periphery of the flexible disc 100 abuts against the outer periphery of the valve member 96 over the entire circumference, i.e., when the communicating mechanism 174 is closed, the compression-side second damping force generating mechanism 173 does not communicate between the lower chamber 23 and the upper chamber 22. In addition, the extension-side second damping force generating mechanism 183 does not communicate between the upper chamber 22 and the lower chamber 23 when the outer periphery of the inner annular portion 127 of the valve member 96 abuts against the bottom 122 of the case member 95 over the entire circumference, i.e., when the communicating mechanism 184 is closed. In other words, the second passage 172 does not have a fixed orifice that constantly connects the upper chamber 22 and the lower chamber 23, and is not a passage that constantly connects the upper chamber 22 and the lower chamber 23.

[0099] The second passage 172(A) on the compression side, which can communicate between the lower chamber 23 and the upper chamber 22, is arranged in parallel with the first passage 72 shown in Fig. 2, which is also a compression side passage which can communicate between the lower chamber 23 and the upper chamber 22. The first damping force generating mechanism 42 is provided in the first passage 72, and the second damping force generating mechanism 173 is provided in the second passage 172(A) shown in Fig. 3. Therefore, the first damping force generating mechanism 42 shown in Fig. 2 and the second damping force generating mechanism 173 shown in Fig. 3, which are both on the compression side, are arranged in parallel.

[0100] The second extension passage 172(B), which can communicate between the upper chamber 22 and the lower chamber 23, is parallel to the first passage 92, which is also an extension passage which can communicate between the upper chamber 22 and the lower chamber 23. The first damping force generating mechanism 41 is provided in the first passage 92, and the second damping force generating mechanism 183 is provided in the second passage 172(B). Therefore, the first damping force generating mechanism 41 and the second damping force generating mechanism 183, both of which are on the extension side, are arranged in parallel.

[0101] The bottom 122 of the case member 95, the valve member 96, the disk 97, the flexible disk 100, the disk 101, and the lower chamber communicating reservoir 149 constitute a lower chamber volume variable mechanism 185 (volume variable mechanism) that can change the volume of the lower chamber communicating reservoir 149. The lower chamber volume variable mechanism 185 is provided in the second passage 172 that includes the lower chamber communicating reservoir 149, and the lower chamber volume variable mechanism 185 changes the volume of this lower chamber communicating reservoir 149.

[0102] The lower chamber volume variable mechanism 185 is operated by the movement of the piston 21 during the compression stroke causing oil liquid L, which is a working fluid, to flow into the second passage 172 from the lower chamber 23, which is located upstream within the inner tube 2 of the cylinder 4, and is provided with a lower chamber communication reservoir 149 that stores the oil liquid L from the upstream lower chamber 23. The communication mechanism 174 is provided in the lower chamber volume variable mechanism 185, and when the lower chamber volume variable mechanism 185 is displaced by a predetermined amount or more, communicates between the lower chamber communication reservoir 149 and the upper chamber 22, which is located downstream of the cylinder 4. The lower chamber volume variable mechanism 185 has a case member 95 that covers the lower chamber volume variable mechanism 185, a valve member 96 that has one radial end fixed and the other radial end formed as a free end and abuts against the case member 95, and a flexible disk 100 that is formed to abut against the valve member 96. The communication mechanism 174 communicates the lower chamber communication reservoir 149 with the upper chamber 22 located downstream of the cylinder 4 when the valve member 96 is separated from the flexible disk 100 .

[0103] The lower chamber volume variable mechanism 185 changes the volume of the lower chamber communication reservoir 149 so as to increase it by deforming and moving the flexible disk 100 and the disk 101 together away from the bottom 122. At that time, if the flexible disk 100 is kept in contact with the valve member 96 over the entire circumference, i.e., if the communication mechanism 174 is kept in a closed state, the space between the flexible disk 100 and the outer conical portion 128 of the valve member 96 is closed. In other words, if the flexible disk 100 is kept in contact with the valve member 96 over the entire circumference when it deforms away from the bottom 122, the volume of the lower chamber communication reservoir 149 increases and the volume of the upper chamber communication reservoir 147 decreases while maintaining a blocked state between the lower chamber communication reservoir 149 and the upper chamber communication reservoir 147.

[0104] Furthermore, lower chamber volume variable mechanism 185 changes the volume of lower chamber communication reservoir 149 by deforming and moving flexible disk 100 and disk 101 together so as to approach bottom 122. Even at this time, flexible disk 100 remains in contact with valve member 96 as a whole, and the space between flexible disk 100 and outer conical portion 128 of valve member 96 is blocked.

