JP2003184938A - Bump stopper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bump stopper, having excellent durability to withstand repeated loads imposed by great compressive loads. <P>SOLUTION: In the bump stopper 20, a fit part 21 formed in the upper inside peripheral face is fit to a piston rod 12 with an appropriate interference, an upper end 20a is brought into contact with the lower internal periphery of a spring-retainer 13, and a lower end 20b is faced to an upper end face 11a of a cylinder 11 in a shock absorber 10. The bump stopper 20 is molded cylindrically of a rubbery elastic material. An annular recess 22 is formed on the outside periphery continuously in the peripheral direction. The outside peripheral face constituting the upper side of the recess 22 and lower than the outside peripheral face is formed with a relatively small diameter. A lower-side internal face 22b of the recess 22 is formed to have a rounded face in a clad shape higher than a virtual tapered face 22b' symmetric with respect to an upper inside face 22a. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bump stopper provided on an automobile suspension.

[0002]

2. Description of the Related Art Between a vehicle body and a wheel side of an automobile,
A suspension device and a shock absorber are provided, and vibrations and impacts transmitted from the road surface during traveling are absorbed and attenuated by the suspension device and the shock absorber. A bump stopper made of a rubber-like elastic material is attached to the piston rod of the shock absorber.

FIG. 4 is a sectional view of a bump stopper according to the prior art in a mounted state. Reference numeral 101 in the drawing is a shock absorber cylinder, and 102 is a piston rod (strad rod) projecting axially upward from the cylinder 101. 103 are spring receiving plates fixed to the upper end of the piston rod 102 and supporting the upper end of a suspension spring (not shown).

The bump stopper 110 is formed of a rubber-like elastic material such as urethane, and has an outer annular concave portion 111 and an inner annular concave portion 112 which are circumferentially continuous on the outer peripheral surface and the inner peripheral surface and alternate in the axial direction. The outer peripheral surface is formed into a bellows shape having a gradually decreasing diameter toward the lower side, is fitted on the piston rod 102, and the fitting portion 113 formed on the upper inner peripheral surface is suitable for the piston rod 102. It is fitted with an interference. In addition, the bump stopper 11
The upper end 110a of 0 is in contact with the spring receiving plate 103, and the lower end 110b, which is a free end, faces the upper end surface 101a of the cylinder 101.

In the above-mentioned structure, the shock absorber cylinder 10 is input by the input of shock vibration while the vehicle is running.
When the piston rod 102 is relatively retracted into the cylinder 101 while the suspension spring is being compressed, the lower end 110b of the bump stopper 110 causes the lower end 110b of the bump stopper 110 to move toward the upper end surface 101a of the cylinder 101. The bump stopper 110,
Each outer annular recess 111 and each inner annular recess 112 undergo axial compressive deformation so as to bend. Therefore, the bump stopper 110 exerts a buffering effect by the cooperation of the compression of the suspension spring and the operation of the internal mechanism of the shock absorber.

[0006]

However, the bump stopper 110 according to the prior art has the annular recesses 11 in each.
When the inner surfaces of 1,112 were subjected to such a large amount of compression that they were in pressure contact with each other, cracks C were sometimes generated in the outer diameter portion. This is because the inner surface of each outer annular recess 111 is a tapered surface 111a, 111b having a linear cross section, and the outer peripheral surface 114 of the bump stopper 110 is relatively below the upper side of each outer annular recess 111. Because of the small diameter, the tapered surfaces 111a, 111b of the outer annular recess 111 are
It is assumed that the lower edge-shaped shoulder portion 111c is in pressure contact with the upper tapered surface 111a when they are pressed against each other, and stress is likely to be concentrated in that portion.

The present invention has been made in view of the above problems, and a technical object thereof is to provide a bump stopper excellent in durability against repeated load due to a large compressive load.

[0008]

The conventional technical problems can be effectively solved by the present invention. That is, the bump stopper according to the invention of claim 1 is formed into a tubular shape from a rubber-like elastic material, and has an annular concave portion which is continuous in the circumferential direction on the outer peripheral surface, and which is lower than the outer peripheral surface above the annular concave portion. In a bump stopper having a relatively small outer peripheral surface, the lower inner surface of the annular recess forms a rounded surface with a higher build-up than the symmetrical surface with the upper inner surface of the annular recess. It is a thing.

