Gas sensor control apparatus and method

A control apparatus for a gas sensor, the gas sensor comprising a sensor element equipped with first and second oxygen pumping cells to define first and second measurement chambers so that a gas under measurement first flows in the first measurement chamber and then flows from the first measurement chamber into the second measurement chamber, each of the first and second oxygen pumping cells having an oxygen ion conductor and a pair of electrodes arranged on the oxygen ion conductor, the control apparatus being configured to:

• drive the first oxygen pumping cell in such a manner that the first oxygen pumping cell pumps oxygen in or out of the first measurement chamber to adjust the oxygen concentration of the gas in the first measurement chamber;
• drive the second oxygen pumping cell with the application of a drive voltage between the electrodes of the second oxygen pumping cell in such a manner that the second oxygen pumping cell pumps oxygen out of the second measurement chamber to produce a flow of electric current between the electrodes of the second oxygen pumping cell in accordance with the amount of the oxygen pumped by the second oxygen pumping cell;
• determine the concentration of a specific gas in the gas under measurement based on the electric current between the electrodes of the second oxygen pumping cell;
• and
• perform specific drive control to control the amount of the oxygen pumped by the second oxygen pumping cell to a predetermined level after startup of the sensor element and before the application of the drive voltage between the electrodes of the second oxygen pumping cell.