Patent ID: 6780132
Filing Date: 2004-08-24
Classification: B60K,Y10T

Abstract:
A transfer case for use in motor vehicles for transferring drive torque from a powertrain to first and second drivelines, said transfer case comprising:a first output shaft, connected to the powertrain of the vehicle and 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 transfer clutch adapted to selectively transfer drive torque from said first output shaft to said second output shaft; and a ball screw assembly adapted to actuate said transfer clutch, said ball screw assembly including a hollow ball screw mounted within said transfer case, about said first output shaft, and including an outer surface having an outwardly facing helical channel formed therein, a hollow ball nut extending circumferentially around said ball screw and including an inner surface having an inwardly facing helical channel formed therein, a ball channel defined by said inwardly facing helical channel and said outwardly facing helical channel, a plurality of ball bearings positioned within said ball channel, thereby coupling said ball screw and said ball nut such that rotational movement of said ball screw and said ball nut relative to one another is translated into axial movement of said ball nut and said ball screw relative to one another; and an electric motor, having a stator and a rotor, adapted to engage said ball nut to rotationally move said ball nut relative to said ball screw; said motor further including a planetary gear set having a ring gear, a sun gear and a plurality of planet gears secured within a planetary carrier between and interconnecting said ring gear and said sun gear, said ring gear being attached to said stator, and said sun gear being attached to said rotor; said ball screw being rotatably and axially fixed within said transfer case and said ball nut being rotatably and axially moveable relative to said transfer case, said motor engaging said ball nut such that when said motor is activated said ball nut rotates relative to said ball screw and said transfer case, thereby moving said ball nut axially relative to said transfer case such that said ball nut applies an axial force to said clutch packs, thereby rotationally connecting said first and second clutch members and rotationally connecting said first and second output shafts.