Abstract:
An apparatus for winding stator teeth includes at least one fly winder for winding wire around stator teeth. At least one stator teeth holder includes stator tooth retainers at spaced locations for retaining stator teeth thereon. The at least one stator tooth holder and fly winder are moveable relative to one another to present each stator tooth to the at least one fly winder for winding a wire coil thereon. The stator tooth retainers are relatively positioned on the at least one stator teeth holder to control a span of wire extending between the stator teeth after the stator teeth have been presented to the at least one fly winder and wound.

Description:
REFERENCE TO CROSS-RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application No. 60/484,649 filed on Jul. 7, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to electric machinery and in particular to an apparatus and method for winding stator teeth.  
       BACKGROUND OF THE INVENTION  
       [0003]     Electric machinery that includes stators accommodating rotors, such as for example electric motors and generators, is well known in the art. Stators of such electric machinery typically include a series of connected electrical wire coils formed on stator teeth mounted around the internal periphery of a ring. The electrical wire coils are wound in alternating orientations on the stator teeth, creating a set of alternating magnetic fields about the internal periphery of the ring when energized by a current.  
         [0004]     In the case of electric generators, the rotor, which carries magnets of alternating polarity about its circumference, is rotated within the stator to generate current in the coils as the magnets align with coils. The strength of the current is dependent on the strength of the magnets, the speed at which the rotor rotates, and the number of loops in each coil.  
         [0005]     Conversely, in the case of electric motors, an alternating current is run through the coils, creating a combination of magnetic attraction and repulsion forces that rotate the magnet-carrying rotor.  
         [0006]     It has been found that close relational placement of the stator teeth supporting the coils leads to more efficient power conversion of the stator. As the stator teeth reside on the inside periphery of the ring, access thereto is restricted. Further, when the stator teeth are placed close to one another, little working space is provided to wind the wire around the individual stator teeth to form coils thereon. As a result, a number of methods for winding wire around the stator teeth prior to their final positioning in the stator have been considered.  
         [0007]     For example, U.S. Pat. Nos. 6,121,711 and 6,323,571 to Nakahara et al. disclose a method of manufacturing a stator for magnetic disk drive units. The stator includes a stator body comprising two or more segments that are hingedly connected, allowing the segments to be positioned into either a generally linear arrangement or a generally circular arrangement. Each segment has one or more stator teeth on a side thereof. Wire is coiled about the stator teeth when the segments are generally linearly arranged and the wire ends are connected to terminations. The segments are then formed into an annulus and secured. Unfortunately, a number of problems exist with this stator teeth winding approach. In situations where each segment has more than one stator tooth, the relative proximity of the stator teeth is limited by the space required to accommodate the winding mechanism used to wind the wire around each stator tooth. In situations where each segment only has one stator tooth, while the winding of wire around each stator tooth is facilitated by swinging adjacent segments away from the segment having the stator tooth being wound, the increased number of hinge connections between segments increases the cost and complexity of the stator.  
         [0008]     U.S. Published Patent Application No. 2002/0011755 to Shteynberg et al. discloses a method of winding stator teeth that are stacked side-by-side to form a column, with a spacer placed between each adjacent pair of stator teeth, leaving exposed the peripheral edges of the stator teeth about which wire is wound. The column of stator teeth is clamped on opposing ends and mounted onto a rotating platform adjacent a wire dispenser. As the column of stator teeth is rotated, the wire dispenser winds wire around each stator tooth, one after another, until all of the stator teeth have coils formed thereon. As the wire dispenser moves from stator tooth to stator tooth, a span of wire is extended between them. Posts are then inserted into preformed bores around the perimeter of the spacers around which the wire dispenser routes the span of wire. The posts are positioned such that the length of the span of wire extending between two adjacent stator teeth is controlled to some extent. In an alternative embodiment, opposing stator teeth surfaces are equipped with mating features to allow the column of stator teeth to be securely clamped at its two opposing ends without spacers. In a further embodiment, a first set of stator teeth is mounted on a first ring with spaces between the stator teeth equal to the width of a stator tooth. Coils are wound on the stator teeth mounted on the first ring in a first orientation (that is, either clockwise or counter-clockwise). Likewise, a second set of stator teeth is mounted on a second ring that is complementary to the first ring, with spaces between the stator teeth equal to the width of a stator tooth. Coils are then wound on the stator teeth mounted on the second ring in an orientation opposite to the first orientation. The rings are then coupled, interleaving the stator teeth to form a stator having adjacent stator teeth carrying coils wound in opposite orientations.  
