Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    The present disclosure relates generally to dynamoelectric machines. More specifically, this disclosure relates to an apparatus for termination of conductors of a stator having six phases and concentrated leads in a vehicle alternator and method of manufacture of the apparatus. 
         [0002]    Electric machines, such as alternating current electric generators, or alternators, are well known. Prior art alternators typically include a stator assembly and a rotor assembly disposed in an alternator housing. The stator assembly is mounted to the housing and includes a generally cylindrically shaped stator core having a plurality of slots formed therein. The rotor assembly includes a rotor attached to a generally cylindrical shaft that is rotatably mounted in the housing and is coaxial with the stator assembly. The stator assembly includes a plurality of wires wound thereon, forming six phases. The stator lead wires are typically concentrated in a small area, perhaps even in consecutive slots, and are routed to and connected to a stator terminal assembly. 
         [0003]    Stators having six phases typically have stator terminal assemblies which include six electrically conductive tracks. One end of each conductive track is connected to the stator lead wires and another end is connected to a diode pair or similar switching elements of a rectifier bridge. To successfully dissipate diode heat, it is desirable to have the twelve (six pairs of) diodes physically spread out around the alternator circumference. The resultant conductive tracks, therefore, have one end in close proximity to each other (stator lead end) and another end spread out (diode pair end). At the stator lead end, the conductive tracks often interfere with each other and it is a common practice to partially dispose one track on top of another in the axial direction. This is vernacularly called a dual layer track stator terminal assembly. This results in a terminal assembly having a thickness that can in some instances block airflow within the alternator. Such conditions can present rectifier cooling issues. In addition, a dual layer track, if there were a way to reduce that thickness would be viewed as taking up valuable space that could be used, for example, for rectifier cooling fins. Furthermore, the dual layer track stator terminal assembly requires that each track be formed individually and is otherwise difficult and costly to manufacture because of the need to stack the individual tracks. Conversely, when a plurality of conductor tracks are arranged such that the tracks are not partially disposed on top of other tracks in the axial direction, these conductor tracks are considered as being disposed in a single layer. 
         [0004]    It is desirable, therefore, to provide a stator terminal assembly of a six phase alternator, with reduced thickness to alleviate properties of the electric machine such as rectifier cooling issues, and also to provide a stator terminal assembly of simplified manufacturability. 
       SUMMARY 
       [0005]    Disclosed herein is a terminal assembly for a stator of a dynamoelectric machine. The terminal assembly includes at least five electrically conductive tracks disposed in a single layer, each track of the at least five tracks configured and positioned for providing electrical communication between a rectifier bridge and at least one lead of a plurality of leads extending from the stator, at least five of which are disposed in an arc of less than ninety degrees of the circumference of the dynamoelectric machine. The at least five tracks are at least partially encapsulated in a nonconductive casing. 
         [0006]    The terminal assembly is manufactured by forming at least five tracks in a single layer from one piece of conductive material, each track of the at least five tracks remaining connected to adjacent tracks of the at least five tracks by a plurality of sprues. The tracks are at least partially encapsulated in a nonconductive case after which the plurality of sprues are severed, creating at least five individual tracks and thereby eliminating electrical communication between the at least five tracks. 
     
     
       DESCRIPTION OF THE DRAWINGS 
         [0007]    The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
           [0008]      FIG. 1  is a plan view of an embodiment of a single-layer stator terminal assembly. 
           [0009]      FIG. 2  is an enlarged partial plan view of a terminal assembly illustrating the terminal connectors. 
           [0010]      FIG. 3  is an enlarged partial perspective view of a terminal assembly illustrating the terminal connectors. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]    An embodiment of a single-layer stator terminal assembly  10  having six phases is shown in  FIG. 1 . The terminal assembly  10  includes a track set  30  and a track set  32 . The track set  32  is a mirror image of track set  30 , so track set  30  will be described in detail herein with the understanding that the description applies also to track set  32  unless otherwise noted. 
         [0012]    The track set  30  comprises a first track  12 , a second track  14 , and a third track  16 , arranged in a coplanar fashion. Each track includes one terminal connector  28  extending radially outwardly for connection to a stator lead wire, and two diode connectors  34  extending radially inwardly to connect the terminal assembly  10  to two diodes included in a rectifier bridge of an alternator assembly. 
         [0013]    The track set  30  is formed in one embodiment by a stamping process from one piece of copper or other conductive material, resulting in a track set  30  disposed in substantially a single layer with one or more sprues connecting individual tracks to adjacent individual tracks (i.e. sprues  36  connecting first track  12  to second track  14 , and sprues  56  connecting second track  14  to third track  16 ). Track set  32  is formed in the same manner. Track set  30  and track set  32  are then together at least partially encapsulated in insulating plastic material by an overmolding process. In the overmolding process, other features are also formed in the terminal assembly  10 , including attachment holes  38  which are used in securing the terminal assembly  10 . All sprues  36  and sprues  56  connecting the various individual tracks are then removed, thereby severing any undesired electrical connections between the individual tracks. 
