Battery cooling device

Abstract

To provide a battery cooling device having a plurality of battery cells, in which the expansion, etc. of the battery cells is detected with high sensitivity while maintaining heat conduction efficiency.SOLUTION: The present battery cooling device comprises a plurality of battery cells, a heat pipe, and a strain gauge, and the heat pipe includes a plurality of first extensions extending in a first direction and a plurality of second extensions extending in a second direction that intersects the first direction. The plurality of first extensions are arranged at a prescribed interval, and the ends of the adjacent first extensions are connected staggeredly by the second extensions, altogether constituting a jig-zag folded structure. The respective battery cells are arranged between the adjacent first extensions so as to contact the inner wall surfaces of the first extensions. The second extensions include a low elastic part whose electricity is lower than the first extensions, and the first extensions have higher thermal conductivity than that of the low elastic part, with the low elastic part constituting at least a section of the outer wall surface of the second extensions. The strain gauge is pasted to the low elastic part.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Battery cooling devices having a large number of battery cells are known. In such battery cooling devices, for example, a heat pipe is arranged in contact with the battery cells in order to cool the battery cells in a heated state due to charging and discharging. A working fluid is sealed inside the heat pipe, and heat exchange occurs by evaporation and condensation of the working fluid. In such battery cooling devices, a detection means for detecting the state of the battery cells may be provided (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 074456 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above-mentioned points, and has an object to detect expansion, etc. of a battery cell with high sensitivity while maintaining heat conduction efficiency in a battery cooling device having a plurality of battery cells. [Means for solving the problem]

[0005] This battery cooling device has a plurality of battery cells, a heat pipe, and a strain gauge, and the heat pipe includes a plurality of first extension portions extending in a first direction and a plurality of second extension portions extending in a second direction intersecting the first direction, and the plurality of first extension portions are arranged at a predetermined interval, and ends of adjacent first extension portions are alternately connected by the second extension portions, so that the overall structure is folded back in a zigzag pattern, and each of the battery cells is arranged between adjacent first extension portions so as to contact an inner wall surface of the first extension portion, and the second extension portion includes a low elasticity portion having a lower elasticity modulus than the first extension portion, and the first extension portion has a higher thermal conductivity than the low elasticity portion, and the low elasticity portion constitutes at least a part of the outer wall surface of the second extension portion, and the strain gauge is affixed to the low elasticity portion. Effect of the Invention

[0006] According to the disclosed technique, in a battery cooling device having a plurality of battery cells, it is possible to detect the expansion, etc. of the battery cells with high sensitivity while maintaining heat transfer efficiency. [Brief description of the drawings]

[0007] [Figure 1] 1 is a perspective view illustrating a battery cooling device according to a first embodiment; [Diagram 2] 1 is a diagram illustrating a battery cooling device according to a first embodiment. [Diagram 3] 1 is a partial cross-sectional view illustrating a battery cooling device according to a first embodiment. [Figure 4] FIG. 2 is a plan view illustrating the strain gauge according to the first embodiment. [Diagram 5] 1 is a cross-sectional view (part 1) illustrating a strain gauge according to a first embodiment. FIG. [Figure 6] 4 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. FIG. [Figure 7] 4 is a partial cross-sectional view illustrating a battery cooling device according to a first modified example of the first embodiment. FIG. [Figure 8]11 is a partial cross-sectional view illustrating a battery cooling device according to a second modified example of the first embodiment. FIG. [Figure 9] 11 is a partial cross-sectional view illustrating a battery cooling device according to a third modified example of the first embodiment. FIG. [Figure 10] 11 is a partial cross-sectional view illustrating a battery cooling device according to a fourth modified example of the first embodiment. FIG. [Figure 11] 11 is a schematic diagram illustrating a battery cooling device according to a second embodiment. FIG. [Figure 12] FIG. 4 is a diagram illustrating an example of an abnormality determination unit. [Figure 13] FIG. 2 is an example of a hardware block diagram of a control unit. [Figure 14] FIG. 11 is a diagram illustrating a battery cooling device according to a third embodiment. [Figure 15] 13 is a schematic diagram illustrating a battery cooling device according to a modified example of the third embodiment. FIG. [Figure 16] 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 fourth embodiment. [Figure 17] 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 fifth embodiment. [Figure 18] 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 fifth embodiment. [Figure 19] 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 fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the mode for carrying out the invention will be described with reference to the drawings. In each drawing, the same components may be given the same reference numerals. In addition, in each drawing, the X direction, Y direction, and Z direction, which are perpendicular to each other, may be defined. In this case, in the X direction, the starting point (root) side of the arrow may be called the X- side, and the ending point (arrowhead) side of the arrow may be called the X+ side. The same applies to the Y direction and the Z direction. In addition, in the description of each drawing, the description of the same components as those already described may be omitted.

[0009] First embodiment Fig. 1 is a perspective view illustrating a battery cooling device according to a first embodiment. Fig. 2 is a view illustrating the battery cooling device according to the first embodiment, in which the battery cooling device 1 is viewed from the direction of the arrow S in Fig. 1. Fig. 3 is a partial cross-sectional view illustrating the battery cooling device according to the first embodiment, showing a cross section cut in a direction passing through a strain gauge 100 and parallel to the XY plane. Note that the view of the battery cooling device from the direction of the arrow S may be referred to as a plan view.

[0010] 1 to 3, the battery cooling device 1 includes a plurality of battery cells 10, a heat pipe 20, and a strain gauge 100. The battery cooling device 1 can be used, for example, to supply power to an electric vehicle.

