Vehicle under structure

Abstract

The invention provides a vehicle lower structure. The vehicle lower structure includes: a rocker extending in a vehicle front-rear direction on an outer side of a vehicle cabin in a vehicle width direction; an impact absorbing part configured from a plurality of energy absorbing parts arranged side by side in the vehicle width direction within the rocker; and a battery disposed at a lower portion of the vehicle, in the impact absorbing portion, a portion located on an outer side in a vehicle width direction with respect to a coupling portion to which the battery is coupled with respect to the rocker is less rigid than a portion located on an inner side in the vehicle width direction with respect to the coupling portion.

Description

TECHNICAL FIELD

[0001] The present application relates to a vehicle lower structure. BACKGROUND

[0002] In Japanese Patent Application Publication No. 2013-133046, a technology related to a vehicle lower structure in which a battery module is mounted is disclosed. In the prior art, a battery side frame is coupled to a lower side of a lower rail, and the battery side frame is provided at an outer side in a vehicle width direction of the battery module. SUMMARY

[0003] In the prior art described above, in a side collision of the vehicle (hereinafter, referred to as "vehicle side collision"), a side collision load (impact load) input to the lower rail can be input to the battery via the battery side frame.

[0004] The present application takes the above fact into consideration, and aims to obtain a vehicle lower structure that can reduce an impact load input to a battery at the time of a side collision of a vehicle.

[0005] The vehicle lower structure according to the invention described in Technical Solution 1 includes a lower rail that extends in a vehicle front-rear direction at an outer side in a vehicle width direction of a passenger compartment; an impact absorbing portion that is composed of a plurality of energy absorbing portions arranged in the lower rail in the vehicle width direction; and a battery that is disposed at a lower portion of the vehicle, and in the impact absorbing portion, a portion located at an outer side in the vehicle width direction with respect to a coupling portion at which the battery is coupled to the lower rail is lower in rigidity than a portion located at an inner side in the vehicle width direction with respect to the coupling portion.

[0006] In the vehicle lower structure according to the invention described in Technical Solution 1, a lower rail, an impact absorbing portion, and a battery are provided. The lower rail extends in a vehicle front-rear direction at an outer side in a vehicle width direction of a passenger compartment, and the impact absorbing portion is composed of a plurality of energy absorbing portions arranged in the lower rail in the vehicle width direction. In addition, the battery is disposed at a lower portion of the vehicle.

[0007] Here, in the present application, a portion of the impact absorbing portion located at an outer side in the vehicle width direction with respect to a coupling portion at which the battery is coupled to the lower rail is lower in rigidity than a portion located at an inner side in the vehicle width direction with respect to the coupling portion. Thus, in the present application, at the time of a side collision of the vehicle, the amount of absorption of impact energy can be increased at the outer side in the vehicle width direction in the impact absorbing portion, and in addition, deformation can be suppressed at the inner side in the vehicle width direction in the impact absorbing portion.

[0008] Generally, the joint portion in which the battery is incorporated with respect to the lower side beam is provided to be high in rigidity. Therefore, at the time of side collision of the vehicle, by the joint portion, it is possible to obtain sufficient reaction force against plastic deformation of the lower side beam and the impact absorbing portion, and further, in the impact absorbing portion, it becomes easy to crush at the outside in the vehicle width direction compared with the joint portion. Therefore, at the outside in the vehicle width direction in the impact absorbing portion, it is possible to more effectively absorb impact energy.

[0009] The vehicle lower structure according to the invention described in technical solution 2 is the vehicle lower structure according to the invention described in technical solution 1, wherein the impact absorbing portion is configured to include an outside impact absorbing portion provided at the outside in the vehicle width direction within the lower side beam and an inside impact absorbing portion provided at the inside in the vehicle width direction compared with the outside impact absorbing portion.

