Carbon Brush and Flat Commutator Wear of DC Motor Driving Automotive Fuel Pump in Various Fuels

The authors have been reporting the wear of brush and carbon flat commutator mainly in gasoline and at the high commutation inductance of 300 μH so far. As a result it can be made clear that brush wear is evaluated by total arc energy. In this paper commutation period, arc duration, brush wear and other characteristics are examined in gasoline, ethanol and ethanol 50-gasoline 50% at the commutation inductance of 80 μH Consequently arc durations are found to be largely dependent on fuels, the shortest in gasoline, next in ethanol 50% and the longest in ethanol. However, brush wear is the lowest in gasoline, next in ethanol 50% and the highest in ethanol. Further, in the present tests brush wears are very small compared with the previous results due to short arc duration. Therefore, mechanical sliding wear should be considered as well as erosion by arc, and a wear model of the commutator is proposed.