[0105] Case member 95, valve member 96, flexible disk 100, disk 101, disks 102 and 103, closing member 109, and upper chamber communicating reservoir 147 constitute upper chamber volume variable mechanism 186 (volume variable mechanism) that can change the volume of upper chamber communicating reservoir 147. Upper chamber volume variable mechanism 186 is provided in second passage 172 that includes upper chamber communicating reservoir 147. Upper chamber volume variable mechanism 186 changes the volume of upper chamber communicating reservoir 147.

[0106] The upper chamber volume variable mechanism 186 is operated by the movement of the piston 21 during the extension stroke, causing hydraulic fluid L to flow from the upper chamber 22, which is located upstream within the inner tube 2 of the cylinder 4, into the second passage 172, and is provided with an upper chamber communication reservoir 147 that stores the hydraulic fluid L from the upper chamber 22, which is located upstream. The communication mechanism 184 is provided in the upper chamber volume variable mechanism 186, and communicates the upper chamber communication reservoir 147 with the lower chamber 23, which is located downstream of the cylinder 4, when the upper chamber volume variable mechanism 186 is displaced by a predetermined amount or more. The upper chamber volume variable mechanism 186 has a case member 95 that covers the upper chamber volume variable mechanism 186, a valve member 96 that has one radial end fixed and the other radial end formed as a free end and abuts against the case member 95, and a flexible disk 100 that is formed to abut against the valve member 96. The communication mechanism 184 communicates the upper chamber communication reservoir 147 with the lower chamber 23 located downstream of the cylinder 4 by separating the valve member 96 from the case member 95 .

[0107] As the piston 21 moves toward the compression side, the valve member 96 communicates between the upper chamber 22, which is on the downstream side of the cylinder 4, and a lower-chamber communicating reservoir 149 that communicates with the lower chamber 23, which is one of the upper chamber 22 and the lower chamber 23 in the cylinder 4. As the piston 21 moves in the extension direction, the valve member 96 communicates between the lower chamber 23, which is on the downstream side of the cylinder 4, and an upper-chamber communicating reservoir 147 that communicates with the upper chamber 22, which is the other of the upper chamber 22 and the lower chamber 23 in the cylinder 4. Thus, the valve member 96 communicates between the upper chamber 22 or the lower chamber 23, which is on the downstream side of the cylinder 4 depending on the movement direction of the piston 21, and the lower-chamber communicating reservoir 149 that communicates with the lower chamber 23, which is one of the upper chamber 22 and the lower chamber 23 in the cylinder 4, or the upper-chamber communicating reservoir 147 that communicates with the upper chamber 22, which is the other of the upper chamber 22 and the lower chamber 23 in the cylinder 4.

[0108] Upper chamber volume variable mechanism 186 changes the volume of upper chamber communication reservoir chamber 147 by deforming and moving flexible disk 100 and disk 101 together so as to move away from disk 103. At that time, if the state in which the outer periphery of inner annular portion 127 of valve member 96 abuts against bottom portion 122 of case member 95, i.e., the closed state of communication mechanism 184, is maintained, upper chamber volume variable mechanism 186 increases the volume of upper chamber communication reservoir chamber 147 and decreases the volume of lower chamber communication reservoir chamber 149 while maintaining the state in which upper chamber communication reservoir chamber 147 and lower chamber communication reservoir chamber 149 are blocked.

[0109] Additionally, upper chamber volume variable mechanism 186 changes the volume of upper chamber communication reservoir chamber 147 by deforming and moving flexible disk 100 and disk 101 so that they approach disk 103, thereby reducing the volume of upper chamber communication reservoir chamber 147. Even at this time, valve member 96 maintains a state in which the outer circumferential side of inner annular portion 127 abuts against bottom portion 122 of case member 95, and the space between valve member 96 and bottom portion 122 of case member 95 is blocked.

[0110] The flexible disc 100, disc 101, and valve member 96 are shared by the lower chamber volume variable mechanism 185 and the upper chamber volume variable mechanism 186. The lower chamber volume variable mechanism 185, which includes the lower chamber communicating reservoir chamber 149, and the upper chamber volume variable mechanism 186, which includes the upper chamber communicating reservoir chamber 147, form an accumulator 190 that stores hydraulic oil L as a working fluid. The accumulator 190 is provided on the piston rod 25. In the accumulator 190, the upper chamber volume variable mechanism 186 changes the volume before the second damping force generation mechanism 183 opens during the extension stroke, and the lower chamber volume variable mechanism 185 changes the volume before the second damping force generation mechanism 173 opens during the compression stroke.

