Carbon commutator

Abstract

A carbon-segment face commutator assembly for an electric motor includes an annular array of copper conductor sections stamped from a single copper blank. The annular array is overmolded with an electrical-conducting resin-bonded carbon composition that mechanically interlocks the conductor sections and defines a circular commutating surface. During overmolding, radial grooves are formed in a bottom surface of the carbon overmold opposite the commutating surface. An annular hub is then formed by overmolding an insulator material around and under the carbon overmold and the conductor section array. The hub insulator material flows into the radial grooves of the carbon overmold and leaves only the circular-commutating surface exposed. The carbon overmold is formed into an annular array of eight electrically-isolated carbon segments by machining radial slots inward from the commutating surface of the carbon overmold to the underlying radial grooves. The slots are cut slightly into the insulator material occupying the radial grooves to ensure that the carbon overmold is completely cut through and the carbon segments are electrically isolated from each other.

Dependencies are inferred from the claim text.