Case structure and battery case

Abstract

A case structure which is for a part to be installed outside an occupant space of a moving body and in which a metal layer and a resin layer are arranged at least in the thickness direction, wherein the metal layer is arranged in the outermost layer, the resin layer has a reinforcing shape extending in at least two directions, the two directions intersect each other in a plan view in a third angle system, the metal layer and the resin layer are joined to each other at a joint portion, and an air layer is present between the metal layer and the resin layer in a region excluding the joint portion. It is possible to provide a case structure in which fire resistance performance is enhanced by a flame shielding effect exerted by the outermost metal layer and a heat insulating effect exerted by the air layer, and the rigidity is enhanced by the reinforcing shape of the resin layer in at least two directions, and it is also possible to provide a battery case for housing a drive battery for an electric automobile that uses this case structure.

Description

[Technical Field]

[0001] The present invention relates to a case structure, particularly a case structure suitable for a case for an electric vehicle, and a battery case using the same. [Background technology]

[0002] Some developed countries are moving to ban the sale of pure gasoline-powered vehicles between 2030 and 2040, and car manufacturers are accelerating their development efforts to respond to this. In particular, for electric vehicles (EVs), extending their driving range is an immediate challenge, and there is growing emphasis on technologies that make full use of materials such as resins and CFRP (carbon fiber reinforced plastics), which can reduce the weight of the vehicle body.

[0003] Among these, the battery case that houses the drive battery of an EV is a large component that occupies almost the entire area under the vehicle floor, and replacing steel with this material offers significant weight reduction benefits. For example, Patent Document 1 proposes a box-shaped battery case with an upper cover and lower case made of CFRP, which combines light weight with excellent mechanical properties. However, the battery case has not passed the fire resistance test stipulated in the 2013 United Nations Convention on EVs (UN-ECE R100.02), which requires the battery case to be exposed to a gasoline flame at approximately 900°C for several minutes.

[0004] One method of imparting fire resistance to CFRP materials is to add flame retardants such as halogen-based ones (Patent Document 2). This is sufficient at the melting temperature of the matrix resin, but in fire resistance tests, not only did the case itself melt, but the heated battery could potentially cause thermal runaway. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-94476 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-131394 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a case structure that is lightweight while having fire resistance, and a battery case using the same. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention has the following features. (1) A case structure for a part to be installed outside the passenger space of a moving body, in which a metal layer and a resin layer are arranged at least in the thickness direction, the metal layer being arranged as the outermost layer, the resin layer having a reinforcing shape extending in at least two directions, the two directions intersecting each other in a plan view in third angle projection, the metal layer and the resin layer being joined to each other at a joint, and an air layer being present between the metal layer and the resin layer in an area excluding the joint. (2) A case structure as described in (1), wherein the reinforcing shape extends in a third direction in the plan view in third angle projection in addition to the two directions. (3) The case structure according to (1) or (2), wherein the reinforcing shape is an uneven shape. (4) A case structure as described in (3), in which a fiber-reinforced thermoplastic resin tape sheet consisting of continuous reinforcing fibers and a thermoplastic resin is arranged on the surface of the uneven shape opposite the metal layer. (5) The case structure according to (3) or (4), wherein the uneven shape is a rib shape. (6) A case structure according to (3) or (4), wherein the concave and convex shape is a hat shape. (7) The case structure according to (5), wherein the rib shape forms a continuous polygon. (8) A case structure according to any one of (1) to (7), wherein the air layer is inclined relative to a horizontal plane. (9) A case structure according to any one of (1) to (8), wherein the thickness of the air layer is 1 mm or more and 3 mm or less. (10) A case structure according to any one of (1) to (9), in which a flame-resistant yarn mat is installed in the air layer. (11) A case structure according to any one of (1) to (10), wherein the resin layer contains at least one thermoplastic resin selected from polypropylene, polyamide, polycarbonate, polybutylene terephthalate, ABS, and polyphenylene sulfide. (12) A case structure according to any one of (1) to (11), wherein the resin layer contains a thermoplastic resin having a melting temperature of 250°C or higher and 400°C or lower. (13) The case structure according to any one of (1) to (12), wherein the resin layer contains at least one type of reinforcing fiber selected from carbon fiber, glass fiber, and organic fiber. (14) A case structure according to any one of (1) to (13), wherein the joining method for the joint portion is at least one joining method selected from rivet joining, screw joining, resin crimping joining, adhesive joining, and welding. (15) A battery case for storing a drive battery of an electric vehicle, the battery case having a box-like shape including at least an upper cover and a lower tray, a battery module fixed to the upper surface side of the lower tray, and the upper cover and / or the lower tray including the case structure described in any one of (1) to (14). [Effects of the Invention]

