Patent GB-190425524-A (GB)
Title: Improvements in Electric Lighting of Railway Carriages and the like.
Inventor: IMRAY OLIVER
Filed: 1904-11-23
Granted: 1905-09-28
Abstract: 25,524. Imray, O., [Denham, J.]. Nov. 23. Brush - holders; dynamos, driving; dynamos, regulating.-Relates to an electric lighting system for railway carriages and the like, in which a shunt dynamo is driven by the train or by a windmill &c. to charge accumulators through potential-regulating devices and resistances which maintain constant the voltage generated, a magnetic cut-out serving to disconnect the generator from the batteries when the latter are fully charged. The invention is described as applied when each carriage acts as a separate unit. A multipolar shunt dynamo A, Fig. 1, fixed adjustably to the bogie of the train, is driven by a flanged pulley. The polarity is maintained independent of the direction of rotation by the automatic frictional movement of the brush-rocker (which may be provided with ball bearings), over the commutator as the direction of motion changes, the limiting positions being determined by stops. A resistance 4 in the field circuit is controlled by the core 6 of the electromagnet 5, which is held by the detent magnet 7. An electromagnetic cut-out B controls the main circuit break 9, and also connects the contacts 10,11 which short-circuit the resistance 15 when the dynamo is not excited. The main current also passes through a differentially-wound electromagnetic switch C with one main winding 12 in the charging-circuit assisted by a shunt winding, and an opposing main winding 13 in the discharge circuit, which also includes the variable resistance 14 controlled by the switch C. From the magnet winding 12 the circuit is continued through the motor meter D, (which has a series coil in the battery circuit and starting-coil 18 and armature 17 in shunt), to the storage battery E, and so back to the generator. The meter D gears with a pivoted segment 19, adapted to operate a two-way switch 20, which controls the excitation of the magnets 5, 7. When lamps are switched on, the core of the differentially-wound solenoid C is attracted by the coil 13, and, when the dynamo generates, the main switch 9 is closed and the auxiliary contacts 10, 11 opened, throwing the resistance 15 into the lamp circuit and closing the charging-circuit. The coils 12 now pull the core downwards, the resistance 14 is brought into the lamp circuit, and, as the cells become charged more fully, the pull of the shunt coil 12 increases and more resistance is inserted. In this way the voltage of the lamp circuit is kept constant; if necessary, an additional solenoid in the main dynamo circuit may cut in resistances proportional to the charging- current. The segment-arm 19 geared to the meter D indicates the condition of the cells, moving to its extreme position when the cells are fully charged and re-engaging the gearing when the cells begin to discharge. The resistance 22 included in the meter armature circuit compensates for loss in conversion in the cells, and is cut out by the movement of the coil 23 when the meter moves in the discharge direction. The dynamo is cut out when the cells are fully charged, and again cut in, on discharge, by means of the arm 27, Fig. 2, on the segment 19 engaging the projecting fingers 28, 29 of the weighted levers 30, 33 of the switch 20, Fig. 1. When the dynamo is fully loaded, an electromagnet in the discharge circuit presses a jockey-pulley upon the driving-belt to prevent slipping, or pulls the machine in its slide for the same purpose. To economize space, the shuntwound limb of the cut-out B may be dispensed with, and the field magnetism of the generator used to attract a hinged core B<1>, Fig. 5, carrying a series exciting-coil and normally spring-held so as to connect the contacts 10, 11. When the core is inductively energized, it is attracted to close the main contacts 9, subsidiary carbon contact being provided to take the spark. The core of the solenoid of the differential-action switch C, Fig. 4, is made to operate a piston C' which moves throughout its range in a cylinder built up of metallic discs C<2> insulated from each other and connected to resistance coils. The system may be applied to a train in which the various carriages have separate storage batteries, one dynamo only being used for the whole train. An electromagnetic cut-out in the same carriage as the dynamo serves to control the supply of current to the train leads across which the lamps, batteries, and differential-action switches are connected.