A pressure control method and working method for a negative pressure liquid cooling system

Abstract

This application relates to the field of lithium battery thermal management technology, and in particular to a pressure control method and operating method for a negative pressure liquid cooling system. The negative pressure liquid cooling system includes a differential pressure supply unit, a cooling unit, and a heat exchange unit. During system operation, it mainly includes two operating modes. In the first operating mode, a vacuum pump continuously evacuates air from the first liquid storage tank through a first evacuation valve to maintain a negative pressure state within the first liquid storage tank. Simultaneously, a small amount of air is continuously introduced into the first liquid storage tank through a first auxiliary air supply valve to maintain the low pressure value within the first liquid storage tank within a certain range. In the second operating mode, a vacuum pump continuously evacuates air from the second liquid storage tank through a second evacuation valve to maintain a negative pressure state within the second liquid storage tank. Simultaneously, a small amount of air is continuously introduced into the second liquid storage tank through a second auxiliary air supply valve to maintain the low pressure value within the second liquid storage tank within a certain range.

Description

Technical Field

[0001] This application relates to the field of lithium battery thermal management technology, and in particular to a pressure control method and operating method of a negative pressure liquid cooling system. Background Technology

[0002] Lithium-ion battery thermal management systems provide an effective thermally stable environment for lithium-ion batteries in pure electric vehicles. Compared to air-cooled systems, liquid cooling systems have higher heat dissipation efficiency and better heat dissipation effects, and are more widely used in lithium-ion battery thermal management.

[0003] Existing negative pressure liquid cooling systems for lithium battery thermal management include a first liquid storage tank, a second liquid storage tank, and a vacuum pump. The vacuum pump is connected to both the first and second liquid storage tanks. The vacuum pump maintains a negative pressure inside the first / second liquid storage tank, while keeping the inside of the second / first liquid storage tank at normal pressure. This pressure difference forces the coolant to flow through the pipes, thus cooling the lithium battery. However, maintaining this negative pressure requires more than just pumping air to keep the pressure stable, often resulting in excessively low pressure. This can cause the coolant to fall below its saturation pressure, leading to cavitation or boiling, which in turn affects heat dissipation and can damage the vacuum pump.

[0004] The existing technical solutions mentioned above have the following drawbacks: During the maintenance of the negative pressure state in the first liquid storage tank / second liquid storage tank, it is difficult to keep the pressure value stable by relying solely on air pumping. This often leads to the pressure value being too low, causing the coolant to fall below the saturation pressure and resulting in cavitation or boiling, which in turn affects the heat dissipation effect and damages the vacuum pump. Summary of the Invention

[0005] In order to maintain a stable pressure value during the negative pressure state and avoid excessively low pressure, this application provides a pressure control method and operating method for a negative pressure liquid cooling system.

[0006] The primary objective of this application is to provide a pressure control method for a negative pressure liquid cooling system, employing the following technical solution: A pressure control method for a negative pressure liquid cooling system, the negative pressure liquid cooling system comprising: The differential pressure supply unit includes a first liquid storage tank, a second liquid storage tank, a vacuum pump, a gas-liquid separator, and a first three-way valve. The inlet of the vacuum pump is connected to the first liquid storage tank via a first suction valve, and the inlet is connected to the second liquid storage tank via a second suction valve. The outlet is connected to the inlet of the gas-liquid separator. One port of the first three-way valve is connected to the gas outlet of the gas-liquid separator, another port is connected to the first liquid storage tank via a first main air supply valve and a first auxiliary air supply valve, another port is connected to the second liquid storage tank via a second main air supply valve and a second auxiliary air supply valve, and the last port is connected to the atmosphere. The cooling unit is connected to the differential pressure liquid supply unit; the cooling unit is also connected to the cold plate of the lithium battery used in conjunction with the negative pressure liquid cooling system, and is used to cool the lithium battery. The heat exchange unit is used for heat exchange with the coolant; Pressure control methods for negative pressure liquid cooling systems include: Open the first suction valve, the first auxiliary air supply valve, and the second main air supply valve, and close the second suction valve, the first main air supply valve, and the second auxiliary air supply valve; the coolant from the second storage tank flows through the cold plate of the lithium battery and then reaches the first storage tank; Open the second suction valve, the first main air supply valve, and the second auxiliary air supply valve, and close the first suction valve, the first auxiliary air supply valve, and the second main air supply valve. The coolant from the first storage tank flows through the cold plate of the lithium battery and then reaches the second storage tank.

[0007] By adopting the above technical solution, in the first operating mode, the vacuum pump continuously evacuates the first liquid storage tank through the first evacuation valve to maintain a negative pressure state inside the first liquid storage tank. Simultaneously, a small amount of air is continuously introduced into the first liquid storage tank through the first auxiliary air supply valve to appropriately compensate for the air pressure inside the first liquid storage tank, keeping the pressure value inside the first liquid storage tank as constant as possible. This avoids excessively low pressure inside the first liquid storage tank, thereby preventing cavitation or boiling, ensuring heat dissipation, and preventing damage to the vacuum pump. A large amount of air is introduced into the second liquid storage tank through the second main air supply valve, allowing the interior of the second liquid storage tank to quickly return to normal pressure. Utilizing the pressure difference, the coolant in the second liquid storage tank flows through the heat exchange unit and the cold plate of the lithium battery before reaching the first liquid storage tank. Because the pressure difference between the second and first liquid storage tanks can be kept constant, the coolant flow rate is more stable. In the second operating mode, the vacuum pump continuously evacuates the second liquid storage tank through the second evacuation valve to maintain a negative pressure state inside the second liquid storage tank. Simultaneously, a small amount of air is continuously introduced into the second reservoir through the second auxiliary air supply valve to appropriately compensate for the air pressure inside the second reservoir, keeping the pressure value inside the second reservoir as constant as possible. This prevents the pressure inside the second reservoir from becoming too low, thus avoiding cavitation or boiling, ensuring effective heat dissipation, and preventing damage to the vacuum pump. A large amount of air is introduced into the first reservoir through the first main air supply valve, quickly restoring the internal pressure of the first reservoir to normal. Utilizing the pressure difference, the coolant in the first reservoir flows through the heat exchange unit and the cold plate of the lithium battery before reaching the second reservoir. Because the pressure difference between the first and second reservoirs can be kept constant, the coolant flow rate is more stable. Overall, using pressure difference to drive the coolant flow eliminates the need for a water pump, reducing the number of components and lowering costs. The simplified system effectively reduces the failure rate and control difficulty. Moreover, the negative pressure delivery method significantly reduces the risk of coolant leakage.

