Patent attributes
A carburettor is connected into the inlet duct (48) of an internal combustion engine. The inlet duct is divided by a dividing wall (64) into a rich passage (42) and a lean passage (44). The carburettor includes a fuel chamber (4) and defines a flow duct divided by a planar partition (66) into a rich duct (30) and a lean duct (32) which communicate with the rich and lean passages, respectively. The partition (66) defines an aperture (40) in which a planar butterfly valve (20) is pivotably mounted. A number of fuel supply orifices (61, 62) communicate with the fuel chamber (4) and with the duct (30) at a position opposite to the aperture (40). The butterfly valve (20) is pivotable between an open position, in which the flow duct is substantially open and the aperture (40) is substantially closed and all of the fuel flowing out of the fuel supply orifices (61, 62) flows into the rich duct (30), and a closed position, in which the flow duct is substantially closed and the aperture (40) is substantially open and the fuel flowing out of the fuel supply orifices flows into to both the rich and lean ducts. An idle fuel supply orifice (8) is provided in the dividing wall (64) and communicates with the rich and lean passages (42, 44) and with the fuel chamber (4) and with the atmosphere. Under idling operation of the engine, an air/fuel mixture is induced into the rich and lean passages not only through one of the fuel supply orifices (61) but also through the idle fuel supply orifice (8).
