JP2024048081A - Cooling System - Google Patents

Abstract

[Problem] To provide a cooling system capable of finely adjusting the level of a coolant. [Solution] A cooling system 1 includes a battery case 10 that houses a plurality of battery cells 11 and is supplied with coolant to immerse the battery cells 11, a heat exchanger 15 that exchanges heat with the coolant, a first communication passage 20 that allows the coolant to flow from the battery case 10 to the heat exchanger 15, a second communication passage 25 that allows the coolant to flow from the heat exchanger 15 to the battery case 10, a tank 30 that can store the coolant, and a first valve device 40 that is provided in the first communication passage 20 and is switchable between a first communication state that brings the battery case 10 and the heat exchanger 15 into communication with each other and a second communication state that brings the battery case 10 and the tank 30 into communication with each other. [Selected Figure] Figure 1

Description

The present invention relates to a cooling system that circulates a coolant between a battery case and a heat exchanger.

Electric vehicles that run on electricity output from a battery have become widespread. One example of technology related to such batteries is described in Patent Document 1, the source of which is shown below.

Patent Document 1 describes a battery pack. This battery pack contains multiple battery cells in a housing, and is provided with a first on-off valve, a second on-off valve, and a third on-off valve that adjust the level of cooling water in the housing. The first on-off valve, the second on-off valve, and the third on-off valve are controlled to open and close according to the temperature of the battery cells, and the higher the temperature of the battery cells, the greater the amount of the battery cells immersed in the cooling water.

JP 2021-89811 A

In the battery pack described in Patent Document 1, the opening and closing states of the first opening and closing valve, the second opening and closing valve, and the third opening and closing valve are controlled to adjust the level of the cooling water in the housing as described above. However, in this battery pack, the level of the cooling water can only be adjusted in three stages, and the level of the cooling water cannot be finely adjusted. As a result, the temperature of the battery pack cannot be appropriately adjusted.

Therefore, there is a need for a cooling system that can finely adjust the coolant level.

The cooling system according to the present invention is characterized in that it includes a battery case that houses multiple battery cells and is supplied with a cooling liquid to immerse the battery cells, a heat exchanger that exchanges heat with the cooling liquid, a first communication passage that allows the cooling liquid to flow from the battery case to the heat exchanger, a second communication passage that allows the cooling liquid to flow from the heat exchanger to the battery case, a tank that can store the cooling liquid, and a first valve device that is provided in the first communication passage and can be switched between a first communication state that brings the battery case and the heat exchanger into communication with each other and a second communication state that brings the battery case and the tank into communication with each other.

With this characteristic configuration, it is possible to store the coolant in the tank or to drain the coolant stored in the tank by switching the first valve device between the first and second communication states. This makes it possible to fine-tune the level of the coolant when immersing the battery cells housed in the battery case.

It is also preferable that the tank is arranged in parallel with the heat exchanger, and further includes a second valve device that is provided in the second communication passage and can be switched between a third communication state that brings the battery case and the heat exchanger into communication with each other, and a fourth communication state that brings the battery case and the tank into communication with each other.

With this configuration, the coolant can be easily stored in the tank and discharged from the tank depending on the respective states of the first valve device and the second valve device. This makes it possible to appropriately adjust the water level of the coolant in the battery case.

It is also preferable that the tank is capable of communicating with the battery case only through the first valve device, and that the coolant can be supplied and discharged in the second communication state.

With this configuration, the cooling system can be made smaller because only the first valve device is required.

It is also preferable to further include a first pump that circulates the cooling liquid between the battery case and the heat exchanger, and a second pump that supplies the cooling liquid stored in the tank to the battery case.

With this configuration, the first and second pumps can easily control the supply and discharge of coolant in the battery case, and the storage and discharge of coolant in the tank.

It is also preferable to further include a control unit that can switch between a first state in which the cooling liquid is circulated through a circulation path that includes the battery case, the heat exchanger, the first communication path, and the second communication path, a second state in which the cooling liquid is stored in the tank to reduce the amount of the cooling liquid in the circulation path, and a third state in which the cooling liquid is discharged from the tank to increase the amount of the cooling liquid in the circulation path.

With this configuration, for example, the control unit can automatically cool the battery cells according to the temperature of the coolant or the temperature of the battery (battery pack). This prevents deterioration of the power generation efficiency and charging efficiency of the battery (battery pack).

