| 摘要 |
PROBLEM TO BE SOLVED: To measure an air-fuel ratio in a wide range of ambience with good reproducibility, high accuracy and good stability by carrying out by an air-fuel ratio operation means such operations as avoid influences of an area ruled by a resistance and calculating air-fuel ratio data. SOLUTION: When a predetermined a.c. voltage signal 14a is impressed to an oxygen concentration detection means 12 by a power source means 14, an ambience signal 12a using an output area except a rise area (area ruled by a resistance) in a current voltage characteristic of a limiting current-type oxygen sensor is generated. An air-fuel ratio operation means 16 carries out such a predetermined operation as avoids influences of the area ruled by the resistance, thereby calculating an air fuel ratio data 16a. Even when an interfacial electric resistance is changed at an interface between an electrode and a solid electrolyte of the oxygen sensor, the data are not influence by the change. The air-fuel ratio data 16a in a wide range of ambience from one with excessive air to one with excessive fuel can be generated with good reproducibility, high accuracy and good stability. |
