Composition and working principle of fuel pump armature

　　 Fuel pump armature It is a device that continuously draws fuel from the fuel tank and supplies the fuel system with the specified pressure and flow rate of fuel. Based on the function of the fuel pump armature, the performance of the fuel pump armature will directly affect the performance of the engine.

　　The fuel pump armature is the "heart" of the fuel supply system of the electric injection engine. There are two arrangement methods for the fuel pump armature in the fuel supply system. One is external mounting, that is, the fuel pump is connected in series in the pipeline outside the fuel tank. The second is built-in type, that is, the fuel pump is installed in the fuel tank and immersed in gasoline, so the fuel pump is easy to heat, low noise, and long service life, so it is widely used.

　　The fuel pump armature consists of a pump body, a DC motor, and a pump housing. Its basic working principle is that the DC motor is energized to drive the rotor in the pump housing to rotate at high speed. The cross-section of the lower end of the rotor shaft is combined with the cross-section of the impeller inner hole, so that when the rotor rotates, the impeller is driven to rotate in the same direction by the rotor shaft. During the high-speed rotation of the impeller, a vacuum low pressure is generated at the oil inlet. Then, the filtered fuel is sucked in from the inlet of the pump cover, the sucked fuel is pressurized by the fuel pump impeller into the pump housing, and then pressed out through the outlet to provide a certain pressure for the fuel system. The structure of the DC motor includes a permanent magnet fixed to the inner wall of the pump housing, a rotor that can generate a magnetic torque when energized, and a graphite carbon brush assembly installed on the top of the pump housing. The carbon brush is in elastic contact with the commutator on the armature rotor, and the lead wire is connected to the plug wiring electrode of the housing. The two ends of the fuel pump armature housing are riveted with coils, forming a non-detachable component.

　　In the fuel system, the fuel pump armature is responsible for supplying fuel at a certain pressure, and its unit fuel supply time is more than 8 times the unit time consumption of the rated power of the engine. A large amount of fuel continuously returns to the fuel tank through the oil pressure regulator, the oil pressure regulator controls the oil pressure, cools the fuel pipe, and avoids air blockage.

　　Although the specific structure of the fuel pump armature varies, it is composed of parts such as a pump oil component, a permanent magnet motor, an end cover, and a housing, as well as parts such as the housing roll edge riveting. The rotor (or pump wheel) of the pump oil component is coaxial with the motor rotor. Fuel is output from the pump oil component through the motor and end cover. A motor terminal is provided on the end cover. A one-way valve is provided in the oil outlet passage of the end cover. When the engine stops, the one-way valve closes, and the fuel in the fuel pipe will not return to the oil pump, maintaining a certain residual oil pressure, which is conducive to the next quick start. In addition, an overpressure overflow valve is installed in the pump oil assembly bracket or end cover. When the fuel pipe is blocked and the system oil pressure exceeds the allowable value, it opens and overflows to relieve pressure to prevent damage to the oil pipe or oil pump.

　　Different models of fuel pump armatures mainly have different pump oil components. Pumps can be divided into two categories according to the working principle of oil elements: positive displacement pumps and fluid power pumps. Positive displacement pumps rely on changes in pump cavity volume to suck oil and pressurize oil, so they are intermittent oil supply, with large oil pressure fluctuations and vibration noise, but the working pressure is higher. Roller pumps, gear pumps, and vane pumps are all positive displacement pumps. The working pressure of the roller pump is about 200 kPa, the gear pump can reach 400 kPa, and the vane pump can have a higher working pressure. The first two pumps are used more frequently.

　　Fluid power pumps are driven by pump wheels to drive the fuel flow, and the fuel flow changes due to changes in momentum and oil pressure. It is a continuous oil pump with small pressure fluctuations, but low working pressure, suitable for occasions with large oil volume and low oil pressure. Axial flow pumps, centrifugal pumps, turbine pumps, and side groove pumps are fluid power pumps. Among them, the working pressure of axial flow pumps and side channel pumps is about 100 kPa, and the working pressure of the other two pumps is about 300 kPa. Turbine pumps and side groove pumps are used more often.