Patent GB-341164-A (GB)
Title: Improvements in electric motors
IPC: H02K9/06
Filed: 1929-11-05
Abstract: 341,164. Motors. HOSEASON, D. B., Grimsworth, Groby Road, Bowdon, Cheshire, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Bush House, Aldwych, London. Nov. 5, 1929, No. 33661. [Class 35.] Motors, cooling; coils and conductors; polepieces and cores; armatures and field-magnets, cooling.-In a continuous-current motor of the type which is cooled by external air the armature core has at least two radial ventilating spaces connected by a comparatively large number of small axial ducts, provision being made for drawing a large volume of high-velocity air from the commutator end to outlets at the other end of the machine, some of which air passes between the poles while a relatively large part passes through the commutator spider and passes, in part, substantially radially outwards through the armature end windings and commutator connections and in part into the axial core ducts at the commutator end of the armature; additional air is also drawn axially into the motor at the non-commutator end, a part of which flows directly through the axial ducts to the radial spaces while a part flows radially at the non-commutator end of the machine to outlet openings. The air flow, which is divided among the paths in approximately the proportions stated below, may be produced by a single fan at the non-commutator end and the radial spaces in the armature core may be spaced at increasing axial distances as shown in Fig. 4. In addition, the axial ducts on the two sides of the radial spaces may be collinear in some places and staggered in others to give air turbulence in the radial spaces, and the armature and field coils may be arranged in tight contact with the iron to give increased thermal conduction. These arrangements of core ducts and spaces and of thermally conducting contacts are as described in Specifications 337,883, [Class 35, Dynamo-electric generators &c.], and 340,690 and form per se no part of the present invention. In the form shown in Fig. 4, the armature laminae have two sets of axial ducts 28 near to the coil slots and two radial spaces 29 which divide the core into parts of increasing thickness away from the commutator end and coincide with transverse channels 32 in the poles. Air is drawn in at the commutator end B through openings 15 and at the other end C through openings 18 in the end bracket 16 by means of a deep-bladed fan 20 shrouded at 21, 22 and mounted on the coilsupporting ring 23 which is spaced from the clamping ring 4 by ribs with intervening openings 25 for cooling air. The ring 4 also has air openings 26. The arrows denote the air paths as follows :- A total emergent air ; B air entering at commutator and divided into D air passing between poles and E air passing through commutator spider; F and G air passing from the spider through the coil ends and armature respectively ; C air entering at the non-commutator end and divided into I air passing into armature ducts and H air passing over the back coil ends. The ratios of the volumes of air flowing through the different paths in a given time are approximately as follows:-C==30 per cent of the total air flowing through the machine ; I=30 per cent of C; H=70 per cent of C; D=56 per cent of A; E=13À5 per cent of A; and F and G each=50 per cent of E. The armature slots, Fig. 1, are tapered and the taped conductor bundles are similarly shaped, the lower range 35 being deeper than the upper range to equalize the sections. A space 36 below the coils enables them to be wedged tightly against the slot walls by the banding 37 for good thermal contact which may be assisted by a layer of cement between the coil and slot wall. The pole cores may be tapered, the field coils being internally tapered and forced into contact with the pole sides by springs for good thermal contact. Spaces 13, Fig. 4, are left at the front and back surfaces for ventilation. The core spacers 30, Figs. 3 and 4, are thin to offer a minimum obstruction to the air in the spaces 29 and the local tooth spacers may consist of plain blades 31, L-shaped plates 31<a> or bent-up parts 31<b> of the laminµ. Alternatively, the known form of combined body and tooth spacer 31<x> may be used. The spacers may be spot welded to the laminµ.