Battery Module

Abstract

This battery module (100) is provided with: a battery laminate body which comprises, laminated in a first direction, multiple batteries provided respective valves that eject gas; a discharge path through which the gas emitted from the aforementioned valves is discharged in a second direction which intersects the first direction; a light emitting unit (50) which is provided on one end of the battery laminate body in the first direction and which emits light towards the discharge path; and a light receiving unit (60) which is provided on the other end of the battery laminate body in the first direction and which receives light emitted from the light emission unit (50).

Description

[Technical field]

[0001] The present invention relates to a battery module. [Background technology]

[0002] Battery modules in which multiple batteries are electrically connected are known as power sources that require a high output voltage, such as for vehicles. In general, each battery constituting a battery module is provided with a valve that opens in response to an increase in internal pressure. When gas is generated by a chemical reaction inside the battery, and the internal pressure of the battery increases as a result, high-temperature, high-pressure gas is ejected from the valve. Regarding a battery module including such batteries, Patent Document 1 discloses a battery module including a battery stack in which multiple batteries are stacked, and an exhaust duct fixed to one surface of the battery stack so as to be connected to the valve of each battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 161655 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, a temperature sensor installed to detect the temperature of a battery in a battery module cannot sound an alarm even if gas is generated in the battery unless heat is transferred to the temperature sensor. The temperature sensor does not measure the temperature of the gas, and even if gas is generated, the temperature sensor cannot detect the generation of gas unless the temperature of the battery itself rises.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for improving the safety of a battery module. [Means for solving the problem]

[0006] A battery module according to one embodiment of the present invention is characterized in that it comprises a battery stack in a first direction in which a number of batteries, each having a valve portion for ejecting gas, are stacked together; an exhaust path for exhausting gas ejected from the valve portion in a second direction intersecting the first direction; a light emitting portion provided at one end of the battery stack in the first direction for emitting light into the exhaust path; and a light receiving portion provided at the other end of the battery stack in the first direction for receiving light emitted from the light emitting portion. Effect of the Invention

[0007] According to the present invention, the safety of the battery module can be improved. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an external appearance of a battery module according to an embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of a portion of the battery module. [Figure 3A] FIG. 2 is a schematic diagram showing a case where batteries are connected in parallel. [Figure 3B] FIG. 2 is a schematic diagram showing a case where batteries are connected in series. [Figure 4] FIG. 2 is a cross-sectional side view of an area including a duct plate and a cover plate of a battery module. [Diagram 5] FIG. 2 is a schematic diagram for explaining the arrangement of a light emitting portion and a light receiving portion. [Figure 6A] FIG. 2 is a cross-sectional view illustrating a configuration of a light emitting portion. [Figure 6B] FIG. 2 is a schematic cross-sectional view showing a configuration of a light receiving section. [Figure 7A] 13 is a schematic cross-sectional view showing a configuration of a light exit portion according to a modified example. FIG. [Figure 7B] 13 is a schematic cross-sectional view showing a configuration of a light receiving section according to a modified example. FIG. [Figure 8] 13 is a schematic cross-sectional view showing a configuration of a light exit portion according to another modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation, and are not to be interpreted as being limiting unless otherwise specified. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are intended to distinguish one configuration from another. In addition, some of the members that are not important in explaining the embodiment in each drawing are omitted.

[0010] (Embodiment) Fig. 1 is a perspective view showing the appearance of a battery module 100 according to an embodiment, and Fig. 2 is an exploded perspective view of a portion of the battery module 100. The battery module 100 comprises a battery stack 2, a rectangular parallelepiped housing 10, a duct plate 30, a cover plate 40, a light emitting unit 50, and a light receiving unit 60.

[0011] The housing 10 is composed of end plates 11 located at both ends of the stacking direction of the batteries 20 in the battery stack 2, side plates 12 that sandwich the end plates 11 and cover the sides of the battery stack 2, and a base plate 13 that covers the bottom of the battery stack 2. The battery stack 2 is stored inside the housing 10 and is covered by a duct plate 30 and a cover plate 40. In each figure, the stacking direction of the batteries is defined as the X direction, the direction that intersects the X direction and corresponds to the side of the batteries is defined as the Y direction, and the direction that intersects the X and Y directions is defined as the Z direction. The stacking direction of the batteries (X direction) corresponds to the first direction in the claims, and the Y direction that intersects the X direction corresponds to the second direction in the claims.

