How the starter works

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How the starter works

The control device of the automobile starter includes an electromagnetic switch, a starter relay and an ignition start switch lamp component, wherein the electromagnetic switch is made together at the starter.

First, the electromagnetic switch

1. Electromagnetic switch structure features

The electromagnetic switch is mainly composed of an electromagnet mechanism and a motor switch. The electromagnet mechanism is composed of a fixed iron core, a movable iron core, a suction coil, and a holding coil. The fixed iron core is fixed and the movable iron core can be moved axially in the copper sleeve. A push rod is fixed to the front end of the movable iron core, and a switch touch panel is installed at the front end of the push rod, and the rear part of the movable iron core is connected with the shift fork by an adjusting screw and a connecting pin. A return spring is mounted on the outside of the copper sleeve to reset the movable member such as the movable iron core. The arrangement position of the terminals of the electromagnetic switch wiring is as shown

2. The working principle of electromagnetic switch

When the magnetic flux directions generated by energizing the attracting coil and the holding coil are the same, the electromagnetic attraction forces are superimposed on each other, and the moving iron core can be attracted to move forward until the touch panel at the front end of the push rod turns the electric switch contact to close the potential motor main circuit. .

When the magnetic coil caused by the energization of the attracting coil and the holding coil is opposite in direction, the electromagnetic attraction cancels each other. Under the action of the return spring, the movable member such as the movable iron is automatically reset, the contact plate is disconnected from the contact, and the main circuit of the motor is disconnected. .

Second, start relay

The schematic diagram of the starting relay is shown in the upper left corner of the figure, and consists of an electromagnet mechanism and a contact assembly. The coils are respectively connected to an ignition switch terminal and a ground terminal "E" on the housing, the fixed contact is connected to the starter terminal "S", and the movable contact is connected to the battery terminal "BAT" via the contact arm and the bracket. The starting relay is electrically connected to the normally open contact. When the coil is energized, the relay core generates an electromagnetic force to close the contact, thereby connecting the attracting coil and the holding coil circuit of the relay control.

Third, Dongfeng EQ1090 car starting circuit

The Dongfeng EQ1090 car uses the QD124 type starter, which is an electromagnetically controlled strong meshing starter. It adopts a rolling one-way clutch and the drive gear is 11 teeth. The rated power is 1.5kw. The starting circuit is shown in Figure 10-4. , including the control circuit and the starter main circuit.

Control circuit

The control circuit includes a starter relay control circuit and a starter electromagnetic switch control circuit.

The starting relay control circuit is controlled by an ignition switch, and the controlled object is a relay coil circuit. When the ignition switch start gear is turned on, the current flows from the battery politics through the starter power supply terminal to the ammeter, and after the ignition switch from the ammeter, the relay coil returns to the battery negative. Therefore, the relay core generates a strong electromagnetic attraction, which is a control circuit for closing the relay contact and turning on the electromagnetic switch of the starter.

2. Main circuit

As indicated by the arrow in the figure, after the electromagnetic switch is turned on, the attracting coil 3 and the holding coil 4 generate a strong electromagnetic attraction, and the main circuit of the starter is turned on. The circuit is:

Battery positive → starter power supply terminal → electromagnetic switch → excitation winding → armature winding → grounding → battery negative, so the starter generates electromagnetic torque, start the engine.