Inverter for operating an electric drive of an electric vehicle or a hybrid vehicle and method for assembling such an inverter

Abstract

Inverter (135) for operating an electric drive (115) of an electric vehicle (100) or a hybrid vehicle, comprising at least one busbar (200) with an interface (230) for connecting at least one contact element (215), wherein the busbar (200) has a recess (400) through which a longitudinal section (305) of the contact element (215) is axially passed, the outer diameter of which is smaller than an inner diameter of the recess (400), wherein a metal sheet (310) is arranged in the region of the recess (400) of the busbar (200), which metal sheet is integrally connected to the longitudinal section (305) of the contact element (215) and to the busbar (200).

Description

[0001] The present invention relates to an inverter for operating an electric drive of an electric vehicle or a hybrid vehicle, comprising a busbar and at least one contact element, which is provided, for example, for a plug arrangement.

[0002] The prior art discloses at least partially electrically powered vehicles, such as pure electric vehicles or hybrid vehicles, which can be driven with at least one electric motor as the drive unit. To supply the electric motor of such electric or hybrid vehicles with electrical energy, the vehicles comprise electrical energy storage devices, in particular rechargeable electric batteries. These batteries are designed as direct current sources, but the electric motors generally require alternating current. Therefore, a power electronics unit with a so-called inverter is typically connected between a battery and an electric motor of an electric or hybrid vehicle.

[0003] The contacting of busbars, which are designed, for example, as busbars in electrical drive systems, is usually achieved by directly welding or screwing the busbar to contacts of an external interface, particularly a connector assembly. This is either complex and therefore costly to manufacture, for example, due to the required thread cutting, causes undesirable distortion during assembly, and / or results in relatively large tolerance chains.

[0004] DE 10 2021 209 142 A1 discloses a mounting module for connecting at least one phase output of an inverter device for a vehicle, comprising at least one rail device, wherein the rail device has an input connection for contacting the inverter device and an output connection, a plastic sheath, wherein the plastic sheath partially encloses the at least one rail device, and at least one sensor section for measuring a process variable of the mounting module. The plastic sheath encloses the at least one sensor section at least partially and / or holds it in a materially bonded manner.

[0005] One object of the invention is to provide an inverter in which a connection between the busbar and an interface, in particular for a connector assembly, can be implemented more easily. The invention achieves this object by means of the subject matter of the independent claims. Subclaims specify preferred embodiments.

[0006] According to a first aspect of the invention, an inverter for operating an electric drive of an electric vehicle or a hybrid vehicle comprises at least one busbar with an interface for connecting at least one contact element, wherein the busbar has a recess through which a longitudinal section of the contact element is guided axially, the outer diameter of which is smaller than an inner diameter of the recess, wherein a metal sheet is arranged in the region of the recess of the busbar, which metal sheet is integrally connected to the longitudinal section of the contact element and to the busbar.

[0007] The busbar is typically a metal sheet strip or a busbar made of copper or aluminum, used for electrical power distribution. This transports electrical current and distributes it to consumers. The recess in the busbar can be designed as a hole or a cutout.

[0008] The contact element can be designed in the form of a metallic bolt or a pin and, in principle, can have any cross-sectional shape suitable for connection to an external interface. Thus, the interface of the sheet metal enables the inverter to be connected to an external interface. The contact element is electrically conductive, preferably made of metal. The contact element is connected to the busbar at a free end via a longitudinal section matched to the recess in the busbar. The longitudinal section is formed integrally with the contact element or is part of the contact element and is designed to connect the contact element to the busbar.

[0009] The longitudinal section of the contact element is designed such that it can be axially inserted into the recess with radial play. In other words, the longitudinal section of the contact element can be guided through the recess of the busbar, or is guided through it in the assembled state, due to the difference between the outer diameter of the longitudinal section and the inner diameter of the corresponding recess. This means that the longitudinal section can be guided through the recess of the busbar essentially without contact. "Contact-free" means that due to the difference between the inner diameter of the recess of the busbar and the outer diameter of the longitudinal section, a circumferential gap exists between the longitudinal section and the busbar.

[0010] After the longitudinal section has been passed through the recess, the sheet metal is arranged in the area of ​​the recess in such a way that a material connection can be created both between the sheet metal and the busbar and between the sheet metal and the longitudinal section of the contact pin.

[0011] When assembled and firmly bonded, the sheet acts as an electrical bridge between the busbar and the contact element. Because the sheet is firmly bonded to both the contact element and the busbar, the sheet creates an electrically conductive connection between the contact element and the busbar, regardless of the tolerances between the longitudinal section and the busbar recess. These tolerances are compensated for by the sheet.

