Vehicle body side structure

Abstract

This vehicle body side structure (1) is provided with: a collision energy absorbing member (11) provided in a convex shape toward the outside in the vehicle width direction on the outer peripheral side in the vehicle width direction of a battery pack (5); and a recessed portion (13) which is formed in the side sill (3) in a recessed shape so as to secure a space between the collision energy absorbing member (11) and the side sill (3), and which delays the timing of contact between the side sill (3) and the collision energy absorbing member (11) when a collision load is input to the side surface of the side sill (3). Thus, a collision load input to the side sill (3) is transmitted to the floor cross member (7) before the side sill (3) is in contact with the collision energy absorbing member (11), and after the side sill (3) is in contact with the collision energy absorbing member (11), the collision energy absorbing member (11) absorbs collision energy, thereby reducing the load transmitted to the battery pack (5).

Description

Technical Field

[0001] The present invention relates to an automotive body side structure of an electric vehicle or the like, which includes a battery pack on the vehicle inner side in the vehicle width direction relative to a side sill. Background Art

[0002] In recent years, especially in the automobile industry, due to environmental issues, the replacement from gas-engine cars to electric cars is being promoted. Electric cars and the like are equipped with a battery pack containing a large battery in the floor portion of the lower part of the vehicle body. Moreover, most batteries use lithium-based materials. If the battery pack is damaged and liquid leaks from the battery during a collision, there is a risk of fire, so a structure to protect the battery pack is required. As a structure to protect the battery pack, there is a lower longitudinal beam, and the battery pack is arranged between the lower longitudinal beams on both sides of the vehicle body.

[0003] Typically, the lower longitudinal beam of an electric vehicle, etc., for example, as disclosed in Patent Document 1, has an inner side that is straight and has no bumps and depressions, like the previous vehicle body. However, from the perspective of a structure that protects the battery pack, the shape of the lower longitudinal beam is very important. Therefore, for example, Patent Document 2 discloses the following technology: a lower longitudinal beam having a hat-shaped cross section, a hat-shaped section part, a cross section of the hat part perpendicular to the long side direction having a top portion, two vertical walls, and two flanges, wherein a plurality of groove portions extending in a direction perpendicular to the long side direction are provided on the vertical wall, thereby increasing the load required for deformation of the lower longitudinal beam during a side impact collision of the vehicle, thereby achieving a higher energy absorption efficiency and protecting the battery.

[0004] Patent Document 1: Japanese Patent No. 6928719

[0005] Patent Document 2: Japanese Patent No. 6703322

[0006] However, in the technology disclosed in Patent Document 2, multiple grooves are provided in the longitudinal wall of the cap component, so that if the collision load is input from the outside of the vehicle in the vehicle width direction, the longitudinal wall is easily deformed in a bellows-shaped manner. As a result, the deformation of the lower longitudinal beam toward the inside of the vehicle in the vehicle width direction increases, which will input a large load to the battery pack and cause it to deform, and there is a situation where the battery cannot be protected. Therefore, in the event of a side collision of an electric vehicle, etc., it is required to reduce the load and deformation input to the battery pack due to the deformation of the lower longitudinal beam. Summary of the invention

[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a vehicle body side structure capable of reducing the load and deformation input to a battery pack due to deformation of a side sill during a side collision of an electric vehicle or the like.

