Patent GB-193940-A (GB)
Title: Improvements in and relating to windings for the armatures of dynamo electric machines
IPC: H02K3/00
Filed: 1921-11-28
Abstract: 193,940. Sayers, W. B. Nov. 28, 1921. Rotary machines; coils and conductors; commutators; windings.-An interchangeable tubular unit for dynamoelectric machines comprises a winding consisting of oppositely-twisted helical elements a, Fig. 1, some of which have electrical and magnetic conductivity and some electrical conductivity only. The elements, which are joined in pairs at one end by clips f, Fig. 9, and at the other end extend to form commutator segments g, are rotated between a fixed magnet system and a stationary inner iron member j<3>, Fig. 4. mounted on ball-bearings k on the driving shaft h. The segments are supported by a disc h<1> on the shaft and are centred with regard to the shaft axis by means of an expansible ring h<3> and screws h<5> after the cylindrical unit has been placed in position. Dogs k<12> on the dise h<1> engage certain of the segments and convey the driving torque. The clips f are supported by an insulated flange h<6> on a member h<2>, feathered on the shaft, and they are secured by a segmental grip-ring h<8> screwed to the member h<2>. Screws h<13> in the end member h<2> bear on a plate i and enable the member h<2> to be drawn along the shaft to stretch the complete cylindrical unit to the requisite rigidity. Fig. 1 shows a two-pole construction with the helical elements in two layers, but for a four-pole machine four layers are used with an inner iron member having two-part iron poles j<1>, Fig. 16, lozenge-shaped to conform to the effective zone of the helical conductors, the magnet poles k<1> being similarly shaped, as shown in the developed diagram, Fig. 16. Triangular commutating poles k<2> and portions j<2> corresponding on the inner member may be used. The inner member may be of solid iron or of strip or wire made of tungsten steel or other material having retentivity and being embedded in an insulating composition. A form of alternator is described in which a stationary cylindrical unit of helical conductors is supported within the bore of a laminated iron stator and encloses a rotary electromagnet. The compound helical elements a mav be secured in groups, as shown in Figs. 20 and 21, by insulated rivets P. The sections l are divided into two parts with insulating pieces l<7> between them and between the components of neighbouring sections to give ventilation. In this form, every third electrically-conducting element c is brought out to form a commutator connection, and the intermediate conductors are connected electrically in series. The ends of thesections are supported in insulated housings l<2> formed in the driving end-members l<3>, and they are secured by wedges l<5> drawn in by screws l<6> and retaining-pins l<9>. The compound elements. consist of annealed thin sheet iron strips b', Fig. 10, separated by varnished paper, and copper strips c with intervening insulation d applied spirally to leave ventilating spaces. The iron mav be wider than the copper so as to project slightly beyond it at the edges and allow bending over. In the form shown in Fig. 25, the iron h is channelled to surround the copper c on three sides, the fourth side being enclosed by projecting strips of insulation. The iron may be wrapped around the copper and be pierced or cut at intervals to reduce, its section locally. The iron strip may be waved or corrugated transversely, to give resilience and ventilation, or it may be in the form of a spiral. Alternatively, iron may be electrolytically coated with copper over part or all of its surface, or the compound bar may be made by drawing off from a mandrel a helically arranged tubular group of iron and copper wires which is then flattened between rolls. According to one Provisional Specification, in such fattened strips the copper may predominate over the iron strips or the flattening may be so regulated as to cause the copper to interlock with the iron and give the maximum mechanical continuity with the minimum waste of space. Also that iron and copper strips in contact may be employed, these being pressed together during use. According to the other Provisional Specification, helically disposed insulated strips of magnetic material may be placed between adjoining compound bars or coils, and iron gauze, cut diagonally, may also be used. Form-wound coils may be employed, with oppositely-disposed helical end portions bent to lie on a cylindrical surface and optionally joined by a straight central part of the coil parallel to the axis of rotation of the machine. To enable the compound conductors a, Fig. 29, to interlock when associated to form a cylindrical structure, they are curved in transverse section, as shown, and helically bent or twisted so that when a number of conductors is arranged in juxtaposition thev constitute a tubular construction substantially free from undesirable air spaces between the conductors.