Electric fan with oil-retaining structure

Abstract

An electric fan includes a fan base ( 10 ), a bearing ( 40 ), a rotor assembly ( 20 ), and an oil-retaining structure. The fan base forms a center tube ( 11 ) receiving the bearing therein. The rotor assembly includes a fan hub ( 22 ), and a pivot axle ( 23 ) joined to the fan hub. The pivot axle pivotably extends into the bearing. The oil-retaining structure can be pivoted with the rotor assembly. The oil-retaining structure defines an oil slot ( 25 ) surrounding the pivot axle. At least one oil guide rib ( 26 ) is formed in the oil slot. As the fan is operated, the lubricant oil is thrown into the oil slot, and then thrown out of the oil slot along the oil guide rib.

1 . An electric fan comprising: 
 a fan base comprising a center tube;    a bearing received in the center tube;    a rotor assembly comprising a fan hub, and a pivot axle joined to the fan hub and pivotably extending into the bearing; and    an oil-retaining structure for being pivoted with the rotor assembly, defining therein an oil slot surrounding the pivot axle, at least one oil guide rib being formed in the oil slot to guide lubricant oil thrown into the oil slot to flow out of the oil slot as the fan is operated.    
   
   
       2 . The electric fan of  claim 1 , wherein the at least one oil guide rib comprises an inclined guide surface along which the lubricant oil flows out of the oil slot.  
   
   
       3 . The electric fan of  claim 1 , wherein the at least one oil guide rib comprises a plurality of oil guide ribs evenly distributed in the oil slot to divide the oil slot into a plurality of oil spaces.  
   
   
       4 . The electric fan of  claim 1 , wherein the oil slot has a wedge-shaped cross section, and its radial width at a closed side thereof is smaller than its radial width at an open side thereof.  
   
   
       5 . The electric fan of  claim 1 , wherein the oil-retaining structure is integrally formed with the fan hub.  
   
   
       6 . The electric fan of  claim 5 , wherein the fan hub comprises a protrusion in which an end of the pivot axle is embedded, a surrounding wall is formed around the protrusion, and the oil slot is cooperatively formed between the surround wall and the protrusion.  
   
   
       7 . The electric fan of  claim 6 , wherein the at least one oil guide rib connects the protrusion with the surrounding wall in a radial direction of the fan hub.  
   
   
       8 . The electric fan of  claim 6 , wherein the center tube defines an annular inner recess for receiving the surrounding wall.  
   
   
       9 . The electric fan of  claim 1 , wherein the oil-retaining structure and the fan hub are separately formed.  
   
   
       10 . The electric fan of  claim 9 , wherein the oil-retaining structure comprises an inner wall and an outer wall cooperatively defining the oil slot therebetween.  
   
   
       11 . An oil-retaining structure for an electric fan to prevent a leakage of lubricant oil, comprising: 
 an outer wall portion located around a pivot axle of the electric fan;    an oil slot defined within the outer wall portion for receiving the lubricant oil thrown by the pivot axle as the fan is operated; and    a plurality of oil guide ribs arranged in the oil slot for guiding the lubricant oil to leave the oil slot.    
   
   
       12 . The oil-retaining structure of  claim 11 , wherein the oil slot has a wedge-shaped cross section.  
   
   
       13 . The oil-retaining structure of  claim 11 , wherein each of the oil guide ribs comprises an inclined guide surface along which the lubricant oil flows out of the oil slot.  
   
   
       14 . The oil-retaining structure of  claim 11 , further comprising an inner wall portion for being attached to the pivot axle, and the oil slot is formed between the inner wall portion and the outer wall portion.  
   
   
       15 . An electric fan comprising: 
 a fan base securely receiving a bearing and a stator assembly therein;    a rotor assembly having a fan hub, a plurality of fan blades extending radially outwardly from the fan hub and a pivot axle extending from a top wall of the fan hub and rotatably engaging with the bearing; and    an oil-retaining structure fixed to the rotor assembly, having a wedge-shaped annular slot facing downwardly toward the fan base and surrounding the pivot axle, a plurality of ribs in the oil slot thereby dividing the oil slot into a plurality of oil spaces;    wherein when the electric fan is operated, lubricating oil flows through the oil spaces.    
   
   
       16 . The electric fan of  claim 15 , wherein the oil-retaining structure is integrally formed with the fan hub.  
   
   
       17 . The electric fan of  claim 15 , wherein the oil-retaining structure and the fan hub are separately formed.  
   
   
       18 . The electric fan of  claim 16 , wherein the fan base has a tube, and the bearing is received in the tube, the oil-retaining structure having an outer wall extending into the tube.  
   
   
       19 . The electric fan of  claim 17 , wherein the fan base has a tube, and the bearing is received in the tube, the oil-retaining structure having an outer wall extending into the tube.