Cylindrical vibration isolation device

Abstract

To obtain stable quality by effectively applying blast processing, blowing processing or the like to an intermediate sleeve to the whole of the intermediate sleeve, in a cylindrical vibration isolator and the intermediate sleeve.SOLUTION: In a cylindrical vibration isolator 10 in which an inner shaft member 12 and an outer cylinder member 14 are connected to each other by a main-body rubber elastic body 16, and a cylindrical intermediate sleeve 18 extending in a circumferential direction between radial directions of the inner shaft member 12 and the outer cylinder member 14 firmly adheres to the main-body rubber elastic body 16, a slit 22 penetrating in an axial direction is formed at a part of the intermediate sleeve 18 in the circumferential direction, both-end portions of the slit 22 are formed as straight parts 24, 24 extending in the axial direction, and a direct overlap margin of the straight parts 24, 24 at both sides in an axial-direction view is set smaller than a thickness dimension of the intermediate sleeve 18 in the radial direction.SELECTED DRAWING: Figure 10A

Description

Technical Field

[0001] The present invention relates to a cylindrical vibration isolator applied to engine mounts, suspension bushes, etc. of automobiles, and an intermediate sleeve for the cylindrical vibration isolator.

Background Art

[0002] Conventionally, cylindrical vibration isolators applied to engine mounts, suspension bushes, etc. of automobiles have been known. The cylindrical vibration isolator has a structure in which an inner shaft member (inner cylinder) and an outer cylinder member (outer cylinder) are connected by a main body rubber elastic body (rubber-like elastic body), like the bush disclosed in Japanese Utility Model Laid-Open No. 2-034839 (Patent Document 1).

[0003] Also, in a cylindrical vibration isolator, for the purpose of achieving both low spring characteristics in the torsional direction and high spring characteristics in the direction perpendicular to the axis, a cylindrical intermediate sleeve may be adopted. The intermediate sleeve is arranged so as to extend in the circumferential direction between the radial directions of the inner shaft member and the outer cylinder member, and is connected to the inner shaft member and the outer cylinder member by the main body rubber elastic body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, the intermediate sleeve may be a continuous cylindrical shape around its entire circumference, but for example, Patent Document 1 shows an intermediate sleeve (intermediate cylinder) in which a part of the circumference is divided by a slit. According to this, when the outer cylindrical member is processed to reduce its diameter, the slit width is narrowed, which allows for diameter reduction deformation of the intermediate sleeve, making it possible to pre-compress not only the rubber between the outer cylindrical member and the intermediate sleeve in the radial direction, but also the rubber between the intermediate sleeve and the inner shaft member in the radial direction.

[0006] However, when a slit is formed in the intermediate sleeve to create a C-shaped tube, as in Patent Document 1, a novel problem has emerged: when a large number of intermediate sleeves are subjected to blast treatment (roughening by spraying blasting material) as a pretreatment for vulcanizing and bonding the main rubber elastic body, other intermediate sleeves may enter the slits in the drum of the blast treatment equipment. When other intermediate sleeves enter the slits, the overlapping portions of the intermediate sleeves may not be sufficiently treated.

[0007] The problem to be solved by the present invention is to provide a cylindrical vibration damping device with a novel structure that can achieve stable quality by effectively applying blast treatment or the like to the entire intermediate sleeve.

[0008] Another objective is to provide an intermediate sleeve for a cylindrical vibration isolation device with a novel structure that makes it difficult for other intermediate sleeves to get stuck in the slit. [Means for solving the problem]

[0009] The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is illustrative and can be combined with others as appropriate. Furthermore, the multiple components described in each embodiment can be recognized and adopted as independently as possible, and can be combined with any component described in another embodiment as appropriate. Thus, the present invention is not limited to the embodiments described below, and various other embodiments can be realized.

[0010] The first embodiment is a cylindrical vibration damping device in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, and a cylindrical intermediate sleeve extending circumferentially between the inner shaft member and the outer cylindrical member is fixed to the main rubber elastic body, wherein a slit that penetrates axially is formed in a part of the circumferential direction of the intermediate sleeve, and both ends of the slit are straight portions that extend axially, and the direct overlap of the straight portions on both sides in an axial view is smaller than the radial thickness dimension of the intermediate sleeve.

[0011] When the outer cylindrical member is reduced in diameter to apply radial pre-compression to the main rubber elastic body, the intermediate sleeve is deformed so that the slit width narrows, thus reducing its diameter. As a result, the portion of the main rubber elastic body on the inner circumference side of the intermediate sleeve is also effectively pre-compressed radially.

[0012] For example, when performing blasting or other treatments on multiple intermediate sleeves simultaneously, the drum of the processing equipment may be moved while the multiple intermediate sleeves are housed in the drum. In this case, according to the cylindrical vibration isolation device constructed in accordance with this embodiment, the direct overlap of the straight sections that make up both axial ends of the slit is smaller than the radial thickness dimension of the intermediate sleeve when viewed in the axial direction. Therefore, it is suppressed that other intermediate sleeves will enter into the slit of an intermediate sleeve across both straight sections, making it easier for other intermediate sleeves to detach from the slit. Consequently, it is possible to prevent partial insufficient blasting or other treatments due to the entry of intermediate sleeves into the slit, and a cylindrical vibration isolation device with the desired quality can be stably obtained. Furthermore, even if other intermediate sleeves are held in place and do not detach from the slit of an intermediate sleeve, the other intermediate sleeves will not enter into the straight sections on both sides of the slit, reducing the area that is not covered by blasting or other treatments due to the entry of other intermediate sleeves into the slit.