[0011] The battery cell 10 is, for example, cylindrical. The battery cell 10 may be, for example, polygonal prism-shaped such as a square prism. The battery cell 10 is, for example, a lithium ion battery. Although not shown in the drawings, the multiple battery cells 10 are connected in parallel or in series. In the example of FIGS. 1 to 3, the battery cooling device 1 has 64 battery cells 10, but the number of battery cells 10 is arbitrary.

[0012] The heat pipe 20 includes a plurality of first extension portions 21 extending in a first direction in a plan view, and a plurality of second extension portions 22 extending in a second direction intersecting the first direction. In the example of Figs. 1 to 3, the first direction is the Y direction, and the second direction is the X direction. In the example of Figs. 1 to 3, the first direction and the second direction are perpendicular to each other. However, the first direction and the second direction do not have to be perpendicular to each other.

[0013] The heat pipe 20 has a structure in which a plurality of first extension portions 21 are arranged at a predetermined interval in a plan view, and ends of adjacent first extension portions 21 are alternately connected by second extension portions 22, and the heat pipe 20 is folded back in a zigzag pattern as a whole. In the example of Figs. 1 to 3, the heat pipe 20 includes five first extension portions 21 and four second extension portions 22, but the numbers of the first extension portions 21 and second extension portions 22 are not limited thereto.

[0014] At the connection portion between the first extension portion 21 and the second extension portion 22, the first extension portion 21 and / or the second extension portion 22 may be curved along the outer circumferential surface of the battery cell 10. Moreover, the first extension portion 21 and the second extension portion 22 do not have to be flat, and may have an uneven structure along the outer circumferential surface of the battery cell 10, for example.

[0015] The second extension portion 22 includes a low elasticity portion constituting at least a part of the outer wall surface of the second extension portion 22. The low elasticity portion is a portion having a lower elasticity modulus than the first extension portion 21. The low elasticity portion has flexibility. In this embodiment, the entire second extension portion 22 is a low elasticity portion. That is, in this embodiment, the low elasticity portion constitutes the entire outer wall surface of the second extension portion 22. The elasticity modulus of the low elasticity portion is, for example, 5 GPa or less. In contrast, the elasticity modulus of the first extension portion 21 is, for example, 50 GPa or more. From the viewpoint of detecting micro-strain with high sensitivity, it is preferable that the elasticity modulus of the low elasticity portion is 1 / 10 or less of the elasticity modulus of the first extension portion 21.

[0016] In the heat pipe 20, the surface in contact with the battery cell 10 is referred to as the inner wall surface, and the surface opposite the inner wall surface and not in contact with the battery cell 10 is referred to as the outer wall surface. As described later, the heat pipe 20 has a cavity C, but the inner wall surface and the outer wall surface referred to here are not surfaces exposed in the cavity C.

[0017] The first extension portion 21 has a higher thermal conductivity than the low elasticity portion. That is, in this embodiment, the first extension portion 21 has a higher thermal conductivity than the second extension portion 22, which is a low elasticity portion entirely. The thermal conductivity of the first extension portion 21 is, for example, 200 W / m·k or more. In contrast, the thermal conductivity of the low elasticity portion is, for example, 0.5 W / m·k or less.

[0018] The first extension portion 21 is made of, for example, a metal. Examples of metals include materials with high thermal conductivity, such as copper, aluminum, and stainless steel. The low elasticity portion constituting the second extension portion 22 is made of, for example, a resin. Examples of resins include resins with high heat resistance, such as PI (polyimide) resin, PEEK (polyether ether ketone) resin, and PPS (polyphenylene sulfide) resin.

[0019] In the heat pipe 20, the first extension portions 21 and the second extension portions 22 arranged alternately are connected to form one continuous structure. The adjacent first extension portions 21 and second extension portions 22 are integrated together by, for example, adhesion or molding. A continuous cavity C is provided inside this continuous structure.

[0020] A working fluid (not shown) is sealed in the cavity C. For example, pure water, ethanol, etc. can be used as the working fluid. A capillary structure (wick) (not shown) is provided on the inner surface of the heat pipe 20 that defines the cavity C. The inside of the cavity C is, for example, in a vacuum state that contains nothing but the working fluid and its vapor, making it easy for the working fluid to evaporate and condense.

[0021] The heat pipe 20 is provided so as to be in contact with the outer peripheral surface of each battery cell 10. In detail, each battery cell 10 is disposed between adjacent first extension portions 21 so as to be in contact with the inner wall surface of the first extension portion 21. Every battery cell 10 is in contact with any one of the first extension portions 21. Some battery cells 10 are in contact with both the first extension portion 21 and the second extension portion 22.

[0022] 1 to 3, assuming that the X direction is the row direction and the Y direction is the column direction, 8 rows and 2 columns of battery cells 10 are arranged between adjacent first extension portions 21. Note that this is just an example, and the number of battery cells 10 arranged between adjacent first extension portions 21 is arbitrary.

[0023] When the heat pipe 20 receives heat from the battery cell 10, the working fluid in that area evaporates and turns into gas, absorbing the heat as latent heat and moving to the low-temperature area in the cavity C. The working fluid that moves to the low-temperature area condenses, releasing heat and returning to liquid. This allows the heat from the high-temperature area to be transported to the low-temperature area. The liquid working fluid also returns to the original heat source area due to the capillary action of the wick. The working fluid is continuously vaporized, liquefied, and moved, so heat exchange can continue for a long period of time.

[0024] The strain gauge 100 is a sensor that detects the expansion and contraction of the heat pipe 20 accompanying the expansion and contraction of the battery cell 10. The strain gauge 100 is an example of a detection unit in the present disclosure. The strain gauge 100 is attached to a low elasticity portion constituting the outer wall surface of each of the second extension portions 22. The strain gauge 100 may be attached to a part of the low elasticity portion constituting the outer wall surface of each of the second extension portions 22, or may be attached to the entirety of the low elasticity portion. Details of the strain gauge 100 will be described later.

