Basic Structure Of Carburetor
A simple carburetor consists of upper, middle and lower parts. The upper part has the air inlet and float chamber, the middle part has the throat, measuring hole and nozzle, and the lower part has the throttle valve, etc. The float chamber is a rectangular container that stores gasoline from the gasoline pump. There is a float in the container that uses the height of the floating surface (oil surface) to control the amount of fuel. The oil inlet at one end of the middle nozzle is connected to the measuring hole of the float chamber, and the oil outlet at the other end is at the throat of the throat.
The throat is in the shape of a wasp’s waist, with large ends and a small middle, with the smallest cross-sectional area at the throat in the middle. When the engine starts, the piston moves downward to generate suction. When the inhaled airflow passes through the throat, it has the highest speed but the lowest static pressure. Therefore, the throat pressure is less than the atmospheric pressure. That is to say, there is a pressure difference between the throat of the throat and the float chamber, which is what people often call “vacuum degree”. The greater the pressure difference, the greater the vacuum degree. Gasoline is sprayed out from the nozzle outlet under the action of vacuum. Because the air flow rate at the throat of the throat is 25 times that of gasoline, the oil flow ejected from the nozzle is dispersed by the high-speed air flow, forming mist particles of varying sizes, that is, “atomization.” The initially atomized oil particles are mixed with air to form a “mixed gas”, which enters the combustion chamber of the cylinder through the throttle valve, intake pipe (4) and intake valve (5). Here, the opening of the throttle and the speed of the engine determine the vacuum at the throat, and the change in the opening of the throttle directly affects the proportion of the mixture. These are important reasons that affect the operation of the engine.
