Modularized lower vehicle body structure, vehicle and assembling method thereof

Abstract

The invention discloses a modularized lower vehicle body structure, a vehicle and an assembling method of the vehicle, and belongs to the technical field of automobile manufacturing. The modularized lower vehicle body structure comprises an integrated lower vehicle body assembly, wherein an installation space is defined by an integrated cabin, an integrated rear floor, a left doorsill and a right doorsill; and the integrated CTC battery pack frame body is provided with a first connecting structure, and the lower vehicle body assembly is provided with a corresponding second connecting structure. The first connecting structure comprises a front fixing hole, a rear fixing hole and a lateral locking boss. The second connecting structure comprises a front-back connecting plug and a lateral clamping hole. The lateral locking boss penetrates through a lateral clamping hole in the doorsill and then is clamped with a lateral clamping groove in a battery fixing plate arranged on the inner side of the doorsill. Scattered bolt connecting points are simplified into an integrated rapid clamping structure, the assembling efficiency and the size consistency of the connecting points are remarkably improved, and therefore the sealing performance is improved; meanwhile, point connection is changed into line connection, and the rigidity and the side impact performance of the vehicle body are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile manufacturing, and in particular to a modular lower vehicle body structure, a vehicle and an assembly method thereof. Background Art

[0002] With the rapid development of new energy vehicle technology, driving range and interior space have become core consumer concerns and directly impact market competitiveness. To improve the energy density and space utilization of battery systems, CTC (Cell to Chassis) technology has emerged as a key trend in current vehicle body structural design. The core concept of CTC technology is to eliminate the traditional independent packaging of battery packs and integrate battery cells or modules directly into the vehicle chassis, making the battery system an integral part of the vehicle's load-bearing structure. This highly integrated design not only eliminates redundant structural components (such as the battery box and crossbeams), providing valuable space for the placement of more battery cells, thereby effectively improving vehicle range, but also enhances the overall structural performance of the vehicle body through the inherent rigidity of the battery.

[0003] However, in the process of implementing existing CTC solutions, there are generally a series of severe technical challenges. Taking some mainstream solutions in the industry as an example (such as Figure 1 As shown in the figure, the seats are usually mounted directly on the battery cover, and the entire battery assembly is then connected to the vehicle body (such as the door sills, longitudinal beams, and cross beams) with a large number of bolts. This solution has the following obvious problems and disadvantages:

[0004] Too many installation points and low assembly efficiency: To ensure the mechanical reliability of the connection and the critical sealing performance, a large number of connection points are required between the battery pack and the vehicle body. As shown in Table 1, the number of battery pack installation points in competing models is generally over 30, and some even approach 40. On the final assembly line, a considerable amount of time is required to locate, tighten, and ensure that the torque of these bolts meets the requirements one by one. This results in an extremely complex assembly process and a long production cycle, which seriously restricts the production efficiency of the entire vehicle and forms a production capacity bottleneck.

[0005] Dimensional consistency is difficult to ensure: The numerous dispersed bolt connection points place extremely high demands on the manufacturing precision of the vehicle body and battery pack. The cumulative tolerances between the vehicle body holes and the battery pack mounting points are difficult to control. Any slight deviation can lead to excessive installation stress, misaligned bolts, or uneven final clamping force, which in turn affects the battery pack's sealing performance and long-term structural reliability.

[0006] Sealing issues are prominent: As high-voltage components, battery packs must achieve IP67 or higher sealing levels to ensure safety. Distributed bolted connection points require reliable sealing and clamping around each point, which places extremely high demands on sealant / gasket design, coating processes, and precise control of bolt preload. Insufficient or uneven clamping force at any connection point can lead to seal failure, posing a serious safety hazard.

[0007] Unsatisfactory structural performance transfer: While the CTC solution inherently improves rigidity, the discrete point connections create a discontinuous load transfer path when transmitting loads (especially in side impacts), which can easily lead to stress concentration. This connection method is limited in its ability to evenly transfer and distribute side impact forces throughout the vehicle body structure, failing to maximize its contribution to improving the overall torsional rigidity and side impact safety performance of the BIW.

