Method for potting a drive unit

Abstract

The invention relates to a method for potting a drive unit (12), at least having a dynamo-electric machine (11) with an end shield (10) and a converter (14) which has at least one power electronics element (13), wherein the converter (14) is integrated or at least partially integrated into the end shield (10), the method comprising the following steps: mounting the end shield (10) in the axial direction; rotating the end shield (10); applying a potting material (2) to the end shield (10); and curing the potting material (2), wherein the end shield is rotated during curing until the potting material gels.

Description

[0001] Description

[0002] Method for potting a drive unit

[0003] The invention relates to a method for potting a drive unit.

[0004] Drives in which the inverter is integrated into the motor's interior are advantageous. In this case, the inverter is, for example, mounted axially behind the stator winding in the housing or integrated into the end shield. A combined solution, encompassing both the housing and end shield, is also conceivable.

[0005] By (partially) integrating the inverter into the end shield, the inverter's power electronics components are preferably mounted directly into or onto the end shield inside the motor. Here, the securing and dissipation of the heat generated by the power electronics during operation is particularly important for the overall drive performance.

[0006] The power components can, for example, be mechanically fixed radially to an inner side of the bearing shield. However, there is a risk that the fixed elements will loosen again due to vibrations, for example. Protection against environmental influences, such as moisture from condensation, is also lacking. Furthermore, heat dissipation through thermal paste, for example, between the power component and the mounting geometry of the bearing shield is disadvantageous.

[0007] The invention is based on the objective of improving this.

[0008] The problem is solved by claim 1, i.e., a method for potting a drive unit, comprising at least a dynamoelectric machine with a bearing shield and an inverter comprising at least one power electronic element, wherein the inverter is integrated or at least partially integrated into the bearing shield, comprising the following steps:

[0009] - Clamping the bearing shield in the axial direction,

[0010] - Rotating the bearing shield,

[0011] - Applying a potting compound to the bearing plate,

[0012] - Curing of the potting compound, whereby the bearing shield is rotated during curing until the potting compound gels. Drives in which the inverter is integrated into the motor housing are advantageous, and the described method is particularly suitable. The inverter is, for example, mounted axially behind the stator with winding in the housing or integrated into the bearing shield.

[0013] One advantage over a separate setup is, for example, that there are no external cables between the inverter and the motor, resulting in simpler commissioning and lower winding stress.

[0014] One advantage over top-mounted converters is the retention of the clearance profile, therefore easier retrofitting is possible.

[0015] Furthermore, a targeted coordination of the two components and optimized operating behavior are advantageous.

[0016] The power electronic element is advantageously mechanically fixed in and / or on an inner side of the bearing shield.

[0017] The bearing shield is rotated, particularly during curing, until the potting material gels. This allows the at least one power electronic element in the bearing shield to be completely encapsulated, essentially without voids, and without the need for molding tools or casting barriers remaining in the product. The rotation advantageously distributes the potting material evenly.

[0018] An advantageous embodiment uses an epoxy-based potting compound. Epoxy potting compounds are available in various formulations, such as two-component or process-optimized versions. Furthermore, they offer good thermal stability.

[0019] An advantageous embodiment is one in which the potting material has a thermal conductivity in the range of at least 1 W / mK and at most 8 W / mK.

[0020] This ensures particularly good heat dissipation.

[0021] An advantageous embodiment is one in which the distribution of the potting material is influenced by adjusting the potting material properties with regard to thixotropy and / or viscosity.

[0022] The distribution of the potting compound can be additionally or alternatively influenced by pre-heating the bearing shield. The distribution of the potting compound can also be influenced by changing the rotational speed and / or direction of rotation.

[0023] An advantageous rotational speed is at least five revolutions per minute and at most 50 revolutions per minute.

[0024] The distribution of the potting material can be additionally or alternatively influenced by changing the volume flow rate of the potting material.

[0025] In this way, the material can be easily poured and distributed into the areas to be filled.

[0026] An advantageous embodiment is one in which the potting material is cured at ambient temperature and / or cured by the application of heat.

