Abstract:
A number of embodiments of rotating electrical machines and methods for winding them that provides a high space utilization and very effective winding with less likelihood of damage to the insulation of the wire of the winding during the winding process. The arrangement basically does not require the winding needle to be moved back and forth in the slot between the poles but rather employs insulating inserts that are positioned on the axial faces of the poles outside of the gaps for guiding the wire from one end to the other so as to provide the high space utilization. In one embodiment the insulating insert effectively changes the circumferential length of the coil winding that decreases in an axial direction along their length.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a division of our application, Ser. No. 10/064,362, Filed Jul. 6, 2002, now issued as U.S. Pat. No. 6,831,389 on Dec. 14, 2004, which application is a continuation in part of our application Ser. No. 09/683,764, Filed Feb. 12, 2002, now issued as U.S. Pat. No. 6,590,310 on Jul. 8, 2003, all assigned to the assignee hereof. 

   BACKGROUND OF INVENTION 
   This invention relates to a method of making a stator coil structure for a rotating field electrical machine and more particularly to an improved coil method of forming such a device that will provide high efficiency and compact size. 
   Most rotating electrical machine are comprised of relatively rotatable rotors and stators. One of the rotor and stator carries a plurality of spaced permanent magnets that cooperate with electrical coil windings formed on the other of these members. It is the formation of the electrical coil windings that determines in large part the efficiency of these types of machines. Generally, the winding mechanisms and methods previously proposed have been something less than totally efficient and have at times resulted in very expensive methods and resulting products. This can be best explained by a description of the various types of structures and methods that have been employed for the coil windings. Generally there have been five methods of winding the coils. The first method may be characterized as a “direct winding” method wherein a transverse oscillating system is provided and a winding in the form of an enameled wire is wound around the magnet pole tooth of the core using a needle through which the winding is passed. The winding is wound adjacent the magnetic pole tooth and two upper and lower winding guides slide alternatively between the poles to deposit the windings on them. Alternatively the needle is reciprocated in the slot between the pole teeth and directly winds the wire onto the teeth. 
   The disadvantage with this type of winding method is that the needle for winding the wire must be placed into the slot from the open end thereof and or the guides must move into this area requiring a dead space between adjacent windings. This restricts the winding density and lowers the space factor thereof. Even when winding guides called formers are employed, the winding lacks alignment and it is difficult to increase the winding density. It is also difficult to apply this method to a stator having a large number of magnetic pole teeth or a revolving field type coil having a small inside diameter. Furthermore, the winding device is complicated in structure and becomes quite large. 
   When winding guides (formers) are used the resulting rubbing contact with the wire can strip or damage the insulating enamel coating and decrease the electrical efficiency. 
   In connection with an inner rotor type a stator core is divided into radially protruding portions with a continuous inner periphery and an outer peripheral core is fitted thereon. One way in which this type of device is made is that a coil is wound around a bobbin on the protruded portions. Then the outer peripheral core is fitted after the coil winding. This is called a bobbin winding method. Another way the inner rotor type is made, is that the windings are wound directly on a core having radially protruding sections with an insulating material interposed there between. Then the outer peripheral core is fitted thereon. This is called an outer winding method. 
   The disadvantages with this second type of construction is that the divided core must be fitted together so that dimensional accuracy is maintained and also to prevent subsequent separation of the parts. Also, the coils must be prevented from bulging out to the outer periphery of the device. This results in complexity in the structure and low production efficiency. 
   With the bobbin winding method, the winding may deform the bonding flanges and the winding density cannot be enhanced. In addition interference with the outer peripheral core and the dead spaces at the flanges thereof prevent the winding density from being enhanced. In this case, there are deficiencies of lowering the space factor as with the first mentioned method. 
   A third type of winding method uses divided pole cores. In this case, the armatures are formed as segments, each having a respective pole tooth. Each pole tooth is wound and then the individual segments are fixed together in a suitable manner, normally by welding using a laser beam. This method is not only expensive but raises problems in connection with the dimensional accuracy and the costs involved with the extra steps. 
