Patent ID: 7536999
Filing Date: 2009-05-26
Classification: F01N,F02D

Abstract:
1. An air-fuel ratio control apparatus comprising: an exhaust system including an exhaust channel with a main catalytic converter disposed in the exhaust channel, a bypass channel with a bypass catalytic converter disposed in the bypass channel, and a valve mechanism disposed between a branching section of the bypass channel and a merging section of the bypass channel on the upstream side of the main catalytic converter to selectively open and close the exhaust channel to switch a pathway for exhaust gas from the exhaust channel to the bypass channel; a first sensor arranged to detect a property indicative of an air-fuel ratio of exhaust flowing in the exhaust channel at a point downstream of the valve mechanism; and a controller configured to adjust an element temperature of the first sensor to a prescribed temperature or less during a prescribed interval of time from when the valve mechanism is switched from a closed state to an open state.