Buffer stopper

Abstract

A buffer stopper having two-step characteristics is provided.　The buffer stopper comprises a ring-form elastic body 11 configured in a size that can be installed in an installation space, and an elastic body restraining member 21 that is placed so as to cover part of the outer peripheral portion of the elastic body 11 and that minimizes expansion of the elastic body 11. The elastic body 11 is provided between two members that are relatively displaced in the axial direction, and the elastic body has a first elastic body 12 that is axially compressed by the two members and to expand radially outward when the gap between the two members is reduced, and a second elastic body 13 configured to protrude outward from the outer peripheral surface of the first elastic body 12 at one end side of the first elastic body 12 in the axial direction. The elastic body restraining member 21 is configured so as to in cross section have an L shape covering the end surface on one end side of the elastic body 11 and the outer peripheral surface of the second elastic body 13, and the second elastic body 13 has, in an end surface on the side opposite from the one end side in the axial direction, a recess 14 that is recessed inward from the end surface.

Description

Technical Field

[0001] The present invention relates to a buffer stopper. More specifically, the present invention relates to a buffer stopper having a two-stage characteristic capable of switching from an initial characteristic to a secondary characteristic.

Background Art

[0002] In a steering system for an automobile or the like, in addition to the anti-vibration requirement such as the rattle sound of the worm gear portion, a rubber stopper may be used for the purpose of shock absorption (see, for example, Patent Document 1). For the target rubber stopper, as a required characteristic for absorbing shock while reducing noise and vibration, a two-stage characteristic in which the rigidity is low at the initial stage of load application and the rigidity becomes high when the stroke is equal to or more than a certain value is desirable. For example, as an existing technique, there is a technique of adjusting the restraint state of rubber and utilizing the volume compression of rubber in order to obtain a two-stage characteristic.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of using a conventional rubber stopper, it is necessary to bring the elastic body constituting the rubber stopper into contact with the outer wall of the counterpart (for example, a housing). Therefore, the conventional rubber stopper has a problem that it is difficult to satisfy the desired two-stage characteristic when the counterpart structure has no housing and is of a structure attached to an inner diameter shaft.

[0005] The present invention has been made in view of such a conventional technique. The present invention provides a buffer stopper having a two-stage characteristic capable of switching from an initial characteristic to a secondary characteristic.

Means for Solving the Problems

[0006] According to the present invention, there is provided a buffer stopper as described below.

[0007] [1] A ring-shaped elastic body configured to be sized to be attachable to an attachment space, and an elastic body restraint member disposed so as to cover a part of the outer peripheral portion of the elastic body and suppressing expansion of the elastic body. The elastic body is provided between two members that are relatively displaced in the axial direction, and includes a first elastic body that is axially compressed by the two members and expands radially outward when the interval between the two members is reduced, and a second elastic body configured to protrude outward from the outer peripheral surface of the first elastic body on one end side in the axial direction of the first elastic body. The elastic body restraint member covers the end surface on one end side of the elastic body and the outer peripheral surface of the second elastic body only and the height from the end face on the one end side coincides with the upper end of the second elastic body is configured in an L-shaped cross section. The second elastic body has a recess recessed inward from the end surface on the end surface on the side opposite to the one end side in the axial direction of the first elastic body, the buffer stopper.

[0008] [2] The buffer stopper according to [1], wherein the elastic body restraint member is made of a metal material or a hard resin material.

Advantages of the Invention

[0009] The buffer stopper includes an elastic body and an elastic body restraint member disposed so as to cover a part of the outer peripheral portion of the elastic body and suppressing expansion of the elastic body. The elastic body includes a first elastic body disposed between two members that are relatively displaced in the axial direction, and a second elastic body configured to protrude outward from the outer peripheral surface of the first elastic body. The second elastic body has a recess recessed inward from the end surface on the side opposite to the one end side in the axial direction covered by the elastic body restraint member.

[0010] The buffer stopper configured as described above has the effect of having a two-stage characteristic that can switch from an initial characteristic to a secondary characteristic. Specifically, when the elastic body is compressed by the input of a load, the first elastic body expands radially due to the compression. In the compression of the first elastic body in the initial stage, the elastic body has a relatively low rigidity. After passing through such an initial stage, when the first elastic body is further compressed and expands radially, along with the expansion, the concave portion of the second elastic body is filled by the elastic body, and the elastic body is constrained by the elastic body restraint member. In such a next stage, the elastic body becomes highly rigid and can generate a reaction force higher than that in the initial stage. Thus, the buffer stopper of the present invention can obtain an optimal two-stage characteristic in which the initial characteristic is low rigidity and becomes highly rigid with a certain stroke, which is an ideal characteristic for shock absorption.

