A front subframe assembly for automobiles and a method for assembling the front subframe assembly.

Abstract

This invention relates to the field of subframes, specifically to a front subframe assembly and its assembly method, comprising a longitudinal beam assembly and a crossbeam assembly. The longitudinal beam assembly includes a longitudinal beam body, which in turn includes two relatively distributed individual longitudinal beam assemblies. The two individual longitudinal beam assemblies are connected by a crossbeam assembly. Each individual longitudinal beam assembly includes a longitudinal beam body. The crossbeam assembly includes a front crossbeam, a middle crossbeam, and a rear crossbeam. The longitudinal beam bodies and crossbeam assemblies of the two individual longitudinal beam assemblies form a U-shaped structure. This invention discloses a front subframe assembly for automobiles. By changing the structure of the traditional crossbeam assembly, this invention makes the main structure of the subframe assembly U-shaped, greatly increasing the overall structural strength of the front subframe assembly.

Description

Technical Field

[0001] This invention relates to the field of subframes, specifically to a front subframe assembly for automobiles and a method for assembling the front subframe assembly. Background Technology

[0002] With the rapid development of the new energy vehicle market, the performance requirements for the whole vehicle are becoming higher and higher, the safety performance is more stringent, the reliability is longer and the mileage is longer, and the requirements for energy saving and consumption reduction are more stringent. In order to meet these requirements, the subframe plays a crucial role in the whole vehicle.

[0003] The subframe is an important component of a vehicle, forming a crucial part of the overall chassis.

[0004] The subframe has two main functions: one is to reduce the noise and vibration transmitted from the road surface and powertrain to the whole vehicle, thereby improving the passenger's riding experience; the other is to serve as a carrier for chassis components, allowing chassis parts to be first installed on the subframe to form an assembly, and then the whole assembly to be installed on the vehicle body, which facilitates the assembly and load-bearing of the whole vehicle.

[0005] The subframe needs to have a stronger load-bearing capacity to better meet the installation requirements of the suspension system, steering system, motor, and other components.

[0006] Currently, the front subframe structures commonly used in the market are basically of two types: frame type and butterfly type, each with certain limitations. In view of the development trend of electric vehicles, the wheelbase is getting longer and longer, increasing the overall vehicle space, ensuring the overall vehicle collision safety, and high comfort performance. High-end vehicles are basically equipped with double wishbone suspension systems, and at the same time, air spring configurations are used to make the whole vehicle lightweight, increase the range, and achieve commonality within the same platform to maximize costs.

[0007] The motor is mounted on the subframe via a suspension system, making assembly and replacement convenient and performance tuning easy.

[0008] A front subframe is now required in order to meet at least one of the above requirements for arrangement, structure, or function. Summary of the Invention

[0009] The purpose of this invention is to provide a front subframe assembly structure with high overall structural strength.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A front subframe assembly for an automobile includes a longitudinal beam assembly and a crossbeam assembly; the longitudinal beam assembly includes a longitudinal beam body, and the longitudinal beam body includes two relatively distributed individual longitudinal beam assemblies; the two individual longitudinal beam assemblies are connected by a crossbeam assembly.

[0012] The single longitudinal beam assembly includes a longitudinal beam body; the longitudinal beam body includes a front longitudinal beam and a rear longitudinal beam; the front longitudinal beam is connected to the rear longitudinal beam.

[0013] The crossbeam assembly includes a front crossbeam, a middle crossbeam, and a rear crossbeam;

[0014] The front crossbeam is connected to two front longitudinal beams at both ends; the rear crossbeam is connected to two rear longitudinal beams at both ends.

[0015] The longitudinal beams and crossbeams of the two individual longitudinal beam assemblies form a L-shaped structure.

[0016] The longitudinal beam assembly also includes a mounting arm mechanism disposed on the longitudinal beam body, the mounting arm mechanism including a mounting arm disposed on the longitudinal beam body; the mounting arm is arc-shaped.

[0017] Each of the mounting arms is provided with a T-shaped sleeve; the T-shaped sleeve is provided with a toothed roller on the side near the vehicle body.

