JP6489977B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber used for a railway vehicle or the like.

  Patent Document 1 is disclosed as a prior art of a damping force generating structure provided in a shock absorber. That is, in the damping force generation structure of Patent Document 1, a collar member is provided in a through hole provided in a valve case that partitions a lower oil chamber inside a cylinder and a reservoir chamber outside the cylinder, and a spiral groove is formed on the outer peripheral surface of the collar member. Is forming. Thereby, the orifice characteristic in the low speed region of the piston is set as a linear characteristic (choke characteristic) to ensure the operability.

  Therefore, a railway vehicle has conventionally been provided with a railcar shock absorber having a valve mechanism (control valve and relief valve) (see, for example, Patent Document 2). When the damping force generating structure 1 is applied, the control valve has a flow path characteristic that approaches a linear characteristic proportional to the piston speed by the spiral groove. From this flow path characteristic (control valve), the valve characteristic (relief valve) The problem remains that there is no degree of freedom in damping force characteristics when moving to.

JP-A-11-166574 JP2013-137042A

  In view of the above-described problems, the present invention has a degree of freedom in the damping force characteristic at the time of transition from the flow path characteristic to the valve characteristic, that is, the damping force characteristic that can smoothly transition from the flow path characteristic to the valve characteristic. It aims at providing the buffer which has this.

  As means for solving the above problems, a first shock absorber according to the present invention includes a cylinder in which a working fluid is sealed, and a piston that is inserted into the cylinder and divides the inside of the cylinder into two chambers. A piston rod connected to the piston and extending outward from the cylinder; a flow path in which a working fluid flows by sliding of the piston in the cylinder; and a movement of the piston provided in the flow path And a valve mechanism for adjusting the flow of the working fluid passing through the flow path, the valve mechanism being movable into a valve body housing chamber formed in the flow path. A valve body that opens and closes the flow path, and spring means that biases the valve body in a direction to close the flow path, and the valve body slides in the flow path. A sliding shaft portion, and an outer wall surface of the sliding shaft portion and the flow path A spiral passage that communicates the upstream side and the downstream side of the flow path via the valve body is provided between the inner wall surface and the working fluid that flows through the spiral passage as the valve body moves. The flow path length changes.

The second shock absorber according to the present invention includes a cylinder in which a working fluid is sealed, a piston that is inserted into the cylinder and divides the cylinder into two chambers, and is connected to the piston. A piston rod extending from the cylinder to the outside, a flow path in which a working fluid flows by sliding of the piston in the cylinder, and the flow path provided in the flow path and passing through the flow path as the piston moves And a valve mechanism that adjusts the flow of the working fluid, wherein the valve mechanism is movably accommodated in a valve body housing chamber formed in the flow path, and the flow path is A valve body that opens and closes, and a spring means that urges the valve body in a direction to close the flow path,
The valve body has an inner passage that extends through the valve body so as to communicate the upstream side and the downstream side of the flow path, and slides in the inner passage into the valve body housing chamber. Provided with a sliding shaft portion, a spiral passage that communicates the upstream side and the downstream side of the flow path via the valve body between the outer wall surface of the sliding shaft portion and the inner wall surface of the inner passage. The flow path length of the working fluid flowing through the spiral passage is changed with the movement of the valve body.

  In the shock absorber according to the present invention, it is possible to generate a damping force characteristic that can smoothly shift from the flow path characteristic to the valve characteristic.

FIG. 1 is a cross-sectional view showing a shock absorber according to the first embodiment. FIG. 2 is a cross-sectional view of the valve mechanism provided in the shock absorber according to the first embodiment. FIG. 3 is a side view of a valve body provided in the valve mechanism of FIG. FIG. 4 is a damping force characteristic diagram of the valve mechanism of FIG. FIG. 5 is a cross-sectional view of the valve mechanism provided in the shock absorber according to the second embodiment. FIG. 6 is a damping force characteristic diagram of the valve mechanism of FIG.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to FIGS.
The shock absorbers 1a and 1b according to the first and second embodiments, which will be described below, are employed as railway vehicle yaw dampers that are mounted horizontally between the carriage and the vehicle body. In this embodiment, a railway vehicle yaw damper mounted in a horizontal state is shown as an example, but it may be used for a left-right motion damper or a vertical motion damper.
First, the shock absorber 1a according to the first embodiment will be described with reference to FIGS.
As shown in FIG. 1, the shock absorber 1 a according to the first embodiment includes an outer cylinder 2 and a cylinder 3 arranged concentrically with the outer cylinder 2. Openings at both ends of the outer cylinder 2 and the cylinder 3 are closed by a rear end plate 5 and a front end plate 4, respectively. An annular reservoir chamber 6 is formed between the inner wall surface of the outer cylinder 2 and the outer wall surface of the cylinder 3.
For convenience of explanation, the following description will be made with the left side in the figure (when the sign is viewed upright; the same applies hereinafter), that is, the bracket 13 side as the front side and the right side in the figure, that is, the bracket 14 side as the rear side.