[0025] For example, if the battery cell 10 expands or contracts for some reason, an external force is applied to the heat pipe 20 in contact with the battery cell 10, causing a small strain. If the entire heat pipe 20 were made of a highly rigid metal such as copper or aluminum, it would be difficult for the strain gauge 100 to detect the small strain of the heat pipe 20.

[0026] However, in the battery cooling device 1, the second extension portion 22 includes a low elasticity portion having a lower elasticity than the first extension portion 21, and the strain gauge 100 is attached to the low elasticity portion. Since the low elasticity portion has flexibility, it is more susceptible to distortion than the first extension portion 21. Therefore, the strain gauge 100 attached to the low elasticity portion can detect minute distortions of the heat pipe 20 with high sensitivity. In other words, the expansion of the battery cell 10 can be detected with high sensitivity.

[0027] That is, when any one or more of the multiple battery cells 10 expands, the resistance value of the strain gauge 100 attached to the heat pipe 20 increases. By monitoring this resistance value, information on the expansion of any one or more of the multiple battery cells 10 can be obtained. Furthermore, when any one or more of the multiple battery cells 10 contract, the resistance value of the strain gauge 100 attached to the heat pipe 20 decreases. By monitoring this resistance value, information on the contraction of any one or more of the multiple battery cells 10 can be obtained. Furthermore, the degree of expansion or contraction can be detected based on the degree of change in the resistance value of the output of each strain gauge 100.

[0028] Furthermore, in the battery cooling device 1, the first extension portion 21, which occupies a large portion of the heat pipe 20, is formed from a material having a higher thermal conductivity than the low elasticity portion, so that expansion of the battery cell 10, etc. can be detected with high sensitivity while maintaining thermal conduction efficiency.

[0029] [Strain gauge 100] Fig. 4 is a plan view illustrating the strain gauge according to the first embodiment. Fig. 5 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. 4.

[0030] 4 and 5, 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 FIGS. 4 and 5. First, each part constituting the strain gauge 100 will be described in detail.

[0031] In addition, in FIG. 4 and FIG. 5, 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, in FIG. 4 and FIG. 5, the plan view refers to viewing the object in the normal direction from the upper side to the lower side with respect to the upper surface 110a of the substrate 110. And, 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 low elasticity portion of the second extension portion 22 such that the lower surface 110b of the base material 110 faces the low elasticity portion side of the second extension portion 22.

[0032] 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 and the like. 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 low elasticity portion to the sensing portion 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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. 4 as having a dense matte pattern.

[0037] 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. 4), 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. 4).

[0038] 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.

[0039] 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).

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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).

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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. 4 as having a matte pattern with a lower density than the resistor 130.

[0049] 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. 4, the electrode 150 is shown with a matte pattern having the same density as the wiring 140 for convenience.

[0050] 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.

[0051] [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.

[0052] 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.

[0053] 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. 4.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 6 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. FIG. 6 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.

[0060] 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 electrodes 150, for example. However, the planar shapes of the functional layer 120, the resistor 130, the wiring 140, and the electrodes 150 do not have to 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 a shape different from the planar shapes of the resistor 130, the wiring 140, and the electrodes 150. In this case, the functional layer 120 may be patterned to be solid in the area where the resistor 130, the wiring 140, and the electrodes 150 are formed, for example. Alternatively, the functional layer 120 may be formed in a solid manner over the entire upper surface of the base material 110.

[0061] 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.

[0062] Modification of the First Embodiment In the modified example of the first embodiment, an example of a battery cooling device in which the structure of the portion where the strain gauge is attached is different is 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.

[0063] FIG. 7 is a partial cross-sectional view illustrating a battery cooling device according to a first modified example of the first embodiment, showing a cross section taken along a line passing through the strain gauge 100 and parallel to the XY plane.

[0064] 7, the battery cooling device 1A differs from the battery cooling device 1 in that the second extension portion 22 includes a high thermal conductivity portion 22a that is hollow and has a higher thermal conductivity than the low elasticity portion 22b, and a low elasticity portion 22b laminated on the high thermal conductivity portion 22a. The low elasticity portion 22b is laminated on the entire surface of the high thermal conductivity portion 22a. The low elasticity portion 22b is flexible.

[0065] The high thermal conductivity portion 22a is formed integrally with the first extension portion 21, for example, from the same metal as the first extension portion 21. The low elasticity portion 22b is bonded to the high thermal conductivity portion 22a, for example. The low elasticity portion 22b may be made of the resin exemplified as the material of the low elasticity portion in the first embodiment. The strain gauge 100 is attached to the low elasticity portion 22b forming the outer wall surface of the second extension portion 22.

[0066] In the battery cooling device 1A, since the strain gauge 100 is attached to the flexible low elasticity portion 22b, it is possible to detect minute strains of the heat pipe 20 by the strain gauge 100, as in the battery cooling device 1. In addition, in the battery cooling device 1A, since a larger portion of the heat pipe 20 is formed from a material with high thermal conductivity compared to the battery cooling device 1, it is possible to detect the expansion of the battery cell 10 with high sensitivity while maintaining better thermal conduction efficiency. In addition, in the battery cooling device 1A, since it is not necessary to perform processing such as hollowing out the high thermal conductivity portion 22a or connecting the high thermal conductivity portion 22a and the low elasticity portion 22b, it is only necessary to attach the low elasticity portion 22b equipped with the strain gauge 100 to the high thermal conductivity portion 22a, it is easy to manufacture.

[0067] FIG. 8 is a partial cross-sectional view illustrating a battery cooling device according to Modification 2 of the first embodiment, showing a cross section taken along a line passing through the strain gauge 100 and parallel to the XY plane.

