Abstract:
Battery packs are retained by frames which are comprised of plastic beams and aluminum corner connectors that peripherally surround the battery packs. The plastic beams are tension by tensioning bolts which pass through the aluminum corner connectors and thread into threaded pin inserts laterally seated in the beams. As the tensioning bolts are advanced into the inserts the beams are axially tensioned. Damping pads are disposed between the separate battery modules of the battery packs, as well as at the corners of the frames, to both absorb vibrational and spike impacts. The damping pads frictionally engage the outer surfaces of the battery cases so that the batteries will not move in the Z-axis direction, thus minimizing the risk that battery interconnections will be damaged. The frames rest on a supporting surface, such as the surfaces of a battery pack tray. The bottoms of the battery modules are spaced from the tray so that the battery packs are vertically supported by the frames only around the peripheries of the battery packs.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention is directed to battery pack arrangements. More particularly, the present invention is directed to battery pack arrangements used in EV/HEV vehicles.  
       BACKGROUND OF THE INVENTION  
       [0002]     Electric vehicles (EV) and hybrid electric vehicles (HEV) use battery packs comprised of several individual storage batteries that provide current to propel the vehicles and operate vehicle accessories. In at least one configuration, the modules are in two layers with a lower layer received in a generally rectangular case, and an upper layer positioned on a tray above the lower layer. A cover encloses the upper layer and is latched to the case. In order to stabilize the battery packs within the case and cover, the battery packs must be both laterally and vertically supported. This is usually accomplished by a compressive force applied to the top surfaces of the battery packs. Some designs stabilize the battery packs using a cover-pad-tray retention arrangement, while others utilize a rigid skeleton.  
         [0003]     There is a need to minimize, at minimal cost, relative motion between battery modules within battery packs in order to reduce or eliminate interconnection failures that may occur within battery packs. As EVs and HEVs evolve, there is also a need to provide arrangements which allow for changes in design so that battery pack configurations may be more readily altered to accommodate vehicle design considerations.  
       SUMMARY OF THE INVENTION  
       [0004]     In view of the aforementioned considerations, the present invention is directed to an arrangement for stabilizing in electric or hybrid electric vehicles at least one rectangular battery pack that includes an array of separate battery modules, wherein the battery pack has four side surfaces, a bottom surface and a top surface. The arrangement comprises a rectangular frame having four beams with each beam engaging one of the four sides of the battery pack. Four corner connectors are disposed at the ends of each beam to couple at right angles one beam to another. Tensioners are provided for positively connecting each corner connector to two beams. The tensioners draw the beams toward the corner connectors in order to clamp the battery modules in the battery pack against one another.  
         [0005]     In still a further aspect of the invention, the beams each engage one of the four sides of the battery pack at a location spaced from the bottom surface of the battery pack, with a portion of each beam extending beneath the bottom surface of the battery pack, to support the battery pack adjacent to the periphery thereof on a supporting surface.  
         [0006]     In a further aspect of the invention, damping pads are positioned between the battery modules of the battery pack.  
         [0007]     In still a further aspect of the invention, the corner connectors are unitary bodies, each having a first pair of holes opening in directions normal to one another for receiving threaded fasteners therethrough. Axially extending threaded holes are provided in the beams to threadably receive the threaded fasteners to draw the beams toward the corner connectors as the threaded fasteners are rotated.  
         [0008]     In a preferred embodiment, the threaded fasteners are threaded bolts and the threaded axial holes are in anchors disposed in the beams.  
         [0009]     In a further aspect of the invention, the beams are made of plastic and the corner connectors of metal.  
         [0010]     In still a further aspect of the invention, the frame is connected to a tray by fasteners.  
         [0011]     In still a further aspect of the invention there are plural battery packs mounted on a single tray with each battery pack stabilized by a peripheral frame.  
         [0012]     In still a further aspect of the invention, there is a middle frame flanked by two side frames. The middle frame has two beams which rest on two beams of the side frames. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:  
         [0014]      FIG. 1  is a top perspective view of EV/HEV battery pack arrangement configured according to the principles of the present invention;  
         [0015]      FIG. 2  is a bottom perspective view of the battery pack arrangement of  FIG. 1 ;  
         [0016]      FIG. 3  is a perspective view of a single battery module which is assembled with other batteries to configure the battery pack arrangements of  FIGS. 1 and 2 ;  
         [0017]      FIG. 4  is a perspective view of a framing arrangement used with the battery pack arrangement of  FIGS. 1 and 2 ;  
         [0018]      FIG. 5  is a schematic view of forces applied to a battery pack tray by the battery pack framing arrangement of  FIGS. 1 and 2 ;  
         [0019]      FIG. 6  is an exploded view of framing arrangement employed in  FIGS. 1 and 2 ;  
         [0020]      FIG. 7  is a perspective view of a portion of an intermediate frame used in the framing arrangement of  FIG. 4 , and  
         [0021]      FIG. 8  is an exploded perspective view of a portion of the framing arrangement of  FIG. 4 . 
