Battery pack

Abstract

A wiring part body (20A) that is disconnected when a pressure reducing valve (18A) is opened is provided extending from a case (16) to the pressure reducing valve (18A), and the occurrence of abnormality in a battery pack (10) is detected by detecting disconnection of the wiring part body (20A) by means of a battery monitoring ECU (12) connected to the wiring part body (20A). Since there is no need to provide a pressure sensor for detecting the internal pressure of the case, which has conventionally been required, manufacturing costs can be reduced, and the battery monitoring ECU (12) can advantageously detect the internal pressure of the battery pack (10) on the basis of the disconnection of the wiring part body (20A) as reliably as in the case where the pressure sensor is provided.

Description

Battery pack

[0001] The present invention relates to a battery pack.

[0002] Electric vehicles, such as electric vehicles and hybrid vehicles, are equipped with a battery pack that supplies power to the motor. The battery pack includes a battery pack consisting of multiple battery modules, an electrical unit for controlling the battery pack, and a waterproof and airtight case that houses the battery pack and the electrical unit. The case is equipped with a pressure reducing valve that opens to suppress the increase in internal pressure when high-temperature gases generated during thermal runaway in the battery pack cause the case to rise (see Patent Document 1). In recent years, the United Nations safety standard (UN R100-03) for battery pack safety certification requires that the generation of high-temperature gases generated during thermal runaway in the battery pack be detected and an occupant be notified of a battery pack abnormality. For example, a pressure sensor that detects the internal pressure of the battery pack may be provided, and a battery monitoring ECU (Electronic Control Unit) provided in the battery pack may determine the presence or absence of a battery pack abnormality based on the internal pressure detected by the pressure sensor and notify the occupant.

[0003] Japanese Patent Application Publication No. 2022-103526

[0004] However, with the above configuration, a pressure sensor must be newly provided in addition to the pressure reducing valve, which is disadvantageous in terms of reducing the manufacturing cost of the battery pack. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery pack that is advantageous in terms of reliably detecting the internal pressure of the battery pack while reducing the manufacturing cost.

[0005] To achieve the above object, one embodiment of the present invention provides a battery pack including a case for accommodating a battery pack, and a pressure reducing valve provided in the case that opens when internal pressure of the case increases to suppress the increase in internal pressure, the battery pack further including a wiring main body provided from the case to the pressure reducing valve that is disconnected when the pressure reducing valve opens, and a battery monitoring ECU that detects an abnormality in the battery pack by detecting a disconnection in the wiring main body. One embodiment of the present invention is characterized in that the pressure reducing valve includes an opening provided in the case and a waterproof membrane sealing the opening, the opening of the pressure reducing valve is caused by rupture of the waterproof membrane, and the wiring main body includes a waterproof membrane wiring portion formed in the waterproof membrane that is disconnected when the waterproof membrane ruptures. One embodiment of the present invention is characterized in that the waterproof membrane wiring portion is provided to pass through a center portion of the waterproof membrane, and the waterproof membrane wiring portion includes a connector interposed in the waterproof membrane wiring portion, and the connector is disconnected when the waterproof membrane ruptures. In one embodiment of the present invention, the waterproof membrane wiring unit includes a wiring portion extending from an edge of the waterproof membrane to a center thereof, the wiring unit main body includes a first wiring portion extending from an end of the wiring portion located in the center toward the case, away from the waterproof membrane, a connector is interposed on the first wiring portion, and the connection of the connector is released when the waterproof membrane is ruptured.In one embodiment of the present invention, the pressure reducing valve includes an opening wall portion provided in the case and forming an opening, and a valve body that is constantly biased in a direction to close the opening and moves away from the opening wall to open the opening when internal pressure of the case increases, the wiring unit main body includes a valve body conducting portion provided on the valve body and an opening conducting portion provided on the opening wall and connected to the battery monitoring ECU,In one embodiment of the present invention, the valve element conducting portion is formed around the entire outer periphery of the valve element, and the opening conducting portions are provided separately from each other in the circumferential direction of the opening wall portion, each connected to the battery monitoring ECU, and include a first opening conducting portion and a second opening conducting portion that are respectively connected to the valve element conducting portions when the valve element closes the opening.In one embodiment of the present invention, the wiring portion main body is configured to include a portion formed of a conductive thin film.

