The carburetor, carburettor, or carburetter (see spelling differences), also called carb (in North America) or carbie (chiefly in Australia) for short, is a device that blends air and fuel for an internal combustion engine. It was invented by Hungarian scientists Donát Bánki and János Csonka in 1893.citation needed]
Carburetors were the usual fuel delivery method for almost all engines up until the mid-1980s, when fuel injection became the preferred method of automotive fuel delivery. A majority of motorcycles still utilize carburetors due to lower cost, but as of 2005, many new models are now being introduced with fuel injection. Carburetors are still found in small engines and in older or specialized automobiles, such as those designed for stock car racing.
When carburetors are used in small aircraft with piston engines, modifications such as the Bendix carburetter are needed to avoid fuel starvation under high g-forces.
Most carbureted (as opposed to fuel-injected) engines have a single carburetor, though some engines use multiple carburetors. Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top. This had the advantage of never "flooding" the engine, as any liquid fuel droplets would fall out of the carburetor instead of into the intake manifold; it also lent itself to use of an oil bath air cleaner, where a pool of oil below a mesh element below the carburetor is sucked up into the mesh and the air is drawn through the oil covered mesh; this was an effective system in a time when paper air filters did not exist. Beginning in the late 1930s, downdraft carburetors were the most popular type for automotive use in the United States. In Europe, the sidedraft carburettors replaced downdraft as free space in the engine bay decreased and the use of the SU-type carburetor (and similar units from other manufacturers) increased. Some small propeller-driven aircraft engines still use the updraft carburetor design, however many use more modern designs such as the Constant Velocity (CV) Bing(TM) carburetor.
The carburetor works on Bernoulli's principle: the faster air moves, the lower its pressure. The throttle (accelerator) linkage does not directly control the flow of liquid fuel. Instead, it actuates carburettor mechanisms which meter the flow of air being sucked into the engine. The speed of this flow, and therefore its pressure, determines the amount of fuel drawn into the airstream.