JP2004138134A - Bush structure - Google Patents

Abstract

Provided is a bush structure having a through hole that becomes a perfect circle after being restrained by a restraining member.
A bush structure having an insertion hole through which a stabilizer bar is inserted is restrained by a bracket having a U-shaped cross section, and is attached to a chassis component (such as a cross member) by a bolt. In order that the shape of the insertion hole 12b after the restraint by the bracket 14 becomes a perfect circle, the insertion hole 12a before the restraint is set such that the plane where the cross section of the insertion hole 12a by the virtual plane perpendicular to the restraint direction becomes the largest is the reference plane. The length (base length) R1 from the reference plane to the insertion hole 12a on the chassis component 16 side (base portion 13b side) is defined as the distance from the reference surface to the insertion hole 12a on the curved portion 13c side. A substantially elliptical shape longer than the length (bending portion side length) R2 is assumed to be in accordance with the restraining shape of the bracket 14.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bush structure for elastically attaching an insertion member to a base material, and is suitable for, for example, attaching a stabilizer bar to a chassis component (such as a cross member).
[0002]
[Prior art]
In order to elastically connect the components of the suspension and the vehicle body, bush structures are used in various parts. For example, when a stabilizer bar, which is a component of the suspension, is fixed to the body side of a chassis component (such as a cross member), a bush having the stabilizer bar inserted through the stabilizer bar insertion hole is fixed to the body side by a bracket. I do. FIG. 4 shows a conventional bush structure showing an example thereof.
[0003]
4A and 4B show a conventional bush structure, in which FIG. 4A is a side view of the bush in a no-load state, and FIG. 4B is a side view of the bush structure in a restrained state.
[0004]
As shown in FIG. 4, in the conventional bush structure, a bush 23 having an insertion hole 22 a through which a stabilizer bar is inserted is restrained by a bracket 24 having a substantially U-shaped cross section, and a bolt 25 Member 26). The bush 23 is provided with a cut 23a so that the stabilizer bar can be easily inserted, and the stabilizer bar is fitted into the insertion hole 22a from the cut 23a.
[0005]
In order to securely fix the bush 23 with the bracket 24, a fixing tightening allowance L is provided on the chassis component 26 side (the fixing (tightening) direction side of the bracket 24) of the bush 23. This is provided with a fixed tightening allowance L for the bush 23 on one of the three open surfaces of the bracket 24 in the tightening direction. When the bracket 24 is fixed, the bush 23 is restrained by the bracket 24, the bush 23 is pressed against the chassis component 26, and the fixing allowance L is compressed, so that the bush 23 is fixed to the bracket 24 ( Precompression in the direction of tightening). This pre-compression is generally performed and plays a role in preventing the bush 23 from falling off due to the operation of the stabilizer bar or the like.
[0006]
The bush 23 has an insertion hole 22a having a circular cross section in a no-load state regardless of its outer shape (see FIG. 4A). However, in the restrained state of the bush 23, the bush 23 is pre-compressed, so that the shape of the insertion hole 22a having the circular cross section is changed to the insertion hole 22b having the elliptical cross section compressed in the fixing (tightening) direction of the bracket 24. (See FIG. 4B). For this reason, the contact pressure between the stabilizer bar and the insertion hole 22b partially increases, and the abnormal noise generated during the operation of the stabilizer bar causes the abnormal noise to be transmitted from the stabilizer bar to the body side, and increases the friction of the suspension. It may be invited. This also contributes to poor ride quality. In FIG. 4, the center axis 21a of the stabilizer bar is also shown for comparison.
[0007]
As a technique for preventing the elliptical deformation of the bush insertion hole causing the above problem, the bush insertion hole is formed so that the bush insertion hole becomes circular when the bush is fixed to a bracket having a substantially U-shaped cross section. (Japanese Patent Application Laid-Open No. H11-163873) discloses a technique in which an elliptical shape is previously elongated in the bracket tightening direction.
