Abstract:
In certain embodiments, an electromechanical device is provided with N sets of stator segments, each segment comprising a respective, separate bobbin, the N sets of segments being wound with a single continuous length of wire for each set such that the segments of each set are electrically in series. The electromechanical device, in certain embodiments, has the N sets of segments combined in a common circumferentially adjacent circular arrangement, wherein the single continuous length of wire of each segment is maintained on the bobbin on which the wire was wound.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a divisional of application Ser. No. 09/407,136 filed on Sep. 27, 1999 now U.S. Pat. No. 6,941,644. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a method and apparatus for winding a segmented stator or rotor of an electromechanical device, such as an electric motor or generator. In a particularly preferred embodiment, the invention relates to a method and apparatus for winding a segmented stator or rotor in which multiple segments for one phase are wound as a set, and then combined with other sets of wound segments for the remaining phases of the motor or generator. 
   2. Description of Related Art 
   Electromechanical devices such as motors and generators comprise a stator and a rotor that rotates relative to the stator. In all such devices, either the stator or the rotor (or both) comprises windings that determine basic characteristics of the device. 
   Focusing for example on a stator of an electric motor, the stator is provided with a number of windings that is determined by the number of phases of the motor. For example, a three phase motor has a stator with three windings. Each of the windings further comprises 2N poles per winding, where N is an integer equal to or greater than one. For example, a three phase four pole motor comprises a total of twelve poles. Each pole further includes one or more coils, with each coil being formed of numerous turns of wire wound around a common bobbin structure. 
   Various techniques are known for constructing a stator of an electric motor. For example, according to one known technique, the stator is constructed using a large number of very thin laminations that, when stacked together, produce a stator structure that is generally cylindrically shaped with but with bobbin structures that extend the length of the cylinder and that protrude radially inwardly. The bobbins are then each wound with wire to form respective stator coils using a needle-based winding machine that is placed at the center of the stator structure. 
   A recognized problem with this approach is that the amount of wire that can be provided on each bobbin is limited by the fact a certain amount of space is required for the operation of the winding machine. During the winding operation, the needle travels in the slots that are between the bobbins and, as wire fills the slots, the amount of space left for the needle to travel decreases. The winding operation ends when there is not enough room left in the slots for the needle to travel. At this time, however, the slots are not completely filled with wire, resulting in unutilized space (i.e., incomplete slot fill) once the winding operation is complete. In general, it is desirable to have as many turns of wire as possible in the space provided (i.e., maximum slot fill) in order to maximize the torque and speed characteristics of the motor. 
   A recognized solution to this problem is to utilize what is referred to in the art as a segmented stator. According to this approach, the stator is constructed using a plurality of segments each of which defines a bobbin upon which wire is wound to form one of the coils of the motor. Each segment is generally T-shaped when viewed from one end of the motor, with the bottom (vertical) leg of the T forming the bobbin upon which wire is wound to form one of the coils of the motor, and the top (horizontal) leg of the T being joined end to end with the top legs of the other T-shaped segments in the shape of a circle, thereby resulting in a circular stator when viewed from one end of the motor. This construction technique therefore results in a stator with an overall shape that is the same as that of an unsegmented stator. 
   The use of a segmented stator allows for complete slot fill because each segment can be wound individually before being physically combined with the remaining stator segments. As a result, there are no space restrictions to interfere with the operation of the winding machine and to thereby prevent each segment from being completely wound. 
   However, the fact that the segments are wound individually also requires an increased number of connections that must be made using manual techniques, thereby leading to increased human error in the construction process. Because the segments are wound individually, the various coils must be connected once the stator segments are combined. The coils are not simply all connected in series or parallel but rather are connected according to intricate connection patterns. For example, for a three phase motor, the coils for each phase are connected in series in alternating fashion around the motor, and the windings that are thereby formed are then connected in either a wye or a delta configuration. Even the most careful individuals are prone to making mistakes when trying to connect the various coils in the correct manner. Of course, connecting the coils in an incorrect manner results in a defective motor. 
   Thus, a system and method of constructing a wound member of an electromechanical device that utilizes a segmented construction technique, but that also avoids the need for the increased number of manual connections that are required by the segmented construction techniques described above, would be highly advantageous. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention overcomes these drawbacks of the prior art. According to a first aspect of the invention, the invention provides a method of constructing a segmented wound member of an N phase electromechanical device, comprising winding N sets of segments and combining the N sets of segments in a common circular arrangement to form the wound member. The N sets of segments are wound with a single continuous length of wire for each set. Each of the N sets of segments is wound separately from the remaining sets of segments and then combined in the common circular arrangement with the remaining sets of segments to form the wound member. 
