JPH0979305A - Bump cushion of vehicle shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle bump cushion which produces little abnormal sound at compression, has a satisfactory resiliency, and can simply be molded. SOLUTION: In a bump cushion which has a rod insertion hole 11 formed going all the way through between both end, and has its one end taken as a fixed side 10a and has the other end taken as a cylinder facing side 10b facing a cylinder in a vehicle shock absorber, the inner peripheral surface 12b of the rod insertion hole on the cylinder facing side is shaped into such a slope that it expands toward one end face 14 on the cylinder facing side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bump cushion for a vehicle shock absorber.

[0002]

2. Description of the Related Art Conventionally, a shock absorber is used in a vehicle body of an automobile to absorb a shock or a vibration from a road surface, and a bump cushion is attached to a cylinder of the shock absorber. An example is shown in FIG.
In the figure, reference numeral 60 is a bump cushion, 70 is a shock absorber cylinder, 71 is a cylinder rod, and 74 is a coil spring. The bump cushion 60 is made of an elastic material such as rubber and has a tubular shape with a rod insertion hole 61 penetrating between both ends. The bump cushion 60 has the cylinder rod 7 in the rod insertion hole 61.
By inserting 1 into the shock absorber, it is attached between the cylinder 70 and the cushion guide 72 of the shock absorber.

One end of the bump cushion 60 is a fixed side 61a and the other end is a cylinder facing side 61b facing the cylinder of the shock absorber, and is fixed to the cushion guide 72 side. As shown in FIG. 6, the bump cushion 60 has a rod insertion hole 61, which is formed by annular recessed grooves 62, 64 formed on the inner peripheral surface of the rod insertion hole 61 on the substantially central portion 61c between both ends and the cylinder facing side 61b.
The inner peripheral surface has a bellows shape. Then, as shown in FIG. 7, when the cylinder 70 of the shock absorber moves forward (upward in the figure) due to impact or vibration from the road surface and its cap 73 collides with the lower end of the bump cushion 60, the bump cushion 60 Is compressed and deformed,
It exerts a high shock absorbing action by buffering the load from the shock absorber.

However, in the bump cushion 60 of this structure, the inner peripheral surface of the rod insertion hole 61 at the end of the cylinder facing side 61b is formed in the annular recessed groove 6 at that portion.
4, it is inclined toward the end face 63 of the cylinder facing side 61b so that the diameter becomes smaller. Therefore, as understood from FIG. 7, when the bump cushion 60 is compressed, the cylinder facing side 61 of the cylinder facing side 61b is compressed. The vicinity of the end face 63 is easily bent toward the cylinder rod 71 side. As a result, the end surface 63 on the cylinder facing side is liable to generate friction due to friction with the cap 73 of the cylinder.

Further, the bump cushion 60 is often formed by known injection molding, and when the molded bump cushion is released from the mold, as shown in FIG. so,
Using the elasticity of the material, it is pulled out from the inner diameter side mold 80. However, at that time, since the annular recessed grooves 62, 64 form an undercut shape and mesh with the outer surface of the inner diameter side mold 80, the bump cushion 60 may be cracked.

By the way, in order to eliminate the discomfort at the time of collision between the bump cushion 60 and the cylinder 70 of the shock absorber and improve the riding comfort, it is preferable to lower the spring elasticity of the bump cushion 60 at the initial stage of the collision. Moreover, the end surface 63 of the cylinder facing side 61b is
It is desirable to reduce the reaction force generated by the bending in the vicinity so that the relationship between the load and the deflection of the bump cushion 60 at the initial stage of the collision, that is, the spring characteristic becomes substantially linear. However, in the bump cushion 60 in which the annular recessed groove 64 is provided in the rod insertion hole 61 on the cylinder facing side 61b, the vicinity of the end face 63 may be caused due to a slight difference in the shape (dimension) or position of the annular recessed groove 64. The bending state of changes, and the reaction force generated thereby also changes. Moreover, the reaction force varies depending on the material of the bump cushion. Therefore, it is not easy to design the bump cushion so that the spring characteristics at the initial stage of the collision are linear.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve such a problem, and does not generate abnormal noise during compression, has a good spring elasticity, and is easy to mold. And it aims at providing the good bump cushion for vehicles.

