Vehicle battery unit

Abstract

To provide a battery unit of a vehicle capable of efficiently receiving an input impact load by a part other than a battery cell while avoiding increase in size and weight of a battery storage case.SOLUTION: The battery unit includes a battery module and a battery housing case. The battery housing case includes a pair of frame members and a plurality of cross members. Both end portions of the cross member in the extension direction are connected to the pair of frame members. The module case is provided with cover walls respectively connected to two adjacent cross members. At least one of the cross members has a multiple rib structure and a single rib portion. In the multiple rib structure portion, the ribs are branched into a plurality of ribs from one end side toward the other end side and then merged into one rib again. An end portion of the single rib portion in the extending direction is connected to the multiple rib structure portion. The end edge of the cover wall is connected to the vicinity of a portion where the number of ribs of the multiple rib structure changes from a plurality to one.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a battery unit for a vehicle in which a battery module is housed in a battery housing case.

Background Art

[0002] As a battery unit for a vehicle, there is known one in which a plurality of battery cells are housed in a battery housing case, and the battery housing case is attached to a skeletal member of the vehicle (see, for example, Patent Document 1).

[0003] The battery unit for a vehicle described in Patent Document 1 includes a battery module in which a plurality of stacked battery cells are stored inside, and a battery housing case that houses the battery module. The battery housing case includes a bottom wall member on which the battery module is placed on the upper surface, and a plurality of frame members connected to the upper surface of the bottom wall member and surrounding the outside of the battery module.

[0004] In the battery unit for a vehicle described in Patent Document 1, since a plurality of frame members are connected to the bottom wall member so as to surround the outside of the battery module, when an impact load is input from the outside, the battery module (battery cells) on the bottom wall member can be protected by the frame members.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The vehicle battery unit described in Patent Document 1 is structured so that when an impact load is applied from the outside, the load is absorbed by the frame members of the battery housing case. Therefore, in order to reliably protect the battery cells housed in the battery housing case from the input of an impact load, it is necessary to increase the number of frame members or to enlarge the frame members. However, this results in a larger and heavier battery housing case, so improvement is desired.

[0007] Therefore, the present invention aims to provide a vehicle battery unit that can efficiently absorb incoming impact loads in parts other than the battery cells, while avoiding an increase in the size and weight of the battery housing case. Furthermore, the present invention contributes to the energy efficiency of the vehicle by making the battery housing case smaller and lighter. [Means for solving the problem]

[0008] To solve the above problems, the vehicle battery unit according to the present invention employs the following configuration. That is, the vehicle battery unit according to the present invention comprises a battery module (e.g., battery module 7 in the embodiment) in which a battery cell (e.g., battery cell 6 in the embodiment) is housed in a module case (e.g., module case 40 in the embodiment), and a battery housing case (e.g., battery housing case 10 in the embodiment) attached to a vehicle frame member (e.g., side sill 3 in the embodiment) and housing the battery module inside, wherein the battery housing case comprises a pair of frame members (e.g., frame member 11 in the embodiment) extending along a first direction substantially perpendicular to the vertical direction, and a plurality of cross members (e.g., first cross member 12f, second cross member in the embodiment) extending along a second direction substantially perpendicular to the vertical direction and the first direction, with both ends in the extending direction connected to the pair of frame members. The module case comprises a member 12s and a third cross member 12t), and the module case includes a cover wall (for example, a cover wall 42 in the embodiment) that covers the top of the battery cell and whose edges on both sides in the first direction are connected to two adjacent cross members, respectively, and at least one of the adjacent cross members has a multi-rib structure (for example, a multi-rib structure 51 in the embodiment) in which ribs (for example, ribs 50 in the embodiment) branch from one to multiple and then merge back into one from one end to the other in the second direction, and a single rib section (for example, a single rib section 52 in the embodiment) that extends along the second direction and whose end in the extending direction is connected to the multi-rib structure, and the edge of the cover wall is connected near the location in which the number of ribs in the multi-rib structure changes from multiple to one.

