Closed torsion beam assembly

Abstract

The application relates to the technical field of automobile parts, and particularly discloses a closed torsion beam assembly, which comprises a cross beam and longitudinal arms fixed on the two sides of the cross beam, the longitudinal arm comprises a sleeve lap joint section, a cross beam lap joint section and a hub bracket lap joint section, the sleeve lap joint section is used for fixing a sleeve, the cross beam lap joint section is used for lap joint fixing with the cross beam, the hub bracket lap joint section is used for fixed connection with a hub bracket, a damping mounting hole penetrating through the longitudinal arm is arranged on the position of the cross beam lap joint section close to the hub bracket lap joint section, a damping mounting plate is fixed on the damping mounting hole, and the damping mounting plate penetrates through the damping mounting hole. The scheme is used to solve the problem of low longitudinal arm strength caused by the notch arranged at the end of the torsion beam longitudinal arm.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile parts, and in particular to a closed torsion beam assembly. Background Art

[0002] Automobile torsion beams are popular because of their simple structure, easy adjustment and maintenance, simple manufacturing, and the large space they free up for the rear seats and trunk of the vehicle. Among the current automobile torsion beams, the most mainstream is the closed torsion beam with a closed cross-section on the crossbeam.

[0003] A closed torsion beam includes a crossbeam and longitudinal arms on both sides of the crossbeam. The longitudinal arms are connected to the wheels through wheel hub brackets, and the force acting on the wheels is directly transmitted to the entire torsion beam through the corresponding longitudinal arms. Among the current torsion beam longitudinal arms, there is a method of forming by sheet metal stamping and rolling, such as the "Torsion Beam Longitudinal Arm, Torsion Beam Assembly and Automobile" with Chinese Patent Publication No. CN208698416U. In this technology, the longitudinal arm is formed by rolling the sheet metal after stamping, so that the longitudinal arm forming method is simple and convenient. However, in this patented technology, a notch is opened on one side of the end of the longitudinal arm for installing the shock absorber bracket, and the setting of the notch makes the strength of the longitudinal arm lower. Summary of the Invention

[0004] The present invention aims to provide a closed torsion beam assembly to solve the problem of low strength of the torsion beam longitudinal arm caused by notches at the ends of the longitudinal arms.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The closed torsion beam assembly includes a crossbeam and longitudinal arms fixed on both sides of the crossbeam. The longitudinal arms include a sleeve overlapping section, a crossbeam overlapping section and a wheel hub bracket overlapping section. The sleeve overlapping section is used to fix the sleeve, the crossbeam overlapping section is used to overlap and fix with the crossbeam, and the wheel hub bracket overlapping section is used to be fixedly connected with the wheel hub bracket. A shock-absorbing mounting hole that passes through the longitudinal arm is provided at a position of the crossbeam overlapping section near the wheel hub bracket overlapping section. A shock-absorbing mounting plate is fixed on the shock-absorbing mounting hole, and the shock-absorbing mounting plate passes through the shock-absorbing mounting hole.

[0007] The principle and advantages of this solution are: when adopting this solution, the shock-absorbing mounting plate is fixed on the shock-absorbing mounting hole, so that the shock-absorbing mounting plate is away from the end of the longitudinal arm, and there is no need to open a notch in the end of the longitudinal arm as in the prior art, thereby ensuring the strength of the end of the longitudinal arm; at the same time, the shock-absorbing mounting plate is located on the cross-beam overlap section in the middle section of the longitudinal arm, and the shock-absorbing mounting plate passes through the longitudinal arm, so that the shock-absorbing mounting plate not only facilitates the installation of the shock absorber, but also makes the shock-absorbing mounting plate equivalent to a structure forming a reinforcing rib in the middle of the longitudinal arm, greatly improving the strength and lateral stiffness of the torsion beam longitudinal arm.

[0008] Preferably, as an improvement, a reinforcing plate is fixed to the longitudinal arm within the wheel hub bracket overlap section to further improve the lateral stiffness of the longitudinal arm.

