Patent ID: 7395891

Claim:
A method for regulating driving torque transfer through a friction clutch in a torque transfer case for a powertrain for a four-wheel drive vehicle; the powertrain including an engine, a geared transmission between the engine and the torque transfer case; an engine controller and a powertrain controller; a primary axle driveshaft connected driveably to torque output elements of the torque transfer case and a secondary axle driveshaft connected to torque output elements of the torque transfer case through the friction clutch; the method comprising: engaging the friction clutch to effect power transfer from the engine to the secondary axle driveshaft as engine power is delivered to the primary axle driveshaft; determining whether driving friction elements of the friction clutch are slipping; and reducing engine torque request in incremental steps until slipping of the driving friction elements of the friction clutch is eliminated.