A commercial vehicle body-in-white

Abstract

The application belongs to the technical field of vehicle manufacturing, and discloses a commercial vehicle body-in-white. The commercial vehicle body-in-white comprises a roof, a left side wall and a right side wall, the left side wall and the right side wall are installed on the lower side of the roof, the roof is symmetrically provided with two roof panels, the two roof panels are bent towards the inside of the vehicle to form first flanges, the left side wall comprises a left outer panel, the upper side of the left outer panel is recessed towards the inside of the vehicle to form a first mounting table, the first flange is placed on the first mounting table, the right side wall comprises a right outer panel, the upper side of the right outer panel is recessed towards the inside of the vehicle to form a second mounting table, and the first flange is placed on the second mounting table. The commercial vehicle body-in-white solves the problem that shielding parts need to be added to shield the welds in the machining process of the commercial vehicle body-in-white.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle manufacturing, in particular to a commercial vehicle body-in-white. BACKGROUND

[0002] As an important link in the modern industrial system, the development level of commercial vehicle body manufacturing process is directly related to the quality and market competitiveness of the whole vehicle. In the increasingly competitive market environment, commercial vehicle manufacturers not only need to ensure the structural safety and functional reliability of the product, but also need to achieve an effective balance between improving the appearance quality and optimizing the production cost. In the manufacturing process commonly used in the industry at present, the body-in-white as the basic carrier of the vehicle framework has a decisive influence on the subsequent assembly process and the final product performance.

[0003] The traditional commercial vehicle body-in-white structure is usually composed of six core components, including a roof assembly, a left side wall assembly, a right side wall assembly, a front wall assembly, a rear wall assembly and a floor assembly. Each component is connected by welding process. Although this classic body construction method has been followed for many years, it gradually exposes many technical limitations in the actual production process. In particular, in terms of welding joint processing, the weld formed by the overlap of each component is directly exposed to the outer surface of the body, which not only destroys the overall coordination of the body appearance, but also adversely affects the subsequent painting process and the final product image. To make up for this process defect, the current common practice is to additionally add a shielding part during the exterior design stage to hide the weld marks by covering the additional decorative parts, but this passive repair scheme is essentially a compromise for the process defect. Although this shielding part installation process meets the basic demand of appearance beautification to some extent, it brings multiple negative effects from the perspective of life cycle cost. First, the mold development and production of the shielding part require additional R&D funds and equipment resources, which directly increases the material cost of a single vehicle. Second, the assembly process of the shielding part increases the setting of the production line stations, which leads to the complication of the process flow and indirectly affects the overall production efficiency. More importantly, the cumulative effect of the additional parts may make it difficult to achieve the lightweight design goal of the whole vehicle, which is potentially in conflict with the current industry's development trend of energy saving and emission reduction. This band-aid solution reflects the shortcomings of the traditional process in terms of systematic design thinking and integrated innovation.

[0004] Another key factor restricting production efficiency is the complexity of the existing connection process. To achieve reliable connection of each vehicle body component, the current process generally uses an intermediate connecting plate as a transition structural member to connect different assemblies. This technical solution requires precise positioning and multiple welding of each connecting plate, which not only significantly increases the number of welding operations, but also requires higher precision control of the production equipment. In a large-scale production scenario, each additional welding process means a corresponding extension of the production cycle, as well as multiple cost effects such as energy consumption, equipment wear, quality risk, etc. In the process of connecting the roof with other components, the longitudinal beam on the roof is connected with the cross beam on the corresponding component, but only through a small area of the longitudinal beam cross section to connect with the cross beam, which also causes the welding gun to be unable to extend into the area, the area available for welding is too small, and the area after welding cannot meet the strength requirements of the design. Therefore, in order to facilitate processing and meet the design requirements, a welding connecting plate needs to be introduced between the roof and other components to enable the structural member.