1 is a diagram showing a configuration of a cooling system according to a first embodiment. FIG. 2 is a diagram showing a first state according to the first embodiment; FIG. 4 is a diagram showing a second state according to the first embodiment; FIG. 11 is a diagram illustrating a third state according to the first embodiment. FIG. 11 is a diagram showing a configuration of a cooling system according to a second embodiment. FIG. 11 is a diagram illustrating a first state according to a second embodiment. FIG. 11 is a diagram showing a second state according to the second embodiment. FIG. 13 is a diagram illustrating a third state according to the second embodiment.

1. First embodiment A cooling system according to the present invention is configured to be capable of adjusting the water level when battery cells housed in a battery case are immersed in a cooling liquid. Hereinafter, a cooling system 1 of the present embodiment will be described.

Figure 1 is a block diagram showing the configuration of the cooling system 1 of this embodiment. As shown in Figure 1, the cooling system 1 is configured with a battery case 10, a heat exchanger 15, a first communication passage 20, a second communication passage 25, a tank 30, a first valve device 40, a second valve device 45, a first pump 50, a second pump 55, and a control unit 60. Each functional unit of the control unit 60 is constructed with hardware or software or both, with a CPU as the core component, in order to perform processing related to adjusting the water level when immersing the battery cells 11 housed in the battery case 10.

The battery case 10 contains multiple battery cells 11. The battery cells 11 form a battery (battery pack) 13. For example, multiple battery cells 11 are connected in parallel or series to form one battery 13.

The battery case 10 has a storage section 10A. The storage section 10A stores multiple battery cells 11.

The battery case 10 is configured so that the battery cells 11 can be immersed in a cooling liquid supplied thereto. The cooling liquid can be, for example, a liquid with high electrical insulation properties, such as a fluorine-based inert liquid or insulating oil.

The heat exchanger 15 exchanges heat with the coolant. As described below, the coolant discharged from the battery case 10 flows into the heat exchanger 15, and the heat exchanger 15 absorbs heat from the coolant to cool it. The coolant from which the heat has been absorbed is discharged from the heat exchanger 15 and supplied to the battery case 10.

The first communication passage 20 is provided between the exhaust port 10E of the battery case 10 and the inlet port 15I of the heat exchanger 15. This allows the first communication passage 20 to flow the coolant from the battery case 10 to the heat exchanger 15.

The second communication passage 25 is provided between the exhaust port 15E of the heat exchanger 15 and the inlet port 10I of the battery case 10. This allows the second communication passage 25 to flow the coolant from the heat exchanger 15 to the battery case 10.

The tank 30 is configured to be capable of storing cooling liquid. As described below, the tank 30 stores cooling liquid when the water level in which the battery cells 11 are immersed in the battery case 10 is lowered. This reduces the amount of cooling liquid flowing through the circulation path 2, which includes the battery case 10, the heat exchanger 15, the first communication path 20, and the second communication path 25. On the other hand, when the water level in which the battery cells 11 are immersed in the battery case 10 is raised, the cooling liquid is discharged from the tank 30. This increases the amount of cooling liquid flowing through the circulation path 2, which includes the battery case 10, the heat exchanger 15, the first communication path 20, and the second communication path 25.

The first valve device 40 is provided in the first communication passage 20. In this embodiment, the first valve device 40 is a three-way valve having three communication holes. Two of the three communication holes are provided to communicate with the first communication passage 20, and the remaining one communication hole is connected to the tank 30 via the third communication passage 31. The first valve device 40 is configured to be switchable between a first communication state and a second communication state. In the first communication state, the battery case 10 and the heat exchanger 15 are in a communication state, and in the second communication state, the battery case 10 and the tank 30 are in a communication state. In this embodiment, for ease of understanding, the part of the first communication passage 20 between the battery case 10 and the first valve device 40 is described as the first flow path 21, and the part of the first communication passage 20 between the first valve device 40 and the heat exchanger 15 is described as the second flow path 22.

