Vehicle lower part structure

Abstract

To provide a vehicle lower part structure capable of reducing an impact load input to a battery upon a side collision of a vehicle.SOLUTION: In an EA part 42, rigidity is lower on an outer side in a vehicle width direction relative to a fastening part 32 where a battery pack 20 is fastened to a rocker 16 than on an inner side in the vehicle width direction. Thereby, upon a side collision of a vehicle 12, an absorption amount of impact energy can be increased on the outer side in the vehicle width direction in the EA part 42, and deformation can be suppressed on the inner side in the vehicle width direction in the EA part 42. In addition, the fastening part 32 has high rigidity, so that sufficient reaction force against plastic deformation of the rocker 16 and the EA part 42 can be obtained by the fastening part 32. Thus, collapse is likely to occur on the outer side in the vehicle width direction in the EA part 42, and the impact energy can be absorbed more effectively. As a result, an impact load input to the battery pack 20 can be reduced upon the side collision of the vehicle 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle undercarriage. [Background technology]

[0002] Patent Document 1 below discloses a technology related to a vehicle undercarriage structure that mounts a battery module. In this prior art, a battery side frame provided on the outer side of the battery module in the vehicle width direction is connected to the lower side of a rocker. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-133046 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described prior art, in the event of a side collision of the vehicle (hereinafter referred to as "a vehicle side collision"), the side collision load (impact load) input to the rocker may be input to the battery side via the battery side frame.

[0005] SUMMARY OF THE INVENTION In consideration of the above, an object of the present invention is to provide a vehicle underbody structure that can reduce the impact load input to a battery in the event of a side collision of the vehicle. [Means for solving the problem]

[0006] The vehicle undercarriage structure of the invention described in claim 1 comprises a rocker extending in the longitudinal direction of the vehicle on the outer side of the vehicle width direction of the passenger compartment, an impact absorbing section constituted by a plurality of energy absorbing sections arranged along the vehicle width direction within the rocker, and a battery arranged under the vehicle, wherein the portion of the impact absorbing section located outside the vehicle width direction of the fastening section where the battery is fastened to the rocker has lower rigidity than the portion located inside the vehicle width direction of the fastening section.

[0007] The vehicle undercarriage structure according to the invention of claim 1 includes a rocker, an impact absorbing part, and a battery. The rocker extends in the longitudinal direction of the vehicle on the outer side of the vehicle width direction of the passenger compartment, and the impact absorbing part is composed of a plurality of energy absorbing parts arranged along the vehicle width direction within the rocker. The battery is disposed under the vehicle.

[0008] In the present invention, the portion of the impact absorbing portion located on the outer side in the vehicle width direction of the fastening portion where the battery is fastened to the rocker has lower rigidity than the portion located on the inner side in the vehicle width direction of the fastening portion. As a result, in the event of a side collision of the vehicle, the amount of impact energy absorbed on the outer side in the vehicle width direction of the impact absorbing portion can be increased, and deformation can be suppressed on the inner side in the vehicle width direction of the impact absorbing portion.

[0009] Generally, the fastening portion where the battery is fastened to the rocker is made highly rigid. Therefore, in the event of a side collision, the fastening portion can generate sufficient reaction force against plastic deformation of the rocker and EA portion, making the impact absorbing portion more susceptible to crushing on the outer side of the fastening portion in the vehicle width direction. Therefore, the outer side of the impact absorbing portion in the vehicle width direction can more effectively absorb impact energy.

[0010] The vehicle underbody structure according to the invention recited in claim 2 is the vehicle underbody structure according to the invention recited in claim 1, wherein the impact absorbing portion includes an outer impact absorbing portion provided on the outer side in the vehicle width direction within the rocker, and an inner impact absorbing portion provided on the inner side in the vehicle width direction of the outer impact absorbing portion.

