Dynamic damper, dynamic damper press-fitting method, and power transmission mechanism

Abstract

To smoothly press-fit a dynamic damper onto a shaft while ensuring good functions of the shaft and the dynamic damper. [Solution] A dynamic damper (40) comprising a cylindrical elastic member (41) attached to the outer peripheral surface of the shaft of a power transmission mechanism and a weight member (42) provided on the elastic member (41), wherein the inner peripheral surface of the elastic member (41) has a tapered surface (43) that expands toward at least one end in the axial direction.

Description

[Technical Field]

[0001] The present invention relates to a dynamic damper that is press-fitted onto the outer peripheral surface of a shaft of a power transmission mechanism, a method for press-fitting a dynamic damper, and a power transmission mechanism equipped with a dynamic damper. [Background technology]

[0002] In power transmission mechanisms such as drive shafts mounted on automobiles, vibrations can resonate and cause vibration amplification. To ensure the ride comfort and quietness required of automobiles, it is necessary to reduce resonant vibrations. As a method for reducing resonant vibrations, a method has been proposed in which a dynamic damper is attached to the drive shaft to adjust the natural frequency.

[0003] For example, Patent Document 1 (JP 2018-84307 A) discloses a dynamic damper having a cylindrical elastic member attached to the outer peripheral surface of a shaft and a weight member provided on the elastic member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-84307 Summary of the Invention [Problem to be solved by the invention]

[0005] Because the dynamic damper is press-fitted onto the outer surface of the shaft with an appropriate amount of interference, in the past, to ensure smooth press-fitting of the dynamic damper, a lubricant such as soapy water or rust-preventive oil was applied to the inner surface of the dynamic damper or the outer surface of the shaft before press-fitting.

[0006] However, applying soapy water leaves behind soapy water between the inner circumferential surface of the dynamic damper and the outer circumferential surface of the shaft, which can cause rust on the outer circumferential surface of the shaft. Applying anti-rust oil also leaves behind the risk of the natural rubber or other materials that make up the elastic member of the dynamic damper swelling due to the anti-rust oil, which can reduce the strength of the material or change the frequency characteristics.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to enable a dynamic damper to be smoothly press-fitted onto a shaft while ensuring good functionality of the shaft and dynamic damper. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a dynamic damper comprising a cylindrical elastic member attached to the outer peripheral surface of a shaft of a power transmission mechanism and a weight member provided on the elastic member, wherein the inner peripheral surface of the elastic member has a tapered surface that expands toward at least one end in the axial direction.

[0009] A dynamic damper with this configuration can be smoothly press-fitted into the shaft from the tapered surface side. Furthermore, since the dynamic damper can be smoothly press-fitted without using soapy water or anti-rust oil, it is possible to avoid rust on the shaft caused by soapy water, and a decrease in the physical strength and changes in frequency characteristics of the dynamic damper caused by anti-rust oil. Therefore, according to the present invention, it is possible to improve the workability of press-fitting the dynamic damper while ensuring good functionality of the shaft and dynamic damper.

[0010] The material of the elastic member may be a material containing a rubber component and a wax component.

[0011] In this case, the wax component contained in the elastic member increases the lubricity, further improving the ease of press-fitting the dynamic damper.

[0012] A groove into which the fixing band is attached may be provided on the outer peripheral surface of the portion having the tapered surface. In this case, it is preferable that the radial thickness of the portion in which the groove is provided is the same throughout the axial direction.

[0013] In this way, by making the radial thickness of the portion where the groove is provided the same thickness along the axial direction, the tightening force of the fixing band can be generated evenly, and the desired tightening force can be obtained.

[0014] Furthermore, in order to solve the above problems, the present invention proposes a method for press-fitting a dynamic damper, which includes a cylindrical elastic member attached to the outer surface of a shaft of a power transmission mechanism and a weight member provided on the elastic member, into the shaft, in which the dynamic damper is press-fitted into the shaft while at least one of the dynamic damper and the shaft is heated.

