| 摘要 |
PURPOSE:To provide a life diagnostic device capable of judging the life of sensor without lowering the performance of an oxygen sensor element and without obstructing the continuous operation of an oxygen meter, etc. CONSTITUTION:A life diagnostic device for self-heating, limit current type oxygen sensor is provided with (a) a heater control means to switch over the temperatures of the oxygen sensor to normal operating temperatures and diagnostic operating temperatures, (b) a means to switch over the operating temperatures of the oxygen sensor from normal operating temperatures to the diagnostic operating temperatures when the output value X of the oxygen sensor detected at the normal operating temperatures is within a specified range continuously for a specified time, (c) a means to calculate the difference >>Y-X>> between the output values Y and X of the oxygen sensor at the diagnostic operating temperatures, and (d) a life diagnostic means to diagnose that the oxygen sensor is exhausted when the value of difference >>Y-X>> is over a specified limit. |
