Vehicle body

Abstract

A main body of a vehicle includes: a floor portion configured as a member molded by an extrusion process, a lower surface of the floor portion configured to cover an upper portion of a battery module to be accommodated in a lower battery case; and a pair of side members coupled to opposite side surfaces of the floor portion and extending in a longitudinal direction of the vehicle, each of the pair of side members including a first flange disposed at an inner surface of the side member facing the floor portion and extending in the longitudinal direction, the first flange is directly coupled to the lower surface of the floor portion by a first weld.

Description

Technical Field

[0001] The present invention relates to a vehicle body. Background Art

[0002] In electric vehicles, extending their driving range is an important development goal. As a solution for extending the driving range of electric vehicles, it includes increasing the battery capacity by increasing the number of battery cells and reducing the weight of each component of the electric vehicle, etc. However, increasing the battery capacity by increasing the number of battery cells necessarily involves an increase in the weight of the battery cells. Therefore, in this case, there are limitations in extending the driving range.

[0003] Many manufacturers are committed to such a solution, that is, by making the most effective use of the limited space of the vehicle to install the maximum number of battery cells, while reducing the weight of the battery system itself or reducing the weight of the vehicle.

[0004] Meanwhile, the battery of the electric vehicle is installed in the lower part of the vehicle body. Specifically, in the case where a plurality of battery modules are accommodated in a battery housing in a connected state, the battery is installed in the lower part of the vehicle body. In this regard, a technology is being developed to accommodate the battery modules in the lower battery housing and use the floor of the vehicle body as the upper battery housing while omitting the upper battery housing.

[0005] The above content disclosed in this section is only used to enhance the understanding of the general background of the present invention, and should not be regarded as an admission or an implication in any form that these contents form the known prior art. Summary of the Invention

[0006] The present invention relates to a vehicle body. The specific embodiment relates to a coupling structure between a side beam and a floor, and the floor constitutes a lower vehicle component in the vehicle body.

[0007] Therefore, in view of the problems in the art, embodiments of the present invention are proposed, and the embodiments of the present invention provide a vehicle body that includes a floor part (floorpart, bottom plate component) that can be used as an upper battery housing, a coupling structure between the floor part and the side beam, and a battery watertightness / airtightness maintaining structure, etc., for realizing the vehicle body.

[0008] According to an embodiment of the present invention, the above and other features can be achieved by providing a main body of such a vehicle, the main body of the vehicle including: a floor portion, a member configured to be formed by an extrusion process to constitute the floor of the vehicle, a lower surface of the floor portion being configured to cover an upper portion of a battery module accommodated in a lower battery case, thereby serving as an upper battery case; and side sills, coupled to opposite two side surfaces of the floor portion while extending in a longitudinal direction of the vehicle, the side sills including first flanges formed at inner surfaces of the side sills facing the floor portion and extending in the longitudinal direction, the first flanges being welded to the lower surface of the floor portion in a state of contacting the lower surface of the floor portion.

[0009] The lower surface of the floor portion and the first flange of the side sill can be joined to each other in a state of surface contact by friction stir spot welding (FSW) along the longitudinal direction of the first flange.

[0010] An area of contact with each other between the upper surface of the floor portion and the upper surface of the side sill can be welded by metal inert gas (MIG) welding.

[0011] A part of the upper surface of the side sill and a part of the upper surface of the floor portion can be connected to each other by a reinforcing member.

[0012] The reinforcing member can take the form of a member having a closed cross-section and extending at a predetermined length. A lower surface of the reinforcing member can be coupled to the upper surface of the side sill and the upper surface of the floor portion. One side surface of the reinforcing member can be in surface contact with the side sill to be supported by the side sill, thereby strengthening the hardness to resist side collisions.

[0013] When viewed in the height direction, the upper surface of the floor portion can be formed to be lower than the upper surface of the side sill. The lower surface of the reinforcing member can be in close contact with the upper surface of the side sill and the upper surface of the floor portion arranged at different heights through a stepped portion.

[0014] The floor portion can be extruded and formed in the width direction of the vehicle. Downwardly extending barrier walls can be respectively formed at a front end and a rear end of the floor portion to be integrally formed with the floor portion. The downwardly extending barrier walls cover side surfaces of outermost battery modules among a plurality of battery modules.

[0015] An extension protruding in a downward direction of the vehicle can be formed in an area corresponding to an edge of the floor portion at the lower surface of the floor portion, such that the first flange and the lower surface of the floor portion adjacent to the first flange are flush with each other.

