JP2017003018A - Buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a buffer including an air spring, and capable of attaining smooth telescopic motion.SOLUTION: For a buffer, a first chamber member is loosely fitted to a chamber holder and a spring chamber formation member, and can move in a radial direction. Therefore, the first chamber member can move in the radial direction to an air piston. Consequently, even when lateral force causing bending moment to act on the buffer is input, the first chamber member is prevented from being excessively pressed against the air piston by radial play.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shock absorber.

  2. Description of the Related Art Conventionally, shock absorbers used in saddle riding vehicles have been developed in which air springs are used instead of metal coil springs in order to reduce the weight of the shock absorbers. The shock absorber using the air spring includes, for example, a cylinder, a rod that is movably inserted into the cylinder, and a tubular member that is attached to the end of the rod and forms a chamber between the cylinder. (For example, refer to Patent Document 1).

  In this shock absorber, a high-pressure gas is enclosed in the chamber to form an air spring, and the volume of the air chamber is expanded and contracted during expansion and contraction so that a spring reaction force corresponding to the expansion and contraction degree of the shock absorber can be obtained. It has become. Here, the air spring always urges the shock absorber in the extension direction by the internal pressure, exhibits a non-linear spring characteristic with respect to the stroke amount of the shock absorber, and when the suspension spring is constituted only by this air spring, The spring force is excessive with respect to the stroke amount, and the ride comfort in the vehicle is deteriorated. Therefore, in the conventional shock absorber, an airtight chamber is provided between the lower end of the tubular member and the compressor piston by sliding the lower end of the tubular member on the outer periphery of the cylinder.

  This hermetic chamber functions as an air spring with high-pressure gas enclosed therein and, unlike the above-described chamber, exhibits a spring force that biases the shock absorber in the compression direction.

  In this way, the shock absorber is provided with an air spring formed by an airtight chamber that exerts a spring force in the opposite direction to the air spring formed by the chamber in addition to the chamber, thereby realizing a spring characteristic similar to a coil spring. Thus, the ride comfort in the vehicle is improved.

JP-T-2001-501155

  In this shock absorber, since the tubular member employs a structure in which both the compressor piston and the cylinder are in sliding contact, the following problems arise.

  When a bending moment acts on the shock absorber, the tubular member is bent and strongly pressed against the compressor piston and cylinder, the frictional force generated between the tubular member and the compressor piston and cylinder increases, and the shock absorber smoothly expands and contracts. It will be disturbed.

  In addition, if the tubular member is not arranged concentrically with respect to both the cylinder and the compressor piston, the frictional force generated between the tubular member and the compressor piston and cylinder increases, so that the shock absorber can be smoothly expanded and contracted. Therefore, highly accurate dimensional management is required for each part.

  Therefore, an object of the present invention is to provide a shock absorber that can be smoothly expanded and contracted while having an air spring.

  In order to achieve the above object, in the shock absorber in the problem solving means of the present invention, the first chamber member is loosely fitted to the chamber holder and the spring chamber forming member, and is movable in the radial direction. Therefore, the first chamber member is movable in the radial direction also with respect to the air piston. Therefore, even if a lateral force that causes a bending moment to act on the shock absorber is input, the first chamber member does not need to be pressed too strongly against the air piston due to radial play. Therefore, when the first chamber member moves in the vertical direction with respect to the air piston due to the expansion and contraction of the shock absorber, the frictional force generated between the first chamber member and the air piston is caused by the lateral force input to the shock absorber. Is not excessive. Further, since the first chamber member is allowed to move in the radial direction with respect to the air piston and the first chamber member is aligned by the air piston, the friction force generated between the first chamber member and the air piston is excessive. Don't be. In addition, highly accurate dimensional management is not required for each component such as the first chamber member, the second chamber member, the cylinder, and the air piston.

  In the shock absorber of claim 2, the closing member is slidably contacted with the outer periphery of the cylinder to form a reaction force spring chamber with the air piston. Therefore, this shock absorber is provided with a reaction force spring chamber for exerting a damping force during expansion and contraction and for exerting an urging force in the opposite direction to the air spring by the air chamber. A spring characteristic proportional to the amount can be realized.

