Vehicle body threshold structure

Abstract

The invention belongs to the technical field of automobile production, and provides an automobile body doorsill structure which comprises a front floor assembly, a steel cross beam assembly and an inner doorsill assembly. Inner doorsill assemblies are arranged on the two sides of the automobile body of the front floor assembly; the steel cross beam assembly is mounted between a vehicle body of a front floor assembly and an inner doorsill assembly through a cross beam bracket; the steel cross beam assembly is composed of a first steel cross beam body and a second steel cross beam body. According to the vehicle body doorsill structure, the steel cross beam assembly is arranged and composed of the first steel cross beam body and the second steel cross beam body, the first steel cross beam body and the second steel cross beam body are made of materials through the high-strength HC820 / 1180DP steel rolling forming and tailor-welding technology, and a multi-grid cavity is formed in the steel cross beam assembly; the purposes of absorbing energy and resisting bending deformation of the doorsill assembly are achieved under the column collision working condition, meanwhile, the cost of the high-strength HC820 / 1180DP steel is lower than that of extruded aluminum, and the cost reducing and efficiency increasing effects of the vehicle body doorsill structure are guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of automotive manufacturing technology, and specifically relates to a vehicle body door sill structure. Background Technology

[0002] In today's booming automotive industry, safety performance remains one of the most important factors for consumers when purchasing a car. A car not only needs a dynamic appearance and powerful performance, but also a rock-solid body structure to build a "lifeline" for drivers and passengers. Among the body structure, the door sill, a seemingly inconspicuous component, actually plays a crucial role and can be called the "invisible guardian" of car safety.

[0003] The door sill is a crucial structural component connecting the car door to the bottom of the vehicle body. From the outside, it may just appear as a simple line below the door, but within the vehicle's structure, it acts like a pillar, bearing immense pressure and impact. In a side collision, the door sill is the first point of impact, needing to withstand the enormous force from the colliding object and effectively distribute this force to other parts of the vehicle body, thereby protecting the safety of the occupants.

[0004] In existing technologies, during a side pillar collision, the overlap between the pillar and the vehicle body is small, resulting in extremely high local stress on the inner and outer panels of the sill. This leads to significant velocity and depth of the pillar penetrating the vehicle body, causing excessive occupant injuries. Therefore, it is necessary to add structural components inside the sill to enhance its bending resistance and absorb energy. Existing technologies mostly use... Figure 1 The multi-cell extruded aluminum profile shown is used as a structural component to reduce the intrusion speed and depth of the column. Although the multi-cell extruded aluminum profile can meet the performance requirements for column collision safety, extruded aluminum is about twice the price of steel. In the current environment where the automotive industry needs to reduce costs and increase efficiency, it is urgent to find a low-cost alternative to extruded aluminum.

[0005] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a vehicle sill structure, comprising: a front floor assembly, a steel crossbeam assembly, and an inner sill assembly; the front floor assembly has inner sill assemblies on both sides of the vehicle body; the steel crossbeam assembly is installed between the front floor assembly and the inner sill assembly via a crossbeam bracket; the steel crossbeam assembly is composed of a first steel crossbeam body and a second steel crossbeam body.

[0007] Furthermore, the steel crossbeam body is composed of a first crossbeam plate, with the two ends of the first crossbeam plate being the vehicle body end and the free end, respectively; the vehicle body end and the free end are asymmetrically compound bent, and the bending points are all roll-formed.

[0008] Furthermore, the free end of the first crossbeam plate is first bent upward to form a first bending surface, which is vertical. Then, it is bent towards the body end of the first crossbeam plate to form a second bending surface, with a bending angle of a first R angle. It is then bent downward to form a third bending surface, with the first and third bending surfaces arranged in parallel. The end of the third bending surface is turned outward to form an outer buckle, which overlaps with the top of the first crossbeam plate. The first crossbeam plate, the first bending surface, the second bending surface, and the third bending surface form a first cavity.

[0009] Furthermore, the body end of the first crossbeam plate is bent upward to form a fourth bending surface, and the bending angle is a second R angle. It is then bent towards the third bending surface to form a fifth bending surface. The fifth bending surface and the bottom horizontal plate of the first crossbeam plate are parallel to each other. The end of the fifth bending surface is turned inward to form a first inner buckle, which is locked to the vertical side wall of the third bending surface. The first crossbeam plate, the fourth bending surface, the fifth bending surface and the third bending surface form a second cavity.

