Cylinder device and sealing element

Abstract

Cylinder device (10) comprising: a cylinder (11) in which a working fluid is enclosed; a rod (22) projecting from at least one end of the cylinder (11); a rod guide (25) formed on one end side of the cylinder (11); an annular closure area (88) which is formed further out in an in / out direction of the cylinder (11) than the rod guide (25) such that it closes one end side of the cylinder (11); and an annular sealing ring (89) which is arranged inwards in the in / out direction of the cylinder (11) from an outer circumferential side of the closure area (88) such that it comes into contact with an outer circumferential section of the rod guide (25) and an inner circumferential section of the cylinder (11), wherein the sealing ring (89) has: a front-end outer circumferential sealing area (101, 102) which is designed on an outer circumferential side such thatthat it comes into contact with the inner circumferential section of the cylinder (11); a base-end outer circumferential sealing area (102, 103) which is formed closer to the closure area (88) on the outer circumferential side than the front-end outer circumferential sealing area (101, 102) such that it comes into contact with the inner circumferential section of the cylinder (11); a front-end inner circumferential contact area (104, 105) which is formed on the inner circumferential side such that it comes into contact with the outer circumferential section of the rod guide (25); and a base-end inner circumferential contact area (105, 106) which is formed closer to the closure area (88) on the inner circumferential side than the front-end inner circumferential contact area (104, 105) such that it comes into contact with the outer circumferential section of the rod guide (25), wherein the front-end inner circumferential contact area (104, 105) and the base-end inner circumferential contact area (105,106) is formed by convex areas projecting in a radial direction, the convex areas being a front-end inner circumferential convex area (117, 118) formed on the front-end inner circumferential contact area (104, 105), and a base-end inner circumferential convex area (118, 119) formed on the base-end inner circumferential contact area (105, 106), and the convex areas coming into contact with the outer circumferential section of the rod guide (25) such that the front-end outer circumferential sealing area (101, 102) and the base-end outer circumferential sealing area (102, 103) are pressed outwards in the radial direction.

Description

Field of the InventionThe present invention relates to a cylinder device and a sealing member. Priority is claimed on Japanese Patent Application No. 2013-205281 filed on Sep. 30, 2013, the contents of which are incorporated herein by reference.Prior ArtA technology is known in which an inner peripheral portion of a cylinder of a cylinder device is sealed using a seal ring (see, for example, JP 2011-52732 A).Further cylinder devices are known from WO 2007 / 066 504 A1 and JP H03-51246 U.SUMMARY OF THE INVENTIONTechnical ProblemIn order to increase the sealing effect of a sealing ring, it is considered to increase the volume of the sealing ring. However, when the volume of the seal ring is increased, the mounting of the seal ring to a cylinder device is made difficult.The present invention provides a cylinder device and a sealing member capable of improving the mounting properties of a sealing ring.Solution of the ProblemAccording to a first aspect of the present invention, a cylinder device includes: a cylinder in which a working fluid is sealed; a rod protruding from at least one end of the cylinder; an annular member formed on an inner side of the cylinder; an annular closing portion formed more outward in a cylinder on / off direction than the annular member so as to close the one end side of the cylinder; and an annular sealing ring disposed inwardly in the cylinder on / off direction from an outer circumferential side of the closing portion so as to come into contact with an outer circumferential portion of the annular member and an inner circumferential portion of the cylinder.The seal ring includes: a front end side outer peripheral sealing portion formed on an outer peripheral side so as to come into contact with the inner peripheral portion of the cylinder; a base end side outer peripheral sealing portion formed on the outer peripheral side closer to the sealing portion than the front end side outer peripheral sealing portion so as to come into contact with the inner peripheral portion of the cylinder; a front end side inner peripheral abutting portion formed on the inner peripheral side so as to come into contact with the outer peripheral portion of the annular member; and a base end side inner peripheral abutting portion formed on the inner peripheral side closer to the sealing portion than the front end side inner peripheral abutting portion so as to come into contact with the outer peripheral portion of the annular member.At least one set of sealing portions or abutting portions of the front end side outer peripheral sealing portion and the base end side outer peripheral sealing portion, and the front end side inner peripheral abutting portion and the base end side inner peripheral abutting portion are formed by convex portions protruding in a radial direction.According to a second aspect of the present invention, the convex portions are a front end side inner peripheral convex portion formed on the front end side inner peripheral abutting portion and a base end side inner peripheral convex portion formed on the base end side inner peripheral abutting portion.The convex portions come into contact with the outer peripheral portion of the annular member such that the front-end-side outer peripheral sealing portion and the base-end-side outer peripheral sealing portion are pushed outward in the radial direction.According to a third aspect of the present invention, the shape of the seal ring is formed such that, when the seal ring is interposed between the outer peripheral portion of the annular member and the inner peripheral portion of the cylinder, the base-end-side inner peripheral convex portion comes into contact with the annular member before the front-end-side inner peripheral convex portion comes into contact with the annular member.According to a fourth aspect of the invention, the shape of the seal ring is formed such that when the seal ring is inserted between the outer peripheral portion of the annular member and the inner peripheral portion of the cylinder, the base-end-side inner peripheral convex portion comes into contact with the annular member and the base-end-side outer peripheral convex portion comes into contact with the inner peripheral portion of the cylinder before a state is reached in which the front-end-side inner peripheral convex portion comes into contact with the annular member and the front-end-side outer peripheral sealing portion comes into contact with the inner peripheral portion of the cylinder.According to a fifth aspect of the present invention, the convex portions are: a front end side outer peripheral convex portion formed on the front end side outer peripheral sealing portion; and a base end side outer peripheral convex portion formed on the base end side outer peripheral sealing portion. The convex portions come into contact with the inner peripheral portion of the cylinder such that the front end side inner peripheral abutting portion and the base end side inner peripheral abutting portion are pushed inward in the radial direction.According to a sixth aspect of the present invention, the sealing ring is formed integrally with the closure region.According to a seventh aspect of the present invention, an outer diameter of the seal ring is larger than an inner diameter of the inner peripheral portion of the cylinder.According to an eighth aspect of the present invention, a contact surface of the annular member with the seal ring may be an inclined surface.According to a ninth aspect of the present invention, the front end side outer peripheral sealing portion and the front end side inner peripheral abutting portion, and the base end side outer peripheral sealing portion and the base end side inner peripheral abutting portion may overlap each other at positions in an axial direction.According to a tenth aspect of the present invention, a seal member having an annular inner peripheral portion and an annular member formed in an inner peripheral portion comes into contact to seal the inner peripheral portion.The seal member includes an annular seal portion that is coaxially disposed with the annular member, and an annular seal ring that is integrally formed with an outer circumferential side of the seal portion so as to come into contact with the inner circumferential portion.The seal ring includes: a front end side outer peripheral sealing portion formed on the outer peripheral side so as to come into contact with the inner peripheral portion; a base end side outer peripheral sealing portion formed on the outer peripheral side closer to the closing portion than the front end side outer peripheral sealing portion so as to come into contact with the inner peripheral portion; a front end side inner peripheral convex portion protruding on an inner peripheral side so as to come into contact with an outer peripheral portion of the annular member such that the front end side outer peripheral sealing portion is pushed outward in a radial direction, and a base end side inner peripheral convex portion formed on the inner peripheral side closer to the closing portion than the front end side inner peripheral convex portion so as to come into contact with the outer peripheral portion of the annular member such that the base end side outer peripheral sealing portion is pushed outward in the radial direction.Advantageous Effects of the InventionAccording to the cylinder device and the sealing member described above, an assembly property of the sealing ring can be improved.Brief Description of the DrawingsFIG. 1 is a cross-sectional view illustrating a cylinder device according to an embodiment of the present invention. FIG. 2 is a partially enlarged cross-sectional view illustrating an essential part of the cylinder device according to the embodiment of the present invention. FIG. 3 is a partially enlarged cross-sectional view illustrating a state during assembly of a sealing member and directed to the essential element of the cylinder device according to the embodiment of the present invention.