Patent Publication Number: US-2022240371-A1

Title: System and method for providing an electrical ground connection for a circuit assembly

Description:
TECHNICAL FIELD 
     The following relates to a system and method for providing an electrical ground connection for a circuit assembly. 
     BACKGROUND 
     Automotive vehicles having high voltage (HV) batteries, such as electric vehicles (EV) and hybrid electric vehicles (HEV), may include battery monitoring systems (BMS) to monitor and/or improve performance the HV batteries. In that regard, a BMS is an electronic unit that is inserted by the automotive original equipment manufacturer (OEM) inside a housing for an EV or HEV HV battery as part of a vehicle HV battery system, which may include battery cells, a cooling system, and battery cell monitoring electronics. 
     The BMS of a HV battery system requires a good connection to the vehicle ground (GND), such as the chassis of the vehicle. Indeed, such a ground connection may be required by various electronic assemblies or electronic arrangements that may be used throughout any type of vehicle, which electronic assemblies or electronic arrangements may include and/or comprise circuit assemblies, printed circuit boards (PCB), fuse boxes, controllers, modules, units, systems, or any other type of electronic assembly or electronic arrangement. 
     In that regard, compact and/or restrictive requirements may govern the placement of a HV battery system in an EV or HEV. Such compact and/or restrictive placement requirements for a HV battery system may include and/or affect the vehicle ground connection needed by a BMS. Similar design constraints and/or requirements may likewise include and/or affect the ground connection needed by any other type of electronic assembly or electronic arrangement used in a vehicle. As a result, a need exists for an improved system and method for providing an electrical ground connection for a circuit assembly, such as may be included in a BMS for a HV battery system for an EV or HEV. 
     SUMMARY 
     According to one non-limiting exemplary embodiment described herein, a system for providing an electrical ground connection for a circuit assembly is provided. The system may comprise a housing for the circuit assembly, the housing having an electrically conductive fixation member configured for attachment to an electrically conductive element outside the housing. The system may further comprise an electrically conductive feature having a first end and a second end, the first end configured to cooperate with the electrically conductive fixation member inside the housing and the second end configured for attachment to the circuit assembly. Attachment of the electrically conductive fixation member to the electrically conductive element outside the housing enables an electrical ground connection for the circuit assembly via the electrically conductive feature. 
     According to another non-limiting exemplary embodiment described herein, a system for providing an electrical ground connection for a circuit assembly is provided. The system may comprise an electrically conductive fixation member having a first portion configured to extend inside a housing for the circuit assembly and a second portion configured to extend outside the housing, the second portion further configured for attachment to an electrically conductive element. The system may further comprise an electrically conductive feature having a first end and a second end, the first end configured to cooperate with the first portion of the electrically conductive fixation member inside the housing and the second end configured for attachment to the circuit assembly. Attachment of the second portion of the electrically conductive fixation member to the electrically conductive element outside the housing enables an electrical ground connection for the circuit assembly via the electrically conductive feature. 
     According to yet another non-limiting exemplary embodiment described herein, a method for providing an electrical ground connection for a circuit assembly is provided. The method may comprise attaching a first end of an electrically conductive feature to a first portion of an electrically conductive fixation member, wherein the first portion of the electrically conductive fixation member is configured to extend inside a housing for the circuit assembly, and wherein the electrically conductive feature comprises (i) a conductive paint on a surface of the housing for the circuit assembly, (ii) a busbar, (iii) a wire, or (iii) a conductive mesh. The method may further comprise installing the circuit assembly into the housing, and attaching a second end of the electrically conductive feature to the circuit assembly. 
     A detailed description of these and other non-limiting exemplary embodiments of a system and method for providing an electrical ground connection for a circuit assembly is set forth below together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  are perspective views of a battery monitoring system module for use in a high-voltage battery housing of an electric or hybrid electric vehicle; 
         FIG. 2  is a cross-sectional view of the battery monitoring system module of  FIG. 1A , taken along the line  2 - 2 ; 
         FIG. 3  is a perspective view of an alternative battery monitoring system module including a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure; 
         FIGS. 4A and 4B  are a lateral cross-sectional views of the alternative battery monitory system module of  FIG. 3  taken along line  4 - 4  thereof, including a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure; 
         FIGS. 5A and 5B  are perspective views of exemplary electrically conductive features for the alternative battery monitory system module of  FIG. 3  including a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure; and 
         FIGS. 6A and 6B  are cross-sectional and perspective views, respectively, of exemplary electrically conductive fixation members for the alternative battery monitory system module of  FIG. 3  including a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed non-limiting embodiments are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary and may take various and alternative forms. The figures are not necessarily to scale, and features may be exaggerated or minimized to show details of particular components, elements, features, items, members, parts, portions, or the like. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art. 
