Abstract:
A heated resistive type sensor (20) for detecting the oxygen content in an exhaust gas is connected to an electronic control unit (22) for regulating the air/fuel ratio used to operate an internal combustion engine (10). The sensor (20) has a heater (70) which provides a constant thermal energy level to a titania sensing element (76) whose resistance to the flow of electrical current is directly related to the percentage of oxygen in the exhaust gas. The electrical resistance is used as a control signal to maintain the air/fuel ratio within set limits. The resistive portion consists of three resistive elements, one that senses O. sub. 2 that is made of titania - TiO. sub. 2, the other two resistors are thick film type connected in series thereto. Finally, the gas sensing layer and electrode leads attached thereto are covered by a protective glass layering to prevent contamination of the sensor element.