Battery pack and battery panel

Abstract

To provide a battery pack that can easily detect expansion of a battery cell.SOLUTION: A battery pack includes a plurality of battery cells, a plurality of bus bars, a substrate, a lower case, an upper case, and a sign portion. The bus bars electrically connect the plurality of battery cells. The substrate is electrically connected to the battery cells. The lower case has a bottom wall for supporting the battery cells, a first side wall that protrudes from the bottom wall and surrounds the battery cells, and an outer peripheral surface that is provided on the first side wall and faces outward, and at least partially houses the battery cells. The upper case has a second side wall that is surrounded by the first side wall and attached to the first side wall by a snap fit, and a covering surface that is provided on the second side wall, faces outward, and is covered by the first side wall, and houses the substrate. The sign portion is provided on the covering surface and has a color different from the color of the outer peripheral surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a battery pack and a battery panel. [Background technology]

[0002] Conventionally, a battery pack including a plurality of battery cells and a case for accommodating the plurality of battery cells is known. Also, a battery panel (battery system) including a plurality of battery packs is known. The battery pack or battery panel is used as a power source for, for example, a vehicle, an industrial machine, or other devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2023-505981 Summary of the Invention [Problem to be solved by the invention]

[0004] Battery cells may expand due to gas generation caused by decomposition of the electrolyte, positive electrode material, or negative electrode material. The presence or absence of expansion of battery cells may be checked during inspection of assembled batteries or battery panels, such as maintenance inspections and deterioration diagnosis. If it is difficult to detect the expansion of battery cells, the inspection burden increases.

[0005] One example of a problem to be solved by the present invention is to provide a battery pack and a battery panel that can easily detect expansion of a battery cell. [Means for solving the problem]

[0006] The battery pack according to one embodiment includes a plurality of battery cells, a plurality of bus bars, a substrate, a lower case, an upper case, and a sign. Each of the plurality of bus bars electrically connects two of the plurality of battery cells. The substrate is electrically connected to the plurality of battery cells via the plurality of bus bars. The lower case has a bottom wall supporting the plurality of battery cells, a first side wall protruding from the bottom wall and surrounding the plurality of battery cells, and an outer peripheral surface provided on the first side wall and facing outward, and at least partially houses the plurality of battery cells. The upper case has a second side wall surrounded by the first side wall and attached to the first side wall by a snap fit, and a covering surface provided on the second side wall, facing outward, and covered by the first side wall, and houses the substrate. The sign is provided on the covering surface and has a color different from the color of the outer peripheral surface. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an exemplary front view that illustrates a battery panel according to the first embodiment. [Diagram 2] FIG. 2 is an exemplary perspective view showing the battery pack of the first embodiment. [Diagram 3] FIG. 3 is an exemplary exploded perspective view showing the battery pack of the first embodiment. [Figure 4] FIG. 4 is an exemplary cross-sectional view that illustrates the battery pack of the first embodiment. [Diagram 5] FIG. 5 is an exemplary plan view that illustrates the sensor of the first embodiment. [Figure 6] FIG. 6 is an exemplary perspective view showing an expanded battery pack of the first embodiment. [Figure 7] FIG. 7 is a cross-sectional view that illustrates a schematic view of an expanded battery pack and a sensor band according to the first embodiment. [Figure 8] FIG. 8 is an exemplary perspective view showing a battery pack according to the second embodiment. [Figure 9] FIG. 9 is an exemplary front view that illustrates a battery panel according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (First embodiment) The first embodiment will be described below with reference to FIGS. 1 to 7. In this specification, the vertically upward direction is basically defined as the upward direction, and the vertically downward direction is basically defined as the downward direction. In this specification, the components according to the embodiment and the explanation of the components may be described in a plurality of ways. The components and their explanations are merely examples and are not limited by the expressions in this specification. The components may be specified by names different from those in this specification. The components may be described by expressions different from those in this specification.

[0009] In the following description, "inhibit" is defined as, for example, preventing the occurrence of an event, action, or effect, or reducing the magnitude of an event, action, or effect.

[0010] 1 is an exemplary front view that illustrates a battery panel (battery system) 10 according to a first embodiment. The battery panel 10 is mounted as a power source in an apparatus 1. The apparatus 1 is, for example, a railroad vehicle, an industrial machine, a computer system, or any other type of apparatus.

[0011] As shown in each drawing, for the sake of convenience, an X-axis, a Y-axis, and a Z-axis are defined in this specification. The X-axis, the Y-axis, and the Z-axis are perpendicular to each other. The X-axis is set along the width of the battery panel 10. The Y-axis is set along the depth of the battery panel 10. The Z-axis is set along the height of the battery panel 10.

[0012] Furthermore, in this specification, an X direction, a Y direction, and a Z direction are defined. The X direction is a direction along the X axis, and includes a +X direction indicated by an arrow on the X axis, and a -X direction opposite to the arrow on the X axis. The Y direction is a direction along the Y axis, and includes a +Y direction indicated by an arrow on the Y axis, and a -Y direction opposite to the arrow on the Y axis. The Z direction is a direction along the Z axis, and includes a +Z direction indicated by an arrow on the Z axis, and a -Z direction opposite to the arrow on the Z axis. In this embodiment, the +Z direction is the upward direction, and the -Z direction is the downward direction. The Z direction may be different from the vertical direction.

[0013] The battery panel 10 has a plurality of assembled batteries 11, a housing 12, a plurality of wirings 13, and a measurement system 14. The battery panel 10 further has various components such as a Battery Management Unit (BMU) that controls the plurality of assembled batteries 11, a host controller that controls the entire battery panel 10, and a cooling device that cools the plurality of assembled batteries 11.

[0014] Fig. 2 is an exemplary perspective view showing the battery pack 11 of the first embodiment. Fig. 3 is an exemplary exploded perspective view showing the battery pack 11 of the first embodiment. Fig. 4 is an exemplary cross-sectional view that generally shows the battery pack 11 of the first embodiment.

[0015] 3, each of the multiple assembled batteries 11 has multiple battery cells 21, a case 22, multiple bus bars 23, a monitoring board 24, a positive terminal 25, a negative terminal 26, and multiple indicators 27. The battery cells 21 are also called single cells. The monitoring board 24 is also called a CMU (Cell Monitoring Unit) and is an example of a board.

