Battery case

Abstract

This battery case offers advantages in protecting the battery pack without sacrificing space in the vehicle's interior. [Solution] Multiple pairs of inclined surfaces 24 and multiple lower surfaces 26 connecting the pairs of inclined surfaces 24 are formed on the battery case 12, creating multiple protrusions 30 that are spaced apart in the vehicle's longitudinal direction and extend in the vehicle's width direction. Therefore, when an object falling from the road surface collides with a protrusion 30, the load applied to the lower surface 26 of the protrusion 30 is transmitted to the upper surface 28 via the pairs of inclined surfaces 24. Thus, the load is distributed by the pairs of inclined surfaces 24 into a vertical load and a horizontal load (vehicle longitudinal direction) and transmitted to the battery case 12.

Description

Technical Field

[0001] The present invention relates to a battery case.

Background Art

[0002] Electric vehicles such as electric vehicles and hybrid vehicles that use a motor as a drive source include a battery pack that supplies electric power to the motor. The battery pack includes a plurality of battery modules, an electrical component section for controlling these battery modules, and a battery case that accommodates these battery modules and the electrical component section, and is disposed below a floor panel of the vehicle. The bottom surface of the case is covered with an under cover, so that the battery pack is protected from falling objects such as stones on the road surface (see Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] By the way, when traveling on rough roads such as gravel roads, it is important from the perspective of protecting the battery pack to ensure as much ground clearance as possible for the battery pack and the battery case. On the other hand, increasing the ground clearance of the battery pack and the battery case restricts the space of the vehicle cabin in the vertical direction. Therefore, how to achieve both protection of the battery pack and securing of vehicle cabin space has become an issue. The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery case that is advantageous for protecting a battery pack by the battery case without sacrificing the space of the vehicle cabin. [Means for solving the problem]

[0005] To achieve the above objective, one embodiment of the present invention is a battery case that covers the bottom surface of a battery pack located at the bottom of a vehicle, wherein the battery case has a protruding portion that extends in the vehicle width direction and, when cut by a vertical plane passing through the vehicle longitudinal direction, has a shape composed of a pair of inclined surfaces that face each other in the vehicle longitudinal direction and are inclined in a direction that moves away from each other as it goes upward, and a bottom surface that connects the lower ends of the inclined surfaces, and the protruding portion is formed in multiples that are continuously spaced apart in the vehicle longitudinal direction via a top surface that connects the upper ends of the inclined surfaces. Furthermore, one embodiment of the present invention is characterized in that the battery case is arranged such that its upper surface, which is spaced apart from the front and rear of the vehicle, is attached to the bottom surface of the battery pack. Furthermore, one embodiment of the present invention is characterized in that the ends of the battery case located in the vehicle width direction, which are located in the central region in the longitudinal direction of the vehicle, are located further outward in the vehicle width direction than the ends of the battery pack in the vehicle width direction. Furthermore, one embodiment of the present invention is characterized in that the spacing between the multiple protruding portions in the longitudinal direction of the vehicle is smaller in the portion in front of the vehicle than in the center of the longitudinal direction of the vehicle. Furthermore, one embodiment of the present invention is characterized in that, in the front of the vehicle, the width of the protruding portion along the vehicle's longitudinal direction is small, and in the center of the vehicle's longitudinal direction, the width of the protruding portion along the vehicle's longitudinal direction is large. Furthermore, in one embodiment of the present invention, the battery case is composed of a front case located in front of the vehicle and a rear case located behind the front case, and the upper surface of the rear end of the front case and the upper surface of the front end of the rear case are joined together. [Effects of the Invention]

