Cooling fan

Abstract

A cooling fan includes a fan housing ( 10 ) having an upper tube ( 111 ) extending downwardly from a top side thereof and a lower tube ( 121 ) extending upwardly from a bottom side thereof, a ball bearing ( 20 ) being mounted in the upper tube, a sleeve bearing ( 30 ) being mounted in the lower tube, a stator ( 45 ) mounted around the lower tube, and a rotor ( 40 ). The rotor includes a hub ( 401 ) located between the ball bearing and the sleeve bearing and a shaft ( 50 ) extending through the hub. Two ends of the shaft are rotatably received in the ball bearing and the sleeve bearing, respectively.

1 . A cooling fan comprising:
 a fan housing having an upper tube extending downwardly from a top side thereof and a lower tube extending upwardly from a bottom side thereof;   a ball bearing and a sleeve bearing being mounted in the upper and lower tubes, respectively;   a stator mounted around the lower tube; and   a rotor comprising a hub located between the ball bearing and the sleeve bearing and a shaft extending through the hub, top and bottom ends of the shaft being rotatably received in the ball bearing and the sleeve bearing, respectively.   
   
   
       2 . The cooling fan of  claim 1 , wherein the housing comprises a lower portion and an upper portion facing towards each other, the lower and upper tubes being respectively formed on the lower and upper portions of the housing. 
   
   
       3 . The cooling fan of  claim 2 , wherein the top end of the shaft extends through the upper portion of the housing and defines a slot thereon, a locking ring being arranged on the upper portion of the housing and engaging into the slot of the shaft to limit movement of the shaft along an axial direction thereof. 
   
   
       4 . The cooling fan of  claim 1 , wherein a wear pad made of highly abrasion-resistant material is arranged in a bottom end of the lower tube to face and supportively engage the bottom end of the shaft. 
   
   
       5 . The cooling fan of  claim 1 , wherein a spring is arranged between the ball bearing and the hub. 
   
   
       6 . The cooling fan of  claim 5 , wherein the spring is conical-shaped, one end of the spring with a relatively small diameter abutting against an inner ring of the ball bearing, and an opposite end of the spring with a relatively large diameter abutting against the hub. 
   
   
       7 . The cooling fan of  claim 1 , wherein the lower tube defines an end opening in a top end receiving an oil retaining ring therein, and an oil buffer is defined among the shaft, the sleeve bearing, the lower tube and the oil retaining ring. 
   
   
       8 . The cooling fan of  claim 7 , wherein the shaft defines a notch in an outer surface thereof, the notch being located in the oil buffer. 
   
   
       9 . The cooling fan of  claim 7 , wherein a plurality of grooves are defined in an outer surface of the sleeve bearing and communicate with the oil buffer. 
   
   
       10 . A cooling fan comprising:
 a hub having a plurality of fan blades extending radially and outwardly from an outer periphery thereof, and a shaft extending through a central portion of the hub;   a ball bearing being arranged above the hub; and   a sleeve bearing being arranged under the hub;   wherein the ball bearing and the sleeve bearing are respectively mounted around top and bottom ends of the shaft for supporting rotation of the shaft.   
   
   
       11 . The cooling fan of  claim 10 , wherein a spring is arranged between the hub and the ball bearing, and abuts against the ball bearing and the hub. 
   
   
       12 . The cooling fan of  claim 11 , wherein the spring is conical-shaped, one end of the spring with a relatively smaller diameter abutting against an inner ring of the ball bearing, and an opposite end of the spring with a relatively larger diameter abutting against the hub. 
   
   
       13 . The cooling fan of  claim 10 , wherein the shaft defines a slot at each of the top and bottom ends for receiving a locking ring. 
   
   
       14 . The cooling fan of  claim 13 , wherein the ball bearing and the sleeve bearing are respectively received in upper and lower tubes, the top end of the shaft extending through the upper tube and the bottom end of the shaft being received in the lower tube, a wear pad being arranged in the lower tube to face and supportively engage the bottom end of the shaft. 
   
   
       15 . The cooling fan of  claim 14 , wherein the lower tube defines an end opening in a top end receiving an oil retaining ring therein, an oil buffer being defined among the shaft, the sleeve bearing, the lower tube and the oil retaining ring, the shaft defining a notch in an outer surface thereof and located in the oil buffer.