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Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R39/00—Rotary current collectors, distributors or interrupters
  • H01R39/02—Details for dynamo electric machines
  • H01R39/04—Commutators

Definitions

• the object, therefore, of this invention is to produce means whereby the current-collectors or commutator-brushes may be retained at the points of maximum electro-motive force or work of the generator or motor without undue or destructive sparking, the capacity of the machines being thereby largely increased.
• the current collectors are made of some metal or alloy having inferior conductivity, and making inferior contact compared with copper, and preferably having a hi 'h melting-point.
• Nickel, iron, steel, cobalt, platinum, or palladium might be used, or alloys, such as phosphor-bronze or brass; but I prefer to use German silver for the purpose, for the reason that it otters very great resistance and does not lose its stiffness by heat, as most alloys do.
• the current-collectors, when made as brushes, are made up of layers of wires, which are preferably separated by metal plates, the whole being soldered together into a solid mass at one end.
• the layers of wire are preferably insulated from each other. This may be done by japanning the separating metal plates.
• the wires themselves may also be japanncd and the separating-plates omitted or not, as desired.
• the separating japanned metal plates may be replaced by strips of mica or other suitable insulating material; but thejapanned metal is preferred.
• the brush has its end bearing on the com mutator-cylinder, the ends of all or nearly all the wires being in contactthcrewith.
• the current.in passingfrom one bar to another through the brush is forced to travel up part of the wires to the solid end of the brush and then down other wires to the other bar, the resist ance of the length of the wires being interposed in the local circuit.
• the highrcsistance is due not only to the resistance offered by the metal of the current-collectors, but largely to the inferior electrical contact of the collectors on the commutator-eylinder,whichoccurs when metals or alloys having a conductivity inferior to copper are used for the collectors.
• the contact resistance may be further increased by constructing the commutator-bars or surfacing them with such a metal or alloy as has been described, making an inferior electrical contact compared with copper.
• the sparking due to the taking off of the main current This latter sparking is of course increased by the inferior contact made by the cmrent-collectors.
• the sparking due to the main current can be prevented by increasing the number of collectors or the component parts of the collectors to such an extent. that the spark due to the main current will be reduced to the minimum by division.
• Figure 1 illustrates a dynamo-electric machine or electrddynamie motor with cominutator-brushcs arranged in accordance with my invention
• Fig. 2 a view ofthe commutator, showing several brusher Fig. 3, a view on a larger scale of two bars of a commutator and the improved brush
• Fig. 1, a cross section of the brush
• Fig. 5 an illustration of the course taken by the local current through the electrically-divided brush
• Fig. (3 an illustration showing the course of the local and main currents.
• P N, Fig. 1 are the polar extensions of the field-magnet of the generator or motor, A being the armature; 13, the commutator-cylinder, and 0 t3 the commutator-brushes.
• the varying neutral line on the commutator-cylinder is represented by the dotted line a; and the line of maximum electro-motive force by the dotted line g y.
• the armaturecoils are connected with the commutator-bars at intermediate points, as indicated by the lines in Fig. l, bringing the points of maximum electro-motive force on the commutator opposite the center of the polar extensions of the fieldmagnet.
• the lines .r and g g correspond with the neutral line and the line of maximum electro-motive force on the commutator, and are perpendicular to corresponding lines on the armature.
• Each brush may be constructed of layers of wires (1, of German silver or other inferior conducting metal or alloy, the layers being divided by metal plates or strips 11.
• the wires (0 and plates 1) are formed into a solid mass by soldering at the outer end, 0, of the brush.
• the plates 7) arejapanned, as are also the wires (1, so as to insure agood electrical division of the brush.
• the brush rests with the ends of all its wires bearing on the commutator-cylinder, as shown.
• the course of the local current is indicated by the small arrows in Figs. 5 and 6, while the course of the main current is indicated by the large arrows in Fig. 6.
• the local coil (7, Fig. 6, has its circuit closed at the commutator by the bridge formed by the brush This bridge, however, is of high resistance compared with the coil (1. It is made so by the inferior electrical contact of the brush on the commutator by the inferior conductivity of the metal of which the brush is made, and also by the electrical division of the brush at its inner or hearing end.
• the local current in addition to being forced to overcome the resistance offered by the length of the wires, has to overcome the main current in one side of the bridge formed by the brush.
• the bars 0 of the commutator B may also be made of or surfaced with German silver or other suitable alley or metal, making inferior electrical contact compared with copper. This increases the resistance of the contact and makes the bridges formed by the brushes of higher resistance.
• a current-collector for electrical generators or motors made of inferior conducting material and divided electrically, substantially as set forth.
• I5 A current-collector made of German silver, substantially as set forth.
• a commutator having its bars made of or surfaced with German silver, substantially as set forth.
• Acommutator-brush constrnctedot'wires 20 arranged in layers, the several layers being insulated from each other at the bearing end of the brush, substantially as set forth.
• a commutator brush constructed of wires, the separate wires being all insulated 25 from each other at the bearing end of the brush, substantially as set forth.

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• Motor Or Generator Current Collectors (AREA)

Description

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Family

ID=2345457

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Cited By (8)

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  • US US276233D patent/US276233A/en not_active Expired - Lifetime

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