Determination device and determination program

Abstract

This determination device (31) for determining the airtightness of a battery pack (11) having a housing (50) that accommodates batteries (20, 21, 22) comprises: a determination unit (32) that acquires detection values from one or a plurality of internal sensors (44a, 45a, 46a, 47) for detecting physical quantities pertaining to the internal state of the housing, and determines the airtightness on the basis of the acquired detection values; and a notification unit (33) that notifies that there is no airtightness when the determination unit determines that there is no airtightness.

Description

Discrimination Device and Discrimination Program Cross-Reference to Related Applications

[0001] This application is based on Japanese Patent Application No. 2024-163847 filed on September 20, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a discrimination device and a discrimination program for discriminating the airtightness of a battery pack.

[0003] Conventionally, a method for discriminating the life of the seal portion of a laminated battery as a battery cell has been known. Such a technique is described in, for example, Patent Document 1.

[0004] Japanese Unexamined Patent Application Publication No. 2023-125685

[0005] In recent years, a battery pack that houses a plurality of such battery cells combined, a battery ECU, a cooling device, various sensors, etc., and is packaged is mounted on a vehicle. In order to ensure the weather resistance of the battery pack, airtightness is required for the battery pack. On the other hand, when the explosion-proof valve of the battery cell is opened and gas is discharged from the battery cell during an abnormality of the battery cell, etc., and the air pressure inside the battery pack rises, in order to avoid rupture of the battery pack, the explosion-proof valve provided in the housing of the battery pack is opened to intentionally reduce the air pressure.

[0006] By the way, since airtightness is required for the battery pack as described above, when the explosion-proof valve of the battery pack is opened, or when a hole is opened in the housing of the battery pack, replacement of the battery pack, etc. becomes necessary. However, at present, there is a problem that a device for detecting whether the airtightness of the battery pack is ensured is not provided in the battery pack, and it is impossible to quickly discriminate whether the airtightness is ensured.

[0007] The main object of the present disclosure is to provide a discrimination device and a discrimination program capable of discriminating the airtightness of a battery pack.

[0008] A discrimination device for solving the above problems is a discrimination device for determining the airtightness of a battery pack having a housing for a battery, comprising: a discrimination unit that acquires detected values ​​from one or more internal sensors that detect physical quantities related to the internal state of the housing, and determines the airtightness based on the acquired detected values; and a notification unit that notifies the user if the discrimination unit determines that the battery pack is not airtight.

[0009] This allows for accurate determination of the battery pack's airtightness.

[0010] A discrimination program that solves the above problem is a discrimination program implemented by a discrimination device that determines the airtightness of a battery pack having a housing for a battery, wherein the discrimination device is made to perform a discrimination step of acquiring detection values ​​from one or more internal sensors that detect physical quantities related to the internal state of the housing, and determining the airtightness based on the acquired detection values, and a notification step of notifying the device if it is determined in the discrimination step that the airtightness is not present.

[0011] This allows for accurate determination of the battery pack's airtightness.

[0012] The above-mentioned objectives and other objectives, features and advantages of this disclosure will become clearer from the following detailed description with reference to the attached drawings. The drawings are as follows: Figure 1 is a schematic diagram showing the overall configuration of the drive system 100; Figure 2 is a plan view showing the internal configuration of the battery pack; Figure 3 is a side view showing the internal configuration of the battery pack; Figure 4 is a block diagram showing an overview of the battery ECU; Figure 5 is a flowchart of the discrimination process of the first embodiment; Figure 6 is a flowchart of the discrimination process of the second embodiment; Figure 7 is a flowchart of the discrimination process of the third embodiment; Figure 8 is a flowchart of the discrimination process of the fourth embodiment; Figure 9 is a flowchart of the discrimination process of the fifth embodiment; Figure 10 is a flowchart of the discrimination process of the sixth embodiment; and Figure 11 is a flowchart of the discrimination process of the seventh embodiment. Figure 12 is a flowchart of the discrimination process of the eighth embodiment, Figure 13 is a flowchart of the discrimination process of the ninth embodiment, Figure 14 is a side view showing the internal configuration of a modified battery pack, Figure 15 is a block diagram showing an overview of the battery ECU of the tenth embodiment, Figure 16 is a side view showing the internal configuration of the battery pack of the tenth embodiment, Figure 17 is a flowchart of the discrimination process of the tenth embodiment, Figure 18 is a flowchart of the discrimination process of a modified example, Figure 19 is a block diagram showing an overview of the battery ECU of a modified example, Figure 20 is a block diagram showing an overview of the battery ECU of a modified example, and Figure 21 is a side view showing the internal configuration of a modified battery pack.

[0013] The embodiments of the battery pack described herein will be described in detail below with reference to the drawings. In principle, the same or corresponding parts in the drawings will be denoted by the same reference numerals and their descriptions will not be repeated between each embodiment and each modification. The following description will focus on applications to vehicles, but the invention is also applicable to other uses, such as drones and other aircraft, ships, construction machinery, and agricultural machinery.

[0014] (First Embodiment) The battery pack 11 of this embodiment is mounted on a vehicle as a power source for the vehicle. The vehicle is an electric vehicle such as an electric vehicle (EV), a hybrid vehicle (HV), or a plug-in hybrid vehicle (PHV). As shown in Figure 1, in addition to the battery pack 11, the vehicle is also equipped with a power control unit 12 and a motor 13. The battery pack 11, power control unit 12, motor 13, etc. constitute the vehicle's drive system 100.

[0015] The battery pack 11 is located, for example, in the front compartment of the vehicle. Alternatively, the battery pack 11 may be located in the rear compartment, under the seats, or under the floor.

[0016] The battery pack 11 includes a battery pack 20 (described later) and is a rechargeable DC voltage source. The battery pack 11 supplies power to various electrical loads of the vehicle (such as the air conditioner). The battery pack 11 also converts power through the power control unit 12 and supplies power to the motor 13. The battery pack 11 is also charged through the power control unit 12.

[0017] The power control unit 12 is configured to include, for example, an inverter that converts the DC voltage from the battery pack 11 into an AC voltage to drive the motor 13, and a converter that boosts the DC voltage supplied to the inverter to an output voltage higher than that of the battery pack 11.

[0018] The motor 13 is an AC rotating electric machine, for example, a three-phase AC synchronous motor with permanent magnets embedded in the rotor. The motor 13 is driven by the power control unit 12 to generate rotational driving force, and the driving force generated by the motor 13 is transmitted to the drive wheels. On the other hand, when the vehicle is braking, the motor 13 operates as a generator and performs regenerative power generation. The electricity generated by the motor 13 is supplied to the battery pack 11 through the power control unit 12 and stored in the battery pack 20.

[0019] The battery pack 11 will now be described in detail. Figure 2 is a schematic plan view showing the internal configuration of the battery pack 11, and Figure 3 is a schematic side view showing the internal configuration of the battery pack 11. Note that in Figure 2, the top portion of the battery pack 11 (the top of the housing case 50) is omitted from the illustration so that the internal arrangement can be seen when viewed from above. Similarly, in Figure 3, the side walls of the battery pack 11 (the side walls of the housing case 50) are omitted from the illustration so that the internal arrangement can be seen when viewed from the side. The battery pack 11 comprises a battery pack 20, a battery ECU 30 as a control device, a microcontroller 31, various sensors 40, and a housing case 50 as an enclosure for housing them. Figure 4 shows a block diagram showing the connection configuration of the battery ECU 30, the microcontroller 31, and the various sensors 40.

[0020] The battery pack 20 has a plurality of battery blocks 21 (sometimes referred to as a battery stack or battery module). The battery pack 20 is formed by connecting these plurality of battery blocks 21 in series and / or in parallel. Each battery block 21 has a plurality of battery cells 22. Each battery cell 22 is made up of a lithium-ion secondary battery, a nickel-metal hydride secondary battery, etc. A lithium-ion secondary battery is a secondary battery that uses lithium as a charge carrier, and may include not only general lithium-ion secondary batteries with a liquid electrolyte, but also so-called all-solid-state batteries that use a solid electrolyte. The battery block 21 is formed by connecting these plurality of battery cells 22 in series and / or in parallel via busbars (not shown). Whether or not to provide battery blocks 21 is optional, and the battery pack 20 may be formed by connecting a plurality of battery cells 22 in series and / or in parallel.

[0021] The battery cell 22 is equipped with an explosion-proof valve (safety valve) that opens to release internal gases and relieve internal pressure when the internal pressure of the battery cell 22 exceeds a predetermined level, thereby preventing the battery cell 22 from rupturing. The explosion-proof valve of the battery cell 22 is referred to as the cell explosion-proof valve 22a. The cell explosion-proof valve 22a is provided, for example, on the top surface of the battery cell 22. In the case of a lithium-ion secondary battery, when the cell explosion-proof valve 22a is opened, gases such as hydrogen, CO2 (carbon dioxide), CO (carbon monoxide), and methane are released.