   A further method employs what is called a “sawing” method. In this case, a solid core is employed having a plurality of teeth. A needle is passed sequentially through the slots between the magnetic pole teeth in a back and forth sawing motion to wind the winding. This method has the same disadvantages as the first method step described. Also high stresses are placed on the wire that can result in breakage or rupturing of the insulation. 
   Another method is the so-called “armadillo” type method. In this case, the core is formed in a circular shape and then deformed into a linear shape as used with a linear motor. The winding is then placed on the cores and then the device is again joined by welding the previously cut ends. Again, this method has problems of dimensional accuracy and also because of the stresses exerted on the windings during the successive curving operation, reliability is considerably decreased. 
   Another type of mechanism for winding employs a needle that is held outside of the slot between the armature teeth at one end of the core and a cam shaped member is provided for reciprocating the winding onto the core. These methods also have considerable disadvantages. In this type of mechanism, the holding and releasing mechanism for the winding is very complicated and the winding action must be repeated during each turn so that rapid productivity is not possible. In addition, the repetition of holding and releasing does not insure good alignment. Even though the needle never enters the slots, a mechanism for introducing the windings into the slots is needed. When this is done, the insulation on the windings may be disturbed. 
   Thus, the conventional rotating machine presents a problem in that the stator should having windings of a large diameter to permit low voltage and large current to obtain high power. In addition, a large number of magnetic pole teeth are desirable to reduce cogging and to provide smoother rotation and better efficiency. This again results in difficulties in forming the winding. 
   It is, therefore, a principal object to this invention to provide an improved winding method for coil assembly for a rotating machine wherein accurate coils can be formed having a high density with minimum gaps between the coil windings of adjacent pole teeth. 
   It is also an object to the invention to provide a method wherein the efficiency of such a machine can be significantly improved. 
   Our first identified, aforenoted co-pending application discloses a number of embodiments that achieve these objects. However there is still a possibility of obtaining of further advantages. With all of the embodiments therein tapered insert pieces are employed for guiding the Wire toward the opposite end of the pole from the needle. The height of the end of the tapered insert pieces in the area of the needle limits the number of possible windings in this area. Thus maximum winding density is somewhat compromised. 
   It therefore is a principle object of this invention to provide a method using insert pieces that achieve the objects of our aforenoted application and which offer the possibility of even greater winding density. 
   SUMMARY OF INVENTION 
   This invention is adapted to be embodied in a method of winding the coils of a rotating electrical machine. In this method, a circular core of magnetic material with a plurality of magnetic pole teeth extending radially from the circular core is provided. Each of the magnetic pole teeth defines a core and slots formed there between. Each of the slots defines a mouth that is formed between adjacent outer ends of the cores. The winding method comprises the steps of positioning a threading needle having an opening through which the wire for the winding of the coils is fed into proximity to one of the mouths. The needle opening is moved in a path around one of the pole teeth and at one side of the slot without moving the needle in any substantial distance along the length of the one pole tooth to form a first winding. The movement of the needle opening is continued in a path around the one of the pole teeth at the one side of the slot without moving the needle in any substantial distance along the length of the one pole tooth to form succeeding windings. The circumferential length of the pole teeth decreases in an axial direction along their length and the wire end is held at the end of the pole tooth spaced from the needle so that each successive winding forces the previous winding along the pole tooth toward the circular core without requiring movement of the needle in any substantial distance along the length of the one pole tooth so that the needle not be moved any substantial distance into the slot. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a cross sectional view taken through a rotating electrical machine formed in accordance with one embodiment of the invention and made employing one of the methods disclosed herein. 
       FIG. 2  is an enlarged, exploded perspective view of a portion of the insulator of the magnetic core arrangement. 
       FIG. 3  is an end elevational view of the laminations of the magnetic core looking from one side. 
       FIG. 4  is a side elevational view of the core. 
       FIG. 5  is end elevational view of the core looking in the opposite direction from  FIG. 3 . 