[0013] The second embodiment is a cylindrical vibration damping device as described in the first embodiment, wherein the straight portions on both sides of the slit are formed at mutually different positions in the circumferential direction of the intermediate sleeve, and the slit has an intermediate portion that connects the straight portions on both sides to each other in the circumferential direction.

[0014] In the cylindrical vibration isolation device with a structure according to this embodiment, the straight sections on both sides are formed at mutually different positions in the circumferential direction of the intermediate sleeve, and the slit is formed by the connection of these straight sections by the intermediate section. Therefore, it is possible to effectively allow the intermediate sleeve to be reduced in diameter due to the formation of the slit, while effectively preventing other intermediate sleeves from entering the slit across the straight sections on both sides.

[0015] A third embodiment is a cylindrical vibration damping device described in the first or second embodiment, wherein an intermediate rubber is provided in the intermediate portion of the slit, connecting the axial portions on both sides of the intermediate sleeve with respect to the intermediate portion.

[0016] In the cylindrical vibration damping device constructed according to this embodiment, the intermediate portion extending circumferentially in the middle of the axial direction of the intermediate sleeve is formed of intermediate rubber during the molding of the main rubber elastic body. However, when the diameter of the intermediate sleeve is reduced, this intermediate rubber undergoes shear deformation, resulting in a lower spring constant compared to compression deformation, which does not hinder the diameter reduction deformation of the intermediate sleeve. Therefore, while effectively achieving pre-compression of the main rubber elastic body by the diameter reduction deformation of the intermediate sleeve, the formation of the circumferentially extending intermediate portion significantly shifts the circumferential position of the straight portions on both sides, preventing other intermediate sleeves from entering the slits across the straight portions on both sides.

[0017] The fourth embodiment is an intermediate sleeve for a cylindrical vibration damping device, comprising a cylindrical portion extending circumferentially between an inner shaft member and an outer cylindrical member in the radial direction, wherein the cylindrical portion is connected to the inner shaft member and the outer cylindrical member by a main rubber elastic body, and a slit penetrating axially is formed in a part of the circumferential direction of the cylindrical portion, and both ends of the slit are straight portions extending axially, and the direct overlap of the straight portions on both sides in an axial view is smaller than the radial thickness dimension of the cylindrical portion.

[0018] According to the intermediate sleeve for a cylindrical vibration damping device constructed in accordance with this embodiment, the cylindrical portion of another intermediate sleeve can be prevented from entering the slit across the straight portions on both axial sides, and other intermediate sleeves that have entered the slit of an intermediate sleeve can be easily removed from the slit.

[0019] In addition, in a fourth embodiment, the straight portions on both sides of the slit are formed at mutually different positions in the circumferential direction of the cylindrical portion, and the slit also has an intermediate portion that connects the straight portions on both sides in the circumferential direction. This configuration can be used to obtain the same effects as in the second embodiment. [Effects of the Invention]

[0020] According to the present invention, in a cylindrical vibration damping device, by suppressing the entry of other intermediate sleeves into the slits, blast treatment and the like can be effectively applied to the entire intermediate sleeve, thereby achieving stable quality.

[0021] Furthermore, in the case of an intermediate sleeve for a cylindrical vibration isolation device, it is possible to prevent the cylindrical portion of another intermediate sleeve from entering the slit of the cylindrical portion. [Brief explanation of the drawing]

[0022] [Figure 1] Front view of a cylindrical vibration damper as the first embodiment of the present invention. [Figure 2] Section II-II in Figure 1 [Figure 3] Cross-sectional view taken along line III-III of FIG. 1 [Figure 4] Cross-sectional view taken along line IV-IV of FIG. 2 [Figure 5] Cross-sectional view taken along line V-V of FIG. 2 [Figure 6] Front view showing the cylindrical vibration isolator shown in FIG. 1 in a state before diameter reduction processing [Figure 7] Cross-sectional view taken along line VII-VII of FIG. 6 [Figure 8] Cross-sectional view taken along line VIII-VIII of FIG. 7 [Figure 9] Cross-sectional view taken along line IX-IX of FIG. 7 [Figure 10A] Plan view of the intermediate sleeve constituting the cylindrical vibration isolator shown in FIG. 6 [Figure 10B] Plan view of the intermediate sleeve constituting the cylindrical vibration isolator shown in FIG. 1 [Figure 11] Front view showing the cylindrical vibration isolator as the second embodiment of the present invention in a state before diameter reduction processing [Figure 12] Cross-sectional view taken along line XII-XII of FIG. 11 [Figure 13] Cross-sectional view taken along line XIII-XIII of FIG. 12 [Figure 14A] Plan view of the intermediate sleeve constituting the cylindrical vibration isolator shown in FIG. 11 [Figure 14B] Plan view showing the intermediate sleeve shown in FIG. 14A in a state after diameter reduction processing [Figure 15] Front view showing the cylindrical vibration isolator as the third embodiment of the present invention in a state before diameter reduction processing [Figure 16] Cross-sectional view taken along line XVI-XVI of FIG. 15 [Figure 17] Cross-sectional view taken along line XVII-XVII of FIG. 16 [Figure 18A] Plan view of the intermediate sleeve constituting the cylindrical vibration isolator shown in FIG. 15 [Figure 18B] Plan view showing the intermediate sleeve shown in FIG. 18A in a state after diameter reduction processing [Figure 19A] Plan view showing the intermediate sleeve constituting the cylindrical vibration isolator as the fourth embodiment of the present invention in a state before diameter reduction processing [Figure 19B]Figure 19A is a plan view showing the intermediate sleeve after diameter reduction processing. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to the drawings.

