Abstract:
Electrodynamic apparatus such as a motor, generator or alternator is configured having a stator core assembly formed of pressure shaped processed ferromagnetic particles which are pressure molded in the form of stator modules. These generally identical stator modules are paired with or without intermediate modules to provide the stator core structure for receiving field winding components. In one embodiment, two sets of the paired stator modules are combined in tandem to enhance operational functions without substantial diametric increases in the overall apparatus.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
       [0001]     Not applicable.  
       BACKGROUND OF THE INVENTION  
       [0002]     Investigators in the electric motor arts have been called upon to significantly expand motor technology from its somewhat static status of many decades. Improved motor performance particularly has been called for in such technical venues as computer design and secondary motorized systems carried by vehicles, for example, in the automotive and aircraft fields. With progress in these fields, classically designed electric motors, for example, utilizing brush-based commutation, have been found to be unacceptable or, at best, marginal performers.  
         [0003]     From the time of its early formation, the computer industry has employed brushless d.c. motors for its magnetic memory systems. The electric motors initially utilized for these drives were relatively expensive and incorporated a variety of refinements, for instance as necessitated with the introduction of rotating disc memory. Over the recent past, the computer industry has called for very low profile motors capable of performing in conjunction with very small disc systems and at substantially elevated speeds.  
         [0004]     Petersen, in U.S. Pat. No. 4,745,345, entitled “D.C. Motor with Axially Disposed Working Flux Gap”, issued May 17, 1988, describes a PM d.c. motor of a brushless variety employing a rotor-stator pole architecture wherein the working flux gap is disposed “axially” with the transfer of flux being in parallel with the axis of rotation of the motor. This “axial” architecture further employs the use of field windings which are simply structured, being supported from stator pole core members, which, in turn, are mounted upon a magnetically permeable base. The windings positioned over the stator pole core members advantageously may be developed upon simple bobbins insertable over the upstanding pole core members. Such axial type motors have exhibited excellent dynamic performance and efficiency and, ideally, may be designed to assume very small and desirably variable configurations.  
         [0005]     Petersen in U.S. Pat. No. 4,949,000, entitled “D.C. Motor”, issued Aug. 14, 1990 describes a d.c. motor for computer applications with an axial magnetic architecture wherein the axial forces which are induced by the permanent magnet based rotor are substantially eliminated through the employment of axially polarized rotor magnets in a shear form of flux transfer relationship with the steel core components of the stator poles. The dynamic tangentially directed vector force output (torque) of the resultant motor is highly regular or smooth lending such motor designs to numerous high level technological applications such as computer disc drives which require both design flexibility, volumetric efficiency, low audible noise, and a very smooth torque output.  
         [0006]     Petersen et al, in U.S. Pat. No. 4,837,474 entitled “D.C. Motor”, issued Jun. 6, 1989, describes a brushless PM d.c. motor in which the permanent magnets thereof are provided as arcuate segments which rotate about a circular locus of core component defining pole assemblies. The paired permanent magnets are magnetized in a radial polar sense and interact without back iron in radial fashion with three core components of each pole assembly which include a centrally disposed core component extending within a channel between the magnet pairs and to adjacently inwardly and outwardly disposed core components also interacting with the permanent magnet radially disposed surface. With the arrangement, localized rotor balancing is achieved and, additionally, discrete or localized magnetic circuits are developed with respect to the association of each permanent magnet pair with the pole assembly.  
         [0007]     Petersen in U.S. Pat. No. 5,659,217, issued Aug. 19, 1997 and entitled “Permanent Magnet D.C. Motor Having Radially-Disposed Working Flux-Gap” describes a PM d.c. brushless motor which is producible at practical cost levels commensurate with the incorporation of the motors into products intended for the consumer marketplace. These motors exhibit a highly desirable heat dissipation characteristic and provide improved torque output in consequence of a relatively high ratio of the radius from the motor axis to its working gap with respect to the corresponding radius to the motors&#39; outer periphery. The torque performance is achieved with the design even though lower cost or, lower energy product permanent magnets may be employed with the motors. See also: Petersen, U.S. Pat. No. 5,874,796, issued Feb. 23, 1999.  
         [0008]     The above-discussed PM d,c, motors achieve their quite efficient and desirable performance in conjunction with a multiphase-based rotational control. This term “multiphase” is intended to mean at least three phases in conjunction with either a unipolar or bipolar stator coil excitation. Identification of these phases in conjunction with rotor position to derive a necessary controlling sequence of phase transitions traditionally has been carried out with two or more rotor position sensors. By contrast, simple, time domain-based multiphase switching has been considered to be unreliable and impractical since the rotation of the rotor varies in terms of speed under load as well as in consequence of a variety of environ mental conditions.  
         [0009]     Petersen in application for U.S. patent Ser. No. 10/706,412, filed Nov. 12, 2003, entitled “Multiphase Motors With Single Point Sensing Based Commutation” describes a simplified method and system for control of multiphase motors wherein a single sensor is employed with an associated sensible system to establish reliable phase commutation sequencing.  
         [0010]     Over the years of development of what may be referred to as the Petersen motor technology, greatly improved motor design flexibility has been realized. Designers of a broad variety of motor driven products including household implements and appliances, tools, pumps, fans and the like as well as more complex systems such as disc drives now are afforded an expanded configuration flexibility utilizing the new brushless motor systems. No longer are such designers limited to the essentially “off-the-shelf” motor varieties as listed in the catalogues of motor manufacturers. Now, motor designs may become components of and compliment the product itself in an expanded system design approach.  
