PURPOSE: To increase ventilating efficiency by a method wherein notches are provided on the upper end surfaces of blades and annular ribs are entered into the notches to reduce airstream flowing through a clearace between them.
CONSTITUTION: The blades 11 are attached to an impeller 10. The end surfaces of the blades, which are opposing to an upper casing 12, are provided with the notches 13. The annular ribs 14 are provided on the internal surface of the upper casing 12, which is opposing to the end surfaces of the blades 11 of the impeller 10. The notches 13 and the annular ribs 14 are entered into each other and, therefore, the hydraulic resistance of a clearance 20 is increased, airstream is not caused by the resistance substantially and the ventilating efficiency may be increased.
YAMAOKA MIKIO
YAMAURA IZUMI
| JPS52153213A | 1977-12-20 | |||
| JPS5018603A | 1975-02-27 | |||
| JPS5440311A | 1979-03-29 |