A base plate for a battery frame of a vehicle battery assembly

Abstract

Aspects of the present invention relate to a base plate (302) for a battery frame (208) of a vehicle battery assembly (200). The battery frame comprises a cantilevered support (218) extending in a transverse plane (220) to support a battery cell (206) in the vehicle battery assembly. The base plate (302) has an attachment portion (308) attachable to the battery frame (208), a cover portion (306) offset from the attachment portion in a direction perpendicular to the transverse plane, and a transition portion (312) joining an edge (318) of the attachment portion (308) to the cover portion (306). The edge of the attachment portion is non-linear in the transverse plane and positioned to at least partially underlie the cantilevered support (218) when the attachment portion (308) is attached to the battery frame (208).

Description

[0001] A BASE PLATE FOR A BATTERY FRAME OF A VEHICLE BATTERY ASSEMBLY

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a base plate for a battery frame of a vehicle battery assembly. Aspects of the invention relate to a base plate of a battery frame of a vehicle battery assembly, a battery frame of a vehicle battery assembly, to a vehicle battery assembly, and to a vehicle.

[0004] BACKGROUND

[0005] It is known to provide a vehicle battery assembly formed of a battery frame that supports a plurality of secondary battery cells. The secondary battery cells have a significant weight and the battery frame has to be sufficiently strong to support the weight of the secondary battery cells, including during movement of the vehicle. There is also a desire to minimise the weight of the battery frame so as not to increase the weight of the vehicle battery assembly (and vehicle).

[0006] It is an aim of the present invention to address one or more disadvantages associated with the prior art.

[0007] SUMMARY OF THE INVENTION

[0008] Aspects and embodiments of the invention provide a base plate for a battery frame of a vehicle battery assembly, a battery frame of a vehicle battery assembly, a vehicle battery assembly, and a vehicle as claimed in the appended claims.

[0009] According to an aspect of the invention there is provided a base plate for a battery frame of a vehicle battery assembly, wherein the battery frame comprises a cantilevered support extending in a transverse plane to support a battery cell in the vehicle battery assembly, wherein the base plate comprises an attachment portion attachable to the battery frame, a cover portion offset from the attachment portion in a direction perpendicular to the transverse plane, and a transition portion joining an edge of the attachment portion to the cover portion.

[0010] According to an aspect of the invention there is provided a base plate for a battery frame of a vehicle battery assembly, wherein the battery frame comprises a cantilevered support extending in a transverse plane to support at least one battery cell in the vehicle battery assembly, wherein the base plate comprises an attachment portion attachable to the battery frame, a cover portion offset from the attachment portion in a direction perpendicular to the transverse plane, and a transition portion joining an edge of the attachment portion to the cover portion, wherein the edge of the attachment portion is non-linear in the transverse plane and positioned to at least partially underlie the cantilevered support when the attachment portion is attached to the battery frame.

[0011] Advantageously, the non-linear edge of the attachment portion improves the support provided to the cantilevered support by the base plate in the vehicle battery assembly. In particular, the base plate itself is stiffened by forming the non-linear profile of the transition portion. Additionally, the limit of the contact between the attachment portion and the cantilevered support along the edge is not a straight line, so there is no bending of the cantilevered support about a straight line. In particular, in the vehicle battery assembly the cantilevered support bears the weight of the battery cell so is subject to a bending load acting towards the base plate, and the cantilevered support is supported by the underlying attachment portion that is in contact with the cantilevered support. The non-linear edge of the attachment portion at least partly underlying the cantilevered support avoids any straight line about which this bending load acts on the cantilevered support, and therefore reduces the bending stress imparted on the cantilevered support. Accordingly, it may be possible to use thinner and / or lighter materials for the battery frame (e.g., an end section or a crossmember), and / or for the cantilevered support, and / or the base plate while still providing support to the battery cell within the vehicle battery assembly.

[0012] In examples, the battery frame comprises an end section and the cantilevered support extends from the end section. In such examples the attachment portion of the base plate is attachable to the end section. In other examples, the battery frame comprises a crossmember and the cantilevered support extends from the crossmember. In such examples the attachment portion of the base plate is attachable to the crossmember. The end section may be located at an end of the battery frame (e.g., a front end, rear end, or side). The crossmember may extend transversely or longitudinally across the battery frame between end sections. Advantageously, the base plate may include an attachment portion with a non-linear edge arranged to support any cantilevered support of the vehicle battery assembly that is subject to a bending load, particularly a bending load due to the weight of the battery cells.

