Dynamic damper

Abstract

A dynamic damper (10) to be mounted on a tubular element bearing (12) comprising an inner shaft element (42) and an outer tubular element (44) connected by an elastic body (46). The dynamic damper (10) comprises: an attachment (14) comprising a tubular circumferential wall (20) and arranged at an axial end face of the inner shaft element (42) for attachment, the circumferential wall (20) extending in a central axis direction; an annular mass body (16) spaced radially outward from the circumferential wall (20); and an elastic connecting rubber body (18) connecting the circumferential wall (20) and the mass body (16) in an axis-perpendicular direction.A rubber cover (38a, 38b) is formed integrally with the elastic connecting rubber body (18) and provides a receptacle such that it covers a radially inner section of the mass body (16) from axially opposite sides. An axial dimension of the elastic connecting rubber body (18) is smaller than that of the circumferential wall (20).

Description

General state of the art 1. Technical field

[0001] The present invention relates to a dynamic damper which is to be mounted on an element bearing which supports a suspension element of a vehicle in a vibration-damping manner. 2. Description of the relevant state of the art

[0002] Traditionally, a component bearing equipped with a dynamic damper has been discussed for the purpose of improving the vibration damping support performance of a suspension element and the like. For example, it is conceivable to use a dynamic damper as disclosed in JP 2023-054685 A. Summary

[0003] The dynamic damper with the conventional structure, as revealed in JP 2023-054685 A, is comparatively large. Particularly in newer vehicles where installation space is limited, there is still room for improvement to achieve a reduction in size while reliably maintaining vibration damping performance.

[0004] Furthermore, in such a conventional dynamic damper, the mass is lengthened in the vertical direction to ensure a sufficient area for pressing it into a press-fit sleeve (a cylindrical section). Additionally, it is difficult to stably support the mass with an elastic connecting element located at its lower end. This makes it challenging to guarantee the durability of the elastic connecting element and also makes it difficult to avoid a negative impact on vibration damping performance due to excessive mass oscillation.

[0005] It is therefore an object of the present invention to provide a dynamic damper with a novel structure which is able to reliably maintain the vibration damping performance with a compact structure, and to improve the durability and vibration damping support performance of the suspension element and the like.

[0006] Preferred embodiments for realizing the present invention are described below. However, each preferred embodiment described below is exemplary and can be combined with one another in a suitable manner. Furthermore, a plurality of elements described in each preferred embodiment can be identified and adopted as independently as possible, or they can be suitably combined with any element described in other preferred embodiments. In this way, various further preferred embodiments can be realized in the present disclosure without being limited to those described below.

[0007] A first preferred embodiment provides a dynamic damper configured to be mounted on a tubular element bearing, the tubular element bearing comprising an inner shaft element and an outer tube element connected by an elastic body, wherein the dynamic damper has: an attachment part or- Fitting with a tubular circumferential wall, wherein the attachment is arranged on an axial end side of the inner shaft element of the tubular element bearing and fixed to the inner shaft element, wherein the tubular circumferential wall extends in a central axis direction; an annular mass body which is radially spaced outwards from the tubular circumferential wall of the attachment; and an elastic connecting rubber body which connects opposite surfaces of the tubular circumferential wall and the annular mass body in an axis-perpendicular direction, wherein a cover rubber is formed integrally with a radially outer section of the elastic connecting rubber body, wherein the cover rubber extends over axially opposite end surfaces of the annular mass body and provides a receptacle orThe support is provided such that it covers a radially inner section of the annular mass body from axially opposite sides, and wherein an axial dimension of the elastic connecting rubber body is smaller than that of the tubular circumferential wall.

[0008] According to the dynamic damper, which is structured according to the present preferred embodiment, the mass body is directly attached to the elastic connecting rubber body. In this way, a press-fit sleeve and a press-fit process are unnecessary in the conventional structure, thereby simplifying the structure and reducing its size.

[0009] Furthermore, the rubber cover is designed to cover the radially inner section of the mass from the axially opposite sides, and the radially inner section of the mass is embedded within the elastic connecting rubber body and the rubber cover, which are formed as a single unit. This reliably establishes a mounting area and a mounting force for the mass relative to the elastic connecting rubber body and the rubber cover. Additionally, the mass's center of gravity and the elastic center of the connecting rubber body can be aligned axially, thus achieving stable support for the mass. This stabilizes the mass during vibration input and improves vibration damping performance.

[0010] Additionally, in the section where the mass is attached to the elastic connecting rubber body, the cover rubber is provided on the axially opposite sides. Even if the position of the mass deviates slightly in the axial direction during the forming of the elastic connecting rubber body, the attachment area of ​​the elastic connecting rubber body and the cover rubber to the mass remains stable. Therefore, the desired capability can be achieved reliably.

[0011] Furthermore, the axial dimension of the elastic connecting rubber body is smaller than that of the circumferential wall. This effectively provides a space that allows for elastic deformation of the elastic connecting rubber body and displacement of the mass body in the radially outer region of the circumferential wall. Interference with other components arranged around the dynamic damper can thus be easily avoided.

[0012] A second preferred embodiment provides the dynamic damper according to the first preferred embodiment, wherein axially opposite end surfaces of the elastic connecting rubber body are located between the opposing surfaces of the tubular circumferential wall and the annular mass body in the axis-perpendicular direction in an axial direction with respect to the axially opposite end surfaces of the radially inner section of the annular mass body, and axially opposite side sections of the elastic connecting rubber body extend radially outwards, so that they form the cover rubber in one piece.

