Battery pack structure

Abstract

To suppress the temperature rise and deformation of a housing when a battery cell releases high-temperature gas.SOLUTION: A battery pack structure includes a facing wall portion at least facing a gas discharge portion in a housing, a fiber reinforced resin layer that reinforces at least a part of the wall portion surrounding one or more battery cells in the housing and the facing wall portion, and a thermal expansion portion that is arranged in the layer closest to the gas discharge portion of the facing wall portion and expands by absorbing the heat of the gas released from the gas discharge portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The following Patent Document 1 discloses a battery pack having a battery, a case for housing the battery, and a thermal expansion part capable of reducing the internal gap between the battery and the case in response to the application of heat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2008-152803 publication Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a battery cell in a battery pack releases high-temperature gas, the heat of the gas can be transferred to the battery pack housing, causing the temperature of the housing to rise. Furthermore, the release of gas can increase the pressure inside the housing, which can cause the housing to receive pressure from the inside and deform.

[0005] An object of the present invention is to suppress the temperature rise and deformation of the casing when the battery cell releases high-temperature gas. [Means for solving the problem]

[0006] In a battery pack structure according to one embodiment of the present invention, the opposing wall portion of the housing that faces at least the gas release portion includes at least a portion of the wall portion that surrounds one or more battery cells of the housing, a fiber-reinforced resin layer that reinforces the opposing wall portion, and a thermal expansion portion that is disposed in the layer of the opposing wall closest to the gas release portion and expands by absorbing heat from the gas released from the gas release portion. Effect of the Invention

[0007] According to the present invention, it is possible to suppress the temperature rise and deformation of the housing when the battery cell releases high-temperature gas. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view of a battery pack according to an embodiment, seen from above and on the front left. FIG. [Diagram 2] 2 is an exploded perspective view illustrating the structure of the battery pack illustrated in FIG. 1. [Diagram 3] 1 is a perspective view of a battery cell in a battery pack structure according to an embodiment, viewed from above and on the front left. FIG. [Figure 4] 3 is a schematic partial cross-sectional view taken along line AA in FIG. 2, showing the arrangement of a wall portion, a fiber-reinforced resin layer, and a thermal expansion portion in the battery pack structure according to the first embodiment. [Diagram 5] FIG. 5 is a diagram for explaining the function of the battery pack structure according to the first embodiment, and is a schematic partial cross-sectional view showing the state after gas has been released from the gas release portion of the battery cell in the cross-section shown in FIG. [Figure 6] 5 is a schematic partial cross-sectional view corresponding to FIG. 4, showing the arrangement relationship of a wall portion, a fiber-reinforced resin layer, and a thermal expansion portion in a battery pack structure according to a modified example of the first embodiment. FIG. [Figure 7] 5 is a schematic partial cross-sectional view corresponding to FIG. 4, showing the arrangement relationship of a wall portion, a fiber-reinforced resin layer, and a thermal expansion portion in a battery pack structure according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the battery pack structure according to the embodiment will be described with reference to the drawings. In each drawing, FR and RR indicate the front and rear in the vehicle longitudinal direction, respectively, LH and RH indicate the left and right in the vehicle width direction, and UP and DN indicate the upper and lower in the vehicle vertical direction, respectively. In the following description, the front and rear in the vehicle longitudinal direction, the upper and lower in the vehicle vertical direction, and the left and right in the vehicle lateral direction are simply referred to as "vehicle front", "vehicle rear", "vehicle upper", "vehicle lower", "vehicle left", and "vehicle right", respectively. Elements having the same function are given the same reference numerals, and duplicated descriptions are omitted.

[0010] The battery pack 1 according to the embodiment is used as a vehicle driving battery for a vehicle, such as an electric vehicle (EV) driven by an electric motor (not shown).

[0011] The battery pack structure according to the embodiment includes a housing 10, a battery cell 22, and an opposing wall portion 15 of the housing 10, as shown in FIGS.