[0022] The battery ECU 30 is also called a BMU (Battery Management Unit). It is connected to the microcontroller 31 and performs various controls based on information from the microcontroller 31. As shown in Figure 4, the microcontroller 31 is connected to various sensors 40 and is configured to acquire sensor information from the various sensors 40.

[0023] The various sensors 40 include, for example, a voltage sensor 41 for measuring the voltage of the battery cells 22, a temperature sensor 42 for measuring the temperature of the battery cells 22, and a current sensor 43 for measuring the current input and output from the battery cells 22. The sensor information includes, for example, voltage information, temperature information, and current information for each battery cell 22. The target of monitoring by these sensors 41 to 43 may be the battery block 21 or the entire battery pack 20, and this can be changed as needed.

[0024] Furthermore, the various sensors 40 include an internal pressure sensor 44a for measuring the atmospheric pressure (air pressure) inside the storage case 50, and an external pressure sensor 44b for measuring the atmospheric pressure (air pressure) outside the storage case 50. The various sensors 40 also include an internal gas sensor 45a for measuring the concentration of a specific gas inside the storage case 50, and an external gas sensor 45b for measuring a specific gas outside the storage case 50. The various sensors 40 also include an internal humidity sensor 46a for measuring the humidity inside the storage case 50, and an external humidity sensor 46b for measuring the humidity outside the storage case 50. The various sensors 40 also include a light receiving sensor 47 for measuring the amount of light inside the storage case 50.

[0025] In the first embodiment, it is sufficient to have an internal pressure sensor 44a and an external pressure sensor 44b, and it is not necessary to have any or all of the internal gas sensor 45a, external gas sensor 45b, internal humidity sensor 46a, external humidity sensor 46b, and light receiving sensor 47.

[0026] Furthermore, one or all of the internal pressure sensor 44a, internal gas sensor 45a, internal humidity sensor 46a, and light receiving sensor 47 correspond to internal sensors that detect physical quantities related to the internal state (or internal environment) of the housing case 50. The internal pressure sensor 44a, internal gas sensor 45a, internal humidity sensor 46a, and light receiving sensor 47 are arranged at arbitrary positions inside the housing case 50.

[0027] Furthermore, any or all of the external pressure sensor 44b, external gas sensor 45b, and external humidity sensor 46b correspond to external sensors that detect physical quantities related to the external state (or external environment) of the housing case 50. The external pressure sensor 44b, external gas sensor 45b, and external humidity sensor 46b are arranged at any position outside the housing case 50. For example, they may be provided on the surface of the housing case 50. Also, in the following description, when simply referred to as "internal," it generally refers to the inside of the housing case 50 (the inside of the battery pack 11). Similarly, when simply referred to as "external," it generally refers to the outside of the housing case 50 (the outside of the battery pack 11).

[0028] The microcontroller 31 is equipped with a CPU (Central Processing Unit). The functions provided by the microcontroller 31 can be provided by software recorded in a physical memory device and a computer that executes it, by software only, by hardware only, or by a combination thereof. For example, if the microcontroller 31 is provided by electronic circuits which are hardware, it can be provided by digital circuits including a large number of logic circuits, or by analog circuits. For example, the microcontroller 31 executes a program stored in a non-transitory tangible storage medium which serves as its own memory. The program may include, for example, a program for processing related to battery control. The method corresponding to the program is executed by executing a set of instructions that constitute the program. The memory is, for example, non-volatile memory. The program stored in the memory can be updated via a communication network such as the Internet, for example, OTA (Over The Air).

[0029] As an example of the main processing performed by the microcontroller 31, it acquires sensor information from various sensors 40 and performs various processes related to monitoring the battery pack 20, battery block 21, and battery cells 22 based on the sensor information. For example, the microcontroller 31 may transmit monitoring results (monitoring data) to the battery ECU 30. In this case, the microcontroller 31 may calculate the SOC and / or SOH based on the sensor information and transmit battery information including the calculated SOC and SOH to the battery ECU 30. The microcontroller 31 also controls relay switches, etc., to switch the energization and disconnection states between the battery pack 20 and the power control unit 12 and the motor 13 based on the monitoring results, etc. The microcontroller 31 may also transmit equalization signals to equalize the voltage of each battery cell 22. As shown in Figure 3, the microcontroller 31 is configured as a single device integrated with the sensors 40, but they may also be configured separately.

[0030] The battery ECU 30 is an electronic control unit. Based on monitoring results received from the microcontroller 31, the battery ECU 30 controls relay switches and other devices that switch the energization and disconnection states between the battery pack 20 and the power control unit 12 and the motor 13. The battery ECU 30 may also transmit equalization signals to equalize the voltage of each battery cell 22. The battery ECU 30 may also transmit monitoring results (monitoring data) to an external higher-level ECU, the vehicle ECU. In this case, the battery ECU 30 may transmit battery information, including SOC and SOH, to the vehicle ECU. As described above, the battery ECU 30 and the microcontroller 31 work together to monitor and manage the battery pack 20, battery block 21, and battery cells 22.

[0031] The housing case 50 is made of a conductor such as metal. The housing case 50 is formed in the shape of a metal box and is approximately a rectangular parallelepiped. It may also be made of a non-conductive material such as resin in part or in whole. As shown in Figure 3, the housing case 50 consists of a rectangular box-shaped case body 51 and a cover part 52 that covers the opening formed at the top of the case body 51.

[0032] The housing case 50 houses the battery pack 20, battery ECU 30, microcontroller 31, internal pressure sensor 44a, internal gas sensor 45a, internal humidity sensor 46a, and light receiving sensor 47 in its internal battery housing space. The housing case 50 is made of a light-shielding material and is configured to prevent light from passing through from the outside of the housing case 50. Furthermore, the housing case 50 has a sealed structure to ensure weather resistance. For this reason, the case body 51 and the cover portion 52 are sealed by a sealing member 53. The sealing member 53 is, for example, a rubber seal made of a resin such as rubber, but it may also be an adhesive or grease.

[0033] As mentioned above, the battery cell 22 is equipped with a cell explosion-proof valve 22a, and when the cell explosion-proof valve 22a opens, the gas accumulated inside the battery cell 22 is discharged. When gas is discharged from the battery cell 22, the atmospheric pressure inside the housing case 50 (hereinafter simply referred to as internal pressure) also rises. If the internal pressure exceeds a specified value, the battery pack 11 may rupture, so the housing case 50 is also equipped with an explosion-proof valve (safety valve). The explosion-proof valve of the housing case 50 is referred to as the pack explosion-proof valve 50a. The pack explosion-proof valve 50a is provided on the side wall of the housing case 50 or on the cover portion 52 (ceiling of the housing case 50). In this embodiment, as shown in Figure 3, it is provided approximately in the center of the side wall of the housing case 50. The pack explosion-proof valve 50a corresponds to the housing explosion-proof valve.

[0034] Furthermore, the explosion-proof pack valve 50a is designed to open by, for example, rupturing a pre-installed thin-walled section in a part of the housing case 50 in response to an increase in internal pressure, and does not have a structure that can be opened and closed by an electrical signal like a solenoid valve or an electric valve. In other words, once the explosion-proof pack valve 50a is opened, it is basically impossible to close it, and the housing case 50 needs to be replaced or repaired.

[0035] Incidentally, the battery pack 11 is required to be airtight. Therefore, if the pack explosion-proof valve 50a is opened, the sealing member 53 is damaged, or cracks are formed in the housing case 50, and the airtightness is lost, maintenance is required. However, conventionally, there was no way to determine whether or not the battery pack 11 was airtight, and checking the airtightness required time and effort.

[0036] Therefore, in this embodiment, the microcontroller 31 is equipped with a function to determine whether or not the battery pack 11 is airtight. This will be explained in detail below.

[0037] As shown in Figure 4, the microcontroller 31 has the function of a discrimination unit 32 that acquires detection values ​​from an internal sensor that detects physical quantities related to the internal state of the housing case 50 and determines the airtightness based on the acquired detection values. The microcontroller 31 also has the function of a notification unit 33 that notifies the user if the discrimination unit 32 determines that the case is not airtight. These functions are realized by the CPU of the microcontroller 31 executing a discrimination program stored in its memory.

[0038] In the first embodiment, the discrimination unit 32 acquires the internal pressure (internal atmospheric pressure value) of the housing case 50 detected by the internal pressure sensor 44a and determines the airtightness based on the acquired internal pressure. More specifically, the discrimination unit 32 acquires the internal pressure detected by the internal pressure sensor 44a and the external pressure (external atmospheric pressure value) detected by the external pressure sensor 44b, and determines the airtightness based on the pressure difference between the acquired internal pressure and the external pressure.

[0039] Furthermore, as a prerequisite for this determination, the internal pressure of the sealed storage case 50 is pre-set to be at least a first pressure difference threshold compared to the external pressure (the atmospheric pressure outside the storage case 50) under predetermined conditions. The predetermined conditions include, for example, temperature conditions, and are conditions that are met under typical natural conditions in the manufacturing region of the battery pack 11. The internal pressure of the sealed storage case 50 is an atmospheric pressure value that cannot be reached under natural conditions (or in the natural environment), and is set to an atmospheric pressure value that does not cause the pack explosion-proof valve 50a to rupture.

