| 摘要 |
PURPOSE:To easily and surely measure an air fuel ratio over a wide range with simple constitution by laminating a porous gas diffusion control layer and a gas impermeating layer on one side of a solid-state electrolyte plate equipped with two-pair of electrodes on both sides thereof and the atmospheric air is introduced to the other side. CONSTITUTION:An air fuel ratio sensor is introduced into emission gas. In the lean state of the air fuel mixture, to a porous electrode on the atmospheric side 4 is applied a positive voltage, while to an electrode 2 towards the porous gas diffusion control layer 6 with laminated gas impermeating layer 9 is applied with a negative voltage. These electrodes constitute a pair of porous electrodes constituting an oxygen pumping element 10 of the solid-state electrolyte plate 1. Oxygen ions in the element 10 are moved and the oxygen in the vicinity of the electrode 2 is pumped towards the atmosphere so that the oxygen partial pressure ratio in the discharge gas of the layer 6 is changed. This change is detected by an oxygen concentration cell element 11 formed by a pair of electrodes 3, 5 provided to a plate 1 and the air fuel ratio is measured from the supply current to the element 10 that will feed the constant detection value. The same may be said of the rich state so that the porosity ratio of the gas diffusion limiting layer can be easily controlled by a simple constitution to provide for easy and reliable control of the air fuel ratio over a wide range from the lean to the rich state. |
