Lower box body for battery pack

Abstract

The utility model provides a lower box body for a battery pack, which comprises a heat exchange plate and a frame, the heat exchange plate is provided with a first side and a second side which are oppositely arranged in a first direction, and the first side of the heat exchange plate is provided with a heat exchange surface which is used for bearing a battery module and exchanging heat with the battery module; the frame is connected to the second side of the heat exchange plate; the frame comprises a first edge beam and a second edge beam, the first edge beam comprises a first beam body and a first convex eave, the first beam body and the first convex eave are arranged in the second direction, the first convex eave is connected to one side, in the third direction, of the first beam body, the heat exchange plate is connected with the first beam body and the first convex eave at the same time, and the first direction, the second direction and the third direction intersect pairwise. According to the lower box body, the first convex eave is additionally arranged on the inner side of the first beam body, the connecting area of the first edge beam is increased, the heat exchange plate can be connected with the first edge beam and can also be connected with the first convex eave, then the connecting strength is improved, and the bearing capacity of the lower box body is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of energy storage, in particular to a lower box body for battery pack. BACKGROUND

[0002] With the development of new energy storage system, the development direction of battery is towards large capacity and large size, and for the commonly used lithium iron phosphate battery of energy storage, the increasing battery capacity further increases the size and weight of the battery.

[0003] In some related technologies, a long lower box body is usually used in the battery pack, which can carry two 13-string battery modules in the length direction, and there is a middle module beam in the middle of the lower box body, but when the battery weight is large and the number of battery groups exceeds 13, such as 16 or more, the carrying capacity of the lower box body is insufficient, thereby limiting the energy density of the battery pack. SUMMARY

[0004] The utility model aims at at least solve the problem of insufficient carrying capacity of the lower box body of the battery pack in the prior art, and proposes a lower box body for battery pack.

[0005] To achieve the purpose of the utility model, a lower box body for battery pack is provided, which comprises: a heat exchange plate and a frame, the heat exchange plate has a first side and a second side arranged opposite in a first direction, the first side of the heat exchange plate has a heat exchange surface for carrying a battery module and exchanging heat with the battery module; the frame is connected to the second side of the heat exchange plate; the frame comprises: a first edge beam, which comprises: a first beam body and a first eave, the first beam body and the first eave are arranged along a second direction, the first eave is connected to one side of the first beam body in a third direction, the heat exchange plate is connected to the first beam body and the first eave, and the first direction, the second direction and the third direction intersect with each other.

[0006] Optionally, the lower box body further comprises: a support plate, the frame has a first side and a second side, the support plate is connected to the first side of the frame, and the heat exchange plate is connected to the second side of the frame; in the first direction, the support plate has a plurality of protruding portions, and the protruding portions abut against the heat exchange plate.

[0007] Optionally, the first beam body has a first connecting surface and a second connecting surface arranged opposite in the first direction; the first eave has a third connecting surface and a fourth connecting surface arranged opposite in the first direction; the support plate is connected to the first connecting surface and the third connecting surface respectively, and the heat exchange plate is connected to the second connecting surface and the fourth connecting surface respectively.

[0008] Optionally, the heat exchange plate comprises: a heat conduction plate having oppositely arranged first and second sides in the first direction, the heat exchange surface being located on the first side of the heat conduction plate, and the second side of the heat conduction plate having a buckling surface; a flow channel plate buckled with the buckling surface of the heat conduction plate, the edges of the flow channel plate being connected with the heat conduction plate and the fourth connecting surface respectively; and a second folded edge connected on both sides of the heat conduction plate in the third direction, the second folded edge being riveted with the second connecting surface.

[0009] Optionally, in the third direction, the first edge beam is parallel to two first edge beams, and the support plate is connected to the two first edge beams at both ends in the third direction; the frame further comprises: a second edge beam and a connecting plate, the second edge beam being arranged in the third direction, and both ends of the second edge beam being connected with the first ends of the two first edge beams respectively; and the connecting plate being arranged in the third direction, and both ends of the connecting plate being connected with the second ends of the two first edge beams respectively, so that the first edge beam, the second edge beam and the connecting plate form a frame-shaped structure.

[0010] Optionally, in the second direction, the heat conduction plate has a first end and a second end, and the first end of the heat conduction plate is used to be connected with the connecting plate; at the first end of the heat conduction plate, a transition structure is formed at the connection position between the second folded edge and the heat conduction plate, the transition structure has a first abutting surface facing away from the connecting plate and a second abutting surface facing the connecting plate, the first abutting surface is connected with the heat exchange surface and forms an obtuse angle, and the second abutting surface is connected with the buckling surface and forms an obtuse angle; the connecting plate is provided with a support boss corresponding to the transition structure, and the support boss is in contact with and abuts against the second abutting surface.

[0011] Optionally, in the third direction, the support plate has oppositely arranged two ends, and the two ends of the support plate are respectively formed with a first folded edge, and the first folded edge is connected with the first connecting surface; the protruding part comprises: a first protrusion, the first protrusion is at least one pair, and the same pair of first protrusions are arranged on both ends of the support plate and close to the first folded edge, and the first protrusion is connected with the third connecting surface.

[0012] Optionally, the first connecting surface is provided with a mounting groove, and the first folded edge is located in the mounting groove.

[0013] Optionally, the protruding part comprises: a second protrusion, the second side of the heat exchange plate has a connecting protrusion corresponding to the second protrusion, the second protrusion abuts against the connecting protrusion, a connecting piece is arranged on the second protrusion, and the connecting piece fixedly connects the second protrusion and the connecting protrusion, so that the heat exchange plate and the support plate clamp and fix the frame.

[0014] Optionally, the second protrusions and the connecting protrusions are multiple, and each of the second protrusions corresponds to one of the connecting protrusions.

[0015] Optionally, the second protrusions are multiple groups, and the multiple groups of the second protrusions are distributed in the second direction, and the same group of the second protrusions are distributed in the third direction.

[0016] Optionally, the support plates are multiple, and each of the support plates is arranged along the third direction, and all of the support plates are distributed in the second direction, and the second protrusions on all of the support plates are arranged one by one corresponding to the connecting protrusions.

[0017] Optionally, the heat exchange plate comprises: a heat conduction plate, the heat exchange surface is located on the heat conduction plate, and the connecting protrusions are located on the side of the heat conduction plate away from the heat exchange surface; a flow channel plate is buckled with the side of the heat conduction plate away from the heat exchange surface, the flow channel plate is provided with avoiding openings corresponding to the connecting protrusions, and the connecting protrusions are arranged in the avoiding openings.