[0027] Thermal curing is successful at temperatures of at least 100°C, and particularly successful at temperatures of at least 120°C.

[0028] Between 150°C and 180°C, depending on the material properties or the manufacturer's recommendations in the data sheets, is an advantageous maximum temperature for curing.

[0029] Similarly, the duration can range from several hours down to just a few minutes (in the case of 2K variants).

[0030] Curing at ambient temperature, particularly at least 15°C and at most 25°C, is also possible. For this, a longer curing period is advantageous, for example, at least 20 hours and at most 25 hours. Approximately one day can be allowed for curing.

[0031] An advantageous embodiment involves rotating the bearing shield during curing until the potting material gels. This is advantageous for both curing at ambient temperature and curing with active heat input.

[0032] This way, voids can be avoided. An advantageous embodiment uses a potting resin as the casting material.

[0033] The use of epoxy resin is advantageous. Epoxy resin is hard and tough and exhibits only minimal shrinkage during curing. Furthermore, the mechanical properties of epoxy resin are beneficial. Epoxy resin also offers good resistance to high temperatures.

[0034] Other potting resins are also possible.

[0035] An advantageous embodiment is one in which the potting material is a one-component resin system or a two-component resin system.

[0036] Both variants are available in numerous modifications. A one-component (1K) material is easy to process but requires more energy and time to cure. A two-component (2K) material, on the other hand, is more complex to process, as the mixing must occur immediately during dispensing.

[0037] An advantageous embodiment is one in which the potting material is applied to the bearing shield using at least one metering nozzle.

[0038] This ensures that the correct areas can be reliably filled.

[0039] The problem can also be solved by a drive unit comprising at least a dynamoelectric machine with a bearing shield and an inverter comprising at least one power electronic element, wherein the inverter is integrated or at least partially integrated into the bearing shield, potted according to such a method.

[0040] The problem can also be solved by using a potting material for at least partially potting a bearing shield, wherein the bearing shield has at least one power electronic element, wherein the potting material is applied to the bearing shield and cured by rotating the bearing shield until the potting material gels.

[0041] The invention will now be described and explained in more detail with reference to the exemplary embodiments shown in the figures.

[0042] Figure 1 shows a bearing plate.

[0043] FIG 2 a drive unit,

[0044] FIG 3 Process steps.

[0045] FIG 1 shows a bearing shield 10 of a dynamo-electric rotary machine.

[0046] The bearing shield is advantageously rotated about an axis of rotation A. Either a rotation direction R1 or a rotation direction R2 can be selected. It is also possible to rotate alternately, for example, first in one rotation direction R1 and then in the other rotation direction R2. In FIG. 1, potting material 2 is introduced through a nozzle 3.

[0047] The inverter 14 is, see also FIG 2, integrated or partially integrated into the bearing shield 10.

[0048] The invention makes it possible to achieve a complete encapsulation without the need for molding tools or elements incorporated into the product, such as a ring as a pouring stop or a plastic cap. The encapsulation is achieved without these elements and without any potting tools.

[0049] The elements of the power electronics parts are arranged on the inside of the bearing shield 10 and are advantageously mechanically fixed, see fixing 20.

[0050] To achieve permanent fixation, heat dissipation, and protection against environmental influences, the areas are encased in a potting compound, preferably thermally conductive. Resins, such as epoxy-based, one-component (1K) or two-component (2K) resin systems (K stands for components), are advantageous here. However, potting compounds made of other materials can also be used.

[0051] The thermal conductivity of the potting material 2 used is advantageously in the range of 1 W / mK to 8 W / mK.

[0052] For potting, the equipped bearing shield 10 is axially clamped and set in rotation.

[0053] The potting compound 2 is advantageously applied to the rotating inner area of ​​the bearing shield 10 containing the power electronics via metering units (so-called nozzles 3). The material comes into contact with the power electronics and the interior of the bearing shield and is distributed evenly in the areas to be potted by the rotation. The distribution of the potting compound 2 can be controlled by adjusting the material properties (especially with regard to thixotropy and / or viscosity), pre-heating of the component (especially the bearing shield), rotational speed, direction of rotation, and / or volumetric flow rate of the potting compound 2.

