| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the concentration of oxygen in exhaust gas. SOLUTION: The exhaust gas sensor is equipped with first treatment means 55 and 56 for discharging oxygen from exhaust gas in the quantity proportional to an applied voltage level and lowering the concentration of oxygen in the exhaust gas to a constant concentration and allowing a current to flow in the quantity proportional to the quantity of pumped-up oxygen, a means for decomposing NOX in the treated exhaust gas into nitrogen and oxygen to calculate the concentration of NOX from the concentration of decomposed oxygen, a means for controlling a voltage level so as to bring the concentration of oxygen in the first treatment means to a constant concentration on the basis of the concentration of oxygen in the first treatment means and second detection means 55 and 58 for setting the current quantity in the first treatment means to reference quantity when the air/fuel ratio of the exhaust gas is a theoretical air/fuel ratio to detect the concentration of oxygen before treatment due to the first treatment means from the current quantity in the first treatment means. The current quantity in the first treatment means is set to reference quantity when the first treatment means detects the concentration of oxygen in the exhaust gas of the theoretical air/fuel ratio. |
