underbody structure

Abstract

The present application provides a vehicle body lower structure. The vehicle body includes a vehicle floor having a storage portion for a storage battery; a pair of lower side members (12) on the left and right; a front cross member (20) disposed at a front portion of the storage portion for the storage battery; a rear cross member disposed at a rear portion of the storage portion for the storage battery; and a storage battery cover (40) covering an upper portion of the storage battery. An expanded portion (20E) is provided at an end portion of the front cross member (20) on the vehicle width direction outer side, the expanded portion (20E) has an increased height in the up-down direction compared to a central region in the vehicle width direction of the front cross member (20), and a front-rear width is expanded toward the rear side of the vehicle compared to a front-rear width of the central region in the vehicle width direction. The storage battery cover (40) is made of metal and has an outer side connecting portion (50) connected to the expanded portion (20E) on the vehicle width direction outer side.

Description

Technical Field

[0001] This invention relates to a vehicle body underbody structure in which a battery storage section is disposed on the vehicle body floor. Background Technology

[0002] As a lower body structure of a vehicle, there are known structures that house the battery storage unit on the vehicle floor (for example, see Japanese Patent Application Publication No. 2015-214233).

[0003] The lower body structure described in Japanese Patent Application Publication No. 2015-214233 features lower side beams extending along the longitudinal direction of the vehicle body on both sides of the lower part of the passenger compartment, with the vehicle floor supported by these lower side beams. A battery storage compartment is located beneath the rear seats on the vehicle floor, and a battery storage box is installed within this compartment. Front and rear crossbeams, connecting the two ends in the vehicle width direction to the left and right lower side beams, are positioned before and after the battery storage compartment. The battery storage box, which houses the battery, is fixed to the front and rear crossbeams.

[0004] The vehicle body lower structure described in Japanese Patent Application Publication No. 2015-214233 has front and rear crossbeams positioned before and after the battery storage box. Therefore, if an impact load is input from one side of the vehicle to one of its lower beams, the front and rear crossbeams smoothly transfer the load to the other lower beam. This protects the battery storage box and its internal batteries from the input impact load. Summary of the Invention

[0005] The Japanese Patent Application Publication No. 2015-214233 describes a vehicle body lower structure with crossbeams positioned at the front and rear of a battery storage box that houses the battery. These crossbeams protect the battery storage box and the battery inside. Therefore, when considering large impact loads input from the side of the vehicle, the crossbeams must be large and robust, resulting in a larger battery storage area and increased vehicle weight.

[0006] The present invention provides a compact, lightweight, and reliably protective lower body structure for the battery, which enables the reinforcement of the battery storage area.

[0007] One embodiment of the present invention comprises a vehicle body lower structure including: a vehicle body floor having a battery storage section for housing a battery; a pair of left and right lower side beams disposed on both sides of the vehicle body floor in the vehicle width direction and extending along the front-rear direction of the vehicle body; a front crossbeam disposed at the front of the battery storage section and extending along the vehicle width direction, with each end of the front side beam in the vehicle width direction connected to the corresponding left and right lower side beams; a rear crossbeam disposed at the rear of the battery storage section; and a battery cover connected to the front crossbeam and the rear crossbeam, covering the top of the battery, wherein a widening section is provided at the outer end of the front crossbeam in the vehicle width direction, the height of the widening section is increased in the vertical direction compared to the central area of ​​the front crossbeam in the vehicle width direction, and the front-rear width is increased towards the rear of the vehicle than the front-rear width of the central area in the vehicle width direction; the battery cover is made of metal and has an outer connecting section connected to the widening section on the outer side in the vehicle width direction.

[0008] With the above structure, when an impact load is input from one side of the vehicle to one side of the lower beam, the impact load is transmitted through the front crossbeam to the other side of the lower beam. At the same time, the impact load input from one side of the lower beam to the widened portion of the front crossbeam is transmitted to the metal battery cover through the outer connecting portion on one side. The impact load transmitted to the battery cover is also transmitted through the outer connecting portion on the other side to the widened portion on the other side of the front crossbeam, and then through the widened portion to the lower beam on the other side. Therefore, in the lower body structure of this structure, impact loads input from one side of the vehicle can be distributed and transmitted to the other side of the vehicle using the metal battery cover.

[0009] Furthermore, in the aforementioned structure, the vertical height of the central region of the front crossbeam in the vehicle width direction is set lower than that of the widened portion at the ends. This allows for a smaller cross-section in the central region of the front crossbeam in the vehicle width direction, thereby increasing the volume within the battery storage compartment. On the other hand, the vertical height and front-rear width of the front crossbeam decrease from the widened portion on the outer side towards the central region in the vehicle width direction, making it prone to stress concentration at locations where the cross-sectional shape changes abruptly. However, since the widened portion of the front crossbeam is connected to the metal battery cover via an outer connecting portion, stress concentration at locations where the cross-sectional shape of the front crossbeam changes is mitigated. Therefore, with this structure, impact loads input from one side of the vehicle can be efficiently transferred to the other side, providing more reliable protection for the battery stored within the battery storage compartment.

[0010] Alternatively, the battery cover may have a front cover ridge extending from one side of the vehicle width direction along the upper edge of the front wall to the other side, and the widened portion of the front crossbeam may have a widened portion ridge extending in the vehicle width direction along the upper edge of the front wall of the widened portion, and the outer end of the battery cover in the vehicle width direction may overlap with the widened portion in such a continuous manner as the front cover ridge and the widened portion ridge.

