Dynamic damper

Abstract

This invention provides a novel dynamic damper structure that ensures vibration damping performance with a compact design, thereby improving durability and enhancing the vibration-damping support performance of suspension members. [Solution] A dynamic damper 10 is mounted on a cylindrical member mount 12 in which an inner shaft member 42 and an outer cylindrical member 44 are connected by an elastic body 46. The dynamic damper 10 includes a mounting bracket 14 which is disposed on one axial end of the inner shaft member 42 and fixed to the inner shaft member 42 such that a cylindrical peripheral wall portion 20 extends in the direction of the central axis, an annular mass body 16 which is disposed spaced apart on the outer circumference of the peripheral wall portion 20, and a connecting rubber elastic body 18 which connects the peripheral wall portion 20 and the mass body 16 in a direction perpendicular to the axis. The connecting rubber elastic body 18 has covering rubber portions 38a and 38b integrally formed thereon which hold the inner circumference of the mass body 16 so as to cover it from both axial sides, and the axial dimension of the connecting rubber elastic body 18 is smaller than the axial dimension of the peripheral wall portion 20.

Description

Technical Field

[0001] The present invention relates to a dynamic damper mounted on a member mount that vibrationally supports a suspension member of a vehicle.

Background Art

[0002] Conventionally, member mounts equipped with dynamic dampers have been studied for the purpose of improving the vibration isolation support performance of suspension members. For example, the adoption of a dynamic damper such as Japanese Unexamined Patent Application Publication No. 2023-054685 (Patent Document 1) can be considered.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the dynamic damper with a conventional structure such as Patent Document 1 is relatively large, and there is still room for improvement in recent vehicles where the mounting space is limited in order to achieve miniaturization while ensuring vibration damping performance.

[0005] Further, in such a conventional dynamic damper, in order to secure the press-fitting area of the mass body to the press-fitting sleeve (cylindrical portion), the mass body becomes long vertically, and it becomes difficult to stably support the mass body by the elastic connecting body located at the lower end. Therefore, it is difficult to ensure the durability of the elastic connecting body, and there are also problems such as it being difficult to avoid an adverse effect on the vibration isolation performance due to large swinging of the mass body.

[0006] The problem to be solved by the present invention is to provide a dynamic damper with a novel structure that can ensure vibration damping performance with a compact structure and realize improvements in durability and vibration isolation support performance of a suspension 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 mounted on a cylindrical member mount in which an inner shaft member and an outer cylindrical member are connected by an elastic body, and comprises a mounting bracket having a cylindrical peripheral wall portion, disposed on one axial end side of the inner shaft member of the member mount and fixed to the inner shaft member such that the peripheral wall portion extends in the direction of the central axis, an annular mass body disposed spaced apart on the outer circumference side of the peripheral wall portion of the mounting bracket, and a connecting rubber elastic body connecting the peripheral wall portion and the mass body between opposing surfaces perpendicular to the axis, wherein the connecting rubber elastic body has a covering rubber portion integrally formed on its outer circumference that extends to the end faces on both axial sides of the mass body and holds the inner circumference portion of the mass body from both axial sides, and the axial dimension of the connecting rubber elastic body is smaller than the axial dimension of the peripheral wall portion.

[0009] In a dynamic damper with a structure according to this embodiment, the mass body is directly fixed to the connecting rubber elastic body, eliminating the need for press-fit sleeves and press-fitting processes in conventional structures, thus simplifying the structure and making it more compact.

[0010] Furthermore, a covering rubber portion is provided to cover the inner circumference of the mass body from both axial sides, and the inner circumference of the mass body is embedded so as to fit into the integrally formed connecting rubber elastic body and covering rubber portion. This ensures a stable fixing area and fixing strength for the mass body to the connecting rubber elastic body and covering rubber portion. Moreover, the center of gravity of the mass body and the elastic center of the connecting rubber elastic body can be brought closer together in the axial direction, achieving stable support for the mass body. This stabilizes the displacement of the mass body during vibration input, thereby improving vibration isolation performance.

[0011] Furthermore, since the portion where the mass is fixed to the connecting rubber elastic body is provided with covering rubber portions on both axial sides, even if the position of the mass is slightly shifted in the axial direction during the molding of the connecting rubber elastic body, the fixing area of ​​the connecting rubber elastic body and the covering rubber portion to the mass is stably secured, thereby stably obtaining the desired performance.

[0012] Furthermore, since the axial dimension of the connecting rubber elastic body is smaller than the axial dimension of the peripheral wall, space can be efficiently secured in the outer peripheral region of the peripheral wall to allow for elastic deformation of the connecting rubber elastic body and displacement of the mass, making it easier to avoid interference with other members arranged around the dynamic damper.

[0013] The second embodiment is a dynamic damper described in the first embodiment, wherein the axial end faces of the connecting rubber elastic body between the circumferential wall portion and the mass body in the direction perpendicular to the axis are located axially outward from the axial end faces of the inner circumferential portion of the mass body, and the covering rubber portion is integrally formed by the axial side portions of the connecting rubber elastic body extending outward.

[0014] A dynamic damper with a structure according to this embodiment can effectively achieve the following: securing the contact area and fixing strength of the mass body to the connecting rubber elastic body by the covering rubber portion, improving vibration isolation performance by stabilizing the displacement of the mass body during vibration input, and avoiding interference with other components by securing space. Furthermore, it becomes possible to efficiently secure the elastic properties of the connecting rubber elastic body, including the covering rubber layer, in a limited narrow space, and it also becomes possible to improve the durability of the connecting rubber elastic body, including the covering rubber portion.

