Bushing, vibration isolation structure, and method for manufacturing vibration isolation structure

Abstract

Provided are a bushing, a vibration isolation structure, and a vibration isolation structure manufacturing method, with which it is possible to improve workability when joining a bushing to a rod-like member.　A bushing 1 includes: a bracket 2 having an outer cylinder 25; an inner cylinder 3; and a body rubber part 4 that connects the outer cylinder and the inner cylinder to each other. The inner cylinder is composed of a thermoplastic resin.

Description

Bush, vibration-proof structure, and vibration-proof structure manufacturing method

[0001] The present invention relates to a bushing, a vibration-isolating structure, and a method for manufacturing a vibration-isolating structure.

[0002] 2. Description of the Related Art Conventionally, there is a vibration-damping structure in which the inner peripheral surface of a cylindrical rubber elastic body in a bush is bonded to a rod-shaped member (such as a stabilizer bar) by adhesive (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-147408

[0004] However, in the conventional technology, there is room for improvement in the ease of joining the bush to the rod-shaped member (and ultimately in the manufacturability of the vibration-isolating structure).

[0005] An object of the present invention is to provide a bush, an anti-vibration structure, and a method for manufacturing an anti-vibration structure that can improve workability when joining a bush to a rod-shaped member.

[0006] [1] A bushing comprising a bracket portion having an outer tubular portion, an inner tubular portion, and a main rubber portion connecting the outer tubular portion and the inner tubular portion, wherein the inner tubular portion is made of a thermoplastic resin, thereby improving workability when joining the bushing to a rod-shaped member.

[0007] [2] The bushing according to [1], further comprising a pair of split assemblies, each of which comprises a split bracket member having a split outer tubular portion that forms part of the bracket portion and a circumferential portion of the outer tubular portion, a split inner tubular member that forms a circumferential portion of the inner tubular portion, and a split main body rubber member that forms a circumferential portion of the main body rubber portion and connects the split outer tubular portion of the split bracket member to the split inner tubular member. This further improves ease of installation when joining the bushing to a rod-shaped member.

[0008] [3] The bushing according to [1], wherein the inner cylindrical portion is welded to a rod-shaped member extending along the inner periphery of the inner cylindrical portion, thereby improving workability when joining the bushing to the rod-shaped member.

[0009] [4] A vibration-damping structure comprising the bushing according to any one of [1] to [3] and a rod-shaped member extending along the inner periphery of the inner cylindrical portion of the bushing, the inner cylindrical portion being welded to the rod-shaped member, thereby improving workability when joining the bushing to the rod-shaped member.

[0010] [5] The vibration-damping structure according to [4], wherein the outer peripheral surface of the rod-shaped member has a rough surface portion with a plurality of recesses, and the inner cylindrical portion is welded to the rough surface portion of the rod-shaped member. This makes it possible to more reliably join the inner cylindrical portion and the rod-shaped member.

[0011] [6] A method for manufacturing the vibration-damping structure according to [4] or [5], comprising: a bushing manufacturing step of manufacturing the bushing; and a rod-shaped member joining step of joining the inner cylindrical portion of the bushing by welding, with the rod-shaped member extending on the inner circumferential side of the inner cylindrical portion. This improves workability when joining the bushing to the rod-shaped member.

[0012] [7] The method for manufacturing a vibration-proof structure according to [6], wherein in the rod-shaped member joining step, a coil is disposed on the outer periphery of the rod-shaped member, and the rod-shaped member is heated by electromagnetic induction heating, thereby melting the inner circumferential surface of the inner cylindrical portion and fusing it to the rod-shaped member. This further improves workability when joining the bushing to the rod-shaped member.

[0013] According to the present invention, it is possible to provide a bush, an anti-vibration structure, and a method for manufacturing an anti-vibration structure that can improve workability when joining a bush to a rod-shaped member.

[0014] 1 is a schematic diagram for explaining a rod-shaped member arranging step in a method for manufacturing an anti-vibration structure according to a first embodiment of the present invention, and is an A-A cross-sectional view generally showing the bushing and anti-vibration structure according to the first embodiment of the present invention in a state before a rod-shaped member is arranged on the inner circumferential side of the bushing immediately before the rod-shaped member arranging step, taken along line A-A in FIG. 2 which is parallel to the axial direction. FIG. 2 is a schematic diagram for explaining a rod-shaped member arranging step in a method for manufacturing an anti-vibration structure according to a first embodiment of the present invention, and is a B-B cross-sectional view generally showing the bushing and anti-vibration structure according to the first embodiment of the present invention in the state shown in FIG. 1, taken along line B-B in FIG. 1 which is parallel to the axial direction. FIG. 3 is a schematic diagram for explaining a rod-shaped member arranging step in a method for manufacturing an anti-vibration structure according to a first embodiment of the present invention, and is a cross-sectional view generally showing the bushing and anti-vibration structure according to the first embodiment of the present invention in a state in which a rod-shaped member has been arranged on the inner circumferential side of the bushing immediately after the rod-shaped member arranging step, taken along the same cross-section as FIG. 8 is a schematic diagram for explaining an example of a rod-shaped member joining step in the method for manufacturing an anti-vibration structure according to the first embodiment of the present invention, and is an axial cross-sectional view, similar to that of FIG. 2, of the bushing and anti-vibration structure according to the first embodiment of the present invention during the rod-shaped member joining step. FIG. 9 is a schematic diagram for explaining another example of a rod-shaped member joining step in the method for manufacturing an anti-vibration structure according to the first embodiment of the present invention, and is an axial cross-sectional view, similar to that of FIG. 2, of the bushing and anti-vibration structure according to the first embodiment of the present invention during the rod-shaped member joining step. FIG. 10 is a schematic diagram for explaining a bracket part attachment step in the method for manufacturing an anti-vibration structure according to the first embodiment of the present invention, and is an axial cross-sectional view, similar to that of FIG. 1, of the bushing and anti-vibration structure according to the first embodiment of the present invention immediately after the bracket part attachment step. It is also a CC cross-sectional view, similar to that of FIG. 1, of the bushing and anti-vibration structure according to the first embodiment of the present invention, and is a CC cross-sectional view, similar to that of FIG. 8, and is a DD ... parallel to the axial direction, of the bushing and anti-vibration structure according to the first embodiment of the present invention. 7 is a top view schematically showing the bush and vibration-proof structure in the state shown in FIG. 6 when viewed in a direction from the first vertical side to the second vertical side. FIG.It is a bottom view schematically showing the state of the bush and the vibration isolation structure in the state of FIG. 6 when viewed in the direction from the second side in the vertical direction to the first side in the vertical direction. It is a schematic diagram for explaining the rod-shaped member arrangement step in the method for manufacturing a vibration isolation structure according to the second embodiment of the present invention, and is in a state before arranging the rod-shaped member on the inner peripheral side of the bush immediately before the rod-shaped member arrangement step. It is an E-E cross-sectional view schematically showing the bush and the vibration isolation structure according to the second embodiment of the present invention by a cross-section along the E-E line of FIG. 11 parallel to the axial straight direction. It is a schematic diagram for explaining the rod-shaped member arrangement step in the method for manufacturing a vibration isolation structure according to the second embodiment of the present invention, and is an F-F cross-sectional view schematically showing the bush and the vibration isolation structure according to the second embodiment of the present invention in the state of FIG. 10 by a cross-section along the F-F line of FIG. 10 parallel to the axial direction. It is a schematic diagram for explaining the rod-shaped member arrangement step in the method for manufacturing a vibration isolation structure according to the second embodiment of the present invention, and is an axial straight direction cross-sectional view schematically showing the bush and the vibration isolation structure according to the second embodiment of the present invention in a state where the rod-shaped member is arranged on the inner peripheral side of the bush immediately after the rod-shaped member arrangement step by a cross-section similar to that of FIG. 10. It is a schematic diagram for explaining an example of the rod-shaped member joining step in the method for manufacturing a vibration isolation structure according to the second embodiment of the present invention, and is an axial direction cross-sectional view schematically showing the vibration isolation structure according to the second embodiment of the present invention during the rod-shaped member joining step by a cross-section similar to that of FIG. 11. It is a schematic diagram for explaining another example of the rod-shaped member joining step in the method for manufacturing a vibration isolation structure according to the second embodiment of the present invention, and is an axial direction cross-sectional view schematically showing the bush and the vibration isolation structure according to the second embodiment of the present invention during the rod-shaped member joining step by a cross-section similar to that of FIG. 11. It is a schematic diagram for explaining the bracket portion mounting step in the method for manufacturing a vibration isolation structure according to the second embodiment of the present invention, and is an axial straight direction cross-sectional view schematically showing the bush and the vibration isolation structure according to the second embodiment of the present invention immediately after the bracket portion mounting step by a cross-section similar to that of FIG. 10, and is also a G-G cross-sectional view schematically showing by a cross-section along the G-G line of FIG. 16 parallel to the axial straight direction. It is an H-H cross-sectional view schematically showing the bush and the vibration isolation structure in the state of FIG. 15 by a cross-section along the H-H line of FIG. 15 parallel to the axial direction.FIG. 17 is an axial cross-sectional view similar to FIG. 16, showing a modified example of the bush and vibration-proof structure according to the second embodiment of the present invention.

