AIR-FUEL RATIO CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device of an internal combustion engine capable of reducing the discharged amount of NOx into the atmosphere when heating a three-way conversion catalyst device quickly to a catalyst activation temperature immediately after starting the engine. SOLUTION: During the start of the engine, the combustion air-fuel ratio is set leaner than the theoretical air-fuel ratio (time t1). When only the exhaust upstream part of the three-way conversion catalyst device disposed in an engine exhaust system is determined to be heated to the catalyst activation temperature (time t2), the combustion air-fuel ratio is set richer than the theoretical air-fuel ratio to increase the temperature of the exhaust downstream part of the three-way conversion catalyst device. COPYRIGHT: (C)2007,JPO&INPIT