[0111] 2, when main valve 71 is assembled to piston rod 25, its inner circumferential side is clamped between discs 63 and 66, and its outer circumferential side abuts against valve seat portion 50 of piston 21. When main valve 91 is assembled to piston rod 25, its inner circumferential side is clamped between discs 83 and 86, and its outer circumferential side abuts against valve seat portion 48 of piston 21.

[0112] 3, when the flexible disc 100 is assembled to the piston rod 25, the inner peripheral side of the flexible disc 100, together with the disc 101, is clamped to the discs 97 and 102, and the outer peripheral side abuts against the outer conical portion 128 of the valve member 96. At this time, the flexible disc 100 elastically deforms in a tapered manner such that the portion radially outward of the disc 97 moves away from the bottom 122 in the axial direction as it moves radially outward. At this time, the valve member 96 abuts against the flexible disc 100 over the entire circumference while elastically deforming its outer conical portion 128. In this state, the disc 101 also elastically deforms in a tapered manner, following the shape of the flexible disc 100, such that the portion radially outward of the disc 102 moves away from the bottom 122 in the axial direction as it moves radially outward.

[0113] The above configuration is shown in a hydraulic circuit diagram as shown in Figure 4. As shown in Figure 4, a compression-side first damping force generating mechanism 42 is provided in a first passage 72 connecting the upper chamber 22 and the lower chamber 23. A rebound-side first damping force generating mechanism 41 is provided in a first passage 92 connecting the lower chamber 23 and the upper chamber 22. Fixed orifices 64b and 84b constantly communicate the upper chamber 22 and the lower chamber 23. A second passage 172 connecting the upper chamber 22 and the lower chamber 23 is provided with an accumulator 190 having an orifice 62 on the upper chamber 22 side, an intermediate chamber 140 on the lower chamber 23 side of the orifice 62, and an upper-chamber-communicating reservoir chamber 147 and a lower-chamber-communicating reservoir chamber 149 on the lower chamber 23 side of the intermediate chamber 140.

[0114] 1, the valve body 10 is formed with fluid passages 251 and 252 that penetrate in the axial direction. The fluid passages 251, 252 are capable of communicating between the lower chamber 23 and the reservoir chamber 5. The base valve 12 has a compression-side damping force generating mechanism 255 that can open and close the fluid passage 251 on the axial side of the bottom member 9 of the valve body 10. The base valve 12 also has an extension-side damping force generating mechanism 256 that can open and close the fluid passage 252 on the axial side of the valve body 10 opposite the bottom member 9.

[0115] When the piston rod 25 moves toward the compression side and the piston 21 moves in a direction that narrows the lower chamber 23, causing the pressure in the lower chamber 23 to become higher than the pressure in the reservoir chamber 5 by a predetermined value or more, the damping force generating mechanism 255 opens the fluid passage 251 to allow the oil L in the lower chamber 23 to flow into the reservoir chamber 5, generating a damping force. In other words, when the piston rod 25 moves toward the compression side and moves the piston 21, the oil L flows out of the fluid passage 251 into the reservoir chamber 5. The damping force generating mechanism 255 is a compression-side damping force generating mechanism. This damping force generating mechanism 255 does not obstruct the flow of the oil L in the fluid passage 252.

[0116] When the piston rod 25 moves toward the extension side and the piston 21 moves toward the upper chamber 22, causing the pressure in the lower chamber 23 to drop below the pressure in the reservoir chamber 5, the damping force generating mechanism 256 opens the fluid passage 252 to allow the hydraulic fluid L in the reservoir chamber 5 to flow into the lower chamber 23, generating a damping force. In other words, when the piston rod 25 moves toward the extension side and moves the piston 21, the hydraulic fluid L flows out of the fluid passage 252 into the lower chamber 23. The damping force generating mechanism 256 is an extension-side damping force generating mechanism. This damping force generating mechanism 256 does not obstruct the flow of the hydraulic fluid L in the fluid passage 251. The damping force generating mechanism 256 may also be a suction valve that allows the hydraulic fluid L to flow from the reservoir chamber 5 into the lower chamber 23 without generating any substantial damping force.

