BWIGroup, Active Stabiliser Bar Systems are a family of products that improve vehicle comfort and handling, especially during cornering maneuvers. When the vehicle is cornering, lateral acceleration is measured and the anti-roll torque required to keep the vehicle flat and stable is calculated. The Electronic Control Unit (ECU) determines the magnitude and direction of the hydraulic pressure and provides signals to the Hydraulic Control Module (HCM). Hydraulic power is provided by an engine or electric motor driven hydraulic pump. The HCM regulates the pressure in the actuators. The hydraulic actuators are used to provide a force that counteracts the roll moment induced by the lateral acceleration, thus reducing vehicle roll angle.

The BWIGroup Active Stabiliser Bar System allows a drastic reduction of vehicle roll while cornering. The roll angle reduction improves both the driver and passengers’ comfort. It also improves the vehicle steering feel, agility and stability.

Further improvements can be reached with Dual Channel Systems by adapting the front / rear roll torque distribution depending on the driving conditions. For example, the anti-roll torque can be applied on the rear axle of a front-wheel driven vehicle when accelerating in a curve in order to limit its under-steer characteristic.

Because the BWIGroup Active Stabiliser Bar System is relying on a hydraulic anti-roll torque, it translates into a reduction of the overall vehicle roll stiffness. Therefore vehicle isolation is not degraded. Furthermore, anti-roll torque can be applied to counter-act body oscillations when the vehicle is driven over low frequency road inputs. This results in improved comfort.

Rotary Actuator
The BWIGroup Rotary Actuator is based on a ball screw principle, allowing for high stabilizer bar torques from 900 Nm up to 1500 Nm at 180 bar working pressure. It is incorporated within two half torsion bars, replacing the standard vehicle anti-roll bar. This type of installation allows full suspension travel with no stabiliser bar stiffness effect, improving off-road performances.

Linear Actuator (Drop Link)
The BWIGroup Linear Actuator is an alternative to rotary actuators. It replaces one of the standard passive stabiliser-bar drop links. Although the free wheel displacement is limited compared to a rotary actuator, it is possible to reach high system on-road performances at reduced mass and costs.

Hydraulic Control Modules
BWIGroup has developed a family of Hydraulic Control Modules, satisfying the system requirements for single and dual channel architectures:

Single Channel Hydraulic Control Module

• The front and rear roll torque distribution is fixed
• Aluminum valve block
• Directional and pressure control cartridge calves
• BWIGroup patented design for fail safe conditions
• Integrated filter and pressure sensor

Dual Channel Hydraulic Control Module

• The front and rear roll torque distribution is variable=improved agility and stability
• Use of ABS type valves improves weight and cost
• BWIGroup patented design for continuous pressure controls = Improved response time, on-centre control and NVH
• BWIGroup patented architecture allowing up to 50% reduction in hydraulic power requirements equals improved fuel consumption and CO2 emissions and requirements
• BWIGroup patented design for fail safe condition