[0024] Figures 1 to 5 show a cylindrical vibration damping device 10 as a first embodiment of the present invention. The cylindrical vibration damping device 10 has a structure in which an inner shaft member 12 and an outer cylindrical member 14 are connected by a main rubber elastic body 16. In the following description, as a general rule, the vertical direction refers to the vertical direction in Figure 1, the left-right direction refers to the left-right direction in Figure 1, and the front-back direction refers to the left-right direction in Figure 2. Figures 6 to 9 show the state of the cylindrical vibration damping device 10 before the outer cylindrical member 14 is reduced in diameter (an integrally vulcanized molded product of the main rubber elastic body 16). Below, we will describe each component and part of the cylindrical vibration damping device 10 before the reduction in diameter, and then describe the deformation of the outer cylindrical member 14 due to the reduction in diameter.

[0025] The inner shaft member 12 is a rigid member made of metal or synthetic resin, and has a thick-walled, small-diameter, substantially cylindrical shape. The inner shaft member 12 has a symmetrical shape, regardless of its axial orientation.

[0026] The outer cylindrical member 14 is a rigid member made of metal or synthetic resin, and has a roughly cylindrical shape with a thinner wall and larger diameter compared to the inner shaft member 12. The outer cylindrical member 14 has a shorter axial length compared to the inner shaft member 12. The outer cylindrical member 14 has a symmetrical shape that is independent of its axial orientation. The outer circumferential surfaces of both axial ends of the outer cylindrical member 14 have a tapered shape that becomes smaller in diameter towards the axial outward direction.

[0027] As shown in Figures 6 to 9, the inner shaft member 12 is inserted through the outer cylindrical member 14, and a cylindrical intermediate sleeve 18 is positioned radially between the inner shaft member 12 and the outer cylindrical member 14. The intermediate sleeve 18 is a rigid member made of metal or synthetic resin and has a cylindrical portion 20 that is substantially cylindrical overall. In this embodiment, the cylindrical portion 20 of the intermediate sleeve 18 is even thinner than the outer cylindrical member 14. The cylindrical portion 20 has a smaller axial dimension than the outer cylindrical member 14. The cylindrical portion 20 has a larger diameter than the inner shaft member 12 and a smaller diameter than the outer cylindrical member 14, and extends circumferentially between the inner shaft member 12 and the outer cylindrical member 14 in the radial direction. The cylindrical portion 20 is spaced outward from the outer circumferential surface of the inner shaft member 12 and inward from the inner circumferential surface of the outer cylindrical member 14.

[0028] As shown in Figure 10A, a slit 22 is formed in the cylindrical portion 20 of the intermediate sleeve 18, which penetrates the entire structure axially. The slit 22 is provided in a part of the circumferential direction of the intermediate sleeve 18, and the intermediate sleeve 18 is divided in a part of the circumferential direction by the slit 22, resulting in a roughly C-shaped cylindrical form.

[0029] The slit 22 has straight sections 24, 24 at both ends that extend in the axial direction. The straight sections 24 in this embodiment extend in a straight line. The straight sections 24 extend in the axial direction with a substantially constant width dimension, but a draft taper may be provided, for example, to facilitate the removal of the mold inserted when molding the main rubber elastic body 16, which will be described later. In addition, guide surfaces 26 with an expanding shape are formed at the axial end of the straight section 24, inclined to both sides in the circumferential direction toward the axial outward direction.

[0030] The straight portions 24, 24 on both sides in the axial direction are formed at mutually different positions in the circumferential direction of the intermediate sleeve 18, and in this embodiment, they are formed at mutually separated positions in the circumferential direction of the intermediate sleeve 18. In short, the straight portions 24, 24 in this embodiment do not overlap each other in the axial view, and the overlap of these straight portions 24, 24 in the axial view is less than 0. Therefore, the overlap of the straight portions 24, 24 is smaller than the radial thickness dimension of the cylindrical portion 20 of the intermediate sleeve 18.

[0031] The straight sections 24, 24 are interconnected by an intermediate section 28. The intermediate section 28 extends in the circumferential direction of the intermediate sleeve 18, with one end in the circumferential direction connected to the front straight section 24 and the other end in the circumferential direction connected to the rear straight section 24. The width dimension w2 of the slit 22 in the intermediate section 28 may be smaller than the width dimension w1 of the slit 22 in the straight sections 24, 24, but in this embodiment, w2 > w1. The width dimension w1 of the slit 22 in the straight sections 24, 24 is the width dimension of the straight section 24 in the intermediate sleeve 18 before diameter reduction, and is set according to the amount of diameter reduction deformation of the intermediate sleeve 18, which will be described later. In this embodiment, the intermediate sleeve 18 has a 180-degree rotationally symmetric shape with respect to the axis of symmetry L, which extends in the direction perpendicular to the axis (the direction perpendicular to the plane of the paper in Figure 10A) through the center of the slit 22 on both axial sides, and the axial orientation is irrelevant.

