Abstract:
A method, apparatus, article of manufacture and system for producing a field pole member for electrodynamic machinery are disclosed to, among other things, reduce magnetic flux path lengths and to eliminate back-iron for increasing torque and/or efficiency per unit size (or unit weight) and for reducing manufacturing costs. For example, a field pole member structure can either reduce the length of magnetic flux paths or substantially straighten those paths through the field pole members, or both. In one embodiment, a method provides for the construction of field pole members for electrodynamic machines.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a Continuation-in-Part of U.S. Nonprovisional application Ser. No. 11/255,404, filed on Oct. 20, 2005, which claims priority to U.S. Provisional Application No. 60/622,258, filed on Oct. 25, 2004, all of which are herein incorporated by reference. This application also claims the benefit of U.S. Provisional Application No. 60/773,500, entitled “Field Pole Member for Electrodynamic Machines,” filed on Feb. 14, 2006, the disclosure of which is incorporated by reference. Further, this application incorporates by reference the following: U.S. Pat. No. 7,061,152 B2, entitled “Rotor-Stator Structure for Electrodynamic Machines” and issued on Jun. 13, 2006. 
     
    
     BRIEF DESCRIPTION OF THE INVENTION  
       [0002]     Embodiments of the invention relate generally to electric motors, alternators, generators and the like, and more particularly, to field pole member structures as well as methods of manufacture for forming such field pole member structures.  
       BACKGROUND OF THE INVENTION  
       [0003]     In traditional stator and rotor structures for fractional and sub-fractional horsepower motors, permanent magnets are often integrated into a rotor assembly that typically rotates in the same plane as a ferromagnetic stator structure that provides magnetic return paths for magnet and current-generated flux. Current-generated flux, which is also referred to as Ampere Turn (“AT”)-generated flux, is generated by passing a current through a coil winding that is wrapped about a pole region of a stator member structure. While functional, conventional stator and rotor structures of these and other electric motors have several drawbacks, as are discussed next.  
         [0004]      FIG. 1A  illustrates a traditional electric motor exemplifying commonly-used stator and rotor structures. Electric motor  100  is a cylindrical motor composed of a stator structure  104 , a magnetic hub  106  and a shaft  102 . The rotor structure of motor  100  includes one or more permanent magnets  110 , all of which are attached via magnetic hub  106  to shaft  102  for rotation within stator structure  104 . Stator structure  104  typically includes field poles  118 , each having a coil winding  112  (only one is shown) that is wound about each field pole  118 . Stator structure  104  includes slots  108  used in part to provide a wire passage for winding coil wire about stator field poles  118  during manufacturing. Slots  108  also provide magnetic separation between adjacent field poles  118 . Stator structure  104  includes a peripheral flux-carrying segment  119  as part of magnetic return path  116 . In many cases, stator structure  104  is composed of laminations  114 , which typically are formed from isotropic (e.g., non-grain oriented), magnetically permeable material. Magnetic return path  116 , which is one of a number of magnetic return paths in which permanent magnet-generated flux and AT-generated flux is present, is shown as being somewhat arcuate in nature at peripheral flux-carrying segment  119  but includes relatively sharp turns into the field pole regions  118 .  
         [0005]     One drawback of traditional electric motors, including electric motor  100 , is that magnetic return path  116  requires a relatively long length for completing a magnetic circuit for flux emanating from one rotor magnet pole  110  and traversing via magnetic return path  116  to another rotor magnet pole  110 . Furthermore, magnetic return path  116  is not a straight line, which is preferred for carrying magnetic flux. As shown, magnetic return path  116  has two ninety-degree turns in the stator path. Magnetic return path  116  turns once from field pole region  118  to peripheral flux-carrying segment  119 , and then again from peripheral flux-carrying segment  119  to another field pole region  118 . Both of these turns are suboptimal for carrying flux efficiently. As implemented, magnetic return path  116  requires more material, or “back-iron,” than otherwise is necessary for carrying such flux between field poles. Consequently, magnetic return paths  116  add weight and size to traditional electric motors, thereby increasing the motor form factor as well as cost of materials to manufacture such motors.  
         [0006]     Another drawback of conventional electric motors is that laminations  114  do not effectively use anisotropic materials to optimize the flux density and reduce hysteresis losses in flux-carrying poles, such as through field poles  118 , and stator regions at peripheral flux-carrying segment  119 . In particular, peripheral flux-carrying segment  119  includes a non-straight flux path, which limits the use of such anisotropic materials to reduce the hysteresis losses (or “iron losses”). Hysteresis is the tendency of a magnetic material to retain its magnetization. “Hysteresis loss” is the energy required to magnetize and demagnetize the magnetic material constituting the stator regions, wherein hysteresis losses increase as the amount of magnetic material increases. As magnetic return path  116  has one or more turns of ninety-degrees or greater, the use of anisotropic materials, such as grain-oriented materials, cannot effectively reduce hysteresis losses because the magnetic return path  116  in peripheral flux-carrying segment  119  would cut across the directional orientation of laminations  114 . For example, if direction  120  represents the orientation of grains for laminations  114 , then at least two portions of magnetic return path  116  traverse across direction  120  of the grain, thereby retarding the flux density capacity of those portions of stator peripheral flux-carrying segment  119 . Consequently, anisotropic materials generally have not been implemented in structures similar to stator structure  104  since the flux paths are usually curvilinear rather than straight, which limits the benefits provided by using such materials.  
         [0007]     Yet another drawback of conventional electric motors is the relatively long lengths of magnetic return path  116 . Changing magnetic fields, such as those developed at motor commutation frequencies, can cause eddy currents to develop in laminations  114  in an orientation opposing the magnetic field inducing it. Eddy currents result in power losses that are roughly proportional to a power function of the rate at which the magnetic flux changes and roughly proportional to the volume of affected lamination material.  
         [0008]     Other drawbacks of commonly-used electric motors include the implementation of specialized techniques for reducing “cogging,” or detent torque, that are not well-suited for application with various types of electric motor designs. Cogging is a non-uniform angular torque resulting in “jerking” motions rather than a smooth rotational motion. This effect usually is most apparent at low speeds and applies additive and subtractive torque to the load when field poles  118  are at different angular positions relative to magnet poles. Further, the inherent rotational accelerations and decelerations cause audible vibrations.  