  Further, in the shock absorber according to the third aspect, the reaction force spring chamber exerts an urging force in a direction opposite to that of the air spring by the gas sealed inside. Therefore, in this shock absorber, a damping force is exhibited during expansion and contraction, and the air spring by the air chamber and the reaction force spring chamber functions as a suspension spring that exerts a resilient force in accordance with the stroke amount of the shock absorber. A spring characteristic proportional to the amount can be realized. Therefore, a suspension spring can be realized without using a coil spring, and the overall weight of the shock absorber can be reduced.

  Therefore, according to the shock absorber of the present invention, smooth expansion and contraction can be realized while the air spring is provided.

It is sectional drawing of the shock absorber in 1st embodiment of this invention.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, the shock absorber D in the first embodiment includes a cylinder Cy, a rod 2 that is movably inserted into the cylinder Cy, a chamber holder 13 that is attached to the rod 2, and one end that is a chamber. A cylindrical first chamber member 22 is fitted to the holder 13 with play in the radial direction, and one end is fixedly attached to the chamber holder 13 and arranged on the outer periphery of the first chamber member 22, and the inside is first. A cylindrical second chamber member 23 communicated with one chamber member 22, an air piston 14 attached to the cylinder Cy and slidably in contact with the inner periphery of the first chamber member 22, the first chamber member 22 and the second chamber member A spring chamber forming member 24 as a closing member for closing a gap between the chamber members 23 is provided.

  Hereinafter, each part will be described. The cylinder Cy includes a cylindrical inner tube 1 having a cap 5 that closes the lower end in FIG. 1 and an outer tube 6 attached to the outer periphery of the inner tube 1. An annular rod guide 3 is attached. Further, a step portion 1a is provided on the outer periphery of the inner tube 1, and the outer diameter in FIG. 1 that is closer to the rod 2 than the step portion 1a is smaller than the lower outer diameter of the step portion 1a. Thus, a small diameter portion 1b is formed. An outer tube 6 is attached to the small-diameter portion 1b of the inner tube 1, and the lower end of the outer tube 6 is in contact with the step portion 1a, so that the lower tube 1 is restricted from moving downward. ing.

  The outer tube 6 has a smooth outer surface by plating or polishing the outer periphery. Further, the inner tube 1 is partitioned into an extension side chamber R1 and a pressure side chamber R2 both filled with liquid by a piston 7 connected to the lower end of the rod 2 in FIG. As the liquid filled in the inner tube 1, for example, hydraulic oil is used, but other liquids such as water, an aqueous solution, an electrorheological fluid, and a magnetorheological fluid can be used.

  The piston 7 is provided with an extension side flow path 7a and a pressure side flow path 7b communicating the extension side chamber R1 and the pressure side chamber R2. In addition, an extension side leaf valve 8 that opens and closes the outlet end of the extension side channel 7a is stacked at the lower end of the piston 7 in FIG. 1, and the outlet end of the pressure side channel 7b is connected to the upper end of the piston 7 in FIG. A pressure-side leaf valve 9 that opens and closes is stacked. The extension-side leaf valve 8 and the compression-side leaf valve 9 are annular and are fixed to the tip of the rod 2 together with the piston 7 by a piston nut 10, and are allowed to bend on the outer peripheral side. Therefore, the expansion-side leaf valve 8 can open the expansion-side flow path 7a when bent under the pressure of the expansion-side chamber R1, and the compression-side leaf valve 9 opens the pressure-side flow path 7b when bent under the pressure of the compression side chamber R2. it can.

  The cap 5 that closes the lower end of the inner tube 1 includes a mounting portion 5e for connecting the shock absorber D to the vehicle, and a cylindrical tank T along the side of the inner tube 1. A free piston 11 is slidably inserted in the interior. The free piston 11 divides the tank T into a gas chamber G filled with gas and a liquid chamber L filled with liquid, and the liquid chamber L flows into the pressure side chamber R2 provided in the cap 5. The passage 5a communicates with the suction passage 5b. The discharge flow path 5a is provided with a damping valve 5c that allows only the flow of liquid from the pressure side chamber R2 to the liquid chamber L and gives resistance to this flow, and the other suction flow path 5b includes the liquid chamber L from the liquid chamber L. A check valve 5d that allows only the flow of liquid toward the pressure side chamber R2 is provided. The tank T may be eliminated, and the discharge flow path 5a, the suction flow path 5b, the damping valve 5c, the check valve 5d, and the reservoir may be provided in the cylinder Cy.

