What is the use of the choke valve of the automobile carburetor? What is the principle? Is there a choke on the throttle? thank you

The choke opening of carburetor is used to adjust the concentration of combustible mixture, which can control the intake air. Under the condition of constant oil supply from the main metering hole of gasoline, the less air is inhaled, the higher the concentration of mixed gas is, and vice versa. Its function is to change the power and fuel economy of the engine. There are two ways to adjust the choke: automatic and manual. When the cold car is started, the mixture concentration should be moderately increased to ensure the smooth start of the engine.

The throttle valve is used to control the intake of combustible mixture. The larger the throttle opening, the more mixed gas is inhaled, and the stronger the power generated by the engine, otherwise the power will drop. Throttle is one of the main functions of changing engine power and driving speed during driving.