The charging circuit operates when the engine is running. The alternator in the charging circuit produces direct current for the electrical system.
Starting Motor
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| Illustration 1 | g01216877 |
Typical view of a 12 Volt Starting Motor (1) Terminal for connection of the ground cable (2) Terminal 30 for connection of the battery cable (3) Terminal 50 for connection of the ignition switch | |
The starting motor turns the engine flywheel. The rpm is high enough in order to initiate a sustained operation of the fuel ignition in the cylinders.
The starting motor has a solenoid. When the ignition switch is activated, voltage from the electrical system will cause the solenoid to engage the pinion in the flywheel ring gear of the engine. When the pinion gear is engaged in the flywheel ring gear, the electrical contacts in the solenoid close the circuit between the battery and the starting motor.
When the engine begins to run, the overrunning clutch of the pinion drive prevents damage to the armature. Damage to the armature is caused by excessive speeds. The clutch prevents damage by stopping the mechanical connection. However, the pinion will stay meshed with the ring gear until the ignition switch is released. A spring in the overrunning clutch returns the clutch to the rest position.
Alternator
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| Illustration 2 | g00303424 |
(1) Typical view of a shaft for mounting the pulley | |
The alternator produces the following electrical output:
- Three-phase
- Full-wave
- Rectified
The alternator is an electro-mechanical component. The alternator is driven by a drive belt from the crankshaft pulley. The alternator charges the storage battery during the engine operation.
The alternator converts the mechanical energy and the magnetic energy into electrical energy. This conversion is done by rotating a direct current electromagnetic field on the inside of a three-phase stator. The electromagnetic field is generated by electrical current flowing through a rotor. The stator generates AC electrical power.
The alternating current is changed to direct current by a three-phase, full-wave rectifier. Direct current flows to the output terminal of the alternator. The rectifier has three exciter diodes. The direct current is used for the charging process.
A regulator is installed on the rear end of the alternator. Two brushes conduct current through two slip rings. The current then flows to the rotor field. A capacitor protects the rectifier from high voltages.
The alternator is connected to the battery through the ignition switch. Therefore, alternator excitation occurs when the switch is in the ON position.