[0010] Furthermore, the second bending surface is composed of an inclined transition surface and a first horizontal surface; the inclined transition surface is bent in a wedge shape, and the angle of the first R angle is between 105° and 110°; one end of the inclined transition surface is connected to the first bending surface, and the other end is bent to form the first horizontal surface, which is parallel to the bottom surface of the first crossbeam plate.

[0011] Furthermore, the cross-section of the fourth bending surface is a Z-shaped cross-section structure, and the angle of the second R angle is between 80° and 85°.

[0012] Furthermore, the second steel beam body is composed of a second beam plate; one end of the second beam plate is first bent upwards to form a sixth bending surface, which is vertical, and then bent towards the other end of the second beam plate to form a seventh bending surface, with a bending angle of a third R angle; the other end of the second beam plate and the end of the seventh bending surface are both turned inwards to form a second inner buckle, and the second inner buckle and the outer wall of the first bending surface are closely connected to each other; the second beam plate, the sixth bending surface, the seventh bending surface and the first bending surface form a third cavity; the bending of the second steel beam body is roll forming.

[0013] Furthermore, the third R angle is 120°-125°; the cross section of the second steel beam body is a right trapezoid.

[0014] Furthermore, the first and second steel beam bodies are connected as a whole by welding at the contact position of the first bending surface and the second inner buckle, forming a three-space steel beam assembly; the bottom end of the steel beam assembly is connected to multiple sets of beam supports by riveting, and the beam supports and the inner sill assembly are spot welded together, with multiple spot welds; the left and right ends of the steel beam assembly are bolted to the inner sill assembly.

[0015] Furthermore, the crossbeam support consists of three sets; the spot welding connection points between the crossbeam support and the inner sill assembly are five sets.

[0016] Compared with the prior art, the embodiments of the present invention have at least the following advantages: 1. The vehicle sill structure of the present invention is provided with a steel crossbeam assembly, which consists of a steel crossbeam body one and a steel crossbeam body two. Both steel crossbeam body one and steel crossbeam body two are made of high-strength HC820 / 1180DP steel through roll forming and welding process, so that the steel crossbeam assembly can construct a multi-cell cavity, which can absorb energy and resist the bending deformation of the sill assembly in the pole collision condition. At the same time, the cost of high-strength HC820 / 1180DP steel is lower than that of extruded aluminum, ensuring the cost reduction and efficiency improvement of the vehicle sill structure. 2. The first crossbeam plate features an asymmetrical composite bend between its body end and free end, both formed by roll forming. The bends are all arc-shaped. During installation, the body end of the first crossbeam plate is mounted on the front floor assembly. The first crossbeam plate is integrally formed, with both the first and second cavities created by bending. These two cavities provide a supportive, enclosed structure for impact resistance, ensuring the steel crossbeam body's buffering, energy absorption, and bending resistance. The free end of the first crossbeam plate forms an outward-folding flange that overlaps with the top of the first crossbeam plate, while the body end of the first crossbeam plate forms an inward-folding flange. This design ensures that when subjected to impacts from outside the vehicle into the vehicle, the impact is effectively mitigated. When the maximum impact resistance is exceeded, it can flip upwards. It has an inclined transition surface, and the angle of the first R angle is between 105° and 110°. The design of these two features ensures that the outer buckle at the end of the third bending surface can fit snugly against the top of the first crossbeam plate. Secondly, when subjected to an impact from outside the vehicle towards the inside, the inclined transition surface provides a certain degree of bending after the maximum impact resistance is exceeded. When the impact force bends inwards, the collapsing deformation guided by the inclined transition surface will flip upwards, providing axial deformation compensation capability (allowing ±1.2mm thermal expansion and contraction displacement). Furthermore, it absorbs energy during the bending process of the first crossbeam plate due to impact, further reducing the impact of the impact force.

[0017] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a multi-grid extruded aluminum profile in the prior art is shown; Figure 2 A schematic diagram of the vehicle sill structure in an embodiment of the present invention is shown; Figure 3 A schematic diagram of the steel beam assembly in an embodiment of the present invention is shown; Figure 4 An exploded view of the steel beam assembly and beam support in an embodiment of the present invention is shown; Figure 5 A cross-sectional schematic diagram of the steel beam assembly is shown; Figure 6 The energy absorption capacity / displacement curve of the sill reinforcement in a simulated column impact test using a static column compression test is shown.

