化油器(carburetor)
向火花点火式发动机供给燃油和空气混合气的装置。汽车发动机用的化油器的组成通常包括燃油室、阻风门、怠速量孔、主量孔、空气节流喉管和加速泵。燃油室中的燃油量由浮子操纵的阀控制。阻风门是蝶阀，可减少吸进的空气量，当冷引擎起动时，它使富油燃料的混合气进入汽缸。引擎的温度升高後，可用手或用热响应和引擎速度响应调节器自动地逐渐打开阻风门。由於部分关闭的节流阀附近的压力下降，燃油由怠速喷口喷入吸进的空气。当节流阀进一步打开时，主喷口开始工作。空气节流喉管处形成真空，以便从主喷口吸出燃油，使之与气流混合，吸出的油量是随空气流量大小而变，所以油气比几乎是恒定的。节流阀突然打开时，加速泵将更多的燃油喷入吸进的空气中。参阅gasoline engine和venturi tube。
English version：
carburetor
Device for supplying a spark-ignition engine with a mixture of fuel and air. Carburetors for automobile engines usually contain a storage chamber for liquid fuel, a choke, an idling jet, a main jet, an air-flow restriction, and an accelerator pump. The quantity of fuel in the storage chamber is controlled by a valve actuated by a float. The choke, a butterfly valve, reduces the intake of air so that a fuel-rich charge is drawn into the cylinders when a cold engine is started. As the engine warms up, the choke is gradually opened. Reduced pressure near the partially closed throttle valve causes the fuel to flow from the idling jet into the intake air. Further opening the throttle valve activates the main fuel jet. Then the venturi-shaped air-flow restriction creates reduced pressure, drawing fuel from the main jet into the air stream at a rate related to the air flow so that a nearly constant fuel-air ratio is obtained. The accelerator pump injects fuel into the inlet air when the throttle is opened suddenly. See also gasoline engine, venturi tube.
