DE102022212476A1 - Cooling system with housing-integrated heat exchanger section and electric drive unit with the cooling system - Google Patents

Abstract

A cooling system 1 for an electric drive unit 26 is proposed, with a first and a second cooling circuit 101, 102 for dissipating heat energy from at least one heat source 3 of the electric drive unit 26, with a housing section 7 for receiving the at least one heat source 3, wherein the housing section 7 and/or the heat source 3 defines a main axis 100, with a heat exchanger section 2 for exchanging heat between the first and the second cooling circuit 101, 102, wherein the heat exchanger section 102 is arranged on an axial end face of the housing section 7 with respect to the main axis 100, wherein the heat exchanger section 2 is formed by a partition 12 and a housing cover 11 fastened to the housing section 7, wherein the partition 12 divides a cavity 13 formed between the housing section 7 and the housing cover 11 into a first and a second coolant space 14a, 14b, wherein the first cooling circuit 101 is fluidically connected to the first coolant chamber 14a and the second cooling circuit 102 is fluidly connected to the second coolant chamber 14b.

Description

The invention relates to a cooling system for an electric drive unit with the features of the preamble of claim 1. Furthermore, the invention relates to an electric drive unit with the cooling system.

Cooling systems are known, particularly for electric vehicles, which dissipate heat loss in the drive and electronic components during operation and when charging the battery. Such cooling systems generally have several cooling circuits, some of which can be thermally coupled to form a so-called thermal management system. For example, there is a cooling circuit with a water-glycol mixture, via which heat energy is dissipated to the environment. Another cooling circuit includes a heat pump/AC compressor for air conditioning the passenger compartment and/or to support heat dissipation from the components. In some cooling systems, a third coolant circuit is used to dissipate heat from the lubricating and/or cooling oil system of a transmission. The heat is transferred between the individual cooling circuits by means of one or more heat exchangers, which are usually mounted as plate heat exchangers in standard form on the outside of a housing or on a separate module or console. The heat exchanger, especially screw connections, cover and housing, is often sealed using liquid sealants that are applied to the flange surfaces before assembly and are distributed during assembly by the screwing forces. Alternatively, separate seals are also known that are inserted between the flange surfaces.

For example, the publication EN 10 2019 212 118 A1 an annular heat exchanger, in particular for an axial front-side arrangement on an electrical machine, with a cooling channel ring which has an axial underside and an axial top side, and with a connection plate arranged on the underside of the cooling channel ring, wherein the cooling channel ring has on its underside an axially open inlet channel extending in the circumferential direction for guiding a coolant and a separate, axially open outlet channel extending in the circumferential direction for guiding the coolant. The cooling channel ring has on its top side a plurality of axially open cooling structures which are adjacent in the circumferential direction and through which the coolant can flow, wherein the cooling channel ring has an inlet opening for each cooling structure which fluidly connects the inlet channel through the cooling channel ring to the respective cooling structure. In addition, the cooling channel ring has an outlet opening for each cooling structure which fluidly connects the outlet channel through the cooling channel ring to the respective cooling structure, wherein the connection plate axially covers the inlet channel and the outlet channel.

The publication EN 10 2020 214 829 A1 discloses an electrical machine comprising a housing, a stator arranged in the housing and fixedly connected thereto, and a rotor arranged in the housing, which is arranged on a rotor shaft and is rotatably mounted relative to the stator about the axis of rotation of the rotor and the rotor shaft, wherein the housing has at least one first coolant channel of a first cooling circuit in the region of the stator and at least one second coolant channel of a second cooling circuit is arranged in the housing in the region of the stator, wherein the housing of the electrical machine forms a heat exchanger between the first cooling circuit and the second cooling circuit.

The invention has for its object to provide a cooling system of the type mentioned above, which is characterized by a particularly compact and cost-effective design.

This object is achieved by a cooling system having the features of claim 1 and by an electric drive unit having the features of claim 15. Further features and advantages as well as effects of the invention are described in the subclaims and the description with the figures.

The subject matter of the invention is a cooling system which is designed and/or suitable for an electric drive unit. In particular, the cooling system serves to implement fluid cooling, preferably liquid cooling, of one or more components of the electric drive unit.

For this purpose, the cooling system has a first and a second cooling circuit, which are designed and/or suitable for dissipating heat energy from at least or exactly one heat source of the electric drive unit. In principle, the heat source is designed as a drive component and/or electronic component of the electric drive unit. For example, the drive component can be designed as an electric machine, a gear, a bearing or the like. For example, the electronic component can be designed as power electronics, in particular an inverter, or a DC-DC converter or a DC-AC converter or the like, or an electrical energy storage device (battery). Preferably, the heat source is connected to the first The first and/or second cooling circuits are thermally coupled and/or fluidically integrated. Optionally, other devices to be cooled, e.g. heat pumps, air conditioning compressors or similar, can also be connected to the first and/or second cooling circuits. Optionally, thermal energy is transported to a cooler via the first and/or second cooling circuits and released into the environment there. The first and second cooling circuits are preferably fluidically separated from one another. A first coolant can thus circulate along the first cooling circuit and a second coolant along the second cooling circuit. For example, one coolant can be a cooling liquid, preferably a water-glycol mixture, and the other coolant can be a coolant and lubricant, preferably an oil.