[0020] In the diagram, 100 is the front floor assembly; 200 is the steel crossbeam assembly; 300 is the inner sill assembly; 400 is the first steel crossbeam body; 500 is the second steel crossbeam body; 600 is the crossbeam support; 401 is the first crossbeam plate; 402 is the first bending surface; 403 is the first radius (R-angle); 404 is the second bending surface; 4041 is the inclined transition surface; 4042 is the first horizontal plane; 405 is the third bending surface; 406 is the outer buckle; 407 is the first cavity; 501 is the fourth bending surface; 502 is the second radius (R-angle); 503 is the fifth bending surface; 504 is the first inner buckle; 505 is the second cavity; 601 is the second crossbeam plate; 602 is the sixth bending surface; 603 is the third radius (R-angle); 604 is the seventh bending surface; 605 is the second inner buckle; and 606 is the third cavity. Detailed Implementation

[0021] The following description provides many different embodiments or examples for implementing various features of the invention. The elements and arrangements described in the specific examples below are only for concise expression of the invention and are merely examples, not intended to limit the invention.

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be added that, in Figure 1 The example shown is a structural component of a vehicle door sill in the prior art, which is a multi-cell extruded aluminum profile that can meet the performance requirements for pole impact safety.

[0024] This invention provides a vehicle door sill structure. Figure 2 and Figure 3 The system includes a front floor assembly 100, a steel crossbeam assembly 200, and an inner sill assembly 300. Inner sill assemblies 300 are located on both sides of the vehicle body of the front floor assembly 100. The steel crossbeam assembly 200 is installed between the vehicle body of the front floor assembly 100 and the inner sill assembly 300 via a crossbeam bracket 600. The steel crossbeam assembly 200 is composed of a first steel crossbeam body 400 and a second steel crossbeam body 500. In existing technologies, during a side pillar collision, due to the small overlap between the pillar and the vehicle body, the local stress on the inner and outer sill plates is very high, and the speed and depth of the pillar intrusion into the vehicle body are very high, leading to excessive occupant injuries. Therefore, it is necessary to add structural components inside the sill to enhance its bending resistance and absorb energy. Existing technologies mostly use... Figure 1 The multi-cell extruded aluminum profile shown is used as a structural component to reduce the intrusion speed and depth of the pillar. Although the multi-cell extruded aluminum profile can meet the performance requirements of pillar impact safety, it is about twice the price of steel. In the current environment where the automotive industry needs to reduce costs and increase efficiency, it is urgent to find a low-cost alternative to extruded aluminum. To this end, the present invention sets up a steel beam assembly 200, which is composed of a steel beam body 1 400 and a steel beam body 2 500. Both the steel beam body 1 400 and the steel beam body 2 500 are made of high-strength HC820 / 1180DP steel through roll forming and welding processes. The steel beam assembly 200 constructs a multi-cell cavity, which can absorb energy and resist the bending deformation of the sill assembly in the case of pillar impact. At the same time, the high-strength HC820 / 1180DP steel is cheaper than extruded aluminum, ensuring the cost reduction and efficiency improvement of the vehicle body sill structure.

