Axial blower

Abstract

An axial blower includes a rotating blade assembly including a plurality of blades, a motor that rotates the rotating blade assembly to generate an airflow, and a bell mouth that is a frame surrounding the rotating blade assembly from a direction perpendicular to the rotation axis of the rotating blade assembly, wherein the bell mouth has an inlet curved surface on an upstream side of the airflow, the inlet curved surface becomes narrower toward a downstream side of the airflow in the axial direction of the rotation axis, and R1/D≤0.05 is satisfied where D represents the outer diameter of the rotating blade assembly, and R1 represents the radius of curvature of the inlet curved surface.

1 . An axial blower comprising:
 a rotating blade assembly including a plurality of blades;   a motor to rotate the rotating blade assembly to generate an airflow; and   a bell mouth being a frame surrounding the rotating blade assembly from a direction perpendicular to a rotation axis of the rotating blade assembly, wherein   the bell mouth has an inlet curved surface on an upstream side of the airflow, the inlet curved surface becoming narrower toward a downstream side of the airflow in an axial direction of the rotation axis, and   0<R 1 ′/R 1 ≤0.505 is satisfied where R 1  represents a radius of curvature of the inlet curved surface and R 1 ′ represents a difference between an outer diameter of the inlet curved surface and a length obtained by doubling a distance between a position at which a tangential line at an upstream end of the inlet curved surface is perpendicular to the rotation axis and to which the inlet curved surface is extended and the rotation axis.   
     
     
         2 . The axial blower according to  claim 1 , wherein R 1 /D≤0.05 is satisfied where D represents an outer diameter of the rotating blade assembly. 
     
     
         3 . The axial blower according to  claim 1 , wherein a blade cross section of each blade at a plane along a radial direction including the rotation axis is inclined toward an upstream side of the airflow at a blade leading edge located at a front position in a rotating direction, and an inclination angle continuously changes in such a manner that the blade cross section is more inclined toward a downstream side of the airflow as the blade is closer to a blade tailing edge located at a back position in the rotating direction. 
     
     
         4 . The axial blower according to  claim 1 , wherein
 each blade has an inflection point located between an outer side and an inner side, the inflection point being a point at which a direction to which a blade cross section is convex changes, and   the blade cross section of the blade is convex to an upstream side of the airflow on an inner side of the inflection point, and convex to a downstream side of the airflow on an outer side of the inflection point.   
     
     
         5 . The axial blower according to  claim 4 , wherein
 a radius of curvature of the blade on the outer side of the inflection point gradually decreases from a blade leading edge toward a blade tailing edge, reaches a minimum value, and then gradually increases, and   a radius of curvature of the blade on the inner side of the inflection point gradually decreases from the blade leading edge toward the blade tailing edge.   
     
     
         6 . The axial blower according to  claim 2 , wherein a blade cross section of each blade at a plane along a radial direction including the rotation axis is inclined toward an upstream side of the airflow at a blade leading edge located at a front position in a rotating direction, and an inclination angle continuously changes in such a manner that the blade cross section is more inclined toward a downstream side of the airflow as the blade is closer to a blade tailing edge located at a back position in the rotating direction. 
     
     
         7 . The axial blower according to  claim 2 , wherein
 each blade has an inflection point located between an outer side and an inner side, the inflection point being a point at which a direction to which a blade cross section is convex changes, and   the blade cross section of the blade is convex to an upstream side of the airflow on an inner side of the inflection point, and convex to a downstream side of the airflow on an outer side of the inflection point.   
     
     
         8 . The axial blower according to  claim 3 , wherein
 each blade has an inflection point located between an outer side and an inner side, the inflection point being a point at which a direction to which a blade cross section is convex changes, and   the blade cross section of the blade is convex to an upstream side of the airflow on an inner side of the inflection point, and convex to a downstream side of the airflow on an outer side of the inflection point.   
     
     
         9 . The axial blower according to  claim 6 , wherein
 each blade has an inflection point located between an outer side and an inner side, the inflection point being a point at which a direction to which a blade cross section is convex changes, and   the blade cross section of the blade is convex to an upstream side of the airflow on an inner side of the inflection point, and convex to a downstream side of the airflow on an outer side of the inflection point.   
     
     
         10 . The axial blower according to  claim 7 , wherein
 a radius of curvature of the blade on the outer side of the inflection point gradually decreases from a blade leading edge toward a blade tailing edge, reaches a minimum value, and then gradually increases, and   a radius of curvature of the blade on the inner side of the inflection point gradually decreases from the blade leading edge toward the blade tailing edge.   
     
     
         11 . The axial blower according to  claim 8 , wherein
 a radius of curvature of the blade on the outer side of the inflection point gradually decreases from a blade leading edge toward a blade tailing edge, reaches a minimum value, and then gradually increases, and   a radius of curvature of the blade on the inner side of the inflection point gradually decreases from the blade leading edge toward the blade tailing edge.   
     
     
         12 . The axial blower according to  claim 9 , wherein
 a radius of curvature of the blade on the outer side of the inflection point gradually decreases from a blade leading edge toward a blade tailing edge, reaches a minimum value, and then gradually increases, and   a radius of curvature of the blade on the inner side of the inflection point gradually decreases from the blade leading edge toward the blade tailing edge.