     
    
     DETAILED DESCRIPTION  
       [0022]     Referring now mainly to  FIGS. 1 and 2 , a battery pack arrangement  20 , configured in accordance with the present invention, is shown disposed on a tray  25  which provides a supporting surface  26  for the battery pack arrangement. The supporting surface  26  could also be provided by frame (not shown) that could be anchored to or be part of automotive vehicle structure.  
         [0023]     A retention system  30  retains an inner battery pack  32  positioned between a first outer battery pack  34  and a second outer battery pack  36 . In the illustrated embodiment, each of the battery packs  32 ,  34  and  36  includes five separate battery modules  37 . Each of the battery packs  32 ,  34  and  36  has four sides  40 ,  41 ,  42  and  43 , as well as a top surface  44  and a bottom surface  45 .  
         [0024]     As is seen in  FIG. 3 , each individual battery module  37  has a pair of long side surfaces  50  and  51  and a pair of short end surfaces  52  and  53 , as well as a top surface  54  and bottom surface  55 .  
         [0025]     The battery pack arrangement  20  comprised of the battery packs  32 ,  34  and  36  utilizes a frame arrangement  60  shown separate from the battery packs in  FIG. 4 . The frame arrangement  60  is comprised of a middle frame  62 , a first side frame  64  and a second side frame  66 . As is best seen in the bottom view of  FIG. 2 , the two side frames  64  and  66  have bottom surfaces  68  and  70  which project beyond the bottom surfaces  45  of the battery packs  32 ,  34  and  36 . Consequently, when the battery pack arrangement  20  rests on the tray  25  ( FIG. 1 ), only the bottom surfaces  68  and  70  of the frame arrangement  60  abut the tray. This leaves the bottom surfaces  45  of each of the battery packs  32 ,  34  and  36 , and thus the bottom surfaces  55  of each individual battery module  37 , spaced from the tray  25 . As is best seen in  FIG. 2 , the bottom surface  69  of frame  62  that is disposed around the middle battery pack  32  is preferably spaced from the bottom surface  45  of the middle battery pack  32 . This keeps the top surfaces of all three battery packs at the same height from the surface  26  tray  25 . As a result, pressure on the surface  26 , as illustrated in  FIG. 5  by the arrows  72 , has a pressure distribution only at perimeters  74  and  75  of the battery packs  34  and  36 .  
         [0026]     From  FIG. 5  it is seen that the weight of the individual battery modules  37  has been transferred laterally through side surfaces  50  and  51  and the end surfaces  52  and  53  of the individual battery modules  37  to the frames  62 ,  64  and  66 . Note from  FIGS. 1 and 2  that the bottom surface  69  of the frame  62  retaining the middle battery pack  32  rests on the top surfaces of frames  64  and  66  so the middle battery pack  32  does not itself directly engage the surface  26  of the tray  25 .  
         [0027]     The pressure pattern of  FIG. 5  is further understood upon considering the structure of the frame arrangement  60  shown assembled in  FIG. 4  and exploded in  FIGS. 6, 7  and  8 . As is seen in  FIG. 4 , the middle frame  62  has four beams  81 ,  82 ,  83  and  84 , which are joined by four corner connectors  85 ,  86 ,  87  and  88  that are adjustable with respect to the beams. The beams  81 - 84  are preferably made of plastic, but may be made of metal or any other suitable material that may be tensioned. The corner connectors  85 - 88  are preferably made of a metal, such as aluminum or an aluminum alloy, but may be made of any other suitable, relatively rigid material. Bolt holes  90  extend downwardly through the beams  82  and  84  for anchoring the beams of the middle frame  62  with respect to the tray  25 . The bolt holes  90  in beams  82  and  84  align with similar bolt holes in the frames  64  and  66  so that bolts  92  pass through into or through the frames  64  and  66 .  
