Ignition System

Introduction:
                In case of Internal Combustion (IC) engines, combustion of air and fuel takes place inside the engine cylinder and the products of combustion expand to produce reciprocating motion of the piston. This reciprocating motion of the piston is in turn converted into rotary motion of the crank shaft through connecting rod and crank. This rotary motion of the crank shaft is in turn used to drive the generators for generating power.

 

Ignition system in petrol engines:
           

• In case of petrol engines during suction operation, charge of air and petrol fuel will be taken in.
• During compression this charge is compressed by the upward moving piston.
• And just before the end of compression, the charge of air and petrol fuel will be ignited by means of the spark produced by means of for spark plug.
• And the ignition system does the function of producing the spark in case of spark ignition engines.
• Figure shows atypical spark plug used with petrol engines.
• It mainly consists of central electrode and metal tongue.
• Central electrode is covered by means of porcelain insulating material. Through the metal screw the spark plug is fitted in the cylinder head plug.
•  When the high tension voltage of the order of 30000 volts is applied across the spark electrodes, current jumps from one electrode to another producing a spark.

                                      

 

Ignition system in diesel engines:

• In case of diesel (Compression Ignition-CI) engines only air is taken in during suction operation and in compressed during compression operation and just before the end of compression, when diesel fuel is injected; it gets ignited due to heat of compression of air.
• Once the charge is ignited, combustion starts and products of combustion expand, i.e. they force the piston to move downwards i.e. they produce power and after producing the power the gases are exhausted during exhaust operation.

 

IGNITION SYSTEM TYPES:

Basically Convectional Ignition systems are of 2 types:

                (a) Battery or Coil Ignition System: Battery ignition system was generally used in 4-wheelers, but now-a-days it is more commonly used in 2-wheelers also (i.e. Button start, 2-wheelers like Pulsar, Kinetic Honda; Honda-Activa, Scooty, Fiero, etc.). In this case 6 V or 12 V batteries will supply necessary current in the primary winding.

                (b) Magneto Ignition System: Magneto ignition system is mainly used in 2-wheelers, kick start engines. (Example, Bajaj Scooters, Boxer, Victor, Splendor, Passion, etc).In this case magneto will produce and supply current to the primary winding.