Cooling system for an inverter

Abstract

The present invention relates to a cooling system (1) for an inverter, comprising a housing and a plurality of plates which are stacked together inside the housing, the plates comprising two top plates (8) and at least two plates with cooling structures (6) configured to disrupt the flow of a coolant of the cooling system (1), the top plates (8) comprising a first top plate (8A) stacked on top of a second top plate (8B), the second top plate (8B) being stacked on top of the plates with the cooling structures (6), the second top plate (8B) comprising a marking (24) and the first stop plate (8A) comprising a through hole (28) facing the marking (24).

Description

[0001] DESCRIPTION

[0002] Titled Cooling system for an inverter

[0003] The invention relates to the fields of electronics and electrical engineering, and more particularly to the field of inverters.

[0004] Inverters are power electronics devices capable of generating alternating current from direct current. Inverters can be integrated into motor vehicles, particularly hybrid or electric vehicles, in order to convert direct current supplied by batteries into alternating current to power the electric motor.

[0005] Such inverters typically comprise a power module and a at least one printed circuit boards. Additionally, the inverters may comprise a cooling system through which a coolant fluid flows. The purpose of the cooling system is to cool the various components of the inverter using the coolant fluid. To this end, the cooling system usually comprises a plurality of plates which are stacked together, with the coolant fluid flowing between the plates in a dedicated cooling structure.

[0006] As traceability is becoming more and more important nowadays, motor vehicle constructors looking to buy inverters require them to include a specific label with tracing information. Such tracing information may include the production date of the inverter and the production plant it has been manufactured in. The specific label comprising this tracing information is usually placed on a top surface of the plates, as it is the only accessible and visible surface once the cooling system has been assembled on the inverter.

[0007] However, the top surface of the plates requires machining to ensure a good flatness of the inverter. Such machining causes traceability issues as it erases the label with tracing information.

[0008] The present invention fits into this context by providing a cooling system for an inverter comprising a label with tracing information which is easily visible.

[0009] In this context, the present invention is directed to a cooling system for an inverter, comprising a housing and a plurality of plates which are stacked together inside the housing, the plates comprising two top plates and at least two plates with cooling structures configured to disrupt the flow of a coolant of the cooling system, the top plates comprising a first top plate stacked on top of a second top plate, the second top plate being stacked on top of the plates with the cooling structures, the second top plate comprising a marking and the first stop plate comprising a through hole facing the marking.

[0010] The cooling system for an inverter according to the invention is destined to equip a motor vehicle, for instance a hybrid or electric vehicle. It is configured for the circulation of a coolant fluid, the purpose of this coolant fluid being the cooling of the inverter.

[0011] The cooling system comprises multiple plates, among which plates with cooling structures through which the coolant fluid flows and two top plates covering the stack of plates with cooling structures.

[0012] The cooling structures are for example meander-like cooling structures.

[0013] The two top plates may be smooth plates without cooling structures. Alternatively, one of the top plates may comprise cooling structures. The top plates are placed on top of the plates with cooling structures. In other words, the two plates are superimposed on the plates with the cooling structures. The two plates more particularly comprise a first top plate and a second top plate, the second top plate being stacked over the plates with the cooling structures and under the first top plate.

[0014] The first top plate requires a machining operation in order to flatten it, for instance to receive other components of the inverter such as a power module. The second top plate comprises a marking, for instance an engraving or a label. The marking is more precisely a traceability marking such as a data matrix code (DMC) comprising information about the manufacturing of the inverter. In some embodiments, the second top plate comprises cooling structures on its face which is opposite to the marking.

[0015] The first top plate comprises an opening, here a through hole, facing the marking. The opening permits to see the marking when the cooling circuit is seen from the top.

[0016] A through hole can be entirely surrounded with material of the first top plate. The outline of the through hole is continuous.

[0017] The through hole may also be formed thanks to a cut in the first top plate, giving access to the second top plate. In this case, the through hole is only partially surrounded with material of the first top plate.

[0018] This through hole allows an operator of the cooling system to see the marking on the second top plate. As a result, when the top surface of the cooling system, i.e. its first top plate, is machined to flatten it as is required, the second top plate is untouched and the marking it bears stays intact.

[0019] The first top plate thus has both a protection role and a visibility role for the marking on the second top plate.

