Patent Publication Number: US-10780767-B2

Title: System for absorbing and distributing side impact energy utilizing an integrated battery pack

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present U.S. Utility Patent Application claims priority pursuant to 35 U.S.C. § 120 as a continuation of U.S. Utility application Ser. No. 14/703,646, entitled “SYSTEM FOR ABSORBING AND DISTRIBUTING SIDE IMPACT ENERGY UTILIZING AN INTEGRATED BATTERY PACK”, filed May 4, 2015, which is a continuation of U.S. Utility application Ser. No. 14/168,351, entitled “SYSTEM FOR ABSORBING AND DISTRIBUTING SIDE IMPACT ENERGY UTILIZING AN INTEGRATED BATTERY PACK,” filed Jan. 30, 2014, now U.S. Pat. No. 9,045,030 issued on Jun. 2, 2015, which is a continuation of U.S. Utility application Ser. No. 13/308,300, entitled “SYSTEM FOR ABSORBING AND DISTRIBUTING SIDE IMPACT ENERGY UTILIZING AN INTEGRATED BATTERY PACK,” filed Nov. 30, 2011, now abandoned, which claims priority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Application No. 61/426,254, entitled “BATTERY PACK STRUCTURES AND CONFIGURATIONS FOR AN ELECTRIC VEHICLE,” filed Dec. 22, 2010, all of which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility Patent Application for all purposes. 
    
    
     BACKGROUND 
     Modern vehicles use a variety of structures to protect the vehicle&#39;s occupants during a crash. Some of these structures are used to control the transmission of the crash energy to the passenger compartment while other structures, such as seat belts, head restraints, and air bags, are intended to restrain passenger movement during a crash, thereby preventing the passengers from hurting themselves as their bodies react to the crash forces. Side impact collisions present a particularly challenging problem to vehicle safety engineers, both due to the relatively low position of the rocker panels on many small vehicles as well as the difficulty of implementing an impact resistant side structure while taking into account vehicle doors and doorways. 
     U.S. Pat. No. 6,676,200, issued 13 Jan. 2004, discloses an automotive structure utilizing inner and outer rocker panels, a floor pan joined to the inner rocker panels, and a plurality of cross-members that extend laterally across a portion of the vehicle body. The cross-members include energy absorbing extensions designed to absorb side impact loads. 
     An alternate approach to achieving impact resistance is disclosed in U.S. Pat. No. 6,793,274, issued 21 Sep. 2004, in which an energy management system is integrated within various automotive structural components, e.g., vehicle frames and rails. In particular, the disclosed system uses members or inserts that are in some way attached to selected structural components of the vehicle, the members designed to both absorb and redirect the impact energy encountered during a crash. The disclosed members also help to reinforce the components to which they are attached. The patent describes a variety of ways in which the disclosed members may be incorporated into a vehicle during the manufacturing process. 
     U.S. Pat. No. 7,090,293, issued 15 Aug. 2006, attempts to achieve improved occupant protection through a seat assembly that is designed to provide side impact rigidity and resistance to rocker override and side impact intrusions. The disclosed seat assembly includes a frame track, a frame base slidably engaged to the frame track, a frame back rotatably engaged to the frame base, and a rear lateral support assembly that includes a support frame attached to the rear portion of the frame base. The support frame includes a tubular member that is designed to engage with a vehicle rocker panel during impact, thereby providing additional rigidity and strength to the vehicle. 
     U.S. Pat. No. 8,007,032, issued 30 Aug. 2011, discloses an automotive energy absorbing side structure that includes a wide-based B-pillar with an internal reinforcing tube, a rocker with an internal bulkhead, a rear rocker, and at least one cross-member extending inward from the rocker. The disclosed cross-members are designed to transfer impact loads to the floor, the cross-members and the tunnel brace. 