[0015] In this way, by heating at least one of the dynamic damper and the shaft before press-fitting, the elastic member of the dynamic damper is softened by the heat and becomes more susceptible to elastic deformation, allowing the dynamic damper to be smoothly press-fitted. Furthermore, this method allows the dynamic damper to be smoothly press-fitted without using soapy water or rust-preventive oil, thereby avoiding the occurrence of rust on the shaft due to soapy water and the reduction in the physical strength and changes in frequency characteristics of the dynamic damper due to rust-preventive oil, thereby improving the ease of press-fitting the dynamic damper while ensuring good functionality of the shaft and dynamic damper.

[0016] As another press-fitting method, we propose a method in which the dynamic damper is press-fitted onto the shaft with silicone oil applied to at least one of the inner peripheral surface of the dynamic damper and the outer peripheral surface of the shaft.

[0017] Silicone oil is a lubricant that does not cause rust, unlike soapy water, even when it adheres to the shaft, and is less likely to cause a decrease in physical strength or a change in frequency characteristics than rust-preventive oil. Therefore, by applying silicone oil to at least one of the inner circumferential surface of the dynamic damper and the outer circumferential surface of the shaft before press-fitting, and then press-fitting the dynamic damper onto the shaft with the silicone oil applied, the dynamic damper can be smoothly press-fitted while maintaining good functionality of the shaft and dynamic damper.

[0018] The above-mentioned press-fitting method using heat and the press-fitting method using silicone oil can also be applied to a dynamic damper having a tapered surface as described above.

[0019] The dynamic damper according to the present invention may also be applied to a power transmission mechanism including a shaft and two constant velocity universal joints connected to one end and the other end of the shaft so as to be able to transmit torque. This allows the dynamic damper to be smoothly press-fitted without the need for soapy water or rust-preventive oil, thereby providing a power transmission mechanism that is easy to press-fit while ensuring good functionality of the shaft and dynamic damper. [Effects of the Invention]

[0020] According to the present invention, the dynamic damper can be smoothly press-fitted onto the shaft while ensuring good functionality of the shaft and dynamic damper. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic configuration diagram of a drive shaft according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view of a drive shaft according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view of a dynamic damper according to an embodiment of the present invention. [Figure 4] 10A to 10C are diagrams for explaining a method of press-fitting a dynamic damper according to an embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing a modified example of the dynamic damper according to the present invention. [Figure 6] FIG. 10 is a cross-sectional view showing another modified example of the dynamic damper according to the present invention. [Figure 7] FIG. 10 is a cross-sectional view showing a modified example of a tapered surface. [Figure 8] FIG. 1 is a cross-sectional view of a dynamic damper that does not have a tapered surface. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described using a drive shaft as an example of a power transmission mechanism mounted on an automobile. In each drawing used to explain the embodiment of the present invention, components such as members and components having the same function or shape are designated by the same reference numerals as far as possible for distinction, and once they have been described, their description will be omitted.

[0023] FIG. 1 is a schematic diagram of a drive shaft according to an embodiment of the present invention.

[0024] The automobile 100 shown in Fig. 1 is equipped with a pair of drive shafts 90 as a power transmission mechanism that transmits the rotational torque of an engine E, which is a drive source, to left and right front wheels (wheels W), which are drive wheels. The pair of drive shafts 90 mainly includes a shaft 8 as a power transmission shaft, a fixed constant velocity universal joint 30 attached to the end of the shaft 8 on the outboard side (the outer side in the vehicle width direction or the wheel side), and a sliding constant velocity universal joint 1 attached to the inboard side (the inner side in the vehicle width direction or the differential side). The rotational torque of the engine E is shifted by a transmission T, and then distributed by a differential D to the left and right drive shafts 90 and transmitted to each wheel W.

[0025] FIG. 2 is a cross-sectional view of a drive shaft according to an embodiment of the present invention.