[0010] In the vehicle lower structure according to the invention described in technical solution 2, the impact absorbing portion is configured to include an outside impact absorbing portion and an inside impact absorbing portion. The outside impact absorbing portion is provided at the outside in the vehicle width direction within the lower side beam, and the inside impact absorbing portion is provided at the inside in the vehicle width direction compared with the outside impact absorbing portion.

[0011] The outside impact absorbing portion is lower in rigidity compared with the inside impact absorbing portion, and thus at the time of side collision of the vehicle, it is possible to increase the amount of absorption of impact energy compared with the inside impact absorbing portion. On the other hand, the inside impact absorbing portion is higher in rigidity compared with the outside impact absorbing portion, and thus at the time of side collision of the vehicle, it is possible to suppress deformation, and thus it is possible to protect the inside of the vehicle cabin and the battery disposed at the inside of the pair of left and right lower side beams.

[0012] The vehicle lower structure according to the invention described in technical solution 3 is the vehicle lower structure according to the invention described in technical solution 2, wherein the outside impact absorbing portion and the inside impact absorbing portion are integrally formed.

[0013] In the vehicle lower structure according to the invention described in technical solution 3, the outside impact absorbing portion and the inside impact absorbing portion are integrally formed. Here, a case where the outside impact absorbing portion and the inside impact absorbing portion are integrally molded is also included, and in this case, it is possible to reduce the number of components.

[0014] The vehicle lower structure according to the invention described in technical solution 4 is the vehicle lower structure according to the invention described in technical solution 1, wherein the impact absorbing portion is configured by a plurality of components different in rigidity, and is integrated by being incorporated with each other.

[0015] In the vehicle lower structure according to the invention described in Technical Solution 4, by making the impact absorbing portion composed of a plurality of members having different rigidity and being integrated by being joined to each other, the degree of freedom in design can be improved. As the "joining", fitting, welding, and brazing can be given.

[0016] The vehicle lower structure according to the invention described in Technical Solution 5 is the vehicle lower structure according to the invention described in Technical Solution 1, in which the joining portion is provided on the lower wall portion of the lower side frame.

[0017] In the vehicle lower structure according to the invention described in Technical Solution 5, by providing the joining portion at the lower wall portion of the lower side frame, the occurrence of stress concentration generated for the battery pack via the joining portion at the time of side collision of the vehicle can be suppressed compared to the case where the joining portion is provided at the side wall portion of the lower side frame.

[0018] As described above, in the vehicle lower structure according to the invention, the impact load input to the battery at the time of side collision of the vehicle can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0019] Features, advantages, and technical and industrial significance of exemplary embodiments of the present application will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

[0020] Figure 1 is a main part enlarged cross-sectional view of a main part after enlargement in a vehicle to which the vehicle lower structure according to the first embodiment is applied.

[0021] Figure 2 is a main part enlarged cross-sectional view of a main part after enlargement in a vehicle to which the vehicle lower structure according to the first embodiment is applied, showing Modification 1. DETAILED DESCRIPTION

[0022] A vehicle lower structure according to an embodiment of the present application will be described with reference to the drawings. In each drawing, arrow marks UP and RH respectively denote an upward direction and a rightward direction of a vehicle to which the vehicle lower structure according to the present embodiment is applied. Hereinafter, in the case where the directions are not particularly described and only front and rear, left and right, and upper and lower directions are used, the front and rear directions denote a vehicle front and rear direction, the left and right directions denote a vehicle left and right direction (a vehicle width direction), and the upper and lower directions denote a vehicle upper and lower direction. In each drawing, a part of a member or a part of a symbol can be omitted from the viewpoint of easy observation of the drawing.

[0023] Configuration of the vehicle lower structure

[0024] First, the configuration of the vehicle lower structure according to the embodiment of the present application will be described.

