The fuel injection quantity of EFI is accurate, fuel-saving, good atomization, good combustion activity, good emission and good adaptability, and the ignition time of fuel injection quantity will automatically decrease with the elevation.
However, carburetor emissions can't support the latest standards, which costs oil and is difficult to start in winter. Improper operation may flood the spark plug, and the injection concentration can't be adjusted according to the demand, resulting in poor atomization effect and insufficient combustion.
Extended data:
A simple carburetor consists of three parts: the upper part has an air inlet and a float chamber, the middle part has a throat, a metering hole and a nozzle, and the lower part has a throttle. The float chamber is a rectangular container for storing gasoline from a gasoline pump. There is a float in the container, and the oil intake is controlled by the height (oil level) of the surface of the float. The oil inlet at one end of the middle nozzle is communicated with the metering hole in the float chamber, and the oil outlet at the other end is located at the throat of the throat.
The throat is shaped like the waist of a bee, with two big ends and a small middle, and the cross-sectional area of the middle throat is the smallest. When the engine is started, the piston descends to generate suction, and the inhaled airflow passes through the throat at the highest speed, but the static pressure is the lowest, so the throat pressure is lower than atmospheric pressure, that is to say, there is a pressure difference between the throat and the float chamber, which is often called "vacuum degree". The greater the pressure difference, the greater the vacuum degree.
Gasoline is ejected from the oil outlet of the nozzle under the action of vacuum. Because the airflow speed at the throat is 25 times that of gasoline, the oil flow ejected from the nozzle is dispersed by the high-speed airflow, forming atomized particles with different sizes, that is, "atomization".
The preliminarily atomized engine oil particles are mixed with air to form a "mixed gas", which enters the combustion chamber of the cylinder through the throttle valve, the intake pipe (4) and the intake valve (5). Here, the throttle opening and engine speed determine the vacuum degree of the throat, and the throttle opening directly affects the proportion of the mixture, which is an important reason for affecting the engine operation.
References:
Carburetor-Baidu Encyclopedia