  The rear end plate 5 has a divided structure including a main lid member 11 that closes the rear end opening of the outer cylinder 2 and a sub lid member 12 that closes the rear end opening of the cylinder 3. The main lid member 11 is fixedly provided with a connecting bracket 14 that is connected to the vehicle body side. On the other hand, the front end plate 4 is configured as a rod guide that closes the front end openings of the outer cylinder 2 and the cylinder 3 and also has a guide function for the piston rod 16.

  A piston 15 is disposed in the cylinder 3 so as to be slidable in the axial direction. One end (rear end) of a piston rod 16 is connected to the piston 15, and the other end (front end) of the piston rod 16 is inserted through a front end plate (rod guide) 4 in a liquid-tight manner. It extends to the outside of the tube 2. Note that a connecting bracket 13 is fixed to the other end portion of the piston rod 16 to be connected to the carriage side.

  The inside of the cylinder 3 is divided into a rod side oil chamber 18 and an anti-rod side oil chamber 19 by a piston 15. The rod-side oil chamber 18 and the anti-rod-side oil chamber 19 are filled with working oil as a working fluid. The piston 15 is provided with a check valve 20 that allows only the flow of hydraulic oil from the non-rod side oil chamber 19 to the rod side oil chamber 18. Further, a check valve 21 that allows only the flow of hydraulic oil from the reservoir chamber 6 to the anti-rod-side oil chamber 19 is disposed on the sub-lid member 12 of the rear end plate 5.

  As shown in FIGS. 1 and 2, the front end plate 4 is provided with a flow path 25 that communicates the rod-side oil chamber 18 in the cylinder 3 with the reservoir chamber 6. The flow path 25 is provided with a valve mechanism 30 a that adjusts the flow of hydraulic oil that opens and closes as the piston 15 moves and passes through the flow path 25. The flow path 25 includes an upstream flow path 25a that communicates with the rod-side oil chamber 18, a recess 25b that communicates with the upstream flow path 25a and accommodates the housing 35 of the valve mechanism 30a (see FIG. 2), and the recess 25 b and a downstream flow path 25 c communicating with the reservoir chamber 6. Note that the valve mechanism 30a may be accommodated directly in the front end plate 4 without providing the housing 35 separately.

  The valve mechanism 30 a includes a housing 35 accommodated in the recess 25 b of the flow path 25, a valve body 36 a that opens and closes the flow path 25, and a direction in which the flow path 25 is closed. And a spring 37 which is a spring means for urging the spring. Specifically, the housing 35 has a block shape, and is an upstream flow hole 38 communicating with the upstream flow path 25a, and a valve that communicates with the upstream flow hole 38 and accommodates the cup-shaped main body 49 of the valve body 36a. A body housing chamber 39 and a plurality of downstream flow holes 40 communicating with the valve body housing chamber 39 and communicating with the downstream channel 25c are provided. The valve body accommodation chamber 39 of the housing 35 is formed between an accommodation recess 43 provided in the housing 35 and a closing portion 44 a provided so as to close the accommodation recess 43. The closing portion 44 a includes a plate-like base portion 46 that closes the housing concave portion 43 of the housing 35, and a support convex portion 47 that protrudes from the base portion 46 toward the valve body housing chamber 39.

