Thermal management system and method for light-weight oil-electricity hybrid power aircraft

Abstract

The invention belongs to the technical field of helicopter environmental control / thermal management, and discloses a thermal management system and method for a light-weight oil-electricity hybrid power aircraft, the thermal management system comprises liquid cooling circulation, evaporation circulation, high-temperature PAO circulation and fuel circulation, and thermal management of a plurality of heat dissipation components is achieved through one set of liquid cooling circulation and PAO circulation. The problem that heat management of high-power equipment of an aircraft is difficult is solved, and comprehensive management of heat is achieved through the lightweight and integrated design.

Description

Technical Field

[0001] This invention belongs to the field of helicopter environmental control / thermal management technology, and discloses a thermal management system configuration and control method for a lightweight hybrid electric vertical takeoff and landing aircraft. Background Technology

[0002] Hybrid electric vertical takeoff and landing (VTOL) aircraft benefit from battery power replenishment, resulting in low fuel consumption, long range, and the elimination of complex transmission systems, making them promising for widespread applications. However, they have numerous heat sources, including the engine, generator and its controller, power battery, drive motor, and power conversion device, generating significant heat with large peak-to-average variations. For example, during takeoff and landing, the power battery and engine provide power simultaneously, resulting in the highest instantaneous heat output from the battery and power conversion device. During level flight, the battery is charging, and the heat output is only a fraction of that during takeoff and landing, or even nonexistent when fully charged. Designing each component based on its maximum instantaneous heat output would be impractical due to significant limitations in size and weight.

[0003] On the other hand, the power battery has a very limited thermal boundary (15°C-35°C) for optimal operation; exceeding this temperature can significantly alter the thermal characteristics of the battery system and degrade its performance. Designing a thermal management system that meets the requirements while minimizing additional costs is a key issue that needs to be addressed in the development of hybrid-powered vertical takeoff and landing (VTOL) aircraft. Summary of the Invention

[0004] Purpose of the invention: To address the challenges of thermal management for high-power equipment in aircraft, this invention provides a lightweight hybrid electric vehicle thermal management system and method. It comprehensively manages the thermal of the engine, generator, generator controller, power battery, and power conversion device, achieving integrated heat management through lightweight and integrated design.

[0005] To address the above-mentioned technical issues, the present invention provides the following technical solution: In a first aspect, the present invention provides a thermal management system for a lightweight hybrid electric aircraft, comprising: The liquid cooling cycle exchanges heat with the battery pack through the battery cold plate group, with the power conversion device through the power conversion device cold plate group, and with the generator controller through the generator controller cold plate. The evaporation cycle is connected to the liquid cooling cycle through a coolant-refrigerant heat exchanger and exchanges heat, transferring the heat from the battery, power conversion device, and generator controller in the liquid cooling cycle to the fuel cycle or the ambient atmosphere through the refrigerant. The fuel cycle is connected to the evaporation cycle through a refrigerant-fuel heat exchanger and exchanges heat, absorbing the heat from the evaporation cycle and transferring it to the fuel tank. In the PAO cycle, PAO oil and the coolant in the liquid cooling cycle are connected and exchange heat through a heat recovery heat exchanger. Heat exchange also occurs through the lubricating oil module inside the engine-generator, the engine gearbox, and the generator. Finally, heat exchange occurs with the ambient atmosphere through the air-cooled radiator.

[0006] As a further technical solution of the present invention: the battery cold plate group and the power conversion device cold plate group are connected in parallel network, and are sequentially connected to the temperature regulating valve, the generator controller cold plate, the expansion tank and the booster pump through liquid cooling pipelines; A first sensor group is installed at the inlet of the battery cold plate group and the power conversion device cold plate group; A second sensor group is installed at the cold plate outlet of the generator controller.

[0007] As a further technical solution of the present invention: the a port and b port of the temperature regulating valve are respectively connected to the generator controller cold plate and the expansion tank. The flow ratio of the a port and the b port can be adjusted according to the outlet temperature fed back by the second sensor group, and the adjustment is controlled by the host computer.

[0008] As a further technical solution of the present invention: the outlet of the booster pump is divided into two paths, which are respectively connected to the first shut-off valve and the second shut-off valve; The outlet of the first shut-off valve is connected to the coolant-refrigerant heat exchanger and is used to control the flow of coolant into the coolant-refrigerant heat exchanger. The outlet of the coolant-refrigerant heat exchanger is connected to the third and fourth shut-off valves.

