Dynamic damper

Abstract

This invention provides a novel dynamic damper structure that can be easily attached to the object to be damped and that can suppress adverse effects on damping performance due to unintended displacement of the mass member. [Solution] The dynamic damper 10 is attached to a vibration-damping target 82 via a bracket 16, in which shaft members 28, 28 inserted into a plurality of mounting holes 22, 22 of a mass member 12 are connected to the mass member 12 by connecting rubber elastic bodies 32, 32, and the mass member 12 is elongated in the direction in which the plurality of mounting holes 22, 22 are aligned and has a symmetrical shape in the direction in which the plurality of mounting holes 22, 22 are aligned, and the bracket 16 comprises a fixing part 56 which is fixed to the vibration-damping target 82 by a fixing member 98 which is common with the mounting member 86 of the vibration isolation device 84, and a shaft connecting part 54 which protrudes from the fixing part 56 in a direction intersecting the direction in which the plurality of mounting holes 22, 22 are aligned and connects the plurality of shaft members 28, 28.

Description

Technical Field

[0001] The present invention relates to a dynamic damper that is attached to a vibration damping target of a vehicle and reduces the vibration of the vibration damping target.

Background Art

[0002] Conventionally, as one means for reducing vibration transmitted from a power unit to a vehicle body, for example, an additional dynamic damper may be provided. As described in, for example, Japanese Utility Model Laid-Open No. 6-080043 (Patent Document 1), the dynamic damper has a structure in which a plurality of through holes are formed in a mass member, a core member is disposed in the through holes, and an inner peripheral surface of the through hole and an outer peripheral surface of the core member are connected by a rubber elastic body.

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 Patent Document 1, the core member is attached to the vibration damping target via a bracket. The bracket is attached to the vibration damping target by, for example, bolts or the like. However, the dynamic damper is generally retrofitted according to the vibration state of the vibration damping target, and it is necessary to perform post-processing such as cutting on the vibration damping target in order to provide an attachment portion for the dynamic damper, which tends to complicate the work.

[0005] In addition, in the structure in which a bracket as shown in FIG. 3 of Patent Document 1 extends in the arrangement direction of a plurality of through holes and is attached to the vibration damping target, the mass member may be displaced such as unintended vibration. Therefore, it has been required to make the displacement of the mass member more stable and stably exhibit the intended vibration damping effect.

[0006] The problem to be solved by the present invention is to provide a dynamic damper with a novel structure that can be easily attached to a vibration-damping target and can suppress adverse effects on vibration damping performance due to unintended displacement of the mass member. [Means for solving the problem]

[0007] 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.

[0008] The first embodiment is a dynamic damper in which a mass member is provided with a plurality of mounting holes arranged parallel to each other, a shaft member is inserted into each of the plurality of mounting holes, the mass member and the plurality of shaft members are interconnected by a connecting rubber elastic body, and the shaft members are attached to a vibration-damping object via a bracket, wherein the mass member is elongated in the direction of the arrangement of the plurality of mounting holes and has a symmetrical shape in the direction of the arrangement of the plurality of mounting holes, and the bracket comprises a fixing part which is fixed to the vibration-damping object by a fixing member which is common to the mounting member for the vibration-damping object in a vibration-damping device that supports the vibration-damping object, and a shaft connecting part which protrudes from the fixing part in a direction intersecting the direction of the arrangement of the plurality of mounting holes and connects the plurality of shaft members to each other.

[0009] According to the dynamic damper structure in this embodiment, the bracket's fixing portion is attached to the vibration-damping object together with the mounting member by a fixing member common to the mounting member of the vibration-damping device that supports the vibration-damping object. Therefore, the dynamic damper can be added additionally without requiring, for example, design changes or post-processing to attach the fixing portion to the vibration-damping object.

[0010] Furthermore, in the bracket, the direction in which the axial connecting portion that connects multiple axial members to each other extends from the fixed portion to which the vibration-damping target is attached is perpendicular to the direction in which the multiple mounting holes are aligned. As a result, the mass member is supported in a balanced manner by each support portion of the mass member, which is composed of multiple connecting rubber elastic bodies and axial members, making it difficult for unintended vibrations of the mass member to occur. In particular, even when the direction in which the multiple mounting holes are aligned is the longitudinal direction of the mass member, stable support of the mass member is more easily achieved.

[0011] The second embodiment is a dynamic damper described in the first embodiment, wherein the vibration isolation device is a cylindrical vibration isolation device in which an inner cylinder member and an outer cylinder member, which are bottomed cylindrical mounting members, are connected by a main rubber elastic body, and the fixing portion of the bracket inserted into the inner cylinder member is fastened together with the bottom wall of the inner cylinder member with a bolt which is a fixing member and fixed to the vibration isolation target.

[0012] According to the dynamic damper structured in this embodiment, the dynamic damper can be easily attached to the vibration damping target by fastening the bracket's fixing portion together with the inner cylindrical member of the cylindrical vibration damping device using bolts.

[0013] Since the bracket's fixing portion is inserted into a bottomed cylindrical inner member and then bolted to the object to be damped, it is expected that the fixing portion and the inner cylindrical member will be positioned to some extent before bolting, which will facilitate the bolting process.

