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universal fuel level gauge
Universal fuel level gauge plays an important role in the electronically controlled high-pressure common rail injection system of diesel engine. As the first "checkpoint" of the high-pressure oil circuit, it is also a common vulnerable part of the engine except the fuel injection nozzle.
However, the fuel level gauge is mostly stuck or blocked due to universal fuel quality problems. Failure is often accompanied by failure phenomena such as weak vehicle acceleration, engine speed limit, sudden flameout during driving, unstable idle speed and so on.
1. Universal fuel level gauge
The fuel level gauge, also known as the proportional valve of the fuel level gauge, is installed on the fuel inlet side of the high-pressure oil pump. Generally speaking, it is a special solenoid valve, especially because its opening can be controlled by the engine computer at any position in the stroke, so as to adjust the volume of fuel entering the plunger cavity of the high-pressure oil pump.
From the perspective of the whole high-pressure common rail injection system, the injection pressure in the common rail pipe should be kept constant and meet the set requirements during operation. The amount of fuel injected into the cylinder from the fuel injection nozzle should be equal to the fuel flow from the high-pressure oil pump.Too large or too small can not make the system stable. If the volume of fuel entering from the oil pump is larger than that ejected from the fuel injection nozzle, the pressure in the common rail pipe will continue to rise, resulting in the opening of the pressure relief valve. If it is too small, the injection pressure in the common rail pipe will continue to decrease, resulting in incomplete atomization of fuel.The fuel level gauge controls the amount of oil entering the high-pressure oil pump in real time according to the amount of oil ejected by the fuel injection nozzle and the rail pressure, so as to ensure the pressure balance in the common rail pipe.
2. Working principle of fuel level gauge
The structure of the fuel level gauge is not complex and usually consists of three parts: the shell with electromagnetic coil, valve core and plunger. When the engine is running, the ECU calculates the fuel injection quantity of the fuel injector at that time, and then combines the difference between the current rail pressure and the target rail pressure to obtain the fuel quantity that should be pressurized into the fuel pump. For the fuel level gauge, a certain amount of oil corresponds to a certain opening, that is, the current through the solenoid. The ECU forms the equivalent current through the output duty cycle signal to control the fuel level gauge to reach the set opening.
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