Battery case

Abstract

To provide a battery case which can reduce the manufacturing cost.SOLUTION: In a battery case (10) mainly formed of a bottom plate (12) and a side frame (20), the side frame (20) includes a recessed part (27) formed of an L-shaped cross sectional part (23), and an inner closed cross sectional part (24) and an outer closed cross sectional part (25) forming a closed space, surrounded by the L-shaped cross sectional part (23), the inner closed cross sectional part (24), and the outer closed cross sectional part (25), and having an open bottom. The thus-formed side frame (20) is formed of a single metal plate. The bottom plate (12) may be a flat plate.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery case for housing a battery. [Background technology]

[0002] In so-called electric vehicles, a large number of drive batteries (hereinafter, abbreviated as batteries) are arranged under the floor. The large number of batteries are generally provided in the vehicle in a state of being housed in a battery case.

[0003] 2. Description of the Related Art Conventionally, battery cases of various structures have been known (see, for example, Patent Document 1 (FIG. 1)).

[0004] Patent Document 1 will be explained with reference to the following figure. 12(a) and (b) are diagrams illustrating the basic structure of a conventional battery case. As shown in FIG. 12(a), battery case 100 mainly comprises deep dish-shaped case body 101, also known as a bathtub shape, and left and right side frames 111 attached to case body 101 as indicated by the white arrows.

[0005] Case body 101 is manufactured by deep drawing a metal plate called a blank using a press molding machine (hereinafter abbreviated as "press"). As a result, case body 101 consists of bottom 102, wall 103 standing up from bottom 102, and flange 104 extending horizontally outward from the upper end of wall 103.

[0006] The side frame 111 is formed by subjecting a single flat metal plate to plastic processing. The term "plastic processing" refers to processing that causes plastic deformation, and "plastic deformation" refers to deformation that does not return to its original state even when an external force is released. Next, the two plates are joined together at their overlapping portions by spot welding or the like.

[0007] Hereinafter, the nugget formed by spot welding and the weld bead formed by continuous welding will be collectively referred to as the weld metal. That is, weld metals 112 and 113 are recognized at the joint.

[0008] As a result, a side frame 111 is obtained, which has a first closed cross-sectional portion 115, a second closed cross-sectional portion 116, and an upper flange 117. Note that an opening 119 for inserting a welding torch is provided in advance in the second closed cross-sectional portion 116.

[0009] The obtained side frame 111 is applied to the case body 101 according to the outline arrow. 12(b), the side frame 111 is joined to the case body 101 at the circled locations. Deposited metals 121, 122 are found at the joining locations.

[0010] Through the above steps, a battery case 100 with a preferable structure is obtained. Although the battery case 100 according to Patent Document 1 described with reference to FIGS. 12(a) and (b) has a preferable structure, there are some points that require further improvement. First, the opening 119 is generally formed by punching. That is, a punching process is added to the roll forming (or press molding) process, and the manufacturing cost of the side frame 111 increases.

[0011] Secondly, the case body 101 is deep-drawn, which requires a die dedicated to deep drawing. If the drawing ratio is too large, there is a risk that the case body 101 will tear during the drawing process. Therefore, it is recommended to draw it gradually in multiple steps. In this case, multiple dies are required. Case body 101 requires advanced processing technology, and in addition, the cost of the mold is high, so the manufacturing cost of case body 101 is high.

[0012] As electric vehicles become more widespread, there is a demand for reducing the cost of battery cases as part of efforts to reduce the cost of electric vehicles. In order to meet this demand, a battery case that can improve on the first and second points described above is desired. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Publication No. 2022 / 249782 Brochure Summary of the Invention [Problem to be solved by the invention]

[0014] An object of the present invention is to provide a battery case that can reduce manufacturing costs. [Means for solving the problem]

[0015] The invention according to claim 1 is a battery case comprising a bottom plate supporting a battery, side walls surrounding the battery placed on the bottom plate, and a top lid placed over the side walls to cover the battery, The bottom plate is a flat plate, The side walls have a rectangular frame structure in a plan view, the frame structure including left and right side frames, a front frame extending between front ends of the left and right side frames, and a rear frame extending between rear ends of the left and right side frames, The side frame is composed of an L-shaped cross-sectional portion, an inner closed cross-sectional portion and an outer closed cross-sectional portion that form a closed space in a cross-sectional view, The L-shaped cross-sectional portions are arranged vertically on the bottom plate, The inner closed cross-sectional portion is disposed on the L-shaped cross-sectional portion, the outer closed cross-sectional portion is disposed outside the inner closed cross-sectional portion so as to be spaced apart from the bottom plate, and is disposed below the inner closed cross-sectional portion; a recess surrounded by the L-shaped cross-sectional portion, the inner closed cross-sectional portion, and the outer closed cross-sectional portion and having an open bottom, The side frame having such a structure is characterized in that it is formed from a single metal plate.

[0016] The invention according to claim 2 is the battery case according to claim 1, A cross member extending from the left side frame to the right side frame is further provided, and a connecting bracket is further provided to connect the cross member to the left and right side frames, the connecting bracket is triangular in plan view having a vertex, and includes a base portion that abuts against the left and right side frames, and a pair of oblique sides that extend from both ends of the base portion to the vertex, and includes a storage recess at the vertex for storing the ends of the left and right side frames; The housing recess has a space surrounded by the pair of oblique sides and the bottom side.

[0017] The invention according to claim 3 is the battery case according to claim 2, The bottom plate has a reinforcing material on the lower surface thereof, The reinforcing member is disposed at a position where the bottom plate is sandwiched between the reinforcing member and the cross member, The end of the reinforcing member is an extension that protrudes from the bottom plate, The extension portion is characterized in that it extends to the middle of the recess so as to face the outer closed cross-sectional portion.

