Heat exchanger

Abstract

A heat exchanger for a power module of an inverter system is disclosed. The heat exchanger includes a body defining an inlet and an outlet. At least one closed channel is integrally formed within the body, the at least one closed channel being in fluid communication with the inlet and the outlet.

Description

Technical Field

[0001] The present invention relates to a heat exchanger for a power module. The present invention also relates to a power module including the heat exchanger, and to a method of manufacturing the heat exchanger. Background Art

[0002] Power modules are typically used in inverter systems. The power module is used to convert the power source from AC to DC and ensure that power is supplied to components such as electric motors at the correct voltage and current.

[0003] The power module generates heat during use, which may lead to overheating. Overheating is undesirable because it may damage the function of the power module and ultimately cause the failure of the power module. Heat is usually extracted by a suitable heat exchanger to reduce the likelihood of overheating. Conventional heat exchangers operate by supplying a fluid to the heat exchanger so that the heat generated by the power module is transferred to the fluid. The heat exchanger needs to be properly sealed to prevent moisture from transferring from the heat exchanger to the power module.

[0004] The present invention seeks to eliminate or at least mitigate the problems associated with known devices, whether identified herein or otherwise. Summary of the Invention

[0005] According to a first aspect of the present invention, there is provided a heat exchanger for a power module of an inverter system. The heat exchanger includes a body defining an inlet and an outlet. At least one closed channel is integrally formed within the body, and the at least one closed channel is in fluid communication with the inlet and the outlet.

[0006] The at least one enclosed channel can be understood to mean that the channel is enclosed to define the flow area of the channel, but the channel can receive fluid from the inlet, and the fluid can be discharged from the body via the outlet.

[0007] The body may include an inlet connector. The inlet connector may be provided in the area of the inlet. An inlet fluid line may be connectable to the inlet connector. The body may include an outlet connector. The outlet connector may be provided in the area of the outlet. An outlet fluid line may be connectable to the outlet connector.

[0008] Since the closed channel is integrally formed with the body, no separate parts of the body are required, and thus no seals are required between the parts of the body. This is desirable because the presence of seals poses a risk of fluid leakage through at least one channel. The leaked fluid may damage the power module due to, for example, corrosion. Therefore, the closed channel integrally formed with the body reduces the likelihood of leakage, resulting in a more robust heat exchanger than conventional heat exchangers.

[0009] The at least one channel may define a tortuous path.

[0010] In the case where the channels define a tortuous path, the heat exchanger can extract more heat from the power module compared to the case where the channels define, for example, a linear path. This is because the path length of the channels is increased due to the tortuous path. Therefore, in the case where at least one channel defines a tortuous path, the heat exchanger can operate more efficiently.

[0011] The width of at least one channel can be constant along the length of at least one channel.

[0012] The width of at least one channel can be constant along the entire length of at least one channel.

[0013] In the case where the width of at least one channel is constant, the heat exchanger can extract heat from the power module more efficiently. This is because the heat extraction is more uniform compared to the case where the width of the channel is not constant.

[0014] A plurality of closed channels, an inlet manifold, and an outlet manifold can be formed in the body. Each of the plurality of channels can extend between the inlet manifold and the outlet manifold.

[0015] In the case of a plurality of channels extending between the inlet manifold and the outlet manifold, the heat exchanger can extract more heat from the power module compared to the case of providing a single channel. It should be understood that when the fluid travels through the heat exchanger, the temperature of the fluid increases. In the case of providing a plurality of channels extending between the inlet manifold and the outlet manifold, the distance that the fluid travels as it passes through the channels can be optimized. This allows for improved cooling of the power module in use.

[0016] In the case of providing a plurality of channels, each channel can have any of the features disclosed with respect to at least one channel.

[0017] The heat exchanger can further include an inlet conduit that is directly sealingly engaged with the inlet and an outlet conduit that is directly sealingly engaged with the outlet.

[0018] Throughout this document, the phrase "directly sealingly engaged" can be understood to mean that no separate sealing member is provided separately between the inlet conduit or the outlet conduit and the inlet or the outlet. In other words, the inlet conduit and the outlet conduit extend in a continuous manner from the inlet and the outlet of the body.