         [0014]    As an alternative to forming track set  30  and track set  32  by separate processes, track set  30  and track set  32  may be formed simultaneously from the same piece of copper or other conductive material. The result being a track set  30  and a track set  32  with one or more sprues  58  connecting individual tracks of track set  30  to individual tracks of track set  32  (i.e. sprues  58  connecting the third track  16  of track set  30  to the third track  16  of track set  32 ). 
         [0015]    After forming the track set  30  and track set  32  simultaneously as described. The track set  30  and track set  32  are then at least partially encapsulated in an insulating plastic material by an overmolding process. The sprues  36 , sprues  56 , and sprues  58  connecting individual tracks to adjacent individual tracks are then broken, thereby severing an undesired electrical connection between the individual tracks. 
         [0016]    Forming the individual tracks as track set  30  (or the combined track set  30  and track set  32 ) as described above instead of individually can simplify the manufacturability of the terminal assembly  10 . The process as described has the benefits of reducing time and cost associated with the stamping process. The cost of the molding process is also reduced because only one (or two) track sets are loaded into a mold die versus six individual tracks that must be loaded into a mold die in the conventional process. 
         [0017]    In addition to the manufacturability benefits, the terminal assembly  10  also improves cooling performance of a dynamoelectric machine into which it is installed. The single-layer configuration results in a thinner terminal assembly  10  in the axial direction, thereby allowing more internal airflow in the dynamoelectric machine which enhances cooling performance. Additionally, the thinner terminal assembly  10  leaves more available space in the dynamoelectric machine for other components, including rectifier heatsink fins, which may also have the benefit of enhancing cooling performance. 
         [0018]    To facilitate a single-layer configuration, and still locate diode connectors  34  and terminal connectors  28  in desired locations, other unique elements are employed. First, in a conventional multi-layer track design the first track and the second track are both routed radially outwardly of an attachment hole. To achieve this, the tracks are layered one over the other. The terminal assembly  10 , on the other hand, maintains a single layer by routing the first track  12  radially outwardly of attachment hole  38  and routing the second track  14  radially inwardly of attachment hole  38 . Furthermore, in areas where the insulating plastic material might be located close to other features of the terminal assembly  10 , local areas of the second track  14  might be required to remain exposed from the insulating plastic. Such a local area can be seen located radially inward of attachment hole  38  wherein the second track  14  is located close to two diode connecters  34 . Locally exposing the second track  14  allows for proper clearance for an overmolding die of the overmolding process. 
         [0019]    Third track  16  includes a tab  44  extending radially outwardly from an end opposite an end including the terminal connector  28 . A tab hole  46  is located in the tab  44 . During the overmolding process described above, plastic material flows into the tab hole  46  and cures, thereby forming a retention device to more effectively secure the third track  16  in the terminal assembly  10 . Second track  14  extends radially outwardly in the local area  48  around tab  44  to maintain the single layer track configuration and also to maintain the desired width of second track  14 . First track  12 , in turn, extends radially outwardly in the local area  50  to maintain a single layer track configuration and also to maintain a desired width of first track  12 . 
         [0020]      FIG. 2  and  FIG. 3  illustrate terminal assemblies  10  where the terminal connectors  28  are concentrated over less than approximately 90 degrees of circumference of the alternator. This concentration of the terminal connectors  28  may be desirable to mate a terminal assembly  10  to a stator design that requires the stator lead wires to exit a stator core from adjacent core slots. Conventional crimp legs, all formed at substantially the same axial position, may interfere with one another (in the flat state) when stamped from a single piece of copper. Alternatively the conventional crimp legs may be shortened to alleviate the interference, but when the shortened conventional crimp legs are crimped around a stator lead wire, their shortened length of the crimp length may be insufficient to retain a stator lead wire. 
         [0021]    To solve the above described problem, each terminal connector  28  shown in  FIG. 2  and  FIG. 3  comprises an upper crimp leg  40  and a lower crimp leg  42 . The upper crimp legs  40  and lower crimp legs  42  are disposed in different axial locations as best seen in  FIG. 3 . The axial direction is defined as being co-axial with a rotor shaft of the alternator. When the terminal connectors  28  are in a stamped flat state as shown if  FIG. 3 , the upper crimp leg  40  of an individual track will be disposed radially outwardly of the lower crimp leg  42  of an adjacent individual track. The upper crimp leg  40  and the lower crimp leg  42  can thus be formed to a sufficient length to effectively retain a stator lead without interfering with crimp legs of adjacent terminal connectors  28 . This crimp leg configuration allows terminal connectors  28 , which are closely spaced to each other, to be stamped from a single piece of copper. 
         [0022]    While embodiments of the invention have been described above, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.

Technology Category: 5