Battery system

Abstract

To provide a battery system having a good responsiveness to a temperature change of a battery cell while suppressing a thermal chain between the batter cells.SOLUTION: A case 33 that is arranged between battery cells 23 and constructs an outer shape of a second cooler 32 housing a second fluid where a thermal conduction ratio is smaller than that of a first fluid inside is constructed of a buffer member which can be expanded or constructed in accordance with a flow amount of the second fluid in the case. A control part increases the flow amount of the second fluid supplied to the second cooler when a temperature of each battery cell is a predetermined threshold value or larger compared with a case where the temperature is less than the threshold value.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a battery system. [Background technology]

[0002] The following Patent Document 1 discloses a battery module including a battery cell stack formed by stacking a number of pouch-type battery cells, a module frame that houses the battery cell stack, and a heat sink case connected to the lower part of the module frame. The top surface of the heat sink case is open, and a space is formed between the inner surface of the case and the bottom surface of the module frame. The heat sink is connected to a refrigerant pipe through which a refrigerant circulates. Therefore, the refrigerant flows through the space formed between the inner surface of the case and the bottom surface of the module frame.

[0003] Furthermore, the heat sink has a plurality of partitions formed of a shape memory alloy on its inner surface. Each partition forms a flow path for the coolant in the space. Therefore, each partition deforms in response to temperature, changing the flow path formed in the space. Therefore, the coolant flowing through the flow path reduces the temperature of the high-temperature point relatively to a large extent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-550024 Summary of the Invention [Problem to be solved by the invention]

[0005] In the battery module of Patent Document 1, when a thermal chain reaction occurs between battery cells, it is difficult to suppress this thermal chain reaction.

[0006] Furthermore, in the above-mentioned Patent Document 1, the flow path is changed by deforming the partition wall formed from a shape memory alloy in response to temperature. However, it is difficult to quickly change the flow path in response to temperature changes. Therefore, the battery module of the above-mentioned Patent Document 1 has low responsiveness to temperature changes of each battery cell.

[0007] In consideration of the above, an object of the present invention is to provide a battery system that can suppress thermal chain reaction between battery cells and has good responsiveness to temperature changes of the battery cells. [Means for solving the problem]

[0008] A first aspect of the battery system includes a plurality of battery cells, a first cooler arranged between the battery cells and containing a first fluid including at least one of a gas and a liquid, a second cooler arranged between the battery cells and containing a second fluid having a lower thermal conductivity than the first fluid, and a control unit that controls the supply of the first fluid to the first cooler and the discharge of the first fluid from the first cooler, and the supply of the second fluid to the second cooler and the discharge of the second fluid from the second cooler, wherein a case that forms the outer shape of the second cooler is made of a cushioning material that can expand and contract according to a flow rate of the second fluid within the case, and the control unit increases the flow rate of the second fluid supplied to the second cooler when the temperature of the battery cells is equal to or higher than a predetermined threshold value compared to when the temperature is below the threshold value.

[0009] In the battery system of the first aspect, the control unit increases the flow rate of the second fluid supplied to the second cooler when the temperature of the battery cell is equal to or higher than a predetermined threshold value, compared to when the temperature is below the threshold value. Therefore, when the temperature of the battery cell is equal to or higher than the threshold value, the case constituting the outer shape of the second cooler expanded by the second fluid comes into contact with the adjacent battery cell. The second fluid has a lower thermal conductivity than the first fluid. In other words, the second fluid has higher insulating properties than the first fluid. Therefore, the second cooler prevents the occurrence of a thermal chain reaction in which heat from one battery cell that has reached a temperature equal to or higher than the threshold value is transferred to other battery cells.

[0010] Furthermore, when the temperature of the battery cell is equal to or higher than a predetermined threshold, the flow rate of the second fluid supplied to the second cooler increases. Therefore, the battery system of the first aspect has good responsiveness to temperature changes of the battery cell.

[0011] Furthermore, the case that defines the outer shape of the second cooler is made of a shock-absorbing material that can expand and contract. Therefore, for example, when a battery cell vibrates, the second cooler can prevent this vibration from being transmitted to other battery cells.

