Body side structure

Abstract

The vehicle body side structure (1) related to the present invention comprises a side sill (3) formed by joining a side sill inner (3a) and a side sill outer (3b), a battery pack (5) formed positioned on the vehicle side in the vehicle width direction relative to the side sill (3), and a floor cross member (7) extended in the vehicle width direction. The floor cross member (7) is made of a metal plate having a tensile strength of 1180 MPa or higher, and its end (7a) is formed to be positioned so as not to come into contact with the side (3a1) of the side sill inner (3a) but to cover the upper surface (3a2), and extends to come into contact with the joining surface (3d) at the upper part (3c) of the side sill inner (3a) and the side sill outer (3b). In the event of a side collision, after the side sill outer (3b) is deformed and crushed, the load input to the side sill (3) is transferred to the floor cross member (7) reduces the load transmitted to the battery pack (5) by transmitting it to (7).

Description

Technology Field

[0001] The present invention relates to an automotive body side structure, such as that of a battery electric vehicle, in which a battery pack is disposed and formed on the inner side of the vehicle width direction relative to the side sill. Background Technology

[0002] Recently, particularly in the automotive industry, there has been a shift from gasoline engine cars to electric vehicles due to environmental concerns. Electric vehicles and similar vehicles have battery packs containing large batteries placed in the floor area of ​​the vehicle body. Furthermore, since these batteries often use lithium-based materials, there is a risk of fire if the battery pack is damaged and liquid leaks from the battery during a collision; therefore, a structure to protect the battery pack is required. To protect this battery pack, there is a floor cross member extending in the width direction and side sills extending in the length direction from both outer sides in the width direction. The floor cross member is positioned between the two side sills, and the battery pack is positioned underneath it.

[0003] As a technology for protecting a battery pack during a side impact collision of an electric vehicle, for example, Patent Document 1 discloses a structure in which a battery pack, a side sill formed extending in the front-rear direction of the vehicle body on the outer side in the width direction, and a floor cross member installed between the left and right side sills are connected from the side portion on the inner side of the side sill inner in the side sill to the joint portion between the side sill inner and the side sill outer. Prior art literature

[0004] Japanese Patent Publication No. 6734709 The problem to be solved

[0005] In the technology disclosed in Patent Document 1, during a side collision in which a load is input by a pole or the like colliding with the side sill on the side of a vehicle, the collision load is transmitted from the side sill to the floor cross member through the connection portion between the side sill and the floor cross member extending from the side portion on the interior side of the side sill inner to the joint portion between the side sill outer and the side sill inner. Then, as the reaction force is amplified by the floor cross member, the side sill outer and side sill inner are crushed, and The side sill outer and side sill inner efficiently absorb crush energy by being compressed. However, if the side sill is compressed, the load transmitted to the battery pack cannot be sufficiently reduced, and thus the battery pack cannot be sufficiently protected.

[0006] The present invention is made to solve the above problem, and its purpose is to provide a vehicle body side structure capable of protecting a battery pack by reducing the load transmitted to the battery pack during a side collision of a vehicle body equipped with a side sill, a battery pack formed on the interior side of the vehicle width direction of the side sill, and a floor cross member. means of solving the problem

[0007] The vehicle body side structure related to the present invention comprises a side sill formed by joining a side sill inner and a side sill outer, which are extended in the front-rear direction of the vehicle body on the outer side of the vehicle body in the width direction, at the upper and lower portions in the height direction; a battery pack disposed and formed at the lower part of the vehicle body on the inner side of the vehicle body in the width direction relative to the side sill; and a floor cross member, which is extended in the width direction relative to the upper side of the inner side of the vehicle body in the width direction relative to the side sill. The floor cross member is made of a metal sheet having a tensile strength of 1180 MPa class or higher, and the end on the outer side of the vehicle body in the width direction does not come into contact with the inner side of the side sill in the width direction, and is disposed and formed to cover the upper surface of the side sill inner in the height direction, and extends to and comes into contact with the joining surface portion at the upper portion of the side sill inner and the side sill outer, and extends from the outer side of the vehicle body in the width direction to the side sill In the event of a side collision in which a crushing load is applied, after the side sill outer is deformed and crushed, the load applied to the side sill is transferred to the floor cross member to reduce the load transferred to the battery pack.

[0008] The floor cross member has a groove shape extending in the vehicle width direction, and a wall portion is formed at its leading end that abuts the joint surface portion, and the groove shape at the end of the floor cross member is closed by the wall portion.

