Battery unit

Abstract

To realize a battery unit capable of detecting the state of a battery with high accuracy.SOLUTION: A battery unit includes a battery body, an exterior covering the battery body and having an opening, a film layer provided between the battery body and the exterior so as to cover at least the opening, and a strain gauge attached to the surface of the film layer exposed from the opening and detecting strain in the film layer, and the exterior and the film layer have different strengths.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery unit. [Background technology]

[0002] Patent Document 1 discloses a battery pack including a battery and a sensor that detects the state of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7008618 Summary of the Invention [Problem to be solved by the invention]

[0004] As the battery life shortens, it may expand and cause leakage or fire, so there is a need for technology to more accurately detect battery expansion.

[0005] An object of the present disclosure is to realize a battery unit capable of detecting battery expansion with high accuracy. [Means for solving the problem]

[0006] The battery unit of the present disclosure includes a battery body, an exterior covering the battery body and having an opening, a film layer provided between the battery body and the exterior so as to cover at least the opening, and a strain gauge attached to the exposed surface of the film layer from the opening and detecting strain in the film layer, wherein the exterior and the film layer have different strengths. Effect of the Invention

[0007] According to the battery unit of the present disclosure, battery expansion can be detected with high accuracy. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a battery unit according to a first embodiment. [Diagram 2] 2 is an enlarged cross-sectional view illustrating the battery unit according to the first embodiment. FIG. [Diagram 3] 3 is a plan view illustrating a strain gauge mounted on the battery unit according to the first embodiment. FIG. [Figure 4] 3 is a cross-sectional view illustrating a strain gauge mounted on the battery unit according to the first embodiment. FIG. [Diagram 5] FIG. 2 is a block diagram illustrating a circuit board mounted on the battery unit according to the first embodiment. [Figure 6] 11 is a diagram illustrating a battery unit according to a second embodiment. FIG. [Figure 7] FIG. 11 is a diagram showing another example of a battery unit according to the second embodiment. [Figure 8] 13 is a diagram illustrating a battery unit according to a third embodiment. FIG. [Figure 9] 13 is a diagram illustrating a battery unit according to a fourth embodiment. FIG. [Figure 10] 13 is a diagram illustrating a battery unit according to a fifth embodiment. FIG. [Figure 11] FIG. 13 is a diagram showing another example of a battery unit according to the fifth embodiment. [Figure 12] FIG. 13 is a diagram showing another example of a battery unit according to the fifth embodiment. [Figure 13] 13A and 13B are a plan view and a cross-sectional view showing an example of a detection element included in a strain gauge according to a sixth embodiment. [Figure 14] 13A to 13C are a perspective view, a plan view, and a cross-sectional view showing an example of a detection element included in a strain gauge according to a seventh embodiment. [Figure 15] 13A to 13C are a perspective view, a plan view, and a cross-sectional view showing another example of a detection element included in a strain gauge according to the seventh embodiment. [Figure 16] 13A to 13C are a perspective view, a plan view, and a cross-sectional view showing still another example of a detection element included in a strain gauge according to the seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated explanations may be omitted.

[0010] First Embodiment FIG. 1 is a diagram showing a battery unit 1, which is an example of a battery unit according to the first embodiment. FIG. 2 is an enlarged cross-sectional view showing the battery unit 1, which is an example of a battery unit according to the first embodiment. Specifically, FIG. 2 is an enlarged cross-sectional view of the vicinity of an opening 30h of an exterior 30 in FIG. 1. The battery unit 1 is used, for example, as a battery for an electric vehicle. The battery unit 1 includes a strain gauge 10, a film layer 20, the exterior 30, and a battery body 40. The battery unit 1 also includes a pair of electrodes 70.

[0011] In the following embodiments, when describing a rectangular battery unit, the side on which electrode 70 is exposed will be referred to as the "top", the side opposite the top will be referred to as the "bottom", and the other four sides will be referred to as the "sides".

[0012] The battery unit 1 has a hexahedral rectangular shape. The exterior 30 of the battery unit 1 has an opening 30h on the upper surface.

[0013] [Strain gauge 10] The strain gauge 10 is an example of a detection unit that detects strain due to expansion of the battery main body 40 (whether or not the battery main body 40 has expanded and / or the degree of expansion). The strain gauge 10 is attached to the film layer 20. More specifically, the strain gauge 10 is attached to a portion of the film layer 20 that is exposed through the opening 30h of the exterior 30 (i.e., the exposed surface 20S). The strain gauge 10 detects strain in the film layer 20 due to the expansion of the battery main body 40, thereby detecting the presence or absence and / or the degree of expansion of the battery main body 40.

[0014] The shape and size of the strain gauge 10 are not particularly limited as long as they fit within the exposed surface 20S. In the present embodiment, the strain gauge 10 is a single gauge, but the strain gauge 10 may be a two-gauge or four-gauge strain sensor.

[0015] [Film layer 20] The film layer 20 is provided so as to cover at least the opening 30h of the exterior 30. The film layer 20 is formed, for example, from a resin. Examples of the resin forming the film layer 20 include a sealant film such as biaxially oriented nylon, CPP (non-oriented polypropylene) or PE (polyethylene), as well as a single-layer or multi-layer film such as nylon or PET (polyethylene terephthalate).

[0016] [Exterior 30] The exterior 30 is provided to cover the battery body 40. The exterior 30 is the outermost member of the battery unit 1. The exterior 30 is formed of, for example, metal or resin. The exterior 30 has an opening 30h on its upper surface.

[0017] In the battery unit 1, the strength of the film layer 20 is different from the strength of the exterior 30. For example, it is preferable that the strength of the film layer 20 is weaker than the strength of the exterior 30. By making the strength of the film layer 20 weaker than the strength of the exterior 30, the deformation of the film layer 20 due to the internal pressure from the battery body 40 can be increased. Since the deformation of the film layer 20 is detected by the strain gauge 10, it becomes possible to detect even a more minute expansion of the battery as strain. Therefore, according to the battery unit 1 of the present disclosure, the expansion of the battery can be detected with high accuracy.

[0018] The specific strength values ​​of the film layer 20 and the exterior 30 are determined appropriately depending on the application, shape, and usage environment of the battery unit 1, the location where the battery unit 1 is attached, and other factors.

[0019] [Battery body 40] The battery body 40 is, for example, a part of the battery body of a secondary battery such as a lithium ion battery. The battery body 40 may have, for example, a rectangular shape as shown in Fig. 1. The battery body 40 includes a positive electrode, a negative electrode, a separator, an electrolyte, and the like.

[0020] [Details of strain gauge 10] Next, the strain gauge 10 will be described in more detail. FIG. 3 is a plan view of the strain gauge 10 mounted on the battery unit 1, which is an example of the battery unit according to the first embodiment. FIG. 4 is a cross-sectional view of the strain gauge 10 mounted on the battery unit 1, which is an example of the battery unit according to the first embodiment. Specifically, FIG. 4 is a cross-sectional view showing a cross section along the line AA in FIG. 3. Referring to FIGS. 3 and 4, the strain gauge 10 has a substrate 11, a resistor 12, and a terminal portion 13. The strain gauge 10 can be attached to the exposed surface 20S of the film layer 20, for example, by applying an adhesive to the lower surface 11b of the substrate 11.

[0021] In the present embodiment, the strain gauge 10 is described, for convenience, as the side of the substrate 11 of the strain gauge 10 on which the resistor 12 is provided is referred to as the upper side or one side, and the side on which the resistor 12 is not provided is referred to as the lower side or the other side. Also, the side on which the resistor 12 is provided in each portion is referred to as the one side or upper side, and the side on which the resistor 12 is not provided is referred to as the other side or lower side. However, the strain gauge 10 can be used upside down or placed at any angle. Also, the planar view refers to the object being viewed from the normal direction of the upper surface 11a of the substrate 11, and the planar shape refers to the shape of the object being viewed from the normal direction of the upper surface 11a of the substrate 11.

