阅读说明：本技术 缓冲器 (Buffer device ) 是由 青木康浩 于 2020-01-10 设计创作，主要内容包括：该缓冲器具备摩擦产生部件(22),该摩擦产生部件(22)设置在缸(12)的由密封部件(21)划分的一侧的位置并与活塞杆(15)滑动接触,摩擦产生部件(22)具有与活塞杆(15)滑动接触的环状的弹性橡胶部(91)和供弹性橡胶部(91)固接的基座部(92),弹性橡胶部(91)形成为,当缸(12)的一侧室(16)和储存室(13)之间的压力差达到规定压力时,能够连通上游侧和下游侧。(The shock absorber is provided with a friction generating member (22), the friction generating member (22) is arranged at a position on one side of the cylinder (12) divided by a sealing member (21) and is in sliding contact with the piston rod (15), the friction generating member (22) is provided with an annular elastic rubber part (91) in sliding contact with the piston rod (15) and a base part (92) fixedly connected with the elastic rubber part (91), and the elastic rubber part (91) is formed to be capable of communicating the upstream side and the downstream side when the pressure difference between the one side chamber (16) of the cylinder (12) and the storage chamber (13) reaches a specified pressure.)

1. A shock absorber is characterized by comprising:

A cylinder filled with a working fluid;

an outer cylinder provided on an outer peripheral side of the cylinder;

a storage chamber formed between the outer tub and the cylinder;

a piston which is in sliding contact with an inner surface side of the cylinder and divides the inside of the cylinder into a first side chamber and a second side chamber;

the piston is fixed at one end of the piston rod, and the other end of the piston rod extends out of the cylinder;

a seal member that is in sliding contact with the piston rod and prevents leakage of the working fluid to the outside of the cylinder;

a rod guide provided at a position on one side of the cylinder defined by the seal member, for guiding the piston rod;

a friction generating member provided at a position on one side of the cylinder divided by the seal member, and in sliding contact with the piston rod;

the friction generating member has an annular elastic rubber portion in sliding contact with the piston rod and a base portion to which the elastic rubber portion is fixed,

the elastic rubber portion is formed so as to be able to communicate between an upstream side and a downstream side of the elastic rubber portion when a pressure difference between the one-side chamber of the cylinder and the reservoir chamber reaches a predetermined pressure.

2. The buffer of claim 1,

A low pressure chamber having an internal pressure lower than the internal pressure of the one-side chamber is formed between the downstream side of the elastic rubber portion and the reservoir chamber.

3. The buffer of claim 2,

the low pressure chamber is in communication with the reservoir chamber.

4. The buffer of any of claims 1 to 3,

a lip portion that is in sliding contact with the piston rod is formed on the elastic rubber portion.

5. The buffer of claim 4,

the lip portion is formed on the sealing member side on the inner peripheral side of the elastic rubber portion, and a pressure receiving portion that receives the pressure of the one chamber is formed on the one chamber side.

Technical Field

The present invention relates to a buffer.

The present application claims priority based on japanese patent application No. 2019-058113, filed in japan on 26/3/2019, the contents of which are incorporated herein by reference.

Background

A shock absorber including a friction generating member that generates frictional resistance against a moving piston rod in addition to a seal member that prevents leakage of a working fluid is disclosed (for example, see patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4312973

Disclosure of Invention

Problems to be solved by the invention

In a damper, it is desirable to use a friction generating member to obtain good operating characteristics.

Therefore, an object of the present invention is to provide a shock absorber capable of obtaining excellent operation characteristics.

Means for solving the problems

One aspect of the shock absorber of the present invention includes a friction generating member that is provided at a position on one side of a cylinder defined by a seal member and that is in sliding contact with a piston rod, the friction generating member including an annular elastic rubber portion that is in sliding contact with the piston rod and a base portion to which the elastic rubber portion is fixed, the elastic rubber portion being formed so as to be able to communicate between an upstream side and a downstream side of the elastic rubber portion when a pressure difference between a chamber on the one side of the cylinder and a reservoir chamber reaches a predetermined pressure.

Effects of the invention

According to the above-described damper, good operation characteristics can be obtained.

Drawings

Fig. 1 is a sectional view showing a shock absorber according to a first embodiment of the present invention.

Fig. 2 is a partial sectional view showing a piston rod extension side of a shock absorber according to a first embodiment of the present invention.

Fig. 3 is a single-side sectional view showing a main portion of a shock absorber according to a first embodiment of the present invention.

Fig. 4 is a partial sectional view showing a piston rod extension side of a damper according to a second embodiment of the present invention.

Fig. 5 is a one-side sectional view showing a main portion of a damper according to a second embodiment of the present invention.

Detailed Description

[ first embodiment ]

A buffer according to a first embodiment of the present invention will be described below with reference to fig. 1 to 3.

The shock absorber 11 of the first embodiment is a hydraulic shock absorber using a working fluid as a working fluid. More specifically, the shock absorber 11 is a hydraulic shock absorber that uses oil as a working fluid. The shock absorber 11 is used for a suspension device of an automobile.

The shock absorber 11 includes a cylindrical cylinder 12 filled with a working fluid, a bottomed cylindrical outer tube 14 having a larger diameter than the cylinder 12 and provided coaxially with the cylinder 12 on the outer peripheral side of the cylinder 12, and a reservoir chamber 13 formed between the outer tube 14 and the cylinder 12.

Further, the buffer 11 includes: a piston rod 15 disposed on the central axis of the cylinder 12, having one axial end disposed in the cylinder 12 and the other axial end extending outward from the cylinder 12 and the outer cylinder 14; and a piston 18 fixed to one end portion of the piston rod 15 in the axial direction and in sliding contact with an inner surface of the cylinder 12, and dividing the inside of the cylinder 12 into two first side chambers 16 and second side chambers 17.

The piston rod 15 moves integrally with a piston 18, and the piston 18 is connected to one end of the piston rod 15. The other end of the piston rod 15 protrudes outward from the cylinder 12 and the outer cylinder 14. An oil liquid as a working fluid is sealed in the cylinder 12. An oil liquid as a working fluid and a high-pressure gas are sealed in the reservoir chamber 13 between the cylinder 12 and the outer cylinder 14. Instead of the high-pressure gas, air at atmospheric pressure may be sealed in the storage chamber 13. The damper 11 is coupled to a wheel side of the vehicle, for example, an outer cylinder 14, and the piston rod 15 is coupled to a vehicle body side of the vehicle, and damps vibration of the wheel with respect to the vehicle body.

The end position of the cylinder 12 and the outer cylinder 14 on the side from which the piston rod 15 protrudes is located on the outer side (upper side in the vertical direction in fig. 1 to 5) of the cylinder 12 and the outer cylinder 14 in the vertical direction (vertical direction in fig. 1 to 5, hereinafter referred to as the cylinder vertical direction) in the axial direction of the cylinder 12 and the outer cylinder 14, compared to the cylinder 12. The buffer 11 has: a rod guide 20 fitted to the outer portions of the cylinder 12 and the outer cylinder 14 in the cylinder inner-outer direction; and a seal member 21 which is disposed further to the outside in the cylinder inner-outer direction than the rod guide 20 and is fitted to the outside portion in the cylinder inner-outer direction of the outer cylinder 14.

Further, the buffer 11 includes: a friction generating member 22 provided between the seal member 21 and the rod guide 20 on an inner side (lower side in the vertical direction in fig. 1 to 5) in the cylinder inner-outer direction than the seal member 21; and a base valve 23 disposed at an end portion of the cylinder 12 and the outer cylinder 14 on the opposite side of the rod guide 20, the seal member 21, and the friction generating member 22 in the axial direction.

The rod guide 20, the seal member 21, and the friction generating member 22 are all annular. The piston rod 15 is slidably inserted through the respective inner sides of the rod guide 20, the seal member 21, and the friction generating member 22. The rod guide 20 restricts the radial movement of the piston rod 15 and axially movably supports the piston rod 15, and guides the piston rod 15 so as to move only in the axial direction.

The seal member 21 is in sliding contact with the outer periphery of the piston rod 15 that moves in the axial direction at the inner periphery thereof, and prevents the oil in the cylinder 12 and the high-pressure gas in the reservoir chamber 13 and the oil from leaking to the outside from the cylinder 12 and the outer cylinder 14. In other words, the seal member 21 prevents the oil and gas in the cylinder 12 and the outer cylinder 14 from leaking to the outside from the damper 11. The rod guide 20 is provided at a position on one side of the cylinder 12 defined by the seal member 21, and guides the piston rod 15.

The outer peripheral portion of the friction generating member 22 is fitted and fixed to the rod guide 20. The friction generating member 22 is not intended to seal the piston rod 15 by causing the piston rod 15 to generate frictional resistance by sliding contact between the inner peripheral portion thereof and the outer peripheral portion of the piston rod 15. The friction generating member 22 is provided at a position on one side of the cylinder 12 divided by the seal member 21, and is in sliding contact with the piston rod 15.

The outer cylinder 14 has a substantially bottomed cylindrical shape, and the outer cylinder 14 has a cylindrical body member 25 and a bottom member 26 that closes one end side of the cylindrical body member 25 opposite to the projecting side of the piston rod 15. The cylindrical member 25 has a locking portion 28 that protrudes radially inward from the position of the opening 27 on the protruding side of the piston rod 15.

The cylinder 12 is cylindrical. One end side in the axial direction of the cylinder 12 is supported in a fitted state by a base body 30 of a base valve 23, and the base valve 23 is disposed so as to be positioned inside a bottom member 26 of the outer cylinder 14. The other end side in the axial direction of the cylinder 12 is supported in a fitted state by a rod guide 20, and the rod guide 20 is positioned on the opening 27 side of the outer cylinder 14 and fitted thereto.