[0018] Optionally, the first grooves are formed at positions corresponding to the connecting protrusions on the heat exchange surface.

[0019] Optionally, the side of the support plate facing the heat exchange plate is provided with a reinforcing rib along the third direction; in the third direction, multiple protruding parts are distributed on the reinforcing rib in the second direction, and avoiding grooves are formed between adjacent protruding parts in the second direction; the heat exchange plate has a first refrigerant flow channel arranged along the second direction inside, and the outer wall of the first refrigerant flow channel forms a protruding structure on the second side of the heat exchange plate, the protruding structure is arranged in the avoiding groove, and the protruding structure and the inner wall of the avoiding groove are in clearance fit.

[0020] Optionally, the protruding part comprises: multiple third protrusions, and the avoiding groove is arranged between adjacent two third protrusions; the first refrigerant flow channel is multiple, and multiple first refrigerant flow channels are distributed in the third direction, the outer wall of each first refrigerant flow channel corresponds to form a protruding structure on the second side of the heat exchange plate, and a second groove is formed between adjacent two protruding structures; each third protrusion corresponds to one second groove, and each third protrusion is arranged in the corresponding second groove.

[0021] Optionally, the reinforcing rib is multiple, and multiple reinforcing ribs are distributed in the second direction, and multiple protruding parts are arranged on each reinforcing rib, and the protruding parts on different reinforcing ribs correspond to each other in the second direction.

[0022] The lower box body of the utility model increases the first eave on the inner side of the first beam body, increases the connecting area of the first side beam, makes the heat exchange plate not only can be connected with the first side beam, but also can be connected with the first eave, further improves the connecting strength, further improves the carrying capacity of the lower box body. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The structure schematic view of the lower box body of the utility model embodiment is shown in the figure;

[0024] Figure 2 The structure schematic view of the first side beam of the utility model embodiment is shown in the figure;

[0025] Figure 3 The side view of the lower box body of the utility model embodiment is shown in the figure;

[0026] Figure 4 The structure schematic view of the frame and the support plate of the utility model embodiment is shown in the figure; Figure 3

[0027] Figure 5 The structure schematic view of the support plate of the utility model embodiment is shown in the figure;

[0028] Figure 6 The structure schematic view of the support plate of the utility model embodiment is shown in the figure;

[0029] Figure 7 The structure schematic view of the support plate of the utility model embodiment is shown in the figure; Figure 3

[0030] The structure schematic view of the support plate of the utility model embodiment is shown in the figure; Figure 8 Figure 3 The structure schematic view of the support plate of the utility model embodiment is shown in the figure;

[0031] Figure 9 The structure schematic view of the back of the flow channel plate of the utility model embodiment is shown in the figure;

[0032] Figure 10 The structure schematic view of the back of the flow channel plate of the utility model embodiment is shown in the figure;

[0033] LIST OF REFERENCE NUMERALS

[0034] ​​10, heat exchange plate; 11, heat conduction plate; 111, heat exchange surface; 112, buckling surface; 113, connecting protrusion; 114, first groove; 12, flow channel plate; 121, avoiding opening; 122, first flow channel groove; 123, second flow channel groove; 124, protrusion structure; 125, second groove; 126, buffer groove; 13, second folding edge; 14, third folding edge; 15, transition structure; 151, first abutting surface; 152, second abutting surface; 20, frame; 21, first edge beam; 211, first beam body; 2111, first connecting surface; 2112, second connecting surface; 212, first eave; 2121, third connecting surface; 2122, fourth connecting surface; 22, second edge beam; 221, second beam body; 222, second eave; 213, mounting groove; 214, hoisting hole; 23, connecting plate; 231, supporting boss; 232, connecting boss; 233, pressing boss; 30, supporting plate; 31, plate body; 311, first folding edge; 32, reinforcing rib; 33, protrusion part; 331, first protrusion; 332, second protrusion; 333, third protrusion; 34, avoiding groove; 40, connecting piece. DETAILED DESCRIPTION

[0035] In order for those skilled in the art to better understand the technical scheme of the utility model, the lower box provided by the utility model is described in detail below in combination with the drawings.

[0036] With the development of new energy storage systems, the development direction of batteries is towards large capacity and large size. For the commonly used lithium iron phosphate battery for energy storage, the increasing battery capacity further increases the size and weight of the battery itself.

[0037] In some related technologies, a long lower box is usually used in the battery pack, which can carry two 13-string battery modules in the length direction. The middle module beam is in the middle of the lower box, but when the battery weight is large and the number of battery groups exceeds 13 strings, such as 16 strings or more, the carrying capacity of the lower box may be insufficient, thereby limiting the energy density of the battery pack.

[0038] The existing lower box usually includes a cold plate, a frame and a reinforcing plate, which are used to cool the battery module. The frame is connected around the cold plate as the main body for carrying the weight, and the reinforcing plate is connected to the frame for reinforcing the frame structure to improve the carrying capacity.

[0039] Under normal circumstances, the cold plate needs to select aluminum profiles with good heat conduction performance. In order to ensure the reliability of welding with the cold plate, the frame and the reinforcing rib are usually made of the same material, that is, aluminum profiles. However, the carrying capacity of aluminum profiles is poorer than that of steel profiles, which may result in poor overall carrying capacity of the lower box.

[0040] Although the steel profile is stronger than the aluminum profile, the heat conduction performance is poor, so if the steel profile is used as the cold plate material, the heat conduction efficiency will be reduced, thereby affecting the cooling effect of the battery module on the cold plate.

[0041] In addition, in the existing frame structure, the edge beam structure is relatively simple, and the contact area with the heat exchange plate is limited, which also causes the unreliable connection of the heat exchange plate and the frame, thereby affecting the carrying capacity of the lower box.

[0042] To solve the above problems, as shown in the utility model discloses a lower box for with battery pack. Figures 1 to 10 Battery pack includes: lower box, battery module and upper cover, the upper cover is buckled on the lower box and encloses the containing cavity, the battery module is connected on the lower box and is located in the containing cavity.

[0043] As shown in the utility model discloses a lower box for with battery pack. Figure 1 The heat exchange plate 10 has a first side and a second side oppositely arranged in the first direction, and the first side of the heat exchange plate 10 has a heat exchange surface 111 for carrying the battery module and exchanging heat with the battery module; the frame 20 is connected to the second side of the heat exchange plate 10.

