underbody structure

Abstract

A vehicle body lower structure includes a side frame (50) that links a battery pack (20) disposed below a floor portion (13) and a lower side beam (12), and a battery frame (38) that supports a battery (27) inside the battery pack (20). A first engagement flange (55) of the side frame (50) that engages with a case bottom portion (41) is disposed so as to overlap an upper side of a second engagement flange (75) of the battery frame (38) that engages with the case bottom portion (41) in the up-down direction.

Description

Technical Field

[0001] This invention relates to the lower structure of a vehicle body. Background Technology

[0002] As a lower body structure, there is a known structure in which a battery casing, which houses multiple batteries, is positioned below the vehicle floor. As a lower body structure, there is a known structure in which the two sides of the battery casing in the vehicle width direction are supported by a pair of lower side beams below the side of the vehicle body.

[0003] In such vehicles, it is crucial to protect the high-voltage battery inside the battery casing when a collision load is applied to the vehicle body to ensure collision safety performance.

[0004] Therefore, as a protection measure for the battery, a lower body structure has been proposed that has a rib or other easily damaged part (easily damaged part) in the crossbeam connected to the lower side beam located on the outer side of the vehicle width direction than the battery casing (for example, see Japanese Patent No. 3132261).

[0005] When a collision load is input from the side of the vehicle towards the inward direction in the vehicle width direction to the lower beam, the crossbeam begins to break down from the most vulnerable part. Therefore, it can absorb collision energy before the collision load deforms the battery casing. Summary of the Invention

[0006] However, in the aforementioned conventional vehicle body lower structure, after the easily crushed part is crushed upon the input of a collision load, it displaces into a block towards the battery. Therefore, the load is transferred from the easily crushed part to the battery, potentially damaging it. Thus, from the perspective of collision safety performance, there is still room for improvement.

[0007] The objective of this invention is to provide a vehicle body substructure that, upon the input of a collision load, prevents damage to the mounted battery while simultaneously and efficiently absorbing collision energy. Furthermore, it aims to provide a vehicle body substructure that improves collision safety performance and contributes to the development of sustainable transportation systems.

[0008] One embodiment of the present invention provides a vehicle body lower structure comprising: a side frame that connects a battery pack disposed below a floor portion to a lower side beam; and a battery frame that supports a battery inside the battery pack, wherein a first engagement flange in the side frame that engages with the battery pack is configured such that a second engagement flange in the battery frame that engages with the battery pack overlaps the upper side in the vertical direction.

[0009] In this configuration, the second engagement flange is arranged to overlap the upper side of the first engagement flange in the vertical direction. Both the first and second engagement flanges are formed in a manner that allows deformation relative to impact loads. Hereinafter, the portion including the first and second engagement flanges will sometimes be referred to as the "impact absorption portion".

[0010] Here, for example, when a collision load is applied to the first connecting flange of the side frame due to a side impact such as a side pillar collision, the second connecting flange presses down on the first connecting flange from above. Thus, the collision load causes the collision-absorbing section to deform downwards. Hereinafter, side impacts such as side pillar collisions will sometimes be abbreviated as "side impact".

[0011] The space below the impact absorption section ensures that it can accommodate the deformation of the impact absorption section. Therefore, it is possible to suppress the formation of crush residue in the impact absorption section and improve the impact energy absorption efficiency. By deforming the impact absorption section downward, it is possible to prevent the impact absorption section from contacting the battery disposed inside the battery pack.

[0012] Therefore, upon the input of a collision load, damage to the onboard battery can be prevented, while simultaneously absorbing collision energy efficiently. Thus, the lower structure of this vehicle body improves collision safety performance and contributes to the development of sustainable transportation systems.

[0013] In the above-described embodiment, the battery frame may have a curved portion formed at the end of the second engagement flange on the inner side in the vehicle width direction, and a protrusion protruding upward from the curved portion. The edge of the first engagement flange on the battery side extends to the curved portion side, and the edge has a first engagement portion that engages with the battery pack.

[0014] With this configuration, the edge of the first engagement flange extends to the curved side of the battery frame (i.e., the inner side of the vehicle width), and the first engagement portion of the edge engages with the battery pack. Therefore, the impact load can be transferred to the curved portion of the battery frame. Consequently, the curved portion can be used as the base point for bending relative to the impact load, allowing the first engagement flange to deform (bend) downwards more reliably together with the battery frame.

[0015] In the above scheme, the second engagement flange may also have a second engagement portion that engages with the battery pack, and the first engagement portion may be disposed at a position closer to the battery side than the second engagement portion.

[0016] With this configuration, the second engagement portion of the second engagement flange engages with the battery pack, and the first engagement portion is positioned closer to the battery side (i.e., the inner side of the vehicle width) than the second engagement portion. The second engagement flange is positioned on the upper side of the battery pack, and the first engagement flange is positioned on the lower side of the battery pack. This prevents direct contact between the first engagement flange and the battery.

