Bus bar interconnect for battery pack

Abstract

A bus bar interconnect (100) for electrically connecting cell terminals (24, 26) of battery cells (20) in a battery pack (10) comprises a plurality of bus bars (200) arranged in an array having a plurality of rows and a plurality of columns (206) of bus bars (200). Each bus bar comprises a first mating end (215) for mating with a corresponding cell terminal of a corresponding battery cell (20) and a second mating end (217) for mating with an adjacent cell terminal of an adjacent corresponding battery cell (20). A bus bar (200) electrically connects battery cells (20) in a battery pack (10). The bus bar interconnect (100) includes a bus bar carrier (110) that holds each bus bar (200) in the array. The bus bar carrier (110) includes a frame member (122) that maintains a relative position of the bus bars (200). The frame member (122) is a structural foam element.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of Indian Application No. 202441005119, filed on January 25, 2024, the subject matter of which is incorporated herein by reference in its entirety. Technical field

[0003] The subject matter herein generally relates to battery packs, such as battery packs for electric vehicles. Background art

[0004] Electric vehicles include a battery system that includes a battery pack having a large number of battery cells. Typical battery systems require connection solutions to transfer / distribute power between groups of battery cells and have provisions for sensing battery parameters such as voltage and temperature. For power transfer, busbars (aluminum or copper) are typically welded to cell terminals in series and / or parallel electrical configurations. With the proliferation of electric vehicle applications, the indirect cost (overhead cost$ / kWh) of components is carefully examined, and there is a desire to minimize costs, for example, by minimizing the number of part items and the number of parts. For the battery systems of electric vehicles, the battery cell stack size is very large. Generally, the assembly of the battery system requires many parts that are individually assembled to the respective cell terminals, which is time - consuming and increases the cost of the assembly process. Some battery systems include injection - molded covers for the battery cells that hold the busbars. However, as the size of the battery pack increases, the size of the injection - molded cover has limitations due to the molding process. For example, the sub - component size is too large for conventional injection - molding processes. Additionally, the cycle time requirement (i.e., the takt time) must be reduced to meet greater production volumes. To reduce capital, tooling, and part costs as well as changeover costs, it is highly desirable to simplify the process whenever possible. A sustainable process and supply chain are also needed.

[0005] There is still a need for a method for assembling a battery pack in a cost - effective and reliable manner, such as for an electric vehicle. Summary of the invention

[0006] In one embodiment, a busbar interconnect for electrically connecting cell terminals of battery cells in a battery pack is provided. The busbar interconnect includes a plurality of busbars arranged in an array having multiple rows and multiple columns of busbars. Each busbar includes a first mating end for mating with a corresponding cell terminal of a corresponding battery cell and a second mating end for mating with an adjacent cell terminal of an adjacent corresponding battery cell. The busbars electrically connect the battery cells in the battery pack. The busbar interconnect includes a busbar carrier for holding each busbar in the array. The busbar carrier includes a frame member that holds the relative positions of the busbars. The frame member is a structural foam element. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention will be described by way of example with reference to the accompanying drawings, in which:

[0008] Figure 1 is a perspective view of a battery pack including a bus bar interconnect according to an exemplary embodiment.

[0009] Figure 2 shows a bus bar array according to an exemplary embodiment.

[0010] Figure 3 shows an upper grid of a bus bar carrier according to an exemplary embodiment.

[0011] Figure 4 is a cross-sectional view of a part of the upper grid according to an exemplary embodiment.

[0012] Figure 5 shows a lower grid of a bus bar carrier according to an exemplary embodiment.

[0013] Figure 6 is a cross-sectional view of a part of the lower grid according to an exemplary embodiment.

[0014] Figure 7 is a flow chart showing a method of assembling a battery pack according to an exemplary embodiment.

[0015] Figure 8 is a top view of a part of a bus bar interconnect during an assembly stage according to an exemplary embodiment.

[0016] Figure 9 is a top view of a part of a bus bar interconnect during assembly according to an exemplary embodiment.

[0017] Figure 10 is a top perspective view of a part of a bus bar interconnect during an assembly stage according to an exemplary embodiment, showing the upper grid ready to be coupled to the lower grid and the bus bar.

[0018] Figure 11 is a top perspective view of a part of a bus bar interconnect during an assembly stage according to an exemplary embodiment, showing the upper grid coupled to the lower grid and the bus bar.