[0009] As a further technical solution of the present invention: the third shut-off valve and the fourth shut-off valve are respectively connected to the cold battery cold plate group and the power conversion device cold plate group, and are used to control the flow of coolant into the battery cold plate group and the power conversion device cold plate group; The second shut-off valve is connected to the heat recovery heat exchanger and controls the flow of coolant in the heat recovery heat exchanger. The outlet of the heat recovery heat exchanger is connected to the third and fourth shut-off valves.

[0010] As a further technical solution of the present invention: the air-cooled condenser, the refrigerant-fuel heat exchanger, the expansion valve, the coolant-refrigerant heat exchanger, and the compressor are connected in sequence through refrigerant pipelines; The second bypass valve is connected in parallel at both ends of the air-cooled condenser, and the first bypass valve is connected in parallel at both ends of the refrigerant-fuel heat exchanger.

[0011] As a further technical solution of the present invention: the fuel pump, the refrigerant-fuel heat exchanger, and the fuel tank are connected in sequence via fuel pipelines. A third sensor group is installed on the fuel line at the inlet of the refrigerant-fuel heat exchanger.

[0012] As a further technical solution of the present invention: the PAO oil tank outlet is connected in sequence to an oil pump and a temperature control valve; The air-cooled radiator is arranged in the circuit after the temperature control valve. Part of the PAO oil inside the temperature control valve enters the air-cooled radiator, and the other part flows directly out of the temperature control valve. Its opening ratio is adjusted according to the temperature feedback from the fourth sensor group. The third bypass valve is connected in parallel with the heat recovery heat exchanger. Its inlet end is connected to the outlet end of the temperature control valve, and its outlet end is connected to the lubricating oil module inside the engine-generator. The outlet of the internal lubricating oil module of the engine-generator is connected to the PAO oil tank; A fourth sensor group is installed at the outlet of the lubricating oil module inside the engine-generator; The air-cooled radiator and the air-cooled condenser of the evaporation cycle are set in the same air duct, with the air-cooled condenser located upwind of the air-cooled radiator.

[0013] Secondly, the present invention provides a thermal management method for a lightweight hybrid electric vehicle, comprising the following steps: Before takeoff, or when charging at an ambient temperature above 40°C, the ground charging device is activated, and the evaporative cycle compressor and the cryogenic liquid cooling system work to pre-cool the battery and transfer the battery heat to the ambient atmosphere. Before takeoff, when the battery needs to be heated in cold weather, the evaporative cycle compressor and the liquid cooling system work, the high-temperature PAO cycle works, and the liquid cooling system absorbs the heat from the engine-generator lubricating oil module to heat the battery. During takeoff, the evaporative cooling cycle, liquid cooling cycle, and fuel cycle operate to cool the power conversion device and generator controller, transferring heat to the fuel tank and ambient atmosphere; the PAO cycle operates to cool the engine and generator, transferring heat to the ambient atmosphere. During level flight, when the temperature is above -20°C, the evaporative cooling cycle and liquid cooling cycle operate to cool the battery and generator controller and transfer heat to the ambient atmosphere; the PAO cycle operates to cool the engine and generator and transfer heat to the ambient atmosphere. During level flight, when the temperature is below -20°C, the evaporative cooling cycle, liquid cooling cycle, and fuel cycle operate to cool the battery and generator controller and transfer heat to the fuel tank; the PAO cycle operates to cool the engine and generator and transfer heat to the ambient atmosphere. During the descent phase, the operating mode is the same as during the takeoff phase, with the evaporative cycle, liquid cooling cycle, and fuel cycle operating to cool the power conversion device and generator controller, and transfer heat to the fuel tank and ambient atmosphere; the PAO cycle operates to cool the engine and generator, and transfer heat to the ambient atmosphere. In the event of an engine failure, the aircraft needs to land as quickly as possible. The liquid cooling cycle, evaporation cycle, and fuel cycle will operate to cool the power conversion device and battery, and transfer heat to the fuel tank and the ambient atmosphere; the PAO cycle will be shut down.

[0014] As a further technical solution of the present invention: the temperature inside the battery after pre-cooling should be such that the final average temperature inside the battery after takeoff is not higher than the normal operating limit of the battery. In cold climates, the internal temperature of the battery after heating should not be lower than the minimum temperature at which the battery can normally discharge at high rates. During the level flight phase, the internal temperature of the battery after cooling should ensure that the final average internal temperature of the battery after landing does not exceed the normal operating limit of the battery, and that the final average internal temperature of the battery after emergency landing does not exceed the battery safety limit.

