Battery unit

Abstract

A battery unit (100) is provided with a battery tray (10), cooling members (20), and reinforcing members (30). Each of the cooling members (20) includes a top plate (21) facing a bottom plate (11) outside the battery tray (10), and a flange (22) joined to the bottom plate (11). The reinforcing members (30) are overlaid on and joined to the cooling members (20) on both sides in the longitudinal direction of the cooling members (20). Each of the cooling members (20) includes ridge portions (241, 242, 243, 244). Each of the reinforcing members (30) includes ridge portions (31, 32, 33, 34) formed so as to be respectively continuous with the ridge portions (241, 242, 243, 244). Each of the ridge portions (31, 32, 33, 34) extends in the longitudinal direction of the cooling members (20) to the outside of the battery tray (10).

Description

Battery unit

[0001] The present disclosure relates to a battery unit.

[0002] For example, electric vehicles are equipped with a battery unit including a plurality of battery cells, and large-capacity battery units are used in electric vehicles to ensure a sufficient distance (cruising range) that can be traveled solely on electricity.

[0003] A battery unit requires a cooling function for the battery cells to operate stably at an appropriate temperature. For example, Patent Document 1 discloses a battery unit including a battery pack and a cooling member. The battery pack includes battery cells and a housing (battery tray). The cooling member is provided on the outside of a bottom plate of the battery tray. The cooling member includes a coolant flow path facing the bottom plate of the battery tray. In Patent Document 1, the coolant flow path is formed of an aluminum-based plated steel plate to ensure corrosion resistance against the coolant.

[0004] Patent Document 2 also discloses a battery unit having a cooling member on the outside of the bottom plate of the battery tray. In Patent Document 2, the cooling member includes a coolant flow path facing the bottom plate of the battery tray, similar to Patent Document 1. In Patent Document 2, the coolant flow path is formed of a zinc-based plated steel sheet to ensure corrosion resistance against the coolant. An inorganic coating or a resin coating is formed on the surface of the zinc-based plated steel sheet as a chemical conversion coating.

[0005] International Publication No. WO 2022 / 185840 International Publication No. WO 2022 / 185849

[0006] For example, when a battery unit is installed in an electric vehicle or the like, the battery unit is also required to have the function of protecting the battery cells in the event of a collision (crashworthiness). However, in a typical battery unit, the components for ensuring crashworthiness are provided separately from the cooling components. For example, a framework for ensuring crashworthiness is provided inside the battery tray, separate from the cooling components provided on the bottom plate of the battery tray. This can result in an increase in the number of parts in the battery unit and a complex structure.

[0007] An object of the present disclosure is to provide a battery unit that can impart collision resistance to a cooling member provided on a bottom plate of a battery tray.

[0008] A battery unit according to the present disclosure includes a battery tray, a cooling member, and a reinforcing member. The battery tray accommodates battery cells. The cooling member includes a top plate, a flange, a peripheral wall, an inlet, and an outlet. The top plate is disposed outside the battery tray so as to face the bottom plate of the battery tray. The flange is disposed on the outer periphery of the top plate and is joined to the bottom plate. The peripheral wall connects the top plate to the flange along its entire periphery. The peripheral wall, together with the battery tray and the top plate, forms a space to which a coolant is supplied. The inlet is used to introduce the coolant into the space. The outlet is used to discharge the coolant from the space. The cooling member is formed of a metal plate. The reinforcing members are overlapped and joined to the cooling member on both longitudinal sides of the cooling member. Each of the reinforcing members is formed of a metal plate. The cooling member further includes a first ridge portion, a second ridge portion, a third ridge portion, and a fourth ridge portion. The first ridge portion is interposed between the top plate and the peripheral wall and extends in the longitudinal direction of the cooling member. The second ridge portion is interposed between the top plate and the peripheral wall on the opposite side of the top plate from the first ridge portion and extends in the longitudinal direction of the cooling member. The third ridge portion is interposed between the peripheral wall and the flange on the opposite side of the peripheral wall from the first ridge portion and extends in the longitudinal direction of the cooling member. The fourth ridge portion is interposed between the peripheral wall and the flange on the opposite side of the peripheral wall from the second ridge portion and extends in the longitudinal direction of the cooling member. Each of the reinforcing members includes four fifth ridge portions. The fifth ridge portions are formed so as to be continuous with each of the first ridge portion, second ridge portion, third ridge portion, and fourth ridge portion. Each of the fifth ridge portions extends in the longitudinal direction of the cooling member to the outside of the battery tray.

[0009] According to the battery unit according to the present disclosure, it is possible to impart collision resistance to the cooling member provided on the bottom plate of the battery tray.

[0010] Fig. 1 is a perspective view of a battery unit according to an embodiment. Fig. 2 is another perspective view of the battery unit according to an embodiment. Fig. 3 is a plan view of a cooling member included in the battery unit shown in Figs. 1 and 2. Fig. 4 is a cross-sectional view showing a portion of the battery unit shown in Figs. 1 and 2.

