JP2002039248A - Hollow piston rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity when fixing of a plug and processing of an oil hole are applied on a rod body, in a hollow piston rod. SOLUTION: In the hollow piston rod 3, the plug 26 is caulked by a caulking part 27 consisting of cut pieces produced during drilling of an oil hole 25 of a rod body 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hollow piston rod used for a hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, a hydraulic shock absorber using a hollow piston rod has been proposed in order to reduce the weight and the like.
33355). In this hollow piston rod, a rod body inserted into a cylinder of a hydraulic shock absorber is hollow, a piston is integrally provided with the rod body, a hollow portion of the rod body is used as an oil passage, and a side wall of the hollow portion of the rod body. And an oil hole communicating with the oil passage is provided, and a plug is fixed immediately above the oil hole in the hollow portion of the rod body. The plug directly above the oil hole provided in the rod body of the hollow piston rod is an essential configuration for those that use the hollow part of the rod body as the oil passage. The air that has entered the entire area of the hollow part cannot be evacuated, resulting in malfunction of the hydraulic shock absorber.

[0003]

In the prior art, when a fixing groove of a rebound seat is formed in a rod body of a hollow piston rod, a plug in the rod body is swaged and fixed. An oil hole is formed on the side wall immediately below the plug. For this reason, the fixing of the plug to the rod body of the hollow piston rod and the processing of the oil hole are performed in different steps, resulting in poor productivity.

[0004] It is an object of the present invention to improve the productivity of a hollow piston rod when a plug is fixed to a rod body and an oil hole is processed.

[0005]

According to a first aspect of the present invention, a rod body inserted into a cylinder of a hydraulic shock absorber is hollow.
A piston that integrally defines two oil chambers in the cylinder is provided integrally with the rod body, a hollow portion of the rod body is used as an oil passage communicating with the oil chamber, and the oil is provided on a side wall of the hollow portion of the rod body. In a hollow piston rod having an oil hole communicating with a path and a plug fixed directly above the oil hole in the hollow portion of the rod body, a caulking formed by a section when the oil hole of the rod body is drilled The plug is swaged by a part.

According to a second aspect of the present invention, in the first aspect of the present invention, an outer step portion for supporting a rebound rubber is formed on the outer periphery of the rod body. The plug is back-supported on an inner step formed on the periphery, and the plug is sandwiched between the caulking section and the inner step.

According to a third aspect of the present invention, in the first or second aspect, a damping force generating valve device is further provided in a hollow portion of the rod body.

[0008]

According to the first aspect of the present invention, the following operations are provided. In the hollow piston rod, a piece formed when an oil hole is formed in the rod body is used as a caulking portion of the plug. For this reason, the fixing of the plug to the rod body and the processing of the oil hole are simultaneously performed in one process, so that the number of processes can be reduced and the productivity can be improved.

According to the second aspect of the present invention, the following operations are provided. The step formed on the rod body to support the rebound rubber can also be used for back support of the plug,
The plug can be securely fixed with a simple structure. Since a step for supporting the rebound rubber is formed in the rod body, it is not necessary to form a rebound seat fixing groove in the rod body, and this step can be used as a rebound sheet fixing section, and the rebound sheet is not necessarily required. The rebound rubber can be directly supported on the step without using a sheet.

According to the third aspect of the invention, the following effects are obtained. The damping force can be generated by the damping force generating valve device provided in the hollow portion of the rod body.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a main part showing a hydraulic shock absorber, FIG. 2 shows a hollow piston rod, (A) is an overall sectional view, (B) is an enlarged sectional view of a main part, and FIG. FIG. 4 is a cross-sectional view showing a base valve device, FIG. 4 is a schematic diagram showing a manufacturing process of a hollow piston rod, and FIG. 5 is a schematic diagram showing a drilling and caulking device.

As shown in FIG. 1, the hydraulic shock absorber 10 has a double pipe damper structure having an outer tube 11 and a cylinder 12, and a hollow piston rod 13 is inserted into a cylinder 12 built in the outer tube 11, The upper end of the piston rod 13 is connected to the vehicle body side, and the outer tube 11 is connected.
By connecting the lower end of the vehicle to the wheel side, a suspension system for the vehicle is formed. The lower end of the outer tube 11 has a knuckle bracket 14 as a mounting bracket for the wheel side.
Is fixed, and a mounting bracket (not shown) to the vehicle body side is fixed to an upper end portion thereof.

The hydraulic shock absorber 10 is installed around the lower spring seat 15 on the outer periphery of the outer tube 11 and the piston rod 13 and is supported on the rear side of the vehicle-side mounting bracket via a thrust bearing (not shown). A suspension spring 16 is interposed between the upper spring seat (not shown). A tie rod mounting arm 17 is fixed to the outer periphery of the outer tube 11.