     Although vehicle manufacturers use a variety of structures and components to protect a vehicle&#39;s occupants during a side impact collision, typically these approaches provide only limited protection while significantly increasing vehicle weight. Accordingly, what is needed is a system that provides superior vehicle occupant safety, particularly from side impact collisions, while adding minimal weight from impact resistant dedicated structures. The present disclosure provides such a system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  provides a simplified bottom view of an electric vehicle with a battery pack incorporated into the vehicle structure; 
         FIG. 2  provides a perspective view of a vehicle&#39;s undercarriage with the battery pack incorporated into the vehicle structure; 
         FIG. 3  provides a perspective view of a portion of a vehicle body and frame with the battery pack separated from the structure; 
         FIG. 4  provides a perspective view of the battery pack shown in  FIGS. 1-3 ; 
         FIG. 5  provides a perspective view of the battery pack shown in  FIGS. 1-4 , with the top panel removed; 
         FIG. 6  provides a perspective view of the battery pack shown in  FIGS. 1-5 , this view showing three of the battery modules in place within the pack; 
         FIG. 7  provides a perspective, cross-sectional view of the battery pack shown in  FIGS. 1-6  mounted under the floor panel of the vehicle shown in  FIG. 3 ; 
         FIG. 8  provides a detailed cross-sectional view of one of the cross-members shown in  FIG. 7 ; 
         FIG. 9  provides a detailed cross-sectional view of an alternate cross-member; 
         FIG. 10  provides a detailed cross-sectional view of an alternate cross-member; 
         FIG. 11  provides a detailed cross-sectional view of an alternate cross-member; 
         FIG. 12  provides a perspective view of the battery pack to rocker panel assembly; 
         FIG. 13  provides a cross-sectional view of the assembly shown in  FIG. 12 ; 
         FIG. 14  provides a cross-sectional view of a structural support element; 
         FIG. 15  illustrates the sculpted leading edge of the battery pack in accordance with the disclosure; 
         FIG. 16  provides a perspective view of a sub-frame mount integrated into the battery pack; 
         FIG. 17  provides an alternate view of the sub-frame mount shown in  FIG. 16 ; 
         FIG. 18  illustrates a vehicle frontal impact system utilizing the battery pack; 
         FIG. 19  provides a side view of the frontal impact system shown in  FIG. 18 ; 
         FIG. 20  illustrates the use of the battery pack to enhance the rigidity of the steering rack mount; 
         FIG. 21  provides an alternate view from that shown in  FIG. 20 ; and 
         FIG. 22  provides a cross-sectional view of a seat mounting structure mechanically coupled to the battery pack using structure from  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following text, the terms “battery”, “cell”, and “battery cell” may be used interchangeably and may refer to any of a variety of different cell types, chemistries and configurations including, but not limited to, lithium ion (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickel zinc, silver zinc, or other battery type/configuration. The term “battery pack” as used herein refers to multiple individual batteries contained within a single piece or multi-piece housing, the individual batteries electrically interconnected to achieve the desired voltage and capacity for a particular application. The term “electric vehicle” as used herein refers to either an all-electric vehicle, also referred to as an EV, plug-in hybrid vehicles, also referred to as a PHEV, or a hybrid vehicle (HEV), a hybrid vehicle utilizing multiple propulsion sources one of which is an electric drive system. 
     The present disclosure integrates a battery pack into an electric vehicle in order to add rigidity to the vehicle structure and significantly increase the vehicle&#39;s side impact resistance by absorbing and distributing the impact load throughout the battery pack structure. To achieve the desired level of structural rigidity, strength and impact resistance, preferably the battery pack is large relative to the overall dimensions of the vehicle and includes multiple cross-members as described in detail below. In a preferred embodiment of the disclosure illustrated in  FIGS. 1-3 , battery pack  101  not only transverses the width of the vehicle, i.e., from rocker panel to rocker panel, but also extends most of the distance between the front suspension  103  and the rear suspension  105 . It will be appreciated that while smaller battery packs may be used with the disclosure, they may not provide the same level of side impact protection, depending upon their size and the number of integrated cross-members. In the illustrated embodiment, battery pack  101  is approximately 2.7 meters long and 1.5 meters wide. The thickness of battery pack  101  varies from approximately 0.1 meters to 0.18 meters, the thicker dimension applicable to those portions of the battery pack in which battery modules are positioned one on top of another, as described further below. 