[0011] A battery unit according to an embodiment includes a battery tray, a cooling member, and a reinforcing member. The battery tray accommodates battery cells. The cooling member includes a top plate, a flange, a peripheral wall, an inlet, and an outlet. The top plate is disposed outside the battery tray so as to face the bottom plate of the battery tray. The flange is disposed on the outer periphery of the top plate and is joined to the bottom plate. The peripheral wall connects the top plate to the flange along its entire periphery. The peripheral wall, together with the battery tray and the top plate, forms a space to which a coolant is supplied. The inlet is used to introduce the coolant into the space. The outlet is used to discharge the coolant from the space. The cooling member is formed of a metal plate. The reinforcing members are overlapped and joined to the cooling member on both longitudinal sides of the cooling member. Each of the reinforcing members is formed of a metal plate. The cooling member further includes a first ridge portion, a second ridge portion, a third ridge portion, and a fourth ridge portion. The first ridge portion is interposed between the top plate and the peripheral wall and extends in the longitudinal direction of the cooling member. The second ridge portion is interposed between the top plate and the peripheral wall on the opposite side of the top plate from the first ridge portion and extends in the longitudinal direction of the cooling member. The third ridge portion is interposed between the peripheral wall and the flange on the opposite side of the peripheral wall from the first ridge portion and extends in the longitudinal direction of the cooling member. The fourth ridge portion is interposed between the peripheral wall and the flange on the opposite side of the peripheral wall from the second ridge portion and extends in the longitudinal direction of the cooling member. Each of the reinforcing members includes four fifth ridge portions. The fifth ridge portions are formed so as to be continuous with each of the first ridge portion, second ridge portion, third ridge portion, and fourth ridge portion. Each of the fifth ridge portions extends in the longitudinal direction of the cooling member to the outside of the battery tray (first configuration).

[0012] In the battery unit according to the first configuration, a cooling member is joined to the bottom plate of the battery tray from the outside of the battery tray, and a space is formed between the battery tray and the cooling member. By supplying coolant into this space through an inlet of the cooling member, the battery cells in the battery tray can be cooled.

[0013] The battery unit according to the first configuration includes a battery tray, a cooling member, and a reinforcing member. The reinforcing members are overlapped on both longitudinal sides of the cooling member and joined to the cooling member. Each reinforcing member has a fifth ridge portion formed so as to be continuous with the first to fourth ridge portions of the cooling member. The fifth ridge portion extends in the longitudinal direction of the cooling member from the first to fourth ridge portions of the cooling member to the outside of the battery tray. In other words, the first to fourth ridge portions of the cooling member are extended to the outside of the battery tray by the fifth ridge portions of each reinforcing member. As a result, when a collision load is input to the battery unit from the longitudinal direction of the cooling member, the collision load is supported by the first to fourth ridge portions of the cooling member and the fifth ridge portions of each reinforcing member. This suppresses deformation of the cooling member, reducing the risk of damage to the battery cells in the battery tray. In this way, the battery unit according to the first configuration can impart collision resistance to the cooling member provided on the bottom plate of the battery tray.

[0014] In the battery unit according to the first configuration, the top plate may include a first bead. The first bead extends in the longitudinal direction of the cooling member. In this case, the reinforcing member may further include a second bead. The second bead is formed so as to be continuous with the first bead and extends in the longitudinal direction of the cooling member (second configuration).

[0015] In the second configuration, a first bead is formed on the top plate of the cooling member, and a second bead is formed on the reinforcing member. The second bead of the reinforcing member extends from the first bead of the cooling member in the longitudinal direction of the cooling member. In this case, when a collision load is applied to the battery unit from the longitudinal direction of the cooling member, the collision load can be supported not only by the ridges of the cooling member and both reinforcing members, but also by the beads of the cooling member and reinforcing members. This makes it less likely that the cooling member will deform.

[0016] In the second configuration, a first bead is formed on the top plate of the cooling member, which reduces the cross-sectional area of ​​the space for the coolant and increases the flow rate of the coolant within the space, thereby making it easier to cool the battery cells in the battery tray.

[0017] In the battery unit according to the first or second configuration, the cooling member may be formed of an aluminum-based plated steel plate (third configuration).

[0018] A coolant is supplied to the space formed by the cooling member. Therefore, it is preferable that the cooling member has corrosion resistance against the coolant. Therefore, in the third configuration, the cooling member is formed of an aluminum-based plated steel plate. This allows the cooling member to have high corrosion resistance against the coolant.

[0019] In the battery unit according to the first or second configuration, the cooling member may be formed of a zinc-based plated steel sheet. In this case, it is preferable that a chemical conversion coating is formed on the surface of the zinc-based plated steel sheet (fourth configuration).

[0020] In the fourth configuration, the cooling member is formed of a zinc-based plated steel sheet having a chemical conversion coating on its surface, thereby providing the cooling member with high corrosion resistance against the coolant.

[0021] In the battery unit according to any one of the first to fourth configurations, the cooling member can have a Vickers hardness of 130 HV or more (fifth configuration).

[0022] In the fifth configuration, the cooling member has a Vickers hardness of 130 HV or more, which allows the cooling member to have high crash resistance.

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In these drawings, the same or equivalent components are designated by the same reference numerals, and the same description will not be repeated.

[0024] [Structure of Battery Unit] Fig. 1 is a perspective view of a battery unit 100 according to this embodiment. Fig. 2 is a perspective view of the battery unit 100 as seen from a different direction than Fig. 1. The battery unit 100 is mounted on, for example, an electric vehicle.

[0025] 1 and 2, a battery unit 100 includes a battery tray 10, a plurality of cooling members 20, and a plurality of reinforcing members 30.

[0026] Referring to Fig. 1, the battery tray 10 has an overall concave shape. The battery tray 10 includes a bottom plate 11 and a peripheral wall 12. The bottom plate 11 has, for example, a rectangular shape in a plan view of the battery tray 10. The peripheral wall 12 is provided continuous with the periphery of the bottom plate 11. The peripheral wall 12 has an opening on the side opposite the bottom plate 11. Although not shown, a cover may be attached to the opening in the peripheral wall 12.

