Frame and cast beam structure optimization method

Abstract

The application discloses a frame and a casting beam structure optimization method, and belongs to the technical field of electric vehicles. The frame comprises a placing frame and a plurality of frame bodies. The plurality of frame bodies are arranged at intervals, and the placing frame is connected between two adjacent frame bodies. The inner side of the placing frame is formed with a plurality of placing spaces for placing battery packs. The two ends of the placing frame extend to the outer side of the frame body, so that part of the structure of the placing space is located on the outer side of the frame body. The length of the part of the placing frame extending to the outer side of the frame body is adjustable. The frame can install battery packs with large volumes, and can install a plurality of battery packs with different volumes, has good versatility, and is beneficial to solving the problem of the endurance mileage of the electric vehicle.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and in particular to a method for optimizing the frame and cast crossbeam structure. Background Technology

[0002] In pure electric heavy-duty trucks, the more battery packs there are, the longer the driving range. Therefore, the layout of the battery packs in pure electric heavy-duty trucks has become one of the effective measures to solve the driving range problem. The battery packs are mounted on the chassis, and each battery pack has a different size.

[0003] like Figure 1 As shown, the current vehicle frame has a ladder-shaped structure, consisting of two parallel longitudinal beams 1' and several cross beams 2'. Since other parts such as suspension need to be installed on the frame and the wheel track needs to be considered, the width between the two longitudinal beams 1' is usually a fixed value. However, due to the small width between the two longitudinal beams 1', it is difficult to arrange a large battery pack 3' between the two longitudinal beams 1', which is not conducive to solving the problem of vehicle range.

[0004] To solve the above problems, such as Figure 1 As shown, the battery pack 3' is usually mounted on the outside of the longitudinal beam 1'. However, the space outside the longitudinal beam 1' is very limited, which is not conducive to installing a larger battery pack 3'. In addition, the battery pack 3' on the outside of the longitudinal beam 1' will affect the aesthetics of the frame. Moreover, the longitudinal beam 1' needs to have high rigidity and strength, which leads to a high manufacturing cost for the longitudinal beam 1'.

[0005] To address the above issues, there is an urgent need for optimization methods for the chassis and cast beam structures. Summary of the Invention

[0006] One objective of this invention is to provide a vehicle frame that can mount a large battery pack and multiple battery packs of different sizes, thus offering good versatility.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] The frame includes:

[0009] The vehicle frame body consists of multiple segments, which are spaced apart.

[0010] The placement frame is connected between two adjacent segments of the vehicle frame body. The inner side of the placement frame has multiple placement spaces for placing battery packs, and both ends of the placement frame extend outwards from the vehicle frame body so that a portion of the placement space is located on the outside of the vehicle frame body. The length of the portion of the placement frame extending outwards from the vehicle frame body is adjustable.

[0011] Furthermore, the frame body includes two parallel first longitudinal beams, and the placement frame includes:

[0012] A connecting beam is disposed between the two first longitudinal beams, and both ends of the connecting beam extend outward from the first longitudinal beams respectively. The length of the connecting beam is adjustable.

[0013] The second longitudinal beam is arranged parallel to the first longitudinal beam and connected between two adjacent connecting crossbeams;

[0014] An outer frame is connected between two adjacent connecting beams and extends outward from the first longitudinal beam. The size of the outer frame is adjustable. The second longitudinal beam is disposed inside the outer frame so as to divide the interior of the outer frame into multiple placement spaces.

[0015] Furthermore, the connecting beam includes:

[0016] A cast crossbeam, with the second longitudinal beam connected to the cast crossbeam, and the two ends of the cast crossbeam respectively connected to the two first longitudinal beams;

[0017] The two ends of the cast crossbeam are respectively connected to the extension arm, which is located outside the first longitudinal beam and the length of the extension arm is adjustable.

[0018] Furthermore, the cast crossbeam was obtained using topology optimization analysis.

