Heavy truck step mounting structure and assembling method thereof

Abstract

The invention provides a heavy truck step mounting structure which comprises a front lower protection assembly, a left step framework assembly and a right step framework assembly, a front lower protection mounting plate and a step mounting plate are arranged on the front lower protection assembly, and the front lower protection assembly is connected with a frame casting through the front lower protection mounting plate. The left step framework assembly and the right step framework assembly are connected with the step mounting plate, the left step framework assembly and the right step framework assembly are integrated on the front lower protection assembly, and the existing structure and high strength of the front lower protection assembly are utilized, so that the light weight of the step framework assembly is met, and the assembly precision of the step and the front protection is improved; and a front bumper connecting structure in the step framework assembly is connected with a front bumper framework, so that the assembly precision of the step plate and the front bumper is further improved.

Description

A step mounting structure for heavy-duty trucks and its assembly method Technical Field

[0001] This invention belongs to the field of heavy-duty truck body accessories. Specifically, this invention relates to a heavy-duty truck step mounting structure and its assembly method. Background Technology

[0002] The entry step on heavy-duty trucks is a crucial component for drivers and passengers getting on and off the vehicle, providing a platform for safe and reliable entry and exit. Because the entry step must support the safe entry and exit of passengers, its frame strength is paramount. Heavy-duty truck entry step frames often utilize bent-tube type brackets. These brackets primarily consist of connecting steel pipes, frame-end mounting brackets, and step-end mounting brackets. The bent-tube type brackets are mounted on the frame longitudinal beams. The significant gap between the frame longitudinal beams and the step guard plate necessitates a long cantilever structure connection. Due to the amplification characteristic of the cantilever structure, the maximum stress is borne by the frame-end mounting brackets and the connecting steel pipes, which are reinforced with heavy components. The connecting steel pipes are manufactured using a bending process, resulting in poor overall dimensional accuracy. Manufacturing errors in the frame-end mounting brackets are magnified into installation errors at the step end, making assembly precision difficult to control and gap control with the front bumper challenging. Summary of the Invention

[0003] This invention is made to solve the above-mentioned problems, and aims to provide a novel step mounting structure for commercial vehicles and a commercial vehicle that can reduce the self-weight of the step bracket and reduce the difficulty of controlling the gap between it and the front bumper. The step mounting structure and its assembly method for heavy truck vehicles are as follows: To achieve the above objective, the technical solution adopted by this invention is as follows: This invention provides a step mounting structure for heavy truck vehicles, which includes a front lower protection assembly, a left step frame assembly, and a right step frame assembly. The front lower protection assembly is provided with a front lower protection mounting plate and a step mounting plate. The front lower protection assembly is connected to the vehicle frame casting through the front lower protection mounting plate. The left step frame assembly and the right step frame assembly are connected to the step mounting plate.

[0004] The heavy-duty truck step mounting structure provided by the present invention may also have the following features: the front lower protection assembly further includes a front lower protection crossbeam and a crossbeam reinforcing plate, the crossbeam reinforcing plate is respectively disposed at both ends of the front lower protection crossbeam, the front lower protection mounting plate and the step mounting plate are disposed on the crossbeam reinforcing plate, and the front lower protection mounting plate is located inside the step mounting plate.

[0005] The heavy truck step mounting structure provided by the present invention may also have the following features: the front lower protective mounting plate includes a side mounting plate, a side reinforcing plate and a rear reinforcing plate, one side of the rear reinforcing plate is connected to the side mounting plate, the other side of the rear reinforcing plate is connected to the side reinforcing plate, and it is located between the side mounting plate and the side reinforcing plate.

[0006] The heavy-duty truck step mounting structure provided by the present invention may also have the following features: the step mounting plate includes a step frame mounting plate and a first flange and a second flange disposed on the step frame mounting plate. The step frame mounting plate is provided with step frame mounting points. The first flange is located on the upper side, left side and right side of the step frame mounting plate, and the second flange is located on the lower side of the step frame mounting plate. The length of the second flange is longer than the length of the first flange.

[0007] The heavy-duty truck step mounting structure provided by the present invention may also have the following features: the left step frame assembly includes a left step frame longitudinal beam, a left step frame mounting plate assembly, a left step frame front bumper connecting plate, and a left step foot support plate. The left step frame longitudinal beam is connected to the left step frame mounting plate assembly, the left step frame mounting plate assembly is connected to the step frame mounting plate, the left step frame front bumper connecting plate is disposed on the left step frame longitudinal beam, and the left step foot support plate is disposed on the left step frame longitudinal beam.

[0008] The heavy-duty truck step mounting structure provided by the present invention may also have the following feature: the left step frame mounting plate assembly includes a first frame mounting plate and a second frame mounting plate, both of which are "L" shaped and are respectively arranged on both sides of the left step frame longitudinal beam.

