JP5568156B2 - piston - Google Patents

Description

The present invention relates to an improvement of a piston.

This type of piston is, for example, slidably inserted into the cylinder of the shock absorber and divides the inside of the cylinder into two pressure chambers. And a pressure side port through which hydraulic oil passes when the container contracts. In addition, leaf valves are stacked on the top and bottom of the piston, and the outlet ends of the extension side port and the pressure side port are opened and closed by these leaf valves, and pass through the extension side port and the pressure side port when the shock absorber expands and contracts. A resistance is applied to the flow of the hydraulic oil by the leaf valve to cause a difference between the pressures in the two pressure chambers, thereby generating a damping force.

In the piston used as described above, the expansion side port and the compression side port are penetrated from the direction intersecting the axis of the piston, and the inlet end of the expansion side port is located on the outer peripheral side from the outlet end of the compression side port. In addition, the inlet end of the compression side port is arranged on the outer peripheral side from the outlet end of the expansion side port, and annular valve seats are provided at the upper and lower ends of the piston to separate the inlet end and the outlet end of each port. There is something like that.

In such a piston, the valve seat diameters of both the expansion side port and the pressure side port can be set large, so that a large pressure receiving area of the leaf valve can be secured and a damping force can be generated with high responsiveness. Although there is an advantage, the process of penetrating from the direction intersecting the axis of the piston in forming each port is complicated and increases the manufacturing cost.

Therefore, it is assumed that the piston is configured by laminating two disks up and down, and a plurality of long grooves in the radial direction are formed on the same circumference of the stacked surface side end of each disk, and every other long groove, Provided with an outlet hole that communicates the portion from the inner periphery of the long groove and the end opposite to the end of the lamination surface, and the portion from the outer periphery of the remaining long groove and the end opposite to the end of the lamination surface An inlet hole is provided so that the inlet hole is disposed on the outer peripheral side of the outlet hole at the opposite end, and the inlet hole and the outlet hole are provided at the opposite end of the piston. There is a piston that configures each port by connecting an outlet hole in one disk and an inlet hole in the other disk via the long groove, separated by an annular valve seat (see, for example, Patent Documents 1 to 3). .

Pistons composed of these two disks do not require processing to form ports, and each disk can be formed by sintering, using the unevenness provided at the end of the laminated surface facing each other. The pistons can be manufactured by integrating the disks by press fitting.

In addition, there is also a proposal in which the piston is configured by stacking three disks, and even in this proposal, each disk can be sintered and formed without the need for processing to form a port. In this proposal, instead of integrating the disks with each other, the disks are assembled to the piston rod in a stacked state, and then tightened with a piston nut to be fixed to the piston rod. (For example, refer to Patent Document 4).

Japanese Patent Publication No. 48-21378 JP 2005-188602 A Japanese Patent No. 3828584 JP 2007-198515 A

However, in the pistons disclosed in the above-mentioned patent documents 1 to 3, after manufacturing the piston by integrating the disks, it is necessary to mount the piston ring on the outer periphery thereof. The boundary between the upper disk and the lower disk will be placed, and if the processing accuracy is not improved when forming both disks, a step will be formed at the boundary, and the piston attached to the outer periphery There is a possibility that irregularities appear on the outer peripheral surface of the ring due to the influence of the stepped portion.

This piston ring is a member that is in direct sliding contact with the cylinder of the shock absorber, and if the outer peripheral surface of the piston ring is uneven, it gives unnecessary resistance to the expansion and contraction operation of the shock absorber and hinders the smooth expansion and contraction operation of the shock absorber. In order to prevent this, it is necessary to perform post-processing such as cutting the mounting portion to which the piston ring of the piston is mounted, which complicates the processing of the piston.

Further, in the piston disclosed in Patent Document 4, since the piston ring is mounted only on the outer periphery of the disk arranged in the middle, the above-described problem does not occur, but the piston is configured by three disks. In addition, since the number of parts is large and each disk is fixed and not integrated, the assembly work to the piston rod is troublesome and the parts management becomes complicated.

Therefore, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a piston that is easy to assemble and easy to process.

