Abstract:
A stator for a vehicle alternator, wherein the stator includes continuous coils which are wound and inserted from an inner diameter of the stator core resulting in a non-interfering front-to-back configuration.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to an alternator for an automobile and more particularly to a stator for an alternator, the stator having continuous coils which are wound and inserted from an inner diameter of the stator core and having a non-interfering front-to-back configuration.  
         BACKGROUND OF THE INVENTION  
         [0002]    Traditionally, the electrical loads of an automobile such as lighting systems, radios, windshield wipers, and horns, for example, receive electrical power from an on-board electrical power storage device such as a 12-volt (nominal) battery, for example. The 12 volt battery is charged by an alternator operating at about 14 volts, and the voltage from the alternator and/or 12 volt battery is used as a standard electrical power input for the varied types of electrical loads placed on the automobile, including continuous loads, prolonged loads, and intermittent loads. The vehicle battery and the alternator have been increasingly called upon to supply electrical power to accessories of a vehicle. For example, electrically pre-heated catalytic converters, electrically power-assisted steering, and seat and windshield heaters are now commonplace, as are other power consumers.  
           [0003]    A stator winding is used in an automobile alternator and is produced using a wire assembled with a stator core. The conventional winding process, however, utilizes a round cross sectional wire, irregular shaped core slots, and a random type winding process, which results in a stator with a low slot fill factor and high end loop heights. These two characteristics cause the alternator to exhibit low output and efficiency. Additionally, with more and more electrical accessories being included in a vehicle, output levels, efficiency levels, compactness, and noise emissions from the alternator are of greater concern.  
           [0004]    Recent improvements made, however, require a complicated winding process, due to the numerous welds required between individual conductors or between individual layers.  
           [0005]    It would be desirable to produce a stator for an automobile alternator which is produced using a plurality of continuous coils per phase, and where each of the plurality of coils is wound and inserted in a slot from an inner diameter of the stator core and is arranged in a non-interfering front-to-back configuration with respect to the slot and the other coils.  
         SUMMARY OF THE INVENTION  
         [0006]    Consistent and consonant with the present invention, a stator for an automobile alternator which is produced using a plurality of continuous coils and where each of the plurality of coils is wound and inserted in a slot from an inner diameter of the stator core and is arranged in a non-interfering front-to-back configuration with respect to the slot, has surprisingly been discovered.  
           [0007]    The stator for an automobile alternator comprises:  
           [0008]    a generally cylindrical hollow stator core having an annular array of slots formed in an inner surface thereof, the slots extending radially outwardly from the inner surface and having a substantially constant width;  
           [0009]    a plurality of continuous conductors having a cross section adapted to be radially inserted into the slots of the stator core, a width of each of the conductors being substantially equal to the width of each of the slots of the stator core. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The above, as well as other objects, features, and advantages of the present invention will be understood from the detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 is an end view of a stator for an automobile alternator incorporating the features of the invention and showing phase one of a six phase, 72 slot, 3 layer stator;  
         [0012]    [0012]FIG. 2 is an enlarged partial cross sectional view of the stator illustrated in FIG. 1 showing the stator core slot and wire cross sections contained in the slot using a rectangular continuous conductor and wherein the conductor is aligned in one radial row of each slot;  
         [0013]    [0013]FIG. 3 is a partial cross sectional view of a stator of the prior art showing the stator core slot and wire cross sections contained in the slot using a round continuous conductor;  
         [0014]    [0014]FIG. 4 is a partial cross sectional view of a stator of the prior art showing the stator core slot and wire cross sections contained in the slot using rectangular, u-shaped, axially inserted, and welded conductors;  
         [0015]    [0015]FIG. 5 is a schematic view of a partial winding portion of a stator for an automobile alternator incorporating the features of the invention and showing phase 1 of a six phase, 36 slot, 3 layer stator;  
         [0016]    [0016]FIG. 6 is a top view of the winding shown in FIG. 5; and  
         [0017]    [0017]FIG. 7 is a schematic view of a winding prior to insertion into the stator incorporating the features of the invention and showing all six phases of a six phase, 24 slot, 2 layer stator and having the first conductor of the first phase highlighted.  