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTIONAn embodiment of the present invention will be described below with reference to the accompanying drawings.A cylinder device 10 according to an embodiment shown in FIG. 1 is used for a suspension device of an automobile or a rail vehicle. The cylinder device 10 comprises a cylinder 11 in which a working fluid is sealed. The cylinder 11 has an inner tube 12 and an outer tube 13 having a diameter larger than that of the inner tube 12 and coaxially arranged so as to cover the inner tube 12. The cylinder 11 has a double tube structure in which a reservoir chamber 14 is formed between the inner tube 12 and the outer tube 13.A piston 17 is slidably fitted in the inner tube 12 of the cylinder 11. The piston 17 defines in the inner tube 12, i.e. in the cylinder 11, an upper chamber 18 and a lower chamber 19.Specifically, in the cylinder 11, hydraulic fluid serving as working fluid is sealed in the upper chamber 18 and the lower chamber 19, and hydraulic fluid serving as working fluid and gas are sealed in the reservoir chamber 14.A rod 22 is connected to the piston 17. A first side in the axial direction of the rod 22 is connected to the piston 17 inserted into the cylinder 11, and a second side in the axial direction protrudes outward from an end in the axial direction of the cylinder 11, i.e., from an end of the inner tube 12 and an end of the outer tube 13 (in an up / down direction, which will be referred to as a cylinder axial direction in FIG. 1 ). The piston 17 is fixed in the inner tube 12 by a nut 23 to an end portion of the rod 22, and moves together with the piston 17.An annular rod guide (an annular member) 25 and an annular sealing member 26 are coaxially disposed in the cylinder 11 on one end side in the cylinder axial direction in which the rod 22 protrudes. The seal member 26 is disposed farther outward in the cylinder on / off direction along the cylinder axial direction (in the up / down direction of FIG. 1, which will be referred to as a cylinder on / off direction hereinafter) than the rod guide 25 (on an upper side in the up / down direction in FIG. 1 ). In other words, the rod guide 25 is offset with respect to the sealing member 26 in the cylinder clean / out direction toward the cylinder inner side (i.e., a lower side in the up / down direction of FIG. 1 ). Opposite the rod guide 25 and the seal member 26 in the cylinder axial direction, a bottom valve 28 is disposed in the cylinder 11.The rod 22 is slidably inserted through the rod guide 25 and the seal member 26. An end portion of the rod 22 disposed in the cylinder 11 is positioned on a central axis of the cylinder 11 by the piston 17 disposed in the inner tube 12. In addition, an intermediate portion in the axial direction of the rod 22 is positioned on the central axis of the cylinder 11 by the rod guide 25 fitted in the cylinder 11. That is, the rod 22 is supported coaxially with the cylinder 11 by the piston 17 and the rod guide 25.The rod guide 25 movably supports the rod 22 in the axial direction while preventing movement in the radial direction. As a result, the rod guide 25 guides the movement of the rod 22, and the outer peripheral portion of the sealing member 26 is fitted into the outer tube 13 of the cylinder 11 with a fit. The rod 22 is inserted into the seal member 26 such that the rod 22 is fitted into an inner peripheral portion with a fit. Consequently, the sealing member 26 closes one end side of the cylinder 11 and restricts leakage of hydraulic fluid contained in the inner tube 12 as well as high-pressure gas and hydraulic fluid contained in the reservoir chamber 14 to the outside.The outer tube 13 of the cylinder 11 forms a bottomed substantially cylindrical shape having a cylindrical body portion 30, a bottom portion 31 configured to close an end portion opposite to a protruding side of the rod 22 in the body portion 30, and a closing portion 33 protruding inward in the radial direction from an opening portion 32 in the body portion 30 on a side to which the rod 22 protrudes.The inner tube 12 of the cylinder 11 has a cylindrical shape. One end side in the axial direction of the inner tube 12 is supported by fitting into a bottom body 34 of the bottom valve 28, which bottom valve is disposed in the bottom portion 31 of the outer tube 13, and the other end side in the axial direction is supported by fitting into the rod guide 25 fitted into the opening portion 32 of the outer tube 13.A through hole 35 passing through at a center in the radial direction is formed in the bottom body 34 of the bottom valve 28. A liquid passage 36 and a liquid passage 37 formed penetrating in the axial direction are formed in the bottom body 34 around the through hole 35. The liquid passage 36 and the liquid passage 37 are adapted to communicate between the lower chamber 19 in the inner tube 12 and the reservoir chamber 14 disposed between the outer tube 13 and the inner tube 12. A disk valve 38 is disposed on a bottom portion 31 side of the bottom body 34, and a disk valve 39 is disposed on an opposite side to the bottom portion 31. The disk valve 38, which is a retraction side damping valve, is adapted to open and close the liquid passage 36 in the bottom body 34 in the radial direction. The disk valve 39, which is a check valve, is capable of opening and closing the liquid passage 37 that is located farther outward in the radial direction of the bottom body 34 than the liquid passage 36. These disk valves 38 and 39 are fitted to the bottom body 34 by a rivet 42 which rivet is inserted and caulked in the through hole 35 of the bottom body 34.The disk valve 38 permits a flow of hydraulic fluid which flows through a through hole, not shown, formed in the disk valve 39 and the liquid passage 36 from the lower chamber 19 toward the reservoir chamber 14. To generate a damping force, the disk valve 38 adjusts a flow of hydraulic fluid. The disk valve 38 prevents hydraulic fluid flow in a reverse direction. That is, the disk valve 38 is a damping valve configured to generate a damping force when, when the rod 22 moves toward the retraction side and the piston 17 moves toward the lower chamber 19 for increasing pressure in the lower chamber 19, the liquid passage 36 is opened.The disk valve 39 permits hydraulic fluid flow from the reservoir chamber 14 via the fluid passage 37 to the lower chamber 19 without resistance. The disk valve 39 prevents hydraulic fluid flow in a reverse direction. The disk valve 39 opens the liquid passage 37 when the rod 22 moves toward an extension side and the piston 17 moves toward the upper chamber 18 to reduce the pressure in the lower chamber 19. The disk valve 39 is a suction valve that allows the hydraulic fluid to flow from the reservoir chamber 14 into the lower chamber 19 substantially without generating a damping force when the liquid passage 37 is opened.The rod 22 has a main shaft portion 45 having a constant diameter and an inner (inner) end shaft portion 46 at an end portion thereof inserted into the inner tube 12. The inner end shaft portion 46 has a smaller diameter than the main shaft portion 45, and an external thread 47 is formed on an opposite side of the main shaft portion 45. The nut 23 is screwed onto the external thread 47. The piston 17 and the disc valves 51 and 52 arranged on both sides thereof are connected to the rod 22 by the nut 23.In the piston 17, a through hole 53 passing in the axial direction is formed centrally in the radial direction. Around the through hole 53, liquid passages 54 and 55 passing in the axial direction are formed. The inner end shaft portion 46 of the rod 22 is inserted into the through hole 53. The liquid passage 54 and the liquid passage 55 are adapted to communicate between the lower chamber 19 disposed in the inner tube 12 closer to the bottom portion 31 than the piston 17 and the upper chamber 18 disposed in the inner tube 12 further on the opposite side of the bottom portion 31 than the piston 17.The piston 17 and the disk valve 52 are disposed on one side of the bottom portion 31, while the disk valve 51 is disposed on an opposite side with respect to the bottom valve 31. The disk valve 51 is a retraction-side damping valve configured to open and close the fluid passage 54 located outward in the radial direction of the piston 17. The disk valve 52 is an extension-side damping valve configured to open and close the liquid passage 55 located inward in the radial direction of the piston 17.The disk valve 51 permits hydraulic fluid flow from the lower chamber 19 to the upper chamber 18 but restricts hydraulic fluid flow in an opposite direction. The disk valve 51 opens the liquid passage 54 when the piston 22 moves toward a retraction side and the piston 17 moves toward the lower chamber 19 to increase the pressure in the lower chamber 19. The disk valve 51 generates a damping force when the liquid passage 54 is opened. That is, the disk valve 51 is a retraction side damping valve. The disk valve 52 allows hydraulic fluid flow from the upper chamber 18 side to the lower chamber 19, but restricts hydraulic fluid flow in an opposite direction. In order to increase the pressure of the upper chamber 18, the disk valve 52 opens the liquid passage 55 when the rod 22 moves toward the extension side and the piston 17 moves toward the upper chamber 18. The disk valve 52 generates a damping force when the liquid passage 55 is opened. That is, the disk valve 52 is an extension-side damping valve.Then, when the rod 22 moves toward the extension side to increase an amount of protrusion from the cylinder 11, a corresponding amount of hydraulic fluid flows through the liquid passage 37 from the reservoir chamber 14 toward the lower chamber 19, with the disk valve 39 of the bottom valve 28 opened. On the contrary, when the rod 22 moves toward the retraction side and an insertion amount into the cylinder 11 is increased, a corresponding hydraulic fluid flows from the lower chamber 19 to the reservoir chamber 14 via the liquid passage 36 with the disk valve 38 opened.The piston rod 25 is constituted by a rod guide main body 60 having a substantially step-like ring shape and a cylindrical collar 61 which is fitted and fixed to an inner peripheral portion of the rod guide main body 60. An outer peripheral side of the rod guide main body 60 has a shape in which an annular large-diameter outer peripheral portion 64 is formed on a first side in the axial direction, and a small-diameter outer peripheral portion 65 having a smaller diameter than the large-diameter outer peripheral portion 64 is formed on a second side in the axial direction. The large-diameter outer peripheral portion 64 and the small-diameter outer peripheral portion 65 are formed coaxially. In the rod guide main body 60, the large-diameter outer peripheral portion 64 is fitted into an outer peripheral portion 67 of the trunk portion 30 of the outer tube 13 of the cylinder 11. An inner peripheral surface 67 aformed by a cylinder surface located outward in the cylinder on / off direction is formed on the inner peripheral portion 67. In addition, an inner peripheral surface 67 bformed of an inclined surface having a diameter reducing toward the inside is formed on the inner peripheral portion 67 more inward in the cylinder on / off direction than the inner peripheral surface 67 a. In addition, an inner peripheral surface 67 cformed by a cylinder surface having a smaller diameter than that of the inner peripheral surface 67 ais formed at the inner peripheral portion 67 more inward in the cylinder on / off direction than the inner peripheral surface 67 b. An outer circumferential surface 64 aof the large-diameter outer circumferential portion 64 comes into contact with the entire circumference of the inner circumferential surface 67 cof the inner circumferential portion 67 when fitted in a defined position of the outer tube 13. In addition, the small diameter outer peripheral portion 65 of the rod guide main body 60 is fitted into an inner peripheral surface of an inner peripheral portion 69 of the inner tube 12 of the cylinder 11. At this time, the outer circumferential surface of the small-diameter outer circumferential portion 65 comes into contact with the inner circumferential surface of the inner circumferential portion 69 over the entire circumference.An inner peripheral side of the rod guide main body 60 has a shape in which an inner peripheral large diameter portion 72 is formed on one side of the outer peripheral large diameter portion 64 in the axial direction, and an inner peripheral small diameter portion 73 having a smaller diameter than the inner peripheral large diameter portion 73 is formed on one side of the outer peripheral small diameter portion 65 in the axial direction.An annular convex portion 75 having an annular shape protruding in the axial direction is formed at an end portion in the axial direction of the rod guide main body 60 on the side of the large diameter outer peripheral portion 64. The annular convex portion 75 has a tapered shape having a diameter decreasing as the outer peripheral portion 76 advances toward a front protruding side, and has a wedge shape having a diameter increasing as an inner peripheral portion 77 advances toward a front protruding side. As illustrated by a two-dot chain line in FIG. 2, in the outer peripheral portion 76 of the annular convex portion 75, an outer peripheral surface (a contact surface) 76 awhich is formed from an intermediate portion to a front end portion and constitutes a wedge surface is formed, and an outer peripheral surface 76 bwhich is formed at a base end portion in the protruding direction constitutes a cylindrical surface. As shown in FIG. 1, the inner circumferential surface of the inner circumferential portion 77 forms a wedge surface. The outer peripheral portion 76 and the inner peripheral portion 77 are coaxially arranged with the large-diameter outer peripheral portion 64, whereby the outer peripheral surfaces 76 