[0011] In the vehicle undercarriage structure according to the invention recited in claim 2, the impact absorbing parts are configured to include an outer impact absorbing part and an inner impact absorbing part. The outer impact absorbing part is provided on the outer side in the vehicle width direction within the rocker, and the inner impact absorbing part is provided on the inner side in the vehicle width direction of the outer impact absorbing part.

[0012] The outer impact absorbing portion has lower rigidity than the inner impact absorbing portion, and is able to absorb a greater amount of impact energy than the inner impact absorbing portion in the event of a side collision of the vehicle. On the other hand, the inner impact absorbing portion has higher rigidity than the outer impact absorbing portion, and is able to suppress deformation in the event of a side collision of the vehicle, and is able to protect the vehicle interior and the battery located inside the pair of left and right rockers.

[0013] The vehicle underbody structure according to the invention recited in claim 3 is the vehicle underbody structure according to the invention recited in claim 2, wherein the outer impact absorbing portion and the inner impact absorbing portion are integrally formed.

[0014] In the vehicle underbody structure according to the invention recited in claim 3, the outer impact absorbing part and the inner impact absorbing part are integrally formed. This includes cases where the outer impact absorbing part and the inner impact absorbing part are integrally molded, in which case the number of parts can be reduced.

[0015] The vehicle underbody structure of the invention described in claim 4 is the vehicle underbody structure of the invention described in claim 1, in which the impact absorbing portion is made up of multiple members with different rigidities, which are joined together to form an integrated unit.

[0016] In the vehicle undercarriage structure according to the invention of claim 4, the impact absorbing part is made up of a plurality of members with different rigidities, which are joined together to form an integrated unit, thereby improving the degree of freedom in design. The "joining" may be performed by fitting, welding, adhesion, etc.

[0017] A vehicle underbody structure according to the invention recited in claim 5 is the vehicle underbody structure according to the invention recited in claim 1, wherein the fastening portion is provided on a lower wall portion of the rocker.

[0018] In the vehicle undercarriage structure according to the invention described in claim 5, the fastening portion is provided on the lower wall of the rocker, which makes it possible to suppress the occurrence of stress concentration on the battery pack via the fastening portion in the event of a side collision of the vehicle, compared to when the fastening portion is provided on the side wall of the rocker. [Effects of the Invention]

[0019] As described above, the vehicle underbody structure according to the present invention can reduce the impact load input to the battery in the event of a side collision of the vehicle. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is an enlarged cross-sectional view of a main part of a vehicle to which the vehicle undercarriage structure according to the first embodiment is applied; [Figure 2] 1 is an enlarged cross-sectional view of a main part showing a first modified example of a vehicle to which the vehicle undercarriage structure according to the first embodiment is applied. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] A vehicle underbody structure according to an embodiment of the present invention will be described with reference to the drawings. Note that the arrows UP and RH shown as appropriate in each drawing indicate the upward and rightward directions, respectively, of a vehicle to which the vehicle underbody structure according to this embodiment is applied. Hereinafter, when the directions of front-rear, left-right, and up-down are simply used in the description, they will indicate front-rear in the vehicle front-rear direction, left-right in the vehicle left-right direction (vehicle width direction), and up-down in the vehicle up-down direction, unless otherwise specified. Also, in each drawing, some components and some symbols may be omitted to make the drawings easier to understand.

[0022] (Vehicle undercarriage configuration) First, the configuration of a vehicle underbody structure according to an embodiment of the present invention will be described.

[0023] 1, a vehicle (vehicle body) 12 to which a vehicle undercarriage 10 according to an embodiment of the present invention is applied includes a pair of left and right rockers 16 that each form a vehicle frame and extend along the front-to-rear direction of the vehicle at the lower ends of both ends in the vehicle width direction of a passenger compartment 14. Although not shown, a front cross member (not shown) is provided at the front ends of the pair of left and right rockers 16 along the vehicle width direction, and a rear cross member (not shown) is provided at the rear ends of the pair of left and right rockers 16 along the vehicle width direction.

