TRANSFER CASE UTILIZING AN ON-DEMAND CENTRIFUGALLY GOVERNED HYDRAULIC POWER SUPPLY TO PERFORM BOTH RANGE SHIFT AND ON-DEMAND FOUR WHEEL DRIVE

摘要

A control system (100) for an all-wheel-drive torque transfer case (102) coupling of a motor vehicle (104) including a power unit (130) having a centrifugally governed fluid pump (132) and a flow valve (134) movable between recirculation and diverter positions (134a, 134b). A control valve (136) located between the fluid pump (132), the all-wheel-drive clutch assembly (112), and the range shift assembly (120). The control valve (136) operable between a first position (136a) allowing fluid flow between the pump (132) and the clutch assembly (112), and a second position (136b) allowing fluid flow between the pump (132) and the range shift assembly (120). At least one range shift valve (138; 152, 154) located between the control valve (136) and the range shift assembly (120). The at least one range shift valve (138; 152, 154) operable between a range shift exhaust mode (138a; 136a, 152a, 154a), a high range mode (138b; 136b, 152b, 154a), a locked range mode (138c; 136a, 152b, 154b), and a low range mode (138d; 136b, 152a, 154b) of operation by selectively allowing and/or preventing pressurized fluid flow to/from the first and second expandable fluid chambers (126, 128) of the range shift assembly (120).