JP4441775B2 - Hollow piston rod - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hollow piston rod used in a hydraulic shock absorber.
[0002]
[Prior art]
Conventionally, a hydraulic shock absorber using a hollow piston rod has been proposed in order to reduce the weight (practical 2533355). This hollow piston rod has a hollow rod main body inserted into a cylinder of a hydraulic shock absorber, a piston is integrally provided in the rod main body, a hollow portion of the rod main body serves as an oil passage, and a side wall of the hollow portion of the rod main body Are provided with an oil hole communicating with the oil passage, 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 in the rod body of the hollow piston rod is an essential component for the oil passage in the rod body. If there is no plug, the rod body will be attached to the hydraulic shock absorber. The air that has entered the entire area of the hollow portion cannot be removed, resulting in malfunction of the hydraulic shock absorber.
[0003]
[Problems to be solved by the invention]
In the prior art, when forming the fixing groove of the rebound sheet on the rod body of the hollow piston rod, the plug in the rod body is fixed by caulking, and then the oil hole is directly below the plug on the side wall of the hollow portion of the rod body. Is processed. 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 processes, and the productivity is poor.
[0004]
An object of the present invention is to improve productivity when a plug is fixed to a rod body and an oil hole is processed in a hollow piston rod.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, the rod body inserted into the cylinder of the hydraulic shock absorber is hollow, and a piston that defines two oil chambers in the cylinder is provided integrally with the rod body. A hollow piston in which an oil passage communicating with the oil chamber is provided, an oil hole communicating with the oil passage is provided in a side wall of the hollow portion of the rod body, and a plug is fixed immediately above the oil hole in the hollow portion of the rod body In the rod, an outer step for supporting the rebound rubber is formed on the outer periphery of the rod body, and the plug is supported on the inner step formed on the inner periphery of the rod body corresponding to the outer step. The plug is sandwiched between the caulking portion formed by a section pushed into the inner diameter side of the rod body when the oil hole of the rod body is drilled and the inner stepped portion. is there.
[0006]
According to a second aspect of the present invention, in the first aspect of the present invention, a damping force generating valve device is further provided in the hollow portion of the rod body.
[0008]
[Action]
According to the first aspect of the invention, the following actions (a) and (b) are obtained.
(a) In a hollow piston rod, a section generated when an oil hole is drilled in a rod body is used as a caulking portion of a plug. For this reason, in one process, the plug is fixed to the rod body and the oil hole is processed at the same time, thereby reducing the number of processes and improving the productivity.
[0009]
(b) The step formed on the rod body to support the rebound rubber can also be used to support the back surface of the plug, and the plug can be securely fixed with a simple structure. In addition, since the step part for supporting the rebound rubber was formed in the rod body, it is not necessary to form a rebound sheet fixing groove in the rod body, and this step part can be used as a rebound sheet fixing part, and is not necessarily rebounded. It is also possible to directly support the rebound rubber on the step portion without using a sheet.
[0010]
The invention according to claim 2 has the following action (c) .
(c) A damping force can be generated by a damping force generating valve device provided in the hollow portion of the rod body.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1 is a cross-sectional view of a main part showing a hydraulic shock absorber, FIG. 2 is a cross-sectional view of a hollow piston rod, (A) is an overall cross-sectional view, (B) is an enlarged cross-sectional view of the main part, and FIG. FIG. 4 is a schematic view showing a manufacturing process of a hollow piston rod, and FIG. 5 is a schematic view showing a perforation caulking device.
[0012]
As shown in FIG. 1, the hydraulic shock absorber 10 has a double-tube 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. Is connected to the vehicle body side, and the lower end portion of the outer tube 11 is connected to the wheel side to constitute a vehicle suspension device. A knuckle bracket 14 that is a mounting bracket to the wheel side is fixed to the lower end portion of the outer tube 11, and a mounting bracket (not shown) to the vehicle body side is fixed to the upper end portion.
[0013]
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 back by a vehicle body 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.
[0014]
The cylinder 12 includes a rod guide 18 through which the piston rod 13 passes, and the outer tube 11 includes an oil seal assembly 19 through which the piston rod 13 passes above the rod guide 18, and the rod guide 18 and the oil seal assembly 19. Is held between the upper end portion of the cylinder 12 and the upper end crimped portion of the outer tube 11.
