Method for manufacturing an electric machine and system for manufacturing electric motors

Abstract

A method for manufacturing an electrical machine, characterized in that the method comprises the following steps: - Providing an engine component (10), wherein the engine component (10) has at least one sealing surface (20) for arrangement in an injection molding tool (2) which is designed to keep the engine component (10) partially free of potting compound (30) during overmolding with potting compound (30); - Arranging and sealing the motor component (10) over the at least one sealing surface (20) in a leak test device (1); - Performing a leak test; - Arranging and sealing the motor component (10) in an injection molding tool (2) over the at least one sealing surface (30) and overmolding with potting compound (30).

Description

[0001] The present invention relates to a method for manufacturing an electric machine and a system for manufacturing electric motors.

[0002] To increase stability and improve electrical properties, it is known in the art to overmold electrical components. In particular, rotors of electrically excited synchronous machines are overmolded with a potting compound; see also EP 2 807 728 B1. The main challenge in this context is ensuring that the potting compound only surrounds the intended areas of the component, such as the rotor. If, for example, a rotor is placed in an injection mold for overmolding, dimensional tolerances of the rotor can cause the potting compound, injected under high pressure, to also wet areas of the rotor that should remain untreated, such as the rotor's circumferential surface or the passage for the rotor shaft. If potting compound is present in these areas, this is extremely time-consuming to correct, especially in series production.

[0003] DE 10 2006 001 340 A1 relates to a method for the dense overmolding of a component with plastic, characterized in that an element which has adhesive on at least one surface is used as a connecting element between the component to be overmolded and the plastic, which is positioned towards the component and overmolded with the plastic.

[0004] DE 11 2011 103 922 T5 relates to a metal-resin composite consisting of an aluminum alloy and a molten thermoplastic resin, such as polyphenylene sulfide, and a method for producing the same.

[0005] It is therefore an object of the present invention to provide a method for manufacturing an electric machine and a system for manufacturing electric motors which eliminate the aforementioned disadvantages and enable safe and reliable electric motor manufacturing.

[0006] This problem is solved by a method according to claim 1 and by a system according to claim 7. Further advantages and features will become apparent from the dependent claims, the description, and the accompanying figures.

[0007] According to the invention, a method for manufacturing an electrical machine comprises the following steps: - Providing an engine component, wherein the engine component has at least one sealing surface for arrangement in an injection molding tool, which is designed to keep the engine component partially free of potting compound during overmolding; - Arranging and sealing the engine component via at least one sealing surface on a leak testing device; - Performing a leak test; - Arranging and sealing the motor component in an injection mold over at least one sealing surface and overmolding with potting compound.

[0008] It is therefore advantageous to perform a leak test before overmolding the engine component. Any leaks can be detected and, if necessary, rectified before overmolding. The major advantage lies in the fact that the leak test fixture holds the engine component exactly as the subsequent injection mold will. The leak test fixture seals at the same points as the injection mold. This allows for a very simple and early assurance that no problems will arise during the subsequent overmolding of the engine component, for example, with a potting compound such as a plastic, such as a thermoplastic, preferably a thermoset. These problems could result in areas of the engine component being coated with potting compound that should remain free of it.

[0009] According to a preferred embodiment, the motor component is a rotor of an electric machine, in particular a rotor of a current-excited synchronous machine, such as those used in the automotive sector, for example in passenger cars, but also in commercial vehicles or motorcycles, in the course of hybridization or electrification. According to another embodiment, the motor component can also be a stator of an electric machine or another component intended for overmolding in injection molding.

[0010] According to one embodiment, the method comprises the step: - Reworking of the motor component or rotor before overmolding.

[0011] It has been found that reworking the motor component, especially the rotor, is significantly less complex before overmolding than after. This reworking may consist of reworking at least one sealing surface.

[0012] According to one embodiment, the method comprises the step: - Performing a leak test using a test gas.

[0013] The leak test is advantageously performed in such a way that not only is the tightness verified, but any leaks are also located, allowing for highly targeted rework. Leak testing with test gases has proven extremely efficient, and there are various approaches available, such as testing methods using helium or helium leak detectors. However, leak testing is not limited to the use of test gases; it can also be performed using other methods, such as differential pressure testing or other alternative procedures, which can be selected depending on the requirements.

[0014] According to one embodiment, the method comprises the step: - Conditioning, in particular temperature control, of the leak testing device and / or the engine component.

