TECHNICAL FIELD

The present invention relates to a vehicle body substructure.

The present application claims priority based on Japanese Patent Application No. 2017-100755 filed on May 22, 2017; Japanese Patent Application No. 2017-106655 filed on May 30, 2017; Japanese Patent Application No. 2017-106656 filed on May 30, 2017; and Japanese Patent Application No. 2017-110330 filed on Jun. 2, 2017, the contents of which are incorporated herein by reference.

BACKGROUND ART

As an example of vehicle body substructures, a structure in which a floor panel is laid between a side sill on the left side and a side sill on the right side, a floor cross-member is provided on an upper surface of the floor panel, and a battery pack is mounted below the floor panel is known. A battery is accommodated inside the battery pack. There is a need for the battery inside the battery pack to be protected from a load input laterally to a vehicle.

Therefore, the side sills are increased in height, and energy absorption members are provided inside the side sills. Moreover, the floor cross-member is provided toward the energy absorption member. Thus, the energy absorption member is crushed by an impact load input laterally to the vehicle, so that the impact load can be absorbed by the energy absorption member.

Accordingly, deformation of side walls of a battery case can be suppressed, so that the battery inside the battery pack (that is, an underfloor mounting component) can be protected (for example, refer to Patent Document 1).

In addition, as a substructure body of a vehicle, a structure in which a battery case accommodating a plurality of batteries is laid between left and right side sills of a vehicle body is known (for example, refer to Patent Document 2 and Patent Document 3).

In the substructure body of a vehicle disclosed in Patent Document 2, the battery case disposed below a floor panel is laid between the left and right side sills. A battery cross-member extending in a vehicle width direction is coupled to the inside of the battery case. The battery cross-member extends substantially in the vehicle width direction and is coupled to a circumferential wall or a bottom wall of the battery case. When an impact load is input laterally to the side sill, the battery cross-member functions to transmit the input load inward in the vehicle width direction while ensuring a space portion on the inner side in the vehicle width direction. The battery cross-member is formed to have a substantially uniform cross section in the vehicle width direction.

Incidentally, in vehicles in which a battery cross-member is laid inside a battery case, sometimes it is desirable that a recessed portion through which a member such as a distribution cable is inserted be provided in an upper portion of the battery cross-member. Patent Document 3 discloses a substructure body of a vehicle which can meet such a demand.

In the substructure body of a vehicle disclosed in Patent Document 3, a battery cross-member includes a lower member that is laid between left and right side walls of a battery case, and an upper member which is coupled to an upper portion of the lower member. The upper member is divided into two blocks in a central region in the vehicle width direction, and the two blocks are coupled to the upper portion of the lower member in a state where they are separated from each other in a traverse direction. Accordingly, a recessed portion through which a distribution cable or the like can be inserted is constituted between the two blocks of the upper member.

In addition, in the substructure body of a vehicle disclosed in Patent Document 3, the battery case disposed below a floor panel is laid between the left and right side sills. The battery cross-member extending in the vehicle width direction is coupled to the inside of the battery case. The battery cross-member has a longitudinally rectangular cross section extending substantially in the vehicle width direction and is coupled to a circumferential wall or a bottom wall of the battery case. When an impact load is input laterally to the side sill, the battery cross-member functions to transmit the input load inward in the vehicle width direction while ensuring a space portion on the inner side in the vehicle width direction.

In addition, in the substructure body of a vehicle disclosed in Patent Document 3, a vehicle body-side cross-member extending substantially in the vehicle width direction on the floor panel is disposed on an upper side of the battery cross-member. In the vehicle body-side cross-member, both end portions in the vehicle width direction are laid between the left and right side sills, and the central region in the vehicle width direction is connected to the battery cross-member provided below with a fastening member interposed therebetween. In addition, seatbelt anchors for supporting anchor belts of seatbelt devices are fixed to the vehicle body-side cross-member.

Moreover, as another example of vehicle body substructures, a structure in which energy absorption members are provided inside side sills, a battery pack is provided below a floor panel, and a battery cross-member is provided inside the battery pack is known. A battery is accommodated in the battery pack.

According to the vehicle body substructure, an impact load input laterally to a vehicle can be absorbed by the energy absorption member, and the battery cross-member can withstand the remaining load. Accordingly, the battery pack (that is, the battery) can be protected from an impact load input laterally to the vehicle.

Incidentally, in a sedan which is a type of vehicle, lower end portions of side sills are disposed substantially at the same height as the minimum ground clearance dimension. Therefore, a lower surface (that is, a bottom portion) of the battery pack is disposed substantially at the same ground clearance dimension as that of the lower end portions of the side sills.

Since the lower surface of the battery pack is disposed substantially at the same ground clearance dimension as that of the lower end portions of the side sills, the battery pack can be concealed such that it cannot be seen from the outside of the vehicle.

In addition, since the lower surface of the battery pack is disposed substantially at the same ground clearance dimension as that of the lower end portions of the side sills, an impact load input laterally to the vehicle is absorbed by the energy absorption member inside the side sill, and then the battery cross-member can withstand the remaining load. Accordingly, the battery pack (that is, the battery) can be protected from an impact load input laterally to the vehicle (for example, refer to Patent Document 1).

RELATED ART DOCUMENT

Patent Document

Patent Document 1: Specification of U.S. Pat. No. 8,702,161Patent Document 2: Japanese Patent No. 5880086Patent Document 3: Specification of U.S. Pat. No. 8,336,658

SUMMARY

Problems to be Solved by the Invention

However, in a vehicle body substructure of Patent Document 1, side sills are increased in height. Thus, upper portions of the side sills are positioned above a floor panel. Therefore, the side sills become a hindrance when an occupant boards and alights, so that it is difficult to favorably ensure boarding/alighting properties for an occupant.

In addition, since the side sills are increased in height, reduction of the weights of the side sills (that is, the weight of the vehicle body) is impeded.