[0005] From the perspective of industrial upgrading, these technical bottlenecks in traditional processes have seriously restricted the sustainable development ability of enterprises. With the continuous improvement of consumers' requirements for vehicle appearance quality and the fierce market competition, it is difficult to meet market demand by relying solely on post-remedial measures. The exposure of the vehicle body weld not only affects the visual expression of the product, but also may be interpreted by the end user as a quality defect of the manufacturing process, which poses a potential threat to brand image building. At the same time, the redundancy trend of the welding process leads to high production costs, directly weakening the enterprise's initiative in price competition.

[0006] Today, with the deep-rooted concepts of intelligent manufacturing and lean production, the traditional process model has been unable to meet the needs of modern production. The welding operation on different components not only wastes time, but also may affect the assembly accuracy of the vehicle body due to the cumulative error effect. This systematic defect often needs to be corrected repeatedly in the later stage, forming a vicious cycle. In addition, the excessive use of connecting transition parts increases the redundancy of the vehicle body structure, which is contrary to the industry trend of lightweight design. This technical lag in the process has become an important obstacle to the high-quality development of commercial vehicle manufacturing enterprises. SUMMARY

[0007] The purpose of the present application is to provide a commercial vehicle body-in-white, which solves the problem of the need to increase shielding parts to shield welds in the processing of the commercial vehicle body-in-white in the prior art.

[0008] To achieve the above object, the present application adopts the following technical scheme: the present application provides a commercial vehicle body-in-white, comprising a roof, a left side wall and a right side wall, the left side wall and the right side wall are installed on the lower side of the roof, the roof is symmetrically provided with a top plate on both sides, the top plate on both sides is bent to form a first flange on the side of the vehicle interior, the left side wall comprises a left outer plate, the upper side of the left outer plate is recessed to form a first mounting table on the side of the vehicle interior, the first flange is placed on the first mounting table, the right side wall comprises a right outer plate, the upper side of the right outer plate is recessed to form a second mounting table on the side of the vehicle interior, and the first flange is placed on the second mounting table.

[0009] Preferably, the left outer plate extends a first fixing plate on the upper side of the first mounting table, the first fixing plate is installed with a left outer beam on the side of the vehicle interior, the left outer beam is installed with a left inner beam on the side close to the vehicle interior, and the left outer beam and the left inner beam are both raised to form a cavity.

[0010] Preferably, the right outer plate extends a second fixing plate on the upper side of the second mounting table, the second fixing plate is installed with a right outer beam on the side of the vehicle interior, the right outer beam is installed with a right inner beam on the side close to the vehicle interior, and the right outer beam and the right inner beam are both raised to form a cavity.

[0011] Preferably, the commercial vehicle body-in-white further comprises a rear wall, the rear wall comprises a rear outer plate, a rear inner cross beam and a rear outer cross beam, the upper side of the rear outer plate is bent to form a second flange on the side of the vehicle exterior, the second flange is installed with a rear outer cross beam, the lower end of the rear outer cross beam is connected with the rear outer plate, and the rear outer cross beam is further installed with a rear inner cross beam on the side of the vehicle interior.

[0012] Preferably, the rear inner cross beam is bent to form a third flange on the end close to the vehicle interior, the rear side of the roof is installed with a top cross beam, the cross section of the top cross beam is in the shape of a U, one side of the top cross beam is connected with the third flange, and the other side is connected with the second flange, and the top cross beam, the rear inner cross beam and the rear outer cross beam form a cavity.

[0013] Preferably, the commercial vehicle body-in-white further comprises a first connecting plate, the upper side of the first connecting plate is connected with a first connecting piece, the first connecting piece is connected with the top cross beam, the main body of the first connecting plate is in the shape of L, one side of the first connecting plate is connected with the rear inner cross beam, and the other side is connected with the left inner beam.

[0014] Preferably, the commercial vehicle body-in-white further comprises a second connecting plate, the second connecting plate is installed on the side close to the vehicle exterior of the first connecting plate, one side of the second connecting plate is connected with the left side wall, and the other side is connected with the rear wall.

[0015] As preferably, the commercial vehicle body-in-white further comprises a third connecting plate, a second connecting sheet is connected to the upper side of the third connecting plate, the second connecting sheet is connected with the top cross beam, the main body of the third connecting plate is L-shaped, one side of the third connecting plate is connected with the rear inner cross beam, and the other side is connected with the right inner beam.

