JP2001020990A - Piston assembly structure of hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure connecting strength by running off from an imperfect screw part of a piston rod at the time of connecting a piston assembly body to the piston rod by a piston nut. SOLUTION: A running off part 17 extended in diameter along a fastening seat surface 14 from a part opposed to an imperfect screw part 15 of a male screw 11 of a piston rod 1 and not to be screwed on each other is provided on an inside diametrical part on the base end side of a female screw 16 of a piston nut 12 to prevent tightening force from becoming insufficient as the female screw 16 of the piston nut 12 is hooked on the imperfect screw part 15 made on a base end of the male screw 11 of a small diametrical part 2 at the time of integrally connecting a piston assembly body 10 to the piston rod 1 by fastening it with the piston nut 12 by inserting the piston assembly body 10 in the small diametrical part 2 on the head end of the piston rod 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a structure for assembling a piston of a hydraulic shock absorber when a piston assembly is fastened to a tip of a piston rod with a piston nut, and also relates to a method of reducing a depression of a piston. The present invention relates to an improvement in a structure for assembling a piston of a hydraulic shock absorber of this kind, which can be assembled while centering while suppressing an extension damping valve housed inside from outside.

[0002]

2. Description of the Related Art Conventionally, when assembling a hydraulic shock absorber of this kind, as shown in FIG. 5 attached thereto, a piston assembly 10 temporarily assembled to a small diameter portion 2 extending concentrically from the tip of a piston rod 1 is used. Insert the piston nut 12
The piston assembly 1 is tightened by screwing
0 is the step 13 of the piston rod 1 and the piston nut 12
And is fixed by being clamped between the fastening seat surfaces 14.

Further, in this case, in order to improve the working efficiency at the time of assembling the hydraulic shock absorber, as shown in FIG. , 7 and the valve stoppers 8, 9 are sequentially stacked and temporarily assembled, and the piston assembly 10 is inserted into each holding needle called a needle tip 18 and transported to a place where the piston rod 1 is assembled.

[0004] Here, the piston rod assembler grasps the piston assembly 10 which has been transported by being inserted into the needle mountain 18 in a temporarily assembled state, and removes the piston assembly 10 from the needle mountain 18 as shown in FIG. A piston nut 12 is screwed into the male screw 11 of the small-diameter portion 2 from above in place of the small-diameter portion 2 at the tip of the piston rod 1, and the piston assembly 10 is connected to the shoulder 13 of the piston rod 1 and the tightening seat surface 14 of the piston nut 12. And fix it.

[0005]

Therefore, when the male screw 11 for screwing the piston nut 12 from the distal end of the small diameter portion 2 of the piston rod 1 to the middle is to be cut, the male screw 11 of the male screw 11 Inevitably, an incomplete screw portion (incomplete screw portion) 15 is formed at one end.

For this purpose, the small diameter portion 2 of the piston rod 1
If the female screw 16 of the piston nut 12 is applied to the incomplete threaded portion 15 when attaching the piston assembly 10 to the piston assembly 10, the piston assembly 10 cannot be tightened with the piston nut 12 with sufficient tightening force. .

Therefore, in order to avoid this, the male screw 11 cut into the small diameter portion 2 at the tip of the piston rod 1 is made long,
The internal thread 16 of the piston nut 12 is prevented from reaching the incomplete thread portion 15, or the spacers 6, 7 and the valve stoppers 8, 9 of the piston assembly 10 are made thicker, and the distal spacer 6 and the valve It is conceivable that the inner peripheral surface of the stopper 8 covers the incomplete screw portion 15.

However, the piston nut 1 for fixing the piston assembly 10 to the small-diameter portion 2 of the piston rod 1
In the case of No. 2, it is necessary to crush the tip of the male screw 11 after assembling and perform a crimping process for preventing loosening.

At this time, the small diameter portion 2 of the piston rod 1
The length of the male screw 11 cut into the
Large force is required when performing crimping work by crushing the tip of the cylinder.In practice, it is difficult to reliably crush the cylinder. The shortage of the basic length of the vessel occurs, which in turn lengthens the piston rod 1 and is disadvantageous in cost.

Therefore, in order to prevent the female screw 16 of the piston nut 12 from catching on the incomplete threaded portion 15 at the small diameter portion 2 at the tip of the piston rod 1, the inner peripheral surface of the spacer 6 and the valve stopper 8 is required. For this reason, the thickness of the spacer 6 and the valve stopper 8 is increased to increase the cost, and the basic length of the hydraulic shock absorber is reduced. On the other hand, a sufficient stroke cannot be obtained.

Further, when assembling the piston assembly 10 to the piston rod 1, the needle assembly 18
When the piston assembly 10 is removed from the needle ridge 18 and there is a radial misalignment between the components of the piston assembly 10 in the radial direction, the piston assembly 10 is replaced with the small-diameter portion 2 of the piston rod 1 when the piston assembly 10 is replaced. Misalignment hinders assembly time.