[0008]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-177853 (pages 3-4, FIG. 1)
[0009]
[Problems to be solved by the invention]
In order for the insertion holes to provide the stabilizer bar with an appropriate contact pressure and hold the same, it is ideal that the surface pressure in the plane of the insertion hole contacting the stabilizer bar is uniform and uniform. For this purpose, it is preferable that the cross section of the stabilizer bar is a perfect circle, and the insertion hole for the stabilizer bar is a perfect circle slightly smaller than the cross section of the stabilizer bar.
[0010]
However, in the bush structure described in the above-mentioned Japanese Patent Application Laid-Open No. 9-177853, the bush has a shape having a curved portion corresponding to a U-shaped bracket (substantially semi-cylindrical shape). , The amount of deformation of the bush itself for the fixed tightening allowance is large in the tightening direction of the bush and small in the curved portion at the other end, and is not uniform. For this reason, also in the deformation of the insertion hole when the bush is fixed (at the time of restraint), the deformation amount of the insertion hole in the tightening direction side of the bush is large, and the deformation amount of the insertion hole in the curved portion side is small. Therefore, even if the insertion hole is previously formed in an elliptical shape that is long in the direction of tightening the bracket, it becomes a distorted circle after restraining the bush, and the stabilizer bar may not be held at a uniform surface pressure.
[0011]
In other words, if the shape of the insertion hole before restraint is not formed in consideration of the shape of the restraining member such as the bracket, the shape of the insertion hole may be simply an elliptical shape that is long in the tightening direction. Cannot be a perfect circle.
[0012]
The present invention has been made in view of the above problems, and has as its object to provide a bush structure having an insertion hole that becomes a perfect circle after being restrained by a restraining member.
[0013]
[Means for Solving the Problems]
The bush structure according to claim 1 of the present invention that solves the above-mentioned problem has a bush, which is restrained by a restraining member and is attached to the base material in a pre-compressed state, and the shape of the insertion hole after the restraint by the restraining member is a perfect circle. In this case, the shape of the restraining member has an insertion hole whose shape before restraint is optimized according to the shape of the restraining member.
[0014]
The bush structure according to claim 2 of the present invention that solves the above-mentioned problem has a configuration in which the restraining member that restrains the bush is U-shaped, and the bush is shaped to have a curved portion corresponding to the U-shaped restraining member. The plane from which the cross section of the insertion hole by the virtual plane perpendicular to the restraining direction that restrains the bush is the largest is defined as the reference plane, and the length from this reference plane to the insertion hole on the base material side is defined as the distance from this reference plane. A substantially elliptical insertion hole longer than the length of the insertion hole on the curved portion side is provided in the bush as the shape of the insertion hole before restraint.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
In FIG. 1, the deformation of the insertion hole of the bush will be described using a bush structure having a simple shape (a rectangular parallelepiped).
[0016]
1A and 1B show a bush structure having an oval insertion hole in a no-load state, wherein FIG. 1A is a side view of the bush in a no-load state, and FIG. 1B is a side view of the bush structure in a constrained state.
[0017]
The bush structure shown in FIG. 1 is substantially different from the bush structure shown in FIG. 4 except that the bush is a rectangular parallelepiped, the insertion hole is an ellipse long in the tightening direction, and the bracket has a U-shaped cross section. Absent. Therefore, a detailed description of this bush structure is omitted, and only the main points are described.
[0018]
When the side surface of the rectangular parallelepiped bush 3 is constrained by the bracket 4 having a U-shaped cross section, and the fastening allowance L for fixing the bush 3 is compressed and fixed to the chassis component (cross member or the like) 6, the bush 3 The deformation of the bush 3 in the direction perpendicular to the tightening direction is hardly restricted by the bracket 4, and the deformation mainly in the tightening direction (compression direction). Furthermore, since the cross-sectional area of the portion where the insertion hole 2a is provided is smaller than that of the other portions, the internal stress increases, and the deformation (compression) also increases. Therefore, in order for the insertion hole after restraint to become a perfect circle, the shape of the insertion hole in a no-load state needs to be an elliptical shape that is long in the compression direction.