[0019] Furthermore, the cast crossbeam comprises:

[0020] The main body of the crossbeam has a central block around it, the second longitudinal beam is connected to the central block, and connecting plates are respectively provided at both ends of the main body of the crossbeam, the connecting plates being used to connect with the first longitudinal beam.

[0021] Furthermore, the intermediate block is provided with transverse ribs, which extend along the length of the main body of the beam;

[0022] The two ends of the main body of the crossbeam are respectively provided with arc-shaped ribs. The arc-shaped ribs are located on a portion of the outer periphery of the main body of the crossbeam, and one end of the arc-shaped ribs is connected to the side of the connecting plate near the middle block, and the other end of the arc-shaped ribs is connected to the main body of the crossbeam.

[0023] Furthermore, the outer frame includes:

[0024] Two opposing first frames are arranged parallel to the second longitudinal beam and located outside the first longitudinal beam. The two ends of the first frames are respectively connected to the two opposing extension arms.

[0025] Two opposing second frames are positioned above the connecting crossbeam, with each end of the second frame connected to one of the first frames.

[0026] The intermediate frame is located above the second longitudinal beam, and its two ends are respectively connected to the two second frames.

[0027] Furthermore, the inner wall surface of the placement space is provided with multiple hanging layers at intervals, and each hanging layer is used to hang one of the battery packs;

[0028] The second longitudinal beam, the intermediate frame, and the inner side of the first frame are each provided with a number of hanging plates, and the multiple hanging plates located on the same horizontal plane form the hanging layer.

[0029] Furthermore, reinforcing plates are connected between the second frame and the extension arm, and between the intermediate frame and the main beam.

[0030] Another objective of this invention is to propose a method for optimizing the structure of cast beams, so as to obtain cast beams that meet the strength requirements under various extreme stress conditions while minimizing mass.

[0031] To achieve this objective, the present invention adopts the following technical solution:

[0032] A method for optimizing the structure of a cast crossbeam, based on the vehicle frame described above, is used to perform topology optimization on the cast crossbeams of the frame, and includes the following steps:

[0033] S1: Develop a topology optimization space model for the cast beam;

[0034] S2: Set the limit stress condition of the frame under full vehicle load;

[0035] S3: Topology optimization analysis, taking the maximum stress that the cast beam can withstand under the extreme stress condition as the constraint condition, and taking the minimization of the mass of the cast beam as the optimization objective, to perform topology optimization analysis on the topology optimization space model;

[0036] S4: Obtain the cast beam under topology optimization and perform strength verification.

[0037] The beneficial effects of this invention are as follows:

[0038] By arranging multiple frame segments at intervals and connecting placement frames between adjacent segments, multiple placement spaces for battery packs are formed inside the placement frames. Simultaneously, the two ends of the placement frames extend outwards from the frame body, allowing portions of the formed placement spaces to be located on the outer side of the frame body. This increases the usable space for installing battery packs either inside or outside the frame body. Connecting the inner and outer spaces of the frame body to create placement spaces for battery packs further increases the usable space for battery packs, enabling the installation of larger or even larger battery packs within these spaces, which helps address issues related to vehicle range. This addresses several issues; moreover, placing the battery pack within the mounting space is more aesthetically pleasing than directly mounting it on the outside of the frame; furthermore, since the battery pack is not directly mounted on the first longitudinal beam of the frame, the rigidity and strength requirements of the first longitudinal beam are reduced, resulting in lower manufacturing costs; simultaneously, the length of the portion of the mounting frame extending outwards from the frame is adjustable, allowing the size of the mounting frame to be adjusted according to the specific volume of the battery pack, ensuring that the size of the resulting mounting space matches the size of the battery pack. This allows for the placement of various battery packs of different sizes within the mounting space, improving versatility and applicability.

