Cylindrical vibration isolation device and torque rod using the same

Abstract

To provide a cylindrical vibration isolator having a novel structure which is reducible in a size and weight by setting a rubber volume of a main body rubber elastic body according to an input load.SOLUTION: In a cylindrical vibration isolator 60 having a structure in which a cylindrical main-body rubber elastic body 42 is arranged at an internal periphery of a cylindrical part 22 of an outer member 12, the main-body rubber elastic body 42 comprises a rubber long-length part 48 whose dimension in an axial direction is large, and a rubber short-length part 50 whose dimension in the axial direction is small in positions which are displaced from each other in a circumferential direction. The cylindrical part 22 of the outer member 12 is set as an outer long-length part 24 whose dimension in the axial direction of a region corresponding to the rubber long-length part 48 in the circumferential direction is large, and an outer short-length part 26 whose dimension in the axial direction of a region corresponding to the rubber short-length part 50 in the circumferential direction is small.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a cylindrical vibration isolator provided with a cylindrical main body rubber elastic body and a torque rod provided with the cylindrical vibration isolator.

Background Art

[0002] Conventionally, for example, a cylindrical vibration isolator is provided at the end of a torque rod attached to a vehicle. As disclosed in Japanese Patent Application Laid-Open No. 2001-200892 (Patent Document 1), the cylindrical vibration isolator includes a cylindrical main body rubber elastic body disposed on the inner circumference of a cylindrical portion of an outer member composed of a rod body of the torque rod or the like. Then, the vibration load between the inner shaft member disposed in an inserted state on the inner circumference of the main body rubber elastic body and the outer member attached to the outer peripheral surface of the main body rubber elastic body is reduced by the internal friction of the main body rubber elastic body or the like, thereby exerting a vibration isolation effect.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a general cylindrical vibration isolator as disclosed in Patent Document 1, the axial length of the main body rubber elastic body is substantially constant in the circumferential direction.

[0005] However, for example, in a cylindrical vibration isolator used for a torque rod, there is a difference in the magnitude of the input load between the inner side and the outer side in the length direction of the rod body. Therefore, on the inner side where the input load is small, the rubber volume of the main body rubber elastic body is larger than necessary, which may contribute to the enlargement of the cylindrical vibration isolator. This was the same not only for the cylindrical vibration isolator for the torque rod but also for all cylindrical vibration isolators in which the magnitude of the input load varies in the circumferential direction.

[0006] The problem to be solved by the present invention is to provide a cylindrical vibration isolation device with a novel structure that can be made smaller and lighter by setting the rubber volume of the main body's rubber elastic material according to the input load.

[0007] Furthermore, the present invention also aims to provide a torque rod equipped with the cylindrical vibration damping device described above. [Means for solving the problem]

[0008] 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.

[0009] The first embodiment is a cylindrical vibration damping device having a structure in which a cylindrical main body rubber elastic body is arranged on the inner circumference of the cylindrical portion of an outer member, wherein the main body rubber elastic body is provided with a long rubber portion with a large axial dimension and a short rubber portion with a small axial dimension, positioned offset from each other in the circumferential direction, and the cylindrical portion of the outer member has an outer long portion with a large axial dimension in the part corresponding to the long rubber portion in the circumferential direction, and an outer short portion with a small axial dimension in the part corresponding to the short rubber portion in the circumferential direction.

[0010] According to the cylindrical vibration isolation device with a structure conforming to this embodiment, by arranging the long rubber section in the circumferential portion where the input load to the main rubber elastic body is large, and arranging the short rubber section in the circumferential portion where the input load to the main rubber elastic body is small, it is possible to achieve miniaturization and weight reduction of the main rubber elastic body while ensuring the load-bearing capacity of the main rubber elastic body against input loads.

[0011] The cylindrical portion of the outer member is provided with an outer long portion corresponding to the long rubber portion of the main rubber elastic body and an outer short portion corresponding to the short rubber portion of the main rubber elastic body. This enables miniaturization and weight reduction of the cylindrical vibration isolation device, including the outer member.

[0012] The second embodiment is a cylindrical vibration isolation device described in the first embodiment, wherein the axial dimension of the main body rubber elastic body changes continuously in the circumferential direction from the long rubber portion to the short rubber portion.

[0013] According to the cylindrical vibration isolation device with a structure conforming to this embodiment, the formation of steps at the axial end face of the main rubber elastic body is avoided compared to the case where the axial dimension of the main rubber elastic body changes in steps. Therefore, stress concentration at the axial end face of the main rubber elastic body is prevented when a vibration load is applied, thereby improving the durability of the main rubber elastic body.

