Patent ID: 7247001
Filing Date: 2007-07-24
Classification: F04D,F05D

Abstract:
1. An impeller having a disk-like main plate, a blade joined to said main plate, and a side plate having a suction port, characterized in that: a boss hole is formed in a central portion of said main plate for attaching a boss which engages with a pump shaft to said boss hole, wherein a the step portion is formed around the boss hole, which is formed in said main plate by drawing, said step portion constituting means for forming a gap so that when a plurality of main plates are piled on one another, said gap is formed by only contacting said step portions of adjacent main plates to each other to thereby prevent said adjacent main plates from being adhered to each other, wherein the step portion comprises a sharp angle portion on a surface of the main plate and a slant portion on an opposite surface of the main plate, and wherein the slant portion having a smaller angle than that of the sharp angle portion.