The cylinder 12 has a rod guide 18 through which the piston rod 13 passes. The outer tube 11 has an oil seal assembly 19 through which the piston rod 13 passes above the rod guide 18. The assembly 19 is sandwiched between the upper end of the cylinder 12 and the upper crimping portion of the outer tube 11.

As shown in FIGS. 1 and 2, the hollow piston rod 13 has a hollow rod body 21 inserted into the cylinder 12, and the rod body 21 is inserted in the axial direction of the rod body 21 from the insertion end side of the cylinder 12 in order. The piston portion 22A, the large-diameter portion 22B, the medium-diameter portion 22C, and the small-diameter portion 22D are made smaller in this order. The hollow piston rod 13 has a piston 23 formed by banding a resin ring around the outer periphery of the piston portion 22A of the rod body 21.
Is provided integrally.

The hollow piston rod 13 is connected to the rod body 2
A piston valve device (damping force generating valve device) 30 described later is built in the inner periphery of the first piston portion 22A, and the inside of the cylinder 12 is provided with a piston 23 and a piston valve device 30.
The piston-side oil chamber 40A and the rod-side oil chamber 4
0B. The hollow piston rod 13 has an oil passage 24 formed in the hollow portion of the rod main body 21 so as to be able to communicate with the piston side oil chamber 40A via the piston valve device 30, and communicates with the oil passage 24 to form the rod side oil chamber. An oil hole 25 opening to 40 </ b> B is provided on the side wall of the hollow portion of the rod body 21.

The hollow piston rod 13 is connected to the rod body 2
A plug 26 is fixed just above the oil hole 25 in the hollow portion 1. The plug 26 is provided with O
It is sealed to the inner periphery of the rod body 21 with the seal member 26A such as a ring attached. The plug 26 has an oil hole 25
By closing the oil passage 24 immediately above the oil passage 24, the accumulation of air in the oil passage 24 when the hydraulic shock absorber 10 is assembled can be eliminated, and the air in the rod body 21 can be prevented from entering the oil chamber. It serves as a ceiling surface for guiding the air that has entered into the oil hole 24 and is discharged from the oil hole 25 to the side of the rod-side oil chamber 40B, thereby preventing malfunction of the hydraulic shock absorber 10.

The hollow piston rod 13 is connected to the rod body 2
The plug 26 is caulked by the caulking part 27 formed by the section when the one oil hole 25 is formed.

The hollow piston rod 13 is connected to the rod body 2
An outer step portion 28A for supporting a rebound rubber 102, which will be described later, is formed on the outer periphery of the inner step portion 2 formed on the inner periphery of the rod body 21 corresponding to the outer step portion 28A.
8B, the plug 26 is supported on the back surface, and the plug 26 is sandwiched and fixed between the caulked portion 27 and the inner step portion 28B.
The hollow piston rod 13 is connected to the rebound rubber 10
2 can be directly supported on the step portion 28A of the rod body 21 (or via a rebound seat).

The hollow piston rod 13 is
A screw portion 29A for fixing a mount or the like is provided on the small-diameter portion 22D protruding to the outside of the rod body 21. The hollow portion of this portion of the rod body 21 is sealed with a ball 29.

The manufacturing process of the hollow piston rod 13 will be described later. The hydraulic shock absorber 10 includes a piston valve device (extension-side damping force generator) 30 and a base valve device (compression-side damping force generator) 50. The hydraulic shock absorber 10 suppresses the expansion and contraction vibration of the cylinder 12 and the piston rod 13 due to the absorption of the impact force by the suspension spring 16 by the damping force generated by the piston valve device 30 and the base valve device 50.

(Piston Valve Device 30) (FIGS. 1 and 2) As shown in FIG. 2, the piston valve device 30 has a partition wall 31 formed on the inner periphery of a piston portion 22A integrally provided with a piston 23 of a hollow piston rod 13. The check valve 35 on the oil passage 24 side and the disc valve 36 on the opposite oil passage 24 side are fixed by a bolt 33 penetrating the partition wall 31 and a nut 34 fastened to the bolt 33 by being incorporated and fixed by the caulking portion 32. keeping. The piston 23 and the partition 31 of the piston valve device 30 divide the inside of the cylinder 12 into the piston rod 13.
Is divided into a piston-side oil chamber 40A in which the piston rod 13 is stored and a rod-side oil chamber 40B in which the piston rod 13 is stored. The pressure side flow path 41A is a check valve 3
5, the extension side flow path 41B is opened and closed by the disc valve 36.