[0014] The third embodiment is a dynamic damper as described in the second embodiment, wherein the fixing portion of the bracket inserted into the inner cylinder member of the vibration isolation device protrudes from the circumferential wall of the inner cylinder member on the side opposite to the bottom wall of the inner cylinder member.

[0015] According to the dynamic damper structure in this embodiment, when bolts are inserted from the fixing side of the bracket and bolted to the member to be damped, the bolt tightening work becomes easier.

[0016] The fourth embodiment is a dynamic damper described in any one of the first to third embodiments, wherein the fixed portion has a flat outer surface shape, and the shaft connecting portion extends from the long outer end of the fixed portion.

[0017] According to the dynamic damper structure of this embodiment, for example, it becomes easier to arrange multiple fastening structures in the longitudinal direction at the fixed portion. Furthermore, because the axial connection portion extends from the outer peripheral end on the longitudinal side of the fixed portion, it becomes easier to secure space on the axial side of the fixed portion, making it easier to avoid interference between the axial connection portion or the mass member attached to the axial connection portion via a bushing and other members. Therefore, even when there is no space around the vibration-damping target due to other members, it becomes easier to additionally attach the dynamic damper to the vibration-damping target.

[0018] The fifth embodiment is a dynamic damper described in any one of the first to fourth embodiments, wherein the shaft connecting portion is plate-shaped and extends in a direction perpendicular to the shaft member, and an axial stopper is configured to limit the amount of relative displacement of the shaft member in the axial direction with respect to the mass member by contact between the shaft connecting portion and the opening peripheral edge of the mounting hole in the mass member via a buffer rubber, and the tip side of the shaft connecting portion that protrudes from the fixing portion is located on the inner circumference side of the opening peripheral edge of the mounting hole.

[0019] In a dynamic damper structured according to this embodiment, the shaft connection portion and, consequently, the bracket can be made lighter compared to a case where the shaft connection portion has a constant outer diameter and an axial stopper is formed around the entire circumference.

[0020] In the resonance mode where the mass member elastically supported by the shaft connecting portion at a plurality of locations in the longitudinal direction swings and tilts with respect to the shaft connecting portion, the axial displacement amount of the mass member is more likely to be larger at both ends in the longitudinal direction than at both ends in the short direction. Therefore, while effectively restricting the displacement of the mass member by the axial stopper in the longitudinal direction of the mass member, in the short direction of the mass member, by reducing the shaft connecting portion on the protruding tip side from the fixing portion, the weight of the bracket can be reduced.

Advantages of the Invention

[0021] According to the present invention, in the dynamic damper, it can be easily attached to the vibration control target, and the adverse influence on the vibration control performance due to the unintended displacement of the mass member can be suppressed.

Brief Description of the Drawings

[0022] [Figure 1] Perspective view showing a dynamic damper as a first embodiment of the present invention [Figure 2] Plan view of the dynamic damper shown in FIG. 1 [Figure 3] Bottom view of the dynamic damper shown in FIG. [Figure 4] Front view of the dynamic damper shown in FIG. 1 [Figure 5] Rear view of the dynamic damper shown in FIG. 1 [Figure 6] Left side view of the dynamic damper shown in FIG. 1 [Figure 7] Cross-sectional view taken along line VII-VII of FIG. 2 [Figure 8] Cross-sectional view taken along line VIII-VIII of FIG. 4 [Figure 9] Cross-sectional view taken along line IX-IX of FIG. 4 [Figure 10] Perspective view of the bracket constituting the dynamic damper shown in FIG. 1 [Figure 11] Perspective view showing the bracket of FIG. 10 from another angle [Figure 12] Cross-sectional view showing the vehicle mounting state of the dynamic damper shown in FIG. 1, corresponding to the cross-section XII-XII in FIG. 13 [Figure 13] Figure 12: Cross-sectional view of XIII-XIII [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 9 show a dynamic damper 10 as a first embodiment of the present invention. The dynamic damper 10 has a structure in which a mass member 12 is attached to a bracket 16 via two bushings 14, 14. In the following description, in principle, the vertical direction refers to the vertical direction in Figure 4, which is the axial direction of the bushings 14, the front-rear direction refers to the vertical direction in Figure 2, and the left-right direction refers to the left-right direction in Figure 2.

[0025] As shown in Figures 1 to 6, the mass member 12 is in the shape of a thick plate. To efficiently secure mass, the mass member 12 is made of a high-density material, such as iron or stainless steel. The mass member 12 is in the shape of a longitudinal plate, with the left-right direction being longer than the front-back direction. The mass member 12 has a symmetrical shape with respect to the left-right center in the left-right direction. As can be seen from Figures 2 and 3, the middle part of the mass member 12 in the left-right direction is a constricted portion 18 with a reduced front-back width dimension. The front and rear ends of the mass member 12 are convex portions 20, 20 with approximately the same front-back width dimension as the constricted portion 18. As shown in Figures 3 and 7, mounting holes 22 are formed between the constricted portion 18 and the convex portions 20, 20 of the mass member 12, penetrating in the vertical direction. These mounting holes 22, 22 extend parallel to each other and are arranged in the longitudinal direction (left-right direction) of the mass member 12. As a result, the mass member 12 has a cylindrical mounting section 24, 24 that extends vertically between the constricted section 18 and the protruding sections 20, 20. In addition, as shown in Figures 3, 7, and 8, a circular recessed cutout 26 that opens to the lower surface is formed in the constricted section 18 of the mass member 12.

