Battery thermal management system and method for a luggage tow vehicle

Abstract

A battery thermal management system and method for luggage towing vehicle, the system comprises a battery pack shell, a battery array, a liquid phase cooling medium, a solid-liquid two-phase cooling medium, a separation net, a cooling circulation unit and a control system. The liquid phase cooling medium fills the lower part of the shell to immerse the battery array; the solid-liquid two-phase cooling medium fills the upper part, is composed of an insulating liquid phase carrier and phase change material microcapsules, and is separated from the liquid phase medium by the separation net. The solid-liquid two-phase cooling medium is arranged in at least two layers in the direction away from the battery array, the phase change temperature of the layer adjacent to the heat source is lower than that of the layer far from the heat source, forming a gradient energy storage structure for step-by-step absorption of pulse heat. In operation, the phase change microcapsules absorb the pulse heat generated by the battery in latent heat to suppress temperature fluctuations; during charging, the cooling circulation unit forces cooling to restore the phase change material to a solid state. The present application combines gradient heat storage and pulse heat management, and is particularly suitable for the severe pulse working condition of the luggage towing vehicle.

Description

Technical Field

[0001] This invention relates to the field of vehicle thermal management technology, and more specifically, to a battery thermal management system and method for a baggage tractor. Background Technology

[0002] With the development of electrification and automation, electric baggage towing vehicles are being used more and more widely. These vehicles operate under typically harsh, pulsating conditions, such as frequent high-rate charging and discharging (e.g., acceleration / braking of the baggage towing vehicle), leading to intense battery heat generation and large temperature fluctuations, severely impacting battery cycle life and safety. Simultaneously, to ensure operational stability and safety, baggage towing vehicles usually have specific counterweight requirements to increase friction.

[0003] In the field of battery thermal management, existing technologies are mainly divided into air cooling and liquid cooling. Air cooling solutions have a simple structure, but their heat dissipation capacity is limited, making it difficult to cope with the instantaneous large heat under pulsed operating conditions, which can easily lead to battery overheating and performance degradation. Liquid cooling solutions (such as cold plate liquid cooling) have strong heat dissipation capacity, but their systems are complex, and the added cooling components (such as pumps, pipes, and cold plates) introduce additional points of failure. In addition, traditional active cooling systems have a response delay, and their temperature control effect is poor for rapidly changing pulsed heat loads.

[0004] Baggage trolleys typically operate intermittently, with separate departure and arrival processes. For small airports, the distance from the terminal to the furthest parking stand is generally between 0.5 and 1.5 kilometers. For medium-sized airports, the distance is generally between 1.5 and 3.5 kilometers. For large / hub airports, the distance varies greatly. To a distant parking stand within the same terminal: 2 to 4 kilometers; to a stand in a different terminal or satellite terminal: 3 to 7 kilometers or more; in extreme cases (such as Beijing Daxing, Shanghai Pudong, Charles de Gaulle Airport, etc.): the one-way distance from the central sorting area to the furthest parking stand may exceed 8-10 kilometers.

[0005] Defects and shortcomings of existing technology: 1. The heat dissipation capacity is mismatched with the pulse operating conditions: Disadvantages of air-cooled solutions: Their heat dissipation efficiency is directly related to airflow velocity and temperature difference, and they have inherent physical bottlenecks of "small heat capacity and low specific heat capacity". Faced with the heat generated instantly, the air-cooled system "cannot dissipate or retain" the heat, which can easily cause the local temperature of the battery to rise sharply, exceeding the optimal operating window (usually 25-40℃), accelerating battery aging, and even triggering the thermal runaway safety threshold.

[0006] Traditional liquid cooling solutions suffer from response delays: While liquid cooling systems theoretically have stronger heat dissipation capabilities than air cooling, their active circulation system (pumps, valves, long pipelines) suffers from thermal inertia and control delays. From the moment a sensor detects a temperature rise to the time the controller issues a command to increase the coolant flow rate and ultimately dissipate the heat, the entire process involves a lag of several seconds to tens of seconds. This system response speed cannot keep up with the heat generation rate, resulting in the battery temperature "peaks" not being effectively smoothed out, leading to prolonged periods of large temperature fluctuations and impacting battery lifespan.