[0012] Furthermore, when the temperature of the battery cell is below the threshold, the flow rate of the second fluid supplied to the second cooler is reduced, and the second cooler (case) is made smaller. Therefore, when the temperature of the battery cell is below the threshold, the volume of the second cooler (case) can be reduced.

[0013] Furthermore, since the first fluid is supplied to the first cooler by the control unit, the heat generated in the battery cells can be absorbed by the first cooler. That is, the battery system of the first aspect can achieve both cooling and insulation of the battery cells.

[0014] The battery system of a second embodiment includes a first pipe connected to the first cooler and through which the first fluid flows, and a second pipe connected to the second cooler and through which the second fluid flows.

[0015] According to the battery system of the second aspect, a configuration for supplying the first fluid to the first cooler and discharging it from the first cooler, and supplying the second fluid to the second cooler and discharging it from the second cooler can be realized with a simple configuration.

[0016] The battery system of a third aspect includes a first pump controlled by the control unit and generating a force capable of supplying the first fluid to the first cooler and discharging it from the first cooler, and a second pump generating a force capable of supplying the second fluid to the second cooler and discharging it from the second cooler.

[0017] The battery system of the third aspect can achieve, with a simple configuration, the supply of the first fluid to the first cooler and the discharge of the first fluid from the first cooler, and the supply of the second fluid to the second cooler and the discharge of the second fluid from the second cooler.

[0018] In the battery system of a fourth aspect, the first pipe and the second pipe are part of a circulation system that circulates the first fluid and the second fluid.

[0019] In the battery system of the fourth aspect, the first fluid supplied to the first cooler and the second fluid supplied to the second cooler are circulated.

[0020] In a fifth embodiment of the battery system, the second fluid is a gas.

[0021] In the battery system of the fifth aspect, there is a small risk of a short circuit occurring in the battery cell due to the second fluid. Effect of the Invention

[0022] As described above, the battery system according to the present invention has the excellent effects of being able to suppress thermal chain reaction between battery cells, and also having good responsiveness to temperature changes of the battery cells. [Brief description of the drawings]

[0023] [Figure 1] 1 is an overall configuration diagram of a battery system according to an embodiment; [Diagram 2] 2 is a cross-sectional view taken along the line 2-2 of the battery module shown in FIG. 1. [Diagram 3] 3 is a cross-sectional view similar to FIG. 2 when the temperature of the battery cell has reached or exceeded a threshold value. [Figure 4] FIG. 2 is a control block diagram of the control device shown in FIG. [Diagram 5] FIG. 2 is a functional block diagram of a control device. [Figure 6] 4 is a flowchart showing a process executed by a CPU of the control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of a battery system according to the present invention will be described with reference to the accompanying drawings. In the drawings, an arrow FR indicates the front side, an arrow LH indicates the left side, and an arrow UP indicates the up side.

[0025] 1 is mounted on a vehicle, such as a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV). However, the battery system 10 may be mounted on something other than a vehicle.

[0026] As shown in FIG. 1, a battery system 10 includes a battery module 20, a first fluid supply device (circulation system) 40, a second fluid supply device (circulation system) 50, and a control device 60.

[0027] The battery module 20 shown in FIG. 1 includes a battery case 21, a plurality of battery cells 23, a plurality of first coolers 28, and a plurality of second coolers 32, as shown in FIGS.

[0028] The battery case 21 is a hollow body having a rectangular parallelepiped shape. A plurality of battery cells 23 are provided inside the battery case 21. The battery cells 23 in this embodiment are pouch-type (laminated) lithium-ion secondary batteries. The battery cells 23 are stored inside the battery case 21 in a state where they are aligned in the left-right direction. Furthermore, the battery cells 23 are electrically connected to each other.

