A front floor assembly structure, chassis system and vehicle

Abstract

This invention relates to the field of hybrid vehicle front floor structure technology, and in particular to a front floor assembly structure, chassis system, and vehicle. The invention utilizes front floor sill beams that overlap with both the door ring body and the front floor body via flanges, forming a closed cross-section cavity. Furthermore, the front end of the front floor sill beam overlaps with the engine compartment connecting plate, and the rear end overlaps with the rear floor longitudinal beam, forming a complete longitudinal force transmission path. A frame space for installing the battery pack is formed between the two front floor sill beams. By eliminating the symmetrically arranged front floor longitudinal beams in traditional front floor assemblies, the longitudinal force transmission function is transferred to the front floor sill beams on both sides, thereby freeing up a spacious and regular frame space between the two front floor sill beams below the front floor body. This frame space can accommodate a larger battery pack assembly, effectively improving the pure electric range of hybrid vehicles and resolving the contradiction between the placement of a large-capacity battery pack and the limited front floor space.

Description

Technical Field

[0001] This invention relates to the field of front floor structure technology for hybrid vehicles, and in particular to a front floor assembly structure, chassis system, and vehicle. Background Technology

[0002] The existing front floor assembly has longitudinal beams arranged on both sides below the floor to form a longitudinal collision force transmission frame. The battery pack of hybrid vehicles is installed between the two front floor longitudinal beams. The space limitation between the front floor longitudinal beams means that the battery packs configured in existing hybrid vehicles can only meet the pure electric range requirement of about 120km, which can no longer meet the development trend of the hybrid market to improve the range.

[0003] If the battery pack is suspended entirely below the front floor longitudinal beam to increase its volume, the bottom of the battery pack will be significantly lower than the ground, resulting in insufficient minimum ground clearance for the vehicle, a marked decrease in off-road performance, and an increased risk of damage to the bottom of the battery pack from impacts. If the front floor longitudinal beam is removed entirely to free up space for the battery pack, the front floor assembly will lose its longitudinal load-bearing frame, and both collision safety performance and body rigidity will fail to meet design requirements. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a front floor assembly structure, chassis system and vehicle to solve the above problems.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: Firstly, a front floor assembly structure includes: The front floor sill beams are located on both sides of the front floor body. The front floor sill beams are connected to the door ring body and the front floor body respectively by flange overlap to form a closed cross-section cavity. The front end of the front floor sill beam overlaps with the engine compartment connecting plate and the rear end overlaps with the rear floor longitudinal beam to form a complete longitudinal force transmission path. Battery pack mounting points are provided on the front floor sill beams, and a frame space for installing the battery pack is formed between the two front floor sill beams.

[0006] As a further implementation, the front floor sill beam includes a left front floor sill beam and a right front floor sill beam. A battery pack reinforcing plate is provided on the side of the front floor sill beam near the closed cross-section cavity, and a nut for installing the battery pack is provided on the battery pack reinforcing plate.

[0007] As a further implementation, both the left front floor sill beam and the right front floor sill beam have an L-shaped cross-section structure. The L-shaped cross-section structure is welded to the door ring body and the front floor body respectively by flanges to form a closed cross-section cavity.

[0008] As a further implementation, the front floor sill beam and the engine compartment connecting plate are welded together on four sides, and the front floor sill beam and the rear floor longitudinal beam are welded together on four sides.

[0009] As a further implementation, front floor cover plates are provided on both sides of the front end of the front floor body; the front floor body is also provided with a front seat crossbeam assembly, and in the overlapping area between the front seat crossbeam assembly and the front floor body, the front floor body adopts a partial secondary flange structure.

[0010] As a further implementation, the partial secondary flange structure includes a first flange and a second flange. The first flange overlaps with the side of the door ring body, and the second flange overlaps with the upper surface of the door ring body. Together with the flange of the front seat crossbeam assembly, they form a three-layer plate welded structure.

[0011] As a further implementation, the three-layer plate welding structure is formed by welding the upper surface of the door ring body, the second flange of the front floor body, and the flange of the seat beam assembly together.

[0012] As a further implementation, the front seat crossbeam assembly includes a front seat front crossbeam and a front seat rear crossbeam; The front crossbeam and the rear crossbeam of the front seat are both overlapped on the front floor body and welded to the center channel assembly. The two ends of the front crossbeam and the rear crossbeam of the front seat are respectively overlapped and welded to the second flange through flanges.

[0013] As a further implementation, the central channel assembly is located in the middle of the front floor body and includes a central channel body, a central channel front reinforcing plate, a central channel rear reinforcing plate, and a central channel upper cover plate. The central channel front reinforcing plate and the central channel rear reinforcing plate are respectively welded to the front end and the middle of the central channel body, and the central channel upper cover plate is welded to the top of the central channel body.

[0014] As a further implementation, both the front crossbeam and the rear crossbeam of the front seat are U-shaped cross-section structural components. The rear crossbeam of the front seat is equipped with a seat mounting bracket. The front crossbeam of the front seat is positioned directly opposite the central channel body and the rear reinforcing plate of the central channel to form a complete force transmission channel structure.

[0015] As a further implementation, the front seat rear crossbeam is an integrated crossbeam structure that runs through the width of the vehicle body and is welded onto the front floor body and the center tunnel body.

[0016] As a further implementation, a rear crossbeam reinforcing plate is welded inside the rear crossbeam of the front seat, and the top surface of the rear crossbeam reinforcing plate is provided with a groove rib, forming a cavity between the top surface of the groove rib and the top surface of the rear crossbeam of the front seat.

[0017] As a further implementation, the front floor body also includes a front floor reinforcement plate, which is welded to the rear side of the front floor body to reinforce the local rigidity of the front floor body.

[0018] As a further implementation, the front floor body is welded to the engine compartment assembly, the rear floor assembly, and the door ring body to form a complete lower vehicle frame structure.

[0019] As a further implementation, the engine compartment assembly includes a subframe connecting plate, which is welded to the front end of the front floor body, and the engine compartment connecting plate is located on both sides of the subframe connecting plate.

[0020] As a further implementation, the rear floor assembly includes a rear floor connecting plate that overlaps and connects to the rear side of the front floor body, and the rear floor longitudinal beams are located on both sides of the rear floor connecting plate.

[0021] As a further implementation, a battery pack mounting point is provided at the bottom front end of the lower vehicle frame structure; the bracket on the side of the battery pack is connected to the nut on the battery pack reinforcing plate by a fastening connector.

[0022] Secondly, a chassis system comprising a front floor assembly structure as described in any of the above.

[0023] Thirdly, a vehicle includes an engine compartment assembly, a rear floor assembly, a door ring body, and a front floor assembly structure as described in any one of the above. The front ends of the front floor sill beams on both sides of the front floor body are lap-welded to the engine compartment connecting plate, the rear ends of the front floor sill beams are lap-welded to the rear floor longitudinal beam, and the front floor sill beams are lap-welded to the door ring body, forming a complete vehicle body force transmission path frame.

[0024] As a further implementation, the vehicle is a hybrid model, and a battery pack is arranged in the frame space between the front floor sill beams on both sides of the front floor body. The battery pack is connected to the vehicle body through the battery pack mounting point on the front floor sill beam.

[0025] The beneficial effects of the present invention are as follows: The present invention features a front floor sill beam that overlaps with both the door ring body and the front floor body via flanges, forming a closed cross-section cavity. Furthermore, the front end of the front floor sill beam overlaps with the engine compartment connecting plate, and the rear end overlaps with the rear floor longitudinal beam, forming a complete longitudinal force transmission path. A frame space for installing the battery pack is formed between the two front floor sill beams. By eliminating the symmetrically arranged front floor longitudinal beams in the traditional front floor assembly, the longitudinal force transmission function is transferred to the front floor sill beams on both sides, thereby releasing a spacious and regular frame space between the two front floor sill beams below the front floor body. This frame space can accommodate a larger battery pack assembly, increasing the pure electric range of hybrid vehicles from approximately 120km in the traditional solution to over 210km, effectively resolving the contradiction between the placement of a large-capacity battery pack and the limited space on the front floor.

[0026] By eliminating the traditional front floor longitudinal beams that originally protruded from the bottom of the front floor body, the battery pack assembly can be directly embedded within the frame space formed by the front floor sill beams on both sides. The bottom mounting surface of the battery pack assembly is raised by approximately 40mm. Compared to the traditional structure where the battery pack is suspended under the longitudinal beams, the vehicle's minimum ground clearance is significantly increased, greatly enhancing the vehicle's ability to pass through complex road conditions and off-road scenarios, while also reducing the safety risk of scratch damage to the bottom of the battery pack.