[0026] The configuration of each component included in the drive shaft 90 will be described below with reference to Figure 2. In the following description, unless otherwise specified, the term "axial direction" refers to the direction of the rotation axis of the drive shaft 90 or any axis parallel to the rotation axis, the term "circumferential direction" refers to the circumferential direction of a circle centered on the rotation axis of the drive shaft 90, and the term "radial direction" refers to a direction intersecting the rotation axis of the drive shaft 90 (including a direction perpendicular to the rotation axis).

[0027] The fixed type constant velocity universal joint 30 according to the embodiment of the present invention is a so-called Birfield type constant velocity universal joint, and includes an outer joint member 15, an inner joint member 18, balls 19, and a cage 20 as its main components.

[0028] The outer joint member 15 has a plurality of track grooves 13 extending in the axial direction on an inner peripheral surface 14. On the other hand, the inner joint member 18 has a plurality of track grooves 16 extending in the axial direction on an outer peripheral surface 17. The track grooves 13 of the outer joint member 15 and the track grooves 16 of the inner joint member 18 are both provided at equal intervals in the circumferential direction and are arranged to face each other. Furthermore, one ball 19 serving as a torque transmission member is housed between each of the facing track grooves 13, 16 of the outer joint member 15 and the inner joint member 18. The ball 19 is rotatably held by a cage 20 interposed between the outer joint member 15 and the inner joint member 18. As each ball 19 rolls along the track grooves 13, 16, the inner joint member 18 can transmit rotational torque while allowing angular displacement with respect to the outer joint member 15.

[0029] The sliding type constant velocity universal joint 1 according to the embodiment of the present invention is a so-called tripod type constant velocity universal joint, and includes an outer joint member 22, a tripod member 24, and a roller unit 25 as main components.

[0030] The outer joint member 22 has three track grooves 21 extending in the axial direction on its inner circumferential surface. The track grooves 21 are provided with roller guideways 21a facing each other. The tripod member 24 has three trunnions 23 protruding in the radial direction. A roller unit 25 is attached to each trunnion 23. The roller unit 25 is composed of an outer ring 26 which is a roller, an inner ring 27 which is disposed inside the outer ring 26 and fitted onto the trunnion 23, and needle rollers 28 which are interposed between the outer ring 26 and the inner ring 27. One roller unit 25 is disposed in each track groove 21 of the outer joint member 22, and the outer ring 26 moves along the track grooves 21, allowing the tripod member 24 to transmit rotational torque to the outer joint member 22 while allowing angular and axial displacement therebetween.

[0031] The shaft 8 according to the embodiment of the present invention has male splines 8a, 8b formed at both ends thereof. Meanwhile, a female spline 34 that fits with one of the male splines 8a of the shaft 8 is formed in the axial hole 33 of the inner joint member 18 of the fixed type constant velocity universal joint 30. One of the male splines 8a of the shaft 8 is fitted into the axial hole 33 of the inner joint member 18 and fitted with the female spline 34, thereby connecting one end of the shaft 8 to the fixed type constant velocity universal joint 30. Furthermore, a female spline 36 that fits with the other male spline 8b of the shaft 8 is formed in the axial hole 35 of the boss portion 29 of the tripod member 24. The other male spline 8b of the shaft 8 is fitted into the axial hole 35 of the boss portion 29 of the tripod member 24 and fitted with the female spline 36, thereby connecting the other end of the shaft 8 to the sliding type constant velocity universal joint 1.

[0032] Boots 37A, 37B for sealing the openings of the fixed type constant velocity universal joint 30 and the sliding type constant velocity universal joint 1 are attached, respectively. Each boot 37A, 37B is composed of a large diameter end 37a, a small diameter end 37b, and a bellows portion 37c connecting the large diameter end 37a and the small diameter end 37b. The large diameter end 37a of the boots 37A, 37B is fastened and fixed by fixing bands 38A, 38B to the outer peripheral surfaces of the opening sides of the outer joint members 15, 22 of the fixed type constant velocity universal joint 30 and the sliding type constant velocity universal joint 1. Meanwhile, the small diameter end 37b of the boots 37A, 37B is fastened and fixed by fixing bands 39A, 39B to the outer peripheral surface of a predetermined portion of the shaft 8.