[0013] In examples, the edge of the attachment portion is curved, wavy, or zig-zag. The edge may comprise a curve having at least one peak and at least one trough, for example a plurality of peaks and a plurality of troughs.

[0014] Advantageously, a curved, wavy, or zig-zag edge ensures that there is no straight line about which the bending load of the battery cells acts on the cantilevered support, and therefore reduces the bending stress imparted on the cantilevered support. Accordingly, it may be possible to use thinner and / or lighter materials for components of the battery frame (particularly the cantilevered support).

[0015] In examples, the base plate comprises an end and the attachment portion extends between the edge and the end. Advantageously, the non-linear edge of the attachment portion can support a cantilevered support extending from an end section of the battery frame.

[0016] In examples, the end is attachable (e.g., weldable) to the battery frame, in particular to an end section of the battery frame. Accordingly, one side of the attachment portion is attached to the battery frame and the other side of the attachment portion has the non-linear edge, advantageously providing support for the cantilevered support.

[0017] In examples, the attachment portion is planar between the edge and the end. Advantageously, the attachment portion and cantilevered support are both planar and in contact over a surface area that provides support for the cantilevered support to resist a bending load of the battery cell. In examples, the base plate comprises an aluminium plate. The aluminium plate may have a thickness of between about 1 mm and about 4 mm, for example about 2 mm or about 3 mm. Optionally, the base plate is formed by stamping (it is stamped). Advantageously, aluminium provides a lightweight base plate with good impact resistance, structural rigidity, and corrosion resistance.

[0018] In examples, the base plate may form an outer (bottom) surface of the vehicle. The base plate advantageously provides sealing and impact resistance.

[0019] According to a further aspect of the present invention, there is provided a battery frame of a vehicle battery assembly, the battery frame comprising a cantilevered support extending in a transverse direction to support a battery cell in the vehicle battery assembly, and the base plate described above. The attachment portion of the base plate is attached to the battery frame such that the transition portion at least partially underlies the cantilevered support.

[0020] Advantageously, as explained above, the non-linear (e.g., curved, wavy or zig-zag) edge of the attachment portion improves the support provided to the cantilevered support by the base plate in the vehicle battery assembly and it may be possible to use thinner and / or lighter materials for components of the battery frame.

[0021] In examples, the battery frame comprises an end section and the cantilevered support extends from the end section. In such examples the attachment portion of the base plate is attachable to the end section. In other examples, the battery frame comprises a crossmember and the cantilevered support extends from the crossmember. In such examples the attachment portion of the base plate is attachable to the crossmember.

[0022] In examples, the edge of the attachment portion of the base plate completely underlies the cantilevered support. Advantageously, in this arrangement the bending load of the battery cell is spread across the entire non-linear edge of the attachment portion and there is no straight line about which the bending load acts on the cantilevered support.

[0023] In examples, the battery frame comprises an end section, the cantilevered support extends from the end section, and the attachment portion of the base plate is welded to the end section. Advantageously, a welded attachment provides a strong attachment that attaches the base plate to the end section and provides support for the cantilevered support against a bending load imparted by the battery cell. The weld also provides a seal between the base plate and the end section.

[0024] In other examples, the battery frame comprises a crossmember and the cantilevered support extends from the crossmember. In such examples the attachment portion may be welded to the crossmember.

[0025] In examples, the base plate comprises an end and the attachment portion extends between the edge and the end,. The end of the base plate may be welded to the end section. In examples, the end of the base plate is welded to the end section by a seam weld, for example a seam weld extending along the entire end of the base plate. Advantageously, this provides a strong attachment and sealing between the base plate and the end section. In examples, an entire outer edge of the base plate, including the end, is welded to the battery frame (including the end section and other structural components of the battery frame).

[0026] In examples, the battery frame comprises an inner panel overlying the base plate, the inner panel comprising an end received on the cantilevered support on an opposite side to the base plate. Advantageously, the layered arrangement of the inner panel, cantilevered support and base plate provides support against the bending load of the battery cell and sealing of the interior of the vehicle battery assembly.

[0027] In other examples, the battery frame comprises a crossmember and the cantilevered support extends from the crossmember. In such examples a part of the inner panel may be received on the cantilevered support on an opposite side to the base plate.

