JP2019211009A - Dynamic damper - Google Patents

Abstract

To provide a dynamic damper improved in a degree of freedom in natural frequency while preventing falling of a mass body.SOLUTION: A dynamic damper includes a cylindrical member, a projecting portion, a mass body, an elastic connecting portion, and a fastening member, and an inner peripheral surface of the mass body includes a pair of first opposite faces opposed to each other in a first direction through a shaft center of the cylindrical member, and a pair of second opposite faces opposed to each other in a second direction orthogonal to the first direction through the shaft center. An interval in the second direction, of the pair of second opposite faces is larger than an interval in the first direction of the pair of first opposite faces, and a part of the projecting portion is positioned at an outer side in a direction perpendicular to an axis, of the pair of first opposite faces at any position of the relative rotation of the mass body to the cylindrical member about the shaft center, in an axial view of the cylindrical member.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dynamic damper, and more particularly to a dynamic damper that can improve the degree of freedom of the natural frequency while preventing the mass body from falling off.

  In vehicles such as automobiles and industrial machines, there are many harmful vibrations such as engine vibrations and resonances that occur during running (operation). Therefore, dynamic dampers are used to suppress these harmful vibrations. May be incorporated. The dynamic damper includes, for example, a cylindrical cylindrical member attached to a mating member that is a target for suppressing vibration, and a cylindrical mass body that coaxially surrounds the cylindrical member, and is configured from a rubber-like elastic body. There exists what was connected with the elastic connection part (patent document 1).

  The technology of Patent Document 1 prevents the mass body from falling off due to the breakage of the elastic connecting portion by making the inner diameter of the mass body smaller than the outer diameter of the head of the bolt for attaching the cylindrical member to the counterpart member. doing. In order to set the spring constant of the elastic connecting portion, which is a parameter for determining the natural frequency of the dynamic damper, it is conceivable to adjust the axial perpendicular direction dimension of the elastic connecting portion by adjusting the inner diameter of the mass body.

Japanese Utility Model Publication 4-35255

  However, in the above prior art, the mass body has an inner diameter smaller than the outer diameter of the bolt head to prevent the mass body from falling off. For example, the mass body has a standardized bolt head size. The inner diameter is limited. That is, the degree of freedom in setting the natural frequency of the dynamic damper is low with respect to the size of the head.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a dynamic damper capable of improving the degree of freedom in setting the natural frequency while preventing the mass body from falling off.

  In order to achieve this object, a dynamic damper according to the present invention includes a cylindrical member having a first end portion and a second end portion in the axial direction, and a tension projecting outward in a direction perpendicular to the axial direction of the cylindrical member at the first end portion. A protruding mass, a cylindrical mass disposed on the second end side of the projecting portion, the inner circumferential surface being arranged at a predetermined interval from the outer circumferential surface of the cylindrical member, and the mass An elastic connecting portion composed of a rubber-like elastic body that connects the inner peripheral surface and the outer peripheral surface of the cylindrical member, and the second end portion of the cylindrical member that is inserted into the cylindrical member and fastened to the counterpart member A fastening member, and an inner circumferential surface of the mass body sandwiches the shaft center between a pair of first opposing surfaces facing each other in a first direction with the shaft center of the cylindrical member interposed therebetween, A pair of second facing surfaces facing each other in a second direction orthogonal to the first direction, and the pair of second facing surfaces The distance in the second direction is greater than the distance in the first direction between the pair of first opposing surfaces, and the mass body is rotated around the axis with respect to the cylinder member when viewed in the axial direction of the cylinder member. In any of the positions rotated relative to each other, a part of the protruding portion is located outside the pair of first opposing surfaces in the direction perpendicular to the axis.

  According to the dynamic damper of claim 1, the inner peripheral surface of the mass body has a pair of first opposing surfaces having a relatively small interval in the opposing direction (first direction) and an interval in the opposing direction (second direction). A relatively large pair of second opposing surfaces. As viewed in the axial direction of the cylindrical member, the outer side of the pair of first opposed surfaces in the direction perpendicular to the axis is relatively small at any position where the mass body is rotated relative to the cylindrical member around the axial center of the cylindrical member. A part of the overhanging part is located in As a result, it is possible to prevent the mass body from falling off the cylindrical member due to breakage of the elastic connecting portion or the like.

