| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inexpensive centrifugal liquid pump using a closed-shaped impeller superior in maintainability by reducing failure, without reducing pump efficiency so much without biting-in of foreign matter, even when there is a backflow by operation such as a high head or a long distance head feed of requiring high delivery head feed pressure and operation stopping over a long period. <P>SOLUTION: The closed impeller 6 is installed in a pump casing 5, and a suction side end surface 7sf of the impeller 6 and a suction side end surface 5sf of the casing 5 carved with a foreign matter passing groove 10, are opposed via a narrow clearance G1, and a part between an inner peripheral surface of a bottom surface 5bf of a pumping flow passage 5p wider than the clearance G1 and a side plate outer peripheral surface of the impeller 6 is formed as an annular clearance G2, and is formed as a circulating flow passage 11 inclined in a downward pitch so as to guide to the outer peripheral end of the foreign matter passing groove 10 between a side plate outside surface 7o and an inside wall part 5i of the casing, and is constituted so as to suck and discharge the foreign matter to a low pressure suction flow passage SP via the foreign matter passing groove 10 from the inside of the circulating flow passage 11. <P>COPYRIGHT: (C)2012,JPO&INPIT |