[0009] The heavy-duty truck step mounting structure provided by the present invention may also have the following features: the right step frame assembly includes a right step frame longitudinal beam, a right step frame mounting plate assembly, a right step frame front bumper connecting plate, and a right step foot support plate. The right step frame longitudinal beam is connected to the right step frame mounting plate assembly, the right step frame mounting plate assembly is connected to the step frame mounting plate, the right step frame front bumper connecting plate is disposed on the right step frame longitudinal beam, and the right step foot support plate is disposed on the right step frame longitudinal beam.

[0010] The heavy-duty truck step mounting structure provided by the present invention may also have the following feature: the right step frame mounting plate assembly includes a third frame mounting plate and a fourth frame mounting plate, both of which are "L" shaped and are respectively arranged on both sides of the right step frame longitudinal beam.

[0011] The heavy-duty truck step mounting structure provided by the present invention may also have the following feature: the right step frame assembly further includes a tilt pump mounting unit, the tilt pump mounting unit includes a tilt pump mounting bracket and a tilt controller mounting bracket connected to the tilt pump mounting bracket, the tilt pump mounting bracket is disposed on the right step frame longitudinal beam and located at the rear end of the right step frame longitudinal beam.

[0012] The present invention also provides an assembly method for the above-mentioned heavy truck vehicle step mounting structure, characterized by the following steps: Step S1, assembling the crossbeam reinforcing plate and the front lower protective crossbeam, and pre-installing the front lower protective mounting plate and the step mounting plate on the crossbeam reinforcing plate to form the front lower protective assembly; Step S2, pre-installing the left and right step frame assemblies with their respective frame longitudinal beams, mounting plate groups, front bumper connecting plates, and step support plates; Step S3, fixing the front lower protective assembly to the frame casting through the front lower protective mounting plate; Step S4, connecting and fixing the left and right step frame assemblies to the corresponding step mounting plates on the front lower protective assembly through their respective mounting plate groups; Step S5, installing the tilt pump mounting bracket and the tilt controller mounting bracket at the rear end of the right step frame longitudinal beam to complete the overall assembly. The technical advantages of this invention are as follows: The heavy-duty truck step mounting structure provided by this invention includes a front lower protection assembly, a left step frame assembly, and a right step frame assembly. The front lower protection assembly is provided with a front lower protection mounting plate and a step mounting plate. The front lower protection assembly is connected to the vehicle frame casting through the front lower protection mounting plate. The left step frame assembly and the right step frame assembly are connected to the step mounting plate. The left step frame assembly and the right step frame assembly are integrated on the front lower protection assembly. By utilizing the existing structure and high strength of the front lower protection assembly, the lightweighting of the step frame assembly is achieved while improving the assembly accuracy of the step and the front bumper. The front bumper connection structure inside the step frame assembly is connected to the front bumper frame, further improving the assembly accuracy of the step plate and the front bumper. Attached Figure Description

[0013] This specification includes the following figures, which are as follows: Figure 1 is a structural schematic diagram of the heavy-duty truck step mounting structure in an embodiment of the present invention; Figure 2 is a schematic diagram of the connection between the heavy-duty truck step mounting structure and the frame casting and front bumper in an embodiment of the present invention; Figure 3 is a structural schematic diagram of the step mounting plate in an embodiment of the present invention; Figure 4 is a structural schematic diagram of section AA in Figure 3; Figure 5 is a structural schematic diagram of the left step frame assembly in an embodiment of the present invention (first); Figure 6 is a structural schematic diagram of the left step frame assembly in an embodiment of the present invention (second); Figure 7 is a structural schematic diagram of the right step frame assembly in an embodiment of the present invention.

[0014] The components marked in the diagram are: frame casting-1, front bumper-2, front lower protection assembly-10, front lower protection mounting plate-11, side mounting plate-111, side reinforcement plate-112, rear reinforcement plate-113, step mounting plate-12, step frame mounting plate-121, first flange-122, second flange-123, step frame mounting point-124, front lower protection crossbeam-13, crossbeam reinforcement plate-14, left step frame assembly-20, left step frame longitudinal beam-21, left step frame mounting plate assembly-22. 1. First frame mounting plate - 221; 2. Second frame mounting plate - 222; 3. Left step frame front support connecting plate - 23; 4. Left step foot support plate - 24; 5. Right step frame assembly - 30; 6. Right step frame longitudinal beam - 31; 7. Right step frame mounting plate assembly - 32; 8. Third frame mounting plate - 321; 9. Fourth frame mounting plate - 322; 10. Right step frame front support connecting plate - 33; 11. Right step foot support plate - 34; 12. Tilting pump mounting unit - 35; 13. Tilting pump mounting bracket - 351; 14. Tilting controller mounting bracket - 352. Detailed Implementation

[0015] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation.