[0019] Figure 12 is a top view of a part of a bus bar interconnect, showing the bus bar carrier holding the bus bar. DETAILED DESCRIPTION

[0020] Figure 1is a perspective view of a battery pack 10 including a bus bar interconnect 100 according to an exemplary embodiment. The battery pack 10 can be a battery pack for a vehicle, such as an electric vehicle. However, in alternative embodiments, the battery pack 10 can be used in other applications. In the exemplary embodiment, the battery pack 10 is a high-voltage battery pack. For example, the battery pack 10 can be a 400V or 800V battery pack. The bus bar interconnect 100 is used to electrically connect an array of battery cells 20 of the battery pack 10. For example, the bus bar interconnect 100 can connect the battery cells 20 in series and / or in parallel.

[0021] The battery cells 20 can be held in a battery pack housing 12. The battery pack 10 includes a positive battery interconnect terminal 14 and a negative battery interconnect terminal 16. The battery interconnect terminals 14, 16 form the main battery terminals of the battery pack 10, for example for connection to a charging system and / or a load, such as an electric motor.

[0022] Each battery cell 20 includes a cell housing 22, a first cell terminal 24, and a second cell terminal 26. In various embodiments, the battery cell 20 can be a prismatic battery cell. The first cell terminal 24 and the second cell terminal 26 can be a cathode terminal and an anode terminal. In the exemplary embodiment, the battery cell 20 is rectangular and arranged in a stacked configuration. For example, the battery cells 20 can be stacked in rows and columns of battery cells 20 in an array. The array can have a large surface area, for example greater than two square meters (2m 2 or more). Adjacent battery cells 20 in a row are interconnected by the bus bar interconnect 100. Adjacent rows of battery cells 20 are interconnected by the bus bar interconnect 100. For example, end battery cells 20 can be connected row to row.

[0023] The bus bar interconnect 100 includes a bus bar carrier 110 that holds a plurality of bus bars 200. The bus bar carrier 110 holds the bus bars 200 in relative positions for mating with the cell terminals 24, 26 of corresponding battery cells 20. The bus bars 200 electrically connect adjacent battery cells 20, such as in series and / or in parallel. The bus bar carrier 110 integrates all the bus bars 200 into a single unit for mounting to an array of battery cells 20. In an exemplary embodiment, the bus bar carrier 110 is a structural foam frame that holds the bus bars 200. The bus bar carrier 110 is manufactured by a structural foam molding process. The structural foam is a porous structure, such as a microcellular structure. In one exemplary embodiment, the structural foam has a low density microcellular core and a high density outer skin. The structural foam is rigid and maintains its shape to hold the bus bars 200 in relative positions for mounting to the battery cells 20. The bus bar carrier 110 is made by a low pressure structural foam process. The bus bar carrier 110 is made of a polymeric material, such as a thermosetting material or a thermoplastic material, where an inert gas, such as nitrogen, is injected into the mold during the forming process. The gas is injected into the mold together with the resin material to foam the plastic internally. For environmental sustainability, the lattice frame can be made with up to 100% regrind / recycled plastic material. Chemical blowing agents can be used to form the structural foam. The structural foam has a high strength-to-weight ratio, such as a higher strength-to-weight ratio compared to injection molded parts.

[0024] In an exemplary embodiment, the bus bar carrier 110 is made of two structural foam pieces, such as an upper lattice 120 and a lower lattice 160, which are joined together to capture the bus bars 200 therebetween. For example, the bus bars 200 can be stacked between the upper lattice 120 and the lower lattice 160. In an exemplary embodiment, the upper lattice 120 and the lower lattice 160 are the same. For example, the upper lattice 120 and the lower lattice 160 can be made from the same mold. The upper lattice 120 and the lower lattice 160 can be the same structural foam molded structure that is inverted 180° on opposite sides of an array of bus bars 200. However, in alternative embodiments, the upper lattice 120 and the lower lattice 160 can be different and molded from different molds. In an exemplary embodiment, the bus bar carrier 110 holds all the bus bars 200 for the battery pack 10 to reduce the number of parts items for final assembly into the battery pack 10. For example, a single bus bar interconnect 100 is assembled into the battery pack 10. The bus bar carrier 110 is used to position all the bus bars 200 for electrical connection to the cell terminals 24, 26 of the battery cells 20. The structural foam bus bar carrier 110 has an excellent stiffness-to-weight ratio. In an exemplary embodiment, the structural foam bus bar carrier 110 serves as a structural member in the battery pack 10 to resist torsion and z-displacement of the components of the battery pack, which improves safety and durability while eliminating the need for other mechanical components.

