An x-arm for a vehicle rear suspension system and a method of designing the same

Abstract

The application discloses an X-shaped arm for a vehicle rear suspension system and a design method thereof, and mainly relates to the technical field of automobile suspensions. The X-shaped arm comprises a body and a reinforcing rib, the upper portion of the body is provided with a short connecting arm, the lower portion of the body is provided with a long connecting arm, the reinforcing rib is arranged at the left and right sides of the body, and the body is in a symmetrical structure from top to bottom. The X-shaped arm has the advantages of modularization and light weight, and the number and weight of parts of the automobile rear suspension system are reduced.

Description

Technical Field

[0001] This invention relates to the field of automotive suspension technology, specifically to an X-arm for a vehicle rear suspension system and its design method. Background Technology

[0002] Lightweighting and modularization have become the development direction for various truck manufacturers. Currently, lightweighting is mainly based on structural design, materials, and processes.

[0003] Traditional automobiles use a thrust rod + stabilizer bar structure. The thrust rod transmits lateral and longitudinal forces, while the stabilizer bar improves the vehicle's anti-roll capability. Due to the complex manufacturing process and large number of parts of the thrust rod and stabilizer bar, the cost and weight are high. The X-arm, on the other hand, serves the purposes of both a thrust rod and a stabilizer bar, and has the advantages of modularity and lightweight design. It reduces the number of parts and weight of the rear suspension system, while its roll stiffness is much greater than that of the traditional stabilizer bar structure, thus improving the lateral stability of the vehicle.

[0004] However, existing X-arms lack lightweight design and have significant limitations. They are all based on experience, resulting in excessive weight, large redundancy in structural performance, and a lack of reliable design methods.

[0005] Therefore, there is an urgent need for an X-arm for vehicle rear suspension systems and its design method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an X-arm for a vehicle rear suspension system and its design method, which has the advantages of modularity and lightweight, reducing the number and weight of parts in the automotive rear suspension system.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] An X-arm for a vehicle rear suspension system includes a body and a reinforcing rib. The upper part of the body is provided with a short connecting arm, and the lower part of the body is provided with a long connecting arm. The reinforcing rib is provided on the left and right sides of the body. The body has a symmetrical structure.

[0009] Preferably, the body is a hollow, uniform wall thickness structure, the end of the short connecting arm is provided with a first ball pin for connecting with the vehicle axle, and the end of the long connecting arm is provided with a second ball pin for connecting with the vehicle frame crossbeam.

[0010] Preferably, four reinforcing ribs are provided to increase the rigidity of the X-arm structure.

[0011] Preferably, the height of the reinforcing rib is negatively correlated with the size of the fillet radius of the body, and the fillet radius of the body is 100mm-500mm.

[0012] A design method for an X-arm for a vehicle rear suspension system, characterized by comprising the following steps:

[0013] S1: Use a similar vehicle model to replace the new vehicle for road testing and obtain road surface data;

[0014] S2: Establish a dynamic model based on the acquired road surface spectrum and decompose the load according to the model;

[0015] S3: Use the forces and moments at the ball pin of the X-arm obtained from load decomposition as boundary conditions and perform structural optimization to obtain the initial scheme;

[0016] S4: Based on the structural optimization and considering casting factors, complete the scheme optimization and perform strength verification on the optimized scheme;

[0017] S5: If the strength meets the requirements, the solution is complete; otherwise, repeat step S4 above.

[0018] Preferably, the road test and road surface spectrum acquisition in step S1 specifically involves: acquiring the required road surface spectrum through test track roads and virtual test track roads.

[0019] Preferably, the road surface spectrum in step S1 specifically includes: establishing the suspension, steering, engine, frame and cab subsystems of the whole vehicle using hard point layout.

[0020] Preferably, the data used to establish the dynamic model in step S2 includes: leaf spring stiffness, damper, stabilizer bar, and bushing data, which are obtained through road test.

[0021] Preferably, the step S2 of establishing the dynamic model further includes: after completing the construction of the dynamic model, calibrating the KC characteristics of the vehicle chassis, and optimizing the model based on the calibration results.

[0022] Preferably, the structural optimization in step S3 includes: topology optimization, shape optimization, size optimization, and morphology optimization.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This X-arm serves the dual purpose of a thrust rod and a lateral stabilizer bar, combining the advantages of modularity and lightweight design, thus reducing the number and weight of parts in the automotive rear suspension system.

