All-wheel-drive disconnect clutch control

A method for controlling a vehicle drivetrain, comprising:

• (a)) de-energizing a clutch that connects a source of rotating power through a differential to a wheel;
• (b) determining a reference speed and a reference count;
• (c) when a speed of a differential component is less than the reference speed, rotating said component through a sump by pulsing the clutch;
• (d) while a speed of said component exceeds the reference speed and the count of a timer, started when the clutch is de-energized, exceeds the reference count, pulsing the clutch.

A vehicle drivetrain, comprising:

• a source of rotating power;
• output shafts;
• a differential for transmitting rotating power between the source of rotating power and the output shafts;
• a clutch for alternately de-energizing and energizing a drive connection between the output shaft and a vehicle wheel;
• a controller configured to rotate a differential component through a sump containing lubricant by pulsing the clutch when the clutch is de-energized and a speed of the differential is less than a reference speed, and cyclically pulsing the clutch while a speed of said component exceeds the reference speed and a count of a timer, started after the clutch is de-energized, exceeds a reference count.

A vehicle drivetrain, comprising:

• a source of rotating power;
• a shaft for transmitting rotating power from the source of rotating power;
• a clutch for alternately de-energizing and energizing a drive connection between the shaft and a vehicle wheel;
• a controller configured to rotate a component through a sump containing lubricant by pulsing the clutch when the clutch is de-energized and a speed of the component is less than a reference speed, and to cyclically rotate the component through the sump by pulsing the clutch while a speed of said component exceeds the reference speed and a count of a timer, started after the clutch is de-energized, exceeds a reference count.