[0016] As preferably, the commercial vehicle body-in-white further comprises a fourth connecting plate, the fourth connecting plate is installed on the side of the third connecting plate close to the outside of the vehicle, one side of the fourth connecting plate is connected with the right side wall, and the other side is connected with the rear wall.

[0017] As preferably, the commercial vehicle body-in-white further comprises a front wall and a floor, the floor is welded around the front wall, the left side wall, the right side wall and the rear wall respectively, the lower side of the top cover is welded with the front wall, the left side wall, the right side wall and the rear wall respectively, the upper side of the top cover is provided with a middle plate, along the driving direction of the vehicle, the front plate and the rear plate are installed on both sides of the middle plate respectively, the front plate is connected with the front wall, the top plate is installed on both sides of the middle plate, the longitudinal beam is welded on the rear plate, and the lower end of the longitudinal beam is connected with the top cross beam.

[0018] Beneficial effects: the left outer plate and the right outer plate are recessed into the commercial vehicle body at the same time to form the first mounting table and the second mounting table, and the top plate on the top cover is also bent inward, when the top plate and the left side wall and the right side wall are welded, welding is required from the inside of the vehicle, the welding seam is clamped between the first flange and the first mounting table, and the welding seam on the other side is also clamped between the second flange and the second mounting table, the welding seam is located in the vehicle, so that the vehicle is more beautiful after welding, without the need to install a decorative plate, and the production cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the main body diagram of the commercial vehicle body-in-white of the present application;

[0020] Figure 2 is the main body diagram of the top cover of the present application;

[0021] Figure 3 is the exploded view of the left side wall of the present application;

[0022] Figure 4 is the exploded view of the right side wall of the present application;

[0023] Figure 5 is the exploded view of the rear wall of the present application;

[0024] Figure 6 is the sectional installation diagram of the left inner beam of the present application;

[0025] Figure 7 is the sectional installation diagram of the right inner beam of the present application;

[0026] Figure 8is a schematic view of the top crossbeam and rear wall connection of the present application;

[0027] Figure 9 is a schematic view of the left side wall, rear wall and right side wall body connection of the present application;

[0028] Figure 10 is a first connecting plate installation view of the present application;

[0029] Figure 11 is a third connecting plate installation view of the present application;

[0030] Figure 12 is a commercial vehicle body-in-white explosion view of the present application.

[0031] In the figure: 1, roof; 11, top plate; 111, first flange; 12, top crossbeam; 13, middle plate; 14, front plate; 15, rear plate; 16, longitudinal beam; 2, left side wall; 21, left outer plate; 211, first mounting table; 212, second connecting plate; 22, first fixed plate; 23, left outer beam; 24, left inner beam; 3, right side wall; 31, right outer plate; 311, second mounting table; 312, fourth connecting plate; 32, second fixed plate; 33, right outer beam; 34, right inner beam; 4, floor; 5, rear wall; 51, rear outer plate; 511, second flange; 52, rear inner crossbeam; 521, third flange; 53, rear outer crossbeam; 6, front wall; 7, first connecting plate; 71, first connecting piece; 8, third connecting plate; 81, second connecting piece. DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with the accompanying drawings and examples. It can be understood that the specific examples described herein are only used to explain the present application, and not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, not all the structures.

[0033] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] In the present application, unless otherwise explicitly specified and limited, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "over" of a first feature to a second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. "Under", "below" and "underneath" of a first feature to a second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0035] In the description of the present embodiment, the terms "upper", "lower", "right", "left", and the like, orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only used to distinguish in description, and have no special meaning.

