Heat dissipation fan

Abstract

An exemplary heat dissipation fan includes a fan housing 10, a bearing assembly 20 , a stator 30 and a rotor 40. The fan housing includes a base 12 and a central tube 14 extending upwardly from the base. The bearing assembly includes a bearing 23 received in the central tube, a porous wick element 24 and a locking washer 25. The stator is mounted around the central tube. The rotor includes a shaft 47 extending through a bearing hole 231 of the bearing. The locking washer is mounted around the shaft and fixed on a top end of the central tube. The locking washer, the bearing and the shaft cooperatively form an oil reservoir 50 in the top end of the central tube. The porous wick element is received in the oil reservoir and physically contacts with the bearing.

1 . A heat dissipation fan comprising:
 a fan housing comprising a base and a central tube extending upwardly from a top surface of the base;   a bearing assembly comprising a bearing, a porous wick element and a locking washer, the bearing being received in the central tube and defining a bearing hole therein;   a stator mounted around the central tube; and   a rotor comprising a shaft extending through the bearing hole of the bearing, the locking washer being mounted around the shaft and fixed on a top end of the central tube, wherein the locking washer, the bearing and the shaft cooperatively define an oil reservoir in the top end of the central tube, and the porous wick element is received in the oil reservoir and physically contacts with the bearing.   
   
   
       2 . The heat dissipation fan of  claim 1 , wherein the locking washer comprises a retaining ring extending from the top end of the central tube towards an outer surface of the shaft. 
   
   
       3 . The heat dissipation fan of  claim 2 , wherein the locking washer further comprises a cylindrical mounting portion, the retaining ring extending inwardly from a top of the mounting portion towards the shaft, an annular recess defined in a top portion of the central tube for mounting the mounting portion of the locking washer therein. 
   
   
       4 . The heat dissipation fan of  claim 3 , wherein the locking washer further comprises a cylindrical flange extending upwardly from a top surface of the retaining ring, the flange and the mounting portion being staggered to each other with a step formed on the top surface of the retaining ring above the mounting portion, a top of the central tube bended inwardly to form a pressing portion to press on the step for keeping the locking washer and the bearing in the central tube. 
   
   
       5 . The heat dissipation fan of  claim 4 , wherein the rotor further comprises a hub, the hub forming a shaft seat fixing one end of the shaft and a cylindrical protrusion extending downwardly from the hub around the shaft seat, a diameter of the flange being smaller than a diameter of the protrusion, the flange extending from the retaining ring into a chamber defined between the shaft seat and the protrusion. 
   
   
       6 . The heat dissipation fan of  claim 2 , wherein the shaft defines an annular slot in a circumference thereof, at a position corresponding to the locking washer, the retaining ring extending from the central tube into the slot. 
   
   
       7 . The heat dissipation fan of  claim 1 , wherein the porous wick element is made of a porous material and defines a plurality of pores therein. 
   
   
       8 . The heat dissipation fan of  claim 7 , wherein the bearing defines a circular cavity in a top portion thereof, the porous wick element being received in the cavity, a bottom surface and an outer side surface of the porous wick element being physically attached to a top surface and a side surface of the bearing defining the circular cavity, respectively. 
   
   
       9 . The heat dissipation fan of  claim 7 , wherein the bearing is an oil-impregnated sleeve bearing and defines a plurality of pores therein. 
   
   
       10 . The heat dissipation fan of  claim 9 , wherein the pores defined in the porous wick element have an average pore size lager than that of the pores defined in the bearing. 
   
   
       11 . The heat dissipation fan of  claim 1 , wherein the bearing assembly further comprises a magnetic unit, the magnetic unit comprising a magnet, the base of the fan housing defining a receiving concave on a bottom surface, the central tube defining a central hole for receiving the bearing therein, the receiving concave facing opposite to and being isolated from the central hole of the central tube, the magnet being received in the receiving concave. 
   
   
       12 . The heat dissipation fan of  claim 11 , wherein the magnetic unit further comprises a cup-shaped magnetic yoke enclosing the magnet therein, and a top surface of the magnet is exposed out of the magnetic yoke and faces toward a bottom of the shaft. 
   
   
       13 . A heat dissipation fan comprising:
 a fan housing comprising a base and a central tube extending upwardly from a center of the base;   a bearing received in the central tube and defining a bearing hole therein;   a stator mounted around the central tube;   a rotor comprising a shaft extending through the bearing hole of the bearing, an oil reservoir being defined in the central tube near a top end of the central tube; and   a porous wick element received in the oil reservoir and physically contacting with a top end of the bearing.   
   
   
       14 . The heat dissipation fan of  claim 13 , further comprising a locking washer mounted to the top end of the central tube, the locking washer including a retaining ring extending from the central tube towards the shaft, the oil reservoir being defined among the retaining ring, the bearing and the shaft. 
   
   
       15 . The heat dissipation fan of  claim 14 , wherein the bearing defines a cavity in a top end thereof, the porous wick element being received in the cavity, a bottom surface and an outer side surface of the porous wick element being physically attached to the bearing.