ELECTRIC START SYSTEM FOR A VEHICLE

FIELD OF THE INVENTION

The invention relates to an electric start system for an internal combustion engine and more particularly for two wheeled vehicles.

DESCRIPTION OF THE PRIOR ART

Most vehicles with an internal combustion engine have an electric start system wherein an electric motor cranks the engine using the electrical energy supplied by a vehicle battery, for this purpose high current is drawn from the battery resulting in deep discharge of the battery voltage. Generally a battery charging system in a vehicle, comprising of magneto and rectifier-regulator unit, helps in charging the battery. But if the vehicle is not used regularly, the battery state of charge reduces due to self-discharge. It is undesirable to run the motor at low battery state of charge, as it will cause instantaneous discharge of the battery and can degrade battery life as well. Therefore it is required to determine the battery voltage before cranking of the engine starts and intimating the same to the operator. In the known prior art, determining the voltage of the battery and indicating the operator about the low state of charge of battery is known.

But such a system does not restrain the operator to perform electric start of the vehicle even if low battery charge is indicated. Also pursuant to this the battery capacity is measured only during cranking. As a result unnecessary attempts are made by the operator to start the vehicle using electric start switch, whereby it leads to degradation of battery life. In addition to this stated problem, the operator has to face a continuous noise due to failure of the electric start system. Therefore, an electric start system for an internal combustion is suggested that overcome these problems.

SUMMARY OF THE INVENTION

As a means to overcome above-mentioned drawbacks, the present invention is applicable to an electric start system for a vehicle with internal combustion engine. In accord with this invention, an electric start system for a vehicle with internal combustion engine and an electric start indication means are provided, wherein the electric starting ability is monitored before cranking of the engine, based on which the electric start system is enabled or disabled and same is indicated to the operator by an indicating means. During cranking the electric motor accelerates the crankshaft assembly to a speed at which the engine can sustain combustion. For this purpose high current is drawn from the battery, therefore it is an objective of the present invention to determine the starting ability of the battery before cranking of the engine starts and accordingly to restrain the rider from electrically starting the vehicle if batteries supply voltage is below the predetermined voltage limit.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 illustrates an electric start system according to the present invention.

DETAILED DESCRIPTION OF THE DRAWING

Pursuant to this invention, in Figure 1 a battery 10 is connected with a starter motor 20 through a starter relay 30. The starter motor 20 is mechanically connected with engine to accelerate a crankshaft assembly of the engine when starter relay 30 is energized. A dynamic test is performed every time the operator switches ON an ignition switch 90 (Ig switch). Before cranking of the engine, an engine coolant temperature and a battery voltage are measured. A lookup table is provided which contains the predetermined voltage limit corresponding to a minimum engine coolant temperature and battery voltage required for successful electric starting. An electronic control unit 50 (ECU) receives measured engine coolant temperature, battery voltage and engine speed signals. The ECU 50 compares this measured battery voltage with the predetermined voltage limit stored in the look up table and checks whether measured battery voltage for the measured engine coolant temperature is greater than the predetermined voltage limit as specified in the look up table. Further if the measured battery voltage is greater than the predetermined voltage limit, the electric start system of the vehicle is enabled and the operator can perform the electric start operation, else it is disabled and the operator will be restrained from performing the electric start of the vehicle thus preserving the battery life from degrading, also the electric starting ability is indicated to the operator.

The ECU 50 calculates engine rpm based on an engine speed sensor 70 signal. If the engine speed is equal to zero, the ECU 50 calculates engine coolant temperature from a temperature sensor 60 and also measures battery voltage. The ECU 50 checks if the measured battery voltage is greater than the predetermined voltage limit as specified in the look up table for the measured engine coolant temperature. If yes, then the ECU 50 enables electric starting of the vehicle. An electric start inability indication is not activated and when the Ig switch 90 and an electric start switch 100 (ES switch) are ON, the ECU 50 energizes starter relay 30 and the engine can be started by electric start. But if the measured battery voltage is less than the value specified in look-up table for the measured engine coolant temperature, then electric start is disabled and the electric start inability is indicated to the operator. Even if both Ig switch 90 and ES switch 100 are ON, the starter relay 30 will not be energized. Hence electric starting is prevented during low state of charge of battery. After enabling or disabling the electric start function, the ECU 50 continues with other control operations. The electric start indicating means is preferably an audio alert or a visual alert and can be placed on the handle bar. The indicating means can be displayed within a speedometer 80. The predetermined voltage limit for electric start of vehicle is 11 V for engine coolant temperature exceeding 60 degree Celsius.

WE CLAIM:

1. A method to determine the electric start-ability before cranking of an internal combustion engine of an electric start system comprising the steps of:

Sensing engine rpm using an engine speed sensor, if engine speed is zero continue further operation;

Measuring an engine coolant temperature using a temperature sensor;
Measuring battery voltage;

Comparing the measured battery voltage with a predetermined voltage limit stored in a look up table for the measured engine coolant temperature by an Electronic Control unit (ECU);

Enabling or disabling the electric start system based on ECU output, wherein the electric start system is enabled if the measured voltage is greater than the predetermined voltage limit mentioned in the look up table, else the electric start system is disabled; and

Activating or deactivating an indicating means for electric start system based on ECU output and warning the operator about the low starting ability of the battery.

2. An electric start system for an internal combustion engine comprising:

a starter motor having a starter relay;

a battery, connected to the starter motor and provides electrical energy to the motor for cranking the internal combustion engine;

an ignition switch to switch on the ignition;

an electric start switch to perform electric start;

a temperature sensor for sensing the engine coolant temperature;

an engine speed sensor to determine the speed of the engine;

an electronic control unit, for comparing measured battery voltage with predetermined voltage limit corresponding to a minimum engine coolant temperature and battery voltage as stored in a look up table for the measured engine coolant temperature and generate output signal; and an indicating means is provided to indicate the enabled or disabled mode of the electric start system based on the ECU output signal.

3. The electric start system for an internal combustion engine as claimed in claim 1 and claim 2, wherein the indicating means is preferably audio alert or visual alert.

4. The electric start system for an internal combustion engine as claimed in claim 1 and claim 2, wherein the indicating means is placed on a handle bar.

5. The electric start system for an internal combustion engine as claimed in claim 1 and claim 2, wherein the indicating means is preferably displayed within a speedometer.

6. The electric start system for an internal combustion engine as claimed in claim 1 and claim 2, wherein the predetermined voltage limit is 11 V for engine coolant temperature exceeding 60 degree Celsius.

7. The electric start system for an internal combustion engine substantially as herein described in the specification and as illustrated in the accompanying drawings.