Buffer

Abstract

To provide a buffer that can restrain degradation of a seal ring and can exhibit stable seal performance.SOLUTION: A buffer D according to the present invention comprises a cylinder 1, a rod guide 2 fitted to an inner periphery of an end part of the cylinder 1, a piston rod 3 movably inserted into the cylinder 1, a piston 4 connected to the piston rod 3, and a seal member S stacked on the rod guide 2, and into which the piston rod 3 is inserted. The seal member S comprises: an annular seal case 7 comprising an annular concave part 7a in an inner periphery; a seal ring 8 comprising a base part 8a and a lip 8b, and housed in the annular concave part 7a; an annular seal holder 9 stacked on the base part 8a on the side of the rod guide, housed in the annular concave part 7a, and for supporting an outer periphery of the seal ring 8 to restrain diameter enlargement of the lip 8b; and a stopper 10 fitted to the seal case 7, and for preventing the seal holder 9 and the seal ring 8 from falling off.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] A shock absorber is used, for example, interposed between a vehicle body and wheels of a vehicle, and suppresses vibrations of the vehicle body and wheels with a damping force generated during expansion and contraction.

[0003] A shock absorber includes a cylinder, an annular rod guide fitted to the inner periphery of an end portion of the cylinder, a piston rod inserted through the inner periphery of the rod guide and movably inserted into the cylinder, and a piston connected to the piston rod and inserted into the cylinder, which divides the inside of the cylinder into an extension chamber and a compression chamber filled with hydraulic oil. In addition, it is provided with a seal unit that seals the outer periphery of the piston rod in order to prevent leakage of hydraulic oil from the inside of the cylinder (see, for example, Patent Document 1).

[0004] Specifically, the seal unit is laminated on the atmosphere side of the rod guide, and includes an annular seal holding member having a seal accommodating portion formed by a recess having a large diameter in the middle of the inner diameter on the rod guide side, a seal member accommodated on the back side of the seal accommodating portion for sealing the outer periphery of the piston rod, and an annular seal holder accommodated on the front side of the seal accommodating portion for supporting the outer periphery of the seal member and suppressing the expansion of the seal member. The shock absorber configured in this way can obtain good sealing performance because the seal member is backed up by the seal holder and compresses the piston rod.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the process of assembling a conventional shock absorber, after assembling a seal member and a seal holder to a seal holding member in advance to form a seal unit, a dust seal, the seal unit, and a rod guide are sequentially attached to the outer periphery of the piston rod, and then a piston is attached to the tip of the piston rod to assemble a piston rod assembly. The piston rod assembly thus completed is inserted into the cylinder and attached to the cylinder by caulking the end of the cylinder.

[0007] However, since the seal member and the seal holder in the seal unit are only inserted into the seal accommodating portion of the seal holding member, when assembling the piston rod assembly or inserting the piston rod assembly into the cylinder, etc., the seal member and the seal holder may fall off from the seal accommodating portion to the outside. If the assembly of the shock absorber is completed without noticing this, there is a possibility that the seal member and the seal holder are assembled in a state where they are not accommodated in the seal accommodating portion of the seal holding member in the correct posture. of In such a situation, it may be pointed out that the seal member cannot tighten the entire circumference of the piston rod with a uniform tightening force, and stable sealing performance (seal performance) cannot be obtained.

[0008] Therefore, an object of the present invention is to provide a shock absorber that can suppress deterioration of the seal ring and exhibit stable seal performance.

[0009] SUMMARY OF THE INVENTION In order to solve the above problems, a shock absorber of the present invention includes a cylinder, an annular rod guide fitted to the inner periphery of the end of the cylinder, a piston rod inserted through the inner periphery of the rod guide and movably inserted into the cylinder, a piston connected to the piston rod and inserted into the cylinder to partition the inside of the cylinder into an extension chamber and a compression chamber filled with a working fluid. Means for Solving the Problems

[0010] To solve the above-described problems, the shock absorber of the present invention includes a cylinder, an annular rod guide fitted to the inner periphery of the end of the cylinder, a piston rod inserted through the inner periphery of the rod guide and movably inserted into the cylinder, a piston connected to the piston rod and inserted into the cylinder to partition the inside of the cylinder into an extension chamber and a compression chamber filled with a working fluid.independent of the rod guide and A seal member that is annular, laminated on the anti-piston side of the rod guide, fitted to the inner periphery of the end of the cylinder, and through which the piston rod is inserted on the inner periphery. The seal member includes an annular seal case having an annular recess on the inner periphery on the rod guide side, an annular base portion, and an annular lip that rises from the inner periphery of the base portion toward the rod guide side and is in sliding contact with the outer periphery of the piston rod, and is housed in the annular recess. A seal ring, an annular seal holder that is laminated on the rod guide side of the base of the seal ring, is housed in the annular recess, supports the outer periphery of the lip, and suppresses the diameter expansion of the lip, and a stopper that is attached to the seal case and abuts against the rod guide side surface of the seal holder to prevent the seal holder and the seal ring from falling off.

[0011] According to the shock absorber configured in this way, since the stopper prevents the seal ring and the seal holder from falling out of the annular recess of the seal holder, even if vibration acts on the seal member during the conveyance of the piston rod assembly with the seal member assembled to the piston rod, the seal ring and the seal holder can be maintained in a state of being assembled to the seal case in the correct posture. also, the stopper may be sandwiched between the rod guide and the seal case.

[0012] Further, the seal case has an annular socket on the outer periphery on the rod guide side, and the stopper has an annular plate that is fitted to the inner periphery of the socket, abuts against the seal holder, and has an inner diameter larger than the outer diameter of the piston rod, and a fixing member that is attached to the socket and fixes the plate to the seal case. According to the shock absorber configured in this way, the plate can be fixed to the seal case at an appropriate position to prevent the seal ring and the seal holder from coming off, and when the extension side chamber is at high pressure during the extension operation, the pressure in the extension side chamber can be applied to the seal ring to effectively prevent the leakage of the working fluid from the cylinder.

[0013] Furthermore, the plate may include an inner peripheral portion that faces the seal holder and forms an annular gap therebetween, an outer peripheral portion that is continuous with the outer periphery of the inner peripheral portion, abuts against the seal holder, and is fitted to the inner periphery of the socket, one or more through holes that penetrate the inner peripheral portion, and a chamfered portion provided on the outer periphery of the outer peripheral portion on the rod guide side. According to the shock absorber configured in this way, since a gap is formed between the plate and the seal holder, interference between the plate and the lip in the seal ring is avoided, and an excessive pressing force is not applied to the lip, and deterioration due to wear of the seal ring can be suppressed. Also, according to the shock absorber configured in this way, the seal holder can be supported by the inner peripheral portion of the plate, and the pressing force of the lip can be maintained to exhibit good sealing performance. And furthermore, according to the shock absorber configured in this way, since the plate is provided with through holes, leakage of the working fluid from the cylinder can be effectively prevented even during the extension operation. In addition, according to the shock absorber configured in this way, since the plate is provided with a chamfered portion, incorrect assembly can be prevented.

[0014] The fixing member has an annular main body portion that abuts against the rod guide side surface of the plate, and three or more arms provided on the outer periphery of the main body portion for gripping the outer periphery of the socket. The main body portion has an inner diameter larger than the outer diameter of the piston rod and is provided with one or more notches formed to open from the inner periphery toward the outer periphery. The plate may have an inner diameter equal to or larger than the diameter of the circumscribed circle that contacts the tips of the notches. Further, the socket has a portion on its inner periphery with a diameter larger than the inner diameter of the open end. The fixing member has an annular main body portion that abuts against the rod guide side surface of the plate, and a plurality of claws provided on the outer periphery of the main body portion for entering the larger-diameter portion of the socket. The main body portion has an inner diameter larger than the outer diameter of the piston rod and is provided with one or more notches formed to open from the inner periphery toward the outer periphery. The plate may have an inner diameter equal to or larger than the diameter of the circumscribed circle that contacts the tips of the notches. Also, the socket has an annular groove provided on its inner periphery and at least one or more longitudinal grooves formed axially along from the open end on the inner periphery and communicating with the annular groove. The fixing member has an annular main body portion that abuts against the rod guide side surface of the plate, and one or more protrusions provided at positions corresponding to the longitudinal grooves on the outer periphery of the main body portion and insertable into the longitudinal grooves of the socket and fitted into the annular groove. The main body portion has an inner diameter larger than the outer diameter of the piston rod and is provided with a plurality of notches formed to open from the inner periphery toward the outer periphery. The plate may have an inner diameter equal to or larger than the diameter of the circumscribed circle that contacts the tips of the notches. According to the shock absorber configured in this way, the seal member can be easily assembled manually without using tools, and since the plate can be made thinner, the overall axial length of the seal member can be shortened, making it even easier to ensure the stroke length.

[0015] Further, the stopper may include an annular plate that abuts against the rod guide side surface of the seal holder and the seal case and has an inner diameter larger than the outer diameter of the piston rod, and a fixing member that grips the outer periphery of the seal case and fixes the plate to the seal case. According to the shock absorber configured in this way, since the structure in which the outer periphery of the seal case is gripped and the fixing member is fixed to the seal case is adopted, the plate can be made into a thin annular ring and the axial length of the seal member can be shortened, so that it becomes easier to secure a longer stroke.

Advantages of the Invention

[0016] As described above, according to the shock absorber of the present invention, deterioration of the seal ring can be suppressed and stable seal performance can be exhibited.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2, a shock absorber D in one embodiment includes a cylinder 1, an annular rod guide 2 provided at an end of the cylinder 1, a piston rod 3 inserted through the inner circumference of the rod guide 2 and movably inserted into the cylinder 1, a piston 4 connected to the piston rod 3 and inserted into the cylinder 1 to partition the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2 filled with a working fluid, and an annular seal member S laminated on the side of the rod guide 2 opposite to the piston and fitted to the inner circumference of the end of the cylinder 1 with the piston rod 3 inserted through the inner circumference. And in the case of this shock absorber D, it is interposed and used between the vehicle body and the wheel in a vehicle (not shown) to suppress the vibration of the vehicle body and the wheel.