[0009] The above end of the floor cross member may be connected to the joint surface of the side sill inner and the side sill outer. Effects of the invention

[0010] In the present invention, a load transfer path for a load applied to the vehicle body during a side collision is formed in the floor cross member, and the reaction force from the floor cross member toward the vehicle's width direction is mainly applied to the joining surface where the side sill inner and side sill outer are joined. Accordingly, the side sill outer absorbs collision energy by being compressed and deformed, while the side sill inner maintains its shape without being compressed. In addition, since the floor cross member is made of a metal plate with a tensile strength of 1180 MPa or more, the floor cross member can continue to receive the load applied to the side sill without deformation even after the side sill outer is compressed and deformed. Accordingly, the side sill inner becomes less likely to be deformed and deformed, and can maintain its impact energy absorption capacity, thereby reducing the load transfer to the battery pack (5). As a result, it is possible to suppress deformation of the battery pack (5) during a side collision and protect the battery pack from damage, making it possible to create a safe vehicle. Brief explanation of the drawing

[0011] FIG. 1 is a drawing illustrating a vehicle body side structure related to an embodiment of the present invention. FIG. 2 is a diagram illustrating the transfer of load during a side collision in a vehicle body side structure related to an embodiment of the present invention ((a) a conventional vehicle body side structure, (b) a vehicle body side structure related to the present embodiment, (c) a load transfer path during a side collision). FIG. 3 is a drawing showing a specific example in which the end of a floor cross member has a closed shape in a side structure of a vehicle body related to an embodiment of the present invention. FIG. 4 is a diagram illustrating a side collision of a vehicle body that is the subject of analysis in an embodiment. FIG. 5 is a diagram illustrating a method for evaluating the amount of deformation of a battery pack and the input load on the battery pack in an embodiment ((a) evaluation location of the amount of deformation of the battery pack, (b) input load on the battery pack). FIG. 6 is a cross-sectional view of a vehicle body side structure related to the inventive example and comparative examples 1 and 2 in the embodiment at (i) a longitudinal position TL = 1568 mm and (ii) a longitudinal position TL = 1916 mm ((a) inventive example, (b) comparative example 1, (c) comparative example 2). FIG. 7 is a graph showing the result of the amount of deformation of the battery pack when a pole collides at the longitudinal position TL = 1916 mm in the embodiment. FIG. 8 is a graph showing the result of the contact reaction force obtained as the input load for the battery pack when the pole collides at the longitudinal position TL = 1916 mm in the embodiment. Specific details for implementing the invention

[0012] The vehicle body side structure (1) related to an embodiment of the present invention comprises a side sill (3), a battery pack (5), a floor cross member (7), and a floor panel (9), as shown as an example in FIG. 1.

[0013] Hereinafter, with reference to FIG. 1, a side body structure (1) related to the present embodiment will be described. FIG. 1 shows other body parts such as a floor panel (9) formed above the battery pack (5), but in the following description, since these other body parts are not the main parts of the present invention, their description will be omitted. Also, in this specification and drawings, elements having the same functional configuration are given the same reference numeral to omit redundant descriptions.

[0014] As shown in FIG. 1, the side sill (3) is provided with a side sill inner (3a) and a side sill outer (3b) that are extended in the front-rear direction of the vehicle body on the outer side of the vehicle body in the width direction. The side sill inner (3a) has a groove shape that opens toward the outer side of the vehicle in the width direction by means of a ceiling plate (3a1) and a pair of vertical walls (3a2), and the side sill outer (3b) has a groove shape that opens toward the inner side of the vehicle in the width direction. Then, the side sill inner (3a) and the side sill outer (3b) are joined at the upper part (3c) and lower part (not shown) in the height direction of the vehicle so that their opening sides face each other, thereby forming a closed cross-section structure.

[0015] In the vehicle body side structure (1) shown in FIG. 1, the upper portion of the side sill (3) in the vehicle height direction is shown as being approximately 1 / 3 or more of the area. The side sill inner (3a) and the side sill outer (3b) are, for example, of a hat-shaped cross section having a top portion, a pair of vertical walls, and a flange portion, and the upper and lower flanges of the side sill inner (3a) and the side sill outer (3b) are joined together to form a side sill (3) with a closed cross section structure. However, in the present invention, the side sill inner and the side sill outer are not limited to having a hat-shaped cross section, and it is sufficient if their respective upper and lower portions are joined together to form a side sill with a closed cross section structure.

