Clutch for a Motorcycle

Field of the invention

The present invention relates to "Clutch for a motorcycle" and more particularly to noise reduction in centrifugal clutch of a motorcycle.

Description of the prior art

A centrifugal clutch works through centrifugal force. The said centrifugal clutch assembly comprises of a carrier plate welded with a hub and a pair of pivot pins attached to the carrier plate away from the centre of the hub. A pair of clutch shoes are pivotally mounted on the pivot pins and prevented from coming out of the pivot pins by a pair of circlips assembled on the pivot pin. The shoes are provided with a pair of hooking holes or openings and a pair of springs are mounted between the shoes. Clutch shoes are placed in such way that side opposite to pivot point of any shoe is closer to pivot point of the other shoe. A primary damper is placed at the end of each said clutch shoe opposite to the pivot point. Primary dampers are used to avoid jerks and rubbing of the clutch shoes during the working of the clutch. Shoes are provided with its outer diameter being attached with a friction lining material. The clutch is connected to the engine crankshaft that in turn drives a shaft, chain or belt. As the engine RPM increases, weighted shoes in the clutch swing outwards and force the clutch to engage to a clutch drum that is mounted on a crankshaft. As the load increases the rpm drops, disengaging the clutch, letting the rpm rise again and re-engaging the clutch to the clutch drum.

With continuous usage, wear and tear of the primary dampers shoe happens and starts deteriorating. As a result, noise is produced in the clutch assembly due to rubbing of the shoes.

Hence there is a need to provide a means for reducing the noise in the said centrifugal clutch assembly even after the primary dampers have withered due to continuous wear and tear.

Another objective of the present invention is to provide a means that increases the operational life of the clutch assembly.

Brief description of the invention

According to one of the embodiments of the present invention, a secondary damper preferably rubber is provided around the hub. This secondary damper rigidly holds the hub. A groove is made on the circumference of the hub which is aligned to a projection in the inside surface of the secondary damper, thus making the said damper to be fitted perfectly and tightly on to the hub. During the operation of the clutch shoes, the inner portion of the said clutch shoe rest on the above said damper, and as a result the noise produced due to the chattering of the shoes are reduced considerably even in the likely event of the failing of the primary damper.

Brief description of the drawings

Figure 1 illustrates side view of a motorcycle

Figure 2 illustrates a centrifugal clutch according to the prior art

Figure 3 illustrates a centrifugal clutch according to the present invention

Detailed description of the invention

A selected illustrative embodiment of the present invention will be now described with respect to the accompanying figures 1,2 and 3. A motorcycle comprises of a frame 101, front fork 102 attached to a pivot tube 103 of the vehicle frame 101, a front wheel 104 attached to these front forks 102, a handle bar 105 connected to the front forks 102, a fuel tank (not shown in the figure) attached so as to straddle an upper part of the vehicle frame 101, a seat 107 attached to the upper rear portion of the vehicle frame 101, an engine unit 108 attached to the lower front section of the vehicle frame 101, a swing arm 109 attached to a lower rear section of the vehicle frame 101, suspended by a rear shock absorber 110 from the vehicle frame 101 and a rear wheel 111 attached to a rear end of swing arm 109. The intake system of the engine (not shown in the figure) comprises of a carburettor, intake duct and an air cleaner. The exhaust system of the engine 108 comprises of exhaust pipe 202 and a muffler 205.

The motorcycle is also provided with a side cover for covering a side section of the vehicle frame 101, a front fender 113 for covering an upper part of the front wheel 104, and a rear fender 114 for covering an upper part of the rear wheel 111.

A motorcycle having an engine 108 and a transmission means, wherein a centrifugal clutch assembly 301 is used as a means for transmission of power from the engine 108 to the wheels 111. The said centrifugal clutch assembly 301 comprises of a carrier plate 302 welded with a hub 303 and a pair of pivot pins 304 attached to the carrier plate 302 away from the centre of the hub

303. A pair of clutch shoes 305 are pivotally mounted on the pivot pins 304 and prevented from coming out of the pivot pins 304 by a pair of circlips 306 assembled on the pivot pin 304. The shoes 305 are provided with a pair of hooking holes or openings and a pair of springs 307 are mounted between the shoes 305. Clutch shoes 305 are placed in such way that side opposite to pivot point of any shoe 305 is closer to pivot point of the other shoe 305. The primary damper 308 is placed at the end of the clutch shoe 305 opposite to the pivot point. Primary dampers 308 are used to avoid jerks and rubbing of the clutch shoes 305 during the working of the clutch. Shoes are provided 305 with its outer diameter being attached with a friction lining material 309. According to one of the embodiments of the present invention, a secondary damper 310 preferably rubber is provided around the hub 303. This secondary damper 310 rigidly holds the hub 303. A groove 311 is made on the circumference of the hub 303 which is aligned to a projection in the inside surface of the secondary damper 310, thus making the said damper 310 to be fitted perfectly and tightly on to the hub 303. During the operation of the clutch shoes 305, the inner portion of the said clutch shoe 303 rest on the above said damper 310, and as a result the noise produced due to the chattering of the shoes 303 are reduced considerably even in the likely event of the failing of the primary damper 308.

Any other suitable elastomer can also be used as the said secondary damping material.
As a result of the above said provision on the hub 303 the operational life of the clutch assembly 301 is increased considerably.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

Claims: We claim:

1. A clutch for a motorcycle comprising a carrier plate 302 welded with a hub 303, a pair of pivot pins 304 attached to the said carrier plate 302 away from the centre of the said hub 303, pair of clutch shoes 305 pivotally mounted on the said pivot pins 304, wherein a damper 310 is provided around the said hub 303.

2. The clutch for a motorcycle as claimed in claim 1, wherein the said damper 310 is preferably an elastomer.

3. The clutch for a motorcycle as claimed in claim 1, wherein a groove 311 is made on the circumference of the hub 303 that is aligned to a projection in the inside surface of the secondary damper 310.

4. A motorcycle having a clutch as claimed in claim 1.