[0008] The vehicle body side structure of the present invention comprises: a lower longitudinal beam, which is arranged on the outer side of the vehicle body in the vehicle width direction and extends in the vehicle length direction; a battery pack, which is arranged at the lower part of the above-mentioned vehicle body on the inner side of the vehicle width direction relative to the lower longitudinal beam; and a floor cross member, which extends in the vehicle width direction and the end portion on the outer side of the vehicle in the vehicle width direction is connected to the above-mentioned lower longitudinal beam, wherein the steel plate used for the above-mentioned lower longitudinal beam has a tensile strength of 980MPa grade (MPa-class) or more, and the above-mentioned vehicle body side structure comprises: a collision energy absorption part (parts for impact energy absorption), which is provided in a convex shape toward the outer side of the vehicle in the vehicle width direction at the outer peripheral side of the above-mentioned battery pack in the vehicle width direction, and absorbs collision energy when a collision load (crushing load) is input from the outer side of the vehicle in the vehicle width direction to the above-mentioned lower longitudinal beam; and a recessed part (recessed The side member is provided with a concave shape that is recessed toward the vehicle outer side in the vehicle width direction on the vehicle inner side of the side member in the vehicle width direction in accordance with the convex shape of the collision energy absorbing component, so that a space is ensured between the collision energy absorbing component side and the side member. The collision energy absorbing component and the concave shape portion are provided along the entire length of the side member in the vehicle length direction or are provided at a portion in the vehicle length direction. When a collision load is input to the side member from the vehicle outer side in the vehicle width direction, a timing at which the side member contacts the collision energy absorbing component is delayed by the space between the side member and the battery pack side, so that the collision load input to the side member is transmitted to the floor cross member before the side member contacts the collision energy absorbing component. After the side member contacts the collision energy absorbing component, the collision energy is absorbed by the collision energy absorbing component, so that the load transmitted to the battery pack is reduced.

[0009] The concave portion may be formed in a region of the side sill that is less than 1 / 2 of the vehicle body height direction on the vehicle inner side in the vehicle width direction.

[0010] The depth of the concave portion in the vehicle width direction may be 50 mm or less.

[0011] According to the present invention, in a side collision in which a collision load is input to the side beam from the vehicle width direction outer side, the timing of the side beam contacting the battery pack can be delayed by the space ensured between the collision energy absorbing member and the concave portion formed on the side beam, thereby transferring the load to the floor cross member before the side beam contacts the collision energy absorbing member, and after the side collision occurs and the side beam contacts the collision energy absorbing member, the collision energy absorbing member can absorb the collision energy. As a result, the load input to the battery pack can be reduced, deformation can be suppressed, and the battery pack can be protected from damage, thereby manufacturing a safe vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The following are diagrams for explaining the vehicle body side structure according to the embodiment of the present invention.

[0013] Figure 2 This is a diagram for explaining a side collision of a vehicle body that is an analysis target in the embodiment.

[0014] Figure 3 The figure shows the evaluation method of the deformation amount of the battery pack and the input load to the battery pack in the embodiment ((a) is the evaluation position of the deformation amount of the battery pack, and (b) is the input load to the battery pack).

[0015] Figure 4 It is a cross-sectional view of a vehicle body side structure of a comparative example serving as a comparison target in the embodiment.

[0016] Figure 5 It is a diagram showing a vehicle body side structure of a conventional example serving as a comparative object in the embodiment.

[0017] Figure 6 This is a graph showing the results of the deformation amount of the battery pack in the example.

[0018] Figure 7 This is a graph showing the results of contact reaction force obtained as input load to the battery pack in the examples.

[0019] Figure 8 The figures show deformation states of vehicle body side structures of conventional examples and inventive examples during a side collision in the embodiments ((a) conventional example, (b) inventive example). DETAILED DESCRIPTION

[0020] like Figure 1 As shown, the vehicle body side structure 1 of the embodiment of the present invention comprises: a lower longitudinal beam 3 extending in the vehicle length direction; a battery pack 5 arranged on the inner side of the vehicle in the vehicle width direction relative to the lower longitudinal beam 3; a floor cross member 7 extending in the vehicle width direction and connected to the lower longitudinal beam 3 at the end 7a on the outer side of the vehicle in the vehicle width direction; and a ground side cross member 9. The vehicle body side structure 1 of the embodiment of the present invention is constructed such that the steel plate used for the lower longitudinal beam 3 has a tensile strength of 980 MPa or above, and the vehicle body side structure 1 has a collision energy absorbing component 11 arranged on the outer peripheral side of the battery pack 5 in the vehicle width direction, and a concave portion 13 formed on the inner side of the lower longitudinal beam 3 in the vehicle width direction. In the following, based on Figure 1 A vehicle body side structure 1 according to the present embodiment will be described. In the present specification and the drawings, elements having the same functional configuration are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0021] like Figure 1 As shown, the side sill 3 includes: a side sill inner 3a having a groove shape opening toward the vehicle outer side in the vehicle width direction; and a side sill outer 3b having a groove shape opening toward the vehicle inner side in the vehicle width direction. The side sill inner 3a and the side sill outer 3b have their opening sides facing each other and their ends on the upper side of the vehicle body and the ends on the lower side of the vehicle body are respectively joined to form a closed cross section structure.