Therefore, an object of the present invention is to provide a vehicle body substructure in which an underfloor mounting component can be protected from an impact load input laterally to a vehicle in a state where boarding/alighting properties for an occupant are ensured favorably.

In addition, in a substructure body disclosed in Patent Document 3, since an upper member and a lower member are constituted of thick metal extrusion molded articles, a sufficient rigidity for receiving a lateral impact load to a vehicle body can be ensured in a relatively easy manner. However, when a main portion of a battery cross-member is constituted of an extrusion molded article as in the substructure body disclosed in Patent Document 3, there is a concern that the manufacturing cost may increase.

Therefore, another object of the present invention is to provide a substructure body of a vehicle in which while a recessed portion allowing communication in a front-rear direction is constituted substantially in a central region of a battery cross-member in a vehicle width direction, a sufficient rigidity in the vehicle width direction can be ensured without causing increase in manufacturing cost.

In the substructure body of a vehicle disclosed in Patent Document 3, the battery cross-member is formed to have a longitudinally rectangular cross section, and a lower end thereof is welded and fixed to an upper surface of a bottom wall of a battery case. Therefore, when a significant load in the front-rear direction is input to a vehicle body-side cross-member through a seatbelt anchor and the load is transmitted to the upper portion of the battery cross-member via a fastening member, there is a concern that the battery cross-member may fall forward or rearward due to a moment acting on the battery cross-member.

Therefore, another object of the present invention is to provide a substructure body of a vehicle in which falling of the battery cross-member in the front-rear direction is suppressed when a load in the front-rear direction is input from a vehicle body-side cross-member to the battery cross-member, and a high support rigidity of the vehicle body-side cross-member can be maintained.

Incidentally, a sport utility vehicle (SUV) is known as a type of vehicle. In an SUV, side sills are provided at positions higher than those of sedan-type vehicles. Thus, when a battery pack is mounted in an SUV, a lower surface of the battery pack can be disposed below the side sills. Since the lower surface of the battery pack is disposed below the side sills, the battery pack can be increased in size.

However, when the lower surface of the battery pack is disposed below the side sills, a lower portion of the battery cross-member is provided below the side sills. Thus, an impact load input laterally to the vehicle is unlikely to be transmitted to the lower portion of the battery cross-member. Accordingly, it is difficult for the lower portion of the battery cross-member to withstand the impact load, and therefore a device for protecting the battery pack (that is, an underfloor mounting component) from an impact load is required.

Therefore, another object of the present invention is to provide a vehicle body substructure in which an underfloor mounting component can be protected from an impact load input laterally to the vehicle in a state where the lower surface of the battery pack is disposed below the side sills.

Means for Solving the Problem

As means for solving the foregoing problems, aspects of the present invention have the following constitutions.

(1) A vehicle body substructure according to an aspect of the present invention includes side sill load transmitting members that are provided inside each of side sills, a floor cross-member that is provided on one of an upper surface and a lower surface of a floor panel laid between the side sills and has extending portions extending toward upper portions of the side sill load transmitting members, an underfloor mounting component that is provided below the floor panel and includes an underfloor cross-member, underfloor frames that are attached to lower portions of the underfloor mounting component and the side sills, and underfloor load transmitting members that are provided in the underfloor frames and face the underfloor cross-member. The underfloor load transmitting member has an upper half portion which faces a lower portion of the side sill load transmitting member, and a lower half portion which is fixed to a part of the underfloor frame attached to a lower portion of the side sill.

In the vehicle body substructure according to (1) of the present invention, the side sill load transmitting members are provided inside each of the side sills. The extending portions of the floor cross-member extend toward the upper portions of the side sill load transmitting members. In addition, the underfloor load transmitting members face the underfloor cross-member. The upper half portion of the underfloor load transmitting member faces the lower portion of the side sill load transmitting member. Moreover, the lower half portion of the underfloor load transmitting member is connected to the lower portion of the side sill with the underfloor frame interposed therebetween.

Thus, when an impact load is input laterally to a vehicle, a part of the impact load is transferred to the floor cross-member as a first load path via the upper portion of the side sill load transmitting member. In addition, a part of the remaining impact load is transferred to the underfloor cross-member as a second load path via the lower portion of the side sill load transmitting member and the upper half portion of the underfloor load transmitting member.

Moreover, the remaining impact load is transferred to the underfloor cross-member as a third load path via the lower portion of the side sill, the underfloor frame, and the lower half portion of the underfloor load transmitting member.

In this manner, an impact load input laterally to the vehicle can be dispersed and transmitted via transmission paths such as the first load path, the second load path, and the third load path. Thus, the floor cross-member and the underfloor cross-member can withstand an impact load. Accordingly, falling deformation of side walls of the underfloor mounting component can be suppressed, and the underfloor mounting component can be protected from an impact load.

In addition, since an impact load input laterally to the vehicle is dispersed and transmitted through the first to third load paths, there is no need to increase the heights of the side sills and provide the side sill load transmitting members inside the side sills. Accordingly, the side sills do not become a hindrance when an occupant boards and alights, so that boarding/alighting properties for an occupant can be ensured favorably.

In addition, since there is no need to increase the heights of the side sills, increase in weight of the side sills (that is, weight of the vehicle body) can be suppressed.

(2) In the vehicle body substructure according to (1), the underfloor cross-member may have left and right side portion members which are disposed on left and right sides in a vehicle width direction, and a central member which is disposed substantially at a center in the vehicle width direction. Cross sections of the left and right side portion members and the central member may be formed to be a substantially hat-shaped cross section. An upper surface of the central member may be formed lower than upper surfaces of the left and right side portion members. The upper surface of the central member and end portions of the left and right side portion members on inner sides in the vehicle width direction may constitute a recessed portion which allows communication in a front-rear direction of a vehicle body. Each of the left and right side portion members may be coupled to the floor cross-member thereabove and may be coupled to the central member with respect to the floor cross-member in a vicinity of a part below a coupling portion.