[0029] As shown in FIG. 2 and FIG. 3, in the following description, the battery cells 23 may be referred to as 23-1, 23-2, 23-3, 23-4, 23-5, . . . 23-n-1, 23-n, 23-n+1 in order from the right side. Here, n is a natural number of 1 or more. A first cooler 28 is provided between the battery cell 23-1 and the battery cell 23-2, between the battery cell 23-3 and the battery cell 23-4, and between the battery cell 23-n-1 and the battery cell 23-n. A first case 29 constituting the outer shape of each first cooler 28 has a rectangular parallelepiped shape. The first case 29 is made of a material having watertightness. The first case 29 can maintain its own shape unless a large external force is applied. The first case 29 is formed of a material having good thermal conductivity. For example, the first case 29 is made of a metal. The left and right side surfaces of each first case 29 are in contact with the side surfaces of the adjacent battery cells 23.

[0030] 2 and 3, second coolers 32 are provided between battery cell 23-2 and battery cell 23-3, between battery cell 23-4 and battery cell 23-5, and between battery cell 23-n and battery cell 23-n+1. A second case (case) (buffer member) 33 that forms the outer shape of the second cooler 32 is made of a flexible and airtight material. That is, the second case is expandable and contractible. The thermal conductivity of the second case 33 is lower than that of the first case 29.

[0031] As shown in FIG. 1, the first fluid supply device 40 includes a first tank 41, a pipe (first pipe) 42, a pipe (first pipe) 43, a first electric pump (first pump) 44, a first fluid 45, a heat exchanger 46, and a pressure sensor 47. One end of the pipe 42 and the pipe 43 is connected to the first tank 41 in a watertight state. The other end of the pipe 42 and the pipe 43 is connected to the battery case 21. The other end of the pipe 42 branches out inside the battery case 21, and each branched part is connected to the first cooler 28 (first case 29) in a watertight state (not shown). The other end of the pipe 43 branches out inside the battery case 21, and each branched part is connected to the first case 29 in a watertight state (not shown). The first electric pump 44 is connected to the middle part of the pipe 43. Furthermore, a first fluid 45 (see FIG. 1) is provided inside the first tank 41, inside the pipe 42, inside the pipe 43, and inside each first case 29. When the first electric pump 44 operates, the force generated by the first electric pump 44 causes the first fluid 45 to circulate inside the first tank 41, the pipe 42, each first case 29, and the pipe 43 in the direction of arrow A1 in FIG. 1. Furthermore, an intermediate portion of the pipe 43 is connected to a heat exchanger 46. When the battery system 10 is mounted on a vehicle, the heat exchanger 46 is, for example, a radiator. Furthermore, the pipe 43 is provided with a pressure sensor 47. The pressure sensor 47 detects the pressure (Pa) of the first fluid 45 flowing inside the pipe 43.

[0032] As shown in FIG. 1, the second fluid supply device 50 includes a second tank 51, a pipe (second pipe) 52, a pipe (second pipe) 53, a second electric pump (second pump) 54, a third electric pump (second pump) 55, and a second fluid 56. One end of the pipe 52 and the pipe 53 is airtightly connected to the second tank 51. The other end of the pipe 52 and the pipe 53 is connected to the battery case 21. The other end of the pipe 52 branches out inside the battery case 21, and each branched part is airtightly connected to the second cooler 32 (second case 33) (not shown). The other end of the pipe 53 branches out inside the battery case 21, and each branched part is airtightly connected to the second case 33 (not shown). The second electric pump 54 is connected to the middle part of the pipe 52, and the third electric pump 55 is connected to the middle part of the pipe 53. Furthermore, a second fluid 56 (see FIG. 1) is provided inside the second tank 51. When the second electric pump 54 and the third electric pump 55 are in operation, the second fluid 56 in the second tank 51 circulates through the inside of the pipe 52, each of the second cases 33, the pipe 53, and the second tank 51 in the direction indicated by the arrow A2 in FIG. 1 by the force generated by the second electric pump 54 and the third electric pump 55. Note that, since check valves (not shown) are provided inside the pipes 52 and 53, the second fluid 56 does not flow inside the second tank 51, the pipes 52, and the pipes 53 in the direction opposite to the direction of the arrow A2. On the other hand, when the second electric pump 54 is in a non-operating state and the third electric pump 55 is in an operating state, the second fluid 56 in the portion of the pipe 52 located closer to the battery module 20 than the second electric pump 54, the second fluid 56 in each second case 33, and the second fluid 56 in the pipe 53 are returned to the second tank 51 by the force generated by the third electric pump 55, as shown by the arrow A2 in FIG. 1. The thermal conductivity of the second fluid 56 is smaller than the thermal conductivity of the first fluid 45. The second fluid 56 is, for example, air. However, the second fluid 56 may be a gas other than air. For example, the second fluid 56 may be nitrogen or carbon dioxide.

