Bushing

Abstract

The purpose of the present invention is to provide a bushing capable of suppressing the influence on the ratio between the spring characteristics in the solid direction orthogonal to the axis and the spring characteristics in the hollow direction orthogonal to the axis, and also capable of suppressing displacement in the solid direction orthogonal to the axis. This bushing is provided with: an inner cylinder; an outer cylinder; and an elastic body disposed between the inner tube and the outer tube, the elastic body having a hollow portion penetrating in the axial direction, the inner tube having a protruding portion protruding in the hollow direction orthogonal to the axis, the protruding portion protruding further outward in the hollow direction orthogonal to the axis than the innermost point of the hollow portion in the hollow direction orthogonal to the axis, and the protruding portion protruding further outward in the hollow direction orthogonal to the axis than the innermost point of the hollow portion in the hollow direction orthogonal to the axis. At least a portion of the protrusion is adjacent to the elastic body.

Description

Technical Field

[0001] The present invention relates to bushings, and more particularly to trailing arm bushings for vehicles. Background Art

[0002] Bushings are used in vehicles to reduce vibration. These bushings include an outer cylinder, an inner cylinder, and an elastic body disposed between the outer and inner cylinders (see, for example, Patent Document 1). Such bushings require the elastic body to be durable. However, because the elastic body is subjected to not only torsional input (input in the rotational direction about the axis) but also large input in a direction perpendicular to the axis, ensuring the durability of the elastic body is difficult.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-204339. Summary of the Invention

[0006] Problems to be solved by the invention

[0007] For large inputs in the solid direction perpendicular to the axis (where the entire area perpendicular to the axis is composed of an elastic body), displacement can be suppressed by providing a protrusion (e.g., made of metal) extending outward from the inner cylinder in the solid direction perpendicular to the axis. However, as vehicle performance becomes more sophisticated, bushings used in vehicles are also required to exhibit the desired spring characteristics in each direction. This countermeasure has the following problem: the ratio of the spring characteristics in the solid direction perpendicular to the axis to the spring characteristics in the hollow direction perpendicular to the axis (where a hollow portion is provided in a partial area perpendicular to the axis) (spring characteristics in the solid direction perpendicular to the axis / spring characteristics in the hollow direction perpendicular to the axis) changes (increases).

[0008] Therefore, an object of the present invention is to provide a bushing capable of suppressing the influence on the ratio of the spring characteristic in the axially perpendicular solid direction to the spring characteristic in the axially perpendicular hollow direction, and suppressing the displacement in the axially perpendicular solid direction.

[0009] Solutions for solving problems

[0010] The main structure of the present invention is as follows.

[0011] (1) A bushing, characterized in that it comprises: an inner tube; an outer tube; and an elastic body, which is arranged between the inner tube and the outer tube, the elastic body having a hollow portion extending in the axial direction, the inner tube having a convex portion protruding in the axially perpendicular hollow direction, the convex portion protruding to the outside of the axially perpendicular hollow direction compared to the innermost point of the hollow portion in the axially perpendicular hollow direction, and at least a portion of the convex portion is adjacent to the elastic body.

[0012] (2) The bushing according to the above (1) is characterized in that the convex portion has a shape in which the width gradually increases from the inside toward the outside in the axially perpendicular hollow direction.

[0013] (3) The bushing according to (1) or (2) above is characterized in that a plate is arranged between the outer tube and the hollow portion in the axially perpendicular direction to the hollow portion.

[0014] Effects of the Invention

[0015] According to the present invention, a bushing can be provided that can suppress the influence on the ratio of the spring characteristic in the axially perpendicular solid direction to the spring characteristic in the axially perpendicular hollow direction and suppress the displacement in the axially perpendicular solid direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is an end view showing a bushing according to one embodiment of the present invention from the axial direction.

[0017] Figure 2 yes Figure 1 sectional view of .

[0018] Figure 3 yes Figure 1 Another cross-sectional view of .

[0019] Figure 4 This is an end view showing a bushing according to another embodiment of the present invention as viewed from the axial direction.

[0020] Figure 5 yes Figure 4 sectional view of .

[0021] Figure 6 It is a diagram showing an application example of the bushing.

[0022] Figure 7 This is an end view showing a bushing of a comparative example from the axial direction.

[0023] Figure 8 This is a graph showing the evaluation results of Example 2. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0025] Figure 1 This is an end view showing a bushing according to one embodiment of the present invention from the axial direction. Figure 2 yes Figure 1 sectional view of . Figure 3 yes Figure 1 In this specification, the direction perpendicular to the axial direction of the bushing is referred to as the "axis-perpendicular direction."

