Abstract: In a variable venturi type carburetor having a slow speed system, a fuel vapor conduit is provided, an inlet of which is open to a main fuel passage, an outlet of which is open to an intake passage. Fuel vapor occurring in the main fuel passage is carried through the fuel vapor conduit, so as not to be introduced into a slow fuel passage; thereby, the engine is rotated stably with a relatively lean air-fuel ratio.

Abstract: A variable venturi-type carburetor comprising a metering jet and at least one air-bleed bore formed on the cylindrical inner wall of the metering jet. The amount of air fed into the fuel passage of the carburetor from the air-bleed bore is controlled by an output signal from the oxygen concentration detector arranged in the exhaust manifold so that the air-fuel ratio of the mixture fed into the cylinder of the engine becomes equal to the stoichiometric air-fuel ratio. The metering needle is arranged so that it contacts the cylindrical inner wall of the metering jet and partially covers the air-bleed bore.

Abstract: In a variable venturi type carburetor having a slow speed system, a fuel vapor conduit is provided, an inlet of which is open to a main fuel passage, an outlet of which is open to an intake passage. Fuel vapor occurring in the main fuel passage is carried through the fuel vapor conduit, so as not to be introduced into a slow fuel passage; thereby, the engine is rotated stably with a relatively lean air-fuel ratio.

Abstract: An internal combustion engine having a helically-shaped intake port. When the intake manifold vacuum is in the range of about -500 through -250 mmHg, a super lean mixture is fed into the cylinders of the engine. When the intake manifold vacuum is in the range of about -250 through -100 mmHg, a fuel mixture, having the stoichiometric air-fuel ratio, is fed into the cylinders of the engine. When the intake manifold vacuum is smaller than about -100 mmHg, a rich mixture is fed into the cylinders of the engine.

Abstract: A helically-shaped intake port comprising a helical portion formed around an intake valve, and a substantially straight inlet passage portion tangentially connected to the helical portion. A bypass passage is branched off from the inlet passage portion and connected to the helical portion. A rotary valve is arranged in the bypass passage and actuated by a vacuum operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of an engine is increased beyond a predetermined value.

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 main fuel passage which is open to the intake passage of the carburetor. An air bleed passage is connected to the main fuel passage. The inlet of the air bleed passage is divided into a first passage and a second passage. A first control valve and a first jet are arranged in the first passage. A second control valve and a second jet are arranged in the second passage. The second jet has a flow area which is larger than that of the first jet. The first control valve opens the first passage only when the engine is operating under an idling state. The second control valve opens the second passage only during the cruising operation of a vehicle.

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.

Abstract: Control system for a secondary transfer port in a dual carburetor used for an internal combustion engine, which control system opens the secondary transfer port by a magnet valve connected electrically to an ignition switch during the high-load operation of the engine and closes the secondary transfer port by the magnet valve during the low-load operation of the engine.

Abstract: An exhaust gas recirculation apparatus for an internal combustion engine, which has a so-called EGR (Exhaust Gas Recirculation) valve provided with a vacuum actuator for controlling the amount of exhaust gas to be recirculated. An air introducing pipe is opened to the intake system for introducing an extra amount of air into the engine. An air control valve is provided on the air introducing pipe for stopping this introduction of the extra amount of air into the engine so that a rich air-fuel mixture can be supplied into the engine when the engine is beginning to accelerate from a low rotational speed. The vacuum actuator of the EGR valve is connected to this air introducing pipe, in order to carry out an EGR operation when a rich combustible mixture is supplied to the engine.

Abstract: A fuel evaporation control, or vapor recovery system including: a charcoal canister housing therein activated charcoal adapted to adsorb gasoline vapor from a fuel tank; a purge port leading to a canister and opening into an intake passage in such a position that a throttle valve for the carburetor may assume an upstream position and a downstream position relative to the purge port, depending on its open positions; and a valve for controlling communication between the charcoal canister and a portion of the intake manifold, which is downstream from the throttle valve, in response to the operational condition of the engine. This fuel evaporation control system allows the vapor from the fuel tank to pass into the engine during engine deceleration or when the engine is loaded over a given load level. This system, however, interrupts the supply of gasoline vapor to the engine, during engine idling or when the engine is lightly loaded.

Abstract: Disclosed is an internal combustion engine provided with a charcoal canister for absorbing evaporative fuel issued from the fuel tank and/or the float chamber of the engine. A pipe is provided between the canister and the intake manifold which is always located downstream of the throttle valve of the engine, for desorbing the absorbed evaporative fuel by the flow of purge air which flow is formed in the canister under the influence of a vacuum existing in the intake manifold. Thus, the evaporative fuel can still be introduced into the engine even if the throttle valve is in its idle position.