[0019] Hereinafter, each part of the shock absorber D will be described in detail. As shown in FIG. 1, an annular rod guide 2 is attached to the upper end of the cylinder 1 in FIG. 1. And a piston rod 3 is inserted through the inner circumference of the rod guide 2, and the rod guide 2 guides the relative movement in the vertical direction (axial direction of the piston rod 3 with respect to the cylinder 1) in FIG. 1.

[0020] The rod guide 2 is configured to include an annular main body 2a that fits inside the cylinder 1, a cylindrical bush 2b that is mounted on the inner circumference of the main body 2a and is in sliding contact with the outer circumference of the piston rod 3, an annular convex portion 2c that protrudes from the radial intermediate portion at the upper end in FIG. 2 on the side opposite to the piston of the main body 2a toward the side opposite to the piston, an annular concave portion 2d provided from the outer circumference of the convex portion 2c to the outer circumference of the main body 2a, an annular groove 2e provided on the inner circumference side of the convex portion 2c of the main body 2a, a through hole 2f that penetrates from the piston side end of the main body 2a to the end of the convex portion 2c, and a notch 2g provided in the convex portion 2c that communicates from the inner circumference of the convex portion 2c to the through hole 2f.

[0021] When the rod guide 2 configured as described above is inserted into the cylinder 1, its movement downward in FIG. 1 toward the piston 4 side is restricted by the C-ring 5 mounted on the inner circumference of the cylinder 1. On the atmosphere side, which is the side opposite to the piston of the rod guide 2, a seal member S and a dust seal member 6 are laminated. The rod guide 2, the seal member S, and the dust seal member 6 are clamped between the caulked portion 1a formed in the cylinder 1 by caulking the pipe end of the cylinder 1 and the aforementioned C-ring 5 and fixed to the cylinder 1.

[0022] Subsequently, the piston rod 3 is inserted through the inner circumference of the rod guide 2 as described above. The piston rod 3 has a small-diameter portion 3a at its tip, to which the piston 4, the extension-side damping valve 11, and the compression-side damping valve 12 are mounted. A piston nut 14 is screwed onto the tip of the small-diameter portion 3a, and the piston 4, the extension-side damping valve 11, and the compression-side damping valve 12 are fixed to the piston rod 3 by the piston nut 14.

[0023] The piston 4 is mounted at the tip of the piston rod 3 as described above and is slidably inserted into the cylinder 1. The cylinder 1 is partitioned into an extension-side chamber R1 above the piston 4 in FIG. 1 facing the rod guide 2 and a compression-side chamber R2 below the piston 4 in FIG. 1. The extension-side chamber R1 and the compression-side chamber R2 are filled with a working fluid such as hydraulic oil. Note that the working fluid may be, in addition to hydraulic oil, for example, a liquid such as water or an aqueous solution, an electro-viscous fluid, a magneto-viscous fluid, or even a gas.

[0024] The piston 4 is provided with an extension passage 4a and a compression passage 4b that communicate the extension chamber R1 and the compression chamber R2. The extension damping valve 11 is laminated below the piston 4 in FIG. 1 and opens and closes the lower end of the extension passage 4a in FIG. 1, and the compression damping valve 12 is laminated above the piston 4 in FIG. 1 and opens and closes the upper end of the compression passage 4b in FIG. 1. These extension damping valve 11 and compression damping valve 12 are both laminated leaf valves composed of a plurality of laminated leaf valves, but are not limited to this as long as they are valves capable of generating damping force. And the extension damping valve 11 opens and gives resistance to the flow of hydraulic oil passing through the extension passage 4a toward the compression chamber R2 that expands from the extension chamber R1 compressed by the piston 4 during the extension stroke of the shock absorber D when the piston rod 3 moves upward in FIG. 1 with respect to the cylinder 1. The compression damping valve 12 opens and gives resistance to the flow of hydraulic oil passing through the compression passage 4b toward the extension chamber R1 that expands from the compression chamber R2 compressed by the piston 4 during the contraction stroke of the shock absorber D when the piston rod 3 moves downward in FIG. 1 with respect to the cylinder 1.

[0025] Note that the lower end of the cylinder 1 in FIG. 1 is closed, and although not shown in detail, it is provided with a bracket for connecting the shock absorber D to the vehicle body or the wheel side. Also, a free piston F that partitions an air chamber G is slidably inserted into the cylinder 1 below the compression chamber R2.

[0026] And when the shock absorber D extends, resistance is given by the extension damping valve 11 to the flow of hydraulic oil from the compressed extension chamber R1 toward the expanding compression chamber R2, and the shock absorber D generates a damping force that hinders the extension. Also, during the extension stroke of the shock absorber D, since the piston rod 3 withdraws from the cylinder 1, the free piston F moves upward in FIG. 1 by an amount corresponding to the volume of the piston rod 3 withdrawing from the cylinder 1 to expand the air chamber G, and compensation for the volume of the piston rod 3 withdrawing from the cylinder 1 is performed.

[0027] Conversely, when the shock absorber D contracts, the pressure-side damping valve 12 resists the flow of hydraulic oil from the compressed pressure-side chamber R2 to the expanding extension-side chamber R1. Further, when the shock absorber D contracts, since the piston rod 3 enters the cylinder 1, the free piston F moves downward in FIG. 1 by an amount corresponding to the volume by which the piston rod 3 enters the cylinder 1, reducing the air chamber G, and compensation is made for the volume by which the piston rod 3 enters the cylinder 1. Therefore, when the shock absorber D is in the contraction stroke, the pressure-side damping valve 12 resists the flow of the hydraulic oil as described above, so the shock absorber D generates a pressure-side damping force that hinders contraction.

[0028] Note that a bypass passage that bypasses the extension-side damping valve 11 and the pressure-side damping valve 12 and connects the extension-side chamber R1 and the pressure-side chamber R2, and a damping force adjustment valve provided in the bypass passage may be provided in the shock absorber D so that the extension-side damping force and the pressure-side damping force of the shock absorber D can be adjusted up and down. Further, when the working fluid of the shock absorber D is an electro-viscous fluid, a magneto-viscous fluid, or an electro-magneto-viscous fluid, an electric field generation source that applies an electric field or a magnetic field generation source that applies a magnetic field is used as a damping force generation source in the passage connecting the extension-side chamber R1 and the pressure-side chamber R2 instead of the extension-side damping valve 11 and the pressure-side damping valve 12. Therefore, the configuration related to the generation of the damping force of the shock absorber D can be arbitrarily designed and changed.

[0029] Note that, as described above, the compensation for the volume of the piston rod 3 entering and leaving the cylinder 1 is performed by providing a free piston F in the cylinder 1 to form an air chamber G, but a reservoir tank communicating with the pressure-side chamber R2 may be provided outside the cylinder 1 to perform the volume compensation. In that case, a base valve that resists the flow of hydraulic oil from the pressure-side chamber R2 to the reservoir tank may be provided between the pressure-side chamber R2 and the reservoir tank so that the base valve contributes to the generation of the pressure-side damping force.

[0030] Next, the seal member S is annular and is laminated on the atmosphere side on the opposite side of the piston of the rod guide 2 and is fitted to the inner periphery of the end of the cylinder 1, and the piston rod 3 is inserted through the inner periphery.

[0031] Specifically, as shown in FIGS. 2 and 3, the seal member S includes an annular seal case 7 having an annular recess 7a on the inner circumference of the rod guide 2 side, a seal ring 8 housed in the annular recess 7a, an annular seal holder 9 housed in the annular recess 7a and supporting the outer circumference of the lip 8b of the seal ring 8, and a stopper 10 attached to the seal case 7 to prevent the seal holder 9 and the seal ring 8 from falling off.

[0032] The seal case 7 is annular and includes an annular recess 7a provided on the inner circumference of the end on the rod guide 2 side, which is the lower end in FIG. 2, and an annular socket 7b provided on the outer circumference of the lower end in FIG. 2. The annular recess 7a is a stepped annular recess with an enlarged inner diameter in the middle on the rod guide 2 side, and is configured to include a small-diameter recess 7a1 on the back side and a large-diameter recess 7a2 on the front side when viewed from the rod guide 2 side.

[0033] Further, the socket 7b rises from the outer circumference of the end on the rod guide 2 side of the seal case 7 toward the rod guide 2 side and has an annular groove 7b1 on the inner circumference. Furthermore, the seal case 7 has an annular recess 7c on the outer circumference of the upper end in FIG. 2, which is the anti-rod guide side.

[0034] The seal ring 8 is formed of synthetic resin or rubber and includes an annular base 8a and an annular lip 8b that rises from the inner circumference of the base 8a toward the rod guide 2 side and slidably contacts the outer circumference of the piston rod 3. It is housed in the annular recess 7a in the seal case 7. In this embodiment, the seal ring 8 is formed of fluororubber. More specifically, the thickness, which is the axial height of the base 8a in the seal ring 8, is longer than the axial length of the small-diameter recess 7a1 in the annular recess 7a, and the outer diameter of the base 8a is slightly smaller so as to be fitted to the inner circumference of the small-diameter recess 7a1.

[0035] When the seal ring 8 is housed in the annular recess 7a of the seal case 7, the seal ring 8 is housed in the annular recess 7a with its base 8a inserted into the small-diameter recess 7a1. The inner diameter of the lip 8b is smaller than the outer diameter of the piston rod 3 and has an interference fit. When the seal ring 8 is mounted on the outer periphery of the piston rod 3, the lip 8b presses the outer periphery of the piston rod 3 with a predetermined pressing force and is in sliding contact with the outer periphery of the piston rod 3 to seal the outer periphery of the piston rod 3.

