Battery case structure and electric vehicle provided with same

Abstract

[Problem] To provide a battery structure and an electric vehicle equipped with the same, the battery structure being strong even with a simple configuration having a reduced number of components, linearizing a load path to a battery case portion against a side collision input, and allowing a battery loading capacity to be increased. [Solution] A battery case structure loaded with a battery and mounted below a floor of an electric vehicle is constituted by a battery lid having both end portions fixed to side sills, and a battery case mounted on a lower surface of the battery lid, wherein both side surfaces of the battery case are spaced apart from the side sills. The battery lid is positioned below a bottom surface of the floor, or has a structure also serving as the floor.

Description

Battery Case Structure and Electric Vehicle Equipped with the Same 【0001】 The present invention relates to a battery case structure for mounting a battery of an electric vehicle such as an electric car, and particularly has a battery cross member function. Both ends of a battery lid to which a battery case is attached are directly fixed to side sills on both sides in the vehicle width direction, the battery case is separated from the side sills, and the transmission force of a side intrusion input received from the side sills forms a linear load path. The present invention relates to a battery case structure and an electric vehicle equipped with the same. 【0002】 In order to ensure a sufficient driving range, electric vehicles such as electric cars need to mount a large-capacity battery, while a large passenger compartment space is required. To reconcile these two conflicting requirements, in many conventional electric vehicles, a large-capacity battery is loaded into a battery case and mounted below the vehicle floor. Therefore, the battery case for an electric vehicle is required to have high sealing performance to prevent water from entering from the road surface or the like and to prevent malfunctions and failures of electronic components, and high impact strength is required to protect the internal battery. 【0003】 Japanese Patent No. 6734709, Japanese Unexamined Patent Application Publication No. 2023-131343, Japanese Unexamined Patent Application Publication No. 2023-131342, Japanese Unexamined Patent Application Publication No. 2023-16511, U.S. Patent No. 8702161 Specification 【0004】 FIGS. 1 to 3 show a general battery case structure in a conventional electric vehicle. FIG. 1 shows a partial cross-sectional structure and only the right side portion, and shows a structure in which a battery case 21 loaded with a battery 20 is attached to side sills 10A (and 10B) on both sides in the vehicle width direction via side frames 30A (and 30B). Further, FIG. 2(A) is an overall plan view from above the vehicle, FIG. 2(B) is a cross-sectional view taken along line X1-X1 in FIG. 2(A), FIG. 2(C) is a cross-sectional view taken along line X2-X2 in FIG. 2(A), and FIG. 2(D) is a cross-sectional view taken along line X3-X3 in FIG. 2(A). FIG. 3 shows an example of a structure in which the battery case 21 is fixed to the side sill 10A via the side frame 30A in a perspective view of a part of the right side. 【0005】As shown in Figures 1 to 3, the battery case 21, which has a rectangular cross section and a box-shaped case, has multiple (five in this example) battery cross members 22 arranged in the vehicle width direction on its bottom surface as reinforcing members against side impact forces, and the batteries 20 are aligned and loaded between adjacent battery cross members 22. The battery case 21 is connected to the side sills 10A and 10B on both sides of the vehicle via side frames 30A and 30B, and is installed on the lower side of the floor 11 of the electric vehicle. A battery cover 23 is attached to the top surface of the battery case 21 to protect the loaded batteries 20. In addition, multiple (two in this example) floor cross members 12 are suspended between the side sills 10A and 10B on the upper side of the floor 11 as reinforcing members against side impact forces. 【0006】 Since the battery case 21 is positioned on the lower side of the floor 11 and attached to the side sills 10A and 10B via side frames 30A and 30B, gap spaces 31A and 31B are formed between the side sills 10A and 10B and the lower surface of the floor 11. The gap spaces 31A and 31B are formed because, in order to mount the battery case 21 from below the floor 11, the upper surfaces of the side frames 30A and 30B are structured to engage with the lower surfaces of the side sills 10A and 10B, respectively, while ensuring the necessary side sill cross-section for vehicle performance, and considering the ease of mounting the battery 20 to the vehicle, as well as the repairability and maintainability of the battery 20. It is also to ensure that the side frames 30A and 30B serve as energy absorbing members in the event of a side collision. 【0007】 Numerous batteries 20 are arranged and mounted in a battery case 21. Battery cross members 22 are mounted on the battery case 21 via side frames 30A and 30B, spaced apart front to back. Floor cross members 12 are also mounted on the vehicle floor above the battery case 21, spaced apart front to back. Thus, the batteries 20 are structurally protected against side impacts by the battery cross members 22 and the floor cross members 12. 【0008】In this structure, when a side impact input F as shown in Figure 4 is input due to a side collision, the transmitted force F1 is transmitted directly to the vehicle via a straight load path on the floor 11 side, but on the lower battery case 21 side, it is transmitted via the side frame 30A, so the load path acts as a bent transmitted force F2. 