Fan clutch for vehicles configured for low engine speed

A system for controlling a fan speed in a vehicle engine comprising:

• a fan capable of rotating between a stationary speed and full speed and continuous variable speeds therebetween;
• a continuously variable, wet clutch assembly for controlling the fan speed including clutch plates selectively positionable between a fully engaged position wherein the fan operates at full speed and a fully released position wherein the fan is stationary and continuously variable positions between fully engaged and released positions, and
• a closed loop electronic control system for controlling the clutch position in response to the fan speed.

A continuously variable wet fan clutch adapted to complement the speed characteristics of an engine operating at low and high engine speeds and speeds between said low and high speeds, the fan clutch comprising in combination:

• a belt drive from the engine to the fan clutch and adapted to overdrive the fan for cooling the engine at low cruising speeds,
• an electronic control system for the fan clutch including means for sensing the fan speed and operating the clutch in response thereto,
• the electronic control system including a processor adapted to respond to engine speed above a predetermined level and to drive the clutch in a continuous slip mode for so long as the engine speed exceeds said predetermined level.

A fan clutch package for use with an engine, in which the engine speed is adapted to cruise in a range of about 1100 rpm or less, yet capable of operating at speeds of about 2500 rpm or more, the engine requiring full cooling capacity for at least intervals when operating at low engine speeds, the fan clutch package comprising, in combination:

• a driver for driving the fan clutch from the engine, and having a ratio of greater than one to over speed the fan, so that the fan operates at full cooling capacity with the engine operating at a speed of about 1100 rpm,
• an electronic control system for the fan clutch having an input for sensing engine speed, the control system sensing the onset of engine speed exceeding a predetermined threshold and adapted to switch the fan clutch into a continuous slip mode for so long as speed exceeds the threshold in order to reduce horsepower expenditure in the fan.