  As shown in FIGS. 2 and 3, the valve body 36 a is integrally connected to a sliding shaft portion 48 that slides along the upstream flow hole 38 of the housing 35 and one end of the sliding shaft portion 48. And a cup-shaped main body portion 49. The cup-shaped main body portion 49 includes a tubular portion 51 and a plate-like portion 52 that closes one end side of the tubular portion 51. A plurality of through holes 53 penetrating in the radial direction are formed in the cylindrical portion 51 of the cup-shaped main body portion 49 at intervals along the circumferential direction. One end of the sliding shaft portion 48 is integrally connected to the plate-like portion 52 of the cup-shaped main body portion 49. The sliding shaft portion 48 is formed with an inner passage 58 concentrically extending in the axial direction with the other end opened therein. The sliding shaft 48 is formed with an opening 59 that communicates with the inner passage 58 and penetrates in the radial direction. The opening 59 is formed at a position close to the cup-shaped main body 49. A groove portion 60 that spirally extends from the outer wall surface of the sliding shaft portion 48 to a part of the outer wall surface of the cup-shaped main body portion 49 is formed. The groove portion 60 corresponds to a spiral passage that communicates the upstream flow path 25a and the downstream flow path 25c via the valve body 36a. In the present embodiment, the groove portion 60 that spirally extends is formed on the outer wall surface of the sliding shaft portion 48, but the spiral groove portion 60 may be provided on the inner wall surface of the upstream flow hole 38 of the housing 35.

  The sliding shaft portion 48 of the valve body 36a is inserted into the upstream-side flow hole 38 of the housing 35 so as to be relatively slidable. The cup-shaped body portion 49 of the valve body 36a forms the housing 35 on its open side. It arrange | positions in the valve body storage chamber 39 so that it may point to the obstruction | occlusion part 44a side to do. As a result, the valve body 36 a is movable in the valve body accommodation chamber 39 in a direction along the upstream flow hole 38 of the housing 35. Further, a spring 37 is disposed around the support convex portion 47 of the closing portion 44a between the plate-like portion 52 of the cup-shaped main body portion 49 of the valve body 36a and the base portion 46 of the closing portion 44a constituting the housing 35. Is done. Due to the biasing force of the spring 37, the cup-shaped main body portion 49 is biased in a direction away from the closing portion 44 a of the housing 35 (a direction in contact with the bottom surface of the housing recess 43 of the housing 35). 38 and eventually the flow path 25 is closed. However, since the spiral groove portion 60 is formed on the outer wall surface of the sliding shaft portion 48 of the valve body 36a, the plate-like portion 52 of the cup-like main body portion 49 abuts against the bottom surface of the housing recess 43 of the housing 35. Even in this state (the state shown in FIG. 2), the upstream channel 25a and the downstream channel 25c communicate with each other.

Next, the operation of the shock absorber 1a according to the first embodiment of the present invention will be described.
The shock absorber 1a according to the first embodiment is mounted horizontally between the carriage and the vehicle body, the bracket 13 on the piston rod 16 side is connected to the carriage, and the bracket 14 on the outer cylinder 2 side is connected to the vehicle body. Connected.

  When the carriage and the vehicle body move relative to each other in the horizontal direction, the piston rod 16 of the shock absorber 1a expands and contracts. As a result, during the extension stroke of the piston rod 16, the hydraulic oil in the rod side oil chamber 18 does not flow into the anti-rod side oil chamber 19 by the check valve 20 provided in the piston 15, so Then, the valve mechanism 30a is opened to flow into the reservoir chamber 6, and an expansion-side damping force is generated accordingly. During this extension stroke, the hydraulic oil for the withdrawal of the piston rod 16 is replenished from the reservoir chamber 6 to the anti-rod-side oil chamber 19 via a check valve 21 provided on the sub-cover member 12 of the rear end plate 5. .

  On the other hand, during the contraction stroke of the piston rod 16, the hydraulic oil in the anti-rod side oil chamber 19 flows into the rod side oil chamber 18 via the check valve 20 provided in the piston 15, and the anti-rod side oil chamber 19 and the rod side The fluid pressure in the oil chamber 18 is almost the same, and the hydraulic oil corresponding to the ingress of the piston rod 16 opens the valve mechanism 30a provided in the flow path 25 to flow into the reservoir chamber 6, and in response to this, the contraction side Damping force is generated.

