JP2008168787A - Toe collect bush and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toe collect bush that can prevent generation of cracks at an end portion of a body rubber elastic element in the axial direction constituting a bush body portion, and has high durability. <P>SOLUTION: An outer cylindrical member 14 constituting a bush body portion 32 is subjected to a diameter reduction processing to vary a degree of pre-compression applied to a body rubber elastic element 16 in the circumferential direction. A peripheral edge portion 50 of an axial end surface 46 of the body rubber elastic element 16 positioned on a radial direction side to which a toe collect portion 36 protrudes, is positioned in an area with greater pre-compression, while the peripheral edge portion 50 of the axial end surface 46 of the body rubber elastic element 16 positioned on the opposite radial direction side is positioned in an area with lower pre-compression. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a related technology of a toe collect bush, which is a kind of suspension bush of an automobile, and is used particularly in a suspension mechanism of a torsion beam type rigid axle type, and is attached to a mounting part on the body side of left and right trailing arms. The present invention relates to a to-collect bush having a novel structure and a method for producing the same.

  Conventionally, in a torsion beam type rigid axle type suspension mechanism in an automobile, as a kind of suspension bush to be mounted on the body side of the left and right trailing arms connected by a torsion beam (also referred to as a twist beam or an intermediate beam) To collect Bush is known. In this to-collect bush, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-96616 (Patent Document 1), one axial direction of a bush main body portion in which an inner shaft member and an outer cylinder member are connected by a main rubber elastic body. The inner side inclined portion and the outer side inclined portion that protrude obliquely outward from the inner shaft member and the outer cylinder member are provided at the end portions of the inner side member and the to-collect portion in which the to-collect portion is connected.

  This to-collect bush is mounted on an automobile in such a state that the central axis of the bush body portion (the central axis of the inner shaft bracket and the outer tube bracket) is the vehicle lateral direction and the radial direction from which the to-collect portion protrudes is the vehicle longitudinal direction. The As a result, a component force action by the to-collect portion is exhibited with respect to a lateral load exerted during cornering of the vehicle, and the running stability of the vehicle can be improved by suppressing a change in toe of the wheel.

  However, in such a toe collect bush, damage such as a crack is likely to occur at a specific portion in the main rubber elastic body constituting the bush main body part, and it is difficult to obtain sufficient durability due to such damage. This has been clarified by the inventors. Specifically, in the main rubber elastic body, it is recognized that cracks and the like are likely to occur in the radially located portion where the to-collect portion protrudes in the outer peripheral edge portion of the rubber (near the fixing surface to the outer). It was.

  In response to this problem, the present inventor has conducted many experiments and studies, and has come to obtain new knowledge that it may be caused by the spring characteristics peculiar to the toe collect bush. That is, in the toe collect bush, since the toe collect part is formed only on one side in the radial direction located at the front or rear of the automobile with respect to the center axis, the inner shaft fitting is located on the front side of the vehicle with respect to the outer cylinder fitting. The inner shaft metal fitting and the outer cylinder metal fitting have different radial load-deflection characteristics depending on whether the inner shaft metal fitting is displaced relatively to the rear of the vehicle. Specifically, when the inner shaft bracket is displaced relative to the outer cylinder bracket in the same radial direction as the protruding direction of the to-collect portion, the compression spring of the to-collect rubber acts effectively, but on the contrary When the inner shaft bracket is displaced relative to the outer cylinder bracket in the radial direction opposite to the protruding direction of the to-collect portion, the to-collect rubber compression spring does not act. Therefore, compared to the former case, the latter case (when the inner shaft bracket is displaced relative to the outer tube bracket in the radial direction opposite to the protruding direction of the to-collect portion) is more suitable for the inner shaft bracket. The amount of relative displacement with respect to the outer cylinder fitting tends to increase.

  Due to this, in the main rubber elastic body, the amount of tensile deformation increases in the portion located on one side in the radial direction that is the protruding direction of the to collect portion with respect to the inner shaft bracket, while the opposite radial direction The amount of compressive deformation increases in the portion located on the other side. In particular, it has also been confirmed that in the main rubber elastic body, cracks are likely to occur on the axial end surface on the side opposite to the to-collect portion, where the restraining force by the inclined portion constituting the to-collect portion is not exerted.

In general, the elastic rubber body has a lower durability against tensile deformation than compression deformation, so that the amount of tensile deformation increases, and the elastic elastic body is positioned on one side in the radial direction that is the protruding direction of the toe collect portion with respect to the inner shaft bracket. However, the occurrence of cracks in the part that is likely to become a problem is more problematic, however, if the main rubber elastic body is subjected to large pre-compression by greatly reducing the diameter of the outer cylinder fitting after vulcanization molding of the main rubber elastic body, The occurrence of cracks due to tensile stress in the part is suppressed, but instead, the amount of compressive deformation acting on the part located on the other side in the radial direction opposite to the protruding direction of the to-collect part with respect to the inner shaft bracket is reduced. It has been confirmed by the present inventor that a problem arises that cracks due to compressive deformation are likely to occur because they become too large. Therefore, simply applying large pre-compression to the main rubber elastic body does not provide an effective solution to the durability problem in the main rubber elastic body as described above.
JP 2006-96616 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is that the main rubber is not damaged in the mounted state on the vehicle without damaging the desired spring characteristics. An object of the present invention is to provide a toe collect bush having a novel structure in which damage such as cracks in an elastic body is reduced or avoided and excellent durability is exhibited, and a method for manufacturing the toe collect bush.

  Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible. In addition, aspects or technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or can be understood by those skilled in the art from those descriptions. It should be understood that it is recognized on the basis of.

