GB418443A - Improvements in or relating to electro-magnetic brakes - Google Patents

Abstract

418,443. Eddy-current brakes. LEITNER, H., 408, Abbey House, Victoria Street, London. April 20, 1933, Nos. 11610/33, 19787/33, and 9702 /34. [Class 103 (i).] An eddy-current brake for vehicles and other purposes comprises a magnetizable carcase like that of a homopolar dynamo of the cylinder type but having inner and outer polepieces of such form as to produce a circumferentially gapped intense magnetic field in which a hollow cylindrical armature is arranged, sufficient internal space being provided in the carcase for a coil or coils whilst leaving a smaller air gap between the poles for the armature. In one construction, Fig. 6, a main field member 18 of U-shaped cross-section has fitted to it cylindrical members 25, 26 having a number of circumferentially spaced pole extensions 21, 22 between which rotates a metal cylindrical armature 16 secured to the shaft 17 to be braked. Eddy currents are set up in the armature when the winding 20 is energized. In Fig. 11, field members 31, 32 integral with the polepieces are bolted to the cylindrical flange 30 of a disc, or similar field members may be bolted to the flat side of a disc. An arrangement is also shown in which the field member has two-pairs of concentric polepieces with a winding for each pair and the armature has a pair of concentric cylindrical parts extending into the annular gap between each pair of polepieces. Fig. 1 shows a pair of armatures 16 secured to the same shaft 17 or to separate shafts and rotatable between polepieces 11, 12 extending oppositely from cylindrical field members of which the outer one 4 is divided longitudinally and the two-parts bolted together and is spaced from the inner one by a rib 8. A similar arrangement may be obtained by bolting together, back to back the field members of two constructions such as shown in Fig. 6. In Fig. 13 is shown a pair of field systems with the polepieces 21, 22 extending towards each other and a single armature 39, 40. The armature may be of aluminium, duralumin, copper, magnesium, &c. The field system may be rotated and the armature be stationary or rotated in the opposite direction or the field system may be dragged around by the reaction on it, to a limited extent to apply a mechanical or other brake as described in Specification 418,496. Regulation of the braking action may be effected by varying the voltage applied to the coils or by a rheostat or by varying the number of coils energized or their connection in series, parallel or series-parallel or by sliding an iron sleeve over the poles.