carburateur

The carburateur, or carburetor in English, is a device that mixes air with a precise amount of liquid fuel for internal combustion engines. It sits in the intake system and provides the combustible air–fuel mixture that enters the engine's cylinders.

It operates by drawing air through an intake into a venturi, where the constricted air stream speeds up and lowers pressure. A float-controlled chamber supplies fuel to jets; as air pressure drops in the venturi, fuel is drawn through the main jets and atomized to mix with the air. The throttle valve regulates the total air flow and, therefore, the fuel throughput. Additional circuits—idle, enrichment for cold starting via a choke, and often an accelerator pump—meter fuel at various engine speeds and loads. Some carburetors use a vacuum-operated or sensor-controlled mechanism to change the metering with engine demand. The mixture can be adjusted by screws or calibrated jets for idle, mid-range, and high-speed operation.

Carburateurs come in several configurations, including updraft, downdraft, and side-draft layouts, as well as single-barrel and multiple-barrel designs. In modern cars, electronic fuel injection has largely replaced carburetors, due to tighter emission controls and better fuel efficiency. Today, carburetors are still used in some older vehicles, and in small engines for lawn mowers, generators, motorcycles, and go-karts. Maintenance focuses on keeping the float valve, jets, and passages clean and properly adjusted to prevent poor performance or fuel leaks.