In order to achieve the above object, the problem solving means in the present invention is a piston connected to a piston rod,
An outer piece having a bottom portion provided with an insertion hole through which a plurality of passages and a piston rod are inserted and a cylindrical portion rising from the outer periphery of the bottom portion, and a piston ring mounted on the outer periphery;
An inner piece having a disc shape and having a plurality of passages and an insertion hole through which the piston rod is inserted;
The passage provided in the inner piece includes an inner piece outlet passage and an inner piece inlet passage made of a groove,
The passage provided in the outer piece includes an outer piece outlet passage and an outer piece inlet passage,
By fitting the inner piece to the cylindrical portion and laminating it on the bottom of the outer piece, the inner piece outlet passage and the outer piece inlet passage are communicated with each other, and the inner piece inlet passage and the outer piece outlet passage are communicated with each other.
Further, only set the protrusion inside the shorter radially than the length in the radial direction of the groove length of the tubular portion, the detent inner piece to the outer piece of the convex portion is inserted into said groove And being positioned in the circumferential direction.
Similarly, another problem solving means is a shock absorber provided with the above-described piston.

According to the piston of the present invention, the piston ring is mounted on the outer periphery of the outer piece, and there is no problem that irregularities are formed on the outer peripheral surface of the piston ring. In addition, it is not necessary to machine the mounting part precisely compared to conventional pistons that integrate two discs, making piston processing easier and reducing the number of processing steps when manufacturing pistons. The manufacturing cost can be reduced.

At that time, by inserting the convex portion provided inside the cylindrical portion of the outer piece into the groove, the inner piece is prevented from rotating with respect to the outer piece and positioned in the circumferential direction, and the outer portion provided on the outer piece. The opening of the piece inlet passage and the opening of the inner piece outlet passage provided in the inner piece face each other, and the opening of the outer piece outlet passage provided in the outer piece and the inner piece inlet passage provided in the inner piece face each other. To do.

It is YY 'sectional drawing of the piston in one Embodiment. It is a top view of the piston in one embodiment. It is a bottom view of the piston in one embodiment. It is a top view of the outer piece of the piston in one embodiment. It is a bottom view of the inner piece of the piston in one embodiment.

The valve structure of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the piston 1 in one embodiment is a disc-like shape that is fitted to the bottomed cylindrical outer piece 10 and the cylindrical portion 12 of the outer piece 10 and is stacked on the bottom 11 of the outer piece 10. , And is fixed to the tip of the piston rod 2 of the shock absorber.

The outer piece 10 is formed with an outer piece inlet passage 13 and an outer piece outlet passage 14 as passages, and the inner piece 20 is formed with an inner piece inlet passage 21 and an inner piece outlet passage 22 as passages. The outer piece inlet passage 13 and the inner piece outlet passage 22 are communicated with each other, and the outer piece outlet passage 14 and the inner piece inlet passage 21 are communicated with each other. As a result, the upper and lower portions of the piston 1 in FIG. 1 are communicated with each other through these passages 13, 14, 21, and 22.

In the outer piece 10, the lower end opening end of the outer piece inlet passage 13 is provided on the outer peripheral side from the lower end opening end of the outer piece outlet passage 14, and the lower end opening end of the outer piece inlet passage 13 and the outer piece outlet passage are provided. 14, an annular outer piece valve seat 15 is provided between the lower end opening end of the inner side piece 14. In the inner piece 20, the upper end opening end of the inner piece inlet passage 21 is on the outer peripheral side from the upper end opening end of the inner piece outlet passage 22. An annular inner piece valve seat 23 is provided between the upper end opening end of the inner piece inlet passage 21 and the upper end opening end of the inner piece outlet passage 22.

Further, a leaf valve 3 that is seated on the outer piece valve seat 15 and opens and closes the outer piece outlet passage 14 is stacked on the lower side of the outer piece 10 in FIG. The leaf valve 4 which is seated on the inner piece valve seat 23 and opens and closes the inner piece outlet passage 22 is laminated, and the piston 1 together with the leaf valves 3 and 4 is arranged with the inner piece 20 at the tip 2a of the piston rod 2. 1 is fixed by a piston nut 5 at the top.

On the other hand, a shock absorber to which the piston 1 is applied is well known and will not be described in detail, but specifically, for example, a cylinder 6 and a head member for sealing the upper end of the cylinder 6 (not shown). ), A piston rod 2 slidably penetrating a head member (not shown), the piston 1 provided at the tip 2a of the piston rod 2, and two pressures separated by the piston 1 in the cylinder 6 The upper chamber 7 and the lower chamber 8 which are chambers, a sealing member (not shown) for sealing the lower end of the cylinder 6, and a change in the cylinder volume corresponding to the volume of the piston rod 2 protruding and retracting from the cylinder 6 are not shown. The cylinder 6 is configured to include a reservoir or an air chamber, and the cylinder 6 is filled with a fluid, specifically, for example, hydraulic oil.

