This invention relates to a hybrid power system and more particularly to a hybrid power system to be used in conjunction with a small internal combustion engine and an electric motor for two wheeler motor vehicles.
Conventionally, a vehicle is driven by an internal combustion engine. An internal combustion engine generates power that is transmitted to wheels to drive the vehicle. Internal combustion engines consume fuel and also pollute the atmosphere. In order to conserve fuel and for protecting the environment, electrically driven vehicles have been developed having no internal combustion engines. In an electrically driven vehicle, electric energy which is stored in a battery is converted to mechanical energy by an electric motor. Mechanical power is delivered by gearing coupled to the wheels. However, batteries have limited storage capabilities, so much so that the range of travel for electrically driven vehicles is insufficient and generally does not meet motorists' demands and are therefore not widely used. For this reason, vehicles driven by hybrid power systems have been developed, most of them having an engine and an electric motor.
Currently, hybrid power systems are mostly used in four-wheel motor vehicles. However small vehicles, such as, two wheelers which are driven by a small engine, have little space and need to be inexpensive. It is difficult to install transmission devices for hybrid power systems in small vehicles. Consequently, very

few hybrid power systems are used in small vehicles. Although some research is being done and several attempts have been made, there is only a narrow range of applications of hybrid power systems on small vehicles.
In a known type of hybrid engine for two wheelers, the engine power is transmitted through a known type of continuous variable transmission (CVT) then through a centrifugal clutch and a secondary gear box to the rear wheel. An electric motor is mounted on the rear wheel or on the engine crankshaft for hybrid operation. The CVT system is employed for the convenience of the motorist since there is no need tor any gear shifting, but inherently the CVT system has low transmission efficiency due to friction, hysteresis loss and belt slip. Consequently, such vehicles give higher fuel consumption and higher emissions. This can be overcome by introducing manual gear shift mechanisms with electric motor for hybrid operation with extra cost and inconvenience to the user.
It is therefore an objective of this invention to provide a hybrid power system for a two wheeler motor vehicle with optimum transmission efficiency, lower fuel consumption and lower emissions without sacrificing convenience.
The hybrid power system for a two wheeler motor vehicle, according to this invention, comprises an IC engine and an electric motor, the engine and motor being respectively coupled to a wheel of the vehicle; a fiiel tank, an ignition system, a

continuous variable transmission system, dutch and a
secondary gear box provided for the engine; a battery
connected to the motor; and a fixed transmission system .
positioned between the engine and the secondary gear box.
This invention will now be described with reference to the accompanying drawings which illustrate, by way of example, and not by way of limitation, embodiments of this invention, wherein
Fig. 1 illustrating an embodiment with a fixed transmission system (chain drive or belt drive) provided between engine and secondary gear box for good transmission efficiency.
Fig. 2 illustrating another embodiment with a fixed transmission system (chain drive or belt drive) provided between engine and secondary gear box for good transmission efficiency.
Fig. 3 illustrating yet another embodiment with a fixed transmission system(chain drive or belt drive) provided between engine and secondary gear box for good transmission efficiency.

According to the first embodiment of this invention, the hybrid power system consists of a chain drive D and a fixed ratio secondary gear box G. E is the engine and B is the battery. FT is the fuel tank. The engine power is transmitted through a positive chain drive D instead of a conventional CVT system, then through a centrifugal clutch C and the secondary gear box G to the rear wheel W otlhe vehicle. An electric motor M is mounted over the wheel shaft or in any other suitable place for hybrid operation.
According to the second embodiment of this invention, the hybrid power system consists of a fixed ratio transmission belt, H such as, a toothed belt between the engine and the secondary gear box. The engine power is transmitted through the toothed , belt, then through a centrifugal clutch C and a secondary gear box G to the rear wheel W of the vehicle. An electric motor M is mounted over the crankshaft or in any other suitable place for hybrid operation.
According to the third embodiment of this invention, the hybrid power system consists of a fixed ratio transmission belt, H such as, a toothed belt between the engine E and the secondary gear box G. The engine power is transmitted through the toothed belt, then through a centrifugal clutch C and a secondary gear box G to the rear wheel W of the vehicle. An electric motor M is mounted over the belt drive or in any other suitable place for hybrid operation.

It will be appreciated that this invention is not confined to the embodiments herein described and illustrated but that various other embodiments thereof are possible without departing from the scope and ambit thereof.

We Claim:
1. A hybrid power system for a two wheeler motor vehicle comprising an IC engine and an electric motor, the engine and motor being respectively coupled to a wheel of the vehicle; a fuel tank, an ignition system, a continuous variable transmission system, clutch and a secondary gear box provided for the engine; a battery connected to the motor, and a fixed transmission system positioned between the engine and the secondary gear box.
2. A hybrid power system for a two wheeler motor vehicle as claimed in Claim 1 wherein the fixed transmission system consists of a belt drive.
3. A hybrid power system for a two wheeler motor vehicle as claimed in Claim I wherein the fixed transmission system consists of a chain drive.
4. A hybrid power system for a two wheeler motor vehicle wherein the clutch is a centrifugal clutch.
5. A hybrid power system for a two wheeler motor vehicle as claimed in any one of the preceding Claims wherein the electric motor is mounted over the wheel shaft
6. A hybrid power system for a two wheeler motor vehicle as claimed in any one of the Claims I to 4 wherein the electric motor is mounted over the crankshaft.
7. A hybrid power system for a two wheeler motor vehicle as claimed in any one of the preceding Claims 1 to 4 wherein ihe electric motor is mounted over the chain drive.

8. A hybrid power system for a two wheeler motor vehicle
as claimed in any one of the preceding Claims I to 4
wherein the electric motor is mounted over the belt
drive:
9. A hybrid power system for a two wheeler motor vehicle
substantially as herein described with reference to, and
as illustrated in, the accompanying drawings.