| 摘要 |
<p>PURPOSE: To surely monitor the conversion performance of a catalytic converter by providing a sensor element with three terminals, and determining the conversion performance of the catalytic converter based on the ratio of the values of electric resistance between two of the terminals. CONSTITUTION: A sensor element 202 having a predetermined temperature dependence characteristic is provided in a catalytic converter 200 and three terminals V, M, H are provided at the sensor element 202. The three terminals V, M, H are connected to an evaluation circuit 204, each via one connection line. Except when exhaust gas flow rate is very large, the evaluation circuit 204 performs evaluation between the terminals V, M in the front region of the catalytic converter 200 to check whether or not the catalytic converter 200 has sufficient conversion performance. If a negative evaluation is made, an alarm signal is generated. Thus, the conversion performance of the catalytic converter 200 can surely be monitored.</p> |
