Anti-vibration bush and method for manufacturing Anti-vibration bush

Abstract

To provide a novel vibration control bush capable of compatibly and further stably realizing a hard spring characteristic in a direction perpendicular to an axis and a soft spring characteristic in a twisting or wrenching direction.SOLUTION: In the vibration control bush 10, a bulge part 18 is provided on an inner shaft member 12, an interring 24 is arranged between the inner shaft member 12 and an outer cylinder member 14, and a body rubber elastic body 16 is composed of an inner layer rubber elastic body 26 and an outer layer rubber elastic body 28. The axially opposite end portions of the inner ring 24 are provided with reduced-diameter inner inclined portions 36, the axially opposite end portions of the outer tubular member 14 are provided with reduced-diameter outer inclined portions 22, the axially central portion of the inner ring 24 is formed into a straight cylindrical shape, and the inner rubber elastic body 26 and the outer rubber elastic body 28 are directly fixed at their axially opposite end portions to the inner ring 24 or the outer tubular member 14, and are compressed and deformed in the radial direction by the inner inclined portions 36 or the outer inclined portions 22.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vibration-isolating bushing, such as a suspension bushing used in the suspension mechanism of an automobile, and a method for manufacturing the vibration-isolating bushing. [Background technology]

[0002] Conventionally, for example, in automobiles, vibration-isolating bushings such as suspension bushings used in suspension mechanisms have been adopted. As proposed in, for example, Japanese Patent Laid-Open No. 2015-10627 (Patent Document 1) and Japanese Patent Laid-Open No. 2022-10591 (Patent Document 2), these vibration-isolating bushings have a structure in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-10627 [Patent Document 2] Japanese Patent Publication No. 2022-10591 Summary of the Invention [Problem to be solved by the invention]

[0004] Such suspension bushings are generally required to have different spring characteristics in multiple directions, and may require, for example, stiff spring characteristics in the direction perpendicular to the axis to improve driving stability, and soft spring characteristics in the torsional and twisting directions to improve ride comfort. To achieve these spring characteristics, structures such as those described in Patent Documents 1 and 2, in which a bulge portion that bulges outward in the axially middle portion of the inner shaft member, or a tapered portion that narrows in diameter inward in the axial end portion of the outer tubular member, are employed.

[0005] Furthermore, Patent Document 2 also employs a structure in which a hard intermediate member is provided radially between the inner shaft member and the outer cylindrical member, but these suspension bushings still have room for improvement in order to more stably achieve the required spring characteristics.

[0006] The problem to be solved by the present invention is to provide a new vibration-damping bushing and a method for manufacturing a vibration-damping bushing that can achieve both hard spring characteristics in the direction perpendicular to the axis and soft spring characteristics in the torsional and prying directions in a more stable manner. [Means for solving the problem]

[0007] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0008] In the first aspect, in a vibration-damping bushing in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, the inner shaft member is provided with a large-diameter bulge portion in the axial middle portion, while a cylindrical interring is disposed radially between the inner shaft member and the outer cylindrical member, and the main rubber elastic body is composed of an inner layer rubber elastic body located between the interring and the inner shaft member, and an outer layer rubber elastic body located between the interring and the outer cylindrical member, and at both axial ends of the interring, there are provided inter-slope portions that are tapered inward and have a smaller diameter toward the axial outward, and at both axial ends of the outer cylindrical member The inner layer rubber elastic body has outer circumferential surfaces at both axial ends thereof directly fixed to the interring, and both axial ends thereof are compressed and deformed in the radial direction by the inner slanted portions. The inner layer rubber elastic body has outer circumferential surfaces at both axial ends thereof directly fixed to the outer cylindrical member, and both axial ends thereof are compressed and deformed in the radial direction by the outer slanted portions.

[0009] According to this aspect of the vibration-damping bushing, inner inclined portions are provided at both axial ends of the interring, and outer inclined portions are provided at both axial ends of the outer tubular member. Therefore, when the vibration-damping bushing is mounted on a vehicle, in its initial state before an external force is applied, both axial ends of the inner rubber elastic body and the outer rubber elastic body are radially pre-compressed by the inner inclined portions and the outer inclined portions. As a result, when an external force is applied to the vibration-damping bushing in the direction perpendicular to the axis, axial outward deformation at both axial ends of the inner rubber elastic body and the outer rubber elastic body is somewhat suppressed, thereby exhibiting stiff spring characteristics.

[0010] By providing each inner inclined portion and each outer inclined portion in this manner, hard spring characteristics are exhibited in the direction perpendicular to the axis, which makes it possible to make the outer diameter dimension of the bulge portion provided in the axially middle part of the inner axial member relatively small, and by ensuring sufficient rubber volume of the inner layer rubber elastic body, soft spring characteristics can be exhibited in the torsional and prying directions.

[0011] The second aspect is a vibration-damping bushing described in the first aspect, in which the axial length dimension of the interring is greater than the axial length dimension of the outer tubular member, and the axial length dimension of the inner layer rubber elastic body is greater than the axial length dimension of the outer layer rubber elastic body.

[0012] For example, if the inner and outer rubber elastic layers are to exhibit similar spring characteristics, it is preferable to have the rubber volumes of the inner and outer rubber elastic layers close to each other. However, because the inner rubber elastic layer has a bulge on its inner periphery, the radial dimension of the inner rubber elastic layer tends to be smaller than that of the outer rubber elastic layer. However, with this vibration-damping bushing, the axial length of the inner rubber elastic layer is made larger than that of the outer rubber elastic layer, thereby making the rubber volumes closer to each other. Furthermore, by making the axial length of the interring larger than that of the outer tubular member, both axial ends of the inner rubber elastic layer, which has a relatively large axial length, can be stably pre-compressed by the interring inclined portion, thereby more reliably exhibiting stiff spring characteristics in the axis-perpendicular direction.

