| 摘要 |
PURPOSE:To make it possible to accurately detect an air-fuel ratio, by providing a solid electrolyte oxygen concentration cell element provided with a porous electrode and a solid electrolyte oxygen pump element to both terminal surfaces of an oxygen ion conductive solid electrolyte. CONSTITUTION:A small gap (f) is formed between the surface of an oxygen pump element 3 in the side of the porous platinum electrode layer 4 thereof and the surface of an oxygen concn. cell element 10 in the porous platinum layer 12 thereof and both elements are mutually fixed at foot parts thereof through a heat resistant insulating spacer 19 in order to be arranged in opposed relation to each other within an exhaust pipe 1. In detecting the change in a resistance value, an arbitrary reference point is provided to the middle of a max. resistance value and a min. one so as to sense a resistance value smaller or larger than said reference point. Then, when operation is performed in a fuel super-concn. region, the resistance value of a metal oxide semiconductor 17 is smaller than said reference point and the output signal corresponding to the pump current of the oxygen pump element 3 is detected on the basis of this information at this time to enable control or measurement in the fuel super-concn. region. Similarly, control and measurement in a fuel dilute region can be performed. |
