Battery system

Abstract

The invention relates to a battery system. A case constituting the outer shape of a second cooler disposed between the battery cells and housing therein a second fluid having a lower thermal conductivity than the first fluid is configured from a buffer member capable of expanding and contracting in accordance with the flow rate of the second fluid in the case. The flow rate of the second fluid supplied to the second cooler is increased compared to when the temperature of the battery cell is lower than the threshold value.

Description

Technical Field

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

[0002] The following Japanese patent table 2022-550024 discloses a battery module, which includes a battery cell stack formed by stacking a plurality of pouch-type battery cells, a module frame for accommodating the battery cell stack, and a shell of a radiator connected to the lower part of the module frame. The upper surface of the shell of the radiator is open, and a space is formed between the inner surface of the shell and the bottom surface of the module frame. The radiator is connected to a refrigerant pipeline for circulating the refrigerant. Therefore, the refrigerant flows in the space formed between the inner surface of the shell and the bottom surface of the module frame.

[0003] Furthermore, a plurality of partitions formed of a shape memory alloy are provided on the inner surface of the radiator. A flow path for the refrigerant is formed in the above-mentioned space through each partition. Therefore, the flow path formed in the above-mentioned space changes due to deformation of each partition according to the temperature. Therefore, the temperature of the high-temperature portion is relatively greatly reduced by the refrigerant flowing in the flow path. Summary of the invention

[0004] In the battery module of Japanese Patent Application No. 2022-550024, when thermal linkage occurs between battery cells, it is difficult to suppress the thermal linkage.

[0005] Moreover, in the above-mentioned Japanese Patent Table 2022-550024, the above-mentioned flow path is changed by deforming the partition wall portion formed of a shape memory alloy according to temperature. However, it is difficult to quickly change the flow path according to temperature changes. Therefore, the battery module of the above-mentioned Japanese Patent Table 2022-550024 has low responsiveness to temperature changes of each battery cell.

[0006] The present invention has been made in consideration of the above-mentioned facts, and an object of the present invention is to obtain a battery system which can suppress thermal linkage between battery cells and has good responsiveness to temperature changes of the battery cells.

[0007] The battery system of Option 1 has:

[0008] a plurality of battery cells;

[0009] a first cooler disposed between the battery cells and containing a first fluid including at least one of a gas and a liquid;

[0010] a second cooler disposed between the battery cells and containing a second fluid having a lower thermal conductivity than the first fluid; and

[0011] 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,

[0012] The shell constituting the outer shape of the second cooler is composed of a buffer member that can expand and contract according to the flow rate of the second fluid in the shell.

[0013] When the temperature of the battery cell is equal to or higher than a predetermined threshold, the control unit increases a flow rate of the second fluid supplied to the second cooler compared to when the temperature of the battery cell is lower than the threshold.

[0014] In the battery system of the first scheme, when the temperature of the battery cell is above a predetermined threshold, the control unit increases the flow rate of the second fluid supplied to the second cooler compared to when the temperature of the battery cell is below the threshold. Therefore, when the temperature of the battery cell is above the threshold, the shell constituting the outer shape of the second cooler after expansion by the second fluid contacts the adjacent battery cell. The thermal conductivity of the second fluid is lower than that of the first fluid. That is, the thermal insulation of the second fluid is higher than that of the first fluid. Therefore, the generation of a thermal chain reaction in which the heat of a battery cell that has become a high temperature above the threshold is transferred to other battery cells is suppressed by the second cooler.

[0015] Furthermore, when the temperature of the battery cell is equal to or higher than a predetermined threshold value, 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 changes in the temperature of the battery cell.

[0016] Furthermore, the casing constituting the outer shape of the second cooler is formed of an expandable and contractible buffer member. Therefore, for example, when a battery cell vibrates, the second cooler can suppress the vibration from being transmitted to other battery cells.

[0017] Furthermore, when the temperature of the battery cell is lower than the threshold, the flow rate of the second fluid supplied to the second cooler decreases, so the second cooler (housing) becomes smaller. Therefore, when the temperature of the battery cell is lower than the threshold, the volume of the second cooler (housing) can be reduced.

