Commutation system for dynamoelectric machines

Claim 2

In a direct current dynamoelectric machine including a rotor assembly rotatable in electrodynamic relationship with a stator assembly, a commutation system comprising: first and second commutator rings formed by two circumferential series of conductive segments spaced apart by thin strips of insulation material and carried by said rotor assembly; first and second sets of brushes contacting spaced segments of said first and second commutator rings; an armature winding including conductive elements disposed around said rotor assembly to define coil sides of coils terminating at first and second coil ends connected together to form at least two closed armature circuit paths; means connecting said first coil ends of one of said closed armature circuit paths to alternate segments of said first commutator ring and means connecting said first coil ends of a second of said closed armature circuit paths to segments between said alternate segments; means connecting said second coil ends of the one closed armature circuit path to alternate segments of said second commutator ring and means connecting said second coil ends of the second closed armature circuit path to segments between said alternate segments; whereby a plurality of working circuits are formed in said armature winding between a first group of pairs of brushes so that a first group of brush contacts are formed in series with said working circuits for conducting work cuRrents therein and a plurality of short circuited paths including preselected coil sides undergoing commutation are formed between a second group of pairs of brushes so that a second group of brush contacts are formed in series with said short circuit paths for conducting local currents developed therein, and further whereby the contact resistance formed by said second group of brush contacts is greater than the contact resistance formed by said first group of brush contacts thereby reducing the distorting effects of said local currents on said work currents flowing in said preselected coils undergoing commutation.

Claim 3

In a direct current dynamoelectric machine including a rotor assembly rotatable in electrodynamic relationship with a stator assembly, a commutation system comprising: first and second commutator rings formed by two circumferential series of conductive segments spaced apart by thin strips of insulation material and carried by said rotor assembly; first and second sets of opposite polarity brushes contacting spaced segments of said first and second commutator rings; an armature winding including conductive elements disposed around said rotor assembly to define coil sides of coils terminating at first and second coil ends connected together to form at least two closed armature circuit paths; means connecting said first coil ends of one of said closed armature circuit paths to alternate segments of said first commutator ring and means connecting said first coil ends of a second of said closed armature circuit paths to segments between said alternate segments; means connecting said second coil ends of said one closed armature circuit path to alternate segments of said second commutator ring and means connecting said second coil ends of said second closed armature circuit path to segments between said alternate segments; a plurality of working circuits formed in each of said closed armature circuit paths with one of said plurality of working circuits extending between one pair of opposite polarity brushes so that a path for work current through said one working circuit includes one pair of brush contacts formed by said one pair of opposite polarity brushes and with rotation of said rotor assembly a short circuit path including preselected coil sides undergoing commutation in each of said closed armature circuit paths is formed between a pair of brushes of common polarity so that a path for local current developed therein includes two pairs of brush contacts formed by said pair of brushes of common polarity, whereby said contact resistance of said two pairs of brush contacts is substantially twice the contact resistance of said one pair of brush contacts to reduce the level of said local currents with reducing the level of said work current flowing through said working circuits.

Claim 4

In a direct current dynamoelectric machine including a rotor assembly rotatable in electrodynamic relationship with a stator assembly, a commutation system comprising: first and second commutator rings formed by two circumferential series of conductive segments spaced apart by thin strips of insulation material and carried by said rotor assembly; first and second sets of opposite polarity brushes contacting spaced segments of said first and second commutator rings; an armature winding including conductive elements disposed around said rotor assembly to define coil sides of coils terminating at first and second coil ends connected together to form at least two closed armature circuit paths; means connecting said first coil ends of one of said closed armature circuit paths to alternate segments of said first commutator ring and means connecting said first coil ends of a second of said closed armature circuit paths to segments between said alternate segments; means connecting said second coil ends of said one closed armature circuit path to alternate segments of said second commutator ring and means connecting said second coil ends of said second closed armature circuit path to segments between said alternate segments; a plurality of working circuits formed in each of said closed armature circuit paths with one of said plurality of working circuits extending between one pair of opposite polarity brushes so that a path for work current through said one working circuit includes one pair of brush contacts formed by said one pair of opposite polarity brushes and with rotation of said rotor assembly a short circuit path including preselected coil sides undergoing commutation in each of said closed armature circuit paths is formed between a pair of brushes of common polarity so that a path for local current developed therein includes two pairs of brush contacts formed by said pair of brushes of common polarity, whereby said contact resistance of said two pairs of brush contacts is substantially twice the contact resistance of said one pair of brush contacts to reduce the level of said local currents with reducing the level of said work current flowing through said working circuits.