[0039] The casting crossbeam structure optimization method of the present invention can perform topology optimization on the casting crossbeam, the main stress component in the frame, and take the maximum stress of the casting crossbeam under extreme stress conditions as a constraint condition and the minimization of the mass of the casting crossbeam as the optimization objective. In this way, a casting crossbeam that meets the strength requirements and minimizes the mass can be obtained, which is beneficial to the lightweight design of the casting crossbeam and the entire frame, making the frame lighter. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the battery pack mounting structure on the vehicle frame in the prior art;

[0041] Figure 2 This is a schematic diagram of the frame structure provided by the present invention;

[0042] Figure 3 This is a top view of the vehicle frame (containing the battery pack) provided by the present invention;

[0043] Figure 4 This is a schematic diagram of the placement frame provided by the present invention;

[0044] Figure 5 This is a schematic diagram of the connection structure between the connecting crossbeam and the first longitudinal beam and the second longitudinal beam provided by the present invention;

[0045] Figure 6 This is a schematic diagram of the connecting beam provided by the present invention;

[0046] Figure 7 This is a schematic diagram of the structure of the cast crossbeam provided by the present invention;

[0047] Figure 8 This is a flowchart illustrating the method for optimizing the cast beam structure provided by this invention.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1'-Longitudinal beam; 2'-Crossbeam; 3'-Battery pack;

[0050] 1-Chassis body; 11-First longitudinal beam; 12-Intermediate crossbeam;

[0051] 2-Placement frame; 21-Placement space; 22-Connecting beam; 221-Cast beam; 2211-Bridge body; 2212-Intermediate block; 2213-Web plate; 2214-Connecting plate; 2215-Transverse rib; 2216-Arc-shaped rib; 222-Extension arm; 23-Second longitudinal beam; 24-Outer frame; 241-First frame; 242-Second frame; 243-Intermediate frame; 244-Reinforcing plate; 245-Hanging plate;

[0052] 3-Battery pack. Detailed Implementation

[0053] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0054] Any feature disclosed in this specification, unless specifically stated otherwise, may be replaced by other equivalent or similar features. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features. Throughout this specification, the same reference numerals indicate the same elements.

[0055] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0056] Example 1

[0057] This embodiment proposes a chassis and a vehicle including the chassis. The chassis can accommodate multiple, relatively large battery packs, thereby effectively addressing the vehicle's range issue. In this embodiment, the vehicle is specifically a pure electric heavy-duty truck; however, the specific vehicle is not limited to any vehicle using battery packs.

[0058] Specifically, such as Figure 2 and Figure 3As shown, the frame includes a placement frame 2 and multiple frame body segments 1; wherein, the multiple frame body segments 1 are spaced apart, and the edges of each frame body segment 1 are located on the same straight line; a placement frame 2 is connected between two adjacent frame body segments 1, and multiple placement spaces 21 for placing battery packs 3 are formed on the inner side of the placement frame 2, and both ends of the placement frame 2 extend outwards from the frame body 1, so that part of the structure of the placement space 21 can be located on the outer side of the frame body 1, and the length of the part of the placement frame 2 extending outwards from the frame body 1 is adjustable.

[0059] The frame in this embodiment changes the specific structure of the frame compared to the prior art. By placing part of the placement space 21 inside the frame 2 on the outside of the frame body 1, the usable space for installing the battery pack 3 on the inside or outside of the frame body 1 can be increased. The spaces inside and outside of the frame body 1 are connected to form the placement space 21 for installing the battery pack 3, increasing the usable space for the battery pack 3. This allows for the installation of larger or larger battery packs 3 within the placement space 21, which helps solve the problem of vehicle range. Furthermore, compared to directly hanging the battery pack 3 on the outside of the frame body 1, placing the battery pack 3 in the placement space 21 is more aesthetically pleasing. Moreover, since the battery pack 3 is not directly hung on the first longitudinal beam 11 of the frame body 1, the rigidity and strength requirements of the first longitudinal beam 11 can be reduced, thus lowering the manufacturing cost of the first longitudinal beam 11.

