Battery support system

Abstract

A support system for an array of battery cells comprises first and second side rails (28),30 and a crossmember 26. The crossmember comprises a first member 20 having an elongate body and a projection

Description

TECHNICAL FIELD The present disclosure relates to a battery support system. Aspects of the invention relate to a battery support system, to a vehicle comprising a battery support system, to a method of assembling an apparatus for supporting an array of battery cells in a battery frame, and to an apparatus for supporting an array of battery cells in a battery frame. BACKGROUND Battery modules of a battery electric vehicle (BEV) are typically housed beneath the cabin floor, in a compartment between side rails of the battery frame. The battery module casings provide some protection and structural support to battery cells within the modules, and crossbeams (sometimes referred to as crossmembers) that extend between the side rails may provide additional lateral structural support. Battery arrangements that utilise a ‘cell-to-pack’ layout, in which the battery cells are not housed in conventional modules, provide a reduction in weight associated with the battery structures themselves, but do not afford the protection and structural support normally provided by the module casings. Furthermore, in a dual-tier ‘cell-to-pack’ layout formed of stacked upper and lower layers of battery cells, additional structural elements may be required to provide sufficient support to both layers of battery cells. Conventional crossbeams for supporting battery modules may not be suitable to meet such structural requirements. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a battery support system, a vehicle, a method and an apparatus as claimed in the appended claims. According to an aspect of the present invention there is provided a battery support system for supporting an array of battery cells. The battery support system comprises first and second side rails of a battery frame and a crossmember. The crossmember comprises a first member comprising an elongate first member body and a first member projection that extends laterally from the first member body in a direction that is substantially perpendicular to a longitudinal axis of the first member. The first member extends between and is attached to the first and second side rails of the battery frame such that the longitudinal axis of the first member is substantially perpendicular to a longitudinal axis of each of the first and second side rails. The crossmember comprises a second member comprising an elongate second member body and a second member projection that extends laterally from the second member body in a direction that is generally perpendicular to a longitudinal axis of the second member. The second member is vertically stacked on and attached to the first member such that the longitudinal axis of the second member is substantially parallel to the longitudinal axis of the first member, and the first and second member projections extend in substantially parallel planes to 1 define a first gap between them for receiving at least a portion of one or more battery cells of a first tier of the array. The battery support system advantageously provides lateral structure and support to battery cells housed in the battery frame, as well as contributing to overall battery stiffness. The first member advantageously provides a lateral load path that absorbs loads in preference to the battery cells of the array. Furthermore, lateral load can advantageously be dissipated via the side rails to which the first member is attached. In this way, battery cells can be incorporated in the vehicle without being housed in conventional modules that would normally provide structural support and protection, thus reducing the weight associated with the battery structures themselves. It will be appreciated that reduction of the weight of such vehicle components has a positive impact on energy requirements of the vehicle. The battery support system may comprise a third member that comprises an elongate third member body and a third member projection that extends laterally from the third member body in a direction that is substantially perpendicular to a longitudinal axis of the third member. The third member may be vertically stacked on and attached to the second member such that the longitudinal axis of the third member is substantially parallel to the longitudinal axes of the first and second members. The second and third member projections may extend in substantially parallel planes to define a second gap between them for receiving at least a portion of one or more battery cells of a second tier of the array. In this way, the battery support system can advantageously support a dual-tier array of battery cells. The battery support system may comprise first and second adaptors for attaching the first member to the first and second side rails. The first adaptor may be welded to the first side rail and the second adaptor may be welded to the second side rail. A first end of the first member may be welded to the first adaptor, and a second end of the first member may be welded to the second adaptor. Any means of permanent fixing may be employed instead of welding, although that is a convenient method. References herein to welding should therefore be understood to include other methods of permanent fixing components together. As will become clear, construction and assembly of the battery support system can initially be permanent, but once batter cells are installed, remaining fixation of components, that is assembly of the second and third members at least, needs to be capable of subsequent dismantling in the case of a need to service the arrangement, for example to replace any faulty battery cells. The adaptors advantageously couple the first member to the side rails, such that lateral loads through the first member are dissipated via the battery frame for enhanced protection of the battery cells. The first and third members may be substantially the same length as one another, and may