         [0009]     While the Shteynberg et al. stator teeth winding methods address some of the problems associated with conventional stator teeth winding methods, a number of problems still exist with the Shteynberg et al. stator teeth winding methods. For example, forming the column of stator teeth and spacers prior to winding is time-consuming and complicated. Further, the method for controlling the span of wire between the stator teeth is complicated and produces a set number of discrete span lengths, thus limiting the number of stator configurations that can be produced.  
         [0010]     As will be appreciated, an improved stator teeth winding methodology that overcomes the above disadvantages is desired. It is therefore an object of the present invention to provide a novel apparatus and method for winding stator teeth.  
       SUMMARY OF THE INVENTION  
       [0011]     Accordingly, in one aspect of the present invention, there is provided an apparatus for winding stator teeth, comprising: 
        at least one fly winder for winding wire around stator teeth; and     at least one stator teeth holder including stator tooth retainers at spaced locations for retaining stator teeth thereon, said at least one stator tooth holder and fly winder being moveable relative to one another to present each stator tooth to said at least one fly winder for winding a wire coil thereon, wherein said stator tooth retainers are relatively positioned on said at least one stator teeth holder to control a span of wire extending between said stator teeth after said stator teeth have been presented to said at least one fly winder and wound.        
 
         [0014]     In one embodiment, the stator teeth holder is rotatable to present each stator tooth to the fly winder. The stator tooth retainers are circumferentially spaced about the stator teeth holder and are vertically offset with respect to one another. The stator teeth holder is also vertically adjustable to present each stator tooth to the fly winder. In the case where the stator teeth holder includes a pair of stator tooth retainers each for retaining a single stator tooth, the fly winder winds each stator tooth in a manner so that the coils on the stator teeth have opposite orientations.  
         [0015]     Each stator tooth retainer includes a channel shaped to accommodate a stator tooth. The channel is defined by a clamp assembly accommodated by the stator teeth holder. The clamp assembly includes a pair of side clamps for engaging opposite sides of a stator tooth. The clamp assembly may further include a biasing member actuable between engaged and disengaged states. In the engaged state, the biasing member biases the stator tooth into engagement with the side clamps. Alternatively, the channel may be sized to form a friction fit with the stator tooth.  
         [0016]     The stator teeth holder may include a main body including a pair of cutouts formed therein with each of the cutouts accommodating a respective clamp assembly. The main body presents a generally arcuate outer surface bridging the cutouts.  
         [0017]     According to another aspect of the present invention, there is provided an apparatus for winding stator teeth, comprising: 
        a fly winder for winding wire around stator teeth; and     a stator teeth holder including a rotatable turret having a main body and stator tooth retainers at spaced locations on said main body for retaining stator teeth, said turret being rotatable to present each stator tooth to said fly winder for winding a wire coil thereon, wherein said stator tooth retainers are relatively positioned on said turret in a manner such that after said stator teeth have been wound by said fly winder to include coils of opposite orientation, removed from said turret and placed side-by-side, the span of wire extending between said stator teeth includes substantially no excess length.        
 
         [0020]     According to yet another aspect of the present invention there is provided a method of winding stator teeth, comprising: 
        mounting a first stator tooth and a second stator tooth at spaced locations on a tool;     presenting said first stator tooth to a winding device and winding a coil having a first orientation thereon;     biasing said tool to present said second stator tooth to said winding device; and     winding a coil on said second stator tooth having an orientation opposite that of the coil wound on said first stator tooth, wherein the relative locations of said first stator tooth and said second stator tooth on said tool are such that the span of wire extending from said first stator tooth to said second stator tooth includes substantially no excess length when said first stator tooth and second stator tooth are positioned side-by-side.        