       FIG. 6  is an end elevational view, in part similar to  FIG. 3 , but shows the construction with the insulator in place with one portion of the insulator shaded to show how the side of the insulator is tapered. 
       FIG. 7  is a side elevational view, in part similar to  FIG. 4 , but shows the core assembly with the insulator in place. 
       FIG. 8  is an end elevational view, in part similar to  FIG. 5  looking in the opposite direction from  FIG. 6  and showing one portion of the insulator shaded to show how the side of the insulator is tapered. 
       FIG. 9A  is an end elevational view looking in the same direction as  FIGS. 3 and 6  and shows the individual coil windings in place. 
       FIG. 9B  is a schematic electrical diagram showing the coil windings. 
       FIG. 10  is a cross sectional view taken along a radial plane through the insulating material and insert and showing the configuration thereof. 
       FIG. 11  is a cross sectional view, in part similar to  FIG. 10 , and shows another embodiment. 
       FIG. 12  is a cross sectional view, in part similar to  FIGS. 10 and 11 , and shows a third embodiment. 
       FIG. 13  is a view looking in the direction perpendicular to  FIGS. 10 through 12  and shows the shape of the insulator surface along the planes a, b and c of those three figures. 
       FIG. 14  is a view, in part similar to  FIGS. 10 ,  11  and  12  and shows yet another embodiment of the invention. 
       FIG. 15  is a cross sectional view, in part similar to  FIGS. 10 ,  11 ,  12  and  14 , and shows yet another embodiment of the invention. 
       FIG. 16  is an enlarged end view showing one set of the windings and illustrating how they are formed and is basically an enlarged portion of  FIG. 9A . 
       FIG. 17  is a view, in part similar to  FIG. 6 , and shows how the winding needle is associated with the slots between the pole teeth during the winding operation. 
       FIG. 18  is a projected side elevational view showing the path the needle takes when winding one of the coil. 
       FIG. 19  is a side view looking in a direction perpendicular to  FIG. 21  and showing the same paths of travel of the winding needle. 
       FIG. 20  is an enlarged view showing how the finished coil windings and illustrating the dimensional aspects thereof. 
       FIG. 21  is a perspective view showing one embodiment of the invention and associated with a single of the armature teeth. 
       FIG. 22  is a perspective view, in part similar to  FIG. 21 , and shows another embodiment of the invention. 
       FIG. 23  is an enlarged view showing an embodiment of a needle in association with two of the pole teeth in accordance with of the invention. 
       FIG. 24  is a view, in part similar to  FIG. 23 , and shows another embodiment. 
       FIG. 25  is a view, in part similar to  FIGS. 23 and 24 , and shows yet another embodiment. 
       FIG. 26  is an exploded perspective view, in part similar to  FIG. 2 , and shows another embodiment of the invention. 
       FIG. 27  is a view, in part similar to  FIG. 20 , but showing the resulting wiring of the embodiment shown in  FIG. 26 . 
       FIG. 28  is an exploded perspective view, in part similar to  FIGS. 2 and 26 , and shows a further embodiment of the invention. 
       FIG. 29  is an end view, in part similar to  FIG. 16 , but shows the winding in accordance with the embodiment of  FIG. 28 . 
       FIG. 30  is a partial side elevational view in part similar to  FIGS. 16 and 19  and shows a still further embodiment of the invention. 
       FIG. 31  is a cross sectional view of one of the poll teeth of this embodiment with the coil winding removed. 
       FIG. 32  is a partial end elevational view taken in the direction of the arrow  32  in  FIG. 31 . 
       FIG. 33  is a cross sectional view of the upper bobbin half taken along the same plane as  FIG. 31 . 
       FIG. 34  is an end elevational view taken in the direction of the arrow  34  in  FIG. 33 . 
       FIGS. 35   a – 35   k  are a series of cross sectional views taken at equal intervals along the length of  FIG. 33  starting at the base of the pole tooth (left hand side) and ending at the tip (right hand side) thereof. 
