shock absorber

Abstract

Shock absorbers (11, 11A), comprising: a cylinder (12) filled with a working fluid, an outer tube (14) which is provided on an outer circumferential side of the cylinder (12), a reservoir chamber (13) which is formed between the outer tube (14) and the cylinder (12), a piston (18) which comes into sliding contact with a surface side of the cylinder (12) and divides the inside of this cylinder (12) into a one-side chamber (16) and an opposite-side chamber (17), a piston rod (15) to which the piston (18) is fixed at one end and an opposite end extends from the cylinder (12), a sealing component (21) that comes into sliding contact with the piston rod (15) and prevents the working fluid from leaking out of the cylinder (12), a rod guide (20) which is provided at a position on a side defined by the sealing component (21) of the cylinder (12) and guides the piston rod (15), a friction generating component (22, 22A) which is provided at a position on a side defined by the sealing component (21) of the cylinder (12) and comes into sliding contact with the piston rod (15), an oil storage chamber (85A) which is connected to the reservoir chamber (13), an inner chamber (261) which is connected to the oil storage chamber (85A) and the reservoir chamber (13), and a chamber (151A) which is connected to the inner chamber (261), wherein the friction generating component (22, 22A) has an annular elastic rubber area (91, 91A) which comes into contact with the piston rod (15), and a base area (92, 92A) to which this elastic rubber area (91, 91A) is firmly attached, characterized by the fact that the elastic rubber area (91, 91A) is formed such that the elastic rubber area (91, 91A) is located away from an outer circumferential surface of the piston rod (15) and that an upstream side and a downstream side of the elastic rubber area (91, 91A) are able to communicate with each other when a differential pressure between the single-sided chamber (16), the chamber (151A) of the cylinder (12), the inner chamber (261), the oil storage chamber (85A) and the reservoir chamber (13) decreases and the differential pressure reaches a predetermined pressure, wherein a cross-sectional area of ​​a communication path (152, 252) formed in the base region (92, 92A) is smaller than a cross-sectional area of ​​a communication path (64) between the piston rod (15) and the rod guide (20), and wherein the upstream side and the downstream side communicate with each other via the communication path (64) between the piston rod (15) and the rod guide (20), and the communication path (152, 252) formed in the base area (92, 92A).

Description

Technical field

[0001] The present invention relates to a shock absorber. State of the art

[0002] A shock absorber comprising a friction generating component which provides frictional resistance with respect to a moving piston rod, in addition to a sealing component which prevents leakage of a working fluid, has been disclosed (see, for example, patent document 1). (List of citations) (Patent document)

[0003] Patent document 1: JP 4 312 973 B2

[0004] DE 10 2014 203 076 A1 discloses features that fall under the preamble of claim 1. WO 2020 / 044 973 A1 is prior art that is only relevant for the novelty requirement to the extent that it effectively claims the priority of Japanese patent application JP 2018 - 159 983 A. Summary of the invention: Technical problem

[0005] With regard to shock absorbers, it is desirable to obtain favorable operating characteristics using a friction-generating component.

[0006] Therefore, it is an object of the present invention to provide a shock absorber capable of maintaining favorable working characteristics. Problem solving

[0007] The invention is defined by claim 1.

[0008] According to one aspect of the present invention, a shock absorber is provided which includes a friction-generating component located at a position on a side defined by a sealing component of a cylinder and which comes into sliding contact with a piston rod. The friction-generating component has an annular elastic rubber region that comes into sliding contact with the piston rod and a base region to which this elastic rubber region is fixedly attached. The elastic rubber region is configured such that an upstream side and a downstream side of the elastic rubber region are able to communicate with each other when a differential pressure between a side chamber of the cylinder and a reservoir chamber reaches a predetermined pressure. Advantageous effects of the invention

[0009] According to the above shock absorber, it is possible to obtain favorable working characteristics. Brief description of drawings Fig. Figure 1 is a cross-sectional view illustrating a shock absorber according to a first embodiment of the present invention. Fig. Figure 2 is a partial cross-sectional view illustrating a piston rod extension side of the shock absorber according to the first embodiment of the present invention. Fig. Figure 3 is a single-sided cross-sectional view illustrating a main part of the shock absorber according to the first embodiment of the present invention. Fig. Figure 4 is a partial cross-sectional view illustrating a piston rod extension side of a shock absorber according to a second embodiment of the present invention. Fig. Figure 5 is a one-sided cross-sectional view illustrating a main part of the shock absorber according to the second embodiment of the present invention. Description of embodiments (First embodiment)

[0010] A shock absorber according to a first embodiment of the present invention is described below with reference to Fig. 1, Fig. 2 to Fig. 3 described.

[0011] A shock absorber 11 according to the first embodiment is a fluid pressure shock absorber in which a working fluid is used. More specifically, the shock absorber 11 is a hydraulic shock absorber in which a hydraulic fluid is used as a working fluid. The shock absorber 11 is used in a suspension device of an automobile.

[0012] The shock absorber 11 has a cylinder 12 with a cylindrical shape filled with a working fluid, an outer tube 14 having a larger diameter than the cylinder 12 and a cylindrical shape with a bottom provided on an outer circumferential side of the cylinder 12 in a state to be coaxial with the cylinder 12, and a reservoir chamber 13 formed between the outer tube 14 and the cylinder 12.

[0013] Additionally, the shock absorber 11 has a piston rod 15 arranged on a central axis line of the cylinder 12, wherein one end region is arranged in an axial direction inside the cylinder 12, and wherein an opposite end region extends in the axial direction to the outside from the cylinder 12 and the outer tube 14; and a piston 18, which is fixed at an end region of this piston rod 15 in the axial direction, comes into sliding contact with an inner surface of the cylinder 12, and divides the interior of the cylinder 12 into two chambers, such as a one-sided chamber 16 and an opposite-sided chamber 17.

[0014] The piston rod 15 moves integrally with the piston 18, which is connected to one end of the rod. The opposite end of the piston rod 15 projects to the outside of the cylinder 12 and the outer tube 14. A hydraulic fluid, serving as the working fluid, is sealed inside the cylinder 12. A hydraulic fluid, serving as the working fluid, and a high-pressure gas are enclosed in the reservoir chamber 13 between the cylinder 12 and the outer tube 14. Instead of a high-pressure gas, air at atmospheric pressure may be enclosed within the reservoir chamber 13. For example, in the shock absorber 11, the outer tube 14 is coupled to a wheel side of a vehicle, and the piston rod 15 is coupled to the vehicle body, thus buffering vibration from the wheels to the vehicle body.

[0015] With regard to the position of an end region of each cylinder 12 and the outer tube 14 on a side where the piston rod 15 projects, the outer tube 14 is on an outward side (one side of it in upward / downward direction in Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5) in an inward / outward direction (upward / downward direction in Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5, which is subsequently shown as a cylinder inward / outward direction) in the axial direction of the cylinder 12 and the outer tube 14 from the cylinder 12. The shock absorber 11 has a rod guide 20 which is mounted on parts of the cylinder 12 and the outer tube 14 on an outward side in the cylinder inward / outward direction, and a sealing element 21 which is arranged on an outward side in the cylinder inward / outward direction from the rod guide 20 and is attached to a part of the outer tube 14 on an outward side in the cylinder inward / outward direction.

[0016] Additionally, the shock absorber 11 has a friction generating component 22, which extends on an inward side in the cylinder inward / outward direction from the sealing component 21 (one side below in the upward / downward direction). Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5) and is provided between the sealing component 21 and the rod guide 20, and a base valve 23, which is arranged at an end region on one side opposite to the rod guide 20 in the axial direction of the cylinder 12 and the outer tube 14, the sealing component 21 and the friction generating component 22.

[0017] All components of the rod guide 20, the sealing component 21, and the friction-generating component 22 have an annular shape. The piston rod 15 is inserted through the inner surface of each of the rod guide 20, the sealing component 21, and the friction-generating component 22 in such a way that it can slide. The rod guide 20 restricts the movement of the piston rod 15 in a radial direction, holds the piston rod 15 so that it can move in the axial direction, and guides the piston rod 15 so that it moves only in the axial direction.

[0018] The sealing element 21 comes into sliding contact with an outer circumferential region of the piston rod 15, which moves axially around an inner circumferential region of the sealing element 21. This prevents hydraulic fluid inside the cylinder 12 and high-pressure gas and hydraulic fluid inside the reservoir chamber 13 from leaking out of the cylinder 12 and the outer tube 14. In other words, the sealing element 21 prevents hydraulic fluid and gas inside the cylinder 12 and the outer tube 14 from leaking outside the shock absorber 11. The rod guide 20 is located in the cylinder 12 on one side, which is defined by the sealing element 21, and guides the piston rod 15.

[0019] In the friction-generating component 22, an outer circumferential region is fixed by being mounted on the rod guide 20. The friction-generating component 22 comes into sliding contact with the outer circumferential region of the piston rod 15 at an inner circumferential region and generates frictional resistance in the piston rod 15, but is not intended for sealing. The friction-generating component 22 is positioned in the cylinder 12 on a side defined by the sealing component 21 and comes into sliding contact with the piston rod 15.

[0020] The outer tube 14 has a substantially cylindrical shape with a base, comprising a main part 25 with a cylindrical shape and a base part 26, which closes an end face opposite a projecting side of the piston rod 15 in this main part 25. The main part 25 has a locking area 28 that projects inwards in a radial direction from a position of an opening area 27 on the projecting side of the piston rod 15.

[0021] The cylinder 12 has a cylindrical shape. In the assembled state, one end of the cylinder 12 is held axially by a base body 30 of the base valve 23, which is subject to positioning, and is located on the inner side of the bottom part 26 of the outer tube 14. An opposite end of the cylinder 12, also axially, is held in the assembled state by the rod guide 20, which is subject to positioning, and is mounted in the side of the opening area 27 of the outer tube 14.

[0022] Oil passages 31 and 32, which allow communication between the opposite side chamber 17 inside the cylinder 12 and the reservoir chamber 13 between the outer tube 14 and the cylinder 12, are formed in the base body 30 of the base valve 23. Additionally, a poppet valve 33, which serves as a contraction-side damping valve capable of opening and closing the oil passage 31 on the inner side, is provided in the base body 30 on the side of the bottom part 26 in the axial direction. A poppet valve 34, which serves as a check valve capable of opening and closing the oil passage 32 on the outer side, is arranged on one side opposite the bottom part 26 in the axial direction. These poppet valves 33 and 34 are attached to the base body 30 using a rivet 35, which is inserted through the base body 30.In the present embodiment, the disc valves 33 and 34 are designed to be attached to the base body 30 using the rivet 35 which is inserted through the base body 30, but they can be attached using a bolt and nut.

