JP5476249B2 - Double cylinder type shock absorber - Google Patents

Description

  The present invention relates to a double cylinder type shock absorber.

  Various proposals have been made for the double-cylinder shock absorber so far. For example, Patent Documents 1 and 2 disclose a conventional double-cylinder type that is interposed between a vehicle body and an axle of a vehicle to suppress vehicle body vibration. A shock absorber configuration is disclosed.

  As shown in FIG. 1 of Patent Document 1, the double-cylinder shock absorber described in Patent Document 1 is held by a cylinder that accommodates a working fluid, a rod that can be freely inserted and retracted into the cylinder, and the rod. A piston slidably inserted into the cylinder; and a base member fitted to the bottom of the cylinder.

  Further, the double cylinder type shock absorber includes an outer cylinder that covers the cylinder and forms a reservoir chamber between the cylinder and the cylinder and the outer cylinder to form a double pipe.

The multi-cylinder shock absorber includes damping force generating means for attenuating the protrusions and depressions of the rod, that is, the expansion and contraction motion of the double-cylinder shock absorber, when a vibration is input.

  In the cylinder, two working chambers are formed by a piston, and the damping force generating means is formed in a communication path and a base member that are formed in the piston and communicates the two working chambers. It is provided in the middle of the communication path that communicates with the chamber.

  Since the damping force generating means generates resistance when the working fluid passes through the communication passages and suppresses the sliding of the piston, the double cylinder type shock absorber can suppress the vehicle body vibration. .

  The multi-cylinder shock absorber is generally assembled by fixing an outer cylinder and a cylinder to a bottom member connected to an axle, and the outer cylinder and the cylinder are generally made of iron.

  Further, the double cylinder type shock absorber shown in FIG. 5 of Patent Document 2 has the same basic structure as the double cylinder type shock absorber described in Patent Document 1, and an inner cylinder is provided between the cylinder and the outer periphery. An anti-roll hydraulic shock absorber in which a flow path is formed between the cylinder and the inner cylinder.

  As shown in FIGS. 5 and 6 of the above-mentioned Patent Document 2, the multi-cylinder shock absorbers form a triple pipe by a cylinder made of iron, an inner cylinder and an outer cylinder, respectively, and the cylinder, the inner cylinder and the outer cylinder each have a bottom. It is fixed to the member.

JP 2009-036258 A JP 2001-088529 A

  The conventional double cylinder type shock absorber is not particularly defective in terms of function, but it is desired to improve the following problems.

  First, since the cylinder, the inner cylinder, and the outer cylinder are separately manufactured and assembled, the number of parts is large and the assembling work is complicated.

  Second, since the cylinder, inner cylinder and outer cylinder are made of iron, it is common to increase the weight of the double-cylinder shock absorber and to coat the outer cylinder in order to improve rust prevention performance. The environmental impact is large.

  Third, the cylinder, the inner cylinder, and the outer cylinder are cylinders, and spaces are formed between the cylinders. Therefore, when the cylinder, the inner cylinder, and the outer cylinder are formed of synthetic resin, strength is ensured. It is necessary to form the cylinder and the outer cylinder thick, which leads to an increase in the diameter of the double cylinder type shock absorber.

  Therefore, an object of the present invention is to provide a double cylinder type shock absorber capable of solving the above-mentioned problems.

Hand stage for solving the above problems, a cylinder for housing a working fluid, a piston partitioning the two extension side working chamber and the compression side working chamber is slidably inserted into the cylinder in the cylinder to form a rod for holding the piston, a cylindrical inner tube forming the flow path between the cylinder covers the cylinder, a reservoir chamber between the inner cylinder covers the inner cylinder an outer cylinder, a bottom member for sealing the axially lower side open end of the outer tube, the twin-tube type shock absorber and a damping force generating means for generating a predetermined damping force when the piston slides , connecting the said cylinder and the inner cylinder,及 beauty with a bridging member for connecting the said inner tube and the outer tube, the cylinder and the inner cylinder,及 beauty the inner tube and the outer tube and the cross member Are integrally formed of synthetic resin and Via a first communication passage provided in the bottom member, twin-tube type shock absorber, characterized in that communicating the flow passage and the reservoir chamber.

According to the present invention, since the cylinder and the inner cylinder, and the inner cylinder and the outer cylinder are integrally formed via the bridging member, it is possible to reduce the number of parts and facilitate the assembling work.