[0060] Meanwhile, by making the length of the portion of the placement frame 2 extending outward from the frame body 1 adjustable, the size of the placement frame 2 can be adjusted according to the specific volume of the battery pack 3, so that the size of the formed placement space 21 can match the size of the battery pack 3, thereby enabling the placement space 21 to hold various battery packs 3 of different sizes, thus improving versatility and applicability.

[0061] Furthermore, such as Figure 2 and Figure 3 As shown, each frame body 1 includes two parallel first longitudinal beams 11 and several intermediate cross beams 12. Each intermediate cross beam 12 is spaced between the two first longitudinal beams 11. The intermediate cross beams 12 are perpendicular to the first longitudinal beams 11. Due to the installation requirements inside the vehicle, the width between the two first longitudinal beams 11 is a fixed value.

[0062] Specifically, such as Figures 2 to 4As shown, the placement frame 2 includes a connecting crossbeam 22, a second longitudinal beam 23, and an outer frame 24. The connecting crossbeam 22 is disposed between two first longitudinal beams 11, and both ends of the connecting crossbeam 22 extend outward from the first longitudinal beams 11 respectively. The length of the connecting crossbeam 22 is adjustable. The second longitudinal beam 23 is disposed parallel to the first longitudinal beams 11 and is located between the two first longitudinal beams 11. The second longitudinal beam 23 is connected between two adjacent connecting crossbeams 22. The outer frame 24 is connected between two adjacent connecting crossbeams 22 and extends outward from the first longitudinal beams 11. The size of the outer frame 24 is adjustable. The second longitudinal beam 23 is disposed inside the outer frame 24 so that the interior of the outer frame 24 can be divided into multiple placement spaces 21 by the second longitudinal beam 23.

[0063] Specifically, such as Figure 5 and Figure 6 As shown, the connecting beam 22 includes a cast beam 221 and an extension arm 222; wherein, the end of the second longitudinal beam 23 is connected to the cast beam 221, the two ends of the cast beam 221 are respectively connected to the two first longitudinal beams 11, and the cast beam 221 is parallel to the intermediate beam 12; an extension arm 222 is connected to the two ends of the cast beam 221, the extension arm 222 is located outside the first longitudinal beam 11, and the length of the extension arm 222 is adjustable.

[0064] By making the size of the outer frame 24 adjustable and the length of the extension arm 222 adjustable, the length of the portion of the entire placement frame 2 extending outward toward the first longitudinal beam 11 of the frame body 1 can be adjusted. That is to say, outer frames 24 of different sizes and extension arms 222 of different lengths can be set, thereby making the size of the placement space 21 inside the placement frame 2 adjustable. This allows for the placement of various battery packs 3 of different sizes to be placed in the placement space 21, thereby increasing the versatility and applicability of the frame.

[0065] Since the structure of the frame in this embodiment is different from that of the frame in the prior art, it is necessary to verify the strength of the frame. During the strength verification process by performing finite element strength analysis on the frame, it was shown that the cast crossbeam 221 in the frame is the core component of the frame. Therefore, the cast crossbeam 221 was obtained by topology optimization analysis.

[0066] The casting crossbeam 221 is obtained by performing topology optimization analysis, which can remove unnecessary materials from the casting crossbeam 221 and ensure that the mass of the obtained casting crossbeam 221 is minimized, which is beneficial to the lightweighting of the casting crossbeam 221 and the entire frame. At the same time, it can ensure the service strength of the casting crossbeam 221 and the frame under various extreme working conditions, so as to ensure the stress that the casting crossbeam 221 can withstand under full load and various extreme stress conditions.

