| 摘要 |
<p>The present invention is intended to detect insulation failure of an EHC. In the invention, a heat generation element of the EHC is electrically insulated by an insulating member. Then, a determination as to whether insulation failure has occured is made based on an insulation resistance value of the insulating member at the time when an amount of water absorption in the insulating member is smaller than a predetermined amount of water absorption and when an amount of PM deposition in the insulating member is smaller than a predetermined amount of PM deposition, a change in the insulation resistance value of the insulating member at the time when the amount of water absorption in the insulating member decreases from an amount equal to or larger than the predetermined amount of water absorption to an amount smaller than the predetermined amount of water absorption, and a change in the insulation resistance value of the insulating member at the time when the amount of PM deposition in the insulating member decreases from an amount equal to or larger than the predetermined amount of PM deposition to an amount smaller than the predetermined amount of PM deposition.</p> |