[0018] The invention according to claim 4 is the battery case according to claim 2, The cross member is made up of a plurality of members, a cooling plate is disposed between the front and rear cross members, and piping for supplying and discharging a coolant to the cooling plate is disposed in the recess.

[0019] The invention according to claim 5 is the battery case according to claim 1, the side frame is a roll product formed by roll forming, and the inner closed cross-sectional portion includes an inner wall portion extending upward from the L-shaped cross-sectional portion, an arc portion connected to an upper end of the inner wall portion, and a ceiling portion extending outward from a tip of the arc portion, the front frame and the rear frame are press-formed products, and include at least a wall frame portion standing upright from the bottom plate and a ceiling frame portion extending horizontally from an upper end of the wall frame portion; The ceiling frame portion is characterized in that a tongue piece is integrally formed which extends beyond the arc portion to the ceiling portion and is joined to the ceiling portion.

[0020] The invention according to claim 6 is the battery case according to claim 4, In addition to the cooling plate, the battery case includes a front cooling plate and a rear cooling plate, the front frame has a flange connection portion to which a front edge portion of the front cooling plate can be welded; The rear frame has a flange connection portion to which a rear edge portion of the rear cooling plate can be welded.

[0021] The invention according to claim 7 is the battery case according to claim 4, a bottom surface of the outer closed cross-sectional portion is disposed at a lower position than a lower surface of the cooling plate; the front frame and the rear frame each have a lower surface protrusion that protrudes downward, and the lower surface protrusion is aligned at the same level as a bottom surface of the outer closed cross-sectional portion; The battery case further includes a protective plate for protecting the cooling plate, The protective plate is characterized in that it is detachably connected to the bottom surface of the outer closed cross-sectional portion and the lower surface protrusion by means of a screw via a sealing material.

[0022] The invention according to claim 8 is the battery case according to claim 7, The side frame is characterized in that its rear end is closed by a rear fastening member.

[0023] The invention according to claim 9 is the battery case according to claim 8, The rear fastening member has a bottom surface to which the sealant is applied, the bottom surface traversing the recess in a bottom view.

[0024] The invention according to claim 10 is the battery case according to claim 7, The side frame is made of an aluminum alloy, and the bottom surface of the outer closed cross-sectional portion is subjected to plasma treatment or laser treatment before coming into contact with the sealing material.

[0025] The invention according to claim 11 is the battery case according to claim 1, The side frame is made of an aluminum alloy and is bonded to the bottom plate by an adhesive. The L-shaped cross-sectional portion of the side frame is characterized in that it is subjected to plasma treatment or laser treatment before coming into contact with the adhesive.

[0026] The invention according to claim 12 is the battery case according to claim 1, The side frame is made of a single metal plate, with an annular bent portion forming an outer closed cross-sectional portion, and a U-shaped bent portion and a shielding plate portion that blocks the opening forming an inner closed side portion. Effect of the Invention

[0027] In the invention according to claim 1, the bottom plate is a flat plate and no die is required for deep drawing the bottom plate, so that the manufacturing costs of the bottom plate can be significantly reduced. The side frame, which is the main part of the side wall, is manufactured from a single metal plate by roll forming or press molding. Since the lower end of the L-shaped cross section of the side frame is simply stacked and joined to the bottom plate, no opening is required to insert a welding torch, and no punching process is required, which reduces the manufacturing cost of the side frame.

[0028] In addition, the side frame of the present invention has an outer closed cross-sectional portion that protrudes outward from the inner closed cross-sectional portion, and when an object collides with the side from the left or right, the outer closed cross-sectional portion crushes and deforms and enters the recess below the inner closed cross-sectional portion, and as the collision progresses, the inner closed cross-sectional portion and the outer closed cross-sectional portion crush and deform, absorbing the collision energy and protecting the internal battery. Therefore, the present invention provides a battery case that can adequately protect the battery from side impacts and can reduce manufacturing costs. Because the side frames are formed from a single metal plate, the impact absorption performance can be controlled simply by changing the plate thickness.

[0029] In the invention according to claim 2, the cross member is placed between the left and right side frames via the connecting bracket, and the connecting bracket has a space portion with a sufficiently large volume in a plan view. In the event of a side collision, the connecting bracket is crushed and plastically deformed, absorbing the collision energy and protecting the battery. Roll-form molding is possible, so side frame roll-form equipment can be used.

[0030] In the invention according to claim 3, a reinforcing material is provided under the bottom plate, the end of which protrudes from the bottom plate and extends to the middle of the recess so that the protruding extension faces the outer closed cross-sectional portion. In the primary side impact, the outer closed cross-section portion is crushed and deformed, but in the secondary side impact, the extension of the reinforcement material undergoes plastic deformation and absorbs the collision energy. Therefore, in addition to the crushing of the outer closed cross-sectional portion, the extension portion undergoes plastic deformation, making it possible to absorb a large amount of collision energy.

[0031] In the invention according to claim 4, the piping is arranged in the recessed portion, and since the recessed portion is open downward, the piping can be easily attached, detached, and maintained / inspected.

[0032] In the invention according to claim 5, an arc portion is included at the upper inner corner of the side frame. By including the arc portion, plastic processing of the side frame becomes easier. The larger the radius of curvature of the arc portion, the easier the processing becomes. However, the larger the radius of curvature of the arc portion, the more difficult it becomes to join the upper part of the side frame and the upper part of the front frame (or rear frame). Therefore, in claim 5, tongue pieces that extend beyond the arc portions are integrally formed with the front and rear frames. By using these tongue pieces, the upper parts of the side frames and the upper parts of the front frame (or rear frame) can be easily joined together.

[0033] In the invention of claim 6, the front frame has a flange connection portion to which the front edge portion of the front cooling plate can be welded, and the rear frame has a flange connection portion to which the rear edge portion of the rear cooling plate can be welded. A front edge of the front cooling plate can be welded to the front frame via flange connections, and a rear edge of the rear cooling plate can be welded to the rear frame via flange connections. That is, according to the present invention, the front cooling plate and the rear cooling plate can be reliably supported without drilling holes.