[0023] The poppet valve 33 allows a flow of hydraulic fluid from the opposite side chamber 17 to the side of the reservoir chamber 13 via a (not illustrated) passage hole of the poppet valve 34 and the oil passage 31, generating a damping force while restricting the flow of hydraulic fluid in the opposite direction. In contrast, the poppet valve 34 allows a flow of hydraulic fluid from the reservoir chamber 13 to the side of the opposite side chamber 17 via the oil passage 32 without any resistance, while restricting the flow of hydraulic fluid in the opposite direction.The poppet valve 33 is a damping valve that generates a damping force when the oil passage 31 is opened. This occurs when the piston rod 15 moves towards a contraction side, increasing the amount of oil entering the cylinder 12 and the outer tube 14. The piston 18 then moves towards the opposite side chamber 17, and the pressure in the opposite side chamber 17 becomes higher than the pressure in the reservoir chamber 13. Additionally, the poppet valve 34 opens the oil passage 32 when the piston rod 15 moves towards an expansion side. This increases the amount of oil entering the cylinder 12 and the outer tube 14. The piston 18 then moves towards the side of the single-sided chamber 16, and the pressure in the opposite side chamber 17 falls below the pressure in the reservoir chamber 13. The disc valve 34 is a suction valve that causes a hydraulic fluid to flow from the reservoir chamber 13 at that time practically without generating a damping force within the opposite side chamber 17.

[0024] A damping force on the extension side can be actively generated by the disc valve 34, which acts as a check valve. Additionally, these pin-insertion disc valves 33 and 34 can be eliminated, and openings can be used.

[0025] The piston rod 15 has a main shaft section 38, which has an outer circumferential surface 37 consisting of a cylindrical surface with a uniform diameter and an inner end shaft section 39, which has a smaller diameter than the main shaft section 38 and is located at an end on one side that is inserted into the cylinder 12. A nut 40 is screwed onto this inner end shaft section 39, and the piston 18 and poppet valves 41 and 42 on both sides of it are attached to the inner end shaft section 39 by the nut 40.

[0026] The single-sided chamber 16 is formed between the piston 18 and the rod guide 20. The single-sided chamber 16 is a rod-side chamber in which the piston rod 15 penetrates the inner surface. The opposite-side chamber 17 is formed between the piston 18 and the base valve 23. The opposite-side chamber 17 is a bottom-side chamber on the side of the bottom part 26 in the cylinder 12. The piston rod 15 does not penetrate the inner surface of the opposite-side chamber 17.

[0027] The piston rod 15 incorporates a stop component 47 and a buffer body 48, both torus-shaped, located on a portion of the main shaft section 38 between the piston 18 and the rod guide 20. The piston rod 15 is inserted through an inner circumferential face of the stop component 47. The stop component 47 is caulked and fixed to the main shaft section 38. The piston rod 15 is inserted through the inner face of the buffer body 48. The buffer body 48 is positioned between the stop component 47 and the rod guide 20. The buffer body 48 abuts the rod guide 20 and dampens shock as the piston rod 15 extends to its end.

[0028] Oil passages 40 and 45, which allow communication between the opposite-side chamber 17 in the cylinder 12 on the side of the bottom part 26 in the axial direction and the single-side chamber 16 on one side opposite the bottom part 26, are formed in the piston 18. Additionally, the poppet valve 41, which serves as a contraction-side damping valve capable of opening and closing the oil passage 44, is arranged in the piston 18 on one side opposite the bottom part 26 in the axial direction. The poppet valve 42, which serves as an expansion-side damping valve capable of opening and closing the oil passage 45, is arranged in the piston 18 on the side of the bottom part 26 in the axial direction.

[0029] The poppet valve 41 allows a flow of hydraulic fluid from the opposite side chamber 17 to the side of the single-sided chamber 16 via the oil passage 44, while a flow of hydraulic fluid in the opposite direction is restricted. In contrast, the poppet valve 42 allows a flow of hydraulic fluid from the side of the single-sided chamber 16 to the opposite side chamber 17 via the oil passage 45, while a flow of hydraulic fluid in the opposite direction is restricted. A (not illustrated) locking orifice, which allows communication between the opposite side chamber 17 and the single-sided chamber 16 via the oil passage 44, even when the poppet valve 41 is in a closed state, is provided between the poppet valve 41 and the piston 18.A locking opening (not illustrated), which allows communication between the opposite side chamber 17 and the single side chamber 16 via the oil passage 45, even if the poppet valve 42 is in a closed state, is also provided between the poppet valve 42 and the piston 18.

[0030] If the piston rod 15 moves towards the contraction side, the piston 18 moves towards the opposite side chamber 17. If the pressure in the opposite side chamber 17 becomes higher than that in the single-side chamber 16, a locking orifice (not illustrated) causes hydraulic fluid to flow from the opposite side chamber 17 to the single-side chamber 16 in a uniform flow channel area in a region where the piston 18's movement speed (hereinafter referred to as a piston speed) is low. Accordingly, a damping force with opening characteristics is generated. Additionally, in a region of high piston speed, the poppet valve 41 is separated from the piston 18, opens the oil passage 44, and causes hydraulic fluid to flow from the opposite side chamber 17 to the single-side chamber 16 in a flow channel area corresponding to the separation volume from the piston 18. Accordingly, a damping force with a valve characteristic is generated.

[0031] If the piston rod 15 moves towards the expansion side, the piston 18 moves towards the side of the single-sided chamber 16. If the pressure in the single-sided chamber 16 becomes higher than that in the opposite-sided chamber 17, a (not illustrated) locking orifice causes hydraulic fluid to flow from the single-sided chamber 16 to the opposite-sided chamber 17 in a uniform flow channel area in a region of low piston velocity. A damping force with opening characteristics is thus generated. Additionally, in a region of high piston velocity, the poppet valve 42 is separated from the piston 18, the oil passage 45 opens, and hydraulic fluid flows from the single-sided chamber 16 to the opposite-sided chamber 17 in a flow channel area corresponding to a separation distance from the piston 18. A damping force with valve characteristics is thus generated.

[0032] If the piston rod 15 moves towards the expansion side and the amount of fluid discharged from the cylinder 12 and the outer tube 14 increases, a hydraulic fluid corresponding to this amount opens the poppet valve 34 of the base valve 23 and flows from the reservoir chamber 13 to the opposite side chamber 17 via the oil passage 32. Conversely, if the piston rod 15 moves towards the contraction side and the amount of fluid discharged into the cylinder 12 and the outer tube 14 increases, a hydraulic fluid corresponding to this amount opens the poppet valve 33 and flows from the opposite side chamber 17 via the oil passage 31 to the reservoir chamber 13.

[0033] As in Fig. As illustrated in Figure 2, the rod guide 20 has a metal rod guide main body 49, which has a substantially stepped cylindrical shape. Within the rod guide main body 49, a large outer diameter region 50 is formed on one side in the axial direction, and a small outer diameter region 51 with a smaller diameter than the large outer diameter region 50 is formed on the opposite side in the axial direction. The rod guide main body 49 has an external shape in which an intermediate outer diameter region 52 is formed with an intermediate outer diameter between it. The rod guide main body 49 is mounted in the inner circumferential region of the cylinder 25 of the outer tube 14 in the large outer diameter region 50 and in the inner circumferential region of the cylinder 12 in the small outer diameter region 51.

[0034] In the radial direction of the main rod guide body 49, a large-diameter hole region 53 with a circular shape is formed at one end on the side of the large outer diameter region 50 in the axial direction. In the radial direction of the main rod guide body 49, a large-diameter hole region 54 with a circular shape and a smaller diameter than the large-diameter hole region 53 is formed on the side of the small outer diameter region 51, axially extending from the large-diameter hole region 53. Additionally, a conical hole region 55, which has a smaller diameter when separated from the large-diameter hole region 54, is formed on one side of the large-diameter hole region 54, opposite to the large-diameter hole region 53 in the axial direction.An intermediate diameter hole area 56 with a circular shape and a slightly smaller diameter than the large diameter hole area 54 is formed on one side of the conical hole area 55, axially opposite to the large diameter hole area 54. Additionally, a small diameter hole area 57 with a different shape and a smaller minimum diameter than the conical hole area 55 is formed on one side of the intermediate diameter hole area 56, axially opposite to the intermediate diameter hole area 56. A smallest diameter hole area 58, with a smaller diameter than the smallest diameter of the small diameter hole area 57, is formed on one side of the small diameter hole area 57, axially opposite to the intermediate diameter hole area 56.

[0035] As in Fig. Figure 3 illustrates recessed areas 60, which extend radially outwards from a minimum inner diameter area 59 with the smallest inner diameter in the small-diameter hole area 57, and which have a different shape within the small-diameter hole area 57. The recessed areas 60 extend radially outwards to locations in the vicinity of an inner circumferential surface of the intermediate-diameter hole area 56. A plurality of recessed areas 60 are formed at intervals in a circumferential direction of the small-diameter hole area 57.

[0036] As in Fig. As illustrated in Figure 2, an annular projection 61 with a toric shape is formed at an end region of the rod guide main body 49 on the side of the large outer diameter region 50, projecting outwards in the axial direction. The largest diameter hole region 53 is formed on the inside of this annular projection 61. A communication hole 62 penetrating through the rod guide main body 49 is formed in the axial direction on the inner diameter side of the annular projection 61. In the communication hole 62, one end opens within the largest diameter hole region 53, and the opposite end opens on a surface on the side of the intermediate outer diameter region 52 of the large outer diameter region 50. The communication hole 62 communicates with the reservoir chamber 13 between the outer tube 14 and the cylinder 12.