[0008] Therefore, a new CTC integration solution is urgently needed to fundamentally solve the technical problems of excessive installation points, low assembly efficiency, and difficulty in ensuring dimensional consistency and sealing in existing technologies. At the same time, it can further optimize the structural performance of the vehicle body and achieve truly efficient, highly reliable, and high-performance CTC body integration. Summary of the Invention

[0009] The purpose of the present invention is to provide a modular lower body structure, body and assembly method thereof, aiming to solve the technical problems existing in the existing CTC technology, such as too many battery packaging points, low installation efficiency, difficulty in ensuring dimensional consistency, poor sealing and the need to improve the body rigidity.

[0010] To achieve the above objectives, the present invention provides a modular lower vehicle body structure in a first aspect, comprising:

[0011] An integrated lower body assembly, wherein the integrated lower body assembly is composed of an integrated cabin, an integrated rear floor, and left and right door sills respectively connected between the integrated cabin and the integrated rear floor to form an installation space for accommodating a battery pack; and

[0012] an integrated CTC battery pack frame, the integrated CTC battery pack frame being suitable for installation in the installation space;

[0013] Among them, the integrated CTC battery pack frame is provided with multiple first connection structures, and the integrated lower body assembly is provided with multiple second connection structures corresponding to the first connection structures; the integrated CTC battery pack frame is installed on the integrated lower body assembly in a quick snap-on manner through the cooperation of the first connection structure and the second connection structure.

[0014] In some optional embodiments, the integrated CTC battery pack frame includes an integrated die-cast lower frame and an upper shell sealed to the lower frame. This structure takes into account strength, lightness and sealing.

[0015] In some optional embodiments, the first connection structure includes: at least one front fixing hole located at the front end of the integrated CTC battery pack frame; at least one rear fixing hole located at the rear end of the integrated CTC battery pack frame; and multiple lateral locking bosses located on the left and right sides of the integrated CTC battery pack frame. This distributed connection structure design can securely position and lock the battery pack frame in three dimensions.

[0016] In some optional embodiments, the second connection structure includes: at least one front plug connector provided on the integrated cabin and corresponding to the front fixing hole; at least one rear plug connector provided on the integrated rear floor and corresponding to the rear fixing hole; and a plurality of lateral latch holes provided on the inner sides of the left and right door sills, the lateral latch holes corresponding one-to-one with the lateral locking bosses. The combination of plug-in and latching enables self-guiding and quick locking during installation. At the same time, the lateral latch holes not only serve to position the door sill and the integrated CTC battery pack frame, but also latch them together.

[0017] In some optional embodiments, the modular lower body structure further includes a left battery mounting plate and a right battery mounting plate; the left battery mounting plate is disposed on the inner side of the left door sill, and the right battery mounting plate is disposed on the inner side of the right door sill; the left and right battery mounting plates are provided with lateral slots corresponding to the lateral locking bosses. The lateral locking bosses extend through the lateral mounting holes and lateral slots, respectively. By adding a battery mounting plate and engaging the lateral slots with the lateral locking bosses, the dispersed connection points are integrated into a single component, significantly improving dimensional consistency.

[0018] In some optional embodiments, the lateral locking boss includes an open groove provided on the outer wall; the lateral slot includes a through hole for the lateral locking boss to pass through, and a limiting slot connected to the through hole; after the lateral locking boss passes through the through hole, the battery fixing plate on the inner side of the door sill is pushed so that the limiting slot is snapped into the open groove, thereby realizing rapid snap connection between the door sill and the integrated CTC battery pack frame.

[0019] In some optional embodiments, the left and right door sills are both aluminum extrusions; the left and right battery mounting plates are bolted or welded to the internal grooves of the aluminum extrusions. The high precision and regular internal structure of the aluminum extrusions provide a stable and reliable mounting base for the battery mounting plates.

