| 摘要 |
PROBLEM TO BE SOLVED: To provide a vertical shaft centrifugal pump that is difficult to cause poor lubrication and whose pump performance is not deteriorated.SOLUTION: The vertical shaft centrifugal pump comprises: a pump casing 1; a hollow cylindrical supporting column 4 to the lower end of which the pump casing 1 is mounted, and that is provided vertically; an impeller 2 rotating in the pump casing 1; a drive shaft 3 to the lower end of which the impeller 2 is mounted, and that is vertically inserted in the supporting column 4; and an under-liquid bearing 8 mounted to the supporting column 4 and rotatably supporting the drive shaft 3. A balance hole 31 communicated with inside of the supporting column 4 is formed on a rear casing 12 at a rear part of the impeller 2 in the pump casing 1. High-pressure liquid is introduced into the supporting column 4 from the balance hole 31 provided on the pump casing 1, and the under-liquid bearing 8 is lubricated with the high-pressure liquid. Therefore, a need of an orifice part is eliminated, and therefore, blockage of the orifice part due to foreign matters can be prevented. An internal circulation amount is not increased, and therefore, a pump performance is not reduced. |