[0019] The inlet conduit can include an inlet connector. An inlet fluid line can be connectable to the inlet connector. The outlet conduit can include an outlet connector. An outlet fluid line can be connectable to the outlet connector.

[0020] The inlet duct and the outlet duct can be directly and sealingly joined by any suitable process, such as, for example, a welding process such as rotary friction welding. Alternatively, the inlet duct and the outlet duct can be formed integrally with the body.

[0021] In a second aspect of the present invention, there is provided a power module for an inverter system. The power module includes a substrate, a heat exchanger according to the first aspect of the present invention. A first major surface of the body of the heat exchanger is in contact with the substrate. The power module further includes a lid that at least partially covers the substrate and the heat exchanger.

[0022] One or more chips can be fixed to the substrate. One or more chips can be fixed to the opposite side of the substrate that is in contact with the heat exchanger. In other words, one or more chips can be fixed to the first major surface of the substrate, and the heat exchanger can contact the second major surface of the substrate. The second major surface can be generally opposite to the first major surface.

[0023] The power module can be a power conversion module.

[0024] The first major surface of the heat exchanger can be in contact with the first major surface of the substrate.

[0025] It should be understood that the advantages discussed with respect to the first aspect of the present invention apply, mutatis mutandis, to the second aspect of the present invention.

[0026] The power module can further include an inlet duct and an outlet duct, the inlet duct being connected to the inlet of the body of the heat exchanger, and the outlet duct being connected to the outlet of the body of the heat exchanger.

[0027] The lid can at least partially cover or enclose the inlet duct and the outlet duct.

[0028] The inlet duct and the outlet duct can be directly and sealingly joined to the body of the heat exchanger.

[0029] In the case where the inlet duct and the outlet duct are directly and sealingly joined to the body of the heat exchanger, the likelihood of leakage is reduced compared to the case where a seal is provided between the inlet duct or the outlet duct and the lid. Thus, the inlet duct and the outlet duct being directly and sealingly joined to the body advantageously reduces the likelihood of fluid leakage from the power module. Damage to the power module can occur due to fluid leakage. Thus, the inlet duct and the outlet duct directly and sealingly joined to the body advantageously make the power module more robust.

[0030] The inlet duct can include an inlet connector, and the outlet duct includes an outlet connector. The inlet connector and the outlet connector can be spaced apart from the body of the heat exchanger.

[0031] An inlet fluid line can be connectable to the inlet connector. An outlet fluid line can be connectable to the outlet connector.

[0032] In the case of providing an inlet connector and an outlet connector spaced apart from the body of the heat exchanger, the possibility of damaging components of the power module is advantageously reduced. This is in comparison to the case where the connectors are adjacent to the body of the heat exchanger. This is because, when installed in the inverter system housing, the inlet connector and the outlet connector can be provided on opposite sides of the body of the heat exchanger (i.e., outside the housing). Thus, any fluid that does leak at the interface between the inlet fluid line or the outlet fluid line and the inlet connector or the outlet connector will not leak into the inverter system housing.

[0033] In the case where the inlet conduit and the outlet conduit are also directly sealingly engaged with the inlet and the outlet of the body respectively, the possibility of damaging components of the power module is further reduced. This is because, with this arrangement, when the power module is assembled into such a housing, no seals are provided within the inverter system housing. As discussed above, there is an opportunity for fluid leakage with seals.

[0034] In a third aspect of the present invention, a method of manufacturing a heat exchanger for a power module is provided. The method includes: forming at least one closed channel within the body such that the at least one closed channel is integrally formed with the body; and providing an inlet and an outlet for the body in fluid communication with the at least one closed channel.

[0035] The at least one closed channel can be formed within the body via friction stir channeling.

[0036] The method can further include directly sealingly engaging an inlet conduit with the inlet of the body and directly sealingly engaging an outlet conduit with the outlet.

[0037] Via a solid state welding process, the inlet conduit can be directly sealingly engaged with the inlet of the body and the outlet conduit can be directly sealingly engaged with the outlet.