[0036] In this embodiment, the seal holder 9 is formed of acrylonitrile-butadiene rubber, is annular, and is housed in the annular recess 7a in the seal case 7. More specifically, the seal holder 9 includes an annular holding portion 9a that protrudes radially inward from the inner circumference on the rod guide 2 side. Further, the axial height of the seal holder 9 is equal to the axial height of the large-diameter recess 7a2 in the annular recess 7a, and the outer diameter is approximately equal to the inner diameter of the large-diameter recess 7a2. Then, the seal holder 9 is fitted into the large-diameter recess 7a2 in the annular recess 7a and housed in the annular recess 7a, and the end face on the anti-rod guide side is brought into contact with the end face on the rod guide side of the base 8a of the seal ring 8. Also, the inner diameter of the holding portion 9a of the seal holder 9 is smaller than the outer diameter at the location where the holding portion 9a of the lip 8b abuts when the piston rod 3 is inserted into the inner circumferential side. When the seal holder 9 is fitted into the large-diameter recess 7a2, the holding portion 9a supports the outer circumference of the lip 8b. The holding portion 9a supports the outer circumference of the lip 8b when the piston rod 3 is inserted through the inner circumference of the lip 8b, suppressing the expansion of the diameter of the lip 8b and bringing the lip 8b into close contact with the outer circumference of the piston rod 3. In this way, the seal holder 9 supports the lip 8b of the seal ring 8 from the outer circumferential side, suppresses the expansion of the diameter of the lip 8b fitted to the outer circumference of the piston rod 3, and stabilizes the surface pressure at the portion where the lip 8b contacts the piston rod 3. Since the seal ring 8 is formed of fluororubber, it can withstand high temperatures well and exhibits good sealing performance, but it is somewhat inferior in terms of cold resistance. However, in the shock absorber D of this embodiment, the seal ring 8 is backed up by the seal holder 9 formed of acrylonitrile-butadiene rubber having excellent cold resistance, so good sealing performance can be obtained in a wide temperature range from high temperature to low temperature. In this way, if the seal ring 8 is formed of a synthetic resin or rubber material that exhibits good sealing performance even at high temperatures, and the seal holder 9 is formed of a synthetic resin or rubber material having excellent cold resistance, good sealing performance can be obtained in a wide temperature range from high temperature to low temperature. However, the seal ring 8 and the seal holder 9 may be formed of the same synthetic resin or rubber.

[0037] The stopper 10 includes an annular plate 10a that fits into the inner circumference of the socket 7b and abuts against the seal holder 9, and a C-shaped retaining ring 10b that is attached to the socket 7b and serves as a fixing member for fixing the plate 10a to the seal case 7.

[0038] The plate 10a has an inner diameter larger than the outer diameter of the piston rod 3, forming an annular gap H1 between the plate 10a and the piston rod 3, and an inner peripheral portion 10a1 that forms an annular gap H2 between the plate 10a and the seal holder 9 facing the seal holder 9. An outer peripheral portion 10a2 that is continuous with the outer circumference of the inner peripheral portion 10a1, abuts against the seal holder 9, and fits into the inner circumference of the socket 7b. Six through holes 10a3 are provided at equal intervals on the same circumference of the middle portion of the inner peripheral portion 10a1 and penetrate the inner peripheral portion 10a1. And a chamfered portion 10a4 provided on the outer circumference of the outer peripheral portion 10a2 on the rod guide side.

[0039] The plate 10a configured in this way has its outer circumference fitted into the inner circumference of the socket 7b and is assembled to the seal case 7, and is fixed to the seal case 7 by the retaining ring 10b attached to the annular groove 7b1 provided on the inner circumference of the socket 7b. When the plate 10a is inserted into the socket 7b in the correct orientation, the chamfered portion 10a4 faces the annular groove 7b1 of the socket 7b, allowing the retaining ring 10b to be attached to the annular groove 7b1. That is, the length from the upper end of the plate 10a to the chamfered portion 10a4 is equal to or slightly shorter than the length from the contact surface of the seal case 7 with respect to the plate 10a to the annular groove 7b1 of the socket 7b. Therefore, when the plate 10a is fitted into the socket 7b with the front and back (up and down in FIG. 2) reversed, the outer circumference of the plate 10a faces the annular groove 7b1 and the attachment of the retaining ring 10b to the annular groove 7b1 becomes impossible.

[0040] When the plate 10a is fixed to the seal case 7, the seal holder 9 that abuts against the outer peripheral portion 10a2 of the plate 10a cannot come out of the large-diameter recess 7a2 in the annular recess 7a. And the seal ring 8 whose base 8a abuts against the seal holder 9 also cannot come out of the small-diameter recess 7a1 in the annular recess 7a. Therefore, when the stopper 10 composed of the plate 10a and the retaining ring 10b is attached to the seal case 7, the seal ring 8 and the seal holder 9 are integrated in a state where their detachment from the annular recess 7a of the seal case 7 is prevented. Note that the seal ring 8 is sandwiched between the seal holder 9 and the seal case 7 while the base 8a is axially compressed, so it biases the seal holder 9 toward the rod guide side from the seal case 7 but is fixed by the stopper 10 and thus does not fall off from the seal case 7.

[0041] And as described above, when the seal ring 8, the seal holder 9, and the stopper 10 are assembled to the seal case 7, the seal case 7, the seal ring 8, the seal holder 9, and the stopper 10 are integrated to form a seal member S which is a seal assembly.

[0042] A dust seal member 6 is laminated on the atmosphere side which is the side opposite to the piston side of the seal member S. The dust seal member 6 includes a core metal 6a which is an annular plate, an annular dust seal 6b which is integrated with the inner periphery on the atmosphere side which is the side opposite to the rod guide side of the core metal 6a and slidably contacts the outer periphery of the piston rod 3, and an annular outer periphery seal 6c which is integrated with the outer periphery on the rod guide side of the core metal 6a.

[0043] And when the dust seal member 6 is inserted into the cylinder 1 with the core metal 6a laminated on the end of the seal case 7 on the side opposite to the rod guide side in the seal member S, the outer periphery seal 6c is accommodated in a compressed state in the recess 7c of the seal case 7 and closely contacts the recess 7c of the seal case 7 and the inner periphery of the cylinder 1 to seal between the seal member S and the cylinder 1. Also, the dust seal member 6 slidably contacts the dust seal 6b with the outer periphery of the piston rod 3 to prevent the intrusion of dust and water such as dust and mud from around the outer periphery of the piston rod 3 into the cylinder 1.

[0044] The shock absorber D configured as described above is assembled according to the procedure described below. First, as described above, the seal ring 8, the seal holder 9, and the stopper 10 are assembled to the seal case 7 to assemble the seal member S.

[0045] Subsequently, the piston rod 3 is inserted in order from the tip side through the dust seal member 6, the seal member S, and the inner circumference of the rod guide 2, and the dust seal member 6, the seal member S, and the rod guide 2 are assembled to the piston rod 3.

[0046] Finally, the compression-side damping valve 12, the piston 4, and the extension-side damping valve 11 are sequentially assembled to the small-diameter portion 3a at the tip of the piston rod 3 and fixed to the piston rod 3 with the piston nut 14.

[0047] In this way, the piston 4, the extension-side damping valve 11, the compression-side damping valve 12, the rod guide 2, the seal member S, and the dust seal member 6 are assembled to the piston rod 3 as described above to obtain a piston rod assembly.

[0048] Subsequently, the piston rod assembly is inserted into the cylinder 1 from the piston 4 side. When the piston 4 and the compression-side damping valve 12 are completely accommodated in the cylinder 1, the C-ring 5 is attached to the inner circumference of the open end of the cylinder 1. Then, the piston rod assembly is further inserted into the cylinder 1 so that the rod guide 2 abuts against the C-ring 5, and the rod guide 2, the seal member S, and the dust seal member 6 are accommodated in the cylinder 1 in a stacked state.

[0049] While abutting the rod guide 2 against the C-ring 5, the rod guide 2, the seal member S, and the dust seal member 6 are accommodated in the cylinder 1 in a stacked state, and then the open end of the cylinder 1 is clamped by caulking, and the rod guide 2, the seal member S, and the dust seal member 6 are clamped between the caulking portion 1a and the C-ring 5 and fixed to the cylinder 1. Note that the injection of the working fluid into the extension chamber R1 and the compression chamber R2 may be performed in the process of inserting the piston rod assembly into the cylinder 1, or may be performed after this process and before the caulking process of the cylinder 1. Further, the injection of the gas into the air chamber G is performed, for example, from the lower end of the cylinder 1 after the assembly of the piston rod assembly to the cylinder 1, and the attachment process of the bracket to the lower end of the cylinder 1 is performed after the gas injection. Note that the assembly process of the damper D is an example and can be changed.

[0050] In the damper D assembled in this way, the seal member S includes an annular seal case 7 having an annular recess 7a on the inner periphery on the rod guide side, an annular base portion 8a, and an annular lip 8b that rises from the inner periphery of the base portion 8a toward the rod guide side and is in sliding contact with the outer periphery of the piston rod 3, and is accommodated in the annular recess 7a. A seal ring 8, an annular seal holder 9 that is laminated on the rod guide side of the base portion 8a of the seal ring 8 and is accommodated in the annular recess 7a and supports the outer periphery of the seal ring 8 to suppress the diameter expansion of the lip 8b, and a stopper 10 that is attached to the seal case 7 and abuts against the rod guide side surface of the seal holder 9 to prevent the seal holder 9 and the seal ring 8 from falling off.

[0051] Therefore, when assembling the seal member S on the outer periphery of the piston rod 3 to assemble the piston rod assembly or when inserting the piston rod assembly into the cylinder 1, the seal ring 8 and the seal holder 9 do not fall off from the seal case 7 and are maintained in a state of being accommodated in the annular recess 7a in the correct assembled posture.

[0052] Even when the piston rod assembly is assembled to the cylinder 1, the seal ring 8 and the seal holder 9 in the seal member S are assembled in a state of being correctly housed in the annular recess 7a of the seal case 7.

[0053] Therefore, the seal ring 8 is positioned at an appropriate position with respect to the piston rod 3, is in sliding contact with the outer periphery of the piston rod 3, and can compress the entire circumference of the piston rod 3 with a uniform pressing force. Even when the piston rod 3 moves up and down, the shock absorber D can exhibit stable sealing performance.

[0054] As described above, the seal member S is fixed to the cylinder 1 by being sandwiched between the caulking portion 1a of the cylinder 1 and the C-ring 5 together with the rod guide 2 and the dust seal member 6. At that time, since the socket 7b is housed in the recess 2d on the outer periphery of the rod guide 2, the plate 10a abuts against the convex portion 2c of the rod guide 2 and is fixed to the cylinder 1 while being pressed by the axial force received from the caulking portion 1a with respect to the seal case 7. Since the plate 10a is in contact with the outer periphery of the seal holder 9, the axial force is also applied to the seal holder 9, and even if a force acts to expand the lip 8b of the seal ring 8 and push out the seal holder 9 from the large-diameter recess 7a2, the seal holder 9 does not drop out of the large-diameter recess 7a2. The annular recess 7a may be formed as an annular recess with a constant inner diameter without the inner diameter expanding in the middle, but if the annular recess 7a includes a small-diameter recess 7a1 in which the base 8a of the seal ring 8 is housed and a large-diameter recess 7a2 in which the seal holder 9 is housed, the axial force received from the plate 10a does not excessively compress the base 8a of the seal ring 8, and the seal ring 8 can be protected.