[0011] In this configuration, when an impact load is applied from one side of the vehicle to the lower side beam, the impact load is transmitted to the metal battery cover via the widened ridge line of the front crossbeam and the front side cover ridge line of the battery cover. Therefore, the high-rigidity, continuous ridge lines of the widened section and the battery cover allow for efficient transfer of lateral impact loads to the other side of the vehicle. Consequently, this structure helps to prevent the front crossbeam from becoming too large and provides more reliable protection for the battery housed within the battery compartment.

[0012] It is possible that a rear side frame extending toward the rear of the vehicle is arranged inside the vehicle width direction of each of the left and right lower side beams. The battery cover has: an upper wall and the front wall; a side wall extending downward from the outer end of the upper wall in the vehicle width direction; and an end flange extending outward from the lower end of the side wall in the vehicle width direction and overlapping with the upper surface of the widened portion and the upper surface of the rear side frame. The front side cover ridge line is continuously provided across the boundary portion of the front wall and the upper wall, the boundary portion of the front wall and the side wall, and the boundary portion of the front wall and the end flange. The outer connecting portion has fixing points fixed to the widened portion on the two walls that intersect each other and sandwich the front side cover ridge line in the middle.

[0013] In this configuration, the outer connecting portion of the battery cover has fixing points on two intersecting walls that sandwich the front side cover ridge. This allows for efficient transfer of impact loads from the widened portion of the front crossbeam to the outer connecting portion via these two fixing points, thus mitigating deformation and damage to the battery cover's periphery when impact loads are applied from the side of the vehicle.

[0014] The fixing points may include: a first fixing point for fixing one side of the outer connecting portion to the front wall of the widening portion in the front-back direction; and a second fixing point for fixing the other side of the outer connecting portion to the upper wall of the widening portion in the vertical direction.

[0015] In this configuration, the two intersecting walls of the outer connecting portion of the battery cover are securely fixed to the widened portion in both the longitudinal and vertical directions via a first fixing point and a second fixing point. Therefore, when an impact load is applied, rotational or torsional deformation of the battery cover around its axis along the vehicle width direction can be suppressed.

[0016] Furthermore, the outer connecting portion of the battery cover has a second fixing point that is fixed to the upper wall of the widened portion in the vertical direction. Therefore, when a passenger seat is installed above the battery cover, the vertical load on the seat side can be efficiently transferred to the widened portion. Thus, with this structure, seat swaying can be suppressed.

[0017] Alternatively, the sidewall of the battery cover may be inclined downwards from the outer end of the upper wall in the vehicle width direction, and the portion of the front side cover ridge line located at the boundary between the front wall and the sidewall may be an inclined ridge line portion that is inclined downwards from the outer end of the upper wall in the vehicle width direction. The first fixing point may be disposed at a position that overlaps with the inclined ridge line portion in the vehicle width direction, and the second fixing point may be disposed at a position that is further outwards in the vehicle width direction than the inclined ridge line portion.

[0018] In this case, the second fixing point, which fixes the outer connecting part of the battery cover to the upper wall of the widened part in the vertical direction, is positioned further outward in the vehicle width direction than the inclined ridge of the front side cover ridge. Therefore, impact loads input from the side of the vehicle can be widely dispersed to the inclined ridge of the battery cover and the side wall. Consequently, deformation (bending) of the inclined ridge caused by excessive concentration of impact loads at the inclined ridge of the battery cover can be suppressed.

[0019] Alternatively, the battery cover may have reinforcing ribs extending from the end flange across the sidewall.

[0020] In this case, the impact load input from the side of the vehicle is transmitted from the widened portion of the front crossbeam through the end flange and sidewall of the battery cover to the upper wall side of the battery cover.

[0021] At this point, because reinforcing ribs extending across the end flange and sidewall of the battery cover are provided, the impact load is efficiently transferred to the upper wall side while the deformation of the sidewall is suppressed by the reinforcing ribs.

[0022] Alternatively, the reinforcing rib may be positioned on the inside of the vehicle width direction of the fixing point located on the end flange.

[0023] In this case, when an impact load is applied from the side of the vehicle, a reinforcing rib is positioned further in the vehicle width direction than the fixing point on the end flange where the load is initially applied. Therefore, the impact load applied through the fixing point is reliably transferred to the upper wall of the battery cover via the reinforcing rib. Thus, with this structure, deformation of the side wall of the battery cover can be suppressed when an impact load is applied from the side of the vehicle, providing more reliable protection of the battery from impact loads.

[0024] Alternatively, the fixing point located on the end flange may be positioned between the front cover ridge and the reinforcing rib.

[0025] In this situation, the impact load input from the side of the vehicle is distributed to the upper wall of the battery cover via the fixing point on the end flange, the front cover ridge, and the reinforcing ribs. Therefore, with this structure, the deformation of the battery cover caused by the impact load can be further suppressed.

[0026] Alternatively, a plurality of reinforcing ribs may be arranged in a front-to-back configuration at a position relative to the rear of the vehicle from the fixing point located on the end flange. Each reinforcing rib is formed in a substantially triangular shape with its apex located on the upper side of the sidewall. The reinforcing ribs on the side closer to the fixing point are formed to be larger than the reinforcing ribs on the side farther from the fixing point.

