Substructure of vehicle

Abstract

To provide a substructure of a vehicle which can restrain fixation between a side sill and a battery from being off even if lateral collision load is inputted from outside of a vehicle width direction against the side sill.SOLUTION: A vehicle comprises a pair of side sills 10, a cross member 11, a battery 12 and a reinforcement member 13. The battery 12 is arranged below the cross member 11 and includes a battery frame 120. The reinforcement member 13 is stored in a hollow part 10a of the side sill 10 and at the same time includes a main body part 130 which is composed of a closed cross section structure and is arranged in an area that the main body part 130 overlaps with the cross member 11 at side view from one side of a vehicle width direction. The side sill 10 and the battery frame 120 and the reinforcement member 13 are fixed by engagement of a bolt BLT 1 and a nut NT 1. The bolt BLT 1 is inserted into a bracket 131 and its tip part penetrates toward the main body part 130 side of the reinforcement member 13.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle underbody structure, and more particularly to a vehicle underbody structure in which a battery is disposed under the floor. [Background technology]

[0002] In recent years, battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs) have rapidly become popular. In such vehicles, a large, high-capacity battery is installed under the floor. The battery installation configuration in the vehicle disclosed in Patent Document 1 will be described with reference to FIG. 8.

[0003] 8, in the vehicle of Patent Document 1, a battery frame 920 of a battery 92 is fixed to the lower part of a side sill 90. Specifically, the side sill 90 is configured by combining a side sill outer 900 on the outer side in the vehicle width direction and a side sill inner 901 on the inner side in the vehicle width direction, and the battery frame 920 is fixed to a lower wall portion 901c of the side sill inner 901 by threading a bolt BLT9 and a nut NT9.

[0004] A cross member 91 is also fixed to the side sill inner 901 of the side sill 90 so as to connect the side sill 90 to the side sill 90 on the opposite side in the vehicle width direction. The cross member 91 is disposed above the battery 92.

[0005] In the vehicle of Patent Document 1, a hollow portion 90a formed inside the side sill 90 accommodates a stiffener (reinforcing member) 93. The stiffener 93 is composed of a flat middle wall member 930 and an outer member 931 and an inner member 932, both of which have a hat-shaped cross section. The stiffener 93 is fixed to the side sill 90 by sandwiching an upper edge portion of the middle wall member 930 between an upper flange portion 900a of the side sill outer 900 and an upper flange portion 901a of the side sill inner 901, and by sandwiching a lower edge portion of the middle wall member 930 between a lower flange portion 900b of the side sill outer 900 and a lower flange portion 901b of the side sill inner 901.

[0006] In the vehicle of Patent Document 1, an inner member 932 of a stiffener 93 is formed in a hollow portion 90a so as to shift upward from the outer side to the inner side in the vehicle width direction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-131133 Summary of the Invention [Problem to be solved by the invention]

[0008] In the structure disclosed in Patent Document 1, there is a concern that when a side impact load is input to the side sill 90 on one side in the vehicle width direction, the side sill 90 on the other side in the vehicle width direction and the battery 92 may become disengaged. This will be explained using Figure 9. Figure 9 shows the behavior of the side sills 90L, 90R, the cross member 91, and the battery 92 when a side impact load F is input from the right side of the vehicle to the right side sill 90R.

[0009] As shown in Figure 9, when a side impact load F is input from the right side of the vehicle to the right side sill 90R, the cross member 91 is pressed leftward by the right side sill 90R as shown by arrow B1. The pressed cross member 91 is displaced leftward in accordance with the amount of deformation of the right side sill 90R (arrow B2). As a result, the side impact load F is transmitted to the left side sill 90L via the cross member 91.

[0010] Here, the battery 92 mounted under the floor is large and heavy, and therefore tends to remain in place due to inertia. As a result, the battery 92 experiences a displacement in the opposite direction (to the right) relative to the cross member 91 and the left side sill 90L. Therefore, as shown by arrow B3, there is a concern that the connection between the left side sill 90L and the battery 92 may break or become detached on the side opposite to the side where the side impact load F is input (on the left side).

[0011] In the above, we have explained the case where a side impact load F is input from the right side in the vehicle width direction. However, if a side impact load is input from the left side in the vehicle width direction, there is a concern that the right side sill 90R and the battery 92 may become detached from their fixed position.

[0012] The present invention has been made to solve the above-mentioned problems, and aims to provide a vehicle undercarriage structure that can prevent the side sill and battery from becoming detached even when a side impact load is input to the side sill from the outside in the vehicle width direction. [Means for solving the problem]

[0013] A vehicle undercarriage according to one aspect of the present invention includes a pair of side sills, a cross member, a battery, a reinforcing member, and a fixing member. The pair of side sills are disposed on both outer sides of the vehicle floor in the vehicle width direction, each extending in the front-rear direction of the vehicle and having a closed cross-sectional structure with a hollow portion therein. The cross member extends in the vehicle width direction and is fixed at both ends to the pair of side sills. The battery is disposed below the cross member under the vehicle floor and has a battery frame extending in the front-rear direction of the vehicle on the inner side of the pair of side sills in the vehicle width direction. The reinforcing member is housed in the hollow portion of each of the pair of side sills, has at least a portion formed with a closed cross-sectional structure, and is disposed in a region where the portion formed with the closed cross-sectional structure overlaps with the cross member in a side view from one side in the vehicle width direction. The fixing member fixes the battery frame to the pair of side sills.