aand 76 bof the outer peripheral portion 76 are coaxially arranged with the outer peripheral surface 64 aof the large-diameter outer peripheral portion 64.As illustrated in FIG. 2, a maximum outer diameter of the annular convex portion 75, i.e., an outer diameter of the outer circumferential surface 76 bhas a smaller diameter than an outer diameter of the outer circumferential surface 64 aof the large-diameter outer circumferential portion 64. Consequently, the outer peripheral portion 64 has a stepped surface 64 bperpendicular to the outer peripheral surfaces 64 aand 76 band is configured to connect the surfaces 64 aand 76 bbetween the outer peripheral surface 76 band the large-diameter outer peripheral portion 64. The stepped surface 64 bis disposed coaxially with the outer circumferential surfaces 76 aand 76 b.As shown in FIG. 1, a communication hole 81 passing in the axial direction is formed at a position inwardly offset in the radial direction with respect to the annular convex portion 75 in the rod guide main body 60. The communication hole 81 communicates with the reservoir chamber 14 disposed between the outer tube 13 and the inner tube 12. The collar 61 is fitted and attached to the small diameter inner peripheral portion 73 of the rod guide main body 60, and a main shaft portion 45 of the rod 22 is inserted into the collar 61 so as to come into sliding contact therewith.The outer peripheral side of the seal member 26 comes into contact with the inner peripheral annular portion 67 of the outer tube 13 and the annular rod guide 25 fitted in the inner peripheral portion 67 so as to seal the inner peripheral portion 67 of the outer tube 13. In addition, the inner peripheral portion of the seal member 26 comes into contact with the outer peripheral portion of the main shaft portion 45 of the rod 22 such that the outer peripheral portion of the main shaft portion 45 is sealed. Consequently, the sealing member 26 closes a space between the outer tube 13 and the main shaft portion 45 of the rod 22.The seal member 26 is an integrally formed product in which an annular member 86 is embedded in an elastic member 85. The elastic member 85 is formed of a rubber material having good sliding properties, such as nitrile rubber, fluoro rubber, or the like. The annular member 86 is formed of metal and has an annular shape. The annular member 86 maintains a shape of the sealing member 26. The circular tube-shaped member 86 generates a certain rigidity in the sealing member 26, which is conducive to mounting it in a target area.The sealing member 26 has an annular closing portion 88 formed by a portion of the elastic member 85 and the annular member 86, and further has an annular sealing ring 89 formed by a portion of the elastic member 85, and an annular check lip 90 formed by a portion of the elastic member 85. Since the seal member 26 is an integrally formed product, the seal ring 89 and the check lip 90 are integrally formed with the closure portion 88.The closing portion 88 is a portion that closes the opening portion 32 of the one end side of the cylinder in the cylinder axial direction of the cylinder 11. A seal portion 88 formed of the elastic member 85 is constituted by a dust lip 91, an oil lip 92, an inner peripheral liner portion 93, an outer peripheral seal 94, and an end surface seal 95. The closure region 88 is arranged coaxially in the cylinder 11 with respect to the rod guide 25.The dust lip 91 extends from an inner peripheral side of the annular member 86 so as to form a cylindrical shape in the cylinder clean / out direction. The inner peripheral portion of the dust lip 91 has a diameter that reduces in the cylinder clean / out direction in the outward direction. The oil lip 92 extends from the inner peripheral side of the annular member 86 so as to form a gutter-shaped shape in the cylinder clean / out direction. The inner peripheral portion of the oil lip 92 has a diameter that reduces as it runs down in the cylinder clean / out direction. The inner peripheral liner portion 93 connects the dust lip 91 and the oil lip 92 while covering an inner peripheral side of the annular member 86. The outer circumferential seal 94 covers the outer circumferential surface of the annular member 86 and forms a cylindrical shape. The end face seal 95 covers a surface of the annular member 86 that is buried in the cylinder clean / out direction. an annular spring 98 is disposed on an outer peripheral portion of the dust lip 91, and an annular spring 99 is disposed on an outer peripheral portion of the oil lip 92.The seal ring 89 is disposed along the cylinder on the outer circumferential side of the closing portion 88 along the cylinder on the outer circumferential side and is connected to the outer circumferential seal 94 and the end surface seal 95 of the closing portion 88. The seal ring 89 comes into communication with the outer circumferential surface 76 aof the outer circumferential portion 76 of the annular convex portion 75 of the rod guide 25 and the inner circumferential surface 67 aof the inner circumferential portion 67 of the outer tube 13 of the cylinder 11. That is, the outer peripheral surface 76 aand the inner peripheral surface 67 abecomes contact surfaces which come into contact with the seal ring 89, and the outer peripheral surface 76 abecomes an inclined surface. The check lip 90 forms an annular shape and extends from an intermediate portion in the radial direction of the inner surface seal 95, increasing its diameter as it goes in the direction of descending in the cylinder clean / out direction.The main shaft portion 45 of the rod 22 is inserted through the seal member 26 attached to the cylinder 11 inside the dust lip 91, the inner peripheral liner portion 93 and the oil lip 92. In this state, one end of the rod 22 extends outward from the sealing member 26.The spring 98 fitted into the dust lip 91 maintains a clamping force in a direction of adhering the dust lip 91 to the rod 92 at a constant level. In addition, the spring 98 is also used to adjust the clamping force for specific configurations. The spring 99 fitted into the oil lip 92 adjusts a clamping force in a direction of adhering the oil lip 92 to the rod 22. If the clamping forces of the dust lip 91 and the oil lip 92 satisfy the respective specifications alone, the springs 98 and 99 may be omitted. Further, only one of the springs 98 and 99 may be used.The check lip 90 holds a predetermined excess at a portion farther inward than the annular convex portion 75 of the rod guide 25 to ensure sealing contact over the entire circumference. Hydraulic fluid leaking from a gap between the rod guide 25 and the rod 22 is accumulated in a chamber 100 located closer to the gap than the check lip 90 The check lip 90 is opened when the pressure of the chamber 100 is higher than the pressure of the reservoir chamber 14 by a predetermined amount, causing the hydraulic fluid accumulated in the chamber 100 to flow into the reservoir chamber 14 via the communication hole 81. That is, the check lip 90 functions as a check valve configured such that flow of hydraulic oil and gas is possible only in one direction from the chamber 100 to the reservoir chamber 14 and flow in a reverse direction is restricted.An initial state of the seal ring 89 before being mounted to the cylinder device 10 will be described with reference to FIG. 2. Further, in FIG. 2, the large-diameter outer peripheral portion 64 and the outer peripheral portion 76 of the inner peripheral portion 67 of the outer tube 13 and the rod guide 25 are represented by a two-dot chain line in a state of being assembled to the cylinder device 10 with respect to the seal ring 89 in the initial state.The seal ring 89 includes a first outer peripheral sealing portion 101, a second outer peripheral sealing portion 102, a third outer peripheral sealing portion 103, a first inner peripheral abutting portion 104, a second inner peripheral abutting portion 105, and a third inner peripheral abutting portion 106.The first outer peripheral sealing portion 101 is formed on an outer peripheral side of a front end portion opposite to the sealing portion 88 in the seal ring 89. The second outer peripheral sealing portion 102 is formed in the seal ring 89 on an outer peripheral side of the intermediate portion closer to the closing portion 88 than the first outer peripheral sealing portion 101. The third outer peripheral sealing portion 103 is formed in the seal ring 89 on an outer peripheral side of the bottom-side end portion closer to the closing portion 88 than the second outer peripheral sealing portion 102. The first outer peripheral sealing portion 101, the second outer peripheral sealing portion 102, and the third outer peripheral sealing portion 103 each come into contact with the inner peripheral surface 67 aof the inner peripheral portion 67 of the outer tube 13. Consequently, the seal ring 89 is integrally formed with the outer peripheral side of the closing portion 88 so as to come into contact with the outer peripheral surface 67 aof the outer peripheral portion 67 of the outer tube 13.The first inner peripheral abutting portion 104 is formed in the seal ring 89 on an inner peripheral side of the front end portion opposite to the seal portion 88. The second inner peripheral abutting portion 105 is formed in the seal ring 89 on an inner peripheral side of the intermediate portion closer to the closing portion 88 than the first inner peripheral abutting portion 104. In the seal ring 89, the third inner peripheral abutting portion 106 is formed on an inner peripheral side of the base end portion closer to the closing portion 88 than the second inner abutting portion 105. The first inner peripheral abutting portion 104, the second inner peripheral abutting portion 105, and the third inner peripheral abutting portion 106 come into contact with the outer peripheral surface 76 aof the outer peripheral portion 76 of the annular convex portion 75 of the rod guide 25. Further, the first outer peripheral sealing portion 101, the second outer peripheral sealing portion 102, and the third outer peripheral sealing portion 103 should have a sealing function with respect to the inner peripheral surface 67 aof the inner peripheral portion 67 of the outer tube 13. However, the first inner peripheral abutting portion 104, the second inner peripheral abutting portion 105, and the third inner peripheral abutting portion 106 may abut against the outer peripheral surface 76 aof the outer peripheral portion 76 of the annular convex portion 75 of the rod guide 25, and may not have a sealing effect.The first outer peripheral sealing portion 101 and the first inner peripheral abutting portion 104 may overlap in a direction with respect to a central axis of the sealing member 26 (hereinafter referred to as a sealing axis) at positions (i.e., in the up / down direction in FIG. 2, which hereinafter is also referred to as a sealing axis direction). Consequently, the first outer peripheral sealing portion 101 and the first inner peripheral abutting portion 104 are formed at outer and inner positions which are opposed to each other in the radial direction of the seal ring 89. The second outer peripheral seal portion 102 and the second inner peripheral abutment portion 105 overlap each other at positions in the seal axis direction. Consequently, the second outer peripheral sealing portion 102 and the second inner peripheral abutting portion 105 are formed at outer and inner positions opposing each other in the radial direction of the seal ring 89. The third outer peripheral seal portion 103 and the third inner peripheral abutment portion 106 overlap each other at positions in the seal axis direction. Consequently, the third outer peripheral sealing portion 103 and the third inner peripheral abutting portion 106 are formed at outer and inner positions opposing each other in the radial direction of the seal ring 89. Although it is preferable that the outer peripheral seal portions and the inner peripheral abutment portions are opposed to each other at positions in the seal axis direction, this may not be the case because the sealing effect is deteriorated but is still present to a greater extent than the related art.A first outer peripheral convex portion 111 (a convex