A commutation performance and wear of carbon-fiber brush in gasoline

It is well known that many small DC motors are used in automotive electrical equipment. Among them, a DC motor for a fuel pump has a distinctive feature in that its brush and commutator work in gasoline. In the authors' previous reports, it has been made clear that the wear of metal-graphite and carbon brushes is much larger in gasoline than in air, and severe wear was sometimes observed. In this paper, a carbon-fiber brush is tested for wear and sliding performance in gasoline and compared with a carbon brush. Consequently, it was found that the carbon-fiber brush is better than the carbon brush in terms of commutation ability and wear in gasoline. When severe wear was observed, a carbon film fully covered the commutator surface under both carbon-fiber and carbon brushes.