[0013] According to the dynamic damper, which is structured according to the present preferred embodiment, it is possible to reliably and effectively maintain the mounting area and the mounting force or strength of the mass body on the elastic connecting rubber body by means of the cover rubber, to improve the vibration damping performance by stabilizing the displacement of the mass body during a vibration input, to avoid interference or impairment with other components by reliably saving space, and the like. Furthermore, it is also possible to effectively maintain the elastic properties of the elastic connecting rubber body, including the cover rubber, in a limited and confined space, as well as to improve the durability of the elastic connecting rubber body, including the cover rubber.

[0014] A third preferred embodiment provides the dynamic damper according to the first or second preferred embodiment, wherein the radially inner section of the annular mass body comprises a thick-walled part whose axial dimension is larger than that of a radially outer section of the annular mass body.

[0015] According to the dynamic damper structured in the present preferred embodiment, the mass distribution of the mass body is greater on the radially inner side, which corresponds to the side closer to the support position through the elastic connecting rubber body, than on the radially outer side. In this way, a stabilization of a displacement or deflection of the mass body during a vibration input can be achieved, thereby improving the vibration damping performance.

[0016] A fourth preferred embodiment provides the dynamic damper according to the third preferred embodiment, wherein the cover rubber extends on an axial end surface of the annular mass body to a radially outer side of the thick-walled part and covers a radially outer end of the thick-walled part.

[0017] According to the dynamic damper, which is structured according to the present preferred embodiment, the thick-walled part of the mass body with a larger mass is covered and supported by the elastic connecting rubber body and the cover rubber extending to the radial outer surface. This makes the displacement of the mass body more stable during a vibration input, thereby further improving the vibration damping performance.

[0018] A fifth preferred embodiment provides the dynamic damper according to one of the first to fourth preferred embodiments, wherein the attachment part and the annular mass body are connected to the elastic connecting rubber body by vulcanization.

[0019] According to the dynamic damper, which is structured according to the present preferred embodiment, the joining process can be eliminated by connecting the attachment part and the mass body through vulcanization during the vulcanization molding of the elastic connecting rubber body, and a high connection strength can be obtained in a simple manner.

[0020] A sixth preferred embodiment provides the dynamic damper according to one of the first to fifth preferred embodiments, wherein a radially outer end section of the cover rubber includes a material casting track during the molding of the elastic connecting rubber body.

[0021] According to the dynamic damper, which is structured according to the present preferred embodiment, the material casting track is unlikely to affect the properties of the elastic connecting rubber body provided on the radially inner side of the cover rubber, thus stabilizing the performance of the elastic connecting rubber body, which is likely to influence the mass-spring system. This allows the vibration damping performance to be effectively exerted during a vibration input.

[0022] A seventh preferred embodiment provides the dynamic damper according to one of the first to sixth preferred embodiments, wherein the attachment part comprises a flange-shaped projection extending radially outward from an axial end of the tubular circumferential wall, the axial end being located on an axially opposite side to the tubular element bearing, and a radially outer end of the flange-shaped projection being arranged on a radially outer side of a radially inner end of the annular mass body to form a fail-safe mechanism which prevents the annular mass body from detaching due to a break or tear of the elastic connecting rubber body.

[0023] According to the dynamic damper, which is structured according to the present preferred embodiment, the mass body is captured by the flange-shaped projection of the attachment even if the elastic connecting rubber body tears, thereby preventing disturbances such as the mass body becoming detached and falling onto the road surface, or the like.

[0024] An eighth preferred embodiment provides the dynamic damper according to one of the first to seventh preferred embodiments, wherein the tubular circumferential wall comprises a tapered part at another axial end, which is located on one side of the tubular element bearing, wherein the tapered part gradually decreases in diameter towards the outside in an axial direction, and the elastic connecting rubber body is also attached to an outer circumferential surface of the tapered part.

[0025] According to the dynamic damper, which is structured according to the present preferred embodiment, the circumferential wall of the attachment decreases in diameter at the tapered section, which facilitates the avoidance of interference or impairment with other components in the vicinity. Furthermore, the elastic connecting rubber body is attached up to the outer circumferential surface of the tapered section, which makes it easier to maintain a larger attachment area or surface for the elastic connecting rubber body on the attachment.

[0026] A ninth preferred embodiment provides the dynamic damper according to one of the first to eighth preferred embodiments, wherein the attachment part comprises a base wall having a flat plate shape and extending radially inwards from another axial end of the tubular circumferential wall, the other axial end being located on one side of the tubular element bearing, and wherein a radially outer section of the base wall comprises an annular stepped part, and a radially inner side of the annular stepped part comprises a mounting surface projecting in an axial direction.

[0027] According to the dynamic damper, which is structured according to the present preferred embodiment, the area for attaching the elastic connecting rubber body to the base wall of the attachment is defined by the stepped section provided at the base wall of the attachment. This prevents burrs of the elastic connecting rubber body from extending to the attachment surface on the radially inner side of the stepped section.

[0028] A tenth preferred embodiment provides the dynamic damper according to the ninth preferred embodiment, which is configured to be mounted on the tubular element bearing comprising a support connection part extending in the axis-perpendicular direction at an axial end of the inner shaft element, wherein the support connection part comprises: an annular raised portion formed on a radially outer edge of the support connection part, wherein the annular raised portion is arranged on a radially outer side with respect to the cover rubber of the elastic connecting rubber body, while extending in the axial direction towards the annular mass body; and an annular concave stepped portion.Step section which is provided at a radially middle section of an axially outer surface of the support connection part, such that a radially inner side of the annular concave step section has an attachment target surface which is recessed in the axial direction, wherein the attachment surface of the attachment part overlaps or is superimposed with the attachment target surface, so that the annular step section of the attachment part is aligned with the annular concave step section in the axis perpendicular direction.