Therefore, the assembling operator pulls the valve stopper 9 of the compression-side damping valve 5 with the fingertip while grasping the outer periphery of the piston 3 with the belly of the finger, and presses the compression-side damping valve 5 against the piston 3 through the spacer 7. The pressure-side damping valve 5 and the spacer 7 and the valve stopper 9 are removed from the needle peak 18 so as not to be misaligned with respect to the piston 3.

However, this is very similar to the depression 2 of the piston 3.
The expansion damping valve 4 and the spacer 6 and the valve stopper 8 housed in the inside 1 have no means for restricting misalignment with respect to the piston 3, so that there is no means for regulating the misalignment with respect to the piston 3. It cannot prevent misalignment.

Therefore, when the piston assembly 10 is replaced from the needle tip 18 to the piston rod 1, the extension side damping valve 4, the spacer 6 and the valve stopper 8 move to cause misalignment between the piston 3 and the piston. As a result, there is an inconvenience that the assemblability of the piston assembly 10 to the small diameter portion 2 at the tip of the piston rod 1 becomes extremely poor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to avoid an incompletely threaded portion of a piston rod with a simple structure without increasing the length of a male screw cut in the small diameter portion of the piston rod or extending the basic length of the piston assembly. In addition, it is necessary to secure the coupling strength of the piston assembly to the piston rod, and at the same time, when the piston assembly is removed from the needle ridge, a misalignment occurs between the members, and the piston assembly is An object of the present invention is to provide a hydraulic shock absorber piston assembling structure capable of easily removing troubles in assembling.

[0016]

SUMMARY OF THE INVENTION The object of the present invention is to insert a piston assembly into a small-diameter portion at the tip of a piston rod and tighten the piston assembly with a piston nut. In order to prevent insufficient tightening force due to the internal thread of the piston nut being applied to the incomplete thread part formed at the base end of the male thread of the small diameter part when the three-dimensional body is integrally joined, This is achieved by forming the inner diameter portion on the proximal end side of the female screw from a portion facing the incompletely threaded portion of the male screw of the piston rod to a relief portion which does not screw with each other by expanding in diameter from the portion facing the tightening seat surface.

That is, with such a configuration, the relief portion formed by hollowing out the female screw portion on the side of the tightening seat when the tightening of the piston nut is completed, allows the male screw in the small-diameter portion at the tip of the piston rod to be formed. The incompletely threaded portion at the small diameter portion at the tip of the piston rod facing the incompletely threaded portion escapes meshing with the internal thread of the piston nut.

Therefore, by maintaining the effective length of engagement between the male screw and the female screw of the piston nut at the small diameter portion at the tip of the piston rod, the small diameter portion of the piston rod is not completely formed on the inner peripheral surface of the spacer and the valve stopper. Since it is not necessary to cover the threaded portion, it is possible to keep the thicknesses of the spacers and the valve stopper thin and to prevent the basic length of the hydraulic shock absorber from being increased.

In addition, since the thickness of the valve stopper can be reduced as described above, the valve stopper does not need to be formed as a sintered component, and can be made of a press-processable steel plate. In addition, the cost will be reduced.

Another object of the present invention is to provide a piston assembly in which a piston nut and a temporarily assembled piston assembly are overlapped and inserted, as in the second aspect of the present invention, in addition to the first aspect of the present invention. The outer diameter and the axial length of the needle for transportation to be transported to the mounting position on the rod are adjusted to the first rod portion that matches the height and the inner diameter of the piston assembly, and the piston is made smaller in diameter than the first rod portion. This can be more effectively achieved by forming the second rod portion in two steps having an outer diameter that matches the height of the nut and the thread diameter of the internal thread.

That is, according to the second aspect of the present invention, the piston assembly is inserted into the first rod portion of the needle ridge, and the piston nut is placed on the second rod portion, which is thinner than the first rod portion. I will insert it into the rod part.

Thus, the piston assembly is centered at the first rod portion of the needle ridge, and the piston assembly and the piston nut are centered at the first and second rod portions of the needle ridge. In addition, a part of the piston nut protrudes outward from the inside of the recess of the piston in the axial direction.

Accordingly, when the valve stopper of the compression damping valve is pulled with the fingertip while grasping the outer periphery of the piston with the belly portion of the finger, and the piston assembly is to be pulled out from the first rod portion of the needle mountain, the piston nut Will hit the palm of the hand and push the piston assembly against the bottom of the piston recess to keep it from moving.

Therefore, the piston assembly that has been carried by being inserted into the needle ridge is gripped by the operator while holding the outer periphery of the piston at the abdomen of the finger, and sandwiching the piston assembly and the piston nut between the fingertip and the palm. The assembly and the piston nut can be taken out of the needle ridge while being kept together.