[0015] In summary, the beneficial effects of the present invention are as follows: 1) This invention comprehensively considers the heat sources such as engine generators, generator controllers, batteries, and power conversion devices, as well as the heat management needs and working states of multiple heat management objects such as power systems, fuel systems, and electrical systems. It achieves heat management of multiple heat dissipation components through a set of liquid cooling cycles and PAO cycles, effectively solving the problems of multiple and dispersed distributed heat management loops, large heat dissipation design, many components, and high cost.

[0016] 2) This invention utilizes the cold storage and pre-cooling effects brought about by the evaporation cycle system to solve the problem of excessive differences in the peak average heat generation of the power battery, power conversion device and controller, and the designed heat dissipation power is much smaller than the sum of multiple thermal management objects.

[0017] 3) During takeoff and landing, the large amount of fuel in the fuel tank acts as a heat sink to absorb the instantaneous peak heat generated by the battery. During level flight, only the atmosphere acts as a heat sink, avoiding the fuel continuously absorbing heat and causing excessively high temperatures. In cold seasons, the dissipated heat can be used to warm the fuel, helping to solve the problem of low combustion efficiency due to excessively low fuel temperature.

[0018] 4) When the battery needs to be heated in winter, the heat from the engine, generator and controller is recycled to heat the power battery, realizing the recycling of waste heat.

[0019] 5) Fully utilize the components of the airborne thermal management system for battery pre-cooling and heating, eliminating the need for ground support equipment and reducing the maintenance and support pressure on ground stations.

[0020] 6) The air-cooled radiator and the air-cooled condenser share the same fan and air duct, reducing component weight, power consumption, and air resistance.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the thermal management system architecture for a hybrid electric vertical takeoff and landing aircraft according to the present invention; Figure 2 This is a schematic diagram of the pre-cooling mode of the pre-flight thermal management system of the present invention; Figure 3 This is a schematic diagram of the cooling mode of the thermal management system during takeoff in this invention; Figure 4 This is a schematic diagram of the cooling mode of the thermal management system during the level flight phase of the present invention. Figure 5 This is a schematic diagram of the cooling mode of the thermal management system in the event of an engine failure according to the present invention; Figure 6 This is a schematic diagram of the pre-flight thermal management system heating mode of the present invention.

[0023] The attached diagram is labeled as follows: Circulation 1 is the liquid cooling cycle, the circulating medium is coolant; 11—booster pump; 12—first shut-off valve; 13—coolant-refrigerant heat exchanger; 14—flow sensor; 15—first sensor group; 16—battery cold plate group; 17—power conversion device cold plate group; 18—regulating valve; 110—generator controller cold plate; 111—second sensor group; 112—expansion tank; 113—second shut-off valve; 114—heat recovery heat exchanger; 115—third shut-off valve; 116—fourth shut-off valve. Cycle 2 is an evaporation cycle, with refrigerant as the circulating medium. 21—compressor, 22—air-cooled condenser, 23—refrigerant-fuel heat exchanger, 24—first bypass valve, 25—expansion valve, 26—second bypass valve; Cycle 3 is the fuel cycle, 31—fuel pump, 32—fuel tank, 33—third sensor group; Cycle 4 is the PAO cycle, 41—temperature control valve, 42—cooling fan, 43—air-cooled radiator, 44—third bypass valve, 45—engine generator internal lubricating oil module, 46—oil pump, 47—PAO oil tank, 48—fourth sensor group. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described in more detail below with reference to the accompanying drawings.

[0025] In the accompanying drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present invention.

[0026] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] The following is in conjunction with the appendix Figure 1-6 The embodiments of the present invention will be described in detail below.

[0028] Example 1 This invention discloses a thermal management system for a lightweight hybrid electric vehicle, comprising a liquid cooling cycle 1, an evaporation cycle 2, a high-temperature PAO cycle 3, and a fuel cycle 4.

[0029] The liquid cooling cycle 1 includes a booster pump 11, a first shut-off valve 12, a coolant-refrigerant heat exchanger 13, a flow sensor 14, a first sensor group 15, a battery cold plate group 16, a power conversion device cold plate group 17, a temperature regulating valve 18, a generator controller cold plate 110, a first bypass valve 19, a second sensor group 111, an expansion tank 112, a second shut-off valve 113, a heat recovery heat exchanger 114, liquid cooling pipelines and accessories.

[0030] The liquid cooling cycle exchanges heat with the battery pack through the battery cold plate group 16, exchanges heat with the power conversion device through the power conversion device cold plate group 17, and exchanges heat with the generator controller through the generator controller cold plate 110.