[0034] In the invention according to claim 7, the battery case further includes a protective plate for protecting the cooling plate, and this protective plate is detachably connected to the bottom surface of the outer closed cross-sectional portion and the lower protrusion portion by screws via a sealing material. The presence of the sealing material makes it possible to prevent water and soil from entering between the protective plate and the outer closed cross-sectional portion (or the lower surface protruding portion). By loosening the screws, the protective plate can be easily removed from the battery case, facilitating installation, removal, and maintenance of the cooling plate.

[0035] In the invention according to claim 8, the rear end of the side frame is closed by a rear fastening member. The side frame can be reinforced by the rear fastening member. The rear fastening member can also be used to connect the battery case to the inside of the vehicle body.

[0036] In the invention according to claim 9, a sealant is applied to the bottom surface of the rear fastening member. Despite the presence of the recess, the existence of the bottom surface makes it possible to apply the sealant without interruption. Further, although a separate member (a temporary bridge) may be provided across the recess, this requires a separate member, which may increase the number of parts and manufacturing costs. In this regard, in the present invention, by making ingenious use of the bottom surface of the rear fastening member, an increase in the number of parts is suppressed, and an increase in manufacturing costs is also suppressed.

[0037] In the invention according to claim 10, the side frame is made of an aluminum alloy, and the bottom surface of the outer closed cross-sectional portion is subjected to plasma treatment or laser treatment before coming into contact with the sealing material. The surface of the aluminum alloy is activated by the plasma treatment or laser treatment, which promotes adhesion between the sealing material and the aluminum alloy and inhibits long-term deterioration due to high humidity.

[0038] In the invention according to claim 11, the side frame is made of an aluminum alloy, and the L-shaped cross-section of the side frame is subjected to plasma treatment or laser treatment before coming into contact with the adhesive. The surface of the aluminum alloy is activated by plasma treatment or laser treatment, which promotes adhesion between the adhesive and the aluminum alloy and inhibits long-term deterioration due to high humidity.

[0039] In the invention of claim 12, an outer closed cross-section is formed by bending a single metal plate into an annular shape, and an inner closed side is formed by a U-shaped bent portion and a shielding plate portion that covers the opening, so that a large number of highly strong closed cross-sections can be easily obtained for battery cases to be placed under the floor of a vehicle. [Brief description of the drawings]

[0040] [Figure 1] FIG. 2 is an exploded perspective view of the battery case according to the present invention. [Diagram 2] 1A is a cross-sectional view of the side frame after plastic working, FIG. 1B is a cross-sectional view of the side frame after joining, and FIG. 1C is a diagram showing the action during a side collision. [Diagram 3] 13(a) and 13(b) are cross-sectional views showing modified examples of the side frame. [Figure 4] 4(a) is an enlarged plan view of a connecting bracket of a portion 4a in FIG. 1, and FIG. 4(b) is an operation diagram of the connecting bracket. [Diagram 5]1A is an exploded view showing the reinforcing material and cooling plate attached to the bottom plate, FIG. 1B is a plan view of the main parts after the reinforcing material is attached to the bottom plate, FIG. 1C is a cross-sectional view along line cc in FIG. 1B, and FIG. 1D is a view taken along arrow d in FIG. 1A. [Figure 6] FIG. 4A is a diagram for explaining the positional relationship between the reinforcing material and the outer closed cross-sectional portion, and FIG. 4B is a diagram for explaining the function of the extension portion. [Figure 7] 1A is a cross-sectional view showing a pipe housed in a recess, and FIG. 1B is a view taken along the arrow bb in FIG. [Figure 8] 1A is a cross-sectional view of the rear frame, FIG. 1B is an enlarged view of part b in FIG. 1A, and FIG. 1C is a view taken along the arrow cc in FIG. [Figure 9] 1A is an enlarged plan view of part 9a in FIG. 1, and FIG. [Figure 10] FIG. 13(a) is a perspective view showing the rear end of the side frame, and (b) is a perspective view illustrating a rear fastening member. [Figure 11] 13(a) to 13(c) are diagrams illustrating modified examples of the side frame. [Figure 12] 1A and 1B are diagrams illustrating the basic configuration of a conventional battery case. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. In the attached drawings, the directions such as front / rear, left / right, and up / down are determined based on the driver operating the vehicle, assuming that the battery case of the present invention is mounted on a vehicle. EXAMPLES

[0042] [Battery case] As shown in FIG. 1, the battery case 10 comprises a bottom plate 12 that supports the battery 11, a side wall 13 that has a peripheral wall shape and surrounds the battery 11 placed on the bottom plate 12, and a top lid 14 that is placed on the side wall 13 to cover the battery 11. Preferably, a protective plate 16 is attached under the bottom plate 12. The top cover 14 and the protective plate 16 are detachably attached to the side wall 13, but the bottom plate 12 is joined to the side wall 13 by welding (or adhesive).

[0043] The side wall 13 is made up of left and right side frames 20, a front frame 40 that connects the front ends of the left and right side frames 20, and a rear frame 80 that connects the rear ends of the left and right side frames 20, forming a substantially rectangular frame structure in a plan view. In the embodiment, the width narrows toward the front, but it may be a regular square or rectangle. The bottom plate 12 is a flat plate. The flat plate may be a completely flat plate or a plate that locally includes small irregularities of about 10 mm or less (i.e., a nearly flat plate), and in short, it is sufficient that the plate is macroscopically flat.

[0044] Preferably, a plurality of (eg, four) cross members 42 extending in the vehicle width direction are disposed between the left and right side frames 20. Preferably, the rear end of the side frame 20 is closed with a rear fastening member 44. This member is referred to as the rear fastening member 44 because it is a block that is disposed at the rear and is used when fastening the battery case 10 to the inside of the side sill of the vehicle body with bolts or the like. Each component will be described in detail below.