[0013] In a third aspect, in the vibration-damping bushing described in the first or second aspect, the entire axial end surfaces of the inner layer rubber elastic body and the outer layer rubber elastic body are free surfaces between the interring and the inner axial member or between the interring and the outer tubular member.

[0014] With this type of vibration-damping bushing, when an external force is applied in the direction perpendicular to the axis or in the torsional or prying direction, the inner layer rubber elastic body and the outer layer rubber elastic body can each deform stably, and the desired spring characteristics can be more reliably exhibited.

[0015] The fourth aspect is any one of the first to third aspects, wherein the compressive deformation rate of both axial end portions of the inner layer rubber elastic body or the outer layer rubber elastic body due to the inter inclined portion and the outer inclined portion is greater than the compressive deformation rate of the axial central portion of the inner layer rubber elastic body or the outer layer rubber elastic body.

[0016] With this type of vibration-damping bushing, each inter inclined portion and each outer inclined portion can ensure sufficient pre-compression at both axial ends of the inner layer rubber elastic body and the outer layer rubber elastic body, thereby more reliably achieving both hard spring characteristics in the direction perpendicular to the axis and soft spring characteristics in the torsional and prying directions.

[0017] A fifth aspect is any one of the first to fourth aspects, wherein the inner inclined portion is positioned axially outward of the outer inclined portion over its entire length.

[0018] According to this embodiment of the vibration-damping bushing, each inner inclined portion and each outer inclined portion are arranged in a position where they do not overlap in the axial direction along their respective entire lengths. Therefore, for example, when the inner inclined portion and the outer inclined portion are formed by bending, each inner inclined portion and each outer inclined portion can be formed simultaneously at both axial ends of the inner ring and the outer cylindrical member during the bending process, thereby improving the manufacturing efficiency of the vibration-damping bushing.

[0019] The sixth aspect is any one of the first to fifth aspects, wherein the axial end surfaces of the inner layer rubber elastic body and the outer layer rubber elastic body are undercut by the inter inclined portion and the outer inclined portion.

[0020] For example, if the axial end faces of the inner layer rubber elastic body and the outer layer rubber elastic body are not undercut, the inter inclined portion and the outer inclined portion cannot be formed with a large diameter reduction toward the inner circumference. However, by forming the axial end faces of the inner layer rubber elastic body and the outer layer rubber elastic body with an undercut shape, as in the vibration-damping bushing of this embodiment, the inter inclined portion and the outer inclined portion can be formed with a relatively large diameter reduction toward the inner circumference, and stable pre-compression can be achieved at both axial ends of the inner layer rubber elastic body and the outer layer rubber elastic body.

[0021] The seventh aspect is any one of the first to sixth aspects, wherein the difference between the inclination angle of the inner inclined portion toward the inner circumference and the inclination angle of the outer inclined portion toward the inner circumference is set within a range of ±5°.

[0022] With this type of vibration-damping bushing, it is possible, for example, to set the inclination angle toward the inner circumference of each inner inclined portion different from the inclination angle toward the inner circumference of each outer inclined portion, and by appropriately setting the inclination angle of each inner inclined portion and each outer inclined portion according to the required spring characteristics, it is possible to tune the spring characteristics of the inner layer rubber elastic body and the outer layer rubber elastic body.

[0023] The eighth aspect is any one of the first to seventh aspects, wherein the minimum radial thickness dimension at the axial center portion of the inner layer rubber elastic body is smaller than the radial thickness dimension at the axial center portion of the outer layer rubber elastic body.

[0024] According to this embodiment of the vibration-damping bushing, for example, by combining it with the second embodiment, it is possible to provide a large-diameter bulge portion in the axially middle portion of the inner shaft member while bringing the rubber volumes of the inner layer rubber elastic body and the outer layer rubber elastic body closer to each other, thereby making it possible to set the spring characteristics of the inner layer rubber elastic body and the outer layer rubber elastic body to be close to each other.

[0025] A ninth aspect is any one of the first to eighth aspects, wherein both axial ends of the main rubber elastic body are bonded to the inter-inclined portion of the interring, and the diameter reduction rate at the bonding surface with the main rubber elastic body at the inter-inclined portion is 5% or less.

[0026] By providing the inter inclined portion, both axial ends of the interring are reduced in diameter toward the inner circumference, but as in the vibration-damping bushing of this embodiment, by setting the reduction rate at the adhesive surface between the inter inclined portion of the interring and the main rubber elastic body to 5% or less, the main rubber elastic body can be effectively prevented from peeling off from the inter inclined portion.

[0027] A tenth aspect is any one of the first to ninth aspects, wherein both axial end surfaces of the inner layer rubber elastic body and the outer layer rubber elastic body have groove-shaped recesses extending in the circumferential direction, and the axial length dimension of the bulge portion of the inner axial member is smaller than the axial length dimension between the bottoms of the recesses in the inner layer rubber elastic body and larger than the axial length dimension between the bottoms of the recesses in the outer layer rubber elastic body.

[0028] According to this vibration-damping bushing, the outer diameter of the bulge is relatively small while the axial length is relatively large, thereby ensuring a sufficient volume for the bulge and allowing the rubber volume and spring characteristics of the inner layer rubber elastic body located radially between the inner shaft member and the interring to be appropriately set. Furthermore, by providing recesses on both axial end surfaces of the inner layer rubber elastic body and the outer layer rubber elastic body, the rubber volume and spring characteristics of the inner layer rubber elastic body and the outer layer rubber elastic body can be appropriately set while ensuring free surfaces of these inner layer rubber elastic body and outer layer rubber elastic body.

[0029] In an eleventh aspect, in a vibration-damping bushing in which an inner axial member and an outer cylindrical member are connected by a main rubber elastic body, the inner axial member is provided with a large-diameter bulge portion located in the axial middle, while a cylindrical interring is arranged radially between the inner axial member and the outer cylindrical member, and the main rubber elastic body is composed of an inner layer rubber elastic body located between the interring and the inner axial member, and an outer layer rubber elastic body located between the interring and the outer cylindrical member, and the outer peripheral surfaces of both axial end portions of the inner layer rubber elastic body and the outer layer rubber elastic body are fixed directly to the interring or the outer cylindrical member, and both axial end portions of the interring are provided with inter inclined portions that taper inward and decrease in diameter axially outward, so that radial pre-compression is applied to both axial end portions of the inner layer rubber elastic body, and the outer cylindrical member is reduced in diameter so that radial pre-compression is applied to the entire axial length of the outer layer rubber elastic body.