portion) protruding outward in the radial direction is formed on the first outer peripheral sealing portion 101. A second outer peripheral convex portion 112 (a convex portion) that protrudes outward in the radial direction is formed on the second outer peripheral sealing portion 102. A third outer peripheral sealing portion 113 (a convex portion) protruding outward in the radial direction is formed on the third outer peripheral sealing portion 103. The first outer peripheral convex portion 111 is formed on the first outer peripheral sealing portion 101 with respect to the sealing axis direction. The second outer peripheral convex portion 112 is formed on the second outer peripheral sealing portion 102 with respect to the sealing axis direction. The third outer peripheral convex portion 113 is formed on the third outer peripheral sealing portion 103 at a portion located near the second outer peripheral convex portion 112 in the sealing axis direction.The first outer peripheral convex portion 111 has a ring shape around a sealing axis. The first outer peripheral convex portion 111 has an outer peripheral surface 111 bfacing away from the closure portion 88 and an outer peripheral surface 111 afacing the closure portion 88. The outer peripheral surface 111 ais an inclined surface having a diameter that reduces as the distance from the shutter portion 88 in the sealing axis direction increases. The outer peripheral surface 111 bis an inclined surface having a diameter that reduces as the shutter portion 88 approaches in the sealing axis direction. The outer peripheral surface 111 aand the outer peripheral surface 111 bare connected. The connecting portions form a first maximum outer diameter region 111 cthat has a maximum outer diameter in the first outer circumferential convex region 111. The first maximum outer diameter portion 111 cis in a ring shape.The second outer peripheral convex portion 112 has a ring shape around the sealing axis. The second outer peripheral convex portion 112 has an outer peripheral surface 112 afacing away from the closure portion 88 and an outer peripheral surface 112 bfacing toward the closure portion 88. The outer peripheral surface 112 aincludes an inclined surface whose diameter decreases as the distance from the shutter portion 88 increases in the sealing axis direction. The outer peripheral surface 112 bis an inclined surface having a diameter that reduces as the shutter portion 88 approaches in the sealing axis direction. The outer peripheral surface 112 aand the outer peripheral surface 112 bare connected to each other. The connecting portions form a second maximum outer diameter region 112 cthat has a maximum outer diameter in the second outer circumferential convex region 112. The second maximum outer diameter portion 112 cis in a ring shape.The outer peripheral surface 111 bof the first outer peripheral convex portion 111 and the outer peripheral surface 112 aof the second outer peripheral convex portion 112 are connected to each other. A portion including the outer peripheral surface 111 bof the first outer peripheral convex portion 111 and a portion including the outer peripheral surface 112 aof the second outer peripheral convex portion 112 form a first outer peripheral concave portion 114 recessed inward in the radial direction. A boundary portion between the outer circumferential surface 111 band the outer circumferential surface 112 ais a first minimum outer diameter region 114 awhich has a minimum outer diameter in the first outer circumferential concave region 114. The first outer circumferential concave portion 114 also has a ring shape around the sealing axis.The third outer peripheral convex portion 113 has a ring shape around the sealing axis. The third outer peripheral convex portion 113 has an outer peripheral surface 113 afacing away from the closure region 88 and an outer peripheral surface 113 bfacing toward the closure region 88. The outer peripheral surface 113 aincludes an inclined surface having a diameter that reduces as the distance from the sealing portion 88 in the sealing axis direction increases. The outer peripheral surface 113 bis an inclined surface having a diameter that reduces as the closing portion 88 approaches in the sealing axis direction. The outer peripheral surface 113 aand the outer peripheral surface 113 bare connected. The connecting portions form a third maximum outer diameter region 113 chaving a maximum outer diameter in the third outer circumferential convex region 113. The third maximum outer diameter portion 113 cis in a ring shape.The outer peripheral surface 112 bof the second outer peripheral convex portion 112 and the outer peripheral surface 113 aof the third outer peripheral convex portion 113 are connected. A portion including the outer peripheral surface 112 bof the second outer peripheral convex portion 112 and a portion including the outer peripheral surface 113 aof the third outer peripheral convex portion 113 form a second outer peripheral concave portion 115 recessed inward in the radial direction. A boundary portion between the outer peripheral surface 112 band the outer peripheral surface 113 ais a second minimum outer diameter region 115 awhich has a minimum outer diameter in the second outer peripheral concave region 115. The second outer circumferential concave portion 115 further has a ring shape around the sealing axis.An outer peripheral surface 103 aconstitutes a cylindrical surface connecting the outer peripheral surface 113 bof the third outer peripheral convex portion 113, and an outer peripheral surface 94 aof the outer peripheral seal 94 is formed at the third outer peripheral sealing portion 103. By the outer peripheral surface 113 band the outer peripheral surface 103 a, a step difference portion 116 is formed on the third outer peripheral sealing portion 103, in which a side located on the closing portion 88 side is located more toward the inside in the sealing axis direction than the side farther from the sealing portion 88.The first maximum outer diameter portion 111 c, the second maximum outer diameter portion 112 c, and the third maximum outer diameter portion 113 chave the same diameter. The first maximum outer diameter portion 111 c, the second maximum outer diameter portion 112 c, and the third maximum outer diameter portion 113 chave a diameter larger than that of the inner circumferential surface 67 aof the outer tube 13 coming into contact therewith in the assembled state, so that there is an interference amount. The first maximum outer diameter portion 111 c, the second maximum outer diameter portion 112 c, and the third maximum outer diameter portion 113 care maximum outer diameter portions in the seal ring 89. Consequently, an outer diameter of the seal ring 89 is larger than an inner diameter of the inner circumferential surface 67 aof the inner circumferential portion 67 of the outer tube 13. the first outer circumferential convex portion 111, the second outer circumferential convex portion 112, and the third outer circumferential convex portion 113 protruding on the outer circumferential side respectively come into contact with the outer circumferential portion 67 of the outer tube 13, and press the first inner circumferential abutting portion 104, the second inner circumferential abutting portion 105, and the third inner circumferential abutting portion 106 inward in the radial direction. The first minimum outer diameter portion 114 aand the second minimum outer diameter portion 115 ahave the same diameter that is smaller than that of the inner circumferential surface 67 aof the outer tube 13.A first inner peripheral convex portion (a convex portion) 117 protruding inward in the radial direction is formed at the first inner peripheral abutting portion 104. A second inner peripheral convex portion (a convex portion) 118 protruding inward in the radial direction is formed on the second inner peripheral abutting portion 105. A third inner peripheral convex portion (a convex portion) 119 protruding inward in the radial direction is formed in a third inner peripheral abutting portion 106. The first inner peripheral convex portion 117 is formed on the first inner peripheral abutting portion 104 with respect to the sealing axis direction. The second inner peripheral convex portion 118 is formed on the second inner peripheral abutting portion 105 with respect to the sealing axis direction. The third inner peripheral convex portion 119 is formed to the third inner peripheral abutting portion 106 in a portion on a second inner peripheral convex portion 118 side in the sealing axis direction.The first inner peripheral convex portion 117 has a ring shape around the sealing axis. The first inner peripheral convex portion 117 has an inner peripheral surface 117 afacing away from the closure portion 88 and an inner peripheral surface 117 bfacing toward the closure portion 88. The inner circumferential surface 117 ais an inclined surface having a diameter that increases as the distance from the sealing portion 88 increases in the sealing axis direction. The inner circumferential surface 117 bis an inclined surface having a diameter that increases in the sealing axis direction as the sealing portion 88 is approached. The inner peripheral surface 117 aand the inner peripheral surface 117 bare connected to each other. The connecting portions form a first minimum inner diameter portion 117 chaving a minimum inner diameter in the first inner peripheral convex portion 117. The first minimum inner diameter portion 117 cis in a ring shape.A portion of the inner peripheral surface 117 aof the first inner peripheral convex portion 117 facing away from the shutter portion 88 and a portion of the outer peripheral surface 111 aof the first outer peripheral convex portion 111 facing away from the shutter portion 88 are connected to each other. These portions form a frontmost end portion 89a which is spaced furthest from the closure region 88 in the sealing ring 89. A diameter of the most-forward-located portion 89 ais smaller than that of the maximum outer diameter regions 111 c, 112 c, and 113 cand smaller than that of the minimum outer diameter regions 114 aand 115 a.Around the sealing axis, the second inner peripheral convex portion 118 has a ring shape. The second inner peripheral convex portion 118 has an inner peripheral surface 118 afacing away from the closure portion 88 and an inner peripheral surface 118 bfacing toward the closure portion 88. The inner circumferential surface 118 ais an inclined surface having a diameter that increases as the distance from the shutter portion 88 in the sealing axis direction increases. The inner circumferential surface 118 bis an inclined surface having a diameter that increases as the closing portion 88 approaches in the sealing axis direction. The inner peripheral surface 118 aand the inner peripheral surface 118 bare connected to each other. The connecting portions form a second minimum inner diameter region 118 chaving a minimum inner diameter in the second inner circumferential convex region 118. The second minimum inner diameter portion 118 cis in a ring shape.The inner circumferential surface 117 bof the first inner circumferential convex portion 117 and the inner circumferential surface 118 aof the second inner circumferential convex portion 118 are connected to each other. A portion including the inner circumferential surface 117 bof the first inner circumferential convex portion 117 and a portion including the inner circumferential surface 118 aof the second inner circumferential convex portion 118 form a first inner circumferential concave portion 120 recessed outward in the radial direction. A boundary portion between the inner circumferential surface 117 band the inner circumferential surface 118 ais a first maximum inner diameter region 120 athat has a maximum inner diameter in the first inner circumferential concave region 120. The first inner peripheral concave portion 120 further has a ring shape around the sealing axis.The third inner circumferential concave portion 119 has a ring shape around the sealing axis. The third inner peripheral convex portion 119 has an inner peripheral surface 119 afacing away from the closure portion 88 and an inner peripheral surface 119 bfacing