Battery mounting structure

Abstract

To provide a battery mounting structure capable of more surely protecting a battery unit.SOLUTION: The battery mounting structure includes a battery unit 30 disposed under a vehicle floor and including a battery 32 and a battery case 34 housing the battery 32, and a side frame 16 disposed on an outer side in a vehicle width direction of the battery unit 30, wherein the battery case 34 includes a lower case 40, an upper case 50 covering an upper opening of the lower case 40 from above, and a sealing part 60 coupling the lower case 40 and the upper case 50 to seal the battery case 34, and the sealing part 60 is positioned on an upper side of an upper surface of the side frame.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This specification discloses a battery mounting structure under the floor of a vehicle. [Background technology]

[0002] Electric vehicles that run on the output power of a traction motor have been known for some time. Such electric vehicles are equipped with a battery unit that supplies power to the traction motor. The battery unit is often located under the floor of the vehicle. Furthermore, a battery case that houses the battery is usually composed of a lower case and an upper case. Patent Document 1 discloses a battery unit that has a lower case and an upper case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-165717 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, battery units have become larger to ensure greater charging capacity. As the battery units have become larger, the gap between the battery unit and the vehicle frame has become smaller. In this case, there is a risk that the battery unit may collide with the frame during a side collision. In particular, there is a risk that an impact may be applied to the sealing portion, which is the joint between the lower case and the upper case. In this case, the sealing portion may become unsealed, and the battery inside the battery case may not be adequately protected.

[0005] Therefore, this specification discloses a battery mounting structure that can more reliably protect the battery unit. [Means for solving the problem]

[0006] The battery mounting structure disclosed in this specification comprises a battery unit arranged under the vehicle floor and including a battery and a battery case that houses the battery, and side frames arranged on the outside of the battery unit in the vehicle width direction, wherein the battery case includes a lower case, an upper case that covers the upper end opening of the lower case from above, and a sealing portion that connects the lower case and the upper case and seals the battery case, and the sealing portion is located above the vehicle above the upper surface of the side frame.

[0007] In this case, furthermore, there may be an inner impact absorbing member that absorbs impact by crushing, the inner impact absorbing member including a vertical portion arranged between the side frame and the battery case, and the sealing portion including a lower flange that protrudes outward from the periphery of the lower case, and an upper flange that protrudes outward from the periphery of the upper case and is overlapped with the lower flange, and the vehicle width dimension of the vertical portion may be larger than the vehicle width dimension of the sealing portion that extends outward in the vehicle width direction from the side wall of the battery case.

[0008] In addition, the inner impact absorbing member may include the vertical portion and a horizontal portion extending outward in the vehicle width direction from the lower end of the vertical portion, the battery unit may include a base plate fixed to the bottom surface of the battery case and fastened to the bottom surface of the inner impact absorbing member, and the side frame may be placed on the horizontal portion and fastened to the inner impact absorbing member with a gap between it and the vertical portion.

[0009] The angle of the side surface relative to the bottom surface of the lower case may be substantially 90 degrees, and the shape of the side surface relative to the bottom surface of the lower case may be formed by roll forming.

[0010] The bottom surface of the battery unit may be located lower than the bottom surface of the side frame. [Effects of the Invention]

[0011] According to the technology disclosed in this specification, the sealing portion is positioned above the upper surface of the side frame, which effectively prevents the sealing portion from colliding with the side frame during a side collision. As a result, damage to the sealing portion is effectively prevented, and the battery unit is more reliably protected. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a cross-sectional view of the periphery of the battery unit. [Figure 2] FIG. 2 is an enlarged view of a portion of FIG. [Figure 3] FIG. 4 is a cross-sectional view of the battery unit and its surroundings in a side collision. [Figure 4] 10A and 10B are diagrams illustrating the relationship between the shape of the lower case and the mounting space for the battery. [Figure 5] FIG. 10 is a cross-sectional view of a mounting structure of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0013] The mounting structure of the battery 32 will be described below with reference to the drawings. Fig. 1 is a cross-sectional view of the periphery of the battery unit 30. Fig. 2 is a partially enlarged view of Fig. 1. Figs. 1 and 2 are cross-sectional views of the vehicle cut along a vertical plane parallel to the vehicle width direction, with the front of the paper being the front of the vehicle. In each figure, Fr, Up, and Rh indicate the front, upper, and right side of the vehicle, respectively.