[0008] The present invention provides a case structure that has improved fire resistance due to the flame-blocking effect of the outermost metal layer and the insulating effect of the air layer, and has increased rigidity due to the reinforcement shape of the resin layer in at least two directions, and a battery case that uses this case structure to store an EV drive battery. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a partial cross-sectional view of a case structure showing an example of a reinforcing shape in the present invention. [Figure 2]FIG. 10 is a partial cross-sectional view of a case structure showing another example of a reinforcing shape in the present invention. [Figure 3] FIG. 1 is a partial cross-sectional view showing an example of a case structure of the present invention. [Figure 4] FIG. 4 is a partial cross-sectional view showing another example of the case structure of the present invention. [Figure 5] 10A and 10B are a partial front cross-sectional view and a partial side cross-sectional view, respectively, showing still another example of the case structure of the present invention. [Figure 6] 1A is a top perspective view, FIG. 1B is a bottom perspective view, and FIG. 1C is an enlarged partial side view showing an example of a battery case of the present invention. [Figure 7] 1A is a top perspective view, FIG. 1B is a bottom perspective view, and FIG. 1C is an enlarged partial side view showing another example of a battery case of the present invention. [Figure 8] 1A and 1B are a top perspective view and a bottom perspective view, respectively, showing an example of a steel battery case according to a comparative example. [Figure 9] 1A is a partial top perspective view showing an example of a case structure of the present invention, FIG. 1B is a partial front end view, and FIG. 1C is a partial right end view. [Figure 10] 1A is a partial top perspective view, FIG. 1B is a partial front end view, and FIG. 1C is a partial right end view showing a laminated structure of a resin flat plate and a metal plate, which is cited as a comparative example. [Figure 11] 1A is a partial top perspective view, FIG. 1B is a partial front end view, and FIG. 1C is a partial right side end view showing a laminated structure of a resin plate and a metal plate having a unidirectional rib shape, which is cited as a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of a case structure according to the present invention and a battery case using the same will be described in detail.

[0011] The case structure of the present invention is a case structure for parts to be installed outside the passenger space of a moving body, which has a metal layer and a resin layer arranged at least in the thickness direction, and is characterized in that the metal layer is arranged as the outermost layer, the resin layer has a reinforcing shape extending in at least two directions, the two directions intersecting each other in a plan view in third angle projection, the metal layer and the resin layer are joined to each other at a joint, and there is an air layer between the metal layer and the resin layer in an area excluding the joint.

[0012] According to the findings of the inventors, a case structure that satisfies all of these characteristics has excellent fire resistance due to the flame-blocking effect of the outermost metal layer and the insulating effect of the air layer, and is lightweight and rigid due to the reinforcement shape of the resin layer in at least two directions, making it suitable for use as a case for transportation machinery parts, particularly a battery case.

[0013] Next, the components of the case structure according to the present invention will be described in the order of the resin layer, the metal layer, the joining method, and the air layer.

[0014] The resin layer is the main part of the case structure, and the important factors for it are the volume for accommodating components, rigidity, and light weight.

[0015] The reinforcing shape of the resin layer is a shape formed during the resin molding process or when combined with other reinforcing materials, and includes a shape for reinforcing with the resin itself and a shape for combining with other reinforcing materials.Specific examples include a method of forming a reinforcing shape when molding the resin layer by injection molding or press molding, a method of forming a reinforcing shape by heating and deforming a pre-molded resin layer when welding other reinforcing materials to it, a method of forming a reinforcing shape with an adhesive when bonding other reinforcing materials, and a method of forming a reinforcing shape by cutting.

[0016] A preferred reinforcing shape is an uneven shape having concaves and convexes, which increases the moment of inertia of area and provides efficient reinforcement.

[0017] Specific examples of the concave-convex shape for reinforcing the resin itself include a hat shape, a cylindrical shape, a hollow cone shape, a polygonal tube shape, and a rib shape. Examples of the concave-convex shape for combining with other reinforcing materials include a groove shape and a padding shape. The groove shape and the padding shape will be explained using FIGS. 1 and 2.

[0018] Figure 1 shows a resin layer 1 having grooves as reinforcing shapes. The grooves 2 are shapes that allow reinforcing material 3 to be embedded in the upper surface of the resin layer 1, and can improve adhesion between the resin layer and the reinforcing material.

[0019] 2 shows a resin layer 4 having a buildup shape as a reinforcing shape. The buildup shape 5 is a shape that covers the end of the reinforcing material 3 on the upper surface of the resin layer, and can improve the adhesion between the resin layer and the reinforcing material.

[0020] More preferred reinforcing shapes include a rib shape and a hat shape. The rib shape is preferred because it has a high reinforcing effect, and the hat shape is preferred because it is a reinforcing shape that is less likely to cause molding defects such as shrinkage and voids and has excellent moldability.

[0021] The extension direction of the reinforcing shape of the present invention is at least two directions, and there are no particular restrictions on the two directions as long as they intersect with each other in a plan view in third angle projection, such as two directions that intersect with each other on a certain plane or two directions that intersect with each other when viewed three-dimensionally.

[0022] Furthermore, the two extending directions of the reinforcing shape according to the present invention are not particularly limited in the position of the intersection as long as they intersect in a plan view in third angle projection, and they may intersect in an area outside the case structure in the plan view. Intersecting in an area inside the case structure in the plan view is preferable because it increases rigidity.

[0023] If the reinforcing shape extends in only one direction, the anisotropy of the mechanical properties of the case structure increases, so it is important that the reinforcing shape extend in at least two directions.

