| 摘要 |
PURPOSE:To detect an air fuel ratio accurately by acceleration the gas exchange in a diffusion chamber through the operation of a pump current control means and a current supply means when the air fuel ratio varies from a leak area to a rich area or vice versa. CONSTITUTION:When the air fuel ratio varies from the rich area to the leak area and an oxygen concentration electron element M2 generates electromotive force exceeding a set value, a reverse pump current flows to an oxygen pump element M3 and oxygen in exhaust gas is sucked in the diffusion chamber. At this time, the element M2 is operated as a pump element temporarily through the operation of a current supply means M7 to suck the oxygen in the exhaust gas in the chamber M1, thereby accelerating the gas exchange nearby the electrode of the element M2 facing the chamber M1. When the air fuel ratio varies from the leak area to the rich area, on the other hand, the element M2 is operated as a pump element temporarily through the operation of the means M7 and oxygen in the chamber M1 is discharged to the exhaust gas, thereby accelerating the gas exchange nearby the electrode of the element 2 facing the chamber M11. Thus, the gas exchange in the chamber M1 is performed smoothly. |