[0033] As shown in Fig. 1, the first electric pump 44, the pressure sensor 47, the second electric pump 54, and the third electric pump 55 are connected to a control device 60. As shown in Fig. 4, the control device 60 includes a CPU (Central Processing Unit: processor) (controller) 61, a ROM (Read Only Memory) 62, a RAM (Random Access Memory) 63, a storage 64, a communication I / F (Interface) 65, and an input / output I / F 66. The CPU 61, the ROM 62, the RAM 63, the storage 64, the communication I / F 65, and the input / output I / F 66 are connected to each other via a bus 67 so as to be able to communicate with each other.

[0034] The CPU 61 is a central processing unit that executes various programs and controls each part. That is, the CPU 61 reads a program from the ROM 62 or the storage 64, and executes the program using the RAM 63 as a working area. The CPU 61 controls each component and performs various calculation processes (information processing) according to the program recorded in the ROM 62 or the storage 64.

[0035] The ROM 62 stores various programs and various data, including, for example, data relating to a threshold pressure, which will be described later.

[0036] The RAM 63 temporarily stores programs or data as a working area. The storage 64 is configured with a storage device such as a hard disk drive (HDD) or a solid state drive (SSD) and stores various programs and various data. The communication I / F 65 is capable of communicating with a control device other than the control device 60 via an external bus.

[0037] 5, the control device 60 has, as its functional components, a cooling control unit 601 and a heat insulation control unit 602. The cooling control unit 601 and the heat insulation control unit 602 are realized by the CPU 61 of the control device 60 reading and executing a program stored in the ROM 62.

[0038] The cooling control unit 601 controls the first electric pump 44. That is, the cooling control unit 601 supplies power from a fluid control power source (not shown) to the first electric pump 44 to operate the first electric pump 44.

[0039] When the detection value of the pressure sensor 47 is less than a predetermined threshold pressure, the insulation control unit 602 supplies the power of the fluid control power source to the third electric pump 55 and does not supply the power to the second electric pump 54. Therefore, the second electric pump 54 is in an inoperative state and the third electric pump 55 is in an operative state. When the detection value of the pressure sensor 47 is less than the threshold pressure, it is estimated that the temperatures of all the battery cells 23 are less than the predetermined threshold. In other words, when the detection value of the pressure sensor 47 is less than the threshold pressure, it is estimated that all the battery cells 23 are in a normal state. When the second electric pump 54 is in an inoperative state and the third electric pump 55 is in an operative state, the second case 33 of each second cooler 32 is substantially in a vacuum state. Therefore, as shown in FIG. 2, the thickness of each second case 33 is reduced. On the other hand, when the detection value of the pressure sensor 47 is equal to or greater than the threshold pressure, the insulation control unit 602 supplies the power of the fluid control power source to the second electric pump 54 and the third electric pump 55. Therefore, the second electric pump 54 and the third electric pump 55 are in an operating state. When the detection value of the pressure sensor 47 is equal to or higher than the threshold pressure, it is estimated that the temperature of at least one battery cell 23 is equal to or higher than the threshold pressure. In other words, when the detection value of the pressure sensor 47 is equal to or higher than the threshold pressure, it is estimated that at least one battery cell 23 is in an abnormal state. When the second electric pump 54 and the third electric pump 55 are in an operating state, as shown in Fig. 2, the second fluid 56 circulates inside the pipe 52, each second case 33, the pipe 53, and the second tank 51 in the direction indicated by the arrow A2 in Fig. 1, so that the thickness of each second case 33 increases and each second cooler 32 comes into contact with the adjacent battery cell 23.