[0025] Figure 2 An array 202 of busbars 200 according to an exemplary embodiment is shown. The busbars 200 are arranged in rows 204 and columns 206 in the array 202. The arrangement of the busbars 200 corresponds to the arrangement of the battery cells 20 to connect to the corresponding cell terminals 24, 26.

[0026] Each busbar 200 includes a metal plate 210 having a body 212, a first mating pad 214 at a first mating end 215, and a second mating pad 216 at a second mating end 217. The first mating pad 214 is configured to connect to a cell terminal 24 of one of the battery cells 20. The second mating pad 216 is configured to connect to the cell terminal 26 of an adjacent battery cell 20. The busbar 200 electrically connects adjacent battery cells 20. The mating pads 214, 216 may include openings 218 therethrough, for example, for positioning the busbar 200 relative to the cell terminals 24, 26. The openings 218 can be used for pick-and-place operations.

[0027] In an exemplary embodiment, each busbar 200 is generally rectangular. For example, the busbar 200 includes a first end 220, a second end 222, a first side 224, and a second side 226. The busbar 200 may be elongate, for example, having ends 220, 222 that are longer than the sides 224, 226. In an exemplary embodiment, the busbar is planar overall. For example, the first mating pad 214 and the second mating pad 216 may be coplanar. The busbar 200 may include mounting features for mounting the busbar 200 to a busbar carrier 110, such as mounting tabs, posts, brackets, clips, notches, openings, etc.

[0028] In an exemplary embodiment, the bus bars 200 are arranged in bus bar strips 230. For example, a plurality of bus bars 200 can be stamped from a common sheet of material and arranged in strip form. In the illustrated embodiment, seven bus bar strips 230 are provided. In alternative embodiments, more or fewer bus bar strips 230 can be provided. In the illustrated embodiment, twenty bus bars 200 are provided in the bus bar strips 230. In alternative embodiments, more or fewer bus bars 200 can be provided in each bus bar strip 230. Different bus bar strips 230 can have different numbers of bus bars 200. In an exemplary embodiment, the connecting links 232 connect the bus bars 200 in the bus bar strips 230. The connecting links 232 mechanically fix the bus bars 200 relative to each other, for example controlling the spacing between the bus bars 200. The connecting links 232 are thin strips. Optionally, a single connecting link 232 can be located between adjacent bus bars 200. However, in alternative embodiments, multiple connecting links 232 can extend between adjacent bus bars 200. The connecting links 232 are sacrificial and are configured to be removed, for example by stamping, punching, or cutting processes, to individualize and electrically isolate the bus bars 200 from each other for connection to different battery cells 20.

[0029] In the illustrated embodiment, the connecting links 232 extend between the bodies 212 of adjacent bus bars 200 in the bus bar strips 230. The connecting links 232 can additionally or alternatively extend between mating pads 214, 216 on the sides 224, 226 of adjacent bus bars 200. In the illustrated embodiment, the bus bar strips 230 are arranged in columns. For example, the connecting links 232 connect all of the bus bars 200 within each column 206 together. In alternative embodiments, the bus bar strips 230 can be arranged in rows. For example, the connecting links 232 can connect all of the bus bars 200 within each row 204 together. In other embodiments, the connecting links 232 can be arranged in columns and rows. For example, all of the bus bars 200 in the array 202 can be stamped from a single sheet.

[0030] In an exemplary embodiment, the bus bar 200 includes an external bus bar 240 and an internal bus bar 242. The external bus bar 240 is disposed along opposite sides (e.g., the right and left sides) of the bus bar array 202. The external bus bar 240 is for connecting between battery cells 20 in two different rows. The internal bus bar 242 extends between the external bus bars 240. The internal bus bar 242 is for connecting adjacent battery cells 20 within the same column. The external bus bar 240 is oriented perpendicular to the internal bus bar 242. For example, the internal bus bar 242 is longitudinally oriented and the external bus bar 240 is transversely oriented. In alternative embodiments, other orientations are possible. In the illustrated embodiment, five internal bus bar strips 242 are disposed between the external bus bar strips 240. In alternative embodiments, a greater or lesser number of internal bus bars 242 may be provided. In the illustrated embodiment, the connection links 232 connecting the external bus bars 240 are different from the connection links 232 connecting the internal bus bars 242. For example, the inner connection links extend between the bodies 212, while the outer connection links extend between the mating pads 214, 216. In the illustrated embodiment, two outer connection links are provided between adjacent external bus bars 240, as opposed to a single inner connection link between adjacent internal bus bars 242.