[0036] Under the prior art, commercial vehicle processing needs to be processed around the body-in-white, and the body-in-white of the commercial vehicle includes several parts, including the roof, the left side wall, the right side wall, the front wall, the rear wall and the floor, each part is connected together by welding. In the process of processing under the prior art, the contact position of each position of the roof, the left side wall, the right side wall, the front wall and the floor will form a weld, and the weld is located outside the vehicle. In order to make the body beautiful, a shielding member needs to be installed on the outside of the body-in-white to shield the weld, so as to avoid the weld from being exposed outside, making the finally processed body more beautiful, but the shielding member will increase the manufacturing cost of the commercial vehicle. At the same time, in the process of processing the existing commercial vehicle, the roof, the left side wall, the right side wall, the front wall and the floor need to be connected by an additional connecting plate. In the connecting process of the roof and the rear wall, the longitudinal beam on the roof needs to be transitionally welded with the cross beam on the rear wall through the connecting plate, so as to make the welding area larger and maintain the strength after welding. However, this will increase the welding process, resulting in a longer welding process and increasing the welding cost.

[0037] In order to solve the above problems, as Figures 1 to 12As shown, the present application provides a commercial vehicle body-in-white, which comprises a roof 1, a left side wall 2 and a right side wall 3, the left side wall 2 and the right side wall 3 are installed below the roof 1, the roof 1 is symmetrically provided with a top plate 11 on both sides, the first flange 111 is formed by bending the top plate 11 towards the inside of the vehicle, the left side wall 2 comprises a left outer plate 21, the upper side of the left outer plate 21 is recessed towards the inside of the vehicle to form a first mounting table 211, the first flange 111 is placed on the first mounting table 211, the right side wall 3 comprises a right outer plate 31, the upper side of the right outer plate 31 is recessed towards the inside of the vehicle to form a second mounting table 311, and the first flange 111 is placed on the second mounting table 311.

[0038] By opening the first mounting table 211 on the left outer plate 21, opening the second mounting table 311 on the right outer plate 31, and placing the first flange 111 on both sides of the top plate 11 on the first mounting table 211 and the second mounting table 311 for welding, since the first flange 111 is bent towards the inside of the vehicle, the position of the weld can be moved to the inside of the vehicle, the weld exists in the gap between the first flange 111 and the first mounting table 211, and the gap between the first flange 111 and the second mounting table 311, so that the weld is not directly exposed to the outside of the vehicle, saving the decorative plate and reducing the production cost of the vehicle. During the welding process, the position of the welding gun is inside the vehicle, so that the final formed weld is located on the inside of the vehicle, avoiding the exposure of the weld to the outside.

[0039] The left outer plate 21 extends a first fixing plate 22 on the upper side of the first mounting table 211, the first fixing plate 22 is installed with a left outer beam 23 on the inside of the vehicle, the left outer beam 23 is installed with a left inner beam 24 on the side close to the inside of the vehicle, and the left outer beam 23 and the left inner beam 24 are both raised to form a cavity.

[0040] The space where the first fixing plate 22 is located is the inside of the vehicle, and the left outer beam 23 and the left inner beam 24 are sequentially attached to the first fixing plate 22, and the left outer beam 23 and the left inner beam 24 are welded to the first fixing plate 22 inside the vehicle, so that the weld can be left inside the vehicle, reducing the number of covering plates used, and at the same time, the left outer beam 23 and the left inner beam 24 are welded inside the vehicle, so that the weld can be left inside the vehicle. The left outer beam 23 and the left inner beam 24 are both raised to form a cavity and are fixed by welding, which can provide a certain structural strength for the commercial vehicle body-in-white.

[0041] The right outer plate 31 extends a second fixing plate 32 on the upper side of the second mounting table 311, the second fixing plate 32 is installed with a right outer beam 33 on the inside of the vehicle, the right outer beam 33 is installed with a right inner beam 34 on the side close to the inside of the vehicle, and the right outer beam 33 and the right inner beam 34 are both raised to form a cavity.

[0042] The space where the second fixed plate 32 is located is in the vehicle, and the right outer beam 33 and the right inner beam 34 are sequentially attached to the second fixed plate 32 in the vehicle, so that the welding seam can be left in the vehicle, the number of cover plates used is reduced, and the right outer beam 33 and the right inner beam 34 are welded in the vehicle in the form of welding, so that the welding seam can be left in the vehicle, the right outer beam 33 and the right inner beam 34 are both raised to form a cavity and are fixed by welding, and a certain structural strength can be provided for the commercial vehicle body in white.