[0040] The discrimination process of the first embodiment will be explained based on the flowchart shown in Figure 5. The discrimination process is performed by the microcontroller 31 at predetermined intervals.

[0041] The discrimination unit 32 of the microcomputer 31 acquires (inputs) the internal pressure detected by the internal pressure sensor 44a from the internal pressure sensor 44a (step S101). Next, the discrimination unit 32 acquires (inputs) the external pressure detected by the external pressure sensor 44b from the external pressure sensor 44b (step S102). Then, the discrimination unit 32 compares the acquired internal pressure and external pressure, calculates the pressure difference (absolute value), and determines whether the pressure difference is less than or equal to the second pressure difference threshold value (step S103). The second pressure difference threshold value is set to a value smaller than the first pressure difference threshold value.

[0042] If the result of this determination is affirmative, the discrimination unit 32 determines that the airtightness has been lost. Accordingly, the notification unit 33 of the microcomputer 31 notifies the outside that the airtightness has been lost (step S104). Specifically, the notification unit 33 notifies (warns) an external upper ECU that the airtightness has been lost by means of wired communication or wireless communication. Further, the notification unit 33 may cause a notification device (such as a lamp or a speaker) to notify that there is no airtightness, or may notify an external server or the like via an external communication network. On the other hand, if the determination result in step S103 is negative, the discrimination unit 32 determines that the airtightness has not been lost (that is, it is normal), and ends the discrimination process. In the present embodiment, step S103 corresponds to a discrimination step, and step S104 corresponds to a notification step. Further, the microcomputer 31 corresponds to a discrimination device.

[0043] According to the first embodiment described above, the following effects are obtained.

[0044] The discrimination unit 32 discriminates the airtightness based on the internal pressure acquired from the internal pressure sensor 44a, and when it is discriminated that the airtightness has been lost, the notification unit 33 notifies an external device to that effect. Thereby, the airtightness can be discriminated with a relatively simple configuration, and it is possible to quickly know that the airtightness has been lost when the airtightness is lost.

[0045] The discrimination unit 32 acquires the external pressure and discriminates the airtightness based on the comparison between the external pressure and the internal pressure. Thereby, the airtightness can be discriminated more appropriately as compared with the case of determining only by the internal pressure.

[0046] The internal pressure of the storage case 50 when it is sealed is preset to be higher than the external pressure by a value equal to or greater than the first air pressure difference threshold value. The determination unit 32 compares the acquired internal pressure and external pressure to calculate the air pressure difference, and determines that the airtightness has been lost when the air pressure difference is equal to or less than the second air pressure difference threshold value that is smaller than the first air pressure difference threshold value. As a result, even if the external pressure fluctuates somewhat due to the external environment, the airtightness can be appropriately determined.

[0047] Further, the determination unit 32 refers to the air pressure (atmospheric pressure) as the physical quantity related to the internal state. And since setting the internal pressure to a predetermined value only requires filling with air, it is relatively easy compared to filling the inside of the storage case 50 with a specific gas or setting the humidity to a predetermined state. Therefore, the storage case 50 can be easily assembled.

[0048] (Modification of the First Embodiment) - In the above first embodiment, the internal pressure of the storage case 50 when it is sealed is preset to be higher than the external pressure by a value equal to or greater than the first air pressure difference threshold value under predetermined conditions. As a modification, the internal pressure of the storage case 50 when it is sealed may be preset to be lower than the external pressure by a value equal to or greater than the first air pressure difference threshold value under predetermined conditions.

[0049] (Second Embodiment) - A part of the configuration of the battery pack 11 of the first embodiment may be changed. Hereinafter, the battery pack 11 of the second embodiment in which a part of the battery pack 11 of the first embodiment is changed will be described. Note that the same components as those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and the drawings and description thereof are omitted.

[0050] The determination process by the determination unit 32 in the second embodiment will be described based on the flowchart shown in FIG. 6. The determination process is performed by the microcomputer 31 at a predetermined cycle. Note that in the determination process of the second embodiment, the processes of steps S201 to S204 are the same as the processes of steps S101 to S104 in the first embodiment, and thus the description thereof is omitted.

[0051] If the result of step S203 is negative, the discrimination unit 32 determines whether the internal pressure is outside a predetermined atmospheric pressure range (step S205). As a premise, the internal pressure when sealed is set to a value higher than or equal to the first atmospheric pressure difference threshold compared to the external pressure, so in step S205, the discrimination unit 32 determines whether the internal pressure is below a predetermined atmospheric pressure threshold. The atmospheric pressure threshold is set to a value that can occur in the external environment. That is, if the internal pressure of the storage case 50 is set to an atmospheric pressure value that cannot occur in natural conditions, but it is at an atmospheric pressure value that can occur in natural conditions, the discrimination unit 32 determines that airtightness has been lost.

[0052] If the result of step S205 is positive, the microcontroller 31 performs the process in step S204. On the other hand, if the result of step S205 is negative, the microcontroller 31 determines that the airtightness has not been lost (i.e., it is normal) and terminates the determination process.

[0053] According to the second embodiment described above, the following effects are achieved.

[0054] The discrimination unit 32 determines airtightness not only by the pressure difference but also by comparing the internal pressure with the pressure threshold. This allows for the determination of airtightness regardless of the external environment. Furthermore, it can detect abnormalities even if the external pressure sensor 44b malfunctions.

[0055] (Modification of the second embodiment) In the second embodiment described above, it is not necessary to determine airtightness based on the pressure difference between the internal pressure and the external pressure. In other words, the determination unit 32 may determine airtightness by comparing the internal pressure with the pressure threshold. In this case, the processing in steps S202 to S203 is omitted, and the process proceeds to steps S201 to S205. In this case, the external pressure sensor 44b may be omitted.

[0056] In the second embodiment described above, the internal pressure of the storage case 50 when sealed is set to be at least a first pressure difference threshold compared to the external pressure under predetermined conditions. As a variation of this, the internal pressure of the storage case 50 when sealed may be set to be at least a first pressure difference threshold compared to the external pressure under predetermined conditions. In this case, in step S205, the discrimination unit 32 will determine whether the internal pressure is at least a predetermined pressure threshold (a pressure value that can be taken in natural conditions).

[0057] (Third Embodiment) The configuration of the battery pack 11 of the first embodiment may be modified. The following describes the battery pack 11 of the third embodiment, which is a modified version of the battery pack 11 of the first embodiment. Components similar to those of the first embodiment are denoted by the same reference numerals as in the first embodiment, and the drawings and descriptions are omitted.

[0058] The discrimination process by the discrimination unit 32 of the third embodiment will be explained based on the flowchart shown in Figure 7. The discrimination process is performed by the microcontroller 31 at predetermined intervals. In the discrimination process of the third embodiment, the processes of steps S301 to S304 are the same as the processes of steps S101 to S104 of the first embodiment, so their explanation will be omitted.

[0059] If the determination result in step S303 is negative, the discrimination unit 32 compares the acquired internal pressure with the external pressure and determines whether the internal pressure is greater than or equal to the third pressure difference threshold compared to the external pressure (step S305). In other words, it determines whether the pressure difference obtained by subtracting the external pressure from the internal pressure is greater than or equal to the third pressure difference threshold. The third pressure difference threshold is set to a value greater than the first pressure difference threshold.

[0060] In other words, if the internal pressure is greater than the external pressure and is greater than the setting set when the battery is sealed, it is considered that the cell explosion-proof valve 22a of the battery cell 22 is opened, gas is released from the battery cell 22, and the internal pressure is rising. Therefore, if the internal pressure is greater than or equal to the third pressure difference threshold compared to the external pressure, it is possible to detect that some kind of abnormality has occurred in the battery pack 11.

[0061] Therefore, if the determination result in step S305 is positive, the discrimination unit 32 determines that an abnormality has occurred in the battery pack 11, and accordingly, the notification unit 33 of the microcontroller 31 notifies an external party of the abnormality of the battery pack 11 (step S306). The notification method and recipient are the same as in step S104, so the explanation is omitted.

[0062] On the other hand, if the determination result in step S305 is negative, the determination unit 32 determines that there is no abnormality in the battery pack 11 (i.e., it is normal) and terminates the determination process.

[0063] According to the microcontroller 31 of the third embodiment, it is possible to notify of an abnormality in the battery pack 11 while airtightness is not lost. This makes it possible to take action before the pack explosion-proof valve 50a opens, that is, before the housing case 50 is damaged. In this embodiment, the internal pressure sensor 44a and the external pressure sensor 44b function as a type of thermal runaway detection sensor that detects thermal runaway in the battery pack 11.