[0006] According to one embodiment of the present invention, multiple protruding sections, each composed of a plurality of pairs of inclined surfaces and a plurality of lower surfaces connecting the lower ends of the pairs of inclined surfaces, are continuously formed at intervals in the longitudinal direction of the vehicle. Therefore, when an object falling from the road surface collides with a protruding section, the load is transmitted from the lower surface to the upper surface via the pair of inclined surfaces. As a result, the load is distributed into vertical and horizontal loads and transmitted to the battery case, so that the collision energy is efficiently absorbed by the battery case. Therefore, it is possible to reliably protect the battery pack from falling objects without having to significantly increase the ground clearance of the battery case. In other words, it is extremely advantageous in protecting the battery pack with a battery case without sacrificing space in the vehicle's interior. Furthermore, multiple recesses extending in the vehicle width direction, convex upwards and open downwards, are formed between the inclined surfaces of the multiple protrusions. As a result, some of the airflow generates vortex-like flows within each recess, allowing most of the airflow to flow smoothly along the multiple undersides from the front to the rear of the vehicle without entering the recesses. Therefore, the resistance the airflow along the undersides experiences from the battery case is minimized, which is advantageous in ensuring the vehicle's aerodynamic performance. Furthermore, by attaching the battery case to the bottom of the battery pack with multiple top surfaces spaced apart in the vehicle width direction, the resistance that the airflow along the underside receives from the battery case can be minimized, which is advantageous in ensuring the vehicle's aerodynamic performance. Furthermore, positioning the ends of the battery case, located in the central region of the vehicle's longitudinal direction, to be further outward in the vehicle width direction than the ends of the battery pack in the vehicle width direction not only allows the battery case to efficiently absorb collision energy during a side collision, but also has the advantage of protecting the parts of the battery pack on both sides in the vehicle width direction from the collision load. Furthermore, forming the spacing between multiple protrusions in the longitudinal direction of the vehicle so that the distance between them is smaller at the front of the vehicle than at the center of the longitudinal direction is advantageous in ensuring the strength and durability of the battery case against impacts from falling objects, as well as in reducing the weight of the battery case. Furthermore, forming the raised sections with a smaller width along the vehicle's longitudinal direction, and a larger width in the center of the vehicle's longitudinal direction, is advantageous in ensuring the strength and durability of the battery case against impacts from falling objects, as well as in reducing the weight of the battery case. Furthermore, joining the upper surface of the rear end of the front battery case to the upper surface of the front end of the rear battery case minimizes air resistance, which is advantageous in ensuring the vehicle's aerodynamic performance. [Brief explanation of the drawing]

[0007] [Figure 1] This is a side view of the lower part of a vehicle to which the battery case according to the first embodiment is applied, as seen from the vehicle width direction. [Figure 2] This is a magnified section of Figure 1. [Figure 3] This is a bottom view of a vehicle to which the battery case according to the first embodiment is applied. [Figure 4] This is a cross-sectional view along line AA in Figure 3. [Figure 5] This is a cross-sectional view of a battery pack fitted with a battery case according to the second embodiment, and corresponds to the cross-sectional view along line AA in Figure 3. [Figure 6] This is a cross-sectional view of a battery pack fitted with a battery case according to the third embodiment, and corresponds to the cross-sectional view along line AA in Figure 3. [Modes for carrying out the invention]

[0008] (First Embodiment) Hereinafter, embodiments of the present invention will be described with reference to Figures 1 to 4. In the following diagrams, the symbol FR indicates the front of the vehicle, the symbol UP indicates the top of the vehicle, and the symbol HL indicates the width direction of the vehicle. As shown in Figure 1, the battery pack 14 is mounted on a vehicle 10 that is an electric vehicle driven solely by a motor, or a hybrid vehicle, or a plug-in hybrid vehicle that is driven by a motor and can be externally charged or powered, and supplies power to the motor. The battery case 12 in this embodiment protects the battery pack 14.

[0009] The battery pack 14, although not shown, is composed of a plurality of battery modules, an electrical unit that controls the battery modules, and a case 16 which consists of a tray 16A that houses the battery modules and the electrical unit, and a cover 16B that covers the top of the tray 16A. The tray 16A is equipped with a rectangular tray frame (not shown), and tray cross members 18 (Figure 3) are provided at multiple locations on the tray 16A, spaced apart in the vehicle's longitudinal direction, to increase the rigidity of the tray 16A. These tray frame and tray cross members 18 constitute the skeletal structure. As shown in Figure 3, when viewed from above, the contour of the battery pack 14 is largely secured in the longitudinal and width directions of the vehicle between the front wheels 20 and the rear wheels 22. As shown in Figure 1, the front and rear portions of the battery pack 14 and both sides in the vehicle width direction are attached to a pair of side sills 15 (Figure 3), which are vehicle frame members that extend in the vehicle's longitudinal direction on both sides in the vehicle width direction below the floor panel, and the battery pack 14 is located at the bottom of the vehicle 10.