[0014] The following describes a structure in which a battery 32 is mounted on a frame vehicle in which the frame is independent of the body. However, the technology disclosed in this specification is not limited to frame vehicles, and may also be applied to monocoque vehicles in which the frame and body are integrated. In this example, the battery unit 30 is disposed on the floor of the vehicle, i.e., below the floor panel 10 and floor reinforcement 12. In the following description, "reinforcement" will be abbreviated as "RF."

[0015] 1, both ends of the floor panel 10 in the vehicle width direction and both ends of the floor RF 12 in the vehicle width direction are joined to rockers 14. The rockers 14 are arranged one at each end of the vehicle width direction and are members that extend in the front-to-rear direction of the vehicle.

[0016] A pair of side frames 16 and a battery unit 30 are disposed under the floor of the vehicle. The side frames 16 are frame members that extend in the front-to-rear direction of the vehicle. The pair of side frames 16 are disposed on both sides of the battery unit 30 in the vehicle width direction.

[0017] As shown in FIG. 2 , the side frame 16 is broadly divided into a frame main body 18, a frame reinforcement 20, and a fastening bracket 22. The frame main body 18 is a tubular member having a substantially rectangular closed cross section, and is manufactured by, for example, extrusion molding. An opening is formed in the bottom surface of the frame main body 18 to allow a fastening bolt 84 to pass through. The frame reinforcement 20 is disposed in the internal space of the frame main body 18. Both ends of the frame reinforcement 20 in the vehicle width direction are joined to the side surfaces of the frame main body 18. In this way, the frame reinforcement 20 divides the internal space of the frame main body 18 into upper and lower sections, improving the rigidity of the frame main body 18.

[0018] The fastening bracket 22 is a panel member joined to the frame main body 18 so as to cover the bottom surface of the frame main body 18. A weld nut 24 is joined to the back surface of the fastening bracket 22 (i.e., the surface facing the bottom surface of the frame main body 18). In addition, a fastening hole concentric with the weld nut 24 is formed in the fastening bracket 22.

[0019] The battery unit 30 supplies power to a vehicle's traction motor (not shown). The battery unit 30 has a flat shape with its width and front-rear dimensions greater than its up-down dimension. The battery unit 30 includes a battery 32, a battery case 34 that houses the battery 32, and a base plate 36. The battery 32 is a secondary battery that supplies power to the vehicle's traction motor and stores power generated within the vehicle or supplied from outside the vehicle. The battery 32 is formed, for example, by electrically connecting multiple battery cells (not shown). As shown in FIG. 2, a bus bar 38 that electrically connects the battery cells extends in the up-down direction at the end of the battery 32 in the width direction.

[0020] The battery case 34 houses the battery 32. The battery case 34 has a lower case 40 that houses the battery 32, an upper case 50 that covers the upper opening of the lower case 40, and a sealing portion 60. The lower case 40 is a generally box-shaped member that includes a bottom wall 44 and peripheral walls that rise from the peripheral edges of the bottom wall 44. Hereinafter, of the peripheral walls of the lower case 40, the walls in the vehicle width direction will be referred to as "side walls 42." A lower flange 46 extends horizontally outward from the upper edges of the peripheral walls, including the side walls 42.

[0021] The angle α of the side wall 42 relative to the bottom wall 44 is substantially 90 degrees. "Substantially 90 degrees" refers to an angle that can be considered to have no draft. In other words, since a draft of 0.5 degrees or more is generally required when molding using a mold, "substantially 90 degrees" refers to an angle that is less than 0.5 degrees different from 90 degrees. The reason for setting the angle α to substantially 90 degrees will be described later. In this example, in order to make the angle α of the side wall 42 relative to the bottom wall 44 substantially 90 degrees, the shape of the side wall 42 relative to the bottom wall 44 is manufactured by roll forming.

[0022] A battery RF66 is fixed inside the lower case 40. The battery RF66 is a member for reinforcing the lower case 40 and is a member with a generally L-shaped cross section. As shown in FIG. 2 , one end of the battery RF66 is joined to the side wall 42, and the other end is joined to the bottom wall 44. This forms a closed cross section between the battery RF66 and the bottom wall 44 and the side wall 42. This closed cross section improves the rigidity of the lower case 40.

[0023] The upper case 50 is a lid-like member that includes a top wall 54 and a peripheral wall that hangs down from the periphery of the top wall 54. Hereinafter, of the peripheral walls of the upper case 50, the wall in the vehicle width direction will be referred to as the "side wall 52." An upper flange 56 extends horizontally outward from the lower edge of the peripheral wall, including the side wall 52.