  1, the rod 2 extends outside the cylinder Cy through an annular rod guide 3 attached to the cylinder Cy at the upper end in FIG. The rod guide 3 is annular and includes a flange-shaped air piston 14 having an outer diameter larger than the outer diameter of the cylinder Cy on the outer periphery of the upper end in FIG. The small diameter portion 15 has a small outer diameter. Further, a screw portion 16 is provided on a part of the outer periphery of the small diameter portion 15 of the rod guide 3. The air piston 14 includes an annular groove 14a formed on the outer periphery and a piston seal 20 mounted in the annular groove 14a. As described above, the rod guide 3 including the air piston 14 may be attached to the cylinder Cy, and the air piston 14 may be indirectly attached to the cylinder Cy, or the air piston 14 may be directly and integrally provided on the outer periphery of the cylinder Cy. May be attached.

  Then, when the small diameter portion 15 is inserted into the outer tube 6 and the inner tube 1 constituting the cylinder Cy and the screw portion 16 is screwed to the inner periphery of the inner tube 1, the rod guide 3 is fixed to the inner tube 1. Further, by screwing the rod guide 3 to the inner tube 1, the outer tube 6 is sandwiched between the step portion 1 a and the lower end of the air piston 14 and fixed to the inner tube 1 and integrated. When the rod guide 3 is attached to the cylinder Cy in this manner, the rod guide 3 faces the air chamber C provided on the outer periphery of the rod 2.

  Further, on the outer periphery of the small diameter portion 15 of the rod guide 3, an annular seal 18 that contacts the inner periphery of the outer tube 6 and an annular seal 17 that contacts the inner periphery of the inner tube 1 are mounted with the screw portion 16 interposed therebetween. . Further, on the inner periphery of the rod guide 3, a cylindrical bush 19 that slides on the outer periphery of the rod 2 and guides the movement in the vertical direction in FIG. An air seal AS that is disposed on the upper air chamber C side and that is in sliding contact with the outer periphery of the rod 2 to prevent gas from entering the cylinder Cy, and a cylinder Cy that is formed of rubber, resin, or the like and that is lower than the bush 19 in FIG. And a liquid seal LS which is disposed on the side and slidably contacts the outer periphery of the rod 2 to prevent liquid leakage from the cylinder Cy.

  Thus, since the liquid seal LS is provided in the rod guide 3, the inside of the cylinder Cy is sealed and the inside of the cylinder Cy is kept liquid-tight. Further, since the rod guide 3 is provided with the air seal AS, the air chamber C is kept airtight, and gas intrusion into the cylinder Cy is prevented.

  The rod guide 3 is provided with a through hole 21 that opens from between the bush 19 and the liquid seal LS and communicates with the screw portion 16 of the small diameter portion 15. That is, the through hole 21 is between the rod guide 3 and the rod 2 and has one end communicating with the space S between the air seal AS and the liquid seal LS. The space S is an annular gap between the rod guide 3 and the rod 2 and is a space partitioned between the air seal AS and the liquid seal LS. Further, the other end of the through hole 21 communicates with a gap between the outer tube 6 and the inner tube 1 through the rod guide 3 and the inner tube 1. In order to ensure communication between the gap between the outer tube 6 and the inner tube 1 and the through hole 21, the annular seal 18 is disposed above the upper end of the inner tube 1, and the other end of the through hole 21 is annular. Care is taken to open between the seal 17 and the annular seal 18.

  The space S is communicated to the outside of the cylinder Cy through the through hole 21, the gap between the rod guide 3 and the inner tube 1 and the gap between the outer tube 6 and the inner tube 1, and is open to the atmosphere. . Therefore, in the present embodiment, the space S is formed by the pressure relief passage 4 constituted by the through hole 21, the gap between the rod guide 3 and the inner tube 1 and the gap between the outer tube 6 and the inner tube 1. It communicates outside the cylinder Cy.

  Returning, the attachment member 12 and the annular chamber holder 13 for connecting the shock absorber D to the vehicle are attached to the upper end of the rod 2 in FIG. The chamber holder 13 is annular, and includes a mounting portion 13a attached to the outer periphery of the upper end of the rod 2 in FIG. 1 and a cylindrical portion 13b extending downward from the outer periphery of the mounting portion 13a in FIG. . An annular groove 13 c is provided below the attachment portion 13 a of the chamber holder 13. An upper end of a bellows-like bump cushion rubber BR disposed on the outer periphery of the rod 2 is compression-fitted in the annular groove 13 c, and the bump cushion rubber BR is held by the chamber holder 13.

