Cylindrical vibration control device

Abstract

To provide a cylindrical vibration control device having a novel structure, capable of achieving desired spring characteristics at high level with an easily manufacturable structure.SOLUTION: In a cylindrical vibration control device 10 in which an inner shaft member 12 and an outer cylindrical member 14 are connected by a body rubber elastic body 16, an intermediate member 26 is arranged radially between the inner shaft member 12 and the outer cylindrical member 14, the intermediate member 26 is fastened to the body rubber elastic body 16, an axial central portion of the intermediate member 26 forms a bulge part 30 whose inner and outer peripheral surfaces protrude outward with respect to both axial end parts, and the intermediate member 26 comprises a wavy portion 36 that forms radial irregularities in the bulge part 30.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a cylindrical vibration isolator that is applied to, for example, a suspension bush of an automobile. [Background technology]

[0002] Conventionally, cylindrical vibration-damping devices that are applied to automobile suspension bushes and the like have been known. For example, as shown in JP 2022-010591 A (Patent Document 1), the cylindrical vibration-damping device has a structure in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body. In addition, the suspension bush of Patent Document 1 has an intermediate member disposed between the inner shaft member and the outer cylindrical member, and the spring characteristics in each direction are adjusted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-010591 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the thickness dimension of the intermediate member changes in the axial central portion so that it becomes thicker toward the center, thereby achieving both a hard spring characteristic in the radial direction and a soft spring characteristic in the prying direction.

[0005] However, in order to obtain such an intermediate part whose thickness dimension changes in the axial direction, special processing is required, such as pressing a metal plate of approximately constant thickness in the thickness direction while changing the amount of pressing, making it difficult to manufacture the intermediate part and, as a result, making it a more expensive part than an intermediate part whose entire thickness dimension is approximately constant.

[0006] An object of the present invention is to provide a cylindrical vibration-isolating device of a novel structure that can realize the desired spring characteristics to a high degree with an easily manufacturable structure. [Means for solving the problem]

[0007] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely illustrative and may be combined with one another as appropriate, and the multiple components described in each embodiment may be recognized and used independently as far as possible, and may also be combined with any of the components described in another embodiment as appropriate. As a result, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0008] The first aspect is a cylindrical vibration-damping device in which an inner axial member and an outer tubular member are connected by a main rubber elastic body, an intermediate member is arranged radially between the inner axial member and the outer tubular member and fixed to the main rubber elastic body, and the axial central portion of the intermediate member is a bulge portion whose inner and outer circumferential surfaces protrude outward more than both axial end portions, and the intermediate member has a wavy portion that creates radial unevenness in the bulge portion.

[0009] In a cylindrical vibration-damping device constructed in accordance with this embodiment, by providing a wavy portion in the bulge portion of the intermediate member, the intermediate member is substantially thickened in the wavy portion, and it is possible to set a stiff radial spring characteristic without significantly changing the thickness dimension of the intermediate member in the bulge portion compared to other portions.

[0010] In a second aspect, in the cylindrical vibration-isolating device described in the first aspect, the thickness dimension of the intermediate member is constant over the entirety.

[0011] According to a cylindrical vibration-damping device constructed according to this embodiment, the intermediate member can be manufactured more easily than when the thickness dimension of the intermediate member is changed in the axial or circumferential direction.

[0012] The third aspect is a cylindrical vibration-damping device described in the first or second aspect, in which the intermediate member is a curved plate extending in the circumferential direction, and a pair of intermediate members are provided that face each other radially.

[0013] In the cylindrical vibration-damping device constructed according to this embodiment, since the intermediate member is plate-shaped, it is possible to easily form, for example, a wavy portion that is uneven in the radial direction by press working. Also, by disposing a pair of intermediate members facing each other in the radial direction, it is possible to obtain high spring characteristics in the radial direction where the intermediate members face each other.

[0014] A fourth aspect is a cylindrical vibration-damping device according to any one of the first to third aspects, wherein the wavy portion is wavy in the axial direction.

[0015] According to a cylindrical vibration-damping device constructed in accordance with this embodiment, the wavy portion has a wavy structure in which the projections and recesses are continuous in the axial direction, making it easier to manufacture an intermediate member having a wavy portion.

