Cooling system for a component comprising a cooling channel and a cooling structure
The cooling system with a stack of meander-shaped cells and an elastic recall means addresses the high manufacturing costs and inefficiencies of existing cooling structures by enhancing thermal conductivity and reducing air bubble interference.
Patent Information
- Application Number
- FR2023000626
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-01-24
- Publication Date
- 2025-02-07
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing cooling structures for power modules in electric current converters, such as inverters, are expensive to manufacture due to the need for brazing layers together to prevent air bubbles and thermal insulation, which reduces their cooling effectiveness.
A cooling system with a stack of layers featuring meander-shaped cells and an elastic recall means, such as a corrugated blade spring, is used to exert pressure between layers, eliminating the need for brazing and ensuring effective thermal conductivity without air bubbles.
The solution reduces manufacturing costs and enhances thermal conductivity by preventing air bubbles, thus improving the cooling efficiency of power modules.
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Abstract
Description
Title of the invention: Cooling system for a component comprising a cooling channel and a cooling structure
[0001] The invention relates to a cooling system, in particular for a power module, which may be included in an electric current converter such as an inverter. The invention is particularly applicable in a motor vehicle.
[0002] A power module is already known in the prior art which is directly cooled. This power module comprises a plate from which copper rods project. The rods are inserted through an opening into a flow path enclosure for a cooling fluid, such that the cooling fluid circulating in the flow path enclosure comes into contact with the rods.
[0003] To improve heat transfer, the applicant proposed, in international application WO 2022 / 248427, a cooling structure comprising several layers stacked on top of each other. Each layer comprises cells having at least two openings, at least one of which is in communication with a cell of another layer. Thus, the cooling fluid circulates within a cell and between two cells of different layers. Each cell has a meander-shaped portion in order to block a direct path of the fluid between the two openings. This cooling structure, in which turbulence is created in the cooling fluid, improves the heat transfer between the cell wall and the cooling fluid.
[0004] In this cooling structure, it is necessary to connect the layers together in order to improve thermal conductivity. This prevents cooling fluid, or air bubbles, from getting between the layers, preventing contact between the layers, thus reducing their effectiveness in cooling the power module. Furthermore, the cooling liquid between the layers, as well as the air bubbles, would constitute a thermal insulator. It could be considered to connect the different layers together by brazing. However, this way of connecting the layers together would be expensive.
[0005] The invention aims in particular to provide a cooling system comprising a cooling structure in which the bonding of the layers together is less expensive. Consequently, the cooling structure and the cooling system have a lower manufacturing cost.
[0006] To this end, the invention relates to a system for cooling a component comprising: - a cooling channel comprising a so-called lower wall, - a cooling structure comprising a stack of layers stacked on top of each other, in which each layer comprises cells each having at least one opening in communication with a cell of another layer, said cells having a meander-shaped portion, in which the layers are intended to be stacked between an interface plate with the component, called an interface plate, and the lower wall of the cooling channel. The cooling system further comprises an elastic return means configured to exert pressure between the bottom wall of the cooling channel and the stack of layers.
[0007] By exerting pressure between the bottom wall and the stack of layers, pressure is exerted both between the stack of layers and the interface plate and between the different layers. This tightens the layers together, and the stack of layers with the interface plate. This prevents the installation of air bubbles and coolant between the different layers, thus improving the thermal conductivity within the cooling structure, and therefore its efficiency.
[0008] Thus, it is not necessary to solder the different adjacent layers to connect the layers together. The cooling structure is easy to manufacture and has a low manufacturing cost. The same applies to the cooling system.
[0009] It is understood that when the cooling structure is mounted in contact with the component to be cooled, the layers are then stacked and pressed against the interface plate, thanks to the elastic return means which can bear against the lower wall to exert its return force against an end layer of the stack, called the lower layer, which transmits this force to the other layers up to a so-called upper layer, arranged at the opposite end of the stack relative to the lower layer and covered by the interface plate.
[0010] The term "cooling channel" means a structure configured to guide a cooling fluid. The cooling channel comprises a cavity with a general cooling fluid inlet and at least one general cooling fluid outlet. It is understood that the cavity is delimited, at least partially, by the lower wall and the upper layer, the cooling fluid circulating between the two.
[0011] It is understood that "a meander-shaped portion" is a portion comprising at least one change of direction in a plane perpendicular to the stacking direction, preferably a curvature. Curvature is understood to mean a single or several curves.