[0018] The front crossbeam, middle crossbeam, and rear crossbeam are spaced apart; the front crossbeam is connected to two oppositely distributed front longitudinal beams; the middle crossbeam and the rear crossbeam are respectively connected to the rear longitudinal beams at both ends.

[0019] The rear longitudinal beam is equipped with multiple motor connecting shafts.

[0020] The front longitudinal beam is equipped with a steering gear connecting shaft.

[0021] The front subframe assembly also includes a swing arm connecting mechanism, which includes a lower swing arm fixing bracket connected to the front longitudinal beam; the vertical cross-section of the lower swing arm fixing bracket is Ω-shaped.

[0022] A reinforcing plate is provided at the connection between the front longitudinal beam and the rear longitudinal beam.

[0023] Each of the longitudinal beams is provided with a front lower crossbeam mounting seat at its end, and the front lower crossbeam mounting seat is connected to the longitudinal beam by corner welding.

[0024] A method for assembling a front subframe assembly of an automobile, the assembly method comprising the following steps:

[0025] Step 1: First, assemble the two individual longitudinal beam assemblies and the crossbeam assembly separately;

[0026] Step 2: After completing Step 1, assemble the two individual longitudinal beam assemblies with the transverse beam assembly;

[0027] Step 3: After completing Step 2, a front subframe assembly is assembled. If you need to assemble the front subframe assembly again, repeat Steps 1-2.

[0028] The advantages of the present invention are as follows:

[0029] The present invention discloses an automotive front subframe assembly. By changing the structure of the traditional crossbeam assembly, the main structure of the subframe assembly is in the shape of a "Lv" character, greatly increasing the overall structural strength of the front subframe assembly. In addition, the front subframe assembly of the present invention adopts a modular design, which not only meets the service performance of the subframe but also effectively increases the applicability and universality of the subframe and reduces the development cost of the subframe. Brief Description of the Drawings

[0030] The following briefly describes the content expressed in each drawing of the present invention specification and the marks in the drawings:

[0031] Figure 1 is the top view of the present invention.

[0032] Figure 2 is the left front view of the present invention.

[0033] Figure 3 is the left rear view of the present invention.

[0034] Figure 4 is the composition diagram of the components during the assembly of the present invention.

[0035] Figure 5 is the cross-sectional view of the longitudinal beam body in the present invention.

[0036] Figure 6 is the cross-sectional view of the front crossbeam in the present invention.

[0037] Figure 7 is the cross-sectional view of the middle crossbeam in the present invention.

[0038] Figure 8 is the cross-sectional view of the rear crossbeam in the present invention.

[0039] The marks in the above figures are all:

[0040] 1. Front crossbeam, 2. Right mounting seat of the front bumper lower crossbeam, 3. Left front mounting bent arm of the subframe, 4. Lower arm fixing bracket, 5. Right front longitudinal beam section, 6. Right middle mounting bent arm of the subframe, 7. Right rear lower arm fixing bracket, 8. Right rear longitudinal beam section, 9. Rear crossbeam, 10. Left rear longitudinal beam section, 11. Left rear lower arm fixing bracket, 12. Left middle mounting bent arm, 13. Left front longitudinal beam section, 14. Left front lower arm fixing bracket, 15. Left front mounting bent arm, \16. Left front bumper lower mold beam seat, 17. Middle crossbeam, 18. Reinforcement plate. Detailed Description of the Preferred Embodiment

[0041] The following further details the specific implementation manners of the present invention by describing the preferred embodiments in conjunction with the drawings.

[0042] An automobile front subframe assembly, a longitudinal beam assembly and a crossbeam assembly; the longitudinal beam assembly includes a longitudinal beam main body 1-1, and the longitudinal beam main body 1-1 includes two relatively distributed single longitudinal beam assemblies; the two single longitudinal beam assemblies are connected by the crossbeam assembly; the crossbeam assembly includes a front crossbeam 1, a middle crossbeam 17 and a rear crossbeam 9; the present invention discloses an automobile front subframe assembly. By changing the structure of the traditional crossbeam assembly, the main structure of the subframe assembly is in the shape of a "Lü" character, greatly increasing the overall structural strength of the front subframe assembly; in addition, the front subframe assembly of the present invention adopts a modular design, which not only meets the use performance of the subframe, but also effectively increases the applicability and universality of the subframe, and reduces the development cost of the subframe.