[0017] Specifically, a scenario is also considered where, for example, an excessive impact load is applied to the first engagement flange of the side frame due to a side impact, causing the first engagement flange to deform upwards. In this case, the flange portion (i.e., the first engagement portion) also comes into contact with the battery frame. Therefore, the battery frame can suppress excessive upward deformation of the first engagement flange. Thus, the battery can be protected by the battery frame.

[0018] In the above scheme, the battery frame can also form a hollow cross section together with the battery pack in the protrusion, and the battery can be fastened to the inner end of the protrusion in the vehicle width direction of the battery frame.

[0019] With this configuration, the battery is securely connected to the inside of the protrusion in the vehicle width direction. Therefore, in the event of a side collision, the portion outside the vehicle width direction of the protrusion can be bent convexly from the center side of the protrusion. Consequently, when the first engaging flange deforms downward and the edge is concave, the protrusion can be bent convexly in cooperation with the concave bending of the edge. That is, the downward deformation caused by the outer portion of the battery in the battery pack (i.e., the impact absorption section) can be effectively guided. Therefore, the absorption efficiency of the impact energy generated by the impact absorption section can be improved, and the contact between the impact absorption section and the battery can be effectively suppressed.

[0020] In the above-described scheme, the protrusion of the battery frame may have a plurality of recesses that engage with the battery pack along the longitudinal direction of the vehicle.

[0021] With this configuration, the protrusion has a recess for engaging with the battery pack, and the recess can be positioned at the center of the protrusion in the width direction. Therefore, the recess increases the rigidity of the center of the protrusion in the width direction, creating a strength difference compared to the portion on the outer side in the width direction (i.e., the bending side). This allows the bending portion to be used more reliably as a bending base point, enabling the first engaging flange to deform (bend) downwards more reliably.

[0022] In the above-described scheme, the battery frame may also have a plurality of ridges that are spaced apart in the vehicle longitudinal direction and are continuous with the outer surface of the protrusion in the vehicle width direction and the second engagement flange, and extend in the vehicle width direction.

[0023] With this configuration, ridges are continuously formed on the outer surface of the protrusion and the second engagement flange on the battery frame, and multiple ridges are spaced apart in the longitudinal direction of the vehicle. Therefore, the rigidity of the second engagement flange can be improved relative to the collision load input by a side impact. As a result, the amount of collision energy absorbed by the collision absorption section equipped with the second engagement flange can be increased.

[0024] In the above scheme, the side frame may also have a horizontal portion fixed to the lower part of the lower side beam and a vertical portion connecting the horizontal portion to the first engaging flange. The horizontal portion and the vertical portion are formed as a hollow portion with a substantially L-shaped cross-section containing a plurality of hollow units. The second engaging flange of the battery frame is disposed at a position separated from the vertical portion in the vehicle width direction.

[0025] With this configuration, the horizontal and vertical portions of the side frame are formed into hollow portions with essentially L-shaped cross-sections, each containing multiple hollow units. The hollow portions exhibit high rigidity relative to the impact load input from a side collision. Therefore, by separating the second engagement flange of the battery frame inwards in the vehicle width direction relative to the vertical portion (i.e., the hollow portion), the gap between the battery frame and the hollow portion can be established. This effectively ensures the deformation of the impact absorption section relative to the impact load input from a side collision, further increasing the amount of impact energy absorbed.

[0026] In the above scheme, the wall thickness of the inner portion formed on the vertical side of the lower surface of the horizontal portion may be thinner than the wall thickness of the outer portion formed on the outer side in the vehicle width direction.

[0027] With this configuration, when a collision load is input due to a side impact, the collision load can actively deform the inner portion of the vertical side on the lower surface of the horizontal section. Therefore, the collision load can deform the junction between the vertical section and the first engagement flange upwards. As a result, the side frame can deform well, further increasing the amount of collision energy absorbed.

[0028] In the above scheme, the lower surface of the horizontal portion may be positioned below the lower surface of the battery pack, and the lower surface of the vertical portion may be formed as an inclined surface that rises from the lower surface of the horizontal portion toward the first engagement flange, and the lower surface of the vertical portion may connect the lower surface of the horizontal portion to the first engagement flange.

[0029] With this configuration, the lower surface of the horizontal section is positioned below the lower surface of the battery pack. Therefore, it is possible to suppress the hollow portion of the side frame from tilting inwards (i.e., inwards in the vehicle width direction) due to the impact load input from a side collision. Consequently, the first engagement flange of the side frame can deform downwards more reliably.

[0030] In the above-mentioned scheme, the battery can also be rectangular when viewed from above, with its long side facing the front-rear direction of the vehicle and positioned inside the battery pack.

[0031] With this configuration, the battery is positioned inside the battery pack with its long side facing the vehicle's longitudinal direction. Therefore, compared to arranging batteries of the same size and number with their long sides facing the vehicle's width, the battery's width-direction dimension can be reduced. In other words, the battery's width-direction dimension can be shortened without compromising its capacity.