[0016] Figure 1 is a structural schematic diagram of the heavy truck vehicle step mounting structure in an embodiment of the present invention; Figure 2 is a schematic diagram of the connection between the heavy truck vehicle step mounting structure and the frame casting and front bumper in an embodiment of the present invention.

[0017] As shown in Figures 1 and 2, the present invention provides a step mounting structure for heavy-duty trucks, including a front lower protection assembly 10, a left step frame assembly 20, and a right step frame assembly 30. The front lower protection assembly 10 is provided with a front lower protection mounting plate 11 and a step mounting plate 12. The front lower protection assembly 10 is connected to the frame casting 1 through the front lower protection mounting plate 11. The left step frame assembly 20 and the right step frame assembly 30 are connected to the step mounting plate 12, integrating the left step frame assembly 20 and the right step frame assembly 30 onto the front lower protection assembly 10. The front lower protection assembly 10 serves as the core load-bearing base and integrated mounting carrier of the entire structure, simultaneously undertaking the functions of front lower protection and step mounting, thus achieving functional integration, structural integration, and unified installation standards. By utilizing the existing structure and high strength of the front lower bumper assembly 10, both the lightweight design of the step frame assembly and the improved assembly precision of the step and the front bumper are achieved. The front bumper connection structure within the step frame assembly connects to the front bumper frame, further enhancing the assembly precision of the step plate and the front bumper 2. Simultaneously, front bumper connection structures are installed inside both the left and right step frame assemblies 20 and 30, respectively positioning and connecting to the front bumper 2. This dual positioning reference further improves the assembly precision and connection stability of the step plate and the front bumper 2, reducing issues such as loosening, abnormal noise, and deformation caused by vibration during vehicle operation, thereby improving the overall vehicle reliability and driving experience.

[0018] The front lower protection assembly 10 integrates a front lower protection mounting plate 11 and a step mounting plate 12, allowing the front lower protection assembly 10 to be fixedly connected to the frame casting 1 via the front lower protection mounting plate 11, forming a rigid connection with the frame and ensuring the stability and reliability of the overall structure during vehicle operation. The left step frame assembly 20 and the right step frame assembly 30 are fixedly connected to the step mounting plate 12 via corresponding connection structures, thereby directly integrating the left and right step structures onto the front lower protection assembly 10, eliminating the need for additional independent brackets, transition brackets, or scattered mounting points, and achieving an integrated design of the step structure and the front lower protection structure.

[0019] The front lower protection assembly 10 also includes a front lower protection crossbeam 13 and a crossbeam reinforcing plate 14. The crossbeam reinforcing plate 14 is respectively disposed at both ends of the front lower protection crossbeam 13. The front lower protection mounting plate 11 and the step mounting plate 12 are disposed on the crossbeam reinforcing plate 14. The front lower protection mounting plate 11 is located inside the step mounting plate 12. Both the front lower protection mounting plate 11 and the step mounting plate 12 are fixedly disposed on the crossbeam reinforcing plate 14. The front lower protection mounting plate 11 is located inside the step mounting plate 12, close to the vehicle's central symmetry plane, while the step mounting plate 12 is located outside, close to the vehicle's side. The two are arranged in front-to-back and inside-outside layers on the crossbeam reinforcing plate 14, without interfering with each other. The installation position is clear and the assembly space is sufficient.

[0020] The front lower protection crossbeam 13 is a rectangular straight-seam welded steel pipe used to support and connect various components. It is the core component of the front lower protection and has advantages such as high section modulus, good bending performance, large torsional stiffness, and strong load-bearing capacity. During vehicle operation, it can effectively withstand frontal impact loads, lateral loads, and step loads transmitted by the steps. It is the core load-bearing component of the front lower protection assembly 10 and is used to realize the load-bearing, connection, and force transmission of various accessories.

[0021] The cross-section of the beam reinforcement plate 14 is "]" shaped, and it is a semi-enclosed structure located at the left and right ends of the front lower protective beam 13. It wraps around the outer, upper and lower sides of the left and right ends of the front lower protective beam 131. It is firmly connected to the front lower protective beam 13 by welding, which improves the local strength at the end and provides a stable installation foundation for the front lower protective mounting plate 11 and the step mounting plate 12.

