JP5403755B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber.

  Conventionally, a shock absorber set to a double rod type is used by being interposed between a vehicle body and an axle of a vehicle, for example, a cylinder, a rod inserted into the cylinder, and a middle of the rod. The piston includes a piston that separates two pressure chambers in the cylinder, and a reservoir that is formed in a cylindrical extending portion that extends into the cylinder and into which one end of the rod is inserted.

  According to this double rod type shock absorber, the pressure chamber and the reservoir are communicated with each other through the gap between the rod and the bearing member that guides the rod, and the volume change due to the change in the hydraulic oil temperature is compensated by the reservoir. (For example, refer to Patent Document 1).

  In such a shock absorber, as described above, the rod is inserted into the reservoir, and the pressure in the air chamber always acts on the rod, and this extends the shock absorber as a rod reaction force. In addition, since the rod changes the volume of the air chamber in the reservoir during expansion and contraction of the shock absorber, the rod reaction force changes.

  Therefore, when such a shock absorber is applied to a vehicle, the rod reaction force not only affects the vehicle height, but also affects the ride comfort in the vehicle, so the pressure in the air chamber is necessarily limited. It cannot be set freely.

  Therefore, as a double rod type shock absorber having a structure in which the pressure in the air chamber does not act on the rod, a pipe disposed around the outer periphery of one end of the rod and a cylinder covering the pipe are provided, and a reservoir is provided between the pipe and the cylinder. There is a proposal of a shock absorber in which the pressure in the reservoir does not act on the rod (see Patent Document 2).

JP 2004-270902 A JP 2009-127760 A

  In the newly proposed shock absorber, the pressure in the air chamber does not act on the rod even if the pressure in the reservoir is set high to increase the apparent rigidity of the hydraulic oil in the shock absorber. The degree of freedom in setting the damping force generated by the shock absorber and the responsiveness can be dramatically increased without impairing the ride comfort in the vehicle.

  However, in the proposed shock absorber, the reservoir is arranged below the cylinder. For example, when the shock absorber is assembled or when the leaf valve assembled to the rod together with the piston is replaced, The problem is that it takes a lot of labor to remove the air that has entered the passage between the reservoir provided in the valve housing that incorporates the variable pressure damping valve and the pressure chamber, and the passage that connects the pressure chamber, and the work time also increases. There is.

  Therefore, the present invention was devised to improve the above-described problems, and the object of the present invention is to reduce the air bleeding work in the assembly process and maintenance, and to shorten the work time. Is to provide a shock absorber.

  In order to achieve the above object, the means for solving the problems of the present invention includes a cylinder, a rod movably inserted into the cylinder, an intermediate portion of the rod, and slidably inserted into the cylinder. In a shock absorber provided with a piston that separates two pressure chambers and configured as a double rod type, an outer cylinder that covers the cylinder and forms an air vent passage between the cylinder and one end of a rod protruding from the cylinder An inner cylinder that is arranged on the outer periphery and forms an annular gap with the outer cylinder, and an annular cylinder that slidably contacts the outer circumference of the inner cylinder and the inner circumference of the outer cylinder and that divides the annular gap into an air chamber and a liquid chamber A free passage, a communication passage that communicates the liquid chamber and the pressure chamber adjacent to the liquid chamber, and an orifice provided in the middle of the communication passage, and the fluid chamber and the air vent passage communicate with each other. .

  According to the shock absorber of the present invention, the gas mixed in the liquid chamber or the communication passage can be quickly discharged out of the shock absorber through the air vent passage during the liquid injection. Accordingly, it is possible to reduce the air bleeding work in the assembly process and maintenance of the shock absorber, and to shorten the work time.

  In addition, even if bubbles are generated in the liquid in the liquid chamber after the assembly of the shock absorber is completed, the gas is only guided to the air vent passage and the gas is accumulated above the air vent passage. Mixing of gas into the room can be prevented.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a shock absorber according to an embodiment. As shown in FIG. 1, a shock absorber D according to an embodiment is provided in a cylinder 1, a rod 2 that is movably inserted into the cylinder 1, and an intermediate portion of the rod 2 and slides in the cylinder 1. A piston 3 that is freely inserted and separates the two pressure chambers R1 and R2, an outer cylinder 4 that covers the cylinder 1 and forms an air vent passage 6 between the cylinder 1, and a rod 2 that protrudes from the cylinder 1 An inner cylinder 5 disposed on the outer periphery of one end 2a of the inner cylinder 5 and forming a reservoir R with the outer cylinder 4. The inner cylinder 5 is in sliding contact with the outer periphery of the inner cylinder 5 and the inner periphery of the outer cylinder 4, and the interior of the reservoir R An annular free piston 7 that is divided into a liquid chamber L, a communication passage 8 that connects the liquid chamber L and the pressure chamber R2 adjacent to the liquid chamber L, and an orifice 9 provided in the middle of the communication passage 8 The liquid chamber L and the air vent passage 6 communicate with each other. It has been.