[0010] As shown in Figures 1 and 3, the battery case 12 is a component that covers the bottom surface 1402 of the battery pack 14 and protects the battery pack 14 from falling objects on the road surface. The battery case 12 may be made of steel or synthetic resin. As shown in FIG. 2, the battery case 12 extends in the vehicle width direction, and has a protruding strip portion 30 constituted by a plurality of pairs of inclined surfaces 24, which are inclined such that cross-sections thereof taken along a vertical plane passing through the vehicle front-rear direction face each other in the vehicle front-rear direction and separate from each other as going upward, and a lower surface 26 connecting lower ends of the inclined surfaces 24 to each other. A plurality of protruding strip portions 30 are continuously formed at intervals in the vehicle front-rear direction via an upper surface 28 connecting upper ends of the inclined surfaces 24 to each other.

[0011] As shown in FIG. 3, both end portions in the vehicle width direction of the battery case 12 located in the central region in the vehicle front-rear direction are located further outward in the vehicle width direction than both end portions in the vehicle width direction of the battery pack 14. Therefore, both end portions in the vehicle width direction of the plurality of protruding strip portions 30 located in the central region in the vehicle front-rear direction and the plurality of upper surfaces 28 connecting adjacent protruding strip portions 30 are located at positions close to the inner side surface in the vehicle width direction of the side sill 15.

[0012] Also, as shown in FIG. 3, the battery case 12 is constituted by a front case 12A located on the vehicle front side, and a rear case 12B located on the vehicle rear side of the front case 12A. At the central portion in the vehicle front-rear direction of the tray 16A, the upper surface 28 at the rear end of the front case 12A and the upper surface 28 at the front end of the rear case 12B are overlapped and joined to each other respectively.

[0013] As shown in FIGS. 3 and 4, at a plurality of positions spaced apart in the vehicle front-rear direction of the battery case 12, and at positions of the plurality of upper surfaces 28 spaced apart in the vehicle width direction, the battery case 12 is attached from below to a bottom surface 1402 of the battery pack 14 including a tray frame, a tray cross member 18 and the like by bolts B. Note that an unillustrated rubber or synthetic resin cap is attached to an opening formed by the pair of inclined surfaces 24 and the lower surface 26 at both ends in the vehicle width direction of each protruding strip portion 30, so that intrusion of dust, foreign matters, rainwater and the like into the protruding strip portion 30 during traveling is prevented.

[0014] Next, the functions and effects will be described. According to this embodiment, multiple convex portions 30, each composed of a plurality of pairs of inclined surfaces 24 of the battery case 12 and a plurality of lower surfaces 26 connecting the lower ends of the pairs of inclined surfaces 24, are continuously formed at intervals in the front-rear direction of the vehicle. Therefore, when an object falling from the road surface collides with the protruding section 30, the load applied to the lower surface 26 of the protruding section 30 is transmitted to the upper surface 28 via the pair of inclined surfaces 24. As a result, the load is distributed by the pair of inclined surfaces 24 into a vertical load and a horizontal load (vehicle longitudinal direction) and transmitted to the battery case 12. Specifically, as the pair of inclined surfaces 24 deform so as to collapse upward, the load is distributed by the inclined surfaces 24 into vertical and horizontal loads, so that the collision energy is efficiently absorbed by the battery case 12. Therefore, the battery pack 14 can be reliably protected from falling objects without requiring a large ground clearance for the battery case 12. In other words, it is extremely advantageous in protecting the battery pack 14 with the battery case 12 without sacrificing space in the vehicle compartment.

[0015] The inclination angle between the pair of inclined surfaces 24 and the upper surface 28 can be set within a range greater than 0 degrees and less than 90 degrees, but an inclination angle of 45 degrees is most preferable. This is because a 45-degree inclination angle allows the vertical and horizontal loads on the inclined surface 24 to be distributed equally, which is advantageous for absorbing collision energy most efficiently in the battery case 12.