[0040] Next, a description will be given of the processing executed by the CPU 61 of the control device 60. The CPU 61 repeatedly executes the processing of the flowchart shown in FIG.

[0041] In step S10 (hereinafter, the letter "step" will be omitted), the CPU 61 operates the first electric pump 44. This causes the first fluid 45 to circulate inside the first tank 41, the pipe 42, each of the first cases 29, and the pipe 43 in the direction of arrow A1 in FIG. 1. Therefore, each battery cell 23 is cooled by the first fluid 45. Furthermore, the heat of the first fluid 45, which has been heated by removing heat from each battery cell 23, is absorbed by the heat exchanger 46.

[0042] When the process of S10 is completed, the CPU 61 proceeds to S11, where it obtains the detection value of the pressure sensor 47 from the pressure sensor 47.

[0043] When the process of S11 is completed, the CPU 61 proceeds to S12 and determines whether or not the detection value of the pressure sensor 47 is equal to or greater than the threshold pressure.

[0044] If the determination in S12 is No, the CPU 61 proceeds to S13. That is, when all of the battery cells 23 are in a normal state, the CPU 61 proceeds to S13. In S13, the CPU 61 sets the second electric pump 54 to a non-operating state and sets the third electric pump 55 to an operating state.

[0045] On the other hand, when the determination in S12 is Yes, the CPU 61 proceeds to S14. That is, when at least one battery cell 23 is in an abnormal state, the CPU 61 proceeds to S14. In S14, the CPU 61 activates the second electric pump 54 and the third electric pump 55. Therefore, the second fluid 56 supplied to each second case 33 causes each second case 33 to expand, and each second case 33 comes into contact with the side surface of the adjacent battery cell 23.

[0046] When the process of S13 or S14 is completed, the CPU 61 temporarily ends the process of the flowchart of FIG.

[0047] As described above, in the battery system 10 of the present embodiment, when the CPU 61 determines that the temperature of the battery cell 23 is equal to or higher than the threshold based on the detection value of the pressure sensor 47, the flow rate of the second fluid 56 supplied to the second cooler 32 is increased compared to when the temperature of the battery cell 23 is below the threshold. Therefore, when the temperature of the battery cell 23 is equal to or higher than the threshold, the second case 33 expanded by the second fluid 56 comes into contact with the side of the adjacent battery cell 23. The second fluid 56 has a lower thermal conductivity than the first fluid 45. Furthermore, the thermal conductivity of the second case 33 is lower than that of the first case 29. That is, the second fluid 56 has a higher thermal insulation property than the first fluid 45, and the second case 33 has a higher thermal insulation property than the first case 29. Therefore, the second case 33 and the second fluid 56 prevent the heat of the battery cell 23 that has reached a high temperature equal to or higher than the threshold from being transmitted to another battery cell 23, which is a thermal chain reaction.

[0048] Furthermore, when the temperature of the battery cell 23 is equal to or higher than the threshold value, the flow rate of the second fluid 56 supplied to the second cooler 32 increases. Therefore, the responsiveness of the battery system 10 to temperature changes of the battery cell 23 is good.

[0049] Furthermore, the second case 33 of the second cooler 32 is made of a flexible material that can expand and contract. That is, the second case 33 is made of a cushioning material. Therefore, for example, when one battery cell 23 vibrates, the second case 33 can prevent this vibration from being transmitted to the other battery cells 23.

[0050] Furthermore, when the temperature of the battery cells 23 is below the threshold value, the flow rate of the second fluid 56 supplied to the second cooler 32 is reduced, thereby reducing the size of the second case 33. Therefore, when the temperature of the battery cells 23 is below the threshold value, the volume of the second case 33 can be reduced.

[0051] Furthermore, since the first fluid 45 is supplied to the first cooler 28, the heat generated in the battery cells 23 can be absorbed by the first cooler 28. In other words, the battery system 10 can both cool and insulate the battery cells 23.

[0052] Furthermore, the first fluid supply device 40 and the second fluid supply device 50 are realized with a simple configuration.