[0019]
That is, in order to make the insertion hole described in Japanese Patent Application Laid-Open No. Hei 9-177853 into a perfect circle after restraining the bush, the insertion hole having an elliptical cross section long in the tightening direction is required to have a rectangular parallelepiped shape as shown in FIG. And a bush structure in which the rectangular parallelepiped bush is restrained in a pre-compressed state using a bracket having a U-shaped cross section.
[0020]
However, when the shape of the bracket is a U-shaped cross-sectional shape and the bush shape is a shape having a curved portion adapted to the bracket (kamaboko type), a simple elliptical insertion hole does not form a perfect circle. This is because, in a bush having a curved portion, the volume on the curved portion side of the bush is smaller than the volume on the non-curved portion side (base member side) of the bush. Is smaller on the curved portion side than on the non-curved portion side.
[0021]
In other words, the deformation amount on the non-bending portion side is larger than the deformation amount on the bending portion side, and most of the compression allowance due to the bush restraint is covered by the deformation amount on the non-bending portion side. The difference in the amount of deformation between the curved portion side and the non-curved portion side also appears. Therefore, the shape of the insertion hole needs to be an uneven ellipse having a longer radius at the non-curved portion side than at the curved portion side. FIG. 2 shows an example of such a bush structure.
[0022]
2A and 2B show a bush structure showing an example of an embodiment according to the present invention, wherein FIG. 2A shows a bush state in a no-load state, and FIG. 2B shows a bush state in a restrained state. In FIG. 2, for easy understanding, the bush has a shape formed of a rectangular parallelepiped and a semi-cylindrical curved portion, and the bracket has a U-shaped cross section corresponding to the bush. Also, the center of the semi-cylinder was made to be the center of the stabilizer bar.
[0023]
As shown in FIG. 2, in the bush structure according to the present invention, a bush 13 having an insertion hole 12 a through which a stabilizer bar is inserted is restrained by a bracket 14 having a U-shaped cross section, and a chassis component ( Cross member 16). The bracket 14 having a U-shaped cross section has a shape in which three surfaces in the inserting direction of the stabilizer bar and the tightening direction of the bush are opened. The bush 13 is provided with a cut 13a so that the stabilizer can be easily inserted, and the stabilizer is fitted into the insertion hole 12a from the cut 13a. In this embodiment, the cut 13a is provided at a position oblique to the tightening (fixing) direction of the bush 13. However, in order to prevent the cut 13a from shifting laterally, the bush 13 is tightened (fixed). It is better to provide it at a position perpendicular to the direction of ()).
[0024]
In order to securely fix the bush 13 with the bracket 14, a fixing tightening allowance L is provided on the chassis component 16 side (the fixing (tightening) direction side of the bracket 14) of the bush 13. When fixing the bracket 14, the bush 13 is restrained by the bracket 14, the bush 13 is pressed against the chassis component 16, and the fixing allowance L is compressed, thereby fixing the bush 13 to the bracket 14 (tightening). Attached) pre-compressed in the direction.
[0025]
In the bush structure according to the present invention, the shape of the insertion hole 12a before restraint is made to correspond to the restraint shape of the bracket 14 so that the shape of the insertion hole 12b after restraint by the bracket 14 becomes a perfect circle. Specifically, the shape of the insertion hole 12a before the restraint is substantially elliptical, and the plane where the cross section of the insertion hole 12a by the virtual plane perpendicular to the restraint direction for restraining the bush 13 is the largest is defined as a reference plane. The length from the reference plane to the insertion hole 12a on the chassis component 16 (base 13b) side (base length) R1 is the length from the reference plane to the insertion hole 12a on the curved portion 13c side ( (Bending portion side length) longer than R2. Further, the insertion hole 12a is set such that the size of the insertion hole 12b after restraint is smaller than the size of the stabilizer bar. For example, assuming that the radius of the insertion hole 12b after the constraint is R, a semi-ellipse on the chassis component 16 (base portion 13b) side having a short axis length R and a long axis length R1, and a short axis length R, A substantially elliptical insertion hole 12a is obtained by combining a semi-ellipse on the side of the curved portion 13c with the length R2 of the long axis.
