Electronic function

Fig 1: Active On Demand Coupling Electronic Function

Courtesy of VOLVO CARS OF NORTH AMERICA.

1. Oil pressure and temperature sensor
2. Differential electronic module (DEM)
3. Control valve/axial solenoid
4. Electrical feed pump.

The differential electronic module (DEM) is secured directly to the coupling unit and forms a single unit with the axial solenoid and control valve. The differential electronic module (DEM) receives signals from the engine control module (ECM) and the brake control module (BCM) via the control area network (CAN). The differential electronic module (DEM) uses the sensor signals to control the oil pressure to the multi-plate clutch by adjusting the axial solenoid. The axial solenoid regulates the control valve constantly using a pulse width modulation (PWM) signal. The oil pressure for the multi-plate clutch determines the amount of torque which can be transferred to the rear wheels.

Active On demand Coupling (AOC) has an oil pressure and temperature sensor, which gauge the prevailing temperature and pressure of the hydraulic fluid. The oil pressure and temperature sensor provide the differential electronic module (DEM) with information about the temperature and pressure. Four wheel drive is disengaged to protect the coupling unit from damage if the temperature becomes too high, above 97 °C. The coupling unit is re-engaged at full function when the temperature falls below 93 °C.