  That is, a feature of the present invention is that the inner shaft member and the outer cylindrical member spaced apart from the inner shaft member are connected by a cylindrical main rubber elastic body interposed between the radially opposed surfaces. While constituting the bush main body portion, the inner shaft member is provided with an inner inclined portion that is inclined outward in the axial direction and protrudes obliquely outward in one radial direction at one axial end portion of the inner shaft member. The outer cylindrical member is inclined outward in the axial direction at one end portion in the axial direction of the outer cylinder member and protrudes obliquely outward in one radial direction so as to be opposed to the inner shaft member. A to-collect portion is formed by connecting the opposing surfaces of the inner-side inclined portion and the outer-side inclined portion with a to-collect rubber elastic body, and further, the inner-side inclined portion and the outer-side inclined portion. How to protrude The first axially extending between the inner shaft member and the outer cylindrical member in the main rubber elastic body constituting the bush main body portion is located on both sides of the inner shaft member in the radial direction to be In a to-collect bush formed by opening a slit and a second slit on the end surface in the axial direction opposite to the to-collect part, the outer cylinder member constituting the bush main body part is subjected to diameter reduction processing. Pre-compression is applied to the main rubber elastic body, and the pre-compression ratio is at least at the outer peripheral edge on the other end side in the axial direction of the main rubber elastic body, which is located on the opposite side of the toe correct portion in the axial direction. In the toe collect bush, the radial side from which the toe collect part protrudes has a larger precompression ratio than the opposite radial side.

  In such a to-collect bush having a structure according to the present invention, the main rubber elastic body constituting the bush main body portion is provided with a portion with a large pre-compression and a small portion at different positions in the circumferential direction. And, the direction of protrusion of the to collect portion with respect to the inner shaft member among the to collect portion and the axially opposite end portion of the main rubber elastic body is a portion in which crack occurrence considered to be caused by tensile stress is a problem. The outer peripheral edge portion fixed to the outer cylinder member is set in a region having a large pre-compression. On the other hand, the direction in which the to collect portion protrudes with respect to the inner shaft member among the to collect portion and the axially opposite end portion of the main rubber elastic body, which is a portion in which cracking considered to be caused by compressive stress is a problem. The outer peripheral edge portion fixed to the outer cylinder member is set in a region where the pre-compression is small.

  As a result, in the rubber elastic body of the main body, the portion where the occurrence of cracks, which is considered to be caused by the above-described tensile stress, is a problem, a large pre-compression is exerted, and the tensile stress generated by the external force action in the mounted state is suppressed. As a result, the occurrence of cracks is suppressed. In addition, in a portion where crack generation considered to be caused by the above-described compressive stress is a problem, excessive pre-compression is avoided, and the compressive stress generated by the external force action under the mounted state is reduced, thereby causing a crack. Occurrence is suppressed. As a result, the durability of the main rubber elastic body and thus the toe collect bush is advantageously ensured.

  In addition, in the toe collect bush configured according to the present invention, the elastic deformation amount of the main rubber elastic body and the toe collect rubber elastic body is not unnecessarily limited to prevent the occurrence of cracks. In any of the to-collect portions, the basic spring characteristics and the like can be sufficiently ensured.

  In the present invention, for example, the following modes can be adopted. That is, the outer cylindrical member has a large-diameter portion formed at the axial center portion of the cylindrical portion, and a small-diameter portion on the axial direction opposite to the outer-side inclined portion with respect to the large-diameter portion. The large diameter portion is fitted and fixed in a predetermined mounting hole, while the diameter reduction ratio is different in the circumferential direction between the large diameter portion and the small diameter portion in the axial direction. A deformed cylindrical portion, and the deformed tubular portion has a larger radial dimension on the opposite radial side than the protruding radial side of the to-collect portion. A mode in which the radial dimension of the cylindrical part is set in the dimension range between the small diameter part and the large diameter part of the outer cylindrical member over the entire circumference can be adopted in the present invention.

  In such an aspect, the outer diameter is the same as or smaller than that of the large-diameter portion that is fitted and fixed to the mounting hole for assembling the bush provided in the suspension member or the body-side member. Since the deformed cylindrical portion is formed, troubles in assembling the toe collect bush into the mounting hole due to the presence of the deformed tubular portion can be avoided.

  In the present invention, for example, the following modes can be adopted. That is, in the present invention, it is possible to adopt a mode in which the outer cylindrical member is formed with a constricted portion having a smaller diameter than the large diameter portion on the axial center side at the axial end portion side on the toe collect portion side. It is.

  By providing the constricted portion on the outer cylinder member according to such an embodiment, the strength of the member can be improved by the rib action of the constricted portion. In addition, since the outer side inclined portion extends obliquely outward from the opening end of the constricted portion, the opposing area of the outer side inclined portion to the inner inclined portion is radially inward by the constricted portion. The target to collect action can be improved.

  In the present invention, for example, the following modes can be adopted. That is, at one end in the axial direction of the inner shaft member, there is provided a constraining plate portion that extends outward in the direction perpendicular to the axis over the entire circumference. The inner side inclined portion is configured by being inclined obliquely outward, and the restraining plate portion is overlapped and fixed to one axial end surface of the main rubber elastic body. A mode in which the first and second slits have a bottomed shape that opens only on the other end surface in the axial direction can be employed in the present invention.

  By adopting the restraint plate portion according to such an embodiment, the end portion on the one side in the axial direction of the main rubber elastic body (the end portion on the axial direction side where the to collect portion is located) is secured by the restraint plate portion fixed thereto. Since deformation is constrained, large deformation is suppressed. As a result, the occurrence of defects such as cracks due to large deformation of the main rubber elastic body is effectively prevented even on one end side in the axial direction. In addition, the restraining plate part should just be provided fixed with respect to the inner shaft member, and may be integrally formed with the inner shaft member or may be fixed separately.

  In the present invention, for example, the following modes can be adopted. That is, the other end surface in the axial direction of the main rubber elastic body is a tapered inclined surface extending outward in the axial direction from the outer cylindrical member side toward the inner shaft member side inward in the radial direction. It is possible to adopt a mode in which the taper inclination angle is constant over the entire circumference in the circumferential direction.