   

   DETAILED DESCRIPTION 
   Referring now in detail to the drawings and initially primarily to  FIGS. 1 through 8 , a rotating electric machine constructed in accordance with the invention is identified generally by the reference  31 . The rotating electric machine  31  may be either an electric motor or a generator depending upon the desired application. 
   The rotating electrical machine  31  is comprised of a stator assembly, indicated generally by the reference numeral  32 , and a rotor assembly, indicated generally by the reference numeral  33 . These components are contained within a housing assembly that is comprised of a cup shaped, main housing piece  34  and a cover plate  35 , which is suitably attached thereto to form an enclosure  36  in which the stator assembly  32  and rotor assembly  33  are positioned. 
   The rotor assembly  33  is formed with a central portion  37  on which a plurality of circumferentially spaced permanent magnets  38  having alternating polarity are affixed in a known manner. The end portions of the rotor assembly  33  comprise shaft portions  39  and  41  that are journalled, respectively, in bearings  42  carried by an integral closure wall  43  of the cup shaped, main housing piece  34  and bearings  44  carried in a recessed portion  45  of the cover plate  35 . 
   The construction of the rotor assembly  33  may be deemed to be of the general conventional type and any type known in this art might be employed. Also, although the described machine employs an arrangement wherein a coil winding assembly, indicated generally by the reference numeral  46  is provided on individual armature poles, to be described, formed on the stator assembly  32 , it should be understood that the coil winding assembly  46  can be mounted on the rotor assembly  33  and the permanent magnets  38  may be mounted as part of the stator assembly including the cup shaped, main housing piece  34 . 
   The stator assembly  32  is comprised of an armature core, indicated generally by the reference numeral  47 , which is made up of a plurality of laminated armature plates as shown in  FIGS. 3 through 5 . In this embodiment, since the armature core  47  is the outer element of the rotating electric machine  31 , it is comprised of a circular portion  48  from which a plurality of pole teeth, each indicated generally by the reference numeral  49 , extend. The pole teeth  49  have generally rectangular portions  51  that extend outwardly from the circular portion  48  and which terminate in enlarged, projecting ends  52 . Gaps  53  are formed between adjacent ends of these projecting ends  52 , which form the outer termination of slots  54 , formed between adjacent pole teeth  49 . 
   In order to assist in the alignment of the lamination of the core pieces of the armature core  47 , each of them is formed with a reference slot  55  on the outer periphery of their circular portion  48 . This slot  55  assists in alignment as well as location within the cup shaped, main housing piece  34 . 
   The ends of the slots  54  adjacent the circular portion  48  of the armature core  47  is defined by angularly disposed surfaces  56  formed on opposite sides of the bases of each of the pole teeth  49 . These act as projections that cooperate with the projecting ends  52  at the outer ends of the teeth  49  so as to assist in locate an insulating bobbin forming members  57  around which the coil winding assembly  46  is formed as well as locating the individual windings themselves. 
   Referring now to  FIG. 2 , the construction of the insulating bobbin forming members  57  will be described. This is comprised of right and left hand sections  57 A and  57 B, which have a substantially identical construction, except as will be hereinafter described.  FIG. 2  is a typical view of the insulating bobbin forming member  57  regardless of the side involved. Like the armature core  47 , the insulating bobbin forming member  57  is comprised of a circular portion  58  that has an L-shaped cross section and from which extend individual legs  59  of a generally U-shape which is complimentary to and snuggly received on the core pole teeth  49 . Inclined surfaces  60  at the base of these legs  59  cooperate with the aforenoted angularly disposed surfaces  56  formed at the outer ends of the pole teeth  49  so as to provide a stop or abutment against which the coil windings actually engage. This construction also facilitates alignment. 
   As may be seen in  FIGS. 6 through 8 , the outer periphery of the circular portion  58  of the insulating bobbin forming member  57  extends to a lesser circumferential extent than the outer periphery of the circular portion  48  of the armature core  47 . 
