| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve a problem that if strongly-acid condensation water enters into an annular clearance between an outer peripheral end surface of a valve and a valve seat surface of a housing during full closing of an EGR control valve, the valve seat surface of the housing corrodes, expanding the clearance.SOLUTION: In an EGR control valve, an annular projection 71 is formed on the inner periphery of a cylindrical portion 51 that is a flow passage wall of a valve body 7 of a housing 4, and the apex of the projection 71 is used as a valve seal 69 of the housing 4. Flow passage wall surfaces 72, 73 that are recessed in a direction in which a distance (clearance) with respect to an outer peripheral end surface 18 of an EGR valve 1 is made longer than an air gap G formed between the outer peripheral end surface 18 of the EGR valve 1 and the valve seal 69 during full closing of the EGR control valve are formed on the upstream side and downstream side of the projection 71, respectively. Thus, this structure can prevent retention of strongly-acid condensation water in the air gap G that is the apex of the projection 71.</p> |