[0016] The battery cells 21 are non-aqueous electrolyte secondary batteries such as lithium ion batteries. At least one of the battery cells 21 may be another battery. Each of the battery cells 21 has a container 31, a positive terminal 32, a negative terminal 33, and a content 34.

[0017] The container 31 is formed in a substantially rectangular box shape. The container 31 has a top surface 31a, two long side surfaces 31b, and two short side surfaces 31c. The top surface 31a is formed in a rectangular shape that spreads along the XY plane and extends in the Y direction. The top surface 31a faces substantially in the +Z direction.

[0018] The positive electrode terminal 32 and the negative electrode terminal 33 are provided on the upper surface 31a. The positive electrode terminal 32 and the negative electrode terminal 33 are spaced apart from each other in the Y direction. Furthermore, a release valve 36 is provided on the upper surface 31a. The release valve 36 is also called a rupture or a vent.

[0019] The release valve 36 is located between the positive electrode terminal 32 and the negative electrode terminal 33. The release valve 36 is, for example, a portion of the container 31 that is formed thin and has a groove. The groove of the release valve 36 is separated from the inside of the container 31.

[0020] Each of the two long side surfaces 31b is formed in a substantially rectangular shape extending along the YZ plane. One long side surface 31b faces substantially in the +X direction, and the other long side surface 31b faces substantially in the -X direction. Each of the two short side surfaces 31c is formed in a substantially rectangular shape extending along the XZ plane and in the Z direction. One short side surface 31c faces substantially in the +Y direction, and the other short side surface 31c faces substantially in the -Y direction. The length of the long side surface 31b in the Y direction is longer than the length of the short side surface 31c in the X direction.

[0021] The contents 34 include, for example, a positive electrode material, a negative electrode material, a separator, and a non-aqueous electrolyte. The positive electrode material is electrically connected to a positive electrode terminal 32. The negative electrode material is electrically connected to a negative electrode terminal 33. The separator is disposed between the positive electrode material and the negative electrode material. The positive electrode material, the negative electrode material, and the separator are, for example, wound and contained in a container 31 together with the electrolyte.

[0022] The multiple battery cells 21 are arranged in multiple rows. The long side surface 31b of one battery cell 21 faces the long side surface 31b of another battery cell 21. Furthermore, the short side surface 31c of one battery cell 21 faces the short side surface 31c of the other battery cell 21.

[0023] The case 22 is made of synthetic resin and formed into a rectangular box shape. The case 22 houses a plurality of battery cells 21, a plurality of bus bars 23, and a monitoring board 24. The case 22 has a lower case 41 and an upper case .

[0024] 4, the lower case 41 has a bottom wall 51 and a side wall 52. The side wall 52 is an example of a first side wall. The bottom wall 51 is formed in a substantially rectangular plate shape that spreads along the XY plane and extends in the Y direction. The side wall 52 protrudes from an edge of the bottom wall 51 in substantially the +Z direction and is formed in a substantially rectangular frame shape.

[0025] The lower case 41 at least partially accommodates the multiple battery cells 21. The bottom wall 51 supports the multiple battery cells 21. As shown in Fig. 4, an interposer 54 may be interposed between the battery cells 21 and the bottom wall 51. The interposer 54 is, for example, an adhesive or a polymer sheet that fixes the battery cells 21 to the bottom wall 51. The side wall 52 surrounds the multiple battery cells 21.

[0026] The side wall 52 has an outer peripheral surface 52a and an inner peripheral surface 52b. In other words, the outer peripheral surface 52a and the inner peripheral surface 52b are provided on the side wall 52. The outer peripheral surface 52a faces the outside of the lower case 41. The inner peripheral surface 52b is located on the opposite side to the outer peripheral surface 52a and faces the inside of the lower case 41.

[0027] As shown in FIG. 3, the outer peripheral surface 52a has two long sides 52c and two short sides 52d. Each of the two long sides 52c is formed in a rectangular shape that spreads along the YZ plane and extends in the Y direction. One long side 52c faces approximately in the +X direction, and the other long side 52c faces approximately in the -X direction. Each of the two short sides 52d is formed in a rectangular shape that spreads along the XZ plane and extends in the X direction. One short side 52d faces approximately in the +Y direction, and the other short side 52d faces approximately in the -Y direction. The length of the long side 52c in the Y direction is longer than the length of the short side 52d in the X direction.

[0028] Furthermore, the side wall 52 has an upper end portion 56. The upper end portion 56 is provided at the end portion of the side wall 52 in the +Z direction and surrounds the multiple battery cells 21. The upper end portion 56 is thinner than the end portion of the side wall 52 in the -Z direction, for example.

[0029] The upper end 56 has a part of the outer circumferential surface 52a and a part of the inner circumferential surface 52b. As shown in Fig. 4, the outer circumferential surface 52a of the upper end 56 is continuous with the outer circumferential surface 52a of the other portion of the side wall 52. On the other hand, the inner circumferential surface 52b of the upper end 56 is closer to the outer circumferential surface 52a than the inner circumferential surface 52b of the other portion of the side wall 52. Note that the upper end 56 is not limited to this example.

[0030] A plurality of holes 57 are provided in the upper end portion 56. Each of the plurality of holes 57, for example, penetrates the upper end portion 56 and opens to the outer peripheral surface 52a and the inner peripheral surface 52b of the upper end portion 56. Note that the holes 57 may be open only to the inner peripheral surface 52b.

[0031] The upper case 42 has a frame 61 and a cover 62 attached to each other. The frame 61 has a middle wall 64, a side wall 65, and a plurality of claws 66. The side wall 65 is an example of a second side wall.

[0032] The middle wall 64 is formed in a generally rectangular plate shape that spreads along the XY plane and extends in the Y direction. The middle wall 64 is spaced in the +Z direction from the bottom wall 51 of the lower case 41. The side walls 52 protrude in the +Z and -Z directions from the edges of the middle wall 64 and are formed in a generally rectangular frame shape.

[0033] In this embodiment, the side wall 65 surrounds the multiple battery cells 21. The multiple battery cells 21 are disposed between the bottom wall 51 of the lower case 41 and a middle wall 64 of the upper case 42. The positive electrode terminals 32 and negative electrode terminals 33 of the battery cells 21 are exposed, for example, through holes provided in the middle wall 64. It is noted that the middle wall 64 may be omitted.