  Further, the chamber holder 13 has a cylindrical upper end of the first chamber member 22 in FIG. 1 into which the air piston 14 provided on the rod guide 3 is slidably inserted. The upper end in FIG. 1 of the 2nd chamber member 23 which is fitted and is cylindrical and arrange | positioned at the outer peripheral side of the 1st chamber member 22 is attached.

  The first chamber member 22 has a cylindrical shape, and the upper end in FIG. 1 is fitted into the inner periphery of the cylindrical portion 13b of the chamber holder 13 so as to be slightly movable in the radial direction. It is fitted (freely fitted) with play in the direction. Further, a piston seal 20 mounted on the air piston 14 is in sliding contact with the inner periphery of the first chamber member 22, and the opening end of the first chamber member 22 is airtightly closed.

  The second chamber member 23 has a cylindrical shape, and the upper end in FIG. 1 is screwed and attached to the outer periphery of the cylindrical portion 13 b of the chamber holder 13. A notch 13d is provided from the inner periphery of the cylindrical portion 13b of the chamber holder 13 to the mounting portion 13a, and an annular gap between the first chamber member 22 and the second chamber member 23 is provided through the notch 13d. Is communicated.

  As a closing member that forms a reaction force spring chamber BS between the first piston 22 and the second chamber member 23 at the cylinder side, which is the lower end in FIG. The spring chamber forming member 24 is attached.

  Specifically, the spring chamber forming member 24 is fitted to the lower end of the first chamber member 22 and is screwed to the inner periphery of the second chamber member 23, and a view of the cylindrical body 24a. 1 An annular inner flange portion 24 b that protrudes from the middle lower end to the inner peripheral side and slidably contacts the outer periphery of the outer tube 6, and an annular seal member 25 that is attached to the inner periphery of the inner flange portion 24 b and slidably contacts the outer periphery of the outer tube 6. 26, an air injection hole 24c that opens from the lower end and penetrates the cylindrical main body 24a, an air injection hole 24d that opens from the lower end and penetrates the inner periphery of the cylindrical main body 24a, and an air injection hole 24c An air valve 27 and an air valve 28 provided in the air injection hole 24d are provided.

  The first chamber member 22 is fitted to the spring chamber forming member 24 with a fitting gap, that is, fitted (freely fitted) with play in the radial direction. However, a slight movement in the radial direction is possible. The spring chamber forming member 24 includes an annular seal 24e that is in close contact with the outer periphery of the first chamber member 22 and an annular seal 24f that is in close contact with the inner periphery of the second chamber member 23. An annular gap between the member 22 and the second chamber member 23 is sealed. Therefore, the air chamber C is formed by the air piston 14, the chamber holder 13, the first chamber member 22, the second chamber member 23, and the spring chamber forming member 24, and the above-described annular gap is formed in the first chamber member 22. It becomes room C. Further, since the annular gap between the first chamber member 22 and the second chamber member 23 is also a part of the air chamber C, even if the shock absorber D is contracted to the maximum and the air chamber C is contracted to the maximum, the air The minimum volume of the chamber C can be secured and the pressure in the air chamber C does not become excessive. The chamber holder 13 can be integrated and integrated with one or both of the first chamber member 22 and the second chamber member 23.

  The spring chamber forming member 24 is in sliding contact with the outer tube 6 with seal members 25 and 26 provided on the inner periphery of the inner flange portion 24 b, and is counteracted by the spring chamber forming member 24, the outer tube 6 and the air piston 14. A force spring chamber BS is formed. Since the outer periphery of the outer tube 6 is a smooth surface, the seal members 25 and 26 can close the reaction force spring chamber BS and can reduce sliding resistance.