[0012] The battery stack 2 is constructed by stacking a plurality of batteries 20 along the X direction. A spacer formed in a sheet or plate shape of a resin material or the like may be disposed between each battery to provide electrical insulation. Each battery 20 is, for example, a rechargeable secondary battery such as a lithium ion battery, a nickel-hydrogen battery, or a nickel-cadmium battery. Each battery 20 is a so-called prismatic battery, and has an exterior can 21 in the shape of a flattened rectangular parallelepiped. A substantially rectangular opening (not shown) is provided on one side of the exterior can 21, and an electrode body, an electrolyte, and the like are accommodated in the exterior can 21 through this opening. A sealing plate 21a is provided at the opening of the exterior can 21 to cover the opening.

[0013] A positive output terminal 22 is disposed on the sealing plate 21a near one end in the longitudinal direction, and a negative output terminal 22 is disposed on the other end. The pair of output terminals 22 are electrically connected to the positive and negative plates constituting the electrode body, respectively. Hereinafter, the positive output terminal 22 will be referred to as the positive terminal 22a, and the negative output terminal 22 will be referred to as the negative terminal 22b, as appropriate. In addition, when it is not necessary to distinguish the polarity of the output terminals 22, the positive terminal 22a and the negative terminal 22b will be collectively referred to as the output terminals 22.

[0014] Each output terminal 22 is inserted into a through hole (not shown) formed in the sealing plate 21a. An insulating seal member (not shown) is interposed between each output terminal 22 and each through hole. For convenience in the following description, the sealing plate 21a is referred to as the upper surface of the battery 20, and the bottom surface of the exterior can 21 facing the sealing plate 21a is referred to as the lower surface of the battery 20.

[0015] The battery 20 also has two main surfaces connecting the upper and lower surfaces. These main surfaces are the surfaces with the largest area among the six surfaces of the battery 20. The main surfaces are the long side surfaces connected to the long sides of the upper and lower surfaces. The two remaining surfaces excluding the upper and lower surfaces and the two main surfaces are the side surfaces of the battery 20. These side surfaces are a pair of short side surfaces connected to the short sides of the upper and lower surfaces. These directions and positions are defined for convenience. Therefore, for example, the portion defined as the upper surface in the present invention does not necessarily mean that it is located above the portion defined as the lower surface.

[0016] The sealing plate 21a is provided with a valve portion 24 between the pair of output terminals 22. The valve portion 24 is also called a safety valve, and is a mechanism for each battery 20 to eject gas inside the battery. The valve portion 24 is configured to open when the internal pressure of the exterior can 21 rises to a predetermined value or higher, and to release the internal gas. The valve portion 24 is configured, for example, with a thin-walled portion that is thinner than the other portions and is provided in a part of the sealing plate 21a, and a linear groove formed on the surface of the thin-walled portion. In this configuration, when the internal pressure of the exterior can 21 rises, the thin-walled portion tears starting from the groove, and the valve is opened. The valve portion 24 of each battery 20 is connected to an exhaust path 33, which will be described later, and the gas inside the battery is exhausted from the valve portion 24 to the exhaust path 33.

[0017] The multiple batteries 20 are stacked at a predetermined interval so that the main surfaces of adjacent batteries 20 face each other. Note that "stacking" means arranging multiple members in any one direction. Therefore, stacking the batteries 20 also includes arranging the multiple batteries 20 horizontally. In this embodiment, the batteries 20 are stacked horizontally, and the X direction, which is the stacking direction of the batteries 20, is the horizontal extension direction. The Y direction is horizontal and perpendicular to the X direction, and the Z direction perpendicular to the X and Y directions is vertical.

[0018] The batteries 20 are arranged so that the output terminals 22 face in the same direction. In this embodiment, the batteries 20 are arranged so that the output terminals 22 face vertically upward. Fig. 3A is a schematic diagram showing the batteries 20 connected in parallel, and Fig. 3B is a schematic diagram showing the batteries 20 connected in series. Figs. 3A and 3B correspond to views of the top surfaces of the stacked batteries 20.