[0022] The substrate 11 is an insulating member that serves as a base layer for forming the resistor 12 and the like, and has flexibility. The thickness of the substrate 11 is not particularly limited and can be appropriately selected depending on the purpose, but can be, for example, about 5 μm to 500 μm. In particular, it is preferable that the thickness of the substrate 11 is 5 μm to 200 μm, since it is possible to reduce the strain sensitivity error of the resistor 12.

[0023] The substrate 11 can be formed from an insulating resin film such as PI (polyimide) resin, epoxy resin, PEEK (polyether ether ketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, polyolefin resin, etc. The film refers to a flexible member having a thickness of about 500 μm or less.

[0024] Here, "formed from an insulating resin film" does not prevent the base material 11 from containing fillers, impurities, etc. in the insulating resin film. The base material 11 may be formed from an insulating resin film containing fillers such as silica or alumina.

[0025] However, if the substrate 11 does not need to be flexible, the substrate 11 may be made of materials such as SiO2, ZrO2 (including YSZ), Si, Si2N3, Al2O3 (including sapphire), ZnO, perovskite ceramics (CaTiO3, BaTiO3), etc.

[0026] The resistor 12 is a thin film formed in a predetermined pattern on the substrate 11, and is a sensing part that generates a resistance change when strained. The resistor 12 may be formed directly on the upper surface 11a of the substrate 11, or may be formed on the upper surface 11a of the substrate 11 via another layer. For convenience, the resistor 12 is shown in Fig. 3 with a matte pattern.

[0027] The resistor 12 can be formed, for example, from a material containing Cr (chromium), a material containing Ni (nickel), or a material containing both Cr and Ni. That is, the resistor 12 can be formed from a material containing at least one of Cr and Ni. An example of a material containing Cr is a Cr mixed phase film. An example of a material containing Ni is Cu-Ni (copper nickel). An example of a material containing both Cr and Ni is Ni-Cr (nickel chromium).

[0028] Here, the Cr mixed phase film is a film in which Cr, CrN, Cr2N, etc. are mixed. The Cr mixed phase film may contain inevitable impurities such as chromium oxide.

[0029] The thickness of resistor 12 is not particularly limited and can be appropriately selected depending on the purpose, and can be, for example, about 0.05 μm to 2 μm. In particular, a thickness of resistor 12 of 0.1 μm or more is preferable in that the crystallinity of the crystals constituting resistor 12 (for example, the crystallinity of α-Cr) is improved. Moreover, a thickness of resistor 12 of 1 μm or less is even more preferable in that film cracks and warping from substrate 11 caused by internal stress of the film constituting resistor 12 can be reduced.

[0030] For example, when the resistor 12 is a Cr mixed phase film, the stability of the gauge characteristics can be improved by making the resistor 12 mainly composed of α-Cr (alpha chromium), which is a stable crystal phase. In addition, by making the resistor 12 mainly composed of α-Cr, the gauge factor of the strain gauge 10 can be 10 or more, and the gauge factor temperature coefficient TCS and the resistance temperature coefficient TCR can be in the range of -1000 ppm / °C to +1000 ppm / °C. Here, the main component means that the target substance accounts for 50 mass % or more of the total substance constituting the resistor, but from the viewpoint of improving the gauge characteristics, it is preferable that the resistor 12 contains α-Cr at 80 weight % or more. Note that α-Cr is Cr with a bcc structure (body-centered cubic lattice structure).

[0031] The terminal portions 13 extend from both ends of the resistor 12 and are formed in a generally rectangular shape in plan view, wider than the resistor 12. The terminal portions 13 are a pair of electrodes for outputting to the outside a change in the resistance value of the resistor 12 caused by distortion, and are connected to, for example, a flexible board or a lead wire for external connection.

[0032] For example, the resistor 12 extends from one of the terminal portions 13 while folding back in a zigzag pattern and is connected to the other terminal portion 13. The upper surface of the terminal portion 13 may be covered with a metal having better solderability than the terminal portion 13. Although the resistor 12 and the terminal portion 13 are denoted by different reference numerals for convenience, they can be integrally formed from the same material in the same process.

[0033] A cover layer 15 (insulating resin layer) may be provided on the upper surface 11a of the base material 11 so as to cover the resistor 12 and expose the terminal portion 13. By providing the cover layer 15, mechanical damage to the resistor 12 can be prevented. Furthermore, by providing the cover layer 15, the resistor 12 can be protected from moisture and the like. The cover layer 15 may be provided so as to cover the entire portion except for the terminal portion 13.

[0034] The cover layer 15 can be formed from an insulating resin such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, or composite resin (e.g., silicone resin, polyolefin resin). The cover layer 15 may contain a filler or a pigment. There is no particular limit to the thickness of the cover layer 15 and it can be appropriately selected depending on the purpose, but it can be, for example, about 2 μm to 30 μm.

[0035] In the battery unit 1, when the battery body 40 expands, the film layer 20 correspondingly deforms. The strain gauge 10 detects the expansion of the battery body 40 (whether the battery body 40 expands and the degree of expansion) as a change in the resistance value of the resistor 12 via the film layer 20, and can output the result from the terminal portion 13 which is a pair of electrodes.

[0036] When the battery body 40 expands, the resistor 12 of the strain gauge 10 becomes thinner and longer, increasing its resistance. When the battery body 40 contracts, the resistor 12 of the strain gauge 10 becomes thicker and shorter, decreasing its resistance. Therefore, by monitoring the increase or decrease in the resistance of the resistor of the strain gauge 10, it is possible to distinguish whether the battery body 40 is expanding or contracting.

[0037] To manufacture the strain gauge 10, first, a substrate 11 is prepared, and the resistor 12 and terminal portion 13 having a planar shape as shown in Fig. 3 are formed on the upper surface 11a of the substrate 11. The material and thickness of the resistor 12 and terminal portion 13 are as described above. The resistor 12 and terminal portion 13 can be integrally formed from the same material.

[0038] The resistor 12 and the terminal portion 13 can be formed, for example, by forming a film by magnetron sputtering using a raw material capable of forming the resistor 12 and the terminal portion 13 as a target, and patterning the film by photolithography. The resistor 12 and the terminal portion 13 may be formed by reactive sputtering, vapor deposition, arc ion plating, pulsed laser deposition, or the like instead of magnetron sputtering.

[0039] From the viewpoint of stabilizing the gauge characteristics, it is preferable to vacuum-form a functional layer having a thickness of about 1 nm to 100 nm as a base layer by, for example, a conventional sputtering method on the upper surface 11a of the substrate 11 before forming the resistor 12 and the terminal portion 13. After the resistor 12 and the terminal portion 13 are formed on the entire upper surface of the functional layer, the functional layer is patterned into the planar shape shown in FIG. 3 together with the resistor 12 and the terminal portion 13 by photolithography.

[0040] In the present application, the functional layer refers to a layer having a function of promoting the crystal growth of at least the upper layer, the resistor 12. The functional layer preferably further has a function of preventing oxidation of the resistor 12 due to oxygen and moisture contained in the substrate 11, and a function of improving the adhesion between the substrate 11 and the resistor 12. The functional layer may further have other functions.

[0041] Since the insulating resin film constituting the substrate 11 contains oxygen and moisture, it is effective for the functional layer to have the function of preventing oxidation of the resistor 12, particularly when the resistor 12 contains Cr, since Cr forms a self-oxidized film.

[0042] The material of the functional layer is not particularly limited as long as it has the function of promoting the crystal growth of at least the upper layer, the resistor 12, and can be appropriately selected depending on the purpose. For example, Cr (chromium), Ti (titanium), V (vanadium), Nb (niobium), Ta (tantalum), Ni (nickel), Y (yttrium), Zr (zirconium), Hf (hafnium), Si (silicon), C (carbon), Zn (zinc), Cu (copper), Bi (bismuth), Examples of the metal include one or more metals selected from the group consisting of Fe (iron), Mo (molybdenum), W (tungsten), Ru (ruthenium), Rh (rhodium), Re (rhenium), Os (osmium), Ir (iridium), Pt (platinum), Pd (palladium), Ag (silver), Au (gold), Co (cobalt), Mn (manganese), and Al (aluminum), an alloy of any of the metals in this group, or a compound of any of the metals in this group.