[0117] <Activation> Of the first damping force generating mechanism 41 and second damping force generating mechanism 183 shown in Figure 3, both of which are on the extension side, the main valve 91 of the first damping force generating mechanism 41 has greater rigidity and a higher valve opening pressure than the valve member 96 of the second damping force generating mechanism 183. Therefore, during the extension stroke, in the extremely low speed region where the piston speed, which is the axial movement speed of the piston 21, is slower than a predetermined value, the first damping force generating mechanism 41 remains closed and the second damping force generating mechanism 183 opens. Furthermore, in the normal speed region where the piston speed is equal to or greater than this predetermined value, both the first damping force generating mechanism 41 and the second damping force generating mechanism 183 open. The valve member 96 is an extremely low speed valve that opens in the extremely low speed region of the piston speed to generate damping force.

[0118] During the extension stroke, the piston 21 moves toward the upper chamber 22 shown in FIG. 2, increasing the pressure in the upper chamber 22 and decreasing the pressure in the lower chamber 23. During the extension stroke when the piston speed is equal to or less than a first predetermined value, both the first damping force generating mechanism 41 and the second damping force generating mechanism 183 are in a closed state, and the oil L in the upper chamber 22 flows to the lower chamber 23 via the passages in the multiple passage holes 38 and annular groove 55 of the piston 21, the fixed orifice 84b provided in the disk 84 of the main valve 91, the fixed orifice 64b provided in the disk 64 of the main valve 71, and the passages in the annular groove 56 and multiple passage holes 39 of the piston 21. This generates a damping force with orifice characteristics (the damping force is approximately proportional to the square of the piston speed). Therefore, the damping force characteristic relative to the piston speed is such that the rate of increase in the damping force increases relatively rapidly as the piston speed increases.

[0119] During the extension stroke when the piston speed is greater than the first predetermined value and less than a second predetermined value greater than the first predetermined value, oil L from the upper chamber 22 flows into the upper chamber communicating reservoir 147 via the passage in the passage hole 38 of the piston 21, the orifice 62, the passage in the large-diameter hole portion 59a of the piston 21, the passage in the passage notch 33 of the piston rod 25, and the passage in the large-diameter hole portion 133 of the closing member 109, and the passage in the passage groove 139 of the closing member 109. This increases the pressure in the upper chamber communicating reservoir 147. Therefore, in the upper chamber volume variable mechanism 186 shown in FIG. 3 , before the second damping force generating mechanism 183 opens, a portion of the flexible disc 100 radially inward from the position where it abuts against the outer conical portion 128 of the valve member 96 bends toward the bottom portion 122, thereby increasing the volume of the upper chamber communicating reservoir 147. As a result, the upper chamber volume variable mechanism 186 suppresses an increase in pressure in the upper chamber communication reservoir chamber 147. At this time, the flexible disk 100 bends and moves toward the bottom 122, and the lower chamber volume variable mechanism 185 reduces the volume of the lower chamber communication reservoir chamber 149.

[0120] Here, during the extension stroke when a low-frequency input (large-amplitude vibration) occurs, which is the piston frequency of the axial movement of the piston 21, the amount of oil L flowing from the upper chamber 22 to the upper-chamber communicating reservoir 147 increases, causing the flexible disc 100 to deform significantly. As the amount of deformation of the flexible disc 100 increases, the reaction force due to the support rigidity of the clamped inner periphery increases, limiting the amount of deformation. This causes the upper-chamber communicating reservoir 147 to increase in pressure. As a result, the pressure in the second passage 172 increases to a state where the second damping force generating mechanism 183 opens. In a region where the piston speed is higher than a first predetermined value and in an extremely low-speed region that is higher than the first predetermined value but lower than a second predetermined value, the first damping force generating mechanism 41 remains closed and the second damping force generating mechanism 183 opens.

[0121] That is, the outer circumferential side of the inner annular portion 127 of the valve member 96 moves away from the bottom portion 122 of the case member 95 in the axial direction, opening the communication mechanism 184 and connecting the upper chamber 22 and the lower chamber 23 through the extension-side second passage 172(B). Thus, the oil L in the upper chamber 22 flows into the lower chamber 23 via the passage in the passage hole 38 of the piston 21, the orifice 62, the passage in the large-diameter hole portion 59a of the piston 21, the passage in the passage cutout portion 33 of the piston rod 25, and the passage in the large-diameter hole portion 133 of the closing member 109, the passage in the passage groove 139 of the closing member 109, the upper-chamber communicating reservoir chamber 147, the communication mechanism 184 in the open state, the lower-chamber communicating reservoir chamber 149, the passage in the hole portion 129 of the valve member 96, and the passage in the passage hole 126 of the bottom portion 122 of the case member 95. As a result, even in an extremely low-speed region where the piston speed is slower than the second predetermined value, a damping force with valve characteristics (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained. The flow of oil L at this time is indicated by arrow X1 in Figure 5(a) and by arrows X11 to X15 in Figure 6.

