GB190515860A - Improvements in Dynamo Electric Machines. - Google Patents

Abstract

15,860. British Thomson-Houston Co., [General Electric Co.]. Aug. 2. Armatures; field magnets; cooling and ventilating. -To improve the ventilation of field-magnet and armature cores, the laminµ of the external member are divided into groups by means of spacing-blocks or strips of special shape, and the bulk of the air drawn within the rotating core by means of fans is caused to pass out radially through the ventilating- spaces by making the end clamping-plates of the core laminµ with different internal diameters. Figs. 1 and 2 show a vertical-shaft direct-current generator with its internal revolving armature directly driven by a high-speed prime-mover, such as a steam turbine. The outer ends of the spider arms 3 are undercut to engage dovetail recesses 5 in the core laminµ, and are formed with projections 6 engaging shoulders 6<1> on the clamping- plates 7. The laminµ are divided to form ventilating-passages 12 by means of spacing-strips 10 and washers 13 on the bolts 8. Each lamina is provided with three full dovetail recesses 5 and two half recesses, and, to prevent eddy currents in the bolts 8 located between each pair of recesses, the latter are extended to form air gaps 14 between the bolts. The holes for the bolts may be reamered out after the core is assembled. Cylindrical flange portions 15 of the clamping-plates 7 support the projecting ends of the armature conductors. Laminated pole-pieces 33 are secured to the solid field poles 31 by means of dovetail projections 33<1>, and are slotted to receive compensating- windings 36. The laminµ are spaced apart by deflecting-strips 35, the inner ends of which are bent so as to be parallel to tho direction of the air currents set up by the armature. The outer ends of the spacing-strips may be reversely inclined to the inner ends, as shown. An annular member 41, secured to the field ring 40, supports a cylindrical drum 42, enclosing the armature and forming a casing for the blades 43. The upper clamping- plate 7 is made with a larger internal diameter than the lower clamping-plate, so that the bulk of the air drawn into the core through the upper opening is expelled radially through the passages 12. In a modification with an external armature, the laminµ are spaced apart by deflecting-strips such as 35.