In the vehicle body substructure according to (2) of the present invention, a battery cross-member is constituted of the left and right side portion members and the central member as main elements having relatively simple shapes. Therefore, the left and right side portion members and the central member can be easily formed of press-formed articles or the like. In addition, since the upper surface of the central member and the end portions of the left and right side portion members constitute the recessed portion, the recessed portion can be utilized as an insertion groove for a distribution cable or the like.

In addition, since the left and right side portion members are coupled to the central member in the vicinity of a part below the coupling portion with respect to the floor cross-member, when an impact load is input laterally to the side portion member through the side sill of the vehicle body, the input load can be dispersed to and supported by the floor cross-member and the central member. Therefore, when this constitution is employed, while a battery cross-member which can be manufactured at low cost is employed, bending of the battery cross-member in a central region can be suppressed when an impact load is input from the side sills.

(3) In the vehicle body substructure according to (1), the underfloor cross-member may be formed to have an inverted T-shaped cross section having a member main body portion which stands upright and of which an upper portion is coupled to the floor cross-member using a fastening member, a forward protruding seat which protrudes forward from a lower edge of the member main body portion, and a rearward protruding seat which protrudes rearward from the lower edge of the member main body portion. The forward protruding seat and the rearward protruding seat may be coupled to a bottom wall of a battery case.

In the vehicle body substructure according to (3) of the present invention, when a load in the front-rear direction is input to a vehicle body-side cross-member, the load is input to an upper portion of the member main body portion of the battery cross-member via the fastening member. Accordingly, a moment in a direction tilting forward and rearward acts on the member main body portion. Meanwhile, the forward protruding seat and the rearward protruding seat extend forward and rearward in the member main body portion, and the protruding seats are coupled to the bottom wall of the battery case. Therefore, falling of the member main body is suppressed by the forward protruding seat and the rearward protruding seat. As a result, the vehicle body-side cross-member is supported with a high rigidity via the member main body and the fastening member.

(4) The vehicle body substructure according to (1) may further include frame portions that are disposed on outer sides of the underfloor mounting component and face inner corner portions. The underfloor mounting component may include the underfloor cross-member which faces the frame portions. The frame portion may include an engagement portion which confronts the inner corner portion, and an inclination portion which extends in a manner inclining upward from a lower surface side of the underfloor mounting component toward a lower end portion of a side sill flange such that an imaginary extension line intersects the side sill flange.

In the vehicle body substructure according to (4) of the present invention, the side sill flange of the side sill extends downward from the outer side of the inner corner portion in the vehicle width direction. In addition, the inclination portion of the frame portion extends in a manner inclining upward from the lower surface side of the underfloor mounting component toward the lower end portion of the side sill flange, and the imaginary extension line of the inclination portion intersects the side sill flange. Thus, the inclination portion can be concealed by the side sill flange such that it is unlikely to be viewed from the outside of the vehicle. Accordingly, a large-sized underfloor mounting component in which the lower surface of the underfloor mounting component is disposed below the side sills can be mounted in a vehicle without affecting the appearance of the vehicle.

In addition, since the inclination portion is formed in the frame portion, a part of an impact load input laterally to the side sill of the vehicle can be transferred to a lower portion of the underfloor cross-member as a so-called offset load via the frame portion.

Moreover, the upper portion of the underfloor cross-member faces the side sills. That is, a part of an impact load input laterally to the side sill of the vehicle can be transferred to the upper portion of the underfloor cross-member.

Thus, an impact load input laterally to the side sill of the vehicle can be dispersed and transferred to the upper portion and the lower portion of the underfloor cross-member. Accordingly, the underfloor cross-member can withstand an impact load. As a result, a large-sized underfloor mounting component in which the lower surface of the underfloor mounting component is disposed below the side sills can be protected from an impact load.

(5) In the vehicle body substructure according to (1), the floor cross-member may be provided on the upper surface of the floor panel. The extending portion may extend with a downward slope to the side sill. A gusset laid at an interval from the extending portion may be provided between the lower surface of the floor panel and an inside wall of the side sill.

In the vehicle body substructure according to (5) of the present invention, the extending portion of the floor cross-member extends with a downward slope to the side sill. Moreover, the gusset is laid between the lower surface of the floor panel and the inside wall of the side sill, and the gusset is provided at an interval from the extending portion. Thus, substantially the same cross section as a cross section of the floor cross-member can be formed by the extending portion and the gusset. In addition, a cross section formed by the extending portion and the gusset can be a cross section having substantially the same size as that of the floor cross-member.

Accordingly, an impact load input laterally to the vehicle can be transferred favorably to the floor cross-member by the extending portion and the gusset, and the first load path can be ensured.

Moreover, since the floor cross-member is provided on the upper surface of the floor panel, the floor cross-member can be removed from below the floor panel. Accordingly, the volume of a mounting component provided below the floor panel can be increased.

(6) In the vehicle body substructure according to (1) or (5), the upper half portion of the underfloor load transmitting member may be disposed at a same height as the side sill load transmitting member. The lower half portion of the underfloor load transmitting member may be disposed at a same height as a part of the underfloor frame attached to the lower portion of the side sill. The upper half portion and the lower half portion may be fixed to the underfloor frame.

In the vehicle body substructure according to (6) of the present invention, the upper half portion of the underfloor load transmitting member is fixed, and the upper half portion is disposed at the same height as the side sill load transmitting member. Thus, the second load path transmitting an impact load from the side sill load transmitting member to the upper half portion of the underfloor load transmitting member can be ensured.

In addition, the lower half portion of the underfloor load transmitting member is fixed, and the lower half portion is disposed at the same height as a part of the underfloor frame attached to the lower portion of the side sill. Thus, the third load path transmitting an impact load from a part of the underfloor frame attached to the lower portion of the side sill to the lower half portion of the underfloor load transmitting member can be ensured.

Accordingly, an impact load input laterally to the vehicle can be dispersed reliably to the underfloor cross-member via the second load path and the third load path.