[0037] The rod guide 20 consists of the main rod guide body 49 and a cylindrical collar 63, which is mounted and fixed to the inner circumferential region of the main rod guide body 49. The collar 63 is formed by coating the inner circumference of a metal cylinder, such as an SPCC or SPCE material, with a fluoropolymer-integrated bronze. The collar 63 is press-fitted into the small-diameter hole region 58 of the main rod guide body 49. The piston rod 15 is inserted into the rod guide 20 through the interior of this collar 63 so that it comes into sliding contact with the outer circumferential surface 37 of the main shaft region 38. Due to the press-fit, there is no gap between the main rod guide body 49 and the collar 63, and the rod guide 20 is not penetrated axially. In contrast, these can slide between the collar 63 and the piston rod 15.Accordingly, it serves as a communication path 64, which penetrates the rod guide 20 to a small degree in the axial direction.

[0038] The sealing element 21 is arranged axially at an end region of the outer tube 14 and comes into pressure contact with the outer circumferential surface 37 of the electric motor 38 of the piston rod 15 in its inner circumferential region. The sealing element 21 restricts leakage to the outside, such as hydraulic fluid leaking from a gap between the rod guide 20 and the main shaft region 38 of the piston rod 15. Fig. Figure 2 illustrates the side of the rod guide 20 of the shock absorber 11 in a state where the piston rod 15 is excluded. Thus, the sealing component 21 is in its natural state before the piston rod 15 is inserted through it. Furthermore, the outer circumferential surface 37 of the main shaft area 38 of the piston rod 15, when inserted through it, is indicated by an imaginary line (two-dot dashed line).

[0039] The sealing component 21 consists of an oil seal main body 67 (integrated component) comprising a sealing area 65, which is formed from an elastic rubber material (such as nitrile rubber or a fluororubber with favorable sliding properties), and an annular metal component 66, which has a toric shape embedded within the sealing area 65, which maintains the shape of the sealing component 21 and provides strength for fixing; a ring spring 68, which is mounted on an outer circumferential region of the sealing area 65 of the oil seal main body 67 on an outside in the cylinder-inward / outward direction; and a ring spring 69, which is mounted on the outer circumferential region of the sealing area 65 on an inward side in the cylinder-inward / outward direction.

[0040] A part of the sealing area 65 on an inward side in the radial direction has a dust lip 72 with a torus tube shape, which extends in a direction in which it is separated from the annular component 66 in the axial direction, from an outer side in the cylinder inward / outward direction on the inner circumferential side of the annular component 66, and an oil lip 73 with a torus tube shape, which extends in a direction in which it is separated from the annular component 66 in the axial direction from an inward side in the cylinder inward / outward direction on the inner circumferential side of the annular component 66.Additionally, part of the sealing area 65 has an outer circumferential seal 74 on an outer side in the radial direction, which covers an outer circumferential surface of the annular component 66 at an outer end position of the same, and a sealing lip 75 with a torus shape, which projects from an outer circumferential seal 74 to an inward side in the cylinder inward / outward direction.

[0041] The dust lip 72 has an overall conical, tubular shape, exhibiting a smaller inner diameter when separated from the annular component 66 at an outer end in the cylinder's inward / outward direction. An annular groove 78 for fitting the protruding spring 68 is formed in the outer circumferential region of the dust lip 72 such that it is recessed inwards in the radial direction. An example utilizing the spring 68 has been described in the present embodiment, but this is not essential.

[0042] The oil lip 73 has a conical tubular shape overall, with a smaller diameter at the point where it separates from the annular component 66 to an inward side in the cylinder's inward / outward direction. An annular groove 79 for fitting the protruding spring 69 is formed in the outer circumferential region of the oil lip 73 such that it is recessed in the radial direction.

[0043] The sealing component 21 comes into sealing contact with the inner circumferential region of the main part 25 of the outer tube 14 in the outer circumferential seal 74 in a state in which the dust lip 72 is arranged on an atmospheric side, i.e., on an outer side in the cylinder's inward / outward direction, and the oil lip 73 is arranged on an inward side in the cylinder's inward / outward direction. In this state, the position of the annular component 66 between the annular projection 61 of the rod guide 20 and the caulked locking area 28 of the outer tube 14 is sandwiched and locked. At this time, the sealing lip 75 in the sealing component 21 is arranged between the annular projection 61 of the rod guide 20 and the outer tube 14 and thus comes into sealing contact. Additionally, the oil lip 73 is arranged within the large diameter hole area 54 of the rod guide 20 with a gap in between in the radial direction.

[0044] The main shaft section 38 of the piston rod 15 is inserted through the inside of the dust lip 72 and the oil lip 73 in the sealing component 21 in a state in which it is attached to the outer tube 14.

[0045] In this state, one end of the piston rod 15 protrudes from one end of the cylinder 12 and the outer tube 14, the dust lip 72 is provided on an end side where the piston rod 15 protrudes from the outer tube 14, and the oil lip 73 is provided on an inward side in the cylinder inward / outward direction from the dust lip 72.

[0046] The spring 68, which is mounted in the annular groove 78 of the dust lip 72, maintains a holding force in a constant state in one direction of adhesion of the piston rod 15 of the dust lip 72. Additionally, the spring 68 is also used to adjust a bending strength to meet a design specification. The spring 69, which is mounted in the annular groove 79 of the oil lip 73, adjusts a holding force in the direction of adhesion of the piston rod 15 of the oil lip 73.

[0047] In the aforementioned sealing component 21, the dust lip 72 adheres to the piston rod 15 and maintains airtightness due to the interaction of the dust lip and the binding force of the spring 68. In the sealing component 21, the dust lip 72 primarily restricts the access of foreign materials adhering to the piston rod 15 when it is exposed to the outside. Additionally, the oil lip 73 also adheres to the piston rod 15 and maintains airtightness due to the interaction of the dust lip and the binding force of the spring 69. The oil lip 73 scrapes off any hydraulic fluid adhering to the piston rod 15 as it extends, thus restricting leakage to its outer surface. The oil lip 73 primarily stores hydraulic fluid in a chamber 85 (low-pressure chamber) formed by the large-diameter hole area 54 on an inward side in the cylinder's inward / outward direction relative to the sealing component 21.In particular, chamber 85 is an oil storage chamber for storing hydraulic fluid. Chamber 85 communicates with reservoir chamber 13 at all times via the communication hole 62 of the rod guide 20. The pressure in chamber 85 is the same as that in reservoir chamber 13.

[0048] The friction-generating component 22 is press-fitted into the intermediate diameter hole area 56 of the rod guide main body 49. At this time, the friction-generating component 22 abuts a bottom area of ​​the intermediate diameter hole area 56. The friction-generating component 22 is located on an inward side in the cylinder inward / outward direction from the sealing component 21, that is, on an inner side of the cylinder 12 and the outer tube 14. The friction-generating component 22 comes into pressure contact with the outer circumferential surface 37 of the main shaft area 38 of the piston rod 15 in its inner circumferential area. Thus, the friction-generating component 22 generates pressure resistance against the piston rod 15. Fig. 2 and Fig. Figure 3 illustrates states in which the piston rod 15 is excluded and the friction-generating component 22 is also in its natural state before the piston rod 15 is inserted through it. Furthermore, the outer circumferential surface 37 of the main shaft region 38 of the piston rod 15, in the case of insertion, is indicated by an imaginary line (two-dotted line).

[0049] As in Fig. As illustrated in Figure 2, the friction-generating component 22 is an integrated component consisting of an annular elastic rubber section 91, made of an elastic rubber material such as nitrile rubber or fluorocarbon rubber, and an annular metal base section 92 to which the elastic rubber section 91 is rigidly attached. The friction-generating component 22 is mounted in the intermediate diameter hole region 56 of the rod guide 20 in the base section 92. The friction-generating component 22 comes into sliding contact with the outer circumferential surface 37 of the main shaft region 38 of the piston rod 15 in the elastic rubber section 91. The base section 92 maintains the shape of the elastic rubber section 91 and provides rigidity for fixing the rod guide 20.

[0050] With reference to Fig. 3 describes the friction-generating component 22 in its natural state. As shown in the single-sided cross-section of Fig. Figure 3 illustrates that in the friction-generating component 22, the base region 92 has a cylindrical shape with a base, consisting of an annular disk region 101 with a perforated flat disk plate shape and an annular fixing region 102 extending from the outer circumferential side of the annular disk region 101 to one side in the axial direction. The fixing region 102 extends in the axial direction, having the side of the annular disk region 101 as its base end, and is formed in a state where it is coaxial with the annular disk region 101. The fixing area 102 extends only on one side in the axial direction from the outer circumferential side of the annular disk area 101. The central axes of the annular disk area 101 and the fixing area 102 coincide with each other and the fixing area 102 extends such that it is perpendicular to the annular disk area 101.For example, in the base area 92, the fixing area 102 is formed on a flat, plate-shaped material by plastic deformation, or the annular disc area 101 is formed from a cylindrical material by plastic deformation.

[0051] The annular disk area 101 has an inner base surface 103, which consists of a circular flat surface on the side of the fixing area 102 in the axial direction, an inner circumferential surface 104 composed of a cylindrical surface on one side opposite the fixing area 102 in the radial direction, and an outer base surface 105 composed of a circular flat surface on one side opposite the fixing area 102 in the axial direction. The inner circumferential end region of the inner base surface 103 is connected to one end region on the inner circumferential surface 104 in the axial direction. The inner circumferential end region on the outer base surface 105 is connected to the opposite end region on the inner circumferential surface 104 in the axial direction.

[0052] The fixing area 102 has an inner circumferential surface 106, which consists of a cylindrical surface on the annular disc area 101 side in the radial direction; a distal end surface 107, which consists of a circular flat surface on one side opposite the annular disc area in the axial direction; and an outer circumferential surface 108, which consists of a cylindrical surface on one side opposite the annular disc area 101 in the radial direction. The end region on the inner circumferential surface 106, on one side opposite the annular disc area 103 in the axial direction, is connected to the inner diameter region on the distal end surface 107. The end region on the outer circumferential surface 108, on one side opposite the annular disc area 101 in the axial direction, is connected to the outer diameter region on the distal end surface 107.The annular disk area 101 has an inner side rounding chamfer 109, which has a toric shape on one side where the inner bottom surface 103 and the inner circumferential surface 106 are close together, and also has an outer side rounding chamfer 110 with a toric shape on one side where the outer bottom surface 105 and the outer circumferential surface 108 are close together.