[0007] 2. System Complexity: To meet the heat dissipation requirements of multiple heat sources such as the vehicle cabin, battery, motor, and electronic control system, the system is forced to be highly integrated. This leads to a surge in the number of components such as cooling circuits, pipes, joints, valves, pumps, and sensors. Every joint, every section of pipe, and every valve is a potential leak or failure point. In industrial vehicles like baggage tractors, which are constantly exposed to vibration, impact, and dust, the risk of component failure is significantly increased.

[0008] 3. High energy consumption and large temperature fluctuations: To cope with the most severe peak heat loads, the system is usually designed with a very high maximum cooling capacity. However, under most medium and low load conditions, the system still operates at high power or frequently starts and stops, resulting in significant energy waste and directly shortening the vehicle's driving range. Traditional threshold-based switching control or simple PID control struggles to accurately track rapidly changing heat generation rates. This leads to potentially excessive internal temperature differences (ΔT) within the battery pack, and the average temperature fluctuating significantly around the target value.

[0009] 4. Safety challenges: Baggage tractors have extremely high safety requirements, and the complex refrigeration system has potential risks of failure, which may lead to safety hazards. Summary of the Invention

[0010] The present invention aims to provide a battery thermal management system and method for baggage tractors, in order to solve the technical problems of existing battery thermal management systems, such as slow response, large temperature fluctuation, system complexity, and low energy efficiency under pulsed operating conditions.

[0011] To achieve the above objectives, the present invention provides the following technical solution: A battery thermal management system for a baggage towing vehicle, comprising: Battery pack housing, configured to accommodate a battery array; The battery array is housed within the battery pack casing. A liquid cooling medium is filled inside the battery pack housing to immerse the battery array. A solid-liquid two-phase cooling medium is filled inside the battery pack housing and separated from the liquid phase cooling medium by an isolation mesh. The solid-liquid two-phase cooling medium consists of an insulating liquid phase carrier and phase change material microcapsules dispersed in the liquid phase carrier. Furthermore, the solid-liquid two-phase cooling medium is arranged in at least two layers along the direction away from the battery array, including a nearby heat source layer and a distant heat source layer. The phase change temperature of the phase change material microcapsules in the nearby heat source layer is set to be lower than that of the phase change material microcapsules in the distant heat source layer, so as to form a gradient energy storage structure that absorbs pulse heat step by step. The cooling circulation unit, connected to the battery pack housing, is used to cool the solid-liquid two-phase cooling medium during the charging of the luggage tractor, so that the phase change material microcapsules can be restored from a liquid state to a solid state. The control system is connected to the cooling circulation unit and controls the start-up, shutdown, and power of the cooling circulation unit.

[0012] Furthermore, the liquid carrier is an electronic fluorinated liquid.

[0013] Furthermore, the phase change energy of the phase change material microcapsules is configured to be greater than the heat generated by the battery array during use. The phase change temperature of the phase change material microcapsules in the adjacent heat source layer is set in the range of 28-32℃, and the phase change temperature of the phase change material microcapsules in the distant heat source layer is set in the range of 33-40℃. The phase change temperature of each layer is within the optimal operating temperature range of the battery.

[0014] Furthermore, the system also includes a motor, which is placed in the liquid cooling medium to drive the liquid cooling medium to circulate.

[0015] Furthermore, the system also includes a temperature sensor, which is placed in the liquid cooling medium and connected to the control system.

[0016] Furthermore, the cooling circulation unit is a heat pump air conditioning system for the cabin, and is equipped with a four-way reversing valve and multiple solenoid valves.

[0017] Furthermore, when the cabin is in cooling mode during vehicle use, the four-way reversing valve and solenoid valve are configured to exhaust cabin heat to the outside of the vehicle; when the cabin is in heating mode during vehicle use, the four-way reversing valve and solenoid valve are configured to absorb heat from the solid-liquid two-phase cooling medium.