[0018] Furthermore, since the first fluid is supplied to the first cooler by the control unit, the heat generated by the battery cell can be absorbed by the first cooler. That is, the battery system of the first aspect can achieve both cooling and heat insulation of the battery cell.

[0019] The battery system of Option 2 has:

[0020] a first pipe connected to the first cooler and allowing the first fluid to flow therein; and

[0021] The second pipe is connected to the second cooler and allows the second fluid to flow therein.

[0022] According to the battery system of the second aspect, the configuration for realizing supply and discharge of the first fluid to and from the first cooler and supply and discharge of the second fluid to and from the second cooler can be realized with a simple configuration.

[0023] The battery system of Option 3 has:

[0024] a first pump controlled by the control unit to generate a force capable of supplying the first fluid to the first cooler and discharging the first fluid from the first cooler; and

[0025] The second pump is controlled by the control unit to generate a force capable of supplying the second fluid to the second cooler and discharging the second fluid from the second cooler.

[0026] The battery system of the third aspect can realize the configuration for realizing the supply and discharge of the first fluid to and from the first cooler and the supply and discharge of the second fluid to and from the second cooler with a simple configuration.

[0027] In the battery system of the fourth embodiment,

[0028] The first pipe and the second pipe are part of a circulation system that circulates the first fluid and the second fluid.

[0029] The battery system according to the fourth aspect can circulate the first fluid supplied to the first cooler and the second fluid supplied to the second cooler.

[0030] In the battery system of the fifth embodiment,

[0031] The second fluid is a gas.

[0032] In the battery system of the fifth aspect, there is little possibility that a short circuit will occur in the battery cell due to the second fluid.

[0033] As described above, the battery system according to the present invention has the excellent effect of being able to suppress thermal linkage between battery cells and having good responsiveness to temperature changes of the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like symbols represent like elements.

[0035] Figure 1 is an overall configuration diagram of a battery system according to an embodiment;

[0036] Figure 2 yes Figure 1 A cross-sectional view of the battery module shown along the arrow line 2-2;

[0037] Figure 3 When the temperature of the battery cell exceeds the threshold value Figure 2 Same cross-section view;

[0038] Figure 4 yes Figure 1 A control block diagram of the control device shown;

[0039] Figure 5 is a functional block diagram of the control device;

[0040] Figure 6 This is a flowchart showing the processing executed by the CPU of the control device. DETAILED DESCRIPTION

[0041] Hereinafter, with reference to the accompanying drawings, embodiments of the battery system according to the present invention will be described. Figure 1 Arrow FR shown in the figure as appropriate indicates the front side, arrow LH indicates the left side, and arrow UP indicates the upper side.

[0042] Figure 1 The battery system 10 shown is mounted on a vehicle such as a BEV (Battery Electric Vehicle) or an HEV (Hybrid Electric Vehicle). However, the battery system 10 may be mounted on a device different from the vehicle.

[0043] like Figure 1 As shown, the 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 .

[0044] like Figure 2 and Figure 3 As shown, Figure 1 The battery module 20 shown includes a battery case 21 , a plurality of battery cells 23 , a plurality of first coolers 28 , and a plurality of second coolers 32 .

[0045] The battery case 21 is a hollow body in a rectangular parallelepiped shape. A plurality of battery cells 23 are provided inside the battery case 21. The battery cells 23 of the present embodiment are pouch-type (laminated) lithium-ion secondary batteries. Each battery cell 23 is accommodated inside the battery case 21 in a state of being arranged in the left-right direction. Moreover, each battery cell 23 is electrically connected to each other.

[0046] like Figure 2and Figure 3 As shown, in the following description, each battery cell 23 is sometimes referred to as 23-1, 23-2, 23-3, 23-4, 23-5...23-n-1, 23-n, 23-n+1 in sequence from the right side. In addition, n is a natural number greater than 1. 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. The first shell 29 constituting the outer shape of each first cooler 28 is in the shape of a rectangular parallelepiped. The first shell 29 is made of a watertight material. The first shell 29 can maintain its own shape as long as a large external force is not applied. The first shell 29 is formed of a material with good thermal conductivity. For example, the first shell 29 is made of metal. The left and right side surfaces of each first shell 29 are in contact with the side surfaces of the adjacent battery cells 23.

