Improvements in the cooling systems of electric machines

548.210. Cooling dynamo-electric machines. BRUSH ELECTRICAL ENGINEERING CO., Ltd., and PRICE, H. T. March 28, 1941, No. 4174. [Class 35] Relates to cooling means for totally-enclosed machines, particularly induction motors, comprising separate closed internal air cooling and external cooling by air from the atmosphere. The stator core 11 is formed at its outer periphery with longitudinal recesses 22a, 22b ; thin plates are fitted into grooves in the sides of some of these recesses (into alternate sets of three recesses 22a in Fig. 2 so as to close these to constitute the internal system) the alternate sets of three open recesses forming part of the external cooling system. In order to divide off the two systems an annulus with ports 26b that expose the ends of the unclosed recesses in the outer space 14 and ports 26a which expose the ends of the others to the interior space 19 is fitted at both ends between the end shields 17, 18 and the stator. The external fan 15 blows air from outside through the peripheral space 13, through the open stator recesses and over the closure plates of the closed recesses. The internal fan 26 circulates the interior air through the closed recesses. A heat exchange is thus provided between the exterior and interior systems. All the recesses may be closed in which case interior air passes through some of them, exterior air through the others and exterior air over all the closure plates.