[0044] It should be noted that in the embodiment, the thickness direction of the lower box is arranged along the first direction, that is, the x-axis direction in the figure; the length direction of the lower box is arranged along the second direction, that is, the y-axis direction in the figure; the width direction of the lower box is arranged along the third direction, that is, the z-axis direction in the figure, and the first direction, the second direction and the third direction are perpendicular to each other.

[0045] As shown in the utility model discloses a lower box for with battery pack. Figure 1 And Figure 2 The first edge beam 21 is arranged along the second direction and has a first end and a second end, the first edge beam 21 is two, the two first edge beams 21 are arranged in the third direction and are parallel to each other; the second edge beam 22 is arranged along the third direction, and the two ends of the second edge beam 22 are connected with the first ends of the two first edge beams 21 respectively; the connecting plate 23 is arranged along the third direction, and the two ends of the connecting plate 23 are connected with the second ends of the two first edge beams 21 respectively, and the first edge beam 21, the second edge beam 22 and the connecting plate 23 form a frame-shaped structure.

[0046] As shown in the utility model discloses a lower box for with battery pack. Figure 1 And Figure 2As shown, the first side beam 21 comprises: a first beam body 211 and a first eave 212, both of which are arranged along the second direction, and the first eave 212 is connected to one side of the first beam body 211 in the third direction, and the heat exchange plate 10 is connected with the first beam body 211 and the first eave 212 at the same time. In other words, the first eave 212 is located on the side of the first beam body 211 facing the other first side beam 21, that is, the inner side of the first beam body 211.

[0047] The lower box body of the utility model increases the first eave 212 on the inner side of the first beam body 211, increases the connecting area of the first side beam 21, so that the heat exchange plate 10 can be connected with not only the first side beam 21 but also the first eave 212, thereby improving the connecting strength and further improving the carrying capacity of the lower box body.

[0048] It should be noted that the frame 20 and the heat exchange plate 10 are different in material, the thermal conductivity of the material used for the heat exchange plate 10 is not less than that of the material used for the frame 20, and the yield strength of the material used for the frame 20 is not less than that of the material used for the heat exchange plate 10.

[0049] Compared with the prior art, because the frame 20 and the heat exchange plate 10 are different in material, the heat exchange plate 10 can select a material with higher thermal conductivity, and the frame 20 can select a material with higher yield strength, so that the carrying capacity of the lower box body is improved while the heat dissipation effect on the battery module is ensured. However, due to the difference in material between the frame 20 and the heat exchange plate 10, the frame 20 and the heat exchange plate 10 cannot be directly fixed and connected by welding. If the two cannot be fixed and connected, the heat exchange plate 10 and the frame 20 cannot be effectively fixed, which will reduce the carrying capacity of the lower box body. The frame 20 and the heat exchange plate 10 of the utility model are fixed and connected by riveting or screwing, which is not affected by different materials, so that reliable connection of the frame 20 and the heat exchange plate 10 is realized, and the carrying capacity of the lower box body is improved.

[0050] It can be understood that the heat exchange plate 10 can be made of aluminum alloy, copper alloy or the like, and the frame 20 can be made of alloy steel, titanium alloy or the like. The frame 20 and the heat exchange plate 10 can be screwed or riveted.

[0051] Further, the thermal conductivity of the material used for the heat exchange plate 10 is greater than that of the material used for the frame 20, and the yield strength of the material used for the frame 20 is greater than that of the material used for the heat exchange plate 10.

[0052] Exemplarily, the heat exchange plate 10 is made of aluminum alloy, the frame 20 is made of alloy steel (for example, high-strength steel), and the heat exchange plate 10 is riveted to the frame 20, for example, by using a SPR riveting process. By using aluminum alloy as the material of the heat exchange plate 10, since the thermal conductivity of aluminum alloy is generally between 130-220 W / (m·K), and the thermal conductivity of alloy steel is generally between 10-50 W / (m·K), the aluminum alloy has excellent thermal conductivity compared with the alloy steel, thereby ensuring the heat exchange efficiency of the heat exchange plate 10 and the battery module. Meanwhile, the yield strength of the aluminum alloy is generally between 280 MPa and 320 MPa, and the yield strength of some alloy steels can reach 600 MPa or more, so that the use of the alloy steel as the frame 20 can effectively increase the load capacity of the lower box. By riveting, the heat exchange plate 10 and the frame 20 can be fixedly connected, the heat exchange is ensured, the lower box forms an integral whole, and the load capacity of the lower box is improved.

[0053] As shown in Figures 3 to 6 As shown in Figure 3 The frame 20 has a first side and a second side, the support plate 30 is connected to the first side of the frame 20, and the heat exchange plate 10 is connected to the second side of the frame 20. As shown in Figure 4 In the first direction, the support plate 30 has a plurality of protruding portions 33, and the protruding portions 33 abut against the second side of the heat exchange plate 10. By connecting the support plate 30 and the heat exchange plate 10 to the two sides of the frame 20 respectively, the heat exchange plate 10, the frame 20 and the support plate 30 form an integral whole, and the load capacity of the lower box is improved. In addition, the plurality of protruding portions 33 on the support plate 30 abut against the second side of the heat exchange plate 10, which can support the heat exchange plate 10 in the first direction, and further improve the structural strength, thereby preventing the heat exchange plate 10 from deforming.

[0054] The material of the support plate 30 is the same as that of the frame 20, the heat exchange plate 10 is riveted to the frame 20, and the frame 20 is welded to the support plate 30. By making the material of the frame 20 the same as that of the support plate 30, the strength of the frame 20 and the support plate 30 is improved, and since the materials of the frame 20 and the support plate 30 are the same, the frame 20 and the support plate 30 can be reliably connected by welding. Although the materials of the heat exchange plate 10 and the frame 20 are different, the heat exchange plate 10 and the frame 20 can be reliably connected by riveting.

[0055] As shown in Figure 5As shown, in the embodiment, the support plates 30 are multiple, the length direction of each support plate 30 is arranged along the third direction, and the width direction is arranged along the second direction. In the third direction, the two ends of the support plate 30 are connected to the frame 20 respectively. The multiple support plates 30 are distributed in the second direction. Each support plate 30 abuts against the heat exchange plate 10, and multiple-point support can be formed on the heat exchange plate 10, so that the heat exchange plate 10 is uniformly supported, thereby improving the overall strength.

