Abstract:
A three-phase connector carries all three phases in one connector and keeps the phases properly isolated from each other and the motor case. The three-phase connector has metal connector components that are spaced from one another and supported in a nylon over molding covering each of the connector components, except for upper and lower exposed ends of the connector components, which are each drilled and tapped to receive bolts. First and second connector components extend above and below a flange of the three-phase connector with their respective exposed upper and lower ends offset in different planes than the exposed upper and lower ends of the third connector component.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation of U.S. patent application Ser. No. 09/682,976 filed Nov. 5, 2001, now U.S. Pat. No. 6,572,416 now allowed, which application is incorporated herein by reference in its entirety. 

   BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The present invention relates generally to the field of electric machines, and more particularly to a three-phase connector for an electric vehicle drivetrain. 
   2. Background of the Invention 
   Phase connectors are connectors which carry current, for example, from the internally gated bipolar transistors (IGBT&#39;s) of an inverter to an electric motor. The IGBT is the power transistor in the inverter and generates the sine wave for the three-phase current. It is not possible to simply thread the wires for the three phases through an opening in the electric motor housing because the current carried through the phase connections is very high, such as 350-400 amps. In carrying the three-phase current from the IGBT of the inverter to a three-phase induction motor, the three phases must remain isolated, and it is necessary to have some kind of connector which isolates the phases from each other. 
   Previously, three separate connectors were used to carry the three-phase current to the electric motor. Fig. shows a cross-sectional view of such a prior art separate phase connector  2 . All three separate connectors were required to isolate the electric current from the motor housing as it passed through from the inverter. With separate phase connectors, each of the three individual connectors carries a separate phase current through a separate opening in the motor casing and is fastened with a separate set of fasteners. Thus, separate phase connectors require many different parts and must each be individually bolted to the housings with separate holes drilled for each connector. The resulting package was large, costly, and required significant effort to assemble. 
   SUMMARY OF INVENTION 
   It is a feature and advantage of the present invention to provide a three-phase connector that carries all three phases in one connector, while keeping all the phases properly isolated from each other and from the motor case. 
   To achieve the stated and additional features, advantages and objects, an embodiment of the present invention provides a three-phase connector that carries all three phases in one connector and keeps all the phases properly isolated from each other and the motor case. The three-phase connector has three separate metal inserts which act as each phase carrying electrical current to a three-phase induction motor. The three inserts are all molded into one plastic housing, which reduces the size and cost of the part, and reduces the effort required to assemble the drivetrain. 
   An embodiment of the present invention provides a three-phase connector, for example, for an electric vehicle drivetrain, utilizing two or more, and preferably three electrically conductive connector components, that are spaced from one another and supported in an over molding of electrically insulating material covering each of the connector components, except for upper and lower exposed ends of the connector components, and also forming a supporting flange. First and second ones of the connector components are spaced farther apart from one another than they are from a third connector component that is disposed, for example, between them. The first and second connector components extend above the flange with their respective exposed upper ends offset in different planes than the exposed upper end of the third connector component. The first and second connector components also extend below the flange with their respective exposed lower ends disposed in different planes than the third connector component. 
   In addition, the upper exposed ends of the first and second connector components are disposed a different and preferably shorter distance above the flange than the exposed upper end of the third connector component, and the respective lower exposed ends of the first and second connector components are disposed a different and preferably greater distance below the flange than the exposed lower end of the third connector component. Further, each of the connector components has an upper portion that extends a pre-defined distance above the flange and a lower portion that extends a greater distance below the flange than the pre-defined distance above the flange. 
   An electrically insulating material, such as nylon, is used for the over molding, and each connector component is made of an electrically conducting metal, such as tellurium copper, that is machined and over molded with the electrically insulating material. Each connector component is drilled at its upper and lower ends and tapped internally to receive a threaded bolt, for example, for a busbar or a lead. Each connector component has an exterior wall with one or more undercuts that provide an anchor for the over molding material. The flange is provided with openings to receive fasteners for attaching the flange to a housing. An alternate embodiment includes, for example, partitions formed by the over molding that extend upward from the flange between each of the first and second connector components and the third connector component. 
   Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become more apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  shows a cross-sectional view of a prior art separate phase connector; 
       FIG. 2  shows a schematically arranged cut-away cross-sectional view of an inverter coupled to an electric motor by the three-phase connector for an embodiment of the present invention; 
       FIG. 3  is a cross-sectional view of the three-phase connector shown in  FIG. 2  for an embodiment of the present invention; 
       FIG. 4  is a perspective view of the three-phase connector shown in  FIGS. 2 and 3  for an embodiment of the present invention; 
       FIG. 5  is a perspective view of the three-phase connector with partitions for an alternate embodiment of the present invention; and 
       FIG. 6  is an enlarged partial view of a portion of one of the connector components shown in  FIG. 3  illustrating an example of undercuts provided in each connector component for an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   An embodiment of the present invention will now be described in detail with reference to the accompanying drawings wherein like reference numerals will be used to describe like components. Referring to  FIG. 2 , the three-phase connector  10  makes the connection between the inverter  12  and the electric motor  14 . Disposed between the three IGBT&#39;s  16  of the inverter  12  and the three-phase connector  10  is a busbar (not more particularly shown), which connects the IGBT&#39;s  16  of the inverter  12  to the three-phase connector  10 . The three-phase connector  10  sits on a casting  18 , which is the housing for the electric motor  14 , and the inverter  12  also has a housing or casting  20 . The task of the three-phase connector  10  is to get the three-phase current through those two castings  18 ,  20  to the windings for the electric motor  14 . 
   Referring to  FIGS. 2-4 , the three phases are isolated at least in part with a nylon over molding  24  of the three-phase connector  10 , which covers three metallic connector components  26 ,  28 ,  30 , except for the upper exposed ends  32 ,  34 ,  36  and the lower exposed ends  38 ,  40 ,  42  of the three metallic connector components  26 ,  28 ,  30 , and which also forms a supporting flange  44 . When the three-phase connector  10  is installed, the connector components  26 ,  28 ,  30  are vertically oriented. In an automotive powertrain environment in which the three-phase connector  10  is used, it must be secured to hold it in place against vibration, and the three phases must be isolated from one another and from the housings. 
   The three-phase connector  10  for an embodiment of the present invention replaces all the separate parts of the prior art separate connector  2  as shown in FIG.  1  and requires the drilling of only one opening in the housing  18 ,  20 . Thus, the three-phase connector  10  replaces the three prior art separate connectors with a single component  10  in the assembly, and only a single aperture is required to bolt the flange  44  of the three-phase connector  10  onto the casting  18 . In addition, a seal or gasket (not more particularly shown) is provided beneath the flange  44  to seal the castings  18 ,  20  against intrusion, for example, of water, oil and other environmental contaminants. 
   Each connector component  26 ,  28 ,  30  of the three-phase connector  10  has an upper portion  46 ,  48 ,  50  which extends a pre-defined distance above the flange  44  and a lower portion  52 ,  54 ,  56  which extends a greater distance below the flange  44  than above the flange  44 , and the lower portions  52 ,  54 ,  56  extend through the casing  18 . The outer two connector components  26 ,  30  are offset relative to the center connector component  28 . In other words, the two outer connector components  26 ,  30  extend in a different plane from, and a shorter distance above and greater distance below the flange  44 , than the center connection component  28 , to provide isolation between the three phases. The three phases must be isolated because they carry, for example, 300-400 amps, and isolation is provided between the fields at least in part by the air gap maintained between the connector components  26 ,  28 ,  30  disposed in different planes. Spacing the connector components  26 ,  28 ,  30  vertically in this way provides a greater air gap between the exposed metal at upper ends  32 ,  34 ,  36  and lower ends  38 ,  40 ,  42  of connector components  26 ,  28 ,  30  than would be provided simply by the horizontal distance between the connector components  26 ,  28 ,  30 . 
     FIG. 5  is a perspective view of a three-phase connector with partitions for an alternate embodiment of the present invention. In this alternate embodiment, isolation between the three phases is provided at least in part by partitions  60 ,  62 , also formed by the over molding  24  of nylon, between the connector components  26 ,  28 ,  30 . Thus, in the event greater isolation is required between the connector components  26 ,  28 ,  30  disposed in different planes, or if design considerations require that the connector components  26 ,  28 ,  30  be disposed in or closer to the same plane, the isolation can be provided at least in part by the partitions  60 ,  62 . 
   Referring again to  FIGS. 2-4 , the connector components  26 ,  28 ,  30  of a three-phase connector  10  an embodiment of the present invention are made of metal that is machined and over molded with an electrical insulating material, such as nylon. Thus, each of the metal connector components  26 ,  28 ,  30  forms the core of a cylindrical over molding  24  of nylon with an exposed upper end  32 ,  34 ,  36  and an exposed lower end  38 ,  40 ,  42 , which extends beyond the nylon over molded portion of each metal connector component  26 ,  28 ,  30 . Each metal connector component  26 ,  28 ,  30  is drilled and tapped internally for a threaded fastener at its upper end  64 ,  66 ,  68  and lower end  70 ,  72 ,  74 . 