         [0011]     During the recent past, considerable interest has been manifested by motor designers in the utilization of magnetically “soft” processed ferromagnetic particles in conjunction with pressed powder technology as a substitute for the conventional laminar steel core components of motors. So structured, when utilized as a motor stator core component, the product can exhibit very low eddy current loss which represents a highly desirable feature, particularly as higher motor speeds and resultant core switching speeds are called for. As a further advantage, for example, in the control of cost, the pressed powder assemblies may be net shaped wherein many intermediate manufacturing steps and quality considerations are avoided. Also, tooling costs associated with this pressed powder fabrication are substantially lower as compared with the corresponding tooling required for typical laminated steel fabrication. The desirable net shaping pressing approach provides a resultant magnetic particle structure that is 3-dimensional magnetically (isotropic) and avoids the difficulties encountered in the somewhat two-dimensional magnetic structure world of laminations. See generally U.S. Pat. No. 5,874,796 (supra).  
         [0012]     The high promise of pressed powder components for motors and generators initially was considered compromised by a characteristic of the material wherein it exhibits relatively low permeability. However, Petersen, in U.S. Pat. No. 6,441,530, issued Aug. 27, 2000 entitled “D.C. PM Motor With A Stator Core Assembly Formed Of Pressure Shaped Processed Ferromagnetic Particles”, describes an improved architecture for pressed powder formed stators which accommodates for the above-noted lower permeability characteristics by maximizing field coupling efficiencies.  
         [0013]     As the development of pressed powder stator structures for electrodynamic devices such as motors and generators has progressed, investigators have undertaken the design of larger, higher power systems. This necessarily has lead to a concomitant call for larger press molded structures. The associated molding process calls for press pressures adequate to evolve requite material densities to gain adequate electrical properties. To achieve those densities, press pressures are needed in the 40 tons per square inch to 50 tons per square inch range. As a consequence the powdered metal pressing industry suggest that the design of molded parts exhibit aspect ratios (width or thickness to length in the direction of pressing) equal to or less than about 1:5. Thus as the length of stator core component structures increase, their thickness must increase to an extent that a resultant shape becomes so enlarged in widthwise cross section as to defeat the design goal, with attendant loss of both the economies of cost and enhanced performance associated with this emerging pressed powder technology.  
       BRIEF SUMMARY OF THE INVENTION  
       [0014]     The present invention is addressed to electrodynamic apparatus and a method of manufacturing the stator core assemblies thereof utilizing press powder technologies wherein requisite stator core material densities are achieved while part thicknesses and volumes are retained within desirable dimensional limits. Requisite ratios of component widths or thicknesses to corresponding lengths are maintained in proper combinations while minimizing thicknesses of core structures through the employment of two or more stator core modules or components which, following their press forming, are selectively combined to define a sequence of module core components over which field windings are positioned. Because the stator core modules may be geometrically identical, tooling costs may be conserved through employment, in effect, of a single mold to produce them.  
         [0015]     In one embodiment of the invention, paired stator core modules are combined in tandem along the axis of the electrodynamic apparatus to achieve an enhanced functional capacity while minimizing the diametric extent of the device within which they perform. With this arrangement, two or more sets of phase defining field windings are utilized with wire diameters of smaller extent. These phase defining windings advantageously then may be combined for simultaneous excitation through employment of a series or parallel electrical interconnection.  
         [0016]     Where stator assembly sizes are called for which are large, the stator core modules may be press formed in segmented fashion. The resulting segments then may be combined in mutually abutting fashion to form the stator modules. Further, the configuration of these segments may be selected such that segments otherwise aligned within paired stator modules can be pre-wound with field winding elements prior to being abuttably joined together.  
         [0017]     A convenient feature of the stator assemblies resides in the utilization of electrically insulative shields positioned over the mutually outwardly disposed winding support surfaces of field winding core portions of the stator pole core member. In general, the pole core members are formed with wire receiver troughs within which field windings are retained. To facilitate the circuit association of the windings from pole-to-pole within the stator assembly, the insulative shield may be configured to extend outwardly to define an outwardly open wire receiving channel adjacent the inner surface of an associated back iron region of the stator structure. The stator structures revealed in the embodiments presented herein are all shown in the classical inward facing salient stator pole configuration. This should not be considered a limitation as U.S. Pat. No. 6,441,530 (supra) illustrates both inward and outward facing stators and is incorporated by reference herewith.  
         [0018]     Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.  
         [0019]     The invention, accordingly, comprises the apparatus and method possessing the construction, combination of elements, arrangement of parts and steps which are exemplified in the following detailed description.  
