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.

1 . (canceled) 
     
     
         2 . A vehicle drivetrain for transferring drive torque from a power source to first and second sets of wheels, the drivetrain comprising:
 a first driveline adapted to transfer drive torque to the first set of wheels and including a power take-off unit and a first power disconnection device, the power take-off unit including an input shaft driven by the power source, a drive shaft positioned coaxial with and surrounding the input shaft along at least a majority of the length of the drive shaft, and a first hypoid gearset drivingly connected to the drive shaft, the first power disconnection device being configured as a first clutch operable in a connected, torque transferring mode to drivingly connect the first hypoid gearset to the input shaft and operable in a disconnected, non-torque transferring mode to disconnect the first hypoid gearset from the input shaft, the 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 coaxial with the input 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; and   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 power 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,   wherein the first and second hypoid gearsets are not driven when the first and second power disconnection devices are operated in their respective disconnected, non-torque transferring modes.   
     
     
         3 . The drivetrain of  claim 2 , wherein the second power disconnection device includes a second clutch configured as an adaptively-controlled multi-plate friction clutch. 
     
     
         4 . The drivetrain of  claim 3 , wherein the first driveline further includes a first differential gearset having a first differential input driven by the power source and drivingly connected to the input shaft, and a pair of first differential outputs driving the first set of wheels. 
     
     
         5 . The drivetrain of  claim 4 , wherein the second driveline further includes a second differential gearset having a second differential input driven by the second hypoid gearset, and a pair of second differential outputs driving the second set of wheels, and wherein the second clutch is operably disposed between one of the second differential outputs and a corresponding one of the second set of wheels. 
     
     
         6 . The drivetrain of  claim 5 , wherein the second driveline further includes a third power disconnection device configured as a third clutch operably located between the other one of the second differential outputs and the corresponding other one of the second set of wheels. 
     
     
         7 . The drivetrain of  claim 6 , wherein the third clutch is configured as an adaptively-controlled multi-plate clutch. 
     
     
         8 . The drivetrain of  claim 4 , wherein a pair of first axleshafts drivingly interconnect the first differential outputs to the first set of wheels, and wherein the input shaft surrounds one of the first axleshafts. 
     
     
         9 . A vehicle drivetrain for transferring drive torque from a power source to first and second sets of wheels, the drivetrain comprising:
 a first driveline including a first differential unit, a power take-off unit, and a first power disconnection device, the first differential unit adapted to transmit drive torque from the power source to the first set of wheels, the power take-off unit including an input shaft driven by the power source, a drive shaft positioned coaxial with and surrounding the input shaft along at least a majority of the length of the drive shaft, and a first hypoid gearset drivingly connected to the drive shaft, the first power disconnection device configured as a first clutch operable in a connected, torque transferring mode to drivingly couple the drive shaft to the input shaft for transferring drive torque to the first hypoid gearset and operable in a disconnected, non-torque transferring mode to uncouple the drive shaft from the input shaft and cease the transfer of drive torque to the first hypoid gearset; and   a second driveline including a second hypoid gearset, a propeller shaft interconnecting the first hypoid gearset to the second gearset, a pair of axleshafts connected to the second set of wheels, and second and third power disconnection devices, the second power disconnection device configured as a second clutch operable in a connected, torque transmitting mode to transfer drive torque from the second hypoid gearset to a first one of the pair of axleshafts and in a disconnected, non-torque transmitting mode to cease the transfer of drive torque from the second hypoid gearset to the first one of the pair of axleshafts, the third power disconnection device configured as a third clutch operable in a connected, torque transmitting mode to transfer drive torque from the second hypoid gearset to a second one of the pair of axleshafts and in a disconnected, non-torque transmitting mode to cease the transfer of drive torque from the second hypoid gearset to the second one of the pair of axleshafts,   wherein the second and third clutches are multi-plate friction clutches, and wherein the first and second hypoid gearsets are not driven when the first clutch is in its disconnected, non-torque transferring mode and the second and third clutches are operated in their respective disconnected, non-torque transmitting modes.   
     