[0047] like Figure 2 and Figure 3 As shown, the second cooler 32 is provided between the battery cell 23-2 and the battery cell 23-3, between the battery cell 23-4 and the battery cell 23-5, and between the battery cell 23-n and the battery cell 23-n+1. The second shell (shell) (buffer member) 33 constituting the outer shape of the second cooler 32 is made of a flexible and airtight material. That is, the second shell can expand and contract. The thermal conductivity of the second shell 33 is lower than that of the first shell 29.

[0048] like Figure 1 As shown, 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 are connected to the first tank 41 in a watertight state. The other end of the pipe 42 and the pipe 43 are connected to the battery case 21. The other end of the pipe 42 branches inside the battery case 21, and each branch is connected to the first cooler 28 (first case 29) in a watertight state (illustration omitted). The other end of the pipe 43 branches inside the battery case 21, and each branch is connected to the first case 29 in a watertight state (illustration omitted). The first electric pump 44 is connected to the middle part of the pipe 43. In addition, the first fluid 45 (refer to Figure 1 ). When the first electric pump 44 is operated, the first fluid 45 flows along the first tank 41, the pipe 42, the first shells 29 and the pipe 43 by the force generated by the first electric pump 44. Figure 1The pipe 43 circulates in the direction of arrow A1. Moreover, the middle 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. Moreover, a pressure sensor 47 is provided in the pipe 43. The pressure sensor 47 detects the pressure (Pa) of the first fluid 45 flowing inside the pipe 43.

[0049] like Figure 1 As shown, 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 are connected to the second tank 51 in an airtight state. The other end of the pipe 52 and the pipe 53 are connected to the battery case 21. The other end of the pipe 52 branches inside the battery case 21, and each branch is connected to the second cooler 32 (second case 33) in an airtight state (illustration omitted). The other end of the pipe 53 branches inside the battery case 21, and each branch is connected to the second case 33 in an airtight state (illustration omitted). 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. In addition, the second fluid 56 is provided inside the second tank 51 (refer to Figure 1 When the second electric pump 54 and the third electric pump 55 are in operation, the second fluid 56 in the second tank 51 flows through the pipe 52, each second housing 33, the pipe 53 and the interior of the second tank 51. Figure 1 circulates in the direction indicated by the arrow A2. The second fluid 56 in the second tank 51 circulates by the force generated by the second electric pump 54 and the third electric pump 55. In addition, a check valve (not shown) is provided inside the piping 52 and the piping 53, so that the second fluid 56 does not flow in the second tank 51, the piping 52 and the piping 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 piping 52 that is closer to the battery module 20 than the second electric pump 54, the second fluid 56 in each second shell 33, and the second fluid 56 in the piping 53 return to the second tank 51. The second fluid 56 in the portion on the battery module 20 side, the second fluid 56 in each second shell 33, and the second fluid 56 in the piping 53 are circulated by the force generated by the third electric pump 55. Figure 1 The second fluid 56 returns to the second tank 51 as shown by the arrow A2. The thermal conductivity of the second fluid 56 is lower than that of the first fluid 45. The second fluid 56 is, for example, air. However, the second fluid 56 may also be a gas different from air. For example, the second fluid 56 may also be nitrogen or carbon dioxide.

[0050] like Figure 1As shown in FIG. 4 , the first electric pump 44, the pressure sensor 47, the second electric pump 54, and the third electric pump 55 are connected to the control device 60. Figure 4 As shown, the control device 60 is configured to include a CPU (Central Processing Unit: processor) (control unit) 61, a ROM (Read Only Memory: read-only memory) 62, a RAM (Random Access Memory: random access memory) 63, a storage device 64, a communication I / F (InterFace: interface) 65, and an input / output I / F 66. The CPU 61, ROM 62, RAM 63, storage device 64, communication I / F 65, and input / output I / F 66 are connected via a bus 67 so as to be able to communicate with each other.