[0016] The thickness of the extension can be equal to the thickness of the first flange of the side sill.

[0017] The welded portion between the first flange of the side beam and the lower surface of the floor portion may start from the extension portion of the floor portion.

[0018] The rear end of the floor portion may have a trapezoidal shape. A joint (seam) may be welded to the rear end of the floor portion at the edge of the floor portion. A second flange may be formed at the inner surface of the joint facing the floor portion. The second flange may be welded to the lower surface of the floor portion in a state of contacting the lower surface of the floor portion.

[0019] Extension portions protruding in the downward direction of the vehicle may be respectively formed in regions corresponding to the edges of the floor portion at the lower surface of the floor portion. The lower surface of one extension portion formed at the front end of the floor portion may be flush with the lower surface of the floor portion of the side beam. The lower surface of the other extension portion formed at the rear end of the floor portion may be flush with the lower surface of the second flange of the joint.

[0020] The thickness of the second flange, the thickness of the extension portion formed at the rear end edge of the floor portion, and the thickness of the first flange of the side beam may be equal.

[0021] The welded portion between the first flange of the side beam and the lower surface of the floor portion may start from the extension portion at the front end of the floor portion and may end at the extension portion at the rear end of the floor portion.

[0022] The regions in contact with each other between the joint and the side beam and the regions between the joint and the barrier wall of the floor portion may be welded by metal inert gas (MIG) welding. The lower surface of the floor portion and the second flange may be welded to each other by friction stir spot welding.

[0023] The floor portion may include a plurality of extruded members extruded in the width direction of the vehicle.

[0024] The plurality of extruded members may be aligned with each other in the longitudinal direction of the vehicle. Adjacent extruded members among the plurality of extruded members may be welded to each other by friction stir spot welding in a state of surface contact with each other, thereby forming the floor portion.

[0025] The plurality of extruded members may include a first extruded member, a second extruded member, and a third extruded member having different heights respectively. A seat mounting member for mounting a seat may be formed at the first extruded member, and the first extruded member extends upward to a level higher than the levels of the second extruded member and the third extruded member. The third extruded member extending downward to a level lower than the levels of the first extruded member and the second extruded member may be disposed at the front end and the rear end of the floor portion, thereby forming a space at the lower surface of the floor portion. Description of the Drawings

[0026] The above and other objects, features, and other advantages of the embodiments of the present invention will be more clearly understood from the following detailed description in conjunction with the accompanying drawings, in which:

[0027] Figure 1 The installation of the battery on the lower side is shown;

[0028] Figure 2 and Figure 3 is a view showing a cross-section of the main body of a vehicle according to an embodiment of the present invention;

[0029] Figure 4 The lower surface of the main body of a vehicle according to an embodiment of the present invention is shown;

[0030] Figure 5 An enlarged view of the rear end of the floor portion is shown; and

[0031] Figure 6 A cross-section taken along the longitudinal direction of the vehicle is shown. Detailed Embodiments

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Throughout the drawings, the same reference numerals are used to denote the same or similar elements, and redundant descriptions thereof will be omitted.

[0033] In the following description of the embodiments of the present invention, when the known functions and configurations incorporated herein may obscure the subject matter of the embodiments of the present invention, detailed descriptions thereof will be omitted. In addition, the embodiments of the present invention will be more clearly understood from the drawings, and the embodiments of the present invention should not be limited by the drawings, and it should be understood that all changes, equivalents, and substitutions that do not depart from the spirit and technical scope of the present invention are included in the present invention.

[0034] It should be understood that although the terms "first", "second", etc. may be used herein to describe multiple elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0035] Unless clearly used otherwise, singular expressions include plural meanings.

[0036] In this specification, the terms "comprising", "including", etc. are intended to express the presence of features, numbers, steps, operations, elements, parts, or combinations thereof, and do not exclude the presence of another feature, number, step, operation, element, part, or any combination or any addition thereof.

[0037] In the case where one component is "connected" or "linked" to another component, it should be understood that the component can be directly connected or linked to other components, or there may be another component between them. Conversely, in the case where one component is "directly connected" or "directly linked" to another component, it should be understood that there is no other component between them.