[0027] In this configuration, each reinforcing rib is shaped such that its apex is located on the upper side of the sidewall of the battery cover, thus enabling efficient transfer of impact loads input to the end flange of the battery cover to the upper wall side of the battery cover. Furthermore, the reinforcing ribs closer to the fixing point are formed larger than those farther from the fixing point, thereby enabling more efficient transfer of impact loads input to the fixing point to the upper wall side of the battery cover near the front sidewall edge.

[0028] The battery cover may have: an upper wall and a front wall; a side wall extending downward from the outer end of the upper wall in the vehicle width direction; and an end flange extending outward from the lower end of the side wall in the vehicle width direction and overlapping the upper surface of the widened portion. The front side cover ridge line is continuously provided across the boundary between the front wall and the upper wall, the boundary between the front wall and the side wall, and the boundary between the front wall and the end flange. A side ridge line extending from the end of the front wall to the vicinity of the rear crossbeam is provided at the boundary between the side wall and the upper wall. A rear fixing point for fixing to the rear crossbeam is provided at the rear edge of the battery cover at a position closer to the rear end of the side ridge line in the vehicle width direction.

[0029] In this configuration, when an impact load is applied from one side of the vehicle to the widened portion of the front crossbeam, the impact load is transmitted along the front side ridge of the front crossbeam to the other side in the vehicle width direction. Furthermore, the load transmitted along the front side ridge to the upper front of the battery cover sidewall is transmitted to the rear edge of the battery cover via a side ridge extending from the front side ridge towards the rear of the vehicle, where it is received by the rear crossbeam at the rear fixing point. Therefore, with this structure, the impact load applied from one side of the vehicle to the front side ridge of the front crossbeam is efficiently dispersed towards the rear crossbeam, preventing excessive load concentration on the front crossbeam. This suppresses deformation of the front crossbeam, thus providing more reliable battery protection.

[0030] In the vehicle body lower structure of the present invention, the battery cover is made of metal, and an outer connecting portion that connects to the widened portion of the front crossbeam is provided at the outer end of the battery cover in the vehicle width direction. Therefore, impact loads input from one side of the vehicle can be dispersed to the metal battery cover and efficiently transferred to the other side of the vehicle. Thus, with the vehicle body lower structure of the present invention, the reinforcing structure around the battery storage section can be made smaller and lighter, while reliably protecting the battery. Attached Figure Description

[0031] Figure 1 This is a perspective view of the lower rear section of the vehicle body as seen from above.

[0032] Figure 2 It is along Figure 1 A sectional view along line II-II.

[0033] Figure 3 It is along Figure 1 A cross-sectional view along line III-III.

[0034] Figure 4 It is along Figure 1 A cross-sectional view along line IV-IV.

[0035] Figure 5 It is Figure 1 A magnified representation of a three-dimensional image. Detailed Implementation

[0036] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. It should be noted that, in the following description, unless otherwise specified, "front and back," "up and down," and "left and right" refer to directions relative to the vehicle's direction of travel. Furthermore, arrows indicating the front of the vehicle (FR), the top of the vehicle (UP), and the left side of the vehicle (LH) are shown in appropriate positions in the drawings.

[0037] Figure 1This is a perspective view of the lower rear part of the vehicle body 1 of this embodiment, viewed from the upper left front. Figure 2 It is along Figure 1 A sectional view along line II-II.

[0038] Figure 1 Symbol 10 refers to the front floor panel positioned below the passenger compartment. Symbol 11 refers to the rear floor panel positioned behind the front floor panel 10. Lower side beams 12, extending along the longitudinal direction of the vehicle body, are positioned on the left and right sides of the lower portion of the passenger compartment, serving as a skeletal frame. The front floor panel 10 is supported by the left and right lower side beams 12. The lower surface of the front floor panel 10 is supported by multiple floor frames (not shown). Furthermore, rear side frames 30, extending towards the rear of the vehicle body, are connected to the rearward side of the rear portion of each lower side beam 12 in the vehicle width direction. The rear floor panel 11 is supported by the left and right rear side frames 30.

[0039] It should be noted that the aforementioned front floor panel 10, rear floor panel 11, lower side beam 12, rear side frame 30, and the main components of the lower body described later are primarily made of metal.

[0040] A floor passage 15 extending along the longitudinal direction of the vehicle body is provided at the center of the front floor panel 10 in the vehicle width direction. The floor passage 15 is substantially formed as a downward opening. The cross-sectional shape (essentially U-shaped) The cross-sectional shape (essentially U-shaped) extends along the longitudinal direction of the vehicle body. The floor passage 15 bulges upward relative to the substantially flat base wall (substantially horizontally extending bottom wall) of the front floor panel 10.

[0041] Figure 3 It is along Figure 1 A cross-sectional view along line III-III. Figure 4 It is along Figure 1 A cross-sectional view along line IV-IV.

[0042] like Figure 3 , Figure 4 As shown, a front crossbeam 20 extending along the vehicle width direction is provided at the rear edge of the front floor panel 10. The front crossbeam 20 is constructed by joining multiple plates 22a, 22b, and 22c to a main crossbeam 21 that engages with the rear end of the front floor panel 10. The front crossbeam 20 has a substantially rectangular closed section 23 that extends along the vehicle width direction. The outer ends of the front crossbeam 20 in the vehicle width direction are connected to corresponding lower side beams 12 on the left and right sides.