[0014] The third embodiment is a cylindrical vibration damping device described in the first or second embodiment, wherein one of the long rubber portion and the short rubber portion are provided on both radial sides of the main body rubber elastic body.

[0015] According to the cylindrical vibration isolation device constructed in accordance with this embodiment, when the magnitude of the input load differs on both radial sides, the load-bearing capacity of the main rubber elastic body can be ensured on both radial sides, while miniaturization and weight reduction can be achieved by providing a short rubber section on the radial side with the smaller input load.

[0016] The fourth embodiment is a cylindrical vibration isolation device described in any one of the first to third embodiments, wherein the axial dimension of the cylindrical portion changes continuously in the circumferential direction from the outer long portion to the outer short portion.

[0017] According to the cylindrical vibration isolation device constructed in this embodiment, it is possible to provide an outer long section and an outer short section with mutually different axial dimensions while preventing the formation of a step on the axial end face of the cylindrical section. Furthermore, by adopting this embodiment in combination with a second embodiment in which the axial dimension of the main rubber elastic body changes continuously in the circumferential direction from the rubber long section to the rubber short section, it is possible to efficiently achieve miniaturization and weight reduction of the cylindrical vibration isolation device by corresponding the change in the axial dimension of the main rubber elastic body with the change in the axial dimension of the cylindrical section.

[0018] The fifth embodiment is a cylindrical vibration damping device described in any one of the first to fourth embodiments, wherein the main body rubber elastic body is fixed to the outer circumferential surface of the inner shaft member, and a positioning part is provided for positioning the inner shaft member and the cylindrical portion of the outer member in the circumferential direction.

[0019] According to the cylindrical vibration isolation device with a structure conforming to this embodiment, when it is necessary to provide the main rubber elastic body in a specific orientation in the circumferential direction due to the presence of a long rubber portion and a short rubber portion, the main rubber elastic body can be provided in a specific orientation in the circumferential direction by positioning the inner shaft member to which the main rubber elastic body is fixed relative to the cylindrical portion by a positioning portion.

[0020] The sixth aspect is a cylindrical vibration damping device comprising a main rubber elastic body interposed between an inner shaft member and a cylindrical portion of an outer member, wherein the axial dimension of the main rubber elastic body is gradually reduced from one radial dimension to the other.

[0021] According to the cylindrical vibration isolation device constructed in accordance with this embodiment, for example, by setting the axial dimension of the main rubber elastic body to be large in one radial direction where the input load to the main rubber elastic body is large, and setting the axial dimension of the main rubber elastic body to be small in the other radial direction where the input load to the main rubber elastic body is small, it is possible to achieve miniaturization and weight reduction of the main rubber elastic body while ensuring the load-bearing capacity of the main rubber elastic body against the input load.

[0022] By gradually changing the axial dimension of the main rubber elastic body from one radial direction to the other, stress concentration during load input can be prevented at the axial end faces of the main rubber elastic body, and the durability of the main rubber elastic body can be improved.

[0023] The seventh aspect is the cylindrical vibration isolator described in any one of the first to sixth aspects, wherein a flange-shaped retaining portion that overlaps the axial end face of the cylindrical portion is provided at the axial end of the main rubber elastic body.

[0024] According to the cylindrical vibration isolator having the structure according to this aspect, the detachment of the main rubber elastic body from the cylindrical portion is prevented by the engagement between the retaining portion and the cylindrical portion.

[0025] The eighth aspect is a torque rod provided with the cylindrical vibration isolator described in the first aspect, wherein the outer member is a rod body, and the main rubber elastic body is attached to the cylindrical portion provided at an end in the rod length direction of the rod body, and the rubber long portion of the main rubber elastic body and the outer long portion of the cylindrical portion are located outside the rod body in the rod length direction, and the rubber short portion of the main rubber elastic body and the outer short portion of the cylindrical portion are located inside the rod body in the rod length direction.

[0026] According to the torque rod having the structure according to this aspect, by arranging the rubber long portion and the outer long portion outside the rod body in the rod length direction where the input load becomes large, the load-bearing performance against vibration input can be ensured. Also, by arranging the rubber short portion and the outer short portion inside the rod body in the rod length direction where the input load becomes small in the torque rod, the rod body can be miniaturized at the cylindrical portion, and weight reduction is thereby achieved.