[0006] According to one embodiment of the present invention, a wiring main body is provided extending from the case to the pressure reducing valve, and the wiring main body is disconnected when the pressure reducing valve is opened. A battery monitoring ECU connected to the wiring main body detects a disconnection in the wiring main body, thereby detecting an abnormality in the battery pack. This eliminates the need for a pressure sensor for detecting the internal pressure of the case, as was previously required, thereby reducing manufacturing costs and advantageously allowing the battery monitoring ECU to reliably detect the internal pressure of the battery pack by detecting a disconnection in the wiring main body, similar to the case where a pressure sensor is provided. Furthermore, if the pressure reducing valve is opened by rupturing a waterproof membrane sealing an opening in the case, and the waterproof membrane wiring formed in the waterproof membrane is disconnected by the rupture of the waterproof membrane, the waterproof membrane wiring is reliably disconnected almost simultaneously with the rupture of the waterproof membrane, thereby advantageously enabling the battery monitoring ECU to reliably detect the internal pressure of the battery pack. Furthermore, if the waterproof membrane wiring section is configured to include a connector interposed in the waterproof membrane wiring section and the connector is disconnected when the waterproof membrane ruptures, the connector is easily disconnected when the waterproof membrane ruptures due to an increase in internal case pressure, which makes the wiring section main body more likely to break when the waterproof membrane ruptures, and this is more advantageous for the battery monitoring ECU to reliably detect the internal pressure of the battery pack.Also, if the wiring section main body is configured to include a first wiring section that extends toward the case away from the waterproof membrane and a connector is interposed in the first wiring section and the connector is disconnected when the waterproof membrane ruptures due to an increase in internal case pressure, the connector is easily disconnected when the waterproof membrane ruptures, which makes the wiring section main body more likely to break when the waterproof membrane ruptures, and this is more advantageous for the battery monitoring ECU to reliably detect the internal pressure of the battery pack. Furthermore, if the wiring unit main body comprises a valve body conducting portion provided on the valve body and an opening conducting portion provided on the wall portion for the opening, and the valve body conducting portion and the opening conducting portion are connected when the valve body closes the opening, and the connection between the valve body conducting portion and the opening conducting portion is released when the valve body opens the opening, when the internal pressure of the case rises and the valve body opens the opening, the connection between the valve body conducting portion and the opening conducting portion is easily and reliably released, and the wiring unit main body is easily and reliably broken, which is advantageous for the battery monitoring ECU to reliably detect the internal pressure of the battery pack.Furthermore, if the valve element conducting portion is formed around the entire outer periphery of the valve element, and the opening conducting portions are provided separately from each other in the circumferential direction of the opening wall portion and each connected to the battery monitoring ECU, and include an opening first conducting portion and an opening second conducting portion that are respectively connected to the valve element conducting portion when the valve element closes the opening, then the valve element conducting portion and the opening first conducting portion and the opening second conducting portion are reliably connected when the valve element closes the opening, regardless of the relative rotational position of the valve element and the opening about the axis. Therefore, when assembling the pressure reducing valve, it is not necessary to align the valve element conducting portion with the opening first conducting portion and the opening second conducting portion, and a rotation prevention mechanism to prevent rotation of the valve element is not required, which simplifies the assembly of the pressure reducing valve and is advantageous in reducing the cost of the battery pack. Furthermore, if the wiring portion main body is configured to include a portion formed of a conductive thin film, the wiring portion main body is more likely to break when the waterproof membrane is ruptured, which is advantageous in reliably detecting the internal pressure of the battery pack by the battery monitoring ECU. Furthermore, if the wiring main body is configured to include a portion formed of a conductive thin film, even if there is a slight misalignment between the valve body conductive portion and the opening conductive portion when the valve body is blocking the opening, the wiring main body will not be broken, which is advantageous in preventing the battery monitoring ECU from mistakenly detecting that the wiring main body is broken.

[0007] 1 is a cross-sectional view of a pressure reducing valve and its surrounding area of ​​a battery pack according to a first embodiment. FIG. 2 is a view taken along an arrow A of the waterproof membrane of FIG. 1. FIG. 3 is a flowchart showing the operation of the battery pack according to the first embodiment. FIG. 4 is a cross-sectional view of a pressure reducing valve and its surrounding area of ​​a battery pack according to a second embodiment. FIG. 5 is a view taken along an arrow A of the waterproof membrane of FIG. 4. FIG. 6 is a cross-sectional view of a pressure reducing valve and its surrounding area of ​​a battery pack according to a third embodiment. FIG. 7 is a view taken along an arrow A of the waterproof membrane of FIG. 6. FIG. 8 is a cross-sectional view of a pressure reducing valve and its surrounding area of ​​a battery pack according to a fourth embodiment. FIG. 9 is a view taken along an arrow A of the valve body of FIG. 8. FIG. 10 is a view taken along an arrow A showing a modified example of the valve body conducting portion of the valve body of FIG. 8. FIG. 11 is a view taken along an arrow A showing another modified example of the valve body conducting portion of the valve body of FIG. 8.