[0016] As shown in FIG. 1, the battery pack (5) is formed by being positioned on the lower part of the vehicle body in the vehicle width direction from the side sill (3), and has a battery cell (not shown) mounted inside.

[0017] The floor cross member (7) has a hat-shaped cross section having a bottom portion, a pair of vertical walls, and a flange, and has a groove shape that extends in the vehicle width direction by the bottom portion and the pair of vertical walls. As shown in FIG. 1, the floor cross member (7) is formed to extend in the vehicle width direction above the side sill (3) in the vehicle width direction. In the cross-sectional view of the vehicle body side structure of FIG. 1, the cross section of the bottom portion is shown. The floor cross member (7) is made of a metal plate with a tensile strength of 1180 MPa or higher. The end portion (7a) on the vehicle width direction outside the vehicle does not come into contact with the vehicle width direction inner surface of the side sill inner (3a), and is formed to cover the upper surface in the vehicle height direction of the side sill inner (3a). Additionally, the side sill inner (3a) and the side sill outer (3b) are joined to a joint surface (3d) and are in contact with each other. The upper surface of the side sill inner (3a) in the vehicle height direction refers to the vertical wall (3a2) in the case where the side sill inner (3a) has a hat cross-sectional shape having a ceiling plate (3a1), a vertical wall (3a2), and a flange (3a3) as shown in FIG. 1. Also, the inner surface of the side sill inner (3a) in the vehicle width direction refers to the ceiling plate (3a1).

[0018] And, in the case of a side collision in which a collision load is input to the side sill (3) from the outer side of the vehicle in the width direction, the side sill outer (3b) is compressed and deformed by the collision load input to the side sill (3). In addition, after the side sill outer (3b) is deformed, the floor cross member (7) continues to receive the load input to the side sill (3) without deforming, thereby reducing the load transmitted to the battery pack (5).

[0019] The effects of the vehicle body side structure (1) related to the present embodiment are as follows. In a conventional vehicle body side structure (21) equipped with a side sill (3), a battery pack (5), and a floor cross member (23), as shown as an example in FIG. 2(a), the end (23a) in the width direction of the floor cross member (23) extends upward from the side sill inner (3a), but it does not come into contact with the joint surface (3d) at the upper part (3c) of the side sill (3). Therefore, when a load is applied to the side sill (3) during a side collision, the side sill outer (3b) is first deformed and crushed, and then the load is not sufficiently transferred to the floor cross member (23), so the load transfer to the battery pack (5) cannot be sufficiently reduced.

[0020] In contrast, according to the vehicle body side structure (1) related to the present embodiment, as shown in FIG. 1 and FIG. 2(b), the end (7a) of the floor cross member (7) is in contact with the joint surface (3d) at the upper part (3c) of the side sill (3), so that, as shown in FIG. 2(c), a load transfer path of the load input to the vehicle body during a side collision is formed in the floor cross member (7). And, the reaction force to the outside of the vehicle in the width direction by the floor cross member (7) is mainly applied to the joint surface (3d) where the side sill inner (3a) and the side sill outer (3b) are joined. Accordingly, the side sill outer (3b) absorbs collision energy by being compressed and deformed, but the side sill inner (3a) can maintain its shape without being compressed. In addition, since the floor cross member (7) is made of a metal plate with a tensile strength of 1180 MPa or more, even after the side sill outer (3b) is compressed and crushed, the floor cross member (7) can continue to receive the load applied to the side sill (3) without deforming. Accordingly, the side sill inner is less likely to be deformed and crushed, and since the collision energy absorption ability can be maintained, the load transfer to the battery pack (5) can be reduced. As a result, the deformation of the battery pack (5) during a side collision can be suppressed and the battery pack (5) can be protected from damage, making it possible to create a safe vehicle.

[0021] In this embodiment, the floor cross member (7) is made of a metal plate with a tensile strength of 1180 MPa or higher, but if it is made of a metal plate with a tensile strength of less than 1180 MPa, it is easily deformed when a load is transmitted to the floor cross member, so the load cannot be sufficiently transmitted and the load transmitted to the battery pack (5) cannot be reduced.

[0022] Therefore, in this embodiment, the floor cross member (7) is made of a metal plate with a tensile strength of 1180 MPa or higher, and specifically, steel plates with a tensile strength of 1180 MPa, 1370 MPa, 1470 MPa, and 1760 MPa are exemplified.