[0031] The battery cold plate assembly 16 and the power conversion device cold plate assembly 17 are connected in parallel, and are sequentially connected to the temperature regulating valve 18, the generator controller cold plate 110, the expansion tank 112, and the booster pump 11 through liquid cooling pipelines. A first sensor group 15 is installed at the inlet of the battery cold plate assembly 16 and the power conversion device cold plate assembly 17; a second sensor group 111 is installed at the outlet of the generator controller cold plate 110.

[0032] Port a and port b of the temperature regulating valve 18 are connected to the generator controller cold plate 110 and expansion tank 112, respectively. The flow ratio of port a and port b can be adjusted according to the outlet temperature fed back by the second sensor group 111, and the adjustment is controlled by the host computer.

[0033] The expansion tank 112 is used to balance the pressure of the coolant and can be located at any node of the main pipeline of the liquid cooling cycle.

[0034] The booster pump 11 has two outlets, connected to a first shut-off valve 12 and a second shut-off valve 113, respectively. The outlet of the first shut-off valve 12 is connected to the coolant-refrigerant heat exchanger 13 to control the flow of coolant into the heat exchanger 13. The outlet of the coolant-refrigerant heat exchanger 13 is connected to a third shut-off valve 115 and a fourth shut-off valve 116.

[0035] The third shut-off valve 115 and the fourth shut-off valve 116 are respectively connected to the cold battery cold plate group 16 and the power conversion device cold plate group 17, and are used to control the flow of coolant into the battery cold plate group 16 and the power conversion device cold plate group 17.

[0036] The flow sensor 14 is not suitable to be located upstream of the booster pump 11, but is generally located upstream of the battery cold plate group 16 and the power conversion device cold plate group 17.

[0037] The second shut-off valve 113 is connected to the heat recovery heat exchanger 114 and controls the flow of coolant in the heat recovery heat exchanger 114. The outlet of the heat recovery heat exchanger 114 is connected to the third shut-off valve 115 and the fourth shut-off valve 116.

[0038] The circulating medium for liquid cooling is coolant, which can be a mixture of water and ethylene glycol, such as AF65 coolant.

[0039] Evaporation cycle 2 includes a compressor 21, an air-cooled condenser 22, a refrigerant-fuel heat exchanger 23, a second bypass valve 24, an expansion valve 25, and refrigerant piping accessories. The air-cooled condenser 22, refrigerant-fuel heat exchanger 23, expansion valve 25, coolant-refrigerant heat exchanger 13, and compressor 21 are connected sequentially via refrigerant piping. The second bypass valve 26 is connected in parallel across the air-cooled condenser 22, and the first bypass valve 2 is connected in parallel across the refrigerant-fuel heat exchanger 23.

[0040] The evaporation cycle and the liquid cooling cycle are connected and exchange heat through a coolant-refrigerant heat exchanger 13. The circulating medium of the evaporation cycle is a refrigerant, such as R134a.

[0041] The fuel circulation system 3 includes a fuel pump 31, a fuel tank 32, a third sensor group 33, and fuel line accessories. The fuel pump 31, the refrigerant-fuel heat exchanger 23, and the fuel tank 32 are connected sequentially via fuel lines. The third sensor group 33 is installed on the fuel line at the inlet of the refrigerant-fuel heat exchanger 23.

[0042] The evaporation cycle and the fuel cycle are connected and exchange heat through a refrigerant-fuel heat exchanger 23. The circulating medium in the fuel cycle is the fuel used on the aircraft.

[0043] PAO cycle 4 includes a high-temperature PAO temperature control valve 41, a cooling fan 42, an air-cooled radiator 43, a third bypass valve 44, an internal lubricating oil module 45 for the engine-generator, an oil pump 46, a PAO oil tank 47, a fourth sensor group 48, and piping. The outlet of the PAO oil tank 47 is connected sequentially to the oil pump 46 and the temperature control valve 41. The air-cooled radiator 43 is located in the loop after the temperature control valve 41. Part of the PAO oil inside the temperature control valve 41 enters the air-cooled radiator 43, and the other part flows directly out of the temperature control valve 41. Its opening ratio is adjusted according to the temperature feedback from the fourth sensor group 48. The third bypass valve 44 is connected in parallel with the heat recovery heat exchanger 114. Its inlet is connected to the outlet of the temperature control valve 41, and its outlet is connected to the internal lubricating oil module 45 for the engine-generator. The outlet of the internal lubricating oil module 45 for the engine-generator is connected to the PAO oil tank 47. The fourth sensor group 48 is installed at the outlet of the internal lubricating oil module 45 for the engine-generator.

