| 摘要 |
PROBLEM TO BE SOLVED: To further improve blowing efficiency while further reducing noise by a simple constitution, in a centrifugal blower.SOLUTION: A casing 18 constituting a centrifugal blower 10 has an external peripheral wall 24 which is formed into a spiral shape with respect to an external peripheral side of a fan 14 which is accommodated in the center. In the external peripheral wall 24, a first range S1 formed of an expanding angle α1 which is smaller than a substantially-constant expanding angle α is arranged in a former half portion between a winding starting end 24a joined to a linear part 26 and a winding terminal end 24b being a blow-out port 28 side, and a second range S2 formed of an expanding angle α2 which is larger than the substantially-constant expanding angle α is formed at a latter half portion. Then, in the former half portion, the external peripheral wall 24 is formed in a radial inside direction compared with the case that the external peripheral wall is formed of the substantially-constant expanding angle α, and in the latter half portion, the external peripheral wall is formed while being bulged to a radial outside direction compared with the case that the external peripheral wall is formed of the expanding angle α.SELECTED DRAWING: Figure 2 |
