Power electronics device, method for producing a power electronics device, and power inverter having a power electronics device

Abstract

The invention relates to a power electronics device (1) comprising at least one power electronics module (10) and a cooler, wherein the cooler comprises a heat exchanger (20), the heat exchanger being made of metal and designed to connect to the lower face of at least one power electronics module (10) and the heat exchanger delimiting the cooler interior (30), through which a coolant can flow, from above, and the cooler further comprises a cooler rear wall (40), the cooler rear wall being made of plastic and provided on the lower face of the heat exchanger (20) and the cooler rear wall delimiting the cooler interior (30) from below and being peripherally connected, at the edge (42) thereof, to an edge (22) of the heat exchanger (20). In order to allow a cost-effective production and a simple and cost-effective integration of the cooler into the power electronics device (1), the peripheral connection of the cooler rear wall (40), at the edge (42) thereof, to the edge (22) of the heat exchanger (20) is implemented according to the invention with the aid of snap-action hooks (44, 64, 74), by means of which the cooler rear wall (40) and the heat exchanger (20) are held together. The invention further relates to a method for producing said power electronics device and to a power inverter having said power electronics device.

Description

[0001] 202400780

[0002] 1

[0003] Description

[0004] Power electronics device and method for manufacturing a power electronics device, power inverter with a power electronics device

[0005] The present invention relates to a power electronics device, which may in particular be part of a power inverter for supplying power to an electric machine in a vehicle (e.g., an electric or hybrid vehicle). The invention further relates to a method for manufacturing a power electronics device, as well as a power inverter with a power electronics device.

[0006] A power electronics device of the type of interest here comprises one or more power electronics modules structurally integrated within the device. Each module may, for example, have at least one circuit board and electronic components arranged and electrically contacted on it (e.g., diodes, transistors (e.g., MOSFETs), thyristors, capacitors, etc.). To dissipate the heat generated during operation of the circuit arrangement or its components, the power electronics device further comprises a heat sink through which a coolant (e.g., water, water-glycol mixture, etc.) flows. This heat sink is arranged on one side of the at least one power electronics module, which is hereinafter also referred to as the "underside" of the at least one power electronics module.

[0007] In general, a cooler for a power electronics device can, for example, have one or more metal heat exchangers that are integrated into a cooler housing (also called the cooler back panel) or, together with this housing, define an interior space of the cooler through which coolant can flow.

[0008] Inside the radiator, the coolant flows from (at least) one coolant inlet to (at least) one coolant outlet, absorbing heat from the heat exchanger(s) and carrying it away. The heat exchangers themselves spread and conduct the heat from the usually relatively small heat source areas in the power electronics module into the coolant. Typically, the heat exchangers have internal structures such as cooling fins that increase the surface area exposed to the coolant, thus increasing the 202400780

[0009] 2

[0010] Improve heat transfer to the coolant. The properties of the cooler, such as pressure drop, heat transfer properties, and heat distribution, can be optimized by adjusting the shape, number, and position of such structural elements.

[0011] Basically, there are two types of cooling systems: closed coolers and open coolers.

[0012] In closed coolers, the heat exchanger(s) are bonded to the housing (also called the cooler back panel) by a material connection (e.g., soldered or welded). The cooler back panel is usually made of the same metal as the heat exchanger, as inexpensive and robust joining methods such as brazing or friction welding can be used.

[0013] In open radiators, the heat exchanger(s) and the radiator housing can be made of different materials, and the mechanical connection between the heat exchanger and radiator housing is typically achieved via screw connections. The interior is sealed, for example, using solid gaskets, liquid seals, or adhesives.

[0014] In practice, the following problems arise with closed cooling systems that have a heat exchanger and a metal radiator back panel:

[0015] - High material costs. The cooler housing, which is usually a very large part of the cooler, is made of metal, even though the high thermal conductivity of metal is not needed across the entire area.

[0016] - Difficult implementation of complex structures. More complex cooler housings, e.g., with integrated coolant connections or additional mounting elements for integrating further assemblies, are complex to produce and therefore expensive.

[0017] - High thermal mass. When integrating the power electronics modules with the heat exchanger(s) using a sintering or soldering process, the entire cooling unit must be heated and then cooled again, resulting in high cycle time and energy costs during production.

[0018] - Limited adaptability. If it becomes necessary to adapt the heat exchangers to the power electronics modules or the cooler's rear panel connectors to a specific power electronics design, the entire cooler usually needs to be redesigned. This increases the number of required variants and therefore costs.

[0019] - Limited repairability. The cooler can usually only be replaced as a whole. In most cases, where the power electronics module(s) 202400780

[0020] Since 3 components are soldered or sintered onto the heat exchangers, in case of a defect the entire cooler and all power electronics modules must be replaced.

[0021] - High so-called GWP (greenhouse warming potential, meaning higher CO2 emissions during production). CO2 emissions during the production and processing of metals are comparatively high. Therefore, CO2 taxation also leads to higher product costs.

[0022] - Increased likelihood of common-mode interference. The main source of so-called...

[0023] Common-mode interference consists of rapidly fluctuating electrical potentials, for example, at power semiconductors relative to ground or the heat sink. The magnitude of the interference currents is determined not only by the rate of voltage change but also by the capacitance of parasitic capacitances to ground. A large portion of these parasitic capacitances is due to the design and thermal connection of the power electronics module(s) to the coolant. Systems with closed metal heat sinks require more extensive EMC measures for interference suppression.

[0024] In practice, open coolers present the following problems, regardless of the material chosen for the cooler components:

[0025] - Reliable sealing over the lifetime of the seal. With fixed, i.e., removable, sealing solutions, it is essential to prevent coolant from seeping under the seal. In known designs, this is achieved with screw connections positioned around the entire circumference of the seal. The longitudinal screw forces must be high enough to ensure sufficient sealing contact even with aged seals and high coolant pressures.

[0026] - Machining of the sealing surfaces. The groove depths and their surfaces for the seals must be manufactured very precisely.

[0027] - Additional space required due to the screw connections. These connections not only require additional space, for example for screw holes on the heat exchanger and mating threads on the radiator housing, but also necessitate later access to the screws for the tightening tool during production. This accessibility of the tightening tool, in particular, leads to increased space requirements, design limitations, and therefore higher costs.