[0027] The battery tray 10 accommodates a plurality of battery cells 40. In this embodiment, a plurality of battery modules 50 are accommodated in the battery tray 10. Each battery module 50 includes two or more modularized battery cells 40. However, in the battery unit 100, the battery cells 40 do not have to be modularized. Each battery cell 40 is, for example, a lithium-ion battery cell. Each battery cell 40 may be a prismatic cell, a cylindrical cell, or a pouch-shaped cell.

[0028] In the example of Fig. 1, the battery modules 50 are attached to the bottom plate 11 of the battery tray 10 via a plurality of attachment members 60. The attachment members 60 are each elongated and arranged in parallel within the battery tray 10. The battery modules 50 are arranged along the longitudinal direction of the attachment members 60. The battery modules 50 may be fastened to the attachment members 60 by a known fastening method. The attachment members 60 may be joined to the bottom plate 11 of the battery tray 10 by, for example, spot welding.

[0029] Referring to Fig. 2, a plurality of cooling members 20 are arranged outside the battery tray 10. The cooling members 20 are attached to the bottom plate 11 of the battery tray 10 on the opposite side of the battery module 50 (Fig. 1). The cooling members 20 are each elongated and arranged in parallel. When the battery unit 100 is mounted on an electric vehicle, the cooling members 20 may each extend in the left-right direction of the vehicle body. Both longitudinal ends of the cooling members 20 protrude outside the bottom plate 11 of the battery tray 10. Each cooling member 20 is formed from a metal plate.

[0030] Each of the cooling members 20 includes a top plate 21 , a flange 22 , a peripheral wall 23 , and ridge portions 241 , 242 , 243 , and 244 .

[0031] 3 is a plan view of the cooling member 20. Referring to FIGS. 2 and 3, the top plate 21 extends in the longitudinal direction of the cooling member 20. In this embodiment, the top plate 21 has a substantially rectangular shape in a plan view of the cooling member 20. However, the top plate 21 may have other shapes, such as an oval track shape, in a plan view of the cooling member 20. When the battery unit 100 is viewed from the cooling member 20 side, the top plate 21 is disposed within the range of the bottom plate 11 of the battery tray 10.

[0032] In this embodiment, the top plate 21 includes at least one bead 211. The bead 211 extends in the longitudinal direction of the cooling member 20. The bead 211 has, for example, a concave shape on the inside of the cooling member 20. The bead 211 may also have a convex shape on the outside of the cooling member 20. In this embodiment, a plurality of beads 211 are provided on the top plate 21.

[0033] The flange 22 is disposed on the outer periphery of the top plate 21. That is, the flange 22 is disposed so as to surround the top plate 21 in a plan view of the cooling member 20. The flange 22 forms the outer periphery of the cooling member 20. The peripheral wall 23 connects the top plate 21 to the flange 22 around the entire periphery.

[0034] The ridge portion 241 is interposed between the top plate 21 and the peripheral wall 23. The ridge portion 242 is interposed between the top plate 21 and the peripheral wall 23 on the opposite side of the top plate 21 from the ridge portion 241. The ridge portions 241 and 242 are each provided adjacent to the top plate 21 and connect the top plate 21 to the peripheral wall 23. The ridge portions 241 and 242 are both corner portions between the top plate 21 and the peripheral wall 23. The ridge portions 241 and 242 each extend in the longitudinal direction of the cooling member 20.

[0035] Ridge line portion 243 is located between peripheral wall 23 and flange 22, on the opposite side of peripheral wall 23 to ridge line portion 241. Ridge line portion 244 is located between peripheral wall 23 and flange 22, on the opposite side of peripheral wall 23 to ridge line portion 242. Ridge line portions 243 and 244 are each provided adjacent to peripheral wall 23 and connect peripheral wall 23 to flange 22. Both ridge line portions 243 and 244 are corner portions between peripheral wall 23 and flange 22. Ridge line portions 243 and 244 each extend in the longitudinal direction of cooling member 20. When cooling member 20 is incorporated in an electric vehicle, ridge line portions 241, 242, 243, and 244 can extend substantially in the left-right direction of the vehicle body.

[0036] The cooling member 20 further includes ridge portions 245, 246, 247, and 248. When the cooling member 20 is installed in an electric vehicle, the ridge portions 245, 246, 247, and 248 extend substantially in the front-to-rear direction of the vehicle body. The ridge portion 245 connects the ridge portions 241 and 242 at one end of the cooling member 20 in the longitudinal direction. The ridge portion 246 connects the ridge portions 241 and 242 at the other end of the cooling member 20 in the longitudinal direction. The ridge portions 245 and 246 are each interposed between the top plate 21 and the peripheral wall 23. Like the ridge portions 241 and 242, the ridge portions 245 and 246 are corner portions between the top plate 21 and the peripheral wall 23.

[0037] Ridge line portion 247 connects ridge line portions 243 and 244 at one longitudinal end of cooling member 20. Ridge line portion 248 connects ridge line portions 243 and 244 at the other longitudinal end of cooling member 20. Ridge line portions 247 and 248 are each interposed between peripheral wall 23 and flange 22. Like ridge line portions 243 and 244, ridge line portions 247 and 248 are corner portions between peripheral wall 23 and flange 22.

[0038] Each cooling member 20 further includes an inlet 25 and an outlet 26 for the coolant. The inlet 25 is a hole for introducing the coolant into the cooling member 20. The outlet 26 is a hole for discharging the coolant from the cooling member 20. As the coolant, for example, a long life coolant (LLC) aqueous solution containing an organic component is used.

[0039] In this embodiment, the inlet 25 and the outlet 26 are formed in the top plate 21. The inlet 25 and the outlet 26 penetrate the top plate 21 in the plate thickness direction. The inlet 25 is formed at one end of the top plate 21 in the longitudinal direction of the cooling member 20. The outlet 26 is formed at the other end of the top plate 21 in the longitudinal direction of the cooling member 20. However, the positions of the inlet 25 and the outlet 26 are not limited to the example of this embodiment.