[0032] As shown in Figures 6 to 9, a main rubber elastic body 16 is formed radially between the inner shaft member 12, on which the intermediate sleeve 18 is positioned, and the outer cylindrical member 14. The main rubber elastic body 16 is thick-walled and has a substantially cylindrical shape. Its inner circumferential surface is vulcanized and bonded to the outer circumferential surface of the inner shaft member 12, and its outer circumferential surface is vulcanized and bonded to the inner circumferential surface of the outer cylindrical member 14. Furthermore, the intermediate sleeve 18 is vulcanized and bonded in the radial middle of the main rubber elastic body 16, dividing the main rubber elastic body 16 into an inner circumferential side and an outer circumferential side of the intermediate sleeve 18. Thus, the main rubber elastic body 16 is composed of an inner circumferential rubber 30 that connects the inner shaft member 12 and the cylindrical portion 20 of the intermediate sleeve 18, and an outer circumferential rubber 32 that connects the cylindrical portion 20 of the intermediate sleeve 18 and the outer cylindrical member 14. The intermediate sleeve 18 is almost entirely covered by the main rubber elastic body 16, and the axial end of the cylindrical portion 20 is partially exposed from the main rubber elastic body 16 at multiple locations in the circumferential direction.

[0033] The inner circumferential groove 34 is formed at both axial ends of the inner circumferential rubber 30, extending continuously in the circumferential direction while opening outward in the axial direction. Similarly, the outer circumferential groove 36 is formed at both axial ends of the outer circumferential rubber 32, extending in the circumferential direction while opening outward in the axial direction. In this embodiment, the bottom surfaces of both the inner circumferential groove 34 and the outer circumferential groove 36 are approximately semi-circular concave surfaces. The axial end of the cylindrical portion 20 of the intermediate sleeve 18 extends into the area between the inner circumferential groove 34 and the outer circumferential groove 36 in the radial direction. In this embodiment, the axial depth dimension of the inner circumferential groove 34 is slightly smaller than that of the outer circumferential groove 36, but the depth dimensions of the inner circumferential groove 34 and the outer circumferential groove 36 may be the same, or the outer circumferential groove 36 may be smaller.

[0034] The main rubber elastic body 16 has cavities 38, 38 formed in the portions corresponding to the straight portions 24, 24 of the slits 22 of the intermediate sleeve 18. The cavities 38 open to the axial end faces of the main rubber elastic body 16 and extend linearly in the axial direction. In this embodiment, the cavities 38 have a substantially rhombic cross-sectional shape in the state before the outer cylindrical member 14 is reduced in diameter, and are flattened rhombic cross-sectional shapes in which the diagonals in the vertical direction are longer than the diagonals in the horizontal direction. Part of the cavities 38 are located within the straight portions 24 of the slits 22, and extend to the inner and outer circumferences beyond the cylindrical portion 20 of the intermediate sleeve 18. A cavity 38 corresponding to one axial (front) straight section 24 opens on one axial end face of the main rubber elastic body 16 and extends partway along the axial direction of the main rubber elastic body 16. Similarly, a cavity 38 corresponding to the other axial (rear) straight section 24 opens on the other axial end face of the main rubber elastic body 16 and extends partway along the axial direction of the main rubber elastic body 16. In this embodiment, the cavity 38 does not reach the far end of the straight section 24 in the axial direction (the end on the intermediate section 28 side), and a rear wall rubber 40 is provided behind the cavity 38.

[0035] The main rubber elastic body 16 includes an intermediate rubber 42 that fills the intermediate portion 28 of the slit 22 of the intermediate sleeve 18. As shown in Figure 10A, the intermediate rubber 42 extends axially in the intermediate portion 28, and both axial ends are fixed to the intermediate sleeve 18, connecting the axial portions on both sides of the intermediate portion 28 in the intermediate sleeve 18 in the axial direction. As shown in Figure 9, there are cavities 38, 38 on both sides of the intermediate rubber 42 in the circumferential direction. The intermediate rubber 42 is formed integrally and continuously with the inner circumferential rubber 30 and the outer circumferential rubber 32 in the radial direction, and the inner circumferential rubber 30 and the outer circumferential rubber 32 are integrally connected to each other by the intermediate rubber 42. Note that when molding the main rubber elastic body 16, it is difficult to insert a mold into the intermediate portion 28 which extends circumferentially, and it is difficult to form spaces such as cavities 38, 38 in the intermediate portion 28 relative to the straight portions 24, 24. Therefore, the intermediate rubber 42 is formed to fill the intermediate portion 28.

[0036] After the main rubber elastic body 16 is vulcanized, the outer cylindrical member 14 is subjected to a diameter reduction process (drawing process) to form the cylindrical vibration damping device 10 shown in Figures 1 to 5. In the cylindrical vibration damping device 10, the main rubber elastic body 16, which is positioned radially between the inner shaft member 12 and the outer cylindrical member 14, is pre-compressed radially by the diameter reduction process of the outer cylindrical member 14. This reduces tensile stress caused by thermal shrinkage after molding of the main rubber elastic body 16, thereby improving the durability of the main rubber elastic body 16. The method for reducing the diameter of the outer cylindrical member 14 is not particularly limited, but a diameter reduction method such as eight-way drawing can be employed, in which the outer cylindrical member 14 is pressed inward by a jig that is pressed against the outer surface of the outer cylindrical member 14 in eight radial directions to reduce its diameter.