[0028] Open coolers with metal heat exchangers and cooler housings present additional problems already mentioned for closed coolers, such as high material costs, difficulty in implementing complex structures, high GWP, and increased susceptibility to common-mode interference. 202400780

[0029] 4

[0030] The following problems typically arise with open coolers, which are also known from the prior art, featuring a metal heat exchanger and a plastic cooler housing:

[0031] - Additional space required for mating threads: Due to the lower hardness and higher creep properties of plastic (compared to metal), additional metal mating thread sleeves are usually injection-molded into the plastic. Alternative solutions such as a higher number of screws, more material in the mating thread area, or special screws are also used, but these increase the size and cost of the design.

[0032] In light of the problems described above, it is an object of the present invention to provide a power electronics device with a cooler of the type described above, which can be manufactured cost-effectively and integrated into a power inverter in a simple, cost-effective and advantageous manner.

[0033] According to a first aspect of the invention, this problem is solved by a power electronics device with a cooler according to claim 1. The dependent claims relate to advantageous embodiments and further developments of the invention.

[0034] The power electronics device according to the invention comprises a cooler and at least one power electronics module (which, for example, has a circuit carrier plate and electronic components arranged thereon), wherein the cooler comprises: a heat exchanger made of metal (e.g., aluminum or copper) and provided for connection to a bottom side of at least one power electronics module, which defines the upper boundary of an interior space of the cooler through which a coolant can flow, and a cooler back wall made of plastic (e.g., polyamide) and arranged on the underside of the heat exchanger, which defines the lower boundary of the interior space of the cooler and is connected at its edge around a continuous edge of the heat exchanger, 202400780

[0035] 5 wherein the circumferential connection of the radiator rear wall at its edge to the edge of the heat exchanger is realized by means of snap hooks, by means of which the radiator rear wall and the heat exchanger are held together.

[0036] The terms "bottom" and "top," as well as analogous terms such as "top" and "bottom," "overlapping" and "underlapping," etc., serve only to simplify the description of geometric directions or mutual positional relationships of components of the cooler or the power electronics unit equipped with it. Such terms therefore do not represent any restriction regarding the orientation of the cooler and the power electronics unit or their components in use (the cooler or the power electronics unit can, for example, be used with its top facing downwards or in any other direction).

[0037] In the context of the invention, the term "snap hook" refers to a fastening element arranged on a component of the cooler (e.g., a molded plastic part, a molded plastic or metal part, a fixed metal part, etc.) that has at least a shaft section and a hook-shaped section adjoining it. In the assembled state of the cooler, a positive fit between the hook-shaped section and another component of the cooler ensures that the cooler's rear wall and the heat exchanger are held together. The hook-shaped section can be deformed (e.g., by bending) and forced into the corresponding position (the aforementioned positive fit) by overcoming an elastic restoring force of the snap hook (e.g., in the area of ​​the shaft-like section), and is held in this position by this elastic restoring force (the snap hook is then "locked"). Depending on the design, the snap hook can be used to create a secure connection between the cooler's rear wall and the heat exchanger.By dimensioning the snap hook, a desired pressing force between the cooler back wall and the heat exchanger can also be achieved using the positive locking mechanism.

[0038] In the operation of a power electronics device according to the invention (e.g., as part of a power inverter) with a cooler, heat generated by the at least one power electronics module can be transferred to the cooler, first to the metallic heat exchanger of the cooler and then further to a coolant flowing through the interior of the cooler. 202400780

[0039] 6

[0040] The invention allows for a significant reduction in costs for the cooler and, consequently, for the power electronics unit. The use of expensive materials such as metal can be largely avoided, and a less expensive plastic material can be used for the cooler's rear panel. The snap-in hooks allow for the advantageous avoidance of screw connections and the associated increased space requirements for both the cooler itself and the overall system (e.g., inverter unit) by ensuring screw accessibility during the production process. Furthermore, eliminating screw connections also reduces production costs during the assembly of the cooler and the power electronics unit. Additionally, production costs can be kept low when, for example, soldering or sintering the power electronics modules to connect them to the heat exchanger (keyword: time and energy expenditure for heating and cooling the cooler unit).A further advantage is the reduction of the GWP by avoiding cooler materials with high CO2 emissions (e.g., metal). Finally, with appropriate cooler design, at least limited repairability of the cooler or the power electronics unit formed with it can be advantageously ensured. The snap hooks provided in the invention allow for connection solutions between the heat exchanger(s) and the cooler housing that require less space than conventional solutions with screw connections (space advantage). By eliminating screws on the cooler unit, space for screwdriving tools no longer needs to be reserved in production. This allows for greater design freedom in the overall system and enables more compact designs (space advantage). In particular, plastic solutions for the cooler housing can also be implemented that do not require injected metal elements (e.g.,threaded sleeves) are unnecessary and can therefore be recycled more easily.

[0041] In one embodiment of the invention, it is provided that the snap hooks are formed on the edge of the cooler's rear wall, preferably integrally with the cooler's rear wall (e.g., molded on), such that in the assembled state the edge of the heat exchanger is gripped by the snap hooks.

[0042] In one variant of this embodiment, the snap hooks formed on the edge of the cooler's rear wall are arranged essentially evenly distributed over the entire circumference of this edge. In particular, the multiple snap hooks can be arranged essentially evenly around the circumference. 202400780

[0043] The snap hooks should be arranged in a distributed manner. In many applications, it is advantageous to have at least 4 or at least 6 snap hooks at the edge of the cooler's rear wall. On the other hand, in many cases, a maximum of 40 or 20 snap hooks is more appropriate.

[0044] In another advantageous embodiment of the aforementioned design, the snap hooks formed on the edge of the cooler's rear wall are arranged only over a portion of the circumference of this edge, and on an opposite portion of the circumference, the edge of the cooler's rear wall is formed with a circumferentially extending recess (e.g., a groove) for positively engaging a portion of the heat exchanger's edge located in this portion of the circumference. In this embodiment as well, the multiple snap hooks can be arranged essentially uniformly over the relevant (first-mentioned) portion of the circumference. In many applications, it is advantageous to provide, for example, at least two or at least three snap hooks. On the other hand, in many cases, this number of snap hooks is expediently limited to, for example, a maximum of 20 or, for example, a maximum of 10.

