A busbar fixation assembly, and a vehicle

Abstract

A fixation assembly (1) for securing an electrical busbar (2) to at least one of a cooling plate (3) or housing, wherein the fixation assembly comprises: an electrical busbar (2); the cooling plate (3) having a recess (5) configured to receive a lower metal insert (6), and optionally a thermal interface material (TIM) layer (7), whereby at least a part of the lower metal insert being arranged in or on the cooling plate; an upper metal insert (8) extending through an opening (9) in the electrical busbar (2); and a fastening element (10) configured to engage the upper metal insert with the lower metal insert so as to clamp the busbar against the cooling plate, wherein a clamping force between the busbar and the cooling plate is transmitted through the upper and lower metal inserts.

Description

[0001] The disclosure relates generally to electrical power distribution and thermal management for high-current electrical conductors, and, more specifically, to a compact mechanical fixation assembly for securing an electrical busbar to at least one of a cooling plate or a housing while maintaining a thermal interface material (TIM) between the busbar and the cooling plate. In particular aspects, the disclosure relates to a busbar fixation assembly for use in a vehicle. The disclosure can be applied to any type of vehicle, including heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types. The disclosure can be applied to road vehicles including heavy duty trucks with fifth wheel trailers, in laden and unladen configurations. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle.BACKGROUND

[0002] Modem electrified powertrains and power electronics systems commonly include busbars that conduct high currents between cells, modules, contactors, fuses, capacitors, and semiconductor switching devices. To manage Joule heating, a busbar may be thermally coupled to a cooling plate or housing wall. Such coupling may be implemented using thermal interface materials (TIMs) to reduce thermal contact resistance and to accommodate surface roughness.

[0003] Conventional busbar-to-housing interface concepts may rely on plastic layers, insulating grommets, or plastic-supported fastening geometries to provide electrical insulation and mechanical fixation. Over time, plastic creep, plastic aging, and manufacturing tolerances can reduce or vary the clamping force applied to the busbar. Reduced or nonuniform clamping can degrade mechanical stability, allow loosening under vibration, and reduce TIM compression, thereby impairing thermal performance. Additionally, compact packaging constraints can limit available clearance for conventional fastening hardware and can complicate placement of TIM beneath the busbar.

[0004] According to a first aspect of the disclosure, a fixation assembly for securing an electrical busbar to at least one of a cooling plate or housing is provided. The fixation assembly comprises a busbar; a cooling plate having a recess configured to receive a lower metal insert, and optionally a thermal interface material (TIM) layer; an upper metal insert extending through an opening in the busbar; and a fastening element configured to engage the upper metal insert with the lower metal insert so as to clamp the busbar against the cooling plate, wherein a clamping force between the busbar and the cooling plate is transmitted through the upper and lower metal inserts.

[0005] A technical benefit may include maintaining a stable long-term clamping force for the busbar by transmitting the mechanical load through metal-to-metal elements rather than through plastic components susceptible to creep and aging. This can reduce loosening risk and improve robustness over the product lifetime.

[0006] Another technical benefit may include improved thermal coupling by enabling controlled and repeatable compression of a TIM layer beneath the busbar, thereby reducing thermal contact resistance and improving heat transfer to the cooling plate.

[0007] A further technical benefit may include enabling tighter and more compact packaging by positioning fixation hardware fully or partly beneath the busbar and by using a recess in the cooling plate to accommodate a lower metal insert and / or a TTM region, thereby improving clearance management relative to conventional externally protruding fixation geometries.

[0008] Optionally, in some examples, including in at least one preferred example, the fixation is substantially independent of plastic material tolerances, deformation, or aging.

[0009] Optionally, in some examples, including in at least one preferred example, a plastic layer surrounds at least part of the upper metal insert, the plastic layer providing electrical insulation without contributing to the mechanical fixation. A technical benefit may include achieving electrical isolation while keeping the clamp load path substantially independent of plastic deformation.

[0010] Optionally, in some examples, including in at least one preferred example, the TIM layer is positioned beneath the busbar and laterally adjacent to the lower metal insert, allowing thermal conduction. A technical benefit may include preserving an effective TIM contact region while still accommodating a compact recessed fixation geometry.

[0011] Optionally, in some examples, including in at least one preferred example, the fastening element comprises a nut located above the busbar. A technical benefit may include simplified assembly and serviceability using conventional tooling.