   In a first preferred implementation, the winding step includes the following steps. First, a plurality of segments are arranged in a side-by-side orientation along an axis of rotation. The plurality of segments form one of the previously-mentioned N sets of segments. The plurality of segments and a wire dispenser are then rotated relative to each other about the axis of rotation. The plurality of segments are wound during the relative rotation of the plurality of segments and the wire dispenser. The arranging, rotating and winding steps are repeated for each of the remaining sets of segments. 
   In a second preferred implementation, the winding step includes the following steps. First, a plurality of segments are arranged in a circular arrangement with spaces therebetween. Again, the plurality of segments form one of the previously-mentioned N sets of segments. Then, the plurality of segments are wound, and the arranging and winding steps are repeated for each of the remaining sets of segments. 
   According to another aspect of the invention, a winding fixture for winding segments of a segmented wound member of an electromechanical device comprises a motor, a rotatable clamp, and a wire dispenser. The rotatable clamp is mechanically coupled to the motor and is capable of being driven by the motor to rotate about an axis of rotation during a winding operation. The rotatable clamp includes first and second end sections that are spaced from each other along the axis of rotation. The first and second end sections are capable of clamping together a plurality of segments in a manner such that the plurality of segments are arranged in a side-by-side orientation along the axis of rotation and such that the plurality of segments rotate about the axis of rotation during the winding operation. 
   The wire dispenser is movable in a direction parallel to the axis of rotation to various positions adjacent the plurality of segments. The wire dispenser is capable of dispensing wire to each of the plurality of segments by moving from position to position and dispensing wire as the rotatable clamp and the plurality of segments rotate during the winding operation. 
   Advantageously, the preferred winding fixtures are constructed and arranged so as to permit segments to be wound as a set with a single continuous length of wire. For example, one set may be used for each phase of the electromechanical device. As a result, when the various sets of stator segments are combined, the number of manual interconnections that must be made is minimized. In the context of a three phase motor, for example, all that is required is to connect the three sets of segments in a wye or delta configuration, and it is not necessary to first connect each of the segments within each phase. 
   Additionally, the preferred winding fixtures achieve this advantage while making maximum use of existing bobbin winding technologies. The bobbin winders utilized by the preferred winding fixtures may be similar for example to bobbin winders that have previously been used for individually winding segments with separate lengths of wire, or to those that have been previously been used for winding unsegmented stators. As a result, the winding fixture  10  can be implemented in straightforward fashion by making maximum use of existing technologies. 
   Other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many modifications and changes within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred exemplary embodiment of the invention is illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
       FIG. 1  is a perspective view of a winding fixture according to a first preferred embodiment of the present invention; 
       FIG. 2  is a more detailed perspective view showing the operation of the winding fixture of  FIG. 1 ; 
       FIG. 3  is a perspective view showing stator segments wound using the winding fixture of  FIG. 1 ; 
       FIG. 4  is an exploded perspective view showing stator segments wound using the winding fixture of  FIG. 1 ; 
       FIG. 5  is a perspective view of the wound stator segments of  FIGS. 3-4  arranged in a circular arrangement to form part of a stator; 
       FIG. 6  is a schematic view of a completed stator assembly constructed in accordance with the first preferred embodiment of the invention; 
       FIG. 7  is a perspective view that corresponds to  FIG. 4  but showing an alternative embodiment that uses dimpled segments instead of nests; 
       FIG. 8  is a perspective view of a winding fixture according to a second preferred embodiment of the invention; 
       FIG. 9  is a perspective view of a plurality of segments separated by spacers and clamped within a ring clamp; 
       FIG. 10  is a plan view of the assembly of  FIG. 9 ; 
       FIG. 11  is a perspective view of an assembly fixture used in connection with the assembly of  FIGS. 9-10 ; 
       FIG. 12  is a perspective view of the clamped assembly of  FIG. 9-10  mounted on the assembly fixture of  FIG. 11 ; 
       FIG. 13  is a perspective view of the assembly fixture of  FIG. 11  with the stator segments of  FIG. 9  mounted thereon, and receiving a second set of segments; and 
       FIG. 14  is a perspective view of a completed stator assembly constructed in accordance with the second preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIG. 1 ,  FIG. 1  shows a perspective view of a winding fixture  10  according to a first embodiment of the invention. The winding fixture  10  is used to wind a plurality of segments  15  of a segmented wound member of an electromechanical device, such as the stator or rotor of a motor or generator. Herein, it will be assumed that the segments are stator segments for an electric motor, and in particular for a three phase four pole motor. 