[0016] A fifth aspect is a cylindrical vibration-damping device according to any one of the first to third aspects, wherein the wavy portion is wavy in the circumferential direction.

[0017] Like the cylindrical vibration-isolating device constructed according to this embodiment, the wavy portion may have a wavy structure in which the projections and recesses are continuous in the circumferential direction.

[0018] A sixth aspect is a cylindrical vibration-damping device described in any one of the first to fifth aspects, wherein the axial central portion of the inner axial member is a bulging portion whose outer peripheral surface protrudes outward more than both axial end portions, and the inner peripheral surface of the outer axial member has a concave surface that protrudes inward toward the axially outward direction.

[0019] According to a cylindrical vibration-damping device constructed in accordance with this embodiment, in addition to the bulge portion of the intermediate member, a bulge portion of the inner axial member and a concave surface of the outer tubular member are provided, so that when vibration in the twisting direction is input between the inner axial member and the outer tubular member, the shear spring component becomes even more dominant, thereby achieving even lower spring characteristics in the twisting direction. Effect of the Invention

[0020] According to the present invention, in a cylindrical vibration isolation device, it is possible to realize the desired spring characteristics to a high degree with a structure that can be easily manufactured. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view showing a suspension bush according to a first embodiment of the present invention; [Diagram 2] FIG. 2 is a cross-sectional view of the suspension bush shown in FIG. 1, which corresponds to the cross-section II-II of FIG. 3. [Diagram 3] III-III cross section of Figure 2 [Figure 4] FIG. 2 is a perspective view of an intermediate member constituting the suspension bush shown in FIG. [Diagram 5] FIG. 5 is a plan view of the intermediate member shown in FIG. [Figure 6] Cross-sectional view of Fig. 5 taken along the line VI-VI [Figure 7] Cross-sectional view of FIG. 5 taken along the line VII-VII [Figure 8] FIG. 8 is a cross-sectional view showing a suspension bush according to a second embodiment of the present invention, which corresponds to the cross section VIII-VIII of FIG. [Figure 9] IX-IX cross section of Figure 8 [Figure 10] FIG. 9 is a perspective view of an intermediate member constituting the suspension bush shown in FIG. 8 . [Figure 11] 11 is a plan view of the intermediate member shown in FIG. [Figure 12] Sectional view of XII-XII in Fig. 11 [Figure 13] XIII-XIII sectional view of Figure 11 [Figure 14]Sectional view XIV-XIV of Fig. 12 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] 1 to 3 show a suspension bushing 10 for an automobile as a first embodiment of a cylindrical vibration-damping device constructed according to the present invention. The suspension bushing 10 has a structure in which an inner shaft member 12 and an outer cylindrical member 14 are connected by a main rubber elastic body 16. In the following description, as a general rule, the up-down direction refers to the up-down direction in Fig. 2, the front-rear direction refers to the left-right direction in Fig. 2, and the left-right direction refers to the left-right direction in Fig. 3.

[0024] The inner shaft member 12 is a thick-walled, small-diameter cylindrical member, and is a highly rigid member made of, for example, metal or fiber-reinforced synthetic resin. The inner shaft member 12 has shaft end tube portions 18, 18 that extend linearly in the front-rear direction with a substantially constant diameter at both ends in the axial direction. The inner shaft member 12 has a bulge portion 20 that protrudes to the outer periphery at the central portion in the axial direction. The bulge portion 20 is bulged in such a way that the protruding dimension to the outer periphery increases toward the axial center. The bulge portion 20 has an outer peripheral surface that protrudes to the outer periphery more than the shaft end tube portions 18, 18, and has an outer diameter dimension larger than that of the shaft end tube portions 18, 18. In this embodiment, the outer peripheral surface and inner peripheral surface of the bulge portion 20 protrude to the outer periphery more than the outer peripheral surface and inner peripheral surface of the shaft end tube portions 18, 18, and both the inner diameter dimension and the outer diameter dimension of the bulge portion 20 are larger than those of the shaft end tube portions 18, 18.