       FIG. 4  provides a perspective view of battery pack  101  with the top enclosure panel  401  in place, panel  401  preferably providing a substantially airtight seal. Hollow side structural elements  403  are also visible, members  403  preferably including an extended region or lip  405  that is used to mechanically and thermally couple the side members  403  to the vehicle structure (not shown in this figure).  FIG. 5  shows battery pack  101  with top member  401  removed, this view showing cross-members  501 A- 501 H. The number of cross-members is based on the number of cells/cell modules that are to be encased within the battery pack as well as the desired structural characteristics of the battery pack. Preferably battery pack side members  403 , including extended region  405 , battery pack top panel  401  and battery pack bottom panel  505  are each fabricated from a light weight metal, such as aluminum or an aluminum alloy, although other materials such as steel may be used for some or all of the battery pack components. Bottom panel  505  may be welded, brazed, soldered, bonded or otherwise attached to side members  403 , with the resultant joint between panel  505  and member  403  preferably being substantially air-tight as well as being strong enough to allow bottom panel  505  to support the batteries contained within the pack. Top panel  401  is typically attached to member  403  using bolts or similar means, thus simplifying battery replacement as well as allowing battery interconnects, battery pack components, cooling system components and other battery pack components to be repaired and/or replaced. 
     Cross-members  501 A- 501 H provide several benefits. First and foremost relative to side impact resistance, members  501 A- 501 H provide mechanical and structural strength and rigidity to the battery pack and to the vehicle to which the battery pack is attached. Additionally, cross-members  501 A- 501 H help to segregate thermal events by providing a thermal barrier between groups of cells as well as minimizing gas flow between sections  503 , sections  503  being defined by the cross-members, side members  403 , top member  401  and bottom member  505 . By segregating thermal events within smaller groups of cells, thermal runaway propagation is limited as is the potential for battery pack damage. 
       FIG. 6  shows a similar view to that provided by  FIG. 5 , with the inclusion of a couple of cell modules  601 . In this illustration, a single module  601  is shown positioned within one of the seven, larger sections  503  of battery pack  101 . Note that each large section  503  is designed to house a pair of battery pack modules  601 . Additionally, in this illustration there are two modules  601  stacked one on top of the other in the front section  507  of pack  101 . Note that in the preferred embodiment, each module  601  contains 370 individual cells, each cell utilizing an 18650 form factor. It should be understood, however, that this configuration is only exemplary of a preferred embodiment and that the disclosure is equally applicable to other configurations, for example utilizing batteries with a different form factor, a larger or smaller number of cells, individual cells versus modules, etc. 
       FIG. 7  provides a perspective, cross-sectional view of battery pack  101  mounted under floor panel  701  of vehicle  100 . This view also provides additional views of the cross-members. As shown by the cross-sectional view, in the preferred embodiment cross-members  501 A- 501 H do not utilize the same cross-section; rather the cross-section of each is optimized for each member&#39;s location within the pack. In general, cross-members  501 A- 501 H may either be comprised of a single unit or, as preferred and illustrated, comprised of an upper member and a lower member. One or both members may be hollow, thus achieving the desired rigidity and strength while minimizing weight. It should be understood that not only can the configuration/design of the cross-members vary, depending upon their location within the pack, so can the materials comprising the cross-members. Therefore while cross-members  501 A- 501 H are preferably fabricated from aluminum or an aluminum alloy, for example using an extrusion process, other materials (e.g., steel, ceramics, etc.) may also be used if such materials fit both the mechanical and thermal goals for the particular cross-member in question. Additionally, the lumens within one or more of the cross-members may be unfilled or filled with a high melting temperature, low thermal conductivity material (e.g., fiberglass or similar materials). Alternately, the lumens within the cross-members may include a liquid (e.g., water), the liquid being either stagnant or flowing. If stagnant, the liquid may be contained within the lumens themselves or, as preferred, contained within pouches that fit within the cavities. If the liquid is flowing, it is preferably contained within tubing that is inserted within the cross-member cavities and either coupled to a battery cooling system or used in a stand-alone circulation system. 
