Vehicle structure

Abstract

This vehicle structure is located under the center of the vehicle body and includes a battery cover, a battery tray, and a structural member A that absorbs impact energy. The battery cover and battery tray are each made of integrally molded fiber-reinforced plastic. Structural member A is located at least on the outer side of the battery cover and battery tray in the vehicle width direction. Structural member A is fastened together with the battery cover and battery tray.

Description

Technical Field

[0001] The present invention relates to a vehicle structure including a battery tray disposed at a lower center of a vehicle body, a battery cover, and a structural member that absorbs impact energy.

Background Art

[0002] In electric vehicles, since in-vehicle batteries occupy a considerable weight and mounting space, much research has been conducted on the structure of in-vehicle batteries. In Patent Document 1, a case for housing a battery is made of a fiber-reinforced plastic to reduce the weight of the battery tray. Patent Document 2 describes a battery box in which the strength and rigidity of a battery tray are enhanced by a metal frame-shaped frame. Patent Document 3 describes a component for absorbing impact energy disposed outside the battery in the vehicle width direction to protect the battery housed in an electric vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the case of the battery tray described in Patent Document 1, the battery tray has a single-layer structure for absorbing impact energy, and the airtightness of the battery box is lost during a collision. As a result, the battery is damaged by rainwater or the like, and there is a risk of explosion or the like.

[0005] In the case of the battery tray described in Patent Document 2, when the side surface of the vehicle is impacted, the metal frame-shaped frame is likely to be deformed by an external force, and the battery may be damaged.

[0006] Since the shock-absorbing structural member described in Patent Document 3 is fastened to the vehicle body side instead of the battery box, the structural rigidity of the battery tray and the battery cover cannot be utilized at all.

[0007] The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a vehicle structure in which a structural member is jointly fastened together with a battery tray and a battery cover.

Means for Solving the Problems

[0008] As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention.

[0009] 1. A vehicle structure disposed at the lower part of the center of the vehicle body, comprising: a battery cover, a battery tray, and a structural member for absorbing impact energy, wherein the battery cover and the battery tray are each made of integrally formed fiber-reinforced plastic, the structural member is located outside at least one of the battery cover and the battery tray in the vehicle width direction, and the structural member is jointly fastened together with the battery cover and the battery tray.

[0010] 2. The vehicle structure according to 1 above, wherein the structural member is jointly fastened together with the battery tray and the battery cover by a stepped bolt.

[0011] 3. The vehicle structure according to 2 above, wherein the battery cover, the battery tray, and the structural member are stacked and jointly fastened in this order.

[0012] 4. The structural member, the battery cover, and the battery tray are stacked in this order and jointly fastened, the vehicle structure according to 2 above.

[0013] 5. The structural member has a first longitudinal wall and a second longitudinal wall located inside the first longitudinal wall in the vehicle width direction. The first longitudinal wall and the second longitudinal wall extend in the longitudinal direction of the vehicle body. The minimum thickness of the first longitudinal wall is smaller than the maximum thickness of the second longitudinal wall, the vehicle structure according to any one of 1 to 4 above.

[0014] 6. The battery cover and the battery tray are each composed of a fiber-reinforced plastic integrally formed using a sheet molding compound, the vehicle structure according to any one of 1 to 5 above.

[0015] 7. A cross member is inserted into the battery tray. (1) The battery tray has a first bottom portion, a peripheral wall erected on the outer periphery of the first bottom portion, a first inner wall connected to the first bottom portion, a second inner wall connected to the first bottom portion, and a second bottom portion connected to both the first inner wall and the second inner wall and erected from the first bottom portion. (2) The first bottom portion, the peripheral wall, the first inner wall, the second inner wall, and the second bottom portion are composed of an integrally formed fiber-reinforced plastic. (3) A recess extending in the vehicle width direction is formed by the first inner wall, the second inner wall, and the second bottom portion, and the cross member is inserted into at least one location of the recess, the vehicle structure according to any one of 1 to 6 above.

[0016] 8. The cross member is joined to the structural member, the vehicle structure according to 7 above.

[0017] 9. The angle formed between the first bottom portion and the first inner wall, and the angle formed between the first bottom portion and the second inner wall are 90 degrees or more and 135 degrees or less, the vehicle structure according to 7 or 8 above.

[0018] 10. In the boundary regions between the first bottom and the first inner wall, between the first bottom and the second inner wall, and between the first bottom and the peripheral wall, discontinuous fibers are continuously dispersed. The vehicle structure according to any one of the above 7 to 9.

[0019] 11. The battery cover has ribs, and the natural frequency of the primary mode is 25 Hz or more. The vehicle structure according to any one of the above 1 to 10.

[0020] 12. The fiber-reinforced plastic has a specific heat of 0.5 J / kg·°C or more and 2.0 J / kg·°C or less, and a minimum thickness of 1 to 5 mm. The vehicle structure according to the above 1.

[0021] 13. A battery-mounted vehicle body obtained by fixing the vehicle structure according to any one of the above 1 to 12 to a vehicle body, wherein the relationship between the number of fixing points n1 between the structural member and the vehicle body and the number of fixing points n2 between the battery cover and the vehicle body satisfies n1 > n2. A battery-mounted vehicle body.

[0022] 14. The lowermost part of the structural member is located below the lowermost part of the battery tray. The vehicle structure according to any one of the above 1 to 13.

[0023] 15. The upper end of the first vertical wall of the structural member is located above the first bottom of the battery tray, and the lower end of the first vertical wall of the structural member is located below the first bottom of the battery tray. The vehicle structure according to the above 5.

[0024] 16. The upper end of the second vertical wall of the structural member is located above the first bottom of the battery tray, and the lower end of the second vertical wall of the structural member is located below the first bottom of the battery tray. The vehicle structure according to the above 5.

[0025] 17. The vehicle structure according to claim 14, further comprising a protective wall below the battery tray, the protective wall being connected to the structural member.

[0026] 18. The structural member includes a first longitudinal wall and a second longitudinal wall located inside the first longitudinal wall in the vehicle width direction. The first longitudinal wall and the second longitudinal wall extend in the longitudinal direction of the vehicle body. The vehicle structure according to any one of claims 1 to 5, wherein the strength of the first longitudinal wall is lower than the strength of the second longitudinal wall.

Effect of the Invention

[0027] In the vehicle structure of the present invention, when an impact is applied to the side of the vehicle, in addition to the structural rigidity of the vehicle body, the structural rigidity of the battery tray can be utilized.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 6

Figure 7A

Figure 7B

Figure 7C

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out the Invention

[0029] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto. The vehicle structure of the present invention is a vehicle structure arranged at the lower part of the center of the vehicle body, and includes a battery box having a battery tray and a battery cover, and a structural member that absorbs impact energy. The battery tray and the battery cover are each made of integrally molded fiber-reinforced plastic.

[0030] [Integrally Molded] Here, "integral molding" means molding continuously without joints, rather than joining separate members for molding. Such integral molding can be achieved by manufacturing fiber-reinforced plastics in a single molding process, and preferably, it can be achieved by press molding. Fiber-reinforced plastics can be manufactured by integrally molding sheet molding compound (also referred to as SMC). By integrally molding parts, different parts can be treated as one part, and the unit price of the parts can be reduced. Also, the number of assembly man-hours can be reduced, and the cost related to inventory can be reduced by reducing the number of parts. Note that the battery tray and the battery cover are each integrally molded, and the battery tray is not integrally molded with the battery cover. The battery tray and the battery cover are separate bodies.