[0025] The outer cylindrical member 14 is a thin-walled, large-diameter cylinder, and is a high-rigidity member made of metal, fiber-reinforced synthetic resin, or the like, similar to the inner shaft member 12. The outer cylindrical member 14 has a smaller axial length than the inner shaft member 12. The outer cylindrical member 14 has a central cylindrical portion 22 that extends linearly in the front-rear direction with a substantially constant diameter at its axial center. The outer cylindrical member 14 has tapered portions 24, 24 on both sides of the central cylindrical portion 22 in the axial direction that decrease in diameter toward the axial outward direction. The outer cylindrical member 14 has the central cylindrical portion 22 and the tapered portions 24, 24, and is thus bulged in such a way that both the inner and outer circumferential surfaces increase in diameter toward the axial center as a whole, and the inner circumferential surface is a concave surface 25 that inclines inward toward both axial sides. The central cylindrical portion 22 of the outer cylindrical member 14 has a length dimension in the axial direction that is smaller than that of the bulging portion 20 of the inner axial member 12 .

[0026] The inner shaft member 12 is inserted into the inner circumference of the outer tubular member 14, and the inner shaft member 12 and the outer tubular member 14 are connected to each other in the radial direction by the main rubber elastic body 16. The main rubber elastic body 16 is formed in a substantially cylindrical shape, and its inner peripheral surface is vulcanized and bonded to the outer peripheral surface of the inner shaft member 12 including the bulging portion 20, and its outer peripheral surface is vulcanized and bonded to the inner peripheral surface (concave surface 25) of the outer tubular member 14. The outer tubular member 14 may be formed in a cylindrical shape of a substantially constant diameter as a whole when the main rubber elastic body 16 is vulcanized and molded, or tapered portions 24, 24 may be formed at both ends in the axial direction by performing a diameter reduction process after the main rubber elastic body 16 is vulcanized and molded. By reducing the diameter of the outer tubular member 14 after the main rubber elastic body 16 is vulcanized and molded, the tensile stress caused by the thermal contraction of the main rubber elastic body 16 is reduced, and durability can be improved.

[0027] A pair of intermediate members 26, 26 are fixed to the main rubber elastic body 16. As shown in Figs. 4 to 7, the intermediate member 26 is a curved plate-like member that extends in an arc shape that is less than halfway around as a whole, and is made of, for example, metal or fiber-reinforced synthetic resin.

[0028] The intermediate member 26 has straight portions 28, 28 at both axial ends that extend linearly in the axial direction, and a bulge portion 30 that protrudes to the outer periphery between the straight portions 28, 28 in the axial direction. The straight portion 28 has an inner diameter dimension and an outer diameter dimension that are substantially constant in the axial direction. The bulge portion 30 is provided in the axial center portion of the intermediate member 26, and both the inner peripheral surface and the outer peripheral surface protrude outward more than the straight portion 28, so that both the inner diameter dimension and the outer diameter dimension are larger than those of the straight portion 28. The bulge portion 30 has a gradually larger diameter toward the axial center on both axial sides of a wavy portion 36 described later.

[0029] Notches 32, 32 located in the circumferential center are formed on both axial ends of the intermediate member 26. The notches 32 are formed across the straight portion 28 and the axial end of the bulge portion 30, and have a substantially constant circumferential width dimension in the portion formed in the straight portion 28, while the portion formed in the bulge portion 30 has an expanding shape in which the circumferential width dimension increases axially outward.

[0030] A through hole 34 is formed in the bulge portion 30 of the intermediate member 26. The through hole 34 has a substantially circular cross section and penetrates the bulge portion 30 in the radial direction, and in this embodiment, is formed at two locations spaced apart from each other in the circumferential direction.

[0031] The bulge portion 30 of the intermediate member 26 is provided with a wavy portion 36. The wavy portion 36 is provided in the axial center portion of the bulge portion 30, and is formed so as to be wavy in the axial direction by providing radial unevenness continuously in the axial direction. In this embodiment, the concaves and convexities of the wavy portion 36 extend in a substantially constant cross-sectional shape over the entire circumferential length of the intermediate member 26. The wavy portion 36 of this embodiment is shaped such that one concave is provided between two convexities on the outer circumferential surface. In the following description, in the wavy portion 36, the portion whose outer circumferential surface is concave is referred to as a concave portion 38, and the portion whose outer circumferential surface is convex is referred to as a convex portion 40. Therefore, the wavy portion 36 of this embodiment has a concave portion 38 at one location in the axial center, and a convex portion 40 at two locations on both sides of the concave portion 38 in the axial direction. Note that the notches 32, 32 formed at the axial end portion of the intermediate member 26 do not reach the wavy portion 36, and are separated from the wavy portion 36 in the axial direction. Further, the through holes 34 , 34 formed in the axial center portion of the intermediate member 26 penetrate the wavy portion 36 .