[0022] The front lower protective mounting plate 11 includes a side mounting plate 111, a side reinforcing plate 112, and a rear reinforcing plate 113. One side of the rear reinforcing plate 113 is connected to the side mounting plate 111, and the other side of the rear reinforcing plate 113 is connected to the side reinforcing plate 112, located between the side mounting plate 111 and the side reinforcing plate 112. The side mounting plate 111 and the side reinforcing plate 112 are opposite to each other, and the rear reinforcing plate 113 is located in the groove formed by the side mounting plate 111 and the side reinforcing plate 112. The front lower protective mounting plate 11 has an overall box-shaped structure with an upward opening, located inside the front lower protective beam 13 along its length, and connected to the upper and rear surfaces, used to connect the front lower protective assembly 10 and the frame casting 4. The box-shaped structure of the front lower protective mounting plate 11 has extremely high structural rigidity and deformation resistance, which can effectively disperse the load from the front lower protective beam 13 and stably transfer it to the frame casting 1, avoiding excessive local stress. The front lower protection mounting plate 11 is located inside the front lower protection crossbeam 13 along its length. It is welded to the upper and rear surfaces of the front lower protection crossbeam 13 to ensure connection strength and positioning accuracy. Through the front lower protection mounting plate 11, the front lower protection assembly 10 can achieve a firm, precise and reliable connection with the frame casting 1, providing a stable vehicle installation reference for the entire step mounting structure.

[0023] Figure 3 is a structural schematic diagram of the step mounting plate in an embodiment of the present invention; Figure 4 is a structural schematic diagram of section AA in Figure 3. As shown in Figures 3 and 4, the step mounting plate 12 includes a step frame mounting plate 121 and a first flange 122 and a second flange 123 disposed on the step frame mounting plate 121. The step frame mounting plate 121 is provided with step frame mounting points 124. The first flange 122 is located on the upper side, left side and right side of the step frame mounting plate 121, and the second flange 123 is located on the lower side of the step frame mounting plate 121. The length of the second flange 123 is longer than the length of the first flange 122, so that the overall structure of the step mounting plate 12 is a square box structure. Nuts are projected and welded at corresponding positions on the back of the mounting surface of the step frame mounting plate 121. The first flange 122 and the second flange 123 are connected to the lower surface and rear surface of the crossbeam reinforcing plate 14. The longer flange is located at the lower part of the lower surface, providing a mounting plane and mounting point for the left step frame assembly 20 and the right step frame assembly 30. The first flange 122 and the second flange 123 are welded to the lower and rear surfaces of the crossbeam reinforcing plate 14, respectively, forming a stable connection structure with multi-faceted fit and multi-point stress. The longer second flange 123 is located at the lower part of the lower surface, which can provide a larger and more stable mounting surface and mounting point for the left step frame assembly 20 and the right step frame assembly 30, thereby improving installation accuracy and connection strength.

[0024] Through the aforementioned integrated arrangement, this invention fully utilizes the existing high-strength structure and rigidity reserves of the front lower protection assembly 10. While meeting the relevant national regulations regarding the strength, location, and energy absorption characteristics of front lower protection devices, it provides a stable, reliable, and high-strength installation foundation for the step structure. While achieving a lightweight design for the step frame assembly, reducing the number of parts, and lowering material consumption and manufacturing costs, it effectively improves the assembly precision between the step and the front bumper, ensuring uniform gaps and consistent step heights between the step plate and the outer surface of the front bumper, thereby enhancing the overall vehicle appearance and assembly quality.

[0025] Figure 5 is a schematic diagram of the left step frame assembly in an embodiment of the present invention; Figure 6 is a schematic diagram of the left step frame assembly in an embodiment of the present invention.

[0026] As shown in Figures 5 and 6, the left step frame assembly 20 includes a left step frame longitudinal beam 21, a left step frame mounting plate assembly 22, a left step frame front support connecting plate 23, and a left step foot support plate 24. The left step frame longitudinal beam 21 is connected to the left step frame mounting plate assembly 22, the left step frame front support connecting plate 23 is connected to the step frame mounting plate 12, the left step frame front support connecting plate 23 is mounted on the left step frame longitudinal beam 21, and the left step foot support plate 24 is mounted on the left step frame longitudinal beam 21.

[0027] As shown in Figures 5 and 6, the left step frame mounting plate assembly 22 includes a first frame mounting plate 221 and a second frame mounting plate 222. Both the first frame mounting plate 221 and the second frame mounting plate 222 are L-shaped. The L-shaped structure has good torsional and bending resistance, and can stably transmit the stepping load. They are respectively set on both sides of the left step frame longitudinal beam 21 to connect the step frame mounting plate 12 and the left step frame longitudinal beam 21. The long sides of the first frame mounting plate 221 and the second frame mounting plate 222 are welded to the left step frame longitudinal beam 21, and the short sides are used to connect with the step mounting plate 12 to achieve a firm connection between the front lower protection assembly 10 and the left step frame longitudinal beam 21.