[0056] As shown in FIG. 1, the first beam body 211 extends along the second direction, and the second beam body 212 extends along the first direction. Figure 5 As shown in FIG. 1, the first beam body 211 extends along the second direction, and the second beam body 212 extends along the first direction. Figure 2 As can be seen, the first beam body 211 has the first connecting surface 2111 and the second connecting surface 2112 arranged oppositely in the first direction, the first connecting surface 2111 is located on the first side of the frame 20, and the second connecting surface 2112 is located on the second side of the frame 20. The first eave 212 has the third connecting surface 2121 and the fourth connecting surface 2122 arranged oppositely in the first direction, the third connecting surface 2121 is located on the first side of the frame 20, and the fourth connecting surface 2122 is located on the second side of the frame 20.

[0057] As shown in FIG. 1, the first beam body 211 extends along the second direction, and the second beam body 212 extends along the first direction. Figure 4 As shown in FIG. 1, the first beam body 211 extends along the second direction, and the second beam body 212 extends along the first direction.

[0058] As shown in FIG. 1, the first beam body 211 extends along the second direction, and the second beam body 212 extends along the first direction. Figure 6 As shown in FIG. 1, the first beam body 211 extends along the second direction, and the second beam body 212 extends along the first direction.

[0059] It should be noted that in the embodiment, the reinforcing ribs 32 are five, but this is not restrictive, in some other embodiments not shown in the figure, the number of reinforcing ribs 32 can be one, two, three, four or six, etc. In some other embodiments not shown in the figure, no reinforcing ribs 32 can be provided, and the protruding part 33 can be directly provided on the plate body 31, which is also feasible. However, in the embodiment, the reinforcing ribs 32 are provided to improve the strength of the support plate 30, thereby effectively improving the load-carrying capacity of the lower box.

[0060] As shown in Figure 6 , the plate body 31 of the support plate 30 has two ends arranged in the third direction, and the plate body 31 of the support plate 30 has a first folded edge 311 formed at each end. Figure 2 and Figure 4 As shown, the support plate 30 is connected to the first connecting surface 2111 through the first folded edge 311.

[0061] As shown in Figure 6 , the protruding part includes a first protrusion 331. The first protrusion 331 is at least one pair, as shown in Figure 6 , each reinforcing rib 32 is provided with two first protrusions 331, and the two first protrusions 331 are located at the two ends of the same reinforcing rib 32 and close to the first folded edge 311. As shown in Figure 2 and Figure 4 , the first protrusion 331 is connected to the third connecting surface 2121.

[0062] By adding the first eave 212 to the inner side of the first beam body 211, the connecting area of the first edge beam 21 is increased, so that the support plate 30 can not only be welded to the first connecting surface 2111 of the first edge beam 21 through the first folded edge 311, but also be welded to the third connecting surface 2121 of the first eave 212 through the first protrusion 331, thereby improving the connection strength. And since the heat exchange plate 10 is also connected to the other side of the first eave 212, the support of the heat exchange plate 10 can also be achieved. At the same time, on the other hand, the first protrusion 331 of the support plate 30 and the heat exchange plate 10 can clamp and fix the first eave 212, thereby improving the overall connection strength and thereby improving the load-carrying capacity of the lower box.

[0063] As shown in Figure 2 and Figure 4As shown, the first connecting surface 2111 is provided with a mounting groove 213, and the first folded edge 311 is located in the mounting groove 213. By providing the mounting groove 213 on the first connecting surface 2111, the first folded edge 311 can be positioned by cooperating with the mounting groove 213 when the mounting support plate 30 is installed. At the same time, after the first folded edge 311 is welded with the mounting groove 213, the mounting groove 213 limits the first folded edge 311, improves the reliability of the connection, and because the first folded edge 311 is located in the mounting groove 213, the first folded edge 311 will not protrude from the first connecting surface 2111. By adjusting the thickness of the first folded edge 311 to match the thickness of the mounting groove 213, the surface of the first folded edge 311 can be located in the same plane as the first connecting surface 2111, so that after the battery pack is placed on the battery support, the first folded edge 311 and the first connecting surface 2111 can be supported on the support surface of the battery support together, so that the stress is more uniform and stress concentration is avoided.

[0064] It should be noted that in the present embodiment, the cross section of the first beam body 211 is a rectangular structure, which is formed by high-strength steel rolling, so the strength is high. Figure 5 As shown, a hoisting hole 214 for hoisting is arranged on the side of the first beam body 211 away from the other first side beam 21, that is, the outer side of the first beam body 211, so as to facilitate hoisting.

[0065] As shown, Figure 1 As shown, the heat exchange plate 10 includes a heat conducting plate 11, a flow channel plate 12, a second folded edge 13 and a third folded edge 14. In the first direction, the heat conducting plate 11 has oppositely arranged first and second sides, and the heat exchange surface 111 is located on the first side of the heat conducting plate 11, and the second side of the heat conducting plate 11 has a buckling surface 112. The flow channel plate 12 is buckled and welded with the buckling surface 112 of the heat conducting plate 11.

[0066] As shown, Figure 1 As shown in the second direction, the heat conducting plate 11 has a first end and a second end, the first end of the heat conducting plate 11 is used for connecting with the connecting plate 23, and the third folded edge 14 is connected to the second end of the heat conducting plate 11, and the second end of the heat conducting plate 11 is used for connecting with the second side beam 22.

[0067] As shown, Figure 1 As shown in the third direction, the heat conducting plate 11 has a first side and a second side, the first side and the second side are respectively provided with the second folded edge 13, and the second folded edge 13 extends from the first end to the second end of the heat conducting plate 11.

[0068] As shown, Figure 4As shown, the second fold edge 13 is connected to the two side edges of the heat-conducting plate 11 in the second direction, and the second fold edge 13 is riveted with the second connecting surface 2112. The side edges of the flow channel plate 12 in the third direction are connected to the heat-conducting plate 11 and the fourth connecting surface 2122 respectively. By providing the second fold edge 13 on both sides of the heat-conducting plate 11 and riveting the second fold edge 13 with the second connecting surface 2112, the fixed connection of the heat exchange plate 10 and the first side beam 21 is realized. At the same time, the edges of the flow channel plate 12 are connected to the heat-conducting plate 11 and the fourth connecting surface 2122 respectively, which is equivalent to supporting the heat exchange plate 10 through the first eaves 212, and further improves the carrying capacity of the heat exchange plate 10 in cooperation with the first protrusion 331.

