RICH/LEAN STATE DECISION APPARATUS FOR O2 SENSOR SIGNAL

摘要

PURPOSE:To obtain a stable decision output along a higher response by providing a memory means in which specified information is memorized by a sensor output signal smaller than the first reference voltage while erased by a signal larger than the second reference voltage to make a decision. CONSTITUTION:An output signal of an O2 sensor 10 is supplied into comparators 11 and 12. An FF21 is set when the sensor output voltage becomes smaller than the reference voltage VR1 and as soon as the voltage is larger than the reference voltage VR1, a decision means 14 outputs a rich signal. As the sensor output voltage further increases beyond the reference voltage VR2, the FF21 is reset and when the sensor output voltage falls below the reference voltage VR2 surpassing the peak, a lean signal is outputted immediately. In addition, before the sensor output voltage reaches the reference voltage VR2, the reference voltage VR1 gives a comparison level while the reference voltage VR2 does a comparison level when it is not below the reference voltage VR1. Thus, a stabilized decision output can be obtained along with a higher response.