Advantages of the Invention

[0027] According to the present invention, in the cylindrical vibration isolator and the torque rod using the same, the rubber volume of the main rubber elastic body can be set according to the input load, thereby achieving miniaturization and weight reduction. [Brief explanation of the drawing]

[0028] [Figure 1] Perspective view of a torque rod as a first embodiment of the present invention [Figure 2] Bottom view of the torque rod shown in Figure 1 [Figure 3] Front view of the torque rod shown in Figure 1 [Figure 4] Right side view of the torque rod shown in Figure 1. [Figure 5] This is a cross-sectional view of the right end of the torque rod shown in Figure 1, which corresponds to the VV section in Figure 3. [Figure 6] Perspective view of the second bushing that constitutes the torque rod shown in Figure 1. [Figure 7] Plan view of the second bush shown in Figure 6 [Figure 8] Figure 6 shows the bottom view of the second bush. [Figure 9] Right side view of the second bush shown in Figure 6. [Figure 10] Left side view of the second bush shown in Figure 6. [Figure 11] Front view of the second bush shown in Figure 6 [Figure 12] Figure 7 shows the cross-sectional view between XII and XII. [Figure 13] Figure 12: Cross-sectional view of XIII-XIII [Modes for carrying out the invention]

[0029] Embodiments of the present invention will be described below with reference to the drawings.

[0030] Figures 1 to 5 show a torque rod 10 as a first embodiment of the present invention. The torque rod 10 has a structure in which a first bush 14 and a second bush 16 are attached to both ends of a rod body 12 which serves as an outer member. In the following description, the front-rear direction refers to the up-and-down direction in Figure 2, the left-right direction refers to the left-right direction in Figure 2, and the up-and-down direction refers to the up-and-down direction in Figure 3.

[0031] The rod body 12 is made of a highly rigid material such as iron or aluminum alloy, or fiber-reinforced synthetic resin. The rod body 12 integrally comprises a rod portion 18 extending in the left-right direction, a first cylindrical portion 20 provided at one end (left end) of the rod portion 18, and a second cylindrical portion 22 provided at the other end (right end) of the rod portion 18.

[0032] In this embodiment, the rod portion 18 is rectangular in shape, either as a column or a rectangular plate, with its vertical dimension being greater than its horizontal dimension. However, the specific shape of the rod portion 18 is not particularly limited; for example, it may be cylindrical or polygonal in shape extending in the left-right direction.

[0033] The first cylindrical portion 20 has a roughly cylindrical shape that extends vertically, with its vertical dimension being approximately the same as that of the rod portion 18, and its front-to-back dimension being larger than that of the rod portion 18. The rod portion 18 and the first cylindrical portion 20 are smoothly continuous on both the front and back surfaces, and the thickness dimension in the front-to-back direction increases toward the outer side of one side in the longitudinal direction of the rod body 12 (the left side in Figure 2).

[0034] The second cylindrical portion 22 has a roughly cylindrical shape extending in the front-rear direction, and its vertical dimension is slightly larger than the vertical dimension of the rod portion 18. The rod portion 18 and the second cylindrical portion 22 are smoothly continuous on both the upper and lower surfaces, and the thickness dimension in the vertical direction increases toward the other outer side (right side in Figure 3) along the length of the rod body 12. The second cylindrical portion 22 has a smaller diameter than the first cylindrical portion 20.

[0035] As shown in Figure 2, the second cylindrical portion 22 has an axial dimension, which is the front-to-back dimension, that is continuously decreasing from one radial side to the other, substantially coinciding with the length direction of the rod portion 18. As a result, the second cylindrical portion 22 has an outer elongated portion 24 with a larger axial dimension on one radial side and an outer shorted portion 26 with a smaller axial dimension on the other radial side. In this embodiment, one radial side of the second cylindrical portion 22 is on the rod portion 18 side (inside the rod body 12), and the other radial side of the second cylindrical portion 22 is on the opposite side from the rod portion 18 (outside the rod body 12). Furthermore, the second cylindrical portion 22 has outer inclined surfaces 28, 28 at both axial ends that are inclined so that they approach each other from one radial side to the other, and has a symmetrical shape with respect to an axial plane passing through the center in the front-to-back direction.

[0036] A first bush 14 is attached to the first cylindrical portion 20 of the rod body 12. The first bush 14 has a structure in which the first inner shaft member 30 and the intermediate sleeve 32 are elastically connected by a first main body rubber elastic body 34.