[0019] As shown in Fig. 3A, when the batteries 20 are electrically connected in parallel, the batteries 20 are stacked so that the positive terminal 22a of one of the adjacent batteries 20 is adjacent to the positive terminal 22a of the other battery 20, and the positive electrodes or negative electrodes are connected by a bus bar 28. In Fig. 3A, three blocks are provided, each block having four batteries 20, which are a part of the 12 batteries 20, electrically connected in parallel, and each block is connected in series. Note that when the batteries 20 are connected in parallel, there are cases in which a voltage abnormality occurs in one battery 20 but the voltage abnormality is not detected in the entire block.

[0020] As shown in Fig. 3B, when the batteries 20 are electrically connected in series, the batteries 20 are stacked so that the positive terminal 22a of one of the adjacent batteries 20 and the negative terminal 22b of the other battery 20 are adjacent to each other, and the positive and negative electrodes are connected by a bus bar 28. In Fig. 3B, all 12 batteries 20 are connected in series.

[0021] The duct plate 30 is placed on the top surface of the battery stack 2. The duct plate 30 is a resin plate-like member that covers the top surface of the battery stack 2, i.e., the surface where the valve portions 24 of each battery 20 are located, and is fixed to the battery stack 2 by, for example, the side plate 12.

[0022] The duct plate 30 has a base plate 31 extending along the upper surface of the battery stack 2, and has multiple openings 32 exposing the valve portions 24 of each battery 20 at positions on the base plate 31 corresponding to the valve portions 24 of each battery 20. The duct plate 30 also has exhaust paths 33 that temporarily store gas ejected from each battery 20. The exhaust paths 33 extend in the stacking direction X of the batteries 20 and are connected to the valve portions 24 of each battery 20. Each valve portion 24 is in communication with the exhaust paths 33 via the openings 32.

[0023] The discharge path 33 is defined by a shielding portion 41 of the cover plate 40 that covers the upper sides of the multiple openings 32, and a pair of wall portions 34 that surround the sides of each opening 32. The shielding portion 41 and the pair of wall portions 34 are each elongated in the X direction. The pair of wall portions 34 are arranged in the Y direction with the multiple openings 32 or the multiple valve portions 24 between them, and each wall surface faces the Y direction. The pair of wall portions 34 are formed so as to protrude from the base plate 31 toward the cover plate 40. The shielding portion 41 forms the top surface of the discharge path 33.

[0024] The color of each wall surface of the shielding portion 41 of the cover plate 40, the pair of wall portions 34 surrounding the sides of each opening 32, and the base plate 31, which face the discharge path 33 and partition the discharge path 33, is a color such as black that suppresses light reflection. The color of the wall surface may be the base color of the material constituting each part, or may be colored by plating or painting.

[0025] The duct plate 30 also has openings 36 at positions corresponding to the output terminals 22 of each battery 20, through which the output terminals 22 are exposed. A bus bar 28 is placed in each opening 36. The multiple bus bars 28 are supported by the duct plate 30. Therefore, the duct plate 30 also functions as a so-called bus bar plate. The output terminals 22 of adjacent batteries 20 are electrically connected to each other by the bus bars 28 placed in each opening 36.

[0026] The cover plate 40 is a plate-like member that covers the upper part of the duct plate 30, and is placed on the upper surface of the duct plate 30. The cover plate 40 is made of, for example, insulating resin. The cover plate 40 has a shielding portion 41 that covers the exhaust path 33 and the wall portion 34 of the duct plate 30, and a terminal covering portion 42 that extends from the shielding portion 41 to both ends of the duct plate 30 in the Y direction and covers the output terminals 22 of the battery 20.

[0027] The cover plate 40 of this embodiment is a so-called top cover that constitutes part of the outer casing of the battery module 100, specifically, the upper surface of the battery module 100. The cover plate 40 prevents condensed water, dust, and the like from coming into contact with the output terminals 22, the valve portion 24, the bus bars 28, and the like of the battery 20.

[0028] The cover plate 40 has both ends in the Y direction fixed to the duct plate 30. The duct plate 30 has a plurality of engagement claws 37 spaced apart in the X direction at both ends in the Y direction. The cover plate 40 has engagement holes 47 at positions overlapping with the engagement claws 37 when viewed from the Z direction, and the engagement claws 37 are inserted into the engagement holes 47 and engaged with each other, thereby fixing the cover plate 40 to the duct plate 30. In this embodiment, the cover plate 40 is fixed to the duct plate 30 by a so-called snap fit, but may be fixed to the duct plate 30 by using a fastener such as a screw.

