Parkhurst & Wendel, L.L.P.
Gas sensor having a function for minimizing heater leak current
 Disclosed is a gas sensor comprising a main pumping cell including a solid electrolyte layer contacting with an external space, and an inner pumping electrode and an outer pumping electrode formed on inner and outer surfaces of the solid electrolyte layer, for pumping-processing oxygen contained in a measurement gas introduced from the external space on the basis of a control voltage applied between the electrodes; a feedback control system for adjusting the control voltage to give a predetermined level of a voltage between the inner pumping electrode and a reference electrode disposed at a reference gas-introducing space; and a heater for heating at least the main pumping cell to a predetermined temperature; wherein the outer pumping electrode is connected to a negative side lead wire of the heater. Accordingly, the control operation in the feedback control system, which is performed to constantly control the concentration of a predetermined gas component in the measurement gas by the aid of the pumping operation, is not affected by the heater leak current, the length of the heater lead wire, and the heater current (heater output). Thus, it is possible to accurately control the concentration of the predetermined gas component. 
NGK Insulators, Ltd.
G
G01N
inventional
Nobuhide Yasuhiko
Kato Hamada