  According to such an aspect, by forming the other end surface in the axial direction of the main rubber elastic body with a tapered inclined surface, the rubber volume of the main rubber elastic body can be advantageously ensured even on the inner peripheral side, and the main rubber elastic body can be molded. In the mold, it is possible to easily form the molding surface shape of the other axial end surface with a simple shape having no specific direction in the circumferential direction.

  In the present invention, for example, the following modes can be adopted. That is, the main rubber elastic body that constitutes the bush main body portion has a radial direction perpendicular to the opposing direction of the first slit and the second slit, on both sides of the inner shaft member. The aspect in which the third slit and the fourth slit extending in the axial direction between the inner shaft member and the outer cylindrical member are formed to be opened in the axial end surface opposite to the to-collect portion is adopted. Is possible.

  By adopting the third and fourth slits according to such an aspect, a greater degree of freedom in tuning the bush spring characteristics in the vehicle vertical direction is ensured. By the way, when these third and fourth slits are formed, in the main rubber elastic body having the four leg portions extending radially between the adjacent slits in the first to fourth circumferential directions, the rubber volume is The occurrence of cracks and the like is a concern as a larger problem due to the reduction in size and the stress concentration effect caused by the slits. However, in the present invention, as described above, in the main rubber elastic body of the four leg structure, tensile stress tends to be a problem, and a large precompression is exerted on one side in the radial direction where the to-collect portion is located. Therefore, the tensile stress can be relaxed and the compressive stress is likely to be a problem. On the other side in the radial direction opposite to the to-collect portion, since the pre-compression is small, the generation of excessive compressive stress is suppressed. Durability can also be secured.

  Further, the present invention relating to a manufacturing method is characterized in that a cylindrical main body rubber elastic member in which an inner shaft member and an outer cylindrical member spaced apart from the inner shaft member are interposed between their radially opposed surfaces is provided. An inner side inclined portion that constitutes a bush main body portion by connecting with a body, and is inclined outward in the axial direction at one end in the axial direction of the inner shaft member and protrudes obliquely outward in one radial direction. At one end in the axial direction of the outer cylinder member, and is inclined obliquely outward in one radial direction so as to be spaced apart from and opposed to the inner shaft member. An outer side inclined portion is provided, and a to-collect portion is formed by connecting between the opposing surfaces of the inner side inclined portion and the outer side inclined portion with a to-collect rubber elastic body, and further, the inner side inclined portion and the outer side Side tilt Between the inner shaft member and the outer cylinder member of the main rubber elastic body constituting the bush main body portion, positioned on both sides of the inner shaft member in the radial direction that is the protruding direction of the portion in the axial direction The first slit and the second slit extending are a method of manufacturing a toe collect bush formed by opening an axial end face opposite to the toe collect part, and the inner and outer peripheral surfaces of the main rubber elastic body An integral vulcanized molded product in which an inner shaft member and the outer cylindrical member are vulcanized and bonded is prepared, and the outer cylindrical member in the integral vulcanized molded product is subjected to a diameter reduction process so that the main rubber elastic body is preliminarily formed. When applying compression, the pre-compression rate of the main rubber elastic body is varied in the circumferential direction at least in a portion where the other end side in the axial direction of the main rubber elastic body is located on the opposite side to the to-collect portion. , In the manufacturing method of the toe collect bushing radial side of the toe collect portion protrudes is so precompression rate is greater than the radial side opposite thereto.

  According to such a method of the present invention, the toe collect bush having a novel structure as described above, which can advantageously obtain excellent durability without substantially reducing required vibration isolating characteristics, toe collect performance and the like. Can be efficiently manufactured and provided.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, the toe collect bush 10 as one Embodiment of this invention is shown by FIGS. The to-collect bush 10 includes an inner cylindrical member 12 as an inner shaft member and an outer cylindrical member 14 as an outer cylindrical member that are spaced apart from each other in the radial direction, and between the inner and outer cylindrical members 12 and 14. The main rubber elastic body 16 is interposed, and the metal fittings 12 and 14 are elastically connected.

  More specifically, the inner cylinder fitting 12 has a straight small-diameter cylindrical shape, and extends around the entire circumference of the inner cylinder fitting 12 near the end in one axial direction (left side in FIG. 1). Thus, a fixed plate 18 is fixed as a constraining plate extending outward in the direction perpendicular to the axis. The fixing plate 18 is formed of a rigid member such as a press fitting, and a mounting hole 20 is provided at the center. Then, the inner cylinder fitting 12 is inserted into the mounting hole 20, and the inner peripheral edge of the mounting hole 20 is welded to the inner cylinder fitting 12, whereby the fixing plate 18 is fixed to the inner cylinder fitting 12.

  Further, the fixed plate 18 has a substantially fan shape in which the upper half portion in the upper side in FIG. 1 becomes wider as the distance from the inner tube fitting 12 increases, and the fixing plate 18 is inclined with respect to the central axis 22 of the inner tube fitting 12. And protrudes obliquely outward in the axial direction. Further, the inner inclined portion 19 is substantially entirely protruded outward at a substantially constant inclination angle: θa with respect to the central axis 22 of the inner cylindrical metal member 12. An inclined surface inclined with respect to is formed. That is, the inner side inclined portion 19 is constituted by the upper half portion of the fan shape. In addition, the inner side inclined portion 19 has a radially outward projecting tip portion that extends to the outer cylinder fitting 14 by projection in the axial direction.

  Furthermore, reinforcing ribs 26 (bending toward the axially outward direction of the inner cylinder fitting 12) are formed at both side edges in the width direction of the fixing plate 18 (respective leading end portions corresponding to the left and right sides in FIG. 2). 3) is integrally formed. Further, below the fixed plate 18, an abutting portion 27 that is spread out in a substantially flat plate shape and is spaced apart in the axially outward direction of the outer cylinder fitting 14 is integrally formed.