Therefore, in the case of this shock absorber, when the piston 1 moves upward in FIG. 1 with respect to the cylinder 6, the pressure in the upper chamber 7 rises and the leaf sits on the outer piece valve seat 15 provided in the outer piece 10. Since the valve 3 is deflected downward in FIG. 1 and the outer piece outlet passage 14 is opened, the hydraulic oil passes through the inner piece inlet passage 21 of the inner piece 20 and the outer piece outlet passage 14 of the outer piece 10 and passes through the upper chamber. 7 to move to the lower chamber 8, the leaf valve 3 gives resistance to the flow of the hydraulic oil to cause a predetermined pressure loss, and a predetermined extension side damping force is generated in the shock absorber. . That is, the inner piece inlet passage 21 and the outer piece outlet passage 14 function as an extension port through which hydraulic oil passes when the shock absorber extends, and the leaf valve 3 functions as an extension-side damping valve.

On the contrary, when the piston 1 moves downward in FIG. 1 with respect to the cylinder 6, the pressure in the lower chamber 8 rises and the leaf valve 4 seated on the inner piece valve seat 23 of the inner piece 20 is moved upward in FIG. 1. And the inner piece outlet passage 22 is opened, so that the hydraulic oil moves from the lower chamber 8 to the upper chamber 7 through the outer piece inlet passage 13 of the outer piece 10 and the inner piece outlet passage 22 of the inner piece 20. Accordingly, the leaf valve 4 gives resistance to the flow of the hydraulic oil to cause a predetermined pressure loss, and a predetermined extension side damping force is generated in the shock absorber. That is, the outer piece inlet passage 13 and the inner piece outlet passage 22 function as a pressure side port through which hydraulic oil passes when the shock absorber contracts, and the leaf valve 4 functions as a pressure side damping valve.

Hereinafter, each part of the above-described piston 1 will be described in detail. The outer piece 10 is manufactured by sintering molding and has a bottomed cylindrical shape as shown in FIGS. 1 to 4. And a cylindrical portion 12 rising from the outer periphery of the bottom portion 11. In addition, an insertion hole 18 through which the tip 2 a of the piston rod 2 is inserted is provided at the center of the bottom portion 11, and a tapered portion 19 is provided on the outer periphery of the lower end in FIG. Six piece inlet passages 13 and six outer piece outlet passages 14 are provided.

The outer piece entrance passage 13 communicates from the upper end in FIG. 1, which is the opposite end facing the inner piece 20 of the bottom 11, to the lower end in FIG. 1, which is the opposite end of the bottom 11, and is an arch provided at the opposite end The opening 13a has a shape and a vertical hole 13b that opens from the tapered portion 19 provided on the outer periphery of the opposite end of the bottom 11 and communicates with the outer periphery of the opening 13a. The opening 13a is formed at the opposite end. The vertical holes 13b are also arranged on the bottom 11 at equal intervals on the same circumference. Even in the outer piece outlet passage 14, the opposite end portion of the bottom portion 11 leads from the opposite end portion to an arch-shaped opening 14 a provided at the opposite end portion, and the opposite end portion of the bottom portion 11. A vertical hole 14b that opens from the inner circumference side to the circumference where the vertical hole 13b is provided and communicates with the inner circumference side of the opening portion 14a, and an annular window that is provided at the opposite end of the bottom portion 11 and communicates with each vertical hole 14b. 14c, the openings 14a are arranged at equal intervals on the same circumference at the opposite ends, and the vertical holes 14b are arranged on the same circumference at equal intervals in the bottom portion 11. Furthermore, at the opposite end of the bottom portion 11, the openings 13 a and the openings 14 a are alternately arranged in the circumferential direction at equal intervals on the same circumference.

Moreover, it is an inner peripheral side from the circumference where the vertical hole 13b of the outer piece inlet passage 13 is provided at the opposite end portion of the bottom portion 11 and outside the circumference where the vertical hole 14b of the outer piece outlet passage 14 is provided. Specifically, an annular outer piece valve seat 15 is provided on the outer periphery of the annular window 14 c, and the outer piece inlet passage 13 and the outer piece outlet passage 14 are separated by the outer piece valve seat 15.

Further, a convex portion 12a that protrudes toward the inner peripheral side is provided at one location on the inner periphery of the cylindrical portion 12, and six arc-shaped protrusions 12b are arranged at equal intervals on the inner periphery at the upper end in FIG. Is provided.