[0008] First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A battery pack according to this embodiment is mounted on an electric vehicle using only a motor as a drive source, a hybrid vehicle, or an electric vehicle using a motor as a drive source, such as a plug-in hybrid vehicle that can be externally charged or externally powered, and is used as a battery pack that supplies power to the motor.

[0009] 1, the battery pack 10 includes a battery pack (not shown), an electrical component including a battery monitoring ECU (Electronic Control Unit) 12, a case 16 housing the battery pack and the electrical component, a pressure reducing valve 18A, and a wiring unit main body 20A. The battery pack is made up of multiple battery modules connected together, and each battery module is made up of multiple battery cells connected together. The battery cells are secondary batteries such as lithium-ion batteries, and when a battery cell experiences thermal runaway due to an internal short circuit or other cause, causing the temperature to rise, the battery cell eventually releases high-temperature gas into the case 16.

[0010] The battery monitoring ECU 12 collects various battery information such as the output voltage, output current, temperature, and remaining capacity (SOC: State Of Charge) of the battery pack, and supplies the collected battery information to a host ECU 14 that controls the vehicle via a communication line (e.g., CAN (Controller Area Network) communication). In this embodiment, the battery monitoring ECU 12 has a function of detecting an abnormality in the battery pack 10 by detecting a break in a wiring unit main body 20A, which will be described later. When the host ECU 14 receives detection information of an abnormality in the battery pack 10 from the battery monitoring ECU 12, it notifies the occupant that an abnormality has occurred in the battery pack 10, and, for example, urges the occupant to stop the vehicle if the vehicle is running.

[0011] The pressure reducing valve 18A is provided in the case 16 and opens when the internal pressure of the case 16 increases to suppress the increase in internal pressure. In this embodiment, the pressure reducing valve 18A includes a tubular portion 24, a frame member 26, and a waterproof membrane 28 that form the opening wall portion 22, and the tubular portion 24 and frame member 26 are made of metal or synthetic resin. In this embodiment, the tubular portion 24 has a cylindrical shape, and a flange 2402 at the base of the axial direction of the tubular portion 24 is attached in a liquid-tight and airtight manner to an attachment hole 1602 provided in the top wall or side wall of the case 16. The tip of the tubular portion 24 opposite the base is open to the outside, and in this embodiment, the inside of the tip of the tubular portion 24 forms the opening 30 of the case 16.

[0012] The opening 30 is sealed by a waterproof membrane 28 via the frame member 26. The frame member 26 includes a cylindrical portion 2602 and a ring plate portion 2604 that protrudes radially inward from the tip of the cylindrical portion 2602. As shown in FIGS. 1 and 2 , the waterproof membrane 28 is disk-shaped with an outer diameter substantially equal to the inner diameter of the cylindrical portion 2602, and its outer periphery is liquid-tightly and airtightly attached to the inner surface of the ring plate portion 2604 with an adhesive or the like. The ring plate portion 2604 abuts against the tip surface of the cylindrical portion 2602 via the waterproof membrane 28, and the inner peripheral surface of the cylindrical portion 2602 is liquid-tightly and airtightly attached to the outer peripheral surface of the tip of the tubular portion 24, so that the waterproof membrane 28 seals the opening 30. The waterproof membrane 28 is formed of a membrane that has the function of preventing the passage of liquid water. By providing such a waterproof membrane 28, it is possible to prevent water from entering the case 16 from the outside through the opening 30. The waterproof membrane 28 may be formed of a breathable waterproof membrane that prevents the passage of liquid water but allows water vapor to pass through. Forming the waterproof membrane 28 from a breathable waterproof membrane allows moisture generated inside the case 16 to escape to the outside, preventing condensation inside the case 16, which is advantageous in protecting the battery pack and electrical components. Furthermore, when thermal runaway occurs in the battery pack (battery cells) and the internal pressure of the case 16 increases due to the generation of high-temperature gas, the waterproof membrane 28 bulges upward and ruptures, allowing the high-pressure gas inside the case 16 to be released to the outside, thereby suppressing the increase in internal pressure of the case 16. In other words, the pressure reducing valve 18A opens when the waterproof membrane 28 ruptures.