         [0020]     For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a perspective view of electrodynamic apparatus incorporating the features of the invention;  
         [0022]      FIG. 2  is a sectional view taken through the plane  2 - 2  shown in  FIG. 1 ;  
         [0023]      FIG. 3  is a sectional view taken through the plane  3 - 3  shown in  FIG. 2 ;  
         [0024]      FIG. 3A  is a partial top view of an alternate configuration for a core member flux interaction region;  
         [0025]      FIG. 4  is a perspective view of a core component configured in accordance with the invention;  
         [0026]      FIG. 5  is an exploded view showing a combination of four of the components shown in  FIG. 4 ;  
         [0027]      FIG. 6  is an electrical schematic diagram showing the parallel association of two “Y” winding configurations employed with the stator structure of  FIG. 5 ;  
         [0028]      FIG. 7  is a schematic representation of a phase winding configuration;  
         [0029]      FIG. 8  is a partial sectional view of electrodynamic apparatus according to the invention showing interpole winding geometry;  
         [0030]      FIG. 9  is a sectional view of another electrodynamic apparatus structuring according to the invention;  
         [0031]      FIG. 10  is a sectional view of another electrodynamic apparatus stator component structuring according to the invention;  
         [0032]      FIG. 11  is a sectional view of a electrodynamic apparatus structure having a segmented stator core architecture;  
         [0033]      FIG. 12  is a perspective view of a stator core component architecture shown in  FIG. 11 ;  
         [0034]      FIG. 13  is a sectional view of apparatus according to the invention showing a multi-segmented stator core component architecture; and  
         [0035]      FIG. 14  is a perspective view of a stator core component as depicted in connection with  FIG. 13 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]     In the discourse to follow radially salient pole stator structures and the techniques of their formation and assembly are described in conjunction with d.c. PM motors having an architecture for deriving relatively higher power outputs, for example, about 250 watts and above. The structuring and techniques apply additionally to other forms of motors such as doubly salient pole motors and to electricity generators. Thus, the term “electrodynamic apparatus” is utilized with the meaning that it incorporates motors and generators employing the noted techniques of stator formation. In developing such electrodynamic devices utilizing magnetically soft composite pressed powder technology for stator construction the developer will establish a variety of dimensional parameters for electrical reasons establishing, for instance, appropriate material thicknesses to achieve flux transfer and avoidance of saturation. These electrical criteria are generated by calculation. When those requisite thicknesses are so established with judicious safety factors, the utilization of pressed powder material above and beyond those thicknesses will contribute only to weight and cost without improvement in device performance. Once these dimensional parameters are established, then the developer is confronted with the mandates of the powder metal pressing industry requiring molded part aspect ratios calling for structural thicknesses well beyond those necessary for electrical performance criteria.  
         [0037]     Looking to  FIG. 1 , a d.c. PM motor configured according to the precepts of the invention is represented generally at  10 . Motor  10  is formed with a cylindrical outer sleeve  12  formed, for example, of aluminum or plastic to which is connected cylindrical end caps  14  and  16 . These caps  14  and  16  are retained in place by three hex head machine screws  18 - 20 . Extending from an opening  22  within end cap  14  is a rotor shaft  24 .  
         [0038]     Referring to  FIG. 2 , device  10  is revealed in section. Rotor shaft  24  is seen disposed symmetrically about a rotor axis  26 . The shaft  24  is necked down to define an annular shoulder  28  which engages the inner race of a ball bearing  30 , which in turn, is seated within a cylindrical bearing cavity  32  formed within end cap  14 . In similar fashion, the opposite end of shaft  24  is necked down to define an annular shoulder  34  which abuttably engages the inner race of a ball bearing  36 . The outer race of ball bearing  36 , in turn, is biased inwardly by a wavy washer  40  interposed between bearing  36  and bearing cavity surface  42 .  
         [0039]     Shaft  24  supports a rotor represented generally at  44  which is formed having a cylindrical core  46  formed of aluminum extending to an outer cylindrical surface  48 . Coupled with that surface  48  is a cylindrical back iron  50  formed of ferrous material and extending to a cylindrical back iron surface  52 . Surface  52 , in turn, supports a cylindrical radially magnetized permanent magnet  54  which extends to flux confronting surfaces  56 . Those flux confronting surfaces provide, in this embodiment, a sequence of six magnetic regions of alternating polarity generally extending in parallel with the rotor axis  26 .  
         [0040]     Additionally supported for rotation upon shaft  24  is a polymeric annular disc  58  which rotationally supports an annularly-shaped sequence of sensible system permanent magnets shown in cross section at  60 . The annular magnets sequence  60  is shown mounted within an annular steel back iron  62  supported, in turn, upon an annular shoulder  64  formed within disc  58 . Mounted internally upon end cap  16  is a printed circuit board  66  which functions to carry an integrated circuit  68  along with appropriate driver transistors and one or more Hall effect sensors as shown at  70 . Sensor  70  is positioned for magnetic field response to the magnetic regions of sensible system magnet  60 .  
         [0041]     An annular stator assembly is represented generally at  80 . Assembly  80  is formed using a material composed of magnetically soft pressure shaped processed ferromagnetic particles which are generally mutually insulatively associated. These materials such as Somaloy 500, are sometimes referred to as involving soft magnetic composite technology and are marketed, inter alia, by North American Hoganas, Inc. of Hollsopple, Pa. Assembly  80  is configured as a radial salient pole stator having nine, angularly spaced apart identical stator pole core members. Looking additionally to  FIG. 3 , these core members are represented in general at  82   a - 82   i.  Core members  82   a - 82   i  are formed integrally with and extend radially inwardly from a portion of a cylindrically shaped back iron  84  having a widthwise extent identified by paired arrows  86 . Extending radially inwardly from back iron  84  are nine winding core portions  88   a - 88   i  of the stator pole core members. The widthwise dimension or thickness of these winding core portions  88   a - 88   i  are identified at paired arrows  90 . Winding core portions  88   a - 88   i  extend radially inwardly to respective integrally formed flux interaction portions  92   a - 92   i.  The widthwise extent or thickness of these flux interaction portions is represented at paired arrows  94 . Depending on the arc length of the flux interaction portions relative to the widthwise extent of the winding core portions the flux interaction portions on  92   a - i  on either side of the widthwise extent of the winding core portions may be tapered to a lesser widthwise extent at the extremes of its arcuate extent as shown in  FIG. 3A . These flux interaction portions extend to respective arcuate flux interaction surfaces  96   a - 96   i  which are spaced from flux confronting surface  56  of rotor  44  to define a functioning or working gap  98 . Regions as at  92 ″ are more typical when the air gap between adjacent stator pole tips is less than twice the distance from the flux interaction surface to the magnet back iron.  FIG. 3  reveals that the permanent magnet feature of rotor  44  is formed with six magnetic regions extending along the motor axis. These regions are identified at  100   a - 100   f.    