[0027] The front end of the front floor sill beam is welded to the engine compartment connecting plate on all four sides using a four-sided lap joint, and the rear end is welded to the rear floor longitudinal beam on all four sides using a four-sided lap joint. The outer side of the front floor sill beam is lap-welded to the door ring body to form a closed cross-section cavity, thus constructing a high-rigidity longitudinal force transmission path that integrates the engine compartment connecting plate, the front floor sill beam, and the rear floor longitudinal beam. In frontal collisions, offset collisions, and side pole impacts, the collision load can be rapidly dispersed and transferred rearward through the front floor sill beam and the battery pack assembly frame connected to it, effectively preventing the passenger compartment from being crushed and deformed, and protecting the safety of the occupants and the battery pack. CAE analysis has verified that the torsional stiffness of the vehicle body of this invention is increased by approximately 2600 N·m / deg compared to the original traditional longitudinal beam solution, fully meeting the relevant collision, pole impact, and collision safety regulations.

[0028] At the junction where the front seat crossbeam assembly overlaps with the front floor body and door ring body, the front floor body adopts a partial secondary flange structure. The first flange overlaps and is welded to the side of the door ring body to form a flat and continuous joint, which facilitates the uniform application of sealant and fully meets the requirements for electrophoresis coating and waterproof sealing. The second flange overlaps to the upper surface of the door ring body and overlaps with the upper flange of the seat crossbeam, forming a three-layer plate welded structure composed of the upper surface of the door ring body, the second flange of the front floor body, and the upper flange of the seat crossbeam. This greatly enhances the lateral connection rigidity and sealing reliability at this junction and completely solves the problem of sealing failure that is prone to occur in traditional structures in this area. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a schematic diagram of the front floor assembly structure in an embodiment of the present invention; Figure 2 This is a bottom view of the front floor assembly structure in an embodiment of the present invention; Figure 3 This is a schematic diagram of the overlapping structure of the front floor assembly, the engine compartment assembly, and the rear floor assembly in an embodiment of the present invention; Figure 4 This is a schematic diagram of the battery pack mounting point structure in an embodiment of the present invention; Figure 5 This is a schematic diagram of the overlapping structure of the front floor threshold beam, the front floor body, and the door ring body in an embodiment of the present invention. Figure 6 This is a schematic diagram of the overlapping structure of the front floor body, the front crossbeam of the front seat, and the door ring body in an embodiment of the present invention; Figure 7 This is a schematic diagram of the battery pack reinforcement plate structure in an embodiment of the present invention; Figure 8 This is a schematic diagram of the overlapping structure of the front floor sill beam and the engine compartment connecting plate in an embodiment of the present invention; Figure 9 This is a schematic diagram of the overlapping structure of the front floor threshold beam and the rear floor longitudinal beam in an embodiment of the present invention; Figure 10 This is a schematic diagram of the overlapping structure of the front seat and rear crossbeam in an embodiment of the present invention; Figure 11 This is a schematic diagram of the rear crossbeam structure of the front seat in an embodiment of the present invention; Figure 12 This is a schematic diagram of the battery pack installation structure in an embodiment of the present invention; Figure 13 This is a schematic cross-sectional view of the front crossbeam of the front seat in an embodiment of the present invention; Figure 14 This is a schematic cross-sectional view of the rear crossbeam of the front seat in an embodiment of the present invention; Figure 15 This is a cross-sectional view of the front crossbeam of the front seat in an embodiment of the present invention.

[0031] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0032] The components are: 1. Front floor cover plate, 2. Front floor body, 3. Front seat front crossbeam, 4. Front seat front crossbeam connecting plate, 5. Front seat rear crossbeam, 6. Front seat rear crossbeam connecting plate, 7. Center tunnel body, 8. Center tunnel top cover plate, 9. Front floor reinforcement plate; 10. Center tunnel front reinforcement plate, 11. Front floor sill beam, 12. Center tunnel rear reinforcement plate, 13. Rear body of front longitudinal beam, 14. Engine compartment connecting plate, 15. Door ring body, 16. Rear floor longitudinal beam, 17. Rear sill section, 18. Subframe connecting plate, 19. Rear floor connecting plate, 20. Battery pack, 21. Battery pack mounting point, 22. Battery pack reinforcement plate, 23. Rear crossbeam reinforcement plate, 24. Groove rib, 25. Bracket, 26. Fastening connector, 201. First flange, 202. Second flange, 501. Seat mounting bracket. Detailed Implementation

[0033] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] Example 1 In a typical embodiment of the present invention, reference is made to Figures 1-15 As shown, a front floor assembly structure is mainly used in the lower body frame of hybrid vehicles (including plug-in hybrid electric vehicles (PHEVs) and range-extended hybrid electric vehicles (REEVs)).

[0035] like Figures 1-2 As shown, the front floor assembly structure is assembled by welding core components such as the front floor body 2, front floor sill beams 11 located on the left and right sides of the front floor body 2, the center channel assembly, the front seat crossbeam assembly, and the front floor reinforcement plate 9. This invention completely eliminates the two symmetrical front floor longitudinal beams arranged longitudinally under the floor in the traditional front floor assembly, and reconstructs the longitudinal force transmission function to the front floor sill beams 11 on both sides. A high-rigidity closed section cavity is formed by lap welding of the front floor sill beams 11 with the door ring body 15 and the front floor body 2. At the same time, a local secondary flange structure is introduced in the key lap area at the edge of the front floor body 2, which takes into account multiple performance requirements such as collision safety, body rigidity, large space arrangement of battery pack, and paint sealing.

[0036] like Figure 1 , Figure 2 and Figure 5As shown, the front floor sill beams 11 are symmetrically arranged on the left and right sides of the bottom of the front floor body 2, with one on the left and one on the right, respectively called the left front floor sill beam and the right front floor sill beam. The two are symmetrical and mirror images of each other. The front floor sill beams 11 are made of high-strength hot-formed steel plate, with material grade CR980 / 1300HS and a thickness of 1.5mm.

[0037] The main body of the left and right front floor sill beams has an L-shaped cross-section, meaning it has a horizontal flange and a vertical web along the vehicle body cross-section, connected by a rounded transition. This L-shaped cross-section structure ensures its own bending stiffness while providing ample welding flange area for multi-faceted overlap with the door ring body 15 and the front floor body 2.

[0038] like Figure 5 As shown, the outer flange of the front floor sill beam 11 is fitted to the inner side of the door ring body 15 and connected by resistance spot welding; the upper flange of the front floor sill beam 11 is fitted to the lower side surface of the front floor body 2 and connected by spot welding. Thus, the front floor sill beam 11, the door ring body 15, and the front floor body 2 together form a closed rectangular cavity (closed cavity) in the cross-section of the vehicle body. In an optional example, the cross-sectional dimensions of this rectangular closed cavity are approximately 58mm × 89mm (width × height).

[0039] This closed-section cavity extends and runs through the longitudinal X direction of the vehicle body, possessing extremely high bending and torsional section moduli, and serves as the core load-bearing framework for the longitudinal and lateral stiffness of the entire front floor area. Since the closed cavity formed by the front floor sill beam 11 and the door ring body 15 already possesses sufficient stiffness, it can completely replace the front floor longitudinal beam.

[0040] like Figure 3 and Figure 8 As shown, at the front end of the front floor sill beam 11, the front floor sill beam 11 and the engine compartment connecting plate 14 of the engine compartment assembly are welded together in a four-sided lap joint manner. Specifically, the cross section of the engine compartment connecting plate 14 is welded to the four sides (including the horizontal flange surface, the vertical web surface, and the two sets of flange surfaces) at the front end of the front floor sill beam 11, forming an overlapping area. Continuous resistance spot welding or plug welding is applied to each side, so that the engine compartment connecting plate 14 and the front floor sill beam 11 form a high-strength multi-sided welded joint at the front end node.

[0041] The launch hatch connecting plate 14 is made of HC340 / 590DPD+Z cold-rolled duplex steel with a thickness of 1.5mm. Its front end is lap-welded to the rear body 13 of the front longitudinal beam, and its rear end is lap-welded to the front floor sill beam 11 on all four sides. At the same time, the bottom of the launch hatch connecting plate 14 can also be lap-welded to the bottom of the front end of the door ring body 15, so as to smoothly introduce the longitudinal beam load of the launch hatch area into the cavity section of the front floor sill beam 11.

[0042] like Figure 3 and Figure 9 As shown, at the rear end of the front floor sill beam 11, the front floor sill beam 11 and the rear floor longitudinal beam 16 of the rear floor assembly are also welded in a four-sided lap joint manner. The rear floor longitudinal beam 16 is made of CR980 / 1300HS hot-formed steel with a thickness of 1.5mm. The four-sided lap joint manner is the same as that of the engine compartment connecting plate 14, forming an overlapping lap joint area, and continuous resistance spot welding or plug welding is applied to each area. The rear end of the front floor sill beam 11 extends to the rear sill section 17, and the rear sill section 17 is lap-welded to the rear end of the front floor sill beam 11 and the rear end of the door ring body 15 to ensure the continuity of the sill area cross section.