[0038] The solid state welding process can be rotary friction welding

[0039] The method can further include fixing the body to a power module of an inverter system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Embodiments of the present invention will now be described with reference to the drawings, in which:

[0041] Figure 1 A perspective view of a power module according to an embodiment of the present invention is shown;

[0042] Figure 2 Is shown Figure 1 A cross-sectional view of the power module of

[0043] Figure 3 shows Figure 1 a top view of the heat exchanger of the power module of

[0044] Figure 4 shows the Figure 1 power module positioned in the housing;

[0045] Figure 5 shows a perspective view of a power module according to another embodiment of the present invention; and

[0046] Figure 6 shows Figure 5 a top view of the heat exchanger of the power module of Detailed Description

[0047] Figure 1 shows a power module 2 according to an embodiment of the present invention. The power module 2 includes a substrate (not visible in Figure 1 ), a heat exchanger 6, and a lid 8. One or more chips (not shown for clarity in Figure 1 ) are fixed to the substrate. The lid 8 is a molding compound. The lid 8 at least partially covers the substrate and the heat exchanger 6. The phrase "partially covers" means that not all sides are covered, for example, 5 out of 6 sides are covered. Additionally, the phrase can also mean that the entire surface of one of the sides may not be covered. The purpose of the lid 8 is to protect the other components of the power module 2 from environmental factors such as moisture and dust. The power module 2 is used in an inverter system (not shown), preferably in an inverter system used in a vehicle (not shown), preferably an electric vehicle. The inverter system includes a plurality of power modules 2, preferably three or six power modules 2. The power module 2 includes a plurality of connectors 10 (only one of the connectors is labeled in Figure 1 ). The plurality of connectors 10 are used to connect the power module 2 to an external power source (not shown) and to components (not shown) powered by the power source. The components can be an electric motor.

[0048] Figure 2A cross-sectional view of the power module 2 is shown. The heat exchanger 6 includes a body 12. The body 12 is generally plate-shaped. However, the body 12 can be of any suitable shape, such as disk-shaped. The body 12 is formed of a laminated structure. The body 12 formed of a laminated structure can be understood to mean that the body 12 is formed of a plurality of individually formed layers that are adhered to each other or otherwise adjacent. The body 12 includes an aluminum layer and a copper layer. The copper layer can be adjacent to or fixed to the substrate 4, and the aluminum layer can be adjacent to the copper layer. In some embodiments, the body 12 can include a plurality of copper layers with an aluminum layer sandwiched therebetween, or a plurality of aluminum layers with a copper layer sandwiched therebetween. The layers of the body 12 can be fixed to each other via integral bonding. In some embodiments, the body 12 can be formed of a single aluminum layer or a single copper layer. The body 12 includes a first major surface 14 and a second major surface 16. The first major surface 14 contacts the substrate 4. The body 12 defines an inlet 18 and an outlet 20. A plurality of closed channels 22 are formed within the body 12. The plurality of closed channels 22 are in fluid communication with the inlet 18 and the outlet 20. The plurality of closed channels 22 are integrally formed within the body 12 of the heat exchanger 6. The plurality of closed channels 22 are at least partially or completely enclosed by the body 12 of the heat exchanger 6. The plurality of enclosed channels 22 can be understood to mean that the channels are enclosed to define a flow region, but the channels 22 are capable of receiving fluid from the inlet 18 and discharging the fluid from the body 12 via the outlet 20.

[0049] The heat exchanger 6 further includes an inlet conduit 21 and an outlet conduit 24. The inlet conduit 21 is directly and sealingly engaged with the inlet 18 of the body 12 of the heat exchanger 6 and is configured to transfer fluid into the plurality of closed channels 22 via the inlet conduit 21 and the inlet 18. The outlet conduit 24 is directly and sealingly engaged with the outlet 20 of the body 12 of the heat exchanger 6 and is configured to discharge fluid from the plurality of closed channels 22 via the outlet 20 and the outlet conduit 24. Throughout this application, the phrase "directly and sealingly engaged" can be understood to mean that no separate sealing member is provided between the inlet conduit 21 and the inlet 18 or between the outlet conduit 24 and the outlet 20. In other words, the inlet conduit 21 and the outlet conduit 24 each extend continuously from the inlet 18 and the outlet 20 of the body 12, respectively.