[0013] The wiring unit main body 20A is disposed from the case 16 to the pressure reducing valve 18A and is disconnected when the pressure reducing valve 18A is opened. In the present embodiment, the wiring unit main body 20A is configured to include a waterproof membrane wiring unit 32, a first lead wire 34, and a second lead wire 36. The waterproof membrane wiring unit 32 is formed on an inner surface 2802 of the waterproof membrane 28 that faces the interior of the case 16. In the present embodiment, as shown in FIG. 2 , the waterproof membrane wiring unit 32 is formed of a conductive thin film that is formed in a strip shape and extends linearly along the diameter direction of the waterproof membrane 28. In other words, the waterproof membrane wiring unit 32 is disposed so as to pass through the center of the waterproof membrane 28, and the waterproof membrane wiring unit 32 is disconnected when the waterproof membrane 28 is ruptured.

[0014] The first lead wire 34 connects one end of the waterproof membrane wiring portion 32 to a signal detection input terminal Ts of the battery monitoring ECU 12, which is grounded via a detection resistor R. The second lead wire 36 connects the other end of the waterproof membrane wiring portion 32 to a voltage output terminal Te, which is provided in the electrical equipment and outputs a predetermined DC voltage E. Therefore, when the waterproof membrane wiring portion 32 is not broken, the DC voltage E is applied to the signal detection input terminal Ts of the battery monitoring ECU 12 via the second lead wire 36, the waterproof membrane wiring portion 32, and the first lead wire 34. On the other hand, when the waterproof membrane wiring portion 32 is broken, the DC voltage E is not applied to the signal detection input terminal Ts of the battery monitoring ECU 12, and the signal detection input terminal Ts is grounded (0 V). Therefore, the battery monitoring ECU 12 can detect a break in the wiring portion main body 20A based on the change in the signal detection input terminal Ts from the predetermined DC voltage E to the grounded state. In other words, the battery monitoring ECU 12 detects a break in the wiring main body 20A, and thereby detects that the waterproof membrane 28 has ruptured when the pressure inside the case rises, in other words, that the pressure reducing valve 18A has opened, thereby detecting the generation of high-pressure gas inside the case 16, and therefore, can detect the occurrence of an abnormality in the battery pack 10.

[0015] Next, the operation and effect of the system will be described with reference to the flowchart of FIG. 3 . First, some abnormality occurs in the battery pack 10, causing thermal runaway in the battery pack (step S10). Over time, high-temperature gas is generated from the battery pack (step S12), causing the internal case pressure to rise (step S14). Eventually, the internal case pressure opens the pressure reducing valve 18A (in this embodiment, the waterproof membrane 28 is ruptured) (step S16). This causes the wiring main body 20A to break (step S18), and the battery monitoring ECU 12 detects this (step S20). The battery monitoring ECU 12 then provides detection information about the abnormality in the battery pack 10 to the host ECU 14 (step S22). The host ECU 14 then notifies the occupant of the abnormality using a display device or the like provided on the instrument panel inside the vehicle (step S24). The abnormality notification may be made by sounding a warning sound from a speaker, or may be made by combining a display device and a speaker.

[0016] According to this embodiment, a wiring unit main body 20A that is disconnected when the pressure reducing valve 18A is opened is provided from the case 16 to the pressure reducing valve 18A, and the battery monitoring ECU 12 connected to the wiring unit main body 20A detects the disconnection of the wiring unit main body 20A to detect the occurrence of an abnormality in the battery pack 10. This eliminates the need for a pressure sensor that was conventionally required to detect the internal case pressure, thereby reducing manufacturing costs and providing the advantage that the battery monitoring ECU 12 can reliably detect the internal pressure of the battery pack 10 by detecting the disconnection of the wiring unit main body 20A in the same way as when a pressure sensor is provided.

[0017] Furthermore, in the present embodiment, the pressure reducing valve 18A is opened by rupturing the waterproof membrane 28 that seals the opening 30 provided in the case 16, and the rupture of the waterproof membrane 28 disconnects the waterproof membrane wiring portion 32 formed on the inner surface 2802 of the waterproof membrane 28. Therefore, the waterproof membrane wiring portion 32 is reliably disconnected almost simultaneously with the rupture of the waterproof membrane 28, which is advantageous for reliably detecting the internal pressure of the battery pack 10 by the battery monitoring ECU 12. Note that although the waterproof membrane wiring portion 32 may be provided on the outer surface or inside of the waterproof membrane 28, providing it on the inner surface 2802 of the waterproof membrane 28 facing the interior of the case 16 as in the present embodiment allows for easy connection to the first lead wire 34 and the second lead wire 36, which is advantageous for reducing costs.

