Brush assembly for dynamoelectric machines

#1. Field of the Invention

#This invention relates to a brush assembly used in dynamoelectric machines for the transfer of current from a stationary brush magazine to a rotating contact part with stationary brush boxes, which mechanically and electrically are connected with the supporting structure, to receive and radically guide the brushes whereby the brushes are removable for control and replacement purposes while the machine is running and under voltage.

#2. Description of the Prior Art

#A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

#FIG. 1 is a perspective view of a brush assembly for dynamoelectric machines in a highly simplified form;

#FIG. 2 is a top view of a brush carrier element;

#Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 thereof, which is a simplified representation of the slip ring portion of a dynamoelectric machine, the rotating contact part (slip ring or commutator) is designated by 1. The sides 2 of the supporting structure are anchored in an electrically insulated way on a foundation plate 3. Brush magazines 4 are rigidly fastened between the supporting structure sides 2. The brush magazine 4 is designed as a box girder. The axially running side walls are spaced by means of crosspieces 5 so that brush boxes 6 are formed. Each crosspiece 5 has a slot 7, the depth of which corresponds approximately to half of the height of the crosspiece. The edges of the brush boxes pointing towards the outside are rounded off to facilitate the introduction of the brushes, as for example shown in FIG. 4 and labeled 4' and 5'.

#FIG. 2 shows a plug-in unit for several brushes. The plug-in unit comprises a plate 8 with several finger-shaped projections 8' corresponding to the number of brushes. The projections 8' reach into the brush boxes 6 and rest against the radially extending wall of the brush boxes 6 when viewed from the end of the rotating contact part 1 (slip ring or commutator). Constant force springs 9 are fastened on plate 8 by means of rivets 11 and by placing in between spring carrier elements 10. The spring carrier elements 10 are provided with recesses 12 on both sides at the lower section, i.e. on the contact part side, and the ends of the spring carrier elements 10 are widened by additionally riveting on a small stop plate 13. As can be noticed from the sectional representation of FIG. 4 and from the view according to FIG. 6, each brush 14 has a top fitting 15 of copper sheet which is fastened to the brush 14 in an electrically conductive manner. The top fitting 15 has projections 16 on the side towards the spring carrier element 10 whose ends are bent towards each other. These projections laterally embrace the spring carrier element 10. The width of the projections 16 is larger than the length of the recessions 12. By introducing it in an inclined fashion, the brush can be made to slide on the spring carrier element 10 (and pulled off again). The electrical connection between brush 14 and brush carrier plate 8 is effected by means of stranded brush wire (brush flexibles) 17 which is fastened, on the one hand, on the heat fitting 15 and, on the other hand, on the brush carrier plate 8. The upper end of the brush carrier plate 8 is designed as an insulating handle 18 (FIG. 2). Additionally, the insulation handle 18 is shielded from the remaining brush carrier element by means of an insulating plate 19 which serves, at the same time, as a protection against a contact to the brush flexibles and the brush bars. In this fashion, the safe introduction or removal of the plug-in unit is possible during operation and under voltage.

#The electrical connection between the brush carrier element 8 and the brush bar 4 is effected, as shown in FIG. 4, by means of a plug-contact arrangement. One contact part comprises spring contact laminae 20 which is fastened on the brush carrier element 8 by inserting therebetween a conductive spacer 21. The brush bar 4 itself forms the other contact part.