Accordingly, in the piston valve device 30 of the hydraulic shock absorber 10, the piston side oil chamber 4
The oil of 0A passes through the pressure-side flow path 41A, deforms and opens the check valve 35, and is guided to the rod-side oil chamber 40B. Further, at the time of extension, the oil in the rod-side oil chamber 40B passes through the extension-side flow path 41B and deflects and opens the disk valve 36, is guided to the piston-side oil chamber 40A, and generates an extension-side damping force.

(Base Valve Device 50) (FIGS. 1 and 3) The hydraulic shock absorber 10 comprises an outer tube 11 and a cylinder 12
Is defined as a reservoir chamber 51, and the interior of the reservoir chamber 51 is partitioned into an oil chamber and a gas chamber. The base valve device 50 is configured by closing a lower end bottom portion 52 of the outer tube 11 and attaching a bottom piece 53 to a lower end portion of the cylinder 12, and a flow path provided between the bottom piece 53 and the bottom portion 52. By 54, the reservoir chamber 51 and the piston side oil chamber 40A are connected. A cage-shaped spring receiving member 55 is press-fitted into the bottom piece 53, and a spring 56, a valve seat 57,
The disk valve 58 is interposed, and the disk valve 58 is connected to the bottom piece 5 via a valve seat 57 by a spring 56.
3 is in pressure contact with the protruding valve seat on the outer periphery.

That is, when the hydraulic shock absorber 10 is compressed, the oil corresponding to the volume of the piston rod 13 that enters the cylinder 12 passes through the flow path 57A of the valve seat 57 to deflect and deform the disk valve 58 to open. Oil chamber 40
A is pushed into the reservoir chamber 51 via the flow path 53A and the flow path 54 of the bottom piece 53, and a pressure-side damping force is obtained.

When the hydraulic shock absorber 10 is extended, oil corresponding to the withdrawal volume of the piston rod 13 withdrawing from the cylinder 12 pushes and opens the valve seat 57 and the disc valve 58 against the spring 56, and The oil is supplied to the piston side oil chamber 40A via the flow path 53A of the bottom piece 53.

Therefore, the hydraulic shock absorber 10 performs a damping action as follows. (At the time of compression) When the hydraulic shock absorber 10 is compressed, in the base valve device 50, a compression-side damping force is generated by the oil passing through the disk valve 58 by bending and deforming the disk valve 58.

(At the time of extension) When the hydraulic shock absorber 10 is extended,
In the piston valve device 30, the disc valve 36
The oil passing through the deflecting member generates an extension damping force.

Due to the damping force on the compression side and the extension side, the expansion and contraction vibration of the hydraulic shock absorber 10 is suppressed.

The outer tube 11 is provided with a bump stopper 101. When the outer tube 11 is most compressed, the bump stopper 101 is attached to a compression side bumper (not shown) provided in the piston rod 13.
To control the maximum compression stroke. Further, the piston rod 13 includes a rebound rubber 102 which is locked to the step 28A of the rod body 21. When the piston rod 13 is fully extended, the rebound rubber 102 is attached to the end surface of the rod guide 18 described above.
And the maximum elongation stroke can be regulated.

Hereinafter, the manufacturing process of the hollow piston rod 13 constituting the hydraulic shock absorber 10 will be described (FIGS. 4 and 5). (1) Enlarging the diameter of one end of the hollow material to be the rod body 21 to form a large diameter portion 22B (FIG. 4 (A)), and further forming a piston portion 22A (FIG. 4 (B)). Steps 28A and 28B are formed at the boundary between the portion 22B and the middle diameter portion 22C (FIG. 4).
(B)). At the same time, the other end of the hollow material to be the rod body 21 is drawn to form a small diameter portion 22D (FIG. 4).
(B)).

(2) The rod body 21 is quenched, tempered and straightened.

(3) A plug 26 with a sealing material 26A is inserted into the inner periphery of the large diameter portion 22B of the rod body 21 and pushed into the inner step 28B of the large diameter portion 22B. , An oil hole 25 is formed in the side wall of the rod body 21 immediately below the plug 26, and the plug 26 is formed by a caulking portion 27 formed of a section formed by the formation of the oil hole 25.
Is fixed by caulking (FIG. 4C).