  The air chamber C can be filled with gas from an air valve 27 provided in the spring chamber forming member 24, and a predetermined amount of gas is enclosed. In addition to the use of air, an inert gas or the like can be used as the gas. The reaction force spring chamber BS can be filled with a gas from an air valve 28 provided in the spring chamber forming member 24, and a predetermined amount of gas is enclosed. In the air chamber C in which the gas is sealed, the air piston 14 is pushed down by the internal gas pressure in FIG. 1, so that the spring force for urging the rod 2 away from the cylinder Cy, that is, the shock absorber D in the extending direction. It functions as an air spring that exerts an energizing spring force. On the other hand, the reaction force spring chamber BS in which the gas is enclosed pushes up the air piston 14 in FIG. 1 with the internal gas pressure, so that the spring force that urges the rod 2 in the direction of entering the cylinder Cy, that is, the buffer It functions as an air spring that exerts a spring force that biases the container D in the compression direction.

  The air spring formed by the air chamber C always urges the shock absorber D in the extending direction by the internal pressure, and exerts a large elasticity even when the shock absorber D strokes in a slightly contracting direction. The spring characteristic which generate | occur | produces a nonlinear elastic force with respect to the stroke amount of the buffer D is shown. On the other hand, the reaction force spring chamber BS functions as an air spring that urges the shock absorber D in the opposite direction to the air spring formed by the air chamber C. Accordingly, the total spring characteristic of the air spring formed by the air chamber C and the air spring formed by the reaction force spring chamber BS is approximated to a spring characteristic like a coil spring proportional to the stroke amount of the shock absorber D. It can be made with the characteristics to be.

  The shock absorber D is configured as described above, and the operation thereof will be described below. First, when the shock absorber D extends, the rod 2 moves upward in FIG. 1 with respect to the cylinder Cy, the piston 7 is displaced upward in the cylinder Cy, the expansion side chamber R1 is compressed, and the compression side chamber R2 is expanded. Is done.

  Then, the pressure in the expansion side chamber R1 to be compressed rises, and the liquid in the expansion side chamber R1 pushes and opens the expansion side leaf valve 8 and passes through the expansion side flow path 7a provided in the piston 7, thereby compressing the pressure side chamber R2. Move to. The rod 2 retracts from the cylinder Cy, and the volume of liquid in which the rod 2 retracts from the cylinder Cy is insufficient in the cylinder Cy. However, the check valve 5d is opened, and the liquid corresponding to the shortage flows through the suction flow path 5b. And supplied from the liquid chamber L to the pressure side chamber R2. Since the pressure side chamber R2 receives the supply of liquid from the liquid chamber L with respect to the expansion side chamber R1 where the pressure increases, the pressure in the tank T becomes almost equal to the pressure in the expansion side chamber R1 and the pressure side chamber R2. The pressure acts on the piston 7, and the shock absorber D exerts a damping force that prevents the extension operation. Further, as the rod 2 is raised in FIG. 1, the first chamber member 22 is separated from the air piston 14 to increase the volume in the air chamber C, and the spring chamber forming member 24 is moved upward with respect to the cylinder Cy. It moves and the volume of the reaction force spring chamber BS decreases. In this way, the volume of the air chamber C is expanded and the reaction force spring chamber BS is compressed by the extension operation of the shock absorber D, so that the elastic force of the air spring formed by the air chamber C is reduced, and the reaction force spring is reduced. The resilience of the air spring formed by the chamber BS increases. As a result, the total elastic force of the air spring formed by the air chamber C and the air spring formed by the reaction force spring chamber BS decreases and decreases.

  Next, when the shock absorber D is compressed, the rod 2 moves downward in FIG. 1 with respect to the cylinder Cy, the piston 7 is displaced downward in the cylinder Cy, the compression side chamber R2 is compressed, and the expansion side chamber R1. Is enlarged.

  Then, the pressure in the pressure side chamber R2 to be compressed rises, and the liquid in the pressure side chamber R2 moves to the expansion side chamber R1 through the pressure side flow path 7b provided in the piston 7 by pushing the pressure side leaf valve 9 open. . Further, the rod 2 enters the cylinder Cy and the volume of liquid in which the rod 2 enters the cylinder Cy becomes excessive in the cylinder Cy, but the excess liquid is discharged by pushing the damping valve 5c open. The fluid is discharged from the pressure side chamber R2 to the liquid chamber L through the passage 5a. In this way, resistance is provided by the pressure-side leaf valve 9 and the damping valve 5c to the flow of liquid from the pressure-side chamber R2 toward the expansion-side chamber R1 and the liquid chamber L, so that the pressure in the pressure-side chamber R2 increases. The pressure in the expansion side chamber R1 to be expanded decreases. Accordingly, a difference occurs between the pressures of the compression side chamber R2 and the expansion side chamber R1, and this differential pressure acts on the piston 7 so that the shock absorber D exhibits a damping force that prevents the contraction operation. Further, as the rod 2 descends in FIG. 1, the first chamber member 22 approaches the air piston 14 and the volume in the air chamber C decreases, and the spring chamber forming member 24 moves downward relative to the cylinder Cy. Thus, the volume of the reaction force spring chamber BS is expanded. In this way, the air chamber C is compressed by the contraction operation of the shock absorber D and the volume of the reaction force spring chamber BS is expanded, so that the elastic force of the air spring formed by the air chamber C increases, and the reaction force spring The resilience of the air spring formed by the chamber BS is reduced. Thereby, the total elastic force of the air spring formed by the air chamber C and the reaction spring chamber BS is increased and increased.