The cooling system has a housing section which is designed and/or suitable for accommodating the at least one heat source of the electric drive unit. The housing section defines a main axis which is defined, for example, by a longitudinal axis, an axis of symmetry, an axis of rotation or the like of the housing section or of a drive or electronic component arranged in the housing section. The main axis is preferably defined by an axis of rotation of a drive or gear shaft of the electric drive unit.

The cooling system has a heat exchanger section which is designed and/or suitable for exchanging heat between the first and second cooling circuits. The heat exchanger section preferably serves to transfer thermal energy from the cooling circuit with a higher temperature to the cooling circuit with a lower temperature. The thermal energy within the heat exchanger section is particularly preferably transferred from one coolant, in particular the cooling and/or lubricating oil, to the other coolant, in particular the cooling liquid. In particular, the first and second cooling circuits are thermally coupled to one another in sections via the heat exchanger section. The first cooling circuit is preferably coupled and/or fluidically connected on one side of the heat exchanger section and the second cooling circuit on the other side of the heat exchanger section.

The heat exchanger section is arranged on an axial end face of the housing section in relation to the main axis. In principle, the heat exchanger section can be designed as a separate component which is connected to the housing section in a form-fitting and/or force-fitting manner. Alternatively, however, the heat exchanger section is integrated or partially integrated into the housing section.

Within the scope of the invention, it is proposed that the heat exchanger section is formed by a partition wall and a housing cover attached to the housing section, wherein the partition wall divides a cavity formed between the housing section and the housing cover into a first and a second coolant space. The first cooling circuit is fluidically connected to the first coolant space and the second cooling circuit is fluidly connected to the second coolant space. Thus, an indirect heat transfer between the two cooling circuits is realized through the partition wall. In other words, the heat exchanger section is designed as a so-called recuperator. Preferably, the housing section, the partition wall and the housing cover are connected to one another in a fluid-tight manner in a joining plane, which in particular corresponds to a radial plane of the main axis. In particular, the partition wall and the housing cover are mounted to the housing section in a form-fitting and/or force-fitting and/or material-fitting manner. For example, the partition wall and the housing cover are mounted to the housing section via a common screw connection.

The advantage of the invention is that by integrating the heat exchanger section into the housing section, a cooling system is proposed which has a high degree of integration and accordingly requires little installation space and a short line length or piping. Furthermore, a heat exchanger is proposed which is significantly more cost-effective and compact in comparison to known plate heat exchangers. Furthermore, by integrating the heat exchanger section into the housing section, a visually appealing design of the housing section can be achieved.

In a specific embodiment of the invention, it is provided that the housing section and/or the housing cover has a cooling channel structure, wherein the partition wall interacts with the cooling channel structure in such a way that one or more cooling channels are formed in the first and/or second coolant chamber. In particular, the cooling channel structure serves to form a flow path for the coolant of the first or second cooling circuit. In particular, a cooling channel structure is to be understood as a structuring of the surface along which the respective coolant is guided in a targeted manner within the respective coolant chamber from a coolant supply line to a coolant return line. For example, the cooling channel structure can be formed by one or more depressions and/or elevations, wherein the partition wall is arranged between the housing section and the housing cover in such a way that the cooling channel structure is at least partially covered and/or an at least partially closed cooling channel is formed between the coolant flow and the coolant return. In the simplest embodiment, the partition wall is flat, with the cooling channels being defined exclusively by the cooling channel structure. A heat exchanger section is thus proposed which is characterized by a particularly simple and robust construction.

In an alternative or optionally additional embodiment, it is provided that the partition wall has a shaft section which is axially supported on the housing section and/or the housing cover to form a plurality of cooling channels.

In particular, the coolant channels of the first and second cooling circuits are formed alternately by the shaft section. Preferably, the partition wall is supported on the housing section and/or the housing cover in the area of the wave crests and/or wave troughs, with a cooling channel being formed in the first or second coolant space between adjacent wave flanks. Preferably, the shaft section extends substantially in the entire cavity, so that the cooling channels are evenly distributed in the cavity. In other words, the entire cavity is divided by cooling channels that are evenly spaced from one another and/or of the same size. Particularly preferably, the shaft section has a wave-shaped, in particular sinusoidal, cross-sectional profile. Particularly preferably, the shaft section is designed such that the cooling channels extend in the same direction and/or parallel to one another. A heat exchanger section is thus proposed which is characterized by an even distribution of cooling channels and thus by an even or large-area heat transfer.

In a further specification, it is provided that the wave height of the wave section corresponds at least or exactly to an axial extension of the cavity, so that the wave section is axially supported and/or rests within the cavity at least in the area of the wave troughs and/or the wave crests. In principle, the wave section can be arranged in the axial direction with a small axial play within the cavity, so that deformations due to pressure fluctuations and/or temperature fluctuations in the coolant spaces can be compensated in order to ensure a permanent flow through the cooling channels.