         [0009]      FIG. 1B  illustrates an axial motor as another type of traditional electric motor exemplifying commonly-used stator and rotor structures. Conventional axial motor geometries have been used to overcome the disadvantages of other common motor technologies, including radial motors. But when axial motors are designed in accordance with conventional design tenets relating to radial geometries, inherent limitations can arise that restrict the number of applications for which axial motors can be used. As such, the use of axial motors has been somewhat limited to relatively specialized niches.  
         [0010]     Further, axial motors are usually constructed with an array of longitudinal field poles having perpendicular field pole faces at each end. The perpendicular field pole faces are usually positioned to face single or dual rotating planar assemblies of magnets, as shown in  FIG. 1B . Axial motor  121  is shown to include arrays of longitudinal field poles as stator assembly  126 , which is in between two rotating planar assemblies of magnets  131 , which are mounted on a front magnet disk  124  and a back magnet disk  128 . Also shown, are a front cover plate  122  and a rear cover plate  130  that contain bearings to hold the motor shaft in position. The field poles of stator assembly  126  typically are made of assemblies of steel laminations with perpendicular field pole faces to maintain a constant air gap with the rotating magnets  131 .  
         [0011]     A traditional axial motor typically has a fixed number or area of pole faces that can confront an air gap area, and, thus, can produce torque that is limited to the relative strength of the magnet. This means that to make a high torque motor, high strength (and therefore high cost) magnets are generally required. This, among other things, reduces the attractiveness of the axial motor design.  
         [0012]     In view of the foregoing, it would be desirable to provide a field pole member as a structure that reduces the above-mentioned drawbacks in electric motors and generators, and to, for example, increase output torque and efficiency either on a per unit size or per unit weight basis, or both, as well as to conserve resources during manufacturing and/or operation.  
       SUMMARY OF THE INVENTION  
       [0013]     A method, apparatus, article of manufacture and system for producing a field pole member for electrodynamic machinery are disclosed to, among other things, reduce magnetic flux path lengths, and to eliminate back-iron for increasing torque and/or efficiency per unit size (or unit weight) as well as for reducing manufacturing costs. In one embodiment, a field pole member structure can be formed to, for example, either reduce the length of magnetic flux paths or substantially straighten those paths through the field pole members, or both. In another embodiment, a method provides for the construction of field pole members for electrodynamic machines. The method includes positioning a plurality of magnetic flux conductors for affixation, for example, together longitudinally to form at least a field pole core of a field pole member. The method also can include forming a pole face at an end of the field pole member. That is, the method can include forming one or more pole faces at the one or more ends of the field pole member. In one embodiment, the field pole core is a substantially straight field pole core to provide either a straight flux path or a substantially straight flux path between the pole face and another pole face or the other end of the field pole member. In some embodiments, the methods of manufacture provide for field pole member structure that, among other things, can enhance motor efficiencies, as well as conserve resources to reduce manufacturing costs by, for example, minimizing wastage. The various embodiments relating to field pole member manufacturing can configure the field pole members, for example, to accommodate single and multiple magnet rotors, whereby the magnets can have any type of shape. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0014]     The invention is more fully appreciated in connection with the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0015]      FIG. 1A  illustrates a commonly-used radial stator structure implemented in a traditional electric motor;  
         [0016]      FIG. 1B  illustrates an axial motor as another type of traditional electric motor;  
         [0017]      FIG. 2  is a generalized flow for producing a field pole member in accordance with a specific embodiment of the invention;  
         [0018]      FIG. 3  illustrates an example of a field pole member produced by a specific embodiment of the invention;  
         [0019]      FIG. 4  depicts an example of a field pole core produced by a specific embodiment of the invention;  
         [0020]      FIG. 5  depicts an example of another field pole core produced by another specific embodiment of the invention;  
         [0021]      FIG. 6  is a flow diagram illustrating an example of a manufacturing flow for producing a field pole member, according to an embodiment of the invention;  
         [0022]      FIG. 7  is a flow diagram illustrating another example of a manufacturing flow for producing a field pole member, according to another embodiment of the invention;  
         [0023]      FIG. 8A  illustrates a system for manufacturing a field pole member in accordance with an embodiment of the invention;  
         [0024]      FIG. 8B  illustrates another system for manufacturing a field pole member in accordance with another embodiment of the invention;  
         [0025]      FIG. 9  illustrates an over-molding process to form pole faces in accordance with one embodiment of the invention;  
         [0026]      FIG. 10  illustrates an integrating process to form pole shoe faces in accordance with an embodiment of the invention;  
         [0027]      FIGS. 11A  to  11 C illustrate examples of field pole cores produced by embodiments of the invention;  
         [0028]      FIG. 12  illustrates an over-molding process to form pole faces in accordance with one embodiment of the invention;  
         [0029]      FIG. 13  illustrates a field pole member manufactured in accordance with an embodiment of the invention;  
         [0030]      FIG. 14  illustrates a field pole member manufactured in accordance with yet another embodiment of the invention;  
         [0031]      FIG. 15  illustrates a field pole member manufactured in accordance with still yet another embodiment of the invention; and  
         [0032]      FIG. 16  illustrates a field pole member manufactured in accordance with at least one embodiment of the invention.  
     
    
       [0033]     Like reference numerals refer to corresponding parts throughout the several views of the drawings. Note that most of the reference numerals include one or two left-most digits that generally identify the figure that first introduces that reference number.  
       DETAILED DESCRIPTION  
     Definitions  
       [0034]     The following definitions apply to some of the elements described with respect to some embodiments of the invention. These definitions may likewise be expanded upon herein.  
         [0035]     As used herein, the term “air gap” refers to a space, or a gap, between a magnet surface and a confronting pole face. Such a space can be physically described as a volume bounded at least by the areas of the magnet surface and the pole face. An air gap functions to enable relative motion between a rotor and a stator, and to define a flux interaction region. Although an air gap is typically filled with air, it need not be so limiting.  