[0028] In examples, the end of the inner panel is attached to the cantilevered support. Advantageously, at least some of the bending load of the battery cell may be borne by the inner panel.

[0029] In examples, the end of the inner panel is welded and / or rivetted and / or adhered to the cantilevered support.

[0030] In examples, the end of the inner panel is rivetted and adhered to the cantilevered support, the adhesive being provided in the same location as the rivet. In examples, the rivets may be disposed in a part of the cantilevered support where the base plate is spaced from the underside of the cantilevered support due to the non-linear edge. For example, if the non-linear edge comprises peaks and troughs, the rivets may be aligned with the troughs so as to avoid contact with the base plate. Accordingly, the rivet advantageously does not contact or pierce the base plate and the base plate maintains a seal.

[0031] In examples, the inner panel comprises an aluminium plate. The aluminium plate may have a thickness of between about 1 mm and about 4 mm, for example about 2 mm or about 3 mm. Optionally, the inner panel is formed by stamping (it is stamped). Advantageously, aluminium provides a lightweight inner panel with good impact resistance, structural rigidity, and corrosion resistance.

[0032] In examples, the battery frame comprises a beam having a bottom surface, and wherein the cantilevered support extends from the beam in the transverse direction parallel to the bottom surface of the beam.

[0033] In examples, the beam may comprise a box section. The beam may be an end section or crossmember of the battery frame. Advantageously, the beam provides structural rigidity for the battery frame and support for the load of the battery cell.

[0034] In examples, the attachment portion of the base plate is attached to the bottom surface of the beam. In examples, the edge of the attachment portion underlies the bottom surface and the cantilevered support of the beam.

[0035] Advantageously, the attachment portion of the base plate is attached the beam (e.g., end section or crossmember) at a location spaced from the non-linear edge and cantilevered support. This maintains attachment and sealing and ensures good contact between the attachment portion and the cantilevered support to support the bending load of the battery cell.

[0036] In examples, the end section is a rear section or a front section of the battery frame relative to the forward travelling direction of the vehicle. The beam may extend transversely to the forward direction of the vehicle. In other examples, the end section may be a side section of the battery frame and the beam may extend in parallel to the forward direction of the vehicle.

[0037] According to a further aspect of the present invention there is provided a vehicle battery assembly of a vehicle, comprising the battery frame described above and a battery cell supported on the cantilevered support.

[0038] The battery cell may be a secondary battery cell. The vehicle battery assembly may comprise a plurality of (secondary) battery cells. In examples the plurality of secondary cells are prismatic cells of the same format and mass, and so provide a distributed load along the cantilevered support.

[0039] According to a further aspect of the present invention there is provided a vehicle comprising the vehicle battery assembly described above.

[0040] In examples, the vehicle is a battery electric vehicle, or a hybrid vehicle (e.g., a plug-in hybrid vehicle or a mild hybrid vehicle). The vehicle battery assembly may be a primary or secondary energy source for vehicle propulsion. The vehicle battery assembly may be a traction battery of the vehicle.

[0041] 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 any way 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.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0044] Figure 1 shows a vehicle according to embodiments of the invention. Figure 2 shows a vehicle battery assembly of the vehicle of Figure 1 according to embodiments of the invention.

[0045] Figure 3 shows a side view of one end of the vehicle battery assembly of Figure 2.

[0046] Figure 4 shows an exploded view of a part of the vehicle battery assembly of Figure 2.

[0047] Figure 5A shows a perspective view of the base plate of the vehicle battery assembly according to embodiments of the invention.

[0048] Figure 5B shows a top view of the base plate of Figure 5A.

[0049] Figure 5C shows the positioning of a line of rivets in relation to peaks and troughs in the edge of an attachment portion of the base plate of Figure 5A and Figure 5B.

[0050] Figure 6A shows a perspective cross-sectional view at one position of one end of the vehicle battery assembly of Figure 2.

[0051] Figure 6B shows a perspective cross-sectional view at one position of a second end of the vehicle battery assembly of Figure 2.

[0052] Figure 7 shows a top view of an alternative example base plate according to embodiments of the invention.