[0043] Examples of the alloy include FeCr, TiAl, FeNi, NiCr, CrCu, etc. Examples of the compound include TiN, TaN, Si3N4, TiO2, Ta2O5, SiO2, etc.

[0044] The functional layer can be formed in vacuum by conventional sputtering, for example, using a raw material capable of forming the functional layer as a target and introducing Ar (argon) gas into a chamber. By using conventional sputtering, the functional layer is formed while etching the upper surface 11a of the substrate 11 with Ar, so that the amount of the functional layer formed can be minimized and the effect of improving adhesion can be obtained.

[0045] However, this is just one example of a method for forming the functional layer, and the functional layer may be formed by other methods. For example, a method may be used in which the upper surface 11a of the substrate 11 is activated by a plasma treatment using Ar or the like before forming the functional layer, thereby improving adhesion, and then the functional layer is vacuum-formed by magnetron sputtering.

[0046] There is no particular limitation on the combination of the material of the functional layer with the materials of the resistor 12 and the terminal portion 13, and it can be appropriately selected according to the purpose. For example, it is possible to use Ti for the functional layer, and form a Cr mixed phase film containing α-Cr (alpha chromium) as the main component for the resistor 12 and the terminal portion 13.

[0047] In this case, for example, the resistor 12 and the terminal portion 13 can be formed by magnetron sputtering using a raw material capable of forming a Cr mixed phase film as a target and introducing Ar gas into a chamber. Alternatively, the resistor 12 and the terminal portion 13 may be formed by reactive sputtering using pure Cr as a target and introducing an appropriate amount of nitrogen gas together with Ar gas into a chamber.

[0048] In these methods, the growth surface of the Cr mixed-phase film is determined by the functional layer made of Ti, and a Cr mixed-phase film containing α-Cr, which has a stable crystal structure, as a main component, can be formed. Furthermore, the Ti constituting the functional layer is diffused into the Cr mixed-phase film, thereby improving the gauge characteristics. For example, the gauge factor of the strain gauge 10 can be set to 10 or more, and the gauge factor temperature coefficient TCS and the resistance temperature coefficient TCR can be set within the range of −1000 ppm / ° C. to +1000 ppm / ° C. In addition, when the functional layer is formed of Ti, the Cr mixed-phase film may contain Ti and TiN (titanium nitride).

[0049] When the resistor 12 is a Cr mixed phase film, the functional layer made of Ti has all of the following functions: promoting the crystal growth of the resistor 12, preventing oxidation of the resistor 12 due to oxygen and moisture contained in the substrate 11, and improving adhesion between the substrate 11 and the resistor 12. The same applies when Ta, Si, Al, or Fe is used as the functional layer instead of Ti.

[0050] In this way, by providing a functional layer under the resistor 12, it is possible to promote crystal growth of the resistor 12, and to produce a resistor 12 consisting of a stable crystal phase. As a result, it is possible to improve the stability of the gauge characteristics of the strain gauge 10. In addition, the material constituting the functional layer diffuses into the resistor 12, thereby improving the gauge characteristics of the strain gauge 10.

[0051] After forming the resistor 12 and the terminal portion 13, a cover layer 15 that covers the resistor 12 and exposes the terminal portion 13 is provided on the upper surface 11a of the substrate 11 as necessary, thereby completing the strain gauge 10. The cover layer 15 can be produced, for example, by laminating a semi-cured thermosetting insulating resin film on the upper surface 11a of the substrate 11 so as to cover the resistor 12 and expose the terminal portion 13, and then heating and curing the film. The cover layer 15 may also be produced by applying a liquid or paste-like thermosetting insulating resin to the upper surface 11a of the substrate 11 so as to cover the resistor 12 and expose the terminal portion 13, and then heating and curing the film.

[0052] [Strain gauge 10 wiring and signal output] Fig. 5 is a block diagram illustrating a circuit board 60 to which the strain gauge 10 of the battery unit 1 is connected. Referring to Fig. 5, the strain gauge 10 (more specifically, the terminal portion 13 of the strain gauge 10) is connected to an analog front-end section 61 mounted on the circuit board 60, and the output of the analog front-end section 61 is connected to an external output terminal 62. This makes it possible to output information detected by the strain gauge 10 (information indicating the degree of expansion of the battery main body 40) from the external output terminal 62 as a digital signal.

[0053] Circuits (electronic components, etc.) having other functions may be mounted on the circuit board 60. Circuits having other functions include, for example, a voltage monitoring circuit, a protection circuit, a current detection circuit, etc. for the battery main body 40. There are no particular limitations on where the circuit board 60 is attached. For example, the circuit board 60 is attached near the battery unit 1. The circuit board 60 may be equipped with a power supply necessary for driving the circuits included in the circuit board 60, or may be supplied with electricity from a separate power supply.

[0054] The pair of terminals 13 of the strain gauge 10 are connected to the analog front end unit 61 using, for example, a flexible substrate, lead wires, or the like.

[0055] The analog front-end unit 61 includes, for example, a bridge circuit, an amplifier, an analog / digital conversion circuit (A / D conversion circuit), and an external communication function (for example, an I 2 The analog front-end unit 61 may be provided with a temperature compensation circuit. The analog front-end unit 61 may be formed as an IC or may be configured with individual components.

[0056] In the analog front-end section 61, for example, a pair of terminals 13 of the strain gauge 10 are connected to a bridge circuit. That is, one side of the bridge circuit is formed by the resistor 12 between the pair of terminals 13, and the other three sides are formed by fixed resistors. This makes it possible to obtain a voltage (analog signal) corresponding to the resistance value of the resistor 12 as the output of the bridge circuit.

[0057] The voltage output from the bridge circuit is amplified by the amplifier, and then converted into a digital signal by the A / D conversion circuit, which can be output from the external output terminal 62. If the analog front-end unit 61 includes a temperature compensation circuit, a temperature-compensated digital signal can be output from the external output terminal 62.

[0058] For example, in the battery unit 1, the battery body 40 may expand due to a decrease in the life of the battery body 40, leading to leakage of liquid, etc. In the battery unit 1, the expansion of the battery body 40 is detected by the strain gauge 10 through the film layer 20, and the detection result (information indicating the degree of expansion of the battery body 40) is output from the external output terminal 62 as a digital signal from the analog front end section 61.

[0059] For example, it is possible to connect a charging circuit to the external output terminal 62 outside the battery unit 1. In this case, the connected charging circuit can increase or decrease the charging current based on the digital signal from the analog front end section 61. Furthermore, if the connected charging circuit determines that the degree of expansion of the battery body 40 exceeds an allowable value, it can stop charging and emit an alarm or display a message such as "Charging not possible."

[0060] It is also possible to provide a control circuit including a CPU (Central Processing Unit) and the like inside the battery unit 1. The control circuit can be mounted on, for example, a circuit board 60. In this case, for example, a current cutoff switch is inserted in the line on the positive and / or negative side of the battery main body 40, and a digital signal output by the analog front-end unit 61 is input to the control circuit. When the control circuit determines, based on the digital signal from the analog front-end unit 61, that the degree of expansion of the battery main body 40 exceeds an allowable value, it can cut off the current cutoff switch to stop the operation of the battery unit 1.

[0061] In this way, by providing the strain gauge 10 in the battery unit 1, the degree of expansion of the battery body 40 can be detected as a change in the resistance value of the resistor 12. This makes it possible to control the amount of charging current or stop the operation of the battery unit 1 according to the degree of expansion of the battery body 40. As a result, when the degree of expansion of the battery body 40 exceeds an allowable value, it becomes possible to prevent forced charging or continued use, thereby preventing damage to the battery unit 1 and improving the safety of the battery unit 1.