[0008] This application further specifies that: the orifice diameter of the first auxiliary air supply valve is smaller than that of the first main air supply valve; and the orifice diameter of the second auxiliary air supply valve is smaller than that of the second main air supply valve.

[0009] This application further specifies that the differential pressure supply unit also includes: The first low liquid level sensor is installed on the first liquid storage tank and is used to detect the liquid level of the coolant in the first liquid storage tank; The first high liquid level sensor is installed on the first liquid storage tank and is used to detect the liquid level of the coolant in the first liquid storage tank; The second low liquid level sensor is installed on the second liquid storage tank and is used to detect the liquid level of the coolant in the second liquid storage tank. The second high liquid level sensor is installed on the second liquid storage tank and is used to detect the liquid level of the coolant in the second liquid storage tank; The first pressure sensor is installed on the first liquid storage tank and is used to detect the air pressure inside the first liquid storage tank; The second pressure sensor is installed on the second liquid storage tank and is used to detect the air pressure inside the second liquid storage tank.

[0010] By adopting the above technical solution, the liquid level detection signal serves as the trigger signal for switching between the first and second operating modes. When the coolant level in the first reservoir reaches the height of the first high-level sensor, the system switches from the first operating mode to the second operating mode. When the coolant level in the second reservoir reaches the height of the second high-level sensor, the system switches from the second operating mode back to the first operating mode. When the coolant level in either the first or second reservoir is lower than the height of the first or second low-level sensor, it indicates that the liquid level is too low and replenishment is required.

[0011] This application further specifies that the cooling unit includes: The liquid inlet manifold is connected to the cold plate of the lithium battery. The liquid outlet tube is connected to the cold plate of the lithium battery; The second three-way valve has one valve port connected to the first liquid storage tank, another valve port connected to the inlet main pipe through the first main pipe, and yet another valve port connected to the outlet main pipe through the second main pipe. The third three-way valve has one port connected to the second liquid storage tank, another port connected to the inlet main pipe via the third main pipe, and yet another port connected to the outlet main pipe via the fourth main pipe.

[0012] By adopting the above technical solution, in the first operating mode, the coolant from the second storage tank flows sequentially through the third three-way valve, the heat exchanger, and the inlet main pipe before flowing into the cold plate of the lithium battery, and then sequentially through the outlet main pipe and the second three-way valve before flowing into the first storage tank. In the second operating mode, the coolant from the first storage tank flows sequentially through the second three-way valve, the heat exchanger, and the inlet main pipe before flowing into the cold plate of the lithium battery, and then sequentially through the outlet main pipe and the third three-way valve before flowing into the first storage tank. The flow direction of the coolant can be controlled by the second and third three-way valves, eliminating the need for additional valves, thus simplifying the structure and reducing the failure rate.

[0013] This application further specifies that the cooling unit also includes: A flow sensor, installed on the inlet main pipe, is used to detect the flow rate inside the inlet main pipe; The first temperature sensor is installed on the inlet manifold and is used to detect the temperature of the coolant in the inlet manifold. The third pressure sensor is installed on the inlet main pipe and is used to detect the pressure inside the inlet main pipe; The second temperature sensor is installed on the outlet main pipe and is used to detect the temperature of the coolant in the outlet main pipe; The fourth pressure sensor is installed on the outlet main pipe and is used to detect the pressure inside the outlet main pipe; The first flow regulating valve is installed on the liquid outlet main pipe and is used to regulate the flow rate in the liquid outlet main pipe.

[0014] By adopting the above technical solution, when the second temperature sensor detects that the temperature of the coolant flowing out of the cold plate is higher than a preset value, the opening of the first flow regulating valve is reduced to decrease the coolant flow rate. When the second temperature sensor detects that the temperature of the coolant flowing out of the cold plate is lower than the preset value, the opening of the first flow regulating valve is increased to increase the coolant flow rate. Based on the operating conditions of the lithium battery, the flow resistance of the circulating return flow is changed by adjusting the opening of the first flow regulating valve. Combined with negative pressure regulation, this achieves precise control of the coolant flow rate and temperature, preventing the cold plate from becoming too cold or too hot, and improving energy efficiency.

[0015] This application further specifies that: the first air extraction valve, the second air extraction valve, the first main air supply valve, the first auxiliary air supply valve, the second main air supply valve, the second auxiliary air supply valve, the second three-way valve, and the third three-way valve are pneumatic valves; and the first flow regulating valve is an electric valve.

[0016] This application further specifies that the heat exchange unit includes: The heat exchanger has a heat exchange medium inlet, a heat exchange medium outlet, a coolant inlet, and a coolant outlet; the coolant inlet is connected to the first main pipe and the third main pipe respectively; the coolant outlet is connected to the inlet main pipe. The heat exchange medium inlet pipe is connected to the heat exchange medium inlet. The heat exchange medium outlet pipe is connected to the heat exchange medium outlet.

[0017] This application further specifies that the heat exchange unit also includes: The third temperature sensor is installed on the heat exchange medium inlet pipe and is used to detect the temperature of the heat exchange medium inside the heat exchange medium inlet pipe. The fifth pressure sensor is installed on the heat exchange medium inlet pipe and is used to detect the pressure inside the heat exchange medium inlet pipe; The fourth temperature sensor is installed on the heat exchange medium output pipe and is used to detect the temperature of the heat exchange medium inside the heat exchange medium output pipe. The sixth pressure sensor is installed on the heat exchange medium output pipe and is used to detect the pressure inside the heat exchange medium output pipe. The second flow regulating valve is installed on the heat exchange medium output pipe and is used to regulate the flow rate in the heat exchange medium output pipe.