  Further, the interval between the pair of second opposing surfaces can be set regardless of the interval between the pair of first opposing surfaces set according to the size of the overhanging portion or the like. That is, since the distance between the pair of second opposing surfaces can be set relatively freely, the degree of freedom of the spring constant in the second direction of the elastic connecting portion can be improved. As a result, it is possible to improve the degree of freedom in setting the natural frequency of the dynamic damper while preventing the mass body from falling off.

  According to the dynamic damper of claim 2, in any cross section including the shaft center, the outline of the inner peripheral surface of the mass body and the shaft center are parallel over the entire length in the axial direction. This makes it easier to form the inner circumferential surface of the mass body than when a portion of the inner circumferential surface of the mass body is provided with an irregularity, and elastically connects from the inner circumferential surface of the mass body during vibration. The force acting on the part can be easily predicted. As a result, in addition to the effect of the first aspect, the mass body can be easily molded and the natural frequency of the dynamic damper can be easily set.

  According to the dynamic damper of claim 3, the interval in the first direction of the inner peripheral surface of the mass body is from the position of the maximum interval in the first direction of the pair of first opposing surfaces in the second direction when viewed in the axial direction. It gets smaller gradually with distance. This makes it easier to form the inner circumferential surface of the mass body and provides elastic connection from the inner circumferential surface of the mass body during vibration compared to the case where unevenness or the like is provided on a part of the inner circumferential surface of the mass body. The force acting on the part can be easily predicted. As a result, in addition to the effect of the first or second aspect, the mass body can be easily formed and the natural frequency of the dynamic damper can be easily set.

  According to the dynamic damper of the fourth aspect, since the distance in the first direction between the pair of first opposing surfaces is constant over the entire length in the second direction, the mass body can be easily formed. Further, since the distance between the pair of first opposing surfaces in the first direction is constant, when the mass body vibrates in the second direction with respect to the cylindrical member, the force in the second direction from the pair of first opposing surfaces to the elastic connecting portion. Can be made difficult to act. As a result, in addition to the effect of any one of claims 1 to 3, it is possible to easily set the natural frequency in the second direction of the dynamic damper.

It is sectional drawing of the dynamic damper in 1st Embodiment. (A) is a side view of a mass body. (B) is a side view of the mass body in 2nd Embodiment. (A) is a side view of the mass body in a 3rd embodiment. (B) is a side view of the mass body in 4th Embodiment.

  Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. First, the dynamic damper 1 in the first embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of the dynamic damper 1 including the axis C of the cylindrical member 10. In the present specification, the direction of the axis C is referred to as an axial direction, and the direction orthogonal to the axis C is referred to as an axis perpendicular direction.

  As shown in FIG. 1, the dynamic damper 1 is a device for suppressing harmful vibrations such as vibrations generated during running (operation) of vibrations of an engine or the like in a vehicle such as an automobile or an industrial machine. The dynamic damper 1 is attached to a counterpart member 2 that vibrates. The counterpart member 2 is, for example, an engine mount bracket and a plate-like member.

  The dynamic damper 1 connects the cylindrical member 10, the cylindrical mass body 20 in which the inner peripheral surface 21 is arranged with a predetermined interval from the outer peripheral surface 13 of the cylindrical member 10, and the mass body 20 and the cylindrical member 10. The elastic connection part 40 and the fastening member 50 which fastens the cylindrical member 10 to the other party member 2 are provided.

  The cylindrical member 10 is a cylindrical metal member centered on the axis C. The tubular member 10 includes a first end portion 11 and a second end portion 12 in the axial direction. The mass body 20 is a thick cylindrical metal member that surrounds the cylindrical member 10 coaxially. The axis of the mass body 20 and the axis C of the cylindrical member 10 are the same.

  In any cross section including the axis C, the outline of the inner peripheral surface 21 of the mass body 20 and the axis C are parallel over the entire length in the axial direction. In addition, when the chamfering is given to the axial direction both ends of the mass body 20 with the axial direction full length in this specification, the axial direction full length except the chamfer part is shown.

  The elastic connection part 40 is a member comprised from a rubber-like elastic body. The elastic connecting portion 40 is vulcanized and bonded to the inner peripheral surface 21 of the mass body 20 and the outer peripheral surface 13 of the cylindrical member 10 to connect the inner peripheral surface 21 and the outer peripheral surface 13.