In a further specification, it is provided that the shaft section is axially supported within the cavity at least on the side of the cooling circuit with the lower pressure. This makes it possible to reliably compensate for deformations caused by pressure fluctuations or pressure differences between the two coolant circuits in a particularly advantageous manner, so that the partition wall does not experience overloading as a result of excessive mechanical stresses under the required operating conditions.

In an alternative embodiment, it is provided that the wave height of the wave section has an excess and/or is designed to be elastically deformable at least in sections, so that the partition wall within the cavity is axially supported with a prestress in the axial direction in the area of the wave troughs and the wave crests. In other words, the wave section is axially supported on the housing section on one side and on the cover on the other side under a prestress. Preferably, the partition wall, in particular in the area of the wave troughs and/or the wave crests, is slightly deformed when the housing cover is assembled, so that the partition wall is supported in the axial direction on the housing section and the housing cover in a form-fitting and/or force-fitting manner, in particular by generating the prestressing force. Alternatively or optionally, the wave section, in particular at least in the area of the wave crests, has an elastic coating to ensure elastic deformation and the tightness requirements. The elastic coating is preferably made of a material with limited elastic deformability, such as a rubber coating. The axial support of the wave troughs and wave crests prevents cross-flow of the first and second coolants within the respective coolant chamber. This ensures that the coolant of the first and second cooling circuits flows exclusively along the respective cooling channels in exactly one flow direction and heat dissipation is improved.

In a further development, it is provided that a distance between the individual cooling channels is at least or exactly 2 mm. In other words, the distance between two adjacent wave crests or between two adjacent wave troughs is at least or exactly 2 mm. Preferably, the distance is less than 2 mm, preferably less than 1.5 mm, in particular less than 1 mm. Particularly preferably, a high flow velocity is achieved by the small distance between the individual cooling channels, whereby the heat transfer performance of the heat exchanger is improved. On the one hand, this makes it possible to On the one hand, an increase in the heat exchange area between the two cooling circuits and, on the other hand, a turbulent flow can be achieved.

In a further embodiment, it is provided that the cooling channels on the side of the first and/or the second coolant chamber are designed to generate and/or support a turbulent flow. The cooling channels, in particular the partition wall and/or the cooling channel structure, can preferably have one or more disruptive elements, disruptive contours or the like, which are designed to generate turbulence in the respective coolant when flowing in and/or around it. Alternatively or optionally in addition, the channel cross sections of the respective cooling channel can be reduced in sections in order to generate turbulence in the respective coolant. By deliberately generating turbulent flows, the heat transfer of the heat exchanger can be specifically influenced, preferably increased.

In a further design, it is provided that the cavity has a circular or arcuate configuration. The shape of the cavity can in principle be designed as desired and can be adapted to the design conditions. In order to enable the largest possible heat exchange surface, however, a circular or arcuate configuration is preferably useful. The cavity preferably extends coaxially and/or concentrically to the main axis on the axial front side of the housing section. In particular, with an arcuate configuration, the cavity can have the shape of a circular ring segment of at least 45 degrees, preferably at least 90 degrees, in particular at least 180 degrees. Alternatively, with a circular configuration, the cavity can be designed to run all the way around the main axis. Accordingly, the partition wall and/or the housing cover can have a shape that is geometrically similar to and/or complementary to the cavity. The cooling channels of the first and/or second coolant chamber are particularly preferably aligned in the circumferential direction with respect to the main axis. The cooling channels particularly preferably extend in the circumferential direction with respect to the main axis in the same direction and/or parallel to one another. It is therefore proposed that a heat exchanger section be integrated into the housing section in a particularly simple and space-saving manner by utilizing the axial end face.

In a further specific embodiment, it is provided that the partition wall has a circumferential sealing section which is designed and/or suitable for fluid-tight sealing of the cavity. For this purpose, the sealing section lies axially between the housing section and the housing cover in a sealing manner in an edge region surrounding the cavity. In particular, the housing section and the housing cover are supported against one another in the edge region indirectly via the sealing section. Preferably, the edge region is to be understood as a flat screw connection and/or sealing surface of the housing section and the housing cover, which preferably extends in a radial plane of the main axis. Particularly preferably, the sealing section extends continuously all the way around in the edge region, so that a continuous sealing line is formed between the housing section and the housing cover. The sealing section preferably adjoins the shaft section in a flange-like manner. A partition wall is thus proposed which can be installed in a simple manner and at the same time ensures a high level of tightness between the housing section and the housing cover.

In a further specification, it is provided that the sealing section is formed as a flat material section which is provided with a sealing means on both sides. The sealing section is preferably designed as a sealing flange extending within a radial plane of the main axis. The sealing means can be designed, for example, as a sealing coating of the sealing section, for example a rubber coating. Alternatively, however, the sealing means can also be formed by separate seals which are mounted on both sides of the material section in a form-fitting and/or force-fitting and/or material-fitting manner. A sealing section is thus proposed which ensures sealing of the cavity in a simple manner.