[0034] The side wall 65 has an outer circumferential surface 65a and an inner circumferential surface 65b. The outer circumferential surface 65a faces the outside of the upper case 42. The inner circumferential surface 65b is located on the opposite side to the outer circumferential surface 65a and faces the inside of the upper case 42.

[0035] As shown in FIG. 3, the outer peripheral surface 65a has two long sides 65c and two short sides 65d. Each of the two long sides 65c is formed in a rectangular shape that spreads along the YZ plane and extends in the Y direction. One long side 65c faces approximately in the +X direction, and the other long side 65c faces approximately in the -X direction. Each of the two short sides 65d is formed in a rectangular shape that spreads along the XZ plane and extends in the X direction. One short side 65d faces approximately in the +Y direction, and the other short side 65d faces approximately in the -Y direction. The length of the long side 65c in the Y direction is longer than the length of the short side 65d in the X direction.

[0036] Furthermore, the side wall 65 has a lower end portion 68. The lower end portion 68 is provided at the end portion of the side wall 65 in the -Z direction and surrounds the multiple battery cells 21. The lower end portion 68 is thinner than, for example, the end portion of the side wall 65 in the +Z direction.

[0037] The lower end 68 has a part of the outer circumferential surface 65a and a part of the inner circumferential surface 65b. The outer circumferential surface 65a of the lower end 68 has a covered surface 68a. That is, the covered surface 68a is provided on the side wall 65 and faces the outside of the upper case 42. The covered surface 68a is closer to the inner circumferential surface 65b than the outer circumferential surface 65a of the other part of the side wall 65. As shown in FIG. 4, the inner circumferential surface 65b of the lower end 68 is continuous with the inner circumferential surface 65b of the other part of the side wall 65. It should be noted that the lower end 68 is not limited to this example.

[0038] The lower end 68 of the side wall 65 fits inside the upper end 56 of the side wall 52. Therefore, the lower end 68 of the side wall 65 is surrounded by the upper end 56 of the side wall 52. Furthermore, the covered surface 68a of the lower end 68 is covered by the upper end 56 of the side wall 52. The covered surface 68a and the inner circumferential surface 52b of the upper end 56 face each other.

[0039] The claws 66 protrude from a covering surface 68a of the lower end portion 68. Each of the claws 66 fits into a corresponding one of the holes 57. This allows the side wall 65 of the frame 61 to be attached to the side wall 52 of the lower case 41 by snap-fitting. Alternatively, a hole may be provided in the side wall 65, and a claw may be provided in the side wall 52.

[0040] The lid 62 is attached to a side wall 65 of the frame 61 at a position spaced apart from the middle wall 64 in the +Z direction. The multiple bus bars 23 and the monitoring board 24 are housed in the upper case 42 so as to be located between the lid 62 and the middle wall 64. The bus bars 23 may be disposed in other positions.

[0041] Each of the multiple bus bars 23 electrically connects two of the multiple battery cells 21. For example, each of the multiple bus bars 23 electrically connects the positive electrode terminal 32 of one of two adjacent battery cells 21 to the negative electrode terminal 33 of the other.

[0042] The monitoring board 24 is, for example, a printed circuit board (PCB) and has various electronic components such as a cell monitoring IC. The monitoring board 24 is electrically connected to the multiple battery cells 21 via the multiple bus bars 23 and controls the multiple battery cells 21. For example, the monitoring board 24 measures the voltage and temperature of the battery cells 21. The monitoring board 24 is electrically connected to the BMU.

[0043] 2, the case 22 further has an end face 22a. The end face 22a is formed, for example, by one short side face 52d of the lower case 41 and one short side face 65d of the upper case 42, and faces approximately in the -Y direction.

[0044] The positive terminal 25 and the negative terminal 26 are provided on the end surface 22a. The positive terminal 25 and the negative terminal 26 are input / output terminals of the battery pack 11. The positive terminal 25 and the negative terminal 26 are electrically connected to the multiple battery cells 21 connected in series and parallel by multiple bus bars 23.

[0045] 4, the case 22 further has two long side surfaces 22b and 22c and an upper surface 22d. The long side surface 22b is an example of a first surface. The long side surface 22c is an example of a second surface. The upper surface 22d is an example of a third surface.

[0046] The long side surface 22b is formed, for example, by one long side surface 52c of the lower case 41 and one long side surface 65c of the upper case 42, and faces approximately in the +X direction. The long side surface 22c is located on the opposite side of the long side surface 22b. The long side surface 22c is formed, for example, by the other long side surface 52c of the lower case 41 and the other long side surface 65c of the upper case 42, and faces approximately in the -X direction.

[0047] The top surface 22d is formed, for example, by the lid 62 of the upper case 42, and faces approximately in the +Z direction. The top surface 22d extends between an edge of the long side surface 22b in the +Z direction and an edge of the long side surface 22c in the +Z direction.

[0048] 3, the sign portion 27 is provided on the covering surface 68a. The sign portion 27 is, for example, a reflective material that diffusely reflects light. Each of the multiple sign portions 27 is attached to the covering surface 68a between two adjacent claws 66.

[0049] The sign unit 27 is provided on a portion of the covered surface 68a that is included in the long side surface 65c. The sign unit 27 is attached to the covered surface 68a at approximately the center of the long side surface 65c in the Y direction. The position of the sign unit 27 is not limited to this example.

[0050] The case 22 is made of, for example, a black synthetic resin. Therefore, the outer peripheral surfaces 52a, 65a of the side walls 52, 65 are black. On the other hand, the sign portion 27 reflects light and is, for example, a fluorescent color. Therefore, the sign portion 27 has a color different from the color of the outer peripheral surfaces 52a, 65a. The difference in color is, for example, a difference in at least one of hue, saturation, brightness, and reflectance.

[0051] For example, the contrast between the color of the marking portion 27 and the color of the outer peripheral surfaces 52a, 65a is greater than the contrast between the color of the positive terminal 25 or the negative terminal 26 and the color of the outer peripheral surfaces 52a, 65a. The color of the positive terminal 25 and the negative terminal 26 is, for example, copper color. Note that the colors of the positive terminal 25, the negative terminal 26, the marking portion 27, and the outer peripheral surfaces 52a, 65a are not limited to this example.