[0044] The air-cooled radiator 43 and the air-cooled condenser 22 of the evaporator cycle are located in the same air duct, with the air-cooled condenser 22 positioned upwind of the air-cooled radiator 43. The PAO oil in the PAO cycle and the coolant in the liquid-cooled cycle are connected and exchange heat through the heat recovery heat exchanger 114. Heat exchange also occurs through the engine-generator internal lubricating oil module 45 with the engine gearbox and generator, and through the air-cooled radiator 43 with the ambient atmosphere. The circulating medium in the PAO cycle is PAO synthetic oil.

[0045] In the above technical solution, the liquid cooling cycle 1, the evaporation cycle 2, the high-temperature PAO cycle 3, and the fuel cycle 4 also include a control section.

[0046] Example 2 This invention discloses a thermal management method for a lightweight hybrid electric vehicle, comprising the following steps: like Figure 2As shown, before takeoff, or when charging at an ambient temperature higher than 40°C, the ground charging device is activated, the evaporative cycle compressor and the cryogenic liquid cooling system operate, the first shut-off valve 12 and the third shut-off valve 115 are open, the second shut-off valve 113 and the fourth shut-off valve 116 are closed, the first bypass valve 24 is open, and the second bypass valve 26 is closed. The fuel circulation pump 31 and the PAO fuel circulation pump 41 are shut off, and the fan 42 is turned on. In the evaporative cycle loop, the opening of the electronic expansion valve 25 is adjusted to maintain the evaporative temperature of the refrigeration system at a low temperature, such as around 5°C. The refrigerant exchanges heat with the coolant in the liquid cooling cycle in the coolant-refrigerant heat exchanger 13, carrying away the heat from the coolant at a higher temperature (first temperature). Under the forced convection of the fan 42, the refrigerant heat is dissipated into the ambient atmosphere in the air-cooled condenser 22. After being cooled in the coolant-refrigerant heat exchanger 13, the coolant in the liquid cooling cycle enters the battery cold plate assembly 16 under the action of the booster pump 11 to absorb the heat generated by the battery, causing its temperature to rise. It then enters the expansion tank and flows back into the coolant-refrigerant heat exchanger 13 to be cooled again, completing one cycle. Ultimately, the average internal temperature of the battery is cooled to below the ambient air temperature, referred to as the first temperature. The first temperature after pre-cooling should be determined after analysis and evaluation based on the total heat generated by the power battery during takeoff. During takeoff, the battery, power conversion device, and generator controller dissipate heat at high power, causing the internal temperature of the battery to rise rapidly. The first temperature should ensure that the final average internal temperature of the battery after takeoff (referred to as the second temperature) does not exceed the normal operating limit of the battery.

[0047] like Figure 3As shown, during takeoff, the battery and power conversion device dissipate heat at high power. The evaporative cooling system, liquid cooling system, fuel circulation system, and high-temperature PAO circulation system operate. The first shut-off valve 12 and the fourth shut-off valve 116 are open, while the second shut-off valve 113 and the third shut-off valve 115 are closed. The first bypass valve 24 and the second bypass valve 26 are closed. The fuel circulation pump 31 and the high-temperature PAO fuel circulation pump 46 are shut off, and the fan 42 is turned on. In the evaporative cooling loop, the opening of the electronic expansion valve 25 is adjusted to maintain the evaporative temperature of the cooling system at a relatively high temperature, such as around 40°C. In the coolant-refrigerant heat exchanger 13, the refrigerant exchanges heat with the coolant in the liquid-cooled circulation, carrying away the heat from the coolant at a higher temperature (first temperature). Under the forced convection of the fan 42, some of the heat is dissipated to the ambient atmosphere in the air-cooled condenser 22. Then, it enters the refrigerant-fuel heat exchanger 23, where the refrigerant exchanges heat with the fuel, transferring another part of the heat to the fuel. Then, it enters the expansion valve 25 for throttling and expansion, and then enters the coolant-refrigerant heat exchanger 13, where the refrigerant absorbs the heat from the coolant in the liquid-cooled circulation. The coolant in the liquid-cooled circulation is cooled in the coolant-refrigerant heat exchanger 13, and its temperature decreases. Under the action of the booster pump 11, it enters the power conversion device cold plate assembly 17, absorbs the heat generated by the power conversion device, and its temperature rises. Then it flows into the temperature control valve 18. The temperature control valve adjusts the coolant flow rate at outlet a and outlet b based on the temperature feedback from the second sensor assembly 111. After that, the coolant at outlet a flows into the generator controller cold plate assembly 110, absorbs the heat generated by the generator controller, and its temperature rises again. It then merges with the coolant at outlet b and enters the expansion tank. Under the action of the booster pump 11, it flows back into the coolant-refrigerant heat exchanger 13 to be cooled, completing one cycle. During takeoff, the heat instantaneously dissipated by the power conversion device and generator controller is carried away by the liquid-cooled circulation coolant. The heat dissipated by the battery is absorbed by its internal cells, and the battery cell temperature rises, which is called the second temperature.

