ENGINE SYSTEM FOR MOTOR VEHICLE

摘要

An engine system of the invention comprises an internal combustion engine; a carburetor; an exhaust gas recirculation system; an exhaust gas treatment device; and a source of secondary air, in which there is provided a fluid network which interconnects the source of secondary air, the engine exhaust system at a position upstream of the exhaust gas treatment device and the exhaust gas recirculation system at a position upstream of an exhaust gas recirculation valve and there is also provided an air injection control valve fluidly disposed in the fluid network intermediate the source of secondary air and the exhaust gas recirculation system. The air injection control valve is adapted to selectively permit and prevent the admission of air to the exhaust gas recirculation system. A controller for the air injection control valve is also disclosed which comprises a detector that generates as an output signal a first signal responsive to urban driving conditions which are empirically determined to occur when the motor vehicle is driven in urban areas and a second signal responsive to rural driving conditions which are empirically determined to occur when the motor vehicle is driven in rural areas. The controller causes the air injection valve to permit the admission of air to the EGR system when the detector detects the rural driving conditions.