[0053] DETAILED DESCRIPTION

[0054] A vehicle 100 in accordance with an embodiment of the present invention is shown in Figure 1. Figure 2 shows a schematic cross-section through a vehicle battery assembly 200 of the vehicle 100. The cross-section is taken through a plane extending longitudinally through the vehicle, vertically from a front of the vehicle to a rear of the vehicle. The vehicle battery assembly 200 is installed on an underside of the vehicle 100. The vehicle battery assembly 200 includes a plurality of fixings 210 for mounting the vehicle battery assembly 200 to the underside of the vehicle 100. The fixings 210 may attach to various parts of the underside of the vehicle 100, for example parts of a chassis and / or monocoque and / or other structural members of the vehicle 100.

[0055] The vehicle battery assembly 200 houses a plurality of battery cells 206. The battery cells 206 may be secondary cells of the vehicle battery assembly 200. The vehicle battery assembly 200 may also house battery monitoring systems, control systems, cooling systems, and other sub-assemblies (not illustrated).

[0056] In examples the vehicle battery assembly 200 is a traction battery. In examples, the vehicle 100 may be a battery electric vehicle, a hybrid vehicle (e.g., a plug-in hybrid vehicle, or a mild hybrid vehicle). The vehicle battery assembly 200 may be a primary or secondary energy source for vehicle propulsion.

[0057] The vehicle battery assembly 200 shown in Figure 2 includes a battery frame 208. The battery frame 208 includes crossmembers 202 that extend transversely across the vehicle battery assembly 200. In this example, the battery frame 208 includes four crossmembers 202, but in various examples the battery frame 208 may comprise two or more crossmembers 202. The battery frame 208 also includes end sections 212 at each end of the battery frame 208. The end sections 212 are similar to the crossmembers 202. The end sections 212 and the crossmembers 202 extend in a first direction across the vehicle battery assembly 200. In some examples the vehicle battery assembly 200 may include end sections 212 and no crossmembers 202. The fixings 210 may be attached to the crossmembers 202 and / or end sections 212 for mounting the vehicle battery assembly 200 to the vehicle. The battery frame 208 includes a battery lid 211 attached to the top of crossmembers 202 and end sections 212. The battery frame 208 includes a base plate assembly 300 mounted to the bottom of the crossmembers 202 and end sections 212. The base plate assembly 300 forms the bottom of the vehicle battery assembly 200. The base plate assembly 300 may be exposed below the vehicle 100 and provide sealing and protection for the battery cells 206 within the vehicle battery assembly 200. The battery frame 208, in particular the crossmembers 202 and end sections 212, provide internal mounting for the battery cells 206 and other sub-assemblies. For example, a stack of battery cells 206 may be supported by the crossmembers 202 and end sections 212 as illustrated.

[0058] Figure 3 shows a side view of a part of the vehicle battery assembly 200 of Figure 2. In particular, Figure 3 shows an end section 212, one ofthe crossmembers 202, the base plate assembly 300, and one of the battery cells 206. Figure 3 shows one end of the vehicle battery assembly 200, in particular a rear end of the vehicle battery assembly 200 located towards the rear wheels of the vehicle when mounted. However, it will be appreciated that the arrangement illustrated in Figure 3 may additionally or alternatively be provided elsewhere in the vehicle battery assembly 200, for example at a front end of the vehicle battery assembly 200, or at one or more sides of the vehicle battery assembly 200.

[0059] As shown in Figure 3, the crossmember 202 includes a cantilevered support, in this example a flange 214, on which the battery cell 206 is supported. The cantilevered support extends in a second direction, perpendicular to the first direction. The end section 212 includes a beam 216 and a cantilevered support 218 on which the battery cell 206 is supported. The cantilevered support 218 extends in the second direction, perpendicular to the first direction. In this example the beam 216 is a box section. The cantilevered support 218 extends from (is cantilevered from) the beam 216. In some examples the cantilevered support 218 is integrally formed with the beam 216. The crossmember 202 comprises a beam or box section and the flange 214 extends from the crossmember 202. The cantilevered support 218 on the end section 212 is parallel with the flange 214 on the crossmember 202. The underside of the cantilevered support 218 on the end section 212 defines a transverse plane 220. The underside of the flange 214 may be arranged on the same transverse plane 220, or may be offset from the transverse plane 220. Therefore the transverse plane 220 is a plane which extends transversely across the vehicle battery assembly 200, being aligned with the underside of the cantilevered support 218. In the examples of Figures 2, 3, 4, 6A and 6B the transverse plane extends in the first direction and the second direction.