[0015] A third embodiment is a dynamic damper described in the first or second embodiment, wherein the inner circumference of the mass body is provided with a thickened portion whose axial dimension is larger than that of the outer circumference.

[0016] In a dynamic damper structured according to this embodiment, the mass of the mass body is distributed more in the inner circumference side, which is closer to the support position by the connecting rubber elastic body, than in the outer circumference side. This stabilizes the displacement of the mass body during vibration input, thereby improving vibration isolation performance.

[0017] The fourth aspect is the dynamic damper described in the third aspect, wherein, on the axial end face of the mass body, the covering rubber portion extends beyond the thickened portion to the outer circumference and covers the outer circumference of the thickened portion.

[0018] In a dynamic damper with a structure according to this embodiment, the thickened portion of the mass body, which has an increased mass, is covered and supported by a connecting rubber elastic body and a covering rubber portion that extends to the outer circumference. As a result, the displacement of the mass body during vibration input becomes more stable, and vibration isolation performance is further improved.

[0019] The fifth embodiment is a dynamic damper described in any one of the first to fourth embodiments, wherein the mounting bracket and the mass body are vulcanized and bonded to the connecting rubber elastic body.

[0020] According to the dynamic damper structured according to this aspect, by vulcanizing and bonding the mounting metal fitting and the mass body during the vulcanization molding of the connecting rubber elastic body, the bonding process can be omitted, and high bonding strength can be easily obtained.

[0021] The sixth aspect is the dynamic damper described in any one of the first to fifth aspects, in which the material casting mark during molding in the connecting rubber elastic body is at the outer peripheral end portion of the covering rubber portion.

[0022] According to the dynamic damper structured according to this aspect, it is difficult for the material casting mark to affect the characteristics of the connecting rubber elastic body provided on the inner peripheral side of the covering rubber portion, and the performance of the connecting rubber elastic body that is likely to affect the mass-spring system is stabilized. Therefore, the vibration damping performance can be efficiently exhibited when vibration is input.

[0023] The seventh aspect is the dynamic damper described in any one of the first to sixth aspects, in which the mounting metal fitting is provided with a flange-shaped portion that extends from the axial end portion located on the opposite side of the member mount in the axial direction on the peripheral wall portion to the outer peripheral side, and the outer peripheral end of the flange-shaped protrusion is located on the outer peripheral side of the inner peripheral end of the mass body, constituting a fail-safe mechanism for preventing the mass body from detaching due to the breakage of the connecting rubber elastic body.

[0024] According to the dynamic damper structured according to this aspect, even if the connecting rubber elastic body breaks, the mass body can be prevented from detaching and falling onto the road surface by being caught by the flange-shaped portion of the mounting metal fitting.

[0025] The eighth aspect is the dynamic damper described in any one of the first to seventh aspects, in which the peripheral wall portion is a tapered portion whose axial end portion side located on the member mount side gradually decreases in diameter toward the axially outer side, and the connecting rubber elastic body is also fixed to the outer peripheral surface of the tapered portion.

[0026] According to the dynamic damper structured according to this aspect, since the peripheral wall portion of the mounting fitting has a small diameter in the tapered portion, interference with other surrounding members is likely to be avoided. Further, since the connecting rubber elastic body is also fixed to the outer peripheral surface of the tapered portion, it becomes easier to secure a larger fixing area of the connecting rubber elastic body to the mounting fitting.

[0027] A ninth aspect is the dynamic damper described in any one of the first to eighth aspects, wherein the mounting fitting is provided with a flat bottom wall portion that extends inward in the axial direction from an axial end portion located on the member mount side in the peripheral wall portion, and an annular step portion is provided on an outer peripheral portion of the bottom wall portion, and an attachment surface protruding axially is provided on the inner peripheral side of the step portion

[0028] According to the dynamic damper structured according to this aspect, the fixing range of the connecting rubber elastic body to the bottom wall portion of the mounting fitting is defined by a step portion provided on the bottom wall portion of the mounting fitting, and it is possible to prevent the burrs of the connecting rubber elastic body from extending to the attachment surface on the inner peripheral side of the step portion.

[0029] A tenth aspect is the dynamic damper described in the ninth aspect, wherein a brace fitting that extends in a direction perpendicular to the axis is provided at one axial end portion of the inner shaft member in the member mount, and an annular rising piece portion that is located on the outer peripheral side of the covering rubber portion of the connecting rubber elastic body and extends axially toward the mass body is formed at an outer peripheral edge portion of the brace fitting, and an annular concave step portion is provided at a radially intermediate portion on an outer axial surface of the brace fitting, and a surface to be attached that is recessed axially is provided on the inner peripheral side of the concave step portion, and the attachment surface of the mounting fitting is overlapped with the surface to be attached, and the step portion of the mounting fitting is aligned in a direction perpendicular to the axis with respect to the concave step portion.