[0053] In the base region 92, the center axes of the inner bottom surface 103, the inner circumferential surface 104, the outer bottom surface 105, the inner circumferential surface 106, the distal end surface 107, the outer circumferential surface 108, the inner chamfer 109, and the outer chamfer 110 coincide. The inner bottom surface 103, the outer bottom surface 105, and the distal end surface 107 expand such that they are orthogonal to the center axes. In the base region 92, an inner end with the smallest diameter serves as the inner circumferential surface 104 of the annular disk region 101.

[0054] Penetration holes 111, which penetrate the outer bottom surface 105 from the side of the inner bottom surface 103 of the inner chamfer 109, are formed in the annular disc area 101 of the base area 92. The penetration holes 111 are parallel to the center axis lines in the annular disc area 101 and the fixing area 102, that is, the center axis line of the base area 92 is parallel to the center axis line of the brake caliper 22. A plurality of penetration holes 111 are formed at equal intervals in the circumferential direction of the annular disc area 101.

[0055] The elastic rubber region 91 has a torus shape with a central axis that coincides with that of the base region 92. The elastic rubber region 91 has a main body region 121, which is arranged such that it is separated inwards in the radial direction from the fixing region 102 of the base region 92 and is formed on the side of the fixing region 102 of the annular disc region 101 in the axial direction, and an inner coated region 122, which projects outwards in the axial direction from the end region of the inner circumferential region 121 on the annular disc region 101 and is formed on the inner circumferential side of the annular disc region 101.

[0056] In the main body region 121, an outer circumferential region 127 with an outer circumferential surface 126 is separated inwards in the radial direction from the inner circumferential surface 106 of the fixing region 102 of the base region 92 over its entire surface. The main body region 121 is positioned on an inwards side in the radial direction of the base region 92 from the penetration holes 111 of the annular disk region 101 of the base region 92. The main body region 121 is fixedly attached to the inner bottom surface 103 of the annular disk region 101 of the base region 92 on a base-end fixing attachment surface 128, which is connected to one side of the outer circumferential surface 126 in the axial direction. The outer circumferential surface 126 has a conical shape, which increases in diameter towards the side of the base-end fixing attachment surface 128 in the axial direction. The outer circumferential surface 126 is exposed without being firmly fixed to the base area 92.Thus, the elastic rubber area 91 overlaps the inner circumferential side of the ring-shaped fixing area 102 in the axial direction and is designed so that it is completely separated in the radial direction.

[0057] The inner coated area 122 is fixedly attached to the inner circumferential surface 104 of the annular disc area 101 of the base area 92 on an inner circumferential fixing surface 129, which is connected at one side opposite the outer circumferential surface 126 to a base-end fixing surface 128. In the elastic rubber area 91, a part that comes into contact with the base area 92 is fixedly attached to the base area 92 over its entire surface. The elastic rubber area 91 is fixedly attached only to the annular disc area 101 of the same with respect to the base area 92.

[0058] The elastic rubber area 91 has a distal end area 135 which includes a distal end surface 134 that is exposed without being fixed to the base area 92 in a direction opposite to the base end fixing attachment surface 128 of the flat plate area 121 in the axial direction.

[0059] In the elastic rubber area 91, an inner circumferential area 136 is also exposed at the base area 92 without being firmly attached.The inner circumferential region 136 of the elastic rubber region 91 has a smallest inner diameter region 137, which is the smallest diameter in the elastic rubber region 91 and also the smallest diameter in the friction-generating component 22, wherein a distal end-facing conical region 139, which has a conical inner circumferential surface 138, expands as it increases in diameter when separated from the smallest inner diameter region 137 to the side of the distal end surface 134 in the axial direction from the smallest inner diameter region 137, and a base-facing conical region 141, which has a conical inner circumferential surface 140, expands as it increases in diameter when it is separated from the smallest inner diameter region 137 to a side opposite to the distal end surface 134 in the axial direction from the smallest inner diameter region 137.

[0060] The smallest inner diameter region 137, the distal end conical region 139 and the base end conical region 141 are formed in the main body region 121.

[0061] In the elastic rubber region 91, the inner circumferential region 136 has a uniform diameter region 143, which has a cylindrical inner circumferential surface 142 that is connected on one side opposite to the smallest inner diameter region 137 on the inner circumferential surface 140, and a conical region 145, which has a conical inner circumferential surface 144 that rises on one side opposite to the inner circumferential surface 140 when separated from the inner circumferential surface 142. The inner circumferential surface 144 is connected to the outer bottom surface 105 of the annular disc region 101. The uniform diameter region 143 and the conical region 145 are formed in the inner coated region 122.

[0062] In other words, the elastic rubber region 91 comprises the smallest inner diameter region 137, the distal end conical region 139, and the base end conical region 141 on both sides of the smallest inner diameter region 137 in the axial direction, and the uniform diameter region 143 and the conical region 145 on the inner circumferential side. A boundary section between the distal end conical region 139 and the base end conical region 141 serves as the smallest inner diameter region 137. With respect to the distal end conical region 139 and the base end conical region 141, the distal end conical region 139 is arranged on one side far away from the annular disk region 101 of the base region 92, and a base end conical region 141 is arranged on one side close to the annular disk region 101 in the axial direction of the elastic rubber region 91.In other words, the elastic rubber area 191, the smallest inner diameter area 137, the distal end conical area 139, which expands as its diameter increases in the axial direction from the smallest inner diameter area 137 opposite to the single-sided chamber 16, and the base end conical part 141, which expands as its diameter increases in the axial direction from the smallest inner diameter 137 to the single-sided chamber 16, are provided on the inner circumferential side.

[0063] All of the smallest inner diameter region 137, the distal end conical region 139, the base end conical region 141, the uniform diameter region 143, and the conical region 145 exhibit a torus shape continuously over their entire circumference in the circumferential direction of the elastic rubber region 91. Since the elastic rubber region 91 has a central axis that coincides with that of the base region 92, the outer circumferential surface 126, the distal end surface 134, the inner circumferential surface 138, the smallest inner diameter region 137, the inner circumferential surface 140, the inner circumferential surface 142, and the inner circumferential surface 144 also have a central axis that coincides with that of the base region 92.

[0064] As in Fig. As illustrated in Figure 2, the friction-generating component 22 with the aforementioned structure is mounted and fixed to the intermediate diameter hole area 56 (fixing target part) by pressing it in from the side of the large diameter hole area 54 and the rod guide 20 in a position in which the annular disk area 101 of the base area 92 is positioned on an inward side in the cylinder-inward / outward direction from the fixing area 102. At this time, as shown in Fig. As illustrated in Figure 3, in the friction-generating component 22, the fixing area 102 of the base area 92 is mounted on the inner circumferential surface of the intermediate diameter hole area 56 on the outer circumferential surface 108, and the annular disk area 101 abuts the bottom surface of the bottom area of ​​the intermediate diameter hole area 56 on the outer bottom surface 105. At this time, communication is achieved through the penetration holes 111 by aligning their positions with those of the recessed areas 60 in the circumferential direction of the smallest inner diameter area 59. The base area 92 has an annular fixing area 102 for fixing the friction-generating component 22 to the intermediate diameter hole area 56 of the rod guide 20 (target part).

[0065] In the inner circumferential region 136 of the elastic rubber region 91, the distal end conical region 139 is arranged on an outside side in the cylinder-inward / outward direction from the smallest inner diameter region 137, and the base end conical region 141 is arranged on an inside side in the cylinder-inward / outward direction from the smallest inner diameter region 137.

[0066] In the friction-generating component 22, the inner diameter of the smallest inner diameter region 137 is smaller than the outer diameter of the main shaft region 38 of the piston rod 15, i.e., the diameter of the outer circumferential surface 37. Thus, the main shaft region 38 of the piston rod 15 is introduced by the friction-generating component 22 with a predetermined interference on the inside of the elastic rubber region 91. As a result, in the friction-generating component 22, the elastic rubber region 91 adheres to the main shaft region 38 of the piston rod 15 over its entire circumference, while it is elastically deformed radially towards an outward side.

[0067] In a state where the piston rod 15 is mounted in this manner, the smallest inner diameter region 137, a portion of the distal end conical region 139 on the side of the smallest inner diameter region 137, and a portion of the base end conical region 141 on the side of the smallest inner diameter region 137, serve as a lip region 155 in the electrostatic rubber region 91, which comes into sliding contact with the main shaft region 38 of the piston rod 15. In other words, the lip region 155, which comes into sliding contact with the piston rod 15, is formed in the elastic rubber region 91.

[0068] The friction-generating component 22, in a state in which it is mounted on the piston rod 15, the piston rod 15, the bottom region and the plurality of recessed areas 60 of the small-diameter hole region 57 of the rod guide main body 49 and the collar 63 form a chamber 151. At this time, in the friction-generating component 22, the inner circumferential surface 140 of the base-end conical region 141 thereof, the inner circumferential surface 142 of the uniform diameter region 143, the inner circumferential surface 144 of the conical region 145 and the outer bottom surface 105 of the annular disk region 101 form the chamber 151.In the elastic rubber area 91, the remaining portion, which does not form the lip area 155 on one side opposite the smallest inner diameter area 137 of the base-end conical area 141, serves as a pressure-receiving area 156 that receives the pressures in chamber 151 and the communicating single-sided chamber 16 via the communication path 64 in the radial direction. Thus, on the inner circumferential side of the elastic rubber area 91, the lip area 155 is formed on the side of the mounting component 21, and the pressure-receiving area 156, which receives the pressure in the single-sided chamber 16, is formed on the side of the single-sided chamber 16.

[0069] In the friction-generating component 22 in a state in which it is mounted on the piston rod 15, the inner circumferential surface 138 of the distal end conical region 139 of the elastic rubber region 91 thereof, the distal end surface 134 of the distal end region 135, the outer circumferential surface 126 of the outer circumferential region 127, the inner circumferential surface 106 of the fixing region 102 and a part of the distal end surface 107 and the outer circumferential surface 108 on the side of the distal end surface 107 form the chamber 85.

[0070] Meanwhile, chamber 151 communicates with the single-sided chamber 16 via communication path 64 between the collar 63 and the piston rod 15. Conversely, chamber 151 communicates with chamber 85 and reservoir chamber 13 via communication paths 152 inside the penetration holes 111 of the friction-generating component 22. The cross-sectional areas of the communication paths 152 are smaller than the cross-sectional area of ​​communication path 64. Therefore, the pressure loss due to communication paths 152 is higher than the pressure loss due to communication path 64. Since the communication paths 152 allow single-sided chamber 16, chamber 151, and chamber 85 to communicate with each other at all times, hydraulic fluid is directed from single-sided chamber 16 to chamber 85. Accordingly, the communication paths 152 prevent cold welding ("galling") due to poor lubrication of the sealing component 21.Additionally, the communication pathways 152 release incorporated air into the single-sided chamber 16.