Oil passages 31, 32 are formed in the base body 30 of the base valve 23, and the oil passages 31, 32 can communicate between the other side chamber 17 in the cylinder 12 and the reservoir chamber 13 between the outer cylinder 14 and the cylinder 12. In the base body 30, a disc valve 33 as a compression side damping valve that can open and close the inner oil passage 31 is disposed on the bottom member 26 side in the axial direction, and a disc valve 34 as a check valve that can open and close the outer oil passage 32 is disposed on the opposite side to the bottom member 26 in the axial direction. These disk valves 33 and 34 are attached to the base body 30 by rivets 35 inserted through the base body 30. In the present embodiment, the disk valves 33 and 34 are configured to be attached to the base body 30 by the rivets 35 inserted through the base body 30, but may be attached by nuts and screws.

The disc valve 33 permits the flow of the hydraulic fluid from the other side chamber 17 to the reservoir chamber 13 side through a passage hole, not shown, of the disc valve 34 and the oil passage 31, generates a damping force, and restricts the reverse flow of the hydraulic fluid. On the other hand, the disc valve 34 allows the flow of the hydraulic fluid from the reservoir chamber 13 to the other side chamber 17 side through the oil passage 32 without resistance, and restricts the reverse flow of the hydraulic fluid. That is, the disc valve 33 is a damping valve that generates a damping force when the oil passage 31 is opened when the piston rod 15 moves to the compression side where the amount of entry into the cylinder 12 and the outer cylinder 14 increases and the piston 18 moves to the other side chamber 17 side and the pressure in the other side chamber 17 increases compared to the pressure in the reservoir chamber 13. That is, when the piston rod 15 moves to the extension side where the amount of projection from the cylinder 12 and the outer cylinder 14 increases, and the piston 18 moves to the one side chamber 16 side and the pressure of the other side chamber 17 drops below the pressure of the reservoir chamber 13, the disc valve 34 opens the oil passage 32. The disc valve 34 is a suction valve that causes the hydraulic fluid to flow from the reservoir chamber 13 into the other side chamber 17 at this time substantially without generating a damping force.

The damping force on the expansion side may be actively generated by the disc valve 34 as a damping valve. Further, these disk valves 33 and 34 may be omitted and used as orifices.

The piston rod 15 has a main shaft portion 38 and an inner end shaft portion 39 inserted into the end portion on the cylinder 12 side and having a smaller diameter than the main shaft portion 38, and the main shaft portion 38 has an outer peripheral surface 37 formed of a cylindrical surface having a constant diameter. A nut 40 is screwed to the inner end shaft portion 39, and the piston 18 and the disk valves 41 and 42 on both sides thereof are attached to the inner end shaft portion 39 by the nut 40.

A side chamber 16 is formed between the piston 18 and the rod guide 20. The first chamber 16 is a rod-side chamber through which the piston rod 15 passes. The other side chamber 17 is formed between the piston 18 and the base valve 23. The other side chamber 17 is a bottom side chamber located on the bottom member 26 side of the cylinder 12. The piston rod 15 does not penetrate the inside of the other side chamber 17.

The piston rod 15 is provided with an annular stopper 47 and a buffer 48 at each portion between the piston 18 and the rod guide 20 of the main shaft portion 38. The piston rod 15 is inserted through the inner peripheral side of the stopper 47. The stopper member 47 is fixed to the main shaft portion 38 by caulking. The piston rod 15 is inserted into the buffer 48. The buffer 48 is disposed between the stopper 47 and the rod guide 20. When the piston rod 15 is fully extended, the shock absorber 48 abuts against the rod guide 20 to alleviate the shock.

The piston 18 is provided with oil passages 44 and 45 that allow communication between the other side chamber 17 on the base member 26 side and the one side chamber 16 on the opposite side to the base member 26 in the axial direction of the cylinder 12. Further, a disc valve 41, which is a compression side damping valve capable of opening and closing the oil passage 44, is disposed on the piston 18 on the side opposite to the bottom member 26 in the axial direction. A disc valve 42 as an extension-side damping valve capable of opening and closing an oil passage 45 is disposed on the piston 18 on the bottom member 26 side in the axial direction.

The disc valve 41 allows the flow of the hydraulic fluid from the other side chamber 17 to the one side chamber 16 via the oil passage 44, while restricting the flow of the hydraulic fluid in the reverse direction. On the other hand, the disc valve 42 permits the flow of the hydraulic fluid from the one side chamber 16 to the other side chamber 17 through the oil passage 45, and restricts the reverse flow of the hydraulic fluid. Between the disc valve 41 and the piston 18, a fixed orifice, not shown, is provided that communicates the other side chamber 17 and the one side chamber 16 via the oil passage 44 even in a state where the disc valve 41 is closed. A fixed orifice, not shown, that communicates the other side chamber 17 and the one side chamber 16 via the oil passage 45 even in a state where the disc valve 42 is closed is also provided between the disc valve 42 and the piston 18.

When the piston rod 15 moves to the compression side and the piston 18 moves to the other side chamber 17 side, and the pressure in the other side chamber 17 rises relative to the pressure in the one side chamber 16, the oil flows from the other side chamber 17 to the one side chamber 16 with a constant flow path area through a fixed orifice (not shown) in a region where the moving speed of the piston 18 (hereinafter, referred to as the piston speed) is slow. This generates a damping force having an orifice characteristic. In the region where the piston speed is high, the disc valve 41 separates from the piston 18, opens the oil passage 44, and causes the oil to flow from the other side chamber 17 to the one side chamber 16 with a flow passage area corresponding to the separation amount from the piston 18. Thereby, a damping force of the valve characteristic is generated.

When the piston rod 15 moves to the extension side and the piston 18 moves to the side of the one side chamber 16, and the pressure in the one side chamber 16 rises relative to the other side chamber 17, the oil flows from the one side chamber 16 to the other side chamber 17 through a fixed orifice, not shown, with a constant flow path area in a region where the piston speed is slow. This generates a damping force having an orifice characteristic. In the region where the piston speed is high, the disc valve 42 moves away from the piston 18 to open the oil passage 45, and the oil flows from one side chamber 16 to the other side chamber 16 with a flow passage area corresponding to the amount of movement away from the piston 18. Thereby, a damping force of the valve characteristic is generated.

When the piston rod 15 moves to the extension side and the amount of protrusion from the cylinder 12 and the outer cylinder 14 increases, the corresponding oil flows from the reservoir chamber 13 to the other side chamber 17 via the oil passage 32 while opening the disc valve 34 of the base valve 23. In contrast, when the piston rod 15 moves to the compression side and the insertion amount into the cylinder 12 and the outer cylinder 14 increases, the corresponding oil liquid opens the disc valve 33 from the other side chamber 17 and flows to the reservoir chamber 13 via the oil passage 31.

As shown in fig. 2, the rod guide 20 has a metal rod guide body 49, and the rod guide body 49 is a substantially stepped cylindrical shape. The rod guide body 49 has a large-diameter outer diameter portion 50 formed on one axial side and a small-diameter outer diameter portion 51 formed on the other axial side and having a smaller diameter than the large-diameter outer diameter portion 50. The rod guide body 49 has an outer shape of a middle-diameter outer diameter portion 52 having an outer diameter in between a large-diameter outer diameter portion 50 and a small-diameter outer diameter portion 51. The rod guide body 49 is fitted to the inner peripheral portion of the cylindrical body part 25 of the outer cylinder 14 at the large-diameter outer diameter portion 50 and fitted to the inner peripheral portion of the cylinder 12 at the small-diameter outer diameter portion 51.

A circular maximum diameter hole portion 53 is formed at the end on the side of the large diameter outer diameter portion 50 in the axial direction at the center in the radial direction of the rod guide body 49. A circular large-diameter hole portion 54 having a smaller diameter than the maximum diameter hole portion 53 is formed in the center of the rod guide body 49 in the radial direction on the side of the small-diameter outer diameter portion 51 in the axial direction than the maximum diameter hole portion 53. Further, a taper hole portion 55 having a smaller diameter as it is farther from the large diameter hole portion 54 is formed on the opposite side of the large diameter hole portion 54 in the axial direction from the maximum diameter hole portion 53. A circular intermediate-diameter hole portion 56 having a slightly smaller diameter than the large-diameter hole portion 54 is formed on the opposite side of the large-diameter hole portion 54 in the axial direction of the taper hole portion 55. Further, a deformed small-diameter hole portion 57 having a minimum diameter smaller than the intermediate-diameter hole portion 56 is formed on the opposite side of the tapered hole portion 55 in the axial direction of the intermediate-diameter hole portion 56. A minimum diameter hole portion 58 having a smaller diameter than the minimum diameter of the small diameter hole portion 57 is formed on the opposite side of the small diameter hole portion 57 from the intermediate diameter hole portion 56 in the axial direction.

As shown in fig. 3, the irregularly shaped small-diameter hole portion 57 is formed with a recess 60 recessed radially outward from a minimum inner diameter portion 59 of the small-diameter hole portion 57 having the smallest inner diameter. The recessed portion 60 is recessed radially outward to the vicinity of the inner peripheral surface of the intermediate diameter hole portion 56. The plurality of recesses 60 are formed at intervals in the circumferential direction of the small-diameter hole portion 57.