[0009] In this embodiment of the battery unit, the edges of the battery module's cover wall in the first direction are connected to two adjacent cross members. Therefore, when an impact load is applied to one of the frame members from one side in the second direction, the impact load transmitted to the adjacent cross member is efficiently transmitted to the other cross member through the cover wall. As a result, the applied impact load is efficiently distributed and supported by multiple cross members through the cover wall. In particular, in this embodiment, at least one of adjacent cross members has a multi-rib structure and a single rib section interconnected in a second direction, and the edge of the cover wall is connected near the point where the number of ribs in the multi-rib structure changes from multiple to one. Therefore, the impact load transmitted to the multi-rib structure of the cross member is transmitted to the cover wall through a section that is relatively prone to outward movement in response to the input load. As a result, the impact load applied to one cross member is efficiently transmitted to the other cross member through the cover wall. Therefore, by adopting this configuration, it becomes possible to efficiently absorb the input impact load using the cover wall without increasing the number of cross members or making the cross members larger.

[0010] The cross member having the multi-rib structure and the single rib portion may also be provided with a widened portion (for example, the widened portion 45 in the embodiment) whose width in the first direction gradually increases in a widening manner toward the fixing portion with the skeletal member (for example, the fixing portion 44 in the embodiment).

[0011] In this case, an impact load applied to one of the frame members from one side in the second direction is transmitted from the fixing point of the cross member to the frame member through the widened section to the multi-rib structure and the single rib section. Since the width of the widened section gradually decreases in the first direction from the fixing point to the frame member toward the multi-rib structure and the single rib section, the load applied from the frame member to the cross member is more easily transmitted to the multi-rib structure and the single rib section. For this reason, an impact load applied to one cross member is more easily transmitted to the other cross member via the cover wall. Furthermore, an impact load input from one side of one cross member is transmitted to the other frame member through the widened portion on the other side of that cross member. At this time, since the width of the widened portion on the other side gradually increases in the first direction toward the fixing portion with the other frame member, the impact load is stably absorbed by a wide area in the first direction of the other frame member. Therefore, by adopting this configuration, it becomes possible to more efficiently absorb the input shock load in parts other than the battery cell.

[0012] Near the point in the cross member where the number of ribs in the multi-rib structure changes from multiple to one, a connecting portion to the cover wall (for example, a fastening boss portion 54 in the embodiment) may be provided via a plurality of reinforcing ribs (for example, reinforcing rib 53 in the embodiment) extending along the first direction.

[0013] In this case, multiple reinforcing ribs extend from the multi-rib structure of the cross member in a direction perpendicular to the extension direction of the cross member, and connection parts to the cover wall are connected to these multiple reinforcing ribs. Therefore, it becomes possible to efficiently transmit the impact load applied to the multi-rib structure of the cross member to the cover wall through the multiple reinforcing ribs.

[0014] A separation space (for example, separation space S in the embodiment) that separates the skeletal member and the battery module in the second direction may be provided between them.

[0015] In this case, when an impact load is applied to one of the frame members from one side in the second direction, that impact load is absorbed by the cross member and the cover wall of the battery module. Even if a part of one of the frame members is displaced in the second direction, a separation space is maintained between the frame member and the battery module, making it difficult for the load to be directly transmitted from the frame member to the battery module. Therefore, by adopting this configuration, it becomes possible to protect the battery cells more advantageously when an impact load is applied.

[0016] The two adjacent cross members may be provided with their connecting portions to the cover wall (for example, fastening boss portions 54, 65 in the embodiment) at positions offset from each other in the second direction.

[0017] In this case, when an impact load is input from one side in the second direction to one of the skeletal members, the load is received by two adjacent cross members and also by the cover wall. At this time, the connecting portions, where the load is transmitted from the two cross members to the cover wall, are arranged at positions shifted from each other in the second direction. Therefore, when the impact load is input, it becomes difficult for the cover wall to bend and deform, and it becomes possible to efficiently receive the impact load by the cover wall.

Advantages of the Invention

[0018] According to the battery unit of the vehicle according to the present invention, while avoiding an increase in the size and weight of the battery housing case, it is possible to efficiently receive the input impact load by a portion other than the battery cells. Therefore, when the battery unit according to the present invention is adopted, it is possible to contribute to the improvement of the energy efficiency of the vehicle by reducing the size and weight of the entire battery housing case.

Brief Description of the Drawings

[0019] [Figure 1] Cross-sectional view showing the structure of the lower part of the vehicle body of the vehicle according to the embodiment. [Figure 2] Plan view of the battery unit according to the embodiment. [Figure 3] Plan view of the battery unit showing a partially enlarged view of FIG. 2. [Figure 4] Enlarged view of part IV of FIG. 3. [Figure 5] Plan view of a portion corresponding to part V of FIG. 3 of the third cross member according to the embodiment.

