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Electronic Ignition System and Its Advantages

 There are some drawbacks in the above discussed magneto ignition system. Firstly, the contact breaker points will wear out or burn when it is operated with heavy current.

Secondly, the contact breaker is only a mechanical device which cannot operate precisely at higher speed due to the reason that the dwell period is not sufficient for building up the magnetic field to its full value at that speeds. The conventional contact breaker can give satisfactory performance only at about 400 sparks per second which limits the engine speed. At low speeds, relatively high current is drawn from the battery due to the contacts remaining closed for longer time. Thus, the system becomes inefficient at low speeds.

The disadvantages of the conventional contact breaker assisted ignition system can be completely eliminated by the use of electronic controlled ignition system using contactless triggers to give timing system. The basic difference between contact point and the electronic ignition systems is in the primary circuit. In the contact breaker system, the primary circuit is opened and closed by electronic control unit. The secondary circuits are practically same as the previous systems. 

In secondary circuit, the distributor , ignition coil, and wiring are altered to handle the higher voltage that the electronic ignition system produces. The high voltage ( 47000 volts) has the advantage that the spark plug with wider gaps can be used. This results in a longer spark which can ignite leaner air -fuel mixtures. As a result, engines can run on lean mixtures for better fuel economy.

Construction :

 It consists of  a battery, ignition switch, electronic control unit, magnetic pick-up, reluctor or armature, ignition coil, distributor and spark plugs. 


Working of Electronic Ignition System :

When the Ignition System is closed (i.e, Switch is 'ON') , the reluctor rotates which makes the teeth of the reluctor cone closer to the permanent magnet. It reduces the air gap between the reluctor tooth and the sensor coil. 

Thus the reluctor provides a path for the magnetic lines from the magnet. The magnetic field is passed onto the pickup every time when the reluctor teeth pass the pick up coil in which an electric pulse is generated. This small current then triggers the electronic control unit which stops the flow of battery current to the ignition coil. 

The magnetic field in the primary winding collapses and the high voltage is generated in the secondary winding. It leads to the spark in spark plug via distributor. Mean while, the reluctor teeth pass past the pickup coil. Therefore, the pulse unit is ended. It causes the electronic control unit to close the primary circuit.

Advantages :

1. The parts such as reluctor, magnetic pickup and electronic control unit are not subjected to wear as incase of  mechanical contact breaker.

2. Periodic adjustment of engine timing is necessary.

3. It gives very accurate control of  timing.

 

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