Patent ID: 9551345
Date: 2017-01-24
CPC Classifications: F04D

Claim:
1. An axial flow fan, comprising: an impeller mounted on a rotating shaft of a rotary drive device; and a venturi casing surrounding an outer periphery of the impeller in a radial direction and including a suction port and a discharge port which face each other in an axial direction of the rotating shaft, wherein a leading edge of a rotating blade of the impeller is formed in an arc recessed in a direction opposite to a rotating direction of the impeller, and an angle where an extended line of the recessed arc of the leading edge meets another extended line of a curve of a side edge is set in an acute angle of 30 to 37 degrees in a front view such that a leading tip of the rotating blade is projected in the rotating direction, and an opening angle of a suction-side slant portion of the venturi casing relative to a longitudinal axis of the venturi casing is set in a range of 12 to 17 degrees and an opening angle of a discharge-side slant portion of the venturi casing relative to the longitudinal axis of the venturi casing is set in a range of 30 to 35 degrees.