[0012] The housing 10 is a rectangular box-shaped hollow member that houses the battery module 20 therein, and forms the exterior of the battery pack 1. The housing 10 has a flat shape in which the dimensions in the vehicle vertical direction are smaller than the dimensions in the vehicle front-rear direction or the vehicle left-right direction. The housing 10 has a wall portion 10a that forms the exterior of the battery pack 1, and the battery module 20 includes one or more battery cells 22. Thus, the housing 10 houses one or more battery cells 22. In the illustrated example, the wall portion 10a of the housing 10 surrounds the battery module 20 above, below, left, and right of the battery module 20. In other words, the housing 10 has a wall portion 10a that surrounds one or more battery cells 22. The shape of the housing 10 can be set appropriately according to the shape and dimensions of the battery pack 1, the arrangement method in the vehicle, and the like.

[0013] 2, the housing 10 includes an upper casing 11 and a lower casing 12. The upper casing 11 and the lower casing 12 are fastened to each other at their peripheries by fasteners such as bolts (not shown). A seal member made of a rubber material or the like may be interposed at the contact portion between the upper casing 11 and the lower casing 12.

[0014] The lower casing 12 is a box-shaped member with a bottom that is open toward the top of the vehicle, and has a generally rectangular shape in a plan view. The battery modules 20 are disposed at the bottom of the lower casing 12. In the illustrated example, the battery modules 20 are disposed in two rows in the vehicle width direction and four rows in the vehicle front-rear direction, totaling eight, in the region on the vehicle front side of the lower casing 12. Also, the battery modules 20 are stacked vertically in two tiers in the region on the vehicle rear side of the lower casing 12, totaling eight two-tiered battery modules 20 disposed in two rows in the vehicle width direction and two rows in the vehicle front-rear direction.

[0015] Furthermore, when multiple battery modules 20 are arranged, a partition 50 may be provided to divide the bottom of the lower casing 12 so as to separate the battery modules 20 from each other. In this manner, the positions of the battery modules 20 inside the housing 10 are fixed, so that movement of the battery modules 20 when an external force is applied to the battery pack 1 is restricted, and contact between the battery modules 20 can be suppressed. In the illustrated example, wiring members (not shown) such as bus bars that electrically connect the battery modules to each other are arranged between the battery module 20 arranged on the left side of the vehicle and the battery module 20 arranged on the right side of the vehicle.

[0016] The upper casing 11 is a plate-like member having a substantially rectangular shape in a plan view. The upper casing 11 closes the opening of the lower casing 12 above the vehicle, thereby sealing the inside of the housing 10. In the illustrated example, the region on the vehicle rear side of the upper casing 11 is formed to protrude toward the vehicle upper side more than the region on the vehicle front side according to the number of stages of the battery modules 20 arranged in the lower casing 12. In this way, a space for arranging more battery modules 20 on the vehicle rear side can be formed. This makes it possible to secure more battery capacity while making the battery pack 1 thinner as a whole and saving space.

[0017] The upper casing 11 or the lower casing 12 is molded, for example, by pressure molding a molding material. In one embodiment, the molding material may be a sheet molding compound (SMC) made by impregnating glass fibers with resin and molding them into a sheet. For example, the upper casing 11 or the lower casing 12 can be molded by stacking a plurality of SMC molding materials cut to a desired size in a mold and heating and pressure molding the SMC. Thus, the wall 10a of the housing 10 may be formed by pressure molding the SMC.

[0018] In this manner, the battery pack 1 is constructed by disposing the battery cells 22 in the lower casing 12 and covering it from above with the upper casing 11. The battery pack 1 constructed in this manner is fixed in the vehicle, for example, by fastening the peripheral portion of the housing 10 to the bottom of the vehicle body (not shown) via fasteners (not shown) such as bolts.

[0019] 1 and 2, the housing 10 houses a plurality of battery modules 20 therein, but is not limited to this. The number of battery modules 20 can be set according to the dimensions of the battery pack 1, or the dimensions or installation method of the battery modules 20. Thus, the number of battery modules 20 may be one or more.

