Method for manufacturing a housing part designed as a die-cast component for a housing for arranging an electric drive motor in a motor vehicle and housing for arranging an electric drive motor in a motor vehicle

Abstract

Method for manufacturing a die-cast component, which is a housing part (100) of a housing for arranging an electric traction motor in a motor vehicle, wherein the housing part (100) has a stator receiving area (110) for the electric traction motor and at least one mounting flange (120) for mounting power electronics switching the electric traction motor, wherein this housing part (100) is designed as a one-piece die-cast component with an integrated cooling system with which both the stator receiving area (110) and the mounting flange (120) can be cooled, and the integrated cooling system has at least one cooling channel (130) and at least one section (A) formed in the cooling channel (130) with a filigree cooling structure that locally increases the cooling capacity, comprising the steps: - Manufacturing a core (200) representing the cooling channel (130), which has a section (A') for forming the delicate cooling structure; - Inserting the core (200) into the cavity of a die-casting tool; - Die casting, in which a molten metal is forced into the cavity and the core (200) is surrounded by the molten metal; - Demolding of the die-cast component and removal of the core (200); wherein it is provided that the core (200) in section (A') is fitted with protruding metal pins (210) to form the delicate cooling structure, which then fuse with the molten metal at their protruding ends (212) during die casting and, after the core (200) is removed, protrude into the cooling channel (130).

Description

[0001] The invention relates to a method for manufacturing a die-cast component, wherein the component is a housing part of a housing for arranging an electric traction motor in a motor vehicle. The invention further relates to a housing for arranging an electric traction motor in a motor vehicle.

[0002] Key components of an electric vehicle drive system are the electric drive motor (electric motor, electric traction motor) and the power electronics (PE) that control this drive motor, which, for example, comprises one or more power electronic modules (PE modules) with power electronic components. This applies equally to vehicles with purely electric drive and vehicles with hybrid drive. Currently, the electric drive motor and the power electronics are installed in different locations within the vehicle and must be electrically connected via cables and wires.

[0003] The nearest German patent application, DE 10 2010 048 131 A1, describes an electric drive unit. The electric drive unit comprises a metal housing. A stator of an electric machine is inserted into the metal housing. An electrical circuit, which includes, for example, an inverter, is associated with the electric machine. The electrical circuit is arranged within a section of the circuit housing. Furthermore, a lubrication circuit with lubricating oil is provided. In addition to the lubrication circuit, the electric drive unit includes a cooling circuit in which cooling water circulates. The cooling water serves to cool the stator as well as the electrical circuit. The cooling circuit comprises several cooling channels along the outer surface of the metal housing, through which cooling water can flow circumferentially. The metal housing is preferably cast from aluminum. No further details regarding its manufacture are described.

[0004] For the state of the art, reference is also made to DE 198 17 333 C1, DE 103 19 129 A1, DE 10 2010 054 496 A1 and DE 11 2008 000 040 B4.

[0005] The invention is based on the objective of improving the state of the art and showing ways in which at least one disadvantage associated with the state of the art can be avoided or at least reduced.

[0006] This problem is solved by a method according to the invention for manufacturing a die-cast component according to the features of claim 1 and by a method according to the invention for manufacturing a die-cast component according to the features of claim 2. Claim 5 extends the invention to a housing according to the invention for arranging an electric drive motor in a motor vehicle. Preferred embodiments and configurations for all aspects of the invention are described analogously in the dependent claims and in the following explanations.

[0007] The housing according to the invention for arranging (at least) one electric drive motor in a motor vehicle, in particular a passenger car, comprises a housing part that has a stator mounting area for the electric drive motor and at least one mounting flange for attaching the power electronics that control the electric drive motor. This housing part is designed as a one-piece, i.e., manufactured in one piece, die-cast component with an integrated cooling system that cools both the stator mounting area and the mounting flange for the power electronics. It is a metallic die-cast component.

[0008] The invention has many advantages. On the one hand, the housing according to the invention enables the structural integration of the electric drive motor and power electronics, resulting, among other things, in optimized installation space, simpler assembly, and a reduction in electrical losses. On the other hand, the design of the housing according to the invention as a die-cast component, preferably as a weight-saving aluminum or magnesium die-cast component, enables series production, particularly in large series.

