The fuel injection nozzle is a solenoid valve with solenoid coil, needle valve, spray hole and return spring. When the ECU sends a signal to the fuel injector, the solenoid coil is connected, the needle valve is sucked up, and the fuel is ejected through the gap between the needle valve and the injection hole and enters the intake manifold. The amount of fuel injection is determined by ECU according to various information, and the opening time of injection needle valve is determined. The basic fuel injection quantity is pre stored in the ECU’s ROM, which is preset by the engine’s working conditions (i.e. the rotational speed signal transmitted by the crankshaft angle sensor and the air flow signal transmitted by the air flow meter). When the engine is warmed up, started, accelerated, increased fuel supply and reduced when decelerating, the preset fuel supply quantity needs to be corrected. Timing control of fuel injection: there are generally two injection modes. The first one is simultaneous injection: in each engine working cycle, it is injected into the cylinder twice at the same time, that is, in the engine working cycle of each cylinder, the pulse signal with equal pulse width is divided into two times and sent to each fuel injection nozzle from ECU at the same time. The second is sequential injection: in one working cycle of the engine, it is injected into each cylinder in turn according to the ignition sequence. However, when the engine is started, it can supply more fuel. In one working cycle of the engine, it injects fuel to each cylinder twice at the same time. In case of deceleration or high speed operation, the oil supply of each cylinder is cut off. Control of fuel injection quantity: for the same type of EFI vehicle, the pressure of gasoline pump is constant. No matter the opening of throttle valve, the pressure of fuel injection nozzle is always constant as long as it is adjusted by fuel pressure regulator. The fuel injector is used strictly with fuel pump and fuel pressure regulator. Only with the designed pressure, can the best atomization effect be achieved, When the pressure is lower than the design pressure, the ejected oil is not foggy, but columnar, and it is not suitable to mix with air; if the pressure is too high, the oil ejected is conical in shape, which is not easy to mix, and the injection force is too large, and a lot of fuel is directly sprayed on the pipe wall, which directly affects the mixing ratio parameters. The pressure should be constant whether it is accelerating or idling. The pressure varies from vehicle to vehicle.
Post time: Aug-17-2020