Device with a housing body for an electric machine, wherein the device has a heat sink

Abstract

Device (10) with a housing body (20) for an electric machine (5), wherein the device (10) has a heat sink (30) which is arranged inside the housing body (20), and wherein the housing body (20) has a cross-section with eight corners (21) and the heat sink (30) has a cross-section with eight corners (32) as its basic shape, characterized by the fact that four corners (22) of the octagonal housing body (20) and four corners (32) of the octagonal heat sink (20) are each designed as a circular segment rounded and arranged in such a way that the housing body (20) is shrunk onto the heat sink (30) at these rounded corners (22, 32) for thermal contact between the heat sink (30) and the housing body (20).

Description

State of the art

[0001] The invention relates to a device with a housing for an electric machine, wherein the device includes a heat sink which is arranged inside the housing. Furthermore, the housing has an eight-sided cross-section and the heat sink also has an eight-sided cross-section as its basic shape.

[0002] Such a device is disclosed, for example, in European Patent EP 2 700 146 B1. This patent discloses an electric motor which has an octagonal stator that is press-fitted into an octagonal housing.

[0003] From publication DE 103 53 330 A1, a ventilation housing for an electric machine is known which has a cross-shaped cross-section perpendicular to its longitudinal axis. This cross-shaped form leaves the corner areas of a mounting flange of the electric machine unobstructed, thus ensuring that the mounting screws remain accessible.

[0004] German patent application DE 10 2015 100 981 A1 discloses a cooling device for an electric motor with a cover that surrounds the motor. The electric motor has an octagonal cross-section. The cover makes contact with the electric motor via several adjacent parts, which are arranged such that a gap is formed between the cover and the electric motor to guide cooling air. The contact primarily serves as a spacer to define the air gap.

[0005] German patent application DE 11 2013 006 952 T5 discloses an inverter device housed in a metal casing with an octagonal inner wall. Power semiconductor elements are arranged along this octagonal inner wall to dissipate generated heat to the casing. Disclosure of the invention

[0006] The invention relates to a device with a housing for an electric machine, wherein the device includes a heat sink which is arranged inside the housing. Furthermore, the housing has an octagonal cross-section as its basic shape, and the heat sink also has an octagonal cross-section as its basic shape. A heat sink is understood to be an element that can dissipate heat generated, for example, by a control unit. For this purpose, the heat sink typically exhibits good thermal conductivity.

[0007] The heat is typically dissipated from the heat sink via a housing or directly into the environment. This heat is typically generated by the electronic components located on the control unit's circuit board, which then transfer their heat to the heat sink. To dissipate heat directly into the environment, the heat sink may, for example, have additional cooling fins on the side facing away from the control unit.

[0008] An electronic component is, for example, a capacitor, a semiconductor switch, an inductor, a sensor, or an energy storage device, which, in combination with other electronic components, forms a corresponding electronic circuit for controlling and operating the electric machine. The electronic components are arranged on a circuit board of the control unit and interconnected accordingly.

[0009] The housing body is a component that, among other things, accommodates or encloses the heat sink. Furthermore, the housing body can accommodate or enclose other components of the electric machine, such as the control unit, the stator, and / or the rotor.

[0010] This protects the components housed within the casing from unwanted external influences. Such influences can include, for example, moisture, dirt, and / or mechanical stress.

[0011] One aspect of the invention consists in the fact that four corners of the octagonal housing body and four corners of the octagonal heat sink are each designed as a circular segment and arranged in such a way that the housing body is shrunk onto the heat sink at these rounded corners for thermal contact between the heat sink and the housing body.

[0012] The advantage here is that the surface area of ​​the heat sink, to which the surface area of ​​the circuit board of the electric machine's control unit is typically adapted, is larger compared to a completely cylindrical heat sink. This allows more components to be arranged on the circuit board and also improves heat dissipation. A further advantage is that the shrink-fit process enables a force-free assembly, thus protecting the components.

[0013] A cross-section with eight corners as its basic shape means that the original cross-section is an octagon. However, this octagon has at least some slightly modified corners, which here, for example, are designed as circular segments. The cross-sections of the heat sink and the housing body are shown from a top view. Furthermore, all corners may be slightly rounded. Nevertheless, the octagonal shape of the cross-section remains recognizable in the top view. Only the circularly shaped corners will subsequently be referred to as rounded.