[0064] (Modification of the third embodiment) In the third embodiment described above, an abnormality in the battery pack 11 was determined based on the pressure difference. However, as an alternative, an abnormality in the battery pack 11 may be determined based on the rate of change of internal pressure. Specifically, the microcontroller 31 stores a history of internal pressure acquired at predetermined intervals and calculates the rate of change of internal pressure from this history. The microcontroller 31 may then determine that there is some kind of abnormality in the battery pack 11 if the rate of change of internal pressure is greater than or equal to a predetermined rate of increase (i.e., the rate at which the internal pressure rises is greater than or equal to a rate of increase threshold). In other words, when gas is discharged from the battery cell 22, the internal pressure rises sharply, so if the internal pressure changes at a rate of increase greater than or equal to a predetermined rate of increase, it may be determined that there is an abnormality in the battery pack 11. Note that this process may be performed instead of or together with step S305.

[0065] Normally, when the cell explosion-proof valve 22a is opened, the internal pressure rises rapidly before the pressure difference exceeds the third pressure difference threshold. Therefore, when detecting an abnormality based on the rate of change in internal pressure, it is possible to detect the abnormality more quickly compared to when detecting an abnormality based on the pressure difference.

[0066] In the third embodiment described above, the airtightness of the battery pack 11 was determined based on the pressure difference. However, as an alternative, the airtightness of the battery pack 11 may be determined based on the rate of change of internal pressure. Specifically, the microcontroller 31 calculates the rate of change of internal pressure as described above. The microcontroller 31 may then determine that the airtightness of the battery pack 11 has been lost if the rate of change of internal pressure is greater than or equal to a predetermined rate of decrease (i.e., if the rate at which the internal pressure decreases is greater than or equal to a rate of decrease threshold). In other words, if the internal pressure of the battery pack 11 increases and the pack explosion-proof valve 50a opens, the internal pressure drops sharply. Therefore, if the internal pressure changes at a rate greater than or equal to a predetermined rate of decrease, it may be determined that the airtightness of the battery pack 11 has been lost. This process may be performed instead of or together with step S303.

[0067] Normally, when the cell explosion-proof valve 22a is opened, the internal pressure drops rapidly before the pressure difference falls below the second pressure difference threshold. Therefore, when determining airtightness based on the rate of change of internal pressure, the loss of airtightness can be detected more quickly compared to when determining airtightness based on the pressure difference.

[0068] The third embodiment and its modifications may be combined with the second embodiment. In this case, for example, the processing from step S305 onwards may be performed after the processing in step S205.

[0069] (Fourth Embodiment) The battery pack 11 of the first embodiment may be modified in part. The following describes the battery pack 11 of the fourth embodiment, which is a modified version of the battery pack 11 of the first embodiment. Components similar to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their drawings and descriptions are omitted.

[0070] As shown in Figure 4, the various sensors 40 of the fourth embodiment always include an internal gas sensor 45a for measuring the concentration of a specific gas inside the housing case 50 and an external gas sensor 45b for measuring a specific gas outside the housing case 50. On the other hand, the fourth embodiment does not necessarily have to include any or all of the internal pressure sensor 44a, external pressure sensor 44b, internal humidity sensor 46a, external humidity sensor 46b, and light receiving sensor 47.

[0071] In the fourth embodiment, the discrimination unit 32 acquires the concentration of a specific gas inside the containment case 50 detected by the internal gas sensor 45a, and determines the airtightness based on the acquired concentration of the specific gas inside. More specifically, the discrimination unit 32 acquires the concentration of the specific gas inside the containment case 50 detected by the internal gas sensor 45a and the concentration of the specific gas outside the containment case 50 detected by the external gas sensor 45b, and determines the airtightness based on the difference between these concentrations. The specific gas is preferably a non-flammable gas and preferably a gas that can be discharged from the battery cell 22 when the cell explosion-proof valve 22a is opened. In this embodiment, CO2 is used as the specific gas.

[0072] Furthermore, as a prerequisite for this determination, a specific gas is filled inside a sealed containment case 50, and the concentration of the specific gas is pre-set to be higher than or equal to a first concentration difference threshold compared to the concentration of the specific gas contained in the outside air. The concentration of the specific gas filled into the containment case 50 at this time is set to a concentration that cannot be reached under natural conditions.

[0073] The discrimination process in the fourth embodiment will be explained based on the flowchart shown in Figure 8. The discrimination process is performed by the microcontroller 31 at predetermined intervals.

[0074] The discrimination unit 32 of the microcontroller 31 acquires (inputs) the concentration of the specific gas detected by the internal gas sensor 45a (step S401). Next, the discrimination unit 32 acquires (inputs) the concentration of the specific gas detected by the external gas sensor 45b (step S402). Then, the discrimination unit 32 compares the concentration of the specific gas inside with the concentration of the specific gas outside, calculates the concentration difference, and determines whether the concentration difference is less than or equal to a second concentration difference threshold (step S403). The second concentration difference threshold is set to a value smaller than the first concentration difference threshold.

[0075] If the determination result is positive, the discrimination unit 32 determines that airtightness has been lost, and accordingly, the notification unit 33 notifies the outside that airtightness has been lost (step S404). The processing in step S404 is the same as the processing in step S104 of the first embodiment. On the other hand, if the determination result in step S403 is negative, the discrimination unit 32 determines that airtightness has not been lost (i.e., it is normal), and terminates the discrimination process.

[0076] According to the fourth embodiment described above, the discrimination unit 32 determines the airtightness based on the concentration of a specific gas inside the containment case 50 detected by the internal gas sensor 45a, and if it is determined that airtightness has been lost, the notification unit 33 notifies the outside accordingly. This makes it possible to determine airtightness with a relatively simple configuration and to quickly know when airtightness has been lost.

[0077] The discrimination unit 32 acquires the concentration of a specific gas outside the containment case 50 and determines the airtightness based on the difference in concentration of the specific gas outside and inside. This allows for a more accurate determination of airtightness compared to judging solely on the concentration of the specific gas inside.

[0078] A specific gas is filled inside the sealed containment case 50 so that its concentration is higher than that of the specific gas in the outside air, by a value equal to or greater than a first concentration difference threshold. This allows for accurate determination of airtightness even if the concentration of the specific gas fluctuates slightly due to the external environment. Furthermore, the concentration of CO2 generally does not change as much as atmospheric pressure, which is affected by temperature, even if there are changes in the external environment. Therefore, loss of airtightness can be accurately determined regardless of the external conditions.

[0079] Since the specific gas is filled into the storage case 50 to a predetermined concentration when it is sealed, the internal pressure of the battery pack 11 when sealed can be reduced compared to the first embodiment. This provides ample time before the pack explosion-proof valve 50a opens.

[0080] (Modification of the fourth embodiment) The fourth embodiment may be implemented in combination with any of the first to third embodiments. That is, the discrimination process in the fourth embodiment may be implemented together with the discrimination process in any of the first to third embodiments. By detecting two or more physical quantities, namely atmospheric pressure and the concentration of a specific gas, and determining the loss of airtightness based on these detected values, the loss of airtightness can be determined more reliably.

[0081] The fourth embodiment described above may be implemented instead of the first to third embodiments. In other words, the discrimination process of the fourth embodiment may be implemented instead of the discrimination process of the first to third embodiments.

[0082] In the fourth embodiment described above, the concentration of the specific gas inside the sealed containment case 50 was preset to be higher than or equal to a first concentration difference threshold compared to the concentration of the specific gas outside. As a variation of this, the concentration of the specific gas inside the sealed containment case 50 may be preset to be lower than or equal to a first concentration difference threshold compared to the concentration of the specific gas outside.

[0083] (Fifth Embodiment) The battery pack 11 of the fourth embodiment described above may be modified in part. The battery pack 11 of the fifth embodiment, which is modified in part in the battery pack 11 of the fourth embodiment described below, will be explained. Note that the same configuration as in the fourth embodiment will be omitted from the drawings and descriptions in principle.

[0084] The discrimination process by the discrimination unit 32 of the fifth embodiment will be explained based on the flowchart shown in Figure 9. The discrimination process is performed by the microcontroller 31 at predetermined intervals. In the discrimination process of the fifth embodiment, the processes of steps S501 to S504 are the same as the processes of steps S401 to S404 of the fourth embodiment, so their explanation will be omitted.

[0085] If the result of step S503 is negative, the discrimination unit 32 determines whether the concentration of the specific gas inside the containment case 50 is outside a predetermined concentration range (step S505). As a premise, the concentration of the specific gas inside when sealed is set to be higher than or equal to the first concentration difference threshold compared to the outside, so in step S505, the discrimination unit 32 determines whether the concentration of the specific gas inside the containment case 50 is below a predetermined concentration threshold. It is desirable that the concentration threshold be a value lower than the concentration of the specific gas in the initial state (the state immediately after filling with the specific gas) (a predetermined concentration), and that it is a value that allows for the determination that the specific gas has leaked.

[0086] If the result of step S505 is positive, the microcontroller 31 performs the process in step S504. On the other hand, if the result of step S505 is negative, the microcontroller 31 determines that airtightness has not been lost (i.e., it is normal) and terminates the determination process.

[0087] According to the fifth embodiment described above, the discrimination unit 32 determines airtightness not only by the concentration difference but also by comparing the concentration of a specific gas inside the containment case 50 with a concentration threshold. This makes it possible to determine airtightness regardless of the external environment. Furthermore, it can also determine airtightness even if an abnormality occurs in the external gas sensor 45b.