[0045] [Side frame] 2(a) is a cross-sectional view of a semi-finished frame 21 after plastic working during the manufacturing process of a side frame. A single metal plate called a blank is subjected to plastic working by roll forming to obtain a semi-finished frame 21 with a cross section that resembles a single stroke of a line. The blank may be an aluminum alloy, a steel plate, or a tailored blank material.

[0046] The semi-finished frame 21 is compressed from the left and right to overlap the plates. Next, the overlapping portions are welded. The welding method is preferably MIG welding, TIG welding, or laser beam welding, but spot welding or other welding methods may also be used. By performing welding, the side frame 20 is obtained.

[0047] Specifically, as shown in Figures 2(a) and (b), the obtained side frame 20 is formed by roll-forming a single metal plate to form an L-shaped cross-sectional portion 23, which extends upward and is folded back to form U-shaped bent portions 24a, 24b downward. The L-shaped cross-sectional portion 23 and the welded metal 22 are then welded to the L-shaped cross-sectional portion 23 to form one closed cross section of the inner closed cross-sectional portion 24. The outer side is then welded with the welded metal 22 to form an annular bent portion 25a to constitute the outer closed cross-sectional portion 25 of one closed cross section. Finally, the opening is closed as a shielding plate portion 25b spanning the U-shaped bent portion 24b, and the end portion is welded with the welded metal 22 to form one closed cross section. This and the previous closed cross section form the inner closed cross-sectional portion 24 of the two closed side portions.

[0048] In this way, by folding with roll forming and welding with deposited metal 22, a single metal plate is formed with annular folded portion 25a to form outer closed cross-sectional portion 25, and U-shaped folded portions 24a, 24b and shielding plate portion 25b that closes the opening to form inner closed side portion 24, so that a battery case to be placed under the floor of an automobile can be easily obtained with multiple closed cross-sections with high strength. Therefore, the shape and rigidity of the battery case are ensured, and in cross section, it is composed of an L-shaped cross-sectional portion 23, an inner closed cross-sectional portion 24 formed by a closed space, and an outer closed cross-sectional portion 25 formed by a closed space.

[0049] The L-shaped cross-sectional portion 23 is disposed on the bottom plate (FIG. 2(c), reference numeral 12). An inner closed cross-sectional portion 24 is disposed on top of this L-shaped cross-sectional portion 23. The outer closed cross-sectional portion 25 is disposed below this inner closed cross-sectional portion 24. The bottom surface 26 of the outer closed cross-sectional portion 25 is positioned sufficiently below the lower end level of the L-shaped cross-sectional portion 23.

[0050] The outer closed cross-sectional portion 25 is disposed outside the inner closed cross-sectional portion 24 so as to be spaced apart from the bottom plate (FIG. 2(c), reference numeral 12). A recess 27 is provided which is surrounded by the L-shaped cross-sectional portion 23, the inner closed cross-sectional portion 24 and the outer closed cross-sectional portion 25 and has an open bottom.

[0051] In this type of battery case 10, it is necessary to take measures to prevent damage to the battery when the vehicle collides with another vehicle or with an obstacle on the road. Therefore, as shown in FIG. 2(c), it is assumed that an obstacle on the road is a pole 28, and the side of the vehicle collides with this pole 28 (hereinafter, abbreviated as a side collision). Since the outer closed cross-sectional portion 25 protrudes outward more than the inner closed cross-sectional portion 24, the outer closed cross-sectional portion 25 first collides with the pole 28. Due to this collision, the outer closed cross-sectional portion 25 is deformed so as to enter the recess 27 while being crushed. This deformation absorbs part of the collision energy.

[0052] If the collision progresses further, the inner closed cross-sectional portion 24 and the outer closed cross-sectional portion 25 are crushed and deformed to absorb the collision energy and protect the battery inside. Therefore, the present invention provides a battery case that can adequately protect the battery from side impacts and can reduce manufacturing costs. Since the side frame is formed from a single metal plate, the impact absorption performance can be controlled simply by changing the plate thickness.

[0053] Furthermore, as shown in FIG. 2(c), when joining the side frame 20 and the bottom plate 12, the bottom plate 12 is placed against the L-shaped cross-sectional portion 23 of the side frame 20 (or the L-shaped cross-sectional portion 23 is placed on the bottom plate 12), welding is performed, and the two are joined together with the weld metal 29 (or adhesive). That is, when joining the side frame 20 to the bottom plate 12, there is no need to provide an opening in the side frame 20 for inserting a welding torch.

[0054] If openings are provided in the side frames 20, the openings will be provided by punching, and the punching process will be added to the bending process by roll forming, so the processing costs of the side frames 20 will increase. In this regard, according to the present invention, since no opening is required, an increase in the manufacturing cost of the side frame 20 can be suppressed.

[0055] In addition, as described in FIG. 1, the bottom plate 12 may be a flat plate. If bottom plate 12 were to be deep drawn, a special mold (deep drawing mold, large mold) and a large press would be required, and if deep drawing was to be performed in multiple steps, multiple special molds would be required, resulting in increased manufacturing costs for bottom plate 12. In this regard, according to the present invention, the bottom plate 12 may be a flat plate, so that a special mold is not required, and an increase in the manufacturing cost of the bottom plate 12 can be suppressed.

[0056] [Modification of side frame] In Figures 3(a) and (b), elements common to Figures 2(a) and (b) are designated by the same reference numerals as in Figures 2(a) and (b), and detailed explanations thereof will be omitted. 3(a) and (b), the semi-finished frame 21 has a cross section drawn in one stroke. Specifically, the side frame 21 is formed by roll forming a single metal plate to form an L-shaped cross section 23, extending upward and folding back to form a U-shaped bent section 24a, and then wrapping around the outside of the U-shaped bent section 24a below and welding it with the weld metal 22 to form an annular bent section 25a to form an outer closed cross section 25 of one closed cross section, then forming a U-shaped bent section 24b upward and welding the bottom to the L-shaped cross section 23 with the weld metal 22, and then butting an end against the shielding plate section 25b and welding it with the weld metal 22 to form two closed cross sections, the inner closed cross section 24, so that a battery case to be placed under the floor of an automobile can be easily obtained with a large number of closed cross sections with high strength.