[0020] According to an optional characteristic of the invention, the second top plate comprises a first face facing one of the plates with the cooling structures and a second face facing the first top plate, the marking being on the second face. The first face and the second face of the second top plate are opposed according to a stacking direction of the plates. The traceability marking is positioned on the face which is in contact with the first top plate so that is it visible through the through hole. The first face may have cooling structures. According to an optional characteristic of the invention, the first top plate and the second top plate are of different heights, such heights being measured parallelly to a stacking direction of the plates.

[0021] This corresponds to a first embodiment of the cooling system, wherein one of the top plates is thinner than the other. For instance, the first top plate is thinner than the second plate because it has been flattened during the machining operation.

[0022] According to an optional characteristic of the invention, the first top plate and the second top plate are of the same height, such height being measured parallelly to a stacking direction of the plates.

[0023] This corresponds to a second embodiment of the cooling system, in which the two top plates are of equal heights.

[0024] According to an optional characteristic of the invention, the marking is alongside an edge of the second top plate.

[0025] The marking is alongside an edge of the second top plate as opposed to a central portion of the second top plate. As a result, other components of the inverter can be positioned over the first top plate in a area which covers the central portion of the second top plate, without masking the marking. According to an optional characteristic of the invention, the first top plate comprises a flat zone configured to receive a power module, the through hole being outside of the flat zone in a peripheric zone.

[0026] The flat zone corresponds to the aforementioned area where other components of the inverter are positioned, in this case the power module. The through hole is not in the flat zone as it would otherwise be covered by the power module, which would make it impossible to see the marking through the through hole as the power module would obstruct the view.

[0027] According to an optional characteristic of the invention, the first top plate comprises at least one recess in the peripheric zone.

[0028] The recess is obtained by machining the first top plate. The recess corresponds to a localized reduction in the height of the top plate.

[0029] According to an optional characteristic of the invention, the plates are brazed together.

[0030] According to an optional characteristic of the invention, the plates are made of aluminum.

[0031] Aluminum is chosen to manufacture the plates as it has great cooling abilities and it facilitates heat transfers.

[0032] The invention is also relative to an inverter comprising a cooling system as previously described and a power module stacked on top of the first top plate of the cooling system, the power module comprising at least one connecting tab extending mainly parallelly to the first top plate, the connecting tab facing the recess of the first top plate.

[0033] The role of the power module of the inverter is for instance to switch electrical power on and off repeatedly, which results in the transformation of direct current into alternating current. Such conversion generates heat and consequently the power module needs to be cooled down, which is why it is placed on top of the cooling system. The power module comprises at least one connecting tab which links the power module to a direct current source. In order to avoid short-circuits within the inverter, this connecting tab is positioned over the recess formed within the first top plate, so that a distance between the connecting tab and the cooling system is increased.

[0034] The invention furthermore covers a process for obtaining a cooling system as previously described, comprising a manufacturing step of the plates with the cooling structures, a manufacturing step of the two top plates during which the marking is placed on the second top plate and during which the through hole is formed within the first top plate, a stacking step of the plates, a brazing step during which the stacked plates are brazed together, and a positioning step during which the brazed plates are inserted inside the housing.

[0035] During the process for obtaining a cooling system according to the invention, the plates are manufactured before being stacked so that the second top plate is placed over the plates with the cooling structures and the first top plate is placed over the second top plate. The plates are then assembled to one another by brazing and the stack of plates thus crated are positioned inside the housing, with the first top plate facing an exterior of the housing.

[0036] According to an optional characteristic of the invention, the process comprises a housing manufacturing step during which the housing is die-cast.

[0037] According to an optional characteristic of the invention, during the process at least one recess is machined in the first top plate.

[0038] The recess is more particularly machined after the positioning step.

[0039] Other characteristics, details and advantages of the invention will become clearer on reading the following description, on the one hand, and several examples of realisation given as an indication and without limitation with reference to the schematic drawings annexed, on the other hand, on which:

[0040] [Fig. 1] is a partially exploded view of a cooling system according to the invention, with a stack of plates shown outside of a housing of the cooling system;

[0041] [Fig. 2] is an exploded view of the stack of plates of Figure i, showing a first top plate, a second top plate and a plurality of plates with cooling structures; [Fig. 3] is a schematic representation of the cooling system of Figure 1, the stack of plates having been positioned into the housing and the first top plate having been machined;

[0042] [Fig. 4] is a schematic representation of an inverter according to the inven- tion, comprising the housing and the stack of plates of the cooling system of

[0043] Figure 1, a power module having been placed on top of the first top plate;

[0044] [Fig. 5] is a schematic representation of the stacking of the first top plate on top of the cooling system, in another embodiment.