[0031] [Fiber Reinforced Plastics] 1. Reinforcing Fibers The reinforcing fibers contained in the fiber-reinforced plastics are not particularly limited, but are preferably one or more reinforcing fibers selected from the group consisting of carbon fibers, glass fibers, aramid fibers, boron fibers, and basalt fibers. It is more preferable that the reinforcing fibers are glass fibers. When using glass fibers as the reinforcing fibers, the average fiber diameter of the glass fibers is preferably 1 μm to 50 μm, and more preferably 5 μm to 20 μm. When the average fiber diameter is large, the impregnation of the resin into the fibers becomes easy, and when it is below the upper limit, the moldability and processability are improved.

[0032] 2. Discontinuous Fibers The reinforcing fibers preferably include discontinuous fibers. When using discontinuous fibers, the moldability is improved compared to fiber-reinforced plastics using only continuous fibers, and it is easy to mold complex molded products.

[0033] 3. Weight Average Fiber Length of Reinforcing Fibers The weight average fiber length of the reinforcing fibers is preferably 1 mm or more and 100 mm or less. The weight average fiber length is more preferably 1 mm to 70 mm, and even more preferably 1 mm to 50 mm.

[0034] In recent years, in-vehicle batteries have been increasing in size, and the vertical and horizontal dimensions of battery boxes are, for example, 1 m × 1 m, 1.5 m × 1.5 m, etc. If the weight average fiber length is 1 mm or more, even when manufacturing a large battery box, it is easy to ensure the mechanical properties for storing a large battery.

[0035] In fiber-reinforced plastics manufactured by injection molding, the weight average fiber length of the reinforcing fibers is about 0.1 to 0.3 mm. Therefore, when the weight average fiber length of the reinforcing fibers is 1 mm or more and 100 mm or less, it is preferable to manufacture the fiber-reinforced plastics by press molding.

[0036] When the weight average fiber length of the reinforcing fibers is 100 mm or less, it is preferable because of excellent fluidity. In the present invention, discontinuous reinforcing fibers having different fiber lengths may be used in combination. That is, the discontinuous reinforcing fibers used in the present invention may have a single peak in the weight average fiber length distribution, or may have a plurality of peaks.

[0037] 4. Fiber volume ratio The fiber volume ratio Vf of the reinforcing fibers is not particularly limited, but is preferably 20 to 70%, more preferably 25 to 60%, and even more preferably 30 to 55%. The fiber volume ratio (Vf, unit: volume %) refers to the ratio of the volume of the reinforcing fibers to the total volume of the fiber-reinforced plastics including not only the reinforcing fibers and the matrix resin but also other additives.

[0038] 5. Resin In the present invention, the type of resin is not particularly limited, and a thermosetting resin or a thermoplastic resin is used. When using a thermosetting resin, the thermosetting resin is preferably an unsaturated polyester resin, a vinyl ester resin, an epoxy resin, or a phenolic resin. The resin may be used alone or in combination of two or more.

[0039] 6. Other agents The fiber-reinforced plastic used in the present invention may contain various fibrous or non-fibrous fillers such as organic fibers or inorganic fibers, inorganic fillers, flame retardants, ultraviolet resistant agents, stabilizers, mold release agents, pigments, softening agents, plasticizers, surfactants, etc., as long as the object of the present invention is not impaired. When using a thermosetting resin, a thickener, a curing agent, a polymerization initiator, a polymerization inhibitor, etc. may be contained. The additives may be used alone or in combination of two or more.

[0040] 7. Sheet Molding Compound The fiber-reinforced plastic of the present invention is preferably obtained by molding a sheet molding compound (also referred to as SMC) using reinforcing fibers. Since the sheet molding compound of the present invention has high moldability, it can be easily molded into a complex shape such as a battery tray or a battery cover.

[0041] That is, a fiber-reinforced plastic can be produced by molding a sheet molding compound, and a battery tray having unevenness can be produced. The sheet molding compound has higher fluidity and moldability than continuous fibers, and ribs and bosses can be easily produced. As the fiber-reinforced plastic using a sheet molding compound (SMC), the sheet molding compound manufactured by Continental Structural Plastics (sometimes abbreviated as CSP) can be used.

[0042] [Minimum Thickness of Fiber-Reinforced Plastic] In the present invention, the minimum thickness of the fiber-reinforced plastic is preferably 1.0 mm or more and less than 5 mm, more preferably 1.5 mm or more and less than 5 mm, still more preferably 2 mm or more and 5 mm or less, and even more preferably 3 mm or more and 5 mm or less. If the minimum thickness is 5 mm or less, it is preferable from the viewpoint of weight reduction of the battery box. If the minimum thickness of the fiber-reinforced plastic is 1.0 mm or more, the battery temperature is less likely to be affected by the outside air temperature.

[0043] In the case of the battery tray, the minimum thickness of the fiber-reinforced plastic is preferably 2 mm or more and less than 5 mm, and more preferably 3 mm or more and less than 5 mm. In the case of the battery cover, the minimum thickness of the fiber-reinforced plastic is preferably 1 mm or more and less than 4 mm, and more preferably 1 mm or more and less than 3 mm.

[0044] [Specific Heat of Fiber-Reinforced Plastic] The specific heat of the fiber-reinforced plastic is preferably 0.5 J / kg·°C or more and 2.0 J / kg·°C or less. Within this range, the influence of the outside air temperature on the battery is reduced. Hereinafter, an embodiment of the vehicle structure of the present invention will be described with reference to the drawings.

[0045] The vehicle structure shown in the drawings is disposed at the lower center of the vehicle body and includes a battery box 101 including a battery tray 105 and a battery cover 102, and a structural member A (108). The battery tray 105 and the battery cover 102 are each made of integrally formed fiber-reinforced plastic. The structural member A (108) is used to absorb impact energy. The battery box 101 houses a battery 103. Further, the battery tray 105 may be provided with a cooling mechanism 104 for temperature control. The battery cover 102, the battery tray 105, and the structural member A (108) are clamped together. The clamped state is shown in FIG. 6.

[0046] When the components of the battery box are made of fiber-reinforced plastic, an electromagnetic wave shielding layer is attached to the battery box to shield the electromagnetic waves generated from the battery. The electromagnetic wave shielding layer can shield the electromagnetic waves radiated from the battery to prevent external radiation and leakage, and can ensure sufficient electromagnetic wave shielding performance for the components of the battery box. For example, it can prevent the adverse effects of electromagnetic waves on the vehicle control system and the human body.

[0047] The electromagnetic wave shielding layer is preferably made of metal, and more preferably made of aluminum or an aluminum alloy. The electromagnetic wave shielding layer may be clamped together with the battery cover 102, the battery tray 105, or the structural member A (108).

[0048] [Battery Tray and Battery Cover] The battery 103 is housed in the battery box 101 having the battery tray 105 and the battery cover 102.

[0049] [Natural Vibration Frequency of the Primary Mode of the Battery Cover] The battery cover 102 has ribs such as the rib 702 shown in FIG. 7C, and the natural frequency of the primary mode is preferably 25 Hz or more. The natural frequency is more preferably 30 Hz or more, still more preferably 35 Hz or more, and even more preferably 40 Hz or more. When the battery cover 102 includes ribs, the battery cover 102 has a structure with a non-uniform thickness. Since the vibration input to the battery cover 102 is often 25 Hz or less, it is preferable to design the battery cover 102 so as not to resonate with the vibration. The cross-sectional shape of the rib is not particularly limited, and may be a square shape, a rectangular shape, an inverted frustum shape, an inverted triangular shape, a semi-circular cross-sectional shape, a semi-elliptical cross-sectional shape, an uneven shape, a mountain shape, or the like. The arrangement structure of the ribs is not particularly limited, and they may be arranged in one direction, crosswise, or obliquely. The position of the rib is also not particularly limited, and it may be on the outside or inside of the battery cover 102. Providing ribs on the inside is preferable because it can maximize the design space of the battery box 101 (for example, the design space can be utilized for wiring between the ribs). FIG. 8 shows a cross-shaped rectangular rib 802 provided inside the battery cover 102. Since the battery tray 105 has a recess, the natural frequency of the primary mode can be easily set to 25 Hz or more.