[0011] Moreover, the buffer stopper of the present invention can set arbitrary two-stage characteristics regardless of the mating structure. Further, since no setting such as a housing is required for the mating structure, it is possible to save space at the site where the buffer stopper is provided.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and design changes, improvements, etc. can be appropriately made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0014] (1) Buffer stopper: The first embodiment of the buffer stopper of the present invention is a buffer stopper 10 as shown in FIGS. 1 to 3. The buffer stopper 10 of this embodiment includes a ring-shaped elastic body 11 configured to be sized to be attachable to the mounting space, and an elastic body restraint member 21 disposed so as to cover a part of the outer peripheral portion of the elastic body 11 and suppress the expansion of the elastic body 11. Here, FIG. 1 is a perspective view schematically showing the first embodiment of the buffer stopper. FIG. 2 is an enlarged cross-sectional view of a cross-sectional part of the buffer stopper shown in FIG. 1, and FIG. 3 is an enlarged cross-sectional view showing the deformed state of the buffer stopper shown in FIG. 2 when a load is applied.

[0015] The buffer stopper 10 of this embodiment can be used in places where shock absorption is required in vehicles such as automobiles, or in places where shock absorption is required in the construction field. For example, the buffer stopper 10 of this embodiment is mounted between the steering rack and the rack housing in the steering device of a vehicle such as an automobile, and when the steering device operates, it functions to stop the displacement of the steering rack while exerting a buffering action. Here, FIG. 4 is an explanatory diagram for explaining an example of an application location of the buffer stopper, and is a cross-sectional view schematically showing an example of the mounting state of the buffer stopper. In FIG. 4, reference numeral 30 indicates the buffer stopper. As shown in FIG. 4, the buffer stopper 30 is mounted on a worm 36 that constitutes a speed reduction mechanism or the like. The worm 36 is supported in a fitting hole of the housing 34 via bearings 32 as a pair of rolling bearings. By mounting the buffer stopper 30 in this way, when the steering device operates, the displacement of the steering rack can be stopped while exerting a buffering action.

[0016] The elastic body 11 includes a first elastic body 12 and a second elastic body 13 configured to protrude outward from the outer peripheral surface of the first elastic body 12 at one end side in the axial direction of the first elastic body 12. The first elastic body 12 is provided between two members that are relatively displaced in the axial direction, and when the distance between the two members is reduced, it is axially compressed by the two members and expands radially outward. On the other hand, the second elastic body 13 has a concave portion 14 that is recessed inward from the end surface on the side opposite to one end side in the axial direction.

[0017] The elastic body restraint member 21 is configured in an L-shaped cross-section that covers the end surface on one end side of the elastic body 11 and the outer peripheral surface of the second elastic body 13.

[0018] The buffer stopper 10 configured as described above has a two-stage characteristic that can be switched from an initial characteristic to a secondary characteristic. Specifically, for example, as shown in FIG. 2, when the elastic body 11 is compressed by an input load, the first elastic body 12 expands radially due to the compression. In such compression in the initial stage of the first elastic body 12, the elastic body 11 has a relatively low rigidity. After passing through such an initial stage, when the first elastic body 12 is further compressed and expands radially, along with the expansion, the concave portion 14 of the second elastic body 13 is filled by the deformed elastic body 11, and the elastic body 11 (particularly, the outer peripheral surface of the second elastic body 13) is restrained by the elastic body restraint member 21. In such a next stage, the elastic body 11 becomes highly rigid and can generate a reaction force higher than that in the initial stage. In this way, the buffer stopper 10 of the present embodiment can obtain an optimal two-stage characteristic in which the initial characteristic is low rigidity and the rigidity becomes high with a certain stroke, which is an ideal characteristic for shock absorption.

[0019] In addition, the buffer stopper 10 of the present embodiment can set arbitrary two-stage characteristics regardless of the counterpart structure. Furthermore, since no setting such as a housing is required for the counterpart structure, it is possible to save space at the site where the buffer stopper is provided.

[0020] As described above, the recess 14 formed in the second elastic body 13 is for filling at least a part of its internal space with the elastic body 11 as the first elastic body 12 expands, thereby generating a large reaction force on the elastic body 11. There are no particular restrictions on the capacity and size of the recess 14. For example, they can be appropriately adjusted in consideration of the magnitude of the load input to the elastic body 11 and the amount of change from the initial characteristics to the secondary characteristics of the elastic body 11. In FIG. 3, an example is shown where the entire internal space of the recess 14 in the second elastic body 13 is filled with the deformed elastic body 11. However, depending on the material constituting the elastic body 11, the capacity of the recess 14, etc., in the next stage after the above-described initial stage, a part of the internal space of the recess 14 in the second elastic body 13 may be configured to be filled with the deformed elastic body 11. However, in order to effectively exhibit the two-stage characteristics as described above, it is more preferable that the internal space of the recess 14 in the second elastic body 13 is configured to be completely filled as the first elastic body 12 expands. Therefore, an appropriate volume of the recess 14 can be determined from the deformation amounts of the rubber materials of the first elastic body 12 and the second elastic body 13 constituting the elastic body 11.