[0054] The curing process then takes place, preferably at temperatures above 120 °C for several hours. For two-component resin systems in particular, curing at ambient temperature is suitable. The curing process takes approximately 24 hours.

[0055] Curing is advantageously carried out in a rotating motion until the potting material 2, in particular the resin, has gelled. Even with materials that cure at ambient temperature, the rotation can be stopped once the gelling point is reached.

[0056] The use of potting tools is not required.

[0057] Rotational potting allows for a void-free finish, as air can escape. This has a positive effect on the thermal conductivity and the mechanical fixation of the entire system.

[0058] The advantages of the described rotary potting process are, in particular: The elimination of all potting tools or components required for the potting process. This results in cost reduction. It enables void-free potting. The potting process can be automated. Design changes have little or no impact on the potting or the process. Furthermore, quality assurance is possible through complete process monitoring.

[0059] FIG 2 shows a drive unit 12 comprising a dynamoelectric rotary machine 11 with a bearing shield 10 and a shaft 15.

[0060] A converter 14 with at least one power electronic element is at least partially integrated into the bearing shield 10.

[0061] FIG 3 shows process steps.

[0062] In process step S1, the bearing shield is clamped in the axial direction.

[0063] In process step S2, the bearing shield is rotated. In process step S3, a potting material is applied to the bearing shield.

[0064] In process step S4, the potting material is hardened.

Claims

8 Patent claims 1. Method for encapsulating a drive unit (12), comprising at least a dynamoelectric machine (11) with a bearing shield (10) and an inverter (14) comprising at least one power electronic element (13), wherein the inverter (14) is integrated or at least partially integrated into the bearing shield (10), comprising the following steps: - Clamping the bearing shield (10) in the axial direction, - Rotating the bearing shield (10), - Applying a potting compound (2) to the bearing shield (10), - Curing of the potting material (2), wherein the bearing shield is rotated during curing until the potting material gels.

2. Method according to claim 1, wherein the potting material (2) is epoxy-based.

3. Method according to one of the preceding claims, wherein the potting material (2) has a thermal conductivity in the range of at least 1 W / mK and at most 8 W / mK.

4. Method according to one of the preceding claims, wherein a distribution of the potting material (2) is influenced by adjusting the potting material properties with respect to thixotropy and / or viscosity.

5. Method according to one of the preceding claims, wherein a distribution of the potting material (2) is influenced by pre-tempering the bearing shield (10).

6. Method according to one of the preceding claims, wherein a distribution of the potting material (2) is influenced by changing a rotational speed and / or direction of rotation (R1 , R2).

7. Method according to one of the preceding claims, wherein a distribution of the potting material (2) is influenced by a change in a volume flow of the potting material (2).

8. Method according to any of the preceding claims, wherein the potting material (2) is cured at ambient temperature and / or cured by the application of heat. 9 9. Method according to one of the preceding claims, wherein the bearing shield (10) is rotated during curing until the casting material (2) gels.

10. Method according to any of the preceding claims, wherein the potting material (2) is a potting resin.

11. Method according to any of the preceding claims, wherein the potting material (2) is a one-component resin system or a two-component resin system.

12. Method according to one of the preceding claims, wherein the potting material (2) is applied to the bearing shield (10) using at least one nozzle (3).

13. Method according to one of the preceding claims, wherein the power electronic element (13) is mechanically fixed in and / or on an inside of the bearing shield (10).

14. Drive unit (12), comprising at least a dynamoelectric machine (11) with a bearing shield (10) and an inverter (14) comprising at least one power electronic element (13), wherein the inverter (14) is integrated or at least partially integrated into the bearing shield (10), encapsulated according to a method according to one of claims 1 to 13.

15. Use of a potting material (2) for at least partial potting of a bearing shield (10), wherein the bearing shield (10) has at least one power electronic element (13), wherein the potting material (2) is applied to the bearing shield (10) and is cured by rotating the bearing shield (10) until the potting material (2) gels.

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