Battery unit

Abstract

To downsize a battery unit by attaching strain gauges to multiple battery cells.SOLUTION: A battery unit includes a plurality of battery cells and a strain gauge affixed to the outer peripheral surface of each of the battery cells, and each of the strain gauges has a pair of electrodes electrically connected to a sensing portion, and one of the electrodes of the strain gauges affixed to adjacent battery cells is joined via a conductive joint, and all of the strain gauges are connected in series.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In battery units used in mobile devices and the like, the battery may expand due to a decrease in the battery life in the battery unit, leading to leakage, etc. Therefore, it is important to detect battery expansion in the battery unit, and various devices for detecting battery expansion have been proposed.

[0003] One example is a device that detects the internal pressure using a strain gauge placed in the inner space of a lithium secondary battery and displays the detected internal pressure on a display. This device can determine whether the lithium secondary battery is normal or abnormal by monitoring the displayed internal pressure (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-289265 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a battery unit, it is conceivable to connect multiple battery cells in parallel and / or series and attach a strain gauge to each battery cell. In this case, there is a concern that the battery unit will become larger due to wiring connected to the strain gauge.

[0006] The present invention has been made in consideration of the above-mentioned points, and has an object to reduce the size of a battery unit in which strain gauges are affixed to a plurality of battery cells. [Means for solving the problem]

[0007] This battery unit has a plurality of battery cells and a strain gauge affixed to the outer peripheral surface of each of the battery cells, and each of the strain gauges has a pair of electrodes electrically connected to a sensing part, and one of the electrodes of the strain gauges affixed to adjacent battery cells is joined via a conductive joint, and all of the strain gauges are connected in series. Effect of the Invention

[0008] According to the disclosed technology, it is possible to realize a miniaturized battery unit in which strain gauges are attached to multiple battery cells. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view illustrating a battery unit according to a first embodiment; [Diagram 2] FIG. 2 is a diagram illustrating a battery unit according to the first embodiment. [Diagram 3] FIG. 2 is a plan view illustrating the strain gauge according to the first embodiment. [Figure 4] 1 is a cross-sectional view (part 1) illustrating a strain gauge according to a first embodiment. FIG. [Diagram 5] 4 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. FIG. [Figure 6] 10 is a diagram illustrating a battery unit according to a first modified example of the first embodiment. FIG. [Figure 7] 11 is a diagram illustrating a battery unit according to a second modified example of the first embodiment. FIG. [Figure 8] 11 is a schematic diagram illustrating a battery unit according to a second embodiment. FIG. [Figure 9] 13 is a schematic diagram illustrating a battery unit according to a first modified example of the second embodiment. FIG. [Figure 10] FIG. 4 is a diagram illustrating an example of an abnormality determination unit. [Figure 11] FIG. 2 is an example of a hardware block diagram of a control unit. [Figure 12] FIG. 13 is a plan view illustrating a label-integrated strain gauge. [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 third 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 fourth 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 a fourth 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 a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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.

[0011] First embodiment Fig. 1 is a perspective view illustrating a battery unit according to the first embodiment. Fig. 2 is a view illustrating the battery unit according to the first embodiment, in which the battery unit 1 is viewed from the direction of an arrow S in Fig. 1.

[0012] 1 and 2, the battery unit 1 has a battery cell 10, a battery cell 20, and a strain gauge 100. Although not shown, the battery cell 10 and the battery cell 20 are connected in parallel or in series. The battery unit 1 can be used, for example, by being fixed to a housing (not shown). The battery cells 10 and 20 are, for example, lithium ion batteries. The battery unit 1 can be used, for example, to supply power to an electric vehicle. The battery unit 1 may be used in various electronic devices and mobile terminals such as personal computers and smartphones.

[0013] The battery cell 10 is cylindrical and has an end face 10a, an end face 10b, and an outer peripheral face 10c. The end face 10a and the end face 10b are, for example, circular and have substantially the same area. The end face 10a and the end face 10b are, for example, parallel to each other. The outer peripheral face 10c connects the outer edge of the end face 10a to the outer edge of the end face 10b. The end face 10a and / or 10b may have a protrusion, a recess, or the like.

[0014] The battery cell 20 is cylindrical and has an end surface 20a, an end surface 20b, and an outer peripheral surface 20c. The end surface 20a and the end surface 20b are, for example, circular with approximately the same area. The end surface 20a and the end surface 20b are, for example, parallel to each other. The outer peripheral surface 20c connects the outer edge of the end surface 20a to the outer edge of the end surface 20b. The end surface 20a and / or 20b may have a protrusion, a recess, or the like. The battery cell 20 may have the same shape as the battery cell 10.

[0015] The strain gauge 100 is a sensor that detects the presence or absence of expansion or contraction of the battery cells 10 and 20 and the degree of the expansion or contraction, and is attached, for example, to the outer peripheral surface 10c of the battery cell 10 and the outer peripheral surface 20c of the battery cell 20. The strain gauge 100 is an example of a detection unit in the present disclosure. The strain gauge 100 includes a substrate 110, a resistor 130 formed on the substrate 110, wiring 140, and a pair of electrodes 150. Details of the strain gauge 100 will be described later.

[0016] The strain gauge 100 may be attached to a part of or the entire outer circumferential surface 10c of the battery cell 10 and the outer circumferential surface 20c of the battery cell 20. For example, by extending the range in which the resistor 130 of the strain gauge 100 is arranged in the axial direction of the battery cells 10 and 20, the strain gauge 100 can be attached to the entire outer circumferential surface 10c of the battery cell 10 and the outer circumferential surface 20c of the battery cell 20.

[0017] One electrode 150 of the strain gauge 100 affixed to the outer peripheral surface 10c of the battery cell 10 and one electrode 150 of the strain gauge 100 affixed to the outer peripheral surface 20c of the battery cell 20 are joined via a conductive joint 200. As a result, the strain gauge 100 affixed to the outer peripheral surface 10c of the battery cell 10 and the strain gauge 100 affixed to the outer peripheral surface 20c of the battery cell 20 are connected in series.

[0018] The joint 200 directly joins the opposing surfaces of the electrodes 150 of the strain gauges 100 attached to adjacent battery cells. The joint 200 can be made of any conductive bonding material, such as solder such as tin-silver-copper or tin-copper-nickel, or conductive paste such as silver paste or copper paste.

[0019] 1 and 2 show an example in which the battery unit 1 has two battery cells, but the battery unit 1 may have three or more battery cells. In that case, too, the strain gauges 100 are attached to the outer peripheral surface of each battery cell, and one electrode 150 of the strain gauges 100 attached to adjacent battery cells is joined to each other via a conductive joint 200, and all the strain gauges 100 are connected in series.