[0088] (Modification of the Fifth Embodiment) In the fifth embodiment described above, it is not necessary to determine airtightness based on the concentration difference between the inside and outside. In other words, the determination unit 32 may determine airtightness simply by comparing the concentration of a specific gas inside the containment case 50 with a concentration threshold. In this case, the processing in steps S502 to S503 is omitted, and the process proceeds from step S501 to step S505. The external gas sensor 45b may also be omitted.

[0089] The fifth embodiment described above may be implemented in combination with any of the first to fourth embodiments described above. That is, the discrimination process in the fifth embodiment may be implemented together with the discrimination process in any of the first to fourth embodiments.

[0090] The fifth embodiment described above may be implemented instead of the first to fourth embodiments. In other words, the fifth embodiment may be implemented instead of the discrimination process of the first to fourth embodiments.

[0091] In the fifth embodiment described above, the concentration of the specific gas inside the sealed containment case 50 is set to be higher than or equal to a first concentration difference threshold compared to the concentration of the specific gas outside. As a variation of this, the concentration of the specific gas inside the sealed containment case 50 may be set to be lower than or equal to a first concentration difference threshold compared to the concentration of the specific gas outside. In this case, in step S505, the discrimination unit 32 will determine whether or not the concentration of the specific gas inside is higher than or equal to a predetermined concentration threshold (a concentration that can occur under natural conditions).

[0092] (Sixth Embodiment) The configuration of the battery pack 11 of the fourth embodiment may be modified. The following describes the battery pack 11 of the sixth embodiment, which is a modified version of the battery pack 11 of the fourth embodiment. Components similar to those of the fourth embodiment are denoted by the same reference numerals as in the fourth embodiment, and their drawings and descriptions are omitted.

[0093] The discrimination process by the discrimination unit 32 of the sixth embodiment will be explained based on the flowchart shown in Figure 10. The discrimination process is performed by the microcontroller 31 at predetermined intervals. In the discrimination process of the sixth embodiment, the processes of steps S601 to S604 are the same as the processes of steps S401 to S404 of the fourth embodiment, so their explanation will be omitted.

[0094] The discrimination unit 32 compares the concentration of the specific gas inside with the concentration of the specific gas outside and determines whether the concentration of the specific gas inside is greater than or equal to a third concentration difference threshold compared to the concentration of the specific gas outside (step S605). In other words, it determines whether the concentration difference obtained by subtracting the concentration of the specific gas outside from the concentration of the specific gas inside is greater than or equal to a third concentration difference threshold. The third concentration difference threshold is set to a value greater than the first concentration difference threshold.

[0095] In other words, when the cell explosion-proof valve 22a of the battery cell 22 is opened and the airtightness of the battery pack 11 is ensured, if a specific gas is discharged from the battery cell 22, the concentration of the specific gas inside the housing case 50 may temporarily exceed the concentration set when it was sealed. Therefore, if the concentration of the specific gas inside is greater than or equal to the third concentration difference threshold compared to the concentration of the specific gas outside, it is possible to detect that some kind of abnormality has occurred in the battery pack 11.

[0096] Therefore, if the determination result in step S605 is positive, the discrimination unit 32 determines that an abnormality has occurred in the battery pack 11, and accordingly, the notification unit 33 of the microcontroller 31 notifies the outside of the abnormality of the battery pack 11 (step S606). The notification method and recipient are the same as in step S104, so the explanation is omitted. On the other hand, if the determination result in step S605 is negative, the discrimination unit 32 determines that there is no abnormality in the battery pack 11 (i.e., it is normal), and terminates the discrimination process.

[0097] According to the microcontroller 31 of the sixth embodiment, it is possible to notify of an abnormality in the battery pack 11 while airtightness is not lost. This makes it possible to take action before the pack explosion-proof valve 50a opens, that is, before the housing case 50 is damaged. In this embodiment, the internal gas sensor 45a and the external gas sensor 45b function as a type of thermal runaway detection sensor that detects thermal runaway in the battery pack 11.

[0098] (Modification of the sixth embodiment) In the sixth embodiment described above, an abnormality in the battery pack 11 was determined based on the concentration difference of a specific gas. However, as a modification of this, an abnormality in the battery pack 11 may be determined based on the rate of change of the concentration of the specific gas inside. Specifically, the microcontroller 31 stores a history of the concentration of the specific gas inside acquired at predetermined intervals and calculates the rate of change of the concentration of the specific gas inside from this history. The microcontroller 31 may then determine that there is some kind of abnormality in the battery pack 11 if the rate of change of the concentration of the specific gas inside is greater than or equal to a predetermined rate of increase (i.e., the rate of change of the concentration of the specific gas inside is greater than or equal to a rate of increase threshold). In other words, when gas is discharged from the battery cell 22, the concentration of the specific gas inside rises sharply, so if the concentration of the specific gas inside changes at a rate of increase greater than or equal to a predetermined rate of increase, it may be determined that there is an abnormality in the battery pack 11. Note that this process may be performed instead of step S605, or together with step S605.

[0099] Normally, when the cell explosion-proof valve 22a is opened, the concentration of the specific gas inside rises rapidly before the concentration difference exceeds the third concentration difference threshold. Therefore, when detecting an abnormality based on the rate of change in the concentration of the specific gas inside, it is possible to detect the abnormality more quickly compared to when detecting an abnormality based on the concentration difference.

[0100] ・In the sixth embodiment described above, the airtightness of the battery pack 11 was determined based on the concentration difference, but as a modification, the airtightness of the battery pack 11 may be determined based on the rate of change of the concentration of a specific gas inside. Specifically, the microcomputer 31 calculates the rate of change of the concentration of the specific gas inside, as described above. The microcomputer 31 may then determine that the battery pack 11 has lost its airtightness if the rate of change of the concentration of the specific gas inside is greater than or equal to a predetermined rate of decrease (i.e., if the rate of change of the concentration of the specific gas inside is greater than or equal to a rate of decrease threshold). In other words, as the internal pressure of the battery pack 11 increases, the concentration of the specific gas inside also increases, and then the pack explosion-proof valve 50a, etc., opens. After opening, the internal pressure drops sharply and the concentration of the specific gas inside also drops sharply, so if the concentration of the specific gas inside changes at a rate of decrease greater than or equal to a predetermined rate of decrease, it may be determined that the battery pack 11 has lost its airtightness. This process may be performed instead of step S603, or together with step S603.

[0101] Normally, when the cell explosion-proof valve 22a is opened, the concentration of the specific gas inside drops sharply before the concentration difference falls below the second concentration difference threshold. Therefore, when determining airtightness based on the rate of change in the concentration of the specific gas inside, the loss of airtightness can be detected more quickly compared to when determining airtightness based on the concentration difference.

[0102] The sixth embodiment and its modified form may be combined with the fifth embodiment. In this case, for example, the processing from step S605 onwards may be performed after the processing in step S505. The sixth embodiment and its modified form may be combined with any of the first to fourth embodiments.

[0103] (Seventh Embodiment) The battery pack 11 of the first embodiment may be modified in part. The following describes the seventh embodiment of the battery pack 11, which is a modified version of the battery pack 11 of the first embodiment. Components similar to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their drawings and descriptions are omitted.

[0104] As shown in Figure 4, the various sensors 40 of the seventh embodiment always include an internal humidity sensor 46a for measuring humidity inside the housing case 50 and an external humidity sensor 46b for measuring humidity outside the housing case 50. On the other hand, the seventh embodiment does not necessarily have to include any or all of the internal pressure sensor 44a, external pressure sensor 44b, internal gas sensor 45a, external gas sensor 45b, and light receiving sensor 47.

[0105] In the seventh embodiment, the discrimination unit 32 acquires the humidity inside the housing case 50 detected by the internal humidity sensor 46a and determines the airtightness based on the acquired internal humidity. More specifically, the discrimination unit 32 acquires the humidity inside the housing case 50 detected by the internal humidity sensor 46a and the humidity outside the housing case 50 detected by the external humidity sensor 46b, and determines the airtightness based on the difference between these humidity levels.

[0106] Furthermore, as a prerequisite for this determination, the humidity inside the sealed storage case 50 is pre-adjusted to be different from the humidity outside. In this embodiment, the humidity inside the sealed storage case 50 is pre-adjusted to be at least one humidity difference threshold lower than the lowest humidity that can occur outside.

[0107] The discrimination process in the seventh embodiment will be explained based on the flowchart shown in Figure 11. The discrimination process is performed by the microcontroller 31 at predetermined intervals.

[0108] The discrimination unit 32 of the microcontroller 31 acquires (inputs) the internal humidity detected by the internal humidity sensor 46a from the internal humidity sensor 46a (step S701). Next, the discrimination unit 32 acquires (inputs) the external humidity detected by the external humidity sensor 46b from the external humidity sensor 46b (step S702). Then, the discrimination unit 32 compares the acquired internal humidity with the external humidity to calculate the humidity difference and determines whether the humidity difference is less than or equal to a second humidity difference threshold (step S703). The second humidity difference threshold is set to a value smaller than the first humidity difference threshold.

