AIR/FUEL RATIO SENSOR

PURPOSE:To elevate the output characteristic of an air/fuel ratio sensor, by covering an adsorption electrode with a heating member and a discharge electrode with a heat shielding material through a gas diffusion path to lessen the temperature dependence of a cell attributed to external environment. CONSTITUTION:An adsorption electrode 14 is provided tight on one side of a solid electrolyte 12 such as zirconia and a discharge electrode 16 done so on the other side thereof. The discharge electrode 16 is covered with a porous heat shield plate 18 while the adsorption electrode 14 with an insulation support 22 having a heat generating body 24 therein while forming a diffusion path 20 to form a cell 10 and utilizing the cell, an air/fuel ratio sensor used for a combustor is build. Then, the induced electromotive force of the cell 10 always provides a reference voltage Es by a negative feedback control of current Ip through an amplifier 30 to detect a drop in the voltage of a resistance 34 as output signal. This can elevate the accuracy of output characteristics with a reduced temperature dependence of the threshold current value.