[0029] According to the dynamic damper, which is structured according to the present preferred embodiment, the attachment part and the support connection part can be aligned in the axis perpendicular direction by the stepped part and the concave stepped part. Since the stepped part prevents the elastic connecting rubber body from extending onto the mounting surface of the attachment part, it prevents the rubber from being inserted between the overlapping surfaces of the mounting surface of the attachment part and the target mounting surface of the support connection part, thereby securely fixing the attachment part and the support connection part.

[0030] According to the present disclosure, the dynamic damper to be mounted on the element bearing is able to reliably maintain the vibration damping performance with a compact structure and to improve the durability and vibration damping support performance of the suspension element or the like. Brief description of the illustrations

[0031] The foregoing and / or further tasks, features and advantages of the invention will become more apparent from the following description of a practical embodiment with reference to the accompanying figures, in which the same reference numerals denote the same elements, and wherein: Fig. 1 a vertical sectional view of a dynamic damper according to a first practical embodiment of the present disclosure in a mounted state on an element bearing; Fig. 2 a top view of an attachment of the in Fig. The dynamic damper shown in section 1 is; Fig. 3 a bottom view of the in Fig. 2 of the attachment shown; Fig. 4 a top view of a mass element of the in Fig. The dynamic damper shown in section 1 is; and Fig. 5 a bottom view of the in Fig. The mass element shown in section 4 is shown. Detailed description

[0032] A practical embodiment of the present disclosure is described below with reference to the illustrations.

[0033] Fig. Figure 1 shows a dynamic damper 10 according to a first practical embodiment of the present disclosure in a state attached to an element bearing 12. The dynamic damper 10 has a structure in which an attachment part 14 and a mass element 16 serving as a mass body are connected by an elastic connecting rubber body 18. In the following description, the vertical direction generally refers to the vertical direction in Fig. 1, which corresponds to the axial direction.

[0034] As in the Fig. 1, Fig. 2 to Fig. As shown in Figure 3, the attachment 14 has an overall inverted cylindrical shape with a base and is made of metal, such as iron and an aluminum alloy. The attachment 14 has a structure in which a base wall 22 projects radially inwards from the upper end of a circumferential wall 20, which has an approximately cylindrical shape.

[0035] The upper end of the circumferential wall 20 of the attachment 14 has a tapered section 24, the diameter of which gradually decreases towards the top. The angle of inclination of the tapered section 24 can vary in the vertical direction, but in the present practical embodiment, the diameter of the tapered section 24 narrows towards the top at an approximately constant angle of inclination. Furthermore, the lower end of the circumferential wall 20 of the attachment 14 is provided with a flange-shaped projection 26, which extends radially outwards. In the present practical embodiment, the flange-shaped projection 26 is formed by bending the lower end of the circumferential wall 20 radially outwards, so that the lower end of the circumferential wall 20 is widened downwards. The vertically central section of the circumferential wall 20 has a straight cylindrical shape that extends approximately parallel to the vertical direction.

[0036] The base wall 22 of the attachment part 14 has a generally annular disc shape, which extends approximately perpendicular to the vertical direction, and is penetrated vertically in the central section by a screw insertion hole 28. The base wall 22 comprises an annular stepped section 30 in its radially outer section, and the radially inner side of the stepped section 30 has a mounting surface 32 that projects upwards with respect to its radially outer side. The mounting surface 32 is a flat surface whose upper and lower surfaces extend perpendicular to the vertical direction.

[0037] As in the Fig. 1, Fig. 4 and Fig. As shown in Figure 5, the mass element 16 generally has an annular shape and extends ring-shaped throughout with an approximately constant cross-sectional shape. The mass element 16 is preferably made of a metallic material with a high specific gravity, such as iron. The inner diameter of the mass element 16 is larger than the outer diameter of the vertically central section of the circumferential wall 20 of the attachment 14. Furthermore, the inner diameter of the mass element 16 is preferably smaller than the outer diameter of the flange-shaped projection 26 of the attachment 14. The radially outer end of the flange-shaped projection 26 is preferably located on the radially outer side of the radially inner end of the mass element 16 to form a fail-safe mechanism described later.

[0038] The radially inner section of the mass element 16 comprises a thick-walled part 34 whose vertical dimension (thickness) is larger than that of the radially outer section of the mass element 16. The lower surface of the thick-walled part 34 is in common plane with the radially outer section, while its upper surface projects further upward than the upper surface of the radially outer section. That is, the thick-walled part 34 is designed to be thick, such that it projects upward relative to the radially outer section. The radial width dimension of the thick-walled part 34 is determined such that interference with or impairment of a raised section 64 of a subsequently described support connection part 56 is avoided, and in the present practical embodiment, it is no greater than half the total radial width dimension of the mass element 16.Furthermore, the height of the projection of the thick-walled part 34 is set upwards in such a way as to avoid any impairment of the support connection part 56 described later, and in the present practical embodiment this is not greater than half the thickness dimension of the radially outer section of the mass element 16.