[0060] In examples, the cantilevered support 218 may comprise 3 mm thick aluminium. In examples, the beam 216 is formed from 3 mm thick aluminium. The beam 216 may be extruded.

[0061] In some examples, the end section 212 is a rear section or a front section of the battery frame 208 relative to the forward travelling direction of the vehicle. The beam 216 may extend transversely to the forward direction of the vehicle. That is, the first direction is across the vehicle, and so is perpendicular to the forward direction of the vehicle. In other examples, the end section 212 may be a side section of the battery frame 208 and the beam 216 may extend in parallel to the forward direction of the vehicle. That is, the first direction is parallel to the forward direction of the vehicle. In some examples the battery cell may be a secondary battery cell and the vehicle battery assembly comprises a plurality of prismatic secondary battery cells, each cell having the same format and mass, and so providing a consistent distributed load along the cantilevered support 218 of the beam 216 in the first direction.

[0062] The battery cell 206 is supported on the flange 214 and on the cantilevered support 218 and spans between the end section 212 and the crossmember 202. In this way, the cantilevered support 218 on the end section 212 and the cantilevered support (flange 214) on the crossmember 202 bearthe weight of the battery cell 206. Optionally, the battery cell 206 may be fastened or clamped to the crossmember 202 and / or the end section 212, in particular the flange 214 and / or cantilevered support 218.

[0063] The base plate assembly 300 is attached to the crossmember 202 and the end section 212 and underlies the battery cell 206. The base plate assembly 300 defines a base of the vehicle battery assembly 200. In particular, the base plate assembly 300 may be attached to the flange 214 of the crossmember 202, and to the beam 216 and / or cantilevered support 218 of the end section 212. The base plate assembly 300 includes a base plate 302 and an inner panel 304. In examples, inner panel 304 is attached to the crossmembers 202 and the end sections 212, and the base plate 302 is attached to the inner panel 304 and the end section 212 and optionally also the crossmember 202. The inner panel 304 is disposed between the base plate 202 and the battery cell 206.

[0064] The base plate 302 and the inner panel 304 are metal, for example aluminium. The base plate 302 may comprise a thickness of 2 mm. The inner panel 304 may comprise a thickness of 2 mm.

[0065] Figure 4 shows an exploded view of the base plate assembly 300 and the end section 212. As shown in Figures 3 and 4, the cantilevered support 218 of the end section is disposed between the inner panel 304 and the base plate 302 when assembled. In particular, the cantilevered support 218 is disposed between an attachment portion 308 of the base plate 302 and an end 320 of the inner panel 304. The attachment portion 308, cantilevered support 218 and end 320 of the inner panel 304 are each planar (flat) and parallel to each other where they are in contact.

[0066] Figures 5A and 5B illustrate the base plate 302 in isolation, and Figures 6A and 6B show the base plate assembly 300 attached to the end section 212. As shown, the base plate 302 includes a cover portion 306. The cover portion 306 provides a protective cover for the underside of the vehicle battery assembly 200 as shown in Figure 3. The cover portion 306 forms a majority of the base plate 302.

[0067] The base plate 302 also includes an end 310. In this example the end 310 is a rear end of the base plate 302 but it will be appreciated that it may alternatively or additionally be another end or side of the base plate 302. The attachment portion 308 extends alongside the end 310 the base plate 302 and abuts against, and attaches to, the end section 212 as shown in Figures 6A and 6B. In particular, the attachment portion 308 may be adhered and / or welded and / or fastened to the end section 212. In examples, the end 310 is welded to the end section 212 so that the base plate 302 provides a seal for the vehicle battery assembly 200. The end 310 may be seam welded to the end section 212 along the entire end 310. In examples the end 310 is seam welded to the end section 212 and there is no adhesive provided between the attachment portion 308 and the end section 212.

[0068] As shown in Figures 6A and 6B, at least a part of the attachment portion 308 underlies the cantilevered support 218 of the end section 212 when assembled. A transition portion 312 joins the attachment portion 308 to the cover portion 306. The transition portion 312 extends at least partly in a direction perpendicular to the plane of the cantilevered support 218 of the end section 212. In this way, the cover portion 306 is offset from the attachment portion 308 in a direction perpendicular to the (transverse) plane of the cantilevered support 218. Accordingly, the cover portion 306 is spaced from the plane of the cantilevered support 218 by the transition portion 312.