[0069] As an example, since the material of the first side beam 21 is different from that of the heat exchange plate 10, the fixed connection between the first eaves 212 and the heat exchange plate 10 is realized by bonding to improve the overall strength of the lower box body.

[0070] It can be understood that the second side beam 22 includes a second beam body 221 and a second eaves 222, and the second beam body 221 and the second eaves 222 are arranged along the third direction. The second eaves 222 is arranged on the side of the second beam body 221 facing the connecting plate 23. Correspondingly, the third fold edge 14 corresponds to the second side beam 22 and is riveted on the second beam body 221, and the side edge of the flow channel plate 12 corresponding to the second side beam 22 is connected to the second eaves 222. By arranging the second eaves 222 on the second beam body 221, a support can be formed in the third direction through the second eaves 222, thereby further improving the carrying capacity of the heat exchange plate 10.

[0071] When the rear module beam needs to be arranged on the heat exchange plate 10, the arrangement position of the rear module beam corresponds to the position of the second eaves 222, and the second eaves 222, the heat exchange plate 10 and the rear module beam are sequentially connected to fix the second end of the module unit to the rear module beam. As an example, the pull rivet nut sequentially fixes the second eaves 222, the heat exchange plate 10 and the rear module beam from bottom to top.

[0072] As shown in Figure 1 and Figure 8 At the first end of the heat-conducting plate 11, a transition structure 15 is formed at the connection position of the second fold edge 13 and the heat-conducting plate 11, and at the second end of the heat-conducting plate 11, the second fold edge 13 is connected to the third fold edge 14.

[0073] As shown in Figure 8 The transition structure 15 has a first abutting surface 151 away from the connecting plate 23 and a second abutting surface 152 towards the connecting plate 23, the first abutting surface 151 is connected to the heat exchange surface 111 and forms an obtuse angle, and the second abutting surface 152 is connected to the buckling surface 112 and forms an obtuse angle. As shown in Figure 8As shown, the exemplary transition structure 15 is a transition plate, and the two sides of the transition plate in the first direction are a first abutting surface 151 and a second abutting surface 152.

[0074] As shown, the connecting plate 23 is provided with a support boss 231 corresponding to the transition plate, and the support boss 231 is in contact with and abuts against the second abutting surface 152 of the transition plate. Figure 1 and Figure 9 As shown, the connecting plate 23 is provided with a support boss 231 corresponding to the transition plate, and the support boss 231 is in contact with and abuts against the second abutting surface 152 of the transition plate.

[0075] As shown, the transition structure 15 is two, one on each side of the first end of the heat conduction plate 11, and the support boss 231 is also two, one for each transition structure 15. Figure 1 As shown, the connecting plate 23 is provided with a support boss 231 on each end in the third direction, and a pressing boss 233 is provided between the two support bosses 231. Figure 9 As shown, the connecting plate 23 is provided with a support boss 231 on each end in the third direction, and a pressing boss 233 is provided between the two support bosses 231.

[0076] It should be noted that the transition structure 15 and the support boss 231 are riveted together by a pull rivet nut, and the pressing edge of the upper cover is fixedly connected with the transition structure 15 by a bolt, the bolt penetrates the pressing edge of the upper cover and is screwed with the pull rivet nut on the transition structure 15 to achieve fixed connection, so that the pressing edge of the upper cover is in close contact with the transition structure 15, thereby improving the sealing performance.

[0077] Similarly, the area of the heat conduction plate 11 between the two transition structures 15 and the pressing boss 233 are also riveted together by a pull rivet nut, and the pressing edge of the upper cover is also fixedly connected with the heat conduction plate 11 by a bolt, the bolt penetrates the pressing edge of the upper cover and is screwed with the pull rivet nut on the heat conduction plate 11 to achieve fixed connection, so that the pressing edge of the upper cover is in close contact with the heat conduction plate 11, thereby improving the sealing performance.

[0078] As shown, the transition structure 15 is two, one on each side of the first end of the heat conduction plate 11, and the support boss 231 is also two, one for each transition structure 15. Figure 9As shown, the connecting plate 23 is further provided with a plurality of connecting bosses 232, the connecting bosses 232 are spaced apart along the third direction, all the connecting bosses 232 correspond to the front module beam, the connecting bosses 232 are provided with connecting holes, the connecting bosses 232 are used for connecting with the heat exchange plate 10 and the front module beam, so that the first end of the module unit is fixedly connected with the front module beam.

[0079] As shown, the heat exchange plate 10 and the front module beam are connected through a pull rivet nut, and the connecting plate 23 is fixedly connected with the heat exchange plate 10 through a bolt. The pull rivet nut is sequentially riveted from bottom to top to the flow channel plate 12, the heat conduction plate 11 of the heat exchange plate 10 and the lower end face of the front module beam, and the bolt is also threaded from bottom to top in the connecting hole of the connecting boss 232 and is threadedly connected with the pull rivet nut, so that the connecting plate 23 is fixedly connected with the heat exchange plate 10 and the front module beam.

[0080] As shown in Figure 6 and Figure 7 , the protruding part 33 comprises: a second protrusion 332, the second side of the heat exchange plate 10 has a connecting protrusion 113 corresponding to the second protrusion 332, the second protrusion 332 abuts against the connecting protrusion 113, and the connecting member 40 is threaded on the second protrusion 332 and fixedly connects the second protrusion 332 and the connecting protrusion 113. That is, the support plate 30 is fixedly connected with the heat exchange plate 10 through the connecting member 40.

[0081] As shown in Figure 6 and Figure 7 , it can be seen that among all the protruding parts 33, the second protrusion 332 is used for riveting with the heat exchange plate 10. As shown in Figure 7 , the second side of the heat exchange plate 10 has a connecting protrusion 113 corresponding to the second protrusion 332, the second protrusion 332 abuts against the connecting protrusion 113, and the connecting member 40 is threaded on the second protrusion 332 and fixedly connects the second protrusion 332 and the connecting protrusion 113, so that the heat exchange plate 10 and the support plate 30 clamp and fix the frame 20.

