Commutation device, especially a commutator, and method for producing such a device

DETAILED DESCRIPTION Objects of the present invention are to provide a commutator exhibiting high accuracy with respect to its geometric dimensions and high long-term stability, while being simple to manufacture.
The segments may be fastened on the outer cover by fastening means mounted more or less between the outer cover and the segments.
The outer cover is generally made from an electrically insulating material, particularly of a plastic such as a duroplastic, a thermoplastic, or of a ceramic material.
Consideration may be given, as an alternative, to a metal outer cover such as one of aluminum whose surface is provided with a preferably electrically insulating coating such as a coating of varnish or a layer of metal oxide produced by oxidation of the metal outer cover.
The outer cover may also be built up in two or more layers, and especially, may have a flexible internal hub surrounded by a temperature-stable outer shell on which the segments may be fastened.
The flexible internal hub provides the necessary force fitting for mounting the commutator on an engine shaft.
The commutator segments generally comprise copper or a copper compound.
Consideration may be given also to other materials in keeping with the requirements set for conductivity, temperature stability, and chemical resistance.
The fastening means is preferably applied in layers between the segments and the outer cover, and may be applied prior to fastening on the outer cover and/or the segments.
The outer cover and the segments have interacting means for positioning and orienting the segments relative to the outer cover.
They may be made in the form of punctiform, linear, or planiform projections and matching recesses on the outer cover or on the segments.
The segments, for example, may have studlike projections which may be inserted into matching grooves oriented parallel to the axis of rotation on the circumference of the outer cover.
In the case of a planar commutator, radially oriented studs on a frontal surface may fit into corresponding recesses or grooves on the pertinent segment; or the cylindrical outer cover may have on the edge on its front side an axially projecting and preferably circumferentially annular continuous projection to ensure centering of the disk segment to, be fastened on the front surface