[0020] 3, the battery module 20 is a modularized component in which multiple flat battery cells 22, whose width dimension is shorter than their longitudinal dimension, are arranged in parallel in the vehicle width direction. The electrode tabs (not shown) of the multiple battery cells 22 are arranged in a state in which they are electrically connected to each other by wiring members such as a bus bar unit (not shown). The anode terminal and cathode terminal (neither shown) of the battery cells 22 are exposed to the outside on the outer circumferential surface of the battery module 20 via the bus bar unit.

[0021] In the illustrated example, the battery module 20 includes a plurality of battery cells 22, but may include a single battery cell 22. In other words, the battery module 20 may house one or more battery cells. The battery module 20 may also include a module case that integrally houses the plurality of battery cells 22 and serves as an exterior member of the battery module 20.

[0022] The battery cell 22 is configured by, for example, sealing a power generating element, in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, together with an electrolyte, in an exterior member such as an aluminum can. In one embodiment, the battery cell 22 is a lithium ion secondary battery.

[0023] One or more battery cells 22 each have a gas release section 25 on an upper surface thereof that releases gas toward the top of the vehicle. The gas release section 25 releases gas when gas is generated inside the battery cell 22. The gas release section 25 may be, for example, an explosion-proof valve that opens to release the gas when the internal pressure of the battery cell 22 reaches or exceeds a predetermined pressure, or a seal member that breaks to release the gas.

[0024] In the illustrated example, the gas release section 25 has a substantially circular shape in a plan view, but may have, for example, a substantially elliptical, rectangular, or polygonal shape in a plan view. The position of the gas release section 25 can be appropriately set according to the shape and dimensions of the battery pack 1, the arrangement method of the battery cells 22, and the like. For example, the gas release section 25 may be set on the lower surface or side surface of the battery cell 22.

[0025] 1 and 2, an opposing wall portion 15 is provided in at least a region of the housing 10 facing the gas release portion 25 in the gas release direction. The opposing wall portion 15 is a region provided in a wall portion 10a above the vehicle of the upper casing 11 (housing 10) and having a substantially rectangular shape extending in the vehicle width direction in a plan view.

[0026] The position of the opposing wall portion 15 can be set according to the position of the gas release portion 25. For example, when the gas release portion 25 is provided on the side surface of the battery cell 22, the opposing wall portion 15 may be set on the side portion of the housing 10.

[0027] In the illustrated example, the battery cells 22 are arranged in parallel in the vehicle width direction, so that the gas discharge portions 25 are arranged in a substantially linear fashion in the vehicle width direction. Therefore, the opposing wall portion 15 extends in the vehicle width direction from the vehicle left end to the vehicle right end of the wall portion 10a so as to cover the gas discharge portions 25 arranged in a substantially linear fashion. The opposing wall portion 15 may extend in the vehicle front-rear direction from the vehicle front end to the vehicle rear end of the wall portion 10a. In other words, the opposing wall portion 15 may extend continuously from one end to the other end of the wall portion 10a of the housing 10.

[0028] 4 and 6 to 7, the opposing wall portion 15 includes at least a portion of the wall portion 10a that surrounds one or more battery cells 22 in the housing 10, a fiber reinforced resin layer 30, and a thermal expansion portion 45. In addition to the wall portion 10a, the fiber reinforced resin layer 30, and the thermal expansion portion 45, the opposing wall portion 15 may also include, as appropriate, for example, an adhesive layer for joining the wall portion 10a and the fiber reinforced resin layer 30, a resin layer 40a including the thermal expansion portion 45, and the like.

[0029] The fiber reinforced resin layer 30 is formed by arranging an FRP material composed of a plurality of reinforced fiber layers (not shown) stacked in the thickness direction and matrix resin 40b impregnated in the reinforced fiber layers, on the wall portion 10a.

[0030] The reinforcing fiber layer is made of reinforcing fiber bundles that are aligned in one direction or at different angles, stacked, and bound with stitch thread, or that are shaped by heat fusion without using stitch thread, or made of a woven fabric of reinforcing fibers. The reinforcing fibers may be continuous fibers such as carbon fibers, glass fibers, boron fibers, or aramid fibers. The matrix resin 40b may be a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, or a phenol resin, and may include a thermoplastic resin such as a nylon resin, a polyether ether ketone resin (PEEK), or a polyetherimide resin (PEI).