[0043] Through the four-sided lap welding at both ends, a high-rigidity longitudinal continuous force transmission path is constructed, consisting of the rear body 13 of the front longitudinal beam, the engine compartment connecting plate 14, the front floor sill beam 11, and the rear floor longitudinal beam 16.

[0044] When a frontal collision occurs, the impact force is first received and partially absorbed by the front longitudinal beam of the engine compartment (the rear body 13 of the front longitudinal beam). Subsequently, the residual impact load is smoothly transferred to the front floor sill beam 11 through the four lap welds of the engine compartment connecting plate 14. The front floor sill beam 11, with its high-strength thermoformed material and the high bending stiffness provided by the closed cross-section cavity, further efficiently transfers the load to the rear floor longitudinal beam 16, and then disperses it to the rear of the vehicle through the rear floor assembly frame.

[0045] The entire force transmission path is continuous and uninterrupted, effectively preventing the accumulation of collision force in the front floor area, which could lead to compression and deformation of the passenger compartment. Furthermore, the closed cavity formed by the front floor sill beam 11 and the door ring body 15 can directly withstand the lateral impact force from the side walls during a side collision, forming a complete lateral force transmission network in conjunction with the front seat crossbeam assembly. CAE analysis has verified that the torsional stiffness of the vehicle body in this embodiment is increased by approximately 2600 N·m / deg compared to the traditional front floor longitudinal beam solution, fully meeting the requirements of collision, pole impact, and collision safety regulations.

[0046] like Figure 4 , Figure 7 and Figure 12As shown, since the traditional front floor longitudinal beam under the front floor body 2 has been completely eliminated, a spacious and flat rectangular frame space is formed between the front floor sill beams 11 on both sides under the front floor body 2, which is specifically used to arrange the battery pack 20. Compared with the existing technology, a relatively larger capacity battery pack 20 can be arranged to achieve the purpose of improving the driving range.

[0047] like Figure 7 As shown, a battery pack reinforcing plate 22 is welded along the longitudinal direction of the front floor sill beam 11 in the bending angle region near the inner side of the closed section cavity and in the horizontal flange region. A through hole is provided in the corresponding horizontal flange region.

[0048] The battery pack reinforcing plate 22 is an L-shaped stamped thickened steel plate, which is welded to the inner surface of the front floor sill beam 11 to form a robust reinforcing structure. The battery pack reinforcing plate 22 is segmented along the longitudinal direction of the front floor sill beam 11 and is installed at the corresponding position of each battery pack mounting point 21. Mounting holes are pre-drilled on the battery pack reinforcing plate 22, and M10 nuts are fixedly welded to the back of the mounting holes using a projection welding process to facilitate cooperation with the fastening connector 26 to fix the bracket 25 of the battery pack 20.

[0049] The front floor sill beam 11 has a through hole at the position corresponding to the battery pack reinforcement plate 22, so that the fastening connector 26 at the battery pack mounting point 21 can enter from the outside and engage with the M10 nut.

[0050] like Figure 4 and Figure 12 As shown, multiple brackets 25 extend outward from the outer walls of the left and right sides of the battery pack 20. Preferably, four brackets 25 are arranged on each side, resulting in a total of eight mounting points. The brackets 25 are stamped from high-strength steel plates, and their ends are provided with through holes corresponding to M10 nuts. During vehicle assembly, the battery pack 20 is lifted from below into the frame space between the front floor sill beams 11 on both sides, so that the through holes of each bracket 25 mate with the corresponding fastening connectors 26. The fastening connectors 26 are M10 high-strength bolts, which pass through the through holes of the brackets 25 and are screwed into the M10 nuts on the battery pack reinforcing plate 22, firmly fixing the battery pack 20 to the front floor sill beams 11, forming reliable battery pack mounting points 21.

[0051] In the prior art, the front floor longitudinal beam is located inside the front floor sill beam 11, which limits the installation space of the battery pack 20. This embodiment eliminates the front floor longitudinal beam, increasing the frame space between the left and right front floor sill beams 11, allowing for the installation of a larger battery pack 20 and thus improving the driving range. Furthermore, by designing the front floor sill beam 11 and the structure connected to it, the stress path of the newly formed longitudinal beam meets the corresponding requirements.

[0052] Because the battery pack 20 is nested within the frame space between the front floor sill beams 11 on both sides, the lateral dimension of the battery pack 20 can make full use of the entire clear width between the two sill beams, and the longitudinal dimension can make full use of the entire clear length between the engine compartment connecting plate 14 and the rear floor connecting plate 19. Compared with the traditional battery pack arrangement scheme that is limited by the front floor longitudinal beams, the usable volume of the battery pack 20 is greatly increased, and the pure electric range of the hybrid vehicle is increased from about 120km in the traditional scheme to more than 210km.

[0053] More importantly, the battery pack 20 is embedded in the frame space, and the height of its bottom mounting surface is determined by the bottom surface of the front floor sill beam 11. Compared with the traditional solution of hanging the battery pack under the bottom of the front floor longitudinal beam, the bottom of the battery pack 20 is raised by about 40mm, significantly increasing the minimum ground clearance of the vehicle. This effectively enhances the ability of hybrid SUVs or off-road vehicles to pass through complex road conditions, while greatly reducing the safety risk of the bottom of the battery pack being scraped or bumped.

[0054] like Figure 1 and Figure 2 As shown, the front floor body 2 is composed of two symmetrically stamped steel plates, the left front floor body and the right front floor body, which are welded together at the central channel body 7. Front floor cover plates 1 are welded to the left and right sides of the front end of the front floor body 2. These cover plates 1 cover the opening area at the front end of the front floor body 2, reinforcing the local rigidity of this area. They also form a closed box-shaped section together with the front floor body 2, improving the bending resistance of the front end area of ​​the front floor.

[0055] A front floor reinforcement plate 9 is welded to the rear surface of the front floor body 2. The front floor reinforcement plate 9 is a stamped reinforcing rib plate, which is arranged longitudinally along the rear of the front floor body 2. It is used to strengthen the local anti-dent stiffness and anti-vibration stiffness of the rear of the front floor body 2, suppress low-frequency plate surface vibration, and improve the NVH performance of the whole vehicle.

[0056] like Figure 5 , Figure 6 and Figure 10 As shown, the front floor body 2 adopts a partial secondary flanging structure. The front floor body 2 is also equipped with a front seat crossbeam assembly, which includes a front seat front crossbeam 3 and a front seat rear crossbeam 5. In the edge area where the front seat crossbeam assembly (including the front seat front crossbeam 3 and the front seat rear crossbeam 5) overlaps with the front floor body 2, the front floor body 2 adopts a partial secondary flanging structure.

[0057] In this embodiment, the partial secondary flange structure refers to a specific local area on the edge of the front floor body 2 (i.e., the corresponding positions at the ends of the front seat front crossbeam 3 and the front seat rear crossbeam 5). Instead of using the traditional single-bend flange, the edge of the front floor body 2 is formed by two bends to create a stepped secondary flange. The partial secondary flange structure includes a first flange 201 and a second flange 202. In the remaining non-crossbeam overlapping areas on the edge of the front floor body 2, a single flange (first flange 201) is used to overlap with the side of the door ring body 15.

[0058] like Figure 6 As shown, the first flange 201 is formed by bending the edge of the front floor body 2 upwards. The plane of the first flange 201 extends vertically (or is slightly inclined), and its outer surface is closely fitted with the inner vertical surface (side surface) of the door ring body 15 and connected by resistance spot welding. The lap weld formed between the first flange 201 and the side surface of the door ring body 15 has a smooth and flat geometry, and the weld opening faces the inside of the vehicle body. The automatic glue-applying robot on the painting line can apply a continuous and uniform waterproof sealant strip to the weld without obstruction.

[0059] The sealant fully fills the gap between the first flange 201 and the side of the door ring body 15, forming a continuous and reliable waterproof sealing barrier, which meets the requirements of electrophoresis coating and waterproof sealing of the car body. It fundamentally solves the problem of uneven sealant application and water leakage caused by poor flange overlap shape in the traditional structure of this area.

[0060] like Figure 6 and Figure 10 As shown, the second flange 202 is formed by horizontally bending outward (towards the outer side of the vehicle body) from the top of the first flange 201. The plane of the second flange 202 extends horizontally and overlaps into the upper surface of the door ring body 15. There are connecting plates at both ends of the front seat front crossbeam 3 (or front seat rear crossbeam 5), wherein the end of the front seat front crossbeam 3 is the front seat front crossbeam connecting plate 4, and the end of the front seat rear crossbeam 5 is the front seat rear crossbeam connecting plate 6. Corresponding flanges are provided on the connecting plates. The flanges overlap the second flange 202 of the front floor body 2 from above, and the second flange 202 overlaps the upper surface of the door ring body 15.

