Gain an in-depth understanding of the structure and function of the starter motor

Nov 09,2021

The starter motor, also known as a motor, its core function is to efficiently convert the electrical energy of the battery into mechanical energy. Through this conversion, it can drive the flywheel of the engine to rotate, thereby successfully starting the engine. This driving method is defined as one-way driving.
Gain an in-depth understanding of the structure and function of the starter motor

The starter motor, also known as a motor, its core function is to efficiently convert the electrical energy of the battery into mechanical energy. Through this conversion, it can drive the flywheel of the engine to rotate, thereby successfully starting the engine. This driving method is defined as one-way driving.

一. Structure and Working Principle of the Starter
The core component of the starter is a DC series-excited motor, whose rotor and stator are both finely wound with thick rectangular-section copper wires. It is equipped with a reduction gear drive mechanism and controls the starting process through an electromagnetic attraction operating mechanism. Overall, the starter is a precise combination of three major components: a DC motor, a one-way clutch, and an electromagnetic control switch.

二. Function
The main function of the starter motor is to efficiently convert the electrical energy stored in the battery into mechanical energy, which then drives the flywheel of the engine to rotate, thereby successfully starting the engine. This function allows the car to start smoothly, providing necessary support for daily driving.

 

三. Working Principle
The working principle of a starter motor can be summarized in three steps. First, when the car's ignition switch is turned on, the starter's solenoid switch is energized and activated. Second, through a series of mechanical actions such as attracting the iron core and pushing the gear, the solenoid switch connects the motor to the engine's flywheel. Finally, under the control of the solenoid switch, the motor starts to operate, efficiently converting the electrical energy from the battery into mechanical energy, thereby driving the engine's flywheel to rotate and successfully starting the engine. This series of actions constitutes the complete working process of the starter motor.

1. When the car's ignition switch is closed, two coil windings (the holding coil S-ground and the pull-in coil S-M) start to be energized. It is particularly noted that due to the extremely low resistance of the pull-in coil, the current passing through it is very strong. This coil is connected in series with the motor circuit, causing the motor to rotate slowly under the action of the current, so that the pinion can smoothly engage with the flywheel.

2. During this process, the magnetic field generated in the coil attracts the iron core, which in turn pushes the pinion to mesh with the flywheel ring gear. At this time, the heavy-load main contact B is short-circuited by the shorting piece, that is, the short-circuit switch is closed, thereby connecting the main circuit of the starter. The armature winding is supplied with a large current by the battery, generating a strong starting torque. At the same time, the pull-in coil (S-M) is short-circuited because the voltages at both ends are equal, while the holding coil (S-ground) continues to attract the iron core in a fixed position.

3. Once the ignition switch is turned off, the holding coil (S-ground) and the pull-in coil (S-M) are powered by the M terminal instead. At this time, the direction of the magnetic field generated by the pull-in coil (S-M) is opposite to that in the initial stage of startup, and it cancels each other out with the magnetic field of the holding coil (S-ground). This opposing magnetic force resets the iron core, and the main contact B is disconnected from M. Subsequently, the circuit of the DC motor is cut off, and the motor starts to decelerate and stop.

四. Potential reasons why the starter motor fails to rotate or rotates slowly:
1. Insufficient battery power or weak electricity, causing the starter motor to fail to rotate normally or rotate slowly.
2. Loose or disconnected starter motor wire connections, and failure of the switch or suction switch.
3. Severe wear or misalignment of the brushes, along with insufficient spring force, resulting in poor contact with the commutator.
4. Short circuit and open circuit problems in the field coil or armature coil.
5. Contamination on the surface of the commutator and protruding mica sheets, leading to poor contact between the brushes and the commutator.

Keyword:

Previous Page:

Automobile Starter One-Way Clutch: Comprehensive Analysis of Its Function, Structure and Application

Next Page:

None!