  Hereinafter, each member will be described in detail. The cylinder 1 is closed at its upper and lower ends by rod guides 10 and 11 each having an annular shape, and the cylinder 1 is separated by a piston 3 slidably inserted into the cylinder 1. Two pressure chambers R1 and R2 are partitioned, and these pressure chambers are filled with a liquid such as hydraulic oil.

  The piston 3 has an annular shape and is attached to the middle of a rod 2 that is movably inserted into the cylinder 1, and has ports 3a and 3b that communicate the pressure chamber R1 and the pressure chamber R2.

  A leaf valve Va that opens and closes the port 3a is stacked and attached to an intermediate portion of the rod 2 above the piston 3 in FIG. 1, and a leaf valve Vb that opens and closes the port 3b is located below the piston 3 in FIG. Are stacked and attached to an intermediate portion of the rod 2.

  Furthermore, one end 2a of the rod 2 which is the lower end in FIG. 1 is inserted into a cylindrical bearing 13 which is fixed inside the annular rod guide 11 which closes the lower end in FIG. The other end 2b of the rod 2 that is the upper end in FIG. 1 is inserted into a cylindrical bearing 12 that is fixed to the inside of an annular rod guide 10 that closes the upper end in FIG. It protrudes outside.

  Note that the one end 2a of the rod 2 is not connected to the vehicle body or axle to be controlled, and no axial force is applied, so that it may be hollow for the purpose of weight reduction.

  An outer cylinder 4 is provided outside the cylinder 1 so as to cover the cylinder 1 and form an annular air vent passage 6 with the cylinder 1. The outer cylinder 4 is made of aluminum. It is longer than the cylinder 1 and extended downward from the lower end of the cylinder 1 so that the outer periphery of the one end 2a can be covered even if one end 2a of the rod 2 protrudes from the lower end of the cylinder 1 to the maximum. It has become. That is, the stroke range of the one end 2a of the rod 2 can be covered. Further, a rod guide 10 disposed on the upper side is fitted and fixed to the inner periphery of the upper end in FIG. 1 of the outer cylinder 4, and a small diameter portion 4 a is provided with the inner periphery of the intermediate portion having a small diameter. The small-diameter portion 4a has a rod guide fitting portion 4b in which the rod guide 11 is fitted on the lower side in FIG. 1 and an inner cylinder holding member that holds an inner cylinder 5 described later having an inner diameter smaller than that of the rod guide fitting portion 4b. In addition to the portion 4c, a plurality of through holes 4d penetrating the small diameter portion 4a along the axial direction are provided. The through hole 4d faces the lower end of the air vent passage 6 described above, and the open end of the through hole 4d can be viewed directly through the air vent passage 6 when the shock absorber D is viewed from the vertical direction that is the axial direction. It can be done. The number of the through holes 4d may be set as many as possible, but it is preferable to provide a large number if there is no problem in strength.

  Further, a seal ring 14 is interposed between the outer cylinder 4 and the rod guide 10 to seal between the outer cylinder 4 and the rod guide 10. Further, a seal member 15 is stacked above the rod guide 10, and the seal member 15 is fastened and fixed to the rod guide 10 by a cover 16 screwed to the outer cylinder 4.

  The rod guide 10 includes a fitting portion 10 a that fits the cylinder 1 at the lower end, and a step portion 10 b is formed on the outer periphery, and positions the cylinder 1 in the radial direction with respect to the outer cylinder 4. Further, the rod guide 10 is provided with a through hole 10c penetrating in the axial direction.