[0028] The left step frame longitudinal beam 21 is a rectangular straight-seam welded steel pipe used to support and connect various components. The first frame mounting plate 221 and the second frame mounting plate 222 have an "L"-shaped structure. The long side of the "L" shape of the first frame mounting plate 221 and the second frame mounting plate 222 is connected to the inner and outer sides of the front end of the left step frame longitudinal beam 21, which is used to connect the step mounting plate 14 and the left step frame longitudinal beam 21. The left step frame front bumper connecting plate 23 is located behind the left step frame mounting plate assembly 22 and is connected to the outer side of the left step frame longitudinal beam 21. The outer end of the left step frame front bumper connecting plate 23 is connected to the front bumper 2. Further improve the assembly precision and overall rigidity of the step and front bumper; the left step support plate 24 has an inverted "U" shaped structure. The left step support plate 24 consists of a mounting surface and two flanges. The mounting surface of the left step support plate 24 is perpendicular to the outer side of the left step frame longitudinal beam 21 and is located at the rear end of the left step frame longitudinal beam 21. It is connected to the outer and lower surfaces of the left step frame longitudinal beam 21 to form multi-faceted support. The left step support plate 24 is one of the important components that provides a load-bearing plane and ensures the safe and reliable entry and exit of drivers and passengers. It can withstand large instantaneous impact loads and long-term cyclic loads.

[0029] Figure 7 is a schematic diagram of the right step frame assembly in an embodiment of the present invention.

[0030] As shown in Figure 7, the right step frame assembly 30 includes a right step frame longitudinal beam 31, a right step frame mounting plate assembly 32, a right step frame front support connecting plate 33, and a right step foot support plate 34. The right step frame longitudinal beam 31 is connected to the right step frame mounting plate assembly 32, and the right step frame mounting plate assembly 32 is connected to the step frame mounting plate 12. The right step frame front support connecting plate 33 is mounted on the right step frame longitudinal beam 31, and the right step foot support plate 34 is mounted on the right step frame longitudinal beam 31.

[0031] As shown in Figure 7, the right step frame mounting plate group 32 includes a third frame mounting plate 321 and a fourth frame mounting plate 322. Both the third frame mounting plate 321 and the fourth frame mounting plate 322 are "L" shaped and are respectively set on both sides of the right step frame longitudinal beam 31.

[0032] The right step frame longitudinal beam 31 is a rectangular straight-seam welded steel pipe used to support and connect various components. The third frame mounting plate 321 and the fourth frame mounting plate 322 are "L"-shaped structures. The long sides of the "L" shape of the third frame mounting plate 321 and the fourth frame mounting plate 322 are connected to the inner and outer sides of the front end of the right step frame longitudinal beam 31 to connect the step mounting plate 14 and the right step frame longitudinal beam 31. The right step frame front guard connecting plate 33 is located behind the right step frame mounting plate assembly 32 and is connected to the outer side of the right step frame longitudinal beam 31. The left step frame front guard... The outer end of the connecting plate 23 is connected to the front bumper 2, further improving the assembly accuracy of the step and the front bumper; the right step support plate 34 has an inverted "U" shaped structure. The right step support plate 34 consists of a mounting surface and two flanges. The mounting surface of the right step support plate 34 is perpendicular to the outer side of the right step frame longitudinal beam 31 and is located at the rear end of the right step frame longitudinal beam 31. It is connected to the outer surface and the lower surface of the right step frame longitudinal beam 31. The right step support plate 34 is one of the important components that provides a load-bearing plane and ensures the safe and reliable entry and exit of the vehicle for drivers and passengers.

[0033] As shown in Figure 7, the right step frame assembly 30 also includes a tilt pump mounting unit 35. The tilt pump mounting unit 35 includes a tilt pump mounting bracket 351 and a tilt controller mounting bracket 352 connected to the tilt pump mounting bracket 351. The tilt pump mounting bracket 351 is set on the right step frame longitudinal beam 31 and is located at the rear end of the right step frame longitudinal beam 31, realizing the integrated installation of the step frame with the tilt pump and tilt controller, reducing independent brackets and improving space utilization.

[0034] The tilt pump mounting bracket 351 is composed of a mounting surface and two flanges, resembling a "U" shape. It is located at the rear end of the right step frame longitudinal beam 31 and is connected to the upper surface and the inner surface. The mounting surface is perpendicular to the upper surface of the right step frame longitudinal beam 31, and the two flanges are perpendicular to the inner surface of the right step frame longitudinal beam 31. The opening of the "U" shape faces the outside of the right step frame longitudinal beam 31. The tilt pump mounting bracket 351 is used to install the tilt pump. The tilt controller mounting bracket 352 has an "L" shape. The short side of the "L" shape of the tilt controller mounting bracket 352 is connected to the side surface of the tilt pump mounting bracket 351 near the right step frame mounting plate assembly 32. The tilt controller mounting bracket 352 is used to install the tilt controller.