[0030] In this vibration-damping bushing, the inter-inclined portions apply radial pre-compression to both axial ends of the inner rubber elastic body, and the outer rubber elastic body is also pre-compressed radially along its entire axial length, allowing the inner and outer rubber elastic bodies to exhibit stiff spring characteristics in response to inputs in the direction perpendicular to the axis. This also allows the outer diameter of the bulge portion to be relatively small, allowing the inner and outer rubber elastic bodies to exhibit soft spring characteristics in response to inputs in the torsional and prying directions.

[0031] A twelfth aspect is a method for manufacturing a vibration-damping bushing described in any one of the first to tenth aspects, in which, after molding the inner layer rubber elastic body and the outer layer rubber elastic body, bending is simultaneously performed on the interring arranged on the outer peripheral surface of the inner layer rubber elastic body and the outer tubular member arranged on the outer peripheral surface of the outer layer rubber elastic body to form the inter inclined portion and the outer inclined portion.

[0032] According to the manufacturing method of the vibration-isolating bushing of this aspect, each inner inclined portion and each outer inclined portion can be formed in the same bending process, thereby improving the manufacturing efficiency of the vibration-isolating bushing. [Effects of the Invention]

[0033] According to the present invention, it is possible to provide a vibration-isolating bushing that can achieve both hard spring characteristics in the direction perpendicular to the axis and soft spring characteristics in the torsional and prying directions.

[0034] Furthermore, according to the method of the present invention, the above vibration-isolating bushing can be manufactured efficiently. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a front view showing a vibration-isolating bushing according to an embodiment of the present invention; [Figure 2] II-II cross section in Figure 1 [Figure 3] FIG. 2 is a front view showing the vibration-isolating bushing shown in FIG. 1 as an integrally molded product before the formation of the inner inclined portions and the outer inclined portions. [Figure 4] IV-IV cross section in Figure 3 DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0037] 1 and 2 show a suspension bushing 10, which is one embodiment of a vibration-damping bushing according to the present invention. The suspension bushing 10 has a structure in which an inner shaft member 12 and an outer cylindrical member 14 are interconnected by a main rubber elastic body 16. In the following description, as a general rule, the up-down direction refers to the up-down direction in Fig. 1, and the front-rear direction refers to the left-right direction in Fig. 2, which is the direction of the central axis of the bushing.

[0038] The inner shaft member 12 is a hard member made of a metal such as iron or an aluminum alloy. The inner shaft member 12 has a relatively thick, small-diameter, and generally cylindrical shape overall. The inner shaft member 12 has both axial end portions extending straight, and a large-diameter bulge portion 18 is provided in an axially intermediate portion (in the present embodiment, the central portion) thereof. This makes the outer diameter of the axially intermediate portion of the inner shaft member 12 larger than that of both axial end portions. In the present embodiment, the bulge portion 18 is formed in an annular shape over the entire circumferential direction. The bulge portion 18 has a predetermined axial length Lb (see FIG. 2). The axial end portions of the bulge portion 18 are portions that begin to bulge outward from both axial end portions that extend straight. Such an inner shaft member 12 can be manufactured by, for example, casting.

[0039] The outer cylindrical member 14 is a hard member made of a metal such as iron or an aluminum alloy. The outer cylindrical member 14 has a generally cylindrical shape with a relatively thin wall and a large diameter. The axially central portion of the outer cylindrical member 14 is an outer straight portion 20 that extends straight with generally constant outer and inner diameters, and outer inclined portions 22 that taper inward and outward in the axial direction are provided at both axial ends. The outer cylindrical member 14 provided with each outer inclined portion 22 has a predetermined axial length Lo (see FIG. 2). Each outer inclined portion 22 has a predetermined inclination angle θo (see FIG. 2) toward the inner circumference with respect to the outer straight portion 20 that extends straight in the axial direction.

[0040] The inner shaft member 12 and the outer cylindrical member 14 are coaxially arranged and elastically connected by a main rubber elastic body 16. The main rubber elastic body 16 is generally cylindrical overall, with its inner circumferential surface fixed to the outer circumferential surface of the inner shaft member 12 and its outer circumferential surface fixed to the inner circumferential surface of the outer cylindrical member 14. A cylindrical interring 24 is disposed radially between the inner shaft member 12 and the outer cylindrical member 14. This divides the main rubber elastic body 16 into inner and outer circumferential sides of the interring 24. In other words, the main rubber elastic body 16 is composed of an inner layer rubber elastic body 26 located between the interring 24 and the inner shaft member 12, and an outer layer rubber elastic body 28 located between the interring 24 and the outer cylindrical member 14.

[0041] In other words, the inner layer rubber elastic body 26 has a generally cylindrical shape overall, with its inner circumferential surface fixed to the outer circumferential surface of the inner shaft member 12 and its outer circumferential surface fixed to the inner circumferential surface of the interring 24. In this embodiment, the inner and outer circumferential surfaces of the inner layer rubber elastic body 26 are fixed over substantially the entire surfaces to the outer circumferential surface of the inner shaft member 12 and the inner circumferential surface of the interring 24, respectively. The axial length dimension of the inner layer rubber elastic body 26 at its inner circumferential end is greater than the axial length dimension of its outer circumferential end.

