Interface device for electrical connection between an electric motor and an inverter, for example in an e-axis, method for producing the interface device and e-axis

Abstract

The invention relates to an interface device (10) for the electrical connection between an electric motor and an inverter, for example in an electric axle for a vehicle, with three busbars (20) which are permanently connected to one another by an injection-molding compound (22), wherein each of the three busbars (20) comprises a first punched and bent part (21a) made of an electrically conductive material and a second punched and bent part (21b) made of an electrically conductive material, wherein the first punched and bent part (21a) is electrically conductively connected to the second punched and bent part (21b).

Description

State of the art

[0001] From the subsequently published DE 10 2023 210 554 A1 of the applicant, an interface device for an electric axle of a vehicle with busbars that are partially surrounded by a molding compound is already known. Disclosure of the invention

[0002] The present invention is based on the inventors' desire to create an interface device that can be manufactured with little effort.

[0003] For this purpose, in an interface device which has three busbars which are permanently connected to one another by an injection-molding compound, it is provided that each of the three busbars comprises a first punched-bent part made of an electrically conductive material and a second punched-bent part made of the electrically conductive material, wherein the first punched-bent part is electrically conductively connected to the second punched-bent part.

[0004] The reason behind this is the fact that stamped and bent parts can generally be manufactured economically in mass processes.

[0005] However, the inventors further recognized that this advantage is at least partially lost if the parts to be produced using the punching and bending process have a comparatively complex shape. The punched part itself may already have a complex, for example irregular, shape. This means that a semi-finished product, such as a metal or copper strip from which the punched part is produced by punching, can only be used to a small extent. The unused portion, i.e., the waste, is relatively high, which counteracts the cost-effectiveness of the process. In addition, the more complex the punched part, the greater the wear and tear on punching tools.

[0006] On the other hand, a stamped and bent part may have a large number of bends, making it difficult to handle. The same applies to stamped and bent parts that are relatively large or whose bends are relatively close together.

[0007] Based on this, the inventors found a solution that consists in each busbar initially comprising two punched and bent parts. Each of the two punched and bent parts is significantly less complex than the resulting busbar and can therefore be provided simply. This simplification goes so far that it can outweigh the additional effort resulting from the subsequent joining of the two punched and bent parts.

[0008] The connection of the two stamped and bent parts can be achieved particularly economically and robustly by mechanical joining, for example, by pressing the stamped and bent parts into each other. The resulting pressing force between the two connected stamped and bent parts can be further increased by stamping the inserted part after the pressing, especially if measures are taken to prevent lateral deflection of the receiving part during stamping.

[0009] The connection of the two stamped and bent parts can be achieved particularly economically and robustly if the first stamped and bent part is connected to the second stamped and bent part by engaging with the second stamped and bent part or by the second stamped and bent part engaging with it. In other words, one of the stamped and bent parts is male-shaped and one of the stamped and bent parts is female-shaped, and the two stamped and bent parts are connected to each other by means of these formations.

[0010] For this purpose, it can be provided that the engagement of the first punched-bent part with the second punched-bent part creates a positive connection in at least one plane. The strength of the connection is then increased.

[0011] This can be achieved by the first punched-bent part and the second punched-bent part each having a longitudinal extension with an end region, and by the end region of the second punched-bent part having an undercut recess, and the end region of the first punched-bent part being shaped complementarily to the end region of the second punched-bent part, so that it engages in the undercut recess; alternatively, the roles of the first and second punched-bent parts can be interchanged. The undercut recess and the complementary part engaging in it thereby realize the form-fitting connection formed in one plane between the two punched-bent parts.

[0012] Designs with undercut recesses at the complementary end areas of both stamped and bent parts are also possible. This means that both stamped and bent parts are shaped as both male and female at the same time. The strength of the connection is then further increased.

[0013] The complementarily shaped end region can have an engagement section. The engagement section is designed to be complementary to the recess and engage into the recess. For example, it can have the shape of a dovetail, a round shape, or an elliptical shape. It can also have a shape comprising a head section and a neck section. In this illustration, the neck section of the engagement section connects the head section of the engagement section to the stamped and bent part, which is otherwise intended as the body section.