[0037] The first inner shaft member 30 is a rigid member made of metal or synthetic resin, and has a substantially cylindrical shape with bolt holes that penetrate in the vertical direction. The intermediate sleeve 32 is cylindrical in shape, with an inner diameter larger than the outer diameter of the first inner shaft member 30, and is arranged to surround the first inner shaft member 30 at a distance. The first main body rubber elastic body 34 is substantially cylindrical in shape overall, with its inner circumferential surface vulcanized and bonded to the outer circumferential surface of the first inner shaft member 30, and its outer circumferential surface vulcanized and bonded to the inner circumferential surface of the intermediate sleeve 32. In addition, the first main body rubber elastic body 34 has an outer cutout portion 36 and an inner cutout portion 38 that penetrate through the first bush 14 in the axial direction (perpendicular to the plane of the paper in Figure 2). The outer curb portion 36 is shorter in circumferential length than the inner curb portion 38, with the circumferential end of the outer curb portion 36 located inward in the front-rear direction from the first inner shaft member 30, and the circumferential end of the inner curb portion 38 located outward in the front-rear direction from the first inner shaft member 30. With the formation of such an outer curb portion 36 and an inner curb portion 38, the first main body rubber elastic body 34 is shaped like a pair of arms extending to both sides in the front-rear direction, and extending with an inclination to the left as it goes outward on both sides in the front-rear direction.

[0038] The first bush 14 is attached to the rod body 12 by press-fitting and fixing the intermediate sleeve 32 into the first cylindrical portion 20 of the rod body 12. Furthermore, by providing a positioning structure that positions the circumferential orientation of the first bush 14 relative to the first cylindrical portion 20, the first bush 14 can be easily assembled in the appropriate orientation relative to the first cylindrical portion 20.

[0039] A second bush 16 is attached to the second cylindrical portion 22 of the rod body 12. As shown in Figures 6 to 13, the second bush 16 has a structure in which a second main body rubber elastic body 42 is vulcanized and bonded to the outer circumferential surface of a second inner shaft member 40, which serves as an inner shaft member.

[0040] The second inner shaft member 40 is a rigid member made of metal, synthetic resin, or the like, and is cylindrical in shape overall. As shown in Figures 11 and 13, the second inner shaft member 40 has a pair of flat surfaces 44, 44 on its outer circumferential surface. The flat surfaces 44, 44 extend substantially parallel to each other and are arranged opposite each other in the vertical direction. The outer diameter of the second inner shaft member 40 is partially reduced in the vertical direction where the flat surfaces 44, 44 are provided, and these flat surfaces 44, 44 constitute the width across flats.

[0041] The lower flat portion 44 is provided with a projection 46 that protrudes downward. The projection 46 is provided at the end of the lower flat portion 44 in the circumferential direction of the second inner shaft member 40, and extends continuously along the entire axial length of the second inner shaft member 40 with a substantially constant cross-sectional shape. The projection 46 has a tapered mountain shape that narrows towards the tip of the projection. By providing the projection 46, the circumferential width dimension of the lower flat portion 44 of the second inner shaft member 40 is smaller than that of the upper flat portion 44.

[0042] As shown in Figures 6 to 10 and Figures 12 and 13, the second main body rubber elastic body 42 is cylindrical in shape overall, and its inner circumferential surface is fixed to the outer circumferential surface of the second inner shaft member 40. As shown in Figures 7 to 10, the axial dimension L (see Figure 7) of the second main body rubber elastic body 42 changes continuously in the circumferential direction from one side to the other, gradually decreasing. As a result, one side of the second main body rubber elastic body 42 is a long rubber portion 48 with a large axial dimension, and the other side is a short rubber portion 50 with a small axial dimension. In this embodiment, the axial dimension of the second main body rubber elastic body 42 changes with a substantially constant rate of change in the circumferential direction, but the rate of change of the axial dimension of the second main body rubber elastic body 42 does not have to be constant in the circumferential direction. In this embodiment, the center of the long rubber portion 48 and the center of the short rubber portion 50 are at substantially the same position in the axial direction of the second main body rubber elastic body 42.

[0043] The second main body rubber elastic body 42 has relief grooves 52, 52 at both axial ends, and the diameter of the grooves at both axial ends is smaller than that of the axial central portion. The relief grooves 52 are provided continuously around the entire circumference, opening to the outer surface. The bottom surface of the relief grooves 52 has a curved shape that becomes larger in diameter towards both axial sides. The relief grooves 52 extend circumferentially, inclined inward in the axial direction from the long rubber portion 48 to the short rubber portion 50. The groove width dimension (axial dimension) of the relief grooves 52 is approximately constant in the circumferential direction.