[0029] Fig. 4 is a cross-sectional side view of a region including the duct plate 30 and the cover plate 40 of the battery module 100. Note that the internal structure of the battery 20 is not shown in Fig. 4. The battery module 100 includes a flow path section 70. The flow path section 70 is a flow path that causes gas in the exhaust path 33 to leak to the outside of the battery module 100. The exhaust path 33 is connected to the flow path section 70 that causes gas in the exhaust path 33 to leak to the outside, thereby exhausting gas in the Y direction.

[0030] The flow path portion 70 is defined by the duct plate 30 and the cover plate 40, and extends in the Y direction (i.e., the second direction in the claims) from the discharge path 33. In this embodiment, the flow path portions 70 are arranged on both sides in the Y direction of the discharge path 33. Each flow path portion 70 communicates with the discharge path 33 through a gap 71 between the wall portion 34 of the duct plate 30 and the shielding portion 41 of the cover plate 40, and is connected to the outside of the battery module 100 by a flow path outlet 72 arranged at the end in the Y direction.

[0031] The gaps 71 are formed to extend to the batteries 20 at both ends of the battery stack 2 in the X direction. The flow path outlets 72 are formed as long openings extending in the X direction corresponding to the gaps 71. Thus, the flow path section 70 is a planar flow path extending in the X and Y directions. The gaps 71 and the flow path outlets 72 may be partitioned to form a plurality of gaps and openings in the X direction.

[0032] Fig. 5 is a schematic diagram for explaining the arrangement of the light emitting section 50 and the light receiving section 60. Fig. 6A is a schematic cross-sectional view showing the configuration of the light emitting section 50, and Fig. 6B is a schematic cross-sectional view showing the configuration of the light receiving section 60. The light emitting section 50 is provided at one end side in the X direction of the discharge path 33 of the battery module 100. The light receiving section 60 faces the light emitting section 50 and is provided at the other end side in the X direction of the discharge path 33.

[0033] The light emitting section 50 is configured by providing a light source 52, an emitting lens section 53, and a transparent window 54 in a housing 51. The housing 51 has an opening 51a facing the exhaust path 33. A transparent window 54 is fitted into the opening 51a. The transparent window 54 transmits the light flux emitted from the light source 52 to the exhaust path 33 and prevents gas discharged from the battery 20 to the exhaust path 33 from flowing into the housing 51.

[0034] The light source 52 is, for example, a semiconductor laser, and emits light toward the discharge path 33. The emission lens unit 53 can adjust the light beam emitted from the light source 52 to an arbitrary light beam. That is, the light beam emitted from the light source 52 is adjusted to a parallel light beam as an infinite system, or to a light beam having an arbitrary diffusion angle as a finite system. The lens portion of the emission lens unit 53 can use known technologies and optical components developed in various technical fields related to collimation of emitted light.

[0035] The light receiving section 60 is configured by providing a light receiving element 62, a light receiving lens section 63, and a transparent window 64 within a housing 61. The housing 61 has an opening 61a facing the exhaust path 33. A transparent window 64 is fitted into the opening 61a. The transparent window 64 transmits the light flux from the exhaust path 33 into the housing 61 and prevents gas discharged from the battery 20 to the exhaust path 33 from flowing into the housing 61.

[0036] The light receiving element 62 is, for example, a photodiode, and detects the light flux transmitted from the discharge path 33 into the housing 61. The light receiving lens unit 63 adjusts the light flux transmitted into the housing 61 to an arbitrary light flux and transmits it to the light receiving element 62. The light receiving lens unit 63, for example, collects the light flux transmitted into the housing 61 and transmits it to the light receiving element 62. Note that the lens portion of the light receiving lens unit 63 can use known technologies and optical components developed in various technical fields related to the collection of light fluxes, etc.