[0035] Both the left step frame assembly 20 and the right step frame assembly 30 are equipped with dedicated front bumper connection structures, which are positioned, supported, and connected to the frame portion of the front bumper 2, respectively. By combining the main reference provided by the front lower protection assembly 10 with the auxiliary reference provided by the front bumper 2, a dual positioning and dual constraint assembly system is formed, which further improves the relative positional accuracy between the step plate, the front bumper 2, and the vehicle body. This reduces the risk of loosening, displacement, abnormal noise, and increased gaps under long-term bumpy and vibrating conditions, thereby improving the overall reliability, safety, and driving experience of the vehicle.

[0036] This invention also provides an assembly method for the above-mentioned heavy truck vehicle step mounting structure, characterized by the following steps: Step S1, positioning and welding the crossbeam reinforcing plate 14 and the front lower protective crossbeam 13; pre-installing the front lower protective mounting plate 11 and the step mounting plate 12 on the crossbeam reinforcing plate 14 respectively, and forming a complete front lower protective assembly 10 by welding, thus completing the modular pre-assembly; Step S2, pre-assembling the left step frame assembly 20 and the right step frame assembly 30 respectively: positioning and welding the respective step frame longitudinal beams, mounting plate groups, front protective connecting plates, and step support plates; simultaneously pre-installing the tilt pump mounting bracket 351 and the tilt controller mounting bracket 352 on the right step frame assembly 30, forming two complete left and right step frame modules.

[0037] Step S3: Connect the pre-installed front lower protection assembly 10 to the frame casting 1 via the front lower protection mounting plate 11, and tighten it with bolts to complete the vehicle installation of the front lower protection assembly and determine the overall installation benchmark.

[0038] Step S4: Position the left step frame assembly 20 and the right step frame assembly 30 respectively with the step mounting plate 12 on the front lower protection assembly 10 through their respective mounting plate groups, and fix them with bolts to achieve integrated assembly of the step frame and the front lower protection assembly.

[0039] Step S5: Confirm that the tilt pump mounting unit 35 is assembled in place at the rear end of the right step frame longitudinal beam 31, check the tightness of each mounting point, the positioning accuracy of each component, the gap and step difference, and finally complete the overall assembly.

[0040] The above assembly methods enable modular pre-assembly, high-precision positioning, and high-efficiency final assembly, significantly improving the operational efficiency of the vehicle assembly line, reducing assembly difficulty, and enhancing the stability of assembly quality.

[0041] The heavy-duty truck step mounting structure provided by this invention effectively solves the industry pain points of traditional heavy-duty truck step structures, such as low assembly precision, insufficient structural strength, redundant parts, and low assembly efficiency, through innovative integrated design, rational structural layout, and precise connection methods. It achieves significant breakthroughs in multiple dimensions, including integration, precision control, structural reliability, lightweighting, assembly efficiency, and functional expandability, resulting in excellent technical effects in many aspects. It comprehensively improves the performance, assembly quality, and market competitiveness of heavy-duty truck step structures. The specific technical effects are summarized as follows: The core technical effect of this invention lies in the high integration of the step structure and the front lower protection structure. It breaks the traditional model of independent design and installation of heavy-duty truck steps and front lower protection. The left step frame assembly 20 and the right step frame assembly 30 are directly integrated into the front lower protection assembly 10. Relying on the existing structure of the front lower protection assembly 10 as the mounting base for the step, there is no need to set up additional independent step brackets, transition brackets, and other parts, which greatly reduces the number and types of parts. In traditional structures, the steps need to be connected to the frame and front bumper through multiple independent brackets, resulting in significant component redundancy. This not only increases material consumption but also raises manufacturing and inventory management costs. In contrast, this invention reduces the use of independent brackets through integrated design, simplifies the overall structure, reduces material consumption and component processing costs, and also reduces the types and quantities of inventory components, thereby lowering the overall costs of production, warehousing, and transportation.

[0042] Furthermore, this invention innovatively integrates a tilt pump mounting unit 35 onto the right step frame assembly 30, directly mounting the tilt pump, tilt controller, and other cab tilt mechanism accessories onto the step frame. This eliminates the need for separate brackets used in traditional designs to mount such accessories, achieving integrated construction of the step structure, front lower protection structure, and tilt pump accessories. This multi-component integrated design not only further simplifies the layout of vehicle accessories and reduces the number of parts, but also improves the utilization rate of the vehicle's front space, making the chassis accessory layout more compact and rational. It avoids layout conflicts caused by excessive space occupied by independent brackets, while also simplifying the assembly process and reducing labor and time costs during assembly.