[0045] The characteristics, variants and different modes of realization of the inven- tion may be associated with each other in various combinations, in so far as they are not incompatible or exclusive with each other. In particular, variants of the invention comprising only a selection of features subsequently described in from the other features described maybe imagined, if this selection of features is enough to confer a technical advantage and / or to differentiate the invention from prior art.

[0046] Like numbers refer to like elements throughout drawings.

[0047] Figures i to 3 illustrate, schematically, a cooling system 1 according to the invention. The cooling system 1 is destined to regulate a temperature of a power module 2 as shown on Figure 4, both the power module 2 and the cooling system 1 being part of an inverter 4. The inverter 4 is destined to equipe a motor vehicle, for instance an electric or hybrid motor vehicle. The inverter 4 is more particularly used to convert direct current supplied by batteries of the motor vehicle into alternating current, in order to power an electric motor of the vehicle.

[0048] The cooling system 1 comprises a plurality of plates, among which a plurality of plates with cooling structures 6 and a plurality of top plates 8. In some embodiments, the top plates 8 are smooth, which means that they have no cooling structures. In other embodiments, one of the top plates 8 may be smooth on one face and comprise cooling structures on the opposite face, as will be described hereinafter. All the plates are of a general rectangular shape and they have rounded corners. The plates are for instance made out of aluminum. They mainly extend along a longitudinal direction.

[0049] The plates with cooling structures 6 are configured for the circulation of a coolant fluid, whose role is to cool the power module 2. The cooling structures of the plates with cooling structures 6 are for instance meanderlike cooling structures. As can be seen on Figure 2, on a given plate with cooling structures 6 such cooling structures may be organized in groups, here with three groups of cooling structures aligned alongside the longitudinal direction.

[0050] The top plates 8 comprise a first top plate 8A and a second top plate 8B.

[0051] As is visible on Figure 2, the plates of the cooling system 1 also comprise a bottom plate 10. The plates are stacked over each other in the cooling system 1. More particularly, the plates with the cooling structures 6 are stacked on top of the bottom plate 10, the second top plate 8B is stacked on top of the plates with the cooling structures 6, and the first top plate 8A is stacked on top of the second top plate 8B.

[0052] In order to form the cooling system 1, the plates are placed inside a housing 12 of said cooling system 1. The plates are thus positioned within the housing 12 so that the bottom plate 10 is in contact with a bottom of the housing 12, while the first top plate 8A is the furthest from this bottom of the housing 12. The plates are represented outside of the housing 12 on Figure 1 and inside of it on Figure 3.

[0053] Each plate among the plates with the cooling structures 6, the top plates 8 and the bottom plate 10 has a first face 14 and a second face 16. These faces 14, 16 are opposed along a stacking direction of the plates; more precisely, the first face 14 is oriented towards the bottom of the housing 12 whereas the second face 16 is oriented opposite the bottom of the housing 12. As a result, the first face 14 of the bottom plate 10 is the one which it in contact with the bottom if the housing 12, and its second face 16 is the one in contact with one of the plates with a cooling structures 6. Similarly, the first face 14 of the second top plate 8B is in contact with one of the plates with the cooling structures 6 while its second face 16 is in contact with the first top plate 8A, and for the first top plate 8A its first face 14 is in contact with the second face 16 of the second top plate 8B.

[0054] As mentioned before, in some embodiments the top plates 8 are smooth in that both of their first face 14 and their second face 16 are smooth. In other embodiments, the second top plate 8B comprises cooling structures. In this case, its first face 14 has such cooling structures while its second face 16 is smooth.

[0055] In the embodiment illustrated on the figures, the first top plate 8A and the second top plate 8B are of the same height, such height being measured along the stacking direction of the plates. The height of the plates thus corresponds to their dimension measured between their first face 14 and their second face 16 perpendicularly to these faces 14, 16. However, in other embodiments not shown here, the first top plate 8A and the second top plate 8B could be of different heights.

