GB190305561A - Improvements in or relating to Dynamo Electric Machines. - Google Patents

Abstract

5561. Porsche, F. March 10. Dynamos, regulating.-In a driving-system for a motor car or other vehicle in which a dynamo driven by an explosion engine &c. supplies current to electric motors which drive the wheels, the voltage of the dynamo is regulated automatically to keep the watts constant, so that the explosion engine constantly works at the most efficient power and speed however the load on, the speed of, and the current taken by the motors vary. Figs. 1 and 2 show an arrangement in which the required regulation is effected by the cutting in or out of field - magnet coils. The field magnets 3 are mounted loosely on a fixed sleeve 4 within the armature 2, and are constrained by a spring 8 attached to them and to the fixed bracket 24. When the motors slow down through an increase in the :road resistance, the increased current taken by them from the armature 2 increases the attraction between the armature 2 and field magnets 3, thereby drawing the field magnets round against the action of the spring 8. The field - magnet winding 9 consists of a flat spiral of copper band having its coils insulated from each other but bare at their edges. The brush 10 supplying the exciting-current is rigidly held over an insulating- plate in an inclined recess 11 in the winding 9 with one corner in contact with the edge of the outer coil. When the field magnets are moved round as described above, the brush 10 contacts with coils lying within the outer coil, so that the magnetic field is reduced, the final result being that the voltage falls to maintain the watts constant. A shaft 5 carrying arms 6, 7 which project through slots in the sleeve 4 into the field magnets is connected to a dash-pot 15 to steady the motion of the magnets. The above arrangement may be applied to the case in which resistances are switched in or out in parallel to the winding 9 for the same purpose. In another case, a stud on the magnets engages in a helical groove in the sleeve 4, so that the magnets move along the sleeve and increase the gap between their inclined faces and those of the armature when they are drawn round by the armature. The commutator brushes 17 are supported from brackets 19 on the field magnets in the first case, and thereby maintain their proper position relative to the field. In the second case, they are carried from a ring which is rotatable on a fixed bearing and through holes in which pass pins projecting from the magnets parallel to the dynamo shaft ; in this case also the brushes move round with the field.