[0030] According to the dynamic damper structure in this embodiment, the mounting bracket and the brace bracket can be aligned perpendicular to the axis by the stepped portion and the concave stepped portion. Since the extension of the connecting rubber elastic body relative to the mounting surface of the mounting bracket is prevented by the stepped portion, rubber is prevented from being interposed between the overlapping surfaces of the mounting surface of the mounting bracket and the non-mounting surface of the brace bracket, thereby firmly fixing the mounting bracket and the brace bracket. [Effects of the Invention]

[0031] According to the present invention, a dynamic damper mounted on a member mount can achieve vibration damping performance with a compact structure, thereby improving durability and vibration-damping support performance of the suspension member. [Brief explanation of the drawing]

[0032] [Figure 1] A vertical cross-sectional view showing a dynamic damper as the first embodiment of the present invention mounted on a member mount. [Figure 2] Plan view of the mounting bracket constituting the dynamic damper shown in Figure 1. [Figure 3] Bottom view of the mounting bracket shown in Figure 2. [Figure 4] Plan view of the mass member constituting the dynamic damper shown in Figure 1. [Figure 5] Bottom view of the mass member shown in Figure 4. [Modes for carrying out the invention]

[0033] Embodiments of the present invention will be described below with reference to the drawings.

[0034] Figure 1 shows a dynamic damper 10 as a first embodiment of the present invention, mounted on a member mount 12. The dynamic damper 10 has a structure in which a mounting bracket 14 and a mass member 16 as a mass body are connected by a connecting rubber elastic body 18. In the following description, the vertical direction generally refers to the vertical direction in Figure 1, which is the axial direction.

[0035] As shown in Figures 1 to 3, the mounting bracket 14 is a bottomed cylindrical shape with an inverted orientation overall, and is made of a metal such as iron or aluminum alloy. The mounting bracket 14 has a structure in which the bottom wall portion 22 protrudes inward from the upper end of the approximately cylindrical peripheral wall portion 20.

[0036] The upper end of the peripheral wall portion 20 of the mounting bracket 14 is a tapered portion 24 that gradually decreases in diameter towards the top. The angle of inclination of the tapered portion 24 may change in the vertical direction, but in this embodiment, it decreases in diameter towards the top at a substantially constant angle of inclination. In addition, a flange-like projection 26 that widens towards the outer circumference is provided at the lower end of the peripheral wall portion 20 of the mounting bracket 14. In this embodiment, the flange-like projection 26 is formed by bending the lower end of the peripheral wall portion 20 toward the outer circumference, so the lower end of the peripheral wall portion 20 widens downward. The intermediate portion of the peripheral wall portion 20 in the vertical direction is a straight cylindrical shape that extends substantially parallel to the vertical direction.

[0037] The bottom wall portion 22 of the mounting bracket 14 is a roughly annular plate shape that widens substantially perpendicular to the vertical direction, and a bolt insertion hole 28 that penetrates vertically is provided in the central portion. The bottom wall portion 22 has an annular stepped portion 30 on its outer circumference, and the mounting surface 32 is formed on the inner circumference side of the stepped portion 30 that protrudes upward more than the outer circumference side. The mounting surface 32 has a flat surface on its upper and lower surfaces that widens perpendicular to the vertical direction.

[0038] As shown in Figures 1, 4, and 5, the mass member 16 has a generally circular shape and extends continuously in an annular manner with a substantially constant cross-sectional shape. It is desirable that the mass member 16 be made of a high-density metal material such as iron. The inner diameter of the mass member 16 is larger than the outer diameter of the upper and lower intermediate portion of the peripheral wall portion 20 of the mounting bracket 14. Furthermore, it is desirable that the inner diameter of the mass member 16 be smaller than the outer diameter of the flange-shaped projection 26 of the mounting bracket 14, and that the outer peripheral end of the flange-shaped projection 26 is located on the outer peripheral side of the inner peripheral end of the mass member 16 to constitute a fail-safe mechanism described later.

[0039] The inner circumference of the mass member 16 is provided with a thickened portion 34, which has a greater vertical dimension (thickness dimension) than the outer circumference. The lower surface of the thickened portion 34 is a common plane with the outer circumference, and the upper surface protrudes upward from the upper surface of the outer circumference. In short, the thickened portion 34 is made thick so as to protrude upward from the outer circumference. The radial width dimension of the thickened portion 34 is set to avoid interference with the rising piece 64 of the brace fitting 56, which will be described later, and in this embodiment, it is set to be less than half of the radial width dimension of the entire mass member 16. Furthermore, the upward protrusion height dimension of the thickened portion 34 is set to avoid interference with the brace fitting 56, which will be described later, and in this embodiment, it is set to be less than half of the thickness dimension of the outer circumference of the mass member 16.

[0040] The mass member 16 is externally fitted to the peripheral wall portion 20 of the mounting bracket 14, spaced apart on the outer circumference side, and the peripheral wall portion 20 of the mounting bracket 14 and the mass member 16 are elastically connected to each other by a connecting rubber elastic body 18. The connecting rubber elastic body 18 is annular in shape as a whole and is provided between the peripheral wall portion 20 of the mounting bracket 14 and the mass member 16 in the radial direction. The mounting bracket 14 and the mass member 16 may be fixed to the connecting rubber elastic body 18 after molding by means of adhesive or welding, but in this embodiment they are vulcanized and bonded to the connecting rubber elastic body 18 during molding. Therefore, the connecting rubber elastic body 18 in this embodiment is formed as an integrally vulcanized molded product comprising the mounting bracket 14 and the mass member 16. That is, the inner circumferential surface of the connecting rubber elastic body 18 is vulcanized and bonded to the peripheral wall portion 20 of the mounting bracket 14, and the outer circumferential surface is vulcanized and bonded to the mass member 16.

