JP7328614B2 - Abnormality detection device for battery pack - Google Patents

Description

The present invention relates to a battery pack abnormality detection device for detecting an abnormality in a battery pack of a vehicle.

2. Description of the Related Art An electric vehicle such as an electric vehicle or a hybrid vehicle having an electric motor (motor) as a power source is equipped with a battery pack for supplying electric power to the electric motor. A battery pack includes a plurality of battery cells and a case that accommodates the plurality of battery cells, and the battery cells are electrically connected within the case.

Each battery cell has various structures. For example, there is a case in which power generation elements including a positive electrode plate, a negative electrode plate, and a separator are housed in a container together with an electrolytic solution, and the container is sealed with a lid member. In such a battery cell, for example, if foreign matter such as metal dust is mixed in the container, the foreign matter may cause an internal short circuit.

When an internal short circuit occurs, the temperature inside the container rises, gas is generated, and the pressure inside the container rises. For this reason, the battery cell is generally provided with a safety valve that opens when the pressure inside the container rises to a predetermined value, thereby suppressing the explosion due to the pressure rise.

In a battery pack in which a plurality of battery cells are sealed in a container, when a safety valve opens due to an internal short circuit, the heat of the battery cell causes the internal pressure to rise even in adjacent normal battery cells. As a result, the safety valve opens (so-called thermal chain). Therefore, in the battery pack, it is preferable to appropriately detect an abnormality in each battery cell (safety valve opening) and take early action.

Various techniques have been proposed for detecting opening of a safety valve (increase in internal pressure) in a battery cell (see, for example, Patent Document 1). The technique described in Patent Document 1 detects the concentration of a specific substance contained in the gas when the safety valve of the battery cell is opened and the gas is released from the inside. If this concentration is equal to or higher than a predetermined value, it is determined that the safety valve has opened.

However, for example, if the degree of airtightness of the battery pack is low, it is difficult to accurately detect the concentration of the specific substance.

Japanese Patent No. 6122498

SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery pack abnormality detection device capable of more reliably detecting an abnormality in a battery cell (opening of a safety valve). .

A first aspect of the present invention for solving the above problems is an abnormality detection device for detecting an abnormality in a battery pack in which a plurality of battery cells are housed in a battery case and provided with a safety valve that opens when internal pressure rises. an exhaust pipe into which the gas discharged from the safety valve of the battery cell flows; a gas flow meter that measures the flow rate of the gas flowing through the exhaust pipe; an abnormality detection means for detecting an abnormality in the battery cells, wherein the exhaust pipe is provided for each of the plurality of battery cells, the gas flow meter is provided for each exhaust pipe, and the abnormality detection means comprises: The battery pack abnormality detection device is characterized in that the battery cell abnormality is detected based on the flow rate measured by each of the gas flowmeters for each of the battery cells.

In the first mode, the air in the battery case containing the gas discharged from the safety valve is caused to flow into the exhaust pipe. With such a configuration, even if the amount of the gas is small, the gas flows in the exhaust pipe, and the flow rate of the gas can be easily measured by the gas flowmeter. Then, when the gas flowmeter detects a flow rate equal to or greater than a predetermined value, it is possible to detect an abnormality in the battery cell. An exhaust pipe is provided for each battery cell, and the flow rate of gas is measured by a gas flow meter in each exhaust pipe. Therefore, a plurality of battery cells can be individually monitored. Therefore, the abnormal battery cell can be specified among the plurality of battery cells.

A second aspect of the present invention is the battery pack abnormality detection device according to the first aspect, wherein the battery case is provided with an opening, the exhaust pipe is arranged outside the battery case, The battery pack abnormality detection device is characterized in that it is connected to the opening.

In the second aspect, a plurality of battery cells can be collectively monitored by an exhaust pipe and a gas flow meter. Therefore, it is possible to simplify the configuration of the abnormality detection device and reduce the cost.

According to the present invention, there is provided a battery pack abnormality detection device capable of more reliably detecting an abnormality in a battery cell.

