| 摘要 |
An in-tank type electric motor fuel pump with a fuel inlet end cap, a fuel outlet cap, a case coaxially joining the end caps to form a pump housing, an electric motor mounted in the housing having a stator with spring-retained permanent field magnets surrounding the motor armature, and a gerotor pump in the housing rotatably driven by the motor armature. An inlet port plate, an outlet port plate and a cam ring sandwiched between the plates form a gerotor pocket axially between the plates, and inner and outer gear rotors are disposed in the pocket with intermeshing teeth defining circumferentially disposed expanding and ensmalling pumping chambers. A pair of alignment and fastening screw pins are the sole hardware for clamping the plates and cam ring in tightly sandwiched relationship and holding the pump unit together in properly axially, radially and angularly oriented component relationship in precision final assembly as an operable gerotor pump. The screw pins each have a cylindrical smooth surface shank portion precision fitting in smooth wall precision aligned bores in the plates and cam ring. The screw pin threaded end threadably engages a threaded portion of the inlet plate bore hole that is slightly reduced in diameter relative to the smooth surface bore holes. The radial tolerances between the pin and inlet plate hole threads are larger than that between the pin shank smooth portion and the associated smooth surface alignment bores in the plates and cam ring to prevent alignment distortion from thread seating stresses. The screw pins also have axially elongated and slotted screw heads that serve as fail-safe stops limiting loosening motion of the magnets. The pump rotors have predetermined fixed assembly axial and radial clearance dimensions relative to the pump plates and cam ring respectively established and maintained in assembly by the screw pins fitment in the plates and cam ring.
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