Further, in the present invention, it is possible to reduce the weight of the multi-cylinder shock absorber by forming the cylinder and the inner cylinder and the inner cylinder and the outer cylinder from synthetic resin.

  Further, in the present invention, when the outer cylinder is formed of a synthetic resin, the synthetic resin material does not need to be coated for rust prevention on the outer cylinder, and the environmental load can be reduced.

In addition, by providing a bridging member, the strength of the cylinder and the inner cylinder, and the inner cylinder and the outer cylinder are increased, and even when formed of a synthetic resin, the thickness of the cylinder and the outer cylinder is reduced and the double cylinder type shock absorber is provided. It becomes possible to form a small diameter.

It is a longitudinal cross-sectional principle figure of the double cylinder type buffer which concerns on the reference example of this invention. (A) It is a perspective view which shows the cylinder and outer cylinder composite_body | complex in the double cylinder type buffer which concerns on the reference example of this invention. (B) It is XX sectional drawing which shows the cylinder and outer cylinder composite_body | complex in the double cylinder type buffer which concerns on one embodiment of this invention. It is a cross-sectional view which shows the modification of the cylinder and outer cylinder composite_body | complex in the double cylinder type shock absorber which concerns on the reference example of this invention. It is a longitudinal cross-sectional principle figure of the double cylinder type buffer which concerns on one embodiment of this invention. It is a cross-sectional view showing a modification of the cylinder / inner cylinder / outer cylinder composite in the double cylinder type shock absorber according to one embodiment of the present invention.

A double cylinder type shock absorber showing a reference example of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

As shown in FIG. 1, a double-cylinder shock absorber according to a reference example includes a cylinder 1 that contains a working fluid, and two working chambers that are slidably inserted into the cylinder 1. A piston 2 that partitions A and B , a rod 3 that holds the piston 2, an outer cylinder 4 that covers the cylinder 1 and forms a reservoir chamber R between the cylinder 1, and sliding of the piston 2 And a damping force generating means (V1, V2) for generating a predetermined damping force.

  As shown in FIG. 2, the double cylinder type shock absorber includes a bridging member 5 that couples the cylinder 1 and the outer cylinder 4, and synthesizes the cylinder 1, the outer cylinder 4, and the bridging member 5. It is formed integrally with resin.

  Below, each component of the said double cylinder type shock absorber is demonstrated in detail.

  The multi-cylinder shock absorber is interposed between a vehicle body and an axle in a vehicle and suppresses vehicle body vibration.

  The rod 3 protruding and retracting in the cylinder 1 is slidably supported on the inner periphery of an annular rod guide 10 provided at the head portion (upper end in the figure) of the cylinder 1, and the upper end part in the figure is attached to the vehicle body side mounting member. It is fixed to the vehicle body via (not shown).

Further, a bottom member 11 for sealing the lower opening in the figure of the outer cylinder is provided at the bottom part (lower end in the figure) of the outer cylinder that covers the cylinder, and the bottom member 11 is an axle side mounting member ( (Not shown) and fixed to the axle.

  By providing the above configuration, the multi-cylinder shock absorber is interposed between the vehicle body and the axle, and expands and contracts when the rod 3 moves in and out of the cylinder 1 by the input of road surface vibration.

  Further, a cap member 12 is provided at the upper end opening of the outer cylinder 4 in the figure, and this cap member 12 is provided with an annular seal member 13 slidably contacting the outer periphery of the rod 3, and the figure of the outer cylinder 4. The middle upper end opening is sealed to prevent the working fluid stored in the double cylinder type shock absorber together with the bottom member 11 from leaking to the outside.

  The cylinder 1 covered with the outer cylinder 4 is disposed coaxially with the outer cylinder 4, and a reservoir chamber R is formed between the outer cylinder 4 and the cylinder 1, and a working fluid is contained in the reservoir chamber R. Is stored, and an air chamber G that is set to a predetermined internal pressure is formed upward via the liquid level O.

  The cylinder 1 has a rod guide 10 fitted in the upper end opening in the figure and a base member 14 fitted in the lower end opening in the figure. Two working chambers A and B are partitioned, and an extension working chamber A is formed on the rod 3 side, and a compression working chamber B is formed on the piston 2 side.

