Axial flow fan

Abstract

An axial flow fan includes a housing, a plurality of rotor vanes that rotate inside the housing, and a plurality of sheet-like stationary vanes that are disposed below the rotor vanes and fixed to the housing. The axial flow fan includes a motor that is connected to the rotor vanes and rotates the rotor vanes about a central axis. Each stationary vane has a projecting portion projecting axially upward from a sidewall of a base portion. The projecting portion of each stationary vane has an inner side surface on the central axis side. When a stator part is attached to the housing, the outer side surface of a circuit board radially meets the inner side surfaces. The circuit board axially meets the axially upper end surface of the sidewall of the base portion.

1 . An axial flow fan comprising:
 a base portion centered on a central axis, being hollow and approximately cylindrical, and having an open end at its top end;   a circuit board arranged to axially face the base portion;   an armature arranged above the circuit board;   an impeller cup which is hollow and approximately cylindrical about the central axis and has an open end at its bottom end, the open end of the impeller cup facing the open end of the base portion;   a field-generating magnet fixed to an inner side surface of the impeller cup and arranged to generate together with the armature a torque about the central axis;   a bearing portion arranged to support the impeller cup in a rotatable manner about the central axis relative to the base portion;   a plurality of rotor vanes extending radially from an outer side surface of the impeller cup and arranged to generate an axial airflow by rotating together with the impeller cup, the rotor vanes being inclined with respect to the central axis; and   a stationary vanes extending radially from an outer side surface of the base portion and being inclined with respect to the central axis toward an opposite direction to the inclination direction of the rotor vanes, wherein   the stationary vanes project from a top of a sidewall defining the outer side surface of the base portion, and   an outer side surface of the circuit board is in radial contact with an envelope defined by connecting inner side surfaces of portions of the stationary vanes above the top of the sidewall of the base portion.   
   
   
       2 . The axial flow fan according to  claim 1 , wherein a bottom of the circuit board is in axial contact with the top of the sidewall of the base portion. 
   
   
       3 . The axial flow fan according to  claim 1 , wherein a plurality of locking portions are circumferentially arranged on the top of the sidewall of the base portion, and an outer peripheral edge of the circuit board is locked by the locking portions. 
   
   
       4 . The axial flow fan according to  claim 3 , wherein the locking portions are arranged circumferentially between the stationary vanes. 
   
   
       5 . The axial flow fan according to  claim 1 , wherein at least two of the stationary vanes include locking portions on the inner side surfaces thereof above the sidewall of the base portion, and an outer peripheral edge of the circuit board is locked by the locking portions. 
   
   
       6 . An axial flow fan comprising:
 a base portion being hollow and approximately cylindrical about a central axis, and having an open end at its top end;   a circuit board arranged to axially face the base portion;   an armature arranged above the circuit board;   an impeller cup which is hollow and approximately cylindrical about the central axis and has an open end at its bottom end, the open end of the impeller cup facing the open end of the base portion;   a field-generating magnet fixed to an inner side surface of the impeller cup and arranged to generate together with the armature a torque about the central axis;   a bearing portion arranged to support the impeller cup in a rotatable manner about the central axis relative to the base portion;   a plurality of rotor vanes extending radially from an outer side surface of the impeller cup and arranged to generate an axial airflow by rotating together with the impeller cup, the rotor vanes being inclined with respect to the central axis; and   a stationary vanes extending radially from an outer side surface of the base portion and being inclined with respect to the central axis toward an opposite direction to the inclination direction of the rotor vanes, wherein   a distance between an outer side surface of the circuit board and the central axis is approximately the same as or larger than a distance between the outer side surface of the base portion and the central axis.   
   
   
       7 . The axial flow fan according to  claim 6 , wherein the distance between the outer side surface of the circuit board and the central axis is larger than a distance of the outer side surface of the impeller cup and the central axis. 
   
   
       8 . The axial flow fan according to  claim 6 , wherein the stationary vanes project from a top of a sidewall of the base portion which defines the outer side surface of the base portion, and
 an outer peripheral edge of the circuit board is in contact with inner side surfaces of portions of the stationary vanes above the top of the sidewall of the base portion.   
   
   
       9 . The axial flow fan according to  claim 6 , wherein a bottom of the circuit board is axially spaced apart from the top of the sidewall of the base portion. 
   
   
       10 . The axial flow fan according to  claim 6 , wherein the stationary vanes project from a top of a sidewall of the base portion which defines the outer side surface of the base portion, and
 the distance between the outer side surface of the circuit board is approximately the same as or larger than a radius of an envelope defined by connecting the inner side surfaces of portions of the stationary vanes above the top of the sidewall of the base portion.   
   
   
       11 . The axial flow fan according to  claim 6 , wherein the stationary vanes project from a top of a sidewall of the base portion which defines the outer side surface of the base portion,
 at least two of the stationary vanes respectively include locking portions on the inner side surface thereof above the top of the sidewall of the base portion, and   an outer peripheral edge of the circuit board is locked by the locking portions.   
   
   
       12 . An axial flow fan comprising:
 a base portion centered on a central axis, being hollow and approximately cylindrical, and having an open end at its top end;   a circuit board arranged to axially face the base portion;   an armature arranged above the circuit board;   an impeller cup which is hollow and approximately cylindrical about the central axis and has an open end at its bottom end, the open end of the impeller cup facing the open end of the base portion;   a field-generating magnet fixed to an inner side surface of the impeller cup and arranged to generate together with the armature a torque about the central axis;   a bearing portion arranged to support the impeller cup in a rotatable manner about the central axis relative to the base portion; and   a plurality of rotor vanes extending radially from an outer side surface of the impeller cup and arranged to generate an axial airflow by rotating together with the impeller cup, wherein   a plurality of locking portions are circumferentially arranged on a top of a sidewall of the base portion which defines an outer side surface of the base portion, and   an outer peripheral edge of the circuit board is locked by the locking portions.   
   
   
       13 . The axial flow fan according to  claim 12 , further comprising a stationary vanes extending radially from the outer side surface of the base portion, wherein
 the stationary vanes and the rotor vanes are inclined with respect to the central axis toward opposite directions from each other, and   the locking portions are arranged circumferentially between the stationary vanes.