[0071] In the shock absorber 11, when the piston rod 15 moves towards the extension side, where the overall length of the shock absorber 11 extends, the piston 18 moves towards the single-sided chamber 16 side, and the pressure in the single-sided chamber 16 increases, the pressure in chamber 151 also increases via the communication path 64. However, the pressure increase in chamber 85 via the communication paths 152 can be delayed with a high pressure drop. At this time, the upstream side of the elastic rubber section 91, in the direction of flow of a hydraulic fluid, becomes chamber 151, and its downstream side becomes chamber 85. Furthermore, chamber 85, located between the downstream side of the elastic rubber section 91 and the reservoir chamber 13, is under an internal pressure that is lower than the internal pressures in the single-sided chamber 16 and chamber 151.Regarding the relationship between the passage areas of communication paths 152 and communication path 64, communication paths 152 are larger than communication path 64. Communication paths 152 are not necessary.

[0072] In the elastic rubber area 91, the pressure-absorbing area 156 of the flat plate area 141 primarily absorbs an outward radial force due to the differential pressure generated in this way between the single-sided chamber 16 and chamber 151, and between chamber 85 and reservoir chamber 13. Furthermore, when the differential pressures generated in this way between the single-sided chamber 16 and chamber 151, and between chamber 85 and reservoir chamber 13, reach a predetermined pressure in the elastic rubber area 91, the pressure-absorbing area 156 of the flat plate area 141 is deformed outward in the radial direction due to the absorbed pressure. This creates a radial gap between the pressure-absorbing area 156 and the piston rod 15, allowing communication between chamber 151 on the upstream side and chamber 85 on the downstream side via this gap.This means that the elastic rubber area 91 is designed so that the chamber 151 on the upstream side and the chamber 85 on the downstream side can communicate with each other when the differential pressure between the single-sided chamber 16 and the reservoir chamber 13 reaches a predetermined pressure.

[0073] In the shock absorber 11 of the first embodiment described above, when the piston rod 15 moves towards the extension side, a damping force with opening characteristics is generated due to a fixing opening (not illustrated) in a region of low piston speed, and the poppet valve 42 is separated from the piston 18, generating a damping force with valve characteristics in a region of high piston speed. Additionally, when the piston rod 15 moves towards the contraction side, a damping force with opening characteristics is generated due to a (not illustrated) mounting opening in a region of low piston speed, and the poppet valve 41 is separated from the piston 18, generating a damping force with valve characteristics in a region of high piston speed.

[0074] In this context, with regard to a hydraulic damping region that generates a hydraulic damping force due to an installation port (not illustrated) and the poppet valves 41 and 42 described above, a damping force is rarely generated in an extremely low velocity region of a lower piston velocity due to an installation port (not illustrated) and the poppet valves 41 and 42. Therefore, frictional resistance at the piston rod 15 due to the sealing component 21 and the friction-generating component 22, and frictional resistance of the piston 18 against the cylinder 12, become the main sources of a damping force.

[0075] The foregoing patent document 1 describes a fluid pressure shock absorber in which a friction-generating component is provided that comes into sliding contact with a piston rod, and a communication path is provided that allows both sides of this friction-generating component to communicate with each other in the axial direction. In this fluid pressure shock absorber, since a communication path is provided that allows both sides of the friction-generating component to communicate with each other in the axial direction, essentially both sides of the friction-generating component are held under the same pressure in the axial direction.

[0076] Incidentally, a shock absorber requires that a frictional force be generated by the friction-generating component without producing a hydraulic damping force, within a small amplitude range where the amplitudes of the piston rod and piston are extremely small. This is because the generation of a braking force is limited in a typical range where the amplitudes of the piston rod and piston become larger than those in the small amplitude range (the aforementioned hydraulic damping range). This is because there is a possibility of impaired vehicle handling if this type of shock absorber is used in a suspension system where the frictional force from the friction-generating component is significant within a typical range.Since an axial force is generated by the friction-generating component due to sliding resistance (hereinafter referred to as a sliding force), the piston speed, which is insufficient in a conventional shock absorber, supplements a damper axial force in an extremely low speed range, thus improving ride quality and steering stability. However, the sliding force of the friction-generating component is generated uniformly, without depending on the piston speed of the shock absorber in regions other than an extremely low speed range.

[0077] In the shock absorber 11 of the first embodiment, in the small amplitude regions of the piston rod 15 and the piston 18, where the hydraulic damping force is not generated because the pressures in the single-sided chamber 16 and the reservoir chamber 13 are approximately equivalent, the lip area 155 of the elastic rubber area 91 of the friction-generating component 22 comes into contact with the main shaft area 38 of the piston rod 15 in a bonded state. Thus, the friction-generating component 22 generates a high sliding resistance to the piston rod 15.

[0078] In contrast, during an extension stroke and a contraction stroke in a typical region (the aforementioned hydraulic damping region) with a larger amplitude than the small amplitude region, the piston velocity increases, the pressure in the single-sided chamber 16 becomes higher than the pressure in the reservoir chamber 13, and the pressure in the chamber 151, which communicates with the single-sided chamber 16 via communication path 64, also increases similarly. Conversely, the pressure in the chamber 85, which communicates with the chamber 151 via communication paths 152 with a high pressure drop, does not increase, and the chamber 85 is under an internal pressure lower than the internal pressures in the single-sided chamber 16 and the chamber 151. At this time, the chamber 85, located between the downstream side of the elastic rubber region 91 and the reservoir chamber 13, becomes a low-pressure chamber with an internal pressure lower than the internal pressure in the single-sided chamber 16.

[0079] The elastic rubber area 91 receives the pressures in the single-sided chamber 16 and the chamber 151, which are generated in this way and are higher than those in the chamber 85 and the reservoir chamber 13 in the pressure-receiving area 156 on the side of the single-sided chamber 16 of the lip area 155, which comes into sliding contact with the piston rod 15 and is deformed outwards in the radial direction such that a binding force with respect to the main shaft area 38 of the piston rod 15 is reduced and the sliding resistance decreases. In other words, the elastic rubber area 91 receives a force outwards in the radial direction due to differential pressures between the single-sided chamber 16 and the chamber 151 and between the chamber 85 and the reservoir chamber 13, so that a binding force with respect to the main shaft area 38 of the piston rod 15 is reduced and the sliding resistance decreases.

[0080] As the piston speed continues to increase and the differential pressures between the single-sided chamber 16 and chamber 151, and between chamber 85 and reservoir chamber 13, reach a predetermined pressure, the elastic rubber section 91 is separated radially from the main shaft section 38 of the piston rod 15. This allows the single-sided chamber 16 and chamber 151 on the upstream side, and chamber 85 and reservoir chamber 13 on the downstream side, to communicate with each other in the direction of flow of a hydraulic fluid. At this point, there is no longer any sliding resistance on the piston rod 15.

[0081] In this way, if the friction-generating component 22 produces a sliding force corresponding to the piston speed with respect to the piston rod 15, advantageous working characteristics can be obtained and impairment of the driving quality performance of a vehicle using this shock absorber 11 due to excessive sliding force can be mitigated.

[0082] This means that, in order to achieve favorable ride and steering quality, in the shock absorber 11, in a region of extremely low piston speed where an axial force (hereinafter referred to as an oil pressure force) is rarely generated due to pressure loss through a working fluid, the friction-generating component 22 can apply an appropriate sliding force to the piston rod 15. Meanwhile, in a region where the piston speed increases and an oil pressure force is generated (the aforementioned hydraulic damping region), the sliding force with respect to the piston rod 15 of the friction-generating component 22 can be reduced to a low level. In this way, the shock absorber 11 can generate the necessary sliding force in an extremely low speed region and can reduce the sliding force in a region where an oil pressure force is generated.In other words, a necessary sliding force can be generated in an extremely low speed range, and a sliding force can be reduced in a region where an oil pressure force is generated. Accordingly, advantageous operating characteristics can be obtained, and a deterioration in the ride quality performance of a vehicle using the shock absorber 11 can be mitigated.

[0083] Additionally, as described above, since the chamber 85 between the downstream side of the elastic rubber area 91 and the reservoir chamber 13 becomes a low-pressure chamber with an internal pressure lower than the internal pressure in the single-sided chamber 16, the aforementioned differential pressure can advantageously be generated in the elastic rubber area 91.

[0084] Additionally, since chamber 85 communicates with reservoir chamber 13, chamber 85 can be kept under a low pressure and the aforementioned differential pressure can be advantageously generated in the elastic rubber area 91.

[0085] Additionally, since the lip area 155, which comes into sliding contact with the piston rod 15, is formed in the elastic rubber area 91, a frictional force can be advantageously generated when a frictional force is generated.

[0086] Additionally, the lip area 155, which comes into sliding contact with the piston rod 15, is formed on the side of the sealing component 21 on the inner circumferential side of the elastic rubber area 91 in the axial direction. The pressure-bearing area 156, which absorbs the pressure in the single-sided chamber 16 via the chamber 151, is formed on the side of the single-sided chamber 16 on the inner circumferential side of the elastic rubber area 91 in the axial direction. For this reason, the elastic rubber area 91 can have a compact structure. (Second embodiment)

[0087] Next, a second embodiment according to the present invention is described, focusing on parts that differ from those in the first embodiment, mainly based on Fig. 4 and Fig. 5. Parts common to the first embodiment are expressed by the same names and the same reference numerals.

[0088] In a shock absorber 11A of the second embodiment, a friction generating component 22A is provided instead of the friction generating component 22 in the first embodiment, and a rod guide 20A with a rod guide main body 49A, which differs partially from the rod guide main body 49, is provided instead of the rod guide 20 in the first embodiment. Fig. 4 and Fig. Figure 5 also illustrates the friction generating component 22A in a natural state before the piston rod 15 is inserted through it, and the outer circumferential surface 37 of the main shaft area 38 of the piston rod 15 in the case in which it is inserted through it is indicated by an imaginary line (two-dot dashed line).