[0050] The inlet conduit 21 includes an inlet connector 23. The outlet conduit 24 includes an outlet connector 25. The inlet connector 23 and the outlet connector 25 each define a plurality of ribs 27, 29. The inlet fluid line ( Figure 3 not shown in the figure) can be connected to the inlet connector 23, and the outlet fluid line ( Figure 3(not shown) may be connected to the outlet connector 25. When connected to the inlet connector 23 or the outlet connector, the inlet fluid line and the outlet fluid line engage corresponding multiple ribs 27, 29, which increases the force required to disconnect the inlet fluid line from the inlet connector 23. This reduces the likelihood of fluid leakage at the interface between the inlet or outlet fluid line and the inlet or outlet connector. In some embodiments not depicted, the inlet connector and the outlet connector may each take any other suitable form that allows the inlet line and the outlet line to engage the inlet conduit and the outlet conduit, respectively. In some embodiments, it is not necessary to provide the inlet conduit and the outlet conduit.

[0051] Figure 3 A cross-sectional view of the heat exchanger 6 is shown. Figure 3 The cross-sectional view is taken in a plane parallel to the first major surface (not visible in Figure 3 and the second major surface (not visible in Figure 3 of the body 12 of the heat exchanger 6. Each of the plurality of channels 22 extends between the inlet manifold 26 and the outlet manifold 28. Each of the plurality of channels 22 extends from the inlet manifold 26 to the outlet manifold 28. In some embodiments not depicted, only a single closed channel extending from the inlet 18 to the outlet 20 of the body 12 may be provided. In the case where a single channel is provided, it is not necessary to provide the inlet manifold 26 and the outlet manifold 28. In the case where a single channel is provided, the single channel may include any of the features disclosed herein with respect to the plurality of channels 22. Each of the plurality of closed channels 22 defines a tortuous path. In other words, each of the plurality of channels 22 defines a non-linear path. Compared with a linear path, the non-linear path increases the surface area of the edges (or sidewalls) of the closed channel 22. This improves the ability of the heat exchanger 6 to extract heat from the substrate ( Figure 3 not shown). The width of each of the plurality of channels 22 may be constant along its corresponding length. That is, the width of each channel is constant between the inlet manifold 26 and the outlet manifold 28. The width of the channel refers to the minimum distance measured between the sidewalls of each channel in a plane parallel to the first major surface 14 of the body 12. However, according to another embodiment of the present invention, the width of each channel may be variable and may be customized (or tailored) based on the configuration of the circuitry of the power module, for example, by having more, narrower (i.e., smaller spacing between the sidewalls of the channel) closed channels 22 in areas of the circuitry that require more heat dissipation capacity, and having fewer, wider (i.e., larger spacing between the sidewalls of the channel) closed channels in areas of the circuitry that have fewer components generating less heat.

[0052] Figure 4 A power module 2 assembled into a housing 30 is shown. The housing 30 may be referred to as an inverter housing.Figure 4 Also shown are an inlet fluid line 31 connected to the inlet connector 23 and an outlet fluid line 33 connected to the outlet connector 25. The housing 30 is used to protect the power module 2 from, for example, impacts, dust, and moisture during use. The housing 30 is hermetically sealed. The housing 30 includes a first hole 32 and a second hole 34. The inlet conduit 21 extends through the first hole 32. The outlet conduit 24 extends through the second hole 34. A first sealing member 36 is provided between the inlet conduit 21 and the first hole 32. The first sealing member 36 seals the inlet conduit 21 and the housing 30, particularly the first hole 32. A second sealing member 38 is provided between the outlet conduit 24 and the second hole 34. The second sealing member 38 seals the outlet conduit 23 and the housing 30, particularly the second hole 34. The purpose of the first sealing member 36 and the second sealing member 38 is to prevent dust and / or moisture from entering the housing 30. Thus, the first sealing member 36 and the second sealing member 38 reduce the likelihood of damage to the power module 2 during use.

[0053] From Figure 4 As can be seen, the inlet connector 23 and the outlet connector 25 are provided outside the housing 30. This is desirable because if fluid leaks at one or both of the inlet connector 23 and the outlet connector 25, the likelihood of damage to the power module 2 caused by the leaked fluid is reduced. This is in comparison to the case where one or both of the connectors are provided inside the housing 30. In some embodiments discussed below, the inlet connector 23 and the outlet connector 25 do not need to be provided outside the housing 30.