[0018] In addition, in this embodiment, the wiring section main body 20A is configured to include a portion formed of a conductive thin film, and more specifically, the waterproof membrane wiring section 32 is formed of a conductive thin film, so that the wiring section main body 20A is likely to break when the waterproof membrane 28 is ruptured, which is advantageous for the battery monitoring ECU 12 to reliably detect the internal pressure of the battery pack 10.

[0019] Second Embodiment Next, a second embodiment will be described with reference to FIGS. 4 and 5 . In the following description, parts and components similar to those of the first embodiment are denoted by the same reference numerals, and their description will be omitted or simplified. The following description will focus on the differences. The second embodiment is a modification of the first embodiment. In a pressure reducing valve 18B of the second embodiment, the waterproof membrane wiring 32 constituting the wiring main body 20B is arranged to pass through the center of the waterproof membrane 28, as in the first embodiment. As shown in FIGS. 4 and 5 , the second embodiment differs from the first embodiment in that a connector 42 is provided in the waterproof membrane wiring 32. That is, the waterproof membrane wiring 32 includes a first waterproof membrane wiring 38, a second waterproof membrane wiring 40, and a connector 42 connecting the first and second waterproof membrane wiring 38, 40. The base end of the first waterproof membrane wiring portion 38 is connected to the first lead wire 34, and the base end of the second waterproof membrane wiring portion 40 is connected to the second lead wire 36. The connector 42 is composed of a first connector member 4202 connected to the tip of the first waterproof membrane wiring portion 38 and a second connector member 4204 connected to the tip of the second waterproof membrane wiring portion 40 and removably insertable into the first connector member 4202, and the first connector member 4202 and the second connector member 4204 are arranged in a connected state. When the internal pressure of the case increases, the waterproof membrane 28 bulges upward and ruptures, thereby releasing the connection state of the connector 42. In other words, the connection between the first connector member 4202 and the second connector member 4204 is released, thereby breaking the wiring portion main body 20B.

[0020] According to the second embodiment, not only can the same effects as those of the first embodiment be achieved, but also, when the waterproof membrane 28 is ruptured due to an increase in the internal pressure of the case, the connector 42 is easily disconnected, so that the wiring main body 20B is more likely to break when the waterproof membrane 28 is ruptured, which is more advantageous in ensuring that the internal pressure of the battery pack 10 is detected reliably by the battery monitoring ECU 12.

[0021] Third Embodiment Next, a third embodiment will be described with reference to FIGS. 6 and 7 . The third embodiment is a modification of the second embodiment. As shown in FIG. 7 , in a pressure reducing valve 18C according to the third embodiment, the waterproof membrane wiring 32 constituting the wiring main body 20B is formed of a conductive thin film and is configured with a wiring portion 44 extending from the edge of the waterproof membrane 28 to the center. As shown in FIG. 6 , the wiring main body 20B includes a first wiring portion 46 extending from the end of the wiring portion 44 located in the center toward the case 16, away from the waterproof membrane 28. The first wiring portion 46 is connected to the voltage output terminal Te, similar to the second lead wire 36 of the first and second embodiments. A connector 48 is interposed in the first wiring portion 46, and therefore the wiring main body 20C includes the connector 48. The connector 48 is composed of a first connector member 4802 connected to an end of the wiring portion 44, and a second connector member 4804 that is detachably insertable into the first connector member 4802 and connected to an end of the first wiring unit 46, and the first connector member 4802 and the second connector member 4804 are arranged in a connected state. When the internal pressure of the case increases, the waterproof membrane 28 bulges upward and breaks, releasing the connection state of the connector 48. In other words, the connection between the first connector member 4802 and the second connector member 4804 is released, thereby breaking the wiring unit main body 20C.

[0022] According to the third embodiment, it goes without saying that the same effects as those of the first embodiment are achieved, and like the second embodiment, the connector 48 is easily disconnected when the waterproof membrane 28 is ruptured due to an increase in the internal pressure of the case, so that the wiring unit main body 20C is more likely to break when the waterproof membrane 28 is ruptured, which is more advantageous in ensuring that the internal pressure of the battery pack 10 is detected reliably by the battery monitoring ECU 12.