[0012] “A stack of layers” means at least two superimposed layers, for example at least three layers.
[0013] In one embodiment, each cell has two openings and the cells have a meander-shaped portion so as to block a direct path of a cooling fluid between the two openings.
[0014] In another embodiment, the cells in two different layers have differently arranged openings. Thus, the fluid creates turbulence as it passes from one layer to another.
[0015] The interface plate may be part of the cooling structure. It may also be part of the component.
[0016] The interface plate and the bottom wall can ensure the sealing of the cooling structure.
[0017] The lower wall, like the interface plate, is preferably made from a thermally conductive material, for example a metal or aluminum. Thanks to the invention, it is thus possible to mix the materials in such a way as to provide a gain in cost and / or performance.
[0018] The return means may be integrated into the lower wall, i.e. constitute a single part with the lower wall, or constitute at least one part separate from the lower wall.
[0019] In general, the coolant is a liquid coolant, for example oil, water or a mixture of water and glycol, it can also be a liquid-gas mixture such as a two-phase refrigerant. For example, the coolant can enter the cooling channel at one of its ends and exit at its opposite end.
[0020] The cooling system can be used to cool several components such as the main bodies of the power modules, for example three adjacent components.
[0021] Preferably, each layer comprises cells each having at least one opening in communication with a cell of an adjacent layer.
[0022] According to other optional features of the cooling system, taken alone or in combination:
[0023] - The return means consists of at least one part, and this part is attached between the bottom wall and the stack of layers. The return means can thus be manufactured from a material different from the material of the bottom wall and the stack of layers, having the flexibility characteristics suitable for this use. Furthermore, it is thus not necessary to develop a cooling channel specifically for this cooling system. For example, the cooling channel could be a cooling chamber with a cavity that was intended for a plate with copper rods. The layers would then extend into the cavity, instead of the copper rods.
[0024] - The return means is configured to press at several points on the stack of layers. By distributing the support points, uniform support is obtained, which optimizes contact between the different layers.
[0025] - The return means may be a wave-shaped leaf spring. These springs have the advantage of being easy to assemble and ensuring good distribution of support.
[0026] - The lower wall comprises on its surface facing the stack of layers a peripheral shoulder, and the wave leaf spring is configured to press at several points on the peripheral shoulder. The support points are thus distributed around the periphery of the lower wall. It is understood that the corrugated blade is shaped to follow the shape of the peripheral shoulder. The peripheral shoulder may have the shape of a rectangle with a central recess. In this configuration, the corrugated leaf spring has substantially the shape of a rectangle with a central recess, in which the two longitudinal ends of the blade are not necessarily joined.
[0027] - The layers have dimensions greater than those of the outer contour of the peripheral shoulder. We thus understand that the support points are distributed around the periphery of the layers but that they are nevertheless surrounded by a zone of the layers which is located even further out than the support points. By "dimensions of the layers" we mean their length and width, not their thickness. In other words, the layers completely cover the peripheral shoulder and extend beyond this shoulder.
[0028] - The return means is prestressed inside the lower wall.
[0029] The invention also relates to a power module comprising: - a main body, and - a cooling system as defined above, attached to the main body. The main body may include a base, which constitutes the interface plate, against which the cooling structure is pressed and preferably fixed. The power module may comprise controlled switches, for example controlled semiconductor switches, such as insulated gate bipolar transistors (IGBTs, Insulated Gate Bipolar Transistors or MOSFETs (SIC)). The power module may be configured to convert a direct current applied to its input into an alternating current available at its output, by controlling the controlled switches, in a manner known to those skilled in the art. Alternating current can be a multi-phase current, for example a current three-phase. The power module may comprise two cooling systems according to the invention, in particular one system fixed on one face of the main body of the power module and the other fixed on the opposite face of the main body.
[0030] The invention also relates to an electric current converter, in particular an inverter, comprising a power module as defined above. The electrical power converter may be an inverter. The inverter may be configured to convert direct current to alternating current using the power module or multiple power modules. The inverter may include a direct current link capacitor to smooth the direct current applied to the inverter.
[0031] The invention also relates to an electric drive module comprising an electric current converter as defined above and an electric motor controlled by the electric current converter.
[0032] The invention also relates to a motor vehicle comprising an electric drive module as defined above, for example configured to control at least one wheel of the motor vehicle.
[0033] The invention also relates to a method of assembling a cooling system as defined above, comprising the following steps: - the lower wall of the cooling channel and the elastic return means are assembled, and - the layers are stacked between the elastic return means and an interface plate.