         [0042]     Core members  82   a - 82   i  and back iron  84  are not formed as a unitary part in their axial plane. Were they to be so formed, the widthwise dimensions required to meet the pressing criteria for pressure shaped processed ferromagnetic particles would increase significantly causing the resulting structure to be less desirable for its intended electrodynamic function. In accordance with the precepts of the invention, the back iron and core members are constructed, for the instant embodiment, as four identically structured modules, each of which is formed meeting press forming criteria and optimum electrical criteria. In this regard, the ratio of each of the noted predetermined widthwise or thickness dimensions with respect to their length in the direction of pressing is equal to or less than a ratio of about 1 to 5. Looking to  FIG. 4 , a perspective view of the uppermost one of these modules is represented in general at  110 . In the following descriptions top and bottom surfaces of a stator module or component such as seen in perspective in  FIG. 4  are defined as the axial end surfaces of each component. In an assembly of components these surfaces form outward facing and inward facing surfaces of an electrodynamic device. In general, the term “bottom is used in an inward sense, and the term “top” is used in an outward sense. The terms “component” or “module” as used herein are intended to mean not only identical components but components having different configurations, for instance, with stator core portions made from different molds. Module  110  is formed with a back iron portion  84 ′ which extends from a back iron top surface region  116 ′ a predetermined length l 1  (press direction), to a back iron bottom surface region  118 ′. That length, l 1 , is determined with respect to the wall thickness regions  86 ,  90  and  94  and noted high pressure pressing criteria. In similar fashion, the flux interaction portions, which are now identified generally at  92 ′, for module  110  extend from flux interaction top surface regions certain of which are identified at  120 ′ and extend the same length, l 1 , to a flux interaction bottom surface region is which identified at  122 ′. As revealed in  FIGS. 2 and 4 , back iron top surface region  116 ′ and flux interaction top surface region  120 ′ reside in a common plane which is perpendicular to the axis  26 . In similar fashion, back iron bottom surface region  118 ′ and flux interaction bottom surface region  122 ′ reside in a common plane which is parallel with the top surface region common plane.  FIG. 4  also reveals the presence of top and bottom alignment notches shown respectively at  124 ′ and  126 ′.  
         [0043]     Certain of the winding core portions of module  110  are identified in general in  FIG. 4  at  88 ′. Looking additionally to  FIG. 2 , these winding core portions  88 ′ extend from a winding core top surface region certain of which are identified at  128 ′ a length l 2  to a winding core bottom surface region certain of which are revealed at  130 ′.  FIG. 4  reveals that the winding core top surface regions  128 ′ reside in a common plane and that the edges thereof are chamfered to facilitate the mounting of field winding wire thereover. In contrast, the winding core bottom surface regions  130 ′ need not be chamfered inasmuch as they will be seen not to receive or support field winding wire.  FIGS. 2 and 4  further reveal that the winding core top surface regions  128 ′ are recessed inwardly from the back iron top surface regions  116 ′ and flux interaction top surface regions  120 ′ to define receiver troughs certain of which are identified at  132 ′. Receiver troughs  132 ′ further are defined by a radially inwardly slopping surface  134 ′ formed within the module back iron portion  84 ′. In similar fashion, a radially outward slopping surface, certain of which are identified at  136 ′ is formed in each of the stator pole core member flux interaction portions.  
         [0044]     Looking additionally to  FIG. 5 , it may be observed that stator assembly  80  is configured with four modules which are shown as being identified for illustrative purposes and thus are configured as described in conjunction with  FIG. 4 . Accordingly, not only do the modules have dimensional aspect ratios which permit their compression molding and practical shapes, but also they are economically fabricable inasmuch as for the present embodiment a singular molding tool is employed. The four modules are revealed in  FIGS. 2 and 5  at  110 - 113 . To facilitate the identification of the identical portions of these modules, such elements are numerically identified in the same fashion as provided in  FIG. 4  but with priming provided for modules  110  through  113  respectively extending from a single prime to four primes. Modules  111  and  112  may be referred to as medial modules with medial stator pole core members of medial dimensions. Note in  FIG. 5  that modules  110  and  111  are paired such that, for example, the back iron top surface regions  116 ′ and  116 ″ as well as the corresponding flux interaction top surface regions  120 ′ and  120 ″ face mutually outwardly. The same mutual orientation is provided in conjunction with components  112  and  113 . Mutual angular alignment or slight misalignment of all of the modules  110 - 113  is provided by three alignment pins  138 - 140 . In this regard, alignment pin  138  engages notches  126 ′ and  126 ″. Aligning pin  139  engages notches  124 ″ and  124 ″′, and alignment pin  140  engages notches  126 ″′ and  126 ″″.  
         [0045]     Returning to  FIG. 2 , modules  110 - 113  are retained in mutual abutment and alignment by combination of cylindrical sleeve  12 , end caps  14  and  16  and their mutual coupling by machine screws  18 - 20 . For the device design at hand, a mutual contacting abutment between paired modules as at  110  and  111  or  112  and  113  is not a requisite arrangement. In this regard, the paired components will perform appropriately if slightly separated in an axial sense with shock absorbing materials or the like.  
