Electrical fuel pump for small motorcycle engine

Abstract

This invention discloses an electrical fuel pump for a small motorcycle engine including an intake socket for introducing the fuel into the pump, a gerotor pump for compressing the incoming fuel, a discharge socket for discharging the compressed fuel from the pump, a DC motor for driving the gerotor pump, a coupling for transmitting the rotation power of the motor to the gerotor pump, and a casing for receiving the intake socket, the discharge socket, the gerotor pump, the coupling and the DC motor therein. The gerotor pump has a pair of engaged rotors, including a toothed inner rotor and a toothed outer rotor disposed eccentrically relative to each other, with a plurality of outer and inner teeth being, respectively, formed on the outer periphery of the inner rotor and on the inner periphery of the outer rotor so that the outer rotor may be driven by the inner rotor through engagement of the inner and outer teeth. A suction effect and a compression effect may be alternately achieved due to gradual changes in the volume of each cavity formed between engaged inner and outer teeth during the rotation of the pair of rotors so as to suck the fuel from the intake socket and then expel the fuel into the discharge socket. The coupling interconnects the DC motor and the gerotor pump in a manner allowing a slight relative axial movement and a slight axial misalignment between the motor shaft and the inner rotor so as to permit easy assembly. Furthermore, the coupling is made of engineering plastic so that power transmission may be achieved without metal-to-metal contact, thus permitting a quiet fuel pumping operation.