[0041] The upper end of the connecting rubber elastic body 18 reaches the tapered portion 24 of the peripheral wall portion 20 of the mounting bracket 14, and is also vulcanized and bonded to the outer surface of the tapered portion 24. The upper part of the tapered portion 24 that constitutes the upper end of the peripheral wall portion 20 of the mounting bracket 14 and the flange-shaped projection 26 that constitutes the lower end both protrude outward in the vertical direction from the connecting rubber elastic body 18, so that the vertical dimension of the connecting rubber elastic body 18 is smaller than the vertical dimension of the peripheral wall portion 20. The upper surface of the flange-shaped projection 26 of the mounting bracket 14 is covered with a buffer rubber layer 36 that is integrally formed with the connecting rubber elastic body 18.

[0042] The connecting rubber elastic body 18, positioned radially between the peripheral wall portion 20 of the mounting bracket 14 and the mass member 16, has both of its upper and lower end faces positioned axially outward from both of the upper and lower end faces of the thickened portion 34 of the mass member 16, and its vertical dimension is larger than that of the thickened portion 34. Furthermore, the connecting rubber elastic body 18 has covering rubber portions 38a and 38b integrally formed by the upper and lower end portions extending outward. In this embodiment, the connecting rubber elastic body 18 is radially continuous between the outer circumferential surface of the peripheral wall portion 20 of the mounting bracket 14 and the inner circumferential surface (including the axially extended portion) of the mass member 16.

[0043] The covering rubber portion 38a extends outward from the upper end of the outer peripheral end of the connecting rubber elastic body 18 and spreads to the upper end surface of the thickened portion 34 of the mass member 16, covering the upper surface of the thickened portion 34. The covering rubber portion 38a extends to the outer peripheral side of the thickened portion 34 of the mass member 16 and covers the outer peripheral surface of the thickened portion 34. The outer diameter of the covering rubber portion 38a is smaller than the inner diameter of the rising piece portion 64 of the brace fitting 56, which will be described later. The covering rubber portion 38b extends outward from the lower end of the outer peripheral end of the connecting rubber elastic body 18 and spreads to the lower end surface of the thickened portion 34 of the mass member 16, covering the lower end surface of the thickened portion 34. The covering rubber portion 38b is separated upward from the buffer rubber layer 36 that covers the upper surface of the flange-shaped projection 26.

[0044] Because the covering rubber portions 38a and 38b are integrally formed with the connecting rubber elastic body 18, the thickened portion 34, which is the inner circumference of the mass member 16, is vulcanized and bonded to the connecting rubber elastic body 18 and the covering rubber portions 38a and 38b over a wide area, so as to fit into the connecting rubber elastic body 18 and the covering rubber portions 38a and 38b. The outer circumference of the mass member 16 protrudes further outward than the covering rubber portions 38a and 38b. In this embodiment, the covering rubber portion 38a that covers the upper side of the mass member 16 extends further outward than the covering rubber portion 38b that covers the lower side of the mass member 16. A material casting mark 40 is formed on the covering rubber portion 38a that protrudes further outward. The material casting mark 40 is the trace of a gate for injecting rubber material into the mold cavity when molding the connecting rubber elastic body 18, and is located at the outer circumference end of the covering rubber portion 38a. In this embodiment, the material casting marks 40 protrude at the corner where the upper surface and the outer peripheral surface of the covering rubber portion 38a intersect.

[0045] Furthermore, the connecting rubber elastic body 18 is not fixed to the mounting surface 32 of the bottom wall portion 22 of the mounting bracket 14. That is, when the connecting rubber elastic body 18 is molded, the mounting bracket 14 set in the mold utilizes the stepped portion 30 provided on the outer circumference side of the mounting surface 32 of the bottom wall portion 22 to define the formation position of the connecting rubber elastic body 18, including burrs during molding, and prevents rubber material from penetrating onto the mounting surface 32 on the inner circumference side of the stepped portion 30. Therefore, both the upper and lower surfaces of the mounting surface 32 are exposed and not covered with rubber.

[0046] In the dynamic damper 10, since the mass member 16 is directly fixed to the connecting rubber elastic body 18, a press-fit sleeve for attaching the mass member 16 is unnecessary, and the press-fit process can also be omitted. As a result, the dynamic damper 10 can be simplified and made more compact by reducing the number of parts.

[0047] In this embodiment, the connecting rubber elastic body 18 is vulcanized and bonded to the mounting bracket 14 and the mass member 16, and the connecting rubber elastic body 18 is formed as an integrally vulcanized molded product equipped with the mounting bracket 14 and the mass member 16. Therefore, there is no need to bond the mounting bracket 14 and the mass member 16 in a separate process after the molding of the connecting rubber elastic body 18, thus simplifying manufacturing. Furthermore, high adhesive strength can be obtained by vulcanizing and bonding the mounting bracket 14 and the mass member 16 to the connecting rubber elastic body 18. Note that the connecting rubber elastic body 18, the buffer rubber layer 36, and the covering rubber parts 38a and 38b are integrally vulcanized and molded.

