| 摘要 |
<p>PURPOSE: To prevent the generation of a problem caused by keeping on heating an electrically heated catalyst due to the abnormality or the like of a control circuit. CONSTITUTION: The fail-safe function of forcibly cutting off power supply to the electric heater of an electrically heated catalyst(EHC) separately from a signal from an engine control system(ECM) 16, that is, a cut-off relay switch 17 switched on/off by a temperature switch 18, is interposed in the power circuit 11 of the electric heater 10. Accordingly, in the case of the ECM 16 ending in abnormality due to the influenece of noise or the like so as to continue to output current-on signals to the electric heater 10, that is, even in the case of a current being applied to the electric heater 10 outside of the operating condition of the electric heater 10, power supply to the electric heater 10 is forcibly cut off by the cut-off relay switch 17 so as to impede such a situation as to keep on heating the EHC.</p> |
