What Is the Working Principle of Starter Electromagnetic Switch?

Electromagnetic switch is a switch device controlled by electromagnetic. It is widely used in various industries. The most common contactor is in the industrial field. It is also used in agriculture, such as tractor parts and agricultural machine. According to the principle of electromagnetic induction, passing current to the conductor (coil), its coil will produce corresponding magnetic field. At the same time, the conductor in the magnetic field is affected by ampere force to produce directional movement. Thus, the working scene of electromagnetic switch is formed.

 

 

1. Composition

The electromagnetic switch is mainly composed of the following parts.

(1) Electromagnetic induction part: pull coil, holding coil, coil frame and guide sleeve.

(2) Directional moving part: moving iron core, moving contact piece and static iron core.

(3) Device structure part: contact screw, switch cover and switch housing.

 

 

2. Main Functions

The electromagnetic switch is mainly applied as a mechanism to turn on or off the circuit between the battery and the starter.

 

(1) In the process of switching on, the switch coil is energized to generate electromagnetic attraction, which makes the moving iron core move. Thus, on the one hand, the fork is pulled to make the starter drive pinion move forward to engage with the engine flywheel ring gear. On the other hand, the moving contact is pushed to make the contact between the moving contact and the contact screw contact connected, and the circuit between the battery and the starter is connected. Then the DC motor is energized for operation, so as to drive the engine to start.

 

(2) In the process of disconnection, when the main circuit is disconnected, the starter drive pinion is disengaged from the flywheel ring gear and returns smoothly.

 

 

3. Working Principle

The working principle of electromagnetic switch in vehicle environment is as follows.

 

When the key switch of the car is closed and the starter is powered on, the switch coil is powered on and the moving iron core is attracted to move. When the moving iron core is closed with the static iron core (The bottom of the moving iron core is close to the end face of the top iron core), the moving contact piece will connect Terminal B and M. At this time, the battery voltage is directly applied to the starter to make the starter armature rotate. The movement of the switch moving iron core pulls the fork to make the driving gear extend out of the starter engine. Turn off the start-up key switch (The ignition relay control is powered off or the key switch is manually turned off after the engine is ignited successfully). The power in the solenoid switch coil is cut off due to the circuit disconnection, and the magnetic flux disappears. The moving contact piece disconnects the contact screw due to the return spring reset function, then the starter circuit is disconnected, and the starter stops working.

 

Electromagnetic switch is a key part of a starter. Different types of electromagnetic switches of different machines will be different, but their working principles are basically the same. Starter is also one of the common tractor parts and agricultural machine, people need to know more about it.