JPH09317811A - Bump stopper locking structure in hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a cap and reduce costs by forming a radial projective thread under a bump stopper and the projective thread is electric resistance welded to the caulking part of and upper end of an outer casing in a hydraulic shock absorber holding a bump stopper at the upper end of the outer casing for regulating the attaching length at a maximum shrinking state. SOLUTION: In a hydraulic shock absorber mounted between a car body and a wheel, a piston valve is attached to a piston rod assembly 1, cylinder is stored in an outer casing 3, an oil seal 4 is engaged from the upper part of the outer casing, thereafter the upper ends of the outer casing is sealed by caulking. A bump stopper 106 for regulating the attaching length at maximum shrinking state of a piston rod assembly 1 is press fitted to an outer periphery of an upper end of the outer casing 3. In order to fix the bump stopper 106, a radial projection thread 106A is provided under one disk, the peak of the tip is seated to a caulking part 3A of the outer casing 3, thereafter a current is made to flow in the seated part to thereby melt the seated part for integration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber for suppressing vibration of a vehicle body such as a suspension system of an automobile, and more particularly, to an improvement of a bump stopper locking structure for restricting a mounting length when the bumper is contracted. Is.

[0002]

2. Description of the Related Art FIG. 5 is a vertical sectional view of a hydraulic shock absorber having a conventional bump stopper. Generally, a hydraulic shock absorber mounted between a vehicle body and wheels via a coupling member is
Piston valve assembly 1 has piston valve PV
The cylinder 2 having the rod guide 5 mounted on the upper end and the base valve BV mounted on the lower end is housed in the outer cylinder 3 and the oil seal 4 for shutting off the outside air is attached to the outer cylinder 3. After fitting from the upper part, the upper end of the outer cylinder 3 is formed by caulking and sealing. A tank chamber C is formed between the cylinder 2 and the outer cylinder 3.

The oil seal 4 is an inner peripheral seal portion 4A for sealing the sliding surface with the piston rod assembly 1.
And an outer peripheral seal portion 4C for sealing the fitting surface between the rod guide 5 and the outer cylinder 3 on the inner and outer peripheral portions of the insert metal 4B.
It is formed physically, and the compressive force due to the crimping of the upper end of the outer cylinder is applied to the built-in parts via the insert metal 4B.

When the piston rod assembly 1 rises in the cylinder 2 filled with hydraulic oil, the sealed hydraulic oil in the piston upper chamber A flows into the piston lower chamber B via the piston valve PV. The passage resistance at this time becomes the extension side damping force. The hydraulic oil corresponding to the withdrawal volume that is insufficient due to the rise of the piston rod assembly 1 is sucked from the tank chamber C via the suction valve attached to the base valve BV arranged at the lower end of the cylinder 2.

On the contrary, when the piston rod assembly 1 descends in the cylinder 2, the hydraulic oil in the sealed piston lower chamber B is replenished in the piston upper chamber A through the outer peripheral side circulation passage of the piston. Except base valve B
It flows into the tank chamber C via V. The passage resistance at this time becomes the compression side damping force.

A bump stopper 6 for restricting the mounting length of the piston rod 1 at the most contracted time (hereinafter referred to as the most contracted length) is press-fitted to the outer periphery of the upper end of the outer cylinder 3. The bump stopper 6 includes a bump plate 6A with which a cushion rubber (not shown) supported on the piston rod abuts,
A cap 6B that supports the bump plate 6A on the outer cylinder 3 is integrally coupled by projection welding or the like.

[0007]

As described above, in the bump stopper 6, the bump plate 6A and the cap 6B are integrally joined by welding or the like. Since it is necessary to connect the two in a concentric manner, a highly accurate welding jig is required, and maintenance costs such as maintenance of welding conditions are constantly generated, and because it is composed of two parts, the material There has been a problem that both cost and weight increase, resulting in high cost.

Further, the cap 6B is press-fitted and supported on the outer periphery of the upper end of the outer cylinder 3, so that a process such as ball threading for finishing the inner diameter with high accuracy is indispensable, and when the outer diameter of the outer cylinder is different, it is adjusted accordingly. It has to be done, and this has also been a factor of increasing costs. Further, if an excessive bump load is applied, there is a risk that the cap 6B and the press-fitting fitting portion of the outer cylinder 3 may be loosened and separated from each other.

