Frameless electric motor assembly

An assembly for an electric motor comprising:

• a stator stack including a plurality of radially extending stator poles extending between first and second ends of said stator stack and defining a central rotor passage through the assembly;
• a plurality of windings extending through stator slots defined between said stator poles;
• a first end cap located adjacent to said first end of said stator stack;
• a second end cap including:
• first and second axially extending end cap legs, said first axially extending end cap leg having a first end located adjacent to said second end of said stator stack and a second end located distal from said stator stack;
• an end portion extending radially inwardly from said second end of said first axially extending end cap leg;
• said second axially extending end cap leg including a first end extending axially from said end portion in a direction away from said second end of said stator stack and a second end located distal from said end portion, said second axially extending end cap leg including an inner surface defining a cylindrical axially extending second end cap bore defining a second end cap bore diameter and being concentrically aligned with said central rotor passage in an axial direction;
• an overmold material extending through said stator stack and extending within and substantially filling an annular space surrounded by said first axially extending end cap leg within said second end cap;
• a cylindrical overmold rotor passage defined through said overmold material extending from a junction between said overmold rotor passage and said cylindrical second end cap bore to said second end of said stator stack, a diameter of said overmold rotor passage from said junction to said second end of said stator stack being substantially equal to said second end cap bore diameter at said junction;
• and
• an endbell formed separately from said second end cap, said endbell including:
• first and second axially extending legs, each of said first and second legs of said endbell including a first end proximate to said second end of said stator stack and a second end distal from said second end of said stator stack;
• said first and second legs of said endbell being radially spaced from each other to define an annular gap therebetween;
• a radially extending first flange portion connecting said first ends of said first and second legs;
• and
• said first leg including an outer surface engaged with said inner surface of said second axially extending end cap leg.

An electric motor assembly comprising:

• a stator assembly comprising:
• a stator stack including a plurality of radially extending stator poles extending between first and second ends of said stator stack and defining a central rotor passage through the electric motor assembly;
• and
• a plurality of windings extending through stator slots defined between said stator poles;
• a rotor assembly comprising:
• a rotor shaft having opposing first and second ends;
• and
• a central portion supported on said rotor shaft and extending through said central rotor passage;
• a first end cap formed of an overmold material located adjacent to said first end of said stator stack;
• a generally cylindrical bearing insert molded into said overmold material forming said first end cap, said bearing insert defining an inner diameter for receiving and supporting a first end bearing within said first end cap for receiving said first end of said rotor shaft;
• a shoulder portion formed in said overmold material of said first end cap and extending radially inwardly from said inner diameter of said bearing insert, said shoulder portion comprising a reference surface for engaging said first end bearing, and said reference surface defining an axial position of said first end bearing;
• a second end cap located adjacent to said second end of said stator stack and defining a second end cap bore concentrically aligned with said central rotor passage in an axial direction;
• and
• an endbell formed separately from said second end cap and at least a portion of said endbell positioned within said second end cap bore, said endbell supporting a bearing for receiving said second end of said rotor shaft.

An electric motor assembly comprising:

• a stator assembly comprising:
• a stator stack including a plurality of radially extending stator poles extending between first and second ends of said stator stack and defining a central rotor passage through the electric motor assembly;
• and
• a plurality of windings extending through stator slots defined between said stator poles;
• a rotor assembly comprising:
• a rotor shaft having opposing first and second ends;
• and
• a central portion supported on said rotor shaft and extending through said central rotor passage;
• a first end cap formed of an overmold material located adjacent to said first end of said stator stack and supporting a first end bearing for receiving said first end of said rotor shaft;
• a second end cap located adjacent to said second end of said stator stack and defining a second end cap bore concentrically aligned with said central rotor passage in an axial direction;
• an endbell formed separately from said second end cap and at least a portion of said endbell positioned within said second end cap bore, said endbell supporting a bearing for receiving said second end of said rotor shaft;
• and
• wherein a radially inner surface of said poles comprise grooves extending longitudinally between said first and second ends of said stator stack, and said first end cap including a shutoff ring engaged against said first end of said stator stack, said shutoff ring being located over ends of said grooves to prevent said overmold material from flowing into said grooves.