[0032] The intermediate member 26 has a substantially constant thickness throughout, including the wavy portion 36. The intermediate member 26 can be obtained, for example, by pressing a flat metal plate. Since the intermediate member 26 has a substantially constant thickness throughout, it can be manufactured more easily than intermediate members whose thickness varies, making it easier to improve mass productivity and prevent costs from increasing. The thickness of the intermediate member 26 can be considered to be substantially constant even if there is a slight difference in thickness due to uneven thickness when forming the wavy portion 36 by pressing or the like.

[0033] The pair of intermediate members 26, 26 are arranged facing each other in the up-down direction, and as shown in Figs. 2 and 3, they are disposed radially between the inner shaft member 12 and the outer tubular member 14, and are vulcanized and bonded to the radially middle portion of the main rubber elastic body 16. The inner and outer circumferential surfaces of the bulge portion 30 of each intermediate member 26 are both covered by the main rubber elastic body 16. In the main rubber elastic body 16, the outer circumferential rubber 42 located on the outer circumferential side of the intermediate members 26, 26 and the inner circumferential rubber 44 located on the inner circumferential side are integrally connected to each other between the circumferential ends of the intermediate members 26, 26 and through holes 34, 34 of each intermediate member 26. As shown in Fig. 1, both axial end faces of the intermediate member 26 composed of the straight portion 28 are exposed to the outside at the axial end faces of the main rubber elastic body 16. Furthermore, the notches 32 of the intermediate member 26 are not filled with the main rubber elastic body 16 , and the main rubber elastic body 16 within the notches 32 is in the form of a thin film that covers the inner surface of the notches 32 .

[0034] The main rubber elastic body 16 fits into the unevenness of the wavy portion 36 provided in the bulge portion 30 of the intermediate member 26. That is, as shown in Fig. 2, the main rubber elastic body 16 is filled in the concave surface (outer peripheral concave surface 46) on the outer circumferential side of the recessed portions 38 of the wavy portion 36, and the main rubber elastic body 16 is filled in the concave surfaces (inner circumferential concave surface 48) on the inner circumferential side of the protruding portions 40, 40.

[0035] The inner circumferential rubber 44 located radially between the inner axial member 12 and the intermediate member 26 is thinnest in the radial direction between the bulging portion 20 of the inner axial member 12 and the recessed portion 38 of the wavy portion 36 of the intermediate member 26. In addition, the outer circumferential rubber 42 located radially between the outer tubular member 14 and the intermediate member 26 is thinnest in the radial direction between the central tubular portion 22 of the outer tubular member 14 and the protruding portions 40, 40 of the wavy portion 36 of the intermediate member 26.

[0036] The suspension bush 10 constructed as above is mounted on a vehicle by, for example, attaching the inner shaft member 12 to the vehicle body (not shown) and attaching the outer tubular member 14 to a suspension arm (not shown), thereby connecting the suspension arm to the vehicle body in a vibration-proof manner. The inner shaft member 12 is attached to the vehicle body by, for example, a bolt member inserted through the center hole, and the outer tubular member 14 is attached to the suspension arm by press-fitting the central tubular portion 22 into a mounting hole of the suspension arm.

[0037] When mounted on the vehicle in this manner, the suspension bush 10 achieves both low spring characteristics against vibration input in the twisting direction and high spring characteristics against vibration input in the up and down direction.

[0038] That is, since the bulge portion 30 is provided in the axial center portion of the intermediate member 26, low spring characteristics can be obtained due to the shear spring component of the main rubber elastic body 16 when a prying force is applied so that the inner shaft member 12 and the outer tubular member 14 tilt relatively up and down. This leads to an improvement in the ride comfort of the vehicle.