  When the piston rod 16 extends and contracts, the hydraulic oil in the rod side oil chamber 18 opens the valve mechanism 30a in the flow path 30 and flows into the reservoir chamber 6. At this time, the speed of the piston 15 is increased. Is maintained in the low speed range, that is, the state in which the plate-like portion 52 of the cup-shaped main body portion 49 of the valve body 36a is in contact with the bottom surface of the housing recess 43 of the housing 35 by the urging force of the spring 37 is maintained. In the situation, the groove portion 60 provided in the sliding shaft portion 48 of the valve body 36a specifically has a groove portion 60 formed in a spiral shape so that the flow path length through which the hydraulic oil flows is as long as possible. As shown in FIG. 4, the damping force characteristic can be changed from the orifice characteristic proportional to the square of the piston speed to the flow path characteristic, and the flow path characteristic can be approximated to a linear characteristic proportional to the piston speed. it can.

Further, the speed of the piston 15 is increased, and the plate-like portion 52 of the cup-like main body portion 49 of the valve body 36 a moves away from the bottom surface of the housing recess 43 of the housing 35 against the biasing force of the spring 37. When the opening portion 59 (inner passage 58) of the shaft portion 48 begins to communicate with the valve body accommodating chamber 39, the spiral groove portion 60 provided in the sliding shaft portion 48 with hydraulic oil is moved along with the movement of the valve body 36a. Since the flow path length gradually decreases, as shown in FIG. 4, the damping force characteristic changes from the flow path characteristic (the proportional constant of the damping force to the piston speed is large) to the valve characteristic (the proportional constant of the damping force to the piston speed is When shifting to (Small), the flow path characteristic and the valve characteristic can be connected with a smooth curved line that protrudes slightly downward, without a sudden change as in the prior art.
Thereafter, when the speed of the piston 15 further increases (medium / high speed range), the opening area of the opening 59 (inner passage 58) of the sliding shaft portion 48 with respect to the valve body housing chamber 39 gradually increases, thereby reducing damping force characteristics. As a result, valve characteristics can be obtained.

  In the shock absorber 1a according to the first embodiment described above, in particular, the groove portion extending spirally on the outer wall surface of the sliding shaft portion 48 of the valve body 36a that slides along the upstream flow hole 38 of the housing 35. 60 is formed, the damping force characteristic when the piston speed is low, that is, the flow path characteristic can be brought close to a linear characteristic proportional to the piston speed. In addition, as the damping force characteristic, the flow path characteristic and the valve characteristic can be connected by a smooth curved line that slightly protrudes downward. As a result, it is possible to suppress abnormal noise (vibration sound of the valve body 36a, etc.) and a sensation that can occur at the boundary between different damping force characteristics. In addition, the shock absorber employed in the railway vehicle has a flow path characteristic in the normal region, and in the shock absorber 1a according to the first embodiment, the groove portion 60 provided on the outer wall surface of the sliding shaft portion 48 of the valve body 36a. Since the flow path characteristics are generated, the influence of wear caused by sliding between the sliding shaft portion 48 of the valve body 36a and the upstream flow hole 38 of the housing 35 is small, and the cross-sectional area of the groove portion 60 is substantially reduced. It can be kept constant and a stable damping force characteristic can be generated. Further, in the shock absorber 1a according to the first embodiment, the flow path characteristic and the valve characteristic can be generated as the damping force characteristic by the single valve mechanism 30a having a simple configuration. Therefore, the number of parts and the number of processing steps can be reduced. Can be reduced, which leads to cost reduction. In the present embodiment, the normal area is configured to be the flow path characteristic area, but the normal area may be the valve characteristic area.

Next, the shock absorber 1b according to the second embodiment will be described with reference to FIGS. When describing the shock absorber 1b according to the second embodiment, differences from the shock absorber 1a according to the first embodiment will be described.
The shock absorber 1b according to the second embodiment employs a valve mechanism 30b different from the valve mechanism 30a employed in the shock absorber 1a according to the first embodiment.
As shown in FIG. 5, the valve element 36 b of the valve mechanism 30 b is integrally connected to a sliding shaft portion 48 that slides along the upstream flow hole 38 of the housing 35 and one end of the sliding shaft portion 48. And a T-shaped main body portion 65 having a T-shaped cross section. The T-shaped main body portion 65 includes a shaft portion 66 and a disk-shaped portion 67 that is integrally connected to one end of the shaft portion 66. One end of the sliding shaft portion 48 is integrally connected to the disk-shaped portion 67 of the T-shaped main body portion 65. The outer diameter of the sliding shaft portion 48 is smaller than the outer diameter of the shaft portion 66 of the T-shaped main body portion 65. In the sliding shaft portion 48 and the T-shaped main body portion 65, an inner passage 58 extending concentrically and penetrating in the axial direction is formed. The sliding shaft 48 is formed with an opening 59 that communicates with the inner passage 58 and penetrates in the radial direction. The opening 59 is formed at a position close to the T-shaped main body 65. The upstream flow path 25a and the downstream flow path 25c are communicated by the inner passage 58 provided in the valve body 36b.

