| 摘要 |
An electric motor fuel pump has an inner gear rotor and an outer gear rotor each with a plurality of radially opposed intermeshing teeth each having a pair of driving surfaces and defining circumferentially disposed expanding and ensmalling pumping chambers through which fuel is drawn and then discharged under pressure. The inner gear rotor is coupled to a motor armature journalled for rotation within a fuel pump housing to drive the inner gear rotor and the associated outer gear rotor. The teeth of each gear rotor have a step formed thereon providing a pair of offset driving surfaces on at least each driving face of each tooth and preferably offset trailing surfaces on each trailing face of each tooth. The stepped tooth profile permits greater eccentricity between inner and outer gear rotors which increases the fuel displacement of the gear rotors. The stepped tooth profile also provides more teeth for a given pitch diameter and increased design freedom which facilitates optimization of the drive angle between mated gear rotors.
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