[0043] like Figure 2As shown, the vertical height of the central region of the front crossbeam 20 in the vehicle width direction is lower than the height of the left and right end regions. Furthermore, Figure 3 , Figure 4 A comparison reveals that the left and right end regions of the front crossbeam 20 expand towards the rear of the vehicle relative to the front-to-rear width of the central region of the front crossbeam 20 in the vehicle width direction. Hereinafter, the expanded portion of the front-to-rear width of the left and right end regions of the front crossbeam 20 will be referred to as the "widening portion 20E".

[0044] like Figure 3 , Figure 4 As shown, the front crossbeam 20 includes a front wall 20f that rises upward from the rear of the front floor panel 10 and an upper wall 20u that bends substantially vertically from the upper end of the front wall 20f and extends toward the rear of the vehicle. The aforementioned front wall 20f and upper wall 20u are continuously formed over approximately the entire width of the front crossbeam 20. Therefore, the ridge line Lc formed by the bend between the front wall 20f and the upper wall 20u extends over approximately the entire width of the front crossbeam 20. Hereinafter, for ease of explanation, the portion of this ridge line Lc formed in the left and right widening portions 20E is referred to as the "widening portion ridge line Lce".

[0045] In addition, such as Figure 3 As shown, a rear crossbeam 25 extending along the vehicle width direction is provided at the front edge of the rear floor panel 11. The rear crossbeam 25 is formed by joining the rear edge of the relay floor panel 31 (described later) at the front edge of the rear floor panel 11. The rear crossbeam 25 has a substantially rectangular closed section 26 that extends along the vehicle width direction. The outer ends of the rear crossbeam 25 in the vehicle width direction are joined to the corresponding left and right rear side frames 30.

[0046] The aforementioned relay floor panel 31 is disposed between the front floor panel 10 and the rear floor panel 11. As described above, the rear edge of the relay floor panel 31 joins the front edge of the rear floor panel 11 to form a rear crossbeam 25. The front edge of the relay floor panel 31 joins the front crossbeam 20. The relay floor panel 31 is connected to the front floor panel 10 via the front crossbeam 20. A bottom wall portion 31b, recessed downward from the upper surfaces of both the front crossbeam 20 and the rear crossbeam 25, is provided between the front and rear edges of the relay floor panel 31.

[0047] The upper surface of the bottom wall portion 31b is provided with battery peripheral equipment such as a battery 32 used in vehicle drive and a control device (not shown) for power control. Furthermore, the outer end of the bottom wall portion 31b in the vehicle width direction is connected to the corresponding lower side beams 12 on the left and right.

[0048] In this embodiment, the front floor panel 10, the relay floor panel 31, and the rear floor panel 11 constitute the vehicle floor, and the bottom wall portion 31b of the relay floor panel 31 constitutes the battery storage portion.

[0049] The battery 32 and battery peripheral equipment housed in the bottom wall portion 31b (battery storage portion) of the relay floor panel 31 are covered by a metal battery cover 40. The battery cover 40 is connected to the front crossbeam 20 on the front side and the rear crossbeam 25 on the rear side by bolts or the like.

[0050] like Figure 1 , Figure 3 As shown, the battery cover 40 includes a rear flange 40rf that engages with the upper surface of the rear crossbeam 25 (the rear edge of the relay floor panel 31), an upper wall 40u that extends substantially horizontally forward after tilting upward towards the front side from the rear flange 40rf, and a front wall 40f that bends downward from the front end of the upper wall 40u. The upper wall 40u curves gently upward in the center of its width direction.

[0051] A rear seat (not shown) is fixedly installed on the upper part of the upper wall 40u of the battery cover 40. Therefore, the load of the rear seat and the passenger sitting in the rear seat acts on the upper wall 40u of the battery cover 40 from above.

[0052] Figure 5 It is Figure 1 A magnified representation of a three-dimensional image.

[0053] like Figure 1 , Figure 5 As shown, a sidewall 40s is formed at the outer end of the upper wall 40u of the battery cover 40 in the vehicle width direction, extending obliquely downward from this end in the vehicle width direction, and an end flange 40ef bends outward in the vehicle width direction from the lower end of the sidewall 40s and extends substantially horizontally. The end flange 40ef is formed to be continuous with the rear flange 40rf of the battery cover 40.

[0054] The front wall 40f of the battery cover 40 has extensions 40fe connected to its left and right sides on the outer side in the vehicle width direction. The central region of the front wall 40f of the battery cover 40 in the vehicle width direction bends downward from the front end of the upper wall 40u. In contrast, the left and right extensions 40fe bend downward from the front end of the side wall 40s and the front end of the end flange 40ef, and the side wall 40s extends obliquely downward from the outer end of the upper wall 40u in the vehicle width direction. Therefore, the front wall 40f of the battery cover 40 has a substantially trapezoidal shape in the main view, with the lower side longer than the upper side.

[0055] The battery cover 40 has a front side cover ridge line Lf that extends from one end to the other in the vehicle width direction along the upper edge of the front wall 40f, which includes left and right extensions 40fe. The front side cover ridge line Lf is continuous across the boundary between the central region of the front wall 40f in the vehicle width direction and the upper wall 40u, the boundary between the extension 40fe and the side wall 40s, and the boundary between the extension 40fe and the end flange 40ef.