[0109] If the determination result is positive, the discrimination unit 32 determines that airtightness has been lost, and accordingly, the notification unit 33 notifies the outside that airtightness has been lost (step S704). The processing in step S704 is the same as the processing in step S104 of the first embodiment. On the other hand, if the determination result in step S703 is negative, the discrimination unit 32 determines that airtightness has not been lost (i.e., it is normal), and terminates the discrimination process.

[0110] According to the seventh embodiment described above, the discrimination unit 32 determines the airtightness based on the internal humidity obtained from the internal humidity sensor 46a, and if it is determined that the airtightness has been lost, the notification unit 33 notifies the outside accordingly. This makes it possible to determine the airtightness with a relatively simple configuration and to quickly know when the airtightness has been lost.

[0111] The discrimination unit 32 acquires the humidity outside the storage case 50 and determines the airtightness based on the difference in humidity between the outside and inside. This allows for a more accurate determination of airtightness compared to judging solely on the humidity inside.

[0112] The humidity inside the sealed storage case 50 is pre-adjusted to be at least one level lower than the lowest possible humidity outside, and the discrimination unit 32 determines that there is no airtightness when the humidity difference falls below a second humidity difference threshold, which is smaller than the first humidity difference threshold. This allows for appropriate determination of airtightness even if the humidity fluctuates somewhat due to the external environment.

[0113] Since the humidity can be set when the housing case 50 is sealed, the internal pressure of the battery pack 11 when sealed can be reduced compared to the first embodiment. This provides ample time before the pack explosion-proof valve 50a opens.

[0114] (Modification of the 7th Embodiment) The 7th embodiment may be implemented in combination with any of the 1st to 6th embodiments. That is, the discrimination process in the 7th embodiment may be implemented together with the discrimination process in any of the 1st to 6th embodiments. Furthermore, by detecting two or more physical quantities, namely atmospheric pressure and the concentration of a specific gas, atmospheric pressure and humidity, the concentration of a specific gas and humidity, or atmospheric pressure, the concentration of a specific gas and humidity, and determining the loss of airtightness based on these detected values, the loss of airtightness can be determined more reliably.

[0115] The seventh embodiment described above may be implemented instead of the first to sixth embodiments. In other words, the discrimination process of the seventh embodiment may be implemented instead of the discrimination process of the first to sixth embodiments.

[0116] In the seventh embodiment described above, the humidity inside the sealed storage case 50 was pre-set to be at least one humidity difference threshold lower than the lowest humidity that could occur outside. As a variation of this, the humidity inside may be pre-set to be at least one humidity difference threshold higher than the highest humidity that could occur outside.

[0117] (Eighth Embodiment) The battery pack 11 of the seventh embodiment may be modified in part. The following describes the battery pack 11 of the eighth embodiment, which is a modified version of the battery pack 11 of the seventh embodiment. Note that the same configuration as in the seventh embodiment will be omitted from the drawings and descriptions.

[0118] The discrimination process by the discrimination unit 32 of the eighth embodiment will be explained based on the flowchart shown in Figure 12. The discrimination process is performed by the microcontroller 31 at predetermined intervals. In the discrimination process of the eighth embodiment, the processes of steps S801 to S804 are the same as the processes of steps S701 to S704 of the seventh embodiment, so their explanation will be omitted.

[0119] If the result of step S803 is negative, the discrimination unit 32 determines whether the humidity inside the storage case 50 is outside a predetermined humidity range (step S805). As a premise, the humidity inside when sealed is set to be lower than or equal to the humidity outside by a first humidity difference threshold, so in step S805, the discrimination unit 32 determines whether the humidity inside the storage case 50 is above or equal to a predetermined humidity threshold. It is desirable that the humidity threshold is a value higher than the humidity in the initial state (pre-set humidity) and is high enough to determine that air is flowing in from the outside.

[0120] If the result of step S805 is positive, the microcontroller 31 performs the process in step S804. On the other hand, if the result of step S805 is negative, the microcontroller 31 determines that the airtightness has not been lost (i.e., it is normal) and terminates the determination process.

[0121] According to the sixth embodiment described above, the discrimination unit 32 determines airtightness not only by comparing the humidity difference but also by comparing the humidity inside the housing case 50 with the humidity threshold. This makes it possible to determine airtightness regardless of the external environment. Furthermore, it can also determine airtightness even if an abnormality occurs in the external humidity sensor 46b.

[0122] (Modification of the 8th embodiment) In the 8th embodiment described above, it is not necessary to determine airtightness based on the difference in humidity between the inside and outside. In other words, the determination unit 32 may determine airtightness simply by comparing the humidity inside the housing case 50 with the humidity threshold. In this case, the processing in steps S802 to S803 will be omitted. The external humidity sensor 46b may also be omitted.

[0123] The eighth embodiment described above may be implemented in combination with any of the first to seventh embodiments described above. That is, the discrimination process in the eighth embodiment may be implemented together with the discrimination process in any of the first to seventh embodiments.

[0124] The eighth embodiment described above may be implemented instead of the first to seventh embodiments. In other words, the eighth embodiment may be implemented instead of the discrimination process of the first to seventh embodiments.

[0125] In the seventh or eighth embodiment described above, the discrimination unit 32 may calculate the rate of change of humidity inside and determine that an abnormality has occurred in the battery pack 11 if the rate of change of humidity inside is greater than or equal to a rate threshold (i.e., if the humidity rises sharply).

[0126] (Ninth Embodiment) The battery pack 11 of the first embodiment may be modified in part. The following describes the battery pack 11 of the ninth embodiment, which is a modified version of the battery pack 11 of the first embodiment. Components similar to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their drawings and descriptions are omitted.

[0127] As shown in Figure 4, the various sensors 40 of the ninth embodiment always include a light receiving sensor 47 that measures the amount of light inside the housing case 50. On the other hand, the ninth embodiment does not need to include any or all of the internal pressure sensor 44a, external pressure sensor 44b, internal gas sensor 45a, external gas sensor 45b, internal humidity sensor 46a, and external humidity sensor 46b.

[0128] The discrimination unit 32 of the ninth embodiment acquires the amount of light detected by the light receiving sensor 47 and determines the airtightness based on the acquired amount of light. Furthermore, as a prerequisite for this discrimination, the storage case 50 is made of a material that does not transmit light from the outside, and the storage case 50 is sealed so as not to allow light from the outside to pass through.

[0129] The discrimination process in the ninth embodiment will be explained based on the flowchart shown in Figure 13. The discrimination process is performed by the microcontroller 31 at predetermined intervals.

[0130] The discrimination unit 32 of the microcontroller 31 acquires (inputs) the amount of light detected (measured) by the light receiving sensor 47 from the light receiving sensor 47 (step S901). Next, the discrimination unit 32 determines whether the acquired amount of light is equal to or greater than a first light amount threshold (step S902). If this determination result is positive, the discrimination unit 32 determines that airtightness has been lost, and accordingly, the notification unit 33 notifies the outside that airtightness has been lost (step S903). The processing in step S903 is the same as the processing in step S104 of the first embodiment. On the other hand, if the determination result in step S902 is negative, the discrimination unit 32 determines that airtightness has not been lost (i.e., it is normal), and terminates the discrimination process.

[0131] According to the ninth embodiment described above, the discrimination unit 32 determines the airtightness based on the amount of light inside the housing case 50 obtained from the light receiving sensor 47, and if it is determined that the airtightness has been lost, the notification unit 33 notifies the outside accordingly. This makes it possible to determine the airtightness with a relatively simple configuration and to quickly know when the airtightness has been lost.

[0132] (Modification of the 9th Embodiment) The 9th embodiment may be implemented in combination with any of the 1st to 8th embodiments. That is, the discrimination process in the 9th embodiment may be implemented together with the discrimination process in any of the 1st to 8th embodiments. Furthermore, by determining the loss of airtightness based on the detected values ​​of two or more physical quantities from atmospheric pressure, the concentration of a specific gas, humidity, and light intensity, the loss of airtightness can be determined more reliably.

[0133] The ninth embodiment described above may be implemented instead of the first to eighth embodiments. In other words, the discrimination process of the ninth embodiment may be implemented instead of the discrimination process of the first to eighth embodiments.

[0134] - The light receiving sensor 47 in the ninth embodiment described above may be provided inside the housing case 50 in a position facing the pack explosion-proof valve 50a, as shown in Figure 14. This makes it easier to detect that airtightness has been lost when the pack explosion-proof valve 50a opens.

[0135] - The light receiving sensor 47 of the ninth embodiment described above may be provided inside the housing case 50, as shown in Figure 14, in a position facing the sealing member 53 between the case body 51 and the cover portion 52. This makes it easier to detect that airtightness has been lost when the cover portion 52 is open.

[0136] (Tenth Embodiment) The battery pack 11 of the first embodiment may be modified in part. The following describes the battery pack 11 of the tenth embodiment, which is a modified version of the battery pack 11 of the first embodiment. Components similar to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their drawings and descriptions are omitted.