[0048] Since the inner circumference of the mass member 16 is a thick-walled portion 34 with a large axial dimension, it is easy to obtain a large bonding area between the inner circumference of the mass member 16 and the connecting rubber elastic body 18. Furthermore, the thick-walled portion 34, which is the inner circumference of the mass member 16, is covered from both sides in the axial direction by the covering rubber portions 38a and 38b, and is embedded so as to fit between the covering rubber portions 38a and 38b. Therefore, a large bonding area between the mass member 16 and the connecting rubber elastic body 18 can be secured, and a stable and large bonding strength can be secured.

[0049] Even if the position of the mass member 16 is slightly shifted in the axial direction during the molding of the connecting rubber elastic body 18, the covering rubber portions 38a and 38b are provided on both sides of the mass member 16 in the axial direction. This ensures a stable contact area between the connecting rubber elastic body 18 and the covering rubber portions 38a and 38b and the mass member 16, thereby stably obtaining the desired performance, such as bonding strength.

[0050] The connecting rubber elastic body 18, which is fixed to the peripheral wall portion 20 of the mounting bracket 14, is fixed up to the outer surface of the tapered portion 24 in the peripheral wall portion 20. This allows for a larger fixing area of ​​the connecting rubber elastic body 18 to the mounting bracket 14, and enables a more stable and greater fixing strength.

[0051] The dynamic damper 10, having the structure described above, is attached to the member mount 12, as shown in Figure 1. The member mount 12 is a cylindrical vibration isolation device, having a structure in which an inner shaft member 42 and an outer cylindrical member 44 are connected by an elastic body 46.

[0052] The inner shaft member 42 has a thick-walled, small-diameter cylindrical shape and extends straight in the vertical direction. The central hole of the inner shaft member 42 is larger in diameter than the bolt insertion hole 28 formed in the mounting bracket 14 of the dynamic damper 10. It is desirable that the outer diameter of the lower end surface of the inner shaft member 42 is less than or equal to the outer diameter of the mounting surface 32 on the bottom wall portion 22 of the mounting bracket 14.

[0053] The outer cylindrical member 44 has a thin-walled, large-diameter, substantially cylindrical shape, and an annular plate-shaped flange portion 48 is integrally formed at its lower end, projecting outward. The minimum inner diameter of the outer cylindrical member 44 is larger than the outer diameter of the inner shaft member 42. The upper end of the outer cylindrical member 44 is a reduced-diameter portion 50 that becomes smaller towards the top.

[0054] With the inner shaft member 42 inserted through the outer cylindrical member 44, an elastic body 46 is provided radially between the inner shaft member 42 and the outer cylindrical member 44. The elastic body 46 is substantially cylindrical in shape overall, with its inner circumferential surface vulcanized and bonded to the outer circumferential surface of the inner shaft member 42, and its outer circumferential surface vulcanized and bonded to the inner circumferential surface of the outer cylindrical member 44. The elastic body 46 may have a constant cross-sectional shape around its entire circumference, but in this embodiment, perforations 52 are provided on both sides in one radial direction on either side of the inner shaft member 42, thereby adjusting the spring ratio in two directions perpendicular to the axis. A stopper rubber 54, integrally formed with the elastic body 46, is provided protruding downward from the lower surface of the flange portion 48 of the outer cylindrical member 44. Furthermore, by reducing the diameter of the outer cylindrical member 44 after the vulcanization molding of the elastic body 46, the tensile stress caused by thermal shrinkage of the elastic body 46 after molding can be alleviated, thereby improving the durability of the elastic body 46. Furthermore, when the outer cylindrical member 44 is processed to reduce its diameter, the upper end of the outer cylindrical member 44 is reduced in diameter even more to form a reduced-diameter portion 50. This pre-compresses the upper end of the elastic body 46 in the radial direction, thereby further improving the durability of the elastic body 46.

[0055] A brace fitting 56, which extends approximately perpendicular to the vertical direction, is superimposed on the lower surface of the inner shaft member 42. The brace fitting 56 has a generally circular plate shape, and a bolt insertion hole 58 is formed in the central part in the radial direction. The brace fitting 56 is a highly rigid member made of metal. The brace fitting 56 has a stepped portion 60 in the middle of the radial direction, and the inner circumference side of the stepped portion 60 is located above the outer circumference side. As a result, the inner circumference side of the brace fitting 56 is recessed upward from the stepped portion 60, and the lower surface of this recessed portion is the mounting surface 62.

[0056] A cylindrical rising piece 64 projecting downward is integrally formed on the outer peripheral end of the brace fitting 56. The provision of the rising piece 64 increases the deformation rigidity of the annular plate-shaped brace fitting 56. The radial distance between the stepped portion 60 and the rising piece 64 of the brace fitting 56 is a stopper contact portion 66 that faces the flange portion 48 of the outer cylindrical member 44 in the vertical direction, and it widens substantially perpendicular to the vertical direction.

[0057] The dynamic damper 10 is attached to the member mount 12 which has this structure. Specifically, the mounting surface 32 of the bottom wall portion 22 of the mounting bracket 14 is superimposed from below on the mounting surface 62 of the brace bracket 56, and the peripheral wall portion 20 of the mounting bracket 14 is positioned below the inner shaft member 42 with the peripheral wall portion 20 extending in the direction of the central axis of the inner shaft member 42. The inner shaft member 42, the brace bracket 56, and the mounting bracket 14 are then fixed to each other by bolts 68 inserted through the bolt insertion holes 28 of the mounting bracket 14, the bolt insertion holes 58 of the brace bracket 56, and the central hole of the inner shaft member 42. In this way, the dynamic damper 10 is attached to the inner shaft member 42 of the member mount 12 by the mounting bracket 14. In this embodiment, a spacer 70 is interposed between the head of the bolt 68 and the bottom wall portion 22 of the mounting bracket 14.

