| 摘要 |
PROBLEM TO BE SOLVED: To shorten the self-priming time of bathwater and reduce the noise to attain the more compact size of a pump and the improvement in convenience of a washing machine by arranging a return hole of self-priming water within a spiral passage on the circumference of an impeller, and gradually reducing the opening part of the return hole from the start end part to the terminal end part. SOLUTION: This pump has a water return hole 52a communicating with a pump runner chamber, and a lower volute (passage) 52e and an upper volute (passage) 52f by the spiral of a separation chamber 52b and the outer diameter of a runner 53. The water return hole 52a is formed into a semicircular shape with a width set to about half of the volute width in the bottom surface and gradually reduced according to the rotating direction of the runner 53, and it is opened to an angle of about 60 deg. from the bottom surface. In each section A-C, the passages are formed in a spiral shape in which the passage width is gradually increased in the circumferential direction. Further, in each section C-E, the starting end width is set according to the width of the water return hole 52e, and the downstream width therefrom is gradually increased similarly. The width of the water return hole 52a is also gradually reduced so that the flow velocity in the whole passage is substantially constant.
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