Controller for air-fuel ratio

Abstract

Abstract PURPOSE:To improve reliability on the control of air-fuel ratio by comprising an air-fuel ratio sensor of two oxygen ion conductors which constitute an oxygen pump cell and a generating cell for electromotive force, and by executing or stopping feedback control on the basis of a phase difference in a voltage and current in the oxygen pump cell. CONSTITUTION:The sensor part 11 of an oxygen sensor 10 is composed of a cell for generating electromotive force 3 an an oxygen pump cell 4, any of which is constituted of an oxygen ion conductor, and a voltage Vp applied to the oxygen pump cell 4 is controlled by a sensor control circuit 5 so as to always keep a voltage Vs at the both ends of the generating cell for electromotive force 3 constant. A voltage at the both ends of a current detecting resistance 8 through which a pump current Ip flows is detected by a differential amplifier 6 to get the virtual value of the pump current Ip, which is sent to an air-fuel ratio control circuit 15 and a phase comparator 7. A phase difference in the AC fluctuating components of the above voltage Vp and current Ip is detected by the phase comparator 7, and when the phase difference stays within a fixed range, the air-fuel ratio control circuit 15 executes the feedback control of the air-fuel ratio.

Inventors

• 👤 Shoichi Washino
• 👤 鷲野　翔一
• 👤 Ryoji Nishiyama
• 👤 亮治 西山

Bibliographic Details