Method of detecting inactivation of oxygen-concentration sensor in air-fuel ratio feedback control system for internal-combustion engine

Abstract

Abstract PURPOSE:To enable to judge the inactivated state of an O2-sensor with high accuracy, by increasing or decreasing the count number of a counter representing tha inactivated state of the O2-sensor according to the temperature of exhaust gas, and making judgement that the O2-sensor is in its inactivated state when the count number of the counter has reached a prescribed value. CONSTITUTION:In operation of an engine, the base injection period determined on the basis of the output signals of a crank-angle sensor 13 and a sensor 11 for detecting the absolute intake pressure is corrected by a control circuit 16 according to the output signal of an O2-sensor 14 in its activated state. In judging the activated state of the O2-sensor 14, the count number of a timer counter is decreased at a first prescribed speed V1 at the time of engine operation such as ''fuel cut'' operation and idling operation when the temperature of exhaust gas is lowered. On the other hand, at the time of engine operation other than the above when the temperature of exhaust gas is raised, the count number of the timer counter is increased at a second prescribed speed V2 (V2<V1). When the above count number has reached a predetermined value (=0), judgement is made that the O2-sensor 14 is in its inactivated state.

Inventors

• 👤 Kikuo Tomosawa
• 👤 友澤　菊雄
• 👤 Akira Kato
• 👤 彰 加藤

Bibliographic Details