[0068] 8, the battery cooling device 1B is different from the battery cooling device 1A in that the low elasticity portion 22b is laminated on a part of the surface of the high thermal conductivity portion 22a. That is, when viewed from the lamination direction of the high thermal conductivity portion 22a and the low elasticity portion 22b (viewed from the Y+ side to the Y- side), the size of the low elasticity portion 22b is smaller than the size of the high thermal conductivity portion 22a. That is, the outer wall surface of the second extension portion 22 is formed by the high thermal conductivity portion 22a and the low elasticity portion 22b.

[0069] In this way, it is not necessary to configure the entire outer wall surface of the second extension portion 22 with the low elasticity portion, and only the portion to which the strain gauge 100 is attached may be configured with the low elasticity portion. In the battery cooling device 1B, the battery cell 10 is completely covered with the high thermal conductivity portion 22a, so that the cooling performance is equivalent to that of the battery cooling device 1A shown in FIG. 7. In addition, in the battery cooling device 1B, as in the battery cooling device 1A, it is not necessary to perform processing such as hollowing out the high thermal conductivity portion 22a or connecting the high thermal conductivity portion 22a and the low elasticity portion 22b, and it is easy to manufacture because it is only necessary to attach the low elasticity portion 22b equipped with the strain gauge 100 to the high thermal conductivity portion 22a. In addition, in the battery cooling device 1B, the material of the low elasticity portion 22b can be reduced compared to the battery cooling device 1A.

[0070] FIG. 9 is a partial cross-sectional view illustrating a battery cooling device according to a third modification of the first embodiment, showing a cross section taken along a line passing through the strain gauge 100 and parallel to the XY plane.

[0071] 9, the battery cooling device 1C differs from the battery cooling device 1B in that the second extension portion 22 includes a high thermal conductivity portion 22a that is hollow and has a higher thermal conductivity than the low elasticity portion 22b, a through hole 22x formed in the high thermal conductivity portion 22a, and a low elasticity portion 22b filling the through hole 22x. When viewed from the Y+ side to the Y- side, the size of the low elasticity portion 22b is smaller than the size of the high thermal conductivity portion 22a. That is, the outer wall surface of the second extension portion 22 is formed by the high thermal conductivity portion 22a and the low elasticity portion 22b.

[0072] In this way, the through-holes 22x may be partially formed in the high thermal conductivity portion 22a, and the through-holes 22x may be filled with the low elasticity portion 22b. In the battery cooling device 1C, since the area of ​​the high thermal conductivity portion 22a is larger than the area of ​​the low elasticity portion 22b in the second extension portion 22, the cooling performance is inferior to that of the battery cooling device 1A shown in FIG. 7 and the battery cooling device 1B shown in FIG. 8, but is superior to that of the battery cooling device 1 shown in FIG. 3. In addition, by making the area of ​​the low elasticity portion 22b small, the original heat transfer efficiency of the heat pipe 20 can be maintained. In addition, in the battery cooling device 1C, it is possible to reduce the thickness and space as much as the battery cooling device 1.

[0073] FIG. 10 is a partial cross-sectional view illustrating a battery cooling device according to a fourth modified example of the first embodiment, showing a cross section taken along a line passing through the strain gauge 100 and parallel to the XY plane.

[0074] 10, the battery cooling device 1D differs from the battery cooling device 1 in that the second extension portion 22 includes a high thermal conductivity portion 22a that forms an inner wall surface and has a higher thermal conductivity than the low elasticity portion 22b, and a low elasticity portion 22b that forms an outer wall surface, and the high thermal conductivity portion 22a and the low elasticity portion 22b face each other across a cavity C. The low elasticity portion 22b is provided over the entire Z direction. That is, the outer wall surface of the second extension portion 22 is formed only by the low elasticity portion 22b.

[0075] In this manner, the inner wall surface and the outer wall surface of the second extension portion 22 may be made of different materials. In this case, the same effect as that of the battery cooling device 1 is obtained. Moreover, in the battery cooling device 1D, it is possible to achieve both sensitivity and heat transfer, and the degree of freedom in design can be improved.

[0076] Second Embodiment In the second embodiment, an example of a battery cooling device having an abnormality determination unit 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.

[0077] 11 is a schematic diagram illustrating a battery cooling device according to the second embodiment. As shown in FIG. 11, the battery cooling device 2 includes an abnormality determination unit 300 in addition to the configuration of the battery cooling device 1.

[0078] In the battery cooling device 2, the output of each strain gauge 100 is input to the abnormality determination unit 300. Note that, for simplification in Fig. 11, the connection between each strain gauge 100 and the abnormality determination unit 300 is shown by a single line, but in reality, a pair of electrodes 150 of each strain gauge 100 is connected to the abnormality determination unit 300.

[0079] The abnormality determination unit 300 can determine an abnormality in the battery cell 10 based on the output of each strain gauge 100, and output the determination result. Specifically, the abnormality determination unit 300 can monitor the resistance value of each strain gauge 100 to determine whether or not the heat pipe 20 has expanded or contracted due to the expansion or contraction of the battery cell 10, and output the determination result.

[0080] For example, when the resistance value of at least one of the strain gauges 100 exceeds a predetermined threshold value, the abnormality determination unit 300 can determine that expansion or contraction has occurred in any of the battery cells 10. In addition, the abnormality determination unit 300 can output the determination result to the outside.

[0081] Fig. 12 is a diagram illustrating an example of the abnormality determination section. As shown in Fig. 12, the abnormality determination section 300 can include, for example, an analog front-end section 310 and a control section 320. The output of each strain gauge 100 is connected to the analog front-end section 310.

[0082] 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 100. 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 using individual components.