[0045] In general, but especially in the latter variant, it is advantageous if the radiator's rear wall has a plate-shaped "base section" with a rectangular shape in plan view, to which a "border section" extending orthogonally to the base section is attached around a (correspondingly rectangular) edge of the radiator's rear wall. In this case, for example, one of the two long sides of the rectangle can be designated as the "circumference section" (with snap hooks), and the other long side can be designated as the "opposite circumference section" (with a recess such as a groove). Particularly in this case, the two short sides of the rectangle can advantageously represent circumference sections on which, for example, at least one coolant connection is provided, serving as an inlet or outlet for the coolant during radiator operation.

[0046] In one embodiment of the invention, the cooler further comprises a frame circumferentially enclosing the edges of the cooler's rear wall and the heat exchanger, on which the snap hooks are formed, preferably integrally with the frame (e.g., molded in the case of a plastic frame), such that in the assembled state of the cooler's rear wall and the 202400780

[0047] 8

[0048] The frame of the heat exchanger is continuously supported on an upper side of the edge of the heat exchanger and the edge of the radiator back wall is gripped by the snap hooks (or alternatively, that the frame is continuously supported on an underside of the edge of the radiator back wall and the edge of the heat exchanger is gripped by the snap hooks).

[0049] In this embodiment, the multiple snap hooks can be arranged in a substantially uniform distribution around the circumference of the frame. In many applications, it is advantageous to provide, for example, at least 4 or at least 6 snap hooks. On the other hand, in many cases, it is expedient to limit the number of snap hooks to, for example, a maximum of 40 or a maximum of 20.

[0050] In one embodiment of the invention, the cooler further comprises a clamping part surrounding the edges of the cooler's rear wall and the heat exchanger over a portion of the circumference of these edges, on which the snap hooks are formed, preferably integrally with the clamping part (e.g., molded in the case of a clamping part made of plastic), such that, in the assembled state of the cooler's rear wall and the heat exchanger, the clamping part is supported on an underside of the edge of the cooler's rear wall and the edge of the heat exchanger is gripped by the snap hooks (or alternatively, is supported on an upper side of the edge of the heat exchanger and the edge of the cooler's rear wall is gripped by the snap hooks).

[0051] In particular, the multiple snap hooks can be arranged essentially evenly distributed over the relevant part of the circumference at the edge of the clamping part. In many applications, it is advantageous to provide, for example, at least 2 or at least 3 snap hooks. On the other hand, in many cases, this number of snap hooks is expediently limited to, for example, a maximum of 20 or a maximum of 10.

[0052] In an advantageous further development of the embodiment with a clamping element surrounding the edges of the radiator rear wall and the heat exchanger over a portion of the circumference of these edges, it is provided that on an opposite portion of the circumference, the edge of the radiator rear wall is formed with a circumferentially extending recess (e.g., groove) for positively engaging a portion of the edge of the heat exchanger located in this portion of the circumference. 202400780

[0053] 9

[0054] Particularly in the latter design, it is advantageous if the radiator back panel and the heat exchanger each have a rectangular shape when viewed from above. In this case, for example, one of the two long sides of the rectangle can be designated as the "part of the circumference" (containing the clamping element), and correspondingly, the other long side can be designated as the "opposite part of the circumference," on which the radiator back panel has a recess such as a groove. The two short sides of the rectangle can again advantageously represent parts of the radiator's circumference where coolant connections are provided.

[0055] According to another aspect of the present invention, a power inverter is described which comprises the following component:

[0056] - (at least) one previously described power electronics device,

[0057] - (at least) one control circuit which is electrically connected to the (at least one) power electronics module of the (at least one) power electronics device via at least one control signal output.

[0058] Furthermore, there are other interesting uses for a power electronics device of the type described here in a vehicle, for example for one of the following power electronic devices:

[0059] DCDC voltage converters such as HV / LV on-board power converters, HV / HV DCDC converters (e.g. for fuel cell applications), so-called OBC ("On-Board Charger") devices, etc., especially of a vehicle.

[0060] The vehicle may be, for example, a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV).

[0061] In one embodiment of the use, it is provided that during the operation of a power electronics device that is tempered (in particular cooled) by the cooler, a liquid coolant such as water, water-glycol mixture, etc. is allowed to flow through the cooler.

[0062] According to a further aspect of the present invention, a power electronics device is proposed which comprises at least one power electronics module and a 202400780 on a bottom side of the at least one

[0063] 10

[0064] The power electronics module comprises a cooler of the type described here, through which a coolant (such as water) can flow.

[0065] Regarding the specific implementation of the circumferential connection of the radiator rear wall to the heat exchanger (for the purpose of holding together or possibly also pressing together the radiator rear wall and heat exchanger) using snap hooks, in particular reference can be made to all the embodiments and design details described here for the radiator.

[0066] In the context of the invention, the term "power electronics device" means that a comparatively high electrical power is involved for electronic devices, which is generated, controlled, stored, or consumed by the circuit arrangement in question during operation. This is generally the case, for example, when the circuit arrangement is intended for the generation, control, storage, and / or use of electrical energy not solely for data processing, but rather for supplying this energy to "electrical consumers" (such as an electric motor for powering a vehicle). This refers particularly to devices whose power consumption during operation can exceed 100 W, especially 1 kW.Particularly in the case of a power electronics device for implementing an inverter, power semiconductor components, e.g., diodes, transistors (e.g., MOSFETs as controllable switches), etc., may be arranged on the at least one power electronics module. In particular, semiconductor components manufactured using SiC (silicon carbide) technology may be provided.

[0067] According to a further aspect of the present invention, a method for manufacturing a (previously described) power electronics device is proposed, wherein the power electronics device comprises at least one power electronics module, e.g. with a circuit carrier plate and electronic components arranged thereon, and a cooler through which a coolant can flow, which is arranged on a bottom side of the at least one power electronics module.