  The piston 2 has expansion side and pressure side communication passages L1 and L2 communicating with the two working chambers A and B, and is held at the tip of the rod 3 connected to the vehicle body side. The cylinder 1 is slid in response to road surface vibration.

  An extension side leaf valve V1 is provided in the middle of the extension side communication passage L1 so that the extension side leaf valve V1 can be opened and closed. The extension side leaf valve V1 has a working fluid that passes through the extension side communication passage L1. While only allowing movement from A to the pressure side working chamber B, resistance is generated during the movement to generate an expansion-side damping force.

  On the other hand, in the middle of the pressure side communication passage L2, a check valve C1 is provided so as to be openable and closable. The check valve C1 is configured such that the working fluid passing through the pressure side communication passage L2 is expanded from the pressure side working chamber B. Only movement to the room A is permitted, and the movement is not hindered.

  Further, the base member 14 fitted to the bottom portion of the cylinder 1 has expansion side and pressure side communication passages L3 and L4 that communicate the pressure side working chamber B and the reservoir chamber R, and is supported by the bottom member 11. Become.

  A check valve C2 is provided in the middle of the expansion side communication path L3 of the base member 14 so that the working fluid passing through the expansion side communication path L3 is stored in the reservoir chamber R. Only the movement to the compression side working chamber B is allowed, and the movement is not hindered.

  On the other hand, in the middle of the pressure side communication passage L4 in the base member 14, a pressure side leaf valve V2 is provided so as to be openable and closable, and the pressure side leaf valve V2 is operated by the working fluid passing through the pressure side communication passage L4. Only the movement from the chamber B to the reservoir chamber R is allowed, and resistance is generated during the movement to generate a compression-side damping force.

  In other words, the expansion side leaf valve V1 attached to the piston 2 and the compression side leaf valve V2 attached to the base member 14 constitute a damping force generating means. It becomes possible for the working fluid to pass through V1 and V2 to generate a predetermined damping force.

  Further, the double cylinder type shock absorber can supplement the reservoir chamber R with the working fluid that is insufficient and insufficient for the rod 3 to protrude into and out of the cylinder 1 through the base member 14.

  By providing the above-described configuration, when the double-tube shock absorber extends, the expansion side working chamber A is pressurized and the working fluid passes through the expansion side leaf valve V1 and moves to the compression side working chamber B. A working fluid that generates a damping force and is insufficient in the cylinder 1 as the rod 3 moves out flows from the reservoir chamber R into the pressure side working chamber via the check valve C2 of the base member 14.

  On the other hand, when the double cylinder type shock absorber contracts, the pressure side working chamber B is pressurized and the working fluid moves from the pressure side working chamber B to the extension side working chamber A via the check valve C1 of the piston, and the rod 3 is immersed. The surplus working fluid in the minute cylinder 1 passes through the pressure-side leaf valve V2 and moves to the reservoir chamber R to generate a pressure-side damping force.

  The configuration of the damping force generating means is not limited to the above, and other known configurations can be selected.

In the reference example , as shown in FIG. 2, the multi-cylinder shock absorber includes a bridging member 5 that couples the cylinder 1 and the outer cylinder 4, and the cylinder 1, the outer cylinder 4, and the bridging member 5 are The cylinder / outer cylinder composite H1 is formed integrally with a synthetic resin.

  In FIG. 2B, for the sake of explanation, the boundary between the cylinder 1 and the bridging member 5 and the boundary between the bridging member 5 and the outer cylinder 4 are indicated by broken lines, which are imaginary lines.

  This cylinder / outer cylinder composite H1 is formed in a cylindrical shape by injection molding, extrusion molding, or the like, and has a columnar hollow portion 6 positioned at the axial center portion, a hexagonal cross section and a cross section that penetrate the wall thickness in the axial direction. A substantially rectangular shaft through hole 7 is provided.

  When the double cylinder type shock absorber is assembled, the inner circumferential surface of the cylinder / outer cylinder complex H1 is the cylinder inner circumferential surface 1a, the outer circumferential surface of the cylinder / outer cylinder complex H1 is the outer cylindrical outer circumferential surface 4a, and the hollow portion 6 is the inside of the cylinder 1 (A, B), and the shaft through hole 7 is the reservoir chamber R.

