Measurement and control of exhaust gas recirculation with an oxygen pumping device

Claim 1

An electrochemical device form measuring the percentage of exhaust gas recirculation (EGR) in an intake air and exhaust gas mixture of an internal combustion engine, said electrochemical device including: a first solid electrochemical pump cell having a first pair of opposed electrodes; a second solid electrochemical pump cell having a second pair of opposed electrodes; a supporting structure coupled to said first and second pump cells to form with them a restricted volume; an aperture for providing communication between said restricted volume and an ambient of said intake air and exhaust gas mixture; a first external circuit means coupled to said first pump cell for passing a constant current through said first pup cell so that of said first pair of opposed electrodes a first pump cell electrode inside said volume is biased negatively causing a portion of the oxygen molecules inside said volume to be pumped out by said current flowing through said first pump cell; a second external circuit means coupled to said second pump cell for applying a constant voltage across said second pump cell so that of said second pair of opposed electrodes a second pump cell electrode inside said volume is biased negatively, said constant voltage across said second pump cell being sufficient to cause substantially all of the remainder of the oxygen molecules inside said volume to be pumped out by a current flowing through said second pump cell but less than that capable of disassociating CO 2 or H 2 O molecules; and a means coupled to said second pump cell for measuring said current flowing through said second pump cell, said second pump cell current being proportional to the percentage of O 2 molecules inside said volume not pumped out by said first pump cell and also proportional to the percentage of O 2 molecules in the intake air and exhaust gas mixture.