The second valve device 45 is provided in the second communication passage 25. In this embodiment, the second valve device 45 is a three-way valve having three communication holes. Of the three communication holes, two are provided to communicate with the second communication passage 25, and the remaining one is connected to the tank 30 via the fourth communication passage 32. The second valve device 45 is configured to be switchable between a third communication state and a fourth communication state. In the third communication state, the battery case 10 and the heat exchanger 15 are in a communication state, and in the fourth communication state, the battery case 10 and the tank 30 are in a communication state. In this embodiment, for ease of understanding, the part of the second communication passage 25 between the heat exchanger 15 and the second valve device 45 is described as the third flow path 26, and the part of the second communication passage 25 between the second valve device 45 and the battery case 10 is described as the fourth flow path 27.

In this embodiment, the tank 30 is arranged in parallel with the heat exchanger 15 in the circulation path 2 via the first valve device 40 and the third communication passage 31, and the second valve device 45 and the fourth communication passage 32.

The first pump 50 is provided in the first flow path 21 between the battery case 10 and the first valve device 40 in the first communication passage 20, and circulates the coolant between the battery case 10 and the heat exchanger 15. The first pump 50 is also used to store the coolant in the tank 30.

The second pump 55 is provided in the fourth flow path 27 between the battery case 10 and the second valve device 45 in the second communication passage 25, and supplies the cooling liquid stored in the tank 30 to the battery case 10.

The control unit 60 controls the operation of the first valve device 40, the second valve device 45, the first pump 50, and the second pump 55 described above to switch the state of the cooling system 1 between the first state, the second state, and the third state.

2 shows an example in which the cooling system 1 is in the first state. In the first state, the control unit 60 circulates the coolant through the circulation path 2. As described above, the circulation path 2 is a flow path through which the coolant circulates, and is configured to include the battery case 10, the heat exchanger 15, the first communication path 20, and the second communication path 25. When the first state is to be set, the control unit 60 transmits a first instruction to the first valve device 40 to set the first valve device 40 to the first communication state (#111). As a result, the first flow path 21 and the second flow path 22 connected to the communication hole of the first valve device 40 are communicated with each other, and the valve body 40A of the first valve device 40 rotates so that the first flow path 21 and the second flow path 22 are not communicated with each other and the third communication path 31.

The control unit 60 also transmits a third instruction to the second valve device 45 to put the second valve device 45 into a third communication state (#112). As a result, the third flow path 26 and the fourth flow path 27 connected to the communication hole of the second valve device 45 are communicated with each other, and the valve body 45A of the second valve device 45 rotates so that the fourth communication path 32 is not communicated with the third flow path 26 and the fourth flow path 27.

The control unit 60 further transmits an operation command to the first pump 50 to operate the first pump 50 (#113). The control unit 60 also transmits a stop command to the second pump 55 to stop the second pump 55 (#114). At this time, the intake port and discharge port of the second pump 55 are in communication even when the second pump 55 is stopped. As a result, the coolant flows from the battery case 10 to the heat exchanger 15 via the first communication passage 20, and the coolant flows from the heat exchanger 15 to the battery case 10 via the second communication passage 25, and the coolant circulates through the circulation path 2.

Figure 3 shows an example of the cooling system 1 in the second state. In the second state, the control unit 60 stores the coolant in the tank 30. When the control unit 60 is to be in the second state, the control unit 60 transmits a second instruction to the first valve device 40 to put the first valve device 40 in the second communication state (#121). As a result, the valve body 40A of the first valve device 40 rotates so that the first flow path 21 and the third communication path 31 connected to the communication hole of the first valve device 40 are communicated with each other, and the first flow path 21 and the third communication path 31 are not communicated with each other.

The control unit 60 also transmits a third instruction to the second valve device 45 to put the second valve device 45 into a third communication state (#122). As a result, the third flow path 26 and the fourth flow path 27 connected to the communication hole of the second valve device 45 are communicated with each other, and the valve body 45A of the second valve device 45 rotates so that the fourth communication path 32 is not communicated with the third flow path 26 and the fourth flow path 27.

The control unit 60 further transmits an operation command to the first pump 50 to operate the first pump 50 (#123). The control unit 60 also transmits a stop command to the second pump 55 to stop the second pump 55 (#124). This causes the coolant to flow from the battery case 10 to the tank 30 via the first flow path 21 and the third communication path 31, where it is stored, and lowers the level of the coolant in the battery case 10. The control unit 60 may terminate the second state based on, for example, a water level sensor that detects the water level of the coolant in the battery case 10 or a water level sensor that detects the water level of the coolant in the tank 30.