  The valve body accommodation chamber 39 of the housing 35 is formed between an accommodation recess 43 provided in the housing 35 and a closing portion 44 b provided so as to close the accommodation recess 43. The closing portion 44b is provided so as to project from the base portion 46 toward the valve body housing chamber 39 and close to the inside passage 58 of the valve body 36b. And a sliding shaft portion 70 that slides in the axial direction. An annular projecting portion 68 for positioning the spring 37 is formed on the outer peripheral edge of the base portion 46. A groove portion 60 extending in a spiral shape is formed on the outer wall surface of the sliding shaft portion 70. The groove portion 60 corresponds to a spiral passage that communicates the upstream flow path 25a and the downstream flow path 25c via the valve body 36b. In the present embodiment, the groove portion 60 extending spirally is formed on the outer wall surface of the sliding shaft portion 70 of the closing portion 44b. However, the spiral groove portion 60 may be provided on the inner wall surface of the inner passage 58 of the valve body 36b. .

  The sliding shaft portion 48 of the valve body 36b is inserted into the upstream flow hole 38 of the housing 35 so as to be relatively slidable. The T-shaped main body portion 65 of the valve body 36b has a shaft portion 66 side thereof. Arranged in the valve body accommodating chamber 39 so as to be directed toward the closing portion 44b constituting the housing 35, and the sliding shaft portion 70 of the closing portion 44b slides relatively along the inner passage 58 of the valve body 36b. It can be inserted freely. As a result, the valve body 36b is movable in the valve body accommodating chamber 39 in a direction along the upstream flow hole 38 of the housing 35. Further, between the disc-shaped portion 67 of the T-shaped main body portion 65 of the valve body 36b and the base portion 46 of the closing portion 44b of the housing 35, the closed portion 44b around the shaft portion 66 of the T-shaped main body portion 65. The spring 37 is disposed inside the annular projecting portion 68. By the biasing force of the spring 37, the T-shaped main body portion 65 is biased in a direction away from the closing portion 44 b of the housing 35 (direction in contact with the bottom surface of the housing recess 43 of the housing 35). The hole 38 and thus the flow path 25 are closed. However, since the spiral groove portion 60 is formed on the outer wall surface of the sliding shaft portion 70 of the closing portion 44b, the disk-shaped portion 67 of the T-shaped main body portion 65 contacts the bottom surface of the housing recess 43 of the housing 35. Even in the contacted state (the state shown in FIG. 5), the upstream channel 25a and the downstream channel 25c communicate with each other.

  Next, the operation of the shock absorber 1b according to the second embodiment of the present invention will be described. When the piston rod 16 extends and contracts, the hydraulic oil in the rod-side oil chamber 18 opens the valve mechanism 30b in the flow path 25 and flows into the reservoir chamber 6. At this time, like the shock absorber 1a according to the first embodiment, the speed of the piston 15 is in a low speed range, that is, the T-shaped main body portion 65 of the valve body 36b is moved by the biasing force of the spring 37 of the housing recess 43 of the housing 35. In a situation where the state of contact with the bottom surface (the state of FIG. 5) is maintained, specifically, the groove portion 60 is formed in a spiral shape by the spiral groove portion 60 provided in the sliding shaft portion 70 of the closing portion 44b. Since the flow path length through which the hydraulic oil flows is made as long as possible, the damping force characteristic is changed from the orifice characteristic proportional to the square of the piston speed to the flow path characteristic as shown in FIG. And the flow path characteristic can be brought close to a linear characteristic proportional to the piston speed.