[0020] In some optional embodiments, the integrated cabin, integrated rear floor, and left and right side sills are connected using self-pierce riveting (SPR). SPR is a highly efficient cold joining process suitable for joining lightweight materials such as aluminum alloys, ensuring the connection strength and production efficiency of the lower body assembly.

[0021] A second aspect of the present invention provides a vehicle body comprising the modular lower vehicle body structure described in any of the aforementioned solutions.

[0022] A third aspect of the present invention provides a method for assembling a modular lower vehicle body structure, comprising the following steps:

[0023] Preparing an integrated lower vehicle body assembly, the preparation step comprising: connecting the integrated cabin, the integrated rear floor, the left door sill, and the right door sill to enclose a mounting space for accommodating the battery pack;

[0024] Providing an integrated CTC battery pack frame, wherein the integrated CTC battery pack frame is provided with a plurality of first connection structures;

[0025] The integrated CTC battery pack frame is assembled to the integrated lower body assembly, and the assembly step includes: quickly snap-fitting the first connecting structure with the second connecting structure provided on the integrated lower body assembly to fix the integrated CTC battery pack frame in the installation space.

[0026] In some optional embodiments, the step of preparing the integrated lower body assembly is specifically: connecting the integrated cabin and the integrated rear floor to the two ends of the left and right door sills respectively through a self-pierce riveting (SPR) process.

[0027] In some optional embodiments, the step of assembling the integrated CTC battery pack frame to the integrated lower body assembly specifically includes: lifting the integrated CTC battery pack frame from the bottom to the top into the installation space; aligning and snapping the front fixing hole at the front end of the integrated CTC battery pack frame with the front plug connector on the integrated cabin, and aligning and snapping the rear fixing hole at the rear end of the integrated CTC battery pack frame with the rear plug connector on the integrated rear floor; aligning the lateral locking bosses on both sides of the integrated CTC battery pack frame with the lateral snap holes on the inner side of the door sill, and snapping and locking them.

[0028] In some optional embodiments, a battery retaining plate is provided on the inner side of the door sill, and the battery retaining plate has lateral slots corresponding to the lateral locking bosses. The battery retaining plate slides relative to the door sill to achieve synchronous tightening or loosening of the multiple lateral locking bosses and the multiple lateral slots. This synchronous operation greatly simplifies assembly and improves efficiency.

[0029] In some optional embodiments, before assembling the integrated CTC battery pack frame to the integrated lower vehicle body assembly, the method further includes applying a circle of sealing foam around the upper surface of the integrated CTC battery pack frame.

[0030] The beneficial effects of the present invention are:

[0031] 1. High efficiency and fewer connections: This invention simplifies the original 20 to 30 bolt connection points into a handful of quick-connect structures, such as 11 quick-connect points and two sets of slots. The assembly process changes from the tedious process of tightening bolts one by one to the simple steps of hoisting, aligning, and connecting the entire assembly. This significantly shortens assembly time, greatly improves assembly line efficiency, and reduces labor costs.

[0032] 2. High consistency and strong sealing: By integrating multiple side connection points into a single battery mounting plate and precisely mounting the plate on a uniform aluminum door sill profile, the problem of multi-point tolerance accumulation is fundamentally resolved. High dimensional consistency at all lateral connection points ensures a uniform and reliable fit between the battery pack frame and the vehicle body. Combined with the sealing foam, this effectively solves the overall sealing problem of the CTC battery pack, enhancing vehicle safety and reliability.

[0033] 3. High Rigidity and Excellent Performance: The side connections have been transformed from discrete "point connections" to a "line connection" achieved through the battery mounting plate. This continuous connection method more effectively transfers loads, significantly improving the side connection strength and local body stiffness. In a side collision, it better transmits and distributes the impact force to the body frame, optimizing side impact performance. Furthermore, the enhanced lower body structural integrity effectively improves the overall torsional stiffness of the body-in-white.

[0034] 4. Modular Design and Simplified Processes: This invention decomposes the lower body into two modules: an integrated lower body assembly and an integrated CTC battery pack frame. These modules can be preassembled separately and then quickly assembled on the final assembly line. This modular design simplifies production logistics and assembly processes, facilitating flexible production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments disclosed in the present invention, the drawings of the embodiments will be briefly introduced below. These drawings are only used for illustrative purposes and are not intended to limit the scope of protection of the present invention.