[0024] Furthermore, a more preferable example of the extending direction of the reinforcing shape is extending in a third direction in the plan view in the third angle projection in addition to the two directions. By making the extending direction of the reinforcing shape the three directions, the reinforcing effect of the case structure can be enhanced more isotropically, which is preferable. Examples of combinations of the three directions include a certain direction, a direction at 45 degrees from the certain direction, and a direction at 90 degrees from the certain direction in the plan view, but the combinations are not limited to these and various combinations can be used.

[0025] It is preferable that the upper surfaces of the reinforcing shapes extending in two directions according to the present invention, on the side opposite the metal layer, are in the same plane, since the devices to be housed in the case can be housed efficiently if the upper surfaces of the reinforcing shapes are in the same plane.

[0026] In the rib shape according to the present invention, it is preferable that the ribs extending in at least the two directions are integrated into a continuous polygonal shape. A polygonal rib shape is preferable because it not only provides efficient reinforcement but also allows battery modules or battery cells to be stored in cavities surrounded by the rib shape. Examples of suitable polygonal shapes include a triangular shape, a square shape, and a hexagonal shape. A square grid is preferable because it can efficiently store box-shaped battery modules, and a triangular isogrid or a hexagonal honeycomb is preferable because it can efficiently store cylindrical battery cells.

[0027] The resin layer according to the present invention may be combined with other reinforcing materials. The other reinforcing material is not particularly limited, but examples thereof include metal members, fiber-reinforced resin tape sheets, etc. A fiber-reinforced thermoplastic resin tape sheet in which continuous reinforcing fibers are impregnated with a thermoplastic resin is preferably used because it is easy to combine with the resin layer.

[0028] The method for combining the resin layer and the fiber-reinforced thermoplastic resin tape sheet according to the present invention is not particularly limited, but examples include a method in which the tape sheet is inserted into a mold before molding the resin layer and embedded on the surface or inside of the resin layer, or a method in which the tape sheet is attached to the molded resin layer afterwards. In addition, the fiber-reinforced thermoplastic resin tape sheet can be combined with the resin layer in a state in which it has been previously shaped into a curved or bent shape.

[0029] The fiber-reinforced thermoplastic resin tape-like sheet is preferred because it can efficiently reinforce the case structure by being adjacent to the reinforcing shape of the resin layer in the present invention. More preferably, the fiber-reinforced thermoplastic resin tape-like sheet is adjacent to the uneven shape in the present invention, and even more preferred installation locations for the fiber-reinforced thermoplastic resin tape-like sheet include a ribbed upright wall surface and a hat-shaped top surface.

[0030] The form of the continuous reinforcing fibers contained in the fiber-reinforced thermoplastic resin tape-like sheet is not particularly limited, and examples include a form in which the fibers are aligned in one direction, a form in which fibers are aligned in one direction and laminated, a woven form, etc. A more preferred form is a thermoplastic UD tape in which the reinforcing fibers are aligned in one direction, because this can efficiently utilize the mechanical properties of the reinforcing fibers to reinforce the case structure.

[0031] The reinforcing fibers contained in the fiber-reinforced thermoplastic resin tape-like sheet are not particularly limited, and at least one of organic fibers, glass fibers, and carbon fibers can be used.

[0032] The thermoplastic resin contained in the fiber-reinforced thermoplastic resin tape sheet is not particularly limited, and any resin suited to the required properties can be used.

[0033] The resin contained in the resin layer in the present invention is preferably at least one thermoplastic resin selected from polypropylene, polyamide, polycarbonate, polybutylene terephthalate (PBT), ABS, and polyphenylene sulfide, because it allows for flexible molding of a reinforcing shape with a high reinforcing effect. More preferred resins contained in the resin layer in the present invention include thermoplastic resins with a melting temperature of 250°C or higher and 400°C or lower. A melting temperature of 250°C or higher is preferred because it increases the fire resistance of the case structure. A melting temperature of 400°C or lower is preferred because it allows for flexible molding of a reinforcing shape with a high reinforcing effect.

[0034] The reinforcing fibers contained in the resin layer in the present invention are not particularly limited, but include at least one type of reinforcing fiber selected from carbon fiber, glass fiber, and organic fiber. Carbon fiber is preferred because it dramatically increases the strength and rigidity of the resin layer. Glass fiber, although not as strong as carbon fiber, is preferred because it increases strength and rigidity and is low cost. Organic fiber is preferred because it increases impact resistance.

[0035] In the present invention, the resin layer is preferably formed in a shape surrounded by a wall on the periphery, because this shape provides high rigidity and excellent capacity for accommodating contents. In addition, since the rigidity is further increased by increasing the height of the wall, the height of the wall can be selected from the viewpoints of the volumetric limit of the case structure and the required rigidity.

[0036] The form of the material used for the resin layer in the present invention is not particularly limited, and it can be in various forms such as pellets, plates, blocks, or melt-kneaded mixtures.

[0037] Next, the metal layer in the present invention will be described. It is important that the metal layer in the present invention can block external flames. Therefore, at least one of steel, aluminum (including aluminum alloys), and flame-retardant magnesium alloys is preferably used as the metal material constituting the metal layer. Steel is preferred from the viewpoint of low cost procurement, and aluminum is preferred from the viewpoint of light weight.