         [0036]     As used herein, the term “back-iron” commonly describes a physical structure (as well as the materials giving rise to that physical structure) that is often used to complete an otherwise open magnetic circuit. In particular, back-iron structures are generally used only to transfer magnetic flux from one magnetic circuit element to another, such as either from one magnetically permeable field pole member to another, or from a magnet pole of a first magnet to a magnet pole of a second magnet, or both, without an intervening ampere-turn generating element, such as coil, between the field pole members or the magnet poles. Furthermore, back-iron structures are not generally formed to accept an associated ampere-turn generating element, such as one or more coils.  
         [0037]     As used herein, the term “coil” refers to an assemblage of successive convolutions of a conductor arranged to inductively couple to a magnetically permeable material to produce magnetic flux. In some embodiments, the term “coil” can be described as a “winding” or a “coil winding.” The term “coil” also includes foil coils (i.e., planar-shaped conductors that are relatively flat).  
         [0038]     As used herein, the term “coil region” refers generally to a portion of a field pole member around which a coil is wound.  
         [0039]     As used herein, the term “core” refers to a portion of a field pole member where a coil is normally disposed between pole shoes and is generally composed of a magnetically permeable material for providing a part of a magnetic flux path. In some embodiments, the formation of the “core” also forms the field pole member with or without pole faces. In other embodiments, the core is formed as a base structure onto which end caps or the like can be formed.  
         [0040]     As used herein, the term “field pole member” refers generally to an element composed of a magnetically permeable material and being configured to provide a structure around which a coil can be wound (i.e., the element is configured to receive a coil for purposes of generating magnetic flux). In some embodiments, a field pole member includes a core (i.e., core region) and at least two pole shoes, each of which is generally located near a respective end of the core. But in other embodiments, a field pole member includes a core and only one pole shoe. In some embodiments, the term “field pole member” can be described generally as a “stator-core.” In at least one embodiment, a field pole member generally has an elongated shape such that the length of the field pole member (e.g., the distance between the ends of the field pole member) is generally greater than its width (e.g., the width of the core).  
         [0041]     As used herein, the term “active field pole member” refers to an assemblage of a core, one or more coils, and at least one pole shoe. In particular, an active field pole member can be described as a field pole member assembled with one or more coils for selectably generating ampere-turn flux. In some embodiments, the term “active field pole member” can be described generally as a “stator-core member.” 
         [0042]     As used herein, the term “ferromagnetic material” refers to a material that generally exhibits hysteresis phenomena and whose permeability is dependent on the magnetizing force. Also, the term “ferromagnetic material” can also refer to a magnetically permeable material whose relative permeability is greater than unity and depends upon the magnetizing force.  
         [0043]     As used herein, the term “field interaction region” refers to a region where the magnetic flux developed from two or more sources interact vectorially in a manner that can produce mechanical force and/or torque relative to those sources. Generally, the term “flux interaction region” can be used interchangeably with the term “field interaction region.” Examples of such sources include field pole members, active field pole members, and/or magnets, or portions thereof. Although a field interaction region is often referred to in rotating machinery parlance as an “air gap,” a field interaction region is a broader term that describes a region in which magnetic flux from two or more sources interact vectorially to produce mechanical force and/or torque relative to those sources, and therefore is not limited to the definition of an air gap (i.e., not confined to a volume defined by the areas of the magnet surface and the pole face and planes extending from the peripheries between the two areas). For example, a field interaction region (or at least a portion thereof) can be located internal to a magnet.  
         [0044]     As used herein, the term “generator” generally refers to an electrodynamic machine that is configured to convert mechanical energy into electrical energy regardless of, for example, its output voltage waveform. As an “alternator” can be defined similarly, the term generator includes alternators in its definition.  
         [0045]     As used herein, the term “magnet” refers to a body that produces a magnetic field externally unto itself. As such, the term magnet includes permanent magnets, electromagnets, and the like.  
         [0046]     As used herein, the term “motor” generally refers to an electrodynamic machine that is configured to convert electrical energy into mechanical energy.  
         [0047]     As used herein, the term “magnetically permeable” is a descriptive term that generally refers to those materials having a magnetically definable relationship between flux density (“B”) and applied magnetic field (“H”). Further, “magnetically permeable” is intended to be a broad term that includes, without limitation, ferromagnetic materials, including laminate steels and cold-rolled grain oriented (“CRGO”) steels, powder metals, soft magnetic composites (“SMCs”), and the like.  
         [0048]     As used herein, the term “pole face” refers to a surface of a pole shoe that faces at least a portion of the flux interaction region (as well as the air gap), thereby forming one boundary of the flux interaction region (as well as the air gap). In some embodiments, the term “pole face” can be described generally as either a “stator surface” or a “flux interaction surface” (or a portion thereof), or both.  
         [0049]     As used herein, the term “pole shoe” refers to that portion of a field pole member that facilitates positioning a pole face so that it confronts a rotor (or a portion thereof), thereby serving to shape the air gap and control its reluctance. A pole shoe of a field pole member is generally located near an end of the core starting at or near a coil region and terminating at the pole face. In some embodiments, the term “pole shoe” can be described generally as a “stator region.” 
         [0050]     As used herein, the term “soft magnetic composites” (“SMCs”) refers to those materials that are comprised, in part, of insulated magnetic particles, such as insulation-coated magnetically permeable powder metal materials that can be molded to form an element of the rotor-stator structure of the present invention.  
         [0051]     As used herein, the term “transition region” refers to an optional portion of a pole shoe that facilitates offsetting or diverting a segment of a flux path (e.g., within a core region) to another segment of the flux path (e.g., within a pole shoe). One or more pole shoes can implement transition regions to improve motor volumetric utilization (e.g., by placing coils in a compact configuration nearer to an axis of rotation). Generally, the transition region can keep the reluctance of the field pole member relatively low while facilitating compaction of the elements constituting an electrodynamic machine. Such elements include shafts, field pole members, magnets and the like.  