[0012] The sheet metal is preferably arranged on a side of the busbar facing away from the contact element. In other words, the sheet metal is arranged on a rear side or opposite side of the busbar with respect to the contact element, so that the busbar is arranged between the sheet metal and the remaining contact element.

[0013] Since the diameter of the contact element allows for a wide tolerance to the diameter of the busbar recess, these two parts can be installed or pre-assembled easily and stress-free. The integral connection between the sheet metal and the contact element on the one hand and the busbar on the other ensures the fixation and contact of the contact element in the inverter. The integral connection between the busbar and the sheet metal and the welding of the sheet metal and the contact element ensures stable and stress-free contact.

[0014] A material-to-material connection here includes, for example, welding, especially with or without filler metal, hard or soft soldering, gluing, or lamination. Since the parts to be joined are preferably metallic components, a material-to-material connection by welding is advantageous. In this sense, the sheet metal is preferably welded to the contact element and the busbar. Accordingly, the sheet metal is considered a welded sheet. The use of welded sheets significantly simplifies the assembly and contacting between the contact element and the busbar.

[0015] According to one embodiment, the sheet metal has a recess corresponding to the cross-section of the longitudinal section of the associated contact element. The sheet metal is essentially annular disk-shaped. The sheet metal can in particular be an annular disk with a tab integrally formed thereon. After the longitudinal section has been passed through the recess in the busbar, the sheet metal is threaded or pushed onto the free end of the longitudinal section on the opposite side of the busbar. The material connection is then made to both the busbar and the longitudinal section. The diameter of the sheet metal, which is particularly easy to manufacture, is matched to the cross-section of the longitudinal section of the contact element. The inner diameter of the recess in the sheet metal can have a narrower tolerance range than the inner diameter of the recess in the busbar.Accordingly, the inner diameter of the recess in the sheet metal is larger than the outer diameter of the longitudinal section of the contact element and smaller than the inner diameter of the recess on the busbar.

[0016] Preferably, the sheet metal is threaded onto the longitudinal section of the contact element in such a way that it rests at least partially on the busbar. This creates a contact between the busbar and the sheet metal, which is secured by the subsequent material-to-material connection.

[0017] In a further development of the invention, the longitudinal section of the contact element extends through the recess of the busbar to such an extent that a front end of the longitudinal section and an outer side of the sheet facing away from the busbar lie in a plane, or that the front end of the longitudinal section protrudes beyond the outer side of the sheet facing away from the busbar. This ensures a secure, integral connection between the contact element and the sheet.

[0018] To simplify manufacturing, the longitudinal section of the contact element preferably has a circular cross-section. Accordingly, the recess in the busbar and the cutout in the sheet metal also have a substantially circular cross-section. The longitudinal section is therefore a cylindrical section at the free end of the contact element. The longitudinal section can be designed in the form of a taper at the free end of the contact element if the remaining contact element must be designed to correspond to external interfaces or connector arrangements. This, however, allows a type of shoulder or axial stop to be realized in order to define a desired axial position of the contact element relative to the busbar during assembly.

[0019] The inverter preferably has a plurality of busbars, each busbar being assigned a contact element. Thus, the inverter has a plurality of contact elements, each of which is connected to the associated busbar. The busbars are brought together at the interface, with the contact elements arranged axially parallel to one another, such that the contact elements can be connected to a common external interface, in particular a connector arrangement.

[0020] Everything said above and below regarding a busbar applies equally to embodiments that have two or more than two busbars.

[0021] A method according to the invention for assembling an inverter according to the first aspect of the invention comprises the method steps: providing an inverter with at least one busbar, having a recess for receiving a longitudinal section of an associated contact element; providing at least one contact element with a longitudinal section whose outer diameter is smaller than an inner diameter of the recess of the busbar; axially passing the longitudinal section of the contact element through the recess of the busbar; arranging a metal sheet between the longitudinal section and the busbar; and materially connecting the metal sheet first to the longitudinal section of the contact element and then to the busbar, or first to the busbar and then to the longitudinal section of the contact element. The busbar and the contact element are preferably connected to the metal sheet by welding.

[0022] Preferably, if the sheet metal has a recess corresponding to the cross section of the longitudinal section, it is threaded onto the longitudinal section after the longitudinal section of the contact element has been passed through the recess and before the material connection, so that the sheet metal rests at least partially on the busbar.

[0023] According to a further aspect of the invention, an electric drive for an electric vehicle or a hybrid vehicle comprises an inverter described herein. The electric drive can in particular comprise or be an electric drive axle, also called an electric axle. By means of an electric machine of the electric drive and a transmission optionally operatively connected thereto, a torque and a rotational speed for driving at least one drive wheel of the motor vehicle are provided. The transmission can be operatively connected to a differential, which can distribute the drive power between two output shafts, each of which is connected to a drive wheel of the same axle. The electric machine, the inverter, and an optional controller are supplied with electrical energy by an energy storage device.