   In  FIG. 1 , the plurality of segments  15  includes four individual segments  15   a ,  15   b ,  15   c  and  15   d . The segments  15  are wound as a set using the winding fixture  10 . As described in greater detail below, two additional sets of segments are then also separately wound in the same manner, and the three sets of segments are combined in a common circular arrangement to form the stator for the three phase four pole motor, with each one of the three phases being formed by one of the three sets of wound segments. 
   The winding fixture  10  comprises a motor  18 , a rotatable clamp  20  that is coupled to the motor  18 , and a bobbin winder  30 . Only a portion of the motor  18  is shown in  FIG. 1 , which may in practice be part of a gear or pulley system that couples a motor shaft (not shown) of the motor to a rotatable input shaft  21  of the rotatable clamp  20 . 
   The rotatable clamp  20  further comprises first and second outer end sections  22   a  and  22   e  that clamp together the segments  15 . The first and second outer end sections  22   a  and  22   e  form nests that are similar to several additional nests  22   b ,  22   c , and  22   d  which are disposed in alternating fashion between the segments  15 . The segments  15  and the nests  22  are arranged in a side-by-side orientation along an axis of rotation which, in  FIG. 1 , is shown to be the X-axis and is defined by the axis of rotation of the shaft  21 . 
   Compressive force is applied to the nest  22   e  by the shaft  26 , which has a position along the axis of rotation that is adjustable by a course adjustment mechanism  26  and a tightening assembly  28 . The position of the nest  22   e  along the axis of rotation depends on the number and thickness of the segments to be wound. 
   The bobbin winder  30  is disposed adjacent the segments  15  and the nests  22 . The bobbin winder  30  is conventional and may, for example, be a model ER 500 CNC2 or ER26L CNC winder (available from Bobifil, Poligono Industrial Virgen de la Salud, 46950 Chirivella (Valencia) Spain) however, any suitable bobbin winder may be used. The bobbin winder  30  includes an assembly  32  that is moveable back and forth along two posts  34  that are parallel to the axis of rotation. Movement of the assembly  32  is controlled by a lead screw assembly  36  which is driven by an additional motor (not shown). The assembly  32  also includes a wire dispenser  38  (shown more clearly in  FIG. 2 ) which moves back and forth in the X-direction to various positions adjacent the segments  15  as the assembly  34  moves along the posts  36 . The assembly  32  could also be movable in other directions in addition to the X direction, for example, in both the X direction and the Y direction (e.g., in an arc), however, this arrangement is not preferred. 
   Referring now also to  FIG. 2 , the operation of the winding fixture  10  is described in greater detail. In operation, the segments  15  and the wire dispenser  38  rotate relative to each other while the wire dispenser  38  sequentially dispenses wire onto each one of the segments  15 , until all of the segments  15  have been wound. In particular, the rotatable clamp  20  is driven by the motor  18  and rotates about the axis of rotation defined by the shaft  24 , thereby causing the segments  15  to rotate about the same axis. Although it would also be possible to have the segments  15  and the wire dispenser  38  rotate relative to each other by having the plurality of segments  15  remain stationary while having the wire dispenser  38  rotate, rotation of the segments  15  is preferred. 
   As the segments  15  rotate, the wire dispenser  38  moves in a direction parallel to the axis of rotation to various positions that are each adjacent a respective one of the segments  15 . At each position, the wire dispenser  38  remains substantially stationary while dispensing wire to the respective one of the segments  15  as the segments  15  rotate. In practice, a small amount of movement at each position may be necessary for proper wire placement. As the wire dispenser  38  moves between segments  15 , posts  27  on the nests  22  are preferably used to control the amount of wire that is placed between each separate segment  15 . This amount of wire is required to permit the segments  15  to be spaced from each other in the completed stator (see  FIGS. 5-6 ). 