[0052] The sign portion 27, together with the covering surface 68a, is covered by the upper end portion 56 of the side wall 52. Therefore, under normal circumstances, the sign portion 27 is not exposed but is hidden. Note that a part of the sign portion 27 may be slightly visible from the outside, for example, through a hole 57.

[0053] 1, the housing 12 has two side walls 71, a bottom plate 72, a top plate 73, a back plate 74, and at least one shelf plate 75. Note that the housing 12 is not limited to this example, and may be integrated with the housing of the device 1, for example.

[0054] The two side walls 71 are formed in plate shapes extending along the YZ plane and are spaced apart from each other in the X direction. The bottom plate 72 and the top plate 73 extend approximately in the X direction between the two side walls 71. The top plate 73 is spaced apart from the bottom plate 72 in the +Z direction. The back plate 74 closes the end of the housing 12 in the +Y direction.

[0055] The shelf board 75 is located between the two side walls 71, and is also located between the bottom board 72 and the top board 73. When the housing 12 has a plurality of shelves 75, the plurality of shelves 75 are arranged with intervals in the Z direction.

[0056] The housing 12 is provided with a storage chamber 76 and an opening 77. The storage chamber 76 is provided inside the housing 12. The storage chamber 76 is formed (defined, partitioned) by, for example, two side walls 71, a bottom plate 72, a top plate 73, and a back plate 74. A shelf plate 75 is disposed in the storage chamber 76. The opening 77 is provided, for example, at an end of the housing 12 in the -Y direction, and connects the storage chamber 76 to the outside of the housing 12. The housing 12 may further have a door that closes the opening 77 in an openable and closable manner.

[0057] The multiple battery packs 11 are accommodated in the accommodation chamber 76. For example, at least two of the multiple battery packs 11 are placed on the bottom plate 72, and at least other two of the multiple battery packs 11 are placed on the shelf plate 75. Therefore, the multiple battery packs 11 are arranged to form two rows L1 and L2.

[0058] The plurality of assembled batteries 11 forming row L1 are supported by a bottom plate 72. The plurality of assembled batteries 11 forming row L2 are supported by a shelf plate 75. Therefore, row L2 is spaced apart from row L1 in the +Z direction.

[0059] In each of the columns L1 and L2, the multiple battery packs 11 are arranged in the X direction with gaps between them. In each of the columns L1 and L2, the long side surfaces 22b and 22c of one of two adjacent battery packs 11 face each other. Therefore, the portion of the covered surface 68a of one battery pack 11 that is included in the long side surface 65c faces the other battery pack 11.

[0060] The end surface 22a faces the opening 77. Therefore, the positive electrode terminal 25 and the negative electrode terminal 26 provided on the end surface 22a are exposed to the outside of the housing 12 through the opening 77 when, for example, the door of the housing 12 is opened.

[0061] The multiple wirings 13 electrically connect one positive terminal 25 of each pair of adjacent batteries 11 to the negative terminal 26 of the other battery. The multiple battery packs 11 electrically connected by the multiple wirings 13 are connected to a main circuit of the device 1 via, for example, a maintenance service disconnector, a fuse, a current sensor, and a contactor. A host controller of the battery panel 10 controls the service disconnector, the contactor, and the BMU.

[0062] The measurement system 14 includes, for example, a sensor 81, an AD converter 82, and a determination device 83. However, the measurement system 14 is not limited to this example. The sensor 81 includes a sensor band 85 and a signal conditioner 86.

[0063] 5 is an exemplary plan view that illustrates the sensor 81 of the first embodiment. In FIG. 5, the sensor band 85 extends linearly for ease of understanding. The sensor band 85 includes a flexible printed circuit board (FPC) 91 and two reinforcing plates 92.

[0064] The FPC 91 is formed in a thin strip shape. The FPC 91 has a base film 95, a plurality of strain gauges 96, two through holes 97, and a plurality of wiring patterns 98. In other words, the FPC 91 is provided with a plurality of strain gauges 96.

[0065] The base film 95 is made of an insulator such as polyimide (PI). An example of a material suitable for the base film 95 is a material that complies with UL94V-0, which indicates flame retardancy. The strain gauges 96 and the wiring pattern 98 are made of a conductor such as copper, and are provided on the surface of the base film 95. The FPC 91 further has a cover film that covers the strain gauges 96 and the wiring pattern 98.

[0066] The multiple strain gauges 96 are arranged at intervals in the longitudinal direction of the FPC 91. Two through holes 97 are provided at both ends of the FPC 91 in the longitudinal direction. Each of the multiple wiring patterns 98 electrically connects two adjacent strain gauges 96, or electrically connects one strain gauge 96 to one through hole 97. The multiple strain gauges 96 are connected in series with each other.

[0067] The reinforcing plate 92 is, for example, a synthetic resin plate conforming to FR-1 or FR-4, and may be, for example, a UL94V-0 compliant product. The reinforcing plate 92 is attached to both ends of the FPC 91 in the longitudinal direction. The reinforcing plate 92 reinforces both ends of the FPC 91 in which the through holes 97 are provided.

[0068] 4, the sensor band 85 is attached to the case 22 of the multiple battery packs 11. The sensor band 85 extends along the long sides 22b, 22c and the top surface 22d of each of the multiple battery packs 11. The sensor band 85 is attached to the case 22 with a predetermined slack.

[0069] 2, on long sides 22b, 22c, sensor band 85 extends substantially in the Z direction across upper end 56 of side wall 52. In other words, sensor band 85 extends across the boundary between side wall 52 and side wall 65. Note that the path of sensor band 85 is not limited to this example.

[0070] 1, one sensor strip 85 extends along a path that can be traced in one stroke, and is attached to the cases 22 of the multiple battery packs 11. For example, one sensor strip 85 is laid along the long side surfaces 22b, 22c and top surfaces 22d of all the battery packs 11 included in row L1, laid across the shelf board 75, and laid along the long side surfaces 22b, 22c and top surfaces 22d of all the battery packs 11 included in row L2.

[0071] The sensor strip 85 does not have to be provided on all of the assembled batteries 11. For example, the sensor strip 85 may be provided on one assembled battery 11 included in row L1, provided across the shelf board 75, and provided on one assembled battery 11 included in row L2. In other words, the sensor strip 85 may be provided on the assembled battery 11 selected as a sample in each of the multiple rows L1 and L2.