[0024] The vehicle 12 according to this embodiment is an electric vehicle (BEV) that runs using the driving force of an electric motor (not shown), and a battery pack (battery) 20 that houses a plurality of battery cells 18 that supply driving power to the electric motor is provided under the vehicle 12. The vehicle 12 may also be a plug-in hybrid vehicle (PHEV), a fuel cell electric vehicle (FCEV), or the like.

[0025] The battery pack 20 is made of a light metal such as an aluminum alloy and includes a box-shaped battery case 22 that is rectangular in plan view with its longitudinal direction aligned with the front-to-rear direction of the vehicle and has an opening at the top. Note that the battery case 22 may be made of a resin material other than metal, such as carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP).

[0026] The battery case 22, for example, with the plurality of battery cells 18 housed therein, is closed by a cover 24 having a rectangular plate shape in a plan view. The cover 24 is made of a light metal such as an aluminum alloy, has a plate shape with its thickness direction in the vertical direction of the vehicle, and is integrated with the battery case 22 by welding or the like. The cover 24 forms a floor that constitutes the floor portion of the passenger compartment 14, and although not shown, a floor cross member is disposed on top of the cover 24 along the vehicle width direction so as to span between the pair of left and right rockers 16.

[0027] On the other hand, the battery case 22 is configured to include, for example, a bottom wall 26 and side walls 28 erected from the outer edge of the bottom wall 26. The bottom wall 26 extends outward in the vehicle width direction beyond the side walls 28 and is fastened to the lower wall portion 16A of the rocker 16 via fastening portions 32 such as bolts 30. In this way, the battery case 22 is supported by the rocker 16.

[0028] In this embodiment, the rocker 16 is configured to include an outer portion 36 and an inner portion 38, and the outer portion 36 and the inner portion 38 form a closed cross-sectional portion 40. An EA portion (impact absorbing portion) 42 is disposed (placed) within the closed cross-sectional portion 40.

[0029] The closed cross-sectional portion 40 has a substantially hexagonal cross-sectional shape when cut along the vehicle width direction and the vehicle vertical direction, and is formed so that the dimension in the vehicle vertical direction is longer than the dimension in the vehicle width direction. Note that the cross-sectional shape of the closed cross-sectional portion 40 is not particularly limited.

[0030] 1 shows the rocker 16 in a state where the outer portion 36 and the inner portion 38 are integrally molded, it goes without saying that the outer portion 36 and the inner portion 38 may be formed as separate members and joined together to form an integrated unit. Furthermore, the EA portion 42 may be connected to the rocker 16 via a connecting portion (not shown) such as a bolt, or may be integrally molded with the rocker 16 by extrusion molding or the like.

[0031] In this embodiment, the EA portion 42 is configured by a plurality of energy absorbing portions 44, each having a substantially rectangular closed cross-sectional shape when cut along the vehicle width direction and the vehicle vertical direction. In this embodiment, the substantially central portion of the EA portion 42 in the vehicle vertical direction is at substantially the same height as the position of the cover 24.

[0032] That is, the upper side of the EA section 42 overlaps with the interior of the vehicle compartment 14 in a side view of the vehicle, and the lower side of the EA section 42 overlaps with the upper part of the battery pack 20 in a side view of the vehicle. Note that, if a floor cross member is provided in the vehicle compartment 14, the upper side of the EA section 42 overlaps with the floor cross member in a side view of the vehicle.

[0033] In this embodiment, the EA portion 42 is formed from a metal such as iron or an aluminum alloy, or from carbon fiber reinforced plastic (CFRP), and is configured to include a low-rigidity portion (outer impact absorbing portion) 46 provided on the outer side in the vehicle width direction, and a high-rigidity portion (inner impact absorbing portion) 48 provided on the inner side in the vehicle width direction. Note that, for ease of viewing, the low-rigidity portion 46 is indicated by hatching, and the high-rigidity portion 48 is indicated by cross-hatching.