  In other words, by providing the bridging member 5 and making the cylinder 1 and the outer cylinder 4 the cylinder / outer cylinder composite H1, it is not necessary to assemble the cylinder 1 and the outer cylinder 4 as in the prior art, reducing the number of parts. It becomes possible to facilitate the assembly work of the double cylinder type shock absorber.

  Further, by forming the cylinder / outer cylinder composite H1 with synthetic resin, it is possible to reduce the weight as compared with the conventional double cylinder type shock absorber in which the cylinder 1 and the outer cylinder 4 are formed of metal such as iron. It becomes.

  In addition, the synthetic resin does not need to be coated for rust prevention on the outer cylinder 4 and can reduce the environmental load.

  Further, by providing the bridging member 5, the strength of the cylinder 1 and the outer cylinder 4 in the cylinder / outer cylinder composite H1 is increased, and the cylinder is compared with the case where the conventional cylinder 100 and the outer cylinder 400 are formed of synthetic resin. It is possible to reduce the wall thickness of the outer cylinder 4 and the outer cylinder 4 to form a double cylinder type shock absorber with a small diameter.

  In order to make the strength of the cylinder / outer cylinder composite H1 uniform, it is preferable to form the shaft through holes 7 at equal intervals on the circumference concentric with the cylinder 1, but the shapes of the shaft through holes 7 and the bridging member 5 are the same. Can be appropriately selected.

  Further, in order to ensure the slidability of the piston 2, as shown in FIG. 3, a cylindrical member T made of iron or aluminum is inserted into the inner peripheral surface of the cylinder / outer cylinder composite H1, that is, the cylinder inner peripheral surface 1a. It may be provided by molding, and the cylindrical member T may ensure the slidability of the piston 2.

  In this case, the cylindrical member T may be provided only on the piston sliding surface, or may be provided on the entire inner peripheral surface of the cylinder / outer cylinder composite H1.

  Similarly, since the cylindrical member T is reinforced by the bridging member 5, it is possible to reduce the wall thickness compared to the conventional cylinder 100, so that the weight reduction of the multi-cylinder shock absorber may be hindered. Absent.

  The material of the cylindrical member T is not limited to the above, and other materials such as other metals or synthetic resins can be appropriately selected as long as the slidability of the piston 2 can be ensured.

Next, twin-tube type shock absorber of an embodiment of the present invention will be described with reference to the drawings. About the structure corresponding to a reference example , the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 4, the double-cylinder shock absorber according to the present embodiment includes a cylinder 1 that contains a working fluid, and two working chambers that are slidably inserted into the cylinder 1. A piston 2 that partitions A and B; a rod 3 that holds the piston 2; a cylindrical inner cylinder 8 that covers the cylinder 1 and forms a flow path L between the cylinder 1; and the inner cylinder And an outer cylinder 4 that forms a reservoir chamber R between the inner cylinder 8 and a damping force generating means (V3) that attenuates the sliding of the piston 2.

  As shown in FIG. 5, the cylinder 1, the inner cylinder 8, and the outer cylinder 4 are provided with a bridging member 5, and the cylinder 1, the inner cylinder 8, the outer cylinder 4, and the bridging member 5 are provided. It is formed integrally with a synthetic resin.

The multi-cylinder shock absorber is interposed between the vehicle body and the axle in the vehicle, as in the above reference example, and suppresses vehicle body vibration.

  In the present embodiment, an inner cylinder 8 is provided coaxially between the cylinder 1 and the outer cylinder 4, a flow path L is formed between the inner cylinder 8 and the cylinder 1, and a uniflow structure is achieved. This is different from the above-described embodiment.

The flow path L communicates with the extension side working chamber A via the second communication passage L5 formed in the rod guide 10, further reservoir chamber R via the first communication passage L6 which is formed in the base member 14 Communicate with.

In the middle of the first series passage L6 formed in the base member 14, only the movement of the working fluid from the flow path L to the reservoir chamber R is allowed, and a leaf serving as a damping force generating means that generates resistance during the movement is provided. A valve V3 is provided.

The piston 2 is slidably inserted in the cylinder 1, made in the fourth communication passage L7 for communicating the extension side working chamber A and the compression side working chamber B through the piston 2 is formed, the first A check valve C3 that allows only the movement of the working fluid from the pressure side working chamber B to the extension side working chamber A and does not hinder the movement is provided in the middle of the four- way passage L7.

