JP2004197873A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent rattling caused by the impact and vibration of a cap with a simple constitution in a hydraulic shock absorber wherein the gap is held between a piston rod and a joint. <P>SOLUTION: In this hydraulic shock absorber 10 wherein the piston rod 20 is projected from one end of a damper tube 11, the joint 30 is welded on a projecting end of the piston rod 20, and the cap 40 is held between the piston rod 30 and the joint 30, an uneven part 44 is formed on a contact face at the piston rod 20 side, of the cap 40. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic shock absorber.
[0002]
[Prior art]
As described in Patent Document 1, there is a hydraulic shock absorber in which a piston rod is protruded from one end of a damper tube, a joint is welded to the protruding end of the piston rod, and a cap is sandwiched between the piston rod and the joint. .
[0003]
[Patent Document 1]
Japanese Utility Model Sho 61-154340 (1 page, Fig. 1)
[0004]
[Problems to be solved by the invention]
In Patent Document 1, the cap is fixed to the piston rod while being press-fitted into the small-diameter protruding end of the piston rod, and a dust cover is attached to the cap. When an impact or vibration applied to the hydraulic shock absorber is transmitted to the cap or the dust cover, the press-fitting portion of the cap with respect to the piston rod is loosened, and the cap rotates or tilts to gradually generate backlash. This is particularly noticeable when the dust cover is made of heavy metal.
[0005]
To prevent the rattling of the cap, the piston rod, cap and joint are welded together, or the cap and joint are welded after the cap is sandwiched between the piston rod and joint. Some are welded in a reinforcing manner. However, it takes time and effort to weld the cap, which increases the cost.
[0006]
An object of the present invention is to prevent rattling due to impact and vibration of a cap with a simple configuration in a hydraulic shock absorber in which a cap is sandwiched between a piston rod and a joint.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a hydraulic shock absorber in which a piston rod is protruded from one end of a damper tube, a joint is welded to the protruding end of the piston rod, and a cap is sandwiched between the piston rod and the joint. An uneven portion is provided on the contact surface on the side.
[0008]
According to a second aspect of the present invention, in addition to the first aspect of the present invention, a concave-convex portion is also provided on the contact surface on the joint side of the cap.
[0009]
According to a third aspect of the present invention, in the first or second aspect of the present invention, the cap is a press-formed product.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 is a front view showing the entire hydraulic shock absorber, FIG. 2 is a front view showing a rod assembly, FIG. 3 shows a cap clamping structure, (A) is a front sectional view, and (B) is a side sectional view, FIG. 4 shows a cap, (A) is a cross-sectional view, (B) is a plan view, (C) is an enlarged view of a main part, FIG. 5 is a schematic diagram showing an example of a planar shape of an uneven portion provided on the cap, and FIG. It is a schematic diagram which shows the example of the groove shape of the uneven | corrugated | grooved part provided in a cap.
[0011]
As shown in FIG. 1, the hydraulic shock absorber 10 slidably inserts a piston with a damping force generation mechanism into a damper tube 11 and projects a piston rod 20 to which the piston is coupled from one end of the damper tube 11. The joint 30 as the vehicle body side mounting member is welded to the protruding end of the piston rod 20, and the joint 12 as the axle side mounting member is welded to the other end of the damper tube 11.
[0012]
The hydraulic shock absorber 10 has a cap 40 sandwiched between the piston rod 20 and the joint 30, and the upper end of the dust cover 13 is attached or welded to the outer periphery of the cap 40, and the dust cover 13 is attached to the piston rod 20 and the damper tube 11. The piston rod 20 and the damper tube 11 are covered with the dust cover 13 by hanging down along the periphery. The dust cover 13 is made of metal or resin.
[0013]
The hydraulic shock absorber 10 has the following configuration in order to prevent the cap 40 from rattling.
[0014]
The end of the piston rod 20 to which the joint 30 is welded is a small diameter portion 21 into which the cap 40 can be press-fitted, and a welding protrusion (not shown) to the joint 30 is provided at the tip of the small diameter portion 21. The piston rod 20 has a shoulder 23 as a step portion of the small diameter portion 21 with respect to the large diameter portion 22.
[0015]
In the joint 30, a rubber ring 32 is fitted in a hole of an annular (annular in this embodiment) joint metal 31, and a bush 33 is baked and held on the inner periphery of the rubber ring 32.
[0016]
The cap 40 is a press-molded product and has a top surface portion 41 and a side wall portion 42. The cap 40 forms a hole 43 in the central portion of the top surface portion 41 so that the hole 43 of the top surface portion 41 can be press-fitted into the small diameter portion 21 of the piston rod 20. The cap 40 is pressed into the small diameter portion 21 of the piston rod 20, and the lower end surface around the hole 43 of the top surface portion 41 of the cap 40 is brought into contact with the shoulder portion 23 which is a step portion between the small diameter portion 21 and the large diameter portion 22. . The cap 40 allows the upper end portion of the dust cover 13 to be attached or welded to the outer peripheral portion of the top surface portion 41 and the outer side portion of the side wall portion 42.
[0017]
However, as shown in FIG. 4, the cap 40 press-molds the knurled irregularities 44 on the inner surface around the hole 43, which becomes a contact surface with the shoulder 23 of the piston rod 20 during the press-molding process. Provided. The cap 40 has a knurled shape on the outer surface around the hole 43 that becomes a contact surface on the joint metal 31 side of the joint 30 together with or in place of the uneven portion 44 in the press molding process. The uneven portion 45 may be provided by press molding.
