Propeller fan

Abstract

Provided is a propeller fan, including: a boss section including a tubular wall; and a plurality of blades extending in a radiate manner from an outer peripheral surface of the tubular wall of the boss section. Secondary flow control slits are each formed between a pair of the adjacent blades on the outer peripheral surface. The slit passes through the tubular wall to communicate between an inside of the boss section and an outside of the boss section. A downstream end of the tubular wall is closed, whereas an upstream end of the tubular wall is open. In side view, the slit extends obliquely to a rotation axis of the propeller fan, and extends obliquely in the same direction as a forming direction of a blade root portion of each of the plurality of blades.

1 . A propeller fan, comprising:
 a boss comprising a tubular wall; and   a plurality of blades being provided on an outer peripheral surface of the tubular wall of the boss,   wherein a slit is formed on the outer peripheral surface,   wherein each of a plurality of the slits passes through the tubular wall to communicate between an inside of the boss and an outside of the boss,   wherein a downstream end of the tubular wall is closed, whereas an upstream end of the tubular wall is open, and   wherein, in side view, the each of the plurality of the slits extends obliquely in the same direction as a forming direction of a blade root of each of the plurality of blades.   
     
     
         2 . A propeller fan according to  claim 1 , wherein, assuming that VL 1  represents an imaginary line connecting a plurality of leading edges at positions of the blade roots of the blades, and VL 2  represents an imaginary line connecting a plurality of trailing edges, the slit is formed in a range between the imaginary line VL 1  and the imaginary line VL 2 . 
     
     
         3 . A propeller fan according to  claim 2 , wherein, assuming that VL 3  represents an imaginary line extending along an intermediate position between the pair of the adjacent blades, the slit is arranged in a forward region in a rotating direction of the propeller fan with respect to the imaginary line VL 3 . 
     
     
         4 . A propeller fan according to  claim 3 , wherein, assuming that a line positioned at equal distances from the pair of imaginary lines VL 1  and VL 2  is represented as an imaginary line VL 4 , and that when P represents an intersection point between the imaginary line VL 4  and a camber line of the forward blade of a pair of the corresponding blades in the rotating direction of the propeller fan, a line segment joining a leading edge of a corresponding backward blade and the intersection point P on the corresponding forward blade is represented as an imaginary line VL 5 , slit is arranged in a backward region in the rotating direction of the propeller fan with respect to the imaginary line VL 5 . 
     
     
         5 . A propeller fan according to  claim 1 , wherein the slit extends in parallel to a camber of the blades. 
     
     
         6 . A propeller fan according to  claim 1 , wherein the slit has a width of one tenth or less of a circumferential distance (L) between the pair of the corresponding blades. 
     
     
         7 . An air blower, comprising:
 the propeller fan of  claim 1 ;   a driving source for applying a driving force to the propeller fan; and   a casing in which the propeller fan and the driving source are housed.   
     
     
         8 . An outdoor unit, comprising:
 a heat exchanger;   the propeller fan of  claim 1 ;   a driving source for applying a driving force to the propeller fan; and   a casing in which the propeller fan, the driving source, and the heat exchanger are housed.