[0009] Preferably, as an improvement, a wheel hub bracket and a spring tray bracket are fixed to the wheel hub bracket overlap section of the longitudinal arm, and the wheel hub bracket and the spring tray bracket are located on both sides of the wheel hub bracket overlap section.

[0010] Preferably, as an improvement, the wheel hub bracket is fixed on the longitudinal arm position between the shock absorber mounting plate and the reinforcement plate; the reinforcement plate and the shock absorber mounting plate on the longitudinal arm where the wheel hub bracket is installed simultaneously strengthen the strength of the longitudinal arm, making the strength and lateral stiffness of the torsion beam higher.

[0011] Preferably, as an improvement, the cross-sectional area of ​​the location of the shock-absorbing mounting hole is the maximum cross-sectional area of ​​the longitudinal arm, so as to improve the strength of the location of the shock-absorbing mounting hole.

[0012] Preferably, as an improvement, the longitudinal arms and cross beams are both formed by drawing and flanging sheet materials before being folded together. Closing gaps are provided at the folding locations. The folding gaps of the cross beams are located at the top of the cross beams, and the folding gaps of the longitudinal arms are located on the side opposite the interface between the longitudinal arms and the cross beams. This solution simplifies and speeds the forming of the longitudinal arms and cross beams. Furthermore, by providing the folding gaps, the folding gaps of the cross beams are positioned as far away from the folding gaps of the longitudinal arms as possible, facilitating the overlap of the cross beams and longitudinal arms.

[0013] Preferably, as an improvement, the closing gap of the crossbeam is welded into a continuous gap by continuous welding. When adopting this solution, due to the large length of the torsion beam crossbeam, the conventional welding method adopts segmented welding, but the continuity between adjacent welds of segmented welding is poor, resulting in uneven weld quality, which is easy to cause local stress concentration and cannot meet the requirements of road test (the crossbeam cracks at the weld during the road test). At the same time, the arc starting and arc ending positions of adjacent weld segments are prone to insufficient weld penetration (especially after the back-off treatment after welding, the workpiece shrinks, and the insufficient weld penetration in some parts with greater stress is aggravated), which is prone to fatigue cracking during use. This solution changes the welding method to continuous welding, making the weld completely continuous, and does not have the problems of existing segmented welding.

[0014] Preferably, as an improvement, when the crossbeam is welded by continuous welding, the welded crossbeam has a processing allowance in the length direction. When welding, a small section is first welded or spot welded at the processing allowance position of the crossbeam, and then continuous welding is performed from the other end of the crossbeam gap until the entire gap is welded.

[0015] Beneficial effect: This solution can reduce the deformation caused by welding by first performing end welding at the end and then starting welding from the other end.

[0016] Preferably, as an improvement, the closing gap of the crossbeam does not exceed 1.0 mm, the plate thickness is 2.2-3.2 mm, and the welding penetration rate is not less than 60%.

[0017] Beneficial effect: This solution ensures the strength of welding by controlling the weld width, plate thickness and welding penetration rate during welding.

[0018] Furthermore, when the crossbeam gap is welded, the welding current is 245-255A, the arc voltage is 17-21V, and the welding speed is 70-90CM / min.

[0019] Beneficial Effects: Due to the long span and variable cross-section of the beam, the residual stresses in different locations of the beam after welding vary. If the welding parameters are not properly controlled, the beam deformation after welding may not meet the design requirements. This solution controls the welding current, arc voltage, and welding speed to achieve both rapid welding and uniform weld formation for welds with small surface changes and welds longer than 1 meter. This ensures that curved welds with spatially varying heights will not suffer from quality issues such as undercuts, weld bumps, arc craters, pores, slag inclusions, and cracks.

[0020] In addition, by controlling the welding parameters, it is helpful to reduce the heat-affected zone of the welding process, ensuring both small welding deformation and extremely small welding spatter. After welding is completed, there is no need for secondary processing of the weld or welding products, which greatly improves production efficiency.