toward the closure portion 88. The inner peripheral surface 119 ais an inclined surface having a diameter that increases as the distance from the sealing portion 88 in the sealing axis direction increases. The inner circumferential surface 119 bis an inclined surface having a diameter that increases as the sealing portion 88 is approached in the sealing axis direction. The inner peripheral surface 119 aand the inner peripheral surface 119 bare connected to each other. The connecting portions form a third minimum inner diameter portion 119 chaving a minimum inner diameter in the third inner peripheral convex portion 119. The third minimum inner diameter portion 119 cis in a ring shape.The inner circumferential surface 118 bof the second inner circumferential convex portion 118 and the inner circumferential surface 119 aof the third inner circumferential convex portion 119 are connected to each other. A portion including the inner circumferential surface 118 bof the second inner circumferential convex portion 118 and a portion including the inner circumferential surface 119 aof the third inner circumferential convex portion 119 form a second inner circumferential concave portion 121 recessed outward in the radial direction. A boundary portion between the inner peripheral surface 118 band the inner peripheral surface 119 bis a second maximum inner diameter region 121 awhich has a maximum inner diameter in the second inner peripheral concave region 121. The second inner peripheral concave portion 121 also has a ring shape around the sealing axis.A curved inner peripheral surface 106 aconnecting the inner peripheral surface 119 bof the third inner peripheral convex portion 119 and a surface 95 aof the end surface seal 95 is formed at the third inner peripheral abutting portion 106. A portion including the inner circumferential surface 119 bof the third inner circumferential convex portion 119 and a portion including the curved inner circumferential surface 106 aof the third inner circumferential abutting portion 106 form a third inner circumferential concave portion 122 recessed outward in the radial direction. The third inner circumferential concave portion 122 also has a ring shape around the sealing axis.The second minimum diameter portion 118 cis smaller in diameter than the first minimum diameter portion 117 c. The third minimum inner diameter portion 119 cis smaller in diameter than that of the second minimum inner diameter portion 118 c. The second maximum inner diameter portion 121 ahas a smaller diameter than that of the first maximum inner diameter portion 120 a. In the embodiment, the first minimum inner diameter portion 117 c, the second minimum inner diameter portion 118 c, and the third minimum inner diameter portion 119 care disposed on the same inclined surface, for example.The first minimum inner diameter portion 117 cis smaller in diameter than an outer diameter of a portion of the outer peripheral portion 76 of the rod guide 25 with which the first minimum inner diameter portion 117 cmoves positionally in the sealing axis direction. The second minimum inner diameter portion 118 cis smaller in diameter than an outer diameter of a portion of the outer peripheral portion 76 of the rod guide 25 with which the second minimum inner diameter portion 118 ccoincides in position in the sealing axis direction. The third minimum inner diameter portion 119 cis smaller than an outer diameter of a portion of the outer peripheral portion 76 of the rod guide 25 with which the third minimum inner diameter portion 119 cmoves positionally in the sealing axis direction. A diameter difference between the portion of the outer peripheral portion 76 with which the second minimum diameter portion 118 cin the sealing axis direction coincides in position and the second minimum inner diameter portion 118 cis larger than a diameter difference between the first minimum inner diameter portion 117 cand the portion of the outer peripheral portion 76 with which the first minimum inner diameter portion 117 cin the position in the sealing axis direction coincides. A diameter difference between the portion of the outer peripheral portion 76 with which the third minimum inner diameter region 119 cis coincident in the position of a sealing axis direction and the third minimum inner diameter region 119 cis larger than a diameter difference between the second minimum inner diameter region 118 cand the portion of the outer peripheral portion 76 with which the second minimum inner diameter region 118 cis coincident in the position of the sealing axis direction.The first inner peripheral convex portion 117, the second inner peripheral convex portion 118, and the third inner peripheral convex portion 119 protruding on the inner peripheral side come into contact with the outer peripheral portion 76 of the rod guide 25 so as to press the first outer peripheral sealing portion 101, the second outer peripheral sealing portion 102, and the third outer peripheral sealing portion 103 outward in the radial direction. An inclination amount (an outer diameter difference per unit length) of the inclined surface including the first minimum inner diameter portion 117 c, the second minimum inner diameter portion 118 c, and the third minimum inner diameter portion 119 cis larger than that of the outer circumferential surface 76 aof the outer circumferential portion 76 of the rod guide 25.The first maximum outer diameter portion 111 cand the first minimum inner diameter portion 117 clap in the sealing axis direction at one position. Consequently, the first outer peripheral convex portion 111 and the first inner peripheral convex portion 117 overlap at this position in the axial direction. The second maximum outer diameter portion 112 cand the second minimum outer diameter portion 118 clap at a position in the sealing axis direction. Consequently, the second outer peripheral convex portion 112 and the second inner peripheral convex portion 118 overlap at that position in the sealing axis direction. The third maximum outer diameter portion 113 cand the third minimum inner diameter portion 119 clap at a position in the sealing axis direction. Consequently, the third outer peripheral convex portion 113 and the third inner peripheral convex portion 119 coincide at that position in a sealing axis direction.When the first outer peripheral sealing portion 101 becomes a front end side outer peripheral sealing portion formed on a side of the seal ring 89 opposite from the closing portion 88, the second outer peripheral sealing portion 102 and the third outer peripheral sealing portion 103 become a bottom end side outer peripheral sealing portion formed closer to the closing portion 88 than the front end side outer peripheral sealing portion. In this case, the first outer peripheral convex portion 111 formed on the first outer peripheral sealing portion 101 becomes a front end side outer peripheral convex portion formed on the front end side outer peripheral sealing portion, and the second outer peripheral convex portion 112 and the third outer peripheral convex portion 113 formed on the second outer peripheral sealing portion 102 and on the third outer peripheral sealing portion 103 become a bottom end side outer peripheral convex portion formed on the bottom end side outer peripheral sealing portion.When the second outer peripheral sealing portion 102 becomes a front end side outer peripheral sealing portion disposed on a side of the seal ring 89 opposite to the closing portion 88, the third outer peripheral sealing portion 103 becomes a base end side outer peripheral sealing portion formed closer to the closing portion 88 than the front end side outer peripheral sealing portion. In this case, the second outer peripheral convex portion 112 formed on the second outer peripheral sealing portion 102 becomes a front end side outer peripheral convex portion formed on the front end side outer peripheral sealing portion, and the third outer peripheral convex portion 113 formed on the third outer peripheral sealing portion 103 becomes a bottom end side outer peripheral convex portion formed on the base end side outer peripheral sealing portion.When the first inner peripheral abutting portion 104 becomes a front end side inner peripheral abutting portion formed on a side of the seal ring 89 opposite to the closing portion 88, the second inner peripheral abutting portion 105 and the third inner peripheral abutting portion 106 become base end side inner peripheral abutting portions formed closer to the closing portion 88 than the front end side inner peripheral abutting portion.In this case, the first inner peripheral convex portion 117 formed on the first inner peripheral abutting portion 104 becomes a front end side inner peripheral convex portion formed on the front end side inner peripheral abutting portion, and the second inner peripheral convex portion 118 and the third inner peripheral convex portion 119 formed on the second inner peripheral abutting portion 105 and the third inner peripheral abutting portion 106 become a base end side inner peripheral convex portion formed on the base end side peripheral abutting portion.When the second inner peripheral abutting portion 105 becomes a front end side inner peripheral abutting portion formed on a side opposite from the closing portion 88, the third inner peripheral abutting portion 106 becomes a base end side inner peripheral abutting portion formed closer to the closing portion 88 than the front end side inner peripheral abutting portion. In this case, the second inner peripheral convex portion 118 formed on the second inner peripheral abutting portion 105 becomes a front end side inner peripheral convex portion formed on the front end side inner peripheral abutting portion, and the third inner peripheral convex portion 119 formed on the third inner peripheral abutting portion 106 becomes a base end side inner peripheral convex portion formed on the base end side inner peripheral abutting portion.When the sealing member 26 is mounted to the cylinder 11, in a preceding step, the bottom valve 28 is disposed on the bottom portion 31 of the outer tube 13, and the inner tube 12 is fitted into the bottom valve 28 in a state where the locking portion 33 of the outer tube 13 is aligned with the trunk portion 30. In addition, the rod 22 to which the piston 17 is attached makes the piston 17 fit into the inner tube 12. In addition, the rod guide 25 is fitted on the rod 22, and the rod guide 25 makes the small-diameter outer peripheral portion 65 fit into the inner tube 12 and the large-diameter outer peripheral portion 64 fit into the outer tube 13. In this way, the rod guide 25 is positioned with respect to the outer tube 13.When the sealing member 26 is assembled to the cylinder 11, the sealing member 26 is fitted into the outer tube 13 of the cylinder 11 in the above-described state including the sealing ring 89. Then, as shown in FIG. 3, the seal ring 89 is fitted between the outer peripheral portion 76 of the annular convex portion 75 of the rod guide 25 and the inner peripheral portion 67 of the outer tube 13. Thus, in the seal ring 89, the first outer peripheral convex portion 111, the second outer peripheral convex portion 112, and the third outer peripheral convex portion 113 are fitted into the inner peripheral surface 67 aof the inner peripheral portion 67. Then, the first maximum outer diameter portion 111 c, the second maximum outer diameter portion 112 c, and the third maximum outer diameter portion 113 ccomes in contact with the inner circumferential surface 67 aand are pressed by the inner circumferential portion 67 to come into a state of being elastically deformed inward in the radial direction, i.e., a compression direction.As described above, an inclination value of the inclined surface including the first minimum inner diameter portion 117 cof the first inner peripheral convex portion 117, the second minimum inner diameter portion 118 cof the second inner peripheral convex portion 118, and the third minimum inner diameter portion 119 cof the third inner peripheral convex portion 119 is larger than the outer peripheral surface 76 aof the outer peripheral portion 76 of the rod guide 25 with which they come into contact. For this reason, as shown in