[0032] This allows for a longer deformation travel of the impact-absorbing section located between the battery and the hollow section of the side frame. Furthermore, by minimizing the size of the battery support members in the vehicle width direction, vehicle weight reduction can be achieved, and by ensuring the battery capacity, the vehicle's driving range can be adequately guaranteed.

[0033] According to the solution of the present invention, damage to the onboard battery can be prevented upon input of a collision load, while simultaneously absorbing collision energy efficiently. Therefore, collision safety performance can be improved, contributing to the development of sustainable transportation systems. Attached Figure Description

[0034] Figure 1 This is a simplified diagram of a vehicle equipped with a battery pack and featuring the lower body structure of an embodiment of the present invention, viewed from the left side.

[0035] Figure 2 It is along Figure 1 A sectional view along line II-II.

[0036] Figure 3 This is a perspective view showing the state of the battery pack with the housing cover disassembled from an embodiment of the present invention.

[0037] Figure 4 It is along Figure 1 A three-dimensional view of the section cut along line IV-IV.

[0038] Figure 5 This is a perspective view of the battery casing in an embodiment of the present invention, showing the lower crossbeam, battery frame, and side frame disassembled.

[0039] Figure 6 From Figure 4 A cross-sectional view viewed in the VI direction.

[0040] Figure 7 This is a perspective view including a partial cross-section illustrating the state in which a collision load is input to the lower body structure of the vehicle body according to an embodiment of the present invention due to a side collision. Detailed Implementation

[0041] Hereinafter, a battery pack-mounted vehicle having an embodiment of the vehicle body lower structure according to the present invention will be described with reference to the accompanying drawings. In the drawings, arrow FR indicates the front of the vehicle, arrow UP indicates the top of the vehicle, and arrow LH indicates the left side of the vehicle. The battery pack-mounted vehicle has a generally bilaterally symmetrical structure.

[0042] Therefore, the same symbols will be used to label the components on the left and right sides for explanation.

[0043] Figure 1 This is a simplified diagram of the vehicle Ve, which has a battery pack mounted on the lower body structure, viewed from the left side. Figure 2 It is along Figure 1 A sectional view along line II-II.

[0044] like Figure 1 , Figure 2 As shown, the battery pack-equipped vehicle Ve includes a body 10, a battery pack 20 disposed in the lower center of the body 10, and a left side frame 50 and a right side frame 50 connecting the battery pack 20 to the body 10. Hereinafter, the battery pack-equipped vehicle Ve will sometimes be abbreviated as "vehicle Ve".

[0045] <Body>

[0046] The vehicle body 10 includes a lower side beam (lower side beam) 12 on the left side, a lower side beam (lower side beam) on the right side (not shown), and a floor plate 13.

[0047] The lower beam 12 on the left and the lower beam on the right (not shown) are roughly symmetrical.

[0048] Therefore, the lower beam 12 on the left side will be referred to as "lower beam 12" in the following description, and the description of the lower beam on the right side (which is not shown in the figure) will be omitted.

[0049] The lower side beam 12 forms a closed section by aligning the opening sides of the inner panel 15 and the outer panel 16, which are C-shaped when viewed from the front-rear direction of the vehicle. The inner panel 15 is positioned inside the vehicle width direction, and the outer panel 16 is positioned outside the vehicle width direction on the left. The lower side beam 12 is a highly rigid component that forms part of the frame of the vehicle body 10. The lower side beam 12 is positioned on the left outer side (outer side in the vehicle width direction) relative to the battery pack 20.

[0050] The lower side beam 12 extends along the left outer side of the bottom plate 13 in the vehicle width direction and in the vehicle front-rear direction.

[0051] The left outer side portion 13a of the floor portion 13 is provided on the lower side beam 12. The floor portion 13 forms the floor portion of the vehicle body 10.

[0052] A battery pack 20 is fixed to the lower side beam 12 and the bottom plate 13, etc. The lower side beam 12, the bottom plate 13, and the battery pack 20 constitute the lower structure of the vehicle body.

[0053] <Battery Pack>

[0054] Figure 3 This is a perspective view showing the state of the battery pack 20 with the housing cover 32 disassembled.

[0055] like Figure 2 , Figure 3 As shown, the battery pack 20 is positioned below the base plate 13 (i.e., Figure 1 (Under the floor of the vehicle Ve shown). The battery pack 20 includes a battery housing 22 and a battery module 24.

[0056] <Battery casing>

[0057] The battery housing 22 includes a housing body 31 and a box-shaped housing cover 32 that opens from the side of the housing body 31 on the top cover of the housing body 31. The housing body 31 includes: a housing portion 34 disposed below the battery module 24; a lower crossbeam 35 disposed on the housing portion 34; an upper crossbeam 36 disposed above the lower crossbeam 35; a plurality of connecting portions 37 connecting the upper crossbeam 36 disposed above the lower crossbeam 35; and a plurality of battery frames 38 supporting the battery module 24.