Further, when the speed of the piston 15 is increased, the disc-shaped portion 67 of the T-shaped main body portion 65 of the valve body 36 b is separated from the bottom surface of the housing recess 43 of the housing 35 against the biasing force of the spring 37, When the opening 59 (inner passage 58) of the sliding shaft portion 48 of the body 36b begins to communicate with the valve body housing chamber 39, the hydraulic oil moves along with the sliding shaft portion 70 of the closing portion 44b as the valve body 36b moves. As shown in FIG. 6, the damping force characteristic is changed from the flow path characteristic (the proportional constant of the damping force with respect to the piston speed is large) to the valve characteristic (as shown in FIG. 6). When the proportional constant of the damping force with respect to the piston speed is small), the flow path characteristic and the valve characteristic can be connected by a smooth curved line that slightly protrudes upward without changing abruptly as in the prior art.
Thereafter, when the speed of the piston 15 further increases (medium / high speed range), the opening area of the opening 59 (inner passage 58) of the sliding shaft portion 48 with respect to the valve body housing chamber 39 gradually increases, thereby reducing damping force characteristics. As a result, valve characteristics can be obtained.

  In the shock absorber 1b according to the second embodiment described above, in particular, the groove portion 60 extending spirally on the outer wall surface of the sliding shaft portion 70 of the closing portion 44b that slides along the inner passage 58 of the valve body 36b. As a damping force characteristic, the flow path characteristic and the valve characteristic can be connected by a smooth curved line that slightly protrudes upward. As a result, similar to the shock absorber 1a according to the first embodiment, it is possible to suppress abnormal noise (such as vibration sound of the valve body 36b) and a sensation that may occur at the boundary between different damping force characteristics.

1a, 1b shock absorber, 2 outer cylinder, 3 cylinder, 6 reservoir chamber, 15 piston, 16 piston rod, 18 rod side oil chamber, 19 anti-rod side oil chamber, 25 channel, 25a upstream channel, 25c downstream Flow path, 30a, 30b Valve mechanism, 36a, 36b Valve body, 37 Spring (spring means), 39 Valve body storage chamber, 48 Sliding shaft portion, 58 Inner passage, 59 Opening portion, 60 Spiral groove portion (spiral) Passage), 70 Sliding shaft

Claims (4)

A cylinder filled with working fluid inside,
A piston inserted into the cylinder and dividing the cylinder into two chambers;
A piston rod connected to the piston and extending outward from the cylinder;
A flow path in which a working fluid flows by sliding the piston in the cylinder;
A valve mechanism that is provided in the flow path and adjusts the flow of the working fluid that passes through the flow path as the piston moves,
The valve mechanism is
A valve body that is movably accommodated in a valve body housing chamber formed in the flow path, and opens and closes the flow path;
Spring means for biasing the valve body in a direction to close the flow path,
The valve body has a sliding shaft portion that slides in the flow path,
Provided between the outer wall surface of the sliding shaft and the inner wall surface of the flow path is a spiral passage that communicates the upstream side and the downstream side of the flow path via the valve body,
A shock absorber characterized in that the flow path length of the working fluid flowing through the spiral passage changes with the movement of the valve body. The sliding shaft portion has an inner passage extending in the axial direction from the end surface in the inside thereof, and an opening portion opened from the outer wall surface so as to communicate with the inner passage,
2. The shock absorber according to claim 1, wherein the flow path is opened and closed by opening and closing the opening with respect to the valve body housing chamber as the valve body moves. A cylinder filled with working fluid inside,
A piston inserted into the cylinder and dividing the cylinder into two chambers;
A piston rod connected to the piston and extending outward from the cylinder;
A flow path in which a working fluid flows by sliding the piston in the cylinder;
A valve mechanism that is provided in the flow path and adjusts the flow of the working fluid that passes through the flow path as the piston moves,
The valve mechanism is
A valve body that is movably accommodated in a valve body housing chamber formed in the flow path, and opens and closes the flow path;
Spring means for biasing the valve body in a direction to close the flow path,
The valve body has an inner passage extending through the valve body so as to communicate with the upstream side and the downstream side of the flow path,
A sliding shaft that slides in the inner passage is provided in the valve body housing chamber, and the flow path is interposed between the outer wall surface of the sliding shaft portion and the inner wall surface of the inner passage through the valve body. A spiral passage that communicates the upstream side and the downstream side of
A shock absorber characterized in that the flow path length of the working fluid flowing through the spiral passage changes with the movement of the valve body. The valve body has an opening that is open from the outer wall surface thereof to communicate with the inner passage,
4. The shock absorber according to claim 3, wherein the flow path is opened and closed by opening and closing the opening with respect to the valve body housing chamber as the valve body moves.

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