[0026] A bushing 14 is attached to each of the mounting cylinder portions 24, 24 of the mass member 12. As shown in Figures 7 and 9, the bushing 14 has a structure in which a shaft member 28 and a sleeve member 30 are connected by a connecting rubber elastic body 32.

[0027] The shaft member 28 has a small diameter and is approximately cylindrical in shape, and is equipped with an internal hole 34 that penetrates it in the axial direction. The shaft member 28 is a rigid member, and is made of a metallic material such as iron or an aluminum alloy. The axial length dimension of the shaft member 28 is larger than the length dimension of the mounting hole 22 of the mass member 12. In the state in which the bush 14, described later, is mounted on the mass member 12, the axial direction of the shaft member 28 and the sleeve member 30 is vertical.

[0028] The sleeve member 30 has a generally cylindrical shape, thinner and larger in diameter than the shaft member 28, and integrally comprises a press-fit cylinder portion 36 extending in the vertical direction, a flange portion 38 protruding outward from the upper end of the press-fit cylinder portion 36, and an inner flange portion 40 protruding inward from the lower end of the press-fit cylinder portion 36. The sleeve member 30 is made of a rigid material, similar to the shaft member 28, and is formed of a metal material such as an aluminum alloy.

[0029] The sleeve member 30 is positioned radially away from the shaft member 28 in an externally fitted state, and the shaft member 28 and the sleeve member 30 are elastically connected to each other by a connecting rubber elastic body 32. The connecting rubber elastic body 32 integrally comprises a substantially cylindrical inner circumferential fixing portion 42 fixed to the shaft member 28, a substantially cylindrical outer circumferential fixing portion 44 fixed to the sleeve member 30, and an intermediate connecting portion 46 that connects the inner circumferential fixing portion 42 and the outer circumferential fixing portion 44 to each other.

[0030] The outer peripheral fixing portion 44 of the connecting rubber elastic body 32 is fixed to the inner circumferential surface of the sleeve member 30 and the upper surface of the inner flange portion 40. A first stopper rubber 48, integrally formed with the connecting rubber elastic body 32, is fixed to the upper surface of the flange portion 38 of the sleeve member 30. A second stopper rubber 50, which acts as a buffer rubber and is integrally formed with the connecting rubber elastic body 32, is fixed to the lower surface of the inner flange portion 40 of the sleeve member 30.

[0031] The intermediate connecting portion 46 of the connecting rubber elastic body 32 is substantially annular in shape and extends radially with a substantially constant thickness. Furthermore, as shown in Figure 7, a perforation hole 52 is formed in the intermediate connecting portion 46 that penetrates in the vertical direction. Preferably, multiple perforations 52 are provided, for example, by providing three evenly spaced holes in the circumferential direction, changes in the spring characteristics in the front-rear and left-right directions due to differences in orientation in the circumferential direction are suppressed when attaching the bush 14, which will be described later, to the mass member 12.

[0032] The bush 14 is attached to the mass member 12 by press-fitting the sleeve member 30 into the mounting hole 22 of the mass member 12. In this embodiment, a bush 14 is fitted into each of the two mounting holes 22, 22. As a result, shaft members 28 are inserted into each of the two mounting holes 22, 22 of the mass member 12, extending in the vertical direction, and these shaft members 28, 28 are elastically connected to the mass member 12 via the connecting rubber elastic bodies 32, 32 and the sleeve members 30, 30. The bush 14 is positioned appropriately in the axial direction relative to the mass member 12 by the flange portion 38 of the sleeve member 30 contacting the upper surface of the mounting cylinder portion 24. When the bush 14 is attached to the mass member 12, the shaft members 28 protrude outward both vertically and horizontally beyond the mounting cylinder portion 24. The intermediate connecting portion 46 of the connecting rubber elastic body 32 is positioned in the upper and lower central part of the mass member 12. Furthermore, the flange portion 38 and the inner flange portion 40 of the sleeve member 30 are positioned on the upper and lower periphery of the mounting hole 22 in the mass member 12, respectively, with the flange portion 38 extending outward from the mounting hole 22 and the inner flange portion 40 extending inward from the mounting hole 22.

[0033] Brackets 16 are attached to the shaft members 28, 28 of the two bushes 14, 14 mounted on the mass member 12. The brackets 16 are highly rigid members made of metal or the like, and as shown in Figures 10 and 11, they integrally include a shaft connecting portion 54 and a fixing portion 56.

[0034] The shaft connecting portion 54 of the bracket 16 is the part that connects the shaft members 28, 28 of the two bushes 14, 14 mounted on the mass member 12, and is plate-shaped, extending substantially perpendicular to the vertical direction. The shaft connecting portion 54 is longer in the left-right direction than in the front-back direction. In the left-right central part of the shaft connecting portion 54, a notched central cavity 58 is formed, which penetrates vertically and opens forward, and on both the left and right sides of the central cavity 58 are a pair of bush mounting portions 60, 60. The upper and lower surfaces of the bush mounting portion 60 are planes substantially perpendicular to the vertical direction. A screw hole 62 is formed in the bush mounting portion 60, which penetrates vertically. As shown in Figure 3, the bush mounting portion 60 is roughly disc-shaped when viewed from above, but its front end is a notch 64 that is cut out in a straight line extending to the left and right, so that the distance from the screw hole 62 to the front end (notch 64) is shorter than the distance from the screw hole 62 to the rear end and the left and right ends (see Figures 7 and 9). The notch 64 formed in the bush mounting portion 60 helps to reduce the weight of the bracket 16. The rear end portions of the pair of bush mounting portions 60, 60 are continuous with each other via reinforcing ribs 66 that protrude into the central cavity 58 and extend in the left and right directions, as shown in Figures 3, 10 and 11.