The bump stopper according to the invention of claim 2 is
An annular ring fitting recess is formed on the outer peripheral surface of the rubber-like elastic material to fit the restraint ring, and an annular recess that is adjacent to the upper side of the ring fitting recess and is continuous in the circumferential direction is formed. In the bump stopper in which the outer peripheral surface below the annular recess is smaller in diameter than the outer peripheral surface above the annular recess, the lower inner surface of the annular recess is a symmetry plane with the upper inner surface of the annular recess. The upper surface of the restraint ring is positioned lower than the lower inner surface.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a bump stopper according to the present invention in a mounted state showing a first preferred embodiment. In FIG. 1, reference numeral 10 is a shock absorber provided in a suspension of an automobile, and includes a cylinder 11 in which a piston having an orifice is incorporated and oil is enclosed, and a cylinder 11 extending from the piston.
1 has a piston rod (strad rod) 12 projecting axially upward from the upper end axial hole of 1, and kinetic energy is attenuated by the viscosity of the oil that operates with the movement of the piston. A spring receiving plate 13 made of a metal plate that supports the upper end of a suspension spring (not shown) is fixed to the upper end of the piston rod 12.

Reference numeral 20 is a bump stopper externally fitted to the piston rod 12. This bump stopper 2
In No. 0, in the fitting portion 21 formed on the upper inner peripheral surface, the outer peripheral surface of the piston rod 12 is fitted with an appropriate tightening margin, and the upper end portion 20a contacts the inner peripheral surface of the lower surface of the spring receiving plate 13. The lower end portion 20b is in contact with the upper end surface 11a of the cylinder 11 of the shock absorber 10.

The bump stopper 20 is formed in a tubular shape from a rubber-like elastic material such as urethane foam, and has a plurality of circumferentially continuous steps (three steps in the illustrated example) on its outer peripheral surface. An outer annular recess 22 is formed. Further, the inner peripheral surface 20c has a larger diameter than the piston rod 12 below the fitting portion 21 with the piston rod 12, and the inner peripheral surface 20c has a plurality of circumferentially continuous steps ( In the illustrated example, three stages of inner annular recessed portions 23 are formed. The outer annular recesses 22 and the inner annular recesses 23 are located alternately in the axial direction, so that the bump stopper 20 has a bellows shape. Further, the outer peripheral surface of the bump stopper 20 is formed so as to have a relatively small diameter below the upper side of each outer annular recess 22. Therefore, the outer diameter gradually decreases downward and becomes thin. There is.

The outer annular recesses 22 have a larger radial undulation than the inner annular recesses 23, and the inner surfaces 22 of the outer annular recesses 22 facing each other vertically.
The inner surfaces 22a and 22b of the upper side (hereinafter referred to as the upper inner surface) 22a have a tapered shape in which the diameter gradually increases toward the upper side, whereas the inner surface of the lower side (hereinafter referred to as the lower inner surface) 22b. However, it is an R surface having a built-up shape higher than a virtual taper surface (taper surface 22b 'shown by a broken line in the figure) symmetrical to the upper inner surface 22a. Further, the smallest diameter portion of each outer annular recess 22, that is, the bottom portion 22c, forms an R-shaped concave surface.

In the bump stopper 20 according to the first embodiment having the above-mentioned structure, the cylinder 11 of the shock absorber 10 is abruptly displaced upward from the state shown in the figure by the impact vibration input while the vehicle is traveling. When the piston rod 12 of the shock absorber 10 is relatively retracted into the cylinder 11 while the suspension spring is being compressed, the bump stopper 2
The lower end portion 20b of 0 abuts on the upper end surface 11a of the cylinder 11, and is compressed and deformed in the axial direction (vertical direction) so as to be bent between the spring receiving plate 13 and the outer annular concave portions 22 and the inner annular concave portions 23. By receiving it, it exerts a buffering effect. And this bump stopper 20 is
Since the thickness is thinner toward the bottom, the amount of deformation gradually increases from the bottom, and thus the spring constant is non-linear in the process of being compressed until the inner surfaces 22a and 22b of the outer annular recesses 22 come into pressure contact with each other. To limit the stroke of the piston rod 12.

Since the outer peripheral surface located on the lower side when viewed from each outer annular recess 22 has a smaller diameter than the outer peripheral surface located on the upper side, the lower inner surface 22b of the outer annular recess 22 is the upper inner surface 22a. It will be pressed against the middle abdomen. Figure 2
It is sectional drawing which shows this press contact state partially. That is,
As described above, the lower inner surface 22 of the outer annular recess 22 is
Since b has a built-up R surface, it is pressed against the upper inner surface 22a at the R surface as shown in FIG. 2, and stress concentration is suppressed. For this reason, even if it receives repeated pressure contact by compression, the upper inner surface 22a is less likely to crack, and the durability is improved.

When a durability test in which a load of 9 kN was repeatedly applied was applied, the bump stopper 110 of the conventional structure shown in FIG. 4 cracked about 10,000 times, whereas the crack of FIG. In the bump stopper 20 according to the embodiment, no crack was observed until the number of compressions reached 100,000.