     In the preferred embodiment, and as illustrated in  FIG. 7 , cross-members  501 D and  501 E are larger than the other central cross-members. The reason for the increased size is to provide additional cross-member strength at those locations that are most critical to achieving the desired level of side-impact resistance. As shown in the detailed cross-sectional view of  FIG. 8 , in the preferred embodiment cross-members  501 D and  501 E are comprised of an upper member  801  that is attached to battery pack top panel  401  and includes a single lumen  803 , and a lower member  805  that is attached to battery pack bottom panel  505  and includes a pair of lumens  807  and  809 . In this embodiment, member  801  is approximately 19 millimeters high, 30 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Member  805  is approximately 54 millimeters high, 26 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. 
     Cross-members  501 B,  501 C,  501 F and  510 G are slightly smaller than cross-members  501 D and  501 E, although they retain the basic shape of the larger cross-members. As shown in the detailed cross-sectional view of  FIG. 9 , these cross-members are comprised of an upper member  901  that is attached to battery pack top panel  401  and includes a single lumen  903 , and a lower member  905  that is attached to battery pack bottom panel  505  and includes a pair of lumens  907  and  909 . In this embodiment, member  901  is approximately 19 millimeters high, 16 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Member  905  is approximately 54 millimeters high, 16 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Note that the spacing between upper member  801  and lower member  805 , and the spacing between upper member  901  and lower member  905 , is used in the preferred embodiment to capture a battery module mounting bracket (not shown in  FIGS. 8 and 9 ). 
     Cross-member  501 A, located near the rear of battery pack  101  and illustrated in the detailed cross-section of  FIG. 10 , includes a first member  1001  that extends from battery pack lower panel  505  to battery pack top panel  401 . Member  1001  is comprised of a large lower section  1003  and a small upper section  1005  with respective lumens  1007  and  1009 . Section  1003  of member  1001  is approximately 54 millimeters high, 30 millimeters wide, and has a wall thickness of between approximately 2 and 4 millimeters. Section  1005  of member  1001  is approximately 29 millimeters high, 13 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Cross-member  501 A also includes a second member  1011  that includes a single lumen  1013  as shown. Member  1011  is approximately 29 millimeters high, 16 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. 
     Cross-member  501 H shown in the detailed view of  FIG. 11 , is located near the front of battery pack  101  and between battery pack section  507  and the adjacent section  503 . As section  507  is designed to house two battery pack modules, one on top of the other, this portion of battery pack  101  utilizes a different design which, in turn, affects the design of cross-member  501 H. As shown, cross-member  501 H includes an upper member  1101  that has a single lumen  1103 , and a lower member  1105  that has a single lumen  1107 . Member  1101  is approximately 54 millimeters high, 26 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Member  1105  is approximately 29 millimeters high, 26 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. 
       FIGS. 12 and 13  provide perspective and cross-sectional views, respectively, that illustrate the attachment of the battery pack  101  to vehicle structural side member  1201 . In the preferred embodiment structural side member  1201  is comprised of a rocker panel, also referred to herein as a sill, which is formed from extruded aluminum or an aluminum alloy (although other materials such as steel may be used for members  1201 ). Preferably a seal or gasket is located between the top surface  1301  of side members  403  and the bottom surface  1303  of the top panel  401 , thus achieving a substantially air-tight seal. An o-ring groove  1304  is visible in  FIG. 13  for use with such a seal. In the illustrated embodiment, each side member  403  includes four lumens  1305 - 1308 . Lower exterior lumen  1308  is positioned under the extended region  405  of side member  403 . Lumen  1308  is perforated on upper surface  1309  and lower surface  1311 , the perforations on these two surfaces being aligned such that bolts  1313 , or similar means, may pass completely through lumen  1308 , thereby allowing bolts  1313  to couple extended region  405  of member  403  to structural side member  1201  as shown. Bolts  1313  and channel nuts  1315  securely attach side members  403 , and therefore battery pack  101 , to the vehicle&#39;s structural members  1201 . Preferably channel nuts  1315  are held in place during assembly using channel nut retainer  1317 . In addition to providing a strong mechanical coupling, this approach allows battery pack  101  to be quickly and efficiently removed from underneath vehicle. 