  On the other hand, the outer cylinder fitting 14 has a large-diameter cylindrical shape. When the outer cylinder fitting 14 is inserted into the inner cylinder fitting 12, the outer cylinder fitting 14 is separated from the inner cylinder fitting 12 in the radial direction and is the same as the inner cylinder fitting 12. It is arranged on the central axis (22). The axial length of the outer cylinder fitting 14 is shorter than that of the inner cylinder fitting 12, and both axial end portions of the inner cylinder fitting 12 are protruded axially outward from the outer cylinder fitting 14. In addition, a flange-like portion 28 that protrudes radially outward and continuously extends in the circumferential direction is integrally formed on the opening peripheral edge of one axial direction (left side in FIG. 1) of the outer cylindrical metal member 14.

  And the outer side inclination part 30 is formed in a part (upper part in FIG. 1, 2) on the periphery of the flange-shaped part 28. As shown in FIG. The outer side inclined portion 30 is extended radially outward of the flange-shaped portion 28, and has the same inclination angle θb as the inner side inclined portion 19 with respect to the central axis 22 of the inner cylindrical metal member 12, It is inclined outward in the axial direction of the outer cylinder fitting 14, is separated in an oblique axis direction with respect to the inner side inclined portion 19 projecting from the inner cylinder fitting 12, and is substantially parallel to the inner side inclined portion 19. It is made to oppose to. Thereby, in this embodiment, the distance between the opposing surfaces of the inner side inclination part 19 and the outer side inclination part 30 is made substantially constant.

  Further, the outer side inclined portion 30 has a radially outward protruding tip edge portion having an arc shape larger in diameter than the inner side inclined portion 19, and a circumferential length of the protruding tip edge portion is also increased. The inner side inclined portion 19 is made larger than the inner side inclined portion 19 so as to protrude from both sides of the inner side inclined portion 19 in the circumferential direction.

  Furthermore, the main rubber elastic body 16 has a thick, generally cylindrical shape as a whole, and is interposed between the radially opposed surfaces of the inner cylinder fitting 12 and the outer cylinder fitting 14. Then, the inner and outer peripheral surfaces of the main rubber elastic body 16 are vulcanized and bonded to the outer peripheral surface of the inner cylindrical metal fitting 12 and the inner peripheral surface of the outer cylindrical metal fitting 14, respectively. It is formed as an integrally vulcanized molded product having the tube fittings 12 and 14. Further, in the present embodiment, the bush main body portion 32 is configured by connecting the inner and outer cylinder fittings 12 and 14 with the main rubber elastic body 16.

  Furthermore, the main rubber elastic body 16 also extends between the opposing surfaces of the inner side inclined portion 19 and the outer side inclined portion 30, and thus the opposing surfaces of the inner side inclined portion 19 and the outer side inclined portion 30. A to-collect rubber 34 filled over the entire space is formed integrally with the main rubber elastic body 16. In the present embodiment, the thickness dimension of the to-collect rubber 34 is substantially the same throughout.

  As is clear from this, in the present embodiment, the fixed plate 18 provided on only one side in the radial direction (the upper side in FIGS. 1 and 2) sandwiching the inner cylindrical metal member 12, the outer side inclined portion. 30 and the to-collect rubber 34 constitute a to-collect portion 36 that is asymmetric in the direction perpendicular to the axis (radial direction) orthogonal to the central axis 22 of the inner cylinder fitting 12.

  Further, the outer cylindrical metal member 14 has different diameters in the axial direction and the circumferential direction in the cylindrical part constituting the bush body portion 32. Specifically, as shown in FIG. 1, from the side where the to-collect portion 36 is located, a small diameter constricted portion 35, a large diameter large diameter portion 37, and a deformed cylinder whose diameter is varied in the circumferential direction. The shape portion 38 and the small-diameter small-diameter portion 39 are provided. In the present embodiment, the constricted portion 35 and the small diameter portion 39 have substantially the same diameter. Further, in the present embodiment, by forming the constricted portion 35, the outer side inclined portion 30 is formed to extend obliquely outward from the opening end portion of the constricted portion 35. As a result, the outer side inclined portion is formed. The opposing area of the portion 30 with respect to the inner inclined portion 19 spreads radially inward by the constricted portion 35 and is advantageously ensured.

  Further, particularly in the present embodiment, each of the constricted portion 35 and the small diameter portion 39 has a cylindrical shape extending in the axial direction with a substantially constant inner and outer diameter size. The large-diameter portion 37 positioned at the substantially central portion in the axial direction of the outer cylinder fitting 14 is a portion having a larger diameter than the constricted portion 35 and the small-diameter portion 39, and in the large-diameter portion 37, A large-diameter tapered portion 37b that smoothly connects the inner and outer peripheral surfaces to the constricted portion 35, and a large-diameter cylindrical portion having a cylindrical shape with a substantially constant inner and outer diameter, in order from the side where the to-collect portion 36 is positioned in the axial direction. 37a is integrally formed. The constricted portion 35, the large diameter portion 37, and the small diameter portion 39 are all in the shape of a rotating body around the central axis 22.

  Further, in the present embodiment, a deformed cylindrical portion 38 having a different diameter in the circumferential direction is formed at an intermediate portion in the axial direction between the large diameter portion 37 and the small diameter portion 39. In such a deformed cylindrical portion 38, the inner and outer diameters of the outer cylindrical metal fitting 14 having a constant thickness are gradually changed in the axial direction between the inner and outer diameters of the large diameter portion 37 and the small diameter portion 39. Thus, the inner and outer peripheral surfaces are smoothly connected to the large diameter portion 37 and the small diameter portion 39. More specifically, in the modified cylindrical portion 38, in order from the side where the to-collect portion 36 is formed in the axial direction, a large-diameter portion-side modified cylindrical portion 38a and a small-diameter portion-side modified cylindrical portion 38b, It is connected smoothly and formed continuously.