[0021] Preferably, as an improvement, the crossbeam includes, from the middle to the ends, a middle section, a transition section, and an overlap section. The middle section has a U-shaped or V-shaped cross section, the overlap section has an oblate cross section, and the transition section gradually changes from the middle section's cross section to the oblate cross section of the overlap section. The crossbeam is provided with a weld avoidance groove located below the closing gap, which passes through the middle section and extends to the transition section. The design of the weld avoidance groove prevents welding on the stretched portion of the crossbeam during welding at the closed position of the crossbeam.

[0022] Preferably, as an improvement, the length of the middle section of the crossbeam is shorter than that of the transition section. When this solution is used, the transition section needs to transition from the shape of the middle section to the oblate structure of the overlapping section during draw forming. If the transition section is too short, it will be prone to cracking due to the stress of both longitudinal and transverse stretching. By setting the transition section longer, this solution allows the cross-section of the transition section to change more slowly, reducing the probability of cracking.

[0023] Preferably, as an improvement, the longitudinal arm forming includes the following steps:

[0024] Step 1: A tubular unclosed longitudinal arm is obtained by first stamping and drawing, then stamping and flanging, and finally stamping and rolling. After the process is completed, two longitudinal arms are connected together, and the hub bracket overlap sections of the two longitudinal arms are butted together to form a whole. The two longitudinal arms have symmetrical structures.

[0025] Step 2: Welding the closed gap of the conjoined longitudinal arm completed in step 1;

[0026] Step 3: Cut the welded conjoined longitudinal arm from the middle to obtain two finished longitudinal arms.

[0027] Beneficial effects: When this solution is adopted, the two longitudinal arms required for the torsion beam assembly are directly formed each time, which improves the production efficiency of the longitudinal arms. In addition, the two longitudinal arms on the same torsion beam assembly are formed simultaneously using the same mold, ensuring the quality consistency of the two longitudinal arms under the same torsion beam assembly, which is beneficial to improving the quality of the torsion beam assembly.

[0028] In addition, this solution also designs the shape of the longitudinal arm so that the stamped one-piece longitudinal arm is in the shape of a bow and arrow. The formed one-piece longitudinal arm has the smallest shape size at both ends (both ends are sleeve overlap sections) and the second largest shape size (two wheel hub bracket overlap sections), that is, the two intermediate variable cross-section sections are located between the two small sizes, which ensures that the deformation trend of the intermediate variable cross-section section after stamping is constrained by the small size shape at both ends, and the longitudinal arm end has a small size and basically no variable cross-section, so the shape size is very stable after forming, thereby greatly improving the size and accuracy of the intermediate variable cross-section section whose original shape structure was difficult to control, ensuring the size accuracy and shape accuracy of the longitudinal arm after stamping. In addition, since the deformation of the intermediate variable cross-section section of the longitudinal arm is restricted and not easily deformed, it also reduces the design requirements for welding auxiliary tooling during subsequent welding, which is conducive to the simplification of welding auxiliary tooling.

[0029] Preferably, as an improvement, step one specifically includes the following steps:

[0030] Drawing: Part of the longitudinal arm's profile is formed by stamping and drawing. The cross-section of the drawn part of the longitudinal arm is U-shaped.

[0031] Trimming: Punch and trim the drawn sheet to remove excess material and punch out a bevel on the edge of the sheet during trimming.

[0032] Stamping and flanging: The undrawn part of the sheet is stamped and flanging, and the cross section of the longitudinal arm is now U-shaped;

[0033] Final forming by stamping: The final forming die is used to directly stamp and close the free end of the longitudinal arm with a U-shaped cross-section. The final forming die includes an upper die and a lower die. The lower die is matched with the concave and convex part of the drawing part of the longitudinal arm. The upper die is provided with a cavity that matches the designed shape of the longitudinal arm. Guide inclined surfaces are provided on both sides of the cavity cross-section of the upper die. When the final forming die is closed, the bevel of the free end of the longitudinal arm automatically moves along the edge of the cavity of the upper die during the downward pressure of the upper die until the two free ends of the longitudinal arm are closed at the top of the cavity.