[0058] The housing portion 34 has a housing bottom 41 and a housing peripheral wall 42. The housing bottom 41 is disposed below the battery module 24. The housing bottom 41 is generally rectangular in shape when viewed from above. The housing bottom 41 forms the bottom of the battery housing 22.

[0059] A housing peripheral wall 42 is formed along the outer periphery of the bottom 41 of the housing. A flange portion 42a is integrally formed on the housing peripheral wall 42 in a manner extending outward. The flange portion 32a of the housing cover 32 is arranged to overlap with the flange portion 42a. A lower crossbeam 35, an upper crossbeam 36, a plurality of connecting portions 37, and a plurality of battery frames 38 are disposed inside the battery pack 20.

[0060] Figure 4 It is along Figure 1 A three-dimensional view of the section cut along line IV-IV. Figure 5 This is a perspective view showing the lower crossbeam 35, battery frame 38, and side frame 50 disassembled from the battery casing 22.

[0061] like Figure 4 , Figure 5As shown, a lower crossbeam 35 is disposed in the housing portion 34 (particularly the housing bottom 41). The lower crossbeam 35 is positioned centrally in the housing portion 34 in the vehicle's longitudinal direction and extends in the vehicle width direction. For example, the right end 35a of the lower crossbeam 35 contacts the right wall of the housing peripheral wall 42. For example, the left end 35b of the lower crossbeam 35 (see...) Figure 3 It contacts the left wall of the housing peripheral wall 42. Multiple battery frames 38 are provided at the front and rear of the vehicle body of the lower crossbeam 35 in the bottom of the housing 41.

[0062] The upper crossbeam 36 is positioned above the lower crossbeam 35 and is arranged along the lower crossbeam 35. A plurality of connecting parts 37 are spaced apart between the upper crossbeam 36 and the lower crossbeam 35 along the vehicle width direction.

[0063] Multiple connecting parts 37 are components that connect the lower crossbeam 35 and the upper crossbeam 36 in the vertical direction. Only the connecting part 37 on the left outer side in the vehicle width direction is shown in the figure.

[0064] The upper crossbeam 36, multiple connecting parts 37, and lower crossbeam 35 are joined together by mounting bolts (not shown) that pass through the upper crossbeam 36, multiple connecting parts 37, and lower crossbeam 35. In this state, the upper crossbeam 36 secures the battery module 24 from above.

[0065] The lower crossbeam 35, multiple connecting parts 37, and the upper crossbeam 36 are fastened together in the vertical direction by bolts, nuts, etc., to form structural components 45 (see reference). Figure 6 ) and base plate 13 (refer to Figure 2 The battery frame 38 is connected to a base plate frame (not shown). The base plate frame (not shown) is a highly rigid component that engages with the upper surface of the base plate portion 13. The battery frame 38 will be described later.

[0066] <Side Frame>

[0067] like Figure 2 , Figure 3 As shown, the left side frame 50 allows the battery pack 20 to be separated from the lower side beam 12 and arranged inwards in the vehicle width direction by connecting the battery pack 20 to the left lower side beam 12. The right side frame 50 allows the battery pack 20 to be separated from the lower side beam 12 and arranged inwards in the vehicle width direction by connecting the battery pack 20 to the right lower side beam (not shown). The left and right side frames 50 are approximately symmetrical. Therefore, the left side frame 50 will be referred to as "side frame 50" in the following description, and the description of the right side frame 50 will be omitted.

[0068] like Figure 2 , Figure 4 , Figure 5As shown, the side frame 50 is positioned to the left of the left side 24a of the battery module 24 (the left outer side of the battery 27 described later) in the vehicle width direction. The side frame 50 extends along the lower side beam 12 and the battery pack 20 in the vehicle longitudinal direction.

[0069] The side frame 50 has: a horizontal portion 53 fixed to the lower part 12a of the lower side beam 12 (specifically, the lower part of the inner plate 15); a vertical portion 54 fixed to the battery pack 20; and a first engagement flange 55 engaging with the battery pack 20.

[0070] The outer side of the horizontal portion 53 is fixed to the lower part 12a of the inner plate 15 by fastening structural members 58 such as bolts and nuts. The vertical portion 54 is integrally formed on the inner side of the horizontal portion 53 and stands upright. The horizontal portion 53 and the vertical portion 54 are formed into a hollow portion 52 with a substantially L-shaped cross-section containing multiple hollow units 61. Therefore, the rigidity of the hollow portion 52 is formed to be high.

[0071] The flange portion 42a of the housing body 31 and the flange portion 32a of the housing cover 32 are fixed to the top 62 of the vertical portion 54 by fastening connecting structural members 64 such as bolts and nuts. The vertical portion 54 is sandwiched between the horizontal portion 53 and the first engaging flange 55 in the vehicle width direction, connecting the horizontal portion 53 and the first engaging flange 55.

[0072] The first engagement flange 55 is integrally formed in the lower surface portion (lower surface) 67 of the vertical portion 54 on the inner side portion 67a. The first engagement flange 55 extends from the inner side portion 67a toward the inner side in the vehicle width direction. The first engagement flange 55 engages from below with the bottom of the housing of the battery pack 20 (i.e., the lower surface of the battery pack 20) ​​41.

