Method of manufacturing rotor assembly structure

A method of manufacturing a rotor assembly for an electric motor, said rotor assembly having a central longitudinal axis of rotation about which said assembly is rotated when installed in said motor;

• said assembly including a rotor core having a stack of annular laminations of suitable ferro-magnetic materials with the inner peripheral wall formed by said stack of annular laminations defining a central opening therethrough about said central longitudinal axis, a rotor shaft extending along said central longitudinal axis, a rotor hub between said core and shaft and an oil return tube extending coaxially with said central longitudinal axis comprising the steps of:
• forming said rotor core by molding a pair of annular end rings along opposed faces of said stack of annular laminations;
• inserting a rotor shaft through the central opening defined by said stack of annular laminations and supporting the shaft in concentrically spaced relation from said inner peripheral wall of said stack of annular laminations so that the longitudinal axis of said shaft extends along said central axis of rotation;
• molding a rotor hub between said inner peripheral wall of said stack of annular laminations and said concentrically supported rotor shaft to fix said rotor core to said rotor shaft, said rotor hub being so molded to include a cup-like opening at one end thereof and including the simultaneous molding of a concentric, axially extending mouth portion integral with said rotor hub, said mouth portion extending axially beyond said rotor core and said rotor hub and forming said oil return tube for said rotor assembly.