[0034] The assembly of the lower wall and the elastic return means can be carried out at the time of their manufacture, the lower wall and the elastic return means being able to constitute only one and the same part.
[0035] The elastic return means may be prestressed.
[0036] The method may further comprise a step of fixing the lower wall with the interface plate. This fixing may be carried out by friction welding. Brief description of the figures
[0037] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:
[0038] [Fig-1] is a schematic sectional view of a cooling system of a component of the state of the art;
[0039] [Fig.2] is a schematic sectional view of a cooling system of a component according to the invention;
[0040] [Fig.3] is a perspective view of the cooling system of [Fig.2]. Detailed description
[0041] [Fig. 1] shows a cooling system of the state of the art for a component not shown. The cooling system is designated by the general reference 10. The cooling system 10 makes it possible to cool a power module, not shown, which can be included in an electric current converter such as an inverter. The cooling system 10 is more particularly usable in a motor vehicle. The cooling system 10 comprises a cooling channel 12. The cooling channel is a structure for guiding a cooling fluid. In general, the cooling fluid is a coolant, for example water or a mixture of water and glycol, it can also be a liquid-gas mixture such as a two-phase refrigerant.
[0042] The cooling channel 12 comprises a cavity 14 and a general inlet 16 for cooling fluid as well as at least one general outlet 18 for cooling fluid. The cooling channel 12 comprises a lower wall 20, which partially delimits the cavity 14.
[0043] The cooling system 10 also comprises a cooling structure 22, which comprises a stack 24 of layers 26 stacked on top of each other. A stack of layers comprises at least two superimposed layers. Each layer 26 comprises cells, not shown, and each cell has at least one opening in communication with a cell of another layer 26. The cells have a meander-shaped portion, that is to say a portion comprising at least one change of direction in a plane perpendicular to the stacking direction. The change of direction is for example a curvature. The layers 26 are intended to be stacked between an interface plate with the component, called interface plate 28, and the lower wall 20 of the cooling channel 12. In the cooling system of [Fig. 1], the interface plate 28 is part of the cooling structure 22.It could also be part of the component to be cooled.
[0044] In this state-of-the-art cooling system, the layers are connected to each other, for example by brazing, in order to improve thermal conductivity.
[0045] Figures 2 and 3 show a cooling system according to the invention. In these figures 2 and 3, elements similar to those of [Fig. 1] are designated by identical references.
[0046] In [Fig.2], the cooling system 10 according to the invention is shown with an additional element. The element 30 symbolizes an elastic return element 30, an example of which is shown in [Fig.2]. The elastic return means 30 is configured to exert pressure between the lower wall 20 of the cooling channel 12 and the stack 24 of layers 26.
[0047] In the example shown in [Fig.2], the return means 30 constitutes a part separate from the lower wall 20. It is attached between the lower wall 20 and the battery 24 of layers 26. It could also be integrated into the lower wall 20. In this example, it is a wave-shaped leaf spring. This wave-shaped leaf spring 30 ensures good distribution of the supports. It is configured to press at several points of the stack 24 of layers 26.
[0048] In the example of [Fig. 2], the lower wall 20 of the cooling channel 12 comprises a surface 32 oriented towards the stack 24 of layers 26. On this surface 32, the lower wall 20 comprises a peripheral shoulder 34 visible on the right part of the figure. The shoulder is not visible on the left part because it is pierced by a cooling fluid inlet 35. The corrugated leaf spring 30 is configured to press at several points on the peripheral shoulder 34. As seen in [Fig. 2], the corrugated leaf spring 30 may have substantially the shape of a rectangle with a central recess. The corrugated leaf 30 is shaped to follow the peripheral shoulder 34 which in this example has the shape of a rectangle with a central recess. In the example shown, the leaf 30 has two longitudinal ends which are not contiguous. The blade could also be shaped like a closed rectangle.
[0049] In this example, the layers 26 have dimensions greater than those of the outer contour 36 of the peripheral shoulder 34. “Dimensions of the layers” means their length and their width, and not their thickness. It is thus understood that the support points are distributed around the periphery of the layers 26 but that they are nevertheless surrounded by a zone of the layers 26 which is located even further out than the support points. The layers 26 completely cover the peripheral shoulder 34 and extend beyond this shoulder.
