| 摘要 |
PURPOSE:To prevent exhaust composition from deteriorating right after a start by starting feedback control over an air fuel ratio when it is decided that a pump current is within a specific variation range. CONSTITUTION:A controller is provided with a sensor part which outputs a voltage corresponding to the oxygen partial pressure ratio between a measurement electrode and a reference electrode, an oxygen layer formation member which limits the diffusion amount of the oxygen partial pressure between an oxygen layer and reference gas, an oxygen sensor (a) consisting of a pump part which determines the oxygen partial pressure of the oxygen layer according to a pump current value supplied between pump electrodes, an air fuel ratio detecting means (b) which supplies a current so that the output voltage of the sensor (a) has a specific value and detects the air fuel ratio from the current value, an operation state detecting means (c) which detects the operation state of an engine, and a means (d) which decides whether or not said current value is within the specific variation range corresponding to the operation state of the engine. Then, the feedback control over the air fuel ratio is started when it is decided by the means (d) that said current value is within the specific variation range, thereby judging properly that Ip-O2 correlation after the start of the engine is obtained. |