Thus, it is possible to prevent the piston nut from being misaligned with the piston as well as the valve stoppers on the extension side and the compression side of the piston assembly and the spacers, respectively. This makes it possible to remove the needle rod from the needle ridge while maintaining good attachment to the piston rod.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piston mounting structure of a hydraulic shock absorber according to an embodiment of the present invention will be described below with reference to FIG. 1 attached to the specification.

The above-described structure for assembling the piston of the hydraulic shock absorber comprises a small-diameter portion 2 extending concentrically from one end of the piston rod 1 and extension-side and compression-side damping valves 4 and 5 on both sides of the piston 3. And a piston assembly 10 in which the spacers 6, 7 and the valve stoppers 8, 9 are temporarily assembled.

The piston assembly 10 provided with the above temporary assembly
Is inserted into the small diameter portion 2 of the piston rod 1 from the distal end side, and then the male screw 1 cut into the small diameter portion 2 from above is inserted.
By screwing a piston nut 12 into the piston rod 1, the piston assembly 10 is connected to the shoulder 1 of the piston rod 1.
3 and the clamping seat surface 14 of the piston nut 12 for fixing.

In this case, the piston nut 12 is attached to the imperfect thread 15 of the small diameter portion 2 at the tip of the piston rod 1.
When the internal thread 16 of the piston rod 1 is engaged, the piston assembly 10 is
As a result, it is not possible to tighten with a sufficient tightening force.

Therefore, in the embodiment of FIG. 1, when the piston assembly 10 is fastened and fixed to the small diameter portion 2 at the tip of the piston rod 1 with the piston nut 12, the small diameter portion 2 From the portion of the male screw 11 facing the incompletely threaded portion 15 in the piston nut 1
The inner diameter portion of the female screw 16 over the second tightening seat surface 14 is enlarged in diameter to form a relief portion 17 that does not screw together.

With this configuration, when the tightening of the piston nut 12 is completed, the female screw 1 on the tightening seat surface 14 side
An escape portion 17 formed by hollowing out the portion 6 faces the incomplete thread portion 15 of the male screw 11 in the small diameter portion 2 at the tip of the piston rod 1, and an incomplete thread portion in the small diameter portion 2 at the tip of the piston rod 1. 15 escapes meshing with the internal thread 16 of the piston nut 12.

Accordingly, by maintaining the effective length of engagement between the male screw 11 and the female screw 16 of the piston nut 12 in the small diameter portion 2 at the tip of the piston rod 1, the piston 6 is formed on the inner peripheral surface of the spacer 6 and the valve stopper 8. Since it is not necessary to cover the incomplete threaded portion 15 of the small diameter portion 2 of the rod 1, the thickness of the spacer 6 and the valve stopper 8 is not increased, and the basic length of the hydraulic shock absorber is kept as small as possible. It can be prevented from becoming longer.

Further, since the thickness of the valve stopper 8 can be reduced as described above, it is not necessary to configure the valve stopper 8 as a sintered part. It can also reduce costs.

When assembling the hydraulic shock absorber, it is preferable to perform the assembly by using a work flow in order to improve work efficiency. This is also true for the assembly of the piston assembly 10 to the piston rod 1. This is no exception.

Therefore, in the present invention, the temporarily assembled piston assembly 10 is assembled to the small diameter portion 2 of the piston rod 1 together with the piston nut 12, as in the embodiment shown in FIG. .

That is, the piston assembly 10 temporarily assembled with the piston nut 12 is vertically stacked and
The outer diameter and the axial length of the transfer needle ridge 18 to be transported to the assembling location are adjusted to the height and the inner diameter of the piston assembly 10 by using a first rod portion 19 and a first rod portion 19. The second rod portion 20 having a small diameter and an outer diameter adapted to the height of the piston nut 12 and the diameter of the female screw 16 is formed in two stages.

The extension-side and compression-side damping valves 4 and 5, the spacers 6 and 7, and the valve stoppers 8 and 9 are sequentially stacked with the piston 3 interposed therebetween, and temporary assembly is performed in this manner. The piston assembly 10 is inserted into and held by the first rod portion 19 of the needle tip 18, and the piston nut 12 is inserted into the second rod portion 20 having a smaller diameter than the first rod portion 19 from above.

As a result, the first rod portion 19 of the needle tip 18 centers the members constituting the piston assembly 10 and the first and second rod portions 19,
At 20, the piston assembly 10 and the piston nut 12 can be centered, and in addition, part of the piston nut 12 projects axially from inside the recess 21 of the piston 3.

Therefore, when taking out the piston assembly 10 and the piston nut 12 from the needle tip 18, the valve stopper 9 of the pressure-side damping valve 5 is pulled with the fingertip while grasping the outer periphery of the piston 3 with the abdomen of the finger. The three-dimensional body 10 and the piston nut 12 are withdrawn from the needle tip 18.

