Cooling system

Abstract

The cooling system disclosed herein enables the determination of the water level using a simple sensor configuration. [Solution] The cooling system comprises a battery pack containing battery modules, an intake duct and an exhaust duct connected to the battery pack, a blower positioned in the path from the intake duct to the exhaust duct, a predetermined sensor for detecting values ​​related to the cooling of the battery pack, a storage unit that stores relationship information between the sensor's detected values ​​and the battery pack's cooling capacity, and a processing unit that determines the water ingress level based on the relationship information and the sensor's detected values.

Description

[Technical Field]

[0001] This disclosure relates to a cooling system. [Background technology]

[0002] Patent Document 1 discloses a cooling system that detects when a battery housed in a waterproof case becomes submerged in water. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-171176 [Overview of the project] [Problems that the invention aims to solve]

[0004] Prior art enables battery water ingress detection by determining the blockage state of the duct through threshold settings of detected values ​​such as fan speed or blower power consumption, which can be detected by a sensor. However, while it can determine whether the duct is completely or partially blocked, there is room for improvement in determining the degree of blockage (i.e., the level of water ingress) in stages.

[0005] This disclosure aims to provide a cooling system that enables the determination of water ingress levels using a simple sensor configuration. [Means for solving the problem]

[0006] The cooling system described in claim 1 comprises a battery pack housing a battery module, an intake duct and an exhaust duct connected to the battery pack, a blower positioned in the path from the intake duct to the exhaust duct, a predetermined sensor for detecting a value related to the cooling of the battery pack, a storage unit that stores relationship information between the sensor's detected value and the battery pack's cooling capacity, and a processing unit that determines the water inundation level based on the relationship information and the sensor's detected value. This enables the determination of the water inundation level with a simple sensor configuration.

[0007] The cooling system according to claim 2 is the cooling system according to claim 1, wherein the sensor is a pressure sensor installed in at least one of the battery pack, the intake duct, and the exhaust duct, the relational information is a relational map showing the relationship between the detected value, which is the rotational speed of the blower, and the pressure loss related to the cooling capacity, and the processing unit determines the water inundation level based on the relational map and the detected value of the pressure sensor. The cooling system according to claim 2 makes it possible to determine the water inundation level with a simple pressure sensor configuration.

[0008] The cooling system according to claim 3 is the cooling system according to claim 1, wherein the sensor is a temperature sensor installed in the battery pack, the relationship information is a relationship map showing the relationship between the detected value, which is the temperature of the battery pack, and the water ingress level with respect to the rate of decrease in cooling performance, and the processing unit determines the water ingress level based on the rate of decrease in cooling performance calculated from the relationship map based on the detected value of the temperature sensor. The cooling system according to claim 3 enables the detection of a decrease in cooling performance and the determination of the water ingress level with a simple temperature sensor configuration.

[0009] The cooling system according to claim 4 is the cooling system according to claim 3, wherein the temperature sensor includes a first temperature sensor that detects a first temperature which is the inlet temperature of the battery pack, and a second temperature sensor that detects a second temperature which is the battery temperature of the battery module. The processing unit acquires a first cooling amount before performance degradation using the first and second temperatures before performance degradation, calculates a second cooling amount based on the operating temperature using the time change of the second temperature detected during operation, calculates the percentage of cooling performance degradation based on the ratio of the first cooling amount to the second cooling amount, and determines the water ingress level. The cooling system according to claim 4 enables the detection of cooling performance degradation and determination of the water ingress level with a simple temperature sensor configuration. [Effects of the Invention]

[0010] The technology disclosed herein enables the determination of flood levels using a simple sensor configuration. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows the configuration of the cooling system according to the first embodiment. [Figure 2] Figure 2 is an example of a graph showing a relationship map. [Figure 3] Figure 3 is an example of a graph showing a relationship map. [Figure 4] Figure 4 shows an example of the time variation of rotation speed and pressure when determining the flood level. [Figure 5] Figure 5 is a flowchart illustrating the processing flow of the processing device 110 in this embodiment. [Figure 6] Figure 6 shows an example configuration when a pressure sensor is installed in the intake duct. [Figure 7] Figure 7 shows the configuration of the cooling system according to the second embodiment. [Figure 8] Figure 8 is a graph showing an example of comparing various detected values ​​related to the battery with and without water ingress. [Figure 9]FIG. 9 is a graph showing an example of comparing the relationships of heat generation amount, cooling amount, and temperature before and after performance degradation.

Embodiments for Carrying Out the Invention

[0012] An overview of an embodiment of the present invention will be described. Conventionally, as described above, for an in-vehicle battery, water immersion detection was performed by determining a threshold value of a detected value, but there were problems with detecting the water immersion level. Also, conventionally, when installing a sensor for detecting water immersion itself, it was necessary to add a plurality of components for water immersion detection and provide sensors for detecting water at a plurality of positions, resulting in a problem of an increase in the cost related to the installation of the sensors. Therefore, in an embodiment of the present invention, a cooling system that enables determination of the water immersion level without using a sensor for detecting water itself is proposed.

