Cooling device

Abstract

A cooling device includes a fan, a heat sink, and an attaching portion arranged to attach the fan to the heat sink. The fan includes an impeller rotating about a center axis, a motor arranged to rotate the impeller, and a base portion supporting the motor. The attaching portion includes a frame surrounding a portion of the impeller opposed to the heat sink, a plurality of supports projecting from the frame to a side opposite to the heat sink, and a plurality of supporting ribs connecting the supports and the base portion to each other, arranged about the center axis, and extending from the base portion away from the center axis. Each supporting rib has a first primary surface and a second primary surface arranged opposite to the impeller. The first and second primary surfaces are inclined with respect to a plane substantially perpendicular to the center axis.

1 - 9 . (canceled) 
   
   
       10 . A cooling device comprising:
 a fan including an impeller rotatable about a center axis of the fan, a motor arranged to rotate the impeller, and a base portion arranged to support the motor, the fan creating an air flow by rotation of the impeller;   a heat sink arranged at a location which receives the air flow from the fan to be in contact with a heat source; and   an attaching portion arranged to fix the fan to the heat sink; wherein   the attaching portion includes:
 a frame surrounding at least a portion of the impeller that is opposed to the heat sink; 
 a plurality of supports projecting from the frame to a side opposite to the heat sink; and 
 a plurality of supporting ribs arranged around the center axis of the fan, which extend from the base portion away from the center axis, and which connect to the supports; 
 each of the supporting ribs includes a first primary surface opposed to the impeller and a second primary surface which is opposite to the impeller, the first primary surface and the second primary surface being inclined with respect to a plane substantially perpendicular to the center axis; and 
 in each of the first primary surface and the second primary surface, a circumferential component extending from a downstream-side end to an upstream-side end of the supporting ribs in a rotation direction of the impeller is in a direction opposite to the rotation direction of the impeller. 
   
   
   
       11 . The cooling device according to  claim 10 , wherein a cross section of each of the supporting ribs substantially perpendicular to a longitudinal direction thereof is thinner on both sides of a center in a circumferential direction than at the center. 
   
   
       12 . The cooling device according to  claim 10 , wherein a normal angle of at least one of the first primary surface and the second primary surface near the downstream-side end thereof with respect to the center axis is in a range from approximately 20° to approximately 40°, when being averaged in a radial direction substantially perpendicular to the center axis. 
   
   
       13 . The cooling device according to  claim 10 , wherein each of the supporting ribs extends in a direction opposite to the rotation direction of the impeller as it extends away from the center axis. 
   
   
       14 . The cooling device according to  claim 13 , wherein each of the supporting ribs is curved so as to be convex along the rotation direction of the impeller. 
   
   
       15 . The cooling device according to  claim 10 , wherein an upstream-side surface of each of the supports in the rotation direction of the impeller is smooth and convex. 
   
   
       16 . The cooling device according to  claim 10 , wherein an inner side surface of the frame includes, at an end the inner side surface opposite to the heat sink, an inclined surface which extends closer to the center axis as it extends closer to the heat sink. 
   
   
       17 . The cooling device according to  claim 16 , wherein the inclined surface is approximately annular around the center axis. 
   
   
       18 . The cooling device according to  claim 10 , wherein the heat sink includes a plurality of heat-dissipating fins which are arranged around the center axis and extend along the center axis.