[0122] During the extension stroke when the piston speed is equal to or greater than the second predetermined value, the first damping force generating mechanism 41 opens, while the second damping force generating mechanism 183 remains open. That is, as described above, the outer circumferential side of the inner annular portion 127 of the valve member 96 moves axially away from the bottom portion 122 of the case member 95, allowing the hydraulic fluid L to flow from the upper chamber 22 to the lower chamber 23 in the extension-side second passage 172(B). At this time, the flow of the hydraulic fluid L is throttled by the orifice 62 provided downstream of the main valve 91 in the second passage 172(B), increasing the pressure applied to the main valve 91 and increasing the pressure difference. As a result, the main valve 91 lifts off the valve seat 48, allowing the hydraulic fluid L to flow from the upper chamber 22 to the lower chamber 23 in the extension-side first passage 92. Therefore, the oil liquid L in the upper chamber 22 flows into the lower chamber 23 through the passages in the multiple passage holes 38 and the annular groove 55, and the passage between the main valve 91 and the valve seat portion 48. The flow of the oil liquid L at this time is indicated by arrow X2 in Figure 5(a).

[0123] This allows the damping force to have valve characteristics (the damping force is approximately proportional to the piston speed) even in the normal speed region where the piston speed is equal to or greater than the second predetermined value. The rate of increase in the extension damping force relative to an increase in piston speed in the normal speed region is lower than the rate of increase in the extension damping force relative to an increase in piston speed in the extremely low speed region. In other words, the slope of the rate of increase in the extension damping force relative to an increase in piston speed in the normal speed region can be made gentler than in the extremely low speed region.

[0124] During the extension stroke when a high frequency input (small amplitude vibration) occurs in which a higher piston frequency than that during the low frequency input described above is input to the shock absorber 1, the amount of oil L that flows from the upper chamber 22 to the upper chamber communicating reservoir 147 is small. Therefore, deformation of the flexible disc 100 is small, and the upper chamber volume variable mechanism 186 can absorb the volume of oil L that flows into the upper chamber communicating reservoir 147 by the amount of deflection of the flexible disc 100, thereby reducing the pressure increase in the upper chamber communicating reservoir 147. Therefore, during the rise of the extremely low speed damping force, it is possible to achieve a state as if the flexible disc 100 were not present and the upper chamber communicating reservoir 147 were communicating with the lower chamber 23 via the lower chamber communicating reservoir 149, the passage in the hole 129 of the valve member 96, and the passage in the passage hole 126 in the bottom 122 of the case member 95, i.e., a state identical to that of a structure without the second damping force generating mechanism 183. Therefore, during the extension stroke when a high frequency input is applied, the rise of the extremely low speed damping force is gentler than when a low frequency input is applied.

[0125] Here, during the extension stroke, the damping force characteristics of the damping force generating mechanism 256 are also taken into account.

[0126] Of the first damping force generating mechanism 42 and second damping force generating mechanism 173 shown in Figure 2, both of which are on the compression side, the main valve 71 of the first damping force generating mechanism 42 has greater rigidity and a higher valve opening pressure than the flexible disc 100 of the second damping force generating mechanism 173. Therefore, during the compression stroke, in the extremely low speed region where the piston speed is slower than a predetermined value, the first damping force generating mechanism 42 remains closed and the second damping force generating mechanism 173 opens, and in the normal speed region where the piston speed is equal to or greater than this predetermined value, both the first damping force generating mechanism 42 and the second damping force generating mechanism 173 open. The flexible disc 100 is an extremely low speed valve that opens in the extremely low speed region of the piston speed to generate damping force.

[0127] During the compression stroke, the piston 21 moves toward the lower chamber 23, increasing the pressure in the lower chamber 23 and decreasing the pressure in the upper chamber 22. During the compression stroke when the piston speed is equal to or less than a third predetermined value, both the first damping force generating mechanism 42 and the second damping force generating mechanism 173 are in a closed state, and the oil L in the lower chamber 23 flows to the upper chamber 22 via the passages in the multiple passage holes 39 and annular groove 56 of the piston 21, the fixed orifice 64b provided in the disk 64 of the main valve 71, the fixed orifice 84b provided in the disk 84 of the main valve 91, and the passages in the annular groove 55 and multiple passage holes 38 of the piston 21. This generates a damping force with orifice characteristics (the damping force is approximately proportional to the square of the piston speed). Therefore, the damping force characteristic relative to the piston speed is such that the rate of increase in the damping force increases relatively rapidly as the piston speed increases.