At this time, at the same time, the upper surface of the piston nut 12 comes into contact with the palm of the hand.
And the spacer 6 and the valve stopper 8 are pressed against the bottom of the recess 21 of the piston 3 so as not to move.

Thus, the piston nut 1 as well as the extension and compression damping valves 4 and 5 and the spacers 6 and 7 and the valve stoppers 8 and 9 of the piston assembly 10 are provided.
While aligning 2 with the piston assembly 10,
This makes it possible to remove the piston assembly 10 from the needle peak 18 while keeping the assemblability of the piston assembly 10 to the piston rod 1 good.

1 and 2 described above.
In this embodiment, the valve soots 8 and 9 are provided for both the extension side and the compression side damping valves 4 and 5, however, as in the other embodiments shown in FIGS. 3 and 4, The tightening seat surface 14 of the piston nut 12 may be used to replace the valve stopper 8 of the extension-side damping valve 4.

[0043]

As described above, according to the first aspect of the present invention, the piston assembly is inserted into the small-diameter portion at the tip of the piston rod and tightened with the piston nut to integrally connect the piston assembly to the piston rod. In order to prevent the female screw of the piston nut from being applied to the incomplete thread part formed at the proximal end of the male screw of the small diameter part, the tightening force becomes insufficient, The effective inner length of the piston nut is increased by forming the inner diameter portion as a relief portion that does not screw with each other by expanding the diameter from the portion facing the incomplete thread portion of the external thread of the piston rod to the tightening seat surface. Thus, the tightening force of the piston assembly can be increased.

According to the second aspect of the present invention, in addition to the above, a needle needle for transporting a piston assembly and a mounting piston nut to be stacked and carried to a mounting position on a piston rod is provided by the piston assembly. Formed in two stages: a first rod part that fits the height and inner diameter, and a second rod part that has a smaller diameter than this first rod part and an outer diameter that matches the height of the piston nut and the thread diameter of the internal thread By removing the piston assembly from the needle ridge, the center gap between each member can be suppressed with the piston nut, and the thickness of the spacer and valve stopper can be reduced. The length can be shortened.

Furthermore, since the thickness of the valve stopper can be reduced, the valve stopper does not need to be formed as a sintered part, and can be made of a press-processable steel plate. Also.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a state where a piston assembly, which is a structure for assembling a piston of a hydraulic shock absorber according to the present invention, is attached to a piston rod with a piston nut. It is a front view shown in longitudinal section.

FIG. 2 is a longitudinal sectional front view showing a state in which the piston assembly and the piston nut are inserted into and held by a needle for alignment.

FIG. 3 is a longitudinal sectional front view showing a state where a piston assembly, which is a piston assembly structure according to another embodiment of the present invention, is attached to a piston rod with a piston nut.

FIG. 4 is a longitudinal sectional front view showing a state in which the piston assembly and the piston nut are inserted and held in a needle for alignment in the same manner.

FIG. 5 is a longitudinal sectional front view showing a state in which a piston assembly, which is a conventional piston mounting structure of a hydraulic shock absorber, is attached to a piston rod with a piston nut.

FIG. 6 is a longitudinal sectional front view showing a state in which the piston assembly is inserted and held in a needle ridge for centering.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston rod 2 Small diameter part 3 Piston 10 Piston assembly 11 Male screw 12 Piston nut 14 Tightening seat surface 15 Incomplete screw part 16 Female screw 17 Relief part 18 Needle mountain 19 First rod part 20 Second rod part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H081 AA03 BB02 CC20 EE27 3J044 AA18 DA10 3J069 AA50 CC15 DD47 EE05 EE28

Claims (2)

[Claims] When the piston assembly is inserted into a small-diameter portion at the distal end of a piston rod and fastened with a piston nut to integrally connect the piston assembly to the piston rod, an incomplete portion formed at the proximal end of the male screw of the small-diameter portion is formed. To prevent insufficient tightening force due to the internal thread of the piston nut being applied to the threaded portion, the inner diameter portion on the proximal end side of the internal thread of the piston nut faces the incompletely threaded portion of the external thread of the piston rod. A piston assembling structure for a hydraulic shock absorber, characterized in that the diameter of the piston is increased from the portion to the tightening seat surface so that the escape portion does not screw together. 2. An outer diameter and an axial length of a needle for transporting a piston nut and a temporarily assembled piston assembly which are carried to a place where the piston nut is assembled to a piston rod while being fitted and inserted into the piston assembly. A first rod portion that fits the height and inner diameter of the first rod portion, and a second rod portion that has a smaller diameter than this first rod portion and an outer diameter that matches the height of the piston nut and the thread diameter of the internal thread. The piston assembling structure of the hydraulic shock absorber according to claim 1 formed.