[0034] In this embodiment, for example, the low rigidity portion 46 is formed to have a thinner plate thickness than the high rigidity portion 48, and has lower rigidity than the high rigidity portion 48. Note that the term "low rigidity" here is used for convenience in comparison with the "high rigidity portion," and the rigidity that is the original function of the EA portion 42 is guaranteed.

[0035] Furthermore, the low-rigidity portion 46 and the high-rigidity portion 48 may be integrally molded or may be formed separately. If the low-rigidity portion 46 and the high-rigidity portion 48 are formed separately, the low-rigidity portion 46 and the high-rigidity portion 48 will be integrated (formed integrally) by joining them by welding, melting, fastening, fitting, or the like depending on the material.

[0036] In this embodiment, the low rigidity portions 46 are configured in two rows x three pieces, and the high rigidity portions 48 are configured in one row x three pieces. The fastening portion 32 is provided below the high rigidity portion 48. That is, in this embodiment, the low rigidity portions 46 are provided in portions located outward in the vehicle width direction from the fastening portion 32, and the high rigidity portions 48 are provided in portions located inward in the vehicle width direction from the fastening portion 32.

[0037] (Action and effect of vehicle undercarriage structure) Next, the operation and effects of the vehicle underbody structure according to this embodiment will be described.

[0038] 1, in this embodiment, a vehicle undercarriage 10 is provided with a rocker 16, an EA section 42, and a battery pack 20. The rocker 16 extends in the vehicle front-rear direction on the outer side of the vehicle width direction of the passenger compartment 14, and the EA section 42 is made up of a plurality of energy absorption sections 44 arranged along the vehicle width direction within the rocker 16. The battery pack 20 is disposed under the vehicle.

[0039] In this embodiment, the EA section 42 has a portion located on the outer side in the vehicle width direction of the fastening portion 32 where the battery pack 20 is fastened to the rocker 16, which has lower rigidity than a portion located on the inner side in the vehicle width direction of the fastening portion 32. As a result, in this embodiment, in the event of a side collision of the vehicle 12, it is possible to increase the amount of impact energy absorbed at the outer side in the vehicle width direction of the EA section 42, and also to suppress deformation at the inner side in the vehicle width direction of the EA section 42.

[0040] Generally, the fastening portion 32 of the battery pack 20 has high rigidity, and therefore, in the event of a side collision of the vehicle 12, the fastening portion 32 can generate a sufficient reaction force against plastic deformation of the rocker 16 and the EA portion 42. Therefore, in the event of a side collision of the vehicle 12, the EA portion 42 is more likely to be crushed on the outer side in the vehicle width direction than the fastening portion 32, and impact energy can be absorbed more effectively. As a result, in this embodiment, it is possible to reduce the impact load input to the battery pack 20 in the event of a side collision of the vehicle 12.

[0041] To specifically describe the configuration of the EA section 42 in this embodiment, the EA section 42 is made up of a plurality of energy absorbing sections 44 each having a substantially rectangular closed cross-sectional shape, and the plate thickness of each energy absorbing section 44 is changed to form low rigidity sections 46 and high rigidity sections 48. The low rigidity sections 46 having a relatively thin plate thickness are provided on the outer side in the vehicle width direction, and the high rigidity sections 48 having a relatively thick plate thickness are provided on the inner side in the vehicle width direction.

[0042] The low rigidity portion 46 has lower rigidity than the high rigidity portion 48, and therefore can absorb a greater amount of impact energy than the high rigidity portion 48. On the other hand, the high rigidity portion 48 has higher rigidity than the low rigidity portion 46, and therefore in this embodiment, deformation can be suppressed during a side collision of the vehicle 12, and the interior of the vehicle compartment 14 and the battery pack 20 can be protected.

[0043] In this embodiment, the rigidity of the low-rigidity portion 46 and the high-rigidity portion 48 is changed by changing the plate thickness, so that the low-rigidity portion 46 and the high-rigidity portion 48 can be integrally molded. By integrally molding the low-rigidity portion 46 and the high-rigidity portion 48 in this way, the number of parts can be reduced.