[0056] Hereinafter, the portion of the front cover ridge line Lf located at the boundary between the extension 40fe and the side wall 40s will be referred to as the inclined ridge line portion Lfi. The portion located at the boundary between the extension 40fe and the end flange 40ef will be referred to as the end ridge line portion Lfe.

[0057] It should be noted that the battery cover 40 in this embodiment is constructed by joining multiple metal plates. However, the battery cover 40 may also be formed from a single metal plate.

[0058] Here, at the outer end of the battery cover 40 in the vehicle width direction, the end flange 40ef overlaps with the corresponding widening portions 20E on the left and right sides of the front crossbeam 20 and the upper surface of the rear side frame 30, and the extension 40fe of the front wall 40f overlaps with the front surface of the widening portion 20E (front surface of the front wall 20f). At this time, the outer end of the battery cover 40 in the vehicle width direction overlaps with the widening portion 20E in a manner where the front side cover ridge line Lf (end ridge line Lfe) of the battery cover 40 is continuous with the widening portion ridge line Lce of the widening portion 20E.

[0059] At the outer end of the battery cover 40 in the vehicle width direction, the extension 40fe of the front wall 40f is fixed to the front surface of the widened portion 20E by bolt B1, and the end flange 40ef is fixed to the upper surface of the widened portion 20E by bolt B2. Hereinafter, the bolt B1 that fixes the extension 40fe to the front surface of the widened portion 20E will be referred to as the first bolt B1, and the bolt B2 that fixes the end flange 40ef to the upper surface of the widened portion 20E will be referred to as the second bolt B2.

[0060] In addition, the central region of the front wall 40f of the battery cover 40 overlaps with the front surface of the front wall 20f of the front crossbeam 20 and is fixed to the front wall 20f of the front crossbeam 20 by a plurality of bolts (symbols omitted).

[0061] Furthermore, in this embodiment, the end flanges 40ef and the extension 40fe of the front wall 40f in the left and right directions of the vehicle width constitute the outer connecting portion 50 of the battery cover 40. Moreover, the fixing portion of the battery cover 40 based on the first bolt B1 constitutes the first fixing point in the outer connecting portion 50. The fixing portion of the battery cover 40 based on the second bolt B2 constitutes the second fixing point in the outer connecting portion 50. The first fixing point and the second fixing point are respectively provided on the two walls (the extension 40fe of the front wall 40f and the end flange 40ef) that intersect each other and sandwich the front side cover ridge line Lf in the middle.

[0062] The first bolt B1 is located at a position below the inclined ridge Lfi in the extension 40fe of the front wall 40f of the battery cover 40 (the position where it overlaps with the inclined ridge Lfi in the vehicle width direction), fixing the extension 40fe to the front wall 20f of the widening portion 20E in the longitudinal direction. The second bolt B2 is located at the end flange 40ef of the battery cover 40, located on the outer side in the vehicle width direction than the inclined ridge Lfi, fixing the end flange 40ef to the upper wall 20u of the widening portion 20E in the vertical direction. Furthermore, the second bolt B2 is located at a position near the front end of the end flange 40ef, close to the end ridge Lfe, fixing the end flange 40ef to the widening portion 20E.

[0063] Two reinforcing ribs 55a and 55b are formed across the end flange 40ef and side wall 40s of the battery cover 40. The reinforcing ribs 55a and 55b are positioned on the end flange 40ef at a location further rearward than the fixing point (second fixing point) based on the second bolt B2. The reinforcing ribs 55a and 55b are arranged separately at the front and rear of the vehicle body.

[0064] Each stiffener 55a and 55b is formed in a substantially triangular shape, with its apex located on the upper side of the sidewall 40s and its opposite sides located on the end flange 40ef. Each stiffener 55a and 55b bulges upwards and to the side relative to the sidewall 40s, and the lower end of the bulging portion is connected to the upper surface of the end flange 40ef. The stiffeners 55a and 55b enhance the rigidity of the sidewall 40s through a truss structure bulging from the sidewall of the sidewall 40s.

[0065] Furthermore, the two reinforcing ribs 55a and 55b are not the same size; the reinforcing rib 55a, located on the front side, is larger than the reinforcing rib 55b, located on the rear side. That is, regarding the bulge height and front-to-back width, the reinforcing rib 55a on the front side is set to be larger than the reinforcing rib 55b on the rear side.

[0066] Furthermore, the two reinforcing ribs 55a and 55b are positioned closer to the inside in the vehicle width direction than the fixing part (second fixing point) based on the second bolt B2 provided on the end flange 40ef. The fixing part (second fixing point) based on the second bolt B2 provided on the end flange 40ef is positioned between the end ridge Lfe (front cover ridge Lf) on the front end side of the end flange 40ef and the front reinforcing rib 55a.

[0067] The battery cover 40 also has a side ridge line Ls extending along the vehicle's longitudinal direction at the boundary between the upper end of the side wall 40s and the upper wall 40u. The front end of the side ridge line Ls intersects with the front side cover ridge line Lf, and the rear end extends to the vicinity of the rear crossbeam 25. The rear edge (rear flange 40rf) of the battery cover 40 is fixed to the rear crossbeam 25 by bolts B3 at a position closer to the vehicle width direction than the side ridge line Ls. Bolts B3 fix the rear edge of the battery cover 40 to the rear crossbeam 25 in the vertical direction.