[0014] The busbars can be made of metal or copper or a copper alloy, i.e. materials that have a high conductivity for electrical current.

[0015] The area of ​​a busbar where the first stamped and bent part is connected to the second stamped and bent part can be overmolded with the injection molding compound. This protects the connection between the stamped and bent parts from environmental influences, thus increasing their robustness.

[0016] From a manufacturing perspective, it simplifies the process if the three first stamped and bent parts of the busbar are designed as identical parts. On the other hand, at least two of the three second stamped and bent parts of the busbar can differ from each other in terms of their shape. This allows the interface device to be used between components arranged in almost any way.

[0017] For this purpose, it may be provided or required that each of the three first punched-bent parts and / or each of the three second punched-bent parts has at least two bends, for example bends at an angle of 90° each.

[0018] The invention also relates to an electric axle having a housing in which an inverter, an electric machine and a transmission are integrated, wherein a three-phase output of the inverter is connected to the three-phase input of the electric machine by such an interface device.

[0019] The invention also relates to a method for producing such an interface device with the following method steps: Providing a metal strip, in particular a copper strip, then punching first punched parts and second punched parts from the metal strip, then bending the first punched parts to form first punched-bent parts and bending the second punched-bent parts to form second punched-bent parts, connecting the first punched-bent parts to the second punched-bent parts to form busbars, then overmolding the busbars with the injection molding compound so that the interface device is produced.

[0020] Connecting the first punched and bent parts to the second punched and bent parts to form busbars may involve pressing in. Subsequent stamping of the pressed-in part may be provided. For this purpose, means may be used to prevent the receiving part from lateral displacement during stamping. Short description of the drawings

[0021] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1 an interface device, Fig. 2 the busbars of the interface device from Figure 1 , Fig. 3 a busbar or two punched and bent parts that can be connected to one another to form a busbar according to a first embodiment of the invention, Figure 4 a busbar or two punched and bent parts that can be connected to one another to form a busbar according to a second embodiment of the invention, Figure 5 a busbar or two punched and bent parts that can be connected to one another to form a busbar according to a third embodiment of the invention, Figure 6 the area of ​​a connection between two punched and bent parts in a busbar according to the first embodiment of the invention. Embodiments of the invention

[0022] Figure 1shows an interface device 10, such as can be arranged, for example, within an electric axle (not shown in the drawing) for a vehicle between a three-phase output of an inverter and a three-phase input of an electric machine of the electric axle.

[0023] For this purpose, the interface device 10 has three spaced-apart busbars 20 which are permanently connected to one another by an injection-molding compound 22 of the interface device 10 and are aligned relative to one another.

[0024] The busbars 20 of the interface device 10 are shown in the Figure 2again without the injection molding compound 22, but in their position relative to each other as shown in the interface device 10. It can be seen that the busbars are complexly shaped parts, which, for example, as stamped and bent parts 21a, 21b, have a plurality of bends 25, which, moreover, are comparatively close to each other relative to the material thickness of the busbars 20.

[0025] Figure 3 shows two punched and bent parts 21a, 21b that can be connected to one another to form a busbar 20 according to a first embodiment of the invention. The two punched and bent parts 21a, 21b are made of copper, for example, and each have a longitudinal extension with mutually facing end regions 31a, 31b.

[0026] In the example, it is provided that a first punched-bent part 21a, which is in the Figure 3 shown on the left, into a second punched and bent part 21b, which is in the Figure 3shown on the right, and that thus in a Figure 3 vertical and from the front left to the back right plane forms a positive connection.

[0027] For this purpose, the end region 31b of the second punched-bent part 21b has a recess 35 with the shape of a dovetail and the end region 31a of the first punched-bent part 21a has an engagement section 53 complementary to the recess 35, which consequently also has the shape of a dovetail.

[0028] Figure 6 shows the busbar 20 in the area of ​​the end sections 31a, 31b, after the two stamped and bent parts 21a, 21b have been joined together, for example, using a mechanical joining process. It was verified that the electrical contact resistance in this area is tolerably low.