[0061] Therefore, three layers of plates are stacked sequentially from bottom to top in this local area: the bottom layer is the upper surface of the door ring body 15, the middle layer is the second flange 202 of the front floor body 2, and the top layer is the upper flange at the end of the front seat front crossbeam 3 (or the front seat rear crossbeam 5). After these three layers of plates are overlapped in the same area, they are resistance-spot welded by welding clamps to form a high-strength three-layer plate welded structure.

[0062] The three-layer welded structure directly couples the lateral collision load from the seat crossbeam to the door ring body 15 through the second flange 202, greatly enhancing the lateral connection stiffness at this node and effectively improving the vehicle's ability to resist side pole impacts, preventing the door ring from squeezing and intruding into the passenger compartment during side collisions.

[0063] like Figure 13 and Figure 15 As shown, the front seat crossbeam 3 is a universal component for both sides, with two pieces installed per vehicle, symmetrically arranged on the front floor body 2. The front seat crossbeam 3 is made of high-strength hot-formed steel sheet, material grade CR980 / 1300HS, with a thickness of 1.2mm. Its main cross-section is U-shaped (Z-shaped), with the opening facing downwards. The front seat crossbeam 3 is arranged across the vehicle body in the transverse Y direction, with its middle section overlapping and welded to the side of the central tunnel body 7.

[0064] It is understood that the lap welding between the middle of the front seat crossbeam 3 and the side of the central tunnel body 7 referred to in this embodiment is actually the lap welding between the inner end of a single front seat crossbeam 3 and the side of the central tunnel body 7. Therefore, the inner ends of both the left and right front seat crossbeams 3 are lap welded to the side of the central tunnel body 7.

[0065] The two ends of the front crossbeam 3 of the front seat are welded to the second flange 202 by means of flanges. Here, the two ends of the front crossbeam 3 of the front seat refer to the outer ends of the two front crossbeams 3 of the left and right seats (away from each other).

[0066] The center channel assembly is located in the middle of the front floor body and includes a center channel body 7, a front center channel reinforcing plate 10, a rear center channel reinforcing plate 12, and a center channel top cover plate 8. The front center channel reinforcing plate 10 is located at the front end of the center channel body 7, and the rear center channel reinforcing plate 12 is located in the middle to improve the structural strength of the center channel assembly. The center channel top cover plate 8 is located on the top of the center channel body 7.

[0067] In the lateral position, the front seat front crossbeam 3 is positioned directly opposite the rear reinforcement plate 12 of the central channel body 7, aligning the lateral axis of the front seat front crossbeam 3 with the position of the reinforcement plate inside the central channel. This ensures that in the event of a side collision, the lateral impact force is transmitted from the door ring body 15 through the three-layer plate welding joint to the front seat front crossbeam 3, then laterally across the front seat front crossbeam 3 to the central channel body 7, where it is received by the rear reinforcement plate 12, and finally transmitted to the opposite door ring body 15, forming a complete and continuous lateral force transmission channel. This effectively prevents the seat crossbeam and central channel from bending and deforming and intruding into the battery pack area during a side pole collision, thus ensuring battery safety.

[0068] like Figure 11 and Figure 14As shown, the front seat rear crossbeam 5 is an integrated crossbeam structure that runs horizontally through the width of the vehicle body, with only one piece installed per vehicle. The front seat rear crossbeam 5 is made of high-strength hot-formed steel sheet, with material grade CR980 / 1300HS and a thickness of 2.0mm. Its main cross section is U-shaped. Both the front seat front crossbeam 3 and the front seat rear crossbeam 5 are U-shaped cross-section structural components with the cross-section opening facing downwards. The cross-sectional dimensions of the front seat rear crossbeam 5 are approximately 83mm × 54mm (width × height).

[0069] The rear crossbeam 5 of the front seat runs through the vehicle body in the Y direction and is welded to the front floor body 2 and the middle channel body 7.

[0070] The lower surface of the middle part of the front seat rear crossbeam 5 overlaps with the rear end of the central tunnel body 7 and is connected by resistance spot welding; the left and right sides of the front seat rear crossbeam 5 overlap with the upper surfaces of the left and right front floor bodies 2 respectively and are connected by spot welding. The left and right ends of the front seat rear crossbeam 5 are overlapped and welded to the door ring body 15 and the second flange 202 of the front floor body 2 respectively through the front seat rear crossbeam connecting plate 6, forming a three-layer plate welding node.

[0071] The integrated through-structure of this embodiment allows the rear crossbeam 5 of the front seat to be transferred directly from one door ring to the other without any intermediate joints during a lateral collision, greatly improving the efficiency of lateral force transmission and the ability to resist side impacts.

[0072] like Figure 11 and Figure 14 As shown, a rear crossbeam reinforcing plate 23 is welded to the inside of the front seat rear crossbeam 5. The rear crossbeam reinforcing plate 23 is a stamped U-shaped part, with its two flanges welded to the inner sidewall of the front seat rear crossbeam 5. The top surface of the rear crossbeam reinforcing plate 23 is stamped with a transversely extending groove rib 24. A gap of about 6mm is maintained between the top surface of the groove rib 24 and the inner wall of the top surface of the front seat rear crossbeam 5, thereby forming a transverse cavity section inside the front seat rear crossbeam 5. This greatly increases the moment of inertia of the front seat rear crossbeam 5 section, enhances its bending stiffness and torsional stiffness, and enables the front seat rear crossbeam 5 to maintain its section integrity under side pole impact conditions, making it less prone to bending and collapse.

[0073] The rear crossbeam reinforcement plate 23 is made of CR980 / 1300HS hot-formed steel with a thickness of 2.0mm, which is a differentiated development and design.

[0074] A seat mounting bracket 501 is welded to the upper surface of the rear crossbeam 5 of the front seat for mounting the front seat. The seat mounting bracket 501 includes one universal mounting bracket on each side and one mounting beam in the middle, providing a total of 4 seat mounting points to meet the installation needs of the driver and passenger seats.

[0075] like Figure 1 , Figure 2 and Figure 13 As shown, the central tunnel assembly is located at the transverse center of the front floor body 2 along the longitudinal X direction of the vehicle body. It is composed of the central tunnel body 7, the central tunnel front reinforcing plate 10, the central tunnel rear reinforcing plate 12, and the central tunnel upper cover plate 8, which are welded together.

[0076] The central tunnel body 7 is a stamped channel-shaped steel plate with an inverted U-shaped cross-section, opening downwards and extending longitudinally. The left and right flanges of the central tunnel body 7 overlap with the upper surfaces of the left and right front floor bodies 2, respectively, and are connected by resistance spot welding, forming the basic connection between the central tunnel body 7 and the front floor bodies 2. The central tunnel front reinforcing plate 10 is a stamped reinforcing plate welded to the front end of the inner cavity of the central tunnel body 7. Its shape matches the cross-section of the inner cavity of the central tunnel body 7, and it is welded to the inner sidewall of the central tunnel body 7 on multiple surfaces. This enhances the crush resistance of the front end area of ​​the central tunnel, preventing the front end of the central tunnel from collapsing first in a frontal collision.

[0077] The rear reinforcing plate 12 of the center tunnel is a stamped reinforcing plate, welded to the rear center of the inner cavity of the center tunnel body 7. It is welded to the inner wall of the center tunnel body 7 on multiple sides to enhance the rigidity of the rear part of the center tunnel and to form a corresponding support for the lateral force transmission node with the front crossbeam 3 of the front seat. The upper cover plate 8 of the center tunnel is welded to the top of the center tunnel body 7, significantly improving the overall bending and torsional section modulus of the center tunnel assembly.

[0078] The central channel assembly and the front seat crossbeam 3 are aligned longitudinally. Specifically, the front seat crossbeam 3 is positioned laterally directly opposite the rear reinforcement plate 12 of the central channel body 7, aligning them longitudinally (X-direction). This ensures that in a side collision, the lateral force transmitted from the front seat crossbeam 3 to the central channel is directly absorbed by the rear reinforcement plate 12, preventing local bending deformation of the central channel due to misalignment. This design effectively prevents the seat crossbeam and central channel from bending and deforming and intruding into the battery pack area during a side pole impact, which is crucial for ensuring battery safety.

[0079] like Figure 3 As shown, after the welding and assembly of the internal components are completed, the front floor assembly structure is welded together with the engine compartment assembly, the rear floor assembly, and the door ring bodies 15 on the left and right sides to form a complete lower body frame structure.