   At the outer periphery of the insulator legs  59  and in the area between the slot gaps  53 , the insulating bobbin forming member  57  have axially extending flange portions  61 . These flange portions  61  are substantially co-extensive with the projecting ends  52  of the armature core portions  51 . In addition, an arcuate portion  62  interconnects these axially extending flange portions  61  and extends axially outwardly so as to provide an abutment against which the coil winding assembly  46  will be confined as hereinafter noted. Preferably the arcuate portion has a thickness or height of S c  that is equal to or greater than one half of the width of the slot S c . 
   Further projections, indicated at  63 , are formed at circumferentially spaced locations around the periphery of the insulating bobbin forming member  57 , at least one of which is aligned with the insulator leg portion  59  and another of which is positioned adjacent the intersection between the inclined surfaces  60  as best shown in  FIGS. 2 and 6 . This construction is formed at one side of the insulator on one of the insulating bobbin forming member  57 A or  57 B. The spacing of these projections is chosen in order to facilitate the passage of wires connecting the individual coils of the coil winding assembly  46  as will become apparent. On the other side, there are similar further projections, indicated at  64 , which may form a similar purpose. 
   In accordance with an important feature of the invention, special insulator inserts indicated by the reference numeral  65  are placed on the faces of the insulator legs  59  on one or preferably both of the insulators in the area between the respective arcuate portions  62  and further projections  63  and  64  thereon. These insulators are shown in lines in  FIGS. 6 and 8  so as to indicate their relationship to the respective insulating bobbin forming member  57 A or  57 B. 
   The shape of these insulator inserts  65  may be of any of the configurations shown in  FIGS. 10 through 12 ,  14  or  15 . Basically, the configuration is such so that the inclination is in a generally downward direction from the outer peripheral edge of the respective pole tooth  49  toward the base thereof where it meets the circular portion  58 . The purpose of this will be described in more detail shortly. Basically the shape is designed so as to promote the slipping of the wires radially outwardly from the outer periphery of the pole teeth  49  and specifically the rectangular portions  51  thereof toward the circular portion  58 . 
   It should be noted that the further projections  63  and  64  need not be formed at the base of each of the pole teeth  49  because of the inclined surfaces  60  formed thereat which will tend to preclude the wire from slipping down along the incline below that point. However, the further projections  63  form a further purpose than stopping the wire coils from slipping down beyond this point as will become apparent. 
   Referring now specifically to the outer configuration of the various embodiments,  FIG. 10  shows an embodiment wherein the insulator insert, indicated at  65 A, is convexly curved from the radially inner end of the coil winding to the radial outer end. This curvature is when viewed in the radial direction as in  FIG. 10 . Looking in a perpendicular direction, as seen in FIG.  13 , it will be seen that the curvature in this axial direction increases from one end to the other as shown by the section lines a, b and c. 
   In the embodiment of  FIG. 11 , the shape of the insulator insert, indicated by the reference numeral  65 B, is not a convex curve as shown in  FIG. 10  but is in a concave curve. The curvatures in the other (axial) direction are the same as those shown in  FIG. 13 , however. 
   It is also not necessary that the curvature extend the full length of the coil winding.  FIG. 12  shows an insulator insert  65 C wherein the inclination stops short of the end of the leg portion  59  and short of the inclined surface  60 . However, it is preferable to have this short area not be too great. 
     FIGS. 14 and 15  show other configurations for the insert pieces that are particularly adapted for use with winding methods utilizing needles, which will be described later in connection with  FIGS. 23 through 25 . In these embodiments, the arcuate portion  62  at the radially inner end of the pole teeth  49  and specifically their rectangular portions  59  is provided with a curved or rounded edge  66  which leads downwardly toward an inclined insulator insert  65 D. In this case, the inclination is linear in axial planes and nevertheless curved in radial planes as shown in  FIG. 13 . 
     FIG. 15  shows another inclined insulator insert  65 E which has a stepped configuration consisting of a first, more steeply inclined portion  67  adjacent the end of the rounded edge  66  and then a second, more gradually inclined portion  68  that extends to the radially outer end of the respective tooth. Of course, other configurations also are possible. 