[0044] Flange-shaped retaining portions 54 are provided on both axial sides of the second main body rubber elastic body 42. The retaining portions 54 have an outer diameter larger than the inner diameter of the mounting hole for the second cylindrical portion 22 of the rod body 12, and the axial inner surface of the retaining portion 54 is a stepped surface that extends perpendicular to the axis so as to overlap with the opening end surface of the mounting hole. In this embodiment, the retaining portion 54 has approximately the same outer diameter as the second main body rubber elastic body 42 before assembly into the mounting hole, but is an annular shape with a larger diameter than the axial end of the second main body rubber elastic body 42 where the relief groove 52 is provided, and a stepped end surface 58 is formed by protruding outward from the axial end of the second main body rubber elastic body 42. The stepped end surface 58 extends annularly inclined axially inward from the long rubber portion 48 toward the short rubber portion 50 in the circumferential direction. The retaining portions 54 are positioned axially outward relative to the second main body rubber elastic body 42. In this embodiment, the second main body rubber elastic body 42 and the retaining portion 54 are integrally formed in a continuous manner in the axial direction, and the retaining portions 54, 54 are provided connected to the axial ends of the second main body rubber elastic body 42, which have been reduced in diameter by the relief grooves 52, 52. In this embodiment, the groove width dimension of the relief groove 52 is substantially constant over the entire circumference and is provided at an inclination so as to be substantially parallel to the axial end face of the second main body rubber elastic body 42.

[0045] As shown in Figure 5, the second main body rubber elastic body 42 is inserted into the second cylindrical portion 22 of the rod body 12, and its outer surface is pressed against the inner surface of the second cylindrical portion 22. In this way, the second bush 16 is attached to the second cylindrical portion 22 of the rod body 12 without adhesive, and the rod body 12 and the second bush 16 constitute the cylindrical vibration damping device 60 of this embodiment. In the cylindrical vibration damping device 60, the second main body rubber elastic body 42 is interposed between the second inner shaft member 40 and the second cylindrical portion 22.

[0046] In this embodiment, the second main body rubber elastic body 42 is compressed radially in the second cylindrical portion 22 by the mounting of the second bush 16 to the second cylindrical portion 22, and as shown in Figure 5, the relief grooves 52, 52 are filled with rubber, and the concave shape of the relief grooves 52, 52 has almost disappeared. In this way, the relief grooves 52, 52 have the function of providing a space that allows deformation of the second main body rubber elastic body 42, thereby adjusting the spring characteristics of the second main body rubber elastic body 42 attached to the second cylindrical portion 22 without making it excessively stiff. Furthermore, because the relief grooves 52, 52 are provided adjacent to the axially inward side of the retaining portions 54, 54, the strain caused by the deformation of the second main body rubber elastic body 42 is less likely to be transmitted to the retaining portions 54, 54, and as will be described later, the retaining portions 54, 54 are appropriately superimposed on the outer inclined surfaces 28, 28, which are the axial end faces of the second cylindrical portion 22.

[0047] When assembling the second bush 16 to the second cylindrical portion 22, for example, the rod body 12 is set in one assembly jig, and the second inner shaft member 40 of the second bush 16 is set in the other assembly jig, and the second bush 16 is assembled to the rod body 12 by these assembly jigs. In an assembly process using such assembly jigs, the occurrence of mis-setting, where the second bush 16 is set in the wrong orientation relative to the other assembly jig, is avoided. That is, the second inner shaft member 40, which is set in the other assembly jig, has a two-sided width structure with flat portions 44, 44 and a projection 46, so it cannot be set in the other assembly jig in any orientation other than the predetermined orientation. Therefore, when assembling the second bush 16 to the second cylindrical portion 22 of the rod body 12 using the assembly jigs, the second bush 16 can be assembled in the correct orientation relative to the rod body 12. Thus, in the second bush 16 of this embodiment, the positioning portion that positions the second inner shaft member 40 and the second cylindrical portion 22 in the circumferential direction is composed of flat portions 44, 44 and a projection 46.