[0056] As can be seen on Figures 3 and 4, the first top plate 8A comprises both a flat zone 18 and at least one recess 20. The flat zone 18 is a part of the first top plate 8A which is configured to receive the power module 2. The recess 20 is a part of the first top plate 8A which presents a reduced height. The recess 20 corresponds to a part of the first top plate 8A which is machined during a process for obtaining the cooling system i which will be described hereinafter. The recess 20 extends from the second face 16 towards the first face 14.

[0057] The flat zone 18 is in a central portion of the first top plate 8A, while the recess 20 is in a peripheric zone 22 surrounding the aforementioned central portion. Here, the first top plate 8 A comprises a plurality of recesses 20 positioned in the peripheric zone 22 around the flat zone 18.

[0058] According to the invention, the second top plate 8B comprises a marking 24. This marking 24 is a traceability marking such as a data matrix code. It is more particularly positioned on the second face 16 of the second top plate 8B, i.e. its face which faces the first top plate 8A. In addition, the marking 24 is placed alongside an edge 26 of the second top plate 8B. In other words, the marking 24 is closer to the edge 26 of the second top plate 8B than to its center. The edge 26 of the second top plate 8B faces the peripheric zone 22 of the first top plate 8A.

[0059] The first top plate 8 A comprises a through hole 28. This through hole 28 extends from the first face 14 to the second face 16, so that the first top plate 8A is pierced all the way through. The through hole 28 is more precisely positioned in the peripheric zone 22. In accordance with what has been described hereinbefore, the through hole 28 is thus outside of the flat zone 18. Additionally, the through hole 28 is outside of the recess 20

[0060] The position of the through hole 28 on the first top plate 8 A depends on the position of the marking 24 on the second top plate 8B. Indeed, the through hole 28 is positioned so that it faces the marking 24. As such, the marking 24 can be seen through the first top plate 8A.

[0061] As is visible on the figures, an area of the through hole 28 is bigger than an area of the marking 24, such areas being measured in planes perpendicular to the stacking direction. This allows an optimized visualization of the marking 24 despite the height of the first top plate 8A.

[0062] Another embodiment of the cooling system, according to the invention, is illustrated on figure 5. In this embodiment, the second top plate 8B comprises a cooling structure configured for a circulation of the coolant fluid through this top plate and a circulation of the coolant fluid from the second top plate 8B to the plates of the cooling structures 6. Other features of the cooling device are the same as disclosed in the previous embodiment.

[0063] In this embodiment, the through hole is formed thanks to a cut 29 in the first top plate 8A, as illustrated, with a direct access to the second top plate 8B.

[0064] On Figure 4, the cooling system 1 is shown as part of the inverter 4 which also comprises the power module 2. As the role of the cooling system 1 is to cool the power module 2 by circulating the coolant fluid inside the cooling structures of its plates with the cooling structures 6, the power module 2 is placed on top of the cooling system 1. The power module 2 is more precisely on top of the first top plate 8A, in contact with its second face 16. The power module 2 covers at least part of the flat zone 18.

[0065] The power module 2 comprises at least one connecting tab 30. Such connecting tab 30 helps connect a main body of the power module 2 to a current source, for instance a direct current source. The connecting tab 30 extends mainly perpendicularly to the main body of the power module 2, substantially parallelly to the first top plate 8A. As is visible on Figure 4, the connecting tab 30 of the power module 2 faces the recess 20 of the first top plate 8A. In other words, the connecting tab 30 extends over the recess 20. In the embodiments of the present invention where there are multiple connecting tabs 30, there are also multiple recesses 20, with each of the connecting tabs 30 facing one of the recesses 20.

[0066] The aforementioned process for obtaining the cooling system 1 will now be described. Such process relies on the manufacturing of both the housing 12 and the plates. To this end, the process comprises a first manufacturing step during which the housing 12 is die-cast. The process also comprises a second manufacturing step during which the plates are made out of aluminum. The cooling structures are added to the plates with the cooling structures 6. During this second manufacturing step, the marking 24 is implemented on the second top plate 8B and the though hole 28 is pierced within the first top plate 8 A, in an area of said first top plate 8 A which will cover the marking 28. In other embodiments, the first manufacturing step could correspond to the manufacturing of the plates while the second manufacturing step would correspond to the manufacturing of the housing. It is understood that either the housing or the plates may indifferently be manufactured first.