[0037] When the outer cylindrical member 14 undergoes diameter reduction deformation, the outer circumferential rubber 32 positioned between the outer cylindrical member 14 and the intermediate sleeve 18 is compressed radially, improving the durability of the outer circumferential rubber 32. Furthermore, the elasticity (reaction force against compression) of the outer circumferential rubber 32 exerts a force in the diameter reduction direction on the cylindrical portion 20 of the intermediate sleeve 18. Since a portion of the cylindrical portion 20 in the circumferential direction is divided by the slit 22, in response to the input in the diameter reduction direction, the width of the straight portions 24,24 in the slit 22 narrows, as shown in Figure 10B. As a result, the diameter reduction deformation of the outer cylindrical member 14 also causes the cylindrical portion 20 of the intermediate sleeve 18 to undergo diameter reduction deformation, and the inner circumferential rubber 30 positioned between the intermediate sleeve 18 and the inner shaft member 12 is also compressed radially, improving the durability of the inner circumferential rubber 30. In this way, the formation of the slit 22 in the intermediate sleeve 18 allows both the outer rubber 32 and the inner rubber 30 of the main rubber elastic body 16 to be pre-compressed, thereby advantageously improving durability.

[0038] As the intermediate sleeve 18 is reduced in diameter, the cavities 38, 38 formed in the portions corresponding to the straight sections 24, 24 deform so that their circumferential width decreases, as shown in Figures 1, 4, and 5. Because cavities 38, 38 are formed in the straight sections 24, 24, the force required for the diameter reduction deformation of the intermediate sleeve 18 is reduced compared to when the straight sections 24, 24 are filled with rubber. This is because, when the straight sections 24, 24 are filled with rubber, the compression spring of the rubber acts as a resistance force against the diameter reduction of the intermediate sleeve 18, requiring a greater force. In this embodiment, even after the diameter reduction of the intermediate sleeve 18, the narrowed cavities 38, 38 remain open at the axial end faces. However, for example, the inner walls of both circumferential sides of each cavity 38 may be in close contact with each other so that the cavities 38, 38 substantially disappear.

[0039] Furthermore, the intermediate rubber 42 formed in the middle portion 28 of the slit 22 undergoes shear deformation as both axial ends are displaced relative to each other in the circumferential direction during the diameter reduction deformation of the intermediate sleeve 18. As a result, the shear spring of the intermediate rubber 42, which has a smaller spring constant than the compression spring, acts as a resistance force against the diameter reduction of the intermediate sleeve 18. Therefore, the intermediate sleeve 18 can be reduced in diameter with less force compared to when the compression spring of the intermediate rubber 42 acts as a resistance force. In this embodiment, a back wall rubber 40, which is integrally formed with the main rubber elastic body 16, is provided in the axial depth of each of the cavities 38, 38. The back wall rubber 40 is integrally continuous with the intermediate rubber 42 and extends circumferentially outward from the intermediate rubber 42 to the inner surface of the side wall of the straight portion 24. However, since one back wall rubber 40 and the other back wall rubber 40 are located at positions separated from each other in the axial direction, when the diameter of the intermediate sleeve 18 is reduced, the intermediate rubber 42 is not purely compressed in the circumferential direction, and a small resistance force acts due to the shear spring of the intermediate rubber 42.

[0040] The cylindrical vibration isolation device 10 has an intermediate sleeve 18 extending in the circumferential direction between the inner shaft member 12 and the outer cylindrical member 14, which allows for a larger ratio to the spring force perpendicular to the axis and the spring force relative to the torsion in the circumferential (torsional) direction. In other words, the cylindrical vibration isolation device 10, by having the intermediate sleeve 18, makes it easier to achieve both high dynamic spring force perpendicular to the axis and low dynamic spring force in the torsional direction.

[0041] Incidentally, the intermediate sleeve 18 is subjected to blast treatment as a pretreatment to improve the adhesion of the main rubber elastic body 16 before the molding of the main rubber elastic body 16. Blasting treatment is a process that improves the adhesive strength of the main rubber elastic body 16 by spraying a blasting material (abrasive) onto the surface of the intermediate sleeve 18, thereby removing the coating on the surface of the intermediate sleeve 18 and roughening the surface.

[0042] In this blasting process, multiple intermediate sleeves 18 may be processed at once. For example, if the blasting equipment is equipped with a drum (processing container) capable of accommodating multiple intermediate sleeves 18, the drum can be rotated or otherwise moved to move the multiple intermediate sleeves 18 within the drum, and blasting material can be sprayed onto these intermediate sleeves 18, thereby allowing the multiple intermediate sleeves 18 to be blasted at once.

[0043] However, in the case of a conventional intermediate sleeve structure with a slit extending linearly in the axial direction, if a large number of intermediate sleeves are to be blast-treated all at once as described above, other intermediate sleeves 18 may get caught in the slits of one intermediate sleeve and remain in an overlapping state, resulting in the blast treatment not reaching the overlapping portion. As a result, variations may occur in the adhesive strength of the main rubber elastic body 16 to the intermediate sleeve, or the main rubber elastic body 16 may partially peel off from the intermediate sleeve.