[0042] More specifically, the axially outer end of the inner peripheral end of the inner layer rubber elastic body 26 is located axially outward of the bulge portion 18 of the inner shaft member 12 and extends straight to both axial ends of the inner shaft member 12. Furthermore, the axially outer end of the inner layer rubber elastic body 26 is located axially outward of an inter-straight portion 34 (described later) provided in the axially intermediate portion of the inter-ring 24 and extends to inter-inclined portions 36 provided at both axial ends of the inter-ring 24. As a result, both axial end surfaces of the inner layer rubber elastic body 26 gradually or stepwise incline axially inward as they approach the outer periphery. These entire axial end surfaces of the inner layer rubber elastic body 26 are free surfaces, meaning that their deformation is not restricted by, for example, another member being fixed between the inner shaft member 12 and the inter-ring 24.

[0043] The inner rubber elastic body 26 has inner circumferential recesses 30 formed at both axial end surfaces thereof as groove-like recesses that open axially outward and extend circumferentially. In this embodiment, each inner circumferential recess 30 is formed as an annular groove that is continuous over the entire circumferential circumference. In particular, in this embodiment, the axial length dimension Ni (see FIG. 2 ) between the bottoms of the inner circumferential recesses 30 in the inner rubber elastic body 26 is set to be greater than the axial length dimension Lb of the bulge portion 18. Note that the inner and outer circumferential surfaces of the inner rubber elastic body 26 are secured to the inner shaft member 12 and the interring 24 with large axial length dimensions, and the substantial axial length dimension of the inner rubber elastic body 26 is understood to be the axial length dimension Ni between the bottoms of the inner circumferential recesses 30.

[0044] Furthermore, the inner axial member 12, located on the inner peripheral side of the inner layer rubber elastic body 26, has a bulge portion 18 in its axially intermediate portion (in this embodiment, its central portion) that bulges outward toward the outer periphery, so that the radial thickness of the inner layer rubber elastic body 26 is smaller in the axially intermediate portion than in both axial end portions. The inner layer rubber elastic body 26 has a minimum radial thickness Ti (see FIG. 2) in its axially intermediate portion.

[0045] The outer layer rubber elastic body 28 has a generally cylindrical shape overall, with its inner peripheral surface fixed to the outer peripheral surface of the interring 24 and its outer peripheral surface fixed to the inner peripheral surface of the outer cylindrical member 14. In this embodiment, the inner and outer peripheral surfaces of the outer layer rubber elastic body 28 are fixed over substantially the entire surfaces to the outer peripheral surface of the interring 24 and the inner peripheral surface of the outer cylindrical member 14, respectively. The axial length dimension of the outer layer rubber elastic body 28 at its inner peripheral end is greater than the axial length dimension of its outer peripheral end.

[0046] More specifically, the axially outer end of the inner peripheral end of the outer layer rubber elastic body 28 is located axially outward from an inter straight portion 34 (described later) provided in the axially intermediate portion of the interring 24, and extends to inter inclined portions 36 provided at both axial ends of the interring 24. Furthermore, the axially outer end of the outer peripheral end of the outer layer rubber elastic body 28 is located axially outward from the outer straight portion 20 of the outer tubular member 14, and extends to the outer inclined portions 22 that incline inward. As a result, both axial end surfaces of the outer layer rubber elastic body 28 gradually or stepwise incline axially inward as they approach the outer periphery. These entire axial end surfaces of the outer layer rubber elastic body 28 are free surfaces, meaning that their deformation is not restricted by, for example, another member being fixed between the interring 24 and the outer tubular member 14.

[0047] The outer rubber elastic body 28 has, at both axial end surfaces thereof, outer peripheral recesses 32, which are groove-like recesses that open axially outward and extend in the circumferential direction. In this embodiment, each outer peripheral recess 32 is formed as a continuous annular groove extending around the entire circumferential direction. In particular, in this embodiment, the axial length dimension No between the bottoms of the outer peripheral recesses 32 in the outer rubber elastic body 28 (see FIG. 2 ) is set smaller than the axial length dimension Lb of the bulge portion 18. Note that the inner and outer peripheral surfaces of the outer rubber elastic body 28 are secured to the interring 24 and the outer tubular member 14 with large axial length dimensions, and the substantial axial length dimension of the outer rubber elastic body 28 is understood to be the axial length dimension No between the bottoms of the outer peripheral recesses 32. Therefore, in this embodiment, the axial length dimension Ni of the inner rubber elastic body 26 is set larger than the axial length dimension No of the outer rubber elastic body 28.

[0048] Furthermore, since the axially intermediate portion of the outer rubber elastic body 28 is sandwiched between the inter straight portion 34 and the outer straight portion 20, which both extend straight in the axial direction, the radial thickness dimension To (see FIG. 2) of the axially intermediate portion is substantially constant. In this embodiment, the radial thickness dimension To of the outer rubber elastic body 28 at the axially central portion is set larger than the minimum radial thickness dimension Ti of the inner rubber elastic body 26 at the axially central portion.

[0049] The inter-ring 24 is a hard member made of metal, synthetic resin, or the like. The inter-ring 24 of this embodiment has a generally cylindrical shape overall and is thinner than the outer cylindrical member 14. The axial central portion of the inter-ring 24 is an inter-straight portion 34 that extends straight with generally constant outer and inner diameters, and both axial ends are provided with inter-inclined portions 36 that taper inward and decrease in diameter axially outward. In other words, the axial central portion of the inter-ring 24, excluding the inter-inclined portions 36 at both axial ends, is a straight cylindrical shape.

[0050] The inter-ring 24 provided with each inter-inclined portion 36 has a predetermined axial length Li (see FIG. 2). The axial length Li of the inter-ring 24 is greater than the axial length Lo of the outer tubular member 14. Each inter-inclined portion 36 also has a predetermined inclination angle θi (see FIG. 2) toward the inner periphery with respect to the inter-straight portion 34, which extends straight in the axial direction. The difference between the inclination angle θi toward the inner periphery of each inter-inclined portion 36 and the inclination angle θo toward the inner periphery of each outer inclined portion 22 is preferably set within a range of ±5°. If the difference between these inclination angles θi and θo is outside the ±5° range (i.e., greater than 5° or less than −5°), the difference between these inclination angles becomes too large, which may result in a large difference in spring characteristics between the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28.