[0025] 2. Based on the road surface load at the test site, and using a combination of testing and simulation, the load is decomposed through a multibody dynamics model to obtain the force and moment at the ball pin of the X-arm. The inertia release method is used as the boundary for structural optimization. Based on the optimization results, the structural design scheme is determined, and the design is strength-checked. The design method of this invention optimizes the material distribution of the X-arm structure, avoids the shortcomings of relying on experience design, and compared with existing designs, reduces the number of repeated modifications, improves the safety factor, and reduces the weight of the structure.

[0026] 3. Based on the stress results of the X-arm, the cross-section of the entire structure gradually decreases, so that the material of the X-arm satisfies the force flow distribution and is designed as an equal stress structure as much as possible.

[0027] 4. Since the body is a hollow structure and the two sides of the body are rounded, when the rounded corners are small, the weight of the structure can be effectively reduced. However, this can lead to excessive stress concentration in the structure. Therefore, four reinforcing ribs are added to reduce the stress in this area, which reduces the weight of the X-arm while ensuring its strength.

[0028] 5. The body is designed with a uniform wall thickness structure, which can be adjusted to meet the needs of different vehicle models with different loads, and it is also easy to cast, reducing design and manufacturing costs. Attached Figure Description

[0029] Figure 1 This is the front view of the present invention.

[0030] Figure 2 This is a side view of the present invention.

[0031] Figure 3 This is a structural perspective view of the present invention.

[0032] Figure 4 This is a flowchart of the method of the present invention.

[0033] Figure 5 This is a schematic diagram of the simulation results of the rear axle reverse 6° roll condition of the present invention;

[0034] Figure 6 This is a schematic diagram of the simulation results of the braking conditions of the present invention;

[0035] Figure 7 This is a schematic diagram of the simulation results of the clutch release misoperation condition of the present invention;

[0036] Figure 8 This is a schematic diagram of the simulation results of the serpentine working condition of the present invention;

[0037] Figure 9 This is a schematic diagram of the simulation results of the lateral working condition of the present invention.

[0038] The labels shown in the attached diagram:

[0039] 1. Main body; 2. Short connecting arm; 3. Long connecting arm; 4. Reinforcing rib. Detailed Implementation

[0040] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0041] In this invention, terms such as "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "side," and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only to facilitate the description of the structural relationships of the various components or elements of this invention and do not specifically refer to any component or element in this invention. They should not be construed as limiting the invention.

[0042] In this invention, terms such as "fixed connection," "connected," and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0043] Example: An X-arm for a vehicle rear suspension system and its design method

[0044] like Figure 1-3 As shown, this X-arm is symmetrical vertically and consists of a main body, a short connecting arm, a long connecting arm, and reinforcing ribs. The main body is a hollow, uniformly thick-walled structure for ease of design and casting. The short connecting arm is connected to the axle via ball joints, and the long connecting arm is connected to the frame crossbeam via ball joints. Four reinforcing ribs are designed on both sides to enhance the structural rigidity of the X-arm and reduce stress concentration on both sides of the structure under torsional conditions. The height of the reinforcing ribs is negatively correlated with the radius of the fillet, and it is recommended that the radius of the fillet be set between 100mm and 500mm.

[0045] The body is a hollow, uniform wall thickness structure, and the thickness can be adjusted. The X-arm can be designed by adjusting the wall thickness of the body to meet the needs of suspension systems with different loads. The short connecting arm is connected to the axle through the first ball pin, and its end mounting holes are coaxial. The long connecting arm is connected to the frame crossbeam through the second ball pin.

[0046] The optimal height of the ribs of this X-shaped arm should be determined through simulation analysis. The rounded corners on both sides should be arranged reasonably to ensure a smooth structural transition and eliminate stress concentration in this area.

[0047] The main body is a hollow, uniform wall structure. The wall thickness is determined by the load of the entire vehicle. The two sides of the main body are rounded. When the rounded corners are small, the structural weight can be effectively reduced, but it will cause excessive stress concentration in the structure. Therefore, four reinforcing ribs are added to reduce the stress in this area, which reduces the weight of the X-arm while ensuring strength. The radius of the rounded corners and the height of the ribs are determined by simulation analysis results.