[0050] [Number of fixing points between the battery cover and the vehicle body] If the natural frequency of the primary mode of the battery cover 102 is less than 25 Hz, it is necessary to fix the battery cover 102 to the vehicle body in order to prevent resonance with the vibration input to the battery cover 102, and the number of fixing points to the vehicle body increases. That is, if the natural frequency of the primary mode is 25 Hz or more, the number of fixing points for fixing the battery cover 102 to the vehicle body can be reduced in order to prevent resonance with the vibration input to the battery cover 102. Generally, the battery cover 102 is fixed by being fastened from the inside of the vehicle body. If the number of fixing points can be reduced, the fastening work from the inside of the vehicle body can be reduced.

[0051] That is, when the vehicle structure of the present invention is fixed to the vehicle body and the vehicle body becomes a battery-mounted vehicle body, it is preferable that the relationship between the number n1 of fixing points between the structural member A (108) and the vehicle body and the number n2 of fixing points between the battery cover 102 and the vehicle body satisfies n1 > n2. The fixing points between the structural member A (108) and the vehicle body are shown at 1201 in FIG. 12.

[0052] By fastening the structural member A (108) to the vehicle body, the number of fixing points (mainly fastening) for fixing the battery cover 102 to the vehicle body can be reduced. When fastening the structural member A (108) to the vehicle body, it is not necessary to fasten the battery cover 102 from the inside of the vehicle body, so the work efficiency is improved. Specifically, the number n2 of fixing points is preferably 10 or less, more preferably 5 or less, still more preferably 3 or less, and most preferably 0. Also, by reducing the number of fixing points of the battery box 101, the number of fastening holes of the battery box 101 can be reduced. Therefore, the airtightness of the battery box 101 can be easily ensured.

[0053] [Battery Tray: General] The battery tray 105 mounts the vehicle drive battery 103 and is used to drive an automobile. The battery tray 105 has a first bottom portion 303 and a peripheral wall 205 erected on the outer periphery of the first bottom portion 303. The battery tray 105 further includes a first inner wall 206 connected to the first bottom portion 206, a second inner wall 207 connected to the first bottom portion 303, and a second bottom portion 301 that is connected to both the first inner wall 206 and the second inner wall 207 and is raised from the first bottom portion.

[0054] The first bottom portion 303, the peripheral wall 205, the first inner wall 206, the second inner wall 207, and the second bottom portion 301 are made of integrally molded fiber-reinforced plastic. In this way, since the internal partition wall 107 is formed by the first inner wall 206 and the second inner wall 207, even if the internal partition wall is formed high from the bottom, a wall containing reinforcing fibers can be easily manufactured up to the tip.

[0055] [Battery Tray: Flange] The battery tray 105 has, for example, a flange 402 shown in FIG. 4. The flange of the battery tray 105 is used for co-fastening the battery cover 102 and the structural member A (108).

[0056] [Battery Tray: First Bottom] The lower surface of the first bottom 303 is the lowermost surface of the battery tray 105. A battery may be placed on the upper surface of the first bottom 303, or a cooling mechanism 104 or a ventilation mechanism may be provided in the space provided between the battery and the first bottom. Further, the first bottom does not have to be completely flat, and may be wavy like a corrugated shape or may have a curved surface.

[0057] [Battery Tray: Peripheral Wall] The peripheral wall 205 is erected on the outer periphery of the first bottom 303 and is preferably formed continuously on the surface of the first bottom 303.

[0058] [Battery Tray: First Inner Wall and Second Inner Wall] The first inner wall 206 is connected to the first bottom 303. The fiber-reinforced plastic constituting the battery tray is bent between the first inner wall 206 and the first bottom 303. The first bottom 303 is continuous with the first inner wall 206, and the first bottom 303 and the first inner wall 206 are integrally formed without a joint.

[0059] Similarly, the second inner wall 207 is connected to the first bottom 303. The fiber-reinforced plastic that constitutes the battery tray is bent between the second inner wall 207 and the first bottom 303. The first bottom 303 and the second inner wall 207 are continuous, and the first bottom 303 and the second inner wall 207 are integrally formed without a seam. By using fiber-reinforced plastic, seamless integral molding can be easily performed. The first inner wall 206 and the second inner wall 207 are formed by bending the fiber-reinforced plastic that forms the battery tray.

[0060] [Battery Tray: Internal Partition Wall] The first inner wall 206 and the second inner wall 207 form the internal partition wall 107 shown in FIG. 1 that partitions the inside of the battery tray 105. There may be two or more such internal partition walls 107. In FIGS. 1 and 2, the internal partition wall 107 is formed in the Y-axis direction, and a total of four internal partition walls 107 extend. The X-axis in FIGS. 1 and 2 preferably indicates the axle direction (the traveling direction of the vehicle), and the Y-axis indicates the vehicle width direction.

[0061] [Battery Tray: Stud Bolt Base] The battery tray 105 may include a stud bolt base 407 that is connected to both the first inner wall 206 and the second inner wall 207 and is raised from the first bottom 303. The stud bolt base 407 is composed of fiber-reinforced plastic integrally formed with the first bottom 303, the peripheral wall 205, the first inner wall 206, the second inner wall 207, and the second bottom 301. The stud bolt base 407 is preferably connected to both the first inner wall 206 and the second inner wall 207 and is raised from the first bottom 303. The first inner wall 206 and the second inner wall 207 may be connected to each other via the stud bolt base 407.

[0062] That is, the battery tray 105 includes a flange 402, a first bottom portion 303, a peripheral wall 205 erected on the outer periphery of the first bottom portion 303, a first inner wall 206 connected to the first bottom portion 303, a second inner wall 207 connected to the first bottom portion 303, and a stud bolt base 407 connected to both the first inner wall 206 and the second inner wall 207 and rising from the first bottom portion 303.

[0063] When the stud bolt base 407 is provided on the battery tray 105, there is no need to provide the stud bolt base 407 as a separate component. Since the battery tray 105, which is a component of the battery box 101, is made of integrally molded fiber-reinforced plastic, the stud bolt base 407 is provided as soon as the molding of the fiber-reinforced plastic is completed.

[0064] In the battery tray described in Patent Document 1, since it is necessary to provide large battery brackets on both sides of the battery tray, the battery tray becomes large. When such large battery brackets are provided, in order to mount the same amount and number of batteries, it is necessary to increase the width of the vehicle itself (the degree of freedom in vehicle design decreases). Since the stud bolt bases are provided at a plurality of locations on the upper part of the internal partition wall, the degree of freedom in vehicle design is improved.

[0065] [Battery Tray: Second Bottom] Further, the first inner wall 206 and the second inner wall 207 are connected via the second bottom portion 301, and it is preferable that the second bottom portion 301 is raised by the first inner wall 206 and the second inner wall 207. That is, the first inner wall 206 and the second inner wall 207 form an internal partition wall 107, and the second bottom portion 301 is the bottom of the upper part of the internal partition wall 107.

[0066] FIG. 3 is a cross-sectional view taken along line 202-202 of FIG. 2, and the second bottom portion 301 is depicted at the lower part of the upper part of the internal partition wall 107 formed by the first inner wall 206 and the second inner wall 207. FIG. 3 is a cross-sectional view of a position where it is not necessary to provide the stud bolt insertion hole 412, and the stud bolt base 407 is not shown. The opposite surface of the second bottom 301 may be covered with a metal cover 304 to improve rigidity.