[0036] Figure 1 It is a structural schematic diagram of a modular lower vehicle body provided by an embodiment of the present invention.

[0037] Figure 2 It is a structural schematic diagram of the integrated CTC battery pack frame in an embodiment of the present invention.

[0038] Figure 3 yes Figure 2 Enlarged schematic diagram of point A in the middle.

[0039] Figure 4 It is a structural schematic diagram of the integrated lower vehicle body assembly in an embodiment of the invention.

[0040] Figure 5 This is a schematic diagram of the connection structure between the threshold and the battery fixing plate in an embodiment of the present invention.

[0041] Figure 6 yes Figure 5 AA section view in.

[0042] Figure 7 2 is a schematic diagram of a state in which the door sill and the battery fixing plate are clamped together in an embodiment of the present invention.

[0043] Figure 8 2 is a schematic diagram of a state in which the door sill and the battery fixing plate are loosened in an embodiment of the present invention.

[0044] In the figure: 1. Integrated CTC battery pack lower frame; 1-1. Front fixing hole; 1-2. Rear fixing hole; 1-3. Left lateral locking boss; 1-4. Right lateral locking boss; 2. Battery pack upper shell; 3. Integrated CTC battery pack frame; 4. Left door sill; 5. Left battery fixing plate; 6. Left door sill assembly; 7. Right door sill; 8. Right battery fixing plate; 9. Right door sill assembly; 10. Integrated cabin; 10-1. Front plug connector; 11. Integrated rear floor; 11-1. Rear plug connector; 12. Left front connector; 13. Right front connector; 14. Left rear connector; 15. Right rear connector; 16. Integrated lower body assembly; 17. Sealing foam; 18. Opening groove. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] It should be noted that, in the description of the present invention, the terms "upper", "lower", "left", "right", "front", "back", "inside", "outside", "side", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. Unless otherwise expressly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0047] Example 1

[0048] This embodiment provides a modular lower vehicle body structure. Figures 1 to 8 The structure mainly includes two core modules: the integrated lower body assembly 16 and the integrated CTC battery pack frame 3.

[0049] Integrated lower body assembly 16 (such as Figure 4 (as shown) is the pre-assembled main load-bearing structure of the vehicle body bottom. It is enclosed by the integrated cabin 10 (vehicle front structure), the integrated rear floor 11 (vehicle rear structure), the left door sill assembly 6 and the right door sill assembly 9 to form a central installation space, which is used to accommodate the integrated CTC battery pack frame 3. The connection between these main structural parts preferably adopts the SPR (self-piercing riveting) process. For example, the front end of the left door sill assembly 6 is connected to the corresponding part of the integrated cabin 10 through the left front joint 12, and the rear end is connected to the corresponding part of the integrated rear floor 11 through the left rear joint 14. Similarly, the right door sill assembly 9 is connected to the integrated cabin 10 and the integrated rear floor 11 through the right front joint 13 and the right rear joint 15 respectively. The SPR connection ensures connection strength and production efficiency, and is particularly suitable for vehicle bodies made of lightweight materials such as aluminum alloy.

[0050] Integrated CTC battery pack frame 3 (such as Figure 1 and Figure 2 The battery pack (shown in the figure) is the core component that houses the battery cells. It consists primarily of two parts: the integrated CTC battery pack lower frame 1 and the battery pack upper housing 2. The lower frame 1 is preferably formed using a lightweight, high-strength material such as aluminum alloy through an integrated die-casting process, ensuring its structural integrity and dimensional accuracy. The upper housing 2, typically a sheet metal component, overlies the lower frame 1. The two are connected on all sides using reliable connection and sealing methods such as FDS (flow drill screws), forming a sealed battery pack space.

[0051] In order to achieve rapid and precise positioning and firm connection between the integrated CTC battery pack frame 3 and the integrated lower vehicle body assembly 16 , corresponding first and second connecting structures are provided between the two.