【0009】 As described above, in conventional battery structures, the load path receiving side impact input F from the side sills 10A and 10B is received by the side frames 30A and 30B interposed between the battery case 21 and the side sills 10A and 10B, and by the battery cross member 22 inside the battery case 21. Therefore, the side frames 30A and 30B are required, and the battery cross member 22, a separate component, needs to be installed inside the battery case 21, resulting in a large number of parts. 【0010】 The present invention has been made in accordance with the circumstances described above, and the object of the present invention is to provide a battery structure and an electric vehicle equipped therewith that are robust even with a simple configuration that reduces the number of parts, straighten the load path to the battery case in the event of a side impact, and increase the battery capacity. 【0011】 The present invention relates to a battery case structure for mounting a battery under the floor of an electric vehicle. The above objective of the present invention is achieved by comprising a battery lid fixed at both ends to the side sills on both sides of the vehicle, and a battery case mounted on the lower surface of the battery lid, wherein both sides of the battery case are spaced apart from the side sills, and is achieved more effectively by having the battery lid located below the bottom surface of the floor, or by having the battery lid also serve as the floor. 【0012】According to the present invention, the battery lid, which also functions as a battery crossmember, is directly fixed to the side sills on both sides of the vehicle. This eliminates the need for the side frame, which was previously considered essential, and simplifies the structure. Conventionally, when assembling the battery, the side frame is attached from the underside of the vehicle floor as a bracket to support the battery case and the battery cover above it, creating a gap. However, in the present invention, the battery case is completely separated from the side sill and is detachably attached to the underside of the battery lid, with only the battery lid directly fixed to the side sill. Because both sides of the battery case are separated from the side sill, no gap is formed. As a result, the side impact input received from the side sill is directly transmitted to the battery lid, creating a linear load path from the floor (crossmember on the floor) to the battery lid, thus efficiently transmitting the side impact input to the vehicle frame. 【0013】 In conventional designs, the side frame is a component designed to absorb the energy of side impacts. It is generally a rigid structure made of extruded aluminum, and therefore does not necessarily attenuate the side impact force as much as it would if it were applied linearly to the battery case. Furthermore, because the applied side impact force travels along a complex path, absorbing the energy through its structure and material is inefficient, requiring extra costs and components. In contrast, the present invention provides a structure that ensures linear transmission, allowing for the design of an optimal shape and material for energy absorption, thus efficiently resolving the aforementioned problems. Conventionally, when a bending input is applied to the side frame, it becomes prone to bending, and when the side frame bends, the damping force decreases. To prevent the side frame from bending, it must be made of a rigid material and have a thick block shape. However, the battery structure of the present invention receives the side impact input along a linear axis, thus maintaining the damping force, and eliminates the need for a thick block shape, resulting in a simpler structure and weight reduction. 【0014】The battery lid of the present invention is provided with a convex or concave engaging portion, which also functions as a battery cross member. Furthermore, a concave or convex engaging portion is provided at a corresponding position on the battery case, thereby strengthening the battery case through engagement with the battery lid. In addition, in a structure without a convex or concave engaging portion, the flange of the battery case can be made flat, the convex reinforcement portion of the battery lid functions as a battery cross member, it can be used as a floor and a floor cross member can be eliminated. 【0015】 In this way, since there is no need to give the battery case itself strength, the battery case can be made from lightweight materials such as aluminum or synthetic resin. Furthermore, because the battery case is rigidly attached to the battery lid in a removable manner, the battery lid itself can also be used as the floor, contributing to the simplification and weight reduction of the vehicle body structure. 【0016】Figure 1 is a partial cross-sectional view showing an example of a conventional general battery case structure. Figure 2(A) is a plan view showing an example of a conventional general battery case structure, Figure 2(B) is a cross-sectional view along the line X1-X1, Figure 2(C) is a cross-sectional view along the line X2-X2, and Figure 2(D) is a cross-sectional view along the line X3-X3. Figure 3 is a partial perspective view showing an example of the structure of the engagement portion with the side sill of a conventional general battery case structure. Figure 4 is a partial cross-sectional view showing an example of the load path during a conventional side impact. Figure 5 is an exploded view showing the basic structure of the battery case structure according to the present invention. Figure 6 is a cross-sectional development view showing the assembly concept of the battery case structure according to the present invention. Figure 7 is a perspective view showing the details of the battery case. Figure 8(A) is a cross-sectional view along the line Y1-Y1 of the battery case shown in Figure 7, and Figure 8(B) is a cross-sectional view along the line Y2-Y2 of the battery case shown in Figure 7. Figure 9 is a partial perspective view showing a schematic configuration example of the first embodiment (separate floor structure) of the present invention. Figure 10(A) is a structural diagram showing an example of the structure