       Discussion  
       [0052]      FIG. 2  is a generalized flow for producing a field pole member in accordance with a specific embodiment of the present invention. Flow  200  provides for a manufacturing technique to produce field pole member structures that can carry amounts of magnetic flux in, for example, unidirectional direction or a substantially unidirectional direction. These structures can provide for increased performance and economical manufacturing of electrodynamic machines, such as electric motors and generators, as well as electric solenoids and other applications. In one embodiment, flow  200  positions magnetic flux conductors in relatively close proximity for affixation together to form a field pole core of a field pole member at  201 . Flow  200  also can be used to form the field pole member itself, according to some embodiments. As used herein, the term “magnetic flux conductor” in some embodiments describes an elongated structure composed of magnetically permeable material. Optionally, a magnetic flux conductor can have grain orientation along a longitudinal direction (i.e., lengthwise). Examples of magnetic flux conductors include wires and laminations composed of magnetically permeable material, such as silicon steel. At  203 , pole faces can be formed with respect to the field pole cores to provide flux interaction surfaces. These pole faces can be configured to confront, for example, conical-shaped or cylindrical-shaped magnets as described in U.S. Pat. No. 7,061,152 B2 and U.S. patent application Ser. No. 11/255,404, respectively. In one embodiment the pole faces can be sculpted to form sculpted pole faces to confront conical-shaped, cylindrical-shaped magnets, or the like. In various other embodiments, the pole faces can be configured to confront other magnets having any other kind of shapes, such as trapezoidal magnets in the case of linear and/or rotary motors. A field pole member is produced at  205 . In various embodiments, flow  200  can affix magnetic flux conductors together at  201  prior to or subsequent to forming pole faces at  203 . In one embodiment, flow  200  can affix magnetic flux conductors together at  201  at the same time or at substantially the same time as forming pole faces at  203 .  
         [0053]      FIG. 3  illustrates an example of a field pole member produced by a specific embodiment of the present invention. Field pole member  300  includes a field pole core  302  and pole shoe members  304 . Each pole shoe member  304  includes an example of a pole face, which is pole face  306 . In one embodiment, field pole core  302  is over-molded to form pole shoe members  304 . In some cases, over-molding also encapsulates the magnetic flux conductors constituting field pole core  302 . In other cases, over-molding only forms pole shoe members  304 . As used herein, the term “cap” in some embodiments refers to pole shoe members  304 . In at least one embodiment, field pole core  302  is a straight or a substantially straight field pole core and provides a substantially straight flux path between pole faces  306 . In other embodiments, field pole core  302  can include or can be coupled to transition regions. In a specific embodiment, pole shoe members  304  are formed as “caps” composed of magnetically permeable material. As such, pole shoe members  304  can be formed by pressing magnetic powders into a specific shape that defines the contours of pole faces  306 . The individual magnetic powder particles that are used to form pole shoe member  304  can, at least in some cases, have an insulation coating, which improves the loss characteristics of field pole member  300 . One example of implementing caps as pole shoe members  304  is shown in  FIG. 10 . In as least one embodiment, field pole member  300  has substantially the same desirable magnetic properties and low loss characteristics found in field pole members produced with laminations alone (i.e., with pole faces being formed in the laminations). Pressed end-caps and over-molding allow designers additional freedom to create field pole member and stator end-geometries using laminations, wires, or any other type of magnetic flux conductor.  
         [0054]      FIG. 4  depicts an example of a field pole core produced by a specific embodiment of the invention. As shown in this example, field pole core  400  includes a number of laminations  401 . In one embodiment, field pole core  400  has a square-shaped cross-section  402  if each of laminations  401  has the same width, “W.” In at least one embodiment, one or more laminations  401  have varying widths, W. For example, by varying widths of lamination  401 , a teardrop-shaped cross-section  404  can be formed for field pole core  400 . In at least one embodiment, laminations  401  are can be isolated (e.g., electrically, magnetically, etc.) from each other by, for example, being coated with an electrically-insulating material, such as an oxide, glass coating or the like. One example of an electrically-insulating material is black oxide. In a specific embodiment, laminations  401  can be affixed to each other with a bonding agent. In various embodiments of the invention, the orientation of the lamination widths, W, can be either radial (or substantially radial) or concentric (substantially concentric), or in any other orientation, relative to an axis of rotation. According to one embodiment, the shape of the field pole core and/or the manufacturing process cost, in whole or in part, can determine the orientation in which to stack laminations  401 .  
         [0055]     Cross-section  450  of an envelope  404  is shown in  FIG. 4 , which shows laminations  401  having varying widths, W. The varying widths can produce field pole core  400  having teardrop-shaped cross-section  450  for envelop  404 . In one embodiment, one or both ends of field pole core  400  can include a pole face  410  formed to provide a uniform air gap or a substantially uniform air gap. Or, in some embodiments, pole face  410  is formed to mate with a cap (not shown) having, for example, a sculpted mating surface. In various embodiments, pole face  410  is formed by, for example, sculpting one or more ends of field pole core  400  (to form a field pole member), or sculpting a cap for a pole shoe. As used herein, the term “sculpted pole face” can generally refer, at least in one embodiment, to a “contoured” pole face or an “angled” pole face. Note that in at least one embodiment, pole face  410  can be formed as a contoured pole face, which includes a contoured surface. The contoured surface can be substantially coextensive with a curved surface, whereby the degree of curvature can be fixed or variable over the surface of pole face  410 . As such, pole face  410  can be referred to as a contoured pole face  410 , according to at least one embodiment. In some cases, the curved surface can include a portion that is coextensive with an arc that lies on a surface of, for example, a cone or a cylinder. Further, the contoured surface can be a concave surface in one embodiment. In another embodiment, one or both ends of field pole core  400  can include a flat or a substantially flat, but angled pole face  420 . This angled pole face can be formed by cutting field pole member  400  at its ends so that each of the pole faces is contoured either to confront a permanent magnet or to readily mate with a cap, or both. In some embodiments, the terms “cut” and “cutting,” as applied to field pole members, refer to the separation of magnetic flux conductors from a main body of starting material, such as from rolls of slitted laminations or from rolls of wires. Thus, cutting field pole members can form “sculpted” pole faces in some embodiments. Generally, such “cuts” are lateral in nature (i.e., generally occurring along a width of a magnetic flux conductor) rather than longitudinal. As used herein, the term “angled,” in at least one embodiment, refers to a characteristic of a surface (or a portion thereof) that faces at least a portion of the flux interaction region (as well as the air gap). The surface can be a flux interaction surface of a pole shoe (e.g., a pole face) or a surface of a magnet. According to various embodiments, angled pole face  420  can be adapted to confront, for example, an angled surface of a trapezoidal magnet implemented in, for example, a linear or a rotary motor.  
