This invention relates to an electric starter system for hybrid motor vehicles, particularly, hybrid motorcycles, scooters and other hybrid motor vehicles to which the said device is found applicable.

Currently, hybrid vehicles, such as, hybrid motorcycles and scooters, use a 36/48 Volt battery exclusively for supplying tractive power, that is to say, for supplying electric power to a motor for driving the vehicle in motor mode. On the other hand, on the engine side of such vehicles, electric starters are used for starting the engine whenever it is required to run the vehicle on engine mode. Accordingly, these vehicles employ a l2Volt battery and a mechanical relay connected to a 12V DC starter motor for starting the engine. The starter motor cranks the engine to a few hundred rpm, after which the engine sustains itself once combustion takes place. Such vehicles use the 12 Volt battery not .only to start the engine, but also to power electric loads, such as, vehicle lights, horn and the like,

However, a 12 Volt battery system is not very efficient for high transient power loads, such as, the starter motor, since it has to deliver a high current to meet the transient power demand for a heavy motor torque. This high current not only stresses the battery but the mechanical relay as well. Besides, a hybrid vehicle has many starts and stops, compared to the conventional non-hybrid (solely engine driven) vehicle, for the purpose of saving fuel, among other reasons. These stop start situations ultimately take their toll on the 12 Volt battery and worsen the existing problem.

It is therefore the object of this invention to propose an electric starter system for a hybrid motor vehicle of the kind particularised above, for eliminating or, at least, minimizing, the above mentioned drawbacks, to which the known electric starter system is prone.

This invention will now be described with reference to the accompanying drawings which illustrate the concept.

In Fig. 1 the circuit layout of the known starter system of a hybrid vehicle

And in Fig. 2 , by way of example, and not by way of limitation, one of possible embodiments of this invention.

It will be observed from Fig. I that the traction motor Ml is connected to, and powered exclusively by the battery B I while the starter motor M2 is connected to, and powered exclusively by, the battery B2, the two battery circuits being installed in parallel The battery B1 is of higher voltage (e.g. 36/48V) than the battery B2 (e.g. 12 volts). It will be noted that the battery B2 is also connected to the lighting and other regular loads of the vehicle. In other words, not only has the battery B2 to supply power to the starter motor M2 for starting the engine of the vehicle, but, additionally, has to supply power to the lighting and other regular loads of the vehicle, in the course of which this battery registers a lower efficiency than that desired. Apart from this aspect of the matter, the provision of battery B2 entails use of space for accommodating it. inside the vehicle, together with periodic maintenance and service to keep it going. All this adds up in terms of manhours and expense,

On the other hand, it will be observed from the embodiment in Fig. 2 that the traction motor Ml is connected to, and powered by, the battery B1 while the starter motor M2 is also connected to, and powered by, the battery B1, the battery B2 being dispensed with. The input rating of the motor M2 will now conform to the output rating of the battery B1. Furthermore, the two motor circuits (the traction motor and the starter motor circuits) are now installed in parallel unlike the conventional arrangement wherein two battery circuits were installed in parallel. Additionally, in the embodiment illustrated, battery Bl is also connected to the lighting and other regular loads of the vehicle, thus serving the triple need of supplying the traction load, the starter load, the lighting and other regular loads of the vehicle. The elimination of battery B2 results in space saving within the vehicle, along with the elimination of periodic maintenance and service of the battery to keep it going, all this adds up in terms of saving manhours and expense.

It will be appreciated that various other embodiments of this invention are possible without departing from its scope and ambit.

We claim:

1. An electric starter system for a hybrid motor vehicle wherein a traction motor connected to, and powered exclusively by, a first battery; a starter motor connected to, and powered exclusively by, a second battery, the first battery being of higher voltage than that of the second battery, the two battery circuits being installed in parallel, with the second battery also connected to the lighting and other regular loads of the vehicle is characterized in that the traction motor is connected to, and powered by, the first battery, while the starter motor of input voltage , conforming to the output voltage of the first battery, is also connected to, and powered by, the first battery, the second battery being dispensed with, the two motor circuits being installed in parallel, while the lighting and other regular loads of the vehicle are connected to the first battery.

2. An electric starter system for a hybrid motor vehicle substantially as herein described with reference to, and as illustrated kin, the accompanying drawings.