| 摘要 |
PROBLEM TO BE SOLVED: To facilitate any control at a minute open area by forming a valve element of a large-diameter control valve into a profile type of valve seat form. SOLUTION: A valve element 1 has one contact point to a valve seat 2 and it is formed into a profile shape as finely increasing a clearance along a valve seat diameterϕd. Therefore, when a valve element 1 is lifted, a minimal opening part between the valve seat 2 and the valve element 1 shifts as finely increasing the profile along the circular arc of a radius R1 of the valve seat 2. With this shifting, opening is controlled, and a flow gain is also controlled. When the valve seat 2 is of a projection type, an end part of the valve element 1 is formed into a recess type of a radius R3 being larger in curvature than a projection part of the projection type. With this formation, in a minute open area, an increase in a passage area to the valve opening is made to be smallness as compared with the conventional plug valve, and thus it is possible to cope with the promotion of a large diameter in the control valve.
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