Further, on the outer periphery of the outer piece 10, there are provided mounting portions 16 made up of a plurality of annular grooves formed side by side in the vertical direction in FIG. Is installed.

As described above, since it is not necessary to provide the outer piece 10 with a hole that intersects the axis in the vertical direction in FIG. 1, the outer piece 10 can be easily manufactured by sintering. is there.

Next, the inner piece 20 will be described. The inner piece 20 is disk-shaped and manufactured by sintering, and as shown in FIGS. 1 to 3 and 5, an insertion hole 24 through which the tip 2 a of the piston rod 2 is inserted is provided at the center. In addition, the outer diameter is set to a diameter that can be fitted to the inner periphery of the cylindrical portion 12 of the outer piece 10, and the wall thickness is larger than the axial length of the cylindrical portion 12, but becomes the outer periphery at the upper end in FIG. When the taper portion 25 is provided on the outer periphery of the counter-facing end portion, and the inner piece 20 is fitted to the tube portion 12 of the outer piece 10 and is closely attached to the bottom portion 11, the outer edge of the taper portion 25 becomes the same height as the inner edge of the tube portion 12. Is set to

The inner piece 20 includes six inner piece inlet passages 21 and six inner piece outlet passages 22 respectively. The inner piece inlet passage 21 is formed by a groove provided from the opposite end portion, which is the lower end in FIG. 1, facing the outer piece 10 in the inner piece 20 to the outer periphery of the opposite portion. The wedge-shaped groove 21a having an arch shape when viewed from the opposite end side and the outer periphery of the inner piece 20 are provided along the axial direction and lead to the wedge-shaped groove 21a. The wedge-shaped groove 21a is arranged at equal intervals on the same circumference at the opposite end, and the vertical groove 21b is also arranged on the inner piece 20 on the same circumference. It is arranged at equal intervals.

The inner piece outlet passage 22 communicates from the opposite end of the inner piece 20 to the opposite end, and is an arch-shaped opening 22a provided at the opposite end, and the opposite end of the inner piece 20, which A vertical hole 22b that opens from the inner circumference side to the circumference where the groove 21b is provided and communicates with the inner circumference side of the opening 22a, and an annular window 22c that is provided at the opposite end of the inner piece 20 and communicates with each vertical hole 22b. The openings 22a are arranged at equal intervals on the same circumference at the opposite end, and the vertical holes 22b are also arranged on the inner piece 20 at equal intervals on the same circumference. Further, at the opposite end of the inner piece 20, the wedge-shaped grooves 21a and the openings 22a are alternately arranged in the circumferential direction at equal intervals on the same circumference.

Moreover, it is an inner peripheral side from the circumference where the vertical hole 21b of the inner piece inlet passage 21 is provided at the opposite end portion of the inner piece 20, and from the circumference where the vertical hole 22b of the inner piece outlet passage 22 is provided. An annular inner piece valve seat 23 is provided outside, specifically, on the outer periphery of the annular window 22 c, and the inner piece inlet passage 21 and the inner piece outlet passage 22 are separated by the inner piece valve seat 23.

In order to integrate the outer piece 10 and the inner piece 20 configured as described above, the inner piece 20 is fitted into the cylindrical portion 12 of the outer piece 10 and the inner piece 20 is laminated on the bottom 11 of the outer piece 10. Let

At that time, as shown in FIG. 1, a convex portion 12a having a radial length shorter than the radial length of the groove is provided inside the cylindrical portion 12 of the outer piece 10, and the convex portion 12a is placed in the groove. Inserting.
That is, by allowing the convex portion 12a to enter any one of the longitudinal grooves 21b provided on the outer periphery of the inner piece 20, the inner piece 20 is prevented from rotating with respect to the outer piece 10 and positioned in the circumferential direction. The opening 13a of the outer piece inlet passage 13 provided in the outer piece 10 and the opening 22a of the inner piece outlet passage 22 provided in the inner piece 20 face each other, and the outer piece outlet passage 14 provided in the outer piece 10 The opening 14a and the wedge-shaped groove 21a of the inner piece inlet passage 21 provided in the inner piece 20 are opposed to each other. Even if the convex part 12a penetrate | invades in the vertical groove 21b, this is not obstruct | occluded.