Mode for Carrying Out the Invention

[0020] Hereinafter, an embodiment of the present invention will be described based on the drawings. In appropriate places in the drawings, an arrow FR indicating the front of the vehicle 1, an arrow UP indicating the upper side of the vehicle 1, and an arrow LH indicating the left side of the vehicle 1 are marked.

[0021] Figure 1 shows the underbody structure of vehicle 1. Figure 1 is a cross-sectional view of the underside of vehicle 1, cut in a direction perpendicular to the longitudinal direction of the vehicle body. A pair of side sills 3, which are structural members of the vehicle body, are positioned at the lower part of both sides in the vehicle width direction of the passenger compartment 2, extending substantially along the longitudinal direction of the vehicle body. In Figure 1, only one side sill 3 is shown. Floor panels 4 are installed on the left and right side sills 3. Below the floor panels 4, a battery unit 5 is positioned substantially along the underside of the floor panels 4. The battery unit 5 comprises a battery module 7 that houses multiple stacked battery cells 6 (see Figure 2), and a battery housing case 10 that is attached to the left and right side sills 3 of the vehicle and houses multiple battery modules 7 inside.

[0022] The battery housing case 10 comprises a case body 25 on which multiple battery modules 7 (battery cells 6) and control equipment (not shown) are mounted on the upper side, and a cover member 30 that covers the top of the case body 25. The case body 25 is formed in a substantially rectangular shape when viewed from above. The left and right side edges of the case body 25 are fixed to the lower surfaces of the corresponding left and right side sills 3 by fastening members (not shown).

[0023] The side sill 3 is constructed by sandwiching a stiffener 3C between a hat-shaped side sill inner 3A and a side sill outer 3B. The side sill inner 3A and the side sill outer 3B have joining flanges 3Af and 3Bf above and below each other. The upper and lower joining flanges 3Af and 3Bf of the side sill inner 3A and the side sill outer 3B are positioned opposite each other. The opposing joining flanges 3Af and 3Bf are connected by welding or the like with the stiffener 3C sandwiched between them. The side sill inner 3A has an inner bulge portion 3Ac with a U-shaped cross-section that bulges inward in the vehicle width direction from the base of the upper and lower joining flanges 3Af and 3Bf. The left and right side edges of the case body 25 are connected to the lower surface of the inner bulge portion 3Ac of the side sill inner 3A.

[0024] Figure 2 is a plan view of the battery unit 5. Note that the cover member 30 is omitted in Figure 2. The battery housing case 10 has a case body 25 which includes a pair of skeletal members 11 that extend substantially along the longitudinal direction of the vehicle body. The pair of skeletal members 11 are spaced apart in the vehicle width direction. The pair of skeletal members 11 are connected by a first cross member 12f, a second cross member 12s, and a third cross member 12t, which extend along the vehicle width direction. The ends of the first cross member 12f in the direction of extension are connected near the front ends of the left and right skeletal members 11, and the ends of the second cross member 12s in the direction of extension are connected near the rear ends of the left and right skeletal members 11. The ends of the third cross member 12t in the direction of extension are connected to the approximate center position in the longitudinal direction of the left and right skeletal members 11.

[0025] In this embodiment, the vehicle body's longitudinal direction is a first direction substantially perpendicular to the vertical direction, and the vehicle width direction is a second direction substantially perpendicular to both the vertical direction and the first direction. The pair of skeletal members 11 extend along the first direction (vehicle body longitudinal direction) and are spaced apart from each other in the second direction (vehicle width direction). The first, second, and third cross members 12f, 12s, and 12t extend along the second direction (vehicle width direction) and constitute cross members whose ends in the extension direction are connected to the pair of skeletal members 11.

[0026] The case body 25 further includes a bottom wall member 13 that covers the space below between a pair of skeletal members 11. The bottom wall member 13 is formed in a rectangular shape in plan view, and the lower ends of the first, second, and third cross members 12f, 12s, and 12t are connected to the pair of skeletal members 11 on its upper side. Multiple (four) battery modules 7 are placed on the upper side of the bottom wall member 13. Two battery modules 7 are placed side by side in the vehicle width direction on the front upper surface of the bottom wall member 13 with the third cross member 12t in between, and the remaining two battery modules 7 are similarly placed side by side in the vehicle width direction on the rear upper surface of the bottom wall member 13 with the third cross member 12t in between. The battery modules 7 (multiple battery cells 6) housed in the case body 25 are surrounded on the outside by the pair of skeletal members 11 and the first, second, and third cross members 12f, 12s, and 12t. Furthermore, the number of battery modules 7 housed in the battery housing case 10 is not limited to four; any number can be selected depending on the size of the battery housing case 10 and the layout of the mounted components.

