Patent ID: 6656337
Filing Date: 2003-12-02
Classification: G01N

Abstract:
A gas concentration measuring apparatus comprising:a gas concentration sensor including a gas chamber, a first cell responsive to application of a voltage to pump oxygen molecules selectively out of and into gasses admitted into the gas chamber to produce an electric current indicative of a concentration of the oxygen molecules, a second cell working to determine a concentration of a specified oxygen containing gas component contained in the gasses having passed through the first cell, and a monitor cell working to monitor a concentration of residual oxygen molecules within the gas chamber and provide an output indicative thereof; an applying voltage determining circuit looking up a predetermined voltage-to-current relation to determine a target voltage to be applied to said first cell as a function of the electric current produced by said first cell so as to preclude said first cell from decomposing the specified oxygen containing gas component; and an applying voltage controlling circuit working to apply the target voltage determined by said applying voltage determining circuit to said first cell.