[0072] 5, the signal conditioner 86 has four wires 101, 102, 103, and 104, three resistors 105, 106, and 107, and a galvanometer 108. The resistor 105 is an example of a first resistor. The resistor 106 is an example of a second resistor. The resistor 107 is an example of a third resistor.

[0073] One end 101a of the wiring 101 is connected to one end 102a of the wiring 102. The other end 101b of the wiring 101 is connected to one end 103a of the wiring 103. The wiring 104 connects the end 101a of the wiring 101 and the other end 103b of the wiring 103.

[0074] The resistor 105 is provided on the wiring 101. The resistor 106 is provided on the wiring 102. The resistor 107 is provided on the wiring 103. The galvanometer 108 is provided on the wiring 104. The electrical resistances of the resistors 105, 106, and 107 are approximately constant.

[0075] The other end 102b of the wiring 102 is electrically connected to one of the through holes 97 of the sensor band 85. The other end 103b of the wiring 103 is electrically connected to the other through hole 97 of the sensor band 85.

[0076] The sensor 81 includes a bridge circuit BC. The bridge circuit BC includes the above-mentioned wirings 101, 102, 103, and 104, resistors 105, 106, and 107, a galvanometer 108, and a variable resistor RX. The variable resistor RX is an example of a fourth resistor.

[0077] The variable resistor RX has a sensor band 85. That is, the variable resistor RX has a plurality of strain gauges 96. The electric resistance of the variable resistor RX (sensor band 85) varies as the strain gauges 96 expand and contract in the longitudinal direction of the FPC 91.

[0078] An end 101b of the wiring 101 and an end 102b of the wiring 102 are electrically connected to a power source E. When the electrical resistance of the variable resistor RX varies, the output signal of the galvanometer 108 varies. The signal conditioner 86 outputs the output signal of the galvanometer 108 to the AD converter 82 in Fig. 1. The AD converter 82 converts the analog signal output by the galvanometer 108 into a digital signal.

[0079] The determination device 83 is, for example, a computer such as a microcomputer or a personal computer. That is, the determination device 83 has a control device such as a CPU, a storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an auxiliary storage device such as a HDD (Hard Disk Drive) or a flash memory. The determination device 83 obtains the output value of the galvanometer 108 from the AD converter 82. The determination device 83 may also be a PLC (Programmable Logic Controller).

[0080] Fig. 6 is an exemplary perspective view showing an expanded battery pack 11 according to the first embodiment. Note that Fig. 6 omits a sensor band 85. Fig. 7 is a cross-sectional view that diagrammatically shows the expanded battery pack 11 and the sensor band 85 according to the first embodiment.

[0081] Decomposition of the electrolyte, positive electrode material, or negative electrode material of the contents 34 of the battery cell 21 may generate gas inside the container 31. If the gas increases the internal pressure of the container 31, the battery cell 21 may expand.

[0082] The battery cell 21 expands so that the long side surface 31b and the short side surface 31c of the container 31 protrude outward. The long side surface 31b expands more easily than the short side surface 31c. When the battery cell 21 expands beyond a predetermined deformation amount, it pushes the side walls 52, 65 of the case 22 outward. In other words, as the battery cell 21 expands, the case 22 also expands.

[0083] The end of the side wall 52 in the -Z direction is connected to the bottom wall 51. For this reason, when the battery cell 21 presses the side wall 52, the amount of deformation of the upper end 56 is larger than the amount of deformation of the end of the side wall 52 in the -Z direction. Furthermore, the amount of deformation of the portion of the upper end 56 that includes the long side surface 52c is maximum in the lower case 41.

[0084] When the battery cell 21 presses the side wall 65, the amount of deformation of the bottom end 68 is greater than that of the portion of the side wall 65 that is connected to the middle wall 64. Furthermore, the amount of deformation of the portion of the bottom end 68 that includes the long side surface 65c is greatest in the upper case 42.

[0085] In this embodiment, a portion of the upper end 56 including the long side surface 52c and a portion of the lower end 68 including the long side surface 65c form a maximum displacement part PD. The maximum displacement part PD is a part where the displacement due to the expansion of the case 22 is maximum.

[0086] The maximum displacement part PD is provided on the long side surfaces 22b, 22c of the case 22. The maximum displacement part PD is approximately in the center of the long side surfaces 22b, 22c in the Y direction, and is a part where the upper end part 56 of the side wall 52 and the lower end part 68 of the side wall 65 overlap. Note that the maximum displacement part PD is not limited to this example, and may be, for example, another part identified by an experiment in which the case 22 is expanded.

[0087] 4, the sensor band 85 is attached to the maximum displacement part PD of the long side surfaces 22b and 22c. On the long side surface 22b, one strain gauge 96 is attached to the maximum displacement part PD. Furthermore, on the long side surface 22c, another strain gauge 96 is attached to the maximum displacement part PD. Therefore, in this embodiment, two strain gauges 96 are attached to the case 22.

[0088] The strain gauge 96 may be attached to the maximum displacement part PD of only one of the long sides 22b, 22c. That is, at least one of the plurality of strain gauges 96 is attached to the maximum displacement part PD of each of the plurality of assembled batteries 11.

[0089] For example, the portion of sensor band 85 on which strain gauge 96 is provided is attached to maximum displacement part PD with adhesive or double-sided tape. Sensor band 85 may also be attached to long side surfaces 22b, 22c and top surface 22d with adhesive tape.

[0090] 7, when the case 22 expands, at least one of the two strain gauges 96 attached to the case 22 is pulled in the longitudinal direction. As a result, the electrical resistance of the variable resistor RX and the output signal of the galvanometer 108 vary.

[0091] The determination device 83 determines whether the output signal of the galvanometer 108 is outside a predetermined range. When the case 22 expands as shown in Figures 6 and 7, the output signal of the galvanometer 108 goes outside the range, and the determination device 83 determines that the case 22 of the assembled battery 11 has expanded. That is, the determination device 83 determines whether one or more cases 22 of the multiple assembled batteries 11 have expanded, based on the output signal of the galvanometer 108 of the sensor 81. The sensor 81 also detects the expansion of the cases 22 of the multiple assembled batteries 11.

[0092] 7, when the side walls 52, 65 are pressed by the battery cell 21 and deformed, the side wall 52 moves away from the side wall 65. In other words, the claws 66 come out of the holes 57 and the snap fit is released.