         [0046]      FIG. 2  illustrates, inter alia, stator pole core member  82   g  in section as well as a non-sectional view of core member  82   c.  These core members, as described above, are configured with modules  110 - 113  in paired and stacked relationship. Note in  FIG. 2  that the winding core portions of these core members support two as opposed to a single field winding. In this regard, core member  82   g  is seen supporting field windings  150   g  and  152   g.  Field winding  150   g  is wound about the receiver troughs  132 ′ and  132 ″ of respective modules  110  and  111 , while field winding  152   g  is wound about receiver troughs  132 ″′ and  132 ″″ of respective modules  112  and  113 . Similarly, field winding  150   c  is seen wound about receiver troughs  132 ′ and  132 ″ at core member  82   c  and additionally the field winding  152   c  is shown wound about receiver troughs  132 ″′ and  132 ″″ of that core member. Conventional brushless motor architecture will incorporate a single winding for each core member as at  82   a - 82   i.  Where the core members are formed, for example, utilizing conventional thin laminations, larger gage field winding wire is necessitated because of the single winding per stator pole member and the accumulated winding bundle will protrude above and below the core members. By virtue of the utilization of net shaped modules  110 - 113 , receiver troughs as at  132 ′- 132 ″″ can be employed which fully incorporate the field winding wire bundles, i.e., the outermost level of field winding wire is spaced inwardly from back iron and flux interaction outer tip or top surface regions as shown respectively at  116 ′- 116 ″″ and  120 ′- 120 ″″. Because two windings are incorporated with each core member  82   a - 82   i  and if the windings are connected in parallel the current carried by each field winding is, in effect, reduced by 50% and, thus, the gauge thickness of the wire may be reduced proportionally. Also the machine winding time is greatly reduced because the axial length over which the winder must reach is cut in half in this embodiment.  
         [0047]      FIGS. 2 and 3  reveal that an electrically insulative, polymeric shield is positioned within each of the receiver troughs  132 ′- 132 ″″ intermediate the winding core and an associated field winding. In this regard, shields are shown in section in  FIG. 3  at  154   a - 154   i.  Shield  154   g  is revealed in position over receiving trough  132 ′ in  FIG. 2 . Similarly, shield  154   c  also is shown associated with module  110 .  FIG. 2  reveals shields  156   c  and  156   g  located within receiver trough  132 ″ in conjunction with module  111 . Shields  158   c  and  158   g  are revealed as installed within receiver troughs  132 ″′; and shields  160   c  and  160   g  are shown installed within receiver troughs  132 ″″.  FIG. 2  further reveals that that portion of the shield adjacent the back iron portion of the stator core member extends to an outer tip or top surface region and defines an outwardly open channel configured to carry lead out and lead in components of field winding wire. For a multiphase architecture, it is necessary to interconnect these windings and thus a non-interfering intercommunicating arrangement be developed. Note, that channels  162   c  and  162   g  are formed within respective shields  154   c  and  154   g.  Similarly, outwardly open channels are shown at  164   c  within shield  156   c  and at  164   g  in shield  156   g.  An outwardly open channel is seen at  166   c  in shield  158   c  and at  166   g  in shield  158   g.  Finally, an outwardly open channel  168   c  is formed within shield  160   c  and an outwardly open channel  168   g  is seen formed within shield  160   g.    
         [0048]     The receiving troughs and associated shields are configured to carry windings below the noted tip or top surface regions of the back iron portions and flux interaction portions and thus permit module stackability. Additionally,  FIGS. 2 and 5  reveal another feature of the device architecture, note that the winding core bottom surface regions identified at  130 ′- 130 ″″ are recessed inwardly from the associated flux interaction bottom surface regions  122 ′- 122 ″″ and back iron bottom surface regions  118 ′- 118 ″″. These recesses are provided to achieve the desired amount of winding core cross-section area. It may be recalled that the design of the motors calls for utilizing thicknesses and lengths for the modules  110 - 113  which are appropriate to avoid flux saturation phenomena and to incorporate a suitable safety factor. However, beyond those criteria no additional materials are utilized. Therefore, recesses may not be necessary and should not be considered limiting. Accordingly, the modular stacking design at hand within modules  110 - 113  is one permitting a highly efficient utilization of the pressure shaped processed ferromagnetic particles.  
         [0049]     Turning now to the configuration of the windings  150   a - 150   i  provided with modules  110  and  111 , reference is made to  FIG. 6 . In the figure, the windings at modules  110 - 111  are represented in general at  150  and the windings associated with modules  112  and  113  are represented in general at  152 . The three phases of these windings further are identified at branches A, B, and C and the winding positions are identified by the numeration 1, 2, and 3. These “Y” windings are connected in parallel. In this regard, note that phase A of windings  150  and  152  are commonly connected to line  180  which additionally is labeled as a phase “A”. Phase B of windings  150  is coupled to line  182 , while the corresponding phase B of windings  152  are coupled via line  184  to line  182 . Finally, phase C of windings  150  is coupled to line  186  while the corresponding phase C of windings  152  is coupled to line  186  via line  188 . Thus, phases A, B, and C at respective lines  180 ,  182  and  186  extend to the printed circuit board  66  as shown in  FIG. 2 .  
         [0050]     Referring to  FIG. 7 , the geometric aspect for the winding of one of these Y structures, for example, at  152  is schematically revealed. In the figure, the nine windings are identified in the manner of  FIG. 6 , i.e., being shown as C 1 , C 2 , C 3 , A 1 , A 2 , A 3 , and B 1 , B 2 , and B 3 . Lines  180 ,  182 , and  186  are reproduced in  FIG. 7  and the windings are represented showing clockwise rotation of the wire from the start lead to the center tap where the windings join in common as the center of the Y architecture. Now looking to the partial sectional end view of the motor  10  in  FIG. 8 , windings A 2  and B 2  are represented. The figure represents these windings from a schematic standpoint in the direction represented by the viewing directional arrow  190  in  FIG. 7 . Referring additionally to that figure, the start of the winding B 2  and, correspondingly the finish of winding B 1  is represented at  182 ′ in both figures. Note that the winding is within outwardly open channel  168   e.  Correspondingly, the start of winding A 2  and correspondingly the finish of winding A 1  is represented at  180 ′ extending from channel  168   e.  The finish of winding A 2  is represented in both figures at  180 ″ while the start of winding B 2  again is identified at  182 ′ exiting from channel  168   f.  Finally, the finish of winding B 2  is represented in  FIGS. 7 and 8  at  182 ″. The manufacturing procedures for carrying out these windings are substantially simplified and improved by virtue of the reduced axial winding length for each “Y” winding  152  and  150  as provided by the combination of modules  112  and  113  and  110  and  111 .  