[0023] (Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIGS. 8 and 9 . In the fourth embodiment, the structure of a pressure reducing valve 18D differs from the first to third embodiments. As shown in FIG. 8 , the pressure reducing valve 18D includes a tubular portion 50 constituting the opening wall portion 22, a cap member 52, a valve body 54, and a biasing member 56. The tubular portion 50 has a cylindrical shape, and a flange 5002 at the axial base of the tubular portion 50 is attached in a liquid-tight and airtight manner to a mounting hole 1602 provided in the top wall or side wall of the case 16. The tip of the tubular portion 50 opposite the base is open to the outside, and in this embodiment, the inside of the tip of the tubular portion 50 forms the opening 30 of the case 16. The cap member 52 includes a cylindrical wall portion 5202 and an upper wall 5204 that closes the upper end of the cylindrical wall portion 5202. A plurality of windows 5206 that allow high-temperature gas to escape are formed at intervals in the circumferential direction of the cylindrical wall portion 5202. The inner peripheral surface of an annular plate portion 5208 that protrudes radially inward from the lower end of the cylindrical wall portion 5202 is attached liquid-tight and airtight to the outer peripheral surface of the tube portion 50.

[0024] Valve body 54 is a disk-shaped member large enough to cover the upper end of cylindrical portion 50 and close opening 30, and is constantly biased in the direction of closing opening 30, and when the internal pressure of case 16 rises, it moves above opening 30 to open opening 30. Biasing member 56 is formed by a coil spring provided between upper wall 5204 and valve body 54, and constantly biases valve body 54 in the direction of closing opening 30.

[0025] The wiring unit main body 20D includes a valve element conducting portion 58, an opening conducting portion 60, a first lead wire 62, and a second lead wire 64. As shown in Fig. 9, the valve element conducting portion 58 is formed of a conductive thin film provided on the inner surface 5402 of the valve element 54 that faces the inside of the case 16, and is formed in a band shape extending along the diameter of the valve element 54 so as to pass through the center of the valve element 54. As shown in Fig. 8, the opening conducting portion 60 is provided separately at positions on the upper end surface of the tubular portion 50 that are 180 degrees out of phase with each other in the circumferential direction of the tubular portion 50, and includes a first opening conducting portion 6002 and a second opening conducting portion 6004 connected to the battery monitoring ECU 12, each of which is formed of a conductive thin film. In detail, the opening first conductive portion 6002 is connected to the signal detection input terminal Ts of the battery monitoring ECU 12 via the first lead wire 62, and the opening second conductive portion 6004 is connected to the voltage output terminal Te via the second lead wire 64.

[0026] The pressure reducing valve 18D is assembled by aligning the valve element conducting portion 58 with the opening first conducting portion 6002 and the opening second conducting portion 6004 so that the valve element conducting portion 58 is connected to the opening first conducting portion 6002 and the opening second conducting portion 6004 when the valve element 54 closes the opening 30, and an anti-rotation mechanism (not shown) prevents rotation of the valve element 54. The anti-rotation mechanism may have any of various conventionally known structures, such as a pin protruding from the outer periphery of the valve element 54 and a groove provided on the inner surface of the cylindrical wall portion 5202 of the cap member 52 that supports the pin so that it can move up and down.

[0027] As shown in Figure 8, when the valve body 54 is blocking the opening 30, the valve body conductive portion 58 and the opening conductive portion 60 are connected, thereby bringing the wiring unit main body 20D into a conductive state (non-open state), and a DC voltage E is applied to the signal detection input terminal Ts of the battery monitoring ECU 12 via the second lead wire 64, the opening second conductive portion 6004, the valve body conductive portion 58, the opening first conductive portion 6002, and the first lead wire 62.

[0028] On the other hand, when the valve element 54 moves upward and opens the opening 30 in response to an increase in the internal case pressure, the high-pressure gas inside the case 16 is released to the outside of the case 16 through the window 5206, thereby suppressing an increase in the internal pressure of the case 16. That is, the pressure reducing valve 18D is opened by the movement of the valve element 54. Then, when the valve element 54 moves upward in response to an increase in the internal case pressure and opens the opening 30, the connection between the valve element conducting portion 58 and the opening first conducting portion 6002 and the opening second conducting portion 6004 is released, resulting in an open circuit in the wiring unit main body 20D, and the signal detection input terminal Ts of the battery monitoring ECU 12 not being applied with the DC voltage E and being grounded.

[0029] Therefore, the battery monitoring ECU 12 can detect that a break has occurred in the wiring main body 20D based on the change in the signal detection input terminal Ts from a predetermined DC voltage E to a grounded state. That is, by detecting a break in the wiring main body 20D, the battery monitoring ECU 12 can detect that the waterproof membrane 28 inside the case 16 has ruptured when the internal pressure of the case rises, in other words, that the pressure reducing valve 18D has opened, and can detect the generation of high-pressure gas inside the case 16 and the occurrence of an abnormality in the battery pack 10.