[0031] The opposing wall portion 15 is reinforced by including the fiber reinforced resin layer 30 in the opposing wall portion 15. In the present embodiment, the fiber reinforced resin layer 30 has substantially the same shape as the opposing wall portion 15 in a plan view and has a substantially rectangular shape extending in the vehicle width direction. However, the fiber reinforced resin layer 30 may have, for example, a substantially elliptical, substantially rectangular, or substantially polygonal shape, and may be larger than the opposing wall portion 15.

[0032] The reinforcing fibers contained in the fiber reinforced resin layer 30 may include continuous fibers oriented in the longitudinal direction of the fiber reinforced resin layer 30. The longitudinal direction refers to the long dimension direction of the fiber reinforced resin layer 30 in a plan view. For example, when the shape of the fiber reinforced resin layer 30 in a plan view is substantially rectangular, the longitudinal direction refers to the long side direction, and when the shape is substantially elliptical, the longitudinal direction refers to the long axis direction. Carbon fibers may be used as the reinforcing fibers. For example, polyacrylonitrile (PAN-based), pitch-based, cellulose-based, or other carbon fibers may be used alone or in combination.

[0033] 4 and 6 to 7, the fiber reinforced resin layer 30 extends continuously in the vehicle width direction from the vehicle left end to the vehicle right end of the wall portion 10a of the housing 10 without being divided. The fiber reinforced resin layer 30 may extend continuously in the vehicle front-rear direction from the vehicle front end to the vehicle rear end of the wall portion 10a. In other words, the fiber reinforced resin layer 30 may extend continuously from one end to the other end of the wall portion 10a of the housing 10.

[0034] The thermal expansion section 45 has the property of expanding by absorbing the heat of the gas released from the gas release section 25. The thermal expansion section 45 is disposed in the layer of the opposing wall section 15 closest to the gas release section 25 in order to receive the gas released from the gas release section 25 of the battery cell 22. In this embodiment, as illustrated in Figs. 1 to 3, the gas release section 25 is provided on the upper surface of the battery cell 22, and therefore the opposing wall section 15 is set above the battery cell 22 in the vehicle. Therefore, as shown in Figs. 4 and 6 to 7, the thermal expansion section 45 is disposed in the layer of the opposing wall section 15 closest to the vehicle lower side.

[0035] Expandable graphite, which has high thermal expansion and flame retardancy, can be used for the thermal expansion portion 45. In this manner, by including the thermal expansion portion 45 in the facing wall portion 15, heat resistance or flame retardancy is imparted to the wall portion 10a of the housing 10.

[0036] Expanded graphite is an intercalation compound in which reactive molecules such as sulfuric acid are held between layers of carbon crystals by treating, for example, powder of scaly graphite with an inorganic acid such as sulfuric acid or nitric acid, and further treating with an oxidizing agent such as concentrated nitric acid or potassium chlorate, and the crystal as a whole has a layered structure in which layers of carbon crystals are stacked. The shape of the expanded graphite is not particularly limited, and it may be in the form of powder, flakes, or particles. When the expanded graphite obtained in this way is heated, the reactive molecules between the crystal layers are gasified, and the pressure causes the expanded graphite to expand several tens to several hundreds of times in the stacking direction of the crystal layers, resulting in a fibrous form. The resin layer 40a and the matrix resin 40b described later contain such expanded graphite as the thermal expansion portion 45.

[0037] Hereinafter, the arrangement of the wall portion 10a of the housing 10, the fiber reinforced resin layer 30, and the thermal expansion portion 45 in the facing wall portion 15 will be described with reference to FIG. 4 and FIGS.

[0038] (First embodiment) 4, the wall portion 10a, the fiber reinforced resin layer 30, and the thermal expansion portion 45 included in the resin layer 40a are laminated in this order from the top of the vehicle. In other words, the fiber reinforced resin layer 30 is disposed between the wall portion 10a and the thermal expansion portion 45. In addition, the expandable graphite as the thermal expansion portion 45 is contained in the resin layer 40a laminated on the fiber reinforced resin layer 30.