[0043] Specifically, the longitudinal beam assembly disclosed in the present invention includes a longitudinal beam main body 1-1, and the longitudinal beam main body 1-1 is the main structure of the subframe and plays a main supporting role; in addition, in the present invention, the longitudinal beam main body 1-1 includes two relatively distributed single longitudinal beam assemblies; the single longitudinal beam assembly includes a longitudinal beam body 5-1; the longitudinal beam body 5-1 includes a front longitudinal beam 5-11 and a rear longitudinal beam 5-12; the front longitudinal beam 5-11 is connected to the rear longitudinal beam 5-12; in actual arrangement, it is required that the strength of the front longitudinal beam 5-11 is less than that of the rear longitudinal beam 5-12. Such a setting is equivalent to that in subsequent use, the front longitudinal beam 5-11 acts as a collapse section and the rear longitudinal beam 5-12 acts as a strengthening member, ensuring the overall structural strength of the subframe.

[0044] In actual arrangement, in the present invention, the crossbeam assembly includes a front crossbeam 1, a middle crossbeam 17 and a rear crossbeam 9; both ends of the front crossbeam 1 are respectively connected to two front longitudinal beams 5-11; both ends of the rear crossbeam 9 are respectively connected to two rear longitudinal beams 5-12; the longitudinal beam bodies 5-1 in the two single longitudinal beam assemblies and the crossbeam assembly enclose a "Lü" character structure; the main structure of the subframe assembly of the present invention is in the shape of a "Lü" character, greatly increasing the overall structural strength of the front subframe assembly.

[0045] In addition, in the present invention, the front crossbeam 1, the middle crossbeam 17 and the rear crossbeam 9 are all assembled and welded structures, mainly assembled by two arc-shaped plate parts with different sizes, as shown in the appendix Figure 6-8 shown; the two arc-shaped plate parts overlap each other and are connected by welding at the overlapping part. Such a design method facilitates the production of the front crossbeam 1, the middle crossbeam 17 and the rear crossbeam 9.

[0046] Furthermore, the longitudinal beam assembly in this invention also includes a mounting arm mechanism 3-6 disposed on the longitudinal beam body 1-1. The mounting arm mechanism 3-6 includes a mounting arm disposed on the longitudinal beam body 1-1. The mounting arm is equivalent to adding a connecting component to the longitudinal beam body 1-1, which facilitates the subsequent connection between the subframe and the vehicle body. In actual design, the mounting arm is arc-shaped. There is a certain gap between the mounting arm and the upper end face of the longitudinal beam body 1-1 to avoid installation interference between the longitudinal beam body 1-1 and the vehicle body during actual installation and fixing. At the same time, the mounting arm in this invention provides a raised arrangement, so that the subframe assembly and the vehicle body have a certain distance, which facilitates the arrangement of other components between them.

[0047] In this invention, the mounting arm is connected to the main body of the longitudinal beam by welding a flange at its lower end.

[0048] Furthermore, in this invention, each mounting arm is provided with a T-shaped sleeve 3-61; in this invention, the T-shaped sleeve 3-61 acts as an external connector, which is convenient to be connected to the vehicle body by bolts or welding, thus facilitating the connection between the mounting arm and the vehicle body. In addition, in this invention, the T-shaped sleeve 3-61 is provided with a hobbing tooth on the side near the vehicle body; the hobbing tooth increases the friction between the T-shaped sleeve 3-61 and the vehicle body, thus suppressing the large acceleration during rapid acceleration and deceleration of the electric vehicle, which causes the subframe to wobble and make abnormal noise.