[0015]
Here, 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 piston portion 22 </ b> A in order from the insertion end side to the cylinder 12 in the axial direction of the rod body 21. The large-diameter portion 22B, the medium-diameter portion 22C, and the small-diameter portion 22D are made smaller in that order. The hollow piston rod 13 is integrally provided with a piston 23 formed by banding a resin ring on the outer periphery of the piston portion 22A of the rod body 21.
[0016]
The hollow piston rod 13 incorporates a piston valve device (damping force generating valve device) 30 to be described later on the inner periphery of the piston portion 22A of the rod body 21, and the inside of the cylinder 12 is to be described later by a piston 23 and a piston valve device 30. The oil is divided into a side oil chamber 40A and a rod side oil chamber 40B. The hollow piston rod 13 forms an oil passage 24 that can communicate with the piston-side oil chamber 40 </ b> A via the piston valve device 30 in the hollow portion of the rod body 21, and communicates with the oil passage 24 to communicate with the rod-side oil chamber. An oil hole 25 opening in 40B is provided in the side wall of the hollow portion of the rod body 21.
[0017]
The hollow piston rod 13 has a plug 26 fixed immediately above the oil hole 25 in the hollow portion of the rod body 21. The plug 26 is sealed to the inner periphery of the rod body 21 with a sealing material 26 </ b> A such as an O-ring attached to the upper end side outer peripheral portion or outer peripheral upper surface portion. The plug 26 closes the oil passage 24 immediately above the oil hole 25, thereby eliminating an air pool in the oil passage 24 when the hydraulic shock absorber 10 is assembled, so that the air in the rod body 21 enters the oil chamber. In addition, it becomes a ceiling surface that guides the air that has entered the oil passage 24 and is discharged from the oil hole 25 toward the rod-side oil chamber 40B, thereby preventing the hydraulic shock absorber 10 from malfunctioning.
[0018]
The hollow piston rod 13 is caulked with a plug 26 by a caulking portion 27 formed by a section when the oil hole 25 of the rod body 21 is formed.
[0019]
The hollow piston rod 13 is formed with an outer step portion 28A for supporting a rebound rubber 102, which will be described later, on the outer periphery of the rod body 21, and an inner portion formed on the inner periphery of the rod body 21 corresponding to the outer step portion 28A. The plug 26 is supported on the back surface of the step portion 28B, and the plug 26 is sandwiched and fixed between the crimping portion 27 and the inner step portion 28B. The hollow piston rod 13 can support the rebound rubber 102 directly on the stepped portion 28A of the rod body 21 (or via a rebound sheet).
[0020]
The hollow piston rod 13 is provided with a screw portion 29 </ b> A for fixing a mount or the like to a small diameter portion 22 </ b> D protruding outside the cylinder 12, and the hollow portion of this portion of the rod body 21 is sealed with a ball 29.
[0021]
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 generation device) 30 and a base valve device (compression-side damping force generation device) 50. The hydraulic shock absorber 10 suppresses 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.
[0022]
(Piston valve device 30) (FIGS. 1 and 2)
As shown in FIG. 2, the piston valve device 30 has a partition wall 31 built in the inner periphery of a piston portion 22 </ b> A integrally provided with a piston 23 of a hollow piston rod 13, fixed by a caulking portion 32, and penetrates the partition wall 31. A check valve 35 on the oil passage 24 side and a disk valve 36 on the anti-oil passage 24 side are fixedly held by a bolt 33 and a nut 34 fastened thereto. The piston 23 and the partition wall 31 of the piston valve device 30 partition the inside of the cylinder 12 into a piston-side oil chamber 40A in which the piston rod 13 is not accommodated and a rod-side oil chamber 40B in which the piston rod 13 is accommodated. A pressure side channel 41A and an extension side channel 41B communicating with 40A and 40B are provided. The pressure side channel 41A is opened and closed by the check valve 35, and the extension side channel 41B is opened and closed by the disc valve 36.
[0023]
As a result, in the piston valve device 30 of the hydraulic shock absorber 10, during compression, the oil in the piston-side oil chamber 40A passes through the pressure-side flow path 41A and bends and opens the check valve 35, and opens to the rod-side oil chamber 40B. Led. Further, at the time of extension, the oil in the rod side oil chamber 40B passes through the extension side flow passage 41B to bend and open the disk valve 36 and is guided to the piston side oil chamber 40A to generate an extension side damping force.