  The outer peripheral surface and both end surfaces in the axial direction of the mass body 20 are covered with an elastic film 43 that is an integrally molded product with the elastic connecting portion 40. By covering the mass body 20 with the elastic film 43, it is possible to reduce an impact sound when the mass body 20 vibrates and collides with the counterpart member 2 or the like.

  The axial dimension of the mass body 20 covered with the elastic film 43 is set smaller than the axial dimension of the cylindrical member 10. The mass body 20 covered with the elastic film 43 is located on the inner side in the axial direction than the first end portion 11 and the second end portion 12 of the cylindrical member 10. Thereby, the contact with the other party member 2 or the fastening member 50, and the elastic film 43 can be suppressed. Thereby, it can suppress that the vibration of the axis-perpendicular direction of the mass body 20 with respect to the cylinder member 10 resulting from the contact is prevented.

  The fastening member 50 includes a flange bolt 51 and a nut 55. The flange bolt 51 includes a hexagonal head 52 as viewed in the axial direction, a disk-shaped protruding portion (flange) 53 provided on one end of the head 52 in the axial direction, and a protruding portion between the head 52. A shaft portion 54 that protrudes in the axial direction from the overhang portion 53 with the portion 53 interposed therebetween is provided. The overhang portion 53 is a disk-shaped portion that protrudes a predetermined amount outward from the head 52 in the direction perpendicular to the axis. The overhang portion 53 projects outward in the direction perpendicular to the axis from the outer peripheral surface 13 of the tubular member 10 at the first end portion 11 of the tubular member 10.

  In order to attach the tubular member 10 to the mating member 2, first, the shaft portion 54 is inserted into the tubular member 10 from the first end portion 11 side, and the shank portion 54 coming out from the second end portion 12 is replaced with the mating member. 2 is inserted into a through hole 2a penetrating in the plate thickness direction. By attaching a nut 55 to the shaft portion 54 inserted into the through hole 2 a of the counterpart member 2, the cylindrical member 10 is sandwiched in the axial direction by the counterpart member 2 and the overhang portion 53, and the cylindrical member 10 is clamped by the fastening member 50. The member 10 is fastened to the counterpart member 2. The mass body 20 is disposed on the second end 12 side of the overhang portion 53.

  Next, the relationship between the inner peripheral surface 21 of the mass body 20 and the overhang portion 53 will be described with reference to FIG. FIG. 2A is a side view of the mass body 20. In FIG. 2A, the outline of the overhang portion 53 is shown by a two-dot chain line.

  As shown in FIG. 2A, the inner peripheral surface 21 of the mass body 20 is formed in an elliptical shape when viewed in the axial direction. The inner peripheral surface 21 has a pair of first opposing surfaces 22 facing each other in the first direction A with the axis C (tubular member 10) interposed therebetween, and a pair of first opposing surfaces 22 in the second direction B with the axis C interposed therebetween. A pair of second opposing surfaces 23 facing each other. The first direction A and the second direction B are directions orthogonal to each other in the direction perpendicular to the axis.

  The distance L2 in the second direction B between the pair of second facing surfaces 23 is larger than the distance L1 in the first direction A between the pair of first facing surfaces 22. The maximum distance L11 (minor axis) in the first direction A of the pair of first opposing surfaces 22 is an interval L1 on a straight line (minor axis) that passes through the axis C and is parallel to the first direction A. The maximum distance L21 (major axis) in the second direction B of the pair of second facing surfaces 23 is an interval L2 on a straight line (major axis) that passes through the axis C and is parallel to the second direction B.

  The maximum distance L11 between the pair of first opposing surfaces 22 is smaller than the outer diameter R1 of the overhang portion 53. The intersection of the major axis and the minor axis of the elliptical inner peripheral surface 21 is the axis C. Therefore, when viewed in the axial direction, the pair of first opposing surfaces having a distance L1 smaller than the distance L2 at any position where the mass body 20 is relatively rotated around the axis C with respect to the cylindrical member 10 (see FIG. 1). A part of the overhanging portion 53 is located on the outside in the direction perpendicular to the axis 22. As shown in FIGS. 1 and 2A, since the mass body 20 is located on the second end portion 12 side of the overhang portion 53, the mass body is separated from the cylindrical member 10 due to the breakage of the elastic connecting portion 40 or the like. It is possible to prevent 20 from falling off.