   In the embodiments of  FIGS. 14 and 15  it is also possible to extend the upper end of the projections  62  in a radial direction as shown by the light line areas  62 A in these figures to provide a wire guide so that the winding needle, to be described later, can be spaced radially inwardly from the gaps  53 . If necessary for clearance purposes when the machine  31  is assembled or running these wire guides  62 A may be cut off after the winding operation has been completed. 
   Although the various inclined insulator members have been described as separate pieces, they may be detachably affixed to the insulating bobbin forming members  57  or integrally formed thereon. 
   It has been noted that there is a coil winding assembly  46  formed on the pole teeth  49  of the armature core  47 . Although any winding pattern may be employed, a typical winding pattern that can be utilized in conjunction with the invention is shown in  FIGS. 9A and 9B . In this particular winding, there is a three-phase, three pole series of windings resulting in a total of nine (9) armature pole teeth  49 . 
   One possible winding arrangement is shown in these two figures wherein each of the phases U, V, and W have their coil windings formed on adjacent poles with a common connection C. Each coil winding is comprised of a forward winding, a reverse winding and a forward winding indicated by the reference characters F, R and F. 
   As may be seen in  FIG. 9A , the insulator further projections  63  hold the ends of the windings for adjacent coils and space them outwardly both axially and radially from the winding of the individual coils to form a cross over area indicated by the reference numeral  70  which appears in  FIGS. 1 and 9A . By so locating these cross over wires, it is possible to make the coil windings more compact, as will become apparent from the following description. 
     FIG. 16  is an enlarged view of the V-phase of the windings and shows the structure in more detail. In this figure, the individual strands of wire are indicated by the reference numeral  69 . 
   The method by which the winding is accomplished may be best understood and will now be described by reference primarily to  FIGS. 17 through 19 . The winding apparatus includes a needle carrier  71  that carries a winding needle  72  having a suitable configuration, examples of which will be described later by reference to  FIGS. 22 through 25 . The needle carrier  71  and needle  72  are formed with a wire guide opening  73  through which the individual enameled wire strand  69  passes from a feed roll  74 . The path of wire travel is indicated by the arrows R in  FIG. 19 . 
   Initially, one end of the wire is clamped by a clamp at the position shown at X in  FIG. 19 , this being disposed radially outwardly beyond the end of the armature core  47  to forms one end of one of the coil windings of the coil winding assembly  46 . The needle is then moved radially along the tooth but in an area, which is disposed outside of the slots  54  between the teeth and on one axial side thereof. In this way, when the windings are formed, the bulging portion that overlies the wire end will not fill the slots  54  but will be positioned in an axial direction outwardly from these gaps and along one side face of the individual pole teeth  49 . 
   The needle carrier  71  generally moves in a rectangular pattern around the individual pole teeth  49  and their overlying insulating bobbin forming members  57  as seen in  FIG. 18 . The winding needle  72  also rotates, as shown by the arrow in  FIG. 17 , through an arc W as it encircles the individual pole tooth  49 . As will become apparent later, during winding, the needle  72  can either be radially positioned in the area immediately inside of the slot  54  in the area formed in the gaps  53  between the projecting ends  52  at the ends of the pole teeth  49 , or radially inwardly of this area as long as during the winding operation the wire will contact the inner edge of the arcuate portion  62  of the insulating bobbin forming member  57 . 
   As the wire is wound, it will be trapped by these edges and will engage the axially outermost portion of the insulator insert  65 . Thus, as the needle traverses the path shown by the arrows P in  FIG. 18 , the wire strands  69  will be engaged with the axial outermost portions of the insulator insert  65 . After traversing this area, then the needle  72  and needle carrier  71  is moved in the area indicated by the arrows Q in the radial direction between the adjacent pole teeth  49  and specifically the area of the slots  54 . 
   As each winding is completed, the next winding will engage the previous winding and force it down the incline of the insulator insert  65  so that the wires will collect at the radial outer periphery of the slots  54 . There the wire will be restrained by the inclined surfaces  60  of the insulating bobbin forming members  57 . 