[0067] Furthermore, such as Figure 7 As shown, the cast crossbeam 221 includes a crossbeam body 2211, an intermediate block 2212 circumferentially arranged on the crossbeam body 2211, a web plate 2213 arranged on the intermediate block 2212, and a second longitudinal beam 23 connected to the web plate 2213 of the intermediate block 2212; and connecting plates 2214 are respectively arranged at both ends of the crossbeam body 2211, the connecting plates 2214 being used to connect with the first longitudinal beam 11. In this embodiment, the crossbeam body 2211 is a cylindrical structure.

[0068] Specifically, such as Figure 7 As shown, transverse ribs 2215 are provided on the intermediate block 2212. The transverse ribs 2215 extend along the length of the main body of the crossbeam 2211, that is, the transverse ribs 2215 are perpendicular to the first longitudinal beam 11, so as to improve the torsional stiffness of the cast crossbeam 221 and the entire frame. There are multiple transverse ribs 2215, which are parallel and spaced apart.

[0069] Furthermore, such as Figure 7 As shown, arc-shaped ribs 2216 are respectively provided at both ends of the main body of the crossbeam 2211. The arc-shaped ribs 2216 are located on part of the outer periphery of the main body of the crossbeam 2211, that is, there is a gap between the arc-shaped ribs 2216 and the main body of the crossbeam 2211. One end of the arc-shaped ribs 2216 is connected to the side of the connecting plate 2214 near the middle block 2212, and the other end of the arc-shaped ribs 2216 is connected to the main body of the crossbeam 2211.

[0070] By setting arc-shaped ribs 2216, the local stress at the end of the main beam 2211 can be dispersed, avoiding the problem of local stress concentration at the end of the main beam 2211, thereby preventing cracks or even breakage of the main beam 2211 and better protecting the main beam 2211.

[0071] Specifically, such as Figures 2 to 4 As shown, the outer frame 24 includes two opposing first frames 241, two opposing second frames 242, and an intermediate frame 243; wherein, the first frames 241 are arranged parallel to the second longitudinal beam 23 and located outside the first longitudinal beam 11, and the two ends of the first frames 241 are respectively connected to the ends of the two opposing extension arms 222; the second frames 242 are located above the connecting beam 22, and the two ends of the second frames 242 are respectively connected to the ends of the two first frames 241; the intermediate frame 243 is located above the second longitudinal beam 23, and the two ends of the intermediate frame 243 are respectively connected to the two second frames 242.

[0072] Specifically, such as Figure 4As shown, two first frames 241 and two second frames 242 are arranged to form the outer structure of the outer frame 24. The inner side of the first frame 241, the inner side of the partial structure of the two oppositely arranged second frames 242, the inner side of the partial structure of the two oppositely arranged connecting beams 22, the second longitudinal beam 23 and the intermediate frame 243 are arranged to form the aforementioned placement space 21.

[0073] Furthermore, multiple hanging layers are formed at intervals on the inner wall of each placement space 21, with each hanging layer used to hang one battery pack 3, thereby enabling multiple battery packs 3 to be hung in layers within the placement space 21, and thus enabling a greater number of battery packs 3 to be installed on the vehicle frame.

[0074] Specifically, such as Figure 4 As shown, several hanging plates 245 are respectively provided on the inner sides of the second longitudinal beam 23, the intermediate frame 243, and the first frame 241. The multiple hanging plates 245 located on the same horizontal plane form a hanging layer, and the battery pack 3 is directly hung on each hanging plate 245. Alternatively, the hanging plates 245 can be provided between the intermediate frame 243 and the second longitudinal beam 23, or on the inner side of the second frame 242. The specific location of the hanging plates 245 is not limited, as long as it can ensure that the battery pack 3 is stably hung on the hanging plates 245.

[0075] Furthermore, such as Figure 4 As shown, reinforcing plates 244 are connected between the second frame 242 and the extension arm 222, and between the intermediate frame 243 and the crossbeam body 2211, respectively, to increase the connection stability and thus ensure the reliability of the entire placement frame 2.