[0031] Figure 3 The upper grid 120 of the bus bar carrier 110 according to an exemplary embodiment is shown. Figure 4 is a cross-sectional view of a part of the upper grid 120 according to an exemplary embodiment.

[0032] The upper grid 120 includes a frame member 122 configured to couple to the bus bar 200 to hold the relative positions of the bus bar 200. The frame member 122 is a structural foam element 150. The frame member 122 includes an outer frame member 130 and an inner frame member 140. The outer frame member 130 surrounds the perimeter of the upper grid 120, and the inner frame member 140 spans across the interior of the upper grid 120 to interface with the bus bar 200. In the illustrated embodiment, the outer frame member 130 completely surrounds the perimeter. The outer frame member 130 includes a first end member 132, a second end member 134, a first side member 136, and a second side member 138. The side members 136, 138 extend between the end members 132, 134. Optionally, the upper grid 120 is elongated, where the side members 136, 138 are longer in the longitudinal direction than the end members 132, 134. The end members 132, 134 may be perpendicular to the side members 136, 138 in the transverse direction. In alternative embodiments, more or fewer members may be provided to change the shape of the outer perimeter and the number of sides of the upper grid 120.

[0033] The inner frame member 140 extends between the outer frame members 130. For example, the inner frame member 140 includes longitudinal elements 142 and transverse elements 144. The longitudinal elements 142 longitudinally span the grid 120 between the opposing end members 132, 134. The longitudinal elements 142 and / or the transverse elements 144 can be used to support portions of the bus bar 200. The longitudinal elements 142 can be oriented generally parallel to the side members 136, 138. The transverse elements 144 transversely span the grid 120 between the opposing side members 136, 138. The transverse elements 144 can be oriented generally parallel to the end members 132, 134. The transverse elements 144 interconnect the longitudinal elements 142 to provide support for the longitudinal elements 142 and vice versa. In an exemplary embodiment, the inner frame member 140 is integrally formed with the outer frame member 130. For example, during a structural foam molding process, the inner frame member 140 is formed together with the outer frame member 130. The upper grid 120 forms an integral unitary structural foam structure.

[0034] In an exemplary embodiment, the upper grid 120 includes a plurality of nodes 146. The nodes 146 can be disposed at intersections of the longitudinal elements 142 and the transverse elements 144. The nodes 146 can be disposed at locations of the bus bar 200. The nodes 146 can be used to support portions of the bus bar 200. In an exemplary embodiment, the nodes 146 include openings 148. Each node 146 includes a ring 149 surrounding the opening 148. The opening 148 is configured to be aligned with a corresponding connecting link 232. In an exemplary embodiment, the connecting link 232 can be removed by stamping or cutting through the opening 148. In other embodiments, the connecting link 232 can be located external to the node 146, and the stamping or cutting can occur external to the node 146, such as along the outer surface of the frame member 122 or even away from the frame member 122.

[0035] Each frame member 122 includes a structural foam element 150. The structural foam element 150 is manufactured by a structural foaming process. The structural foam element 150 of the frame member 122 has a honeycomb-like microporous internal core structure. For example, each frame member 122 includes a foam core 152( Figure 4 ) and a skin 154 surrounding the foam core 152. The skin 154 has a higher density than the foam core 152. The foam core 152 includes cavities or holes 156 that can be filled with air. The skin 154 can be solid, for example, without air cavities. The skin 154 can be relatively thin compared to the foam core 152.

[0036] In an exemplary embodiment, the upper grid 120 includes upper alignment features 124 for aligning the upper grid 120 relative to the lower grid 160. The upper alignment features 124 may include tabs, posts, protrusions, grooves, slots, openings, or other types of alignment features. The upper alignment features 124 may be complementary to corresponding alignment features of the lower grid 160 to position the upper grid 120 relative to the lower grid 160.

[0037] In an exemplary embodiment, the upper grid 120 includes upper fixing features 126 for fixing the upper grid 120 to the lower grid 160. The upper fixing features 126 may include tabs, bosses, latches, clips, fasteners, or other types of fixing features. The upper fixing features 126 may be complementary to corresponding fixing features of the lower grid 160 to fix the upper grid 120 to the lower grid 160.

[0038] Figure 5 The lower grid 160 of the bus bar carrier 110 according to an exemplary embodiment is shown. Figure 6 It is a cross-sectional view of a part of the lower grid 160 according to an exemplary embodiment.