         [0056]      FIG. 5  depicts an example of another field pole core produced by another specific embodiment of the invention. Field pole core  500  includes a number of wires as magnetic flux conductors. As cross-sectional view (“A-A”)  550  depicts, field pole core  500  includes a number of wires  501  and interstitial material  502 . In the example shown, wires  501  have circular cross-sections. Wires  501  can provide relatively high magnetic flux carrying capabilities for field pole core  500  similar to field pole cores constructed of magnetic steel laminations. As such, wires  501  allow a variety of field pole core shapes that generally might otherwise be difficult and/or expensive to create with other techniques, such as with laminations, according to some embodiments. For example,  FIG. 5  shows that wires  501  can be aggregated to form a triangular cross-section shape  510  for field pole core  500 . Wires  501  can also be used to form other shapes, such as oval or tear-drop cross-section shapes, for field pole core  500 . As used herein, the term “envelope” can refer generally, at least in some embodiments, to one or more surfaces that, as boundaries, encompass magnetic flux conductors. An envelope can have a cross-section shaped as either a square, a circle, a tear drop, an oval, or any other shape that can be produced by a mold, a die, a compaction wheel, or the like. In at least one instance, the cross-section for an envelop lies in a plane substantially perpendicular to a line parallel to the length of a magnetic flux conductor. In at least one embodiment, wires  501  can be isolated from each other by implementing, for example, a coating that includes an electrically-insulating material, such as oxide or the like.  
         [0057]     Wires  501  can lower losses generally associated with, for example, laminations because wires  501  can provide reduced cross sections and cross-sectional area therein, thereby reducing the eddy currents therein. In various embodiments, wires  501  can have square-shaped cross sections  504 , diamond-shaped cross sections  506 , and hexagonal-shaped cross-sections  508 , among other types of shapes for cross-sections of wires  501 . Cross-sections  504  and  506  can, for example, reduce the volume of interstitial material  502 . In a specific embodiment, interstitial material  502  can include a bonding agent and/or magnetic particles. The bonding agent can affix wires  501  to each other, whereas the magnetic particles can enhance the flux-carrying capabilities of field pole core  500  by filling what otherwise may be voids among wires  501  with flux-carrying material. Examples of magnetic particles include powders composed of soft magnetic composites (“SMCs”) as “magnetic powder.” Note that use of composite material, such as SMC, can, at least in one embodiment, be used to manufacture complex field pole member structures that can have negligible or no material waste of wire  501 , as well as relatively very little amount of magnetic powder in interstitial material  502 . In some cases, magnetic particles can have an insulating exterior shell around each powder particle, such iron oxide. In one embodiment, interstitial material  502  excludes magnetic particles and only includes binding agent. In other embodiments, interstitial material  502  can include either magnetic particles or binding agents, or both.  
         [0058]      FIG. 6  is a flow diagram illustrating an example of a manufacturing flow for producing a field pole member, according to an embodiment of the invention. At  602 , a number of magnetic flux conductors are cut to a length that generally approximates the length of the finally manufactured field pole core. In some embodiments, each magnetic flux conductors are cut at an identical length (e.g., when implementing caps), wherein in other embodiments, each of the magnetic flux conductor can be cut to a length that approximates the distance between pole faces. In at least one embodiment, the lengths of the magnetic flux conductors can vary to accommodate the varying distance between the pole faces. At  604 , the number of magnetic flux conductors can be deposited into a mold, which can be described as a location or as an approximate location at which affixation of magnetic flux conductors occurs. At least one example of a mold can form additional structural and/or functional features for a field pole member, such as sculptured pole faces and/or locating features. Optionally, a binding (or bonding) agent can be introduced into the mold at  606  if such an agent has yet to be applied either to the magnetic flux conductors or to the starting material (e.g., a steel coil) from which the magnetic flux conductors are formed. A binding agent can be used to hold the field pole member assembly together. Optionally, the binding agent can be a powdered material mixed with the magnetic powder at  608 , and heated and/or pressurized at  610  to cure the bonding agent. Alternatively the binding agent can be a penetrating adhesive having a relatively low viscosity, which is applied at  606  once the mold has been packed with wires at  604  and magnetic powder at  608 . Note that when the magnetic flux conductors are laminations, then adding magnetic powder at  608  can be omitted as there can be negligible or no voids in the interfaces between laminations.  
         [0059]     In some embodiments, the introduction of a binding agent occurring at  606  can be performed prior to the separation (e.g., cutting) of magnetic flux conductors from that material from which they originate. For example, if magnetic flux conductors are laminations, then the binding agent can be applied to a roll (or coil) of starting material (e.g., a pre-cut roll). In this case, the binding agent can be applied as a coating prior to slitting (e.g., shear slitting) or any other form of longitudinally-oriented cutting. In at least one embodiment, flow  600  applies the binding agent between  602  and  604 . That is, a binding agent, such as a thin film adhesive, can be applied onto elongated strips after slitting process has formed the strips from the starting material.  