[0080] At the connection between the front floor assembly and the engine compartment assembly, the subframe connecting plate 18 in the engine compartment assembly is located at the lateral center of the bottom of the engine compartment. Its rear end is welded to the front end of the front floor body 2. It is used to install the front chassis subframe and the front suspension system and bear the vertical, longitudinal and lateral loads from the front suspension.

[0081] The engine compartment connecting plate 14 is located on the left and right sides of the subframe connecting plate 18, extending longitudinally. The front end of the engine compartment connecting plate 14 is lap-welded to the rear end of the rear body 13 of the front longitudinal beam in the engine compartment area, and the rear end is lap-welded to the front end of the front floor sill beam 11 on all four sides. The rear body 13 of the front longitudinal beam is the rear section structure of the engine compartment longitudinal beam. Its front end is connected to the front longitudinal beam of the engine compartment, and its rear end introduces the collision load of the engine compartment longitudinal beam into the longitudinal force transmission path of the front floor sill beam 11 through the engine compartment connecting plate 14.

[0082] At the connection between the front floor assembly and the rear floor assembly, the rear floor connecting plate 19 is lap-welded to the rear side of the front floor body 2. The rear floor connecting plate 19 is arranged laterally, connecting and transitioning the front floor body 2 with the rear floor panel of the rear floor assembly. The rear floor longitudinal beam 16 is located on the left and right sides of the rear floor connecting plate 19. The front end of the rear floor longitudinal beam 16 is lap-welded to the rear end of the front floor sill beam 11 on all four sides. The rear floor longitudinal beam 16 extends longitudinally backward, bearing the collision load from the front floor sill beam 11 and further transferring and dispersing it to the rear floor assembly frame. On the outside of the lap joint between the rear end of the front floor sill beam 11 and the rear floor longitudinal beam 16, the rear section 17 of the sill is lap-welded to the rear end of the front floor sill beam 11 and the door ring body 15, ensuring the continuity of the closed cross-section cavity in the sill area at the junction of the front and rear floors and avoiding stress concentration caused by abrupt changes in cross-section.

[0083] At the connection between the front floor assembly and the side door ring body 15, the door ring body 15 is symmetrically arranged on the left and right sides. Its inner side surface is lapped and welded to the outer flange of the front floor sill beam 11 to form a closed cross-section cavity. The upper surface of the door ring body 15 forms a three-layer plate welded structure with the second flange 202 of the front floor body 2 and the upper flange at the end of the seat crossbeam. The side of the door ring body 15 is lapped and welded to the first flange 201 of the front floor body 2 to meet the coating sealing requirements. Through the above multi-faceted welding connection, the door ring body 15 and the front floor assembly structure form a highly integrated overall load-bearing frame in the horizontal and vertical directions.

[0084] In a frontal collision, the collision force is transmitted from the front of the vehicle. After the energy is absorbed by the rear body 13 of the front longitudinal beam, the residual force is transmitted to the front floor sill beams 11 on both sides through the four-sided lap weld of the engine compartment connecting plate 14. The front floor sill beam 11, with the high rigidity provided by the CR980 / 1300HS hot-formed high-strength steel and the closed cross-section cavity, efficiently transmits the collision force longitudinally to the rear floor longitudinal beam 16. Then, it is distributed to the rear of the vehicle through the rear floor assembly frame, forming a complete longitudinal force transmission chain from front to back, consisting of the rear body 13 of the front longitudinal beam, the engine compartment connecting plate 14, the front floor sill beam 11, and the rear floor longitudinal beam 16.

[0085] The battery pack 20, which is arranged between the front floor sill beams 11 on both sides, has a high-strength outer shell that is rigidly connected to the battery pack reinforcement plate 22 on the front floor sill beam 11 through the bracket 25 and the fastening connector 26. During a collision, it participates in the force-bearing with the front floor sill beam 11, further enhancing the deformation resistance of the overall frame and effectively protecting the safety of the passenger compartment and the battery pack.

[0086] In the case of a side pillar impact, the impact force first acts on the side door ring body 15. The door ring body 15 bears the lateral crushing force through the closed cross-section cavity formed by it and the front floor sill beam 11. At the same time, the impact force is transmitted to the front seat front crossbeam 3 (or the front seat rear crossbeam 5) through the three-layer plate welding node at the second flange 202 of the front floor body 2, and then laterally transmitted to the center channel body 7 and the center channel rear reinforcing plate 12 through the crossbeam, and finally transmitted to the opposite side door ring body 15, forming a complete lateral force transmission channel.

[0087] Specifically, the impact force transmitted to the front seat front crossbeam 3 via the three-layer plate welding joint at the second flange 202 of the front floor body 2 is mainly transmitted to the opposite door ring body 15 through the central tunnel body 7 and the central tunnel rear reinforcement plate 12, forming a complete lateral force transmission channel. The impact force transmitted to the front seat rear crossbeam 5 via the three-layer plate welding joint at the second flange 202 of the front floor body 2 is transmitted to the opposite door ring body 15 through the integrated crossbeam structure (front seat rear crossbeam 5) arranged horizontally. This part of the impact force is transmitted by the front seat rear crossbeam 5 and the rear end of the central tunnel body 7, without passing through the central tunnel rear reinforcement plate 12.

[0088] Because the front seat front crossbeam 3 is positioned directly opposite the central channel rear reinforcement plate 12, the lateral force transmission has no bending path, resulting in extremely high force transmission efficiency and effectively preventing the door ring from intruding and deforming into the passenger compartment and battery pack area during a side collision. The integrated through-structure of the front seat rear crossbeam 5 and the closed cavity section formed by the rear crossbeam reinforcement plate 23 and the groove rib 24 further enhance the lateral force transmission stiffness, ensuring that the front seat rear crossbeam 5 is not prone to bending or collapsing under side pole impact conditions, allowing the collision force to be transmitted laterally without obstruction.

[0089] The approximately 58mm × 89mm closed section cavity formed by the front floor sill beam 11 and the door ring body 15 has a torsional section modulus that is much higher than that of the traditional open section front floor longitudinal beam structure.

[0090] The multiple lateral closed frames formed by the front seat crossbeam 3, the rear seat crossbeam 5, and the central tunnel assembly, along with the high-rigidity node connections provided by the partially double-flanged three-layer welded structure of the front floor body 2, together construct a highly statically indeterminate lower body frame system. CAE analysis verifies that the torsional stiffness of this embodiment is increased by approximately 2600 N·m / deg compared to the traditional front floor longitudinal beam scheme, resulting in significant improvements in both vehicle dynamic response and durability.

[0091] The lap weld between the first flange 201 of the front floor body 2 and the side of the door ring body 15 is flat, with good adhesive accessibility and continuous and uniform sealant application, fully meeting the requirements of electrophoresis coating and waterproof sealing of the vehicle body. It effectively prevents rainwater and mud from seeping into the passenger compartment from the gaps at the bottom of the door, ensuring the waterproof sealing performance of the passenger compartment and the corrosion resistance and durability of the vehicle body panels.

[0092] Furthermore, since the closed cavity formed by the front floor sill beam 11 and the door ring body 15 has sufficient rigidity, it can completely replace the traditional front floor longitudinal beam. At the same time, it reduces the number of stamping dies and welding processes, achieving lightweighting, which helps to reduce manufacturing costs and improve production efficiency.

[0093] The front floor sill beams overlap with the door ring body and the front floor body through flanges, forming a closed cross-section cavity. The front end of the front floor sill beam overlaps with the engine compartment connecting plate, and the rear end overlaps with the rear floor longitudinal beam, forming a complete longitudinal force transmission path. A frame space for installing the battery pack is formed between the two front floor sill beams. By eliminating the symmetrically arranged front floor longitudinal beams in the traditional front floor assembly, the longitudinal force transmission function is transferred to the front floor sill beams on both sides, thereby freeing up a spacious and regular frame space between the two front floor sill beams under the front floor body. This frame space can accommodate a larger battery pack assembly, increasing the pure electric range of the hybrid vehicle from about 120km in the traditional solution to more than 210km, effectively solving the contradiction between the placement of a large-capacity battery pack and the limited space on the front floor.

[0094] By eliminating the traditional front floor longitudinal beams that originally protruded from the bottom of the front floor body, the battery pack assembly can be directly embedded within the frame space formed by the front floor sill beams on both sides. The bottom mounting surface of the battery pack assembly is raised by approximately 40mm. Compared to the traditional structure where the battery pack is suspended under the longitudinal beams, the vehicle's minimum ground clearance is significantly increased, greatly enhancing the vehicle's ability to pass through complex road conditions and off-road scenarios, while also reducing the safety risk of scratch damage to the bottom of the battery pack.

[0095] The front end of the front floor sill beam is welded to the engine compartment connecting plate in a four-sided lap joint manner, and the rear end is welded to the rear floor longitudinal beam in a four-sided lap joint manner. The outer side of the front floor sill beam is welded to the door ring body to form a closed cross-section cavity, thereby constructing a high-rigidity longitudinal force transmission path that integrates the engine compartment connecting plate, the front floor sill beam, and the rear floor longitudinal beam.