of the first embodiment of the present invention (separate floor structure), and Figure 10(B) is a structural diagram showing the load path in the case of a side impact in the first embodiment. Figure 11 is a partial cross-sectional structural diagram showing details of Figure 9. Figure 12 is a partial perspective view showing a schematic example of the second embodiment of the present invention (integrated floor structure). Figure 13(A) is a structural diagram showing an example of the structure of the second embodiment of the present invention (integrated floor structure), and Figure 13(B) is a structural diagram showing the load path in the case of a side impact in the second embodiment. Figure 14 is a partial cross-sectional structural diagram showing details of Figure 12. Figure 15 is an external perspective view showing an example of a battery case. Figure 16 is an external perspective view showing the battery case with a battery loaded in it, and Figure 17 is a cross-sectional view taken along the line Z1-Z1 in Figure 16. Figure 18 is an external perspective view showing the battery case with a battery loaded in it and a battery lid (first embodiment) mounted on top of it. Figure 19 is a cross-sectional unfolded view showing the mounting structure of the battery case and battery lid. Figure 20 is a cross-sectional view taken along the line Z2-Z2 in Figure 18. Figure 21 is a cross-sectional unfolded view showing an example of mating and engagement between the battery case and the battery lid (second embodiment). Figure 22 is an external perspective view showing the battery case mounted on the battery lid (second embodiment).Figure 23 is an external perspective view showing a battery structure, in which the battery case is attached to the battery lid (first and second embodiments), mounted below the floor. Figure 24 is a cross-sectional view taken along the line Z3-Z3 in Figure 23. Figures 25(A) and (B) are partial cross-sectional views showing examples of mounting the battery case (first embodiment) to the side sill, respectively. Figures 26(A) and (B) are partial cross-sectional views showing examples of mounting the battery case (second embodiment) to the side sill, respectively. Figure 27 is a partial cross-sectional perspective view showing an example of battery loading using the battery lid. Figure 28 is a cross-sectional perspective view showing an example of mounting the battery case to the battery lid. Figures 29(A) and (B) are cross-sectional views showing examples of battery lid reinforcement, respectively. Figure 30 is a perspective view showing an example of patchwork being applied to the inner surface of the convex engaging portion of the battery lid. Figures 31(A) and (B) are schematic diagrams showing the patchwork blank method. Figures 32(A) and (B) are schematic diagrams showing the tailored welded blank method. Figures 33(A) to (C) are schematic diagrams illustrating the tailored welded blank method. Figure 34(A) is a plan view showing a specific structural example of the first embodiment, Figure 34(B) is a cross-sectional view along line V1-V1, Figure 34(C) is a cross-sectional view along line V2-V2, and Figure 34(D) is a cross-sectional view along line V3-V3. Figure 35 is a partial cross-sectional view showing a modified example of the first embodiment. Figure 36(A) is a plan view showing a specific structural example of the second embodiment, Figure 36(B) is a cross-sectional view along line U1-U1, Figure 36(C) is a cross-sectional view along line U2-U2, and Figure 36(D) is a cross-sectional view along line U3-U3. Figure 37 is a perspective view showing another structural example of the battery case. Figure 38 is a perspective view showing another structural example of the battery case. Figure 39 is a perspective view showing another structural example of the battery case. Figures 40(A) and (B) are partial cross-sectional views showing the engagement between the battery case and the battery lid, respectively. Figure 41 is an exploded perspective view showing a modified example of the second embodiment (third embodiment). Figure 42 is a perspective view showing an example of installation of the modified example of the second embodiment (third embodiment). Figure 43 is a cross-sectional view taken along the line W1-W1 in Figure 42. Figure 44 is a perspective view showing an example of the shape of the sealing material. Figures 45(A) and (B) are partial cross-sectional views showing examples of fixing the battery lid, respectively.Figures 46(A) and (B) are cross-sectional views showing other examples of convex muscle tissue, respectively. 【0017】 The present invention relates to a battery case structure for mounting batteries in electric vehicles such as electric cars. In a battery case structure that mounts multiple batteries on the underside of the floor of an electric vehicle, the battery case is formed in a box-like shape by a rectangular bottom plate, side walls perpendicular to the four sides of the bottom plate, and flanges provided around the upper surface of the side walls. Both ends of the battery lid are fixed to the side sills on both sides in the vehicle width direction, and the battery case is firmly attached to the bottom surface of the battery lid via the flanges using mounting members such as bolts and nuts and high-strength bolts, so as to be removable and not detachable. The battery lid is also provided with elongated convex or concave engaging parts that function as battery cross members, and the flanges (side walls) of the battery case that engage with the battery lid are also provided with concave or convex engaging parts at corresponding positions. Furthermore, when the battery case is attached to the battery lid, the convex or concave engaging portion of the battery lid engages with the concave or convex engaging portion of the flange of the battery case, thereby strengthening the battery case. 