  First, as shown in FIG. 1, the large-diameter portion-side deformed cylindrical portion 38 a has a diameter dimension only in a substantially semicircular portion on the radial side (upper side in FIG. 1) from which the to-collect portion 36 protrudes. It is changed in the direction. On the other hand, in the small-diameter portion-shaped deformed cylindrical portion 38b, the diameter dimension is changed in the axial direction only in the substantially semicircular portion on the opposite side (lower side in FIG. 1) to the protruding radial side of the to-collect portion 36. It has been. Thereby, as shown in FIG. 4, the deformed cylindrical portion 38 has a radial side (upper side in FIG. 4) from which the to-collect portion 36 protrudes, and an opposite radial side (lower side in FIG. 4). ) Is an irregular cylindrical shape having a larger radial dimension. Further, as is clear from this, in the outer cylinder fitting 14 of the present embodiment, the cylindrical part constituting the bush main body part 32 is a constricted part 35, a large diameter part 37, a deformed cylindrical part 38, and a small diameter part 39. It is made into the stepped cylindrical shape formed from.

  Further, the outer cylindrical metal member 14 is subjected to diameter reduction after the vulcanization molding of the main rubber elastic body 16, so that the main rubber elastic body 16 is pre-compressed in the radial direction. Here, the integrally vulcanized molded product 48 before the diameter reduction processing is shown in FIGS. As shown in these figures, in the present embodiment, the outer cylinder fitting 14 before diameter reduction employed in the vulcanization molding is configured such that only the portion corresponding to the constricted portion 35 in the cylindrical portion is the other portion ( The portion corresponding to the large-diameter portion 37, the deformed cylindrical portion 38, and the small-diameter portion 39) has a smaller diameter, and the portions corresponding to the large-diameter portion 37, the deformed tubular portion 38, and the small-diameter portion 39 are constant. It has a cylindrical shape having an inner and outer diameter.

  Then, the cylindrical portion of the outer tube fitting 14 in the integrally vulcanized molded product 48 is subjected to diameter reduction processing such as drawing using a die such as an eight-way drawing or a sixteen-way drawing. The to collect bush 10 as shown by 1-4 will be obtained. In this embodiment, in addition to the large-diameter portion 37, the deformed cylindrical portion 38, and the small-diameter portion 39, the constricted portion 35 is subjected to diameter reduction processing. Here, the diameter reduction ratio applied to the large diameter portion 37 (that is, the precompression ratio exerted on the main rubber elastic body 16 by the diameter reduction) is different from the diameter reduction ratio applied to the small diameter portion 39. Specifically, the diameter reduction rate can be expressed by, for example, the following formula, but this diameter reduction rate is larger in the small diameter portion 39 than in the large diameter portion 37.

Reduction ratio = (Inner diameter dimension of outer cylinder fitting 14 before drawing process−Inner diameter dimension of outer cylinder fitting 14 after drawing process) / Inner diameter dimension of outer cylinder fitting 14 before drawing process That is, small diameter portion 39 and large diameter portion Each diameter reduction ratio of 37 is as follows.
Reduction ratio of small diameter portion 39 = (D−Da) / D
Reduction ratio of large diameter portion 37 = (D−Db) / D
However, Da <Db

  Further, in the deformed cylindrical portion 38, the diameter reduction rate applied to the deformed cylindrical portion 38 (that is, the precompression rate exerted on the main rubber elastic body 16 by the diameter reduction) is varied in the circumferential direction. More specifically, in the deformed tubular portion 38, the radial side from which the to-collect portion 36 protrudes has a larger precompression rate than the opposite radial side. Further, in the large-diameter side modified cylindrical portion 38a in FIG. 1, the diameter-reducing rate in the irregular-shaped cylindrical portion 38 is the axial reduction ratio of the substantially semicircular portion on the radial side from which the to-collect portion 36 protrudes. In addition, in the small-diameter portion side modified cylindrical portion 38b, the diameter reduction ratio of the substantially half-circular portion on the opposite side in the radial direction from the side on which the toe collect portion 36 protrudes is changed in the axial direction. It is like that. Thereby, the diameter reduction rate of the deformed cylindrical part 38 is set to a range between the diameter reduction rate of the small diameter part 39 and the diameter reduction rate of the large diameter part 37 in the outer cylinder fitting 14 over the entire circumference. . The constricted portion 35 is also reduced in diameter by an appropriate amount so that the tensile stress caused by the vulcanization shrinkage of the main rubber elastic body 16 is eliminated.

  On the other hand, the main rubber elastic body 16 is axially extended to the fixing plate 18 along the outer peripheral surface of the inner cylindrical metal member 12 even in a portion where the toe collect rubber 34 is not located (that is, the left and right sides or the lower portion in FIG. 2). Thus, the cover rubber 33 covering the outer peripheral surface of the fixed plate 18 is formed integrally with the main rubber elastic body 16. In particular, a stopper rubber 31 protruding inward in the axial direction is integrally formed with the cover rubber 33 at the abutting portion 27 of the fixed plate 18, and the contact of the fixed plate 18 is made via the stopper rubber 31. When the contact portion 27 strikes the flange-shaped portion 28 of the outer cylindrical metal member 14 in the axial direction, the stopper function in the axial direction is exhibited.

  Further, the main rubber elastic body 16 has first to fourth straight portions 40, 41, 42 as first to fourth slits extending in the axial direction between the radially opposing surfaces of the inner and outer cylindrical metal members 12, 14, respectively. , 43 are formed. In particular, in the present embodiment, any of the straight portions 40, 41, 42, 43 extends substantially straight in the axial direction, and one side in the axial direction where the fixed plate 18 is not fixed to the axial end surface (torcollect) It has a bottomed pocket shape that opens only on the other end side in the axial direction located on the right side in FIG.