1 is a schematic diagram of an abnormality detection device according to Embodiment 1. FIG. 4 is a flow showing the operation of the abnormality detection device according to Embodiment 1; FIG. 5 is a schematic diagram of an abnormality detection device according to Embodiment 2; FIG. 11 is a schematic diagram of an abnormality detection device according to Embodiment 3;

<Embodiment 1>
A battery pack abnormality detection device will be described with reference to FIG.
As shown in FIG. 1, an abnormality detection device 10 of the present embodiment detects an abnormality in a battery pack 1 mounted on an electric vehicle. The battery pack 1 includes a battery case 2 provided below the floor of an electric vehicle (not shown).

The battery case 2 is a box-shaped member that accommodates the battery cells 3 , and multiple battery cells 3 are modularized and accommodated inside.

Each battery cell 3 is, for example, a sealed secondary battery such as a lithium ion battery. Although not shown, the battery cell 3 includes a container 4 and a lid member 5 for sealing the container 4, and an electrode body including a positive electrode plate, a negative electrode plate and a separator inside the container 4 (none of them are shown). is housed with the electrolyte. Since the electrode body has a well-known structure, description thereof is omitted here.

The lid member 5 is provided with a positive electrode terminal and a negative electrode terminal (none of which are shown) that are connected to the positive electrode plate or the negative electrode plate of the electrode assembly housed in the container 4 , respectively. The lid member is further provided with a safety valve 6 between the positive terminal and the negative terminal.

The safety valve 6 is formed relatively weaker than other parts of the lid member 5. For example, when an internal short circuit occurs in the container 4, the internal pressure of the container 4 reaches a predetermined value. Then, the valve is configured to open. As a result, even if the internal pressure of the container 4 rises, the gas inside the container 4 is ejected to the outside from the opened safety valve 6 . Therefore, bursting of the container 4 due to an increase in internal pressure can be suppressed.

Further, the battery case 2 is provided with an opening 11 at the top. An exhaust pipe 12 is connected to the opening 11 . The internal space of the battery case 2 of the present embodiment is hermetically sealed, and communicates with the outside only through the opening 11 and the exhaust pipe 12 .

The exhaust pipe 12 is a member that forms a passage into which gas discharged from a safety valve (not shown) of the battery cell 3 flows. Specifically, the exhaust pipe 12 is arranged outside the battery case 2 and has one end connected to the opening 11 . With such a configuration, the gas discharged from the battery cell 3 flows into the exhaust pipe 12 and is discharged to the outside of the battery case 2 . The material and shape of the exhaust pipe 12 are not particularly limited.

A gas flow meter 13 is provided in the middle of the exhaust pipe 12 . The gas flowmeter 13 is a device that measures the flow rate of the gas that flows from the inside of the battery case 2 toward the outside in the exhaust pipe 12 . A known device can be applied to the gas flowmeter 13, and therefore a detailed description of the configuration is omitted. The gas flowmeter 13 is also connected to the control device 15 and transmits to the control device 15 an electrical signal representing the measured flow rate of the gas.

A check valve 14 is provided in the exhaust pipe 12 downstream of the gas flow meter 13 (opposite to the opening 11 ). The check valve 14 is arranged so as to allow the gas to flow only from the inside of the battery case 2 to the outside, and not vice versa.

The control device 15 is an ECU (Electronic Control Unit) mounted on the electric vehicle, and includes a CPU, a ROM that stores and stores control programs, a RAM as an operating area for the control programs, and an EEPROM that rewritably holds various data. , an interface section for interfacing with peripheral circuits, and the like. The control device 15 realizes various controls such as running, braking, and charging/discharging of the electric vehicle by controlling each part of the vehicle via the interface unit.

As one function of the control device 15 , abnormality detection of the battery cell 3 is performed based on the flow rate measured by the gas flow meter 13 . The function of performing this abnormality detection is realized by the abnormality detection section 16 implemented as a control program. The abnormality detection unit 16 is an example of the abnormality detection means described in the claims.

As described above, the interior of the battery case 2 is in a sealed state and communicates with the outside only through the opening 11 and the exhaust pipe 12 . A check valve 14 is provided in the exhaust pipe 12 to prevent air from flowing into the exhaust pipe 12 from the outside. Therefore, when the safety valve 6 of the battery cell 3 is not open, the air inside the battery case 2 hardly flows, and the flow rate measured by the gas flow meter 13 is very small.