[0039] The mass element 16 is attached externally around the circumferential wall 20 of the attachment part 14 such that it is radially spaced outwards from the circumferential wall 20 of the attachment part 14, and the circumferential wall 20 of the attachment part 14 and the mass element 16 are elastically connected to each other by the elastic connecting rubber body 18. The elastic connecting rubber body 18 has an overall annular shape and is positioned radially between the circumferential wall 20 of the attachment part 14 and the mass element 16. The attachment part 14 and the mass element 16 can be attached to the elastic connecting rubber body 18 after molding by joining, welding, or other means. In the present practical embodiment, however, they are vulcanized to the elastic connecting rubber body 18 during molding.Therefore, in the present practical embodiment, the elastic connecting rubber body 18 has the form of a one-piece molded vulcanization component which accommodates the attachment part 14 and the mass element 16. In particular, with regard to the elastic connecting rubber body 18, the inner circumferential surface thereof is vulcanized to the circumferential wall 20 of the attachment part 14, while the outer circumferential surface thereof is vulcanized to the mass element 16.

[0040] The upper end of the elastic connecting rubber body 18 extends to the tapered portion 24 of the circumferential wall 20 of the attachment part 14 and is also vulcanized to the outer circumferential surface of the tapered portion 24. At the circumferential wall 20 of the attachment part 14, the upper part of the tapered portion 24, which forms the upper end, and the flange-shaped projection 26, which forms the lower end, project outwards in the upper and lower directions, respectively, with respect to the elastic connecting rubber body 18. Accordingly, the vertical dimension of the elastic connecting rubber body 18 is smaller than that of the circumferential wall 20. The upper surface of the flange-shaped projection 26 of the attachment part 14 is covered with a damping rubber layer 36, which is integrally formed with the elastic connecting rubber body 18.

[0041] With respect to the elastic connecting rubber body 18 arranged radially between the circumferential wall 20 of the attachment part 14 and the mass element 16, the vertically opposite end surfaces of the elastic connecting rubber body 18 are located on the outside in the axial direction, opposite to the vertically opposite end surfaces of the thick-walled part 34 of the mass element 16. Accordingly, the vertical dimension of the elastic connecting rubber body 18 is larger than that of the thick-walled part 34. The elastic connecting rubber body 18 is integrally provided with cover rubbers 38a, 38b through its upper and lower opposing end sections, which extend radially outwards. In the present practical embodiment, the elastic connecting rubber body 18 extends radially in the radial direction between the outer circumferential surface of the circumferential wall 20 of the attachment part 14 and the inner circumferential surface of the mass element 16 (including the axial extension section).

[0042] The cover rubber 38a extends radially outward from the upper end of the radially outer end of the elastic connecting rubber body 18 and spreads over the upper end surface of the thick-walled part 34 of the mass element 16, thereby covering the upper surface of the thick-walled part 34. The cover rubber 38a extends to the radially outer side of the thick-walled part 34 of the mass element 16 and covers the outer circumferential surface of the thick-walled part 34. The outer diameter dimension of the cover rubber 38a is smaller than the inner diameter dimension of the raised part 64 of the support connecting part 56 described later. The cover rubber 38b extends radially outward from the lower end of the radially outer end of the elastic connecting rubber body 18 and spreads over the lower end surface of the thick-walled part 34 of the mass element 16, thereby covering the lower end surface of the thick-walled part 34.The cover rubber 38b is spaced upwards from the damping rubber layer 36, which covers the upper surface of the flange-shaped projection 26.

[0043] The thick-walled part 34, corresponding to the radially inner section of the mass element 16, is vulcanized over a large area to the elastic connecting rubber body 18 and the cover rubbers 38a, 38b, which are formed integrally with the elastic connecting rubber body 18, in order to be inserted therein. The radially outer section of the mass element 16 projects radially outwards with respect to the cover rubbers 38a, 38b. In the present practical embodiment, the cover rubber 38a, which covers the upper side of the mass element 16, extends further outwards in the radial direction than the cover rubber 38b, which covers the lower side of the mass element 16. The cover rubber 38a, which projects further outwards, includes a casting groove 40.The material casting track 40 corresponds to the track of a gate for casting a rubber material into the cavity of the mold during the forming of the elastic connecting rubber body 18 and is located at the radially outer end section of the cover rubber 38a. In the present practical embodiment, the material casting track 40 projects at the corner where the upper surface and the outer circumferential surface of the cover rubber 38a intersect.

[0044] The elastic connecting rubber body 18 is not attached to the mounting surface 32 of the base wall 22 of the attachment part 14. Specifically, during the molding of the elastic connecting rubber body 18, the attachment part 14 is placed in the mold. The position at which the elastic connecting rubber body 18 is formed, including any burrs during molding, is defined using the step section 30, which is provided on the radially outer side of the mounting surface 32 of the base wall 22. This prevents the rubber material from reaching the mounting surface 32 on the radially inner side of the step section 30. Therefore, both the upper and lower surfaces of the mounting surface 32 are exposed, without any rubber covering.

[0045] In the dynamic damper 10, the mass element 16 is directly attached to the elastic connecting rubber body 18. This eliminates the need for a press-fit sleeve to attach the mass element 16, and the press-fitting process can be omitted. This allows for a simple and compact structure of the dynamic damper 10 or similar devices by reducing the number of parts.