[0039] The lower grid 160 includes a frame member 162 configured to couple to the bus bar 200 to hold the relative position of the bus bar 200. The frame member 162 is a structural foam element 190. The frame member 162 includes an outer frame member 170 and an inner frame member 180. The outer frame member 170 surrounds the perimeter of the lower grid 160, and the inner frame member 180 spans the interior of the lower grid 160 to interface with the bus bar 200. In the illustrated embodiment, the outer frame member 170 completely encloses the perimeter. The outer frame member 170 includes a first end member 172, a second end member 174, a first side member 176, and a second side member 178. The side members 176, 178 extend between the end members 172, 174. Optionally, the lower grid 160 is elongated, where the side members 176, 178 are longer in the longitudinal direction than the end members 172, 174. The end members 172, 174 may be perpendicular to the side members 176, 178 in the transverse direction. In alternative embodiments, more or fewer members may be provided to change the shape of the outer perimeter and the number of sides of the lower grid 160.

[0040] The inner frame member 180 extends between the outer frame members 170. For example, the inner frame member 180 includes longitudinal elements 182 and transverse elements 184. The longitudinal elements 182 extend longitudinally across the grid 160 between the opposing end members 172, 174. The longitudinal elements 182 and / or the transverse elements 184 can be used to support portions of the bus bar 200. The longitudinal elements 182 can be oriented substantially parallel to the side members 176, 178. The transverse elements 184 extend transversely across the lower grid 160 between the opposing side members 176, 178. The transverse elements 184 can be oriented substantially parallel to the end members 172, 174. The transverse elements 184 interconnect the longitudinal elements 182 to provide support for the longitudinal elements 182, and vice versa. In an exemplary embodiment, the inner frame member 180 is integrally formed with the outer frame member 170. For example, during a structural foam molding process, the inner frame member 180 is formed together with the outer frame member 170. The lower grid 160 forms a monolithic unitary structural foam structure.

[0041] In an exemplary embodiment, the lower grid 160 includes a plurality of nodes 186. The nodes 186 can be disposed at intersections of the longitudinal elements 182 and the transverse elements 184. The nodes 186 can be disposed at the location of the bus bar 200. The nodes 186 can be used to support portions of the bus bar 200. In an exemplary embodiment, the nodes 186 include openings 188. Each node 186 includes a ring 189 around the opening 188. The opening 188 is configured to align with a corresponding connecting link 232. In an exemplary embodiment, the connecting link 232 can be removed by stamping or cutting the connecting link 232 through the opening 188. In other embodiments, the connecting link 232 can be located outside the node 186, and the stamping or cutting can occur outside the node 186, such as along the outer surface of the frame member 162 or even away from the frame member 162.

[0042] Each frame member 162 includes a structural foam element 190. The structural foam element 190 is manufactured by a structural foaming process. The structural foam element 190 of the frame member 162 has a honeycomb-like porous core structure. For example, each frame member 162 includes a foam core 192( Figure 6 ) and a skin 194 surrounding the foam core 192. The skin 194 has a higher density than the foam core 192. The foam core 192 includes cavities or pores 196 that can be filled with air. The skin 194 can be solid, for example, without air cavities. The skin 194 can be relatively thin compared to the foam core 192.

[0043] In an exemplary embodiment, the lower grid 160 includes lower alignment features 166 for aligning the lower grid 160 relative to the upper grid 120. The lower alignment features 166 may include tabs, posts, protrusions, grooves, slots, openings, or other types of alignment features. The lower alignment features 166 may be complementary to the upper alignment features 124 of the upper grid 120 to position the lower grid 160 relative to the upper grid 120.

[0044] In an exemplary embodiment, the lower grid 160 includes lower fixing features 164 for fixing the lower grid 160 to the upper grid 120. The lower fixing features 164 may include tabs, bosses, latches, clips, fasteners, or other types of fixing features. The lower fixing features 164 may be complementary to the corresponding upper fixing features 126 of the upper grid 120 to fix the lower grid 160 to the upper grid 120.