[0083] The analog front-end unit 310 has bridge circuits corresponding to the number of strain gauges 100, but amplifiers and the like may be provided separately or may be common to both.

[0084] In the analog front-end unit 310, a strain waveform corresponding to the output of each strain gauge 100 is output from the bridge circuit, amplified by an amplifier circuit, converted into a digital signal by an A / D conversion circuit, and output to the control unit 320. If the analog front-end unit 310 is equipped with a temperature compensation circuit, a temperature compensated digital signal is sent to the control unit 320.

[0085] 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 cell 10. The arithmetic processing includes, for example, comparing the distortion waveform with a predetermined threshold value. The control unit 320 can output a control signal OP based on the result of the arithmetic processing.

[0086] The control signal OP can be input to, for example, an audio output device, an image display device, a light flashing device, etc. These devices can notify a person monitoring the device, etc. of an abnormality in the battery cooling device 2 by issuing a warning sound, a warning image, a warning light flashing, etc.

[0087] Fig. 13 is an example of a hardware block diagram of the control unit. As shown in Fig. 13, 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.

[0088] 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.

[0089] 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.

[0090] In this way, by providing the abnormality determination unit 300 in the battery cooling device 2, the degree of expansion and contraction of the heat pipe 20 accompanying the expansion and contraction of the battery cell 10 can be detected as a change in the resistance value of the resistor of the strain gauge 100. Then, when an abnormality occurs, the abnormality of the battery cooling device 2 can be notified to a person monitoring the device, etc., based on the control signal output by the abnormality determination unit 300. This makes it possible to avoid damage to the battery cell 10 and improve the safety of the battery cooling device 2.

[0091] In particular, when the 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 the resistor 130 is formed from Cu-Ni or Ni-Cr. When the 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 the resistor 130 is formed from Cu-Ni or Ni-Cr. Therefore, by forming the resistor 130 from a Cr mixed phase film, it becomes possible to accurately detect the expansion and contraction of the battery cell 10.

[0092] Third embodiment In the third embodiment, an example of a battery cooling device having a cooling unit will be described. Note that in the third embodiment, the description of the same components as those in the embodiments already described may be omitted.

[0093] FIG. 14 is a diagram illustrating a battery cooling device according to the third embodiment, and is a diagram in which the battery cooling device 1 is viewed from the same direction as the direction of the arrow S in FIG.

[0094] As shown in FIG. 14, the battery cooling device 3 further includes a cooling section 50 in contact with the heat pipe 20, and differs from the battery cooling device 1 in that a strain gauge 100 is attached to the cooling section 50.

[0095] The cooling unit 50 is disposed so as to be in contact with a region of the heat pipe 20 that is not in contact with the battery cell 10. The cooling unit 50 is a part that dissipates heat transferred from the heat pipe 20 to the outside. The cooling unit 50 is, for example, a heat dissipation fin or a heat sink. The cooling unit 50 may be, for example, a radiator mounted on a vehicle.

[0096] For example, if the heat pipe 20 is damaged for some reason or stops working, the working fluid will no longer circulate through the cavity C, causing the entire heat pipe 20 to heat up more than usual, and as a result, the cooling part 50 will also heat up more than usual. This temperature rise causes micro-distortion in the cooling part 50, and by detecting the micro-distortion with the strain gauge 100 attached to the cooling part 50, the degree of temperature rise in the cooling part 50 can be detected.

[0097] When the cooling section 50 has high rigidity, it is preferable to provide a low elasticity section in the cooling section 50 and attach the strain gauge 100 to the low elasticity section, as in the first embodiment. This makes it possible to detect minute strains in the cooling section 50 with high sensitivity.

[0098] Modification of the third embodiment In the modified example of the third embodiment, an example is shown in which a battery cooling device having a cooling unit further has an abnormality determination unit. Note that in the modified example of the third embodiment, the description of the same components as those in the already described embodiment may be omitted.

[0099] Fig. 15 is a schematic diagram illustrating a battery cooling device according to a modified example of the third embodiment. As shown in Fig. 15, the battery cooling device 3A has, in addition to the configuration of the battery cooling device 3, an abnormality determination unit 300A.

[0100] In the battery cooling device 3A, the output of each strain gauge 100 attached to the heat pipe 20 and the output of the strain gauge 100 attached to the cooling unit 50 are input to the abnormality determination unit 300A. Note that, for the sake of simplicity, in Fig. 15, the connection between each strain gauge 100 and the abnormality determination unit 300A is shown by a single line, but in reality, a pair of electrodes 150 of each strain gauge 100 is connected to the abnormality determination unit 300A.

[0101] In the abnormality determination section 300A, the configuration shown in FIG. 12 and FIG. 13 is similar to that of the abnormality determination section 300, and therefore the description thereof will be omitted.

[0102] The abnormality determination unit 300A can determine an abnormality in the battery cell 10 based on the output of each strain gauge attached to the heat pipe 20, and output a first determination result. The abnormality determination unit 300A can also determine an abnormality in the heat pipe 20 based on the output of the strain gauge attached to the cooling unit 50, and output a second determination result. This will be specifically described below.

[0103] Like the abnormality determination unit 300, the abnormality determination unit 300A can detect expansion and contraction of the heat pipe 20 based on the output of each strain gauge 100 attached to the heat pipe 20. Furthermore, the abnormality determination unit 300A can detect an excessive temperature rise of the heat pipe 20 based on the output of the strain gauge 100 attached to the cooling unit 50.

[0104] As described above, if the heat pipe 20 is damaged or stops working for some reason, the working fluid will no longer circulate through the cavity C, causing the entire heat pipe 20 to heat up more than usual, and as a result, the cooling unit 50 will also heat up more than usual. The abnormality determination unit 300A can detect this temperature rise based on the output of the strain gauge 100 attached to the cooling unit 50.