  In addition, a lip portion 15 a that is in sliding contact with the outer periphery of the other end 2 b of the rod 2 is provided on the inner periphery of the seal member 15, and this lip portion 15 a is provided through a through hole 10 c provided in the rod guide 10. The pressure in the pressure chamber R1 acts, and the pressure is pressed against the outer periphery of the other end 2b of the rod 2 to tightly seal the outer periphery of the other end 2b of the rod 2 tightly. Further, an outer peripheral seal portion 15 b that is in close contact with the rod guide 10 is provided on the outer periphery of the seal member 15, so that the space between the rod guide 10 and the seal member 15 is tightly sealed.

  Therefore, the seal member 15 seals between the other end 2 b of the rod 2 and the rod guide 10, and seals between the outer cylinder 4 and the rod 2 in cooperation with the seal ring 14.

  Returning, the rod guide 11 is fitted in the rod guide fitting portion 4b provided on the upper side of the small diameter portion 4a of the outer cylinder 4, and between the upper end of the inner cylinder holding portion 4c and the rod guide 11 is inserted. A seal member 17 that seals between the rod guide 11 and the one end 2a of the rod 2 is interposed. A seal ring 24 is interposed between the rod guide 11 and the cylinder 1 to seal between the rod guide 11 and the cylinder 1.

  The rod guide 11 is provided in the middle in FIG. 1 and has a large-diameter portion 11a that is in contact with the lower end in FIG. 1 and serves as one end of the cylinder 1. The rod guide 11 is on the upper side in FIG. 1 is fitted to the lower end in FIG. 1 which is one end of the small-diameter cylinder 1 and the rod guide fitting portion 4b which is lower in FIG. 1 than the large-diameter portion 11a and smaller in diameter than the large-diameter portion 11a. The outer cylinder fitting portion 11c to be joined, the through hole 11d leading from the upper end of the fitting portion 11b to the lower end of the outer cylinder fitting portion 11c along the axial direction, and the fitting portion 11b serving as the end portion on the pressure chamber R2 side. A through hole 11e that opens from the upper end and communicates with the outer periphery of the large diameter portion 11a is provided.

  A plug 25 having an orifice 9 is screwed to the outlet end on the fitting portion 11b side of the through hole 11e so that the orifice 9 provides resistance to the flow of liquid passing through the through hole 11e. It has become. The large-diameter portion 11a is provided with a relief portion 11f having a shape obtained by cutting the outer periphery of the lower end facing the upper end of the small-diameter portion 4a into an arc shape so as not to block the through hole 4d provided in the small-diameter portion 4a. . The relief portion 11f may be formed such that the outer periphery of the lower end of the small diameter portion 4a has a tapered surface shape.

  In addition, a lip portion 17 a that is slidably in contact with the outer periphery of one end 2 a of the rod 2 is provided on the inner periphery of the seal member 17, and pressure is applied to the lip portion 17 a through a through hole 11 d provided in the rod guide 11. The pressure in the chamber R2 is acting, and the pressure is pressed against the outer periphery of the one end 2a of the rod 2 to tightly seal the outer periphery of the one end 2a of the rod 2 tightly. Further, an outer peripheral seal portion 17 b that is in close contact with the rod guide 11 is provided on the outer periphery of the seal member 17, so that the space between the rod guide 11 and the seal member 17 is tightly sealed.

  Thus, in order from the bottom, the seal member 17, the rod guide 11, the cylinder 1, the rod guide 10, and the seal member 15 are inserted into the outer cylinder 4, and the cover 16 is placed on the inner periphery of the upper end of the outer cylinder 4 in FIG. When screwed, the respective members are sandwiched between the small diameter portion 4 a of the outer cylinder 4 and the cover 16, and the respective members are fixed in the outer cylinder 4. In addition, since these members are aligned in the radial direction by the outer cylinder 4, smooth expansion and contraction of the assembled shock absorber D is ensured.

  Further, the upper end of the inner cylinder 5 is screwed and held in the inner cylinder holding portion 4 c in the small diameter portion 4 a of the outer cylinder 4, and one end 2 a of the rod 2 is inserted into the inner periphery of the inner cylinder 5. An annular reservoir R is formed between the inner cylinder 5 and the outer cylinder 4. In addition, when it is not necessary to disassemble the inner cylinder 5 by the inner cylinder holding part 4c, the inner cylinder 5 may be press-fitted into the inner cylinder holding part 4c. Similarly to the outer cylinder 4, the inner cylinder 5 is set to a length that covers the stroke range of the one end 2 a of the rod 2, and the lower end of the inner cylinder 5 in FIG. 1 corresponds to the inner periphery of the outer cylinder 4. A flange portion 5a that comes into contact is provided.