[0043] The commercial vehicle body in white further comprises a rear wall 5, and the rear wall 5 comprises a rear outer plate 51, a rear inner cross beam 52 and a rear outer cross beam 53.

[0044] The rear inner cross beam 52 is bent to form a third flange 521 at a side close to the vehicle, the roof 1 is provided with a top cross beam 12 at the rear side, the top cross beam 12 has a U-shaped cross section, one side of the top cross beam 12 is connected to the third flange 521, and the other side of the top cross beam 12 is connected to the second flange 511, and the top cross beam 12, the rear inner cross beam 52 and the rear outer cross beam 53 form a cavity.

[0045] The top cross beam 12 is connected to the rear wall 5, the left side wall 2 and the right side wall 3, the welding connecting plate between the original top cross beam 12 and the rear wall 5 is cancelled, the U-shaped top cross beam 12 is installed at the rear side of the roof 1, the two sides of the top cross beam 12 in the width direction are connected to the first connecting piece 71 and the second connecting piece 81 respectively, the contact area between the top cross beam 12 and the rear wall 5 is increased, the contact strength between the rear wall 5 and the top cross beam 12 is increased, the top cross beam 12 is connected to the roof 1 in advance, the original welding connecting plate is replaced, and the production cost of the body in white is reduced.

[0046] The commercial vehicle body in white further comprises a first connecting plate 7, and the first connecting plate 7 is connected to the first connecting piece 71 at the upper side, the first connecting piece 71 is connected to the top cross beam 12, the main body of the first connecting plate 7 is L-shaped, one side of the first connecting plate 7 is connected to the rear inner cross beam 52, and the other side of the first connecting plate 7 is connected to the left inner beam 24.

[0047] The first connecting plate 7 of the present application can simultaneously connect the rear wall 5, the left side wall 2 and the roof 1, fix the above three, and improve the overall structural strength of the commercial vehicle body in white.

[0048] The commercial vehicle body-in-white further comprises a second connecting plate 212, which is installed on the side of the first connecting plate 7 close to the outside of the vehicle, and is connected with the left side wall 2 on one side and the rear wall 5 on the other side.

[0049] The commercial vehicle body-in-white further comprises a third connecting plate 8, which is connected with a second connecting piece 81 on the upper side, and the second connecting piece 81 is connected with the top cross beam 12.

[0050] The third connecting plate 8 of the present application can simultaneously connect the rear wall 5, the right side wall 3 and the top cover 1, and fix the above three, thereby improving the overall structural strength of the commercial vehicle body-in-white.

[0051] The commercial vehicle body-in-white further comprises a fourth connecting plate 312, which is installed on the side of the third connecting plate 8 close to the outside of the vehicle, and is connected with the right side wall 3 on one side and the rear wall 5 on the other side.

[0052] The commercial vehicle body-in-white further comprises a front wall 6 and a floor 4, which are respectively welded with the front wall 6, the left side wall 2, the right side wall 3 and the rear wall 5 around, and finally splice the commercial vehicle body-in-white in a rectangular state.

[0053] The top cover 1 is welded with the front wall 6, the left side wall 2, the right side wall 3 and the rear wall 5 on the lower side, and is provided with a middle plate 13 on the upper side.