[0105] This makes it possible to know whether the expansion and contraction of the heat pipe 20 detected by each strain gauge 100 attached to the heat pipe 20 is deformation due to expansion and contraction of the battery cell 10 or deformation due to an abnormality in the heat pipe 20.

[0106] For example, the abnormality determination unit 300A may detect an abnormality in the expansion and contraction of the heat pipe 20 based on the output of the strain gauge 100 attached to the heat pipe 20, and may also detect an abnormality in the temperature rise of the heat pipe 20 based on the output of the strain gauge 100 attached to the cooling unit 50. In this case, the abnormality determination unit 300A can notify a supervisor of the device of information such as "the working fluid is not flowing properly" by outputting a control signal to an image display device or the like.

[0107] Furthermore, the abnormality determination unit 300A may detect an abnormality in the expansion and contraction of the heat pipe 20 based on the output of the strain gauge 100 attached to the heat pipe 20, and may determine that the output of the strain gauge 100 attached to the cooling unit 50 is normal. In this case, the abnormality determination unit 300A can notify a supervisor of the device of information such as "battery cell replacement is necessary" by outputting a control signal to an image display device or the like.

[0108] Furthermore, the abnormality determination unit 300A can determine that the battery cooling device 3A is in a dangerous state when the output of the strain gauge 100 attached to the heat pipe 20 and the output of the strain gauge 100 attached to the cooling unit 50 greatly exceed a predetermined threshold value. In this case, the abnormality determination unit 300A can notify a person monitoring the device, etc., of information such as "it is in a dangerous state" by outputting a control signal to an image display device, etc.

[0109] Fourth embodiment In the above-mentioned 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-mentioned 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 the strain body, such as the low elasticity part of the heat pipe 20) by a detection element included in the strain gauge.

[0110] 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 fourth embodiment, a strain gauge including a detection element utilizing the Villari phenomenon will be described. Also, in the fifth embodiment, a strain gauge including a detection element having a magnetic tunnel junction structure will be described.

[0111] In each embodiment of this specification, members having similar functions are given similar names and numbers, and the description will not be repeated. In addition, the directions of the x-axis, y-axis, and z-axis in each drawing (drawings from FIG. 16 onward) relating to each embodiment are the same. 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. However, since the strain gauge 100 is attached to the heat pipe 20 in various directions, the directions of the x-axis, y-axis, and z-axis in the drawings from FIG. 16 onward do not match the directions of the x-axis, y-axis, and z-axis in the drawings before FIG. 16.

[0112] FIG. 16 is a diagram showing an example of a detection element 600 included in a strain gauge according to the fourth embodiment. FIG. 16(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. 16(b) shows a cross-sectional view of the detection element 600 shown in FIG. 16(a) along line α-α'. Note that, in FIG. 16(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.

[0113] As shown in FIG. 16(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.

[0114] 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.

[0115] The configuration of the detection element 600 will be further described with reference to the cross-sectional view of Fig. 16(b). In Fig. 16(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 Fig. 16(b) are connected to surround the base metal 670.

[0116] 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. 16(b).

[0117] 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.

[0118] One surface of the detection element 600 may be attached to the substrate 110 as shown in FIG. 16(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 low elasticity portion of the heat pipe 20 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. 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 low elasticity portion of the heat pipe 20 without providing the substrate 110.

[0119] The low elasticity portion of the heat pipe 20 according to this embodiment may basically be of the same configuration and material as the low elasticity portion of the heat pipe 20 according to the first embodiment.

[0120] 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 body. When an alternating current is supplied from a power source to the driving coil 620, the driving coil 620 generates an alternating magnetic field around it. This generates a magnetic field, and the base metal 670 is magnetized. When the low elasticity portion of the heat pipe 20 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 low elasticity portion of the heat pipe 20 without the substrate 110, stress is transmitted directly from the low elasticity portion of the heat pipe 20 to the base metal 670 (and the insulating layers 640 to 660 covering it).

[0121] 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 distortion of the low elasticity part of the heat pipe 20 can be specified from the calculated stress. Note that when the detection element 600 has the shape shown in (a) and (b) of FIG. 16, the grid direction of the detection element 600 is equal to the α-α' direction in (a) of FIG. 16. Based on the principle described above, the detection element 600 can detect the distortion of the low elasticity part of the heat pipe 20. That is, the sensing element 600 functions as a sensing element of a strain gauge.

[0122] 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.

[0123] 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.

[0124] In addition, when the base metal 670 is substantially flat, 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. 16, both ends of the base metal 670 in the x direction do not need to be covered with the insulating layer 660.

[0125] In the battery cooling device according to this embodiment, when the low elasticity portion of the heat pipe 20 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.

[0126] The strain gauge including the detection element 600 according to this embodiment can be arranged in the low elasticity portion of the heat pipe 20 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 low elasticity portion of the heat pipe 20 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.

[0127] Fifth embodiment FIG. 17 is a diagram showing a detection element 700, which is an example of a detection element included in the strain gauge according to the fifth embodiment. FIG. 18 is a diagram showing a detection element 800, which is another example of the detection element according to the fifth embodiment. FIG. 19 is a diagram showing a detection element 900, which is yet another example of the detection element according to the fifth embodiment. (a) of FIG. 17 to 19 is a perspective view of the detection elements 700, 800, and 900, respectively. (b) of FIG. 17 to 19 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. 17 to 19 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. 17 to 19. 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.

[0128] As shown in (a) of Figures 17 to 19, 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.