[0014] In one embodiment of the device according to the invention, the rounded corners of the heat sink extend into a plane parallel to a principal plane of extension of the heat sink. It is advantageous that the rounded corners of the heat sink can be produced by a turning process. Such a process is easy to use and allows for cost-effective machining of the heat sink. If, on the other hand, the rounded corners were only in the principal plane of extension of the heat sink, a turning process would not be possible, as this would destroy the other, non-circular segment-shaped corners of the heat sink.

[0015] According to one embodiment of the device according to the invention, it is provided that the rounded corners of the heat sink are arranged on a common first circular path and / or the rounded corners of the housing body are arranged on a common second circular path.

[0016] The advantage here is that it allows for simple shrink-fitting, which nevertheless results in a stable shrink fit. Furthermore, the shared circular path during shrink-fitting ensures the heat sink is centered within the housing. Additionally, manufacturing a body whose corners lie on a common circular path is simple and cost-effective, for example, using a turning process.

[0017] According to one embodiment of the device according to the invention, the housing body is only shrunk onto the heat sink at the rounded corners, and the remaining areas of the housing body are not in contact with the heat sink.

[0018] An advantage of this design is that manufacturing tolerances can be compensated for. This is because the heat sink, due to the device's design, can rotate around an axis perpendicular to its main plane of extension during the shrink-fitting process. The possible rotation is only a few degrees, but this is sufficient to compensate for manufacturing tolerances of the heat sink and / or the housing.

[0019] The remaining areas are those parts of the housing body that are not formed as circular segment-shaped corners.

[0020] According to one embodiment of the device according to the invention, it is provided that the corners of the housing body and / or the corners of the heat sink are designed in cross-section alternately as circular segments and non-circular segments.

[0021] The advantage here is that this arrangement of the rounded corners ensures that the heat sink is centered within the housing body during the shrinking process.

[0022] The invention also relates to an electric machine, in particular an electric motor, with a device according to the invention.

[0023] In this context, an electric motor can refer to, for example, a three-phase machine such as a synchronous machine or an asynchronous machine.

[0024] A manufacturing process for a device according to the invention proceeds, for example, as follows. First, a heat sink and a housing body are provided, each having a cross-section with eight corners as its basic shape. The diameter of the housing body from one rounded corner to the directly opposite rounded corner is smaller than the diameter of the heat sink from one rounded corner to the directly opposite rounded corner. The housing body is then heated and / or the heat sink is cooled so that the heat sink can be inserted into the housing body. After the heat sink has been inserted into the housing body, the housing body is cooled again and / or the heat sink is reheated to create a shrink fit between the heat sink and the housing body. Drawings Fig. Figure 1 shows a top view through a schematically represented electrical machine according to the invention with a device according to the invention. Fig. 2 shows a section through the device according to the invention. Fig. 1. Fig. Figure 3 shows the heat sink of the device according to the invention. Fig. 1 and Fig. 2 in a perspective view. Description of exemplary implementations

[0025] Fig. Figure 1 shows a top view through a schematically represented electrical machine according to the invention with a device according to the invention.

[0026] An electric machine 5 is shown. This electric machine 5 can, for example, be designed as an electric motor and in particular as a synchronous machine or as an asynchronous machine and thus form a three-phase machine.

[0027] The electric machine 5 comprises a device 10 according to the invention. The device 10 in turn comprises a housing body 20 and a heat sink 30. The housing body 20 has a cross-section with eight corners 21 as its basic shape, and the heat sink 30 has a cross-section with eight corners 31 as its basic shape. Here, four corners 22 of the octagonal housing body 20 and four corners 32 of the octagonal heat sink 20 are each designed as a rounded circular segment. The corners 21 of the housing body 20 and the corners 31 of the heat sink 30 are designed in cross-section alternately as circular segments and non-circular segments around their circumference.The four rounded corners 22 of the housing body 20 and the four rounded corners 32 of the heat sink 20 are designed such that the housing body 20 is shrunk onto the heat sink 30 at these rounded corners 22, 32 for thermal contact between the two bodies. Accordingly, a shrink fit is present at these corners 22, 32, which forcefully connects the heat sink 30 and the housing body 20. This allows heat to be transferred from the heat sink 30 to the housing body 20 and ultimately to the surroundings of the electric machine 5.

[0028] Furthermore, from the Fig. It is evident from Figure 1 that the rounded corners 32 of the heat sink 30 are arranged on a common first circular path and the rounded corners 22 of the housing body 20 are arranged on a common second circular path. The first and second circular paths are identical. However, it would also be conceivable that, for example, only the corners 32 of the heat sink 20 are arranged on a common circular path.

