GB320563A - Improvements in or relating to dynamo-electric machines - Google Patents

Abstract

320,563. Baum, F. G. Dec. 1, 1928. Armatures and field magnets, cooling; enveloping in special media.-A dynamo-electric machine is cooled by directing on to the interior surface of its stator at a number of points along its length simultaneously currents of gas and a spray of oil or other suitable liquid which is collected and recirculated. When a non-combustible gas, such as nitrogen or carbon dioxide, is employed the risk of fire in the machine is reduced. Fig. 1 shows an enclosed machine in which oil is forced by an external pump 17 from a reservoir 16 through the outlets 19 of the hollow shaft 1. These outlets are connected to spraying devices 21, between the poles 4. The jet openings preferably register with the ventilating ducts 8 in the stator iron so that the emerging oil passes as a film over the iron to'the outer periphery of the stator from which it runs down to a compartment 14 at the bottom of the machine and from there to the reservoir 16 for recirculation. Provision is also made for the passage of gas currents from the rotor rim either through the poles or in the interpolar spaces. Fan blades on the rotor assist the internal gas circulation. In place of being introduced through a hollow shaft, the oil may be led, as shown in Fig. 3, from the pump through conduits 23 to an annular trough 24 inside the rotor rim with spraying outlets 27. It, as shown in Fig. 5, may be conveyed by tubular scoops 28 which lift the oil from the bottom of the machine casing into the rotor trough. These constructions are particularly suitable for squirrelcage machines. Specifications 170,946 and 301,838 are referred to.