[0137] As shown in Figure 15, the various sensors 40 of the tenth embodiment always include a light-receiving sensor 47 that measures the amount of light inside the housing case 50. On the other hand, in the tenth embodiment, it is not necessary to include any or all of the internal pressure sensor 44a, external pressure sensor 44b, internal gas sensor 45a, external gas sensor 45b, internal humidity sensor 46a, and external humidity sensor 46b. Also, as shown in Figure 15, the battery pack 11 includes a light-emitting element 48. As shown in Figure 16, the light-emitting element 48 is arranged inside the housing case 50 so as to face the light-receiving sensor 47. In the tenth embodiment, the light-receiving sensor 47 and the light-emitting element 48 are arranged on the upper side of the housing case 50, more specifically, above the upper surface of the battery cell 22.

[0138] The discrimination unit 32 of the tenth embodiment, similar to the ninth embodiment, determines airtightness based on the amount of light detected by the light receiving sensor 47. In addition, the discrimination unit 32 of the tenth embodiment is configured to determine an abnormality in the battery pack 11 based on whether or not it can emit light from the light-emitting element 48 and measure an amount of light equal to or greater than a predetermined second light-intensity threshold when the airtightness of the battery pack 11 is ensured, that is, when the amount of light is less than a first light-intensity threshold. The second light-intensity threshold may be the same value as the first light-intensity threshold, or it may be different.

[0139] To explain in more detail, if smoke or other substances are generated inside the battery pack 11 due to thermal runaway or fire, the light from the light-emitting element 48 to the light-receiving sensor 47 will be blocked. Therefore, the discrimination unit 32 determines whether the battery pack 11 is abnormal by emitting light from the light-emitting element 48 and determining whether the light-receiving sensor 47 can properly receive light, provided that the airtightness of the battery pack 11 is ensured.

[0140] The discrimination process of the tenth embodiment will be explained based on the flowchart shown in Figure 17. The discrimination process is performed by the microcontroller 31 at predetermined intervals. Steps S1001 to S1003 in the tenth embodiment are the same as steps S901 to S903 in the ninth embodiment, so their explanation will be omitted.

[0141] If the determination result in step S1002 is negative, that is, if the acquired light intensity is less than the first light intensity threshold and airtightness is ensured, the determination unit 32 causes the light-emitting element 48 to emit light (step S1004). In this state, the determination unit 32 acquires (inputs) the light intensity measured by the light-receiving sensor 47 from the light-receiving sensor 47 (step S1005). Next, the determination unit 32 determines whether the acquired light intensity is equal to or greater than the second light intensity threshold (step S1006). In the normal state, the second light intensity threshold is set to a value corresponding to the light intensity measured by the light-receiving sensor 47 when the light-emitting element 48 emits light.

[0142] If this determination result is negative, that is, if the light from the light-emitting element 48 is blocked by smoke or the like and the light-receiving sensor 47 cannot detect a sufficient amount of light, the discrimination unit 32 determines that there is an abnormality in the battery pack 11, and accordingly, the notification unit 33 of the microcontroller 31 notifies an external party of the abnormality in the battery pack 11 (step S1007). The notification method and recipient are the same as in step S104, so the explanation is omitted.

[0143] On the other hand, if the determination result in step S1006 is positive, that is, if the light from the light-emitting element 48 is not blocked and the opposing light-receiving sensor 47 is able to detect a sufficient amount of light, the discrimination unit 32 determines that it is normal and terminates the discrimination process.

[0144] According to the microcontroller 31 of the tenth embodiment, by emitting light from the light-emitting element 48 and determining whether the light-receiving sensor 47 can properly receive light, it is possible to determine whether smoke is being generated inside. In other words, it is possible to quickly detect and notify of an abnormality in the battery pack 11. In this embodiment, the light-emitting element 48 and the light-receiving sensor 47 function as a type of thermal runaway detection sensor that detects thermal runaway in the battery pack 11.

[0145] (Modification of the 10th embodiment) The 10th embodiment may be implemented in combination with any of the 1st to 9th embodiments.

[0146] The 10th embodiment may be implemented instead of the 1st to 8th embodiments. In other words, the discrimination process of the 10th embodiment may be implemented instead of the discrimination process of the 1st to 8th embodiments.

[0147] In the tenth embodiment described above, if the determination result of step S1002 was negative, that is, if it was determined that airtightness was ensured, the processing from step S1004 onwards was performed to detect an abnormality in the battery pack 11. As a modification of this, regardless of the determination result of step S1002, that is, regardless of whether airtightness is ensured or not, the processing from step S1004 onwards may be performed to detect an abnormality in the battery pack 11. In this case, the processing from steps S1001 to S1003 may not be performed.

[0148] (Modifications of the above embodiments) In each of the above embodiments, the execution cycle of the discrimination process (discrimination cycle) may be changed arbitrarily. Also, if information indicating that an impact has occurred is obtained from the impact detection sensor that detects impacts to the vehicle or battery pack 11, the discrimination unit 32 may shorten the execution cycle compared to the normal execution cycle. Similarly, if an acceleration of a predetermined value or higher is input from the acceleration sensor that detects the acceleration of the vehicle, the discrimination unit 32 may shorten the execution cycle compared to the normal execution cycle. For example, as shown in Figure 18, the discrimination unit 32 determines whether or not it has obtained information indicating that an impact has occurred from the impact detection sensor (step S1101). If this determination result is positive, the discrimination unit 32 shortens the discrimination cycle (step S1102). If the determination result of step S1101 is negative, the discrimination unit 32 determines whether or not an acceleration of a predetermined value or higher has been input from the acceleration sensor (step S1103). If this determination result is positive, the discrimination unit 32 performs the process of step S1102. On the other hand, if this determination result is negative, the discrimination unit 32 terminates the process. Note that either step S1101 or step S1103 may be performed.

[0149] In each of the above embodiments, the discrimination process may be performed at any time. For example, the discrimination process may be performed when the ignition switch is turned on or when the vehicle starts moving (for example, when the shift lever is in the "D" position).

[0150] In each of the above embodiments, the microcontroller 31 may be incorporated into the battery ECU 30, as shown in Figures 19 and 20. Alternatively, for example, the microcontroller of the battery ECU 30 may be equipped with the functions of the microcontroller 31 (such as the discrimination unit 32 and the notification unit 33).

[0151] In each of the above embodiments, the battery ECU 30, the microcontroller 31, and the various sensors 40 may be integrated and configured as a single device.

[0152] In each of the above embodiments, the internal pressure sensor 44a and the external pressure sensor 44b may be integrated. For example, as shown in Figure 21, a pressure sensor 145, which integrates the internal pressure sensor 44a and the external pressure sensor 44b, may be inserted and fixed so as to penetrate the side wall of the housing case 50. The internal and external pressures may then be detected by this pressure sensor 145. Compared to the case where they are separate, it only requires one component, thus reducing the number of parts. The pressure sensor 145 is, for example, a tank internal pressure sensor manufactured by Denso Corporation.