[0089] The friction-generating component 22A is located on the inward side of the sealing component 21 in the cylinder's inward / outward direction and between the sealing component 21 and the rod guide 20A. The friction-generating component 22A has an annular shape, and the piston rod 15 is inserted through its inner side in such a way that it can slide. The friction-generating component 22A is mounted and fixed to the rod guide 20A in its outer circumferential region. The inner circumferential region of the friction-generating component 22A comes into sliding contact with the outer circumferential region of the piston rod 15, generating frictional resistance in the piston rod 15. The friction-generating component 22A is not intended to seal and is positioned on a side defined by the sealing component 21 in the cylinder 12.

[0090] The main body of the rod guide 49A has a small-diameter hole area 57A, which differs in part from the small-diameter hole area 57 in the first embodiment. The small-diameter hole area 57A does not have a recessed area 60 formed therein and has a circular shape with a smaller diameter than the intermediate-diameter hole area 56 or a larger diameter than the smallest-diameter hole area 58.

[0091] The friction-generating component 22A is press-fitted into the intermediate diameter hole area 56 of the rod guide main body 49A of the rod guide 20A. At this time, the friction-generating component 22A abuts the bottom surface of the bottom area of ​​the intermediate diameter hole area 56. The friction-generating component 22A is located on an inward side in the cylinder inward / outward direction of the sealing component 21. In the friction-generating component 22A, the inner circumferential area comes into pressure contact with the outer circumferential surface 37 of the main shaft area 38 of the piston rod 15 and generates frictional resistance against the piston rod 15.

[0092] As in Fig. As illustrated in Figure 5, the friction-generating component 22A is an integrated component consisting of an annular elastic rubber section 91A, made of an elastic rubber material such as nitrile rubber or fluorocarbon rubber, and an annular metal base section 92A to which the elastic rubber section 91A is rigidly attached. The friction-generating component 22A is mounted on the base section 92A in the intermediate diameter hole area 56 of the rod guide 20A. The friction-generating component 22A comes into sliding contact with the outer circumferential surface 37 of the main shaft area 38 of the piston rod 15 within the elastic rubber section 91A. The base section 92A maintains the shape of the elastic rubber section 91A and provides the rigidity for fixing it to the rod guide 20A.

[0093] The friction generating component 22A in a natural state is described with reference to Fig. 5 described. In the friction generating component 22A, the base area 92A has a cylindrical shape with a bottom and a lid, which is composed of an annular disk area 200 having a perforated flat disk plate shape, an annular fixing area 201 extending axially to one side from the outer circumferential side of the annular disk area 200, and an annular disk area 202 having a perforated flat disk plate shape extending inwards in a radial direction from one side opposite to the annular disk area 200 in the axial direction of the fixing area 201.

[0094] The fixing area 201 extends axially between the annular disk areas 200 and 202. The fixing area 201 is formed in a state where it is coaxial with the annular disk areas 200 and 202. The center axes of the annular disk areas 200 and 202 and the fixing area 201 coincide with each other. The annular disk areas 200 and 202 are parallel to each other, and the fixing area 201 is perpendicular to them. For example, in base area 92A, the annular disk areas 200 and 202 are formed from a cylindrical material by plastic deformation.

[0095] The annular disk area 200 has an inner base surface 203, which consists of a circular flat surface on the side of the fixing area 201 in the axial direction; an inner circumferential surface 204, which consists of a cylindrical surface on one side opposite to the fixing area 201 in the radial direction; and an outer base surface 205, which consists of a circular flat surface on one side opposite to the fixing area 201 in the axial direction. The inner circumferential end region and the inner base surface 203 are connected to one end region on the inner circumferential surface 204 in the axial direction, and the inner circumferential end region on the outer base surface 205 is connected to the opposite end region on the inner circumferential surface 204 in the axial direction.

[0096] The fixing area 201 has an inner circumferential surface 206, which is composed of a cylindrical surface on the annular disk area 200 side in the radial direction, and an outer circumferential surface 208, which is composed of a cylindrical surface on one side opposite to the annular disk area in the radial direction. The annular disk area 200 has an inner rounded chamfer 209 with a torus shape, which connects the inner base surface 203 and the inner circumferential surface 206 on one side where they are close to each other, and also has an outer rounded chamfer 210 with a toric shape, which connects the outer base surface 205 and the outer circumferential surface 208 on one side where they are close to each other. In the present embodiment, a structure with a rounded chamfer 210 is used, but this is not essential.

[0097] The annular disk area 202 has an inner base surface 213, which consists of a circular flat surface on the side of the fixing area 201 in the axial direction; an inner circumferential surface 214, which consists of a cylindrical surface on one side opposite to the fixing area 201 in the radial direction; and an outer base surface 215, which consists of a circular flat surface on one side opposite to the fixing area 201 in the axial direction. The inner circumferential end region of the inner base surface 213 is connected to one end region on the inner circumferential surface 214 in the axial direction, and the inner circumferential end region on the outer base surface 215 is connected to the opposite end region on the inner circumferential surface 214 in the axial direction.

[0098] The annular disc area 202 has an inner rounded chamfer 219 with a toros shape, which connects the inner bottom surface 213 and the inner circumferential surface 206 on one side where they are close to each other, and also has an outer rounded chamfer 220 with a toros shape, which connects the outer bottom surface 215 and the outer circumferential surface 208 on one side where they are close to each other.

[0099] In the base area 92A, the center axes of the inner bottom surfaces 203 and 213, the inner circumferential surfaces 204 and 214, the outer bottom surfaces 205 and 215, the inner circumferential surface 206, the outer circumferential surface 208, the inner rounded chamfers 209 and 219, and the outer rounded chamfers 210 and 220 coincide. The inner bottom surfaces 203 and 213 and the outer bottom surfaces 205 and 215 expand such that they are orthogonal to the center axes. The inner circumferential surface 204 also has the smallest diameter in the annular disk area 200, and the inner circumferential surface 214 also has the smallest diameter in the annular disk area 202. In the base area 92A, the inner diameter of the inner circumferential surface 214 of the annular disk area 202 is larger than the inner diameter of the inner circumferential surface 204 of the annular disk area 200.Thus, the inner circumferential surface 204 has the smallest diameter in the base area 92A.

[0100] Penetration holes 221, which penetrate the outer base surface 205 from the inner base surface 203, are formed in the annular disc area 200 of the base area 92A. The penetration holes 221 are parallel to the center axes of the annular disc areas 200 and 202 and the fixing area 201, i.e., the center axis of the base area 92A, and are parallel to the center axis of the friction-generating component 22A. A plurality of penetration holes 221 are formed at equal intervals in the circumferential direction of the annular disc area 200. The present embodiment illustrates a structure in which a plurality of penetration holes 221 are provided, but a single penetration hole 221 may also be provided.

[0101] Penetration holes 222, which penetrate the outer circumferential surface 208 from the inner circumferential surface 206, are formed in the fixing area 201 of the base area 92A. The penetration holes 222 are formed axially on the annular disc area 202 side of the fixing area 201 and extend radially along the fixing area 201. A plurality of penetration holes 222 are formed at equal intervals along the circumferential direction of the fixing area 201.

[0102] The elastic rubber area 91A has a torus shape with a central axis that coincides with that of the base area 92A. The elastic rubber area 91A has a main body area 121A, which is arranged on an inward side in the radial direction of the fixing area 201 of the base area 92A and is formed on the side of the fixing area 201 of the annular disc area 202 in the axial direction, an inner coated area 122A, which projects outward in the axial direction from the end area of ​​the inner circumferential area of ​​the main body area 121A on the annular disc area 202 side and is formed on the inner circumferential side of the annular disc area 202, and a distal end lip area 224, which projects on one side opposite to the inner coated area 122A in the axial direction from the main body area 121A.

[0103] In the main body region 121A, an outer circumferential region 227 with an outer circumferential surface 226 is separated inwards in the radial direction from the inner circumferential surface 206 of the fixing region 201 of the base region 92A over its entire surface. The main body region 121A is fixed to the inner bottom surface 213 of the annular disk region 202 of the base region 92A on a base end-side fixing attachment surface 228, which is axially connected to one side of the outer circumferential surface 226. The outer circumferential surface 226 has a conical shape, increasing in diameter towards the base end-side fixing attachment surface 228 in the axial direction. The outer circumferential surface 226 is exposed but not fixed to the base region 92A. Thus, the elastic rubber area 91A overlaps the inner circumferential side of the tubular fixing area 201 in the axial direction and is designed so that it is completely separated in the radial direction.

[0104] The inner coated area 122A is firmly attached to the inner circumferential surface 214 of the annular disc area 202 on an inner circumferential fixing mounting surface 229, which is connected with one side opposite the outer circumferential surface 226 to the base end fixing mounting surface 228. In the elastic rubber area 91A, a portion that comes into contact with the annular disc area 202 is firmly attached to the base area 92A over its entire surface. The elastic rubber area 91A is firmly attached only to the annular disc area 202 with respect to the base area 92A.

[0105] The elastic rubber area 91A has a distal end area 235 which includes a distal end surface 234 that is exposed without being fixed to the base area 92A in the axial direction opposite to the base end fixing mounting surface 228 of the flat plate area 121A. The distal end area 235 is positioned on the side of the annular disc area 202 axially from the annular disc area 200, and the distal end surface 234 faces the inner base surface 203.

[0106] The elastic rubber section 91A has a distal end lip section 224 on one side opposite the outer circumferential surface 226 in the radial direction from the distal end surface 234 of the distal end section 235. The distal end lip section 224 extends axially from the distal end surface 234 to the side of the annular disc section 200 and abuts the penetration holes 221 on the inner bottom surface 203 of the annular disc section 200 on an inward side in the radial direction. The distal end lip section 224 has a torus shape that abuts the inner bottom surface 203 around the entire circumference of the elastic rubber section 91A in the circumferential direction. The distal end lip section 224 has a shape that tapers in diameter towards a widening distal end. The distal end lip area 224 is reduced in thickness in the radial direction towards the widening distal end side.