[0038] The metal layer in the present invention is preferably subjected to a surface treatment capable of reflecting radiant heat. Preferred surface treatments include surface polishing, plating, thermal spraying, and coating. A more preferred surface treatment is zinc plating, which is relatively inexpensive.

[0039] The metal layer in the present invention is preferably thinner because it is lighter in weight. Specifically, the preferred thickness is 2 mm or less, and more preferably 1 mm or less.

[0040] The shape of the metal layer in the present invention is not particularly limited, and various shapes can be selected as long as the effects of the present invention are not impaired. For example, a flat plate shape is preferable because it reduces the number of processing steps, and a bead shape or a corrugated plate shape is preferable because it can suppress deflection due to its own weight. In addition, various shapes can be selected, such as a box shape that surrounds the entire periphery of the resin layer, a plate shape that covers only the lower surface of the resin layer, or a tray shape that covers the lower surface and side surfaces of the resin layer.

[0041] The method for joining the resin layer and the metal layer in the present invention is not particularly limited, and various joining methods can be selected. Preferred joining methods include rivet joining, screw joining, resin caulking joining, adhesion, and welding, which are widely used in machine parts, etc.

[0042] An example of a preferred joining method will be described with reference to Fig. 3. In the case structure 6 shown in Fig. 3, a ribbed resin layer 7 and a hat-shaped metal layer 8 are bonded together on the side opposite the metal layer with adhesive 9 disposed at a joint S. An air space 10 exists between the resin layer 7 and the metal layer 8, excluding the joint S. Joining by adhesive is preferred because it allows for a wide joining surface.

[0043] Another preferred example of the joining method will be described with reference to Fig. 4. The case structure 11 shown in Fig. 4 is formed by joining a resin layer 12 having a rib shape on the side opposite the metal layer to a hat-shaped metal layer 13 at a crimped portion 14 formed by crushing a resin boss passed through a hole in the metal layer 13. This method is preferred because the strength of the crimped portion can be estimated from the strength of the resin, making it easy to handle in design.

[0044] The air layer in the present invention refers to the layer between the metal layer and the resin layer in the area excluding the joint where the metal layer and the resin layer are joined, and it is important that it can insulate against heat from the outside.

[0045] The thickness of the air layer in the present invention is not particularly limited, and various thicknesses can be selected within a range that does not impair the effects of the present invention. For example, by increasing the thickness of the air layer, the heat insulating properties of the air layer can be improved, while by decreasing the thickness of the air layer, the heat insulating properties will decrease but the entire case structure can be made thinner.

[0046] The specific thickness of the air layer in the present invention is preferably 1 mm or more and 3 mm or less. A thickness of 1 mm or more is preferable because the heat insulating effect of the air layer is particularly excellent. Furthermore, a thickness of 3 mm or less is preferable because the entire case structure can be made thinner.

[0047] In the present invention, the air layer is preferably inclined with respect to the horizontal plane, since this allows the heated air to be efficiently released to the outside of the case structure.

[0048] The inclination of the air layer with respect to the horizontal plane will be explained using an example of a case structure in Fig. 5. This case structure 15 has a resin layer 16 with a rib shape on the side opposite the metal and a hat-shaped metal layer 17 joined at a joint S with adhesive 18. In the AA cross-sectional view (b) of this case structure 15, the upper surface 20 and the lower surface 21 of the air layer 19 are inclined with respect to a horizontal plane 22. In Fig. 5, the air layer 19 is inclined in the extension direction of the hat shape of the metal layer 17, but this is not limited thereto, and it is preferable that the air layer 19 be inclined in the width direction and / or length direction of the case structure.

[0049] The air layer in the present invention may contain a nonwoven fabric material or a porous material as a core material for the purpose of suppressing air convection. When the case structure of the present invention is heated by a flame from the outside, the air layer preferably contains the core material, which can suppress convection of air warmed on the metal layer side, which is the outermost layer, toward the resin layer side, thereby further enhancing the heat insulating properties of the air layer.

[0050] Preferred core materials include glass fiber mats, carbon fiber mats, organic fiber mats, flame-resistant yarn mats, foam materials, porous ceramics, porous carbon materials, and honeycomb cores. From the viewpoint of cost, glass fiber mats are preferred, and flame-resistant yarn mats are preferred from the viewpoints of heat insulation, light weight, and heat resistance.

[0051] The case structure of the present invention may include a reinforcing frame in the width direction and / or length direction of the case structure, as long as the effect of the present invention is not impaired. By including a reinforcing frame, the rigidity and strength of the case structure can be increased, which is preferable.

[0052] Next, a method for manufacturing the case structure of the present invention will be described. The method for manufacturing the case structure of the present invention preferably includes at least the following steps (i), (ii), and (iii). (i) Step of molding a resin layer (ii) forming a metal layer (iii) A process of joining the separately molded resin layer and metal layer

[0053] The molding method for molding the resin layer is not particularly limited, and examples thereof include injection molding, press molding, and injection press molding. From the exemplified molding methods, a manufacturing method suited to the molding characteristics of the material to be used can be selected.

