Abstract: A carburetor is disclosed of the variable venturi type, which has a bypass passage bypassing the throttle valve, which is controlled during starting and warming up of the engine by a piston which adjusts its flow resistance, and which is urged against the biasing action of a spring by the vacuum suction downstream of the throttle valve. The maximum open position of this piston is controlled by a heat-sensitive element which advances this position in the direction of closing the bypass passage as the engine warms up, until it is completely closed when the engine is warm. Air is fed into a supplier which supplies fuel to the carburetor inlet passage to mix with the fuel supplied thereby in an amount which varies from a minimum when the vacuum downstream of the throttle valve is minimum to a maximum when the vacuum downstream of the throttle valve is maximum. Further, the amount of fuel supplied by the fuel supplier is adjusted to be greater when the engine temperature is lower than when it is higher.

Abstract: A carburetor with a circular air valve, in which the fuel metering needle is connected to a bracket on the downstream face of the air valve.

Abstract: A variable venturi carburetor is disclosed which includes a mixture conduit having therein a throttle plate, a fixed venturi, and a vacuum sustaining plate for variably opening and closing the throat of the fixed venturi. A first fuel nozzle opens into the mixture conduit at a point on the downstream side of the vacuum sustaining plate. An electromagnetic valve is provided for controlling the amount of fuel drawn from the auxiliary fuel nozzle so that it can vary in accordance with the degree of opening of the vacuum sustaining plate but is held at a level when the degree of opening of the vacuum sustaining plate is over a predetermined level. A second fuel nozzle is provided which opens into the mixture conduit at a point on the upstream of the vacuum sustaining plate for allowing discharge of fuel in amounts proportional to vacuums appearing in the mixture conduit upstream of the vacuum sustaining plate.

Abstract: A carburetor is provided with a fuel passage which leads to a float chamber and has an air bleed opening therein, and has a nozzle leading from the fuel passage to the intake passage to discharge fuel with air bubbles into it. The nozzle is formed as a multiconduit structure along at least part of its length, in order to improve breaking up of air bubbles in the fuel, and the atomization thereof.