JP5140484B2 - Elastic bush - Google Patents

Description

  The present invention includes an outer cylinder and a cylindrical elastic body bonded to the inner peripheral surface of the outer cylinder by vulcanization adhesion, adhesive bonding, or the like. Sometimes, the outer cylinder is bonded to the inner peripheral surface of the elastic body. It is related to an elastic bush that may have a rigid inner cylinder. For example, the outer cylinder shrinks into a sleeve attached to the rear suspension arm, trailing arm, torque rod or other arm member of an automobile. Effectively eliminates variation in dimensions after press-fitting when press-fitting at the bottom, and breakage of the outward flange located at the rear end in the press-fitting direction of the outer cylinder that is brought into surface contact with the end face of the sleeve by the press-fitting The technology to be removed is proposed.

  Various types of elastic bushes and vibration-proof devices using the elastic bushes have been proposed. One example is disclosed in Patent Document 1.

This is a cylindrical rigid sleeve under the reduced diameter deformation of an outer cylinder, which is made of a bushing having an outer cylinder made of resin for the purpose of weight reduction, an inner cylinder, and a rubber elastic body disposed therebetween. In the cylindrical vibration isolator constructed by press-fitting into the sleeve, a concave portion is formed on the inner surface of the sleeve so that the inner surface has a stepped shape, while the outer surface of the outer tube is substantially straight in the axial direction. A stepped shape in which the outer cylinder is pressed into the sleeve while reducing the diameter of the outer cylinder using the elastic deformation of the resin, and the outer shape of the outer cylinder is imitated with the inner shape of the sleeve by the elastic restoring force after the press fitting. None, the stepped portion of the sleeve and the stepped portion of the outer cylinder are engaged with each other in the axial direction and in the pulling direction, and this is still good when the outer cylinder of the elastic bush is made of resin. It is assumed that it can be prevented from coming off.
JP 2004-176803 A

  By the way, in this prior art, as illustrated in FIG. 3, the outer cylinder 52 of the elastic bush 51 is formed at the rear end in the press-fitting direction to the sleeve 53, and the sleeve 53 is in a press-fitting completion posture to the sleeve 53. Since the outward flange 54 in surface contact with the end surface is formed to project radially outward in a plane orthogonal to the central axis line cl of the elastic bush 51, the elastic bush 51 is deformed by reducing the diameter of the outer cylinder 52. As shown in FIG. 3B, when the cylindrical portion 55 of the outer cylinder 52 is deformed to be reduced in diameter by the rigid sleeve 53 under the restriction by the inner diameter in press fitting into the sleeve 53 below. The outward flange 54 gradually falls and deforms toward the sleeve 53 side as it approaches the sleeve 53, while the elastic bush 51 is completely press-fitted into the sleeve 53. Under condition, the outward flange 54, under abutment against the end face of the sleeve 53, as shown in FIG. 3 (a), so that the original upright position is deformed pushed back.

  As described above, in this prior art, the outward flange 54 of the outer cylinder 52 is greatly collapsed and deformed toward the sleeve 53 side during the press-fitting of the elastic bush 51 into the sleeve 53, while at the end of the press-fitting, the outward flange 54. After contact with the end surface of the sleeve 53, it is pushed back in the direction opposite to the direction of the fall, and particularly large strain and stress are generated in the protruding base portion of the outward flange 54 at the time of this pushing back deformation. Therefore, when the outer cylinder 52 is made of resin, the protruding base portion of the outward flange 54 is likely to be damaged, such as cracks. There was a problem of being broken.

On the other hand, when the outer cylinder 52 is made of metal, it is necessary to push back and deform the outward flange 54, which has fallen into the sleeve 53 and deformed in the reverse direction, with its plastic deformation. An increase in the press-fit resistance of the elastic bush 51 due to the deformation resistance of the outward flange 54 cannot be denied. Therefore, when press-fit with a predetermined force is performed, variation in assembly dimensions after press-fit is likely to occur. There was a problem in dimensional accuracy.
The same thing may occur when the outer cylinder 52 is made of resin.