[0015] The bushing, vibration-damping structure, and vibration-damping structure manufacturing method of the present invention are suitable for use in the connecting portion between a rod-shaped member in a vehicle (e.g., a torsion bar of the vehicle, particularly a stabilizer bar) and a vibration-receiving member (e.g., a part of the vehicle body).

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a bush, an anti-vibration structure, and a method for manufacturing an anti-vibration structure according to the present invention will be described with reference to the drawings.

[0017] FIGS. 1 to 9 are drawings for explaining a bushing, a vibration-proof structure, and a method for manufacturing a vibration-proof structure according to a first embodiment of the present invention, as well as modified examples thereof. The method for manufacturing a vibration-proof structure according to the first embodiment of the present invention is used to manufacture a vibration-proof structure S according to the first embodiment of the present invention, as illustrated in FIGS. 6 to 9. The vibration-proof structure S according to the first embodiment of the present invention includes a bushing 1 according to the first embodiment of the present invention and a rod-shaped member R. FIGS. 10 to 17 are drawings for explaining a bushing, a vibration-proof structure, and a method for manufacturing a vibration-proof structure according to a second embodiment of the present invention, as well as modified examples thereof. The method for manufacturing a vibration-proof structure according to the second embodiment of the present invention is used to manufacture a vibration-proof structure S according to the second embodiment of the present invention, as illustrated in the example of FIGS. 15 to 16 and the modified example of FIG. 17. The vibration-proof structure S according to the second embodiment of the present invention includes a bushing 1 according to the second embodiment of the present invention and a rod-shaped member R. The method for manufacturing a vibration-proof structure according to the second embodiment of the present invention, which will be described with reference to FIGS. 10 to 17, is basically the same as the method for manufacturing a vibration-proof structure according to the first embodiment of the present invention, as illustrated with reference to FIGS. 1 to 9, with the only difference being the configuration of the bushing 1 and the vibration-proof structure S to be manufactured.

[0018] For the sake of convenience, the first and second embodiments will be described in parallel below. Unless otherwise specified, the matters described below are matters that can be applied to each example (each embodiment and their modified examples) described in this specification.

[0019] In this specification, when describing the bush 1 and the vibration-proof structure S, for convenience, unless otherwise specified, the description will be made of the structure when no input is applied to the bush 1 or the vibration-proof structure S and the bush 1 or the vibration-proof structure S is in a stationary, normal state, as shown in each figure.

[0020] First, the basic configuration of the bush 1 and the vibration isolation structure S in the first and second embodiments will be described.

[0021] 6 to 9, 15 to 17, etc., the bushing 1 includes a bracket portion 2 having an outer cylindrical portion 25, an inner cylindrical portion 3, and a main rubber portion 4. The main rubber portion 4 connects the outer cylindrical portion 25 and the inner cylindrical portion 3 together.

[0022] The bushing 1 includes a pair of split assemblies 5. Each split assembly 5 includes a split bracket member 2D, a split inner tubular member 3D, and a split main body rubber member 4D. The split bracket member 2D forms part of the bracket portion 2. The split bracket member 2D has a split outer tubular member 25D that forms a circumferential portion of the outer tubular member 25. The split inner tubular member 3D forms a circumferential portion of the inner tubular member 3. The split inner tubular member 3D is located on the inner circumferential side of the split outer tubular member 25D. The split main body rubber member 4D forms a circumferential portion of the main body rubber member 4. The split main body rubber member 4D is located radially between the split outer tubular member 25D and the split inner tubular member 3D of the split bracket member 2D, connecting the split outer tubular member 25D and the split inner tubular member 3D. In this way, the bushing 1 is split into two split assemblies 5.

[0023] In this specification, one of the pair of split assemblies 5 is referred to as the "first split assembly 51," and the other of the pair of split assemblies 5 is referred to as the "second split assembly 52." Furthermore, the split bracket member 2D, split outer cylinder portion 25D, split inner cylinder member 3D, and split main body rubber member 4D of the first split assembly 51 are referred to as the first split bracket member 2D1, first split outer cylinder portion 25D1, first split inner cylinder member 3D1, and first split main body rubber member 4D1, respectively. Furthermore, the split bracket member 2D, split outer cylinder portion 25D, split inner cylinder member 3D, and split main body rubber member 4D of the second split assembly 52 are referred to as the second split bracket member 2D2, second split outer cylinder portion 25D2, second split inner cylinder member 3D2, and second split main body rubber member 4D2, respectively.

[0024] The bracket portion 2 is composed of a pair of split bracket members 2D (first split bracket member 2D1 and second split bracket member 2D2). The outer tube portion 25 of the bracket portion 2 is composed of a pair of split outer tube portions 25D (first split outer tube portion 25D1 and second split outer tube portion 25D2). The inner tube portion 3 is composed of a pair of split inner tube members 3D (first split inner tube member 3D1 and second split inner tube member 3D2). The main body rubber portion 4 is composed of a pair of split main body rubber members 4D (first split main body rubber member 4D1 and second split main body rubber member 4D2).

[0025] 1-2 and 10-11, each split assembly 5 is formed integrally by connecting a split bracket member 2D, a split inner cylinder member 3D, and a split main body rubber member 4D to each other. Before being joined to the rod-shaped member R, the pair of split assemblies 5 are separated from each other and are configured to be able to be assembled together (FIGS. 3, 6, 12, 15).

[0026] When the pair of split assemblies 5 are separated from each other (FIGS. 1 and 10), the central axes O25 of the split outer cylinder portions 25D and the central axes O3 of the split inner cylinder members 3D are separated from each other. Here, the central axis O25 of the split outer cylinder portion 25D corresponds to the central axis of an imaginary cylinder formed by extending the split outer cylinder portion 25D all around. Similarly, the central axis O3 of the split inner cylinder member 3D corresponds to the central axis of an imaginary cylinder formed by extending the split inner cylinder member 3D all around.

[0027] When a pair of split assemblies 5 are assembled in close contact with each other (hereinafter also referred to as the "closely assembled state") (FIGS. 6 and 15), the split outer tube portions 25D contact each other, forming a cylindrical outer tube portion 25; the split inner tube members 3D contact each other, forming a cylindrical inner tube portion 3; and the split main body rubber members 4D contact each other, forming a cylindrical main body rubber portion 4. At this time, the central axes O25 of the split outer tube portions 25D coincide with each other to form the central axis O25 of a single outer tube portion 25, and the central axes O3 of the split inner tube members 3D coincide with each other to form the central axis O3 of a single inner tube portion 3. At this time, the inner tube portion 3 is located on the inner circumferential side of the outer tube portion 25. In this state, the inner cylindrical portion 3 is arranged coaxially with the outer cylindrical portion 25 ; in other words, the central axis O3 of the inner cylindrical portion 3 coincides with the central axis O25 of the outer cylindrical portion 25 .