[0129] 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 low elasticity portion of the heat pipe 20 via the substrate. The detection elements 700, 800, and 900 may be flat or thin-film detection elements as a whole. When the detection elements 700, 800, and 900 are flat or thin-film, the detection elements 700, 800, and 900 can be more easily attached to the substrate or the low elasticity portion of the heat pipe 20. For example, the lower surfaces of the detection elements 700, 800, and 900 may be directly attached to the low elasticity portion of the heat pipe 20 for use.

[0130] 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.

[0131] 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. 17 to 19, a current flows from the upstream electrode 710 to the downstream electrode 720. For example, in the case of FIG. 17(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) over the insulating film 740 to the lower magnetic film 730 (the negative z-axis side). 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. 17 to 19, 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.

[0132] However, when 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 low elasticity part of the heat pipe 20, the strain applied to the low elasticity part of the heat pipe 20 can be measured.

[0133] The detection element having the magnetic tunnel junction structure is not limited to the example shown in FIG. 17. For example, detection elements 800 and 900 shown in FIG. 18 and FIG. 19 can be adopted. The detection element 800 shown in FIG. 18 and the detection element 900 shown in FIG. 19 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. 17 to FIG. 19, respectively. As shown in the figure, the detection element 800 shown in FIG. 18 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. 19 is attached to a base material 110 via a substrate 910. As shown in Figs. 17 to 19, 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.

[0134] The low elasticity part of the heat pipe 20 according to this embodiment may basically have the same configuration and material as the low elasticity part of the heat pipe 20 according to the first embodiment. Moreover, the detection elements 700, 800, and 900 may have a substantially flat shape such as a film type as the whole element. This allows the detection element 700 to be easily attached to the low elasticity part of the heat pipe 20. Moreover, 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 the driving coil. By applying a magnetic field to the structural part of the magnetic tunnel junction, the above-mentioned tunnel magnetoresistance effect can be measured more stably, and therefore the strain can be detected stably.

[0135] 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. 17 to 19 may be designed so that the current flows from the downstream electrode 720 to the upstream electrode 710.

[0136] In the battery cooling device according to this embodiment, when the low elasticity portion of the heat pipe 20 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.

[0137] The strain gauge including the detection elements 700, 800, and 900 according to this embodiment can be arranged in the low elasticity portion of the heat pipe 20 at any of the arrangement positions 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 low elasticity portion of the heat pipe 20 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.

[0138] Sixth 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.

[0139] (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.

[0140] It is known that when stress is applied to a semiconductor, distortion occurs 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, like an electrical resistance-type metal strain gauge, can be directly attached to the low elasticity portion of the heat pipe 20 for use. In this case, when the low elasticity portion of the heat pipe 20 expands or contracts, the strain electrical resistance of the attached semiconductor (more specifically, the crystal lattice of the semiconductor) changes. Therefore, the amount of distortion in the low elasticity portion of the heat pipe 20 can be identified by measuring the electrical resistance.

[0141] 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 low elasticity portion of the heat pipe 20) can be identified by measuring the electrical resistance.

[0142] (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).

[0143] 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.

[0144] (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.

[0145] An optical fiber having such characteristics is attached to the low elasticity part of the heat pipe 20, and the amount of strain in the optical fiber (i.e., the amount of strain in the low elasticity part of the heat pipe 20) can be determined by measuring the wavelength spectrum of the reflected light of the optical fiber. 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.

[0146] (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.

[0147] (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 the low elasticity part of the heat pipe 20 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.

[0148] In either case, when the low elasticity portion of the heat pipe 20 is distorted, the pressure is transmitted directly or indirectly to the oscillator, generating an axial force in the oscillator. The natural frequency of the oscillator changes according to the axial force. Therefore, by measuring the natural frequency of the oscillator, the magnitude of the pressure on the low elasticity portion of the heat pipe 20 can be determined.

[0149] (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.

[0150] The 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 the piezoelectric pressure sensor to the low elasticity portion of the heat pipe 20, the amount of strain of the low elasticity portion of the heat pipe 20 can be determined.

[0151] 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.

[0152] The preferred embodiments and the like have been described above in detail. However, the battery cooling device 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 cooling device according to the above-described embodiments and the like without departing from the scope of the claims. [Explanation of symbols]

[0153] 1, 1A, 1B, 1C, 1D, 2, 3, 3A Battery cooling device, 10 Battery cell, 21 First extension portion, 22 Second extension portion, 22a High thermal conductivity portion, 22b Low elasticity portion, 22x Through hole, 50 Cooling portion, 100 Strain gauge, 110 Base material, 110a Upper surface, 120 Functional layer, 130 Resistor, 130e1, 130e2 Termination, 140 Wiring, 150 Electrode, 160 Cover layer, 300 Abnormality determination portion, 310 Analog front end portion, 320 Control portion, 321 CPU, 322 ROM, 323 RAM, 324 I / F, 325 Bus line, 600, 700, 800, 900 Detection element, 610 Base layer, 620 Drive 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. a plurality of battery cells, a heat pipe, and a strain gauge; the heat pipe includes a plurality of first extension portions extending in a first direction and a plurality of second extension portions extending in a second direction intersecting the first direction, the plurality of first extension portions are arranged at predetermined intervals, and ends of adjacent first extension portions are alternately connected by the second extension portions, forming a zigzag folded structure as a whole; Each of the battery cells is disposed between adjacent first extension portions so as to be in contact with an inner wall surface of the first extension portion, the second stretched portion includes a low elasticity portion having a lower elastic modulus than the first stretched portion, the first extension portion has a higher thermal conductivity than the low elasticity portion, the low elasticity portion constitutes at least a part of the outer wall surface of the second extension portion, The strain gauge is attached to the low elasticity portion.

2. the first extension portion is formed from metal, The battery cooling device according to claim 1 , wherein the low-elasticity portion is made of resin.

3. The battery cooling device according to claim 1 , wherein the entire second extension portion is the low-elasticity portion.