[0022] The battery pack 5 has a battery cell (not shown) mounted therein and includes a battery pack upper part 5a and a battery pack lower part 5b. The battery pack 5 is supported by a battery frame assembly 15 disposed on the outer peripheral side in the vehicle width direction. Figure 1 As shown, the battery frame assembly 15 is composed of a plurality of steel sheet parts.

[0023] The floor cross member 7 is disposed on the upper side of the vehicle body of the battery pack 5 , and an end portion 7 a on the outer side in the vehicle width direction is connected to an upper portion of the side sill inner member 3 a .

[0024] The ground-side cross member 9 is disposed on the vehicle body lower side of the battery pack 5 , and an end portion 9 a on the vehicle outer side in the vehicle width direction is fastened to the lower portion of the side member 3 by a bolt 17 .

[0025] The collision energy absorbing member 11 is provided in a convex shape toward the outer side in the vehicle width direction on the outer peripheral side of the battery pack 5 , and absorbs collision energy when a collision load is input to the side sill 3 from the outer side in the vehicle width direction.

[0026] The concave portion 13 is formed on the vehicle widthwise inner side of the side sill 3 to be concave toward the vehicle widthwise outer side to match the convex shape of the impact energy absorbing member 11 . Thus, a predetermined space is secured between the impact energy absorbing member 11 and the side sill 3 .

[0027] Furthermore, when the collision load is input to the side sill 3 from the vehicle outer side in the vehicle width direction, the vehicle body side structure 1 delays the timing of the side sill 3 contacting the collision energy absorbing member 11 by ensuring a space between the collision energy absorbing member 11 and the concave portion 13 of the side sill 3. Furthermore, before the side sill contacts the collision energy absorbing member, the collision load input to the side sill 3 is transmitted to the floor cross member 7 and the ground side cross member 9, and after the side sill 3 contacts the collision energy absorbing member 11, the collision energy is absorbed by the collision energy absorbing member 11, thereby reducing the load transmitted to the battery pack 5. As a result, the deformation of the battery pack 5 can be suppressed, and the batteries in the battery pack 5 can be protected.

[0028] The concave portion 13 may be formed in a region of the side sill 3 that is less than 1 / 2 of the vehicle height direction on the vehicle inner side in the vehicle width direction ( Figure 1 Thus, even if the concave portion 13 is formed, the function of the side sill 3 is not impaired, and a space can be ensured between the side sill 3 and the collision energy absorbing member 11.

[0029] In addition, the depth of the concave portion 13 in the vehicle width direction may be 50 mm or less. Thus, the concave portion 13 can be formed in the side sill inner member 3 a while ensuring the function of the side sill 3 .

[0030] The collision energy absorbing member 11 and the concave portion 13 may be provided along the entire length of the side sill 3 or may be provided in a portion thereof. When provided in a portion thereof, it may be provided in a region where a pole enters the entire length.

[0031] In addition, in the vehicle body side structure of the present invention, from the viewpoint of ensuring the functions of the lower side sill (stiffness, impact energy absorption capacity, etc.), the tensile strength of the steel plate used for the lower side sill is set to 980 MPa level or above. For example, steel plates with tensile strengths of 980 MPa level, 1180 MPa level, 1370 MPa level, 1470 MPa level, and 1760 MPa level can be used.