[0013] In an embodiment of the present invention, a method for determining the water immersion level using a relationship map related to the cooling capacity of the battery pack, using the pressure or temperature related to the battery pack, which is a detected value related to the cooling of the battery pack detected by a predetermined sensor, is used. Hereinafter, it will be described separately in the first embodiment and the second embodiment.

[0014] (First Embodiment) FIG. 1 is a diagram showing the configuration of a cooling system 10 according to the first embodiment. As shown in FIG. 1, the cooling system 10 includes a battery pack 100 in which a battery module 100a is housed, an intake duct 102 and an exhaust duct 104 connected to the battery pack, a blower 106, a pressure sensor 108, and a processing device 110. The processing device 110 is connected to the pressure sensor 108 and functionally includes a storage unit 120 and a processing unit 122.

[0015] The processing unit 110 is implemented as a computer including a CPU (Central Processing Unit), ROM (Read Only Memory) which stores programs for realizing various processes, RAM (Random Access Memory) which temporarily stores data, memory as a storage means, and a network interface.

[0016] As a premise, the cooling system 10, which is an on-board cooling mechanism, blows cool air from the vehicle interior to the battery pack 100 to cool the battery module 100a itself. The cooling system 10 has an intake duct 102 and a blower 106 for blowing air. In the exhaust duct 104 (or intake duct 102), water ingress changes the airflow through the air vents. Furthermore, this change in airflow causes a change in pressure loss. In this embodiment, the water ingress level is determined based on this principle.

[0017] The airflow through the air vents of the exhaust duct 104 changes depending on the level of flooding. In this embodiment, the level of flooding is assumed to be in stages from Level 0 to Level 4. The example in Figure 1 shows the correspondence between the level of flooding in stages from Level 0 to Level 4 and each air vent of the exhaust duct 104.

[0018] The memory unit 120 stores a relationship map as relational information, which shows the characteristics of the relationship between the rotational speed of the blower 106 and the pressure loss related to the cooling capacity. The relationship map stores predefined pressure thresholds for rotational speed at different immersion levels.

[0019] Figures 2 and 3 are examples of graphs showing relationship maps. The graph in Figure 2 shows the relationship between the immersion level and pressure loss and airflow (PQ characteristics), with the vertical axis representing pressure loss and the horizontal axis representing airflow. The pressure loss curves from Level 0 to Level 4 are shown as an example of the change in the characteristics of the relationship map. In principle, the higher the immersion level, the greater the pressure when operating at the same rotational speed. The graph in Figure 3 shows the relationship map between the rotational speed of blower 106 and pressure, and is a relationship map from Figure 2 with airflow replaced by rotational speed and pressure loss replaced by pressure. The graph in Figure 3 shows the relationship between the immersion level and pressure and rotational speed, with the vertical axis representing pressure and the horizontal axis representing the rotational speed of blower 106. In Figure 3, it is shown that pressure and rotational speed are proportional to the change in immersion level.

[0020] When the rotational speed of the blower 106 exceeds a certain level, the processing unit 122 determines the water level based on the relationship map and the value detected by the pressure sensor 108. In the first embodiment, the detected values ​​are the rotational speed and pressure of the blower 106.

[0021] Figure 4 shows an example of the time variation of rotation speed and pressure when determining the flood level. Figure 4(a) shows the time variation of rotation speed, and (b) shows the time variation of pressure. The rotation speed becomes constant after stable operation, while the pressure changes depending on the flood level. In this embodiment, the determination is made within a stable time (t1) of rotation speed. As shown in (b), the pressure increases as the flood level rises, so the flood level can be determined by the threshold value for each flood level and the detected pressure value, which are defined in advance in the relationship map. The solid line (b1) shows the pressure at the base Level 0 state, and the dotted lines (b2) to (b4) show the pressure at the flood levels of Level 1 to Level 3. The pressure threshold corresponding to the flood level is set to the value corresponding to the pressure shown by the dotted line.

[0022] (Control flow) Figure 5 is a flowchart illustrating the processing flow of the processing device 110 in this embodiment. The following processes should be performed periodically after the blower 106 has started operating.

[0023] In step S100, the processing unit 122 determines whether the rotational speed obtained from the blower 106 is stable. Stable operation can be determined by whether a rotational speed above a certain level has been maintained for a certain period of time or longer. If it is determined that stable operation has occurred, the process proceeds to step S102; if it is determined that stable operation has not occurred, this step is repeated.

[0024] In step S102, the processing unit 122 obtains the detected pressure value from the pressure sensor 108 and the relationship map from the storage unit 120.