[0068] The method according to the invention comprises the following steps: 202400780

[0069] 11

[0070] Attaching (e.g. soldering, sintering, etc.) at least one power electronics module to the top side of a metal heat exchanger,

[0071] Attaching a plastic radiator back panel at its edge continuously to an edge of the heat exchanger on the underside of the heat exchanger, in order to form a radiator with the heat exchanger and the radiator back panel, arranged on the underside of the at least one power electronics module and through which a coolant can flow, such that the heat exchanger defines an interior space of the radiator through which the coolant can flow on its upper side and the radiator back panel defines this interior space on its lower side, wherein the continuous attachment of the radiator back panel at its edge to the edge of the heat exchanger is accomplished by means of a locking mechanism of snap hooks, by means of which the radiator back panel and the heat exchanger are held together in the mounted power electronics device.

[0072] In the power electronics device and in the method for assembling a power electronics device, the power electronics module(s) used can each comprise, for example, (at least) a circuit board and electronic components arranged on this circuit board. Advantageously, the components can be arranged, for example, on the top side of the circuit board, while a bottom side of the circuit board serves as a connection surface for the mechanical and thermal attachment of the module to the top side of the heat exchanger.

[0073] The circuit carrier board (or at least one of several circuit carrier boards of the module) can, for example, have an electrically insulating substrate (e.g., made of a ceramic material) on the upper side of which a conductor arrangement (e.g., made of copper) for electrical conduction and, in particular, electrical contacting of the components, and on the underside of which a metallic layer (e.g., made of copper) for connecting the power electronics module to the heat sink, e.g., via a solder layer or a sintered layer. For electrical contacting of the components, these can be connected, for example, via respective solder layers or sintered layers and / or so-called bond wires to a conductor of the conductor arrangement and / or to so-called 202400780

[0074] 12

[0075] be connected to contact elements (e.g., bent stamped parts made of copper material).

[0076] The invention is further described below with reference to exemplary embodiments and the accompanying drawings. These depict:

[0077] Fig. 1 shows a top view of a cooler rear wall with a seal for a cooler of a power electronics device according to a first embodiment.

[0078] Fig. 2 shows a top view of a heat exchanger with power electronics modules attached to its upper side for the cooler of the power electronics unit according to the first embodiment.

[0079] Fig. 3 shows a top view of the power electronics unit with the cooler according to the first embodiment, which was produced by joining together the assemblies shown in Figs. 1 and 2.

[0080] Fig. 4 shows a sectional view of the power electronics unit from Fig. 3.

[0081] Fig. 5 shows a top view of a cooler rear wall with a seal for a cooler of a power electronics device according to a second embodiment.

[0082] Fig. 6 shows a top view of a heat exchanger with power electronics modules attached to its upper side for the cooler of the power electronics unit according to the second embodiment.

[0083] Fig. 7 shows a top view of a frame for the cooler of the power electronics unit according to the second embodiment,

[0084] Fig. 8 shows a top view of the power electronics unit with the cooler according to the second embodiment, which is formed by joining together the components shown in the Fig.

[0085] The components shown in 5, 6 and 7 were manufactured.

[0086] Fig. 9 shows a sectional view of the power electronics unit from Fig. 8.

[0087] Fig. 10 shows a top view of a cooler rear wall with a seal and a clamping part for a cooler of a power electronics device according to a third embodiment, 202400780

[0088] 13

[0089] Fig. 11 shows a top view of a heat exchanger with power electronics modules attached to its upper side for the cooler of the power electronics unit according to the third embodiment.

[0090] Fig. 12 shows a top view of the power electronics unit with the cooler according to the third embodiment, which was produced by a combination of the assemblies shown in Figs. 10 and 11.

[0091] Fig. 13 shows a sectional view of the power electronics unit from Fig. 12, and

[0092] Figs. 14 to 16 are sectional views of the assemblies shown in Figs. 10 and 11 at various stages of a method for assembling the power electronics device shown in Figs. 12 and 13.

[0093] Figures 1 to 4 illustrate a first embodiment of a cooler and a power electronics unit 1 equipped with it.

[0094] Fig. 1 shows an embodiment of a cooler rear wall 40 made of plastic as a component for the manufacture of the cooler according to this first embodiment (see Fig. 3 and 4).

[0095] In the example shown in Fig. 1, the cooler rear wall 40 has a rectangular format in plan view, wherein a flat "bottom section" extending in the drawing plane of Fig. 1 is formed in a central rectangular area of ​​the cooler rear wall 40, to which a "border section" is attached around an edge 42 of the cooler rear wall 40, extending orthogonally to the bottom section (out of the drawing plane of Fig. 1).

[0096] Coolant connections 46 and 48 are formed on opposite parts of the circumference of the radiator rear wall 40 (in Fig. 1 top and bottom) on the edge section of the radiator rear wall 40, which serve as a coolant inlet and a coolant outlet during operation of the radiator.

[0097] The bottom section, the edge section, and the coolant connections are preferably manufactured in one piece (e.g., by injection molding). 202400780

[0098] 14

[0099] Furthermore, in the illustrated example, a circumferential seal 50 is provided on the edge section of the cooler's rear wall 40 in order to achieve a coolant-tight circumferential connection of the edge of a heat exchanger at this point on the edge 42 of the cooler's rear wall 40. The seal 50 can be designed, for example, as a fixed insert seal (for a detachable connection, e.g., inserted into a circumferential groove) or, for example, as a liquid seal (e.g., bonding, for a permanent or conditionally detachable connection).

[0100] Finally, in the illustrated example, several snap hooks 44 are formed on the edge section of the cooler's rear wall 40, by means of which the circumferential connection of the cooler's rear wall 40 (Fig. 1) at its edge 42 to the edge 22 of the heat exchanger 20 is realized. In this example, the snap hooks 44 on the edge 42 of the cooler's rear wall 40 are integrally formed on the edge section, projecting upwards, and are arranged substantially around the entire circumference of the edge 42.

[0101] Fig. 2 shows an embodiment of a metal heat exchanger 20 for the manufacture of the cooler according to the first embodiment (see Figs. 3 and 4).