[0040] As shown in Fig. 2 , the reinforcing members 30 are overlapped and joined to at least one cooling member 20 on both longitudinal sides of the cooling member 20. The reinforcing members 30 cover a portion of each of the flanges 22 and the top plate 21 on both longitudinal sides of the cooling member 20. Each of the reinforcing members 30 is overlapped with the cooling member 20 from the side opposite the battery tray 10. However, for ease of explanation, Fig. 2 shows one of the reinforcing members 30 separated from the cooling member 20. When the battery unit 100 is mounted on an electric vehicle, the reinforcing members 30 are fastened to the vehicle body together with both longitudinal ends of the cooling member 20 via, for example, brackets (not shown) or the like.

[0041] In this embodiment, each of the reinforcing members 30 is overlapped across the plurality of cooling members 20. More specifically, one reinforcing member 30 extends from one longitudinal end of the plurality of cooling members 20 arranged in parallel so as to intersect with these cooling members 20. Furthermore, another reinforcing member 30 extends from the other longitudinal end of the plurality of cooling members 20 arranged in parallel so as to intersect with these cooling members 20. When the battery unit 100 is mounted on an electric vehicle, the reinforcing member 30 extends, for example, in the front-to-rear direction of the vehicle body. However, the reinforcing member 30 may be divided into a plurality of pieces corresponding to each of the cooling members 20. Each reinforcing member 30 is formed of a metal plate.

[0042] Each of the reinforcing members 30 includes ridge portions 31, 32, 33, and 34. In the reinforcing member 30, the ridge portions 31, 32, 33, and 34 are provided for each cooling member 20. The ridge portions 31, 32, 33, and 34 are formed on the reinforcing member 30 so as to be continuous with the ridge portions 241, 242, 243, and 244 of the cooling member 20, respectively. The ridge portions 31, 32, 33, and 34 are portions that form corner portions between flat portions in the reinforcing member 30, respectively.

[0043] The ridge portions 31 and 32 extend in the longitudinal direction of the cooling member 20 so as to extend the ridge portions 241 and 242 on the top plate 21 side of the cooling member 20, respectively. The ridge portions 33 and 34 extend in the longitudinal direction of the cooling member 20 so as to extend the ridge portions 243 and 244 on the flange 22 side of the cooling member 20, respectively. The ridge portions 31, 32, 33 and 34 extend in the longitudinal direction of the cooling member 20 from the ridge portions 241, 242, 243 and 244 of the cooling member 20 to the outside of the battery tray 10. The ridge portions 31, 32, 33 and 34 may extend to the edge of the reinforcing member 30 in the longitudinal direction of the cooling member 20.

[0044] In this embodiment, each of the reinforcing members 30 further includes at least one bead 35. In this embodiment, a plurality of beads 35 are provided on the reinforcing member 30 corresponding to the plurality of beads 211 of the cooling member 20. Each of the beads 35 is formed on the reinforcing member 30 so as to be continuous with the bead 211 of the cooling member 20. The bead 35 extends in the longitudinal direction of the cooling member 20 so as to extend the bead 211 of the cooling member 20. It is preferable that the bead 35 extend to the outside of the battery tray 10 in the longitudinal direction of the cooling member 20.

[0045] In this embodiment, one reinforcing member 30 is provided so as to cover the inlet 25 of each cooling member 20. In this case, this reinforcing member 30 is provided with an inlet (not shown) for the coolant at a position corresponding to the inlet 25 of the cooling member 20. The other reinforcing member 30 is provided so as to cover the outlet 26 ( FIG. 3 ) of each cooling member 20. In this case, this reinforcing member 30 is provided with an outlet (not shown) for the coolant at a position corresponding to the outlet 26 of the cooling member 20. However, when the inlet 25 and the outlet 26 are formed in a portion of each cooling member 20 that is not covered by the reinforcing member 30, it is not necessary to provide the inlet and the outlet in the reinforcing member 30.

[0046] 4 is a diagram (cross-sectional view) of the battery unit 100 cut along a plane perpendicular to the longitudinal direction of the cooling member 20. In FIG. 4, one cooling member 20 and a reinforcing member 30 joined to this cooling member 20 are shown.

[0047] As shown in Fig. 4, the cooling member 20 has a generally hat-shaped cross section. Specifically, the generally hat-shaped cross section is formed by a top plate 21, a flange 22, and a peripheral wall 23. The top plate 21 is disposed to face the bottom plate 11 of the battery tray 10. The top plate 21 faces the bottom plate 11 with a gap therebetween. The flange 22 is joined to the bottom plate 11 of the battery tray 10 in a liquid-tight manner. Therefore, the battery tray 10 and the top plate 21 and peripheral wall 23 of the cooling member 20 form a space 27 to which the coolant is supplied.

[0048] A sealer 70 may be used to join the battery tray 10 and the cooling member 20. The sealer 70 is, for example, a coating agent whose main component is resin. As the sealer 70, a known sealer for ensuring liquid-tightness may be used.

[0049] The bottom plate 11 of the battery tray 10 and the flange 22 of the cooling member 20 may be joined using the sealer 70 in combination with spot welding or mechanical joining. Examples of mechanical joining include joining the bottom plate 11 of the battery tray 10 and the flange 22 of the cooling member 20 by partial crimping, joining using rivets, etc. Alternatively, the bottom plate 11 of the battery tray 10 and the flange 22 of the cooling member 20 may be joined by continuous welding such as laser welding or seam welding, brazing, or friction diffusion welding. The bottom plate 11 of the battery tray 10 and the flange 22 of the cooling member 20 may also be joined by an adhesive. If the sealer 70 functions as an adhesive, the bottom plate 11 of the battery tray 10 and the flange 22 of the cooling member 20 can also be joined by the sealer 70 alone.