[0073] Specifically, the first engagement flange 55 has a flange portion 55a on the battery module 24 side (i.e., the inner side in the vehicle width direction). The flange portion 55a has a first engagement portion 55b that engages with the lower surface 41a of the housing bottom 41. The first engagement portion 55b is joined to the lower surface 41a of the housing bottom 41 from below by means of metal inert gas welding, laser welding, or the like. That is, the first engagement flange 55 is disposed on the lower side of the housing bottom 41. Therefore, the battery pack 20 is connected to the lower side beam 12 via the side frame 50.

[0074] Figure 6 From Figure 4 A cross-sectional view viewed in the VI direction.

[0075] like Figure 2 , Figure 6As shown, the horizontal portion 53 has a flat lower surface portion (lower surface) 66 formed on the lower side of the hollow unit 61. The lower surface portion 66 has an inner portion 66a formed on the side of the vertical portion 54; and an outer portion 66b formed on the outer side in the vehicle width direction. The wall thickness T1 of the inner portion 66a is thinner than the wall thickness T2 of the outer portion 66b.

[0076] Furthermore, the horizontal portion 53 has a lower surface portion 66 positioned below the bottom 41 of the housing. The lower surface portion 67 of the vertical portion 54 is inclined at an upward slope from the lower surface portion 66 of the horizontal portion 53 toward the first engaging flange 55. Therefore, the lower surface portion 66 of the horizontal portion 53 and the first engaging flange 55 are connected by the inclined lower surface portion 67. It should be noted that the reasons for making the wall thickness T1 of the inner portion 66a thinner than the wall thickness T2 of the outer portion 66b, and the reasons for positioning the lower surface portion 66 of the horizontal portion 53 below the bottom 41 of the housing, will be explained in detail later.

[0077] <Battery Module>

[0078] like Figure 3 , Figure 4 As shown, the battery module 24 includes: a plurality of front-side batteries 27 disposed in front of the vehicle body at the lower crossbeam 35 extending in the vehicle width direction; and a plurality of rear-side batteries 27 disposed behind the lower crossbeam 35. That is, the lower crossbeam 35 extending in the vehicle width direction is disposed between the front-side batteries 27 and the rear-side batteries 27.

[0079] The front battery 27 and the rear battery 27 are rectangular when viewed from above, and are arranged inside the battery pack 20 with their long sides facing the front-rear direction of the vehicle. Multiple front batteries 27 and rear batteries 27 are arranged in rows along the width of the vehicle.

[0080] A battery module 24 for driving is configured by having multiple front-side batteries 27 and multiple rear-side batteries 27.

[0081] A lower crossbeam 35, multiple connecting parts 37, and an upper crossbeam 36 are arranged between the front battery 27 and the rear battery 27. Hereinafter, the front battery 27 and the rear battery 27 will sometimes be referred to as "battery 27".

[0082] <Battery frame>

[0083] The following is based on Figures 4-6 To illustrate the battery frame 38 of the housing body 31 and the first engagement flange 55 of the side frame 50.

[0084] like Figures 4-6As shown, the battery frame 38 connects the battery 27 of the battery pack 20 and extends along the longitudinal direction of the vehicle. The battery frame 38 has: a protrusion 71 protruding upward from the bottom 41 of the housing; a second engagement flange 75 extending from the lower outer end of the protrusion 71; a curved portion 76 formed at the end of the second engagement flange 75 on the inner side in the vehicle width direction; and a third engagement flange 77 extending from the lower inner end of the protrusion 71.

[0085] The protrusion 71 has: a top 72 spaced upwards relative to the bottom 41 of the housing; an outer surface portion 73 bent downwards from the outer edge of the top 72; and an inner surface portion 74 bent downwards from the inner edge of the top 72. The outer surface portion 73 forms the outer side of the protrusion 71 in the vehicle width direction. The inner surface portion 74 forms the inner side of the protrusion 71 in the vehicle width direction. The protrusion 71 is formed into a U-shaped cross-section by the top 72, the outer surface portion 73, and the inner surface portion 74.

[0086] The second engagement flange 75 extends outward in the vehicle width direction from the lower edge of the outer surface 73 along the upper surface 41b of the housing bottom 41. The second engagement flange 75 engages with the upper surface 41b of the housing bottom 41. Therefore, the second engagement flange 75 is disposed on the upper side of the housing bottom 41. The second engagement flange 75 is configured to overlap the first engagement flange 55 of the side frame 50 in a vertically overlapping manner, passing over the housing bottom 41.

[0087] The first portion where the first joining flange 55, the housing bottom 41, and the second joining flange 75 overlap is formed in a manner that allows deformation relative to the impact load. The second portion where the first joining flange 55 overlaps with the housing bottom 41 is also formed in a manner that allows deformation relative to the impact load. Hereinafter, the portion including the first portion and the second portion will sometimes be referred to as the "impact absorption portion 78".