FIG. 3, when the seal ring 89 is inserted between the outer peripheral portion 76 of the annular convex portion 75 of the rod guide 25 and the inner peripheral portion 67 of the outer tube 13, first, the third inner peripheral convex portion 119 of the third inner peripheral abutting portion 106 comes into contact with the outer peripheral surface 76 aof the outer peripheral portion 76 of the rod guide 25 in the third minimum inner diameter portion 119 c. As the insertion of the seal ring 89 proceeds further from this state, the third inner peripheral convex portion 119 is pushed outward by the outer peripheral surface 76 aof the outer peripheral portion 76 of the rod guide 25 so as to be elastically deformed outward gradually in the radial direction, i.e., the compression direction.When the insertion further proceeds after the contact of the third minimum inner diameter portion 119 cwith the outer circumferential surface 76 of the rod guide 25, the second inner circumferential convex portion 118 of the second inner circumferential abutting portion 105 comes into a contact state with the outer circumferential surface 76 aof the outer circumferential portion 76 of the rod guide 25 in the second minimum inner diameter portion 118 c. As the insertion of the seal ring 89 proceeds further from this state, the second inner peripheral convex portion 118 is pushed outward in the radial direction by the outer peripheral surface 76 aof the outer peripheral portion 76 of the rod guide 25 so as to be gradually elastically deformed outward in the radial direction, i.e., in the compression direction.When the insertion further proceeds after the contact of the second minimum inner diameter portion 118c with the outer peripheral portion 76 of the rod guide 25, the first inner peripheral convex portion 117 of the first inner peripheral abutting portion 104 comes into a state of contact with the outer peripheral surface 76a of the outer peripheral portion 76 of the rod guide 25 in the first minimum inner diameter portion 117c. When the insertion of the seal ring 89 proceeds further from this state, the first inner peripheral convex portion 117 is pressed radially outward by the outer peripheral surface 76 aof the outer peripheral portion 76 of the rod guide 25 so as to elastically deform gradually outward in the radial direction, i.e., in the compression direction.Then, the first outer peripheral convex portion 111, the second outer peripheral convex portion 112, and the third outer peripheral convex portion 113 are each elastically deformed in the compression direction such that the first outer peripheral sealing portion 101, the second outer peripheral sealing portion 102, and the third outer peripheral sealing portion 103 are gap-free to adhere to the inner peripheral surface 67 aof the inner peripheral portion 67 of the outer tube 13, and the first inner peripheral convex portion 117, the second inner peripheral convex portion 118, and the third inner peripheral convex portion 119 are deformed in the compression direction such that the first inner peripheral abutting portion 104, the second inner peripheral abutting portion 105, and the third inner peripheral abutting portion 106 are gap-free to adhere to the outer peripheral surface 76 aof the outer peripheral portion 76 of the rod guide 25. In this state, the first outer peripheral convex portion 111, the second outer peripheral convex portion 112, and the third outer peripheral convex portion 113 press the first inner peripheral abutting portion 104, the second inner peripheral abutting portion 105, and the third inner peripheral abutting portion 106 inward in the radial direction to assume such a state as to be pressed against the outer peripheral surface 76 aof the outer peripheral portion 76 of the rod guide 25. In addition, the first inner peripheral convex portion 117, the second inner peripheral convex portion 118, and the third inner peripheral convex portion 119 press the first outer peripheral sealing portion 101, the second outer peripheral sealing portion 102, and the third outer peripheral sealing portion 103 outward in the radial direction to assume a state of being pressed against the inner peripheral surface 67 aof the inner peripheral portion 67 of the outer tube 13.Accordingly, when the seal ring 89 is inserted between the outer peripheral portion 76 of the rod guide 25 and the inner peripheral portion 67 of the outer tube 13 before a state is entered in which the second inner peripheral convex portion 118 of the second inner peripheral abutting portion 105 comes into contact with the rod guide 25 and the second outer peripheral convex portion 112 of the second outer peripheral sealing portion 102 comes into contact with the inner peripheral portion 67 of the outer tube 13, the third inner peripheral convex portion 119 of the third inner peripheral abutting portion 106 comes into contact with the rod guide 25, and the third outer peripheral convex portion 113 of the third outer peripheral sealing portion 103 comes into contact with the inner peripheral portion 67 of the outer tube 13. In addition, before a state is assumed in which the first inner peripheral convex portion 117 of the first inner peripheral abutting portion 104 comes into contact with the rod guide 25 and the first outer peripheral convex portion 111 of the first outer peripheral sealing portion 101 comes into contact with the inner peripheral portion 67 of the outer tube 13, the second inner peripheral convex portion 118 of the second inner peripheral abutting portion 105 comes into contact with the rod guide 25, and the second outer peripheral convex portion 112 of the second outer peripheral sealing portion 102 comes into contact with the inner peripheral portion 67 of the outer tube 13.When the sealing member 26 is disposed in the outer tube 13 as described above, a protruding portion of the outer tube 13, which is disposed opposite to the bottom portion 31 of the trunk portion 30, is bent inward from the trunk portion 30, to then form the locking portion 33. A portion of the lock portion 33 in which the annular member 86 is disposed in the radial direction of the shutter portion 88 is sandwiched between the annular convex portion 75 of the rod guide 25 and the annular member 86. Thus, the sealing member 26 is mounted on the cylinder 11.Even if the first minimum inner diameter portion 117 c, the second minimum inner diameter portion 118 c, and the third minimum inner diameter portion 119 care not disposed on the same inclined surface, the inclined surface inclination value including the first minimum inner diameter portion 117 cand the second minimum inner diameter portion 118 cand the inclined surface inclination value including the second minimum inner diameter portion 118 cand the third minimum inner diameter portion 119 cmay be larger than the inclined surface inclination value 76 aof the outer peripheral portion 76 of the rod guide 25. That is, an inclination value of all combinations of the inner peripheral convex portions adjacent to each other in the sealing axis direction may be larger than the inclination value of the inclined surface with which the convex portions contact.The cylinder device according to the above-mentioned JP 2011-52 732 A includes: an annular closing portion formed on a cover located farther outward in the cylinder radial direction than the rod guide so as to close an end side of the cylinder; and an annular seal ring formed inward in the cylinder radial direction with respect to the outer circumferential side of the closing portion so as to come into contact with an inclined outer circumferential portion of the rod guide and an inner circumferential portion of the cylinder. The seal ring is pressed into the inclined outer peripheral portion and the inner peripheral portion of the cylinder so as to be elastically deformed in the radial direction, i.e., in the compression direction, so as to adhere to the inclined outer peripheral portion and the inner peripheral portion so as to perform sealing with respect to the gap therebetween. In such a structure, in order to improve the sealing performance of the outer peripheral portion of the rod guide and the inner peripheral portion of the cylinder, it is considered to increase a volume of the seal ring. However, when the volume of the seal ring is increased, it may become difficult to insert the seal ring into the gap, and assembly to the cylinder device may be difficult.On the other hand, in the cylinder device according to the embodiment, the first outer peripheral convex portion 111 protruding in the radial direction is formed at the first outer peripheral sealing portion 101. The second outer peripheral convex portion 112 protruding in the radial direction is formed at the second outer peripheral sealing portion 102. The third outer peripheral convex portion 113 protruding in the radial direction is formed at the third outer peripheral sealing portion 103. In addition, the first inner peripheral convex portion 117 protruding in the radial direction is formed at the first inner peripheral abutting portion 104. The second inner peripheral convex portion 118 protruding in the radial direction is formed at the second inner peripheral abutting portion 105. The third inner peripheral convex portion 119 protruding in the radial direction is formed at the third inner peripheral abutting portion 106. Although the sealing effect is improved by partially increasing the volume in the seal axis direction, an increase in the frictional resistance of the outer tube 13 to the inner peripheral portion 67 and a frictional resistance of the rod guide 25 to the outer peripheral portion 76 can be suppressed. Consequently, the mounting properties of the sealing member 26 including the seal ring 89 can be improved.In addition, the first outer peripheral convex portion 111, the second outer peripheral convex portion 112, and the third outer peripheral convex portion 113 are formed, which are plural steps. In addition, the first inner peripheral convex portion 117, the second inner peripheral convex portion 118, and the third inner peripheral convex portion 119 are formed, which are plural steps. For this reason, even if foreign matters such as debris or the like enter between the seal ring 89 and the inner peripheral portion 67 of the outer tube 13 or the outer peripheral portion 76 of the rod guide 25, a portion affected by the foreign matters can be separated from a portion not affected by the foreign matters. For example, when one of the first outer peripheral convex portion 111, the second outer peripheral convex portion 112, and the third outer peripheral convex portion 113 is deformed by the foreign matter, two convex portions are unaffected and can ensure the sealing effect. If one of the first inner peripheral convex portion 117, the second inner peripheral convex portion 118, and the third inner peripheral convex portion 119 is deformed by the foreign matter, the remaining two unaffected convex portions can similarly ensure the sealing effect. The introduction of foreign matters is extremely rare, and even if foreign matters lowering the sealing effect of the seal ring are introduced, the foreign matters can be found by a checking process before delivery. Since a cylinder device in which the sealing effect of the seal ring is lowered cannot be supplied, this results in a reduction in the gain. In the cylinder device 10 according to the embodiment, since there is no decrease in the sealing effect of the seal ring 89 even when a foreign matter is introduced, the gain can be increased. Further, even when foreign matters are introduced, the foreign matters can be held at the first outer peripheral concave portion 114 and the second outer peripheral concave portion 115, preventing a decrease in sealing performance of the seal ring 89.In addition, the first inner peripheral convex portion 117 is formed at the first inner peripheral abutting portion 104. The second inner peripheral convex portion 118 is formed at the second inner peripheral abutting portion 105. The third inner peripheral convex portion 119 is formed at the third inner peripheral abutting portion 106. The first inner peripheral convex portion 117, the second inner peripheral convex portion 118, and