[0018] By adopting the above technical solution, when the first temperature sensor detects that the temperature of the coolant about to flow into the cold plate is higher than a preset value, the opening of the second flow regulating valve increases to increase the flow rate of the heat exchange medium, thereby improving the heat exchange efficiency. When the first temperature sensor detects that the temperature of the coolant about to flow into the cold plate is lower than the preset value, the opening of the second flow regulating valve decreases to reduce the flow rate of the heat exchange medium, thereby reducing the heat exchange efficiency.

[0019] The second objective of this application is to provide a working method for a negative pressure liquid cooling system, employing the following technical solution: A method for operating a negative pressure liquid cooling system, including two operating modes; In the first operating mode, the vacuum pump continuously evacuates the first liquid storage tank through the first evacuation valve to maintain a negative pressure state inside the first liquid storage tank. At the same time, air is continuously supplied to the first liquid storage tank through the first auxiliary air supply valve to maintain the pressure value inside the first liquid storage tank within a preset range. Air is supplied to the second liquid storage tank through the second main air supply valve to restore the interior of the second liquid storage tank to a normal pressure state. Utilizing the pressure difference, the coolant from the second liquid storage tank flows sequentially through the third three-way valve, the heat exchanger, and the inlet main pipe before flowing into the cold plate of the lithium battery, and then sequentially through the outlet main pipe and the second three-way valve before flowing into the first liquid storage tank. In the second operating mode, the vacuum pump continuously evacuates the second liquid storage tank through the second evacuation valve to maintain a negative pressure state inside the second liquid storage tank. At the same time, air is continuously supplied to the second liquid storage tank through the second auxiliary air supply valve to maintain the pressure value inside the second liquid storage tank within a preset range. Air is supplied to the first liquid storage tank through the first main air supply valve to restore the interior of the first liquid storage tank to a normal pressure state. Utilizing the pressure difference, the coolant from the first liquid storage tank flows sequentially through the second three-way valve, the heat exchanger, and the inlet main pipe before flowing into the cold plate of the lithium battery, and then sequentially through the outlet main pipe and the third three-way valve before flowing back into the first liquid storage tank.

[0020] In summary, the beneficial technical effects of this application are as follows: 1. In the first operating mode, the vacuum pump continuously evacuates the first liquid storage tank through the first evacuation valve to maintain a negative pressure state inside the tank. Simultaneously, a small amount of air is continuously introduced into the first liquid storage tank through the first auxiliary air supply valve to appropriately compensate for the pressure inside the tank, keeping the pressure as constant as possible and preventing excessively low pressure, thus avoiding cavitation or boiling, ensuring effective heat dissipation, and preventing damage to the vacuum pump. A large amount of air is introduced into the second liquid storage tank through the second main air supply valve, quickly restoring the internal pressure to normal. Utilizing the pressure difference, the coolant in the second liquid storage tank flows through the heat exchange unit and the cold plate of the lithium battery before reaching the first liquid storage tank. Because the pressure difference between the second and first liquid storage tanks remains constant, the coolant flow rate is more stable. In the second operating mode, the vacuum pump continuously evacuates the second liquid storage tank through the second evacuation valve to maintain a negative pressure state inside the tank. Simultaneously, a small amount of air is continuously introduced into the second reservoir through the second auxiliary air supply valve to appropriately compensate for the air pressure inside the second reservoir, keeping the pressure value inside the second reservoir as constant as possible. This prevents the pressure inside the second reservoir from becoming too low, thus avoiding cavitation or boiling, ensuring effective heat dissipation, and preventing damage to the vacuum pump. A large amount of air is introduced into the first reservoir through the first main air supply valve, quickly restoring the internal pressure of the first reservoir to normal. Utilizing the pressure difference, the coolant in the first reservoir flows through the heat exchange unit and the cold plate of the lithium battery before reaching the second reservoir. Because the pressure difference between the first and second reservoirs can be kept constant, the coolant flow rate is more stable. Overall, using pressure difference to drive the coolant flow eliminates the need for a water pump, reducing the number of components and lowering costs. The simplified system effectively reduces the failure rate and control difficulty. Moreover, the negative pressure delivery method significantly reduces the risk of coolant leakage.

[0021] 2. The liquid level detection signal serves as the trigger signal for switching between the first and second operating modes. When the coolant level in the first reservoir reaches the height of the first high-level sensor, the system switches from the first operating mode to the second operating mode. When the coolant level in the second reservoir reaches the height of the second high-level sensor, the system switches from the second operating mode back to the first operating mode. When the coolant level in either the first or second reservoir is lower than the height of the first or second low-level sensor, it indicates that the liquid level is too low and replenishment is required.

[0022] 3. In the first operating mode, coolant from the second reservoir flows sequentially through the third three-way valve, heat exchanger, and inlet main before entering the cold plate of the lithium battery, and then flows sequentially through the outlet main and the second three-way valve before entering the first reservoir. In the second operating mode, coolant from the first reservoir flows sequentially through the second three-way valve, heat exchanger, and inlet main before entering the cold plate of the lithium battery, and then flows sequentially through the outlet main and the third three-way valve before entering the first reservoir. The flow direction of the coolant can be controlled by the second and third three-way valves, eliminating the need for additional valves, thus simplifying the structure and reducing the failure rate.

[0023] 4. When the second temperature sensor detects that the temperature of the coolant flowing out of the cold plate is higher than a preset value, the opening of the first flow regulating valve is reduced to decrease the coolant flow rate. When the second temperature sensor detects that the temperature of the coolant flowing out of the cold plate is lower than a preset value, the opening of the first flow regulating valve is increased to increase the coolant flow rate. Based on the operating conditions of the lithium battery, the flow resistance of the circulating return flow is changed by adjusting the opening of the first flow regulating valve. Combined with negative pressure regulation, this achieves precise control of the coolant flow rate and temperature, preventing the cold plate from becoming too cold or too hot, and improving energy efficiency.

