Bush and suspension arm

Abstract

The present invention inhibits a bush comprising no outer cylinder from slidingly rotating with respect to a link member.　This bush 1 comprises an inner cylinder 2 and an elastic body 3 provided to the outer periphery of the inner cylinder 2 and is press-fitted to a link member 4, wherein: the elastic body 3 has a base part 31 and a plurality of projection parts 32 that project outward from the base part 31; and each of the plurality of projection parts 32 is configured such that the compression ratio Cr thereof when press-fitted to the link member 4 is greater than the compression ratio Cr1 of the base part 31 (Cr > Cr1).

Description

Bushings and Suspension Arms

[0001] The present invention relates to a bushing and a suspension arm.

[0002] Bushes used in vehicle suspension arms and the like are generally constructed by placing an elastic body such as rubber between an inner tube and an outer tube, but from the perspective of reducing costs and weight, there are also so-called outerless bushes in which the outer tube is removed and the elastic body is compressed and pressed into the link member (for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 11-117974

[0004] However, in the case of an outerless bushing such as that described in Patent Document 1, when the displacement in the torsional direction becomes large, the frictional force of the elastic body against the link member (specifically, the force that presses the elastic body against the inner surface of the link member and secures it to the link member) becomes insufficient, causing slippage and rotation of the entire bushing.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to suppress sliding rotation of a bushing that does not have an outer cylinder relative to a link member.

[0006] In order to achieve the above object, the present invention provides a bushing that includes an inner tube and an elastic body provided on the outer periphery of the inner tube and is press-fitted into a link member, wherein the elastic body has a base and a plurality of protrusions that protrude outward from the base, and each of the plurality of protrusions has a compression rate when pressed into the link member that is set to be greater than the compression rate of the base.

[0007] In addition, in order to achieve the above-mentioned object, the suspension arm of the present invention comprises a bush having the above-mentioned characteristics and a link member having at one end an inner surface corresponding to the outer shape of the bush, and the bush is pressed into the link member with the elastic body compressed without leaving a gap between the bush and the inner surface of the link member.

[0008] According to the present invention, it is possible to suppress the sliding rotation of the bushing that does not have an outer cylinder relative to the link member. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiment.

[0009] FIG. 1 is an external side view showing the appearance of a bushing according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view showing an example of the configuration of a suspension arm provided with the bushing shown in FIGS. 1 to 3. FIG. 5 is a diagram showing an example of the configuration of a suspension arm according to a comparative example. FIG. 6 is a cross-sectional view showing an example of the configuration of a bushing according to modified example 2. FIG. 7 is a cross-sectional view showing an example of the configuration of a suspension arm provided with the bushing shown in FIG.

[0010] Hereinafter, as one aspect of a bush and a suspension arm according to an embodiment of the present invention, a bush and a suspension arm for a vehicle used in a vehicle suspension or the like will be described as an example.

[0011] <Configuration of Bush 1> First, the configuration of the bush 1 will be described with reference to FIGS.

[0012] Fig. 1 is a side view showing the appearance of a bushing 1 according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1.

[0013] The bushing 1 is an outerless bushing that does not have an outer cylinder, and includes an inner cylinder 2 formed from a cylindrical metal member, and an elastic body 3 provided on the outer periphery of the inner cylinder 2. Note that the inner cylinder 2 does not necessarily have to be cylindrical, and may be, for example, a rectangular cylinder. The bushing 1 is attached to a link member 4 of a vehicle suspension, and the bushing 1 and the link member 4 together form a suspension arm 5 (see FIG. 4).

[0014] The hollow portion of the inner tube 2 forms a bolt hole 20 through which a bolt is inserted. The bolt is inserted from one end of the bolt hole 20 and fastened to a nut located on the other end. In this way, the bushing 1 is attached to a member to be fastened. The member to be fastened is, for example, a bracket on the vehicle body side or a bracket on the tire side.

[0015] The elastic body 3 is made of, for example, a rubber material, and absorbs vibrations generated in the fastened members and the link member 4 (see FIG. 4). Note that the elastic body 3 does not necessarily have to be made of a rubber material, and can be made of any material that can absorb vibrations.

[0016] 3, the elastic body 3 has a base 31 oriented along the outer peripheral surface of the inner cylinder 2, and a plurality of (six in this embodiment) protrusions 32 protruding outward from the base 31. The base 31 and the plurality of protrusions 32 are integrally molded, and the surface portion is smoothly continuous in an arc shape.

[0017] In this embodiment, the multiple protrusions 32 are each formed to have the same length W from the outer periphery of the inner tube 2 to the protruding end, and are arranged at equal intervals along the circumferential direction of the inner tube 2. In other words, the elastic body 3 according to this embodiment has an outer shape in which the corners of a regular hexagon protrude uniformly outward.