[0023] In the vehicle body side structure (1), the end (7a) of the floor cross member (7) is in contact with the joint surface (3d) where the side sill inner (3a) and the side sill outer (3b) are joined, but is not joined. However, in the present invention, it is preferable that the end of the floor cross member is joined to the joint surface of the side sill inner and the side sill outer. Accordingly, in the event of a side collision, misalignment between the end of the floor cross member and the joint surface of the side sill inner and the side sill outer does not occur easily, and the load transfer path of the load input to the vehicle body (side sill) to the floor cross member can be maintained, making it easier to transfer the load to the floor cross member and further reducing the load transferred to the battery pack.

[0024] In addition, in the present invention, the floor cross member (7) has a groove shape extending in the vehicle width direction, having a bottom surface and a pair of vertical walls (not shown), and, for example as shown in FIG. 1, a wall face portion (7b) is formed at the tip of the end (7a) that is curved and continuous from the bottom surface (7a1), and it is preferable that the groove shape of the end (7a) of the floor cross member (7) is closed by the wall face portion (7b). Accordingly, the end (7a) of the floor cross member (7) is made difficult to crush, thereby preventing the vehicle body from being significantly deformed.

[0025] A specific example of a floor cross member (7) having a closed groove shape at the end (7a) in the vehicle width direction is shown in FIG. 3. In the floor cross member (7) shown in FIG. 3(a), the bottom surface (7a1), a pair of vertical walls (7a2), and a wall surface (7b) at the front end (7a) are integrated and continuous, so the groove shape is closed. In the floor cross member (7) shown in FIG. 3(b), because the vertical wall height (vehicle height direction height) is high, the groove-shaped bottom surface (7a1) and the wall surface (7b) at the front end are curved and continuous, but the groove-shaped bottom surface (7a1) and the pair of vertical walls (7a2) are not integrated and are not continuous. However, on both sides of the bottom surface (7a1) and the wall surface (7b), a welding margin (7c) is formed that is bent toward the vertical wall (7a2), and since the welding margin (7c) and the vertical wall (7a2) are joined by spot welding, the groove shape is closed.

[0026] Examples

[0027] Since a specific analysis was conducted to verify the functional effects of the vehicle body side structure related to the present invention, the results are described below.

[0028] In this embodiment, a side impact analysis was performed on a vehicle (101) having a vehicle body side structure (1) (inventive example) having a side sill (3), a battery pack (5), and a floor cross member (7) as shown in FIG. 1 in the above-described embodiment, by colliding a pole (103) from the outer side of the vehicle in the vehicle width direction as shown in FIG. 4. In addition, in the vehicle body side structure (1) in this embodiment, the battery pack (5) is supported by a battery frame assembly (11) formed on the outer side in the vehicle width direction as shown in FIG. 5(b). And, as shown in FIG. 5(b), the battery frame assembly (11) is composed of a plurality of steel sheet parts.

[0029] In the analysis of the side collision, the vehicle (101) was accelerated to 29 km / h in the vehicle width direction and collided with a rigid body pole (103) on the side of the vehicle (101). The pole collision position where the pole (103) collides with the vehicle (101) was set to the vehicle length direction position TL = 1916 mm. When the pole (103) collides with the side sill (3) on the side of the vehicle (101), the side sill (3) (see FIG. 1) is locally deformed and penetrates into the vehicle. Therefore, in this embodiment, the amount of deformation of the battery pack (5) and the load input to the battery pack (5) during the side collision process were evaluated.

[0030] Regarding the amount of deformation of the battery pack (5), as shown in FIG. 5(a), the length in the vehicle width direction of the battery pack (5) before and after deformation was measured at multiple positions in the vehicle length direction (positions indicated by arrows in FIG. 5(a)), and the difference between the before and after deformation was calculated. Meanwhile, regarding the load input to the battery pack (5), as shown in FIG. 5(b), the reaction force (contact reaction force) generated in the battery frame assembly (11) by contact of the connecting member (13) formed on the outer circumference in the vehicle width direction of the battery frame assembly (11) during the collision process was calculated.

[0031] In addition, in this embodiment, for the vehicle body side structure (21) (Comparative Example 1) shown in FIG. 6(b) and the vehicle body side structure (31) (Comparative Example 2) shown in FIG. 6(c) as comparison subjects, a side collision analysis of the vehicle shown in FIG. 4 was performed in the same manner as in the invention example, and the amount of deformation of the battery pack (5) and the load input to the battery pack (5) during the side collision process were evaluated.