[0033] A dynamic damper 40 is attached to the middle portion of the shaft 8. The dynamic damper 40 includes a cylindrical elastic member 41 attached to the outer circumferential surface of the shaft 8, and a weight member 42 attached to the elastic member 41. The elastic member 41 has a main body 41a that houses the weight member 42, and a pair of mounting portions 41b that are provided on both axial ends of the main body 41a. The main body 41a and the pair of mounting portions 41b are integrally molded products made of an elastic member such as natural rubber.

[0034] The pair of mounting portions 41b are press-fitted onto the outer peripheral surface of the shaft 8. For this reason, the inner peripheral surface of each mounting portion 41b is formed with an inner diameter smaller than the outer diameter of the shaft 8 (the outer diameter of the portion where the mounting portion 41b is mounted) so as to have a predetermined interference with the outer peripheral surface of the shaft 8. In contrast, the main body portion 41a has an inner peripheral surface with an inner diameter larger than the outer diameter of the shaft 8 (the outer diameter of the portion where the main body portion 41a is disposed). Therefore, when the dynamic damper 40 is mounted on the shaft 8, an annular gap is formed between the inner peripheral surface of the main body portion 41a and the outer peripheral surface of the shaft 8.

[0035] Furthermore, an annular groove 41c is provided on the outer peripheral surface of one of the pair of mounting portions 41b, into which a fixing band 50 serving as a fastening member is attached. The fixing band 50 is attached to this groove 41c, and one of the mounting portions 41b is fastened by the fixing band 50, thereby fixing the dynamic damper 40 to the shaft 8. Alternatively, grooves 41c may be provided on the outer peripheral surfaces of both mounting portions 41b, and both mounting portions 41b may be fastened by the fixing bands 50.

[0036] The weight member 42 is a cylindrical member made of a metal material or the like. The weight member 42 is integrally molded with the elastic member 41 by, for example, insert molding. The material of the weight member 42 may be metal, or may be a material other than metal as long as it has a sufficiently higher specific gravity than the material of the elastic member 41.

[0037] The natural frequency (frequency characteristics) of the dynamic damper 40 is determined by the mass of the weight member 42 and the elastic coefficient of the elastic member 61. The vibration amplification phenomenon can be suppressed by adjusting the natural frequency of the dynamic damper 40 so that it resonates with a frequency that is a main cause of the vibration amplification phenomenon. For example, even if bending vibrations or torsional vibrations of the shaft 8 occur due to unbalanced rotation of the shaft 8 while the vehicle is running, the natural frequency of the dynamic damper 40 is adjusted to resonate with the frequency that is a main cause of the vibration amplification phenomenon. Therefore, the vibration energy of the shaft 8 is converted into vibration energy of the dynamic damper 40 and absorbed. This reduces the vibration of the shaft 8 and suppresses the vibration amplification phenomenon.

[0038] Since the dynamic damper is press-fitted onto the outer surface of the shaft with an appropriate amount of interference, in the past, in order to ensure smooth press-fitting of the dynamic damper, a lubricant such as soapy water or rust-preventive oil was applied to the inner surface of the dynamic damper or the outer surface of the shaft before press-fitting.

[0039] However, applying soapy water carries the risk of rust forming on the outer surface of the shaft, and applying anti-rust oil carries the risk of the elastic material of the dynamic damper swelling due to the anti-rust oil, resulting in a decrease in physical strength and changes in the natural vibration characteristics.

[0040] Therefore, the present invention proposes a dynamic damper configuration and a press-fitting method that can be smoothly press-fitted without using soapy water or anti-rust oil. The configuration and press-fitting method of a dynamic damper according to an embodiment of the present invention will be described below.

[0041] <Configuration of a dynamic damper with a tapered surface and press-fitting method> FIG. 3 is a cross-sectional view of a dynamic damper according to an embodiment of the present invention.