         [0018]    [0018]FIG. 8 is a cross sectional elevational view of an alternator including a stator according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Referring now to the drawings, and particularly FIG. 1, there is shown generally at  10  a stator incorporating the features of the invention. Phase one of a six-phase stator is shown. The stator  10  includes stator core  12 . The stator core  12  is an annular ring having an inner surface  14 , an outer surface  16 , a first side  18  and a second side  20 , shown in FIG. 8. An annular array of slots  22  is formed on the inner surface  14  of the stator core  12 , the slots  22  extending radially outwardly from the inner surface  14 . In the embodiment shown, seventy-two slots  22  are included. It is understood that more or fewer slots could be used as desired.  
         [0020]    A first conductor or wire  24  and a second conductor or wire  26  are alternatingly wound in the stator core  12 . The first conductor  24  and the second conductor  26  cooperate to form a first phase of a six-phase conductor. Each of the first conductor  24  and the second conductor  26  are formed from a single continuous wire. As illustrated, the first conductor  24  has a lead extending perpendicularly out of the drawing figure and the second conductor  26  has a lead extending perpendicularly into the drawing figure. Three full revolutions are made by each of the first conductor  24  and the second conductor  26  to form a first layer  28 , a second layer  30 , and a third layer  32 . In order to form the three distinct layers, a transition occurs in a transition zone  34 . It is understood that more or fewer layers could be used as desired.  
         [0021]    [0021]FIG. 2 is an enlarged partial cross sectional view of the stator  10  illustrated in FIG. 1 showing the stator core  12 , two of the slots  22 , the first conductor  24  and the second conductor  26 . A third conductor  36  and a fourth conductor  38  (not shown in FIG. 1) are shown and cooperate to form a second phase of the six-phase stator. In the illustrated embodiment, the cross sectional shape of each of the first conductor  24 , the second conductor  26 , the third conductor  36 , and the fourth conductor  38  is rectangular. It is understood that other cross sectional shapes could be used without departing from the scope and spirit of the invention. An insulating layer  40  is disposed between the conductors  24 ,  26 ,  36 ,  38  and the stator core  12 . The slots  22  as more clearly illustrated in FIG. 2, have a generally u-shaped cross section having a main width, including any insulation (not shown), substantially equal to the width of the conductors  24 ,  26 ,  36 ,  38 , which includes any insulation (not shown), and are adapted to receive the conductors  24 ,  26 ,  36 ,  38  aligned in one radial row. The slots  22  may have an opening width at the inner surface  14 , which is smaller then the main width of the slots as shown in FIG. 4. In this case, the conductors  24 ,  26 ,  36 ,  38  may be inserted through these small slot openings, but still fit closely to the main width of the slots, by temporarily shrinking the width of the conductor or by temporarily enlarging the slot opening to accept the conductors. A depth of the slots  22  is substantially equal to the total serial depth of the number of conductors  24 ,  26 ,  36 ,  38 , in the embodiment shown.  
         [0022]    Referring now to FIG. 8, there is shown a cross sectional elevational view of an alternator  50  including the stator  10  according to the present invention. The stator shown is a two layer stator. The alternator  50  includes the stator  10 , serving as an armature, and a rotor  52 , serving as a field, contained within a housing  54 . The rotor  52  integrally rotates with a shaft  56  which is rotatingly disposed within the housing  54 . The general operation of an alternator is well known by one skilled in the art, as is disclosed in U.S. Pat. No. 5,998,903.  