[0050] As shown in Fig. 4, a reinforcing member 30 is joined to the cooling member 20. In a cross section of the battery unit 100, the reinforcing member 30 has a shape that follows the top plate 21, peripheral wall 23, and flange 22 of the cooling member 20. The reinforcing member 30 is joined to the top plate 21 and flange 22 by, for example, spot welding. In this case, the top plate 21 includes a flat portion for spot welding.

[0051] The ridge portions 241, 242 of the cooling member 20 are each corner portions that directly connect the flat portion of the top plate 21 and the peripheral wall 23. In a cross-sectional view of the battery unit 100, the ridge portions 241, 242 each have a curved shape that convexly extends outward from the cooling member 20. The ridge portions 241, 242 may also have an arc shape in a cross-sectional view of the battery unit 100. The radius of curvature (inside of the bend) of the ridge portions 241, 242 of the cooling member 20 is, for example, 15 mm or less. The radius of curvature (inside of the bend) of the ridge portions 241, 242 may be 2 mm or more.

[0052] In a cross section of the battery unit 100 at a portion where the reinforcing member 30 is joined to the top plate 21 and flange 22 of the cooling member 20, the ridges 31 and 32 of the reinforcing member 30 overlap the ridges 241 and 242 of the cooling member 20, respectively. In a cross-sectional view of the battery unit 100, the ridges 31 and 32 each have a convex curved shape along the ridges 241 and 242 of the cooling member 20. Because the reinforcing member 30 overlaps the cooling member 20 from the outside, the radius of curvature of the inner sides of the ridges 31 and 32 is slightly larger than the radius of curvature of the inner sides of the ridges 241 and 242 of the cooling member 20. The radius of curvature (inside of the bend) of the ridges 31 and 32 is, for example, 15 mm or less. The radius of curvature (inside of the bend) of the ridges 31 and 32 may be 3 mm or more.

[0053] The ridge portions 243, 244 of the cooling member 20 are corner portions that directly connect the peripheral wall 23 and the flange 22. In a cross-sectional view of the battery unit 100, the ridge portions 243, 244 each have a concave curved shape on the inside of the cooling member 20. The ridge portions 243, 244 may also have an arc shape in a cross-sectional view of the battery unit 100. The radius of curvature (inside of the bend) of the ridge portions 243, 244 is, for example, 15 mm or less. The radius of curvature (inside of the bend) of the ridge portions 243, 244 may be 3 mm or more.

[0054] In a cross section of the battery unit 100 at a portion where the reinforcing member 30 is joined to the top plate 21 and flange 22 of the cooling member 20, the ridges 33 and 34 of the reinforcing member 30 overlap the ridges 243 and 244 of the cooling member 20, respectively. In a cross-sectional view of the battery unit 100, the ridges 33 and 34 each have a concave curved shape along the ridges 243 and 244 of the cooling member 20. Because the reinforcing member 30 overlaps the cooling member 20 from the outside, the radius of curvature of the inner bends of the ridges 33 and 34 is slightly smaller than the radius of curvature of the inner bends of the ridges 243 and 244 of the cooling member 20. The radius of curvature (inner bend) of the ridges 33 and 34 is, for example, 15 mm or less. The radius of curvature (inner bend) of the ridges 33 and 34 may be 2 mm or more.

[0055] In this embodiment, the top plate 21 of the cooling member 20 includes a plurality of beads 211. Each of the beads 211 preferably has at least one ridge portion 211a. Like the other ridge portions 241, 242, 243, and 244, the ridge portion 211a is a corner portion that connects flat portions together. In a cross-sectional view of the battery unit 100, the ridge portion 211a can have a curved shape that is convex on the outside of the cooling member 20 or concave on the inside of the cooling member 20. The ridge portion 211a extends in the longitudinal direction of the cooling member 20.

[0056] In a cross section of the battery unit 100 at a portion where the reinforcing member 30 is joined to the top plate 21 and flange 22 of the cooling member 20, the beads 35 of the reinforcing member 30 overlap the beads 211 of the cooling member 20. In a cross-sectional view of the battery unit 100, the beads 35 of the reinforcing member 30 have a shape that follows the shape of the beads 211 of the cooling member 20. When the beads 211 of the cooling member 20 have ridges 211a, the beads 35 also have ridges 351. The ridges 351 have a convex or concave curved shape corresponding to the ridges 211a of the beads 211 of the cooling member 20, and extend in the longitudinal direction of the cooling member 20. The ridges 351 can extend in the longitudinal direction of the cooling member 20 to the outside of the battery tray 10.

[0057] In this embodiment, the bottom plate 11 of the battery tray 10 has projections and recesses. This prevents the bottom plate 11 from being deflected by the weight of the battery modules 50 (FIG. 1). However, the bottom plate 11 may be flat throughout.

[0058] [Material of Battery Unit] The cooling member 20 and the reinforcing member 30 are typically formed of steel plate to ensure their strength. The cooling member 20 and the reinforcing member 30 can be formed, for example, by press-forming a steel plate. The cooling member 20 and the reinforcing member 30 have a thickness of, for example, 0.4 mm or more and 2.0 mm or less, and preferably 1.0 mm or more and 1.8 mm or less. The thickness of each reinforcing member 30 is preferably greater than the thickness of each cooling member 20. However, the thickness of each reinforcing member 30 may be equal to or less than the thickness of each cooling member 20.