[0024] 5. When the first temperature sensor detects that the temperature of the coolant about to flow into the cold plate is higher than a preset value, the opening of the second flow regulating valve increases to increase the flow rate of the heat exchange medium, thereby improving the heat exchange efficiency. When the first temperature sensor detects that the temperature of the coolant about to flow into the cold plate is lower than the preset value, the opening of the second flow regulating valve decreases to reduce the flow rate of the heat exchange medium, thereby reducing the heat exchange efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the working principle of an embodiment of a negative pressure liquid cooling system; Figure 2 yes Figure 1 The diagram shown is a schematic of the negative pressure liquid cooling system in its first operating mode. Figure 3 yes Figure 1 The diagram shown is a schematic of the negative pressure liquid cooling system in its second operating mode.

[0026] Reference numerals: 110, Differential pressure supply unit; 111, First storage tank; 112, Second storage tank; 113, Vacuum pump; 114, Gas-liquid separator; 1151, First suction valve; 1152, Second suction valve; 1153, First main air supply valve; 1154, First auxiliary air supply valve; 1155, Second main air supply valve; 1156, Second auxiliary air supply valve; 1161, First low level sensor; 1162, First high level sensor; 1163, Second low level sensor; 1164, Second high level sensor; 1165, First pressure sensor; 1166, Second pressure sensor; 120, Cooling unit; 121, Inlet... 122. Liquid outlet pipe; 123. Second three-way valve; 124. Third three-way valve; 1251. Flow sensor; 1252. First temperature sensor; 1253. Third pressure sensor; 1254. Second temperature sensor; 1255. Fourth pressure sensor; 126. First flow regulating valve; 130. Heat exchange unit; 131. Heat exchanger; 132. Heat exchange medium inlet pipe; 133. Heat exchange medium outlet pipe; 1341. Third temperature sensor; 1342. Fifth pressure sensor; 1343. Fourth temperature sensor; 1344. Sixth pressure sensor; 1345. Second flow regulating valve; 200. Cold plate. Detailed Implementation

[0027] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0028] Reference Figure 1 , Figure 2 and Figure 3This application discloses a pressure control method for a negative pressure liquid cooling system. The negative pressure liquid cooling system includes a differential pressure supply unit 110, a cooling unit 120, and a heat exchange unit 130. The differential pressure supply unit 110 is used to supply and recover coolant. The differential pressure supply unit 110 is equipped with a first liquid storage tank 111, a second liquid storage tank 112, a vacuum pump 113, a gas-liquid separator 114, and a first three-way valve. The inlet of the vacuum pump 113 is connected to the first liquid storage tank 111 through a first suction valve 1151, the inlet is connected to the second liquid storage tank 112 through a second suction valve 1152, and the outlet is connected to the inlet of the gas-liquid separator 114. One port of the first three-way valve is connected to the gas outlet of the gas-liquid separator 114, another port is connected to the first liquid storage tank 111 via the first main gas supply valve 1153 and the first auxiliary gas supply valve 1154, another port is connected to the second liquid storage tank 112 via the second main gas supply valve 1155 and the second auxiliary gas supply valve 1156, and the last port is connected to the atmosphere. The gas-liquid separator 114 is used to separate gas and liquid, so that the gas flowing to the first liquid storage tank 111 / second liquid storage tank 112 is no longer mixed with liquid. The cooling unit 120 is connected to the differential pressure supply unit 110. The cooling unit 120 is connected to the cold plate 200 of the lithium battery used in conjunction with the negative pressure liquid cooling system, and is used to cool the lithium battery. Before the coolant flows into the cold plate 200 of the lithium battery, the heat exchange unit 130 exchanges heat with the coolant to keep the temperature of the coolant below room temperature. The pressure control method of the negative pressure liquid cooling system includes: opening the first suction valve 1151, the first auxiliary air supply valve 1154, and the second main air supply valve 1155, and closing the second suction valve 1152, the first main air supply valve 1153, and the second auxiliary air supply valve 1156. Coolant from the second storage tank 112 flows through the cold plate 200 of the lithium battery and then reaches the first storage tank 111. Opening the second suction valve 1152, the first main air supply valve 1153, and the second auxiliary air supply valve 1156, and closing the first suction valve 1151, the first auxiliary air supply valve 1154, and the second main air supply valve 1155, coolant from the first storage tank 111 flows through the cold plate 200 of the lithium battery and then reaches the second storage tank 112. In the first operating mode, such as... Figure 2As shown, the first suction valve 1151, the first auxiliary air supply valve 1154, and the second main air supply valve 1155 are opened, while the second suction valve 1152, the first main air supply valve 1153, and the second auxiliary air supply valve 1156 are closed. The vacuum pump 113 continuously evacuates the first liquid storage tank 111 through the first suction valve 1151 to maintain a negative pressure state inside the first liquid storage tank 111. Simultaneously, a small amount of air is continuously introduced into the first liquid storage tank 111 through the first auxiliary air supply valve 1154 to appropriately compensate for the air pressure inside the first liquid storage tank 111, keeping the pressure value inside the first liquid storage tank 111 as constant as possible. This avoids excessively low pressure inside the first liquid storage tank 111, thereby preventing cavitation or boiling phenomena, ensuring effective heat dissipation, and preventing damage to the vacuum pump 113. A large amount of air is introduced into the second liquid storage tank 112 through the second main air supply valve 1155, causing the interior of the second liquid storage tank 112 to quickly return to normal pressure. Utilizing the pressure difference, the coolant in the second reservoir 112 flows through the heat exchange unit 130 and the cold plate 200 of the lithium battery before reaching the first reservoir 111. Because the pressure difference between the second reservoir 112 and the first reservoir 111 remains constant, the coolant flow rate is more stable. In the second operating mode, such as... Figure 3 As shown, the second suction valve 1152, the first main air supply valve 1153, and the second auxiliary air supply valve 1156 are opened, while the first suction valve 1151, the first auxiliary air supply valve 1154, and the second main air supply valve 1155 are closed. The vacuum pump 113 continuously evacuates the second liquid storage tank 112 through the second suction valve 1152 to maintain a negative pressure state inside the second liquid storage tank 112. Simultaneously, a small amount of air is continuously introduced into the second liquid storage tank 112 through the second auxiliary air supply valve 1156 to appropriately compensate for the air pressure inside the second liquid storage tank 112, keeping the pressure value inside the second liquid storage tank 112 as constant as possible. This avoids excessively low pressure inside the second liquid storage tank 112, thereby preventing cavitation or boiling phenomena, ensuring effective heat dissipation, and preventing damage to the vacuum pump 113. A large amount of air is introduced into the first liquid storage tank 111 through the first main air supply valve 1153, causing the interior of the first liquid storage tank 111 to quickly return to normal pressure. Utilizing the pressure difference, the coolant in the first reservoir 111 flows through the heat exchange unit 130 and the cold plate 200 of the lithium battery before reaching the second reservoir 112. Because the pressure difference between the first and second reservoirs 111 and 112 remains constant, the coolant flow rate is more stable. Overall, using pressure difference to drive the coolant flow eliminates the need for a water pump, reducing the number of components and lowering costs. The simplified system effectively reduces the failure rate and control complexity. Furthermore, the use of negative pressure delivery significantly reduces the risk of coolant leakage.