[0045] Figure 7 is a flowchart 700 showing a method of assembling a battery pack according to an exemplary embodiment. At 702, the method includes the step of structurally foam molding the lower grid. At 704, the method includes the step of structurally foam molding the upper grid. The foam molding steps may be performed sequentially or simultaneously, for example, using a two-cavity mold. In various embodiments, the lower grid and the upper grid may be the same structure, so the same foam molding steps may be used to form either of the grid frames, for example, using the same tooling. For example, the upper grid and the lower grid may be the same structurally foam molded structure inverted 180° on opposite sides of the busbar array. The structural foam molding process includes molding frame members into a grid frame such as including longitudinal members and transverse members. The structural foam molding process includes forming a skin surrounding a foam core. The structural foam molding process includes adding an inert gas (such as nitrogen) to a mold having a thermoplastic or thermosetting material. The structural foam molding process may include adding a chemical blowing agent together with the thermoplastic or thermosetting material to the mold.

[0046] At 706, the method includes forming the busbars. The busbars may be formed by a stamping or laser cutting process. In an exemplary embodiment, the busbars are formed as busbar strips having connecting links between the respective busbars. The connecting links maintain the relative positions of the busbars.

[0047] At 708, the method includes the optional step of forming a sensing harness. The sensing harness includes a plurality of sensors, such as temperature sensors, voltage sensors, or other types of sensors. The sensors are connected by a circuit. The circuit may be a flat flexible circuit, a flexible printed circuit, or a wire harness.

[0048] At 710, the method includes mounting the busbars on the lower grid. The busbar strips can be inserted into the lower grid. By assembling the busbars in strip form, the number of components is greatly reduced during assembly, resulting in faster cycle times and easier handling. The frame members of the lower grid support the busbars. In an exemplary embodiment, the connecting links are aligned with the openings in the nodes of the frame of the lower grid for later access and removal.

[0049] At 712, the method includes the optional step of mounting the sensing harness on the busbars. The sensors can be coupled to the corresponding busbars. Optionally, each busbar can have a corresponding sensor associated therewith. The sensors can be soldered, welded, or otherwise mechanically joined or fastened to the busbars.

[0050] At 714, the method includes mounting the upper grid on the busbars and the lower grid. The upper grid is aligned with the lower grid through alignment features. The busbars and possibly optional sensing circuit components are captured between the upper grid and the lower grid. Optionally, the nodes of the upper grid can be aligned with the connecting links, for example, aligning the openings in the nodes with the connecting links for later removal. The upper grid can be fixed to the lower grid using, for example, fixing features.

[0051] At 716, the method includes disconnecting the bus connections of the busbars by removing the connecting links. The connecting links can be removed by stamping or cutting processes. The connecting links can be removed by laser cutting the connecting links. The connecting links are removed to individualize the busbars from each other and from the busbar strips. The connecting links are removed to electrically isolate the busbars from each other.

[0052] At 718, the method includes mounting the busbar interconnects on the battery cells of the battery pack. For example, the busbar carriers (upper grid and lower grid) are used to position all the busbars in alignment with the respective cell terminals of the battery cells to electrically connect the busbars to the battery cells. For example, the busbar carriers hold the busbars in position for laser welding to the cell terminals.

[0053] Figure 8 Is a top view of a portion of the busbar interconnect 100 during the assembly phase. Figure 8Shows a bus bar 200 mounted on the lower grid 160. In an exemplary embodiment, the bus bar 200 is mounted on the lower grid 160 as a bus bar strip 230, where the connecting link 232 holds the position of the bus bar 200 relative to each other within the bus bar strip 230. The frame member 162 of the lower grid 160 supports the bus bar 200. For example, the bus bar 200 is supported by the longitudinal element 182 and the transverse element 184. The frame member 162 may be located below the body 212 and / or the first mating pad 214 and / or the second mating pad 216 and / or the connecting link 232 of each bus bar 200. In an exemplary embodiment, the connecting link 232 is arranged at the node 186.

[0054] Figure 9 Is a top view during the assembly of a part of the bus bar interconnect 100. Figure 9 Shows the upper grid 120 coupled to the lower grid 160 and the bus bar 200. The bus bar 200 is captured between the upper grid 120 and the lower grid 160. For example, the frame member 122 of the upper grid 120 supports the bus bar 200. The frame member 122 may be aligned with the frame member 162 to capture the bus bar 200 between the frame member 122 and the frame member 162. The bus bar 200 may be supported by the longitudinal element 142 and / or the transverse element 144. For example, the frame member 122 may support the body 212 and / or the first mating pad 214 and / or the second mating pad 216 and / or the connecting link 232 of each bus bar 200. In an exemplary embodiment, the connecting link 232 is arranged at the node 146. For example, the connecting link 232 may be exposed in the opening 148 of the node 146, such as for later removal.