[0018] The plurality of protrusions 32 do not necessarily have to be formed with the same length W, and may protrude unevenly. The intervals between adjacent protrusions 32 do not necessarily have to be the same, and may be different.

[0019] <Configuration of Suspension Arm 5> Next, the configuration of the suspension arm 5 will be described with reference to FIGS. 4 and 5. FIG.

[0020] Fig. 4 is a cross-sectional view showing an example of the configuration of a suspension arm 5 provided with the bushing 1 shown in Figs. 1 to 3. Fig. 5 is a diagram showing an example of the configuration of a suspension arm 500 according to a comparative example.

[0021] 4, the suspension arm 5 includes the bushing 1 and a link member 4. The link member 4 is formed of a metal member such as iron, and has an elongated cylindrical arm portion 41 and a press-fit portion 42 provided at one end of the arm portion 41 and into which the bushing 1 is press-fitted.

[0022] The press-fitted portion 42 has an inner surface 420 (in this embodiment, a regular hexagonal shape) that corresponds to the outer shape of the bushing 1. The bushing 1 is press-fitted into the press-fitted portion 42 with no gap between it and the inner surface 420 and the elastic body 3 compressed.

[0023] At this time, the compression rate Cr of each of the plurality of protruding portions 32 of the bushing 1 is greater than the compression rate Cr1 of the base portion 31 (Cr>Cr1). Specifically, it is desirable that the compression rate Cr of each of the plurality of protruding portions 32 when press-fitted into the press-fitted portion 42 is set to be two to four times the compression rate Cr1 of the base portion 31 (Cr=2 to 4×Cr1).

[0024] Here, the sliding rotation of the bushing 1 relative to the link member 4 will be described using a comparative example shown in Fig. 5. In Fig. 5, components that are common to components according to this embodiment are denoted by the same reference numerals.

[0025] The bushing 100 according to the comparative example does not have multiple protrusions, and an elastic body 300 formed in a regular hexagonal shape is provided on the outer periphery of the inner cylinder 2. If the rubber material characteristics of the elastic body 300 are qualitatively uniform, the apex portion, which is thicker than the main body portion, will have lower rigidity (thickness L2 of the apex portion > thickness L1 of the main body portion).

[0026] This tendency is thought to remain unchanged even after the link member 4 is pressed into the press-fit portion 42, so even in the elastic body 300 pressed into the press-fit portion 42, the apex portion has lower rigidity than the main body portion.

[0027] For a suspension arm 500 equipped with such a bush 100 and a link member 4, when a load is applied to the link member 4 in the axial direction (specifically, from the other end of the arm portion 41 toward the pressed-in portion 42), the displacement of the apex portion of the elastic body 300 increases, and since the main body portion has high rigidity, the reaction force that the inner tube 2 receives from the main body portion increases.

[0028] 5, the bushing 100 shifts toward the apex where the inner cylinder 2 has a smaller reaction force, changing the direction of displacement and reducing rigidity, causing the bushing 100 to slip relative to the link member 4. Generally, when an input is applied to the link member 4, that is, when a load is applied in the axial direction, a torsional displacement also occurs in the bushing 100.

[0029] Therefore, even when the bush 100 is displaced with an axial load applied to the link member 4, it is required that the reaction force received by the inner tube 2 from the apex portion and the reaction force received from the main body portion are equal, or that the reaction force received from the apex portion is greater than the reaction force received from the main body portion.

[0030] In this regard, the bushing 1 according to this embodiment is provided with a plurality of protrusions 32 whose low-rigidity apex portions protrude outward, and the reaction force that the inner cylinder 2 receives from the plurality of protrusions 32 is greater than the reaction force that the inner cylinder 2 receives from the base 31. As a result, the bushing 1 is more suppressed from sliding and rotating relative to the link member 4 than the bushing 100 according to the comparative example.

[0031] If the rubber thickness of the multiple protrusions 32 (corresponding to the length W shown in FIG. 3) is twice the rubber thickness of the base 31 and the rigidity of the multiple protrusions 32 is half (1 / 2) of the rigidity of the base 31, the compression ratio of the multiple protrusions 32 will be the same as that of the base 31. However, since the rigidity of the multiple protrusions 32 is lower than that of the base 31, the generated stress will be lower than the stress of the base 31, resulting in bias.

[0032] Therefore, it is desirable to set the compression rate Cr of the multiple protrusions 32 so that the stress generated in the multiple protrusions 32 exceeds the stress in the base 31, even if the displacement amount of the bush 1 becomes the maximum value of the displacement amount of the bush 1 that is normally expected.

[0033] The relationship between the compression rate Cr of the multiple protrusions 32 and the compression rate Cr1 of the base 31 varies depending on the shape of the bushing 1 after it is pressed into the link member 4 and the direction in which the load acts on the link member 4 (including input in the prying direction), but it is desirable that the compression rate Cr of the multiple protrusions 32 be two to four times the compression rate Cr1 of the base 31.