  A seal ring 26 is attached to the outer periphery of the flange portion 5a, and the lower end of the outer cylinder 4 and the outer periphery of the lower end of the inner cylinder 5 are tightly sealed by the seal ring 26. A seal ring 27 is attached to the outer periphery of the upper end of the inner cylinder 5, and the inner periphery of the inner cylinder holding portion 4 c in the outer cylinder 4 and the outer periphery of the upper end side of the inner cylinder 5 are tightly sealed by this seal ring 27. Is done. Thus, the reservoir R is sealed by the seal rings 26 and 27.

  Further, in the reservoir R, annular free pistons 7 slidably inserted into the outer periphery of the inner cylinder 5 and the inner periphery of the outer cylinder 6 are slidably inserted. Is divided into an air chamber G in which the liquid is filled and a liquid chamber L in which the upper liquid in FIG. 1 is filled. The liquid chamber L formed as described above becomes a pressure chamber adjacent to the liquid chamber L through the through hole 4d formed in the small diameter portion 4a of the outer cylinder 4 and the through hole 11e formed in the rod guide 11. The rod 2 communicates with a lower pressure chamber R2 through which one end 2a of the rod 2 is inserted. That is, the liquid chamber L communicates with the pressure chamber R <b> 2 via the orifice 9. The liquid chamber L is also communicated with the air vent passage 6 through the through hole 4d. In this embodiment, the communication path 8 is formed by a part of the through hole 4d, the through hole 11e, and the air vent path 6, but is not limited thereto.

  Accordingly, the liquid chamber L applies an internal pressure to the pressures of the pressure chambers R1 and R2 via the orifice 9, and the shock absorber D is configured as a double rod type. Since there is no overall volume change in R1 and R2, basically, volume compensation at the time of piston operation is not performed, and the gas in the liquid chamber L with respect to the volume change of the liquid in the pressure chambers R1 and R2 due to temperature change. The volume is compensated by absorbing the change in volume.

  On the other hand, gas can be injected into the air chamber G through an inlet 5b that penetrates the flange 5a provided in the inner cylinder 5 in the vertical direction in FIG. The air chamber G can be sealed by being closed by a plug 28 screwed into the inlet 5b. The plurality of inlets 5b are provided in order to allow the inner cylinder 5 to be screwed to the inner cylinder holding portion 4c of the outer cylinder 4 using the inlet 5b. Only one 5b may be provided.

  When a cap 29 having an attachment portion 30 capable of attaching the shock absorber D to the vehicle is attached to the lower end of the outer cylinder 4 by screw fastening, and adjustment of the air pressure of the air chamber G is necessary, The cap 29 can be removed and the plug 28 can be easily accessed. In addition, by preparing a plurality of caps having different mounting portions according to various vehicles, the shock absorber D can be mounted on the various vehicles by performing cap replacement.

  In this embodiment, since the outer cylinder 4 covers the entire stroke range of the one end 2a of the rod 2, the rod 2 can be protected from flying objects, rain, and dust. The entire stroke range of the one end 2 a of the rod 2 may be covered in cooperation with 29 and the outer cylinder 4. When the rod 2 need not be protected, the outer cylinder 4 does not cover the entire stroke range of the one end 2a of the rod 2, and the lengths of the inner cylinder 5 and the outer cylinder 4 are set to the air chamber G and the liquid chamber. You may make it set to the length which can form L.

  Furthermore, the inside of the inner cylinder 5 is closed by the cap 29, and when the shock absorber D expands and contracts, the one end 2a of the rod 2 enters and exits into the inner cylinder 5 which is a closed space, and the atmospheric pressure in the inner cylinder 5 However, the pressure in the inner cylinder 5 acts on the rod 2, but the pressure in the inner cylinder 5 does not increase so that the pressure varies with the atmospheric pressure as a reference. The atmospheric pressure in the inner cylinder 5 does not increase so much, and the impact on the damping force generated by the shock absorber D is small and there is no particular problem. However, the cap 29 or the outer cylinder is not sealed so that the inner cylinder 5 is not sealed. 4 may be provided with a through hole leading into the inner cylinder 5 so that the inner cylinder 5 does not act as a gas spring so as to eliminate the influence on the damping force.