[0020] With this configuration, information on the expansion or contraction of any one or more of the battery cells can be obtained based on the output of the strain gauges 100 connected in series. That is, when any one or more of the battery cells expands, the resistance value of the strain gauges 100 connected in series increases. By monitoring this resistance value, information on the expansion of any one or more of the battery cells can be obtained. Also, when any one or more of the battery cells contracts, the resistance value of the strain gauges 100 connected in series decreases. By monitoring this resistance value, information on the contraction of any one or more of the battery cells can be obtained. Also, the degree of expansion or contraction can be detected based on the degree of change in the resistance value of the output of the strain gauges 100 connected in series.

[0021] In addition, in the battery unit 1, one side electrodes 150 of the strain gauges 100 attached to adjacent battery cells are directly joined to each other via the conductive joint 200, so there is no need for wiring to connect the electrodes 150 to each other. This makes it unnecessary to secure a space that was previously required when connecting one side electrodes 150 of the strain gauges 100 to each other via wiring in adjacent battery cells. As a result, the battery unit 1 can be made smaller.

[0022] [Strain gauge 100] Fig. 3 is a plan view illustrating the strain gauge according to the first embodiment. Fig. 4 is a cross-sectional view (part 1) illustrating the strain gauge according to the first embodiment, showing a cross section along line AA in Fig. 3.

[0023] 3 and 4, the strain gauge 100 has a substrate 110, a resistor 130, wiring 140, electrodes 150, and a cover layer 160. That is, the strain gauge 100 has the resistor 130 as a detection element. The cover layer 160 can be provided as necessary. For convenience, only the outer edge of the cover layer 160 is shown by a dashed line in FIG. 3 and FIG. 4. First, each part constituting the strain gauge 100 will be described in detail.

[0024] In addition, in FIG. 3 and FIG. 4, for convenience, in the strain gauge 100, the side of the substrate 110 on which the resistor 130 is provided is referred to as the "upper side", and the side on which the resistor 130 is not provided is referred to as the "lower side". In addition, the surface located on the upper side of each part is referred to as the "upper surface", and the surface located on the lower side of each part is referred to as the "lower surface". However, the strain gauge 100 can also be used upside down. In addition, the strain gauge 100 can also be arranged at any angle. In addition, the planar view refers to viewing the object in a normal direction from the upper side to the lower side with respect to the upper surface 110a of the substrate 110. In addition, the planar shape refers to the shape of the object when the object is viewed in the normal direction. The strain gauge 100 is attached to the outer peripheral surface of the battery cell so that the lower surface 110b of the substrate 110 faces the outer peripheral surface of the battery cell.

[0025] The substrate 110 is a member that serves as a base layer for forming the resistor 130 and the like. The substrate 110 is flexible. The thickness of the substrate 110 is not particularly limited and may be appropriately determined depending on the intended use of the strain gauge 100. For example, the thickness of the substrate 110 may be about 5 μm to 500 μm. From the viewpoint of the transferability of strain from the outer peripheral surface of the battery cell to the sensing part and the dimensional stability against environmental changes, the thickness of the substrate 110 is preferably within the range of 5 μm to 200 μm. From the viewpoint of insulation, the thickness of the substrate 110 is preferably 10 μm or more.

[0026] The substrate 110 is formed from an insulating resin film such as, for example, PI (polyimide) resin, epoxy resin, PEEK (polyether ether ketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, LCP (liquid crystal polymer) resin, polyolefin resin, etc. The film refers to a member having a thickness of about 500 μm or less and having flexibility.

[0027] When the base material 110 is formed from an insulating resin film, the insulating resin film may contain a filler, impurities, etc. For example, the base material 110 may be formed from an insulating resin film containing a filler such as silica or alumina.

[0028] Examples of materials other than resin for the base material 110 include crystalline materials such as SiO2, ZrO2 (including YSZ), Si, Si2N3, Al2O3 (including sapphire), ZnO, and perovskite ceramics (CaTiO3, BaTiO3). In addition to the above-mentioned crystalline materials, amorphous glass or the like may be used as the material for the base material 110. Metals such as aluminum, aluminum alloy (duralumin), and titanium may also be used as the material for the base material 110. When a metal base material 110 is used, an insulating film is provided so as to cover the upper surface 110a.

[0029] The resistor 130 is a thin film formed in a predetermined pattern on the upper side of the substrate 110. In the strain gauge 100, the resistor 130 is a sensing part that receives strain and generates a resistance change. The resistor 130 may be formed directly on the upper surface 110a of the substrate 110, or may be formed on the upper surface 110a of the substrate 110 via another layer. For convenience, the resistor 130 is shown in FIG. 3 as a dense matte pattern.

[0030] The resistor 130 has a structure in which multiple elongated parts are arranged at regular intervals with their longitudinal direction in the same direction (the direction of line AA in the example of FIG. 3), and the ends of adjacent elongated parts are alternately connected, folding back in a zigzag pattern as a whole. The longitudinal direction of the multiple elongated parts is the grid direction, and the direction perpendicular to the grid direction is the grid width direction (the direction perpendicular to line AA in the example of FIG. 3).

[0031] One end in the longitudinal direction of the two elongated portions located at the outermost sides in the grid width direction is bent in the grid width direction to form terminal ends 130e1 and 130e2 of the resistor 130 in the grid width direction. The terminal ends 130e1 and 130e2 of the resistor 130 in the grid width direction are electrically connected to the electrode 150 via the wiring 140. In other words, the wiring 140 electrically connects the terminal ends 130e1 and 130e2 of the resistor 130 in the grid width direction to the electrodes 150.

[0032] The resistor 130 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 130 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).

[0033] 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.

[0034] The thickness of the resistor 130 is not particularly limited and may be appropriately determined depending on the intended use of the strain gauge 100. For example, the thickness of the resistor 130 may be about 0.05 μm to 2 μm. In particular, when the thickness of the resistor 130 is 0.1 μm or more, the crystallinity of the crystals constituting the resistor 130 (for example, the crystallinity of α-Cr) is improved. Furthermore, when the thickness of the resistor 130 is 1 μm or less, (i) cracks in the film and (ii) warping of the film from the substrate 110 caused by the internal stress of the film constituting the resistor 130 are reduced.

[0035] Considering the need to prevent lateral sensitivity and to prevent disconnection, the width of resistor 130 is preferably 10 μm to 100 μm. More specifically, the width of resistor 130 is preferably 10 μm to 70 μm, and more preferably 10 μm to 50 μm.

[0036] For example, when the resistor 130 is a Cr mixed-phase film, the stability of the gauge characteristics can be improved by making α-Cr (alpha chromium) which is a stable crystal phase the main component. For example, when the resistor 130 is a Cr mixed-phase film, the resistor 130 can make α-Cr the main component, so that the gauge factor of the strain gauge 100 is 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 a component that occupies 50% by weight or more of the total material constituting the resistor. From the viewpoint of improving the gauge characteristics, the resistor 130 preferably contains 80% by weight or more of α-Cr. Furthermore, from the same viewpoint, the resistor 130 more preferably contains 90% by weight or more of α-Cr. Note that α-Cr is Cr with a bcc structure (body-centered cubic lattice structure).