Figure 4 shows an example of the cooling system 1 in the third state. In the third state, the control unit 60 discharges the coolant from the tank 30, raising the water level of the coolant in the battery case 10 and increasing the amount of coolant in the circulation path 2. When the control unit 60 is in the third state, it transmits a first instruction to the first valve device 40 to put the first valve device 40 in the first communication state (#131). As a result, the first flow path 21 and the second flow path 22 connected to the communication hole of the first valve device 40 are communicated with each other, and the valve body 40A of the first valve device 40 rotates so that the first flow path 21 and the second flow path 22 are not communicated with each other and the third communication path 31.

The control unit 60 also transmits a fourth instruction to the second valve device 45 to put the second valve device 45 into the fourth communication state (#132). As a result, the valve body 45A of the second valve device 45 rotates so that the fourth communication passage 32 connected to the communication hole of the second valve device 45 and the fourth flow path 27 are in communication with each other, and the fourth communication passage 32 and the fourth flow path 27 are not in communication with the third flow path 26.

The control unit 60 further transmits a stop command to the first pump 50 to stop the first pump 50 (#133). At this time, the intake port and the discharge port of the first pump 50 are in communication even when the first pump 50 is stopped. The control unit 60 also transmits an operation command to the second pump 55 to operate the second pump 55 (#134). As a result, the cooling liquid stored in the tank 30 flows to the battery case 10 via the fourth communication passage 32 and the fourth flow passage 27. The control unit 60 may end the third state based on, for example, a water level sensor that detects the water level of the cooling liquid in the battery case 10 or a water level sensor that detects the water level of the cooling liquid in the tank 30.

In this configuration, since the exhaust port 10E of the battery case 10 is provided on the bottom side, the coolant accumulates in the first flow path 21, the second flow path 22, the heat exchanger 15, and the third flow path 26 when the second pump 55 is driven, and then the level of the coolant in the battery case 10 rises. Even with this configuration, it is possible to increase the amount of coolant in the circulation path 2, but if you want to quickly increase the level of the coolant in the battery case 10 in response to the drive of the second pump 55, for example, it is recommended to provide a valve at the exhaust port 10E of the battery case 10 and close the valve.

The above configuration makes it possible to continuously adjust the level of the coolant in the battery case 10. Therefore, for example, it is possible to detect the temperature of the battery cells 11 and the temperature of the coolant to estimate the heat generation status (heat generation degree) of the battery cells 11, and to immerse the battery cells 11 in the liquid according to the heat generation status of the battery cells 11 based on the estimated results.

2. Second embodiment Next, a second embodiment of the cooling system 1 will be described. In the above-mentioned first embodiment, the tank 30 is arranged in parallel with the heat exchanger 15 in the circulation path 2 via the first valve device 40 and the third communication passage 31, and the second valve device 45 and the fourth communication passage 32. However, in the second embodiment, the tank 30 is not arranged in parallel with the heat exchanger 15 in the circulation path 2 via the first valve device 40 and the third communication passage 31, and the second valve device 45 and the fourth communication passage 32. In the following, the second embodiment will be described focusing on the points different from the first embodiment, and the points similar to the first embodiment will not be described.

Figure 5 is a block diagram showing the configuration of the cooling system 1 of the second embodiment. As shown in Figure 2, the cooling system 1 of this embodiment is configured to include a battery case 10, a heat exchanger 15, a first communication passage 20, a second communication passage 25, a tank 30, a first valve device 40, a first pump 50, a second pump 55, and a control unit 60. The battery case 10, the heat exchanger 15, the first communication passage 20, and the second communication passage 25 are the same as those of the first embodiment, so their description will be omitted.

In this embodiment, the tank 30 is also configured to store the coolant. When the water level in which the battery cells 11 are immersed in the battery case 10 is lowered, the tank 30 stores the coolant and reduces the amount of coolant flowing through the circulation path 2, which includes the battery case 10, the heat exchanger 15, the first communication path 20, and the second communication path 25. On the other hand, when the water level in which the battery cells 11 are immersed in the battery case 10 is raised, the tank 30 discharges the coolant and increases the amount of coolant flowing through the circulation path 2, which includes the battery case 10, the heat exchanger 15, the first communication path 20, and the second communication path 25.