[0028] In this specification, the central axis O3 of the inner cylindrical portion 3 or the divided inner cylindrical member 3D is regarded as the central axis O3 of the bushing 1 and the vibration-proof structure S, respectively. Furthermore, in this specification, unless otherwise specified, the direction parallel to the central axis O3 of the bushing 1 and the vibration-proof structure S is referred to as the "axial direction (AD)", the side farther from the center of the bushing 1 and the vibration-proof structure S in the axial direction (AD) is referred to as the "axial outer side", the side closer to the center of the bushing 1 and the vibration-proof structure S in the axial direction (AD) is referred to as the "axial inner side", the direction perpendicular to the central axis O3 of the bushing 1 and the vibration-proof structure S is referred to as the "axial direction", the side closer to the central axis O3 of the bushing 1 and the vibration-proof structure S is referred to as the "inner peripheral side", the side farther from the central axis O3 of the bushing 1 and the vibration-proof structure S is referred to as the "outer peripheral side", the circumferential direction centered on the central axis O3 of the bushing 1 and the vibration-proof structure S is referred to as the "circumferential direction", and the radial direction centered on the central axis O3 of the bushing 1 and the vibration-proof structure S is referred to as the "radial direction". For convenience, in this specification, a direction perpendicular to the axial direction (AD) is referred to as the "longitudinal direction (VD)," one side in the longitudinal direction (VD) is referred to as the "longitudinal first side (VD1)," and the other side in the longitudinal direction (VD) is referred to as the "longitudinal second side (VD2)." Furthermore, a direction perpendicular to the axial direction (AD) and the longitudinal direction (VD) is referred to as the "width direction (WD)." The side closer to the center of the bushing 1 and the vibration-proof structure S in the width direction (WD) is referred to as the "width-direction inner side," and the side farther from the center of the bushing 1 and the vibration-proof structure S in the width direction (WD) is referred to as the "width-direction outer side." In the drawings, these directions are indicated by arrows. For example, the bushing 1 and the vibration-proof structure S can be oriented, during use, so that the axial direction AD is substantially horizontal, the longitudinal direction VD is substantially vertical, and the longitudinal first side VD1 is located on the upper side in the substantially vertical direction. However, the bushing 1 and the vibration-proof structure S may be oriented so that the axial direction AD faces any direction when in use.

[0029] In the examples shown in the figures, the outer tubular portion 25 is configured to have a substantially cylindrical shape when the pair of split assemblies 5 are closely assembled ( FIGS. 6 and 15 ), but may be configured to have any cylindrical shape when the pair of split assemblies 5 are closely assembled. In the first embodiment ( FIG. 6 ), the inner tubular portion is configured to have a substantially cylindrical shape when the pair of split assemblies 5 are closely assembled, and in the second embodiment ( FIG. 15 ), the inner tubular portion is configured to have a cylindrical shape with an inner circumferential surface having a circular cross-sectional shape and an outer circumferential surface having a non-circular cross-sectional shape, but may be configured to have any cylindrical shape when the pair of split assemblies 5 are closely assembled.

[0030] In the examples of the respective figures, each divided outer tube portion 25D, each divided inner tube member 3D, and each divided main body rubber member 4D constitutes approximately half the circumference of the outer tube portion 25, the inner tube portion 3, and the main body rubber portion 4, respectively, and thus each has an approximately semi-cylindrical shape. However, the first divided outer tube portion 25D1, the first divided inner tube member 3D1, and the first divided main body rubber member 4D1 may constitute a portion corresponding to any angular range of the outer tube portion 25, the inner tube portion 3, and the main body rubber portion 4, respectively, and in that case, the second divided outer tube portion 25D2, the second divided inner tube member 3D2, and the second divided main body rubber member 4D2 constitute a portion corresponding to the remaining angular range of the outer tube portion 25, the inner tube portion 3, and the main body rubber portion 4, respectively. It is preferable that the angular ranges (approximately 180° in the examples of each figure) over which each of the first divided outer tube portion 25D1, first divided inner tube member 3D1, and first divided main body rubber member 4D1 extends are approximately the same, and that the angular ranges (approximately 180° in the examples of each figure) over which each of the second divided outer tube portion 25D2, second divided inner tube member 3D2, and second divided main body rubber member 4D2 extend are approximately the same.

[0031] In the examples shown in the figures, the first divided outer cylinder portion 25D1, the first divided inner cylinder member 3D1, and the first divided main body rubber member 4D1 are located on the first longitudinal side VD1 relative to the second divided outer cylinder portion 25D2, the second divided inner cylinder member 3D2, and the second divided main body rubber member 4D2 ( FIGS. 1 and 10 ). When viewed in a cross section perpendicular to the axis ( FIGS. 1 and 10 ), the first divided outer cylinder portion 25D1, the first divided inner cylinder member 3D1, and the first divided main body rubber member 4D1 each have a shape that is convexly curved toward the first longitudinal side VD1, while the second divided outer cylinder portion 25D2, the second divided inner cylinder member 3D2, and the second divided main body rubber member 4D2 each have a shape that is convexly curved toward the second longitudinal side VD2.

[0032] The main body rubber portion 4 is made of rubber. In each divided assembly 5, a part or all of the outer peripheral surface of the divided main body rubber member 4D is joined to the inner peripheral surface of the divided outer tube member 25D. In each divided assembly 5, a part or all of the inner peripheral surface of the divided main body rubber member 4D is joined to the outer peripheral surface of the divided inner tube member 3D. The joining between the main body rubber portion 4 and the outer tube member 25 (and thus between the divided main body rubber member 4D and the divided outer tube member 25D) and the joining between the main body rubber portion 4 and the inner tube member 3 (and thus between the divided main body rubber member 4D and the divided inner tube member 3D) may be performed by any method, such as vulcanization bonding and / or bonding via an adhesive.

[0033] The inner cylindrical portion 3 is configured to be joined (fixed) to the rod-shaped member R with the rod-shaped member R extending on the inner periphery of the inner cylindrical portion 3 (i.e., inside the central hole of the inner cylindrical portion 3) (FIGS. 3 to 6, 12 to 15). In the examples shown in the figures, the inner cylindrical portion 3 is made of a thermoplastic resin (FIGS. 3 to 6, 12 to 15). This allows the inner cylindrical portion 3 to be joined to the rod-shaped member R by welding (thermal welding). An example of the thermoplastic resin that forms the inner cylindrical portion 3 is nylon.

[0034] The bracket portion 2 is made of, for example, metal and / or resin. The pair of split bracket members 2D may be made of the same material or different materials. In the example shown in each figure, the bracket portion 2 further has fitting portions 2D1a, 2D2a and an attachment portion 2D1b in addition to the outer tube portion 25 (FIGS. 1 and 10).

[0035] In the example shown in each figure, the mating portions 2D1a, 2D2a of the bracket portion 2 are configured to allow the pair of split bracket members 2D of the bracket portion 2 (and thus the pair of split assemblies 5) to be assembled by mating ( FIGS. 1 , 6 , 10 , and 15 ). The mating portions 2D1a, 2D2a are configured from a pair of legs 2D1a of the first split bracket member 2D1 and a pair of legs 2D2a of the second split bracket member 2D2. The pair of legs 2D1a of the first split bracket member 2D1 extend from both circumferential ends of the first split outer cylinder portion 25D1 of the first split bracket member 2D1 toward the second vertical side VD2. The pair of legs 2D2a of the second split bracket member 2D2 extend from both circumferential ends of the second split outer cylinder portion 25D2 of the second split bracket member 2D2 toward the second vertical side VD2. The pair of legs 2D2a of the second divided bracket member 2D2 are located more inward in the width direction WD than the pair of legs 2D1a of the first divided bracket member 2D1.

[0036] The first divided assembly 51 defines an accommodation recess 2D1c configured to accommodate the second divided assembly 52. ​​The accommodation recess 2D1c is open on a second vertical side VD2. In the example shown in each figure, the accommodation recess 2D1c is defined by the inner surfaces of the pair of legs 2D1a of the first divided bracket member 2D1 in the width direction WD and the surfaces of the first divided outer tube portion 25D1, the first divided inner tube member 3D1, and the first divided main body rubber member 4D1 on the second vertical side VD2. When the second divided assembly 52 is accommodated in the accommodation recess 2D1c of the first divided assembly 51, it moves relative to the first vertical side VD1 within the accommodation recess 2D1c, and when the pair of legs 2D2a of the second divided bracket member 2D2 reach the back of the accommodation recess 2D1c, they engage with the pair of legs 2D1a of the first divided bracket member 2D1 ( FIGS. 3 , 6 , 12 , and 15 ). When the pair of legs 2D2a of the second divided bracket member 2D2 engage with the pair of legs 2D1a of the first divided bracket member 2D1, and the second divided assembly 52 is completely accommodated in the accommodation recess 2D1c of the first divided assembly 51 ( FIGS. 6 and 15 ), the pair of divided assemblies 5 are closely assembled to each other (closely assembled state of the pair of divided assemblies 5). At this time, the end faces of the split assemblies 5 on the second longitudinal side VD2 are flush with each other.

[0037] The mounting portions 2D1b of the bracket portion 2 are configured to be attached to a vibration receiving member VB (e.g., a part of the vehicle body) (FIGS. 6 and 15). The vibration receiving member VB is, for example, substantially planar. More specifically, in the example of each figure, the first separate bracket member 2D1 of the bracket portion 2 has a pair of mounting portions 2D1b on both sides in the width direction WD. The pair of mounting portions 2D1b extend outward in the width direction WD from ends of the pair of legs 2D1a of the first separate bracket member 2D1 on the second longitudinal side VD2. Each mounting portion 2D1b has a fastening hole 2D1h and is configured to be fastened to the vibration receiving member VB by fastening or the like through the fastening hole 2D1h using a fastener F such as a bolt.