[0058] When the brace fitting 56 is attached to the inner shaft member 42, it protrudes further outward than the inner shaft member 42, and the stopper contact portion 66 of the brace fitting 56 faces downward relative to the flange portion 48 of the outer cylindrical member 44. The stopper rubber 54 protruding from the flange portion 48 of the outer cylindrical member 44 is in contact with the stopper contact portion 66 of the brace fitting 56 in advance, and the stopper rubber 54 is compressed vertically between the flange portion 48 and the stopper contact portion 66. The brace fitting 56 may be fixed to the inner shaft member 42 by means of welding or other means, for example, after the vulcanization molding of the elastic body 46, with the upper surface of the recessed portion on the inner circumference side of the stepped portion 60 overlapping the lower end surface of the inner shaft member 42.

[0059] The bottom wall portion 22 of the mounting bracket 14 has a smaller diameter than the stepped portion 60 of the brace bracket 56 and is inserted into the inner circumference of the stepped portion 60. Therefore, the stepped portion 30 of the bottom wall portion 22 and the stepped portion 60 of the brace bracket 56 align the mounting bracket 14 to some extent in the radial direction with respect to the brace bracket 56, thereby facilitating the positioning work of the mounting bracket 14 before fixing it to the brace bracket 56 and the inner shaft member 42. In this embodiment, the entire lower surface on the inner circumference side of the stepped portion 60 of the brace bracket 56 is used as the mounting surface 62. However, for example, a concave stepped portion can be provided on the inner circumference side of the stepped portion 60 of the brace bracket 56, and the inner circumference side of the concave stepped portion can be recessed upwards so that it is positioned above the outer circumference side, thereby making the lower surface of the recessed portion the mounting surface. In this case, for example, it is desirable to set the inner diameter of the concave step portion of the brace fitting 56 to be the same as or slightly larger than the outer diameter of the step portion 30 provided on the bottom wall portion 22 of the mounting fitting 14 of the dynamic damper 10. This makes it possible to align the mounting fitting 14 and the brace fitting 56 with even greater radial precision before fixing them in place by inserting the step portion 30 of the mounting fitting 14 into the concave step portion of the brace fitting 56 and overlapping the mounting surface 32 of the mounting fitting 14 with the mounting surface of the brace fitting 56.

[0060] The rising portion 64 of the brace fitting 56 is located on the outer circumference side of the covering rubber portion 38a and protrudes downward toward the outer circumference of the mass member 16. The rising portion 64 is separated upward from the outer circumference of the mass member 16, which is thinner than the inner circumference, allowing for vertical displacement of the mass member 16.

[0061] In the state in which the dynamic damper 10 is mounted on the member mount 12, the rising piece 64 of the brace fitting 56 is located on the outer circumference side of the thickened portion 34 of the mass member 16. The rising piece 64 is located on the outer circumference side of the covering rubber portion 38a that covers the outer circumference surface of the thickened portion 34 of the mass member 16. The protruding tip surface (lower end surface) of the rising piece 64 is spaced upward relative to the upper surface of the outer circumference portion of the mass member 16. The mass member 16 has a larger mass while avoiding interference with the rising piece 64 because the inner circumference portion is thicker than the outer circumference portion. The rising piece 64 protrudes to a position where it overlaps with the covering rubber portion 38a that covers the upper surface of the thickened portion 34 of the mass member 16 in radial projection. In this arrangement, the outer peripheral portion of the brace fitting 56 forms a cover portion that covers the upper part of the thickened portion 34 that protrudes upward on the inner circumference of the mass member 16, and the covering rubber portion 38a that covers the upper part of the thickened portion 34, at a distance from above and the outer circumference. As a result, the upper part of the thickened portion 34 and the covering rubber portion 38a are protected from impacts by foreign objects from above and the outer circumference, as well as from heat radiation, effectively preventing deterioration and damage to the covering rubber portion 38a and, consequently, to the connecting rubber elastic body 18.

[0062] The member mount 12 is attached to the vehicle by, for example, the inner shaft member 42 being attached to the vehicle body side (not shown) by bolts 68, and the outer cylindrical member 44 being press-fitted and fixed into the mounting hole 74 of the suspension member 72.

[0063] When vertical vibrations are applied between the inner shaft member 42 and the outer cylindrical member 44 while the member mount 12 is installed in the vehicle, the vibration damping effect is exerted due to the elastic deformation of the elastic body 46.

[0064] Furthermore, when vibrations are input in the vertical direction, the dynamic damper 10 also exerts a vibration damping effect. That is, when vertical vibrations are input between the inner shaft member 42 and the outer cylindrical member 44, the vibrations are transmitted to the mounting bracket 14 attached to the inner shaft member 42, and the mass member 16, which is elastically connected to the mounting bracket 14 via the connecting rubber elastic body 18, is excited in the vertical direction. As a result, the vibration damping effect of the dynamic damper 10 is exerted on the vehicle body (not shown) via the inner shaft member 42, thereby improving the vibration state of the vehicle body. The vibration damping effect of the dynamic damper 10 is exerted when vibrations to be damped are input by tuning the resonant frequency of the mass-spring system, in which the mass member 16 is the mass component and the connecting rubber elastic body 18 is the spring component, to the frequency of the vibration to be damped.