  Further, as shown in FIG. 2, all of the four straight portions 40, 41, 42, and 43 extend in the axial direction with a substantially fan-shaped cross section that gradually spreads outward in the radial direction. As a result, the main rubber elastic body 16 radiates the inner and outer cylindrical metal members 12 and 14 in the radial direction by the four legs 44, 44, 44, 44 extending radially between two adjacent straight portions in the circumferential direction. It is set as the structure which is elastically connected by.

  The four straight portions 40, 41, 42, and 43 are substantially symmetrical with each other in pairs facing each other in the radial direction across the mount central axis (the central axis of the inner cylindrical fitting 12) 22. ing. That is, the first straight portion 40 and the second straight portion 41 that are opposed to each other in the vertical direction in FIG. The third straight part 42 and the fourth straight part 43 that are opposed to each other on the left and right in FIG. 2 have a substantially symmetrical cross-sectional shape. In particular, the first straight portion 40 and the second straight portion 41 located on both sides of the inner cylindrical metal member 12 in the radial direction (vertical direction in FIG. 2) in which the to-collect portion 36 protrudes in the radial direction are Compared to the third and fourth straight portions 42 and 43, the cross-sectional shape is greatly widened in the circumferential direction, and thus different spring characteristics are set in two radial directions orthogonal to each other.

  Further, elastic contact portions 45, 45 projecting radially inward from the outer peripheral inner surface are integrally formed with the main rubber elastic body 16 inside the first and second straight portions 40 and 41. ing. Due to the abutment of these elastic contact portions 45, 45 with respect to the inner cylinder fitting 12, a stopper function for limiting the relative radial displacement of the inner and outer cylinder fittings 12, 14 in a buffering manner is exhibited. Yes.

  In particular, in this embodiment, one axial end surface (the left end surface in FIG. 1) of the main rubber elastic body 16 is vulcanized and bonded to the fixed plate 18 directly or integrated with the to-collect rubber 34. Has been. As a result, at one end in the axial direction of the main rubber elastic body 16, the amount of elastic deformation is suppressed by the fixing plate 18, and the occurrence of cracks and the like due to excessive strain is suppressed.

  On the other hand, the other axial end surface (the right end surface in FIG. 1) of the main rubber elastic body 16 is exposed with a free surface between the inner and outer cylindrical fittings 12 and 14. The first to fourth straight portions 40, 41, 42, 43 are opened at the other axial end surface.

  Here, the other end surface in the axial direction of the main rubber elastic body 16 is a tapered inclined surface 46 extending outward in the axial direction from the outer cylinder fitting 14 toward the inner cylinder fitting 12 inward in the radial direction. ing. In other words, the other end surface in the axial direction of the main rubber elastic body 16 is shaped so as to be punched between the inner and outer cylindrical fittings 12 and 14, and extends over the entire circumference in the circumferential direction. The portion gradually becomes deeper as the axial depth dimension goes to the outer peripheral side than the inner peripheral portion.

  Further, on the other end surface in the axial direction of the main rubber elastic body 16, the axial depth dimension of the bottomed portion 50 in the squashed state is constant in the circumferential direction. In particular, in this embodiment, the inclination angle of the tapered inclined surface 46 of the main rubber elastic body 16 is constant, so that the position of the bottom 50 is constant on the circumference.

  That is, on the other end surface in the axial direction of the main rubber elastic body 16, the bottomed bottom portion 50 is positioned at an outer peripheral edge portion that is a fixing portion of the main rubber elastic body 16 to the outer tube fitting 14. The axial position of the bottom 50 is positioned at the axially central portion of the deformed tubular portion 38. In particular, in the present embodiment, the position of the bottom 50 is positioned on the boundary line between the large-diameter portion-side deformed tubular portion 38a and the small-diameter portion-side deformable tubular portion 38b.

  As a result, the position of the outer peripheral edge that is the portion where the main rubber elastic body 16 is fixed to the outer tube fitting 14 (that is, the position of the bottom 50) is positioned radially inward of the deformed tubular portion 38. Yes. That is, in the large-diameter portion-shaped deformed cylindrical portion 38a, the outer peripheral edge portion, which is the fixed portion of the main rubber elastic body 16 to the outer cylindrical metal fitting 14, is a substantially half circumferential portion in the radial direction in which the toe collect portion 36 protrudes (see FIG. 1 (upper side in FIG. 1), the radial dimension is changed in the axial direction, whereas in the substantially semicircular portion on the opposite side in the radial direction (lower side in FIG. 1), the radial dimension is constant in the axial direction. Thus, the diameter is the same as that of the large-diameter portion 37. On the other hand, in the small-diameter-side deformed cylindrical portion 38b, the diameter dimension of the substantially semicircular portion (lower side in FIG. 1) opposite to the protruding direction of the to-collect portion 36 is changed in the axial direction. However, the hollow in the hollowed out state is positioned inward in the radial direction of the small-diameter portion side deformed cylindrical portion 38b.

  Thus, in the to-collect bush 10 having such a structure, for example, a pair of trailing arms that support the left and right wheels of an automobile are connected and fixed to each other by a torsion beam extending in the vehicle width direction (vehicle left-right direction). A pair is assembled to the damped torsion beam suspension mechanism. That is, the outer cylinder fitting 14 is press-fitted and fixed at the large-diameter portion 37 with respect to the mounting holes extending in the vehicle width direction formed in the front end portions of the respective left and right trailing arms. By fixing to the vehicle body via a rod or the like, the toe collect bush 10 is mounted in a state where the left-right direction is the vehicle left-right direction and the up-down direction is the vehicle front-rear direction. In addition, at the front end portion of each trailing arm, the to-collect portion 36 is positioned inward in the vehicle left-right direction and the vehicle center in the front-rear direction so as to protrude from the bush body portion 32 toward the front of the vehicle. A pair of toe collect bushes 10, 10 on both the left and right sides are mounted symmetrically with respect to the extending symmetry axis (center line). In the toe collect bush 10 of the present embodiment, the deformed cylindrical portion 38 has an outer diameter that is the same as or smaller than that of the large-diameter portion 37 that is fitted and fixed in the mounting hole for assembling the bush. Therefore, troubles in assembling the toe collect bush into the mounting hole due to the presence of the deformed cylindrical portion 38 can be advantageously avoided.