[0014] In the vehicle undercarriage structure according to this aspect, the fixing member is disposed so that a portion of the fixing member penetrates the reinforcing member and fixes the battery frame to the side sill together with the reinforcing member.

[0015] In a vehicle to which the undercarriage structure according to the above aspect is applied, the portion of the reinforcing member that is configured with a closed cross-section structure is arranged in an area that overlaps with the cross member in the side view, so that a side impact load that is input to the side sill from the outside in the vehicle width direction is transmitted to the cross member with high efficiency. Also, on the opposite side in the vehicle width direction from the side where the load is input, the reinforcing member is arranged in an area that overlaps with the cross member in the side view, so that the load transmitted via the cross member is transmitted to the side sill efficiently via the reinforcing member.

[0016] Furthermore, in a vehicle to which the undercarriage structure according to the above aspect is applied, the reinforcing member and the battery frame are fixed to the side sill by a fixing member. Therefore, even when a side impact load is applied to the side sill from the outside in the vehicle width direction as described above, the battery frame, together with the cross member, is displaced toward the side opposite to the side from which the load was applied. Therefore, in the vehicle according to the above aspect, even when a side impact load is applied to one side sill, the side sill opposite to the side from which the load was applied can be prevented from coming loose from its fixed position.

[0017] Furthermore, because the batteries installed under the floor of electric vehicles and other vehicles are large, heavy, and have a large capacity, the battery frame is made with high rigidity. As a result, the battery frame, to which the load is transmitted via the fixing member, is less likely to deform or break more than the cross member, and there is less difference in relative displacement between the cross member and the battery frame when a side collision load is input.

[0018] In the vehicle lower structure relating to the above aspect, the reinforcing member may include a main body having a portion formed with the closed cross-sectional structure, and a bracket arranged below the main body, and the fixing member may be arranged so that a portion of the fixing member penetrates the bracket and fixes the bracket to the battery frame.

[0019] In a vehicle to which the undercarriage structure according to the above aspect is applied, the reinforcing member has a portion in which the main body is configured with a closed cross-sectional structure, and is fixed by a fixing member with a bracket. This ensures high rigidity of the reinforcing member when a side impact load is input, while also ensuring reliable fixation between the battery frame and the reinforcing member.

[0020] In the vehicle undercarriage structure according to the above aspect, the fixing member may be arranged so that a portion of the fixing member also penetrates into the main body portion.

[0021] In a vehicle to which the undercarriage structure of the above aspect is applied, a portion of the fixing member is arranged to penetrate into the main body of the reinforcing member, so that when a side impact load is input to the side sill, the battery frame can be more reliably displaced together with the cross member toward the side opposite to the side to which the load is input.

[0022] In the vehicle undercarriage structure relating to the above aspect, the fixing member may have a rod-shaped portion that penetrates into the main body portion, and the main body portion may have an opening at the portion where the part of the fixing member penetrates, the opening having a size larger than the cross-sectional size of the rod shape.

[0023] In a vehicle to which the undercarriage according to the above aspect is applied, the main body portion of the reinforcing member has an opening of the above-described size, and the rod-shaped portion of the fixing member penetrates through the opening. In other words, in the above aspect, when no side impact load is applied to the side sill, the fixing member and the inner circumferential surface of the opening in the main body are not in contact, thereby suppressing noise caused by a collision between the fixing member and the inner circumferential surface of the opening due to vibrations while the vehicle is traveling. On the other hand, when a side impact load is applied to the side sill and the reinforcing member is displaced due to deformation or displacement of the side sill, the outer surface of the rod-shaped portion of the fixing member comes into contact with the inner circumferential surface of the opening. As a result, a portion of the side impact load applied to the side sill is transmitted to the battery frame via the fixing member, displacing the battery frame together with the cross member during a side impact.

[0024] In the vehicle undercarriage structure according to the above aspect, the side sill may be configured to be fixed to the battery frame with a portion of the outer wall of the side sill sandwiched between the bracket and the battery frame.

[0025] In a vehicle to which the undercarriage structure according to the above aspect is applied, a portion of the outer wall of the side sill is sandwiched between the bracket of the reinforcing member and the battery frame, and the side sill, the reinforcing member, and the battery frame are fixed in this state by the fixing member. This allows the battery frame to be firmly fixed to the side sill and the reinforcing member. That is, compared to when the outer wall of the side sill is fixed with a gap between it and the bracket of the reinforcing member or the battery frame, when a side impact load is applied from the outside in the vehicle width direction, a difference in displacement between the cross member and the battery frame is less likely to occur due to resistance caused by surface contact between them. Therefore, even when a side impact load is applied to one side sill, this is more effective in preventing the side sill on the opposite side from the side to which the load is applied from becoming unfixed.

