GB273637A - Improvements in and connected with electrical fan and like motors - Google Patents

Abstract

273,637. British Insulated Cables, Ltd. June 30, 1926, [Convention date]. Cores, yokes; brush-holders.-An electric fan &c. motor has a cast steel field magnet made in two halves adapted to receive a single cylindrical exciting coil and disposed within an iron casing, each half of the magnet having a pole projecting through the adjacent part and beyond the outside surface thereof so that an increased length of magnetic leakage path is obtained between the pole tips and the top and bottom of the. magnet. The part 8 of the field magnet, has a downwardly extending pole-piece 54 and the part 9 has an upwardly extending pole-piece 55. Cavities 8<x>, 9<x> in the field magnet receive the field coil 53. The lower end of the armature shaft carries the commutator 25 upon which bear brushes 28 of rectangular cross-section, sliding in metal brushboxes 29; the brush-boxes are held in insulators 31 attached to spokes 35 on a wheel shaped member 36, the rim of which is screwed on to the junction of the upper and lower casing parts 7, 49. The top of the casing 7 is formed with a boss 4 which screws on to a hollow vertical shaft 1. The boss 4 has an annular projection 15 which encloses the ball bearing 16, and to the upper end of the armature shaft is secured an oil or grease cup 18. The lower bearing housing 38 is secured to the spokes 35 and surrounds the bearing 39, the upper end of which is flanged and acts as the seat of the step bearing 40 on the armature shaft. A sleeve 42 on the shaft carries an oil or grease cup 41 and is formed with a helical groove 58 through which lubricant is fed to angular grooves 59 in the bearing surfaces. Holes 60 in the housing 38 allow the lubricant to drain back into the cup 41. A disc 26 below the commutator prevents carbon dust from the brushes entering the lower bearing. The sleeve 42 is slidable upon the armature shaft and engages, by a movable jaw 43, the boss 44 of the fan. The boss of the fan engages the shaft by means of a U-shaped link 45 secured by a cupshaped washer 46 and a nut 47. A thick felt washer 51 serves to prevent the entry of dust into the casing.