[0024] The invention will now be described in more detail with reference to the accompanying figures, in which: Fig. 1 is a highly schematic plan view of an electric drive according to the invention for an electric vehicle with an inverter according to the invention according to a preferred embodiment; Fig. 2 a schematic perspective view of the inverter according to the invention, only partially shown; Fig. 3 a schematic sectional view of an interface of the inverter for connecting the inverter to an external interface; Fig. 4 a schematic detailed sectional view of the interface to illustrate the connection of a contact element to a busbar of the inverter according to the invention; and Fig. 5 is a block diagram illustrating a method according to the invention for assembling the inverter according to the invention.

[0025] Fig. 1 shows an electric vehicle 100 with two axles 105, 110, wherein the first axle 105 is configured as an electrically driven rear axle and the second axle 110 as a non-driveable, steerable front axle. An electric drive 115 is operatively arranged on the first axle 105. The electric drive 115 comprises an electric machine 120 and a transmission 125, wherein a drive power of the electric machine 120 is converted by the transmission 125 and, depending on the configuration, transmitted to at least one wheel 130 of the first axle 105. A differential—not shown here—can be provided to drive both wheels 130 of the first axle 105. If an internal combustion engine is provided, the vehicle can also be configured as a hybrid vehicle.

[0026] The electric drive 115 further comprises an inverter 135 for operating the electric drive 115, wherein the inverter 135 and the electric machine 120 are connected to an energy storage device (not shown here) for supplying electrical energy.

[0027] The inverter 135 comprises Fig. 2 shows three busbars 200, 205, 210, which are joined at a common interface 230 to connect a respective contact element 215, 220, 225 to a respective busbar 200, 205, 210. The contact elements 215, 220, 225 are provided to electrically connect the inverter 135 to an external connector arrangement (not shown here). In other words, the inverter 135 has a plurality of busbars 200, 205, 210, with each busbar 200, 205, 210 being assigned a contact element 215, 220, 225. The busbars 200, 205, 210 are metallic busbars and the contact elements 215, 220, 225 are metallic, bolt-shaped connector elements that can be connected to an external connector arrangement.

[0028] The interface 230 is in Fig. 3 in conjunction with Fig. 4 is shown in more detail. The connection of the first contact element 215 to the first busbar 200 is described in more detail below. However, the following description is analogously applicable to the connection of the second contact element 220 to the second busbar 205 and the connection of the third contact element 225 to the third busbar 210. Therefore, for the sake of clarity, the description will not be repeated.

[0029] The first Busbar 200 points Fig. 4 in conjunction with Fig. 3 has a circular recess 400 through which a cylindrical longitudinal section 305 of the first contact element 215 is axially guided in the form of a taper of the first contact element 215. The longitudinal section 305 thus has a circular cross-section. The outer diameter 405 of the longitudinal section 305 is smaller than an inner diameter 410 of the recess 400, so that there is initially radial play between the first busbar 200 and the first contact element 215, and the first contact element 215 is mounted on the first busbar 200 without stress.

[0030] Subsequently, an annular disk-shaped sheet 310 with a recess 315 is pushed on from a side of the first busbar 200 opposite the first contact element 215 until the sheet 310 comes to rest on the first busbar 200 or rests against the first busbar 200.

[0031] Out of Fig. 4 shows more clearly that an inner diameter 413 of the recess 315 of the sheet 315 is larger than the outer diameter 405 of the longitudinal section 305 but smaller than the inner diameter 410 of the recess 400 of the first busbar 200. The sheet 310 has a recess 315 corresponding to the cross section of the longitudinal section 305 of the contact element 215. The longitudinal section 205 of the first contact element 215 is further guided through the recess 400 of the first busbar 200 to such an extent that after the sheet 310 has been pushed or threaded onto the longitudinal section 305, a front end of the longitudinal section 305 protrudes slightly beyond the outer side 415 of the sheet 310 facing away from the first busbar 200.

[0032] In the Fig. In the arrangement shown in Figure 4, after threading the sheet 310 onto the longitudinal section 305, the sheet 310 is firmly bonded to both the longitudinal section 305 of the first contact element 215 and the first busbar 200 in the form of a respective welded connection. Thus, the sheet 310 is welded to the first contact element 215 and the first busbar 200.