[0088] The second engagement flange 75 is positioned at a distance L1 that is separated from the vertical portion 54 (i.e., the hollow portion 52) of the side frame 50 in the vehicle width direction. A specific example of engaging the second engagement flange 75 to the upper surface 41b of the bottom 41 of the housing will be described in detail later.

[0089] The bend 76 is located at the intersection of the second engaging flange 75 and the outer surface 73 of the protrusion 71. That is, the protrusion 71 protrudes upward from the bend 76. The edge 55a of the first engaging flange 55 is disposed below the bend 76. The edge 55a of the first engaging flange 55 on the battery module 24 (battery 27) side extends to the bend 76 side. The first engaging portion 55b of the edge 55a engages from below with the lower surface 41a of the housing bottom 41.

[0090] The third engagement flange 77 extends from the lower edge of the inner side portion 74 along the upper surface 41b of the housing bottom 41 in the vehicle width direction. The third engagement flange 77 engages with the upper surface 41b of the housing bottom 41.

[0091] The battery frame 38 is formed into a top hat shape through the protrusion 71, the second engagement flange 75 and the third engagement flange 77.

[0092] The battery frame 38 is fixed to the upper surface 41b of the housing bottom 41 by engaging with the second engaging flange 75 and the third engaging flange 77. In this state, the protrusion 71 together with the housing bottom 41 forms a hollow cross section (hollow closed cross section). Therefore, the protrusion 71 can improve rigidity.

[0093] The protrusion 71 has a plurality of recesses 81 along the vehicle's longitudinal direction. The plurality of recesses 81 are formed such that they are recessed downwards from the top 72 of the protrusion 71. The plurality of recesses 81 are spaced apart in the vehicle's longitudinal direction. The top 72 is located at the center of the protrusion 71 in the vehicle width direction. Therefore, the protrusion 71 can improve the rigidity of the portion at the center side in the width direction. The plurality of recesses 81 are joined from above to the raised portion 83 of the bottom 41 of the housing by spot welding or the like.

[0094] Here, the rigidity of the hollow portion 52 of the side frame 50 is high. That is, the rigidity of the protrusion 71 and the hollow portion 52 is higher than that of the collision-absorbing portion 78 between the protrusion 71 and the hollow portion 52 in the vehicle width direction. The collision-absorbing portion 78 is, for example, a portion that is allowed to deform with respect to the collision load input by a side collision. Therefore, when a collision load is input to the side frame 50, the collision-absorbing portion 78 sandwiched between the highly rigid hollow portion 52 and the highly rigid protrusion 71 can be well deformed by the collision load.

[0095] In the top 72 of the protrusion 71, a battery module 24 (battery 27) is fastened to the inner end in the vehicle width direction (i.e., the inner end in the vehicle width direction of the protrusion 71) 72a. That is, the battery module 24 is disposed inside the battery pack 20 while supported on the inner end 72a in the vehicle width direction of the protrusion 71.

[0096] The battery frame 38 is spaced apart in the longitudinal direction of the vehicle and has a plurality of ridges 85 that are continuous with the outer face 73 and the second engagement flange 75 and extend in the vehicle width direction. The plurality of ridges 85 are formed as ribs that bulge (protrude) from the outer face 73 and the second engagement flange 75 toward the opposite side of the bottom of the housing 41.

[0097] The second engagement flange 75 has a second engagement portion 75a between adjacent ridge lines 85 in the vehicle longitudinal direction. A plurality of second engagement portions 75a are configured to contact the upper surface 41b of the housing bottom 41. The plurality of second engagement portions 75a are joined to the upper surface 41b of the housing bottom 41 by spot welding or the like. Here, the first engagement portion 55b of the first engagement flange 55 is positioned at a separation distance L2 from the second engagement portion 75a of the second engagement flange 75 towards the battery module 24 (battery 27).

[0098] The function and effects of the vehicle body lower structure described above will be explained.

[0099] Figure 7 It is a three-dimensional diagram including a partial cross-section illustrating the state of the collision load F input to the lower structure of the vehicle body due to a side collision.

[0100] like Figure 4 , Figure 7 As shown, for example, in the case of a side impact such as a side column collision, the lower side beam 12 (refer to) Figure 2 When a collision load F is input, the input collision load F is transmitted to the side frame 50. The collision load F transmitted to the side frame 50 is transmitted to the first engagement flange 55 via the hollow portion 52. Hereinafter, side collisions such as side pillar collisions are sometimes referred to simply as "side collisions".

[0101] The impact load F is transmitted to the first engagement flange 55, thereby transmitting the impact load F to the impact absorption section 78. The impact absorption section 78 is a portion that is allowed to deform relative to the impact load F. Here, the second engagement flange 75 of the battery frame 38 is arranged to overlap the upper side of the first engagement flange 55 in the vertical direction. Therefore, when an impact load F is input to the first engagement flange 55, the second engagement flange 75 can press the first engagement flange 55 from above. As a result, the impact absorption section 78 can deform downward.