[0051] In particular, the inter inclined portions 36 are provided axially outward from the outer cylindrical member 14. That is, the inter inclined portions 36 are located axially outward from the outer inclined portions 22 provided at both axial ends of the outer cylindrical member 14 over their entire lengths.

[0052] Here, the main rubber elastic body 16 of this embodiment is formed as an integrally vulcanization-molded product 38 including an inner axial member 12, an outer tubular member 14', and an interring 24' as shown in Figures 3 and 4. That is, after the inner axial member 12, the outer tubular member 14', and the interring 24' are set in the molding cavity of the main rubber elastic body 16, the material of the main rubber elastic body 16 is injected and molded, thereby obtaining the integrally vulcanization-molded product 38 at the same time as the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28 are formed.

[0053] 3 and 4, when the integrally vulcanization-molded product 38 is formed, the outer tubular member 14' and the inter-ring 24' do not have the outer inclined portion 22 and the inter-ring 24', respectively, and the outer tubular member 14' and the inter-ring 24' each have a shape that extends straight in the axial direction. Furthermore, inner peripheral recesses 30 are formed in both axial end faces of the inner layer rubber elastic body 26, and outer peripheral recesses 32 are formed in both axial end faces of the outer layer rubber elastic body 28. Then, in this integrally vulcanization-molded product 38, the outer inclined portion 22 is formed by bending both axial end faces of the outer tubular member 14', and the inter-ring 24' is bent to form the inter-ring 36, thereby forming the suspension bushing 10 of this embodiment.

[0054] As a pre-treatment for adhesion before vulcanization molding of the integrally vulcanization-molded product 38, for example, in addition to the outer peripheral surface of the interring 24', a chemical conversion coating may be applied to the inner peripheral surface of the interring 24', the outer peripheral surface of the inner axial member 12, the inner peripheral surface of the outer tubular member 14', etc. By forming the integrally vulcanization-molded product 38 in this manner, the outer peripheral surface of the inner layer rubber elastic body 26 is directly fixed to the interring 24' over the entire axial length, including both axial ends, and the outer peripheral surface of the outer layer rubber elastic body 28 is directly fixed to the outer tubular member 14' over the entire axial length, including both axial ends.

[0055] In particular, in this embodiment, since each inter inclined portion 36 is located axially outward of each outer inclined portion 22 along its entire length, after the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28 are molded (after the integral vulcanization molded product 38 is formed), each inter inclined portion 36 and each outer inclined portion 22 can be formed by simultaneously bending the interring 24' arranged on the outer peripheral surface of the inner layer rubber elastic body 26 and the outer tubular member 14' arranged on the outer peripheral surface of the outer layer rubber elastic body 28.

[0056] This bending is achieved by a diameter-reducing process such as a known eight-way drawing or sixteen-way drawing. In this embodiment, the above-mentioned diameter-reducing process is performed on both axial ends of the inter-ring 24' and also on the entire axial length of the outer cylindrical member 14', so that the outer diameter dimension of the outer cylindrical member 14' before diameter reduction is φα (see FIG. 3), whereas the outer diameter dimension of the outer cylindrical member 14 after diameter reduction (the outer diameter dimension of the outer straight portion 20) is φβ (see FIG. 1), which is smaller than φα.

[0057] In the suspension bushing 10 thus formed, the outer peripheral end of the inner rubber elastic body 26 has an axial length extending to each of the inter-inclined portions 36. Therefore, by forming each of the inter-inclined portions 36 at both axial ends of the inter-ring 24', both axial ends of the inner rubber elastic body 26 are radially compressed and pre-compressed. Similarly, the outer peripheral end of the outer rubber elastic body 28 has an axial length extending to each of the outer inclined portions 22. Therefore, by forming each of the outer inclined portions 22 at both axial ends of the outer tubular member 14', both axial ends of the outer rubber elastic body 28 are radially compressed and pre-compressed. Furthermore, by compressing and deforming both axial ends of the inner rubber elastic body 26 and the outer rubber elastic body 28 radially, both axial ends bulge outward in the axial direction. Therefore, when the suspension bushing 10 is completed, the depths of the inner peripheral recesses 30 and the outer peripheral recesses 32 are smaller than the state shown in FIGS. 3 and 4 before the radially contracting deformation.

[0058] Here, since the outer cylindrical member 14' is subjected to a diameter reduction process along its entire axial length, the outer rubber elastic body 28 is radially compressed along substantially its entire axial length, resulting in a pre-compressed state. Pre-compression may also be applied to the inner rubber elastic body 26 along substantially its entire axial length. In particular, the axial end portions of the interring 24 and the outer cylindrical member 14 are reduced in diameter relative to the axial center portion to form the inter inclined portions 36 and the outer inclined portions 22. The compressive deformation rate of the axial end portions of the inner rubber elastic body 26 due to the inter inclined portions 36 is preferably greater than the compressive deformation rate of the axial center portion of the inner rubber elastic body 26. Similarly, the compressive deformation rate of the axial end portions of the outer rubber elastic body 28 due to the outer inclined portions 22 is preferably greater than the compressive deformation rate of the axial center portion of the outer rubber elastic body 28. The compressive deformation rate can be calculated as the ratio of the change in radial thickness due to the diameter reduction process to the radial thickness before the diameter reduction process.

[0059] The diameter reduction rate of each inter inclined portion 36 is preferably 5% or less. Specifically, the diameter reduction rate of each inter inclined portion 36 at the bonding surface between the main rubber elastic body 16 (the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28) and the inter straight portion 34 is preferably 5% or less. In this embodiment, since the entire inner peripheral surface of the outer layer rubber elastic body 28 is fixed (bonded) to the outer peripheral surface of the interring 24, when the outer diameter dimension of the inter straight portion 34 at the interring 24 is φγ (see FIG. 2) and the outer diameter dimension of the outer layer rubber elastic body 28 at the axial end portion at each inter inclined portion 36 is φδ (see FIG. 2), it is preferable that (φγ - φδ) ≦ (φγ × 0.05). The same applies to the bonding portion of the inner layer rubber elastic body 26. If the diameter reduction rate in each inter-inclined portion 36 is greater than 5%, it may become difficult to stably ensure the adhesive strength between the interring 24 and the main rubber elastic body 16 (inner layer rubber elastic body 26 and outer layer rubber elastic body 28) in the inter-inclined portion 36.

