| 摘要 |
PROBLEM TO BE SOLVED: To detect the occurrence of abnormality when a flow passage switching valve 9 becomes switching failure with a relatively simple constitution, in a vehicular exhaust system 2 for arranging a bypass passage 8 between two catalysts 6 and 7 arranged in an exhaust passage 5 of an engine 1, arranging an exhaust heat recovery device 20 in this bypass passage 8 for recovering heat of exhaust gas, and provided with the flow passage switching valve 9 switched to an exhaust heat recovery passage for making the exhaust gas flow to the downstream side catalyst 7 from the bypass passage 8 and a non-exhaust heat recovery passage for making the exhaust gas flow to the downstream side catalyst 7 from a main flow passage 5a of the exhaust passage 5. SOLUTION: A control device 3 determines that operation of the flow passage switching valve 9 is abnormal, when the exhaust gas temperature Tx detected by a gas temperature detecting means 11 is less than a threshold value To regulated in an effective temperature range for activating the downstream side catalyst 7 after this switching operation, when switched to the non-exhaust heat recovery passage from the exhaust heat recovery passage by the flow passage switching valve 9. COPYRIGHT: (C)2009,JPO&INPIT
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