[0046] In the present practical embodiment, the elastic connecting rubber body 18 is vulcanized to the attachment 14 and the mass element 16, and the elastic connecting rubber body 18 takes the form of a one-piece molded vulcanized component that accommodates the attachment 14 and the mass element 16. Therefore, it is not necessary to join the attachment 14 and the mass element 16 in a separate process after the forming of the elastic connecting rubber body 18, thus simplifying manufacturing. Furthermore, since the attachment 14 and the mass element 16 are vulcanized to the elastic connecting rubber body 18, a high bond strength can be achieved. The elastic connecting rubber body 18, the damping rubber layer 36, and the cover rubbers 38a, 38b are formed in one piece by vulcanization.

[0047] Since the radially inner section of the mass element 16 has the thick-walled part 34 with a large axial dimension, it is easy to obtain a large bonding surface between the radially inner section of the mass element 16 and the elastic connecting rubber body 18. Furthermore, the thick-walled part 34, which corresponds to the radially inner section of the mass element 16, is covered on the axially opposite sides by the cover rubbers 38a, 38b and embedded between them, so that it is inserted between them. This ensures a large bonding surface between the mass element 16 and the elastic connecting rubber body 18, thereby reliably and stably maintaining the high bonding force.

[0048] Even if the position of the mass element 16 deviates slightly in the axial direction during the forming of the elastic connecting rubber body 18, the cover rubbers 38a, 38b are provided on the axially opposite sides of the mass element 16, so that the fastening surface or fastening area of ​​the elastic connecting rubber body 18 and the cover rubbers 38a, 38b on the mass element 16 is maintained stably. In this way, the desired capability, such as the fastening force, can be achieved in a stable manner.

[0049] The elastic connecting rubber body 18, attached to the circumferential wall 20 of the attachment part 14, extends to the outer circumferential surface of the tapered section 24 of the circumferential wall 20. This allows the attachment area of ​​the elastic connecting rubber body 18 to the attachment part 14 to be secured over a larger area, thereby ensuring a more stable and greater fastening force.

[0050] The dynamic damper 10 of the above construction is attached to the element bearing 12, as shown in Fig. Figure 1 shows the element bearing 12 as a tubular vibration damping device with a structure in which an inner shaft element 42 and an outer tube element 44 are connected by an elastic body 46.

[0051] The inner shaft element 42 has a thick-walled, cylindrical shape with a small diameter and extends straight in the vertical direction. The central hole of the inner shaft element 42 has a larger diameter than the screw insertion hole 28 formed in the attachment part 14 of the dynamic damper 10. The outer diameter dimension of the lower end surface of the inner shaft element 42 is preferably not larger than that of the mounting surface 32 of the base wall 22 of the attachment part 14.

[0052] The outer tube element 44 has a thin-walled, approximately cylindrical shape with a large diameter and comprises a flange part 48 formed integrally at its lower end. The flange part 48 has an annular disc shape and projects radially outwards. The minimum inner diameter of the outer tube element 44 is larger than the outer diameter of the inner shaft element 42. The upper end of the outer tube element 44 has a constriction 50, the diameter of which decreases upwards.

[0053] The inner shaft element 42, inserted into the outer tube element 44, provides the elastic body 46 radially between the inner shaft element 42 and the outer tube element 44. The elastic body 46 has an approximately cylindrical shape overall, and its inner circumferential surface is vulcanized to the outer circumferential surface of the inner shaft element 42, while its outer circumferential surface is vulcanized to the inner circumferential surface of the outer tube element 44. The elastic body 46 can have a constant cross-sectional shape over its entire circumference. In the present practical embodiment, however, through holes 52 are provided on opposite sides along an axis in the diametrical direction, with the inner shaft element 42 inserted between them, thereby adjusting the spring ratio in the two perpendicular directions.A stop rubber 54 is integrally formed with the elastic body 46 on the lower surface of the flange portion 48 of the outer pipe element 44, so that the latter projects downwards. By performing a diameter reduction process on the outer pipe element 44 after the vulcanization molding of the elastic body 46, the stress caused by thermal shrinkage of the elastic body 46 after molding is mitigated, thereby improving the durability of the elastic body 46. Furthermore, during the diameter reduction process on the outer pipe element 44, the upper end of the elastic body 46 is pre-compressed radially by further reducing the diameter of the outer pipe element 44 to form a constriction 50. This results in a further improvement in the durability of the elastic body 46.

[0054] The support connection part 56, which extends approximately orthogonally to the vertical direction, overlaps the lower surface of the inner shaft element 42. The support connection part 56 has an overall approximately annular disc shape and includes a screw insertion hole 58 formed in its diametrical center. The support connection part 56 is a high-strength component made of a metallic material. The support connection part 56 has a stepped section 60 in its radially central portion, with the radially inner side of the stepped section 60 located above its radially outer side. In this configuration, the radially inner side of the stepped section 60 is recessed upwards in the support connection part 56, and the lower surface of the recessed portion has a mounting target surface 62.

[0055] A tubular, downwardly projecting, raised section 64 is formed integrally with the radially outer end of the support connection section 56. The raised section 64 increases the deformation stiffness of the annular disc-shaped support connection section 56. The section located radially between the stepped section 60 and the raised section 64 in the support connection section 56 has a stop section 66, which is vertically opposite the flange section 48 of the outer tubular element 44. The stop section 66 extends approximately perpendicular to the vertical direction.