Further, the base member 14 is made by a third communication passage L8 is formed for communicating the compression side working chamber B and the reservoir chamber R, the middle is the third communication passage L8, the compression side working chamber from the reservoir chamber R A check valve C4 that allows only the movement of the working fluid to B and does not hinder the movement is provided.

By providing the above configuration, when the multi-cylinder shock absorber according to the present embodiment expands, the working fluid in the expansion side working chamber A to be pressurized is stored in the reservoir via the second communication path L5 and the flow path L. In order to move into the chamber R, a predetermined damping force is generated through the leaf valve V3.

  At this time, the working fluid that is deficient in the cylinder 1 for the withdrawal of the rod 3 flows from the reservoir chamber R into the pressure-side working chamber B via the check valve C4 of the base member 14.

  Further, when the double cylinder type shock absorber according to the present embodiment contracts, the working fluid in the pressure side working chamber B to be pressurized moves into the expansion side working chamber A by opening the check valve C3 of the piston 2.

  Then, when the working fluid that is the surplus volume of the rod 3 that is immersed in the cylinder 1 moves into the reservoir chamber R through the flow path L, it passes through the leaf valve V3 and generates a predetermined damping force.

  In the present embodiment, the multi-cylinder shock absorber includes a bridging member 5 that couples the cylinder 1, the inner cylinder 8, and the outer cylinder 4, and the cylinder 1, the inner cylinder 8, the outer cylinder 4, and the bridging member. The member 5 is integrally formed of a synthetic resin to constitute a cylinder / inner cylinder / outer cylinder composite H2.

  In FIG. 5, for explanation, from the inner peripheral side of the cylinder / inner cylinder / outer cylinder complex H <b> 2, the boundary between the cylinder 1 and the bridging member 5, the boundary between the bridging member 5 and the inner cylinder 8, and the inner cylinder 8 and bridging. The boundary between the member 5 and the boundary between the bridging member 5 and the outer cylinder 4 are indicated by broken lines, and each broken line is an imaginary line.

  The cylinder / inner cylinder / outer cylinder composite H2 is formed into a cylindrical shape by injection molding, extrusion molding, or the like, and has a columnar hollow portion 60 positioned in the axial center portion and a plurality of thicknesses penetrating in the axial direction. A shaft through hole 70 is provided.

  The shaft through hole 70 includes an outer peripheral side shaft through hole 70a formed along the outer peripheral surface and an inner peripheral side shaft through hole 70b formed along the inner peripheral surface.

  When the multi-cylinder shock absorber is assembled, the inner peripheral surface of the cylinder / inner cylinder / outer cylinder complex H2 is the cylinder inner peripheral surface 1a, the hollow portion 60 is the inside of the cylinder (A, B), and the outer peripheral side shaft. The through hole 70a serves as a reservoir chamber R, and the inner peripheral side shaft through hole 70b serves as a flow path.

  That is, the cylinder 1, the inner cylinder 8 and the outer cylinder 4 are made the cylinder / inner cylinder / outer cylinder composite H2 by the bridging member 5, so that the cylinder 1, the inner cylinder 8 and the outer cylinder 4 are respectively connected as in the conventional case. There is no need to assemble, and the number of parts can be reduced to facilitate the assembly work of the double cylinder type shock absorber.

  In addition, by forming the cylinder / inner cylinder / outer cylinder composite H2 from a synthetic resin, the cylinder 1, the inner cylinder 8 and the outer cylinder 4 are compared with a conventional multi-cylinder shock absorber formed of a metal such as iron. And can be reduced in weight.

  In addition, the synthetic resin does not need to be coated for rust prevention on the outer cylinder 4 and can reduce the environmental load.

  Further, by providing the bridging member 5, the strength of the cylinder 1, the inner cylinder 8 and the outer cylinder 4 in the cylinder / inner cylinder / outer cylinder composite H2 is increased, and the conventional cylinder 100, inner cylinder 800 and outer cylinder are made of synthetic resin. Compared with the case where 400 is formed, it is possible to reduce the thickness of the cylinder 1, the inner cylinder 8, and the outer cylinder 4 to form a double cylinder type shock absorber with a small diameter.

As in the above reference example , it is preferable to form the shaft through holes 70 uniformly in the circumferential direction, and the shapes of the shaft through holes 70 and the bridging member 5 can be appropriately selected.