  Here, in the case of using a mass body having an approximately constant inner diameter, the entire inner diameter of the mass body is made smaller than the outer shape R1 of the overhanging portion 53 in order to prevent the mass body from falling off the cylindrical member 10. Must be set. However, when the flange bolt 51 standardized by JIS or the like is used, the inner diameter of the mass body is restricted by the size (outer diameter R1) and shape of the overhang portion (flange) 53 of the flange bolt 51.

  Further, even when a non-standard overhang 53 that has been used for a dynamic damper or the like is used, the inner diameter of the mass body is restricted by the size and shape of the overhang 53. Then, it is not always possible to freely change the spring constant of the elastic connecting part 40 by adjusting the inner diameter of the mass body to change the dimension of the elastic connecting part 40 in the direction perpendicular to the axis. That is, the degree of freedom in setting the natural frequency of the dynamic damper is low with respect to the size and shape of the overhang portion 53.

  In contrast, in the present embodiment, the interval L2 between the pair of second opposing surfaces 23 is set regardless of the interval L1 between the pair of first opposing surfaces 22 set according to the size and shape of the overhanging portion 53. it can. That is, since the distance L2 can be set relatively freely, the degree of freedom in the dimension in the second direction B of the elastic connecting portion 40 between the second facing surface 23 and the cylindrical member 10 can be improved. As a result, the degree of freedom of the spring constant of the elastic connecting portion 40 in the second direction B can be improved, so that the degree of freedom in setting the natural frequency of the dynamic damper 1 can be improved.

  As described above, the pair of first opposing surfaces 22 having a small interval L1 and the pair of second opposing surfaces 23 having a large interval L2 prevent the mass body 20 from falling off and It is possible to achieve both improvement in the degree of freedom in setting the natural frequency of the dynamic damper 1 with respect to the size and shape. These coexistences are possible even when, for example, the overhanging portion 53 standardized by JIS or the like, or the non-standard overhanging portion 53 that has been used before, is newly used. Compared with the case of manufacturing, the cost for the overhanging portion 53 can be reduced.

  Since the natural frequency in the second direction B of the dynamic damper 1 is easily set relatively freely, it is preferable to set the main vibration direction of the dynamic damper 1 in the second direction B. Thereby, it is possible to easily set the natural frequency of the dynamic damper 1 in the main vibration direction while preventing the mass body 20 from falling off.

  The natural frequency of the dynamic damper 1 also depends on how the elastic connecting portion 40 is constrained to the inner peripheral surface 21, that is, the shape of the inner peripheral surface 21 that applies force to the elastic connecting portion 40 during vibration. The distance in the first direction A of the inner peripheral surface 21 of the mass body 20 gradually decreases as the distance from the position of the maximum distance L11 in the second direction B increases when viewed in the axial direction. In other words, since the inner peripheral surface 21 is elliptical, the interval in the second direction B of the inner peripheral surface 21 of the mass body 20 gradually decreases as it moves away from the position of the maximum interval L21 in the first direction A as viewed in the axial direction. Thereby, compared with the case where an unevenness | corrugation etc. are provided in a part of the circumferential direction of the internal peripheral surface 21, it can be easy to estimate the force which acts on the elastic connection part 40 from the internal peripheral surface 21 at the time of a vibration. As a result, the natural frequency of the dynamic damper 1 can be easily set.

  Moreover, in any cross section including the axis C, the outline of the inner peripheral surface 21 and the axis C are parallel over the entire axial length. Thereby, compared with the case where an unevenness | corrugation etc. are provided in a part of axial direction of the internal peripheral surface 21, the force which acts on the elastic connection part 40 from the internal peripheral surface 21 at the time of a vibration can be estimated easily. As a result, the natural frequency of the dynamic damper 1 can be easily set.

  Here, a method for forming the mass body 20 will be described. First, the mass body 20 having an approximate shape is formed by casting, forging, cutting, or the like. Thereafter, the inner peripheral surface 21 is cut or ground so that the natural frequency of the dynamic damper 1 becomes an appropriate set value, the shape of the inner peripheral surface 21 is adjusted in detail, and the mass body 20 is formed. To do.