The present invention has been made in view of the above circumstances, and an object thereof is to form a ridge or a protrusion on the lower surface of the bump stopper so that the caulking portion 3A at the upper end of the outer cylinder is formed. The purpose of the present invention is to provide a bump stopper locking structure in which a seat 6 is supported and is supported by the outer cylinder 3 by welding with a large current flowing through the seat, and the cap 6B is eliminated.

[0010]

In order to solve the above-mentioned problems, the first means adopted by the present invention is an outer cylinder of which the upper end is crimped and sealed in order to regulate the mounting length at the time of contraction. In a hydraulic shock absorber having a bump stopper at its upper end, a radial projection is formed on the lower surface of a disk-shaped bump stopper, and the projection is electrically resistance welded to the crimped portion at the upper end of the outer cylinder. is there. The second means is to provide a large and small bowl-shaped projection on the lower surface concentric circle of the disk-shaped bump stopper, and the large bowl portion secures a gap between the lower surface of the bump stopper and the crimped portion at the upper end of the outer cylinder. The small bowl part is an electric resistance welded part to the caulking part at the upper end of the outer cylinder. The third means is an oil that shuts off the outside air by slidably accommodating the piston rod assembly with the piston valve assembled therein, accommodating the cylinder with the rod guide at the upper end and the base valve at the lower end in the outer cylinder. In a hydraulic shock absorber in which a bump stopper is supported by electric resistance welding on a crimped portion on the upper end of the outer cylinder where the upper end of the outer cylinder is sealed by crimping with a seal or the like interposed therebetween,
That is, an oil seal for blocking outside air and a spacer for receiving a caulking load are superposed on the upper side of the rod guide. When the hydraulic shock absorber has the above-described structure, the protruding height of the radial projections on the lower surface of the bump stopper of the first means is lowered, and the bowl-shaped projections of two steps, large and small, on the lower surface of the bump stopper of the second means are reduced to one step. Use small protrusions to reduce the protrusion height.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a structure of a bump stopper of a hydraulic shock absorber according to the present invention will be described with reference to a first embodiment shown in FIG. The same parts as those of the conventional technique shown in FIG. 5 are designated by the same reference numerals, and the description of the parts not particularly necessary is omitted. The greatest feature of the bump stopper 106 according to the present invention is that, as shown in FIG. 1 (B), at least three radial projections 106A are arranged under a single disc in a substantially equal manner.
Is provided. As shown in FIG. 1C, the ridge has a sharp tip, and is positioned and seated concentrically in a state of partial line contact with the tightenable portion 3A of the outer cylinder 3.

When a large current is passed between the outer cylinder 3 and the bump stopper 106 for a short time in the state where it is seated on the caulking portion 3A, the current concentrates on the seating portion, and the contact resistance and the squared value of the current The seating portion is melted and integrated by the Joule heat proportional to the product. Capacitor welding is the most suitable welding method in which a large current is passed in a short time to concentrate the heat generated during welding in the vicinity of the welded portion and to reduce the heat-affected area. Other welding methods may be used as long as it can be ensured that the circumferential seal portion 4A is not damaged by welding heat. The load applied to the bump stopper 106 is applied in the axial direction of the hydraulic shock absorber, and there is almost no risk of the welded portion peeling off. Therefore, the welded portion may be small.

Here, the protrusion 10 of the bump stopper 106
6A will be described in detail. The upper end of the inner peripheral seal portion 4A of the oil seal 4 swings following the flexure of the piston rod 1 due to the external input, while maintaining the tension on the sliding surface of the piston rod. Therefore, in order to secure the space 106D on the lower surface of the bump stopper, the ridge 106A is formed so as to avoid the upper end portion of the inner peripheral seal portion 4A. Therefore, the dust that enters from the upper surface of the bump stopper 106 through the gap between the inner diameter d _{0 of the} bump stopper and the outer diameter d of the piston rod is in the space 106D.
Through the passage 106C formed on the lower surface of the flat plate portion 106B of the bump stopper.