[0027] Furthermore, as shown in Figure 2, an equipment mounting frame 33 is installed on the upper part of the first cross member 12f and the second cross member 12s of the battery housing case 10. The equipment mounting frame 33 is installed in the center of the vehicle width direction of the first cross member 12f and the second cross member 12s so as to straddle the front and rear of the central area in the vehicle width direction above the four battery modules 7. Control equipment and its wiring, etc. (not shown), are mounted on the upper part of the equipment mounting frame 33.

[0028] The bottom wall member 13 comprises a base wall 8b facing the battery module 7 housing and a flow path forming wall 8f joined to its lower surface. The flow path forming wall 8f forms a coolant passage 14 between itself and the lower surface of the base wall 8b for circulating coolant inside. Multiple battery modules 7 housed in the battery housing case 10 are cooled by the coolant flowing through the coolant passage 14. The bottom wall member 13, with its base wall 8b and the flow path forming wall 8f below it, constitutes a multi-wall structure with a hollow section inside. The bottom wall member 13 maintains high rigidity through this multi-wall structure.

[0029] Each battery module 7 houses multiple battery cells 6 within a rectangular module case 40 with a narrow vertical width. The multiple battery cells 6 are stacked along the vehicle width direction within the module case 40. The battery cells 6 are grouped into battery modules 7 in predetermined numbers and stored in a battery housing case 10. The module case 40 comprises a case body 41 that opens upwards and houses multiple battery cells 6 inside, and a cover wall 42 attached to the upper surface of the case body 41 and closing the opening of the case body 41. When the cover wall 42 is attached to the case body 41, it covers the top of the multiple battery cells 6 inside the case body 41. The case body 41 and cover wall 42 that form the module case 40 are made of a highly rigid metal plate or the like. Furthermore, each battery module 7 housed in the battery housing case 10 is provided with a space S between it and the frame member 11 so that it does not come into contact with the adjacent frame member 11 in the vehicle width direction.

[0030] As shown in Figure 1, the skeletal member 11 has a hollow base frame portion 15 to which the extended ends of the first, second, and third cross members 12f, 12s, and 12t are connected on the inner surface in the vehicle width direction, and a hollow mounting frame portion 16 that extends outward in the vehicle width direction from the outer end of the base frame portion 15 in the vehicle width direction. The base frame section 15 is formed as a closed rectangular section with a vertically elongated cross-section perpendicular to the longitudinal direction of the vehicle body. The rectangular closed section of the base frame section 15 extends substantially along the longitudinal direction of the vehicle body.

[0031] The mounting frame portion 16 has an upper wall portion 17 whose inner end in the vehicle width direction is connected to the base frame portion 15 at approximately the center position in the height direction, and a lower wall portion 18 whose inner end in the vehicle width direction is connected to the lower end of the base frame portion 15. The lower wall portion 18 is positioned at approximately the same height as the bottom wall member 13. The outer ends of the upper wall portion 17 and the lower wall portion 18 in the vehicle width direction are closed by end walls 29 that stand upright approximately along the vertical direction. The mounting frame portion 16 forms a horizontally elongated, roughly rectangular closed cross section by the side walls on the vehicle width direction of the base frame portion 15, the upper wall portion 17, the lower wall portion 18, and the end wall 29. This closed cross section extends in the longitudinal direction of the vehicle body. Furthermore, the closed cross section of the mounting frame portion 16 is reinforced by reinforcing ribs 27 and 28.

[0032] Figure 3 is a plan view of the battery unit 5, shown as an enlarged portion of Figure 2. Figure 4 is an enlarged view of section IV in Figure 3. The third cross member 12t, positioned at the center of the battery housing case 10 in the front-rear direction, comprises a lower member 12tL whose ends on both sides in the extension direction are welded and fixed to the base frame portions 15 of the left and right frame members 11, and an upper member 12tU that is superimposed on the upper surface of the lower member 12tL and fixed to the lower member 12tL in that state by fastening members 35. The upper member 12tU has an extension length in the vehicle width direction that is slightly shorter than that of the lower member 12tL. At both ends of the lower member 12tL in the vehicle width direction, widened portions 45 are formed, in which the width in the front-rear direction gradually increases toward the fixing portion 44 (welded fixing portion) with the frame member 11. Both ends of the upper member 12tU in the vehicle width direction are connected by fastening members 35 to the narrowest part of the widened portion 45 of the lower member 12tL.

