Rear drive module for all-wheel drive vehicle

An all-wheel drive vehicle comprising:

• an engine;
• a transaxle for transferring drive torque from said engine to a pair of front wheels;
• a power take-off unit for transferring drive torque from said transaxle to a drive shaft;
• a pair of rear wheels driven by first and second axleshafts;
• and
• a drive axle assembly for transferring drive torque from said drive shaft to said first and second axleshafts, said drive axle assembly including a drive case driven by said drive shaft, a first output shaft connected to said first axleshaft, a second output shaft connected to said second axleshaft, a first hydraulic coupling operably installed between said drive case and said first output shaft and including a first multi-plate friction clutch, a first pump operable to pump fluid from a sump to a first pressure chamber in response to speed differentiation between said drive case and said first output shaft, a first piston retained in said first pressure chamber to exert a clutch engagement force on said first friction clutch in proportion to the fluid pressure in said first pressure chamber, and a first control valve mounted to said first piston and having a first valve member moveable from a closed position to an open position when the fluid pressure in said first pressure chamber exceeds a predetermined maximum pressure value for venting fluid to said sump, and a first thermal actuator operable for moving said first valve member from its closed position to its open position when the temperature of the fluid in said sump exceeds a predetermined maximum temperature value, and a second hydraulic coupling operably installed between said drive case and said second output shaft including a second multi-plate friction clutch, a second pump operable to pump fluid from said sump to a second pressure chamber in response to speed differentiation between said drive case and said second output shaft, a second piston retained in said second pressure chamber to exert a clutch engagement force on said second friction clutch in proportion to the fluid pressure in said second pressure chamber, and a second control valve mounted to said second piston and having a valve member moveable from a closed position to an open position when the fluid pressure in said second pressure chamber exceeds a predetermined maximum pressure value for venting fluid to said sump, and a second thermal actuator operable for moving said second valve member from its closed position to its open position when the temperature of the fluid in said sump exceeds a predetermined maximum temperature value.