[0024]
(Base valve device 50) (FIGS. 1 and 3)
In the hydraulic shock absorber 10, a gap between the outer tube 11 and the cylinder 12 is defined as a reservoir chamber 51, and the interior of the reservoir chamber 51 is divided into an oil chamber and a gas chamber. The base valve device 50 is configured by closing the lower end bottom portion 52 of the outer tube 11 and attaching a bottom piece 53 to the lower end portion of the cylinder 12, and a flow path provided between the bottom piece 53 and the bottom portion 52. 54 connects the reservoir chamber 51 and the piston-side oil chamber 40A. A cage-shaped spring receiving member 55 is press-fitted into the bottom piece 53, and a spring 56, a valve seat 57 and a disc valve 58 are interposed between the bottom piece 53 and the spring receiving member 55. The disc valve 58 is pressed against the protruding valve seat on the outer periphery of the bottom piece 53 through 57.
[0025]
That is, when the hydraulic shock absorber 10 is compressed, the oil corresponding to the volume of the piston rod 13 entering the cylinder 12 passes through the flow path 57A of the valve seat 57 to bend and deform the disk valve 58 to open, and the piston side oil chamber 40A. To the reservoir chamber 51 through the flow path 53A and the flow path 54 of the bottom piece 53 to obtain a compression-side damping force.
[0026]
Further, when the hydraulic shock absorber 10 is extended, the oil corresponding to the retraction volume of the piston rod 13 retreating from the cylinder 12 pushes and opens the valve seat 57 and the disk valve 58 against the spring 56, and the bottom piece 53 from the reservoir chamber 51. The piston-side oil chamber 40A is replenished via the flow path 53A.
[0027]
Therefore, the hydraulic shock absorber 10 performs a damping action as follows.
(When compressed)
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 being flexibly deformed.
[0028]
(When stretched)
When the hydraulic shock absorber 10 is extended, an expansion-side damping force is generated in the piston valve device 30 by the oil passing through the disk valve 36 by being flexibly deformed.
[0029]
The expansion and contraction vibration of the hydraulic shock absorber 10 is suppressed by the damping force on the compression side and the extension side.
[0030]
The outer tube 11 is provided with a bump stopper 101, and at the time of maximum compression, the bump stopper 101 is abutted against a compression side bumper (not shown) provided in the piston rod 13 to restrict the maximum compression stroke. The piston rod 13 includes a rebound rubber 102 locked to the step portion 28A of the rod main body 21. When the piston rod 13 is fully extended, the rebound rubber 102 is abutted against the end surface of the rod guide 18 to restrict the maximum extension stroke. It is possible.
[0031]
Hereinafter, the manufacturing process of the hollow piston rod 13 which comprises the hydraulic shock absorber 10 is demonstrated (FIG. 4, FIG. 5).
(1) Enlarging the diameter of one end of the hollow material to be the rod body 21 to form the large diameter portion 22B (FIG. 4A), and further forming the piston portion 22A (FIG. 4B), the large diameter Step portions 28A and 28B are formed at the boundary between the portion 22B and the medium diameter portion 22C (FIG. 4B). At the same time, the other end portion of the hollow material to be the rod body 21 is drawn to form a small diameter portion 22D (FIG. 4B).
[0032]
(2) The rod body 21 is quenched, tempered and further bent.
[0033]
(3) The plug 26 fitted with the sealing material 26A is inserted into the inner periphery of the large-diameter portion 22B of the rod body 21, and this is pushed into the inner step portion 28B of the large-diameter portion 22B. An oil hole 25 is drilled in the side wall of the rod main body 21 immediately below the plug body 26, and the plug 26 is crimped and fixed by a crimping portion 27 formed of a section generated by the drilling of the oil hole 25 (FIG. 4C).
[0034]
As shown in FIG. 5, the perforating and crimping device 60 sets the rod main body 21 at the processing center on the side of the support body 61, and is inserted into the piston portion 22 </ b> A and the large diameter portion 22 </ b> B of the rod main body 21. 62 holds the above-mentioned plug 26 against the inner step portion 28B of the large diameter portion 22B. A guide rod 64 is erected on an annular body 63 that is supported by the support body 61 and is positioned around the processing center, and an elevating body 65 is mounted on the guide rod 64 so that the elevating body 65 can be raised and lowered. Abutting with wedge surfaces 67A of a plurality of punches 67 slidably supported in a direction orthogonal to the processing center at a plurality of circumferential positions of the body 63. From the state of the right half of FIG. 5 in which the abutting corner portion 63A of the annular body 63 is applied to 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 arc cutting edge 68A of the punch 67 shears the side wall of the rod body 21 in cooperation with the semicircular cutting edge 62A of the punch 67 as shown in the left half of FIG. The section 27A generated thereby is pushed into the inner diameter side of the rod body 21 by the upper tapered rake face 68B of the punch 67, and the section 27A is used as the above-described caulking portion 27 for the plug 26.