[0029] It should be noted that when the first liquid storage tank 111 / second liquid storage tank 112 is under negative pressure, the minimum negative pressure value is set according to the saturated vapor pressure of the coolant at the current temperature to prevent coolant evaporation.

[0030] In one embodiment, the orifice diameter of the first auxiliary air supply valve 1154 is smaller than that of the first main air supply valve 1153. The orifice diameter of the second auxiliary air supply valve 1156 is smaller than that of the second main air supply valve 1155. Thus, as needed, a large amount of air can be supplied to the first liquid storage tank 111 through the first main air supply valve 1153, a small amount of air can be supplied to the first liquid storage tank 111 through the first auxiliary air supply valve 1154, a large amount of air can be supplied to the second liquid storage tank 112 through the second main air supply valve 1155, and a small amount of air can be supplied to the second liquid storage tank 112 through the second auxiliary air supply valve 1156.

[0031] In one embodiment, reference is made to Figure 1 The differential pressure supply unit 110 further includes a first low level sensor 1161, a first high level sensor 1162, a second low level sensor 1163, a second high level sensor 1164, a first pressure sensor 1165, and a second pressure sensor 1166. The first low level sensor 1161 is installed on the first reservoir 111 and is used to detect the coolant level in the first reservoir 111. The first high level sensor 1162 is installed on the first reservoir 111 and is used to detect the coolant level in the first reservoir 111. The second low level sensor 1163 is installed on the second reservoir 112 and is used to detect the coolant level in the second reservoir 112. The second high level sensor 1164 is installed on the second reservoir 112 and is used to detect the coolant level in the second reservoir 112. The first pressure sensor 1165 is installed on the first reservoir 111 and is used to detect the air pressure inside the first reservoir 111. The second pressure sensor 1166 is installed on the second liquid reservoir 112 to detect the air pressure inside the second liquid reservoir 112. The liquid level detection signal serves as the trigger signal for switching between the first and second operating modes. When the coolant level in the first liquid reservoir 111 reaches the height of the first high liquid level sensor 1162, the system switches from the first operating mode to the second operating mode. When the coolant level in the second liquid reservoir 112 reaches the height of the second high liquid level sensor 1164, the system switches from the second operating mode to the first operating mode. When the coolant level in the first liquid reservoir 111 / second liquid reservoir 112 is lower than the height of the first low liquid level sensor 1161 / second low liquid level sensor 1163, it indicates that the liquid level is too low, triggering the alarm device and initiating liquid replenishment.

[0032] In one embodiment, the cooling unit 120 includes an inlet main pipe 121, an outlet main pipe 122, a second three-way valve 123, and a third three-way valve 124. The inlet main pipe 121 is connected to the cold plate 200 of the lithium battery. The outlet main pipe 122 is connected to the cold plate 200 of the lithium battery. One port of the second three-way valve 123 is connected to the first storage tank 111, another port is connected to the inlet main pipe 121 via the first main pipe, and yet another port is connected to the outlet main pipe 122 via the second main pipe. One port of the third three-way valve 124 is connected to the second storage tank 112, another port is connected to the inlet main pipe 121 via the third main pipe, and yet another port is connected to the outlet main pipe 122 via the fourth main pipe. In the first operating mode, as... Figure 2 As shown, the coolant from the second storage tank 112 flows sequentially through the third three-way valve 124, the heat exchanger 131, and the inlet main pipe 121 before flowing into the cold plate 200 of the lithium battery. It then flows sequentially through the outlet main pipe 122 and the second three-way valve 123 before flowing into the first storage tank 111. In the second operating mode, as... Figure 3 As shown, the coolant from the first reservoir 111 flows sequentially through the second three-way valve 123, the heat exchanger 131, and the inlet main pipe 121 before flowing into the cold plate 200 of the lithium battery. It then flows sequentially through the outlet main pipe 122 and the third three-way valve 124 before flowing back into the first reservoir 111. The flow direction of the coolant can be controlled by the second three-way valve 123 and the third three-way valve 124, eliminating the need for additional valves, thus simplifying the structure and reducing the failure rate.

[0033] Reference Figure 1In one embodiment, the cooling unit 120 further includes a flow sensor 1251, a first temperature sensor 1252, a third pressure sensor 1253, a second temperature sensor 1254, a fourth pressure sensor 1255, and a first flow regulating valve 126. The flow sensor 1251 is mounted on the inlet main pipe 121 and is used to detect the flow rate within the inlet main pipe 121. The first temperature sensor 1252 is mounted on the inlet main pipe 121 and is used to detect the temperature of the coolant within the inlet main pipe 121. The flow rate of the heat exchange medium is adjusted according to the temperature signal detected by the first temperature sensor 1252 to ensure that the coolant reaches the set temperature before flowing into the cold plate 200, which is beneficial to ensuring the cooling effect. The third pressure sensor 1253 is mounted on the inlet main pipe 121 and is used to detect the pressure within the inlet main pipe 121. The second temperature sensor 1254 is mounted on the outlet main pipe 122 and is used to detect the temperature of the coolant within the outlet main pipe 122. A fourth pressure sensor 1255 is installed on the outlet main pipe 122 to detect the pressure inside the outlet main pipe 122. A first flow regulating valve 126 is installed on the outlet main pipe 122 to regulate the flow rate inside the outlet main pipe 122. The opening of the first flow regulating valve 126 is controlled according to the temperature signal detected by the second temperature sensor 1254 or the flow signal detected by the flow sensor 1251. When the second temperature sensor 1254 detects that the temperature of the coolant flowing out of the cold plate 200 is higher than a preset value, the opening of the first flow regulating valve 126 is reduced to decrease the coolant flow rate. When the second temperature sensor 1254 detects that the temperature of the coolant flowing out of the cold plate 200 is lower than a preset value, the opening of the first flow regulating valve 126 is increased to increase the coolant flow rate. According to the working conditions of the lithium battery, the flow resistance of the circulating return is changed by adjusting the opening of the first flow regulating valve 126. In conjunction with the negative pressure regulation, precise control of the coolant flow rate and temperature is achieved, avoiding overcooling or overheating of the cold plate 200 and improving energy efficiency.