[0062] In particular, when the resistor 12 is formed from a Cr mixed phase film, the sensitivity of the resistance value to the expansion of the battery body 40 (the amount of change in the resistance value of the resistor 12 with respect to the expansion of the same battery body 40) is significantly improved compared to when the resistor 12 is formed from Cu-Ni or Ni-Cr. When the resistor 12 is formed from a Cr mixed phase film, the sensitivity of the resistance value to the expansion of the battery body 40 is approximately 5 to 10 times higher compared to when the resistor 12 is formed from Cu-Ni or Ni-Cr. Therefore, by forming the resistor 12 from a Cr mixed phase film, it becomes possible to accurately detect the expansion of the battery body 40.

[0063] In addition, since the resistance value has a high sensitivity to the expansion of the battery body 40, it is possible to differentiate the operation to be performed depending on the degree of expansion of the battery body 40. For example, it is possible to realize a control in which a predetermined operation is performed when it is detected that the expansion of the battery body 40 is small, another operation is performed when it is detected that the expansion of the battery body 40 is medium, and yet another operation is performed when it is detected that the expansion of the battery body 40 is large.

[0064] Furthermore, if the resistance value is highly sensitive to the expansion of the battery body 40, a signal with a high S / N ratio can be obtained. Therefore, even if the number of times averaging is performed in the A / D conversion circuit of the analog front-end unit 61 is reduced, the signal can be detected with high accuracy. By reducing the number of times averaging is performed in the A / D conversion circuit, the time required for one A / D conversion can be shortened.

[0065] Moreover, when the resistor 12 is made of a Cr mixed phase film, the strain gauge 10 can be made smaller, so that it can be used in a small battery unit 1. Furthermore, since the strain gauge 10 can be made smaller, it is possible to improve the freedom of selecting the location where it is placed.

[0066] Second Embodiment In the battery unit 1 according to the first embodiment, the opening 30h of the exterior 30 is provided on the upper surface of the battery unit 1. However, the position of the opening of the exterior of the battery unit according to the present disclosure is not limited to the upper surface of the battery unit. For example, the opening 30h may be provided on the lower surface of the battery unit 1. Furthermore, the opening 30h may be provided on a side surface of the battery unit 1.

[0067] 6 is a diagram showing a battery unit 2 which is an example of a battery unit according to the second embodiment. The battery unit 2 includes a strain gauge 10, a film layer 20, an exterior 130, and a battery body 40. The exterior 130 in the battery unit 2 includes an opening 130h on a side surface. The strain gauge 10 is attached to a portion of the film layer 20 exposed from the opening 130h of the exterior 130 (i.e., the exposed surface).

[0068] Thus, except for the position of the opening 130h, the layered relationship of the strain gauge 10, the film layer 20, the exterior 130, and the battery main body 40 is the same as that of the battery unit 1. Also, like the battery unit 1, the film layer 20 and the exterior 130 have different strengths (preferably, the film layer 20 has a lower strength). With the above configuration, like the battery unit 1, the battery unit 2 can accurately detect the expansion of the battery main body 40.

[0069] 7 is a diagram showing a battery unit 3 which is another example of a battery unit according to the second embodiment. The battery unit 3 has an opening 230h in an exterior 230 on a side surface different from the side surface on which the opening 130h is provided in the battery unit 2. The strain gauge 10 is attached to a portion of the film layer 20 exposed through the opening 230h in the exterior 230 (i.e., the exposed surface). Except for the position of the opening in the exterior, the battery unit 3 is similar to the battery units 1 and 2. With the above configuration, the battery unit 3 can accurately detect the expansion of the battery main body 40, similar to the battery units 1 and 2.

[0070] Third Embodiment The battery units 1 to 3 according to the first and second embodiments are rectangular battery units, however, the shape of the battery unit according to the present disclosure is not limited to a rectangular shape.

[0071] FIG. 8 is a diagram showing a battery unit 4 which is an example of a battery unit according to the third embodiment. The battery unit 4 is a laminate type (also called a pouch type) battery unit. The battery unit 4 includes a strain gauge 10, a film layer 20, an exterior 330, and a battery body (not shown). The battery unit 4 also includes a pair of electrodes 372. One surface of the exterior 330 includes an opening 330h. The strain gauge 10 is attached to a portion of the film layer 20 exposed from the opening 330h of the exterior 330 (i.e., the exposed surface). With the above configuration, the battery unit 4 can accurately detect the expansion of the battery body 40, similar to the battery units 1 to 3.

[0072] Fourth Embodiment The exterior of the battery units according to the first to third embodiments (that is, the rectangular battery unit and the laminated battery unit) may be made up of two or more layers.

[0073] FIG. 9 is a cross-sectional view showing a battery unit 5, which is an example of a battery unit according to the fourth embodiment. The battery unit 5 includes a strain gauge 10, a film layer 20, an exterior 430, and a battery body 40. The exterior 430 has an opening 430h. The exterior 430 has a two-layer structure, for example, an inner layer 433 in contact with the battery body 40 and an outer layer 432 in contact with the outside air. More specifically, it is desirable that the thermal shrinkage rate of the inner layer 433 is greater than that of the outer layer 534. An example of a combination of materials that satisfies this condition is a case where the material of the inner layer 433 is resin and the material of the outer layer 534 is metal.

[0074] As described above, by using a material having a greater thermal shrinkage rate for layer 433 on the inside of the exterior (the side on which the battery body exists) than for layer 432 on the outside of the exterior, and manufacturing the battery unit using the following procedure, battery expansion can be detected more accurately.

[0075] First, the battery body 40 (and the electrodes 70) is covered with the exterior 430 and heated, thereby pressing the exterior 430 onto the battery body 40. At this time, since the inner layer 433 has a larger thermal shrinkage rate than the outer layer 432, the inner layer 433 comes into closer contact with the battery body 40. The black arrows in Fig. 9 indicate the pressure (hereinafter also referred to as the adhesion pressure) generated by the adhesion of the exterior 430 to the battery body 40.

[0076] When the battery body 40 of the battery unit 5 manufactured in this manner expands, an expansion pressure is generated against the exterior 430 and the film layer 20. The white arrows in FIG. 9 are an example of the expansion pressure when the battery body 40 expands. As described above, the exterior 430 is adhered to the battery body 40 during the manufacture of the battery unit 5. Therefore, as shown in FIG. 9, the adhesion pressure becomes a repulsive force against the expansion pressure. On the other hand, since the exterior 430 is not present at the opening 430h, no adhesion pressure is generated (or, even if it is generated, it is smaller than the portion where the exterior 430 is present). Therefore, the repulsive force is smaller at the opening 430h than the portion where the exterior 430 is present. Therefore, the expansion pressure of the battery body 40 in the battery unit 5 is concentrated at the opening 430h.

[0077] Furthermore, the film layer 20 disposed in the opening 430h is a member that is weaker in strength (i.e., easily distorted) than the exterior 430. Therefore, the concentrated expansion pressure distorts the film layer 20 as shown in FIG. 9, and the strain gauge 10 can detect this distortion. With the above configuration, it is possible to detect even more minute expansion of the battery body. Therefore, the expansion of the battery body 40 can be detected with higher accuracy.

[0078] Fifth embodiment The film layer and / or exterior of the battery unit according to the present disclosure may have a crease structure in which a part of the film layer and / or exterior is folded. Hereinafter, as the battery unit according to the fifth embodiment, several examples of the battery unit in which the film layer and / or exterior has the above-mentioned crease structure will be described.

[0079] FIG. 10 is an enlarged view showing a battery unit 6, which is an example of a battery unit according to the fifth embodiment. The battery unit 6 includes a film layer 120 instead of the film layer 20. Note that, in the example of FIG. 10, the exterior 130 of the battery unit 2 is taken as an example for explanation, but the configuration of the battery unit 6 other than that shown in FIG. 10 (e.g., the overall shape of the battery unit 6, the size and shape of the battery body, the materials of the exterior and the film layer, etc.) may be the same as the configuration of any of the battery units according to the first to fourth embodiments described above. In addition, the stacking relationship and strength differences between the battery body, the film layer 120, and the exterior 130 are also the same as those of the battery units 1 to 5 according to the first to fourth embodiments.