[0055] Also, the inner diameter of the plate 10a in the stopper 10 is larger than the outer diameter of the piston rod 3. Although the plate 10a does not interfere with the piston rod 3, the inner peripheral portion 10a1 faces the seal holder 9 with a gap H2 therebetween. And as described above, the plate 10a is pressed by the axial force and fixed to the cylinder 1. Therefore, the lip 8b of piston rod 3 toEven if the seal holder 9 is deformed by the insertion of [[ID=]] so as to float from the seal case 7, the seal holder 9 can be supported and the sealing performance of the piston rod 3 by the lip 8b can be maintained. Further, even if the inner periphery of the seal holder 9 abuts on the plate 10a due to such deformation of the seal holder 9, the clearance H2 is always maintained in communication with the extending chamber R1 through the through hole 2f of the rod guide 2 by the through hole 10a3 provided in the inner peripheral portion 10a1 of the plate 10a. Therefore, the high pressure in the extending chamber R1 compressed during the extension operation of the shock absorber D can act on the seal holder 9 to increase the clamping force for clamping the piston rod 3 of the lip 8b in the seal ring 8. Also, the high pressure in the extending chamber R1 can act on the lip 8b through the annular clearance H1 between the plate 10a and the piston rod 3. Therefore, even during the extension operation of the shock absorber D when the extending chamber R1 becomes high pressure, the pressure in the extending chamber R1 can act on the seal ring 8 and the seal holder 9 to effectively prevent the leakage of the working fluid from the cylinder 1. Note that the number of the through holes 10a3 provided in the plate 10a may be one or more and can be arbitrarily set.

[0056] Also, if the working fluid contains contaminants such as cutting chips generated during the machining of the shock absorber D, the working fluid containing contaminants may be fed into the gap between the plate 10a and the rod guide 2 through the through hole 2f during the extension operation of the shock absorber D. In such a case, the contaminants can be prevented from being taken into the annular groove 2e of the rod guide 2 and returning to the extending chamber R1 and the compression chamber R2, and the contaminants can be recovered from the extending chamber R1 and the compression chamber R2 by the shock absorber D repeatedly performing the expansion and contraction operations to purify the working oil in the extending chamber R1 and the compression chamber R2.

[0057] As described above, the shock absorber D of the present embodiment includes a cylinder 1, an annular rod guide 2 fitted to the inner periphery of the end of the cylinder 1, a piston rod 3 inserted through the inner periphery of the rod guide 2 and movably inserted into the cylinder 1, a piston 4 connected to the piston rod 3 and inserted into the cylinder 1 to partition the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2 filled with a working fluid, and a seal member S that is annular, laminated on the side of the rod guide 2 opposite to the piston, fitted to the inner periphery of the end of the cylinder 1, and has the piston rod 3 inserted through its inner periphery. The seal member S includes an annular seal case 7 having an annular recess 7a on the inner periphery on the rod guide side, an annular base 8a, and an annular lip 8b that rises from the inner periphery of the base 8a toward the rod guide side and is in sliding contact with the outer periphery of the piston rod 3, and a seal ring 8 housed in the annular recess 7a. An annular seal holder 9 is laminated on the rod guide side of the base 8a of the seal ring 8, housed in the annular recess 7a, supports the outer periphery of the seal ring 8, and suppresses the diameter expansion of the lip 8b. A stopper 10 is attached to the seal case 7 and abuts against the side surface of the rod guide of the seal holder 9 to prevent the seal holder 9 and the seal ring 8 from falling off.

[0058] In the shock absorber D configured as described above, when assembling the shock absorber D, the stopper 10 in the seal member S maintains the seal ring 8 and the seal holder 9 in a state where they are assembled in the correct posture without falling off from the seal case 7. Therefore, according to the shock absorber D of the present embodiment, since the seal ring 8 and the seal holder 9 are maintained in a state where they are assembled in the correct posture with respect to the seal case 7, the seal ring 8 can be tightened with a uniform tightening force around the entire circumference of the piston rod 3, and stable sealing performance can be exhibited.

[0059] Furthermore, since the stopper 10 in the seal member S maintains the seal ring 8 and the seal holder 9 in a correctly assembled state without falling off from the seal case 7, after assembling the piston rod assembly, the seal member S can be separated from the rod guide 2 and the dust seal member 6, so that cutting chips and the like that can cause contaminants can be easily removed by blowing or vacuum. In addition, since the seal member S can hold the seal ring 8 and the seal holder 9 even when the rod guide 2 is not adjacent, only the dimensional accuracy with respect to the piston rod 3 is required and the dimensional accuracy with respect to the rod guide 2 is not required, so the machining accuracy requirements can be reduced and the machining cost can also be reduced.

[0060] Also, in the shock absorber D of the present embodiment, the seal case 7 has an annular socket 7b on the outer periphery on the rod guide side, the stopper 10 is annular and is fitted to the inner periphery of the socket 7b and abuts against the seal holder 9, and has a plate 10a having an inner diameter larger than the outer diameter of the piston rod 3, and a retaining ring (fixing member) 10b attached to the socket 7b for fixing the plate 10a to the seal case 7. In the shock absorber D configured in this way, the plate 10a can be fitted into the socket 7b to position the plate 10a in the radial direction, and the plate 10a can be fixed to the seal case 7 with the retaining ring (fixing member) 10b using the socket 7b. Therefore, according to the shock absorber D configured in this way, the plate 10a can be fixed to the seal case 7 at an appropriate position to prevent the seal ring 8 and the seal holder 9 from coming off. Further, during the extension operation of the shock absorber D in which the extension chamber R1 becomes high pressure, the pressure in the extension chamber R1 can be applied to the seal ring 8 to effectively prevent the working fluid from leaking from the cylinder 1.

[0061] Furthermore, in the shock absorber D of the present embodiment, the plate 10a includes an inner peripheral portion 10a1 that faces the seal holder 9 and forms an annular gap H2 therebetween, an outer peripheral portion 10a2 that is continuous with the outer periphery of the inner peripheral portion 10a1, abuts against the seal holder 9, and is fitted into the inner periphery of the socket 7b, one or more through holes 10a3 that penetrate the inner peripheral portion 10a1, and a chamfered portion 10a4 provided on the outer periphery of the outer peripheral portion 10a2 on the rod guide side. According to the shock absorber D configured in this way, since the gap H2 is formed between the plate 10a and the seal holder 9, interference between the plate 10a and the lip 8b of the seal ring 8 is avoided, and an excessive tightening force is not applied to the lip 8b, so that deterioration due to wear of the seal ring 8 can be suppressed. Also, according to the shock absorber D configured in this way, since the inner peripheral portion 10a1 of the plate 10a faces the seal holder 9 with the gap H2 therebetween, even if the seal holder 9 is deformed such that the lip 8b of the seal ring 8 expands in diameter and floats, the inner peripheral portion 10a1 of the plate 10a can support the seal holder 9, and the tightening force of the lip 8b can be maintained to exhibit good sealing performance. Further, since the plate 10a is provided with the through holes 10a3, the high pressure in the extension chamber R1 can be applied to the seal holder 9 when the shock absorber D extends and the pressure in the extension chamber R1 of the shock absorber D rises. Therefore, the shock absorber D can effectively prevent leakage of the working fluid from the cylinder 1 even during the extension operation.

[0062] Also, in the shock absorber D of the present embodiment, since the fixing member is the retaining ring 10b that is mounted on the inner periphery of the socket 7b, the plate 10a can be fixed to the seal case 7 without making the axial length of the socket 7b long. Therefore, according to the shock absorber D with the fixing member being the retaining ring 10b, it is possible to suppress an increase in the axial length of the seal member S and easily secure the stroke length. Further, since the plate 10a is provided with the chamfered portion 10a4, if an operator who mounts the plate 10a on the seal case 7 assembles it with the front and back of the plate 10a reversed, the outer periphery of the plate 10a faces the annular groove 7b1 of the socket 7b and the retaining ring 10b cannot be mounted on the socket 7b, making it impossible to fix the plate 10a. Therefore, it is possible to prevent incorrect assembly in which the plate 10a is assembled to the seal case 7 with the front and back reversed.

[0063] In addition, since the retaining ring 10b is attached to the socket 7b to fix the plate 10a, it is easy to fix the plate 10a to the seal case 7. However, as shown in FIG. 4, instead of the retaining ring 10b, the tip of the socket 7b may be clamped inward to fix the plate 10a in the state where the plate 10a is accommodated, thereby fixing the plate 10a to the seal case 7. In this case, the fixing member becomes the clamping portion 7d at the tip of the socket 7b. According to the shock absorber D configured in this way, the retaining ring 10b is not required, so the number of parts can be reduced. Further, as shown in FIG. 5, the plate 10a may be fixed to the seal case 7 by press-fitting the plate 10a into the inner circumference of the socket 7b. In this case, the fixing member is the socket 7b. According to the shock absorber D configured in this way, the retaining ring 10b is not required, so the number of parts can be reduced.

[0064] Note that the stopper may be configured as in the following modified examples. The stopper 20 of the first modified example is annular as shown in FIGS. 6 and 7, is fitted to the inner circumference of the socket 7b, abuts on the seal holder 9, and has an inner diameter larger than the outer diameter of the piston rod 3, and includes a plate 21 and a fixing member 22 that is attached to the socket 7b to fix the plate 21 to the seal case 7.

[0065] The plate 21 is annular and is fitted to the inner circumference of the socket 7b. The socket 7b in the seal case 7 is annular with an outer diameter smaller than the maximum outer diameter of the seal case 7, protrudes from the seal case 7 toward the piston side, and forms an annular gap with the cylinder 1.

