A heat sink for coupling heat dissipation by using a gravity heat pipe and a liquid cooling structure
By coupling gravity heat pipes with liquid cooling structures and combining phase change working fluid with flowing coolant, the problem of poor heat exchange performance of existing radiators in air is solved, achieving efficient and compact heat dissipation while reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN CRRC TIMES ELECTRIC DRIVE TECHNOLOGY CO LTD
- Filing Date
- 2021-09-30
- Publication Date
- 2026-07-24
AI Technical Summary
Existing gravity heat pipe radiators have poor heat exchange performance in air, making it difficult to meet the heat dissipation requirements of high-power modules. In addition, traditional liquid cooling radiators have complex structures and high costs.
The gravity heat pipe is coupled with a liquid cooling structure. By setting grooves and fins on the heat dissipation substrate, and combining the liquid phase change working fluid with the flowing coolant, the coupling of phase change heat transfer and liquid cooling heat transfer is realized. The condensation section of the gravity heat pipe is immersed in the coolant.
It improves heat dissipation efficiency by more than 80%, has a compact structure, low cost, simple process, avoids thermal resistance, and can directly replace the existing structure.
Smart Images
Figure CN115915700B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of heat dissipation technology for power modules of new energy electric vehicles, specifically relating to a heat sink that uses gravity heat pipes and liquid cooling structure to achieve coupled heat dissipation. This heat sink is mainly used for heat dissipation of power modules for motor controllers. Background Technology
[0002] The application of power modules in electric vehicles (EVs) and hybrid electric vehicles (HEVs) includes their use in powertrain systems and charging equipment for delivering and controlling power to the electric motor. The rapid growth in demand for EVs and HEVs is the primary driver of the development of high-power module technology. Key criteria for evaluating automotive power modules, such as performance, efficiency, reliability, cost, and size / weight, are typically determined by power semiconductor devices, packaging, and manufacturing technologies. As motor controllers evolve towards higher integration and higher power output, the power requirements for power modules are increasing. Simultaneously, the demand for power modules is trending towards lightweighting and miniaturization, leading to increasingly stringent requirements for the heat exchange performance of heat sinks.
[0003] Traditional liquid-cooled heatsinks are increasingly insufficient to meet the heat dissipation requirements of power modules. Prolonged operation in high-temperature environments can easily damage these modules. Existing gravity heat pipe heatsinks are mostly made of aluminum fins, with the fins fixed to the condenser section of the heat pipe, relying on the good thermal conductivity of aluminum for heat dissipation. However, after heat is transferred to the aluminum fins, the heat transfer to the condenser section and fins relies entirely on convection from the surrounding air. Furthermore, most heatsinks are not exposed to the air but are installed inside the chassis. Due to the low airflow and low heat capacity of the air inside the chassis, the heat transfer coefficient between the gravity heat pipe and the air is even lower, resulting in less than ideal overall heat dissipation. Therefore, there is an urgent need for a heat dissipation structure that offers high heat dissipation performance, a compact structure, and does not require replacement of existing packaging technology. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a heat sink with a compact structure, convenient installation and high heat dissipation performance that uses gravity heat pipe and liquid cooling structure to achieve coupled heat dissipation.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0006] A heat sink that utilizes a gravity heat pipe and a liquid cooling structure for coupled heat dissipation includes: a heat dissipation substrate, a heat dissipation plate, and a cover. The lower and upper surfaces of the heat dissipation plate are connected to the upper surface of the heat dissipation substrate and the cover, respectively. A power module is provided on the lower surface of the heat dissipation substrate. The upper surface of the heat dissipation substrate and the heat dissipation plate form a gravity heat pipe. The condensation section of the gravity heat pipe is encapsulated in the cover. A flowing coolant is introduced into the cover so that the condensation section of the gravity heat pipe is immersed in the coolant.
[0007] As a further improvement of the present invention, the upper surface of the heat dissipation substrate is provided with a first groove, which is used to hold a liquid phase change working fluid.
[0008] As a further improvement of the present invention, the bottom of the first groove is provided with a plurality of solid heat dissipation pins, which are used to enhance the heat exchange between the liquid phase change working fluid and the heat dissipation substrate.
[0009] As a further improvement of the present invention, the heat sink is provided with a second groove, and the first groove and the second groove are in communication.
[0010] As a further improvement of the present invention, the second groove is provided with a plurality of hollow heat dissipation pins, each hollow heat dissipation pin having an inner hole that communicates with the second groove; the first groove, the second groove, and the inner hole of the pin form a gravity heat pipe, the second groove and the inner hole of the pin serving as the condensation section of the gravity heat pipe, the liquid phase change working fluid in the first groove is heated and changes to a gaseous working fluid before entering the second groove and the inner hole of the pin, thereby achieving the condensation of the phase change working fluid.