  As described above, the interval in the first direction A of the inner peripheral surface 21 gradually decreases as the distance from the position of the maximum interval L11 in the second direction B increases when viewed in the axial direction. Moreover, in any cross section including the axis C, the outline of the inner peripheral surface 21 and the axis C are parallel over the entire axial length. In these cases, compared to the case where unevenness or the like is provided on a part of the inner peripheral surface 21, it is particularly easy to perform cutting or grinding for adjusting the inner peripheral surface 21, and the mass body 20 can be easily formed. it can.

  Moreover, since the shape of the inner peripheral surface 21 is adjusted by cutting or grinding, the inner peripheral surface 21 can be made smooth. Thereby, the dispersion | variation from the design value of the axial perpendicular direction dimension between the outer peripheral surface 13 of the cylinder member 10 and the inner peripheral surface 21 of the mass body 20 can be made small, and the dispersion | variation in the spring constant of the elastic connection part 40 can be made small. . Moreover, since the inner peripheral surface 21 is smooth, it is possible to reduce variations in the force that acts on the elastic connecting portion 40 from the inner peripheral surface 21 during vibration. As a result, variations in the natural frequency of the dynamic damper 1 can be easily suppressed.

  If the second direction B is the main vibration direction of the dynamic damper 1, the smoothness of the pair of second opposing surfaces 23 greatly affects the natural frequency of the dynamic damper 1 in the main vibration direction. Therefore, the natural vibration of the dynamic damper 1 can be obtained without subjecting the pair of second opposing surfaces 23 to cutting or grinding to smooth the second opposing surfaces 23 and cutting or grinding the other inner peripheral surface 21. The variation in the number can be sufficiently suppressed. Therefore, the amount of cutting for suppressing variation in the natural frequency of the dynamic damper 1 in the main vibration direction can be reduced.

  Next, a second embodiment will be described with reference to FIG. In the first embodiment, the case where the inner peripheral surface 21 of the mass body 20 is elliptical when viewed in the axial direction has been described. On the other hand, 2nd Embodiment demonstrates the case where the internal peripheral surface 61 of the mass body 60 is an oval shape seeing in an axial direction. In addition, about the part same as 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted.

  The dynamic damper according to the second embodiment is the same as the dynamic damper 1 according to the first embodiment except that the shape of the inner peripheral surface 61 of the mass body 60 is different. FIG. 2B is a side view of the mass body 60 in the second embodiment. In FIG. 2B, the outline of the overhang portion 53 is shown by a two-dot chain line.

  As shown in FIG. 2B, the inner peripheral surface 61 of the mass body 60 of the dynamic damper in the second embodiment is formed in an oval shape when viewed in the axial direction. The inner circumferential surface 61 has a pair of first opposing surfaces 62 facing each other in the first direction A with the axis C (tubular member 10) interposed therebetween, and a pair of first opposing surfaces 62 in the second direction B with the axis C interposed therebetween. A pair of opposing second opposing surfaces 63.

  The distance L4 in the second direction B between the pair of second facing surfaces 63 is larger than the distance L3 in the first direction A between the pair of first facing surfaces 62. The interval L3 is constant over the entire length in the second direction B. That is, the maximum interval in the first direction A between the pair of first opposing surfaces 62 is the interval L3. The interval L3 is smaller than the outer diameter R1 of the overhang portion 53. Therefore, when viewed in the axial direction, a part of the protruding portion 53 is formed outside the pair of first opposing surfaces 62 in the direction perpendicular to the axis at any position where the mass body 60 is relatively rotated around the axis C with respect to the cylindrical member 10. Is located.

  Thereby, similarly to 1st Embodiment, it can prevent that the mass body 60 falls from the cylinder member 10 by the fracture | rupture etc. of the elastic connection part 40. FIG. Furthermore, since the distance L4 between the pair of second facing surfaces 63 can be set relatively freely regardless of the distance L3 between the pair of first facing surfaces 62 set according to the size and shape of the overhang portion 53, the mass The degree of freedom in setting the natural frequency of the dynamic damper having the body 60 can be improved.