[0033] As shown in Figure 3, the upper surface of the upper member 12tU is provided with a multi-rib structure 51 in which a rib 50 branches into two (multiple) from one end in the vehicle width direction (second direction) toward the other end, and then rejoins into one, and a single rib section 52 that extends along the vehicle width direction (second direction), with the end in the extending direction connected to the vehicle width direction end (the single rib 50) of the multi-rib structure 51. The multi-rib structure 51 and the single rib section 52 are arranged alternately along the vehicle width direction on the upper surface of the upper member 12tU (third cross member 12t). A multi-rib structure 51 is located at both ends of the upper member 12tU (third cross member 12t) in the vehicle width direction. The two ribs 50 that branch into two in each multi-rib structure 51 extend along the vehicle width direction so as to be parallel to each other. Furthermore, the multi-rib structure 51 at both ends in the vehicle width direction is connected to the widened section 45 on the lower member 12tL side at the point where two ribs 50 merge into one.

[0034] Figure 5 is an enlarged plan view of the portion of the third cross member 12t corresponding to section V in Figure 3. In each multi-rib structure 51 of the upper member 12tU, near the point where the number of ribs 50 changes from two (multiple) to one, a pair of reinforcing ribs 53 extending parallel to the front in the longitudinal direction and a pair of reinforcing ribs 53 extending parallel to the rear in the longitudinal direction are integrally formed. Each pair of reinforcing ribs 53 is spaced a predetermined distance apart in the vehicle width direction. Furthermore, fastening boss portions 54 are provided in series at the ends of each pair of reinforcing ribs 53 in the direction of extension, to which the edge of the cover wall 42 of the battery module 7 is fastened and fixed. Each fastening boss portion 54 has an insertion hole 56 into which the shaft portion of a fastening member 55 (see Figure 3) is inserted.

[0035] On the other hand, as shown in Figure 3, the battery module 7, which is positioned on the rear side of the third cross member 12t, has fastening tongues 60 extending from the front edge of its cover wall 42, which overlap the upper surface of each fastening boss portion 54 on the rear edge of the third cross member 12t. Each fastening tongue 60 on the front edge of the cover wall 42 is fastened and fixed to the corresponding fastening boss portion 54 by a fastening member 55 when it is overlapped with the upper surface of that fastening boss portion 54.

[0036] Similarly, the battery module 7, positioned on the front side of the third cross member 12t, has fastening tongues 60 extending from the rear edge of its cover wall 42, which overlap the upper surface of each fastening boss portion 54 on the front edge of the third cross member 12t. Each of these fastening tongues 60 on the rear edge of the front cover wall 42 overlaps the upper surface of the corresponding fastening boss portion 54 and is fastened and fixed to the fastening boss portion 54 by a fastening member 55.

[0037] Furthermore, as shown in Figure 3, a plurality of fastening bosses 65 are provided projecting forward from the front edge of the rear second cross member 12s. The battery module 7, which is positioned in front of the second cross member 12s, has fastening tongues 67 extending from the rear edge of its cover wall 42, which overlap the upper surface of each fastening boss 65 on the front edge of the second cross member 12s. Each fastening tongue 67 on the rear edge of the rear cover wall 42 is fastened and fixed to the corresponding fastening boss 65 by a fastening member 55 when it is overlapped with the upper surface of that fastening boss 65.

[0038] Here, the fastening boss portion 54 (connecting portion to the cover wall 42) of the central third cross member 12t and the fastening boss portion 65 (connecting portion to the cover wall 42) of the rear second cross member 12s are positioned offset from each other in the vehicle width direction. In other words, the connecting portion between the cover wall 42 and the third cross member 12t on the front edge side and the connecting portion between the cover wall 42 and the second cross member 12s on the rear edge side are all positioned offset from each other in the vehicle width direction.

[0039] Although Figure 3 does not show the connection between the first cross member 12f and the front cover wall 42, the connection between the first cross member 12f and the front cover wall 42 has the same structure as the connection between the second cross member 12s and the rear cover wall 42. The connection between the third cross member 12t on the rear edge side of the front cover wall 42 and the connection between the first cross member 12f on the front edge side of the front cover wall 42 are all positioned offset in the vehicle width direction.

