Abstract: In an acceleration pump of a carburetor for an internal combustion engine including a cylinder and a piston reciprocatorily inserted in the cylinder, the piston is formed in its upper portion with a transverse bore for a stopper member to extend therethrough to be urged by a heat sensitive element to move in a direction at right angles to the direction of reciprocatory movement of the piston, so that additional fuel for acceleration can be supplied to the engine in a quantity which is accurately corrected to accommodate itself to changes in ambient temperature, by means of the heat sensitive element. The transverse bore is formed at its top wall and bottom wall with projections, and the stopper member is formed at its upper surface and lower surface with depressed portions, so as to enable the lengths of the downward and upward strokes of the piston to be controlled in accordance with changes in ambient temperature.

Abstract: An air valve type carburetor comprises a pressure transducer provided for detecting pressure in the venturi portion of the carburetor and putting out electric signals corresponding to the pressure, a passage for introducing vacuum from a suction passage for supplying air-fuel mixture into an engine downstream of a throttle valve provided in the suction passage into a suction chamber containing slidably one end of a suction piston the other end of which is disposed in the suction passage for providing the venturi portion, an electromagnetic valve provided on the passage, and a control unit. The control unit receives electrical signals from the pressure transducer, compares the electric signals with a reference valve and put out electric signals corresponding to the difference. The electromagnetic valve controls vacuum induced into the suction chamber through the passage according to signals from the control unit so that the pressure in the venturi portion will be constant.

Abstract: A carbureter for use in an internal combustion engine wherein a rotary throttle valve provided therethrough in the radial direction of the rotary shaft with a gasified fuel-air mixture passageway is provided in an air supply duct of the carburetor and the flow of mixtures of gasified fuel and air that is supplied into the engine can be controlled by the rotation of said rotary throttle valve, while said rotary throttle valve stays at a low opening degree, a bypass passageway forking from the intermediate portion of a low speed fuel passageway is made open to said gasified fuel-air mixture passageway and at the same time the upstream portion of the air supply duct of said rotary throttle valve and said gasified fuel-air mixture passageway can be communicated through an air passageway and while said rotary throttle valve is moved from the position "close" toward "open," predetermined interrelations are given to the opening positions or the sizes of port diameters of said gasified fuel-air mixture passageway, of