[0055] Figure 10 Is a top perspective view of a part of the bus bar interconnect 100 during the assembly phase, showing the upper grid 120 ready to be coupled to the lower grid 160 and the bus bar 200. Figure 11 Is a top perspective view of a part of the bus bar interconnect 100 during the assembly phase, showing the upper grid 120 coupled to the lower grid 160 and the bus bar 200. The upper grid 120 and the lower grid 160 form a rigid bus bar carrier 110 for supporting each of the bus bars 200 at a predetermined position to terminate at the cell terminals 24, 26 of the battery cell 20. In an exemplary embodiment, the mating pads 214, 216 of each bus bar 200 are stepped downward relative to the body 212 to position the mating interface at the mating ends 215, 217 at the bottom of the bus bar interconnect 100. For example, the mating ends 215, 217 may be positioned coplanar with the bottom surface of the lower grid 160 for connecting the bus bar 200 to the cell terminals 24, 26 of the battery cell 20.

[0056] During assembly, the alignment features 124 of the upper grid 120 are aligned with the alignment features 164 of the lower grid 160. The alignment features 124 mate with the alignment features 164 to properly orient the upper grid 120 relative to the lower grid 160. In an exemplary embodiment, the alignment features 124 include alignment posts and / or alignment openings, and the alignment features 164 include complementary alignment posts and / or alignment openings. For example, the alignment posts of the upper grid 120 are received in the alignment openings of the lower grid 160. Similarly, the alignment posts of the lower grid 160 are received in the alignment openings of the upper grid 120. Other types of alignment features may be used in alternative embodiments.

[0057] During assembly, the securing features 126 of the upper grid 120 are aligned with and coupled to the securing features 166 of the lower grid 160. The securing features 126 mate with the securing features 166 to secure the upper grid 120 to the lower grid 160. In an exemplary embodiment, the securing features 126 include securing bosses and / or securing latches, and the securing features 166 include complementary securing bosses and / or securing latches. For example, the securing latch of the upper grid 120 is latchably coupled to the securing boss of the lower grid 160. Similarly, the securing latch of the lower grid 160 is latchably coupled to the securing boss of the upper grid 120. Other types of securing features may be used in alternative embodiments.

[0058] After assembling the bus bar carrier 110, the connecting strip 232 between the bus bars 200 can be removed. For example, the connecting strip 232 can be punched, perforated or cut and removed from the bus bars 200. In various embodiments, the connecting strip 232 can be removed by a laser cutting process. The removal of the connecting strip 232 electrically isolates the bus bars 200 from each other. The bus bar carrier 110 securely holds the bus bars 200 in position relative to each other after the connecting strip 232 is removed.

[0059] Figure 12 is a top view of a portion of the bus bar interconnect 100, showing the bus bar carrier 110 holding the bus bars 200. The connecting strip 232 ( Figure 10 ) is removed in Figure 12 . The bus bars 200 are held by the frame members 122, 162 of the upper grid 120 and the lower grid 160.

[0060] The busbar interconnect 100 provides a large-format cell interconnect that is configured to be mounted as a single unit to a battery pack 10 (e.g., each cell 20). The busbar carrier 110 holds all the busbars 200 in place for termination to the cell terminals 24, 26 of each cell 20 of the battery pack 10. By holding all the busbars 200 for all the cells 20 to be assembled into the battery pack 10, the assembly process can be eliminated, such as for a conventional battery system where each busbar is assembled to the cells individually or in multiple strips through multiple assembly steps. The busbar interconnect 100 reduces the overall number of component items and the number of components handled during the assembly of the battery pack 10. The busbar carrier 110 can have a large format and surface area. For example, the structural foam process for manufacturing the lattice frame for the busbar carrier 110 enables a large footprint for the busbar carrier 110, especially compared to injection molded components. The busbar carrier 110 has a higher strength-to-weight ratio compared to comparable injection molded components. The lattice frame that supports the busbar carrier 110 can be manufactured in a low-pressure structural foam molding process, allowing the use of lower cost molds (e.g., aluminum molds compared to high-strength steel molds). The structural foam material for the lattice frame of the busbar carrier 110 is dimensionally stable and does not tend to warp, making assembly and termination to the cells simpler, faster, and less costly compared to conventional assembly processes. The structural foam material is more environmentally sustainable compared to conventional injection molded plastic components. For example, the structural foam material uses less plastic and can use recycled materials.