[0035] A cylindrical fastening portion 68 that protrudes downward is integrally formed on the opening periphery of the screw hole 62 of the shaft connecting portion 54, extending the screw hole 62 downward. This ensures a long axial length of the screw hole 62, providing sufficient threading allowance for the first bolt 76, described later, into the screw hole 62.

[0036] The shaft connecting portion 54 is provided projecting forward from the fixing portion 56. As shown in Figures 10 and 11, the fixing portion 56 is columnar in shape and extends linearly in the front-rear direction. In this embodiment, the fixing portion 56 is a substantially elongated cylindrical shape with the vertical direction as the long axis. Therefore, the fixing portion 56 has a flattened outer surface shape, and the outer diameter in the vertical direction is larger than the outer diameter in the left-right direction. The outer surface of the rear end of the fixing portion 56 is a tapered surface 70 that becomes smaller in diameter towards the rear. A projection portion 72 that projects upward is integrally formed at the front end of the fixing portion 56. Two bolt holes 74, 74 that penetrate in the axial direction are formed in the fixing portion 56. The bolt holes 74, 74 are provided parallel to each other and spaced apart in the vertical direction.

[0037] The fixing portion 56 is integral with the shaft connecting portion 54. Specifically, the reinforcing rib 66 of the shaft connecting portion 54 is integrally formed so as to protrude forward from the protruding portion 72 of the fixing portion 56, and a pair of bush mounting portions 60, 60 provided on both the left and right sides of the reinforcing rib 66 are integrally continuous with the fixing portion 56. In this way, the shaft connecting portion 54 is provided so as to protrude forward from the upper end of the fixing portion 56. As a result, the front openings of the bolt holes 74, 74 of the fixing portion 56 are exposed in the front view shown in Figure 4 without being covered by the shaft connecting portion 54.

[0038] In this embodiment, as can be seen from Figure 3, the bracket 16 does not cover the entire mass member 12 when projected from below. In particular, the outer peripheral edge of the mass member 12 is only covered by the left and right base end portions (connections with the fixing portions 56 of the bush mounting portions 60, 60) connected by the reinforcing ribs 66, and both ends of the mass member 12 in the front-rear and left-right directions protrude outward without being covered by the bracket 16. Furthermore, the constricted portion 18 located in the center of the longitudinal direction (left-right direction) of the mass member 12 is also separated from the bracket 16 in the front-rear direction by a central cavity 58 provided in the bracket 16, and is not covered by the bracket 16.

[0039] Furthermore, the shaft connecting portion 54 and the fixing portion 56 are integrally connected by rib-shaped connecting portions 75, 75. The rib-shaped connecting portions 75 are plate-shaped and extend vertically, are integrally formed with the shaft connecting portion 54, and protrude downward from the shaft connecting portion 54. The rib-shaped connecting portions 75 extend rearward from the left and right inner ends of the cylindrical fastening portion 68, and then bend inward to the left and right. Therefore, the rib-shaped connecting portions 75 are approximately L-shaped in the bottom view shown in Figure 3. The rib-shaped connecting portions 75 are provided on a pair of bush mounting portions 60, 60 of the shaft connecting portion 54, respectively. The rib-shaped connecting portions 75, 75 are integral with the front end of the fixing portion 56 and extend outward from the front end of the fixing portion 56 to the left and right. Thus, the rib-shaped connecting portions 75, 75 are integrally formed with both the shaft connecting portion 54 and the fixing portion 56, and connect the shaft connecting portion 54 and the fixing portion 56 to each other. Furthermore, because the shaft connecting portion 54 and the fixing portion 56 are also connected by the rib-shaped connecting portions 75, 75, the rigidity of the connection portion between the shaft connecting portion 54 and the fixing portion 56 is increased compared to the case where they are connected only at the reinforcing rib 66. In addition, the portion of the rib-shaped connecting portion 75 that extends outward to the left and right from the fixing portion 56 gradually increases in vertical dimension toward the fixing portion 56, and a large integrated continuous area with the fixing portion 56 is secured, thereby preventing damage due to stress concentration at the boundary between the fixing portion 56 and the rib-shaped connecting portion 75.

[0040] As shown in Figures 2 to 9, a mass member 12 is attached to the bracket 16 with the structure described above via two bushes 14, 14. Specifically, the lower surface of the shaft member 28 of the bush 14 is superimposed on the upper surface of the bush mounting portion 60 in the shaft connecting portion 54, and the first bolt 76 inserted through the shaft member 28 is screwed into the threaded hole 62 of the bush mounting portion 60, thereby attaching the shaft member 28 of the bush 14 to the bracket 16. In this embodiment, the shaft member 28 of the bush 14 is similarly attached to each of the two bush mounting portions 60, 60. Furthermore, since the mass member 12 is attached to the sleeve member 30 of the bush 14 as described above, the mass member 12 is attached to the bracket 16 via the bushes 14.