[0066] The fixing member 22 is annular and includes a main body portion 22a that abuts against the rod guide side surface of the plate 21, and six arms 22b provided on the outer periphery of the main body portion 22a for gripping the outer periphery of the socket 7b. Further, the main body portion 22a has an inner diameter larger than the outer diameter of the piston rod 3, and is provided with six notches 22a1 formed to open from the inner periphery and extend toward the outer periphery. Note that the inner diameter of the plate 21 is equal to or larger than the diameter of the circumscribed circle C1 that contacts the tips of the notches 22a1 and is smaller than the outer diameter of the seal holder 9. When the plate 21 is fitted into the inner periphery of the socket 7b, it abuts against the rod guide side surface of the seal holder 9.

[0067] The arm 22b of the fixing member 22 has a bent tip portion and has a hook shape when viewed from the side of the fixing member 22. When it is fitted onto the outer periphery of the socket 7b, it tightly grips the outer periphery of the socket 7b. Therefore, by fitting the arm 22b onto the outer periphery of the socket 7b, the fixing member 22 can be fixed to the seal case 7. Note that the number of the installed arms 22b can be arbitrarily set as long as it is three or more. When the arms 22b are three or more and are provided at equal intervals on the outer periphery of the main body portion 22a, the fixing member 22 can be fixed to the socket 7b without eccentricity in the circumferential direction.

[0068] Then, when the fixing member 22 is attached to the seal case 7 as described above with the plate 21 fitted into the socket 7b of the seal case 7, the plate 21 is fixed to the seal case 7. Since the plate 21 abuts against the outer peripheral side of the rod guide side surface of the seal holder 9 and is fixed to the seal case 7, the seal ring 8 and the seal holder 9 in the annular recess 7a are prevented from falling out of the seal case 7.

[0069] Note that since the outer diameter of the socket 7b is smaller than the inner diameter of the cylinder 1, even if the arm 22b of the fixing member 22 grips the outer periphery of the socket 7b, the arm 22b does not interfere with the cylinder 1, and the seal member S1 can be easily inserted into the cylinder 1.

[0070] Further, in the buffer D of the present embodiment, the thickness, which is the axial length of the plate 21 of the stopper 20 in the first modification, is shorter than the axial length of the socket 7b, and the axial length of the tip of the arm 22b is also shorter than the axial length of the socket 7b. Therefore, when the fixing member 22 is attached to the socket 7b, the main body 22a of the fixing member 22 is in close contact with the rod guide side surface of the plate 21, and the plate 21 can be fixed to the seal case 7 without play.

[0071] In the seal member S1 configured as described above, since the outer periphery of the socket 7b is gripped by the arm 22b and the fixing member 22 is fixed to the seal case 7, if the pressing force of the arm 22b on the socket 7b is reduced, the seal member S1 can be easily assembled manually without using tools. Further, since the outer periphery of the socket 7b is gripped by the arm 22b and the fixing member 22 is fixed to the seal case 7, the plate 21 can be formed as a thin-walled annular ring, and the axial length of the seal member S1 can be shortened. In the case of the stopper 10 shown in FIGS. 2, 4, and 5, machining is required to provide a thin-walled inner peripheral portion 10a1 and a thick-walled outer peripheral portion 10a2 on the plate 10a, or to provide a chamfered portion 10a4 on the outer periphery, and it is necessary to chuck the outer periphery of the plate 10a. Therefore, the thickness of the plate 10a has to be increased to some extent. Thus, when the fixing member 22 includes an annular main body 22a that abuts against the rod guide side surface of the plate 21 and six arms 22b provided on the outer periphery of the main body 22a for gripping the outer periphery of the socket 7b as in the stopper 20 of the first modification, the thickness of the plate 21 can be reduced and the axial length of the seal member S1 can be shortened.

[0072] The seal member S1 configured as described above, like the seal member S, is pre-assembled and then incorporated into the piston rod assembly, inserted into the cylinder 1, and clamped between the caulking portion 1a and the C-ring 5 to be fixed to the cylinder 1. Even when assembling the piston rod assembly or inserting it into the cylinder 1, the stopper 20 prevents the seal ring 8 and the seal holder 9 from falling out of the annular recess 7a of the seal case 7, and maintains the seal ring 8 and the seal holder 9 in a state of being properly positioned and housed in the annular recess 7a.

[0073] Therefore, according to the shock absorber D provided with the seal member S1 configured as described above, since the seal ring 8 and the seal holder 9 are maintained in a state of being assembled to the seal case 7 in a correct posture, the seal ring 8 can be tightened with a uniform tightening force around the entire circumference of the piston rod 3, and stable sealing performance can be exhibited. Further, since the structure is adopted in which the outer circumference of the socket 7b is gripped by the arm 22b and the fixing member 22 is fixed to the seal case 7, the plate 21 can be made into a thin-walled annular ring, and the axial length of the seal member S1 can be shortened. Therefore, according to the shock absorber D provided with the seal member S1, it becomes easier to secure a longer stroke length.

[0074] Further, when the seal member S1 is fixed to the cylinder 1, since the socket 7b is housed in the concave portion 2d on the outer circumference of the rod guide 2, the main body portion 22a of the fixing member 22 abuts against the convex portion 2c of the rod guide 2 and is fixed to the cylinder 1 while being pressed together with the plate 21 by the axial force received from the caulking portion 1a with respect to the seal case 7. Since the inner peripheral portion of the main body portion 22a of the fixing member 22 supported by the convex portion 2c of the rod guide 2 faces the inner circumference of the seal holder 9, even if the seal holder 9 is deformed so as to float from the seal case 7 due to the expansion of the diameter of the lip 8b by the insertion of the piston rod 3 to the inner peripheral side, the seal holder 9 can be supported by the inner peripheral portion of the fixing member 22. In addition, since a gap is formed between the fixing member 22 and the seal holder 9 by the installation of the plate 21, interference between the fixing member 22 and the lip 8b of the seal ring 8 is avoided, and it is not necessary to apply an excessive tightening force to the lip 8b, and deterioration due to wear of the seal ring 8 can be suppressed.

[0075] In addition, the fixing member 22 of the stopper 20 has six notches 22a1 on its inner circumference, and the plate 21 has an inner diameter equal to or larger than the diameter of the circumscribed circle C1 where the tips of the notches 22a1 are in contact with each other and abuts against the seal holder 9. Therefore, even if the seal holder 9 is deformed so as to float from the seal case 7 and abuts against the inner circumference of the fixing member 22, the pressure in the extension chamber R1 can act on the seal holder 9 through the notches 22a1. Thus, when the shock absorber D extends, the high pressure in the extension chamber R1 that is compressed can act on the seal holder 9 to increase the tightening force that clamps the piston rod 3 by the lip 8b of the seal ring 8. Even if the seal holder 9 is deformed and abuts against the fixing member 22, since the inner diameter of the fixing member 22 is larger than the outer diameter of the piston rod 3, the pressure in the extension chamber R1 can act on the lip 8b of the seal ring 8. Note that the number of the notches 22a1 provided in the main body portion 22a of the fixing member 22 may be one or more and can be arbitrarily set.

[0076] Next, the stopper 30 of the second modified example will be described. As shown in FIGS. 8 and 9, the stopper 30 of the second modified example is annular and is fitted to the inner circumference of the socket 7b and abuts against the seal holder 9, and includes a plate 31 having an inner diameter larger than the outer diameter of the piston rod 3, and a fixing member 32 attached to the socket 7b to fix the plate 31 to the seal case 7.

[0077] The plate 31 is annular and is fitted to the inner circumference of the socket 7b. The socket 7b in the seal case 7 is annular, has an inner diameter that is enlarged in the middle, and has a stepped portion 7b2 on its inner circumference. In addition, the inner circumferential surface on the opening side from the stepped portion 7b2 is a tapered surface whose diameter increases toward the back side from the opening end, and the inner diameter of the stepped portion 7b2 is larger than the inner diameter of the opening end. Thus, since the inner circumference of the socket 7b on the opening end side rather than the stepped portion 7b2 is tapered, it has a portion with a diameter larger than the inner diameter of the opening end on its inner circumference.

[0078] The fixing member 32 has an annular main body 32a that abuts against the rod guide side surface of the plate 31, and three claws 32b provided on the outer periphery of the main body 32a that penetrate into the large-diameter portion that is the inner periphery of the socket 7b. Further, the main body 32a has an inner diameter larger than the outer diameter of the piston rod 3 and is provided with six notches 32a1 that open from the inner periphery and are formed toward the outer periphery. Note that the inner diameter of the plate 31 is equal to or larger than the diameter of the circumscribed circle C2 that contacts the tips of the notches 32a1 and is smaller than the outer diameter of the seal holder 9. When the plate 31 is fitted deeper than the stepped portion 7b2 on the inner periphery of the socket 7b, it abuts against the surface on the rod guide side of the seal holder 9.

[0079] Also, the outer diameter of the main body 32a is larger than the minimum diameter of the outer diameter of the plate 31 and the inner periphery of the socket 7b, and the fixing member 32 is accommodated on the opening side of the stepped portion 7b2 of the socket 7b. The claws 32b of the fixing member 32 protrude radially from the outer periphery of the main body 32a and have a shape with a tapered tip. Also, the diameter of the circumscribed circle C3 that contacts the tip of the claw 32b is larger than the inner diameter of the opening end of the socket 7b. Therefore, when the fixing member 32 is pushed into the socket 7b, the claws 32b are once bent and enter the socket 7b 、 Claw 32b is When returning to its original state by its own restoring force from the bent state, the claw 32b catches on the tapered inner peripheral surface of the socket 7b, and the fixing member 32 is fixed to the seal case 7. Note that the number of claws 32b can be arbitrarily set as long as it is two or more. When there are three or more claws 32b and they are provided at equal intervals on the outer periphery of the main body 32a, the fixing member 32 can be fixed to the socket 7b without play. Also, the large-diameter portion provided on the inner periphery of the socket 7b may be installed by providing an annular groove along the circumferential direction on the inner periphery.

[0080] Then, with the plate 31 fitted into the inner peripheral side of the socket 7b of the seal case 7 where the inner diameter of the socket 7b is small and deep, when the fixing member 32 is attached to the seal case 7 as described above, the plate 31 is fixed to the seal case 7. Since the plate 31 abuts against the outer peripheral side of the rod guide side surface of the seal holder 9 and is fixed to the seal case 7, the seal ring 8 and the seal holder 9 in the annular recess 7a are prevented from falling out of the seal case 7.