[0067] [Battery tray: Height of the second bottom] It is preferable that the height h1 from the first bottom to the flange and the height h3 from the first bottom to the upper surface of the second bottom satisfy the relationship of h1×0.3 < h3 < h1×2.0. The heights h1 and h3 are shown in FIG. 3. When the second bottom is a curved surface or the like, the length at which h3 is maximum is measured.

[0068] When h1×0.3 < h3, the height of the internal partition wall becomes high, so the batteries (103, 410) can be stably held. Regarding the lower limit value of h3, it is more preferable that h1×0.5 < h3, even more preferable that h1×0.6 < h3, and even more preferably that h1×0.7 < h3.

[0069] Regarding the upper limit value of h3, it is more preferable that h3 < h1×1.8, even more preferable that h3 < h1×1.5, even more preferably that h3 < h1×1.2, and most preferably that h3 < h1×1.0.

[0070] [Battery tray: Relationship between the second bottom and the recess] The components of the battery box 101 of the present invention include a plurality of recesses 208 to form a space 313. In other words, the recess forms a space region 313 surrounded by the first inner wall 206, the second inner wall 207, and the second bottom 301 (or the stud bolt base 407).

[0071] [Battery tray: Integral molding] The first bottom 303, the peripheral wall 205, the first inner wall 206, the second inner wall 207, and the second bottom 301 are made of integrally formed fiber-reinforced plastic. In a preferred embodiment, the stud bolt base 407 for fixing the battery can also be integrally formed. Further, the flange 402, the first bottom 303, the peripheral wall 205, the first inner wall 206, the second inner wall 207, and the stud bolt base 407 are made of integrally formed fiber-reinforced plastic.

[0072] [Battery Tray: Cross Member] In the vehicle structure of the present invention, as shown in FIGS. 7B and 7C, it is preferable that a cross member 701 extending in the vehicle width direction is inserted into the battery tray 105. In this case, the battery tray 105 (1) includes a first bottom 303, a peripheral wall 205 erected on the outer periphery of the first bottom 303, a first inner wall 206 connected to the first bottom 303, a second inner wall 207 connected to the first bottom, and a second bottom 301 connected to both the first inner wall 206 and the second inner wall 207 and raised from the first bottom.

[0073] The first bottom 303, the peripheral wall 205, the first inner wall 206, the second inner wall 207, and the second bottom 301 are made of integrally formed fiber-reinforced plastic. A recess extending in the vehicle width direction is formed by the first inner wall 206, the second inner wall portion 207, and the second bottom 301. The cross member is inserted into at least one location of the recess.

[0074] [Cross Member: Arrangement] Specifically, a recess 208 extending in the vehicle width direction is formed by the first inner wall 206, the second inner wall portion 207, and the second bottom 301, and it is preferable that the cross member 701 is inserted into at least one location of the recess 208. The recess 208 forms a space region 313 surrounded by the first inner wall 206, the second inner wall 206, and the second bottom 301.

[0075] After the cross member 701 is inserted into the recess 208, it is preferable to provide a space 703 between the cross member 701 and the second bottom portion 301. By providing the space 703, the collision sound between the cross member 701 and the battery tray 105 can be avoided.

[0076] Preferably, there are a plurality of cross members 701, and it is more preferable that the cross members 701 are inserted into two or more positions of the recess 208 extending in the vehicle width direction formed by the first inner wall 206, the second inner wall 207, and the second bottom portion 301. It is more preferable that the cross members are inserted into all the recesses 208. The cross member 701 preferably extends in the vehicle width direction of the battery tray 105, and as shown in FIG. 2, it may extend from one end to the other end in the vehicle width direction of the battery tray 105.

[0077] [Cross member: Shape] The shape of the cross member 701 is not particularly limited, and when the cross section of the cross member 701 is viewed from the vehicle width direction (the Y-axis direction in FIG. 2), the cross section may be T-shaped, L-shaped, or a combination thereof. The cross member 701 is bent convexly along the recess 208 formed by the first inner wall 206, the second inner wall 207, and the second bottom portion 301 so as to extend in the vehicle width direction. In other words, when the vehicle structure is viewed in cross section from the vehicle side direction, it is preferable that the cross member is bent so as to be convex upward and inserted into the recess 208. FIGS. 7B and 7C show the bent cross member 701. The cross member 701 is formed in a convex shape along the recess 208 by pressing and bending a flat metal plate. Here, "along the recess" means that it does not need to completely follow the recess and may substantially follow it.

[0078] When the cross-section of the vehicle structure is viewed from the vehicle width direction, it is preferable that a closed cross-section structure 703 as shown in FIGS. 7B and 7C is formed by the first inner wall 206, the second inner wall 207, the second bottom portion 301, and the cross member 701. In order to avoid the collision sound between the cross member 701 and the second bottom portion 301, the height of the protruding shape of the cross member 701 is preferably set such that the cross member 701 does not contact the second bottom portion 301.

[0079] [Cross member: Fitting] The cross member 701 preferably extends in the vehicle width direction and is fitted into the recess 208. In this case, the cross member 701 is preferably convex as shown in FIGS. 7B and 7C. That is, the protruding portion of the cross member 701 is preferably fitted into the recess 208 extending in the vehicle width direction formed by the first inner wall 206, the second inner wall 207, and the second bottom portion 301.

[0080] [Cross member: Joining] The cross member 701 is preferably joined to the first bottom portion 303 and may be adhered to the first bottom portion 303 with an adhesive. In the case of adhesion, it is not necessary to form holes in the battery tray 105, and the airtightness is improved as compared with the case of fastening.

[0081] [Cross member: Material] The cross member 701 is preferably made of metal or a fiber-reinforced composite material. When using a fiber-reinforced composite material reinforced with continuous fibers, the fibers are preferably oriented in the vehicle width direction (Y-axis direction in FIG. 2). The metal may be an alloy.

[0082] [Cross member: Thickness] The thickness of the cross member 701 is preferably 0.5 mm or more and 6.0 mm or less, more preferably 1.0 mm or more and 5.0 mm or less, and even more preferably 1.0 mm or more and 4.0 mm or less.

[0083] [Effect of cross member arrangement] The battery tray 105 has a recess 208, and the recess 208 forms a space region 313 surrounded by a first inner wall 206, a second inner wall 207, and a second bottom 301. By providing the recess 208, the battery tray 105 becomes more flexible in the vertical direction. More specifically, the vertical bending is the bending in the direction of arrow 901 in FIG. 9 and is the bending of the end portions of the battery tray 105 in the vehicle front-rear direction.

[0084] The cross member 701 is inserted into the recess 208 of the battery tray 105, and by joining the first bottom 303 to the cross member 701, the vertical deflection (in the direction of arrow 901 in FIG. 9) due to vibration is suppressed. By extending the cross member 701 in the vehicle width direction and fitting it into the recess 208 for joining, the deflection of the cross member 701 can be further suppressed.

[0085] [Ribs in the recess of the battery tray] In the vehicle structure of the present invention, as shown in FIG. 7C, it is preferable that ribs 702 integrally formed with the battery tray 105 are provided at at least one location in the recess 208. In other words, the ribs 702 are preferably provided in at least one of the recesses 208 extending in the vehicle width direction formed by the first inner wall 206, the second inner wall 207, and the second bottom 301. It is more preferable that a plurality of ribs 702 are intermittently provided in the extending direction in the extending recess 208. FIG. 7C shows a portion where the ribs 702 are present in the recess of the battery tray 105, and FIG. 7B shows a portion where the ribs 702 are not present in the recess of the battery tray 105.