[0026] like Figures 1 to 3 As shown, the bushing 1 of this embodiment includes an inner tube 2 , an outer tube 3 , and an elastic body 4 disposed between the inner tube 2 and the outer tube 3 .

[0027] In this embodiment, the inner cylinder 2 and the outer cylinder 3 are arranged concentrically around the axis O when viewed in a cross-section perpendicular to the axial direction. In this embodiment, the inner cylinder 2 is made of metal. Specifically, the inner cylinder 2 can be made of carbon steel, an aluminum alloy, or the like. In this embodiment, the outer cylinder 3 is made of metal. Specifically, the outer cylinder 3 can be made of carbon steel, an aluminum alloy, or the like.

[0028] In this embodiment, the elastic body 4 is made of rubber. However, the elastic body 4 can also be formed of an elastic material other than rubber. The elastic body 4 elastically connects the inner tube 2 and the outer tube 3.

[0029] In this embodiment, a hollow portion (gap) 5 extending axially through the elastic body 4 is formed. In this example, the hollow portion 5 is provided at two locations in the vertical direction shown in the figure, one located above the inner tube 2 and one located below the inner tube 2.

[0030] In the example shown, the hollow portion 5 is composed of a slit portion 5a extending in a wave-like manner in a generally circumferential direction, and hole portions 5b extending from both ends of the slit portion 5a to both sides in a generally axially perpendicular direction. The wave-like extension of the slit portion 5a can suppress the generation of abnormal noise when the slit portion 5a is collapsed and abuts against the protrusion 2a.

[0031] In the bushing 1 of this embodiment, the inner tube 2 has a convex portion 2a that protrudes in the axially perpendicular hollow direction. In this example, the inner tube 2 has two convex portions 2a: a convex portion 2a that protrudes toward the upper side as shown in the figure, and a convex portion 2a that protrudes toward the lower side as shown in the figure. In the example shown in the figure, the convex portion 2a has a shape in which the width gradually increases from the inner side (the center axis О side) toward the outer side in the axially perpendicular hollow direction. In the bushing 1 of this embodiment, the convex portion 2a protrudes outward in the axially perpendicular hollow direction relative to the innermost point of the hollow portion 5 in the axially perpendicular hollow direction (in this example, the innermost point of the hole portion 5b in the axially perpendicular hollow direction). Moreover, at least a portion of the convex portion 2a (in the example shown in the figure, a portion within the circled area A) is adjacent to the elastomer 4. In this example, at least a portion of the protrusion 2a (in the example shown in the figure, a portion within the area A surrounded by a circle) is in contact with the elastomer 4, but on the other hand, at least a portion of the protrusion 2a may not be in contact with the elastomer 4, but may be adjacent to it to the extent that it can be in contact during use.

[0032] Hereinafter, the effects of the bushing 1 according to the present embodiment will be described.

[0033] In the bushing 1 of this embodiment, the inner tube 2 has a protrusion 2a that projects in the axially perpendicular hollow direction. At least a portion of the protrusion 2a (in the illustrated example, a portion within the circled region A) abuts the elastic body 4. Therefore, even when a large input is applied in the axially perpendicular solid direction, displacement of at least a portion of the protrusion 2a compresses and deforms the elastic body 4 through the contact area with the elastic body 4, thereby mitigating the input and suppressing displacement in the axially perpendicular solid direction. Furthermore, since the protrusion 2a projects outward from the innermost point of the hollow portion 5 in the axially perpendicular hollow direction, a sufficient protrusion width is ensured, effectively achieving the aforementioned effect. Furthermore, since this method requires little modification to the shape of the elastic body 4, the effect on the ratio of the spring characteristics in the axially perpendicular solid direction to the spring characteristics in the axially perpendicular hollow direction can be minimized. Furthermore, the timing of suppressing displacement in the axially perpendicular solid direction can be adjusted by designing the shape of the protrusion 2a.

[0034] Furthermore, as in this embodiment, by having the convex portion 2a having a shape with a width gradually increasing from the inside toward the outside in the axially perpendicular hollow direction, it is possible to advance the timing at which the convex portion 2a is displaced and the elastic body 4 is compressed and deformed when a large input is generated in the axially perpendicular solid direction. Figure 4 As shown, the convex portion 2a can also have a shape with a substantially constant width from the inside to the outside in the axially perpendicular hollow direction, or can have other various shapes, thereby adjusting the timing of suppressing displacement in the axially perpendicular solid direction.