[0080] The film layer 120 has a fold structure 121 in which a part is folded over at the portion where the strain gauge 10 is attached. For example, when manufacturing the battery unit 6, the film layer 120 is folded to form the fold structure 121 and then adhered to the battery body, thereby making it possible to achieve a configuration as shown in FIG.

[0081] 10, when the battery body expands, the film layer 120 at the opening 130h is distorted more than other portions. Furthermore, in the case of the battery unit 6, since the film layer 120 has a fold structure 121, the film layer 120 is distorted more when the fold expands. This makes it possible for the strain gauge 10 to detect even more minute expansion of the battery body. Therefore, the configuration of the battery unit 6 makes it possible to detect the expansion of the battery body with greater accuracy.

[0082] 11 is an enlarged view showing a battery unit 7, which is another example of a battery unit according to the fifth embodiment. The battery unit 7 has an exterior 530 instead of the exterior 30. The exterior 530 is a film-like exterior formed of metal foil or the like. As shown in the figure, the battery unit 7 does not have a film layer. The battery unit 7 has a fold structure 531 in which part of one surface of the exterior 530 is folded over. In the battery unit 7, the strain gauge 10 detects the strain of the exterior 530.

[0083] The configuration of the battery unit 7 may be the same as that of any of the battery units of the above-described embodiments, except for the fold structure 531 of the exterior 530 and the absence of a film layer.

[0084] 11, the strain gauge 10 is directly attached to the exterior 530 having a fold structure 531. The exterior 530 has the fold structure 531 at the portion where the strain gauge 10 is attached. For example, when the battery unit 7 is manufactured, a portion of the foil portion of the exterior 530 is configured to be redundant and is crimped to the battery body so as to create wrinkles, thereby making it possible to achieve the configuration shown in FIG.

[0085] 11, when the battery body expands, the folds of the fold structure 531 of the exterior 530 widen, causing the portion of the fold structure 531 to be more distorted than other portions of the exterior 530. Therefore, by arranging a strain gauge 10 at the location of the fold structure 531, it is possible to detect the distortion of the exterior 530 caused by the expansion of the battery body.

[0086] Fig. 12 is an enlarged view showing a battery unit 8, which is another example of a battery unit according to the fifth embodiment. The battery unit 8 includes an exterior 630. Similar to the exterior 530, the exterior 630 is a film-like exterior made of metal foil or the like. The battery unit 8 also includes a film layer 220 instead of the film layer 20. Note that the configuration of the battery unit 8 other than that shown in Fig. 12 (for example, the overall shape of the battery unit 8, the size and shape of the battery body, the materials of the exterior and the film layer, etc.) may be the same as the configuration of any of the battery units according to the first to fourth embodiments described above.

[0087] The exterior 630 has an opening 630h. The battery unit 8 has the film layer 220 at the opening 630h. The layering relationship and strength differences between the film layer 220 and the exterior 630 are the same as those of the battery units 1 to 5 according to the first to fourth embodiments.

[0088] 12, in the battery unit 8, a part of the exterior 630 is woven together with a part of the film layer 220. As a result, the exterior 630 has a fold structure 631 in which a part is folded over, and the film layer 220 has a fold structure 221 in which a part is folded over.

[0089] 12, when the battery body expands, the film layer 220 at the opening 630h is distorted more than other portions. Furthermore, in the case of the battery unit 6, since both the exterior 630 and the film layer 220 have a fold structure, the strain around the arrangement position of the strain gauge 10 becomes larger as these folds widen. Therefore, it becomes possible for the strain gauge 10 to detect even more minute expansion of the battery body. Therefore, according to the configuration of the battery unit 8, the expansion of the battery body can be detected with higher accuracy.

[0090] In the above description, the battery unit is described as being rectangular and laminated, but the battery unit may be, for example, cylindrical. In the case of a cylindrical battery unit, the opening of the exterior (i.e., the location where the strain gauge 10 is attached) may be on any surface, but it is more preferable that it is on the circumferential surface of the cylinder.

[0091] In addition, in the battery units 1 to 6 and 8, the position of the opening of the exterior (i.e., the position where the strain gauge 10 is attached) is not limited to the illustrated example. Similarly, in the battery unit 7, the position where the fold structure 531 of the exterior 530 is provided (i.e., the position where the strain gauge 10 is attached) is not limited to the illustrated example.

[0092] For example, the expansion strain caused by the expansion of the battery body is larger in the center of each face of the battery unit than in the corners of each face. Therefore, if it is desired to detect the expansion strain caused by the expansion of the battery body with strain gauge 10, it is desirable to provide an opening in the exterior (or fold structure 531 of exterior 530) in the center of the face of each battery unit and place strain gauge 10 there.

[0093] Furthermore, for example, when the center of each face expands due to the expansion of the battery body, compressive strain may occur in the corners of each face of the battery unit. Therefore, if it is desired to detect this compressive strain with strain gauge 10, it is desirable to provide an opening in the exterior (or fold structure 531 of exterior 530) near the corner of each battery unit face and place strain gauge 10 there.

[0094] Sixth embodiment In the above-described embodiment and its modified example, the detection unit according to the present disclosure is a strain gauge using a resistor. That is, in the above-described embodiment, the detection unit according to the present disclosure is an electric resistance type metal strain gauge. However, the detection unit according to the present disclosure is not limited to a metal strain gauge. For example, the detection unit according to the present disclosure may be a strain gauge that detects magnetic changes caused by strain of a film layer or an exterior by a detection element included in the strain gauge.

[0095] Specifically, the detection unit according to the present disclosure may be a strain gauge including a detection element that utilizes the Villari phenomenon (described later). Also, the detection unit according to the present disclosure may be a strain gauge including a detection element having a magnetic tunnel junction (described later) structure. In the sixth embodiment, a strain gauge including a detection element that utilizes the Villari phenomenon will be described below. In the seventh embodiment, a strain gauge including a detection element having a magnetic tunnel junction structure will be described.

[0096] In each embodiment of this specification, members having similar functions are given similar names and numbers, and descriptions will not be repeated. The directions of the x-axis, y-axis, and z-axis in each drawing from FIG. 13 onwards are the same as the directions of the x-axis, y-axis, and z-axis shown in FIG. 13. In the following description, the positive direction of the z-axis is referred to as "upper", and the negative direction of the z-axis is referred to as "lower". That is, in the following description, "upper side" refers to the positive side of the z-axis, and "upper surface" refers to the surface on the positive side of the z-axis. In addition, "lower side" refers to the negative side of the z-axis, and "lower surface" refers to the surface on the negative side of the z-axis.

[0097] FIG. 13 is a diagram showing an example of a detection element 300 included in a strain gauge according to the sixth embodiment. FIG. 13(a) is a plan view of the detection element 300 when viewed from the positive to negative direction of the z axis (i.e., from the top to the bottom). FIG. 13(b) shows a cross-sectional view of the detection element 300 shown in FIG. 13(a) along line α-α'. Note that, in FIG. 13(a) and (b), wiring extending from the detection element 300 is not shown. However, the detection element 300 may be connected to wiring connecting a drive coil 320 and a power source, which will be described later, and wiring for transmitting a current detected by a sensing coil 380.

[0098] As shown in FIG. 13(a), the detection element 300 includes a driving coil 320, a sensing coil 380, and a base layer 310. The base layer 310 is a layer that serves as a core material for the driving coil 320 and the sensing coil 380. The sensing coil 380 is a coil for detecting the intensity of magnetization of the base layer 310 (more precisely, a base metal 370 described later). The driving coil 320 is a coil for generating a magnetic field. The detection element 300 has a double structure in which the sensing coil 380 is wound on the inside and the driving coil 320 is wound on the outside, with the base layer 310 as the core material. The materials for the driving coil 320 and the sensing coil 380 are preferably conductive metals such as Cu, Ag, Al, and Au, and alloys of these metals. The number of turns and the size of the cross-sectional area of ​​the driving coil 320 and the sensing coil 380 may be appropriately designed according to the strain detection sensitivity required for the detection element 300.