[0069] In this example, in the plane of the cross-section shown in Figures 6A and 6B (perpendicular to the transverse plane 220 of the cantilevered support 212 shown in Figure 3) the transition portion 312 includes a first curve joining to the attachment portion 308 and a second curve joining to the cover portion 306. The base plate 302 may be pressed or stamped from sheet metal.

[0070] The attachment portion 308 is joined to the transition portion 212 along an edge 318. In this way, the edge 318 is an edge of the attachment portion 308. The attachment portion 308 is thereby defined between the end 310 and the edge 318. The attachment portion 308 is planar (flat) between the end 310 and the edge 318.

[0071] On one side of the edge 318 the attachment portion 308 abuts against the end section 212, in particular the underside of the beam 216 and the underside of the cantilevered support 218. On the other side of the edge 318 the transition portion 312 extends away from the cantilevered support 218 in a direction at least partly perpendicular to the plane of the cantilevered support 218. Accordingly, the edge 318 defines the limit of contact between the base plate 302 and the cantilevered support 218.

[0072] As shown in Figure 5B, the edge 318 of the attachment portion 308 is non-linear. In other words, the edge 318 of the attachment portion 308 extends along a non-linear line in the plane of the cantilevered support 218 (the transverse plane 220 shown in Figure 3).

[0073] In particular, the edge 318 of the attachment portion 308 includes at least one curve, in this example a plurality of curves arranged in a wavy line as shown most clearly in Figures 5A and 5B. In the illustrated example the entire edge 318 of the attachment portion 308 is a wavy line. In other examples, only a part of the edge 318 of the attachment portion 308 may be a wavy line (the remainder being a straight line).

[0074] In the illustrated example the edge 318 of the attachment portion 308 includes peaks 314 and troughs 316, and the peaks 314 extend further underneath the cantilevered support 218 than the troughs 316. In this example the wavy line is irregular, with the peaks 314 having a smaller radius than the troughs 316. However, in other examples the troughs 316 may have a smaller radius than the peaks 314, or the peaks 314 and troughs 316 may have the same radius (the wavy line may be regular). In the illustrated example the edge 318 of the attachment portion 308 comprises five peaks 314 and six troughs 316. In other examples, the edge 318 of the attachment portion 308 may comprise five troughs 316 and six peaks 314. It will be appreciated that the edge 318 of the attachment portion 308 may comprise two or more peaks 314 and two or more troughs 316. There may be one more peak 314 than trough 316, or vice versa. In some examples the edge 318 may comprise one trough 316 and two peaks 314, or one peak 314 and two troughs 316.

[0075] As shown in Figure 6A, the peak(s) 314 of the edge 318 are disposed proximate to the inner edge of the cantilevered support 218, and the trough(s) 316 of the edge 318 are disposed proximate to where the cantilevered support 218 extends from the beam 216, or may be underneath the beam 216.

[0076] In another example illustrated in Figure 7, the edge 318 of the attachment portion 308 may include a single curve. The single curve may extend fully or partially along the edge 318 of the attachment portion 308. The curve may curve inwardly, away from the end 310 as illustrated, or outwardly, towards the end 310 in other examples. In some examples the edge 318 of the attachment portion 308 may comprise other parts with curved and / or non-linear lines. In the example of Figure 7 the edge 318 of the attachment portion 308 is directed inwardly, towards the cover portion 306. In other examples the edge 318 of the attachment portion 308 may be directed outwardly, towards the end 310.

[0077] In other examples the edge 318 may comprise a plurality of straight lines with at least two different angles, for example a zig-zag line.

[0078] In the example of Figure 5B the edge 318 of the attachment portion 308 may thus be described as undulating within the transverse plane, the undulation defining sections of the edge 318 of the attachment portion 308 which underlie the cantilevered support 218 and sections of the edge 318 which do not underlie the cantilevered support 218, thus the undulation or undulations passing either side of a virtual line aligned with the root of the cantilevered support 218 which adjoins the beam 216. As such, the undulations might be considered to comprise a series of curves which are herein described as a wavy line with reference to Figure 5B. In other examples the undulations may comprise zig-zags, triangles, steps, castellations or square-wave features, in which the form of the undulation is sufficient to ensure sections of the edge 318 of the attachment portion 308 underlie the cantilevered support 218 whilst other sections of the edge 318 do not underlie the cantilevered support 218. The amplitude of such undulations may vary along the edge 318. The type of undulations may vary along the edge 318; that is the series of curves which comprise the undulations may comprise different forms of curve. An undulation may comprise a single curve such as that which will be described with reference to Figure 7. It will be understood that an undulation comprises at least one peak 314 and / or at least one trough 316, and that a series of undulations comprise a succession of peaks 314 alternating with a succession of troughs 316 as illustrated in Figure 5B. Furthermore, it will be understood that since the undulating edge at least partially underlies the cantilevered support 218 that in some examples the undulating edge completely underlies the cantilevered support 218.

