Method for manufacturing a busbar assembly

Abstract

The invention relates to a method for manufacturing a busbar arrangement (2, 2', 2"), comprising at least one busbar (4) with two busbar ends (6, 8), and a hollow cylindrical filter element (10), wherein the filter element (10) is pushed onto the busbar (4) from a substantially straight busbar end (8), wherein the filter element (10) is positioned at a desired location on the busbar (4), and wherein the busbar end or each busbar end (8) is subsequently formed.

Description

[0001] The invention relates to a method for producing a busbar assembly comprising at least one busbar with two ends and a hollow cylindrical filter element. The invention further relates to a correspondingly produced busbar assembly and the use of the busbar assembly in an electric drive.

[0002] Electrically or electric-powered or drivable motor vehicles, such as electric or hybrid vehicles, typically include an electric motor as the electric (traction) drive, which can drive one or both vehicle axles. To supply electrical energy, the electric motor is usually connected to an on-board (high-voltage) battery as an electrical energy storage device.

[0003] To control the speed of the drive, a converter, particularly a frequency converter or inverter, is connected between the battery and the drive. This converter generates a multi-phase output voltage with a variable frequency from the battery's DC voltage. Busbars, i.e., rigid electrical conductors, are often used to carry the voltage or a corresponding current. These busbars are designed, for example, as stamped and bent parts or forged parts. The busbars are bent or angled in such a way that the most effective, compact, and loss-free current conduction is ensured.

[0004] A (DC) intermediate circuit is connected downstream of the battery, to which a bridge circuit of the inverter is connected. Pulse-width modulated (PWM) control of semiconductor switches in a bridge circuit converts the DC voltage into the output voltage. The pulses from the PWM control switch the semiconductor switches between a conducting and a blocking state in a timed manner.

[0005] The switching operations of the semiconductor switches generate alternating currents in the lines of the intermediate circuit or power source. In addition to the fundamental oscillation, electromagnetic interference is generated due to the clock frequency and voltage pulses, which can interfere with the fundamental signal and disrupt the vehicle electrical system. This interference is considered critical for compliance with EMC (electromagnetic compatibility) guidelines. EMC filters are typically used to reduce this interference.

[0006] DE 10 2019 207 499 A1 discloses an inverter for an electric drive train, in which a busbar arrangement is provided for direct current conduction. To improve EMC, the busbar arrangement passes through an EMC filter arrangement.

[0007] EMC filters are typically hollow-cylindrical or tubular chokes or inductors arranged along the busbars. Due to bends or angles in the busbars, it is generally not possible to retrofit a busbar assembly with such an EMC filter. To solve this problem, busbar assemblies with multi-part busbars are used. The EMC filter is pushed onto a straight section of a first busbar, and a second busbar is then joined, in particular screwed, to the first busbar and / or the EMC filter.

[0008] Due to the multi-part design of the busbars, such busbar arrangements with EMC filters often require more space. Furthermore, unlike single-piece busbars, contact resistance occurs at the interface between the busbars. The multi-part design also requires increased material usage and complicates installation in the electric drive due to tolerance chains.

[0009] An electrical circuit device is known from DE 10 2021 130 733 A1. The circuit device comprises a power electronics circuit with at least one power electronics module, a filter device, a heat sink, a terminal, and at least one busbar. The filter device is at least partially coupled to the busbar, and the busbar electrically connects the terminal to the power electronics circuit. The power electronics module and at least a portion of the busbar are thermally connected to the heat sink.

[0010] DE 10 2022 101 327 A1 discloses a ferrite tube core, an interference suppression choke comprising such a ferrite tube core, and a method for forming a ferrite tube core. In one aspect, a ferrite tube core comprises at least two hollow cylindrical core elements, wherein one of the hollow cylindrical core elements is successively arranged at least partially within another of the hollow cylindrical core elements, and the hollow cylindrical core elements are permanently connected to one another.

[0011] DE 10 2017 113 556 B3 describes a filter component which has a first region which is suitable for the passage of at least one busbar, and a second region in which at least one discrete component is arranged, wherein the first region and the second region are separated from one another by a cooling region which thermally decouples the first region from the second region.

[0012] The invention is based on the object of providing a particularly suitable method for producing a busbar assembly. In particular, a manufacturing method is to be provided that enables a reduced and, as space-efficient as possible, compact material use with a preferably simplified process. The invention is further based on the object of providing a particularly suitable busbar assembly and a particularly suitable use of such a busbar assembly.

[0013] With regard to the method, the object is achieved according to the invention by the features of claim 1, with regard to the rail arrangement by the features of claim 5, and with regard to the use by the features of claim 7. Advantageous embodiments and further developments are the subject of the dependent claims.