  SUMMARY OF THE INVENTION An object of the present invention is to solve such problems of the prior art, and the object of the present invention is to effectively prevent the occurrence of damage to the outward flange and to provide an elastic bushing. It is an object of the present invention to provide an elastic bushing that can sufficiently eliminate variations in assembly dimensions.

  The elastic bushing of the present invention comprises an outer cylinder and a cylindrical elastic body, for example, a rubber elastic body, which is joined to the inner peripheral surface of the outer cylinder by vulcanization adhesion, adhesive adhesion, or the like. Furthermore, a high-rigidity inner cylinder joined to the inner peripheral surface may be provided. For example, the outer cylinder is inserted into a rigid sleeve attached to the rear suspension arm, trailing arm, torque rod, or other arm member of an automobile. It is press-fitted under reduced diameter deformation, and is used for use in a state where the outer peripheral surface of the cylindrical portion of the outer cylinder is frictionally engaged with the inner peripheral surface of the rigid sleeve. The contact surface with the sleeve of the outward flange that is located at the surface and is in surface contact with the end surface of the rigid sleeve is an inclined surface that faces radially outward.

Wherein the inclined surface, in cross-section in comprising a central axis, the curve which is convex towards the outside or the inside in the radial direction, it is possible to a rotating body shape about its central axis, the In the invention , at least the peripheral portion of the contact surface with the sleeve of the outward flange is a frustoconical surface.
In this case, the entire flange inclined surface can be a frustoconical surface, but the remaining portion of the inclined surface excluding the peripheral portion can be a convex curved surface or a concave curved surface.

However, the frusto-conical surface as described above, the inclination angle with respect to a plane perpendicular to the central axis shall be the range of 1 to 30 °.
This also applies to the case where the inclined surface is a combination of a truncated conical surface and another curved surface.
In this case, the inclination angle of the portion other than the truncated conical surface can be obtained as the inclination angle of the tangent line drawn to the midpoint in the cross section including the central axis.

Incidentally, the contact surface between the sleeve of the outward flange, in the section including the center axis, if it smoothly made continuous via a curved into the cylindrical portion of the outer tube, due to the deformation of the outward flange, the projecting Concentration of stress and strain on the base can be prevented, and these are particularly preferable when the outer cylinder is made of resin.

  In particular, the elastic bushing of the present invention has an outer flange located on the rear end in the press-fitting direction, and has an inclined surface that faces the sleeve in the radially outward direction. When press-fitting into the sleeve under the reduced diameter deformation of the cylinder, it is assumed that the outward flange itself collapses into the sleeve side by the same amount as that of the prior art as in the prior art shown in FIG. However, before press-fitting, the sleeve contact surface of the outward flange, which consists of an inclined surface facing outward in the radial direction, does not collapse as much as shown in the figure, and within the cross section including the central axis, Therefore, at the end of press-fitting of the elastic bushing, the sleeve contact surface is deformed in the pushing-back direction by contact with the end surface of the sleeve, and finally, In addition, it is possible to effectively reduce the required amount of pushing back deformation of the sleeve contact surface as compared with the prior art even when the push back posture is orthogonal to the central axis under surface contact with the end surface of the sleeve. it can.

  Therefore, even when the outer cylinder is made of resin, the strain and stress generated at the protruding base of the flange can be effectively relieved based on the reduction of the amount of push-back deformation of the sleeve contact surface of the outward flange compared to the prior art. Thus, it is possible to effectively prevent the occurrence of damage such as cracks and breaks on the protruding base portion of the outward flange.

On the other hand, when the outer cylinder is made of metal, the deformation resistance of the flange is reduced on the basis of the reduction in the required amount of push-back deformation accompanying the plastic deformation of the flange of the sleeve contact surface of the outward flange that has fallen and deformed. Due to this, it is possible to advantageously reduce the press-fitting resistance of the elastic bushing to the sleeve, so that even if the elastic bushing is press-fitted under force management, the assembly size of the elastic bushing to the sleeve Can be effectively removed.
This also applies to the case where the outer cylinder is made of resin.