[0037] In addition, when the resistor 130 is a Cr mixed-phase film, the Cr mixed-phase film preferably contains 20% by weight or less of CrN and Cr2N. By containing 20% ​​by weight or less of CrN and Cr2N in the Cr mixed-phase film, a decrease in the gauge factor of the strain gauge 100 can be suppressed.

[0038] In addition, the ratio of CrN and Cr2N in the Cr mixed phase film is preferably such that the ratio of Cr2N is 80% by weight or more and less than 90% by weight with respect to the total weight of CrN and Cr2N. More specifically, the ratio is more preferably such that the ratio of Cr2N is 90% by weight or more and less than 95% by weight with respect to the total weight of CrN and Cr2N. Cr2N has semiconductor properties. Therefore, by setting the ratio of Cr2N to 90% by weight or more and less than 95% by weight, the decrease in TCR (negative TCR) becomes more significant. Furthermore, by setting the ratio of Cr2N to 90% by weight or more and less than 95% by weight, the resistor 130 is less likely to become ceramic, and the resistor 130 is less likely to be brittle fractured.

[0039] On the other hand, CrN has the advantage of being chemically stable. By including more CrN in the Cr mixed-phase film, the possibility of unstable N being generated can be reduced, resulting in a stable strain gauge. Here, "unstable N" refers to trace amounts of N2 or atomic N that may be present in the Cr mixed-phase film. This unstable N may escape to the outside of the film depending on the external environment (e.g., high-temperature environment). When unstable N escapes to the outside of the film, the film stress of the Cr mixed-phase film may change.

[0040] In the strain gauge 100, when a Cr mixed-phase film is used as the material of the resistor 130, it is possible to realize high sensitivity and miniaturization. For example, while the output of a conventional strain gauge was about 0.04 mV / 2 V, when a Cr mixed-phase film is used as the material of the resistor 130, an output of 0.3 mV / 2 V or more can be obtained. In addition, while the size (gauge length x gauge width) of a conventional strain gauge was about 3 mm x 3 mm, when a Cr mixed-phase film is used as the material of the resistor 130, the size (gauge length x gauge width) can be miniaturized to about 0.3 mm x 0.3 mm.

[0041] The wiring 140 is provided on the substrate 110. The wiring 140 is electrically connected to the resistor 130 and the electrode 150. The wiring 140 is not limited to being linear, and may be in any pattern. The wiring 140 may have any width and any length. For convenience, the wiring 140 is shown in FIG. 3 as having a matte pattern with a lower density than the resistor 130.

[0042] The electrode 150 is provided on the substrate 110. The electrode 150 is electrically connected to the resistor 130 via the wiring 140. The electrode 150 is formed in a substantially rectangular shape wider than the wiring 140 in a plan view. The electrodes 150 are a pair of electrodes for outputting a change in the resistance value of the resistor 130 caused by distortion to the outside. A metal layer having low resistance such as copper or a metal layer having good solderability such as gold may be laminated on the upper surface of the electrode 150. Although the resistor 130, the wiring 140, and the electrode 150 are denoted by different reference numerals for convenience, they can be integrally formed from the same material in the same process. In FIG. 3, the electrode 150 is shown with a matte pattern having the same density as the wiring 140 for convenience.

[0043] The cover layer 160 (protective layer) is provided on the upper surface 110a of the base material 110 as necessary so as to cover the resistor 130 and the wiring 140 and expose the electrodes 150. Examples of materials for the cover layer 160 include insulating resins such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, and composite resins (e.g., silicone resin, polyolefin resin). The cover layer 160 may contain a filler or a pigment. The thickness of the cover layer 160 is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness of the cover layer 160 can be about 2 μm to 30 μm. By providing the cover layer 160, it is possible to suppress mechanical damage and the like from occurring in the resistor 130. In addition, by providing the cover layer 160, it is possible to protect the resistor 130 from moisture and the like.

[0044] [Manufacturing method of strain gauge 100] In the strain gauge 100 according to this embodiment, a resistor 130, wiring 140, electrodes 150, and a cover layer 160 are formed on a substrate 110. Note that another layer (such as a functional layer described below) may be formed between the substrate 110 and the layers of these members.

[0045] A method for manufacturing the strain gauge 100 will be described below. To manufacture the strain gauge 100, first, a base material 110 is prepared, and a metal layer (for convenience, referred to as metal layer A) is formed on an upper surface 110a of the base material 110. The metal layer A is a layer that is finally patterned to become the resistor 130, the wiring 140, and the electrodes 150. Therefore, the material and thickness of the metal layer A are the same as the material and thickness of the resistor 130, the wiring 140, and the electrodes 150 described above.

[0046] The metal layer A can be formed by, for example, magnetron sputtering using a target made of a raw material capable of forming the metal layer A. Instead of magnetron sputtering, the metal layer A may be formed by reactive sputtering, vapor deposition, arc ion plating, pulsed laser deposition, or the like. After the metal layer A is formed on the upper surface 110a of the base material 110, the metal layer A is patterned by a well-known photolithography method into a planar shape similar to that of the resistor 130, the wiring 140, and the electrode 150 in FIG. 3.

[0047] Alternatively, a base layer may be formed on the upper surface 110a of the base material 110, and then the metal layer A may be formed. For example, a functional layer of a predetermined thickness may be vacuum-formed by conventional sputtering on the upper surface 110a of the base material 110. By providing a base layer in this manner, the gauge characteristics of the strain gauge 100 can be stabilized.

[0048] 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, metal layer A (resistor 130). The functional layer preferably further has a function of preventing oxidation of metal layer A due to oxygen or moisture contained in base material 110, and / or a function of improving adhesion between base material 110 and metal layer A. The functional layer may further have other functions.

[0049] The insulating resin film constituting the base material 110 may contain oxygen or moisture, and Cr may form a self-oxidized film. Therefore, particularly when the metal layer A contains Cr, it is preferable to form a functional layer having a function of preventing the oxidation of the metal layer A.

[0050] In this way, by providing a functional layer below the metal layer A, it is possible to promote crystal growth of the metal layer A, and to fabricate a metal layer A consisting of a stable crystal phase. As a result, the stability of the gauge characteristics of the strain gauge 100 is improved. In addition, the material constituting the functional layer diffuses into the metal layer A, thereby improving the gauge characteristics of the strain gauge 100.

[0051] Examples of materials for the functional layer include one or more metals selected from the group consisting of 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), 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.

[0052] 5 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. FIG 5 shows the cross-sectional shape of the strain gauge 100 when a functional layer 120 is provided as an underlayer for the resistor 130, the wiring 140, and the electrodes 150.