[0048] The second bush 16 is oriented circumferentially with respect to the second cylindrical portion 22 such that the long rubber portion 48 of the second main body rubber elastic body 42 is located on the outer side (right side) in the rod length direction of the rod body 12, and the short rubber portion 50 is located on the inner side (left side) in the rod length direction of the rod body 12. Therefore, in the circumferential direction of the second cylindrical portion 22 and the second main body rubber elastic body 42, the long rubber portion 48 of the second main body rubber elastic body 42 is positioned relative to the outer long portion 24 of the second cylindrical portion 22, and the short rubber portion 50 of the second main body rubber elastic body 42 is positioned relative to the outer short portion 26 of the second cylindrical portion 22. In short, the outer long portion 24 is positioned on the outer circumference side of the long rubber portion 48, and the outer short portion 26 is positioned on the outer circumference side of the short rubber portion 50.

[0049] The retaining portions 54, 54, which are integrally formed with the second main body rubber elastic body 42, are inclined to be substantially parallel to each of the axial end faces of the second cylindrical portion 22 and are superimposed on each of the axial end faces of the second cylindrical portion 22. The locking of the retaining portions 54 with the axial end faces of the second cylindrical portion 22 prevents the second bush 16 from coming out of the second cylindrical portion 22. In this embodiment, retaining portions 54 are arranged on both axial sides of the second cylindrical portion 22, preventing the second bush 16 from coming out of the second cylindrical portion 22 on both axial sides.

[0050] The torque rod 10, with its structure as described above, connects the vehicle body and the power unit by having the first inner shaft member 30 of the first bush 14 and the second inner shaft member 40 of the second bush 16 fixed to either the vehicle body or the power unit, thereby receiving the torque reaction force of the power unit.

[0051] When the torque rod 10 is mounted on a vehicle, the load acting on the second cylindrical portion 22 (torque reaction force of the power unit) is small on the rod portion 18 side, which is the inner side of the rod body 12 in the rod length direction, and large on the opposite side of the rod body 12, which is the outer side of the rod body 12 in the rod length direction. In this embodiment, the second main body rubber elastic body 42 is provided with a long rubber portion 48 with a large axial dimension on the outer side in the rod length direction, and a short rubber portion 50 with a small axial dimension on the inner side in the rod length direction. This allows for a rubber volume that can withstand the input load while achieving miniaturization and weight reduction of the second main body rubber elastic body 42.

[0052] In this embodiment, the second cylindrical portion 22 into which the second main body rubber elastic body 42 is fitted includes an outer long portion 24 corresponding to the rubber long portion 48 and an outer short portion 26 corresponding to the rubber short portion 50. This allows for overall holding of the outer circumferential surface of the second main body rubber elastic body 42, while the outer short portion 26 reduces the size and weight of the second cylindrical portion 22 and, consequently, the rod body 12.

[0053] The second main body rubber elastic body 42 has inclined ends in the axial direction, and its axial dimension changes continuously in the circumferential direction from the long rubber portion 48 to the short rubber portion 50. Therefore, even if the long rubber portion 48 and the short rubber portion 50 have mutually different axial dimensions, there are no shapes on the axial end faces of the second main body rubber elastic body 42 that are prone to stress concentration, such as steps, thus preventing a decrease in the durability of the second main body rubber elastic body 42 due to stress concentration during input.

[0054] Similarly, the second cylindrical portion 22 of the rod body 12 has outer inclined surfaces 28, 28 at both axial ends, and its axial dimension changes continuously in the circumferential direction from the outer long portion 24 to the outer short portion 26. As a result, there are no areas on the axial end faces of the second cylindrical portion 22 where stress concentration such as steps is likely to occur, thus preventing a decrease in the durability of the second cylindrical portion 22 due to stress concentration during input.

[0055] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, in the above embodiment, a structure in which one long rubber portion 48 and one short rubber portion 50 are provided was illustrated, but at least one of the long rubber portion 48 and the short rubber portion 50 may be provided in multiple quantities. For example, when the input load differs in two perpendicular directions, the long rubber portion 48 may be provided on both sides in the perpendicular direction where the input load is large, and the short rubber portion 50 may be provided on both sides in the perpendicular direction where the input load is small.

[0056] The outer long portion 24 and the outer short portion 26 may be provided in multiples of at least one of them. Preferably, the outer long portion 24 and the outer short portion 26 are provided in correspondence with the rubber long portion 48 and the rubber short portion 50. For example, if there are two rubber long portions 48 and two rubber short portions 50, it is desirable that there be two outer long portions 24 and two outer short portions 26.