[0009] A major challenge in the structural assembly according to the invention is the dissipation of heat loss from the electric traction motor or its stator and the power electronics or their power electronic components. The power loss of the power electronics alone can reach 5 kW or more, and it must be noted that the power electronics or their power electronic components, unlike the stator of the electric traction motor, have very little heat capacity. Therefore, the housing according to the invention is designed to have an integrated cooling system that actively dissipates heat loss, cooling both the stator mounting area and thus the electric traction motor, as well as the mounting flange and thus the power electronics attached thereto. Preferably, this system is a water-cooled or...- a flow-through cooling system (water cooling), which in particular refers to an assembly of casting-integrated cooling channels. The casting-integrated cooling system does not require any additional installation space. The housing according to the invention thus offers the possibility of a high integration density.

[0010] The housing according to the invention is in particular a hybrid transmission housing for a motor vehicle with a hybrid drive, which is intended for the integration or structural combination of a vehicle transmission with an electric drive motor that is installed in or on the hybrid transmission housing.

[0011] The mounting flange is preferably formed on an outer surface of the stator mounting area and has at least one flat surface to which at least one LED module (such as an IGBT module) can be attached. Attachment is preferably achieved by screwing, which is why the flat surface can also be referred to as a mounting surface. Manufacturing the housing according to the invention as a die-cast component enables the formation of such a flat surface or mounting surface free of voids and ensures a low surface roughness, which is in particular less than 50 µm.

[0012] The cooling system is designed to include at least one annular cooling channel or cooling ring encircling the stator mounting area. Furthermore, the annular cooling channel is designed to extend between the stator mounting area and the mounting flange, and in this section is locally designed with a delicate cooling structure that increases cooling performance and exhibits surface area-enlarging and / or turbulence-promoting or -enhancing properties (with respect to the flowing cooling medium). The design of this delicate cooling structure is described below.

[0013] An inventive method for manufacturing a die-cast component, which is a housing part of a housing for arranging an electric drive motor in a motor vehicle and which, among other things, has an integrated cooling system with at least one cooling channel and at least one section formed in the cooling channel with a filigree cooling structure that locally increases the cooling performance, comprises at least the following steps: - Manufacturing a core that replicates the cooling channel and has (at least) a corresponding section for forming the delicate cooling structure; - Inserting the core into the cavity of a die-casting tool; - Die casting, in which a molten metal, in particular an aluminum or magnesium molten metal, is pressed into the cavity and the core (including the relevant section for forming the delicate cooling structure) is surrounded by the molten metal; - Demolding of the die-cast component (after prior solidification of the molten metal) and removal of the core, leaving a cooling channel in the die-cast component, which in at least one section is formed with a delicate cooling structure that locally increases the cooling performance.

[0014] The core is a so-called lost core. Preferably, it is a salt core. The salt core can be produced by casting, pressing, compaction, sintering, core shooting, or similar processes. The salt core is removed by rinsing.

[0015] To form the intricate cooling structure, the core is fitted with protruding metal pins (at one or both axial ends) in the relevant section. During die casting, these pins fuse with the molten metal at their axial ends, which protrude from the core surface (or are cast into the molten metal). After the core is removed from the inner wall or shell surface, these pins project into or through the cooling channel. These metal pins increase the surface area in the respective cooling channel section and have turbulence-promoting or -enhancing properties with respect to the flowing cooling medium, thereby locally increasing the cooling capacity in that section.

[0016] Preferably, the metal pins are made of aluminum (e.g., aluminum nails), which is particularly advantageous when molten aluminum is used for die casting (to produce an aluminum die-cast component). It is especially preferred that the aluminum material of the aluminum pins has a higher silicon content (Si content) than the molten aluminum used. A higher Si content results in a lower melting point, thus ensuring that the aluminum pins, or at least their protruding ends, fuse with the aluminum casting material during the casting process, resulting in sufficiently high strength and stability for operation.

[0017] Alternatively, to form the delicate cooling structure, the core in the corresponding section is provided with at least one metallic cooling fin structure, which has a flat base and cooling fins projecting from it in a comb-like fashion and extending into the interior of the core. After the core is removed, the cooling fins project into (or through) the cooling channel, and the flat base cast into the die-cast component can be used as a mounting flange, in particular as a screw-on surface for a power electronics module, and has a flat surface or area for this purpose. Preferably, the cooling fin structure used is made of aluminum, for which the above explanations regarding the aluminum pins apply analogously.

[0018] The previously explained design options for creating a delicate cooling structure in a cooling channel can also be combined.

[0019] The cooling channel in the die-cast component to be manufactured can be annular, preferably with the core used, in particular a salt core, being formed in one piece and having an annular shape corresponding to the cooling channel to be manufactured. A salt core with an annular shape can also be referred to as a salt core ring. The annular core or salt core has at least one corresponding section for forming a delicate cooling structure.