[0128] During the compression stroke when the piston speed is greater than the third predetermined value and less than a fourth predetermined value greater than the third predetermined value, the oil L in the lower chamber 23 flows into the lower chamber communicating reservoir 149 through the passage in the passage hole 126 of the case member 95 and the passage in the hole 129 of the valve member 96 shown in FIG. 3 . This causes the pressure in the lower chamber communicating reservoir 149 to increase. Therefore, the lower chamber volume variable mechanism 185 causes the flexible disc 100 to bend toward the disc 103, increasing the capacity of the lower chamber communicating reservoir 149, before the second damping force generating mechanism 173 opens. This causes the lower chamber volume variable mechanism 185 to suppress the increase in pressure in the lower chamber communicating reservoir 149. At this time, the disc 101 deforms in accordance with the flexible disc 100. At this time, the flexible disk 100 bends and moves toward the disk 103 side, and the upper chamber volume variable mechanism 186 reduces the volume of the upper chamber communication reservoir chamber 147 .

[0129] During the compression stroke when a low-frequency input (large-amplitude vibration) is applied, the amount of oil L flowing from the lower chamber 23 to the lower-chamber communicating reservoir 149 increases, causing the flexible disc 100 to deform significantly. As the amount of deformation of the flexible disc 100 increases, the reaction force due to the support rigidity of the clamped inner periphery increases, limiting the amount of deformation. This increases the pressure in the lower-chamber communicating reservoir 149. As a result, the pressure in the second passage 172(A) increases to a state where the second damping force generating mechanism 173 opens. In a region where the piston speed is higher than the third predetermined value and in an extremely low speed region that is higher than the third predetermined value but lower than a fourth predetermined value, the first damping force generating mechanism 42 remains closed and the second damping force generating mechanism 173 opens.

[0130] That is, the flexible disc 100 separates from the outer conical portion 128 of the valve member 96, the communication mechanism 174 opens, and the second passage 172(A) on the compression side connects the lower chamber 23 to the upper chamber 22. Thus, the oil L in the lower chamber 23 flows into the upper chamber 22 via the passage in the passage hole 126 in the bottom 122 of the case member 95, the passage in the hole 129 of the valve member 96, the lower-chamber communicating reservoir 149, the passage between the flexible disc 100 and the outer conical portion 128 of the valve member 96, the upper-chamber communicating reservoir 147, the passage in the passage groove 139 of the closing member 109, the passage in the large-diameter hole 133 of the closing member 109, the passage in the passage notch 33 of the piston rod 25, and the passage in the large-diameter hole 59a of the piston 21, the orifice 62, and the passage in the passage hole 38 of the piston 21. As a result, even in an extremely low-speed region where the piston speed is slower than the fourth predetermined value, a damping force with valve characteristics (a characteristic in which the damping force is approximately proportional to the piston speed) can be obtained. The flow of oil L at this time is indicated by arrow X3 in Figure 5(b) and by arrows X31 to X35 in Figure 6.

[0131] During the compression stroke when the piston speed is equal to or greater than the fourth predetermined value, the first damping force generating mechanism 42 opens while the second damping force generating mechanism 173 remains open. That is, as described above, the flexible disc 100 leaves the outer conical portion 128 of the valve member 96, and hydraulic oil L flows from the lower chamber 23 to the upper chamber 22 through the compression-side second passage 172(A). At this time, the flow of hydraulic oil L is throttled by the orifice 62 provided in the second passage 172(A) downstream of the communicating mechanism 174, so that the pressure applied to the main valve 71 increases and the pressure difference increases, causing the main valve 71 to leave the valve seat portion 50, and hydraulic oil L flows from the lower chamber 23 to the upper chamber 22 through the compression-side first passage 72. Therefore, the oil liquid L in the lower chamber 23 flows into the upper chamber 22 through the passages in the multiple passage holes 39 and the annular groove 56, and the passage between the main valve 71 and the valve seat portion 50. The flow of the oil liquid L at this time is indicated by arrow X4 in Figure 5(b).

