Abstract: A device for controlling the operation of a carburetor comprising a wax valve fitted into a bore formed in the device housing. A wax valve holder is fitted into the bore so as to surround the temperature sensitive portion of the wax valve. A cooling water passage is formed in the bore so as to surround the wax valve holder. A heat insulating space is formed between the outer wall of the temperature sensitive portion and the inner wall of the wax valve holder.

Abstract: A variable venturi-type carburetor comprising a hollow cylindrical casing and a suction piston which is movable in the casing. The casing has a support pipe extending along the axis of the suction piston. The suction piston has a piston rod which is inserted into the support pipe. A bearing sleeve, equipped with a plurality of balls, is inserted between the piston rod and the support pipe. The bearing sleeve has a plurality of connecting grooves formed on the outer circumferential wall of the sleeve and extending in the axial direction of the sleeve over the entire length thereof.

Abstract: A variable venturi-type carburetor comprising a fuel passage which is open to an intake passage. An air bleed passage is connected to the fuel passage. The carburetor comprises an air bleed control valve device for controlling the flow area of the air bleed passage. The air bleed control valve device comprises a bore formed therein, a push rod slidably inserted into the bore for controlling the flow area of the air bleed passage, and a wax valve actuating the push rod. A cooling water passage is formed in the air bleed control valve device so as to surround the air bleed passage and the wax valve.

Abstract: A variable venturi-type carburetor comprising a suction piston which has a tip face having an upstream end portion. A raised wall is formed on the inner wall of the intake passage. The upstream end portion of the suction piston cooperates with the tip edge of the raised wall to restrict the flow of air flowing within the intake passage. The upstream end portion of the suction piston has a V-shaped central portion and flat opposed end portions. The tip edge of the raised wall has a flat central portion cooperating with the V-shaped central portion of the suction piston and has opposed end portions cooperating with the flat opposed end portions of the suction piston and projecting towards the intake passage.

Abstract: A variable venturi-type carburetor comprising a suction piston which has a tip face defining a venturi portion. The tip face has a needle-mounting face at the center thereof, and a metering needle is fixed onto the needle-mounting face. The tip face also has a projecting tip face portion located upstream of the needle and projecting from the needle-mounting face towards the venturi portion. A groove, extending along the axis of the intake passage of the carburetor, is formed on the projecting tip face portion. The projecting tip face portion has a V-shaped cross-section which expands from the groove towards the venturi portion.

Abstract: A control device comprising a push rod and a wax valve actuating the push rod in response to the temperature of the cooling water of an engine. The push rod is connected to the throttle valve of the carburetor so that the degree of opening of the throttle valve becomes smaller as the temperature of the cooling water of the engine is increased. The amount of air fed into the fuel passage from the air bleed passage is controlled by the push rod so that the amount of the air is increased as the temperature of the cooling water of the engine is increased. A vacuum-operated, time-delay valve is connected between the air-bleed passage and the atmosphere and increases the amount of air fed into the fuel passage from the air-bleed passage following a brief time delay period after the engine starts.

Abstract: A variable venturi-type carburetor comprising a suction piston which has a tip face defining a venturi portion. The tip face has a projecting tip face portion located upstream of the needle and projecting toward the venturi portion. A groove, extending along the axis of the intake passage of the carburetor, is formed on the projecting tip face portion. The projecting tip face portion has a V-shaped cross-section which expands from the groove toward the venturi portion. A projection, having a V-shaped cross-section, is formed on the inner wall of the intake passage, which faces the tip face of the intake passage, which faces the tip face of the suction piston. The projection enters into the V-shaped cross-section of the projecting tip face portion of the suction piston when the amount of air fed into the cylinder of the engine is small.

Abstract: A variable venturi-type carburetor comprising a suction piston, a fuel passage, and a needle fixed onto the suction piston and extending through the fuel passage. An air bleed passage is connected to the fuel passage. During engine starting, before the engine begins to rotate by its own power, the vacuum chamber of the suction piston is open to the atmosphere and the air bleed passage is shut off. When the engine begins to rotate by its own power, the vacuum chamber of the suction piston is closed from the atmosphere. After this, the air bleed passage is gradually opened. Such control of the closing of the vacuum chamber and the opening of the air bleed passage prevents engine stall by preventing the fuel mixture from becoming excessively lean when the engine first begins to rotate on its own power and then prevents engine misfires by subsequently reducing the air-fuel ratio to a lean mixture.

Abstract: A device for adjusting the degree of opening of the throttle valve of a carburetor comprising a cam pivotally mounted on a pivot. The cam is actuated by a wax valve and rotated in accordance with an increase in the temperature of the cooling water of the engine. The cam has a cam face which is engageable with a lever connected to the throttle valve for retaining the throttle valve at a predetermined fast idling degree during engine warm-up. An auxiliary lever is pivotally mounted on the pivot. The auxiliary lever has an outer circumferential face which is engageable with the lever of the throttle valve for retaining the throttle valve at the predetermined fast idling degree after completion of engine warm-up.

Abstract: A variable venturi-type carburetor comprising a vacuum chamber, connected to a venturi portion of the carburetor, and a suction piston actuated in response to a change in vacuum in the vacuum chamber. A fuel passage is formed in the carburetor and is open to the intake passage of the carburetor. The suction piston has a needle extending through the fuel passage. An air bleed passage is connected to the fuel passage. When the level of vacuum in the intake passage becomes smaller than a predetermined level, the amount of air fed into the fuel passage from the air bleed passage is reduced, and the vacuum chamber is caused to be open to the atmosphere.