[0012] Optionally, in some examples, including in at least one preferred example, the upper metal insert comprises a cylindrical stud or shaft configured to pass through aligned openings in the busbar, the plastic layer, and the TIM layer, and the lower metal insert comprises a cup-shaped or T-shaped metallic element embedded in the cooling plate. A technical benefit may include improved pull-out resistance and robust load distribution while maintaining electrical insulation.

[0013] Optionally, in some examples, including in at least one preferred example, the fixation assembly is configured such that clearance variations or creep in the plastic layer do not alter the clamping force applied to the busbar. A technical benefit may include stable preload and consistent TIM compression over lifetime.

[0014] There is also provided a method for securing an electrical busbar to at least one of a cooling plate or housing using a fixation assembly, the method comprising: providing a cooling plate having a recess and a lower metal insert arranged in or on the cooling plate; arranging an optional thermal interface material (TIM) layer between the busbar and the cooling plate; positioning an upper metal insert through an opening in the busbar; engaging a fastening element with the upper metal insert and the lower metal insert to clamp the busbar against the cooling plate; and transmitting a clamping force through the upper and lower metal inserts.

[0015] In examples, the method maintains fixation substantially independent of plastic material tolerances, deformation, or aging.

[0016] There is also provided an electrical module comprising a fixation assembly according to any of the previously described examples, and a vehicle comprising such an electrical module.

[0017] The disclosure can be applied to any type of electrical system including battery packs, inverters, DC / DC converters, charging units, and other power electronics assemblies requiring busbars with controlled thermal conduction to a cooled structure. Although the disclosure may be described with respect to a particular assembly, the disclosure is not restricted to any particular assembly.

[0018] Examples are described in more detail below with reference to the appended drawings.

[0019] FIG. 1 shows a schematic cross-sectional view and a perspective view of an exemplary fixation assembly for securing an electrical busbar to a cooling plate with an optional thermal interface material (TIM) layer according to an example.

[0020] FIG. 2 is a flow-chart of an exemplary method according to an example.DETAILED DESCRIPTION

[0021] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0022] Although particular geometries, insert shapes, and assembly sequences are described, the disclosure is not limited to any particular configuration unless explicitly recited in the claims.

[0023] FIG. 1 shows a fixation assembly 1 for securing an electrical busbar 2 to at least one of a cooling plate 3 or housing. The cooling plate 3 includes a recess 5 configured to receive a lower metal insert 6, and optionally a thermal interface material (TIM) layer 7. At least a part of the lower metal insert 6 is arranged in or on the cooling plate 3.

[0024] The fixation assembly 1 further comprises an upper metal insert 8 extending through an opening 9 in the electrical busbar 2. A fastening element 10 is configured to engage the upper metal insert 8 with the lower metal insert 6 so as to clamp the electrical busbar 2 against the cooling plate 3. In operation, a clamping force between the electrical busbar 2 and the cooling plate 3 is transmitted through the upper metal insert 8 and the lower metal insert 6. In examples, the fixation is substantially independent of plastic material tolerances, deformation, or aging, because the principal clamp-load path is metal-to-metal via the inserts 8, 6 rather than via plastic components.

[0025] In the example of FIG. 1, a coordinate system is defined for ease of reference. The X-direction may correspond to a longitudinal direction for example along a main extension of the electrical busbar 2 or along a principal in-plane direction of the cooling plate 3. The Y-direction may correspond to a transverse in-plane direction of the electrical busbar 2, or the cooling plate 3, orthogonal to X. The Z-direction may correspond to a through-thickness direction normal to a main surface of the electrical busbar 2, or the cooling plate 3. In one example, the clamping force applied by the fastening element 10 acts substantially along the Z-direction, compressing the optional TIM layer 7 between the electrical busbar 2 and the cooling plate 3.

[0026] In one example, an optional plastic layer 11 surrounds at least part of the upper metal insert 8. The plastic layer 11 may be configured to provide electrical insulation for example to prevent electrical contact between the electrical busbar 2 and the upper metal insert 8, between the upper metal insert 8 and the lower metal insert 6 (as shown in Fig. 1), and / or other conductive parts without contributing to the mechanical fixation. In other words, the plastic layer 11 may electrically isolate while the clamping force is predominantly carried by the upper metal insert 8, the lower metal insert 6, and the fastening element 10.

