Patent ID: 6576118
Filing Date: 2003-06-10
Classification: G01N

Abstract:
An air-fuel ratio detection apparatus having correction control and being operative to receive the exhaust of an internal combustion engine, comprising:a sensor element including an oxygen pump section, said pump section having a first solid electrolyte portion forming a wall that divides an exhaust exposed side from a hollow chamber into which the exhaust from the internal combustion engine is introduced from the exhaust exposed side, and including an oxygen concentration detection section, said detection section having a second solid electrolyte portion that is disposed between said hollow chamber and a source of air, said detection section being operative for outputting a detection signal corresponding to an oxygen concentration in said hollow chamber for controlling a current to be applied to said first solid electrolyte portion so that the oxygen concentration in the hollow chamber becomes a predetermined oxygen concentration, to cause the flow oxygen into/out of the hollow chamber; an air-fuel ratio detection circuit for outputting an air-fuel ratio detection value based on the current applied to the first solid electrolyte portion by said oxygen pump section; a pump current cut off circuit for cutting off a power supply to the first solid electrolyte portion by said oxygen pump section; and an air-fuel ratio detection value correction section for correcting a detection value of air-fuel ratio based on an output value from said air-fuel ratio detection circuit at a time when the power supply to the first solid electrolyte portion by said oxygen pump section is cut off by said pump current cut off circuit.