[0044] Therefore, the intermediate sleeve 18 of this embodiment has a structure that includes straight sections 24, 24 that do not directly overlap the slits 22 in an axial view. As a result, even if another intermediate sleeve 18 (cylindrical section 20) enters the slit 22 of the intermediate sleeve 18, the other intermediate sleeve 18 will not continuously enter both straight sections 24, 24, and the other intermediate sleeve 18 will easily detach from the slit 22. Thus, by preventing the overlap caused by the entry of another intermediate sleeve 18 into the slit 22 of the intermediate sleeve 18 from being maintained, and by ensuring that the blast treatment covers the entire intermediate sleeve 18, it is possible to stabilize the adhesion of the main rubber elastic body 16 to the intermediate sleeve 18 through stable pretreatment of the intermediate sleeve 18.

[0045] Furthermore, even if the insertion of one intermediate sleeve 18 into the slit 22 of the intermediate sleeve 18 is maintained, the other intermediate sleeve 18 is only able to insert into one of the straight sections 24 of the slit 22, and does not insert across both straight sections 24, 24. Therefore, compared to a conventional intermediate sleeve structure in which the other intermediate sleeve can insert across the entire slit, the overlapping area of ​​the intermediate sleeves 18, 18 is reduced, and the area not covered by blast treatment due to the overlap is narrowed, thereby reducing variations in adhesive strength, etc. For the sake of ease of understanding, the intermediate sleeve 18 and the other intermediate sleeve 18 have been described separately, but the above-mentioned intermediate sleeve 18 and the other intermediate sleeve 18 are both substantially the same and have the structure according to this embodiment.

[0046] Figures 11 to 13 show a cylindrical vibration isolation device 50 as a second embodiment of the present invention, in the state before the outer cylindrical member 14 is reduced in diameter. The cylindrical vibration isolation device 50 includes an intermediate sleeve 52. In the following description, components and parts that are substantially the same as those in the first embodiment may be denoted by the same reference numerals as in the first embodiment, and their description may be omitted.

[0047] The intermediate sleeve 52 includes a cylindrical portion 54 which is substantially cylindrical in shape overall. The cylindrical portion 54 is divided circumferentially by a slit 56 in a part of the circumferential direction. As shown in Figure 14A, the slit 56 includes straight portions 24, 24 that extend linearly in the axial direction from both axial ends of the cylindrical portion 54. In this embodiment, the straight portions 24, 24 are positioned at different locations in the circumferential direction of the cylindrical portion 54, similar to the first embodiment, but the circumferential separation distance of the cylindrical portion 54 is shorter and they are closer to each other in the circumferential direction compared to the first embodiment. As a result, the axially inner ends of the straight portions 24, 24 are directly connected without being connected via an intermediate portion 28 that extends in the circumferential direction as in the first embodiment.

[0048] Cavities 38, 38 are formed in the parts of the main rubber elastic body 16 that correspond to the straight sections 24, 24. Since the straight sections 24, 24 of the slit 56 are adjacent in the circumferential direction, the cavities 38, 38 formed at the positions corresponding to each straight section 24 are adjacent to each other in the circumferential direction.

[0049] A thin film of intermediate rubber 58 is formed between adjacent portions at the back of the cavities 38, 38. The intermediate rubber 58 is a rubber membrane formed in the gap between the molds used to form the cavities 38, 38 during the molding of the main rubber elastic body 16, and is integrally formed with the main rubber elastic body 16. In this embodiment, the intermediate rubber 58 is formed to connect the back wall rubbers 40, 40 formed at the back of the cavities 38, 38.

[0050] Then, after the main rubber elastic body 16 is vulcanized, the outer cylindrical member 14 is subjected to a diameter reduction process, and as shown in Figure 14B, the intermediate sleeve 52 is deformed and reduced in diameter so that the circumferential width dimension of the straight portions 24, 24 of the slit 56 becomes smaller. When the intermediate sleeve 52 is reduced in diameter, the intermediate rubber 58 undergoes shear deformation as both its axial ends are displaced relative to each other in the circumferential direction. The intermediate rubber 58 in this embodiment, which is in the form of a thin film, may rupture as it deforms.

[0051] The same effects as in the first embodiment can be obtained with a cylindrical vibration damper 50 equipped with such an intermediate sleeve 52. Furthermore, in the cylindrical vibration damper 50 of this embodiment, since the circumferential thickness dimension of the intermediate rubber 58 is reduced, the force resisting the reduction in diameter due to the elasticity of the intermediate rubber 58 is further reduced when the diameter of the intermediate sleeve 52 is reduced, so that the intermediate sleeve 52 can be effectively deformed to reduce its diameter with less force.

[0052] Figures 15 to 17 show a cylindrical vibration isolation device 60 as a third embodiment of the present invention, in the state before the outer cylindrical member 14 is reduced in diameter. The cylindrical vibration isolation device 60 includes an intermediate sleeve 62.

