Active Stabilizer Bar Systems
DESCRIPTION
BWI Group’s Stabilizer Bar Systems are a family of products that enhance vehicle performance both on-road and off.
BWI Group’s Active Stabilizer Bar System (ASBS) improves on-road 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.
BWI Group’s Stabilizer Bar Disconnect System (SBDS) excels in off-road conditions, improving vehicle wheel articulation for improved traction. Using a rotary actuator mated with an on-board Hydraulic Control Module, the stabilizer bar ends may be de-latched from one another by simply energizing two solenoid valves.
Current production applications use rotary actuators. Linear actuators have also been prototyped.
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TECHNOLOGY
The BWI Group Active Stabilizer 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 BWI Group Active Stabilizer 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.
The BWI Group Stabilizer Bar Disconnect System is a hydraulic system that allows the driver to disconnect (or de-latch) the front stabilizer bar at low vehicle speeds to obtain maximum suspension system articulation for off-road traction. The mechanism for accomplishing this is shown in the accompanying video.
When latched, the sta-bar acts as a traditional anti-roll bar.
PRACTICAL VALUE
Single Channel Hydraulic Control Module
- The front and rear roll torque distribution is fixed
- Aluminum valve block, standalone or integrated into actuator assembly
- Directional and pressure control cartridge valves
- Patented design for fail safe conditions
- Integrated filter and pressure sensor(s), as required
Dual Channel Hydraulic Control Module
- The front and rear roll torque distribution is variable, yielding improved agility and stability
- Use of Antilock Brake System (ABS)-type valves improves weight and cost
- Patented design for continuous pressure controls provides improved response time, on-center control and noise, vibration and harshness (NVH)
- Patented architecture allows up to 50% reduction in hydraulic power requirements enables improved fuel consumption and CO2 emissions
- Patented design for fail safe condition
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TYPES OF SYSTEMS
Rotary Actuator
The BWI Group 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 stabilizer bar stiffness effect, improving off-road performances.
Linear Actuator (Drop Link)
The BWI Group Linear Actuator is an alternative to rotary actuators. It replaces one of the standard passive stabilizer-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
BWI Group has developed a family of Hydraulic Control Modules, satisfying the system requirements for single and dual channel architectures.