[0102] In the example shown in Fig. 2, the heat exchanger 20, adapted to the shape of the cooler housing (cooler rear wall 40 of Fig. 1), has a rectangular shape in plan view. In an upper area of ​​the heat exchanger 20 (lying in the plane of Fig. 1), a flat "plate section" is formed, from which several cooling fins project downwards in a central area of ​​the heat exchanger 20, extending orthogonally to the plate section (into the plane of Fig. 1). These cooling fins are clearly visible in the sectional view of Fig. 4 and are preferably formed integrally with the plate section.

[0103] In order to manufacture (assemble) a complete power electronics unit (Figs. 3 and 4) simultaneously with a single manufacturing (assembly) process of the cooler, one or more power electronics modules 10 can already be connected to the top of the heat exchanger, as shown in Fig. 2, even before the cooler is formed by joining the heat exchanger and the cooler's rear wall. 202400780

[0104] 15

[0105] In the example shown in Fig. 2, three power electronics modules 10 are arranged on the top surface of the heat exchanger 20. Each module (not shown in the figure) has a circuit carrier plate extending parallel to the plate section of the heat exchanger 20 and electrically contacted electronic components arranged on the top surface of this circuit carrier plate. The undersides of the respective circuit carrier plates can be connected to the top surface of the heat exchanger 20, for example, via a solder layer, sintered layer, or (thermally conductive) adhesive layer. In particular, a thermal interface material (TIM) can also be provided between the underside of the power electronics modules 10 and the top surface of the heat exchanger 20.

[0106] The three power electronics modules 10 could, for example, each be a so-called "phase module" of a three-phase inverter formed from three such modules 10, which serves to provide one of the three phase currents with which, for example, a three-phase AC electric motor is powered. In an inverter with a different number of required phase currents, a correspondingly different number of modules 10 could, for example, be provided on the top of the heat exchanger 20. Also deviating from the example shown, an inverter could also be implemented with several (e.g., 2 or 3) modules 10 per phase current.

[0107] To match the shape of the cooler back panel 40 in Fig. 1, the heat exchanger 20, as already mentioned, has a plate-shaped section (plate section) on its upper side with a rectangular format in plan view, so that the circumferential connection of the cooler back panel 40 to the heat exchanger 20 can be achieved by a locking action of the snap hooks 44. As a result of this locking action of the snap hooks 44, the cooler back panel 40 and the heat exchanger 20 are held together in the finished cooler (see Figs. 3 and 4).

[0108] Particularly advantageous are the snap hooks 44 having respective "lead-on chamfers" on their upper sides (visible in Fig. 4), so that the aforementioned corrosion of the snap hooks 44 (to create a positive locking connection of the hooks on the upper side of the heat exchanger 20) can be accomplished in a simple manner by pressing the heat exchanger 20 onto the cooler rear wall 40.

[0109] Figures 3 and 4 show, in top view (Fig. 3) and sectional view (Fig. 4), a power electronics device 1 with a cooler according to the first 202400780

[0110] 16

[0111] Exemplary embodiment, as produced by joining (pressing together) the assemblies shown in Figs. 1 and 2, and thereby locking the snap hooks 44.

[0112] The power electronics unit 1 comprises the three power electronics modules 10 and the cooler, which is arranged on the underside of the power electronics modules 10. In this example, the cooler includes the heat exchanger 20 connected to the underside of the power electronics modules 10, the seal 50, and the cooler backplate 40 located on the underside of the heat exchanger 20. An interior space 30 of the cooler, through which a coolant flows, is bounded on the upper side by the heat exchanger 20 (or its cooling fins) and on the lower side by the cooler backplate 40. In the illustrated example, the cooling fins extend vertically to the bottom section of the cooler backplate 40, so that corresponding flow passages are formed between adjacent cooling fins in the interior space 30.

[0113] As can be seen in Fig. 4, the edge 22 of the heat exchanger 20 is gripped by the snap hooks 44 (overlaps), so that the radiator back wall 40 and the heat exchanger 20 are held together.

[0114] In summary, the first embodiment according to Figures 3 and 4 represents an open radiator with a metal heat exchanger 20 and a plastic radiator housing (radiator back panel 40). This embodiment features a solution variant with a one-piece radiator back panel and integrated, circumferential snap hooks 44 (also made of plastic). Sealing is achieved via a gasket 50 between the radiator back panel and the heat exchanger, which can advantageously be, for example, a flexible wet gasket (e.g., adhesive). The advantage of a flexible wet gasket is that it does not require contact pressure, so the snap hooks 44 only need to be designed to withstand the holding forces generated during operation by the maximum coolant pressure in the radiator's interior 30. The snap hooks then ensure only the mechanical integrity of the assembly.The number, design and position of the snap hooks can be selected so that they can withstand the maximum mechanical pressure expected in the usage situation (typically e.g. about 3-5 bar).

[0115] In the following description of further embodiments, the same reference numerals are used for components with the same effect. 202400780

[0116] Section 17 essentially only addresses the differences to the embodiment(s) already described and expressly refers to the description of previous embodiments.

[0117] Figures 5 to 9 illustrate a second embodiment of a cooler and a power electronics unit 1 equipped with it.

[0118] Fig. 5 shows an embodiment of a cooler rear wall 40 as a component for manufacturing the cooler according to this second embodiment (see Figs. 8 and 9).

[0119] The radiator rear wall 40 of Fig. 5 differs from the radiator rear wall 40 of Fig. 1 in that no snap hooks (44 in Fig. 1) are formed on the edge section of the radiator rear wall 40 located at an edge 42.

[0120] As can be seen in Fig. 5, a circumferential seal 50 is provided again on the edge section of the cooler rear wall 40.

[0121] Fig. 6 shows an embodiment of a heat exchanger 20 for manufacturing the cooler according to the second embodiment (see Figs. 8 and 9). This heat exchanger 20 is identical to the heat exchanger 20 of Fig. 2 and is again provided with several power electronics modules 10 on its upper surface.

[0122] Fig. 7 shows an embodiment of a frame 60 as a further component for the manufacture of the cooler according to the second embodiment (see Fig. 8 and 9).