[0025] like Figure 5 As shown: The steel crossbeam body 400 is composed of a first crossbeam plate 401, the two ends of the first crossbeam plate 401 are the vehicle body end and the free end, respectively; the vehicle body end and the free end are asymmetrically compound bent, and the bending parts are all roll-formed. The free end of the first crossbeam plate 401 is first bent upward to form a first bending surface 402, which is vertical. Then, it is bent towards the body end of the first crossbeam plate 401 to form a second bending surface 404, with a bending angle of a first R angle 403. It is then bent downward to form a third bending surface 405, with the first bending surface 402 and the third bending surface 405 arranged in parallel. The end of the third bending surface 405 is turned outward to form an outer buckle 406, which is in surface contact with the top of the first crossbeam plate 401. The first crossbeam plate 401, the first bending surface 402, the second bending surface 404, and the third bending surface 405 form a first cavity 407. The body end of the first crossbeam plate 401 is bent upward to form a fourth bending surface 501 with a bending angle of a second R angle 502. It is then bent towards the third bending surface 405 to form a fifth bending surface 503. The fifth bending surface 503 and the bottom horizontal plate surface of the first crossbeam plate 401 are parallel to each other. The end of the fifth bending surface 503 is turned inward to form a first inner buckle 504, which is locked to the vertical side wall of the third bending surface 405. The first crossbeam plate 401, the fourth bending surface 501, the fifth bending surface 503 and the third bending surface 405 form a second cavity 505. During operation, the body end and free end of the first crossbeam plate 401 are asymmetrically bent, both by roll forming, and the bends are all arc-shaped. During the installation process, the body end of the first crossbeam plate 401 is installed on the body of the front floor assembly 100. The first crossbeam plate 401 is integrally formed, and the first cavity 407 and the second cavity 505 are both formed by bending. The existence of the two cavities provides a supportive closed structure for impact resistance, ensuring the buffering, energy absorption and bending resistance of the steel crossbeam body 400. The free end of the first crossbeam plate 401 is turned outward to form an outer buckle 406, which forms a surface contact overlap with the top of the first crossbeam plate 401. The body end of the first crossbeam plate 401 is turned inward to form a first inner buckle 504. The two configurations ensure that when subjected to an impact from outside the vehicle to inside the vehicle, the crossbeam plate can flip upward when the maximum impact force is exceeded.

[0026] like Figure 5As shown: The second bending surface 404 is composed of an inclined transition surface 4041 and a first horizontal surface 4042; the inclined transition surface 4041 is formed by a wedge bend, and the angle of the first R angle 403 is between 105° and 110°; one end of the inclined transition surface 4041 is connected to the first bending surface 402, and the other end is bent to form the first horizontal surface 4042, which is parallel to the bottom surface of the first horizontal beam plate 401; during operation, the inclined transition surface 4041 and the angle of the first R angle 403 being between 105° and 110° ensure that the first horizontal surface 4041 is bent. The outer buckle 406 at the end of the three-bend surface 405 can ensure that the outer buckle 406 can fit on the top of the first crossbeam plate 401, ensuring tightness. Secondly, when subjected to an impact from outside the vehicle towards the inside, due to the setting of the inclined transition surface 4041, it has a certain degree of bending after exceeding the maximum impact resistance. When the impact force bends inward, the collapse deformation guided by the inclined transition surface 4041 will flip upward, which has axial deformation compensation capability (allowing ±1.2mm thermal expansion and contraction displacement). In addition, it absorbs energy during the bending process of the first crossbeam plate 401 due to impact, further reducing the impact of the impact force.

[0027] The fourth bending surface 501 has a Z-shaped cross-section, and the angle of the second R angle 502 is between 80° and 85°. During operation, the fourth bending surface 501 has a Z-shaped cross-section, which firstly adapts to the shape of the front floor assembly 100 body surface, ensuring that the fourth bending surface 501 can fit against the body surface when the steel crossbeam assembly 200 is installed, thereby strengthening the rigidity of the mounting surface (improving NVH performance by 20%-30%). At the same time, it ensures the optimization of the dynamic load transmission path. Because the angle of the second R angle 502 is between 80° and 85°, it can ensure that the end of the fifth bending surface 503 can form an interference fit with the outer wall of the third bending surface 405.

[0028] The steel beam body 500 is composed of a second beam plate 601. One end of the second beam plate 601 is first bent upwards to form a sixth bending surface 602, which is vertical. Then, it is bent towards the other end of the second beam plate 601 to form a seventh bending surface 604, with a bending angle of a third radius 603. The other end of the second beam plate 601 and the end of the seventh bending surface 604 are both turned inwards to form a second inner buckle 605, which is connected to the outer wall of the first bending surface 402. The second beam plate 601, the sixth bending surface 602, the seventh bending surface 604, and the first bending surface 402 form a third cavity 606. The bending of the steel beam body 500 is achieved by roll forming. The third R angle 603 is 120°-125°; the cross section of the steel beam body 2500 is a right trapezoid; During operation, the cross-section of the steel beam body is a right-angled trapezoid, with its vertical dimension gradually increasing from the outside to the inside of the vehicle. At the same time, the moment of inertia of the cross section is optimized to improve bending stiffness. During installation, the right-angled trapezoidal inclined surface of the steel beam body 2500 is on top. When subjected to impact force, the right-angled trapezoidal inclined surface can guide the direction of collapse deformation. At the same time, when the steel beam body 2500 is attached to the steel beam body 1400, a third cavity 606 is formed, making the steel beam assembly 200 form three sealed cavities, further improving impact resistance. The three sealed cavities form a three-level nested structure, establishing a multi-path load transfer mechanism and improving torsional stiffness.