[0008]

That is, the present invention provides:
In a bump cushion in which a rod insertion hole penetrating between both ends is formed, one end side being a fixed side and the other end side being a cylinder facing side facing a cylinder of a vehicle shock absorber, an inner peripheral surface of the rod inserting hole on the cylinder facing side To
The bump cushion of a vehicle shock absorber is characterized in that it has a sloped shape that widens toward the end surface on the cylinder facing side.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an example of a bump cushion of a vehicle shock absorber according to the present invention, FIG. 2 is a sectional view of an essential part showing a bump cushion immediately before a cylinder collides, and FIG. 3 is a sectional view showing its operation. 4 is a sectional view showing a state at the time of demolding.

As shown in FIGS. 1 and 2, the bump cushion 10 of the present invention is made of an elastic material such as rubber or urethane elastomer, and has a substantially cylindrical shape with a rod insertion hole 11 penetrating both ends thereof. Become. One end side is a fixed side 10a fixed to the vehicle body, and the other end side is a cylinder facing side 10 facing the cylinder of the shock absorber.
b. The outer peripheral surface 13 of the bump cushion 10 has a bellows shape, and one annular groove 15 corresponding to the bellows shape of the outer surface is formed on the inner peripheral surface of the rod insertion hole 11 at the substantially central portion.

The rod insertion hole 11 on the fixed side 10a has a smooth inner peripheral surface 12a and a diameter substantially equal to that of the cylinder rod 21, and is fitted into the cylinder rod 21 as shown in FIG. It is designed to be fixed.

On the other hand, the cylinder facing side 10b is the side on which the cylinder 20 of the shock absorber collides. The rod insertion hole 11 on the cylinder facing side 10b is an inclined surface that expands the inner peripheral surface 12b toward the cylinder facing side end surface 14 such that the diameter D1 on the tip side is larger than the inner diameter D2. It has a shape. In this embodiment, the inclined surface is slightly (several millimeters) inside the end surface 14 on the cylinder facing side, and the portion 16 near the end surface 14 is cylindrical. It should be noted that the vicinity of the end face may not be formed in a cylindrical shape but may be left in a sloped shape.

Since the inner peripheral surface 12b of the rod insertion hole on the cylinder-opposing side 10b is formed into a slanted surface that widens toward the end surface 14 on the cylinder-opposing side, as shown in FIG.
When the cylinder 20 collides with the end surface 14 of the bump cushion 10 together with the cap 22 and compresses the bump cushion 10, a force acting in the cylinder outer peripheral direction acts on the inclined surface portion. Further, the inner peripheral surface 12b of the rod insertion hole 11 on the cylinder facing side 10b is replaced with the end surface 1 on the cylinder facing side.
Since it has an inclined surface shape that widens toward 4, the inner peripheral surface 12b of the rod insertion hole 11 on the cylinder facing side 10b is
There is no annular groove for easily bending the end face 14 of the cylinder facing side 10b toward the cylinder rod 21.

These prevent the vicinity of the end face 14 of the cylinder facing side 10b from being bent toward the cylinder rod 21 at the time of the collision, and the unusual noise which is conventionally generated between the cylinder cap 22 and the cylinder cap 22 is less likely to occur. . Furthermore, since the vicinity of the end face 14 is not bent toward the cylinder rod 21, a reaction force due to the bending is not generated. Therefore, the spring characteristics at the initial stage of the collision can be made close to a straight line, and the riding comfort is improved.

The inclination θ of the inner peripheral surface 12b can be appropriately determined depending on the material of the elastic body forming the bump cushion 10 and the spring elasticity, and more specifically, about 5 ° to 30 °.
° is preferable.

