Cross flow fan

Abstract

To provide a cross flow fan that can achieve a reduction in fan input and a reduction in noise. Therefore, a negative pressure surface of each of blades of a cross flow fan has a convex part. In a cross section C, the convex part of the blade is located on an inner circumferential side of an outer edge of the blade and on an outer circumferential side of an outermost circle of virtual circles tangent to both the negative pressure surface of the blade and the positive pressure surface of the adjacent blade, the convex part and a portion of the negative pressure surface on the inner circumferential side of the convex part are connected by a straight part, and the straight part is a tangent to both the convex part and the portion of the negative pressure surface.

1 . A cross flow fan comprising:
 a plurality of support members arranged at a predetermined interval in a direction of a rotation axis, the support members being formed in the shape of a circular or ring-shaped flat plate, and   a plurality of blades provided between adjacent support members, located close to an outer circumference of the support member, and spaced apart in the circumferential direction,   each of the blades having a positive pressure surface in a rotation direction and a negative pressure surface in a counter-rotation direction, the negative pressure surface of the blade having a convex part that bulges toward the counter-rotation direction,   in a cross section perpendicular to the rotation axis,
 the convex part of the blade being located on an inner circumferential side of an outer edge of the blade concerned excluding the outer edge of the blade concerned and on an outer circumferential side of an outermost circle of virtual circles tangent to both the negative pressure surface of the blade concerned and the positive pressure surface of the blade adjacent to the counter-rotational side of the blade concerned, 
 the convex part and a portion of the negative pressure surface on the inner circumferential side of the convex part being connected by a straight part, and 
 the straight part being a tangent to both the convex part and the portion of the negative pressure surface on the inner circumferential side of the convex part. 
   
     
     
         2 . The cross flow fan according to  claim 1 , wherein
 intervals of the blades in the circumferential direction have different distances, and   in the cross section perpendicular to the rotation axis, a portion of the blade where the convex part bulges the most in the counter-rotation direction has a larger thickness in a direction perpendicular to the positive pressure surface when the blade concerned and the blade adjacent to the counter-rotational side of the blade concerned has a larger interval in the circumferential direction.   
     
     
         3 . The cross flow fan according to  claim 1 , wherein
 the intervals of the blades in the circumferential direction have different distances, and   the convex part is provided to, of the blades, the blade having an interval larger than an average value of the intervals of the blades in the circumferential direction, the interval being an interval between the blade concerned and the blade adjacent to the counter-rotational side of the blade concerned in the circumferential direction.   
     
     
         4 . The cross flow fan according to  claim 1 , wherein the convex part is provided to a portion in the direction of the rotation axis. 
     
     
         5 . The cross flow fan according to  claim 4 , wherein
 the negative pressure surface of the blade is divided into a first region and a second region alternately arranged in the direction of the rotation axis, and   the convex part is provided in the first region.   
     
     
         6 . The cross flow fan according to  claim 5 , wherein
 an inner edge portion of the blade has a thickness that gradually decreases from one side toward another side in the direction of the rotation axis, and   the first region has a larger width in the direction of the rotation axis when the inner edge portion has a smaller thickness.   
     
     
         7 . The cross flow fan according to  claim 2 , wherein
 the intervals of the blades in the circumferential direction have different distances, and   the convex part is provided to, of the blades, the blade having an interval larger than an average value of the intervals of the blades in the circumferential direction, the interval being an interval between the blade concerned and the blade adjacent to the counter-rotational side of the blade concerned in the circumferential direction.   
     
     
         8 . The cross flow fan according to  claim 2 , wherein the convex part is provided to a portion in the direction of the rotation axis. 
     
     
         9 . The cross flow fan according to  claim 3 , wherein the convex part is provided to a portion in the direction of the rotation axis. 
     
     
         10 . The cross flow fan according to  claim 7 , wherein the convex part is provided to a portion in the direction of the rotation axis. 
     
     
         11 . The cross flow fan according to  claim 8 , wherein
 the negative pressure surface of the blade is divided into a first region and a second region alternately arranged in the direction of the rotation axis, and   the convex part is provided in the first region.   
     
     
         12 . The cross flow fan according to  claim 9 , wherein
 the negative pressure surface of the blade is divided into a first region and a second region alternately arranged in the direction of the rotation axis, and   the convex part is provided in the first region.   
     
     
         13 . The cross flow fan according to  claim 10 , wherein
 the negative pressure surface of the blade is divided into a first region and a second region alternately arranged in the direction of the rotation axis, and   the convex part is provided in the first region.   
     
     
         14 . The cross flow fan according to  claim 11 , wherein
 an inner edge portion of the blade has a thickness that gradually decreases from one side toward another side in the direction of the rotation axis, and   the first region has a larger width in the direction of the rotation axis when the inner edge portion has a smaller thickness.   
     
     
         15 . The cross flow fan according to  claim 12 , wherein
 an inner edge portion of the blade has a thickness that gradually decreases from one side toward another side in the direction of the rotation axis, and   the first region has a larger width in the direction of the rotation axis when the inner edge portion has a smaller thickness.   
     
     
         16 . The cross flow fan according to  claim 13 , wherein
 an inner edge portion of the blade has a thickness that gradually decreases from one side toward another side in the direction of the rotation axis, and   the first region has a larger width in the direction of the rotation axis when the inner edge portion has a smaller thickness.