extend substantially the full width between the first and second side rails. The second member may be shorter than the first and / or third member. This provides openings in the assembled crossmember, through which electronic and / or cooling apparatus associated with the battery cells may extend. The second member may be formed of a higher strength material than the first member to provide additional strength to the second member projection in particular. This is beneficial as the second member projection may be required to support the weight of an upper tier or layer of battery cells. The third member may be attached to the first and second side rails via the first and second adaptors. A first end of the third member may be bolted to the first adaptor and a second end of the third member may be bolted to the second adaptor. This allows lateral load absorbed by the third member to be dissipated via the side rails. It also permits the third member to be disassembled from the support system so that batteries in the upper tier or layer of battery cells can be accessed for servicing. Likewise, the second member may be bolted to the first member, whereby it may be disassembled from the support system so that batteries in the lower tier or layer of battery cells can also be accessed for servicing. While bolting is a convenient method, any method of temporarily securing components together may be employed instead of bolting. The third member may be formed of a higher strength material than the first member. This is particularly advantageous in embodiments in which the third member defines the primary lateral load path of the crossmember. The crossmember may comprise at least one opening configured to receive electronic or cooling apparatus extending between battery cells positioned on opposing sides of the crossmember. The at least one opening may be defined between the first and second members and / or the second and third members. This is advantageous to simplify the routing of electrical and cooling apparatus between opposing sides of the crossmember. The second member may be attached to the first member using adhesive and / or bolted connections. The third member may be attached to the second member using adhesive and / or bolted connections. The use of adhesive and / or bolted connections between the second and first members and the third and second members rather than welds, for example, is beneficial to ensure that any battery cells already assembled in the arrangement are not damaged (e.g. through high temperatures in their vicinity required by the welding process). The battery support system may be provided in combination with a first tier of battery cells located at least partially in the first gap and secured to the first and second projections, and a second tier of battery cells located at least partially in the second gap and secured to the second and third projections. The battery cells may be secured to the relevant projections using adhesive such as glue. A further first member projection, second member projection and third member projection may extend laterally from the respective member body to define first and second gaps for receiving battery cells along opposing sides of the crossmember. According to another aspect of the invention, there is provided a vehicle comprising the battery support system of any preceding paragraph. According to another aspect of the invention, there is provided a method of assembling an apparatus for supporting an array of battery cells in a battery frame, the apparatus comprising a first member and a second member, wherein the first member comprises an elongate first member body and a first member projection and the second member comprises an elongate second member body and a second member projection. The method comprises: attaching the first member to opposed first and second side rails of the battery frame such that the first member extends between the first and second side rails, and a longitudinal axis of the first member is substantially perpendicular to a longitudinal axis of each of the first and second side rails; securing a first tier of battery cells to the first member projection after attaching the first member to the first and second side rails; and vertically stacking the second member on top of the first member and attaching the second member to the first member after securing the first tier of battery cells to the first member projection, such that a longitudinal axis of the second member is substantially parallel to the longitudinal axis of the first member, the first and second member projections extend in substantially parallel planes, and at least a portion of each battery cell of the first tier is positioned in a first gap defined between the first and second member projections. Advantageously, the method provides for the assembly of unpackaged battery cells in a vehicle, in such a way that lateral load path can be dissipated through a crossmember and first and second side rails for protection of the battery cells. The method may comprise arranging a second tier of battery cells above the first tier of battery cells after attaching the second member to the first member, and securing the battery cells of the second tier to the second member projection. The method may comprise vertically stacking a third member comprising an elongate third member body and a third member projection on top of the second member and attaching the third memberto the second member after securing the second tier of battery cells to the second member projection, such that a longitudinal axis of the third member is substantially parallel to the longitudinal axes of the first and second members, the second and third member projections extend in substantially parallel planes, and at least a portion of each battery cell of the second tier is positioned in a second gap defined between the second and third member projections. The method may comprise attaching the first member to the first and second side rails by: welding a first adaptor to the first side rail; welding a second adaptor to the second side rail; welding