   Then, the next series of windings is made and the resulting winding will appear as shown in  FIG. 20 . As seen in this figure, there is provided a very neat winding without bulges and which occupies substantially one half at the gap between the pole teeth  49  in the slots  54 . This provides a very dense coil and insures maximum output of the machine. 
   Although only one needle carrier  71  and needle  72  is illustrated, preferably several can be provided at circumferentially spaced locations to speed up the winding process. For example there can be provided three of such assemblies, one for each winding phase. They can all be winding at the same time. 
   It has been noted that one end of the winding is held in the clamp at the position X as shown in  FIG. 19 . It may be that after each winding is completed, it would be helpful to provide a projection or post, indicated by the reference numeral  75  as shown in  FIG. 21  at the base of the insulator assembly. The wire is looped around the projection  75  before the next winding on the individual pole teeth  49  is performed. This will assist in pulling the wire out toward the outer periphery of the winding adjacent the inclined surfaces  60  of the insulator. Also, similar posts  76  may be positioned on the arcuate portion  62  of the insulators and pole teeth, although this may not be necessary. 
   One form of needle and winding method is shown in  FIG. 23 . In this case, the needle  72  can pass in the area of the gap  53  between the pole teeth at the outer periphery of the slots  54 . 
   In another embodiment, as shown in  FIG. 24 , the needle need not be positioned in the slot  54  but only the gap  53  between the pole teeth. This particular arrangement is useful with the configurations shown in  FIGS. 14 and 15  where the round  66  will smoothly guide the wire strand  69  down to the insulator insert  65 . 
     FIG. 25  shows another needle form wherein the needle has an enlarged end portion and actually is disposed in the gap  53 . Again, however, this will be in the area where the winding will be the least and will not obscure the filling of the remaining portion of the slot  54  with coil winding. This also permits the outer opening  73  of the needle  72  to be formed with a round as shown in this figure. This further protects the enameled insulation of the wire strands  69  from damage. 
   It should be noted that the winding method described is very effective in ensuring that the needle or the windings do not engage each other so that the insulation on the individual wires will not be scraped off and good density can be achieved. 
   This can further be improved by utilizing an insulator, indicated generally by the reference numeral  77  in  FIG. 26 , and which has the structure basically the same as that previously described. Where the portions of the structure are the same, they have been indicated by the same reference numerals. 
   In this embodiment, however, the area between the inclined surfaces  60  at the radially outer periphery of the slot  54  is formed with a dividing wall  78 . This dividing wall  78  lies in the area where the needle  72  will not pass but nevertheless will hold the wires at the outer periphery of the pole teeth individual leg  59  in separated form so as to result in a winding as shown in  FIG. 27  which further improves the density and, at the same time, eliminates the possibility of interference between the windings on adjacent pole teeth  49 . 
     FIGS. 28 and 29  show another embodiment wherein instead of the dividing wall  78 , there is provided a tab like projection  79  that carries a guide post  81 . The guide post  81  may be used to loop the end of one winding toward the other and will assist in maintaining a more compact assembly and again improves the density. 
   After the desired of the winding methods have been performed utilizing the preferred insulator construction and needle configuration, a controller assembly of any desired type  82  ( FIG. 1 ) is mounted on the further projections  64  of the insulating bobbin forming member  57 A. 
   The foregoing description includes and was taken from our aforenoted first mentioned co-pending application. As already noted, although those embodiments represent a considerable advance in the art, further improvements are possible.  FIGS. 31–35  show one form such further improvements may take. 
   Referring now to these figures and this added embodiment of the invention, only a section of the stator is shown as the remainder of the machine may be of any type including those previously described. Also where parts are the same as the embodiment of  FIGS. 1–10 , they have been identified by the same reference numerals and will be described further only where necessary to permit those skilled in the art to practice this embodiment. 
   In this embodiment adjacent coil windings  46  interconnected by crossover wires  66  passed in the slots  54  formed between the pole teeth  51 . In this coil structure, the coils  46  are wound around the stator of the three-phase motor having three phases of UVW continuously formed with the coils wound alternately in opposite directions as shown in  FIG. 9 . 