[0068] In this embodiment, the fixing part based on bolt B3 constitutes the rear fixing point.

[0069] As described above, in this embodiment, the lower body structure has a widening portion 20E at the outer end of the front crossbeam 20 in the vehicle width direction, and the outer connecting portion 50 of the metal battery cover 40 is connected to the widening portion 20E. Therefore, when an impact load is input from one side of the vehicle 1 to one side of the lower beam 12, the impact load input from one side of the lower beam 12 to the widening portion 20E of the front crossbeam 20 is transmitted to the metal battery cover 40 through the outer connecting portion 50 on one side. The impact load transmitted to the battery cover 40 is also transmitted to the other side of the front crossbeam 20 through the other outer connecting portion 50, and then to the other side of the lower beam 12 through the other widening portion 20E.

[0070] Therefore, when an impact load is input from the side of the vehicle, the lower body structure of this embodiment can transmit the load via the metal battery cover 40 in parallel with the load transmission based on the front crossbeam 20. Thus, by adopting the lower body structure of this embodiment, the reinforcing structure around the battery storage section can be made smaller and lighter, and the battery 32 and surrounding equipment can be reliably protected.

[0071] Furthermore, in the lower body structure of this embodiment, the vertical height of the central region of the front crossbeam 20 in the vehicle width direction is set lower than that of the widened portion 20E at the ends. Therefore, the cross-section of the central region of the front crossbeam 20 in the vehicle width direction can be miniaturized, thereby increasing the volume of the battery storage compartment. Moreover, since the upper surface height of the central region of the front crossbeam 20 in the vehicle width direction is low, wiring harnesses such as wires extending from the battery storage compartment to the floor channel 15 can be easily routed across the upper surface of the front crossbeam 20.

[0072] However, the front crossbeam 20 decreases in both height and width from the widened portion 20E on the outer side in the vehicle width direction toward the central area, making it prone to stress concentration at locations where the cross-sectional shape changes abruptly. However, in the lower body structure of this embodiment, the widened portion 20E of the front crossbeam 20 is connected to the metal battery cover 40 via the outer connecting portion 50, thus mitigating stress concentration at locations where the cross-sectional shape of the front crossbeam 20 changes. Therefore, with this structure, impact loads input from one side of the vehicle 1 can be efficiently transferred to the other side of the vehicle 1, providing more reliable protection for the battery 32 housed within the battery storage compartment.

[0073] Furthermore, in this embodiment, the lower body structure has a front side cover ridge line Lf extending along the vehicle width direction at the upper edge of the front wall 40f of the battery cover 40, and a widening section ridge line Lce extending along the vehicle width direction at the upper edge of the front wall 20f of the widening section 20E of the front crossbeam 20. The outer end of the battery cover 40 in the vehicle width direction overlaps with the widening section 20E in a continuous manner with the front side cover ridge line Lf and the widening section ridge line Lce. Therefore, when an impact load is input from one side of the vehicle 1 to one side of the lower side beam 12, the impact load is transmitted to the metal battery cover 40 through the widening section ridge line Lce of the widening section 20E of the front crossbeam 20 and the front side cover ridge line Lf of the battery cover 40. Therefore, through the high-rigidity continuous ridge lines of the widening section 20E and the battery cover 40, impact loads from the side can be efficiently transmitted to the other side of the vehicle 1.

[0074] Therefore, by adopting this structure, it is possible to suppress the enlargement of the front crossbeam 20 and to more reliably protect the battery 32 and battery peripheral equipment housed in the battery storage section.

[0075] Furthermore, in the lower body structure of this embodiment, the outer connecting portion 50 of the battery cover 40 includes an extension portion 40fe that intersects with the front side cover ridge line Lf in the middle, and an end flange 40ef. A fixing portion (fixing point) based on a first bolt B1 and a fixing portion (fixing point) based on a second bolt B2 are respectively provided on the extension portion 40fe and the end flange 40ef. Therefore, the impact load input from the widened portion 20E of the front crossbeam 20 to the outer connecting portion 50 through the fixing point based on the first bolt B1 and the fixing portion based on the second bolt B2 can be efficiently transmitted to the front side cover ridge line Lf of the battery cover 40.

[0076] Therefore, with this structure, when an impact load is input from the side of the vehicle 1, the deformation and damage of the battery 32 and its surrounding parts can be further suppressed.

[0077] Furthermore, in the lower body structure of this embodiment, one wall (extension 40fe) of the outer connecting portion 50 is fixed to the front wall 20f of the widening portion 20E in the longitudinal direction based on the fixing part of the first bolt B1, and the other wall (end flange 40ef) of the outer connecting portion 50 is fixed to the upper wall 20u of the widening portion 20E in the vertical direction based on the fixing part of the second bolt B2. Therefore, the two intersecting walls (extension 40fe and end flange 40ef) of the outer connecting portion 50 are firmly fixed to the widening portion 20E in both the longitudinal and vertical directions by the first bolt B1 and the second bolt B2. Therefore, with this structure, when an impact load is input from the side of the vehicle, it is possible to suppress the rotational and torsional deformation of the battery cover 40 about the axis along the vehicle width direction.