In a further embodiment, it is provided that the partition wall is designed as a deep-drawn component. In particular, the partition wall is made of a metal sheet in deep-drawing quality, preferably a metal sheet with a sheet thickness of less than 0.7 mm, which is preferably produced and/or structured by forming, in particular by deep-drawing, or can be produced in a deep-drawing process. For example, the metal sheet can be made of copper, aluminum, steel or their alloys. The housing section and/or the housing cover are particularly preferably designed as a cast part. Alternatively, it is provided that the partition wall is also designed as a cast part. A partition wall is thus proposed which is characterized by simple and cost-effective production and a low component weight. In addition, the heat transfer can be significantly influenced by a suitable choice of material and the wall thickness or sheet thickness.

In a further embodiment of the invention, it is provided that the heat exchanger section has a first flow connection and a first return connection, which are each designed and/or suitable for connecting the first coolant chamber to the first cooling circuit. The heat exchanger section also has a second flow connection and a second return connection, which are each designed and/or suitable for connecting the second coolant chamber to the second cooling circuit. In particular, the two flow connections each form a coolant flow and the two return connections each form a coolant return. Preferably, the first flow connection and the first return connection are integrated into the housing section and the second flow connection and the second return connection are integrated into the housing cover. Preferably, the first flow connection and the first return connection or the second flow connection and the second return connection are spaced apart from one another in the circumferential direction and/or are fluidically shielded from one another by a separating section. Particularly preferably, a first flow path of the first cooling circuit within the first coolant chamber runs from the first flow connection to the first return connection and a second flow path of the second cooling circuit within the second coolant chamber runs from the second flow connection to the second return connection.

According to this embodiment, it is provided that the first flow connection and the second return connection are arranged axially opposite one another in relation to the main axis and that the second flow connection and the first return connection are arranged axially opposite one another in relation to the main axis. A heat exchanger is thus proposed which is designed according to the countercurrent principle. For example, the first coolant can flow within the first working chamber in a circumferential direction around the main axis along the first flow path and the second coolant can flow within the second working chamber in an opposite direction around the main axis along the second flow path. A heat exchanger section is thus proposed which is characterized by optimal performance. Alternatively, however, it can also be provided that the two flow connections and the two return connections are each arranged axially opposite one another, so that a heat exchanger section with a cocurrent principle is realized.

In a further specific embodiment, it is provided that the first flow path of the first cooling circuit and/or the second flow path of the second cooling circuit is deflected at least once in the circumferential direction in relation to the main axis within the cavity. In particular, the first and/or second flow path can be deflected at least or exactly once in a range between 90° and 180°. Alternatively or optionally in addition, the first and/or second flow path have a meandering, labyrinth-shaped, turned or zigzag-shaped flow pattern. For this purpose, the first and/or second working chamber can be divided in the circumferential direction by at least or exactly one separating section into at least or exactly two flow sections, which are connected to one another at the end by a deflection section. Preferably, the first or second flow connection is arranged in an inlet region of the first flow section and the first or second return connection is arranged in an outlet region of the second flow section. In other words, the first or second flow path runs from the first or second flow connection via the first flow section, the deflection section and the second flow section to the first or second return connection. A heat exchanger section is thus proposed in which the exchange surface remains the same between the first and second coolant chambers compared to the previously described embodiments, but the flow velocity is increased, in particular doubled.

Furthermore, in another possible embodiment, it is conceivable that only the flow path of one of the two cooling circuits within the cavity is deflected at least once in the circumferential direction in relation to the main axis, whereas the other flow path of the other cooling circuit only has one flow direction. In this embodiment, a hybrid form between countercurrent and cocurrent principles results, since on one half the coolants flow in opposite directions and on the other half in the same direction. For example, the first flow path of the first cooling circuit, preferably the cooling and/or lubricating oil circuit, can be deflected at least once in order to utilize the physical properties of the first coolant. In contrast, the second flow path of the second cooling circuit runs directly in the circumferential direction, in particular without changing the flow direction. This can be particularly useful if the heat capacities of the two fluids are significantly different in order to achieve higher heat transfer values.

Another subject of the invention relates to an electric drive unit for an electric or hybrid vehicle, with the cooling system as already described above. In particular, the vehicle has at least two axles sen, of which at least one can be driven by the electric drive unit. The electric drive unit essentially has an electric machine, power electronics and an electric energy storage unit, wherein the cooling system serves to cool the electric machine and/or the power electronics and/or the energy storage unit. Optionally, the electric drive unit can have further components, such as a gear, bearings, heat pump, DC-DC converter, DC-AC converter, combustion engine, etc., wherein the cooling system is designed and/or suitable for cooling one or more of the components.

• 1 eine stark schematisierte Darstellung eines Kühlsystems mit zwei getrennten Kühlkreisläufen;
• 2 eine axiale Ansicht eines Wärmetauscherabschnittes des Kühlsystems;
• 3 eine Schnittdarstellung des Wärmetauscherabschnittes aus 2;
• 4 eine Detailansicht der Schnittdarstellung aus 3;
• 5 eine alternative Ausführung des Wärmetauscherabschnittes in einer axialen Ansicht;
• 6 eine dreidimensionale Darstellung einer elektrischen Antriebseinheit mit dem Kühlsystem;
• 7 eine Detailansicht des Wärmetauscherabschnittes des Kühlsystems aus 6;
• 8 eine Schnittdarstellung der elektrischen Antriebseinheit aus 6.