[0053] The planar shape of the functional layer 120 may be patterned to be substantially the same as the planar shapes of the resistor 130, the wiring 140, and the electrode 150, for example. However, the planar shapes of the functional layer 120, the resistor 130, the wiring 140, and the electrode 150 may not be substantially the same. For example, when the functional layer 120 is formed from an insulating material, the functional layer 120 may be patterned to be different from the planar shapes of the resistor 130, the wiring 140, and the electrode 150. In this case, the functional layer 120 may be formed in a solid shape in the region where the resistor 130, the wiring 140, and the electrode 150 are formed, for example. Alternatively, the functional layer 120 may be formed in a solid shape on the entire upper surface of the substrate 110.

[0054] After forming the resistor 130, the wiring 140, and the electrodes 150, a cover layer 160 is formed on the upper surface 110a of the base material 110 as necessary. The cover layer 160 covers the resistor 130 and the wiring 140, but the electrodes 150 may be exposed from the cover layer 160. For example, the cover layer 160 can be formed by laminating a semi-cured thermosetting insulating resin film on the upper surface 110a of the base material 110 so as to cover the resistor 130 and the wiring 140 and expose the electrodes 150, and then heating and curing the insulating resin film. Through the above steps, the strain gauge 100 is completed.

[0055] Modification of the First Embodiment In the modified example of the first embodiment, examples of battery units in which the method of attaching the strain gauges and the shape of the battery cells are different are shown. Note that in the modified example of the first embodiment, the description of the same components as those in the embodiment already described may be omitted.

[0056] FIG. 6 is a diagram illustrating a battery unit according to Modification 1 of the first embodiment, and is a diagram showing the battery unit 1A as viewed in the same direction as the arrow S in FIG.

[0057] As shown in FIG. 6, the battery unit 1A differs from the battery unit 1 in that the strain gauges 100 of the battery cells 10 and 20 are attached to the same side (the lower side in FIG. 6).

[0058] In this manner, the strain gauges 100 of the battery cells 10 and 20 may be attached on opposite sides as shown in Fig. 2, or on the same side as shown in Fig. 6. Also, when there are three or more battery cells, the strain gauges 100 may be attached on opposite sides or on the same side.

[0059] The position of the electrodes 150 can be changed arbitrarily in the strain gauge 100. For example, if a pair of electrodes 150 are arranged to face each other across the resistor 130 at the center in the grid width direction, a strain gauge of the same specifications can be used whether they are attached to opposite sides as shown in Fig. 2 or to the same side as shown in Fig. 6.

[0060] FIG. 7 is a diagram illustrating a battery unit according to Modification 2 of the first embodiment, and is a diagram showing the battery unit 1B as viewed in the same direction as the arrow S in FIG.

[0061] 7, the battery unit 1B differs from the battery unit 1 in that the battery cells 10 and 20 are substantially rectangular prism-shaped. In this manner, the shape of the battery cells is not limited to a cylindrical shape, and may be a rectangular prism. Alternatively, the shape of the battery cells may be another polygonal prism, such as a triangular prism.

[0062] Of course, no matter what polygonal column shape the battery cell is, each strain gauge 100 may be attached on the opposite side as shown in Fig. 2, or on the same side as shown in Fig. 6. Also, when there are three or more battery cells, each strain gauge 100 may be attached on the opposite side or on the same side.

[0063] Second Embodiment In the second embodiment, an example of a battery unit having a plurality of battery groups will be described. Note that in the second embodiment, the description of the same components as those in the embodiments already described may be omitted.

[0064] FIG. 8 is a schematic diagram illustrating a battery unit according to the second embodiment.

[0065] As shown in Fig. 8, the battery unit 2 has battery groups 201 and 202. The configuration of each of the battery groups 201 and 202 is similar to that of the battery unit 1 according to the first embodiment. In the example of Fig. 8, in each of the battery groups 201 and 202, the battery cell 10 and the battery cell 20 are connected in parallel, but they may be connected directly. In addition, when each of the battery groups 201 and 202 has more battery cells, for example, a configuration in which a group of multiple battery cells connected in parallel is connected in series may be used.

[0066] The battery group 201 and the battery group 202 are connected in parallel via wiring 203 and 204. Terminals are indicated by 205 and 206. One of the terminals 205 and 206 is a positive terminal, and the other is a negative terminal.

[0067] In the battery unit 2, similarly to the battery unit 1, one electrodes 150 of the strain gauges 100 attached to adjacent battery cells are directly joined to each other via a conductive joint 200. Therefore, similarly to the battery unit 1, the battery unit 2 can be made compact.

[0068] <Modification of the second embodiment> In the modified example of the second embodiment, an example of a battery unit having a mechanism for cutting off a circuit in the event of an abnormality is shown. Note that in the modified example of the second embodiment, the description of the same components as those in the embodiment already described may be omitted.

[0069] 9 is a schematic diagram illustrating a battery unit according to Modification 1 of the second embodiment. As shown in FIG. 9, the battery unit 2A has an abnormality determination unit 300, a circuit breaker unit 401, and a circuit breaker unit 402 in addition to the configuration of the battery unit 2.

[0070] In the battery unit 2A, the outputs of the two strain gauges 100 connected in series in the battery group 201 are input to the abnormality determination section 300. Similarly, the outputs of the two strain gauges 100 connected in series in the battery group 202 are input to the abnormality determination section 300.

[0071] A circuit breaker unit 401 is inserted in the wiring 203 between the terminal 205 and the battery group 201. Also, a circuit breaker unit 402 is inserted in the wiring 203 between the terminal 205 and the battery group 202. The circuit breakers 401 and 402 are normally in a conductive state, and can be switched to a cut-off state by an external control signal. The circuit breakers 401 and 402 are, for example, switches that can be controlled from the outside. Specifically, for example, a mechanical switch such as a relay, or an electronic switch equipped with a transistor or the like can be mentioned.

[0072] The abnormality determination unit 300 can determine an abnormality in each battery group based on the output of the strain gauge 100 connected in series to each battery group. Specifically, the abnormality determination unit 300 can determine whether or not the battery cells of the battery groups 201 and 202 have expanded or contracted by monitoring the resistance value of the strain gauge 100 of each of the battery groups 201 and 202.

[0073] For example, when the degree of expansion or contraction exceeds a predetermined threshold, the abnormality determination unit 300 can determine that an abnormality has occurred in the battery group 201 and / or 202. Furthermore, the abnormality determination unit 300 can output a control signal for breaking the circuit to a circuit breaker unit inserted between the battery group determined to have an abnormality and the terminal 205. Then, the circuit breaker unit can break the circuit of the battery group determined to have an abnormality based on the control signal that is the determination result of the abnormality determination unit 300.

[0074] For example, when the abnormality determination unit 300 determines that an abnormality has occurred in the battery group 202, it outputs a control signal for breaking the circuit to the circuit breaker unit 402 inserted in the wiring 203 between the battery group 202 and the terminal 205. Based on this control signal, the circuit breaker unit 402 breaks the battery group 202 determined to be abnormal.

[0075] Even if battery group 202 is cut off, because battery group 201 is connected between terminals 205 and 206, a normal voltage output is obtained from terminals 205 and 206, and battery unit 2A can continue to operate normally. That is, battery unit 2A ensures safety by cutting off the abnormal battery group, and can continue to operate as a battery by keeping the normal battery group alive.

