JP5084410B2 - Dynamic damper for propeller shaft - Google Patents

Description

The present invention relates to a dynamic damper that is mounted in a hollow portion of a propeller shaft and suppresses a resonance phenomenon caused by rotation of the propeller shaft.

Conventionally, a hollow propeller shaft is used to transmit the power output from the transmission to the drive wheels. However, the engine vibration is transmitted to the propeller shaft, resonates with the propeller shaft, and generates noise and vibration called booming noise. cause. As a countermeasure against such resonance, various examples in which a dynamic damper 30 is mounted in the hollow portion of the propeller shaft 20 as shown in FIG. 6 have been proposed.

As shown in FIG. 7, the dynamic damper 30 described in Patent Document 1 includes a cylindrical outer pipe (outer cylinder member) 31, an inner weight (weight) 32 disposed on the axis of the outer pipe 31, and an outer pipe 31. And an inner weight 32 are provided with a mounting rubber (damping member) 33, and the outer pipe 31 is press-fitted into the propeller shaft 20. The outer diameter of the outer pipe 31 is set so as not to cause radial play or axial displacement in a state where it is press-fitted into the hollow portion of the propeller shaft. However, since the inner diameter of the propeller shaft 20 varies, it is difficult to stably press-fit the outer pipe 31 into the hollow portion of the propeller shaft 20 even if the outer diameter of the outer pipe 31 is controlled. In addition, since the thickness of a normal propeller shaft is as thin as about 1.6 mm, if the outer pipe 31 is forcibly press-fitted into the hollow portion of the propeller shaft, distortion of the propeller shaft increases and mechanical strength decreases. is there.

To compensate for this drawback, as shown in FIGS. 8A and 8B, the outer pipe 40 is formed with a plurality of bulging portions 41 bulging radially outward at intervals in the circumferential direction. There is a dynamic damper having a structure in which the bulging portion 41 is pressed against the inner wall of the hollow portion of the propeller shaft (Patent Document 2). In addition, 42 is an inner weight and 43 is a mount rubber. The bulging portion 41 bulges in a stepped manner from the vicinity of one end of the outer pipe 40 in the axial direction to the outer peripheral side, and extends in the axial direction to the other end of the outer pipe 40.

In this case, the variation in the inner diameter of the propeller shaft can be absorbed by the bulging portion 41 formed by dispersing in the circumferential direction, so that the stability of the press-fitting is increased as compared with the dynamic damper shown in FIG. However, when the outer pipe 40 is press-fitted from the side from which the bulging portion 41 protrudes (the other end side), there is a problem that a catch at the time of press-fitting occurs. Further, since the bulging portion 41 is formed over substantially the entire length of the outer pipe 40 in the axial direction, the axial contact length with the propeller shaft is long, the distortion increases, and the press-fit load increases.

Japanese Utility Model Publication No. 4-27238 JP-A-8-290722

Accordingly, an object of the present invention is to provide a dynamic damper for a propeller shaft that can eliminate the excessive distortion of the propeller shaft and can be stably attached to the propeller shaft.

In order to achieve the above object, the present invention includes a cylindrical outer pipe, an inner weight disposed at the axial center of the outer pipe, and a mount rubber that elastically connects the outer pipe and the inner weight. In the dynamic damper mounted in the hollow portion of the propeller shaft, the outer pipe has a cylindrical body portion having an outer diameter smaller than the inner diameter of the propeller shaft, and in the radial direction near both axial end portions of the body portion. a plurality of projections projecting outward are formed at intervals in the circumferential direction, the narrowed portion is narrowed in a tapered shape from the protrusions toward the axial tip of the outer pipe is formed, the narrowed portion is all It is continuous over the periphery, and the leading end outer diameter of the throttle portion is smaller than the outer diameter of the body portion, the outer diameter of the protrusion than the inner diameter of said propeller shaft Is listening set, said when pressed into the propeller shaft outer pipe, providing a propeller dynamic damper shaft, characterized in that the pressure in the hollow inner wall of the propeller shaft and the projection is deformed.