a first end of the first memberto the first adaptor; and welding a second end of the first memberto the second adaptor. The method may comprise attaching the third memberto the first and second side rails by: bolting a first end of the first member to the first adaptor; and bolting a second end of the first memberto the second adaptor. In this way, the method of assembly accounts for the need to consider different joining I attachment methods at different stages of the process, due to the use of unpackaged battery cells that are not housed in conventional modules. The method appreciates that welding can be used to secure the first members and adaptors in place, because at this stage no battery cells are present. However, once battery cells 18 are arranged in the assembly, other attachment methods such as bolts and adhesive may be utilised instead to avoid damage to the battery cells. According to another aspect of the invention, there is provided an apparatus for supporting an array of battery cells in a battery frame comprising opposed first and second side rails. The apparatus comprises: a first member comprising an elongate first member body and a first member projection that extends laterally from the first member body in a direction that is substantially perpendicular to a longitudinal axis of the first member; and a second member comprising an elongate second member body and a second member projection that extends laterally from the second member body in a direction that is generally perpendicular to a longitudinal axis of the second member. In an assembled configuration of the apparatus: the first member extends between and is attached to the first and second side rails of the battery frame, such that the longitudinal axis of the first member is substantially perpendicular to a longitudinal axis of each of the first and second side rails; and the second member is vertically stacked on the first member such that the longitudinal axis of the second member is substantially parallel to the longitudinal axis of the first member, and the first and second member projections extend in substantially parallel planes to define a first gap between them for receiving at least a portion of one or more battery cells of a first tier of the array. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a vehicle comprising a battery support system; Figure 2 shows a perspective view of a crossbeam of a battery support system; Figure 3 shows a perspective view of a first member of the crossbeam of Figure 2; Figure 4 shows a perspective view of a second member of the crossbeam of Figure 2; Figure 5 shows a perspective view of a third member of the crossbeam of Figure 2; Figure 6 is a perspective view of an adaptor of the battery support system for attaching the crossbeam to a side rail of the battery support system; Figure 7 shows the connection between the third member of Figure 5 and the adaptor of Figure 6; Figure 8 is a cut-away end view of the crossbeam, showing the first, second and third members in a vertical stack and the adaptor of Figure 6; Figure 9 is a top plan view of four crossbeams and a row of battery cells assembled in a floor panel of a frame of the battery support system, between side rails of the frame; Figure 10 is a perspective view of two crossbeams and a dual-tier stack of battery cells arranged between them; Figure 11 is a side view of the crossbeam of Figure 2, showing pass-through openings for cooling and electronics; and Figure 12 is a side view of an alternative crossbeam, showing pass-through openings for cooling and electronics. DETAILED DESCRIPTION Figure 1 illustrates a vehicle 10 comprising a battery support system 12 in accordance with an embodiment of the present invention. As will be explained, the battery support system 12 supports an array of battery cells 18 in the vehicle 10 beneath the vehicle cabin 14. An embodiment of the battery support system 12 of the invention is illustrated in Figures 2 to 12. As shown in Figures 3 to 5, the battery support system 12 includes a first member 20, a second member 22 and a third member 24 that are vertically stacked to form a crossbeam 26 (also referred to as a crossmember) as shown in in part in Figure 2. The crossbeam 26 extends between first and second side rails 28, 30 of frame 32 (only one of which side rails is shown in Figure 2) to support an array of battery cells 18, as will be explained. Each of the first, second and third members 20, 22, 24 are formed of aluminium in this example, although it will be appreciated that it would be possible and appropriate to use other materials for one or more of the members 20, 22, 24 in other embodiments. The first member 20 is shown in isolation in Figure 3. The first member 20 is elongate and extends from a first end 34 to a second end 36 along a first longitudinal axis 38 and defining the full length 58 of the first member 20 (and crossbeam 26). The first member 20 comprises a first member body 40 having a generally rectangular cross-sectional profile, and a pair of first member projections or flanges 42. The first member body 40 comprises a lower wall 44, an intermediate wall 46 and an upper wall 48. Left and right side walls 50, 52 of the first member body 40 extend between and join the lower wall 44, the intermediate wall 46 and the upper wall 48. As such, the lower wall 44, the intermediate wall 46 and the upper wall 48 are vertically spaced from one another to define an upper chamber 54 and a lower chamber 56 in the first member body 40. The upper and lower chambers 54, 56 extend through the full length 58 of the first member body, such that the first member 20 has a generally hollow interior. In this embodiment the first member 20 is formed through an extrusion process, but it will be appreciated that this may differ in other embodiments. The lower and intermediate walls 44, 46 extend across and define the full length 58 of the first member 20. The upper wall 48 terminates inwards of the first and second ends 34, 36 of the first member 20, such that the upper wall 48 is shorter than the lower and intermediate walls 44, 46. In