Abstract:
A bus bar assembly includes a deformable bus bar including a bus bar positive terminal flange, a bus bar negative terminal flange spaced-apart from the bus bar positive terminal flange and a flange connecting portion connecting the bus bar positive terminal flange and the bus bar negative terminal flange. A deformable bus bar frame includes a bus bar frame positive terminal flange carried by the bus bar positive terminal flange of the deformable bus bar and a bus bar frame negative terminal flange carried by the bus bar negative terminal flange of the deformable bus bar. A method of installing a deformable bus bar on positive and negative terminals of a battery cell is also disclosed.

Description:
FIELD 
       [0001]    Illustrative embodiments of the disclosure generally relate to electrical bus bars for electric vehicles (EVs). More particularly, illustrative embodiments of the disclosure relate to a deformable bus bar assembly and a bus bar installation method which compensate for differences in height between adjacent terminals on an HV battery. 
       BACKGROUND 
       [0002]    Bus bars for HV (hybrid vehicle) battery arrays may be attached via studs on the battery cells. Nuts may be threaded and tightened on the studs to form a strong, electrically-conductive joint. The studs may be used to locate the bus bars in the correct location for contact of the bus bars with the cell terminal on the battery cell. 
         [0003]    In some applications, it may be desirable to attach the bus bars to the cell terminals on the battery cell via welding. However, there may be differences in height between the positive and negative terminals on the battery cell. This may leave gaps between the bus bars and the terminals, compromising the integrity of the welds which secure the bus bars to the cell terminals. 
         [0004]    Accordingly, a deformable bus bar assembly and a bus bar installation method which compensate for differences in height between adjacent terminals on an HV battery may be desirable. 
       SUMMARY 
       [0005]    Illustrative embodiments of the disclosure are generally directed to a deformable bus bar assembly which compensates for differences in height between adjacent terminals on an HV battery. An illustrative embodiment of the bus bar assembly includes a deformable bus bar having a bus bar positive terminal flange, a bus bar negative terminal flange spaced-apart from the bus bar positive terminal flange and a flange connecting portion connecting the bus bar positive terminal flange and the bus bar negative terminal flange. A bus bar frame includes a bus bar frame positive terminal flange carried by the bus bar positive terminal flange of the deformable bus bar and a bus bar frame negative terminal flange carried by the bus bar negative terminal flange of the deformable bus bar. 
         [0006]    Illustrative embodiments of the disclosure are further generally directed to a method of installing a deformable bus bar on positive and negative terminals of a battery cell. An illustrative embodiment of the method includes placing spaced-apart bus bar positive and negative terminal flanges of a deformable bus bar on the positive and negative terminals, respectively, of the battery cell; and applying pressure against one of the bus bar positive and negative terminal flanges of the deformable bus bar to deform the deformable bus bar until the one of the bus bar positive and negative terminal flanges contacts a corresponding one of the positive and negative terminals, respectively, of the battery cell. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Illustrative embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0008]      FIG. 1  is a perspective view of an exemplary deformable bus bar; 
           [0009]      FIG. 2  is a front view of an illustrative embodiment of a deformable bus bar assembly having the exemplary deformable bus bar illustrated in  FIG. 1 ; 
           [0010]      FIG. 3  is a front view of the illustrative deformable bus bar assembly clamped onto a positive terminal and a negative terminal of a battery cell, with an electrode gap initially existing between the negative terminal and the deformable bus bar due to a difference in height between the positive terminal and the negative terminal in installation of the deformable bus bar; 
           [0011]      FIG. 4  is a front view of an illustrative deformable bus bar assembly with the deformable bus bar deformed to accommodate the difference in height between the positive terminal and the negative terminal; and 
           [0012]      FIG. 5  is a flow diagram of an illustrative embodiment of a deformable bus bar installation method. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable users skilled in the art to practice the disclosure and are not intended to limit the scope of the claims. Moreover, the illustrative embodiments described herein are not exhaustive and embodiments or implementations other than those which are described herein and which fall within the scope of the appended claims are possible. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
         [0014]    Referring initially to  FIGS. 1 and 2 , an exemplary deformable bus bar  1  ( FIG. 1 ) which is suitable for an illustrative embodiment of a deformable bus bar assembly  10  ( FIG. 2 ) is shown. The deformable bus bar  1  may include any suitable flexible or deformable and electrically conductive material. The deformable bus bar  1  may include a bus bar body  2 . In some embodiments, the bus bar body  2  may be generally elongated and rectangular with a pair of parallel longitudinal body edges  2   a ,  2   b , respectively, and transverse body edges  2   c  extending between the longitudinal body edges  2   a ,  2   b . A bus bar positive terminal flange  3  and a bus bar negative terminal flange  4  extend from the bus bar body  2  in spaced-apart relationship to each other along the longitudinal body edge  2   b . A bus bar slot  5  may extend between the bus bar positive terminal flange  3  and the bus bar negative terminal flange  4 . A flange connecting portion  6  may connect the bus bar positive terminal flange  3  and the bus bar negative terminal flange  4  between the bus bar slot  5  and the bus bar body  2 . 
