| 摘要 |
PROBLEM TO BE SOLVED: To prevent locking of a butterfly valve 1 due to deposit. SOLUTION: A position of a seal ring seat surface 7 on which a seal ring slide surface 4 of a seal ring 3 fitted and retained in a seal ring groove 2 of a butterfly valve 1 abuts (adheres) when the butterfly valve 1 is stopped at a valve full close position after engine stop is established at a position higher than a first and a second channel wall surfaces 21, 22 of a housing 5. Namely, an inner circumference projection 6 and two of first and second stepped surfaces 31, 32 for giving an appropriate height difference between the seal ring seat surface 7 of the housing 5 and the first and the second channel wall surfaces 21, 22 are provided on a part of a channel wall surface of an exhaust gas circulation path 10 in which EGR gas flows. Consequently, deposit scratched off from a section near the valve full close position by deposit scratch off action at the time of engine stop is prevented from adhering again on the butterfly valve 1, the seal ring 3 and the seal ring seat surface 7. COPYRIGHT: (C)2007,JPO&INPIT
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