| 摘要 |
<p>PURPOSE: To prevent effect on the operating stability of a sensitive engine used with a catalyst to be inspected by combining an amplitude evaluation technique familiar to the operation of the engine with well-responsive frequency evaluation. CONSTITUTION: In a switching signal output 16, a sonde 13h behind a catalyst 12 indicates vibration for oxygen content at the output side of the catalyst 12. When a signal that an average value formed at preset time intervals exceeds a critical value is issued, a switch 15 is changed over so that a signal from the sonde 13h behind the catalyst 12, as an actual value controlled variable, is supplied to a controlled variable subtracter 21. At the same time, a frequency determining and evaluating device 17 is activated with the switch signal to determine the frequency of a signal for a control algorithm FR and compare it with a preset frequency and, once the frequency exceeds a critical value, an evaluation signal is set to a high level and then the catalyst 12 is instructed to be replaced.</p> |