       FIG. 14  provides a cross-sectional view of a structural support element  1400 . A bolt  1402  penetrates a metallic sleeve  1404  that is welded to the structure. Bolt  1402  threads through a nut  1406 , for example in a cross-member of the vehicle structure. This interface is then sealed at multiple interfaces when the bolt is tightened and provides additional clamping force to the battery mounts. Here, spacing between an upper member  1408  and a lower member  1410  is used to capture a battery module mounting bracket  1412 . 
       FIG. 22  provides a cross-sectional view of a seat mounting structure mechanically coupled to the battery pack using structure from  FIG. 14 . In some implementations, a battery pack is used for facilitating through-bolting seat mountings. A seat mounting structure  2200  is mechanically coupled to the battery pack on the opposite side of vehicle floor  1403  by connecting seat mounting structure  2200  to bolt  1402  using nut  1406 . Coupling the seat mounting structure  2200 , and thus the vehicle seats (not shown, but attached via threaded seat mount  2202 ), to the battery pack provides greatly enhanced seat mount performance. As shown, the vehicle has a cross-member (i.e., structure  2200 ) with a threaded sleeve  2202  welded into it which provides the mount which the seat sits on top of and bolts into. From the opposing side and in close proximity to (as illustrated) or coaxially with the seat mount, a bolt  1402  penetrates a metallic sleeve  1404  that is welded to the structure. Bolt  1402  threads through the nut  1406  which is contained in the cross-member  2200  in the vehicle structure. This interface is then sealed at multiple interfaces when the bolt is tightened and provides additional clamping force to the battery mounts. 
       FIG. 15  illustrates the sculpted leading edge of the battery pack in accordance with the disclosure. In some implementations, a battery enclosure has an aerodynamic form. In accordance with at least one aspect of the disclosure, the battery pack of a vehicle is used as an aerodynamic device for improving the vehicle&#39;s overall aerodynamic performance. In a preferred embodiment, the bottom surface of the battery pack is flat, or substantially flat, and the front wheel arch edges are heavily radiused in order to allow air from the wheel wells to transition from the slow moving wheel arch edges to the underside of the vehicle.  FIG. 5  illustrates this aspect of the disclosure, showing a sculpted leading edge  1500  of the battery pack, thereby creating an aerodynamic shape between the front wheel arch and the flat bottom of the pack. This design aids the purging of air from within the wheel arch. Note that sculpted front wheel arch edge  501  is also visible in  FIGS. 1-3 . 
       FIG. 16  provides a perspective view of a sub-frame mount integrated into the battery pack.  FIG. 17  provides an alternate view of the sub-frame mount shown in  FIG. 16 . In some implementations, a sub-frame mount is integrated into a battery pack. The purpose of a rubber sub-frame bushing is to isolate the passenger compartment from the road inputs as well as to tune the overall dynamics of the suspension. The ability to tune the sub-frame bushing to act predictably in all cases is dependent on the rigidity of its mounting to the vehicle. By mounting a bushing using one mount surface and a bolt, the bolt and mount location is highly loaded in single shear. By adding an extra attachment to another component, this loading can be distributed among additional members and the mounting becomes stiffer. This in turn increases the performance of the bushing by allowing it to be more precisely tuned. In accordance with the disclosure, and as illustrated in  FIGS. 16 and 17 , this goal is achieved by mounting the sub-frame bushing in double shear with a piece of structure  1600  that is attached directly to the bottom plate of the battery enclosure. It will be appreciated that structure  1600  may either be separate from the bottom panel  607  of battery pack  601  and designed to be bolted to panel  607 , or it may be fabricated as an integral part of the battery pack enclosure. Preferably this aspect of the disclosure is combined with a coaxial double screw fixture, thereby allowing the battery pack and sub-frame structure  1600  to be removed from the vehicle while retaining the sub-frame bushing attachment to the body-structure. 