[0057] The arrangement of the long rubber portion 48 and the short rubber portion 50 in the circumferential direction of the main rubber elastic body is not particularly limited, as long as they are offset from each other in the circumferential direction. Similarly, the arrangement of the long outer portion 24 and the short outer portion 26 in the circumferential direction of the cylindrical portion is not particularly limited, as long as they are offset from each other in the circumferential direction.

[0058] In the above embodiment, one relief groove 52 was formed at each of the axial ends of the second main body rubber elastic body 42, but the embodiment is not limited to this configuration. That is, the relief grooves are set appropriately considering the compression ratio and rubber material when the second main body rubber elastic body 42 is installed, and for example, relief grooves are not essential, and multiple relief grooves may be provided. Furthermore, the position and size of the relief grooves can also be set arbitrarily, and instead of or in addition to the relief grooves, the outer circumferential surface of the second main body rubber elastic body may be inclined so that the outer diameter of the second main body rubber elastic body gradually decreases from the axial center toward both ends.

[0059] In the above embodiment, both axial ends of the second main body rubber elastic body 42 were inclined axially inward from the long rubber portion 48 to the short rubber portion 50. However, for example, only one axial end of the second main body rubber elastic body 42 may be inclined axially inward from the long rubber portion 48 to the short rubber portion 50, while the other axial end may be non-inclined and located at a substantially constant axial position over its entire circumference. Similarly, only one axial end face of the cylindrical portion of the outer member may be the outer inclined surface 28.

[0060] For example, the long rubber portion 48 may extend circumferentially with a constant axial dimension, and the short rubber portion 50 may extend circumferentially with a constant axial dimension smaller than that of the long rubber portion 48, and the axial dimension of the main rubber elastic body may change in a stepped manner at the connection portion of the circumferential ends of the long rubber portion 48 and the short rubber portion 50. Similarly, the tubular portion of the outer member may also change in a stepped manner at the connection portion of the circumferential ends of the long outer portion 24 and the short outer portion 26.

[0061] In the above embodiment, the second main body rubber elastic body 42, which is the main rubber elastic body, was continuous around its entire circumference. However, the main body rubber elastic body only needs to be cylindrical as a whole, and may be partially divided in the circumferential direction by, for example, a rib that penetrates in the axial direction.

[0062] In the above embodiment, the main rubber elastic body was bonded to the second inner shaft member 40, which is the inner shaft member, and non-adhesively fitted into the second cylindrical portion 22, which is the cylindrical portion of the outer member. However, for example, the inner shaft member may be non-adhesively fitted into the central hole of the cylindrical main rubber elastic body, or the cylindrical portion may be bonded to the outer surface of the main rubber elastic body. Furthermore, as with the first bush 14 in the above embodiment, the intermediate sleeve fixed to the outer surface of the main rubber elastic body can also be press-fitted and fixed into the cylindrical portion.

[0063] The positioning section is not limited to a two-sided structure with flat sections 44, 44 and a projection 46. For example, the main rubber elastic body may be positioned circumferentially by arranging multiple flat sections 44 unevenly in the circumferential direction. It is also possible to use a display for relative alignment in the circumferential direction, such as an arrow or a recognizable mark like a bump or groove, as the positioning section. For example, a mechanism that detects such a display using a sensing means such as a camera and aligns it can also be used.

[0064] The structure of the first bush 14 in the above embodiment is merely illustrative and not particularly limiting. Specifically, for example, the first bush may be a fluid-filled type that utilizes the flow action of a fluid sealed inside. Also, for example, the first bush may not have an intermediate sleeve, and the outer circumferential surface of the first main body rubber elastic body 34 may be attached to the inner circumferential surface of the first cylindrical portion 20 by adhesive or not. Furthermore, although the above embodiment shows an example in which the cylindrical vibration isolation device 60 according to the present invention is provided only at one end of the rod body 12, for example, the cylindrical vibration isolation device 60 according to the present invention can also be provided at both ends of the rod body 12.

