Spark and Ignition (1)

Spark and Ignition (1)

 

Both of Diesel and Gasoline engine use a cylinder (more precisely, combustion chamber) to generate power to rotate crankshaft. Air and fuel mixture in the combustion chamber burns (or explodes) and the explosion pressure push down the piston connected to crankshaft.  The diesel fuel has lower temperature point of ignition than gasoline around 250 deg C, and this temperature can easily be generated only by compressing air. This means, it is not necessary to have a special device to give an ignition for diesel engine. But the story of gasoline engine is different. The gasoline fuel has lower temperature point of flashing but not ignition. Means we need to give a kind of device to give  an impulse to be ignited to the gasoline and air mixture. In this chapter the principle of this device “Spark and Ignition Device in Gasoline engine” will be explained.

 

 

 

We call “Idling” when an engine is running without any external load. The idling speed is different engine by engine but typically the speed is in the range of 500 rpm to 800 rpm in warm engine. In case of 800 rpm, the engine rotates 13 times in a second means 26 times of “spark” supply is necessary (4 cylinder engine case). With which device can the engine supply such a constant and speedy spark energy to the mixture ? We can call this device as an “artificial lightening machine”. This spark-ignition device is a unique high voltage generating electrical device in the vehicle, most of the other driving devices are composed by mechanical parts and components.

 

Before talking about the principle of ignition system, let’s think about the lightening and thunderbolt at the monsoon season. The lightening comes between two groups of cloud which contains different charge level, if the charge level is different enough to lead a discharging with very big spark. The thunderbolt is the same thing but we call it thunderbolt when it happens not between clouds but cloud and earth. Exactly same thing happens at the spark plug installed at gasoline engine combustion chamber.

 

To be continued at part (2) …

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