[0034] Next, a bushing and a suspension arm according to a modified example of the present invention will be described with reference to Figures 6 to 9. Note that components in the modified example that are common to those described in the above embodiment will be assigned the same reference numerals, and descriptions thereof will be omitted.

[0035] Fig. 6 is a cross-sectional view showing an example of the configuration of a bushing 1A according to Modification 1. Fig. 7 is a cross-sectional view showing an example of the configuration of a suspension arm 5A provided with the bushing 1A shown in Fig. 6.

[0036] In the bushing 1A according to the first modification, the elastic body 3A has four protrusions 32. As in the embodiment, each of the four protrusions 32 has the same length W from the inner cylinder 2 to its protruding end, and is arranged at equal intervals along the circumferential direction of the inner cylinder 2. In other words, the outer shape of the elastic body 3A is a square with corners that protrude uniformly outward.

[0037] 7, the press-fitted portion 42A of the link member 4 has a square inner surface 420A corresponding to the outer shape of the bushing 1A. The bushing 1A is press-fitted into the press-fitted portion 42A with the elastic body 3A compressed, without leaving a gap between the bushing 1A and the inner surface 420A of the press-fitted portion 42A. In the first modification, the compression rate Cr of each of the four protrusions 32 when press-fitted into the link member 4 is set to be greater than the compression rate Cr1 of the base portion 31 (Cr>Cr1).

[0038] As a result, the bushing 1A and the suspension arm 5A according to the first modification also achieve the same functions and effects as the bushing 1 and the suspension arm 5 according to the first embodiment. As such, there is no particular limit to the number of the plurality of protrusions 32.

[0039] Fig. 8 is a cross-sectional view showing an example of the configuration of a bushing 1B according to Modification 2. Fig. 9 is a cross-sectional view showing an example of the configuration of a suspension arm 5B provided with the bushing 1B shown in Fig. 8 .

[0040] In the bushing 1B according to the second modification, the elastic body 3B has six protrusions 32B, similar to the bushing 1 according to the first embodiment. However, as shown in Fig. 9 , unlike the six protrusions 32 according to the first embodiment, the six protrusions 32B are not arranged at equal intervals along the circumferential direction of the inner cylinder 2, but are arranged in groups of three, symmetrically positioned about the axis of the link member 4B.

[0041] In Modification 2, the link member 4B has an arm portion and a press-fit portion molded integrally, and one end has an inner surface 420B that corresponds to the outer shape of the bushing 1B. The bushing 1B is press-fitted into the link member 4B with the elastic body 3B compressed, without leaving a gap between the bushing 1B and the inner surface 420B. In Modification 2, the compression rate Cr of each of the six protrusions 32B when press-fitted into the link member 4 is set to be greater than the compression rate Cr1 of the base 31 (Cr>Cr1).

[0042] As a result, the bushing 1B and the suspension arm 5B according to the second modification also achieve the same functions and effects as the bushing 1 and the suspension arm 5 according to the first embodiment. As such, the multiple protrusions do not necessarily need to be arranged at equal intervals along the circumferential direction of the inner cylinder 2.

[0043] The above describes the embodiments and modifications of the present invention. Note that the present invention is not limited to the above-described embodiments and modifications, and various other modifications are also included. For example, the above-described embodiments and modifications have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of this embodiment and modifications with configurations of other embodiments, and it is also possible to add configurations of other embodiments to the configuration of this embodiment and modifications. Furthermore, it is possible to add, delete, or replace part of the configuration of this embodiment and modifications with other configurations.

[0044] 1, 1A, 1B: bushing 2: inner cylinder 3, 3A, 3B: elastic body 4, 4B: link member 31: base 32, 32B: protrusion 420, 420A, 420B: inner surface Cr, Cr1: compression ratio W: length

Claims

1. A bushing comprising an inner tube and an elastic body provided on the outer periphery of the inner tube, the bushing being press-fitted into a link member, wherein the elastic body has a base and a plurality of protrusions protruding outward from the base, and the compression rate of each of the plurality of protrusions when press-fitted into the link member is set to be greater than the compression rate of the base.

2. A bushing as claimed in claim 1, characterized in that the plurality of protrusions are arranged in a line at equal intervals along the circumferential direction of the inner cylinder.

3. A bushing as claimed in claim 1, wherein each of the plurality of protrusions is formed to have the same length from the outer periphery of the inner cylinder to the protruding end.

4. A bushing as claimed in claim 1, characterized in that the compression rate of each of said plurality of protrusions when press-fitted into said link member is set to be two to four times the compression rate of said base.

5. A suspension arm comprising the bushing according to any one of claims 1 to 4, and a link member having at one end an inner surface corresponding to the outer shape of said bushing, wherein said bushing is press-fitted into said link member with said elastic body compressed, without leaving any gap between said bushing and said inner surface of said link member.

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