[0107] Within the elastic rubber area 91A, an inner circumferential area 236 is also exposed to the base area 92a, without being firmly attached. The inner circumferential area 236 of the elastic rubber area 91A has the smallest diameter within the elastic rubber area 91A.The inner circumferential region 236 of the elastic rubber region 91A has a smallest inner diameter region 237, which has the smallest diameter in the friction generating component 22A, a distal end conical region 239, which has a conical inner circumferential surface 238 that widens as it increases in diameter while being separated from the smallest inner diameter region 237 to the side of the distal end surface 234 in an axial direction, and a conical base end cone region 241, which has a conical inner circumferential surface 240 that widens as it increases in diameter while being separated from the smallest inner diameter region 237 to a side opposite the distal end surface in an axial direction from the smallest inner diameter region 237.The smallest inner diameter region 237, the distal end conical region 239, and the base end conical region 241 are formed within the main body region 121a. The distal end lip region 224 is located between the distal end conical region 239 and the distal end region 235.

[0108] Additionally, in the elastic rubber region 91A, the inner circumferential region 236 has a uniform diameter region 243, which has a cylindrically shaped inner circumferential surface 242, one side of which faces opposite the smallest inner diameter region 237 on the inner circumferential surface 240, and a conical region 245, which has a conical inner circumferential surface 244 that increases in diameter when separated from the inner circumferential surface 242 on one side opposite the inner circumferential surface 240. The inner circumferential surface 244 is connected to the outer bottom surface 215 of the annular disk region 202.

[0109] In other words, the elastic rubber region 91A comprises the smallest inner diameter region 237, the distal end conical region 239, and the base end conical region 241 on both sides of the smallest inner diameter region 237 in the axial direction, and the uniform diameter region 243 and the conical region 245 on the inner circumferential side. A boundary section between the distal end conical region 239 and the base end conical region 241 serves as the smallest inner diameter region 237. With respect to the distal end conical region 239 and the base end conical region 241, the distal end conical region 239 is arranged on one side far from the annular disc region 202 of the base region 92A, and the base end conical region 241 is arranged on one side close to the annular disc region 202 in the axial direction of the elastic rubber region 91A.The distal end conical region 239 is located on one side near the annular disc region 200 of the base region 92A, and the base end conical region 241 is located on one side far from the annular disc region 200. Furthermore, in other words, the elastic rubber region 91A includes the smallest inner diameter region 237, the distal end conical region 239 (which expands as its diameter increases axially towards the side of the single-sided chamber 16 from the smallest inner diameter region 237), and the base end conical region 241 (which expands as its diameter increases axially towards one side opposite the single-sided chamber 16 from the smallest inner diameter region 237).

[0110] All of the smallest inner diameter region 237, the distal end conical region 239, the base end conical region 241, the uniform diameter region 243, and the conical region 245 have a torus shape that is continuous over the entire circumference in the circumferential direction of the elastic rubber region 91A. Since the elastic rubber region 91A has a central axis that coincides with that of the base region 92A, the outer circumferential surface 226, the distal end surface 234, the inner circumferential surface 238, the smallest inner diameter region 237, the inner circumferential surface 240, the inner circumferential surface 242, the inner circumferential surface 244, and the distal end lip region 224 have a central axis that coincides with that of the base region 92A.

[0111] As in Fig. As illustrated in Figure 4, the friction-generating component 22A, which has the aforementioned structure, is mounted and fixed to the intermediate diameter hole region 56 (fixing target part) by pressing it in from the side of the large diameter hole region 54 of the rod guide 20 in a position in which the annular disk region 200 of the base region 92A is positioned on an inward side in the cylinder-inward / outward direction and the annular disk region 202 is positioned on an outward side in the cylinder-inward / outward direction. At this time, as shown in Figure 4, the friction-generating component 22A is mounted and fixed to the intermediate diameter hole region 56 (fixing target part) by pressing it in from the side of the large diameter hole region 54 of the rod guide 20 in a position in which the annular disk region 200 of the base region 92A is positioned on an inward side in the cylinder-inward / outward direction. Fig.As illustrated in Figure 5, in the friction-generating component 22A, the fixing area 201 of the base area 92A is mounted on the inner circumferential surface of the intermediate diameter hole area 56 of the outer circumferential surface 208. In the friction-generating component 22A, the annular disk area 200 abuts the bottom surface of the bottom area of ​​the intermediate diameter hole area 56 on the outer bottom surface 205. In this state, the penetration holes 221 of the annular disk area 200 are radially oriented on one side from the inner circumferential surface of the small diameter hole area 57A. The penetration holes 221 of the annular disk area 200 open within the small diameter hole area 57A. Additionally, the penetration holes 222 of the fixing area 201 open within the conical hole area 55.

[0112] On the inner circumferential side of the elastic rubber area 91A, the distal end conical area 239 is arranged on one side in the cylinder-inward / outward direction starting from the smallest inner diameter area 237, and the base end conical area 241 is arranged on an outer side in the cylinder-inward / outward direction starting from the smallest inner diameter area 237. The base area 92A has a tubular fixing area 201 for fixing the friction-generating component 22A to the end diameter hole area 56 of the rod guide 20 (target part).

[0113] The main shaft section 38 of the piston rod 15 is inserted by the friction-generating component 22A with a predetermined interference on the inside of the elastic rubber section 91A. Thus, the elastic rubber section 91A adheres to the main shaft section 38 of the piston rod 15 over its entire circumference, while it is elastically deformed radially on an outer side.

[0114] In a state in which it is mounted on the piston rod 15 in this manner, the smallest inner diameter region 237, a part of the distal end conical region 239 on the side of the smallest inner diameter region 237, and a part of the base end conical region 241 on the side of the smallest inner diameter region 237 serve as a lip region 255 in the elastic rubber region 91A, which comes into sliding contact with the main shaft region 38 of the piston rod 15.

[0115] Additionally, when mounted on the piston rod 15, the friction-generating component 22A, the piston rod 15, the small-diameter hole area 57A of the rod guide main body 49A, and the collar 63 form a chamber 151A that communicates with the communication path 64. At this time, the friction-generating component 22A, the inner circumferential surface 238 of the distal end conical area 239 thereof, the distal end lip area 224, the inner circumferential surface 204, and the outer bottom surface 205 of the annular disc area 200 form the chamber 151A. In the elastic rubber area 91A, the remaining part, which does not form the lip area 255 on one side opposite to the smallest inner diameter area 237 of the distal end conical area 239, serves as a pressure receiving area 256, which receives the pressures in the chamber 151A and the single-sided chamber 16, which communicates with it, via the communication path 64 in the radial direction.Thus, on the inner circumferential side of the elastic rubber area 91A, the lip area 255 is formed on the side of the sealing component 21 in the axial direction, and the pressure absorption area 256, which absorbs the pressure in the single-sided chamber 16, is formed on the side of the single-sided chamber 16 in the axial direction.

[0116] In the friction-generating component 22A, when mounted on the piston rod 15, the inner circumferential surface 240 of the base-end conical region 241 of the elastic rubber region 91A, the inner circumferential surface 242 of the uniform diameter region 243, the inner circumferential surface 244 of the conical region 245, the outer bottom surface 215 of the annular disc region 202, the outer rounded chamfer 220, and a portion of the outer circumferential surface 208 on the side of the outer rounded chamfer 220 form an oil storage chamber 85A. The oil lip 73 of the sealing component 21 scrapes hydraulic fluid adhering to the piston rod 15 at the moment the piston rod 15 extends and stores hydraulic fluid in this oil storage chamber 85A. The oil storage chamber 85A communicates with the reservoir chamber 13 at all times via the communication hole 62 and the pressure in it is the same as that in the reservoir chamber 13.

[0117] In the friction-generating component 22A, when mounted on the piston rod 15, the distal end lip region 224, the distal end surface 234 of the distal end region 235, the outer circumferential surface 226 of the outer circumferential region 227, the inner bottom surface 203 of the annular disc region 200, the inner rounded chamfer 209, the inner circumferential surface 206 of the fixing region 201, and the inner rounded chamfer 219 of the annular disc region 202 form an inner chamber 261 (low-pressure chamber). The inner chamber 261 communicates with the oil storage chamber 85A and the reservoir chamber 13 at all times via communication paths 253 within the penetration holes 222, and the pressure therein is the same as that in the reservoir chamber.

[0118] Meanwhile, chamber 151A communicates with communication path 64 between collar 63 and piston rod 15. Simultaneously, chamber 151A communicates with inner chamber 261 via communication paths 252 within the penetration holes 221 of friction-generating component 22A. The cross-sectional areas of the communication paths 252 are smaller than those of communication path 64. Therefore, the pressure loss due to communication paths 252 is higher than the pressure loss due to communication path 64. Additionally, the cross-sectional areas of the communication paths 253, which allow inner chamber 261 and oil storage chamber 85A to communicate with each other, are larger than those of communication paths 252, and there is practically no pressure loss due to communication paths 253.In the present embodiment, a constitution is provided in which the communication paths 252 are provided, but this is not essential.

[0119] Communication paths 252 allow single-sided chamber 16 and chamber 151A to communicate with inner chamber 261 at all times, and communication paths 253 allow inner chamber 261 to communicate with oil storage chamber 85A and reservoir chamber 13 at all times. Communication paths 252 and 253 carry hydraulic fluid from single-sided chamber 16 to oil storage chamber 85. This prevents seizing due to poor lubrication of the sealing component 21. Additionally, communication paths 252 and 253 discharge any air incorporated into single-sided chamber 16.

[0120] In the shock absorber 11A, when the piston rod 15 moves to the extension side, where the overall length of the shock absorber 11A expands, and to the contraction side, where it contracts, the piston 18 moves to the side of the single-sided chamber 16 and the pressure in the single-sided chamber 16 increases, the pressure in the chamber 151A also increases via the communication path 64, but the increase in pressure in the inner chamber 261 via the communication paths 252 can be accompanied by a high pressure loss in a delayed state. At this time, the upstream side of the elastic rubber section 91A in the flow direction of a hydraulic fluid becomes chamber 151A, and its downstream side becomes the inner chamber 261. The inner chamber 261, located between the downstream side of the elastic rubber section 91A and the reservoir chamber 13, is under an internal pressure that is lower than the internal pressures in the single-sided chamber 16 and the chamber 151.