[0096] In frontal, offset, and side pole impact scenarios, the collision load can be rapidly dispersed rearward through the front floor sill beam and the battery pack assembly frame connected to it, effectively preventing compression deformation of the passenger compartment and protecting the safety of the occupants and battery pack. CAE analysis has verified that the torsional stiffness of the vehicle body of this invention is increased by approximately 2600 N·m / deg compared to the original traditional longitudinal beam solution, fully meeting the relevant collision, pole impact, and collision safety regulations.

[0097] At the junction where the front seat crossbeam assembly overlaps with the front floor body and door ring body, the front floor body adopts a partial secondary flange structure. The first flange overlaps and is welded to the side of the door ring body to form a flat and continuous joint, which facilitates the uniform application of sealant and fully meets the requirements for electrophoresis coating and waterproof sealing. The second flange overlaps to the upper surface of the door ring body and overlaps with the upper flange of the seat crossbeam, forming a three-layer plate welded structure composed of the upper surface of the door ring body, the second flange of the front floor body, and the upper flange of the seat crossbeam. This greatly enhances the lateral connection rigidity and sealing reliability at this junction and completely solves the problem of sealing failure that is prone to occur in traditional structures in this area.

[0098] Example 2 In a typical embodiment of the present invention, reference is made to Figures 1-15 As shown, a chassis system includes the front floor assembly structure of Embodiment 1, and further integrates the front chassis suspension interface, the rear chassis interface and the power battery system on this basis, forming an overall chassis solution with high structural integration, excellent rigidity, ample battery placement space and significantly improved ground clearance.

[0099] The chassis system of this embodiment comprises a front floor assembly structure (including front floor body 2, front floor sill beam 11, front seat front crossbeam 3, front seat rear crossbeam 5, center tunnel body 7, front floor reinforcement plate 9, battery pack reinforcement plate 22, etc.), a front chassis suspension interface (subframe connecting plate 18), a rear chassis interface (rear floor longitudinal beam 16, rear floor connecting plate 19), and a power battery system (battery pack 20).

[0100] Compared with existing chassis solutions, the chassis system in this embodiment has a high degree of structural integration. The closed-section cavity formed by the front floor sill beam 11 and the door ring body 15 takes into account both longitudinal load-bearing and lateral protection functions. The overall stiffness is excellent. CAE analysis verifies that the torsional stiffness is increased by about 2600 N·m / deg compared with the traditional solution. The battery placement space is greatly expanded, which can achieve a pure electric range of more than 210km. The ground clearance of the battery pack 20 is raised by about 40mm, which significantly enhances the off-road performance of the vehicle.

[0101] like Figure 3As shown, the front end of the chassis system is lap-welded to the front end of the front floor body 2 via a subframe connecting plate 18. The subframe connecting plate 18 is located at the transverse center of the engine compartment bottom, arranged along the transverse Y direction of the vehicle body. Its rear end flange overlaps with the lower surface of the front end of the front floor body 2 and is fixedly connected by resistance spot welding. The main function of the subframe connecting plate 18 is to provide an installation interface for the front chassis subframe, bear the vertical, longitudinal, and lateral dynamic loads from the front suspension system, and evenly distribute these loads to the lower body frame formed by the front floor body 2 and the front floor sill beam 11. The subframe connecting plate 18 is made of high-strength stamped steel plate, and its upper surface has multiple subframe mounting nuts for fixing the front chassis subframe to the vehicle body with bolts.

[0102] The engine compartment connecting plate 14 is symmetrically arranged on the left and right sides of the subframe connecting plate 18, extending along the longitudinal X direction of the vehicle body.

[0103] The front end of the launch hatch connecting plate 14 is lap-welded to the rear end of the front longitudinal beam body 13 in the launch hatch area, and the rear end is welded to the front end of the front floor sill beam 11 in a four-sided lap-welded manner. At the same time, the bottom of the launch hatch connecting plate 14 is also lap-welded to the bottom of the door ring body 15, further enhancing the overall connection rigidity at this node.

[0104] The rear body 13 of the front longitudinal beam is the rear section of the launch bay longitudinal beam. Its front end is connected to the front longitudinal beam of the launch bay, and its rear end is connected to the cavity section of the front floor sill beam 11 through the launch bay connecting plate 14.

[0105] When a vehicle is involved in a frontal collision, the impact force is first received and partially absorbed by the rear body 13 of the front longitudinal beam. The residual impact load is then efficiently transferred to the front floor sill beam 11 through the four lap welds of the engine compartment connecting plate 14, thus completing the introduction and dispersion of the load at the front end of the chassis.

[0106] The rear end of the chassis system is lap-welded to the rear side of the front floor body 2 via the rear floor connecting plate 19. The rear floor connecting plate 19 is arranged along the transverse Y direction of the vehicle body. Its front end flange fits and overlaps with the lower rear surface of the front floor body 2 and is fixed by spot welding. Its rear end is lap-welded to the rear floor panel of the rear floor assembly, which serves as a transition connection between the front floor assembly and the rear floor assembly. At the same time, it bears the vertical load from the rear passengers and the rear chassis system and transfers it to the overall lower body frame.

[0107] The rear floor longitudinal beam 16 is symmetrically arranged on the left and right sides of the rear floor connecting plate 19, extending along the longitudinal X direction of the vehicle body. The front end of the rear floor longitudinal beam 16 is welded to the rear end of the front floor sill beam 11 in a four-sided lap joint manner. The rear floor longitudinal beam 16 extends longitudinally rearward, receiving the collision load transmitted from the front floor sill beam 11 and further distributing it to the rear floor assembly frame. It also provides an installation interface for the rear chassis suspension system, bearing the vertical and longitudinal dynamic loads transmitted from the rear suspension.

[0108] On the outer side of the overlap joint between the rear end of the front floor sill beam 11 and the rear floor longitudinal beam 16, the rear sill section 17 is welded to the rear end of the front floor sill beam 11 and the door ring body 15. The cross-sectional shape of the rear sill section 17 is similar to that of the front floor sill beam 11. The two achieve a smooth transition of the cross-section through multi-face lap welding at the rear end joint, ensuring the continuity of the closed cross-section cavity in the sill area at the junction of the front and rear floors. This effectively avoids stress concentration and local instability caused by abrupt changes in cross-section, ensuring that the collision load can be smoothly transferred in the junction area of ​​the front and rear floors without path breakage.

[0109] like Figure 4 and Figure 12 As shown, the battery pack 20 is arranged within the frame space between the two front floor sill beams 11. This frame space is enclosed by the two front floor sill beams 11, the front engine compartment connecting plate 14 area, and the rear floor connecting plate 19 area. Since this embodiment completely eliminates the traditional front floor longitudinal beams, the frame space is maximized in both the lateral and longitudinal directions. The lateral dimension of the battery pack 20 can fully utilize the entire clear width between the two sill beams, and the longitudinal dimension can fully utilize the entire clear length between the engine compartment connecting plate 14 and the rear floor connecting plate 19. Compared with the traditional battery pack arrangement scheme limited by the front floor longitudinal beams, the usable volume of the battery pack 20 is greatly increased, and the pure electric range of the hybrid vehicle is increased from about 120km in the traditional scheme to more than 210km.

[0110] In the bending angle area near the inner side of the closed section cavity of the front floor sill beam 11, battery pack reinforcing plates 22 are welded in segments along the longitudinal direction. Mounting holes are pre-drilled on the battery pack reinforcing plates 22, and M10 nuts are fixedly welded to the back of the mounting holes using projection welding. Multiple brackets 25 extend outward from the outer walls of the left and right sides of the battery pack 20, with 4 brackets 25 arranged on each side, for a total of 8 mounting points. During vehicle assembly, the battery pack 20 is lifted from below into the frame space between the front floor sill beams 11 on both sides, aligning the mounting holes (through holes) of each bracket 25 with the corresponding M10 nuts. Then, high-strength bolts (fastening connectors 26) are passed through the through holes of the brackets 25 and screwed into the M10 nuts to firmly fix the battery pack 20 to the front floor sill beam 11, forming reliable battery pack mounting points 21.

[0111] The rigid connection between the battery pack 20 and the chassis frame not only ensures reliable fixation of the battery pack 20 but also makes a significant positive contribution to the overall rigidity of the chassis system. After the high-strength outer shell of the battery pack 20 is rigidly connected to the front floor sill beam 11 via the bracket 25 and fastening connector 26, the outer shell structure of the battery pack 20 participates in the overall stress distribution of the vehicle chassis, forming a more complete lower body load-bearing frame together with the front floor sill beam 11. This further enhances the overall deformation resistance of the chassis frame under frontal and side impact conditions. Analysis shows that the integrated connection between the battery pack 20 and the front floor sill beam 11 makes a significant contribution to improving the torsional stiffness of the chassis system, and is one of the important structural factors contributing to an increase of approximately 2600 N·m / deg in overall torsional stiffness compared to traditional solutions.