[0052] The first connection structure provided on the integrated CTC battery pack frame 3 (specifically, the lower frame 1 thereof) includes:

[0053] Front end: at least one front fixing hole 1-1 (for example, 6, such as Figure 2 as shown), used for positioning and connection with the vehicle head direction.

[0054] Rear end: at least one rear fixing hole 1-2 (e.g. 5, such as Figure 2 as shown), used for positioning and connection with the rear end of the vehicle.

[0055] Left side: multiple (e.g. 9) left side locking bosses 1-3 (e.g. Figure 2 and Figure 3 As shown). These bosses are integrally cast raised structures distributed along the left edge of the lower frame 1. Figure 3 As shown, an opening groove 18 may be provided on the outer wall of each lateral locking boss 1 - 3 for subsequent limiting cooperation with the locking slot.

[0056] Right side: multiple (for example, 9) right side locking bosses 1-4 (the structure is symmetrical to 1-3).

[0057] The second connection structure provided on the integrated lower vehicle body assembly 16 includes:

[0058] Front end (located on the integrated nacelle 10): at least one front plug connector 10-1 (such as Figure 4 As shown, it may be provided with a spring sleeve), the number and position of which correspond to the front fixing hole 1-1.

[0059] Rear end (located on the integrated rear floor 11): at least one rear plug connector 11-1 (similar in structure to 10-1, not clearly marked in all figures, but the principle is the same), the number and position of which correspond to the rear fixing holes 1-2.

[0060] Left side (located inside the left door sill assembly 6): In order to cooperate with the left side locking boss 1-3, a left battery fixing plate 5 is set inside the left door sill assembly 6. The left door sill 4 (the main component of the left door sill assembly 6 is an aluminum extruded profile, such as Figure 5 and Figure 6 The left battery retaining plate 5 is mounted within a recess (e.g., secured by end bolts) on the left battery retaining plate 5. A lateral latching slot is provided on the left battery retaining plate 5, corresponding to each of the left lateral locking bosses 1-3. (The detailed structure of these slots is not fully illustrated in the figure, but their function is to engage with the bosses 1-3 and the open slot 18 to form a latching connection.)

[0061] Right side (located inside the right door sill assembly 9): Symmetrical to the left side, a right battery fixing plate 8 and a corresponding lateral slot are provided to cooperate with the right lateral locking boss 1-4.

[0062] The door sill 4 / 7 features side latch holes (not separately labeled), whose position and dimensions correspond to the side locking bosses. More importantly, the battery mounting plate 5 / 8, mounted on the inside of the door sill, also features side latch slots that correspond one-to-one with the side locking bosses.

[0063] like Figure 7 and Figure 8 As shown, they show the clamping and loosening states of the lateral connection. When the battery pack frame 3 is installed upward, its lateral locking boss 1-3 first passes through the lateral clamping hole on the door sill 4, and then enters the lateral clamping slot on the battery fixing plate 5. The lateral clamping slot consists of a larger through hole and a smaller limiting slot connected to it. After the lateral locking boss 1-3 completely passes through the through hole, the battery fixing plate 5 is driven to perform a slight relative sliding relative to the door sill 4 (for example, pulling and inserting along the length direction of the vehicle), so that the groove wall of the limiting groove is accurately clamped into the open groove 18 of the lateral locking boss 1-3. At this time, the effect as shown in the figure is achieved. Figure 7 In the "clamped" state shown, the battery pack frame is firmly locked on the vehicle body. Sliding the battery fixing plate 5 in the reverse direction can make the limit groove disengage from the opening groove 18, achieving the following Figure 8 The "loose" state shown here makes it easier to disassemble and repair the battery pack.

[0064] In addition, in order to ensure the sealing, a circle of sealing foam 17 (such as Figure 1 shown, schematically illustrated in a battery pack frame assembly).

