A study of commutation arc of DC motor for automotive fuel pump

Many small DC motors are used for automotive electrical equipment. In particular, motors for fuel pumps play the important role of supplying the engine with gasoline. In these motors commutation is done in gasoline. A new test apparatus has been developed for the investigation of commutation phenomena in gasoline. The duration of the commutation arc in gasoline was found to be shorter by about 30 approximately 50% than in air, in cases of both Cu and Ag/Ni. The value of the residual current of commutation in gasoline is generally smaller than in air. The arc duration is proportional to the residual current, and the slope in gasoline is smaller than in air. It is caused by the difference of the arc voltage. The carbon adhesion on the commutator surface in gasoline is much less than in air.<>