[0039] In particular, in this embodiment, a bulge-like protruding portion 20 that protrudes outward is provided in the axial center portion of the inner shaft member 12, and the outer cylindrical member 14 as a whole is formed into a bulge-like shape that protrudes outward, and the inner peripheral surface of the outer cylindrical member 14 is formed into a concave surface 25. Therefore, when the inner shaft member 12 and the outer cylindrical member 14 are subjected to a prying displacement, the shear spring component of the main rubber elastic body 16 becomes more dominant, and an even lower spring characteristic in the prying direction is realized.

[0040] On the other hand, when vibration is input to the suspension bush 10 in the vertical direction, the intermediate member 26 has a wavy portion 36, which is uneven in the radial direction, in its axial center portion, so that the main rubber elastic body 16 is substantially thinned in the vertical direction, thereby realizing high spring characteristics. That is, the main rubber elastic body 16 located on the inner and outer periphery of the wavy portion 36 of the intermediate member 26 has both the portion that enters the outer peripheral concave surface 46 of the recess 38 and the portion that enters the inner peripheral concave surfaces 48, 48 of the protrusions 40, 40 restrained from deformation by the wavy portion 36. Therefore, the main rubber elastic body 16 within the outer peripheral concave surface 46 and the inner peripheral concave surfaces 48, 48 can be regarded as substantially a rigid body. 2, in the intermediate member 26, the surface passing through the inner circumferential ends of the recesses 38 (the surface passing through the opening ends of the inner circumferential concave surfaces 48, 48) in the wavy portion 36 is the substantial inner circumferential surface, and the surface passing through the outer circumferential ends of the protrusions 40, 40 (the surface passing through the opening ends of the outer circumferential concave surface 46) is the substantial outer circumferential surface, so that the substantial thickness dimension can be increased without significantly changing the actual thickness dimension in the axial direction. As a result, the radial thickness dimension of the main rubber elastic body 16 on the inner and outer circumferential sides of the wavy portion 36 is substantially smaller, and the spring characteristics of the suspension bush 10 against vibration input in the up and down direction are made harder, thereby improving durability and improving running stability due to the high spring characteristics.

[0041] Furthermore, by providing the intermediate member 26 with the corrugated portion 36, the inner circumferential rubber 44 located on the inner circumferential side of the intermediate member 26 is thin-walled in the radial direction between the bulging portion 20 of the inner shaft member 12 and the recessed portion 38 of the corrugated portion 36, and the outer circumferential rubber 42 located on the outer circumferential side of the intermediate member 26 is thin-walled in the radial direction between the central tubular portion 22 of the outer tubular member 14 and the protruding portions 40, 40 of the corrugated portion 36. Therefore, when vibration in the vertical direction is input between the inner shaft member 12 and the outer tubular member 14, high spring characteristics are exerted in the inner circumferential rubber 44 between the bulging portion 20 and the recessed portion 38, and high spring characteristics are exerted in the outer circumferential rubber 42 between the central tubular portion 22 and the protruding portions 40, 40, so that the spring characteristics of the suspension bush 10 can be set to be hard in the vertical direction.

[0042] The substantial vertical thickness dimension of the corrugated portion 36 of the intermediate member 26, in other words, the substantial thickness dimension in the vertical direction of the main rubber elastic body 16, can be set by adjusting the height dimension of the projections and recesses of the corrugated portion 36. Therefore, the spring characteristics in the vertical direction of the suspension bushing 10 can be easily adjusted by the height dimension of the projections and recesses of the corrugated portion 36.

[0043] The wavy portion 36 is provided only in the center of the intermediate member 26, and substantial thickening of the intermediate member 26 due to constraint by the main rubber elastic body 16 is avoided on both axial sides of the wavy portion 36. Therefore, at the axial ends of the main rubber elastic body 16 where compression springiness is likely to become a problem when a prying input is applied, the substantial radial thickness dimension of the main rubber elastic body 16 is ensured to be large, making it easier to obtain low spring characteristics.

[0044] 8 and 9 show a suspension bushing 60 according to a second embodiment of the present invention. The suspension bushing 60 includes a pair of intermediate members 62, 62. In the following description, members and parts that are substantially the same as those in the first embodiment are given the same reference numerals in the drawings and description thereof will be omitted.