the third inner peripheral convex portion 119 abut against the outer peripheral portion 76 of the rod guide 25 such that the first outer peripheral sealing portion 101, the second outer peripheral sealing portion 102, and the third outer peripheral sealing portion 103 are pressed outward in the radial direction. For this reason, an adhesion level of the first outer peripheral sealing portion 101, the second outer peripheral sealing portion 102, and the third outer peripheral sealing portion 103 to the inner peripheral portion 67 of the outer tube 13 can be increased. Consequently, the tightness of the outer tube 13 toward the inner peripheral portion 67 side can be improved.When the seal ring 89 is inserted between the inner peripheral portion 67 of the outer tube 13 and the outer peripheral portion 76 of the rod guide 25 before a state exists in which the second inner peripheral convex portion 118 of the second inner peripheral abutting portion 105 comes into contact with the rod guide 25 and the second outer peripheral convex portion 112 of the second outer peripheral sealing portion 102 comes into contact with the inner peripheral portion 67 of the outer tube 13, the third inner peripheral convex portion 119 of the third inner peripheral abutting portion 106 located closer to the base end comes into contact with the rod guide 25 and the third outer peripheral convex portion 113 of the third outer peripheral sealing portion 103 comes into contact with the inner peripheral portion 67 of the outer tube 13. Before a state is assumed in which the first inner peripheral convex portion 117 of the first inner peripheral abutting portion 104 comes into contact with the rod guide 25 and the first outer peripheral convex portion 111 of the first outer peripheral sealing portion 101 comes into contact with the inner peripheral portion 67 of the outer tube 13, the second inner peripheral convex portion 118 of the second inner peripheral abutting portion 105, which is disposed closer than the above at the base end, comes into contact with the rod guide 25 and the second outer peripheral convex portion 112 of the second outer peripheral sealing portion 102 comes into contact with the inner peripheral portion 67 of the outer tube 13. For this reason, when the sealing member 26 is assembled, the seal ring 89 can be smoothly inserted between the inner peripheral portion 67 of the outer tube 13 and the outer peripheral portion 76 of the rod guide 25. That is, premature deformation of the front end side of the seal ring 89 by hooking to the outer peripheral portion 76 of the rod guide 25 can be prevented. Consequently, the sealing effect can be further improved.In addition, when the seal ring 89 is inserted between the inner peripheral portion 67 of the outer tube 13 and the outer peripheral portion 76 of the rod guide 25, the inner peripheral convex portion 119 is compressed and deformed before the second inner peripheral convex portion 118. Consequently, the second inner peripheral convex portion 118 and the first inner peripheral convex portion 117 are advanced forward in front of the third inner peripheral convex portion 119. Likewise, when the second inner peripheral convex portion 118 is compressed and deformed before the first inner peripheral convex portion 117, the first inner peripheral convex portion 117 is advanced forward of the second inner peripheral convex portion 118. Consequently, with the seal ring 89 properly inserted between the inner peripheral portion 67 of the outer tube 13 and the outer peripheral portion 76 of the rod guide 25, the interference is increased. Consequently, the sealing effect can be further improved.If no sealing effect is obtained in the first inner peripheral abutting portion 104, the second inner peripheral abutting portion 105, and the third inner peripheral abutting portion 106, the assembling properties can be further improved.In addition, the first outer peripheral convex portion 111 is formed at the first outer peripheral sealing portion 101. The second outer peripheral convex portion 112 is formed at the second outer peripheral sealing portion 102. The third outer peripheral convex portion 113 is formed at the third outer peripheral sealing portion 103. The first outer peripheral convex portion 111, the second outer peripheral convex portion 112, and the third outer peripheral convex portion 113 may come into contact with the inner peripheral portion 67 of the outer tube 13 such that the first inner peripheral abutting portion 104, the second inner peripheral abutting portion 105, and the third inner peripheral abutting portion 106 are pressed inward in the radial direction. For this reason, an adhering degree of the first inner peripheral abutting portion 104, the second inner peripheral abutting portion 105, and the third inner peripheral abutting portion 106 to the outer peripheral portion 76 of the rod guide 25 is increased. Consequently, the sealing effect of the rod guide 25 on a side of the outer peripheral portion 76 can be enhanced.Further, since the seal ring 89 is formed integrally with the seal portion 88, the seal ring 89 can be mounted simultaneously with the seal portion 88. Consequently, assembly becomes easier.Since the outer diameter of the seal ring 89 is larger than the inner diameter of the inner peripheral portion 67 of the outer tube 13, a degree of adhesion of the seal ring 89 to the inner peripheral portion 67 of the outer tube 13 can be increased, whereby the sealing of the inner tube 13 to the inner peripheral portion 67 side can be improved.In addition, the outer peripheral surface 76 a, which serves as a contact surface of the rod guide 25 with the seal ring 89, is an inclined surface. For this reason, a structure in which the third inner peripheral convex portion 119 comes into contact with the rod guide 25 before the second inner peripheral convex portion 118 comes into contact with the rod guide 25, and the second inner peripheral convex portion 118 comes into contact with the rod guide 25 before the first inner peripheral convex portion 117 comes into contact with the rod guide 25 can be easily realized.While the seal ring 89 and the closing portion 88 have been provided as an integral seal member 26 in the above-described embodiment, the seal ring 89 and the closing portion 88 may be separate members. While all the outer peripheral sealing portions 101- 103 and the inner peripheral abutting portions 104- 106 have a configuration in which the convex portions protrude in the radial direction, at least one of the outer peripheral sealing portions 101- 103 and the inner peripheral abutting portions 104- 106 may have a convex portion protruding in the radial direction. That is, the embodiment may be modified in that the inner peripheral convex portions 117- 119 are formed on the inner peripheral abutting portions 104- 106 without the outer peripheral convex portions 111- 113 being formed on the outer peripheral sealing portions 101- 103, or the outer peripheral convex portions 111- 113 are formed on the outer peripheral sealing portions 101- 103 without the inner peripheral convex portions 117- 119 being formed on the inner peripheral abutting portions 104- 106. Needless to say, the outer peripheral convex portions are not reduced to these three locations, but may be provided at two or four or more locations as long as the convex portions are provided at a plurality of locations. The inner peripheral convex portions are also not limited to the three locations, but may be provided at two or four or more locations as long as the convex portions are provided at multiple locations. In addition, although the rod guide 25 configured to guide the rod 22 has been exemplified as an annular member that comes into contact with the seal ring 89, an annular member that does not come into contact with the rod 22, such as a captured seal or the like, may be similarly provided.While a dual cylinder type hydraulic shock absorber has been shown as a cylinder device in the above-described embodiment, the present invention can be applied to a cylinder device such as a single cylinder type hydraulic shock absorber or an active suspension device or the like. Further, the present invention can also be applied to a cylinder device such as a gas pressure shock absorber or the like. In addition, the present invention can be applied to a cylinder device of the type in which rods project from both sides in the axial direction of the cylinder. That is, the present invention can be applied to a cylinder device of any type in which a rod protrudes from at least one end of the cylinder.According to the above-described embodiment, the cylinder device includes a cylinder in which a working fluid is sealed, a rod protruding from at least one end of the cylinder, an annular member formed on one end side of the cylinder, an annular closing portion formed more outward in a cylinder on / off direction than the annular member so as to close the one end side of the cylinder, and an annular seal ring disposed inwardly from an outer circumferential side of the closing portion in the cylinder on / off direction so as to come into contact with an outer circumferential portion of the annular member and an inner circumferential portion of the cylinder. The seal ring includes a front end side outer peripheral seal portion formed on an outer peripheral side opposite to the closing portion so as to come into contact with the inner peripheral portion of the cylinder, a base end side outer peripheral seal portion formed on an outer peripheral side closer to the closing portion than the front end side outer peripheral seal portion so as to come into contact with the inner peripheral portion of the cylinder, a front end side inner peripheral abutting portion formed on the inner peripheral side opposite to the closing portion so as to come into contact with the outer peripheral portion of the annular member, and a base end side inner peripheral abutting portion formed on the inner peripheral side closer to the closing portion than the front end side inner peripheral abutting portion so as to come into contact with the outer peripheral portion of the annular member.At least one set of seal or abutment portions of the front end side outer circumferential seal portion and the base end side outer circumferential seal portion, and the front end side circumferential abutment portion and the base end side circumferential abutment portion is formed by convex portions protruding in a radial direction. Since the volume in the axial direction is sectionally increased, an increase in a sliding resistance with respect to the inner peripheral portion of the cylinder and a sliding resistance with respect to the outer peripheral portion of the annular member can be suppressed even if the sealing effect is improved. Consequently, an assembly property of the seal ring can be improved.Further, the convex portions are: a front end side inner peripheral convex portion formed at the front end side inner peripheral abutting portion; and a base end side inner peripheral convex portion formed at the base end side inner peripheral abutting portion. The convex portions come into contact with the outer peripheral portion of the annular member such that the front end side outer peripheral sealing portions and the base end side outer peripheral sealing portions are pushed outward in the radial direction. For this reason, an adhesion degree of the front end side outer circumferential sealing portion and the base end side outer circumferential sealing portion to the inner circumferential portion of the cylinder is increased. Consequently, sealing on the inner peripheral portion side of the cylinder can be improved.Further, shapes of the seal ring are formed such that, when the seal ring is inserted between the outer peripheral portion of the annular member and the inner peripheral portion of the cylinder, the base-end-side inner peripheral convex portion comes into contact with the annular member before the front-end-side inner peripheral convex portion comes into contact with the annular member. For this reason, the seal ring can be easily inserted between the inner peripheral portion of the cylinder and the outer peripheral portion of the annular member during