Next, FIG. 3 is a sectional view of a mounted state showing a second preferred embodiment of the bump stopper according to the present invention. In FIG. 3, reference numeral 10 is a shock absorber, which is the same as that in FIG. 1 described above, and the bump stopper 20 according to the present embodiment is formed in a tubular shape from a rubber-like elastic material such as urethane foam. In the fitting portion 21 formed on the inner peripheral surface of the upper portion, the piston rod 1
2 and the upper end 2
0a is in contact with the inner peripheral surface of the lower surface of the spring receiving plate 13, and the lower end portion 20b is opposed to the upper end surface 11a of the cylinder 11 of the shock absorber 10.

On the outer peripheral surface of the bump stopper 20, a plurality of steps (three steps in the illustrated example) of outer annular recesses 22A to 22C, which are continuous in the circumferential direction, an outermost annular recess 22C at the lowermost side, and an outer outer ring in the middle are provided. A ring fitting concave portion 24 is formed between the concave portions 22B and is continuous in the circumferential direction. Further, the inner peripheral surface 20c has a larger diameter than the piston rod 12 below the fitting portion 21 with the piston rod 12, and the inner peripheral surface 20c has a plurality of circumferentially continuous steps ( In the illustrated example, four stages of inner annular recessed portions 23 are formed.
The outer annular recesses 22A to 22C, the ring fitting recesses 24, and the inner annular recesses 23 are located alternately in the axial direction. Therefore, the bump stopper 20 has a bellows shape.
Further, the outer peripheral surface of the bump stopper 20 is formed to have a relatively small diameter below the upper side of each of the outer annular recesses 22A to 22C, so that the outer diameter gradually decreases downward and becomes thin. Has become.

A restraint ring 30 is provided in the ring fitting recess 24.
Are mounted in a fitted state. This restraint ring 30
For example, it is formed of 66 nylon mixed with about 30% of glass fiber, and the inner peripheral surface 31 has a taper shape that becomes thicker toward the inner diameter side toward the lower side and near the lower end thereof. The smallest diameter portion 32 has an R surface. The inclination angle of the inner peripheral surface 31 with respect to the virtual cylindrical surface centering on the axis is 15 to 30 °, preferably 17 to 20 °. The ring fitting recess 24 is also formed in a cross-sectional shape corresponding to the inner peripheral surface 31 and the minimum diameter portion 32 of the restraint ring 30.

The outer annular recesses 22A to 22C have a larger radial undulation than the inner annular recesses 23, and the upper and lower parts of the intermediate outer annular recess 22B adjacent to the upper side of the ring fitting recess 24 are vertically adjacent to each other. Inner surface 22 facing the
The inner surfaces 22a and 22b of the upper side (hereinafter referred to as the upper inner surface) 22a have a tapered shape in which the diameter gradually increases toward the upper side, whereas the inner surface of the lower side (hereinafter referred to as the lower inner surface) 22b. Is an R surface having a built-up shape higher than a virtual taper surface (taper surface 22b 'shown by a broken line in the figure) symmetrical to the upper inner surface 22a, and the minimum diameter portion, that is, the bottom portion 22c is an R-shaped concave surface. Is doing. The upper end surface 30a of the restraint ring 30 is located below the lower inner surface 22b of the intermediate outer annular recess 22B.

The uppermost outer annular recessed portion 22A and the lowermost outer annular recessed portion 22C are tapered so that the upper inner surface 22d thereof gradually increases in diameter toward the upper side, and the lower inner surface 2
2e has a tapered surface that is symmetrical with the upper inner surface 22d, that is, a taper shape that gradually increases in diameter downward, and the bottom portion 22f has an R-shaped concave surface.

As with the first embodiment, the bump stopper 20 according to the second embodiment having the above-described structure also causes the cylinder 11 of the shock absorber 10 to move upward from the state shown by the impact vibration input while the vehicle is running. When the piston rod 12 is relatively retracted into the cylinder 11 while the suspension spring is compressed, the lower end portion 20b of the bump stopper 20 comes into contact with the upper end surface 11a of the cylinder 11 in the process. The bump stopper 20 undergoes compressive deformation in the axial direction (vertical direction) with the spring receiving plate 13. Since the bump stopper 20 is thinner toward the lower side, the deformation amount increases from the lower side, and thus the inner surfaces of the outer annular recesses 22A to 22C are compressed until they come into pressure contact with each other. Thus, the spring constant increases non-linearly, limiting the stroke of the piston rod 12.