  In this cornering state, when the vehicle is cornered, the centripetal force exerted from the tire in the left-right direction of the vehicle is exerted in the substantially axial direction between the inner and outer cylindrical fittings 12, 14 of each toe collect bush 10. On the basis of the component force generated between the inner side inclined portion 19 and the outer side inclined portion 30 via the to-collect rubber 34, the displacement of the torsion beam can be suppressed and the running stability can be improved. is there.

  By the way, in the toe collect bush 10 having the above-described structure, the inner and outer cylindrical metal fittings 12 and 14 are moved up and down in FIG. 2 by a radial load in the vehicle front-rear direction inputted at the time of sudden acceleration / deceleration or stepping over a step. The relative displacement is caused in the direction, and there is a concern about the occurrence of cracks or the like in specific parts of the main rubber elastic body 16 due to repeated load input. The distortion due to the vehicle longitudinal load in the main rubber elastic body 16 becomes large at the axial end portion (right end portion in FIG. 1) opposite to the to-collect portion 36 where the free surface is increased. Stress concentration is induced in the vicinity of the outer peripheral edge where the main rubber elastic body 16 is fixed to the outer cylindrical fitting 14, that is, in the bottom 50 of the axial end surface formed by the tapered inclined surface 46. In particular, in the vertical direction in FIG. 2, it is considered that due to the action of the to collect portion 36, the upper portion in FIG. 2 is caused by the tensile stress, particularly in the circumferential end portions 52, 52 of the first straight portion 40. 2 is concerned, and in the lower portion in FIG. 2, particularly in the circumferential end portions 54, 54 of the second straight portion 41, there is a concern that cracking is considered to be caused by compressive stress.

  Here, the bottom 50 of the axial end surface formed by the tapered inclined surface 46, which is a portion where cracks due to strain or stress in the main rubber elastic body 16 are a concern, is an outer cylinder fitting. 14 is positioned on the inner peripheral side of the deformed cylindrical portion 38. And in the large-diameter portion side deformed cylindrical portion 38a that is the portion where the bottom 50 is not reached in the axial direction, the diameter dimension on the side (the upper side in FIG. 1) from which the to collect portion 36 protrudes in the radial direction is It is made smaller than the diameter dimension of the direction opposite side (lower side in FIG. 1). That is, on the upper side in FIG. 1 of the large-diameter portion side deformed cylindrical portion 38a, the upper side of the main rubber elastic body 16 in FIG. The large pre-compression applied to the substantially circumferential part of the circumferential direction is effectively exerted on the main rubber elastic body 16 in the vicinity of the uppermost bottom 50 in FIG. As a result, in the main rubber elastic body 16 near the bottom 50 on the side where the to-collect portion 36 protrudes in the radial direction (upper side in FIG. 1), the generation of tensile stress during load input is reduced or avoided. As a result, the occurrence of cracks due to tension is prevented and excellent durability is exhibited.

  Further, in the small-diameter-side deformed cylindrical portion 38b, the shaft is more axial than the bottommost portion 50 of the axial end surface that is formed by the tapered inclined surface 46, which is a portion where cracks due to distortion or stress are a concern. In the outward direction, in FIG. 1, the diameter of the lower semicircular portion on the lower side is changed in the axial direction so that the diameter gradually decreases outward in the axial direction. Accordingly, the main rubber elastic body 16 in the vicinity of the lowermost bottom portion 50 in FIG. 1 where the occurrence of such cracks is concerned is substantially equivalent to the large diameter portion 37 with a smaller diameter reduction ratio than the small diameter portion 39. Pre-compression that is not so great that the main rubber elastic body 16 has been subjected to the diameter reduction processing or that the shrinkage at the time of vulcanization molding of the main rubber elastic body 16 is eliminated (the compression ratio is substantially zero). Only). As a result, in the main rubber elastic body 16 in the vicinity of the bottom 50 at the lower side in FIG. 1, the generation of compressive stress at the time of load input is suppressed, thereby preventing the occurrence of cracks due to compression. Excellent durability is exhibited.

  In addition, in the toe collect bush 10 having the structure according to the present invention, the elastic deformation amount of the main rubber elastic body 16 and the toe collect rubber 34 is not unnecessarily limited to prevent the occurrence of cracks. In any of the to-collect portions 36, the basic spring characteristics, vibration isolating performance, to-collect operation and the like can be sufficiently ensured.

  As mentioned above, although embodiment of this invention was explained in full detail, this is an illustration to the last, Comprising: This invention is not limited at all by the specific description in this embodiment.

  For example, in the above-described embodiment, the third and fourth straight portions 42 and 43 positioned in the vertical vertical direction when the vehicle is mounted are provided according to required spring characteristics and the like, and are essential in the present invention. Not.

  Further, in the to-collect part 36, the inclination angle of the inner side inclined part 19 and the outer side inclined part 30 can be set to be different from each other, or the fixing plate 18 extends downward in FIG. It is also possible to adopt a structure in which only the inner inclined portion 19 is formed as a semicircular shape in the circumferential direction without being provided, and no axial stopper mechanism is provided.

  Further, the depth dimension of the bottom 50 in FIG. 1 is also set in consideration of the required vibration isolation performance, spring rigidity, durability, and the like. For example, the bottom 50 in FIG. 1 can be positioned at the axial central portion of the small diameter portion 39 or at the axial central portion of the large diameter portion 37.

  Further, the inner cylinder fitting 12 and the outer cylinder fitting 14 are relatively eccentrically arranged in the direction perpendicular to the axis in the non-load input state before installation in consideration of the static load in the direction perpendicular to the axis exerted in the installation state. May be.