[0076] Fig. 10 is a diagram illustrating an example of the abnormality determination unit. As shown in Fig. 10, the abnormality determination unit 300 can include, for example, an analog front-end unit 310 and a control unit 320. The output of each strain gauge 100 of the battery groups 201 and 202 is connected to the analog front-end unit 310.

[0077] The analog front-end unit 310 includes, for example, a bridge circuit, an amplifier circuit, an A / D conversion circuit (analog / digital conversion circuit), and generates a strain waveform based on the output of the strain gauge. The analog front-end unit 310 may include a temperature compensation circuit. The analog front-end unit 310 may be implemented as an IC or may be configured with individual components.

[0078] The analog front-end section 310 has two bridge circuits, one connecting the outputs of the strain gauges 100 in the battery group 201 and the other connecting the outputs of the strain gauges 100 in the battery group 202, but amplifiers etc. may be provided separately or may be common to both.

[0079] In the analog front-end unit 310, a strain waveform corresponding to the output of each of the strain gauges 100 of the battery groups 201 and 202 is output from the bridge circuit, amplified by the amplifier circuit, converted into a digital signal by the A / D conversion circuit, and output to the control unit 320. If the analog front-end unit 310 includes a temperature compensation circuit, a temperature compensated digital signal is sent to the control unit 320.

[0080] The control unit 320 performs arithmetic processing on the digitized distortion waveform sent from the analog front-end unit 310 to monitor the expansion and contraction of the battery cells. The arithmetic processing includes, for example, comparing the distortion waveform with a predetermined threshold value. Based on the result of the arithmetic processing, the control unit 320 can output a control signal for interrupting the circuit to a circuit interrupter inserted in the wiring 203 between the battery group and the terminal 205.

[0081] Fig. 11 is an example of a hardware block diagram of the control unit. As shown in Fig. 11, the control unit 320 has, as main components, a CPU (Central Processing Unit) 321, a ROM (Read Only Memory) 322, a RAM (Random Access Memory) 323, an I / F (Interface) 324, and a bus line 325. The CPU 321, the ROM 322, the RAM 323, and the I / F 324 are connected to each other via the bus line 325. The control unit 320 may have other hardware blocks as necessary.

[0082] The CPU 321 controls each function of the control unit 320. The ROM 322, which is a storage means, stores various information and programs executed by the CPU 321 to control each function of the control unit 320. The RAM 323, which is a storage means, is used as a work area or the like for the CPU 321. The RAM 323 can also temporarily store predetermined information. The I / F 324 is an interface for connecting to other devices and the like, and is connected to, for example, the analog front-end unit 310, an external network, and the like.

[0083] The control unit 320 may be a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, or an ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), SOC (System On a Chip), or GPU (Graphics Processing Unit) designed to execute a predetermined function. The control unit 320 may also be a circuit module, etc.

[0084] In this way, by providing the abnormality determination unit 300 and the circuit breaker units 401 and 402 in the battery unit 2A, the degree of expansion or contraction of each battery cell of the battery groups 201 and 202 can be detected as a change in the resistance value of the resistor of the strain gauge 100. Then, in the event of an abnormality, the battery groups 201 and / or 202 are cut off by the circuit breaker units 401 and / or 402 based on the control of the abnormality determination unit 300, thereby preventing damage to the battery cells and improving the safety of the battery unit 2A.

[0085] In particular, when resistor 130 is formed from a Cr mixed phase film, the sensitivity of the resistance value to the expansion and contraction of the battery cell is significantly improved compared to when resistor 130 is formed from Cu-Ni or Ni-Cr. When resistor 130 is formed from a Cr mixed phase film, the sensitivity of the resistance value to the expansion and contraction of the battery cell is approximately 5 to 10 times higher compared to when resistor 130 is formed from Cu-Ni or Ni-Cr. Therefore, by forming resistor 130 from a Cr mixed phase film, it becomes possible to accurately detect the expansion and contraction of the battery cell.

[0086] In each embodiment, a label-integrated strain gauge may be used. Fig. 12 is a plan view illustrating a label-integrated strain gauge. As shown in Fig. 12, the strain gauge 100A has a label 500. The label 500 is provided on the top layer of the strain gauge 100A. The label 500 can be provided on the top layer of the strain gauge 100A by, for example, a printing method.

[0087] Here, the top layer refers to a position that is visible even after the strain gauge 100A is attached to an object. The top layer is, for example, the top surface of the cover layer 160. If the strain gauge 100A does not have the cover layer 160, the label 500 may be provided in a region of the top surface 110a of the base material 110 where the resistor 130 is formed or a region where the resistor 130 is not formed. In this case, the region of the top surface 110a of the base material 110 where the resistor 130 is formed or a region where the resistor 130 is not formed becomes the top layer.

[0088] For example, information about the battery cell is displayed on the label 500. Information about the strain gauge 100A may be displayed on the label 500 together with the information about the battery cell. The content displayed on the label 500 (the "ABCDE" portion in FIG. 12) is, for example, a logo mark, product information, product number, character string, numeric string, one-dimensional code, two-dimensional code, etc. These may be displayed alone or in a mixture of two or more.

[0089] If information is displayed on the battery cell itself, the information may be hidden by attaching the strain gauge 100A. By providing the label 500 having information about the battery cell to the strain gauge 100A in advance, the strain gauge 100A can be attached to the battery cell without worrying about the information displayed on the battery cell being hidden.

[0090] Moreover, by providing label 500 on strain gauge 100A in advance, it is possible to omit the step of printing label 500 on strain gauge 100A after attaching strain gauge 100A to a battery cell. Also, providing label 500 on strain gauge 100A can contribute to space saving.

[0091] Furthermore, when information about the strain gauge 100A is displayed on the label 500 together with information about the battery cell, there is no need to provide a separate label displaying information about the strain gauge 100A, which leads to a reduction in labor hours.

[0092] Furthermore, by providing label 500 to strain gauge 100A, label 500 also functions as a protective member, making it possible to reduce the effects of disturbances applied to the battery cell and strain gauge.

[0093] Third embodiment In the above-described embodiments and the modified examples thereof, examples have been described in which the detection unit according to the present disclosure is a strain gauge using a resistor. That is, in the above-described embodiments, 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 strain body (or a structure equivalent to a strain body such as a battery cell 10) by a detection element included in the strain gauge.

[0094] Specifically, the detection unit according to the present disclosure may be a strain gauge including a detection element utilizing 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 following, in the third embodiment, a strain gauge including a detection element utilizing the Villari phenomenon will be described. In the fourth embodiment, a strain gauge including a detection element having a magnetic tunnel junction structure will be described.

[0095] In each embodiment of this specification, components having similar functions are given similar names and numbers, and descriptions will not be repeated. In addition, the directions of the x-axis, y-axis, and z-axis are the same in each drawing (drawings from FIG. 13 onward) relating to each embodiment below. In addition, 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.