  Next, the operation of the shock absorber D configured as described above will be described. When the piston 3 moves upward in FIG. 1 with respect to the cylinder 1 and extends, the shock absorber D moves the liquid from the pressure chamber R1 to the pressure chamber R2 via the port 3b by the leaf valve Vb. When a piston 3 moves downward in FIG. 1 with respect to the cylinder 1 and performs compression operation, a liquid that moves from the pressure chamber R2 to the pressure chamber R1 through the port 3a is generated. A resistance is given to the flow by a leaf valve Va to generate a damping force.

  Thus, according to the buffer D comprised, since the air chamber G which pressurizes the inside of the cylinder 1 is formed between the inner cylinder 5 and the outer cylinder 6 arrange | positioned on the outer periphery of the end 2a of the rod 2. The thrust due to the pressure in the air chamber G is not applied to the rod 2.

  Therefore, according to this shock absorber D, the pressure in the air chamber G does not act on the rod 2, so that the setting of the pressure in the air chamber G is not limited, and the inside of the air chamber G that pressurizes the inside of the cylinder 1. Can be set freely, the degree of freedom in setting the damping force and response of the shock absorber D is greatly increased, and the pressure in the air chamber G is set to be optimal for the ride comfort in the vehicle. And the ride comfort in the vehicle can be dramatically improved.

  When the shock absorber D is actually assembled, the liquid chamber is inserted into the pressure chambers R1 and R2 from the upper end opening of the cylinder 1 in a state where only the rod guide 10, the seal member 15 and the cover 16 are not assembled. A liquid is injected into the L from the air vent passage 6.

  Thereafter, the rod guide 10 is fitted to the cylinder 1 and the outer cylinder 4 while the other end 2b of the rod 2 is inserted on the inner peripheral side, and the seal member 15 is laminated thereon, and finally the cover 16 is attached to the outer cylinder 4 Assembling is completed by screwing into the inner periphery of the upper end of the.

  During the liquid injection, the gas mixed in the liquid chamber L and the communication path 8 is quickly discharged out of the buffer D through the air vent path 6. Therefore, the air bleeding work in the assembly process and maintenance of the shock absorber D can be reduced, and the working time can be shortened.

  At this time, if the communication passage 8 is opened to the upper end of the liquid chamber L, the gas discharge efficiency is further improved. Therefore, in the present embodiment, the through hole 4d that communicates the air vent passage 6 and the liquid chamber L is provided so as to penetrate the small diameter portion 4a in the axial direction, and opens to the upper end of the liquid chamber L. ing. The gas in the pressure chamber R2 is discharged out of the cylinder 1 through the through hole 10c of the rod guide 10.

  Further, since the through hole 4d is connected to the air vent passage 6 so as to be visible from the vertical direction, the gas in the liquid chamber L can be quickly discharged to the air vent passage 6.

  In addition, even if bubbles are generated in the liquid in the liquid chamber L after the assembly of the shock absorber D is finished, the air is guided to the air vent passage 6 and the gas is discharged above the air vent passage 6. It is possible to prevent gas from being mixed into the pressure chambers R1 and R2 simply by accumulating.

  Furthermore, since the relief portion 11f is provided on the outer periphery of the lower end of the large diameter portion 11a of the rod guide 11 so as not to close the through hole 4d, the difference between the inner diameter of the outer cylinder 4 and the outer diameter of the cylinder 1 is not increased. The gas in the liquid chamber L can be quickly discharged to the air vent passage 6. In other words, the outer diameter of the shock absorber D can be reduced while the inner diameter of the cylinder 1 is ensured, and the size can be reduced without causing the damping force of the shock absorber D to be insufficient. If the shape of the relief portion 11f is a tapered surface, the escape portion 11f can be guided to the air vent passage 6 without further hindering gas movement.

  Moreover, since the member which slides frequently is not slidably contacted with the outer cylinder 4, the outer cylinder 4 can be formed with aluminum and the buffer D can be reduced in weight.

  Furthermore, the pressure in the air chamber G can be applied to the seal members 15 and 17 that seal the outer periphery of the rod 2 via the pressure chambers R1 and R2, and the rod 2 and the seal member are set by setting the pressure in the air chamber G. 15 and 17 can be tuned. Particularly, the damping force generated by the shock absorber D can be increased by increasing the frictional force between the rod 2 and the seal members 15 and 17. By superimposing frictional force on the cylinder, the damping force when the piston 3 moves with respect to the cylinder 1 is low, and the damping force can be increased, and the behavior of rolling, pitching, squat, etc. of the vehicle body can be suppressed firmly. It becomes like this.

