Abstract: Clutch control systems for a power take-off system of a vehicle, such as those employing all-wheel and four-wheel drive systems. The control system calculates the temperature of the clutch system, based on one or more vehicle operational parameters. If the clutch system reaches a pre-determined temperature limit, the control system selectively stops the operation of the clutch system until the clutch temperature drops below the pre-determined temperature limit. The control system includes an electronic control unit, e.g., a computer or microprocessor, that calculates and/or processes one or more vehicle operational parameters, including, but not limited to: (1) clutch input and output speeds; (2) slip across the clutch; (3) clutch torque; (4) current clutch power; (5) accumulated clutch power; (6) temperature delta (i.e., change) of the clutch; and (7) clutch temperature.

Abstract: A method of detecting the presence of an undersized, e.g., mini-spare, or an underinflated, oversized or overinflated tire or tires on a passenger motor vehicle improves operation of traction control, stability and anti-lock brake systems by compensating for such operating anomalies. The method includes the steps of sensing the steering angle, sensing the actual rotational speeds of each wheel, determining the actual vehicle speed, calculating each expected wheel speed based upon the sensed steering angle and wheel speeds, calculating each tire diameter based upon the calculated wheel speeds and, finally, determining whether such diameters are within various defined ranges which permit normal operation, permit reduced function operation, or require system shut down.

Abstract: Engagement characteristics of electromagnetic friction clutch pack assemblies disposed in, for example, motor vehicle transfer cases are improved, especially at the transition between static and dynamic friction modes, by superimposing a random noise signal on an otherwise smooth analog or stepped digital signal. The controller and driver for the clutch includes a random noise (signal) generator having an output which is superimposed on the controller output generated in response to signals from various sensors disposed on the vehicle. When the controller inputs cause clutch engagement in accordance with the controller software, an engagement signal comprising both a drive portion and a smaller random noise portion is supplied to the electromagnetic clutch operator. Improved, less perceptible clutch engagement action is thereby achieved.

Abstract: A method and apparatus for operating a power transfer device such as a vehicle transfer case having, shaft speed sensors, a two speed (high-low) drive assembly, an electrically, pneumatically or hydraulically operated shift operator and a microprocessor comprising the steps of sensing the speeds of the transfer case input shaft and output shaft, calculating the rate of change (.DELTA.S/.DELTA.t) of the speed of the input shaft, predicting, based upon such rate of change, a time when the input shaft and the output shaft will be synchronized and commencing movement of such shift operator at a time prior to such synchronization in order to effect engagement of such clutch into high gear at substantially the instant of synchronization.