Patent Application
20140217851
Exemplary embodiments pertain to the art of electric machines and, more particularly, to a method of constructing a commutator for an electric machine and an electric machine having a commutator constructed in accordance with the method.
Many electric machines include a housing that supports a stator or field. An armature is arranged in the housing and rotates relative to the field. Generally, the armature includes a shaft that supports a commutator and a plurality of armature windings. The commutator is electrically connected to a plurality of armature windings. The commutator is connected to terminals on the housing through a set of brushes. The brushes ride on, and are in electrical contact with, an outer surface of the commutator. Typically, a spring biases the brushes onto the commutator to maintain the electrical contact.
A commutator typically includes a set of individual contact bars fixed to the rotating shaft of a machine. In a motor, the electrical current flowing through the armature windings via the commutator and brushes interact with a stationary magnetic field produced in the field coil. The interaction of the current and stationary field produces a magnetic force that, in turn, produces a torque on the armature. The torque causes the armature to rotate about an axis defined by the shaft. In a generator, a mechanical torque applied to the shaft creates a motion of the armature windings through the field. Movement of the armature windings in the field induces a voltage that is passed through the commutator to the terminals via the brushes.
Disclosed is a method of constructing a commutator for an electric machine. The method includes forming a commutator assembly including a plurality of commutator bar members linked through a corresponding plurality of bridge elements, rolling the commutator assembly into a commutator form having a substantially continuous, uninterrupted, outer surface, introducing an internal support member that receives an end portion of each of the plurality of commutator bar members into an inner diameter of the commutator form, and separating the plurality of commutator bar members by removing each of the plurality of bridge elements creating a discontinuous outer surface.
Also disclosed is an electric machine including an armature having a commutator constructed by a method including forming a commutator assembly including a plurality of commutator bar members linked through a corresponding plurality of bridge elements, rolling the commutator assembly into a commutator form having a substantially continuous, uninterrupted, outer surface, introducing an internal support member that receives an end portion of each of the plurality of commutator bar members into an inner diameter of the commutator form, and separating the plurality of commutator bar members by removing each of the plurality of bridge elements creating a discontinuous outer surface.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
An electric machine in accordance with an exemplary embodiment is indicated generally at 2 in
Armature winding assembly 42 may include one or more windings or poles that are rotated relative to field 20. Armature assembly 24 also includes a commutator 45 that is electrically connected to armature winding assembly 42 and a terminal block 46. More specifically, commutator 45 is electrically connected to terminal block 46 through first and second brushes 48 and 49 via corresponding first and second conductors 56 and 57. At this point it should be understood that while armature assembly 24 is described as being fixedly mounted to shaft 30, shaft 30 may be fixedly mounted to housing 4 and armature assembly 24 may be rotatably mounted thereupon. Further, it should be understood that the number of brushes electrically connected to commutator 45 may vary.
In accordance with an exemplary embodiment, commutator 45 is formed from a one-piece commutator assembly 80 illustrated in
In accordance with an exemplary embodiment, one-piece commutator assembly 80 is formed into a commutator form 110 having a generally circular cross-section 111 and a substantially continuous outer surface 113 as shown in
Internal support member 120 may be injection molded into commutator form 110 about intermediate portions 97, second end portions 95 and a section of first end portions 94 of commutator bar members 90. Internal support member 120 provides support to commutator bar members 90. Internal support member 120 also physically locates each commutator bar member 90 relative to others of commutator bar members 90. Internal support member 120 extends from a first end section 123, that is positioned at first axial end 115, to a second end section 124. Second end section 124 is spaced from second axial end 116. First end section 123 may be provided with a circumferential flange 127. Internal support member 120 provides electrical isolation between the plurality of commutator bar members 90 upon the removal of bridge elements 92, as will be discussed more fully below. Internal support member 120 also provides electrical isolation between the plurality of commutator bar members 90 and shaft 30 once commutator 45 is mounted to armature assembly 24.
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As shown in
At this point it should be understood that the exemplary embodiments describe a method of constructing a commutator from a one-piece commutator assembly. More specifically, in place of the more labor intensive process of loading individual commutator bars into a fixture, joining the commutator bars and shaping the commutator bars, the exemplary embodiment employs a one-piece commutator assembly that simplifies the construction and manufacture of a commutator. It should also be understood that the one-piece commutator assembly can be formed using a variety of techniques including stamping, extrusion and the like. Also, while described as being wrapped with fiberglass tape, other materials may also be employed to wrap the commutator form.
While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.