[0021] The elastic body 11 is preferably a rubber elastic body made of a rubber material. There are no particular restrictions on the type of rubber material, and it can be appropriately determined according to the use and use environment of the buffer stopper 10. For example, the rubber material to be used as the elastic body 11 can be selected in consideration of the temperature when the buffer stopper 10 is used and whether the use environment is an oil-scattered environment or not. Although not particularly limited, since oil resistance is often required in the use environment of the buffer stopper 10, rubber materials generally excellent in oil resistance, such as acrylic rubber (ACM) materials and hydrogenated nitrile rubber (HNBR) materials, can be cited as preferred examples of the rubber material to be used as the elastic body 11.

[0022] The elastic body restraint member 21 is for suppressing the expansion of the elastic body 11, and is formed of a material having a higher rigidity than the elastic body 11. The elastic body restraint member 21 is preferably made of a metal material or a hard resin material. By using the elastic body restraint member 21 made of a metal material or a hard resin material, high durability against the input of an impact load (rubber compression deformation) can be obtained.

[0023] Hereinafter, the operation and effect of the buffer stopper 10 of the present embodiment will be described in more detail with reference to the graph shown in FIG. 5. Here, FIG. 5 is a graph showing the relationship between the reaction force [N] and the displacement [mm] in the buffer stopper 10 of the present embodiment. In the graph shown in FIG. 5, the vertical axis represents the load [N] input to the elastic body, and the horizontal axis represents the displacement [mm] of the elastic body. Also, "without L-shaped member" indicated by the dashed-dotted line in FIG. 5 shows the relationship between the load [N] and the displacement [mm] of the buffer stopper manufactured without providing the elastic body restraint member 21 in the buffer stopper 10 as shown in FIGS. 1 to 3. "With L-shaped member (analysis)" indicated by the dotted line in FIG. 5 shows the result of analyzing the relationship between the load [N] and the displacement [mm] of the buffer stopper 10 as shown in FIGS. 1 to 3. "With L-shaped member (measured)" indicated by the solid line in FIG. 5 shows the measurement result of the relationship between the load [N] and the displacement [mm] of the buffer stopper 10 as shown in FIGS. 1 to 3. The graphs showing the analysis and measurement shown in FIG. 5 are based on the result of displacing the elastic body 11 in the load direction with respect to the buffer stopper 10 having the shape shown in FIG. 2 and analyzing or measuring the reaction force.

[0024] The three graphs shown in Fig. 5 all show a tendency that the displacement [mm] of the elastic body increases as the load [N] input to the elastic body increases. However, for the graphs of "with L-shaped member (analysis)" and "with L-shaped member (actual measurement)", up to around 100 N of load, the slopes of the respective graphs are relatively gentle, indicating that the elastic body in the buffer stopper has low rigidity characteristics. And from around when the load exceeds 100 N, the slope of the graph gradually becomes steeper, and the graph rises sharply around 200 - 300 N of load. The range where the slope around 100 N of load gradually becomes steeper mainly corresponds to the range during the displacement period until the concave portion of the second elastic body is filled by the deformed elastic body. And the range where the graph rises even more sharply mainly corresponds to the range where the filling of the concave portion of the second elastic body is completed, the radial expansion of the second elastic body progresses, and the outer peripheral surface of the second elastic body is restrained by the elastic body restraint member (L-shaped member). In such a range, the elastic body becomes highly rigid and generates a higher reaction force than in the initial stage.

Industrial Applicability

[0025] The buffer stopper of the present invention can be used for locations where impact absorption is required in vehicles such as automobiles, or in the construction field and other locations where impact absorption is required.

Explanation of Reference Numerals

[0026] 10: Buffer stopper 11: Elastic body 12: First elastic body 13: Second elastic body 14: Concave portion 21: Elastic body restraint member 30: Buffer stopper 32: Bearing 34: Housing 36: Worm

Claims

1. A ring-shaped elastic body configured to be sized to be mounted in a mounting space, and an elastic body restraint member disposed so as to cover a part of the outer peripheral portion of the elastic body and suppressing expansion of the elastic body. The elastic body is provided between two members that are relatively displaced in the axial direction, and is a first elastic body that is axially compressed by the two members and expands radially outward when the distance between the two members is reduced, and a second elastic body configured to project outward from the outer peripheral surface of the first elastic body at one end side in the axial direction of the first elastic body. The elastic body restraint member covers only the end face on the one end side of the elastic body and the outer peripheral surface of the second elastic body, and is configured in a cross-sectional L shape in which the height from the end face on the one end side coincides with the upper end of the second elastic body. The second elastic body is a buffer stopper having a recess recessed inward from the end face on the end side opposite to the one end side in the axial direction.

2. The buffer stopper according to claim 1, wherein the elastic body restraint member is made of a metal material or a hard resin material.

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