[0086] The thickness of the ribs 702 in the recess 208 of the battery tray 105 is preferably 1 mm or more and 4 mm or less, and more preferably 2.5 mm or more and 3 mm or less. The height of the ribs 702 is preferably 10 mm or more and 30 mm or less. The thickness of the ribs 702 is the thickness in the Y-axis direction in FIGS. 7A to 7C, and the height of the ribs 702 is the height in the Z-axis direction in FIGS. 7A to 7C.

[0087] By providing the rib 702 in the recess 208 of the battery tray 105, it is possible to suppress the deflection in the vertical direction (the direction of the arrow 901 in FIG. 9) due to vibration.

[0088] [Natural frequency of the first mode of the battery tray] The natural frequency of the first mode of the battery tray 105 is preferably 25 Hz or more. Generally, since the natural frequency of the vehicle body is 25 Hz or less, it is preferable to design the battery tray 105 so as not to resonate with the vehicle body. More preferably, the natural frequency of the first mode of the battery tray 105 is 30 Hz or more, even more preferably 35 Hz or more, and even more preferably 40 Hz or more.

[0089] More specifically, by providing the rib 702 integrally formed with the battery tray 105 at at least one location of the recess 208, it is preferable that the natural frequency of the first mode of the battery tray 105 becomes 25 Hz or more. Since the battery tray 105 has the recess 208, it becomes easy to make the natural frequency of the first mode 25 Hz or more. Alternatively, by further providing the rib 702 in the recess 208, the natural frequency of the first mode of the battery tray 105 can be more easily made 25 Hz or more.

[0090] It is preferable that the rib 702 and the cross member 701 do not contact each other and there is a gap between the two. Since the rib 702 and the cross member 701 do not contact each other, it is possible to avoid the knocking sound between the rib 702 and the cross member 701.

[0091] If only anti-vibration is considered, there is no problem even without the cross member 701. Therefore, the following invention will be described as the battery tray 105 with the cross member 701 removed from the vehicle structure of the present invention.

[0092] [Battery tray with rib] The battery tray is the battery tray 105 disposed at the lower center of the vehicle body. (1) The battery tray 105 includes a first bottom 303, a peripheral wall 205 erected on the outer periphery of the first bottom 303, a first inner wall 206 connected to the first bottom 303, a second inner wall 207 connected to the first bottom 303, a second bottom 301 connected to both the first inner wall 206 and the second inner wall 207 and raised from the first bottom 303. (2) The first bottom 303, the peripheral wall 205, the first inner wall 206, the second inner wall 207, and the second bottom 301 are made of integrally molded fiber-reinforced plastic. (3) A recess 208 extending in the vehicle width direction is formed by the first inner wall 206, the second inner wall portion 207, and the second bottom 301. (4) At least one rib integrally molded with the battery tray 105 is provided at at least one location of the recess 208.

[0093] [Joint between cross member and structural member A] The cross member 701 is preferably joined to the structural member A (108), and more preferably the joint is welding. By joining the cross member 701 and the structural member A (108), when collision energy is input to the side of the vehicle, not only the structural member A (108) but also the cross member 701 can contribute to the absorption of the collision energy. Since the structural member A (108) is located outside the vehicle width direction from the battery cover 102 and the battery tray 105, the structural member A (108) is provided on both sides of the vehicle. By joining the structural member to the cross member 701, not only the structural member A (108) on the side receiving the impact but also the structural member A (108) on the side opposite to the side receiving the impact can contribute to the absorption of the collision energy.

[0094] [Battery tray: Angle] The angle formed by the first bottom 303 and the first inner wall 206 is indicated by α in FIG. 4. The angle formed by the first bottom 303 and the second inner wall 207 is indicated by β in FIG. 4. The angle α formed by the first bottom 303 and the first inner wall 206, and the angle β formed by the first bottom 303 and the second inner wall 207 are preferably not less than 90 degrees and not more than 135 degrees. When the angles α and β are not less than 90 degrees, it becomes easier to take out the battery tray from the molding die during molding. On the other hand, if the angles α and β are not more than 135 degrees, even if the shape of the battery 103 is a rectangular parallelepiped or a cube, it becomes easier to match the first inner wall 206 and the second inner wall 207 to the shape of the battery 103.

[0095] That is, if the angle α formed by the first bottom 303 and the first inner wall 206, and the angle β formed by the first bottom 303 and the second inner wall 207 are not less than 90 degrees and not more than 135 degrees, the size of the battery 103 can be increased with respect to the battery tray 105 per unit volume.

[0096] The angle α formed by the first bottom 303 and the first inner wall 206, and the angle β formed by the first bottom 303 and the second inner wall 207 are more preferably not less than 90 degrees and not more than 120 degrees, and even more preferably not less than 90 degrees and not more than 100 degrees.

[0097] In order to measure the angle α formed by the first bottom 303 and the first inner wall 206, and the angle β formed by the first bottom 303 and the second inner wall 207, it is sufficient to observe the cross section of the battery tray 105. The direction of cross-section observation is preferably a direction perpendicular to the first inner wall 206 or the second inner wall 207 (for example, cross-section observation in FIG. 4).

[0098] In cross-section observation, when the first bottom 303, the first inner wall 206, or the second inner wall 207 has a curved shape, a tangent is drawn to the curve, the angle with the tangent is measured, and the average of the maximum angle and the minimum angle is calculated to obtain the angle α or the angle β.

[0099] [Battery Tray: Stud Bolt and Stud Bolt Base] The battery tray 105 of the present invention preferably includes a stud bolt 409 for attaching a battery bracket on a stud bolt base 407. The first inner wall 206 and the second inner wall 207 are connected via the stud bolt base 407. In other words, the stud bolt base 407 is preferably provided at an upper position of the internal partition wall 208.

[0100] Also, the stud bolt base 407 includes a non-penetrating insertion hole 412, and the stud bolt 409 is inserted into the insertion hole 412. The stud bolt 409 is a bolt having threaded portions formed at both ends, and one end of the stud bolt 409 is screwed into the insertion hole of the stud bolt base 407. On the opposite side, a battery bracket 411 for fixing the battery is fastened. The shape of the stud bolt 409 is not particularly limited.

[0101] The thickness t1 of the stud bolt base 407 shown in FIG. 5A and the thickness t2 of the second bottom 301 shown in FIG. 3 preferably satisfy t2 < t1. In other words, it is preferable that the thickness of the top 201 of the internal partition wall 208 formed by the first inner wall 206 and the second inner wall 207 contributes to forming an uneven thickness structure in the Y-axis direction (vehicle width direction). The top 201 is preferably a repeating structure of the stud bolt base 407 and the second bottom 301. The thickness t2 of the second bottom is designed to be smaller than the thickness t1 (also called the wall thickness) of the stud bolt base, thereby reducing the weight of the battery tray 105. It is more preferable to satisfy t2 × 0.8 < t1, and it is even more preferable to satisfy t2 × 0.5 < t1. The flange 402, the first bottom 303, the peripheral wall 205, the first inner wall 206, the second inner wall 207, the stud bolt base 407, and the second bottom 301 are made of integrally molded fiber-reinforced plastic.

[0102] [Battery Tray: Through-Hole for Fixing Battery] In the case of a conventional battery tray, in order to fasten the battery to the battery tray, it was necessary to provide through holes in the battery tray and fix the battery bracket to the battery tray.

[0103] In a preferred embodiment of the present invention, the stud bolt base 407 is made of a fiber-reinforced plastic integrally formed with the battery tray 105 and has an uneven structure with a thickness. That is, the first inner wall 206, the second inner wall 207, the first bottom 303, and the stud bolt base 407 may not be provided with through holes for fixing the battery 103. By not providing such through holes, the sealing performance of the battery box 101 can be improved, the humidity inside the battery box 101 can be stabilized, and the life of the battery can be extended. Further, it is preferable that the peripheral wall 205 is not provided with a through hole for fixing the battery 103.