[0039] The fiber reinforced resin layer 30 is formed by disposing an FRP material on the wall portion 10a. The FRP material has a shape having a thickness, such as a sheet, film, or plate.

[0040] The resin layer 40a is formed by disposing a thermally expandable resin material composed of expanded graphite and a thermoplastic resin containing the expanded graphite in the fiber reinforced resin layer 30. The thermally expandable resin material can be obtained, for example, by injecting a molten thermoplastic resin to which powdered expanded graphite has been added into a mold and cooling it. The thermally expandable resin material has a shape having a thickness, such as a sheet shape, a film shape, or a plate shape. In this embodiment, the resin layer 40a has substantially the same shape as the opposing wall portion 15 in a plan view and has a substantially rectangular shape extending in the vehicle width direction, but may have, for example, a substantially elliptical, substantially rectangular, or substantially polygonal shape, and may be larger than the opposing wall portion 15.

[0041] The illustrated opposing wall 15 may be formed by integrally molding the fiber reinforced resin layer 30 or the resin layer 40a including the thermal expansion portion 45 when the wall 10a is pressure molded. For example, a thermally expandable resin material, a prepreg that is a material of the FRP material, and SMC are laminated and arranged inside a mold used when molding the wall 10a, and pressure molded. As a result, the opposing wall 15 in which the resin layer 40a including the thermal expansion portion 45, the fiber reinforced resin layer 30, and the wall 10a are integrally molded is formed. In this way, the battery pack structure according to this embodiment can be configured by a simple manufacturing process. The opposing wall 15 may be formed by bonding an FRP material to the lower surface of the wall 10a by interposing an adhesive layer therebetween, and bonding a thermally expandable resin material to the lower surface of the FRP material.

[0042] (Modification) 6, the opposing wall 15 may be formed by stacking the fiber reinforced resin layer 30, the wall 10a, and the thermal expansion portion 45 included in the resin layer 40a in this order from the top of the vehicle. In other words, the fiber reinforced resin layer 30 may be disposed on the surface opposite the resin layer 40a including the thermal expansion portion 45 across the wall 10a. The expandable graphite as the thermal expansion portion 45 is contained in the resin layer 40a disposed in the wall 10a.

[0043] The opposing wall 15 may be formed by integrally molding the fiber reinforced resin layer 30 and the resin layer 40a including the thermal expansion portion 45 when pressure molding the wall 10a, similarly to the case of forming the opposing wall 15 illustrated in Fig. 4. This allows the battery pack structure according to the present embodiment to be configured by a simple manufacturing process. The opposing wall 15 may be formed by interposing an adhesive layer between the wall 10a and the fiber reinforced resin layer 30, or between the wall 10a and the resin layer 40a.

[0044] Second embodiment 7, the opposing wall portion 15 may include, in this order from the top of the vehicle, a wall portion 10a and a fiber reinforced resin layer 30. The thermal expansion portion 45 is made of expandable graphite contained in the matrix resin 40b of the fiber reinforced resin layer 30. In other words, the thermal expansion portion 45 is expandable graphite contained in the matrix resin 40b of the fiber reinforced resin layer 30.

[0045] The matrix resin 40b of the FRP material constituting the fiber reinforced resin layer 30 contains expandable graphite as the thermal expansion portion 45. Such an FRP material is obtained by impregnating a reinforcing fiber layer with molten matrix resin 40b to which powdered expandable graphite has been added, and then curing the prepreg obtained.

[0046] The illustrated opposing wall 15 may be formed by integrally molding the fiber reinforced resin layer 30 when the wall 10a is pressure molded. Specifically, prepreg, which is a material of FRP material having matrix resin 40b containing expanded graphite, and SMC are laminated and arranged inside a mold used for molding the wall 10a, and pressure molded. As a result, the opposing wall 15 in which the wall 10a and the fiber reinforced resin layer 30 are integrally molded is formed. This makes it possible to configure the battery pack structure according to this embodiment with a simple manufacturing process. The opposing wall 15 may be formed by bonding the FRP material having matrix resin 40b containing expanded graphite to the lower surface of the wall 10a by interposing an adhesive layer therebetween.