On the other hand, when the safety valve 6 of the battery cell 3 is opened and the gas is discharged, the gas (including the air originally present inside the battery case 2) flows into the exhaust pipe 12 through the opening 11. Then, the gas flow rate is measured by the gas flow meter 13 . Since the gas passes through the check valve 14 and is discharged to the outside, the flow rate of the gas gradually approaches zero. That is, the gas flow rate measured by the gas flow meter 13 is almost zero when the safety valve 6 is closed, and rises in a short period of time when the safety valve 6 opens, and then returns to the original state.

In the abnormality detection unit 16, a predetermined value is set to a flow rate that cannot be assumed as the flow rate of the gas when the safety valve 6 is closed. Then, the abnormality detection unit 16 detects a state in which the safety valve 6 is open, ie, an abnormality in the battery cell 3, when the flow rate of the gas rises and reaches or exceeds a predetermined value.

There are various methods for determining whether the flow rate of gas has reached or exceeded a predetermined value. For example, the number of times the gas flow rate exceeds a predetermined value is counted, and if the number of times is a predetermined number within a predetermined period of time, it is determined that the battery cell 3 is abnormal. Alternatively, it may be determined that the battery cell 3 is abnormal if the differential value of the flow rate of the gas is equal to or greater than a predetermined value. In any case, the abnormality of the battery cell 3 can be determined based on the gas flow rate.

Also, the predetermined value described above can be obtained by actual measurement or simulation. For example, the predetermined value can be obtained by placing the battery pack 1 in an environment where the safety valve 6 is open and measuring the flow rate of the gas when the safety valve 6 is actually opened by the gas flow meter 13 .

Further, the abnormality detection device 10 may be provided with an alarm system for warning the passenger that an abnormality has occurred when the abnormality detection unit 16 detects an abnormality in the battery cell 3 . As an alarm system, for example, a device for transmitting information such as a liquid crystal display and a speaker provided in an electric vehicle, and information indicating that an abnormality has occurred in the battery cell 3 (characters, images, graphics, voice etc.) can be mentioned.

Moreover, the abnormality detection of the battery cell 3 by the abnormality detection unit 16 may always function, or may function when a specific condition is satisfied. A state in which the abnormality detection unit 16 is detecting an abnormality in the battery cell 3 is called a monitoring mode, and a state in which the abnormality detection is not being performed is called a non-monitoring mode. Determination for switching between the monitoring mode and the non-monitoring mode will be described with reference to FIG.

First, the abnormality detection unit 16 determines whether the ignition switch of the vehicle is ON (step S1). If the ignition switch is ON (step S1: Yes), the abnormality detector 16 shifts to the monitoring mode (step S5).

If the ignition switch is off (step S1: No), it is determined whether a passenger is in the vehicle (step S2). Whether an occupant is on the vehicle can be obtained, for example, by a seat sensor that detects whether the occupant is on the vehicle. In addition, it is possible to determine whether or not a passenger appears in the vehicle by analyzing an image obtained by a camera provided in the vehicle.

If the passenger appears (step S2: Yes), the abnormality detection unit 16 shifts to the monitoring mode (step S5). Even if the ignition switch is turned off, if a passenger appears in the vehicle, the vehicle enters the monitoring mode, thereby further enhancing safety.

If the passenger does not appear (step S2: No), the abnormality detection unit 16 determines whether the manual switch is on (step S3). The manual switch is a switch for forcibly shifting the abnormality detection unit 16 to the monitoring mode. If the manual switch is on (step S3: Yes), the abnormality detector 16 shifts to the monitoring mode (step S5).

If the manual switch is off (step S3: No), the abnormality detector 16 shifts to the non-monitoring mode (step S4).

By setting the monitoring mode when such specific conditions (steps S1 to S3) are established, it is possible to detect an abnormality in the battery cell 3 when it is necessary to ensure the safety of the occupants. As described above, the monitor mode may be set when any of the specific conditions are satisfied, or the constant monitor mode may be set regardless of the specific conditions.