[0034] Preferably, the first suction valve 1151, the second suction valve 1152, the first main air supply valve 1153, the first auxiliary air supply valve 1154, the second main air supply valve 1155, the second auxiliary air supply valve 1156, the second three-way valve 123, the third three-way valve 124, the first air inlet valve 1181, and the second air inlet valve 1182 are pneumatic valves, which can respond quickly, improve pressure regulation speed, have high safety, and low manufacturing and maintenance costs. It should be noted that the corresponding valves can be controlled to operate via a pneumatic control cabinet. The first flow regulating valve 126 and the second flow regulating valve 1345 are electric valves, achieving precise flow regulation, with fast response speed, strong adaptability, and remote control capability.

[0035] It should be noted that the selection method for the first auxiliary air supply valve 1154 / second auxiliary air supply valve 1156 is as follows: First, use an electric regulating valve with the same inner diameter as the first suction valve 1151 / second suction valve 1152 to temporarily replace the first auxiliary air supply valve 1154 / second auxiliary air supply valve 1156 for calibration. With the first suction valve 1151 / second suction valve 1152 open, adjust the opening of the electric regulating valve and monitor the opening of the electric regulating valve when the pressure in the cavity stabilizes at the preset negative pressure value (such as -70kPa). Based on this opening characteristic, select the corresponding model of the first auxiliary air supply valve 1154 / second auxiliary air supply valve 1156.

[0036] Reference Figure 1 In one embodiment, the heat exchange unit 130 includes a heat exchanger 131, a heat exchange medium inlet pipe 132, a heat exchange medium outlet pipe 133, a third temperature sensor 1341, a fifth pressure sensor 1342, a fourth temperature sensor 1343, a sixth pressure sensor 1344, and a second flow regulating valve 1345. The heat exchanger 131 has a heat exchange medium inlet, a heat exchange medium outlet, a coolant inlet, and a coolant outlet. The coolant inlet is connected to a first main pipe and a third main pipe, respectively. The coolant outlet is connected to the inlet main pipe 121. The heat exchange medium inlet pipe 132 is connected to the heat exchange medium inlet. The heat exchange medium outlet pipe 133 is connected to the heat exchange medium outlet. The third temperature sensor 1341 is mounted on the heat exchange medium inlet pipe 132 and is used to detect the temperature of the heat exchange medium inside the heat exchange medium inlet pipe 132. The fifth pressure sensor 1342 is mounted on the heat exchange medium inlet pipe 132 and is used to detect the pressure inside the heat exchange medium inlet pipe 132. A fourth temperature sensor 1343 is installed on the heat exchange medium output pipe 133 to detect the temperature of the heat exchange medium inside the pipe. A sixth pressure sensor 1344 is installed on the heat exchange medium output pipe 133 to detect the pressure inside the pipe. A second flow regulating valve 1345 is installed on the heat exchange medium output pipe 133 to regulate the flow rate within the pipe. When the first temperature sensor 1252 detects that the temperature of the coolant about to flow into the cold plate 200 is higher than a preset value, the opening of the second flow regulating valve 1345 increases to increase the flow rate of the heat exchange medium, thereby improving the heat exchange efficiency. When the first temperature sensor 1252 detects that the temperature of the coolant about to flow into the cold plate 200 is lower than a preset value, the opening of the second flow regulating valve 1345 decreases to reduce the flow rate of the heat exchange medium, thereby reducing the heat exchange efficiency.

[0037] In one embodiment, the negative pressure liquid cooling system further includes a controller. The controller is electrically connected to the first low liquid level sensor 1161, the first high liquid level sensor 1162, the second low liquid level sensor 1163, the second high liquid level sensor 1164, the first pressure sensor 1165, the second pressure sensor 1166, the vacuum pump 113, the gas-liquid separator 114, the flow sensor 1251, the first temperature sensor 1252, the third pressure sensor 1253, the second temperature sensor 1254, the fourth pressure sensor 1255, the first flow regulating valve 126, the heat exchanger 131, the third temperature sensor 1341, the fifth pressure sensor 1342, the fourth temperature sensor 1343, the sixth pressure sensor 1344, the second flow regulating valve 1345, and the air compressor pump 117, respectively. The controller is capable of receiving detection signals and controlling the operation of each valve, the vacuum pump 113, the gas-liquid separator 114, the heat exchanger 131, and the air compressor pump 117 according to the detection signals.

[0038] This application also discloses a method for operating a negative pressure liquid cooling system, including two operating modes; In the first working mode, the vacuum pump 113 continuously pumps air from the first liquid storage tank 111 through the first air extraction valve 1151 to maintain a negative pressure state inside the first liquid storage tank 111. At the same time, air is continuously supplied to the first liquid storage tank 111 through the first auxiliary air supply valve 1154 to maintain the pressure value inside the first liquid storage tank 111 within a preset range. Air is supplied to the second liquid storage tank 112 through the second main air supply valve 1155 to restore the interior of the second liquid storage tank 112 to a normal pressure state. Utilizing the pressure difference, the coolant from the second liquid storage tank 112 flows sequentially through the third three-way valve 124, the heat exchanger 131, and the inlet main pipe 121 before flowing into the cold plate 200 of the lithium battery, and then sequentially through the outlet main pipe 122 and the second three-way valve 123 before flowing into the first liquid storage tank 111. In the second operating mode, the vacuum pump 113 continuously evacuates the second liquid storage tank 112 through the second evacuation valve 1152 to maintain a negative pressure state inside the second liquid storage tank 112. At the same time, air is continuously supplied to the second liquid storage tank 112 through the second auxiliary air supply valve 1156 to maintain the pressure value inside the second liquid storage tank 112 within a preset range. Air is supplied to the first liquid storage tank 111 through the first main air supply valve 1153 to restore the interior of the first liquid storage tank 111 to a normal pressure state. Utilizing the pressure difference, the coolant from the first liquid storage tank 111 flows sequentially through the second three-way valve 123, the heat exchanger 131, and the inlet main pipe 121 before flowing into the cold plate 200 of the lithium battery, and then sequentially through the outlet main pipe 122 and the third three-way valve 124 before flowing into the first liquid storage tank 111.