     With reference to the Figures, a more detailed description of non-limiting exemplary embodiments of a system and method for providing an electrical ground connection for a circuit assembly will be provided. For ease of illustration and to facilitate understanding, like reference numerals may be used herein for like components and features throughout the drawings. 
     As previously described, compact and/or restrictive placement requirements for a HV battery system in an EV or HEV may include and/or affect the vehicle ground connection needed by a BMS. Similar design constraints and/or requirements may likewise include and/or affect the ground connection needed by any other type of electronic assembly or electronic arrangement used in a vehicle. As a result, a need exists for an improved system and method for providing an electrical ground connection for a circuit assembly, such as may be included in a BMS for a HV battery system for an EV or HEV. 
     In that regard,  FIGS. 1A-1C  illustrate perspective views of a module for a battery monitoring system (BMS) for use in a high voltage (HV) battery housing of an electric vehicle (EV) or hybrid electric vehicle (HEV), where the HV battery housing is not size-restricted. As seen therein, according to the configuration and/or design shown, the BMS module  10  may be inserted in a housing  12  for a HV battery. The BMS module  10  may include mounting or fixation features  14 , which may include electrically conductive tabs having apertures formed therein. The mounting/fixation features  14  are accessible after insertion of the BMS module  10  into the HV battery housing  12 . As a result, using the mounting/fixation features  14 , the BMS module  10  may be screwed into the bottom chassis plate of the HV battery housing  12 . The BMS module  10  may also be provided with a horizontally oriented electrical connector  16  on one side or a side surface thereof, and the HV battery housing  12  may be provided with a lateral opening  18  through which the electrical connector  16  may extend when the BMS module  10  is mounted to the HV battery housing  12 . 
       FIG. 2  illustrates a cross-sectional view of the BMS module  10  of  FIG. 1A , taken along the line  2 - 2 . As seen therein, the electrically conductive mounting/fixation features  14  of the BMS module  10  may be connected or attached to a printed circuit board (PCB) of the BMS module  10 . As a result, fixation or attachment of the BMS module  10  to the HV battery housing  12  (see  FIG. 1B ) using screws (not shown) inserted through the apertures formed in the mounting/fixation features  14  also provides a robust electrical ground connection for the BMS module  10 , as the HV battery housing  12  (see  FIG. 1B ) is electrically conductive. 
     Referring now to  FIG. 3 , a perspective view is shown of an alternative design for a BMS module  10 ′ including a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure. As seen therein, the alternative design for the BMS module  10 ′ may include one or more fixation features  22  provided on a bottom surface or side of the BMS module  10 ′. Such fixation features  22  may be configured for cooperation with features provided on a bottom chassis surface a HV battery housing  12 ′, such as by a snap-in or a snap-on like operation, to thereby mount or attach the BMS module  10 ′ to the HV battery housing  12 ′ in an efficient and effective manner. Such features  22  are used because there is no space for a tool (at the OEM assembly line) that would fix screws in position. Alternative, a snap-in or snap-on like operations may not be required, but only centering, in which case the BMS will only be fixed to the top cover. Such features  22  and fixation are described in greater detail in co-pending U.S. patent application Ser. No. 16/674,593, entitled “System And Method For Mounting An Electronics Arrangement,” filed on Nov. 5, 2019, the disclosure of which is hereby incorporated herein by reference in its entirety. 
     As also seen in  FIG. 3 , the alternative design of the BMS module  10 ′ may include a vertically oriented electrical connector  16 ′ provided on a top side or top surface thereof. The previously described fixation of the BMS module  10 ′ to the HV battery housing  12 ′ may be blind, and the BMS module  10 ′ may also be provided with one or more fixation members  24  on a top side or top surface thereof. In that regard, fixation members  24 , which may comprise threaded bolts or screws, may be configured to attach or fix the BMS module  10 ′ to a top cover of the HV battery housing  12 ′ (see  FIG. 4B ). 
     Thus, the BMS module  10  shown in  FIGS. 1A-1C and 2  has a physical and electrical connection to a bottom plate or surface of the HV battery housing  12 . The BMS module  10  may be fixed to the HV battery housing  12  because the fixation points are accessible for screwing after the BMS module  10  has been inserted in place in the HV battery housing  12 . 