[0082] The lower box body of the utility model is fixedly connected with the heat exchange plate 10 through the connecting member 40 by setting the second protrusion 332 on the support plate 30 and the corresponding connecting protrusion 113 on the heat exchange plate 10 and threading the connecting member 40 on the second protrusion 332, the heat exchange plate 10 and the support plate 30 clamp and fix the frame 20. Thus, the heat exchange plate 10, the frame 20 and the support plate 30 are connected with each other in pairs, the whole lower box body forms a whole, the strength of the whole is improved, the carrying capacity of the lower box body is improved, the middle module beam can be omitted, more battery modules can be carried, and the energy density of the battery pack is improved. Moreover, after the support plate 30 and the heat exchange plate 10 are connected, additional clamping force can be provided to clamp and fix the frame 20, and the connection strength is improved.

[0083] In addition, by forming the connecting protrusion 113 on the second side of the heat exchange plate 10, on the one hand, the effective contact can be formed in cooperation with the second protrusion 332, and the reliable connection can be realized in cooperation with the connecting piece 40. On the other hand, due to the presence of the connecting protrusion 113, a certain distance is formed between the connecting position of the second protrusion 332 and the connecting protrusion 113 and the heat exchange surface 111, which can avoid the deformation of the connecting position when connecting to form the protrusion of the heat exchange surface 111, thereby avoiding the poor contact between the battery module and the heat exchange surface 111, and ensuring the heat dissipation effect of the battery module.

[0084] It can be understood that, as before, the support plate 30 and the heat exchange plate 10 are different in material, the thermal conductivity coefficient of the material used by the heat exchange plate 10 is greater than the thermal conductivity coefficient of the material used by the support plate 30, and the yield strength of the material used by the support plate 30 is greater than the yield strength of the material used by the heat exchange plate 10.

[0085] In combination with Figure 1 , Figure 5 and Figure 7 It can be seen that in the embodiment, the second protrusion 332 and the connecting protrusion 113 are both multiple, and each second protrusion 332 corresponds to a connecting protrusion 113. Thus, the reliability of the connection is improved.

[0086] Specifically, as shown in Figure 6 , the second protrusion 332 is multiple groups, and the multiple groups of second protrusions 332 are distributed in the second direction, and the second protrusions 332 in the same group are distributed in the third direction. In other words, the second protrusions 332 in the same group are located on the same reinforcing rib 32, while the second protrusions 332 in different groups are located on different reinforcing ribs 32, thereby forming a matrix distribution. By forming a matrix distribution, a single support plate 30 and a heat exchange plate 10 are connected and fixed by the second protrusions 332 and the connecting protrusions 113 in a matrix distribution, so that the stress points are more dispersed and the stress is more uniform, thereby reducing stress concentration.

[0087] It should be noted that the second protrusions 332 on each reinforcing rib 32 can be the same or different, and the number of second protrusions 332 provided on the reinforcing rib 32 is not limited, which can be zero, one, two, three, etc. Taking the present embodiment as an example, three second protrusions 332 are provided on each of the two reinforcing ribs 32 located at the outermost side, two second protrusions 332 are provided on the middle reinforcing rib 32, and no second protrusions 332 are provided on the remaining two reinforcing ribs 32. Moreover, the second protrusions 332 on different reinforcing ribs 32 correspond to each other in the second direction, for example: Figure 6The second protrusions 332 on the two outermost reinforcing ribs 32 are arranged one by one in correspondence, and the two second protrusions 332 on the middle reinforcing rib 32 also correspond to the other two second protrusions 332 in the third direction.

[0088] It can be understood that when the support plates 30 are multiple, the second protrusions 332 on all the support plates 30 are arranged one by one in correspondence with all the connecting protrusions 113. Thus, the weight borne by the heat exchange plate 10 can be evenly dispersed to each support plate 30, and then further dispersed through each second protrusion 332 and the connecting protrusion 113, so as to reduce stress concentration and improve the carrying capacity of the lower box.

[0089] For example, each second protrusion 332 is riveted with the corresponding connecting protrusion 113, so that each support plate 30 is riveted with the heat exchange plate 10, forming a multi-point connection to disperse the stress generated by the connection and avoid stress concentration.

[0090] In the embodiment, as shown in Figure 1 and Figure 7 , the flow channel plate 12 is provided with an avoiding opening 121 corresponding to the connecting protrusion 113, and the connecting protrusion 113 is arranged in the avoiding opening 121.

[0091] In combination with Figure 7 , it can be seen that the connecting protrusion 113 is located on the side of the heat conduction plate 11 away from the heat exchange surface 111, that is, on the buckling surface 112, and the flow channel plate 12 is provided with an avoiding opening 121 corresponding to the connecting protrusion 113. After the flow channel plate 12 is buckled with the heat exchange plate 10, the connecting protrusion 113 passes through the avoiding opening 121, so as to abut against the second protrusion 332. By adopting this arrangement mode, after the heat conduction plate 11 is riveted with the support plate 30, a clamping force is formed between the two, so that the flow channel plate 12 can be more closely attached to the heat conduction plate 11, improving the reliability of the connection between the heat conduction plate 11 and the flow channel plate 12.

[0092] As shown in Figure 7 , a first groove 114 is formed on the heat exchange surface 111 at a position corresponding to the connecting protrusion 113. That is, the connecting protrusion 113 is formed on the side of the heat conduction plate 11 away from the heat exchange surface 111. Therefore, a first groove 114 is formed at a corresponding position on the heat exchange surface 111. By adopting this mode, after the second protrusion 332 is riveted with the connecting protrusion 113, due to the existence of the first groove 114, even if the riveting position is slightly deformed, it is located in the first groove 114 and will not cause deformation of the heat exchange surface 111. Therefore, the flatness of the heat exchange surface 111 can be guaranteed, so as to guarantee the effective contact between the heat exchange surface 111 and the battery module and the heat exchange efficiency.

[0093] As shown in Figure 1As shown, on the front side of the flow channel plate 12, that is, the side facing the heat exchange plate 11, a first flow channel groove 122 and a second flow channel groove 123 are respectively provided. The first flow channel groove 122 is arranged along the second direction, and there are multiple first flow channel grooves 122, which are spaced apart along the third direction. The second flow channel groove 123 is arranged along the third direction, and adjacent first flow channel grooves 122 are connected through the second flow channel groove 123. When the flow channel plate 12 is fastened and welded to the heat exchange plate 10, the fastening surface 112 of the first flow channel groove 122 and the heat exchange plate 10 forms a first refrigerant flow channel arranged along the second direction, and the fastening surface 112 of the second flow channel groove 123 and the heat exchange plate 10 forms a second refrigerant flow channel arranged along the second direction.

