Starter, also known as motor, converts the electric energy of battery into mechanical energy and drives the engine flywheel to rotate to realize the start of engine. As we all know, the starting of the engine needs the support of external force, and the car starter is playing this role. Generally speaking, the starter uses three parts to realize the whole starting process. The DC series motor introduces the current from the battery and makes the driving gear of the starter produce mechanical movement; The driving gear is meshed into the flywheel ring gear by the transmission mechanism, and can be disengaged automatically after the engine starts; The starter circuit is controlled by an electromagnetic switch. Among them, the motor is the main part of the starter, and its working principle is the process of energy conversion based on Ampere's law that we are exposed to in junior high school physics, that is, the effect of the force on the electrified conductor in the magnetic field. The motor consists of necessary armature, commutator, magnetic pole, brush, bearing and shell. Before the engine runs with its own power, it must rotate with the help of external force. With the help of external force, the process of engine transition from static state to self operation is called engine starting. There are three common starting modes of engine: manual starting, auxiliary gasoline engine starting and electric starting. Manual starting adopts the way of rope pulling or hand shaking, which is simple but inconvenient, and has high labor intensity. It is only suitable for some small power engines, and only reserved as a backup way in some cars; Auxiliary gasoline engine starting is mainly used in high-power diesel engine; Electric starting mode is easy to operate, quick to start, with the ability of repeated starting, and can be controlled remotely, so it is widely used in modern cars.