GB125673A - Improvements in or relating to Dynamo Electric Machines. - Google Patents

Abstract

125,673. Vickers, Ltd., and Barclay, S. F. July 23, 1917. Armatures and field magnets, cooling; cores.-Relates to the cooling of dynamo-electric machines, particularly high - speed alternators, and consists in employing two separate air currents, one passing axially through the rotor, the other passing radially, and preferably in axial direction also, through the stator. The radial and axial ducts in the stator communicate through openings of varying size so as to give the required air distribution. Fig. 1 is a partial section through the axis of machine, and Fig. 2 is a part transverse section. The air for cooling the rotor enters at one end of the machine through an inlet 17, and is drawn through the chamber 30 beneath the rotor end connexions 7, along the axial ducts 24 beneath the rotor conductors 6, below the opposite end connexions 7 and through the fan 25 to the outlet 27. Additional ducts 34, Fig. 2, may be formed in the rotor core to carry air and also to regulate the magnetic density. The stator is built up of annular laminations 3 which are separated in the axial direction by radial strips 12, thus forming radial passages for the air current. Axial ducts 14 are also formed through the stator, and the continuity of these ducts is maintained by incomplete rings 15. The gaps 16 in these rings are on the side remote from the machine axis, and afford communication between the axial ducts 14 and the radial ducts 11. The rings 15 may be secured to radial strips similar to the strips 12. The gaps 16 are preferably larger near the centre of the stator. The air current for the stator is drawn in at each end through inlets 17, 18 by fan blades 19, 20 and passes along the air gap and outwards through the radial passages 11. The air also passes over the end connexions 10, and through the axial ducts 14 towards the centre of the machine, gradually escaping through the gaps 16 into the radial passages, and finally emerging through openings 22 in the casing. Covers may be placed over the ends of the axial ducts 14 to regulate the air flow. The fan 20 may be arranged to give a stronger current than the fan 19 in order to compensate for the inequality in the cooling of the rotor due to the air entering it at one end and leaving it at the other. This may alternatively be compensated by differently shaping the passages 29, 32. External fans may be used instead of mounting the fans on the rotor core.