Patent ID: 6645112
Filing Date: 2003-11-11
Classification: B60K,F16H,Y10T

Abstract:
A transfer case for use in a four-wheel drive vehicle having a powertrain and first and second drivelines, comprising:a first output shaft adapted to transmit drive torque from the powertrain to the first driveline; a second output shaft adapted to transmit drive torque to the second driveline; a differential unit having a first sun gear driven by said first output shaft, a second sun gear driving said second output shaft, planet gears meshed with said first and second sun gears, and a planet carrier rotatably supporting said planet gears; a worm gearset having a worm gear fixed for rotation with said planet carrier, and a worm meshed with said worm gear; a motor operable for driving said worm; and a control system for controlling variable speed actuation of said motor to vary the relative speed between said first output shaft and said planet carrier for controlling the drive torque transmitted from said second sun gear to said second output shaft; wherein a locked four-wheel drive mode is established when said worm gearset is held against rotation, and wherein an on-demand four-wheel drive mode is established for continuously varying the torque transfer ratio between said first and second output shafts when said motor is actuated to vary the rotary speed of said planet carrier relative to said first output shaft.