[0042] 3, in the dynamic damper 40 according to the embodiment of the present invention, a tapered surface 43 that widens toward one axial end (the left end in FIG. 3) of the dynamic damper 40 is provided on the inner circumferential surface of the elastic member 41. More specifically, the tapered surface 43 is provided on the inner circumferential surface of one of the pair of mounting portions 41b (the left side in FIG. 3), and widens toward the side opposite the main body portion 41a at a predetermined inclination angle θ with respect to the center line O of the dynamic damper 40.

[0043] In this case, the inner circumferential surface of the other mounting portion 41b (on the right side in FIG. 3) and the inner circumferential surface of the main body portion 41a are formed by cylindrical surfaces 44, 45 parallel to the center line O of the dynamic damper 40. Also, on the inner circumferential surface between each mounting portion 41b and the main body portion 41a, reverse tapered surfaces 46, 47 that narrow toward both axial ends of the dynamic damper 40 are provided, opposite the tapered surface 43, and the tapered surface 43 is provided so as to widen from the side of the reverse tapered surface 46 on one side (on the left side in FIG. 3) toward one axial end.

[0044] The inclination angle θ of the tapered surface 43 with respect to the center line O is set to, for example, 1° or more and 5° or less. The axial length of the tapered surface 43 is preferably 50% or more of the region from the inner diameter portion in the axial direction.

[0045] As described above, in the embodiment of the present invention, the inner circumferential surface of one mounting portion 41b of the dynamic damper 40 is provided with a tapered surface 43 that widens toward one axial end. Therefore, as shown in FIG. 4 , the dynamic damper 40 can be smoothly press-fitted into the shaft 8 by press-fitting it from the tapered surface 43 side. That is, when the tip of the shaft 8 enters the dynamic damper 40 from the tapered surface 43 side, the tip of the shaft 8 is guided along the tapered surface 43, reducing the resistance of the shaft 8 due to the interference of the dynamic damper 40. This allows the shaft 8 to be smoothly inserted (press-fitted). Furthermore, in the embodiment of the present invention, the dynamic damper can be smoothly press-fitted without using soapy water or rust-preventive oil. This avoids the occurrence of rust on the shaft due to soapy water, and the deterioration of the physical strength and change in frequency characteristics of the dynamic damper due to rust-preventive oil. Therefore, the present invention improves the ease of press-fitting the dynamic damper while maintaining the proper function of the shaft and dynamic damper.

[0046] Furthermore, a material containing a wax component in addition to the rubber component may be used as the material for the elastic member 41. In this case, the wax component contained in the elastic member 41 increases the lubricity, further improving the ease of press-fitting the dynamic damper 40.

[0047] In this embodiment of the present invention, the tapered surface 43 is provided on the mounting portion 41b to which the fixing band 50 is fastened. Therefore, if the bottom surface of the groove 41c were a cylindrical surface parallel to the center line O, the bottom surface of the groove 41c would be at a different angle from the tapered surface 43, and the radial thickness T (see FIG. 3) of the portion where the groove 41c is provided would vary along the axial direction. In this case, the fastening force of the fixing band 50 would vary between the thick and thin portions, making it difficult to obtain the desired fastening force. Therefore, in this embodiment of the present invention, the bottom surface (outer peripheral surface) of the groove 41c is made a tapered surface inclined at the same inclination angle θ as the tapered surface 43, so that the radial thickness T of the portion where the groove 41c is provided is made uniform along the axial direction. This allows the fastening force of the fixing band 50 to be generated evenly, thereby achieving the desired fastening force.

[0048] Furthermore, the tapered surface 43 is not limited to being provided on the mounting portion 41b having the recessed groove 41c. As shown in the example of FIG. 5, the tapered surface 43 may be provided on the inner circumferential surface of the mounting portion 41b that does not have the recessed groove 41c. Furthermore, as shown in the example of FIG. 6, the tapered surface 43 may be provided on the inner circumferential surfaces of both mounting portions 41b. In either case, by press-fitting the dynamic damper 40 onto the shaft 8 from the tapered surface 43 side, the dynamic damper 40 can be smoothly press-fitted, as in the above embodiment. In short, it is sufficient that the tapered surface 43 is provided so as to widen toward at least one axial end of the dynamic damper 40.