[0048] During the PAO cycle, the oil pump 46 operates, the third bypass valve 44 opens, and the PAO oil enters the temperature control valve 41 under the action of the oil pump 46. The temperature control valve 42 delivers all the PAO oil to the air-cooled radiator 43. Under the forced convection of the fan 42, the PAO heat is dissipated to the ambient atmosphere in the air-cooled radiator 43, and the PAO oil temperature decreases. It then enters the lubricating oil module 45 inside the engine generator through the third bypass valve 44 to absorb the heat generated by the engine and generator, and then enters the high-temperature PAO oil tank 47 to complete one cycle.

[0049] like Figure 4As shown, during the level flight phase, the generator controller, battery, and power conversion device generate almost no heat. Only the generator controller, engine, and generator generate heat, operating in evaporative cooling cycle, liquid cooling cycle, and high-temperature PAO cycle.

[0050] When the ambient temperature is above -20°C, the first bypass valve 24 opens, the second bypass valve 26 closes, and the fuel cycle is shut off. In the liquid-cooled cycle, the first shut-off valve 12 and the third shut-off valve 115 open, while the second shut-off valve 113 and the fourth shut-off valve 116 close. In the high-temperature PAO cycle, the third bypass valve 44 opens. In the evaporator cycle, the refrigerant exchanges heat with the coolant in the liquid-cooled cycle in the coolant-refrigerant heat exchanger 13, carrying away the heat from the higher-temperature (second temperature) coolant. Under the forced convection of the fan 42, the refrigerant heat is dissipated to the ambient atmosphere in the air-cooled condenser 22. After being cooled in the coolant-refrigerant heat exchanger 13, the liquid-cooled system's coolant, under the action of the booster pump 11, enters the battery cold plate assembly 16 to absorb the heat generated by the battery. Then, through the temperature control valve 18, it enters the generator controller cold plate 110 to absorb the heat from the generator controller. It then enters the expansion tank and, under the action of the booster pump 11, flows back into the coolant-refrigerant heat exchanger 13 to be cooled again, completing one cycle. During level flight, the liquid-cooled system continuously removes heat from the battery and generator controller, causing the internal temperature of the battery to gradually decrease.

[0051] During the high-temperature PAO cycle, the oil pump 46 operates, the third bypass valve 44 opens, and the PAO oil enters the temperature control valve 41 under the action of the oil pump 46. The temperature control valve 42 delivers all the PAO oil to the air-cooled radiator 43. Under the forced convection of the fan 42, the heat of the PAO oil is dissipated to the ambient atmosphere in the air-cooled radiator 43, and the PAO oil temperature decreases. It then enters the lubricating oil module 45 inside the engine generator through the third bypass valve 44 to absorb the heat generated by the engine and generator, and then enters the high-temperature PAO oil tank 47 to complete one cycle.

[0052] When the ambient temperature is below -20℃, to avoid excessive heat exchange in the air-cooled condenser 22, the second bypass valve 26 is opened and the first bypass valve 24 is closed. The refrigerant bypasses the air-cooled condenser 22 and only passes through the refrigerant-fuel heat exchanger 23. Fuel circulation is activated, the fuel pump 31 operates, and the fuel absorbs heat from the refrigerant in the refrigerant-fuel heat exchanger 23 and returns to the fuel tank, causing the temperature inside the fuel tank to gradually rise.

[0053] The normal descent phase operates in the same mode as the takeoff phase. During descent, the battery, power conversion unit, and generator controller dissipate heat at high power, causing the coolant temperature to rise rapidly. During level flight, the control module controls the battery's internal temperature to decrease to below the third temperature. The third temperature should ensure that the final average internal temperature of the battery after landing (referred to as the fourth temperature) does not exceed the battery's normal operating limit.