【0018】 Furthermore, in a structure without convex or concave engaging parts, the flange of the battery case can be made flat, the convex reinforcement of the battery lid functions as a battery cross member, the battery lid can be used as a floor, and the floor cross member can be eliminated. 【0019】 In both cases, both ends of the battery lid are fixed to the side sill, but there is no side frame, and the battery case is spaced apart from both sides of the side sill. Therefore, in the event of a side impact, the force of the impact is not transmitted to the battery case, and the load path is applied only to the battery lid, or to the battery lid and the floor (cross member on the floor), thus allowing the load path to be straightened. 【0020】In the first embodiment of the present invention, the battery lid is located separately below the bottom surface of the floor, while in the second embodiment, the battery lid itself also serves as the floor. In other words, in the first embodiment, the battery lid and the vehicle floor are separated vertically and are separate components, whereas in the second embodiment, the upper surface of the battery lid is an integrated structure that also serves as the vehicle floor. In both the first and second embodiments, the battery case is spaced apart from the side sills on both sides in the vehicle width direction, and in both cases, the load path during a side collision can be straightened. 【0021】 Embodiments of the present invention will be described below with reference to the drawings. 【0022】 Figure 5 shows the basic structure (first and second embodiments) of the battery case structure according to the present invention in exploded view, and Figure 6 shows the assembly concept in cross-sectional unfolded view. Details of the battery case 110 of the present invention are shown in Figure 7, the cross section of the line Y1-Y1 in Figure 7 is Figure 8(A), and the cross section of the line Y2-Y2 is Figure 8(B). 【0023】The battery case 110 consists of a rectangular bottom plate 111, rectangular side walls 112 to 115 perpendicular to the four sides of the bottom plate 111, and a flange 117 extending outward by a predetermined width around the upper surface of the side walls 112 to 115. On both sides of the flange 117 on the vehicle width side, there are opposing engagement notches 116 as concave engaging parts with a rectangular cross-section (or V-shape, U-shape, etc.), and mounting holes 118 are drilled around the periphery. The engagement notches 116 are also connected to the side walls 112 and 114. The battery case 110 does not have a cross member installed, and the batteries 100 are arranged and loaded on the bottom plate 111 of the battery case 110. As shown in Figure 6, the battery case 110 is securely attached to the battery lid 120 via holes 118 in the flange 117 of the battery case 110 using mounting members 130, 131 and 132, 133 such as bolts and nuts, so as to be removable and not detachable. At this time, a sealing material made of an elastic material such as rubber is interposed between the flange 117 and the battery lid 120 to improve the sealing performance. The battery lid 120 is fixed to the side sills 201 and 202 on both sides of the vehicle, and the battery lid 120 is provided with a plurality of convex engaging portions 121 (the same number as on one side of the engaging notches 111), and the strength of the battery case 110 is strengthened when the convex engaging portions 121 fit and engage with each engaging notch 116. 【0024】 Furthermore, the bottom plate 111 of the battery case 110, the side walls 112-115, and the flange 117 may be an integrated structure, or they may be assembled in which the side walls 112-115 are attached to the bottom plate 111, and a rectangular frame-shaped flange is attached to the upper surface of the side walls 112-115. Also, although Figure 6 shows how the battery case 110 is attached on both sides of the vehicle width side by mounting members 130, 131 and 132, 133, in reality, it is also attached to the front and rear of the vehicle (vertical direction of the paper) by mounting members (not shown). 【0025】In the basic structure described above, in the first embodiment of the present invention, as shown in Figures 9 and 10(A), the battery lid 120, on which the battery case 110 carrying the battery 100 is mounted, is located below the floor 204 of the vehicle, and both ends of the battery lid 120 are directly fixed to the side sills 201 and 202. A floor cross member 203 is suspended between the side sills 201 and 202 on the floor 204, as in the conventional design. 【0026】 Because of this structure without a side frame, as shown in Figure 10(B), when there is a side impact input F10 due to a side collision, the side impact input F10 is separated into a linear transmission force F12 that passes through the battery lid 120 fixed to the side sill 201 and a linear transmission force F11 that passes through the floor 204 and the floor cross member 203, and both are linear transmission forces. Figure 11 shows a detail of Figure 10(B), where the side impact input F10 applied to the side sill 201 is separated vertically into a transmission force F12 that passes through the battery lid 120 fixed to the side sill 201 and a transmission force F11 that passes through the floor 204 and the floor cross member 203, and each travels in a straight line. In other words, both transmission forces F11 and F12 have linear load paths. 【0027】 Furthermore, in the second embodiment, as shown in Figures 12 and 13(A), there is no conventional vehicle floor 204, and the battery lid 130, which mounts the battery case 110 on which the battery 100 is installed, also serves as the vehicle floor. In other words, the battery lid 130 is positioned at the floor level, and both ends of the battery lid 130 are directly fixed to the side sills 201 and 202. A floor cross member 203 is suspended between the side sills 201 and 202 on the upper surface of the battery lid 130, as in the conventional design. 