[0051] The CPU 61 is a central processing unit that executes various programs and controls various parts. That is, the CPU 61 reads the program from the ROM 62 or the storage device 64 and executes the program using the RAM 63 as a work area. The CPU 61 controls each component and performs various calculations (information processing) according to the program recorded in the ROM 62 or the storage device 64.

[0052] The ROM 62 stores various programs and various data, including, for example, data related to a threshold pressure described later.

[0053] RAM 63 temporarily stores programs or data as a work area. Storage device 64 is composed of a storage device such as HDD (Hard Disk Drive) or SSD (Solid State Drive), and stores various programs and various data. Communication I / F 65 can communicate with another control device in control device 60 via an external bus.

[0054] like Figure 5 As shown, the control device 60 includes a cooling control unit 601 and a heat insulation control unit 602 as functional components. The cooling control unit 601 and the heat insulation control unit 602 are implemented by the CPU 61 of the control device 60 reading and executing a program stored in the ROM 62.

[0055] The cooling control unit 601 controls the first electric pump 44. That is, the cooling control unit 601 supplies electric power from a fluid control power source (not shown) to the first electric pump 44 to operate the first electric pump 44.

[0056] When the detection value of the pressure sensor 47 is lower than a predetermined threshold pressure, the insulation control unit 602 supplies power from the fluid control power supply to the third electric pump 55 and does not supply it to the second electric pump 54. Therefore, the second electric pump 54 becomes non-operating and the third electric pump 55 becomes operating. When the detection value of the pressure sensor 47 is lower than the threshold pressure, it is estimated that the temperature of all the battery cells 23 is lower than the predetermined threshold. In other words, when the detection value of the pressure sensor 47 is lower than the threshold pressure, it is estimated that all the battery cells 23 are in a normal state. If the second electric pump 54 becomes non-operating and the third electric pump 55 becomes operating, the second shell 33 of each second cooler 32 is substantially in a vacuum state. Therefore, if Figure 2 As shown, the thickness of each second shell 33 becomes smaller. On the other hand, when the detection value of the pressure sensor 47 is above the above-mentioned threshold pressure, the heat insulation control unit 602 supplies the power of the fluid control power supply 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 operation. When the detection value of the pressure sensor 47 is above the threshold pressure, it is estimated that the temperature of at least one battery cell 23 is above the above-mentioned threshold. In other words, when the detection value of the pressure sensor 47 is above the threshold pressure, it is estimated that at least one battery cell 23 is in an abnormal state. If the second electric pump 54 and the third electric pump 55 are in operation, then Figure 2 As shown, the second fluid 56 flows through the pipe 52, each second shell 33, the pipe 53 and the second tank 51. Figure 1 As a result, the thickness of each second housing 33 increases, and each second cooler 32 contacts the adjacent battery cell 23 .

[0057] Next, the processing executed by the CPU 61 of the control device 60 will be described. The CPU 61 sends Figure 6 The processing of the flowchart shown is repeatedly executed.

[0058] In S10 (hereinafter, the step text is omitted), the CPU 61 activates the first electric pump 44. As a result, the first fluid 45 flows along the inside of the first tank 41, the pipe 42, each first housing 29 and the pipe 43. Figure 1 Therefore, each battery cell 23 is cooled by the first fluid 45 . Then, the heat of the first fluid 45 , which has been heated by taking away heat from each battery cell 23 , is absorbed by the heat exchanger 46 .

[0059] When the process of S10 is completed, the CPU 61 proceeds to S11 to obtain the detection value of the pressure sensor 47 from the pressure sensor 47 .

[0060] When the process of S11 is completed, the CPU 61 proceeds to S12 to determine whether the detection value of the pressure sensor 47 is equal to or higher than the threshold pressure.

[0061] If the determination in S12 is negative, the CPU 61 proceeds to S13. That is, if all the battery cells 23 are in a normal state, the CPU 61 proceeds to S13. In S13, the CPU 61 puts the second electric pump 54 into a non-operating state and puts the third electric pump 55 into an operating state.

[0062] 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. Thus, the second fluid 56 supplied to each second housing 33 expands each second housing 33, and each second housing 33 contacts the side surface of the adjacent battery cell 23.