[0011] As a further improvement of the present invention, a through hole is provided at the top of any hollow heat dissipation fin located at the end of the second groove. The gravity heat pipe formed by the first groove, the second groove and the inner hole of the fin is evacuated through the through hole, and a liquid phase change working fluid is injected into the gravity heat pipe through the through hole.
[0012] As a further improvement of the present invention, the cover includes a coolant inlet, a coolant outlet and a cavity, and the condensation section of the gravity heat pipe is encapsulated in the cavity.
[0013] As a further improvement of the present invention, the cover is provided with a third groove, and a sealing element is provided in the third groove to achieve a sealed connection between the cover and the upper surface of the heat sink.
[0014] As a further improvement of the present invention, the power module includes a power chip, a packaging component, an input copper busbar and an output copper busbar. The packaging component is connected to the lower surface of the heat dissipation substrate, and the power chip is provided on the packaging component. The input copper busbar and the output copper busbar are respectively located at opposite ends of the packaging component.
[0015] As a further improvement of the present invention, the lower surface of the heat sink is welded to the upper surface of the heat sink substrate.
[0016] As a further improvement of the present invention, the upper surface of the heat sink is detachably connected to the cover.
[0017] Compared with the prior art, the advantages of the present invention are as follows:
[0018] This invention utilizes a gravity heat pipe and a liquid cooling structure to achieve coupled heat dissipation in a heat sink. By providing a power module on the lower surface of the heat sink substrate, the heat sink substrate and the heat sink plate are integrated by welding. The upper surface of the heat sink substrate and the heat sink plate form a gravity heat pipe. At the same time, the condensation section of the gravity heat pipe is encapsulated in a cover, and a flowing coolant is introduced into the cover, so that the condensation section of the gravity heat pipe is immersed in the coolant, achieving rapid heat dissipation. The heat sink achieves the coupling of two heat dissipation methods: phase change heat transfer and liquid cooling heat transfer. During operation, the heat from the power module is conducted through the encapsulation components to the heat dissipation substrate, and then to the liquid phase change working fluid within the substrate. The liquid phase change working fluid changes phase upon heating to a gaseous phase. Under pressure, the gaseous working fluid rises to the condensation section of the gravity heat pipe, where it exchanges heat with the flowing coolant within the cover. The gaseous working fluid condenses back into the liquid phase change working fluid, which then flows back to the surface of the heat dissipation substrate under gravity. The heat dissipation efficiency of this invention is more than 80% higher than existing liquid-cooled heat dissipation structures. Compared to assembled, independently fabricated heat pipe solutions, no additional assembly is required, resulting in a more reliable structure, simpler manufacturing process, and lower cost. It also avoids thermal resistance between the phase change working fluid, heat pipe encapsulation, and heat dissipation plate, improving heat dissipation efficiency by more than 30%. Furthermore, the outer envelope of the power module structure of this invention is consistent with existing standard module structures, allowing for direct replacement of existing structural solutions. Compared to assembled heat pipe heat dissipation solutions, this significantly reduces design costs and time. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the three-dimensional structure of the heat sink of the present invention.
[0020] Figure 2 This is a schematic diagram illustrating the structural principle of the heat sink of the present invention.
[0021] Figure 3 for Figure 2 A schematic diagram of the structural principle of the cross-section along the AA direction.
[0022] Figure 4 This is a schematic diagram illustrating the three-dimensional structure of the heat dissipation substrate and heat dissipation plate in the heat sink of the present invention.
[0023] Figure 5 This is a schematic diagram illustrating the structural principle of the heat dissipation substrate and heat dissipation plate in the heat sink of the present invention.
[0024] Figure 6 for Figure 5 A schematic diagram of the structural principle of the cross-section along the BB direction.
[0025] Figure 7 This is a schematic diagram of the three-dimensional structure of the cover in the radiator of the present invention.
[0026] Figure 8 This is a schematic diagram illustrating the structural principle of the cover in the radiator of the present invention.
[0027] Figure 9 for Figure 8 A schematic diagram of the cross-sectional structure along the CC direction.
[0028] Legend: 1. Heat dissipation substrate; 11. First groove; 12. Solid heat dissipation pin; 2. Heat dissipation plate; 21. Second groove; 22. Hollow heat dissipation pin; 23. Inner hole of pin; 3. Cover; 31. Coolant inlet; 32. Coolant outlet; 33. Third groove; 34. Cavity; 4. Chip; 5. Packaging component; 6. Input copper busbar; 7. Output copper busbar; a. Liquid phase change working medium. Detailed Implementation
[0029] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.