[0026] In the vehicle undercarriage structure according to the above aspect, the main body may be fixed to the side sill on at least one of the inner and outer sides in the vehicle width direction.

[0027] In a vehicle to which the undercarriage structure according to the above aspect is applied, the main body of the reinforcing member, including the portion having the closed cross-section structure, is fixed to the side sill, so that when a side impact load is applied to the side sill, the main body of the reinforcing member displaces inward in the vehicle width direction together with the side sill. As a result, the load is transmitted to the cross member by the main body of the reinforcing member displaced together with the side sill, and is also reliably transmitted to the battery frame via the fixing member.

[0028] In the vehicle undercarriage structure according to the above aspect, the bracket may be fixed to the main body portion.

[0029] In a vehicle to which the undercarriage structure according to the above aspect is applied, since the bracket is fixed to the main body, when a side impact load is input to the side sill, a relative difference in displacement in the vehicle width direction between the main body and the bracket is unlikely to occur. Therefore, even when a side impact load is input to one side sill, it is more effective in preventing the battery from being disengaged from the side sill on the opposite side from the side to which the load is input.

[0030] In the vehicle undercarriage structure according to the above aspect, the battery frame may have at least a portion having a closed cross-sectional structure, and the fixing member may fix the portion of the battery frame having the closed cross-sectional structure to the side sill and the reinforcing member.

[0031] In a vehicle to which the undercarriage structure according to the above aspect is applied, the battery frame is fixed to the side sill and the reinforcing member at the portion of the battery frame having the closed cross-section structure, which prevents the battery frame from being significantly deformed when a side impact load is applied to the side sill. Therefore, even when a side impact load is applied to one side sill, it is more effective in preventing the battery from being separated from the side sill on the opposite side from where the load is applied.

[0032] In the vehicle undercarriage structure relating to the above aspect, the fixing member may be arranged to extend upward in the vertical direction of the vehicle from the portion of the battery frame having the closed cross-sectional structure toward the reinforcing member.

[0033] In a vehicle to which the undercarriage structure according to the above aspect is applied, the fixing member is disposed so as to extend in the vertical direction, so that the battery can be raised from below the vehicle to above and the battery frame can be fixed to the side sill and the reinforcing member, eliminating the need for complicated work when installing the battery.

[0034] Furthermore, when a side impact load is input to the side sill, the load can be transmitted to the battery frame via the fixing member extending in the vertical direction.

[0035] In the vehicle undercarriage structure relating to the above aspect, each of the pair of side sills may include a side sill outer arranged on the outer side in the vehicle width direction and a side sill inner arranged on the inner side in the vehicle width direction and fixed to the side sill outer, and the battery frame and the reinforcing member may be fixed to the side sill inner by the fixing member.

[0036] In a vehicle to which the undercarriage structure according to the above aspect is applied, the battery frame and reinforcing member are fixed to the side sill inner, so that even if a side impact load is applied to a portion of the side sill, it is possible to prevent the joint (such as a welded joint) between the side sill inner and the vehicle body, such as the floor panel, from coming loose. In other words, when a side impact load is applied to the side sill, the side sill tends to deform into a dogleg when viewed from above and below. However, because the side sill and reinforcing member are fixed to the highly rigid battery frame, the reaction force from the battery frame prevents the side sill from deforming into a dogleg. Therefore, it is possible to prevent the joint between the side sill and the vehicle body from coming loose when a side impact load is applied to a portion of the side sill. [Effects of the Invention]

[0037] In a vehicle to which the undercarriage structure according to each of the above aspects is applied, the attachment between the side sill and the battery can be prevented from coming loose even when a side impact load is input to the side sill from the outside in the vehicle width direction. [Brief explanation of the drawings]

[0038] [Figure 1] 1 is a plan view showing a partial configuration of a vehicle to which an undercarriage structure according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a perspective view showing a partial configuration of a reinforcing member. [Figure 4] FIG. 2 is a perspective view showing the configuration of a bracket. [Figure 5] 10 is a schematic diagram for explaining the movement of a cross member and a battery when a side collision load is input to one of the side sills. FIG. [Figure 6] FIG. 10 is a cross-sectional view showing a lower structure according to a first modified example. [Figure 7] FIG. 10 is a cross-sectional view showing a lower structure according to a second modified example. [Figure 8] FIG. 1 is a cross-sectional view showing a lower structure according to the prior art. [Figure 9] 10 is a schematic diagram illustrating the movement of a cross member and a battery when a side impact load is input to a side sill in a conventional undercarriage structure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for the essential configuration.

[0040] In addition, in the figures used in the following explanation, "FR" indicates the front of the vehicle, "RR" indicates the rear of the vehicle, "LH" indicates the left side of the vehicle, "RH" indicates the right side of the vehicle, "UP" indicates the top of the vehicle, and "LO" indicates the bottom of the vehicle.

