Electric fuel pump

The electric fuel pump is a device that continuously sucks fuel out of the fuel tank and provides the fuel system with a specified pressure and flow rate of fuel. Based on the function of the electric fuel pump, it can be known that the performance of the electric fuel pump will directly affect the working performance of the engine.

The electric fuel pump is the "heart" of the fuel supply system of an EFI engine. There are two arrangements for electric fuel pumps in the fuel supply system. One is the external type, that is, the fuel pump is connected in series outside the fuel tank. The other is the internal type, that is, the fuel pump is installed in the fuel tank and immersed in gasoline. In this way, the fuel pump is easy to dissipate heat, has low operating noise and long service life, so it is widely used.

The electric fuel pump is composed of a pump body, a DC motor and a shell. Its basic working principle is that after the DC motor is energized, the rotor in the pump housing is driven to rotate at a high speed. The cut surface at the lower end of the rotor shaft is combined with the cut surface of the inner hole of the impeller, so that when the rotor rotates, the impeller is driven by the rotor shaft to rotate in the same direction. During the high-speed rotation of the impeller, vacuum low pressure is caused at the oil inlet, and the filtered fuel is sucked from the oil inlet of the pump cover. The sucked fuel is pressurized by the fuel pump impeller and enters the pump housing and then passes through the oil outlet pressure. To provide fuel with a certain pressure for the fuel system. The structure of the DC motor includes a permanent magnet fixed on the inner wall of the pump casing, a rotor capable of generating magnetic torque after being energized, and a graphite carbon brush assembly installed on the upper end of the pump casing. The carbon brush is in elastic contact with the commutator on the armature rotor, and its lead wire is connected to the plug-in wiring electrode of the shell. The outer ends of the electric fuel pump casing are crimped and riveted to become a non-detachable assembly.