[0043] This invention, through integrated design, uses the frame casting 1 and the front lower protection assembly 10 as a unified installation benchmark. The front lower protection assembly 10 is precisely connected to the frame casting 1 via the front lower protection mounting plate 11, establishing a stable main benchmark. The left step frame assembly 20 and the right step frame assembly 30 are precisely docked with the front lower protection assembly via the step mounting plate 12, achieving coaxial positioning and synchronous assembly of the step structure and the front lower protection structure. Simultaneously, both the left and right step frame assemblies are equipped with front bumper connecting plates, directly connecting to the front bumper frame, forming a dual positioning system of "frame-front lower protection assembly-step-front bumper," further constraining the relative position of the step and the front bumper, effectively reducing gap fluctuations and step deviations between the step and the front bumper, ensuring uniform gaps and consistent step differences, and significantly improving the overall vehicle appearance refinement and assembly quality. In addition, the precise assembly accuracy avoids the inconvenience of getting in and out of the vehicle caused by the misalignment of the step position, ensuring the comfort and safety of passengers when getting in and out of the vehicle. At the same time, it reduces the friction and collision between the step and the front bumper during vehicle operation, reduces the probability of abnormal noise, and improves the overall driving experience and reliability of the vehicle.

[0044] This invention, through a rational structural design, comprehensively enhances the strength and rigidity of the entire step installation structure, ensuring its adaptability to the long-term and complex operating conditions of heavy trucks. Firstly, the front lower protective crossbeam 13 is made of rectangular straight-seam welded steel pipe. The rectangular closed section possesses extremely high section modulus, bending capacity, and torsional stiffness. As a core load-bearing component, it can effectively withstand frontal impact loads, lateral loads, and the step loads transmitted through the steps, providing a stable load-bearing foundation for the entire structure. Secondly, the crossbeam reinforcing plate 14 adopts a "]"-shaped semi-enclosed structure, covering both ends of the front lower protective crossbeam, effectively improving the local strength and rigidity of the crossbeam ends and preventing deformation or weld cracking caused by stress concentration.

[0045] The front lower protection mounting plate 11 adopts an upward-opening box-shaped closed structure, which is welded together by the side mounting plate 111, the side reinforcing plate 112 and the rear reinforcing plate 113. The box-shaped structure has good torsional and bending resistance, can effectively distribute the load, avoid excessive local stress, and at the same time provide stable support for the connection between the front lower protection assembly 10 and the frame casting 1.

[0046] Both the left and right step frame longitudinal beams are made of rectangular straight-seam welded steel pipes, serving as the main load-bearing components of the step frame. They have advantages such as high strength, light weight, and uniform stress distribution, and can stably transmit step loads. The step frame mounting plate assembly adopts a double "L" shaped structure with symmetrical arrangement, which improves the rigidity and stability of the connection area and avoids deformation caused by unilateral stress. The step support plate adopts an inverted "U" shaped structure and is connected to the step longitudinal beams through multi-face welding to form a stable support structure that can withstand large instantaneous impact loads and long-term cyclic fatigue loads, ensuring the safety of drivers and passengers when getting on and off the vehicle.

[0047] Overall, all components of this invention are made of high-strength materials and have reasonable reinforcement structures. They are welded together to form an integral rigid connection. The force transmission path is clear and uniform, which effectively disperses concentrated loads, reduces the risk of vibration fatigue, and significantly improves the load-bearing capacity, rigidity and fatigue life of the entire step installation structure. This ensures that it can be used stably and reliably for a long time and meets the requirements of high-frequency and high-load use of heavy trucks.

[0048] This invention provides a step mounting structure for heavy-duty trucks, including a front lower protection assembly 10, a left step frame assembly 20, and a right step frame assembly 30. The front lower protection assembly 10 is provided with a front lower protection mounting plate 11 and a step mounting plate 12. The front lower protection assembly 10 is connected to the frame casting 1 through the front lower protection mounting plate 11. The left step frame assembly 20 and the right step frame assembly 30 are connected to the step mounting plate 12. The left step frame assembly 20 and the right step frame assembly 30 are integrated on the front lower protection assembly 10. By utilizing the existing structure and high strength of the front lower protection assembly 10, the lightweighting of the step frame assembly is achieved while improving the assembly accuracy of the step and the front bumper. The front bumper connection structure inside the step frame assembly is connected to the front bumper frame, further improving the assembly accuracy of the step plate and the front bumper 2.

[0049] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A step mounting structure for heavy-duty trucks, characterized in that, It includes a front lower protection assembly (10), a left step frame assembly (20) and a right step frame assembly (30). The front lower protection assembly (10) is provided with a front lower protection mounting plate (11) and a step mounting plate (12). The front lower protection assembly (10) is connected to the frame casting (1) through the front lower protection mounting plate (11). The left step frame assembly (20) and the right step frame assembly (30) are connected to the step mounting plate (12).