[0123] The frame 60, adapted to the shape of the cooler rear wall 40 and the heat exchanger 20, has a closed rectangular profile in plan view, with a flat 'support section' extending in the plane of Fig. 7 (for subsequent support on the upper surface of the edge 22 of the heat exchanger 20) formed, to which a 'edge section' is attached around an edge 62 of the frame 60, extending orthogonally to the support section (into the plane of Fig. 7). 202400780

[0124] 18

[0125] Snap hooks 64 are formed on this edge section of the frame 60, or representing this edge section, by means of which the circumferential connection of the cooler rear wall 40 at its edge 42 to the edge 22 of the heat exchanger 20 is realized. The snap hooks 64 are provided projecting downwards from the frame 60 and are arranged substantially around the entire circumference of the edge 62.

[0126] The snap hooks 64 can, for example, be formed integrally with the support section of the frame 60. If the frame 60 is made of plastic (e.g., by injection molding), the snap hooks 64 can advantageously be, for example, integrally molded onto the edge section.

[0127] Figures 8 and 9 show, in top view (Figure 8) and sectional view (Figure 9), a power electronics device 1 with a cooler according to the second embodiment, as produced by joining the assemblies (40, 50 and 20, 10) shown in Figures 5 and 6 and subsequently fixing the latter assemblies (40, 50, 20, 10) to one another by placing the frame 60 shown in Figure 7 on top, thereby engaging the snap hooks 64. In this example, the frame 60 functions, in a sense, as a "mounting tube" for holding or pressing together the components 20 and 40.

[0128] As can be seen in the views of Figs. 8 and 9, the frame 60 encloses the edges 42, 22 of the radiator rear wall 40 and the heat exchanger 20 in the circumferential direction (see top view of Fig. 8), wherein the frame 60 is supported on one side (visible in Fig. 9 above) on an upper side of the edge 22 of the heat exchanger 20 and on the other side (visible in Fig. 9 below) the edge 42 of the radiator rear wall 40 is gripped (engaged from below) by the snap hooks 64.

[0129] In this second embodiment, the rear wall of the cooler 40 is also connected around its edge 42 to the edge 22 of the heat exchanger 20 by means of snap hooks 64, by means of which the rear wall of the cooler 40 and the heat exchanger 20 of the cooler are held together.

[0130] Particularly advantageous are the chamfers on their undersides (visible in Fig. 9), which allow for easy removal of rust from the snap hooks 64 (for creating the positive locking connection on the underside of the cooler rear wall 40). 202400780

[0131] 19

[0132] The power electronics assembly 1 of Figures 8 and 9 comprises the three power electronics modules 10 and the cooler, which is arranged on the underside of the power electronics modules 10. The cooler includes the heat exchanger 20 connected to the underside of the power electronics modules 10, the seal 50, the cooler back panel 40 arranged on the underside of the heat exchanger 20, and the frame 60 with the snap hooks 64. As can be seen in Figure 9, in this example the edge 42 of the cooler back panel 40 is gripped (engaged from below) by the snap hooks 64, so that the cooler back panel 40, the heat exchanger 20, and the frame 60 are held together.

[0133] In summary, the second embodiment according to Figures 8 and 9 represents an open cooler with a two-part cooler housing, namely the cooler rear wall 40 made of plastic and a mounting frame (frame 60) with integrated, circumferential snap hooks 64. The two-part design offers the advantage that the material properties of both housing elements 40 and 60 can be selected separately and optimized according to their mechanical and thermal requirements. Therefore, the components 40 and 60 can, for example, be made of different materials. A wet gasket or, as shown in the figures, a solid-fill gasket 50 can be used as a seal between the heat exchanger 20 and the cooler rear wall 40. The mounting frame (frame 60) is preferably made of plastic. However, it can also be made of metal, for example, if particularly high contact forces are required on the seal.

[0134] Figures 10 to 13 illustrate a third embodiment of a cooler and a power electronics unit 1 equipped with it.

[0135] Fig. 10 shows an embodiment of a cooler rear wall 40 made of plastic and a clamping part 70 arranged thereon as an assembly for the manufacture of the cooler according to the third embodiment (see Figs. 12 and 13).

[0136] The cooler rear wall 40 of Fig. 10, like the embodiments already described above according to Figs. 1 and 5, has a rectangular format in plan view, wherein a flat "bottom section" extending in the plane of Fig. 10 is formed in a central rectangular area of ​​the cooler rear wall 40, on which a continuous 202400780 is formed at an edge 42 of the cooler rear wall 40.

[0137] 20

[0138] "Border section" adjoins, extending orthogonally to the bottom section (out of the drawing plane of Fig. 10).

[0139] The cooler rear wall 40 of Fig. 10 differs, for example, from the embodiment according to Fig. 5 in that, on a portion of the circumference of the edge 42 of the cooler rear wall 40, the edge section of the cooler rear wall 40 has an increased height and is formed in this area with a circumferentially extending groove-like recess. This portion of the circumference with increased height, and thus also the aforementioned recess, extends in the example of Fig. 10 over the right-hand "long rectangular side" of the rectangular cooler rear wall 40. The recess serves to subsequently secure a portion of the edge of the respective heat exchanger located in this part of the circumference.

[0140] As can be seen in Fig. 10, a seal 50, e.g., an insert seal, is provided around the entire rectangular circumference of the edge section of the cooler's rear wall 40 to ensure a coolant-tight, circumferential connection between the edge 42 of the cooler's rear wall 40 and an edge of the heat exchanger. In the example shown in Fig. 10, the seal 50 extends partially within the recess, specifically over the portion of the circumference occupied by the recess, i.e., the right-hand "long rectangular side" of the circumference in Fig. 10 (see also Fig. 13). The bottom section and the edge section of the cooler's rear wall 40, as well as the coolant connections 46 and 48, which are located on the edge section at the "short rectangular sides," are preferably manufactured in one piece (e.g., by injection molding).

[0141] The assembly shown in Fig. 10 further comprises, as mentioned above, the clamping part 70, which is dimensioned and arranged on the cooler rear wall 40 such that it surrounds the edge 42 of the cooler rear wall 40 over that part of the circumference of this edge 42 (left in Fig. 10) which is opposite the part of the circumference of the edge 42 already mentioned above (right in Fig. 10) where the increased height of the edge section and the recess are provided.

