Optimization method for light truck rear suspension hard point matching

Abstract

This invention discloses a method for optimizing the hard point matching of the rear suspension of a light truck, comprising the following steps: Step 1: In CATIA software, the length of the main leaf spring, the length of the straight section of the leaf spring, and the estimated front and rear mounting points of the leaf spring are designed using parametric variables; Step 2: Using the sketching tool of CATIA software, the constraint relationship between the arc height and radius of the main leaf spring is established, and the outline of the main leaf spring is generated; Step 3: A suspension system skeleton model is built, and the center position of the axle tube and the wheel center point are derived based on the center of the main leaf spring and the total thickness of the leaf spring; Step 4: The wheel center point position, leaf spring mounting attitude angle, and leaf spring hanger attitude angle are measured to see if they meet the target requirements; if they do not meet the first design requirements, they are readjusted; Step 5: Based on the leaf spring arc of the design load, the leaf spring arc height is adjusted to the set value, and the corresponding wheel center point position is recorded after adjustment; the longitudinal runout gradient of the wheel center under the design load is calculated; Step 6: The rear suspension hard point data is output. This invention facilitates suspension engineers in quickly designing and optimizing rear suspension hardpoints, greatly saving design and development time and shortening the design and development cycle of light trucks.

Description

Technical Field

[0001] This invention belongs to the technical field of light truck suspension system design and development. Specifically, this invention relates to a method for optimizing the matching of hard points in the rear suspension of a light truck. Background Technology

[0002] Light truck suspension systems such as Figure 5 As shown, the leaf spring is mounted on the rear axle 5 via the front coil lug 1, the rear coil lug 4, and the rear hanger lug 3, with the rear axle assembly rigidly connected to the wheel assembly 6. The static radius of the wheel, the height of the rear axle tube relative to the leaf spring mounting base, and the thickness of the leaf spring determine the distance in the Z-direction between the center of the main leaf spring plate and the ground. The hardpoint positions of the front coil lug 1 and the rear hanger lug 3 in the vehicle coordinate system, the length of the main leaf spring plate, and the arc height, stiffness, and hanger length of the leaf spring under design load determine the movement trajectory of the leaf spring.

[0003] During its movement, the leaf spring is guided by its main leaf. The longitudinal center plane of the leaf spring is used as its projection plane (e.g., ...). Figure 6 As indicated, the leaf spring assembly can be simplified into three parts: the straight section 8 in the middle of the main leaf, the front arc section 7, and the rear arc section 10. The straight section 8 in the middle of the main leaf is tangentially connected to the front arc section 7 and the rear arc section 10, and the arc section is tangentially connected to the coil lug section. The leaf spring is rigidly connected to the rear axle mounting bracket via the center bolt 9 and the U-bolt. The rear coil lug of the leaf spring moves in an arc with the mounting point on the lug as the center and the length of the lug as the radius.

[0004] In the design and development of light trucks, determining the rear suspension hardpoint is one of the most crucial tasks in the early stages. During automotive design and development, the suspension hardpoint determines the trajectory of the vehicle's wheels, significantly impacting its straight-line stability and ride comfort. Currently, the process for determining the rear suspension hardpoint of light trucks is complex, involving numerous steps and resulting in significant time consumption.

[0005] This paper provides a method for optimizing the hard point matching of the rear suspension of light trucks, specifically focusing on how to quickly output the optimized hard points of the rear suspension to shorten the design and development cycle of light trucks. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a method for optimizing the hard point matching of the rear suspension of light-duty trucks, with the purpose of ensuring the rapid output of optimized hard points for the rear suspension and shortening the design and development cycle of light-duty trucks.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for optimizing the hard point matching of the rear suspension of a light truck, comprising the following steps:

[0008] Step 1: In CATIA software, design the main leaf length, straight section length, pre-prediction mounting point position, and post-prediction mounting point position of the leaf spring using parametric variables.

[0009] Step 2: Using the sketching tools in CATIA software, establish the constraint relationships between the arc height and radius of the main leaf spring, and generate the outline of the main leaf spring.

[0010] Step 3: Build a suspension system skeleton model. Using the center of the main leaf spring as a reference point and combining the total thickness of the leaf spring, derive the position of the axle tube center and the wheel center point.