[0034] Beneficial effect: When this solution is adopted, the forming of part of the longitudinal arm surface is completed through one stamping and drawing. After the remaining part is trimmed to remove excess sheet material, it is directly formed by the final forming mold after stamping and flanging. Before final forming, there is no need to gradually shape the free end of the longitudinal arm. Instead, the oblique angle of the longitudinal arm's own side line guides the entire longitudinal arm free end to automatically move along the cavity surface of the upper mold. Even if the free end of the longitudinal arm rebounds after stamping, the free end side line of the longitudinal arm will move closer to the cavity after contacting the guiding inclined surface, and finally stick to the cavity surface to complete the final forming. The forming method is simple and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a structural diagram of embodiment 1 of the present invention.

[0036] Figure 2 for Figure 1 Schematic diagram of the structure of the middle crossbeam.

[0037] Figure 3 This is a schematic diagram of the structure of the first embodiment of the present invention after the crossbeam is flipped.

[0038] Figure 4 This is a schematic structural diagram of the first embodiment of the present invention after the crossbeam is cut off from the middle section.

[0039] Figure 5 This is a schematic structural diagram of the trailing arm after welding the sleeve, spring tray bracket and wheel hub bracket according to the first embodiment of the present invention.

[0040] Figure 6 for Figure 5 Top view of .

[0041] Figure 7 for Figure 5 Cross-sectional view of .

[0042] Figure 8 This is a process flow chart of the third longitudinal arm forming process according to an embodiment of the present invention.

[0043] Figure 9 Schematic diagram of the structure of the final forming mold used in step S4 of the third embodiment of the present invention.

[0044] Figure 10 A schematic structural diagram of the conjoined longitudinal arm obtained after step S4 in the third embodiment of the present invention. DETAILED DESCRIPTION

[0045] The following is further described in detail through specific implementation methods:

[0046] The figure marks in the drawings of the specification include: crossbeam 1, longitudinal arm 2, middle section 11, transition section 12, overlapping section 13, oil filling hole 131, weld avoidance groove 111, sleeve overlapping section 21, crossbeam overlapping section 22, wheel hub bracket overlapping section 23, sleeve 3, shock absorber mounting plate 4, reinforcement plate 5, wheel hub bracket 6, spring tray bracket 7.

[0047] Example 1

[0048] Combine Figures 1 to 7 As shown, the closed torsion beam assembly comprises a crossbeam 1 and trailing arms 2 fixed to either side of the crossbeam 1. Both the crossbeam 1 and the trailing arms 2 are formed from sheet metal through drawing and flanging. The gaps between the flanging seams are welded to form continuous welds. The continuous welds of the trailing arms 2 are located on the opposite side of the crossbeam 1. This allows the crossbeam 1 and trailing arms 2 to overlap without completely avoiding the welds of the trailing arms 2. This ensures that the torsion beam assembly is simple to form and that stresses generated by the welds are not affected by each other, which contributes to the overall strength of the torsion beam.

[0049] Combine Figures 2 to 4 The crossbeam 1 includes, from the middle to the ends, a middle section 11, a transition section 12, and an overlap section 13. The cross section of the middle section 11 is U-shaped or V-shaped. In this embodiment, the cross section of the middle section 11 is similar to a U-shape, and the cross section of the overlap section 13 is oblate. The cross section of the transition section 12 gradually changes from the cross section of the middle section 11 to the oblate shape of the overlap section 13. The crossbeam 1 forms a cavity between the drawn portion and the flanged portion. The minimum gap between the drawn portion and the flanged portion is greater than 0.5 times the thickness of the sheet metal. That is, in the cross section of the middle section 11, the minimum gap between the drawn portion and the flanged portion in the cavity within the middle section 11 is greater than 0.5 times the thickness of the sheet metal. An oil injection hole 131 is formed by punching on the overlap section 13 of the crossbeam 1; this facilitates the airtightness testing of the crossbeam 1 and the injection of lubricating oil through the oil injection hole 131. This solution sets a gap so that the flanged formed part and the drawn formed part in the middle section 11 with the smallest cross-section of the beam 1 will not touch each other, thereby greatly reducing the noise generated by the contact between the two. At the same time, the lubricating oil is injected into the beam 1 from the oil filling hole 131 to further ensure that there is no friction between the two. Even if the flanged formed part and the drawn formed part touch each other under a great external force, the noise generated by the friction will be reduced due to the presence of the lubricating oil.