[0153] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0154] The following is an addition regarding the technical ideas that can be derived from each of the above embodiments and modifications. [Configuration 1] A discrimination device (30) for determining the airtightness of a battery pack (11) having a housing (50) for housing batteries (20, 21, 22), comprising: a discrimination unit (32) that acquires detected values ​​from one or more internal sensors (44a, 45a, 46a, 47) that detect physical quantities related to the internal state of the housing, and determines the airtightness based on the acquired detected values; and a notification unit (33) that notifies the discrimination unit if it determines that the airtightness is not present. [Configuration 2] The discrimination device according to Configuration 1, wherein the discrimination unit acquires detected values ​​from one or more external sensors (44b, 45b, 46b) that detect physical quantities related to the external state of the housing, and determines the airtightness based on a comparison between the detected values ​​of the internal sensors and the detected values ​​of the external sensors. [Configuration 3] The internal sensor and the external sensor include a pressure sensor for measuring atmospheric pressure, and the internal pressure of the housing is set to be different from the external pressure when the housing is sealed, and the discrimination unit determines that the airtightness has been lost when the pressure difference between the atmospheric pressure detected by the external sensor and the atmospheric pressure detected by the internal sensor falls below a pressure difference threshold, as described in Configuration 1 or 2. [Configuration 4] The internal sensor and the external sensor include a gas sensor for detecting the concentration of a specific gas, and the internal pressure of the housing is set to be different from the external pressure of the housing when the housing is sealed, and the discrimination unit determines that the airtightness has been lost when the concentration difference between the concentration of the specific gas detected by the external sensor and the concentration of the specific gas detected by the internal sensor falls below a concentration difference threshold, as described in Configuration 1 to 3.[Configuration 5] The internal sensor and the external sensor include a humidity sensor for detecting humidity, and the humidity inside the housing is set in advance so that it is different from the humidity outside when the housing is sealed, and the discrimination unit determines that the airtightness has been lost when the humidity difference between the humidity detected by the external sensor and the humidity detected by the internal sensor falls below a humidity difference threshold, as described in any configuration 1 to 4. [Configuration 6] The physical quantities related to the internal state of the housing are set in advance when the housing is sealed, and the discrimination unit determines the airtightness based on whether the value detected by the internal sensor is within a predetermined range, as described in any configuration 1 to 5. [Configuration 7] The internal sensor includes a pressure sensor for measuring atmospheric pressure, and the atmospheric pressure inside the housing is set in advance so that it is within a predetermined range when the housing is sealed, and the discrimination unit determines that the airtightness has been lost when the atmospheric pressure detected by the internal sensor falls outside a predetermined atmospheric pressure range, as described in any configuration 1 to 6. [Configuration 8] The internal sensor includes a gas sensor for detecting the concentration of a specific gas, the specific gas is filled inside the housing so that when the housing is sealed, the concentration of the specific gas inside the housing is a predetermined concentration, and the discrimination unit determines that the airtightness has been lost if the concentration of the specific gas detected by the internal sensor falls outside a predetermined concentration range, as described in any configuration 1 to 7. [Configuration 9] The internal sensor includes a humidity sensor for detecting humidity, the humidity inside the housing is set in advance so that when the housing is sealed, the humidity inside the housing is a predetermined humidity, and the discrimination unit determines that the airtightness has been lost if the humidity detected by the internal sensor falls outside a predetermined humidity range, as described in any configuration 1 to 8.[Configuration 10] The internal sensor includes a light receiving sensor for measuring the amount of light, the housing is made of a material that does not transmit light from the outside, and the housing is sealed so as not to allow light from the outside to pass through, and the discrimination unit determines that the airtightness has been lost when the amount of light measured by the light receiving sensor exceeds a predetermined light amount threshold, as described in any of Configurations 1 to 9. [Configuration 11] The housing is provided with an explosion-proof valve (50a) for the housing that opens when the air pressure inside the housing exceeds a predetermined value, and the light receiving sensor is arranged to face the explosion-proof valve for the housing, as described in Configuration 10. [Configuration 12] A discrimination device according to Configuration 10 or 11, having a light-emitting element (48) positioned opposite the light-receiving sensor, wherein the discrimination unit emits light from the light-emitting element when the amount of light measured by the light-receiving sensor is less than a light intensity threshold, and determines that it is normal if the amount of light measured by the light-receiving sensor is equal to or greater than the light intensity threshold, while determining that it is abnormal if the amount of light measured by the light-receiving sensor is less than the light intensity threshold. [Configuration 13] A discrimination device according to any one of Configurations 1 to 12, wherein the discrimination unit acquires a physical quantity related to the internal state at predetermined timings, calculates the rate of change of the physical quantity from the acquired physical quantity related to the internal state, and determines whether or not an abnormality has occurred inside the housing based on whether or not the rate of change of the physical quantity is equal to or greater than a predetermined rate threshold. [Configuration 14] The discrimination unit is configured to repeatedly perform the acquisition of the detected value and the determination of airtightness at a predetermined discrimination cycle, and the discrimination unit shortens the discrimination cycle compared to normal when an impact is detected by the impact detection sensor or when an acceleration of a predetermined value or more is detected by the acceleration sensor, as described in any of Configurations 1 to 13. [Configuration 15] The discrimination device is configured to be configured in any of Configurations 1 to 14, wherein the internal sensor is a thermal runaway detection sensor for detecting thermal runaway inside the battery pack.[Configuration 16] A determination program to be performed by a determination device (30) for determining the airtightness of a battery pack (11) having a housing (50) for housing batteries (20, 21, 22), comprising: a determination step of obtaining detection values ​​from one or more internal sensors that detect physical quantities related to the internal state of the housing, and determining the airtightness based on the obtained detection values; and a notification step of notifying the device if it is determined in the determination step that the airtightness is not present.

[0155] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A determination device (31) for determining the airtightness of a battery pack (11) having a housing (50) for housing batteries (20, 21, 22), comprising: a determination unit (32) that acquires detected values ​​from one or more internal sensors (44a, 45a, 46a, 47) that detect physical quantities related to the internal state of the housing, and determines the airtightness based on the acquired detected values; and a notification unit (33) that notifies the determination unit if it determines that the airtightness is not present.

2. The discrimination device according to claim 1, wherein the discrimination unit obtains detected values ​​from one or more external sensors (44b, 45b, 46b) that detect physical quantities related to the external state of the housing, and determines the airtightness based on a comparison between the detected values ​​of the internal sensors and the detected values ​​of the external sensors.

3. The internal sensor and the external sensor include a pressure sensor for measuring atmospheric pressure, and the internal pressure of the housing is set in advance to be different from the external pressure when the housing is sealed, and the determination unit determines that the airtightness has been lost when the pressure difference between the atmospheric pressure detected by the external sensor and the atmospheric pressure detected by the internal sensor falls below a pressure difference threshold.

4. The internal sensor and the external sensor include a gas sensor for detecting the concentration of a specific gas, and the internal sensor and the external sensor are pre-set so that when the housing is sealed, the concentration of the specific gas inside the housing is different from the concentration of the specific gas outside, and the discrimination unit determines that the airtightness has been lost when the concentration difference between the concentration of the specific gas detected by the external sensor and the concentration of the specific gas detected by the internal sensor falls below a threshold for the concentration difference.

5. The discrimination device according to claim 2, wherein the internal sensor and the external sensor include a humidity sensor for detecting humidity, and the humidity inside the housing is set in advance to be different from the humidity outside when the housing is sealed, and the discrimination unit determines that the airtightness has been lost when the humidity difference between the humidity detected by the external sensor and the humidity detected by the internal sensor falls below a humidity difference threshold.

6. The determination device according to any one of claims 1 to 5, wherein the physical quantities relating to the internal state of the housing when the housing is sealed are set in advance, and the determination unit determines the airtightness based on whether or not the detected value of the internal sensor is within a predetermined range.

7. The discrimination device according to claim 6, wherein the internal sensor includes a pressure sensor for measuring atmospheric pressure, the pressure inside the housing is set to a predetermined pressure when the housing is sealed, and the discrimination unit determines that the airtightness has been lost when the pressure detected by the internal sensor falls outside a predetermined pressure range.

8. The discrimination device according to claim 6, wherein the internal sensor includes a gas sensor for detecting the concentration of a specific gas, the specific gas is filled inside the housing such that the concentration of the specific gas inside the housing is a predetermined concentration when the housing is sealed, and the discrimination unit determines that the airtightness has been lost when the concentration of the specific gas detected by the internal sensor falls outside a predetermined concentration range.

9. The discrimination device according to claim 6, wherein the internal sensor includes a humidity sensor for detecting humidity, the humidity inside the housing is set in advance so that when the housing is sealed, the humidity inside the housing is a predetermined humidity, and the discrimination unit determines that the airtightness has been lost when the humidity detected by the internal sensor falls outside a predetermined humidity range.

10. The discrimination device according to claim 6, wherein the internal sensor includes a light receiving sensor for measuring the amount of light, the housing is made of a material that does not transmit light from the outside, and the housing is sealed so as not to allow light from the outside to pass through, and the discrimination unit determines that the airtightness has been lost when the amount of light measured by the light receiving sensor exceeds a predetermined light amount threshold.

11. The housing is provided with an explosion-proof valve (50a) for the housing that opens when the air pressure inside the housing exceeds a predetermined value, and the light receiving sensor is positioned opposite the explosion-proof valve for the housing, as described in claim 10.

12. The discrimination device according to claim 10, further comprising a light-emitting element (48) positioned opposite the light-receiving sensor, wherein the discrimination unit, when the light-emitting element is not emitting light, causes the light-emitting element to emit light when the amount of light measured by the light-receiving sensor is less than a light intensity threshold, and determines that the device is normal if the amount of light measured by the light-receiving sensor is equal to or greater than the light intensity threshold, while determining that the device is abnormal if the amount of light measured by the light-receiving sensor is less than the light intensity threshold.

13. The discrimination device according to any one of claims 1 to 5, wherein the discrimination unit acquires a physical quantity related to the internal state at predetermined intervals, calculates the rate of change of the physical quantity from the acquired physical quantity related to the internal state, and determines whether or not an abnormality has occurred inside the housing based on whether or not the rate of change of the physical quantity is equal to or greater than a predetermined rate threshold.

14. The discrimination device according to any one of claims 1 to 5, wherein the discrimination unit is configured to repeatedly perform the acquisition of the detected value and the determination of airtightness at a predetermined discrimination cycle, and the discrimination unit shortens the discrimination cycle compared to normal when an impact is detected by the impact detection sensor or when an acceleration of a predetermined value or more is detected by the acceleration sensor.

15. The discrimination device according to any one of claims 1 to 5, wherein the internal sensor is a thermal runaway detection sensor for detecting thermal runaway inside the battery pack.

16. A discrimination program to be performed by a discrimination device (31) for determining the airtightness of a battery pack (11) having a housing (50) for housing batteries (20, 21, 22), comprising: a discrimination step of obtaining detection values ​​from one or more internal sensors that detect physical quantities related to the internal state of the housing, and determining the airtightness based on the obtained detection values; and a notification step of notifying the device if it is determined in the discrimination step that the housing is not airtight.

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