 
         [0025]     The present invention provides advantages in that since the length of the span of wire between two stator teeth is controlled during winding, the stator teeth can be positioned in a stator side-by-side with substantially no excess wire extending therebetween. Also, by vertically offsetting the stator teeth relative to one another during winding, the stator teeth can be positioned further apart, thus facilitating winding, and allowing the length of wire extending between the stator teeth to be more easily controlled. Further, the present invention allows for stator teeth to be wound in alternating orientations while retaining control over the span of wire extending between pairs of stator teeth.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]     An embodiment of the present invention will now be described, more fully with reference to the accompanying drawings in which:  
         [0027]      FIG. 1  is a side elevation view of an apparatus for winding stator teeth in accordance with the present invention;  
         [0028]      FIG. 2  is a perspective view of a portion of the apparatus of  FIG. 1 ;  
         [0029]      FIG. 3  is a perspective view of a sub assembly forming part of a stator teeth holding tool;  
         [0030]      FIG. 4  is a perspective view of a turret forming part of the stator teeth holding tool;  
         [0031]      FIG. 5  is a top plan view of the turret;  
         [0032]      FIG. 6  shows two stator teeth in their relative positions when mounted on the turret; and  
         [0033]      FIG. 7  shows the two stator teeth of  FIG. 6  when removed from the turret and positioned side-by-side. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]     Turning now to FIGS.  1  to  3 , an apparatus for winding stator teeth in accordance with the present invention is shown and is generally identified by reference numeral  10 . Apparatus  10  includes a plurality of fly winders  12  and a stator teeth holding tool  14 . For ease of illustration only one fly winder  12  is shown. Also, since fly winders are well known in the art, for ease of illustration, some of the components of the fly winder have been omitted from the figures. Each fly winder  12  includes a flyer head  24  having a flyer arm  28  and a counterweight  32  joined by a central body section  34 . A nozzle  36  is positioned at the distal end of the flyer arm  28  and is operable to dispense wire to be wound around stator teeth when flyer head  24  is rotated about a central horizontal axis. A pair of redirector pulleys  40  and  44  allow wire to be routed to nozzle  36 . Pulley  40  is positioned within a channel  46  provided in the flyer arm  28 , adjacent the nozzle  36 , and pulley  44  is positioned on the central body section  34 . Flyer head  24  is mounted on a rotating hollow shaft (not shown), providing flyer head  24  with rotational movement in both directions about an axis coaxial with opening  48  in the central body section  34 . Further, the fly winder  12  is operable to move flyer head  24  along the two axes of a horizontal plane. Wire to be dispensed by the fly winder  12  passes over redirector pulley  44 , through channel  46  in the flyer arm  28 , over redirector pulley  40  and through nozzle  36 .  
         [0035]     The stator teeth holding tool  14  presents stator teeth to the fly winders  12  to enable the fly winders  12  to wind coils thereon. As shown in  FIG. 3 , stator teeth holding tool  14  includes a sub assembly  50  supporting a plurality of posts  52 . Sub assembly  50  includes a pair of motors  54  and a motor  56 . Each motor  54  is associated with a pair of posts  52  and is coupled to the pair of posts by a transmission. In this manner, each motor  54  is operable to rotate each post  52  in its associated pair about the central longitudinal axis of each post  52 . Motor  56  is operable to raise and lower the posts  52 .  
         [0036]     A fixturing detail  60  is disposed on the top of each post  52 . A turret  62  is slidably received by and rests on each post  52 . Only one turret  62  is shown in the figures for ease of illustration. In this embodiment, turret  62  includes a pair of pegs  64  around which wire is turned in preparation for termination. A stationary tie-off post  66  is positioned on the sub assembly  50  adjacent each post  52 . Each turret  62  is associated with one of the fly winders  12 . In conjunction with the two degrees of movement of turret  62  by virtue of the movement of the posts  52 , flyer head  24  of its associated fly winder  12  has five degrees of movement relative to the turret  62 .  
         [0037]      FIGS. 4 and 5  better illustrate one of the turrets  62 . As can be seen, the turret  62  includes a main body  70  that is generally cylindrical in shape when viewed in top plan. A pair of clamp assemblies  72  are accommodated by cutouts  74  provided in the main body  70  to receive and retain a pair of stator teeth  100   a  and  100   b  to be wound. The cutouts  74  are positioned 90 degrees apart relative to the outer peripheral surface  76  of the turret  62  and are vertically offset. The outer peripheral surface  76  of the turret  62  bridging the cutouts  74  is arcuate.  