The present invention is explained further below with reference to drawings.

• 1 a highly schematic representation of a cooling system with two separate cooling circuits;
• 2 an axial view of a heat exchanger section of the cooling system;
• 3 a sectional view of the heat exchanger section 2 ;
• 4 a detailed view of the sectional view 3 ;
• 5 an alternative embodiment of the heat exchanger section in an axial view;
• 6 a three-dimensional representation of an electric drive unit with the cooling system;
• 7 a detailed view of the heat exchanger section of the cooling system 6 ;
• 8th a sectional view of the electric drive unit from 6 .

1 shows a cooling system 1 as an embodiment of the invention in a highly schematic representation. The cooling system 1 has a first cooling circuit 101 and a second cooling circuit 102, which are thermally coupled to one another via a heat exchanger section 2. The two cooling circuits 101, 102 are fluidically separated from one another.

The first cooling circuit 101 serves to cool a heat source 3, wherein the first cooling circuit is thermally connected to the heat source 3 for this purpose or the heat source 3 is fluidically integrated into the first cooling circuit 101. The first cooling circuit 101 is designed as an active cooling circuit, wherein the first cooling circuit 101 has a first coolant pump 4 for this purpose, which conveys a first coolant. For example, the first coolant can be a cooling and/or lubricating oil.

The second cooling circuit 102 can also be designed as an active cooling circuit, wherein the second cooling circuit 102 has a second coolant pump 5 for this purpose, which conveys a second coolant. For example, the second coolant can be a coolant, in particular a water-glycol mixture. The two cooling circuits 101, 102 are thermally coupled to one another within the heat exchanger section 2 in such a way that thermal energy transported by the first cooling circuit 101 is transferred to the second cooling circuit 102 by indirect heat transfer. The second cooling circuit 102 can have a cooler 6 in order to release the thermal energy to an environment. Alternatively, however, instead of the cooler 6, another heat source to be cooled, a heat pump or the like, can also be arranged. It is also conceivable to arrange another heat exchanger section, not shown, in front of the cooler 6 in order to incorporate another cooling circuit, not shown.

The cooling system 1 has a housing section 7 in which the heat source 3 is arranged. The housing section 7 and/or the heat source 3 define a main axis 100, wherein the heat exchanger section 2 is arranged on an axial end face of the housing section 7 with respect to the main axis 100.

The heat exchanger section 2 has a first flow connection 8a and a first return connection 9a on one side, wherein the first cooling circuit 101 is fluidically coupled to the heat exchanger section 2 via the first flow connection 8a and the first return connection 9b. Furthermore, the heat exchanger section 2 has a second flow connection 8b and a second return connection 9b on the other side, wherein the second cooling circuit 102 is fluidically coupled to the heat exchanger section 2 via the second flow connection 8b and the second return connection 9b. For example, the first flow connection 8a and the second return connection 9b are arranged axially opposite one another and the first return connection 9a and the second flow connection 8b are arranged axially opposite one another, so that a countercurrent principle is implemented.

2 shows a concrete embodiment of the heat exchanger section 2 in an axial view with respect to the main axis 100. The heat exchanger section 2 is arranged coaxially and/or concentrically to the main axis 100 and is ring-shaped, with the two flow connections 8a, 8b, here only the second flow connection 8b is shown, and the two return connections 9a, 9b, here only the second Return connection 9b shown, are arranged in such a way that a flow path S1, S2 running between the respective flow connection 8a, 8b and the respective return connection 9a, 9b, here only the second flow path S2 shown, runs in the circumferential direction with respect to the main axis 100 almost over the entire circumference of the heat exchanger section 2. For optimum performance, the countercurrent principle is advantageously used, as in 1 described, so that the flow direction of the first flow path S1 is oriented opposite to the flow direction of the flow path S2.

For this purpose, the first flow connection 8a and the first return connection 9a as well as the second flow connection 8b and the second return connection 9b are arranged adjacent to one another on an underside of the heat exchanger section 2 in a proper assembly state of the heat exchanger section 2, wherein a partition wall 10, as indicated schematically, is arranged between the first flow connection 8a and the first return connection 9a and between the second flow connection 8b and the second return connection 9b, which separates the connections 8a, 8b, 9a, 9b from one another on the underside of the heat exchanger section 2.

3 shows the heat exchanger section 2 in the intended mounting state on the housing section 7 in a sectional view AA, as in 2 indicated. The heat exchanger section 2 is formed by a housing cover 11 and a partition wall 12, wherein the partition wall 12 is arranged in the axial direction with respect to the main axis 100 between the housing cover 11 and the housing section 7 and divides a cavity 13 formed between the housing cover 11 and the housing section 7 into a first and a second coolant chamber 14a, 14b. As with a classic heat exchanger, this creates two coolant chambers 14a, 14b that are fluidically separated from one another and exchange heat with one another. The cavity 13 is designed as an annular space surrounding the main axis 100, which is delimited or interrupted in the circumferential direction by the partition wall 10 in the area of the connections 8a, 8b, 9a, 9b.

