Abstract: A crossflow fan includes an impeller formed by plate-like blades 42. Each blade 42 is inclined such that the outer edge 42a is located on the leading side of the inner edge 42d with respect to the rotation direction of the impeller 41. The face of each blade 42 that is located on the leading side of the rotation direction forms a positive pressure surface 42p, and a face located on the trailing side forms a negative pressure surface 42q. Notches 42b are formed at the outer edge 42a of the blade 42. The notches 42b are arranged at predetermined intervals along the rotation axis of the impeller. The bottom 42y of the notch 42b is connected to the positive pressure surface 42p at a positive pressure corner 42n and connected to the negative pressure surface 42q at a negative pressure corner 42m. The positive pressure corner 42n and the negative pressure corner 42m are both rounded.

Abstract: An impeller is provided for a blower having a blade (15), a plurality of notches (17) provided at predetermined intervals on a side edge of the blade (15), and a plurality of smooth portions (18) each provided between a pair of the notches (17). Since a transverse vortex discharged from the side edge of the blade (15), and on a large scale, is organized by vertical vortexes formed in the notches (17) on a small scale so as to be segmented into stable transverse vortexes, it becomes possible to reduce aerodynamic noise.

Abstract: In a multi-blade fan provided with a plurality of notches in a blade edge in an outer side of each impeller blade, it is possible to direct an impeller blade outlet in a portion of the notches to a circumferential direction. Also, it is possible to direct an air flow blown out of the fan to the circumferential direction. Further, it is possible to effectively increase a pressure, by setting a projection protruding along a thickness direction of the impeller blade in a rear portion of each notch, in a pressure surface of the impeller blade receiving air pressure on the basis of rotation of the multi-blade fan.

Abstract: An impeller is provided for a blower having a blade (15), a plurality of notches (17) provided at predetermined intervals on a side edge of the blade (15), and a plurality of smooth portions (18) each provided between a pair of the notches (17). Since a transverse vortex discharged from the side edge of the blade (15), and on a large scale, is organized by vertical vortexes formed in the notches (17) on a small scale so as to be segmented into stable transverse vortexes, it becomes possible to reduce aerodynamic noise.