[0142] Snap hooks 74 are formed on the clamping part 70, which facilitate the continuous connection of the cooler's rear wall 40 at its edge 42 to the edge 22 of the heat exchanger. In the illustrated example, the snap hooks 74 are oriented upwards on the clamping part 70 and extend over the entire (in 202400780

[0143] 21

[0144] Fig. 10 (vertical length of the clamp part 70) arranged evenly distributed.

[0145] The snap hooks 74 are preferably formed integrally with the other sections of the clamping part 70. If the clamping part is made of plastic, the snap hooks can, for example, be integrally formed on a longitudinal "web section" of the clamping part, which connects the bases (shaft sections) of the snap hooks. Preferably, and in this example, the clamping part 70 is made of metal (e.g., as a stamped and bent part from a sheet of metal), and the snap hooks 74 can advantageously also be integrally formed with the aforementioned "web section".

[0146] Fig. 11 shows an embodiment of a metal heat exchanger 20 for the manufacture of the cooler according to the third embodiment (see Figs. 12 and 13).

[0147] This heat exchanger 20 is identical to the heat exchangers 20 shown in Figures 2 and 6 and is again provided on its upper surface with several (in this example: three) power electronics modules 10, in order to form the complete power electronics unit (Figures 12 and 13) simultaneously with the manufacturing process of the cooler. The design and connection of the power electronics modules on the upper surface of the heat exchanger 20 can be provided, for example, as already described above for the other embodiments.

[0148] Figures 12 and 13 show in top view (Fig. 12) and sectional view (Fig. 13) a power electronics device 1 with a cooler according to the third embodiment, as produced by joining the assemblies shown in Figures 10 and 11, and thereby locking the snap hooks 74.

[0149] The power electronics unit 1 thus comprises the three power electronics modules 10 and the cooler, which is arranged on the underside of the power electronics modules 10. The cooler includes the heat exchanger 20, the seal 50, the cooler back panel 40, and the clamping element 70. An interior space 30 of the cooler, through which a coolant can flow, is again bounded on the upper side by the heat exchanger 20 and on the lower side by the cooler back panel 40. 202400780

[0150] 22

[0151] As can be seen in Fig. 13, the edge 22 of the heat exchanger 20 is gripped by the snap hooks 74 (overlaps), so that the radiator back wall 40 and the heat exchanger 20 are held together. On the other hand, the clamping part 70 is supported on the underside of the edge 42 against the radiator back wall 40.

[0152] Thus, the clamping part 70 acts in the relevant part of the circumference of the cooler, in the example along the left "long rectangular side" of the cooler format in Figs. 10 and 12, as a clamp which holds the cooler rear wall 40 and the heat exchanger 20 together.

[0153] In the opposite part of the circumference (in Figs. 10 and 12 on the right) the edge 22 of the heat exchanger 20 is caught and fixed in the aforementioned groove-like recess on the edge section of the cooler's rear wall 40.

[0154] In the completed power electronics device 1 according to Figures 12 and 13, a clamping element 70 is provided surrounding the edges 42, 22 of the cooler back wall 40 and the heat exchanger 20 via a (left in the figures) part of the circumference of these edges 42, 22, on which the snap hooks 74 are integrally formed, wherein, in the assembled state of the cooler back wall 40 and the heat exchanger 20, the clamping element 70, in the illustrated example, is supported on an underside of the edge 42 of the cooler back wall 40 and the edge 22 of the heat exchanger 20 is engaged (overlapped) by the snap hooks 74, and wherein, on the opposite part of the circumference, the edge 42 of the cooler back wall 40 is formed with the circumferentially extending recess in order to positively engage the part of the edge 22 of the heat exchanger 20 located in this (right in the figures) part of the circumference. A wet seal is preferably used here as seal 50.

[0155] In summary, the third embodiment according to Figures 12 and 13 represents an open, assembled cooler with snap hooks 74 on only one side of the cooler when viewed from above. The cooler housing is at least partially (cooler rear wall 40) made of plastic and has, on the side opposite the snap hooks 74, a retaining element integrated into the cooler housing (in the edge section of the cooler rear wall) in the form of the aforementioned recess or groove, which serves to receive and fix the corresponding edge area of ​​the heat exchanger 20. 202400780

[0156] 23

[0157] The clamping part 70 with the snap hooks 74 can advantageously be made of metal, for example, and fixed to the cooler back wall (as can be seen in Figs. 13 and 16 at the bottom left), for example, to advantageously provide a pre-assembled module for mounting the power electronics device 1.

[0158] In all the embodiments described above, the respective multiple power electronics modules 10 can, for example, form an inverter.

[0159] In particular, the power electronics device 1 can thus be, for example, a multi-phase (e.g., three-phase) inverter in which (at least) one power electronics module is provided for each individual phase current. Such a "phase module" can, in a manner known per se, for example, comprise a half-bridge circuit in the form of a series connection of two controllable switches (e.g., transistors, especially MOSFETs).

[0160] Figures 14 to 16 illustrate a method for assembling the power electronics device 1 shown in Figures 12 and 13.

[0161] In one process step, at least one power electronics module 10 is attached to the top side of a metal heat exchanger 20 (e.g., by soldering). In a further process step, a plastic cooler backplate 40 is attached at its edge 42 to a continuous edge 22 of the heat exchanger 20 on the underside of the heat exchanger 20, in order to form a cooler with the heat exchanger 20 and the cooler backplate 40, arranged on the underside of the at least one power electronics module 10 and through which a coolant can flow, such that the heat exchanger 20 defines an interior space 30 of the cooler through which the coolant can flow on its upper side and the cooler backplate 40 defines this interior space on its lower side.

[0162] Figures 14 to 16 show various stages of this further process step, i.e. the integration of heat exchanger 20 including power electronics module(s) 10 with the cooler housing comprising the cooler rear wall 40 with the (rusted) clamp part 70 with the snap hooks 74 attached to it.

[0163] As shown in Fig. 14, the heat exchanger 20 is first inserted into the housing side (right side in Figs. 14 to 16) with the recess on the inside of the edge section of the cooler's rear wall 40. 202400780

[0164] 24

[0165] As shown in Fig. 15, the heat exchanger 20 is then pressed onto the housing under the snap hooks 74 on the opposite (left in Figs. 14 to 16) side (see arrows in Figs. 14 and 15).