[0060] 2, by providing each inter inclined portion 36 at both axial ends of the inter ring 24, the outer peripheral end of the inner peripheral recess 30 and the inner peripheral end of each inter inclined portion 36 overlap in axial projection. As a result, each inter inclined portion 36 forms an undercut shape in the axial direction at both axial end faces of the inner layer rubber elastic body 26. Similarly, by providing each outer inclined portion 22 at both axial end faces of the outer tubular member 14, the outer peripheral end of the outer peripheral recess 32 and the inner peripheral end of each outer inclined portion 22 overlap in axial projection. As a result, each outer inclined portion 22 forms an undercut shape in the axial direction at both axial end faces of the outer layer rubber elastic body 28.

[0061] The suspension bushing 10 manufactured in this manner is mounted to a vehicle, for example, by attaching the inner shaft member 12 to a suspension arm (not shown) and the outer tubular member 14 to a subframe (not shown). The main rubber elastic body 16 then exerts a vibration-damping effect by damping and insulating vibrations against vibrations input from the wheel due to unevenness of the ground or the like.

[0062] According to the suspension bushing 10 of this embodiment having the above-described structure, when vibration is input to the suspension bushing 10 in the direction perpendicular to the axis, the inner rubber elastic layer 26 and the outer rubber elastic layer 28 are compressed and deformed in the radial direction, but because the inner inclined portions 36 and the outer inclined portions 22, which are bent inward at both axial ends of the interring 24 and the outer tubular member 14, are located axially outward of the inner rubber elastic layer 26 and the outer rubber elastic layer 28, outward axial expansion deformation at both axial ends of the inner rubber elastic layer 26 and the outer rubber elastic layer 28 is suppressed, and relatively stiff spring characteristics are exhibited, thereby improving the running stability of the vehicle.

[0063] In particular, by employing the inter inclined portion 36 in addition to the outer inclined portion 22 and exerting a deformation suppressing effect on both axial ends of the inner rubber elastic body 26, which has a relatively large radial dimension, it is possible to achieve nonlinear spring characteristics even at low load levels in the axis-perpendicular direction. Therefore, it is possible to achieve a high level of both insulating performance against low-level vibrations and cushioning displacement suppression performance against high-level vibration inputs.

[0064] Furthermore, to achieve stiff spring characteristics against inputs perpendicular to the axis, it is conceivable to increase the outer diameter of the bulge portion of the inner shaft member and reduce the radial dimension of the main rubber elastic body. However, since stiff spring characteristics are achieved by providing the inter inclined portions 36 and the outer inclined portions 22 as described above, in this embodiment, the outer diameter of the bulge portion 18 can be made relatively small, thereby ensuring a relatively large radial dimension for the main rubber elastic body 16 (particularly the inner layer rubber elastic body 26). This allows the rubber volume of the main rubber elastic body 16 to be relatively large, resulting in soft spring characteristics against inputs in the torsional and prying directions. As a result, the ride comfort of the vehicle is improved.

[0065] The axial length dimension Li of the interring 24 is made larger than the axial length dimension Lo of the outer tubular member 14, and the axial length dimension Ni of the inner layer rubber elastic body 26 is made larger than the axial length dimension No of the outer layer rubber elastic body 28. In addition, the minimum radial thickness dimension Ti at the axial center portion of the inner layer rubber elastic body 26 is made smaller than the radial thickness dimension To at the axial center portion of the outer layer rubber elastic body 28. This makes it possible to make the rubber volumes of the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28 approximately equal, allowing the main rubber elastic body 16 to stably exhibit the desired spring characteristics.

[0066] The entire axial end faces of both the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28 are free surfaces between the interring 24 and the inner axial member 12, or between the interring 24 and the outer tubular member 14. This allows stable deformation of both axial end faces of the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28 with a large free surface area, achieving both hard spring characteristics in the axis-perpendicular direction and soft spring characteristics in the torsional and prying directions with excellent durability.

[0067] In this embodiment, the compressive deformation rate of both axial end portions of the inner layer rubber elastic body 26 or the outer layer rubber elastic body 28 due to each inter inclined portion 36 and each outer inclined portion 22 is set to be larger than the compressive deformation rate of the axial center portion of the inner layer rubber elastic body 26 or the outer layer rubber elastic body 28. By ensuring a relatively large compressive deformation rate (pre-compression rate) at both axial end portions of the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28, it is possible to achieve both the above-mentioned hard spring characteristics in the axis-perpendicular direction and soft spring characteristics in the torsional and prying directions.

[0068] Each of the inter inclined portions 36 is located axially outward of each of the outer inclined portions 22 over its entire length. Therefore, when each of the inter inclined portions 36 and each of the outer inclined portions 22 is formed by bending, as in this embodiment, each of the inter inclined portions 36 and each of the outer inclined portions 22 can be formed by the same bending process. Therefore, there is no need to use an interring or outer cylindrical member whose both axial ends are already reduced in diameter when forming the integrally vulcanization molded product 38, which also reduces costs.

[0069] Both axial end surfaces of the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28 are undercut by the inter inclined portions 36 and the outer inclined portions 22. In other words, if both axial end surfaces were not undercut, both axial end surfaces of the inner layer rubber elastic body and the outer layer rubber elastic body would not be covered from the axial outside by the inter inclined portions 36 and the outer inclined portions 22, and there is a risk that the desired spring characteristics would not be exhibited. However, by forming both axial end surfaces into an undercut shape, the desired spring characteristics can be stably exhibited. Furthermore, such an undercut shape is advantageous from the standpoint of protecting both axial end surfaces of the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28 from foreign objects such as flying stones and external heat.

