Patent ID: 7153097

Claim:
A centrifugal impeller comprising: a plurality of blades disposed between an impeller inlet and an impeller outlet; a plurality of fluid paths for delivering a fluid from said impeller inlet to said impeller outlet with the rotation of said centrifugal impeller, each of said fluid paths being formed between adjacent two of said blades; and a shroud and a hub for forming said fluid paths; wherein in a meridional-plane cross-section of said centrifugal impeller, a curved line of said shroud, which forms said fluid path, curves so as to project toward said hub in a region from a blade inlet to a predetermined position of said blade so that said fluid path is widened from said blade inlet to said predetermined position, and said curved line curves so as to project toward the opposite side of said hub in a region from said predetermined position of said blade to a blade outlet so that said fluid path is widened in a region downstream of said predetermined position and narrowed in the vicinity of said blade outlet.