[0038] 6 and 15 , the bushing 1 is configured so that the rod-shaped member R extends on the inner peripheral side of the inner cylindrical portion 3, the pair of divided assemblies 5 are closely assembled to each other (closely assembled state of the pair of divided assemblies 5), and the end faces of the second longitudinal sides VD2 of each divided assembly 5 (more specifically, in the examples of the figures, the end faces of the second longitudinal sides VD2 of each mounting portion 2D1b, each leg portion 2D1a, each leg portion 2D2a, and each second divided outer cylindrical portion 25D2) are placed on the vibration receiving member VB, and the bushing 1 is attached to the vibration receiving member VB by fastening or the like via the mounting portion 2D1b of the bracket portion 2. When the bushing 1 is connected between the rod-shaped member R and the vibration receiving member VB in this manner, the bushing 1 is configured so that the main rubber portion 4 acts to absorb rotational displacement of the rod-shaped member R in the torsional direction and suppress transmission of vibration between the rod-shaped member R and the vibration receiving member VB.

[0039] The vibration-proof structure S (FIGS. 6 and 15) includes a bushing 1 and a rod-shaped member R extending along the inner periphery of an inner cylindrical portion 3 of the bushing 1. The rod-shaped member R is, for example, a torsion bar of a vehicle, particularly a stabilizer bar. In the vibration-proof structure S, the inner cylindrical portion 3 is joined to the rod-shaped member R. More specifically, in the vibration-proof structure S, the inner cylindrical portion 3 is welded to the rod-shaped member R. The vibration-proof structure S may further include a vibration receiving member VB (for example, a part of the vehicle body).

[0040] Next, a description will be given of a method for manufacturing an anti-vibration structure according to the first and second embodiments. The anti-vibration structure manufacturing method includes a bush manufacturing step, a rod-shaped member arranging step, a rod-shaped member joining step, and a bracket portion mounting step.

[0041] First, in the bushing manufacturing process, the bushing 1 is manufactured ( FIGS. 1 to 2 , 10 to 11 ). More specifically, in the first and second embodiments, the bushing 1 obtained in the bushing manufacturing process is a pair of split assemblies 5 separated from each other. In the bushing manufacturing process, each split assembly 5 is manufactured through a vulcanization process. More specifically, for each split assembly 5, for example, in an injection process, a pre-fabricated split bracket member 2D and split inner cylinder member 3D are set in a mold, and unvulcanized rubber for forming the split main body rubber member 4D is injected into the mold cavity. Then, in the vulcanization process, the unvulcanized rubber is vulcanized and molded to connect the split bracket member 2D and split inner cylinder member 3D to each other via the split main body rubber member 4D, thereby obtaining the split assembly 5.

[0042] After the bushing manufacturing process, in a rod-shaped member arrangement process, the rod-shaped member R is arranged so that it extends to the inner periphery of the inner cylindrical portion 3 of the bushing 1 (i.e., within the central hole of the inner cylindrical portion 3) ( FIGS. 3 and 12 ). More specifically, in the first and second embodiments, as illustrated in FIGS. 3 and 12 , respectively, the pair of split assemblies 5 are assembled together by sandwiching the rod-shaped member R between the pair of split inner cylindrical members 3D. At this time, the second split assembly 52 is inserted into the accommodating recess 2D1c of the first split assembly 51 until the pair of split inner cylindrical members 3D come into contact with each other. However, it is not necessarily necessary to insert the second split assembly 52 into the accommodating recess 2D1c of the first split assembly 51 until the second split assembly 52 is completely accommodated in the accommodating recess 2D1c of the first split assembly 51. Immediately after the rod-shaped member placement step, the rod-shaped member R extends to the inner periphery of the inner cylindrical portion 3 of the bushing 1. At this time, it is preferable that the inner periphery of the inner cylindrical portion 3 of the bushing 1 contacts the outer periphery of the rod-shaped member R.

[0043] After the rod-shaped member arranging step, in the rod-shaped member joining step, the inner cylindrical portion 3 of the bushing 1 is joined to the rod-shaped member R with the rod-shaped member R extending on the inner peripheral side of the inner cylindrical portion 3 ( FIGS. 4 , 5 , 13 , and 14 ). As a result, the inner cylindrical portion 3 is joined to the rod-shaped member R extending on the inner peripheral side of the inner cylindrical portion 3. More specifically, in the first and second embodiments, in the rod-shaped member joining step, the inner cylindrical portion 3 is joined to the rod-shaped member R by welding. As a result, the inner cylindrical portion 3 is welded to the rod-shaped member R extending on the inner peripheral side of the inner cylindrical portion 3. A specific welding method, for example, is to heat the rod-shaped member R, thereby melting the inner peripheral surface of the inner cylindrical portion 3 and welding it to the rod-shaped member R. During this time, it is preferable to apply a load to the second split bracket member 2D2 toward the first vertical side VD1, thereby bringing the inner cylindrical portion 3 into close contact with the rod-shaped member R. As an example of a method for heating the rod-shaped member R, a coil K is arranged on the outer periphery of the rod-shaped member R, and an electric current is passed through the coil K to heat the rod-shaped member R by electromagnetic induction heating, as illustrated in FIGS. 4 , 5 , 13 , and 14 . When arranging the coil K on the outer periphery of the rod-shaped member R, the coil K may be arranged on the outer periphery of a portion of the rod-shaped member R that is located further outward in the axial direction AD than the inner cylindrical portion 3 of the bushing 1, as illustrated in FIGS. 4 and 13 . In this way, heat generated in the rod-shaped member R on the inner periphery side of the coil K can travel along the rod-shaped member R to reach the inner cylindrical portion 3 and melt the inner circumferential surface of the inner cylindrical portion 3. This arrangement of the coil K is preferable when the length of the inner cylindrical portion 3 in the axial direction AD is relatively short. Alternatively, when arranging the coil K on the outer periphery of the rod-shaped member R, the coil K may be arranged on the outer periphery of each end of the inner tubular portion 3 of the bushing in the axial direction AD, as shown in FIGS. 5 and 14 . This allows the heat generated in the rod-shaped member R on the inner periphery of the coil K to melt the inner periphery of the inner circumferential surface of the inner tubular portion 3. This arrangement of the coil K is preferable when the length of the inner tubular portion 3 in the axial direction AD is relatively long. In this case, as shown in the examples of FIGS. 5 and 14 , it is preferable that the inner tubular portion 3 extends axially outward from the main rubber portion 4, and the coil K is arranged only on the outer periphery of the portion of the inner tubular portion 3 that is axially outward from the main rubber portion 4.

[0044] After the rod-shaped member joining step, in a bracket portion attaching step, the bracket portion 2 is attached to a vibration receiving member VB (e.g., a part of a vehicle body) VB via the attachment portion 2D1b of the bracket portion 2 by fastening or the like ( FIGS. 6 and 15 ). More specifically, in the first and second embodiments, in the bracket portion attaching step, the second divided bracket member 2D2 (and thus the second divided assembly 52) is pushed deep into the accommodating recess 2D1c toward the first longitudinal side VD1 until the pair of divided assemblies 5 are closely assembled, and further, the attachment portion 2D1b of the bracket portion 2 is attached to the vibration receiving member VB by fastening or the like with the end faces on the second longitudinal side VD2 of each divided assembly 5 (more specifically, in the examples of the figures, the end faces on the second longitudinal side VD2 of each of the attachment portions 2D1b, the leg portions 2D1a, the leg portions 2D2a, and the second divided outer cylinder portion 25D2) placed on the vibration receiving member VB.

[0045] In this manner, the vibration-isolating structure S can be obtained.