this way, gaps or openings 60 are defined in the battery support system 12 once assembled. These gaps or openings 60 allow for electronic and / or cooling apparatus associated with the battery cells 18 to pass through the battery support system 12, as will be explained further below. The pair of first member projections 42 comprises a left first member projection 62 and a right first member projection 64. Each first member projection 62, 64 extends from the lower wall 44 of the first member body 40 to define a generally flat rectangular ledge having an upper surface 66 and a lower surface 68 (see Figure 8). The left first member projection 62 extends laterally from the first member body 40 in a first direction 70 that is substantially perpendicularto the first longitudinal axis 38. The right first member projection 64 extends laterally from the first member body 40 in a second direction 72 that is substantially perpendicularto the first longitudinal axis 38, and opposed to the first direction 70. Each first member projection 62, 64 extends continuously across the full length 58 of the first member 20. In this embodiment, the first member projections 62, 64 have the same thickness as one another, and the same as the lower wall 44 of the first member body 40 from which they extend. In this way, and as best appreciated from Figures 3 and 8, the lower wall 44 and first member projections 62, 64 define a continuous lower plate 74 of the first member 20. Turning now to Figure 4, the second member 22 of the crossbeam 26 is shown in isolation. The second member 22 is elongate and extends from a first end 76 to a second end 78 along a second longitudinal axis 80. The second member 22 comprises a second member body 82 and a pair of second member projections 84. The second member body 82 comprises a lower wall 86 (not shown in Figure 4 but seen in Figure 8), an intermediate wall 88 and an upper wall 90. Left and right side walls 92, 94 of the second member body 82 extend between and join the lower wall 86, the intermediate wall 88 and the upper wall 90. As such, the lower wall 86, the intermediate wall 88 and the upper wall 90 are vertically spaced from one another to define an upper chamber 96 and a lower chamber 98 in the second member body 82. In this way, the second member 22 has a generally hollow interior. As with the first member 20, in this embodiment the second member 22 is formed through an extrusion process, but it will be appreciated that this may differ in other embodiments. The intermediate wall 88 extends across and defines the full length 100 of the second member 22. The upper and lower walls 90, 86 each terminate inwards of the first and second ends 76, 78 of the second member 22, such that the upper and lower walls 90, 86 are shorter than the intermediate wall 88. The second member body 82 comprises first and second cut-outs 101, 103 formed in the upper wall 90 and that span portions of the left and right side walls 92, 94. The first cut-out 101 is provided towards the first end 76 of the second member 22 and the second cut-out 103 is provided towards the second end 78 of the second member 22. These cut-outs 101, 103 provide openings 105 that provide clearance for projections 107 (see Figure 5) from the lower wall 124 of the third member 24 in the assembled arrangement. The pair of second member projections 84 comprises a left second member projection 102 and a right second member projection 104. Each second member projection 102, 104 extends from the intermediate wall 88 of the second member body 82 to define a generally flat ledge having an upper surface 106 and a lower surface 108 (see in Figure 8). The left second member projection 102 extends laterally from the second member body 82 in the first direction 70. The right second member projection 104 extends laterally from the second member body 82 in the second direction 72. As best appreciated from Figure 4, each second member projection 102, 104 spans almost the full length 100 of the second member 22. Each second member projection 102, 104 terminates inwards of each of the first and second ends 76, 78 of the second member 22 at sloped or chamfered first and second end edges 110,112. Turning now to Figure 5, the third member 24 of the crossbeam 26 is shown in isolation. The third member 24 is elongate and extends from a first end 114 to a second end 116 along a third longitudinal axis 118. The third member 24 comprises a third member body 120 having a generally rectangular cross-sectional profile and a pair of third member projections 122. The third member body 120 comprises a lower wall 124, an intermediate wall 126 and an upper wall 128. Left and right side walls 130, 132 of the third member body 120 extend between and join the lower wall 124, the intermediate wall 126 and the upper wall 128. As such, the lower wall 124, the intermediate wall 126 and the upper wall 128 are vertically spaced from one another to define an upper chamber 133 and a lower chamber 134 in the third member body 120 (see also Figure 8). The upper and lower chambers 133,134 extend through the full length of the third member body 120, such that the third member 24 has a generally hollow interior. As with the first and second members 20, 22, in this embodiment the third member 24 is formed through an extrusion process, but it will be appreciated that this may differ in other embodiments. Each side wall 130, 132 comprises bolt-receiving openings 134 at each end 114, 116 of the third member 24 for receiving bolts 135 (shown in Figure 7) for attaching the third member 24 to first and second adaptors 136, 138, as will be explained further below. The pair of third member projections 122 comprises a left third member projection 140 and a right third member projection 142. Each third member projection 140, 142 extends from the upper wall 128 of the third member body 120 to define a generally flat ledge having an upper surface 144 and a lower surface 146. The left third member projection 140 extends laterally from the third member body 120 in the first direction 70. The right third member projection 142 extends