Abstract: A carburetor having a suction passage including therein a large venturi section and a throttle valve and connected at the upstream end thereof to the discharge port of a supercharger and at the downstream end thereof to the intake manifold of an internal combustion engine. A recess is formed either in the outer circumference of the shaft of the throttle valve or in the inside wall of a through hole formed in the body of a carburetor for pivotally supporting the shaft of the throttle valve, whereby a pressure chamber is formed between the shaft of the throttle valve and the through hole. The pressure chamber communicates with part of the suction passage upstream of the venturi tubes by a first air passage, and a second air passage opening into the through hole at a position between the suction passage and the pressure chamber communicates with the suction passage at a position downstream of the throttle valve.

Abstract: Disclosed herein is an improvement in a variable venturi carburetor for an internal combustion engine which comprises a venturi portion, a float chamber, a main fuel passage communicating with the venturi portion and with the float chamber, a main fuel jet provided in the main fuel passage and a movable metering needle. A free end of the metering needle is adapted to control the size of the main fuel jet and the base portion of the metering needle is mounted to a suction piston adapted to transversely move with respect to the venturi portion in response to the condition of load on the internal combustion engine. The improvement includes provision of a bypass detouring upwardly from a portion of the main fuel passage upstream of the main fuel jet for discharging vapor of fuel, and the bypass communicates with a negative pressure passage which has an opening in the lower portion of the venturi portion and with an air passage which has an opening in the vicinity of an air horn inlet.

Abstract: In an air-to-fuel ratio adjusting system for an internal combustion engine which comprises an additional air supply passage communicating with the carburetor of an internal combustion engine at the position downstream of its throttle valve, a control valve disposed in the additional air supply passage to vary the passage area thereof, and a percolation sensor for detecting percolation phenomenon of the fuel during idling operation of the engine is provided. When the occurrence of a percolation phenomenon is determined in accordance with the output signal of the percolation sensor, the control valve is controlled in response to the output signal of an air-to-fuel ratio sensor, whereas the control valve is held in a predetermined valve position when there is no occurrence of percolation phenomenon during idling operation of the engine.

Abstract: A carburetor for applying air-fuel mixture to an internal combustion engine includes a main passage for applying air-fuel mixture and principally controlling the amount thereof.The air-to-fuel ratio of the air-fuel mixture to be supplied to the engine is detected by an air-to-fuel ratio detector mounted in an exhaust pipe of the engine, and when the detected ratio is lower than a stoichiometrically optimum air-to-fuel ratio for perfect combustion of the air-fuel mixture additional air is supplied to the main passage through a bypass passage, the amount of which is controlled by a bypass valve mounted in the bypass passage.An intake air pressure detecting device is mounted in an intake pipe of the engine, and when the detected pressure (absolute pressure) in the intake pipe becomes higher additional fuel is supplied to the main passage through an auxiliary fuel jet provided in the carburetor.