Fan and manufacturing method thereof

Abstract

A fan includes a motor base, a bearing, an impeller, a stator and a magnetic element. The motor base has a bearing stand in a center portion thereof. The bearing is accommodated within the bearing stand. The impeller includes a metallic case, a hub, plural blades and a rotating shaft. The metallic case has a top surface and a sidewall. The hub is sheathed around the metallic case. The blades are disposed around an outer periphery of the hub. The rotating shaft is protruded from a center portion of the top surface and penetrated through the bearing stand, wherein no raised ring structure is formed in the top surface of the metallic case, and the rotating shaft and the metallic case are jointed together by a laser welding process. The magnetic element is disposed on an inner wall of the metallic case and aligned with the stator.

What is claimed is: 
     
         1 . A fan, comprising:
 a motor base having a bearing stand in a center portion thereof;   a bearing accommodated within said bearing stand;   an impeller comprising:
 a metallic case having a top surface and a sidewall extended axially from an outer periphery of said top surface; 
 a hub sheathed around said metallic case; 
 plural blades disposed around an outer periphery of said hub; and 
 a rotating shaft protruded from a center portion of said top surface and penetrated through said bearing stand, wherein no raised ring structure is formed in said top surface of said metallic case, and said rotating shaft and said metallic case are jointed together by a laser welding process; 
   a stator disposed around an outer periphery of said bearing stand; and   a magnetic element disposed on an inner wall of said metallic case and aligned with said stator.   
     
     
         2 . The fan according to  claim 1  wherein said top surface of said metallic case has a thickness of 0.1˜2.0 mm. 
     
     
         3 . The fan according to  claim 1  wherein an opening is formed in said center portion of said top surface of said metallic case, and said rotating shaft is inserted into said opening. 
     
     
         4 . The fan according to  claim 1  wherein said rotating shaft is made of metallic shaft. 
     
     
         5 . The fan according to  claim 1  wherein no embossed recess is formed in said rotating shaft. 
     
     
         6 . The fan according to  claim 1  wherein said blades are integrally formed with said hub. 
     
     
         7 . The fan according to  claim 1  wherein said metallic case further comprises a sub-top surface at a horizontal level lower than said top surface, wherein when said metallic case is sheathed by said hub, said sub-top surface of said metallic case is sheltered by said hub. 
     
     
         8 . The fan according to  claim 1  wherein said fan further comprises a fan frame, which is arranged at an outer portion of said fan. 
     
     
         9 . The fan according to  claim 1  wherein an overall thickness of said fan is smaller than 10 mm. 
     
     
         10 . A fan, comprising:
 a motor base having a bearing stand in a center portion thereof;   a bearing accommodated within said bearing stand;   an impeller comprising:
 a metallic case having a top surface and a sidewall extended axially from an outer periphery of said top surface; 
 plural blades disposed around an outer periphery of said metallic case; and 
 a rotating shaft protruded from a center portion of said top surface and penetrated through said bearing stand, wherein no raised ring structure is formed in said top surface of said metallic case, and said rotating shaft and said metallic case are jointed together by a laser welding process; 
   a stator disposed around an outer periphery of said bearing stand; and   a magnetic element disposed on an inner wall of said metallic case and aligned with said stator.   
     
     
         11 . The fan according to  claim 10  wherein said blades are made of metallic material. 
     
     
         12 . The fan according to  claim 11  wherein said blades are integrally formed with said metallic case. 
     
     
         13 . A method for manufacturing a fan, said method comprising steps of:
 providing a metallic case having a top surface and a sidewall extended downwardly from an outer periphery of said top surface;   combining a rotating shaft with said metallic case by a laser welding process, so that said rotating shaft is protruded from a center portion of said top surface of said metallic case;   placing a combination of said rotating shaft and said metallic case within a mold, and producing a hub and plural blades by a plastic injection molding process, wherein said hub is sheathed around said metallic case, and said blades are disposed around an outer periphery of said hub;   providing a motor base having a bearing stand in a center portion thereof, and accommodating a bearing within said bearing stand, and disposing a stator around an outer periphery of said bearing stand; and   disposing a magnetic element on an inner wall of said metallic case, and penetrating said rotating shaft through said bearing such that said magnetic element is aligned with said stator.   
     
     
         14 . The method according to  claim 13  wherein said laser welding process is performed to joint the rotating shaft and said metallic case by arranging welding points in a ring-shaped profile. 
     
     
         15 . The method according to  claim 13  wherein said laser welding process is performed to joint the rotating shaft and said metallic case by arranging welding points symmetrically.