         [0060]     Flow  600  continues from  610  to form pole shoe members  304  ( FIG. 3 ) or “caps.” In one embodiment, flow  600  moves to  612  to form pole shoe members as caps by using an over-molding technique. Here, an over-molding operation can use an adhesive (e.g., glue) combined with insulated magnetic powder material to form a desired shape for the pole faces at  616 . By over-molding at least the ends of the field pole core, the pole faces can be shaped in a controlled manner for producing flux interaction surfaces that can have characteristics for forming an air gap with a magnet, such as a conical or cylindrical magnet. In another embodiment, flow  600  moves from  610  to  614 . Here, pole shoe members  304  ( FIG. 3 ) or “caps” can be integrated with a field pole core (“F.P. core”) to form a field pole member having pole faces. At  614 , the integration of the pole shoe members to, for example, the ends of a field pole core can include applying a binding adhesive with or without a soft magnetic composite powder to the ends of the field pole core, and pressing the pole shoe members to the ends of the field pole to form a specific shape for a pole face at  616 . As such, the pole face formed at  616  can be a sculpted pole face. Thus, a motor manufacturer can reduce an inventory of field pole members for electrodynamic machines requiring either conical or cylindrical magnets, for example. Interchangeable caps adapted for the conical and cylindrical magnets can be integrated with a common field pole core as needed, thereby preventing build up unnecessary inventory. When integrating (e.g., by fastening) the pole shoe members to the field pole core, a combination of a binding adhesive and a magnetic powder filler can be used. While the magnetic flux carrying capability of the pole shoe members and the magnetically-filled binding adhesive may differ from those field pole cores composed of laminations, the relatively short flux travel distance across the binding adhesive minimally might affect the flux-carrying capability of the field pole member. At  620 , flow  600  concludes (“done”) by producing a field pole member. In some embodiments, flow  600  can form transitions regions with respect to the field pole members.  
         [0061]      FIG. 7  is a flow diagram illustrating another example of a manufacturing flow for producing a field pole member, according to another embodiment of the invention. At  702 , a number of magnetic flux conductors are pulled to an affixation site at which the magnetic flux conductors can be affixed to each other. For instance, an affixation site can include a die. In other instances, the affixation site can include shaping members, such as a set of mating wheels (e.g., shaped mating wheels). An example of such wheels are described in  FIG. 8B  as compaction wheels. The die and/or mating wheels maintain a cross-sectional shape for the field pole core. As such, mating wheels can form a number of cross-sectional shapes, such as a round, oval and tear drop shapes. So at  702 , the magnetic flux conductors are each of pulled from a supply of elongated magnetic flux conductors, such as from a number of spools. Generally, magnetic flux conductors are pulled as elongated magnetic flux conductors having lengths that are greater than the length of the field pole core. As used herein, the term “elongated magnetic flux conductors” refers in some embodiments to magnetic flux conductors that have yet to be cut to form a field pole member of the embodiments of the invention.  
         [0062]     At  704 , a binding agent is applied to the magnetic flux conductors. For example, the binding agent can be aerosolized and deposited on (i.e., sprayed on) each of the magnetic flux conductors as they are pulled from the supply of elongated magnetic flux conductors to a die (i.e., the affixation site). Applying the binding agent in an aerosol form is well-suited for application with laminations. As another example, the binding agent can be rolled onto the magnetic flux conductors. In alternative embodiments, the introduction of a binding agent at  704  can be implemented prior to pulling magnetic flux conductors to the affixation site at  702 . For example, a binding agent can be applied to either a steel coil prior to slitting of laminates, or to a wire before it is rolled onto a spool.  
         [0063]     If the magnetic flux conductors are laminations, then flow  700  moves to  708 . But if the magnetic flux conductors are wires, then flow  700  moves to  706 . Magnetic powder is applied to the wires at  706  to fill the voids. In one embodiment, both the binding agent and the magnetic powder can be applied at the same time by transferring (e.g., by brushing) the combination of binding agent-magnetic powder onto the wires. At  708 , a die is either heated or activated to apply pressure, or both, to cure the binding agent to form bar stock (e.g., metal bars). Alternatively, a heater can perform the curing process separate from the die. In some embodiments, a mating wheel at  708  heats and/or applies pressure to cure the binding agent to form the bar stock. At  710 , the affixed magnetic flux conductors are cut to form field pole cores. That is, each of the plurality of magnetic flux conductors is cut at a length approximate to the length of the field pole core after affixing the plurality of magnetic flux conductors together to form affixed magnetic flux conductors. Then, flow  700  proceeds from  710  to  720 , wherein  712 ,  714 ,  716  and  720  are similar in functionality as respective  612 ,  614 ,  616  and  620  of  FIG. 6 . Flow  700  can provide a cost-effective, constant cross-section process that continually forms field pole members. In one embodiment, flow  700  is similar to a pultrusion process. In some embodiments, flow  700  forms transitions regions with respect to the field pole members.  
         [0064]      FIG. 8A  illustrates a system for manufacturing a field pole member in accordance with an embodiment of the invention. System  800  includes a supply (“spooled laminations”)  802 , elongated magnetic flux conductors  803  (each of which is wound onto a spool  801 ), an optional spray-on binder  804 , a combined die-heater  806 , a pulling mechanism  807 , and one or more cutters  808  for separating the affixed magnetic flux conductors from elongated magnetic flux conductors  803 . Supply  802  includes a number of laminations arranged on spools. In one embodiment, each of elongated magnetic flux conductors  803  on respective spools has the same width. In an alternative embodiment, elongated magnetic flux conductors  803  can be of varying widths to, for example, produce tear drop-shaped field pole member cores. In some cases, sheet steel supplied by a steel mill is first slit to the various widths and re-spooled into supply  802  of  FIG. 8A . Spools  801  are then loaded into the production machine. During processing, optional spray-on binder  804  sprays at least a heat-activated binding agent onto the individual elongated magnetic flux conductors  803  as they are pulled through a die  806 . A heater stage of die  806  activates the binding agent, which solidifies the stack into bar stock. Pulling mechanism  807  pulls the affixed magnetic flux conductors into one or more cutters  808 . For instance, two cutters  808  can be used in succession to create the final field pole cores. System  800  can reduce waste of material during the original slitting operation and possibly during the final cuts as compared to, for example, stamping laminations out of sheets of steel. Cutter  808  can form straight cuts (e.g., perpendicular to elongated magnetic flux conductors  803 ) or angled cuts. Water jet cutting is one example of cutter  808  suitable to practice some embodiments of the invention.  
         [0065]     In some embodiments, wire having a grain orientation for enhancing magnetic properties can be used. The initial tooling costs for system  800  can be relatively low, and can be amortized over small volumes. The use of a binding agent to bind the magnetic flux conductors together can generally assist in reducing the noise and vibration of the final composite structure of a field pole member as compared to an equivalent structure made of, for example, unbonded steel laminations. In various embodiments, the laminations can also be affixed by laser welding, e-beam welding and the like.  