[0046] As described above, in the first and second embodiments, the inner cylindrical portion 3 of the bushing 1 is made of a thermoplastic resin. This allows the inner cylindrical portion 3 of the bushing 1 to be joined to the rod-shaped member R by welding. Also, as described above, in the vibration-proof structure manufacturing method and the vibration-proof structure S in the first and second embodiments, the inner cylindrical portion 3 is joined to the rod-shaped member R by welding. This allows the inner cylindrical portion 3 and the rod-shaped member R to be joined (and thus fixed) without the need for an adhesive between them, thereby eliminating the need for a bonding process. By joining the inner circumferential surface of the bushing 1 to the rod-shaped member R by welding in this way, compared to, for example, joining the inner circumferential surface of the bushing 1 to the rod-shaped member R by adhesive, it is possible to simplify the work, reduce the time, and simplify the equipment required for joining the bushing 1 to the rod-shaped member R. This ultimately improves the ease of work when joining the bushing 1 to the rod-shaped member R (and thus the manufacturability of the vibration-proof structure S). Note that bonding by adhesive requires more steps, is more expensive, and requires a long time for the adhesive to dry. Furthermore, by bonding the inner cylindrical portion 3 to the rod-shaped member R, the gap between the inner cylindrical portion 3 and the rod-shaped member R is sealed, preventing muddy water, dust, and the like from entering between the inner cylindrical portion 3 and the rod-shaped member R. If muddy water, dust, and the like were to enter between the inner cylindrical portion 3 and the rod-shaped member R, noise due to stick-slip could be generated, or wear could occur there, creating a gap and resulting in rattle and noise. Furthermore, bonding the inner cylindrical portion 3 to the rod-shaped member R can prevent the bushing 1 from slipping relative to the rod-shaped member R. For example, if the bushing 1 is connected between a torsion bar serving as the rod-shaped member R and a vehicle body serving as the vibration receiving member VB, if the bushing 1 were designed to be slidable relative to the rod-shaped member R, the torsion bar R could slide laterally relative to the vehicle body VB when a lateral force is applied, potentially interfering with other components.

[0047] As described above, in the first and second embodiments, the bushing 1 is divided into a pair of split assemblies 5, each of which includes a split bracket member 2D having a split outer tubular portion 25D, a split inner tubular member 3D, and a split main body rubber member 4D. With this configuration, in the rod-shaped member placement step, the pair of split assemblies 5 are simply assembled together so that the rod-shaped member R is sandwiched between the pair of split inner tubular members 3D, allowing the rod-shaped member R to be easily positioned on the inner circumferential side of the inner tubular portion 3 of the bushing 1. This improves the ease of joining the bushing 1 to the rod-shaped member R (and thus the manufacturability of the vibration-proof structure S). However, the bushing 1 does not have to be divided into a pair of split assemblies 5, and the entire bushing 1 may be integrally constructed.

[0048] As described above, in the rod-shaped member joining step, when the rod-shaped member R is heated by electromagnetic induction heating with the coil K disposed on the outer periphery of the rod-shaped member R, thereby melting the inner circumferential surface of the inner cylindrical portion 3 and welding it to the rod-shaped member R ( FIGS. 4 to 5 , 13 to 14 ), it is particularly easy to simplify the work, reduce the time, and simplify the equipment, thereby further improving the ease of joining the bushing 1 to the rod-shaped member R (and thus the manufacturability of the vibration-proof structure S). However, in the rod-shaped member joining step, the inner cylindrical portion 3 may be joined to the rod-shaped member R by welding using a different method.

[0049] In each example described herein, the vibration-proof structure manufacturing method may further include a rod-shaped member processing step at any timing before the rod-shaped member placement step. In the rod-shaped member processing step, a surface processing treatment using a laser or the like is performed on at least a portion of the outer circumferential surface of the rod-shaped member R, which will come into contact with the inner cylinder portion 3, to form a rough surface portion RG (shown by dot hatching in Figures 4 to 5 and 13 to 14) having multiple minute recesses. As a result, the outer circumferential surface of the rod-shaped member R has a rough surface portion RG having multiple recesses. The rough surface portion RG has a higher surface roughness than other portions of the outer circumferential surface of the rod-shaped member R. Due to the presence of the rough surface portion RG, in the subsequent rod-shaped member joining step, the molten resin of the inner cylinder portion 3 can penetrate into the multiple recesses in the rough surface portion RG and then harden by cooling, thereby providing an anchor effect that more reliably joins the inner cylinder portion 3 and the rod-shaped member R. That is, in this case, the inner cylindrical portion 3 is easily welded to the outer circumferential surface of the rod-shaped member R, particularly to the rough surface portion RG. As the surface processing treatment, for example, the method described in Japanese Patent No. 6489908 may be adopted. However, the rod-shaped member processing step (and thus the rough surface portion RG) is not essential.

[0050] In each example described herein, when the pair of split assemblies 5 are closely assembled ( FIGS. 6 and 15 ), the main rubber portion 4 may be in a compressed state. In this case, an initial strain is applied to the main rubber portion 4, thereby improving durability. In the examples shown in the figures, when the pair of split assemblies 5 are separated from each other ( FIGS. 1 and 10 ), the central axis O3 of the split inner tubular member 3D and the central axis O25 of the split outer tubular portion 25D of each split assembly 5 are positioned at different positions in the longitudinal direction VD. This allows the main rubber portion 4 to be compressed when the pair of split assemblies 5 are closely assembled ( FIGS. 6 and 15 ) and the central axis O3 of the split inner tubular member 3D and the central axis O25 of the split outer tubular portion 25D are aligned. However, this configuration is not essential.

[0051] In each example described in this specification, as in the first embodiment shown in Figures 1 to 9, in each split assembly 5, the outer surface of the split inner tube member 3D may be joined to the split main body rubber member 4D over almost the entire circumferential length of the split inner tube member 3D along the entire length of the axial direction AD of the split inner tube member 3D when viewed in a cross section perpendicular to the axis (Figure 1).

[0052] Alternatively, in each example described herein, as in the second embodiment shown in FIGS. 10 to 17 , in each split assembly 5, the outer circumferential surface of the split inner cylindrical member 3D may have a pair of first joint portions 311 (hereinafter also simply referred to as “joined portions (311)”) and a first non-joined portion 312 (hereinafter also simply referred to as “non-joined portion (312)”) in at least a portion of the axial direction AD of the split inner cylindrical member 3D (i.e., at each axial position in at least a portion of the axial direction AD of the split inner cylindrical member 3D) when viewed in cross section perpendicular to the axis ( FIGS. 10 , 12 , and 15 ). The pair of first joint portions 311 are located at both circumferential ends of the split inner cylindrical member 3D and are each joined to the split main body rubber member 4D. Preferably, the pair of first joint portions 311 extend over the entire length of the split inner cylindrical member 3D in the axial direction AD. The first non-bonded portions 312 extend between the pair of first bonded portions 311 in the circumferential direction and are not bonded to the divided main body rubber member 4D. The first non-bonded portions 312 may be in contact with the divided main body rubber member 4D, as shown in the examples shown in FIGS. 10 and 12 . In this case, the gap G between the first non-bonded portions 312 and the divided main body rubber member 4D is substantially or completely collapsed. In this specification, the term "in contact" with respect to the relationship between the inner tube portion 3 and the main body rubber portion 4 does not necessarily refer to direct contact between the inner tube portion 3 and the main body rubber portion 4 with nothing interposed therebetween, but also includes a case where a lubricant 6 is interposed between the inner tube portion 3 and the main body rubber portion 4 ( FIG. 17 ), as described below, but does not include a case where a member or space other than the lubricant 6 is interposed between the inner tube portion 3 and the main body rubber portion 4. Alternatively, the first non-jointed portion 312 may not be in contact with the divided main body rubber member 4D, and a gap G that actually forms a space may exist between the divided main body rubber member 4D and the first non-jointed portion 312.In each split assembly 5, it is preferable that the outer circumferential surface of the split inner cylindrical member 3D has the above-mentioned pair of first joint portions 311 and first non-joined portions 312 only in the central portion of the split inner cylindrical member 3D in the axial direction AD when viewed in cross section perpendicular to the axis. For example, it is preferable that the outer circumferential surface of the split inner cylindrical member 3D has the above-mentioned pair of first joint portions 311 and first non-joined portions 312 only in a portion along a second non-joined portion 322 ( FIG. 16 ) described below of the split inner cylindrical member 3D in the axial direction AD when viewed in cross section perpendicular to the axis. In each split assembly 5, it is preferable that the outer circumferential surface of the split inner cylindrical member 3D has only joint portions 321 ( FIG. 16 ) over the entire circumferential length at both ends of the split inner cylindrical member 3D in the axial direction AD when viewed in cross section perpendicular to the axis.