[0032] The side body structure (21) related to Comparative Example 1 has the end (23a) in the width direction of the floor cross member (23) extended to cover the side sill inner (3a), but does not come into contact with the joint surface (3d) of the side sill inner (3a) and the side sill outer (3b).

[0033] The side body structure (31) related to Comparative Example 2 is such that the end (33a) in the width direction of the floor cross member (33) does not extend upward to the side sill inner (3a).

[0034] In Comparative Examples 1 and 2, the load input to the battery pack (5) side was calculated as the contact reaction force between the connecting member (13) and the battery frame assembly (11), just like in the inventive example.

[0035] FIG. 7 shows the results of the amount of deformation of the battery pack (5) in the inventive example, comparative example 1, and comparative example 2 when the pole collision position is set to the vehicle length direction position TL = 1916 mm. As shown in FIG. 7, compared to comparative example 2, where the end (33a) of the floor cross member (33) does not extend above the side sill inner (3a), the amount of deformation of the battery pack (5) in the inventive example and comparative example 1 is smaller. Furthermore, when comparing the inventive example and comparative example 1, the inventive example showed a smaller amount of deformation of the battery pack (5).

[0036] FIG. 8 shows the results of the contact reaction force obtained as the load input to the battery pack (5) during a side collision in which the pole collision position is set to the vehicle length direction position TL = 1916 mm in the inventive example, comparative example 1, and conventional example 2. As shown in FIG. 8, compared to comparative example 2 in which the end (33a) of the floor cross member (33) does not extend above the side sill inner (3a), the load input to the battery pack (5) in the inventive example and comparative example 1 is reduced. Furthermore, when comparing the inventive example and comparative example 1, the load input to the battery pack (5) in the inventive example was smaller.

[0037] In summary, according to the vehicle body side structure related to the present invention, in the event of a side collision, by transferring the load input to the vehicle to the floor cross member, the load input to the battery pack can be sufficiently reduced, thereby reducing the deformation of the battery pack and protecting the battery pack.

[0038] Industrial applicability

[0039] According to the present invention, in the event of a side collision of a vehicle body having a side sill and a battery pack and a floor cross member formed on the interior side of the vehicle width direction of the side sill, a vehicle body side structure can be provided that can protect the battery pack by reducing the load transmitted to the battery pack during the side collision of the vehicle body. Explanation of the symbols

[0040] 1 : Side body structure 3: Side Sill 3a: Side sill inner 3a1 : Ceiling panel (side) 3a2 : Vertical wall (top surface) 3a3 : Flange 3b : Side sill outer 3c : Top part 3d: Joint surface 5 : Battery pack 7 : Floor Cross Member 7a : end 7a1 : Bottom surface 7a2 : Vertical wall 7b : Wall part 7c : Welding margin 9 : Floor panel 11: Battery frame assembly 13: Connecting member 21: Body side structure 23: Floor Cross Member 23a : end 31: Side body structure 33: Floor Cross Member 33a : End

Claims

Claim 1 A side body side structure comprising: a side sill formed by joining at the upper and lower ends in the vehicle height direction, a side sill inner having a groove shape that opens toward the outer side in the vehicle width direction and extending in the front-rear direction of the vehicle body, having a roof plate and a pair of vertical walls, and a side sill outer having a groove shape that opens toward the inner side in the vehicle width direction; a battery pack disposed and formed at the lower part of the vehicle body in the vehicle width direction relative to the side sill; and a floor cross member disposed and formed extending in the vehicle width direction above the side sill in the vehicle width direction relative to the inner side in the vehicle width direction, wherein the floor cross member is made of a metal plate having a tensile strength of 1180 MPa or higher, and the end of the side sill outer side in the vehicle width direction does not come into contact with the roof plate which is the surface of the side sill inner in the vehicle width direction, and is disposed and formed to cover the upper surface of the side sill inner in the vehicle height direction, and the side sill inner and the side sill outer A side body structure that extends to and meets the joint surface at the upper end. Claim 2 A side body structure according to claim 1, wherein the floor cross member has a groove shape extending in the width direction of the vehicle, a wall portion is formed at its leading end that contacts the joint surface portion, and the groove shape at the end of the floor cross member is closed by the wall portion. Claim 3 A vehicle body side structure according to claim 1 or 2, wherein the end of the floor cross member is joined to the joint surface of the side sill inner and the side sill outer.

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