   This process continues for each of the segments  15 , until all of the segments  15  have been wound. It is therefore seen that, because the segments  15  are wound in a single winding operation, it is possible to wind the segments  15  with a single continuous length of wire. Although it would also be possible to use the winding fixture  10  for winding individual segments with separate lengths of wire by starting a new length of wire for each segment  15 , this approach is not preferred. 
     FIGS. 3 and 4  show the segments  15  after the winding operation shown in  FIG. 2  is complete. Additionally,  FIG. 3  shows alternative nests  22 ′ in which the posts  27  are not used to control the amount of wire that is disposed between each separate segment  15 . In the embodiment of  FIG. 3 , this control is achieved manually.  FIG. 4  is similar to  FIG. 3 , except that it shows an exploded view of the segments  15  and the nests  22 ′. As illustrated in  FIG. 4 , the segments  15  may include mounting ends  18  through which the segments  15  may interface with the nests  22 ′. 
     FIG. 5  shows the stator segments  15  placed into a circular arrangement to partially form a stator. For a three phase motor, the process that has been described with respect to  FIG. 2  is performed two additional times for a total of three times, one time for each phase of the motor. In general, for an N phase M pole motor, N sets of M segments are utilized, assuming each pole is implemented with a single coil. Of course, it is also possible to implement each pole using multiple coils. In the illustrated embodiment N is equal to 3 and M is equal to 4.  FIG. 6  schematically shows the segments  15  combined in a common circular arrangement with two additional sets of segments  16  and  17  to form a completed three phase stator. 
     FIG. 7  shows an alternative embodiment in which segments  15 ′ are each provided with dimples that are engaged by protrusions on adjacent segments  15 ′. As well, the inner surface of each segment  15 ′ is adapted to engage the outer surface of the adjacent segment  15 ′. This arrangement allows the segments to be clamped between end sections  22   a ′ and  22   e ′ without the use of nests. 
   From the foregoing description, a number of advantages of a winding fixture according to a first embodiment of the invention are apparent. First, the winding fixture  10  is constructed and arranged so as to permit segments to be wound as a set with a single continuous length of wire. For example, one set may be used for each phase of the electromechanical device. As a result, when the various sets of stator segments are combined, the number of manual interconnections that must be made is minimized. In the context of a three phase motor, for example, all that is required is to connect the three sets of segments in a wye or delta configuration, and it is not necessary to first connect each of the segments within each phase. 
   Additionally, the winding fixture  10  achieves this advantage while making maximum use of existing bobbin winding technologies. The bobbin winder  32  may be similar for example to bobbin winders that have previously been used for individually winding segments with separate lengths of wire. As a result, the winding fixture  10  can be implemented in straightforward fashion by making maximum use of existing technologies. 
   Referring now to  FIG. 8 , a perspective view of a winding fixture  110  according to a second embodiment of the invention is illustrated. The winding fixture  110  is used to wind a plurality of segments  115  of a segmented wound member of an electromechanical device. Again, for purposes of explanation, the segments  115  to be stator segments of a three phase four pole electric motor. 
   Like the segments  15  of  FIG. 1 , the plurality of segments  115  in  FIG. 8  includes four individual segments  115   a ,  115   b ,  115   c  and  115   d . The segments  115  are wound as a set using the winding fixture  110 . As described in greater detail below, two additional sets of segments are then also separately wound in the same manner, and the three sets of segments are combined in a common circular arrangement to form the stator for the three phase four pole motor, with each one of the three phases being formed by one of the three sets of wound segments. 
   The winding fixture  110  comprises a ring clamp  120  and a bobbin winder  130 . The segments  115  are disposed inside the ring clamp  120  in a circular arrangement with a plurality of spaces between respective ones of the segments  115 . The ring clamp  120  clamps the segments  115  in place and to this end includes a plurality of spacers  122  that are disposed in the spaces between the segments  115  and that maintain the spacing between the segments  115 . 
   The ring clamp is sized so as to match the size of the stator that is being constructed. With four poles per phase, the segments are disposed at 90° intervals in the ring clamp  120 . Additionally, with a total of twelve segments, each segment occupies a 30° arc in the circle defined by the ring clamp  120 , with the spacers  122  occupying the remaining 60° between each segment. 