[0011] Step 4: Measure whether the wheel center point position, leaf spring mounting posture angle, and leaf spring shackle posture angle meet the target requirements; if they do not meet the first design requirements, readjust the hard point position of the front coil lug of the leaf spring, the hard point position of the rear shackle, and the arc height, and perform iterative optimization according to the set process until the wheel center point position, leaf spring mounting posture angle, and leaf spring shackle posture angle meet the requirements.

[0012] Step 5: Using the leaf spring curvature under the design load as a reference, adjust the leaf spring curvature height to the set value and record the corresponding wheel center point position after adjustment; calculate the longitudinal runout gradient of the wheel center under the design load.

[0013] Step 6: Output the rear suspension hard point data.

[0014] In step 5, if the longitudinal runout gradient of the wheel center does not meet the second design requirements, the arc height of the leaf spring under the design load or the hard point position in step 4 is adjusted, and iterative optimization is performed according to the set process until the longitudinal runout gradient of the wheel center under the design load meets the second design requirements.

[0015] In step 5, the set value is ±20mm.

[0016] The formula for calculating the longitudinal runout gradient of the wheel center is:

[0017]

[0018] Step 2 includes:

[0019] 2.1 Set the front coiling point and the rear suspension point of the leaf spring to remain stationary;

[0020] 2.2 Set the lower end of the leaf spring rear shackle to move in an arc, with the radius being the length of the leaf spring rear shackle;

[0021] 2.3. Set the arc portion of the leaf spring to be tangent to the straight section;

[0022] 2.4. The main leaf spring is divided into a left arc section, a right arc section, and a straight middle section, while the total length of the leaf spring remains unchanged.

[0023] 2.5. Establish the formula for calculating the curvature of the leaf spring;

[0024] 2.6. Establish the formula for calculating the leaf spring radius;

[0025] 2.7 Based on the main leaf arc height constraint under the design load of the leaf spring, automatically generate the main leaf outline diagram under the corresponding load.

[0026] In constraint 2.5, the leaf spring radius = (length of the main leaf spring - length of the straight section in the middle of the leaf spring) / 2)*180*1deg) / (PI*radius of the leaf spring).

[0027] In constraint 2.6, the leaf spring radius = (length of the main leaf spring - length of the straight section in the middle of the leaf spring) / 2)*180*1deg) / (PI*leaf spring radian).

[0028] The first design requirement includes: the target range for the installation attitude angle of the leaf spring is 3.5°-5°.

[0029] The first design requirement includes: the target range for the attitude angle of the leaf spring lug is 10°-15°.

[0030] The first design requirement includes: the measured X and Z coordinate values ​​of the wheel center point are close to the load point position given by the overall arrangement, wherein the difference between the X and Z coordinate values ​​of the wheel center point and the design target value is <0.1mm.

[0031] The present invention provides a method for optimizing the hard point matching of the rear suspension of light trucks. During the design process, the hard point position and arc height position of the leaf spring are adaptively and quickly adjusted to meet the design requirements such as the mounting angle posture of the leaf spring, the swing angle of the leaf spring hanger, the wheel center position, and the longitudinal runout gradient of the wheel center. This method facilitates suspension engineers to quickly design and optimize the hard points of the rear suspension, greatly saves design and development time, and shortens the design and development cycle of light trucks. Attached Figure Description

[0032] This manual includes the following figures, which illustrate the following:

[0033] Figure 1 This is a flowchart of the method for optimizing the hard point matching of the rear suspension of a light truck according to the present invention;

[0034] Figure 2 It is a parametric design drawing;

[0035] Figure 3 It is a sketch of a leaf spring;

[0036] Figure 4 This is a diagram of the suspension frame;

[0037] Figure 5This is a simplified diagram of the rear suspension structure;

[0038] Figure 6 This is a simplified diagram of a leaf spring structure;

[0039] The markings in the diagram are as follows: 1. Center of the front leaf spring lug; 2. U-bolt; 3. Lug mounting point; 4. Center of the rear leaf spring lug; 5. Rear axle; 6. Wheel assembly; 7. Front arc section of the leaf spring; 8. Straight section of the leaf spring; 9. Leaf spring mounting screw; 10. Rear arc section of the leaf spring; 11. Radius constraint of the leaf spring lug bushing; 12. Length constraint of the lug; 13. Curvature constraint of the leaf spring; 14. Radius constraint of the leaf spring; 15. Curvature constraint of the leaf spring; 16. Straight section constraint of the leaf spring; 17. Leaf spring lug swing angle; 18. Leaf spring mounting angle; 19. Wheel center point. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0041] like Figure 1 As shown, this embodiment of the invention provides a method for optimizing the hard point matching of the rear suspension of a light truck. By building a parametric model, the tangential relationship between the arc portion of the leaf spring and the lug portion, and the tangential relationship between the leaf spring portion and the straight section are established, including the following steps:

[0042] Step 1: In CATIA software, design the main leaf length, straight section length, pre-prediction mounting point position, and post-prediction mounting point position of the leaf spring using parametric variables.