[0050] The length of the middle section 11 is smaller than that of the transition section 12 so that the transition section 12 is long enough to ensure that the cross section of the transition section 12 changes more slowly, thereby reducing the probability of cracking during the forming process of the beam 1 and improving the fatigue strength of the beam 1.

[0051] The joints of beam 1 are sealed using continuous welding, resulting in a continuous weld. With this solution, due to the length of beam 1, conventional welding uses segmented welding. However, the continuity between adjacent welds in segmented welding is poor, resulting in uneven weld quality and prone to localized stress concentration. Furthermore, insufficient weld penetration is common at the arc starting and arc ending points between adjacent weld segments, making fatigue cracking a common problem during use. By switching to continuous welding, this solution ensures a completely continuous weld, eliminating the problems associated with conventional segmented welding.

[0052] A weld avoidance groove 111 is formed on the drawn crossbeam 1. This groove 111 extends through the middle section 11 and into the transition section 12. The minimum spacing between the bottom of the groove 111 and the closed portion of the crossbeam 1 is greater than 4mm. The design of the weld avoidance groove 111 prevents welding at the closed portion from contacting the drawn portion. Furthermore, the spacing minimizes the effect of welding heat on the drawn portion of the middle section 11, reducing residual stress caused by heat.

[0053] The overlapping section 13 of the crossbeam 1 is thicker than the middle section 11, and the overlapping section 13 can overlap the upper surface and the lower surface of the longitudinal arm 2 at the same time, and the overlapping section 13 is overlapped at the position of the longitudinal arm 2 where there is no weld; this solution enables the overlapping section 13 to overlap with the longitudinal arm 2 with a longer circumference (the two are generally overlapped by welding), ensuring the connection strength between the crossbeam 1 and the longitudinal arm 2, eliminating the process of adding a reinforcement structure between the crossbeam 1 and the longitudinal arm 2, reducing the production cost of the torsion beam and being more conducive to the lightweighting of the torsion beam.

[0054] Combine Figures 5 to 7 The trailing arm 2 includes, in the axial direction, a sleeve overlapping section 21, a crossbeam overlapping section 22, and a wheel hub bracket overlapping section 23. The sleeve overlapping section 21 is used to secure the sleeve 3, the crossbeam overlapping section 22 is used for fixed overlap with the crossbeam 1, and the wheel hub bracket overlapping section 23 is used for fixed connection with the wheel hub bracket 6. A shock absorber mounting hole is cut into the crossbeam overlapping section 22 near the wheel hub bracket overlapping section 23, penetrating the trailing arm 2. A shock absorber mounting plate 4 is welded to the shock absorber mounting hole, which extends through the square shock absorber mounting hole. The cross-sectional area of ​​the shock absorber mounting hole represents the maximum cross-sectional area of ​​the trailing arm 2.

[0055] A reinforcement plate 5 is welded to the wheel hub bracket overlap section 23 of the trailing arm 2. This reinforcement plate 5 is machined with weight-reducing holes. A wheel hub bracket 6 and a spring tray bracket 7 are fixed to the wheel hub bracket overlap section 23, located on either side of the wheel hub bracket overlap section 23. The reinforcement plate 5 directly faces the connection between the wheel hub bracket 6 and the wheel hub bracket overlap section 23.

[0056] In this embodiment, by securing the shock-absorbing mounting plate 4 to the shock-absorbing mounting hole and welding the reinforcement plate 5 to the interior of the trailing arm 2, the shock-absorbing mounting plate 4 and the reinforcement plate 5 simultaneously reinforce the tubular structure of the trailing arm 2, significantly increasing the rigidity and strength of the trailing arm 2. Furthermore, the provision of the shock-absorbing mounting hole utilizes the internal space of the trailing arm 2, facilitating the welding and securing of the shock-absorbing mounting plate 4 to the trailing arm 2 and improving the connection strength of the shock-absorbing mounting plate 4 to the trailing arm 2.