[0025] As shown in Figure 1 the vehicle (vehicle body) 12 to which the vehicle lower structure 10 according to the embodiment of the present application is applied is provided with a pair of left and right lower side members 16 that respectively constitute a vehicle frame and extend in the vehicle front-rear direction at both ends of the lower portion of a vehicle cabin 14 in the vehicle width direction. Although not shown, a front cross member (omitted from illustration) is provided at the front ends of the pair of left and right lower side members 16 in the vehicle width direction, and a rear cross member (omitted from illustration) is provided at the rear ends of the pair of left and right lower side members 16 in the vehicle width direction.

[0026] Further, the vehicle 12 according to the embodiment is a battery electric vehicle (BEV) that travels using the driving force of an electric motor, which is not shown. A battery pack (battery) 20 that houses a plurality of single cells 18 that supply electric power for driving the electric motor is provided at the lower portion of the vehicle 12. In addition, the vehicle 12 can also be a plug-in hybrid electric vehicle (PHEV) or a fuel cell electric vehicle (FCEV), or the like.

[0027] The battery pack 20 is, for example, made of a light metal such as an aluminum alloy, and is configured in a manner that includes a battery case 22 that is rectangular in shape in plan view with the vehicle front-rear direction as the length direction and has an open upper side. In addition, the battery case 22 can use a resin member such as carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP) in addition to a metal.

[0028] Further, the battery case 22 is, for example, closed by a cover 24 that is rectangular in plan view in a state in which the plurality of single cells 18 are housed. The cover 24 is, for example, made of a light metal such as an aluminum alloy, and is in the form of a plate with the vehicle up-down direction as the plate thickness direction, and is integrated with the battery case 22 by welding or the like. The cover 24 constitutes a floor that constitutes a floor portion in the vehicle cabin 14, although not shown, a floor cross member is disposed above the cover 24 in a manner that is erected between the pair of left and right lower side members 16 in the vehicle width direction.

[0029] On the other hand, the battery case 22 is configured, for example, in a manner including a bottom wall 26 and a side wall 28 provided upright from an outer edge of the bottom wall 26. The bottom wall 26 extends to the outside in the vehicle width direction beyond the side wall 28, and is coupled to the lower wall portion 16A of the lower side member 16 via a coupling portion 32 such as a bolt 30. Thus, the battery case 22 is supported with respect to the lower side member 16.

[0030] Further, in the present embodiment, the lower side member 16 is configured in a manner including an outer portion 36 and an inner portion 38, and a closed cross section portion 40 is formed using the outer portion 36 and the inner portion 38. Also, an EA portion (impact absorbing portion) 42 is provided (disposed) within the closed cross section portion 40.

[0031] The closed cross section portion 40 is formed, for example, in a manner in which a cross section shape when cut along the vehicle width direction and the vehicle up-down direction is a substantially hexagonal shape, and a dimension in the vehicle up-down direction is longer than a dimension in the vehicle width direction. Also, the cross section shape of the closed cross section portion 40 is not particularly limited.

[0032] Further, although the lower side member 16 is illustrated in a state in which the outer portion 36 and the inner portion 38 are integrally molded out in Figure 1 , the outer portion 36 and the inner portion 38 can of course be formed by different members and be integrated by being joined to each other. Also, the EA portion 42 can be coupled to the lower side member 16 via a coupling portion such as a bolt, which is not illustrated, or can be integrally molded with the lower side member 16 by extrusion molding or the like.

[0033] In the present embodiment, the EA portion 42 is configured by a plurality of energy absorbing portions 44, and a cross section shape when cut along the vehicle width direction and the vehicle up-down direction of the energy absorbing portions 44 is set to a closed cross section shape in a substantially rectangular shape. Further, in the present embodiment, a substantially central portion in the vehicle up-down direction of the EA portion 42 is at substantially the same height as a position of the cover 24.

[0034] That is, an upper portion side of the EA portion 42 overlaps the inside of the passenger compartment 14 when viewed in the vehicle side view, and a lower portion side of the EA portion 42 overlaps an upper portion of the battery pack 20 when viewed in the vehicle side view. Also, in a case in which a floor cross member is provided within the passenger compartment 14, the upper portion side of the EA portion 42 overlaps the floor cross member when viewed in the vehicle side view.