[0056] The dynamic damper 10 is attached to the element bearing 12, which is constructed as described above. In particular, the mounting surface 32 of the base wall 22 of the attachment part 14 overlaps or is superimposed from below with the mounting target surface 62 of the support connection part 56, and the attachment part 14 is arranged below the inner shaft element 42, with the circumferential wall 20 extending in the central axis direction of the inner shaft element 42. The inner shaft element 42, the support connection part 56, and the attachment part 14 are fixed to one another by a screw 68, which is inserted through the screw insertion hole 28 of the attachment part 14, the screw insertion holes 58 of the support connection part 56, and the central hole of the inner shaft element 42. In this way, the attachment part 14 of the dynamic damper 10 is attached to the inner shaft element 42 of the element bearing 12.In the present practical embodiment, a spacer 70 is inserted between the head of the screw 68 and the base wall 22 of the attachment part 14.

[0057] In the state attached to the inner shaft element 42, the support connection part 56 projects radially outwards with respect to the inner shaft element 42, and the stop part 66 of the support connection part 56 faces the flange part 48 of the outer tube element 44 from below. The stop rubber 54 projecting from the flange part 48 of the outer tube element 44 is in advance contact with the stop part 66 of the support connection part 56, and the stop rubber 54 is vertically compressed between the flange part 48 and the stop part 66. The support connection part 56 can be fixed to the inner shaft element 42, for example, by welding or by other means after the vulcanization molding of the elastic body 46, with the upper surface of the recessed section on the radially inner side of the step part 60 overlapping or superimposed with the lower end surface of the inner shaft element 42.

[0058] The base wall 22 of the attachment part 14 has a smaller diameter than the step section 60 of the support connection part 56 and is inserted into the radial interior of the step section 60. Therefore, the step section 30 of the base wall 22 and the step section 60 of the support connection part 56 align the attachment part 14 with the support connection part 56 to a certain extent in the radial direction, thus facilitating easy positioning of the attachment part 14 before it is fixed to the support connection part 56 and the inner shaft element 42. In the present practical embodiment, the entire lower surface of the radially inner side of the step section 60 of the support connection part 56 has the mounting target surface 62.For example, by providing a concave stepped portion on the radially inner side of the support connector 56, which is recessed upwards such that the radially inner side of the concave stepped portion is located above its radially outer side, the lower surface of the recessed section can encompass the mounting target surface. In this case, it is desirable, for example, to specify the inner diameter dimension of the concave stepped portion of the support connector 56 as equal to or slightly larger than the outer diameter dimension of the stepped portion 30 provided on the base wall 22 of the attachment 14 of the dynamic damper 10.This also makes it possible to align the attachment part 14 and the support connection part 56 more precisely in the radial direction before fixing them, by inserting the stepped part 30 of the attachment part 14 into the concave stepped part of the support connection part 56 in such a way that the mounting surface 32 of the attachment part 14 and the target mounting surface of the support connection part 56 overlap each other.

[0059] The raised portion 64 of the support connection part 56 is located on the radially outer side with respect to the cover rubber 38a and projects downwards towards the radially outer section of the mass element 16. The raised portion 64 is spaced upwards from the radially outer section of the mass element 16, which is thinner than the radially inner section, thus allowing displacement of the mass element 16 in the vertical direction.

[0060] In the dynamic damper 10, mounted on the element bearing 12 as described above, the raised portion 64 of the support connection part 56 is located on the radially outer side with respect to the thick-walled part 34 of the mass element 16. The raised portion 64 is located on the radially outer side with respect to the rubber cover 38a, which covers the outer circumferential surface of the thick-walled part 34 of the mass element 16. The projecting distal end surface (the lower end surface) of the raised portion 64 is spaced upwards from the upper surface of the radially outer section of the mass element 16. The mass element 16 is thicker in its radially inner section than in its radially outer section, thereby preventing interference with the raised portion 64 and simultaneously ensuring a large mass.The raised section 64 projects to such a position that, viewed radially, it overlaps the cover rubber 38a, which covers the upper surface of the thick-walled part 34 of the mass element 16. In this arrangement, the radially outer section of the support connection part 56 has a cover section that covers the upper part of the thick-walled part 34, which projects upwards from the radially inner section of the mass element 16, and the cover rubber 38a, which covers the upper part of the thick-walled part 34, such that it is spaced upwards and outwards. This protects the upper part of the thick-walled part 34 and the cover rubber 38a from impact by foreign objects from above and from the radial outside, as well as from thermal radiation, thus effectively preventing deterioration or damage to the cover rubber 38a and, consequently, to the elastic connecting rubber body 18.

[0061] The element bearing 12 is attached to the vehicle by, for example, attaching the inner shaft element 42 to a side of the vehicle body (not shown) using the screw 68, while the outer tube element 44 is fixed by pressing it into a mounting hole 74 of a suspension element 72.

[0062] When a vertical vibration acts on the element bearing 12 mounted on the vehicle via the inner shaft element 42 and the outer tube element 44, a vibration damping effect is observed due to the elastic deformation of the elastic body 46.

[0063] During the application of vertical vibration, the dynamic damper 10 also exhibits a vibration damping effect. Specifically, when the vertical vibration is introduced via the inner shaft element 42 and the outer tube element 44, the vibration is transmitted to the attachment 14, which is mounted on the inner shaft element 42. Consequently, the mass element 16, which is elastically connected to the attachment 14 via the elastic connecting rubber body 18, is set into vibration in the vertical direction. In this way, the dynamic damper 10 exerts a vibration damping effect on the vehicle body (not shown) via the inner shaft element 42, thereby improving the vibration state of the vehicle body.The vibration damping effect of the dynamic damper 10 is exerted during the input of the target vibration to be damped by tuning the resonance frequency of the mass-spring system, in which the mass element 16 corresponds to the mass component and the elastic connecting rubber body 18 corresponds to the spring component, to the frequency of the target vibration to be damped.