[0076] Example 2

[0077] This embodiment proposes a method for optimizing the structure of a cast crossbeam. Based on the frame in Embodiment 1 above, this method is used to perform topology optimization on the cast crossbeam 221 placed in the frame 2 so that the cast crossbeam 221 minimizes its mass while meeting the strength requirements.

[0078] Specifically, such as Figure 8As shown, the optimization method for the cast crossbeam structure includes the following steps: S1: Develop a topology optimization space model for the cast crossbeam 221. Based on the process assembly requirements of the cast crossbeam 221, determine the maximum arrangement space for the cast crossbeam 221. That is, the topology optimization space model needs to meet the maximum installation space requirement of the cast crossbeam 221 within the vehicle frame; S2: Set the ultimate stress condition of the vehicle frame under full vehicle load; S3: Perform topology optimization analysis. Using the maximum stress of the cast crossbeam 221 under the ultimate stress condition as a constraint, and minimizing the mass of the cast crossbeam 221 as the optimization objective, perform topology optimization analysis on the topology optimization space model; S4: Obtain the cast crossbeam 221 under topology optimization, and perform strength verification on the obtained cast crossbeam 221 to ensure that the cast crossbeam 221 meets the requirements of strength and mass minimization.

[0079] Specifically, step S2 includes four extreme stress conditions: Z-axis impact on the frame, extreme cornering on the frame, extreme braking on the frame, and diagonal torsion on the frame. The cast crossbeam 221 and the frame must meet the strength requirements under these four extreme stress conditions. Specifically, the Z-axis... Figure 2 As indicated by the middle arrow Z.

[0080] Furthermore, when the chassis experiences a Z-axis impact, a Z-axis acceleration of -2.5g is required; when the chassis undergoes extreme cornering, a Y-axis acceleration of 0.5g and a Z-axis acceleration of -1g are required; when the chassis undergoes extreme braking, an X-axis acceleration of -0.8g and a Z-axis acceleration of -1g are required; and when the chassis undergoes diagonal torsion, the left front wheel and right rear wheel need to be raised by 150mm simultaneously. The X, Y, and Z axes are mutually perpendicular. Since topology optimization is a common optimization method in existing technologies, its specific working principle will not be elaborated upon here.

[0081] The specific working process of the casting beam structure optimization method in this embodiment is as follows:

[0082] First, based on the process assembly requirements of the cast crossbeam 221, the maximum arrangement space of the cast crossbeam 221 is determined to form a topology-optimized space model. Then, under the condition of the vehicle being fully loaded, the cast crossbeam 221 and the frame are set to be subjected to four extreme stress conditions: Z-axis impact, extreme turning, extreme braking, and diagonal torsion.

[0083] Then, the maximum stress that the cast beam 221 can withstand under the four extreme stress conditions is used as a constraint condition, and the minimization of the mass of the cast beam 221 is used as the optimization objective. Topology optimization analysis is then performed on the topology optimization space model to remove unnecessary materials from the topology optimization space model.

[0084] Finally, based on the results of the topology optimization analysis, and according to the optimal material space layout of the cast beam 221 obtained from the topology optimization analysis, the design of the cast beam 221 was completed, and the strength of the designed cast beam 221 was further verified to ensure that the cast beam 221 can meet the strength requirements under various working conditions.