         [0023]    Embodiments of prior art structures are illustrated in FIGS. 3 and 4. FIG. 3 shows a stator core  112  having a plurality of slots  122  formed therein. The slots  122  have a generally u-shaped cross section with a pair of detents  123  formed on opposite sides of an inlet to the slots  122  and facing one another. A continuously wound conductor  124  having a circular cross section is radially inserted in the slots  122 . The diameter of the conductor  124  is smaller than a distance between the detents  123  and does not fit closely to the sides of the slots  122 .  
         [0024]    [0024]FIG. 4 shows a stator core  212  having a plurality of slots  222  formed therein. The slots  222  have a generally u-shaped cross section with a pair of detents  223  formed on opposite sides of an inlet to the slots  222  and facing one another. A plurality of conductors  224  having a rectangular cross section are inserted axially in the slots  222  and welded to one another to form a continues winding. The width of the conductors  224  is larger than the distance between the detents  223 . The conductors  224  are not continuous.  
         [0025]    The production of the stator  10  will now be discussed. As indicated previously, the cross-section of the conductors  24 ,  26 ,  36 ,  38  is rectangular in shape and fits closely to the width of the slots  22 . The conductors  24 ,  26 ,  36 ,  38  of each of the slots  22  are aligned in one radial row. Each phase of the stator  10  is comprised of only two continuous conductors, regardless of the number of desired electrical turns. The two conductors of each phase are aligned in multiple layers. In each layer, the two conductors alternate radial forward and rearward slot positions of that layer with respect to each other. Additionally, the transition zone between layers permits the two conductors to pass from one layer to the next layer but also remain in alternating radial positions with respect to each other. An end loop one of the conductors is interlaced with an end loop of the other conductors to militate against interferences.  
         [0026]    FIGS.  5 - 7  illustrate how the stator  10  is produced. Let:  
         [0027]    n=the number of phases (numbered 1 through n).  
         [0028]    m=the number of winding slots in the stator core  12  (numbered 1 through m).  
         [0029]    z=the total number of slots  22  in the stator core  12 .  
         [0030]    S 1 =the first side  18  of the stator core  12 .  
         [0031]    S 2 =the second side  20  of the stator core  12 .  
         [0032]    L=the number of layers (a layer is defined as the portion of conductors  24 ,  26 ,  36 ,  38  that traverse around the stator core  12  for one revolution).  
         [0033]    A=a first conductor of a layer.  
         [0034]    B=a second conductor of a layer.  
         [0035]    For simplicity, the first phase of a six phase, 36 slot, 3-layer winding is illustrated. Referring to FIG. 5, the first phase is produced by beginning with the layer L=1. In the slot z=1, a first lead  42  of the conductor A is located on the side S 1  of the core in the radial rear portion of the first layer and a first lead  44  of conductor B is located on the side S 2  of the core  12 , in the radial front portion of the layer L=1. From the slot z=1, conductor A extends from the side S 2  of the core  12  and shifts radially inward and circumferentially toward slot z=n+1 where it is located in the radial front portion of the layer L=1. Conductor B extends from the side S 1  of the core  12  and shifts radially outward and circumferentially toward slot z=n+1 where it is located in the radial rear portion of the layer L=1. Conductors A and B continue around the core  12  alternating radial rear and radial front portions of the layer L=1 and extend on alternating sides of the core, until they both reach slot number z=m−n+1. This wind completes the layer L=1.  
         [0036]    For the layer L=2, conductor A extends from the side S 2  of the core  12  from slot z=m−n+1 and shifts radially inward and circumferentially toward the slot z=1, where it enters the radial rear portion of the layer L=2. Conductor B extends from the side S 1  of the core  12  and shifts radially inward and circumferentially toward the slot z=1, where it enters the radial front portion of the layer L=2. Conductors A and B continue circumferentially around the core  12  similar to the layer L=1 until they both reach the slot z=m−n+1.  
         [0037]    The layer L=3 is completed in the same manner as layer L=2.  
         [0038]    After the layer L=3 is finished, conductor A terminates as a second lead  46  on the side S 1  of the core  12  and conductor B terminates as a second lead  48  on side S 2  of the core  12 .  
