Borgwarner Inc.

John R Ficht

Gary A Oliveira

Richard Thomas Fosmoe

The present invention is directed toward a method to digitally control a transfer case through a digital data bus to provide synchronized low to high shift capabilities in vehicles that employ a controller area network (CAN) system. In addition, a transfer case that can be digitally controlled in a vehicle with a controller area network (CAN) system to provide synchronized low to high shifts is also disclosed.

Method and apparatus for providing synchronization of low to high shifts in a transfer case

A transfer case includes an input shaft, an output shaft, and a gear set selectively operable to translate torque between the input and output shafts at reduced speeds. A clutch is operable to translate torque between the input and output shafts either directly or through the gear set. An actuator, having a rotational output, is operatively coupled to the clutch for moving the clutch between predetermined positions. A control unit is employed in connection with the transfer case to effect the method of synchronizing low to high shifts in the transfer case. To this end, the control unit calculates the speed of the actuator as it moves the clutch to a neutral position. The control unit further determines the additional time until the clutch will reach a predetermined synchronization point using the speed of the actuator and the remaining rotational distance through which the actuator must move for the clutch to reach the predetermined synchronization point. The control unit is further operable to stop the actuator when the clutch has reached the synchronization point for no longer than a predetermined time. The control unit then senses and compares the rotational speeds of the input and output shafts and signals the actuator to complete the shift from low to high by moving the clutch to provide direct torque translation between the input and output shafts when the difference in the rotational speeds of the input and output shafts is less than a predetermined value.

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Wales, MI, United States of America

John R Ficht