[0040] As described above, in this embodiment, the front and rear edges of the cover wall 42 of the battery module 7 of the battery unit 5 are connected to two adjacent cross members (the third cross member 12t and the second cross member 12s, and the third cross member 12t and the first cross member 12f). Therefore, when an impact load is applied to one of the frame members 11 from one side in the vehicle width direction, the impact load transmitted to the adjacent cross member is efficiently transmitted to the other cross member through the cover wall 42. As a result, the applied impact load is efficiently distributed and supported by multiple cross members through the cover wall 42.

[0041] Furthermore, in the battery unit 5 of this embodiment, one of the adjacent cross members (the third cross member 12t) has a multi-rib structure 51 and a single rib section 52 that are interconnected in the vehicle width direction, and the front-rear edge of the cover wall 42 is connected near the point where the number of ribs 50 in the multi-rib structure 51 changes from two to one. As a result, the impact load transmitted to the multi-rib structure 51 of the third cross member 12t is transmitted to the cover wall 42 through a section that is relatively prone to outward movement in response to the input load. Consequently, the impact load input to the third cross member 12t is efficiently transmitted to the first cross member 12f and the second cross member 12s through the cover wall 42. Therefore, when the battery unit 5 of this embodiment is adopted, it becomes possible to efficiently absorb the input impact load using the cover wall 42 without increasing the number of cross members or making the cross members larger. Thus, the input impact load can be efficiently absorbed by parts other than the battery cells 6 while avoiding an increase in the size and weight of the battery housing case 10.

[0042] Furthermore, in the battery unit 5 of this embodiment, the third cross member 12t, which has a multi-rib structure 51 and a single rib section 52, is provided with a widened section 45 whose front-to-back width gradually increases toward the fixing section 44 with the frame member 11. Therefore, an impact load input to one of the frame members 11 from one side in the vehicle width direction is transmitted from the fixing section 44 with the frame member 11 of the third cross member 12t through the widened section 45 to the multi-rib structure 51 and the single rib section 52. At this time, since the front-to-back width of the widened section 45 gradually decreases toward the multi-rib structure 51 and the single rib section 52 toward the fixing section 44 with the frame member 11, the load input from the frame member 11 to the third cross member 12t is more easily transmitted to the multi-rib structure 51 and the single rib section 52. As a result, the impact load input to the third cross member 12t is more easily transmitted by the first cross member 12f and the second cross member 12s via the cover wall 42. Furthermore, an impact load input from one side of the third cross member 12t is transmitted to the other frame member 11 through the widened portion 45 on the other side of the third cross member 12t. At this time, since the width of the widened portion 45 on the other side gradually increases toward the fixing portion 44 with the other frame member 11, the impact load is stably received by a wide area in the front-rear direction of the other frame member 11. Therefore, when the battery unit 5 of this embodiment is adopted, the input shock load can be absorbed more efficiently by parts other than the battery cell.

[0043] Furthermore, in this embodiment, the battery unit 5 is provided with a fastening boss portion 54 via a pair of reinforcing ribs 53 extending in the front-rear direction, near the point where the number of ribs 50 in the multi-rib structure portion 51 of the third cross member 12t changes from two to one. Therefore, the impact load input to the multi-rib structure portion 51 of the third cross member 12t can be efficiently transmitted to the cover wall 42 through the pair of reinforcing ribs 53.

[0044] Furthermore, in the battery unit 5 of this embodiment, a separation space S is secured between the frame member 11 and the adjacent battery module 7, spaced apart in the vehicle width direction. When an impact load is applied to one of the frame members 11 from one side in the vehicle width direction, the impact load is absorbed by the multiple cross members and the cover wall 42 of the battery module 7. At this time, even if a part of one of the frame members 11 is displaced inward in the vehicle width direction, the separation space S is secured between the frame member 11 and the battery module 7, making it difficult for the load to be directly transmitted from the frame member 11 to the battery module 7. Therefore, when the battery unit 5 of this embodiment is adopted, it becomes possible to protect the battery cell 6 more advantageously when an impact load is applied.