         [0051]     This approach of achieving higher power motors through the combining of components or modules to form the field wound stator is uniquely suited to powder metal technology. Since the module design is optimized for uniting the requirements of the powder metal pressing industry and the electrical requirements of the motor design under consideration the total number of modules may vary. Also, the stacking ability of the modules yields a versatility to the motor design unavailable with a typical steel lamination motor design. Referring to  FIG. 9 , a version of the motor or electrodynamic apparatus limited to two modules is represented in general at  200 . The similarity of the architecture of device  200  with that of electrodynamic apparatus or motor  10  becomes immediately apparent. In this regard, the motor is configured with an aluminum cylindrical sleeve  202 , the ends of which are joined to cylindrical end caps  204  and  206 . A bearing  208  is mounted within end cap  204  adjacent a shaft opening  210 . Similarly, a bearing  212  is installed within end cap  206  adjacent opening  214 . Bearings  208  and  212  support motor shaft  213 , their inner raceways being rotatably engaged with respective shoulders  216  and  218  of the shaft. Shaft  213  is disposed about axis  280 . A wavy washer  220  loads the outer race of bearing  212  into appropriate position. Shaft  213  supports a rotor represented generally at  222  formed having an aluminum inner core  224 , a cylindrical back iron  226  and cylindrical permanent magnet or rotor pole region  228  extending outwardly to a cylindrical flux confronting surface  230 . The assemblage of end caps  204  and  206 , sleeve  202  and the shaft  213  is retained together, as before, by a sequence of machine screws, one of which is revealed at  232 .  
         [0052]     Motor  200  is configured with an annular stator assembly represented generally at  234 , the stator portion of which is formed of two annular modules formed of pressure shaped processed ferromagnetic particles and here represented in general at  236  and  237 . Note that the profiles of components  236  and  237  are identical to those described earlier at  110  and  111  or  112  and  113 . Using the identifying convention of the earlier figures, for a nine stator pole embodiment, stator pole core members  240   c  and  240   g  of module  236  are revealed. In similar fashion, core members  242   c  and  242   g  are illustrated in connection with module  237 . As before, each of these modules is net shaped with back iron portions as shown respectively at  244   c,    244   g  and  246   c,    246   g.  The back iron portions are integrally formed with the winding core portions of the stator pole core members as seen at  248   g  and  250   g.  Those winding core portions are, in turn, integrally formed with flux interaction portions as at  252   c,    252   g  and  254   c,    254   g.  These flux interaction portions extend to arcuate flux interaction surfaces as at  256   c,    256   g  in the case of module  236  and at  258   c,    258   g  for the case of module  237 . The surfaces define, with the flux confronting surface  230  of rotor  222  a functioning or working air gap  260 . Note that as in the case of earlier embodiments, both the back iron portions and flux interaction portions of the core components extend to coplanar top and bottom surface regions. The bottom surface disposed tip regions are located in mutual adjacency and alignment while the top surface regions extend to define receiver troughs as represented at  262   c,    262   g  for module  236  and at  264   c,    264   g  as illustrated in connection with module  237 . In each receiver trough, the winding core portions support a polymeric electrically insulative shield, each configured in the manner described above in connection with motor  10 . Note that polymeric shields  266   c,    266   g  are positioned within respective receiver troughs  262   c  and  262   g  while polymeric shields  268   c,    268   g  are located within respective receiver troughs  264   c,    264   g.  Field windings are shown, as before, at  270   c,    270   g,  the winding starts and finishes thereof being carried about the motor via outwardly open channels formed within the shields  266   c,    266   g  and  268   c,    268   g.  Those open channels are represented, for instant illustration at  272   c,    272   g  and  274   c,    274   g.  As before, motor  200  incorporates a sensible system having a disc form and represented generally at  276  which performs in conjunction with printed circuit board mounted control circuit sensors. Such a printed circuit board is represented in general at  278 . A preferred sensible system and sensor implementation for the motor as disclosed herein is described in a co-pending application for United States patent by Petersen entitled “Multi-Phase Motors With Single Point Sensing Based Commutation” (supra).  
         [0053]     As in the previous embodiment, winding core regions  284   g  and  286   g  are recessed to help achieve the desired electrical characteristics while retaining a suitable safety factor in overall winding core area. Additionally, some material and weight economies are also achieved. It should be noted that the recess  284   g  and  286   g  as well as recesses in the winding core bottom surface;  130 ′- 130 ″″ in the previous equipment are not required for proper or efficient motor assembly and may not be a necessary feature when designing for the optimum electrical characteristics, but are shown as an optional design feature available with pressed powder technology and suitable for many applications.  