2. The heavy-duty truck step mounting structure according to claim 1, characterized in that, The front lower protection assembly (10) also includes a front lower protection crossbeam (13) and a crossbeam reinforcing plate (14). The crossbeam reinforcing plate (14) is respectively disposed at both ends of the front lower protection crossbeam (13). The front lower protection mounting plate (11) and the step mounting plate (12) are disposed on the crossbeam reinforcing plate (14). The front lower protection mounting plate (11) is located inside the step mounting plate (12).

3. The heavy-duty truck step mounting structure according to claim 2, characterized in that, The front lower protective mounting plate (11) includes a side mounting plate (111), a side reinforcing plate (112), and a rear reinforcing plate (113). One side of the rear reinforcing plate (113) is connected to the side mounting plate (111), and the other side of the rear reinforcing plate (113) is connected to the side reinforcing plate (112), and is located between the side mounting plate (111) and the side reinforcing plate (112).

4. The heavy-duty truck step mounting structure according to claim 3, characterized in that, The step mounting plate (12) includes a step frame mounting plate (121) and a first flange (122) and a second flange (123) disposed on the step frame mounting plate (121). The step frame mounting plate (121) is provided with step frame mounting points (124). The first flange (122) is located on the upper side, left side and right side of the step frame mounting plate (121). The second flange (123) is located on the lower side of the step frame mounting plate (121). The length of the second flange (123) is longer than the length of the first flange (122).

5. The heavy-duty truck step mounting structure according to claim 4, characterized in that, The left step frame assembly (20) includes a left step frame longitudinal beam (21), a left step frame mounting plate assembly (22), a left step frame front support connecting plate (23), and a left step foot support plate (24). The left step frame longitudinal beam (21) is connected to the left step frame mounting plate assembly (22), and the left step frame mounting plate assembly (22) is connected to the step frame mounting plate (121). The left step frame front support connecting plate (23) is disposed on the left step frame longitudinal beam (21), and the left step foot support plate (24) is disposed on the left step frame longitudinal beam (21).

6. The heavy-duty truck step mounting structure according to claim 5, characterized in that, The left step frame mounting plate assembly (22) includes a first frame mounting plate (221) and a second frame mounting plate (222). Both the first frame mounting plate (221) and the second frame mounting plate (222) are "L" shaped and are respectively arranged on both sides of the left step frame longitudinal beam (21).

7. The heavy-duty truck step mounting structure according to claim 4, characterized in that, The right step frame assembly (30) includes a right step frame longitudinal beam (31), a right step frame mounting plate assembly (32), a right step frame front support connecting plate (33), and a right step foot support plate (34). The right step frame longitudinal beam (31) is connected to the right step frame mounting plate assembly (32), and the right step frame mounting plate assembly (32) is connected to the step frame mounting plate (121). The right step frame front support connecting plate (33) is disposed on the right step frame longitudinal beam (31), and the right step foot support plate (34) is disposed on the right step frame longitudinal beam (31).

8. The heavy-duty truck step mounting structure according to claim 7, characterized in that, The right step frame mounting plate assembly (32) includes a third frame mounting plate (321) and a fourth frame mounting plate (322). The third frame mounting plate (321) and the fourth frame mounting plate (322) are both "L" shaped and are respectively arranged on both sides of the right step frame longitudinal beam (31).

9. The heavy-duty truck step mounting structure according to claim 7, characterized in that, The right step frame assembly (30) also includes a tilt pump mounting unit (35), which includes a tilt pump mounting bracket (351) and a tilt controller mounting bracket (352) connected to the tilt pump mounting bracket (351). The tilt pump mounting bracket (351) is mounted on the right step frame longitudinal beam (31) and is located at the rear end of the right step frame longitudinal beam (31).

10. An assembly method for a heavy-duty truck step mounting structure according to claims 1 to 9, characterized in that, Includes the following steps: Step S1: Assemble the crossbeam reinforcing plate (14) and the front lower protective crossbeam (13), and pre-install the front lower protective mounting plate (11) and the step mounting plate (12) on the crossbeam reinforcing plate (14) to form the front lower protective assembly (10); Step S2: Pre-install the left step frame assembly (20) and the right step frame assembly (30) with their respective frame longitudinal beams, mounting plate groups, front bumper connecting plates and pedal support plates; Step S3: Fix the front lower protective assembly (10) to the frame casting (1) through the front lower protective mounting plate (11); Step S4: Fix the left step frame assembly (20) and the right step frame assembly (30) to the corresponding step mounting plate (12) on the front lower protective assembly through their respective mounting plate groups; Step S5: Install the tilt pump mounting bracket (351) and the tilt controller mounting bracket (352) at the rear end of the right step frame longitudinal beam (31) to complete the overall assembly.

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