  Thus, the shock absorber D exhibits a damping force during expansion and contraction, and the air spring by the air chamber C and the reaction force spring chamber BS exhibits a resilient force that supports the vehicle body in accordance with the stroke amount of the shock absorber D. It functions as a suspension spring that achieves spring characteristics that are almost proportional to the stroke amount. Therefore, a suspension spring can be realized without using a coil spring, and the overall weight of the shock absorber D can be reduced.

  Instead of enclosing gas in the reaction force spring chamber BS and forming an air spring in the reaction force spring chamber BS, a coil spring is provided between the air piston 14 and the inner flange portion 24b of the spring chamber forming member 24. Thus, a spring characteristic proportional to the stroke amount of the shock absorber D may be obtained. In that case, since there is no need to enclose the gas in the reaction force spring chamber BS, there is no need to seal the reaction force spring chamber BS, so the seal members 25 and 26 can be omitted or the tightening force can be reduced. The sliding friction during the relative movement between the chamber member 23 and the cylinder Cy can be reduced. In this way, since the sliding portion between the cylinder Cy and the seal members 25 and 26 is reduced, the shock absorber D can be expanded and contracted more smoothly. Further, since the seal members 25 and 26 are unnecessary, it is not necessary to make the outer peripheral surface of the cylinder Cy smooth. Further, when the pressure side passage 4 is connected to the reaction force spring chamber BS, the outer tube 6 can be eliminated.

  In the shock absorber D of the present invention, the first chamber member 22 is loosely fitted to the chamber holder 13 and the spring chamber forming member 24 and is movable in the radial direction. Therefore, the first chamber member 22 can also move in the radial direction with respect to the air piston 14. Therefore, even if a lateral force that applies a bending moment to the shock absorber D is input, the first chamber member 22 is not excessively pressed against the piston seal 20 mounted on the outer periphery of the air piston 14 due to radial play. That's it. Therefore, when the first chamber member 22 moves in the vertical direction in FIG. 1 with respect to the air piston 14 due to expansion and contraction of the shock absorber D, the frictional force generated between the first chamber member 22 and the piston seal 20 is buffered. The lateral force input to the container D does not become excessive. Further, since the first chamber member 22 is allowed to move in the radial direction with respect to the air piston 14 and the first chamber member 22 is aligned by the air piston 14, the first chamber member 22 is generated between the first chamber member 22 and the piston seal 20. The friction force is not excessive. Therefore, in order to smoothly expand and contract the shock absorber D, high-precision dimensional control is not required for each component such as the first chamber member 22, the second chamber member 23, the cylinder Cy, and the air piston 14. As described above, according to the shock absorber D, the frictional force generated between the first chamber member 22 and the air piston 14 does not become excessive. Therefore, the shock absorber D can be expanded and contracted smoothly, the damping force that cannot be controlled by the frictional force is not exhibited, the riding comfort in the vehicle can be improved, and high-accuracy dimensional control is required for each component forming the air chamber C. You do n’t have to.

  Further, the shock absorber D of the present embodiment includes a cylindrical second chamber member 23 that is disposed on the outer periphery of the first chamber member 22 and communicates with the inside of the first chamber member 22, thereby forming a spring chamber. The annular gap between the chamber member 22 and the second chamber member 23 is closed by the member 24, and the annular gap is also used as the air chamber C. Since the volume of the annular gap does not change even when the shock absorber D expands and contracts, the volume of the air chamber C can be secured larger when the shock absorber D is fully contracted, and the pressure in the air chamber C when the shock absorber D is contracted is maximum. Can be prevented from becoming excessive.