laterally from the third member body 120 in the second direction 72. In this embodiment, the third member projections 140, 142 have the same thickness as one another, and the same as the upper wall 128 of the third member body 120 from which the extend. In this way, and as best appreciated from Figure 8, the upper wall 128 and the third member projections 140, 142 together define a continuous upper plate 148 of the third member 24. To support an array of battery cells 18 in a vehicle 10, multiple crossbeams 26 comprising first, second and third members 20, 22, 24 are installed between the first and second side rails 28, 30 of the frame 32 of the vehicle 10, as shown in Figures 9 and 10 (noting that in Figure 10 only one side rail is illustrated). As will be appreciated by the skilled person, the first and second side rails 28, 39 extend longitudinally within the vehicle 10, at opposing sides of the vehicle 10. Thus, the crossbeams 26 extend laterally across the width of the vehicle 10. The crossbeams 26 are coupled to the first and second side rails 28, 30 via the first and second adaptors 136, 138 of the battery support system 12. It should be noted that the first and second adaptors 136, 138 are identical to one another. With reference to Figures 6 and 7, each adaptor 136, 138 comprises a generally planar main wall 150 having a first, inner, surface 152 and a second, outer, surface 153 that opposes the inner surface 152. The adaptors 136, 138 further comprise a pair of lower projections 156 and a pair of upper projections 158. The lower projections 156 are located towards a lower end 160 of the adaptor 136,138, at a generally central position across the width of the adaptor 136,138. Each lower projection 156 extends generally perpendicularly from the inner surface 152 of the main wall 150 of the first adaptor 136. Each lower projection 156 comprises sloped upper and lower edges 162, 164 that provide a taper between inner and outer edges 166, 168 of the lower projection 156. The upper projections 158 are located at an upper end 170 of the first adaptor 136, at a generally central position across the width of the first adaptor 136. Each upper projection 158 extends generally perpendicularly from the inner surface 152 of the main wall 150 of the first adaptor 136. Each upper projection 158 comprises sloped upper and lower edges 172, 174 that provide a taper between inner and outer edges 176, 178 of the upper projection 158. The upper projections 158 further comprise a plurality of bolt-receiving openings 180 for receiving attachment means in the form of bolts 135 that secure the third member 24 to the first adaptor 136. Referring now to Figure 9 in particular, in this embodiment the vehicle 10 includes four crossbeams 26 to support a dual-tier array of battery cells 18. To assemble the crossbeams 26 and associated battery cells 18 in the vehicle 10, each first member 20 of the four crossbeams 26 is arranged between the first and second side rails 28, 30, on flanges 179 of the first and second side rails 28, 30, (see Figure 2) and at predetermined positions along the length of the floor panel 16. The predetermined positions of the first members 20 are chosen to provide sufficient spacing between neighbouring first members 20 to receive battery cells 18 of the array. Each first member 20 is arranged such that its first longitudinal axis 38 is substantially perpendicular to both a longitudinal axis 182 of the first side rail 28 and a longitudinal axis 184 of the second side rail 30. Once in the correct position, each first member 20 is attached to a floor panel 16 of the battery support system 12 by selfpiercing rivets (not shown) that join the first member 20 to the floor panel 16 at a plurality of evenly spaced positions across the length of each of the first member projections 62, 64. The first members 20 span the full distance between the first and second side rails 28, 30 to provide global stiffness for the dual-tier battery pack, and local stiffness for the first tier 194 of battery cells 18 in the final arrangement. After securing each first member 20 to the floor panel 16, which itself is similarly fixed to the side rails 28, 30, first and second adaptors 136,138 are arranged between each first member 20 and the first and second side rails 28, 30. A first adaptor 136 is positioned at the first end 34 of each first member 20, and the outer surface 153 of the first adaptor 136 is engaged with and welded or riveted to an inner surface 186 of the first side rail 28. The first member body 40 is received in the space between the lower projections 156 of the first adaptor 136, and inner surfaces 188 of the lower projections 156 engage and are welded to outer surfaces 190 of the side walls 50, 52 of the first member body 40. Correspondingly, a second adaptor 138 is positioned at the second end 36 of each first member 20, and the outer surface 153 of the second adaptor 138 is engaged with and welded to an inner surface 187 of the second side rail 30. The first member body 40 is received in the space between the lower projections 156 of the second adaptor 138, and the inner surfaces 188 of the lower projections 156 engage and are welded to the outer surfaces 190 of the side walls 50, 52 of the first member body 40. In this way, each first member 20 is secured directly to the floor panel 16, and to the first and second side rails 28, 30 via the first and second adaptors 136, 138, respectively. It is to be understood that any connection mechanism may be employed, including adhesion or riveting. The point here is that it need not be a dismantlable connection but can be permanent fixation. Following attachment of the first members 20 to the floor panel 16 and side rails 28, 20, battery cells 18 are arranged between and supported on neighbouring first members 20 to form a first layer or tier 194 of battery cells 18. In this example, the battery cells 18 each include cooling means in the form of a cooling plate 196 (part of which can be seen in Figure 10) provided at an upper side of the battery cells 18. Each battery cell 18 extends between two neighbouring