| 摘要 |
An air-fuel ratio detection device includes a resistor, a first voltage application section, a second voltage application section, an amplification section, an A/D conversion section, and an arithmetic section. The first voltage application section applies a direct current voltage to a first end of a series circuit constituted of an air-fuel ratio sensor and the resistor. The amplification section amplifies a voltage across the resistor and outputs an amplified voltage as an output voltage. The A/D conversion section carries out an A/D conversion of the output voltage every time before the second voltage application section switches a voltage applied to a second end of the series circuit between a first voltage and a second voltage. The arithmetic section calculates a sensor current and an impedance of the air-fuel ratio sensor using two consecutive A/D conversion results by the A/D conversion section. |