[0041] [Embodiment] 1. Vehicle 1 Configuration The configuration of a vehicle 1 to which an undercarriage according to this embodiment is applied will be described with reference to Fig. 1. Note that Fig. 1 illustrates only a portion of the configuration of the vehicle 1, and does not illustrate the powertrain or the like.

[0042] 1, a vehicle 1 has a powertrain mounting section 1a in the front where a powertrain is mounted, and a floor section 1b behind the powertrain mounting section 1a where passengers sit. A pair of side sills 10, multiple cross members 11, and a battery 12 are arranged on the floor section 1b.

[0043] A pair of side sills 10 are disposed on both sides of the floor portion 1b in the vehicle width direction, and each extends in the front-to-rear direction. A plurality of cross members 11 each extend in the vehicle width direction, and both ends are fixed to a pair of side sills 10. The battery 12 transmits and receives electric power to and from a powertrain (not shown).

[0044] The battery 12 includes battery cells made up of a lithium ion battery, a nickel-metal hydride battery, or the like.

[0045] 2. Fixing structure between the side sill 10, the cross member 11 and the battery 12 The fixing structure between the side sill 10, the cross member 11, and the battery 12 will be described with reference to Figures 2 to 4. Note that Figure 2 only shows the side sill 10 and its surrounding structure on the right side in the vehicle width direction, but the left side sill 10 and its surrounding structure have the same structure as the right side, except that they are reversed left and right.

[0046] 2, the side sill 10 has a closed cross-sectional structure with a hollow portion 10a inside. Specifically, the side sill 10 is formed by fixing a side sill outer member 100 and a side sill inner member 101, both of which have a hat-shaped cross section, at their upper flange portions 100a, 101a and at their lower flange portions 100b, 101b.

[0047] A reinforcing member 13 is housed in the hollow portion 10a of the side sill 10. The reinforcing member 13 includes a main body 130 having a closed cross-sectional structure and a bracket 131 disposed below the main body 130. As shown in FIGS. 2 and 3, the main body 130 of the reinforcing member 13 is formed to extend in the front-rear direction along the side sill 10. In contrast, a plurality of brackets 131 are provided at intervals from one another in the front-rear direction. The brackets 131 are fixed below the main body 130 at a location closer to the inside in the vehicle width direction.

[0048] The main body 130 and the bracket 131 are fixed to each other by inserting a nut (blind nut) NT3 into a through-hole opened in the main body 130 and threading a bolt BLT2 inserted from the bracket 131 side into the nut NT3. Although detailed illustration is omitted in Fig. 2, the outer diameter of the nut NT3 expands inside the main body 130 as the bolt BLT2 threads into the female thread, preventing it from coming off together with the bolt BLT2.

[0049] The main body 130 and the bracket 131 may be fixed together by providing a boss with an internal thread on the main body 130 and screwing the bolt BLT2 into the internal thread of the boss.

[0050] As shown in FIG. 4, each of the multiple brackets 131 has an opening 131j on one side in the vehicle width direction (in this embodiment, on the outer side in the vehicle width direction), and walls 131e to 131i are formed in the remaining portions. The bracket 131 is formed so that a bottom wall 131e and a top wall 131f face each other in the up-down direction, and side walls 131g and 131h face each other in the front-to-rear direction. A through-hole 131a is formed in the bottom wall 131e, and through-holes 131b to 131d are formed in the top wall 131f. The through-holes 131b and 131c are holes through which a nut NT3 and a bolt BLT2 are inserted, respectively. The through-hole 131a is a hole through which a bolt BLT1 used to secure the battery 12 is inserted, and the through-hole 131d is a hole (service hole) used when screwing the nut NT1 onto the bolt BLT1.

[0051] In this embodiment, the main body 130 of the reinforcing member 13 is fixed to the side sill inner panel 101. The main body 130 and the side sill inner panel 101 are fixed together by inserting a nut (blind nut) NT4 into through holes formed in the main body 130 and the side sill inner panel 101, and threading a bolt BLT3 inserted from the inside of the side sill inner panel 101 in the vehicle width direction into the nut NT4. Although detailed illustration of the nut NT4 is omitted in FIG. 2, threading of the bolt BLT3 into the female thread expands the outer diameter inside the main body 130, preventing the nut NT4 from coming off together with the bolt BLT3.

[0052] The main body 130 and the side sill inner 101 may be fixed together by providing a boss with an internal thread on the main body 130 and screwing the bolt BLT3 into the internal thread of the boss.

[0053] Each of the cross members 11 extends in the vehicle width direction, and both ends are fixed to the side sills 10. Note that various methods can be used to fix the side sills 10 and the cross members 11, such as bolting or welding.

[0054] When the reinforcing member 13 and the cross member 11 are viewed from the side in the vehicle width direction, the reinforcing member 13 and the cross member 11 are arranged in an overlapping positional relationship. Specifically, the main body 130 of the reinforcing member 13 is arranged in an overlapping positional relationship with the cross member 11 in a side view.