[0041] The mass member 12 is elastically supported by the bracket 16, thereby forming a mass-spring resonant system in which the mass member 12 acts as the mass and the connecting rubber elastic body 32 of the bush 14 acts as the spring. In this embodiment, the mass is adjusted by the protrusions 20, 20 provided at both the left and right ends of the mass member 12, thereby adjusting the vertical resonant frequency of the mass-spring resonant system. The resonant frequency of the mass-spring resonant system is not particularly limited, but is tuned to a relatively low frequency of, for example, about 30 Hz.

[0042] As shown in Figure 8, the reinforcing rib 66 connecting the two bush mounting portions 60, 60 is provided in the left-right central portion where the constricted portion 18 of the mass member 12 is located, and is therefore separated from the mass member 12 in the front-rear direction. As a result, even though the reinforcing rib 66, which is shaped like a curved plate and protrudes upward toward the center in the left-right direction, protrudes close to the lower surface of the mass member 12 in the vertical direction, interference with the mass member 12 due to vertical vibration input is avoided.

[0043] The inner flange portion 40 of the sleeve member 30 of the bush 14 and the bush mounting portion 60 of the bracket 16 face each other in the axial direction when the shaft member 28 is mounted on the bush mounting portion 60, and a second stopper rubber 50 is placed between the opposing surfaces of the inner flange portion 40 and the bush mounting portion 60. The contact between the inner flange portion 40 of the sleeve member 30 and the bush mounting portion 60 of the bracket 16 via the second stopper rubber 50 constitutes a rebound stopper that limits the relative upward displacement of the shaft member 28 with respect to the sleeve member 30 and the mass member 12.

[0044] As shown in Figure 9, the bush mounting portion 60 has a notch 64 formed in its front portion and is positioned on the inner circumference (rear) side relative to the inner flange portion 40 which is located on the lower opening periphery of the mounting hole 22 in the mass member 12. As a result, the rebound stopper formed by the contact between the inner flange portion 40 and the bush mounting portion 60 is configured in a roughly C-shaped annular region on the periphery of the mounting hole 22, excluding the front portion where the notch 64 is formed. The size of the notch 64 is set considering the load-bearing capacity and other factors required for the rebound stopper.

[0045] Furthermore, the stopper plate 78 is fastened together with the first bolt 76 that fastens the shaft member 28 and the bush mounting portion 60. The stopper plate 78 has a substantially annular plate shape, and as shown in Figure 2, the outer peripheral end is an annular shape that is continuous in the circumferential direction, and a plurality of through holes 80 arranged in the circumferential direction are formed in the radially intermediate portion. The stopper plate 78 is fixed to the shaft member 28 by the first bolt 76 while being superimposed on the upper surface of the shaft member 28. When the stopper plate 78 is attached to the shaft member 28, it protrudes further outward than the shaft member 28, and its outer peripheral end faces the flange portion 38 of the sleeve member 30 in the vertical direction. Then, a bound stopper is formed that limits the amount of downward relative displacement of the shaft member 28 with respect to the sleeve member 30 and the mass member 12 by the contact between the outer peripheral end of the stopper plate 78 and the flange portion 38 of the sleeve member 30 via the first stopper rubber 48.

[0046] In this embodiment, the dynamic damper 10 has a bracket 16 attached to the motor case 82, which is the object to be damped. More specifically, as shown in Figure 12, the fixing portion 56 of the bracket 16 is attached to the motor case 82 together with the motor mount 84, which is a vibration isolation device. The motor mount 84 is a cylindrical vibration isolation device having a structure in which an inner cylindrical member 86 and an outer cylindrical member 88, which are mounting members, are interconnected by a main rubber elastic body 90.

[0047] The inner cylinder member 86 is a rigid member made of metal or the like, and has a bottomed, approximately elongated cylindrical shape. The inner cylinder member 86 integrally comprises an elongated cylindrical peripheral wall 92 and a bottom wall 94 that closes the opening at the rear of the peripheral wall 92. The inner circumferential surface of the peripheral wall 92 of the inner cylinder member 86 is slightly larger in diameter than the outer circumferential surface of the fixing portion 56 of the bracket 16. Two through holes 96, 96 are formed through the bottom wall 94 of the inner cylinder member 86, corresponding to the two bolt holes 74, 74 formed in the fixing portion 56 of the bracket 16.

[0048] The outer cylinder member 88 is a roughly cylindrical shape with a thinner wall and larger diameter than the inner cylinder member 86, and is a hard member made of metal or the like, similar to the inner cylinder member 86. The outer cylinder member 88 is positioned externally on the outer circumference side of the peripheral wall 92 of the inner cylinder member 86, and the main rubber elastic body 90 is positioned radially between the outer cylinder member 88 and the peripheral wall 92 of the inner cylinder member 86.

[0049] The main rubber elastic body 90 is a thick-walled cylindrical shape, with its inner circumferential surface fixed to the circumferential wall 92 of the inner cylinder member 86, and its outer circumferential surface fixed to the inner circumferential surface of the outer cylinder member 88. The shape of the main rubber elastic body 90 is not particularly limited, but in this embodiment, the axial dimension of the outer circumferential end is smaller than that of the inner circumferential end, and both axial end faces extend in the circumferential direction with a curved cross-sectional shape that is recessed inward in the axial direction. The main rubber elastic body 90 may also have perforations such as those in the connecting rubber elastic body 32.

