Patent ID: 9678035
Date: 2017-06-13
CPC Classifications: G01N

Claim:
1. A hydrocarbon gas sensor that has a sensor element formed of an oxygen-ion conductive solid electrolyte and identifies a concentration of a hydrocarbon gas component of a measurement gas based on a current flowing through said solid electrolyte when said hydrocarbon gas component is burned, said hydrocarbon gas sensor comprising: first diffusion control means in communication with the outside for applying a first diffusion resistance to said measurement gas; a first internal space that is in communication with said first diffusion control means, into which said measurement gas is introduced with said first diffusion resistance from said outside; second diffusion control means in communication with said first internal space for applying a second diffusion resistance to said measurement gas; a second internal space that is in communication with said second diffusion control means, into which the measurement gas is introduced with said second diffusion resistance from said first internal space; third diffusion control means for applying a third diffusion resistance to said measurement gas introduced into said second internal space; a first electrochemical pumping cell formed of a first internal electrode formed to face said first internal space, a first external electrode formed on an outer surface of said sensor element, and said solid electrolyte located between said first internal electrode and said first external electrode; a second electrochemical pumping cell formed of a second internal electrode formed to face said second internal space, a second external electrode formed on the outer surface of said sensor element, and said solid electrolyte located between said second internal electrode and said second external electrode; a measuring pumping cell formed of a measuring electrode, a third external electrode, and said solid electrolyte located between said measuring electrode and said third external electrode, said measuring electrode being formed so as to come into contact with said measurement gas to which said third diffusion resistance has been applied, said third external electrode being formed on the outer surface of said sensor element; a reference gas space into which a reference gas is introduced; and a reference electrode formed to face said reference gas space, means for causing said first electrochemical pumping cell to adjust an oxygen partial pressure of said first internal space such that a hydrocarbon gas in said measurement gas is not substantially burned in said first internal space, means for causing said second electrochemical pumping cell to adjust an oxygen partial pressure of said second internal space such that non-target inflammable gas components of inflammable gas components existing in said second internal space are selectively burned, said non-target inflammable gas components being inflammable gas components including at least hydrogen or carbon monoxide and excluding said hydrocarbon, and means for causing said hydrocarbon gas sensor to burn, on a surface of said measuring electrode, all of said hydrocarbon existing in said measurement gas in contact with said measuring electrode after burning of said non-target inflammable gas components, by supplying oxygen to the surface of said measuring electrode by said measuring pumping cell, to thereby identify the concentration of said hydrocarbon gas component existing in said measurement gas based on the magnitude of a current flowing between said measuring electrode and said third external electrode or between said measuring electrode and said reference electrode.