| 摘要 |
PROBLEM TO BE SOLVED: To prevent a design about a press contacted degree between a valve seat of a valve member and a valve seat of a valve case from becoming difficult under removal of foreign material.SOLUTION: This invention relates to a butterfly valve provided with a valve body having spherical shell type porous plate members 13a, 13b within a valve case 10 in which a valve rod 11 is rotated from its full opened valve state to a valve opening direction and a valve seat of the valve body is approached to a downstream side of the valve seat of the valve case to remove foreign materials. With such an arrangement as above, an eddy current (a') is generated in the fluid (a) flowed between the valve seat of the valve body and the valve seat of the valve case, the eddy current passes through the holes in the porous plate member and flows while peeling off the foreign materials (b) accumulated at the rear surface. Due to this flow, the foreign materials accumulated on the porous plate are smoothly removed. Upon removal of the foreign materials, due to a strong press contacted state of the valve seat of the valve body against the valve seat of the valve case, no action riding over the thickened valve seat of the valve case is carried out, so that it is possible to perform a design of a press contacted degree between the valve seat of the valve body and the valve seat of the valve case under a full-closed valve state without applying any consideration of the riding-over. |
