| 摘要 |
PURPOSE:To enable to control the air-fuel ratio exactly, by feedback controlling the air-fuel ratio on the basis of the output value of an oxygen pump type air- fuel ratio sensor constituted by an ion-conductive solid electrolyte. CONSTITUTION:An air-fuel ratio sensor 2 disposed in an exhaust pipe 1 consists of a solid electrolyte oxygen pump 6 consisting of an ion-conductive solid electrolyte (stabilized zirconia) 3 in the form of a plate having a thickness, for instance, of about 0.5mm. and having platinum electrodes 4, 5 attached to both side faces thereof and a solid electrolyte oxygen sensor 10 similarly having platinum electrodes 8, 9 attached to both side faces thereof. These-pump 6 and sensor 10 are juxtaposed by a support bed 11, for instance, with a small spacing (d) of about 0.1mm.. The output, i.e., the electromotive force (e) of the sensor 2 is applied to a mixture generating means 33 via an electronic control unit 12 which supplies pump current IP necessary for keeping the electromotive force (e) at a prescribed voltage V1, a current-voltage converter 30 which converts the current IP into a voltage level, a comparator 31 which makes comparison between the output of the converter 30 and a reference level Vref, and an integrator 22. With such an arrangement, it is enabled to control the air-fuel ratio exactly. |