In addition, the openings 13a and 14a in the outer piece 10 are alternately arranged at the opposing end, and the same number of wedge-shaped grooves 21a and openings 22a in the inner piece 20 are provided as the openings 13a and 14a. Therefore, the inner piece 20 can be positioned with respect to the outer piece 10 by inserting the convex portion 12a into one arbitrarily selected vertical groove 21b, and the openings 13a, 14a, Since the pair 22a and the wedge-shaped groove 21a face each other as a pair, when assembling the inner piece 20 to the outer piece 10, it is possible to save the trouble of checking the positions of the openings 13a, 14a, 22a and the wedge-shaped groove 21a.

As described above, the convex portion 12a is provided for alignment. In this case, the same number of openings 13a, 14a, wedge-shaped grooves 21a, and openings 22a are provided and are alternately arranged. Therefore, it is only necessary to provide one, but when the openings 13a and 14a and the wedge-shaped grooves 21a and the openings 22a are not provided in the same number, a plurality of convex portions 12a are provided. By doing so, alignment can be performed automatically.

Further, it is only necessary that the openings 12a, 14a, 22a and the wedge-shaped groove 21a can be opposed to each other as described above by allowing the convex part 12a to enter the vertical groove 21b. However, the openings 13a, 14a, 22a and the wedge-shaped groove 21a can be exactly opposed to each other by fitting the convex part 12a to the vertical groove 22b without any play.

In this case, the shape of the opening 13a, 14a at the opposite end of the outer piece 10 and the shape of the opening 22a and the inner end 20 of the wedge-shaped groove 21a coincide with each other. The openings 13a, 14a, 22a and the wedge-shaped groove 21a are not limited to the shape and size described above, as long as they do not communicate with each other except for the opposing counterparts.

When the inner piece 20 is incorporated into the outer piece 10 as described above, the outer piece inlet passage 13 and the inner piece outlet passage 22 communicate with each other to form a compression side port, and the outer piece outlet passage 14 and the inner piece 20 are in communication with each other. The piece inlet passage 21 is communicated with each other to form an extension port. Thus, in this piston 1, it is possible to form the expansion side port and the pressure side port without the need for drilling to penetrate the expansion side port and the pressure side port from the direction intersecting the axis of the piston. It can be done.

In the case of this embodiment, after the inner piece 20 is fitted to the cylindrical portion 12 of the outer piece 10, the arc-shaped protrusion 12b provided on the inner side of the cylindrical portion 12 of the outer piece 10 is shown in FIG. Then, the inner piece 20 is tilted inward as shown in FIG. 2, and the inner piece 20 is held by the protrusion 12 b, and the inner piece 20 is firmly fixed to the outer piece 10.

The protrusion 12b is disposed between the vertical groove 22b of the inner piece 20 by positioning with the convex part 12a of the cylindrical part 12 and the vertical groove 22b of the inner piece 20, and the taper portion 25 of the inner piece 20 by the above caulking. Grip.

This caulking process may actually be performed when performing a sizing process in which cold pressing is performed after the outer piece 10 and the inner piece 20 formed by sintering are combined. This is a process that is performed to correct, and is basically performed on a product manufactured by sintering, and it is not necessary to perform only the caulking process of the protrusion 12b alone. There is no cost increase when fixing with.

In this case, the inner piece 20 is provided with a tapered portion 25 and the projection 12b grips the tapered portion 25. However, the tapered portion 25 may not be provided, and in any case, the projection 12b. As long as the outer edge of the inner piece 20 can be gripped.

Further, since the inner piece 20 is held by the protrusion 12b as described above, there is a case where the inner piece 20 is loosely fitted to the cylindrical portion 12 of the outer piece 10 due to a dimensional error between the outer piece 10 and the inner piece 20. However, the inner piece 20 can be securely fixed to the outer piece 10. Therefore, the dimension of the inner piece 20 can be set so that the inner piece 20 can be reliably fitted to the inner periphery of the cylindrical portion 12 of the outer piece 10, and the inner piece 20 can be fitted to the outer piece 10. Does not lead to the situation of becoming impossible.

Further, by crimping the protrusion 12b, the inner piece 20 can be pressed to the bottom 11 side of the outer piece 10 with the protrusion 12b, so that the inner piece 20 can be brought into close contact with the bottom 11 of the outer piece 10 and There is no possibility that the openings 13a, 14a, 22a and the wedge-shaped groove 21a communicate with each other other than the opposing counterpart through the piece 10 and the inner piece 20.

In addition, when the inner piece 20 can be fixed to the outer piece 10 by fitting the inner piece 20 to the cylindrical portion 12 of the outer piece 10, the protrusion 12b is not necessary, but the protrusion 12b is provided. Thus, the various advantages described above can be enjoyed.