[0016] Furthermore, the airflow during driving flows along the lower surface 26 of the multiple protrusions 30 of the battery case 12, and in doing so, multiple recesses 32 (Figure 4) are formed between the inclined surfaces 24 of the multiple protrusions 30, extending in the vehicle width direction, with an upward convex shape and an open bottom. Because some of the airflow generates a vortex flow inside each recess 32, the majority of the airflow does not enter the inside of each recess 32, but flows smoothly along the multiple lower surfaces 26 from the front to the rear of the vehicle. Therefore, the airflow along the underside 26 can minimize the resistance it receives from the battery case 12, which is advantageous in ensuring the aerodynamic performance of the vehicle 10. Furthermore, in this embodiment, the battery case 12 is arranged by having multiple upper surfaces 28 spaced apart in the vehicle width direction attached to the bottom surface 1402 of the battery pack 14 via bolts B, so that the heads of the bolts B do not protrude from the multiple lower surfaces 26. Therefore, the airflow along the underside 26 can minimize the resistance it receives from the battery case 12, which is advantageous in ensuring the aerodynamic performance of the vehicle 10.

[0017] Generally, side collisions are more likely to occur in the central region of a vehicle in the longitudinal direction. Therefore, in this embodiment, the ends of the battery case 12 located in the central region in the longitudinal direction of the vehicle are located further outward in the vehicle width direction than the ends of the battery pack 14 in the vehicle width direction. Therefore, during a side collision, the collision load is applied to both ends in the vehicle width direction of the multiple protrusions 30 located in the central region in the longitudinal direction of the vehicle and the multiple upper surfaces 28 connecting adjacent protrusions 30 via the side sill 15. As a result, collision energy can be absorbed by deforming so that both ends of the multiple protrusions 30 located in the central region in the longitudinal direction of the vehicle and the multiple upper surfaces 28 connecting adjacent protrusions 30 in the vehicle width direction are crushed inward in the vehicle width direction. Therefore, in addition to absorbing collision energy during a side collision with a vehicle frame member such as the side sill 15, the battery case 12 can also efficiently absorb collision energy during a side collision. Furthermore, this is advantageous in protecting both sides of the battery pack 14 in the vehicle width direction from collision loads.

[0018] In this embodiment, the battery case 12 is composed of a front case 12A located at the front of the vehicle and a rear case 12B located behind the front case 12A, with the upper surface 28 at the rear end of the front case and the upper surface 28 at the front end of the rear case being joined together. Therefore, when the airflow along the lower surface 26 of the battery case 12 passes through the boundary between the rear end of the front case 12A and the front end of the rear case 12B, the resistance the airflow receives from the joint between the upper surface 28 of the rear end of the front case and the upper surface 28 of the front end of the rear case can be minimized, which is advantageous in ensuring the aerodynamic performance of the vehicle 10.

[0019] (Second Embodiment) Next, a second embodiment will be described with reference to Figure 5. In the following description of the embodiments, the same reference numerals are used for parts and components as in the first embodiment, and their descriptions are omitted or simplified. The description will focus on the parts that differ from the first embodiment. The inventors have discovered that, during driving, falling objects do not collide evenly with the battery case 12, but rather that more objects collide with the front portion of the battery case 12 than with the central and rear portions of the battery case 12 in the longitudinal direction of the vehicle. Therefore, in the first embodiment, all the protruding parts 30 were provided at equal intervals in the longitudinal direction of the vehicle, whereas in the second embodiment, the spacing between the multiple protruding parts 30 in the longitudinal direction of the vehicle was formed so that the distance between them was smaller at the front of the vehicle than at the center of the longitudinal direction of the vehicle. Here, the distance between the protruding portions 30 in the longitudinal direction of the vehicle is the distance D between the upper ends of a pair of opposing inclined surfaces 24 of adjacent protruding portions 30. The spacing D between the multiple protrusions 30 in the longitudinal direction of the vehicle is smaller in the area in front of the vehicle than in the center of the vehicle in the longitudinal direction.