         [0028]     The frames  64  and  66  which retain the outer battery packs  34  and  36  are substantially similar in configuration, each including four beams  101 ,  102 ,  103  and  104  and four corner connectors  105 ,  106 ,  107  and  108 . As with the middle frame  62 , the beams  101 - 104  of the outer frames  64  and  66  are preferably made of plastic, but may be made of other materials, such as metal, or any other suitable material which is tensionable. Like the previously discussed corner connectors  85 - 88 , the corner connectors  105 - 108  are also preferably made of a metal such as aluminum or an aluminum alloy, but may be made of other suitable materials. The beams  102  of the frames  64  and  66  may be clamped to the tray  25  of  FIG. 1  or may be bolted to the tray. The beams  101  and  103 , as well as the beams  104  may also be bolted to the tray  25 . If the tray is not structurally substantial enough to itself to support the battery pack arrangement  20 , the tray  25  has structural elements associated therewith to secure the beams  101 - 104 . The beams  101  and  103  of the frames  64  and  66  may also be secure to the tray  25  by clamping or bolts. The frames  64  and  66  each have pairs of shallow U-shaped brackets  110  and  112  projecting from the beams  101  and  103  to which other structures such as covers (not shown) are attached via holes  113  therethrough.  
         [0029]     As will be further explained hereinafter, each of the sets of side beams  81 - 84  and  101 - 104  are tensioned by the associated corner connectors  85 - 88  and  105 - 108 , respectively. These tensionings squeeze the battery modules  37  together so that the sides surfaces  50  and  51  and end surfaces  52  and  53  of the battery casings form lateral supporting surfaces. In accordance with a preferred embodiment of the invention, L-shaped damping pads  120  ( FIGS. 6 and 8 ) are disposed adjacent to each of the corner connectors  85 - 88  and  105 - 108 . The L-shaped damping pads  120  bear against the beams  81 - 84  and  101 - 104  to provide relatively small pressure areas at the corners of the battery packs  32 ,  34  and  36  to urge the separate battery modules  37  of the battery packs  32 ,  34  and  36  laterally toward one another. Flat damping pads  122  are disposed between the exteriorly disposed batteries  37  of the battery packs  62 ,  64  and  66  and the interiorly disposed batteries  37  of the battery packs. Preferably, the flat damping pads  122  are positioned at the upper and lower corners of facing sides  50  and  51  of the battery modules  37 . The damping pads  120  and  122  absorb vibration, as well as prevent movement of the modules in the upward and downward (Z-axis) direction with respect to one another. The damping pads  120  and  122  are made of a non-slip material so as to provide sufficient friction force to eliminate movement in the Z-axis direction and have sufficient resiliency to absorb vibrational impacts as well as spike impacts. While any suitable material for the damping pads may be used, preferable materials for the damping pads are plastics, such as NYLON®, polyphenyl sufones or polydicyclopentadienes.  
         [0030]     Referring now to  FIG. 7 , where a portion of the frame  62  of the framing arrangement  60  is shown as an example, it is seen that two of the beams  82  and  83  are joined with a single corner connector  87 . The corner connector  87  is relatively rigid with a cavity  129  therein while the beams  82  and  83  are elongated, rigid and may be tensioned. This is accomplished by threaded tensioning bolts  130  and  132  which have heads  134  and  136  which bear against interior wall surfaces of the corner connector  87 . The tensioning bolts  130  and  132  have threaded shank portions  138  and  140  which are received in threaded bores  142  and  144  of retaining anchors  146  and  148  that are configured as pins inserted laterally into each of the beams  82  and  83 .  
         [0031]     Referring further just to  FIG. 7 , the beams  82  and  83  are telescoped with respect to the right angle portions  154  an  156  of the corner connector  87  in that the beams are mounted either into or of the right angle portions. Consequently, the beams  82  and  83  are pulled toward the corner connector  87  and tensioned with respect to the other adjacent corner connectors  88  and  86  shown in  FIGS. 4 and 6 . The corner connector  87  has a diagonal wall  158  with an oval opening  160  into the cavity  129  therein that provides access for a bit of a tool (not shown) which engages and rotates the tensioning bolts  130  and  132  to drive the bolts into the threaded openings  144  and  142  in the retaining anchors  146  and  148  so that the bolts serve as tensioners when rotated. The retaining pins  146  and  148  are prevented from rotation because they are seated in the lateral bores  150  and  152 . Spring biased plugs  164  and  166  keep the retaining anchors  146  and  148  properly aligned in the bores  150  and  152  so that the threaded holes  144  and  142  are oriented to receive the tensioning bolts  130  and  132 . The corner connectors  85 ,  86  and  88  are substantially similar to, and preferably identical to, the corner connector  87 . The tensioning bolts  130  and  132  of the corner connectors  85 - 88  are tightened after assembly of the frame  62  so that the frame  62  is drawn against the corner pads  120  (see  FIGS. 6 and 8 ) in the X-axis and Y-axis directions to peripherally squeeze the battery modules  37  of the battery pack  32  towards one another. This also compresses the damping pads  120  and  122  disposed between the individual battery modules  37  of the battery packs  32 ,  34  and  36  to keep the individual battery modules stationary with respect to one another in the vertical or Z-axis direction.  