     In contrast, the BMS module  10 ′ shown in  FIG. 3  has a blind mechanical fixation, or location, or initial placement position to an interior surface of the HV battery housing  12 ′ via the non-conductive (e.g., plastic) fixation (or location or initial placement position) features  22  of the housing of the BMS module  10 ′. Because the housing of the BMS module  10 ′, including the fixation (or location or initial placement position) features  22 , are non-conductive (e.g., plastic), only the external fixation members  24  (e.g., threaded bolts or screws) configured for attaching the BMS module  10 ′ to a top surface or cover of the HV battery housing  12 ′ are available for establishing a ground connection for the BMS module  10 ′. In that regard, one or more of the fixation members  24  may be electrically conductive and, as a result, may also be used to connect the BMS module  10 ′ to an electrically conductive element outside the housing of the BMS module  10 ′ and thereby establish, enable, create, provide, or complete an electrical ground connection or path, either directly or indirectly through the HV battery housing  12 ′, as will be further described herein. 
       FIGS. 4A and 4B  are lateral cross-sectional views of the alternative BMS module  10 ′ of  FIG. 3  taken along line  4 - 4  thereof, illustrating a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure. As seen therein, the electrical connector  16 ′ of the BMS module  10 ′ may include or comprise a pin header  26  having a plurality of pins. The pin header  26  may be configured for attachment to a printed circuit board (PCB)  20 ′ of the BMS module  10 ′, which PCB  20 ′ may include or have mounted thereon or therein any type or number of electrical or electronic components for use in monitoring a HV battery for an EV or HEV. In that regard, the electrical connector  16 ′, the pin header  26 , the PCB  20 ′, and any of the electrical or electronic components previously described may comprise, be referred to as, constitute, or include an electric, electrical, or electronic circuit or circuit assembly. 
     The BMS module  10 ′ may also include or comprise an electrically conductive feature which may comprise one or more busbars  28 .  FIGS. 5A and 5B  are perspective views of exemplary electrically conductive features  28  for the alternative battery monitory system module of  FIG. 3  including a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure. As seen therein, and with continuing reference to  FIGS. 4A and 4B , each busbar  28  may extend in a plurality of planes and may have a first end, such as tab  30 , which may be configured for attachment to the electrically conductive fixation member  24  inside the housing of the BMS module  10 ′. The housing of the BMS module  10 ′ may also include positioning or placement elements or features (not shown) to facilitate correct positioning of the busbar  28  in place. 
     In that regard,  FIGS. 6A and 6B  are cross-sectional and perspective views, respectively, of exemplary electrically conductive fixation members  24  for the alternative battery monitory system module of  FIG. 3  including a system and method for providing a ground connection for a circuit assembly according to one non-limiting exemplary embodiment of the present disclosure. As seen therein, and with continuing reference to  FIGS. 4A, 4B, 5A, and 5B , the electrically conductive fixation member  24  may comprise a first portion  34  configured to extend inside the housing of the BMS module  10 ′. The first portion  34  of the electrically conductive fixation member  24  and the first tab  30  of the busbar  28  may be configured for attachment by an adhesive or a weld. Alternatively, the first portion  34  of the electrically conductive fixation member  24  may have a threaded recess  36  formed therein configured to receive a screw  38  and the first tab  30  of the busbar  28  may have an opening  40  formed therein configured to receive the screw  38 . The housing of the BMS module  10 ′ may also include positioning or placement elements or features (not shown) to facilitate correct positioning or placement of the busbar and to prevent rotation of the busbar while the screw  38  is being fixed inside the recess  36  of fixation member  24 . 
     Referring still to  FIGS. 4A, 4B, 5A, and 5B , each busbar  28  may also have a second end, such as tab  32 , which may be configured for attachment to the circuit assembly or PCB  20 ′. More specifically, the second tab  32  of the busbar  28  may have an opening  42  formed therein configured to receive a screw  44  and the circuit assembly or PCB  20 ′ may have an opening formed therein (not shown) configured to receive the screw  44  for attachment of the second tab  32  of the busbar  28  to the PCB  20 ′. In that regard, the busbar  28  may be fixed or attached in such a fashion to an electrical ground of the PCB  20 ′, which may take the form of or comprise an island, trace, point, layer, or component of the PCB  20 ′. It should also be noted that the screw  44  may also be used to fix the PCB  20 ′ in place, thus avoiding the need to use an extra screw for that connection to ground. Alternatively, the second end or tab  32  of the busbar  28  may be shaped, configured, or include a feature (not shown) for direct fixation into the PCB, such as by surface or through hole soldering, or as a press-fit terminal. 