[0063] When the processing of S13 or S14 is completed, the CPU 61 temporarily terminates Figure 6 Flowchart of the process.

[0064] 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 has become equal to or higher than the threshold value 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 lower than the threshold value. Therefore, when the temperature of the battery cell 23 is equal to or higher than the threshold value, the second shell 33 expanded by the second fluid 56 contacts the side surface of the adjacent battery cell 23. The thermal conductivity of the second fluid 56 is lower than that of the first fluid 45. Moreover, the thermal conductivity of the second shell 33 is lower than that of the first shell 29. That is, the thermal insulation of the second fluid 56 is higher than that of the first fluid 45, and the thermal insulation of the second shell 33 is higher than that of the first shell 29. Therefore, the occurrence of a thermal chain reaction in which the heat of the battery cell 23 having a high temperature equal to or higher than the threshold value is transferred to other battery cells 23 is suppressed by the second shell 33 and the second fluid 56.

[0065] 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 battery system 10 has good responsiveness to the temperature change of the battery cell 23 .

[0066] Furthermore, the second housing 33 of the second cooler 32 is made of a flexible material that can expand and contract. That is, the second housing 33 is made of a buffer member. Therefore, for example, when one battery cell 23 vibrates, the second housing 33 can suppress the vibration from being transmitted to other battery cells 23.

[0067] When the temperature of the battery cell 23 is lower than the threshold, the flow rate of the second fluid 56 supplied to the second cooler 32 is reduced, so the second case 33 is reduced. Therefore, when the temperature of the battery cell 23 is lower than the threshold, the volume of the second case 33 can be reduced.

[0068] 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. That is, the battery system 10 can achieve both cooling and heat insulation of the battery cells 23.

[0069] Furthermore, the first fluid supply device 40 and the second fluid supply device 50 are realized with a simple configuration.

[0070] Furthermore, since the second fluid 56 is a gas, even if the second fluid 56 leaks from the pipe 52 in the battery case 21 , the possibility of a short circuit in the battery cell 23 due to the second fluid 56 is low.

[0071] As mentioned above, although the battery system concerning embodiment was demonstrated, it is possible to change design suitably within the range which does not deviate from the summary of this invention.

[0072] For example, a temperature sensor for detecting 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 the temperature sensor.

[0073] In addition, 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 is, the less the amount of the first fluid 45 in the first tank 41 is. 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.

[0074] Furthermore, a temperature sensor for detecting the temperature of the first cooler 28 may be provided in at least one of the first coolers 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 the temperature sensor.

[0075] Any number of second coolers 32 provided in the battery module 20 may be sufficient. For example, the number of second coolers 32 provided in the battery module 20 may be one.

[0076] The first cooler 28 and the second cooler 32 may be provided between two adjacent battery cells 23 .

[0077] The first fluid may be a gas having a higher thermal conductivity than the second fluid. Alternatively, the first fluid may be composed of a liquid and a gas having a higher thermal conductivity than the second fluid.

[0078] 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 .

[0079] When the temperature of the battery cell 23 is lower than the threshold, 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 higher than the threshold is increased compared to when the temperature of the battery cell 23 is lower than the threshold.

[0080] A heat exchanger may be connected to the pipe 52 or the pipe 53 .

Claims

1. A battery system comprising: 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 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, The shell constituting the outer shape of the second cooler is composed of a buffer member that can expand and contract according to the flow rate of the second fluid in the shell. When the temperature of the battery cell is equal to or higher than a predetermined threshold, the control unit increases a flow rate of the second fluid supplied to the second cooler compared to when the temperature of the battery cell is lower than the threshold.

2. The battery system according to claim 1, comprising: a first pipe connected to the first cooler and allowing the first fluid to flow therein; and The second pipe is connected to the second cooler and allows the second fluid to flow therein.

3. The battery system according to claim 1 or 2, comprising: a first pump controlled by the control unit to generate a force capable of supplying the first fluid to the first cooler and discharging the first fluid from the first cooler; and The second pump is controlled by the control unit to generate a force capable of supplying the second fluid to the second cooler and discharging the second fluid from the second cooler.

4. The battery system according to claim 2, 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, The second fluid is a gas.

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