[0038] Figure 1 The installation of the battery on the lower side is shown. Refer to Figure 1 , the battery is installed in the lower part of the floor portion 130 constituting the floor 100 of the vehicle. Specifically, a receiving space for accommodating a plurality of battery modules 200 may be provided at the lower battery housing 300, and the lower battery housing 300 may be coupled to the vehicle body below the floor portion 130 of the vehicle.

[0039] That is, in a conventional battery, its battery modules are installed in a lower battery housing, an upper battery housing is coupled to the lower battery housing, and the final structure is coupled to the vehicle body. In contrast, in an embodiment of the present invention, the lower battery housing 300 accommodating the battery modules 200 may be coupled to the vehicle body, omitting the upper battery housing.

[0040] Since the battery is an electronic device, the battery should be isolated from the external environment as much as possible. For this reason, usually, a sealant is coated on the battery to prevent water or foreign matter from being introduced from the outside of the vehicle body. However, the sealant is not sufficient to ensure a perfect level of airtightness and watertightness. Specifically, it may be difficult for the sealant to ensure high-pressure watertight performance.

[0041] In all electric vehicles, a perfect level of airtightness and watertightness needs to be ensured. Specifically, in the embodiment of the present invention where the upper battery housing is omitted, this requirement is very high.

[0042] To ensure a perfect level of airtightness and watertightness, an embodiment of the present invention proposes to join the respective components by welding to ensure airtightness and watertightness while minimizing the use of sealant.

[0043] Hereinafter, the joining structure between the floor portion 130 and the side beam 150 for ensuring airtightness and watertightness will be described.

[0044] Figure 2 and Figure 3 are views showing a cross-section of a vehicle body according to an embodiment of the present invention. Refer to Figure 2 and Figure 3 , the side beam 150 and the floor portion 130 are joined to each other to constitute the floor 100 of the vehicle.

[0045] Specifically, the floor portion 130 is made of an aluminum material and formed by an extrusion process to adopt the form of a member. The floor portion 130 in the form of a member has an upper surface and a lower surface. A seat mounting member (to which a seat will be coupled) may be formed at the upper surface of the floor portion 130. The lower surface of the floor portion 130 covers the upper portion of the battery module 200 accommodated in the lower battery case 300, and thus, the floor portion 130 may serve as an upper battery case.

[0046] In addition, since the floor portion 130 is in the form of a member, the floor portion 130 may have the effect of a multi-channel structure capable of distributing loads during a side collision of the vehicle.

[0047] The side beams 150 extend in the longitudinal direction of the vehicle and are coupled to opposite two side surfaces of the floor portion 130. To protect the battery during a side collision of the vehicle, the side beams 150 may have a plurality of closed cross-sections.

[0048] Meanwhile, to couple the side beams 150 to the floor portion 130, a first flange 155 extending in the longitudinal direction is formed at the inner surface of the side beam 150 facing the floor portion 130. When the side beam 150 is disposed at the floor portion 130 to couple the side beam 150 to the floor portion 130, the first flange 155 of the side beam 150 is disposed at the lower surface of the floor portion 130.

[0049] In a state where the lower surface of the floor portion 130 and the first flange 155 of the side beam 150 are in surface contact with each other, a welding machine 900 welds the first flange 155 and the lower surface of the floor portion 130 to each other below the floor portion 130. The welding machine 900 welds the side beam 150 and the floor portion 130 along the longitudinal direction of the first flange 155. The welding method in this case is preferably friction stir spot welding (FSW).

[0050] To use the floor portion 130 as an upper battery case, a structure capable of ensuring watertightness and airtightness when the side beam 150 and the floor portion 130 are coupled to each other is required. In this regard, the first flange 155 is formed at the side beam 150, and the lower surface of the floor portion 130 and the first flange 155 are welded to each other, and thus, watertightness and airtightness can be ensured.

[0051] The first flange 155 and the lower surface of the floor portion 130 in surface contact with each other are welded to each other by friction stir spot welding, while the contact area between the upper surface of the floor portion 130 and the upper surface of the side beam 150 is welded to each other by metal inert gas (MIG) welding. Therefore, the connection between the floor portion 130 and the side beam 150 can be further strengthened.

[0052] That is, the seat mounting member is formed at the upper surface of the floor portion 130. Since each component other than the side beam 150 can be coupled to the seat mounting member, unlike the lower surface of the floor portion 130, the upper surface of the floor portion 130 can be formed to be curved. For this reason, the upper surface of the floor portion 130 is preferably welded by MIG welding.

