Patent GB-151580-A (GB)
Title: Improvements in or relating to electric power transmission systems
IPC: H02P9/00
Filed: 1920-05-01
Abstract: 151,580. Fraser, E. M. Sept. 19, 1919, [Convention date]. Machines with two or more armatures; brushholders; commutators; windings.-A power-transmission system comprises a structurally combined dynamo and motor having a stationary field winding with main and auxiliary poles laterally displaced and in alined or staggered relation, a generator winding driven by the engine, and the motor winding connected to the driven shaft through its commutator and a spider. The generator and motor windings are placed between the teeth of laminations. The main poles of the field structure are provided with a series coil and two oppositely-disposed poles are provided with a shunt coil and a coil for fixing the polarity of the field after a period of rest. The auxiliary poles are provided with a coil, the current through which may be varied by means of a shunt resistance, and the direction of energization may be reversed. The generator winding is energized from a battery to start the engines, and switches are provided to vary the connexions to obtain variable speeds, braking, and reversal. The commutators of the machine are of the disk type. The stationary field structure 1 consists of four main magnets 4, Figs. 1 and 3, and four auxiliary magnets 5. The cores 7 of the main magnets 4 are provided with a series coil 8, and two oppositely-disposed cores 7 are provided with a shunt coil 9 and a coil 10 connected directly across the battery to ensure definite polarity of these cores after a period of rest. The cores 11 of the auxiliary magnets are provided with a series coil 12. The coils are held in position by laminated pole-shoes 13. The motor winding 3 consists of a number of copper conductors 22, Figs. 1 and 2, placed between the teeth 23 of iron laminations 23 arranged opposite the main and auxiliary field magnets 4, 5. One end of this winding rests upon a rotatable bracket 24 and the other ends of adjacent conductors are connected by means of clips 26 to form a single winding. The motor winding 3 is connected to the driven shaft 6 by means of its commutator 27, ring 28, and a spider 29 secured to the shaft 6. The commutator 27 is of the disk type, and comprises a perforated annulus 30, copper strips 31, and commutator bars 32. The strips 31 and bars 32 are insulated by mica sheets 33 and are secured to the annulus 30 by means of insulated copper rivets 34; and the commutator is secured to the clips 26 by screws 36. Each commutator brush 37 is mounted upon a lever 38, the support 39 of which is mounted upon an insulated fixed support 40. The brush 37 is connected to a connector ring 41 by a lead 42. The generator winding 2 is connected to the driving-shaft 20' through a spider 43 and consists of a number of copper conductors 48, Fig. 1, placed between the teeth 50 of iron laminations 45, 46 and connected to a commutator 48 similar in construction to the commutator 27. The main and auxiliary field magnets may be alined as shown in Fig. 3, to reduce to length and consequently the resistance of the generator winding to a minimum, or they may be staggered to the extent of half a pole pitch. In Fig. 3 the generator winding is shown in full lines and the motor winding in broken lines.