Axial flow fan and housing for the same

Abstract

An axial flow fan includes a housing that is formed by a process including injection molding includes a tapered surface at a frame portion thereof. One end of at least one rib is connected to an attachment portion which is a part of a stator portion of a motor portion, and the other end the rib is connected to a base portion protruding from the tapered surface. Two inclined surfaces connected to the tapered surface at the base portion and arranged in a circumferential direction with respect to a central axis are inclined such that the further a portion of the inclined surface from the central axis is, the further the portion is from a center of the rib. As a result, an air flow disturbance generated by the base portion between the rib and the frame portion is minimized, thereby reducing a noise generated due to the air flow disturbance.

1 . An axial flow fan having an injection molded housing, comprising:
 an attachment portion arranged to be provided in a stator portion of a motor having therein an impeller;   a frame portion surrounding a space in which the motor is arranged and coaxial with a central axis of the motor; and   at least one rib connecting the attachment portion and the frame portion; wherein   an inner circumferential surface of the frame portion has at least one tapered surface wherein a distance between the central axis and the tapered surface gradually decreases from a portion of the tapered surface in contact with the at least one rib to a portion of the tapered surface extending toward a rotor portion of the motor;   the frame portion includes at least one base portion to which the at least one rib is connected and which protrudes from the at least one tapered surface;   the base portion has at the portion thereof in contact with the rib a surface on either side of the at least one rib, and one of the surfaces is inclined such that the further a portion of the inclined surface from the central axis is, the further from a center line of the rib the portion of the inclined surface is.   
   
   
       2 . The axial flow fan having the housing according to  claim 1 , wherein the surfaces on either side of the at least one rib are inclined such that the further a portion of each of the inclined surface from the central axis is, the further from the center line of the rib the portion of the inclined surface is. 
   
   
       3 . The axial flow fan having the housing according to  claim 1 , wherein the further the distance between a portion of the inclined surface and the central axis is, the greater an angle generated between the portion of the inclined surface and a center line of the rib becomes. 
   
   
       4 . The axial flow fan having the housing according to  claim 1 , wherein the attachment portion is secured to the frame portion by a plurality of the ribs, and one of each pair of the surfaces disposed on a same side of each base portion of each rib includes the inclined surface. 
   
   
       5 . The axial flow fan having the housing according to  claim 1 , wherein the inclined surface is injection molded. 
   
   
       6 . The axial flow fan having the housing according to  claim 5 , wherein an outline of the frame has a shape including a straight line when viewed from an angle parallel to the central axis, a portion of the inner surface of the frame portion nearest to the straight line is a specific tapered surface at which an angle generated between the central axis and the specific tapered surface is smallest among any other portion of the inner surface of the frame portion, and the base portion is disposed on the specific tapered surface. 
   
   
       7 . The axial flow fan having the housing according to  claim 1 , wherein, a portion of the rib and a portion of the base portion are connected to one another, and the further a portion of the rib from the central axis is, the wider the rib is. 
   
   
       8 . An axial flow fan comprising:
 a motor, including:
 a rotor portion including an impeller; 
 a stator portion; and 
   an injection molded housing, including:
 an attachment portion provided in the stator portion; 
 a frame portion surrounding a space in which the motor is arranged and coaxial with a central axis of the motor; and 
 at least one rib connecting the attachment portion and the frame portion; wherein 
   an inner circumferential surface of the frame portion has at least one tapered surface wherein a distance between the central axis and the tapered surface gradually decreases from a portion of the tapered surface in contact with the at least one rib to a portion of the tapered surface extending toward a rotor portion of the motor;   the frame portion includes at least one base portion to which the at least one rib is connected and which protrudes from the at least one tapered surface;   the base portion has at the portion thereof in contact with the rib a surface on either side of the at least one rib, and one of the surfaces is inclined such that the further a portion of the inclined surface from the central axis is, the further from a center line of the rib the portion of the inclined surface is.