[0030] Example
[0031] like Figures 1 to 9 As shown, the present invention discloses a heat sink that utilizes a gravity heat pipe and a liquid cooling structure for coupled heat dissipation, comprising: a heat dissipation substrate 1, a heat dissipation plate 2, and a cover 3. The lower surface of the heat dissipation plate 2 is welded to the upper surface of the heat dissipation substrate 1, and the upper surface of the heat dissipation plate 2 is detachably connected to the cover 3 via a screw assembly. A power module is provided on the lower surface of the heat dissipation substrate 1, and the upper surface of the heat dissipation substrate 1 and the heat dissipation plate 2 together form a gravity heat pipe. The condensation section of the gravity heat pipe is encapsulated within the cover 3, and a flowing coolant is introduced into the cover 3 to immerse the condensation section of the gravity heat pipe in the coolant for coupled heat dissipation. To improve heat dissipation performance, both the heat dissipation substrate 1 and the heat dissipation plate 2 can be made of aluminum, and the coolant in the cover 3 can be a 50% ethylene glycol coolant.
[0032] In this embodiment, a first groove 11 is provided on the upper surface of the heat dissipation substrate 1, which is used to hold the liquid phase change working fluid a. Further, the first groove 11 is machined onto the upper surface of the heat dissipation substrate 1, and a plurality of solid heat dissipation fins 12 are provided at the bottom of the first groove 11 to enhance heat exchange between the liquid phase change working fluid a and the heat dissipation substrate 1. The solid heat dissipation fins 12 at the bottom of the first groove 11 enhance the heat exchange between the heat sink side of the heat dissipation substrate 1 and the liquid phase change working fluid; irregular vibrations during vehicle operation also significantly enhance this heat exchange. After absorbing heat, the liquid phase change working fluid a undergoes a phase change, utilizing its latent heat of phase change to maintain a low and uniform temperature on the heat sink side of the heat dissipation substrate 1, thereby improving the performance stability of the power module.
[0033] In this embodiment, the heat dissipation substrate 1, on which the power module is installed, and the heat dissipation plate 2 are welded together to form a gravity heat pipe. The upper surface of the heat dissipation substrate 1 and the heat dissipation plate 2 form a gravity heat pipe. At the same time, the condensation section of the gravity heat pipe is encapsulated in the cover 3, and coolant is introduced into the cover 3 so that the condensation section of the gravity heat pipe is immersed in the coolant. The two heat dissipation methods of phase change heat transfer and liquid cooling heat transfer are coupled in the heat sink, which has the advantages of compact structure, high structural strength and high heat dissipation performance.
[0034] like Figures 4 to 6 As shown, in this embodiment, the heat sink 2 is provided with a second groove 21, and the first groove 11 and the second groove 21 are interconnected, that is, the liquid phase change working fluid in the first groove 11 can enter the second groove 21 after undergoing a phase change due to heat. Further, the second groove 21 is provided with multiple hollow heat dissipation pins 22 with sealed tops, and each hollow heat dissipation pin 22 has an inner hole 23, which is interconnected with the second groove 21. The first groove 11, the second groove 21, and the inner hole 23 form a gravity heat pipe. The second groove 21 and the inner hole 23 serve as the condensation section of the gravity heat pipe. After the liquid phase change working fluid in the first groove 11 undergoes a phase change due to heat, it enters the second groove 21 and the inner hole 23 to achieve condensation of the phase change working fluid. It is understandable that when selecting a liquid phase change working medium, the phase change temperature is 75-80℃. The liquid phase change working medium can be liquid ammonia, R-21, R-11, R-113, acetone, or naphthalene, etc.
[0035] In this embodiment, the hollow heat dissipation fins 22 on the second groove 21 can be circular or square. The interior of the hollow heat dissipation fins 22 is hollowed out by machining while maintaining a certain wall thickness to form the inner hole 23 of the fin, and the inner hole 23 of the fin is connected to the second groove 21. The inner hole 23 of the fin and the second groove 21 together constitute the condensation section of the gravity heat pipe, serving as a space for strong heat exchange between the gaseous working fluid and the coolant in the cover 3. Specifically, after the liquid phase change working fluid in the first groove 11 is heated and transforms into a gaseous working fluid, it enters the second groove 21 and the inner hole 23 of the fin in sequence. After the gaseous working fluid condenses into a liquid working fluid, it drips into the first groove 11 under the action of gravity.
