Patent ID: 8888658

Claim:
In a fluid flow control system ( 100 ) for an all-wheel-drive torque transfer case ( 102 ) coupling for a motor vehicle ( 104 ), the improvement comprising: a fluid pressure actuated on-demand all-wheel-drive clutch assembly ( 112 ) having a spring ( 114 ) biasing a piston ( 116 ) to define a single expandable working fluid chamber ( 118 ); a fluid pressure actuated range shift assembly ( 120 ) having a reciprocal member ( 122 ) enclosed within a housing ( 124 ) to define first and second expandable working fluid chambers ( 126 , 128 ): a power unit ( 130 ) having a centrifugal fluid pump ( 132 ) and a flow valve ( 134 ) movable between a recirculation position ( 134 a ) and a diverter position ( 134 b ); a control valve ( 136 ) located between the fluid pump ( 132 ), the clutch assembly ( 112 ), and the range shift assembly ( 120 ), the control valve ( 136 ) operable between a first position ( 136 a ) allowing fluid flow between the pump ( 132 ) and the clutch assembly ( 112 ), and a second position ( 136 b ) allowing fluid flow between the pump ( 132 ) and the range shift assembly ( 120 ); and a range shift valve assembly ( 138 ) located between the control valve ( 136 ) and the range shift assembly ( 120 ), the range shift valve assembly ( 120 ) operable between an exhaust mode ( 138 a ) of operation allowing fluid flow between the first and second expandable working fluid chambers ( 126 , 128 ) and a fluid sump ( 140 ) while preventing fluid flow between the control valve ( 136 ) and the range shift assembly ( 112 ), a high range mode ( 138 b ) of operation allowing fluid flow between the control valve ( 136 ) and the first expandable working fluid chamber ( 126 ) while permitting fluid flow between the second expandable chamber ( 128 ) and the fluid sump ( 140 ), a locked range mode ( 138 c ) of operation preventing fluid flow between the control valve ( 136 ) and the range shift assembly ( 112 ) and preventing fluid flow between the first and second expandable working fluid chambers ( 126 , 128 ) and the fluid sump ( 140 ), and a low range mode ( 138 d ) of operation allowing fluid flow between the control valve ( 136 ) and the second expandable working fluid chamber ( 128 ) while permitting fluid flow between the first expandable working fluid chamber ( 126 ) and the fluid sump ( 140 ).