  Here, when the contact surface of the outward flange with the sleeve is a frustoconical surface at least in the periphery thereof, the elastic bushing is made of resin regardless of whether it is made of resin or metal. Under the posture where the press-fitting into the sleeve is completed, at least the peripheral portion of the sleeve contact surface can be sufficiently brought into close contact with the sleeve end surface, and the generation of a gap between them can be effectively prevented.

Note here, when the outer cylinder is made of resin, the contact surface with the sleeves of the outward flange, with or without a truncated conical surface as described above, a convex or concave radially outwardly curved As yet, under the flexibility inherent to the outward flange, as the press-fit of the elastic bushing into the sleeve is completed, its sleeve contact surface should be sufficiently tightly adhered to the sleeve end surface throughout it. Can do.

  By the way, when at least a part of the contact surface with the sleeve of the outward flange is a frustoconical surface, when the inclination angle of the frustoconical surface with respect to the surface orthogonal to the central axis is in the range of 1 to 30 ° In addition, it is possible to more effectively prevent damage to the projecting base portion of the outward flange, and it is possible to more advantageously eliminate variations in the assembly dimensions.

That is, if the inclination angle is less than 1 °, it is not effective to make the contact surface with the sleeve an inclined surface facing radially outward. On the other hand, if the inclination angle exceeds 30 °, the press-fit of the elastic bush is completed. The contact surface cannot be brought into close contact with the end surface of the sleeve, resulting in an appearance problem that a gap remains between them.
This also applies to the case where the inclined surface facing outward in the radial direction is a combination of a truncated conical surface and another curved surface.
Here, the inclination angle of the portion other than the truncated conical surface can be obtained as an intersection angle between the tangent drawn to the midpoint in the cross section including the central axis and the orthogonal surface.

  The same applies to the inclination angle of the inclined surface that does not include the frustoconical surface at all, and can be obtained as the angle of intersection between the tangent drawn to the midpoint in the cross section including the central axis and the orthogonal surface.

  Also, here, when the contact surface with the sleeve of the outward flange is smoothly connected to the cylindrical portion of the outer cylinder through a curve within the cross section including the central axis, the contact surface with the sleeve of the outward flange When the contact surface is deformed in the pushing-back direction by the end surface of the sleeve as described above, the distortion and stress concentration on the projecting base of the outward flange is prevented, thereby improving the durability of the outward flange. This can be further improved.

  In the above description, when the outer cylinder is made of resin, as described above, it is possible to effectively prevent damage at the protruding base portion of the outward flange.

1 and 2 are cross-sectional views each including a central axis showing an embodiment of the present invention, in which 1 indicates the entire elastic bushing.
The elastic bush 1 can be made of resin, metal, or the like. A cylindrical elastic body, for example, a rubber elastic body 3 is joined to the inner peripheral surface of the outer cylinder 2 by vulcanization bonding, adhesive bonding, or the like. The outer cylinder 2 protrudes radially outward at the rear end of the elastic bush 1 in the press-fitting direction with respect to the rigid sleeve 5 shown by the phantom line in FIG. An outward flange 6 in surface contact with the outer flange 5a is provided, and a flange portion of the rubber elastic body 3 is joined to the back surface of the outward flange 6, and in particular, the sleeve 5 of the outward flange 6 is formed. The contact surface 7 with the end surface 5a is an inclined surface facing outward in the radial direction.

Here, the elastic bush 1 shown in FIG. 1 has a substantially constant thickness of the outward flange 6 , whereas the bush 1 shown in FIG. 2 has a thickness of the outward flange 6 in the radially outward direction. It is different in that it is gradually reduced toward.

By the way, as shown in the figure, the entire contact surface 7 is a frustoconical inclined surface facing outward in the radial direction. The frustoconical surface is provided at least in the peripheral portion of the contact surface 7. It is preferable for improving the adhesion with the end face 5a.
When such a truncated conical surface is employed, the inclination angle θ with respect to the plane perpendicular to the central axis line cl of the bush 1 is in the range of 1 to 30 ° to prevent damage to the outward flange 6 and the like. At the same time, it is preferable to secure the adhesion of the contact surface 7 to the sleeve end surface 5a.