[0024] The upper flange 56 is placed on the lower flange 46 and joined with a sealant or the like. This joint is a sealing portion 60 that seals the battery case 34. The sealing portion 60 joins the upper flange 56 and the lower flange 46 without any gaps. The sealing portion 60 seals the battery case 34, thereby preventing foreign matter, including water, from entering the battery case 34. Furthermore, sealing the battery case 34 makes it difficult for air from outside the case to enter the case. As a result, changes in the temperature and humidity around the battery 32 can be suppressed.

[0025] 2, the sealing portion 60 is located above the upper end of the side frame 16. In other words, the upper end of the lower case 40 is higher than the upper end of the side frame 16. This configuration is intended to prevent damage to the sealing portion 60, as will be described later.

[0026] The base plate 36 is a plate material joined to the bottom wall 44 of the lower case 40. A portion of the base plate 36 protrudes outward in the vehicle width direction from the lower case 40. The base plate 36, and therefore the battery unit 30, is fastened to the bottom surface of the inner impact-absorbing member 70 with fastening bolts 82. Note that hereinafter, the "impact-absorbing member" will be referred to as the "EA member."

[0027] 1, an outer EA member 80 and an inner EA member 70 are disposed on both the left and right sides of the side frame 16. Both the outer EA member 80 and the inner EA member 70 are members that actively crush during a vehicle side collision to absorb impact, thereby protecting the passenger compartment and on-board components.

[0028] The outer EA member 80 is disposed on the outer side of the side frame 16 in the vehicle width direction. The outer EA member 80 extends in a direction parallel to the side frame 16. As shown in FIG. 1, the internal space of the outer EA member 80 is divided into sections in the vertical and horizontal directions, and multiple small rooms are formed inside the outer EA member 80. The outer EA member 80 is formed, for example, by extrusion molding or roll molding.

[0029] The inner EA member 70 is disposed more inward in the vehicle width direction than the outer EA member 80. The inner EA member 70 also extends in a direction parallel to the side frame 16. As shown in FIG. 2 , the inner EA member 70 has a vertical portion 72 and a horizontal portion 74 extending outward in the vehicle width direction from the lower end of the vertical portion 72. The vertical portion 72 is located between the battery unit 30 and the side frame 16. The horizontal portion 74 is located below the side frame 16. The internal space of the inner EA member 70 is also divided into vertical and horizontal portions, and multiple small chambers are formed inside the inner EA member 70. The inner EA member 70 is formed, for example, by extrusion molding or roll molding.

[0030] The base plate 36 described above is fastened to the bottom surface of the vertical portion 72 by fastening bolts 82. Furthermore, the side frame 16 is fastened to the inner EA member 70 by fastening bolts 84 while placed on the horizontal portion 74. Therefore, the bottom surface of the battery unit 30 is lower than the bottom surface of the side frame 16. Furthermore, as shown in FIG. 2 , the vertical portion 72 of the inner EA member 70 is positioned close to the side wall 42 of the lower case 40, forming a slight gap between it and the side frame 16. With this arrangement, during a side collision, the horizontal portion 74 is crushed before the side frame 16 reaches the vertical portion 72. Then, as the horizontal portion 74 is crushed, impact energy is consumed, thereby reducing the impact transmitted to the vertical portion 72 and, ultimately, the battery unit 30.

[0031] Furthermore, the upper surface of the vertical portion 72 is positioned at approximately the same height as the upper surface of the battery RF66 and the frame RF20. This arrangement can prevent damage to the battery case 34 in the event of a side collision. Furthermore, the vehicle width dimension of the vertical portion 72 is greater than the vehicle width dimension of the sealing portion 60. The reason for this configuration will be described later.

[0032] Next, the reason for the above-mentioned configuration will be explained by comparing it with a comparative example. Fig. 5 is a diagram showing the mounting structure of the comparative example. In the comparative example shown in Fig. 5, the sealing portion 60* is located lower than the upper surface of the side frame 16. Furthermore, the vehicle width direction dimension of the sealing portion 60* is larger than the vehicle width direction dimension of the vertical portion 72 of the inner EA member 70.