【0028】Thus, in the second embodiment as well, there is a structure without a side frame. Therefore, as shown in Figure 13(B), when there is a side impact input F20 due to a side collision, the side impact input F20 is separated into a linear transmission force F22 that passes through the battery lid 130 fixed to the side sill 201 and a linear transmission force F21 that passes through the floor 204 and the floor cross member 203, and both become transmission forces along linear paths. Figure 14 shows a detail of Figure 13(B), where the side impact input F20 applied to the side sill 201 is separated vertically into a transmission force F22 that passes through the battery lid 130 fixed to the side sill 201 and a transmission force F21 that passes through the floor 204 and the floor cross member 203, and each travels in a straight line. In this example, the battery lid 130 also serves as the floor 204. 【0029】 In the second embodiment, a side sill mounting structure is set up, and the assembled battery lid 130 and battery case 110 are mechanically fastened from below. However, if the cross member 203 on the battery lid 130 is attached in this manner, it cannot be fixed to the side sills 201 and 202, so the cross member 203 must be attached to the side sills 201 and 202 beforehand. 【0030】 The following describes the structure of each part common to the first and second embodiments. 【0031】Figure 15 is a perspective view of the battery case 110 positioned between the side sills 201 and 202. The battery case 110 consists of a rectangular bottom plate 111, side walls 112 to 115 perpendicular to the four sides of the bottom plate 111, and a rectangular frame-shaped flange 117 on the top surface. On both sides of the flange 117 on the vehicle width side (vehicle width side) and on the side walls 112 and 114, there are opposing engagement notches 116 that engage with the convex engagement portion of the battery lid 120. In this example, five engagement notches 116 are provided on each side of the flange 117, but the number can be adjusted to match the convex engagement portion. Although not shown in Figure 15, the arrangement and number of holes 118 can also be adjusted as appropriate. Figure 16 is a perspective view of the battery case 110 with the battery 100 loaded, and Figure 17 shows the cross-section along the line Z1-Z1. In this manner, the batteries 100 are aligned on the bottom plate 111 of the battery case 110 and loaded in such a way that they are sandwiched between adjacent convex engaging portions 121 of the battery lid 120. 【0032】 The battery case 110 is firmly attached to the battery lid 120 via a hole 118 in the flange 117 using mounting members 130, 131 and 132, 133, as shown in Figure 6, in a removable manner. At this time, the convex engaging portion 121 of the battery lid 120, which functions as a cross member, fits into and engages with the engaging notches 116 provided on the flange 117 and side walls 112, 114 of the battery case 110. Figure 18 is a perspective view showing the battery case 110 attached to the battery lid 120 of the first embodiment. Both ends of the battery lid 120 on the vehicle width side are fixed to the side sills 201 and 202. Figure 19 shows an unfolded view of its cross-sectional structure, and Figure 20 shows a cross-sectional view along the line Z2-Z2 in Figure 18. As shown in Figure 19, the battery lid 120 of the first embodiment is made of a single sheet metal 122 and has a plurality (five in this example) convex engaging portions 121 formed by press working, and the convex engaging portions 121 are fitted into and engaged with the engaging notches 116 of the flange 117 and the side walls 112, 114. As shown in Figures 19 and 20, the battery 100 is placed on the bottom plate 111 and is stacked by being aligned and sandwiched between adjacent convex engaging portions 121. 【0033】Figure 21 shows the battery lid 120A of the second embodiment, in which a plurality (five in this example) of elongated convex engaging portions 123 are vertically provided on the bottom surface of the rectangular flat plate 124. The convex engaging portions 123 are shaped to engage by fitting into the engaging notches 116 of the flange 117 and side walls 112, 114, as in the first embodiment. Figure 22 shows the state in which the battery case 110 is attached to the battery lid 120A (second embodiment), and in this example using the second embodiment, the top surface of the battery lid 120A is flat. 【0034】 As described above, Figure 23 shows the battery lid 120 (or 120A) with the battery case 110 attached mounted on the vehicle, and Figure 24 shows the cross section along line Z3-Z3. Figure 24 shows an example of the battery lid 120 of the first embodiment, but the cross-sectional structure of the battery lid 120A of the second embodiment is almost identical. The battery case 110 mounted on the bottom surface of the battery lid 120 is positioned below the vehicle floor 204, and both sides of the battery lid 120 are fixed to the side sills 201 and 202. Above the floor 204, multiple (two in this example) floor cross members 203 are suspended between the side sills 201 and 202. 【0035】 Figures 25(A) and (B) schematically show the method of fixing the battery lid 120 (first embodiment) with the battery case 110 attached to the side sills 201 and 202, with Figure 25 showing only the side sill 201 for convenience. In the example of Figure 25(A) according to the first embodiment, the side sill 201 is provided with an inwardly protruding hollow engaging body portion 201A, the upper surface of the battery lid 120 is brought into contact with the bottom of the engaging body portion 201A, and it is fastened and fixed with fastening members 141 and 142 such as bolts, nuts, and rivets. In the example of Figure 25(B) according to the first embodiment, the side portion of the battery lid 120 is provided with a bent portion that is bent downward, the bent portion is brought into contact with the outer surface of the side sill 201, and it is fastened and fixed with fastening members 143 and 144 such as bolts, nuts, and rivets. 