Advanced Secondary Cooling Systems for Light Trucks

Improvements in microprocessor-based electric motor drives have opened up new opportunities for advances in automotive thermal management. For light trucks and SUV's, secondary cooling systems can provide benefits of improved heat rejection, variable temperature control, packaging flexibility, improved warm-up, and reduced primary cooling system power consumption. Of particular attraction are the relatively low power consumption, 12 V operating voltage, and size of the electric drive components. This paper details the design and testing of two separate systems; the first being a controlled transmission cooling/heating system on a 1999 Chevrolet Tahoe; the second being an independent EGR cooling system on a 2004 Ford Excursion. Future drivers for such systems include higher engine horsepower (resulting in higher heat rejection), tighter emissions limits, reduced packaging requirements, increased emphasis on fuel economy, and continued improvement of the electric drive performance/cost ratio.