[0053] Since the floor portion 130 and the side beam 150 are welded to each other as described above, foreign substances can be prevented from being introduced into the interior of the battery from the outside.

[0054] Meanwhile, the side beam 150 is welded to the floor portion 130 in the longitudinal direction of the vehicle, and thus, airtightness and watertightness at the side portion of the vehicle are ensured.

[0055] Barrier walls 131 extending downward are respectively formed at the front end and the rear end of the floor portion 130 ( Figure 4 ), and these barrier walls are extruded together with the floor portion 130 when the floor portion 130 is extruded. By the barrier walls 131 formed at the front end and the rear end of the floor portion 130, airtightness and watertightness at the front side and the rear side of the vehicle can also be ensured.

[0056] Figure 4 The lower surface of the main body of the vehicle according to an embodiment of the present invention is shown. Referring to Figure 4 , barrier walls 131 extending downward are respectively formed at the front end and the rear end of the floor portion 130.

[0057] The barrier wall 131 can cover the side surface of the battery module 200, and the lower surface of the floor portion 130 can cover the upper portion of the battery module 200. Therefore, the floor portion 130 can function as an upper battery case.

[0058] Specifically, since the barrier wall 131 is integrally formed at the floor portion 130 to ensure airtightness and watertightness at the front end and the rear end of the floor portion 130, the airtightness and watertightness of the battery can be maintained only by welding the side beam 150 to the floor portion 130.

[0059] That is, if separate components for maintaining airtightness and watertightness are introduced at the front end and the rear end of the floor portion 130 and the barrier wall 131 is not formed at the floor portion 130, welding needs to be performed along the entire periphery of the floor portion 130, and thus, time and cost are increased. However, in the case where the barrier wall 131 is integrally formed at the floor portion 130, only the side beam 150 needs to be welded.

[0060] Meanwhile, since the first flange 155 of the side beam 150 and the lower surface of the floor portion 130 are welded to each other, the connection between the side beam 150 and the floor portion 130 is achieved. Although welding from the front end to the rear end of the first flange 155 is sufficient to achieve the connection between the side beam 150 and the floor portion 130, in order to achieve perfect airtightness and watertightness, it is preferable that the welding starts from the side portion of the first flange 155.

[0061] That is, referring to Figure 4 the welding position A between the first flange 155 and the lower surface of the floor portion 130 shown in, the welding can start from the side portion of the first flange 155 to achieve airtightness and watertightness.

[0062] For friction stir spot welding, the first flange 155 and the side portion of the first flange 155 (i.e., the lower surface of the floor portion 130 adjacent to the first flange 155) should be flush with each other. In order to make the first flange 155 and the lower surface of the floor portion 130 adjacent to the first flange 155 flush with each other, an extension portion 133 protruding in the downward direction of the vehicle can be formed at the lower surface of the floor portion 130 in a region corresponding to the edge of the floor portion 130.

[0063] As Figure 4 shown, the extension portion 133 is formed adjacent to each barrier wall 131 and protrudes downward, different from the lower surface of the floor portion 130 adjacent to the extension portion 133. That is, since the first flange 155 is provided at the side beam 150, in order to perform friction stir spot welding between the side beam 150 and the floor portion 130, the first flange 155 is arranged lower than the lower surface of the floor portion 130.

[0064] For this reason, the downward protruding extension portion 133 is formed at a predetermined portion of the lower surface of the floor portion 130 so that the first flange 155 and the lower surface of the floor portion 130 can be flush with each other. Therefore, it is preferable to extrude the floor portion 130 in consideration of this situation.

[0065] The thickness of the extension portion 133 is preferably equal to the thickness of the first flange 155 of the side beam 150. Therefore, the extension portion 133 and the first flange 155 of the side beam 150 are arranged in the same plane.

[0066] Therefore, as Figure 4 shown, the welding between the first flange 155 of the side beam 150 and the floor portion 130 can start from the extension portion 133 of the floor portion 130. Therefore, airtightness and watertightness of the battery can be ensured at all side portions of the floor portion 130.

[0067] Meanwhile, although the overall shape of the floor portion 130 may be rectangular, it is preferable that the shape of the front end of the floor portion 130 is quadrilateral and the shape of the rear end of the floor portion 130 is trapezoidal in order to maximize the use of limited space and thus ensure the desired battery capacity.

