Patent Publication Number: US-2011073280-A1

Title: Heat-dissipating fan having dust-proof structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a heat-dissipating fan, and more particularly to a heat-dissipating fan having a dust-proof structure in a non-contact type. 
     2. Description of the Prior Art 
     Heat-dissipating fans are widely used on electronic products to solve the heat-dissipating problems, such as a CPU, a display card, a power supply, and the like. A conventional heat-dissipating fan comprises a stator and a rotor. An oil-retaining bearing is provided in a shaft hole of a shaft on a base of the stator. The stator includes an electromagnetic coil and silicon steel sheets fixed on the shaft. The rotator has an axle inserted in the oil-retaining bearing and a permanent magnetic ring fitted on the electromagnetic coil. When the fan is turned, the magnetic field of the electromagnetic coil and the magnetic ring drives the rotor to turn around the shaft. The blades of the rotator generate an air current to expel the heat from the electronic products so as to lower the temperature. 
     Although the conventional fan has the function to dissipate heat, there are some shortcomings existed in its structure and function when in use. In particular, there are gaps between the hub of the rotor and the base of the stator and between the top of the shaft and the bottom of the hub of the rotor, so external dust may enter the fan. After a period of time, the dust or water vapor will be accumulated in the fan to influence the running and the service life of the fan. Particularly, when the dust or water vapor enters the oil-retaining bearing, the fan cannot run smoothly or may malfunction. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a heat-dissipating fan having a dust-proof structure in a non-contact type to overcome the shortcomings of the prior art. 
     According to the present invention, there is provided a heat-dissipating fan having a dust-proof structure. The fan comprises a stator and a rotor. The stator comprises a shaft and a bearing disposed in a shaft hole of the shaft. The rotor includes an axle inserted in the bearing. The axle of the rotor has an inner end connected with an axle seat. The axle seat is located in the shaft hole of the shaft. A slight gap is defined between an outer wall of the axle seat and an inner wall of the shaft hole. The outer wall of the axle seat has a plurality of guiding grooves to block external air from entering the bearing. The guiding grooves are spiral grooves or V-shaped grooves. The guiding grooves are used to expel the air along with the rotation of the rotor, achieving a dust-proof protective structure in a non-contact type to block external dust or water vapor from entering the bearing to influence the running of the bearing. The present invention can enhance the service life of the heat-dissipating fan. 
     Preferably, the guiding grooves are spiral grooves. 
     Preferably, the guiding grooves are V-shaped grooves each including a first groove and a second groove. The first groove is adapted to compress air in the bearing inward. The second groove is adapted to expel external air. The first groove and the second groove are obliquely formed on the outer wall of the axle seat and have respective distal ends interconnected. 
     Compared to the prior art, the feature of the present invention is that the inner end of the axle of the rotor is connected with the axle seat and the outer wall of the axle seat is provided with the plurality of guiding grooves. The guiding grooves are used to expel the air along with the rotation of the rotor, achieving a dust-proof protective structure in a non-contact type to block external dust or water vapor from entering the bearing to influence the running of the bearing. The present invention can enhance the service life of the heat-dissipating fan. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view showing a heat-dissipating fan according to a preferred embodiment of the present invention; 
         FIG. 2  is an enlarged view showing an axle and an axle seat having spiral grooves thereon according to the preferred embodiment of the present invention, and 
         FIG. 3  is an enlarged view showing an axle and an axle seat having V-shaped grooves thereon according to the preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. 
       FIG. 1  is a cross-sectional view showing a heat-dissipating fan according to a preferred embodiment of the present invention. The heat-dissipating fan comprises a stator  10  and a rotor  20 . The stator  10  comprises a shaft  11  and a bearing  13  disposed in a shaft hole  12  of the shaft  11 . The rotor  20  comprises an axle  21  which is inserted in the bearing  13 . 
     Particularly, the axle  21  of the rotor  20  has an inner end connected with an axle seat  22 . The axle seat  22  is located in the shaft hole  12  of the shaft  11 . A slight gap is defined between an outer wall of the axle seat  22  and an inner wall of the shaft hole  12 . The outer wall of the axle seat  22  has a plurality of guiding grooves  23  to expel the air in the bearing  13 . 
     As shown in  FIG. 2 , the guiding grooves  23  are spiral grooves. When the rotor  20  is turned at a high speed, the spiral grooves are adapted to expel the air in the shaft hole  12  of the shaft  11  to form negative pressure in the shaft hole  12 , preventing external dust or water vapor from entering the bearing  13  in the axle hole  12 . 
     As shown in  FIG. 3 , the guiding grooves  23  are V-shaped grooves each including a first groove  231  and a second groove  232 . The first groove  231  and the second groove  232  are obliquely formed on the outer wall of the axle seat  22  and have respective distal ends interconnected. The first groove  231  is used to compress the air in the shaft hole  12  inward, and the second groove  232  is used to expel external air, such that the junction of the first groove  231  and the second groove  232  forms lower pressure to block external dust or water vapor from entering the bearing  13  in the axle hole  12 . 
     The feature of the present invention is that the inner end of the axle of the rotor is connected with the axle seat and the outer wall of the axle seat is provided with the plurality of guiding grooves. The guiding grooves are used to expel the air along with the rotation of the rotor, achieving a dust-proof protective structure in a non-contact type to block external dust or water vapor from entering the bearing to influence the running of the bearing. The present invention can enhance the service life of the heat-dissipating fan. 
     Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.