Fuel-fired furnace with self-cooling draft inducer fan

摘要

A gas-fired forced draft air heating furnace is provided with a specially designed self-cooling draft inducer fan that overlies an inshot-type burner section of the furnace and is operatively supported on a heat exchanger plenum portion of the furnace housing. The fan motor is supported on an outboard housing side of the fan, and an umbrella cooling fan is coaxially secured to an outboard end of the fan drive shaft. During operation of the draft inducer fan, the umbrella fan is rotationally driven to direct a flow of ambient cooling air toward the outboard side of the draft inducer fan housing in a manner causing the air flow to sequentially contact and cool the outer shaft end bearing area, the motor windings and the inner shaft end bearing area at the outer side of the draft inducer fan housing. A baffle structure mounted on the outer draft inducer fan housing side serves to guide the cooling air flow along the inner shaft end bearing area and shield the burner flames from disruption by the cooling air flow area after it contacts the inner shaft end bearing area.