The partition wall 12 has a shaft section 15 and a sealing section 16, wherein the partition wall 12 with the shaft section 15 is arranged within the cavity 13 and with the sealing section 16 in an edge region 17 of the housing section 7 and the housing cover 11 that surrounds the cavity 13. The shaft section 15 has a wave-shaped cross-sectional profile that creates a wave-shaped volume on both sides through which the first and second coolants can flow. The shaft section 15 is supported in an axial direction with respect to the main axis 100 on the housing section 7 and/or the housing cover 11 in a form-fitting and/or force-fitting manner.

The sealing section 16 is directly connected to the shaft section 15 in the radial direction with respect to the main axis 100, the sealing section 16 forming a flange that surrounds the shaft section 15. The sealing section 16 is sealingly located all the way around between the housing section 7 and the housing cover 11 in the edge region 17, so that the cavity 13 or the two coolant chambers 14a, 14b are sealed in a fluid-tight manner. For example, the sealing section 16 is continuous or uninterrupted all the way around the main axis 100, so that the housing cover 11 is supported indirectly on the housing section 7 via the sealing section 16. The housing cover 11 is fastened to the housing section 7 in the axial direction with respect to the main axis 100 via a plurality of fastening means 18, for example screws, wherein the sealing section 16 is held in a force-fitting and/or form-fitting manner between the housing cover 11 and the housing section 7.

The design of the partition wall 12 is conceivable using different materials and different manufacturing processes. However, it is preferably proposed to produce the partition wall 12 as a thin steel sheet with a sheet thickness of less than 0.7 mm by means of deep drawing. A partition wall 12 is thus proposed which can be produced inexpensively and has a low component weight. Furthermore, a partition wall 12 is proposed which on the one hand divides the cavity 13 into two separate coolant spaces 14a, 14b and at the same time ensures a fluid-tight seal between the housing cover 11 and the housing section 7 or a fluid-tight seal of the cavity 13.

4 shows a detailed view of the section AA of the 3 . The shaft section 15 forms several cooling channels 18a, 18b on both sides, which are arranged alternately one after the other in the radial direction. The cooling channels 18a, 18b extend in the circumferential direction with respect to the main axis 100 parallel and/or in the same direction to one another. The cooling channels 18a, 18b each define the flow path S1, S2 for the first and second coolant, respectively, as shown in 2 The first and second cooling channels 18a, 18b are spaced apart from each other by as small a distance A as possible, e.g. less than 2 mm, in order to obtain the highest possible flow velocity. This allows the heat transfer performance of the heat exchanger section 2 can be improved.

Furthermore, the shaft section 15 has a wave height H which is only slightly smaller than or equal to the axial extent of the cavity 13. A design of the wave height H and the wave shape which enables prestressing is particularly advantageous, so that the shaft section 15 rests against the housing section 7 in the area of the wave crests 19 and/or against the housing cover 11 in the area of the wave troughs 20 in an axial direction with a force fit. This makes it possible to avoid cross-flow of the first or second coolant between the individual cooling channels 18a, 18b. Care must be taken to ensure that the stresses in the material are not overloaded under the required operating conditions.

The sealing section 16 is designed as a flat material section which extends in the wheel area 17 parallel to a screw connection or sealing surface of the housing section 7 and the housing cover 11. For example, the sealing section 16 extends in a radial plane of the main axis 100. The sealing section 16 is provided on both sides with a sealing means 21 which ensures a fluid-tight seal between the housing section 7 and the housing cover 11. For example, the sealing means 21 is designed as an elastomer seal arranged on both sides of the sealing section 16 which has a sealing line running circumferentially around the main axis 100.

Optionally, it can be provided that the first and/or the second coolant chamber 14a, 14b is designed according to the properties of the respective coolant by means of disruptive elements and/or a reduction in the channel cross-sections in such a way that a turbulent flow is provoked to increase the heat transfer. In particular, the cooling and lubricating oil is at a disadvantage compared to the water-based coolant, since a turbulent flow only develops at high flow speeds.

5 shows an alternative embodiment of the heat exchanger section 2 in an axial view with respect to the main axis 100. Here, the cavity 13 or at least one of the two coolant chambers 14a, 14b is divided centrally in the circumferential direction by a separating section 22, which in the embodiment shown divides the first coolant chamber 14a into a first and a second flow section 23a, 23b, which are fluidically connected to one another via a deflection section 24.

The first flow connection 8a is arranged in an inlet region of the first flow section 23a and the first return connection 9a is arranged in an outlet region of the second flow section 23b, so that the first flow path S1 runs from the first flow connection 8a via the first flow section 23a in the circumferential direction to the deflection section 24, is deflected by essentially 180 degrees in the deflection section 24 and runs in the opposite direction via the second flow section 23b to the first return connection 9a. The exchange area remains the same, but the flow speed doubles.