[0104] [Battery Tray: Height of Stud Bolt Base] It is preferable that the height h1 from the first bottom 303 to the flange 402 and the height h2 from the first bottom 303 to the upper surface of the stud bolt base 407 satisfy h1×0.3 < h2 < h1×2.0.

[0105] Since the first bottom 303 has a thickness, the height h1 is measured with reference to the vertical center of the first bottom 303. When the first bottom 303 is wavy or has a curved surface, the length at which h2 is maximum is measured.

[0106] The heights h1 and h2 are shown in FIG. 4. If h1×0.3 < h2, since the position of the stud bolt base 407 is higher than that of the first bottom 303, the position of the stud bolt 409 for attaching the battery bracket 411 can be raised. As a result, the fixing position of the battery bracket 411 for fixing the battery becomes higher, and the length of the battery bracket 411 can be shortened. Since the battery bracket 411 is generally made of a metal such as aluminum, shortening the length of the battery bracket 411 can contribute to weight reduction.

[0107] Regarding the lower limit value of h2, it is more preferable that h1×0.5 < h2, still more preferable that h1×0.6 < h2, and even more preferable that h1×0.7 < h2. Regarding the upper limit value of h2, it is more preferable that h2 < h1×1.8, still more preferable that h2 < h1×1.5, even more preferable that h2 < h1×1.2, and most preferable that h2 < h1×1.0.

[0108] When h1×0.3 < h2 < h1×2.0 is satisfied, as shown in FIG. 4, the space region 313 surrounded by the first inner wall 206, the second inner wall 207, and the stud bolt base 407 becomes larger. When the space region 313 is large, even if the stud bolt base 407 is provided, the cross member 701 can be easily inserted.

[0109] The relationship between the height h2 from the first bottom 303 to the upper surface of the stud bolt base 407 and the height h3 from the first bottom 303 to the upper surface of the second bottom 301 is preferably h2×0.8 < h3 < h1×1.2, more preferably h2×0.9 < h3 < h1×1.1, and still more preferably h2 = h3.

[0110] [Battery tray: Ribs and bosses for fixing the battery] Preferably, ribs or bosses for fixing the battery 103 are provided on the upper surface of the first bottom portion 303 of the battery tray 105. The upper surface of the first bottom portion is the surface on which the battery of the battery tray 105 is placed. The lower surface is the surface on the opposite side of the upper surface. The ribs or bosses preferably fix not only the battery but also the wiring and the cooling mechanism 104. Here, "fixing" means suppressing the movement of the battery and does not mean complete fixing.

[0111] The relationship between the height hr of the rib and the height hb of the battery is preferably hb×0.3 < hr, and more preferably hb×0.5 < hr. Specifically, the height hr of the rib is preferably 20 to 70 mm, more preferably 30 to 60 mm, and even more preferably 40 to 50 mm. Within this range, the rigidity of the battery tray 105 can also be improved. Also, the ribs or bosses for fixing the battery are preferably integrally formed of a fiber-reinforced plastic. By providing the ribs or bosses by integral molding with the fiber-reinforced plastic, the fixing of the battery can be easily strengthened.

[0112] [Battery Tray: Shapes of the First Inner Wall and the Second Inner Wall] 1. Shape along the battery shape Preferably, at least one of the first inner wall 206 and the second inner wall 207 has a shape along the battery shape. More preferably, the first inner wall 206 and the second inner wall 207 have a shape along the battery shape. That is, the internal partition wall 208 more preferably has a shape along the battery shape.

[0113] "Shape along the battery shape" means that the shape of the first inner wall 206 or the second inner wall 207 is designed along the shape of the battery. For example, when the battery 103 is a cube or a rectangular parallelepiped, the first inner wall 206 or the second inner wall 207 is a straight wall.

[0114] For one battery, a first inner wall and a second inner wall may be provided along the shape of the battery (along the outer periphery of the battery). By providing an internal partition wall (formed by the first inner wall and the second inner wall) for each battery, it is preferable because even if a problem such as combustion occurs in one battery, it will not affect other batteries. In FIG. 2, the first inner wall (206) and the second inner wall (207) are shown only in the vehicle width direction (the Y-axis direction in FIG. 2), but they may extend in the traveling direction (the X-axis direction in FIG. 2).

[0115] 2. Mounting to the lower part of the vehicle body The battery tray 105 in the present invention is preferably attached to the lower part of the vehicle body of an electric vehicle and has a first inner wall 206 and a second inner wall 207 along the vehicle width direction. Thereby, the cross member can be easily installed in the vehicle width direction.

[0116] Here, the "vehicle width direction" is, for example, the Y direction in FIG. 1, which is the vehicle width direction. Also, the left-right direction of the vehicle body is also referred to as the vehicle width direction. For example, in FIG. 1, the internal partition wall 107 which is the first inner wall and the second inner wall extends in the vehicle width direction.

[0117] [Battery tray: Dispersion of discontinuous fibers in the boundary region] In the boundary regions between the first bottom 303 and the first inner wall 206, between the first bottom 303 and the second inner wall 207, and between the first bottom 303 and the peripheral wall 205, it is preferable that discontinuous fibers are continuously dispersed.

[0118] Since the first bottom 303, the peripheral wall 205, the first inner wall 206, and the second inner wall 207 are formed of integrally molded fiber-reinforced plastic, discontinuous fibers can be easily and continuously dispersed in the boundary regions.

[0119] "Reinforcing fibers are continuously dispersed in the boundary region" means that the reinforcing fibers only need to be continuously dispersed in at least a part of the boundary region, and it is not necessary for the reinforcing fibers to be continuously dispersed in the entire boundary region. When the reinforcing fibers are continuously dispersed in the in-plane direction in the boundary region, the mechanical properties of the boundary region are improved compared to the prior art.

[0120] When the components of the battery box 101 are not integrally formed and the partition wall corresponding to the first inner wall 206 or the second inner wall 207 is attached as a separate part, it is necessary to fasten the partition wall to the first bottom 303. However, when the internal partition wall is attached as a separate part without being integrally formed, the fastening force to the first bottom 303 inevitably decreases, and the fastening force becomes unstable.

[0121] [Battery tray: Curvature radius of the inner corner] In the boundary region between the first bottom 303 and the peripheral wall 205, it is preferable to form an inner corner with a curvature radius of 1 mm or more and 10 mm or less. The curvature radius is more preferably 1 mm or more and 7 mm or less, and even more preferably 2 mm or more and 4 mm or less. The inner corner in the boundary region between the first bottom 303 and the peripheral wall 205 is indicated by R501 in FIGS. 5A and 5C.

[0122] Also, in the boundary region between the first bottom 303 and the first inner wall 206, it is preferable to form an inner corner with a curvature radius of 1 mm or more and 10 mm or less. The inner corner in the boundary region between the first bottom 303 and the first inner wall 206 is indicated by R520 in FIGS. 5A and 5B. More preferably, it is 1 mm or more and 7 mm or less, and even more preferably 2 mm or more and 4 mm or less.

[0123] Also, in the boundary region between the first bottom 303 and the second inner wall 207, it is preferable to form an inner corner with a curvature radius of 1 mm or more and 10 mm or less. The inner corner in the boundary region between the first bottom 303 and the second inner wall 207 is indicated by R530 in FIGS. 5A and 5B. The curvature radius is more preferably 1 mm or more and 7 mm or less, and even more preferably 2 mm or more and 4 mm or less.