[0093] 6, when the snap fit is released and the side walls 52, 65 are separated from each other, the covered surface 68a of the side wall 65 and the marker portion 27 are exposed and not covered by the side wall 52. The side wall 65 is deformed so that the covered surface 68a faces obliquely upward. Therefore, the marker portion 27 can be easily seen through the gap between the side walls 52 and 65.

[0094] When inspecting the battery panel 10, such as for maintenance and inspection or deterioration diagnosis, a worker opens the door of the housing 12 and shines a light, for example, on the multiple assembled batteries 11. The exposed indicator 27 reflects the light. By visually checking the light reflected by the indicator 27, the worker can quickly confirm that the case 22 is expanded.

[0095] 1, an optical sensor 110 such as a color sensor may be disposed in the storage chamber 76 of the housing 12. The optical sensor 110 can optically detect the exposed mark portion 27. This makes it possible to detect the expansion of the case 22 without visual confirmation by an operator.

[0096] If the battery cells 21 expand, the multiple battery cells 21 will push against each other inside the case 22. This may cause the battery cells 21 and the bus bars 23 to move from their predetermined positions, resulting in a risk of electrical connection being cut off between the monitoring board 24 and the bus bars 23. However, the battery panel 10 of this embodiment detects the expansion of the battery cells 21 and the case 22 before the positions of the battery cells 21 and the bus bars 23 change significantly, and therefore can prevent electrical connection between the monitoring board 24 and the battery cells 21 via the bus bars 23 from being cut off.

[0097] If the battery cell 21 expands and the internal pressure of the container 31 exceeds a predetermined value, the release valve 36 breaks and the gas inside the container 31 is released to the outside through the release valve 36. This reduces the pressure inside the container 31. However, in the battery panel 10 of this embodiment, the expansion of the battery cell 21 and case 22 is detected before the gas is released from the release valve 36, so that the release of gas from the release valve 36 can be prevented.

[0098] In the battery panel 10 according to the first embodiment described above, the lower case 41 has a sidewall 52 that protrudes from the bottom wall 51 and surrounds the multiple battery cells 21, and an outer circumferential surface 52a that is provided on the sidewall 52 and faces outward. The lower case 41 at least partially houses the multiple battery cells 21. The upper case 42 has a sidewall 65 that is surrounded by the sidewall 52 and attached to the sidewall 52 by a snap fit, and a covered surface 68a that is provided on the sidewall 65, faces outward, and is covered by the sidewall 52. The marking portion 27 is provided on the covered surface 68a and has a color different from the color of the outer circumferential surface 52a.

[0099] The battery cell 21 may expand due to gas generation caused by decomposition of the electrolyte, the positive electrode material, or the negative electrode material. In normal conditions when the battery cell 21 is not expanded, the color of the appearance of the portion where the side wall 52 and the side wall 65 overlap is the color of the outer peripheral surface 52a. On the other hand, when the battery cell 21 housed in the lower case 41 expands beyond a predetermined deformation amount, the side wall 52 and the side wall 65 that are snap-fitted together are pushed outward by the battery cell 21. When the side wall 52 and the side wall 65 are deformed by being pushed by the battery cell 21, the snap fit is released and they are separated from each other. In this case, at least a part of the covering surface 68a of the side wall 65 is no longer covered by the side wall 52, and the sign portion 27 provided on the covering surface 68a is exposed to the outside. That is, the color of the appearance of the portion where the side wall 52 and the side wall 65 overlap changes from the color of the outer peripheral surface 52a to the color of the sign portion 27. Since the color of the indicator portion 27 is different from the color of the outer circumferential surface 52a, it is easy to detect the exposure of the indicator portion 27 by visual inspection. That is, the battery pack 11 of this embodiment makes it easy to detect the expansion of the battery cells 21.

[0100] The marker 27 is a reflective material attached to the covering surface 68a. Therefore, even if the battery pack 11 is placed in a dark storage chamber 76, the reflective material reflects light emitted from an external source, so that the exposed marker 27 can be easily detected by visual inspection.

[0101] The reflective material of the sign 27 diffuses and reflects light. Therefore, even if the reflective material and the worker are not directly facing each other, the light reflected by the reflective material reaches the worker, and the exposure of the sign 27 can be easily detected visually.

[0102] The battery panel 10 has multiple assembled batteries 11. Generally, inspecting the expansion of the battery cells 21 of the multiple assembled batteries 11 individually places a heavy burden on an operator. However, the assembled battery 11 of the present embodiment makes it easy to detect the expansion of the battery cells 21 by visual inspection. Therefore, the battery panel 10 of the present embodiment can easily detect the expansion of the battery cells 21 in the multiple assembled batteries 11.

[0103] The housing 12 is provided with a storage chamber 76 for storing the plurality of assembled batteries 11, and an opening 77 that communicates the storage chamber 76 with the outside. Each of the plurality of assembled batteries 11 has an end face 22a facing the opening 77, and a positive electrode terminal 25 and a negative electrode terminal 26 provided on the end face 22a. The positive electrode terminal 25 of one of the two adjacent assembled batteries 11 and the negative electrode terminal 26 of the other are electrically connected to each other. The plurality of assembled batteries 11 are arranged with a gap between them so that the covering surface 68a of one of the two adjacent assembled batteries 11 faces the other assembled battery 11. For this reason, the sign portion 27 provided on the covering surface 68a does not face a worker who visually checks the assembled batteries 11 in the storage chamber 76 through the opening 77. However, since a gap is provided between the plurality of assembled batteries 11, the worker can view the sign portion 27 exposed due to the expansion of the battery cells 21 at an angle. Therefore, the battery panel 10 of the present embodiment can easily detect the expansion of the battery cells 21 in the multiple assembled batteries 11.

[0104] The sensor 81 is attached to the cases 22 of the multiple assembled batteries 11 and detects the expansion of the cases 22 of the multiple assembled batteries 11. The determination device 83 determines whether or not one or more cases 22 of the multiple assembled batteries 11 have expanded based on an output signal from the sensor 81. The multiple assembled batteries 11 are arranged to form multiple rows L1 and L2. The case 22 of each of the multiple assembled batteries 11 has a long side 22b, a long side 22c located opposite the long side 22b, and an upper surface 22d extending between the long side 22b and the long side 22c. In each of the multiple rows L1 and L2, one long side 22b of two adjacent batteries of the multiple assembled batteries 11 faces the other long side 22c. The sensor 81 extends along the long side 22b, the long side 22c, and the upper surface 22d of each of the multiple assembled batteries 11. The sensor 81 is attached to at least one of the long side surfaces 22b and 22c of the plurality of assembled batteries 11 at a maximum displacement part PD where the displacement due to expansion of the case 22 becomes maximum.