[0045] Furthermore, in the battery unit 5 of this embodiment, two adjacent cross members (the third cross member 12t and the second cross member 12s, and the third cross member 12t and the first cross member 12f) are each connected to the edge of the cover wall by fastening bosses 54 and 65 that are positioned offset from each other in the vehicle width direction. Therefore, when an impact load is applied to one of the frame members from one side in the vehicle width direction, the load is absorbed by the two adjacent cross members and also by the cover wall 42. At this time, the fastening bosses 54 and 65, which are the points where the load is transmitted from the two cross members to the cover wall 42, are positioned offset from each other in the vehicle width direction. Consequently, when the battery unit 5 of this embodiment is adopted, the cover wall 42 is less likely to bend or deform when an impact load is applied, and the impact load can be efficiently absorbed by the cover wall 42.

[0046] It should be noted that the present invention is not limited to the embodiments described above, and various design modifications are possible without departing from the spirit of the invention. In the embodiments described above, three cross members are provided spaced apart in the front-rear direction and connected to a pair of skeletal members 11, but the number of cross members is not limited to three. The number of cross members may be four or more, or two or fewer.

[0047] Furthermore, in the above embodiment, a pair of frame members 11 extend along the longitudinal direction of the vehicle body and are spaced apart from each other in the vehicle width direction, and the first, second, and third cross members 12f, 12s, and 12t are arranged along the vehicle width direction. However, the arrangement of the frame members and cross members is not limited to this. For example, a pair of frame members may be arranged to extend along the vehicle width direction and be spaced apart from each other in the longitudinal direction of the vehicle body, and the cross members may be arranged along the longitudinal direction of the vehicle body.

[0048] Furthermore, in the above embodiment, the multi-rib structure 51 and the single rib section 52 are provided on only one of the adjacent cross members, but the multi-rib structure 51 and the single rib section 52 may be provided on both adjacent cross members in the same manner.

[0049] Furthermore, although the multi-rib structure 51 in the above embodiment is shaped such that one rib 50 branches into two from one side in the extending direction toward the other side and then rejoins into one, the multi-rib structure 51 may also be shaped such that one rib 50 branches into three or more from one side in the extending direction toward the other side and then rejoins into one. [Explanation of Symbols]

[0050] 3…Side sill (framework component) 5…Battery unit 6…Battery cell 7…Battery module 10…Battery housing case 11...Skeletal Members 12f...First cross member (cross member) 12s…Second cross member (cross member) 12t... Third cross member (cross member) 40... Module case 42... Cover wall 44…Fixed part 45... Widening section 50... Rib 51…Multi-rib structure 52...Single rib section 53…Reinforcement ribs 54…Boss portion for fastening (connecting portion) 65…Boss portion for fastening (connecting portion) S... Separation space

Claims

1. A battery module in which battery cells are housed in a module case, The system comprises a battery housing case attached to the vehicle's frame member, in which the battery module is housed, The aforementioned battery housing case is A pair of skeletal members extending along a first direction substantially perpendicular to the vertical direction, It comprises a plurality of cross members that extend in the vertical direction and in a second direction substantially perpendicular to the first direction, with both ends in the extending direction connected to a pair of the skeletal members, The module case comprises a cover wall that covers the top of the battery cell and whose edges on both sides in the first direction are connected to two adjacent cross members, respectively. At least one of the adjacent cross members is A multi-rib structure in which a single rib branches out from one end to the other end in the second direction, then branches out into multiple ribs in the first direction, and then merges back into a single rib, It has a single rib portion that extends along the second direction, and whose end in the extending direction is connected to the multi-rib structure, The battery unit of a vehicle is characterized in that the edge of the cover wall is in the vicinity of the portion where the number of ribs in the multi-rib structure changes from multiple to one, and is connected to the ribs in the portion where there are multiple ribs.

2. The vehicle battery unit according to claim 1, characterized in that the cross member having the multi-rib structure and the single rib portion has a widening portion in which the width in the first direction gradually increases in a widening manner toward the fixing portion with the skeletal member.

3. The battery unit for a vehicle according to claim 1, characterized in that a connection portion to the cover wall is provided via a plurality of reinforcing ribs extending along the first direction near the portion where the number of ribs in the multi-rib structure of the cross member changes from multiple ribs to one.

4. The battery unit for a vehicle according to claim 2, characterized in that a separation space is provided between the frame member and the battery module, separating in the second direction.

5. The battery unit for a vehicle according to claim 1, characterized in that the two adjacent cross members have their connecting portions to the cover wall at positions offset from each other in the second direction.

Images