[0112] The battery pack 20 is embedded within the frame space. Regarding ground clearance, the height of its bottom mounting surface is determined by the bottom surface of the front floor sill beam 11. Since the front floor sill beam 11 is located on the side of the vehicle, its bottom surface height is basically the same as the bottom height of the side sill. Compared to the traditional solution of hanging the battery pack under the front floor longitudinal beam, the overall ground clearance of the battery pack 20 is raised by approximately 40mm. This structural elevation significantly increases the vehicle's minimum ground clearance, effectively enhancing the passability of hybrid SUVs or off-road vehicles in complex road conditions, while also greatly reducing the safety risk of the battery pack's bottom being scraped or bumped.

[0113] like Figure 3 As shown, the chassis system in this embodiment constructs a complete and efficient longitudinal and lateral bidirectional force transmission path system. In terms of the longitudinal force transmission path, the chassis system forms a complete longitudinal load-bearing chain consisting of the rear body 13 of the front longitudinal beam, the engine compartment connecting plate 14, the front floor sill beam 11, and the rear floor longitudinal beam 16. After receiving the impact force from the front of the engine compartment, the rear body 13 of the front longitudinal beam smoothly introduces the load to the front floor sill beams 11 on both sides via the four-sided lap welds of the engine compartment connecting plate 14. The front floor sill beam 11, with its high bending stiffness provided by CR980 / 1300HS hot-formed high-strength steel and a closed cross-section cavity of approximately 58mm × 89mm, efficiently transmits the impact force longitudinally to the rear floor longitudinal beam 16, and then distributes it to the rear of the vehicle via the rear floor assembly frame. The entire longitudinal force transmission path is continuous and uninterrupted, effectively preventing the accumulation of impact force in the front floor area, which could lead to compression deformation of the passenger compartment.

[0114] In terms of the lateral force transmission path, the chassis system forms a complete lateral load-bearing chain consisting of the door ring body 15, the front seat front crossbeam 3 / front seat rear crossbeam 5, the center tunnel body 7, and the opposite side door ring body 15. When the chassis system suffers a side collision or pole impact, the impact force is first applied to the side door ring body 15, and the door ring body 15 bears the lateral crushing force through the closed cross-sectional cavity formed by it and the front floor sill beam 11.

[0115] Simultaneously, the collision force is transmitted through the three-layer plate welding joint at the second flange 202 of the front floor body 2 to the front seat front crossbeam 3 or the front seat rear crossbeam 5, and then laterally transmitted through the crossbeam to the central tunnel body 7 and the central tunnel rear reinforcement plate 12, and finally to the opposite door ring body 15, forming a complete and continuous lateral force transmission channel. Since the front seat front crossbeam 3 is positioned directly opposite the central tunnel rear reinforcement plate 12, the lateral force transmission has no bending path, resulting in extremely high force transmission efficiency. This effectively prevents the door ring from intruding and deforming into the passenger compartment and battery pack area during a side collision, ensuring the safety of the passenger compartment and battery pack.

[0116] Example 3 In a typical embodiment of the present invention, reference is made to Figures 1-15 As shown, a vehicle is a hybrid vehicle, including plug-in hybrid electric vehicles (PHEVs) and range-extended hybrid electric vehicles (REEVs), which are particularly suitable for hybrid SUVs or off-road passenger vehicles that have high requirements for pure electric range, off-road performance and collision safety.

[0117] The vehicle is equipped with the second-generation chassis system and front floor assembly structure. The lower body frame of the vehicle is welded and assembled from four major assemblies: the engine compartment assembly, the front floor assembly structure, the rear floor assembly, and the side door ring assembly.

[0118] The vehicle in this embodiment achieves the following core performance indicators at the vehicle level: pure electric range of over 210km, an improvement of approximately 75% compared to traditional solutions; the bottom ground clearance of the battery pack 20 is raised by approximately 40mm, significantly enhancing the vehicle's off-road performance; the torsional stiffness of the body is increased by approximately 2600N·m / deg compared to the traditional front floor longitudinal beam solution; and it fully meets the requirements of collision, pole impact, and collision safety regulations.

[0119] like Figure 3 As shown, the vehicle's lower body frame structure in this embodiment is welded and assembled from four major assemblies: the engine compartment assembly, the front floor assembly structure, the rear floor assembly, and the side door ring assembly. The assemblies are connected by multi-face lap welding to form a highly integrated closed frame system.

[0120] The engine compartment assembly is located in front of the front floor assembly structure. Its main components include the rear body 13 of the front longitudinal beam, the engine compartment connecting plate 14, and the subframe connecting plate 18. The rear body 13 of the front longitudinal beam is the rear structural component of the engine compartment longitudinal beam. Its front end is connected to the front longitudinal beam of the engine compartment, and its rear end extends to the front edge of the front floor area. The subframe connecting plate 18 is located at the lateral center of the bottom of the engine compartment and is arranged along the lateral Y direction of the vehicle body. Its rear end flange fits and overlaps with the lower front surface of the front floor body 2 and is fixedly connected by resistance spot welding. It is used to provide an installation interface for the front chassis subframe and bear the vertical, longitudinal, and lateral dynamic loads from the front suspension system. The engine compartment connecting plate 14 is symmetrically arranged on the left and right sides of the subframe connecting plate 18, extending along the longitudinal X direction of the vehicle body. The front end of the engine compartment connecting plate 14 is lap-welded to the rear end of the rear body 13 of the front longitudinal beam, and the rear end is welded to the front end of the front floor sill beam 11 in a four-sided lap joint manner, and continuous resistance spot welding is applied to each side, thereby forming a high-strength multi-sided welded joint at the junction of the engine compartment and the front floor, which enhances the overall connection rigidity at the junction and ensures that the collision load in the engine compartment area can be smoothly and without interruption introduced into the closed cavity section of the front floor sill beam 11.

[0121] The rear floor assembly is located behind the front floor assembly structure. Its main components include a rear floor connecting plate 19 and a rear floor longitudinal beam 16. The rear floor connecting plate 19 is arranged along the transverse Y direction of the vehicle body. Its front end flange overlaps with the rear lower surface of the front floor body 2 and is fixed by spot welding. Its rear end overlaps and is welded to the rear floor panel of the rear floor assembly, serving as a transitional connection between the front and rear floor assemblies. The rear floor longitudinal beam 16 is symmetrically arranged on the left and right sides of the rear floor connecting plate 19 and extends along the longitudinal X direction of the vehicle body. The front end of the rear floor longitudinal beam 16 is welded to the rear end of the front floor sill beam 11 in a four-sided overlap manner. The rear floor longitudinal beam 16 extends longitudinally rearward, bearing the collision load transmitted from the front floor sill beam 11 and further distributing it to the rear floor assembly frame, while also providing an installation interface for the rear chassis suspension system.

[0122] The side door ring assembly includes door ring bodies 15 arranged symmetrically on the left and right. The inner side of the door ring body 15 is welded to the outer flange of the front floor sill beam 11, forming a closed rectangular cavity of approximately 58mm × 89mm. The side of the door ring body 15 is welded to the first flange 201 of the front floor body 2 to meet the coating sealing requirements. The upper surface of the door ring body 15 is overlapped with the second flange 202 of the front floor body 2 and the end connecting plate flange of the front seat front crossbeam 3 (or the front seat rear crossbeam 5) to form a three-layer plate welded structure.

[0123] On the outer side of the overlap node between the rear end of the front floor sill beam 11 and the rear floor longitudinal beam 16, the rear section 17 of the sill is overlapped and welded to the rear end of the front floor sill beam 11 and the door ring body 15. This ensures the continuity of the cross-section of the closed section cavity in the sill area at the junction of the front and rear floors, effectively avoiding stress concentration and local instability caused by abrupt changes in cross-section. Through the overall welding of the above four assemblies, the engine compartment assembly, the front floor assembly structure, the rear floor assembly, and the side door ring assembly are integrated into one, constructing a complete and high-rigidity vehicle lower body frame structure.

[0124] The battery pack 20 is positioned within a frame space between the two front floor sill beams 11. This frame space is enclosed by the two front floor sill beams 11, the front engine compartment connecting plate 14 area, and the rear floor connecting plate 19 area. Since this embodiment completely eliminates the traditional front floor longitudinal beams, the frame space is maximized in both the lateral and longitudinal directions. The lateral dimension of the battery pack 20 fully utilizes the entire clear width between the two front floor sill beams 11, and the longitudinal dimension fully utilizes the entire clear length between the engine compartment connecting plate 14 and the rear floor connecting plate 19. Compared to traditional battery pack arrangements limited by the front floor longitudinal beams, the usable volume of the battery pack 20 is significantly increased, raising the pure electric range of the hybrid vehicle from approximately 120km in the traditional scheme to over 210km.