[0014] The advantages and configurations cited with regard to the method are also transferable to the rail arrangement and / or the use, and vice versa. The conjunction "and / or" is to be understood here and below in such a way that the features linked by this conjunction can be implemented both together and as alternatives to one another.

[0015] The method according to the invention is intended for, and is suitable and designed for, the production of a busbar assembly, in particular for an electric drive, for example, for an electric traction drive of an electrically powered or drivable motor vehicle. The busbar assembly is a preassembled subassembly comprising at least one busbar with two rail ends and a hollow cylindrical or tubular filter element.

[0016] The filter element is designed, in particular, as an EMC filter for the at least one busbar. The filter element is preferably designed as a (filter) choke or (filter) inductor and has a central through-opening (through hole) through which the filter element is placed or plugged onto the busbar. The busbar therefore preferably extends through the filter element.

[0017] The or each busbar is designed as a stamped and bent part or as a forged part. At least one of the busbar ends is essentially straight. A "essentially straight busbar end" is understood here and below to mean, in particular, a busbar end that has no deformation (curvature, bend, kink, offset, angulation, etc.) that is greater than an axial length and / or a radial width (diameter) of the filter element's through-opening. This means that the filter element can be moved collision-free along the straight busbar end when the essentially straight busbar end passes through the filter element.

[0018] According to the method, the filter element is pushed onto the busbar from a substantially straight rail end. This means that the free end of the straight rail end is inserted into the through-opening of the filter element and that the filter element is moved along the straight rail end towards the other rail end. The filter element is positioned at a desired location on or along the busbar, and finally the or each rail end is formed. In particular, a forming operation is effected which is greater than an axial length and / or a radial width (diameter) of the through-opening of the filter element. The formed busbar is also referred to below as a contoured busbar.

[0019] According to the invention, a process sequence during the production of the busbar assembly is thus modified such that the busbar end is only formed after the filter element has been pushed on. This makes it possible to produce a busbar assembly with a one-piece, i.e., monolithic, contoured busbar and with a filter element positioned along the contoured busbar. This realizes a particularly suitable manufacturing method for a busbar assembly.

[0020] The method according to the invention enables a particularly simple and cost-effective process with minimal material usage for the busbar. Furthermore, a particularly compact busbar arrangement is possible. Since the contoured busbar is designed as a single piece, contact resistance between multiple busbar parts is eliminated, thus improving the functionality of the busbar arrangement.

[0021] In an advantageous embodiment, one of the rail ends of at least one busbar is reshaped before the filter element is pushed on, and the other rail end is reshaped after the filter element is pushed on. This reshaped rail end prevents the filter element from accidentally sliding off the busbar during sliding on, for example, thus ensuring particularly simple installation.

[0022] In a suitable refinement, the contoured rail equipped with the filter element is overmolded with a plastic housing, with the rail ends protruding from the housing at the free end. The plastic or the housing is electrically insulating or non-conductive, ensuring reliable and operationally safe current conduction via the busbar arrangement.

[0023] In one possible design, the rail end, which is to be formed after the filter element is pushed on, has a screw tab. This enables simple, reliable, and operationally safe contacting of the busbar assembly.

[0024] An additional or further aspect of the invention provides that a number of busbars, i.e., at least two busbars, preferably at least three busbars, are arranged side by side or stacked one above the other, and that the filter element is pushed onto the busbars together. This results in a particularly space-efficient busbar arrangement.

[0025] The busbar arrangement according to the invention is intended for an electric drive, preferably for an electric traction drive of an electrically powered or drivable motor vehicle, for example, an electric or hybrid vehicle, and is suitable and configured therefor. The busbar arrangement is manufactured according to a method described above. The busbar arrangement has at least one integral, i.e., one-piece or monolithic, contoured busbar, which passes through a filter unit, in particular an EMC filter. This creates a particularly suitable busbar arrangement.

[0026] According to the invention, the busbar arrangement described above is used for an electric drive, preferably for an electric traction drive of an electrically powered or drivable motor vehicle. For example, the busbar arrangement is part of a converter, in particular an inverter. This realizes a particularly suitable use.

[0027] The following examples are explained in more detail using a drawing. They show: Fig. 1 shows a perspective view of a busbar arrangement with three busbars and a filter element, Fig. 2 shows in successive representations a method for producing the busbar arrangement, Fig. 3 in perspective view the busbar arrangement in a second embodiment without the filter element Fig. 4 shows a perspective view of the busbar arrangement in the second embodiment with a housing overmolding, Fig. 5 shows a perspective view of the busbar arrangement in a third embodiment without the filter element, and Fig. 6 shows a perspective view of the busbar arrangement in the third embodiment with a housing overmolding.

[0028] Corresponding parts and sizes are always provided with the same reference symbols in all figures.