[0050] The motor mount 84 is attached to the motor case 82 by second bolts 98, 98, which act as fixing members and are inserted through through holes 96, 96, with the bottom wall 94 of the inner cylinder member 86 overlapping the motor case 82. The motor mount 84 is also attached to the vehicle body 100 by fixing the outer cylinder member 88 to the vehicle body 100 by means of press-fitting or other means. In this way, the motor mount 84 is interposed between the motor case 82 and the vehicle body 100. The motor case 82 is then vibration-damped and supported against the vehicle body 100 via the motor mount 84. When the motor mount 84 is mounted on the vehicle, a main vibration system is formed with the motor case 82 side as the mass and the main rubber elastic body 90 as the spring. In this main vibration system, the motor case 82 is excited and vibrates when the vehicle is running.

[0051] As shown in Figure 12, the fixing portion 56 of the bracket 16 is inserted into the inner cylindrical member 86 of the motor mount 84. The second bolts 98, 98, which are inserted through the bolt holes 74, 74 of the fixing portion 56 of the bracket 16, are then inserted through the insertion holes 96, 96 provided in the bottom wall 94 of the inner cylindrical member 86 and screwed into the threaded holes 62 of the motor case 82. As a result, the fixing portion 56 of the bracket 16 is fastened together with the inner cylindrical member 86 of the motor mount 84 to the motor case 82, and the dynamic damper 10 is attached to the motor case 82, which is the target of vibration damping. When the dynamic damper 10 is attached to the motor case 82, the shaft members 28, 28 of the bushes 14, 14 are fixed to the motor case 82 via the bracket 16, so the mass member 12 fixed to the sleeve members 30, 30 is elastically supported by the motor case 82 via the connecting rubber elastic bodies 32, 32.

[0052] Thus, the dynamic damper 10 is attached to the motor case 82 by indirectly fixing the fixing portion 56 of the bracket 16 to the motor case 82 via the inner cylindrical member 86 of the motor mount 84. Therefore, when attaching the dynamic damper 10 to the motor case 82, it is not necessary to process the motor case 82 to form a mounting surface for the fixing portion 56 of the bracket 16, and the dynamic damper 10 can be attached using the mounting surface of the motor mount 84. If the dynamic damper 10 is not needed, the fixing portion 56 of the bracket 16 does not need to be inserted into the inner cylindrical member 86 of the motor mount 84, and only the inner cylindrical member 86 needs to be fixed to the motor case 82.

[0053] In other words, in this embodiment, when the dynamic damper 10 is mounted on the motor case 82, which is the target of vibration damping, the bracket 16 of the dynamic damper 10 does not directly contact the motor case 82, but the bottom wall 94 of the inner cylinder member 86, which is the mounting member of the motor mount 84, contacts the motor case 82. Therefore, when additionally mounting the dynamic damper 10, there is no need to process and add a mounting surface on the motor case 82 that extends with high surface accuracy and strength. Furthermore, since the inner cylinder member 86 of the motor mount 84 is generally a metal press-formed product, sufficient surface accuracy can be obtained not only on the outer surface of the bottom wall that contacts the motor case 82, but also on the inner surface of the bottom wall that contacts the bracket 16, without requiring any special post-processing. In addition, the end face of the fixing portion 56 of the bracket 16 overlaps the inner surface of the bottom wall 94 of the inner cylinder member 86 over a sufficiently wide area (almost the entire surface), and is fastened to the mounting surface of the motor case 82 with the second bolts 98, 98. Therefore, by utilizing the bolt fixing force of the bracket 16, it is possible to improve the fixing strength of the bottom wall 94 of the inner cylinder member 86 to the motor case 82.

[0054] The fixing portion 56 of the bracket 16 protrudes forward of the peripheral wall 92 of the inner cylinder member 86 when inserted into the inner cylinder member 86. As a result, the fastening surface (front surface of the fixing portion 56) where the heads of the second bolts 98, 98 overlap is exposed in front of the peripheral wall 92 without being inserted into the peripheral wall 92. Therefore, when tightening the second bolts 98, 98, it is not necessary to insert a tool such as a wrench into the peripheral wall 92, and the second bolts 98, 98 can be easily tightened.

[0055] The fixing portion 56 of the bracket 16 has a tapered outer surface 70 at its rear end, which is the tip for insertion into the inner cylinder member 86, with the diameter decreasing towards the rear. This facilitates the insertion of the fixing portion 56 into the peripheral wall 92 of the inner cylinder member 86. Furthermore, although a curved radius (R) is set at the connection point between the peripheral wall 92 and the bottom wall 94 of the inner cylinder member 86, the tapered outer surface 70 at the rear end of the fixing portion 56 prevents interference between the fixing portion 56 and the curved radius of the inner cylinder member 86, even when the rear surface of the fixing portion 56 is in contact with the bottom wall 94 of the inner cylinder member 86.