     According to the system and method of the present disclosure, the busbar(s)  28  may be used to establish, enable, create, provide, or complete a ground connection from a vehicle chassis (not shown) to an electrical ground of the PCB  20 ′ through the electrically conductive fixation members  24 . In that regard, still referring to  FIGS. 4A, 4B, 6A, and 6B , the fixation members  24  may be overmolded in the non-conductive (e.g., plastic) housing of the BMS module  10 ′. A portion  46  of the fixation member(s)  24  may extend outside the housing of the BMS module  10 ′, thereby providing for or enabling both electrical and mechanical fixation of the BMS module  10 ′ to an electrically conductive element or electrical ground terminal or electrical ground path outside the housing of the BMS module  10 ′, such as the electrically conductive cover of the HV battery housing  12 ′. Such overmolding of the fixation members  24  in the plastic housing of the BMS module  10 ′ may leave the portion  34  of the fixation members  24  accessible for contact with or attachment to the busbar  28 . As shown, each of the fixation members  24  may have a first portion  34  configured to extend and/or be exposed inside the housing of the BMS module  10 ′ and, as previously described, configured for attachment to the busbar  28 . 
     The top portion or cover of the HV battery housing  12 ′ may have an aperture formed therein configured to receive the vertically oriented electrical connector  16 ′ of the BMS module  10 ′. The cover of the HV battery housing  12 ′ may also have apertures  56  formed therein configured to receive the second portion  46  of the fixation members  24 , which second portion  46  may be configured to extend outside the housing of the BMS module  10 ′. The electrically conductive fixation members  24  may also be provided with a surface or shoulder configured to contact the electrically conductive HV battery housing  12 ′ and thereby ensure robust electrical contact and conductivity between the fixation member  24  and the HV battery housing  12 ′. 
     As previously described, the fixation members  24  may comprise a bolt or screw having a threaded portion  48 . One or more threaded nuts (not shown) may be provided and/or configured for mechanical (e.g., screwed) and/or electrical fixation or attachment of the HV battery housing  12 ′ to the fixation members  24 . The electrical ground connection path established (see  FIG. 4B ) may be described as follows: GND of PCB  20 ′→busbar  28 →fixation member  24 →cover of HV-battery housing  12 ′→vehicle chassis (GND) (not shown). A water-tight sealing member  50 , such as a rubber or silicon gasket, may also be provided between a cover of the HV battery housing  12 ′ and a top cover of the housing of the BMS module  10 ′. The purpose of such sealing is to avoid water (liquid) ingress into the HV battery system. The sealing member  50  may be provided with a “lip” to close the cover of the HV battery housing  12 ′ with the exterior surface of the cover of the BMS module  10 ′. The sealing member  50  may also be provided with another “lip” surrounding each of the fixation members  24  to ensure no ingress of water (liquid) into the BMS module  10 ′ through a protruding fixation member  24  (i.e., between bolts  24  and the surrounding plastic). The screw-bolt fixation also compresses the sealing member  50  to ensure that it seals properly. To ensure connection mechanical torque and electrical contact, no gasket is provided between the bolt, cover, nut fixation. In that regard, as the nut (not shown) is metallic, it is also in electrical contact. 
     It should also be noted that the fixation members  24  may also be provided or configured with an extension  52  which may serve or act as an aid for centering the apertures  56  formed in the HV battery housing  12 ′ with the fixation members  24 . As previously described, the electrically conductive fixation member  24  may be overmolded in the housing of the BMS module  10 ′. In that regard, the electrically conductive fixation member  24  may comprises an anti-rotation feature  54  configured to resist rotation of the electrically conductive fixation member  24  in the housing of the BMS module  10 ′ during rotation of the nut (not shown) on the threaded shaft  48  of the electrically conductive fixation member  24 . As seen in  FIG. 6B , such an anti-rotation feature  54  of the fixation member  24  may take the form of a head having a multi-faceted or multi-faced (i.e., non-circular) circumference, although any know type of anti-rotation feature may alternatively be provided. 
     The system and method of the present disclosure thus provide attachment of the second portion  46  of the electrically conductive fixation member  24  to the electrically conductive element  12 ′ outside the housing of the BMS module  10 ′, thereby enabling an electrical ground connection for the circuit assembly  20 ′ via the electrically conductive feature comprising the busbar  28 . The system and method of the present disclosure thus provide direct connection of an electronic circuit to a vehicle chassis (GND) in an efficient fashion, thereby simplifying installation, assembly, and/or manufacturing as well as minimizing cost. 