         [0015]    As shown in  FIG. 2 , in exemplary application, which will be hereinafter described, the deformable bus bar  1  may be included as part of the deformable bus bar assembly  10 . The deformable bus bar assembly  10  may include a deformable bus bar frame  11  which may be plastic or other deformable material. The bus bar frame  11  may include a bus bar frame positive terminal flange  12  and a bus bar frame negative terminal flange  13 . A bus bar frame flange connector  14  may connect the bus bar frame positive terminal flange  12  and the bus bar frame negative terminal flange  13 . A bus bar flange slot  15  may separate the bus bar frame positive terminal flange  12  and the bus bar frame negative terminal flange  13  at the bus bar frame flange connector  14 . Accordingly, the bus bar frame positive terminal flange  12  and the bus bar frame negative terminal flange  13  of the bus bar frame  11  may rest on the bus bar positive terminal flange  3  and the bus bar negative terminal flange  4 , respectively, of the deformable bus bar  1 , with the bus bar slot  5  of the deformable bus bar  1  registering with the bus bar frame flange slot  15  of the bus bar frame  11 . 
         [0016]    Referring next to  FIGS. 3 and 4 , in exemplary application of the deformable bus bar  1 , the deformable bus bar assembly  10  is placed on a battery cell  18  of an HV vehicle. The battery cell  18  may be a conventional battery cell which is used to provide a source of electrical power to an EV (Electric Vehicle). The battery cell  18  may have a positive terminal  20  and a negative terminal  22  which are offset from each other, or different in height. The bus bar positive terminal flange  3  of the deformable bus bar  1  engages the positive terminal  20  of the battery cell  18 . However, due to the difference in height between the positive terminal  20  and the negative terminal  22  of the battery cell  18 , a contact gap  32  exists between the bus bar negative terminal flange  4  of the deformable bus bar  1  and the negative terminal  22  of the battery cell  18 . A positive terminal clamp finger  26  and a negative terminal clamp finger  28  may secure the deformable bus bar assembly  10  on the positive terminal  20  and the negative terminal  22  of the battery cell  18  as is known by those skilled in the art. 
         [0017]    As illustrated in  FIG. 4 , the negative terminal clamp finger  28  is tightened to progressively deform the bus bar frame negative terminal flange  13  at the bus bar frame flange connector  14  of the bus bar frame  11  and the underlying bus bar negative terminal flange  4  at the bus bar slot  5  and flange connecting portion  6  of the deformable bus bar  1 . Therefore, the bus bar negative terminal flange  4  and the bus bar frame negative terminal flange  13  traverse the contact gap  32  ( FIG. 3 ) until the bus bar negative terminal flange  4  makes solid contact or engagement with the negative terminal  22  of the battery cell  18 . The bus bar positive terminal flange  3  and the bus bar negative terminal flange  4  can then be welded to the positive terminal  20  and the negative terminal  22 , respectively. 
         [0018]    It will be appreciated by those skilled in the art that the deformable bus bar  1  can be deformed to compensate for the difference in height between adjacent terminals on a battery cell responsive to application of pressure to the deformable bus bar. Compared to conventional bus bars, the deformable bus bar may result in significant reduction or elimination of a contact gap between the bus bar and the positive or negative terminal on a battery cell. Because the deformable bus bar requires substantially less clamp force which is necessary to be applied for deformation to reduce or eliminate the contact gap, the total pressure which is necessary to be applied on the battery array or pack during the welding operation is substantially reduced. This expedient may reduce the risk of damaging the battery array or pack due to overload forces. In addition, the flexibility of this busbar lowers any peel or sheer forces seen on the welds due to any movement of the cells after welding. These movements could be caused by handling of the battery cell array after welding assembly into the battery pack, and during life of the battery pack in the vehicle. 
         [0019]    Referring next to  FIG. 5 , a flow diagram  500  of an illustrative embodiment of a deformable bus bar installation method is shown. At block  102 , a bus bar positive terminal flange and a bus bar negative terminal flange of a deformable bus bar are placed on positive and negative terminals, respectively, of a battery cell. A bus bar slot extends between the bus bar positive terminal flange and the bus bar negative terminal flange. A contact gap exists between the bus bar positive terminal flange and the positive terminal and the bus bar negative terminal flange and the negative terminal. 
         [0020]    At block  104 , pressure is applied against the bus bar positive terminal flange or the bus bar negative terminal flange of the deformable bus bar. In some embodiments, a bus bar frame may be placed on the deformable bus bar and the pressure may be applied to the bus bar frame. The deformable bus bar deforms at the bus bar slot until the bus bar positive terminal flange or the bus bar negative terminal flange traverses the contact gap and makes solid contact with the corresponding positive terminal or negative terminal, respectively. At block  106 , the bus bar positive terminal flange and the bus bar negative terminal flange of the deformable bus bar may be welded to the positive and negative terminals, respectively, of the battery cell. 
         [0021]    Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.