[0056] For example, if the vertical direction in Figure 12 is the vertical up-and-down direction, and the fixing portion 56 of the bracket 16 is inserted into the inner cylinder member 86 without being fixed by the second bolts 98, 98, the dynamic damper 10 is likely to tilt so that the front is displaced downward by the weight of the mass member 12, which may cause the fixing portion 56 to come out of the inner cylinder member 86 and the dynamic damper 10 to fall off. Therefore, in this embodiment, as shown in Figures 12 and 13, the gap 102 between the fixing portion 56 and the peripheral wall 92 of the inner cylinder member 86 is made sufficiently small, so that when the dynamic damper 10 tilts, the fixing portion 56 and the peripheral wall 92 quickly engage to create a temporary holding state, preventing the fixing portion 56 from coming out forward of the inner cylinder member 86. With this temporary holding structure, the dynamic damper 10 is prevented from falling off the motor mount 84 even before the second bolts 98, 98 are tightened. Therefore, when fastening the fixing portion 56 of the bracket 16 and the inner cylinder member 86 to the motor case 82 with the second bolts 98, 98, it is not necessary to support the dynamic damper 10 while fastening the bolts, making it easier to attach the dynamic damper 10 to the motor case 82. The gap 102 between the fixing portion 56 of the bracket 16 and the peripheral wall 92 of the inner cylinder member 86 is set appropriately, for example, by considering the insertion length of the fixing portion 56 into the peripheral wall 92, the mass of the dynamic damper 10, the coefficient of friction between the fixing portion 56 and the inner cylinder member 86, etc.

[0057] The outer circumferential surface of the fixing portion 56 of the bracket 16 and the inner circumferential surface of the peripheral wall 92 of the inner cylinder member 86 are both shaped like elongated cylinders. Therefore, by making the gap 102 between the outer circumferential surface of the fixing portion 56 and the inner circumferential surface of the peripheral wall 92 sufficiently small, relative rotation between the fixing portion 56 and the peripheral wall 92 is restricted. As a result, the fixing portion 56 of the bracket 16 is positioned circumferentially with respect to the peripheral wall 92 of the inner cylinder member 86, and misalignment between the bolt holes 74, 74 of the fixing portion 56 and the insertion holes 96, 96 of the bottom wall 94 of the inner cylinder member 86 is suppressed.

[0058] In vehicles, the area around the motor case 82 is densely packed with other components such as auxiliary equipment and suspension, making it difficult to secure space for a dynamic damper. In particular, the mass member 12, which requires a certain size to ensure sufficient mass and displaces when vibration is input, requires a relatively large installation space, but sufficient space cannot always be secured around the motor case 82. Therefore, in this embodiment, the dynamic damper 10 has the mass member 12 provided in the front part, and the fixing part 56 that attaches to the motor case 82 is provided in the rear part, so that when the dynamic damper 10 is attached to the motor case 82, the mass member 12 is positioned away from the motor case 82. As a result, compared to the conventional structure in which the mass member 12 is arranged around the motor case 82, it is easier to secure space for the mass member 12, and it becomes easier to retrofit the dynamic damper 10, which is added according to the vehicle characteristics, to the vehicle. Furthermore, since the fixing portion 56 of the bracket 16, which is arranged around the motor case 82, is inserted into the inner cylindrical member 86 of the motor mount 84, space for its installation is secured in advance.

[0059] The dynamic damper 10, attached to the motor case 82, constitutes an additional secondary vibration system to the main vibration system that forms the vibration transmission path between the motor case 82 and the vehicle body 100. When a vibration to be damped in the vertical direction is input, the mass member 12 is displaced in a resonant state relative to the bracket 16, thereby reducing the vibration of the motor case 82. Consequently, the vibration transmitted from the motor case 82 to the vehicle body 100 is also reduced, improving the vibration state of the vehicle.

[0060] In this embodiment, a mass member 12, which is longitudinal in the left-right direction, is elastically supported by two bushes 14, 14 arranged in the left-right direction. Therefore, unintended displacements such as oscillation of the mass member 12 are suppressed in response to vibration input in the vertical direction, and the desired vibration damping effect can be stably obtained by the vertical translational motion of the mass member 12. Furthermore, compared to the case where the mass member 12 is supported by only one bush, the diameter of the bushes 14, 14 has been reduced, and the dynamic damper 10 has been made more compact, especially in the front-rear direction. In addition, since the mass member 12 has a symmetrical shape in the left-right direction, and the mass member 12 is supported by two substantially identical bushes 14, 14 arranged at the same distance from the center of the mass member 12, unintended displacements such as oscillation of the mass member 12 are prevented.

[0061] 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 number and arrangement of bushings connecting the mass member and the bracket are not particularly limited. However, when using multiple bushings, it is desirable that these bushings be arranged symmetrically with respect to the center of gravity of the mass member in order to achieve stable displacement of the mass member.

[0062] The shape of the mass member is preferably symmetrical with respect to the center of gravity in order to stabilize the displacement of the mass member, but it can be appropriately changed depending on the installation space and other factors.

[0063] The bolts used to secure the bracket's fixing portion and the vibration damping device's mounting member to the object to be damped may, for example, be designed to pass through the mounting member from the object to be damped and be screwed into the bracket's fixing portion or a nut provided on the fixing portion side. Note that the fixing member is not limited to bolts.

[0064] The fixing portion of the bracket is not limited to an elongated cylindrical shape as in the first embodiment, but may also be polygonal, irregularly shaped, or bottomed cylindrical, for example. Furthermore, while it is desirable for the fixing portion to have a flattened outer surface shape in order to restrict relative rotation with respect to the mounting member (inner cylindrical member) of the vibration damping device, it may also be a cylindrical surface, for example. Note that if the fixing portion has a polygonal or irregularly shaped shape, relative rotation with respect to the mounting member can be restricted even if the outer surface shape is not flattened.