[0049] Furthermore, in this invention, the front crossbeam 1, the middle crossbeam 17, and the rear crossbeam 9 are spaced apart; the front crossbeam 1 is connected to two oppositely distributed front longitudinal beams 5-11; the middle crossbeam 17 and the rear crossbeam 9 are respectively connected to the rear longitudinal beams 5-12 at both ends; the arrangement of the front crossbeam 1, the middle crossbeam 17, and the rear crossbeam 9 increases the lateral strength of the subframe, and subsequently, it cooperates with the two longitudinal beam bodies 1-1 to form a L-shaped structure, greatly increasing the strength between the longitudinal beam bodies 1-1; in actual arrangement, because the strength of the front longitudinal beam 5-11 is less than that of the rear longitudinal beam 5-12, the middle crossbeam 17 and the rear crossbeam 9 are connected to the rear longitudinal beam 5-12. This design greatly ensures the structural strength of the rear section of the subframe, thereby ensuring the structural strength of the area where the motor is located at the rear end of the subframe, and reducing the impact damage to the electric vehicle motor caused by subframe deformation.

[0050] Furthermore, the rear longitudinal beam 5-12 described in this invention is provided with multiple motor connecting shafts 5-3; the present invention facilitates the connection between the subsequent subframe and the motor through the setting of the motor connecting shafts 5-3.

[0051] Furthermore, in this invention, a steering gear connecting shaft 5-2 is provided on the front longitudinal beam 5-11; the provision of the steering gear connecting shaft 5-2 facilitates the subsequent arrangement of the steering gear.

[0052] By setting the motor connecting shaft 5-3 and the steering gear connecting shaft 5-2 as described above, this invention is equivalent to arranging the mounting points of the motor and steering gear on the subframe. At the same time, in actual design, by optimizing the number and position of the motor connecting shaft 5-3 and the steering gear connecting shaft 5-2, the subframe assembly can be equipped with motors or steering gears of various models and sizes, greatly increasing the application range of the subframe assembly.

[0053] Furthermore, the front subframe assembly in this invention also includes a swing arm connecting mechanism, which includes a lower swing arm fixing bracket. The lower swing arm fixing bracket facilitates the installation and connection of the lower swing arm. Additionally, the lower swing arm fixing bracket is connected to the front longitudinal beam 5-11; this arrangement increases the strength of the front longitudinal beam 5-11 to a certain extent. Simultaneously, the vertical cross-section of the lower swing arm fixing bracket is Ω-shaped. Through this Ω-shaped lower swing arm fixing bracket structural design, the invention significantly increases the structural strength and rigidity of the lower swing arm fixing bracket, while avoiding localized stress concentration defects during welding.

[0054] Furthermore, in this invention, a reinforcing plate 18 is provided at the connection between the front longitudinal beam 5-11 and the rear longitudinal beam 5-12; the provision of the reinforcing plate 18 increases the stability of the connection between the front longitudinal beam 5-11 and the rear longitudinal beam 5-12, and ensures the strength of the connection between the front longitudinal beam 5-11 and the rear longitudinal beam 5-12.

[0055] Furthermore, in this invention, each of the longitudinal beams 5-1 is provided with a front lower crossbeam mounting seat 2 at its end. The front lower crossbeam mounting seat 2 is connected to the longitudinal beam 5-1 by corner welding. The present invention facilitates the arrangement and placement of the front lower crossbeam by setting the front lower crossbeam mounting seat 2.

[0056] A method for assembling a front subframe assembly of an automobile, the assembly method comprising the following steps:

[0057] Step 1: First, assemble the two individual longitudinal beam assemblies and the crossbeam assembly separately;

[0058] Step 2: After completing Step 1, assemble the two individual longitudinal beam assemblies with the transverse beam assembly;

[0059] Step 3: After completing Step 2, a front subframe assembly is assembled. If you need to assemble the front subframe assembly again, repeat Steps 1-2.

[0060] The present invention, through the above-described assembly method, enables the main body of the front subframe assembly to be assembled into three parts, and then the three parts are assembled as a whole. This assembly method greatly improves the assembly efficiency of the subframe assembly.

