It is an internal-combustion engine that burns gasoline most automobiles. in theory diesel engine and gasoline engines are quite similar. They are both internal combustion engines designed to convert the chemical energy available in a fuel into mechanical energy. This mechanical energy moves the pistons up and down in the cylinders. The pistons are connected to crank shaft and the up and down motion of the pistons, known as linear motion, creates the rotary motion to turn the wheels of the car forward.
Both the diesel engine and gasoline engines covert the fuel into energy through a series of small explosions or combustions. The major difference in diesel engine and gasoline engine is the way in which these explosions are happen. In a gasoline engine, fuel is mixed with air, compressed by pistons and ignited by sparks from spark plugs. In a diesel engine, however, the air is compressed first, and then the fuel is injected. Because the air is heated up and it is compressed and ignited.
The diesel engine uses four stroke combustion cycle just like a gasoline engine. The four strokes are:
- Intake stroke -- The intake valve opens up, letting in air and moving the piston down.
- Compression stroke -- The piston moves back up and compresses the air.
- Combustion stroke -- As the piston reaches the top, fuel is injected at just the right moment and ignited, forcing the piston back down.
- Exhaust stroke -- The piston moves back to the top, pushing out the exhaust created from the combustion out of the exhaust valve.
Remember that the diesel engine has no spark plug, that it intakes air and compresses it, and that it then injects the fuel directly into the combustion chamber (direct injection). It is the heat of the compressed air that lights the fuel in a diesel engine. In the next section, we'll examine the diesel injection process.