If the inclination θ of the inner peripheral surface 12b is smaller than 5 °, the force applied to the cylinder facing side 10b during compression cannot be made constant in the cylinder outer peripheral direction, and the cylinder facing side 1
0b may bend to the cylinder rod 21 side,
Not only will the effect of preventing abnormal noise be uncertain, but the spring characteristics of the bump cushion will not be constant, and the durability of the bump cushion will also be affected. Also, 30 °
On the contrary, if it is larger than the above, on the contrary, the cylinder facing side 10b of the bump cushion 10 is likely to be bent in the cylinder outer peripheral direction, so that it is difficult to obtain desired spring elasticity, and the lower end of the bump cushion 10 and the cap 22 of the cylinder 20 are not easily obtained.
Friction occurs between the two and the abnormal noise cannot be completely prevented.

The bump cushion 10 of this embodiment is also used.
The outer peripheral surface 13a near the end surface 14 of the cylinder facing side 10b is inclined toward the end surface 14 so as to reduce the diameter. Therefore, due to the inclination of the outer peripheral surface 13a and the inclination of the inner peripheral surface 12b, the portion of the cylinder facing side 10b during the compression becomes more difficult to bend to either the cylinder rod 21 side or the cylinder 20 outer peripheral side. There is. The inclination α of the outer peripheral surface is preferably 30 ° to 70 ° when the inclination θ of the inner peripheral surface 12b is 5 ° to 30 °.

The bump cushion 10 can be molded by known injection molding as described above. However, the inner peripheral surface 12b of the rod insertion hole 11 on the cylinder facing side 10b is connected to the end surface 14 on the cylinder facing side 10b. Cylinder facing side 10
The inner peripheral surface 12b of b has no conventional annular groove, and the shape is simplified. Therefore, as shown in FIG. 4, it becomes easy to pull out the bump cushion 10 from the inner diameter mold 25, and at that time, it is possible to prevent the bump cushion from being broken or cracked.

[0019]

As shown and described above, according to the bump cushion of the vehicle shock absorber of the present invention, the inner peripheral surface of the rod insertion hole on the cylinder facing side expands toward the cylinder facing side end surface. Since it has a sloped shape, it is possible to prevent the vicinity of the end surface on the cylinder facing side from bending toward the cylinder rod side, and due to the bending, abnormal noise due to friction between the bump cushion end surface and the cylinder cap, which was conventionally caused. Can be reduced. Further, since the reaction force due to the bending of the end surface on the cylinder facing side toward the cylinder rod side does not occur, a feeling of strangeness when the bump cushion and the cylinder of the shock absorber come into contact with each other is not reduced, and riding comfort is improved.

Moreover, since the bump cushion of the vehicle shock absorber of the present invention has a simple shape of the inner peripheral surface of the rod insertion hole, it can be molded easily and satisfactorily, and cracks are not generated even when the mold is released. It does not break.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a bump cushion of a vehicle shock absorber according to the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a bump cushion immediately before a cylinder collides.

FIG. 3 is a cross-sectional view showing the operation thereof.

FIG. 4 is a cross-sectional view showing a demolded state during molding.

FIG. 5 is a cross-sectional view showing a state in which a general bump cushion is attached to a shock absorber.

FIG. 6 is a cross-sectional view showing an example of a bump cushion.

FIG. 7 is a sectional view showing the operation thereof.

FIG. 8 is a cross-sectional view showing a demolded state during molding.

[Explanation of symbols] 10 bump cushion 10a fixed side 10b cylinder facing side 11 rod insertion hole 12a fixed side inner peripheral surface 12b cylinder facing side inner peripheral surface 12 inner peripheral surface 13 outer peripheral surface 14 end surface 20 shock absorber cylinder 21 shock absorber Cylinder rod 22 Shock absorber cap

Claims (1)

[Claims] 1. A bump cushion in which a rod insertion hole penetrating between both ends is formed, one end side being a fixed side and the other end side being a cylinder facing side facing a cylinder of a vehicle shock absorber, the rod facing the cylinder. A bump cushion for a vehicle shock absorber, characterized in that an inner peripheral surface of the insertion hole has a sloped shape that widens toward an end surface on the cylinder facing side.