[0054] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the scope of the present application. It is not necessary or possible to enumerate all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A commercial vehicle body-in-white, characterized in that, The device includes a top cover (1), a left side panel (2), and a right side panel (3). The left side panel (2) and the right side panel (3) are installed on the underside of the top cover (1). The top cover (1) has a top plate (11) installed on both sides symmetrically. The top plates (11) on both sides are bent towards the inside of the vehicle to form a first flange (111). The left side panel (2) includes a left outer plate (21). The upper side of the left outer plate (21) is recessed towards the inside of the vehicle to form a first mounting platform (211). The first flange (111) is placed on the first mounting platform (211). The right side panel (3) includes a right outer plate (31). The upper side of the right outer plate (31) is recessed towards the inside of the vehicle to form a second mounting platform (311). The first flange (111) is placed on the second mounting platform (311). The commercial vehicle body-in-white also includes a rear panel (5), which includes a rear outer panel (51), a rear inner crossbeam (52), and a rear outer crossbeam (53). The upper side of the rear outer panel (51) is bent outward to form a second flange (511). The rear outer crossbeam (53) is installed on the second flange (511). The lower end of the rear outer crossbeam (53) is connected to the rear outer panel (51). The rear outer crossbeam (53) also has a rear inner crossbeam (52) installed on the inner side of the vehicle. The rear inner crossbeam (52) is bent at one end near the vehicle interior to form a third flange (521). A top crossbeam (12) is installed on the rear side of the roof (1). The cross section of the top crossbeam (12) is shaped like a "Z". One side of the top crossbeam (12) is connected to the third flange (521), and the other side is connected to the second flange (511). The top crossbeam (12), the rear inner crossbeam (52), and the rear outer crossbeam (53) form a cavity.

2. The commercial vehicle body-in-white according to claim 1, characterized in that, The left outer plate (21) extends from the upper side of the first mounting platform (211) by the first fixing plate (22). The first fixing plate (22) has a left outer beam (23) installed on the inside side of the vehicle. The left outer beam (23) has a left inner beam (24) installed on the side closer to the inside of the vehicle. The left outer beam (23) and the left inner beam (24) together form a cavity.

3. The commercial vehicle body-in-white according to claim 2, characterized in that, The right outer plate (31) extends the second fixing plate (32) along the upper side of the second mounting platform (311). The second fixing plate (32) has a right outer beam (33) installed on the inner side of the vehicle. The right outer beam (33) has a right inner beam (34) installed on the inner side of the vehicle. The right outer beam (33) and the right inner beam (34) together form a cavity.

4. The commercial vehicle body-in-white according to claim 3, characterized in that, The commercial vehicle body also includes a first connecting plate (7), on which a first connecting piece (71) is connected. The first connecting piece (71) is connected to the top crossbeam (12). The main body of the first connecting plate (7) is L-shaped. One side of the first connecting plate (7) is connected to the rear inner crossbeam (52), and the other side is connected to the left inner beam (24).

5. The commercial vehicle body-in-white according to claim 4, characterized in that, The commercial vehicle body also includes a second connecting plate (212), which is installed on the side of the first connecting plate (7) near the outside of the vehicle. One side of the second connecting plate (212) is connected to the left side panel (2), and the other side is connected to the rear panel (5).

6. The commercial vehicle body-in-white according to claim 5, characterized in that, The commercial vehicle body also includes a third connecting plate (8), on which a second connecting piece (81) is connected. The second connecting piece (81) is connected to the top crossbeam (12). The main body of the third connecting plate (8) is L-shaped. One side of the third connecting plate (8) is connected to the rear inner crossbeam (52), and the other side is connected to the right inner beam (34).

7. The commercial vehicle body-in-white according to claim 6, characterized in that, The commercial vehicle body also includes a fourth connecting plate (312), which is installed on the side of the third connecting plate (8) near the outside of the vehicle. One side of the fourth connecting plate (312) is connected to the right side panel (3), and the other side is connected to the rear panel (5).

8. The commercial vehicle body-in-white according to claim 7, characterized in that, The commercial vehicle body-in-white also includes a front bulkhead (6) and a floor (4). The floor (4) is welded to the front bulkhead (6), the left side bulkhead (2), the right side bulkhead (3), and the rear bulkhead (5) on all four sides. The front bulkhead (6), the left side bulkhead (2), the right side bulkhead (3), and the rear bulkhead (5) are welded to the lower side of the top cover (1). A middle plate (13) is provided on the upper side of the top cover (1). Along the vehicle driving direction, a front plate (14) and a rear plate (15) are installed on both sides of the middle plate (13). The front plate (14) is connected to the front bulkhead (6). The top plate (11) is installed on both sides of the middle plate (13). A longitudinal beam (16) is welded on the rear plate (15). The lower end of the longitudinal beam (16) is connected to the top crossbeam (12).

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