[0068] That is, the rear side member is coupled to the rear end of the floor 100 of the vehicle body, and thus, even in the case of using the coupling portion of the rear side member, the rear end of the floor portion 130 protrudes in a trapezoidal shape in order to mount the battery module 200.

[0069] Of course, when the rear end of the floor portion 130 protrudes, an empty space may be formed between the side beam 150 and the barrier wall 131 formed at the rear end of the floor portion 130 (specifically, at the rear edge of the floor portion 130). In order to fill this empty space, the joint portion 500 may be welded at the rear edge of the floor portion 130.

[0070] The joint portion 500 should also be welded to the lower surface of the floor portion 130 in order to ensure the airtightness and watertightness of the battery. To this end, the joint portion 500 further includes a second flange 505 formed on the inner surface of the joint portion 500 facing the floor portion 130. The second flange 550 has the same function as the first flange 155 of the side beam 150.

[0071] Therefore, the second flange 505 makes surface contact with the lower surface of the floor portion 130, and thus, it can be welded by friction stir spot welding.

[0072] Meanwhile, similar to the extension portion 133 formed on the lower surface of the floor portion 130 adjacent to the barrier wall 131 at the front end of the floor portion 130, it is preferable that another extension portion 133 is formed on the lower surface of the floor portion 130 and adjacent to the barrier wall 131 at the rear end of the floor portion 130 in order to ensure the airtightness and watertightness of the battery.

[0073] Specifically, welding should be performed between the side beam 150 and the joint portion 500 and between the joint portion 500 and the barrier wall 131 at the rear end of the floor portion 130 in order to ensure the airtightness and watertightness between the side beam 150 and the joint portion 500 and the airtightness and watertightness between the barrier wall 131 at the rear end and the joint portion 500.

[0074] In order to apply friction stir spot welding as the welding method, the extension portion 133 is formed on the lower surface of the floor portion 130 and adjacent to the barrier wall 131 at the rear end of the floor portion 130. In the case of performing friction stir spot welding on the extension portion 133 adjacent to the barrier wall 131 at the rear end, the airtightness and watertightness of the battery can be ensured.

[0075] Similar to the extension portion 133 formed at the front end of the floor portion 130, the extension portion 133 formed at the rear end of the floor portion 130 has the same thickness as the second flange 505 and the same thickness as the first flange 155.

[0076] Therefore, the extension portion 133 formed at the rear end of the floor portion 130, the second flange 505 of the joint portion 500, and the first flange 155 are arranged in the same plane, and thus, friction stir spot welding can be performed along the same plane as described above.

[0077] The welding direction is determined such that the welding starts from the extension portion 133 at the front end of the floor portion 130 and ends at the extension portion 133 at the rear end of the floor portion 130. However, the welding direction can be determined such that the welding starts from the extension portion 133 at the rear end of the floor portion 130 and ends at the extension portion 133 at the front end of the floor portion 130.

[0078] That is, friction stir spot welding can be performed twice on the left and right sides of the floor portion 130, and thus, perfect battery airtightness and watertightness can be ensured.

[0079] In addition, referring to Figure 5 , the area where the joint portion 500 and the side beam 150 are in contact with each other can be welded by MIG welding, and the area between the joint portion 500 and the floor portion 130 can also be welded by MIG welding. In this case, the airtightness and watertightness of the battery can be further enhanced.

[0080] Meanwhile, a part of the upper surface of the side beam 150 and a part of the upper surface of the floor portion 130 can be connected to each other by the reinforcing member 700. Referring to Figure 2 and Figure 3 , it can be seen that the reinforcing member 700 is provided to extend on both the upper surface of the side beam 150 and the upper surface of the floor portion 130.

[0081] The reinforcing member 700 is a member configured to strengthen the hardness to resist the load applied from the side surface of the vehicle, and is in the form of a member having a closed cross-section and extending for a predetermined length. The lower surface of the reinforcing member 700 is joined to the upper surface of the side beam 150 and the upper surface of the floor portion 130. In this case, one side surface of the reinforcing member 700 is in contact with the side beam 150 surface and is thus supported by the side beam 150, thereby strengthening the hardness to resist side collisions.

[0082] Specifically, when viewed in the height direction, the upper surface of the floor portion 130 is formed to be lower than the upper surface of the side sill 150. Due to this structure, a stepped portion 153 that is exposed to the floor portion 130 is formed at the upper surface of the side sill 150. Accordingly, the lower surface of the reinforcing member 700 can be in close contact with the upper surfaces of the side sill 150 and the floor portion 130 that are disposed at different height levels.