[0055] The battery 12 includes a housing formed by a battery frame 120 formed to surround the periphery in a direction intersecting the vertical direction, a bottom wall 121 fixed to the lower part of the battery frame 120, and a lid 122 fixed to the upper part of the battery frame 120. The battery cells (not shown) of the battery 12 are housed in a cell housing section 12a surrounded by the battery frame 120, the bottom wall 121, and the lid 122.

[0056] 2, the battery frame 120 has a closed cross-sectional structure and includes an extension portion 120a that extends outward in the vehicle width direction. The extension portion 120a has a through-hole through which a bolt BLT1 is inserted, and the bolt BLT1 passes through a through-hole (not shown) formed in the lower wall portion 101c of the side sill inner panel 101 and a through-hole 131a in the bracket 131 (see FIGS. 3 and 4) and penetrates into the bracket 131 of the reinforcing member 13. A nut NT1 is threaded onto the bolt BLT1 at the point where it penetrates into the bracket 131.

[0057] The bolt BLT1 in this embodiment has a rod-shaped shaft portion and corresponds to a fixing member.

[0058] In this embodiment, by screwing together the bolt BLT1 and the nut NT1, the lower wall portion 101c of the side sill inner panel 101 is fixed to the battery frame 120 in a state where it is sandwiched between the bracket 131 of the reinforcing member 13 and the battery frame 120. In other words, the battery frame 120 is fixed to both the side sill 10 and the reinforcing member 13.

[0059] 3. Behavior of the battery 12 when a side impact load is input to the side sill 10 The behavior of the battery 12 when a side impact load is input to the side sill 10 will be described using Figure 5. Note that the following description will be directed to a case where a side impact load F is input to the right side sill 10R from the outside in the vehicle width direction. The battery 12 will behave in the same way when a side impact load F is input to the left side sill 10L from the outside in the vehicle width direction, except that the left and right sides will be reversed.

[0060] As shown in Figure 5, when a side impact load F is applied to the right side sill 10R, the portion where the load F is applied deforms and displaces to the left (arrow D10R). When the side sill 10R displaces to the left, the reinforcing member 13R housed inside also displaces to the left. As a result, the cross member 11, which is disposed in the overlapping region in a side view, displaces to the left (arrow A1).

[0061] As described above, the battery 12 is fixed to the side sill 10R and the reinforcing member 13R by the bolt BLT1R, and therefore, as the side sill 10R and the reinforcing member 13R are displaced, the battery 12 also displaces to the left (arrow A3). In this manner, in the vehicle 1 of this embodiment, when a side collision load F is input to the side sill 10R, the cross member 11 and the battery 12 are displaced to the left with a small relative difference. Therefore, even if the left side sill 10L and the reinforcing member 13L are displaced and deformed as indicated by arrow A2 due to being pressed by the cross member 11, the bolt BLT1L that secures the side sill 10L and the reinforcing member 13L to the battery 12 is prevented from breaking (at the location indicated by arrow A4) and causing the battery 12 to come off the side sill 10L.

[0062] 4.Effects In a vehicle 1 to which the undercarriage structure according to this embodiment is applied, the main body 130 of the reinforcing member 13, which is configured with a closed cross-sectional structure, is arranged in a region that overlaps with the cross member 11 in a side view, so that a side impact load F input to the side sill 10 from the outside in the vehicle width direction is transmitted with high efficiency to the cross member 11. Moreover, the reinforcing member 13 is also arranged in a region that overlaps with the cross member 11 in a side view on the opposite side in the vehicle width direction from the side to which the side impact load F was input, so that the load transmitted via the cross member 11 is transmitted efficiently via the reinforcing member 13 to the side sill 10 (the side sill 10 on the opposite side to the side to which the side impact load F was input).

[0063] Furthermore, in the vehicle 1, the battery frame 120 is fixed not only to the side sill 10 but also to the reinforcing member 13 by the bolts BLT1. Therefore, even if a side impact load F is input to the side sill 10 from the outside in the vehicle width direction, the battery frame 120, together with the cross member 11, is displaced toward the opposite side from which the load was input. Therefore, in the vehicle 1, even if the side impact load F is input to one side sill 10 (the right side sill 10R in the example shown in FIG. 5), it is possible to prevent the battery 12 from being separated from the side sill 10 on the opposite side from which the side impact load F was input (the left side sill 10L in the example shown in FIG. 5).

[0064] The battery 12 mounted under the floor of an electric vehicle or the like is large and heavy, and therefore has a large capacity. For this reason, the battery frame 120 is formed with high rigidity. Therefore, the battery frame 120, to which a load is transmitted via the bolts BLT1, is unlikely to be deformed or damaged more than the cross member 11, and when a side collision load F is input to the side sill 10, a difference in relative displacement between the cross member 11 and the battery frame 120 is unlikely to occur.

