| 摘要 |
PROBLEM TO BE SOLVED: To prevent a hole from being formed in a casing by wear of an inner wall.SOLUTION: The casing comprises: a first casing body 51 that has a bottomed cylindrical shape and can coaxially house an impeller 22; a suction hole 33 provided at the bottom center of the first casing body 51; and a protruding portion 55 protruding along the axial direction of the first casing body 51 from the bottom of the first casing body 51 and including a first upward slope 56 whose axial height from the bottom of the first casing body 51 is gradually increased along the rotation direction of the impeller 22. |