[0033] Fig.5 illustrates the inventive method 500 described herein for assembling the inverter 135. According to a first method step 505, the inverter 135 is provided with a plurality of busbars 200, 205, 210. In a second method step 510, an associated contact element 215, 220, 225 is provided for each busbar 200, 205, 210. Method steps 505 and 510 can also be performed in reverse order. In a third method step 515, the longitudinal section 305 of the respective contact element 215, 220, 225 is passed axially through the associated recess 400 of the respective busbar 200, 205, 210. In a fourth method step 520, a sheet 310 is arranged between the longitudinal section 305 of the respective contact element 215, 220, 225 and the associated busbar 200, 205, 210.Specifically, the annular disc-shaped sheet 310 is threaded onto the respective longitudinal section 305 as a welding sheet until the sheet 310 rests on a side of the respective busbar 200, 205, 210 facing away from the contact elements 215, 220, 225. In a subsequent process step 525, the respective sheet 310 is welded to the associated busbar 200, 205, 210, so that a materially bonded connection is formed between the respective sheet 310 and the associated busbar 200, 205, 210. In a method step 530, the respective sheet 310 is welded to the longitudinal section 305 of the associated contact element 215, 220, 225, creating a materially bonded connection between the sheet 310 and the associated contact element 215, 220, 225. Method steps 525 and 530 can also be performed in reverse order. Reference symbol 100 electric vehicles 105 First Axis 110 Second Axis 115 electric drive 120 electric machine 125 gearbox 130 wheels 135 inverters 200 first bus bar 205 second bus bar 210 third bus bar 215 first contact element 220 second contact element 225 third contact element 230 interface 305 Longitudinal section of the contact element 310 sheet metal 315 Recess of the sheet 400 Busbar recess 405 Outer diameter of the longitudinal section 410 inner diameter of the recess 413 Inner diameter of the recess of the sheet 415 Outside of the sheet 500 procedures Provide 505 inverters with busbars Provide 510 contact elements 515 Passing the longitudinal section 520 Arrange sheet metal 525 Weld sheet metal with busbar 530 Weld sheet with contact element

Claims

[1] Inverter (135) for operating an electric drive (115) of an electric vehicle (100) or a hybrid vehicle, comprising at least one busbar (200) with an interface (230) for connecting at least one contact element (215), wherein the busbar (200) has a recess (400) through which a longitudinal section (305) of the contact element (215) is axially passed, the outer diameter of which is smaller than an inner diameter of the recess (400), wherein in the region of the recess (400) of the busbar (200) a metal sheet (310) is arranged, which is materially connected to the longitudinal section (305) of the contact element (215) and to the busbar (200). [2] Inverter (135) according to claim 1, wherein the sheet (310) is arranged on a side of the busbar (200) facing away from the contact element (215). [3] Inverter (135) according to claim 2, wherein the sheet (310) has a recess (315) corresponding to the cross section of the longitudinal section (305) of the contact element (215). [4] Inverter (135) according to claim 2 or claim 3, wherein the sheet (310) rests at least partially on the busbar (200). [5] Inverter (135) according to one of claims 2 to 4, wherein the longitudinal section (305) of the contact element (215) is guided through the recess (400) of the busbar (200) to such an extent that a front end of the longitudinal section (305) and an outer side (415) of the sheet (310) facing away from the busbar (200) lie in one plane or that the front end of the longitudinal section (305) protrudes beyond the outer side (415) of the sheet (310) facing away from the busbar (200). [6] Inverter (135) according to one of the preceding claims, wherein the sheet (310) is welded to the contact element (215) and the busbar (200). [7] Inverter (135) according to one of the preceding claims, wherein the longitudinal section (305) of the contact element (215) has a circular cross-section. [8] Inverter (135) according to one of the preceding claims, wherein the inverter (135) has a plurality of busbars (200, 205, 210), each busbar (200, 205, 210) being assigned a contact element (215, 220, 225). [9] Method (500) for assembling an inverter (135) according to one of the preceding claims, comprising the method steps: providing an inverter (135) with at least one busbar (200) having a recess (400); providing at least one contact element (215) with a longitudinal section (305) whose outer diameter is smaller than an inner diameter of the recess (400) of the busbar (200); axially passing the longitudinal section (305) of the contact element (215) through the recess (400); arranging a metal sheet (310) between the longitudinal section (305) and the busbar (200); and materially connecting the sheet (310) first to the longitudinal section (305) of the contact element (215) and then to the busbar (200) or first to the busbar (200) and then to the longitudinal section (305) of the contact element (215). [10] Method (500) according to claim 9, wherein the sheet metal (310) has a recess (400) corresponding to the cross section of the longitudinal section (305), wherein after the longitudinal section (305) of the contact element (215) has been passed through the recess (400) and before the material connection, the sheet metal (310) is threaded onto the longitudinal section (305) so that the sheet metal (310) rests at least partially on the busbar (200). [11] Electric drive (115) for an electric vehicle or a hybrid vehicle, comprising an inverter (135) according to one of claims 1 to 8.

Images