In principle, the flow path S1, S2 can be diverted for both sides. However, it is also conceivable to divert only one of the two flow paths S1, S2, e.g. only for the cooling and lubricating oil, while the other flow path S1, S2 only flows in one direction. This design results in a hybrid between countercurrent and cocurrent principles, since on one half the two coolants flow in opposite directions and on the other half in the same direction.

In a further optional embodiment, it can be provided that the housing section 7 and/or the housing cover 11 has a cooling channel structure 25 on a side facing the cavity 13, which cooperates with the partition wall 12 to form or co-form the cooling channels 18a, 18b. For example, the cooling channel structure 25 can be formed by wave-shaped elevations or depressions which extend circumferentially around the main axis 100 in the same direction and/or parallel to one another. In the simplest embodiment, the partition wall 12 can be designed to be flat instead of the wave section 15 in order to cover the cooling channel structure 25 in the axial direction with respect to the main axis 100.

6 shows a three-dimensional representation of an electric drive unit 26 for an electric vehicle, with the cooling system 1 as a further embodiment of the invention. The drive unit 26 essentially comprises an electric machine 27, a transmission 28 and power electronics 29. For example, the transmission 28 is designed as a two-stage spur gear, which serves to translate a drive torque provided by the electric machine 27 to at least or exactly one vehicle wheel. The electric machine 27 and the transmission 28 are arranged, for example, in a housing 30, with the power electronics 29 mounted on the outside of the housing 30.

The housing section 7 forms an integral part of the housing 30 and is arranged on the side of the gear 28. For example, the main axis 100 is connected by a drive shaft 31, as in 8th shown, wherein the heat exchanger section 2 is arranged on the outside with respect to the main axis 100 on an axial end face of the housing 30. The heat exchanger section 2 is curved in this embodiment and extends coaxially to the main axis 100 in an angular range of at least or exactly 180 around the main axis 100.

7 shows the heat exchanger section 2 of the drive unit 26 in an exploded view. The housing section 7 has an arcuate recess 32 on its axial front side for forming the cavity 13 or the first coolant chamber 14a, which is circumferentially delimited by the edge region 17. The housing cover 11 and the partition wall 12 each have a geometrically similar shape to the recess 32, so that they completely cover the recess 32 in the axial direction. The housing cover 11 has a further arcuate recess, not shown, on a side facing the housing section 7, for forming the cavity 13 or the second coolant chamber 14b.

The first flow connection 8a and the first return connection 9a, shown dirty, are each designed as a bore opening into the recess 32, which are arranged diametrically opposite one another with respect to the main axis 100. Accordingly, the second flow connection 8b and the second return connection 9b are each designed as a bore opening into the further recess, which are arranged diametrically opposite one another with respect to the main axis 100. The second return connection 9b is arranged congruently with the first flow connection 8a and the second flow connection 8b is arranged congruently with the first return connection 9a, wherein the first flow connection 8a and the first return connection 9a are fluidically separated in the axial direction with respect to the main axis 100 by the partition wall 12 from the second flow connection 8b and the second return connection 9b. For example, the shaft section 15 can be flat in the area of the connections 8a, 8b, 9a, 9b and wave-shaped in the area between the connections 8a, 8b, 9a, 9b.

The sealing section 16 has a plurality of fastening openings 33, through each of which one of the fastening means 18 is guided and is mounted, in particular screwed, into a corresponding fastening means receptacle 34 in the housing section 7. For example, the housing section 7 and the housing cover 11 are designed as a cast part.

8th shows the electric drive unit 26 in a sectional view along the main axis 100. The electric machine 27 and the transmission 28 are accommodated within the housing 30 in a common interior space 35, which is designed, for example, as a wet space. For example, the first cooling circuit 101 can be designed to implement dry sump lubrication, wherein the first coolant is supplied within the housing to several lubrication points of the electric machine 27 and/or the transmission 28. The first coolant can be collected in a coolant sump, not shown, and then fed back to the first cooling circuit 101. The first coolant is passed through the first coolant space 14a, with heat being dissipated by the second coolant circulating through the second coolant space 14b. The electric machine 27 and/or the transmission 28 thus form the heat source 3 to be cooled.

As already described above, the heat exchanger section 2 is arranged at least in sections around the main axis 100 on the axial front side of the housing 2 adjacent to the interior space 35, resulting in a particularly compact integration of the heat exchanger section 2 into the housing 30. The main axis 100 is defined by a drive shaft 31 of the electric machine 27, wherein the drive shaft 31 is driven about the main axis 100 during operation. The drive shaft 31 is coupled in a rotationally fixed manner to a transmission input shaft 36, which forms a first gear stage of the transmission 28. The transmission input shaft 36 is rotatably supported at the end via a bearing 37 within the housing 30, in particular the housing section 7.