[0027] In one example, the optional TIM layer 7 is positioned beneath the electrical busbar 2 and laterally adjacent (in the Χ / Ύ plane) to the lower metal insert 6, allowing thermal conduction from the electrical busbar 2 to the cooling plate 3 while keeping the fixation compact.

[0028] The recess 5 may be configured so that the lower metal insert 6 is at least partly located below a surface region of the cooling plate 3 supporting the electrical busbar 2, thereby enabling hidden or partially hidden fixation below the busbar footprint.

[0029] In one example, the fastening element 10 comprises a nut. The nut is located above the electrical busbar 2 (in the direction Z relative to the busbar / cooling plate interface.

[0030] The upper metal insert 8 may comprise a cylindrical stud or shaft configured to pass through the opening 9 in the electrical busbar 2. The upper metal insert 8 may in addition, or alternatively, be provide in the form of a cup-shaped or T-shaped metallic element, as shown in Fig. 1.

[0031] Moreover, as shown in Fig. 1, the lower metal insert 6 may comprise a cup-shaped or T-shaped metallic element embedded in the cooling plate 3, which can improve pull-out resistance and distribute loads into the cooling plate.

[0032] In one example, the fixation assembly 1 is configured such that clearance variations, manufacturing tolerances, and / or creep in the plastic layer 11 do not materially alter the clamping force applied to the electrical busbar 2, because the clamp-load path is determined primarily by the metallic interfaces of the upper metal insert 8, the lower metal insert 6, and the fastening element 10. This supports stable TIM compression and long-term robustness.

[0033] As illustrated in Fig. 1, the plastic layer 11 may typically extend beneath the TIM 7 to form a physical barrier. This design feature serves to protect against creepage and clearance-related insulation failures. In the context of electrical design, clearance refers to the shortest distance between two conductive elements measured through air, which may influence the risk of arcing under certain conditions. Creepage refers to the shortest distance along the surface of an insulating material between conductive parts, and is relevant for avoiding surface tracking in the presence of contaminants such as moisture or dust. By extending the plastic layer 11 under the TIM 7, the design supports compliance with applicable insulation distance guidelines and contributes to improved electrical isolation.

[0034] Example materials may be selected to meet electrical, thermal, and mechanical requirements. For example: the electrical busbar 2 may comprise copper, aluminum, or a copper alloy, optionally with a surface finish or plating such as tin, nickel, or silver for corrosion resistance and contact performance; the cooling plate 3 may comprise aluminum for example an extruded or machined aluminum cold plate, copper, or a thermally conductive housing material, optionally with internal coolant channels; the upper metal insert 8 and / or lower metal insert 6 may comprise steel, stainless steel, brass, or other metallic materials chosen for strength and corrosion performance, and may include coatings for example zinc, nickel, or passivation; the plastic layer 11 may comprise an electrically insulating polymer such as PA (polyamide), optionally glass-filled, PPS (polyphenylene sulfide), PBT, PEEK, or other high-temperature engineering plastics; the TIM layer 7 may comprise a silicone-based gap filler pad, a thermal grease, a phase change material, a graphite sheet, or other thermally conductive interface materials, optionally electrically insulating depending on system architecture.

[0035] Fig. 2 further shows an exemplary flowchart of a method 100 according to examples. The method 100 is implemented during manufacturing and / or service and is configured for securing the electrical busbar 2 to the cooling plate 3.

[0036] The method 100 comprises step S10 of providing the cooling plate 3 having the recess 5, and arranging the lower metal insert 6 in or on the cooling plate 3.

[0037] The method 100 comprises step S20 of arranging the optional TIM layer 7 between the electrical busbar 2 and the cooling plate 3 in a region configured for thermal conduction.

[0038] The method 100 comprises step S30 of positioning the electrical busbar 2 relative to the cooling plate 3 and inserting the upper metal insert 8 through the opening 9 in the electrical busbar 2.

[0039] The method 100 comprises step S40 of engaging the fastening element 10 with the upper metal insert 8 and the lower metal insert 6.

[0040] The method 100 comprises step S50 of tightening to generate a clamping force acting substantially along the Z-direction, clamping the electrical busbar 2 against the cooling plate 3, wherein the clamping force is transmitted through the upper and lower metal inserts 8, 6. In examples, the fixation is substantially independent of plastic material tolerances, deformation, or aging.