[0018] Furthermore, during vehicle charging, the four-way reversing valve and solenoid valve are configured to remove the heat stored in the solid-liquid two-phase cooling medium.

[0019] Furthermore, the cooling circulation unit is a refrigerant pump heat dissipation system.

[0020] The present invention also provides a battery thermal management method for a baggage towing vehicle, applied to any of the above-mentioned systems, comprising the following steps: During the operation of the baggage tractor, the heat generated by the battery array is absorbed by the phase change material microcapsules in the solid-liquid two-phase cooling medium through the latent heat of phase change, so as to suppress the battery temperature peak and fluctuation. During the charging process of the baggage tractor, the cooling circulation unit is activated to force cooling of the solid-liquid two-phase cooling medium, so that the phase change material microcapsules change from liquid to solid, thereby restoring their heat storage capacity.

[0021] The working principle and beneficial effects of this invention are as follows: 1. Superior Pulse Thermal Management Capabilities: Utilizing phase change material microcapsules within a solid-liquid two-phase cooling medium, the latent heat of phase change efficiently absorbs the instantaneous surges in heat generated by the battery under pulsed operating conditions, controlling battery temperature peaks and fluctuations within the optimal operating range and significantly extending battery life. The microcapsules have a large specific surface area, short heat transfer paths, and ample contact with the cooling medium, resulting in rapid heat exchange. The liquid-phase cooling medium acts as a heat-conducting bridge, ensuring rapid heat transfer to the solid-liquid two-phase cooling medium, while the isolation mesh design prevents the phase change material microcapsules from interfering with the circulation of the liquid-phase cooling medium.

[0022] 2. Synergistic Optimization of Counterweight and Thermal Management: The battery pack casing, liquid-phase coolant, and solid-liquid two-phase coolant themselves have a certain mass, which can supplement the counterweight requirements of the baggage towing vehicle. This transforms the weight burden of traditional thermal management into a functional counterweight advantage, replacing some dedicated counterweights, effectively saving steel consumption. It achieves efficient thermal management while meeting the overall vehicle counterweight requirements, realizing structural integration, weight reduction and efficiency improvement, and cost optimization.

[0023] 3. Intrinsic safety and high reliability: The electronic fluorinated liquid has insulating and non-flammable properties, completely eliminating the risk of battery short circuit fire. The system eliminates the complex capillary tubes, cold plates, joints, and long external loops of traditional liquid cooling systems, resulting in a simple system structure that significantly reduces potential leakage points and mechanical failure points, making the system extremely robust.

[0024] 4. High System Energy Efficiency: The cooling circulation unit (e.g., utilizing the cabin air conditioning) is designed to meet only the cabin heat load and average battery heat dissipation requirements. It eliminates the need for a high-power compressor to handle sudden, excessive heat loads from the battery, reducing initial system costs and operating energy consumption. The cooling circulation unit avoids frequent start-stop cycles to handle pulsed heat, resulting in smoother operation and a longer lifespan. When cabin heating is required, waste heat generated by the battery and motor can be absorbed from the solid-liquid two-phase cooling medium within the battery pack, achieving energy recovery and improving overall vehicle energy efficiency. In low-temperature environments, a refrigerant pump cooling system can replace compression refrigeration for further reducing energy consumption.

[0025] 5. Excellent all-weather adaptability and temperature uniformity: Immersion cooling ensures excellent temperature uniformity within the battery pack. The battery pack casing, a large amount of cooling medium, and phase change material microcapsules together form a huge "heat storage pool," which, combined with the external insulation layer, has a large heat capacity. When the vehicle is stationary in winter, this system can effectively utilize its stored waste heat to keep the battery warm, solving the problem of reduced range in winter. Attached Figure Description

[0026] Figure 1 This is a system schematic diagram of the present invention; Reference numerals: 1. Battery pack housing; 2. Battery array; 3. Liquid phase cooling medium; 4. Solid-liquid two-phase cooling medium; 41. Adjacent heat source layer; 42. Distant heat source layer; 5. Isolation mesh; 6. Cooling circulation unit; 7. Temperature sensor; 8. Motor. Detailed Implementation

[0027] The invention will be further described in detail below with reference to the specific embodiments and accompanying drawings. Except for the contents specifically mentioned below, the processes, conditions, and experimental methods for implementing the invention are all common knowledge and general knowledge in the art, and the invention does not have any particular limitations.