(7) In the vehicle body substructure according to any one of (1), (5), and (6), the underfloor frame may have a frame inside wall portion which faces the underfloor mounting component, and a frame extension portion which extends from the frame inside wall portion along a bottom portion of the underfloor mounting component. The underfloor cross-member may be disposed inside the underfloor mounting component. The underfloor cross-member may be formed to have a strut portion which rises from the bottom portion of the underfloor mounting component and of which end portions facing the upper half portion of the underfloor load transmitting member are fixed to side walls of the underfloor mounting component, and a seat portion which protrudes along the bottom portion from the strut portion and is fixed to the frame extension portion with the bottom portion interposed therebetween.

In the vehicle body substructure according to (7) of the present invention, the end portions of the strut portion of the underfloor cross-member are fixed to the side walls of the underfloor mounting component. Thus, the second load path transmitting an impact load from the upper half portion of the underfloor load transmitting member to the strut portion of the underfloor cross-member can be ensured.

In addition, the seat portion of the underfloor cross-member is fixed to the frame extension portion with the bottom portion interposed therebetween. Thus, the third load path transmitting an impact load from the frame extension portion (that is, the underfloor frame) to the seat portion of the underfloor cross-member can be ensured. Accordingly, an impact load input laterally to the vehicle can be dispersed reliably to the underfloor cross-member via the second load path and the third load path.

(8) In the vehicle body substructure according to (7), the underfloor mounting component may include traverse members which extend along the seat portion in a state of being fixed to an outer surface of the bottom portion and have a bead projecting toward the bottom portion. The seat portion may be fixed in a state of overlapping the bottom portion and the traverse members of the underfloor mounting component.

In the vehicle body substructure according to (8) of the present invention, the seat portion of the underfloor cross-member is fixed in a state of overlapping the bottom portion of the underfloor mounting component and the traverse member. In addition, the bead is formed in the traverse member. A cross-sectional strength of the traverse member can be enhanced by the bead. Thus, the seat portion of the underfloor cross-member can be reinforced firmly by the traverse member. Accordingly, the efficiency of transmitting an impact load in the third load path can be improved.

(9) In the vehicle body substructure according to (8), the underfloor frame may have an attachment apex portion which is attached to the lower portion of the side sill, an attachment outside wall portion which extends downward from the attachment apex portion, an attachment bottom portion which extends in a same plane as the frame extension portion from the attachment outside wall portion to the frame extension portion, and a connection portion which is offset downward from the attachment bottom portion and is fixed to the frame extension portion. The underfloor frame may be formed to have a U-shaped cross section by the attachment apex portion, the attachment outside wall portion, and the attachment bottom portion.

In the vehicle body substructure according to (9) of the present invention, the attachment bottom portion of the underfloor frame extends in the same plane as the frame extension portion. Thus, the attachment bottom portion of the underfloor frame extends linearly with the extension portion. Accordingly, an impact load can be transmitted linearly from the attachment bottom portion to the frame extension portion, so that transmission efficiency of the third load path can be improved.

(10) In the vehicle body substructure according to (8) or (9), the underfloor frames may be provided in the left and right side walls of the underfloor mounting component. The seat portion may be provided between the left and right underfloor frames in a connected state in the vehicle width direction. The traverse members may be provided to extend in the vehicle width direction on the left and right sides at an interval from the center in the vehicle width direction. A longitudinal member which is disposed between the traverse members on the left and right sides, extends in the front-rear direction of the vehicle body, and is fixed to the bottom portion of the underfloor mounting component may be provided.

In the vehicle body substructure according to (10) of the present invention, the bottom portion of the underfloor mounting component includes the seat portion (that is, the underfloor cross-member) and the traverse members. Accordingly, the seat portion (underfloor cross-member) and the traverse members can withstand an impact load input laterally to the vehicle.

In addition, the bottom portion of the underfloor mounting component includes the longitudinal member. Accordingly, the longitudinal member can withstand an impact load input in the front-rear direction of the vehicle.

Moreover, since the bottom portion of the underfloor mounting component includes the traverse members and the longitudinal member, the strength of the underfloor mounting component can be enhanced. Accordingly, the underfloor mounting component can be increased in size. For example, when a battery pack is applied as the underfloor mounting component, the volume for accommodating a battery can be increased by increasing the size of the battery pack.

(11) In the vehicle body substructure according to (2), a pair of partition wall members individually fixed to at least three surfaces such as a front wall, an upper wall, and a rear wall of the substantially hat-shaped cross section of the side portion member may be provided in the left and right side portion members. The pair of partition wall members may be provided at positions in front of and behind the coupling portion with respect to the floor cross-member in an extending direction of the side portion member.

In the vehicle body substructure according to (11) of the present invention, since cross sections at the positions in front of and behind the coupling portion with respect to the floor cross-member of each of the side portion members are reinforced firmly by the partition wall member, when an impact load is input laterally to the side portion member of the vehicle body, crushing of a cross section of the side portion member in the vicinity of the coupling portion with respect to the floor cross-member can be suppressed.

(12) In the vehicle body substructure according to (11), the central member may be coupled to the left and right side portion members in regions below the partition wall members.

In the vehicle body substructure according to (12) of the present invention, since a closed cross section constituted by the central member and the left and right side portion members coupled to each other is reinforced internally by each of the partition wall members, crushing of a cross section of the side portion member can be suppressed more effectively.

(13) In the vehicle body substructure according to (12), a stud bolt fastened to the upper wall of the side portion member may be used for the coupling portions of the left and right side portion members with respect to the floor cross-member. The pair of partition wall members may be provided in front of and behind a protruding position of the stud bolt in the extending direction of the side portion member.

In the vehicle body substructure according to (13) of the present invention, the floor cross-member and the left and right side portion members separated from each other in an up-down direction can be easily coupled to each other using the stud bolt. In addition, crushing of a cross section in fastening portions of the stud bolts of the left and right side portion members is suppressed by the closed cross section formed by the central member and the side portion members, and the partition wall members.