Here, this contact surface 7 of the outward flange 6 is regardless of whether or not the outer cylinder 2 is made of resin, and regardless of whether or not a frustoconical surface is left in the periphery of the contact surface 7, The curved surface may be convex or concave toward the outside in the radial direction. In this case, the convex or concave curved surface is made plastic or elastic on a flat surface when the sleeve end surface 5a abuts against the contact surface 7. By deforming, the contact surface 7 can be brought into close contact with the sleeve end surface 5a when the press-fitting of the elastic bush 1 is completed.
This can be performed particularly smoothly when the outer cylinder 2 is made of resin and the flexibility of the outward flange 6 is increased.

Thus, the contact surface 7, if including a curved surface in a part thereof, of the curved surface, the inclination angle θ with respect to a plane perpendicular to the center axis cl, be in the range of the same 1 to 30 ° with the aforementioned, It is preferable to prevent the outward flange 6 from being damaged and to secure the adhesion of the contact surface 7 to the sleeve end surface 5a.
In this case, the inclination angle θ is the average value of the intersection angles of the tangent lines drawn on the curved surface within the cross section including the central axis line cl with respect to the orthogonal plane.

  More preferably, in the elastic bush 1 as described above, the contact surface 7 is smoothly and continuously connected to the cylindrical portion 8 of the outer cylinder 2 via a curve within a cross section including the central axis line cl. During the push-back deformation of 6, the concentration of strain and stress on its protruding base is prevented.

  In the elastic bush 1 configured as described above, when it is press-fitted into the rigid sleeve 5 as shown in FIG. With the approach to the flange 6, the outward flange 6 undergoes a falling deformation as illustrated in FIG. 3B, and after the sleeve end surface 5 a abuts the outward flange 6, the flange 6 Is pressed back by the sleeve 5 and deformed by pushing back in the direction opposite to the falling-down direction, and when the press-fitting is completed, the contact surface 7 comes into surface contact with the sleeve end surface 5a and reaches a position almost perpendicular to the central axis line cl. Will be displaced.

  In this case, since all of the contact surfaces 7 of the embodiment have an initial form that is an inclined surface facing radially outward, the contact surface 7 is deformed by being pushed back to a position where it comes into surface contact with the sleeve end surface 5a. The absolute deformation amount of the facing flange 6 is considerably smaller than that of the prior art shown in FIG. 3, whereby the distortion and stress generated in the protruding base portion of the outward flange 6 are also effectively reduced as compared with the prior art. In addition, since the press-fitting resistance due to the deformation resistance of the outward flange 6 can be effectively reduced and the smooth complete assembly of the elastic bush 1 can be easily performed, the outward flange 6 can be measured unexpectedly. In addition, it is possible to effectively prevent the dimensional variation of the assembly.

1 is a cross-sectional view including a central axis showing an embodiment of the present invention. It is sectional drawing similar to FIG. 1 which shows other embodiment. It is sectional drawing which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elastic bush 2 Outer cylinder 3 Rubber elastic body 4 Inner cylinder 5 Sleeve 5a End surface 6 Outward flange 7 Contact surface 8 Cylindrical part cl Center axis (theta) Inclination angle

Claims (2)

An outer cylinder and a cylindrical elastic body joined to the inner peripheral surface of the outer cylinder are press-fitted into the sleeve under a reduced diameter deformation of the outer cylinder, and the outer peripheral surface of the cylindrical portion of the outer cylinder is An elastic bush frictionally engaged with a peripheral surface,
An outward flange located at the rear end of the outer cylinder in the press-fitting direction and being in surface contact with the end face of the sleeve has an inclined surface facing the sleeve toward the radially outer side, and the sleeve of the outward flange The contact surface is a frustoconical surface at least in the periphery of the contact surface, and the inclination angle of the frustoconical surface with respect to a plane orthogonal to the central axis is in the range of 1 to 30 ° . The elastic bush according to claim 1, wherein the outer cylinder is made of resin.

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