Air-fuel ratio control device for engine

Abstract

Abstract PURPOSE:To improve purifying performance of exhaust in a catalyst by correcting air-fuel ratio in one of the cylinder groups in accordance with an output of the third air-fuel ratio sensor provided in a common exhaust passage, in the case of an engine which performs a feedback control of the air-fuel ratio in every cylinder group divided into two parts. CONSTITUTION:The first and second O2 sensors 15, 16 are provided in exhaust passages 13, 14 of each cylinder group divided into two parts, and being based on an output of these sensors, a feedback control of each fuel injection valve 10, 11 is performed by an ECU20 in order that air-fuel ratio of each group respectively approaches the target air-fuel ratio. Here each exhaust passage 13, 14 is collected in the downstream side of the O2 sensors 15, 16, forming a common exhaust passage 17, and a catalytic converter 18 is provided interposing halfway the passage 17. While in the upstream side part of the catalytic converter 18 in the common exhaust passage 17, the third O2 sensor 19, detecting the exhaust gas from each exhaust passage 13, 14 for its air-fuel ratio deflected from the target air-fuel ratio, is provided, and the air-fuel ratio in at least one of the cylinder groups is corrected being based on an output of the third O2 sensor 19.

Inventors

• 👤 Kazuya Komatsu
• 👤 一也 小松

Bibliographic Details