Electric fan

Abstract

An electric fan is provided, including a labyrinth structure with increased performance of preventing entry of a liquid into a receiving space to receive a stator and a rotor. A clearance is defined between an opposed wall portion of a base and an opposed wall portion of an impeller body, which are opposed to each other in an axial direction of a rotary shaft, to form a labyrinth structure. The opposed wall portion of the base and the opposed wall portions of the impeller body are shaped to form a volume expanding portion within the clearance. The volume expanding portion is constituted from a groove portion for expanding the clearance, having a volume larger than other portions within the clearance.

1 . An electric fan comprising:
 an electric motor including:
 a rotary shaft; 
 a stator including stator magnetic poles; and 
 a rotor including rotor magnetic poles and configured to rotate outside the stator, centering on the rotary shaft; 
   an impeller disposed outside the rotor, the impeller including:
 an impeller body fixed to the rotor and including an opposed wall portion; and 
 a plurality of blades fixed to the impeller body; 
   one or more bearings for supporting the rotary shaft; and   a casing including;
 a bearing holder by which the one or more bearings are held; and 
 a base including an opposed wall portion opposed to the opposed wall portion of the impeller body in an axial direction of the rotary shaft and extending in a radial direction of the rotary shaft and combined with the impeller body to define a receiving space to receive the stator and the rotor, wherein 
   a clearance is defined between the opposed wall portion of the base and the opposed wall portion of the impeller body to form a labyrinth structure for blocking entry of a liquid into the receiving space from radially outside of the rotary shaft; and   the opposed wall portion of the base and the opposed wall portion of the impeller body are shaped to form one or more volume expanding portions each having a volume larger than other portions within the clearance.   
     
     
         2 . The electric fan according to  claim 1 , wherein
 the impeller body includes:
 a fixed portion fixed to the rotor; and 
 a blade support fixed to the fixed portion and extending in the radial direction of the rotary shaft; 
   the blades are fixed to the blade support of the impeller body to suck an air from a side on which one axial end of the rotary shaft of the electric motor is located and discharge the air in the radial direction of the rotary shaft; and   the base is combined with the fixed portion.   
     
     
         3 . The electric fan according to  claim 1 , wherein
 a groove portion for expanding the clearance is formed in the opposed wall portion of the impeller body, the groove portion extending in a direction apart from the base to define a main part of the volume expanding portion.   
     
     
         4 . The electric fan according to  claim 1 , wherein
 a groove portion for expanding the clearance is formed in the opposed wall portion of the base, the groove portion extending in a direction apart from the impeller body to define a main part of the volume expanding portion.   
     
     
         5 . The electric fan according to  claim 1 , wherein
 a groove portion for expanding the clearance is formed in the opposed wall portion of the impeller body, the groove portion extending in a direction apart from the base to define a part of the volume expanding portion; and   a groove portion for expanding the clearance is formed in the opposed wall portion of the base, the groove portion extending in a direction apart from the impeller body to define the remaining part of the volume expanding portion.