[0057] Example 2

[0058] The second embodiment further improves the welding of the crossbeam based on the first embodiment, as follows:

[0059] When the crossbeam is welded by continuous welding, the welded crossbeam has a processing allowance in the length direction. When welding, a small section is first welded at the processing allowance position of the crossbeam. The length of the welded small section is less than the length of the processing allowance, so that the welded small section will not exceed the processing allowance position. Then, continuous welding is started from the other end of the crossbeam gap until the entire gap is welded.

[0060] In this embodiment, the crossbeam gap does not exceed 1.0 mm, and the plate thickness is 2.2-3.2 mm (the plate is made of high-strength steel, such as high-strength CP800 steel). CMT welding is performed using a welding penetration of no less than 60%. The welding current is controlled at 245-255 A, the arc voltage at 17-21 V, and the welding speed at 70-90 cm / min. The welding wire diameter is 1.2 mm.

[0061] Because the beam targeted by this embodiment is relatively long, conventional welding methods are all segmented welding. However, simply using segmented welding cannot fully meet the road test requirements. Some beams cannot meet the design strength and stiffness requirements. When using CMT cold metal transfer technology for welding, due to the long weld seam and the undulations in the weld seam, there are still cases of continuous welding quality failure in multiple tests (see the welding test table below). The most common situation is that the penetration depth cannot meet the standard, resulting in unqualified weld quality. For this reason, the inventors have repeatedly adjusted the welding current, arc voltage and welding speed, and finally solved the problems of the existing technology, achieving both rapid welding and meeting the high quality requirements of the weld seam.

[0062] Welding test table

[0063]

[0064]

[0065] Note: The plate thickness used for welding in this test table is 2.6mm. Qualified penetration includes penetration rate of not less than 60%, uniform width and uniform weld height.

[0066] Example 2

[0067] Combine Figures 8 to 10 In the second embodiment, the forming process before welding of the trailing arm is improved as follows based on the first embodiment, specifically:

[0068] S1. Drawing: The profile of the longitudinal arm close to the crossbeam side is formed by stamping and drawing. At this time, the cross-section of the drawn portion of the longitudinal arm is U-shaped. In this process, two longitudinal arms are drawn simultaneously on a sheet metal. During the drawing, the two longitudinal arms are structurally symmetrical, and the hub bracket overlap sections of the two longitudinal arms are connected into one, forming a conjoined longitudinal arm. In order to prevent wrinkles from occurring at the end positioning section with a smaller cross-sectional size of the conjoined longitudinal arm, drawing protrusions are simultaneously drawn on the sheet metal. The drawing protrusions are located on both sides of the fixed cross-sectional section of the hub bracket overlap section in the width direction. The length of the drawn hub bracket overlap section is at least 5 mm longer than the design size of the longitudinal arm, forming a processing allowance in the middle of the conjoined longitudinal arm. The drawn portion of the conjoined longitudinal arm is bow-shaped in the length direction.

[0069] S2, trimming: Punch and trim the sheet material that has completed S1 to remove excess material, and at the same time, punch out a bevel on the edge of the sheet material during trimming. In this step, the size of the trimmed edge is compensated according to the change in the closing gap after the final forming in step S4. The perimeter of the corresponding section is increased for locations with large gaps after closing, while the perimeter of the corresponding section is reduced for locations with small gaps or overlaps, to ensure that the gap width is uniform after subsequent closing.

[0070] S3. Stamping and flanging: The undrawn part of the plate is stamped and flanging, and the cross section of the longitudinal arm is U-shaped at this time.

[0071] S4, stamping final forming: Use the final forming die to directly stamp the free end of the U-shaped longitudinal arm to close the longitudinal arm, and combine Figure 9 The final forming mold consists of an upper and lower mold. The lower mold has a concave-convex fit with the drawn portion of the trailing arm. The upper mold has a cavity that matches the designed shape of the conjoined trailing arm. Guided surfaces are located on both sides of the upper mold cavity cross-section. When the final forming mold is closed, as the upper mold presses downward, the bevel of the free end of the conjoined trailing arm automatically moves along the edge of the upper mold cavity until the two free ends of the trailing arm close together at the top of the cavity. The gap after closing, formed by the bevel fit, forms a V-shaped groove, facilitating subsequent welding. The finished conjoined trailing arm takes on a bow-and-arrow shape.