[0032] like Figure 1 As shown, the vehicle body side structure 1 of the present embodiment includes a battery frame assembly 15, and the collision energy absorbing member 11 is provided on the vehicle width direction outer peripheral surface of the battery frame assembly 15. However, the vehicle body side structure of the present invention may not include a battery frame assembly, in which case the collision energy absorbing member only needs to be provided on the vehicle width direction outer peripheral surface of the battery pack.

[0033] In addition, the vehicle body side structure 1 of the present embodiment is provided with a floor cross member 7 on the upper side of the battery pack 5 and a ground side cross member 9 on the lower side, but the present invention may also be provided with only a floor cross member. In this case, when a collision load is input from the outer side of the lower side member in the vehicle width direction, the collision load input to the lower side member is dispersed to the floor cross member before the lower side member contacts the collision energy absorbing member, and the collision energy is absorbed by the collision energy absorbing member after the lower side member contacts the collision energy absorbing member. Therefore, the load transmitted to the battery pack can be reduced, and the deformation of the battery pack can be suppressed.

[0034] Example

[0035] Since a specific analysis was performed to verify the effects of the vehicle body side structure of the present invention, the results will be described below.

[0036] In this embodiment, if Figure 2 As shown, a side impact analysis (side impact analysis) was performed on a vehicle 101 having a vehicle body side structure 1 (invention example) having a rod 103 colliding from the outside of the vehicle in the vehicle width direction. The vehicle body side structure 1 has the Figure 1 The lower longitudinal beam 3, battery pack 5, floor cross member 7 and ground side cross member 9 shown in the figure have a collision energy absorbing component 11 and a concave portion 13 (depth 20 mm). Four sets of floor cross members 7 and ground side cross members 9 are arranged at corresponding positions in the vehicle height direction at intervals of 348 mm in the vehicle length direction within a range of 1044 mm. Figure 6 In addition, a collision energy absorbing member 11 and a concave portion 13 are provided along the vehicle length direction of the lower longitudinal beam 3 over the range where the floor cross member 7 and the ground side cross member 9 are arranged ( Figure 6 position of “A” in the image).

[0037] In the side collision analysis, the vehicle 101 is accelerated to 29 km / h in the vehicle width direction, and the rod 103 as a rigid body collides with the side of the vehicle 101. Then, when the rod 103 collides with the side of the vehicle 101, the side sill 3 (see Figure 1) is partially deformed and penetrates into the vehicle interior. In addition, in this embodiment, the deformation amount of the battery pack 5 during the side collision and the load input to the battery pack 5 side are evaluated.

[0038] Regarding the battery pack 5 (refer to Figure 1 ) deformation, such as Figure 3 As shown in (a), at multiple positions in the vehicle length direction (in Figure 3 The lengths of the battery pack 5 in the vehicle width direction before and after deformation were measured at the position indicated by the arrow in (a), and the difference between before and after deformation was obtained. On the other hand, regarding the load input to the battery pack 5 side, as shown in FIG. Figure 3 As shown in (b), the reaction force (contact reaction force) generated in the battery frame assembly 15 due to the contact between the collision energy absorbing member 11 and the side sill inner member 3a during the collision is obtained.

[0039] In this embodiment, as a comparison object, Figure 4 The vehicle body side structure 21 (conventional example) shown in FIG. Figure 5 The vehicle body side structure 31 (comparative example) shown in FIG. 1 is also carried out in the same manner as in the invention example. Figure 2 The side impact test shown evaluates the amount of deformation of the battery pack 5 and the load input to the battery pack 5 during the side impact.

[0040] like Figure 4 As shown, the vehicle body side structure 21 of the conventional example includes a side sill 23 including a side sill inner member 23 a and a side sill outer member 23 b , and the lower portion of the side sill 23 is connected to the battery frame assembly 15 via an aluminum connecting member 25 .