[0166] Finally, Fig. 16 shows the assembled state, in which the circumferential connection of the cooler's rear wall 40 at its edge 42 to the edge 22 of the heat exchanger 20 is achieved by means of a locking action of the snap hooks 74. The cooler's rear wall 40 and the heat exchanger 20 are thus held together in the illustrated assembled power electronics unit 1 by means of the snap hooks 74. The snap hooks 74 again have respective 'lead-on chamfers' so that the corrosion of the snap hooks 74 can be easily remedied by pivoting the heat exchanger 20 towards the cooler's rear wall 40. Particularly advantageously, in this example, the snap hooks 74 each have an easily manageable tab-like section (which in this example also forms the lead-on chamfers) on which the snap hooks 74 can later be gripped, for example for the purpose of disassembly, and thus advantageously released from the positive engagement.

[0167] In summary, the invention and the described embodiments provide a cooler for a power electronics device comprising at least one power electronics module. The cooler includes a metal heat exchanger designed for attachment to the underside of at least one power electronics module, which defines the upper boundary of the cooler's interior space through which a coolant flows. The cooler also includes a plastic rear wall located on the underside of the heat exchanger, which defines the lower boundary of the cooler's interior space and is connected around its perimeter to an edge (22) of the heat exchanger. The perimeter connection of the rear wall to the edge of the heat exchanger is achieved by means of snap hooks, which hold the rear wall and the heat exchanger together. 202400780

[0168] 25

[0169] Reference symbol list

[0170] 1 Power electronics unit

[0171] 10 Power electronics module

[0172] 20 heat exchangers

[0173] 22 Edge of the heat exchanger

[0174] 30 Interior

[0175] 40 Radiator back panel

[0176] 42 Edge of the radiator rear wall

[0177] 44 snap hooks

[0178] 46 Coolant connection

[0179] 48 Coolant connection

[0180] 50 Seal

[0181] 60 frames

[0182] 62 Edge of the frame

[0183] 64 snap hooks

[0184] 70 clamp part

[0185] 72 Edge of the bracket part

[0186] 74 snap hooks

Claims

202400780 26 Patent claims 1. Power electronics device (1) comprising a cooler and at least one power electronics module (10), wherein the cooler comprises: a heat exchanger (20) made of metal and provided for connection to a bottom surface of the at least one power electronics module (10), which defines an interior space (30) of the cooler through which a coolant can flow, and a cooler back wall (40) made of plastic and arranged on the bottom surface of the heat exchanger (20), which defines the interior space (30) of the cooler on the underside and is connected at its edge (42) circumferentially to an edge (22) of the heat exchanger (20), characterized in that the circumferential connection of the cooler back wall (40) at its edge (42) to the edge (22) of the heat exchanger (20) is realized by means of snap hooks (44, 64, 74) by means of which the cooler back wall (40) and the heat exchanger (20) are held together.

2. Power electronic device (1) according to claim 1, wherein the snap hooks (44) are formed on the edge (42) of the cooler rear wall (40) and integrally with the same (40), such that in the held-together state the edge (22) of the heat exchanger (20) is gripped by the snap hooks (44).

3. Power electronic device (1 ) according to claim 2, wherein the snap hooks (44) formed on the edge (42) of the cooler rear wall (40) are arranged substantially distributed over the entire circumference of this edge (42).

4. Power electronic device (1) according to claim 2, wherein the snap hooks (44) formed on the edge (42) of the cooler rear wall (40) are arranged distributed over a part of the circumference of this edge (42), and wherein on an opposite part of the circumference the edge (42) of the cooler rear wall (40) is formed with a circumferentially extending recess for positively locking a part of the edge (22) of the heat exchanger (20) located in this part of the circumference. 202400780 27 5. Power electronics device (1) according to one of the preceding claims, further comprising: a frame (60) circumferentially enclosing the edges (42, 22) of the cooler rear wall (40) and the heat exchanger (20), on which the snap hooks (64) are integrally formed with the same (60), such that in the assembled state of the cooler rear wall (40) and the heat exchanger (20) the frame (60) is continuously supported on an upper surface of the edge (22) of the heat exchanger (20) and the edge (42) of the cooler rear wall (40) is gripped by the snap hooks (64).

6. Power electronics device (1) according to one of the preceding claims, further comprising: a clamping part (70) surrounding the edges (42, 22) of the cooler back wall (40) and the heat exchanger (20) over a part of the circumference of these edges (42, 22), on which the snap hooks (74) are formed integrally with the same (70), such that in the assembled state of the cooler back wall (40) and the heat exchanger (20) the clamping part (70) is supported on an underside of the edge (42) of the cooler back wall (40) and the edge (22) of the heat exchanger (20) is gripped by the snap hooks (74), wherein on an opposite part of the circumference the edge (42) of the cooler back wall (40) is formed with a circumferentially extending recess for positively locking a part of the edge (22) of the heat exchanger (20) located in this part of the circumference.

7. Power inverter, featuring: - a power electronics device (1) according to any one of the preceding claims, - a control circuit which is electrically connected to the power electronics module (10) of the power electronics device (1) via at least one control signal output.

8. Method for manufacturing a power electronics device (1) according to any one of the preceding claims, wherein the method comprises the following steps: 202400780 28 Connecting at least one power electronics module (10) to a top surface of a metal heat exchanger (20), Connecting a plastic radiator back panel (40) at its edge (42) around a continuous edge (22) of the heat exchanger (20) on the underside of the heat exchanger (20) to form a radiator arranged on the underside of the at least one power electronics module (10) and through which a coolant can flow, such that the heat exchanger (20) defines an interior space (30) of the radiator through which the coolant can flow on its upper side and the radiator back panel (40) defines this interior space (30) on its lower side, wherein the continuous connection of the radiator back panel (40) at its edge (42) to the edge (22) of the heat exchanger (20) is effected by means of a locking mechanism of snap hooks (44, 64, 74), by means of which the radiator back panel (40) and the heat exchanger (20) are held together in the mounted power electronics unit (1). are.

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