[0081] Further, if the thickness, which is the axial length of the plate 31 of the stopper 30 in the second modification of the shock absorber D of the present embodiment, is set to be equal to or greater than the height of the stepped portion 7b2 of the socket 7b, when the fixing member 32 is attached to the socket 7b, the main body portion 32a of the fixing member 32 abuts closely against the rod guide side surface of the plate 31, and the plate 31 can be firmly fixed to the seal case 7 without play.

[0082] In the seal member S2 configured in this way, on the inner periphery of the socket 7b, a tapered surface is formed on the inner peripheral surface on the opening end side with respect to the stepped portion 7b2, and a portion having a larger diameter than the inner diameter of the opening end is formed. The claw 32b is inserted into this portion, and the fixing member 32 is fixed to the seal case 7. Therefore, if the radial length of the claw 32b is made shorter, the seal member S2 can be easily assembled manually without using tools. Further, since the claw 32b is inserted into a portion having a larger diameter than the inner diameter of the opening end provided on the inner periphery of the socket 7b on the opening end side with respect to the stepped portion 7b2, and the fixing member 32 is fixed to the seal case 7, the plate 31 can be made into a thin-walled annular shape. Similar to the seal member S1, the axial length of the seal member S2 can be shortened.

[0083] The seal member S2 configured in this way, similar to the seal members S and S1, after being pre-assembled, is incorporated into the piston rod assembly, inserted into the cylinder 1, and clamped between the caulking portion 1a and the C-ring 5 to be fixed to the cylinder 1. Even when assembling the piston rod assembly or inserting it into the cylinder 1, the stopper 30 prevents the seal ring 8 and the seal holder 9 from falling out of the annular recess 7a of the seal case 7, and the seal ring 8 and the seal holder 9 are maintained in a state of being correctly positioned and housed in the annular recess 7a.

[0084] Therefore, according to the shock absorber D provided with the seal member S2 configured as described above, since the seal ring 8 and the seal holder 9 are maintained in a state of being assembled to the seal case 7 in the correct posture, the seal ring 8 can be tightened with a uniform tightening force around the entire circumference of the piston rod 3, and stable seal performance can be exhibited. Further, since a structure is adopted in which the claw 32b is inserted into a portion having a diameter larger than the inner diameter of the open end provided on the inner circumference of the socket 7b and on the open end side of the stepped portion 7b2, the plate 31 can be made into a thin-walled annular ring and the axial length of the seal member S2 can be shortened. Therefore, according to the shock absorber D provided with the seal member S2, it becomes easier to secure a longer stroke length.

[0085] Further, when the seal member S2 is fixed to the cylinder 1, since the socket 7b is accommodated in the concave portion 2d on the outer circumference of the rod guide 2, the main body portion 32a of the fixing member 32 abuts against the convex portion 2c of the rod guide 2 and is fixed to the cylinder 1 while being pressed together with the plate 31 by the axial force received from the caulking portion 1a with respect to the seal case 7. Since the inner peripheral portion of the main body portion 32a of the fixing member 32 supported by the convex portion 2c of the rod guide 2 faces the inner circumference of the seal holder 9, even if the seal holder 9 is deformed so as to float from the seal case 7 due to the expansion of the diameter of the lip 8b by the insertion of the piston rod 3 to the inner peripheral side, the seal holder 9 can be supported by the inner peripheral portion of the fixing member 32. In addition, since a gap is formed between the fixing member 32 and the seal holder 9 by the installation of the plate 31, interference between the fixing member 32 and the lip 8b of the seal ring 8 is avoided, and it is not necessary to apply an excessive tightening force to the lip 8b, and deterioration due to wear of the seal ring 8 can be suppressed.

[0086] Further, the fixing member 32 of the stopper 30 has six notches 32a1 on its inner periphery, and the plate 31 has an inner diameter equal to or larger than the diameter of the circumscribed circle C2 in contact with the tips of the notches 32a1 and abuts against the seal holder 9. Therefore, even if the seal holder 9 is deformed to float from the seal case 7 and abuts against the inner periphery of the fixing member 32, the pressure in the extension chamber R1 can act on the seal holder 9 through the notches 32a1. Thus, when the shock absorber D extends, the high pressure in the extension chamber R1 compressed at that time can act on the seal holder 9 to increase the tightening force for clamping the piston rod 3 by the lip 8b of the seal ring 8. Even if the seal holder 9 is deformed and abuts against the fixing member 32, the inner diameter of the fixing member 32 is larger than the outer diameter of the piston rod 3, so the pressure in the extension chamber R1 can act on the lip 8b of the seal ring 8. The number of the notches 32a1 provided in the main body portion 32a of the fixing member 32 may be one or more and can be arbitrarily set.

[0087] Next, the stopper 40 of the third modification will be described. As shown in FIGS. 10 and 11, the stopper 40 of the third modification includes a plate 41 that is annular, fitted to the inner periphery of the socket 7b, abuts against the seal holder 9, and has an inner diameter larger than the outer diameter of the piston rod 3, and a fixing member 42 that is attached to the socket 7b and fixes the plate 41 to the seal case 7.

[0088] The plate 41 is annular and fitted to the inner periphery of the socket 7b. The socket 7b in the seal case 7 is annular, has an inner diameter that is enlarged in the middle, has a stepped portion 7b2 on its inner periphery, and further includes an annular groove 7b3 formed along the circumferential direction on the inner periphery on the opening side from the stepped portion 7b2 and three vertical grooves 7b4 formed along the axial direction from the opening end and communicating with the annular groove 7b3.

[0089] The fixing member 42 is annular and has a main body portion 42a that abuts against the rod guide side surface of the plate 41, and three protrusions 42b that are provided at positions corresponding to the longitudinal groove 7b4 on the outer periphery of the main body portion 42a, can be inserted into the longitudinal groove 7b4 of the socket 7b, and are fitted into the annular groove 7b3. The main body portion 42a has an inner diameter larger than the outer diameter of the piston rod 3 and is provided with six notches 42a1 that open from the inner periphery and are formed toward the outer periphery. Note that the inner diameter of the plate 41 is equal to or larger than the diameter of the circumcircle C4 that contacts the tips of the notches 42a1 and is smaller than the outer diameter of the seal holder 9. When the plate 41 is fitted into the inner periphery on the back side of the stepped portion 7b2 of the socket 7b, it abuts against the surface on the rod guide side of the seal holder 9.

[0090] Further, the outer diameter of the main body portion 42a is larger than the minimum diameter of the outer diameter of the plate 41 and the inner circumference of the socket 7b, and the fixing member 42 is accommodated on the opening side of the stepped portion 7b2 of the socket 7b. The protrusions 42b of the fixing member 42 are shaped to correspond to the longitudinal groove 7b4 formed on the inner circumference of the socket 7b when viewed from the axial direction, and protrude radially from the position corresponding to the longitudinal groove 7b4 on the outer periphery of the main body portion 42a. Note that the same number of protrusions 42b as the longitudinal groove 7b4 are provided on the outer periphery of the main body portion 42a, but the number of installed protrusions 42b may be less than or equal to the number of installed longitudinal grooves 7b4 as long as all the protrusions 42b of the fixing member 42 can be inserted into the longitudinal grooves 7b4 provided in the socket 7b. Also, the diameter of the circumcircle C5 that contacts the tips of the protrusions 42b is larger than the inner diameter of the inner circumference of the socket 7b on the opening end side of the stepped portion 7b2 and is equal to or smaller than the inner diameter of the annular groove 7b3.

[0091] Therefore, first, the plate 41 is fitted to the inner circumference on the back side of the stepped portion 7b2 of the socket 7b. Then, with each projection 42b of the fixing member 42 facing the longitudinal groove 7b4 of the socket 7b in the axial direction of the seal case 7 and the fixing member 42, when the fixing member 42 is inserted into the socket 7b, the projection 42b is inserted into the longitudinal groove 7b4 and the fixing member 42 abuts against the plate 41. In this state, since the projection 42b enters the annular groove 7b3, if the fixing member 42 is rotated in the circumferential direction, the projection 42b moves in the circumferential direction within the annular groove 7b3 and no longer faces the longitudinal groove 7b4, and the fixing member 42 is fixed to the socket 7b. Since the plate 41 abuts against the outer peripheral side of the rod guide side surface of the seal holder 9 and is fixed to the seal case 7, the seal ring 8 and the seal holder 9 within the annular recess 7a are prevented from falling off from the seal case 7.

[0092] Also, if the thickness, which is the axial length of the plate 41 of the stopper 40 in the third modification of the shock absorber D of the present embodiment, is set to be equal to or greater than the height of the stepped portion 7b2 of the socket 7b, when the fixing member 42 is attached to the socket 7b, the main body portion 42a of the fixing member 42 closely adheres to the rod guide side surface of the plate 41 and the plate 41 can be firmly fixed to the seal case 7 without looseness.

[0093] In the seal member S3 configured in this way, since the projection 42b is inserted into the annular groove 7b3 provided on the inner circumference of the socket 7b on the opening side rather than the stepped portion 7b2, the fixing member 42 is fixed to the seal case 7, so the seal member S3 can be easily assembled manually without using tools. Also, since the projection 42b is inserted into the annular groove 7b3 provided on the inner circumference of the socket 7b on the opening side rather than the stepped portion 7b2, the fixing member 42 is fixed to the seal case 7, the plate 41 can be made into a thin-walled ring, and similar to the seal member S1, the axial length of the seal member S3 can be shortened. Note that since the annular groove 7b3 is formed at a position separated from the deepest part of the socket 7b toward the opening side, the annular groove 7b3 can be processed without difficulty.

[0094] The seal member S3 configured in this way, like the seal members S, S1, and S2, after being pre-assembled, is incorporated into the piston rod assembly, inserted into the cylinder 1, and clamped between the caulking portion 1a and the C-ring 5 and fixed to the cylinder 1. Even if vibration acts on the seal member S3 during the conveyance of the piston rod assembly, the stopper 40 prevents the seal ring 8 and the seal holder 9 from falling out of the annular recess 7a of the seal case 7, and the seal ring 8 and the seal holder 9 are maintained in a state of being stored in the annular recess 7a in the correct posture.