[0035]
(4) An inner surface cutting process for loading the partition wall 31 of the piston valve device 30 on the piston portion 22A of the rod body 21 and an outer surface cutting process for forming a thin portion serving as a crimping portion 32 for fixing the partition wall 31 are performed. The threaded portion 29A is rolled into the small diameter portion 22D. The ball 29 is press-fitted into the hollow portion of the small diameter portion 22D of the rod body 21 (FIG. 4D).
[0036]
In the hollow piston rod 13, the oil hole 25 and the caulking portion 27 are arranged at a plurality of positions in the circumferential direction of the rod body 21 (for example, the plug 26 can be reliably fixed by providing two positions, preferably four positions). These are preferably formed simultaneously at a plurality of locations.
Further, in the hollow piston rod 13, in order to provide the piston 23 integrally with the piston portion 22 </ b> A of the rod body 21, a ring groove is provided on the outer periphery of the piston portion 22 </ b> A, and resin is banded on the outer periphery of the ring groove. 23 is formed. The ring groove is provided by cutting a plurality of ring grooves in the axial direction of the outer surface of the piston portion 22A when the inner surface machining for the partition wall 31 is performed on the piston portion 22A in (4).
[0037]
According to this embodiment, there are the following operations.
(1) In the hollow piston rod 13, a section generated when the oil hole 25 is formed in the rod main body 21 is used as the crimping portion 27 of the plug 26. For this reason, the plug 26 is fixed to the rod main body 21 and the oil hole 25 is simultaneously processed in one process, and the number of processes can be reduced and productivity can be improved.
[0038]
(2) The step portions 28A and 28B formed on the rod body 21 for supporting the rebound rubber 102 can be used for supporting the back surface of the plug 26, and the plug 26 can be reliably fixed with a simple structure. Since the step portions 28A and 28B for supporting the rebound rubber 102 are formed on the rod body 21, there is no need to form a rebound sheet fixing groove on the rod body 21, and the step portions 28A and 28B are used as the rebound sheet fixing portion. In addition, the rebound rubber 102 can be directly supported on the stepped portions 28A and 28B without necessarily using a rebound sheet.
[0039]
(3) A damping force can be generated by a damping force generating valve device provided in the hollow portion of the rod body 21.
[0040]
Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Is included in the present invention.
[0041]
【The invention's effect】
As described above, according to the present invention, in the hollow piston rod, when the plug is fixed to the rod body and the oil hole is processed, the productivity can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part showing a hydraulic shock absorber.
FIG. 2 shows a hollow piston rod, (A) is an overall cross-sectional view, and (B) is an enlarged cross-sectional view of a main part.
FIG. 3 is a cross-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 view showing a perforating and caulking device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Hydraulic buffer 12 Cylinder 13 Hollow piston rod 21 Rod main body 23 Piston 24 Oil passage 25 Oil hole 26 Plug 27 Clamping part 28A Outer step part 28B Inner step part 30 Piston valve apparatus (damping force generation valve apparatus)

Claims (2)

The rod body inserted into the cylinder of the hydraulic shock absorber is hollow, a piston that defines two oil chambers in the cylinder is provided integrally with the rod body, and the hollow portion of the rod body communicates with the oil chamber. In the hollow piston rod in which an oil passage is provided, an oil hole communicating with the oil passage is provided in a side wall of the hollow portion of the rod body, and a plug is fixed immediately above the oil hole in the hollow portion of the rod body.
Forming an outer step for supporting the rebound rubber on the outer periphery of the rod body, and supporting the plug on the inner step formed on the inner periphery of the rod body corresponding to the outer step,
A hollow characterized in that the plug is sandwiched between a caulking portion formed by a section pushed into the inner diameter side of the rod main body when the oil hole of the rod main body is drilled and the inner stepped portion. Piston rod. Hollow piston rod according to claim 1, wherein is provided a damping force generating valve device in the hollow portion of the rod body.

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