As shown in fig. 2, an annular convex portion 61 is formed at an end portion of the rod guide body 49 on the large-diameter outer diameter portion 50 side in the axial direction so as to protrude outward in the axial direction. The maximum diameter hole 53 is formed inside the annular projection 61. The rod guide body 49 has a communication hole 62 formed on the inner diameter side of the annular projection 61 so as to pass through in the axial direction. One end side of the communication hole 62 opens into the maximum diameter hole 53, and the other end side opens into the surface of the large diameter outer diameter portion 50 on the side of the intermediate diameter outer diameter portion 52. The communication hole 62 communicates with the reservoir chamber 13 between the outer cylinder 14 and the cylinder 12.

The rod guide 20 is composed of the rod guide body 49 and a cylindrical collar 63 fitted and fixed to an inner peripheral portion of the rod guide body 49. The collar 63 is formed by coating a fluororesin-impregnated bronze on the inner periphery of a cylindrical body made of metal such as SPCC material or SPCE material. The collar 63 is fitted into the minimum diameter hole portion 58 of the rod guide body 49 by press fitting. The piston rod 15 is inserted through the rod guide 20 so as to be slidably in contact with the collar 63 on the outer peripheral surface 37 of the main shaft portion 38. The rod guide body 49 and the collar 63 are pressed into each other without a gap therebetween and do not pass through the rod guide 20 in the axial direction. In contrast, the collar 63 and the piston rod 15 are slidable therebetween. This provides a communication passage 64 that passes through the rod guide 20 in a minute axial direction.

The seal member 21 is disposed at one end in the axial direction of the outer cylinder 14, and is in pressure contact with the outer peripheral surface 37 of the main shaft 38 of the piston rod 15 at the inner peripheral portion thereof. The seal member 21 restricts leakage of oil or the like leaking from the gap between the rod guide 20 and the main shaft portion 38 of the piston rod 15 to the outside. In fig. 2, the rod guide 20 side of the damper 11 is shown with the piston rod 15 removed. Therefore, the seal member 21 is in a natural state before the piston rod 15 is inserted. The outer peripheral surface 37 of the main shaft portion 38 of the piston rod 15 in the case of insertion is shown by a phantom line (two-dot chain line).

The seal member 21 is constituted by: an oil seal main body 67 of an integral member, which is composed of a seal portion 65 and a ring member 66, the seal portion 65 being composed of an elastic rubber material having good sliding properties such as nitrile rubber or fluororubber, and the ring member 66 being embedded in the seal portion 65 and maintaining the shape of the seal member 21, and being in the shape of a metal ring for securing strength; an annular spring 68 fitted to an outer peripheral portion of the sealing portion 65 of the oil seal main body 67 on the outer side in the cylinder inner-outer direction; and an annular spring 69 fitted to an outer peripheral portion of the seal portion 65 on the inner side in the cylinder inner-outer direction.

The radially inner portion of the seal portion 65 has: an annular cylindrical dust lip 72 extending in a direction away from the annular member 66 in the axial direction from the outside in the cylinder inside-outside direction on the inner peripheral side of the annular member 66; and an annular cylindrical oil lip 73 extending in the axial direction from the inside of the inner circumferential side of the annular member 66 in the cylinder inside-outside direction to a direction away from the annular member 66. The radially outer portion of the seal portion 65 includes an outer peripheral seal 74 covering the outer peripheral surface of the annular member 66 at its outer end position, and an annular seal lip 75 projecting inward in the cylinder inner-outer direction from the outer peripheral seal 74.

The dust lip 72 is formed in a tapered cylindrical shape having an inner diameter that decreases as it goes outward in the cylinder inner-outer direction from the annular member 66 as a whole. An annular groove 78 into which the spring 68 is fitted is formed in the outer peripheral portion of the dust lip 72 so as to be recessed radially inward. Although the example in which the spring 68 is used is shown in the present embodiment, the spring 68 may not be used.

The oil lip 73 has a tapered cylindrical shape having a smaller diameter as a whole is spaced inward in the cylinder inner-outer direction from the annular member 66. An annular groove 79 into which the spring 69 is fitted is formed in an outer peripheral portion of the oil lip 73 so as to be recessed radially inward.

The seal member 21 is in sealing contact with the inner peripheral portion of the cylindrical member 25 of the outer cylinder 14 at the outer peripheral seal 74 in a state where the dust lip 72 is disposed on the outside in the cylinder inside-outside direction, which is the atmosphere side, and the oil lip 73 is disposed on the inside in the cylinder inside-outside direction. In this state, the position of the annular member 66 is clamped and locked by the annular convex portion 61 of the rod guide 20 and the caulked locking portion 28 of the outer cylinder 14. At this time, the seal lip 75 of the seal member 21 is disposed between the annular projection 61 of the rod guide 20 and the outer cylinder 14, and is in sealing contact therewith. The oil lip 73 is disposed with a radial gap in the large-diameter hole portion 54 of the rod guide 20.

In the seal member 21 attached to the outer cylinder 14, the main shaft portion 38 of the piston rod 15 is inserted inside the dust lip 72 and the oil lip 73.

In this state, one end of the piston rod 15 protrudes from one ends of the cylinder 12 and the outer cylinder 14, the dust lip 72 is provided on one end side of the outer cylinder 14 from which the piston rod 15 protrudes, and the oil seal lip 73 is provided on the inner side in the cylinder inner-outer direction than the dust lip 72.

The spring 68 fitted into the annular groove 78 of the dust lip 72 keeps the tightening force of the dust lip 72 in the direction in which the piston rod 15 is brought into close contact in a constant state. In addition, the spring 68 is also used for adjustment of the fastening force in order to meet the design specification. The spring 69 fitted into the annular groove 79 of the oil lip 73 adjusts the tightening force of the oil lip 73 in the direction in which the piston rod 15 is in close contact.

In the above-described seal member 21, the dust lip 72 is brought into close contact with the piston rod 15 by its interference and the binding force generated by the spring 68, thereby maintaining airtightness. Entry of foreign matter adhering to the piston rod 15 when the seal member 21 is externally exposed is mainly restricted by the dust lip 72. In addition, the oil lip 73 is also brought into close contact with the piston rod 15 by its interference and the binding force generated by the spring 69, thereby maintaining airtightness. The oil lip 73 scrapes the oil attached to the piston rod 15 when the piston rod 15 moves in and out, and restricts the oil from leaking to the outside. The oil lip 73 is accumulated in a chamber 85 (low-pressure chamber) formed mainly by the large-diameter hole portion 54 on the inner side in the cylinder inside-outside direction than the seal member 21. That is, the chamber 85 is an oil reservoir for storing oil. The chamber 85 is always in communication with the reservoir chamber 13 via the communication hole 62 of the rod guide 20. Chamber 85 is at the same pressure as reservoir 13.

The friction generating member 22 is fitted into the intermediate diameter hole portion 56 of the rod guide body 49 by press fitting. At this time, the friction generating member 22 abuts against the bottom of the intermediate diameter hole portion 56. The friction generating member 22 is disposed on the inner side in the cylinder inside-outside direction than the seal member 21, that is, on the inner side of the cylinder 12 and the outer cylinder 14. The friction generating member 22 is in pressure contact with an outer peripheral surface 37 of a main shaft portion 38 of the piston rod 15 at an inner peripheral portion thereof. Therefore, the friction generating member 22 generates frictional resistance against the piston rod 15. Fig. 2 and 3 show a state in which the piston rod 15 is removed, and the friction generating member 22 is also in a natural state before the piston rod 15 is inserted. The outer peripheral surface 37 of the main shaft portion 38 of the piston rod 15 in the case of insertion is shown by a phantom line (two-dot chain line).

As shown in fig. 2, the friction generating member 22 is an integral member including an annular elastic rubber portion 91 and an annular base portion 92 made of metal, the annular elastic rubber portion 91 is made of an elastic rubber material such as nitrile rubber or fluororubber, and the base portion 92 is fixed to the elastic rubber portion 91. The friction generating member 22 is fitted in the intermediate diameter hole portion 56 of the rod guide 20 at the base portion 92. The friction generating member 22 is in sliding contact with the outer peripheral surface 37 of the main shaft portion 38 of the piston rod 15 at the elastic rubber portion 91. The base portion 92 maintains the shape of the elastic rubber portion 91, and has strength for fixing the rod guide 20.

With reference to fig. 3, the friction generating member 22 in a natural state will be described. As shown in the one-side cross section of fig. 3, the base portion 92 of the friction generating member 22 has a bottomed cylindrical shape including a flat annular disc portion 101 having a perforated disc shape and a cylindrical fixing portion 102 extending from the outer peripheral side of the annular disc portion 101 in one axial direction. The fixing portion 102 extends in the axial direction with the annular circular plate portion 101 side as a base end, and is formed coaxially with the annular circular plate portion 101. The fixing portion 102 extends only to one axial side from the outer peripheral side of the annular circular plate portion 101. The center axes of the annular circular plate 101 and the fixing portion 102 are aligned, and the fixing portion 102 extends perpendicularly to the annular circular plate 101. The base portion 92 is formed by plastically deforming a flat plate-like material to form a fixing portion 102, or by plastically deforming a cylindrical material to form an annular circular plate portion 101, for example.

The annular disc portion 101 has an inner bottom surface 103 formed of a circular flat surface on the fixing portion 102 side in the axial direction, an inner peripheral surface 104 formed of a cylindrical surface on the opposite side to the fixing portion 102 in the radial direction, and an outer bottom surface 105 formed of a circular flat surface on the opposite side to the fixing portion 102 in the axial direction. An inner circumferential end of the inner bottom surface 103 is connected to one axial end of the inner circumferential surface 104. An inner peripheral end of the outer bottom surface 105 is connected to the other end of the inner peripheral surface 104 in the axial direction.