Claim 5

In a direct current dynamoelectric machine including a rotor assembly rotatable in electrodynamic relationship with a stator assembly, a commutation system comprising: first and second commutator rings formed by two circumferential series of conductive segments spaced apart by thin strips of insulation material and carried by said rotor assembly; first and second sets of brushes contacting spaced segments of said first and second commutator rings; an armature winding including conductive elements disposed around said rotor assembly defining coil sides of coils connected together to form a first group of coil sides in one closed armature circuit path and a second group of coil sides in another closed armature circuit path; means connecting each coil side of said one group of coil sides between alternate segments of said first commutator ring and alternate segments of said second commutator ring; means connecting each coil side of said second group of coil sides between the remaining unconnected segments of said first commutator ring and the remaining unconnected segments of said second commutator ring; said first group of coil sides and said second group of coil sides being divided into a plUrality of working circuits formed between first pairs of brushes so that a path for work current in series with each working circuit includes one pair of brush contacts; and coil sides at the ends of each working circuit being formed in a plurality of short circuit paths for commutation between second pairs of brushes so that a path for local current includes two pairs of brush contacts, whereby said local current passing through a coil side connected in a short circuit path flows through more contact resistances than said work current flows through when passing through a coil side connected in a working circuit, thereby reducing the level of said local current and arcing at the brush contacts without reducing the work currents.

Claim 6

In a direct current dynamoelectric machine including a rotor assembly rotatable in electrodynamic relationship with a stator assembly, a commutation system comprising: first and second commutator rings formed by two circumferential series of conductive segments spaced apart by thin strips of insulation material and carried by said rotor assembly; first and second sets of brushes contacting spaced segments of said first and second commutator rings; an armature winding including conductive elements disposed around said rotor assembly defining coil sides of coils connected together to form a first group of coil sides in one closed armature circuit path and a second group of coil sides in another closed armature circuit path; means connecting each coil side of said one group of coil sides between alternate segments of said first commutator ring and alternate segments of said second commutator ring; means connecting each coil side of said second group of coil sides between the remaining unconnected segments of said first commutator ring and the remaining unconnected segments of said second commutator ring; said first group of coil sides and said second group of coil sides being divided into a plUrality of working circuits formed between first pairs of brushes so that a path for work current in series with each working circuit includes one pair of brush contacts; and coil sides at the ends of each working circuit being formed in a plurality of short circuit paths for commutation between second pairs of brushes so that a path for local current includes two pairs of brush contacts, whereby said local current passing through a coil side connected in a short circuit path flows through more contact resistances than said work current flows through when passing through a coil side connected in a working circuit, thereby reducing the level of said local current and arcing at the brush contacts without reducing the work currents.

Claim 7

In a direct current motor including a rotor assembly rotatable in electrodynamic relationship with a stator assembly, a commutation system comprising: first and second commutator rings formed by two circumferential series of conductive segments spaced apart by thin strips of insulation material and carried at opposite ends of said rotor assembly; first and second sets of opposite polarity brushes contacting spaced segments of said first and second commutator rings; an armature winding including conductive elements disposed around said rotor assembly defining coil sides of coils connected together in a duplex lap winding configuration forming first and second closed armature circuit paths; means connecting pairs of said coil sides in series in said first closed armature circuit path end between alternate segments of said first commutator ring and connecting pairs of said coil sides in series in said second closed armature circuit path and between alternate segments of said second commutator ring; means connecting the junctions of each of said pairs of coil sides to the unconnected segments of the other commutator ring so that each coil side is connected across segments of each of said first and second commutator rings; groups of coil sides in said first and second closed armature circuit paths defining a plurality of working circuits extending between pairs of opposite polarity brushes in said first and second sets of brushes so that a path for work current is formed in series with each working circuit including one pair of brush contacts; and pairs of coil sides being formed in a plurality of short circuit paths for commutation between pairs of common polarity brushes so that a path for local current is formed including one pair of said coil sides and two pairs of brush contacts, whereby each local current passing through a coil side connected in a short circuit path flows through twice the brush contact resistances that each work current flows through when passing through a coil side connected in a working circuit, thereby reducing the level of said local current and arcing at the brush contacts without reducing the work currents.

Claim 8

In a direct current motor including a rotor assembly rotatable in electrodynamic relationship with a stator assembly, a commutation system comprising: first and second commutator rings formed by two circumferential series of conductive segments spaced apart by thin strips of insulation material and carried at opposite ends of said rotor assembly; first and second sets of opposite polarity brushes contacting spaced segments of said first and second commutator rings; an armature winding including conductive elements disposed around said rotor assembly defining coil sides of coils connected together in a duplex lap winding configuration forming first and second closed armature circuit paths; means connecting pairs of said coil sides in series in said first closed armature circuit path end between alternate segments of said first commutator ring and connecting pairs of said coil sides in series in said second closed armature circuit path and between alternate segments of said second commutator ring; means connecting the junctions of each of said pairs of coil sides to the unconnected segments of the other commutator ring so that each coil side is connected across segments of each of said first and second commutator rings; groups of coil sides in said first and second closed armature circuit paths defining a plurality of working circuits extending between pairs of opposite polarity brushes in said first and second sets of brushes so that a path for work current is formed in series with each working circuit including one pair of brush contacts; and pairs of coil sides being formed in a plurality of short circuit paths for commutation between pairs of common polarity brushes so that a path for local current is formed including one pair of said coil sides and two pairs of brush contacts, whereby each local current passing through a coil side connected in a short circuit path flows through twice the brush contact resistances that each work current flows through when passing through a coil side connected in a working circuit, thereby reducing the level of said local current and arcing at the brush contacts without reducing the work currents.