[0044] Furthermore, in this embodiment, the fastening portion 32 is provided on the bottom wall portion 16A of the locker 16. As a result, although not shown, the gap between the locker 16 and the battery pack 20 can be made smaller than when the fastening portion 32 is provided on the side wall portion of the locker 16. In other words, in this embodiment, the battery pack 20 can be made larger by the amount that the gap can be made smaller, and the battery capacity can be increased accordingly.

[0045] Furthermore, as a comparative example (not shown), if a fastening portion 32 is provided between the rocker 16 and the battery pack 20, stress may be concentrated on the battery pack 20 via the fastening portion 32 during a side collision of the vehicle 12. On the other hand, in this embodiment, the battery pack 20 is housed between the left and right rockers 16, so it is possible to suppress stress concentration on the battery pack via the fastening portion 32 during a side collision of the vehicle 12. In other words, in this embodiment, it is possible to protect the battery pack 20 during a side collision of the vehicle 12.

[0046] In addition, in this embodiment, the approximate center of the EA section 42 in the vehicle up-down direction is at approximately the same height as the position of the cover 24. In other words, the upper side of the EA section 42 overlaps with the interior of the passenger compartment 14 in a side view of the vehicle, and the lower side of the EA section 42 overlaps with the battery pack 20 in a side view of the vehicle. Therefore, in this embodiment, it is possible to protect the interior of the passenger compartment 14 and the battery pack 20 in the event of a side collision of the vehicle 12.

[0047] In the present embodiment, the rigidity of the low-rigidity portion 46 and the high-rigidity portion 48 in the EA portion 42 is changed by changing the plate thickness, but this is not limitative, as long as the rigidity of the low-rigidity portion 46 is lower than that of the high-rigidity portion 48. Therefore, the low-rigidity portion 46 and the high-rigidity portion 48 do not necessarily have to be integrally molded. In other words, the low-rigidity portion 46 and the high-rigidity portion 48 may be formed separately.

[0048] For example, when the low-rigidity portion 46 and the high-rigidity portion 48 are formed separately from materials with different rigidities, they are joined together by welding, melting, fastening, fitting, or the like depending on the material, thereby integrating the low-rigidity portion 46 and the high-rigidity portion 48. In this way, forming the low-rigidity portion 46 and the high-rigidity portion 48 separately improves the degree of freedom in design compared to when the two are integrally molded.

[0049] In addition, in order to improve the rigidity of the high-rigidity portion 48 compared to the low-rigidity portion 46, reinforcing portions or reinforcing members such as diagonal braces may be used in the energy absorbing portion 44. Furthermore, the shape of the energy absorbing portion 44 itself is not limited to a substantially rectangular shape, and may be a triangular or hexagonal shape.

[0050] (Modification of this embodiment) 1, the energy absorption sections 44 of the EA section 42 are arranged in 3 rows x 3 along the vehicle up-down direction and vehicle width direction, with the upper sides of the EA sections 42 overlapping with the interior of the vehicle compartment 14 in a side view of the vehicle, and the lower sides of the EA sections 42 overlapping with the upper part of the battery pack 20 in a side view of the vehicle. However, the arrangement of the EA sections 42 is not limited to this.

[0051] 2, in a modified example, the energy absorbing sections 52 of the EA section 50 are arranged in three rows of four along the vehicle up-down direction and vehicle width direction, the low rigidity sections 54 are made up of two rows of four, and the high rigidity sections 56 are made up of one row of four. The low rigidity sections 54 are provided on the outer side of the fastening section 32 in the vehicle width direction, and the high rigidity sections 56 are provided on the inner side in the vehicle width direction. The lower wall section 56A of the high rigidity section 56 is fastened together with the lower wall section 16A of the rocker 16 to the bottom wall 26 of the battery case 22.