[0018]
The concavo-convex portions 44 and 45 are press-molding molds for the cap 40 and can be molded simultaneously with the entire cap 40, and the processing man-hours for the cap 40 do not increase.
[0019]
The structure in which the cap 40 is sandwiched between the piston rod 20 and the joint 30 is as follows.
[0020]
(1) The cap 40 is press-fitted into the small diameter portion 21 of the piston rod 20. The lower end surface around the small diameter portion 21 of the cap 40 is brought into contact with the shoulder portion 23.
[0021]
(2) The projection for welding at the tip of the small diameter portion 21 into which the cap 40 of the piston rod 20 is press-fitted is abutted against the outer peripheral surface of the joint 30 (joint metal 31), and projection welding is performed (FIG. 2). At this time, by energizing the joint 30 while pressing the joint 30 against the piston rod 20, the cap 40 is pressed against the shoulder 23 of the piston rod 20 and is clamped and fixed between the joint 30 and the piston rod 20. The welding current flows between the piston rod 20 and the joint 30, and the cap 40 is not welded to either the piston rod 20 or the joint 30.
[0022]
(3) When the piston rod 20 and the joint 30 are welded in the above (2), the piston rod 20 and the joint 30 are melted or softened by heat. On the piston rod 20 side of the cap 40, the softened piston rod 20 bites into the concavo-convex portion 44 on the inner surface of the cap 40 like the biting portion 24 (FIG. 3). Further, on the joint 30 side of the cap 40, the softened piston rod 20 and / or the softened joint 30 bite into the uneven portion 45 on the outer surface of the cap 40 like the biting portion 25 (FIG. 3). Thereby, the cap 40 is firmly fixed by both the piston rod 20 and the joint 30.
[0023]
In addition, the form of the uneven | corrugated | grooved part 44 (45) in the cap 40 is a grid | lattice form (FIG. 5 (A)), a parallel line form (FIG. 5 (B)), a dotted line form (FIG. 5 (C)), and many point forms (FIG. 5D), radial (not shown), numerous protrusions (not shown), random (not shown), and the like. The grooves 44 (45) have a trapezoidal groove shape (FIG. 6A), a triangular groove shape (FIG. 6B), an arc groove shape (FIG. 6C), and a right triangular groove shape (see FIG. 6). 6 (D)). The depth of the knurled concave portion of the uneven portion 44 (45) may be about 0.2 mm to 0.5 mm.
[0024]
According to this embodiment, there are the following effects.
(Operational effect corresponding to claim 1)
(1) Since the concave and convex portion 44 is provided on the contact surface of the cap 40 with the piston rod 20, when the joint 30 is pressed against the protruding end of the piston rod 20 and welded, the gap is provided between the piston rod 20 and the joint 30. The concavo-convex portion 44 of the cap 40 sandwiched between bites into the shoulder portion 23 of the piston rod 20. This increases the biting force in the rotational direction and the axial direction of the cap 40 with respect to the piston rod 20 at the press-fitting portion of the cap 40 into the piston rod 20, and makes the cap 40 stronger in the rotational direction and the withdrawal direction with respect to the piston rod 20. To prevent rattling from shocks and vibrations. Without any special welding of the cap 40, it is possible to prevent rattling due to impact and vibration of the cap 40 with a simple configuration.
[0025]
(Function and effect corresponding to claim 2)
(2) If the concave / convex portion 45 is also provided on the contact surface of the cap 40 on the joint 30 side, the concave / convex portion 45 of the cap 40 also bites into the joint 30 side in the above-mentioned (1). The cap 40 can be held more firmly in both the rotational direction and the withdrawal direction with respect to both the piston rod 20 and the joint 30, and rattling due to impact and vibration can be further prevented.
[0026]
(Function and effect corresponding to claim 3)
(3) By using the cap 40 as a press-molded product, the concave and convex portions 44 and 45 can be simultaneously molded when the cap 40 is molded.
[0027]
The embodiment of the present invention has been described with reference to the drawings. However, 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 scope of the present invention. Are also included in the present invention.
[0028]
【The invention's effect】
According to the present invention, in the hydraulic shock absorber in which the cap is sandwiched between the piston rod and the joint, it is possible to prevent rattling due to the impact and vibration of the cap with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a front view showing an entire hydraulic shock absorber.
FIG. 2 is a front view showing a rod assembly.
3A and 3B show a cap sandwiching structure, in which FIG. 3A is a front sectional view and FIG. 3B is a side sectional view.
4A and 4B show a cap; FIG. 4A is a cross-sectional view, FIG. 4B is a plan view, and FIG.
FIG. 5 is a schematic diagram illustrating an example of a planar shape of a concavo-convex portion provided in a cap.
FIG. 6 is a schematic diagram showing an example of the groove shape of the uneven portion provided in the cap.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Hydraulic buffer 11 Damper tube 20 Piston rod 30 Joint 40 Cap 44, 45 Uneven part

Claims (3)

In the hydraulic shock absorber, the piston rod is protruded from one end of the damper tube, the joint is welded to the protruding end of the piston rod, and the cap is sandwiched between the piston rod and the joint.
A hydraulic shock absorber, wherein a concave and convex portion is provided on a contact surface on the piston rod side of the cap. The hydraulic shock absorber according to claim 1, wherein an uneven portion is also provided on a contact surface on the joint side of the cap. The hydraulic shock absorber according to claim 1 or 2, wherein the cap is a press-formed product.

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