| 摘要 |
PURPOSE: To provide a control device in which the time up to the activation of a sensor element by the current-carrying to a heater can be controlled substantially constant, and the excessive rise of the element temperature can be also prevented. CONSTITUTION: In an air-fuel ratio sensor having a battery element 12 having porous electrodes on both surfaces of a solid electrolytic base and a pump element 13, a micro-current icp is carried to the battery element 12 after the current-carrying to a heater 30 is started, and the activation of a sensor element is judged from the electrode-to-electrode voltage VS generated at that time. The heater voltage VH is set to 12V at the start of current-carrying, and when the time until the electrode-to- electrode voltage VS reaches a prescribed voltage VS1 is short, the applied voltage is reduced to 11V. Consequently, the time until the activation of the sensor element is judged can be made substantially constant regardless of the dispersion of the sensor. After the activation is judged, the changing state of the element temperature is monitored from the electrode-to-electrode voltage VS, and when the element temperature is changed, the heater voltage VH is increased and decreased to stabilize the element temperature. |