[0020] According to the second embodiment, the spacing D between the multiple protrusions 30 at the front of the battery case 12, which are prone to collisions with falling objects, is made small. This allows for a larger number of protrusions 30 per unit area at the front of the battery case 12, which is advantageous in ensuring the strength and durability of the battery case 12 against collisions with falling objects. Furthermore, by making the spacing D between the multiple protrusions 30 in the center of the battery case 12 in the longitudinal direction of the vehicle large, the number of protrusions 30 per unit area in the center of the vehicle in the longitudinal direction can be suppressed, which is advantageous in reducing the weight of the battery case 12.

[0021] (Third embodiment) Next, a third embodiment will be described with reference to Figure 6. As described above, the inventors have discovered that during driving, falling objects do not collide with the battery case 12 evenly, but rather that more falling objects collide with the front portion of the battery case 12 than with the central and rear portions of the battery case 12 in the longitudinal direction of the vehicle. Therefore, in the first embodiment, the width of all the protruding portions 30 along the vehicle's longitudinal direction was uniform, whereas in the third embodiment, the width of the protruding portions 30 along the vehicle's longitudinal direction was formed to be smaller in the front of the vehicle, and larger in the center of the vehicle's longitudinal direction. Here, the width W of the protruding portion 30 along the vehicle's longitudinal direction is the dimension between the upper ends of the pair of inclined surfaces 24 that form the protruding portion 30.

[0022] According to the third embodiment, the width W of the protruding portion 30 at the front of the battery case 12, which is prone to collisions with falling objects, is made small along the vehicle's longitudinal direction. This allows for a larger number of protruding portions 30 per unit area at the front of the battery case 12, which is advantageous in ensuring the strength and durability of the battery case 12 against collisions with falling objects. Furthermore, by making the width W of the protruding portion 30 in the vehicle's longitudinal direction at the center of the battery case 12 larger, the number of protruding portions 30 per unit area in the vehicle's longitudinal direction at the center can be reduced, which is advantageous in reducing the weight of the battery case 12. [Explanation of symbols]

[0023] 10 vehicles 12 Battery Cases 12A Front Case 12B Rear Case 14 Battery Packs 1402 Bottom 15 Side sill 16 cases 16A Tray 16B Cover 18 Tray Cross Member 20 Front Wheel 22 Rear wheels 24 Slope 26 Bottom side 28 Top 30 raised section 32 recesses B bolt D. Distance between the protruding portions 30 in the longitudinal direction of the vehicle W width of the protruding portion 30 along the vehicle's longitudinal direction

Claims

1. A battery case that covers the bottom surface of a battery pack located at the bottom of a vehicle, The battery case has a convex portion that extends in the vehicle width direction and, when cut by a vertical plane passing through the vehicle's longitudinal direction, has a shape that consists of a pair of inclined surfaces that face each other in the vehicle's longitudinal direction and inclined to move away from each other as they rise, and a lower surface that connects the lower ends of the inclined surfaces. The aforementioned protruding portions are formed continuously in multiple locations at intervals in the vehicle's longitudinal direction, via an upper surface that connects the upper ends of the inclined surfaces. A battery case characterized by the following features.

2. The battery case is arranged such that its upper surface, which is spaced apart from the front and rear of the vehicle, is attached to the bottom surface of the battery pack. The battery case according to claim 1, characterized in that it is a battery case.

3. The ends of the battery case located in the vehicle width direction are positioned further outward in the vehicle width direction than the ends of the battery pack in the vehicle width direction. The battery case according to claim 1, characterized in that it is a battery case.

4. The spacing between the multiple protrusions in the longitudinal direction of the vehicle is smaller in the area in front of the vehicle than in the center of the longitudinal direction. The battery case according to claim 1, characterized in that it is a battery case.

5. In the front of the vehicle, the width of the aforementioned protruding portion along the longitudinal direction of the vehicle is formed to be small. In the central part of the vehicle in the longitudinal direction, the width of the protruding portion along the longitudinal direction of the vehicle is formed to be large. The battery case according to claim 1, characterized in that it is a battery case.

6. The battery case consists of a front case located at the front of the vehicle and a rear case located behind the front case. The upper surface of the rear end of the front case and the upper surface of the front end of the rear case are joined together. The battery case according to claim 1, characterized in that it is a battery case.

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