  The interval in the first direction A of the inner peripheral surface 61 gradually decreases as it moves away from the first facing surface 62 (position of the interval L3) in the second direction B when viewed in the axial direction. Further, the distance L3 between the pair of first opposing surfaces 62 is constant over the entire length in the second direction B. Further, in any cross section including the axial center C, the outline of the inner peripheral surface 61 and the axial center C are parallel over the entire length in the axial direction. In these cases, as described in the first embodiment, the mass body 60 can be easily formed and the dynamic damper having the mass body 60 can be formed as compared with the case where unevenness is provided on a part of the inner peripheral surface 61. It is easy to set the natural frequency.

  In particular, since the distance L3 is constant over the entire length in the second direction B, when the mass body 60 vibrates in the second direction B with respect to the cylindrical member 10, the pair of first opposing surfaces 62 are connected to the elastic connecting portion 40. The force in the two directions B can be made difficult to act. As a result, the natural frequency in the second direction B of the dynamic damper having the mass body 60 can be set more easily.

  Furthermore, since the distance L3 between the pair of first opposing surfaces 62 is constant over the entire length in the second direction B, it is possible to easily set the axis perpendicular dimension between the pair of first opposing surfaces 62 and the cylindrical member 10. Thereby, since the spring constant of the elastic connecting part 40 in the first direction A can be easily set, the natural frequency in the first direction A of the dynamic damper having the mass body 60 can be set more easily.

  Next, a third embodiment will be described with reference to FIG. In the first embodiment, the case where the inner peripheral surface 21 of the mass body 20 is elliptical when viewed in the axial direction has been described. On the other hand, 3rd Embodiment demonstrates the case where the internal peripheral surface 71 of the mass body 70 is rectangular shape seeing to an axial direction. In addition, about the part same as 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted.

  The dynamic damper in the third embodiment is different from the dynamic damper 1 in the first embodiment only in the shape of the inner peripheral surface 71 of the mass body 70 and the outer shape of the overhanging portion 74, and the other configurations are as follows. Are the same. Fig.3 (a) is a side view of the mass body 70 in 3rd Embodiment. In FIG. 3A, the outline of the overhang portion 74 is shown by a two-dot chain line.

  As shown in FIG. 3A, the inner peripheral surface 71 of the mass body 70 of the dynamic damper in the third embodiment is formed in a rectangular shape when viewed in the axial direction. The inner peripheral surface 71 has a pair of first opposing surfaces 72 facing each other in the first direction A with the axis C (tubular member 10) interposed therebetween, and a pair of first opposing surfaces 72 in the second direction B with the axis C interposed therebetween. A pair of opposing second opposing surfaces 73. The first facing surface 72 and the second facing surface 73 are each one side of a rectangle.

  The distance L6 in the second direction B between the pair of second facing surfaces 73 is larger than the distance L5 in the first direction A between the pair of first facing surfaces 72. The interval L5 is constant over the entire length in the second direction B. The interval L6 is constant over the entire length in the first direction A.

  The overhanging portion 74 is formed in a regular hexagonal shape when viewed in the axial direction. The diameter R2 of the inscribed circle of the overhanging portion 74 is larger than the distance L5 between the pair of first opposing surfaces 72. Therefore, when viewed in the axial direction, a part of the overhanging portion 74 is formed outside the pair of first opposing surfaces 72 in the direction perpendicular to the axis at any position where the mass body 70 is relatively rotated around the axis C with respect to the cylindrical member 10. Is located.

  Thereby, similarly to 1st Embodiment, it can prevent that the mass body 70 falls from the cylinder member 10 by the fracture | rupture etc. of the elastic connection part 40. FIG. Furthermore, regardless of the distance L5 between the pair of first opposing surfaces 72 set according to the size (diameter R2 of the inscribed circle) and the shape of the overhanging portion 73, the interval L6 between the pair of second opposing surfaces 73 is set. Since it can be set relatively freely, the degree of freedom in setting the natural frequency of the dynamic damper having the mass body 70 can be improved.

  The distance L5 between the pair of first opposing surfaces 72 is constant over the entire length in the second direction B. Further, the distance L6 between the pair of second facing surfaces 73 is constant over the entire length in the first direction A. Further, in any cross section including the axial center C, the outline of the inner peripheral surface 71 and the axial center C are parallel over the entire length in the axial direction. In these cases, as described in the first embodiment, the mass body 70 can be easily formed and the dynamic damper having the mass body 70 can be formed as compared with the case where unevenness is provided on a part of the inner peripheral surface 71. It is easy to set the natural frequency.