[0124] [Battery tray: Curvature radius of the outer corner] In the boundary region between the first bottom 303 and the peripheral wall 205, it is preferable to form an outer corner portion having a curvature radius of 2 mm or more and 11 mm or less. The curvature radius is more preferably 2 mm or more and 8 mm or less, and still more preferably 3 mm or more and 7 mm or less. The outer corner portion in the boundary region between the first bottom 303 and the peripheral wall 205 is indicated by R502 in FIG. 5C.

[0125] Also, in the boundary region between the first bottom 303 and the first inner wall 206, it is preferable to form an outer corner portion having a curvature radius of 2 mm or more and 11 mm or less. The outer corner portion in the boundary region between the first bottom 303 and the first inner wall 206 is indicated by R521 in FIG. 5B. The curvature radius is more preferably 2 mm or more and 8 mm or less, and still more preferably 3 mm or more and 7 mm or less.

[0126] Also, in the boundary region between the first bottom 303 and the second inner wall 207, it is preferable to form an outer corner portion having a curvature radius of 2 mm or more and 11 mm or less. The outer corner portion in the boundary region between the first bottom 303 and the second inner wall 207 is indicated by R531 in FIG. 5B. The curvature radius is more preferably 2 mm or more and 8 mm or less, and still more preferably 3 mm or more and 7 mm or less. The curvature radius of the outer corner portion is preferably larger than the curvature radius of the inner corner portion.

[0127] [Structural member A] With the increase in the mounting amount of automotive batteries, the battery box 101 has been growing in size year by year. The length of the battery box 101 in the vehicle width direction is often 70% or more of the width of the vehicle, and may be 80% or more. Therefore, when a large battery box 101 is mounted at the lower part of the vehicle, a larger load than before is input to the battery box 101 during a collision. For this reason, an energy absorption structure for protecting the battery itself is required.

[0128] The structural member A (108) is a member for ensuring rigidity and can also absorb energy during a collision. That is, the structural member A (108) is also an energy absorption member disposed on the outer side in the vehicle width direction of the peripheral wall of the battery tray 105, and absorbs collision energy from the vehicle width direction.

[0129] [Shape of Structural Member A] As shown in FIG. 10, the structural member A (108) has a first longitudinal wall 1001 and a second longitudinal wall 1002 located on the inner side in the vehicle width direction of the first longitudinal wall 1001, and the first longitudinal wall 1001 and the second longitudinal wall 1002 extend in the vehicle longitudinal direction.

[0130] It is preferable that the minimum thickness of the first longitudinal wall 1001 is smaller than the maximum thickness of the second longitudinal wall 1002. Since the minimum thickness of the first longitudinal wall 1001 is smaller than the maximum thickness of the second longitudinal wall 1002, when collision energy is applied to the side surface of the vehicle, the first longitudinal wall 1001 breaks to absorb energy, and the second longitudinal wall (inner wall) 1002 can protect the battery 103.

[0131] That is, the structural member A (108) has a first longitudinal wall 1001 and a second longitudinal wall 1002 located on the inner side in the vehicle width direction of the first longitudinal wall 1001, the first longitudinal wall 1001 and the second longitudinal wall 1002 extend in the vehicle longitudinal direction, and the strength of the first longitudinal wall 1001 is lower than the strength of the second longitudinal wall 1002.

[0132] The relationship between the maximum thickness t2max of the second longitudinal wall and the minimum thickness t1min of the first longitudinal wall is t2max × 0.9 > t1min, t2max × 0.8 > t1min.

[0133] [Height of Structural Member A] Hereinafter, the vertical position (height) of the structural member A will be described. The lowermost part of the structural member A (108) is preferably located at a position lower than the lowermost part of the battery tray 105. More preferably, the lowermost part of the structural member A (108) is below the first bottom portion 303 of the battery tray 105, and the uppermost part of the structural member A (108) is above the first bottom portion 303 of the battery tray 105.

[0134] When viewed from the vehicle width direction, the upper end of the first vertical wall 1001 of the structural member A (108) is preferably located above the first bottom portion 303 of the battery tray 105, and the lower end of the first vertical wall 1001 of the structural member A (108) is preferably located below the first bottom portion 303 of the battery tray 105.

[0135] When viewed from the vehicle width direction, the upper end of the second vertical wall 1002 of the structural member A (108) is preferably located above the first bottom portion 303 of the battery tray 105, and the lower end of the second vertical wall 1002 of the structural member A (108) is preferably located below the first bottom portion 303 of the battery tray 105.

[0136] When viewed from the vehicle width direction, if the first bottom portion 303 of the battery tray 105 is covered by the structural member A (108), the first bottom portion 303 of the battery tray 105 can be protected by the structural member A (108) during a collision.

[0137] Also, by adjusting the vertical position (height) of the structural member A (108), when a protective wall 1401 described later is provided, the battery tray 105 can be protected from an impact received from below.

[0138] [Structural member: Joint tightening] The structural member A (108) is located on the outer side in the vehicle width direction of the battery tray 105 and the battery cover 102, and is jointly tightened with the battery tray 105 and the battery cover 102. By jointly tightening in this way, when an impact is applied to the side surface of the vehicle, the structural rigidity of the battery tray 105 can be utilized in addition to the vehicle body.

[0139] As shown in FIG. 11, the structural member A (108) is preferably fastened together with the battery tray 105 and the battery cover 102 by the stepped bolt 1101. The stepped bolt 1101 refers to a bolt in which the diameter of the unthreaded cylindrical portion is larger than the nominal diameter of the thread. When the battery tray 105 or the battery cover 102 is a part formed by sheet molding compound, the thickness of the battery tray 105 or the battery cover 102 decreases (becomes thinner) over time due to creep phenomenon or the like. However, by using the stepped bolt 1101, the fastening between the battery cover 102, the battery tray 105, and the structural member A (108) (or the structural members B and C described later) can be maintained more stably.

[0140] When using the stepped bolt 1101, as shown in FIG. 10, it is preferable to stack and fasten the battery cover 102, the battery tray 105, and the structural member A (108) in this order, or to stack and fasten the structural member A (108), the battery cover 102, and the battery tray 105 in this order. By stacking in this order, even if the battery tray 105 and the battery cover 102 formed of sheet molding compound become thinner (the phenomenon of thickness reduction due to creep phenomenon or the like), the fastening can be stably maintained.

[0141] [Structural members B and C] As a structural member for absorbing collision energy, it is preferable to further include a structural member B (1302) provided along the outer side in the vehicle body front-rear direction of the peripheral wall. Further, it is preferable to further include a structural member C (1303) at the corner of the peripheral wall. In addition, since the structural members for absorbing collision energy are provided not only on the outer side in the vehicle width direction but also on the entire outer side of the peripheral wall, there is an effect that it can cope with impact inputs from any direction.

[0142] The structural members B1302 and C1303 are also preferably arranged outside the battery tray 105 and the battery cover 102 and fastened together with the battery tray 105 and the battery cover 102.

[0143] [Protective wall] The vehicle structure may include a protective wall under the battery tray. 1. Details are as follows. A vehicle structure including a battery tray and a protective wall provided below the battery tray. The battery tray and the protective wall are formed of fiber-reinforced plastic. The protective wall is fastened to at least one position of the battery tray by a fastening rod. Insertion holes for fastening are integrally formed in the battery tray. An example of the protective wall is shown at 1401 in FIG. 14. The fastening rod is shown at 1402 in FIG. 14, and the insertion hole is shown at 1403 in FIG. 14. The protective wall 1401 under the battery tray 105 is preferably connected to the structural member A (108). The protective wall 1401 can protect the battery tray 105 from impacts received from below.

[0144] 2. Insertion hole An insertion base (1404 in FIG. 14) protruding from the battery tray toward the protective wall is provided, and the insertion hole is preferably arranged inside the insertion base.

