Homopolar machine with improved brush lifetime
View Patent ↗A homopolar machine which exhibits reduced wear and prolonged brush life. Current collectors or brushes are mounted so as to maintain substantially constant contact pressure and so that all of them are polarized negative. Brush holders are provided which facilitate the application of precise and constant contact pressure in a region of very high magnetic forces.
1. A homopolar machine comprising:
a shaft;
an armature assembly coupled to the shaft that includes a cylinder having a pair of spaced apart generally radially extending flanges;
first and second stators arrays that encircle the armature assembly;
a negative bus connected to a first stator;
a positive bus connected to a second stator;
a first negative brush assembly carried by said first stator for contact with said armature at one location; said brush assembly including brushes, an actuator and a holder designed to effect said contact with said armature;
which holder includes (a) radially aligned stem deposed between a pair of parallel flat plates that are mounted in fixed relation to said first stator and (b) a slidable component which carriers a plurality of said first negative brushes and which is slidable between said parallel plates;
said stem being formed with a pair of opposed parallel surfaces that are perpendicular to said flat plates, and said slidable component including a pair of flexible heads that engage said opposed stem surfaces; and
a second negative brush assembly carried by said armature for contact with said second stator, as a result of their negative charge, the lifetime of said brushes is substantially extended compared to comparable positively charged brushes.
2. The homopolar machine in accordance with claim 1 wherein said flexible heads include a stack of generally parallel ribbons cut by EDM from conductive metal.
3. The homopolar machine in accordance with claim 2 wherein said heads are mounted so that said ribbons are flexed against said opposed surfaces.