       FIG. 18  illustrates a vehicle frontal impact system utilizing the battery pack.  FIG. 19  provides a side view of the frontal impact system shown in  FIG. 18 . In some implementations, a battery pack is used in a frontal impact system. In a conventional hybrid or electric vehicle, the battery pack is isolated and not used as a load bearing member that contributes to frontal impact performance. In the present disclosure, however, the battery pack is made strong enough to resist forces from the front of the vehicle. Additionally, the battery pack strengthens the overall ability of the front torque boxes to distribute frontal loads into the sills of the vehicle. Accordingly, in another aspect of the disclosure, battery pack  601  is used as an integral part of the load path used for the management of loads in a frontal impact to protect the occupants during such an event. Preferably, and as shown in  FIGS. 18 and 19 , the majority of the loads are fed from the rails into the front torque box. The buckling stability and strength of this torque box is significantly increased by coupling the battery box in four locations to this structural member. In addition, a secondary load path feeds loads from the lower portion of the vehicle along the sub-frame and into the rear mount of the sub-frame that is coupled to the battery and the torque box using a single bolt. This allows the loads from a frontal impact to not only be input into the torque boxes, but into the battery. The battery then feeds the loads along its members to the sill sections of the vehicle and also stabilizes the torque boxes in this mode. 
       FIG. 20  illustrates the use of the battery pack to enhance the rigidity of the steering rack mount.  FIG. 21  provides an alternate view from that shown in  FIG. 20 . In some implementations, the battery pack is used to enhance steering feel. The rigidity of the steering rack mounting is integral to providing high quality steering feel, response, and feedback from the road to the driver. In accordance with another aspect of the disclosure, and as illustrated in  FIGS. 18 and 19 , the structure of the battery pack, and more specifically the thick bottom plate of the battery pack, is used to provide exemplary shear stiffness in the y direction to the mounting locations of the steering rack in order to provide a more rigid and direct connection of the steering rack to the vehicle structure in order to resist opposite loads input from the road. 
     In a conventional vehicle, it is difficult to achieve the desired rigidity in the steering rack mounting without adding extra material, and therefore mass. In accordance with the disclosure, however, the shear stiffness of the bottom panel of the existing battery pack structure is used to stiffen the point at which the steering rack is mounted. By using a structure already present in the vehicle, the efficiency of the mounting is improved by coupling these components without the added mass which would be necessary to stiffen the steering rack mounting in a conventional configuration. 
     In some implementations, mounting the battery pack to the body structure provides a stiffness multiplier effect. In accordance with another aspect of the disclosure, the battery pack is designed to add not just its own stiffness but a multiple of it to the vehicle&#39;s body structure. This multiplier effect has been achieved through the manner in which the pack is mounted as well as the design of the pack which, in particular, is not designed to possess maximum stiffness in its own right, but to intentionally penalize that for the greater benefit of when it is attached to the body structure. This is achieved by balancing the relative thicknesses of the battery pack structure. To achieve the multiplier effect, the structure of the battery pack has been deliberately compromised as a stand-alone item for significantly greater contribution when attached to the body structure. That the pack contributes not just its own stiffness but nearly three times that when attached is of considerable benefit and saves vehicle weight and increases range. 
     It should be understood that identical element symbols used on multiple figures refer to the same component, or components of equal functionality. Additionally, the accompanying figures are only meant to illustrate, not limit, the scope of the disclosure and should not be considered to be to scale. 
     Systems and methods have been described in general terms as an aid to understanding details of the disclosure. In some instances, well-known structures, materials, and/or operations have not been specifically shown or described in detail to avoid obscuring aspects of the disclosure. In other instances, specific details have been given in order to provide a thorough understanding of the disclosure. One skilled in the relevant art will recognize that the disclosure may be embodied in other specific forms, for example to adapt to a particular system or apparatus or situation or material or component, without departing from the spirit or essential characteristics thereof. Therefore the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the disclosure which is set forth in the following claims.