         [0038]     Each clamp assembly  72  includes a back plate  80  and a pair of side clamps  82  that define a dove-tailed channel  84  accessible from the top and bottom. The side clamps  82  are designed to engage a stator tooth  100  to be wound that is inserted into the dove-tailed channel  84 . In order to enable the side clamps  82  to engage the stator tooth, the back plate  80  accommodates a cam-shaped member (not shown). The cam-shaped member is actuable between an engaged state wherein the stator tooth  100  is engaged by the side clamps  82  and retained by the clamp assembly  72  and a disengaged state wherein the stator tooth is moveable along the dove-tailed channel  84 . In the engaged state, the cam-shaped member projects outwardly from the back plate  80  to contact and bias the stator tooth  100  into engagement with the side clamps  82  thereby to retain the stator tooth.  
         [0039]     Since the turret  62  is designed to support only two stator teeth  100 , the main body  70  of the turret only includes structure to engage stator teeth at the desired positions thereby to reduce the weight of the turret. By reducing the weight of turret  62 , less stress is placed on automation machinery that is used to mount and dismount turrets  62  on the posts  52 .  
         [0040]     Each stator tooth  100  includes an outer arc plate  102 , an inner arc plate  104  and a winding core  106  between the plates  102  and  104  about which wire is to be wound. The outer arc plate  102  is shaped generally complimentary to the dove-tailed channel  84  to facilitate insertion of the outer arc plate therein.  
         [0041]     During operation, two stator teeth  100   a  and  100   b  that have not yet been wound with coils are loaded onto each turret  62  by sliding them into the dove-tailed channels  84  of the clamp assemblies  72  before each turret  62  is secured to a respective post  52 . The cam-shaped members within back plates  80  are then actuated to engage and bias stator teeth  100   a  and  100   b  firmly against side clamps  72 . The turrets  62  are then mounted onto the fixturing details  60  disposed on the posts  52  and preferably locked in place to avoid vertical movement of the turrets  62  during winding. In this condition for each turret  62 , one stator tooth  100   a  is positioned towards a lower end of the turret  62 , whereas the other stator tooth  100   b  is positioned towards an upper end of the turret  62 , and spaced 90 degrees about the circumference of the turret  62 . As the stator teeth  100   a  and  100   b  are mounted on perpendicular surfaces of each turret  62 , a wire spanning the two stator teeth must undergo a 90 degree change of direction. The arcuate outer peripheral surface  76  of the main body  70  spanning the cutouts allows a span of wire to be gradually routed from the top of one of stator tooth to the bottom of the other stator tooth, thus avoiding unnecessary sharp bends in the wire, which can damage the wire enamel and cause downstream rejects in the electric machinery in which the stator teeth  100   a  and  100   b  are utilized.  
         [0042]     Each post  52  and associated turret  62  are then lowered to present one of the pegs  64  to the flyer head  24  of its associated fly winder  12 . For each turret and fly winder pair, a wire extending from stationary tie-off post  66  to the nozzle  36  of the flyer head  24  is turned around the presented peg  64  by moving the flyer head  24  along the two horizontal axes of movement. The wire protruding from the nozzle  36 , which was terminated to the stationary tie-off post  66  or clamped at the end of the last wind cycle, is thus wound around peg  64  under tension. Next, the post  52  and turret  62  is rotated and raised to present a first stator tooth  100   a  to the flyer head  24  for winding. It is preferable to position stator tooth  100   a  in the axis of rotation of the flyer head  24  so that the wire is distributed evenly about stator tooth and is generally evenly tensioned thereabout. Flyer head  24  is then positioned in front of stator tooth  100   a  and a pre-set number of loops of wire are coiled around stator tooth in a counter-clockwise direction, with the flyer  24  head moving incrementally further from turret  62  with each loop of wire thereby to evenly distribute the wire about winding core  106 . Once a first set of loops has been wound around the winding core  106 , flyer head  24  moves slowly toward turret  62  all while flyer head  24  continues to rotate about the stator tooth  100   a  to wind a second set of loops of wire about winding core  106 .  