[0054] The method for forming the metal layer is not particularly limited, but examples include sheet metal press molding and slip casting. Alternatively, a metal plate may be cut to a desired size and then combined with a resin layer without undergoing a molding process.

[0055] The method for joining the resin layer and the metal layer, which are separately molded, is not particularly limited, and various joining methods can be selected. Joining the resin layer and the metal layer, which are separately molded, is preferred because it ensures the formation of an air layer between the resin layer and the metal layer.

[0056] The case structure of the present invention is intended for components to be installed outside the passenger space of a moving body, and examples of such moving bodies include electrically driven automobiles such as EVs, HEVs (hybrid electric vehicles), and PHEVs (plug-in hybrid electric vehicles), electrically assisted bicycles, electric motorcycles, construction machinery, flying objects such as drones, air mobility, and helicopters, aircraft, and industrial assembly / transportation robots.

[0057] Furthermore, examples of components to which the case structure of the present invention can be applied include battery cases, inverter cases, motor cases, and other control system component cases.

[0058] Next, the battery case for accommodating the driving battery of the EV of the present invention will be described. The battery case of the present invention has a box-like shape including at least an upper cover and a lower tray, a battery module is fixed to the upper surface side of the lower case, and the case structure of the present invention is used for either or both of the upper cover and the lower tray.

[0059] In the battery case of the present invention, the method for assembling the upper cover and lower tray is not particularly limited, and various methods can be used. For example, they can be fastened with screws via a flange, hooked with fixing tabs, adhered with an adhesive, or welded. Furthermore, if the battery case is required to be watertight / airtight, rubber seals, Teflon (registered trademark) seals, metal seals, etc. can be used in the assembly parts.

[0060] Figure 6 shows the upper surface (a), lower surface (b), and enlarged partial side view (c) of a lower tray 23 in an EV drive battery case using the case structure of the present invention. The lower tray 23 is composed of a box-shaped resin layer 24, a continuous hat-shaped metal layer 25, a metal layer 26 that also serves as a reinforcing frame, and a thermoplastic UD tape 27. The resin layer 24 has a hat shape 28 extending in three directions on the inner bottom of the box shape, and the thermoplastic UD tape 27 is disposed on the top surface of the hat shape. The reinforcement of the hat shape 28 extending in three directions and the thermoplastic UD tape 27 increases the rigidity of the case structure. The inner bottom of the resin layer 24 also has boss shapes 29 for screwing the battery module and rib shapes 30 that support the boss shapes. The outer bottom surface of the lower tray 23 is covered with the continuous hat-shaped metal layer 25 and the metal layer 26 that also serves as a reinforcing frame, providing flame resistance. The resin layer and the metal layer are joined with an adhesive, and an air layer 32 that functions as a heat insulating layer is provided between the resin layer and the metal layer in the area excluding the joint 31. The lower tray 23 is assembled to the vehicle body structure via an assembly portion 33 of the reinforcing frame, and is assembled to the upper cover via a flange portion 34.

[0061] Next, Figure 7 shows the upper side (a), lower side (b), and enlarged partial side (c) of a lower tray 35 in an EV drive battery case using a different configuration of the case structure of the present invention from that shown in Figure 6. The lower tray 35 is composed of a box-shaped resin layer 36, a continuous hat-shaped metal layer 37, and a metal layer 38 that also serves as a reinforcing frame. The resin layer 36 has an isogrid-like rib shape 39 on the inner bottom of the box-shaped lower tray 35, which increases the rigidity of the case structure. As in Figure 6, the outer bottom surface of the lower tray 35 is covered with the continuous hat-shaped metal layer 37 and the metal layer 38 that also serves as a reinforcing frame, providing flame resistance. Also, as in Figure 6, an air layer 41 is provided between the resin layer and the metal layer in an area other than the joint 40 between the resin layer and the metal layer, and this air layer 41 functions as a thermal insulating layer.

[0062] 9 shows a partial top perspective view (a) showing a part of the element shape of the case structure of the present invention (partial case structure 47), a partial front end view (b) showing only the end face of the partial case structure 47 when viewed from the front, and a partial right end view (c) showing only the end face of the case structure 47 when viewed from the right side. The partial case structure 47 is composed of a resin plate 48 having a cross-shaped rib shape 49, an air layer 50, and a metal plate 51.

[0063] The partial case structure 47 is characterized by high rigidity in two directions, the front-to-rear direction and the left-to-right direction, due to the cross rib shape 49. The specific rigidity in the two directions is calculated using the rigidity value of the partial front end view (b) and the rigidity value of the partial right side end view (c) using the following formula (1). Stiffness=E r ×I r +E m ×I m (1) E r : Elastic modulus of resin layer I r : Moment of inertia of the resin layer E m : Elastic modulus of the metal layer I m : Moment of inertia of the metal layer

[0064] 9, a test specimen is prepared and heated by combustion from the metal layer 51 side using a gas burner. The evaluation index is not particularly limited, but examples include the temperature of the anti-flame side after a certain time has elapsed since the start of heating, and the state of resin melting on the flame side and anti-flame side of the test specimen.