[0096] FIG. 13 is a diagram showing an example of a detection element 600 included in a strain gauge according to the third embodiment. FIG. 13(a) is a plan view of the detection element 600 when viewed from the positive to negative direction of the z axis (i.e., from the top to the bottom). Meanwhile, FIG. 13(b) shows a cross-sectional view of the detection element 600 shown in FIG. 13(a) along line α-α'. Note that, in FIG. 13(a) and (b), wiring extending from the detection element 600 is not shown. However, the detection element 600 may be connected to wiring connecting a drive coil 620 and a power source, which will be described later, and wiring for transmitting a current detected by a sensing coil 680.

[0097] As shown in FIG. 13(a), the detection element 600 includes a driving coil 620, a sensing coil 680, and a base layer 610. The base layer 610 is a layer that serves as a core material for the driving coil 620 and the sensing coil 680. The sensing coil 680 is a coil for detecting the intensity of magnetization of the base layer 610 (more precisely, a base metal 670 described later). The driving coil 620 is a coil for generating a magnetic field. The detection element 600 has a double structure in which the sensing coil 680 is wound on the inside and the driving coil 620 is wound on the outside, with the base layer 610 as the core material. The materials for the driving coil 620 and the sensing coil 680 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 620 and the sensing coil 680 may be appropriately designed according to the strain detection sensitivity required for the detection element 600.

[0098] As will be described in detail later, when stress is applied to the base layer 610, the strength of magnetization of a base metal 670 (described later) included in the base layer 610 changes. The detection element 600 can determine the strength of the stress applied to the base layer 610 (i.e., the degree of strain) by detecting this change in the strength of magnetization with the sensing coil 680.

[0099] The configuration of the detection element 600 will be further described with reference to the cross-sectional view of (b) of Fig. 13. In Fig. 13(b), the driving coil 620, the sensing coil 680, and the three insulating layers 640, 650, and 660 are each formed to surround the base metal 670, which is the core material. That is, the layers with the same component number in (b) of Fig. 13 are connected to surround the base metal 670.

[0100] The base metal 670 is a member that serves as a core material for various coils and insulating layers. The base metal 670 may be, for example, a substantially flat metal plate. The base metal 670 is covered so as to be surrounded by an insulating layer 660. The base metal 670 is preferably made of a soft magnetic material such as an Fe-Si-Al alloy such as sendust, and an Ni-Fe alloy such as permalloy. The aforementioned base layer 610 is made of the base metal 670 and the insulating layer 660, as shown in FIG. 13(b).

[0101] An insulating layer 650 is formed on the outside of the insulating layer 660 so as to surround the insulating layer 660. An insulating layer 640 is further formed on the outside of the insulating layer 650. The insulating layer 650 is a layer including the sensing coil 680, and is a layer in which the gaps in the sensing coil 680 are filled with an insulating material. The insulating layer 640 is a layer including the driving coil 620, and is a layer in which the gaps in the driving coil 620 are filled with an insulating material. The insulating layers 640, 650, and 660 are desirably made of a dry film that does not affect the magnetic field or a resist cured material such as photosensitive polyimide.

[0102] One surface of the detection element 600 may be attached to the substrate 110 as shown in FIG. 13(b). The substrate 110 is a member for fixing the detection element 600. For example, the substrate 110 may be a flexible substrate made of a plastic film or the like. The detection element 600 is attached to the battery cell 10 or the like via the substrate 110. The detection element 600 may be a flat or thin-film detection element as a whole. When the detection element 600 is flat or thin-film, the detection element 600 can be attached to the substrate 110 more easily. In addition, the substrate 110 is not an essential component of the detection element 600. For example, the detection element 600 may be used by directly attaching the lower surface of the detection element 600 to the battery cell 10 or the like without providing the substrate 110 to the detection element 600.

[0103] In the battery cell 10 according to the present embodiment, the portion to which the detection element 600 is attached is preferably made of a non-magnetic material. In the battery cell 10 according to the present embodiment, the portion to which the detection element 600 is attached is preferably made of aluminum, for example.

[0104] Next, the principle of detecting strain using the detection element 600 will be outlined. The detection element 600 includes a base metal 670, which is a magnetic material. When an alternating current is supplied from a power source to the drive coil 620, the drive coil 620 generates an alternating magnetic field around it. This generates a magnetic field, and the base metal 670 is magnetized. If the battery cell 10 or the like is deformed in this state, strain occurs. The strain is transmitted through the substrate 110, and stress is applied to the base metal 670. Note that when the detection element 600 is attached to the battery cell 10 or the like without the substrate 110, stress is transmitted directly from the battery cell 10 or the like to the base metal 670 (and the insulating layers 640 to 660 covering it).

[0105] When stress is applied to the base metal 670, the magnetic permeability of the base metal 670 changes according to the stress. Therefore, the strength of magnetization (degree of magnetization) of the base metal 670 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 600, an AC voltage corresponding to the strength of magnetization of the base metal 670 is induced in the sensing coil 680, which is a pickup coil. Therefore, based on the principle of the Villari phenomenon, the stress applied to the base metal 670 can be calculated from the value of this AC voltage. Then, the degree of strain of the battery cell 10, etc. can be specified from the calculated stress. Note that when the detection element 600 has the shape shown in (a) and (b) of FIG. 13, the grid direction of the detection element 600 is equal to the α-α' direction in (a) of FIG. 13. Based on the principle described above, the detection element 600 can detect strain of the battery cell 10, etc. That is, the sensing element 600 functions as a sensing element of a strain gauge.

[0106] It is desirable that the driving coil 620 is wound as uniformly as possible around the outside of the sensing coil 680 and over the entire area in which the sensing coil 680 exists. This allows an alternating magnetic field to be applied more uniformly to the entire area of ​​the base metal 670 in which the sensing coil 680 exists. This allows the change in the strength of magnetization of the base metal 670 due to the Villari phenomenon to be detected more precisely. This improves the performance of the detection element 600.

[0107] Furthermore, the insulating layer 660 may be formed on only a part of the base metal 670 rather than on the entirety of the base metal 670. For example, the region of the base metal 670 around which the sensing coil 680 and the driving coil 620 are wound may be covered with the insulating layer 660, the insulating layer 660 may be covered with the insulating layer 650 including the sensing coil 680, and the insulating layer 650 may be covered with the insulating layer 640 including the driving coil 620.

[0108] In addition, when the base metal 670 is substantially plate-shaped, the insulating layer 660 may be formed to surround only the base metal 670 in the winding direction of the coil. That is, in (b) of FIG. 13, both ends of the base metal 670 in the x direction do not need to be covered with the insulating layer 660.

[0109] In the battery unit according to this embodiment, when the battery cell 10 or the like is deformed (i.e., strain occurs in the strain body), the substrate 110 of the strain gauge (or the detection element 600 itself) is strained. The detection element 600 can detect the magnetic change caused by this strain based on the principle of the Villari phenomenon described above.