Bump stopper ridge 106A and flat plate portion 1
Since it is smoothly connected to 06B, even if the lower end of the cushion rubber (not shown) collides with the upper surface, the durability of the cushion rubber does not pose a practical problem, and the protrusions 106A prevent the bump stopper from being deformed. The rigidity with respect to can be increased. Further, even when the outer diameter d of the piston rod is the same and the outer diameter D ₀ of the outer cylinder 3 is different, only the diameter of the crimp portion 3A is different, and the protrusion 106A of the bump stopper has the same diameter as the crimp portion 3A. Since it can be seated regardless of size, the bump stopper can be used in common. In the case of the prior art, the cap was set according to the outer diameter of the outer cylinder, but in the case of the present embodiment, the cap itself can be omitted, so that the cost can be greatly reduced.

Next, a second embodiment of the present invention shown in FIG. 2 will be described. The difference from the first embodiment shown in FIG. 1 is that
It is on a bowl-shaped projection 206A for sitting on the crimping portion 3A of the bump stopper 206. The bowl-shaped projection 206A for the seating
Are arranged on the circumference in approximately equal parts and at least three are arranged to be seated on the caulking portion 3A. In this state, when a large current is passed between the outer cylinder 3 and the bump stopper 206 for a short time, the current concentrates on the seated portion as in the first embodiment, and the Joule heat proportional to the product of the contact resistance and the square value of the current. As a result, the seated portion is melted and integrated.

In this embodiment, a small bowl portion 206B having a small heat capacity is projected from the lower end portion of the large bowl portion 206A in order to improve the current concentration and ensure the melting of the seat portion. Since the large bowl portion 206A has a large heat capacity and is difficult to melt, it becomes easy to secure a dimension between the bump stopper lower surface 206C and the crimp portion 3A. Dust that enters from the upper surface of the bump stopper 206 through the gap between the inner diameter d _{0 of the} bump stopper and the outer diameter d of the piston rod passes through the space between the protrusions 206A and is discharged to the outside.

By the way, in the case of the above-described first embodiment, the ridge 106A needs to have such a height that at least the upper end of the inner peripheral seal portion 4A and the lower surface of the bump stopper do not interfere with each other. If the upper surface of the bump stopper on which 106A is formed has a deep recess and the lower end of the cushion rubber (not shown) collides with the upper surface of the bump stopper, there is a concern that the durability of the cushion rubber will be reduced.

The third embodiment of the present invention shown in FIG. 3 is an improvement of this. The difference from the first embodiment shown in FIG. 1 is that an oil-oil seal 4 that shuts off the outside air and a spacer 301 that receives a caulking load are superposed on the rod guide 5 of the hydraulic shock absorber, and the outer cylinder is inserted. That is, the upper end portion of was sealed by crimping. Since the upper surface of the caulking portion 3A rises above the upper end of the inner peripheral seal portion 4A of the oil seal 4 by the thickness of the spacer, the height of the protrusion 306A on the lower surface of the bump stopper can be reduced accordingly. it can.
Therefore, since the recess 306B on the upper surface of the bump stopper 306 becomes shallower, the durability of the cushion rubber can be improved when the lower end of the cushion rubber (not shown) collides with the upper surface of the bump stopper 306.

When the structure of the hydraulic shock absorber is the same as that of the third embodiment, the bump stopper of the second embodiment described above also has a simpler shape. The fourth embodiment of the present invention shown in FIG. 4 shows this. Since the upper surface of the caulking portion 3A rises above the upper end of the inner peripheral seal portion 4A of the oil seal 4 by the thickness of the spacer 301, the height of the protrusion 406A on the lower surface of the bump stopper can be reduced by that amount. As a result, the protrusion shape becomes smaller. Therefore, the bump stopper 4
Since the recess 406B on the upper surface of 06 becomes shallower, the protrusion 406
A can be formed in one step, and the durability of the cushion rubber can be improved when the lower end of the cushion rubber (not shown) collides with the upper surface of the bump stopper 406.

Also in the case of the third or fourth embodiment, when the ridge 306A or the protrusion 406A on the lower surface of the bump stopper and the caulking portion on the upper end of the outer cylinder are resistance-welded, the welding heat is generated via the spacer 301. Because it is transmitted to the seal 4,
The oil seal 4 is less likely to be damaged by welding heat,
The welding method can be easily selected. Further, since the spacer 301 bears the compressive load due to the crimping of the upper end of the outer cylinder, it is possible to properly maintain the residual axial force after crimping by selecting the thickness and material of the spacer 301. It is possible to prevent rattling.