[0054] For manufacturing the heat exchanger 6, a blank body 12 is provided. The body 12 being a blank means that there are no multiple closed channels 22 within the body 12 and no inlet 18 and outlet 20. Thus, at this manufacturing stage of the heat exchanger, the body 12 or each layer of the body 12 in the case where the body 12 is formed of a laminated structure is continuous. In the case where the body 12 is not formed of a laminated structure, the blank body 12 can be provided as a solid material block. Multiple closed channels 22 are formed within the body 12. Then, friction stir channeling is used to form multiple closed channels 22 within the body. In some embodiments, only a single channel is provided. Friction stir channeling is a process in which a probe or tool rotates at a high speed while passing through a workpiece. An initial contact period is allowed to generate enough heat to soften the workpiece so that the probe can enter the workpiece. The movement of the probe through the workpiece results in the formation of closed channels within the workpiece. To form closed channels in the body 12, the tool can have a rotational speed of at least 400 revolutions per second and / or up to 600 revolutions per second. Additionally, the probe can have a translational speed of at least 25 mm / minute and / or up to 50 mm / minute. The use of friction stir channeling allows multiple closed channels 22 to be formed integrally with the body 12.

[0055] In the case where the body 12 is formed of a laminated structure, a plurality of closed channels 22 are preferably formed in the aluminum layer of the body 12. As discussed above, in the case where the body 12 is formed of a laminated structure, the laminated structure includes an aluminum layer and a copper layer. Preferably, a plurality of channels are formed in the aluminum layer because this reduces the risk of corrosion of the body 12 compared to the case where the channels are formed in the copper layer. Once a plurality of closed channels 22 have been formed within the body 12, an inlet 18 and an outlet 20 are provided to the body 12. Once provided, the inlet 18 and the outlet 20 are in fluid communication with the plurality of closed channels 22. In some embodiments, the inlet 18 and the outlet 20 may be provided to the body 12 before providing the plurality of channels 22 to the body. The inlet 18 and the outlet 20 may be formed, for example, by milling.

[0056] Next, an inlet conduit 21 and an outlet conduit 24 are fixed to the body 12 such that they are in direct sealing engagement with the inlet 18 and the outlet 20, respectively. The inlet conduit 21 and the outlet conduit 24 are fixed to the body 12 via rotary friction welding. Rotary friction welding is a process in which one part of the workpiece remains stationary while another part of the workpiece rotates at a high speed. Then the parts are brought into contact, generating friction. The friction generated between the two parts of the workpiece generates heat, which softens the workpiece. Then the workpieces are moved towards each other and welded together. Advantageously, rotary friction welding is used to connect the inlet conduit 21 and the outlet conduit 24 to the inlet 18 and the outlet 20, respectively, eliminating the need to provide separate sealing members at the interfaces between the inlet conduit 21 and the inlet 18 and between the outlet conduit 24 and the outlet 20. In other embodiments, the inlet conduit 21 and the outlet conduit 24 may be connected to the inlet 18 and the outlet 20, respectively, via any other suitable method that allows for direct sealing engagement between the inlet conduit 21 and the inlet 18 and between the outlet conduit 24 and the outlet 20. The inlet conduit 21 and the outlet conduit 24 may be connected to the inlet 18 and the outlet 20, respectively, via any suitable solid-state welding process, such as ultrasonic welding. Alternatively, via a fusion welding process, the inlet conduit may be connected to the inlet 18 and the outlet conduit 24 may be connected to the outlet 20.

[0057] Then, the heat exchanger 6 is brought into contact with the substrate 4 such that a first major surface 14 of the body 12 of the heat exchanger 6 contacts the substrate 4. The body 12 may be fixed to the substrate 4 via any suitable means, such as by using solder, sintering, and / or an adhesive. The body 12 is preferably fixed to the copper layer of the body 12, but may be fixed to the aluminum layer.

[0058] In other embodiments, the heat exchanger 6 may be manufactured via 3D printing.