[0039] The implementation principle of this embodiment is as follows: In the first working mode, the first suction valve 1151, the first auxiliary air supply valve 1154, and the second main air supply valve 1155 are opened, while the second suction valve 1152, the first main air supply valve 1153, and the second auxiliary air supply valve 1156 are closed. The vacuum pump 113 continuously evacuates the first liquid storage tank 111 through the first suction valve 1151 to maintain a negative pressure state inside the first liquid storage tank 111. At the same time, a small amount of air is continuously supplied to the first liquid storage tank 111 through the first auxiliary air supply valve 1154 to appropriately compensate for the air pressure inside the first liquid storage tank 111, so that the pressure value inside the first liquid storage tank 111 is kept as constant as possible, avoiding the pressure value inside the first liquid storage tank 111 from being too low, thereby avoiding cavitation or boiling phenomena, thus ensuring the heat dissipation effect and preventing damage to the vacuum pump 113. A large amount of air is injected into the second liquid storage tank 112 through the second main air supply valve 1155, allowing the interior of the second liquid storage tank 112 to quickly return to normal pressure. Utilizing the pressure difference, the coolant in the second liquid storage tank 112 flows through the heat exchange unit 130 and the cold plate 200 of the lithium battery before reaching the first liquid storage tank 111. Because the pressure difference between the second liquid storage tank 112 and the first liquid storage tank 111 can remain constant, the coolant flow rate is more stable. In the second operating mode, such as... Figure 3 As shown, the second suction valve 1152, the first main air supply valve 1153, and the second auxiliary air supply valve 1156 are opened, while the first suction valve 1151, the first auxiliary air supply valve 1154, and the second main air supply valve 1155 are closed. The vacuum pump 113 continuously evacuates the second liquid storage tank 112 through the second suction valve 1152 to maintain a negative pressure state inside the second liquid storage tank 112. Simultaneously, a small amount of air is continuously introduced into the second liquid storage tank 112 through the second auxiliary air supply valve 1156 to appropriately compensate for the air pressure inside the second liquid storage tank 112, keeping the pressure value inside the second liquid storage tank 112 as constant as possible. This avoids excessively low pressure inside the second liquid storage tank 112, thereby preventing cavitation or boiling phenomena, ensuring effective heat dissipation, and preventing damage to the vacuum pump 113. A large amount of air is introduced into the first liquid storage tank 111 through the first main air supply valve 1153, causing the interior of the first liquid storage tank 111 to quickly return to normal pressure. Utilizing the pressure difference, the coolant in the first reservoir 111 flows through the heat exchange unit 130 and the cold plate 200 of the lithium battery before reaching the second reservoir 112. Because the pressure difference between the first and second reservoirs 111 and 112 remains constant, the coolant flow rate is more stable. Overall, using pressure difference to drive the coolant flow eliminates the need for a water pump, reducing the number of components and lowering costs. The simplified system effectively reduces the failure rate and control complexity. Furthermore, the use of negative pressure delivery significantly reduces the risk of coolant leakage.

[0040] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A pressure control method for a negative pressure liquid cooling system, characterized in that, The negative pressure liquid cooling system includes: The differential pressure supply unit (110) is equipped with a first liquid storage tank (111), a second liquid storage tank (112), a vacuum pump (113), a gas-liquid separator (114), and a first three-way valve. The inlet of the vacuum pump (113) is connected to the first liquid storage tank (111) through a first suction valve (1151), the inlet is connected to the second liquid storage tank (112) through a second suction valve (1152), and the outlet is connected to the inlet of the gas-liquid separator (114). One valve port of the first three-way valve is connected to the gas outlet of the gas-liquid separator (114), the other valve port is connected to the first liquid storage tank (111) through a first main gas supply valve (1153) and a first auxiliary gas supply valve (1154), the other valve port is connected to the second liquid storage tank (112) through a second main gas supply valve (1155) and a second auxiliary gas supply valve (1156), and the other valve port is connected to the atmosphere. A cooling unit (120) is connected to the differential pressure liquid supply unit (110); the cooling unit (120) is connected to the cold plate (200) of the lithium battery used in conjunction with the negative pressure liquid cooling system, and is used to cool the lithium battery; A heat exchange unit (130) is used for heat exchange with the coolant; The pressure control method of the negative pressure liquid cooling system includes: Open the first suction valve (1151), the first auxiliary air supply valve (1154), and the second main air supply valve (1155), and close the second suction valve (1152), the first main air supply valve (1153), and the second auxiliary air supply valve (1156); the coolant from the second liquid storage tank (112) flows through the cold plate (200) of the lithium battery and then reaches the first liquid storage tank (111); The second suction valve (1152), the first main air supply valve (1153), and the second auxiliary air supply valve (1156) are opened, and the first suction valve (1151), the first auxiliary air supply valve (1154), and the second main air supply valve (1155) are closed. The coolant from the first liquid storage tank (111) flows through the cold plate (200) of the lithium battery and then reaches the second liquid storage tank (112).

2. The pressure control method for the negative pressure liquid cooling system according to claim 1, characterized in that, The orifice diameter of the first auxiliary air supply valve (1154) is smaller than that of the first main air supply valve (1153); the orifice diameter of the second auxiliary air supply valve (1156) is smaller than that of the second main air supply valve (1155).