[0132] This allows a damping force with valve characteristics (damping force is approximately proportional to piston speed) to be obtained even in the normal speed region where the piston speed is equal to or greater than the fourth predetermined value. The rate of increase in the compression damping force with respect to an increase in piston speed in the normal speed region is lower than the rate of increase in the compression damping force with respect to an increase in piston speed in the extremely low speed region. In other words, the slope of the rate of increase in the extension damping force with respect to an increase in piston speed in the normal speed region can be made gentler than in the extremely low speed region.

[0133] During the compression stroke when a high frequency input (small amplitude vibration) occurs in which a higher piston frequency than that during the low frequency input described above is input to the shock absorber 1, the amount of oil liquid L that flows from the lower chamber 23 to the lower chamber communicating reservoir 149 is small. Therefore, the deformation of the flexible disc 100 is small. Therefore, the deformation of the flexible disc 100 is small, and the lower chamber volume variable mechanism 185 can absorb the volume of oil liquid L that flows into the lower chamber communicating reservoir 149 by the amount of deflection of the flexible disc 100, thereby reducing the pressure increase in the lower chamber communicating reservoir 149. Therefore, during the rise of the extremely low speed damping force, it is possible to achieve a state as if the flexible disc 100 were not present and the lower chamber communicating reservoir 149 were constantly communicating with the upper chamber communicating reservoir 147, i.e., a state that is the same as a structure without the second damping force generation mechanism 173. Therefore, during the compression stroke when a high frequency input is applied, the rise of the extremely low speed damping force is gentler than when a low frequency input is applied.

[0134] Here, during the compression stroke, the damping force characteristics of the damping force generating mechanism 255 are also taken into account.

[0135] The reference example shown in the above-mentioned Patent Document 1 describes a shock absorber having two damping force generating mechanisms that open in the same stroke. These damping force generating mechanisms are configured so that one low-speed damping force generating mechanism generates a damping force with valve characteristics when the piston speed is slow and the piston frequency is low, while the other high-speed damping force generating mechanism generates a damping force with valve characteristics when the piston speed is faster and the piston frequency is higher than that of the low-speed damping force generating mechanism. However, there is a demand for space-saving and cost-reducing shock absorbers.

[0136] The shock absorber 1 of this embodiment is provided with a lower chamber volume variable mechanism 185 equipped with a lower chamber communicating reservoir 149 that operates when oil liquid L flows from the lower chamber 23, which is upstream inside the inner tube 2 of the cylinder 4, into the second passage 172 due to the movement of the piston 21 during the compression stroke, and stores the oil liquid L in the lower chamber 23, and a communication mechanism 174 that communicates the lower chamber communicating reservoir 149 with the upper chamber 22, which is downstream of the cylinder 4, when the lower chamber volume variable mechanism 185 is displaced by a predetermined amount or more. Furthermore, the shock absorber 1 is provided with an upper chamber volume variable mechanism 186 that is provided with an upper chamber communication reservoir chamber 147 that operates when oil L flows from the upper chamber 22, which is upstream inside the inner tube 2 of the cylinder 4, into the second passage 172 due to the movement of the piston 21 during the extension stroke, and that stores the oil L in the upper chamber 22, and a communication mechanism 184 that communicates the upper chamber communication reservoir chamber 147 with the lower chamber 23, which is downstream of the cylinder 4, when the upper chamber volume variable mechanism 186 is displaced by a predetermined amount or more. Therefore, the shock absorber 1 can be designed to save space and reduce costs.

[0137] In the shock absorber 1, the lower chamber volume variable mechanism 185 includes a case member 95 that covers the lower chamber volume variable mechanism 185, a valve member 96 that has one radial end fixed and the other radial end formed as a free end and that abuts against the case member 95, and a flexible disk 100 that is formed to abut against the valve member 96. The compression-side communication mechanism 174 communicates between the lower chamber communication reservoir 149 and the upper chamber 22 that is downstream of the cylinder 4 when the valve member 96 moves away from the flexible disk 100. In the shock absorber 1, the upper chamber volume variable mechanism 186 includes a case member 95 that covers the upper chamber volume variable mechanism 186, a valve member 96 that has one radial end fixed and the other radial end formed as a free end and that abuts against the case member 95, and a flexible disk 100 that is formed to abut against the valve member 96. Then, when the valve member 96 separates from the case member 95, the extension-side communication mechanism 184 communicates between the upper chamber communication reservoir chamber 147 and the lower chamber 23 located downstream of the cylinder 4. Therefore, in the shock absorber 1, the single valve member 96 constitutes the compression-side communication mechanism 174 and the extension-side communication mechanism 184, so the number of parts can be reduced, making it possible to further save space and reduce costs.