assembly.Further, the shapes of the seal ring are formed such that, when the seal ring is inserted between the outer peripheral portion of the annular member and the inner peripheral portion of the cylinder before a state is obtained in which the front end side inner peripheral convex portion comes into contact with the annular member and the front end side outer peripheral sealing portion comes into contact with the inner peripheral portion of the cylinder, the base end side inner peripheral convex portion comes into contact with the annular member and the base end side outer peripheral sealing portion comes into contact with the inner peripheral portion of the cylinder.For this reason, the seal ring can be easily inserted between the inner peripheral portion of the cylinder and the outer peripheral portion of the annular member during assembly.In addition, the convex portions are: a front end side outer peripheral convex portion formed on the front end side outer peripheral sealing portion; and a base end side outer peripheral convex portion formed on the base end side outer peripheral sealing portion. The convex portions come into contact with the inner peripheral portion of the cylinder such that the front end side inner peripheral abutting portion and the base end side inner peripheral abutting portion are pushed inward in the radial direction. For this reason, an adhesion degree of the front end side inner peripheral abutting portion and the base end side inner peripheral abutting portion to the outer peripheral portion of the annular member can be increased. Consequently, sealing on the outer peripheral portion side of the annular member can be improved.In addition, the sealing ring is formed integrally with the closure region. For this reason, the sealing ring can be mounted simultaneously with the closure region. Consequently, assembly becomes easier.Further, an outer diameter of the seal ring is larger than an inner diameter of the inner peripheral portion of the cylinder. Consequently, since the degree of adhesion of the seal ring to the inner peripheral portion of the cylinder can be improved, the sealing on the inner peripheral portion side of the cylinder can be improved.In addition, a contact surface of the annular member with the seal ring is an inclined surface. Consequently, when the seal ring is inserted between the outer peripheral portion of the annular member and the inner peripheral portion of the cylinder, a structure in which the base-end-side inner peripheral convex portion comes into contact with the annular member before the front-end-side inner peripheral convex portion comes into contact with the annular member can be easily realized.Further, the front end side outer peripheral sealing portion and the front end side inner peripheral abutting portion, and the base end side outer peripheral sealing portion and the base end side inner peripheral abutting portion overlap each other at positions in the axial direction.According to the above-described embodiment, the sealing member comes into contact with the inner peripheral annular portion and the annular member formed in the inner peripheral portion so as to seal the inner peripheral portion. The seal member is constituted by an annular seal portion disposed coaxially with the annular member, and an annular seal ring integrally formed with the outer circumferential side of the seal portion so as to come into contact with the inner circumferential portion. The seal ring includes a front end side outer peripheral sealing portion formed on the outer peripheral side so as to come into contact with the inner peripheral portion, a base end side outer peripheral sealing portion formed on the outer peripheral side closer to the closing portion than the front end side outer peripheral sealing portion so as to come into contact with the inner peripheral portion, a front end side inner peripheral convex portion protruding on the inner peripheral side so as to come into contact with the outer peripheral portion of the annular member so as to press the front end side outer peripheral sealing portion outward in the radial direction, and a base end side inner peripheral convex portion protruding on the inner peripheral side closer to the closing portion than the front end side inner peripheral convex portion so as to come into contact with the outer peripheral portion of the annular member, the base-end-side outer circumferential sealing portion is pushed outward in the radial direction. Consequently, an assembly property of the seal ring can be improved.Industrial applicabilityAccording to the cylinder device and the sealing member described above, an assembly property of the sealing ring can be improved.10 Cylinder device 11 Cylinder 22 Rod 25 Rod guide (annular member) 26 Sealing member 67 Inner peripheral portion 76 Outer peripheral portion 76 a Außenumfangs outer peripheral surface (contact surface) 88 Closing portion 89 Seal ring 101 First outer peripheral sealing portion 102 Second outer peripheral sealing portion 103 Third outer peripheral sealing portion 104 First inner peripheral abutting portion 105 Second inner peripheral abutting portion 106 Third inner peripheral abutting portion 111 First outer peripheral convex portion (convex portion) 112 Second outer peripheral convex portion (convex portion) 113 Third outer peripheral convex portion (convex portion) 117 First inner peripheral convex portion (convex portion) 118 Second inner peripheral convex portion (convex portion) 119 Third inner peripheral convex portion (convex portion)

Claims

A cylinder device (10) comprising: a cylinder (11) in which a working fluid is sealed; a rod (22) protruding from at least one end of the cylinder (11); a rod guide (25) formed on one end side of the cylinder (11); an annular closing portion (88) formed more outward than the rod guide (25) in an on / off direction of the cylinder (11) so as to close the one end side of the cylinder (11); and an annular seal ring (89) disposed in the direction of the cylinder (11) in the direction of the clean / clean from an outer peripheral side of the closing portion (88) to come into contact with an outer peripheral portion of the rod guide (25) and an inner peripheral portion of the cylinder (11), the seal ring (89) comprising: a front end side outer peripheral sealing portion (101, 102) formed on an outer peripheral side to come into contact with the inner peripheral portion of the cylinder (11); a base end side outer peripheral sealing portion (102, 103) formed on the outer peripheral side closer to the closing portion (88) than the front end side outer peripheral sealing portion (101, 102) to come into contact with the inner peripheral portion of the cylinder (11); a front end side inner peripheral abutting portion (104, 105) formed on the inner peripheral side so as to come into contact with the outer peripheral portion of the rod guide (25); and a base end side inner peripheral abutting portion (105, 106) formed on the inner peripheral side closer to the closing portion (88) than the front end side inner peripheral abutting portion (104, 105) so as to come into contact with the outer peripheral portion of the rod guide (25), wherein the front end side inner peripheral abutting portion (104, 105) and the base end side inner peripheral abutting portion (105, 106) are formed by convex portions protruding in a radial direction, the convex portions are a front end side inner peripheral convex portion (117, 118) formed on the front end side inner peripheral abutting portion (104, 105), and a base-end-side inner peripheral convex portion (118, 119) formed on the base-end-side inner peripheral abutting portion (105, 106), and the convex portions come into contact with the outer peripheral portion of the rod guide (25) such that the front-end-side outer peripheral sealing portion (101, 102) and the base-end-side outer peripheral sealing portion (102, 103) are pushed outward in the radial direction.The cylinder device (10) according to claim 1, wherein shapes of the seal ring (89) are formed such that when the seal ring (89) is inserted between the outer peripheral portion of the rod guide (25) and the inner peripheral portion of the cylinder (11), the base-end-side inner peripheral convex portion (118, 119) comes into contact with the rod guide (25) before the front-end-side inner peripheral convex portion (117, 118) comes into contact with the rod guide (25).The cylinder device (10) according to claim 1 or 2, wherein shapes of the seal ring (89) are formed such that when the seal ring (89) is inserted between the outer peripheral portion of the rod guide (25) and the inner peripheral portion of the cylinder (11), the base-end-side inner peripheral convex portion (118, 119) comes into contact with the rod guide (25) and the base-end-side outer peripheral sealing portion (102, 103) comes into contact with the inner peripheral portion of the cylinder (11) before a state is adopted in which the front-end-side inner peripheral convex portion (118, 119) comes into contact with the rod guide (25) and the front-end-side outer peripheral sealing portion (101, 102) comes into contact with the inner peripheral portion of the cylinder (11).The cylinder device (10) according to any one of claims 1-3, further comprising a front end side outer peripheral convex portion formed on the front end side outer peripheral sealing portion (101, 102) and a base end side outer peripheral convex portion formed on the base end side outer peripheral sealing portion (102, 103), which come into contact with the inner peripheral portion of the cylinder (11) such that the front end side inner peripheral abutting portion (104, 105) and the base end side inner peripheral abutting portion (105, 106) are pushed inward in the radial direction.Cylinder device (10) according to one of Claims 1-4, in which the sealing ring (89) is formed integrally with the closure region (88).The cylinder device (10) according to any one of claims 1-5, wherein an outer diameter of the seal ring (89) is larger than an inner diameter of the inner peripheral portion of the cylinder (11).The cylinder device (10) according to any one of claims 1-6, wherein a contact surface of the rod guide (25) with the seal ring (89) is an inclined surface.The cylinder device (10) according to any one of claims 1-7, wherein the front end side outer peripheral sealing portion (101, 102) and the front end side inner peripheral abutting portion (104, 105), and the base end side outer peripheral sealing portion (102, 103) and the base end side inner peripheral abutting portion (105, 106) overlap each other at positions in an axial direction.A sealing member (26) configured to contact an inner peripheral annular portion and a rod guide (25) formed in an inner peripheral portion to seal the inner peripheral portion, the sealing member (26) comprising: an annular seal portion (88) configured to be coaxially arranged with the rod guide (25); and an annular seal ring (89) integrally formed with an outer peripheral side of the seal portion (88) to contact the inner peripheral portion, the seal ring (89) comprising: a front end side outer peripheral seal portion (101, 102) formed on the outer peripheral side to contact the inner peripheral portion; a base end side outer peripheral sealing portion (102, 103) formed on the outer peripheral side closer to the closing portion (88) than the front end side outer peripheral sealing portion (101, 102) so as to come into contact with the inner peripheral portion; a front end side inner peripheral convex portion (117, 118) protruding on an inner peripheral side so as to come into contact with an outer peripheral portion of the rod guide (25) so as to press the front end side outer peripheral sealing portion (101, 102) outward in a radial direction; and a base-end-side inner-periphery convex portion (118, 119) disposed closer to the shutter portion (88) than the front-end-side inner-periphery convex portion (117, 118) and protruding on the inner periphery side so as to come into contact with the outer peripheral portion of the rod guide (25) so as to press the base-end-side outer-periphery sealing portion (102, 103) outward in the radial direction.

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