[0065] Furthermore, the bracket's fixing portion does not necessarily need to be inserted into a bottomed cylindrical mounting member, as long as it is fixed to the vibration damping device together with the mounting member of the vibration isolation device. For example, it can be a plate-shaped piece that is superimposed on the axial end face of a columnar mounting member.

[0066] Furthermore, in the above embodiment, as shown in Figures 8 to 11, the shaft connecting portion 54 of the bracket 16 extended and spread out substantially parallel to the longitudinal direction of the fixing portion 56 (the central axis direction of the bolt hole 74). However, if, for example, the mounting surface of the motor mount 84 in the motor case 82 is inclined, it is also possible to incline the shaft connecting portion 54 relative to the longitudinal direction of the fixing portion 56 so that the shaft connecting portion 54 spreads out horizontally. In addition, if the mounting surface of the motor mount 84 in the motor case 82 is not a vertical plane but is inclined, this can be addressed by making the base end surface of the fixing portion 56 of the bracket 16 (the surface that overlaps the inner surface of the inner cylinder member 86 of the motor mount 84 with the inner wall 94) an inclined surface that is inclined by a predetermined angle from a plane perpendicular to the longitudinal direction of the fixing portion 56.

[0067] In the first embodiment, a dynamic damper 10 equipped with a bound stopper and a rebound stopper that limit the vertical displacement of the mass member 12 relative to the bracket 16 was illustrated. However, for example, stoppers that limit the displacement of the mass member 12 relative to the bracket 16 in the front-rear or left-right directions can also be provided.

[0068] The object to be damped is not limited to the motor case 82 as exemplified in the first embodiment, but may also be a power unit other than a motor, such as an engine. [Explanation of Symbols]

[0069] 10 Dynamic damper (first embodiment) 12 Mass members 14 Bush 16 brackets 18. Constricted area 20 Convex part 22 mounting holes 24 Mounting cylinder section 26. Weight reduction section 28 Shaft member 30 Sleeve component 32 Linked rubber elastic body 34 Internal bore 36 Press-fit cylinder section 38 Flange section 40 Inner flange section 42 Inner circumferential fixing portion 44 Outer peripheral fixing portion 46 Intermediate connecting section 48 First Stopper Rubber 50 Second stopper rubber (cushioning rubber) 52 slit holes 54 Shaft connection part 56 Fixed part 58 Central void 60 Bushing mounting section 62 screw holes 64 Notch 66 Reinforcement Ribs 68 Cylindrical fastening part 70 Tapered surface 72 Protrusion 74 bolt holes 75 Rib-shaped connecting section 76 First bolt 78 Stopper Plate 80 Through holes 82 Motor case (vibration damping target) 84. Motor mount (vibration isolation device, cylindrical vibration isolation device) 86 Inner cylinder member (mounting member) 88 Outer cylinder member 90 Main body rubber elastic material 92 Peripheral wall 94 Bottom wall 96 Through hole 98 Second bolt (fixing member, bolt) 100 Vehicle Body 102 Gap

Claims

1. The mass member is provided with a series of mounting holes that extend parallel to each other. A shaft member is inserted into each of these mounting holes. The mass member and a plurality of the shaft members are connected to each other by a connecting rubber elastic body. A dynamic damper in which the shaft member is attached to the object to be damped via a bracket, The mass member is elongated in the direction in which the plurality of mounting holes are aligned, and is symmetrical in the direction in which the plurality of mounting holes are aligned. The bracket is a dynamic damper comprising a fixing portion fixed to the vibration-damping target by a fixing member common to the mounting member for the vibration-damping target in a vibration-damping device that supports the vibration-damping target, and an axial connecting portion that protrudes from the fixing portion in a direction intersecting the direction of alignment of the plurality of mounting holes and connects the plurality of axial members to each other.

2. The vibration isolation device is a cylindrical vibration isolation device in which an inner cylindrical member and an outer cylindrical member, which are bottomed cylindrical mounting members, are connected by a main body rubber elastic material. The dynamic damper according to claim 1, wherein the fixing portion of the bracket inserted into the inner cylindrical member is fastened together with the bottom wall of the inner cylindrical member with a bolt that serves as the fixing member and fixed to the vibration damping target.

3. The dynamic damper according to claim 2, wherein the fixing portion of the bracket inserted into the inner cylindrical member of the vibration damping device protrudes from the peripheral wall of the inner cylindrical member on the side opposite to the bottom wall of the inner cylindrical member.

4. The aforementioned fixing portion has a flat outer surface shape, The dynamic damper according to any one of claims 1 to 3, wherein the shaft connecting portion extends from the outer peripheral end on the long side of the fixed portion.

5. The shaft connecting portion is made into a plate shape that extends in a direction perpendicular to the shaft member, An axial stopper is configured to limit the amount of relative displacement of the shaft member in the axial direction with respect to the mass member by contact between the opening periphery of the mounting hole in the mass member and the shaft connecting portion via a buffer rubber. The dynamic damper according to any one of claims 1 to 3, wherein the tip of the shaft connecting portion that protrudes from the fixing portion is located on the inner circumference side of the opening periphery of the mounting hole.

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