[0029] Furthermore, in Fig. Figure 1 shows that the housing body 20 is only shrunk onto the heat sink 30 at the rounded corners 22, 32, and the remaining areas of the housing body 20 are not in contact with the heat sink 30. These remaining areas include, in particular, the corners that are not designed as circular segments.

[0030] Not shown, for example, is a control unit for the electric machine 5, which may include a printed circuit board. The printed circuit board may be equipped with electronic components. These electronic components could be, for example, capacitors, semiconductor switches, coils, sensors, or energy storage devices, in order to enable a suitable electronic circuit for controlling and operating the electric machine 5.

[0031] The heat sink 20, for example, can be made primarily of aluminum. "Primarily made of aluminum" in this context means that the heat sink mainly consists of aluminum and contains only a small amount, for example in the single-digit percentage range, of one or more other materials. These other materials could be impurities, for example. However, these other materials could also be deliberately added to influence properties such as flexibility or durability, while other properties, such as thermal conductivity, should be hardly affected or not affected at all.

[0032] Furthermore, the heat sink 30 can, for example, be designed as a stamped part. Alternatively, it could also be manufactured using a deep-drawing and / or die-casting and / or bending process, or any combination of the aforementioned manufacturing processes. Similarly, the housing body 20 could, for example, be manufactured using a deep-drawing and / or die-casting process.

[0033] Fig. 2 shows a section through the device according to the invention. Fig. 1. The cut runs perpendicular to the line in Fig. 1 revealed axis AA' and to the in the Fig. The plane shown in Figure 1 depicts the device 10 with the housing body 20 and the heat sink 30. The rounded corners 32 of the heat sink 30 extend into a plane parallel to a main extension plane of the heat sink 30. The shrink fit between the housing body 20 and the heat sink 30 is also located in this parallel plane.

[0034] In an alternative embodiment, not shown in the illustration, the rounded corners 32 of the heat sink 30 could also lie only in the main plane of the heat sink 30. In this case, however, manufacturing the rounded corners 32 by turning would no longer be possible, which is why they would have to be produced, for example, by milling. Alternatively, the heat sink 30 with the corresponding rounded corners 32 in the main plane of the heat sink 30 could also be manufactured as a stamped part. A stamped part is understood to be a component that is manufactured by means of a stamping process. Typically, a plate is used as the starting element for this process, which is trimmed accordingly to obtain the desired stamped part in its final shape.

[0035] However, it is also conceivable that the cooling element 30 can be manufactured using a deep drawing or casting process or using a combination of the aforementioned manufacturing processes.

[0036] Fig. Figure 3 shows the heat sink of the device according to the invention. Fig. 1 and Fig. 2 in a perspective view.

[0037] The heat sink 30 is shown, which has the corresponding eight corners 31. Four of the eight corners 32 are designed as circular segments or cylindrical segments. The rounded corners 32 of the heat sink 30 extend into a plane parallel to a main extension plane of the heat sink 30.

Claims

[1] Device (10) with a housing body (20) for an electric machine (5), wherein the device (10) has a heat sink (30) which is arranged inside the housing body (20), and wherein the housing body (20) has a cross-section with eight corners (21) and the heat sink (30) has a cross-section with eight corners (32) as its basic shape, characterized by , that four corners (22) of the octagonal housing body (20) and four corners (32) of the octagonal heat sink (20) are each designed as a circular segment rounded and arranged in such a way that the housing body (20) is shrunk onto the heat sink (30) at these rounded corners (22, 32) for thermal contact between the heat sink (30) and the housing body (20). [2] Device (10) according to claim 1, characterized by , that the rounded corners (32) of the heat sink (30) extend into a plane parallel to a principal extension plane of the heat sink (30). [3] Device (10) according to claim 1 or 2, characterized by , that the rounded corners (32) of the heat sink (30) are arranged on a common first circular path and / or the rounded corners (22) of the housing body (20) are arranged on a common second circular path. [4] Device (10) according to any one of claims 1 to 3, characterized by , that the housing body (20) is only shrunk onto the heat sink (30) at the rounded corners (22, 32) and the remaining areas of the housing body (20) are not in contact with the heat sink (30). [5] Device (10) according to any one of claims 1 to 4, characterized by , that the corners (22) of the housing body (20) and / or the corners (32) of the heat sink (30) are designed in cross-section as alternating circular segments and non-circular segments. [6] Electric machine (5) with a device (10) according to any one of claims 1 to 5.

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