In this embodiment, the first valve device 40 is also provided in the first communication passage 20. In this embodiment, a three-way valve having three communication holes is used for the first valve device 40. Of the three communication holes, two are provided in communication with the first communication passage 20, and the remaining communication hole is connected to the tank 30 via the fifth communication passage 35. In this embodiment, the first valve device 40 also provides communication between the battery case 10 and the heat exchanger 15 in the first communication state, and provides communication between the battery case 10 and the tank 30 in the second communication state.

In this embodiment, the tank 30 is arranged to communicate with the circulation path 2 via the first valve device 40 and the fifth communication passage 35. That is, the tank 30 is arranged to be able to communicate with the battery case 10 only via the first valve device 40.

The first pump 50 is provided in the second communication passage 25 and circulates the coolant between the battery case 10 and the heat exchanger 15.

The second pump 55 is provided in the fifth communication passage 35, and in the second communication state, is configured to be able to supply coolant to the tank 30 and discharge coolant from the tank 30. Therefore, the second pump 55 is capable of circulating coolant in both directions, and is used to supply and discharge coolant in the tank 30.

The control unit 60 controls the first valve device 40, the first pump 50, and the second pump 55 to switch the state of the cooling system 1 between a first state, a second state, and a third state.

Figure 6 shows an example of the cooling system 1 in the first state. In the first state, the control unit 60 circulates the coolant through the circulation path 2. When the control unit 60 is in the first state, it transmits a first instruction to the first valve device 40 to put the first valve device 40 into the first communication state (#211). As a result, the first flow path 21 and the second flow path 22 connected to the communication hole of the first valve device 40 are communicated with each other, and the valve body 40A of the first valve device 40 rotates so that the first flow path 21 and the second flow path 22 are not communicated with each other and the fifth communication path 35.

The control unit 60 also transmits an operation command to the first pump 50 to operate the first pump 50 (#212). The control unit 60 also transmits a stop command to the second pump 55 to stop the second pump 55 (#213). As a result, the coolant flows from the battery case 10 to the heat exchanger 15 via the first communication passage 20, and flows from the heat exchanger 15 to the battery case 10 via the second communication passage 25, and the coolant circulates through the circulation path 2.

Figure 7 shows an example of the cooling system 1 in the second state. In the second state, the control unit 60 stores the coolant in the tank 30. When the control unit 60 is to be in the second state, the control unit 60 transmits a second instruction to the first valve device 40 to put the first valve device 40 in the second communication state (#221). As a result, the valve body 40A of the first valve device 40 rotates so that the first flow path 21 and the fifth communication path 35 connected to the communication hole of the first valve device 40 are communicated with each other, and the first flow path 21 and the fifth communication path 35 are not communicated with each other.

The control unit 60 also transmits a stop command to the first pump 50 to stop the first pump 50 (#222). The control unit 60 also transmits an operation command to the second pump 55 to operate the second pump 55 so as to rotate along a predetermined first direction (#223). This causes the coolant to flow from the battery case 10 to the tank 30 via the first flow path 21 and the fifth communication path 35 and be stored there. The control unit 60 may end the second state based on, for example, a water level sensor that detects the water level of the coolant in the battery case 10 or a water level sensor that detects the water level of the coolant in the tank 30.

Figure 8 shows an example of the cooling system 1 in the third state. In the third state, the control unit 60 drains the coolant from the tank 30 to increase the amount of coolant in the circulation path 2. When the control unit 60 is in the third state, it transmits a third instruction to the first valve device 40 to put the first valve device 40 in the third communication state (#231). As a result, the second flow path 22 and the fifth communication path 35 connected to the communication hole of the first valve device 40 are communicated with each other, and the valve body 40A of the first valve device 40 rotates so that the second flow path 22 and the fifth communication path 35 are not communicated with each other.

The control unit 60 also transmits a stop command to the first pump 50 to stop the first pump 50 (#232). The control unit 60 also transmits an operation command to the second pump 55 to operate the second pump 55 to rotate along a second direction opposite to the first direction described above (#233). This causes the coolant to flow from the battery case 10 to the tank 30 via the second flow path 22 and the fifth communication path 35 and be stored there. The control unit 60 may end the third state based on, for example, a water level sensor that detects the water level of the coolant in the battery case 10 or a water level sensor that detects the water level of the coolant in the tank 30.