first members 20, and sits on a first member projection 62, 64 of each first member 20. Each battery cell 18 is secured to each first member projection 62, 64 with adhesive. Once the first tier 194 of battery cells 18 is arranged and secured in the floor panel 16 as described, a second member 22 is added to the arrangement. A second member 22 is arranged on top of each of the installed first members 20, such that a lower surface 198 of the lower wall 86 of each second member 22 engages an upper surface 200 of the upper wall 48 of the associated first member 20. The second longitudinal axis 80 of each second member 22 is substantially parallel to the first longitudinal axis 38 of the associated first member 20. When positioned in this way, the longitudinal axes 38, 80 of the first and second members 20, 22 of each crossbeam 26 are arranged in a vertical plane, and the first and second members 20, 22 of each crossbeam 26 form a vertical stack. Opposed first and second member projections 62,64,102,104 extend in substantially parallel planes to define a first gap 201 between them in which end portions of battery cells 18 of the first tier 194 are located. Each second member 22 is attached to its associated first member 20 using attachment means in the form of bolts and adhesive (not shown). Adhesive is provided between the upper surface 200 of the upper wall 48 of the first member 20 and the lower surface 198 of the lower wall 86 of the second member 22. The bolted connections between each first and second member 20, 22 are provided at multiple positions along the length of each crossbeam 26 through corresponding bolt-receiving openings 202 in the first and second members 20, 22. The use of both adhesive and bolted connections to secure the first and second members 20, 22 to one another is advantageous to guard against both lateral and vertical relative movement between the first and second members 20, 22. The adhesive connection ensures sufficient shear strength of the arrangement, and the bolted connections ensure sufficient peal strength of the arrangement. Each second member projection 102, 104 is attached to the battery cells 18 beneath them using adhesive applied between the upper side of the battery cells 18 and the lower surface 108 of each second member projection 102, 104. Once each second member 22 is assembled as described, a second layer or tier 204 of battery cells 18 is arranged on top of the first tier 194 of battery cells 18. Each battery cell 18 extends between two neighbouring second members 22, and sits on a second member projection 102, 104 of each of the neighbouring second members 22. Each battery cell 18 is secured in the arrangement through adhesive between a lower side of the battery cell 18 and the upper surface 106 of the second member projection 102,104. It will be appreciated that, in contrast to the first member projections 62, 64 that are supported by the floor panel 16 and side rail flanges 179, the second member projections 102, 104 are not supported by other structural components, and further bear the weight of the second tier 204 of battery cells 18. As such, in this embodiment the second member 22 is formed from a higher-strength grade of aluminium than the first member 20 in order to enable sufficient support of the second tier 204 by the second member projections 102, 104. It will be appreciated that in other embodiments sufficient strength of the second member projections 102, 104 could be ensured through different means, for example by use of thicker material or a different high strength material altogether. Once the second tier 204 of battery cells 18 is assembled as described, a third member 26 is added to the arrangement for each crossbeam 26. A third member 26 is arranged on top of each second member 24, such that a lower surface 206 ofthe lower wall 124 of each third member 24 engages an upper surface 208 of the upper wall 90 ofthe associated second member 24. The third longitudinal axis 118 of each third member 26 is substantially parallel to the first longitudinal axis 38 of the associated first member 20 and the second longitudinal axis 80 ofthe associated second member 24. As such, the longitudinal axes 38, 80, 118 ofthe first, second and third members 20, 22, 24 of each crossbeam 26 are arranged in a vertical plane, and the first, second and third members 20, 22, 24 of each crossbeam 26 form a vertical stack. Opposed second and third member projections 102,104,140,142 extend in substantially parallel planes to define a second gap 203 between them in which end portions of battery cells 18 ofthe second tier 204 are housed. Each third member 24 is attached to its associated second member 22 using attachment means in the form of bolts and adhesive (not shown). Adhesive is provided between the upper surface 208 of the upper wall 90 of the second member 22 and the lower surface 206 of the lower wall 124 of the third member 24. The bolted connections between each second and third member 22, 24 are provided at multiple positions along the length of each crossbeam 26 through corresponding bolt-receiving openings 210 in the second and third members 22, 24. As discussed above in relation to the connections between the first and second members 20, 22, the use of both adhesive and bolted connections here is advantageous to ensure sufficient shear and peal strength of the arrangement. The third member body 120 is received in the spaces between the upper projections 158 of the firstand second adaptors 136, 138. With reference to Figures 6 and 7 in particular, each third member 24 is attached to the first and second adaptors 136, 138 through pins or bolts 135 received through corresponding bolt-receiving openings 139,180 respectively of the third member 24 and the first and second adaptors 136,138. Between them, they define clevis style joints. Each third member projection 140, 142 is attached to the battery cells 18 beneath using adhesive applied between the upper side of the battery cells 18 and the lower surface 146 of each third member projection 140, 142. The third member 24, which defines the primary