3. The pressure control method for the negative pressure liquid cooling system according to claim 1, characterized in that, The differential pressure supply unit (110) further includes: The first low liquid level sensor (1161) is installed on the first liquid storage tank (111) and is used to detect the liquid level of the coolant in the first liquid storage tank (111); The first high liquid level sensor (1162) is installed on the first liquid storage tank (111) and is used to detect the liquid level of the coolant in the first liquid storage tank (111); The second low liquid level sensor (1163) is installed on the second liquid storage tank (112) and is used to detect the liquid level of the coolant in the second liquid storage tank (112); The second high liquid level sensor (1164) is installed on the second liquid storage tank (112) and is used to detect the liquid level of the coolant in the second liquid storage tank (112); The first pressure sensor (1165) is installed on the first liquid storage tank (111) and is used to detect the air pressure inside the first liquid storage tank (111); The second pressure sensor (1166) is installed on the second liquid storage tank (112) and is used to detect the air pressure inside the second liquid storage tank (112).

4. The pressure control method for the negative pressure liquid cooling system according to claim 1, characterized in that, The cooling unit (120) includes: The liquid inlet pipe (121) is connected to the cold plate (200) of the lithium battery; The liquid outlet tube (122) is connected to the cold plate (200) of the lithium battery; The second three-way valve (123) has one valve port connected to the first liquid storage tank (111), another valve port connected to the inlet main pipe (121) through the first main pipe, and yet another valve port connected to the outlet main pipe (122) through the second main pipe. The third three-way valve (124) has one valve port connected to the second liquid storage tank (112), another valve port connected to the inlet main pipe (121) through the third main pipe, and yet another valve port connected to the outlet main pipe (122) through the fourth main pipe.

5. The pressure control method for the negative pressure liquid cooling system according to claim 4, characterized in that, The cooling unit (120) also includes: A flow sensor (1251) is installed on the inlet main pipe (121) and is used to detect the flow rate in the inlet main pipe (121); A first temperature sensor (1252) is installed on the inlet manifold (121) and is used to detect the temperature of the coolant in the inlet manifold (121); The third pressure sensor (1253) is installed on the inlet main pipe (121) and is used to detect the pressure inside the inlet main pipe (121); The second temperature sensor (1254) is installed on the outlet pipe (122) and is used to detect the temperature of the coolant in the outlet pipe (122); A fourth pressure sensor (1255) is installed on the liquid outlet tube (122) and is used to detect the pressure inside the liquid outlet tube (122); A first flow regulating valve (126) is installed on the liquid outlet main pipe (122) and is used to regulate the flow rate in the liquid outlet main pipe (122).

6. The pressure control method for the negative pressure liquid cooling system according to claim 5, characterized in that, The first suction valve (1151), the second suction valve (1152), the first main air supply valve (1153), the first auxiliary air supply valve (1154), the second main air supply valve (1155), the second auxiliary air supply valve (1156), the second three-way valve (123), and the third three-way valve (124) are pneumatic valves; the first flow regulating valve (126) is an electric valve.

7. The pressure control method for the negative pressure liquid cooling system according to claim 4, characterized in that, The heat exchange unit (130) includes: The heat exchanger (131) has a heat exchange medium inlet, a heat exchange medium outlet, a coolant inlet, and a coolant outlet; the coolant inlet is connected to the first main pipe and the third main pipe respectively; the coolant outlet is connected to the inlet main pipe (121); The heat exchange medium inlet pipe (132) is connected to the heat exchange medium inlet; The heat exchange medium outlet pipe (133) is connected to the heat exchange medium outlet.

8. The pressure control method for the negative pressure liquid cooling system according to claim 7, characterized in that, The heat exchange unit (130) also includes: The third temperature sensor (1341) is installed on the heat exchange medium input pipe (132) and is used to detect the temperature of the heat exchange medium in the heat exchange medium input pipe (132); The fifth pressure sensor (1342) is installed on the heat exchange medium input pipe (132) and is used to detect the pressure inside the heat exchange medium input pipe (132); A fourth temperature sensor (1343) is installed on the heat exchange medium output pipe (133) and is used to detect the temperature of the heat exchange medium in the heat exchange medium output pipe (133); The sixth pressure sensor (1344) is installed on the heat exchange medium output pipe (133) and is used to detect the pressure inside the heat exchange medium output pipe (133); The second flow regulating valve (1345) is installed on the heat exchange medium output pipe (133) and is used to regulate the flow rate in the heat exchange medium output pipe (133).

9. A method for operating a negative pressure liquid cooling system, characterized in that, Includes two working modes; In the first working mode, the vacuum pump (113) continuously pumps air from the first liquid storage tank (111) through the first air extraction valve (1151) to maintain a negative pressure state inside the first liquid storage tank (111); at the same time, air is continuously supplied into the first liquid storage tank (111) through the first auxiliary air supply valve (1154) to maintain the pressure value inside the first liquid storage tank (111) within a preset range; air is supplied into the second liquid storage tank (112) through the second main air supply valve (1155) to restore the interior of the second liquid storage tank (112) to a normal pressure state; using the pressure difference, the coolant from the second liquid storage tank (112) flows sequentially through the third three-way valve (124), the heat exchanger (131) and the liquid inlet pipe (121) into the cold plate (200) of the lithium battery, and then flows sequentially through the liquid outlet pipe (122) and the second three-way valve (123) into the first liquid storage tank (111); In the second operating mode, the vacuum pump (113) continuously evacuates the second liquid storage tank (112) through the second evacuation valve (1152) to maintain a negative pressure state inside the second liquid storage tank (112); at the same time, air is continuously supplied to the second liquid storage tank (112) through the second auxiliary air supply valve (1156) to maintain the pressure value inside the second liquid storage tank (112) within a preset range; air is supplied to the first liquid storage tank through the first main air supply valve (1153). Air is introduced into the tank (111) to restore the interior of the first liquid storage tank (111) to normal pressure. Using the pressure difference, the coolant from the first liquid storage tank (111) flows sequentially through the second three-way valve (123), the heat exchanger (131) and the liquid inlet pipe (121) into the cold plate (200) of the lithium battery, and then flows sequentially through the liquid outlet pipe (122) and the third three-way valve (124) into the first liquid storage tank (111).

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