Patent ID: 8658013

Claim:
A system for sensing the oxygen-to-carbon (O/C) ratio of a reference gas, said system comprising: a sensor comprising an oxygen pump cell having a first pump electrode and a second pump electrode disposed on opposite sides of a first solid electrolyte layer; the first pump electrode being directly exposed to the reference gas or indirectly exposed to the reference gas through a protective coating layer and the second pump electrode being exposed to an oxygen pump chamber including a first aperture providing a fluid connection to the reference gas; an emf cell having a first emf electrode and a second emf electrode disposed on opposite sides of a second solid electrolyte layer, wherein the first emf electrode comprises a material selected from the group consisting of platinum, palladium, osmium, rhodium, iridium, gold, ruthenium, and mixtures and alloys thereof, and the second emf electrode consists essentially of the same material as the first emf electrode so as to have essentially the same capability to catalyze oxygen; the first emf electrode sharing the same oxygen pump chamber as the second pump electrode and the second emf electrode being exposed to a reference chamber having a second aperture providing a fluid connection between the second emf electrode and the reference gas; wherein the reference gas comprises reformate produced by a fuel reformer fueled by an air-fuel gas mixture having an air-fuel ratio and including a reformer electronic control module; a sensor electronic control module in electrical communication with the sensor and further in communication with the reformer electronic control module; a heater disposed in thermal communication with the sensor; a temperature sensor disposed in thermal communication with the heater and in electronic communication with the sensor control module for maintaining the sensor at a desired operating temperature; and an electrical means in electrical communication with the sensor so as to receive a signal corresponding to the emf value at the emf cell and so as to control pump current to the oxygen pump cell to maintain a constant emf at the emf cell, and wherein a pump current value represents an equivalent to the air-fuel ratio of the air-fuel gas mixture.