[0061] specific:

[0062] The full frame assembly disclosed in this invention is mainly used in the double wishbone suspension system of electric vehicles.

[0063] Reference Figure 1 The front subframe includes a front crossbeam 1, a rear crossbeam 9, and a middle crossbeam 17; in this invention, the longitudinal beam assembly includes a longitudinal beam body 1-1; the longitudinal beam body 1-1 includes two relatively distributed individual longitudinal beam assemblies; the two individual longitudinal beam assemblies are connected by a crossbeam assembly.

[0064] The single longitudinal beam assembly includes a longitudinal beam body 5-1; the longitudinal beam body 5-1 includes a front longitudinal beam 5-11 and a rear longitudinal beam 5-12; the front longitudinal beam 5-11 and the rear longitudinal beam 5-12 are connected; the longitudinal beam bodies 5-1 are referred to as the left longitudinal beam body 5-1 and the right longitudinal beam body 5-1 due to their different distribution positions, and the left longitudinal beam body 5-1 and the right longitudinal beam body 5-1 are distributed relative to each other.

[0065] Meanwhile, in this invention, the left longitudinal beam 5-1 includes a front section 13 (crushable section) of the left longitudinal beam and a rear section 10 (reinforcing section) of the left longitudinal beam; here, the front section 13 (crushable section) of the left longitudinal beam is equivalent to the front section of the longitudinal beam 5-11 in the left longitudinal beam 5-1 mentioned above; the rear section 10 (reinforcing section) of the left longitudinal beam is equivalent to the rear section of the longitudinal beam 5-12 in the left longitudinal beam 5-1 mentioned above.

[0066] The right longitudinal beam 5-1 includes the front section (crushable section) and the rear section (reinforced section) of the right longitudinal beam; here, the front section (crushable section) of the right longitudinal beam is equivalent to the front section of the longitudinal beam 5-11 in the right longitudinal beam 5-1 mentioned above; the rear section (reinforced section) of the right longitudinal beam is equivalent to the rear section of the longitudinal beam 5-12 in the right longitudinal beam 5-1 mentioned above.

[0067] Meanwhile, an installation arm mechanism 3-6 is provided on the main body 1-1 of the longitudinal beam. The installation arm mechanism 3-6 includes an installation arm provided on the main body 1-1 of the longitudinal beam. The installation arm is arc-shaped. The installation arms are installed in different positions, namely, a curved arm 3 for the left front of the subframe, a curved arm 6 for the middle right of the subframe, a curved arm 12 for the left middle, and a curved arm 15 for the left front.

[0068] Meanwhile, the front subframe assembly in this invention also includes a swing arm connecting mechanism, which includes a lower swing arm fixing bracket. The lower swing arm fixing bracket is divided into: front lower swing arm fixing bracket 4, right rear lower swing arm fixing bracket 7, left rear lower swing arm fixing bracket 11, and left front lower swing arm fixing bracket 14, depending on the setting position.

[0069] Define the vehicle length direction as the first direction X, the vehicle width direction as the second direction Y, and the vehicle height direction as the third direction Z. The three directions are perpendicular to each other. Establish a rectangular coordinate system based on the first, second, and third directions. The origin of the rectangular coordinate system is located at the midpoint of the line connecting the centers of the two front wheels.

[0070] As shown in Figure 2, Z-direction connecting shafts are established respectively; here, the Z-direction connecting shafts are T-shaped sleeves 3-61 respectively on the mounting arm or the main body of the longitudinal beam 1-1. There are 6 T-shaped sleeves 3-61 on the main body of the longitudinal beam 1-1, namely Z1, Z2, Z3, Z4, Z5, and Z6; in subsequent use, the subframe is fixed to the vehicle body by bolts passing through each T-shaped sleeve 3-61.

[0071] Meanwhile, a steering gear connecting shaft 5-2 is provided on the main body 1-1 of the longitudinal beam. The steering gear connecting shafts 5-2 are Z7 and Z10 respectively. In actual use, Z7 and Z10 are used to fix the subframe and the DP steering gear.