[0043] Step 2: Using the sketching tools in CATIA software, establish the constraint relationships between the arc height and radius of the main leaf spring, and generate the outline of the main leaf spring.

[0044] Step 3: Build a suspension system skeleton model. Using the center of the leaf spring main leaf as a reference point and combining the total thickness of the leaf spring, derive the center position of the axle tube and the wheel center point. The center position of the axle tube is the center point of the axle tube of the rear axle connected to the leaf spring, and the wheel center point is the center point of the wheel assembly connected to the leaf spring.

[0045] Step 4: Measure whether the wheel center point position, leaf spring mounting posture angle, and leaf spring shackle posture angle meet the target requirements; if they do not meet the first design requirements, readjust the hard point position of the front coil lug of the leaf spring, the hard point position of the rear shackle, and the arc height, and perform iterative optimization according to the set process until the wheel center point position, leaf spring mounting posture angle, and leaf spring shackle posture angle meet the requirements.

[0046] Step 5: Using the leaf spring curvature under the design load as a reference, adjust the leaf spring curvature height to the set value and record the corresponding wheel center point position after adjustment; calculate the longitudinal runout gradient of the wheel center under the design load.

[0047] Step 6: Output the rear suspension hard point data.

[0048] Specifically, during the vehicle design and matching development process, by presetting the total length of the main leaf spring and the length of the hanger, and combining the position of the wheel center under the design load input by the overall layout, the next key task is to determine the hard point position of the front coil lug and the hard point position of the rear hanger.

[0049] This invention belongs to the field of light truck suspension system design and development. In the embodiments of this invention, after confirming the selection of leaf springs, rear axles and tires, a rear suspension frame model is built, and the hard point position of the leaf springs is quickly adjusted to meet the design requirements such as wheel center position, leaf spring mounting angle, leaf spring hanger swing angle and wheel center longitudinal runout gradient.

[0050] In this embodiment of the invention, based on the theory of equal arc length during the deformation of the leaf spring, a parametric model using CATIA software is used to establish the relationship between the arc height and radius during the leaf spring's movement. This allows for rapid adjustment and iterative optimization by matching parameters such as the leaf spring lug swing angle, mounting posture angle, wheel center position, and wheel center longitudinal coordinate gradient, through adjusting the hardpoint positions of the front and rear leaf springs. The optimized hardpoints of the rear suspension can be quickly output.

[0051] The leaf spring main body consists of three parts, the three parts being the left arc section (i.e., Figure 6 The front arc portion and the right arc portion (i.e.) Figure 6 The back arc section and the middle straight section (i.e.) Figure 6 The front arc section (in the middle) is located between the left and right arc sections, and the straight middle section is tangentially connected to both the left and right arc sections. The rear lug of the leaf spring moves in an arc with the mounting point on the lug as the center and the length of the lug as the radius.

[0052] In step 1 above, in CATIA software, the length of the main leaf spring, the length of the straight section of the leaf spring (i.e., the length of the middle straight section), the estimated front mounting point position of the leaf spring (i.e., the front lug mounting point position of the leaf spring), and the estimated rear mounting point position of the leaf spring (i.e., the rear lug mounting point position of the leaf spring) are designed using parametric variables.

[0053] In step 1 above, a parametric relationship is established based on the length of the main leaf spring, the distance between the center of the main leaf spring and the center of the bridge tube, the arc of the design load of the leaf spring, and the position of the mounting hard point of the leaf spring.

[0054] like Figure 2As shown, in this embodiment of the invention, the length of the main leaf spring is 800mm, the distance between the center of the main leaf spring and the center of the bridge tube is 800mm, the length of the straight section in the middle of the main leaf spring is 110mm, and the arc height during the movement of the leaf spring is 55mm.