[0026]
The insertion hole 12a may be provided shifted to the chassis component 16 (base portion 13b) side or the curved portion 13c side. In this case, a length (base portion side length) R1 from the center axis 11a of the stabilizer bar to the chassis component 16 side of the insertion hole 12a and a length (bending portion side length) R2 to the bending portion 13c side are represented by: Is changed in accordance with the volume ratio of the base 13b side and the curved portion 13c side of the bush 13 to the position of the insertion hole 12a. In other words, the length of the insertion hole 12a in the restricting direction of the bush 13 is determined based on the position of the insertion hole 12a as a reference and the volume in the restricting direction side and the volume in the opposite direction (in the present embodiment, the base portion 13b side). It is derived using the ratio of the volume (volume on the bending portion 13c side). As described above, in order to make the insertion hole 12b after restraint a perfect circle, the shape of the insertion hole 12a before restraint may be set according to the shape of the bracket 14 and the position of the insertion hole 12a in the bush 13.
[0027]
FIG. 3 shows an example in which the bush structure according to the present invention is used, and is a perspective view showing a suspension.
[0028]
As shown in FIG. 3, in the bush structure according to the present invention, in the suspension, the bush 13 having the insertion hole 12 through which the stabilizer bar 11 as the insertion member is inserted is restrained by the bracket 14 as the restraining member. In a pre-compressed state, it is attached to a chassis component (cross member or the like) 16 as a base material. The bush 13 is made of an elastic material such as rubber, and the elastic coefficient thereof is selected to be appropriate for holding the stabilizer bar 11.
[0029]
Due to the bush structure, the contact pressure between the stabilizer bar 11 and the insertion hole 12b can be made uniform over the entire inner surface thereof, preventing transmission of abnormal noise to the body side when the stabilizer bar 11 is operated, and friction of the suspension. Can be reduced. In addition, improvement in riding comfort can be expected due to the reduction in friction.
[0030]
【The invention's effect】
According to the first or second aspect of the present invention, the insertion hole of the bush attached to the base member is restrained by the restraining member, and the insertion hole of the bush attached to the base member becomes a perfect circle. Friction can be reduced.
[Brief description of the drawings]
FIG. 1 shows a bush structure having an elliptical insertion hole in a no-load state, where (a) is a side view of the bush in a no-load state and (b) is a side view of the bush structure in a constrained state.
FIGS. 2A and 2B are bush structures showing an example of an embodiment according to the present invention, wherein FIG. 2A is a side view of the bush in a no-load state, and FIG. 2B is a side view of the bush structure in a restrained state.
FIG. 3 is a perspective view showing a suspension using the bush structure according to the present invention.
4A and 4B show a conventional bush structure, in which FIG. 4A is a side view of the bush in a no-load state, and FIG. 4B is a side view of the bush structure in a restrained state.
[Explanation of symbols]
11a Stabilizer center shaft 12a Insertion hole (no load)
12b Insertion hole (restricted state)
13 Bush 13a Cut 13b Base 13c Curved portion 14 Bracket 15 Bolt 16 Chassis parts (cross member etc.)
L Tightening allowance for fixing R1 Base side length R2 Curved portion side length

Claims (2)

In a bush structure in which a bush having an insertion hole through which an insertion member is inserted is restrained by a restraining member and attached to the base material in a pre-compressed state,
A bush structure, wherein the shape of the insertion hole before restraint is made to correspond to the shape of the restraint member such that the shape of the insertion hole after restraint by the restraint member becomes a perfect circle. The bush structure according to claim 1,
The restraining member has a U-shaped shape, and the bush has a curved portion corresponding to the U-shaped restraining member,
The insertion hole before the restraint, the surface from which the cross section of the insertion hole by the virtual plane perpendicular to the restraint direction is the largest, as a reference surface, the length from the reference surface to the insertion hole on the substrate side from the reference surface. A bush structure having a substantially elliptical shape longer than a length from the reference plane to the insertion hole on the curved portion side.

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