[0064] By positioning the cover rubbers 38a, 38b to cover both the top and bottom of the mass element 16, the center of gravity of the mass element 16 and the elastic center of the elastic rubber body, which comprises the elastic connecting rubber body 18 and the cover rubbers 38a, 38b, can be brought closer together in the axial direction. This configuration provides stable elastic support for the mass element 16 and stabilizes the displacement or deflection of the mass element 16 during vibration input, thereby maintaining the desired vibration damping performance.In the present practical embodiment, the axially opposite end surfaces of the elastic connecting rubber body 18 are arranged externally in the axial direction with respect to the axially opposite end surfaces of the thick-walled part 34, such that the axial dimension of the elastic connecting rubber body 18 is larger than that of the thick-walled part 34. The cover rubbers 38a, 38b are formed in one piece such that they extend radially directly from the upper and lower end sections of the elastic connecting rubber body 18, which are located on the axially opposite outer surfaces with respect to the thick-walled part 34.In this way, the elastic connecting rubber body 18 is positioned over the entirety of the opposing surfaces of the mass element 16 (the thick-walled part 34) and the circumferential wall 20 of the attachment part 14, and extends beyond these opposing surfaces to the axially opposite sides. This provides stable support for the mass element 16 and allows the spring properties of the mass element 16 to be adjusted or reliably maintained using the cover rubbers 38a, 38b. Furthermore, the concentration of stresses in the elastic connecting rubber body 18 and the cover rubbers 38a, 38b is reduced, thereby improving durability.

[0065] In the present practical embodiment, since the radially inner section of the mass element 16 has the thick-walled part 34, the center of gravity of the mass element 16 is fixed on the radially inner side, which is supported by the elastic connecting rubber body 18. This makes the displacement of the mass element 16 more stable during vibration input, thereby further stabilizing the desired vibration damping performance. Furthermore, in the present practical embodiment, the thick-walled part 34 is designed such that it projects axially upwards with respect to the radially outer section of the mass element 16, thus giving it a thick wall. Accordingly, the center of the support spring of the mass element 16 is slightly offset upwards in the axial direction with respect to the center of gravity of the mass element 16.This can suppress excessive interference between the mass element 16 and the support connection part 56 due to an upward displacement or the like.

[0066] In the present practical embodiment, the rubber cover 38a expands such that it provides coverage up to the outer circumferential surface of the thick-walled part 34 of the mass element 16. In this configuration, the thick-walled part 34 of the mass element 16, which has a large mass, is elastically supported over a large area, thereby stabilizing the vibration damping performance through a stable displacement of the mass element 16 during vibration input.

[0067] The axial length of the elastic connecting rubber body 18 is shorter than that of the circumferential wall 20 of the attachment part 14. This effectively provides space on the radially outer side of the circumferential wall 20 to allow elastic deformation of the elastic connecting rubber body 18 and displacement of the mass element 16, thereby easily avoiding interference or impairment of other components arranged around the dynamic damper 10.

[0068] Since the upper part of the circumferential wall 20 of the attachment 14 has the tapered section 24, whose diameter decreases upwards, it is easy to avoid interference between the attachment 14 and other components in the environment. In particular, the upper part of the tapered section 24, which projects upwards from the elastic connecting rubber body 18, has a smaller diameter. Thus, interference between the attachment 14 and other components in the environment is less likely to be a problem.

[0069] The material casting track 40, which corresponds to the track of the gate for casting a rubber material during the molding of the elastic connecting rubber body 18, is located at the radially outer end of the cover rubber 38a, away from the elastic connecting rubber body 18, which likely influences the tuning and vibration damping properties of the dynamic damper 10. Accordingly, it is less likely that the material casting track 40 influences the vibration damping properties and frequency tuning of the dynamic damper 10, thereby ensuring the desired vibration damping performance in a stable manner.

[0070] The flange-shaped projection 26 of the attachment part 14 is located below the mass element 16, and its radially outer end is situated on the radially outer side of the radially inner end of the mass element 16. In this configuration, even if the elastic connecting rubber body 18 breaks and the mass element 16 falls away from the attachment part 14, the mass element 16 is retained by the flange-shaped projection 26 of the attachment part 14, thus forming a fail-safe mechanism that prevents the mass element 16 from detaching from the attachment part 14. Therefore, in the case of the dynamic damper 10 mounted on the vehicle, even if the elastic connecting rubber body 18 breaks, the mass element 16 is prevented from falling onto the road surface.Here, if the elastic connecting rubber body 18 breaks, separation of the mass element 16 upwards is prevented by contact between the mass element 16 and the support connection part 56, so that separation of the mass element 16 is prevented on both the upper and lower sides.

[0071] A practical embodiment of the present disclosure has been described in detail above; however, the present disclosure is not limited to these specific descriptions. For example, a tapered portion in the circumferential wall of the attachment is not essential, and the circumferential wall may extend with an approximately constant diameter over its entire axial length. Furthermore, the flange-shaped projection 26 of the circumferential wall may be omitted, or if the flange-shaped projection is provided, it need not constitute the fail-safe mechanism. In addition, the stepped portion in the base wall of the attachment is not essential, and, for example, the entire base wall may have a flat, plate-like shape.