(14) In the vehicle body substructure according to (13), a battery and the underfloor cross-member may be disposed inside the battery case. The battery case may include a case main body which has an open upper side, and a case cover which blocks an opening of the case main body. The stud bolt may have a screw portion which protrudes upward from the case cover and is fastened and fixed to the floor cross-member side due to the screw portion. A body portion of the stud bolt may be held in a penetration hole of the case cover with an elastic seal member interposed therebetween.

In the vehicle body substructure according to (14) of the present invention, since the body portion of the stud bolt is held in the penetration hole of the case cover with the elastic seal member interposed therebetween, the position and the direction of the screw portion protruding upward from the case cover can be adjusted finely at the time of work of fastening the floor cross-member to the stud bolt. Therefore, when this constitution is employed, workability of fastening the floor cross-member to the stud bolt becomes favorable. In addition, infiltration of water into the battery case through the penetration hole of the case cover can be suppressed by the elastic seal member.

(15) In the vehicle body substructure according to (14), a bracket having an insertion hole may be attached to an inside of the floor cross-member, in which a work hole facing the insertion hole is provided in an upper wall. A nut may be fastened and fixed to the screw portion of the stud bolt protruding upward from the insertion hole, through the work hole.

In the vehicle body substructure according to (15) of the present invention, the rigidity of the floor cross-member is enhanced by the bracket. In addition, since the work hole of the bracket facing the insertion hole is provided in the floor cross-member, work of tightening the nut to the screw portion of the stud bolt can be performed easily through the work hole.

(16) In the vehicle body substructure according to any one of (2) and (11) to (15), auxiliary partition wall members substantially blocking gaps between the lower surfaces of the side portion members and the upper surface of the central member may be coupled to end edges of the left and right side portion members on the inner sides in the vehicle width direction and the central member.

In the vehicle body substructure according to (16) of the present invention, crushing of a cross section at the end edge of each of the left and right side portion members on the inner sides in the vehicle width direction can be suppressed by the auxiliary partition wall member, so that the rigidity of the battery cross-member can be further enhanced. In addition, since the gap between the end edge of each of the left and right side portion members on the inner sides in the vehicle width direction and the central member is substantially blocked by the auxiliary partition wall member, entry of a foreign substance into the side portion member from the end portion of each of the left and right side portion members on the inner sides in the vehicle width direction can be suppressed.

(17) In the vehicle body substructure according to any one of (2) and (11) to (16), the underfloor cross-member may include a forward protruding seat which protrudes forward from a lower edge of a front wall, and a rearward protruding seat which protrudes rearward from a lower edge of a rear wall. The forward protruding seat and the rearward protruding seat may be disposed on an upper surface side of a bottom wall of a battery case, and a lower surface reinforcement member may be disposed on a lower surface side of the bottom wall. The forward protruding seat and the rearward protruding seat may be coupled to the lower surface reinforcement member in a state where the bottom wall is sandwiched therebetween.

In the vehicle body substructure according to (17) of the present invention, since the forward protruding seat and the rearward protruding seat of the battery cross-member are coupled to the lower surface reinforcement member in a state where the bottom wall of the battery case is sandwiched therebetween, front and rear lower ends of the battery cross-member can be supported by the battery case with a high rigidity.

(18) In the vehicle body substructure according to (17), the lower surface reinforcement member may be coupled to the lower surface of the bottom wall in a manner extending substantially in the vehicle width direction. An alternative lower surface reinforcement member extending substantially in the front-rear direction of the vehicle body may be also coupled to the lower surface of the bottom wall.

In the vehicle body substructure according to (18) of the present invention, since the bottom wall of the battery case is reinforced by the lower surface reinforcement member extending substantially in the vehicle width direction and the alternative lower surface reinforcement member extending substantially in the front-rear direction of the vehicle body, the rigidity of the bottom wall of the battery case in its entirety can be enhanced.

(19) The vehicle body substructure according to any one of (2) and (11) to (18) may further include a load transmitting plate that is laid across the upper surfaces of the left and right side portion members.

In the vehicle body substructure according to (19) of the present invention, the bending rigidity in the central region of the battery cross-member in the vehicle width direction can be enhanced efficiently by the load transmitting plate. In addition, since the bending rigidity of the battery cross-member can be enhanced efficiently by only laying the load transmitting plate across the upper surfaces of the left and right side portion members, an increase in manufacturing cost for reinforcement of the members can be suppressed.

(20) In the vehicle body substructure according to (3), the forward protruding seat and the rearward protruding seat may be disposed on an upper surface side of the bottom wall of the battery case. A lower surface reinforcement member may be disposed on a lower surface side of the bottom wall. The forward protruding seat and the rearward protruding seat may be coupled to the lower surface reinforcement member in a state where the bottom wall is sandwiched therebetween.

In the vehicle body substructure according to (20) of the present invention, since the forward protruding seat and the rearward protruding seat of the battery cross-member are integrated with the bottom wall of the battery case together with the lower surface reinforcement member, forward and rearward falling of the member main body portion of the battery cross-member can be suppressed more firmly. In addition, when this constitution is employed, members to be coupled to each other can be constituted of press-formed articles which can be manufactured at low cost, and the members can be welded and fixed to each other.

(21) In the vehicle body substructure according to (20), the lower surface reinforcement member may be constituted of a plate-shaped member of which a substantially wave-shaped cross section extends substantially in the vehicle width direction.

In the vehicle body substructure according to (21) of the present invention, since a substantially wave-shaped cross section of the plate-shaped member serving as the lower surface reinforcement member extends substantially in the vehicle width direction on the lower surface side of the bottom wall of the battery case, the rigidity of the bottom wall of the battery case can be enhanced efficiently by the plate-shaped lower surface reinforcement member.

(22) In the vehicle body substructure according to (20), the battery case may have case side walls which rise upward from left and right end portions of the bottom wall. A case frame extending substantially in the front-rear direction of the vehicle body may be coupled to an outer side of the case side wall. The case frame may have an extension piece which is disposed on the lower surface of the bottom wall of the battery case and constitutes the lower surface reinforcement member. The forward protruding seat and the rearward protruding seat may be coupled to the extension piece in a state where the bottom wall is sandwiched therebetween.

