| 摘要 |
PURPOSE:To continuously detect the concentration of oxygen ranging from the theoretical air fuel ratio to the fuel air ratio of a lean domain, by eliminating the need for troublesome operation such as changeover of taking out an output in spite of different detection principles. CONSTITUTION:An applying voltage (e) serving as a standard generating from an apparatus 6 is permitted to use a direct current or an alternating current having offset. A summing differential amplifier 9 is constituted so that an output is made to e1=e2+e and operates so that a constant applying voltage (e) is always applied to both ends of a sensor 1. A resistance for offset 10 is attached so that a detected voltage e2 does not become negative even if an electric current is turned on conversely by generating the concentration electromotive force in the oxygen sensor 1 and the whole circuit is used for a single power source. The output current of the sensor 1 is introduced into a detection resistance 7 and is detected as the voltage e2 and is amplified by a differential amplifier 8 to obtain an output voltage e0. But, in the case where the voltage e is an alternating current having offset, a low-pass filter 11 is necessary for averaging the signal voltage. |