[0021]

As described above in detail, in the present invention,
Since the bump stopper is supported on the outer cylinder by being directly welded to the caulking portion of the outer cylinder of the hydraulic shock absorber, the cap used in the conventional technique can be eliminated. Therefore, the material cost of the cap, the manufacturing cost, the physical distribution cost, the welding cost, etc. can be eliminated, so that the cost can be largely reduced and the weight of the bump stopper can be reduced. In addition, since the bump stopper is directly welded to the outer cylinder of the hydraulic shock absorber, there is no fear of separation between the two. Further, an oil seal for shutting off the outside air and a spacer for receiving a caulking load are superposed on the upper side of the rod guide of the hydraulic shock absorber, and the upper end portion of the outer cylinder is caulked and sealed, whereby a protrusion on the lower surface of the bump stopper is formed. Since the height can be formed low, the manufacture of the bump stopper and the selection of the welding method can be facilitated, and the durability of the cushion rubber can be improved.

[Brief description of the drawings]

FIG. 1A is a vertical sectional view of a hydraulic shock absorber equipped with a bump stopper according to a first embodiment of the present invention. FIG. 3B is a top view of the bump stopper according to the first embodiment. FIG. 6C is a front view of the protrusion on the lower surface of the bump stopper according to the first embodiment.

FIG. 2A is a longitudinal sectional view of a hydraulic shock absorber equipped with a bump stopper according to a second embodiment of the present invention. FIG. 6B is a top view of the bump stopper according to the second embodiment.

FIG. 3A is a vertical sectional view of a hydraulic shock absorber equipped with a bump stopper according to a third embodiment of the present invention. FIG. 9B is a top view of the bump stopper according to the third embodiment. (C) It is a front view of a protrusion on the lower surface of the bump stopper according to the third embodiment.

FIG. 4A is a vertical cross-sectional view of a hydraulic shock absorber equipped with a bump stopper according to a fourth embodiment of the present invention. FIG. 7B is a top view of the bump stopper according to the fourth embodiment.

FIG. 5 is a vertical cross-sectional view of a hydraulic shock absorber equipped with a bump stopper according to a conventional technique.

[Explanation of symbols]

 PV Piston valve BV Base valve 1 Piston rod assembly 2 Cylinder 3 Outer cylinder 3A Caulking part 4 Oil seal 5 Rod guide 106, 206, 306, 406 Bump stopper 106A Radial ridge 206A Bowl-shaped protrusion large portion 206B Bowl-shaped protrusion Small bowl part 301 Spacer 406A protrusion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Hidaka 2-4-1, Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd.

Claims (4)

[Claims] 1. A hydraulic shock absorber in which a bump stopper is held at the upper end of an outer cylinder whose upper end is crimped to regulate the mounting length at the minimum contraction. A bump stopper locking structure in a hydraulic shock absorber, characterized in that a radial projection is formed on the outer surface of the outer cylinder and the projection is electrically resistance welded to a caulking portion at the upper end of the outer cylinder. 2. A hydraulic shock absorber in which a bump stopper is held at the upper end of an outer cylinder whose upper end is crimped to regulate the mounting length at the time of contraction, and the lower surface of the disk-shaped bump stopper. Two large and small bowl-shaped protrusions are provided on the concentric circle, the large bowl secures a gap between the lower surface of the bump stopper and the crimped part at the upper end of the outer cylinder, and the small bowl electrically connects to the crimped part at the upper end of the outer cylinder. A bump stopper locking structure in a hydraulic shock absorber characterized by resistance welding. 3. An oil seal for slidably accommodating a piston rod assembly with a piston valve, a rod guide at an upper end, and a cylinder having a base valve at a lower end in an outer cylinder to shut off the outside air. In the hydraulic shock absorber in which the bump stopper is supported by electrical resistance welding on the crimped portion on the upper end of the outer cylinder that is sealed by crimping the upper end of the outer cylinder with the interposition of etc., the outside air is blocked above the rod guide. A hydraulic shock absorber in which an oil seal and a spacer for receiving a crimping load are superposed and interposed. 4. A hydraulic shock absorber in which a bump stopper is held at the upper end of an outer cylinder whose upper end is caulked and sealed so as to regulate the mounting length at the time of contraction, and the lower surface of the disk-shaped bump stopper. A bump stopper locking structure in a hydraulic shock absorber, characterized in that a protrusion is provided on a concentric circle, and a sharp end portion of the protrusion is electrically resistance welded to a caulking portion on an upper end of an outer cylinder.