[0072] The thick-walled portion of the mass body is not strictly necessary and can have a constant thickness in the radial direction throughout. Additionally, depending on the design of the support connection, the installation space for the dynamic damper, or similar components, the radially outer section of the mass body can be thick-walled. Furthermore, the thick-walled portion of the mass body can project laterally opposite the element bearing, thus exhibiting its thickness.

[0073] It would be acceptable if the rubber covers of the elastic connecting rubber body held the radially inner section of the mass body in such a way as to cover it from the axially opposite sides, and did not necessarily need to be provided in such a way as to provide coverage up to the outer circumferential surface of the thick-walled part of the mass body. The elastic connecting rubber body may be attached to the circumferential wall of the attachment at a location away from the tapered section.

[0074] The axially opposite end surfaces of the elastic connecting rubber body can be arranged internally in the axial direction with respect to the axially opposite end surfaces of the thick-walled part of the mass element. Thus, the minimum axial dimension of the elastic connecting rubber body can be smaller than the axial dimension of the mass element in the thick-walled part. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-054685 A [0002, 0003]

Claims

Dynamic damper (10) configured to be mounted on a tubular element bearing (12), the tubular element bearing (12) comprising an inner shaft element (42) and an outer tubular element (44) connected by an elastic body (46), the dynamic damper (10) comprising: an attachment (14) comprising a tubular circumferential wall (20), the attachment (14) being arranged at an axial end face of the inner shaft element (42) of the tubular element bearing (12) and fixed to the inner shaft element (42), the tubular circumferential wall (20) extending in a central axis direction; an annular mass body (16) spaced radially outward from the tubular circumferential wall (20) of the attachment (14);and an elastic connecting rubber body (18) which connects opposite surfaces of the tubular circumferential wall (20) and the annular mass body (16) in an axis-perpendicular direction, wherein a cover rubber (38a, 38b) is formed integrally with a radially outer section of the elastic connecting rubber body (18), wherein the cover rubber (38a, 38b) extends over axially opposite end surfaces of the annular mass body (16) and provides a support such that it covers a radially inner section of the annular mass body (16) from axially opposite sides, and an axial dimension of the elastic connecting rubber body (18) is smaller than that of the tubular circumferential wall (20). Dynamic damper (10) according to claim 1, wherein axially opposite end surfaces of the elastic connecting rubber body (18) lie between the opposing surfaces of the tubular circumferential wall (20) and the annular mass body (16) in the axis-perpendicular direction in an axial direction with reference to the axially opposite end surfaces of the radially inner section of the annular mass body (16), and axially opposite side sections of the elastic connecting rubber body (18) extend radially outwards, so that they form the cover rubber (38a, 38b) in one piece. Dynamic damper (10) according to claim 1 or 2, wherein the radially inner section of the annular mass body (16) comprises a thick-walled part (34) whose axial dimension is larger than that of a radially outer section of the annular mass body (16). Dynamic damper (10) according to claim 3, wherein the cover rubber (38a) extends on an axial end surface of the annular mass body (16) to a radially outer side of the thick-walled part (34) and covers a radially outer end of the thick-walled part (34). Dynamic damper (10) according to one of claims 1 to 4, wherein the attachment part (14) and the annular mass body (16) are connected to the elastic connecting rubber body (18) by vulcanization. Dynamic damper (10) according to one of claims 1 to 5, wherein a radially outer end section of the cover rubber (38a) comprises a material casting track (40) during the molding of the elastic connecting rubber body (18). Dynamic damper (10) according to one of claims 1 to 6, wherein the attachment part (14) comprises a flange-shaped projection (26) which extends radially outwards from an axial end of the tubular circumferential wall (20), the axial end being located on an axially opposite side to the tubular element bearing (12), and a radially outer end of the flange-shaped projection (26) being arranged on a radially outer side of a radially inner end of the annular mass body (16) to form a fail-safe mechanism which prevents the annular mass body (16) from coming loose due to a tear in the elastic connecting rubber body (18). Dynamic damper (10) according to one of claims 1 to 7, wherein the tubular circumferential wall (20) comprises a tapered part (24) at another axial end, which is located on one side of the tubular element bearing (12), wherein the tapered part (24) gradually decreases in diameter towards the outside in an axial direction, and the elastic connecting rubber body (18) is also attached to an outer circumferential surface of the tapered part (24). Dynamic damper (10) according to one of claims 1 to 8, wherein the attachment part (14) comprises a base wall (22) which has a flat plate shape and extends radially inwards from another axial end of the tubular circumferential wall (20), wherein the other axial end is located on one side of the tubular element bearing (12), and a radially outer section of the base wall (22) comprises an annular step part (30), and a radially inner side of the annular step part (30) has a mounting surface (32) which projects in an axial direction. Dynamic damper (10) according to claim 9, which is configured such that it is to be mounted on the tubular element bearing (12) which comprises a support connection part (56) which extends in the axis perpendicular direction at an axial end of the inner shaft element (42), wherein the support connection part (56) comprises: an annular raised part (64) formed on a radially outer edge of the support connection part (56), wherein the annular raised part (64) is arranged on a radially outer side with respect to the cover rubber (38a) of the elastic connecting rubber body (18), while extending in the axial direction towards the annular mass body (16);and an annular concave step section, which is provided at a radially central section of an axially outer surface of the support connection part (56), such that a radially inner side of the annular concave step section has a mounting target surface (62) which is recessed in the axial direction, wherein the mounting surface (32) of the attachment part (14) is superimposed on the mounting target surface (62), so that the annular step section (30) of the attachment part (14) is aligned with the annular concave step section in the axis perpendicular direction.

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