[0053] As described above, in each split assembly 5, when the outer surface of the split inner tube member 3D has, in at least a portion of the axial direction AD of the split inner tube member 3D, a pair of first joint portions 311 on both circumferential sides and a first non-joint portion 312 therebetween when viewed in a cross section perpendicular to the axis (Figures 10, 12, and 15), the following advantages are obtained. First, when the split inner cylinder member 3D (and thus the inner cylinder portion 3) is displaced in a torsional direction (the direction in which the inner cylinder portion 3 rotates circumferentially relative to the outer cylinder portion 25) or a twisting direction (the direction in which the central axis O3 of the inner cylinder portion 3 tilts relative to the central axis O25 of the outer cylinder portion 25) relative to the split outer cylinder portion 25D (and thus the outer cylinder portion 25), the split inner cylinder member 3D is fixed to the split main body rubber member 4D at a pair of first joint portions 311 on both circumferential sides, but can slide on the split main body rubber member 4D at the first non-joint portions 312 between them. Therefore, during displacement in the torsional direction or twisting direction, the portions of the split main body rubber member 4D near the pair of first joint portions 311 contribute to the spring rigidity, but the portions of the split main body rubber member 4D near the first non-joint portions 312 contribute little or nothing to the spring rigidity. Therefore, compared to when the split main body rubber member 4D is bonded to the split inner tube member 3D over the entire surface of the split main body rubber member 4D, the area where the split main body rubber member 4D is bonded to the split inner tube member 3D is smaller, thereby reducing the rigidity in the torsional and twisting directions. Consequently, the split inner tube member 3D (and thus the inner tube portion 3) is more likely to swing in the torsional and twisting directions relative to the split outer tube portion 25D (and thus the outer tube portion 25). This improves the performance of the vehicle vibration-proof structure. Furthermore, because the presence of the first non-bonded portion 312 does not affect the displacement in the axial direction, the split main body rubber member 4D (and thus the main rubber portion 4) can exhibit high spring rigidity equivalent to or greater than that of conventional structures when the split inner tube member 3D (and thus the inner tube portion 3) is displaced in the axial direction relative to the split outer tube portion 25D (and thus the outer tube portion 25). This improves the performance of the vehicle vibration-proof structure. Furthermore, the gap G between the divided main body rubber member 4D and the first non-jointed portion 312 of the divided inner cylinder member 3D is sealed by a pair of first jointed portions 311 on both circumferential sides thereof.This prevents dust and other particles from entering the gap G through the mating surfaces of the pair of split assemblies 5, thereby preventing a decrease in the sliding properties between the split main body rubber member 4D and the split inner cylinder member 3D. Furthermore, if lubricant 6 is filled in the gap G as described below (FIG. 17), the lubricant 6 can be prevented from leaking out through the mating surfaces of the pair of split assemblies 5.

[0054] In each example described in this specification, as in the first embodiment shown in Figures 1 to 9, in each split assembly 5, the outer surface of the split inner tube member 3D may be joined to the split main body rubber member 4D along almost the entire axial length when viewed in axial cross section over the entire circumferential length of the split inner tube member 3D (Figure 2).

[0055] Alternatively, in each example described herein, as in the second embodiment shown in FIGS. 10 to 17 , in each split assembly 5, the outer peripheral surface of the split inner cylindrical member 3D may have a pair of second joint portions 321 (hereinafter also simply referred to as “joined portions (321)”) and a second non-joined portion 322 (hereinafter also simply referred to as “non-joined portion (322)”) in at least a portion of the circumferential direction of the split inner cylindrical member 3D (i.e., at each circumferential position in at least a portion of the circumferential direction of the split inner cylindrical member 3D) when viewed in axial cross section ( FIGS. 11 , 16 , and 17 ). The pair of second joint portions 321 are located at both ends of the split inner cylindrical member 3D in the axial direction AD and are each joined to the split main rubber member 4D. Preferably, the pair of second joint portions 321 extend over the entire circumferential length of the split inner cylindrical member 3D. The second non-bonded portion 322 extends between the pair of second bonded portions 321 in the axial direction and is not bonded to the divided main body rubber member 4D. The second non-bonded portion 322 may be in contact with the divided main body rubber member 4D, as in the examples shown in Figures 11, 16, and 17. In this case, the gap G between the second non-bonded portion 322 and the divided main body rubber member 4D is almost or completely collapsed. Alternatively, the second non-bonded portion 322 may not be in contact with the divided main body rubber member 4D, and a gap G that actually forms a space may exist between the divided main body rubber member 4D and the divided main body rubber member 4D. In each split assembly 5, it is preferable that the outer circumferential surface of the split inner cylindrical member 3D has the above-mentioned pair of second joint portions 321 and second non-joined portions 322 only at the circumferential center of the split inner cylindrical member 3D when viewed in axial cross section, and for example, it is preferable that the outer circumferential surface of the split inner cylindrical member 3D has the above-mentioned pair of second joint portions 321 and second non-joined portions 322 only in a portion along the above-mentioned first non-joined portion 312 ( FIG. 15 ) of the split inner cylindrical member 3D when viewed in axial cross section. In each split assembly 5, it is preferable that the outer circumferential surface of the split inner cylindrical member 3D has only joint portions 311 ( FIG. 15 ) over the entire axial length when viewed in axial cross section at both circumferential ends of the split inner cylindrical member 3D.

[0056] As described above, in each split assembly 5, when the outer peripheral surface of the split inner cylinder member 3D has, in at least a portion of the circumferential direction of the split inner cylinder member 3D, a pair of second joint portions 321 on both axial sides and a second non-joint portion 322 therebetween when viewed in axial cross section ( FIGS. 11 , 16 , and 17 ), the following advantages are obtained: First, when the split inner cylinder member 3D (and thus the inner cylinder portion 3) is displaced in a twisting or twisting direction relative to the split outer cylinder portion 25D (and thus the outer cylinder portion 25), the split inner cylinder member 3D is fixed to the split main body rubber member 4D at the pair of second joint portions 321 on both axial sides, but can slide on the split main body rubber member 4D at the second non-joint portion 322 therebetween. Therefore, during displacement in the torsional or twisting direction, the portions of the divided main body rubber member 4D near the pair of second joint portions 321 contribute to spring rigidity, while the portions of the divided main body rubber member 4D near the second non-joint portions 322 contribute little or nothing to spring rigidity. Therefore, compared to a case in which the divided main body rubber member 4D is joined to the divided inner tube member 3D over the entire surface of the divided main body rubber member 4D, the area of ​​the portion where the divided main body rubber member 4D is joined to the divided inner tube member 3D is smaller, thereby reducing rigidity in the torsional and twisting directions. Consequently, the divided inner tube member 3D (and thus the inner tube portion 3) is more likely to swing in the torsional and twisting directions relative to the divided outer tube portion 25D (and thus the outer tube portion 25). This improves the performance of the vehicle vibration-proof structure. Furthermore, because the presence of the second non-bonded portions 322 does not affect displacement in the axial direction, the divided main body rubber member 4D (and thus the main body rubber portion 4) can exhibit high spring rigidity equivalent to or greater than that of conventional structures when the divided inner tube member 3D (and thus the inner tube portion 3) is displaced in the axial direction relative to the divided outer tube portion 25D (and thus the outer tube portion 25). This ultimately improves the performance of the vehicle vibration-proof structure. Furthermore, the gap G between the divided main body rubber member 4D and the second non-bonded portions 322 of the divided inner tube member 3D is sealed by a pair of second bonding portions 321 on both axial sides. This prevents dust and other particles from entering this gap G from both axial sides, thereby preventing a decrease in sliding performance between the divided main body rubber member 4D and the divided inner tube member 3D.Furthermore, if the gap G is filled with lubricant 6 as described below (FIG. 17), the lubricant 6 can be prevented from leaking out from both sides in the axial direction.

[0057] As described above, the bushing 1 of the second embodiment (Figures 10 to 17) has portions (first non-bonded portion 312, second non-bonded portion 322) where the inner tube portion 3 can slide relative to the main rubber portion 4, and therefore can be said to be a so-called "sliding type bushing."