[0020] A method according to the invention serves to manufacture a housing part for a housing (or for use on a housing) for mounting an electric traction motor in a motor vehicle. The housing part has at least one, in particular cylindrical, stator mounting area for the electric traction motor and at least one mounting flange for attaching the power electronics that control the electric traction motor. This housing part is designed as a one-piece die-cast component with an integrated cooling system with which both the stator mounting area and the mounting flange can be cooled. Further developments and embodiments will become apparent from the preceding and following explanations and also from the figures.

[0021] The invention is explained in more detail below by way of example and in a non-restrictive manner with reference to the schematic and not to-scale figures. Fig. Figure 1 shows a side view of a hybrid transmission housing part. Fig. Figure 2 shows a section of a core used to manufacture the hybrid transmission housing part in Fig. 1 can be used. Fig. Figure 3 shows another possible embodiment of a core used to manufacture the hybrid transmission housing part in Fig. 1 can be used.

[0022] Fig. Figure 1 shows a hybrid transmission housing component for a hybrid transmission in a passenger car. The housing component 100 is a one-piece die-cast aluminum part. Reference numeral 110 designates a substantially cylindrical stator mounting area for an electric motor (electric machine or traction motor) to be arranged in or on the hybrid transmission housing. Reference numeral 120 designates a mounting flange, shown only schematically, for attaching the power electronics that control the electric traction motor. This flange is located outside the stator mounting area 110 on an outer surface 140 (not shown in detail). The mounting flange 120 includes, by way of example, a single flat surface that serves as a mounting surface for the power electronics.

[0023] During operation, both the electric traction motor in the stator mounting area 110 and the power electronics attached to the outer mounting flange 120 must be cooled to reliably dissipate the resulting heat loss. For this purpose, the housing part 100 has at least one annular cooling channel 130 surrounding the stator mounting area 110, through which a coolant can flow. The annular cooling channel 130, shown with dashed circle lines, has, for example, an inner ring diameter of 200 mm to 300 mm.

[0024] The annular cooling channel 130 also runs between the stator mounting area 110 and the mounting flange 120. In order to reliably dissipate both the waste heat from the electric traction motor and the waste heat from the power electronics in this section or circumferential section marked A, the cooling channel 130 is locally designed in this section A with a delicate cooling structure that increases the cooling capacity and has surface-enlarging and / or turbulence-promoting properties.

[0025] The cooling channel 130 is manufactured using a modified lost core 200, which is in particular a salt core suitable for die casting, which has a corresponding section or circumferential section A' for casting and thus forming the delicate cooling structure in the die casting process.

[0026] Fig. Figure 2 shows a first embodiment in which the core 200 in the corresponding section A' is fitted with protruding metal pins 210. These are, for example, aluminum pins. The metal pins 210 shown are, for example, formed with heads 212. The core 200 is formed, for example, as a monolithic block with small holes (created, for example, by drilling) into which the metal pins 210 are inserted, in particular such that the heads 212 do not rest on the surface but are freestanding, as shown. During casting (in the die-casting process), the heads 212 of the metal pins 210, which protrude from the surface of the salt core, fuse with the casting material (molten aluminum) or are cast in a form-fitting manner, with the heads being cast in an undercut shape. After the core 200 has been removed from the die-cast component, which is done in particular by rinsing, the metal pins 210 protrude into the cooling channel 130 in section A.

[0027] In contrast to the one in Fig. In the embodiment shown in 2, the metal pins 210 can also be arranged in the core 200 from both sides (i.e., from above and below as shown, or optionally only from below) and / or arranged in such a way that they protrude with both axial ends if they have a corresponding axial length.

[0028] Fig.Figure 3 shows a second embodiment in which the core 200 in the corresponding section A' is equipped with a metallic cooling fin structure 220 to form the delicate cooling structure. The cooling fin structure 220, primarily made of aluminum, has a flat base 222 and cooling fins 224 projecting from it in a comb-like fashion. During casting (in the die-casting process), the base 222 of the cooling fin structure 220 is form-fittingly encased by the casting material (molten aluminum) and is thereby cast in an undercut shape and / or fused with the casting material. After the core 200 is removed from the die-cast component, the cooling fins 224 project into the cooling channel 130. The flat base 222, with its planar surface, can simultaneously serve as a mounting flange 120 for the surface mounting of the power electronics or the LE modules. The dashed line represents a section of the outer surface area of ​​outer surface 140 or 140.An outer surface section of the stator mounting area 110 on the housing part 100 or die-cast component to be manufactured is shown. Within this surface section, the outer or rear side of the base 222 of the cooling fin structure 220 forms the mounting flange 120 for attaching the power electronics. Similarly, several cooling fin structures 220 can be used, which may be identical or different in design. Reference symbol list 100 housing parts 110 Stator mounting area 120 Mounting flange 130 Cooling channel 140 outdoor area 200 core 210 metal pin 212 head 220 cooling fin structure 222 sockets 224 cooling fins Section A (cooling channel) Section A (core)