[0030] Even when the internal pressure of the case has not increased, if a load is applied to the valve body 54 due to, for example, large vibrations of the vehicle body while driving, the valve body 54 may open and close against the biasing force of the biasing member 56, causing intermittent disconnections in the wiring unit main body 20D, which may cause the battery monitoring ECU 12 to erroneously detect an abnormality in the battery pack 10. In this case, for example, the battery monitoring ECU 12 may measure the disconnection time Td during which the wiring unit main body 20D is disconnected, and may determine that "no disconnection has occurred" if the disconnection time Td<predetermined time T0, and may determine that "a disconnection has occurred" if the disconnection time Td≧predetermined time T0, thereby preventing erroneous detection by the battery monitoring ECU 12.

[0031] According to the fourth embodiment, not only can the same effects as those of the first embodiment be achieved, but also, when the valve element 54 opens the opening 30 due to an increase in internal case pressure, the connection between the valve element conducting portion 58 and the opening conducting portion 60 is easily and reliably released, thereby easily and reliably disconnecting the wiring portion main body 20D, which is advantageous for reliably detecting the internal pressure of the battery pack 10 by the battery monitoring ECU 12. Furthermore, since the wiring portion main body 20D is configured to include a portion formed of a conductive thin film, and more specifically, the valve element conducting portion 58 and the opening conducting portion 60 are formed of a conductive thin film, when the valve element 54 closes the opening 30, the valve element conducting portion 58 and the opening conducting portion 60 are in surface contact with each other, thereby reliably establishing electrical continuity between them. Therefore, even if there is a slight misalignment between the valve body conducting portion 58 and the opening conducting portion 60 when the valve body 54 is blocking the opening 30, the wiring unit main body 20D will not be broken, which is advantageous in preventing the battery monitoring ECU 12 from mistakenly detecting that the wiring unit main body 20D is broken.

[0032] Next, modifications of the valve element conducting portion 58 of the fourth embodiment will be described with reference to Figures 10 and 11. The valve element conducting portion 58 shown in Figure 10 is formed around the entire outer periphery of the inner surface 5402 of the valve element 54, and more specifically, is formed in an annular shape around the entire outer periphery of the valve element 54. The valve element conducting portion 58 shown in Figure 11 is formed around the entire outer periphery of the inner surface 5402 of the valve element 54, and more specifically, is formed over the entire inner surface 5402 of the valve element 54. Note that, similar to Figure 9, the opening conducting portion 60 is provided on the upper end surface of the tubular portion 50 at separate locations that are 180 degrees apart in the circumferential direction of the tubular portion 50, and includes a first opening conducting portion 6002 and a second opening conducting portion 6004 that are connected to the battery monitoring ECU 12.

[0033] Needless to say, such modifications can achieve the same effects as those of the fourth embodiment, and according to each modification, when the valve element 54 closes the opening 30, the valve element conducting portion 58 is reliably connected to the first opening conducting portion 6002 and the second opening conducting portion 6004, regardless of the relative rotational positions about the axis of the valve element 54 and the opening 30. Therefore, when assembling the pressure reducing valve 18D, it is not necessary to align the rotational positions about the axis of the valve element 54 and the opening 30, in other words, it is not necessary to align the valve element conducting portion 58 with the first opening conducting portion 6002 and the second opening conducting portion 6004, and a rotation prevention mechanism for preventing rotation of the valve element 54 is also not required. This simplifies the assembly of the pressure reducing valve 18D, which is advantageous for reducing the cost of the battery pack 10.

[0034] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0035] This application is based on a Japanese patent application (Patent Application No. 2024-1756) filed on January 10, 2024, the contents of which are incorporated herein by reference.

[0036] REFERENCE SIGNS LIST 10 Battery pack 12 Battery monitoring ECU 14 Host ECU 16 Case 1602 Mounting hole 18A, 18B, 18C, 18D Pressure reducing valve 20A, 20B, 20C, 20D Wiring section main body 22 Opening wall 24 Cylindrical section 2402 Flange 26 Frame member 2602 Cylindrical section 2604 Ring plate section 28 Waterproof membrane 2802 Inner surface 30 Opening 32 Waterproof membrane wiring section 34 First lead wire 36 Second lead wire 38 First waterproof membrane wiring section 40 Second waterproof membrane wiring section 42 Connector 4202 First connector member 4204 Second connector member 44 Wiring section 46 First wiring section 48 Connector 4802 First connector member 4804 Second connector member 50 Cylindrical section 5002 Flange 52 Cap member 5202 Cylindrical wall portion 5204 Upper wall 5206 Window portion 5208 Annular plate portion 54 Valve body 5402 Inner surface 56 Pressurizing member 58 Valve body conducting portion 60 Opening conducting portion 6002 Opening first conducting portion 6004 Opening second conducting portion 62 First lead wire 64 Second lead wire