[0029] Figure 4shows an alternative embodiment in which the recess 35 and the engagement portion 53 comprise a tapered neck portion 35a, 53a and a round, laterally projecting head portion 35b, 53b. In this figure, the first stamped and bent part 21a or its end portion 31a can be considered a body portion.

[0030] Figure 5 shows yet another alternative embodiment in which the recess 35 and the engaging portion 53 are rectangular and have different dimensions.

Claims

1. Interface device (10) for the electrical connection between an electric motor and an inverter, for example in an electric axle for a vehicle, with three busbars (20) which are permanently connected to one another by an injection-molding compound (22), wherein each of the three busbars (20) comprises a first punched and bent part (21a) made of an electrically conductive material and a second punched and bent part (21b) made of an electrically conductive material, wherein the first punched and bent part (21a) is electrically conductively connected to the second punched and bent part (21b).

2. Interface device (10) according to claim 1, wherein the first punched-bent part (21a) is connected to the second punched-bent part (21b) by mechanical joining, for example press-fitting.

3. Interface device (10) according to claim 1 or 2, wherein the first punch-bend part (21a) is connected to the second punch-bend part (21b) by engaging the second punch-bend part (21b) or by the second punch-bend part (21b) engaging it.

4. Interface device (10) according to claim 3, wherein a positive connection is formed by the engagement of the first punched-bent part (21a) in the second punched-bent part (21b) in at least one plane.

5. Interface device (10) according to claim 3 or 4, wherein the first punched-bent part (21a) has a longitudinal extension and wherein the second punched-bent part (21b) has a longitudinal extension and wherein the first punched-bent part (21a) has an end region (31a) in the direction of its longitudinal extension and wherein the second punched-bent part (21b) has an end region (31b) in the direction of its longitudinal extension;and wherein the end region (31ab) of the second punched and bent part (21b) has an undercut recess (35) and the end region (31a) of the first punched and bent part (21a) is shaped complementarily to the end region (31b) of the second punched and bent part (21b) so that it engages in the undercut recess (35), and / or wherein the end region (31a) of the first punched and bent part (21a) has an undercut recess (35) and the end region (31b) of the second punched and bent part (21b) is shaped complementarily to the end region (31a) of the first punched and bent part (21a) so that it engages in the undercut recess (35).; 6. Interface device (10) according to claim 5, wherein the complementarily shaped end region (31a, 31b) has an engagement portion (53) which is shaped complementarily to the recess (35) and which engages in the recess (35).

7. The interface device (10) according to claim 6, wherein the engaging portion (53) has the shape of a dovetail or a round shape or an elliptical shape or a neck-head shape (53a, 53b).

8. Interface device (10) according to one of the preceding claims, wherein the busbars (20) comprise copper or consist of copper.

9. Interface device (10) according to one of the preceding claims, wherein the regions in which the first punched-bent parts (21a) are connected to the second punched-bent parts (21b) are overmolded with the injection molding compound (22).

10. Interface device according to one of the preceding claims, wherein the three first punched and bent parts (21a) of the busbar (22) are designed as identical parts.

11. Interface device (10) according to claim 10, wherein at least two, in particular three, of the three second punched-bent parts (21b) of the busbar (20) differ from one another in pairs with regard to their shape.

12. Interface device (10) according to one of the preceding claims, wherein each of the three first punching and bending parts (21a) and / or each of the three second punching and bending parts (21b) has at least two bends (25), for example bends (25) at an angle of 90° each.

13. A method for producing an interface device (10) according to one of the preceding claims, comprising the following method steps: - providing a metal strip, in particular a copper strip, then - punching first punched parts and second punched parts from the metal strip, then - bending the first punched parts to form first punched-bent parts (21a) and bending the second punched parts to form second punched-bent parts (21b), - connecting the first punched-bent parts (21a) to the second punched-bent parts (21b) to form busbars (20), then - overmolding the busbars (20) with the injection-molding compound (22) so that the interface device (10) is produced.

14. E-axle with a housing in which an inverter, an electric machine and a transmission are integrated, wherein a three-phase output of the inverter is electrically connected to the three-phase input of the electric machine by an interface device (10) according to one of claims 1 to 12.

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