[0049] Furthermore, in the embodiment of the present invention, the cross section of the tapered surface 43 is formed so as to be linearly inclined with respect to the center line O of the dynamic damper 40 (see FIG. 3), but the cross section of the tapered surface 43 does not necessarily have to be a linear cross section. For example, as in the example of FIG. 7, the tapered surface 43 may be formed so as to have a cross section that is curvedly inclined with respect to the center line O. In this case, it is preferable that the bottom surface of the recessed groove 41c be formed so as to have a curved cross section with the same curvature as the tapered surface 43 so that the portion where the recessed groove 41c is provided has the same thickness along the axial direction.

[0050] Next, another press-fitting method according to the present invention will be described.

[0051] <Press-fitting method using heat> The elastic member of the dynamic damper is generally made of a material such as rubber, which loses hardness as the temperature rises. Therefore, when the dynamic damper is heated, the elastic member softens and becomes more susceptible to elastic deformation.

[0052] Therefore, focusing on this point, we propose a method of heating the dynamic damper before press-fitting it in. That is, the dynamic damper is heated using a heating device such as a heater before press-fitting, and the dynamic damper is press-fitted onto the shaft in its heated state.

[0053] When the dynamic damper is heated, the elastic member softens and becomes more elastically deformable, allowing the dynamic damper to be smoothly press-fitted without the need for soapy water or anti-rust oil. Therefore, the press-fitting method of the present invention can avoid rust on the shaft caused by soapy water and a decrease in the physical strength and changes in frequency characteristics of the dynamic damper caused by anti-rust oil, thereby improving the ease of press-fitting the dynamic damper while ensuring good functionality of the shaft and dynamic damper.

[0054] Alternatively, instead of heating the dynamic damper, the shaft may be heated. By press-fitting the dynamic damper onto a shaft that has already been heated, the heat of the shaft is transferred to the elastic member of the dynamic damper, and the inner circumferential surface of the elastic member is softened by the heat of the shaft. This allows the dynamic damper to be press-fitted smoothly. Alternatively, both the dynamic damper and the shaft may be heated before press-fitting.

[0055] As described above, the method of press-fitting a dynamic damper onto a shaft while at least one of the dynamic damper and the shaft is heated can be applied not only to a dynamic damper 40 having a tapered surface 43 as shown in FIG. 3, but also to a dynamic damper 40 without a tapered surface 43 as shown in FIG. 8. Even in the case of a dynamic damper 40 in which the inner circumferential surfaces of both mounting portions 41b are cylindrical surfaces 48, 49 parallel to the center line O as shown in FIG. 8, by press-fitting the dynamic damper onto the shaft while at least one of the dynamic damper and the shaft is heated, the dynamic damper can be smoothly press-fitted even without a tapered surface 43 on the inner circumferential surface. Note that a dynamic damper 40 with a tapered surface 43 can be press-fitted even more smoothly than a dynamic damper 40 without a tapered surface 43. In other words, by pressing the dynamic damper 40 into the shaft 8 from the tapered surface 43 side while at least one of the dynamic damper 40 and the shaft 8 is heated, the softening of the elastic member 41 due to the heat and the guiding function of the tapered surface 43 make it even easier to press the dynamic damper 40 into place.

[0056] <Press-fitting method using silicone oil> Next, we will explain the press-fitting method using silicone oil. Silicone oil is a lubricant that does not cause rust, unlike soapy water, even when it adheres to the shaft, and is less likely to reduce physical strength or change frequency characteristics compared to rust-preventive oils.

[0057] Therefore, by applying silicone oil to at least one of the inner surface of the dynamic damper and the outer surface of the shaft before pressing in, and then pressing the dynamic damper into the shaft with the silicone oil applied, the dynamic damper can be pressed in smoothly while maintaining good functionality of the shaft and dynamic damper.