[0078] Furthermore, in the lower body structure of this embodiment, since the outer connecting portion 50 of the battery cover 40 is fixed vertically to the upper wall 20u of the widened portion 20E via the second bolt B2, the seat load acting from the rear seat on the upper wall 40u of the battery cover 40 can be efficiently transferred to the widened portion 20E of the front crossbeam 20. Therefore, with this structure, the support rigidity of the rear seat can be improved, and the swaying of the rear seat can be suppressed.

[0079] Furthermore, in the lower body structure of this embodiment, the fixing part (first fixing point) of the outer connecting part 50 based on the first bolt B1 is arranged at a position overlapping with the inclined ridge Lfi of the front side cover ridge Lf in the vehicle width direction, and the fixing part (second fixing point) based on the second bolt B2 is arranged at a position further outward in the vehicle width direction than the inclined ridge Lfi of the front side cover ridge Lf. Therefore, the impact load input from the side of the vehicle to the outer connecting part 50 through the fixing part (second fixing point) based on the second bolt B2 can be widely dispersed to the inclined ridge Lfi of the battery cover 40 and the side wall 40s. Therefore, with this structure, deformation (bending) of the inclined ridge Lfi caused by excessive concentration of impact load on the inclined ridge Lfi of the battery cover 40 can be suppressed.

[0080] Furthermore, in this embodiment, the lower body structure is provided with reinforcing ribs 55a and 55b extending from the end flange 40ef across the side wall 40s at the outer connecting portion 50 of the battery cover 40. Therefore, when an impact load is input from the side of the vehicle 1, the impact load can be efficiently transferred to the upper wall 40u side of the battery cover 40 via the end flange 40ef and the side wall 40s by means of the reinforcing ribs 55a and 55b, while suppressing the deformation of the side wall 40s of the battery cover 40.

[0081] Furthermore, in this embodiment, the lower body structure has reinforcing ribs 55a and 55b positioned inward in the vehicle width direction from the fixing point (second fixing point) based on the second bolt B2 on the end flange 40ef of the outer connecting portion 50. Therefore, when an impact load is input from the side of the vehicle 1, reinforcing ribs 55a and 55b are positioned inward in the vehicle width direction from the fixing point (second fixing point) based on the second bolt B2 on the end flange 40ef where the load is initially input. Thus, with this structure, deformation of the sidewall 40s of the battery cover 40 can be suppressed when an impact load is input from the side of the vehicle 1, and the battery 32 and battery peripheral equipment can be protected more reliably from the impact load.

[0082] Furthermore, in the lower body structure of this embodiment, the fixing portion (second fixing point) based on the second bolt B2 on the end flange 40ef is disposed between the end ridge portion Lfe (front side ridge Lf) of the battery cover 40 and the reinforcing rib 55a. Therefore, impact loads input from the side of the vehicle 1 can be distributed to the upper wall 40u side of the battery cover 40 via the fixing portion (second fixing point) based on the second bolt B2 on the end flange 40ef and the front side ridge Lf and the reinforcing rib 55a. Therefore, with this structure, deformation of the battery cover 40 caused by impact loads can be further suppressed.

[0083] Furthermore, in the lower body structure of this embodiment, the reinforcing ribs 55a and 55b are arranged side-by-side, one behind the other, at a position closer to the rear of the vehicle than the fixing portion (second fixing point) based on the second bolt B2 on the end flange 40ef. Moreover, each reinforcing rib 55a and 55b is formed in a substantially triangular shape with its apex located on the upper side of the side wall 40s, and the reinforcing rib 55a closer to the fixing portion (second fixing point) based on the second bolt B2 is formed larger than the reinforcing rib 55b further away from this fixing portion. Therefore, via the two reinforcing ribs 55a and 55b having a truss structure, the impact load input to the end flange 40ef of the battery cover 40 can be efficiently transferred to the upper wall 40u side of the battery cover 40. Furthermore, since the reinforcing rib 55a on the side closer to the fixing part (second fixing point) based on the second bolt B2 is formed to be larger than the reinforcing rib 55b on the side farther away from the fixing part, the impact load input to the fixing part (second fixing point) based on the second bolt B2 can be transmitted more efficiently to the upper wall 40u side of the battery cover 40 near the front cover ridge line Lf.

[0084] Furthermore, in this embodiment, the lower body structure has a side ridge line Ls extending from the end of the front wall (front side ridge line Lf) to near the rear crossbeam 25 at the boundary between the side wall 40s and the upper wall 40u of the battery cover 40. The rear edge of the battery cover 40 is fixed to the rear crossbeam 25 by bolts B3 at a position closer to the rear end of the side ridge line Ls in the vehicle width direction. Therefore, when an impact load is input from one side of the vehicle 1 to the widened portion 20E of the front crossbeam 20, the impact load is transmitted along the front side ridge line Lf of the front crossbeam 20 to the other side in the vehicle width direction. On the other hand, the impact load is transmitted to the rear edge of the battery cover 40 via the side ridge line Ls extending from the front side ridge line Lf towards the rear of the vehicle, and is received by the rear crossbeam 25 through the bolt-based fixing portion at the rear edge.

[0085] Therefore, with this structure, the impact load input from one side of the vehicle 1 to the front side ridge line Lf of the front crossbeam 20 is efficiently distributed to the rear crossbeam 25 side, avoiding excessive load concentration on the front crossbeam 20. Thus, with this structure, deformation of the front crossbeam 20 can be suppressed, thereby providing more reliable protection for the battery 32 and battery-related equipment.