[0102] A space 90 is provided below the impact absorption section 78 to accommodate its deformation. Therefore, it is possible to suppress the formation of crush residue in the impact absorption section 78 and improve the impact energy absorption efficiency. In addition, by deforming the impact absorption section 78 downward, it is possible to prevent the impact absorption section 78 from contacting the battery 27 disposed inside the battery pack 20 (i.e., above the bottom 41 of the housing).

[0103] Therefore, when a collision load F is input, damage to the onboard battery 27 can be prevented, while simultaneously absorbing collision energy efficiently. Thus, the lower structure of this vehicle body improves collision safety performance and contributes to the development of sustainable transportation systems.

[0104] like Figure 6 , Figure 7 As shown, the edge 55a of the first engagement flange 55 extends to the curved portion 76 side of the battery frame 38 (i.e., the inner side of the vehicle width). The first engagement portion 55b of the edge 55a (also see...) Figure 4 It engages with the lower surface 41a of the bottom of the housing 41. Therefore, the impact load F can be transmitted to the bottom of the housing 41 and the curved portion 76 of the battery frame 38.

[0105] Therefore, the bending portion 76 can be used as the base point for bending relative to the impact load F. This allows the first engagement flange 55 to deform (bend) downwards more reliably together with the housing bottom 41 and the battery frame 38 (especially the second engagement flange 75).

[0106] The second joint portion 75a of the second joint flange 75 (also refer to) Figure 4 The first engagement portion 55b is engaged with the upper surface 41b of the bottom 41 of the housing. The first engagement portion 55b is positioned closer to the battery 27 side (i.e., the inner side of the vehicle width) than the second engagement portion 75a. The second engagement flange 75 is positioned on the upper side of the bottom 41 of the housing, and the first engagement flange 55 is positioned on the lower side of the bottom 41 of the housing. This prevents the first engagement flange 55 and the bottom 41 of the housing from directly contacting the battery 27.

[0107] Specifically, a scenario is also considered where, for example, an excessive impact load is applied to the first engagement flange 55 of the side frame 50 due to a side impact, causing the first engagement flange 55 to deform upwards. In this case, the flange portion 55a (i.e., the first engagement portion 55b) also contacts the battery frame 38 via the bottom 41 of the housing. Therefore, the battery frame 38 can suppress excessive upward deformation of the first engagement flange 55. Thus, the battery 27 can be protected by the battery frame 38.

[0108] Furthermore, the battery 27 is securely connected to the inner side of the protrusion 71 in the vehicle width direction. Therefore, in the event of a side collision, the outer portion 79 in the vehicle width direction can be bent convexly from the center side of the protrusion 71 in the vehicle width direction. Thus, when the first engaging flange 55 deforms downward and the edge 55a is concave, the protrusion 71 can be bent convexly in cooperation with the concave bending of the edge 55a. That is, the downward deformation caused by the outer portion of the battery 27 in the bottom 41 of the housing (i.e., the impact absorption portion 78) can be well guided. Therefore, the absorption efficiency of the impact energy generated by the impact absorption portion 78 can be improved, and the contact between the impact absorption portion 78 and the battery 27 can be well suppressed.

[0109] The top 72 of the protrusion 71 has a recess 81 that engages with the raised portion 83 of the bottom 41 of the housing, thereby allowing the recess 81 to be positioned on the central side in the width direction of the protrusion 71. Therefore, the rigidity of the central side in the width direction of the protrusion 71 can be improved by the recess 81, resulting in a strength difference relative to the portion on the outer side in the width direction (i.e., the portion on the side of the bent portion 76). This allows the bent portion 76 to be used more reliably as a bending base point, enabling the first engaging flange 55 to deform (bend) downwards more reliably.

[0110] like Figure 4 , Figure 7 As shown, ridges 85 are continuously formed on the battery frame 38, connecting the outer surface 73 of the protrusion 71 and the second engagement flange 75. Multiple ridges 85 are spaced apart in the vehicle's longitudinal direction. Therefore, the rigidity of the second engagement flange 75 can be increased relative to the collision load F input from a side impact. This increases the amount of collision energy absorbed by the collision absorption section 78 equipped with the second engagement flange 75.

[0111] like Figure 6 , Figure 7 As shown, the horizontal portion 53 and vertical portion 54 of the side frame 50 are formed into a hollow portion 52 with a substantially L-shaped cross-section. The hollow portion 52 contains a plurality of hollow units 61. The hollow portion 52 is formed with high rigidity relative to the collision load F input by a side impact. Therefore, by separating the second engaging flange 75 of the battery frame 38 inward in the vehicle width direction by a distance L1 relative to the vertical portion 54 (i.e., the hollow portion 52), the gap between the battery frame 38 and the hollow portion 52 can be separated. This ensures a good amount of deformation of the collision absorption portion 78 relative to the collision load F input by a side impact, further increasing the amount of collision energy absorbed.