  Further, in the shock absorber D of the present embodiment, the space S between the air seal AS and the liquid seal LS on the inner periphery of the rod guide 3 facing the air chamber C is communicated to the outside of the cylinder Cy by the decompression passage 4. Yes. As a result, even if the liquid in the cylinder Cy enters the space S through the expansion and contraction of the shock absorber D and the liquid in the cylinder Cy enters, the pressure in the space S is not accumulated by the depressurization passage 4. Therefore, the inside of the space S does not become high pressure, and high pressure does not act from the space S side which is the back surface of the air seal AS. Therefore, the sealing performance of the air seal AS is not hindered, and the gas in the air chamber C enters the cylinder Cy. Can be prevented. Furthermore, since a high pressure does not act on the liquid seal LS from the space S side, the liquid seal LS can also exhibit a satisfactory sealing performance, and the effect of suppressing liquid leakage into the space S is improved.

  Therefore, according to the shock absorber D of the present embodiment, since the sealing performance of the air seal AS is not impaired, the gas in the air chamber C can be prevented from entering the cylinder Cy while the air spring is provided. There is no need to adversely affect the attenuation characteristics.

  In addition, since the depressurization passage 4 opens the space S to the atmosphere, the liquid that has entered the space S can be discharged out of the shock absorber D, and the pressure increase in the space S can be reliably prevented. The extraction passage 4 may communicate with the sealed chamber in which the space S is provided outside the cylinder Cy. The volume of the sealed chamber may be set to such an extent that the amount of liquid expected to leak from the cylinder Cy into the sealed chamber does not cause a pressure that adversely affects the air seal AS. Can prevent dust and water from entering.

  Further, in the shock absorber D of the present embodiment, the cylinder Cy is provided with the outer tube 6 on the outer periphery of the inner tube 1 and the inner tube 1, the air chamber forming member 24 that closes the end of the air chamber C being in sliding contact, Since a part of the passage 4 is formed by a gap between the inner tube 1 and the outer tube 6, it is possible to prevent dust, rainwater, and the like from entering the space S from the outside of the shock absorber D. In addition, since the gap between the outer tube 6 and the inner tube 1 is used as a part of the decompression passage 4, even if the reaction force spring chamber BS is arranged on the outer periphery of the cylinder Cy, While avoiding the air chamber C, the space S can be opened to the atmosphere with a simple structure. If the pressure relief passage 4 is not provided, it is not necessary to open the space S to the atmosphere using the gap between the outer tube 6 and the inner tube 1, so that the outer periphery of the inner tube 1 is made a smooth surface. The outer tube 6 may be abolished.

  This is the end of the description of the embodiments of the present invention, but the scope of the present invention is not limited to the details shown or described.

DESCRIPTION OF SYMBOLS 2 ... Rod, 13 ... Chamber holder, 13a ... Mounting part, 14 ... Air piston, 22 ... First chamber member, 23 ... Second chamber member, 24 ... Spring Chamber forming member (closing member), BS ... reaction force spring chamber, C ... air chamber, Cy ... cylinder, D ... shock absorber, R1 ... extension side chamber, R2 ... pressure side chamber , S ... space

Claims (3)

A cylinder,
A rod movably inserted into the cylinder;
A chamber holder attached to the rod;
A cylindrical first chamber member having one end fitted to the chamber holder with play in the radial direction;
A cylindrical second chamber member having one end fixedly attached to the chamber holder and disposed on the outer periphery of the first chamber member, and the inside communicating with the first chamber member;
An air piston attached to the cylinder and in sliding contact with the inner periphery of the first chamber member;
The other end of the first chamber member is fixedly attached to the other end of the second chamber member, and the other end of the first chamber member is fitted with play in the radial direction, and between the first chamber member and the second chamber member. A closing member for closing the annular gap of
An air chamber functioning as an air spring is formed by the chamber holder, the first chamber member, the second chamber member, the air piston, and the closing member. The shock absorber according to claim 1, wherein the closing member is in sliding contact with the outer periphery of the cylinder to form a reaction force spring chamber between the closing member and the air piston. The shock absorber according to claim 2, wherein the reaction force spring chamber exerts an urging force in a direction opposite to the air spring by a gas sealed inside.

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