Patent Publication Number: US-2021194308-A1

Title: Busbar for electric machine

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 62/950,730 filed Dec. 19, 2019, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Exemplary embodiments pertain to the art of electric machines and, more particularly, to a bracket for securing a bus bar to a stator of an electric machine. 
     Electric machines include a stator having stator windings mounted to a housing and a rotor including rotor windings that rotates relative to the stator. The stator windings may be excited to impart a rotational forces on the rotor or, the rotation of the rotor may induce an electrical current in the stator windings. In the first operating mode, electrical current passes to the stator windings in the second operating mode, electrical current passes from the stator windings. As such, the stator windings are connected in a selected pattern and provided with terminals for connecting with an eternal device e.g., an external power source or an external load. 
     Currently, windings are connected by twisting and welding or soldering the winding ends. A circuit mount, into which the wires are inserted, is frequently used as insulation between the phases in the area of the winding ends. Terminals may be connected to select ones of the winding ends. The terminals provide an external interface. The winding ends are typically insulated and tucked out of the way in a housing of the electric machine. The electric machine is subjected to vibrations that may be caused by operation of the electric machine itself or from external environmental factors. Vibrations may cause the winding connections to weaken causing disruptions in operation. Accordingly, the industry would welcome a system that provides structural support for winding connections and terminals reduces operational interruptions. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Disclosed is an electric machine including a housing, a rotor rotatably mounted in the housing a stator fixedly mounted to the housing. The stator includes a stator core and a plurality of stator windings supported by the stator core. The stator core surrounds the rotor. A busbar including a plurality of electrically conductive members is coupled to the stator windings and an insulating cover extends across at least a portion of the electrically conductive members. A bracket is coupled to the busbar and one of the stator core and the housing, the bracket supporting the busbar in the housing. 
     Also disclosed is a stator including a stator core, a plurality of stator windings supported by the stator core, a busbar including a plurality of electrically conductive members coupled to the stator windings and an insulating cover extending across at least a portion of the electrically conductive members. A bracket is coupled to the busbar and the stator core. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  depicts an electric motor including a busbar and support bracket, in accordance with an aspect of an exemplary embodiment; 
         FIG. 2  depicts a perspective view of the busbar and support bracket, in accordance with an aspect of an exemplary embodiment; 
         FIG. 3  depicts the busbar and support bracket secured to a stator core, in accordance with an exemplary aspect; 
         FIG. 4  depicts the support bracket, in accordance with an aspect of an exemplary embodiment; 
         FIG. 5  depicts the support bracket secured to an outer surface of a stator core, in accordance with an exemplary aspect; 
         FIG. 6  depicts a busbar mounted to the support bracket of  FIG. 5 , in accordance with an exemplary aspect; 
         FIG. 7  depicts a busbar and support bracket mounted to a stator core, in accordance with another aspect of an exemplar embodiment; 
         FIG. 8  depicts a busbar and support bracket mounted to a stator core, in accordance with yet another aspect of an exemplar embodiment; 
         FIG. 9  depicts a busbar and support bracket mounted to a stator core, in accordance with still yet another aspect of an exemplar embodiment; 
         FIG. 10  depicts the busbar and support bracket of  FIG. 9  showing electrically conductive members coupled to a terminal block in the electric motor, in accordance with an aspect of an exemplar embodiment; 
         FIG. 11  depicts a perspective view busbar and support bracket positioned at a stator core, in accordance with another aspect of an exemplary embodiment; 
         FIG. 12  depicts an upper view of the busbar and bracket of  FIG. 11 ; and 
         FIG. 13  depicts the bracket of  FIG. 9  mounted to a terminal block of the electric motor, in accordance with an aspect of an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     With initial reference to  FIG. 1 , an electric motor in accordance with an exemplary embodiment, is indicated generally at  10 . Electric motor  10  includes a housing  14  having an outer surface  16  and an inner surface  18  that defines an interior  20 . Housing  14  includes a first end wall  23  and an opposing second end wall  25 . One of the first and second end walls  23 ,  25  may be integrally formed with housing  14  while another of the first and second end walls  23 ,  25  may be removable. Of course, both the first and second end walls  23  and  25  may be removable. First end wall  23  includes an opening  27 . 
     Electric motor  10  includes a rotor  40  rotatably mounted in interior  20 . Rotor  40  includes a shaft  43  which supports a rotor core  45  surrounded by a plurality of rotor windings  48 . Shaft  43  includes a first end (not separately labeled) that extends through opening  27  and is supported by a first bearing  50 . First bearing  50  may be mounted to first end wall  23 . Shaft  43  also includes a second end (also not separately labeled) that is supported at second end wall  25  by a second bearing  52 . Rotor  40  is rotatable relative to a stator  58  mounted to, for example, inner surface  18 . Stator  58  may also be mounted to, for example, second end wall  25 . Stator  58  includes a stator core  60  that supports a plurality of stator windings  62 . Stator windings  62  are connected to a busbar  64  that provides an interface with a terminal block (not shown) that, in turn, acts as an interface with a motor input or a motor output (also not shown) depending on operating mode. 
