GB172703A - Improvements relating to the ventilation of dynamo-electric machines - Google Patents

Abstract

172,703. Field, A. B., and Metropolitan- Vichers Electrical Co., Ltd. Sept. 7, 1920. Armatures and field magnets, cooling and ventilating.-For ventilating a dynamo, a fan 17 is used on the rotor together with a stationary end bell 20 provided with partitions so arranged as to form a chamber to which air is sucked from atmosphere by the fan, and a second chamber 29 into which the air is delivered by the fan and from which it passes to ventilate passages 14, 15 in the stator, to the air gap 12, and through a bypass 32 into a third chamber 30 from which it passes to passages 8 in the rotor through an annular outlet 17 of smaller radius than that of the fan. The end bell 20, which is shown in inside elevation in Fig. 2, has double walls 21, 22 merging together at the outer edge and enclosing the inlet chamber 25. The inner wall has a coned part 23 brought close to a ring 18 inside the fan 17 so as to define the annular suction inlet 27 of the fan. Part of the air is delivered from the chamber 29 to the air-gap and statorducts 14, 15 and part passes through a radial by-pass 32 in the end bell, defined by a passagethrough the chamber 25, to a chamber 30 around' the shaft. This chamber at one end is closed by a cover 31 and at the other it directs the air into axial ducts 10 in the rotor and thence, byradial ducts 11, into the air gap. The supply to the rotor ducts 10 is at substantially the same pressure as that of the air-gap so that the pressure added by the centrifugal action of the rotor ensures free ventilation of the rotor.