   The tapped upper ends  64 ,  66 ,  68  of the metal connector components  26 ,  28 ,  30  extending above the flange  44  of the three-phase connector  10  are threaded to receive the threaded bolts of a busbar, such as a rigid busbar, shown schematically by arrows  76 ,  78 ,  80  in  FIG. 2 , in a separate busbar plane for each of the three phases. The tapped lower ends  70 ,  72 ,  74  of the metal connector components  26 ,  28 ,  30  extending below the flange  44  are threaded to receive the threaded bolts of leads, such as flexible wire leads, shown schematically by arrows  82 ,  84 ,  86  in  FIG. 2 , from the electric motor  14 . 
   Referring further to  FIG. 4 , the flange  44  of the three-phase connector  10  for an embodiment of the present invention is provided with openings  90 - 100  to receive fasteners, such as fastening bolts (not more particularly shown), for attaching the three-phase connector  10 , for example, to the electronics housing  20 . In addition, a seal or gasket  27  (illustrated as flipped over to reveal the side which is adjacent the flange  44  when in use) on the bottom surface of the flange  44  provides a seal between the two housings  18 ,  20 . The seal or gasket  27  is disposed beneath the flange  44  and is generally the same shape as the flange  44 , with openings  29  through which the bottom portions  52 ,  54 ,  56  of the connector components  26 ,  28 ,  30  extend and additional openings corresponding to the fastener openings  90 - 100  for the fasteners to extend. 
   Previously, three separate prior art individual connectors, such as individual connector  2  shown in  FIG. 1 , were used to carry the three phases of current from the inverter  12  to the electric motor  14 . They were entirely separate parts and were not physically connected to one another in any way. It was necessary to fasten each separate connector individually to the electronics housing  20  with its own fasteners and its own seal or gasket. The three-phase connector  10  for an embodiment of the present invention eliminates the redundant fasteners and gaskets and combines the entire functionality into one component. 
   In an embodiment of the present invention, the nylon over molding  24  serves as insulation as well as to provide structural integrity of the three-phase connector  10 . The metal connector components  26 ,  28 ,  30  of the three-phase connector  10  are made of a highly electrically conductive metal, such as tellurium copper, which is in the range of ninety-five percent copper.  FIG. 6  is an enlarged partial view of a portion of one of the connector components  30  shown in FIG.  3 . Referring to  FIG. 6 , the exterior wall of each metal connector component  26 ,  28 ,  30  includes one or more undercuts  102 ,  104  for proper sealing. The undercuts  102 ,  104  provide an anchor for the nylon over molding  24  and form a friction interface between the nylon over molding  24  and the exterior wall of each metal connector component  26 ,  28 ,  30 . 
   The undercuts  102 ,  104  are provided in the exterior wall of each metal connector component  26 ,  28 ,  30  because it has been found that a smooth exterior wall forms a relatively poor seal between the exterior wall and the nylon over molding  24  thereby allowing an unacceptable degree of leakage between the exterior walls of the metal connector components  26 ,  28 ,  30  and the nylon over molding  24 . When the nylon absorbs moisture, it tends to expand away from the smooth exterior wall of the metal connector components  26 ,  28 ,  30 . However, when the nylon over molding  24  disposed in the undercuts  102 - 104  in the exterior wall of the connector components  26 ,  28 ,  30  absorbs moisture and expands, it actually seals itself to the exterior walls of the connector components  26 ,  28 ,  30 . The undercuts  102 - 104  in the exterior wall of the connector components  26 ,  28 ,  30  provide, for example, additional profiles for the nylon over molding  24  and create a better seal between the exterior walls of the connector components  26 ,  28 ,  30  and the nylon over molding  24 . 
   Referring again to  FIG. 2 , it is important that the seal between the nylon over molding  24  and the exterior walls of the connector components  26 ,  28 ,  30  creates a vapor barrier between the upper and lower housings  20 ,  18 . For example, the electric motor housing  18  can contain air with oil mist in it that must be kept out of the electronics. In some cases, the three-phase connector  10  may be used as an exterior connector to the environment, in which case there may be rain or water mist that must likewise be kept out of the electronics. In addition, the gasket beneath the flange  44  of the three-phase connector  10  seals the three-phase connector  10  to the cast housing  18 ,  20  and prevents moisture from passing between the housings  18 ,  20 . 
   Various preferred embodiments of the invention have been described in fulfillment of the various objects of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention.