Apparatus and method for estimating internal gas in secondary battery

Abstract

To estimate a component of and the amount of gas generated inside a secondary battery while reducing a cost.SOLUTION: A device of estimating gas inside a secondary battery according to an embodiment of a present disclosure, for estimating the amount of and a component of an internal gas generated inside the secondary battery which can be charged and discharged, includes: one or more processors; and one or more memories electrically connected to the processor(s). Each processor detects the presence / absence of a gas generation period where the secondary battery is located in an overcharge state of the secondary battery exceeding at least an appropriate use limit and a high temperature state of the secondary battery exceeding the appropriate use limit, and estimates the amount of and a component of the internal gas on the basis of an integration result of a voltage value of the secondary battery in the gas generation period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a technique for estimating internal gas in a secondary battery, such as a lithium-ion secondary battery. [Background technology]

[0002] In modern society, automobiles are an indispensable means of transportation, and various vehicles travel on the roads in our daily lives. In recent years, in order to make depleting resources sustainable, electric vehicles equipped with rechargeable secondary batteries such as lead-acid batteries and lithium-ion secondary batteries and drive motors are becoming mainstream.

[0003] Secondary batteries can become filled with gas when placed in an abnormal environment, such as when overcharged or overheated. To address this issue, Patent Document 1, for example, proposes a structure that safely releases gas generated in the event of an abnormality in a battery made up of secondary batteries to the outside of the vehicle through an on-board catalytic converter. Similarly, Patent Document 2 discloses a method that combines blocking, exhausting, and ventilation depending on the vehicle condition and the gas concentration to prevent gas generated inside the battery from entering the vehicle cabin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-198738 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-6153 Summary of the Invention [Problem to be solved by the invention]

[0005] However, current technologies, including those disclosed in the above-mentioned patent documents, do not adequately meet market needs, and the following problems remain. For example, the above-mentioned Patent Document 1 does not address the components of the gas that fills the battery, and is unable to provide detailed support for the components of the gas released from the battery.On the other hand, Patent Document 2 uses a concentration sensor to detect the concentration of gas generated inside the battery, which increases the number of parts installed in the vehicle and poses the problem of the need for measures and maintenance in case of sensor failure.

[0006] The present disclosure has been made in consideration of the above-mentioned problems as an example, and aims to provide an internal gas estimation device for a secondary battery that can estimate the components and amount of gas generated inside the secondary battery while further reducing costs. [Means for solving the problem]

[0007] In order to solve the above problems, the internal gas estimation device for a secondary battery disclosed herein is an internal gas estimation device that estimates the amount and composition of internal gas generated inside a rechargeable secondary battery, and includes one or more processors and one or more memories electrically connected to the processors, and the processor detects whether or not there is a gas generation period in which the secondary battery is placed in an overcharged state that exceeds at least the appropriate usage upper limit and a high temperature state of the secondary battery that exceeds the appropriate usage upper limit, and estimates the amount and composition of the internal gas based on the integration result of the voltage value of the secondary battery during the gas generation period.

[0008] In order to solve the above problem, the vehicle of the present disclosure includes an engine that drives the vehicle, a secondary battery that is used at least to supply power to on-board equipment installed in the vehicle, a gas introduction pipe that connects the intake path to the engine and the secondary battery, a first opening / closing valve that controls the opening and closing of the gas introduction pipe, and an internal gas estimation device of the present disclosure. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to estimate the components and amount of gas generated inside a secondary battery while further reducing costs. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing a vehicle according to an embodiment; [Figure 2] 1 is a functional block diagram including an internal gas estimation device for a secondary battery according to an embodiment. [Figure 3] 3 is a flowchart showing a main flow of a method for estimating internal gas in a secondary battery according to an embodiment. [Figure 4] 4 is a flowchart showing a gas estimation and storage process in the method for estimating internal gas in a secondary battery according to the embodiment. [Figure 5] 5 is a schematic diagram for explaining an integral process in the method for estimating internal gas in a secondary battery according to an embodiment. FIG. [Figure 6] 3 is a schematic diagram of table data showing the cumulative gas amount for each gas component used in the method for estimating internal gas in a secondary battery according to the embodiment; FIG. [Figure 7] 4 is a flowchart showing a gas discharge process in the method for estimating internal gas in a secondary battery according to the embodiment. [Figure 8] FIG. 10 is a schematic diagram of table data showing cumulative gas amounts for each gas component according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, preferred embodiments for carrying out the present disclosure will be described. Furthermore, configurations other than those detailed below can be implemented by appropriately supplementing elemental technologies and configurations related to vehicles equipped with publicly known secondary battery systems, including those described in the above-mentioned patent documents.

[0012] <Vehicle 100> First, the configuration of a vehicle 100 according to a preferred embodiment of the present disclosure will be described with reference to Fig. 1. The vehicle 100 according to this embodiment is configured to include a control device 10, a secondary battery 20, an engine 30, a load 40, a piping system 50, and sensors SR, each of which will be described later. Examples of such a vehicle 100 include various known hybrid vehicles equipped with a known inverter or electric motor as the load 40.

[0013] [Control device 10] Next, the configuration of the control device 10 in the vehicle 100 of this embodiment will be described with reference to FIG. The control device 10 of this embodiment is an ECU configured with one or more known processors and one or more known memories electrically connected to the processors, and functions as an internal gas estimation device that estimates the amount and composition of internal gas generated inside the chargeable and dischargeable secondary battery 20. Hereinafter, this control device 10 will be described as an internal gas estimation device 10.

[0014] 2, the internal gas estimation device 10 of this embodiment includes a current measurement unit 11, a voltage measurement unit 12, a battery temperature measurement unit 13, an internal gas estimation unit 14, an emission control unit 15, and a notification control unit 16, each configured with a program that realizes a desired function. The internal gas estimation device 10 is configured to be able to communicate with other known on-board ECUs, such as a hybrid control ECU or an engine control ECU, that are mounted on the vehicle 100. Alternatively, the internal gas estimation device 10 may be incorporated as one function within the hybrid control ECU or the charge control ECU.

[0015] As shown in the figure, the internal gas estimation device 10 of this embodiment may be configured to be connectable to a known external network NET, such as the Internet, via a known communication device CD. Note that the external network NET is not limited to the Internet, but also includes, for example, a known information communication network that allows various information to be transmitted and received between vehicles via wireless communication.

[0016] The internal gas estimation device 10 is configured to receive various detection signals from sensors SR mounted on the vehicle 100. Examples of such sensors SR include a known battery temperature sensor SR1 capable of measuring the battery temperature of the secondary battery 20, and a known current sensor SR2 and voltage sensor SR3 provided between the secondary battery 20 and the load 40, as shown in Fig. 1. In addition to the above-mentioned sensors, the sensors SR may also include various known in-vehicle sensors such as an outside air temperature sensor and a vehicle speed sensor that are normally mounted on the vehicle 100.

[0017] Furthermore, the internal gas estimation device 10 is electrically connected to a known notification device DD mounted on each vehicle 100, and can present information such as the state of the secondary battery 20 to the occupants via this notification device DD. Examples of such notification device DD include a known in-vehicle speaker SP and an in-vehicle display DP mounted on the vehicle 100.

[0018] The internal gas estimation device 10 may be configured to be capable of communicating with a known storage device MR such as a hard disk or SSD (solid state drive). The storage device MR of this embodiment may store various programs capable of executing the internal gas estimation method described below. The storage device MR may be mounted on the vehicle 100, or may be provided as an external server (such as a cloud server) outside the vehicle and accessible via the external network NET.

[0019] The current measurement unit 11 has a function of measuring the value of a current flowing through the secondary battery 20. More specifically, the current measurement unit 11 measures the value of a current flowing through the secondary battery 20 connected to the load 40 via the current sensor SR2 described above.

[0020] The voltage measurement unit 12 has a function of measuring the voltage value between the terminals of the secondary battery 20. More specifically, the voltage measurement unit 12 measures the voltage value of the secondary battery 20 connected to the load 40 via the voltage sensor SR3 described above.

[0021] The battery temperature measurement unit 13 has a function of measuring the temperature of the secondary battery 20. More specifically, the battery temperature measurement unit 13 measures the temperature of the secondary battery 20 connected to the load 40 via the above-mentioned battery temperature sensor SR1.

[0022] The internal gas estimation unit 14 has a function of estimating the components and amount of internal gas generated inside the secondary battery 20. As will be described later, the internal gas estimation unit 14 estimates the components and amount of gas generated inside the secondary battery 20 during either an overcharged state or a high-temperature state of the secondary battery 20.

[0023] The components and amounts of the gases described above can be obtained in advance by experiment or simulation using the following method, for example. That is, according to publicly available literature such as "Elucidating the Degradation Mechanism of Lithium-Ion Batteries, Research Report: T99040," published by the Central Research Institute of Electric Power Industry in June 2000, it is shown that the chemical reaction of the electrolyte decomposition in lithium-ion batteries varies depending on the voltage or temperature. Furthermore, "Elucidating the Degradation Mechanism of Lithium-Ion Batteries, Research Report: T99040" also provides examples of the gas compositions generated during normal operating voltage, overcharge, and overdischarge tests in Table 2. These literatures clearly show that the gas compositions generated inside lithium-ion batteries vary depending on the voltage value.

[0024] Therefore, by understanding the electrolyte components of the lithium-ion secondary battery used, whether an overcharged state has occurred, whether a high temperature state has occurred, and the voltage value of the secondary battery in these states, the components of the gas generated in the secondary battery can be identified through prior experiments and simulations, since decomposition of the electrolyte is closely related to the battery voltage and elapsed time.Furthermore, the amount of gas generated at that time can be determined in advance by the above-mentioned experiments and simulations, and the amount of gas generated at each voltage value can be determined in advance.

[0025] In this embodiment, the "overcharged state" refers to a state in which the upper limit voltage (such as a rated voltage) at which the secondary battery can be stably and appropriately used is exceeded, which is predetermined by the manufacturer, etc. In this embodiment, the overcharged state is determined based on the voltage value, but the parameter used to determine the overcharged state may be the state of charge (SOC) of the secondary battery or the capacity (Ah) of the secondary battery instead of the voltage value.

[0026] Similarly, in this embodiment, the "high temperature state" refers to a state in which the temperature exceeds the upper limit temperature at which the secondary battery can be stably and properly used, which is predetermined by the manufacturer, etc. In this embodiment, the high temperature state is determined based on the temperature at which the secondary battery can safely operate, but the temperature at which the electrolyte begins to decompose may be used as the standard for determining the high temperature state instead of the above-mentioned temperature at which the secondary battery can safely operate.

[0027] In this way, the gas component table data during overcharge, which specifies the components and amounts of internal gas generated inside the secondary battery in an overcharged state for each voltage value, obtained in advance by experiment or simulation, is stored in the memory device MR. Similarly, the gas component table data during high temperature conditions, which specifies the components and amounts of internal gas generated inside the secondary battery in a high temperature condition for each voltage value, obtained in advance by experiment or simulation, is stored in the memory device MR. This enables the internal gas estimation unit 14 to estimate the amount and components of the internal gas generated in the secondary battery by comparing the integral amount per unit time described below during either the overcharged state or the high temperature state and the voltage value (average voltage) at that time with the gas component table data stored in advance.

[0028] Furthermore, the internal gas estimation unit 14 of this embodiment has a function of integrating and storing the components and amounts of gas generated inside the secondary battery 20. As will be described later, the internal gas estimation unit 14 integrates the area of ​​the range exceeding the upper limit of voltage for proper use in a graph in which the horizontal axis represents the time during which the battery is overcharged beyond the upper limit of proper use and the vertical axis represents the voltage value of the secondary battery 20. At this time, as illustrated in FIG. 6 and the like, the internal gas estimation unit 14 preferably classifies the estimated amount and components of the internal gas in the secondary battery 20, integrates and stores the accumulated amounts for each component.

[0029] The discharge control unit 15 has a function of determining the discharge mode of the internal gas stored in the secondary battery 20 based on the cumulative amount of each component estimated above. Furthermore, the exhaust control unit 15 determines a method for exhausting the internal gas based on the exhaust mode determined above. More specifically, the exhaust control unit 15 can execute a process for introducing the internal gas generated in the secondary battery into the intake path to the engine as a combustion assist gas. Furthermore, the exhaust control unit 15 can execute a process for exhausting the internal gas outside the vehicle without introducing it into the intake path to the engine.

[0030] The notification control unit 16 has a function of controlling notifications via the above-mentioned in-vehicle speaker SP and in-vehicle display DP. For example, the notification control unit 16 can notify the state of the vehicle 100 via the in-vehicle speaker SP or the in-vehicle display DP based on, for example, the determination result of the internal gas estimation unit 14. This allows, for example, passengers of the vehicle 100 to quickly understand the state of the secondary battery 20.

[0031] The secondary battery 20 of this embodiment is used at least to supply power to on-board devices mounted on the vehicle 100. The secondary battery 20 of this embodiment has a function of supplying power to a load 40, which will be described later, and also charging the load 40 with power generated therein as needed. As such a secondary battery 20, various known secondary batteries, such as a lithium-ion secondary battery, a lead-acid battery, or a nickel-metal hydride battery, may be used.

[0032] The engine 30 drives the vehicle 100. The engine 30 of this embodiment can be, for example, any of a variety of known engines that obtain power through combustion of gas, such as a reciprocating engine that generates power by burning gasoline or a gas turbine engine that generates power by burning gas.

[0033] The load 40 can be, for example, various known loads that are mounted on the vehicle and can be driven by power from a secondary battery, such as an electric motor or inverter that can drive the vehicle 100. In this embodiment, a known electric motor that can be mounted on a hybrid vehicle is used as an example of the load 40.

[0034] The piping system 50 includes a gas inlet pipe 51 that connects a known intake path (not shown) to the engine 30 and the secondary battery 20, and a gas exhaust pipe 52 that connects the secondary battery 20 to the outside of the vehicle. The piping system 50 of this embodiment preferably also includes a first on-off valve Va that is provided in the gas inlet pipe 51 and controls the opening and closing of the gas inlet pipe 51, and a second on-off valve Vb that is provided in the gas exhaust pipe 52 and controls the opening and closing of the gas exhaust pipe 52. Various known valves, such as solenoid valves that can control the inflow of gas, can be used for the first on-off valve Va and the second on-off valve Vb.

[0035] <Method for treating internal gas in secondary batteries> Next, a method for treating the internal gas in the secondary battery 20, which is executed by the internal gas estimation device 10 of this embodiment, will be described with reference to FIGS. 3 to 7 as needed.

[0036] First, in step 10 after the system power supply of the vehicle 100 is started, the presence or absence of an abnormality in the secondary battery 20 mounted on the vehicle 100 is detected. More specifically, in this embodiment, an abnormality is determined when the secondary battery 20 falls into at least one of the above-mentioned overcharged state and high temperature state. If the above-mentioned abnormality has not occurred in the secondary battery 20 in step 10, the process proceeds to a gas discharge processing routine in step 40, which will be described later.

[0037] On the other hand, if the above-mentioned abnormality is detected in the secondary battery 20 of the vehicle 100 in step 10, the gas estimation and recording process is executed in the following step 20. The gas estimation and recording process of this embodiment will be described below with reference to FIGS. That is, first, in step 21, it is determined whether or not the battery voltage (voltage value) of the secondary battery 20 exceeds the upper limit voltage. Specifically, the voltage measurement unit 12 of the internal gas estimation device 10 measures the voltage value of the secondary battery 20 via the voltage sensor SR3 described above, and determines whether or not this voltage value exceeds the upper limit voltage.

[0038] If the voltage value of the secondary battery 20 does not exceed the upper limit voltage in step 21, it is determined in the following step 22 whether or not the battery temperature of the secondary battery 20 exceeds the upper limit temperature. Specifically, the battery temperature measurement unit 13 of the internal gas estimation device 10 measures the temperature of the secondary battery 20 via the above-mentioned battery temperature sensor SR1, and determines whether or not this measured temperature exceeds the upper limit temperature. Note that if the temperature of the secondary battery 20 does not exceed the upper limit temperature in step 22, the process proceeds to step 26, as described below.

[0039] If the voltage value of the secondary battery 20 exceeds the upper limit voltage in step 21 or if the temperature of the secondary battery 20 exceeds the upper limit temperature in step 22, the following integration process is executed in step 23. That is, in steps 21 and 22, it is detected whether or not the secondary battery 20 is in an overcharged state that exceeds at least the upper limit of proper use, the high temperature state of the secondary battery 20 that exceeds the upper limit of proper use, and the period of gas generation in which the secondary battery 20 was placed.

[0040] Next, as an example of the integration process in this embodiment, the integration process when the voltage value of the secondary battery 20 exceeds the upper limit voltage will be illustrated with reference to FIG. FIG. 5 is a graph in which the horizontal axis represents time t of the secondary battery 20 and the vertical axis represents the voltage value. As is clear from the figure, at time t1 the voltage value of the secondary battery 20 exceeds the upper limit voltage V1 at which the battery is in an overcharged state, then passes through a maximum voltage value V3, and then at time t2 it again exceeds the upper limit voltage V1 and enters a non-abnormal state. In other words, the period from time t1 to time t2 is the period during which an abnormality occurred in the secondary battery 20 (first overcharge occurrence), and gas is generated within the secondary battery (gas generation period).

[0041] At this time, the internal gas estimation unit 14 estimates the components and amount of the internal gas generated inside the secondary battery 20 during the period from time t1 to time t2 (gas generation period) according to the above-mentioned method. Specifically, in the range exceeding the upper limit voltage V1 at which the overcharge state occurs in the graph above, the internal gas estimation unit 14 first performs integration processing per unit time in step 23. Note that this "unit time" can be set to any time, but may also be a time interval that matches the reaction rate of the electrolyte, for example.

[0042] Next, in step 24, the internal gas estimation unit 14 estimates (calculates) the components and amount of internal gas generated inside the secondary battery 20 based on the integration result per unit time obtained in step 23 and the voltage value (average voltage) within this integration range, and by referring to the gas component table data in an overcharged state obtained in advance through experiments or simulations.

[0043] In other words, since the components and amounts of the internal gas generated in the secondary battery 20 are specifically determined in advance through experiments or simulations for each of a plurality of overvoltage values, the internal gas estimation unit 14 can estimate (calculate) the data that best matches the current conditions as the components and amounts of the internal gas by referring to the gas component table data (comparing it with the reference amount and reference components of the internal gas derived from the voltage value and area stored in advance).

[0044] Next, in step 25, the internal gas estimation unit 14 divides the estimated internal gas amount and components into groups based on the estimated internal gas amount and components, as shown in the cumulative gas data in Figure 6(a), and accumulates the cumulative gas amount and stores it in the above-mentioned memory device MR or the like. After step 25 is completed, the process returns to step 21 to determine whether the battery voltage has exceeded the upper limit voltage. As shown in FIG. 5, in this embodiment, the period from time t1 to time t2 is the gas generation period when the upper limit voltage has been exceeded, and therefore the internal gas estimation unit 14 repeats the processes of steps 23 to 25 described above from time t1 to time t2. Furthermore, the internal gas estimation unit 14 updates the cumulative gas data by going through step 25 each time between time t1 and time t2. As a result, in the section indicated by the diagonal lines from time t1 to time t2 in FIG. 5, the area per unit time is repeatedly calculated through steps 23 to 25, and the gas components and amounts at that time are sequentially reflected in the cumulative gas data.

[0045] In this embodiment, it is preferable to calculate the components and amount of the internal gas each time the above-mentioned overcharge state occurs in the secondary battery 20, add this to the previous cumulative gas amount, and update the cumulative gas data, thereby storing the cumulative gas data in a memory device MR or the like.

[0046] 5, at time t3 after time t2 has elapsed, the voltage value of the secondary battery 20 again exceeds the upper limit voltage V1 at which the battery enters an overcharged state, and then passes through the maximum voltage value V2 before passing the upper limit voltage V1 at time t4, again reaching a non-abnormal state. In other words, the period from time t3 to time t4 is the period during which an abnormality occurred in the secondary battery 20 (the second overcharge occurrence), and gas was generated within the secondary battery (the second gas generation period).

[0047] At this time, the internal gas estimation unit 14 estimates the components and amount of internal gas generated inside the secondary battery 20 during this period, in the same manner as from time t1 to time t2, according to the above-described method. Specifically, the internal gas estimation unit 14 integrates the area per unit time for the range exceeding the upper limit voltage V1 that causes the overcharged state, and repeats the processing of steps 23 to 25 described above for the period from time t3 to time t4 in FIG. 5 (gas generation period).

[0048] Then, based on the integration result per unit time obtained in step 23 and the voltage value (average voltage) within this integration range, the internal gas estimation unit 14 estimates (calculates) the components and amount of internal gas generated inside the secondary battery 20 by referring to the gas component table data in an overcharged state obtained in advance through experiments or simulations.

[0049] Since repeated overcharges cause deterioration of the battery, the amount of reactive components in the electrolyte decreases relatively after the second overcharge. Therefore, the internal gas estimation unit 14 may calculate the components and amount of internal gas by multiplying the amount of gas generated by a deterioration coefficient depending on the degree of deterioration of the secondary battery 20. Such a deterioration coefficient is determined depending on the degree of deterioration of the battery and can be determined by publicly known techniques, experiments, or simulations.

[0050] The internal gas estimation unit 14 preferably adds the components and amount of internal gas generated inside the secondary battery 20 during the period from time t3 to time t4 to the cumulative gas data and updates the data. That is, as shown in Fig. 6(b), after time t4 has passed, the components and amount of internal gas generated in the secondary battery 20 due to the second abnormality are added to the cumulative gas data each time, and the cumulative gas data is updated to the latest cumulative gas amount. In this way, the internal gas estimation unit 14 of this embodiment estimates the amount and components of the internal gas generated in the secondary battery 20 based on the residence time during the gas generation period and the integration result of the battery voltage.

[0051] In step 26 following step 22, it is determined whether the cumulative gas amount has reached a first predetermined amount. Here, the "first predetermined amount" refers to an amount that does not exceed the tolerance of a known exhaust valve (safety valve) provided in secondary battery 20 (i.e., an amount that does not exhaust gas outside the battery). If the cumulative gas amount has not reached the first predetermined amount in step 26, the process returns to step 21 and the above-described process is repeated. 5, the integration process when the voltage value of the secondary battery 20 exceeds the upper limit voltage has been described, but the same process can be performed when the battery temperature of the secondary battery 20 exceeds the upper limit temperature. That is, when the battery temperature of the secondary battery 20 exceeds the upper limit temperature, in step 24, the internal gas estimation unit 14 estimates the components and amount of gas generated inside the secondary battery 20 based on the integration result per unit time and the battery temperature.

[0052] On the other hand, if the cumulative gas amount reaches the first predetermined amount in step 26, the internal gas estimation device 10 executes a gas discharge process in step 40, which will be described next. 7, in the gas discharge process of this embodiment, first, it is determined in step 41A whether or not the cumulative gas amount has exceeded the first predetermined amount. If it is determined in step 41A that the cumulative gas amount has not exceeded the first predetermined amount, the gas discharge process of this embodiment ends. On the other hand, in step 41B, it is determined whether the cumulative gas amount has exceeded a second predetermined value. Here, the "second predetermined amount" refers to an amount of gas that exceeds the tolerance of a known exhaust valve (safety valve) provided in secondary battery 20 and leaks outside the battery, causing a gas leak to be detected. Note that in the determination of step 41B, a known gas detection sensor may also be provided to determine whether the second predetermined value has been exceeded.

[0053] If it is determined in step 41B that the cumulative gas amount has exceeded the second predetermined value, the process is completed in step 44C by shutting off or safely venting the gas leaking from the secondary battery 20, or ventilating the passenger space. Note that the specific means for shutting off or ventilating the leaked gas may be any known method including those described in the patent documents mentioned above.

[0054] On the other hand, if it is determined in step 41B that the cumulative gas amount does not exceed the second predetermined value, it is determined in the following step 42 whether the vehicle 100 is stopped. Specifically, the internal gas estimation device 10 may determine whether the vehicle 100 is stopped based on signals from sensors SR, such as a known vehicle speed sensor or acceleration sensor, mounted on the vehicle 100. If it is determined in step 42 that the vehicle 100 is not stopped, the vehicle 100 is moving, and the process proceeds to step 44C, where the emergency evacuation process is executed.

[0055] If it is determined in step 42 that the vehicle 100 is stopped, it is determined in the following step 43 whether or not the gas components filling the interior of the secondary battery 20 have a high flammable ratio. More specifically, the emission control unit 15 may refer to the cumulative gas data and determine whether or not the flammable ratio is high based on whether or not a predetermined condition is satisfied, such as whether the cumulative gas amount of methane (CH4) is equal to or greater than a predetermined value, or whether the ratio of methane to all gas components is equal to or greater than a predetermined value.

[0056] If it is determined in step 43 that the gas components filling the interior of the secondary battery 20 do not have a high flammable ratio, the discharge control unit 15 proceeds to step 44B and executes a process of discharging the gas inside the secondary battery 20 to the outside. More specifically, the discharge control unit 15 opens the second on-off valve Vb and closes the first on-off valve Va shown in FIG. 1 , and executes a process of discharging the gas inside the secondary battery 20 to the outside of the vehicle via the discharge valve (safety valve) of the secondary battery 20 and the gas discharge pipe 52.

[0057] Furthermore, in step 45B following step 44B, the emission control unit 15 controls the charging and discharging of the secondary battery 20 in the parked vehicle 100 based on the operating conditions previously determined through experiments, simulations, etc., so that the gas components subsequently generated in the secondary battery 20 do not continue to become gases with a high flammability ratio.

[0058] In step 46 following step 45B, the discharge control unit 15 determines whether the accumulated amount of gas in the secondary battery 20 has exceeded the second predetermined amount. If the accumulated amount of gas in the secondary battery 20 has not exceeded the second predetermined amount in step 46, the process returns to step 42 and continues the gas discharge process of this embodiment, thereby forcibly discharging the gas from the secondary battery 20. That is, in this embodiment, when the amount of gas generated inside the secondary battery 20 exceeds the first predetermined amount (a state in which the safety valve is not open but the battery is filled with gas), it is highly likely that the required specifications for the battery will not be met. Therefore, after this point, the process of forcibly discharging the gas and discharging it so that the amount exceeds the second predetermined amount is executed.

[0059] On the other hand, if it is determined in step 43 that the gas components filling the interior of the secondary battery 20 have a high flammable ratio, the exhaust control unit 15 proceeds to step 44A and executes a gas reuse process in which the gas in the secondary battery 20 is sent as auxiliary gas to the engine 30. More specifically, the exhaust control unit 15 opens the first on-off valve Va and closes the second on-off valve Vb shown in FIG. 1 , and executes a process in which the gas in the secondary battery 20 is supplied to the engine 30 via the exhaust valve (safety valve) of the secondary battery 20 and the gas introduction pipe 51. As a result, highly flammable gas is introduced from the secondary battery 20 into the intake path of the engine 30 as a combustion assist gas, making it possible to perform power generation via the engine 30 in an energy-saving and highly efficient manner.

[0060] Furthermore, in step 45A following step 44A, the emission control unit 15 controls the charging and discharging of the secondary battery 20 in the parked vehicle 100 based on the operating conditions previously determined through experiments, simulations, etc., so that the gas components subsequently generated in the secondary battery 20 continue to be gases with a high flammable ratio.

[0061] In this way, the discharge control unit 15 of this embodiment determines the discharge form of the internal gas stored in the secondary battery 20 based on the cumulative amount of each gas component estimated above, and controls the opening and closing of the first opening / closing valve Va and the second opening / closing valve Vb based on the result of this determination. This makes it possible to effectively utilize gas generated inside the secondary battery 20 due to an abnormality therein, or to safely exhaust it outside the vehicle.

[0062] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to such examples. For example, in the above embodiment, the gas discharge process is selected based on one parameter, such as the level of the flammable ratio, in step 43, but the gas discharge process may be selected based on a plurality of parameters.

[0063] That is, as shown in Fig. 8, a first flag indicating flammability and a second flag indicating toxicity may be set for each gas component in the cumulative gas data. In the example of Fig. 8, a "1" is set for the oxygen component, indicating that it is flammable, and a "0" is set for it, indicating that it is not toxic. Similarly, for nitrogen, carbon dioxide, carbon monoxide, methane, etc. shown in Fig. 8, the flammability or toxicity is set to "1" or "0".

[0064] The flammability ratio may be calculated as a percentage using, for example, the components with a flammability flag of "1" as the numerator and the total gas volume as the denominator. Similarly, the toxicity ratio may be calculated as a percentage using, for example, the components with a toxic flag of "1" as the numerator and the total gas volume as the denominator. This makes it possible to easily determine whether the gas accumulated at a certain point in time is more flammable or more toxic.

[0065] As such, it is clear that a person with ordinary knowledge in the field of technology to which this disclosure pertains will attempt further modifications to these embodiments and variations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of this disclosure. [Explanation of symbols]

[0066] 100 vehicles 10 Internal gas estimator 20 Secondary battery 30 Engine 40 Load 50 Piping System SR sensors

Claims

1. An internal gas estimation device for estimating the amount and components of internal gas generated inside a chargeable / dischargeable secondary battery, one or more processors; one or more memories electrically connected to the processor; The processor: detecting whether or not there is a gas generation period in which the secondary battery is placed in an overcharged state exceeding at least an upper limit of proper use and a high temperature state of the secondary battery exceeding the upper limit of proper use; an amount and composition of the internal gas are estimated based on an integration result of the voltage value of the secondary battery during the gas generation period; A device for estimating the internal gas content of secondary batteries.

2. The processor: In a graph having the time of the overcharged state exceeding the appropriate upper limit of use as the horizontal axis and the voltage value of the secondary battery as the vertical axis, an area of ​​a range exceeding the appropriate upper limit of use voltage is integrated; the integrated area and the voltage value of the secondary battery that exceeds the upper limit of proper use are compared with a reference amount and a reference component of the internal gas derived from the voltage value and the area that have been stored in advance, thereby estimating the amount and component of the internal gas generated in the secondary battery; The device for estimating internal gas in a secondary battery according to claim 1 .

3. The processor: Based on the estimated amount and components of the internal gas, the accumulated gas amount is divided into components and accumulated and stored. The device for estimating internal gas in a secondary battery according to claim 2 .

4. The processor: determining a release form of the internal gas stored in the secondary battery based on the cumulative amount of each of the components; and performing a process of introducing the internal gas as a combustion assist gas into an intake path to the engine based on the determined exhaust mode. The device for estimating internal gas in a secondary battery according to claim 3 .

5. an engine that drives the vehicle; a secondary battery used at least to supply power to an in-vehicle device mounted on the vehicle; a gas introduction pipe connecting an intake path to the engine and the secondary battery; a first on-off valve that controls opening and closing of the gas introduction pipe; The internal gas estimation device for the secondary battery according to any one of claims 1 to 4; A vehicle comprising:

6. a gas exhaust pipe connecting the secondary battery to the outside of the vehicle; a second on-off valve that controls opening and closing of the gas exhaust pipe, The internal gas estimation device includes: controlling opening and closing of the first on-off valve and the second on-off valve based on the components of the internal gas; 6. The vehicle of claim 5.

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