lateral load path across the battery support system 12, is formed of the same high-strength aluminium as the second member 22 in this embodiment. Figure 11 shows a side view of an assembled crossbeam 26 and associated first and second adaptors 136, 138. It will be appreciated from Figure 11 that in addition to the openings 105 of the second member 22 that accommodate projections 107 of the third member 24, openings 216 are defined between the elements of the crossbeam 26 and adaptor 136, 138 to provide through paths for electronic and / or cooling apparatus associated with the battery cells 18. In this embodiment, the openings 216 receive busbars and cooling apparatus (not shown) that connect between battery cells 18 of neighbouring regions 212. In other embodiments the arrangement of pass-through openings in the assembled crossbeams 26 may vary. One such alternative embodiment is shown in Figure 12, which includes central openings 218 for receiving busbars and end openings 220 for receiving cooling apparatus. It will be appreciated that other arrangements are possible. As noted already, in the final assembly of the battery support system 12 and associated battery cells 18, four crossbeams 26 are arranged in the floor panel 16 between the first and second side rails 28, 30 as shown in Figure 9. This provides three regions 212 between neighbouring crossbeams 26 in which battery cells 18 are arranged. In this way, in this embodiment the final assembly includes three rows of battery cells 18, each row being defined by a dual-tier stack of battery cells 18 as described. The battery support system 12 of the invention advantageously provides lateral structural support to battery cells 18 housed in the battery frame 32, as well as contributing to overall battery stiffness. The crossbeams 26 extend across the vehicle 10, and are coupled to the side rails 28, 30 of the vehicle 10, allowing lateral load on the vehicle 10 to be dissipated through the crossbeams 26 and side rails 28, 30, potentially bypassing and protecting the battery cells 18 housed within. This allows for the battery cells 18 to be incorporated in the vehicle 10 without being housed in conventional modules that would normally provide the battery cells 18 with structural support and protection, thus reducing the weight associated with the battery structures themselves. Furthermore, the crossbeams 26 may be formed from relatively lightweight extruded components, which may provide further weight reduction. It will be appreciated that reduction of the weight of such vehicle components has a positive impact on energy requirements of the vehicle 10. In addition to the above, the crossbeams 26 advantageously provide through paths for elements that are required to connect between battery cells 18 of neighbouring regions 212, e.g. electrical and cooling apparatus. This is particularly useful for such a two-tier battery system, in which routing such electrical and cooling apparatus between battery cells 18 of neighbouring regions 212 would otherwise be complex. Further still, the method of assembling the battery support system 12 of the invention and its associated battery cells 18 accounts for the need to consider different joining / attachment methods at different stages of the process, due to the use of unpackaged battery cells 18 (i.e. battery cells not housed in conventional modules). For example, the method of the invention appreciates that welding or riveting can be used to secure the first members 20 and adaptors 136,138 in place and to the floor member 16, because at this stage no battery cells 18 are present. However, once the first tier 194 of battery cells 18 is arranged in the floor panel 16, other attachment methods such as bolts and adhesive are utilised to avoid damage to the battery cells 18 and to enable later disassembly for servicing etc. It should be noted that the number of crossbeams 26 may vary in other embodiments, for example depending on the size of the vehicle 10 and the number of battery cells 18 that the battery support system 12 is required to support. It will also be appreciated that although each crossbeam 26 includes three members 20, 22, 24 to support two tiers of battery cells 18 in this embodiment, in other embodiments this may vary. For example, in a system required to support a single tier of battery cells, the third member 24 may be omitted from each crossbeam 26. It will also be appreciated that although each of the crossbeams 26 are identical in this embodiment, this may differ in other embodiments. For example, in some embodiments the members that form the outermost crossbeams 26, and thus only support battery cells 18 along one side, may include only one projection along the relevant battery cell supporting side. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A battery support system for supporting an array of battery cells, the battery support system comprising first and second side rails and a crossmember, wherein the crossmember comprises:a first member comprising an elongate first member body and a first member projection that extends laterally from the first member body in a direction that is substantially perpendicular to a longitudinal axis of the first member, wherein the first member extends between and is attached to the first and second side rails such that the longitudinal axis of the first member is substantially perpendicular to a longitudinal axis of each of the first and second side rails; anda second member comprising an elongate second member body and a second member projection that extends laterally from the second member body in a direction that is generally perpendicular to a longitudinal axis of the second member, wherein the second member is vertically stacked on and attached to the first member such that the longitudinal axis of the second member is substantially parallel to the longitudinal axis of the first member, and the first and second member projections extend in substantially parallel planes to define a first gap between them for receiving at least a portion of one or more battery cells of a first tier of the array.