         [0054]     Referring to  FIG. 10 , a motor or electrodynamic device represented generally at  300  is shown having an elongated architecture extending along its motor axis  302 . Device  300  represents a design wherein a stator assembly and associated rotor are of greater lengthwise extent along axis  302  as compared with the lengthwise extent of motor  200  along axis  280  ( FIG. 9 ). To achieve this desired extra length without excessive widthwise extents of the stator core components mandated by the above discussed pressed molding procedures, the stator is formed with three free-form components with lengths along axis  302  suited to achieve appropriate net shaping without excess thickness. As in the case of motors or electrodynamic devices  10  and  200 , motor  300  is formed with a aluminum cylindrical sleeve  304  the axially oppositely disposed ends of which are coupled with identical end caps  306  and  308 . End cap  306  is configured to support a bearing  310  at a shaft opening  312  and, correspondingly, a bearing  314  is mounted within end cap  308  adjacent opening  316 . Bearings  310  and  314  support a rotor shaft  318 , the shoulders of which at  320  and  322  are engageable with the bearing internal raceways. A wavy washer  324  functions to load the external race of bearing  314  inwardly. Shaft  318  supports a rotor represented generally at  326  having a cylindrical aluminum inner core  328 , the outer cylindrical surface of which supports a cylindrical rotor back iron  330 . Rotor back iron  330 , in turn, supports cylindrical permanent magnet  332  defining a sequence of, for example, six rotor poles and providing a flux confronting surface  334 . As before, the device assemblage is interconnected utilizing a sequence of machine screws, one of which is revealed at  336 .  
         [0055]     The stator assembly for motor or device  300  is represented generally at  338  and is seen to be structured having three pre-formed stator core module components  340 - 342 . Again utilizing the descriptive approach employed with motor or device  10  in  FIG. 2 , stator pole core members  344   c,    344   g  are shown in conjunction with module component  340 . Stator pole core members  346   c,    346   g  are shown associated with module component  341 , and stator pole core members  348   c,    348   g  are shown associated with module component  342 . Core members  344   c,    344   g  are shown formed integrally with respective back iron portions  350   c,    350   g.  Core members  346   c,    346   g  are shown formed integrally with respective back iron portions  352   c,    352   g,  and core members  348   c,    348   g  are shown formed integrally with respective back iron portions  354   c,    354   g.  These back iron portions are integrally formed with winding core portions extending therefrom. In this regard, core member  344   g  is shown having a winding core portion  356   g.  Core member  346   g  is shown having a winding core portion  358   g  and core member  348   g  is shown having an integrally formed winding core portion  360   g.  These winding core regions are formed integrally with flux interaction portions. In this regard, core members  344   c,    344   g  incorporate respective flux interaction portions  362   c,    362   g.  Core members  346   c,    346   g  incorporate respective flux interaction portions  364   c,    364   g,  and core members  348   c,    348   g  incorporate respective flux interaction portions  366   c,    366   g.  The flux interaction portions extend to define arcuate flux interactions surfaces. In this regard, flux interaction portions  362   c,    362   g  define respective flux interaction surfaces  368   c,    368   g.  Flux interaction portions  364   c,    364   g  extend to form respective arcuate flux interaction surfaces  370   c,    370   g  and flux interaction portions  366   c,    366   g  extend to form respective flux interaction surfaces  372   c,    372   g.  These flux interaction surfaces cooperate with the corresponding rotor flux confronting surface  334  to define a functional or working gap  374 .  
         [0056]     Each of the stator pole core members of each module  340 - 342  is configured with an inwardly depending receiver trough from each axial surface. For example, receiver troughs  376   c,    376   g  and  388   g  are formed within respective core members  344   c,    344   g  of module  340 . Centrally disposed core members as at  346   g  also are formed having an identical receiver trough as represented at  378   g  and  389   g,  and core members  348   c,    348   g  are seen to have respective receiver troughs  380   c,    380   g  and  390   g.  For the present embodiment electrically insulative polymeric shields are inserted over the winding core portion in the outboard or outwardly opening receiver troughs of the module assembly. In this regard, shields  382   c,    382   g  are inserted within respective receiver troughs  376   c,    376   g  and shields  384   c,    384   g  are inserted within respective receiver troughs  380   c,    380   g.  Shields  382   c  and  384   c  are seen to support a more elongate field winding  386   c.  Similarly, shields  382   g  and  384   g  are seen to support field winding  386   g.    
         [0057]     As illustrated on the C numerated side of  FIG. 10  the field winding encompasses all three stator pole core members  344   c,    346   c  and  348   c  coupling them together magnetically. The figure also reveals the formation of recesses on the bottom surfaces of each of the end module stator pole core members and on both surfaces of the center module. For example, such recesses are revealed at  378   g,    388   g,    389   g  and  390   g.  As before, the recesses function to permit fabrication of the winding core regions to satisfy the electrical design requirements of the motor and to an extent sufficient to avoid saturation and provide a reasonable factor of safety. Note that the recesses formed on the top and bottom surface regions of the winding core portion of each core member of each stator module are identical in this embodiment.  
         [0058]     Motor  300  also contains a sensible system represented as a disc at  392  which cooperates with a sensor arrangement and control circuit at a printed circuit board  394 .  
         [0059]     In the embodiment presented herein the individual stator core modules can be purposely slightly angularly misaligned or skewed within the cylindrical outer sleeve resulting in an offset between adjacent stator pole core members of adjacently stacked core modules yet still permitting the winding operation to occur in the same manner as if each individual stator core module was perfectly angularly aligned. This misalignment can be used in certain motor designs to reduce the effects of cogging or detent torque where desirable or required.  
         [0060]     As the instant electrodynamic apparatus structures reach larger sizes the module components forming the stator structure may themselves be segmented, again to accommodate for the severe molding requirements at hand as well as to facilitate the winding of field coils about the winding core regions. One such segmentation approach is illustrated in connection with  FIGS. 11 and 12 . Looking to  FIG. 11 , a motor represented generally at  400  is shown in a sectional portrayal similar to that seen in  FIG. 3 . In this regard, the section is taken through a module component represented generally at  402  and seen additionally in perspective fashion in  FIG. 12 . Component  402  is formed with nine stator pole core member assemblies represented generally at  404   a - 404   i.  Stator pole assemblies  404   a - 404   i  are formed with corresponding pressed powder net shaped stator pole core members represented generally at  406   a - 406   i  as seen additionally in  FIG. 12 . Each of the core members  406   a - 406   i  is formed, as before, integrally with back iron portions  408   a - 408   i  from which emanate the winding core portions shown respectively at  410   a - 410   i  which, in turn, are integrally formed with respective flux interaction portions  412   a - 412   i.  The flux interaction portions  412   a - 412   i  extend respectively to arcuate flux interaction surfaces  414   a - 414   i.  A rotor is represented generally at  416  structured in the same manner as rotor  44  described in connection with  FIGS. 1-3 . This rotor extends to a flux confronting surface and is spaced from flux interaction portions  412   a - 412   i  to define a working or functional gap  420 . Component retention is provided by a sequence of machine screws in the same manner as described in connection with motor  10 . In this regard, sectional representations of three such machine screws are provided at  421 - 423 .  