[0072] In addition, eight motor connecting shafts 5-3 are provided on the main body of the longitudinal beam 1-1, namely Z8 (4 shafts) and Z9 (4 shafts); the above-mentioned motor connecting shafts 5-3 are used for connecting and fixing the motor suspension bracket to the subframe. The direction of the connecting shafts is Z-axis, and the connecting shafts are parallel to each other.

[0073] As shown in Figure 3, the subframe connecting shaft Z6 is fixed to the vehicle body with bolts, and the coordinates of key point 101 are -377, -477, 30; the fixing point of the left front lower control arm bracket is connected to the subframe through a rubber bushing, and the coordinates of key point 102 are -310.04, -413.7, -137.04; the fixing point of the middle left curved arm of the subframe to the vehicle body, and the coordinates of key point 103 are -77, -425, 64.5; the fixing point of the left rear lower control arm bracket is connected to the subframe through a rubber bushing, and the coordinates of key point 104 are 3.501, -405.15, -130.21; the fixing point of the left rear of the subframe to the vehicle body, and the coordinates of key point 105 are 276, -414, -93.6; the coordinates of the fixing key points 106, 107, 108, 109, and 110 on the right side correspond exactly to those on the left side, but the Y-coordinates are reversed.

[0074] To enhance vehicle collision safety, this invention adds a front bumper lower crossbeam mounting seat 2 to the subframe. The front bumper lower crossbeam mounting seat 2 is press-fitted with three bolts and then welded to the left and right longitudinal beams 5-1 through an interference fit. By longitudinally arranging corner welds, the collision load-bearing capacity is strengthened.

[0075] The fixed curved arms of the front subframe and the body are set on the left and right longitudinal beams 5-1 and fixed by welding reinforced curved arm stamping parts. The connection and fixing points of the curved arms and the body are matched and fitted by welded T-shaped sleeves 3-61. The end face of the T-shaped sleeves 3-61 is added with hobbing teeth to increase the friction of the contact surface and suppress the subframe lurching and abnormal noise caused by the large acceleration during the rapid acceleration and deceleration of the electric vehicle. The front section of the longitudinal beam 5-11 in the middle of the front and rear mounting arms is designed as a crushable section, which allows this section to crush and bend in the event of a collision, improving the safety of the whole vehicle and preventing damage to the electric vehicle battery.

[0076] The left and right front and rear lower swing arm fixing brackets are designed as Ω-shaped stamped parts and welded to the left and right longitudinal beams 5-1. The Ω-shaped stamped parts fully increase the strength and rigidity of the structure, while avoiding the defects of local stress concentration during welding.

[0077] As shown in Figure 4, the subframe structure of this invention facilitates welding and manufacturing. The main assembly can be divided into three groups: I, II, and III. Group I uses the left longitudinal beam 1-1 to weld the left-side sub-components into small modules. Group III uses the right longitudinal beam 1-1 to weld the right-side sub-components into small modules. Groups I and III are then welded together into the main assembly via the front, middle, and rear crossbeams 9 in Group II. This arrangement design improves the stability of the subframe welding dimensions while reducing the complexity of welding tooling and lowering costs. The rational arrangement of the longitudinal positions of the front, middle, and rear crossbeams significantly enhances the torsional stiffness and strength of the front subframe.

[0078] The left and right side longitudinal beam sections are structurally designed as reinforcements of the subframe longitudinal beams, which helps to strengthen the longitudinal load-bearing capacity of the subframe during a vehicle collision, making it less prone to deformation and avoiding impact damage to the electric vehicle battery caused by subframe deformation.

[0079] The invention features a front subframe L-shaped structure design for a double wishbone suspension, with the motor mounting bracket separately fixed to the front subframe by bolts, allowing for the efficient and effective arrangement of multiple motors and enabling platform-based compatibility across multiple vehicle models.