In the vehicle body substructure according to (22) of the present invention, the extension piece provided in the case frame is disposed on the lower surface of the bottom wall of the battery case, and the forward protruding seat and the rearward protruding seat of the battery cross-member are integrated with the bottom wall of the battery case and the extension piece. Accordingly, forward and rearward falling of the member main body portion of the battery cross-member is suppressed more firmly.

(23) In the vehicle body substructure according to any one of (3) and (20) to (22), the member main body portion of the underfloor cross-member may have an upper wall, a front wall which extends downward from a front portion of the upper wall, and a rear wall which extends downward from a rear portion of the upper wall. A partition wall member restricting three surfaces such as the upper wall, the front wall, and the rear wall of the member main body portion may be coupled in a vicinity of a fixing portion of the fastening member of the member main body portion.

In the vehicle body substructure according to (23) of the present invention, since the cross-sectional rigidity in the vicinity of the fixing portion of the fastening member of the member main body portion is enhanced by the partition wall member, cross-sectional deformation in the vicinity of the fixing portion of the fastening member can be suppressed efficiently. Therefore, even when the wall thickness of the member main body portion has to be reduced for weight reduction, tilting or sinking of the fastening member can be suppressed, and the floor cross-member can be supported by the battery cross-member with a high rigidity.

(24) In the vehicle body substructure according to any one of (3) and (20) to (23), the floor panel may be disposed above the battery case. The floor cross-member may include a cross-plate which has a substantially hat-shaped cross section, is joined to the upper surface of the floor panel, forms a closed cross section extending substantially in the vehicle width direction between the cross-plate and the floor panel, and has both end portions in the vehicle width direction laid between the pair of side sills, and a gusset inclination portion which has a substantially hat-shaped cross section, is laid between a lower surface in an end portion region of the floor panel in the vehicle width direction and a side surface of the side sill, and forms a closed cross section extending substantially in the vehicle width direction between the gusset inclination portion and the floor panel. An end portion region of the gusset inclination portion in the vehicle width direction and the gusset inclination portion may be formed to incline downward to a side outward in the vehicle width direction. A bracket which also serves as a cross section reinforcing portion may be internally attached in a region closer to a center of the cross-plate in the vehicle width direction. The bracket may be coupled to the member main body portion of the underfloor cross-member using the fastening member.

In the vehicle body substructure according to (24) of the present invention, since the end portion region of the cross-plate in the vehicle width direction and a gusset plate are formed to incline downward to a side outward in the vehicle width direction, a closed cross section of the central region formed by the floor panel and the cross-plate is connected to an inclined closed cross section in the end portion region formed by the cross-plate and the gusset plate. Therefore, while the central region of the vehicle body-side cross-member has a shape lifted upward with respect to the side sills, the left and right side sills can be connected to each other through a closed cross section of the vehicle body-side cross-member connected in a substantially uniform manner. In addition, when this constitution is employed, since the central region of the vehicle body-side cross-member has a shape lifted upward with respect to the side sills, the battery case disposed below the central region of the vehicle body-side cross-member can be positioned on an upper side. Therefore, a ground clearance below the battery case can be ensured easily. In addition, a cross section in the central region of the cross-plate is reinforced by the bracket which also serves as the cross section reinforcing portion, and the bracket is coupled to the battery cross-member using the fastening member. Therefore, when a load is input to the vehicle body-side cross-member, the input load can be supported by the battery cross-member in a state where cross-sectional deformation of the cross-plate is suppressed.

(25) In the vehicle body substructure according to (24), a battery and the underfloor cross-member may be disposed inside the battery case. The battery case may include a case main body which has an open upper side, and a case cover which blocks an opening of the case main body. The fastening member may be a stud bolt of which both end portions are fastened to the bracket and the underfloor cross-member. A body portion of the stud bolt may be held in a penetration hole of the case cover with an elastic seal member interposed therebetween.

In the vehicle body substructure according to (25) of the present invention, since the body portion of the stud bolt is held in the penetration hole of the case cover with the elastic seal member interposed therebetween, when the stud bolt and the vehicle body-side cross-member are fastened and fixed to each other, the position and the direction of the screw portion protruding upward from the case cover can be adjusted finely. Therefore, when this constitution is employed, workability of fastening the vehicle body-side cross-member to the stud bolt becomes favorable. In addition, since the penetration hole of the case cover is blocked by the elastic seal member, infiltration of water into the battery case through the penetration hole can be prevented. In this case, vibration of the case cover can be further suppressed by the elastic seal member.

In addition, when the upper surface of the elastic seal member abuts the lower surface of a surrounding area of the penetration hole of the floor panel, infiltration of water into a vehicle cabin through the penetration hole of the floor panel can also be prevented. Moreover, in this case, vibration of the floor panel can be suppressed by the elastic seal member.

(26) In the vehicle body substructure according to (22), an attachment frame connecting the case frame to a lower surface of the side sill may be coupled to the case frame. A frame extension piece overlapping a lower surface of the extension piece of the case frame may extend in the attachment frame. The frame extension piece may be coupled to the bottom wall of the battery case together with the extension piece.

In the vehicle body substructure according to (26) of the present invention, since the frame extension piece of the attachment frame and an extension wall of the case frame are coupled to the bottom wall of the battery case in a three-layered manner, the attachment frame and the case frame can be coupled to each other more firmly, and the rigidity of the bottom wall of the battery case can also be enhanced.

(27) In the vehicle body substructure according to any one of (3) and (20) to (26), the member main body portion of the underfloor cross-member may have an upper wall, a front wall which extends downward from a front portion of the upper wall, and a rear wall which extends downward from a rear portion of the upper wall. A reinforcement plate which has a substantially U-shaped cross section and is joined to the upper wall, the front wall, and the rear wall may be disposed inside the member main body portion.