[0028] like Figure 1 As shown, this embodiment provides a battery thermal management system for a luggage towing vehicle, including a battery pack housing 1, a battery array 2, a liquid phase cooling medium 3, a solid-liquid two-phase cooling medium 4, an adjacent heat source layer 41, a distant heat source layer 42, an isolation net 5, a cooling circulation unit 6, a temperature sensor 7, a motor 8, and a control system.

[0029] The battery pack housing 1 is made of a metallic material (such as steel or aluminum alloy) and has sufficient mass and strength, with an internal cavity. The exterior of the battery pack housing 1 may be covered with an insulation layer to reduce heat loss.

[0030] The battery array 2 consists of multiple cells (square, cylindrical or pouch) connected in series and parallel and arranged in a housing cavity. Gaps are left between the cells to facilitate the flow of cooling medium and heat exchange.

[0031] Liquid cooling medium 3 is filled at the bottom of the battery pack housing 1 to immerse the lower part of the battery array 2, serving as the main heat conduction medium. Liquid cooling medium 3 is preferably an insulating electronic fluorinated liquid with good thermal conductivity and electrical insulation.

[0032] The motor 8 is installed in the liquid cooling medium 3 to drive the liquid cooling medium 3 to circulate in the tank, enhance the convective heat transfer efficiency between the coolant and the surface of the battery cell, and make the heat quickly carried away from the surface of the battery cell and evenly distributed throughout the coolant.

[0033] A solid-liquid two-phase cooling medium 4 is filled in the upper part of the battery pack housing 1 and separated from the liquid phase cooling medium 3 by an isolation mesh 5. The solid-liquid two-phase cooling medium 4 is arranged in at least two layers along the direction away from the battery array, including a nearby heat source layer 41 and a distant heat source layer 42. The phase change temperature of the phase change material microcapsules in the nearby heat source layer is set to be lower than that of the phase change material microcapsules in the distant heat source layer, so as to form a gradient energy storage structure that absorbs pulse heat step by step. The layers are still separated by an isolation mesh, but the isolation mesh is changed to a thermally enhanced type (such as a surface coated with graphene).

[0034] The solid-liquid two-phase cooling medium 4 consists of an insulating liquid carrier and phase change material microcapsules dispersed in the liquid carrier. The liquid carrier is preferably an electronic fluorinated liquid, and the phase change energy is configured to be greater than the heat generated by the battery array 2 and the motor 8 during use. The phase change temperature of the phase change material microcapsules in the adjacent heat source layer 41 is set in the range of 28-32℃, and the phase change temperature of the phase change material microcapsules in the distant heat source layer 42 is set in the range of 33-40℃. The phase change temperature of each layer is within the optimal operating temperature range of the battery.

[0035] The function of the isolation net 5 is to prevent the phase change material microcapsules from entering the liquid phase cooling medium 3, so as to avoid affecting the circulation flow, while allowing heat to be transferred through the liquid phase cooling medium 3 to the solid-liquid two-phase cooling medium 4.

[0036] The cooling circulation unit 6 is connected to the battery pack housing 1 and is used to force-cool the solid-liquid two-phase cooling medium 4 when the baggage tractor is charging.

[0037] In this embodiment, the cooling circulation unit 6 adopts the cabin's heat pump air conditioning system. Figure 1 The connection between the heat pump air conditioning system and the cabin has been omitted. It is equipped with a four-way reversing valve and multiple solenoid valves, which can switch between different working modes by switching the valve circuit.

[0038] Temperature sensor 7 is placed in the liquid cooling medium 3 to detect the temperature of the cooling medium in real time. The control system is connected to temperature sensor 7 and cooling circulation unit 6, and is used to automatically control or manually control the start / stop and power of cooling circulation unit 6 based on the detected temperature signal.