     Thus, the present disclosure provides a system and method for providing an electrical ground connection for a circuit assembly. According to the system and method of the present disclosure, the first tab  30  of the electrically conductive feature  28  may be attached to the first portion  34  of the electrically conductive fixation member  24 . In that regard, the electrically conductive feature  28  may comprise a busbar extending in a plurality of planes and the first portion  34  of the electrically conductive fixation member  24  may be configured to extend inside the housing of the BMS module  10 ′ for the circuit assembly or PCB  20 ′. According to the system and method of the present disclosure, the circuit assembly or PCB  20 ′ may be installed into the housing of the BMS module  10 ′, and the second tab  32  of the electrically conductive feature comprising the busbar  28  may be attached to the circuit assembly or PCB  20 ′. The PCB  20 ′ may then be enclosed with a bottom portion of the housing of the BMS module  10 ′. 
     As previously described, the electrically conductive fixation member  24  may comprise a second portion  46  configured to extend outside the housing of the BMS module  10 ′ for attachment to the electrically conductive element  12 ′. In that regard, the second portion  46  of the electrically conductive fixation member  24  may be attached to the electrically conductive element  12 ′ outside the housing of the BMS module  10 ′ to provide an electrical ground connection for the circuit assembly or PCB  20 ′ via the electrically conductive feature comprising the busbar  28 . 
     As also previously described, the first portion  34  of the electrically conductive fixation member  24  may have a threaded recess  36  formed therein configured to receive a screw  38  and the first tab  30  of the busbar  28  may have an opening  40  formed therein configured to receive the screw  38 . Attaching the first tab  30  of the electrically conductive feature comprising the busbar  28  to the first portion  34  of the electrically conductive fixation member  24  may therefore comprise screwing the first tab  30  of the busbar  28  to the first portion  34  of the electrically conductive fixation member  24 . Moreover, the electrically conductive fixation member  24  may be overmolded in the housing of the BMS module  10 ′. It should also be noted that, as an alternative to the connection of the busbar  28  to the fixation member  24  described previously, the busbar  28  may also be overmolded into the housing of the BMS module  10 ′. In such an embodiment, because robustness may be provided by the housing plastic, instead of a busbar, the electrically conductive feature  28  may alternatively comprise a thinner connection element, such as a wire, a conductive mesh, or a conductive painted (or the like) path. It should also be noted that the busbar  28  may take the form of a member extending from (and which may be integral with) the fixation member  24 . Thus, the first end  30  of the busbar  28  may be configured to cooperate with the first portion  34  of the fixation member  24 , such as by integrally extending from the first portion  34  of the fixation member  24  or by being configured to be attached, connected, or joined to or with the first portion  34  of the fixation member  24  as previously described herein. The busbar  28  may also have an extension (not shown) at the second end  32 , which may be rod-like, which extends downward and is configured to fit into or otherwise cooperate with a hole formed in the PCB  20 ′ to provide for attachment of the busbar  28  to the PCB  20 ′, such as by a screw or by a soldered or press-fit connection. 
     Once assembled, the BMS module  10 ′ may be inserted into and fixed to the bottom portion or base of the HV battery housing  12 ′, such as by fixation features  22 . The top portion or cover of the HV battery housing  12 ′ may be attached to the BMS module  10 ′ in a closure operation using the fixation members  24  formed in and extending outside the housing of the BMS module  10 ′. The fixation members  24  may be received by cooperating apertures  56  formed in the cover of the HV battery housing  12 ′, which may be secured to the BMS module  10 ′ using nut(s) (not shown). A ground connection to the circuit assembly may be completed, created, established, enabled, or provided by integration of the HV battery housing  12 ′ into a vehicle, such as an EV or HEV. 
     The present disclosure thus describes an improved system and method for providing an electrical ground connection for a circuit assembly, such as may be included in a BMS for a HV battery system for an EV or HEV. In that regard, the HV battery system environment or application described in connection with the system and method for providing an electrical ground connection for a circuit assembly of the present disclosure is exemplary only and the system and method of the present disclosure may be used in other environments or applications. The system and method for providing an electrical ground connection for a circuit assembly described herein overcome, address, solve, or mitigate compact and/or restrictive placement requirements for a HV battery system in an EV or HEV that may include and/or affect the vehicle ground connection needed by a BMS. The system and method for providing an electrical ground connection for a circuit assembly described herein also overcome, address, solve, or mitigate similar design constraints and/or requirements that may likewise include and/or affect the ground connection needed by any other type of electronic assembly or electronic arrangement used in a vehicle. 
     As is readily apparent from the foregoing, various non-limiting embodiments of a system and method for providing an electrical ground connection for a circuit assembly have been described. While various embodiments have been illustrated and described herein, they are exemplary only and it is not intended that these embodiments illustrate and describe all those possible. Instead, the words used herein are words of description rather than limitation, and it is understood that various changes may be made to these embodiments without departing from the spirit and scope of the following claims.