[0047] In the examples shown in Figs. 1 and 2, the opposing wall portion 15 has a substantially rectangular shape in plan view, but is not limited thereto. The opposing wall portion 15 may have, for example, a notch, a protruding portion, a curved portion, or an opening in plan view. In addition, in the examples shown in Figs. 4 and 6, the fiber reinforced resin layer 30 and the resin layer 40a have substantially the same cross-sectional dimensions, but are not limited thereto. For example, the cross-sectional dimensions of the fiber reinforced resin layer 30 may be larger or smaller than the cross-sectional dimensions of the resin layer 40a.

[0048] The state of the opposing wall portion 15 after the gas release portion 25 of the battery cell 22 has released gas will be described below.

[0049] 4, the opposing wall portion 15 according to the first embodiment has a battery cell 22 disposed below the vehicle. When high-temperature gas is released from the gas release portion 25 provided on the upper surface of the battery cell 22, the gas is released toward the opposing wall portion 15 located above the vehicle from the gas release portion 25. Since the opposing wall portion 15 has a resin layer 40a as the layer of the opposing wall portion 15 closest to the gas release portion 25, the gas hits the resin layer 40a.

[0050] Fig. 5 is a diagram showing the state of the opposing wall portion 15 shown in Fig. 4 after gas has been released from the gas release portion 25. In the following description, expanded graphite after thermal expansion is referred to as expanded graphite.

[0051] Since the resin layer 40a contains expanded graphite as the thermal expansion portion 45, when the high-temperature gas discharged from the gas discharge portion 25 hits the resin layer 40a, the expanded graphite contained in the resin layer 40a is heated by the heat of the gas. The heated expanded graphite expands into a fibrous shape at multiple points on the vehicle lower side surface of the resin layer 40a, forming expanded graphite 45a. As shown in FIG. 5, the expanded graphite 45a entangles with each other to form many air layers 47 between the expanded graphite 45a. The air layers 47 thus formed function as a heat insulating layer. Therefore, the heat of the high-temperature gas discharged from the gas discharge portion 25 is insulated, and the transfer of the heat of the gas to the wall portion 10a (casing 10) is suppressed. Therefore, the temperature rise of the housing 10 is suppressed.

[0052] In the opposing wall portion 15 shown in FIG. 6, a resin layer 40a containing expandable graphite as a thermal expansion portion 45 is disposed on the vehicle lower side surface of the wall portion 10a.

[0053] Even with this configuration, when the high-temperature gas discharged from the gas discharge section 25 hits the resin layer 40a, a heat insulating layer made of an air layer 47 is formed on the vehicle lower side surface of the resin layer 40a, similar to the example shown in Fig. 5. Therefore, the heat of the high-temperature gas discharged from the gas discharge section 25 is insulated, and the transfer of the heat of the gas to the wall section 10a (housing 10) is suppressed. Therefore, the temperature rise of the housing 10 is suppressed.

[0054] In addition, the opposing wall portion 15 according to the second embodiment shown in FIG. 7 has a fiber-reinforced resin layer 30 including a matrix resin 40b containing expandable graphite as a thermal expansion portion 45 disposed on the vehicle lower side surface of the wall portion 10a.

[0055] In this configuration, when the high-temperature gas discharged from the gas discharge section 25 hits the fiber-reinforced resin layer 30, the expanded graphite contained in the matrix resin 40b is heated by the heat of the gas. The heated expanded graphite expands into a fibrous form, forming expanded graphite 45a at multiple locations on the vehicle lower side surface of the fiber-reinforced resin layer 30. The expanded graphite 45a entangles with each other in the same manner as in the example shown in FIG. 5, forming many air layers 47 between the expanded graphite 45a. The air layers 47 thus formed function as a heat insulating layer. Therefore, the heat of the high-temperature gas discharged from the gas discharge section 25 is insulated, and the transfer of the heat of the gas to the wall section 10a (housing 10) is suppressed.

