JPS631076Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a torsional damper that prevents torsional vibration of a crankshaft in an internal combustion engine, and is primarily suitable for use in motorcycles.

Due to its structure, it has a relatively long crankshaft, allowing for rapid acceleration,
In internal combustion engines (for example, motorcycle engines) that use a wide range of rotational speeds due to rapid deceleration, etc., torsional vibrations are likely to occur on the crankshaft, and a torsional damper is installed to alleviate the torsional vibrations.

FIG. 1 is a partial vertical side view showing a conventional torsional damper. A hub 3 is fixed to the end of a crankshaft 1 of an internal combustion engine by a nut 2.
An annular weight 7 is elastically connected to an annular plate 5 fixed to an outward flange 3 a of the hub 3 and forming a weight support member 4 together with the hub 3 via a rubber damper 6 . Also, as shown by the two-dot chain line, the one-way clutch 2 for the normal starter
0 is placed on the right side of the torsional damper.

In the conventional torsional damper configured in this manner, when torsional vibration occurs in the crankshaft 1, a relative displacement occurs between the hub 3 and the weight 7 in the rotational direction. As a result, the rubber damper 6 is twisted, and the vibration of the crankshaft 1 is absorbed and damped by the internal friction of the damper 6.

However, in the above configuration, if there is even a slight imbalance in the weight 7, the centrifugal force generated during rotation will be biased, and the weight 7 will become eccentric during rotation. Once eccentric, the centrifugal force will be further biased due to the eccentricity, and the eccentricity of the weight 7 will become even greater, and there is a risk that the rubber damper 6 may be damaged in some cases. Therefore, the spring constant of the rubber damper 6 cannot be set too low, and thin rubber must be used.
It was difficult to obtain a sufficient vibration damping effect.

Furthermore, a mounting structure for attaching a torsional damper to the end of the crankshaft on which a generator is mounted is shown in JP-A No. 56-3337, but that structure is not designed to prevent eccentricity of the weight. However, there are problems similar to those of the conventional example shown in FIG.

In view of the above problems, the present invention aims to provide a torsional damper that prevents the eccentricity of the weight during rotation and that can easily use a rubber damper that has sufficient elasticity to damp the vibrations of the crankshaft. It is characterized in that the annular weight is rotatably slidable and concentrically supported by a guide section provided on the weight support member.

FIG. 2 is a partial vertical sectional side view of the torsional damper according to the present invention. A tapered surface 9 is provided on the outer periphery of the end of a crankshaft 8 of an internal combustion engine, and a male threaded portion 10 is provided at the tip. A hub 11 having a corresponding inner peripheral surface is fitted into the tapered surface 9.
The hub 11 is fixed to the crankshaft 8 by passing the male threaded portion 10 through a hole 12 provided at the left end of the hub 11, and by screwing a nut 13 into the male threaded portion 10 from the left. The hub 11 has an outward flange 11a, and an annular plate 15 is fixed by bolts 16 to the outer periphery of the right end surface of the flange 11a. The annular plate 15 and the hub 11 constitute a weight support member 14 . One end surface of an annular rubber damper 17 is fixed to the outer periphery of the end surface of the plate 15 on the hub 11 side by baking or the like, and the rubber damper 17 is parallel to the plate 15.
An annular weight 18 is fixed to the other end surface by baking or the like, and the plate 15 and the weight 18 are elastically connected via a rubber damper 17. Furthermore, the inner circumferential surface 18a of the weight 18 is fitted into the guide portion (outer circumferential surface) 11b of the outward flange 11a, and is slidably supported. Due to this fitting, the weight 18 is always held concentrically with the hub 11.

Next, the operation will be explained. The crankshaft 8 begins to rotate when the internal combustion engine starts, and the rotation of the crankshaft 8 changes in various ways due to sudden acceleration, sudden deceleration, etc. When torsional vibration occurs in the crankshaft 8, the rotation of the hub 11 immediately changes according to the change in the rotation of the crankshaft 8, but the weight 18, which is elastically connected by the rubber damper 17, continues to rotate according to its own inertia force. Therefore, a relative rotational deviation occurs between the hub 11 and the weight 18. This deviation causes the rubber damper 17 to twist, and the vibration generated therein is absorbed and damped by the internal friction of the rubber damper 17.

At this time, the weight 18 always maintains concentricity with the hub 11 because the inner peripheral surface 18a is supported by the guide portion 11b of the flange 11a. Therefore, the weight 18 will not become eccentric. Furthermore, even if a rubber damper 17 with a low spring constant is used, there is no risk that the weight 18 will become eccentric.

As explained above, according to the present invention, the annular weight 18 is supported concentrically and slidably in the rotational direction by the guide portion 11b provided on the weight support member 14, so that eccentricity of the weight 18 during rotation can be completely prevented. There is no risk that the rubber damper 17 will be damaged due to eccentricity or that vibrations will occur due to eccentricity. Moreover, since the rubber damper 17 can be freely selected from a rubber damper with a low spring constant or a material with sufficient thickness, the rubber damper 1 has the optimum characteristics for damping the vibrations of the crankshaft 8.
7 can be easily adopted.

As shown in FIG. 3, as a guide portion that supports the weight 18 concentrically, a guide portion 15a that protrudes toward the weight 18 side and supports the outer peripheral surface of the weight 18 is integrally provided on the outer peripheral portion of the plate 15. You can. Also, in Figures 2 and 3, hub 1
1 by fixing the plate 15 to the weight support member 1.
4 is formed, however, the flange 11a of the hub 11 may be processed and deformed to replace the plate 15.

[Brief explanation of drawings]

FIG. 1 is a partial vertical side view of a conventional torsional damper, FIG. 2 is a partial vertical side view of a torsional damper according to the present invention, and FIG. 3 is a partial vertical side view of another embodiment. 8... Crankshaft, 11b, 15a... Guide portion, 14... Weight support member, 17... Rubber damper, 18... Annular weight.

Claims (1)

[Scope of utility model registration request] In a torsional damper in which a weight support member is fixed to the crankshaft and an annular weight is elastically connected to the outer circumference of the weight support member via a rubber damper, the annular weight is rotated by a guide section provided on the weight support member. A torsional damper characterized by being able to freely slide in any direction and being supported concentrically.