[0065] Furthermore, in the vehicle 1 to which the undercarriage structure according to this embodiment is applied, the main body 130 of the reinforcing member 13 is configured to have a closed cross-sectional structure, and is fixed to the battery frame 120 by the bracket 131 and the bolt BLT1. This ensures high rigidity of the reinforcing member 13 when a side impact load F is input to the side sill 10, while reliably fixing the battery frame 120 and the reinforcing member 13 together.

[0066] Furthermore, in the vehicle 1 to which the understructure according to this embodiment is applied, the lower wall portion 101c of the side sill 10 is sandwiched between the bracket 131 of the reinforcing member 13 and the battery frame 120, and in this state, the side sill 10, the reinforcing member 13, and the battery frame 120 are fixed together by the bolt BLT1. This allows the battery frame 120 to be firmly fixed to the side sill 10 and the reinforcing member 13. That is, when a side collision load F is input to the side sill 10 from the outer side in the vehicle width direction, a difference in displacement between the cross member 11 and the battery frame 120 is less likely to occur due to resistance caused by surface contact between them, compared to when the lower wall portion 101c of the side sill 10 is fixed with a gap between it and the bracket 131 of the reinforcing member 13 or the battery frame 120. Therefore, even when a side impact load F is input to one of the side sills 10 (in the example shown in Figure 5, the right side sill 10R), this is more effective in preventing the battery 12 from coming loose from the side sill 10 on the opposite side from where the side impact load F is input (in the example shown in Figure 5, the left side sill 10L).

[0067] Furthermore, in the vehicle 1 to which the undercarriage structure according to this embodiment is applied, the main body 130 of the reinforcing member 13, which has a closed cross-sectional structure, is fixed to the side sill 10 by the bolt BLT3, so that when a side collision load F is input to the side sill 10, the main body 130 of the reinforcing member 13 is displaced inward in the vehicle width direction together with the side sill 10. Therefore, the load is transmitted to the cross member 11 by the main body 130 of the reinforcing member 13, which is displaced together with the side sill 10, and the load is also reliably transmitted to the battery frame 120 via the bolt BLT1.

[0068] Furthermore, in the vehicle 1 to which the undercarriage structure according to this embodiment is applied, the bracket 131 is fixed to the main body 130 by the bolt BLT2, so when a side impact load F is input to the side sill 10, a relative difference in displacement in the vehicle width direction is unlikely to occur between the main body 130 and the bracket 131. Therefore, even when the side impact load F is input to one side sill 10 (the right side sill 10R in the example shown in FIG. 5), this is more effective in preventing the battery 12 from being separated from the side sill 10 on the opposite side from where the side impact load F is input (the left side sill 10L in the example shown in FIG. 5).

[0069] Furthermore, in the vehicle 1 to which the undercarriage structure according to this embodiment is applied, the battery frame 120 also has a closed cross-sectional structure, which prevents the battery frame 120 from being significantly deformed when a side impact load F is input to the side sill 10. Therefore, even when the side impact load F is input to one side sill 10 (the right side sill 10R in the example shown in FIG. 5), this is more effective in preventing the battery 12 from being released from the fixation between the side sill 10 (the left side sill 10L in the example shown in FIG. 5) on the opposite side to where the side impact load F is input.

[0070] Furthermore, in the vehicle 1 to which the undercarriage structure according to this embodiment is applied, the bolts BLT1 are arranged to extend in the vertical direction, so the battery 12 can be raised from below the vehicle to above, and the battery frame 120 can be fixed to the side sill 10 and the reinforcing member 13. In other words, no complicated work is required when installing the battery 12.

[0071] Furthermore, when a side collision load F is input to the side sill 10, the load can be transmitted to the battery frame 120 via the bolt BLT1 extending in the vertical direction.

[0072] Furthermore, in the vehicle 1 to which the undercarriage structure according to this embodiment is applied, the battery frame 120 and the reinforcing member 13 are fixed to the side sill inner 101, so that even when a side impact load F is applied to a portion of the side sill 10 in the longitudinal direction, it is possible to prevent the joint (such as a welded joint) between the side sill inner 101 and the vehicle body, such as a floor panel, from coming loose. That is, when the side impact load F is applied to the side sill 10, the side sill 10 tends to deform into a dogleg in a plan view from the vertical direction. However, because the side sill 10 and the reinforcing member 13 are fixed to the battery frame 120, which has high rigidity, the reaction force from the battery frame 120 prevents the side sill 10 from deforming into a dogleg. Therefore, it is possible to prevent the joint between the side sill 10 and the vehicle body from coming loose when the side impact load F is applied to a portion of the side sill 10.

[0073] As described above, in a vehicle 1 to which the undercarriage structure of this embodiment is applied, the attachment between the side sill and the battery can be prevented from coming loose even when a side impact load is input to the side sill from the outside in the vehicle width direction.

[0074] [Variation 1] The lower structure according to Modification 1 will be described with reference to Fig. 6. The lower structure according to this modification is different from the above embodiment in the configuration of the reinforcing member 23, but the other configurations are the same as those of the above embodiment. The following describes the configuration of the reinforcing member 23, which is the difference from the above embodiment.