[0065] 10 shows a laminated structure 52 of a resin flat plate and a metal plate, which is different from the case structure of the present invention. The laminated structure 52 is composed of three layers: a resin flat plate 53, an air layer 54, and a metal plate 55, and has excellent fire resistance. However, because the resin flat plate 53 does not have a reinforcing structure, the rigidity values ​​calculated for the partial front end view (b) and the partial right side end view (c) are inferior to the case structure of FIG.

[0066] 11 shows a laminated structure 56 of a resin plate and a metal plate having a unidirectional rib shape, which differs from the case structure of the present invention. The laminated structure 56 is composed of three layers: a resin plate 57 having a unidirectional rib shape, an air layer 59, and a metal plate 60. It has excellent fire resistance and a high rigidity value in the partial front end view (b) where the unidirectional rib shape 58 is reinforced. However, because the resin plate 57 does not have a reinforcing shape, the calculated rigidity value in the partial right side end view (c) is inferior to that of the case structure of FIG. 9. [Example]

[0067] The present invention will be described below based on examples, but first, the evaluation methods used in the present invention and the materials used in each example and comparative example will be described.

[0068] <Evaluation method> (natural frequency) An electronic drawing of the battery case lower tray was created on a computer, and the materials used for each part of the lower tray were defined. The primary natural frequency, which increases with the rigidity of the lower tray, was then calculated through simulation analysis using CAE (Computer Aided Engineering).

[0069] (rigidity) The rigidity was calculated for each of the two directions of the partial front end view (b) and the partial right side end view (c) of the test specimens (Figs. 9-11) obtained in Examples 3 to 7 and Comparative Examples 2 to 4 using the following formula (1) (same as the formula 1 above). Stiffness=E r ×I r +E m ×I m (1) E r : Elastic modulus of resin layer I r : Moment of inertia of the resin layer E m : Elastic modulus of the metal layer I m : Moment of inertia of the metal layer

[0070] (Fire resistance) The test specimen was placed horizontally in an 80mm x 80mm metal frame, and the underside of the specimen was heated by a gas burner. The temperature near the heated surface by the gas burner was 800-950°C, and the heating time was 130 seconds. No load was applied to the specimen, and the atmosphere during evaluation was room temperature and atmospheric pressure. The temperature was measured 130 seconds after heating began using a thermocouple fixed to the center of the top surface of the sample. After the test, the presence or absence of resin melting on the flame side and anti-flame side of the sample was also confirmed.

[0071] <Material> The materials and components used in each example and comparative example are as follows: [Carbon fiber (A)] A-1: Toray Industries, Inc. "Torayca (registered trademark)" thread T700S-12K

[0072] [PPS (polyphenylene sulfide) resin (B)] B-1: Toray Industries, Inc., "Torelina (registered trademark)" A900

[0073] [Thermoplastic UD Tape (C)] C-1: Thermoplastic UD tape Carbon fiber (A-1) (Toray Industries, Inc., Torayca® yarn T700S-12K) was prepared and continuously fed through a yarn guide. The continuously fed carbon fiber was impregnated with PPS resin (B-1) by a fixed amount supplied from a filled feeder in an impregnation die. The carbon fiber impregnated with PPS resin (B-1) was then continuously drawn through the nozzle of the impregnation die using a take-up roll. The PPS resin (B-1) was cooled and solidified by passing through a cooling roll, and the resulting thermoplastic UD tape was wound on a winder. The resulting thermoplastic UD tape had a thickness of 0.3 mm and the carbon fibers were aligned in one direction. The carbon fiber content in the thermoplastic UD tape was 50 vol%.

[0074] [Glass fiber reinforced PPS resin pellets (D)] D-1: Toray Industries, Inc., "Torelina (registered trademark)" A503-X05 Flexural modulus 11.3GPa

[0075] Steel ·E-1:SPCC steel plate Elastic modulus 192GPa

[0076] [Flame-resistant yarn mat (F)] F-1: Zoltek OXFT FT0500-200

[0077] (Reference example 1) The PPS resin (B-1) was subjected to injection molding using an injection molding machine (J110AD manufactured by The Japan Steel Works, Ltd.) under the following conditions: injection time: 2 seconds, back pressure: 5 MPa, dwell pressure: 20 MPa, dwell time: 10 seconds, cylinder temperature: 300°C, and mold temperature: 120°C, to produce a resin plate having a cross-rib shape as shown in 48 in Figure 9. The dimensions were w1 = 80 mm, d1 = 80 mm, tp1 = 3 mm, hp1 = 5 mm, and wp1 = 10 mm.

[0078] (Reference example 2) The PPS resin (B-1) was subjected to injection molding using an injection molding machine (J110AD manufactured by The Japan Steel Works, Ltd.) under the following conditions: injection time: 2 seconds, back pressure: 5 MPa, dwell pressure: 20 MPa, dwell time: 10 seconds, cylinder temperature: 300°C, and mold temperature: 120°C, thereby producing a resin plate shown in 53 in Figure 10. The dimensions were w2 = 80 mm, d2 = 80 mm, and tp2 = 3 mm.