         [0066]     In some embodiments, magnetic flux conductors  803  can be formed as laminations using a stamping process. FIGS.  14  to  16  illustrate examples of laminations formed by, for example, stamping to produce field pole cores and/or field pole members. However, in reference to  FIG. 8A , a slitting process can be used to longitudinally separate a starting material (or coil) into different widths for elongated magnetic flux conductors  803 . Generally, laminations formed from a slitting process and a separation process, such as by cutting at cutters  808 , are likely to have more favorable magnetic characteristics than those produced by stamping. Slitting processes suitable to practice some embodiments include standard shear wheel slitting, water jet slitting, and laser cutting. In some cases, the stamping process might disturb the magnetic properties of elongated magnetic flux conductors  803 . In at least one embodiment, magnetic flux conductors  803  can be wires.  
         [0067]      FIG. 8B  illustrates another system for manufacturing a field pole member in accordance with another embodiment of the invention. System  850  can generally be used to form field pole cores as well as the field pole members themselves. As shown, system  850  is used to form field pole members and field pole cores formed by, for example, incorporating composite over elongated magnetic flux conductors, such as wires. Generally, wires  858  are fed via wire guide  859  from supply spools  856  into a hopper  860 . Also, powered metal and/or SMC feed stock (“powder”)  854  can be fed into hopper  860 . In at least one embodiment, the size, the wire cross-section, and number of wires  858  can be selected as a function of, for example, process convenience and strength, rather than their magnetic properties. In various embodiments, the volume of wires  858  can vary in relation to the total volume of extrusion  899  or field pole cores  890  to achieve different properties. In one instance, the manufacturing process can be aligned vertically to allow gravity to aid the combination of materials in hopper  860  and to generally aid alignment of the extruded material while it moves through the system. System  850  can be aligned horizontally as well as in other variations of alignment.  
         [0068]     Shaker  862  functions to vibrate the powder to combine it with magnetic wires  858  at incorporation site  864  within hopper  860 . Shaker  862  is configured to shake hopper  860  to distribute powder  854  around wires  858 , and to provide some initial densification of the mix as it enters an initial compaction site  864 . In some embodiments, initial compaction wheels  872  are disposed adjacent hopper  860  to pass the combination of the wire and powder to a heating element. Generally, initial compaction wheels  872  can be started in synchronization with wires  858  take-up spool  892  to ensure constant wire tension—at least at start-up. The presence of the tensioned wires can eliminate a problem, at least in some instances, relating to extrusion processes (e.g., a problem of controlling the straightness of the extruded material).  
         [0069]     In one embodiment, induction heater  876  heats extruded material  899  at induction heater coils  874 , which are generally at temperatures of less than or about 500° C. System  850  also can include an additional (or final) compaction stage  875 . In one embodiment, additional compaction stage  875  includes a number of additional compaction wheels  878  for further compacting the extrusion. In one example, hydraulic pistons  877  apply pressures via additional compaction wheels  878  (e.g., four wheels) to extruded material  899 . Note that any number of additional compaction wheels  878  can be used. Further, additional compaction wheels  878  can be powered by motors to synchronize the speed of extrusion  899  passing through with the speed of the wire take up by take-up spool  892 . Additional compaction wheels  878  can be adjacent to each other so that their angled or contoured surfaces  871  meet or almost meet. Angled or contoured surfaces  871  on wheels  872  and/or  878  can be configured to form the outside diameter portions of extrusion  899  to shape a portion of the field pole core/member, such as the cross-sectional area of a field pole core/member. Note that additional compaction wheels  878  can replace or supplement the use of the die  806  of  FIG. 8A  to aid in reducing the friction at the forming process. In some embodiments, temperature and speed sensors  879  and process controller  873  can control the functions of system  850 , including the final compaction stage  875 .  
         [0070]     Powered tension wheels  880  can apply tension to extrusion  899 , for example, once the wires are released at the bottom of the process at take-up spool  892 . Extrusion  899  can be passed to the cutoff station  881  at which at least the field pole cores  890  are separated from extrusion  899 . Cutoff station  881  can be energized to cut the extrusion into a predetermined length by, for example, blades  884 , which can follow extrusion  899  at the same relative speed. Blades  884  can include moving saw blades. Once cutoff station  881  is energized, the wires that were fed to the take up spool  892  to provide initial tension are no longer needed.  
         [0071]      FIG. 9  illustrates an over-molding process to form pole faces in accordance with one embodiment of the invention. Here, mold  902  includes two halves, one of which includes contours  906  for forming pole faces. In operation, a field pole core  904  is composed, for example, of laminations. Field pole core  904  then is deposited into mold  902 . After the over-molding process, a field pole member is produced.  
         [0072]      FIG. 10  illustrates an integrating process to form pole shoe faces in accordance with an embodiment of the invention. In  FIG. 10 , a field pole core  1012  has pole shoe members  1014  integrated or fastened thereto to form a field pole member  1010 . Note that while field pole cores  1012  can be composed of laminations, as shown,  FIG. 10 , field pole core  1012  can be composed of any other magnetic flux conductor, including wires. In various embodiments, pole shoe members  1014  can include sculpted pole faces  1016 , each of which can be either a contoured pole face or an angled pole face.  
         [0073]      FIGS. 11A  to  11 C illustrate examples of field pole cores produced by various embodiments of the invention. As shown in  FIG. 11A , cutting an elongated bar stock of affixed wires can produce field pole core  1100 . The ends of field pole cores are shown to be cut at an angle  1102 . Note too that cutting an elongated bar stock at angle  1102  produces at least two field pole cores  1100  having non-symmetrically shaped ends, as shown in  FIG. 11B . To produce two consecutive field pole cores  1100  having symmetrically shaped ends, as shown in view  1130  of  FIG. 11B , a notch  1138  is cut out to separate field pole cores  1132  and  1134 . Notch  1138  represents wastage, and requires two cuts to separate the field pole cores  1132  and  1134  from each other. In one embodiment, the cross-section of the field pole core is such that it produces symmetrically-shaped ends, as shown in  FIG. 11C . For example, consider view  1140  of  FIG. 11C  in which the field pole core has a circular cross-section. By producing symmetrically-shaped ends, a single cut can separate field pole cores  1142  and  1144 , for example, rather than the two cuts of non-symmetrically shaped field pole cores that results in notch  1138  of  FIG. 11B . As such, a single cut used to form field pole cores, and, thus, can reduce the wastage associated with notch  1138 . Two single cuts—as shown in view  1140 —can produce a field pole core  1144  having symmetrical cross-sections and ends  1149 , both of which generally face direction “A.” Those two single cuts also form symmetrically shaped ends  1160  for the other field pole cores  1142  and  1146 , with those ends  1160  facing direction “B.” Angle  1148  of the cut is generally configured to confront these surfaces of, for example, a conical magnet (not shown) being at a specific angle from an axis of rotation.  