[0037] Next, the operation of the battery module 100 will be described based on the discharge and detection of gas emitted from the battery 20. At least a part of the gas emitted from the battery 20 is flammable gas. The gas emitted from the battery 20 also contains fine particles such as broken pieces of the battery structure. If high-temperature flammable gas and high-temperature fine particles are discharged to the outside of the battery module 100, the scale of fire outside the battery module 100 may increase. In contrast, in this embodiment, the gas emitted from the valve portion 24 is once discharged to the outside of the battery module 100 via the discharge path 33 and the flow path portion 70, so that the temperature of the gas and fine particles can be reduced before they are discharged to the outside of the battery module 100.

[0038] The light emitted from the light emitting unit 50 passes through the exhaust path 33 and is received by the light receiving unit 60, and the level of received light is approximately constant unless gas is being emitted into the exhaust path 33. When gas is emitted from the battery 20 into the exhaust path 33, the light emitted from the light emitting unit 50 hits the gas and becomes dimmed, and the level of received light at the light receiving unit 60 drops, making it possible to detect the gas emission. When gas emission is detected, the battery module 100 outputs an alarm signal, and measures such as limiting and stopping the output of the battery module 100 are taken based on the alarm signal, thereby improving the safety of the battery module.

[0039] By providing the light-emitting unit 50 at one end in the X-direction, which is the stacking direction of the battery stack 2, and the light-receiving unit 60 at the other end, it is possible to detect gas emissions for all of the batteries 20 included in the battery stack 2.

[0040] When some of the multiple batteries 20 stacked in the battery module 100 are electrically connected in parallel, there are cases where a voltage abnormality occurs in one battery 20 included in a parallel-connected block, but the voltage abnormality is not detected in the entire block. Even in such a situation, if gas is released from a battery 20 with a voltage abnormality, the light emitting unit 50 and the light receiving unit 60 can detect the gas release and detect the abnormal state of the battery 20.

[0041] By providing the transparent window 54 in the light emitting unit 50, it is possible to prevent the gas ejected into the exhaust path 33 from flowing into the housing 51 and adhering to the light source 52. Moreover, by providing the transparent window 64 in the light receiving unit 60, it is possible to prevent the gas ejected into the exhaust path 33 from flowing into the housing 61 and adhering to the light receiving element 62. Moreover, by using, for example, a semiconductor laser as the light source 52, it is possible to reduce the size and cost of the light emitting unit 50.

[0042] As described above, the light emitting unit 50 is provided with the emission lens unit 53, which can adjust the light beam emitted from the light source 52 to an arbitrary light beam, and can facilitate light reception at the light receiving unit 60. By adjusting the light beam emitted from the light source 52 by the emission lens unit 53 to a parallel light beam as an infinite system, the light intensity can be increased to a more distant point.

[0043] Furthermore, by adjusting the light flux emitted from the light source 52 by the emission lens unit 53 to a light flux having an arbitrary diffusion angle as a finite system, gas can be detected stably even if a positional deviation occurs on the light receiving unit 60 side. When the battery module 100 is mounted on a vehicle, the light incident on the light receiving unit 60 may move slightly due to vibrations from the vehicle. In this case, by adjusting the light flux to a light flux having a diffusion angle by the emission lens unit 53, it is possible to ensure that the light receiving unit 60 can always receive light even with slight movements of the light.

[0044] As described above, the light receiving section 60 is provided with the light receiving lens section 63, which can adjust the light beam incident on the light receiving element 62 to an arbitrary light beam to correspond to the size of the light receiving area of ​​the light receiving element 62.

[0045] The exhaust path 33 is defined by the shielding portion 41 of the cover plate 40, a pair of wall portions 34 surrounding the sides of each opening 32, and each wall surface of the base plate 31. Each of the above-mentioned wall surfaces facing the exhaust path 33 and defining the exhaust path 33 is colored black or the like to suppress light reflection, thereby preventing light that hits the gas from being reflected by the wall surface and reaching the light receiving unit 60. By suppressing reflection of light that hits the gas by the wall surface, the battery module 100 can reliably detect a decrease in light intensity at the time of gas ejection at the light receiving unit 60.

[0046] (Modification) Fig. 7A is a schematic cross-sectional view showing the configuration of a light emitting unit 50 according to a modified example, and Fig. 7B is a schematic cross-sectional view showing the configuration of a light receiving unit 60 according to a modified example. The light emitting unit 50 has a lens-shaped transparent window 54 that can adjust the luminous flux emitted from the light source 52 to an arbitrary luminous flux. The transparent window 54 transmits the luminous flux emitted from the light source 52 to the exhaust path 33 and prevents gas discharged from the battery 20 to the exhaust path 33 from flowing into the housing 51.