[0045] As shown in Figs. 10 to 14, the intermediate member 62 is in the shape of a curved plate extending in the circumferential direction. The intermediate member 62 has a wavy portion 64 in the bulge portion 30 constituting the central portion in the axial direction. As shown in Figs. 9 and 12, the wavy portion 64 is formed so as to be wavy in the circumferential direction by radial unevenness that continues in the circumferential direction. The wavy portion 64 in this embodiment is formed by four recesses 66, 66, 66, 66 that are concave on the outer circumferential surface and three protrusions 68, 68, 68 that are convex on the outer circumferential surface, which are alternately continued in the circumferential direction. The wavy portion 64 has unevenness that continues smoothly in the circumferential direction, and the inner and outer circumferential surfaces are formed of smoothly curved surfaces.

[0046] 8 and 9, the pair of intermediate members 62, 62 are vulcanization bonded to the main rubber elastic body 16 radially between the inner shaft member 12 and the outer cylindrical member 14. The pair of intermediate members 62, 62 are disposed facing each other in the up-down direction, and their circumferential ends are spaced apart from each other.

[0047] A main rubber elastic body 16 (outer peripheral rubber 42) is fixed to an outer peripheral concave surface 70 of each recess 66 in the intermediate member 62, and the main rubber elastic body 16 is filled in the recess on the outer peripheral side of the recess 66. Similarly, a main rubber elastic body 16 (inner peripheral rubber 44) is fixed to an inner peripheral concave surface 72 of each protrusion 68 in the intermediate member 26, and the main rubber elastic body 16 is filled in the recess on the inner peripheral side of the protrusion 68.

[0048] In the suspension bush 60 constructed according to this embodiment, similarly to the first embodiment, low spring characteristics in the prying direction and high spring characteristics in the up-down direction are both achieved.

[0049] That is, with respect to vibration input in the prying direction, a low spring characteristic can be obtained due to the shear spring component of the main rubber elastic body 16 by providing the bulge portion 30 in the axial center portion of the intermediate member 62. In this embodiment, as in the first embodiment, the bulge portion 20 of the inner axial member 12 and the concave surface 25 of the outer tubular member 14 are used in combination with the bulge portion 30 of the intermediate member 62, so that a low spring characteristic with respect to vibration input in the prying direction is more advantageously realized.

[0050] On the other hand, when vibration is input in the vertical direction, the main rubber elastic body 16 is substantially thinned by the wavy portion 64 provided on the intermediate member 62, so that high spring characteristics can be obtained. That is, in the main rubber elastic body 16, the portion of the wavy portion 64 that enters the outer peripheral concave surface 70 of the concave portion 66 and the portion of the wavy portion 64 that enters the inner peripheral concave surface 72 of the convex portion 68 are both restrained from deformation by the wavy portion 64. As a result, the substantial vertical thickness dimension of the main rubber elastic body 16 that is allowed to deform when vibration is input is made small in the axial center portion where the wavy portion 64 is located, and high spring characteristics in the vertical direction are realized. Note that the concave portion 66 in this embodiment is a portion that is concave-shaped on the outer peripheral surface of the wavy portion 64, similar to the concave portion 38 in the first embodiment, and the convex portion 68 is a portion that is convex-shaped on the outer peripheral surface of the wavy portion 64, similar to the convex portion 40 in the first embodiment.

[0051] Furthermore, in the main rubber elastic body 16, the vertical thickness dimension of the inner circumferential rubber 44 is made smaller between the vertical opposing surfaces of the bulging portion 20 of the inner shaft member 12 and the two recessed portions 66, 66 located at the circumferential center, and the vertical thickness dimension of the outer circumferential rubber 42 is made smaller between the vertical opposing surfaces of the central tubular portion 22 of the outer tubular member 14 and the protruding portion 68 located at the circumferential center. Therefore, when vibration is input in the vertical direction, high spring characteristics can be obtained by the portion of the inner circumferential rubber 44 located between the vertical portions of the bulging portion 20 and the recessed portions 66, 66 and the portion of the outer circumferential rubber 42 located between the vertical portions of the central tubular portion 22 and the protruding portions 68, and the stiff spring characteristics in the vertical direction improve driving stability.