[0055] In step 2 above, a sketch of the main leaf spring is created in CATIA software, and the following constraints are established:

[0056] 2.1 Set the front coiling point and the rear suspension point of the leaf spring to remain stationary;

[0057] 2.2 Set the lower end of the leaf spring's rear sling to move in an arc. The radius of this arc is set to the length of the leaf spring's rear sling. (e.g., leaf spring grass...) Figure 3 As shown in constraint 12 (the length of the rear lug of the leaf spring is 80mm);

[0058] 2.3. Set the arc portion of the leaf spring to be tangent to the straight middle section;

[0059] 2.4. The main leaf spring is divided into a left arc section, a right arc section, and a straight middle section, while the total length of the leaf spring remains unchanged.

[0060] 2.5. Establish the formula for calculating the curvature of the leaf spring;

[0061] 2.6. Establish the formula for calculating the leaf spring radius;

[0062] 2.7 Based on the main leaf arc height constraint under the design load of the leaf spring, automatically generate the main leaf outline diagram under the corresponding load.

[0063] In constraint 2.5 above, the formula for calculating the leaf spring curvature is: Leaf spring curvature = (Length of the main leaf spring - Length of the straight section in the middle of the leaf spring) / 2) * 180 * 1 deg) / (PI * Leaf spring radius), as follows. Figure 3 As shown in constraint 13 (angle 19.344°).

[0064] In constraint 2.6 above, the formula for calculating the leaf spring radius is: Leaf spring radius = (Length of the main leaf spring - Length of the straight section in the middle of the leaf spring) / 2) * 180 * 1 deg) / (PI * Leaf spring radians), as follows. Figure 4 As shown in constraint 13 (angle 19.344°).

[0065] In the above constraint 2.7, based on the main leaf arc height constraint 15 under the leaf spring design load, the main leaf sketch of the corresponding load (arc height) can be automatically generated, as shown in 3.

[0066] In step 3 above, given the relatively small deformation of the front and rear axles and rims of the light truck, the center of the leaf spring main leaf and the leaf spring, along with the rear axle and wheel assembly, are set as rigid connections. Based on the generated leaf spring profile under the design load, a suspension system skeleton model is constructed, as follows: Figure 4 As shown.

[0067] In step 4 above, the installation angle, lug angle, and wheel center position of the leaf spring are measured to determine whether they meet the design target requirements. The first design requirements include: the design target range for the leaf spring installation attitude angle is 3.5°-5°; the design target range for the leaf spring lug attitude angle is 10°-15°; and the measured X and Z coordinates of the wheel center point of the wheel assembly are close to the load point position given by the overall layout, with the difference between the X and Z coordinates of the wheel center point and the design target values ​​being <0.1mm. The X / Z coordinates represent the horizontal (front-to-back) and vertical (up-down) positions of the wheel center in the vehicle coordinate system. If the wheel center position meets the requirements, it indicates that the leaf spring installation arc and free radius are consistent with the design values.

[0068] In step 4 above, after regenerating the suspension frame model by adjusting the hard point of the leaf spring front coil lug, the mounting point of the hanger lug, and the arc height of the leaf spring, the mounting angle of the leaf spring, the hanger lug angle, and the wheel center position are measured until the target value is reached.

[0069] In step 5 above, if the longitudinal runout gradient of the wheel center does not meet the second design requirements, the arc height of the leaf spring under the design load or the hard point position in step 4 shall be adjusted, and iterative optimization shall be carried out according to the set process until the longitudinal runout gradient of the wheel center under the design load meets the second design requirements.

[0070] In step 5 above, the setting value is ±20mm. Record the leaf spring arc height in step 4, adjust the arc height by ±20mm, record the wheel center position in the corresponding suspension frame model diagram, and calculate the longitudinal runout gradient of the wheel center under the design load using the wheel center longitudinal runout gradient calculation formula (unit mm / m, target value <100mm / m).

[0071] In step 5 above, the formula for calculating the longitudinal runout gradient of the wheel center is:

[0072]

[0073] In step 6 above, the hard point of the leaf spring front coil lug, the mounting point of the hanger, and the arc height of the leaf spring are adjusted until the mounting angle of the leaf spring, the hanger angle, the wheel center position, and the longitudinal runout gradient of the wheel center meet the design requirements, thereby outputting the rear suspension hard point position data, including the finally determined wheel center position, leaf spring mounting attitude angle, leaf spring hanger attitude angle, and wheel center longitudinal runout gradient.