[0125] The battery pack 20 is embedded within the frame space, and the height of its bottom mounting surface is determined by the bottom surface of the front floor sill beam 11. Since the front floor sill beam 11 is located on the side of the vehicle, its bottom surface height is essentially the same as the bottom height of the side sill. Compared to the traditional method of hanging the battery pack under the front floor longitudinal beam, the bottom of the battery pack 20 is raised approximately 40mm above the ground. This structural elevation significantly increases the vehicle's minimum ground clearance, effectively enhancing the hybrid SUV or off-road vehicle's ability to pass through complex road conditions, while also greatly reducing the safety risk of the battery pack's bottom being scraped or bumped.

[0126] The rigid integrated connection between the battery pack 20 and the vehicle body frame allows the high-strength shell of the battery pack 20 to participate in the overall stress of the vehicle chassis. Together with the front floor sill beam 11, it forms a more complete lower body stress frame, which further enhances the deformation resistance of the overall chassis frame under frontal and side collision conditions and also makes an important contribution to improving the torsional stiffness of the vehicle.

[0127] Compared to vehicles using a traditional front floor longitudinal beam design, the vehicle described in this embodiment achieves comprehensive improvements in range, off-road capability, collision safety, body rigidity, lightweighting, and sealing performance. Regarding range, the traditional design, due to the front floor longitudinal beam occupying battery placement space, limits the battery pack volume, typically resulting in a pure electric range of only about 120km. In contrast, by eliminating the front floor longitudinal beam, the battery pack 20 can fully utilize the entire frame space between the two front floor sill beams 11, increasing the pure electric range to over 210km, an improvement of more than 75%.

[0128] In terms of off-road capability, the traditional solution hangs the battery pack at the bottom of the longitudinal beam, resulting in a serious lack of minimum ground clearance for the entire vehicle. The solution of this invention raises the ground clearance of the bottom of the battery pack 20 by about 40mm, which greatly enhances the vehicle's ability to pass through complex road conditions and off-road scenarios, while significantly reducing the safety risk of scraping and damage to the bottom of the battery pack.

[0129] In traditional solutions, the longitudinal force transmission path breaks down if the front floor longitudinal beam is removed. The solution of this invention reconstructs a high-rigidity longitudinal force transmission path by lap welding the front floor sill beam 11 to the engine compartment connecting plate 14 and the rear floor longitudinal beam 16 on all four sides. It also constructs a complete lateral force transmission channel through the front seat crossbeam assembly and the central tunnel assembly. CAE analysis verifies that the torsional stiffness of the vehicle body is increased by about 2600 N·m / deg compared to the traditional solution, fully meeting the national standard collision, pole impact and collision safety regulations.

[0130] The vehicle solution of this invention takes into account the development needs of both two-wheel drive and four-wheel drive PHEVs, meets the requirements of platform-based development, and reduces the overall development cost. It is particularly suitable for hybrid SUVs and off-road passenger vehicles that have high requirements for range, off-road capability, and collision safety.

[0131] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A front floor assembly structure, characterized by, include: The front floor sill beams are located on both sides of the front floor body. The front floor sill beams are connected to the door ring body and the front floor body respectively by flange overlap to form a closed cross-section cavity. The front end of the front floor sill beam overlaps with the engine compartment connecting plate and the rear end overlaps with the rear floor longitudinal beam to form a complete longitudinal force transmission path. Battery pack mounting points are provided on the front floor sill beams, and a frame space for installing the battery pack is formed between the two front floor sill beams. The front floor sill beam and the engine compartment connecting plate are welded together on four sides, and the front floor sill beam and the rear floor longitudinal beam are welded together on four sides.

2. The front floor assembly structure of claim 1, wherein, The front floor sill beam includes a left front floor sill beam and a right front floor sill beam. A battery pack reinforcing plate is provided on the side of the front floor sill beam near the closed cross-section cavity, and a nut for installing the battery pack is provided on the battery pack reinforcing plate.

3. The front floor assembly structure of claim 2, wherein, Both the left front floor sill beam and the right front floor sill beam have an L-shaped cross-section structure.

4. The front floor assembly structure of claim 3, wherein, The L-shaped cross-section structure is welded to the door ring body and the front floor body through flanges to form a closed cross-section cavity.

5. The front floor assembly structure of claim 1, wherein, The front floor body is provided with front floor cover plates on both sides of the front end; the front floor body is also provided with a front seat crossbeam assembly, and the front floor body adopts a partial secondary flange structure in the overlapping area between the front seat crossbeam assembly and the front floor body.

6. The front floor assembly structure of claim 5, wherein, The partial secondary flange structure includes a first flange and a second flange. The first flange overlaps with the side of the door ring body; the second flange overlaps with the upper surface of the door ring body, and together with the flange of the front seat crossbeam assembly, they form a three-layer plate welded structure.

7. The front floor assembly structure according to claim 6, characterized in that, The three-layer welded structure is formed by welding the upper surface of the door ring body, the second flange of the front floor body, and the flange of the front seat crossbeam assembly together.

8. The front floor assembly structure according to claim 7, characterized in that, The front seat crossbeam assembly includes a front seat front crossbeam and a front seat rear crossbeam; The front crossbeam and the rear crossbeam of the front seat are both overlapped on the front floor body and welded to the center channel assembly. The two ends of the front crossbeam and the rear crossbeam of the front seat are respectively overlapped and welded to the second flange through flanges.

9. The front floor assembly structure according to claim 8, characterized in that, The central channel assembly is located in the middle of the front floor body and includes a central channel body, a central channel front reinforcing plate, a central channel rear reinforcing plate, and a central channel upper cover plate. The central channel front reinforcing plate and the central channel rear reinforcing plate are respectively welded to the front end and the middle of the central channel body, and the central channel upper cover plate is welded to the top of the central channel body.

10. The front floor assembly structure according to claim 9, characterized in that, Both the front crossbeam and the rear crossbeam of the front seat are U-shaped cross-section structural components. The rear crossbeam of the front seat is equipped with a seat mounting bracket. The front crossbeam of the front seat is positioned directly opposite the central channel body and the rear reinforcing plate of the central channel to form a complete force transmission channel structure.

11. The front floor assembly structure according to claim 9, characterized in that, The front seat rear crossbeam is an integrated crossbeam structure that runs through the width of the vehicle body and is welded to the front floor body and the center tunnel body.

12. The front floor assembly structure according to claim 11, characterized in that, The rear crossbeam of the front seat is welded with a rear crossbeam reinforcing plate. The top surface of the rear crossbeam reinforcing plate is provided with a groove rib, and a cavity is formed between the top surface of the groove rib and the top surface of the rear crossbeam of the front seat.

13. The front floor assembly structure according to claim 1, characterized in that, The front floor body also includes a front floor reinforcement plate, which is welded to the rear side of the front floor body to reinforce the local rigidity of the front floor body.

14. The front floor assembly structure according to claim 2, characterized in that, The front floor body is welded to the engine compartment assembly, the rear floor assembly, and the door ring body to form a complete lower vehicle frame structure.

15. The front floor assembly structure according to claim 14, characterized in that, The engine compartment assembly includes a subframe connecting plate, which is welded to the front end of the front floor body. The engine compartment connecting plate is located on both sides of the subframe connecting plate.

16. The front floor assembly structure according to claim 15, characterized in that, The rear floor assembly includes a rear floor connecting plate that overlaps and connects to the rear side of the front floor body, and the rear floor longitudinal beams are located on both sides of the rear floor connecting plate.

17. The front floor assembly structure according to claim 14, characterized in that, The lower body frame structure has a battery pack mounting point at the bottom front end; the bracket on the side of the battery pack is connected to the nut on the battery pack reinforcing plate by a fastening connector.

18. A chassis system, characterized in that, The chassis system includes the front floor assembly structure as described in any one of claims 1-17.

19. A vehicle, characterized in that, The system includes an engine compartment assembly, a rear floor assembly, a door ring body, and a front floor assembly structure as described in any one of claims 1-17. The front ends of the front floor sill beams on both sides of the front floor body are lap-welded to the engine compartment connecting plate, the rear ends of the front floor sill beams are lap-welded to the rear floor longitudinal beams, and the front floor sill beams are lap-welded to the door ring body, forming a complete vehicle body force transmission path frame.

20. The vehicle according to claim 19, characterized in that, The vehicle is a hybrid model. A battery pack is arranged in the frame space between the front floor sill beams on both sides of the front floor body. The battery pack is connected to the vehicle body through the battery pack mounting point on the front floor sill beam.

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