[0086] It should be noted that the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from its spirit.

[0087] For example, in the above-described embodiment, the battery storage unit and the battery cover are located at the rear of the vehicle compartment, but the battery storage unit and the battery cover may also be located in a location other than the rear of the vehicle compartment.

Claims

1. A vehicle body lower structure comprising: a vehicle body floor having a battery housing portion in which a battery is disposed; a pair of left and right lower side members disposed on both sides in a vehicle width direction of the vehicle body floor and extending in a vehicle longitudinal direction; a front cross member disposed at a front portion of the battery housing portion and extending in the vehicle width direction, each end portion on an outer side in the vehicle width direction being joined to a corresponding one of the left and right lower side members; a rear cross member disposed at a rear portion of the battery housing portion; and a battery cover covering an upper portion of the battery in conjunction with the front cross member and the rear cross member, wherein an enlarged portion is provided at an end portion of the front cross member on the outer side in the vehicle width direction, the enlarged portion having an increased height in a vertical direction and an increased width in the vehicle longitudinal direction compared to a central region in the vehicle width direction of the front cross member, and the battery cover is made of metal and includes an outer side connecting portion connected to the enlarged portion on the outer side in the vehicle width direction.

2. The vehicle body lower structure according to claim 1, wherein the battery cover has a front cover ridge line extending along an upper edge of a front wall from one side to the other side in the vehicle width direction, the enlarged portion of the front cross member has an enlarged portion ridge line extending in the vehicle width direction along an upper edge of a front wall of the enlarged portion, and an end portion of the battery cover on the outer side in the vehicle width direction overlaps the enlarged portion in such a manner that the front cover ridge line and the enlarged portion ridge line are continuous.

3. The vehicle body lower structure according to claim 2, wherein a rear frame extending toward the rear of the vehicle is disposed on an inner side in the vehicle width direction of each of the left and right lower side members, the battery cover has: an upper wall and the front wall; a side wall extending downward from an end portion on the outer side in the vehicle width direction of the upper wall; and an end portion flange extending outward in the vehicle width direction from a lower end of the side wall and overlapping an upper surface of the enlarged portion and an upper surface of the rear frame, the front cover ridge line is provided continuously across a boundary portion of the front wall and the upper wall, a boundary portion of the front wall and the side wall, and a boundary portion of the front wall and the end portion flange, the outer side connecting portion includes fixing points at which the two walls of the outer side connecting portion are fixed to the enlarged portion, and the fixing points include: a first fixing point at which a wall of the two walls of the outer side connecting portion is fixed to the front wall of the enlarged portion in the vehicle longitudinal direction; and a second fixing point at which the other wall of the two walls of the outer side connecting portion is fixed to the upper wall of the enlarged portion in the vertical direction.

4. The vehicle body lower structure according to claim 3, wherein the fixing points include: the first fixing point at which the wall of the two walls of the outer side connecting portion is fixed to the front wall of the enlarged portion in the vehicle longitudinal direction; and the second fixing point at which the other wall of the two walls of the outer side connecting portion is fixed to the upper wall of the enlarged portion in the vertical direction.

5. The vehicle body lower structure according to claim 4, wherein the side wall of the battery cover is inclined downward toward the outside in the vehicle width direction from the end portion on the outer side in the vehicle width direction of the upper wall, a portion of the front cover ridge line located at the boundary portion of the front wall and the side wall is an inclined ridge line portion inclined downward toward the outside in the vehicle width direction from the end portion on the outer side in the vehicle width direction of the upper wall, the first fixing point is disposed at a position overlapping the inclined ridge line portion in the vehicle width direction, and the second fixing point is disposed at a position on the outer side in the vehicle width direction than the inclined ridge line portion. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6. The underbody structure according to claim 3, wherein the battery case is provided with a reinforcement extending across the side wall from the end flange.

7. The underbody structure according to claim 6, wherein the reinforcement is disposed at a position inward in the vehicle width direction from the fixing point provided to the end flange.

8. The underbody structure according to claim 7, wherein the fixing point provided to the end flange is disposed between the front-side case ridge line and the reinforcement.

9. The underbody structure according to claim 7, wherein a plurality of the reinforcements are disposed in a front-rear direction at positions rearward of the fixing point provided to the end flange, each of the reinforcements is formed into a substantially triangular shape in a front view with an apex at an upper side of the side wall, the reinforcement on a side closer to the fixing point is formed larger than the reinforcement on a side farther from the fixing point.

10. The underbody structure according to claim 2, wherein the battery case has: an upper wall and the front wall; a side wall extending downward from an end on an outer side in the vehicle width direction of the upper wall; and an end flange extending outward in the vehicle width direction from a lower end of the side wall and overlapping an upper surface of the widened portion, the front-side case ridge line is continuously provided across a boundary portion of the front wall and the upper wall, a boundary portion of the front wall and the side wall, and a boundary portion of the front wall and the end flange, a side ridge line extending from an end on the front wall side to a vicinity of the rear cross member is provided at a boundary portion of the side wall and the upper wall, a rear-side fixing point fixed to the rear cross member is provided at a position inward in the vehicle width direction from a rear end portion of the side ridge line at a rear edge portion of the battery case.

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