Transfer case with hydraulic range shift and adaptive clutch control

Abstract

A power transfer system for a motor vehicle is disclosed to include a transfer case having a clutch assembly arranged to control speed differentiation and torque biasing across an interaxle differential, a hydraulic clutch actuation system operable to control actuation of the clutch assembly, sensors for detecting and generating sensor signals indicative of various dynamic and operational characteristics of the vehicle, and a controller for controlling the hydraulic clutch actuation system in response to the sensor signals. Upon the occurrence of traction loss, the clutch assembly is automatically actuated for limiting interaxle slip while transferring increased drive torque to the non-slipping driveline. Under a preferred control scheme, the actuated condition of the clutch assembly is controllably modulated between its non-actuated and fully-actuated limits for automatically varying the magnitude of speed differentiation and torque biasing across the interaxle differential in response to changes in the operational characteristics of the motor vehicle. As a further feature of the present invention, the transfer case can be equipped with a gearset and a hydraulically-actuated range shift mechanism for permitting on-the-move shifting between high-range and low-range drive modes.