         [0032]     As is seen in  FIG. 8 , the side frames  64  and  66  of the battery packs  34  and  36  are constructed and arranged in a substantially similar manner as the previously discussed middle frame  62 . Each of the corner connectors  105 - 108  of the side frames  64  and  66  is secured by tensioning bolts  130  and  132  threaded into openings in anchors, which bolts serve as tensioners  172  and  174  to draw the beams  101 - 104  toward the corner connectors  105 - 108  so that each of the beams is drawn in opposite directions along either the Y-axis or the X-axis. The corners  105 - 108  are preferably configured to telescope with respect to the beams  101 - 104  so that the beams are drawn either into or over the corners. Thus, just as with the beams  81 - 84  of the frame  62 , the beams  101 - 104  of the frames  64  and  66  peripherally tension around the battery packs  34  and  36 , causing the damping pads  120  to squeeze the individual battery modules  37  toward one another. As with the previously discussed frame  62 , compressing the damping pads  120  and  122  keeps the individual battery modules  37  from moving in the Z-axis direction due to frictional engagement of the damping pads with the side surfaces  50  and  51  of each of the battery modules.  
         [0033]     The frames  64  and  66  retaining the battery packs  34  and  36  have bottom surfaces  68  and  70  that are disposed beyond the bottom surfaces of the battery packs  34  and  36  which results in pressure distribution pattern of  FIG. 5 . This feature is in addition to the arrangement provided by the frame  62 , which in the illustrated embodiment of  FIG. 1 , does not project beyond the bottom surface  45  of the battery pack  32 .  
         [0034]     In the illustrated and preferred embodiment, there are three battery packs  32 ,  34  and  36  retained by separate frames  60 ,  62  and  64 . However, there may be a single battery pack with more or fewer battery modules  37  than the five batteries shown in each of the battery packs  32 ,  34  and  36 . Moreover, there may be framing arrangements with just two battery packs or framing arrangement with four or more battery packs, wherein the battery packs are nested together or separate.  
         [0035]     In the illustrated arrangement, where there are three battery packs  32 ,  34  and  36 , the frame  62  rests on the beams  104  of the adjacent frames  64  and  66  to save lateral space which would be the combined width of the two beams  104 . This arrangement permits ease of assembly and lateral flexibility as well as allowing air flow both beneath the middle battery pack  32  and in gaps between the middle battery pack  32  and the first and second side battery packs  34  and  36 . In addition, there is a relatively shallow space beneath the middle battery pack  32 , through which a wiring harness or piping may extend in order to provide further design flexibility for EVs and HEVs as the technology evolves.  
         [0036]     The battery pack retention system  30  of the present invention is relatively inexpensive and reliable while providing design flexibility by freeing battery pack retention structure from case and cover arrangements. This makes it easier to design and fabricate cases and covers for battery packs, because by using the present invention the cases, covers and trays primarily provide for environmental protection by isolating the battery modules from the surrounding environment. Consequently, low cost plastic may be used for the tray  25  and a cover (not shown) for the tray while thermoplastic material is used for the beams  81 - 84  and  101 - 104 . The corner pieces  85 - 88  may be made from aluminum or other strong materials. Utilization of plastic beams and aluminum corner pieces minimizes tolerance issues with respect to reliability retaining the battery modules  37 , as well as providing opportunities to use common parts in later designs and to apply effective manufacturing processes such as extrusion to make parts for mass production. Thus the battery pack arrangement  20  of  FIG. 1  for EVs/HEVs reduces overall cost, delivery time and weight without compromising quality.  
         [0037]     From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing form the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.