Fan Drive System.
DEPARTMENT OF THE ARMY WASHINGTON D C
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A variable speed fan drive mechanism for an engine coolant system controlled by temperature and fan speed signals. The mechanism includes a hydrostatic pump-motor unit hydrostatic transmission powered by the engine, for transmitting power to the fan. Mechanical signals related to coolant temperature and fan speed are supplied to a comparator mechanism that delivers a mechanical output control signal. The output control signal is magnified and applied as a control force to vary the displacement of the pump in the hydrostatic unit. The comparator mechanisms has the effect of negating engine speed as a control force. Thus, high engine speeds that would tend to produce unduly large hydraulic flows through the pump-motor circuit are reflected in high fan speed signals fed into the comparator mechanism, which produces a corrected output signal that appropriately reduces pump dislacement to thus reduce the fan speed to low energy consumption levels. Author
- Air Conditioning, Heating, Lighting and Ventilating