     Referring to  FIGS. 2 and 3 , busbar  64  includes a plurality of electrically conductive members  72  that are shielded by an insulating cover  74 . Plurality of electrically conductive members  72  includes a first end  78  that interfaces with the terminal block and a second end  80  that is connected to one or more of the stator windings  62 . Busbar  64  may include a number of internal connections (not shown) that establish a wiring scheme for stator  58 . For example, plurality of electrically conductive members  72  may be connected to establish a wye or a delta connection for stator  58 . Towards that end, the number of first ends  78  may be different from the number of second ends  80  of the plurality of electrically conductive members  72 . 
     In an embodiment, insulating cover  74  includes a first wall  85  and a second wall  87  that are separated by a gap or groove  90  as shown in  FIG. 6 . Groove  90  provides an interface to a bracket  94  that connects busbar  64  to stator core  60 . As shown in  FIGS. 4 and 5 , bracket  94  is formed from a metal material and includes a base portion  98  mounted to stator core  60 . Base portion  98  may be welded to stator core  60  or secured through, for example, mechanical fasteners. A first tab member  104  and a second tab member  106  extend from a first end (not separately labeled) of base portion  98 . A third tab member  108  and a fourth tab member  110  extends from an opposing end of base portion  98 . 
     First tab member  104  includes a first radially outwardly facing side  113  and a second opposing or radially inwardly facing side  114 . Similarly, second tab member  106  includes a first radially outwardly facing side portion  116  and a second opposing or radially inwardly facing side portion  118 . Second side  114  includes a first protrusion  120  and first side portion  116  includes a second protrusion  122 . As shown in  FIG. 6 , first protrusion  120  acts upon first wall  85 . In a similar manner, second protrusion  122  acts upon second wall  87  to secure busbar  64  to bracket  94 . It should be understood that third and fourth tab members  108  and  110  are similarly formed. Bracket  94  also includes a support member  128  that provides mechanical support for busbar  64 . With this arrangement, busbar  64  provides a robust connection point for stator windings that may withstand vibrations and the like. 
     A busbar  134 , in accordance with another aspect of an exemplary embodiment, is shown in  FIG. 7 . Busbar  134  includes a plurality of electrically conductive members  136  surrounded by an insulating cover  138 . Insulating cover  138  may also surround a number of internal connections (not shown) that establish a selected connection scheme for stator  58 . Insulating cover  138  is mounted to a bracket  144  formed from a metal material having a first or base portion  146  and a second or support portion  148 . Base portion  146  is mounted to an outer surface (not separately labeled) of stator core  60 . Base portion  146  may be welded, brazed, or secured to the outer surface by fasteners (not shown). In one exemplary aspect, insulating cover  138  may be secured to support portion  148  through mechanical fasteners  152 . In another exemplary aspect, insulating cover  138  may be secured to support portion  148  by heat stakes  156  as shown in  FIG. 8 . 
     Reference will now follow to  FIGS. 9 and 10  in describing a busbar  166  in accordance with another exemplary aspect. Busbar  166  includes a plurality of electrically conductive members  170  that may be supported in an insulating cover  173 . Insulating cover  173  may support a number of internal connections of stator windings  62  to establish a selected wiring configuration. Plurality of electrically conductive members  170  include a plurality of terminal end portions  178  that interface with a terminal block  182  in housing  14 . 
     Busbar  166  is connected to a bracket  188  that is coupled to stator core  60 . In an embodiment, bracket  188  is formed from a metal material and includes a first or base portion  190  and a second or support portion  192 . Support portion  192  may provide an interface for a protective cover (not shown). Base portion  190  includes a first mounting element  197  and a second mounting element  198  that are connected to first and second mounting ears  199  and  200  of stator core  60  through mechanical fasteners  202  and  204 . Bracket  188  provides a robust attachment port for busbar  166  that reduces strain on terminal end portions  178 . 
     Reference will now follow to  FIGS. 11-13  in describing a busbar  205  in accordance with another exemplary aspect. Busbar  205  includes a plurality of electrically conductive members  206  supported by an insulating cover  208 . Insulating cover  208  may support a number of internal connections of stator windings  62  to establish a selected wiring configuration. Busbar  204  is mounted to a bracket  210  that is cantilevered from housing  14 . Bracket  210  is formed from a metal material and includes a first portion  212  that is connected to busbar  205  and a second portion  214  that is connected to housing  14 . First portion  212  includes a plurality of tab elements  217  that extend axially outwardly of stator core  60 . Second portion  214  includes mounting ears, one of which is indicated at  218 , coupled to housing  14  through mechanical fasteners (not separately labeled). 
     Insulating cover  208  includes a plurality of pockets  220  that are receptive of tab elements  217 . Insulating cover  208  may be joined to tab elements  217  through an adhesive, mechanical fasteners, staking, or, may be over-molded onto tab elements  217 . Second portion  214  is mounted to housing  14  adjacent a terminal block  228  including a plurality of connecting pads  230 . Connecting pads  230  may be coupled to terminal ends  232  of electrically conductive members  206 . In this manner, terminal block provides an electrical interface with stator winding  62 . Bracket  210  provides a robust attachment port for busbar  205  that reduces strain on terminal ends  232 . 
     The terms “about” and “substantially” are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” and/or “substantially” can include a range of ±8% or 5%, or 2% of a given value. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.