[0058] In the bushing manufacturing process, it is preferable to form the joint portions 311, 321 and the non-joint portions 312, 322 during the vulcanization process. One method for forming the joint portions 311, 321 and the non-joint portions 312, 322 during the vulcanization process is as follows. First, in a surface processing step before the vulcanization step, the portions of the outer surface of the split inner cylinder member 3D that will become the joint portions 311, 321 are subjected to a surface processing treatment using a laser or the like, thereby forming multiple minute recesses in those portions of the split inner cylinder member 3D. The portions of the outer surface of the split inner cylinder member 3D that will become the non-joint portions 312, 322 are not subjected to the surface processing. Then, in an injection step, unvulcanized rubber for forming the split main body rubber member 4D is injected into a mold in which the split bracket member 2D and the split inner cylinder member 3D are set. Then, in a vulcanization step, the split assembly 5 is vulcanized and molded using the mold. In this case, during the vulcanization process, the divided main body rubber member 4D penetrates into multiple small recesses in the surface-treated portions of the outer peripheral surface of the divided inner tube member 3D and is bonded to these portions by an anchor effect, forming bonded portions 311, 321 there. Meanwhile, the divided main body rubber member 4D is not bonded to the portions of the outer peripheral surface of the divided inner tube member 3D that have not been surface-treated, forming non-bonded portions 312, 322 there. Note that, for example, the surface treatment methods described in JP 2020-116862 A and Japanese Patent No. 6489908 may be used. Another method for forming the bonded portions 311, 321 and the non-bonded portions 312, 322 during the vulcanization process is as follows. First, in an adhesive sheet attachment process prior to the vulcanization process, an adhesive sheet is attached to the portions of the outer peripheral surface of the divided inner tube member 3D that will become the bonded portions 311, 321. At this time, the adhesive sheet is not attached to the portions of the outer surface of the split inner cylinder member 3D that will become the non-jointed portions 312, 322. Then, in the injection process, unvulcanized rubber for forming the split main body rubber member 4D is injected into the mold in which the split bracket member 2D and the split inner cylinder member 3D are set, and then, in the vulcanization process, the split assembly 5 is vulcanized and molded using the mold.In this case, during the vulcanization process, the divided main body rubber member 4D is bonded to the portions of the outer circumferential surface of the divided inner tube member 3D where the adhesive sheet is attached, forming bonded portions 311, 321, while not being bonded to the portions of the outer circumferential surface of the divided inner tube member 3D where the adhesive sheet is not attached, forming non-bonded portions 312, 322. Note that, for example, the adhesive sheet described in Japanese Patent No. 4681634 may be used as this adhesive sheet. Another method for forming the bonded portions 311, 321 and non-bonded portions 312, 322 during the vulcanization process is as follows. First, in an adhesive application process before the vulcanization process, the portions of the outer circumferential surface of the divided inner tube member 3D that will become the non-bonded portions 312, 322 are masked, and then adhesive is applied to the portions of the outer circumferential surface of the divided inner tube member 3D that will become the bonded portions 311, 321. This prevents adhesive from being applied to the portions of the outer circumferential surface of the divided inner tube member 3D that will become the non-bonded portions 312, 322. The masking is then removed. Then, in the injection process, unvulcanized rubber for forming the divided main body rubber member 4D is injected into the mold in which the divided bracket member 2D and the divided inner cylinder member 3D are set. Then, in the vulcanization process, the divided assembly 5 is vulcanized and molded using the mold. In this case, during the vulcanization process, the divided main body rubber member 4D is bonded to the portions of the outer surface of the divided inner cylinder member 3D where adhesive is applied, forming bonded portions 311, 321. Furthermore, the divided main body rubber member 4D is not bonded to the masked portions of the outer surface of the divided inner cylinder member 3D (i.e., where adhesive is not applied), forming non-bonded portions 312, 322. However, methods for forming the bonded portions 311, 321 and non-bonded portions 312, 322 other than those described above may also be used.

[0059] As shown in FIG. 17 , a lubricant 6 may be interposed between the divided main body rubber member 4D and the non-bonded portions 312, 322 of the divided inner cylinder member 3D. In this case, the gap G between the divided main body rubber member 4D and the non-bonded portions 312, 322 of the divided inner cylinder member 3D is filled with the lubricant 6. Note that FIG. 17 exaggerates the size of this gap G, but in reality, this gap G may be almost or completely collapsed. Therefore, the thickness of the layer of lubricant 6 may actually be very thin. In this case, the divided main body rubber member 4D and the non-bonded portions 312, 322 of the divided inner cylinder member 3D come into contact with each other via the lubricant 6. The lubricant 6 may be, for example, lubricating oil. By providing the lubricant 6 between the divided main body rubber member 4D and the non-jointed portions 312, 322 of the divided inner cylinder member 3D, the frictional resistance between the divided main body rubber member 4D and the non-jointed portions 312, 322 of the divided inner cylinder member 3D can be reduced, which in turn makes it easier for the non-jointed portions 312, 322 of the divided inner cylinder member 3D to slide relative to the divided main body rubber member 4D. This makes it even easier for the inner cylinder portion 3 to swing in the twisting and prying directions. However, as illustrated in Figures 15 and 16, the lubricant 6 does not necessarily have to be provided between the divided main body rubber member 4D and the non-jointed portions 312, 322 of the divided inner cylinder member 3D.

[0060] When the lubricant 6 is interposed between the non-jointed portions 312, 322 of the split inner tubular member 3D and the split main body rubber member 4D ( FIG. 17 ), it is preferable to perform a lubricant injection process after the vulcanization process in the bushing manufacturing process. When performing the lubricant injection process, injection holes H are formed in each split assembly 5 of the bushing 1 in advance. The injection holes H connect the gap G between the non-jointed portions 312, 322 of the split inner tubular member 3D and the split main body rubber member 4D to the outside of the split assembly 5. As shown in the example of FIG. 17 , the injection holes H may pass through the split outer tubular portion 25D and the split main body rubber member 4D of the split assembly 5 between the gap G and the outside of the split assembly 5. In this case, any method may be used to form the injection holes H in advance. For example, a through-hole may be formed in the corresponding location of the split outer tubular member 25D in advance, and a protrusion for forming the injection holes H may be provided on the mold used during the injection and vulcanization processes. In the lubricant injection step, the lubricant 6 is injected from the outside through the injection hole H into the gap G between the non-jointed portions 312, 322 of the divided inner cylinder member 3D and the divided main body rubber member 4D.

[0061] When the bushing manufacturing process includes the lubricant injection step as described above, a plug insertion step may be performed after the lubricant injection step. When the plug insertion step is performed, as shown in Figure 17, a plug P is inserted into the injection hole H from the outside of the split assembly 5 to close the injection hole H. This prevents the lubricant 6 from leaking to the outside.

[0062] 10 to 17 , in each split assembly 5, the outer circumferential surface of the split inner cylinder member 3D may have a first protrusion 33 (protrusion) that protrudes outward at the axial center of the split inner cylinder member 3D in at least a portion of the circumferential direction of the split inner cylinder member 3D (i.e., at each circumferential position in at least a portion of the circumferential direction of the split inner cylinder member 3D) when viewed in axial cross section ( FIG. 16 ). In this case, the portion of the inner circumferential surface of the split main body rubber member 4D that comes into contact with the first protrusion 33 of the split inner cylinder member 3D has a concave shape recessed outward to fit the first protrusion 33. When the outer peripheral surface of the divided inner cylinder member 3D has the first protrusion 33 (FIG. 16), the thickness of the divided main body rubber member 4D located on the outer peripheral side of the first protrusion 33 is thinner than when the divided inner cylinder member 3D does not have the first protrusion 33 (see, for example, FIGS. 4 to 5), and therefore the divided main body rubber member 4D can exhibit higher spring rigidity against relative displacement in the direction perpendicular to the axis of the divided inner cylinder member 3D. Furthermore, when the outer peripheral surface of the divided inner cylinder member 3D has the first protrusion 33 (FIG. 16), unlike when the divided inner cylinder member 3D does not have the first protrusion 33 (see, for example, FIGS. 4 to 5), the presence of side surfaces on both axial sides of the first protrusion 33 improves durability and makes it easier to suppress axial displacement of the divided inner cylinder member 3D, thereby suppressing axial movement of the rod-shaped member R. In each split assembly 5, the outer peripheral surface of the split inner cylindrical member 3D may, in at least a portion of the circumferential direction of the split inner cylindrical member 3D, extend substantially linearly along the axial direction on both sides of the axial direction AD relative to the first protrusion 33 when viewed in an axial cross section ( FIG. 16 ). In each split assembly 5, the outer peripheral surface of the split inner cylindrical member 3D may have the first protrusion 33 in the axial center of the split inner cylindrical member 3D only in the circumferential center of the split inner cylindrical member 3D when viewed in an axial cross section; for example, the outer peripheral surface may have the first protrusion 33 in the axial center of the split inner cylindrical member 3D only in a portion along the first non-joint portion 312 ( FIG. 15 ) of the split inner cylindrical member 3D in the circumferential direction when viewed in an axial cross section.In each split assembly 5, the outer surface of the split inner tube member 3D may not have a first protrusion 33 at both circumferential ends of the split inner tube member 3D when viewed in axial cross section, and may extend approximately linearly along the axial direction over the entire axial length.

[0063] In each split assembly 5, as shown in the example of Fig. 16, when viewed in axial cross section, the pair of second joint portions 321 preferably constitute at least a portion of the outer circumferential surface of the split inner cylinder member 3D on both sides of the first protruding portion 33 in the axial direction AD, and the second non-joined portion 322 preferably constitutes at least a portion (preferably the entirety) of the first protruding portion 33 of the split inner cylinder member 3D. In this case, when the split inner cylinder member 3D is displaced in the prying direction, the second non-joined portion 322, which includes the first protruding portion 33 of the split inner cylinder member 3D, slides more easily against the split main body rubber member 4D. This further reduces spring rigidity against displacement in the prying direction.

[0064] In each divided assembly 5, the protruding shape of the first protruding portion 33 when viewed in axial cross section may be any shape as long as it protrudes outward. As illustrated in FIG. 16 , in each divided assembly 5, the first protruding portion 33 may have a recessed portion 33a recessed inward at its end surface protruding outward toward the outer periphery when viewed in axial cross section. The radial depth of the recessed portion 33a is smaller than the radial height of the first protruding portion 33. In this case, the portion of the inner circumferential surface of the divided main body rubber member 4D that contacts the recessed portion 33a of the first protruding portion 33 of the divided inner tube member 3D forms a convex shape protruding inward to fit the recessed portion 33a. This configuration further reduces axial displacement of the divided inner tube member 3D, thereby further reducing axial movement of the rod-shaped member R. 16, in each split assembly 5, the inner peripheral surface of the split outer cylinder portion 25D may have a protrusion 25a that protrudes inward toward the recess 33a on the outer peripheral side of the recess 33a of the first protrusion 33 of the split inner cylinder member 3D when viewed in axial cross section. With this configuration, axial displacement of the split inner cylinder member 3D can be further suppressed, and ultimately, axial movement of the rod-shaped member R can be further suppressed.

[0065] 10 to 17 , in each split assembly 5, the outer circumferential surface of the split inner cylinder member 3D may have a second protrusion 34 (protrusion) that protrudes toward the outer circumferential side at the circumferential center of the split inner cylinder member 3D in at least a portion of the axial direction of the split inner cylinder member 3D (i.e., at each axial position in at least a portion of the axial direction AD of the split inner cylinder member 3D) when viewed in a cross section perpendicular to the axis ( FIG. 15 ). In this case, the portion of the inner circumferential surface of the split main body rubber member 4D that comes into contact with the second protrusion 34 of the split inner cylinder member 3D will have a concave shape recessed toward the outer circumferential side to fit the second protrusion 34. When the outer peripheral surface of the divided inner cylinder member 3D has the second protrusion 34 (FIG. 15), the thickness of the divided main body rubber member 4D located on the outer peripheral side of the second protrusion 34 is thinner than when the divided inner cylinder member 3D does not have the second protrusion 34 (see FIG. 6, for example), and therefore the divided main body rubber member 4D can exhibit higher spring rigidity against relative displacement in the axial direction of the divided inner cylinder member 3D. In each divided assembly 5, the outer peripheral surface of the divided inner cylinder member 3D may extend circumferentially on both circumferential sides of the second protrusion 34 in at least a portion of the circumferential direction of the divided inner cylinder member 3D when viewed in a cross section perpendicular to the axial direction (FIG. 16). In each split assembly 5, the outer circumferential surface of the split inner cylindrical member 3D may have the second protrusion 34 in the axial center of the split inner cylindrical member 3D only at the circumferential center of the split inner cylindrical member 3D when viewed in cross section perpendicular to the axis, for example, the second protrusion 34 may be present in the axial center of the split inner cylindrical member 3D only in a portion along the second non-joint portion 322 ( FIG. 16 ) of the split inner cylindrical member 3D in the axial direction when viewed in cross section perpendicular to the axis. In each split assembly 5, the outer circumferential surface of the split inner cylindrical member 3D may not have the second protrusion 34 at both axial end portions of the split inner cylindrical member 3D when viewed in cross section perpendicular to the axis, but may extend along the circumferential direction over the entire circumferential length.

[0066] In each split assembly 5, as shown in the example of Figure 15, when viewed in a cross section perpendicular to the axis, it is preferable that the pair of joint portions 311 constitute at least a portion of the outer circumferential surface of the split inner cylinder member 3D on both sides of the second protrusion 34 in the circumferential direction, and the non-joint portion 312 constitutes at least a portion (preferably the entirety) of the second protrusion 34 of the split inner cylinder member 3D. In this case, when the split inner cylinder member 3D is displaced in the prying direction, the non-joint portion 312, which includes the second protrusion 34 of the split inner cylinder member 3D, slides more easily against the split main body rubber member 4D. This further reduces the spring rigidity against displacement in the prying direction.

[0067] The bushing, vibration-damping structure, and vibration-damping structure manufacturing method of the present invention are suitable for use in the connecting portion between a rod-shaped member in a vehicle (e.g., a torsion bar of the vehicle, particularly a stabilizer bar) and a vibration-receiving member (e.g., a part of the vehicle body).

[0068] S: vibration-proof structure, 1: bush, 2: bracket portion, 2D: split bracket member, 2D1: first split bracket member, 2D1a: leg portion (fitting portion), 2D1b: mounting portion, 2D1h: fastening hole, 2D1c: accommodation recess, 2D2: second split bracket member, 2D2a: leg portion (fitting portion), 25: outer cylinder portion, 25D: split outer cylinder portion, 25D1: first split outer cylinder portion, 25D2: second split outer cylinder portion, 25a: protrusion portion, 3: inner cylinder portion, 3D: split inner cylinder member, 3D1: first split inner cylinder member, 3D2: second split inner cylinder member, 311: first joint portion (joining portion), 312: first non-joining portion (non-joining portion), 321: second joint portion (joining portion), 322: Second non-bonded portion (non-bonded portion), 33: First protruding portion (protruding portion), 33a: Recessed portion, 34: Second protruding portion (protruding portion), 4: Main body rubber portion, 4D: Divided main body rubber member, 4D1: First divided main body rubber member, 4D2: Second divided main body rubber member, 5: Divided assembly, 51: First divided assembly, 52: Second divided assembly, 6: Lubricant, G: Gap, H: Injection hole, P: Plug, F: Fastener, O25: Central axis of outer cylindrical portion (central axis of divided outer cylindrical portion), O3: Central axis of inner cylindrical portion (central axis of divided inner cylindrical member, central axis of bushing, central axis of vibration-proof structure), R: Rod-shaped member, RG: Rough surface portion, AD: Axial direction, VD: Longitudinal direction, VD1: First longitudinal side, VD2: Second longitudinal side, WD: Width direction, K: Coil, VB: Vibration receiving member

Claims

1. A bushing comprising: a bracket portion having an outer tube portion; an inner tube portion; and a main rubber portion connecting the outer tube portion and the inner tube portion together, wherein the inner tube portion is made of a thermoplastic resin.

2. The bush as described in claim 1, wherein the bush comprises a pair of split assemblies, each of the split assemblies comprising: a split bracket member which forms part of the bracket portion and has a split outer tube portion which forms a circumferential portion of the outer tube portion; a split inner tube member which forms a circumferential portion of the inner tube portion; and a split main body rubber member which forms a circumferential portion of the main body rubber portion and connects the split outer tube portion of the split bracket member and the split inner tube member.

3. The bushing according to claim 1, wherein said inner cylindrical portion is welded to a rod-shaped member extending along the inner periphery of said inner cylindrical portion.

4. A vibration-proof structure comprising the bush according to claim 1 and a rod-shaped member extending along the inner periphery of the inner cylindrical portion of the bush, the inner cylindrical portion being welded to the rod-shaped member.

5. The vibration-proof structure according to claim 4, wherein the outer peripheral surface of the rod-shaped member has a rough surface portion having a plurality of recesses, and the inner cylindrical portion is welded to the rough surface portion of the rod-shaped member.

6. A method for manufacturing an anti-vibration structure for manufacturing the anti-vibration structure described in claim 4, comprising: a bush manufacturing step of manufacturing the bush; and a rod-shaped member joining step of joining the inner cylindrical portion to the rod-shaped member by welding, with the rod-shaped member extending on the inner peripheral side of the inner cylindrical portion of the bush.

7. A method for manufacturing an anti-vibration structure as described in claim 6, wherein in the rod-shaped member joining process, a coil is placed on the outer periphery of the rod-shaped member and the rod-shaped member is heated by electromagnetic induction heating, thereby melting the inner surface of the inner tube portion and fusing it to the rod-shaped member.

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