[0065] This modular lower body structure significantly improves assembly efficiency by reducing the number of connection points from the traditional twenty or thirty bolts to "11 quick-connects + two row connections" (the "row connections" here refer to lateral synchronized connection via the battery mounting plate), as described in the technical briefing. Furthermore, because the lateral connection points are integrated into a single battery mounting plate and uniformly mounted within the precision-extruded door sill profile, dimensional consistency is effectively guaranteed. Combined with the sealing foam, this ensures the sealing performance of the CTC battery pack. More importantly, the lateral "line connection" replaces "point connection," enhancing the continuity and uniformity of load transfer, thereby improving body rigidity and side impact resistance.

[0066] Example 2

[0067] This embodiment provides an assembly method for a modular lower vehicle body structure, which is used to assemble the structure described in Example 1.

[0068] 1. Preparation of the integrated lower body assembly 16:

[0069] a. Provide an integrated cabin 10 and an integrated rear floor 11.

[0070] b. Provide pre-assembled left and right door sill assemblies 6 and 9. Pre-assembly includes connecting the left door sill 4 to the left front connector 12 and the left rear connector 14, and installing the left battery retaining plate 5 with a lateral slot into the inner recess of the left door sill 4 (ensure it is in an operable state, e.g., initially in the released position). Repeat the same procedure for the right side.

[0071] c. Using a process such as SPR, connect the left and right sill assemblies 6 and 9 to the corresponding positions of the integrated engine compartment 10 and the integrated rear floor 11, respectively, to form a complete integrated lower body assembly 16. At this point, the front connector 10-1, rear connector 11-1, and the lateral slots on the inside of the sill are all in place.

[0072] 2. Provide integrated CTC battery pack frame 3:

[0073] a. Connect and seal the battery pack upper shell 2 and the integrated CTC battery pack lower frame 1 by means of FDS or the like to form an integrated CTC battery pack frame 3.

[0074] b. In some embodiments of the present invention, a circle of sealing foam 17 is applied where the upper surface of the vehicle body is in contact with the vehicle body.

[0075] 3. Quick assembly:

[0076] a. The integrated CTC battery pack frame 3 is lifted from below to the installation space of the integrated lower body assembly 16 by a special hoist.

[0077] b. First, align the front and rear directions: insert the front fixing hole 1-1 at the front of the integrated CTC battery pack frame 3 into the front connector 10-1 on the integrated engine compartment 10. Simultaneously or subsequently, insert the rear fixing hole 1-2 at the rear into the rear connector 11-1 on the integrated rear floor 11. This completes the initial longitudinal and partial lateral positioning.

[0078] c. Then, perform the lateral quick-connection: Confirm that the lateral locking bosses 1-3 and 1-4 on both sides are aligned with the slot entrances on the battery mounting plate inside the door sill or the guide holes on the door sill. By operating the mechanism (for example, by simultaneously pushing or pulling the battery mounting plates 5 and 8 on both sides), the lateral slots on the battery mounting plate engage with the corresponding openings of the lateral locking bosses, completing the synchronous locking of all lateral connection points on both sides.

[0079] d. Check that all connection points are firmly in place and assembly is complete.

[0080] This assembly method transforms the originally time-consuming and labor-intensive multi-point bolt tightening operation into modular pre-installation and final rapid alignment and snap-in operations, greatly shortening the operation time on the final assembly line and improving production efficiency.

[0081] Example 3

[0082] This embodiment relates to a vehicle that adopts the modular lower body structure described in Example 1 and is assembled by the method described in Example 2. Due to the adoption of the technical solution of the present invention, the vehicle can achieve significant improvements in production efficiency, manufacturing cost, body sealing, structural rigidity and lightweight. For example, the installation time of its battery pack can be shortened by several minutes compared with the traditional bolt connection method, greatly improving the rhythm of the production line. Due to the high consistency of the connection point size, the seal is more reliable, which improves the safety and durability of the battery system. The enhanced body rigidity directly translates into better handling stability and collision safety.