[0033] With this configuration, in the event of a side collision, the sealing portion 60* may collide with the side frame 16, potentially releasing the seal of the sealing portion 60*. In other words, in the event of a side collision, the side frame 16 receives the impact and moves inward in the vehicle width direction. Meanwhile, the battery unit 30 rolls relatively outward in the vehicle width direction due to inertial force. As a result, the battery case 34 tilts as shown by the two-dot chain line in FIG. 5 . If the sealing portion 60* is lower than the top surface of the side frame 16, the sealing portion 60* may easily collide with the side frame 16.

[0034] Furthermore, even if the battery unit 30 does not roll, the sealing portion 60* is likely to collide with the side frame 16 that is moving inward in the vehicle width direction. In particular, if the vehicle width dimension of the sealing portion 60* is larger than the vehicle width dimension of the vertical portion 72 of the inner EA member 70, the sealing portion 60* will collide with the side frame 16 before the inner EA member 70 is crushed.

[0035] Then, when the sealing portion 60* strongly hits the side frame 16, the sealing portion 60* is damaged and the seal is released. As a result, a large amount of outside air flows into the battery case 34, causing a sudden change in the humidity and temperature around the battery 32. Furthermore, depending on the conditions around the battery unit 30, foreign matter such as water or dust may enter the battery case 34 from the location where the seal is released.

[0036] Note that, if the gap between the side wall 42 and the side frame 16 is increased, it is possible to prevent a collision between the sealing portion 60* and the side frame 16 to some extent. However, in order to increase the gap between the side wall 42 and the side frame 16, it is necessary to reduce the vehicle width direction dimension of the battery unit 30. In this case, another problem occurs in that the charging capacity of the battery 32 decreases by the amount of the reduction in the size of the battery unit 30. In other words, in the comparative example in which the sealing portion 60* is located below the upper surface of the side frame 16, there was a problem that the sealing portion 60* would be damaged in a side collision, or that the charging capacity had to be reduced to prevent damage.

[0037] On the other hand, as described above, in the battery case 34 of this example, the sealing portion 60 is located above the upper surface of the side frame 16. In this case, suppose that the battery 32 tilts toward the side frame 16 due to a side collision. In this case, the battery case 34 tilts as shown by the two-dot chain line in FIG. 3, but the sealing portion 60 is separated from the side frame 16 and does not easily collide with the side frame 16.

[0038] Furthermore, even if the battery unit 30 does not tilt, the side frame 16 moves inward in the vehicle width direction, i.e., in a direction approaching the battery unit 30. At this time, because the sealing portion 60 is located above the upper surface of the side frame 16, a collision between the sealing portion 60 and the side frame 16 and, ultimately, damage to the sealing portion 60 are effectively prevented. Furthermore, as described above, in this example, the vehicle width direction dimension of the vertical portion 72 of the inner EA member 70 is larger than the vehicle width direction dimension of the sealing portion 60. Therefore, before the side frame 16 collides with the battery unit 30, the vertical portion 72 is crushed, and impact energy is dissipated. As a result, even if the side frame 16 collides with the battery unit 30, the impact transmitted to the battery unit 30 is reduced, and the battery unit 30, including the sealing portion 60, is appropriately protected.

[0039] As is clear from the above explanation, in this example, the sealing portion 60 is disposed above the upper surface of the side frame 16, which effectively prevents damage to the sealing portion 60 in a side collision. In particular, even if the battery case 34 is brought closer to the side frame 16, damage to the sealing portion 60 can be prevented, which allows the size of the battery unit 30 to be increased, thereby ensuring a large battery charging capacity. Furthermore, in this example, the position of the sealing portion 60 is elevated, so naturally the distance from the road surface to the sealing portion 60 is also increased. This effectively prevents mud and stones from adhering to the sealing portion 60.

[0040] In this example, the sealing portion 60 is positioned above the top surface of the side frame 16, while the bottom surface of the battery unit 30 is positioned below the bottom surface of the side frame 16. This configuration ensures a sufficient thickness for the battery unit 30, ensuring a large battery charging capacity. However, in this case, the vertical dimension of the lower case 40 increases. In this case, if the side wall 42 is inclined, the storage space for the battery 32 decreases. This will be explained with reference to FIG. 4.

[0041] FIG. 4 is a schematic diagram comparing a lower case 40 manufactured by roll forming with a lower case 40 manufactured by press forming. As is well known, press forming requires a slight draft angle on the side of the product to allow it to be removed from the mold. Typically, this draft angle is 0.5 degrees or greater. Therefore, when the lower case 40 is manufactured by press forming, the angle α of the side wall 42 relative to the bottom wall 44 is 90.5 degrees or greater. Here, if the vertical dimension of the side wall 42 is small, the inclination of the side wall 42 resulting from this draft angle is hardly a problem. However, as shown in the bottom diagram of FIG. 4 , as the vertical dimension of the lower case 40 increases, the side wall 42 takes up more space in the vehicle width direction. As a result, the vehicle width dimension of the battery 32 that can be placed within the lower case 40 and, ultimately, the battery charging capacity are reduced.