[0099] As will be described in detail later, when stress is applied to the base layer 310, the strength of magnetization of a base metal 370 (described later) included in the base layer 310 changes. The detection element 300 can determine the strength of the stress applied to the base layer 310 (i.e., the degree of strain) by detecting this change in the strength of magnetization with the sensing coil 380.

[0100] The configuration of the detection element 300 will be further described with reference to the cross-sectional view of Fig. 13(b). In Fig. 13(b), the driving coil 320, the sensing coil 380, and the three insulating layers 340, 350, and 360 are each formed to surround the base metal 370, which is the core material. That is, the layers with the same component number in Fig. 13(b) are connected to surround the base metal 370.

[0101] The base metal 370 is a member that serves as a core material for various coils and insulating layers. The base metal 370 may be, for example, a substantially flat metal plate. The base metal 370 is covered so as to be surrounded by the insulating layer 360. The base metal 370 is desirably made of a soft magnetic material, for example, an Fe-Si-Al based alloy such as sendust, and an Ni-Fe based alloy such as permalloy. The aforementioned base layer 310 is made of the base metal 370 and the insulating layer 360, as shown in FIG. 13(b).

[0102] An insulating layer 350 is formed outside the insulating layer 360 so as to surround the insulating layer 360 . An insulating layer 340 is further formed outside the insulating layer 350 . The insulating layer 350 is a layer that includes the sensing coil 380 and is a layer in which the gap between the sensing coil 380 is filled with an insulating material. The insulating layer 340 is a layer that includes the driving coil 320, and is a layer in which the gap between the driving coil 320 is filled with an insulating material. The insulating layers 340, 350, and 360 are desirably made of a resist cured product such as a dry film or photosensitive polyimide that does not affect magnetic fields.

[0103] One surface of the detection element 300 may be attached to the substrate 110 as shown in FIG. 13(b). The substrate 110 is a member for fixing the detection element 300. The substrate 110 may have the same configuration as the substrate 11 described in the first embodiment. For example, the substrate 110 may be a flexible substrate made of a plastic film or the like. The substrate 110 may be the same as the substrate 11 described in each of the above embodiments. The detection element 300 is attached to the film layer of the opening of the exterior (however, in the case of the battery unit 7, the exterior) via the substrate 110. The detection element 300 may be a flat or thin-film detection element as a whole. When the detection element 300 is flat or thin-film, the detection element 300 can be attached to the substrate 110 more easily. The substrate 110 is not an essential component of the detection element 300. For example, the detection element 300 may be used by directly attaching the lower surface of the detection element 300 to the film layer or the exterior without providing the substrate 110.

[0104] The film layer or exterior of this embodiment may basically have the same structure and material as the film layer and exterior of each of the previous embodiments, however, in this embodiment, it is more preferable that the film layer and exterior are made of a non-magnetic material.

[0105] Next, the principle of detecting strain using the detection element 300 will be outlined. The detection element 300 includes a base metal 370, which is a magnetic material. When an alternating current is supplied from a power source to the driving coil 320, the driving coil 320 generates an alternating magnetic field around it. This generates a magnetic field, and the base metal 370 is magnetized. When the battery body expands in this state, strain is generated in the exterior and film layer. The strain is transmitted through the substrate 110, and stress is applied to the base metal 370. Note that when the detection element 300 is attached to the film layer or exterior without the substrate 110, the stress is transmitted directly from the film layer or exterior to the base metal 370 (and the insulating layers 340 to 360 that cover it).

[0106] When stress is applied to the base metal 370, the magnetic permeability of the base metal 370 changes according to the stress. Therefore, the strength of magnetization (degree of magnetization) of the base metal 370 changes. The phenomenon in which the magnetic permeability and strength of magnetization of a magnetic body change when stress is applied to the magnetic body is called the "Villari phenomenon". According to the configuration of the detection element 300, an AC voltage corresponding to the strength of magnetization of the base metal 370 is induced in the sensing coil 380, which is a pickup coil. Therefore, based on the principle of the Villari phenomenon, the stress applied to the base metal 370 can be calculated from the value of this AC voltage. Then, the degree of strain of the film layer or the exterior can be specified from the calculated stress. Note that when the detection element 300 has the shape shown in (a) and (b) of FIG. 13, the grid direction of the detection element 300 is equal to the α-α' direction in (a) of FIG. 13. Based on the principle described above, the detection element 300 can detect the strain of the film layer or the exterior. That is, the sensing element 300 functions as a sensing element of a strain gauge.

[0107] It is desirable that the driving coil 320 is wound as uniformly as possible around the outside of the sensing coil 380 and over the entire area in which the sensing coil 380 exists. This allows an alternating magnetic field to be applied more uniformly to the entire area of ​​the base metal 370 in which the sensing coil 380 exists. This allows the change in the strength of magnetization of the base metal 370 due to the Villari phenomenon to be detected more precisely. This improves the performance of the detection element 300.

[0108] Furthermore, the insulating layer 360 may be formed on only a part of the base metal 370 rather than on the entirety of the base metal 370. For example, the region of the base metal 370 around which the sensing coil 380 and the driving coil 320 are wound may be covered with the insulating layer 360, the insulating layer 360 may be covered with the insulating layer 350 including the sensing coil 380, and the insulating layer 350 may be further covered with the insulating layer 340 including the driving coil 320.

[0109] In addition, when the base metal 370 is substantially flat, the insulating layer 360 may be formed to surround only the base metal 370 in the winding direction of the coil. That is, in (b) of FIG. 13, both ends of the base metal 370 in the x direction do not need to be covered with the insulating layer 360.

[0110] In the battery unit according to this embodiment, when strain occurs in the film layer and / or the exterior, the substrate 110 of the strain gauge (or the detection element 300 itself) is strained. The detection element 300 can detect the magnetic change caused by this strain based on the principle of the Villari phenomenon described above.

[0111] The strain gauge including the detection element 300 according to this embodiment can be arranged on the film layer (or exterior) in any arrangement pattern shown in each of the above-mentioned embodiments. That is, the detection element 300 according to this embodiment can be used to detect the strain of the film layer (or exterior) in the same way as when an electrical resistance type strain gauge is used. Therefore, the battery unit according to this embodiment has the same effects as the battery units according to the above-mentioned embodiments.

[0112] Seventh embodiment FIG. 14 is a diagram showing a detection element 500, which is an example of a detection element included in the strain gauge according to the seventh embodiment. FIG. 15 is a diagram showing a detection element 600, which is another example of the detection element according to the seventh embodiment. FIG. 16 is a diagram showing a detection element 700, which is yet another example of the detection element according to the seventh embodiment. (a) of FIG. 14 to FIG. 16 is a perspective view of the detection elements 500, 600, and 700, respectively. (b) of FIG. 14 to FIG. 16 is a plan view of the detection elements 500, 600, and 700, respectively, when viewed from the positive direction to the negative direction of the z axis. (c) of FIG. 14 to FIG. 16 is a cross-sectional view of the detection elements 500, 600, and 700 on a surface parallel to the zx plane. Note that in any of FIG. 14 to FIG. 16, wiring extending from the detection elements is not shown. However, these detection elements 500, 600, and 700 may be connected to a wiring that connects the upstream electrode 510 to a power source, and a wiring that connects the downstream electrode 520 to a power source, which will be described later.

[0113] 14 to 16(a), the detection elements 500, 600, and 700 include an upstream electrode 510, a downstream electrode 520, a magnetic film 550, and an insulating film 540. The insulating film 540 is sandwiched between the magnetic films 550 as shown in the figures. A magnetic tunnel junction is formed by the magnetic film 550 and the insulating film 540. That is, the detection elements 500, 600, and 700 have a structure in which electrodes are connected to a magnetic tunnel junction structure.

