Vehicle moving and turning left (Front suspension)

Vehicle moving and turning left

When the vehicle is turning left, the accelerometers detect the cornering forces applied and transmit signals to the ECU. The ECU determines that an opposing force must be applied to the torsion bars to counter the cornering forces. The ECU supplies a current to the solenoid of the DCV2. Simultaneously, a current is sent from the ECU to the pressure control valve which operates to restrict the flow of fluid returning to the reservoir.

The restriction causes the hydraulic pressure in the system to rise and the pressure is sensed by the pressure transducer which sends a signal to the ECU. The ECU determines from the inputs it receives what pressure is required and adjusts the pressure control valve accordingly.

The pressure in the system is applied to the annulus of each actuator, applying an opposing force to the torsion bar and minimising the cornering effect on the vehicle and maintaining the vehicle attitude. The fluid displaced from the full area of the actuator is returned to the reservoir via the valve block.

As the cornering force is removed when the vehicle straightens up, the ECU opens the pressure control valve to reduce the pressure in the system. The fluid bleeds from the actuator back into the system as the cornering force is reduced, removing the force from the torsion bar. When the vehicle is moving in a straight line DCV 2 closes.

Vehicle moving and turning right

When the vehicle is turning right, the accelerometers detect the cornering forces applied and transmit signals to the ECU. The ECU determines that an opposing force must be applied to the torsion bars to counter the cornering forces. The ECU supplies a current to the solenoid of the DCV1. Simultaneously, a current is sent from the ECU to the pressure control valve which operates to restrict the flow of fluid through the by-pass gallery.

The restriction causes the hydraulic pressure in the system to rise and the pressure is sensed by the pressure transducer which sends a signal corresponding to the pressure to the ECU. The ECU determines from the inputs it receives what pressure is required and adjusts the pressure control valve accordingly.

The pressure in the system is applied to the full area of each actuator, applying an opposing force to the torsion bar and minimising the cornering effect on the vehicle and maintaining the vehicle attitude. The fluid displaced from the annulus of the actuator is returned to the reservoir via the valve block.

As the cornering force is removed when the vehicle straightens up, the ECU opens the pressure control valve to reduce the pressure in the system. The fluid bleeds from the actuator back into the system as the cornering force is reduced, removing the force from the torsion bar. When the vehicle is moving in a straight line the DCV 1 closes.

Vehicle moving in a straight line

The ECU is constantly monitoring the signals received from the accelerometers and operates the DCV's and pressure control valve to maintain the vehicle attitude when the vehicle is moving.

Off-road driving

Off-road detection is achieved by the ECU by monitoring the signals from the upper and lower accelerometers for varying degrees of body movement. Off-road driving generates differing signals to the accelerometers which in turn produce differing outputs due to their vertical separation and the location of the roll centre of the vehicle. The two signals are passed through a filter to remove any offset caused by the vehicle leaning or the terrain. The ECU then uses this signal to calculate the percentage of road roughness.

Below 25 mph (40 km/h) the percentage of road roughness calculated is used by the ECU to limit the operation of the ACE system. The system is completely inoperative at speeds below 2 mph (3 km/h). At speeds above 25 mph (40 km/h) the system disables the percentage road roughness signal and full ACE system assistance is restored.

Side slope detection

The ECU uses side slope detection when the upper and lower accelerometers detect an average acceleration of more than ± 0.2 g and a road speed of less than 25 mph (40 km/h).

When side slope is detected both DCV's close to provide a 'locked bars' condition. This condition increases stability and gives a consistent vehicle response. As the road speed increases up to 25 mph (40 km/h), the level of average lateral acceleration must also increase and be maintained for the system to recognise that the vehicle is on a side slope. If the side slope angle is steep and the road speed is low, the ECU will detect the side slope in a short time.