The battery pack abnormality detection device 10 described above causes the air in the battery case 2 containing the gas discharged from the safety valve 6 to flow into the exhaust pipe 12 . With such a configuration, even if the amount of the gas is small, the gas flows in the exhaust pipe 12 and the gas flow rate can be easily measured by the gas flowmeter 13 . Then, when the gas flow meter 13 detects a flow rate equal to or greater than a predetermined value, an abnormality in the battery cell 3 can be detected.

In the conventional technology, the concentration of the specific substance contained in the gas discharged from the safety valve 6 of the battery cell 3 is detected. Cheap. Therefore, it is difficult to accurately detect the concentration of the specific substance and detect an abnormality in the battery cell 3 based on the concentration.

On the other hand, the abnormality detection device 10 of the present embodiment targets the flow rate of the air in the battery case 2 containing gas discharged from the battery cells 3 . Therefore, regardless of the amount of the specific substance, the flow rate of the gas can be detected satisfactorily, and the abnormality of the battery cell 3 can be detected more reliably based on the flow rate.

Further, in the abnormality detection device 10 of the present embodiment, the exhaust pipe 12 is provided outside the battery case 2 and connected to the opening 11 . According to such an abnormality detection device 10 , a plurality of battery cells 3 can be collectively monitored by one exhaust pipe 12 and one gas flowmeter 13 . Therefore, it is possible to simplify the configuration of the abnormality detection device 10 and reduce the cost.

<Embodiment 2>
An abnormality detection device 10 according to the second embodiment will be described with reference to FIG. In addition, the same code|symbol is attached|subjected to the same thing as Embodiment 1, and the overlapping description is abbreviate|omitted.

As shown in FIG. 3, unlike the first embodiment, the battery case 2 of the abnormality detection device 10 does not have an opening 11 and is closed.

Inside the battery case 2 , a gas collecting member 17 is arranged above the plurality of battery cells 3 . The gas collecting member 17 is a box-shaped member with one side open. The opening of the gas collecting member 17 is sized and shaped to completely cover the plurality of battery cells 3 , and faces the safety valve 6 side of the battery pack 1 .

By arranging such a gas collecting member 17 above the battery cell 3 , the gas discharged from the safety valve 6 of the battery cell 3 is collected inside the gas collecting member 17 .

An opening 18 is provided at the bottom of the gas collecting member 17 , and the exhaust pipe 12 is connected to the opening 18 . The exhaust pipe 12 , the gas flow meter 13 and the check valve 14 of this embodiment are arranged outside the gas collection member 17 and inside the battery case 2 .

As in the first embodiment, the battery pack abnormality detection device 10 described above can detect an abnormality in the battery cell 3 when the gas flow meter 13 detects a flow rate equal to or greater than a predetermined value.

In addition, by providing the gas collecting member 17 , a plurality of battery cells 3 can be collectively monitored by one exhaust pipe 12 and one gas flowmeter 13 . Therefore, it is possible to simplify the configuration of the abnormality detection device 10 and reduce the cost.

Furthermore, since the exhaust pipe 12 and the gas flow meter 13 are arranged inside the battery case 2, they are less likely to be affected by outside air. Therefore, the gas flowmeter 13 can accurately measure the flow rate of the gas originating from the battery cell 3, and the abnormality determination of the battery cell 3 based on this flow rate can be made more accurate.

Note that the gas collecting member 17 is common to all of the plurality of battery cells 3, but is not limited to such a configuration. For example, a plurality of gas collecting members 17 may be provided, a plurality of battery cells 3 may be divided into several groups, and each gas collecting member 17 may be assigned to each group. Also, the exhaust pipe 12 and the gas flow meter 13 are accommodated inside the battery case 2, but the configuration is not limited to this. For example, the exhaust pipe 12 may have one end connected to the gas collection member 17 inside the battery case 2 and the other end exposed to the outside of the battery case 2 . The gas flowmeter 13 and the check valve 14 are not particularly limited in their mounting positions, and may be inside or outside the battery case 2 .

<Embodiment 3>
An abnormality detection device 10 according to the third embodiment will be described with reference to FIG. In addition, the same code|symbol is attached|subjected to the same thing as Embodiment 1 and Embodiment 2, and the overlapping description is abbreviate|omitted.