[0114] The lower surfaces of the detection elements 500, 600, and 700 may be attached to a substrate similar to the substrate 110 according to the sixth embodiment. The detection element 500 may be attached to a film layer or exterior via the substrate. The detection elements 500, 600, and 700 may be flat or thin-film detection elements as a whole. When the detection elements 500, 600, and 700 are flat or thin-film, the detection elements 500, 600, and 700 can be attached to the substrate (or the film layer or exterior) more easily. For example, the lower surfaces of the detection elements 500, 600, and 700 may be directly attached to the film layer or exterior for use.

[0115] The magnetic film 550 is a magnetic nano-thin film. The insulating film 540 is a nano-thin film of an insulator. As long as a magnetic tunnel junction structure can be formed, the materials of the magnetic film 550 and the insulating film 540 are not particularly limited. For example, the magnetic film 550 can be made of cobalt iron boron, or a 3d transition metal ferromagnetic material such as Fe, Co, or Ni, or an alloy containing these. The insulating film 540 can be made of silicon oxide, silicon nitride, aluminum oxide, magnesium oxide, or the like.

[0116] The upstream electrode 510 and the downstream electrode 520 are electrodes for applying a voltage to the magnetic tunnel junction structure. In the examples of Figs. 14 to 16, a current flows from the upstream electrode 510 to the downstream electrode 520. For example, in the case of Fig. 14(c), when a voltage is applied between the upstream electrode 510 and the downstream electrode 520, electrons flow from the upper magnetic film 550 (the positive z-axis side) over the insulating film 540 to the lower magnetic film 550 (the negative z-axis side). This is a phenomenon called the "tunnel effect", and the electrical resistance when electrons pass through the insulating film 540 is called the "tunnel resistance". In the examples of Figs. 14 to 16, the junctions of the electrodes are structured such that the ends are processed so that no current flows that short-circuits the magnetic tunnel junction structure.

[0117] However, when strain is applied to the detection element 500 through the substrate 110 or the like, a magnetic change occurs in the tunnel junction structure. More specifically, the magnetization directions of the upper and lower magnetic films 550 are shifted. When the magnetization directions of the upper and lower magnetic films 550 are shifted in this way, the tunnel resistance becomes larger than when the magnetization directions are parallel (tunnel magnetoresistance effect). Therefore, in the detection element 500 having the above-mentioned configuration, the current flowing between the electrodes becomes smaller according to the magnitude of the strain of the detection element 500 (more precisely, the magnetic tunnel junction part). That is, as the strain increases, the electric resistance increases. In this way, the detection element 500 can detect the strain based on the current value for the applied voltage. Therefore, by attaching the detection element 500 to a film layer or exterior, the strain occurring in the film layer or exterior can be measured.

[0118] The detection element having the magnetic tunnel junction structure is not limited to the example shown in FIG. 14. For example, detection elements 600 and 700 as shown in FIG. 15 and FIG. 16 can be adopted. The detection element 600 shown in FIG. 15 and the detection element 700 shown in FIG. 16 are both configured with an upstream electrode 510, a downstream electrode 520, a magnetic film 550, and an insulating film 540, and the principle of detecting strain by these configurations is the same as that of the detection element 500. The basic operation of the detection elements 600 and 700 is also the same as that of the detection element 500. The grid directions of the detection elements 500, 600, and 700 correspond to the x-axis direction (the positive direction of the x-axis and the negative direction of the x-axis) in FIG. 14 to FIG. 16, respectively. As shown in the figure, the detection element 600 shown in FIG. 15 has a structure in which the upper magnetic film 550 and the lower magnetic film 550 are partially connected. That is, a magnetic tunnel junction structure is formed only in a partial region of the magnetic film 550, and a tunnel magnetoresistance effect occurs in this structure. Meanwhile, the detection element 700 shown in Fig. 16 is attached to the base material 110 via a substrate 710. As shown in Figs. 14 to 16, the design of the detection element may be appropriately changed according to the required size, durability, magnitude of the stress to be detected, and the like, as long as it does not exceed the above-mentioned principle.

[0119] The film layer and exterior according to this embodiment may basically have the same configuration and material as the film layer and exterior according to each of the above-mentioned embodiments. However, in this embodiment, it is more preferable that the film layer and exterior are made of a non-magnetic material. For example, the exterior according to this embodiment may be made of non-magnetic stainless steel. In addition, the detection elements 500, 600, and 700 may have a substantially flat shape such as a film type as the whole element. This allows the detection element 500 to be easily attached to the film layer and exterior. In addition, the detection elements 500, 600, and 700 may have a structure for applying a weak magnetic field to the structural part of the magnetic tunnel junction, such as the drive coil. By applying a magnetic field to the structural part of the magnetic tunnel junction, the tunnel magnetoresistance effect described above can be measured more stably, and therefore the strain can be detected stably.

[0120] In addition, the "upstream electrode" and the "downstream electrode" in the detection elements 500, 600, and 700 are names for convenience, and the direction of current flow may be reversed. That is, the detection elements 500, 600, and 700 shown in Figs. 14 to 16 may be designed so that the current flows from the downstream electrode 520 to the upstream electrode 510.

[0121] In the battery unit according to this embodiment, when strain occurs in the film layer and / or the exterior, the substrate of the strain gauge (or the sensing element 500, 600, or 700 itself) is strained. The sensing element 500, 600, or 700 can detect the magnetic change caused by this strain based on the principle of the tunnel magnetoresistance effect described above.

[0122] The strain gauges including the detection elements 500, 600, and 700 according to the present embodiment can be arranged on the film layer (or exterior) in any arrangement pattern shown in each of the above-mentioned embodiments. That is, the detection elements 500, 600, and 700 according to the present embodiment can be used to detect the strain of the film layer (or exterior) in the same manner as when an electrical resistance type strain gauge is used. Therefore, the battery unit according to the present embodiment has the same effects as the battery units according to the above-mentioned embodiments.

[0123] Eighth embodiment The detection unit according to the present disclosure may be a semiconductor strain gauge, a capacitance pressure sensor, or an optical fiber strain gauge. The detection unit according to the present disclosure may also be a mechanical pressure sensor, a vibration pressure sensor, or a piezoelectric pressure sensor. The principles of various strain gauges and pressure sensors are described below.

[0124] (Semiconductor type strain gauge) A semiconductor strain gauge is a strain gauge that detects strain by utilizing the piezo-resistance effect of a semiconductor, that is, a semiconductor is used as a strain detection element.

[0125] It is known that when stress is applied to a semiconductor, strain is generated in the semiconductor's crystal lattice, causing changes in the number and mobility of carriers in the semiconductor, resulting in a change in electrical resistance. Like electrical resistance-type metal strain gauges, semiconductor-type strain gauges can be used by attaching them directly to a film layer or exterior. In this case, when the film layer or exterior expands or contracts, the attached semiconductor (more specifically, the semiconductor's crystal lattice) is strained, causing a change in electrical resistance. Therefore, the amount of strain in the film layer or exterior can be determined by measuring the electrical resistance.

[0126] The semiconductor strain gauge can also be configured as a strain sensor with a diaphragm structure. In this case, the strain sensor has, for example, a non-metallic diaphragm (or a metal diaphragm with an electrically insulating layer formed thereon) and a semiconductor (for example, a silicon thin film semiconductor) formed on the diaphragm. In such a structure including a diaphragm, when the diaphragm is distorted by a normal stress applied to the diaphragm, the electrical resistance of the semiconductor changes. Therefore, the amount of strain of the diaphragm (and thus the amount of strain of the film layer or exterior) can be determined by measuring the electrical resistance.