[0053] Furthermore, because the second fluid 56 is in a gaseous state, even if the second fluid 56 leaks from the pipe 52 inside the battery case 21, there is little risk of the second fluid 56 causing a short circuit in the battery cell 23.

[0054] Although the battery system according to the embodiment has been described above, the design thereof can be appropriately modified without departing from the scope of the present invention.

[0055] For example, a temperature sensor that detects the temperature of the first fluid 45 may be provided in the pipe 42 or the pipe 43, and the CPU 61 may determine whether the temperature of the battery cell 23 is equal to or higher than a threshold value based on the detection result of this temperature sensor.

[0056] A sensor for measuring the amount of the first fluid 45 in the first tank 41 may be provided inside the first tank 41. The higher the temperature of the first fluid 45, the smaller the amount of the first fluid 45 in the first tank 41. Therefore, in this case, the CPU 61 may determine whether the temperature of the battery cell 23 is equal to or higher than the threshold value based on the detection result of the sensor.

[0057] Furthermore, at least one first cooler 28 may be provided with a temperature sensor that detects the temperature of the first cooler 28, and the CPU 61 may determine whether the temperature of the battery cell 23 is equal to or higher than a threshold value based on the detection result of this temperature sensor.

[0058] Any number of second coolers 32 may be provided in the battery module 20. For example, the number of second coolers 32 provided in the battery module 20 may be one.

[0059] A first cooler 28 and a second cooler 32 may be provided between two adjacent battery cells 23.

[0060] The first fluid may be a gas having a higher thermal conductivity than the second fluid, or the first fluid may be composed of a liquid and a gas having a higher thermal conductivity than the second fluid.

[0061] The second fluid may be a liquid having a lower thermal conductivity than the first fluid. In this case, the second fluid supply device may have the same configuration as the first fluid supply device 40.

[0062] When the temperature of the battery cell 23 is below the threshold value, the second fluid 56 may be supplied to the second cooler 32. However, in this case, the amount of the second fluid 56 supplied to the second cooler 32 when the temperature of the battery cell 23 is equal to or higher than the threshold value is set to be larger than when the temperature of the battery cell 23 is below the threshold value.

[0063] A heat exchanger may be connected to the pipe 52 or the pipe 53 . [Explanation of symbols]

[0064] 10 Battery System 23 Battery Cell 28 1st cooler 32 Second cooler 33 Second case (case) (buffer material) 40 First fluid supply device (circulation system) 42 Piping (1st Piping) 43 Piping (1st Piping) 44 First electric pump (first pump) 45 1st fluid 50 Second fluid supply device (circulation system) 52 Piping (Second piping) 53 Piping (Second piping) 54 Second electric pump (Second pump) 55 3rd electric pump (2nd pump) 56 Second fluid 61 CPU (control unit)

Claims

1. A plurality of battery cells; a first cooler disposed between the battery cells and containing a first fluid including at least one of a gas and a liquid; a second cooler disposed between the battery cells and containing a second fluid therein, the second fluid having a lower thermal conductivity than the first fluid; a control unit that controls the supply of the first fluid to the first cooler and the discharge of the first fluid from the first cooler, and the supply of the second fluid to the second cooler and the discharge of the second fluid from the second cooler; Equipped with a case that defines an outer shape of the second cooler is made of a buffer member that can expand and contract according to a flow rate of the second fluid in the case, The control unit increases the flow rate of the second fluid supplied to the second cooler when the temperature of the battery cell is equal to or higher than a predetermined threshold value, compared to when the temperature is below the threshold value.

2. a first pipe connected to the first cooler and through which the first fluid flows; a second pipe connected to the second cooler and through which the second fluid flows; The battery system according to claim 1 .

3. 3. The battery system according to claim 1, further comprising: a first pump controlled by the control unit and generating a force capable of supplying the first fluid to the first cooler and discharging it from the first cooler; and a second pump generating a force capable of supplying the second fluid to the second cooler and discharging it from the second cooler.

4. The battery system according to claim 2 , wherein the first pipe and the second pipe are part of a circulation system that circulates the first fluid and the second fluid.

5. The battery system according to claim 1 or 2, wherein the second fluid is a gas.

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