Patent ID: 6102684
Filing Date: 2000-08-15
Classification: F02M,F04C

Abstract:
A positive displacement gear rotor type fuel pump comprising:an electric motor which drives the fuel pump;an inner gear rotor driven to rotate on an axis by the motor and having radially outwardly extending teeth;an outer gear rotor having radially inwardly extending teeth and driven to rotate by the inner gear rotor on an axis spaced from and parallel to the axis of rotation of the inner gear rotor, the outer gear rotor having at least one more tooth than the inner gear rotor;a plurality of fuel pumping chambers defined between the teeth of the inner gear rotor and outer gear rotor, the volume of each fuel pumping chamber enlarges to draw fuel into the fuel pumping chamber and ensmalls to increase the pressure of the fuel in the fuel pumping chamber and to discharge the pressurized fuel;an outlet port plate disposed adjacent the inner and outer gear rotors and having a plurality of spaced apart outlet ports through which fuel under pressure is discharged from the chambers of the inner and outer gear rotors, the outlet ports are radially elongate, circumferentially spaced apart and have their radially innermost portion disposed on or slightly radially outwardly of an arc formed by connecting the initial points of contact between the inner gear rotor teeth and the outer gear rotor teeth, the outlet ports are constructed, spaced apart and arranged so that the fuel pumping chambers do not directly communicate with each other through the outlet ports; anda valve adjacent the outlet ports and constructed to prevent the reverse flow of fuel from downstream of the valve back through the outlet ports whereby the valve prevents pressurized fuel discharged from the fuel pumping chambers from reentering other fuel pumping chambers which are at a lower pressure and the construction and arrangement of the outlet ports prevents the fuel in a fuel pumping chamber which is at a higher pressure than fuel in other fuel pumping chambers from entering the other fuel pumping chambers to reduce the noise associated with the rapid compression and transformation of fuel vapor to liquid fuel and thereby reduce the noise of the operating fuel pump.