Gas sensor and apparatus for measuring combustible gas component concentration using the same

Abstract

A gas sensor includes a first processing chamber,into which a gas under measurement is introduced through a first gas passage,a second processing chamber,into which the gas is introduced from the first processing chamber,through a second gas passage,and in which combustible gas components burn; a third gas passage,for introducing O,into the second processing chamber,under diffusion resistance; oxygen pump element,adapted to pump out O,from or pump into the first processing chamber,on the basis of an output from an oxygen-concentration sensor,which senses the oxygen concentration of the gas introduced into the second processing chamber,to thereby control the oxygen concentration of the gas; and a second oxygen pump including a second inner electrode,and a second outer electrode,formed on an oxygen-ion conductor,in such a manner as to face the interior and exterior, respectively, of the second processing chamber,and adapted to pump out O,which remains unconsumed in burning mentioned above in the second processing chamber,through application of a constant voltage between the second inner electrode,and the second outer electrode,The residual oxygen concentration of the second processing chamber,is determined on the basis of a second oxygen pump current flowing between the second inner and outer electrodes,and,whereby the concentration of combustible gas components contained in the gas under measurement is determined.