[0094] It is understandable that, such as Figure 10 As shown, a protruding structure 124 is formed on the second side of the heat exchange plate 10 on the outer wall of the first refrigerant channel. This is because the first channel groove 122 is formed by recessing from the front to the back of the channel plate 12. Therefore, as... Figure 10 As shown, on the back side of the flow channel plate 12, that is, the side away from the heat exchange plate 10, a protruding structure 124 is formed at the position corresponding to the first flow channel groove 122. The back side of the flow channel plate 12 is the second side of the heat exchange plate 10. The protruding structure 124 is also arranged along the second direction and corresponds one-to-one with the first flow channel groove 122, that is, the first refrigerant flow channel.

[0095] like Figure 6 As shown, a clearance groove 34 is formed between adjacent protrusions 33, extending in the third direction, as... Figure 4 As shown, the protruding structure 124 passes through the clearance groove 34, and the protruding structure 124 is clearance-fitted with the inner wall of the clearance groove 34. By forming the clearance groove 34 between adjacent protrusions 33, the protruding structure 124 formed on the back of the flow channel plate 12, that is, the second side of the heat exchange plate 10, is positioned in the clearance groove 34 and clearance-fitted with the clearance groove 34. This means the protruding structure 124 does not contact the inner wall of the clearance groove 34, thereby preventing flow channel breakage due to vibration, friction, or impact. Simultaneously, as... Figure 4 As shown, due to the riveting of the second protrusion 332 and the connecting protrusion 113, the positions of the protrusion structure 124 and the relief groove 34 are relatively fixed, which can further prevent the two from moving relative to each other, thereby effectively avoiding collisions or friction between them. Moreover, the support plate 30 can also play a certain protective role for the first refrigerant flow channel, improving the reliability of the heat exchange plate 10.

[0096] like Figure 6As shown, the protruding part 33 further comprises a third protrusion 333. The third protrusions 333 are multiple, the third protrusions 333 on the same reinforcing rib 32 are distributed in the third direction, and the third protrusions 333 on different reinforcing ribs 32 are corresponding in the second direction, and the third protrusions 333 adjacent to each other have an avoiding slot 34 between them.

[0097] It should be noted that an avoiding slot 34 is formed between two adjacent protruding parts 33, and the two protruding parts 33 can be the same or different. For example, the two adjacent protruding parts 33 are both third protrusions 333, that is, an avoiding slot 34 is formed between the two adjacent third protrusions 333; for another example, the two adjacent protruding parts 33 are a second protrusion 332 and a third protrusion 333 respectively, that is, an avoiding slot 34 is formed between the two adjacent second protrusion 332 and third protrusion 333; and for another example, the two adjacent protruding parts 33 are a third protrusion 333 and a first protrusion 331 respectively, that is, an avoiding slot 34 is formed between the two adjacent third protrusion 333 and first protrusion 331. Therefore, as long as the avoiding slot 34 formed between the two adjacent protruding parts 33, it is within the protection scope of the utility model without violating the principles and inventive concepts of the utility model.

[0098] As shown in the figure, Figure 10 Since the first refrigerant flow channel is multiple, the multiple first refrigerant flow channels are distributed in the third direction, that is, the outer wall of each first refrigerant flow channel corresponds to form a protruding structure 124 on the second side of the heat exchange plate 10, and a second groove 125 is formed between the two adjacent protruding structures 124.

[0099] As shown in the figure, Figure 4 Each third protrusion 333 corresponds to a second groove 125, and each third protrusion 333 abuts in the corresponding second groove 125. By abutting the third protrusion 333 in the second groove 125, the support area of the support plate 30 to the heat exchange plate 10 is increased, so that the weight of the heat exchange plate 10 can be more evenly transmitted to the support plate 30. Moreover, since the abutting position of the third protrusion 333 is located between the adjacent first refrigerant flow channels, the first refrigerant flow channels are avoided, and the risk of liquid leakage due to damage is avoided.

[0100] As shown in the figure, Figure 6 In the second direction, the protruding parts 33 on different reinforcing ribs 32 are corresponding. Since all the protruding parts 33 correspond to each other, the avoiding slots 34 are also corresponding, and the protruding structure 124 corresponding to each first refrigerant flow channel can pass through multiple corresponding avoiding slots 34, thereby avoiding abrasion.

[0101] As shown in the figure, Figure 1As shown, the flow channel plate 12 is further provided with a buffer groove 126. After the flow channel plate 12 is buckled and welded with the heat conduction plate 11, the buffer groove 126 and the buckling surface 112 form a closed cavity to buffer the deformation of the flow channel plate 12 caused by the heat received during welding. At the same time, the buffer groove 126 is used to accommodate the air discharged during welding of the flow channel plate 12 and the heat conduction plate 11, so as to prevent the air from forming bubbles between the connection interface of the heat conduction plate 11 and the flow channel plate 12, thereby preventing the heat exchange plate 10 from being deformed.

[0102] It can be understood that the above embodiments are only exemplary embodiments adopted for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. A lower cabinet for a battery pack, comprising: The heat exchange plate (10) has oppositely arranged first and second sides in a first direction, and the first side of the heat exchange plate (10) has a heat exchange surface (111) for carrying and exchanging heat with a battery module; the frame (20) is connected to the second side of the heat exchange plate (10); characterized in that the frame (20) comprises: A first edge beam (21) comprises a first beam body (211) and a first eave (212), both of which are arranged along a second direction, and the first eave (212) is connected to one side of the first beam body (211) in a third direction, and the heat exchange plate (10) is connected to the first beam body (211) and the first eave (212) at the same time, and the first direction, the second direction and the third direction intersect with each other.

2. The lower box according to claim 1, characterized in that, The lower box further comprises: A support plate (30), the frame (20) has a first side and a second side, the support plate (30) is connected to the first side of the frame (20), and the heat exchange plate (10) is connected to the second side of the frame (20); In the first direction, a plurality of protrusions (33) are provided on the support plate (30), and the protrusions (33) abut against the heat exchange plate (10).

