GB222273A - Improvements in dynamo electric machines - Google Patents

Abstract

222,273. Tilling-Stevens Motors, Ltd., and Whitehorn, H. K. Aug. 11, 1923. Pole-pieces, cores, and yokes; commutating poles; casings; exciting. - In a machine which runs in one direction only and in which the magnet poles are each divided or substantially divided into two portions a, b united in pairs by yokes c and so arranged that each adjacent pair of portions a, b of like polarity forms one main pole, a series coil h is wound on that portion only of each main pole which is weakened by armature reaction. The pole sections are unequal, that of the portions b being the smaller, and the yokes are stepped, as shown, or tapered to give the required reduction of section. The main coils g of the machine, whether shunt or series, span both portions of each pole. The smaller portions may have removable tips to allow insertion of the coils or the coils may be sufficiently large to enable them to be slipped over the poles. Commuta.ting poles k of similar polarity to the smaller portions b may be mounted at the mid-points of the yokes adjoining the steps. The magnets, which may be laminated, are secured in a light non-magnetic casing d<1> of aluminium or the like having strengthening ribs d<2>. In an alternative form, there are no coils g spanning the whole poles, the alternate portions, such as a, being unwound, and in another form, the two portions a, b have equal cross-sections.