The fixing portion 102 has an inner peripheral surface 106 formed by a cylindrical surface on the side of the annular circular plate portion 101 in the radial direction, a distal end surface 107 formed by a circular flat surface on the opposite side of the annular circular plate portion 101 in the axial direction, and an outer peripheral surface 108 formed by a cylindrical surface on the opposite side of the annular circular plate portion 101 in the radial direction. The end of the inner circumferential surface 106 on the opposite side to the annular circular plate 101 in the axial direction is continuous with the inner diameter of the distal end surface 107. The end of the outer peripheral surface 108 on the opposite side to the annular circular plate 101 in the axial direction is connected to the outer diameter of the distal end surface 107. The annular circular plate portion 101 has an annular inner R chamfer 109 on the side where the inner bottom surface 103 and the inner peripheral surface 106 are close to each other, and also has an annular outer R chamfer 110 on the side where the outer bottom surface 105 and the outer peripheral surface 108 are close to each other.

The center axes of the inner bottom surface 103, the inner peripheral surface 104, the outer bottom surface 105, the inner peripheral surface 106, the distal end surface 107, the outer peripheral surface 108, the inner R chamfer 109, and the outer R chamfer 110 of the base portion 92 coincide. The inner bottom surface 103, the outer bottom surface 105, and the front end surface 107 are expanded so as to be orthogonal to the central axis. The inner end of the base portion 92 having the smallest diameter is the inner circumferential surface 104 of the annular disc portion 101.

A through hole 111 penetrating from the inner bottom surface 103 side to the outer bottom surface 105 side of the inner R-chamfer 109 is formed in the annular circular plate portion 101 of the base portion 92. The through hole 111 is parallel to the central axis of the annular disc portion 101 and the fixing portion 102, that is, the central axis of the base portion 92, and parallel to the central axis of the friction generating member 22. The plurality of through holes 111 are formed at equal intervals in the circumferential direction of the annular circular plate portion 101.

The elastic rubber portion 91 has an annular shape with a central axis aligned with the base portion 92. The elastic rubber portion 91 has: a body portion 121 disposed radially inward of the fixing portion 102 of the base portion 92, and formed on the fixing portion 102 side of the annular circular plate portion 101 in the axial direction; and an inner covering portion 122 formed on the inner circumferential side of the annular circular plate portion 101 so as to protrude outward in the axial direction from the end portion of the inner circumferential portion of the body portion 121 on the annular circular plate portion 101 side in the axial direction.

The outer peripheral portion 127 of the body portion 121 having the outer peripheral surface 126 is entirely spaced radially inward from the inner peripheral surface 106 of the fixing portion 102 of the base portion 92. The body portion 121 is located radially inward of the through hole 111 of the annular disc portion 101 of the base portion 92. The body portion 121 is fixed to the inner bottom surface 103 of the annular disc portion 101 of the base portion 92 by a base end fixing surface 128 connected to one side of the outer peripheral surface 126 in the axial direction. The outer peripheral surface 126 is tapered such that the diameter increases toward the base end side fastening surface 128 in the axial direction. The outer peripheral surface 126 is exposed without being fixed to the base portion 92. Therefore, the elastic rubber portion 91 is overlapped with the inner peripheral side of the cylindrical fixing portion 102 in the axial direction and is provided to be separated in the radial direction as a whole.

The inner cover portion 122 is fixed to the inner peripheral surface 104 of the annular disc portion 101 of the base portion 92 by an inner peripheral fixing surface 129, and the inner peripheral fixing surface 129 is connected to the base end fixing surface 128 on the side opposite to the outer peripheral surface 126. The elastic rubber portion 91 is fixed to the base portion 92 over the entire surface of the portion in contact with the base portion 92. The elastic rubber portion 91 is fixed to the base portion 92 only by the annular circular plate portion 101.

The elastic rubber portion 91 has a tip end portion 135 including a tip end surface 134 exposed in a direction axially opposite to the base end side fastening surface 128 of the body portion 121 without being fastened to the base portion 92.

The inner peripheral portion 136 of the elastic rubber portion 91 is not fixedly exposed to the base portion 92. The inner peripheral portion 136 of the elastic rubber portion 91 has: a minimum inner diameter portion 137 having a minimum diameter in the elastic rubber portion 91 and also in the friction generating member 22; a distal end side tapered portion 139 having a tapered inner peripheral surface 138 that expands and expands so as to become larger in diameter as the distance from the minimum inner diameter portion 137 to the distal end surface 134 side in the axial direction increases; a tapered base end side tapered portion 141 having a tapered inner peripheral surface 140 that expands and expands so as to become larger in diameter as it becomes farther from the minimum inner diameter portion 137 toward the opposite side of the distal end surface 134 in the axial direction from the minimum inner diameter portion 137.

The minimum inner diameter portion 137, the distal end side tapered portion 139, and the base end side tapered portion 141 are formed in the body portion 121.

The inner peripheral portion 136 of the elastic rubber portion 91 has: a fixed diameter portion 143 having a cylindrical planar inner peripheral surface 142 connected to the opposite side of the smallest inner diameter portion 137 of the inner peripheral surface 140; and a tapered portion 145 having a tapered inner peripheral surface 144 located on the opposite side of the inner peripheral surface 142 from the inner peripheral surface 140 and having a diameter that increases as the distance from the inner peripheral surface 142 increases. The inner peripheral surface 144 is continuous with the outer bottom surface 105 of the annular disc portion 101. The fixed diameter portion 143 and the tapered portion 145 are formed on the inner cover portion 122.

In other words, the elastic rubber portion 91 is provided with a minimum inner diameter portion 137, a distal end side tapered portion 139 and a proximal end side tapered portion 141 on both sides of the minimum inner diameter portion 137 in the axial direction, a sizing portion 143, and a tapered portion 145, on the inner circumferential side, and the boundary portion between the distal end side tapered portion 139 and the proximal end side tapered portion 141 is the minimum inner diameter portion 137. The distal tapered portion 139 and the base tapered portion 141 are arranged on the side of the base portion 92 away from the annular circular plate portion 101 and the base tapered portion 141 is arranged on the side closer to the annular circular plate portion 101 in the axial direction of the elastic rubber portion 91. In other words, the elastic rubber portion 91 is provided with a minimum inner diameter portion 137 on the inner circumferential side, a distal-side tapered portion 139 that expands in diameter from the minimum inner diameter portion 137 toward the side opposite to the one-side chamber 16 in the axial direction, and a proximal-side tapered portion 141 that expands in diameter from the minimum inner diameter portion 137 toward the one-side chamber 16 in the axial direction.

The minimum inner diameter portion 137, the distal end side tapered portion 139, the proximal end side tapered portion 141, the sizing portion 143, and the tapered portion 145 are annular portions that are continuous over the entire circumference of the elastic rubber portion 91 in the circumferential direction. Since the center axis of the elastic rubber portion 91 is made to coincide with the base portion 92, the center axes of the outer peripheral surface 126, the front end surface 134, the inner peripheral surface 138, the minimum inner diameter portion 137, the inner peripheral surface 140, the inner peripheral surface 142, and the inner peripheral surface 144 coincide with the base portion 92.

As shown in fig. 2, the friction generating member 22 having the above-described structure is fitted and fixed by press fitting from the large diameter hole 54 side of the rod guide 20 to the middle diameter hole 56, which is a target portion to be fixed, in a state where the annular circular plate portion 101 of the base portion 92 is positioned further inward in the cylinder inside-outside direction than the fixing portion 102. At this time, as shown in fig. 3, the fixing portion 102 of the base portion 92 of the friction generating member 22 is fitted to the inner peripheral surface of the intermediate diameter hole 56 at the outer peripheral surface 108, and the annular circular plate portion 101 abuts against the bottom surface of the bottom portion of the intermediate diameter hole 56 at the outer bottom surface 105. At this time, the through hole 11 communicates with the circumferential position of the rod guide body 49 in alignment with the recess 60. The base portion 92 has a tubular fixing portion 102 for fixing the friction generating member 22 to the intermediate diameter hole portion 56 of the rod guide 20 as a target portion.

In the inner peripheral portion 136 of the elastic rubber portion 91, the distal-side tapered portion 139 is disposed on the cylinder inside-outside direction outer side of the minimum inner diameter portion 137, and the proximal-side tapered portion 141 is disposed on the cylinder inside-outside direction inner side of the minimum inner diameter portion 137.

The minimum inner diameter portion 137 of the friction generating member 22 has an inner diameter smaller than the outer diameter of the main shaft portion 38 of the piston rod 15, that is, the diameter of the outer circumferential surface 37. Therefore, the main shaft portion 38 of the piston rod 15 is inserted into the elastic rubber portion 91 of the friction generating member 22 with a predetermined interference. As a result, the friction generating member 22 is elastically deformed radially outward by the elastic rubber portion 91 and is in close contact with the main shaft portion 38 of the piston rod 15 over the entire circumference.

In the state of being fitted to the piston rod 15 in this way, the minimum inner diameter portion 137 of the elastic rubber portion 91, a portion of the distal end side tapered portion 139 on the minimum inner diameter portion 137 side, and a portion of the proximal end side tapered portion 141 on the minimum inner diameter portion 137 side are lips 155 that slide in contact with the main shaft portion 38 of the piston rod 15. In other words, the elastic rubber portion 91 is formed with a lip portion 155 that is in sliding contact with the piston rod 15.