[0083] Meanwhile, the lower battery case 300 in which the battery module 200 is installed is coupled to the vehicle body having the above configuration at the lower side. Refer to Figure 2 , an installation portion for installing the lower battery case 300 is formed at the side sill 150, and the lower battery case 300 is fastened to the installation portion of the side sill 150 by bolts or the like, and thus can be fixed to the vehicle body.

[0084] Meanwhile, the floor portion itself can be formed by coupling a plurality of extruded members.

[0085] Figure 6 is a view showing a cross-section taken along the longitudinal direction of the vehicle. Refer to Figure 6 , it can be seen that the floor portion is formed by coupling a plurality of extruded members to each other.

[0086] Specifically, to form the floor portion, a plurality of extruded members that are extrusion-molded along the width direction of the vehicle are prepared, and the prepared extruded members are aligned with each other along the longitudinal direction of the vehicle. Adjacent extruded members among the plurality of extruded members are in a state of being in surface contact with each other along the width direction of the vehicle. The floor portion can be formed by welding adjacent extruded members.

[0087] In this case, friction stir spot welding is performed to ensure the airtightness and watertightness of the floor portion.

[0088] Meanwhile, the plurality of extruded members forming the floor portion may include a first extruded member 135, a second extruded member 137, and a third extruded member 139 that respectively have different heights.

[0089] The first extruded member 135 may extend upward to a height level higher than the other extruded members. In this case, a seat mounting member for mounting a seat may be formed at the first extruded member 135.

[0090] The third extruded member 139 may extend downward to a height level lower than the other extruded members. In this case, the third extruded member 139 may be disposed at the front end and the rear end of the floor portion, thereby forming a space at the lower surface of the floor portion.

[0091] That is to say, when the first extrusion member 135, the second extrusion member 137, and the third extrusion member 139 are coupled to each other, a space for accommodating a battery module or the like is formed at the lower surface of the plurality of extrusion members, and the third extrusion member 139 functions as a barrier wall.

[0092] According to the vehicle body having the above configuration, the upper battery case can be omitted, and thus, the weight of the vehicle can be reduced. Although the upper battery case is omitted, the airtightness and watertightness of the battery can be ensured by welding.

[0093] It is obvious from the above description that the advantage of the vehicle body according to the embodiment of the present invention is that the floor portion can function as the upper battery case, and thus, the weight can be reduced by omitting the upper battery case to achieve weight reduction. In addition, there is also an advantage that the floor portion can be welded by friction stir spot welding to maintain the watertightness / airtightness of the battery while functioning as the upper battery case.

[0094] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art should understand that various modifications, additions, and substitutions can be made without departing from the scope and spirit of the present invention disclosed in the appended claims.

Claims

1. A vehicle body, comprising: a floor portion configured as a member formed by an extrusion process, a lower surface of the floor portion configured to cover upper portions of a plurality of battery modules to be accommodated in a lower battery housing; as well as A pair of side beams are coupled to two opposite side surfaces of the floor portion and extend in the longitudinal direction of the vehicle, each of the side beams comprising a first flange that is arranged at an inner surface of the side beam facing the floor portion and extends in the longitudinal direction, wherein the first flange is directly coupled to a lower surface of the floor portion through a first welding portion.

2. The vehicle body according to claim 1, wherein: The lower surface of the floor portion and the first flange of the side member are coupled to each other in the longitudinal direction of the vehicle by friction stir spot welding in a state of surface contact.

3. The vehicle body according to claim 1, wherein: An area where an upper surface of the floor portion and an upper surface of the side member contact each other includes a second welded portion formed by metal inert gas welding.

4. The vehicle body according to claim 1, wherein: A portion of the upper surface of the pair of side members and a portion of the upper surface of the floor portion are connected to each other through a reinforcement member.

5. The vehicle body according to claim 4, wherein: The reinforcement member includes a second member having a closed cross-section and extending at a predetermined length; A lower surface of the reinforcement is coupled to the upper surfaces of a pair of the side members and the upper surface of the floor portion; and The first side surface of the reinforcement member is in surface contact with one of the pair of side members to be supported by the side member.

6. The vehicle body according to claim 5, wherein: When viewed in a height direction, the upper surface of the floor portion is arranged lower than the upper surface of the side member; and The lower surface of the reinforcement is in close contact with the upper surfaces of the pair of side members arranged at different heights through a step portion and the upper surface of the floor portion.

