Cooling fan

Abstract

A cooling fan includes a base forming a central tube at a central portion thereof, a stator mounted around the central tube and a rotor rotatable relative to the stator. The central tube defines at least one engaging slot therein. The stator includes a stator core, an upper insulating frame attached to a top side of the stator core and a lower insulating frame attached to a bottom side of the stator core. The upper insulating frame forms a plurality of protrusion tabs extending inwardly from an inner circumferential surface of the upper insulating frame. The protrusion tabs extend into and engage in the at least one engaging slot to securely mount the stator core around the central tube.

1 . A cooling fan, comprising:
 a base forming a central tube at a central portion thereof, the central tube defining at least one engaging slot therein;   a stator being mounted around the central tube, the stator comprising a stator core, an upper insulating frame being attached to a top side of the stator core and a lower insulating frame being attached to a bottom side of the stator core, the upper insulating frame forming a plurality of protrusion tabs, the protrusion tabs extending inwardly from an inner circumferential surface of the upper insulating frame, the protrusion tabs extending into and engaging in the at least one engaging slot of the central tube; and   a rotor being rotatable relative to the stator.   
     
     
         2 . The cooling fan of  claim 1 , wherein each of the protrusion tabs is substantially trapezoid-shaped. 
     
     
         3 . The cooling fan of  claim 1 , wherein the stator core comprises an annular body at a central portion thereof, and each of the protrusion tabs comprises an outer end rested on the annular body of the stator core and an inner free end protruding inward beyond the annular body. 
     
     
         4 . The cooling fan of  claim 1 , wherein the at least one engaging slot comprises a plurality of spaced engaging slots evenly arranged around a circumferential direction of the central tube for receiving the protrusion tabs, respectively. 
     
     
         5 . The cooling fan of  claim 1 , wherein the at least one engaging slot is annular and defined at a top end of central tube around a circumferential surface of the central tube. 
     
     
         6 . The cooling fan of  claim 1 , wherein the protrusion tabs are evenly arranged along a circumferential direction of the upper insulating frame. 
     
     
         7 . The cooling fan of  claim 1 , wherein a chamfer is formed at a top end of the central tube, and the at least one engaging slot is defined under the chamfer. 
     
     
         8 . The cooling fan of  claim 1 , wherein the central tube comprises a fixing section and a main section located at a bottom end of the fixing section, the main section has a diameter greater than that of the fixing section, whereby a step is formed between the fixing section and the main section, and a bottom of the stator core abuts on the step. 
     
     
         9 . The cooling fan of  claim 8 , wherein the central tube is made of metal, the central tube further comprises a securing section located at a bottom end of the main section, a top flange and a bottom flange extend outwardly from top and bottom ends of the securing section, respectively, and a portion of the base extending into a space between the top and bottom flanges to engage with the securing section. 
     
     
         10 . A cooling fan comprising:
 a fan housing having a base and a tube extending upwardly from a center of the base of the fan housing;   a stator securely mounted around the central tube, having a lower insulating frame, a stator core on the lower insulating frame and an upper insulating frame on the stator core, a stator coil winding on the lower and upper insulating frame, wherein the upper insulating frame having a protruding tab extending and engaging in a slot defined in the central tube; and   a rotor rotatably mounted on the central tube.