GB196048A - Improvements in the construction of direct current dynamo electric machines - Google Patents

Abstract

196,048. Newton, F., and Newton Bros. (Derby), Ltd. Jan. 10, 1922. Field magnets; brush-holders; casings; machines with two armatures; terminals and accessories, arrangement on machine.-In a lightweight continuous-current dynamo the field coils surround the armature and are surrounded by a field structure of stampings, as shown in Fig. 5, having a flat exterior surface nearly tangential to the pole face at its centre so that the coresection decreases towards the centre and distortion of the flux is impeded. The form illustrated is a machine for aircraft wireless having a highvoltage armature 4 for the valve plate and a lowvoltage armature 5 on the same shaft for excitation and for the valve-filament current. The light non-magnetic casing 1, which is enclosed to streamline form by end caps, is continued below the machine to form a chamber, closed by a plate 18, for the condensers 15, 16. Ribs 14 in the casing are bored to support the circular end and intermediate laminae 13, of the shape shown in Fig. 6, between which the flat-surfaced laminae 2 are secured by members 20 which are fastened to the laminae 13 by their outwardlyturned edges. The pile of laminae 2 may be twisted through the arc of an armature tooth and the members 20 may lie on the twisted flat surfaces. This twisting reduces ripples in the machine voltage, and the armature slots may be nearly closed for the same purpose. The field coils are curved, as at 12, Fig. 1, to allow insertion of the armature. One brush-holder of the generator 4 is of metal to give a connection to the frame and the other, which is insulated, is brought out to the packed insulated plug-contact 22 below the machine. The terminals of the other machine are brought out to sockets in an insulating-block 24 adapted to receive the loosely mounted pins 26 of a plug 19. This consists of a metal cap containing an ebonite cup 25. The pins pass loosely through the cup, their heads being sunk in recesses, so that they can easily adapt themselves to the sockets. The movement of the pins is limited by a coned ebonite ring 27. A metal cap 28, screwed to the plug 19, may be used for making a water-tight taped joint on to the cable which also prevents tension on the cable from affecting the pin-contacts.