[0041] On the other hand, Figure 5 As shown, the vehicle body side structure 31 of the comparative example includes a side sill 33 including a side sill inner member 33 a and a side sill outer member 33 b , and although the collision energy absorbing member 11 is provided in the battery frame assembly 15 , no concave portion is formed on the vehicle inner side of the side sill 33 .

[0042] The deformation amounts of the battery pack 5 in the conventional example and the comparative example were obtained in the same manner as in the inventive example (refer to Figure 3 ). In contrast, for the load input to the battery pack 5 side in the conventional example, the contact reaction force between the connecting member 25 and the battery frame assembly 15 is calculated, and for the load input to the battery pack 5 in the comparative example, the contact reaction force between the battery frame assembly 15 and the battery frame assembly 15 generated by the contact between the collision energy absorbing member 11 and the lower longitudinal beam inner member 33a is calculated in the same manner as in the inventive example.

[0043] Figure 6The results of analyzing the deformation amount of the battery pack 5 at each position in the vehicle length direction in the inventive example, the conventional example, and the comparative example are shown. Figure 6 A in FIG. 1 shows the position in the vehicle length direction where the floor cross member 7 and the ground side cross member 9 are arranged. Figure 6 The results are obtained when the position where the rod 103 as a rigid body collides with the side of the vehicle 101 is set to the position in the vehicle length direction (=1568 mm) where the floor cross member 7, the ground side cross member 9, the collision energy absorbing member 11 and the concave portion 13 are arranged, and the diameter of the rod 103 is set to 254 mm.

[0044] The deformation amount of the battery pack 5 is smaller in the invention example than in the conventional example and the comparative example at any position in the vehicle length direction. Figure 6 The average deformation amount of the battery pack 5 of A) is 0.76 mm in the prior art, 0.42 mm in the comparative example, and 0.37 mm in the present invention, which is 44% lower than that in the prior art and 13% lower than that in the comparative example. Figure 6 The maximum value of the deformation amount of the battery pack 5 (other than A) is 4.73 mm in the prior art example, 1.92 mm in the comparative example, and 1.41 mm in the example of the present invention, which is a 70% reduction compared with the prior art example and a 27% reduction compared with the comparative example.

[0045] Figure 7 The results of analysis of the load input to the battery pack 5 at a position of 1568 mm in the vehicle length direction where the floor cross member 7 and the ground-side cross member 9 are arranged are shown.

[0046] The time for the load input to the battery pack 5 side in the inventive example to reach the peak value is 0.0382 seconds, which is 0.012 seconds slower than 0.0262 seconds in the prior art example and 0.0380 seconds in the comparative example, and 0.0002 seconds slower, respectively. As a result, the peak value of the load input to the battery pack 5 side in the inventive example is 92 kN, which is significantly lower than the prior art example (peak value: 266 kN) and the comparative example (peak value: 179 kN) (reduced by 65% ​​relative to the prior art example and 49% relative to the comparative example).

[0047] Figure 8 The deformation states of the vehicle body side structure 21 of the conventional example and the vehicle body side structure 1 of the invention example at the start of the side collision of the vehicle 101 (0.0 s) and during the collision (0.15 s and 0.2 s from the start of the collision) are shown.

[0048] In the existing example, Figure 8As shown in (a), the connecting member 25 connected to the battery pack 5 deformed at 0.015s, and the connecting member 25 was not completely crushed at 0.02s and retained the shape at the beginning of the collision. Therefore, it is known that the load is transmitted to the battery pack 5 and deformed.

[0049] In contrast, in the invention example, Figure 8 As shown in (b), the concave portion 13 is formed on the side sill 3, so that the side sill 3 does not contact the collision energy absorbing member 11 at 0.015s, and the floor cross member 7 and the ground side cross member 9 are connected to the upper and lower parts of the side sill 3. This suggests that the load input to the side sill is transmitted to the floor cross member 7 and the ground side cross member 9, and the collision energy is absorbed.