As shown in FIG. 4 , the abnormality detection device 10 is provided with a plurality of exhaust pipes 12 for each battery cell 3 . In the figure, illustration of the battery case 2 is omitted, and only one battery cell 3 and one exhaust pipe 12 are shown.

Specifically, each exhaust pipe 12 is connected to each battery cell 3 , and the safety valve 6 is accommodated in the exhaust pipe 12 . A gas flow meter 13 is provided for each exhaust pipe 12 . The gas flow rate measured by each gas flow meter 13 is transmitted to the control device 15 .

As in the first embodiment, the battery pack abnormality detection device 10 described above can detect an abnormality in the battery cell 3 when the gas flow meter 13 detects a flow rate equal to or greater than a predetermined value.

Further, an exhaust pipe 12 is provided for each of the battery cells 3 , and the gas flow rate is measured by a gas flow meter 13 in each exhaust pipe 12 . Therefore, a plurality of battery cells 3 can be individually monitored. Therefore, the abnormal battery cell 3 can be specified among the plurality of battery cells 3 .

The exhaust pipe 12 may be wholly inside the battery case 2 or partly exposed to the outside of the battery case 2 . Moreover, the gas flow meter 13 and the check valve 14 are not particularly limited in their mounting positions, and may be inside or outside the battery case 2 .

<Other embodiments>
Although one embodiment of the present invention has been described above, the present invention is, of course, not limited to the above-described embodiment.

For example, the battery pack 1 described in each embodiment has battery cells 3 housed in a sealed battery case 2, but is not limited to this. For example, the battery case 2 may be a non-sealed battery case 2 provided with openings through which air for cooling the battery cells 3 circulates. Even in the battery pack 1 having such a battery case 2, the flow rate can be measured by the gas flow meter 13 in the exhaust pipe 12, which is not easily affected by the outside air, and the abnormality of the battery cell 3 based on the flow rate can be detected. Judgment can be made.

Moreover, although the configuration in which the battery pack 1 is arranged below the floor surface of the vehicle has been described, the configuration is not limited to this, and the battery pack 1 may be arranged in the vehicle interior. In this case, it is preferable to apply the abnormality detection device 10 configured as in the second embodiment so that the gas discharged from the safety valve 6 does not leak into the passenger compartment. Furthermore, the battery pack 1 is not limited to being applied to an electric vehicle, and the abnormality detection device 10 of the present invention can be applied to a battery pack 1 used for other purposes.

Although the abnormality detection unit 16, which is a program executed by the control device 15, has been exemplified as the abnormality detection means, the abnormality detection means is not limited to this. The abnormality detection means may be, for example, an electronic circuit that achieves a function equivalent to that of the abnormality detection section 16 .

Also, although the exhaust pipe 12 is provided with the check valve 14, it is not an essential configuration. For example, in a configuration like the second embodiment in which the exhaust pipe 12 is arranged inside the battery case 2, the check valve 14 may be omitted.

Reference Signs List 1 battery pack 2 battery case 3 battery cell 6 safety valve 10 abnormality detection device 11 opening 12 exhaust pipe 13 gas flow meter 16 abnormality detection unit (abnormality detection means ), 17... gas collecting member

Claims (2)

An abnormality detection device for detecting an abnormality in a battery pack in which a plurality of battery cells, which are provided with a safety valve that opens due to an increase in internal pressure, is accommodated in a battery case,
an exhaust pipe into which gas discharged from the safety valve of the battery cell flows;
a gas flow meter for measuring the flow rate of gas flowing through the exhaust pipe;
an abnormality detection means for detecting an abnormality in the battery cell based on the flow rate measured by the gas flow meter ;
The exhaust pipe is provided for each of the plurality of battery cells,
The gas flow meter is provided for each exhaust pipe,
The abnormality detection means detects an abnormality of the battery cell based on the flow rate measured by each gas flowmeter for each battery cell.
An abnormality detection device for a battery pack characterized by: In the battery pack abnormality detection device according to claim 1,
The battery case is provided with an opening,
The abnormality detection device for a battery pack, wherein the exhaust pipe is arranged outside the battery case and connected to the opening.

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