Alternator and method of manufacture

Abstract

An alternator has a molded plastic, electrically conductive D.E. frame in which a sealed bearing is molded in place with the formation of the D.E. frame 14 . When the D.E. frame is removed from its plastics injection mold and while the frame is still hot, the stator is installed in the D.E. frame and the frame allowed to cool and constrict about the stator. The companion S.R.E. frame is preferably fabricated of non-conductive plastics material.

1 . A method of securing a sealed roller bearing having an inner race, an outer race and lubricated rolling elements disposed between the inner and outer races in a molded plastic housing member, comprising: 
 inserting the sealed bearing in a mold configured to form the housing member;    introducing hot, flowable plastics material into the mold and allowing the material to flow about the outer race of the sealed bearing to fix the sealed bearing in the resultant housing member; and    during molding, maintaining the temperature of the sealed roller bearing at a temperature below which the sealed bearing would be damaged by heat.    
   
   
       2 . The method of  claim 1  in which the outer race has an outer surface and opposite end faces, and wherein the plastics material flows about the outer surface and end faces during molding to circumferentially and axially encapsulate the outer race.  
   
   
       3 . A housing assembly comprising: 
 a sealed bearing having an inner race, an outer race, and lubricated roller elements disposed between the inner and outer races;    a molded plastics housing body having a bearing well within which said sealed roller bearing is molded in place including an inner wall surface engaging an outer surface of said outer race, and axial restraining portions extending radially inwardly from said inner wall in overlying relation to axially opposite end faces of said outer race for restraining said bearing axially against removal from said bearing wall.    
   
   
       4 . A housing assembly, comprising: 
 a first housing member fabricated of injection molded plastics material;    a second housing member joinable to said first housing member;    said first housing member having an end wall portion and an outer peripheral side wall portion extending from said end wall portion to provide a generally cup-shaped configuration to said first housing member;    a shaft opening formed in said end wall portion in radially inwardly spaced relation to said outer peripheral side wall portion;    a bearing well wall portion extending from said end wall portion to an upper end in surrounding relation to said shaft opening, said bearing wall portion having an inner wall surface spaced from and concentric with said shaft opening;    an annular end flange section of said end wall portion extending between said shaft opening and said inner wall surface of said bearing well wall portion and providing, together with said bearing well portion, a cup-shaped bearing well;    a bearing disposed in said bearing well, said bearing having an outer race engaging said inner wall surface of said bearing well wall portion and said annular end flange section of said end wall portion; and    an annular retaining flange portion molded as one piece with said bearing well wall portion of said first housing member and extending radially inwardly of said inner wall surface of said bearing well wall portion in overlying, confronting relation to said outer race of said bearing to retain said bearing against removal from said bearing well.    
   
   
       5 . The housing assembly of  claim 4  wherein said outer race of said bearing has a generally cylindrical outer surface and includes a plurality of recesses extending into said outer surface, said bearing well wall portion including interlocking retaining projections extending into said recesses in radially inwardly projecting relation to said inner wall surface of said bearing well wall portion.  
   
   
       6 . The housing assembly of  claim 5  wherein said recesses of said outer race comprise a series of grooves disposed transverse to a longitudinal axis of said shaft opening.  
   
   
       7 . The housing assembly of  claim 5  wherein said recesses comprises a plurality of crisscrossing grooves disposed transverse to a longitudinal axis of said shaft opening and transverse to a plane normal to said longitudinal axis.  
   
   
       8 . The housing assembly of  claim 7  wherein said crisscrossing grooves intersect one another.  
   
   
       9 . The housing assembly of  claim 7  wherein said interlocking retaining projections fill said grooves.  
   
   
       10 . The housing assembly of  claim 4  wherein said bearing includes an inner race supported for free rotation relative to said outer race.  
   
   
       11 . The housing of  claim 4  wherein said bearing comprises a sealed bearing.  
   
   
       12 . The housing assembly of  claim 11  wherein said sealed bearing includes an inner race spaced from said outer race, a plurality of bearing elements disposed in a space between said inner and outer races, and a seal extending between said inner and outer race and sealing said space from the external environment.  
   
   
       13 . A method of making a housing assembly, comprising: 
 fabricating a first housing member;    fabricating a second housing member by injecting hot plastics material into a mold cavity and molding the plastics material around an outer race of a sealed bearing to secure the outer race to the second housing member while retaining relative rotational movement of an inner race of the bearing.    
   
   
       14 . The method of  claim 13 , including forming recesses in an outer surface of the outer race and flowing the plastics material into the recesses during molding.  
   
   
       15 . The method of  claim 14  wherein the recesses are formed by forming a series of crisscrossing grooves in the outer surface and filling such grooves with the plastics material during molding.  
   
   
       16 . The method of  claim 13  including molding the plastics material around opposite ends of the outer race.  
   
   
       17 . The method of  claim 15  including spacing the plastics material from the inner race.  
   
   
       18 . A housing of an electrical device, comprising: 
 a housing body molded of plastics material; and    a ground path of conductive material different than that of said plastics material molded in place and embedded in said plastics material.    
   
   
       19 . A method of fabricating a plastics housing, comprising: 
 molding a housing member in a mold to include a wall surface;    removing the molded housing member from the mold and, while the housing member is still hot from the heat of molding, installing a separate piece in the housing member adjacent the wall surface and permitting the housing member to cool and to cause the wall surface to constrict about the separate piece to secure the separate piece to the housing member.