  In particular, since the distance L5 is constant over the entire length in the second direction B, when the mass body 70 vibrates in the second direction B with respect to the cylindrical member 10, the pair of first opposing surfaces 72 are connected to the elastic connecting portion 40. The force in the two directions B can be made difficult to act. As a result, the natural frequency in the second direction B of the dynamic damper having the mass body 70 can be easily set. Similarly, since the distance L6 is constant over the entire length in the first direction A, the natural frequency in the first direction A of the dynamic damper having the mass body 70 can be easily set.

  Furthermore, since the distance L5 between the pair of first opposing surfaces 72 is constant over the entire length in the second direction B, it is possible to easily set the axis perpendicular dimension between the pair of first opposing surfaces 72 and the cylindrical member 10. Thereby, the spring constant in the first direction A of the elastic coupling portion 40 can be easily set, so that the natural frequency in the first direction A of the dynamic damper having the mass body 70 can be easily set. Similarly, since the distance L6 between the pair of second facing surfaces 73 is constant over the entire length in the first direction A, the natural frequency in the second direction B of the dynamic damper having the mass body 70 can be easily set.

  Next, a fourth embodiment will be described with reference to FIG. In the first embodiment, the case where the inner peripheral surface 21 of the mass body 20 is elliptical when viewed in the axial direction has been described. On the other hand, 4th Embodiment demonstrates the case where the internal peripheral surface 81 of the mass body 80 is hexagonal shape seeing to an axial direction. In addition, about the part same as 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted.

  The dynamic damper in the fourth embodiment is the same as the dynamic damper 1 in the first embodiment except that the shape of the inner peripheral surface 81 of the mass body 80 is different. FIG. 3B is a side view of the mass body 80 in the fourth embodiment. In FIG. 3B, the outline of the overhang portion 53 is shown by a two-dot chain line.

  As shown in FIG. 3B, the inner peripheral surface 81 of the mass body 80 of the dynamic damper in the fourth embodiment is formed in a hexagonal shape extending in the second direction B when viewed in the axial direction. The inner peripheral surface 81 has a pair of first opposing surfaces 82 facing each other in the first direction A with the axis C (tubular member 10) interposed therebetween, and a pair of first opposing surfaces 82 in the second direction B with the axis C interposed therebetween. A pair of opposing second opposing surfaces 83 is provided. The first facing surface 82 is one side of a hexagon. The second facing surface 83 is two adjacent hexagonal sides.

  The distance L8 in the second direction B between the pair of second facing surfaces 63 is larger than the distance L7 in the first direction A between the pair of first facing surfaces 82. The interval L7 is constant over the entire length in the second direction B. The interval L7 is smaller than the outer diameter R1 of the overhang portion 53. Therefore, when viewed in the axial direction, a part of the protruding portion 53 is formed outside the pair of first opposing surfaces 82 in the direction perpendicular to the axis at any position where the mass body 80 is relatively rotated around the axis C with respect to the cylindrical member 10. Is located.

  Thereby, similarly to 1st Embodiment, it can prevent that the mass body 80 falls from the cylinder member 10 by the fracture | rupture of the elastic connection part 40, etc. FIG. Furthermore, since the distance L8 between the pair of second facing surfaces 83 can be set relatively freely regardless of the distance L7 between the pair of first facing surfaces 82 set according to the size and shape of the overhang portion 53, the mass The degree of freedom in setting the natural frequency of the dynamic damper having the body 80 can be improved.

  The interval in the first direction A of the inner peripheral surface 81 gradually decreases as the distance from the first facing surface 82 (position of the interval L7) in the second direction B increases when viewed in the axial direction. Further, the distance L7 between the pair of first opposing surfaces 82 is constant over the entire length in the second direction B. Further, in any cross section including the axial center C, the outline of the inner peripheral surface 81 and the axial center C are parallel over the entire length in the axial direction. In these cases, as described in the first embodiment, the mass body 80 can be easily formed and the dynamic damper having the mass body 80 can be formed as compared with the case where unevenness is provided on a part of the inner peripheral surface 81. It is easy to set the natural frequency.

  Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be easily made without departing from the spirit of the present invention. It is. For example, the shapes of the cylindrical member 10, the elastic coupling portion 40, the fastening member 50, and the like are examples, and it is natural to adopt various shapes. A tick that is dented in the axial direction from the axial end surface to the elastic connecting portion 40 between the outer peripheral surface 13 of the cylindrical member 10 and the inner peripheral surfaces 21, 61, 71, 81 of the mass bodies 20, 60, 70, 80. It may be provided.

  In addition, when viewed from the axial direction, the pair of first facing surfaces facing the first direction A among the inner circumferential surfaces of the mass body at any position where the mass body is relatively rotated around the axis C with respect to the cylindrical member 10. As long as a part of the overhanging part is located outside the direction perpendicular to the axis, the outer peripheral shape of the mass body and the overhanging part may be appropriately changed. In addition, while satisfying the relationship between the pair of first opposed surfaces and the overhanging portion as described above, the first opposed surface is opposed to the first direction A across the axis C (tubular member 10), and the first If the second facing surface faces the two directions B, the boundary between the first facing surface and the second facing surface may be set as appropriate. Further, the first facing surface and the second facing surface may not be continuous in the circumferential direction.

  In the first embodiment, the case where the flange of the flange bolt 51 is the overhang portion 53 has been described, but the present invention is not necessarily limited thereto. For example, a flange may be provided at the first end portion 11 of the cylindrical member, and a flange that is a part of the cylindrical member may be used as the overhang portion. Further, the head of a bolt (a part of the fastening member 50) that contacts the first end portion 11 of the tubular member 10 is used as an overhang portion, or a washer provided between the bolt and the first end portion 11 is stretched. It may be used as an exit.

  In each of the above-described embodiments, in any cross section including the axis C, the outline and the axis of the inner peripheral surfaces 21, 61, 71, 81 of the mass bodies 20, 60, 70, 80 extend over the entire length in the axial direction. Although the case where C is parallel is described, the present invention is not necessarily limited thereto. In the cross section including the axis C, the outline of the inner peripheral surface of the mass body may be inclined with respect to the axis C, or the outline may be provided with irregularities.

DESCRIPTION OF SYMBOLS 1 Dynamic damper 2 Opposite member 10 Cylinder member 11 1st end part 12 2nd end part 13 Outer peripheral surface 20, 60, 70, 80 Mass body 21, 61, 71, 81 Inner peripheral surface 22, 62, 72, 82 1st 1 opposing surface 23,63,73,83 2nd opposing surface 40 elastic connection part 50 fastening member 53,74 overhang | projection part A 1st direction B 2nd direction C axial center

Claims (4)

A cylindrical member having a first end and a second end in the axial direction;
A projecting portion projecting outward in the direction perpendicular to the axis of the cylindrical member at the first end;
A cylindrical mass disposed on the second end side of the projecting portion, with an inner circumferential surface disposed at a predetermined interval from the outer circumferential surface of the tubular member;
An elastic connecting portion composed of a rubber-like elastic body connecting the inner peripheral surface of the mass body and the outer peripheral surface of the cylindrical member;
A fastening member that is inserted into the tubular member and fastens the second end of the tubular member to the counterpart member;
The inner peripheral surface of the mass body includes a pair of first opposing surfaces that face each other in the first direction with the axis of the cylindrical member interposed therebetween,
A pair of second opposing surfaces sandwiching the axis therebetween and opposing each other in a second direction orthogonal to the first direction,
The distance between the pair of second facing surfaces in the second direction is larger than the distance between the pair of first facing surfaces in the first direction,
As seen in the axial direction of the cylindrical member, the protrusion extends outwardly in the direction perpendicular to the axis of the pair of first opposing surfaces at any position where the mass body is rotated relative to the cylindrical member around the axial center. Dynamic damper characterized in that a part of the part is located.   2. The dynamic damper according to claim 1, wherein, in any cross section including the axis, the outline of the inner peripheral surface of the mass body and the axis are parallel over the entire length in the axial direction.   The interval in the first direction of the inner peripheral surface of the mass body gradually decreases as it moves away from the position of the maximum interval in the first direction of the pair of first opposing surfaces in the second direction when viewed in the axial direction. The dynamic damper according to claim 1, wherein: 4. The dynamic damper according to claim 1, wherein a distance between the pair of first opposing surfaces in the first direction is constant over an entire length in the second direction. 5.

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