Claims

1. A battery pack comprising: a case that houses a battery pack; and a pressure reducing valve that is provided in the case and opens when an internal pressure of the case increases to suppress the increase in the internal pressure, a wiring unit main body that is provided from the case to the pressure reducing valve and that is disconnected when the pressure reducing valve is opened; a battery monitoring ECU that detects an abnormality in the battery pack by detecting a break in the wiring main body; Equipped with the pressure reducing valve is configured to include an opening provided in the case and a waterproof membrane that seals the opening, The pressure reducing valve is opened by rupturing the waterproof membrane, the wiring body is configured to include a waterproof membrane wiring part that is formed in the waterproof membrane and that is broken when the waterproof membrane is broken, The waterproof membrane wiring portion is provided so as to pass through a center portion of the waterproof membrane, the waterproof membrane wiring section is configured to include a connector interposed in the waterproof membrane wiring section, When the waterproof membrane is broken, the connector is released from connection. A battery pack characterized by:

2. A battery pack comprising: a case that houses a battery pack; and a pressure reducing valve that is provided in the case and opens when an internal pressure of the case increases to suppress the increase in the internal pressure, a wiring unit main body that is provided from the case to the pressure reducing valve and that is disconnected when the pressure reducing valve is opened; a battery monitoring ECU that detects an abnormality in the battery pack by detecting a break in the wiring main body; Equipped with the pressure reducing valve is configured to include an opening provided in the case and a waterproof membrane that seals the opening, The pressure reducing valve is opened by rupturing the waterproof membrane, the wiring body is configured to include a waterproof membrane wiring part that is formed in the waterproof membrane and that is broken when the waterproof membrane is broken, The waterproof membrane wiring portion is composed of a wiring portion extending from an edge portion of the waterproof membrane to a center portion thereof, the wiring body includes a first wiring portion extending from an end of the wiring portion located in the central portion toward the case, away from the waterproof membrane; a connector is interposed in the first wiring portion, When the waterproof membrane is broken, the connector is released from connection. A battery pack characterized by:

3. the pressure reducing valve is configured to include an opening wall portion that is provided in the case and forms an opening, and a valve body that is constantly biased in a direction to close the opening and that separates from the opening wall portion when the internal pressure of the case increases to open the opening, The wiring body includes a valve body conducting portion provided on the valve body, an opening conduction portion provided in the opening wall portion and connected to the battery monitoring ECU, the valve body conducting portion and the opening conducting portion are connected in a state where the valve body closes the opening, the valve body conducting portion and the opening conducting portion are disconnected in a state where the valve body opens the opening.

2. The battery pack according to claim 1.

4. the pressure reducing valve is configured to include an opening wall portion that is provided in the case and forms an opening, and a valve body that is constantly biased in a direction to close the opening and that separates from the opening wall portion when the internal pressure of the case increases to open the opening, The wiring body includes a valve body conducting portion provided on the valve body, an opening conduction portion provided in the opening wall portion and connected to the battery monitoring ECU, the valve body conducting portion and the opening conducting portion are connected in a state where the valve body closes the opening, the valve body conducting portion and the opening conducting portion are disconnected in a state where the valve body opens the opening.

3. The battery pack according to claim 2.

5. the valve body conducting portion is formed around the entire outer periphery of the valve body, the opening conduction portions are provided separately from each other in the circumferential direction of the opening wall portion, and are each connected to the battery monitoring ECU, and are configured to include an opening first conduction portion and an opening second conduction portion that are each connected to the valve body conduction portion when the valve body closes the opening.

4. The battery pack according to claim 3.

6. the valve body conducting portion is formed around the entire outer periphery of the valve body, the opening conduction portions are provided separately from each other in the circumferential direction of the opening wall portion, and are each connected to the battery monitoring ECU, and are configured to include an opening first conduction portion and an opening second conduction portion that are each connected to the valve body conduction portion when the valve body closes the opening.

5. The battery pack according to claim 4.

7. At least a part of the wiring body is configured to include a portion formed of a conductive thin film.

7. The battery pack according to claim 1, wherein the battery pack comprises: a first insulating layer;