[0029] like Figure 4 As shown: The steel beam body 1 400 and the steel beam body 2 500 are connected as a whole by welding at the contact position of the first bending surface 402 and the second inner buckle 605, forming a three-space steel beam assembly 200; the bottom end of the steel beam assembly 200 is connected to multiple sets of beam supports 600 by riveting, and the beam supports 600 and the inner sill assembly 300 are connected by spot welding, with multiple spot welds; the left and right ends of the steel beam assembly 200 are connected to the inner sill assembly 300 by bolts. The crossbeam support 600 consists of three sets; the spot welding connection positions between the crossbeam support 600 and the inner sill assembly 300 are five sets; During operation, the first and second crossbeam bodies are welded together to form a whole, making the steel crossbeam assembly 200 a complete unit, improving impact resistance. The bottom of the steel crossbeam assembly 200 is connected between the inner sill assembly 300 and the front floor assembly 100 body through multiple sets of crossbeam brackets 600, ensuring installation stability.

[0030] In this embodiment, Figure 6 The diagram shows the energy absorption capacity / displacement curve of the sill reinforcement in a simulated column impact test using a static column compression experiment, where STEEL-1180 represents a rolled steel crossbeam ( Figure 3 LV-6028 represents the original multi-grid extruded aluminum crossbeam ( Figure 1 ), Figure 6 The image shows the force (F, kN) versus displacement (S, mm) curves and the corresponding energy absorption (J) curves for two sets of door sill reinforcements (LV-6028, STEEL-1180), compared to the original multi-grid extruded aluminum crossbeam. Figure 1 ) and rolled steel crossbeams ( Figure 3 Performance differences; The force-displacement curve has the following characteristics: LV - 6028 - Force: The force increases with displacement starting from 0mm, showing a trend of "rapid increase → steady → rapid increase again". The maximum force (Max) is 276.713kN, corresponding to a displacement of about 90mm. The overall force value is higher than STEEL-1180-Force. STEEL - 1180 - Force: The force increases with displacement in a trend of "slowly rising → steady → rapidly rising". The maximum force (Max) is 235.747kN, corresponding to a displacement of about 90mm. The force value is lower than LV-6028-Force.

[0031] The characteristics of the energy absorption curve are as follows: LV - 6028 - Energy: The energy absorption shows a trend of "slowly rising → steady → rapidly rising" as the displacement increases. The maximum energy absorption (Max) is 17948.8J, corresponding to a displacement of about 90mm. The energy absorption is lower than that of STEEL-1180- Energy.

[0032] STEEL - 1180 - Energy: The energy absorption shows a trend of "slowly rising → steady → rapidly rising" with the increase of displacement. The maximum energy absorption (Max) is 18969.1J, corresponding to a displacement of about 90mm. The energy absorption is significantly higher than that of LV-6028-Energy.

[0033] Force comparison: LV - 6028 - Force has a higher maximum force, indicating that the reinforcement can withstand a higher load during a collision; STEEL - 1180 - Force has a slightly lower maximum force, but the force curve is more stable, which may indicate more uniform deformation at low load stages; Energy absorption comparison: STEEL - 1180 - Energy absorbs far more energy than LV - 6028 - Energy, indicating that this reinforcement can absorb impact energy more efficiently in a collision, reducing the damage to the vehicle / occupants. The simulation results show that the energy absorption capacity / displacement curve of the steel crossbeam assembly 200 is better than that of the multi-grid extruded aluminum. In terms of weight and cost, the multi-grid extruded aluminum weighs 6.5 kg and costs 280 yuan, while the multi-grid steel crossbeam weighs 10.6 kg and costs 170 yuan. Due to the double side sills of the whole vehicle, the cost reduction per vehicle is 220 yuan.

[0034] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or connections that allow for communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of multiple components or the interaction between multiple components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] It should be understood that all terms used to indicate orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as a limitation of the present invention.