         [0039]    The phases 2-n are completed the same as phase n=1, except each phase is shifted over one circumferential slot z with respect to the previous phase.  
         [0040]    All phases of a 6 phase, 24 slot, 2 layer winding are illustrated in FIG. 7, showing the winding prior to insertion into the stator core. Conductor A′ of the first phase is highlighted for clarity.  
         [0041]    The conductors A and B can be connected together in series to form a stator with 2L number of electrical turns, or alternatively in parallel to form a stator with L number of electrical turns. The phases of the stator  10  are connected to a rectifier (not shown) in any conventional manner such as a wye or a ring configuration, for example, to convert the generated AC current into DC current.  
         [0042]    For the finished stator of this disclosure, conductor A′ leads  42 ′,  46 ′ are located on the side S 1 ′ and conductor B′ leads  44 ′,  48 ′ are located on the side S 2 ′. To connect the conductor A′ leads  42 ′,  46 ′ and conductor B′ leads  44 ′,  48 ′ to a rectifier, a first rectifier is positioned on the side S 1  of the stator core, and the conductor B′ leads  44 ′,  48 ′ are routed around the outer diameter of the stator core to permit easy connection to the first rectifier.  
         [0043]    To militate against end loop interferences, the end loops are interlaced, as schematically shown in FIG. 7. The end loop of the first phase exits one of the slots  22  and rises above the end loop of the adjacent phase at an angle. At the apex of the rise, the end loop of the first phase is jogged radially outward to allow the adjacent end loop to continue on its own apex, which is located one slot angle away from the apex of the end loop of the first phase. The end loop of the first phase lowers back towards the core behind the end loop of the adjacent phase and enters its respective one of slots  22 . This is repeated around the core such that there are zero interferences between end loops of adjacent phases.  
         [0044]    The winding of the stator  10  is assembled outside of the stator core  12 . Referring again to FIG. 7 as well as FIG. 1, the conductor A′ and the conductor B′ of each phase form a plurality of straight portions  60 ′ having alternating end loops. The conductor A′ and the conductor B′ of all the phases, are combined outside of the stator core such that all of the end loops are interlaced as previously described and for each phase, the straight portions  60 ′ of the conductor A′ align and alternate forward/rearward positions with the conductor B′. The layers are aligned in a linear fashion with the second layer to the right of the first layer, the third layer to the right of the second layer, and so forth.  
         [0045]    To insert the winding in the stator core  12 , the end pair of aligned straight portions  60 ′ are inserted into the first of the slots  22 , the next straight portion pairs are then inserted sequentially into adjacent slots  22  around the stator core  12  to the transition zone  34  to complete the first layer. At the transition zone  34 , the next straight portion pairs are inserted into the first of the slots  22 , lying radially inward of layer number 1. The next straight portion pairs are then inserted sequentially into adjacent slots  22  around the stator core  12  to the transition zone  34  to complete the second layer. To form a third layer as shown in FIG. 1, at the transition zone  34 , the next straight portion pairs are inserted into the first of the slots  22 , laying radially inward of layer number 2. The next straight portion pairs are then inserted sequentially into adjacent slots  22  around the stator core  12  to the transition zone  34  to complete the third layer. For additional layers L, the last n straight portions are the second leads of the n phases.  
         [0046]    There are several advantages to the present invention. First, since there are two continuous conductors per phase, there are no required internal conductor connections. Second, alternator output and efficiency are improved because of the high slot fill stator design, which is the result of the rectangular shaped conductors, which fit closely to the width of the rectangular shaped slots. Slot fill is defined as the conductor cross sectional area in one slot divided by the area of that slot. Additionally, the manufacturing ease is improved, because the conductors alternate radial positions throughout the entire winding (including the transitional areas), which allows the manufacturing of the windings to be consistent and not to have require special transitional methods.  
         [0047]    From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.