[0095] Therefore, according to the shock absorber D provided with the seal member S3 configured in this way, since the seal ring 8 and the seal holder 9 are maintained in a state of being assembled to the seal case 7 in the correct posture, the seal ring 8 can be tightened with a uniform tightening force around the entire circumference of the piston rod 3, and stable seal performance can be exhibited. Further, an annular groove 7b3 provided on the inner circumference of the socket 7b on the opening side rather than the stepped portion 7b2 and a vertical groove 7b4 communicating with the annular groove 7b3 are provided, and the protrusion 42b is fitted into the annular groove 7b3 and the fixing member 42 is fixed to the seal case 7. Since the plate 31 can be made into a thin-walled ring and the axial length of the seal member S3 can be shortened, according to the shock absorber D provided with the seal member S3, it becomes easier to secure a longer stroke.

[0096] Further, when the seal member S3 is fixed to the cylinder 1, since the socket 7b is accommodated in the recess 2d on the outer circumference of the rod guide 2, the main body portion 42a of the fixing member 42 abuts against the convex portion 2c of the rod guide 2 and is fixed to the cylinder 1 while being pressed together with the plate 41 by the axial force received from the caulking portion 1a with respect to the seal case 7. Since the inner peripheral portion of the main body portion 42a of the fixing member 42 supported by the convex portion 2c of the rod guide 2 faces the inner circumference of the seal holder 9, even if the seal holder 9 is deformed so as to float from the seal case 7 due to the diameter expansion of the lip 8b by the insertion of the piston rod 3 to the inner peripheral side, the seal holder 9 can be supported by the inner peripheral portion of the fixing member 42.

[0097] Further, the fixing member 42 of the stopper 40 has six notches 42a1 on its inner periphery, and since the plate 41 has an inner diameter equal to or greater than the diameter of the circumscribed circle C4 that contacts the tips of the notches 42a1 and abuts against the seal holder 9, even if the seal holder 9 is deformed to lift from the seal case 7 and abut against the inner periphery of the fixing member 42, the pressure in the extension chamber R1 can act on the seal holder 9 through the notches 42a1. Therefore, when the shock absorber D extends, the high pressure in the extension chamber R1 that is compressed can act on the seal holder 9 to increase the clamping force that tightens the piston rod 3 of the lip 8b in the seal ring 8. Note that even if the seal holder 9 is deformed and abuts against the fixing member 42, the inner diameter of the fixing member 42 is larger than the outer diameter of the piston rod 3, so the pressure in the extension chamber R1 can act on the lip 8b of the seal ring 8. Note that the number of notches 42a1 provided in the main body portion 42a of the fixing member 42 may be one or more and can be arbitrarily set.

[0098] Note that in the second and third modified examples, the socket 7b of the seal case 7 has a stepped portion 7b2, and the outer diameters of the plates 31 and 41 are made smaller than the main body portions 32a and 42a of the fixing members 32 and 42, but it does not necessarily have to have the stepped portion 7b2.

[0099] Further, the stopper may be configured as in the following modified examples. The stopper 50 of the fourth modified example is annular as shown in FIG. 12, abuts against the rod guide side surface of the seal holder 9 and the seal case 7, and has a plate 51 with an inner diameter larger than the outer diameter of the piston rod 3, and a fixing member 52 that grips the outer periphery of the seal case 7 and fixes the plate 51 to the seal case 7.

[0100] As shown in FIG. 12, the seal case 7 has a shape in which the socket 7b in the seal case 7 shown in FIG. 6 is abolished, is annular, and has an annular recess 7a provided on the inner periphery of the side end of the rod guide 2 at the lower end in FIG. 12, an outer diameter small diameter portion 7d provided by forming the outer periphery of the lower end in FIG. 12, which becomes the rod guide side end, to be small diameter, and an annular recess 7c provided on the outer periphery of the upper end in FIG. 12, which becomes the anti-rod guide side and the upper end in FIG. 12.

[0101] The plate 51 is annular, having an inner diameter smaller than the outer diameter of the seal holder 9 and an outer diameter larger than the outer diameter of the seal holder 9 and smaller than the outer diameter of the rod guide side end of the seal case 7.

[0102] The fixing member 52 has substantially the same configuration as the fixing member 22 of the first modification shown in FIG. 6, and includes an annular main body portion 52a facing the rod guide side surface of the plate 51, and an outer periphery of the main body portion 52a provided on the outside of the seal case 7 diameter and six arms 52b that grip the outer periphery of the small-diameter portion 7d. The main body portion 52a has an inner diameter larger than the outer diameter of the piston rod 3 and is provided with six notches 52a1 formed to open from the inner periphery and face the outer periphery. The arm 52b of the fixing member 52 has a bent tip and has a hook claw shape when viewed from the side, and when fitted to the outer periphery of the small-diameter outer diameter portion 7d, it compresses the outer periphery of the small-diameter outer diameter portion 7d to grip the seal case 7.

[0103] The inner diameter of the plate 51 is equal to or larger than the diameter of the circumscribed circle in contact with the tips of the notches 52a1 and smaller than the outer diameter of the seal holder 9, and the outer diameter of the plate 51 is set to fit into the inner surface of the arm 52b of the fixing member 52. Further, the stopper 50 of the present embodiment includes a washer 53 interposed between the plate 51 and the fixing member 52. The washer 53 has an inner diameter substantially the same as the inner diameter of the plate 51. Note that the outside diameter of the washer is smaller than the outer diameter of the plate 51 Furthermore, the vertical length in FIG. 12 from the tip of the arm 52b to the main body portion 52a is longer than the axial length when the plate 51 and the washer 53 are laminated.

[0104] Therefore, when the plate 51 is stacked on the base 9a of the seal holder 9 and the seal case 7, and the washer 53 is stacked on the rod guide side of the plate 51, and then the outer periphery of the small-diameter outer diameter portion 7d is gripped by the arm 52b and the fixing member 52 is attached to the seal case 7, the seal ring 8, the seal holder 9, the plate 51, and the washer 53 are clamped and fixed between the fixing member 52 and the seal case 7.

[0105] Further, since the plate 51 fits into the inner surface of the arm 52b of the fixing member 52, the plate 51 is centered by the fixing member 52 and fixed to the seal case 7. Since the outer diameter of the washer 53 is set to a diameter such that it does not contact the inner surface of the arm 52b, the curved portion at the boundary between the arm 52b and the main body portion 52a is avoided, so that the main body portion 52a of the fixing member 52 contacts the washer 53 without floating, and the seal ring 8, the seal holder 9, the plate 51, and the washer 53 can be firmly fixed to the seal case 7. The washer 53 is interposed when the seal member S4 is fixed to the cylinder 1 so that the main body portion 52a of the fixing member 52 contacts the convex portion 2c of the rod guide 2 and receives the axial force received from the caulking portion 1a with respect to the seal case 7. However, it can be omitted when the plate 51 and the fixing member 52 can sufficiently receive the axial force.

[0106] Then, when the fixing member 52 is attached to the seal case 7 with the plate 51 stacked on the seal case 7 as described above, the plate 51 is fixed to the seal case 7. Since the plate 51 contacts the outer peripheral side of the rod guide side surface of the seal holder 9 and is fixed to the seal case 7, the seal ring 8 and the seal holder 9 in the annular recess 7a are prevented from falling off from the seal case 7.

[0107] Also, in the stopper 50 in the fourth modification of the shock absorber D of the present embodiment, it is not necessary to provide the socket 7b in the seal case 7, and since the fixing member 52 is fixed to the seal case 7 by gripping the outer periphery of the seal case 7, the plate 51 can be clamped between the fixing member 52 and the seal case 7, and the plate 51 is in close contact with the rod guide side surface of the seal case 7 and is fixed to the seal case 7 without looseness.

[0108] In the seal member S4 configured in this manner, since the fixing member 52 is fixed to the seal case 7 by gripping the outer periphery of the seal case 7, if the pressing force of the arm 52b is reduced, the seal member S4 can be easily assembled manually without using tools. Further, since the fixing member 52 is fixed to the seal case 7 by gripping the outer periphery of the seal case 7, the plate 51 can be formed as a thin-walled annular ring, and the axial length of the seal member S4 can be shortened.

[0109] The seal member S4 configured in this manner, like the seal member S, is pre-assembled and then incorporated into the piston rod assembly, inserted into the cylinder 1, and fixed to the cylinder 1 by being sandwiched between the caulking portion 1a and the C-ring 5. Even when assembling the piston rod assembly or inserting it into the cylinder 1, the stopper 50 prevents the seal ring 8 and the seal holder 9 from falling out of the annular recess 7a of the seal case 7, and the seal ring 8 and the seal holder 9 are maintained in a state of being received in the annular recess 7a in the correct posture.

[0110] Therefore, according to the shock absorber D provided with the seal member S4 configured in this manner, since the seal ring 8 and the seal holder 9 are maintained in a state of being assembled to the seal case 7 in the correct posture, the seal ring 8 can be tightened with a uniform pressing force around the entire circumference of the piston rod 3, and stable seal performance can be exhibited. Further, since a structure is adopted in which the fixing member 52 is fixed to the seal case 7 by gripping the outer periphery of the seal case 7, the plate 51 can be formed as a thin-walled annular ring and the axial length of the seal member S4 can be shortened. Therefore, according to the shock absorber D provided with the seal member S4, it becomes easier to secure a longer stroke.

[0111] Also, when the seal member S4 is fixed to the cylinder 1, the main body portion 52a of the fixing member 52 abuts against the convex portion 2c of the rod guide 2 and is fixed to the cylinder 1 while being pressed together with the plate 51 by the axial force received from the caulking portion 1a with respect to the seal case 7. Since the inner peripheral portion of the main body portion 52a of the fixing member 52 supported by the convex portion 2c of the rod guide 2 faces the inner periphery of the seal holder 9, even if the seal holder 9 is deformed to float from the seal case 7 due to the diameter expansion of the lip 8b by the insertion of the piston rod 3 to the inner peripheral side, the seal holder 9 can be supported by the inner peripheral portion of the fixing member 52. In addition, since a gap is formed between the fixing member 52 and the seal holder 9 by the installation of the plate 51, interference between the fixing member 52 and the lip 8b of the seal ring 8 is avoided, and an excessive pressing force is not applied to the lip 8b, so that deterioration due to wear of the seal ring 8 can be suppressed.