[0050] In the example of [Fig. 2], the return means 30 is prestressed inside the lower wall 20. The assembly of the lower wall 20 and the elastic return means 30 can be carried out at the time of their manufacture, the lower wall 20 and the elastic return means 30 being able to constitute only one and the same part
[0051] To assemble the cooling system 10, the lower wall 20 of the cooling channel 12 and the elastic return means 30 are assembled, and the layers 26 are stacked between the elastic return means 30 and the interface plate 28.
[0052] The assembly of the lower wall 20 to the interface plate 28 can be carried out by friction welding. In this example, the friction welding is continuous over the entire surface forming the junction between the interface plate 28 and the lower wall 20.
[0053] The cooling system 10 may equip a power module which comprises a main body not shown. In the power module, the cooling system 10 is attached to the main body.
[0054] The main body of the power module may comprise a base, which constitutes the interface plate 28, against which the cooling structure 22 is
[0055]
[0056]
[0057]
[0058] plated and preferably fixed. The power module may comprise controlled switches, for example controlled semiconductor switches, such as insulated gate bipolar transistors (IGBTs, Insulated Gate Bipolar Transistors or MOSFETs (SiC)). The power module may be configured to convert a direct current applied to its input into an alternating current available at its output, by controlling the controlled switches, in a manner known to those skilled in the art. The alternating current may be a multiphase current, for example a three-phase current. The power module may comprise two cooling systems 10, in particular one system 10 fixed on one face of the main body of the power module and the other 10 fixed on the opposite face of the main body. The power module may be included in an electrical power converter. The electrical power converter may be an inverter. The inverter may be configured to convert direct current to alternating current using the power module or multiple power modules. The inverter may include a direct current link capacitor to smooth the direct current applied to the inverter. The electric current converter may be part of an electric drive module, which also includes an electric motor controlled by the electric current converter. The electric drive module may be provided in a motor vehicle, in which it is, for example, configured to control at least one wheel of the motor vehicle. The invention is not limited to the embodiment presented and other embodiments will become apparent to those skilled in the art. List of references 10: cooling system of a component 12: Cooling channel 14: Cooling channel cavity 16: general coolant inlet 18: general coolant outlet 20: lower wall of the cooling channel 22: cooling structure 24: stack of diapers 26: layer 28: interface plate 30: elastic return means 32: surface of the lower wall facing the stack of layers 34: peripheral shoulder of the surface of the lower wall facing the stack of layers 35: coolant inlet 36: outer contour of the peripheral shoulder
Claims
Claims
1. Cooling system (10) of a component comprising: - a cooling channel (12) comprising a so-called lower wall (20), - a cooling structure (22) comprising a stack (24) of layers (26) stacked on top of each other, in which each layer (26) comprises cells each having at least one opening in communication with a cell of another layer (26), said cells having a meander-shaped portion, in which the layers (26) are intended to be stacked between an interface plate (28) with the component, called interface plate, and the lower wall (20) of the cooling channel (12), the cooling system (10) further comprising an elastic return means (30) configured to exert pressure between the lower wall (20) of the cooling channel (12) and the stack (24) of layers (26).
2. Cooling system (10) of a component according to claim 1, in which the return means (30) consists of at least one part, and this part is attached between the lower wall (20) and to the stack (24) of layers (26).
3. Cooling system (10) of a component according to any one of the preceding claims, in which the return means (30) is configured to press at several points of the stack (24) of layers (26).
4. Cooling system (10) of a component according to the preceding claim, in which the return means (30) is a wave-shaped leaf spring.
5. Cooling system (10) of a component according to the preceding claim, in which the lower wall (20) comprises on its surface (32) facing the stack (24) of layers (26) a peripheral shoulder (34), and the wave-shaped leaf spring (30) is configured to press at several points of the peripheral shoulder (34).
6. Cooling system (10) of a component according to the preceding claim, in which the layers (26) have dimensions greater than those of the outer contour (36) of the peripheral shoulder (34).
7. Cooling system (10) of a component according to any one of claims 2 to 6, in which the return means (30) is prestressed inside the bottom wall (20).
8. Power module comprising: - a main body, and - a cooling system (10) according to any one of the preceding claims, fixed to the main body.
9. Electric current converter, in particular inverter, comprising a power module according to claim 8.
10. Method of assembling a cooling system (10) according to any one of claims 1 to 7, comprising the following steps: - assembling the lower wall (20) of the cooling channel (12) and the elastic return means (30), and - stacking the layers (26) between the elastic return means (30) and an interface plate (28).