Claims

1. A busbar interconnect (100) for electrically connecting unit terminals (24, 26) of battery cells (20) in a battery pack (10), the busbar interconnect (100) comprising: A plurality of busbars (200) arranged in an array having a plurality of rows and a plurality of columns (206) of busbars (200), each busbar including a first mating end (215) for mating with a corresponding unit terminal of a corresponding battery cell (20) and a second mating end (217) for mating with an adjacent unit terminal of an adjacent corresponding battery cell (20), the busbars (200) electrically connecting the battery cells (20) in the battery pack (10); And A busbar carrier (110) that holds each of the busbars (200) in the array, the busbar carrier (110) including a frame member (122) that holds the relative positions of the busbars (200), the frame member (122) being a structural foam element.

2. The busbar interconnect (100) according to claim 1, wherein the frame member (122) has a honeycomb-like porous core structure.

3. The bus bar interconnecting member (100) according to claim 1, wherein, Each frame member includes a foam core (152) and a solid skin (154) surrounding the foam core (152).

4. The bus bar interconnect (100) according to claim 3, wherein, The skin (154) has a higher density than the foam core (152).

5. The bus bar interconnecting member (100) according to claim 1, wherein, The frame member (122) has a higher strength-to-weight ratio compared to equivalent injection-molded parts.

6. The bus bar interconnecting member (100) according to claim 1, wherein, The frame member (122) includes an outer frame member (130) surrounding the perimeter of the busbar carrier (110) and inner frame members (140, 180) spanning the interior of the busbar carrier (110) to interface with the busbars (200).

7. The bus bar interconnect (100) according to claim 6, wherein, The inner frame members (140, 180) include longitudinal elements (142) and transverse elements (144, 184) interconnecting the longitudinal elements (142).

8. The bus bar interconnect (100) according to claim 1, wherein, The frame member (122) includes nodes adjacent to the busbars (200) that support the busbars (200).

9. The bus bar interconnect (100) according to claim 8, wherein, The busbars (200) are stamped and formed in a busbar strip (230) having connecting links (232) that are stamped with the busbars (200) and extend between the busbars (200) to support the relative positions of the busbars (200), the nodes being located at the connecting links (232), wherein the connecting links (232) are removed after the busbars (200) are held by the busbar carrier (110) to electrically isolate the busbars (200) from each other.

10. The bus bar interconnecting member (100) according to claim 9, wherein, Each node includes a ring (149) surrounding an opening that aligns with a corresponding connecting link to permit removal of the connecting link through the opening.

11. The bus bar interconnect (100) according to claim 1, wherein, The frame member includes an upper frame member (122) and a lower frame member (162). The upper frame member is molded to form an upper grid (120), and the lower frame member is molded to form a lower grid (160). The upper grid (120) is coupled to the lower grid (160) to form the bus bar carrier (110), and the bus bar (200) is captured between the upper grid (120) and the lower grid (160).

12. The bus bar interconnect (100) according to claim 11, wherein, The upper grid (120) and the lower grid (160) are identical structural foam molded structures that are inverted 180° on opposite sides of an array of the bus bars (200).

13. The bus bar interconnect (100) according to claim 11, wherein, The upper grid (120) includes upper alignment features (126), and the lower grid (160) includes lower alignment features (166). The upper alignment features (126) mate with the lower alignment features (166) to position the upper grid (120) relative to the lower grid (160).

14. The bus bar interconnect (100) according to claim 1, further comprising a sensing harness having sensors coupled to the bus bars (200), and the bus bar carrier (110) supports the sensing harness.

15. A bus bar interconnect (100) for electrically connecting unit terminals (24, 26) of battery cells (20) in a battery pack (10), the bus bar interconnect (100) comprising: a plurality of bus bars (200) arranged in an array having a plurality of rows (204) and a plurality of columns (206) of the bus bars (200), each bus bar including a first mating end (215) for mating with a corresponding unit terminal of a corresponding battery cell (20) and a second mating end (217) for mating with an adjacent corresponding unit terminal of an adjacent corresponding battery cell (20), the bus bars (200) electrically connecting the battery cells (20) in the battery pack (10); and a bus bar carrier (110) holding each bus bar (200) in the array, the bus bar carrier (110) including an upper grid (120) and a lower grid (160), the upper grid (120) including an upper frame member (122), the lower grid (160) including a lower frame member (162), the upper grid (120) being coupled to the lower grid (160), the bus bars (200) being held between the upper grid (120) and the lower grid, and the upper frame member (122) and the lower frame member (162) being structural foam elements.

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