Air/fuel ratio control device for combustion engine

• Main Authors: KATO NAOTO, KAMOTO AKIRA, KATAYAMA AKIHIRO, NAGAI TOSHINARI
• Format: Patent
• Language: English; Korean
• Published: 13.04.2002
• Edition: 7
• Subjects: BLASTING; COMBUSTION ENGINES; CONTROLLING COMBUSTION ENGINES; ENGINE PLANTS IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNALCOMBUSTION ENGINES; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES ORENGINES IN GENERAL; HEATING; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS; LIGHTING; MACHINES OR ENGINES IN GENERAL; MECHANICAL ENGINEERING; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; STEAM ENGINES; TRANSPORTING; WEAPONS

PURPOSE: An air fuel ratio control apparatus of an internal combustion engine is provided to keep purification performance of an exhaust purifying catalyst high and to implement stable control of air fuel ratio. CONSTITUTION: An air-fuel ratio control apparatus of an internal combustion engine is provided with oxygen storage amount estimating means for estimating an oxygen storage amount of an exhaust purifying catalyst and air-fuel ratio control means for controlling an air-fuel ratio, based on the oxygen storage amount. An upper threshold and a lower threshold are set for the oxygen storage amount. The air-fuel ratio control means controls the air-fuel ratio to a rich region when the oxygen storage amount is larger than the upper threshold, and controls the air-fuel ratio to a lean region when the oxygen storage amount is smaller than the lower threshold. Since the control makes the oxygen storage amount vary between the upper threshold and the lower threshold (within a predetermined range), activation of the exhaust purifying catalyst is promoted, the purification performance of the exhaust purifying catalyst is kept high, and stable control of air-fuel ratio is performed. 본 발명의 내연 기관의 공연비 제어 장치는 배기 정화 촉매의 산소 흡수량을 추정하는 산소 흡수량 추정 수단과, 산소 흡수량에 근거하여 제어 공연비를 제어하는 공연비 제어 수단을 구비하고 있다. 그리고, 산소 흡수량에 대하여 상측 임계치 및 하측 임계치가 설정되어 있고, 공연비 제어 수단은 산소 흡수량이 상측 임계치보다 클 때는 공연비를 농후한(rich) 측으로 제어하고, 하측 임계치보다도 작을 때는 공연비를 희박한(lean) 측으로 제어한다. 이렇게 함으로써, 산소 흡수량이 상측 임계치와 하측 임계치의 사이(소정 범위 내)에서 변동하기 때문에, 배기 정화 촉매의 활성화가 촉진되어, 배기 정화 촉매의 정화 성능을 높게 유지할 수 있는 동시에, 안정적인 공연비 제어를 행할 수 있다.