| 摘要 |
PURPOSE:To prevent an impeller from vibrations as well as to keep a casing and a cover from coming into contact with each other, by installing each vortex flow passage at both sides of an impeller and an interconnecting water passage interconnecting partially in a rotating shaft direction in positions proximate to an outer circumference of the impeller, while adjusting the balance of pressure in the vortext flow passage. CONSTITUTION:A casing 5 and a casing cover 7 are provided with each of annular vortex flow passages 17 and 18 having partial notches of an almost nearly semicircular section at a position opposed to plural pieces of nearly semicircular sectional grooves installed at both sides of an impeller 3, and these vortext flow passages 17 and 18 approximating an outer circumference of the impeller 3 are partially interconnected through at several spots by means of an interconnecting passage 19. With this constitution, in order to balance pressure on both sides of the impeller 3 receiving the axial pressure, the occurrence of such drawbacks that the impeller 3 vibrates in both direction due to the axial pressure, the casing 5 and its cover 7 are worn by contact with each other and impeller rotation is impeded is preventable.
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