Engine air/fuel ratio control system injecting bleed air into both fuel

Abstract

An engine includes a double barreled carburetor. A sensor mounted to the exhaust system detects the concentration of a component in the exhaust. A control unit, based on a signal from the sensor, dispatches a control signal to an air bleed control valve to vary its resistance. Primary and secondary path systems lead from the outlet of the air bleed control valve and respectively supply primary bleed air into the fuel which is being supplied into the primary barrel of the carburetor and secondary bleed air into the fuel which is being supplied into the secondary barrel of the carburetor. A one way valve is fitted in the secondary path system so as to allow air flow only towards the secondary barrel, and not away therefrom. Thus, when both barrels are opened, bleed air is sucked in to the primary barrel through the primary path system, and also bleed air is sucked in to the secondary barrel through the secondary path system past the one way valve; but, when only the primary barrel is opened, bleed air is sucked in to the primary barrel through the primary path system, but no bleed air is sucked in to the secondary barrel through the secondary path system, and the one way valve prevents reverse flow of air from the secondary barrel through the secondary path system and thencefrom into the primary path system towards the primary barrel.