[0065] In the above embodiment, an example was shown in which the cylindrical vibration damping device according to the present invention was applied to the torque rod of an automobile. However, the cylindrical vibration damping device according to the present invention is not limited to torque rods, and can be suitably applied to, for example, suspension bushings, power unit mounts, etc. When the cylindrical vibration damping device is used for a rod other than a torque rod, the outer member is not limited to a longitudinal shape like the rod body 12, but may be cylindrical in shape, for example, with the entire structure constituting a cylindrical part, or it may be configured such that mounting parts or separate brackets for attachment to a vehicle body, etc., are provided on the outer circumferential surface of the cylindrical part. [Explanation of symbols]

[0066] 10 Torque Rod 12. Rod body (outer component) 14 First Bush 16. Second bushing (cylindrical vibration isolation device) 18 Rod section 20 First cylindrical part 22 Second cylindrical part (cylindrical part) 24 Outer long section 26 Outer short section 28 Outer Inclined Surface 30 First inner shaft member 32 intermediate sleeves 34. First main body rubber elastic body 36. Outer edge 38 Inner corner 40 Second inner shaft member (inner shaft member) 42. Second main body rubber elastic body (main body rubber elastic body) 44. Flat section (positioning section) 46. ​​Protrusion (positioning part) 48 Rubber long section 50 Rubber Short Section 52 Relief groove 54 Retaining part 58 Stepped end face 60 cylindrical vibration isolation device

Claims

1. A cylindrical vibration damping device having a structure in which a cylindrical main body rubber elastic body is disposed between an inner shaft member and a cylindrical portion of an outer member, In the aforementioned main body rubber elastic body, a long rubber portion with a large axial dimension and a short rubber portion with a smaller axial dimension are provided at positions offset from each other in the circumferential direction, where they directly connect the inner shaft member and the cylindrical portion in the radial direction. A cylindrical vibration isolation device in which the cylindrical portion of the outer member has a long outer portion with a large axial dimension in the part corresponding to the long rubber portion in the circumferential direction, and a short outer portion with a small axial dimension in the part corresponding to the short rubber portion in the circumferential direction.

2. The cylindrical vibration damping device according to claim 1, wherein the axial dimension of the main body rubber elastic body changes continuously in the circumferential direction from the long rubber portion to the short rubber portion.

3. The cylindrical vibration damping device according to claim 1 or 2, wherein one of the long rubber portion and the short rubber portion are provided on both radial sides of the main body rubber elastic body.

4. The cylindrical vibration isolation device according to claim 1 or 2, wherein the axial dimension of the cylindrical portion changes continuously in the circumferential direction from the outer long portion to the outer short portion.

5. The main body rubber elastic material is fixed to the outer circumferential surface of the inner shaft member. The cylindrical vibration isolation device according to claim 1 or 2, which is provided with a positioning unit for positioning the inner shaft member and the cylindrical portion of the outer member in the circumferential direction.

6. A cylindrical vibration damping device having a structure in which a cylindrical main body rubber elastic body is arranged on the inner circumference of the cylindrical portion of an outer member, The aforementioned main body rubber elastic body is provided with a long rubber portion with a large axial dimension and a short rubber portion with a small axial dimension, positioned circumferentially offset from each other. The cylindrical portion of the outer member is configured such that the part corresponding to the long rubber portion in the circumferential direction has a larger axial dimension, and the part corresponding to the short rubber portion in the circumferential direction has a smaller axial dimension, A cylindrical vibration damping device is provided, wherein a flange-shaped retaining portion is integrally attached to the main body of the rubber elastic body on the axial outer side of the rubber elastic body, and is superimposed on the axial end face of the cylindrical portion.

7. A cylindrical vibration damping device comprising a main body rubber elastic body interposed between an inner shaft member and a cylindrical portion of an outer member, The main body of the rubber elastic material has an axial dimension that gradually decreases from one radial direction to the other. A cylindrical vibration damping device is provided, wherein a flange-shaped retaining portion is integrally attached to the main body of the rubber elastic body on the axial outer side of the main body of the rubber elastic body, and is superimposed on the axial end face of the cylindrical portion.

8. A cylindrical vibration damping device having a structure in which a cylindrical main body rubber elastic body is arranged on the inner circumference of the cylindrical portion of an outer member, The aforementioned main body rubber elastic body is provided with a long rubber portion with a large axial dimension and a short rubber portion with a small axial dimension, positioned circumferentially offset from each other. A torque rod equipped with a cylindrical vibration damping device, wherein the cylindrical portion of the outer member has a long outer portion with a larger axial dimension in the circumferential direction, and a short outer portion with a smaller axial dimension in the circumferential direction, the portion corresponding to the short rubber portion. The outer member is the rod body, and the rubber elastic body is attached to the cylindrical portion provided at the end of the rod body in the length direction of the rod. A torque rod in which the long rubber portion of the main rubber elastic body and the long outer portion of the cylindrical part are located on the outside in the rod length direction of the rod body, and the short rubber portion of the main rubber elastic body and the short outer portion of the cylindrical part are located on the inside in the rod length direction of the rod body.

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