[0041] In some examples, the fixation assembly 1 is integrated in a vehicle electrical system, in particular in a vehicle such as a truck, bus, or other heavy-duty vehicle, although passenger cars and off-road vehicles are also contemplated. The fixation assembly 1 may be used to secure one or more electrical busbars 2 within a battery pack, power distribution unit, inverter, DC / DC converter, onboard charger, or other power electronics module installed in the vehicle.

[0042] In one example, the cooling plate 3 forms part of a battery pack housing or module housing and is thermally coupled to a vehicle cooling circuit. The cooling plate 3 may comprise internal coolant channels configured to circulate a liquid coolant, or may be thermally connected to a separate heat exchanger. The busbar 2 may electrically interconnect battery cells, battery modules, contactors, fuses, or terminals, while being thermally coupled to the cooling plate 3 via the optional TIM layer 7.

[0043] In one example, the fixation assembly 1 is arranged inside a sealed enclosure, such as a battery pack or power electronics housing, and is configured to withstand vehicle operating conditions including vibration, shock, temperature cycling, and long-term aging. By transmitting the clamping force through the upper and lower metal inserts 8, 6, the fixation assembly 1 maintains stable mechanical and thermal performance over the vehicle lifetime, even when plastic components are present for electrical insulation.

[0044] In one example, the fixation assembly 1 is oriented such that the Z-direction corresponds to a vertical direction in the vehicle when installed, while the X- and Y-directions correspond to longitudinal and transverse vehicle directions, respectively. In other examples, the fixation assembly 1 may be oriented differently depending on packaging constraints, and the coordinate system is used only for explanatory purposes.

[0045] In one example, multiple fixation assemblies 1 are used to secure a plurality of busbars 2 to a common cooling plate 3 within the same module. The fixation assemblies 1 may be distributed along the busbar length in the X-direction to ensure uniform clamping force, controlled TIM compression, and resistance to vibration-induced loosening.

[0046] The fixation assembly 1 may be assembled during module manufacturing and may remain in place throughout the service life of the vehicle. In some examples, the fastening element 10 is accessible from above the busbar 2 to facilitate assembly and service, while the lower metal insert 6 remains hidden within the cooling plate 3, contributing to compact packaging and improved clearance to covers or adjacent components.

[0047] The disclosed fixation assembly 1 provides improved long-term fixation robustness against plastic aging and tolerances, supports consistent TIM compression for thermal performance, and enables compact packaging of busbar-to-cooling-plate interfaces.

[0048] The term “busbar” encompasses any conductive bar, plate, laminated conductor, or stamped conductor configured to carry electrical current between components. The term “cooling plate” encompasses a cold plate, housing wall, heat spreader, or other thermally conductive structure configured to remove heat from the busbar. The term “thermal interface material (TIM)” encompasses thermally conductive pads, greases, phase change materials, gap fillers, and similar materials positioned between the busbar and the cooling plate to improve heat transfer.

[0049] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0050] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0051] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0052] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0053] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

Claims

1. A fixation assembly (1) for securing an electrical busbar (2) to at least one of a cooling plate (3) or housing, wherein the fixation assembly comprises:- the electrical busbar (2);- the cooling plate (3) having a recess (5) configured to receive a lower metal insert (6), and optionally a thermal interface material (TIM) layer (7), whereby at least a part of the lower metal insert being arranged in or on the cooling plate;- an upper metal insert (8) extending through an opening (9) in the electrical busbar (2); and- a fastening element (10) configured to engage the upper metal insert with the lower metal insert so as to clamp the electrical busbar against the cooling plate, wherein a clamping force between the busbar and the cooling plate is transmitted through the upper and lower metal inserts.

2. The fixation assembly of claim 1, wherein a plastic layer (11) surrounds at least part of the upper metal insert, the plastic layer providing electrical insulation without contributing to the mechanical fixation, and wherein the TIM layer is positioned beneath the busbar and laterally adjacent to the lower metal insert, allowing thermal conduction, and wherein the fastening element comprises a nut located above the busbar, and wherein the upper metal insert comprises a cylindrical stud or shaft configured to pass through aligned openings in the busbar, the plastic layer, and the TIM layer, and wherein the lower metal insert comprises a cup-shaped or T-shaped metallic element embedded in the cooling plate, and wherein the fixation assembly is configured such that clearance variations or creep in the plastic layer do not alter the clamping force applied to the busbar.