[0035] In this embodiment, the EA portion 42 is formed of a metal such as iron or aluminum alloy, or carbon fiber reinforced plastic (CRFP). The EA portion 42 is configured to include a low-rigidity portion (outer impact absorbing portion) 46 disposed on the outer side in the vehicle width direction, and a high-rigidity portion (inner impact absorbing portion) 48 disposed on the inner side in the vehicle width direction. For ease of illustration, the low-rigidity portion 46 is hatched, and the high-rigidity portion 48 is cross-hatched.

[0036] In this embodiment, for example, the low-rigidity portion 46 is formed to be thinner than the high-rigidity portion 48 and has lower rigidity than the high-rigidity portion 48. The "low-rigidity portion" herein is a component referred to for convenience in comparison with the "high-rigidity portion" and ensures the rigidity that is the original function of the EA portion 42.

[0037] The low-rigidity portion 46 and the high-rigidity portion 48 may be integrally molded or formed separately. If the low-rigidity portion 46 and the high-rigidity portion 48 are formed separately, they may be integrated (integrally formed) by welding, deposition, bonding, fitting, or the like, depending on the material.

[0038] Furthermore, in this embodiment, the low-rigidity portions 46 are arranged in two rows of three, and the high-rigidity portions 48 are arranged in one row of three. Furthermore, the coupling portion 32 is provided below the high-rigidity portions 48. Specifically, in this embodiment, the low-rigidity portions 46 are provided on the outer side of the coupling portion 32 in the vehicle width direction, and the high-rigidity portions 48 are provided on the inner side of the coupling portion 32 in the vehicle width direction.

[0039] The role and effect of vehicle substructure

[0040] Next, the functions and effects of the vehicle understructure according to the present embodiment will be described.

[0041] like Figure 1 As shown, in this embodiment, the vehicle lower structure 10 includes a rocker 16, an energy absorbing portion 42, and a battery pack 20. The rocker 16 extends in the vehicle longitudinal direction outboard of the vehicle cabin 14 in the vehicle width direction. The energy absorbing portion 42 is composed of a plurality of energy absorbing portions 44 arranged in a row along the vehicle width direction within the rocker 16. Furthermore, the battery pack 20 is disposed in the lower portion of the vehicle.

[0042] Here, in the present embodiment, in the EA portion 42, the portion located on the outer side in the vehicle width direction compared with the joint portion 32 at which the battery pack 20 is joined to the lower side frame 16 is lower in rigidity than the portion located on the inner side in the vehicle width direction compared with the joint portion 32. Thus, in the present embodiment, at the time of a side collision of the vehicle 12, the amount of absorption of impact energy can be increased at the outer side in the vehicle width direction in the EA portion 42, and in addition, deformation can be suppressed at the inner side in the vehicle width direction in the EA portion 42.

[0043] Generally, since the joint portion 32 of the battery pack 20 is provided with high rigidity, at the time of a side collision of the vehicle 12, by the joint portion 32, a sufficient reaction force can be obtained against plastic deformation of the lower side frame 16 and the EA portion 42. Thus, at the time of a side collision of the vehicle 12, the EA portion 42 is easily crushed at the outer side in the vehicle width direction compared with the joint portion 32, and thus impact energy can be more effectively absorbed. As a result, in the present embodiment, impact load input to the battery pack 20 can be reduced at the time of a side collision of the vehicle 12.

[0044] The structure of the EA portion 42 in the present embodiment will be described in detail. The EA portion 42 is composed of a plurality of energy absorbing portions 44 that are provided in a substantially rectangular shape and in a closed cross-sectional shape. The EA portion 42 changes the plate thickness in the energy absorbing portions 44. The EA portion 42 is composed of a low rigidity portion 46 and a high rigidity portion 48. Further, the low rigidity portion 46 in which the plate thickness is relatively thin is provided at the outer side in the vehicle width direction, and the high rigidity portion 48 in which the plate thickness is relatively thick is provided at the inner side in the vehicle width direction.

