GB518207A - Improvements in or relating to dynamo-electric machines - Google Patents

Abstract

518,207. Cooling dynamo-electric machines, PATENTVERWERTUNG GES.HERMES. Sept. 24, 1938, Nos. 27932 [Convention date, Sept. 25, 1937], 27933, 27934, 27935. [Convention dates, Sept. 30, 1937], 27936 [Convention date, Oct. 1, 1937], 27937 [Convention date, -Oct. 2, 1937], 27938 [Convention date, Oct. 4, 1937], 27939 [Convention date, Oct. 5, 1937], 27940 [Convention date, Oct. 29, 1937] and 27941 [Convention date, April 5, 1938]. [Class 35] In an enclosed dynamo-electric machine having a circulating inner cooling medium cooled by an outer cooling medium, the stator magnetic parts 7 are supported by longitudinal cooling pipes 9 through which the outer cooling medium flows, the pipes extending between and being supported by end plates 1, and an outer cover 2 which carries substantially no load extends between the end plates and provides an enclosed space for the inner cooling medium To reduce friction when liquid such as oil is employed as the inner cooling medium, the rotor is made long and narrow and may be encased, or it may be solid. Passages for the cooling liquid are provided in the stator and rotor. The stator laminations have recesses which may be of dovetail form interlocking with supporting strips 8 welded to cooling pipes. Strengthening rings 80 may be provided. The pipes may be bent outwardly as shown at one or both ends of the stator to facilitate assembly of the laminations. The internal liquid is circulated by centrifugal pump 14 or a helical pump 140 and'external air is forced through the pipes by a fan 13. Feet 15 and suspension eyes 16 are secured to or formed integral with the end plates. A dome 17 mounted on the cover serves for introducing cooling liquid and acts as an expansion vessel, and the connections to the motor may be led in through this dome. To avoid 'packing, all screw holes situated below the liquid level are formed as blind holes. In a modification, the oil expansion vessel is arranged at one end of the machine, preferably at that end which is traversed last by the outer cooling air. The vessel is also used as a terminal box. To allow for expansion and contraction of the oil, the connections which pass the wall of the vessel are given a small clearance so as to form breathing apertures. In a further modification, Fig. 7, wherein a gaseous internal cooling medium is employed, the stator laminations are carried by supporting ribs 2 each welded to a pair of cooling pipes 3. Reinforcing rings 4 and a guide plate 8 are also provided. The pipes are surrounded by an outer cover 6 of thin sheet metal and an intermediate partition 7 which may consist of several sector-like ports is provided inside the system of pipes for guiding the air. A terminal box 21 is connected, e.g., by welding to one end ring 5. The stator cooling channels 23 are preferably of the same pitch as the winding slots but the clamping rings 24 are provided with larger slots of larger pitch and are spaced from the laminations by sheet metal strips 25 arranged edgewise. The cooling pipes are not necessarily of circular cross-section and may be of metal strips welded together and formed with projecting webs or flanges