[0083] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A modular lower vehicle body structure, characterized in that: include: An integrated lower body assembly, wherein the integrated lower body assembly is composed of an integrated cabin, an integrated rear floor, and left and right door sills respectively connected between the integrated cabin and the integrated rear floor to form an installation space for accommodating a battery pack; and an integrated CTC battery pack frame, the integrated CTC battery pack frame being suitable for installation in the installation space; Among them, the integrated CTC battery pack frame is provided with multiple first connection structures, and the integrated lower body assembly is provided with multiple second connection structures corresponding to the first connection structures; the integrated CTC battery pack frame is installed on the integrated lower body assembly in a quick snap-on manner through the cooperation of the first connection structure and the second connection structure.

2. The modular lower vehicle body structure according to claim 1, characterized in that: The first connection structure includes a plurality of lateral locking bosses respectively arranged on the left and right sides of the integrated CTC battery pack frame; the second connection structure includes a plurality of lateral card holes respectively arranged on the left and right door sills; the lateral locking bosses are connected to the integrated lower body assembly through the corresponding lateral card holes.

3. The modular lower vehicle body structure according to claim 2, characterized in that: It also includes a left battery fixing plate and a right battery fixing plate; the left battery fixing plate is arranged on the inner side of the left door sill, and the right battery fixing plate is arranged on the inner side of the right door sill; the left battery fixing plate and the right battery fixing plate are provided with lateral slots corresponding to the lateral locking bosses, and the lateral locking bosses engage with the lateral slots after passing through the lateral locking holes.

4. The modular lower vehicle body structure according to claim 3, characterized in that: An open groove is provided on the outer wall of the lateral locking boss; the lateral slot includes a through hole for the lateral locking boss to pass through and a limiting slot connected to the through hole; after the lateral locking boss passes through the through hole, the battery fixing plate and the door sill move relative to each other, so that the slot wall of the limiting slot is stuck in the open slot.

5. The modular lower vehicle body structure according to claim 1, characterized in that: The first connection structure also includes at least one front fixing hole arranged at the front end of the integrated CTC battery pack frame, and at least one rear fixing hole arranged at the rear end of the integrated CTC battery pack frame; the second connection structure also includes at least one front plug connector arranged on the integrated cabin and corresponding to the front fixing hole, and at least one rear plug connector arranged on the integrated rear floor and corresponding to the rear fixing hole.

6. The modular lower vehicle body structure according to claim 5, characterized in that: The front plug connector and the rear plug connector both include elastic members, and the elastic members provide a pre-tightening force after the plug connector is inserted into the fixing hole.

7. A vehicle, characterized in that: Comprising a modular lower vehicle body structure according to any one of claims 1 to 6.

8. A method for assembling a modular lower vehicle body structure, characterized in that: The following steps are involved: Preparing an integrated lower vehicle body assembly, the preparation step comprising: connecting the integrated cabin, the integrated rear floor, the left door sill, and the right door sill to enclose a mounting space for accommodating the battery pack; Providing an integrated CTC battery pack frame, wherein the integrated CTC battery pack frame is provided with a plurality of first connection structures; The integrated CTC battery pack frame is assembled to the integrated lower body assembly, and the assembly step includes: quickly snap-fitting the first connecting structure with the second connecting structure provided on the integrated lower body assembly to fix the integrated CTC battery pack frame in the installation space.

9. The assembly method according to claim 8, wherein the step of assembling the integrated CTC battery pack frame to the integrated lower vehicle body assembly specifically comprises: Lift the integrated CTC battery pack frame from bottom to top into the installation space; Align the multiple lateral locking bosses on both sides of the integrated CTC battery pack frame with the multiple lateral locking holes on the left and right door sills respectively; The lateral slots on the left battery fixing plate and the right battery fixing plate arranged on the inner sides of the left door sill and the right door sill are engaged with the lateral locking bosses to achieve locking.

10. The assembly method according to claim 9, characterized in that: An open groove is provided on the outer wall of the lateral locking boss, and the lateral locking groove includes a through hole and a limiting groove connected to the through hole; the engaging step is specifically as follows: Passing the lateral locking boss through the through hole; The battery fixing plate and the door sill slide relative to each other, so that the groove wall of the limiting groove is inserted into the opening groove.

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