【0036】Figures 26(A) and (B) schematically show the method of fixing the battery lid 130 (second embodiment) with the battery case 110 attached to the side sills 201 and 202, with Figure 26 showing only the side sill 201 for convenience. In the example of Figure 26(A) according to the second embodiment, the side sill 201 is provided with an inwardly protruding hollow engaging body portion 201B, and the upper surface (floor surface) of the battery lid 130 is brought into contact with the bottom of the engaging body portion 201B and fastened and fixed with fastening members 151 and 152 such as bolts, nuts, and rivets. In the example of Figure 26(B) according to the second embodiment, both ends of the battery lid 130 are provided with bent portions that are bent downward, and the bent portions are brought into contact with the outer surface of the side sill 201 and fastened and fixed with fastening members 153 and 154 such as bolts, nuts, and rivets. 【0037】 Furthermore, when fastening the battery lids 120, 120A, and 130, in addition to fastening with bolts, nuts, rivets, and other fastening members, adhesives may also be used. Also, in the second embodiment, when using the battery lid 120 of the first embodiment shown in Figure 19, the recess of the convex engaging portion 121 will be exposed on the upper surface of the battery lid 120, i.e., on the floor surface, so a mat or the like may be laid down to ensure aesthetics. 【0038】 As described above, the battery lid 120 (first embodiment) is made of a single sheet metal 122, and multiple convex engaging portions 121 are provided on the sheet metal 122 by press working or the like. Therefore, it is undesirable for the convex engaging portions 121 to deform during fitting into the engaging notch 116, engaging, or housing the battery 100, so it is necessary to reinforce the convex engaging portions 121. A method for doing so will be described below. 【0039】Figure 27 is a cross-sectional perspective view showing a structure in which a number of batteries 100 are held by being sandwiched between adjacent convex engaging portions 121 of the battery lid 120, and Figure 28 is a perspective view showing a structure in which the convex engaging portions 121 engage by fitting into the engaging notches 116 of the flange 117 and the side walls 112 and 114. Figure 29(A) is an example in which the inner recess of the convex engaging portion 121 is reinforced by patchwork 125, and the whole structure is shown in perspective view of Figure 30. Figure 29(B) shows an example in which the inner recess of the convex engaging portion 121 is reinforced by tailored 126. 【0040】 To prevent intrusion into the battery 100 from a side impact, it is desirable that the convex engaging portion 121 does not deform. To prevent deformation, the convex engaging portion 121 needs to have increased plate thickness or high strength material to increase its rigidity or strength. However, increasing the plate thickness of the entire battery lid 120 (122 in Figure 29) would increase its weight. Therefore, by reinforcing only the convex engaging portions 121 and 123, which are to be made rigid or strong, using high strength material and thick plates, as shown in Figure 29(A) using patchwork (a method in which blank plates that will serve as reinforcing parts are assembled on the battery lid before press molding, and then molded into reinforcing parts at the same time as the battery lid is molded), or by using high strength material and thick plates tailored as shown in Figure 29(B) using thick plates, it is possible to reduce weight while suppressing intrusion from a side impact. 【0041】 Figure 31 is a schematic diagram illustrating the patchwork blanking method, in which small steel plates (patches) 160 are attached in a lap-like manner using laser welding or spot welding to locally reinforce the steel plate 161. Schematic diagrams in Figures 32 and 33 illustrate the tailored welded blanking method. In Figure 32, two steel plates 170 and 171 of different thicknesses and materials are welded together before press forming to form a single blank. In Figure 33, three steel plates 173 to 175 of different materials are laser-welded or spot-welded together before press forming to form a single blank. 【0042】FIG. 34 shows a specific structural example (first embodiment) in which the battery case 110 of the present invention is mounted below the floor 204. FIG. 34(A) is a plan view, FIG. 34(B) is a cross-sectional view taken along line V1-V1 of FIG. 34(A), FIG. 34(C) is a cross-sectional view taken along line V2-V2 of FIG. 34(A), and FIG. 34(D) is a cross-sectional view taken along line V3-V3 of FIG. 34(A). 【0043】 In order to strengthen the battery structure of the present invention, as shown in FIG. 35, the end of the battery lid 120 may be partially softened or a low-strength material may be tailored. At the same time, the end of the floor upper cross member 203 may be similarly partially softened or a low-strength material may be tailored. 【0044】 When the necessary impact absorption cannot be obtained in the side sill cross section, large strain concentration occurs on the center side of the floor upper cross member 203 and the convex engaging portion 121, and deformation occurs. By partially softening and reducing the strength of the end portion, impact absorption can be performed, and the occurrence of large strain concentration on the center side of the floor upper cross member 203 and the convex engaging portion 121 can be suppressed, and deformation can be suppressed. 【0045】 FIG. 36 shows a specific structural example (second embodiment) in which the battery lid 120 equipped with the battery case 110 of the present invention is mounted so as to also serve as a floor. FIG. 36(A) is a plan view, FIG. 36(B) is a cross-sectional view taken along line U1-U1 of FIG. 36(A), FIG. 36(C) is a cross-sectional view taken along line U2-U2 of FIG. 36(A), and FIG. 36(D) is a cross-sectional view taken along line U3-U3 of FIG. 36(A). 