[0050] In addition, if a side collision occurs, the collision energy absorbing member 11 is almost crushed 0.02 seconds after the lower side sill 3 contacts the collision energy absorbing member 11, but the battery frame assembly 15 does not deform. Therefore, it can be seen that the collision energy is absorbed by the collision energy absorbing member 11, thereby reducing the load input to the battery pack 5 (battery frame assembly 15), and the deformation of the battery pack 5 can be suppressed.

[0051] As described above, according to the vehicle body side structure of the present invention, the timing of the side beam contacting the battery pack is delayed by ensuring a space between the collision energy absorbing member and the side beam, so that the load of the floor cross member can be transmitted before the side beam contacts the collision energy absorbing member, and after the side beam contacts the collision energy absorbing member during a side collision, the collision energy absorbing member can absorb the collision energy. Thus, it is shown that the load input to the battery pack is reduced, deformation is suppressed, and the battery pack is protected from damage, and it is suitable as a vehicle body side structure of electric vehicles, etc.

[0052] Industrial Applicability

[0053] According to the present invention, it is possible to provide a vehicle body side structure capable of reducing the load and deformation input to a battery pack due to deformation of a side sill during a side collision of an electric vehicle or the like.

[0054] Description of Reference Numerals

[0055] 1…body side structure; 3…lower beam; 3a…lower beam inner part; 3b…lower beam outer part; 5…battery pack; 5a…battery pack upper part; 5b…battery pack lower part; 7…floor cross beam; 7a…end; 9…ground side cross beam; 9a…end; 11…collision energy absorbing part; 13…concave part; 15…battery frame assembly; 17…bolt; 21…body side structure; 23…lower beam; 23a…lower beam inner part; 23b…lower beam outer part; 25…connecting part; 31…body side structure; 33…lower beam; 33a…lower beam inner part; 33b…lower beam outer part; 101…vehicle; 103…pole.

Claims

1. A vehicle body side structure, comprising: a lower longitudinal beam, the lower longitudinal beam being arranged on the vehicle outer side in the vehicle width direction of the vehicle body and extending in the vehicle length direction; a battery pack, the battery pack being arranged at the lower portion of the vehicle body on the vehicle inner side in the vehicle width direction relative to the lower longitudinal beam; and a floor cross member, the floor cross member extending in the vehicle width direction and having an end portion on the vehicle outer side in the vehicle width direction connected to the lower longitudinal beam, The vehicle body side structure is characterized in that: The steel plate used for the lower longitudinal beam has a tensile strength of 980 MPa or above. The vehicle body side structure comprises: a collision energy absorbing member, the collision energy absorbing member being provided in a convex shape toward the outer side of the vehicle in the vehicle width direction at the outer peripheral side of the battery pack in the vehicle width direction, and absorbing collision energy when a collision load is input to the lower side member from the outer side of the vehicle in the vehicle width direction; and a concave portion, the concave portion being formed on the vehicle width direction vehicle inner side of the side sill in a concave shape recessed toward the vehicle width direction vehicle outer side in accordance with the convex shape of the collision energy absorbing member in such a manner as to ensure a space between the collision energy absorbing member side and the side sill, The collision energy absorbing member and the concave portion are provided along the entire length of the side sill in the vehicle length direction or are provided in a portion of the side sill in the vehicle length direction. When a collision load is input to the lower side beam from the outer side of the vehicle in the vehicle width direction, the timing at which the lower side beam contacts the collision energy absorbing component is delayed by the space between the lower side beam and the battery pack side, thereby transmitting the collision load input to the lower side beam to the floor cross member before the lower side beam contacts the collision energy absorbing component, and absorbing the collision energy after the lower side beam contacts the collision energy absorbing component, thereby reducing the load transmitted to the battery pack.

2. The vehicle body side structure according to claim 1, characterized in that: The concave portion is formed in a region of the side sill that is less than ½ of the vehicle body height direction on the vehicle inner side in the vehicle width direction.

3. The vehicle body side structure according to claim 1 or 2, characterized in that: The depth of the concave portion in the vehicle width direction is 50 mm or less.

Images