[0056] 4 and 6 to 7 is reinforced by a fiber-reinforced resin layer 30. More specifically, an area of ​​the housing 10 where the temperature may increase and the strength may decrease due to the impact of the released gas is reinforced by the fiber-reinforced resin layer 30 containing reinforcing fibers. Therefore, even if the pressure inside the housing 10 increases due to the release of the gas, deformation of the wall 10a (housing 10) is suppressed.

[0057] The effects of this embodiment will be described below.

[0058] (1) A battery pack structure according to an embodiment includes one or more battery cells 22, each having a gas release portion 25 that releases gas, and a housing 10 that houses the one or more battery cells 22. An opposing wall portion 15 of the housing 10 that faces at least the gas release portion 25 includes at least a part of a wall portion 10a that surrounds the one or more battery cells 22 of the housing 10, a fiber reinforced resin layer 30 that reinforces the opposing wall portion 15, and a thermal expansion portion 45 that is disposed in a layer of the opposing wall portion 15 closest to the gas release portion 25 and expands by absorbing heat of the gas released from the gas release portion 25.

[0059] As a result, when the battery cell 22 releases high-temperature gas, the thermal expansion section 45 absorbs the heat of the gas and expands, forming an insulating layer inside the housing 10. Therefore, the heat of the gas is insulated by the insulating layer, and the transfer of the heat of the gas to the housing 10 is suppressed. This makes it possible to suppress an increase in the temperature of the housing caused by the transfer of the heat of the gas to the housing. Furthermore, an area of ​​the housing 10 that may be affected by the released gas and thus experience an increase in temperature and a decrease in strength is reinforced by the fiber-reinforced resin layer 30 containing reinforcing fibers. Therefore, when the pressure inside the housing 10 increases due to the release of the gas and pressure is input from the inside to the housing 10, the fiber-reinforced resin layer 30 suppresses deformation of the housing.

[0060] (2) In the battery pack structure of the first embodiment, the fiber reinforced resin layer 30 is disposed between the wall portion 10a and the thermal expansion portion 45, and the thermal expansion portion 45 is expanded graphite contained in the resin layer 40a laminated on the fiber reinforced resin layer 30.

[0061] Since the thermal expansion portion 45 is made of expanded graphite, when the high-temperature gas emitted by the battery cell 22 hits the resin layer 40a, the expanded graphite absorbs the heat of the gas and thermally expands several tens to several hundreds of times to become fibrous. Then, the thermally expanded expanded graphite (expanded graphite 45a) becomes entangled with each other to form an air layer 47 (thermal insulation layer). Therefore, the heat of the gas is more reliably insulated, and the transfer of the heat of the gas to the housing 10 is suppressed.

[0062] (3) In a battery pack structure relating to a modified example of the first embodiment, the fiber reinforced resin layer 30 is disposed on the side opposite the thermal expansion portion 45 across the wall portion 10a, and the thermal expansion portion 45 is expanded graphite contained in the resin layer 40a disposed on the wall portion 10a.

[0063] Since the thermal expansion portion 45 is made of expanded graphite, when the high-temperature gas emitted by the battery cell 22 hits the resin layer 40a, the expanded graphite absorbs the heat of the gas and thermally expands several tens to several hundreds of times to become fibrous expanded graphite 45a. The expanded graphite 45a then entangles with each other to form an air layer 47 (thermal insulation layer). This more reliably insulates the heat of the gas, and suppresses the transfer of the heat of the gas to the housing 10.

[0064] (4) In the battery pack structure according to the second embodiment, the thermal expansion portion 45 is expanded graphite contained in the matrix resin 40 b of the fiber reinforced resin layer 30 .

[0065] Since the thermal expansion portion 45 is made of expanded graphite, when the high-temperature gas emitted by the battery cell 22 hits the fiber reinforced resin layer 30, the expanded graphite contained in the matrix resin 40b absorbs the heat of the gas and thermally expands several tens to several hundreds of times to become fibrous expanded graphite 45a. The expanded graphite 45a then entangles with each other to form an air layer 47 (thermal insulation layer). Therefore, the heat of the gas is more reliably insulated and the transfer of the heat of the gas to the housing 10 is suppressed. Furthermore, since the expanded graphite is contained in the matrix resin 40b of the fiber reinforced resin layer 30, the thermal expansion portion 45 and the fiber reinforced resin layer 30 can be handled as a single unit. Therefore, the thermal expansion portion 45 and the fiber reinforced resin layer 30 can be easily disposed on the wall portion 10a of the housing 10. This makes it possible to easily configure the battery pack structure according to the embodiment.