[0035] like Figure 4 、 Figure 5 As shown, it is also preferred to configure a plate 6 between the outer cylinder 3 and the hollow portion 5 in the direction perpendicular to the axis. This is because the impact of input in the direction perpendicular to the axis can be reduced, and the occurrence of metal-to-metal noise caused by wear of the elastic body can be prevented. The plate 6 is preferably made of metal such as steel. In addition, this is because it allows for the freedom of design of the inner cylinder 2 and the elastic body 4. In addition, Figures 1 to 3 In the bushing 1 of the illustrated embodiment, the plate 6 can also be arranged between the outer tube 3 and the hollow portion 5 in the axially perpendicular direction to the hollow portion.

[0036] Figure 6 FIG is a diagram showing an application example of a bushing. Figure 6 As shown, the bushing 1 of each embodiment described above can be applied to a suspension device 10. The suspension device 10 includes a pair of left and right trailing arms 11 on which tires are mounted, a torsion bar 12 connecting the pair of left and right trailing arms 11, and a bushing 1 connecting the trailing arms 11 to a vehicle body.

[0037] While the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

[0038] Example

[0039] (Example 1)

[0040] In order to clarify the effect of the present invention, FEM analysis simulation was performed. Figure 4 、 Figure 5 As shown in FIG, the inner tube has a convex portion, and a plate is arranged between the outer tube and the hollow portion. Figures 1 to 3 As shown, the inner tube has a convex portion, and the convex portion has a shape in which the width gradually increases from the inside toward the outside in the direction perpendicular to the hollow of the axis. In Example 2 of the invention, no plate is configured. The comparative example is set as follows Figure 7 As shown, the inner tube does not have a convex portion, and a plate is arranged between the outer tube and the hollow portion.

[0041] FEM analysis was used to simulate deformation when loads were applied in various directions. As shown in Table 1 below, in Inventive Examples 1 and 2, deformation in the direction perpendicular to the axis was significantly reduced compared to the Comparative Example. Table 1 shows the values as indices, with the Comparative Example result set to 100. Lower values indicate lower deformation.

[0042] [Table 1]

[0043]

[0044] (Example 2)

[0045] Next, bushings corresponding to the comparative example of Example 1, Inventive Example 1, and Inventive Example 2 were trial-produced respectively, and the deflection and durability when a load was applied in the solid direction orthogonal to the shaft were evaluated. The evaluation was carried out according to the following steps. (i) First, before the endurance test, the spring characteristics in each direction were measured (in Table 2, in the item "Spring before endurance test", when the spring before endurance test of the comparative example is set to 100, the spring before endurance test of Inventive Examples 1 and 2 at this time is represented by an index, and the larger the value, the larger the spring before endurance test). (ii) Next, a specified number of vibrations were applied under specified load conditions, and after the specified number of vibrations were applied, the spring characteristics in each direction were measured again. Then, the spring change rate before and after the endurance test was calculated (in Table 2, it was expressed as "Spring change improvement index after endurance", expressed as an index when the comparative example is set to 1, and the larger the value, the more improved the characteristics). Among them, in the comparative example, the elastic body was severely damaged and the test was interrupted. In the inventive example 1, since cracks occurred in the elastic body during the application of vibration, the vibration was stopped midway, and the spring characteristic of applying vibration until the midway number was adopted. Figure 8 The evaluation results are shown in Table 2.

[0046] [Table 2]

[0047]

[0048] like Figure 8 As shown in Table 2, the effects on the ratio of the spring characteristics in the solid direction perpendicular to the axis to the spring characteristics in the hollow direction perpendicular to the axis are suppressed in Inventive Examples 1 and 2, compared to the Comparative Example. Furthermore, as shown in Table 2, the effects on the ratio of the spring characteristics in the solid direction perpendicular to the axis to the spring characteristics in the hollow direction perpendicular to the axis are suppressed in Inventive Examples 1 and 2, and the durability of the bushing is improved compared to the Comparative Example.

[0049] Description of Reference Numerals

[0050] 1: Bushing; 2: Inner tube; 3: Outer tube; 4: Elastic body; 5: Hollow part; 6: Plate; 10: Suspension device; 11: Trailing arm; 12: Torsion bar.

Claims

1. A bushing, characterized in that: It has: an inner tube; an outer tube; and an elastic body, which is arranged between the inner tube and the outer tube, The elastic body has a hollow portion penetrating in the axial direction, The inner cylinder has a convex portion protruding in the direction perpendicular to the hollow of the axis. The convex portion protrudes outward in the direction perpendicular to the hollow portion relative to the innermost point of the hollow portion. At least a portion of the protrusion is adjacent to the elastic body.

2. The bushing according to claim 1, wherein: The convex portion has a shape in which the width gradually increases from the inside toward the outside in the axially perpendicular hollow direction.

3. The bushing according to claim 1, wherein: A plate is arranged between the outer cylinder and the hollow portion in a direction perpendicular to the hollow portion.

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