[0058] Furthermore, this press-fitting method using silicone oil can be applied not only to a dynamic damper 40 having a tapered surface 43 as shown in Fig. 3, but also to a dynamic damper 40 not having a tapered surface 43 as shown in Fig. 8. In particular, in the case of a dynamic damper 40 having a tapered surface 43, by press-fitting the dynamic damper 40 into the shaft 8 from the tapered surface 43 side with silicone oil applied to at least one of the inner peripheral surface of the dynamic damper 40 and the outer peripheral surface of the shaft 8, press-fitting can be performed even more smoothly than in the case of a dynamic damper 40 not having a tapered surface 43.

[0059] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the gist of the invention.

[0060] In the above-described embodiment, a Birrfield type fixed constant velocity universal joint is used as an example of the fixed constant velocity universal joint provided on the drive shaft, but the fixed constant velocity universal joint may also be an undercut-free type fixed constant velocity universal joint. Furthermore, the sliding type constant velocity universal joint is not limited to a tripod type sliding type constant velocity universal joint, but may also be a double offset type or cross groove type sliding type constant velocity universal joint. Furthermore, the tripod type sliding type constant velocity universal joint may be a single roller type or a double roller type.

[0061] Furthermore, in the above-described embodiment, the present invention has been described using a drive shaft mounted on an automobile as an example, but the present invention is not limited to drive shafts and can also be applied to power transmission mechanisms used in various other industrial machines. [Explanation of symbols]

[0062] 1. Sliding constant velocity universal joint 8 shafts 30 Fixed constant velocity universal joint 40 Dynamic Damper 41 Elastic member 41c groove 42 Weight member 43 Tapered surface 50 fixed band 90 Drive shaft (power transmission mechanism)

Claims

1. A dynamic damper comprising: a cylindrical elastic member attached to an outer peripheral surface of a shaft of a power transmission mechanism; and a weight member provided on the elastic member, A dynamic damper characterized in that the inner peripheral surface of the elastic member has a tapered surface that widens toward at least one end in the axial direction.

2. 2. The dynamic damper according to claim 1, wherein the material of the elastic member contains a rubber component and a wax component.

3. a groove in which a fixing band is attached is provided on the outer peripheral surface of the portion having the tapered surface, 2. The dynamic damper according to claim 1, wherein the radial thickness of the portion where the recessed groove is provided is uniform throughout the axial direction.

4. 1. A press-fitting method for press-fitting a dynamic damper into a shaft of a power transmission mechanism, the dynamic damper including a cylindrical elastic member attached to an outer peripheral surface of the shaft and a weight member provided on the elastic member, the method comprising: A method for press-fitting a dynamic damper, comprising press-fitting the dynamic damper onto the shaft while at least one of the dynamic damper and the shaft is heated.

5. 1. A press-fitting method for press-fitting a dynamic damper into a shaft of a power transmission mechanism, the dynamic damper including a cylindrical elastic member attached to an outer peripheral surface of the shaft and a weight member provided on the elastic member, the method comprising: A method for press-fitting a dynamic damper, characterized in that the dynamic damper is press-fitted onto the shaft with silicone oil applied to at least one of the inner peripheral surface of the dynamic damper and the outer peripheral surface of the shaft.

6. 10. A method for press-fitting a dynamic damper according to claim 1 into a shaft of a power transmission mechanism, comprising: A method for press-fitting a dynamic damper, characterized in that the dynamic damper is press-fitted onto the shaft from the tapered surface side while at least one of the dynamic damper and the shaft is heated.

7. 10. A method for press-fitting a dynamic damper according to claim 1 into a shaft of a power transmission mechanism, comprising: A method for pressing a dynamic damper, characterized in that silicone oil is applied to at least one of the inner surface of the dynamic damper and the outer surface of the shaft, and the dynamic damper is pressed into the shaft from the tapered surface side.

8. a shaft to which the dynamic damper according to claim 1 is attached; and two constant velocity universal joints connected to one end and the other end of the shaft so as to be able to transmit torque.

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