【0046】 In the above-mentioned battery case 110, a rectangular flange 117 is provided on the upper surface of the case. However, as shown in FIG. 37, a structure in which separated rectangular flanges 117-1 to 117-4 corresponding to the respective side walls 112 to 115 are provided so that four corners become spaces may also be used. 【0047】In addition, in the above description, a convex engaging portion is provided on the battery lid 120 (120A, 130), and notch 116 is provided on the flange 117 and side walls 112, 114 of the battery case to enhance the strength by fitting and engaging the concave-convex structure. On the contrary, as shown in FIG. 38, the flange 117B may be made flat and the bottom of the battery lid may also be made flat, and the battery case may be mounted on the battery lid. Although this example will be illustrated and described later, even in this case, the load path of the side intrusion input can be linearized in the same manner. 【0048】 Furthermore, in the above description, a convex engaging portion is provided on the battery lid 120 (120A, 130), and notch 116 as a concave engaging portion is provided on the flange 117 and side walls 112, 114 of the battery case. However, the concave-convex structure may have the reverse relationship. That is, as shown in FIG. 39, a protrusion 119 as a convex engaging portion is provided on the upper surface of the flange 117, and the structure is the same as that of the battery lid 180 (third embodiment) shown in FIG. 40(A) or the battery lid 180A (fourth embodiment) shown in FIG. 40(B). In the battery lid 180 of the third embodiment, the concave engaging portion 182 is formed of a single plate of sheet metal. In the battery lid 180A of the fourth embodiment, the concave engaging portion is formed of a pair of protruding members 184, 185 vertically provided on a flat plate-like member 183. 【0049】 Even with the fitting and engagement between the concave engaging portion of such a battery lid 180 (180A) and the convex engaging portion 119 of the flange 117 of the battery case, the same effect can be obtained. 【0050】 In the above description, an embodiment in which the battery lid and the battery case are engaged with each other in a concave-convex structure relationship has been described. However, a third embodiment using a battery case 110B with a flat flange 117 as shown in FIG. 38 will be described. In this third embodiment, since the battery lid 190 also serves as the floor 204, it can be said to be a modification of the second embodiment. 【0051】Figure 41 is an exploded perspective view showing this embodiment. In this embodiment, the battery case 110B shown in Figure 38 is used. The flange 117 of the battery case 110B has a flat structure without irregularities and is equipped with holes 118 for mounting to the battery lid 190 with a mounting member. The battery lid 190 is equipped with a rectangular flat frame 192 and multiple convex reinforcing bars 191 perpendicular to the side sills 201 and 202. The convex reinforcing bars 191 function as battery cross members, and the cross-sectional shape of the convex reinforcing bars 191 is trapezoidal as shown in Figure 43, with a recessed bottom surface 194 between adjacent convex reinforcing bars 191. The frame 192 is also provided with holes 193 corresponding to the holes 118 of the flange 117. Figure 42 shows the battery case 110B mounted on the battery lid 190, and Figure 43 shows the cross-sectional structure along the line W1-W1. In this example as well, when the battery case 110B is attached to the battery lid 190, a sealing material 230 is interposed between the mounting surfaces. In this example, the upper surface of the flange 117 is flat and the back surface of the frame 192 is flat, so the shape of the sealing material 230 is a rectangular plate material as shown in Figure 44, corresponding to the frame 192 and the flange 117. The sealing material 230 is also provided with holes 231 for passing mounting members such as bolts. 【0052】 In this embodiment, the battery lid 190 also serves as the floor, and the convex reinforcement portion 191 functions as a battery cross member, so it is not necessary to provide a cross member on the floor. 【0053】The battery lid 190, with the battery case 110B attached, is fixed to the side sills 201 and 202 by the method shown in Figure 45(A) or Figure 45(B). In either case, the energy absorbing member 210 is interposed between the upper side surface of the battery case 110B and the side sill 201 and fixed to the side sill 201 via an L-shaped bracket. Specifically, in the example of Figure 45(A), the upper part of the energy absorbing member 210 is fastened to the battery case 110B and the battery lid 190 by a fastening member 211, and also fastened to the flat portion of the bracket 220 by a fastening member 212. The vertical portion of the bracket 220 is fastened to the side sill 201 by a fastening member 213. On the other hand, in the example shown in Figure 45(B), the upper part of the energy absorbing member 210 is fastened to the battery case 110B and the battery lid 190 by a fastening member 214, the lower part is fastened to the flat surface of the bracket 221 by a fastening member 216, and the vertical part of the bracket 221 is fastened to the side sill 201 by a fastening member 215. 【0054】 Although the side sill 201 has been described here, the same applies to the side sill 202. Furthermore, while the cross-sectional shape of the convex reinforcement portion 191 of the battery lid 190 is described as trapezoidal above, it may also be U-shaped as shown in Figure 46(A) or V-shaped as shown in Figure 46(B). 【0055】10A, 10B Side sill 11 Floor 12 Floor cross member 20 Battery 21 Battery case 22 Battery cross member 23 Cover 30A, 30B Side frame 31A, 31B Gap space 100 Battery 110, 110A, 110B, 110C Battery case 111 Bottom plate 112-115 Side wall 116 Engaging notch 117 Flange 118, 193 Hole 119 Projection 120, 120A, 130, 180, 180A, 190 Battery lid 121, 123 Convex engaging part 201, 202 Side sill 203 Floor cross member 204 Floor 210 Energy absorbing member 211-216 Fastening member 220, 221 Bracket 230 sealing material