[0065] By providing covering rubber portions 38a and 38b to cover both the upper and lower sides of the mass member 16, the center of gravity of the mass member 16 and the elastic center of the rubber elastic body including the connecting rubber elastic body 18 and the covering rubber portions 38a and 38b can be brought closer to each other in the axial direction. As a result, stable elastic support of the mass member 16 is achieved, and the displacement of the mass member 16 during vibration input is stabilized, thereby stably obtaining the desired vibration damping performance. In particular, in this embodiment, both axial end faces of the connecting rubber elastic body 18 are located axially outward from both axial end faces of the thickened portion 34, and the axial dimension of the connecting rubber elastic body 18 is made larger than the axial dimension of the thickened portion 34. Furthermore, the covering rubber portions 38a and 38b are integrally formed by extending directly radially from both the upper and lower end portions of the connecting rubber elastic body 18 that are located axially outward from the thickened portion 34. In this manner, the connecting rubber elastic body 18 is positioned over the entire opposing surface between the mass member 16 (thick-walled portion 34) and the peripheral wall portion 20 of the mounting bracket 14, and is also arranged to extend axially on both sides beyond this opposing surface. As a result, stable support for the mass member 16 is ensured, and the spring characteristics of the mass member 16 can be adjusted and secured using the covering rubber portions 38a and 38b. Furthermore, stress concentration in the connecting rubber elastic body 18 and the covering rubber portions 38a and 38b is reduced, which can improve durability.

[0066] In this embodiment, since the inner circumference of the mass member 16 is a thickened portion 34, the center of gravity of the mass member 16 is set on the inner circumference side supported by the connecting rubber elastic body 18. As a result, the displacement of the mass member 16 during vibration input is made more stable, further stabilizing the desired vibration damping performance. In addition, the thickened portion 34 in this embodiment is formed by thickening the outer circumference of the mass member 16 so that it protrudes upward in the axial direction. As a result, the support spring center of the mass member 16 is set slightly upward in the axial direction relative to the center of gravity of the mass member 16, and as a result, excessive interference with the brace fitting 56 due to the upward displacement of the mass member 16 can be suppressed.

[0067] In this embodiment, the covering rubber portion 38a extends to cover the outer circumferential surface of the thickened portion 34 of the mass member 16. As a result, the thickened portion 34 of the mass member 16 is elastically supported over a wide area, thereby stabilizing the vibration damping performance by stabilizing the displacement of the mass member 16 during vibration input.

[0068] The axial length of the connecting rubber elastic body 18 is shorter than the axial length of the peripheral wall portion 20 of the mounting bracket 14. This efficiently secures space on the outer circumference side of the peripheral wall portion 20 to allow for elastic deformation of the connecting rubber elastic body 18 and displacement of the mass member 16, and also makes it easier to avoid interference with other members arranged around the dynamic damper 10.

[0069] Since the upper part of the peripheral wall portion 20 of the mounting bracket 14 is a tapered portion 24 that becomes smaller in diameter towards the top, interference between the mounting bracket 14 and other surrounding components is easily avoided. In particular, since the upper part of the tapered portion 24 that protrudes upward from the connecting rubber elastic body 18 has a small diameter, interference between the mounting bracket 14 and other surrounding components is less likely to be a problem.

[0070] The material casting marks 40, which are traces of the gate used to inject rubber material during the molding of the connecting rubber elastic body 18, are located at the outer peripheral end of the covering rubber portion 38a, away from the connecting rubber elastic body 18, which is prone to affecting the tuning and vibration damping characteristics of the dynamic damper 10. As a result, the material casting marks 40 are less likely to affect the vibration damping characteristics and frequency tuning of the dynamic damper 10, and the desired vibration damping performance can be stably obtained.

[0071] Incidentally, the flange-shaped projection 26 of the mounting bracket 14 is located below the mass member 16, and its outer peripheral end is located on the outer peripheral side of the inner peripheral end of the mass member 16. As a result, even if the connecting rubber elastic body 18 breaks and the mass member 16 falls onto the mounting bracket 14, the mass member 16 will catch on the flange-shaped projection 26 of the mounting bracket 14, thus configuring a fail-safe mechanism that prevents the mass member 16 from detaching from the mounting bracket 14. Therefore, even if the connecting rubber elastic body 18 breaks while the dynamic damper 10 is mounted on a vehicle, the mass member 16 can be prevented from falling to the road surface. Furthermore, if the connecting rubber elastic body 18 breaks, upward separation of the mass member 16 is prevented by contact between the mass member 16 and the brace bracket 56, thus preventing separation of the mass member 16 on both the upper and lower sides.

[0072] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, a tapered portion is not essential in the peripheral wall portion of the mounting bracket, and the peripheral wall portion may extend straight with a substantially constant diameter along its entire axial length. Also, the flange-like projection 26 of the peripheral wall portion can be omitted, and if a flange-like projection is provided, it does not have to constitute a fail-safe mechanism. A stepped portion is not essential in the bottom wall portion of the mounting bracket, and for example, the entire bottom wall portion may be a flat plate.