[0047] In addition, the light beam emitted from the light source 52 can be adjusted to an arbitrary light beam by the transparent window 54. The light beam emitted from the light source 52 is adjusted to a parallel light beam as an infinite system, or a light beam having an arbitrary diffusion angle as a finite system. The light emitting unit 50 can be made compact by giving the transparent window 54 a function as a lens.

[0048] The light receiving unit 60 has a lens-shaped transparent window 64 that can adjust the light flux incident on the light receiving element 62 to an arbitrary light flux. The transparent window 64 transmits the light flux from the exhaust path 33 into the housing 61 and prevents gas discharged from the battery 20 to the exhaust path 33 from flowing into the housing 61.

[0049] In addition, the transparent window 64 can adjust the light flux transmitted into the housing 61 to an arbitrary light flux, for example, the light flux transmitted into the housing 61 can be condensed and transmitted to the light receiving element 62. The light receiving unit 60 can be made smaller by making the transparent window 64 function as a lens.

[0050] 8 is a cross-sectional schematic diagram showing the configuration of a light emitting unit 50 according to another modified example. The light emitting unit 50 has a half mirror 55 and a light amount detection unit 56. The half mirror 55 reflects a portion of the light from the light source 52 and causes it to enter the light amount detection unit 56. The light amount detection unit 56 detects a portion of the light emitted from the light source 52 and detects the intensity of the light emitted from the light source 52. The half mirror 55 transmits the light other than the reflected portion of the light to the discharge path 33 side.

[0051] The half mirror 55 and the light amount detection unit 56 are provided inside the light emission unit 50, outside the exhaust path 33, and can detect the intensity of the light emitted by the light source 52 without being affected by the gas emitted from the battery 20.

[0052] The above description is based on the embodiments of the present invention. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

[0053] The embodiment may be specified by the following items. [Item 1] a battery stack (2) in which a plurality of batteries (20) each having a valve portion (24) for ejecting gas are stacked in a first direction; a discharge path (33) for discharging gas ejected from the valve portion (24) in a second direction intersecting the first direction; a light emitting portion (50) provided at one end side in the first direction of the battery stack (2) and emitting light to the discharge path (33); a light receiving section (60) provided at the other end side in the first direction of the battery stack (2) and configured to receive light emitted from the light emitting section (50); The battery module (100) is characterized by comprising: a battery module (100) configured to detect gas emitted from the battery (20), thereby improving the safety of the battery module (100). [Item 2] The battery module (100) according to item 1, wherein some of the batteries (20) are electrically connected in parallel. Thus, when a voltage abnormality occurs in a battery (20) included in a block connected in parallel and gas is emitted, the battery module (100) can detect the gas emission and detect the abnormal state of the battery (20). [Item 3] The battery module (100) according to item 1 or 2, wherein the light emitting section (50) and the light receiving section (60) each have a transparent window (54, 64) facing the exhaust path, so that the battery module (100) can prevent the gas ejected into the exhaust path (33) from adhering to the light source (52) and the light receiving element (62). [Item 4] The battery module (100) according to any one of items 1 to 3, wherein the light emitting section (50) has a light source (52) and an emitting lens section (53) capable of adjusting the luminous flux emitted from the light source (52) to an arbitrary luminous flux. This allows the battery module (100) to easily receive light at the light receiving section (60) by adjusting the luminous flux emitted from the light source (52) to an arbitrary luminous flux. [Item 5] The battery module (100) according to item 4, wherein the emission lens portion (53) is adjustable to a finite system light beam having a divergence angle. This allows the battery module (100) to stably detect gas even when the light receiving portion (60) is misaligned. [Item 6] The battery module (100) according to item 4 or 5, wherein the light receiving section (60) has a light receiving element (62) and a light receiving lens section (63) capable of adjusting the light flux incident on the light receiving element (62) to an arbitrary light flux. This allows the battery module (100) to adjust the light flux incident on the light receiving element (62) to an arbitrary light flux to correspond to the size of the light receiving area of ​​the light receiving element (62). [Item 7] The light emitting portion (50) has a light source (52), the transparent window (54) of the light emitting portion (50) is capable of adjusting the light flux emitted from the light source (52) to an arbitrary light flux; The light receiving section (60) has a light receiving element (62), The battery module (100) according to item 3, characterized in that the transparent window (64) of the light receiving section (60) is capable of adjusting the light flux incident on the light receiving element (62) to an arbitrary light flux. This allows the battery module (100) to have a light emitting section (50) and a light receiving section (60) that are miniaturized by providing the transparent windows (54, 64) with a lens function. [Item 8] The battery module (100) according to any one of items 4 to 7, wherein the light source (52) is a semiconductor laser. Thus, by using a semiconductor laser as the light source (52), the battery module (100) can be made smaller and less expensive. [Item 9] The battery module (100) according to any one of items 1 to 8, further comprising a light amount detection unit (56) for detecting the amount of light emitted from the light emission unit (50) provided outside the discharge path (33). This allows the battery module (100) to detect the intensity of the light emitted by the light source (52) without being affected by gas emitted from the battery (20). [Item 10] The battery module (100) according to any one of items 1 to 9, wherein the exhaust path (33) is partitioned by a wall surface that suppresses reflection of the light emitted from the light emitting portion (50). In this way, the battery module (100) can reliably detect a decrease in light intensity at the time of gas ejection in the light receiving portion (60) by suppressing reflection of light that hits the gas on the wall surface. [Explanation of symbols]