Although not shown, the effect of insert-molding the cylindrical member T is the same as that of the reference example .

Similarly, although not shown, the configuration of the cylinder / inner cylinder / outer cylinder complex H2 according to the present embodiment is not limited to the above, and a plurality of shaft through holes 7 of the cylinder / outer cylinder complex H1 in the reference example are formed. However, one of the through holes may be used as the flow path L of the present embodiment.

  In this case, it is possible to further reduce the diameter of the double-tube shock absorber having a flow path on the outer periphery of the cylinder.

  In the above embodiment, the cylinder / inner cylinder / outer cylinder composite H2 is used. However, the present invention is not limited to this. Even if a conventional outer cylinder is used by forming a cylinder / inner cylinder composite, the inner cylinder / A conventional cylinder may be used by forming an outer cylinder composite.

  It is of course possible to use the cylinder / inner cylinder / outer cylinder composite H2 according to the present embodiment in the anti-roll hydraulic shock absorber disclosed in Patent Document 2.

  While the preferred embodiment of the present invention has been described above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

  For example, in the above-described embodiment, the double cylinder type shock absorber interposed between the vehicle body and the axle in the vehicle is used. However, in addition to the vehicle, a double cylinder type shock absorber having the above-described configuration of the present invention may be used. Of course it is good.

  Further, the structure of the valve structure and the communication path for generating the damping force in the double-tube shock absorber is not limited to the above, and any other double-tube shock absorber having a double-tube or triple-tube structure can be used. Of course, the cylinder / outer cylinder composite H1 and the cylinder / inner cylinder / outer cylinder composite H2 may be used.

  Moreover, in the said embodiment, although the triple pipe which consists of a cylinder and an outer cylinder, the triple pipe which consists of a cylinder, an inner cylinder, and an outer cylinder was demonstrated, you may utilize this invention for the pipe | tube more than quadruple.

A Stretching side working chamber B Pressure side working chamber C1, C2, C3, C4 Check valves V1, V2, V3 Leaf valve (damping force generating means)
H1 Cylinder / outer cylinder complex H2 Cylinder / inner cylinder / outer cylinder complex L Flow path L1, L2, L3, L4 Communication path
L5 second communication passage
L6 1st passage
L7 4th passage
L8 Third communication path R Reservoir chamber 1 Cylinder 2 Piston 3 Rod 4 Outer cylinder 5 Bridge member 6, 60 Hollow part 7, 70 Shaft through hole 8 Inner cylinder

Claims (5)

A cylinder containing a working fluid;
A piston that is slidably inserted into the cylinder and divides the two working chambers and the compression working chamber into the cylinder;
A rod for holding the piston;
A cylindrical inner cylinder that covers the cylinder and forms a flow path with the cylinder;
An outer cylinder that covers the inner cylinder and forms a reservoir chamber with the inner cylinder;
  A bottom member for sealing the axially lower open end of the outer cylinder;
In a double cylinder type shock absorber comprising a damping force generating means for generating a predetermined damping force when the piston slides,
A bridging member for coupling the cylinder and the inner cylinder, and for coupling the inner cylinder and the outer cylinder;
The cylinder and the inner cylinder, and the inner cylinder, the outer cylinder, and the bridging member are integrally formed of a synthetic resin, and the flow path is formed through a first series passage provided in the bottom member. A multi-cylinder shock absorber communicating with the reservoir chamber. 2. The double cylinder type shock absorber according to claim 1, wherein a cylindrical member is provided on the piston sliding surface of the cylinder by insert molding into the cylinder.
The cylinder, the inner cylinder, the outer cylinder, and the bridging member are integrally formed to form a cylindrical cylinder / inner cylinder / outer cylinder composite. 3. The multi-cylinder shock absorber according to claim 1, wherein a plurality of shaft through holes that penetrate the thickness of the body in the axial direction are formed, and the shaft through holes serve as the flow path and the reservoir chamber. .
The double cylinder type shock absorber according to claim 3, wherein the shaft through holes are formed at equal intervals on a circumference concentric with the cylinder.
  A rod guide is provided at the axially upper opening end of the outer cylinder,
  A second communication path provided in the rod guide communicating the flow path and the extension side working chamber;
  5. The multi-cylinder shock absorber according to claim 1, further comprising a third communication passage provided in the bottom member that communicates the pressure side working chamber and the reservoir chamber.

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