GB330967A - Improvements in or relating to the ventilation of dynamo electric machines - Google Patents

Abstract

330,967. General Electric Co., Ltd., and Orsettich, R. March 20, 1929. Dynamos and motors, armatures and field magnets, cooling and ventilating. - The fan of a dynamo-electric machine, particularly one in which the ratio of the rotor diameter to that of the shaft is relatively small, is of the aeroplane propeller type, i.e. the type in which the angle between a plane perpendicular to the axis of rotation bf the fan and planes passing through the leading edge and the trailing edge of a blade and parallel to the length thereof decreases from the root towards the tip of the blade. The diameter of the fan is preferably substantially the same as that of the rotor. The blades preferably taper from root to tip, and the fan may be located in a converging-diverging nozzle. In the form shown, the fan with vanes 6 is mounted on the shaft 2 of an alternator which has a closed-circuit cooling system, and is located in a converging- diverging nozzle formed by the part 12. This nozzle, together with the shaped ring 15, forms a stream-line passage for directing the cooling fluid, which is drawn from the space 13 which is open to the ducts of the circulating system, away from the shaft 2 into the space 14. The cooling fluid sweeps past the end connections 16 and through the channels 19, then flows up and down the ducts 20 and ultimately reaches the space 21 which is open to the discharge ducts of the circulating system. Some of the fluid from the space 14 passes directly to the air-gap 22 and thence through the ducts 20 to the space 21, whilst cooling fluid is also drawn from the space 13 up the ducts 9, 10 and 11 and past the end connections 7 by the centrifugal action of the rotor, and so passes to the space 21 via the air-gap 22 and ducts 20. A fan may be provided at both ends of the machine.