Claims

[1] Method for manufacturing a die-cast component, which is a housing part (100) of a housing for arranging an electric traction motor in a motor vehicle, wherein the housing part (100) has a stator receiving area (110) for the electric traction motor and at least one mounting flange (120) for mounting power electronics switching the electric traction motor, wherein this housing part (100) is designed as a one-piece die-cast component with an integrated cooling system with which both the stator receiving area (110) and the mounting flange (120) can be cooled, and the integrated cooling system has at least one cooling channel (130) and at least one section (A) formed in the cooling channel (130) with a filigree cooling structure locally increasing the cooling capacity, comprising the steps: - Manufacturing a core (200) representing the cooling channel (130) which has a section (A') for forming the delicate cooling structure; - Inserting the core (200) into the cavity of a die-casting tool; - Die casting, in which a molten metal is forced into the cavity and the core (200) is surrounded by the molten metal; - Demolding of the die-cast component and removal of the core (200); wherein it is provided that the core (200) in section (A') is fitted with protruding metal pins (210) to form the delicate cooling structure, which then fuse with the molten metal at their protruding ends (212) during die casting and, after the core (200) is removed, protrude into the cooling channel (130). [2] Method for manufacturing a die-cast component, which is a housing part (100) of a housing for arranging an electric traction motor in a motor vehicle, wherein the housing part (100) has a stator receiving area (110) for the electric traction motor and at least one mounting flange (120) for mounting power electronics switching the electric traction motor, wherein this housing part (100) is designed as a one-piece die-cast component with an integrated cooling system with which both the stator receiving area (110) and the mounting flange (120) can be cooled, and the integrated cooling system has at least one cooling channel (130) and at least one section (A) formed in the cooling channel (130) with a filigree cooling structure locally increasing the cooling capacity, comprising the steps: - Manufacturing a core (200) representing the cooling channel (130) which has a section (A') for forming the delicate cooling structure; - Inserting the core (200) into the cavity of a die-casting tool; - Die casting, in which a molten metal is forced into the cavity and the core (200) is surrounded by the molten metal; - Demolding of the die-cast component and removal of the core (200); wherein it is provided that the core (200) in section (A') is equipped with at least one metallic cooling fin structure (220) to form the delicate cooling structure, which has a flat base (222) and cooling fins (224) projecting from it in a comb-like manner, and that after removal of the core (200) the cooling fins (224) project into the cooling channel (130) and the flat base (222) on the die-cast component can be used as a mounting flange (120) for mounting the power electronics and has a flat surface for this purpose. [3] Method according to claim 1 or 2, characterized by , that an aluminium melt is used for die casting, wherein the metal pins (210) or the cooling fin structure (220) are formed from an aluminium material which has a higher silicon content than the aluminium melt used. [4] Method according to any of the preceding claims, characterized by , that the cooling channel (130) to be produced is annular and that the core (200) used is formed in one piece and has a corresponding annular shape. [5] Housing for arranging an electric traction motor in a motor vehicle, comprising a housing part (100) having a stator receiving area (110) for the electric traction motor and at least one mounting flange (120) for mounting power electronics switching the electric traction motor, wherein this housing part (100) is designed as a one-piece die-cast component with an integrated cooling system with which both the stator receiving area (110) and the mounting flange (120) can be cooled, wherein the cooling system has at least one annular cooling channel (130) circumferencing the stator receiving area (110), which also runs between the stator receiving area (110) and the mounting flange (120) and in this section (A) is locally designed with a filigree cooling structure that increases the cooling performance and has surface-enlarging and / or turbulence-promoting properties, wherein the delicate cooling structure is formed either by metal pins (210) which are cast into the housing part (100) at their ends during the die-casting process, so that they project from the inner surface of the cooling channel (130) into the cooling channel (130), or by at least one metallic cooling fin structure (220) which has a flat base (222) cast into the housing part (100) during the die-casting process and cooling fins (224) extending from it in a comb-like manner and projecting into the cooling channel (130), wherein the cast-in flat base (222) of the metallic cooling fin structure (220) has a flat surface area which can also be used as a mounting flange (120) for the planar mounting of the power electronics. [6] Housing according to claim 5, characterized by that it is a hybrid gearbox housing.

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