| 摘要 |
PROBLEM TO BE SOLVED: To provide an impeller which well maintains the passing rate of foreign matters therethrough and realizes the high efficiency of a pump. SOLUTION: The leading edge 20a of a blade 20 formed forward in the rotating direction A extends to the radial outer side while drawing a curve from the boss 22 side to the rear. The blade 20 is a retreated blade in which the outer end 20b of the leading edge 20a is retreated rearward in the rotating direction A more than the inner end 20c on the boss 22 side. The blade 20 comprises a tip line 20e extending from the radial outer end 20b of the leading edge 20a to the trailing edge 20d of the blade 20 and a boss line 20f extending from the radial inner end 20c of the leading edge 20a to the trailing edge 20d of the blade 20 to face a shroud 21 through the outer peripheral surface of a boss 22. A sector angleθaround a rotating axis 9 between the inner end 20c and the outer end 20b of the leading edge 20a in the circumferential direction is set within 80 to 120°. The thickness of the leading edge 20a of the blade 20 is gradually increased toward the inner end 20c from the outer end 20b. COPYRIGHT: (C)2008,JPO&INPIT
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