[0057] Therefore, as shown in FIG. 3(b), the side frame 20, whose shape and rigidity are maintained by being welded with the deposited metal 22 of the battery case, is composed, in a cross-sectional view, of an L-shaped cross-sectional portion 23, an inner closed cross-sectional portion 24 that forms a closed space, and an outer closed cross-sectional portion 25 that also forms a closed space.

[0058] An inner closed cross-sectional portion 24 is disposed on the L-shaped cross-sectional portion 23 . The outer closed cross-sectional portion 25 is disposed below this inner closed cross-sectional portion 24. The bottom surface 26 of the outer closed cross-sectional portion 25 is positioned sufficiently below the lower end level of the L-shaped cross-sectional portion 23.

[0059] The outer closed cross-sectional portion 25 is disposed outside the inner closed cross-sectional portion 24 so as to be spaced apart from the bottom plate (FIG. 2(c), reference numeral 12). A recess 27 is provided which is surrounded by the L-shaped cross-sectional portion 23, the inner closed cross-sectional portion 24 and the outer closed cross-sectional portion 25 and has an open bottom.

[0060] As is clear from the above explanation, the side frame 20 of the present invention may be a side frame 20 having a cross section shown in FIG. 2(b) or a side frame 20 having a cross section shown in FIG. 3(b). In short, as long as the L-shaped cross-sectional portion 23, the inner closed cross-sectional portion 24, the outer closed cross-sectional portion 25 and the recess 27 are provided in predetermined positions, the cross-sectional structure may be changed.

[0061] [Connecting bracket] FIG. 4(a) is an enlarged view of portion 4a in FIG. As shown in FIG. 4( a ), the cross member 42 is connected to the side frame 20 using a connecting bracket 50 . The connecting bracket 50 has the shape of an isosceles triangle having a vertex 51 in a plan view, and consists of a base portion 52 that abuts against the side frame 20, and a pair of oblique portions 53 extending from both ends of the base portion 52 to the vertex 51. By making the base portion 52 and the oblique portions 53 a predetermined thickness, a large-volume space portion 54 is formed inside.

[0062] In addition, a storage recess 55 for storing the end of the side frame 20 is provided near the apex 51. As a result, a space 54 is formed between the storage recess 55 and the bottom portion 52 . The bottom position of the storage recess 55 may be set arbitrarily.

[0063] For example, the bottom position of the storage recess 55 may be aligned with the center of gravity 56 of an isosceles triangle. Most of the axial force of the cross member 42 is applied to the center of gravity 56. When an external force is applied to the center of gravity 56, the triangular connecting bracket 50 is most stable. As a result, the axial force is transmitted to the side frame 20 in a stable manner.

[0064] Furthermore, when the height of the isosceles triangle is H and the distance from the base to the center of gravity is h, the center of gravity 56 is determined by the formula h=1 / 3H. As a result, the space 54 has a sufficient capacity.

[0065] As shown in FIG. 4( b ), when the cross member 42 moves along the outline arrow due to a side collision, the pair of oblique sides 53 deform and the storage recess 55 approaches the bottom side 52 . By deforming the oblique side portion 53, part of the collision energy is absorbed, protecting the built-in battery (FIG. 1, reference numeral 11). Even if the pole collision occurs at a position slightly shifted from the axis of the cross member 42, the space portion 54 can tolerate the shift.

[0066] [Reinforcement material] As shown in FIG. 5(a), a plurality of reinforcing members 60 are prepared for one bottom plate 12. 5(b), a reinforcing member 60 is fastened to the bottom plate 12 by a fastener 61 such as a rivet or a bolt. In this way, the bottom plate 12 is reinforced by the reinforcing member 60. 5(c), the reinforcing member 60 is preferably disposed directly below the cross member 42. That is, the reinforcing member 60 is disposed at a position where the bottom plate 12 is sandwiched between the reinforcing member 60 and the cross member 42.

[0067] [Extension] As shown in FIG. 5( b ), the end of the reinforcing member 60 is an extension 62 that protrudes from the bottom plate 12 . As shown in FIG. 5(c), the reinforcing material 60 comprises a flat central portion 63, falling portions 64 that slope diagonally downward from both ends of the central portion 63, and horizontal portions 65 that extend horizontally from the lower ends of the falling portions 64. As shown in FIG. 5( d ), the horizontal portion 65 is extended to form an extension portion 62 integrally therewith, and the tip of the extension portion 62 is bent upward to form an upright wall 66 .

[0068] 6(a), the extension 62 is extended to the middle (almost the center) of the recess 27 so as to face the outer closed cross-sectional portion 25. A pipe 75 shown by an imaginary line is housed in the recess 27. In this case, the extension 62 is extended to a position beyond the pipe 75. In other words, the standing wall 66 is disposed outside the pipe 75. Even in this case, a certain gap is provided between the outer closed cross-sectional portion 25 and the standing wall 66.

[0069] 2(c), in the event of a side collision, the outer closed cross-sectional portion 25 is crushed and enters the recess 27. If the side collision is minor, the piping 75 is protected by the extension portion 62 shown in FIG. If the side impact is severe, the outer closed cross-sectional portion 25 is crushed in the early stage of the side impact, and in the later stage of the side impact, as shown in Fig. 6(b), the crushed outer closed cross-sectional portion 25 kicks up the standing wall 66. Then, the extension portion 62 is deformed while being bent as a whole. This deformation of the extension portion 62 absorbs part of the collision energy. If the collision continues or becomes severe, the inner closed cross-sectional portion 24 will be crushed and deformed to absorb part of the collision energy.

