Temperature sensing fan drive with fluid coupling

A fan drive comprising:

• a fan housing rotatably supported on a drive shaft so as to be relatively rotatable with respect thereto;
• a partition plate dividing an internal space of the fan housing into a working-fluid reservoir chamber and a working chamber;
• a first communication port formed in the partition plate to communicate the working-fluid reservoir chamber with the working chamber;
• a second communication port formed in the partition plate to communicate the working-fluid reservoir chamber with the working chamber;
• a rotor fixedly connected to the drive shaft;
• a torque-transmitting viscous-coupling portion operatively disposed between the rotor and the fan housing to transmit torque from the rotor to the fan housing via the working fluid;
• a first valve mechanism which adjusts an opening of the first communication port in response to an atmospheric temperature in a circumference of the fan housing;
• and
• a second valve mechanism which adjusts an opening of the second communication port in response to a sensed energy level indicative parameter.

A control apparatus for a fan drive which cools an engine cooling-system radiator and an air-conditioner condenser disposed in front of the cooling-system radiator, the fan drive having a fan housing rotatably supported on a motor driven drive shaft, a partition plate dividing an internal space of the fan housing into a working-fluid reservoir chamber and a working chamber, a rotor fixedly connected to the drive shaft and a torque-transmitting viscous-coupling operatively disposed between the rotor and the fan housing to transmit torque from the rotor to the fan housing via the working fluid, the control apparatus comprising:

• a first communication port formed in the partition plate to communicate the working-fluid reservoir chamber with the working chamber;
• a second communication port formed in the partition plate and different from the first communication port to communicate the working-fluid reservoir chamber with the working chamber:
• a duplex valve system including a first valve mechanism having a first valve portion which adjusts an opening of the first communication port, and a second valve mechanism having a second valve portion which adjusts an opening of the second communication port;
• a temperature-sensing bimetallic coil fixedly connected at one end to the fan housing and mechanically linked at the other end to the first valve mechanism for adjusting the opening of the first communication port in response to an atmospheric temperature proximate the fan housing;
• a pressure sensor which monitors a refrigerant pressure in the air-conditioner condenser to generate a refrigerant pressure sensor signal;
• a fan-drive controller electronically connected to the refrigerant pressure sensor to receive the refrigerant pressure sensor signal and to generate a control signal when a value of the refrigerant pressure sensor signal exceeds a predetermined threshold value;
• and
• an actuator associated with the second valve mechanism which is responsive to the control signal from the fan-drive controller to shift the second valve mechanism from a fully-closed position to a full-open position.