The friction generating member 22 fitted to the piston rod 15, the bottom of the small-diameter hole 57 of the rod guide body 49, the plurality of recesses 60, and the collar 63 form a chamber 151. At this time, the inner peripheral surface 140 of the base end side tapered portion 141, the inner peripheral surface 142 of the sizing portion 143, the inner peripheral surface 144 of the tapered portion 145, and the outer bottom surface 105 of the annular circular plate portion 101 of the friction generating member 22 form a chamber 151. The remaining part of the base end side tapered portion 141 of the elastic rubber portion 91 on the side opposite to the minimum inner diameter portion 137, where the lip portion 155 is not formed, serves as a pressure receiving portion 156 that receives the pressure of the chamber 151 and the one side chamber 16 communicating with the chamber 151 via the communication passage 64 in the radial direction. Therefore, a lip portion 155 is formed on the sealing member 21 side on the inner peripheral side of the elastic rubber portion 91, and a pressure receiving portion 156 that receives the pressure of the one-side chamber 16 is formed on the one-side chamber 16 side.

The inner peripheral surface 138 of the distal end side tapered portion 139 of the elastic rubber portion 91 of the friction generating member 22 in the state of being fitted to the piston rod 15, the distal end surface 134 of the distal end portion 135, and the outer peripheral surface 126 of the outer peripheral portion 127, the inner peripheral surface 106 of the fixing portion 102, the distal end surface 107, and a part of the distal end surface 107 side of the outer peripheral surface 108 form the chamber 85.

The chamber 151 communicates with the one-side chamber 16 via a communication passage 64 between the collar 63 and the piston rod 15. The chamber 151 communicates with the chamber 85 and the reservoir chamber 13 via a communication passage 152 in the through hole 111 of the friction generating member 22. The flow passage cross-sectional area of the communication passage 152 is narrower than the flow passage cross-sectional area of the communication passage 64. Therefore, the pressure loss due to the communication passage 152 is higher than the pressure loss due to the communication passage 64. The communication passage 152 always communicates the chamber 85 with the first chamber 16 and the chamber 151, and therefore the hydraulic fluid in the first chamber 16 is supplied to the chamber 85. This prevents the communication path 152 from sticking due to poor lubrication of the seal member 21. The communication passage 152 discharges air mixed in the one chamber 16.

In the shock absorber 11, when the piston rod 15 moves to the extension side extending the entire length of the shock absorber 11 and the piston 18 moves to the one chamber 16 side to increase the pressure of the one chamber 16, the pressure of the chamber 151 also increases via the communication passage 64. However, the pressure in the chamber 85 may be delayed from increasing through the communication passage 152 having a high pressure loss. At this time, in the flow direction of the oil, the upstream side of the elastic rubber portion 91 is the chamber 151, and the downstream side is the chamber 85. Further, the chamber 85 between the downstream side of the elastic rubber portion 91 and the reservoir chamber 13 has an internal pressure lower than the internal pressures of the one chamber 16 and the chamber 151. The relationship between the communication passage 152 and the communication passage 64 is set so that the communication passage 152 > the communication passage 64. The communication path 152 is not necessarily required.

The elastic rubber portion 91 receives a force radially outward mainly at the pressure receiving portion 156 of the base end side tapered portion 141 due to the pressure difference between the one side chambers 16 and 151 and the chambers 85 and the reservoir chamber 13 generated in this manner. When the pressure difference between the one-side chamber 16 and the chamber 151, and the chamber 85 and the reservoir chamber 13 reaches a predetermined pressure, the elastic rubber portion 91 deforms radially outward under the pressure received by the pressure receiving portion 156 of the base-end-side tapered portion 141, and a radial gap is formed between the elastic rubber portion and the piston rod 15, thereby allowing the upstream-side chamber 151 and the downstream-side chamber 85 to communicate with each other through the gap. That is, the elastic rubber portion 91 is formed so as to be able to communicate the upstream chamber 151 with the downstream chamber 85 when the pressure difference between the one chamber 16 and the reservoir chamber 13 reaches a predetermined pressure.

As described above, in the shock absorber 11 of the first embodiment described above, when the piston rod 15 moves to the extension side, the damping force based on the orifice characteristic of the fixed orifice, not shown, is generated in the region where the piston speed is low, and the disc valve 42 is separated from the piston 18 in the region where the piston speed is high, thereby generating the damping force of the valve characteristic. When the piston rod 15 moves to the compression side, a damping force based on the orifice characteristic of the fixed orifice, not shown, is generated in a region where the piston speed is low, and a damping force based on the valve characteristic is generated by separating the disc valve 41 from the piston 18 in a region where the piston speed is high.

Here, in the extremely low speed region where the piston speed is slower than the hydraulic damping region where the hydraulic damping force is generated by the fixed orifice and the disc valves 41 and 42, which are not shown, the damping force by the fixed orifice and the disc valves 41 and 42, which are not shown, is hardly generated. Therefore, the frictional resistance against the piston rod 15 by the seal member 21 and the friction generating member 22 and the frictional resistance against the cylinder 12 by the piston 18 become main generation sources of the damping force.

Patent document 1 describes a hydraulic shock absorber in which a friction generating member that slides in contact with a piston rod is provided, and communication passages that communicate with both sides of the friction generating member in the axial direction are provided. Since this hydraulic shock absorber is provided with the communication passage that communicates both axial sides of the friction generating member, both axial sides of the friction generating member maintain substantially the same pressure.

However, in the shock absorber, the hydraulic damping force is not generated in a micro-amplitude region where the amplitudes of the piston rod and the piston are extremely small, and the frictional force by the friction generating member is generated, and it is desired to suppress the generation of the frictional force in a normal region (the hydraulic damping region described above) where the amplitudes of the piston rod and the piston are larger than the micro-amplitude region. This is because, in a normal region, in a shock absorber in which a frictional force generated by a friction generating member is large, the shock absorber may impair ride comfort of a vehicle used for a suspension apparatus. By generating an axial force (hereinafter referred to as a sliding force) by a sliding resistance by the friction generating member, it is possible to compensate for a damper axial force in a region where the piston speed is slightly low, which is insufficient in a normal shock absorber, and to improve the riding comfort and the steering stability. However, since the sliding force of the friction generating member is generated in the same manner regardless of the piston speed of the shock absorber in the region other than the very low speed region, the stroke feeling and the like of the shock absorber may be reduced, and the riding comfort may be impaired.

In the shock absorber 11 of the first embodiment, in the micro-amplitude region of the piston rod 15 and the piston 18 in which the hydraulic damping force is not generated, the pressure in the one-side chamber 16 and the pressure in the reservoir chamber 13 are substantially equal, and therefore the lip portion 155 of the elastic rubber portion 91 of the friction generating member 22 is in contact with the main shaft portion 38 of the piston rod 15 in a tightly attached state. Therefore, the sliding resistance to the piston rod 15 generated by the friction generating member 22 is high.

On the other hand, in the extension stroke and the compression stroke in the normal region (the hydraulic damping region described above) in which the amplitude is larger than the micro-amplitude region, the piston speed becomes higher, the pressure of the one side chamber 16 becomes higher than the pressure of the reservoir chamber 13, and the pressure of the chamber 151 communicating with the one side chamber 16 via the communication passage 64 also becomes higher. On the other hand, the pressure of the chamber 85 communicating with the chamber 151 via the communication passage 152 having a high pressure loss does not increase, and the chamber 85 has an internal pressure lower than the internal pressures of the one chamber 16 and the chamber 151. At this time, the chamber 85 between the downstream side of the elastic rubber portion 91 and the reservoir chamber 13 becomes a low pressure chamber having an internal pressure lower than the internal pressure of the one chamber 16.

The elastic rubber portion 91 receives the pressure of the one-side chamber 16 and the chamber 151, which is higher than the pressure of the chamber 85 and the reservoir chamber 13, at the pressure receiving portion 156 on the one-side chamber 16 side than the lip portion 155 in sliding contact with the piston rod 15, and deforms radially outward, so that the tightening force to the main shaft portion 38 of the piston rod 15 decreases, and the sliding resistance decreases. In other words, the elastic rubber portion 91 receives a force outward in the radial direction due to the pressure difference between the one side chamber 16 and the chamber 151, and the chamber 85 and the reservoir chamber 13, so that the tightening force to the main shaft portion 38 of the piston rod 15 is reduced, and the sliding resistance is reduced.

When the piston speed is further increased and the pressure difference between the one side chamber 16 and the chamber 151, and between the chamber 85 and the reservoir chamber 13 reaches a predetermined pressure, the elastic rubber portion 91 is separated in the radial direction from the main shaft portion 38 of the piston rod 15, and the upstream side chamber 16 and the chamber 151, and the downstream side chamber 85 and the reservoir chamber 13 communicate with each other in the flow direction of the hydraulic fluid. At this time, the sliding resistance of the piston rod 15 disappears.

As described above, the friction generating member 22 generates a sliding force corresponding to the piston speed with respect to the piston rod 15, thereby obtaining a good operating characteristic and suppressing a decrease in the ride comfort performance of the vehicle using the shock absorber 11 due to an excessive sliding force.

That is, in order to obtain good ride comfort and steering stability, the shock absorber 11 can apply an appropriate sliding force to the piston rod 15 by the friction generating member 22 in a region where the piston speed is at a very low speed in which an axial force (hereinafter, referred to as a hydraulic pressure) based on a pressure loss caused by the working fluid is hardly generated. On the other hand, in a region where the piston speed becomes high and the hydraulic pressure is generated (the hydraulic damping region described above), the sliding force of the friction generating member 22 with respect to the piston rod 15 can be suppressed to be low. Thus, the damper 11 can generate a required sliding force in the very low speed region and reduce the sliding force in the oil pressure generating region. In other words, the required sliding force can be generated in the very low speed region, and the sliding force can be reduced in the oil pressure generating region. This can provide excellent operating characteristics and suppress a reduction in the ride comfort performance of the vehicle using the shock absorber 11.