[0070] As described above, according to the side frame 20 of the present invention, in the first stage of a side collision, the outer closed cross-section portion 25 collapses to absorb the collision energy, in the second stage of the side collision, the extension portion 62 deforms to absorb the collision energy, and in the third stage of the side collision, the inner closed cross-section portion 24 deforms to absorb the collision energy. Therefore, the battery (11 in FIG. 1) is well protected against a side impact.

[0071] [Cooling plate] 5(a), a cooling plate 70 is disposed at a position sandwiched between the front and rear cross members 42. The cooling plate 70, also called a cooling jacket, is composed of a hollow plate body 71 through which a coolant such as cooling water flows, an inlet 72 provided at one end of the plate body 71 through which the coolant is supplied, an outlet 73 provided at the other end of the plate body 71 through which the coolant is discharged, and a flange 74 extending from the plate body 71.

[0072] 5(c), the cooling plate 70 is closely attached to the lower surface of the bottom plate 12, and the flange 74 is joined to the bottom plate 12 by, for example, welding. If the joining becomes incomplete for some reason and the cooling plate 70 falls, the horizontal part 65 of the reinforcing member 60 serves to prevent the cooling plate 70 from falling. When an obstacle on the road approaches the cooling plate 70, the horizontal portion 65 hits the obstacle on the road due to so-called "bottoming out," and the cooling plate 70 is protected.

[0073] Piping As shown in FIG. 7( a ), a pipe 75 is provided corresponding to an inlet 72 (or an outlet 73 ) of a cooling plate 70 , and this pipe 75 is housed in a recess 27 . As described above, the cross members 42 are made up of a plurality of pieces, the cooling plate 70 is disposed between the front and rear cross members 42, and the pipes 75 for supplying and discharging the coolant to the cooling plate 70 are disposed in the recess 27. By simply removing the protective plate 16, the bottom of the recess 27 is opened, allowing easy installation and removal of the pipe 75 and easy maintenance and inspection.

[0074] [Arc section] As shown in Fig. 2(b), the inner closed cross-sectional portion 24 includes an inner wall portion 31 extending upward from the L-shaped cross-sectional portion 23, an arc portion 32 connected to the upper end of the inner wall portion, and a ceiling portion 33 extending horizontally outward from the tip of the arc portion 32. The arc portion 32 will be described in detail in Fig. 9(b).

[0075] [Back Frame] The front frame 40 and the rear frame 80 shown in FIG. 1 have the same (or substantially the same) cross-sectional structure, so the rear frame 80 will be described in detail below. As shown in FIG. 8(a), the rear frame 80 is made up of a first L-shaped cross-section member 81 on the front side and a second L-shaped cross-section member 82 on the rear side. The first L-shaped section 81 is a pressed product obtained by press forming, and the second L-shaped section 82 is also a pressed product obtained by press forming.

[0076] The first L-shaped cross-section member 81 includes a wall frame portion 83 standing upright from the bottom plate 12 , and a ceiling frame portion 84 formed integrally with this wall frame portion 83 and extending horizontally from the upper end of the wall frame portion 83 .

[0077] [tongue piece] FIG. 9(a) is an enlarged view of portion 9a in FIG. As shown in FIG. 9(a), the ceiling frame portion 84 is integrally formed with a tongue piece 85 extending toward the side frame 20 side.

[0078] 9(b), the tongue 85 extends beyond the arc portion 32 to the ceiling portion 33. The horizontal ceiling portion 33 and the tongue 85 can be joined together by a deposited metal 86 (or a screw). When the arcuate portion 32 is formed by roll forming, if the radius of curvature R is too small, cracks will occur in the arcuate portion 32. Therefore, the forming is carried out carefully. On the other hand, if the radius of curvature R is large, this need not be a concern and molding becomes easier. Providing the tongue piece 85 has the advantage that the radius of curvature R can be made large.

[0079] As described above, in one embodiment of the present invention, the inner closed cross-sectional portion 24 includes an inner wall portion 31 extending upward from the L-shaped cross-sectional portion 23, an arc portion 32 connected to the upper end of the inner wall portion 31, and a ceiling portion 33 extending outward from the tip of the arc portion 32, and the front frame 40 and the rear frame 80 are press-molded pressed products and include at least a wall frame portion 83 standing up from the bottom plate 12 and a ceiling frame portion 84 extending horizontally from the upper end of the wall frame portion 83, and a tongue piece 85 is integrally formed with the ceiling frame portion 84, which extends beyond the arc portion 32 to the ceiling portion 33 and is placed on and joined to the ceiling portion 33.

[0080] 5(a), the cooling plate 70 is disposed between the front and rear cross members 42. From the viewpoint of cooling the bottom plate 12 over a wide area, it is desirable to also dispose cooling plates in front of the foremost cross member 42 and behind the rearmost cross member 42. Therefore, in addition to the cooling plate 70, a front cooling plate 77 and a rear cooling plate 78 are provided as shown in FIG. 5(a).

[0081] [Rear cooling plate] As shown in FIG. 8( a ), a rear cooling plate 78 is disposed between the rearmost reinforcement member 60 and the rear frame 80 . To this end, as shown in FIG. 8(b), a flange connection portion 87 that connects the rear edge portion (specifically, the flange 74) of the rear cooling plate 78 is provided on the rear frame 80 (specifically, the second L-shaped cross-section member 82).

[0082] It is recommended that the joining be done by laser beam welding. Compared to other welding methods, laser beam welding has the following advantages: The beam diameter can be made smaller, narrowing the heat-affected zone. The cooling plate is thin to improve thermal efficiency, but it is possible to obtain strong bonding without drilling holes and to maintain the product shape well. It is preferable that the welding in other portions be laser beam welding.

