| 摘要 |
PROBLEM TO BE SOLVED: To implement the accurate control of the concentration of a gas based on a resistance of an element detected by preventing a detection value of the concentration of a gas from being abnormal during the detection of the resistance of the element. SOLUTION: An A/F signal proportional to the concentration of a gas from a gas concentration sensor such as A/F (air/fuel ratio) sensor 30 for detecting the concentration of a gas in an exhaust gas from an internal combustion engine 10 with the application of a voltage by a microcomputer 20. During the detection of the resistance of an element, a bias command signal Vr from the microcomputer 20 is converted into an analog signal Vb by a D/A converter 21 and an output voltage Vc cleared of a high frequency component is inputted into a bias control circuit 40 through an LPF 22. As a result, during the period of detecting the resistance of the element, no accurate A/F signal is outputted. This eliminates the use of a wrong A/F signal otherwise caused by holding previous A/F signals in an S/H sample holding) circuit 70 thereby enabling implementing of an accurate A/F control based on the resistance of the element detected. |