[0015] Conditioning has the particular advantage that, during the leak test for the engine component, the ambient conditions or boundary conditions are set as closely as possible to those that will later prevail in the injection mold. This can also mean, in particular, that the engine component is advantageously preheated to a specific temperature, since the thermal expansion of the materials of the engine component may result in different sealing forces acting on the sealing surfaces, etc.

[0016] According to one embodiment, the method comprises the step: - Setting a contact force that acts on at least one sealing surface in the leak test device.

[0017] This allows a fundamental idea of ​​the invention to be realized even better, namely that the rotor in the leak test device is arranged in the same way as in the subsequent injection molding tool.

[0018] The invention also relates to a system for manufacturing electric motors, comprising an injection mold and a leak testing device, wherein the injection mold and the leak testing device have identically designed sealing surfaces for arranging and at least partially sealing the motor component, in particular a rotor, especially of a current-excited synchronous machine. The term "identically designed" means, in particular, that the sealing surfaces are dimensioned and positioned identically. In other words, a receptacle for the leak testing device and a receptacle for the injection mold for the rotor are, at least geometrically, identical, which makes it possible to predict that problems will arise during the overmolding of the rotor if the corresponding rotor already shows abnormalities during the leak test.

[0019] The advantages and features mentioned in connection with the procedure also apply analogously and accordingly to the system, and vice versa.

[0020] Further advantages and features will become apparent from the following description of the process or system with reference to the attached figures.

[0021] They show: Fig. 1: a rotor arranged in a leak testing device; Fig. 2: the rotor from Fig. 1, arranged in an injection mold; Fig. 3: the rotor after overmolding with potting compound.

[0022] Fig. Figure 1 shows a schematic representation of a rotor 10 arranged in a leak test device 1. The reference numerals 20 denote sealing surfaces by which the rotor 10 is arranged and sealed in the leak test device. More precisely, both the rotor 10 and the leak test device 1 have sealing surfaces that interact appropriately. The schematic view shows, for example, that the arrangement and design of the sealing surfaces 20 seal a circumferential surface 14 of the rotor and a passage 12 for a rotor shaft (not shown).

[0023] Fig. 2 now shows an arrangement of the material from the Fig. 1 known rotors 10 in an injection mold 2. The schematic representation is intended to make clear that ultimately a receptacle of the injection mold 2 is designed or constructed identically to a receptacle of the leak test device 1, or vice versa.

[0024] Fig. Figure 3 shows a rotor 10 after overmolding with potting compound, wherein, in the view shown here, potting compound 30 is applied only to the end faces, essentially in an annular shape. The circumferential surface 14 or the passage 12 for the rotor shaft, which extends along a rotor axis R, is advantageously free of potting compound. If any leaks or leakage in the leak testing device 1 had been detected during a leak test, see Figure 3. Fig. 1, so before an arrangement of the rotor 10 in the injection mold 2, cf. Fig. 2. Reworking of the rotor can be carried out. Advantageously, this system or method also makes it possible to detect that, for example, the injection mold is worn, if problems occur during overmolding despite a successful leak test. Reference symbol list 1 Leakage testing device 2 injection molds 10 Rotor, motor component 12 passage for rotor shaft 14 Circumferential area 20 sealing surface 30 potting compound R Rotor axis

Claims

[1] Method for manufacturing an electric machine, characterized by , that the procedure includes the following steps: - Providing an engine component (10), wherein the engine component (10) has at least one sealing surface (20) for arrangement in an injection molding tool (2) which is designed to keep the engine component (10) partially free of potting compound (30) during overmolding with potting compound (30); - Arranging and sealing the motor component (10) over the at least one sealing surface (20) in a leak test device (1); - Performing a leak test; - Arranging and sealing the motor component (10) in an injection molding tool (2) over the at least one sealing surface (30) and overmolding with potting compound (30). [2] Method according to claim 1, wherein the motor component (10) is a rotor of an electric machine. [3] Method according to claim 1 or 2, comprising the step: - Reworking of the engine component (10) before overmolding. [4] Method according to any one of the preceding claims, comprising the step: - Performing a leak test using a test gas. [5] A method according to any one of the preceding claims, comprising the step of: - Conditioning the leak test device (1) and / or the engine component (10). [6] Method according to any one of the preceding claims, comprising the step: - Setting a contact force acting on at least one sealing surface (30) in the leak test device (1). [7] System for electric motor manufacturing, comprising an injection mold (2) and a leak testing device (1), characterized by , that the injection molding tool (2) and the leak testing device (1) for arranging and at least partially sealing an engine component (10) have identically designed sealing surfaces (30).

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