Principle of Operation

Principle of Operation

Dynamic Drive System Pre-drive Procedure




When the ignition is switched "ON", the ARS control module self test is first performed. The electrical valve functions are conducted to detect short/open circuits in the valve solenoid coils, connectors and harness. The sensors are checked for short/open circuits in the harness, connectors or the internal electronics.

Finally, the hydraulic safety Junctions are checked before the vehicle moves as part of the "Pre-drive Check".

A test pressure (<60 bar) is set between the pump and the failsafe valve. This allows the ARS control module to check if the failsafe valve is actually in the de-energized failshaft position. When in this position, the system pressure is decreased (circulating).

When the failsafe valve is energized (FS as shown to the right) by the ARS control module, the front axle hydraulic circuit is open providing pressure to the oscillating motor (SMV).

The front axle pressure control valve function is tested simultaneously. If pressure does not build up at the front axle stabilizer bar, the Predrive Check criteria will not be met.

The Dynamic Drive function is deactivated when the vehicle is stationary (inertia is not present) and all the valves are de-energized. This also applies when the vehicle is at a standstill on an incline (one sided load). Even though the lateral acceleration sensor provides a signal, the vehicle speed signal is not present.

When the vehicle speed is >15 km/h, the ARS function is started.

Straight Ahead Driving

When the engine is running, the tandem pump supplies hydraulic fluid to the system at a pressure of 3 to 5 bar. The front and rear axle stabilizer bar pressure valves are de-energized (open) and pressure is not applied to the oscillating motors. The hydraulic fluid circulates directly back to the reservoir for as long as the vehicle is driven straight ahead.

Cornering

When cornering, the signals from the lateral acceleration sensor are conveyed to the ARS control module. The control module outputs a pulse width modulated signal (PWM) to the front and rear axle stabilizer bar pressure valve5. The stronger the lateral acceleration, the greater the signal (current flow). The increasing valve current will progressively close the valves forming a higher pressure in the stabilizer bar oscillating motors.

The pressure sensors provide the ARS control module with the stabilizer bar oscillating motor pressures. To direct the buildup pressure according to the corner (left hand or right hand twist), the directional valve is actuated by the control module. The SSE sensor detects the directional valve selector position.

Restricted Function




The system reverts to failsafe mode when a fault is detected. The control module stores the fault and indicates failsafe mode in the instrument cluster. The failsafe situation is shown to the right in the hydraulic overview diagram.

In the event of system failure, the failsafe valve (FS) is de-energized and sprung closed. The hydraulic fluid in the front stabilizer bar is sealed in, ensuring the stability and understeer effect of a conventional stabilizer bar.

The check valves (RW1, RW2) allow the hydraulic fluid to be drawn from the reservoir preventing cavitation in the oscillating motor when the vehicle is driven straight.

External Leakage

External leakage is detected by the front or rear pressure sensors and the ARS control module will deactivate Dynamic Drive (system failure).