2. The battery support system of Claim 1, comprising a third member that comprises an elongate third member body and a third member projection that extends laterally from the third member body in a direction that is substantially perpendicular to a longitudinal axis of the third member, wherein the third member is vertically stacked on and attached to the second member such that the longitudinal axis of the third member is substantially parallel to the longitudinal axes of the first and second members, and the second and third member projections extend in substantially parallel planes to define a second gap between them for receiving at least a portion of one or more battery cells of a second tier of the array.

3. The battery support system of Claim 1 or Claim 2, comprising first and second adaptors for attaching the first member to the first and second side rails, wherein the first adaptor is permanently fixed to the first side rail and the second adaptor is permanently fixed to the second side rail.

4. The battery support system of Claim 3, wherein a first end of the first member is permanently fixed to the first adaptor, and a second end of the first member is permanently fixed to the second adaptor.

5. The battery support system of Claim 3 or Claim 4 when depending through Claim 2, wherein the third member is attached to the first and second side rails via the first and second adaptors, wherein a first end of the third member is bolted to the first adaptor and a second end of the third member is bolted to the second adaptor.

6. The battery support system of any preceding claim, wherein the crossmember comprises at least one opening configured to receive electronic or cooling apparatus extending between battery cells positioned on opposing sides of the crossmember.

7. The battery support system of any preceding claim, wherein the second member is attached to thefirst member using adhesive and / or bolted connections.

8. The battery support system of any of Claims 3 to 7 when depending through Claim 2, wherein the third member is attached to the second member using adhesive and / or bolted connections.

9. The battery support system of any of Claims 3 to 8 when depending through Claim 2, in combination with a first tier of battery cells located at least partially in the first gap and secured to the first and second member projections, and a second tier of battery cells located at least partially in the second gap and secured to the second and third projections.

10. A vehicle comprising the battery support system of any preceding claim.

11. A method of assembling an apparatus for supporting an array of battery cells in a vehicle, theapparatus comprising a first member and a second member, wherein the first member comprises an elongate first member body and a first member projection and the second member comprises an elongate second member body and a second member projection, the method comprising:attaching the first member to opposed first and second side rails such that the first member extends between the first and second side rails, and a longitudinal axis of the first member is substantially perpendicular to a longitudinal axis of each of the first and second side rails;securing a first tier of battery cells to the first member projection; andvertically stacking the second member on top of the first member and attaching the second member to the first member, such that a longitudinal axis of the second member is substantially parallel to the longitudinal axis of the first member, the first and second member projections extend in substantially parallel planes, and at least a portion of each battery cell of the first tier is positioned in a first gap defined between the first and second member projections.

12. The method of Claim 11, comprising arranging a second tier of battery cells above the first tier of battery cells, and securing the battery cells of the second tier to the second member projection.

13. The method of Claim 12, comprising vertically stacking a third member comprising an elongate third member body and a third member projection on top of the second member and attaching the third member to the second member, such that a longitudinal axis of the third member is substantially parallel to the longitudinal axes of the first and second members, the second and third member projections extend in substantially parallel planes, and at least a portion of each battery cell of the second tier is positioned in a second gap defined between the second and third member projections.

14. The method of any of Claims 11 to 13 comprising attaching the first member to the first and second side rails by:permanently fixing a first adaptor to the first side rail;permanently fixing a second adaptor to the second side rail;permanently fixing a first end of the first member to the first adaptor; andpermanently fixing a second end of the first member to the second adaptor.5 15. The method of Claim 14 when depending through Claim 13, comprising attaching the third memberto the first and second side rails by:bolting a first end of the third member to the first adaptor; andbolting a second end of the third member to the second adaptor.

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