[0080] This invention achieves the following objectives through the design of the mounting hard points of the subframe and the axial arrangement of the frame structure connection points: It meets the target requirements for stiffness, strength, and modal characteristics of the front subframe assembly, providing high lateral stiffness and improving the overall vehicle handling comfort; the connection and matching of the crossbeams and longitudinal beams, along with the design of crushing and reinforcing sections in the longitudinal beams, significantly enhances the collision safety of the front subframe for electric vehicles; the platform utilizes a DP steering gear, which is suitable for various drive motors with a L-shaped subframe structure, making it universal across multiple motor platforms, effectively expanding the battery X-axis layout space, and minimizing costs.

[0081] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. An assembling method of an automobile front subframe assembly, characterized in that, the automobile front subframe assembly comprises a longitudinal beam assembly and a cross beam assembly; the longitudinal beam assembly comprises a longitudinal beam main body, the longitudinal beam main body comprises two single longitudinal beam assemblies which are oppositely distributed; the two single longitudinal beam assemblies are connected through the cross beam assembly; the single longitudinal beam assembly comprises a longitudinal beam body; the longitudinal beam body comprises a front section longitudinal beam and a rear section longitudinal beam; the front section longitudinal beam is connected with the rear section longitudinal beam; the cross beam assembly comprises a front cross beam, a middle cross beam and a rear cross beam; the front cross beam is connected at two ends thereof with the two front section longitudinal beams respectively; the rear cross beam is connected at two ends thereof with the two rear section longitudinal beams respectively; the front cross beam, the middle cross beam and the rear cross beam are spacedly distributed; the front cross beam is connected with the two oppositely distributed front section longitudinal beams; the middle cross beam and the rear cross beam are connected at two ends thereof with the rear section longitudinal beams respectively; the strength of the front section longitudinal beam is required to be less than that of the rear section longitudinal beam; the longitudinal beam body of the two single longitudinal beam assemblies and the cross beam assembly form a Chinese character "LY" type structure; the front section longitudinal beam serves as a collapse section, and the rear section longitudinal beam serves as a reinforcing member; the front cross beam, the middle cross beam and the rear cross beam are all assembled and welded structures; the front section longitudinal beam and the rear section longitudinal beam are provided with a reinforcing plate at a connection position therebetween; the assembling method comprises the following steps: Step 1: two single longitudinal beam assemblies and a cross beam assembly are assembled respectively; the front cross beam, the middle cross beam and the rear cross beam are all assembled through two arc-shaped plate members of different sizes; the two arc-shaped plate members are overlapped with each other and are connected through welding at the overlapped position; Step 2: after Step 1 is completed, the two single longitudinal beam assemblies and the cross beam assembly are assembled; Step 3: after Step 2 is completed, one front subframe assembly is assembled, if it is required to assemble the front subframe assembly repeatedly, Steps 1-2 can be repeated.

2. The front subframe assembly of claim 1, wherein, the longitudinal beam assembly further comprises a mounting arm mechanism arranged on the longitudinal beam main body, the mounting arm mechanism comprises a mounting arm arranged on the longitudinal beam main body; the mounting arm is arc-shaped.

3. The automotive front subframe assembly of claim 2, wherein a T-shaped sleeve is arranged on each mounting arm; the T-shaped sleeve is provided with a gear hob near a side close to a vehicle body.

4. The automotive front subframe assembly of claim 1, wherein a plurality of motor connecting shafts are arranged on the rear section longitudinal beam.

5. The automotive front subframe assembly of claim 1, wherein, a steering engine connecting shaft is arranged on the front section longitudinal beam.

6. The automotive front subframe assembly of claim 1, wherein, the front subframe assembly further comprises a swing arm connecting mechanism, the swing arm connecting mechanism comprises a lower swing arm fixed support, the lower swing arm fixed support is connected with the front section longitudinal beam; the lower swing arm fixed support is in an Ω shape in a vertical section.

7. The automotive front subframe assembly of claim 1, wherein, a front bumper lower cross beam mounting seat is arranged at an end of each longitudinal beam body; the front bumper lower cross beam mounting seat is connected with the longitudinal beam body through corner welding.

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