[0053] The intermediate sleeve 62 includes a cylindrical portion 64 which is substantially cylindrical in shape overall. The cylindrical portion 64 is divided circumferentially by a slit 66 in a part of the circumferential direction. As shown in Figure 18A, the slit 66 includes straight portions 24, 24 that extend linearly in the axial direction from both axial ends of the cylindrical portion 64. In this embodiment, the straight portions 24, 24 are formed at mutually different positions in the circumferential direction of the cylindrical portion 64, but there is a portion that directly overlaps in an axial view, and the slit 66 extends linearly through this overlapping portion in the axial direction. The circumferential width (overlap allowance) d of the overlapping portion of the straight portions 24, 24 in an axial view is smaller than the radial thickness dimension of the cylindrical portion 64 of the intermediate sleeve 62. Therefore, even if the cylindrical portion 64 of one intermediate sleeve 62 enters the slit 66 of the intermediate sleeve 62 from one of the straight portions 24, the other intermediate sleeve 62 is prevented from going beyond the connection portion of the straight portions 24, 24 and into the other straight portion 24.

[0054] An intermediate rubber 68 is formed at the connection point of the straight sections 24, 24. In this embodiment, the intermediate rubber 68 is located at the back of each of the straight sections 24, 24, and connects the inner surfaces of the walls on both sides of the slit 66 in the circumferential direction at the connection point of the straight sections 24, 24.

[0055] Then, after the main rubber elastic body 16 is vulcanized, the outer cylindrical member 14 is subjected to a diameter reduction process, and as shown in Figure 18B, the intermediate sleeve 62 is deformed and reduced in diameter so that the circumferential width dimension of the straight portions 24, 24 of the slit 66 becomes smaller. When the intermediate sleeve 62 is reduced in diameter, the intermediate rubber 68 is compressed in the circumferential direction, but since the axial length dimension of the intermediate rubber 68 is sufficiently small, the resistance force due to the compression spring of the intermediate rubber 68 is unlikely to be a problem when the intermediate sleeve 62 is reduced in diameter.

[0056] The same effects as in the first embodiment can be obtained with a cylindrical vibration damper 60 equipped with such an intermediate sleeve 62. As shown in this embodiment, the straight portions 24, 24 of the slit 66 do not necessarily have to be located far apart in the circumferential direction, and even if they partially overlap in the axial view, the same effects can be obtained as long as the overlap allowance is defined so as to restrict the entry of other intermediate sleeves 62 into the slits.

[0057] Figure 19 shows an intermediate sleeve 70 constituting a cylindrical vibration isolation device as a fourth embodiment of the present invention. In this embodiment, only the intermediate sleeve 70 and the intermediate rubber 82, which will be described later, are shown, but other parts of the cylindrical vibration isolation device, which are not shown, can adopt the same structure as in the first embodiment.

[0058] The intermediate sleeve 70 includes a cylindrical portion 72 which is substantially cylindrical in shape overall. The cylindrical portion 72 is divided circumferentially by a slit 74 in a part of the circumferential direction. As shown in Figure 19A, the slit 74 includes straight portions 24, 24 that extend linearly in the axial direction from both axial ends of the cylindrical portion 72. In this embodiment, the straight portions 24, 24 are formed at the same relative positions in the circumferential direction of the intermediate sleeve 70.

[0059] The slit 74 includes an intermediate section 76 that connects the straight sections 24, 24 to each other. The intermediate section 76 includes an axial extension section 78 that extends axially at different circumferential positions from the straight sections 24, 24, and circumferential extension sections 80, 80 that connect the inner ends of the straight sections 24, 24 to both ends of the axial extension section 78. As shown in Figure 19A, the intermediate section 76 has a horizontal U-shape in plan view, and both ends are connected to one of the straight sections 24.

[0060] An intermediate rubber 82 is fixed to the middle portion 76 of the slit 74. The intermediate rubber 82 is integrally formed with the main rubber elastic body (16), which is not shown, and is provided over the entire middle portion 76.

[0061] Then, after the main rubber elastic body (16) is vulcanized, the outer cylindrical member (14) is subjected to a diameter reduction process, and as shown in Figure 19B, the intermediate sleeve 70 is deformed and reduced in diameter so that the circumferential width dimension of the straight portions 24, 24 of the slit 74 becomes smaller. When the intermediate sleeve 70 is reduced in diameter, the intermediate rubber 82 is compressed in the circumferential direction, but if the axial length dimension of the intermediate rubber 82 is made sufficiently small, it is possible to prevent the resistance force due to the compression spring of the intermediate rubber 82 from becoming a problem when the intermediate sleeve 70 is reduced in diameter. In addition, the axial length of the axial extension portion 78 can also be made sufficiently small, and for example, the width dimension of the axial extension portion 78 and / or the width dimension of the circumferential extension portion 80 may be set to be larger than the width dimension of the straight portion 24. Furthermore, the overall shape of the intermediate portion 76 is not limited to a U-shape in front view as exemplified, but may also be an arc shape or the like.

[0062] A cylindrical vibration damping device equipped with such an intermediate sleeve 70 can also achieve the same effects as in the first embodiment. As shown in this embodiment, the straight portions 24, 24 do not necessarily have to be located at mutually different positions in the circumferential direction, and the same effects as in the above embodiment can be achieved as long as the intermediate portion 76 restricts the insertion of other intermediate sleeves 70.

[0063] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, the width dimension of the straight portion 24 of the slit 22 may change in the axial direction. Specifically, for example, the width dimension of the straight portion 24 may gradually increase toward both ends in the axial direction.

[0064] The intermediate portion 28 connecting the straight portions 24, 24 in the slit 22 may extend in the circumferential direction while being inclined in the axial direction, and the inclination angle may change in the circumferential direction.