[0042] Therefore, in this example, the angle α of the side wall 42 with respect to the bottom wall 44 is set to substantially 90 degrees. Because such an angle is difficult to obtain by press forming, in this example, the shape of the bottom wall 44 and the side wall 42 of the lower case 40 is manufactured by roll forming. Roll forming is a technique for shaping a steel sheet by passing the steel sheet between rollers with an array of multiple links and bending the steel sheet in stages.

[0043] When the angle α is substantially 90 degrees, the space occupied by the side wall 42 is reduced, as shown in the upper part of Fig. 4. This effectively prevents a decrease in the vehicle width direction dimension of the battery that can be placed inside the lower case 40, and in turn, a decrease in the battery charge capacity.

[0044] The configuration described above is merely an example, and other configurations may be modified as long as the configuration of claim 1 is met. For example, in the above example, the angle α of the side wall 42 relative to the bottom wall 44 of the lower case 40 is substantially 90 degrees. However, the angle α may be greater, and the shapes of the bottom wall 44 and the side wall 42 may be manufactured by press molding. Furthermore, as long as the sealing portion 60 is positioned above the upper surface of the side frame 16, its vehicle width dimension may be greater than the vehicle width dimension of the vertical portion 72. Furthermore, the bottom surface of the battery unit 30 may be positioned below the bottom surface of the side frame 16. Furthermore, in the above description, an inner EA member 70 and an outer EA member 80 are provided. However, as long as EA members are disposed between the battery unit 30 and the side frame 16, the number, shape, and arrangement of the EA members may be modified as appropriate. [Explanation of symbols]

[0045] 10 floor panel, 12 floor reinforcement, 14 rocker, 16 side frame, 18 frame body, 20 frame reinforcement, 22 fastening bracket, 24 weld nut, 30 battery unit, 32 battery, 34 battery case, 36 base plate, 38 bus bar, 40 lower case, 42 side wall, 44 bottom wall, 46 lower flange, 50 upper case, 52 side wall, 54 top wall, 56 upper flange, 60, 60* sealing portion, 66 battery reinforcement, 70 inner EA member, 72 vertical portion, 74 horizontal portion, 80 outer EA member, 82, 84 fastening bolt.

Claims

1. a battery unit disposed under a vehicle floor and including a battery and a battery case that houses the battery; a side frame disposed on the outer side of the battery unit in a vehicle width direction; The battery case comprises: Lower case and an upper case that covers an upper end opening of the lower case from above; a sealing portion that connects the lower case and the upper case to seal the battery case; the sealing portion is located above the upper surface of the side frame. A battery mounting structure characterized by:

2. The battery mounting structure according to claim 1, further comprising: an inner impact absorbing member that absorbs impact by collapsing, the inner impact absorbing member including a vertical portion disposed between the side frame and the battery case; The sealing portion is a lower flange extending outward from a peripheral edge of the lower case; an upper flange that protrudes outward from the periphery of the upper case and is overlapped with the lower flange; Including, a vehicle width direction dimension of the vertical portion is larger than a vehicle width direction dimension of the sealing portion extending from the side wall of the battery case outward in the vehicle width direction; A battery mounting structure characterized by:

3. The battery mounting structure according to claim 2, The inner impact absorbing member is The vertical portion; a horizontal portion extending outward in the vehicle width direction from a lower end of the vertical portion; Including, the battery unit includes a base plate fixed to a bottom surface of the battery case and fastened to a bottom surface of the inner impact absorbing member; The side frame is placed on the horizontal portion and fastened to the inner impact absorbing member with a gap between the side frame and the vertical portion. A battery mounting structure characterized by:

4. The battery mounting structure according to claim 1, The angle of the side surface of the lower case relative to the bottom surface is substantially 90 degrees, The shape of the side surface relative to the bottom surface of the lower case is formed by roll forming. A battery mounting structure characterized by:

5. The battery mounting structure according to claim 1, A battery mounting structure, characterized in that a bottom surface of the battery unit is located lower on the vehicle than a bottom surface of the side frame.

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