[0029] The Fig. Figure 1 shows a schematic and simplified representation of a busbar assembly 2 for an electric drive. The busbar assembly 2 has three busbars 4, each with a first end 6 and a second end 8, which are stacked side by side. A filter element 10 is mounted on the busbars 4 between the ends 6 and 8.

[0030] The filter element 10, which is tubular or hollow-cylindrical, for example, is an EMC filter, which is designed, for example, as a choke or inductor. The filter element 10 has a central through-opening 12 in which the busbars 4 are seated.

[0031] The busbars 4 are designed in particular as one-piece, i.e. single-part or monolithic, contour busbars, wherein the rail ends 6, 8 have such a shape or deformation that the filter element 10 cannot be removed from the busbars 4 without collision.

[0032] The following describes the manufacture of the busbar arrangement 2 using the schematic and simplified representation of the Fig. 2 explained in more detail. The Fig. 2 shows three sections 14, 16, 18 arranged one above the other, in which process steps of the production are shown.

[0033] The three busbars 4 are provided as approximately L-shaped stamped or stamped-bent parts, with the busbar end 6 forming the horizontally angled L-leg, and the busbar end 8 being the free end of the substantially straight vertical L-leg. The busbars 4 are arranged side by side so that the busbar ends 8 run parallel to each other.

[0034] In the method step shown in section 14, the filter element 10 is pushed onto the straight rail ends 8 by means of the through-opening 12. Section 16 shows a positioning of the filter element 10 along the busbars 4 in an assembly position arranged between the rail ends 6, 8. Section 18 shows a forming, in particular a bending, of the rail ends 8. The rail ends 8 are bent or angled by 90°, for example. In the exemplary embodiment shown, the rail ends 8 are bent in particular in the opposite direction to the rail ends 6. The forming of the rail ends 8 is large enough that the filter element 10 cannot be removed over the rail ends 8 without collision.

[0035] According to the method, the filter element 10 is thus pulled onto the busbars 4 from a non-formed rail end 8, and the rail ends 8 are subsequently formed into a deformation.

[0036] The Fig. 3 and Fig. 4 show a second embodiment of the busbar arrangement 2'. The Fig. Figure 3 shows the formed (contoured) busbars 4 without the filter element 10. In this embodiment, the free ends of the busbar ends 8 each have a recess as a screw eyelet 20. In other words, the busbar ends 8 are designed as screw tabs.

[0037] The busbar assembly 2' further comprises a plastic overmold as a housing 22, in which the busbars 4 and at least partially also the filter element 10 are embedded. The busbar ends 6, 8 protrude from the housing 22 as connection contacts.

[0038] In this embodiment, both rail ends 6, 8 are designed to be substantially straight, wherein the busbars 4 are inserted, for example, with the rail ends 6 first into the core or the filter element 10, and the rail ends 8 are subsequently bent over.

[0039] The Fig. 5 and Fig. 6 shows the third embodiment of the busbar arrangement 2". Fig. 5 shows the formed (contour) busbars 4 without the filter element 10. As can be seen particularly in the illustration of Fig. 5, the busbars 4 in this embodiment are designed as forged parts, wherein the seven rail ends 8 are designed, for example, as tubular conductors, each of which ends in a flat connecting lug. List of reference symbols 2, 2', 2" busbar arrangement 4 busbar 6 rail end 8 rail end 10 filter element 12 Through opening 14, 16, 18 Section 20 screw eyelets 22 housings

Claims

[1] Method for producing a busbar arrangement (2, 2', 2"), comprising at least one busbar (4) with two rail ends (6, 8), and a hollow cylindrical filter element (10), - wherein the filter element (10) is pushed onto the busbar (4) from a substantially straight rail end (8), - wherein the filter element (10) is positioned at a desired location on the busbar (4), and - wherein the or each rail end (8) is subsequently reshaped. [2] Method according to claim 1, characterized by that in the at least one busbar (4) one of the rail ends (6) is reshaped before the filter element (10) is pushed on, and the other rail end (8) after the filter element (10) is pushed on. [3] Method according to claim 1 or 2, characterized bythat the formed busbar (4) equipped with the filter element (10) is overmolded with a plastic as a housing (22), wherein the rail ends (6, 8) protrude from the housing (22). [4] Method according to one of claims 1 to 3, characterized by that a number of busbars (4) are arranged next to one another or stacked on top of one another, and that the filter element (10) is pushed onto the busbars (4) together. [5] Busbar arrangement (2, 2', 2") for an electric drive, manufactured by a method according to one of claims 1 to 4. [6] Busbar arrangement (2, 2', 2") according to claim 5, characterized by that the rail end (8) to be reshaped after the filter element (10) has been pushed on has a screw tab. [7] Use of a busbar arrangement (2, 2', 2") according to claim 5 or 6 in an electric drive of a motor vehicle.

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