4. 2. The battery cooling device according to claim 1, wherein the second extension portion includes a high thermal conductivity portion that is hollow inside and has a higher thermal conductivity than the low elasticity portion, and the low elasticity portion is stacked on the high thermal conductivity portion.

5. 2. The battery cooling device of claim 1, wherein the second extension portion includes a high thermal conductivity portion that is hollow inside and has a higher thermal conductivity than the low elasticity portion, a through hole formed in the high thermal conductivity portion, and the low elasticity portion that fills the through hole.

6. Old claim 6 The battery cooling device according to claim 4 , wherein the low elasticity portion is smaller in size than the high thermal conductivity portion when viewed in a stacking direction of the high thermal conductivity portion and the low elasticity portion.

7. 2. The battery cooling device of claim 1, wherein the second extension portion includes a high thermal conductivity portion that forms an inner wall surface and has a higher thermal conductivity than the low elasticity portion, and the low elasticity portion that forms an outer wall surface, and the high thermal conductivity portion and the low elasticity portion face each other across a cavity.

8. : Old claim 8 The battery cooling device according to claim 4 , wherein the high thermal conductivity portion is made of metal.

9. : Old claim 9 The device further includes an abnormality determination unit, 8. The battery cooling device according to claim 1, wherein the abnormality determination unit determines an abnormality in the battery cell based on an output of each of the strain gauges, and outputs a determination result.

10. a cooling portion in contact with a region of the heat pipe that is not in contact with the battery cell; The battery cooling device according to claim 1 , wherein a second strain gauge is attached to the cooling portion.

11. The device further includes an abnormality determination unit, 11. The battery cooling device according to claim 10, wherein the abnormality determination unit determines an abnormality in the battery cell based on an output of each of the strain gauges and outputs a first determination result, and determines an abnormality in the heat pipe based on an output of the second strain gauge and outputs a second determination result.

12. The battery includes a plurality of battery cells, a heat pipe, and a detection unit. the heat pipe includes a plurality of first extension portions extending in a first direction and a plurality of second extension portions extending in a second direction intersecting the first direction, the plurality of first extension portions are arranged at predetermined intervals, and ends of adjacent first extension portions are alternately connected by the second extension portions, forming a zigzag folded structure as a whole; Each of the battery cells is disposed between adjacent first extension portions so as to be in contact with an inner wall surface of the first extension portion, the second stretched portion includes a low elasticity portion having a lower elastic modulus than the first stretched portion, the first extension portion has a higher thermal conductivity than the low elasticity portion, the low elasticity portion constitutes at least a part of the outer wall surface of the second extension portion, the detection unit is attached to the low elasticity unit, The detection unit detects deformation of the low-elasticity portion and / or pressure acting on the low-elasticity portion caused by expansion or contraction of the battery cell.

13. the first extension portion is formed from metal, The battery cooling device according to claim 12, wherein the low-elasticity portion is made of resin.

14. The battery cooling device according to claim 12 , wherein the entire second extension portion is the low-elasticity portion.

15. 13. The battery cooling device according to claim 12, wherein the second extension portion includes a high thermal conductivity portion that is hollow inside and has a higher thermal conductivity than the low elasticity portion, and the low elasticity portion is stacked on the high thermal conductivity portion.

16. 13. The battery cooling device of claim 12, wherein the second extension portion includes a high thermal conductivity portion that is hollow inside and has a higher thermal conductivity than the low elasticity portion, a through hole formed in the high thermal conductivity portion, and the low elasticity portion that fills the through hole.

17. The battery cooling device according to claim 15 or 16, wherein a size of the low elasticity portion is smaller than a size of the high thermal conductivity portion when viewed from a stacking direction of the high thermal conductivity portion and the low elasticity portion.

18. 13. The battery cooling device of claim 12, wherein the second extension portion includes a high thermal conductivity portion that forms an inner wall surface and has a higher thermal conductivity than the low elasticity portion, and the low elasticity portion that forms an outer wall surface, and the high thermal conductivity portion and the low elasticity portion face each other across a cavity.

19. 19. The battery cooling device according to claim 15, wherein the high thermal conductivity portion is made of metal.

20. The device further includes an abnormality determination unit, 19. The battery cooling device according to claim 12, wherein the abnormality determination unit determines an abnormality in the battery cell based on an output of each of the detection units, and outputs a determination result.

21. a cooling portion in contact with a region of the heat pipe that is not in contact with the battery cell; The battery cooling device according to claim 12 , wherein a second detection unit is attached to the cooling unit.

22. The device further includes an abnormality determination unit, 22. The battery cooling device of claim 21, wherein the abnormality determination unit determines an abnormality in the battery cell based on the output of each of the detection units and outputs a first determination result, and determines an abnormality in the heat pipe based on the output of the second detection unit and outputs a second determination result.

23. 19. The battery cooling device according to claim 12, wherein the detection unit includes a detection element that detects a magnetic change caused by deformation of the low-elasticity portion.

24. the detection element includes a magnetic material, 24. The battery cooling device according to claim 23, wherein the detection element detects a change in intensity of magnetization of the magnetic body when pressure is applied to the magnetic body due to deformation of the low-elasticity portion.

25. the detection element includes a magnetic tunnel junction structure in which an insulating film is sandwiched between magnetic films, The battery cooling device according to claim 23 , wherein the detection element detects a magnetic change occurring in the structure due to deformation of the low-elasticity portion.

26. 19. The battery cooling device according to claim 12, wherein the detection unit is a semiconductor strain gauge.

27. 19. The battery cooling device according to claim 12, wherein the detection unit is a capacitance type pressure sensor.

28. 19. The battery cooling device according to claim 12, wherein the detection unit is an optical fiber strain gauge.

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