[0052] That is, in the modified example, the upper side of the EA section 50 overlaps with the interior of the passenger compartment 14 in a side view of the vehicle, and the lower side of the EA section 50 overlaps with substantially the entire area of ​​the battery pack 20 in the vertical direction of the vehicle in a side view of the vehicle. In the modified example, the lower wall portion 56A of the high rigidity section 56 is fastened to the lower wall portion 16A of the rocker 16. Therefore, when the rocker 16 and the EA section 50 deform during a side collision of the vehicle 12, movement of the EA section 50 upward of the rocker 16 is suppressed, and it is possible to maintain a state in which the EA section 50 overlaps with the battery pack 20 in a side view of the vehicle.

[0053] Furthermore, in the modified example, the lower wall portion 56A of the high rigidity portion 56 is fastened together with the lower wall portion 16A of the rocker 16 to the bottom wall 26 of the battery case 22. Therefore, in the modified example, an impact load input to the high rigidity portion 56 can be transmitted to the rocker side on the opposite side via the lower wall portion 56A of the high rigidity portion 56 and the bottom wall 26 of the battery case 22, making it possible to distribute the impact load.

[0054] <Additional Notes> The vehicle underbody structure according to the present invention may be formed by appropriately combining the following configurations.

[0055] (Configuration 1) The vehicle comprises a rocker extending in the longitudinal direction of the vehicle on the outer side in the vehicle width direction, an impact absorbing section constituted by a plurality of energy absorbing sections arranged along the vehicle width direction within the rocker, and a battery arranged under the vehicle, and the impact absorbing section has lower rigidity on the outer side in the vehicle width direction than on the inner side in the vehicle width direction at the fastening section where the battery is fastened to the rocker.

[0056] (Configuration 2) The impact absorbing portion includes an outer impact absorbing portion provided on the outer side in the vehicle width direction and an inner impact absorbing portion provided on the inner side in the vehicle width direction.

[0057] (Configuration 3) The outer impact absorbing portion and the inner impact absorbing portion are integrally formed.

[0058] (Configuration 4) The shock absorbing portion is made up of a plurality of members having different rigidities, which are joined together to form an integrated unit.

[0059] (Configuration 5) The fastening portion is provided on the lower wall of the rocker.

[0060] In addition, the present invention can be implemented with various modifications within the scope of the gist thereof. Furthermore, it goes without saying that the scope of the rights of the present invention is not limited to the above-described embodiment. [Explanation of symbols]

[0061] 10 Vehicle undercarriage 12 vehicles 14 Cabin 16 Rocca 16A Lower wall part 20 Battery pack (battery) 32 Fastening part 42 EA section (shock absorbing section) 44 Energy absorption section 46 Low rigidity section (outer impact absorbing section) 48 High rigidity section (inner impact absorbing section) 50 EA section (shock absorbing section) 52 Energy absorption section 54 Low rigidity section (outer impact absorbing section) 56 High rigidity section (inner impact absorbing section)

Claims

1. a rocker extending in the front-rear direction of the vehicle on the outer side of the vehicle width direction of the passenger compartment; an impact absorbing portion configured by a plurality of energy absorbing portions arranged along the vehicle width direction within the rocker; A battery disposed under the vehicle; Equipped with A vehicle undercarriage structure in which the portion of the impact absorbing portion located outside the vehicle width direction of the fastening portion where the battery is fastened to the rocker has lower rigidity than the portion located inside the vehicle width direction of the fastening portion.

2. 2. The vehicle undercarriage structure according to claim 1, wherein the impact absorbing portion includes an outer impact absorbing portion provided on the outer side of the vehicle width direction within the rocker, and an inner impact absorbing portion provided on the inner side of the outer impact absorbing portion in the vehicle width direction.

3. 3. The vehicle underbody structure according to claim 2, wherein the outer impact absorbing portion and the inner impact absorbing portion are integrally formed.

4. 2. The vehicle underbody structure according to claim 1, wherein the impact absorbing portion is made up of a plurality of members having different rigidities, which are joined together to form an integrated structure.

5. The vehicle underbody structure according to claim 1, wherein the fastening portion is provided on a lower wall portion of the rocker.

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