[0072] S5. Welding: Welding is performed at the closed position of the conjoined longitudinal arm.

[0073] S6. Cut the welded conjoined longitudinal arm from the middle to obtain two longitudinal arms.

[0074] The longitudinal arm formed by using this embodiment greatly improves the production efficiency of the longitudinal arm, and two longitudinal arms with exactly the same structural shape can be produced at one time. At the same time, the production steps of the longitudinal arm are combined with the structural design of the longitudinal arm itself, so that the connected longitudinal arm relies on its own shape to constrain the deformation trend caused by stamping, which greatly improves the dimensional accuracy and shape accuracy of the longitudinal arm after stamping, which is conducive to the simplification of welding tooling and the improvement of welding quality during welding.

[0075] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A closed torsion beam assembly, comprising a crossbeam and longitudinal arms fixed on both sides of the crossbeam. The longitudinal arms comprise a casing overlap section, a crossbeam overlap section, and a hub bracket overlap section. The casing overlap section is used to secure the casing, the crossbeam overlap section is used to overlap and secure the crossbeam, and the hub bracket overlap section is used to securely connect the hub bracket. The following features are present: A shock-absorbing mounting hole that passes through the longitudinal arm is provided at a position of the crossbeam overlap section close to the wheel hub bracket overlap section, a shock-absorbing mounting plate is fixed on the shock-absorbing mounting hole, and the shock-absorbing mounting plate passes through the shock-absorbing mounting hole; The crossbeam is formed by drawing and flanging the plate and then closing it together. There is a closing gap at the closing position. The closing gap of the crossbeam is located at the top of the crossbeam. The closing gap of the crossbeam is welded into a continuous gap by continuous welding. When continuous welding is used to weld the gap of the beam, there is a processing allowance in the length direction of the welded beam. When welding, a small section is welded or spot welded at the processing allowance position of the beam first, and then continuous welding is started from the other end of the beam gap until the entire gap is welded; The closing gap of the beam shall not exceed 1.0mm, the plate thickness shall be 2.2-3.2mm, and the welding penetration rate shall not be less than 60%; When welding the beam gap, the welding current is 245-255A, the arc voltage is 17-21V, and the welding speed is 70-90CM / min.

2. The closed torsion beam assembly according to claim 1, characterized in that: A reinforcement plate is fixed to the longitudinal arm in the overlapping section of the wheel hub bracket.

3. The closed torsion beam assembly according to claim 2, characterized in that: The wheel hub bracket and the spring tray bracket are fixed on the wheel hub bracket overlap section of the longitudinal arm, and the wheel hub bracket and the spring tray bracket are located on both sides of the wheel hub bracket overlap section.

4. The closed torsion beam assembly according to claim 3, characterized in that: The wheel hub bracket is fixed on the longitudinal arm position between the shock-absorbing mounting plate and the reinforcement plate.

5. The closed torsion beam assembly according to claim 1, characterized in that: The cross-sectional area of ​​the location of the shock-absorbing mounting hole is the maximum cross-sectional area of ​​the longitudinal arm.

6. The closed torsion beam assembly according to claim 1, characterized in that: The longitudinal arms are formed by drawing and flanging plates and then closing them together. There are closing gaps at the closing positions, and the closing gaps of the longitudinal arms are located on the opposite side of the butt joint between the longitudinal arms and the cross beam.

7. The closed torsion beam assembly according to claim 6, characterized in that: The crossbeam includes a middle section, a transition section and an overlapping section from the middle to both ends. The cross section of the middle section is U-shaped or V-shaped, the cross section of the overlapping section is oblate, and the cross section of the transition section gradually changes from the cross-sectional shape of the middle section to the oblate shape of the overlapping section. The crossbeam is provided with a weld avoidance groove located below the closing gap, which runs through the middle section and extends to the transition section.

8. The closed torsion beam assembly according to claim 7, characterized in that: The length of the middle section of the cross beam is smaller than the length of the transition section.

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