[0037] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vehicle sill structure, characterized in that, It includes a front floor assembly (100), a steel crossbeam assembly (200), and an inner sill assembly (300); the front floor assembly (100) is provided with inner sill assemblies (300) on both sides of the vehicle body; the steel crossbeam assembly (200) is installed between the front floor assembly (100) and the inner sill assembly (300) via a crossbeam bracket (600); the steel crossbeam assembly (200) is composed of a first steel crossbeam body (400) and a second steel crossbeam body (500).

2. The vehicle sill structure according to claim 1, characterized in that, The steel crossbeam body (400) is composed of a first crossbeam plate (401), with the two ends of the first crossbeam plate (401) being the vehicle body end and the free end, respectively; the vehicle body end and the free end are asymmetrically compound bent, and the bending points are all roll-formed.

3. The vehicle sill structure according to claim 2, characterized in that, The free end of the first crossbeam plate (401) is first bent upward to form a first bending surface (402), which is vertical. Then it is bent towards the body end of the first crossbeam plate (401) to form a second bending surface (404), and the bending angle is a first R angle (403). It is then bent downward to form a third bending surface (405), and the first bending surface (402) and the third bending surface (405) are arranged in parallel. The end of the third bending surface (405) is turned outward to form an outer buckle (406), and it forms a surface contact overlap with the top of the first crossbeam plate (401). The first crossbeam plate (401), the first bending surface (402), the second bending surface (404) and the third bending surface (405) form a first cavity (407).

4. The vehicle sill structure according to claim 3, characterized in that, The body end of the first crossbeam plate (401) is bent upward to form a fourth bending surface (501) with a bending angle of the second R angle (502). It is then bent towards the third bending surface (405) to form a fifth bending surface (503). The fifth bending surface (503) and the bottom horizontal plate of the first crossbeam plate (401) are parallel to each other. The end of the fifth bending surface (503) is turned inward to form a first inner buckle (504), which is locked to the vertical side wall of the third bending surface (405). The first crossbeam plate (401), the fourth bending surface (501), the fifth bending surface (503) and the third bending surface (405) form a second cavity (505).

5. The vehicle sill structure according to claim 3, characterized in that, The second bending surface (404) is composed of an inclined transition surface (4041) and a first horizontal surface (4042); the inclined transition surface (4041) is bent in a wedge shape, and the angle of the first R angle (403) is between 105° and 110°; one end of the inclined transition surface (4041) is connected to the first bending surface (402), and the other end is bent to form the first horizontal surface (4042), and the bottom surface of the first horizontal surface (4042) and the first crossbeam plate (401) are parallel to each other.

6. The vehicle sill structure according to claim 4, characterized in that, The cross-section of the fourth bending surface (501) is a Z-shaped cross-section structure, and the angle of the second R angle (502) is between 80° and 85°.

7. The vehicle sill structure according to claim 3, characterized in that, The steel beam body 2 (500) is composed of a second beam plate (601); one end of the second beam plate (601) is first bent upward to form a sixth bending surface (602), the sixth bending surface (602) is in a vertical state, and then bent towards the other end of the second beam plate (601) to form a seventh bending surface (604), and the bending angle is a third R angle (603); the other end of the second beam plate (601) and the end of the seventh bending surface (604) are both turned inward to form a second inner buckle (605), and the second inner buckle (605) and the outer wall of the first bending surface (402) are closely connected to each other; the second beam plate (601), the sixth bending surface (602), the seventh bending surface (604) and the first bending surface (402) form a third cavity (606); the bending of the steel beam body 2 (500) is roll forming.

8. The vehicle sill structure according to claim 7, characterized in that, The third R angle (603) is 120°-125°; the cross section of the steel beam body two (500) is a right trapezoid.

9. The vehicle sill structure according to claim 4, characterized in that, The first steel beam body (400) and the second steel beam body (500) are connected as a whole by welding at the contact position of the first bending surface (402) and the second inner buckle (605) to form a three-space steel beam assembly (200).

10. The vehicle sill structure according to claim 9, characterized in that, The bottom end of the steel beam assembly (200) is connected to multiple sets of beam supports (600) by riveting. The beam supports (600) and the inner sill assembly (300) are connected by spot welding. There are multiple spot welds. The left and right ends of the steel beam assembly (200) are connected to the inner sill assembly (300) by bolts.

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