System Overview

System overview

Active On Demand Coupling




The main role of Active On demand Coupling and the control module for all wheel drive (Differential Electronic Module) is to regulate the all wheel drive function, i.e. the distribution of drive between the front and rear axles. The system consists of a coupling assembly with a mechanical, hydraulic and electronic component. The coupling is located on the rear axle, between the axle gear and the propeller shaft. The mechanical and hydraulic component is driven by the rotation of the propeller shaft.
The Active On Demand Coupling provides the following characteristics:
- Permanent all wheel drive with electronic control of torque transfer
- Driving characteristics similar to all wheel drive
- Fast reaction
- No wind-up forces during low speed maneuvering
- The system is not sensitive to differences between tires (when driving with a spare wheel for example)
- The system is not sensitive to being towed with one axle raised
- The system is not sensitive to brake tests on a chassis dynamometer.

Coupling unit and control module (differential electronic module)




The hydraulic component consists of 1-5, the mechanical component consists of 6-10 and the electronic component consists of 11-14.
1. Pressure valves
2. Accumulator
3. Oil filter
4. Annular pistons
5. Control valves
6. Input shaft
7. Inner and outer wet plates
8. Sinusoidal cam disc
9. Rollers with annular pistons
10. Output shaft
11. Electric oil pump
12. Stepper motor for the control valve
13. Temperature sensor
14. Control module for all wheel drive (differential electronic module).
The differential electronic module is integrated with the coupling unit.
The differential electronic module communicates with other control modules via CAN.
The control module has no internal diagnostics.

Signals
The table below summarizes the input and output signals to and from the differential electronic module. The illustration below displays the same information with the Volvo part numbers.