   The bobbin winder  130  is disposed so as to be substantially at the center of the segments  115 . The bobbin winder  30  is conventional and may, for example, be a model XL6 2 single spindle winder (available from Windamatic Systems, Inc., Box 10071, Fort Wayne, Ind. 46850) however, any suitable bobbin winder may be used. The bobbin winder  130  includes an assembly  132  that rotates about an axis of rotation that passes through the center of the ring clamp  120 . The assembly  132  also includes a wire dispenser  138  which moves in a circle to various positions adjacent the segments  115  as the assembly  34  rotates. The segments  115 , the ring clamp  120 , and the path of motion of the wire dispenser  138  are therefore concentrically arranged about the axis of rotation. The assembly  132  could also have more complex motion capabilities, however, this arrangement is not preferred. 
   In operation, the segments  115  and the wire dispenser  138  rotate relative to each other while the wire dispenser  138  sequentially dispenses wire onto each one of the segments  115 , until all of the segments  115  have been wound. In particular, the wire dispenser  138  rotates within the ring clamp  120  and rotates about the axis of rotation which passes through the center of the ring clamp  120 . Although it would also be possible to have the segments  115  and the wire dispenser  138  rotate relative to each other by having the plurality of segments  115  rotate while having the wire dispenser  138  remain stationary, rotation of the wire dispenser  138  is preferred for reasons described below. 
   As the wire dispenser  138  rotates, it moves to various positions that are each adjacent a respective one of the segments  115 . At each position, the wire dispenser  138  remains substantially stationary while dispensing wire to the respective one of the segments  115 . In practice, a small amount of movement of the wire dispenser  138  at each position may be necessary for proper wire placement. 
   This process continues for each of the segments  115 , until all of the segments  115  have been wound. Advantageously, because the segments  115  are wound in a single winding operation, it is possible to wind the segments  115  with a single continuous length of wire. 
     FIGS. 9 and 10  show the segments  115  after the winding operation discussed in connection with  FIG. 8  is complete.  FIG. 9  is a perspective view of the segments  115  and the ring clamp  120  including the spacers  122 . In  FIG. 9 , the segments  115  have been removed from the winding fixture  110 . Additionally, for simplicity, individual coil turns have not been shown in  FIG. 9 , but rather the coils are shown only schematically.  FIG. 10  is top view of the arrangement shown in  FIG. 9 , with individual coil turns shown. 
     FIG. 11  shows an assembly fixture  150 , and  FIG. 12  shows the segments  115  being mounted to the assembly fixture  150 . The segments  115  each comprise holes  152  that extend vertically through the segments  115 . The segments  115 , while they are still mounted in the ring clamp  120 , are placed onto the assembly fixture  120 , which comprises a plurality of guide pins  154  that extend through the holes  152 . The holes  152  and the pins  154  therefore cooperate to hold the segments in place within the assembly fixture  150 . Consequently, the ring clamp  120  including the spacers  122  may be removed, with the segments  115  being retained on the assembly fixture  120 , as shown in  FIG. 13 . 
   For a three phase motor, the process that has been described with respect to  FIG. 8  is performed two additional times for a total of three times, one time for each phase of the motor. In  FIG. 13 , the first set of segments  115  is combined with a second set of segments  116  such that the segments  115  and the segments  116  are disposed in a common circular arrangement, with the segments  116  fitting within the spaces between the segments  115  and vice versa.  FIG. 13  shows the second set of segments  116  in cutaway fashion, such that the fourth segment of the second set of segments  116  is not shown. 
     FIG. 14  shows the first set of segments  115  combined in a common circular arrangement with the second set of segments  116  and a third set of segments  117  to form a completed three phase stator. In  FIG. 14 , the rotatable clamp  120  and the assembly fixture  150  have both been removed, and the segments  115 - 117  are in the configuration needed for assembly into a motor housing. 
   From the foregoing description, a number of advantages of a winding fixture according to a second embodiment of the invention are apparent. First, the winding fixture  110  is constructed and arranged so as to permit segments to be wound with as a set with a single continuous length of wire. As a result, when the various sets of stator segments are combined, the number of manual interconnections that must be made is minimized. 
   Additionally, the winding fixture  110  achieves this advantage while making maximum use of existing bobbin winding technologies. The bobbin winder  132  may be similar to bobbin winders that have previously been used for winding unsegmented stators. As a result, the winding fixture  110  can be implemented in straightforward fashion by making maximum use of existing technologies. 
   Although two preferred embodiments of the invention have been described, it will be apparent to those skilled in the art that other embodiments are also possible. Many other changes and modifications may be made to the present invention without departing from the spirit thereof. The scope of these and other changes will become apparent from the appended claims.