Principal Components Engines

     The engine acts as the power unit, which is designed to convert energy into usefulmechanical motion. The internal-combustion engine（ICE）is widely used in modernautomobile.  The internal-combustion engine is a device used to convert the chemicalenergy of the fuel into heat energy, and then to convert this heat energy into usablemechaniWl energy. The working process includes four strokes, which are intake stroke，compression stroke, power stroke and exhaust stroke. In practical work, the reciprocatingmovement of piston in the cylinder is converted to rotary motion of the crankshaft. Theinternal-combustion engines can be divided into two types：gasoline（spark-ignitionengine) and diesel (compression-ignition engine)．