Further, as described above, since the chamber 85 between the downstream side of the elastic rubber portion 91 and the reservoir chamber 13 is a low pressure chamber having an internal pressure lower than the internal pressure of the one chamber 16, the above-described pressure difference can be favorably generated in the elastic rubber portion 91.

Further, since the chamber 85 communicates with the reservoir chamber 13, the chamber 85 can be maintained at a low pressure, and the elastic rubber portion 91 can favorably generate the above-described pressure difference.

Further, since the lip portion 155 which is in sliding contact with the piston rod 15 is formed in the elastic rubber portion 91, a frictional force can be generated satisfactorily when the frictional force is generated.

Further, a lip portion 155 that slides in contact with the piston rod 15 is formed on the sealing member 21 side in the axial direction on the inner peripheral side of the elastic rubber portion 91. A pressure receiving portion 156 that receives the pressure of the one chamber 16 via the chamber 151 is formed on the one chamber 16 side in the axial direction on the inner peripheral side of the elastic rubber portion 91. Therefore, the elastic rubber portion 91 can be made compact.

[ second embodiment ]

Next, a second embodiment of the present invention will be described mainly focusing on differences from the first embodiment with reference to fig. 4 and 5. Parts common to those of the first embodiment are denoted by the same reference numerals and the same names.

In the damper 11A of the second embodiment, a friction generating member 22A is provided in place of the friction generating member 22 of the first embodiment, and a rod guide 20A is provided in place of the rod guide 20 of the first embodiment, the rod guide 20A having a rod guide body 49A partially different from the rod guide body 49. Fig. 4 and 5 also show the friction generating member 22A in a natural state before the piston rod 15 is inserted, and the outer peripheral surface 37 of the main shaft portion 38 of the piston rod 15 in the case of insertion is shown by a virtual line (two-dot chain line).

The friction generating member 22 is provided on the inner side in the cylinder inside-outside direction than the seal member 21 between the seal member 21 and the rod guide 20A. The friction generating member 22A is annular, and the piston rod 15 is slidably inserted therein. The friction generating member 22A is fitted and fixed to the rod guide 20A at its outer peripheral portion. The inner peripheral portion of the friction generating member 22A is in sliding contact with the outer peripheral portion of the piston rod 15, and generates frictional resistance in the piston rod 15. The friction generating member 22A is provided at a position on the side of the cylinder 12 defined by the seal member 21, not for the purpose of sealing.

The rod guide body 49A has a small-diameter hole portion 57A partially different from the small-diameter hole portion 57 of the first embodiment. The small-diameter hole portion 57A is formed without the recess 60 and has a circular shape with a smaller diameter than the middle-diameter hole portion 56 and a larger diameter than the minimum-diameter hole portion 58.

The friction generating member 22A is fitted into the intermediate diameter hole portion 56 of the rod guide body 49A of the rod guide 20A by press fitting. At this time, the friction generating member 22A abuts against the bottom surface of the bottom of the intermediate diameter hole portion 56. The friction generating member 22A is disposed further inward in the cylinder inside-outside direction than the seal member 21. The inner peripheral portion of the friction generating member 22A is in pressure contact with the outer peripheral surface 37 of the main shaft portion 38 of the piston rod 15, and generates frictional resistance against the piston rod 15.

As shown in fig. 5, the friction generating member 22A is an integral member including an annular elastic rubber portion 91A and an annular base portion 92A made of metal, the annular elastic rubber portion 91A being made of an elastic rubber material such as nitrile rubber or fluororubber, and the base portion 92A being fixed to the elastic rubber portion 91A. The friction generating member 22A is fitted in the intermediate diameter hole portion 56 of the rod guide 20A at the base portion 92A. The friction generating member 22A is in sliding contact with the outer peripheral surface 37 of the main shaft portion 38 of the piston rod 15 at the elastic rubber portion 91A. The base portion 92A maintains the shape of the elastic rubber portion 91A, and obtains strength for fixing the rod guide 20A.

With reference to fig. 5, the friction generating member 22A in a natural state will be described. The base portion 92A of the friction generating member 22A has a bottomed, covered cylindrical shape including a flat perforated disc-shaped annular disc portion 200, a cylindrical fixing portion 201 extending from the outer peripheral side of the annular disc portion 200 toward one axial side, and a flat perforated disc-shaped annular disc portion 202 extending radially inward from the fixing portion 201 in the axial direction on the side opposite to the annular disc portion 200.

The fixing portion 201 extends in the axial direction between the annular circular plate portions 200 and 202. The fixing portion 201 is formed coaxially with the annular circular plate portions 200 and 202. The center axes of the annular circular plate portions 200 and 202 and the fixing portion 201 are aligned. The annular circular plate portions 200 and 202 are parallel to each other, and the fixing portion 201 is perpendicular to them. The base portion 92A is formed by plastically deforming a cylindrical material into annular disc portions 200 and 202, for example.

The annular disc portion 200 includes: an inner bottom surface 203 formed by a circular flat surface on the fixing portion 201 side in the axial direction, an inner peripheral surface 204 formed by a cylindrical surface on the opposite side of the fixing portion 201 in the radial direction, and an outer bottom surface 205 formed by a circular flat surface on the opposite side of the fixing portion 201 in the axial direction. An inner peripheral end of the inner bottom surface 203 is connected to one axial end of the inner circumferential surface 204, and an inner peripheral end of the outer bottom surface 205 is connected to the other axial end of the inner circumferential surface 204.

The fixing portion 201 includes: an inner circumferential surface 206 formed by a cylindrical surface on the side of the annular disc portion 200 in the radial direction, and an outer circumferential surface 208 formed by a cylindrical surface on the opposite side of the annular disc portion 200 in the radial direction. The annular circular plate portion 200 has an annular inner R chamfer 209 connecting the inner bottom surface 203 and the inner peripheral surface 206 on the side close to each other, and also has an annular outer R chamfer 210 connecting the outer bottom surface 205 and the outer peripheral surface 208 on the side close to each other. In the present embodiment, the R chamfer 210 is provided, but the R chamfer 210 may not be provided.

The annular circular plate portion 202 has: an inner bottom surface 213 formed by a circular flat surface on the fixing portion 201 side in the axial direction, an inner peripheral surface 214 formed by a cylindrical surface on the opposite side to the fixing portion 201 in the radial direction, and an outer bottom surface 215 formed by a circular flat surface on the opposite side to the fixing portion 201 in the axial direction. An inner peripheral end of the inner bottom surface 213 is connected to one axial end of the inner peripheral surface 214, and an inner peripheral end of the outer bottom surface 215 is connected to the other axial end of the inner peripheral surface 214.

The annular circular plate portion 202 has an annular inner R chamfer 219 connecting the inner bottom surface 213 and the inner peripheral surface 206 on the side close to each other, and also has an annular outer R chamfer 220 connecting the outer bottom surface 215 and the outer peripheral surface 208 on the side close to each other.

The center axes of inner bottom surfaces 203, 213, inner peripheral surfaces 204, 214, outer bottom surfaces 205, 215, inner peripheral surface 206, outer peripheral surface 208, inner R chamfers 209, 219, and outer R chamfers 210, 220 of base portion 92A coincide with each other. The inner bottom surfaces 203, 213 and the outer bottom surfaces 205, 215 are expanded in a manner orthogonal to the central axis. The inner peripheral surface 204 has the smallest diameter also in the annular circular plate portion 200, and the inner peripheral surface 214 has the smallest diameter also in the annular circular plate portion 202. The inner diameter of the inner peripheral surface 214 of the annular disc portion 202 of the base portion 92A is larger than the inner diameter of the inner peripheral surface 204 of the annular disc portion 200. Therefore, the inner peripheral surface 204 has the smallest diameter at the base portion 92A.

The annular circular plate portion 200 of the base portion 92A is formed with a through hole 221 penetrating from the inner bottom surface 203 to the outer bottom surface 205. The through hole 221 is parallel to the central axis of the annular disk portions 200 and 202 and the fixing portion 202, that is, the central axis of the base portion 92, and parallel to the central axis of the friction generating member 22A. The plurality of through holes 221 are formed at equal intervals in the circumferential direction of the annular disk portion 200. In the present embodiment, a plurality of through holes 221 are provided, but one through hole may be provided.

The fixing portion 201 of the base portion 92A is formed with a through hole 222 penetrating from the inner peripheral surface 206 to the outer peripheral surface 208. The through hole 222 is formed on the annular disk portion 202 side of the fixing portion 201 in the axial direction and extends in the radial direction of the fixing portion 201. The through holes 222 are formed in the fixing portion 201 at equal intervals in the circumferential direction.

The elastic rubber portion 91A has an annular shape with a central axis aligned with the base portion 92A. The elastic rubber portion 91A includes: a body portion 121A disposed radially inward of the fixing portion 201 of the base portion 92A and formed on the fixing portion 201 side of the annular circular plate portion 202 in the axial direction; an inner covering portion 122A formed on the inner circumferential side of the annular circular plate portion 202 so as to protrude outward in the axial direction from the end portion on the annular circular plate portion 202 side in the axial direction of the inner circumferential portion of the body portion 121A; and a front end lip portion 224 protruding from the body portion 121A to the opposite side of the inner covering portion 122A in the axial direction.

