Freewheel
Some alternators are fitted with freewheels between the rotor shaft and the pulley. However, it is possible to see that the pulley is fitted with freewheels from the cover fitted over the pulley's nut in the center. The freewheels allow the alternator's rotor shaft to rotate freely in one direction. This keeps any jerking in the belt transmission to a minimum. For engine B8444S, the alternator is not fitted with freewheels.
Scheme 571
The above illustrations depict the two different types of connections for the alternator's regulator.
Output voltage from the generator (GEN) is calculated from the calculated battery temperature in order to charge the battery fully. The central electronic module (CEM) calculates the battery temperature using the outside temperature. The outside temperature is obtained from the outside temperature sensor.
See also VIDA Design and Function, Engine control module (ECM).
The Rear electronic module (REM) checks the voltage on the battery and transmits the value out on the CAN network. The value is used in the Central electronic module (CEM), among others, for diagnosing the charging function.
When the ignition key is in position II (or III), the central electronic module (CEM) sends information to the charge regulator (also known as the alternator control module (ACM)) either directly or via the engine control module (ECM).
The regulator directs current to the excitation winding rotor and is then grounded via the regulator. When the current travels through the rotor a magnetic field is formed around the rotor. When the engine is started and the rotor begins to rotate, the magnetic field also rotates and then produces alternating current in the stator windings.
Alternating current is rectified when it passes the diodes and is then fed to the electrical system of the vehicle. The voltage obtained from the stator winding also passes to the regulator via the rectifier and affects the control functions.
The desired charge voltage (desired value), based on factors such as calculated battery temperature, is sent from the central electronic module (CEM) to the charge regulator either directly or via the engine control module (ECM). The regulator then controls so that the desired voltage is obtained by the battery.
The charge indicator lamp in the combined instrument panel is controlled by the driver information module (DIM) via signals from the controller area network (CAN).