     
         10 . The drivetrain of  claim 9 , wherein the second driveline further comprises a second differential unit operably disposed between the second hypoid gearset and the first and second axleshafts. 
     
     
         11 . The drivetrain of  claim 10 , wherein the second differential unit includes a differential input driven by the second hypoid gearset, a first differential output coupled to the first axleshaft, and a second differential output coupled to the second axleshaft, wherein the second clutch is operably disposed between the differential input and the first axleshaft, and wherein the third clutch is operably disposed between the differential input and the second axleshaft. 
     
     
         12 . The drivetrain of  claim 11 , wherein a control system controls independent operation of the first, second and third clutches. 
     
     
         13 . The drivetrain of  claim 9 , wherein the second hypoid gearset is connected for common rotation with a carrier, wherein the second clutch is disposed between the carrier and the first axleshaft and the third clutch is disposed between the carrier and the second axleshaft, and wherein the second and third clutches are operable in their respective disconnected, non-torque transmitting modes to cease transfer of drive torque from the second hypoid gearset to their respective axleshafts. 
     
     
         14 . The drivetrain of  claim 13 , wherein a control system controls independent operation of the first, second and third clutches. 
     
     
         15 . A vehicle drivetrain for transferring drive torque from a source of power to first and second sets of wheels, the drivetrain comprising:
 a first driveline adapted to transfer drive torque to the first set of wheels and including a power take-off unit, the power take-off unit including an input shaft driven by the power source, a first hypoid gearset, a first power disconnection device operable in a connected, torque transferring mode to drivingly connect the first hypoid gearset to the power source and operable in a disconnected, non-torque transferring mode to cease the transfer of drive torque from the power source to the first hypoid gearset, and a drive shaft drivingly connected to the first hypoid gearset and rotatable relative to the input shaft and positioned coaxial with and about the input shaft along at least a majority of the length of the drive shaft, the first power disconnection device including 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; and   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,   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.   
     
     
         16 . A vehicle drivetrain for transferring torque from a power source to a first pair and a second pair of wheels, the drivetrain comprising:
 a first power transmission device adapted to transfer torque from the power source to the first pair of wheels, the first power transmission device including a first power disconnection device selectively ceasing the transfer of torque to a first hypoid gearset and an input shaft driven by the power source, wherein the first power disconnection device includes a first clutch member fixed for rotation with the input shaft, a drive shaft fixed for rotation with the first hypoid gearset and rotatable relative to the input shaft, a second clutch member fixed for rotation with the drive shaft and coaxial with the input shaft, and a clutch actuation mechanism for selectively coupling the second clutch member for rotation with the first clutch member; and   a second power transmission device adapted to receive torque from the first power transmission device, the second power transmission device transferring torque to the second pair of wheels via a second hypoid gearset rotatably connected to the first hypoid gearset via a propeller shaft and including a second power disconnection device selectively interrupting the transfer of torque from the second hypoid gearset to one of the second wheels, and a third power disconnection device selectively interrupting the transfer of torque from the second hypoid gearset to the other of the second wheels,   wherein one of wheels of the second pair of wheels is connected to a first axleshaft and wherein the other of the wheels of the second pair of wheels is rotatably connected to a second axleshaft;   wherein the second power disconnection device includes a first multi-plate clutch disposed between the first axleshaft and the second hypoid gearset and a first actuator operable to vary an actuation force applied to the first multi-plate clutch to regulate the drive torque transferred from the second hypoid gearset to the first axleshaft,   wherein the third power disconnection device includes a second multi-plate clutch disposed between the second axleshaft and the second hypoid gearset and a second actuator operable to vary an actuation force applied to the second multi-plate clutch to regulate the drive torque transferred from the second hypoid gearset to the second axleshaft.