An outer peripheral portion 227 having an outer peripheral surface 226 of the body portion 121A is entirely spaced radially inward from the inner peripheral surface 206 of the fixing portion 201 of the base portion 92A. The body portion 121A is fixed to the inner bottom surface 213 of the annular disc portion 202 of the base portion 92A by a base end fixing surface 228 continuous with one side of the outer peripheral surface 226 in the axial direction. The outer peripheral surface 226 is tapered such that the diameter increases toward the base end side fastening surface 228 in the axial direction. The outer peripheral surface 226 is not fixedly exposed to the base portion 92A. Therefore, the elastic rubber portion 91A is overlapped with the inner peripheral side of the cylindrical fixing portion 201 in the axial direction and is provided to be separated in the radial direction as a whole.

The inner cover portion 122A is fixed to the inner peripheral surface 214 of the annular disc portion 202 by an inner peripheral fixing surface 229, and the inner peripheral fixing surface 229 is connected to the base end fixing surface 228 on the side opposite to the outer peripheral surface 226. The elastic rubber portion 91A is fixed to the base portion 92A over the entire surface of the portion in contact with the annular circular plate portion 202. The elastic rubber portion 91A is fixed to the base portion 92A only by the annular circular plate portion 202.

The elastic rubber portion 91A has a distal end portion 235 including a distal end surface 234 exposed without being fixedly secured to the base portion 92A in a direction axially opposite to the proximal end side securing surface 228 of the body portion 121A. The distal end portion 235 is located on the annular circular plate portion 202 side in the axial direction with respect to the annular circular plate portion 200, and the distal end surface 234 faces the inner bottom surface 203.

The elastic rubber portion 91A has a tip lip portion 224 on a side opposite to the outer peripheral surface 226 in the radial direction from the tip end surface 234 of the tip portion 235. The distal end lip portion 224 extends further toward the annular disk portion 200 side in the axial direction than the distal end face 234 and abuts on the inner side in the radial direction than the through hole 221 of the inner bottom face 203 of the annular disk portion 200. The distal end lip portion 224 is annular and abuts against the inner bottom surface 203 over the entire circumference of the elastic rubber portion 91A in the circumferential direction. The distal end lip portion 224 has a shape in which the diameter decreases toward the extended distal end side. The thickness in the radial direction becomes thinner as the leading end lip 224 extends closer to the leading end side.

The inner peripheral portion 236 of the elastic rubber portion 91A is not fixedly exposed to the base portion 92A. The inner peripheral portion 236 of the elastic rubber portion 91A has the smallest diameter in the elastic rubber portion 91A. The inner peripheral portion 236 of the elastic rubber portion 91A has: a minimum inner diameter portion 237 which is also the smallest diameter in the friction generating member 22A; a distal end side tapered portion 239 having a tapered inner peripheral surface 238 that expands and expands in diameter so as to become larger in diameter as the distance from the minimum inner diameter portion 237 increases from the minimum inner diameter portion 237 toward the distal end surface 234 side in the axial direction; a tapered base end side tapered portion 241 having a tapered inner peripheral surface 240 that expands and expands in diameter so as to become farther from the minimum inner diameter portion 237 toward the opposite side of the distal end surface 234 in the axial direction from the minimum inner diameter portion 237. The minimum inner diameter portion 237, the distal end side tapered portion 239, and the proximal end side tapered portion 241 are formed in the body portion 121A. A tip lip portion 224 is provided between the tip-side tapered portion 239 and the tip portion 235.

Further, the inner peripheral portion 236 of the elastic rubber portion 91A has: a fixed diameter portion 243 having a cylindrical planar inner peripheral surface 242 continuous to the opposite side of the smallest inner diameter portion 237 of the inner peripheral surface 240; a tapered portion 245 having a tapered inner peripheral surface 244 located on the opposite side of the inner peripheral surface 242 from the inner peripheral surface 240 and having a diameter that increases as the distance from the inner peripheral surface 242 increases. The inner peripheral surface 244 is continuous with the outer bottom surface 215 of the annular disc portion 202.

In other words, the elastic rubber portion 91A is provided with the minimum inner diameter portion 237, the distal end side tapered portion 239, the base end side tapered portion 241, the sizing portion 243, and the tapered portion 245 on both axial sides of the minimum inner diameter portion 237, on the inner circumferential side. The boundary between the distal end tapered portion 239 and the base end tapered portion 241 is the minimum inner diameter portion 237. In the distal tapered portion 239 and the base tapered portion 241, the distal tapered portion 239 is disposed on the side away from the annular circular plate portion 202 of the base portion 92A, the base tapered portion 241 is disposed on the side closer to the annular circular plate portion 202, the distal tapered portion 239 is disposed on the side closer to the annular circular plate portion 200 of the base portion 92A, and the base tapered portion 241 is disposed on the side away from the annular circular plate portion 200 in the axial direction of the elastic rubber portion 91. In other words, the elastic rubber portion 91A is provided with a minimum inner diameter portion 237, a distal-side tapered portion 239 which expands and expands from the minimum inner diameter portion 237 toward the one side chamber 16 in the axial direction, and a proximal-side tapered portion 241 which expands and expands from the minimum inner diameter portion 237 toward the opposite side of the one side chamber 16 in the axial direction.

The minimum inner diameter portion 237, the distal end side tapered portion 239, the proximal end side tapered portion 241, the sizing portion 243, and the tapered portion 245 are each annular and continuous over the entire circumference of the elastic rubber portion 91A in the circumferential direction. Since the center axis of the elastic rubber portion 91A coincides with the base portion 92A, the center axes of the outer peripheral surface 226, the front end surface 234, the inner peripheral surface 238, the minimum inner diameter portion 237, the inner peripheral surface 240, the inner peripheral surface 242, the inner peripheral surface 244, and the front end lip portion 224 coincide with the base portion 92A.

As shown in fig. 4, the friction generating member 22A having the above-described structure is fitted and fixed to the intermediate diameter hole 56, which is a target portion to be fixed, by press-fitting from the side of the large diameter hole 54 of the rod guide 20 in a posture in which the annular circular plate portion 200 of the base portion 92A is positioned on the inner side in the cylinder inside-outside direction and the annular circular plate portion 202 is positioned on the outer side in the cylinder inside-outside direction. At this time, as shown in fig. 5, the fixing portion 201 of the base portion 92A of the friction generating member 22A is fitted to the inner peripheral surface of the intermediate diameter hole 56 at the outer peripheral surface 208. The annular circular plate portion 200 of the friction generating member 22A abuts against the bottom surface of the bottom of the intermediate diameter hole portion 56 at the outer bottom surface 205. In this state, the through hole 221 of the annular disc portion 200 is located radially inward of the inner peripheral surface of the small-diameter hole portion 57A. The through hole 221 of the annular disc portion 200 opens into the small-diameter hole portion 57A. Further, the through hole 222 of the fixing portion 201 opens into the taper hole portion 55.

On the inner peripheral side of the elastic rubber portion 91A, the distal end side tapered portion 239 is disposed on the inner side in the cylinder inner/outer direction than the minimum inner diameter portion 237, and the base end side tapered portion 241 is disposed on the outer side in the cylinder inner/outer direction than the minimum inner diameter portion 237. The base portion 92A has a tubular fixing portion 201 for fixing the friction generating member 22A to the intermediate diameter hole portion 56 of the rod guide 20 as a target portion.

The main shaft portion 38 of the piston rod 15 is inserted inside the elastic rubber portion 91A of the friction generating member 22A with a predetermined interference. Therefore, the elastic rubber portion 91A is elastically deformed outward in the radial direction and is in close contact with the main shaft portion 38 of the piston rod 15 over the entire circumference.

In the state of being fitted to the piston rod 15 in this way, the minimum inner diameter portion 237 of the elastic rubber portion 91A, a portion of the distal end side tapered portion 239 on the minimum inner diameter portion 237 side, and a portion of the proximal end side tapered portion 241 on the minimum inner diameter portion 237 side form a lip portion 255 that is in sliding contact with the main shaft portion 38 of the piston rod 15.

The friction generating member 22A fitted to the piston rod 15, the small-diameter hole 57A of the rod guide body 49, and the collar 63 form a chamber 151A communicating with the communication passage 64. At this time, the inner peripheral surface 238 of the distal-end-side tapered portion 239, the distal end lip portion 224, the inner peripheral surface 204 of the annular disc portion 200, and the outer bottom surface 205 of the friction generating member 22A form the chamber 151A. The remaining part of the distal-end-side tapered portion 239 of the elastic rubber portion 91A on the side opposite to the minimum inner diameter portion 237, where the lip portion 255 is not formed, serves as a pressure receiving portion 256 that receives the pressure of the chamber 151A and the one-side chamber 16 communicating with the chamber 151A via the communication passage 64 in the radial direction. Therefore, a lip 255 is formed on the sealing member 21 side in the axial direction on the inner peripheral side of the elastic rubber portion 91A, and a pressure receiving portion 256 that receives the pressure of the one-side chamber 16 is formed on the one-side chamber 16 side in the axial direction.

The inner peripheral surface 240 of the base end side tapered portion 241, the inner peripheral surface 242 of the sizing portion 243, the inner peripheral surface 244 of the tapered portion 245, the outer bottom surface 215 of the annular circular plate portion 202, the outer R chamfer 220, and a portion of the outer R chamfer 220 side of the outer peripheral surface 208 of the elastic rubber portion 91A in the friction generating member 22A in a state of being fitted to the piston rod 15 form the oil reservoir chamber 85A. The oil lip 73 of the seal member 21 scrapes the oil adhering to the piston rod 15 when the piston rod 15 enters to the outside, and accumulates in the oil reservoir 85A. The oil reservoir chamber 85A is always in communication with the reservoir chamber 13 via the communication hole 62, and has the same pressure as the reservoir chamber 13.