[0059] From the viewpoint of ensuring corrosion resistance against the coolant, each of the cooling members 20 may be formed of an aluminum-based plated steel sheet. The aluminum-based plated steel sheet is a steel sheet including a base steel sheet and an aluminum (Al)-based plating layer formed on the base steel sheet.

[0060] The Al-based plating layer is a plating layer containing Al. The Al-based plating layer contains, for example, 70% or more Al by mass. The Al-based plating layer is preferably a two-component or multi-component plating layer containing, by mass, 70 to 98% Al and 2 to 15% Si. From the viewpoint of further improving the workability and corrosion resistance of the aluminum-based plated steel sheet, the Si content of the Al-based plating layer is more preferably 3 to 15% by mass. The Al-based plating layer is formed on at least the surface of the cooling member 20 that is located on the space 27 side. The Al-based plating layer may be formed on both surfaces of the cooling member 20.

[0061] The Al-based plating layer may contain trace amounts of Fe, Ni, Co, etc. as impurity elements. The Al-based plating layer may contain Mg, Sn, misch metal, Sb, Zn, Cr, W, V, Mo, etc. as necessary. Although not particularly limited, the Al-based plating layer may be, for example, hot-dip flux plating, hot-dip plating formed by the Sendzimir method or the all-radiant method, electroplating, vapor deposition plating, etc.

[0062] In order to further enhance the corrosion resistance of the aluminum-based plated steel sheet, a chemical conversion coating may be formed on the surface of the aluminum-based plated steel sheet. The chemical conversion coating is formed on at least the surface of the cooling member 20 that is located on the space 27 side. The chemical conversion coating may be formed on both surfaces of the cooling member 20.

[0063] The chemical conversion coating is a coating containing a Zr-based component, a Ti-based component, or a Si-based component as a main component. That is, the chemical conversion coating contains 50% or more by mass of the Zr-based component, the Ti-based component, or the Si-based component. The chemical conversion coating may also contain an organic component. As a chemical conversion coating to be applied to an aluminum-based plated steel sheet, for example, the one described in Patent Document 1 can be used. The chemical conversion coating can be formed, for example, by applying a Zr-based, Ti-based, or Si-based chemical conversion treatment solution (coating treatment solution) to the aluminum-based plated steel sheet by a known method, followed by baking and drying.

[0064] The cooling member 20 may be formed of a zinc-based plated steel sheet instead of an aluminum-based plated steel sheet. The zinc-based plated steel sheet is a steel sheet including a base steel sheet and a zinc (Zn)-based plating layer formed on the base steel sheet. The Zn-based plating layer is a plating layer containing Zn. The Zn-based plating layer is formed on at least the surface of the cooling member 20 that is located on the space 27 side. The Zn-based plating layer may be formed on both surfaces of the cooling member 20.

[0065] Examples of zinc-based plated steel sheets include zinc-plated steel sheets, zinc-nickel-plated steel sheets, zinc-iron-plated steel sheets, zinc-chromium-plated steel sheets, zinc-aluminum-plated steel sheets, zinc-titanium-plated steel sheets, zinc-magnesium-plated steel sheets, zinc-manganese-plated steel sheets, zinc-aluminum-magnesium-plated steel sheets, zinc-aluminum-magnesium-silicon-plated steel sheets, etc. In these plated steel sheets, the Zn-based plating layer may contain small amounts of different metal elements or impurity elements such as Co, Mo, W, Ni, Ti, Cr, Al, Mn, Fe, Mg, Pb, Bi, Sb, Sn, Cu, Cd, As, etc., and may also have inorganic substances such as silica, alumina, titania, etc. dispersed therein.

[0066] The Zn-based plating layer may be used in combination with other plating layers. That is, the zinc-based plated steel sheet may have a multi-layer plating that combines a Zn-based plating layer with a plating layer such as iron plating, iron-phosphorus plating, nickel plating, or cobalt plating. Methods for forming the Zn-based plating layer and other plating layers include, but are not limited to, electroplating, hot-dip plating, vapor deposition plating, dispersion plating, vacuum plating, and the like.

[0067] A chemical conversion coating is formed on the surface of the zinc-based plated steel sheet. The chemical conversion coating is formed on at least the surface of the cooling member 20 that is located on the space 27 side. The chemical conversion coating may be formed on both surfaces of the cooling member 20.

[0068] The chemical conversion coating is an inorganic coating or a resin coating. The inorganic coating is a coating containing a Si-based component or a Zr-based component as a main component. That is, the inorganic coating contains 50% or more by mass of the Si-based component or the Zr-based component. The inorganic coating may also contain an organic component. For example, the inorganic coating or resin coating described in Patent Document 2 can be used as the chemical conversion coating for zinc-based plated steel sheets.

[0069] Although not particularly limited, the chemical conversion coating can be formed by applying an inorganic or resin-based chemical conversion treatment solution (coating treatment solution) to a zinc-based plated steel sheet by a known method, followed by baking and drying. A preferred combination of a zinc-based plated steel sheet and a chemical conversion coating is, for example, a combination of a zinc-aluminum-magnesium plated steel sheet and an inorganic coating containing a Si-based component as a main component. Another preferred example of a combination is a combination of a zinc-aluminum plated steel sheet and a resin coating.

[0070] In the aluminum-based plated steel sheet and the zinc-based plated steel sheet, the material of the base steel sheet is not particularly limited, and may be, for example, IF steel containing Ti, Nb, B, or the like, Al-k steel, Cr-added steel, stainless steel, high-tensile steel, low-carbon steel, medium-carbon steel, high-carbon steel, alloy steel, or the like.