[0052] In short, the intermediate member 62 having the wavy portion 64 in which radial irregularities are provided continuously in the circumferential direction as shown in this embodiment can be expected to have the same effects as the intermediate member 26 having the wavy portion 36 in which radial irregularities are provided continuously in the axial direction as shown in the first embodiment.

[0053] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific description. For example, the intermediate member is not limited to a pair of plates, but may be a cylindrical member that is continuous in the circumferential direction, or may be a C-shaped ring.

[0054] The thickness dimension of the intermediate member is desirably constant throughout, but may vary, for example, in the axial or circumferential direction, and does not necessarily have to be constant.

[0055] The concave and convex portions of the wavy portion are not necessarily limited to a shape extending in the circumferential or axial direction, but may be, for example, a shape extending in an oblique direction inclined with respect to the circumferential and axial directions.

[0056] The number of projections and recesses constituting the wavy portion 36 is not particularly limited, and it is sufficient that at least one recess and one projection are provided to form a wavy shape. The wavelength and amplitude of the wavy portion 36 may be substantially constant or may vary. The bulge portion 30 of the intermediate member 26 may have inner and outer diameters larger than those of both axial end portions at least in the projections 40 of the wavy portion 36, and for example, depending on the depth of the recesses 38, the outer diameter of the recesses 38 of the bulge portion 30 may be smaller than the outer diameter of both axial end portions. Furthermore, the straight portion 28, the notches 32, the through holes 34, etc. of the intermediate member 26 are not essential.

[0057] The bulging portion 20 of the inner shaft member 12 is not essential, and may have, for example, a substantially constant diameter over the entire length. The bulging portion 20 of the inner shaft member 12 may be formed of a separate member, and for example, an inner shaft member having a bulging portion can be obtained by attaching or fastening a separate bulging portion to the outer circumferential surface of a pipe-shaped member. The inner circumferential surface of the outer tubular member 14 does not necessarily need to be a concave surface 25, and may have, for example, a substantially constant diameter over the entire length and a straight tubular inner surface.

[0058] The present invention is preferably applied to suspension bushings as illustrated in the above embodiment, but can also be applied to cylindrical vibration-damping devices in general in which inputs perpendicular to the axis and in the prying direction are expected, and can also be applied to, for example, bushings for engine mounts and torque rods. [Explanation of symbols]

[0059] 10 Suspension bush (cylindrical vibration isolator, first embodiment) 12 Inner shaft member 14 Outer cylindrical member 16 Main rubber elastic body 18 Shaft end tube part 20 Bulge 22 Central cylinder part 24 Tapered section 25 concave surface 26 Intermediate parts 28 Straight section 30 Bulge 32 Notch 34 Through hole 36 Wavy part 38 Recess 40 Convex 42 Outer rubber 44 Inner rubber 46 Concave outer periphery 48 Inner concave surface 60 Suspension bush (cylindrical vibration isolator, second embodiment) 62 Intermediate parts 64 Wavy part 66 Recess 68 Convex 70 Concave outer periphery 72 Inner concave surface

Claims

1. In a cylindrical vibration-damping device in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, an intermediate member is disposed radially between the inner shaft member and the outer cylindrical member, and the intermediate member is fixed to the main rubber elastic body; The intermediate member has an axial center portion that is a bulge portion having an inner peripheral surface and an outer peripheral surface that protrude outward more than both axial end portions, The intermediate member is a cylindrical vibration-damping device having a wavy portion that forms radial irregularities at the bulge portion.

2. 2. The cylindrical vibration isolator according to claim 1, wherein the thickness of said intermediate member is constant throughout.

3. The intermediate member is a curved plate extending in a circumferential direction, 3. The cylindrical vibration isolating device according to claim 1, wherein a pair of said intermediate members are provided so as to face each other in the radial direction.

4. 3. A cylindrical vibration isolator according to claim 1, wherein the wavy portion is wavy in the axial direction.

5. 3. A cylindrical vibration-damping device according to claim 1, wherein the wavy portion is wavy in the circumferential direction.

6. The axial center portion of the inner shaft member is a bulging portion whose outer circumferential surface protrudes outward more than both axial end portions, 3. The cylindrical vibration-damping device according to claim 1, wherein the inner peripheral surface of the outer cylindrical member is provided with a concave surface that protrudes inwardly and axially outward.

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