GKN Touts Ultra-Compact AWD Disconnect

GKN Driveline says its new all-wheel-drive disconnect system for small cars is the industry's lightest and most compact.

The unit automatically decouples the powertrain aft of the driven front wheels under road conditions at times when also powering the rear wheels isn't necessary. GKN says the configuration can improve steady-state fuel economy as much as 4% compared to a drivetrain with fulltime AWD.

The system consists of a monoblock housing containing a power transfer unit linked to the transmission's final drive differential. Also inside is a fast-disconnect device and brake. Some system components are variants of those already in use in the Range Rover Evoque SUV's GKN-developed all-wheel drive disconnect unit.

The system engages or disengages the driveshaft at the transmission. A companion clutch at the other end of the driveshaft does the same with the all-wheel-drive components downstream of the differential's hypoid gears. The effect is to stop driveline components from rotating unnecessarily.

The new GKN system includes a fulltime control unit that monitors vehicle dynamics. When road conditions or the driver needs more traction, the technology can reconnect the engine and rear wheels within 300 milliseconds, according to the company.

The technology's active torque biasing feature adjusts automatically to driving conditions. GKN says the system can be tweaked to permit torque vectoring between individual rear wheels.