[0071] In the aluminum-based plated steel sheet and the zinc-based plated steel sheet, the material of the base steel sheet is not particularly limited, and may be, for example, IF steel containing Ti, Nb, B, or the like, Al-k steel, Cr-added steel, stainless steel, high-tensile steel, low-carbon steel, medium-carbon steel, high-carbon steel, alloy steel, or the like.

[0072] The reinforcing member 30 may be formed of an aluminum-based plated steel sheet or a zinc-based plated steel sheet, similar to the cooling member 20. When the reinforcing member 30 is formed of an aluminum-based plated steel sheet or a zinc-based plated steel sheet, the above-mentioned chemical conversion coating may be formed on the surface of the reinforcing member 30. However, the material of the reinforcing member 30 may be different from the material of the cooling member 20.

[0073] The cooling member 20 preferably has a Vickers hardness of 130 HV or more. The reinforcing member 30 can also have a Vickers hardness of 130 HV or more. The cooling member 20 and the reinforcing member 30 each preferably have a Vickers hardness of 170 HV or more, and even more preferably 230 HV or more. The Vickers hardness of the reinforcing member 30 may be greater than that of the cooling member 20. The Vickers hardness of the cooling member 20 is, for example, 500 HV or less. The Vickers hardness of the reinforcing member 30 is, for example, 500 HV or less. The Vickers hardness of the cooling member 20 and the reinforcing member 30 can be measured by a Vickers hardness test specified in JIS Z 2244-1:2020. Specifically, first, test pieces of a size suitable for the Vickers hardness test are obtained from any position of the cooling member 20 and the reinforcing member 30 by laser cutting or the like. Next, each test piece is embedded in resin so that the cross section of each of the cooling member 20 and the reinforcing member 30 is positioned on the surface, and the cross section is polished. Then, Vickers hardness is measured at an arbitrary position in the thickness direction of this cross section, for example, at the center in the thickness direction or near there, in accordance with JIS Z 2244-1:2020, with a test force of 300 gf (2.9 N).

[0074] The material of the battery tray 10 may be the same as or different from that of the cooling member 20 and / or the reinforcing member 30. The battery tray 10 may be formed of, for example, mild steel. The plate thickness of the battery tray 10 is usually smaller than that of the cooling member 20 and the reinforcing member 30. The plate thickness of the bottom plate 11 of the battery tray 10 is, for example, 0.4 mm or more and 1.2 mm or less, and preferably 0.5 mm or more and 1.0 mm or less.

[0075] [Effect] In the battery unit 100 according to this embodiment, a space 27 to which the coolant is supplied is formed by the bottom plate 11 of the battery tray 10 and the top plate 21 and peripheral wall 23 of each cooling member 20. The coolant is introduced into this space 27 from the inlet 25 and discharged from the outlet 26, thereby cooling the battery cells 40 in the battery tray 10.

[0076] In the battery unit 100 according to this embodiment, each cooling member 20 is reinforced by a reinforcing member 30. More specifically, the reinforcing members 30 are overlapped and joined to each cooling member 20 on both longitudinal sides of the cooling member 20. Each reinforcing member 30 has ridge portions 31, 32, 33, and 34 that are continuous with ridge portions 241, 242, 243, and 244 of the cooling member 20, respectively. That is, the ridge portions 241, 242, 243, and 244 of the cooling member 20 are extended to the outside of the battery tray 10 by the ridge portions 31, 32, 33, and 34 of the reinforcing member 30. As a result, when a collision load is input to the battery unit 100 from the longitudinal direction of the cooling member 20, the collision load is supported by the ridge portions 241, 242, 243, and 244 of the cooling member 20 and the ridge portions 31, 32, 33, and 34 of the reinforcing member 30. This suppresses deformation of the cooling member 20 and reduces the risk of damage to the battery cells 40 in the battery tray 10. In this way, the battery unit 100 according to this embodiment can impart collision resistance to the cooling member 20 provided on the bottom plate 11 of the battery tray 10.

[0077] Both longitudinal ends of the cooling member 20, i.e., the portions where the bottom plate 11 of the battery tray 10 and the flange 22 of the cooling member 20 overlap, are flat and have relatively low rigidity, and are therefore prone to deformation when subjected to a collision load. However, in this embodiment, both longitudinal ends of the cooling member 20 are covered by the reinforcing member 30, and the ridge portions 31, 32, 33, and 34 of the reinforcing member 30 are arranged so as to be continuous with the ridge portions 241, 242, 243, and 244 of the cooling member 20. Therefore, the collision load input from the longitudinal direction of the cooling member 20 is transmitted from the ridge portions 31, 32, 33, and 34 of the reinforcing member 30 to the ridge portions 241, 242, 243, and 244 of the cooling member 20 and supported by these ridge portions. As a result, deformation at both longitudinal ends of the cooling member 20 can be suppressed.

[0078] In this embodiment, at least one bead 211 is formed on the top plate 21 of each cooling member 20. Furthermore, a bead 35 is formed on each reinforcing member 30 corresponding to the bead 211 of the cooling member 20. The bead 211 of the cooling member 20 is extended, for example, to the outside of the battery tray 10 by the bead 35 of the reinforcing member 30. As a result, when a collision load is input to the battery unit 100, the collision load is also supported by the bead 211 of the cooling member 20 and the bead 35 of the reinforcing member 30. When the bead 211 of the cooling member 20 and the bead 35 of the reinforcing member 30 have ridge portions 211a, 351 as in this embodiment, the collision load is more easily supported. Therefore, the cooling member 20 can be provided with superior collision resistance.