[0045] Since the low rigidity portion 46 is lower in rigidity than the high rigidity portion 48, the amount of absorption of impact energy can be increased compared with the high rigidity portion 48. On the other hand, since the high rigidity portion 48 is higher in rigidity than the low rigidity portion 46, in the present embodiment, deformation can be suppressed at the time of a side collision of the vehicle 12, and thus the passenger compartment 14 and the battery pack 20 can be protected.

[0046] In the present embodiment, since the rigidity is changed by changing the plate thickness by the low rigidity portion 46 and the high rigidity portion 48, the low rigidity portion 46 and the high rigidity portion 48 can be integrally formed. Thus, by integrally forming the low rigidity portion 46 and the high rigidity portion 48, the number of components can be reduced.

[0047] Further, in the present embodiment, the joint portion 32 is provided on the lower wall portion 16A of the lower side frame 16. Thereby, although not illustrated, compared to a case where the joint portion 32 is provided on the side wall portion of the lower side frame 16, it is possible to reduce the gap between the lower side frame 16 and the battery pack 20. That is, in the present embodiment, it is possible to increase the amount of the battery pack 20 in correspondence with the amount by which the gap can be reduced, and it is possible to increase the battery capacity in correspondence with the amount by which the battery pack 20 is increased.

[0048] Further, as a comparative example, although not illustrated, in a case where the joint portion 32 is provided between the lower side frame 16 and the battery pack 20, there is a possibility that stress concentrates on the battery pack 20 via the joint portion 32 at the time of a side collision of the vehicle 12. On the other hand, since the battery pack 20 is housed between the left and right lower side frames 16 in the present embodiment, it is possible to suppress the occurrence of stress concentration on the battery pack via the joint portion 32 at the time of a side collision of the vehicle 12. That is, in the present embodiment, it is possible to protect the battery pack 20 at the time of a side collision of the vehicle 12.

[0049] Further, in the present embodiment, the substantially central portion of the EA portion 42 in the vehicle up-down direction becomes substantially the same height as the position of the cover 24. That is, the upper portion side of the EA portion 42 overlaps the inside of the passenger compartment 14 when viewed from above, and the lower portion side of the EA portion 42 overlaps the battery pack 20 when viewed from the side of the vehicle. Therefore, in the present embodiment, it is possible to protect the inside of the passenger compartment 14 and the battery pack 20 at the time of a side collision of the vehicle 12.

[0050] However, although in the present embodiment, the rigidity is changed by changing the plate thickness in the EA portion 42 to utilize the low rigidity portion 46 and the high rigidity portion 48, since the rigidity of the low rigidity portion 46 only needs to be lower than the high rigidity portion 48, it is not limited thereto. Therefore, it is not necessary to integrally form the low rigidity portion 46 and the high rigidity portion 48. That is, the low rigidity portion 46 and the high rigidity portion 48 can also be formed separately.

[0051] For example, in a case where the low rigidity portion 46 and the high rigidity portion 48 are formed separately by different materials, the low rigidity portion 46 and the high rigidity portion 48 are integrated by being joined by welding, deposition, bonding, fitting, or the like in correspondence with the materials. In this way, by forming the low rigidity portion 46 and the high rigidity portion 48 separately, it is possible to improve the degree of freedom of design compared to a case where they are integrally formed.

[0052] Furthermore, in order to improve the rigidity of the high-rigidity portion 48 compared to the low-rigidity portion 46, a reinforcement portion or member such as a diagonal strut 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 also be a triangular or hexagonal shape.

[0053] Modifications of this embodiment

[0054] In the above embodiments, Figure 1 As shown, the energy absorbing portions 44 of the EA portion 42 are arranged in three rows x three along the vehicle vertical direction and the vehicle width direction. The upper side of the EA portion 42 overlaps with the interior of the vehicle cabin 14 when viewed from the side of the vehicle, and the lower side of the EA portion 42 overlaps with the upper portion of the battery pack 20 when viewed from the side of the vehicle. However, the arrangement of the EA portion 42 is not limited to this.