[0110] The strain gauge including the detection element 600 according to this embodiment can be arranged in the battery cell 10 or the like in any arrangement pattern shown in the first embodiment and the modified example of the first embodiment. That is, the detection element 600 according to this embodiment can be used to detect strain in the battery cell 10 or the like in the same manner as when an electrical resistance type strain gauge is used. Therefore, the strain gauge according to this embodiment has the same effects as the strain gauge 100 according to the first embodiment and the modified example of the first embodiment.

[0111] Fourth embodiment FIG. 14 is a diagram showing a detection element 700, which is an example of a detection element included in the strain gauge according to the fourth embodiment. FIG. 15 is a diagram showing a detection element 800, which is another example of the detection element according to the fourth embodiment. FIG. 16 is a diagram showing a detection element 900, which is yet another example of the detection element according to the fourth embodiment. (a) of FIG. 14 to 16 is a perspective view of the detection elements 700, 800, and 900, respectively. (b) of FIG. 14 to 16 is a plan view of the detection elements 700, 800, and 900, respectively, when viewed from the positive direction to the negative direction of the z axis. (c) of FIG. 14 to 16 is a cross-sectional view of the detection elements 700, 800, and 900 on a surface parallel to the zx plane. Note that wiring extending from the detection elements is not shown in any of FIG. 14 to 16. However, these detection elements 700, 800, and 900 may be connected to a wiring that connects an upstream electrode 710 to a power source, and a wiring that connects a downstream electrode 720 to a power source, which will be described later.

[0112] As shown in (a) of Figures 14 to 16, the detection elements 700, 800, and 900 include an upstream electrode 710, a downstream electrode 720, a magnetic film 730, and an insulating film 740. The insulating film 740 is sandwiched between the magnetic films 730 as shown in the figures. A magnetic tunnel junction is formed by the magnetic film 730 and the insulating film 740. In other words, the detection elements 700, 800, and 900 have a structure in which electrodes are connected to a magnetic tunnel junction structure.

[0113] The lower surfaces of the detection elements 700, 800, and 900 may be attached to a substrate similar to the substrate 110 according to the first embodiment. The detection element 700 may be attached to the battery cell 10 or the like via the substrate. The detection elements 700, 800, and 900 may be flat-plate or thin-film detection elements as a whole. When the detection elements 700, 800, and 900 are flat-plate or thin-film, the detection elements 700, 800, and 900 can be more easily attached to the substrate or the battery cell 10 or the like. For example, the lower surfaces of the detection elements 700, 800, and 900 may be directly attached to the battery cell 10 or the like for use.

[0114] The magnetic film 730 is a magnetic nano-thin film. The insulating film 740 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 730 and the insulating film 740 are not particularly limited. For example, the magnetic film 730 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 740 can be made of silicon oxide, silicon nitride, aluminum oxide, magnesium oxide, or the like.

[0115] The upstream electrode 710 and the downstream electrode 720 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 710 to the downstream electrode 720. For example, in the case of FIG. 14(c), when a voltage is applied between the upstream electrode 710 and the downstream electrode 720, electrons flow from the upper magnetic film 730 (the positive z-axis side) to the lower magnetic film 730 (the negative z-axis side) over the insulating film 740. This is a phenomenon called the "tunnel effect", and the electrical resistance when electrons pass through the insulating film 740 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.

[0116] Incidentally, when a strain is applied to the detection element 700 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 730 are shifted. When the magnetization directions of the upper and lower magnetic films 730 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 700 having the above-mentioned configuration, the current flowing between the electrodes becomes smaller according to the magnitude of the strain of the detection element 700 (more precisely, the magnetic tunnel junction part). That is, as the strain increases, the electric resistance increases. In this way, the detection element 700 can detect the strain based on the current value relative to the applied voltage. Therefore, by attaching the detection element 700 to the battery cell 10 or the like, the strain applied to the battery cell 10 or the like can be measured.

[0117] The detection element having the magnetic tunnel junction structure is not limited to the example shown in FIG. 14. For example, detection elements 800 and 900 shown in FIG. 15 and FIG. 16 can be adopted. The detection element 800 shown in FIG. 15 and the detection element 900 shown in FIG. 16 are both configured with an upstream electrode 710, a downstream electrode 720, a magnetic film 730, and an insulating film 740, and the principle of detecting strain by these configurations is the same as that of the detection element 700. The basic operation of the detection elements 800 and 900 is also the same as that of the detection element 700. The grid directions of the detection elements 700, 800, and 900 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 800 shown in FIG. 15 has a structure in which the upper magnetic film 730 and the lower magnetic film 730 are partially connected. That is, a magnetic tunnel junction structure is formed only in a partial region of the magnetic film 730, and a tunnel magnetoresistance effect occurs in this structure. Meanwhile, a detection element 900 shown in Fig. 16 is attached to a base material 110 via a substrate 910. 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 stress to be detected, and the like, as long as it does not exceed the above-mentioned principle.

[0118] In the battery cell 10 according to the present embodiment, the portion to which the detection element 700, 800, or 900 is attached is preferably made of a non-magnetic material. In the battery cell 10 according to the present embodiment, the portion to which the detection element 700, 800, or 900 is attached is preferably made of aluminum, for example. The detection elements 700, 800, and 900 may have a substantially flat plate shape such as a film type as an entire element. This allows the detection element 700 to be easily attached to the battery cell 10, etc. The detection elements 700, 800, and 900 may have a structure for applying a weak magnetic field to the structural part of the magnetic tunnel junction, such as a 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.

[0119] In addition, the "upstream electrode" and the "downstream electrode" in the detection elements 700, 800, and 900 are names for convenience, and the direction of current flow may be reversed. That is, the detection elements 700, 800, and 900 shown in Figs. 14 to 16 may be designed so that the current flows from the downstream electrode 720 to the upstream electrode 710.

[0120] In the battery unit according to this embodiment, when the battery cell 10 or the like is deformed (i.e., strain occurs in the strain body), the substrate of the strain gauge (or the detection element 700, 800, or 900 itself) is strained. The detection element 700, 800, or 900 can detect the magnetic change caused by this strain based on the principle of the tunnel magnetoresistance effect described above.

[0121] The strain gauge including the detection elements 700, 800, and 900 according to this embodiment can be arranged in the battery cell 10 or the like in any arrangement position shown in the first embodiment and the modified example of the first embodiment. That is, the detection elements 700, 800, and 900 according to this embodiment can be used to detect strain in the battery cell 10 or the like in the same manner as when an electrical resistance type strain gauge is used. Therefore, the strain gauge according to this embodiment has the same effect as the strain gauge 100 according to the first embodiment and the modified example of the first embodiment.

[0122] Fifth 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.

[0123] (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.