Reference symbols

1

Cooling system

2

Heat exchanger section

3

Heat source

4

first coolant pump

5

second coolant pump

6

cooler

7

Housing section

8a, b

Flow connections

9a,b

Return connections

10

partition wall

11

Housing cover

12

partition wall

13

cavity

14a,b

Coolant rooms

15

Wave section

16

Sealing section

17

Edge area

18a,b

Cooling channels

19

Wave crests

20

Wave troughs

21

sealant

22

Separation section

23a,b

Flow sections

24

Deflection section

25

Cooling channel structure

26

Drive unit

27

electric machine

28

transmission

29

Power electronics

30

Housing

31

drive shaft

32

deepening

33

Mounting opening

34

Fastener holder

35

inner space

36

Gearbox input shaft

37

Camp

100

Main axis

101

first cooling circuit

102

second cooling circuit

A

Distance

H

Wave height

S1

first flow path

S2

second flow path

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 102019212118 A1 [0003]
• DE 102020214829 A1 [0004]

Claims (15)

Cooling system (1) for an electric drive unit (26), with a first and a second cooling circuit (101, 102) for dissipating heat energy from at least one heat source (3) of the electric drive unit (26), with a housing section (7) for receiving the at least one heat source (3), wherein the housing section (7) and/or the heat source (3) defines a main axis (100), with a heat exchanger section (2) for exchanging heat between the first and the second cooling circuit (101, 102), wherein the heat exchanger section (102) is arranged on an axial end face of the housing section (7) with respect to the main axis (100), characterized in that the heat exchanger section (2) is formed by a partition wall (12) and a housing cover (11) fastened to the housing section (7), wherein the partition wall (12) divides a cavity (13) formed between the housing section (7) and the housing cover (11) into a first and a second coolant space (14a, 14b), wherein the first cooling circuit (101) is fluidly connected to the first coolant chamber (14a) and the second cooling circuit (102) is fluidly connected to the second coolant chamber (14b). Cooling system (1) after Claim 1 , characterized in that the housing section (7) and/or the housing cover (11) has a cooling channel structure (25) within the cavity (13), wherein the partition wall (12) cooperates with the cooling channel structure (25) to form a plurality of cooling channels (18a, 18b). Cooling system (1) after Claim 1 or 2 , characterized in that the partition wall (12) has a shaft section (15), wherein the partition wall (12) is axially supported with the shaft section (15) on the housing section (7) and/or the housing cover (11) to form a plurality of cooling channels (18a, 18b). Cooling system (1) after Claim 3 , characterized in that a wave height (H) of the wave section (15) is less than or equal to an axial extension of the cavity (13), so that the wave section (15) is axially supported within the cavity (13) at least in the region of the wave troughs (20) and/or the wave crests (19). Cooling system (1) after Claim 3 or 4 , characterized in that the shaft portion (15) is axially supported within the cavity (13) at least on the side of the cooling circuit (101, 102) with the lower pressure. Cooling system (1) after Claim 3 characterized in that a wave height (H) of the wave section (15) in the axial direction with respect to the main axis (100) has an excess and/or that the wave section (15) is designed to be elastically deformable at least in sections, so that the wave section (15) is axially supported with a prestress within the cavity (13) at least in the region of the wave troughs (20) and/or the wave crests (19). Cooling system (1) according to one of the Claims 2 until 6 , characterized in that a distance (A) between the individual cooling channels (18a, 18b) is less than or equal to 2 mm. Cooling system (1) according to one of the preceding claims, characterized in that the first and/or the second coolant chamber (14a, 14b) are designed to generate and/or support a turbulent flow. Cooling system (1) according to one of the preceding claims, characterized in that the cavity (13) has a circular or arcuate configuration. Cooling system (1) according to one of the preceding claims, characterized in that the partition wall (12) has a circumferential sealing section (16) for fluid-tight sealing of the cavity (13), wherein the sealing section (16) lies sealingly axially between the housing section (7) and the housing cover (11) in an edge region (17) surrounding the cavity (13). Cooling system (1) after Claim 10 , characterized in that the sealing section (16) is formed as a flat material section which is provided on both sides with a sealing means (21). Cooling system (1) according to one of the preceding claims, characterized in that the partition wall (12) is designed as a deep-drawn component and/or is manufactured from sheet metal. Cooling system (1) according to one of the preceding claims, characterized in that the heat exchanger section (2) has a first flow connection (8a) and a first return connection (9a) for connecting the first coolant space (14a) to the first cooling circuit (101) and has a second flow connection (8b) and a second return connection (9b) for connecting the second coolant space (14b) to the second cooling circuit (102), wherein the first flow connection (8a) and the second return connection (9b) are arranged axially opposite one another with respect to the main axis (100) and the second flow connection (8b) and the first return connection (9a) are arranged axially opposite one another with respect to the main axis (100). Cooling system (1) according to one of the preceding claims, characterized in that a first flow path (S1) of the first cooling circuit (101) within the first coolant space (14a) and/or a second flow path (S2) of the second cooling circuit (102) within the second coolant space (14a) is deflected at least once in the circumferential direction with respect to the main axis (100). Electric drive unit (26) for an electric or hybrid vehicle, with the cooling system (2) according to one of the preceding claims.

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