In this embodiment, as in the first embodiment, the level of the coolant in the battery case 10 can be adjusted steplessly. For example, the temperature of the battery cells 11 and the temperature of the coolant can be detected to estimate the heat generation status (heat generation degree) of the battery cells 11, and the battery cells 11 can be immersed in the liquid according to the heat generation status of the battery cells 11 based on the estimated results.

3. Other Embodiments In the above embodiment, the control unit 60 has been described as issuing instructions to operate and stop the first pump 50 and the second pump 55. However, the control unit 60 may be configured not to stop both the first pump 50 and the second pump 55 in any of the first state, the second state, and the third state.

In the above first embodiment, the first pump 50 is provided in the first flow path 21, and the second pump 55 is provided in the fourth flow path 27. However, for example, the second pump 55 may be provided in the fourth communication path 32. Furthermore, in addition to the first pump 50 and the second pump 55, further pumps may be provided.

In the above embodiment, the control unit 60 is described as being capable of switching the state of the cooling system 1 between the first state, the second state, and the third state. However, the cooling system 1 may not be provided with a control unit 60, and for example, a control unit of a system different from the cooling system 1 may be configured to switch between the first state, the second state, and the third state.

In the second embodiment described above, when the control unit 60 is in the third state, the valve body 40A of the first valve device 40 is rotated so that the second flow path 22 and the fifth communication path 35 connected to the communication hole of the first valve device 40 communicate with each other, and the second flow path 22 and the fifth communication path 35 do not communicate with each other. For example, when the control unit 60 is in the third state, the valve body 40A of the first valve device 40 can be rotated so that the first flow path 21 and the fifth communication path 35 connected to the communication hole of the first valve device 40 communicate with each other, and the first flow path 21 and the fifth communication path 35 do not communicate with each other. In this case, the coolant from the tank 30 is introduced into the battery case 10 through the outlet 10E of the battery case 10. Furthermore, in this case, it is possible to provide a check valve in the inlet 10I of the battery case 10 or in the fourth flow path 27 to regulate the flow of cooling liquid from the battery case 10 side to the second pump 55 side.

The present invention can be used in a cooling system that circulates a coolant between a battery case and a heat exchanger.

REFERENCE SIGNS LIST 1: Cooling system 2: Circulation path 10: Battery case 11: Battery cell 15: Heat exchanger 20: First communication passage 25: Second communication passage 30: Tank 40: First valve device 45: Second valve device 50: First pump 55: Second pump 60: Control unit

Claims (5)

a battery case that houses a plurality of battery cells and is supplied with a cooling liquid so that the battery cells can be immersed in the cooling liquid;
a heat exchanger for exchanging heat with the cooling liquid;
a first communication passage through which the coolant can flow from the battery case to the heat exchanger;
a second communication passage through which the coolant can flow from the heat exchanger to the battery case;
A tank capable of storing the cooling liquid;
a first valve device provided in the first communication passage and switchable between a first communication state in which the battery case and the heat exchanger are in a communication state and a second communication state in which the battery case and the tank are in a communication state;
A cooling system comprising: The tank is disposed in parallel with the heat exchanger,
2. The cooling system according to claim 1, further comprising a second valve device provided in the second communication passage and switchable between a third communication state that brings the battery case and the heat exchanger into communication with each other and a fourth communication state that brings the battery case and the tank into communication with each other. The cooling system according to claim 1, wherein the tank is capable of communicating with the battery case only through the first valve device, and the coolant can be supplied and discharged in the second communication state. a first pump that circulates the coolant between the battery case and the heat exchanger;
The cooling system according to claim 2 or 3, further comprising: a second pump that supplies the cooling liquid stored in the tank to the battery case. The cooling system according to any one of claims 1 to 3, further comprising a control unit that can switch between a first state in which the cooling liquid is circulated through a circulation path that includes the battery case, the heat exchanger, the first communication path, and the second communication path, a second state in which the cooling liquid is stored in the tank to reduce the amount of the cooling liquid in the circulation path, and a third state in which the cooling liquid is discharged from the tank to increase the amount of the cooling liquid in the circulation path.

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