[0075] 6, the reinforcing member 23 includes a main body 230 including a portion having a closed cross-sectional structure, and a bracket 231 fixed to the battery frame 120. In the reinforcing member 23 of this modification, the main body 230 and the bracket 231 are spaced apart from each other and are not fixed to each other.

[0076] As in the above embodiment, the main body portion 230 of the reinforcing member 23 is disposed within the hollow portion 10a of the side sill 10 in a region that overlaps with the cross member 11 in a side view from the vehicle width direction. In this modified example, the main body portion 230 is fixed to the side sill outer 100. The main body portion 230 and the side sill outer 100 are fixed together by inserting a nut (blind nut) NT5 into through holes formed in the main body portion 230 and the side sill outer 100 and threading a bolt BLT5 inserted from the outside of the side sill outer 100 in the vehicle width direction into the nut NT5. Although detailed illustration of the nut NT5 is omitted in FIG. 6 , threading of the bolt BLT5 into the female thread expands the outer diameter inside the main body portion 130, preventing it from coming off together with the bolt BLT5.

[0077] The main body 130 and the side sill outer 100 may be fixed together by providing a boss with an internal thread on the main body 130 and screwing the bolt BLT5 into the internal thread of the boss.

[0078] In this modified example, the battery frame 120 also has a closed cross-sectional structure and includes an extension portion 120a that extends outward in the vehicle width direction. The extension portion 120a has a through-hole through which a bolt BLT4 is inserted, and the bolt BLT4 passes through a through-hole formed in the lower wall portion of the side sill inner panel 101 and a through-hole in the bracket 231, and partially penetrates into the hollow portion 230b in the main body portion 230 of the reinforcing member 23. A nut NT1 is threaded onto the bolt BLT4 on the bracket 231, thereby fixing the battery frame 120 to the side sill 10 and bracket 231.

[0079] Here, an opening 230c is provided in the main body 230 of the reinforcing member 23, through which the tip portion of the bolt BLT4 penetrates. The opening diameter (opening size) D1 of the opening 230c is larger than the outer diameter (cross-sectional size) D2 of the shank (penetrating portion) of the bolt BLT4. When no side collision load is input to the side sill 10, a gap is left between the outer peripheral surface of the shank of the bolt BLT4 and the inner peripheral surface of the opening 230c.

[0080] In this modification, the main body 230 of the reinforcing member 23 is not fixed to the battery frame 120.

[0081] It should be noted that the reinforcing member 23 does not necessarily have to include the bracket 231. That is, it is sufficient that a portion of the bolt BLT4 fixed to the side sill inner panel 101 by screwing into the nut NT2 passes through the opening 230c and penetrates into the main body portion 230.

[0082] The same effects as those of the above embodiment can be achieved in a vehicle to which the undercarriage according to this modification is applied. Furthermore, in this modification, an opening 230c with an opening diameter D1 is provided in the main body 230 of the reinforcing member 23, and the shank of the bolt BLT4 passes through the opening 230c and penetrates inward. That is, in this modification, when no side impact load is applied to the side sill 10, the shank of the bolt BLT4 does not contact the inner circumferential surface of the opening 230c of the main body 230. This can suppress noise caused by a collision between the shank of the bolt BLT4 and the inner circumferential surface of the opening 230c due to vibrations while the vehicle is traveling. On the other hand, when a side impact load is applied to the side sill 10 and the reinforcing member 23 is displaced inward in the vehicle width direction due to deformation or displacement of the side sill 10, the outer circumferential surface of the shank of the bolt BLT4 comes into contact with the inner circumferential surface of the opening 230c. As a result, part of the side collision load input to the side sill 10 is also transmitted to the battery frame 120 via the bolt BLT4, allowing the battery frame 120 to be displaced together with the cross member 11 during a side collision.

[0083] [Variation 2] The lower structure according to Modification 2 will be described with reference to Fig. 7. The lower structure according to this modification is different from the above embodiment in the configuration of the reinforcing member 33, but the other configurations are the same as those of the above embodiment. The following describes the configuration of the reinforcing member 33, which is the difference from the above embodiment.

[0084] 7, the reinforcing member 33 is configured by a main body 330 including a portion having a closed cross-sectional structure. That is, the reinforcing member 33 of this modified example does not include the brackets 131, 231 as in the above embodiment and modified example 1, and the battery frame 120 is directly fixed to the main body 330.

[0085] The bolt BLT6, which is inserted through the extension portion 120a of the battery frame 120, has its shaft portion inserted into the main body portion 330 of the reinforcing member 33. A boss 330a with an internal thread is formed at the portion of the main body portion 330 where the bolt BLT6 penetrates. The bolt BLT6 screws into the internal thread formed in the boss 330a, thereby fixing the battery frame 120 to the side sill 10 and the reinforcing member 33.

