This invention relates to a starting system for a motor vehicle] more particularly, though not exclusively, to the starting system for the engine of a two and three wheeler motor vehicle.

Currently in many two and three wheeler motor vehicles, a starter motor is provided to crank the engine for starting the vehicle in addition to kick starting means. The capacity of the starter motor used for such application is in the range of 200 to 600 Watts for engine capacity ranging from 75cc to 400cc. As the engine capacity increases the starter motor capacity also needs to be increased. For normal electric starting, the cranking speed of magneto is 400 to 500 rpm for providing sufficient energy to generate the spark at predetermined ignition timing for subsequent running of engine.

In the known type of ignition system the required spark energy is produced either by an AC or DC ignition system (DC capacitor discharge type or DC inductive type). In the AC type ignition system the spark energy is generated from the magneto source coil and for DC system the said energy is from the battery source. Generally in the AC type ignition system, the spark energy available during electric start is half of DC type ignition. The timing at which the spark is generated is determined by a crank sensor (pulsar coil) with respect to a pip provided on the outer surface of the magneto rotor. The pulsar coil output which is an AC signal requires a minimum threshold voltage for producing sufficient spark energy for a given rpm. Vehicle manufacturers have therefore shifted to DC ignition for better startability and reliability under all conditions although the cost is more in such systems. However even in the case of DC ignition, the pulsar coil requires a minimum cranking speed of 400 to 500 rpm to generate sufficient threshold voltage for producing adequate spark energy, which is inevitable. For cranking the engine by the electric motor to the required rpm by overcoming the engine inertia, the power of the said motor will vary depending upon engine capacity which is in the order of 200 to 600 W for 75cc to 400cc. This in turn results in the need for providing higher capacity battery in the order of 12V 5Ah to 14 Ah and a higher capacity starter relay of contact rating 50 A to 100A. The function of starter relay is to carry the high current from the battery to starter motor at the time of electric start which will be more than 200A at the initial crank for a few seconds and running average current of 30 to 35A. The purpose of the starter relay is to prevent higher current flowing to the control switch at the time of starting.

Consequent to the above functional requirement of producing spark energy at a cranking speed of 400 to 500 rpm, the overall system cost consisting of starter motor of higher capacity, battery of higher rating, starter relay of higher contact rating is more. The system weight is also more. Furthermore, in the case of such engines, during cold starting, if reverse rotation of magneto takes place, the unnecessary signal produced by the pulsar coil generates a spark at wrong ignition timing resulting in a kickback and safety concern to the rider. This also causes considerable damage and failure of the starter motor and related mechanical parts during electric starting.

The objective of this invention is to ;

1) Produce adequate spark energy at significantly lower cranking rpm

2) Avoid wrong sparking during reverse rotation of the magneto

3) Reduce the total system cost

4) Reduce the overall weight of the electric starting system

5) To improve charging efficiency of the battery.

According to the present invention, the system consists of a DC ignition system (DC capacitor discharge type or DC inductive type) having a magneto which is mounted on the crankshaft of the engine, at least one Hall Effect sensor for sensing movement, regulated rectifier, battery, Ignition switch, Ignition controller, Ignition coil (capacitor discharge type or Inductive type), spark plug and a Starter motor substent comprising a starter switch, starter relay, starter motor & battery. The DC ignition system and starter motor sub are electrically connected. The Hall Effect sensor is mounted on the engine crankcase so as to sense the position of the pip provided on the magneto rotor. The pip location on the rotor is at predetermined position with respect to dead center of the engine. The output signal of the said Hall effect sensor which is a square pulse is fed to Ignition controller and the energy required for spark is taken from battery supply through' an ignition switch. The output of the ignition controller is fed to the ignition coil which in turn goes to the spark plug for initiating the spark at the predetermined ignition timing.

For electric starting, a starter motor is fitted on the engine and the motor shaft is coupled to the rotor though' known gear means. The starter motor is electrically connected to a battery supply through a starter relay. The relay is energized by a starter switch. A regulated rectifier supplies regulated DC voltage to battery for charging when the engine is running. The specification of the starter motor is, for example, in the range of 25W to 120W in the engine capacity ranging from 35cc to 400 cc. The battery rating for the said range of motor is 12V, 1.5Ah to 2.5Ah, with starter relay of maximum of 20A contact current rating.

When the ignition switch is ON, and the starter switch is activated, the starter relay gets energized. The starter motor will receive the supply voltage from the battery through the starter contact. The starter motor will crank the engine. Due to rotation of the magneto the Hall effect sensor will produce a square signal irrespective of the cranking rpm unlike the pulsar coil which requires a minimum cranking rpm to produce threshold AC voltage signal. Due to the provision of Hall effect sensor, high energy spark is produced irrespective of cranking rpm. The need for usage of higher power rated starter motor can therefore be avoided since the cranking rpm required is significantly reduced. As a result of lower cranking rpm, the rating of battery and starter relay can be lowered considerably as compared to the present system.

Furthermore in the event the magneto rotates in the reverse direction, the Hall effect sensor, by virtue of its motion sensing, will not produce any signal and generate spark with wrong timing thus eliminating kick back. This completely eliminates the kick starter lever hitting the rider's leg during kick starting and also eliminates failure of the starter motor and the related mechanical parts during electric starting.

It will be appreciated that various other embodiments of the starting system proposed herein are possible without departing from the scope and ambit of this invention.

We Claim:

1. A starting system for a motor vehicle comprising a DC ignition system incorporating a magneto mounted on the crankshaft of the engine, at least one Hall Effect sensor mounted on the engine crankcase for sensing the movement of a pip provided on the magneto rotor, the pip location on the rotor being at a predetermined position corresponding to a predetermined ignition timing of the engine; an ignition controller for receiving the output signal of the Hall effect sensor, the output of the controller being fed to the ignition coil and thence to the spark plug of the engine for initiating a spark at the predetermined ignition timing, the said Hall effect sensor producing a square signal irrespective of the cranking rpm, generating a high energy spark irrespective of cranking rpm, the Hall effect sensor, however, producing no signal, and consequently no spark, during any rotation of the magneto rotor in the reverse direction.

2. A starting system as claimed in Claim 1 wherein the DC ignition system is of the DC capacitor discharge type.

3. A starting system as claimed in Claim 1 wherein the DC ignition system is of the DC inductive type.

4. A starting system for a motor vehicle substantially as herein described with reference to, and as illustrated in, the accompanying drawings.