[0048] like Figure 4 As shown, the design method of the X-arm includes the following steps:

[0049] S1: Use a similar vehicle model to replace the new vehicle for road testing and obtain road surface data;

[0050] S2: Establish a dynamic model based on the acquired road surface spectrum and decompose the load according to the model;

[0051] S3: Use the forces and moments at the ball pin of the X-arm obtained from load decomposition as boundary conditions and perform structural optimization to obtain the initial scheme;

[0052] S4: Based on the structural optimization and considering casting factors, complete the scheme optimization and perform strength verification on the optimized scheme;

[0053] S5: If the strength meets the requirements, the solution is complete; otherwise, repeat step S4 above.

[0054] The road surface spectrum required for load decomposition can be obtained through road tests at the test track, but it is not limited to this; the required road surface spectrum can also be obtained through a virtual test track.

[0055] Based on the hard point layout of the whole vehicle, subsystems such as suspension, steering, engine, frame, and cab are established. To ensure the accuracy of the model, the modeling input data such as leaf spring stiffness, shock absorber, stabilizer bar, and bushing in the dynamic model need to be obtained through experiments.

[0056] The frame should be replaced with a flexible body. If the test conditions are met, the modal frequencies of the flexible body should be calibrated to ensure that the error between the test and the simulation is within 15%.

[0057] After completing the dynamic model, in order to further improve the accuracy of the dynamic model, the KC characteristics of the whole vehicle chassis were calibrated. Based on the calibration results, the simulation model was optimized to ensure that the whole vehicle modeling requirements meet the accuracy requirements of load decomposition.

[0058] Structural optimization methods include topology optimization, shape optimization, size optimization, and morphology optimization. One or more of these methods can be used to obtain the initial design scheme of the X-arm in the initial design stage.

[0059] like Figure 5-9As shown, the diagram includes a 4.5° roll in the same direction as the rear axle, a 6° roll in the opposite direction, a braking condition, a clutch release misoperation condition, a serpentine condition, and a lateral condition. The maximum stress is 657 MPa. The main body material is QT1000-6 with a yield strength of 700 MPa and a safety factor of 1.15. The illustrated structure is the final optimized structure based on simulation results. Compared with existing designs on the market, it improves the safety factor and reduces the structural weight. If other materials are used, the existing structure needs to be redesigned according to the design method described in this invention.

Claims

1. An X-arm for a vehicle rear suspension system, characterized in that, The device includes a main body and reinforcing ribs. A short connecting arm is located at the upper part of the main body, and a long connecting arm is located at the lower part of the main body. The reinforcing ribs are located on the left and right sides of the main body, which has a symmetrical structure. The main body is a hollow, uniformly thick-walled structure. A first ball joint is located at the end of each short connecting arm for connection to the vehicle axle, and a second ball joint is located at the end of each long connecting arm for connection to the vehicle frame crossbeam. Four reinforcing ribs are provided to increase the rigidity of the X-arm structure. The height of the reinforcing ribs is negatively correlated with the radius of the main body's fillet, which ranges from 100mm to 500mm.

2. A design method for an X-arm used in the vehicle rear suspension system as described in claim 1, characterized in that, Includes the following steps: S1: Use a similar vehicle model to replace the new vehicle for road testing and obtain road surface data; S2: Establish a dynamic model based on the acquired road surface spectrum and decompose the load according to the model; S3: Use the forces and moments at the ball pin of the X-arm obtained from load decomposition as boundary conditions and perform structural optimization to obtain the initial scheme; S4: Based on the structural optimization results and considering casting factors, complete the scheme optimization and perform strength verification on the optimized scheme; S5: If the strength meets the requirements, the solution is complete; otherwise, repeat step S4 above. The specific steps for conducting road tests and obtaining road surface spectra in step S1 are as follows: obtaining the required road surface spectra through test track roads and virtual test track roads; The data used to establish the dynamic model in step S2 includes modeling data for leaf spring stiffness, damper, stabilizer bar, and bushing. This data is obtained through road test. The step S2 of establishing a dynamic model also includes: after completing the construction of the dynamic model, calibrating the KC characteristics of the vehicle chassis, and optimizing the model based on the calibration results; The structural optimization in step S3 includes: topology optimization, shape optimization, size optimization, and morphology optimization.

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