The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine: gasoline (also called a spark-ignition engine) and diesel (also called a compression-ignition engine). Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the power train.
发动机作为动力设备，常见的类型是内燃机，其原 理是通过发动机缸内的液体燃料燃烧而产生能量。 发动机 // 内燃机 // 汽油 (点燃式)//柴油(压燃式) 发动机可分为两类：汽油机(点燃式)和柴油机 //热力发动机//动力传动系 (压燃式),都属于热力发动机。燃料燃烧产生热 量使缸内气压上升，产生的能量驱动轴旋转，并传 递给动力传动系。