[0070] The difference between the inclination angle θi of each inner inclined portion 36 toward the inner periphery and the inclination angle θo of each outer inclined portion 22 toward the inner periphery is set within a range of ±5°. This makes it possible to make the inclination angle θi of each inner inclined portion 36 toward the inner periphery and the inclination angle θo of each outer inclined portion 22 toward the inner periphery equal or different, enabling tuning according to desired spring characteristics.

[0071] In each inter-inclined portion 36, the diameter reduction rate at the bonding surface with the main rubber elastic body 16 (the inner layer rubber elastic body 26 and the outer layer rubber elastic body 28) is set to 5% or less. This makes it possible to prevent each inter-inclined portion 36 and the main rubber elastic body 16 fixed (bonded) to the inter-ring 24 from peeling off from each other when bending deformation occurs at both axial ends of the inter-ring 24.

[0072] Circumferentially extending inner and outer circumferential recesses 30 and 32 are provided on both axial end surfaces of the inner and outer rubber elastic bodies 26 and 28, and the axial length dimension Lb of the bulge portion 18 of the inner shaft member 12 is smaller than the axial length dimension Ni between the bottoms of the inner circumferential recesses 30 in the inner rubber elastic body 26 and larger than the axial length dimension No between the bottoms of the outer circumferential recesses 32 in the outer rubber elastic body 28. This makes it possible to ensure a certain level of volume for the bulge portion 18 while keeping the outer diameter dimension of the bulge portion 18 relatively small, thereby enabling the rubber volume of the inner rubber elastic body 26 to be appropriately set. In this way, by appropriately setting the outer diameter dimension and axial length dimension of the bulge portion 18, the spring characteristics of the inner and outer rubber elastic bodies 26 and 28 can be tuned.

[0073] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific descriptions.

[0074] For example, in the above embodiment, the inter inclined portions 36 are provided at both axial ends of the inter ring 24, and the outer inclined portions 22 are provided at both axial ends of the outer cylindrical member 14. However, this is not limiting, and in another aspect of the present invention, outer inclined portions may not be provided. That is, in a vibration-damping bushing according to another aspect of the present invention, the inter inclined portions 36 may be provided at both axial ends of the inter ring 24, and the inter inclined portions 36 may apply axial pre-compression to both axial ends of the inner rubber elastic body 26, while the outer cylindrical member 14 may be reduced in diameter, thereby applying radial pre-compression to the entire axial length of the outer rubber elastic body 28. Therefore, in a vibration-damping bushing according to another aspect of the present invention, the outer cylindrical member 14 may have a shape that extends straight over its entire axial length, as shown in FIGS.

[0075] The axial length dimensions of the bulge portion and interring of the inner shaft member, the outer cylindrical member, etc. are not limited; for example, the axial length of the outer cylindrical member may be greater than that of the interring. Similarly, the axial length dimensions of the inner rubber elastic body, the outer rubber elastic body, the distance between the bottoms of the inner peripheral recesses, the distance between the bottoms of the outer peripheral recesses, etc. are not limited; for example, the axial length of the outer rubber elastic body may be greater than that of the inner rubber elastic body. Furthermore, the radial width dimensions of the inner rubber elastic body and the outer rubber elastic body are not limited in any way. However, the inner peripheral recesses and / or outer peripheral recesses are not essential to the inner rubber elastic body and the outer rubber elastic body; they may be absent or may be provided intermittently in the circumferential direction.

[0076] In the above embodiment, when manufacturing the vibration-damping bushing (suspension bushing 10), the inner inclined portions 36 and the outer inclined portions 22 are formed by simultaneously bending both axial ends of the interring 24′ and the outer tubular member 14′. However, this is not a limitation. For example, the inner inclined portions and the outer inclined portions may be formed sequentially. In this case, the inner inclined portions and the outer inclined portions may be formed to overlap partially or entirely in the axial direction. While the outer inclined portions are formed by bending both axial ends of the outer tubular member after molding the outer rubber elastic body, this is not a limitation. For example, when forming an integrally vulcanization-molded product, an outer tubular member whose axial ends have already been bent to form the outer inclined portions may be set into the molding cavity of the main rubber elastic body. In other words, in another aspect of the present invention, the outer inclined portions may be formed before molding the outer rubber elastic body.

[0077] In the above embodiment, the axially outer end of the inner circumferential end of the outer rubber elastic body 28 reaches the axially intermediate portions of each inter-inclined portion 36, and the entire inner circumferential surface of the outer rubber elastic body 28 serves as the surface to be fixed (adhered) to the inter-ring 24. However, this is not limited to this embodiment. For example, the axially outer end of the inner circumferential end of the outer rubber elastic body may reach the axially outer ends of each inter-inclined portion. In this case, the entire surface of the outer rubber elastic body does not need to serve as the surface to be fixed (adhered) to the inter-ring. For example, as in the above embodiment, the surface to be fixed (adhered) may extend to the axially intermediate portions of each inter-inclined portion, and the portions axially outward from that may overlap each inter-inclined portion in a non-adhered state. Similarly, the entire outer circumferential surface of the inner rubber elastic body does not need to serve as the surface to be fixed (adhered) to the inter-ring. At the bonding surfaces (adhesion surfaces) between the inner rubber elastic layer and / or the outer rubber elastic layer and each inter inclined portion, the diameter reduction rate at each inter inclined portion is preferably 5% or less, but as described above, in the regions where the inner rubber elastic layer and / or the outer rubber elastic layer and each inter inclined portion are overlapped in a non-bonded state, the diameter reduction rate at each inter inclined portion may be greater than 5%. However, at the bonding surfaces (adhesion surfaces) between the inner rubber elastic layer and / or the outer rubber elastic layer and each inter inclined portion, the diameter reduction rate at each inter inclined portion is not limited to 5% or less and may be greater than 5%.