When the outer pipe has a simple cylindrical shape as in the conventional case, even if the outer diameter of the outer pipe is controlled, if the inner diameter of the propeller shaft varies, the outer pipe cannot be stably press-fitted into the propeller shaft. In the present invention, since a plurality of protrusions having outer diameters larger than the inner diameter of the propeller shaft are formed in the vicinity of both ends in the axial direction of the outer pipe at intervals in the circumferential direction, when the outer pipe is press-fitted into the propeller shaft, the protrusions Can be dispersed and pressed in the axial direction and the circumferential direction of the propeller shaft, and the outer pipe can be stably attached without causing excessive distortion in the propeller shaft. Since the narrowed portion is tapered from the protrusion toward the tip of the outer pipe in the axial direction, it is possible to prevent the outer pipe from being caught at the start of press-fitting of the outer pipe. In particular, since the throttle portions are formed at both ends in the axial direction of the outer pipe, the outer pipe has no directionality and can be press-fitted into the propeller shaft from any direction.

As a method of forming the protrusion, for example, a plurality of axial slits may be formed near both ends of the outer pipe, and the intermediate portion may be protruded into a mountain shape radially outward, or may be processed near both ends of the outer pipe. A portion having a diameter other than the window hole may be used as the protrusion by forming a continuously enlarged diameter portion in the circumferential direction and forming a plurality of window holes in the enlarged diameter portion.

As described above, according to the dynamic damper of the present invention, the plurality of protrusions are formed at both ends of the outer pipe at intervals in the circumferential direction, so that when the outer pipe is press-fitted into the propeller shaft, the axial direction and the circumference Strain is generated only in a part of the direction, so that excessive strain can be eliminated and the press-fit load can be reduced. Further, since the protrusion is formed in the vicinity of both end portions of the outer pipe, the inclination of the outer pipe can be prevented. Furthermore, since the narrowed portion is formed in a tapered shape from the protrusion toward the tip of the outer pipe in the axial direction, the outer pipe can be smoothly pressed into the propeller shaft from any direction.

Embodiments of the present invention will be described below with reference to examples.

FIG. 1 is a cross-sectional view of an example of a dynamic damper according to the present invention attached to a propeller shaft, FIG. 2 is a half cross-sectional view of the dynamic damper, and FIG. 3 is a perspective view.

As shown in FIGS. 1 to 3, the dynamic damper device 1 includes a cylindrical outer pipe 2 that is inserted into the hollow portion of the propeller shaft 10, and a columnar inner weight 3 that is disposed at the axial center of the outer pipe 2. , And a mounting rubber 4 that elastically connects the outer pipe 2 and the inner weight 3. The outer pipe 2 and the inner weight 3 are made of a high-strength metal material such as steel.

A cylindrical body 2a is formed at the axial center of the outer pipe 2, and a plurality of protrusions 2b projecting outward in the radial direction are spaced in the circumferential direction near both axial ends of the body 2a. It is formed with a gap. The protruding portion 2b of this embodiment is formed by forming a pair of slits in the axial direction and projecting the intermediate portion in a mountain shape outward in the radial direction, and both side surfaces in the axial direction are inclined in a tapered shape. At both ends in the axial direction of the outer pipe 2, tapered throttle portions 2 c that gradually reduce in diameter toward the tip in the axial direction are formed on the entire circumference. The tapered surface of the narrowed portion 2c is continuous with one tapered side surface of the protruding portion 2b. The outer diameter Da of the protrusion 2b is larger than the inner diameter Dp of the propeller shaft 10 as shown in the following equation, and is set so that the protrusion 2b can be deformed when the outer pipe 2 is press-fitted into the propeller shaft 10.
Dp <Da

The mount rubber 4 is vulcanized and bonded to the inner peripheral surface of the outer pipe 2 and the outer peripheral surface of the inner weight 3. The mount rubber 4 is formed with a plurality of cavities 4a penetrating in the axial direction. In this embodiment, four cavities 4a are formed at intervals of 90 °. The outer peripheral portion of the mount rubber 4 bonded to the inner peripheral surface of the outer pipe 2 terminates at a position entering the inner side in the axial direction from the inner peripheral surface of the protrusion 2b.

When the outer pipe 2 having the shape as described above is press-fitted into the propeller shaft 10, since the tapered throttle portions 2c are formed at both ends in the axial direction of the outer pipe 2, the outer pipe 2 can be smoothly press-fitted and the outer pipe 2 is pressed in the opposite direction. It can be press-fitted without any problem. In particular, since the tapered surface is continuous from the narrowed portion 2c to the protruding portion 2b, it is possible to prevent catching at the start of press-fitting and catching during press-fitting. When the outer pipe 2 is press-fitted, it is necessary to press the end face of the outer pipe 2 with a jig. However, as described above, since the narrowed portions 2c are formed at both axial ends of the outer pipe 2, the diameter in contact with the jig is small. It becomes smaller and the press-fitting work becomes stable.

