| 摘要 |
PURPOSE:To control the air-fuel ratio to any arbitrary value by a method wherein an oxygen density detector, generating a saturated current in accordance with the oxygen density in exhaust gas, is provided in the exhaust sensor of an engine, and a feedback control is effected so as to keep a threshold current at a set value. CONSTITUTION:A control circuit 300 controls a heater 110 in accordance with the detecting signal of a temperature sensor 120 to regulate the temperature of the threshold current type oxygen density detector (O2 sensor) 100 itself inbetween 700-800 deg.C. The control circuit 300 controls the O2 sensor 100 by employing an electric current supply circuit 310 so as to generate the threshold current in accordance with the density of O2, while a decision circuit 200 decides which is larger in the values of the threshold current or a voltage generated in accordance with the threshold current and a set value corresponding to the objective air-fuel ratio and provides the decision signal of binary form to the control circuit 300. The control circuit 300 effects an integral processing of the decision signal to obtain a deviation from the objective air-fuel ratio and provides a corrected control signal to a fuel amount regulating device 400, whereby the feedback control is effected so that the air-fuel ratio of mixture supplied to an engine 500 is coincided with the objective air-fuel ratio. |