         [0043]     Once the second set of loops is complete, turret  62  is rotated and lowered to present the second stator tooth  100   b  to flyer head  24  for winding. As this is done, a span of wire  110  is extended from the top of the first stator tooth  100   a  to the bottom of the second stator tooth  100   b . At this point, flyer head  24  is operated in a clockwise direction to wind a first set of loops of wire around stator tooth  100   b , all while flyer head  24  moves incrementally away from turret  62  with each loop. Once the first set of loops is complete, flyer head  24  begins to move slowly toward turret  62  to distribute a second set of loops of wire evenly around winding core  106 .  
         [0044]     Upon completion of the second set of loops, turret  62  is lowered and flyer head  24  is moved through the two horizontal axes to form a set of turns about a second of the pegs  64 . Upon completion of the set of turns, flyer head  24  moves to wind a set of loops of wire around the stationary tie-off post  66 . The wire is then cut between the pegs  64  and the stationary tie-off post  66 .  
         [0045]     At this point, turret  62  having two wound stator teeth is removed from post  52  by unsecuring it and lifting it, making room for another turret  62  bearing a set of stator teeth to be wound. Completed stator teeth are then removed from turret  62  by actuating the cam-shaped members to allow the completed stator teeth to slide out of the dove-tailed channels  84 .  
         [0046]      FIG. 6  shows a pair of stator teeth  100   a  and  100   b  having coils  108  formed thereon and joined by the span of wire  110 . A terminating wire end  112  extends from each stator tooth for connection in a stator. Arrows  114  depict the direction in which stator teeth are moved to arrive at their final relative position side-by-side, as shown in  FIG. 7 , wherein span of wire  110  is taut and includes substantially no excess length. As will be appreciated, in this final position, adjacent stator teeth have coils of opposite orientation; that is, one is wound clockwise and another is wound counter-clockwise.  
         [0047]     While the present invention has been described with specificity to mounting stator teeth onto a turret that presents the stator teeth to the fly winder for winding, other types of stator teeth supports will occur to those of ordinary skill in the art. For example, a plate having a number of positions for securing stator teeth in a similar fashion as employed in the described embodiment can be used. The plate can be raised and lowered relative to the fly winder just as the turret, and can be moved relative to the fly winder along a longitudinal axis to present a different stator tooth to the flyer head, simulating the rotation of the turret.  
         [0048]     The positions of the stator teeth on the turret can be made adjustable to allow different dimensioned stator teeth to be coiled using the same turret. Further, the turret can be made expandable, through additional concentric surface layers on its periphery, through the placement of each stator tooth on a separate arcuate plate whose distance from the center of the turret can be adjustable, or through some other means.  
         [0049]     Although the stator teeth are shown as being positioned ninety degrees apart about the circumference of the turret, it is to be appreciated that the stator teeth can be positioned in other configurations. For instance, the stator teeth can be placed along the circumference of the turret at varying degrees, depending on the circumference of the turret, the relative vertical separation of the stator teeth positions along the vertical length of the turret, and any variation in the radial distance of the stator teeth positions along the surface of the turret.  
         [0050]     While specific reference is made to the posts upon which the turrets are mounted being controlled by a set of motors, other methods of controlling the posts will occur to those skilled in the art. For example, pneumatic or hydraulic means can be alternatively employed to control movement of the posts.  
         [0051]     The turrets can be equipped with clamps in place of pegs to engage the wire ends during the start and end of the winding process. This method of termination is well-suited to work with both a wire which has been previously terminated on a stationary tie-off post, and one which is loosely hanging out of the flyer nozzle, and is especially beneficial for use with heavier gauge wires.  
         [0052]     Although the clamp assemblies are described as including cam-shaped members to bias the stator teeth into engagement with the side clamps, other means of securing the stator teeth to the turrets during the winding process can be used. For example, the stator teeth can be frictionally fit into the dove-tailed channels.  
         [0053]     Also, although the apparatus is described as including a fly winder associated with each turret, fewer fly winders that are moveable laterally between multiple turret locations can be used.  
         [0054]     Although embodiments of the present invention have been described, those of skill in the art will appreciate that the variations and modifications may be made without departing from the spirit and scope thereof as defined by the appended claims.