[0036] In this embodiment, the liquid phase change working medium a in the first groove 11 vaporizes upon heating and enters the second groove 21. It then condenses by exchanging heat with the coolant in the cover 3 through the inner holes 23 of the hollow heat dissipation pins 22. It can be understood that in this embodiment, because the internal pressure of the gravity heat pipe is relatively high during radiator operation, the hollow heat dissipation pins 22 need to maintain a certain wall thickness to prevent deformation under pressure. Furthermore, because the hollow heat dissipation pins 22 need to exchange heat with the coolant flowing in the cover 3, the wall thickness of the hollow heat dissipation pins 22 should not be too thick to avoid affecting heat exchange performance. During operation, the temperature of the inner wall of the hollow heat dissipation pins 22 is close to the coolant temperature but lower than the condensation temperature of the phase change working medium. Therefore, the phase change working medium rapidly condenses on the inner wall surface of the hollow heat dissipation pins 22 and then drips into the first groove 11 under gravity. It is understandable that this process can ensure that the temperature of the entire upper surface of the first groove 11 is never higher than the phase change temperature of the working fluid, and the temperature of the entire upper surface of the first groove 11 is highly uniform. Compared with the heat transfer efficiency of a solid metal heat-conducting structure of the same size, it is several times or even tens of times higher, which can greatly improve the heat exchange efficiency and uniformity of the heat dissipation structure.
[0037] In this embodiment, a through hole is provided at the top of any hollow heat dissipation fin 22 at the end of the second groove 21. A vacuum is created through this through hole to evacuate the gravity heat pipe formed by the first groove 11, the second groove 21, and the inner hole 23 of the fin. A liquid phase change working medium a is then injected into the gravity heat pipe through the through hole. Specifically, the gravity heat pipe is evacuated through the hollow heat dissipation fin 22 with the through hole at the top to achieve a preset vacuum level, and a corresponding volume of liquid phase change working medium is injected into the gravity heat pipe under vacuum conditions. A hydraulic clamp, in conjunction with a machined cutting tool, presses the through hole at the top of the hollow heat dissipation fin 22. Because a large amount of liquid phase change working medium in the first groove 11 vaporizes to generate steam during radiator operation, the pressure inside the gravity heat pipe increases sharply. Since the hollow heat dissipation fin 22 cannot withstand the high pressure inside the cavity of the heat dissipation mechanism by simply pressing and sealing it, spot welding is performed again at the pressed area after pressing to strengthen the seal. This completes the manufacturing process of the gravity heat pipe assembly. Since the heat dissipation substrate of this embodiment is basically the same as the traditional simple liquid cooling substrate structure, the power module can be packaged onto the heat dissipation substrate of this embodiment according to the traditional process, which is both simple and efficient.
[0038] like Figures 7 to 9 As shown, in this embodiment, the cover 3 includes a coolant inlet 31, a coolant outlet 32, and a cavity 34. The coolant inlet 31 and the coolant outlet 32 are located at opposite ends of the cavity 34. A second groove 21 with hollow heat dissipation fins 22 is encapsulated within the cavity 34. The coolant flows within the cavity 34 through the coolant inlet 31 and the coolant outlet 32, enabling strong heat exchange between the hollow heat dissipation fins 22 on the second groove 21 and the flowing coolant. This achieves heat exchange in the condensation section of the gravity heat pipe, allowing the phase change working fluid to undergo rapid and strong heat exchange, thus improving the operational stability of the power module.
[0039] Furthermore, the cover 3 is provided with a third groove 33, and a sealing element is provided in the third groove 33 to achieve a sealed connection between the cover 3 and the upper surface of the heat sink 2. It can be understood that the sealing element provided in the third groove 33 can be a sealing ring made of rubber, silicone, or polytetrafluoroethylene.
[0040] In this embodiment, the power module includes a power chip 4, a packaging component 5, an input copper busbar 6, and an output copper busbar 7. The packaging component 5 is connected to the lower surface of the heat dissipation substrate 1, and the power chip 4 is mounted on the packaging component 5. The input copper busbar 6 and the output copper busbar 7 are located at opposite ends of the packaging component 5. The outer envelope of the power module structure in this embodiment is almost identical to the existing structure, and it can be directly replaced based on the existing structural solution. Compared with the assembled heat pipe heat dissipation solution, it greatly reduces the design cost and cycle.