The longitudinal cross-sectional view of the to-collect bush as one Embodiment of this invention. The right view in FIG. III-III sectional explanatory drawing in FIG. IV-IV sectional drawing in FIG. The longitudinal cross-sectional view before the diameter reduction process of the toe collect bush shown by FIG. 1 is performed. The right view in FIG.

Explanation of symbols

10: Toe collect bush, 12: Inner cylinder fitting, 14: Outer cylinder fitting, 16: Main rubber elastic body, 19: Inner side inclined part, 30: Outer side inclined part, 32: Bush main part, 34: Toe collect rubber 36: Toe correct part, 38: Deformed cylindrical part, 40: First curb part, 41: Second curb part, 46: Tapered inclined surface, 50: Bottom part

Claims (7)

While constituting the bush main body part by connecting the inner shaft member and the outer cylindrical member spaced apart on the outer side with a cylindrical main body rubber elastic body interposed between the radially opposed surfaces thereof, An inner-side inclined portion that is inclined outward in the axial direction and protrudes obliquely outward in one radial direction is provided at one axial end of the inner shaft member, and one axial end of the outer cylindrical member is provided Provided with an outer side inclined portion that is inclined outward in the axial direction, protrudes obliquely outward in one radial direction, and is spaced apart and opposed to the inner shaft member. A to-collect portion is formed by connecting opposing surfaces of the outer inclined portion with a to-collect rubber elastic body, and further, the inner shaft in the radial direction that is the protruding direction of the inner inclined portion and the outer inclined portion. Sandwiched material The first slit and the second slit extending in the axial direction between the inner shaft member and the outer cylinder member in the main rubber elastic body constituting the bush main body portion are located on the side, and the toe collect portion In the toe collect bush formed by opening in the axial end surface opposite to
The outer cylindrical member constituting the bush main body portion is subjected to a diameter reduction process so that the main rubber elastic body is pre-compressed, and at least the axially opposite side of the to collect portion The pre-compression rate is different in the circumferential direction at the outer peripheral edge of the main rubber elastic body at the other end in the axial direction. The pre-compression is larger on the radial side where the toe collect part projects than on the opposite radial side. The to-collect bush is characterized by its rate.   The outer cylinder member has a large-diameter portion formed at the axial center portion of the cylindrical portion, and a small-diameter portion formed on the axial direction opposite to the outer-side inclined portion with respect to the large-diameter portion. The large-diameter portion is adapted to be fitted and fixed in a predetermined mounting hole, while the large-diameter portion and the small-diameter portion are deformed in such a manner that the diameter reduction ratio is different in the circumferential direction between the large-diameter portion and the small-diameter portion. A tubular portion is provided, and the deformed tubular portion has a larger radial dimension on the opposite radial side than the projecting radial side of the to collect portion, and the deformed tubular shape 2. The toe collect bush according to claim 1, wherein a radial dimension of the part is set to a dimension range between the small diameter part and the large diameter part of the outer cylindrical member over the entire circumference.   3. The toe collect bush according to claim 2, wherein a constricted portion having a smaller diameter is formed on the outer cylindrical member on an axial end portion side on the toe collect portion side than a large diameter portion on the axial center side.   At one end in the axial direction of the inner shaft member, there is provided a restraining plate portion that extends outward in the direction perpendicular to the axis over the entire circumference, and this restraining plate portion is inclined outward in the axial direction at one place on the circumference. The inner side inclined portion is configured by being inclined toward the first direction, and the first and second restraint plate portions are overlapped and fixed to one end surface in the axial direction of the main rubber elastic body. The toe collect bush according to any one of claims 1 to 3, wherein the second slit has a bottomed shape that opens only in the other axial end surface.   The other end surface in the axial direction of the main rubber elastic body is a tapered inclined surface extending outward in the axial direction from the outer cylinder member side toward the inner shaft member side in the radial direction. The toe collect bush according to any one of claims 1 to 4, wherein the taper inclination angle is constant over the entire circumference in the circumferential direction.   The main rubber elastic body constituting the bush main body portion includes, on both sides of the inner shaft member sandwiched in the radial direction perpendicular to the opposing direction of the first slit and the second slit, 6. The third slit and the fourth slit extending in the axial direction between the inner shaft member and the outer cylindrical member are formed to open in an axial end surface opposite to the to-collect portion. The toe collect bush according to any one of the above. While constituting the bush main body part by connecting the inner shaft member and the outer cylindrical member spaced apart on the outer side with a cylindrical main body rubber elastic body interposed between the radially opposed surfaces thereof, An inner-side inclined portion that is inclined outward in the axial direction and protrudes obliquely outward in one radial direction is provided at one axial end of the inner shaft member, and one axial end of the outer cylindrical member is provided Provided with an outer side inclined portion that is inclined outward in the axial direction, protrudes obliquely outward in one radial direction, and is spaced apart and opposed to the inner shaft member. A to-collect portion is formed by connecting opposing surfaces of the outer inclined portion with a to-collect rubber elastic body, and further, the inner shaft in the radial direction that is the protruding direction of the inner inclined portion and the outer inclined portion. Sandwiched material The first slit and the second slit extending in the axial direction between the inner shaft member and the outer cylinder member in the main rubber elastic body constituting the bush main body portion are located on the side, and the toe collect portion A toe collect bush formed by opening in the axial end surface opposite to
An integral vulcanized molded product in which the inner shaft member and the outer cylindrical member are vulcanized and bonded to the inner and outer peripheral surfaces of the main rubber elastic body is prepared, and the diameter of the outer cylindrical member in the integral vulcanized molded product is reduced. When pre-compression is applied to the main rubber elastic body after processing, the main rubber elastic body has a pre-compression rate at least the other end in the axial direction of the main rubber elastic body positioned on the opposite side to the to-collect portion. The toe collect bush is characterized in that the pre-compression ratio is different in the circumferential direction in the portion where the side is located so that the radial side from which the toe collect portion protrudes is larger than the opposite radial side. Production method.

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