GAS SENSOR CONTROLLER, GAS SENSOR SYSTEM, AND DETERIORATION DETERMINATION METHOD FOR GAS SENSOR ELEMENT

摘要

A gas sensor controller (100) controls a gas sensor element (10) which has a first pump cell (111), a second pump cell (113), and an oxygen concentration detection cell (112). The controller includes first chamber control means (51) to (53) which pumps oxygen out of or into a first measurement chamber MR1 such that a concentration voltage Vs becomes equal to a target voltage Vr; target voltage changing means S72, S75 which changes the target voltage Vr from a first target voltage Vr1 to a second target voltage Vr2; current detection means (55) which detects the magnitude of a concentration current Ip2 flowing between first electrode (145) and second electrode (147); and deterioration determination means S7 which determines the deterioration state of the gas sensor element from a change which occurs in the concentration current Ip2 due to the change in the target voltage Vr.

主权项

1. A gas sensor controller for controlling a gas sensor element having a first measurement chamber into which an external object gas is introduced and a second measurement chamber which communicates with the first measurement chamber and into which a first chamber gas within the first measurement chamber is introduced, the gas sensor element comprising:
a first pump cell which is formed of a first solid electrolyte body and which pumps oxygen out of the first chamber gas within the first measurement chamber or pumps oxygen into the first measurement chamber; a second pump cell which is formed of a second solid electrolyte body and which has first and second electrodes formed on the second solid electrolyte body such that the first electrode is located in the second measurement chamber and the second electrode is located outside the second measurement chamber; and an oxygen concentration detection cell which is formed of a third solid electrolyte body and which has detection and reference electrodes formed on the third solid electrolyte body such that the detection electrode is located in the first measurement chamber and the reference electrode is exposed to an atmosphere having a reference oxygen concentration, wherein the gas sensor controller comprises: first chamber control means for pumping oxygen out of the first measurement chamber or pumping oxygen into the first measurement chamber by operating the first pump cell such that a concentration voltage generated between the detection electrode and the reference electrode of the oxygen concentration detection cell becomes equal to a target voltage; target voltage changing means for changing the target voltage from a first target voltage to a second target voltage different from the first target voltage; current detection means for detecting the magnitude of a concentration current which flows between the first electrode and the second electrode in accordance with the concentration of oxygen molecules and oxygen-containing gas molecules having a dissociation voltage higher than that of oxygen molecules, the oxygen molecules and the oxygen-containing gas molecules being contained in a second chamber gas within the second measurement chamber; and deterioration determination means for determining a deterioration state of the gas sensor element from a change which occurs in the concentration current as a result of the target voltage being changed by the target voltage changing means.