Since the piston 1 configured in this way has the piston ring 17 attached to the outer periphery of the outer piece 10 as described above, and there is no problem that the outer peripheral surface of the piston ring 17 is uneven, There is no risk of giving resistance to expansion and contraction, and it is not necessary to precisely process the mounting part as compared to the conventional piston that integrates two disks, making it easier to process the piston 1. The number of processing steps in manufacturing the piston 1 can be reduced, and the manufacturing cost can also be reduced.

Further, in this piston 1, the outer piece 10 and the inner piece 20 are integrated and fixed, and therefore, when assembled to the piston rod 2, the outer piece 10 and the inner piece 20 constituting the piston. Therefore, it is not necessary to manage these separately, so that the assembly work to the piston rod 2 is facilitated, and the parts management is also simplified. Therefore, according to this piston 1, the workability of assembling to the piston rod 2 is good, and the processing becomes easy.

Further, when the inner piece 20 is fitted to the cylindrical portion 12 of the outer piece 10 but is not press-fitted, and the inner piece 10 is fixed to the outer piece 20 with the protrusion 12b, the inner piece 20 is strongly pressed against the outer piece 10. Since the attaching process is not required, the distal ends of the valve seats 15 and 23, which are the valve seat portions with which the leaf valves 3 and 4 abut, and the inner peripheral portion inside the annular windows 14c and 22c may be damaged and deformed. In addition, the generated damping force of the shock absorber does not vary among products, and the shock absorber can exhibit a uniform and stable damping force as intended.

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

The piston of the present invention can be used for a shock absorber.

DESCRIPTION OF SYMBOLS 1 Piston 2 Piston rod 2a Piston rod tip 3, 4 Leaf valve 5 Piston nut 6 Cylinder 7 Upper chamber 8 Lower chamber 10 Outer piece 11 Bottom portion 12 Tube portion 12a Protruding portion 12b Protrusion 13 Outer piece inlet passages 13a, 14a, 22a Opening Portions 13b, 14b, 22b Vertical hole 14 Outer piece outlet passage 14c, 22c Annular window 15 Outer piece valve seat 16 Mounting portion 17 Piston rings 18, 24 Insertion holes 19, 25 Taper portion 20 Inner piece 21 Inner piece inlet passage 21a Wedge-shaped groove 21b Longitudinal groove 22 Inner piece outlet passage 23 Inner piece valve seat

Claims (4)

A piston connected to the piston rod,
An outer piece having a bottom portion provided with an insertion hole through which a plurality of passages and a piston rod are inserted and a cylindrical portion rising from the outer periphery of the bottom portion, and a piston ring mounted on the outer periphery;
An inner piece having a disc shape and having a plurality of passages and an insertion hole through which the piston rod is inserted;
The passage provided in the inner piece includes an inner piece outlet passage and an inner piece inlet passage made of a groove,
The passage provided in the outer piece includes an outer piece outlet passage and an outer piece inlet passage,
By fitting the inner piece to the cylindrical portion and laminating it on the bottom of the outer piece, the inner piece outlet passage and the outer piece inlet passage are communicated with each other, and the inner piece inlet passage and the outer piece outlet passage are communicated with each other.
Further, only set the protrusion inside the shorter radially than the length in the radial direction of the groove length of the tubular portion, the detent inner piece to the outer piece of the convex portion is inserted into said groove piston, characterized in that is positioned in the circumferential direction together to. Providing a protrusion on the inner side of the end of the cylindrical part, caulking the protrusion inward to hold the inner piece with the protrusion, and fitting the convex part into the groove to fix the inner piece to the outer piece The piston according to claim 1. The inner piece outlet passage is provided on an inner peripheral side from an annular inner piece valve seat provided at a counter-facing end opposite to the opposite end facing the outer piece, and the inner piece inlet passage is provided on the inner piece valve. The outer piece outlet passage is formed at the outer periphery from the seat and extending from the opposite end to the outer periphery of the opposite end, and the outer piece outlet passage is the bottom and the opposite end opposite to the opposite end facing the inner piece. The outer piece inlet passage is provided at the outer periphery from the outer piece valve seat, and the convex portion is provided at the inner periphery of the cylindrical portion. The piston according to claim 1, wherein the piston is provided at one location .   A piston according to claim 1, a piston according to claim 2 that cites claim 1, a piston according to claim 3 that cites claim 1, or a claim that cites claim 2. A shock absorber provided with the piston described in 3.

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