In the vehicle body substructure according to (27) of the present invention, the rigidity of the member main body portion to which the fastening member is fixed can be enhanced easily with a simple constitution. In addition, the reinforcement plate can be formed of a press-formed article which can be manufactured at low cost. Therefore, the product cost can be reduced.

(28) In the vehicle body substructure according to any one of (3) and (20) to (27), the forward protruding seat and the rearward protruding seat may include a pedestal portion of which a lower surface projecting upward communicates with an internal space of the member main body portion and of which an upper surface is substantially flat.

In the vehicle body substructure according to (28) of the present invention, the upper surface of each of the pedestal portions provided in the forward protruding seat and the rearward protruding seat can be utilized as a battery support portion or the like. In addition, since the lower surface sides of the forward protruding seat and the rearward protruding seat can communicate widely with the internal space of the member main body portion due to the pedestal portions standing upright, an electrodeposition coating solution for rust prevention can be applied easily everywhere inside the battery cross-member at the time of manufacturing.

(29) In the vehicle body substructure according to (4), the frame portion may be provided in an outer circumferential wall of the underfloor mounting component and may be formed to have an L-shaped closed cross section by the engagement portion and the inclination portion.

In the vehicle body substructure according to (29) of the present invention, the engagement portion confronts the inner corner portion. Moreover, the frame portion is formed to have an L-shaped closed cross section by the engagement portion and the inclination portion. Thus, the engagement portion is formed firmly in the frame portion. That is, the inner corner portion (that is, the side sill) can be received reliably by the frame portion in which the engagement portion is formed. Accordingly, an impact load input to the side sill can be transferred reliably to the underfloor cross-member via the frame portion. As a result, the underfloor cross-member can withstand the transferred impact load.

(30) In the vehicle body substructure according to (4) or (29), the side sill may include a side sill outer on the outer side in the vehicle width direction, a side sill inner which is joined to the side sill outer from the inner side in the vehicle width direction and forms a closed cross section together with the side sill outer, and a first energy absorption member which is disposed in the closed cross section and is attached to the side sill outer.

In the vehicle body substructure according to (30) of the present invention, the first energy absorption member is attached to the side sill outer. Thus, the degree of freedom of the shape of the side sill inner can be enhanced, so that the inner corner portion can be formed easily in the side sill inner. Since this inner corner portion is formed to have a right-angled shape, when an impact load is input laterally to the vehicle, the inner corner portion can be engaged favorably with the engagement portion.

Accordingly, a part of an impact load input laterally to the side sill of the vehicle can be transferred reliably to the lower portion of the underfloor cross-member as a so-called offset load via the frame portion.

(31) In the vehicle body substructure according to any one of (4), (29), and (30), the frame portion may include a second energy absorption member disposed therein.

In the vehicle body substructure according to (31) of the present invention, the second energy absorption member is included inside the frame portion. Thus, the second energy absorption member can be crushed by an impact load input laterally to the vehicle. Since the second energy absorption member is crushed by an impact load, the inner corner portion of the side sill can be engaged favorably with the frame portion.

Accordingly, a part of an impact load input laterally to the side sill of the vehicle can be transferred more reliably to the lower portion of the underfloor cross-member as a so-called offset load via the frame portion.

(32) In the vehicle body substructure according to any one of (4) and (29) to (31), an upper portion of the underfloor cross-member may be disposed to confront a central portion of the side sill in an up-down direction.

In the vehicle body substructure according to (32) of the present invention, the upper portion of the underfloor cross-member faces the central portion of the side sill. Accordingly, a part of an impact load input laterally to the side sill of the vehicle can be transferred to the upper portion of the underfloor cross-member as a so-called horizontal load.

Thus, an impact load input laterally to the side sill of the vehicle can be dispersed and transferred to the upper portion and the lower portion of the underfloor cross-member. Accordingly, the underfloor cross-member can withstand an impact load.

(33) In the vehicle body substructure according to any one of (4) and (29) to (32), the underfloor cross-member may include a fragile portion which is formed in an outer region on the outer side in the vehicle width direction, and a firm portion which is formed in an inner region on the inner side in the vehicle width direction.

In the vehicle body substructure according to (33) of the present invention, the fragile portion is formed in the outer region of the underfloor cross-member. Thus, an impact load input laterally to the vehicle can be absorbed by crushing the fragile portion.

Meanwhile, the firm portion is formed in the inner region of the underfloor cross-member. Thus, the firm portion can withstand a load after being absorbed by the fragile portion.

Accordingly, the floor panel can be divided into an energy absorption region on the outer side in the vehicle width direction and a protection region on the inner side in the vehicle width direction.

(34) In the vehicle body substructure according to any one of (4) and (29) to (33), the underfloor cross-member may be formed to have a hollow shape, be provided at a center in an up-down direction, and include a partitioning wall which vertically partitions the underfloor cross-member.

In the vehicle body substructure according to (34) of the present invention, the hollow underfloor cross-member is vertically partitioned by the partitioning wall. The underfloor cross-member can be divided into a cross-member upper portion and a cross-member lower portion by the partitioning wall.

Thus, a part of an impact load input laterally to the side sill of the vehicle can be transferred to the cross-member upper portion as a so-called horizontal load. In addition, a part of an impact load input laterally to the side sill of the vehicle can be transferred to the cross-member lower portion as a so-called offset load.

In this manner, a part of an impact load input laterally to the side sill of the vehicle can be transmitted in a manner divided into two paths such as the cross-member upper portion and the cross-member lower portion. As a result, the cross-member upper portion and the cross-member lower portion can favorably withstand a part of the impact load.

(35) The vehicle body substructure according to any one of (4) and (29) to (34) may further include a first floor cross-member and a second floor cross-member that extend in the vehicle width direction along the upper surface of the floor panel at an interval in a front-rear direction of a vehicle body. The first floor cross-member and the second floor cross-member may be formed to have a hat-shaped cross section by an apex portion, a pair of wall portions, a front flange, and a rear flange. The front flange and the rear flange may be joined to the upper surface of the floor panel. A seat may be supported by the first floor cross-member and the second floor cross-member. The first floor cross-member may have a first recessed portion which is recessed upward in a wall portion facing the second floor cross-member. The second floor cross-member may have a second recessed portion which is recessed upward in a wall portion facing the first floor cross-member. The floor panel may have a projection portion which projects upward along the first recessed portion and the second recessed portion.