[0105] At maximum displacement part PD, the displacement due to expansion of case 22 becomes maximum, and therefore, for example, the displacement, deformation, or distortion of case 22 can be easily detected by sensor 81. For this reason, the battery panel 10 of this embodiment can easily detect whether or not the cases 22 of multiple assembled batteries 11 have expanded using one sensor 81. Since sensor 81 is attached to case 22 so as to extend along the long side surface 22b, long side surface 22c, and top surface 22d, which are the outer surfaces of case 22, sensor 81 can be easily attached to multiple assembled batteries 11 in an existing battery panel 10.

[0106] The sensor 81 has an FPC 91 and a plurality of strain gauges 96 provided on the FPC 91 and connected in series to each other. At least one of the plurality of strain gauges 96 is attached to the maximum displacement part PD of each of the plurality of assembled batteries 11. This allows the sensor 81 to be easily attached to the case 22 so as to extend along the long side surface 22b, the long side surface 22c, and the top surface 22d. Because the plurality of strain gauges 96 are connected in series, the determination device 83 can easily detect whether one or more cases 22 of the plurality of assembled batteries 11 have expanded from the electrical resistance of the plurality of strain gauges 96.

[0107] The bridge circuit BC has resistors 105, 106, and 107 with constant electrical resistance, and a variable resistor RX. The variable resistor RX has a plurality of strain gauges 96. When one or more cases 22 of the plurality of assembled batteries 11 expand, the overall resistance of the plurality of directly connected strain gauges 96 changes. For this reason, the bridge circuit BC is a Wheatstone bridge in which the electrical resistance of the variable resistor RX varies. The determination device 83 can easily detect whether one or more cases 22 of the plurality of assembled batteries 11 have expanded, for example, based on the value of a galvanometer 108 in the bridge circuit BC.

[0108] (Modification) In the first embodiment described above, the sign portion 27 is a reflective material. However, the sign portion 27 may be a fluorescent paint applied to the covering surface 68a. In this case, even if the worker does not carry a light, for example, the worker can easily detect the exposure of the sign portion 27 by visual inspection.

[0109] The marker unit 27 is not limited to the above examples. For example, the marker unit 27 may be a colored tape attached to the covered surface 68a, or may be a white or other light-colored paint applied to the covered surface 68a. In addition, when the color of the outer peripheral surfaces 52a, 65a is a light color such as white, the marker unit 27 may be a dark color such as black. For example, a worker can easily detect the exposure of the marker unit 27 by visual inspection based on the contrast between the outer peripheral surfaces 52a, 65a and the marker unit 27.

[0110] In the above-described first embodiment, one sensor 81 is attached to the cases 22 of all the assembled batteries 11 forming the multiple rows L1 and L2. However, the measurement system 14 may have multiple sensors 81. In this case, for example, one sensor 81 is attached to the cases 22 of the multiple assembled batteries 11 forming the row L1, and another sensor 81 is attached to the cases 22 of the multiple assembled batteries 11 forming the row L2. This enables the battery panel 10 to easily detect in which of the multiple rows L1 and L2 the expansion of the assembled battery 11 has occurred.

[0111] Second embodiment The second embodiment will be described below with reference to Fig. 8. In the following description of the embodiments, components having the same functions as components already described are given the same reference numerals as the components already described, and further description may be omitted. Also, components given the same reference numerals do not necessarily have all the same functions and properties, and may have different functions and properties according to each embodiment.

[0112] 8 is an exemplary perspective view showing a battery pack 11 according to the second embodiment. As shown in FIG 8, a sensor band 85 according to the second embodiment extends along end faces 22a and long side faces 22b, 22c of each of the multiple battery packs 11.

[0113] The end surface 22a extends between an edge of the long side surface 22b in the -Y direction and an edge of the long side surface 22c in the -Y direction. Therefore, the end surface 22a is an example of a third surface in the second embodiment.

[0114] In the second embodiment, sensor band 85 extends substantially in the Y direction along upper end 56 of side wall 52 on long sides 22b, 22c. In other words, sensor band 85 does not straddle the boundary between side wall 52 and side wall 65.

[0115] In the battery panel 10 of the second embodiment described above, the sensor band 85 does not straddle the boundary between the side wall 52 and the side wall 65. Therefore, the battery pack 11 of the present embodiment can prevent the edge of the side wall 52 from damaging the sensor 81 when the case 22 expands.

[0116] (Third embodiment) The third embodiment will be described below with reference to Fig. 9. Fig. 9 is an exemplary front view showing a battery panel 10 according to the third embodiment. As shown in Fig. 9, the measurement system 14 of the third embodiment has a sensor 150 instead of the sensor 81 and the AD converter 82. The sensor 150 is a so-called optical fiber strain sensor, and has an optical fiber 151 and a measuring instrument 152.

[0117] The optical fiber 151 is provided with a plurality of interference fringes arranged at intervals in the longitudinal direction of the optical fiber 151. The intervals between the interference fringes do not have to be constant. For example, a long interval may be provided between a group of a plurality of interference fringes arranged at a constant interval and another group of interference fringes.

[0118] The optical fiber 151 is attached to the case 22 of the multiple assembled batteries 11. The optical fiber 151 extends along the long side surfaces 22b, 22c and the top surface 22d of each of the multiple assembled batteries 11. The optical fiber 151 is attached to the case 22 with a predetermined slack.

[0119] The optical fiber 151 extends in the Z direction on the long sides 22b and 22c, straddling the upper end portion 56 of the side wall 52. In other words, the optical fiber 151 extends across the boundary between the side wall 52 and the side wall 65. It is not necessary for the optical fiber 151 to straddle the boundary between the side wall 52 and the side wall 65.

[0120] The optical fiber 151 is attached to the maximum displacement part PD at the long side surfaces 22b and 22c. A plurality of interference fringes are provided in the portion of the optical fiber 151 that is attached to the maximum displacement part PD.