Claims

1. A battery case structure for mounting a battery under the floor of an electric vehicle, characterized in that it comprises a battery lid fixed at both ends to the side sills on both sides of the vehicle, and a battery case mounted on the lower surface of the battery lid, wherein both sides of the battery case are spaced apart from the side sills.

2. The battery case structure according to claim 1, wherein the battery case is a box-shaped case with a rectangular cross-section, and a flange extending outward is formed on the periphery of the upper surface, and the battery case is detachably attached to the battery lid via the flange by a mounting member.

3. The battery case structure according to claim 1 or 2, wherein when a side impact is applied to the side sill, the force transmitted by the side impact is applied linearly to the battery lid, the floor and the floor cross member, and the load path is straightened.

4. The battery case structure according to claim 3, wherein a sealing material is interposed between the battery lid and the flange.

5. The battery case structure according to claim 4, wherein the mounting member is a bolt and nut or a high-strength bolt.

6. The battery case structure according to claim 4, wherein a convex engaging portion having the function of a battery cross member is formed on the lower surface side of the battery lid, and concave engaging portions are formed on both side walls of the flange and the battery case, and the convex engaging portion is fitted into the concave engaging portion to engage.

7. The battery case structure according to claim 4, wherein a concave engaging portion having the function of a battery cross member is formed on the lower surface side of the battery lid, and a convex engaging portion is formed on the upper surface of the flange, and the convex engaging portion is fitted into the concave engaging portion to engage.

8. The battery case structure according to claim 6, wherein the convex engaging portion of the battery lid is formed from a single sheet of metal.

9. The battery case structure according to claim 6, wherein the convex engaging portion of the battery lid is formed by a projection member perpendicularly attached to a flat plate-shaped member.

10. The battery case structure according to claim 7, wherein the recessed engaging portion of the battery lid is formed from a single sheet of metal.

11. The battery case structure according to claim 7, wherein the recessed engaging portion of the battery lid is formed by a pair of projection members perpendicularly attached to a flat plate-shaped member.

12. The battery case structure according to claim 6 or 7, wherein the battery lid is located below the bottom surface of the floor.

13. The battery case structure according to claim 6 or 7, wherein the battery lid also serves as the floor.

14. The battery case structure according to claim 6, wherein the convex engaging portion of the battery lid is patchwork-processed.

15. The battery case structure according to claim 6, wherein the convex engaging portion of the battery lid is tailored.

16. The battery case structure according to claim 1 or 2, wherein the battery lid is provided with a convex reinforcing portion having a cross member function, the flange is flat, and the battery lid also serves as the floor.

17. The battery case structure according to claim 16, wherein an energy absorbing member is interposed between the side sill and the battery lid.

18. The battery case structure according to claim 17, wherein the battery lid and the energy absorbing member are fixed to the side sill via an L-shaped bracket.

19. The battery case structure according to claim 16 or 17, wherein there is no floor cross member, and when a side impact is applied to the side sill, the transmission force of the side impact is applied linearly to the battery lid and the convex reinforcement portion, and the load path is straightened.

20. An electric vehicle characterized by comprising the battery case structure described in any one of claims 1 to 19.

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