   For such coils wound alternately in opposite directions, the coils  46  are continuously formed between the adjacent magnetic pole teeth  51  so that the crossover wires  66  are disposed between the coils  46  formed on the adjacent magnetic pole teeth  51 . Thus, even if the crossover wires  66  are disposed across the slots  54 , the needles are not passed through the slots in winding the coil as described before ( FIGS. 18 and 19 ), thereby preventing the crossover wires  66  from being damaged or broken by the contact with the needle. 
   The crossover wires  66  are disposed through the slots  54  in such a manner, whereby there is no need to form a protrusion for hooking a crossover wire as in the previous embodiments so that the insulator structure is simplified and wiring can be easily carried out by saving the crossover wires from being hooked on the protrusions to be disposed in forming the coil. Also, the wiring length becomes shorter, which may result in reducing wiring resistance. 
   In the above embodiment, the tapered members  65  are used as a wound wire transfer means to slide the windings wound around the protruding end side of the magnetic pole teeth down to its root side without inserting the needle into the slot. However, the coils can also be wound around the magnetic pole teeth from their root sides by using circumference changing members  101  in lieu of such taper members, or by controlling the looping action of the needle to provide slack in the windings as it is drawn out, and thus sliding the windings down to the root sides. 
   As seen best in  FIGS. 31–35  a circumference changing member  101  according to the invention is used in place of the before-mentioned taper members  65 . The circumference changing member  101  may be a separate member from the insulating bobbin forming members  57  or a member molded integrally therewith. 
   As shown best in  FIG. 35 , the circumference changing member  101  is chamfered as indicated at  102  at its opposite ends on the upper surface wherein the amount of this chamfering is gradually increasing from the positions of (a) through (k) toward the outer periphery. This gradually shortens the surface length of the circumference changing member  101  and accordingly the length or circumference around which each turn of the coil winding  46  makes progressing toward the tips of the pole teeth  51 . 
   Gradually shortening the circumference in such manner allows a drawing support point of the winding that is drawn out of the needle to be disposed on the outer periphery side and allows the winding to easily slide outward when the winding is wound around the inner periphery side as seen ion  FIG. 29 . Therefore, the needle winding action outside of the slot  54  (out of the inner periphery side in this example) or adjacent the inlet of the slot  54  without inserting the needle into the slot  54  allows the winding to be wound on the magnetic pole tooth  51  to the bottom side of the slot  54 . In this case, as to the needle winding action, it is desirable to increase trail displacement of the loop to the extent of providing slack in the winding in order to carry out the winding action. 
   Thus, the drawing support point of the winding drawn out of the needle is located at the bottom of the slot to provide slack in the winding for the needle&#39;s winding action, which enables the winding to smoothly slide down to form the coil  46  on the magnetic pole tooth  51  while keeping the height of the circumference changing member  101  constant. 
   However the upper surface of the circumference changing member  101  may be inclined downwardly toward the bottom side as with the before-mentioned taper members  65 . Forming such an inclined surface also enables the winding to slide down to the bottom side as described before. However, forming such an inclined surface makes the height of the circumference changing member on the inlet side of the slot greater, resulting in a large protrusion of the coil ends, and therefore, a greater profile thereof in the radial direction, as aforenoted. With respect to this, keeping the height constant as in the example shown in  FIGS. 29–35  enables to obtain a stator with a compact profile. 
   Although not necessary, a projection  103  may be formed either on the bobbin  57  at the base of the circumference changing member  101  or on the circumference changing member  101  itself. 
   Thus, from the foregoing description, it should be readily apparent that the described structures and winding methods provide very dense coil windings and afford very rapid winding methods at a relatively low cost as compared to the prior art constructions and methods. Of course, the foregoing description is that of preferred embodiments of the invention and various changes and modifications in addition to those mentioned may be made without departing from the spirit and scope of the invention, as defined by the appended claims.