[0121] The optical fiber 151 is attached to the long side surfaces 22b, 22c and the top surface 22d by, for example, an adhesive tape. The optical fiber 151 may be attached to the maximum displacement part PD by an adhesive.

[0122] The measuring instrument 152 inputs light such as laser light into the optical fiber 151. The laser light is reflected in a manner different from other portions in the interference fringes of the optical fiber 151. The measuring instrument 152 receives the laser light reflected inside the optical fiber 151. The measuring instrument 152 outputs an output signal indicating, for example, the wavelength of the received laser light and the return time of the laser light to the determining device 83.

[0123] When case 22 expands, optical fiber 151 is pulled in the longitudinal direction, causing a change in the spacing between multiple interference fringes. This causes a change in the wavelength of the laser light reflected inside optical fiber 151 and the return time of the laser light, causing the output signal of measuring device 152 to also change. That is, measuring device 152 can detect the distortion of optical fiber 151 based on the light reflected inside optical fiber 151.

[0124] The determination device 83 determines whether the output signal of the measuring device 152 is outside a predetermined range. When the case 22 expands, the output signal of the measuring device 152 goes outside the range, and the determination device 83 determines that the case 22 of the assembled battery 11 has expanded. That is, the determination device 83 determines whether one or more cases 22 of the multiple assembled batteries 11 have expanded, based on the output signal of the measuring device 152 of the sensor 150. In addition, the sensor 150 detects the expansion of the cases 22 of the multiple assembled batteries 11.

[0125] In the battery panel 10 of the third embodiment described above, the sensor 150 has an optical fiber 151 and a measuring device 152. The optical fiber 151 extends along the long side surface 22b, the long side surface 22c, and the top surface 22d, and is attached to the case 22 of the multiple assembled batteries 11. The measuring device 152 inputs light to the optical fiber 151 and detects distortion of the optical fiber 151 based on the light reflected inside the optical fiber 151. The optical fiber 151 can be easily attached to the case 22 by, for example, adhesive tape. Therefore, the battery panel 10 of this embodiment can facilitate the installation of the sensor 150.

[0126] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0127] 10...battery panel, 11...battery pack, 12...housing, 21...battery cell, 22...case, 22a...end surface, 22b, 22c...long side surface, 22d...top surface, 23...bus bar, 24...monitoring board, 25...positive terminal, 26...negative terminal, 27...signal portion, 41...lower case, 42...upper case, 51...bottom wall, 52...side wall, 52a...outer peripheral surface, 65...side wall, 68a...coating surface, 76...accommodation chamber, 77...opening, 81, 150...sensor, 83...determination device, 91...flexible printed circuit board (FPC), 96...strain gauge, 105, 106, 107...resistor, 151...optical fiber, 152...measuring instrument, L1, L2...column, BC...bridge circuit, RX...variable resistor, PD...maximum displacement portion.

Claims

1. A plurality of battery cells; a plurality of bus bars, each of which electrically connects two of the plurality of battery cells; a substrate electrically connected to the plurality of battery cells via the plurality of bus bars; a lower case including a bottom wall supporting the plurality of battery cells, a first side wall protruding from the bottom wall and surrounding the plurality of battery cells, and an outer circumferential surface provided on the first side wall and facing outward, and at least partially accommodating the plurality of battery cells; an upper case that houses the substrate and has a second side wall that is surrounded by the first side wall and is attached to the first side wall by a snap fit, and a covering surface that is provided on the second side wall, faces outward, and is covered by the first side wall; A marking portion provided on the covering surface and having a color different from the color of the outer circumferential surface; A battery pack comprising:

2. The sign portion has a reflective material attached to the covering surface. The battery pack of claim 1.

3. The reflector diffusely reflects light. The battery pack of claim 2.

4. The marking portion is a fluorescent paint applied to the covering surface. The battery pack of claim 1.

5. Multiple battery packs, A battery panel comprising: Each of the plurality of assembled batteries is the assembled battery according to any one of claims 1 to 4. Battery board.

6. a housing including a chamber for accommodating the plurality of assembled batteries and an opening communicating the chamber with the outside; Further comprising: Each of the plurality of assembled batteries has an end surface facing the opening, and a positive terminal and a negative terminal provided on the end surface, the positive electrode terminal of one of two adjacent ones of the plurality of assembled batteries and the negative electrode terminal of the other adjacent one of the assembled batteries are electrically connected to each other; The plurality of assembled batteries are arranged at intervals such that the covered surface of one of two adjacent assembled batteries faces the other. The battery panel of claim 5.

7. a plurality of assembled batteries each including a plurality of battery cells and a case for housing the plurality of battery cells; a sensor attached to the cases of the plurality of assembled batteries and configured to detect expansion of the cases of the plurality of assembled batteries; a determination device that determines whether the case of one or more of the plurality of assembled batteries has expanded based on an output signal from the sensor; and Equipped with The plurality of assembled batteries are arranged to form a plurality of rows, the case of each of the plurality of assembled batteries has a first surface, a second surface opposite to the first surface, and a third surface extending between the first surface and the second surface; In each of the plurality of rows, the first surface of one of two adjacent batteries of the plurality of assembled batteries faces the second surface of the other adjacent battery, the sensor extends along the first surface, the second surface, and the third surface of each of the plurality of assembled batteries; the sensor is attached to a maximum displacement portion, at least one of the first surface and the second surface of the plurality of assembled batteries, where a displacement due to expansion of the case becomes maximum; Battery board.

8. The sensor includes a flexible printed circuit board and a plurality of strain gauges provided on the flexible printed circuit board and connected in series to each other; At least one of the plurality of strain gauges is attached to the maximum displacement portion of each of the plurality of assembled batteries. The battery panel of claim 7.

9. a bridge circuit having a first resistor having a constant electric resistance, a second resistor having a constant electric resistance, a third resistor having a constant electric resistance, and a fourth resistor; Further comprising: the fourth resistor includes the plurality of strain gauges; The battery panel of claim 8.

10. the sensor includes an optical fiber extending along the first surface, the second surface, and the third surface and attached to the case of the plurality of assembled batteries, and a measuring device that inputs light to the optical fiber and detects a distortion of the optical fiber based on the light reflected inside the optical fiber. The battery panel of claim 7.

Images