Since the outer diameter Da of the protruding portion 2b is larger than the inner diameter Dp of the propeller shaft 10, when the outer pipe 2 is press-fitted, a part of the protruding portion 2b is pressed against the inner wall of the hollow portion of the propeller shaft 10 while being deformed. However, since the projecting portion 2b is formed only in a part of the outer pipe 2 in the axial direction and the circumferential direction, the propeller shaft 10 is also partially distorted to prevent excessive distortion and to reduce the press-fit load. it can. In general, the propeller shaft 10 is formed by bending a flat plate into a cylindrical shape and welding the mating portion, but the weld trace of the mating portion remains in a bead shape on the inner peripheral surface. In the present embodiment, since the protrusions 2b are formed at intervals in the circumferential direction, press fitting can be performed while avoiding welding marks formed on the inner surface of the propeller shaft 10.

4 and 5 show a second embodiment of the dynamic damper according to the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the dynamic damper 1A of this embodiment, a radially enlarged portion 2d having a mountain-shaped cross section that is continuous in the circumferential direction is formed in the vicinity of both axial end portions of the outer pipe 2, and a plurality of window holes 2e are circumferentially spaced in the enlarged diameter portion 2d. By forming the gap, the enlarged diameter portion other than the window hole is used as the protrusion. On the shaft end side of the enlarged diameter portion 2d, a tapered throttle portion 2f that is gradually reduced in diameter toward the tip is formed. Also in this embodiment, the enlarged diameter portion 2d is set to be in pressure contact with the hollow portion inner wall of the propeller shaft 10 by making the outer diameter Da of the enlarged diameter portion 2d larger than the inner diameter of the propeller shaft 10.

Similarly to the first embodiment, the dynamic damper of this embodiment is also formed with tapered throttle portions 2f at both axial ends of the outer pipe 2, so that it is possible to prevent catching at the start of press-fitting or during press-fitting. Further, since the protruding portion (expanded diameter portion 2d) is only formed in a part of the outer pipe 2 in the axial direction and the circumferential direction, it does not cause excessive distortion in the propeller shaft and can reduce the press-fit load. There is an advantage that press-fit workability is improved.

It is sectional drawing of the state with which the 1st Example of the dynamic damper concerning this invention was mounted | worn with the propeller shaft. FIG. 2 is a half sectional view of the dynamic damper shown in FIG. 1. It is a perspective view of the dynamic damper shown in FIG. It is a half sectional view of the 2nd example of the dynamic damper concerning the present invention. It is a perspective view of the dynamic damper shown in FIG. It is the side view which fractured | ruptured a part of propeller shaft with which the conventional dynamic damper was mounted | worn. It is sectional drawing of an example of the conventional dynamic damper. It is sectional drawing and the side view of the other example of the conventional dynamic damper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Dynamic damper 2 Outer pipe 2a Body part 2b Projection part 2c Restriction part 2d Expanded diameter part 2e Window hole 2f Restriction part 3 Inner weight 4 Mount rubber 10 Propeller shaft

Claims (1)

A dynamic outer cylinder having a cylindrical outer pipe, an inner weight disposed at the axial center of the outer pipe, and a mount rubber for elastically connecting the outer pipe and the inner weight, and mounted in a hollow portion of the propeller shaft In the damper,
The outer pipe has a cylindrical body having an outer diameter smaller than the inner diameter of the propeller shaft,
A plurality of protrusions protruding outward in the radial direction are formed at intervals in the circumferential direction in the vicinity of both axial ends of the body portion ,
A constricted portion that is constricted in a tapered shape is formed from the protruding portion toward the distal end in the axial direction of the outer pipe,
The throttle part is continuous over the entire circumference, and the outer diameter of the tip part of the throttle part is smaller than the outer diameter of the body part,
The outer diameter of the projecting portion is set larger than the inner diameter of the propeller shaft, and when the outer pipe is press-fitted into the propeller shaft, the projecting portion is deformed and press-contacted to the inner wall of the hollow portion of the propeller shaft. Dynamic damper.

Images