[0039] The system operation method in this embodiment is as follows: During the operation of the baggage tractor, the heat generated by the battery array 2 is first transferred to the liquid phase cooling medium 3, and the liquid phase cooling medium 3 transfers the heat to the solid-liquid two-phase cooling medium 4 through convection. The phase change material microcapsules in the solid-liquid two-phase cooling medium 4 absorb a large amount of latent heat through phase change (solid to liquid), thereby suppressing the peak and fluctuation of the battery temperature.

[0040] If the cabin requires heating during the operation of the baggage tractor, the four-way reversing valve and solenoid valve are configured to absorb heat from the solid-liquid two-phase cooling medium and supply heat to the cabin, thereby improving the energy efficiency ratio and energy utilization efficiency.

[0041] If the cabin requires cooling during the operation of the baggage tractor, the four-way reversing valve and solenoid valve are configured to exhaust cabin heat to the outside of the vehicle, just like a normal air conditioning system.

[0042] When the baggage tractor's battery is depleted and it needs to be recharged, the control system activates the cooling circulation unit 6 to force-cool the solid-liquid two-phase cooling medium 4 based on the signal detected by the temperature sensor 7. Alternatively, the control system can be manually activated to activate the cooling circulation unit 6 to cool the phase change material microcapsules from a liquid state back to a solid state, thereby restoring their heat storage capacity and preparing them for the next working cycle.

[0043] In another embodiment, an alternative design is used for the cooling cycle unit. When the ambient temperature is below a set threshold (e.g., 10°C), a refrigerant pump cooling system can be used instead of a compression refrigeration system as the cooling cycle unit 6. The refrigerant pump cooling system uses a refrigerant pump to drive the refrigerant circulation and dissipates heat to the environment through an outdoor heat exchanger. Compared to compression refrigeration, it consumes less power and is suitable for charging cooling scenarios in low-temperature environments. Other structures and operating methods are the same as in Embodiment 1.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0045] The working principle and beneficial effects of this invention are as follows: 1. Superior Pulse Thermal Management Capabilities: Utilizing phase change material microcapsules within a solid-liquid two-phase cooling medium, the latent heat of phase change efficiently absorbs the instantaneous surges in heat generated by the battery under pulsed operating conditions, controlling battery temperature peaks and fluctuations within the optimal operating range and significantly extending battery life. The microcapsules have a large specific surface area, short heat transfer paths, and ample contact with the cooling medium, resulting in rapid heat exchange. The liquid-phase cooling medium acts as a heat-conducting bridge, ensuring rapid heat transfer to the solid-liquid two-phase cooling medium, while the isolation mesh design prevents the phase change material microcapsules from interfering with the circulation of the liquid-phase cooling medium.

[0046] 2. Synergistic Optimization of Counterweight and Thermal Management: The battery pack casing, liquid-phase coolant, and solid-liquid two-phase coolant themselves have a certain mass, which can supplement the counterweight requirements of the baggage towing vehicle. This transforms the weight burden of traditional thermal management into a functional counterweight advantage, replacing some dedicated counterweights, effectively saving steel consumption. It achieves efficient thermal management while meeting the overall vehicle counterweight requirements, realizing structural integration, weight reduction and efficiency improvement, and cost optimization.

[0047] 3. Intrinsic safety and high reliability: The electronic fluorinated liquid has insulating and non-flammable properties, completely eliminating the risk of battery short circuit fire. The system eliminates the complex capillary tubes, cold plates, joints, and long external loops of traditional liquid cooling systems, resulting in a simple system structure that significantly reduces potential leakage points and mechanical failure points, making the system extremely robust.

[0048] 4. High System Energy Efficiency: The power design of the cooling circulation unit (such as utilizing the cabin air conditioning) only needs to meet the cabin heat load and the average heat dissipation requirements of the battery. There is no need to design a high-power compressor to cope with the instantaneous high heat load of the battery, reducing the initial system cost and operating energy consumption. The external cooling circulation unit does not need frequent start-stop to cope with pulsed heat, resulting in smoother operation and a longer lifespan. When the cabin needs heating, waste heat generated by the battery and motor can be absorbed from the solid-liquid two-phase cooling medium within the battery pack, achieving energy recovery and improving the overall vehicle energy utilization efficiency. In low-temperature environments, a refrigerant pump cooling system can be used instead of compression refrigeration for cooling, further reducing energy consumption.