[0145] 3. Shock-absorbing member It is preferable to arrange a shock-absorbing member (1405 in FIG. 14) between the battery tray and the protective wall. Further, the shock-absorbing member more preferably has a honeycomb structure. By providing such a shock-absorbing member, the impact resistance from the lower part of the vehicle is improved.

[0146] 4. Aerodynamic plate for adjusting air flow The protective wall is preferably a fiber-reinforced plastic provided with an aerodynamic plate for regulating air flow by integral molding, and an aerodynamic plate for regulating air flow may be provided below the protective wall. By providing an aerodynamic plate for regulating air flow, air resistance is reduced and the running stability of the vehicle is improved.

[0147] 5. Electromagnetic wave shielding layer It is preferable to provide an electromagnetic wave shielding layer between the protective wall and the battery tray. More specifically, the electromagnetic wave shielding layer can be provided on the upper surface of the protective wall. In this case, the shock absorption member is preferably disposed above the electromagnetic wave shielding layer.

[0148] 6. Material for the protective wall 6.1 The protective wall may be a fiber-reinforced plastic obtained by molding a sheet molding compound containing reinforcing fibers and a thermosetting resin. 6.2 The protective wall may be a fiber-reinforced plastic obtained by molding a composite material containing reinforcing fibers and a thermoplastic resin. 7. Thickness of the protective wall The thickness of the protective wall is preferably 1 mm or more, more preferably 3 mm or more, and even more preferably 5 mm or more.

[0149] [Collision test results] The vehicle structure shown in FIG. 7A was created using glass fiber-reinforced plastic (SMC) for the battery cover and the battery tray, and steel for structural member A. The vehicle structure was tested based on the GB standard 38031-2020 8.2.4 collision test. The maximum reaction force in the X direction (vehicle width direction) in FIG. 7A was 230 kN, exceeding the reference value of 100 kN.

Explanation of symbols

[0150] 101: Battery box 102: Battery cover 103: Battery 104: Temperature control system (cooling mechanism) 105: Battery tray 106: Reinforcing frame 107: Internal partition wall formed by the first inner wall and the second inner wall 108: Structural member A (member capable of absorbing energy) 201: Upper part of the internal partition wall 205: Peripheral wall 206: First inner wall 207: Second inner wall 208: Recess extending in the vehicle width direction 301: Second bottom 302: Cooling mechanism 303: First bottom 304: Metal cover 313: Space region surrounded by the first inner wall, the second inner wall, and the second bottom (or stud bolt base) 402: Flange 407: Stud bolt base 408: Upper surface of the stud bolt base 409: Stud bolt 411: Battery bracket 412: Insertion hole α: Angle formed by the first bottom and the first inner wall β: Angle formed by the first bottom and the second inner wall h1: Height from the first bottom to the flange h2: Height from the first bottom to the upper surface of the stud bolt base h3: Height from the first bottom to the second bottom R501: Inner corner in the boundary region between the first bottom and the peripheral wall R502: Outer corner in the boundary region between the first bottom and the peripheral wall R520: Inner corner in the boundary region between the first bottom and the first inner wall R521: Outer corner in the boundary region between the first bottom and the first inner wall R530: Inner corner in the boundary region between the first bottom and the second inner wall R531: Outer corner in the boundary region between the first bottom and the second inner wall 701: Cross member 702: Rib 703: Space between the cross member and the second bottom formed when the cross member is inserted into the recess 801: Battery cover 802: Rib 1001: First vertical wall 1002: Second vertical wall 1101: Step bolt 1201: Fixing point between the structural member A and the vehicle body 1302: Structural member B 1303: Structural member C 1401: Protection wall 1402: Fastening rod 1403: Insertion hole 1404: Insertion table 1405: Impact absorption member

Claims

1. A vehicle structure disposed at the lower center of the vehicle body, comprising a battery cover, a battery tray, and a structural member for absorbing impact energy. The battery cover and the battery tray are each made of integrally molded fiber-reinforced plastic. The structural member is located on at least one outer side in the vehicle width direction of the battery cover and the battery tray. The structural member is fastened together with the battery cover and the battery tray. The battery tray has a first bottom, a first inner wall connected to the first bottom, a second inner wall connected to the first bottom, and a second bottom connected to both the first inner wall and the second inner wall and standing upright from the first bottom. A recess extending in the vehicle width direction is formed by the first inner wall, the second inner wall, and the second bottom. A cross member is inserted into at least one location of the recess. The cross member is joined to the structural member. A vehicle structure.

2. The vehicle structure according to claim 1, wherein the structural member is fastened together with the battery tray and the battery cover by a stepped bolt.

3. The vehicle structure according to claim 2, wherein the battery cover, the battery tray, and the structural member are stacked and fastened together in this order.

4. The vehicle structure according to claim 2, wherein the structural member, the battery cover, and the battery tray are stacked and fastened together in this order.

5. The structural member has a first vertical wall and a second vertical wall located on the inner side in the vehicle width direction than the first vertical wall. The first vertical wall and the second vertical wall extend in the longitudinal direction of the vehicle body. The vehicle structure according to any one of claims 1 to 4, wherein the minimum thickness of the first vertical wall is smaller than the maximum thickness of the second vertical wall.

6. The vehicle structure according to any one of claims 1 to 5, wherein the battery cover and the battery tray are made of integrally molded fiber-reinforced plastic using sheet molding compound.

7. (1) The battery tray further has a peripheral wall standing upright on the outer periphery of the first bottom. (2) The first bottom, the peripheral wall, the first inner wall, the second inner wall, and the second bottom are made of integrally molded fiber-reinforced plastic. The vehicle structure according to any one of claims 1 to 6.

8. The angle formed by the first bottom and the first inner wall, and the angle formed by the first bottom and the second inner wall are each 90 degrees or more and 135 degrees or less. The vehicle structure according to claim 7.

9. In the boundary region between the first bottom and the first inner wall, the boundary region between the first bottom and the second inner wall, and the boundary region between the first bottom and the peripheral wall, discontinuous fibers are continuously dispersed. The vehicle structure according to claim 7 or 8.

10. The battery cover has ribs, and the natural frequency of the primary mode is 25 Hz or more. The vehicle structure according to any one of claims 1 to 9.

11. The specific heat of the fiber-reinforced plastic is 0.5 J / kg·°C or more and 2.0 J / kg·°C or less, and the minimum thickness is 1 to 5 mm. The vehicle structure according to claim 1.

12. A battery-mounted vehicle body having the vehicle structure according to any one of claims 1 to 11, fixed to the vehicle body, wherein the relationship between the number of fixing points n1 between the structural member and the vehicle body and the number of fixing points n2 between the battery cover and the vehicle body satisfies n1 > n2. A battery-mounted vehicle body.

13. The lowermost part of the structural member is located at a position lower than the lowermost part of the battery tray. The vehicle structure according to any one of claims 1 to 12.

14. The upper end of the first vertical wall of the structural member is above the first bottom of the battery tray, The lower end of the first vertical wall of the structural member is below the first bottom of the battery tray. The vehicle structure according to claim 5.

15. The upper end of the second vertical wall of the structural member is above the first bottom of the battery tray, The lower end of the second vertical wall of the structural member is below the first bottom of the battery tray. The vehicle structure according to claim 5.

16. The battery tray further includes a protective wall below it, The protective wall is connected to the structural member. The vehicle structure according to claim 13.

17. The structural member includes a first vertical wall and a second vertical wall located inside the first vertical wall in the vehicle width direction, The first vertical wall and the second vertical wall extend in the longitudinal direction of the vehicle body The strength of the first vertical wall is lower than the strength of the second vertical wall. The vehicle structure according to any one of claims 1 to 5.

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