[0079] The non-linear edge 318 of the attachment portion 308 improves the support provided to the cantilevered support 218 by the base plate 302. In particular, the base plate 302 itself is stiffened by forming the non-linear profile of the transition portion 312. Additionally, the limit of the contact between the attachment portion 308 and the cantilevered support 218 along the edge 318 is not a straight line, so there is not bending of the cantilevered support 218 about a straight line. In particular, the cantilevered support 218 bears the weight of the battery cell (e.g. cell 206 as in Figure 3) so is subject to a bending load acting towards the base plate 302, and the cantilevered support 218 is supported by the underlying attachment portion 308 that is in contact with the cantilevered support 218. The non-linear edge 318 of the attachment portion 308 at least partly underlying the cantilevered support 218 avoids any straight line about which this bending load acts on the cantilevered support 218, and therefore reduces the bending deflection imparted on the cantilevered support 218. For an edge 318 comprising a plurality of straight lines in the form of a zig-zag line then it is likewise true that the nonlinear edge as a whole similarly avoids having a straight line about which this bending load acts on the cantilevered support 218. Accordingly, it may be possible to use thinner and / or lighter materials for the end section 212 (in particular the cantilevered support 218), and the base plate 302 while still adequately supporting the battery cell (e.g. cell 206 as in Figure 3) within the vehicle battery assembly (e.g. assembly 200 as in Figure 3).

[0080] In simple mechanical theory, a cantilever beam may be depicted as supporting a load at some point along the length of the cantilever such that the load applied is at a given distance from the root of the cantilever. It is a well understood principle that the magnitude of peak bending moment is proportional to the said distance from the root of the cantilever. Another well understood principle is that the peak bending moment occurs at the root of the cantilever. When these principles are applied to the present invention then the applied load is represented by the weight of the battery cell or cells 206 and the effective position of the root of the cantilever is represented by the non-linear edge 318 of the attachment portion 308 which provides the support to the cantilever. The said distance is a length along the cantilevered support 218 extending in the second direction perpendicularly away from the beam 216 with the said distance being that length of cantilevered support 218 between the effective position of the root of the cantilever to the point of contact with the battery cell 208. Thus, as will be understood by comparing Figures 5A and 6A, where there is a peak 314 in the edge 318 the cantilevered support 218 extending beyond the edge 318 is of a shorter distance than where there is a trough 316 in the edge 318.

[0081] Accordingly, in this invention the effective position of the root of the cantilever in the second direction varies along the length of the cantilevered support 218 in the first direction according to the non-linearity of the edge 318. Consequently not only does the said distance vary, but also the effective position of the root of the cantilever varies rather than being along a single straight line. Consequently, the magnitude of the peak bending moment also varies along the cantilevered support 218 in the first direction. Furthermore, because the effective position of the root varies, then the position of the peak bending moment varies. That is, the position of the peak bending moment is distributed in the second direction along the length of the cantilevered support 218 rather than being focussed upon a line which is straight in the first direction. It will be appreciated that by distributing the position of peak bending moment along the length of the cantilevered support 218 the invention avoids creating a discrete line of weakness in the first direction of the structure of the vehicle battery assembly 200. Accordingly, it may be possible to use thinner and / or lighter materials for the battery frame 208 (e.g., an end section 212), and / or for the cantilevered support 218, and / or the base plate 302 while still providing support to the battery cell or cells 206 within the vehicle battery assembly 200.

[0082] In the illustrated example the transition portion 312 has an even width in the transverse plane (e.g. plane 220 in Figure 3). That is, a width of the transition portion 312 between the edge 318 of the attachment portion 308 and the cover portion 306 is substantially even. In other examples, the transition portion 312 may have a varying width in the transverse plane (e.g. the plane 220 as in Figure 3).