[0083] This allows a rear cooling plate 78 to be placed behind the rearmost stiffener 60. Similarly, a front cooling plate (FIG. 5(a), reference numeral 77) can be placed in front of the frontmost stiffener. In addition, the front cooling plate 77 and the rear cooling plate 78 can be securely supported by welding, such as laser beam welding, without drilling holes.

[0084] [Bottom of outer closed section] 7(a), the bottom surface 26 of the outer closed cross-sectional portion 25 is disposed at a position lower than the lower surface of the cooling plate 70. The level of the bottom surface 26 of the outer closed cross-sectional portion 25 is defined as level Lv1.

[0085] [Bottom of outer closed section] As shown in Fig. 8(a), the rear frame 80 has a lower surface protrusion 88 that protrudes downward, and as shown in Fig. 8(b), the level of the lower surface of the lower surface protrusion 88 is set to level Lv2. This level Lv2 is aligned with the level Lv1 (Fig. 7(a)) of the bottom surface 26 of the outer closed cross-sectional portion 25. The cooling plate 70 is further provided with a protective plate 16, which is connected to the lower surface protrusion 88 by screws 92 via a sealant 91 as shown in Fig. 8(b). As shown in Fig. 8(c), the sealant 91 is applied so as to bypass the screws 92.

[0086] Similarly, as shown in FIG. 7(b), the sealant 91 is applied so as to go around the screw 92. As shown in FIG. 7( a ), the protective plate 16 is connected to the bottom surface 26 of the outer closed cross-sectional portion 25 by screws 92 via a sealant 91 .

[0087] The screw 92 may be of any type, but a flow drill screw (FDS) is preferable. With an FDS, a screw of a specific shape is pressed against stacked metal plates while rotating. Frictional heat caused by the rotation creates a hole in the plate. This hole takes the shape of a female screw. When the rotation is stopped, the metal plates cool and the fastening state is completed. Since it is not necessary to drill pilot holes in the metal plates, high workability is achieved.

[0088] In addition, in the above example, the sealing material 91 is applied to the protective plate 16, but the sealing material 91 may be applied to a mating member (such as the bottom surface 26) of the protective plate 16, and the protective plate 16 may be pressed against this sealing material 91. Therefore, the application position of the sealing material 91 is arbitrary and is not limited to the embodiment.

[0089] As shown in Figure 10(a) (comparative example), assuming that sealing material 91 is applied from the bottom surface 26 of the outer closed cross-sectional portion 25 of the side frame 20 to the underside protruding portion 88 of the rear frame 80, the sealing material 91 cannot be applied only to the recessed portion 27. As a countermeasure, in the comparative example, a temporary bridge 93 is placed. In this case, the cost of procuring the bridge 93 and the cost of installing it are incurred.

[0090] In Fig. 10(b) (embodiment), the bottom surface 44a of the rear fastening member 44, which is provided for a different purpose, is made to function as a bridge. This makes the temporary bridge 93 unnecessary, and eliminates the procurement and installation costs of the bridge 93.

[0091] [Rear fastening member] As shown in FIG. 10(a) (comparative example), the rear end of the side frame 20 is open and requires reinforcement. Therefore, as shown in Fig. 10(b) (embodiment), the rear end of the side frame 20 is closed with a rear fastening member 44. This member is a fastening member used when suspending the battery case 10 on the vehicle body. A rear fastener 44 is affixed to and welded to the rear end of the side frame 20 to reinforce the open end.

[0092] In addition, since the rear fastening member 44 is provided with a bottom surface 44a that also serves as a bridge, a temporary bridge (FIG. 10(a), reference numeral 93) is not required. As described above, the rear fastening member 44 of the present invention has three roles: fastening the battery case 10 to the vehicle body, reinforcing the side frame 20, and providing a surface for application of the sealant.

[0093] [Activation treatment of aluminum alloys] 11(a), a side frame 20 made of an aluminum alloy is prepared. Also, a bottom plate 12 to which an adhesive 95 is applied, and a protection plate 16 to which a sealant 91 is applied are prepared. As shown in FIG. 11(b), a plasma irradiator 96 (or a laser beam irradiator) is prepared.

[0094] The portion indicated by b in FIG. 11(a) is irradiated with plasma (or a laser beam) for a predetermined period of time by a plasma irradiator 96 (or a laser beam irradiator).

[0095] The surface of an aluminum alloy is covered with a strong oxide film. When the aluminum alloy is irradiated with plasma, the oxide film is destroyed and the surface is activated. This activation increases wettability. When the wettability is increased, in the case of the sealant 91, the sealant 91 spreads favorably, improving the sealing performance. In the case of the adhesive 95, the adhesive 95 adheres favorably to the aluminum alloy, strengthening the adhesive force. Moreover, long-term deterioration due to high wettability is suppressed.

[0096] After irradiation, the bottom plate 12 is attached to the L-shaped cross-sectional portion 23. Next, the protection plate 16 is pressed against the bottom surface 26 of the outer closed cross-sectional portion 25, and the two are joined together with the screws 92. As a result, the structure shown in FIG. 11(c) is obtained.

[0097] The side frame 20 and the bottom plate 12 are basically joined by welding, but by irradiating plasma (or laser beam), it is possible to replace this with adhesive 95. That is, the aluminum alloy surface is activated by plasma (or laser beam), so the adhesive performance of the adhesive 95 is significantly improved. Similarly, long-term deterioration due to high humidity is suppressed.