7. The vehicle body according to claim 1, wherein: The floor portion is extruded along the width direction of the vehicle; A downwardly extending barrier wall is disposed at both the front and rear ends of the floor portion, wherein the barrier wall is integrally formed with the floor portion; and The barrier wall is configured to cover a side surface of an outermost battery module among the plurality of battery modules.

8. The body of the vehicle according to claim 1 further includes an extension portion protruding in a downward direction of the vehicle, wherein the extension portion is arranged in an area corresponding to an edge of the floor portion at the lower surface of the floor portion so that the first flange and the lower surface of the floor portion adjacent to the first flange are flush with each other.

9. The vehicle body according to claim 8, wherein: The thickness of the extension portion is equal to the thickness of the first flange of the side member.

10. The vehicle body according to claim 8, wherein: The first weld between the first flange of the side member and the lower surface of the floor portion starts from the extended portion of the floor portion.

11. The vehicle body according to claim 1, wherein: The rear end of the floor portion has a trapezoidal shape; The rear end of the floor portion is coupled with a joint portion at an edge of the floor portion by a second welding portion; A second flange is arranged at an inner surface of the joint portion facing the floor portion; and The second flange is coupled to the lower surface of the floor portion by a third welding portion in a state of contacting the lower surface of the floor portion.

12. The vehicle body according to claim 11, further comprising: a first extension portion protruding in a downward direction of the vehicle and arranged at the lower surface of the floor portion at a front end of the floor portion, the lower surface of the first extension portion being flush with lower surfaces of the pair of side members; as well as A second extension portion protrudes in the downward direction of the vehicle and is arranged at the lower surface of the floor portion at the rear end of the floor portion, a lower surface of the second extension portion being flush with a lower surface of the second flange of the engaging portion.

13. The vehicle body according to claim 12, wherein: The thickness of the second flange, the thickness of the second extension portion at the rear end of the floor portion, and the thickness of the first flanges of the pair of side members are equal.

14. The vehicle body according to claim 12, wherein: The first weld between the first flange of the side member and the lower surface of the floor portion starts from the first extension of the floor portion and ends at the second extension of the floor portion.

15. The vehicle body according to claim 11, wherein: The area between the joint portion and the side member in contact with each other and the area between the joint portion and the barrier wall of the floor portion are coupled by metal inert gas welding; and The lower surface of the floor portion and the second flange are coupled to each other by friction stir spot welding.

16. A vehicle body, comprising: a floor portion including a plurality of extrusion members extruded in a width direction of the vehicle and aligned with each other in a longitudinal direction of the vehicle, a lower surface of the floor portion being configured to cover upper portions of a plurality of battery modules to be accommodated in a lower battery housing; as well as A pair of side beams are coupled to opposite side surfaces of the floor portion and extend in the longitudinal direction of the vehicle, each of the side beams comprising a first flange that is arranged at an inner surface of the side beam facing the floor portion and extends in the longitudinal direction, wherein the first flange is directly coupled to the lower surface of the floor portion through a first welding portion.

17. The vehicle body according to claim 16, wherein: Adjacent extrusion members among the plurality of extrusion members are coupled to each other by friction stir spot welding in a state of surface contact with each other to define the floor portion.

18. The vehicle body according to claim 16, wherein: The plurality of extrusion members include a first extrusion member, a second extrusion member and a third extrusion member having different heights respectively; A seat mount is disposed at the first extruded member, the first extruded member extending upward to a height greater than the heights of the second extruded member and the third extruded member; and The third extruded member extends downward to a height lower than those of the first and second extruded members and is arranged at the front and rear ends of the floor portion to define a space at the lower surface of the floor portion.

19. The vehicle body of claim 16, wherein: The rear end of the floor portion has a trapezoidal shape; The rear end of the floor portion is coupled with a joint portion at an edge of the floor portion by a second welding portion; A second flange is arranged at an inner surface of the joint portion facing the floor portion; and The second flange is coupled to the lower surface of the floor portion by a third welding portion in a state of contacting the lower surface of the floor portion.

20. The vehicle body of claim 19, wherein: The area between the joint portion and the side member in contact with each other and the area between the joint portion and the barrier wall of the floor portion are coupled by metal inert gas welding; and The lower surface of the floor portion and the second flange are coupled to each other by friction stir spot welding.

Images