As shown in FIG. 5, the boring and caulking device 60 has the rod body 21 set at the processing center near the support 61 and the piston 22A and the large-diameter portion 2 of the rod body 21.
The above-mentioned plug 26 is pressed and held against the inner step portion 28B of the large diameter portion 22B by the core mold 62 inserted into the 2B. Annular body 6 supported by support body 61 and located around the processing center
3 and a guide rod 64 is erected on the guide rod 64.
A plurality of punches 6 slidably supported on a wedge surface 65A of the elevating body 65 at a plurality of circumferential positions of the annular body 63 in a direction orthogonal to the processing center.
7 against the wedge surface 67A. The abutment corner 63A of the annular body 63 is brought into contact with the outer step portion 28A of the rod body 21, and the rod body 21 is held by the annular body 63 and the core mold 62. When the elevating body 65 is pushed in, the lower semicircular cutting edge 68A of the punch 67 cooperates with the semicircular cutting edge 62A of the punch 67 to shear the side wall of the rod body 21 as shown in the left half of FIG. The resulting section 27A is pushed into the inner diameter side of the rod body 21 by the upper tapered rake face 68B of the punch 67, and is pushed up.
7A is the above-described caulking portion 27 for the plug 26.

(4) An inner surface cutting process for mounting the partition 31 of the piston valve device 30 on the piston portion 22A of the rod body 21, and an outer surface cutting for forming a thin portion serving as a caulking portion 32 for fixing the partition 31. Processing, small diameter part 22
The threaded portion 29A is rolled to D. The ball 29 is pressed into the hollow portion of the small diameter portion 22D of the rod body 21 (FIG. 4).
(D)).

In the hollow piston rod 13,
The oil hole 25 and the caulking portion 27 are preferably provided at a plurality of positions in the circumferential direction of the rod body 21 (for example, the plug 26 can be securely fixed by providing two positions, preferably four positions). Molding. In addition, hollow piston rod 1
In 3, the piston 23 is formed integrally with the piston portion 22A of the rod body 21, so that a ring groove is provided on the outer periphery of the piston portion 22A, and resin is banded around the outer periphery of the ring groove to form the piston 23. The ring grooves are formed by cutting a plurality of ring grooves in the axial direction of the outer surface of the piston portion 22A when the inner surface of the piston portion 22A is cut for the partition wall 31 in the above (4).

According to the present embodiment, the following operations are provided. In the hollow piston rod 13, a piece formed when the oil hole 25 is formed in the rod body 21 is used as the caulking portion 27 of the plug 26. Therefore, in one process, the plug 26 is fixed to the rod body 21 and
Since the oil holes 25 are simultaneously processed, the number of steps can be reduced and productivity can be improved.

The steps 28A and 28B formed on the rod body 21 for supporting the rebound rubber 102 can be used for supporting the back of the plug 26.
Can be securely fixed by a simple structure. Note that a step 2 for supporting the rebound rubber 102 on the rod body 21 is provided.
8A and 28B, there is no need to form a rebound sheet fixing groove in the rod body 21.
A and 28B can be used as the rebound seat fixing portion, and the rebound rubber 102 can be directly supported on the step portions 28A and 28B without necessarily using the rebound seat.

A damping force can be generated by a damping force generating valve device provided in the hollow portion of the rod body 21.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed within the scope of the present invention. The present invention is also included in the present invention.

[0041]

As described above, according to the present invention, in the hollow piston rod, productivity can be improved when the plug is fixed to the rod body and the oil hole is processed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a hydraulic shock absorber.

2A and 2B show a hollow piston rod, wherein FIG. 2A is an overall sectional view, and FIG. 2B is an enlarged sectional view of a main part.

FIG. 3 is a sectional view showing a base valve device.

FIG. 4 is a schematic view showing a manufacturing process of a hollow piston rod.

FIG. 5 is a schematic diagram showing a perforation caulking device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hydraulic shock absorber 12 Cylinder 13 Hollow piston rod 21 Rod main body 23 Piston 24 Oil passage 25 Oil hole 26 Plug 27 Caulking part 28A Outer step part 28B Inner step part 30 Piston valve device (damping force generating valve device)

Claims (3)

[Claims] 1. A rod body inserted into a cylinder of a hydraulic shock absorber is hollow, and a piston that defines two oil chambers in the cylinder is provided integrally with the rod body. An oil passage communicating with the oil chamber, an oil hole communicating with the oil passage is provided on a side wall of the hollow portion of the rod body, and a plug is fixed in the hollow portion of the rod body directly above the oil hole. A hollow piston rod, wherein a plug is caulked by a caulking portion formed by a section when an oil hole of the rod body is formed. 2. An outer step for supporting a rebound rubber is formed on an outer periphery of the rod body, and the plug is formed on an inner step formed on an inner periphery of the rod body corresponding to the outer step. The hollow piston rod according to claim 1, wherein the plug is supported and the plug is sandwiched between the caulked portion and the inner step portion. 3. The hollow piston rod according to claim 1, wherein a damping force generating valve device is provided in a hollow portion of the rod body.