In the vehicle body substructure according to (35) of the present invention, the seat is supported by the first floor cross-member and the second floor cross-member. That is, the first floor cross-member and the second floor cross-member is reinforced by the seat. Thus, the first recessed portion and the second recessed portion can be formed in a state where the strengths of the first floor cross-member and the second floor cross-member are ensured.

Moreover, the projection portion of the floor panel projects upward along the first recessed portion or the second recessed portion. Thus, a significant space can be ensured below the floor panel, so that the volume of the underfloor mounting component to be disposed below the floor panel can be increased.

Here, the projection portion of the floor panel is formed between the first floor cross-member and the second floor cross-member. Thus, the projection portion is positioned below the seat. For example, the projection portion is disposed on the rear side of the vehicle body with respect to feet (a part around a place where feet of an occupant are placed) of an occupant being seated in the seat. Accordingly, the projection portion can be prevented from becoming a hindrance when an occupant being seated in the seat places his/her feet.

(36) In the vehicle body substructure according to (35), the underfloor cross-member may be connected to the floor panel below the first floor cross-member and the second floor cross-member.

In the vehicle body substructure according to (36) of the present invention, the underfloor cross-member is connected to the floor panel below the first floor cross-member with a connection member interposed therebetween. Thus, the floor panel below the first floor cross-member is reinforced by the underfloor cross-member.

In addition, the underfloor cross-member is connected to the floor panel below the second floor cross-member. Thus, the floor panel below the second floor cross-member is reinforced by the underfloor cross-member.

Thus, the rigidity of the floor panel below the first floor cross-member is enhanced, and the rigidity of the floor panel below the second floor cross-member is enhanced. Accordingly, even if the floor cross-member and the underfloor cross-member partially have the fragile portion, a yield strength with respect to an impact load input laterally to the vehicle can be improved.

(37) In the vehicle body substructure according to any one of (4) and (29) to (36), the underfloor cross-member may have a recessed portion in which a downward recess is formed at the center in the vehicle width direction and may include a pipe accommodation portion which is attached to the recessed portion in a manner extending in the front-rear direction of a vehicle body and accommodates at least one of a piping and a hose.

In the vehicle body substructure according to (37) of the present invention, since the recessed portion is formed in the underfloor cross-member, the recessed portion can include the pipe accommodation portion. The pipe accommodation portion accommodates a piping, a hose, and the like.

In addition, since the recessed portion of the underfloor cross-member includes the pipe accommodation portion, the recessed portion is reinforced by the pipe accommodation portion. Thus, when a load is transmitted laterally to the underfloor cross-member of the vehicle, the pipe accommodation portion can withstand the transmitted load. Accordingly, the recessed portion can be prevented from being broken due to the transmitted load, and the underfloor cross-member can withstand the transmitted load.

Advantage of the Invention

According to the aspect of the present invention, the extending portion of the floor cross-member extends toward the upper portion of the side sill load transmitting member. In addition, the upper half portion of the underfloor load transmitting member faces the lower portion of the side sill load transmitting member. Moreover, the lower half portion of the underfloor load transmitting member is fixed to a part of the underfloor frame attached to the lower portion of the side sill.

Thus, an impact load input laterally to the vehicle can be transmitted via the transmission paths such as the first load path, the second load path, and the third load path. Accordingly, falling deformation of the side walls of the underfloor mounting component can be suppressed, and the underfloor mounting component can be protected from an impact load.

In addition, since an impact load input laterally to the vehicle is transmitted via the first to third load paths, there is no need to increase the heights of the side sills and provide the side sill load transmitting members inside the side sills. Accordingly, the side sills do not become a hindrance when an occupant boards and alights, so that boarding/alighting properties for an occupant can be ensured favorably.

In addition, the battery cross-member has the left and right side portion members and the central member having a substantially hat-shaped cross section. The upper surface of the central member is formed lower than the upper surfaces of the left and right side portion members. The recessed portion is constituted of the upper surface of the central member and the end portions of the left and right side portion members on the inner sides in the vehicle width direction. Therefore, the recessed portion can be used as an insertion groove for a distribution cable or the like, and a main portion of the battery cross-member can be constituted of a press-formed article or the like which can be manufactured at low cost.

In addition, each of the left and right side portion members of the battery cross-member is coupled to the floor cross-member thereabove and is coupled to the central member in the vicinity of a part below each of the coupling portions thereof. Therefore, while a structure in which the recessed portion allowing communication in the front-rear direction is provided substantially in a central region in the vehicle width direction is employed, a sufficient rigidity in the vehicle width direction can be ensured.

In addition, the forward protruding seat and the rearward protruding seat extend at the lower edge of the member main body portion of the battery cross-member, and the forward protruding seat and the rearward protruding seat are coupled to the bottom wall of the battery case. Therefore, when a load in the front-rear direction is input to the battery cross-member from the vehicle body-side cross-member through the fastening member, falling of the battery cross-member in the front-rear direction can be suppressed. Therefore, a support rigidity with respect to the vehicle body-side cross-member can be enhanced.

Moreover, the inclination portion is formed in the frame portion. Thus, a part of an impact load input laterally to the side sill of the vehicle can be transferred to the lower portion of the underfloor cross-member as a so-called offset load via the frame portion. In addition, the upper portion of the underfloor cross-member faces the side sill. Thus, a part of an impact load input laterally to the side sill of the vehicle can be transferred to the upper portion of the underfloor cross-member.

Accordingly, the underfloor mounting component can be protected from an impact load input laterally to the vehicle in a state where the lower surface of the battery pack is disposed below the side sills.

