Ford Motor Company Limited

Karl Victor Perttunen

Patrick William Gibson

A four-wheel drive vehicle includes a transfer case for controlling the delivery of power between the front and rear wheels of the vehicle. A clutch in the transfer case controls the amount of power delivered to the front and rear wheels in response to a clutch PulseWidth Modulated (PWM) signal which is generated by an electronic powertrain controller. The powertrain controller receives a first signal which is indicative of the rotational speed of a front driveshaft, which transfers motive power from the transfer case to a pair of front wheels, and a second signal which is indicative of the rotational speed of a rear driveshaft, which transfers motive power from the transfer case to a pair of rear wheels. The powertrain controller compensates for wheels which have a different effective diameter by determining the difference between the first signal and the second signal, filtering the difference to remove low frequency components, and generating the clutch PWM signal as a function of the high frequency components.

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W. Bloomfield, MI, United States of America

Karl Victor Perttunen