[0054] In the event of engine failure, the aircraft needs to land as quickly as possible; during the descent phase, the heat output of the battery and power conversion device reaches its maximum value across all profiles. For example... Figure 5 As shown, at this time, the high-temperature PAO cycle is shut down, and the liquid cooling cycle, evaporation cycle, and fuel cycle are operating. In the liquid cooling cycle, temperature control valve 18 delivers all coolant to outlet b, and the generator controller cold plate 110 is bypassed. In the evaporation cycle, the first bypass valve 24 and the second bypass valve 26 are closed. The refrigerant absorbs heat from the coolant in the coolant-refrigerant heat exchanger 13, dissipates some of the heat to the ambient atmosphere through the air-cooled condenser 22, and transfers the remaining heat to the fuel tank through the refrigerant-fuel heat exchanger 23. The third temperature should ensure that the final average internal temperature of the battery after landing (referred to as the fifth temperature) does not exceed the battery safety limit.

[0055] In cold climates, the battery temperature is too low, and the power battery needs to be warmed up before takeoff. Figure 6 As shown, the evaporation cycle and fuel cycle are closed. After the engine starts, the liquid cooling cycle and the high-temperature PAO cycle operate. The first shut-off valve 12 of the liquid cooling cycle is closed, and the second shut-off valve 113 is open. The PAO cycle bypass valve 44 is closed. The PAO oil absorbs heat from the engine and generator in the engine-generator lubricating oil module, and its temperature rises. Under the action of the oil pump 46, it enters the temperature control valve. The PAO oil bypasses the air-cooled radiator 43 and directly enters the heat recovery heat exchanger 114. In the heat recovery heat exchanger 114, heat is transferred to the liquid cooling system coolant. After absorbing heat, the coolant in the liquid cooling cycle enters the battery cold plate assembly 16, transferring heat to the battery, and the battery temperature gradually rises. The internal temperature of the battery after heating is completed is called the sixth temperature, which should not be lower than the minimum temperature for normal high-rate discharge of the battery.

[0056] Thus, the objective of this invention has been achieved.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermal management system for a lightweight hybrid electric aircraft, characterized in that, include: The liquid cooling cycle exchanges heat with the battery pack through the battery cold plate group, with the power conversion device through the power conversion device cold plate group, and with the generator controller through the generator controller cold plate. The evaporation cycle is connected to the liquid cooling cycle through a coolant-refrigerant heat exchanger and exchanges heat, transferring the heat from the battery, power conversion device, and generator controller in the liquid cooling cycle to the fuel cycle or the ambient atmosphere through the refrigerant. The fuel cycle is connected to the evaporation cycle through a refrigerant-fuel heat exchanger and exchanges heat, absorbing the heat from the evaporation cycle and transferring it to the fuel tank. In the PAO cycle, PAO oil and the coolant in the liquid cooling cycle are connected and exchange heat through a heat recovery heat exchanger. Heat exchange also occurs through the lubricating oil module inside the engine-generator, the engine gearbox, and the generator. Finally, heat exchange occurs with the ambient atmosphere through the air-cooled radiator.

2. The thermal management system for the lightweight hybrid electric aircraft according to claim 1, characterized in that, The battery cold plate assembly is connected to the power conversion device cold plate assembly in parallel network, and is sequentially connected to the temperature regulating valve, generator controller cold plate, expansion tank and booster pump through liquid cooling pipelines. A first sensor group is installed at the inlet of the battery cold plate group and the power conversion device cold plate group; A second sensor group is installed at the cold plate outlet of the generator controller.

3. The thermal management system for the lightweight hybrid electric aircraft according to claim 2, characterized in that, The temperature regulating valve's ports a and b are connected to the generator controller's cold plate and expansion tank, respectively. The flow ratio between ports a and b can be adjusted based on the outlet temperature fed back by the second sensor group, and this adjustment is controlled by the host computer.

4. The thermal management system for the lightweight hybrid electric aircraft according to claim 3, characterized in that, The booster pump outlet is divided into two paths, which are respectively connected to the first shut-off valve and the second shut-off valve; The outlet of the first shut-off valve is connected to the coolant-refrigerant heat exchanger and is used to control the flow of coolant into the coolant-refrigerant heat exchanger. The outlet of the coolant-refrigerant heat exchanger is connected to the third and fourth shut-off valves.