[0138] In shock absorber 1, valve member 96 communicates between upper chamber 22 or lower chamber 23, which is downstream of cylinder 4 depending on the direction of movement of piston 21, and lower chamber communicating reservoir 149, which communicates with lower chamber 23, which is one of upper chamber 22 and lower chamber 23 in cylinder 4, or upper chamber communicating reservoir 147, which communicates with upper chamber 22, which is the other of upper chamber 22 and lower chamber 23 in cylinder 4. Therefore, in shock absorber 1, one valve member 96 constitutes compression-side communicating mechanism 174 and extension-side communicating mechanism 184, making it possible to reduce the number of parts, further saving space and reducing costs.

[0139] The shock absorber 1 is assembled such that the valve member 96 is provided between the case member 95 and the flexible disk 100 and applies an axial load to the case member 95 and the flexible disk 100. Therefore, in the shock absorber 1, the valve member 96 is applied with a set load, and therefore does not open even with slight deformation due to pressure. As a result, the valve member 96 in the shock absorber 1 can effectively vary the volumes of the lower chamber communicating storage chamber 149 and the upper chamber communicating storage chamber 147 while keeping them disconnected from each other.

[0140] In the shock absorber 1, the closing member 109 that closes a part of the case member 95 forms the second passage 172. Therefore, the shock absorber 1 can reduce the number of parts, and it is possible to achieve further space saving and cost reduction.

[0141] In the shock absorber 1, the closing member 109 that closes a part of the case member 95 abuts against the nut 119, so that the number of parts can be reduced, and it is possible to achieve further space saving and further cost reduction. [Explanation of symbols]

[0142] 1... shock absorber, 4... cylinder, 21... piston, 22... upper chamber (chamber), 23... lower chamber (chamber), 25... piston rod, 41, 42... first damping force generating mechanism, 72, 92... first passage, 95... case member, 96... valve member, 100... flexible disc (plate member), 109... blocking member, 147... upper chamber communicating storage chamber (storage chamber), 149... lower chamber communicating storage chamber (storage chamber), 172, 172(A), 172(B)... second passage, 173, 183... second damping force generating mechanism, 174, 184... communication mechanism, 185... lower chamber volume variable mechanism (volume variable mechanism), 186... upper chamber volume variable mechanism (volume variable mechanism), L... oil (working fluid).

Claims

1. a cylinder containing a working fluid; a piston slidably provided in the cylinder and dividing the interior of the cylinder into two chambers; a piston rod having one end connected to the piston and the other end extending to the outside of the cylinder; a first passage through which the working fluid flows from an upstream chamber of the cylinder to a downstream chamber as the piston moves; a second passage provided in parallel with the first passage; a first damping force generating mechanism that is provided in the first passage and operates when the working fluid flows through the first passage due to movement of the piston, thereby generating a damping force; a volume variable mechanism provided in the second passage, the volume variable mechanism being operated by the working fluid flowing from an upstream chamber in the cylinder into the second passage as the piston moves, and including a storage chamber for storing the working fluid in the upstream chamber; A communication mechanism provided in the volume variable mechanism, which communicates the storage chamber with a chamber downstream of the cylinder when the volume variable mechanism is displaced by a predetermined amount or more; A buffer having

2. 2. The shock absorber according to claim 1, the volume variable mechanism includes a case member that covers the volume variable mechanism, a valve member that has one radial end fixed and the other radial end formed as a free end and that abuts against the case member, and a plate member that is formed to abut against the valve member, The communication mechanism is a shock absorber that communicates the storage chamber with a chamber downstream of the cylinder by separating the valve member from the case member or the plate member.

3. 3. The shock absorber according to claim 2, The storage chamber is formed by a first storage chamber communicating with one of the two chambers in the cylinder and a second storage chamber communicating with the other of the two chambers in the cylinder, The valve member is a shock absorber that connects a chamber downstream of the cylinder with the first storage chamber or the second storage chamber depending on the direction of movement of the piston.

4. 3. The shock absorber according to claim 2, The valve member is provided between the case member and the plate member, and is assembled so as to apply an axial load to the case member and the plate member.

5. 3. The shock absorber according to claim 2, The case member is provided with a closing member that forms the second passage and closes a portion of the case member.

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