[0121] In the elastic rubber region 91A, the pressure-absorbing region 256 of the distal end conical region primarily absorbs an outward radial force due to the differential pressures generated in this way between the single-sided chamber 16, the chamber 151A, the inner chamber 261, the oil storage chamber 85A, and the reservoir chamber 13. Furthermore, in the elastic rubber region 91A, when the differential pressures generated in this way between the single-sided chamber 16, the chamber 151A, the inner chamber 261, the oil storage chamber 85A, and the reservoir chamber 13 reach a predetermined pressure, the pressure-absorbing region 256 of the distal end conical region 239 deforms outward in the radial direction due to the absorbed pressure.Accordingly, a radial gap is created between the pressure-receiving area 256 and the piston rod 15, and thus the chamber 151A on the upstream side and the oil storage chamber 85A on the downstream side communicate with each other via this gap. That is to say, the elastic rubber area 91A is designed such that the chamber 151A on the upstream side and the inner chamber 261 on the downstream side can communicate with each other when the differential pressure between the single-sided chamber 16 and the reservoir chamber 13 reaches a predetermined pressure.

[0122] In the shock absorber 11A of the second embodiment described above, with respect to a hydraulic damping region that generates a hydraulic damping force due to a locking orifice (not illustrated) and the poppet valves 41 and 42, a damping force due to a locking orifice (not illustrated) and the poppet valves 41 and 42 is rarely generated in an extremely low-speed region of a lower piston speed. Therefore, an elastic force and frictional resistance at the piston rod 15 due to the sealing component 21 and the friction-generating component 22A, and a frictional resistance of the piston 18 against the cylinder 12, are the main sources of generating a damping force.

[0123] In the shock absorber 11A of the second embodiment, in the small amplitude regions of the piston rod 15 and the piston 18, where no hydraulic damping force is generated, the pressures in the single-sided chamber 16 and the reservoir chamber 13 are approximately equivalent to each other. For this reason, the lip region 255 of the elastic rubber region 91A of the friction-generating component 22A comes into contact with the main shaft region 38 of the piston rod 15 in a bonded state. Thus, the friction-generating component 22A generates a high sliding resistance to the piston rod 15.

[0124] In contrast, during an extension stroke and a contraction stroke in a typical region (the aforementioned hydraulic damping region) with a larger amplitude than the small amplitude region, when the piston velocity increases and the pressure in the single-sided chamber 16 becomes higher than the pressure in the reservoir chamber 13, the pressure in the chamber 151A, which communicates with the single-sided chamber 16 via communication path 64, also increases similarly. Conversely, the pressure in the inner chamber 261, which communicates with the chamber 151A via communication paths 252 with a high pressure drop, does not increase, and the internal pressure of the inner chamber 261 is lower than the internal pressures in the single-sided chamber 16 and the chamber 151A.At this time, the inner chamber 261 between the downstream side of the elastic rubber area 91A and the reservoir chamber 13 becomes a low-pressure chamber with an internal pressure lower than the internal pressure in the single-sided chamber 16.

[0125] The elastic rubber area 91A absorbs the pressures in the single-sided chamber 16 and the chamber 151A, which are generated in this way and are higher than those in the inner chamber 261, the oil storage chamber 85A and the reservoir chamber 13 in the pressure-absorbing area 256 on the side of the single-sided chamber 16 of the lip area 255, which comes into sliding contact with the piston rod 15 and is deformed outwards in the radial direction so that a tensile force with respect to the main shaft area 38 of the piston rod 15 is reduced and a sliding resistance decreases.

[0126] As the piston speed continues to increase and the differential pressures between the single-sided chamber 16, chamber 151A, inner chamber 261, oil storage chamber 85A, and reservoir chamber 13 reach a predetermined pressure, the elastic rubber section 91A is separated radially from the main shaft section 38 of the piston rod 15. This allows the single-sided chamber 16 and chamber 151A on the upstream side, and the oil storage chamber 85A and reservoir chamber 13 on the downstream side, to communicate with each other in the direction of hydraulic fluid flow. At this point, there is no longer any sliding resistance between the elastic rubber section 91A and the piston rod 15.

[0127] In this way, in the shock absorber 11A of the second embodiment, similar to the first embodiment, the friction-generating component 22A produces a sliding force corresponding to the piston speed with respect to the piston rod 15. For this reason, the shock absorber 11A of the second embodiment exhibits effects similar to those in the first embodiment.

[0128] Additionally, in the shock absorber 11A of the second embodiment, the base area 92A has a shape that forms the inner chamber 261 under an internal pressure lower than the internal pressure in the single-sided chamber 16. For this reason, the elastic rubber area 91A can be covered by the base area 92A, thus simplifying the handling of the friction-generating component 22A.

[0129] Additionally, due to the structure in which the communication paths 253, which allow the inner chamber 261 and the oil storage chamber 85A to communicate with each other, are formed in the base area 92A, the communication paths 253 can be easily formed.

[0130] Additionally, a structure is used in which the communication paths 252, which allow the single-sided chamber 16 and the inner chamber 261 to communicate with each other, are formed in the base area 92A. For this reason, the communication paths 252 can be formed identically and their characteristics can be adjusted by slightly changing the sizes of the communication paths 252.

[0131] A first aspect of the embodiment described above includes a cylinder filled with a working fluid, an outer tube provided on an outer circumferential side of the cylinder, a reservoir chamber formed between the outer tube and the cylinder, a piston that comes into sliding contact with a surface side of the cylinder and divides the inside of this cylinder into a one-sided chamber and an opposite-sided chamber, a piston rod in which the piston is fixed at one end and extends an opposite end from the cylinder, a sealing element that comes into sliding contact with the piston rod and prevents the working fluid from leaking out of the cylinder, a rod guide provided at a position on one side defined by the sealing element of the cylinder and guiding the cylinder rod, and a friction-generating element provided at a position on one side.which is defined by the cylinder's sealing element and comes into sliding contact with the piston rod. The friction-generating element has an annular elastic rubber section that comes into contact with the piston rod and a base section to which this elastic rubber section is rigidly attached. The elastic rubber section is designed such that an upstream side and a downstream side are able to communicate with each other when a differential pressure between the single-sided chamber of the cylinder and the reservoir chamber reaches a predetermined pressure. Accordingly, it is possible to obtain favorable operating characteristics.

[0132] According to a second aspect, in the first aspect a low-pressure chamber is formed between the downstream side of the elastic rubber area and the reservoir chamber with an internal pressure lower than an internal pressure on the single-sided chamber.

[0133] According to a third aspect, in the second aspect the low-pressure chamber communicates with the reservoir chamber.

[0134] According to a fourth aspect, in any of the first to third aspects, a lip area that comes into sliding contact with the piston rod is formed in the elastic rubber area.

[0135] According to a fifth aspect, in the fourth aspect the lip area on the sealing component side is formed on an inner circumferential side of the elastic rubber area and a pressure receiving area that absorbs pressure from this single-sided chamber is formed on the side of the single-sided chamber. [Industrial applicability]

[0136] It is possible to provide a shock absorber capable of achieving favorable working characteristics by applying the aforementioned shock absorber to relevant areas. Reference symbol list 11, 11A Shock absorber 11 12 cylinders 13 Reservoir chamber 14 Outer tube 15 Piston rod 16 Single-sided chamber 17 Opposite Chamber 18 pistons 20 rod guides 21 Sealing component 22, 22A Friction generating component 85 Chamber (Low-pressure chamber) 91, 91A Elastic rubber area 92, 92A Basic range 155, 255 lip area 156, 256 Pressure absorption range 261 Inner chamber (low-pressure chamber)

Claims

[1] Shock absorber (11, 11A), comprising: a cylinder (12) filled with a working fluid, an outer tube (14) which is provided on an outer circumferential side of the cylinder (12), a reservoir chamber (13) which is formed between the outer tube (14) and the cylinder (12), a piston (18) which comes into sliding contact with a surface side of the cylinder (12) and divides the inside of this cylinder (12) into a one-side chamber (16) and an opposite-side chamber (17), a piston rod (15) to which the piston (18) is fixed at one end and an opposite end extends from the cylinder (12), a sealing component (21) that comes into sliding contact with the piston rod (15) and prevents the working fluid from leaking out of the cylinder (12), a rod guide (20) which is provided at a position on a side defined by the sealing component (21) of the cylinder (12) and guides the piston rod (15), a friction generating component (22, 22A) which is provided at a position on a side defined by the sealing component (21) of the cylinder (12) and comes into sliding contact with the piston rod (15), an oil storage chamber (85A) which is connected to the reservoir chamber (13), an inner chamber (261) which is connected to the oil storage chamber (85A) and the reservoir chamber (13), and a chamber (151A) which is connected to the inner chamber (261), wherein the friction generating component (22, 22A) has an annular elastic rubber area (91, 91A) which comes into contact with the piston rod (15), and a base area (92, 92A) to which this elastic rubber area (91, 91A) is firmly attached, characterized by , that the elastic rubber area (91, 91A) is formed such that the elastic rubber area (91, 91A) is located away from an outer circumferential surface of the piston rod (15) and that an upstream side and a downstream side of the elastic rubber area (91, 91A) are able to communicate with each other when a differential pressure between the single-sided chamber (16), the chamber (151A) of the cylinder (12), the inner chamber (261), the oil storage chamber (85A) and the reservoir chamber (13) decreases and the differential pressure reaches a predetermined pressure, wherein a cross-sectional area of ​​a communication path (152, 252) formed in the base region (92, 92A) is smaller than a cross-sectional area of ​​a communication path (64) between the piston rod (15) and the rod guide (20), and wherein the upstream side and the downstream side communicate with each other via the communication path (64) between the piston rod (15) and the rod guide (20), and the communication path (152, 252) formed in the base area (92, 92A). [2] Shock absorber according to claim 1, wherein a low-pressure chamber (85) with an internal pressure lower than an internal pressure of the single-sided chamber (16) is formed between the downstream side of the elastic rubber area (91, 91A) and the reservoir chamber (13). [3] Shock absorber according to claim 2, wherein the low-pressure chamber (85) communicates with the reservoir chamber (13). [4] Shock absorber according to one of claims 1 to 3, wherein a lip area (155, 255) which comes into sliding contact with the piston rod (15) is formed in the elastic rubber area (91, 91A). [5] Shock absorber according to claim 4, wherein the lip area (155, 255) on the sealing component side is formed on an inner circumferential side of the elastic rubber area (91, 91A), and a pressure receiving area (156, 256) receiving a pressure of this single-sided chamber (16) is formed on the side of the single-sided chamber (16).

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