[0085] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A frame, characterized in that, include: The frame body (1) consists of multiple segments, which are spaced apart. The placement frame (2) is connected between two adjacent segments of the frame body (1). The inner side of the placement frame (2) forms a plurality of placement spaces (21) for placing the battery pack (3). Both ends of the placement frame (2) extend outward from the frame body (1) so that part of the structure of the placement space (21) is located on the outside of the frame body (1). The length of the part of the placement frame (2) extending outward from the frame body (1) is adjustable. The frame body (1) includes two parallel first longitudinal beams (11), and the placement frame (2) includes: A connecting beam (22) is provided between two first longitudinal beams (11), and both ends of the connecting beam (22) extend outward from the first longitudinal beams (11), and the length of the connecting beam (22) is adjustable; The second longitudinal beam (23) is arranged parallel to the first longitudinal beam (11) and connected between two adjacent connecting beams (22); The outer frame (24) is connected between two adjacent connecting beams (22) and extends outward from the first longitudinal beam (11). The size of the outer frame (24) is adjustable. The second longitudinal beam (23) is disposed inside the outer frame (24) so ​​as to divide the interior of the outer frame (24) into multiple placement spaces (21). The connecting beam (22) includes: A cast crossbeam (221) is provided, and a second longitudinal beam (23) is connected to the cast crossbeam (221). The two ends of the cast crossbeam (221) are respectively connected to two first longitudinal beams (11). The two ends of the cast crossbeam (221) are respectively connected to the extension arm (222), the extension arm (222) is located outside the first longitudinal beam (11), and the length of the extension arm (222) is adjustable; The cast crossbeam (221) includes: A crossbeam body (2211) is provided with an intermediate block (2212) on the crossbeam body (2211). A web plate (2213) is provided on the intermediate block (2212). The second longitudinal beam (23) is connected to the web plate (2213) of the intermediate block (2212). A connecting plate (2214) is provided at both ends of the crossbeam body (2211). The connecting plate (2214) is used to connect with the first longitudinal beam (11).

2. The frame as described in claim 1, characterized in that, The cast crossbeam (221) was obtained through topology optimization analysis.

3. The frame as described in claim 1, characterized in that, The intermediate block (2212) is provided with transverse ribs (2215), which extend along the length direction of the main beam (2211); The two ends of the main body of the crossbeam (2211) are respectively provided with arc-shaped ribs (2216). The arc-shaped ribs (2216) are located on a part of the outer periphery of the main body of the crossbeam (2211), and one end of the arc-shaped ribs (2216) is connected to the side of the connecting plate (2214) near the middle block (2212), and the other end of the arc-shaped ribs (2216) is connected to the main body of the crossbeam (2211).

4. The frame as described in claim 3, characterized in that, The outer frame (24) includes: Two opposing first frames (241) are arranged parallel to the second longitudinal beam (23) and located outside the first longitudinal beam (11). The two ends of the first frames (241) are respectively connected to the two opposing extension arms (222). Two opposing second frames (242) are located above the connecting beam (22), and both ends of the second frames (242) are respectively connected to the two first frames (241). The intermediate frame (243) is located above the second longitudinal beam (23), and the two ends of the intermediate frame (243) are respectively connected to the two second frames (242).

5. The frame as described in claim 4, characterized in that, The inner wall of the placement space (21) is provided with multiple hanging layers, one of which is used to hang one of the battery packs (3). The inner sides of the second longitudinal beam (23), the intermediate frame (243), and the first frame (241) are respectively provided with a number of hanging plates (245), and the multiple hanging plates (245) located on the same horizontal plane form the hanging layer.

6. The frame as described in claim 4, characterized in that, A reinforcing plate (244) is connected between the second frame (242) and the extension arm (222), and between the intermediate frame (243) and the crossbeam body (2211).

7. A method for optimizing the structure of cast beams, characterized in that, Based on the frame as described in any one of claims 1-6, the casting crossbeam structure optimization method is used to perform topology optimization on the casting crossbeam (221) of the placement frame (2), including the following steps: S1: Develop a topology-optimized spatial model for the cast beam (221); S2: Set the limit stress condition of the frame under full vehicle load; S3: Topology optimization analysis, taking the maximum stress of the cast beam (221) under the extreme stress condition as the constraint condition, and taking the minimization of the mass of the cast beam (221) as the optimization objective, the topology optimization space model is subjected to topology optimization analysis. S4: Obtain the cast beam (221) under topology optimization and perform strength verification.

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