Patent GB-190314067-A (GB)
Title: Improved Automatically Reversible Dynamo, to give a Constant Voltage Irrespective of Speed.
Inventor: INRIG ALEC GAVAN
Filed: 1903-06-24
Granted: 1904-05-05
Abstract: 14,067. Inrig, A. G. June 24. Dynamos; commutators; dynamos, regulating.- In an electric generator designed to give a constant voltage irrespective of speed and direction of rotation, and, according to the Provisional Specification, for use in train-lighting systems, the armature a, Fig. 1, (Provisional Specification drawings) is clamped to the fixed casing q by clamps b to which the commutator disc c is bolted, while the field magnets m rotate with the shaft l within the armature. The field-magnet current is varied according to the speed of the sbaft l by an arrangement of governor weights w which slide on radial rods u in opposition to springs v, so as to include a less or greater number of resistance coils r in the field circuit. The disc c, in addition to the commutator segments d, carries a slip-ring e, the disc, segments, aud ring being all insulated from each other. The field magnets having four poles, four brushes f are provided, of which the positive pair bear on the segments d and ring e, while the others bear on the segments d and disc e. The brushes are held up by springs h on levers i, and are carried by levers on a sleeve which is driven by a clutch k. The sleeve is cut away at the part in which the clutch k engages, so that the setting of the brushes is altered when the direction of rotation of the shaft is reversed. The ring e and disc c are respectively connected to the positive and negative terminals. The spider s which carries the resistance coils r has bolted to it a ring t which secures the outer edge of a governor plate x, Sheet 1 (Complete Specification drawings), the inner edge being secured to the hub of the spider by set-screws. The resistances r are connected to insulated contact-plates 2 on the plate x, and are put in circuit by insulated fingers 12 on the governor weights w. The plates 3 with which the fingers 12 also contact are connected to the positive brushes, and the inner contacts 2<a> through the field-magnet coils to the negative brushes. To prevent the accumulators used in the lighting- system from discharging back through the dynamo when the speed of rotation is small, a switch consisting of two fixed contacts 4 and a moving contact 6 is arranged between the negative terminal and the disc c. The contact 6 is carried hy a governor weight 5 which, during slow speeds, is held by pins 8 arranged in levers 9 to break the dynamo circuit. When the proper speed is reached, rollers 13 carried by another governor weight w<1> move the levers 9 to raise the pins 8 ; the weight 5 then flies out, and connects the contacts 4. Should the speed again fall to an insufficient amount, the spring 14 forces the weight 5 back to break the circuit. In small generators for lighting motor cars, carriages, cabs, &c., an ordinary ball governor on the shaft draws the field magnets along the shaft away from the armature to reduce the voltage when the speed rises excessively; a spring compressed during this movement returns the field magnets when the speed falls off.