[0079] (Reference example 3) PPS resin (B-1) was subjected to injection molding using an injection molding machine (J110AD manufactured by The Japan Steel Works, Ltd.) under the following conditions: injection time: 2 seconds, back pressure: 5 MPa, dwell pressure: 20 MPa, dwell time: 10 seconds, cylinder temperature: 300°C, and mold temperature: 120°C, thereby producing a resin plate having a unidirectional rib shape as shown in 57 in Figure 11. The dimensions were w3 = 80 mm, d3 = 80 mm, tp3 = 3 mm, hp3 = 5 mm, and wp3 = 10 mm.

[0080] (Reference example 4) An SPCC steel plate (E-1) was prepared as a metal plate common to 51 in Figure 9, 55 in Figure 10, and 60 in Figure 11. The dimensions of each plate were w1 = w2 = w3 = 80 mm, d1 = d2 = d3 = 80 mm, t m1 =t m2 =t m3 =0.5mm.

[0081] (Reference example 5) A Zoltek OXFT (F-1) was prepared, with dimensions of 80 mm width, 80 mm length, and 4.4 mm thickness.

[0082] In addition, t in Figs. a1 , t a2 , t a3 indicates the thickness of the air layer.

[0083] Example 1 The materials used for each part of the lower tray shown in Figure 6 were defined as glass fiber reinforced PPS resin pellets (D-1) for the resin layer, SPCC steel plate (E-1) for the continuous hat-shaped metal layer and the metal layer that also serves as the reinforcing frame, and thermoplastic UD tape (C-1) for the reinforcing material, and the overall weight of the lower tray and the primary natural frequency were calculated by simulation analysis. The results are shown in Table 1.

[0084] Example 2 The materials used for each part of the lower tray shown in Figure 7 were defined as glass fiber reinforced PPS resin pellets (D-1) for the resin layer, and SPCC steel plate (E-1) for the continuous hat-shaped metal layer and the metal layer that doubles as a reinforcing frame, and the overall weight of the lower tray and the primary natural frequency were calculated by simulation analysis. The results are shown in Table 1.

[0085] (Comparative Example 1) The steel lower tray 42 shown in Figure 8 has a first reinforcing frame 43, a second reinforcing frame 44, and a beam 45 on its inner bottom surface, and a third reinforcing frame 46 on its outer bottom surface, and has a shape that can be formed by sheet metal pressing. SPCC steel plate (E-1) was defined as the material used for this lower tray 42, and the overall weight and primary natural frequency of the lower tray were calculated by simulation analysis. The results are shown in Table 1.

[0086] [Table 1]

[0087] Example 3 A hollow rectangular steel column measuring 80 mm in length, 80 mm in width, 3 mm in height, and 0.5 mm in thickness was placed on the metal layer of Reference Example 4, and the resin layer of Reference Example 1 was then placed on top of it to obtain a test specimen with a 3 mm air gap, as shown in Figure 9, which was then subjected to a fire resistance test. The rigidity of the front end and the right end was calculated. The results are shown in Table 2.

[0088] (Comparative Example 2) A test specimen was obtained, a fire resistance test was carried out, and the rigidity was calculated in the same manner as in Example 3, except that the resin layer of Reference Example 2 was used instead of the resin layer of Reference Example 1. The results are shown in Table 2.

[0089] (Comparative Example 3) A test specimen was obtained, a fire resistance test was carried out, and the rigidity was calculated in the same manner as in Example 3, except that the resin layer of Reference Example 3 was used instead of the resin layer of Reference Example 1. The results are shown in Table 2.

[0090] [Table 2]

[0091] Example 4 Except for adjusting the air gap to 0.5 mm, a test specimen was obtained, a fire resistance test was performed, and the rigidity was calculated in the same manner as in Example 3. The results are shown in Table 3.

[0092] Example 5 Except for adjusting the air gap to 1 mm, a test specimen was obtained, a fire resistance test was performed, and the rigidity was calculated in the same manner as in Example 3. The results are shown in Table 3.

[0093] Example 6 Except for adjusting the air gap to 5 mm, a test specimen was obtained, a fire resistance test was carried out, and the rigidity was calculated in the same manner as in Example 3. The results are shown in Table 3.

[0094] Example 7 A test specimen was obtained by placing the flame-resistant yarn mat of Reference Example 5 and the resin layer of Reference Example 1 on the metal layer of Reference Example 4, and a fire resistance test was performed to calculate the rigidity. The results are shown in Table 3.

[0095] Comparative Example 4 A test specimen was obtained in the same manner as in Example 3, except that the resin layer of Reference Example 1 was placed directly on the metal layer of Reference Example 4, and a fire resistance test was carried out, and the rigidity was calculated. The results are shown in Table 3.

[0096] [Table 3]

[0097] As described above, in Examples 1 and 2, battery case lower trays that were both lightweight and rigid were obtained. This was possible because the resin layer in the lower tray had a configuration including a reinforcing shape extending in two directions. On the other hand, Comparative Example 1 was inferior in terms of lightweight properties.