[0025] In step S104, the flood level is determined based on the relationship map and the detected value of the pressure sensor 108.

[0026] (Modified version of the first embodiment) The pressure sensor 108 may be installed not only on the battery pack 100, but also on the upstream intake duct 102 or the downstream exhaust duct 104. Figure 6 shows an example configuration when the pressure sensor 108 is installed on the intake duct 102. Note that for the sake of explanation, Figure 6 schematically illustrates only some of the components necessary for the explanation. The same configuration can be used when the pressure sensor 108 is installed on the exhaust duct 104.

[0027] As described above, in the first embodiment, a pressure relationship map is used to enable the determination of the flood level with a simple pressure sensor configuration.

[0028] (Second Embodiment) While the first embodiment uses a relationship map related to pressure, the second embodiment uses a relationship map related to temperature. The principle of the second embodiment will now be explained. As explained in the first embodiment, the higher the water level, the greater the pressure when operating at the same rotational speed. As the pressure rises, the airflow decreases. When the airflow decreases, the cooling performance decreases. As the cooling performance decreases, the temperature rises. Based on the above principle, the second embodiment utilizes a temperature sensor.

[0029] Figure 7 shows the configuration of the cooling system 12 of the second embodiment. As shown in Figure 7, the cooling system 12 comprises a battery pack 100 housing a battery module 100a, an intake duct 102 and an exhaust duct 104 connected to the battery pack, a blower 106, a temperature sensor 208, and a processing unit 110. The processing unit 110 is connected to the temperature sensor 208 and functionally comprises a storage unit 120 and a processing unit 122. The temperature sensor 208 includes a first temperature sensor 208a that detects a first temperature, which is the inlet temperature (intake temperature) of the battery pack 100, and a second temperature sensor 208b that detects a second temperature, which is the battery temperature of the battery module 100a. In the second embodiment, the detected values ​​are the first temperature and the second temperature. In addition, the battery load of the battery pack 100 is acquired by an arbitrary sensor (not shown).

[0030] The memory unit 120 stores a relationship map as related information, which shows the relationship between the water ingress level and the rate of cooling performance degradation between the first cooling amount before performance degradation and the second cooling amount based on the operating temperature. It also stores the derivation formulas for the first cooling amount and the second cooling amount.

[0031] The processing unit 122 pre-acquires the first cooling amount before performance degradation. The first cooling amount is calculated in advance using the first and second temperatures. The acquired first cooling amount is stored in the storage unit 120.

[0032] The method for calculating the first cooling amount will be explained. For the calculation, the internal resistance RI, heat capacity C, cooling coefficient Kf, and blower qN characteristics are obtained in advance. The blower qN characteristics are values ​​proportional to the airflow and rotational speed. Furthermore, the first temperature Tc and second temperature Tb before performance degradation are obtained.

[0033] First, regarding the relationship between the cooling coefficient Kf and the airflow rate q, the cooling amount (QC) is obtained using the following equation (1). QC = Kf·q(Tb-Tc) ···(1) The cooling coefficient Kf is defined as Kf = RI^2 / q(Tb-Tc). First cooling volume QC before performance degradation T(Kf) This is calculated as the sum between the predetermined period T1 and T2 using the following formula (2). QC T(Kf) =ΣQC =Σ(Kf / q(Tb-Tc)) ···(2)

[0034] The processing unit 122 calculates a second cooling amount based on the operating temperature and calculates the percentage of cooling performance degradation based on the ratio of the first cooling amount to the second cooling amount. The processing unit 122 determines the flood level by comparing it with the flood level in the relationship map corresponding to the calculated percentage.

[0035] Figure 8 is a graph showing an example of comparing various detected values ​​related to a battery with and without water ingress. In each graph, the vertical axis shows battery load (A), battery heat generation (B), battery cooling (C), and battery temperature (D), respectively, and the horizontal axis is time. (a1) No water ingress, (a2) Water ingress. In the case of water ingress, (a2)-C shows that the amount of cooling decreases according to the level of water ingress. In the case of water ingress, (a2)-D shows that the amount of cooling decreases and the temperature rises according to the level of water ingress.

[0036] Fig. 9 is a graph showing an example when comparing the relationships of heat generation amount, cooling amount, and temperature before and after performance degradation. (b1) is before performance degradation, and (b2) is after performance degradation. In each graph, the vertical axis represents the heat generation amount (E), the cooling amount (F), and the battery temperature / inlet temperature (G) respectively, and the horizontal axis is time in all cases. In the example, the time points of T1 and T2 are shown respectively. Compared with before performance degradation, the cooling amount decreases after performance degradation. Also, regarding the temperature, it can be seen that the inlet temperature Tc does not decrease, while the battery temperature Tb decreases.