[0112] Further, the fixing member 52 of the stopper 50 has six notches 52a1 on the inner periphery, and the plate 51 has an inner diameter equal to or larger than the diameter of the circumscribed circle in contact with the tips of the notches 52a1 and abuts against the seal holder 9. Therefore, even if the seal holder 9 is deformed to float from the seal case 7 and abuts against the inner periphery of the fixing member 52, the pressure in the extension chamber R1 can act on the seal holder 9 through the notches 52a1. Thus, when the shock absorber D extends, the high pressure in the extension chamber R1 compressed at that time can act on the seal holder 9 to increase the pressing force for clamping the piston rod 3 of the lip 8b in the seal ring 8. Even if the seal holder 9 is deformed and abuts against the fixing member 52, since the inner diameter of the fixing member 52 is larger than the outer diameter of the piston rod 3, the pressure in the extension chamber R1 can act on the lip 8b of the seal ring 8. The number of the notches 52a1 provided in the main body portion 52a of the fixing member 52 may be one or more and can be arbitrarily set.

[0113] As described above, the preferred embodiments of the present invention have been described in detail, but modifications, deformations, and changes are possible without departing from the scope of the claims.

Description of Reference Numerals

[0114] 1 ··· cylinder, 2 ··· rod guide, 3 ··· piston rod, 4 ··· piston, 7 ··· seal case, 7a ··· annular recess, 7b ··· socket, 7b3 ··· annular groove, 7b4 ··· longitudinal groove, 8 ··· seal ring, 8a ··· base, 8b ··· lip, 9 ··· seal holder, 10, 20, 30, 40 ,50 ··· stopper, 10a, 21, 31, 41 ,51 ··· plate, 10a1 ··· inner peripheral portion, 10a2 ··· outer peripheral portion, 10a3 ··· through hole, 10a4 ··· chamfered portion, 10b ··· retaining ring (fixing member), 22, 32, 42 ,52 ··· fixing member, 22a, 32a, 42a ,52a ···· body portion, 22a1, 32a1, 42a1 ,52a1 ··· notch, 22b ,52b ··· arm, 32b ··· claw, 42b ··· protrusion, C1, C2, C4 ··· circumscribed circle, D ··· buffer, R1 ··· extension side chamber, R2 ··· compression side chamber, S, S1, S2, S3 ··· seal member

Claims

1. A cylinder, an annular rod guide fitted to the inner circumference of the end of the cylinder, a piston rod inserted through the inner circumference of the rod guide and movably inserted into the cylinder, a piston connected to the piston rod and inserted into the cylinder, partitioning the inside of the cylinder into an extension chamber and a compression chamber filled with a working fluid, a seal member that is independent of the rod guide and is annular, laminated on the side of the rod guide opposite to the piston, fitted to the inner circumference of the end of the cylinder, and having the piston rod inserted through its inner circumference, The seal member includes an annular seal case having an annular recess on the inner circumference on the rod guide side, a seal ring having an annular base and an annular lip rising from the inner circumference of the base toward the rod guide side and slidingly contacting the outer circumference of the piston rod, and being accommodated in the annular recess, an annular seal holder laminated on the rod guide side of the base of the seal ring and accommodated in the annular recess, supporting the outer circumference of the lip and suppressing the diameter expansion of the lip, and a stopper that is sandwiched between the rod guide and the seal case, is attached to the seal case, and contacts the side surface of the seal holder on the rod guide side to prevent the seal holder and the seal ring from falling off. A shock absorber characterized by the above.

2. A cylinder, an annular rod guide fitted to the inner circumference of the end of the cylinder, a piston rod inserted through the inner circumference of the rod guide and movably inserted into the cylinder, a piston connected to the piston rod and inserted into the cylinder, partitioning the inside of the cylinder into an extension chamber and a compression chamber filled with a working fluid, an annular seal member laminated on the side of the rod guide opposite to the piston, fitted to the inner circumference of the end of the cylinder, and having the piston rod inserted through its inner circumference, The seal member includes an annular seal case having an annular recess on the inner circumference on the rod guide side and an annular socket on the outer circumference on the rod guide side, a seal ring having an annular base and an annular lip rising from the inner circumference of the base toward the rod guide side and slidingly contacting the outer circumference of the piston rod, and being accommodated in the annular recess, An annular seal holder that is laminated on the rod guide side of the base of the seal ring, is housed in the annular recess, supports the outer periphery of the lip, and suppresses the diameter expansion of the lip. It has a stopper that is attached to the seal case, abuts against the rod guide side surface of the seal holder, and prevents the seal holder and the seal ring from falling off. The stopper includes an annular plate that is fitted to the inner periphery of the socket, abuts against the seal holder, and has an inner diameter larger than the outer diameter of the piston rod, and a fixing member that is attached to the socket and fixes the plate to the seal case. The fixing member has a main body portion that is annular and abuts against the rod guide side surface of the plate, and three or more arms provided on the outer periphery of the main body portion that grip the outer periphery of the socket. The main body portion has an inner diameter larger than the outer diameter of the piston rod and has one or more notches formed so as to open from the inner periphery toward the outer periphery. The plate has an inner diameter equal to or larger than the diameter of the circumscribed circle that contacts the tips of the notches. A shock absorber characterized by the above.

3. A cylinder, an annular rod guide fitted to the inner periphery of the end of the cylinder, a piston rod inserted through the inner periphery of the rod guide and movably inserted into the cylinder, a piston connected to the piston rod and inserted into the cylinder, partitioning the inside of the cylinder into an extension chamber and a compression chamber filled with a working fluid, and an annular seal member that is laminated on the side of the rod guide opposite to the piston of the rod guide, is fitted to the inner periphery of the end of the cylinder, and has the piston rod inserted through its inner periphery. The seal member has an annular seal case having an annular recess on the inner periphery on the rod guide side and an annular socket on the outer periphery on the rod guide side, and a seal ring having an annular base and an annular lip rising from the inner periphery of the base toward the rod guide side and slidably contacting the outer periphery of the piston rod, and is housed in the annular recess. An annular seal holder that is laminated on the rod guide side of the base of the seal ring, is housed in the annular recess, supports the outer periphery of the lip, and suppresses the diameter expansion of the lip. It has a stopper that is attached to the seal case, abuts against the rod guide side surface of the seal holder, and prevents the seal holder and the seal ring from falling off. The stopper includes an annular plate that is fitted to the inner circumference of the socket, abuts against the seal holder, and has an inner diameter larger than the outer diameter of the piston rod, and a fixing member that is attached to the socket and fixes the plate to the seal case. The socket has a portion on its inner circumference that is larger in diameter than the inner diameter at the open end. The fixing member has a main body portion that is annular and abuts against the rod guide side surface of the plate, and a plurality of claws provided on the outer circumference of the main body portion that penetrate into the larger-diameter portion of the socket. The main body portion has an inner diameter larger than the outer diameter of the piston rod and has one or more notches formed so as to open from the inner circumference toward the outer circumference. The plate has an inner diameter equal to or larger than the diameter of the circumscribed circle that contacts the tips of the notches. A shock absorber characterized by the above.

4. A cylinder, an annular rod guide fitted to the inner circumference of the end of the cylinder, a piston rod inserted through the inner circumference of the rod guide and movably inserted into the cylinder, a piston connected to the piston rod and inserted into the cylinder, which divides the inside of the cylinder into an extension chamber and a compression chamber filled with a working fluid, an annular seal member that is laminated on the side of the rod guide opposite to the piston, fitted to the inner circumference of the end of the cylinder, and has the piston rod inserted through its inner circumference, The seal member includes an annular seal case having an annular recess on the inner circumference on the rod guide side and an annular socket on the outer circumference on the rod guide side, a seal ring having an annular base portion and an annular lip rising from the inner circumference of the base portion toward the rod guide side and slidingly contacting the outer circumference of the piston rod, and being housed in the annular recess, an annular seal holder laminated on the rod guide side of the base portion of the seal ring, housed in the annular recess, and supporting the outer circumference of the lip to suppress the expansion of the lip, and a stopper attached to the seal case, abutting against the rod guide side surface of the seal holder, and preventing the seal holder and the seal ring from falling off. The stopper includes an annular plate that is fitted to the inner circumference of the socket, abuts against the seal holder, and has an inner diameter larger than the outer diameter of the piston rod, and a fixing member that is attached to the socket and fixes the plate to the seal case. The socket includes an annular groove provided on the inner circumference and at least one or more longitudinal grooves formed axially along the opening end on the inner circumference and communicating with the annular groove. The fixing member has a main body portion that is annular and abuts against the rod guide side surface of the plate, and one or more protrusions provided at positions corresponding to the longitudinal grooves on the outer circumference of the main body portion, which can be inserted into the longitudinal grooves of the socket and fitted into the annular groove. The main body portion has a plurality of notches formed with an inner diameter larger than the outer diameter of the piston rod and opening from the inner circumference toward the outer circumference. The plate has an inner diameter equal to or larger than the diameter of the circumscribed circle that contacts the tips of the notches. A shock absorber characterized by the above.

5. A cylinder, an annular rod guide fitted to the inner circumference of the end of the cylinder, a piston rod inserted through the inner circumference of the rod guide and movably inserted into the cylinder, a piston connected to the piston rod and inserted into the cylinder, partitioning the inside of the cylinder into an extension chamber and a compression chamber filled with a working fluid, and an annular seal member laminated on the side of the rod guide opposite to the piston, fitted to the inner circumference of the end of the cylinder, and having the piston rod inserted through the inner circumference. The seal member has an annular seal case having an annular recess on the inner circumference on the rod guide side, a seal ring having an annular base portion and an annular lip rising from the inner circumference of the base portion toward the rod guide side and slidingly contacting the outer circumference of the piston rod, and being accommodated in the annular recess, an annular seal holder laminated on the rod guide side of the base portion of the seal ring and accommodated in the annular recess, supporting the outer circumference of the lip and suppressing the diameter expansion of the lip, and a stopper attached to the seal case and abutting against the rod guide side surface of the seal holder to prevent the seal holder and the seal ring from falling off. The stopper has an annular plate that abuts against the rod guide side surface of the seal holder and the seal case and has an inner diameter larger than the outer diameter of the piston rod, and a fixing member that grips the outer circumference of the seal case and fixes the plate to the seal case. A shock absorber characterized by the above.

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