| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect abnormality of a discharge state caused by deposition of soot or dew condensation on the surfaces of insulator flow passages. SOLUTION: A plurality of fluid passage structures 12 made of insulators having a plurality of insulator flow passages 13 are layered, and insulation resistance detecting terminals 21, 22 for detecting resistance values on upstream end surfaces of the insulating flow passages 13. As the deposit of soot and dew condensation is increased, the resistance values on the surfaces of the insulator flow passages 13 are lowered to deteriorate a discharge state. With focusing on the fact, the resistance values (resistance values on the upstream end surfaces of the insulating flow passages 13) between the insulation resistance detecting terminals 21, 22 are detected in a period capable of stopping the discharge before starting an engine and/or when the engine is in operation. The discharge state is determined based on the resistance values. When the engine is in operation and discharge abnormality caused by the deposit of soot is determined, an air-fuel ratio of exhaust gas is controlled to be temporarlly rich to burn off the soot deposited to the insulator flow passages 13. |