[0037] The calculation method of the second cooling amount will be described. The second cooling amount is calculated based on the rise in battery temperature. Define the temperature rise of Tb from the time point of T1 to T2 as ΔT = Tb2 - Tb1.

[0038] The heat generation amount QH is calculated by QH = R·I^2. The heat generation amount QH from T1 to T2 T is calculated by the following formula (3). QH T = ΣQH = Σ(R·I^2) ···(3)

[0039] The temperature rise of the battery is obtained by ΔT = 1 / C(QH T - QC T ). By formula transformation, the second cooling amount QC T(ΔT) is, QC T(ΔT) = QH T - ΔT·C and is transformed.

[0040] The processing unit 122 calculates the ratio of performance degradation of the cooling amount using the first cooling amount QC T(Kf) and the second cooling amount QC T(ΔT) by the following formula (4). The ratio of performance degradation of the cooling amount = QC T(ΔT) / QC T(Kf) ···(4)

[0041] Table 1 is an example of a relationship map showing the relationship between the ratio of performance degradation and the immersion level.

Table 1

[0042] The flow of the second embodiment can be implemented by replacing the flow of the first embodiment shown in Figure 5. In step S100, the processing unit 122 acquires the first cooling amount before performance degradation. In step S102, the processing unit 122 calculates the second cooling amount based on the operating temperature and calculates the percentage of cooling performance degradation based on the ratio of the first cooling amount to the second cooling amount. In step S104, the processing unit 122 determines the flood level by comparing it with the flood level in the relationship map corresponding to the calculated percentage.

[0043] As described above, in the second embodiment, a relationship map related to temperature is used to enable the determination of the flood level with a simple temperature sensor configuration.

[0044] Furthermore, the various processes that the CPU reads and executes in each of the above embodiments may be executed by various processors other than the CPU. Examples of such processors include PLDs (Programmable Logic Devices) such as FPGAs (Field-Programmable Gate Arrays) whose circuit configuration can be changed after manufacturing, GPUs (Graphics Processing Units), and ASICs (Application Specific Integrated Circuits), which are dedicated electrical circuits that have a circuit configuration specifically designed to execute a particular process. In addition, each of the above processes may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is an electrical circuit that combines circuit elements such as semiconductor elements.

[0045] Furthermore, in the above embodiment, the information processing program was described as being pre-stored (installed) on a non-temporary recording medium that can be read by a computer. For example, the information processing program is pre-stored on ROM or storage. However, it is not limited to this, and each program may be provided in a form recorded on a non-temporary recording medium such as a CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), and USB (Universal Serial Bus) memory. Alternatively, the information processing program may be downloaded from an external device via a network.

[0046] The processing flow described in the above embodiment is just one example, and unnecessary steps may be deleted, new steps added, or the processing order rearranged, as long as it does not deviate from the main point. [Explanation of Symbols]

[0047] 10, 12 Cooling System 100 Battery Pack 100A battery module 102 Intake duct 104 Exhaust duct 106 Blower 108 Pressure Sensor 110 Processing Unit 120 Storage section 122 Processing Unit 208 Temperature Sensor

Claims

1. A battery pack containing a battery module, An intake duct and an exhaust duct connected to the aforementioned battery pack, A blower is positioned in the path from the intake duct to the exhaust duct, A predetermined sensor for detecting a value related to the cooling of the battery pack, A storage unit that stores relationship information between the detected value of the sensor and the cooling capacity of the battery pack, A processing unit that determines the flood level based on the aforementioned related information and the detected value of the sensor, A cooling system equipped with [the following features].

2. The sensor is a pressure sensor installed in at least one of the battery pack, the intake duct, and the exhaust duct. The aforementioned relationship information is a relationship map showing the relationship between the detected value, which is the rotational speed of the blower, and the pressure loss related to the cooling capacity. The cooling system according to claim 1, wherein the processing unit determines the immersion level based on the relationship map and the detected value of the pressure sensor.

3. The sensor is a temperature sensor installed in the battery pack. The aforementioned relationship information is a relationship map showing the relationship between the temperature of the battery pack, which is the detected value, and the water level with respect to the rate of decrease in cooling performance. The cooling system according to claim 1, wherein the processing unit determines the water ingress level based on the percentage of cooling performance degradation calculated from the relationship map based on the temperature sensor's detected value.

4. The temperature sensor includes a first temperature sensor that detects a first temperature which is the inlet temperature of the battery pack, and a second temperature sensor that detects a second temperature which is the battery temperature of the battery module. The cooling system according to claim 3, wherein the processing unit pre-acquires a first cooling amount before performance degradation using the first and second temperatures before performance degradation, calculates a second cooling amount based on the operating temperature using the time change of the second temperature detected during operation, calculates the percentage of cooling performance degradation based on the ratio of the first cooling amount to the second cooling amount, and determines the water ingress level.

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