[0054] 2 battery stack, 20 battery, 24 valve portion, 33 exhaust path, 50 light emitting portion, 52 light source, 53 light emitting lens portion, 54 transparent window, 60 light receiving portion, 62 light receiving element, 63 light receiving lens portion, 64 transparent window, 100 battery module.

Claims

1. a battery stack in which a plurality of batteries, each having a valve portion for ejecting gas, are stacked in a first direction; an exhaust path that exhausts gas ejected from the valve portion in a second direction intersecting the first direction; a light emitting portion provided at one end side of the battery stack in the first direction and configured to emit light to the discharge path; a light receiving portion provided at the other end of the battery stack in the first direction and configured to receive the light emitted from the light emitting portion; a housing including end plates located at both ends of the battery stack in the first direction, side plates that sandwich the end plates and cover side surfaces of the battery stack in the second direction, and a base plate that covers a bottom of the battery stack on one side in a third direction that intersects with the first direction and the second direction; a duct plate provided to block the exhaust path and covering the other side of the battery stack in the third direction; a cover plate covering the other side of the duct plate in the third direction, the exhaust path is formed to extend in the first direction between the duct plate and the cover plate and is open at the one end side and the other end side in the first direction, the light emitting portion faces the discharge path and is provided on the end plate on the one end side in the first direction, The battery module, wherein the light receiving portion faces the discharge path and is provided on the end plate on the other end side in the first direction.

2. 2. The battery module according to claim 1, wherein some of the batteries are electrically connected in parallel.

3. 3. The battery module according to claim 1, wherein the light emitting portion and the light receiving portion each have a transparent window facing the discharge path.

4. 4. The battery module according to claim 1, wherein the light emitting section has a light source and an emitting lens section capable of adjusting a light flux emitted from the light source to an arbitrary light flux.

5. 5. The battery module according to claim 4, wherein the emission lens portion is adjustable to a finite system light flux having a divergence angle.

6. 6. The battery module according to claim 4, wherein the light receiving section includes a light receiving element and a light receiving lens section capable of adjusting a light flux incident on the light receiving element to an arbitrary light flux.

7. The light emitting unit has a light source, the transparent window of the light emitting unit is capable of adjusting the light flux emitted from the light source to an arbitrary light flux, The light receiving unit has a light receiving element, 4. The battery module according to claim 3, wherein the transparent window of the light receiving portion is capable of adjusting the light flux incident on the light receiving element to an arbitrary light flux.

8. 8. The battery module according to claim 4, wherein the light source is a semiconductor laser.

9. 9. The battery module according to claim 1, further comprising a light amount detector disposed outside the discharge path and configured to detect an amount of light emitted from the light emitting portion.

10. The battery module according to claim 1 , wherein the discharge path is defined by a wall surface that suppresses reflection of the light emitted from the light emitting portion.

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