[0112] Furthermore, the wall thickness T1 of the inner portion 66a is made thinner than the wall thickness T2 of the outer portion 66b.

[0113] Therefore, when a collision load F is input due to a side impact, the collision load F can actively deform the inner portion 66a on the vertical side of the lower surface portion 66 of the horizontal portion 53. Thus, the collision load F can deform the junction 56 between the vertical portion 54 and the first engagement flange 55 upwards as indicated by arrow A. It should be noted that the junction 56 is approximately equivalent to the inner portion 67a of the lower surface portion 67 in the vertical portion 54.

[0114] In this way, the collision load F causes the junction 56 to deform upward as shown by arrow A, thereby enabling the side frame 50 to deform well and further increasing the amount of collision energy absorbed.

[0115] Furthermore, the lower surface portion 66 of the horizontal portion 53 is positioned below the bottom 41 of the housing. Therefore, it is possible to suppress the hollow portion 52 of the side frame 50 from falling inwards towards the interior (i.e., the inner side in the vehicle width direction) due to the impact load F input from a side collision. Consequently, the first engaging flange 55 of the side frame 50 can deform downwards more reliably.

[0116] like Figure 3 , Figure 6 , Figure 7 As shown, the battery 27 is arranged inside the battery pack 20 with its long side facing the front-rear direction of the vehicle. Therefore, for example, compared to arranging batteries of the same size and number with their long sides facing the width of the vehicle, the width dimension of the battery 27 can be reduced. That is, the width dimension of the battery 27 can be shortened without compromising its battery capacity.

[0117] Therefore, the deformation travel of the impact absorption portion 78 located between the battery 27 and the hollow portion 52 of the side frame 50 can be ensured for a longer period. Furthermore, by minimizing the size of the support member of the battery 27 in the vehicle width direction, the vehicle's Ve (refer to) can be optimized. Figure 1 The vehicle's range is ensured by reducing the weight of the battery and by ensuring the battery capacity of the battery 27.

[0118] The technical scope of the present invention is not limited to the aforementioned embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0119] Furthermore, without departing from the spirit of the present invention, the constituent elements in the foregoing embodiments may be appropriately replaced with well-known constituent elements, and the foregoing variations may also be appropriately combined.

Claims

1. A vehicle body lower structure, wherein, The lower structure of the vehicle body includes: The side frame will connect the battery pack, which is positioned below the base plate, to the lower side beam; and A battery frame, which supports the batteries inside the battery pack, The first engagement flange in the side frame that engages with the battery pack is arranged such that the second engagement flange in the battery frame that engages with the battery pack overlaps the upper side in the vertical direction. The battery frame has a curved portion at the end of the second engagement flange on the inner side in the vehicle width direction, and has a protrusion protruding upward from the curved portion.

2. The vehicle body lower structure according to claim 1, wherein, The edge of the first engaging flange on the battery side extends to the curved side. The edge portion has a first engagement portion that engages with the battery pack.

3. The vehicle body lower structure according to claim 2, wherein, The second engagement flange has a second engagement portion that engages with the battery pack. The first joint is positioned closer to the battery side than the second joint.

4. The vehicle body lower structure according to claim 2, wherein, The battery frame forms a hollow cross-section together with the battery pack at the protrusion. The battery is fastened to the inner end of the protrusion in the vehicle width direction of the battery frame.

5. The vehicle body lower structure according to claim 4, wherein, The protrusion of the battery frame has a plurality of recesses along the longitudinal direction of the vehicle that engage with the battery pack.

6. The vehicle body lower structure according to claim 2, wherein, The battery frame has a plurality of ridges that are spaced apart in the vehicle longitudinal direction and are continuous with the outer surface of the protrusion in the vehicle width direction and the second engagement flange, and extend in the vehicle width direction.

7. The vehicle body lower structure according to claim 1, wherein, The side frame includes a horizontal portion fixed to the lower part of the lower side beam and a vertical portion connecting the horizontal portion to the first engaging flange. The horizontal portion and the vertical portion are formed into a hollow portion with a substantially L-shaped cross-section containing multiple hollow units. The second engagement flange of the battery frame is positioned at a point that separates from the vertical portion in the vehicle width direction.

8. The vehicle body lower structure according to claim 7, wherein, In the lower surface of the horizontal portion, the wall thickness of the inner portion formed on the vertical side is thinner than the wall thickness of the outer portion formed on the outer side in the vehicle width direction.

9. The vehicle body lower structure according to claim 7, wherein, The lower surface of the horizontal portion is positioned below the lower surface of the battery pack. The lower surface of the vertical portion is formed to be inclined at an upward slope from the lower surface of the horizontal portion toward the first engaging flange. The lower surface of the vertical portion connects the lower surface of the horizontal portion to the first engagement flange.

10. The vehicle body lower structure according to claim 1, wherein, The battery, when viewed from above, is rectangular, with its long side facing the front-rear direction of the vehicle and positioned inside the battery pack.

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