[0066] (5) In the battery pack structure according to the embodiment, the reinforcing fibers contained in the fiber reinforced resin layer 30 include continuous fibers oriented in the longitudinal direction of the fiber reinforced resin layer 30 .

[0067] This provides the fiber reinforced resin layer 30 with higher tensile strength in the longitudinal direction, and therefore the fiber reinforced resin layer 30 can more reliably suppress deformation of the housing 10 caused by an increase in pressure inside the housing 10.

[0068] (6) In the battery pack structure according to the embodiment, the reinforcing fibers contained in the fiber reinforced resin layer 30 are made of carbon fibers.

[0069] The fiber reinforced resin layer 30 is a carbon fiber reinforced resin (CFRP) containing reinforcing fibers made of carbon fibers. Therefore, the fiber reinforced resin layer 30 has a higher tensile strength. As a result, the fiber reinforced resin layer 30 can more reliably suppress deformation of the housing caused by an increase in pressure inside the housing.

[0070] (7) In the battery pack structure according to the embodiment, the fiber reinforced resin layer 30 extends continuously from one end to the other end of the wall portion 10a of the housing 10.

[0071] This allows the fiber reinforced resin layer 30 to more reliably reinforce the housing 10 between one end and the other end of the wall portion 10a of the housing 10. Therefore, the fiber reinforced resin layer 30 can more reliably suppress deformation of the housing 10 caused by an increase in pressure inside the housing 10.

[0072] In the above embodiment, an electric vehicle (EV) has been described as an example, but the battery pack 1 can of course also be applied to a hybrid vehicle (HV) or the like. [Explanation of symbols]

[0073] 1 Battery pack 10. Chassis 10a wall 15 Opposing wall 20 Battery Module 22 Battery Cell 25 Gas release section 30 Fiber reinforced resin layer 40a Resin layer 40b matrix resin 45 Thermal expansion section

Claims

1. One or more battery cells each having a gas release portion that releases gas; a housing that houses the one or more battery cells; Equipped with At least a facing wall portion of the housing facing the gas release portion is At least a portion of a wall portion of the housing that surrounds the one or more battery cells; A fiber reinforced resin layer that reinforces the opposing wall portion; a thermal expansion section that is disposed in a layer of the opposing wall section closest to the gas discharge section and expands by absorbing heat of the gas discharged from the gas discharge section, The fiber reinforced resin layer is disposed between the wall portion and the thermal expansion portion.

2. One or more battery cells each having a gas release portion that releases gas; a housing that houses the one or more battery cells; Equipped with At least a facing wall portion of the housing facing the gas release portion is At least a portion of a wall portion of the housing that surrounds the one or more battery cells; A fiber reinforced resin layer that reinforces the opposing wall portion; a thermal expansion section that is disposed in a layer of the opposing wall section closest to the gas discharge section and expands by absorbing heat of the gas discharged from the gas discharge section, The fiber-reinforced resin layer is disposed on a surface of the wall opposite the thermal expansion portion.

3. The battery pack structure described in claim 1, characterized in that the thermal expansion portion is expanded graphite contained in a resin layer laminated to the fiber reinforced resin layer.

4. A battery pack structure as described in claim 2, characterized in that the thermal expansion portion is expanded graphite contained in a resin layer arranged in the wall portion.

5. 5 . The battery pack structure according to claim 1 , wherein the reinforcing fibers contained in the fiber-reinforced resin layer include continuous fibers oriented in a longitudinal direction of the fiber-reinforced resin layer. 6 .

6. 6. The battery pack structure according to claim 1, wherein the reinforcing fibers contained in the fiber-reinforced resin layer are made of carbon fibers.

7. 7. The battery pack structure according to claim 1, wherein the fiber-reinforced resin layer extends continuously from one end to the other end of the wall of the housing.

Images