[0073] The thickened portion of the mass body is not mandatory; the entire radial section may have a uniform thickness. Furthermore, depending on the shape of the brace fitting and the space available for the dynamic damper, the outer periphery may also be made thicker. Additionally, the thickened portion of the mass body may be made thicker by protruding on the opposite side of the member mount.

[0074] The rubber covering portion of the connecting rubber elastic body only needs to hold the inner circumference of the mass body from both axial sides, and does not necessarily need to cover the outer circumference of the thick-walled portion of the mass body. The connecting rubber elastic body may be fixed to the peripheral wall of the mounting bracket at a position away from the tapered portion.

[0075] The axial end faces of the connecting rubber elastic body may be located axially inward from the axial end faces of the thickened portion of the mass member. Therefore, the minimum axial dimension of the connecting rubber elastic body may be smaller than the axial dimension of the mass member in the thickened portion. [Explanation of Symbols]

[0076] 10 Dynamic damper (first embodiment) 12 Member Mount 14 Mounting brackets 16 Mass members (mass bodies) 18. Linked rubber elastic body 20 Peripheral wall section 22 Bottom wall section 24 Tapered section 26 Flange-shaped projection 28 bolt insertion holes 30 Step section 32 Mounting surface 34 Thick wall part 36. Buffer rubber layer 38a, 38b Covered rubber part 40 Material casting marks 42 Inner shaft member 44 Outer cylindrical member 46 Elastic body 48 Flange section 50 Reduced diameter part 52 slit holes 54 Stopper rubber 56 Brace fittings 58 Bolt insertion holes 60 Step section 62 Mounting surface 64 Standing piece 66 Stopper contact area 68 volts 70 Spacer 72 Suspension Member 74 mounting holes

Claims

1. A dynamic damper mounted on a cylindrical member mount, which has an inner shaft member and an outer cylindrical member connected by an elastic material, A mounting bracket having a cylindrical peripheral wall portion, which is positioned on one axial end side of the inner shaft member of the member mount and fixed to the inner shaft member such that the peripheral wall portion extends in the direction of the central axis, An annular mass body is disposed at a distance from the outer circumference of the peripheral wall portion of the mounting bracket, A connecting rubber elastic body connects the peripheral wall portion and the mass body between opposing surfaces perpendicular to the axis. It has, The connecting rubber elastic body has a covering rubber portion integrally formed on its outer circumference, which extends to both axial end faces of the mass body and holds the inner circumference of the mass body from both axial sides. The axial dimension of the connecting rubber elastic body is smaller than the axial dimension of the peripheral wall portion. Dynamic damper.

2. The axial end faces of the connecting rubber elastic body between the circumferential wall portion and the mass body, in the direction perpendicular to the axis, are located axially outward from the axial end faces of the inner circumferential portion of the mass body. The dynamic damper according to claim 1, wherein the covering rubber portion is integrally formed by the axial portions on both sides of the connecting rubber elastic body extending outward.

3. The dynamic damper according to claim 1 or 2, wherein the inner circumference of the mass body is provided with a thickened portion having a larger axial dimension than the outer circumference.

4. The dynamic damper according to claim 3, wherein, at the axial end face of the mass body, the covering rubber portion extends further outward than the thickened portion and covers the outer edge of the thickened portion.

5. The dynamic damper according to claim 1 or 2, wherein the mounting bracket and the mass body are vulcanized and bonded to the connecting rubber elastic body.

6. The dynamic damper according to claim 1 or 2, wherein the material casting marks during molding are located on the outer peripheral edge portion of the covering rubber part in the connecting rubber elastic body.

7. The mounting bracket is provided with a flange-shaped projection that extends outward from the axial end located on the axial side opposite to the member mount in the peripheral wall portion, The dynamic damper according to claim 1 or 2, wherein the outer peripheral end of the flange-like projection is located on the outer peripheral side of the mass body than the inner peripheral end of the mass body, thereby constituting a fail-safe mechanism that prevents the mass body from detaching due to the breakage of the connecting rubber elastic body.

8. The circumferential wall portion is a tapered portion in which the axial end side located on the member mount side gradually decreases in diameter toward the axial outward direction. The dynamic damper according to claim 1 or 2, wherein the connecting rubber elastic body is also fixed to the outer circumferential surface of the tapered portion.

9. The mounting bracket is provided with a flat bottom wall portion that extends inward from the axial end located on the member mount side in the peripheral wall portion. The dynamic damper according to claim 1 or 2, wherein the bottom wall portion is provided with an annular stepped portion on its outer circumference, and the inner circumference side of the stepped portion is a mounting surface that protrudes in the axial direction.

10. A brace fitting extending perpendicular to the axis is provided at one axial end of the inner shaft member in the member mount. The outer edge of the brace fitting has an annular rising piece that is located on the outer circumference side of the covering rubber portion of the connecting rubber elastic body and extends axially toward the mass body, The outer axial surface of the brace fitting has an annular concave step portion in the radial middle section, and the inner circumference side of the concave step portion is a mounting surface that is concave in the axial direction. The dynamic damper according to claim 9, wherein the mounting surface of the mounting bracket is superimposed on the mounting surface, and the stepped portion of the mounting bracket is aligned perpendicular to the axis with respect to the concave stepped portion.

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