[0049] 5. Excellent all-weather adaptability and temperature uniformity: Immersion cooling ensures excellent temperature uniformity within the battery pack. The battery pack casing, a large amount of cooling medium, and phase change material microcapsules together form a huge "heat storage pool," which, combined with the external insulation layer, has a large heat capacity. When the vehicle is stationary in winter, this system can effectively utilize its stored waste heat to keep the battery warm, solving the problem of reduced range in winter.

Claims

1. A battery thermal management system for a baggage tractor, characterized in that, include: Battery pack housing, configured to accommodate a battery array; A battery array is disposed within the battery pack housing; A liquid cooling medium is filled inside the battery pack housing to immerse the battery array; A solid-liquid two-phase cooling medium is filled inside the battery pack casing and separated from the liquid-phase cooling medium by an insulating mesh. The solid-liquid two-phase cooling medium consists of an insulating liquid carrier and phase change material microcapsules dispersed in the liquid carrier. Furthermore, the solid-liquid two-phase cooling medium is arranged in at least two layers along the direction away from the battery array, including a proximity heat source layer and a distance heat source layer. The phase change temperature of the phase change material microcapsules in the proximity heat source layer is set lower than that in the distance heat source layer to form a gradient energy storage structure that absorbs pulsed heat step by step. The phase change energy of the phase change material microcapsules is configured to be greater than the heat generated by the battery array during use. The phase change temperature of the phase change material microcapsules in the proximity heat source layer is set in the range of 28-32°C, and the phase change temperature of the phase change material microcapsules in the distance heat source layer is set in the range of 33-40°C. The phase change temperature of each layer is within the optimal operating temperature range of the battery. A temperature sensor is placed in a liquid cooling medium and connected to the control system. The cooling circulation unit is connected to the battery pack housing and cools the solid-liquid two-phase cooling medium when the luggage tractor is charging, so that the phase change material microcapsules are restored from a liquid state to a solid state; The control system is connected to the cooling circulation unit and controls the start-up, shutdown, and power of the cooling circulation unit.

2. The battery thermal management system for a baggage tractor according to claim 1, characterized in that, The liquid carrier is an electronic fluorinated liquid.

3. The battery thermal management system for a baggage tractor according to claim 1, characterized in that, It also includes a motor, which is disposed in the liquid cooling medium and drives the liquid cooling medium to circulate.

4. The battery thermal management system for a baggage tractor according to claim 1, characterized in that, The cooling circulation unit is a cabin heat pump air conditioning system, and is equipped with a four-way reversing valve and multiple solenoid valves.

5. The battery thermal management system for a baggage tractor according to claim 4, characterized in that, When the cabin is in cooling mode during vehicle use, the four-way reversing valve and solenoid valve are configured to exhaust cabin heat to the outside of the vehicle; when the cabin is in heating mode during vehicle use, the four-way reversing valve and solenoid valve are configured to absorb heat from the solid-liquid two-phase cooling medium.

6. The battery thermal management system for a baggage tractor according to claim 4, characterized in that, When the vehicle is charging, the four-way reversing valve and solenoid valve are configured to remove the heat stored in the solid-liquid two-phase cooling medium.

7. The battery thermal management system for a baggage tractor according to claim 1, characterized in that, The cooling circulation unit is a fluorine pump heat dissipation system.

8. A battery thermal management method for a baggage tractor, applied to the system described in any one of claims 1 to 7, characterized in that, Includes the following steps: During the operation of the baggage tractor, the heat generated by the battery array is absorbed by the phase change material microcapsules in the solid-liquid two-phase cooling medium through the latent heat of phase change, thus suppressing the battery temperature peak and fluctuation. During the charging process of the baggage tractor, the cooling circulation unit is activated to force cooling of the solid-liquid two-phase cooling medium, causing the phase change material microcapsules to change from liquid to solid and restore their heat storage capacity.

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