Here, the restraint ring 30 is deformed such that the taper angle of the inner peripheral surface 31 is changed due to the deformation of the ring fitting recess 24 due to the compression of the bump stopper 20, and the ring is thus deformed. Since the fitting force with the fitting recess 24 is increased, the ring fitting recess 24 does not fall off and is firmly held. The restraint ring 30 maintains good non-linear load-deflection characteristics of the bump stopper 20 even under a high load and suppresses bulging deformation toward the outer peripheral side at the time of compression, and therefore durability against repeated compression deformation. Can be increased.

Here, the bump stopper 20 has a high rigidity because the portion where the ring fitting concave portion 24 is formed can be restrained from bulging and deforming toward the outer peripheral side at the time of compression by the restraining ring 30, that is, Intermediate outer annular recess 22
Although the lower portion of B has a high rigidity, the lower inner surface 22b of the outer annular recess 22B has a built-up R surface, so that the upper inner surface 22 as shown in FIG.
The R surface is pressed against a and pressure concentration is suppressed. Further, since the upper end surface 30a of the restraint ring 30 is below the built-up lower inner surface 22b, the restraint ring 3
0 does not press-contact the upper inner surface 22a of the outer annular recess 22B. For this reason, even if it receives repeated pressure contact by compression, cracks are unlikely to occur on the upper inner surface 22a, and durability is improved.

In the example shown in FIG. 3, the intermediate outer annular recess 22B adjacent to the upper side of the restraint ring 30 is formed.
Only the lower inner surface 22b has a built-up R surface shape, but the other outer annular recesses 22A and 22C similarly have the lower inner surface 22b.
You may make e be a buildup shape.

[0026]

According to the bump stopper of the first aspect of the present invention, the lower inner surface of the annular recess formed continuously on the outer peripheral surface in the circumferential direction is thicker than the symmetrical surface with the upper inner surface. Since the R-shaped surface has a curved shape, even if the inner surfaces of the outer annular recesses are subjected to a large compression such that they are in pressure contact with each other, the stress concentration due to pressure contact is suppressed, so that cracks on the upper inner surface are less likely to occur and repeated loading It is possible to provide a bump stopper excellent in durability against.

According to the bump stopper of the second aspect of the present invention, the restraint ring maintains good non-linear load-deflection characteristics of the bump stopper even at high loads.
Demonstrate excellent performance. Moreover, since the lower inner surface of the annular recess located directly above the bump stopper mounting portion forms an R surface that is more padded than the symmetrical surface with the upper inner surface, the rigidity is increased by the bump stopper. Concentration of stress when the side inner surface is brought into pressure contact with the upper inner surface is suppressed, so that cracks on the upper inner surface are less likely to occur, and a bump stopper excellent in durability against repeated loads can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a mounted state showing a first preferred embodiment of a bump stopper according to the present invention.

FIG. 2 is an enlarged cross-sectional view partially showing a pressed state of the bump stopper of FIG.

FIG. 3 is a sectional view of a mounted state showing a second preferred embodiment of the bump stopper according to the present invention.

FIG. 4 is a sectional view of a mounted state showing a bump stopper according to a conventional technique.

[Explanation of symbols]

10 shock absorber 11 cylinders 12 piston rod 13 Spring support plate 20 bump stopper 21 Fitting part 22, 22A to 22C Outer annular recess (annular recess) 22a Upper inner surface 22b lower inner surface 22b 'An imaginary taper surface symmetrical with the upper inner surface 23 Inner annular recess 24 Ring fitting recess 30 restraint ring 30a upper end surface 31 inner surface 32 smallest diameter

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Claims (2)

[Claims] 1. A rubber-like elastic material is formed into a tubular shape, and an annular concave portion (22) is formed on an outer peripheral surface thereof and is continuous in a circumferential direction.
In the bump stopper (20) in which the outer peripheral surface below the annular recess (22) is formed to have a relatively smaller diameter than the outer peripheral surface above the annular recess (22), the lower inner surface (22b) of the annular recess (22) is , A bump stopper characterized in that it forms an R surface having a built-up shape higher than a virtual surface (22b ') symmetrical to the upper inner surface (22a). 2. An annular ring fitting recess (24) which is formed into a tubular shape from a rubber-like elastic material and which fits a restraining ring (30) on an outer peripheral surface, and an upper side of the ring fitting recess (24). A bump stopper (22B) is formed adjacent to each other in the circumferential direction, and the outer peripheral surface below the outer peripheral surface above the annular recess (22B) has a relatively small diameter. 20), the lower inner surface (22b) of the annular recess (22B) is higher than the virtual inner surface (22b ') symmetrical to the upper inner surface (22b), and has a shape R
A top surface (30a) of the restraining ring (30)
Is located below the lower inner surface (22b).