5. The thermal management system of the lightweight hybrid electric aircraft according to claim 4, characterized in that, The third and fourth shut-off valves are connected to the cold battery cold plate group and the power conversion device cold plate group, respectively, and are used to control the flow of coolant into the cold battery cold plate group and the power conversion device cold plate group. The second shut-off valve is connected to the heat recovery heat exchanger and controls the flow of coolant in the heat recovery heat exchanger. The outlet of the heat recovery heat exchanger is connected to the third and fourth shut-off valves.

6. The thermal management system for the lightweight hybrid electric aircraft according to claim 5, characterized in that, The air-cooled condenser, refrigerant-fuel heat exchanger, expansion valve, coolant-refrigerant heat exchanger, and compressor are connected in sequence through refrigerant pipelines; The second bypass valve is connected in parallel at both ends of the air-cooled condenser, and the first bypass valve is connected in parallel at both ends of the refrigerant-fuel heat exchanger.

7. The thermal management system for the lightweight hybrid electric aircraft according to claim 6, characterized in that, The fuel pump, refrigerant-fuel heat exchanger, and fuel tank are connected in sequence via fuel lines. A third sensor group is installed on the fuel line at the inlet of the refrigerant-fuel heat exchanger.

8. The thermal management system for the lightweight hybrid electric aircraft according to claim 7, characterized in that, The PAO oil tank outlet is connected in sequence to the oil pump and the temperature control valve; The air-cooled radiator is arranged in the circuit after the temperature control valve. Part of the PAO oil inside the temperature control valve enters the air-cooled radiator, and the other part flows directly out of the temperature control valve. Its opening ratio is adjusted according to the temperature feedback from the fourth sensor group. The third bypass valve is connected in parallel with the heat recovery heat exchanger. Its inlet end is connected to the outlet end of the temperature control valve, and its outlet end is connected to the lubricating oil module inside the engine-generator. The outlet of the internal lubricating oil module of the engine-generator is connected to the PAO oil tank; A fourth sensor group is installed at the outlet of the lubricating oil module inside the engine-generator; The air-cooled radiator and the air-cooled condenser of the evaporation cycle are set in the same air duct, with the air-cooled condenser located upwind of the air-cooled radiator.

9. A thermal management method for a lightweight hybrid electric aircraft, characterized in that, Includes the following steps: Before takeoff, or when charging at an ambient temperature above 40°C, the ground charging device is activated, and the evaporative cycle compressor and the cryogenic liquid cooling system work to pre-cool the battery and transfer the battery heat to the ambient atmosphere. Before takeoff, when the battery needs to be heated in cold weather, the evaporative cycle compressor and the liquid cooling system work, the high-temperature PAO cycle works, and the liquid cooling system absorbs the heat from the engine-generator lubricating oil module to heat the battery. During takeoff, the evaporative cooling cycle, liquid cooling cycle, and fuel cycle operate to cool the power conversion device and generator controller, transferring heat to the fuel tank and ambient atmosphere; the PAO cycle operates to cool the engine and generator, transferring heat to the ambient atmosphere. During level flight, when the temperature is above -20°C, the evaporative cooling cycle and liquid cooling cycle operate to cool the battery and generator controller and transfer heat to the ambient atmosphere; the PAO cycle operates to cool the engine and generator and transfer heat to the ambient atmosphere. During level flight, when the temperature is below -20°C, the evaporative cooling cycle, liquid cooling cycle, and fuel cycle operate to cool the battery and generator controller and transfer heat to the fuel tank; the PAO cycle operates to cool the engine and generator and transfer heat to the ambient atmosphere. During the descent phase, the operating mode is the same as during the takeoff phase, with the evaporative cycle, liquid cooling cycle, and fuel cycle operating to cool the power conversion device and generator controller, and transfer heat to the fuel tank and ambient atmosphere; the PAO cycle operates to cool the engine and generator, and transfer heat to the ambient atmosphere. When the engine fails, the aircraft needs to land as soon as possible. The liquid cooling cycle, evaporation cycle and fuel cycle work to cool the power conversion device and battery, and transfer heat to the fuel tank and the ambient atmosphere. PAO loop closed.

10. The thermal management method for a lightweight hybrid electric aircraft according to claim 9, characterized in that, After pre-cooling, the internal temperature of the battery should be such that the final average internal temperature of the battery after takeoff does not exceed the normal operating limit of the battery. In cold climates, the internal temperature of the battery after heating should not be lower than the minimum temperature at which the battery can normally discharge at high rates. During the level flight phase, the internal temperature of the battery after cooling should ensure that the final average internal temperature of the battery after landing does not exceed the normal operating limit of the battery, and that the final average internal temperature of the battery after emergency landing does not exceed the battery safety limit.

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