         [0061]     Note that component  402  is not net shaped as a unit but is pre-formed in three arc shaped segments which are joined together in mutual abutment at edge locations  426 - 428 . This form of abutment is intimate and touching inasmuch as the resultant three segments reside in flux transfer communication. Three segments are maintained in their arch-like structural orientation by the outer cylindrical sleeve  430  seen in  FIG. 11 . The three segments, identified in general at  432 - 434  are seen in  FIG. 11  to be associated with insulating sleeve and field winding combinations  436   a - 436   i.  Preferably, the field windings are mounted upon the stator pole core members  406   a - 406   i  as they exist in the segments  432 - 434 . In certain rotor pole, stator pole, pair arrangements such as a nine pole stator and an eight pole rotor the three windings of each phase are wound on adjacent poles meaning A 1 , A 2 , A 3 , B 1 , B 2 , B 3  and C 1 , C 2 , C 3  as one proceeds around the stator. This winding form could be enhanced with the stator arrangement of  FIGS. 11 and 12  since the multiple stacked core components or modules of a single phase could be pre-wound prior to assembly into sleeve  430 .  
         [0062]     Note additionally in  FIG. 12  that alignment notches are provided, for example as shown at  438  and  440  in segment  433 . The figure further reveals the provision of receiver troughs  442   a - 442   i  at respective winding core portions  410   a - 410   i.    
         [0063]     Looking to  FIGS. 13 and 14 , an architecture is presented wherein a single component is formed of nine segments in a nine stator pole assembly configuration. This form of construction would only be applicable on larger motor types since assembly of multiple segments is first required prior to assembly of the stacked modules to complete a single stator assembly such as shown in  FIGS. 9 and 10 . In  FIG. 13 , motor or device  500  is represented in sectional format in the manner of FIGS.  3  and  11 . Correspondingly,  FIG. 14  shows in perspective a multi-segmented module which is provided in conjunction with the sectional locations on the motor  500  shown in  FIG. 13 . Looking to that figure, motor or device  500  is seen to be comprised of nine distinct stator pole assemblies  504   a - 504   i.  As represented additionally in  FIG. 14 , these stator pole assemblies  504   a - 504   i  are configured with corresponding and respective stator pole core members  506   a - 506   i.  As before, each of the stator pole core members  506   a - 506   i  is formed integrally with a back iron portion as represented in  FIG. 13  respectively at  508   a - 508   i.  Integrally formed therewith and extending radially inwardly from the back iron portions  508   a - 508   i  are respective winding core portions  510   a - 510   i.  These winding core portions which are recessed as seen in  FIG. 14 , extend radially inwardly to and are formed integrally with flux interaction portions shown respectively at  512   a - 512   i.  The flux interaction portions  512   a - 512   i  extend radially inwardly to define arcuate flux interaction surfaces shown respectively at  514   a - 514   i.    
         [0064]     The rotor of motor or device  500  is represented in general at  516  and is configured in the same manner as rotor  44  described in connection with  FIGS. 2 and 3 . The rotor extends radially outwardly to provide a flux confronting surface  518  which in turn, cooperates with flux interaction surfaces  514   a - 514   i  to define a working or functional gap  520 . Each of the stator pole core members  506   a - 506   i  is provided with a polymeric electrically insulative shield over the winding core portion interfacing with the associated winding combination as shown in general at  522   a - 522   i  within respective stator pole assemblies  504   a - 504   i.    
         [0065]      FIGS. 13 and 14  reveal that the module  502  is formed of nine discrete segments, the edges of the back iron portions of which are abutted together in flux transfer relationship at nine locations shown at  524 - 532 . Thus, each segment is configured with a singular component stator core assembly. In this regard, it may be recalled that at least two axially stacked modules are called for in this axially modular form of optimized large motor construction. As in the case of component  402  described in connection with  FIGS. 11 and 12 , the segments are assembled in compression along their back iron portions to evolve an arch form of structure exhibiting desirable structural integrity. The back iron components are retained in their appropriate orientation by cylindrical sleeve  544  seen in  FIG. 13 . As described in connection with motor  10 , motor  400  module components, end caps and cylindrical sleeve are retained in position by a sequence of three machine screws, sectional representation of which are shown in  FIG. 13  at  534 - 536 . It should be noted that there are other suitable means of securing the final assembly of the end caps and the stator module assemblies other than the aforementioned machine screws and therefore their use in the embodiments presented herein should not be considered in a limiting sense. One segment, for example, that representing a back iron portion and a stator pole core member  506   e  is configured having alignment notches as at  538  and  540  to aid in assembly of the entire stator core as described in connection with  FIG. 5 . Note additionally in  FIG. 14  that the motor axial length of the winding core portions  510   a - 510   i  is diminished, inter alia, to define receiver troughs shown respectively at  542   a - 542   i.    
         [0066]     Since certain changes may be made in the above-described apparatus and method without departing from the scope of the invention herein involved, it is intended that all matter contained in the description thereof or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.