[0083] In examples the inner panel 304 is attached to the top side of the cantilevered support 218, on the side opposite the base plate 302. The inner panel 304 may be adhered and / or welded and / or rivetted to the cantilevered support 218. In examples, rivets or spot welds join the inner panel 304 to the cantilevered support 218 in positions aligned with the troughs 316 in the edge 318 of the attachment portion 308 so that the rivets or spot welds are provided in locations where the base plate 302 is spaced from the underside of the cantilevered support 218. In the example shown in Figure 5C the locations of a line of rivets 31 1 which secure the inner panel 304 to the cantilevered support 218 is shown in relation to the peaks 314 and troughs 316 of the edge of the attachment portion 308 of the base plate 302 of Figure 5B. The rivets are distributed along a line extending in the first direction, so that they are positioned along the cantilevered support 218 in the first direction. The rivets are spaced apart so as to align with the troughs 316 to ensure there is room for the rivets to protrude on the underside of the cantilevered support 218. Due to the smaller radius of the peaks 314 compared to the troughs 316, the peaks 314 are narrower than the troughs 316, meaning that the peaks 314 are able to extend along the length of the cantilever support 218 in the second direction between the line of rivets whilst the spacing of the rivets is not greatly increased to accommodate the width of the said peaks 314. In this way it is possible to optimise the stiffness of the attachment of the inner panel 304 to the cantilevered support 218 whilst also optimising the support provided to the cantilevered support 218 by the base plate 302.

[0084] The end of the inner panel 304 may also be adhered to the top side of the cantilevered support 218.

[0085] 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

CLAIMS1. A vehicle battery assembly for supporting a battery cell, wherein the vehicle battery assembly comprises: a base plate; and a battery frame, the battery frame comprising a cantilevered support extending in a transverse plane for supporting the battery cell in the vehicle battery assembly, wherein the base plate comprises an attachment portion attached to the battery frame, a cover portion offset from the attachment portion in a direction perpendicular to the transverse plane, and a transition portion joining an edge of the attachment portion to the cover portion, wherein the edge of the attachment portion is nonlinear in the transverse plane and positioned to at least partially underlie the cantilevered support when the attachment portion is attached to the battery frame.

2. The vehicle battery assembly of claim 1 , wherein the edge of the attachment portion is curved, wavy, or zig-zag.

3. The vehicle battery assembly of claim 1 or claim 2, wherein the base plate comprises an end and the attachment portion extends between the edge and the end.

4. The vehicle battery assembly of claim 3, wherein the attachment portion is planar between the edge and the end.

5. The vehicle battery assembly of any previous claim, wherein the edge of the attachment portion of the base plate completely underlies the cantilevered support.

6. The vehicle battery assembly of any previous claim, comprising an end section, wherein the cantilevered support extends from the end section, and wherein the attachment portion of the base plate is welded to the end section.

7. The vehicle battery assembly of claim 6, wherein the base plate comprises an end and the attachment portion extends between the edge and the end, and wherein the end of the base plate is welded to the end section.

8. The vehicle battery assembly of any previous claim, comprising an inner panel overlying the base plate, the inner panel comprising an end received on the cantilevered support on an opposite side to the base plate.

9. The vehicle battery assembly of claim 8, wherein the end of the inner panel is attached to the cantilevered support.

10. The vehicle battery assembly of claim 9 where dependent on claim 2, wherein the edge of the attachment portion is wavy in the form of a plurality of peaks and a plurality of troughs, the peaks having a smaller radius than the troughs, and wherein the inner panel is attached to the cantilevered support by means of rivets, and the rivets are aligned with troughs so as to avoid contact with the base plate.11 . The vehicle battery assembly of any previous claim, comprising a beam having a bottom surface, and wherein the cantilevered support extends from the beam in the transverse direction parallel to the bottom surface of the beam.

12. The vehicle battery assembly of claim 11 , wherein the attachment portion of the base plate is attached to the bottom surface of the beam.

13. The vehicle battery assembly of claim 11 or claim 12, wherein the edge of the attachment portion underlies the bottom surface and the cantilevered support of the beam.

14. A vehicle battery assembly of any previous claim comprising one or more battery cells supported on the cantilevered support.

15. A vehicle comprising the vehicle battery assembly of any previous claim.

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