[0074] The method for optimizing the hard point matching of the rear suspension of a light-duty truck according to embodiments of the present invention has the following advantages:

[0075] 1. A method for constructing a suspension frame model based on the theory of equal arc length of the main leaf spring;

[0076] 2. By using the suspension skeleton model, adjust the hard point of the leaf spring suspension and the arc height position under the design load to meet the design index requirements of leaf spring hanger swing angle, leaf spring installation attitude angle, wheel center position and wheel center longitudinal runout gradient, and finally output the position of the rear suspension hard point.

[0077] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for optimizing the hard point matching of the rear suspension of a light truck, characterized in that, Including the following steps: Step 1: In CATIA software, design the main leaf length, straight section length, pre-prediction mounting point position, and post-prediction mounting point position of the leaf spring using parametric variables. Step 2: Using the sketching tools in CATIA software, establish the constraint relationships between the arc height and radius of the main leaf spring, and generate the outline of the main leaf spring. Step 3: Build a suspension system skeleton model. Using the center of the main leaf spring as a reference point and combining the total thickness of the leaf spring, derive the position of the axle tube center and the wheel center point. Step 4: Measure whether the wheel center point position, leaf spring mounting posture angle, and leaf spring shackle posture angle meet the target requirements; if they do not meet the first design requirements, readjust the hard point position of the front coil lug of the leaf spring, the hard point position of the rear shackle, and the arc height, and perform iterative optimization according to the set process until the wheel center point position, leaf spring mounting posture angle, and leaf spring shackle posture angle meet the requirements. Step 5: Using the leaf spring curvature of the design load as a reference, adjust the leaf spring curvature height to the set value and record the corresponding wheel center point position after adjustment; Calculate the longitudinal runout gradient of the wheel center under the design load; Step 6: Output the rear suspension hard point data.

2. The method for optimizing the hard point matching of the rear suspension of a light truck according to claim 1, characterized in that, In step 5, if the longitudinal runout gradient of the wheel center does not meet the second design requirements, the arc height of the leaf spring under the design load or the hard point position in step 4 is adjusted, and iterative optimization is performed according to the set process until the longitudinal runout gradient of the wheel center under the design load meets the second design requirements.

3. The method for optimizing hard point matching of the rear suspension of a light truck according to claim 1, characterized in that, In step 5, the set value is ±20mm.

4. The method for optimizing the hard point matching of the rear suspension of a light truck according to claim 3, characterized in that, The formula for calculating the longitudinal runout gradient of the wheel center is:

5. The method for optimizing the hard point matching of the rear suspension of a light truck according to any one of claims 1 to 4, characterized in that, Step 2 includes: 2.1 Set the front coiling point and the rear suspension point of the leaf spring to remain stationary; 2.2 Set the lower end of the leaf spring rear shackle to move in an arc, with the radius being the length of the leaf spring rear shackle; 2.

3. Set the arc portion of the leaf spring to be tangent to the straight section; 2.

4. The main leaf spring is divided into a left arc section, a right arc section, and a straight middle section, while the total length of the leaf spring remains unchanged. 2.

5. Establish the formula for calculating the curvature of the leaf spring; 2.

6. Establish the formula for calculating the leaf spring radius; 2.7 Based on the main leaf arc height constraint under the design load of the leaf spring, automatically generate the main leaf outline diagram under the corresponding load.

6. The method for optimizing the hard point matching of the rear suspension of a light truck according to claim 5, characterized in that, In constraint 2.5, the leaf spring radius = (length of the main leaf spring - length of the straight section in the middle of the leaf spring) / 2)*180*1deg) / (PI*radius of the leaf spring).

7. The method for optimizing hard point matching of the rear suspension of a light truck according to claim 5, characterized in that, In constraint 2.6, the leaf spring radius = (length of the main leaf spring - length of the straight section in the middle of the leaf spring) / 2)*180*1deg) / (PI*leaf spring radian).

8. The method for optimizing the hard point matching of the rear suspension of a light truck according to any one of claims 1 to 4, characterized in that, The first design requirement includes: the target range for the installation attitude angle of the leaf spring is 3.5°-5°.

9. The method for optimizing hard point matching of the rear suspension of a light truck according to claim 8, characterized in that, The first design requirement includes: the target range for the attitude angle of the leaf spring lug is 10°-15°.

10. The method for optimizing hard point matching of the rear suspension of a light truck according to claim 8, characterized in that, The first design requirement includes: the measured X and Z coordinate values ​​of the wheel center point are close to the load point position given by the overall arrangement, wherein the difference between the X and Z coordinate values ​​of the wheel center point and the design target value is <0.1mm.

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