  Further, even when the diameter of the rod 2 has to be increased, the volume of the air vent passage 6 formed on the outer peripheral side of the cylinder 1 from which the rod 2 does not enter and exit is also part of the reservoir R. Since it can be used, the entire volume of the liquid chamber L and the air chamber G can be secured without being affected by the diameter of the rod 2, and the overall length of the shock absorber D is not increased. Mountability is not deteriorated.

  Furthermore, since the shock absorber D can be connected to the vehicle body and axle of the vehicle via the outer cylinder 4, it is possible to avoid the lateral force and axial force acting directly on the cylinder 1, and the outer cylinder 4 can be connected to the rod. By covering the stroke range of the one end 2a of 2, the smooth sliding surface of the outer periphery of the rod 2 can be protected from flying stones, mud and the like.

  Further, in the case of this embodiment, since the open end of the outer cylinder 4 is closed by the cap 29, it is possible to reliably prevent the stepping stones, mud and the like from directly interfering with the rod 2, and the rod 2 is reliably protected. It becomes.

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

  The shock absorber of the present invention can be used for vibration control of vehicles.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Rod 2a Rod one end 2b Rod other end 3 Piston 3a, 3b Piston port 4 Outer cylinder 4a Outer cylinder small diameter part 4b Outer cylinder rod guide fitting part 4c Outer cylinder inner cylinder holding part 4d Outer cylinder Through hole 5 in the inner cylinder 5a The flange 5b in the inner cylinder 6 The inlet 6 in the inner cylinder 6 The air vent passage 7 The free piston 8 The communication passage 9 The orifice 10, 11 Rod guide 10a, 11b The fitting portion 10b in the rod guide The step portion in the rod guide 10c Through hole 11a in the rod guide Large diameter portion 11c in the rod guide 11c Outer tube fitting portion 11d in the rod guide Through hole 11e in the rod guide 11f through hole in the rod guide 12, 13 Relief portions in the rod guide 14, 24, 26, 27 Seal ring 15, 1 Seal member 15a, 17a Lip part 15b, 17b in seal member Peripheral seal part 16 in seal member Cover 25 Plug 28 Plug 29 Cap 30 Cap attachment part D Buffer G Air chamber L Liquid chamber R Reservoir R1, R2 Pressure chamber Va, Vb leaf valve

Claims (6)

A double rod type comprising a cylinder, a rod that is movably inserted into the cylinder, and a piston that is slidably inserted into the cylinder and that separates the two pressure chambers. In the shock absorber to be set, an annular reservoir is formed between the outer cylinder that covers the cylinder and forms an air vent passage between the cylinder and the outer circumference of one end of the rod protruding from the cylinder. An inner cylinder, an annular free piston that slidably contacts the outer circumference of the inner cylinder and the inner circumference of the outer cylinder, and that divides the reservoir into an air chamber and a liquid chamber, and a pressure chamber adjacent to the liquid chamber and the liquid chamber, A shock absorber comprising: a communication path that communicates with each other; and an orifice provided in the middle of the communication path, wherein the liquid chamber communicates with the air vent path. The outer cylinder has a small-diameter portion on the inner periphery, holds the inner cylinder at the small-diameter portion, and communicates the liquid chamber and the air vent passage with a through-hole penetrating the small-diameter portion along the axial direction. The shock absorber according to claim 1, wherein a communication path is formed in a rod guide that is sandwiched between the small diameter portion and slidably supports one end of the rod. The rod guide that pivotally supports one end of the rod includes a large-diameter portion that abuts on one end of the cylinder, and a relief portion is provided on the outer periphery of the small-diameter side end of the large-diameter portion. The shock absorber described in 1. The shock absorber according to claim 2 or 3, wherein the communication passage opens from a pressure chamber side end portion of a rod guide that pivotally supports one end of the rod and communicates with a large diameter portion. The shock absorber according to any one of claims 1 to 4, wherein the outer cylinder is made of aluminum. The shock absorber according to any one of claims 1 to 5, wherein the outer cylinder covers a stroke range of one end of the rod.

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