Claims:We Claim:
1. A mechanical supercharger assembly (100), comprising:
a supercharger (102) located upstream to an engine (104) and adapted to be driven by the engine crankshaft (202); characterized in that:
a variable speed drive (106) connected to said engine crankshaft (202) at a drive end (108)of said variable speed drive and a driven end (110)of said variable speed drive 106 connected to said supercharger (102).

2. The mechanical supercharger assembly (100) of claim 1, wherein said variable speed drive 106 is a pulley.

3. The mechanical supercharger assembly (100) of claim 1, wherein said drive end 108 comprises at least a pair of flyweights ( 200).

4. The mechanical supercharger assembly (100) of claim 4, wherein said at least one flyweight is connected to said engine crankshaft 202 via a spring (203).
, Description:Field of the invention
[0001] This invention relates to the field of supercharger.

Background of the invention
[0002] A supercharger is used to increase the volume of air supplied to an engine. Superchargers increase the intake by compressing air above atmospheric pressure, without creating a vacuum. This forces more air into the engine, providing a "boost." With the additional air in the boost, more fuel can be added to the charge, and the power of the engine is increased. To pressurize the air, a supercharger must spin rapidly, more rapidly than the engine itself. Making the drive gear larger than the compressor gear causes the compressor to spin faster. However at higher engine speeds there is a need to reduce the RPM of the supercharger in order to avoid over-compression of air. This is possible if we can map the performance of supercharger over the speed range with respect to the air flow. Hence there is a need to improve the flexibility of shaping air flow values over the entire speed range by regulating the speed of the supercharger.
[0003] Prior art patent application GB599800A discloses a change-speed gear having a plurality of lay shafts each of which has associated therewith a centrifugally-actuated clutch operable to connect the driving and driven shafts through gear trains, the step-up from one speed ratio to the next higher is accompanied by the employment of at least one more clutch connection and at the highest speed ratio torque is transmitted by the driving elements of all the clutches.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0005] FIG. 1 illustrates a mechanical supercharger assembly; and
[0006] FIG. 2 illustrates a drive for the supercharger.

Detailed description of the embodiments
[0007] FIG. 1 illustrates a mechanical supercharger assembly 100. The supercharger assembly 100 comprises a supercharger 102 located upstream to an engine and adapted to be driven by the engine crankshaft. A variable speed drive 106 is connected to the engine crankshaft 202 at a drive end 108 and a driven end 110 of the variable speed drive 106 connected to the supercharger 102The drive end 108 of the variable speed drive receives rotary motion from the engine crankshaft 202.The driven end 110 of the variable speed drives the supercharger 102. The working of the supercharger 102 will be explained in further detail. The supercharger 102 is driven by the engine 104. The supercharger 102 comprises a shaft that derives power from the crankshaft through a pulley mechanism. As the supercharger shaft rotates, the air that is drawn from the atmosphere via an air filter, get compressed and is sent to inlet of the engine 104. Whenever more power is required, the superchargers compresses a larger volume of air and delivers it to the inlet of the engine 104. The pulley is a variable speed pulley, the pulley can be designed to meet certain speed ratio between supercharger and the engine. The proposed layout enables to achieve Bharat Stage (BS 6) legislations in India.
[0008] FIG. 2 illustrates a drive for the supercharger 102. The variable speed drive 106 is connected to the engine crankshaft 202 at a drive end of the variable speed drive and the driven end 110 of said variable speed drive 106 connected to the supercharger. The drive end 108 consists of two flyweights 200 connected to crankshaft 202 via a spring 203 assembly. With increase in speed the flyweight 200 work against the spring and moves out pushing the ring which is connected by one or more springs 203. At higher engine speed the diameter of the drive input side increases there by reducing the speed of the supercharger 102. Variable speed pulley system should be designed specific to engine and vehicle requirement. With this the compression loss at full load and rated speed can be reduced to facilitate fuel economy. Due to regulation of speed in the supercharger 102, the air flow values can be regulated over the engine speed leading to lower compression pressure and engine friction.
[0009] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of type of. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.