[0098] Furthermore, when the side frame and the protective plate 16 are joined with the screws 92, gaps inevitably occur between each screw 92 and adjacent screws 92, and water, sand, and other foreign matter can enter through these gaps. This intrusion is prevented by the sealant 91. When the surface of the aluminum alloy is activated, the sealing performance of the seal material 91 is expected to be improved. [Industrial Applicability]

[0099] The present invention is suitable for a battery case suspended in an electric vehicle. [Explanation of symbols]

[0100] 10...battery case, 11...battery, 12...bottom plate, 13...side wall, 14...upper cover, 16...protective plate, 20...side frame, 23...L-shaped cross-sectional portion, 24...inner closed cross-sectional portion, 24a, 24b...U-shaped bent portion, 25...outer closed cross-sectional portion, 25a...annular bent portion, 25b...shielding plate portion, 26...bottom surface of outer closed cross-sectional portion, 27...recess, 31...inner wall portion, 32...arc portion, 33...ceiling portion, 40...front frame, 42...cross member, 44...rear fastening member, 44a...rear bottom surface of fastening member, 50...connecting bracket, 51...vertex, 52...bottom side, 53...hypothetic side, 54...space, 55...storage recess, 60...reinforcement, 62...extension, 70...cooling plate, 75...piping, 77...front cooling plate, 78...rear cooling plate, 80...rear frame, 83...wall frame portion, 84...ceiling frame portion, 85...tongue, 87...flange connection portion, 88...bottom protrusion, 91...sealing material, 92...screw, 95...adhesive, Lv1, Lv2...level.

Claims

1. The invention according to claim 1 is a battery case comprising a bottom plate supporting a battery, side walls surrounding the battery placed on the bottom plate, and a top lid placed over the side walls to cover the battery, The bottom plate is a flat plate, The side walls have a rectangular frame structure in a plan view, the frame structure including left and right side frames, a front frame extending between front ends of the left and right side frames, and a rear frame extending between rear ends of the left and right side frames, The side frame includes, in a cross-sectional view, an L-shaped cross-sectional portion, and an inner closed cross-sectional portion and an outer closed cross-sectional portion that form a closed space, The L-shaped cross-sectional portions are arranged vertically on the bottom plate, The inner closed cross-sectional portion is disposed on the L-shaped cross-sectional portion, the outer closed cross-sectional portion is disposed outside the inner closed cross-sectional portion so as to be spaced apart from the bottom plate, and is disposed below the inner closed cross-sectional portion; a recess surrounded by the L-shaped cross-sectional portion, the inner closed cross-sectional portion, and the outer closed cross-sectional portion and having an open bottom, The battery case is characterized in that the side frame having such a structure is formed from a single metal plate.

2. The battery case according to claim 1, A cross member extending from the left side frame to the right side frame is further provided, and a connecting bracket is further provided to connect the cross member to the left and right side frames, the connecting bracket is triangular in plan view having a vertex, and includes a base portion that abuts against the left and right side frames, and a pair of oblique sides that extend from both ends of the base portion to the vertex, and includes a storage recess at the vertex for storing the ends of the left and right side frames; The battery case is characterized by having a space surrounded by this storage recess, the pair of oblique sides, and the bottom side.

3. The battery case according to claim 2, The bottom plate has a reinforcing material on the lower surface thereof, The reinforcing member is disposed at a position where the bottom plate is sandwiched between the reinforcing member and the cross member, The end of the reinforcing member is an extension that protrudes from the bottom plate, The battery case is characterized in that the extension portion extends to the middle of the recess so as to face the outer closed cross-sectional portion.

4. The battery case according to claim 2, The battery case is characterized in that the cross members consist of multiple members, a cooling plate is arranged between the front and rear cross members, and piping for supplying and discharging refrigerant to the cooling plate is arranged in the recess.

5. The battery case according to claim 1, the side frame is a roll product formed by roll forming, and the inner closed cross-sectional portion includes an inner wall portion extending upward from the L-shaped cross-sectional portion, an arc portion connected to an upper end of the inner wall portion, and a ceiling portion extending outward from a tip of the arc portion, the front frame and the rear frame are press-formed products, and include at least a wall frame portion standing upright from the bottom plate and a ceiling frame portion extending horizontally from an upper end of the wall frame portion; The battery case is characterized in that the ceiling frame portion is integrally formed with a tongue that extends beyond the arc portion to the ceiling portion and is coupled to the ceiling portion.

6. The battery case according to claim 4, In addition to the cooling plate, the battery case includes a front cooling plate and a rear cooling plate, the front frame has a flange connection portion to which a front edge portion of the front cooling plate can be welded; The battery case according to claim 1, wherein the rear frame has a flange connection portion to which a rear edge portion of the rear cooling plate can be welded.

7. The battery case according to claim 4, a bottom surface of the outer closed cross-sectional portion is disposed at a lower position than a lower surface of the cooling plate; the front frame and the rear frame each have a lower surface protrusion that protrudes downward, and the lower surface protrusion is aligned at the same level as a bottom surface of the outer closed cross-sectional portion; The battery case further includes a protective plate for protecting the cooling plate, The battery case is characterized in that the protective plate is detachably connected to the bottom surface of the outer closed cross-sectional portion and the lower surface protrusion with a screw via a sealing material.

8. The battery case according to claim 7, The side frame has a rear end closed by a rear fastening member.

9. The battery case according to claim 8, The battery case comprises a rear fastening member having a bottom surface to which the sealing material is applied, the bottom surface crossing the recess in a bottom view.

10. The battery case according to claim 7, A battery case characterized in that the side frame is made of an aluminum alloy, and the bottom surface of the outer closed cross-sectional portion is subjected to plasma treatment or laser treatment before coming into contact with the sealing material.

11. The battery case according to claim 1, The side frame is made of an aluminum alloy and is bonded to the bottom plate by an adhesive. A battery case characterized in that the L-shaped cross-sectional portion of the side frame is subjected to plasma treatment or laser treatment before coming into contact with the adhesive.

12. The battery case according to claim 1, The side frame is a battery case characterized in that an outer closed cross-sectional portion is formed by bending a single metal plate into an annular shape, and an inner closed side portion is formed by a U-shaped bent portion and a shielding plate portion that covers the opening.

Images