[0055] For example, in the modified example, Figure 2 As shown, the energy absorbing portions 52 of the EA section 50 are arranged in three rows of four along the vehicle vertical and width directions. The low-rigidity portions 54 are arranged in two rows of four, and the high-rigidity portions 56 are arranged in one row of four. Furthermore, the low-rigidity portions 54 are positioned outboard of the joint 32 in the vehicle width direction, while the high-rigidity portions 56 are positioned inboard in the vehicle width direction. Furthermore, the lower wall portion 56A of the high-rigidity portion 56 is joined to the bottom wall 26 of the battery case 22, along with the lower wall portion 16A of the rocker 16.

[0056] Specifically, in this modification, the upper side of the EA portion 50 overlaps the interior of the vehicle cabin 14 when viewed from the side of the vehicle, and the lower side of the EA portion 50 overlaps substantially the entire vertical region of the battery pack 20 when viewed from the side of the vehicle. In this modification, the lower wall portion 56A of the high-rigidity portion 56 is joined to the lower wall portion 16A of the rocker 16. Therefore, during a side collision of the vehicle 12, even when the rocker 16 and the EA portion 50 deform, movement of the EA portion 50 upward relative to the rocker 16 is suppressed, while maintaining the EA portion 50's overlap with the battery pack 20 when viewed from the side of the vehicle.

[0057] Furthermore, in the modified example, the lower wall portion 56A of the high-rigidity portion 56 and the lower wall portion 16A of the rocker 16 are jointly joined 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, thereby achieving load distribution of the impact load.

[0058] Notes

[0059] In addition, the following structure can be appropriately combined and provided as the vehicle lower structure according to the present application.

[0060] Structure 1

[0061] A vehicle lower structure includes a lower side frame extending in a vehicle longitudinal direction at an outer side in a vehicle width direction of a passenger compartment; an impact absorbing portion configured by a plurality of energy absorbing portions arranged in the vehicle width direction in the lower side frame; and a storage battery arranged at a lower portion of the vehicle, the impact absorbing portion being less rigid at an outer side in the vehicle width direction than at an inner side in the vehicle width direction.

[0062] Structure 2

[0063] The impact absorbing portion is configured to include an outer side impact absorbing portion arranged at an outer side in the vehicle width direction and an inner side impact absorbing portion arranged at an inner side in the vehicle width direction.

[0064] Structure 3

[0065] The outer side impact absorbing portion and the inner side impact absorbing portion are integrally formed.

[0066] Structure 4

[0067] The impact absorbing portion is configured by a plurality of members having different rigidity and is integrated by bonding.

[0068] Structure 5

[0069] The bonding portion is arranged on a lower wall portion of the lower side frame.

[0070] In addition, the present application can be variously changed and implemented without departing from the gist thereof. Furthermore, the scope of the right of the present application is of course not limited to the above-described embodiments.

Claims

1. A vehicle lower structure comprising: a rocker extending in the vehicle front-rear direction at an outer side of the vehicle compartment in the vehicle width direction; an impact absorbing portion composed of a plurality of energy absorbing portions arranged in a row along the vehicle width direction within the rocker; A battery is arranged at the lower part of the vehicle, The impact absorbing portion has a portion located outside the vehicle width direction relative to a connection portion where the battery is connected to the rocker, and has lower rigidity than a portion located inside the vehicle width direction relative to the connection portion.

2. The vehicle lower structure according to claim 1, wherein: The impact absorbing portion is configured to include 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 relative to the outer impact absorbing portion.

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

4. The vehicle lower structure according to claim 1, wherein: The shock absorbing portion is composed of a plurality of members having different rigidities, and is integrated by being coupled to each other.

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

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