[0065] The shape of the opening of the cavity 38 formed in the main rubber elastic body 16 is not limited to the roughly rhombic shape shown in the above embodiment, but may also be a roughly circular shape including an ellipse, a roughly rectangular shape, or the like.

[0066] The intermediate rubber formed within the slit is not essential and may not be formed. Furthermore, if an intermediate rubber is formed, it is desirable that it be provided to undergo shear deformation when the intermediate sleeve undergoes diameter reduction deformation. However, as shown in the third and fourth embodiments, there may be a portion that is compressed when the intermediate sleeve undergoes diameter reduction deformation, or the entire rubber may be compressed.

[0067] In the above embodiment, blast treatment was given as an example of a process in which one intermediate sleeve may enter the slit of another intermediate sleeve. However, when performing a process on an intermediate sleeve other than blast treatment, such as spraying adhesive, the process may be designed to suppress the entry of another intermediate sleeve into the slit of another intermediate sleeve. [Explanation of symbols]

[0068] 10. Cylindrical Vibration Isolator (First Embodiment) 12 Inner shaft member 14 Outer cylindrical member 16 Main body rubber elastic body 18 intermediate sleeves 20 Cylindrical part 22 slits 24 Straight section 26 Guide surface 28 Middle section 30 Inner circumference rubber 32 Outer circumference rubber 34. Inner circumference groove 36. Grooves along the outer perimeter 38 Blank 40 Back wall rubber 42 Intermediate rubber 50. Cylindrical Vibration Isolator (Second Embodiment) 52 Intermediate Sleeves 54 Cylindrical part 56 slits 58 Intermediate rubber 60. Cylindrical Vibration Isolator (Third Embodiment) 62 Intermediate Sleeves 64 Cylindrical part 66 slits 68 Intermediate rubber 70 Intermediate sleeve (fourth embodiment) 72 Cylindrical part 74 slits 76 Middle section 78 Axial extension section 80 Circumferential extension part 82 Intermediate rubber

Claims

1. A cylindrical vibration damping device is provided in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, and a cylindrical intermediate sleeve extending circumferentially between the inner shaft member and the outer cylindrical member is fixed to the main rubber elastic body, A slit is formed in a part of the circumferential direction of the aforementioned intermediate sleeve, which penetrates in the axial direction. The ends of the slit are straight sections that extend in the axial direction. The direct overlap of the straight sections on both sides in an axial view is smaller than the radial thickness dimension of the intermediate sleeve. A cylindrical vibration isolation device in which the straight portions on both sides of the slit are formed at mutually different positions in the circumferential direction within the intermediate sleeve.

2. The cylindrical vibration isolation device according to claim 1, wherein the slit has an intermediate portion that connects the straight portions on both sides to each other in the circumferential direction.

3. The cylindrical vibration damping device according to claim 2, wherein an intermediate rubber is provided in the intermediate portion of the slit, connecting the axial portions on both sides of the intermediate sleeve with respect to the intermediate portion.

4. A cylindrical vibration damping device in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, and a cylindrical intermediate sleeve extending circumferentially between the inner shaft member and the outer cylindrical member is fixed to the main rubber elastic body, A slit is formed in a part of the circumferential direction of the aforementioned intermediate sleeve, which penetrates in the axial direction. The ends of the slit are straight sections that extend in the axial direction. The direct overlap of the straight sections on both sides in an axial view is smaller than the radial thickness dimension of the intermediate sleeve. A cylindrical vibration isolation device in which the intermediate portion of the slit, which connects the straight portions at both ends of the slit, is provided at a position different in the circumferential direction from either of the straight portions at both ends of the slit.

5. The outer cylindrical member is a diameter-reduced member, and the outer cylindrical member applies radial pre-compression to the inner rubber on the inner circumference side and the outer rubber on the outer circumference side of the intermediate sleeve that constitutes the main body rubber elastic body, The cylindrical vibration isolation device according to any one of claims 1 to 4, wherein the intermediate sleeve is deformed so that the circumferential width dimension of the straight section becomes smaller.

6. An intermediate sleeve for a cylindrical vibration damping device, comprising a cylindrical portion extending circumferentially between an inner shaft member and an outer cylindrical member in the radial direction, wherein the cylindrical portion is connected to the inner shaft member and the outer cylindrical member by a main rubber elastic body, A slit is formed in a part of the circumferential direction of the cylindrical portion, which penetrates in the axial direction. The ends of the slit are straight sections that extend in the axial direction. The direct overlap of the straight sections on both sides in an axial view is smaller than the radial thickness dimension of the cylindrical section. An intermediate sleeve in which the straight portions on both sides of the slit are formed at mutually different positions in the circumferential direction.

7. An intermediate sleeve for a cylindrical vibration damping device, comprising a cylindrical portion extending circumferentially between an inner shaft member and an outer cylindrical member in the radial direction, wherein the cylindrical portion is connected to the inner shaft member and the outer cylindrical member by a main rubber elastic body, A slit is formed in a part of the circumferential direction of the cylindrical portion, which penetrates in the axial direction. The ends of the slit are straight sections that extend in the axial direction. The direct overlap of the straight sections on both sides in an axial view is smaller than the radial thickness dimension of the cylindrical section. An intermediate sleeve in which the intermediate portion of the slit, which connects the straight portions at both ends of the slit, is provided at a position different in the circumferential direction from either of the straight portions at both ends of the slit.

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