The front end lip 224 of the friction generating member 22A in a state of being fitted to the piston rod 15, the outer peripheral surface 226 of the front end face 234 and the outer peripheral portion 227 of the front end portion 235, the inner bottom surface 203 of the annular disc portion 200, the inner R chamfer 209, the inner peripheral surface 206 of the fixing portion 201, and the inner R chamfer 219 of the annular disc portion 202 form an inner chamber 261 (low pressure chamber). The inner chamber 261 is always in communication with the oil reservoir chamber 85A and the reservoir chamber 13 via the communication passage 253 in the through hole 222, and has the same pressure as the reservoir chamber 13.

The chamber 151A communicates with a communication passage 64 between the collar 63 and the piston rod 15. The chamber 151A communicates with the inner chamber 261 via a communication path 252 in the through hole 221 of the friction generating member 22A. The flow passage cross-sectional area of the communication passage 252 is narrower than the flow passage cross-sectional area of the communication passage 64. Therefore, the pressure loss due to the communication passage 252 is higher than the pressure loss due to the communication passage 64. The communication passage 253 communicating the inner chamber 261 and the oil reservoir 85A has a wider flow passage cross-sectional area than the communication passage 252, and pressure loss due to the communication passage 253 is almost eliminated. In the present embodiment, the communication path 252 is provided, but the communication path 252 may not be provided.

The communication passage 252 constantly communicates the first chamber 16 and the chamber 151A with the internal chamber 261, and the communication passage 253 constantly communicates the internal chamber 261 with the oil reservoir chamber 85A and the reservoir chamber 13. These communication passages 252 and 253 supply the oil liquid in the one-side chamber 16 to the oil reservoir chamber 85A, thereby preventing sticking due to poor lubrication of the seal member 21. The communication passages 252 and 253 discharge air mixed in the one chamber 16.

In the shock absorber 11A, when the piston rod 15 moves to the expansion side extending the entire length of the expansion shock absorber 11A and the compression side extending the entire length of the compression shock absorber 11A, and the piston 18 moves to the side of the one-side chamber 16, and the pressure of the one-side chamber 16 increases, the pressure of the chamber 151A also increases via the communication passage 64, but a state may be delayed in which the pressure of the inner chamber 261 increases via the communication passage 252 having a high pressure loss. At this time, the upstream side of the elastic rubber portion 91A in the flow direction of the oil is the chamber 151A, and the downstream side is the inner chamber 261. The inner chamber 261 between the downstream side of the elastic rubber portion 91A and the reservoir chamber 13 has an internal pressure lower than the internal pressures of the one chamber 16 and the chamber 151A.

The elastic rubber portion 91A receives a radially outward force mainly at the pressure receiving portion 256 of the base end side tapered portion 239 due to the pressure difference between the one side chambers 16 and 151A and the inner chamber 261, the oil reservoir 85A, and the reservoir chamber 13. When the pressure difference between the first side chamber 16 and the chamber 151A and the inner chamber 261, the oil reservoir 85A, and the reservoir chamber 13 reaches a predetermined pressure, the elastic rubber portion 91A is deformed radially outward by the pressure received by the pressure receiving portion 256 of the distal end side tapered portion 239. Thereby, a radial gap is generated between the piston rod 15 and the upstream chamber 151A and the downstream oil reservoir chamber 85A are communicated with each other through the gap. That is, the elastic rubber portion 91A is formed so as to be able to communicate the upstream chamber 151A with the downstream inner chamber 261 when the pressure difference between the one chamber 16 and the reservoir chamber 13 reaches a predetermined pressure.

In the shock absorber 11A of the second embodiment described above, similarly, in the hydraulic damping region in which the hydraulic damping force is generated by the fixed orifice and the disc valves 41 and 42, which are not shown, the damping force is hardly generated by the fixed orifice and the disc valves 41 and 42, which are not shown, in the very low speed region in which the piston speed is lower. Therefore, the elastic force and the frictional resistance against the piston rod 15 by the seal member 21 and the friction generating member 22A and the frictional resistance against the cylinder 12 by the piston 18 become main generation sources of the damping force.

In the shock absorber 11A of the second embodiment, the pressures in the one side chamber 16 and the reservoir chamber 13 are substantially equal in the micro-amplitude region of the piston rod 15 and the piston 18 in which the hydraulic damping force is not generated. Therefore, the lip 255 of the elastic rubber portion 91A of the friction generating member 22A contacts the main shaft portion 38 of the piston rod 15 in a tightly bound state. Therefore, the sliding resistance to the piston rod 15 generated by the friction generating member 22A is high.

On the other hand, in the extension stroke and the compression stroke in the normal region (the hydraulic damping region described above) in which the amplitude is larger than the micro-amplitude region, when the piston speed becomes higher and the pressure of the one side chamber 16 becomes higher than the pressure of the reservoir chamber 13, the pressure of the chamber 151A communicating with the one side chamber 16 via the communication passage 64 also becomes higher. On the other hand, the pressure of the chamber 261 communicating with the chamber 151A via the communication passage 252 having a high pressure loss does not increase, and the inner chamber 261 has an internal pressure lower than the internal pressures of the one chamber 16 and the chamber 151A. At this time, the inner chamber 261 between the downstream side of the elastic rubber portion 91A and the reservoir chamber 13 becomes a low pressure chamber having an internal pressure lower than the internal pressure of the one chamber 16.

The elastic rubber portion 91A receives the pressure of the one-side chamber 16 and the chamber 151A, which is higher than the pressure of the inner chamber 261, the oil reservoir 85A, and the reservoir 13, generated in this manner at the pressure receiving portion 256 on the one-side chamber 16 side than the lip 255 in sliding contact with the piston rod 15, and deforms radially outward, so that the fastening force of the piston rod 15 to the main shaft portion 38 decreases, and the sliding resistance decreases.

When the piston speed is further increased and the pressure difference between the first chamber 16 and the chamber 151A and the inner chamber 261, the oil reservoir chamber 85A, and the reservoir chamber 13 reaches a predetermined pressure, the elastic rubber portion 91A is separated in the radial direction from the main shaft portion 38 of the piston rod 15, and the first chamber 16 and the chamber 151A on the upstream side in the flow direction of the oil liquid, and the oil reservoir chamber 85A and the reservoir chamber 13 on the downstream side are communicated with each other. At this time, the sliding resistance of the elastic rubber portion 91A against the piston rod 15 disappears.

As described above, in the damper 11A of the second embodiment, the friction generating member 22A generates a sliding force corresponding to the piston speed to the piston rod 15, as in the first embodiment. Therefore, the damper 11A of the second embodiment achieves the same effects as those of the first embodiment.

In addition, the damper 11A of the second embodiment is formed in such a shape that the base portion 92A forms the inner chamber 261 having an internal pressure lower than the internal pressure of the one side chamber 16. Therefore, the elastic rubber portion 91A can be covered with the base portion 92A, and the friction generating member 22A can be easily handled.

Further, since the base portion 92A is configured to have the communication passage 253 that communicates the inner chamber 261 and the oil reservoir 85A, the communication passage 253 can be easily formed.

Further, the base portion 92A is formed with a communication passage 252 that communicates the first chamber 16 and the inner chamber 261. Therefore, the communication path 252 can be easily formed, and the size of the communication path 252 can be easily changed to adjust the characteristics.

The first aspect of the above-described embodiment includes: a cylinder filled with a working fluid; an outer cylinder provided on an outer peripheral side of the cylinder; a storage chamber formed between the outer tub and the cylinder; a piston which is in sliding contact with an inner surface side of the cylinder and divides the inside of the cylinder into a first side chamber and a second side chamber; the piston is fixed at one end of the piston rod, and the other end of the piston rod extends out of the cylinder; a seal member that is in 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 of the cylinder defined by the seal member, for guiding the piston rod; a friction generating member provided at a position on one side of the cylinder divided by the seal member, and in sliding contact with the piston rod; the friction generating member includes an annular elastic rubber portion that is in sliding contact with the piston rod, and a base portion to which the elastic rubber portion is fixed, and the elastic rubber portion is formed so as to be able to communicate between an upstream side and a downstream side of the elastic rubber portion when a pressure difference between the one-side chamber of the cylinder and the reservoir chamber reaches a predetermined pressure. Thereby, good operation characteristics can be obtained.

A second aspect is the first aspect, wherein a low pressure chamber having an internal pressure lower than the internal pressure of the one-side chamber is formed between the downstream side of the elastic rubber portion and the reservoir chamber.

A third aspect is the second aspect wherein the low pressure chamber communicates with the reservoir chamber.

A fourth aspect is any one of the first to third aspects, wherein a lip portion that is in sliding contact with the piston rod is formed in the elastic rubber portion.

A fifth aspect is the fourth aspect, wherein the lip portion is formed on the sealing member side on an inner peripheral side of the elastic rubber portion, and a pressure receiving portion that receives a pressure of the one chamber is formed on the one chamber side.

Industrial applicability of the invention

By applying the above-described damper to this field, a damper that can obtain good operating characteristics can be provided.

Description of the reference numerals

11. 11A buffer

12 cylinder

13 storage chamber

14 outer cylinder

15 piston rod

16 side chamber

17 another side chamber

18 piston

20-bar guide

21 sealing member

22. 22A friction generating member

85 chamber (Low pressure chamber)

91. 91A elastic rubber part

92. 92A base part

155. 255 lip

156. 256 pressure receiving parts

261 inner chamber (Low pressure chamber)