Introduction Ignition Systems of SI Engine, What Are the Requirements of an Ignition System?

SI engine ignition systems

In a CI engine, air-fuel mixture gets ignited at a high compression ratio. But in an SI engine, it is not the case. The SI engine works the pressure ratio lower than that of CI engine. The SI engine requires an external source of an energy to initiate the combustion process. Engine ignition systems are the tools that used to ignite SI engine.

In a spark ignition engine, fuel ignited by an electrical discharge produced between the two adjacent electrodes. The small spark energy of few micro-second is enough for the purpose. This is achieved by using the device is known as a spark plug. The whole system that runs the spark plug is known as the ignition system. Based on how the primary energy required for operating spark plug obtained, the ignition system divided in to

• Battery ignition system
• Magneto ignition system
• Electronic ignition system

What are the requirement or Desirable conditions of an ignition system?

Following are the essential requirement of an ignition system for a smooth and reliable operation of the ignition system

• It should provide a good spark between the electrodes of spark plug at the correct timing
• The duration of spark must be long enough to give sufficient energy to ensure ignition.
• The ignition system should work efficiently in the entire speed range of an engine.
• The high voltage and magnetic field produced by ignition system should not interfere with the other electronic devices in the automobile.
• It should be cheap and reliable.
• It should be light, compact and easy to maintain.