         [0074]      FIG. 12  illustrates an over-molding process to form pole faces in accordance with one embodiment of the invention. Here, mold  1202  includes two halves, one of which includes contours  1206  on surface portions of mold  1202  for forming pole faces. Contours  1206  can be used to form contoured pole faces, such as contoured pole faces  1308  in  FIG. 13 . Referring back to  FIG. 12 , a field pole core  1204  can be composed, for example, of wires and can have cross-section  1250 , which is shown to include wires in cross-section view  1260 . Field pole core  1204  is deposited into mold  1202 . After the over-molding process, a field pole member is produced. The parts out of the mold can have additional machining operations, if necessary, without shorting the wires together (provided the machining was accounted for in the design of the mold).  
         [0075]      FIG. 13  illustrates a field pole member manufactured in accordance with an embodiment of the invention. In  FIG. 13 , mold  1302  produces a field pole member  1304 , which creates two pole shoe members  1306  as well as pole faces  1308 . In yet another embodiment, field pole member  1304  is composed of soft magnetic composite powder and is produced by inserting the powder into mold  1202  of  FIG. 12  and then pressed into shape by mold  1302 .  
         [0076]      FIG. 14  illustrates a field pole member manufactured in accordance with yet another embodiment of the invention. In  FIG. 14 , laminations  1402  are stamped out of sheets of steel and affixed to each other to form field pole member  1400 .  
         [0077]      FIG. 15  illustrates a field pole member manufactured in accordance with still yet another embodiment of the invention. In  FIG. 15 , laminations  1504  are stamped out of sheets of steel and affixed to each other to form field pole member  1500  having sculpted pole faces  1507  having skewed field pole face edges to reduce detent and torque ripple. In particular, field pole member  1500  is constructed from a number of laminations  1504 . Laminations  1504  can be patterned to provide sculpted pole faces  1507 . Sculpted pole face  1507  is bound by both a first skewed edge  1550  and a second skewed edge  1552 , whereas the other pole face  1507  at the other pole shoe is bound by a first skewed edge  1580  and a second skewed edge  1582 .  
         [0078]     In other embodiments, field pole members can implement wires as magnetic flux conductors to form field pole cores and/or members shown in FIGS.  14  to  16 . As such, sculpted pole faces can be formed by, for example, a molding process as shown in  FIG. 12 . In some embodiments, a sculpted pole face can be referred to as a skewed pole face, especially if the pole face includes features as a function of detent and/or torque ripple.  
         [0079]      FIG. 16  illustrates a field pole member manufactured in accordance with another embodiment of the invention. In  FIG. 16 , laminations  1602  are configured to aggregate together in a concentric orientation, or a substantially concentric orientation, in relation to an axis of rotation. In this example, different laminations  1602  can have different sizes, and can optionally include features, such as a pole shoe feature. To form field pole member  1600 , laminations  1062  can be drawn from reels of pre-slit lamination material  1604  and assembled together. With this approach, scrap or waste material can be reduced, at least in some cases. Examples of the above-mentioned features include a stepped-back transition region  1608 , which, for example, can reduce leakage between field pole cores/members once assembled. Stepped-back transition region  1608  can be formed in association with other features, such as part of a pole shoe, according to at least one embodiment. Another feature can form sculpted and/or skewed pole faces, such as shaped field pole face  1610 .  
         [0080]     A practitioner of ordinary skill in the art requires no additional explanation in making and using the embodiments of the rotor-stator structure described herein but may nevertheless find some helpful guidance by examining the following references in order from most to least preferred: “IEEE 100: The Authoritative Dictionary of IEEE Standard Terms,” Institute of Electrical and Electronics Engineers (Kim Breitfelder and Don Messina, eds., 7th ed. 2000), “General Motor Terminology,” as defined by the Small Motor and Motion Association (“SMMA”), and “Standard Specifications for Permanent Magnet Materials: Magnetic Materials Producers Association (“MMPA”) Standard No. 0100-00,” International Magnetics Association.  
         [0081]     Embodiments of the invention can be implemented in numerous ways, including as a system, a process, an apparatus, or a series of program instructions on a computer readable medium such as a computer readable storage medium or a computer network where the program instructions are sent over optical or electronic communication links. In general, the steps of disclosed processes may be performed in an arbitrary order, unless otherwise provided in the claims.  
         [0082]     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the various embodiments of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practice embodiments of the invention. In fact, this description should not be read to limit any feature or aspect of the present invention to any embodiment; rather features and aspects of one embodiment can readily be interchanged with other embodiments.  
         [0083]     Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed; many alternatives, modifications, equivalents, and variations are possible in view of the above teachings. For the purpose of clarity, technical material that is known in the technical fields related to the embodiments has not been described in detail to avoid unnecessarily obscuring the description. Thus, the various embodiments can be modified within the scope and equivalents of the appended claims.  
         [0084]     Further, the embodiments were chosen and described in order to best explain the principles of the invention and its practical applications; they thereby enable others skilled in the art to best utilize the various embodiments with various modifications as are suited to the particular use contemplated. Notably, not every benefit described herein need be realized by each embodiment of the present invention; rather any specific embodiment can provide one or more of the advantages related to the various embodiments of the invention. In the claims, elements and/or operations do not imply any particular order of operation, unless explicitly stated in the claims. It is intended that the following claims and their equivalents define the scope of the invention.