[0079] By providing the bead 211 of the cooling member 20, the cross-sectional area of ​​the space 27 for the coolant is reduced, and the flow rate of the coolant in the space 27 can be increased. Therefore, the battery cells 40 in the battery tray 10 can be more easily cooled.

[0080] In the battery unit 100 according to this embodiment, each of the cooling members 20 is preferably formed of an aluminum-based plated steel plate. At least the surface of the cooling member 20 facing the space 27 is preferably provided with an Al-based plating layer over the entire surface. Similarly, the battery tray 10 is preferably formed of an aluminum-based plated steel plate. At least the surface of the battery tray 10 facing the space 27 is preferably provided with an Al-based plating layer over the entire surface. This makes it easier to suppress corrosion of the cooling member 20 and the battery tray 10 due to the coolant. Suppressing corrosion of the cooling member 20 and the battery tray 10 makes it less likely that the thermal conductivity of the cooling member 20 and the battery tray 10 will decrease, and that components of the cooling member 20 and the battery tray 10 will not leach into the coolant.

[0081] When the battery unit 100 is mounted on an electric vehicle, the battery unit 100 is disposed, for example, under the floor of the vehicle body, and the cooling member 20 is exposed to the external environment. Therefore, when the cooling member 20 is formed of an aluminum-based plated steel plate, it is more preferable that an Al-based plating layer be provided on both sides of the cooling member 20. This improves the corrosion resistance of the cooling member 20 against the external environment. Similarly, it is more preferable that an Al-based plating layer be provided on both sides of the battery tray 10.

[0082] In the battery unit 100 according to this embodiment, each of the cooling members 20 may be formed of a zinc-based plated steel sheet. The battery tray 10 may also be formed of a zinc-based plated steel sheet. In this case, a chemical conversion coating is preferably formed on the surface of the zinc-based plated steel sheet. At least the surface of the cooling member 20 facing the space 27 is preferably provided with a Zn-based plating layer over the entire surface, and this Zn-based plating layer is coated with a chemical conversion coating. Furthermore, at least the surface of the battery tray 10 facing the space 27 is preferably provided with a Zn-based plating layer over the entire surface, and this Zn-based plating layer is preferably coated with a chemical conversion coating. This more effectively suppresses corrosion of the cooling member 20 and the battery tray 10 due to the coolant. This reduces the thermal conductivity of the cooling member 20 and the battery tray 10 and the elution of components of the cooling member 20 and the battery tray 10 into the coolant.

[0083] When the cooling member 20 is formed of a zinc-based plated steel sheet, from the viewpoint of improving corrosion resistance against the external environment, it is more preferable that the zinc-based plating layer and the chemical conversion coating be provided on both sides of the cooling member 20. It is also more preferable that the zinc-based plating layer and the chemical conversion coating be provided on both sides of the battery tray 10.

[0084] In the battery unit 100 according to this embodiment, the cooling member 20 preferably has a Vickers hardness of 130 HV or more, which further improves the collision resistance of the cooling member 20. Furthermore, if the reinforcing member 30 also has a Vickers hardness of 130 HV or more, it is possible to impart even better collision resistance to the cooling member 20.

[0085] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0086] 100: Battery unit 10: Battery tray 11: Bottom plate 20: Cooling member 21: Top plate 211: Bead 22: Flange 23: Peripheral wall 241: (First) Ridge line portion 242: (Second) Ridge line portion 243: (Third) Ridge line portion 244: (Fourth) Ridge line portion 25: Inlet port 26: Outlet port 27: Space 30: Reinforcing member 31, 32, 33, 34: (Fifth) Ridge line portion 35: Bead 40: Battery cell

Claims

1. A battery unit comprising: a battery tray in which battery cells are accommodated; a top plate arranged outside the battery tray so as to face a bottom plate of the battery tray; a flange arranged on the outer periphery of the top plate and joined to the bottom plate; a peripheral wall connecting the top plate to the flange around the entire periphery and forming, together with the battery tray and the top plate, a space to which a coolant is supplied, and including an inlet for introducing the coolant into the space and an outlet for discharging the coolant from the space; and a cooling member made of a metal plate; and reinforcing members, each made of a metal plate, overlapping and joined to the cooling member on both longitudinal sides of the cooling member, wherein the cooling member further comprises: a first ridge portion interposed between the top plate and the peripheral wall and extending in the longitudinal direction; and a second ridge portion interposed between the top plate and the peripheral wall on the opposite side of the top plate from the first ridge portion and extending in the longitudinal direction. a third ridge portion interposed between the peripheral wall and the flange on the opposite side of the peripheral wall from the first ridge portion and extending in the longitudinal direction; and a fourth ridge portion interposed between the peripheral wall and the flange on the opposite side of the peripheral wall from the second ridge portion and extending in the longitudinal direction; each of the reinforcing members includes four fifth ridge portions formed to be continuous with each of the first ridge portion, the second ridge portion, the third ridge portion, and the fourth ridge portion, each of the fifth ridge portions extending in the longitudinal direction to the outside of the battery tray.

2. A battery unit as described in claim 1, wherein the top plate includes a first bead extending in the longitudinal direction, and the reinforcing member further includes a second bead formed continuous with the first bead and extending in the longitudinal direction.

3. A battery unit according to claim 1, wherein the cooling member is formed of an aluminum-based plated steel sheet.

4. A battery unit according to claim 1, wherein the cooling member is formed of a zinc-based plated steel sheet, and a chemical conversion coating is formed on the surface of the zinc-based plated steel sheet.

5. A battery unit according to any one of claims 1 to 4, wherein the cooling member has a Vickers hardness of 130 HV or more.

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