[0078] In the above embodiment, a suspension bushing 10 is described as an anti-vibration bushing according to the present invention, but this is merely an example and the invention may be applied to various anti-vibration bushings for automobiles, or various anti-vibration bushings for non-automotive uses. [Explanation of symbols]

[0079] 10 Suspension bushing (vibration-proof bushing) 12 Inner shaft member 14,14' Outer cylindrical member 16 Main body rubber elastic body 18 Bulge 20 Outer straight section 22 Outer inclined part 24,24' Interlocking 26 Inner layer rubber elastic body 28 Outer layer rubber elastic body 30 Inner recess (recess) 32 Outer circumferential recess (recess) 34 Interface section 36 Inter-slope section 38 Integral vulcanization molding Lb Axial length of the bulge Li Interring axial length dimension Lo Axial length dimension of outer cylindrical member Ni Axial length dimension of inner rubber elastic body (axial length dimension between the bottoms of the recesses) No. Axial length of outer rubber elastic body (axial length between the bottoms of the recesses) θi The angle of inclination of the inner inclined part θo: The angle of inclination of the outer inclined part toward the inner circumference

Claims

1. In a vibration-isolating bushing in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, The inner shaft member has a large-diameter bulge portion at an axially intermediate portion thereof, A cylindrical interring is disposed radially between the inner shaft member and the outer cylindrical member, and the main rubber elastic body is composed of an inner layer rubber elastic body positioned between the interring and the inner shaft member and an outer layer rubber elastic body positioned between the interring and the outer cylindrical member; The inter ring has an inclined portion at each end in the axial direction, the inclined portion being tapered inward and tapering outward in the axial direction, The outer cylindrical member is provided at both axial end portions thereof with outer inclined portions whose diameters are reduced toward the inner periphery and toward the axial outward direction, The central portion of the interring in the axial direction, excluding the inclined portions at both ends of the interring in the axial direction, is formed into a straight cylindrical shape, The outer peripheral surfaces of both axial ends of the inner rubber elastic body are directly fixed to the interrings, and both axial ends of the inner rubber elastic body are compressed and deformed in the radial direction by the interring inclined portions. The outer circumferential surfaces of both axial ends of the outer rubber elastic body are directly fixed to the outer cylindrical member, and both axial ends of the outer rubber elastic body are compressed and deformed in the radial direction by the outer inclined portion.

2. 2. A vibration-damping bushing as described in claim 1, wherein the axial length dimension of the interring is greater than the axial length dimension of the outer cylindrical member, and the axial length dimension of the inner layer rubber elastic body is greater than the axial length dimension of the outer layer rubber elastic body.

3. A vibration-damping bushing as described in claim 1 or 2, wherein the entire axial end surfaces of the inner layer rubber elastic body and the outer layer rubber elastic body are free surfaces between the interring and the inner axial member or between the interring and the outer tubular member.

4. A vibration-damping bushing as described in claim 1 or 2, wherein the compressive deformation rate of both axial ends of the inner layer rubber elastic body or the outer layer rubber elastic body due to the inter inclined portion and the outer inclined portion is greater than the compressive deformation rate of the axial central portion of the inner layer rubber elastic body or the outer layer rubber elastic body.

5. 3. The vibration-isolating bushing according to claim 1, wherein the inner inclined portion is positioned axially outward of the outer inclined portion over its entire length.

6. 3. The vibration-isolating bushing according to claim 1, wherein axial end faces of the inner rubber elastic body and the outer rubber elastic body are undercut by the inner inclined portion and the outer inclined portion.

7. 3. The vibration-isolating bushing according to claim 1, wherein the difference between the inclination angle of the inner inclined portion and the inclination angle of the outer inclined portion is set within a range of ±5°.

8. 3. A vibration-damping bushing according to claim 1, wherein the minimum radial thickness dimension at the axial center portion of the inner rubber elastic body is smaller than the radial thickness dimension at the axial center portion of the outer rubber elastic body.

9. the main rubber elastic body has both axial end portions bonded to the inter-inclined portion of the inter-ring, 3. The vibration-isolating bushing according to claim 1, wherein the diameter reduction rate of the inter-inclined portion at the bonding surface with the main rubber elastic body is 5% or less.

10. the inner rubber elastic body and the outer rubber elastic body have groove-like recesses extending in the circumferential direction at both axial end surfaces thereof; A vibration-damping bushing as described in claim 1 or 2, wherein the axial length dimension of the bulge portion of the inner shaft member is smaller than the axial length dimension between the bottoms of the recesses in the inner layer rubber elastic body and larger than the axial length dimension between the bottoms of the recesses in the outer layer rubber elastic body.

11. In a vibration-isolating bushing in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, The inner shaft member is provided with a large-diameter bulge portion located at an axially intermediate portion thereof, A cylindrical interring is disposed radially between the inner shaft member and the outer cylindrical member, and the main rubber elastic body is composed of an inner layer rubber elastic body positioned between the interring and the inner shaft member and an outer layer rubber elastic body positioned between the interring and the outer cylindrical member; the outer circumferential surfaces of both axial ends of the inner rubber elastic body and the outer rubber elastic body are directly fixed to the inter-ring or the outer cylindrical member, The inner ring has at its both axial ends inclined inner portions which are tapered inward and outward in diameter, and the inner ring has at its both axial ends inclined inner portions which apply radial precompression to both axial ends of the inner rubber elastic body. The outer cylindrical member is reduced in diameter, so that the outer rubber elastic body is pre-compressed in the radial direction over the entire axial length thereof.

12. When manufacturing the vibration-isolating bushing according to claim 1 or 2, A method for manufacturing a vibration-damping bushing in which, after molding the inner layer rubber elastic body and the outer layer rubber elastic body, the interring arranged on the outer peripheral surface of the inner layer rubber elastic body and the outer tubular member arranged on the outer peripheral surface of the outer layer rubber elastic body are simultaneously bent to form the inter inclined portion and the outer inclined portion.

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