[0124] It is known that when stress is applied to a semiconductor, strain is generated in the crystal lattice of the semiconductor, causing changes in the number and mobility of carriers in the semiconductor, resulting in a change in electrical resistance. A semiconductor-type strain gauge can be directly attached to a battery cell 10 or the like for use, similar to an electrical resistance-type metal strain gauge. In this case, when the battery cell 10 or the like expands or contracts, the strain electrical resistance of the attached semiconductor (more specifically, the crystal lattice of the semiconductor) changes. Therefore, the amount of strain in the battery cell 10 or the like can be identified by measuring the electrical resistance.

[0125] 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 battery cell 10, etc.) can be identified by measuring the electrical resistance.

[0126] (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).

[0127] 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.

[0128] (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.

[0129] By attaching an optical fiber having such characteristics to the battery cell 10 or the like 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 battery cell 10 or the like) can be identified. Note that the optical fiber type strain gauge may be a strain gauge that identifies the amount of strain in the optical fiber from a change in the frequency of the Brillouin scattered light generated in the optical fiber.

[0130] (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.

[0131] (Vibration pressure sensor) The 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. The vibration pressure sensor can be directly attached to a battery cell 10 or the like for use, similar to an electrical resistance type metal strain gauge. For example, the 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.

[0132] In either case, when the battery cell 10 or the like is distorted, the pressure is directly or indirectly transmitted to the vibrator, and an axial force is generated in the vibrator. The natural frequency of the vibrator changes according to the axial force. Therefore, by measuring the natural frequency of the vibrator, the magnitude of the pressure on the battery cell 10 or the like can be determined.

[0133] (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.

[0134] A piezoelectric pressure sensor can measure the electromotive force of a piezoelectric element to determine the force applied to the piezoelectric element (i.e., the amount of strain of the piezoelectric element). Therefore, by attaching a piezoelectric pressure sensor to a battery cell 10 or the like, the amount of strain of the battery cell 10 or the like can be determined.

[0135] As described above, the same effects as those of the strain gauge 100 according to the first embodiment and the modified example of the first embodiment can be obtained even when a semiconductor strain gauge, a capacitance pressure sensor, an optical fiber strain gauge, a mechanical pressure sensor, a vibration pressure sensor, and a piezoelectric pressure sensor are used.

[0136] 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]

[0137] 1, 1A, 1B, 2, 2A battery unit, 10, 20 battery cell, 10a, 10b, 20a, 20b end surface, 10c, 20c outer surface, 100, 100A strain gauge, 110 substrate, 110a upper surface, 120 functional layer, 130 resistor, 130e1, 130e2 termination, 140 wiring, 150 electrode, 160 cover layer, 200 joint, 201, 202 battery group, 203, 204 wiring, 205, 206 terminal, 300 abnormality determination unit, 310 analog front end unit, 320 control unit, 321 CPU, 322 ROM, 323 RAM, 324 I / F, 325 bus line, 401, 402 circuit breaker unit, 500 Label, 600, 700, 800, 900, sensing element, 610, base layer, 620, driving coil, 640, 650, 660, insulating layer, 670, base metal, 680, sensing coil, 710, upstream electrode, 720, downstream electrode, 730, magnetic film, 740, insulating film, 910, substrate

Claims

1. Multiple battery cells, Each of the aforementioned battery cells has a strain gauge attached to its outer surface, Each of the aforementioned strain gauges comprises a pair of electrodes electrically connected to a sensing element, A battery unit in which one electrode of each strain gauge attached to adjacent battery cells is joined to the other via a conductive joint, and all of the strain gauges are connected in series.

2. The battery unit according to claim 1, wherein the joint directly joins the opposing surfaces of the electrodes of the strain gauges attached to adjacent battery cells.

3. It has multiple battery groups, Each of the aforementioned battery groups is, Multiple battery cells, The device comprises the strain gauge attached to the outer surface of each of the aforementioned battery cells, The battery unit according to claim 1, wherein in each of the battery groups, one electrode of the strain gauge attached to an adjacent battery cell is joined to the other via the conductive joint, and all of the strain gauges are connected in series.

4. The battery unit according to claim 3, wherein each of the aforementioned battery groups is connected in parallel.

5. It further includes an abnormality detection unit and a circuit interruption unit, The abnormality determination unit determines whether each of the battery groups is abnormal based on the output of the strain gauges connected in series to each of the battery groups. The battery unit according to claim 3 or 4, wherein the circuit interruption unit interrupts the battery group that has been determined to be abnormal based on the determination result of the abnormality determination unit.

6. The battery unit according to any one of claims 1 to 4, wherein each of the strain gauges has a label on the uppermost layer.

7. The battery unit according to claim 6, wherein the label displays information relating to the battery cell.

8. The battery unit according to claim 7, wherein the label displays information regarding the strain gauge.

9. Multiple battery cells, Each of the aforementioned battery cells has a detection unit attached to its outer peripheral surface, Each of the aforementioned detection units is equipped with a pair of electrodes electrically connected to a sensing unit. The electrodes of one of the detection units attached to adjacent battery cells are joined together via a conductive junction, and all of the detection units are connected in series. The detection unit detects the deformation of the battery cell and / or the pressure applied to the battery cell caused by the expansion or contraction of the battery cell.

10. The battery unit according to claim 9, wherein the joint directly joins the opposing surfaces of the electrodes of the detection unit attached to adjacent battery cells.

11. It has multiple battery groups, Each of the aforementioned battery groups is, Multiple battery cells, Each of the aforementioned battery cells has the aforementioned detection unit attached to its outer peripheral surface, The battery unit according to claim 9, wherein in each of the battery groups, one electrode of the detection unit attached to an adjacent battery cell is joined to the other via the conductive junction, and all of the detection units are connected in series.

12. The battery unit according to claim 11, wherein each of the aforementioned battery groups is connected in parallel.

13. It further includes an abnormality detection unit and a circuit interruption unit, The abnormality determination unit determines whether each of the battery groups is abnormal based on the output of the detection unit connected in series with each of the battery groups. The battery unit according to claim 11 or 12, wherein the circuit interruption unit interrupts the battery group that has been determined to be abnormal based on the determination result of the abnormality determination unit.

14. The battery unit according to any one of claims 9 to 12, wherein each of the detection units has a label on the uppermost layer.

15. The battery unit according to claim 14, wherein the label displays information relating to the battery cell.

16. The battery unit according to claim 15, wherein the label displays information related to the detection unit.

17. The battery unit according to any one of claims 9 to 12, wherein the detection unit has a detection element that detects magnetic changes caused by deformation of the battery cell.

18. The aforementioned detection element includes a magnetic material, The battery unit according to claim 17, 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 deformation of the battery cell.

19. 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 17, wherein the detection element is a detection element that detects magnetic changes generated in the structure due to deformation of the battery cell.

20. The battery unit according to any one of claims 9 to 12, wherein the detection unit is a semiconductor strain gauge.

21. The battery unit according to any one of claims 9 to 12, wherein the detection unit is a capacitive pressure sensor.

22. The battery unit according to any one of claims 9 to 12, wherein the detection unit is an optical fiber strain gauge.

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