[0098] Furthermore, in a comparison between Example 3 and Comparative Examples 2 and 3, Example 3 had excellent rigidity at both the front end face and the right side end face, and further had excellent fire resistance, with the upper surface temperature in the fire resistance test being below 300°C, which is the melting temperature of the resin. Comparative Example 2 had poor rigidity at both the front end face and the right side end face, and Comparative Example 3 had poor rigidity at the right side end face.

[0099] Furthermore, in a comparison between Examples 4 to 7 and Comparative Example 4, Examples 4 to 7 were excellent in rigidity at both the front end face and the right end face, and no resin melting was observed in the fire resistance test, indicating excellent fire resistance.On the other hand, Comparative Example 4 was poor in both rigidity and fire resistance. [Industrial Applicability]

[0100] The case structure of the present invention is lightweight and has excellent fire resistance, and therefore can be suitably used as a case for a transportation machine part, particularly as a battery case. [Explanation of symbols]

[0101] 1. Resin layer having reinforcing material in a groove shape 2 Groove shape 3 Reinforcement materials 4. Resin layer with reinforcement material in a build-up shape 5. Meat filling shape 6 Case structure with resin layer and metal layer adhesively bonded 7 Ribbed resin layer 8. Hat-shaped metal layer 9. Adhesive 10 Air Layer 11 Case structure in which a resin layer and a metal layer are joined by resin caulking 12 Ribbed resin layer 13 Hat-shaped metal layer 14 Crimping part 15 Case structure with an air layer inclined relative to the horizontal plane 16 Ribbed resin layer 17 Hat-shaped metal layer 18 Adhesive 19 Air Layer 20 Top of the air layer 21 Underside of the air layer 22 Horizontal plane 23 Lower tray of EV drive battery case 24 Box-shaped resin layer 25 Continuous hat-shaped metal layers 26 Metal layer that doubles as a reinforcing frame 27 Thermoplastic UD Tape 28 Hat Shape 29 Boss shape 30 Rib shape that supports the boss shape 31 Joint 32 Air Layer 33 Assembly section 34 Flange 35 Lower tray of EV drive battery case 36 Resin layer 37 Continuous hat-shaped metal layer 38 Metal layer that doubles as a reinforcing frame 39 Isogrid rib shape 40 Joint 41 Air Layer 42 Steel lower tray of EV drive battery case 43 First Frame 44 2nd frame 45 Beam 46 3rd Frame 47 Partial case structure 48 Resin Plate 49 Cross rib shape 50 Air Layer 51 Metal plate 52 Laminated structure of resin plate and metal plate 53 Resin flat plate 54 Air Layer 55 Metal plate 56 Laminated structure of resin plate and metal plate with unidirectional rib shape 57 Resin plate with unidirectional rib shape 58 One-way rib shape 59 Air Layer 60 metal plate S-junction

Claims

1. A case structure for a component to be installed outside the passenger space of a moving body, in which a metal layer and a resin layer are arranged at least in the thickness direction, wherein the metal layer is arranged as the outermost layer, the resin layer has a reinforcing shape extending in at least two directions, the two directions intersecting each other in a plan view extending in a direction perpendicular to the thickness direction in third-angle view, and the reinforcing shape extends in a third direction in the plan view in third-angle view in addition to the two directions, the metal layer and the resin layer are joined to each other at a joint, and an air layer is present between the metal layer and the resin layer in an area excluding the joint.

2. The case structure according to claim 1 , wherein the reinforcing shape is a concave-convex shape.

3. The case structure according to claim 2, wherein a fiber-reinforced thermoplastic resin tape-like sheet made of continuous reinforcing fibers and a thermoplastic resin is disposed on the surface of the uneven shape opposite the metal layer.

4. The case structure according to claim 2 or 3, wherein the uneven shape is a rib shape.

5. The case structure according to claim 2 or 3, wherein the concave and convex shape is a hat shape.

6. The case structure of claim 4 , wherein the rib shape forms a continuous polygon.

7. The case structure according to claim 1 , wherein the air layer is inclined with respect to a horizontal plane based on the width direction and / or the length direction of the case structure.

8. A case structure described in any one of claims 1 to 7, wherein the thickness of the air layer in the thickness direction is 1 mm or more and 3 mm or less.

9. The case structure according to claim 1 , wherein a flame-resistant yarn mat is provided in the air layer.

10. 10. The case structure according to claim 1, wherein the resin layer contains at least one thermoplastic resin selected from the group consisting of polypropylene, polyamide, polycarbonate, polybutylene terephthalate, ABS, and polyphenylene sulfide.

11. The case structure according to claim 1 , wherein the resin layer contains a thermoplastic resin having a melting temperature of 250° C. or higher and 400° C. or lower.

12. 12. The case structure according to claim 1, wherein the resin layer contains at least one type of reinforcing fiber selected from the group consisting of carbon fiber, glass fiber, and organic fiber.

13. 13. The case structure according to claim 1, wherein the joining method for the joint portion is at least one joining method selected from the group consisting of riveting, screw joining, adhesive joining, and welding.

14. A battery case for accommodating a drive battery of an electric vehicle, the battery case having a box-like shape including at least an upper cover and a lower tray, a battery module fixed to an upper surface side of the lower tray, and the upper cover and / or the lower tray including the case structure according to any one of claims 1 to 13.

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