Steering angle control of independent rear clutches in a four-wheel drive vehicle

An adaptive drive system for a four-wheel drive vehicle comprising, in combination,

• a primary drive line,
• a secondary driveline having left and right electromagnetic clutches driving a respective pair of left and right axles and wheels,
• an open center differential having a first output driving said primary driveline and a second output driving said secondary driveline,
• a steering angle sensor for providing a signal indicating a position of a steering component, and
• a microprocessor for receiving said signal from said steering angle sensor, providing a dead band and having a pair of outputs controlling a respective one of said pair of electromagnetic clutches, said microprocessor outputs operating outside said dead band to disengage said left clutch on a turn to the left as sensed by said steering angle sensor and disengage said right clutch on a turn to the right as sensed by said steering angle sensor,
• wherein said microprocessor disengages said electromagnetic clutches outside said dead band in proportion to said position of said steering component.

A method of operating an adaptive drive system comprising the steps of:

• providing a front driveline and a rear driveline having a twin clutch axle;
• providing an open center differential for delivering torque to said front and rear drivelines at a predetermined, fixed ratio;
• providing a sensor for generating a signal representing an angular position of a steering component;
• providing a microprocessor for receiving said sensor signal, creating a dead band at a substantially straight ahead position of said steering angle sensor;
• and
• providing an output to each of said twin clutches of said axle to engage said clutches when said steering angle sensor is disposed in said dead band and inhibiting said signal to one of said clutches on an inside of a turn outside said dead in proportion to said position of said steering angle sensor to release said one of said clutches.