GB385470A - Improvements in and relating to electric motors - Google Patents

Abstract

385,470. Alternating-current motors. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. -(Assignees of Nickle, C. A.; 12, Oakland Avenue, Schenectady, New York, and Morrill, W. J. ; 2317, South Wayne Avenue, Fort Wayne, Indiana, both in U.S.A.) Feb. 24, 1932, No. 5560. Convention date, Feb. 25, 1931. [Class 35.] Induction machines; motors with unwound armatures; cores.-In an unwound-armature motor with the poles of the field magnet shaded, means are provided to maintain the fluxes in the shaded and unshaded portions of the poles substantially equal. In the form shown in Fig. 7, the fluxes in the two portions are equalized by fitting exciting coils 18, 19 on the shaded sections which produce flux in the same direction as that produced by the main coil 20. In the form shown in Fig. 13, the coils 46, 47 supply all the excitation, and the coils 46 on the same portions as the shading coils 12 have the greater number of turns ; the coils may be connected in series or parallel and one pair may be reversed. When they are in parallel, a condenser may be connected in series with those on the unshaded portions. The fluxes may also be equalized by increasing the reluctance of the unshaded, section by making it smaller, by the provision of slots or by increasing its air gap at the armature periphery. The rotor may surround the stator, and when of iron should be saturated, and non-magnetic material may be interposed between the magnetic laminµ. Chrome steel may be used for the rotor core which is preferably annular. The induction disc motor shown in Fig. 9 may be modified by shading both poles, and may have more than one stator element.