All-wheel drive with disconnect system

Abstract

A vehicle drive train for transferring torque to first and second sets of wheels includes a first driveline adapted to transfer torque to the first set of wheels and a first power disconnection device. A second driveline is adapted to transfer torque to the second set of wheels and includes a second power disconnection device. A hypoid gearset is positioned within one of the first driveline and the second driveline in a power path between the first and second power disconnection devices. The hypoid gearset is selectively disconnected from being driven by the first driveline and the second driveline when the first and second power disconnection devices are operated in a disconnected, non-torque transferring, mode. At least one of the first and second disconnection devices includes an active dry friction clutch.

What is claimed is: 
     
         1 . A vehicle drivetrain for transferring drive torque from a powertrain to first and second sets of wheels, the drivetrain comprising:
 a first driveline including a first differential assembly and a power take-off unit, the first differential configured to transfer drive torque from the powertrain to the first set of wheels, the power take-off unit including a first hypoid gearset and a first power disconnection device operable in a connected, torque transferring mode to drivingly connect the first hypoid gearset to the powertrain and operable in a disconnected, non-torque transferring mode to cease the transfer of drive torque from the powertrain to the first hypoid gearset;   a second driveline adapted to transfer drive torque to the second set of wheels and including a second hypoid gearset drivingly coupled to the first hypoid gearset and a second disconnection device operable in a connected, torque transferring mode to drivingly connect the second hypoid gearset to the second set of wheels and operable in a disconnected, non-torque transferring mode to cease the transfer of drive torque from the second hypoid gearset to the second set of wheels; and   wherein the first and second hypoid gearsets are not driven when the first and second disconnection devices are operated in their respective disconnected, non-torque transferring modes, and the power take-off unit includes an input shaft driven by the powertrain and a drive shaft that is coaxial with and rotatable relative to the input shaft and which is configured to drive the first hypoid gearset, wherein the first power disconnection device includes a first clutch having a first clutch member fixed for rotation with the input shaft, a second clutch member fixed for rotation with the drive shaft, and a clutch engagement mechanism for selectively coupling the second clutch member to the first clutch member to establish the connected, torque transferring mode.