[0059] Figure 5Another embodiment of the power module 102 is shown. In this embodiment, the inlet conduit 121 and the outlet conduit 124 are shorter than those inlet and outlet conduits in the previous embodiment. Thus, when the power module 102 is assembled into a housing ( Figure 5 not shown), the inlet connector 123 and the outlet connector 125 are disposed within the housing. Since the inlet conduit 121 and the outlet conduit 124 have a shorter length, the inlet connector 123 and the outlet connector 125 can be referred to as being adjacent to the body 112 of the heat exchanger 106. A reservoir (not depicted) can be connected to the inlet connector 123 and the outlet connector 125 such that the reservoir is in fluid communication with a plurality of channels (not Figure 5 visible in).

[0060] Figure 6 A cross-sectional view of the heat exchanger 106 of the power module 102 is shown. Figure 6 The cross-section is taken in a plane parallel to the second major surface (not Figure 6 visible in, which is outside the plane of the view). In this embodiment, the inlets 118 and the outlets 120 of the body 112 are stadium-shaped. However, the inlets 118 and the outlets 120 can be of any suitable shape, such as circular. Except for the features identified herein, the features of the heat exchanger 106 are the same as the features of the heat exchanger 6. The heat exchanger 106 can include any of the features discussed above with respect to the heat exchanger 6. The heat exchanger 106 is advantageously manufactured more efficiently than the heat exchanger 6.

[0061] While specific embodiments of the invention have been described above, it should be understood that the invention can be practiced in other ways than those described. The above description is intended to be illustrative and not restrictive. Thus, it will be apparent to those skilled in the art that the described invention can be modified without departing from the scope of the claims set forth below.

Claims

1. A heat exchanger for a power module of an inverter system, the heat exchanger comprising: a main body, the main body defining an inlet and an outlet; At least one enclosed channel is integrally formed in the body, the at least one enclosed channel being in fluid communication with the inlet and the outlet.

2. A heat exchanger according to claim 1 or claim 2, wherein the at least one channel defines a tortuous path.

3. A heat exchanger according to claim 1 or claim 2, wherein the width of the at least one channel is constant along the length of the at least one channel.

4. A heat exchanger according to any preceding claim, wherein a plurality of enclosed channels, an inlet manifold and an outlet manifold are formed in the body, and wherein each channel of the plurality of channels extends between the inlet manifold and the outlet manifold.

5. A heat exchanger according to any preceding claim, further comprising an inlet conduit in direct sealing engagement with the inlet, and an outlet conduit in direct sealing engagement with the outlet.

6. A power module for an inverter system, the power module comprising: substrate; The heat exchanger according to any one of claims 1 to 4, wherein a first main surface of the main body of the heat exchanger is in contact with the substrate; and A cover at least partially covers the base plate and the heat exchanger. 7 . The power module according to claim 6 , further comprising an inlet conduit connected to the inlet of the main body of the heat exchanger and an outlet conduit connected to the outlet of the main body of the heat exchanger.

8. The power module of claim 7, wherein the inlet conduit and the outlet conduit are in direct sealing engagement with the body of the heat exchanger.

9. A power module according to claim 7 or claim 8, wherein the inlet conduit comprises an inlet connector and the outlet conduit comprises an outlet connector, and wherein the inlet connector and the outlet connector are spaced apart from the body of the heat exchanger.

10. A method for manufacturing a heat exchanger for a power module, the method comprising: forming at least one enclosed channel in the body such that the at least one enclosed channel is integrally formed with the body; The body is provided with an inlet and an outlet in fluid communication with the at least one enclosed passageway.

11. The method of claim 10, wherein the at least one closed channel is formed in the body via friction stir channelization.

12. A method according to claim 10 or claim 11, further comprising bringing an inlet conduit into direct sealing engagement with the inlet of the body, and bringing an outlet conduit into direct sealing engagement with the outlet conduit.

13. The method of claim 12, wherein the inlet conduit is brought into direct sealing engagement with the inlet of the body and the outlet conduit is brought into direct sealing engagement with the outlet conduit via a solid state welding process.

14. The method of claim 13, wherein the solid state welding process is spin friction welding.

15. The method according to any one of claims 10 to 14, further comprising securing the body to a power module for an inverter system.

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