[0041] In this embodiment, when the heat sink is working, the heat from the power chip 4 is conducted to the heat dissipation substrate 1 through the packaging component 5, and then to the liquid phase change working medium a in the first groove 11. The liquid phase change working medium a undergoes a phase change to a gaseous working medium when heated. The gaseous working medium rises to the second groove 21 of the heat sink 2 and the inner hole 23 of the hollow heat dissipation pin 22, which is the condensation section of the gravity heat pipe, under the influence of air pressure. Heat is exchanged between the pin fin wall and the flowing coolant in the cover 3, realizing the condensation of the gaseous working medium into a liquid phase change working medium. The liquid phase change working medium flows back to the surface of the heat sink substrate 1 under the influence of gravity. The heat dissipation efficiency of the heat sink in this embodiment is improved by more than 80% compared with the existing liquid cooling heat dissipation structure. Compared with the assembled independent processing heat pipe solution, no additional assembly operation is required, the structural strength is more reliable, the process is simpler, the cost is lower, and the thermal resistance between the phase change working medium, heat pipe packaging and heat sink is avoided, and the heat dissipation efficiency is improved by more than 30%.
[0042] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.
Claims
1. A heat sink that utilizes a gravity heat pipe and a liquid cooling structure for coupled heat dissipation, characterized in that, include: The heat dissipation substrate (1), heat dissipation plate (2), and cover (3) are provided. The lower and upper surfaces of the heat dissipation plate (2) are connected to the upper surface of the heat dissipation substrate (1) and the cover (3) respectively. A power module is provided on the lower surface of the heat dissipation substrate (1). The upper surface of the heat dissipation substrate (1) and the heat dissipation plate (2) form a gravity heat pipe. A first groove (11) is provided on the upper surface of the heat dissipation substrate (1), which is used to hold a liquid phase change working fluid. A second groove (21) is provided on the heat dissipation plate (2), and the first groove (11) and the second groove (21) are connected. Multiple hollow heat dissipation fins (22) are provided on the second groove (21). The hollow heat dissipation fin (22) is provided with a fin inner hole (23), which is connected to the second groove (21); the first groove (11), the second groove (21) and the fin inner hole (23) form a gravity heat pipe, and the second groove (21) and the fin inner hole (23) serve as the condensation section of the gravity heat pipe. The liquid phase change working medium in the first groove (11) is heated and then changes to a gas phase working medium before entering the second groove (21) and the fin inner hole (23) to achieve the condensation of the phase change working medium; the condensation section of the gravity heat pipe is encapsulated in the cover (3), and a flowing coolant is introduced into the cover (3) to achieve the immersion of the condensation section of the gravity heat pipe in the coolant.
2. The heat sink according to claim 1, which utilizes a gravity heat pipe and a liquid cooling structure for coupled heat dissipation, is characterized in that... The bottom of the first groove (11) is provided with a plurality of solid heat dissipation pins (12), which are used to enhance the heat exchange between the liquid phase change working fluid and the heat dissipation substrate (1).
3. The heat sink according to claim 1, which utilizes a gravity heat pipe and a liquid cooling structure for coupled heat dissipation, is characterized in that... A through hole is set on the top of any hollow heat dissipation fin (22) located at the end of the second groove (21). The gravity heat pipe formed by the first groove (11), the second groove (21) and the inner hole (23) of the fin is evacuated through the through hole, and a liquid phase change working medium is injected into the gravity heat pipe through the through hole.
4. The heat sink according to claim 1, which utilizes a gravity heat pipe and a liquid cooling structure to achieve coupled heat dissipation, is characterized in that, The cover (3) includes a coolant inlet (31), a coolant outlet (32), and a cavity (34), and the condensation section of the gravity heat pipe is encapsulated in the cavity (34).
5. The heat sink according to claim 4, which utilizes a gravity heat pipe and a liquid cooling structure for coupled heat dissipation, is characterized in that... The cover (3) is provided with a third groove (33), and a sealing element is provided in the third groove (33) to achieve a sealed connection between the cover (3) and the upper surface of the heat sink (2).
6. The heat sink that utilizes a gravity heat pipe and a liquid cooling structure to achieve coupled heat dissipation according to any one of claims 1 to 5, characterized in that, The power module includes a power chip (4), a packaging component (5), an input copper busbar (6), and an output copper busbar (7). The packaging component (5) is connected to the lower surface of the heat dissipation substrate (1). The power chip (4) is provided on the packaging component (5). The input copper busbar (6) and the output copper busbar (7) are located at opposite ends of the packaging component (5).
7. The heat sink that utilizes a gravity heat pipe and a liquid cooling structure to achieve coupled heat dissipation according to any one of claims 1 to 5, characterized in that, The lower surface of the heat sink (2) is welded to the upper surface of the heat sink substrate (1).
8. The heat sink that utilizes a gravity heat pipe and a liquid cooling structure to achieve coupled heat dissipation according to any one of claims 1 to 5, characterized in that, The upper surface of the heat sink (2) is detachably connected to the cover (3).