[0086] It should be noted that it is not essential to screw the bolt BLT6 into the female thread formed on the boss 330a when fixing the battery frame 120 to the main body 330 of the reinforcing member 33. For example, a nut may be disposed inside the main body 330, and the bolt BLT6 may be screwed into the nut to fix the battery frame 120 to the reinforcing member 33.

[0087] In this modified example, the reinforcing member 33 is fixed to the side sill inner panel 101. The reinforcing member 33 is fixed to the side sill inner panel 101 by inserting a nut (blind nut) NT6 into through holes formed in the main body 330 and the side sill inner panel 101, and threading a bolt BLT7 inserted from the inside of the side sill inner panel 101 in the vehicle width direction into the nut NT6. Although detailed illustration is omitted in FIG. 7 , threading of the bolt BLT6 into the female thread expands the outer diameter inside the main body 130, preventing it from coming off together with the bolt BLT7.

[0088] The main body 130 and the side sill inner 101 may be fixed together by providing a boss with an internal thread on the main body 130 and screwing the bolt BLT7 into the internal thread of the boss.

[0089] The lower structure according to this modified example differs from the above embodiment in that the reinforcing member 33 does not include a bracket, but the other configurations are the same and therefore the same effects as the above embodiment can be achieved.

[0090] [Other variations] In the above embodiment and the above first and second modifications, the bolts BLT1, BLT4, and BLT6 are used as the fixing members, but in the present invention, rivets or the like can also be used as the fixing members.

[0091] Furthermore, in the above embodiment and variant example 2, the main body portions 130, 330 of the reinforcing members 13, 33 are fixed to the side sill inner 101, and in variant example 1, the main body portion 230 of the reinforcing member 23 is fixed to the side sill outer 100, but in the present invention, there are no limitations on which of the side sill outer and side sill inner the main body portion of the reinforcing member is fixed to, as long as it can be fixed to at least one of the side sill outer and the side sill inner. [Explanation of symbols]

[0092] 1 vehicle 10 Side sill 11 Cross member 12 Battery 13, 23, 33 Reinforcement members 100 Side sill outer 101 Side sill inner 120 Battery Frame 130, 230, 330 Main body 131,231 Bracket 330a Boss BLT1, BLT4, BLT6 bolts (fixing members) NT1, NT2 nuts

Claims

1. a pair of side sills disposed on both outer sides of a floor of the vehicle in a vehicle width direction, each extending in a front-rear direction of the vehicle, and each having a closed cross-sectional structure with a hollow portion therein; a cross member extending in the vehicle width direction and having both ends fixed to the pair of side sills; a battery having a battery frame that is disposed under the cross member under a floor of the vehicle and extends in a front-rear direction of the vehicle on the inner side of the pair of side sills in a vehicle width direction; a reinforcing member that is housed in the hollow portion of each of the pair of side sills, has at least a portion configured with a closed cross-sectional structure, and is arranged in a region where the portion configured with the closed cross-sectional structure overlaps with the cross member in a side view from one side in the vehicle width direction; a fixing member that fixes the battery frame to the pair of side sills; Equipped with The fixing member is disposed so that a portion thereof penetrates the reinforcing member and fixes the battery frame to the side sill together with the reinforcing member. Vehicle undercarriage.

2. the reinforcing member includes a main body portion having a portion configured with the closed cross-sectional structure, and a bracket disposed below the main body portion, The fixing member is disposed so that a portion thereof penetrates into the bracket and fixes the bracket to the battery frame. The vehicle undercarriage according to claim 1 .

3. The fixing member is disposed so that a portion of the fixing member penetrates into the main body portion. The vehicle undercarriage according to claim 2.

4. The fixing member has a rod-shaped portion that penetrates into the main body portion, the main body portion has an opening having a size larger than a cross-sectional size of the rod shape at a portion into which the part of the fixing member penetrates; The vehicle undercarriage according to claim 3.

5. The side sill is fixed to the battery frame with a portion of an outer wall of the side sill sandwiched between the bracket and the battery frame. The vehicle undercarriage according to claim 2.

6. The main body is fixed to the side sill on at least one of the inner side and the outer side in the vehicle width direction. The vehicle undercarriage according to claim 2.

7. The bracket is fixed to the main body. The vehicle undercarriage according to claim 2.

8. The battery frame includes a portion having a closed cross-sectional structure in at least a part thereof, The fixing member fixes the portion of the battery frame having the closed cross-sectional structure to the side sill and the reinforcing member. The vehicle underbody structure according to any one of claims 1 to 7.

9. The fixing member is arranged to extend upward in the vertical direction of the vehicle from the portion of the battery frame having the closed cross-sectional structure toward the reinforcing member. The vehicle undercarriage according to claim 8.

10. Each of the pair of side sills includes a side sill outer disposed on an outer side in the vehicle width direction, and a side sill inner disposed on an inner side in the vehicle width direction and fixed to the side sill outer, The battery frame and the reinforcing member are fixed to the side sill inner by the fixing member. The vehicle underbody structure according to any one of claims 1 to 7.

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