[0127] (Capacitive pressure sensor) A capacitance type pressure sensor is a pressure sensor that measures the pressure applied to a diaphragm as a change in the capacitance of a pair of electrodes. That is, a capacitance type pressure sensor is a pressure sensor that uses a pair of electrodes as a detection element. A capacitance type pressure sensor includes, for example, a diaphragm as a movable electrode and one or more fixed electrodes. The diaphragm is formed of, for example, silicon containing impurities (i.e., silicon that functions as a conductor).

[0128] When pressure is applied to the diaphragm, the diaphragm is displaced, and the distance between the fixed electrode and the movable electrode changes. It is known that the capacitance between the electrodes is determined according to the distance between the electrodes, provided that the dielectric constant of the interelectrode medium and the area of ​​the electrodes are constant. Therefore, the amount of displacement of the diaphragm (i.e., the magnitude of the pressure) can be determined by measuring the capacitance.

[0129] (Optical fiber strain gauge) An optical fiber strain gauge is a strain gauge that detects strain using an optical fiber on which a fiber Bragg grating (FBG) is formed. In other words, an optical fiber strain gauge is a strain gauge that uses an optical fiber as a strain detection element. An FBG is a diffraction grating that reflects light differently from other parts of the optical fiber, and each grating is formed at a fixed interval. When an optical fiber is distorted and stretched, the lattice interval of the FBG widens, and the wavelength of the reflected light of light (e.g., laser light) that is incident on the optical fiber changes. When an optical fiber is distorted and contracted, the lattice interval of the FBG narrows, and the wavelength of the reflected light of light (e.g., laser light) that is incident on the fiber changes.

[0130] By attaching an optical fiber having such characteristics to a film layer or exterior and measuring the wavelength spectrum of the reflected light of the optical fiber, the amount of strain in the optical fiber (i.e., the amount of strain in the film layer or exterior) can be determined. Note that the optical fiber type strain gauge may be a strain gauge that determines the amount of strain in the optical fiber from the change in frequency of the Brillouin scattered light generated in the optical fiber.

[0131] (Mechanical pressure sensor) A mechanical pressure sensor is a sensor that measures the amount of displacement of a mechanical structure to determine the pressure applied to the structure. A mechanical pressure sensor includes, for example, a spring or a bent tube, and measures the amount of expansion and contraction of the spring or the amount of expansion and contraction of the bent tube. These amounts of expansion and contraction (i.e., the amount of displacement) change depending on the magnitude of pressure applied to the spring or bent tube. Therefore, by measuring the amount of expansion and contraction, it is possible to determine the pressure applied to the spring or bent tube. The shape and size of the spring or bent tube may be determined appropriately depending on the size and shape of the object to which the mechanical pressure sensor is attached.

[0132] (Vibration pressure sensor) A vibration pressure sensor is a sensor that detects pressure by utilizing the phenomenon that the natural frequency of an elastic beam changes depending on the pressure (i.e., axial force) generated along the axis of the elastic beam. A vibration pressure sensor can be used by directly attaching it to a film layer or exterior, similar to an electrical resistance type metal strain gauge. For example, a vibration pressure sensor may be a pressure sensor composed of a diaphragm formed on a substrate and a beam-shaped vibrator formed on the surface of the diaphragm.

[0133] In either case, when the film layer or the exterior is distorted, the pressure is transferred directly or indirectly to the vibrator, generating an axial force in the vibrator. The natural frequency of the vibrator changes according to the axial force. Therefore, by measuring the natural frequency of the vibrator, it is possible to determine the magnitude of the pressure on the film layer or exterior caused by the expansion of the battery.

[0134] (Piezoelectric pressure sensor) A piezoelectric pressure sensor is a sensor that contains a piezoelectric element (also called a piezo element) and detects pressure using the characteristics of this piezoelectric element. When a force is applied to a piezoelectric element and it deforms (strains), it generates an electromotive force according to that force. In addition, when a voltage is applied to a piezoelectric element, it expands and contracts, generating a force according to that voltage.

[0135] A piezoelectric pressure sensor can determine the force applied to the piezoelectric element (i.e., the amount of strain of the piezoelectric element) by measuring the electromotive force of the piezoelectric element. Therefore, by attaching a piezoelectric pressure sensor to a film layer or exterior, the amount of strain of the film layer or exterior can be determined.

[0136] As described above, even if a semiconductor strain gauge, a capacitance pressure sensor, an optical fiber strain gauge, a mechanical pressure sensor, a vibration pressure sensor, or a piezoelectric pressure sensor is used in a battery unit, the same effects as those of the battery units according to the above-mentioned embodiments can be obtained.

[0137] The preferred embodiments and the like have been described above in detail. However, the battery unit according to the present disclosure is not limited to the above-described embodiments and modifications. For example, various modifications and substitutions can be made to the battery unit according to the above-described embodiments and the like without departing from the scope of the claims. [Explanation of symbols]

[0138] 1, 2, 3, 4, 5, 6, 7, 8 battery unit, 10 strain gauge, 12 resistor, 20, 120, 220 film layer, 20S exposed surface, 30, 130, 230, 330, 430, 530, 630 exterior, 30h, 131h, 230h, 330h, 430h, 630h opening, 40 battery body, 121, 221, 531, 631 fold structure, 432 outer layer, 433 inner layer, 500, 600, 700 detection element, 540 insulating film, 550 magnetic film

Claims

1. The battery itself, An outer casing that covers the battery body and has an opening, A film layer is provided between the battery body and the outer casing so as to cover at least the opening, The system includes a strain gauge attached to the exposed surface of the film layer from the opening, which detects the strain of the film layer, A battery unit in which the outer casing and the film layer have different strengths.

2. The battery unit according to claim 1, wherein at least on the exposed surface, the film layer has a folded structure in which a portion is folded.

3. The exterior is a laminated film, The battery unit according to claim 1 or 2, wherein the layer of the laminated film in contact with the battery body has a lower thermal shrinkage rate than the other layers.

4. The battery itself, A film-like outer casing that covers the battery body, The system includes a strain gauge attached to the surface of the exterior for detecting the strain of the exterior, The battery unit has a folded structure in which a portion of the exterior to which the strain gauge is attached is partially folded.

5. The strain gauge mentioned above is Insulating layer and, A functional layer formed directly on one surface of the insulating layer from a metal, alloy, or metal compound, On one side of the functional layer, Cr, CrN, and Cr ２ A resistor formed from a film containing N, The state of the battery body is detected as a change in the resistance value of the resistor, The resistor mainly consists of α-Cr, The functional layer has the function of promoting the crystal growth of α-Cr and forming a film mainly composed of α-Cr. A battery unit according to any one of claims 1, 2, and 4.

6. The resistor contains 80% by weight or more of α-Cr. The battery unit according to claim 5.

7. The battery itself, An outer casing that covers the battery body and has an opening, A film layer is provided between the battery body and the outer casing so as to cover at least the opening, The film layer includes a detection unit attached to the exposed surface of the film layer from the opening, which detects the strain of the film layer, A battery unit in which the outer casing and the film layer have different strengths.

8. The battery itself, A film-like outer casing that covers the battery body, It includes a detection unit that is attached to the surface of the exterior and detects the strain of the exterior, The battery unit has a folded structure in which a portion of the exterior to which the detection unit is attached is partially folded.

9. The battery unit according to claim 7 or 8, wherein the detection unit has a detection element that detects the magnetic change caused by the strain.

10. The aforementioned detection element includes a magnetic material, The battery unit according to claim 9, wherein the detection element is a detection element that detects a change in the magnetization strength of the magnetic material when pressure is applied to the magnetic material due to the strain.

11. The detection element includes a magnetic tunnel junction structure in which an insulating film is sandwiched between magnetic films. The battery unit according to claim 9, wherein the detection element is a detection element that detects a magnetic change generated in the structure due to the expansion of the battery body.

12. The battery unit according to claim 7 or 8, wherein the detection unit is a semiconductor strain gauge.

13. The battery unit according to claim 7 or 8, wherein the detection unit is a capacitive pressure sensor.

14. The battery unit according to claim 7 or 8, wherein the detection unit is an optical fiber strain gauge.

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