3. The lower box of claim 2, wherein The first beam body (211) has oppositely arranged first and second connecting surfaces (2111) in the first direction; The first eave (212) has oppositely arranged third and fourth connecting surfaces (2121) in the first direction; The support plate (30) is connected to the first and third connecting surfaces (2111, 2121) respectively, and the heat exchange plate (10) is connected to the second and fourth connecting surfaces (2112, 2122) respectively.

4. The lower box according to claim 3, characterized in that, The heat exchange plate (10) comprises: A heat conduction plate (11) has oppositely arranged first and second sides in the first direction, and the heat exchange surface (111) is located on the first side of the heat conduction plate (11), and the second side of the heat conduction plate (11) has a buckling surface (112); A flow channel plate (12) is buckled to the buckling surface (112) of the heat conduction plate (11), and the edges of the flow channel plate (12) are connected to the heat conduction plate (11) and the fourth connecting surface (2122) respectively; A second folded edge (13) is connected to both sides of the heat conduction plate (11) in the third direction, and the second folded edge (13) is riveted to the second connecting surface (2112).

5. The lower box of claim 4, wherein In the third direction, the first edge beam (21) is parallel to two, and the two ends of the support plate (30) along the third direction are connected to the two first edge beams (21) respectively. The frame (20) further comprises a second edge beam (22) arranged along the third direction, two ends of the second edge beam (22) being connected with the first ends of the two first edge beams (21) respectively; The connecting plate (23) is arranged along the third direction, two ends of the connecting plate (23) being connected with the second ends of the two first edge beams (21) respectively, the first edge beam (21), the second edge beam (22) and the connecting plate (23) forming a frame-shaped structure.

6. The lower box according to claim 5, wherein, In the second direction, the heat-conducting plate (11) has a first end and a second end, the first end of the heat-conducting plate (11) being used for connecting with the connecting plate (23); At the first end of the heat-conducting plate (11), a transition structure (15) is formed at the connecting position of the second folding edge (13) and the heat-conducting plate (11), the transition structure (15) having a first abutting surface (151) facing away from the connecting plate (23) and a second abutting surface (152) facing toward the connecting plate (23), the first abutting surface (151) being connected with the heat-exchange surface (111) and forming an obtuse angle, the second abutting surface (152) being connected with the buckling surface (112) and forming an obtuse angle; The connecting plate (23) is provided with a support boss (231) corresponding to the transition structure (15), the support boss (231) being in close contact with and abutting against the second abutting surface (152).

7. The lower box according to claim 3, wherein, In the third direction, the support plate (30) has two ends arranged oppositely, the two ends of the support plate (30) being respectively formed with a first folding edge (311), the first folding edge (311) being connected with the first connecting surface (2111); The protruding part (33) comprises a first protrusion (331), the first protrusion (331) being at least one pair, the first protrusions (331) of the same pair being arranged at the two ends of the support plate (30) respectively and close to the first folding edge (311), the first protrusion (331) being connected with the third connecting surface (2121).

8. The lower box according to claim 7, wherein, The first connecting surface (2111) is provided with a mounting groove (213), the first folding edge (311) being located in the mounting groove (213).

9. The lower box according to claim 2, wherein, The protruding part (33) comprises a second protrusion (332), a second side of the heat-exchange plate (10) having a connecting protrusion (113) corresponding to the second protrusion (332), the second protrusion (332) abutting against the connecting protrusion (113), the second protrusion (332) being provided with a connecting piece (40) penetrating therethrough, the connecting piece (40) fixedly connecting the second protrusion (332) and the connecting protrusion (113) so as to clamp and fix the frame (20) by the heat-exchange plate (10) and the support plate (30).

10. The lower tank of claim 9, wherein, a plurality of the second protrusions (332) and the connecting protrusions (113) are provided, and each of the second protrusions (332) corresponds to one of the connecting protrusions (113).

11. The lower tank of claim 10, wherein, the second protrusions (332) are provided in groups, and the second protrusions (332) in the same group are spaced apart in the third direction.

12. The lower tank of claim 11, wherein, a plurality of the support plates (30) are provided, and each of the support plates (30) is arranged along the third direction, and all of the support plates (30) are spaced apart along the second direction, and the second protrusions (332) on all of the support plates (30) are arranged one-to-one with all of the connecting protrusions (113).

13. The drop box of claim 9, wherein, the heat exchange plate (10) comprises: a heat conduction plate (11), the heat exchange surface (111) is located on the heat conduction plate (11), and the connecting protrusion (113) is located on the side of the heat conduction plate (11) away from the heat exchange surface (111); a flow channel plate (12) is buckled with the side of the heat conduction plate (11) away from the heat exchange surface (111), the flow channel plate (12) is provided with a avoiding port (121) corresponding to the connecting protrusion (113), and the connecting protrusion (113) is arranged in the avoiding port (121).

14. The lower tank of claim 13, wherein, a first groove (114) is formed on the heat exchange surface (111) at a position corresponding to the connecting protrusion (113).

15. The lower tank of claim 2, wherein, the side of the support plate (30) facing the heat exchange plate (10) is provided with a reinforcing rib (32) along the third direction; a plurality of the protruding portions (33) are spaced apart on the reinforcing rib (32) in the third direction, and the avoiding grooves (34) are formed between adjacent protruding portions (33) in the second direction; the heat exchange plate (10) has a first refrigerant flow channel arranged along the second direction, and the outer wall of the first refrigerant flow channel forms a protruding structure (124) on the second side of the heat exchange plate (10), the protruding structure (124) is arranged in the avoiding groove (34), and the protruding structure (124) and the inner wall of the avoiding groove (34) are in clearance fit.

16. The lower tank of claim 15, wherein, the protruding portion (33) comprises: a plurality of third protrusions (333), and the avoiding groove (34) is formed between adjacent two third protrusions (333); a plurality of the first refrigerant flow channels are spaced apart in the third direction, and the outer wall of each of the first refrigerant flow channels corresponds to form one of the protruding structures (124) on the second side of the heat exchange plate (10), and a second groove (125) is formed between adjacent two protruding structures (124); Each of the third protrusions (333) corresponds to one of the second grooves (125), and each of the third protrusions (333) abuts in the corresponding second groove (125).

17. The lower box according to claim 16, wherein The reinforcing ribs (32) are multiple, and the reinforcing ribs (32) are spaced apart along the second direction. Each of the reinforcing ribs (32) is provided with multiple protruding portions (33), and the protruding portions (33) on different reinforcing ribs (32) correspond to each other in the second direction.

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