[0067] The plates are then stacked on top of each other, with the plates with the cooling structures 6 put on top of the bottom plate 10, the second top plate 8B put on top of the plates with the cooling structures 6 and the first top plate 8A put on the second top plate 8B. The first top plate 8A is positioned over the second top plate 8B so that the through hole 28 faces the marking 24; as such, the marking 24 is still visible when the top plates 8 are stacked. Once the plates have been stacked, the process continues with a brazing step during which the plates are brazed together.

[0068] The stack of plates which is thus formed is placed inside of the housing 12 during a positioning step, with the bottom plate 10 in contact with the bottom of the housing 12. The plates and the housing 12 are then welded together, for instance with a friction stir welding operation.

[0069] Once the plates and the housing 12 have been welded, the first top plate 8A is machined. Such machining causes a reduction in the height of the top plate 8A. The marking 24 is however protected as some height of the first top plate 8A remains after the machining; in other words, the machining does not create a hole in the first top plate 8A. The machining creates the flat zone 18 and it forms the recess 20. The power module 2 can then be positioned on top of the flat zone 18 of the first top plate 8A of the cooling system 1, with its connecting tab 30 extending over the recess 20 of the first top plate 8 A.

[0070] The present invention thus covers a cooling system in which a traceability marking stays visible even after the topmost surface has been machined, thus facilitating traceability operations to meet manufacturing requirements.

[0071] Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

CLAIMS1. Cooling system (1) for an inverter (4), comprising a housing (12) and a plurality of plates which are stacked together inside the housing (12), the plates comprising two top plates (8) and at least two plates with cooling structures (6) configured to disrupt the flow of a coolant of the cooling system (1), the top plates (8) comprising a first top plate (8A) stacked on top of a second top plate (8B), the second top plate (8B) being stacked on top of the plates with the cooling structures (6), the second top plate (8B) comprising a marking (24) and the first stop plate (8A) comprising an opening, in particular a through hole (28) facing the marking (24), in particular a cut.

2. Cooling system (1) according to the preceding claim, wherein the second top plate (8B) comprises a first face (14) facing one of the plates with the cooling structures (6) and a second face (16) facing the first top plate (8), the marking (24) being on the second face (16).

3. Cooling system (1) according to any of the preceding claims, wherein the first top plate (8A) and the second top plate (8B) are of different heights, such heights being measured parallelly to a stacking direction of the plates.

4. Cooling system (1) according to any of claims 1 and 2, wherein the first top plate (8A) and the second top plate (8B) are of the same height, such height being measured parallelly to a stacking direction of the plates.

5. Cooling system (1) according to any of the preceding claims, wherein the marking (24) is alongside an edge (26) of the second top plate (8B).

6. Cooling system (1) according to any of the preceding claims, wherein the first top plate (8A) comprises a flat zone (18) configured to receive a power module (2), the through hole (28) being outside of the flat zone (18) in a peripheric zone (22).

7. Cooling system (1) according to the preceding claim, wherein the first top plate (8A) comprises at least one recess (20) in the peripheric zone (22).

8. Cooling system (1) according to any of the preceding claims, wherein the plates are brazed together.

9. Cooling system (1) according to any of the preceding claims, wherein the plates are made of aluminum.

10. Inverter (4) comprising a cooling system (1) according to any of the preceding claims in combination with claim 7 and a power module (2) stacked on top of the first top plate (8A) of the cooling system (1), the power module (2) comprising at least one connecting tab (30) extending mainly par- allelly to the first top plate (8A), the connecting tab (30) facing the recess (20) of the first top plate (8A).

11. Process for obtaining a cooling system (1) according to any of claims 1 to 9, comprising a manufacturing step of the plates with the cooling structures (6), a manufacturing step of the two top plates (8) during which the marking (24) is placed on the second top plate (8B) and during which the through hole (28) is formed within the first top plate (8A), a stacking step of the plates, a brazing step during which the stacked plates are brazed together, and a positioning step during which the brazed plates are inserted inside the housing (12).

12. Process according to the preceding claim, comprising a housing manufacturing step during which the housing (12) is die-cast.

13. Process according to any of the preceding claims, during which at least one recess (20) is machined in the first top plate (8A).

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